Relaxation Techniques

Relaxation Audio Sounds Lazy Summer Day

Relaxation Audio Sounds Lazy Summer Day

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Brain Evolution System

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Brain Evolution System Overview

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Couplings and from Cross Correlated Relaxation Application to Biomacromolecules 147

7.4 Cross-Correlated Relaxation for the Measurement of Projection Angles between Tensors 18 161 7.4.1 J-Resolved Constant Time Measurement of Cross-Correlated Relaxation Rates 165 7.4.2 Quantitative r Measurement of Cross-Correlated Relaxation Rates 168 7.4.4 Transferred Cross-Correlated Relaxation 173

Isovolumic relaxation period

During relaxation, ventricular pressure is determined by two overlapping processes the decay of the pressure actively developed during the preceding systole and the build up of the passive filling pressure. Together, these two components result in the effective pressure of the isovolumic relaxation period. The rapid fall in pressure can be approximated by a mono-exponential curve and described by its time constant t.88 Maximal negative dP dt and the duration of the isovolumic relaxation period have been also used for the evaluation of ventricular relaxation. The rate of relaxation is modulated by sympathetic tone and circulating catecholamines. It increases with positive inotropic stimulation and increasing heart rate. Interventions causing an increase in the rate and extent of relaxation are called positive lusitropic effects. A delay of ventricular relaxation can be caused by pressure or volume overload, which primarily prolongs the contraction. The delayed relaxation can affect the...

Relaxation of MT and MO Particles

As a rule, chromatin is reconstituted on a topoisomer of negative supercoiling sufficient to keep it out of the relaxation equilibrium (see Note 22, and Fig. 1). In practice, this implies to use topoisomers of ALk below -1.5 for MT and below -2.2 for MO (this criterion is met in Fig. 6). Moreover, reconstitution is made at a histone DNA ratio low enough for the amount of dimer particles to be negligible. tin relaxation buffer, add 2-3 U of DNA topoisomerase I, incubate for 30 min at 37 C, and put immediately on ice. 2. Dilute with 3-4 vol of ice-cold TE-BSA, load onto a chromatin gel (see Subheading 3.5.2.), and apply voltage as soon as possible after samples are loaded. Examples of relaxations are displayed in Fig. 6.

Teaching Relaxation Skills

The goal of teaching relaxation skills is to enable patients to relax as much as is possible and appropriate both throughout the day and at times of particular stress. This contrasts with procedures such as meditation, which provide a period of deep relaxation and time out as sufficient in themselves. Relaxation skills are best learned through three phases learning basic relaxation skills using relaxation at times of stress. The first stage involves practice under optimal conditions such as a quiet room in a comfortable chair - where there are no distractions and it is relatively easy to relax. Initially, a trained practitioner should lead the individual through the process of deep relaxation. This is augmented by continued practice at home, typically using taped instructions. The relaxation process most commonly taught involves alternately tensing and relaxing muscle groups throughout the body in an ordered sequence. As the individual becomes more skilled, the emphasis of practice...

Relaxation and Stress Management

Techniques that may be used include relaxation training, breathing re-training, biofeedback, yoga, meditation, rapid relaxation and the identification (using questionnaires) of our own behavior and attitudes that lead to anger and stress. Each week one of the patients is asked to recall a recent event that had stressed them or made them very angry and the group is shown stress management techniques to avoid this. Patients are taught a rapid relaxation and distraction technique that they can

Magnetic Relaxation In Ferrofluids

Neel Brownian Relaxation

Ferromagnetic particles suspended in a liquid carrier are generally referred to as ferroflu-ids 19 . The dynamic behavior of these ferrofluids is governed by two very different magnetization relaxation pathways. Either the magnetization can change within each magnetic particle (Neel relaxation) or the whole particle can rotate in the liquid (Brow-nian relaxation). We will first discuss each mechanism individually and then turn to systems with size dispersions, where both relaxation mechanisms can be present simultaneously. 4.3.1 Internal Magnetic Relaxation In the following we will neglect magnetic interactions between magnetic particles, which may arise from dipolar coupling. This assumption is nontrivial, but in the case of biologically functionalized magnetic nanoparticles, the ligand coating helps to separate the individual particles independent of their concentration. The important parameter for assessing the importance of interactions is the ratio of interaction to thermal...

Nuclear Magnetic Relaxation

Where (n - n e)t is the displacement from equilibrium, ne, at time t, (n - ne)0 is the displacement from equilibrium, ne, at time zero, and T is the relaxation time. Two types of relaxation processes are known with possibly different relaxation times. These are known as T1 and T2. Looking at Figure 3.17, one can imagine a 180 pulse that inverts the magnetization. Following the end of the pulse, relaxation processes begin to return magnetization to its initial state. This process is called T1 or longitudinal relaxation because it takes place in the direction of B0. If one uses a 90 B1 pulse, the magnetization is moved to the xy plane (Mxy) as in the rotating frame figure, Figure 3.17. This transverse magnetization rotates at the nuclear Larmor frequency and because some nuclear spins are faster and some are slower, the xy magnetization starts to fan out and lose coherence, eventually resulting in Mxy 0. The characteristic time for this process is called transverse relaxation or T2. The...

Determination of Protein Dynamics Using 15N Relaxation Measurements

Multidimensional NMR methods, combined with isotope labeling, can provide access to virtually every atom in a molecule, unique for protein structural studies. This not only allows characterization of the structure and interaction of proteins in their native milieu, but also provides unparalleled possibilities to obtain a complete atomic-level resolution picture of protein dynamics in a time range from picoseconds up to seconds, the range where most motions relevant to protein function take place. A significant number of 15N and 13C relaxation studies have been performed on a large number of proteins in the last decade, initiated by the pioneering work of Refs. 1 and 2 . In this chapter we review some experimental and analytical approaches to protein dynamics by 15N relaxation measurements and outline the current picture of protein dynamics revealed by NMR.

Stress Relaxation and Strain Hardening

Subsequent to these original formulations a number of refinements to these relationships have been proposed. Observations of persistent deformations after micropipette aspiration for extended periods of time formed the basis for the development of a model for long-term stress relaxation Markle et al., 1983 . The characteristic times for these relaxations were on the order of 1-2 h, and these times were thought to correlate with permanent rearrangements of the membrane elastic network. Another type of stress relaxation is thought to occur over very short times ( 0.1 s) after rapid deformation of the membrane either by micropipette Chien et al., 1978 or in cell extension experiments (Waugh and Bisgrove, unpublished observations). This phenomenon is thought to be due to transient entanglements within the deforming network. Whether the phenomenon actually occurs remains controversial. The stresses relax rapidly, and it is difficult to account for inertial effects of the measuring system...

Relaxation Editing

Vector away from the static field direction. Once perturbed, both a spinning gyroscope and a spinning nucleus tend to return to their original positions. The rate of return for a nucleus is on the order of seconds for small molecules in aqueous solution because nuclei are extremely weakly coupled to their environments. This return to equilibrium, or relaxation, of the polarized nuclear spin is often dominated by dipolar interactions with neighboring nuclei that have components of molecular motion at frequencies either near zero (transverse relaxation) or at the Larmor (NMR) frequency (longitudinal relaxation). The longitudinal relaxation time (rate) is termed T1 (R1 1 7 ), and the transverse relaxation time (rate) is T2 (R2 1 T2). For rotational motion of a nucleus characterized by a correlation time, t, in a fluid of low viscosity, such as water, the dipolar relaxation rates are given by

The movements of respiration

During inspiration the movements of the chest wall and diaphragm result in an increase in all diameters of the thorax. This, in turn, brings about an increase in the negative intrapleural pressure and an expansion of the lung tissue. Conversely, in expiration the relaxation of the respiratory muscles and the elastic recoil of the lung reduce the thoracic capacity and force air out of the lungs.

Ancient Greece And Rome

The narrative continues by explaining that the drug had been given to Helen by an Egyptian, For Egypt teems with drugs. There has been much speculation as to the identity of this substance some have suggested that it may have been cannabis (Singer and Underwood, 1962 Burton, 1894 edn a Walton, 1938). As the story continues the guests do not become sedated or start to hallucinate, and so presumably the nepenthe was given to promote relaxation and discourse rather than heavy intoxication, sedation or psychotomimetic effects. It has also been suggested that Greek warriors may have taken nepenthe as a courage-boosting intoxicant before charging into the violence of combat (Cooper, 1995). Others have speculated that the 'wine of the condemned' cited by the Greek writer Amos in about 700 BC as a method of reducing the pain of a slow death was also cannabis (Walker, 1954). In reality it is impossible to determine the identity of substances such as these from the vague descriptions given....

The Sarcoplasmic Endoplasmic Reticulum Ca2ATPase Pump

SERCA is one of the modes that controls the homeostasis of intracellular calcium. SERCA2 transports Ca2+ into the lumen of the reticulum by an ATP-dependent mechanism. By virtue of this ability, SERCA2 plays an important part in normal physiological function such as the contraction and relaxation cycle of cardiac muscle, as well as in the pathogenesis of certain diseases. In addition, the correct localisation of the SERCA protein in the ER is of the utmost importance. As stated above, the localisation signal occurs in a stretch of 28 amino acids at the N-terminus of the molecule (Guerini et al. 1998). Ankyrin, a cytoskeletal protein, also seems to be involved in the targeting of SERCA. This is indicated by its abnormal localisation in ankyrin - - mice. In these mutant mice, the absence of ankyrin also affects the localisation of ryanodine and inositol, 1, 4, 5-trisphophate (IP3) receptors (IP3R), both involved in calcium mobilisation (Tuvia et al. 1999). The ATP2A2 gene encodes the...

The structure of the book

This then leads to the study of other complementary or alternative approaches which can involve both physical and psycho-social measures. There are a variety of physical interventions, including electrical, heat and cold, massage and aromatics, and counter-irritation. However, there are also many interventions based on psychology that can help to prevent pain or to enable the sufferer to develop meanings for the pain that give him or her a greater sense of control over the situation. Other psychologically based approaches include relaxation and distraction.

Quantitative Estimation Of Regional Brain Iron With

Although ferritin in aqueous solution has a strong effect on transverse relaxation times, these changes are much less prominent in tissue. Estimation of transverse relaxation times in patients with PD, using a 1.5-T whole-body imaging system, showed reduced T2 values in substantia nigra, caudate, and putamen in PD patients as compared with healthy controls (40). The decrease was small, however, and because of substantial overlap between groups, the investigators were unable to differentiate individual patients from controls with T2 measurements. Vymazal et al. (41) reported nonsignificant T2 shortening in the substantia nigra in PD consistent with iron accumulation. A more complex relationship between brain iron changes and disease state in PD, however, was suggested by Ryvlin et al. (42). These authors reported decreased T2 in the pars compacta of PD patients, regardless of disease duration, but increased T2 values in the putamen and pallidum in those with duration of illness greater...

Nitric Oxide And Nitrogen Oxides

Nitric oxide is formed by the five-electron oxidation of one of the guanidino groups of l-arginine by nitric oxide synthases, and it is released in response to activation of endothelial cells by a variety of stimuli, such as shear stress, ATP, acetylcholine, bradykinin, and other vasodilators (1). As a small lipophilic molecule, nitric oxide can diffuse through membranes to reach its potential targets, such as soluble guanylate cyclase. In addition to its principal function in smooth-muscle relaxation, nitric oxide has been implicated in a number of important pathophysiological functions, such as the regulation of apoptosis, ion channel activity, and mitochondrial function (2-13). The selective reaction of nitric oxide with proteins, which regulates protein function in a reversible manner, provides a reasonable biochemical explanation for the ability of nitric oxide to regulate different aspects of cell biology. In addition, nitric oxide, via secondary reactions with oxygen and...

Adaptation of the Protein Overproducer to the Algal Medium

While expression in 13C- and or 15N-labeled media is usually straightforward, most organisms need to be adapted in 3 to 4 steps to growth in 2H2O (e.g. 50, 75, 90, 100 ). In addition, while formulating any deuterated medium, it is important to recall that the reading on pH meters equipped with normal glass electrodes is about 0.4 units lower in 2H2O than in H2O with the same hydrogen deuterium ion concentration 28 . Because of the different physical properties of 2H2O, growth may be slower than usual, and the timing for induction of protein expression may require adjustment. The extent of deuteration depends on the type of experiments that will be performed. For investigations of internal dynamics using 15N relaxation or for backbone assignment with triple-resonance

Suggested Readings And Resources

The helping interview (3rd ed.). Boston Houghton Mifflin Co. This classic text includes information in Chapter 1 on physical conditions such as the room, and in Chapter 4 on recording interviews. Davis, M., McKay, M., & Eshelman, E. R. (2000). The relaxation and stress reduction workbook. Oakland, CA New Harbinger. This practical and clearly written workbook is primarily for use with clients. However, because providing therapy is stressful, it makes sense for clinicians to apply the strategies outlined in this book to themselves. Diller, J. V., Murphy, E., & Martinez, J. (1998). Cultural diversity A primer for the human services. London International Thomson Publishing. This book offers both clinical and theoretical material designed to help professionals provide cross-cultural human services effectively. It includes interviews with professionals from four ethnic backgrounds Latino Latina, Native American, African American, and Asian American. Kabat-Zinn, J....

Summary and Future Trends

In b-carotene, the quantum yield of CTI via the T1 state has been determined to be in the order 15-cis (0.98) > 13-cis (0.87) > 9-cis (0.15) > 7-cis (0.12). The quantum yield of isomerization starting from the 15-cis isomer was extremely high so that 15-cis T1 could be detected by neither electronic absorption nor Raman spectrosco-py. The large difference in the quantum yield found between the central-cis and the peripheral-cis isomers supported the idea of the triplet-excited region that is localized in the central part of the conjugated chain. In spheroidene, on the other hand, the quantum yield of triplet-state isomerization was in the order, 15-cis (0.60) > 13-cis (0.52) > 9-cis (0.50) > 13'-cis (0.48). The lower quantum yields of CTI in spheroidene (in contrast to those in b-carotene) may be ascribable to the large peripheral groups hanging on both sides of the conjugated chain that give rise to a larger moment of inertia. The lower quantum yields facilitated the...

Parp Activation And Energy Substrate

FIGURE 3.2 Effect of the functional integrity of PARS on the changes in myocardial contractility in perfused hearts subjected to hypoxia-reoxygenation in vitro. (A) The maximal rates of pressure development (+dP dt, mmHg s, left panels) and the maximal rates of relaxation (-dP dt, mmHg s, right panels) in wild-type and PARS knockout hearts in control conditions (before hypoxia) and after 30 min of hypoxia and 30 min of reperfusion (after hypoxia). (B) The times to peak pressure (TPP, ms mmHg, left panels), and the 1 2 times to relaxation (RT1 2, ms mmHg, right panels) in wild-type and PARS knockout hearts in control conditions (before hypoxia) and after 30 min of hypoxia and 30 min of reperfusion (after hypoxia). Data represent mean SEM values for n 5 hearts in each group. *p < 0.05, **p < 0.01, and ***p < 0.001 represent significant differences between the respective wild-type and PARS deficient groups and p < 0.01 and p < 0.001 represent significant differences between the...

Selective Protonation of Methyl Groups in 2HLabeled Proteins

As described in the introduction, deuteration is routinely used to reduce the rapid transverse relaxation rates characteristic of larger proteins, leading to improvements in peak line widths and experimental sensitivity. Deuteration of all the carbon-bound protons maximizes the sensitivity gains that can be obtained from this labeling strategy, and has thus proven useful for in the assignment of backbone XH, 15N, 13C and side-chain 13C chemical shifts of large proteins. However, the elimination of all but the exchangeable protons significantly impedes structural studies that rely on conventional NOE approaches. Although in some cases it is possible to use only backbone 1HN-1HN NOEs to obtain a protein global fold, the accuracy of these structures is very low because of the small proportion of distance restraints between protons from nonsequential residues. These global folds tend to be less compact than high-resolution structures, with the backbone pairwise root-mean-squared deviation...

Annexins And Heart Disease

Annexin 6 has been shown in vitro to be a modulator of the sarcoplasmic reticulum Ca2+ -release channel, the cardiac L-type channel and the Na+ Ca2+ exchanger (Diaz-Munoz et al., 1990). Cardiomyocytes derived from an annexin 6 null mutant mouse show increased contraction and relaxation amplitudes and reduced 'time to peak relaxation', (Song et al., 2002). Heart-specific annexin 6 overexpression in a mouse resulted in dilation of the heart, acute diffusive myocarditis, moderate to severe fibrosis throughout the heart and frequency-dependent reduced shortening and rates of contraction of isolated cardiomyocytes (Gunteski-Hamblin et al., 1996) consistent with a role in negative inotopic calcium handling.

Linking Number Difference Associated with Particle Formation

Lko can be obtained upon relaxation with topoisomerase I, from the mean Lk value of the topoisomer equilibrium population (Fig. 1). Lko is usually fractional, and so is ALk. Alternatively, Lko is calculated from the equation (25) Fig. 1. The rule of thumb. DNA linking number change (ALk) associated with particle formation. The rule offers a convenient way to assess the supercoiling polarity of a crossing, i.e., DNA supercoiling polarity. Naked 350-360 bp mini-circles are relatively rigid, and relax into a single topoisomer when their size is close to exact multiples of the helical repeat, or two if their size is in between (see Subheadings 3.3.). It is interesting to compare this result with the 5-6 topoisomers obtained upon relaxation of a 4.3 kbp plasmid such as pBR322. When reconstituted with an octamer (MO), the same minicircles appear more flexible and relax into two topoisomers regardless of the exact size (see example in Fig. 7B). Flexibility still increases for tetramer...

Elaboration of Vasoactive Substances

One function of endothelium that may be important in vascular physiology is the ability to mediate relation of the underlying smooth muscle in response to appropriate stimuli. Endothelial-dependent relaxation is now recognized as resulting from release of nitric oxide, which is synthesized by endothelial cells in response to shear forces and various phar-macologic agents. Sjoberg and his co-investigators evaluated the ability of the transplanted aorta to mediate endothelial-dependent relaxation in the rat.22 This study used syngeneic donors and recipients, and the vascular grafts were transplanted with a mean ischemic time of 41 minutes. Thus, this study considered the best case situation of a graft transplanted with minimal possibility of immunologic response or adverse consequences of harvest, sterilization and storage. These grafts exhibited excellent preservation of endothelia-mediated relaxation at both three and 60 days after implant. Although this experimental protocol is...

Psychological Dependence

Psychological dependence can occur merely on a tablet or injection, regardless of its content, as well as to drug substances. Mild dependence does not require that a drug should have important psychic effects the subject's beliefs as to what it does are as important, e.g. purgative and diuretic dependence in people obsessed with dread of obesity. We are all physically dependent on food, and some develop a strong emotional dependence and eat too much (or the reverse) sexual activity, with its unique mix of arousal and relaxation, can for some become compulsive or addictive.

Viscoelastic Properties

Where Oj(t) and eH(x) are the time-dependent second rank stress and strain tensors, respectively, and Ciju(t - t) is the fourth-rank relaxation modulus tensor. This tensor has 36 independent elements for the lowest symmetry case and 12 nonzero independent elements for an orthotropic solid. Again, as for linear elasticity, a reduced notation is used, i.e., 11 1, 22 2, 33 3, 23 4, 31 5, and 12 6. If we apply Eq. (1.17) to the case of an orthotropic material, e.g., plexiform bone, in uniaxial tension (compression) in the 1 direction Lakes and Katz, 1974 , in this case using the reduced notation, we obtain Thus, for a more complete understanding of bone's response to applied loads, it is important to know its rheologic properties. There have been a number of early studies of the viscoelastic properties of various long bones Sedlin, 1965 Smith and Keiper, 1965 Laird and Kingsbury, 1973 Lugassy, 1968 Black and Korostoff, 1973 . However, none of these was performed over a wide enough range...

The Normal Adult Brain

Current animal studies using diffusion-weighted and T2-weighted MR imaging sequences investigated differences in brain diffusion and transverse relaxation time (T2) between young-adult (age 3 months) and adult (age 12 months) rats (Heiland et al 2002). The studies showed no differences in T2 relaxation time between both animal groups, either local or global. However, the mean ADC within the whole brain was lower in the adult animals than in the young-adult ones. ADC decrease was mainly found in rat cerebral cortex but not in other brain areas. These results can be attributed to an activity-related or CNS damage-related internal water shift from extracellular to intracellular space without a net increase of water content in brain tissue. These results disagree with the results of different studies in humans, where an age-related ADC increase was found. This ADC increase, however, was only significant for volunteers after their 6th decade of life (O'Sullivan et al 2001). There is no...

Photoactive Yellow Protein

By crossing of the transition state barrier, and relaxation from the excited state to the ground state by internal conversion 3 . This intermediate has a red-shifted absorption spectrum and still retains its hydrogen bonds with Tyr42 and Glu46. The C1-C7-C8-C9 dihedral angle (see Fig. 5.1 for numbering) of the Io intermediate has been calculated to be -80 3 , which corresponds with that observed in the crystal structure of a cryogenically trapped early intermediate of the photocycle 4 . It has been suggested that the light energy that drives the photocycle is stored in this highly strained cis conformation 3,5 . Within nanoseconds several relaxation processes of the strained chromophore and the hydrogen bonding network lead to the relaxed, pR, intermediate (also known as Ij or PYPL). Vibrational spectroscopy has been used to show that the hydrogen bond between Glu46 and the anionic chromophore is the same in the dark trans pG state as it is in the cis pR state 6 . Protonation of the...

Exercise Type Endurance Versus Resistance

To summarize, patients in risk groups B and C (compare Table 19-4) may benefit from a resistance training program with short stress phases (maximal capacity 10 repetitions) at < 60 MVC, interrupted by phases of muscle relaxation, without causing hemodynamic deterioration. As a supplementary training modality, resistance training can complement, but not replace, the well-established aerobic endurance training.

Diagnosis of Graves Disease

The diagnosis of Graves' disease, aside from a history of thyroid problems, uses measures of visual acuity, pupillary light responses, and ocular motility. The configuration and movement of the lid margins should be carefully studied. The slit-lamp examination should include the measure of intraocular pressure by applanation tonometry both in downgaze and in the primary position. Because of the foreshortened rectus muscle's traction on the globe, attempts to force the eye into the primary position often result in a marked, though transient, elevation of the intraocular pressure. Visual field testing and a sonographic determination of rectus muscle thickness by A-scan complete the workup. Echographic confirmation of rectus muscle thickening in the midportions of muscle belly, but with no thickening at the tendinous insertions, is characteristic of Graves' disease and differentiates it from orbital myositis, in which the inflammatory swelling extends all the way to the point of...

In Silico Dynamic Studies of Cis Trans Isomerization in Organic and Biological Systems

The reaction path of photochemical reactions is determined primarily by the topology of the excited singlet surfaces Sx (x 1, 2, ), along with the topology of the ground state S0 if no intersystem crossing to a triplet surface occurs. The most important characteristics of these potential energy surfaces (PESs) are the locations of minima, points of contact (e.g. conical intersections between S0 and S1), barriers and singlet-triplet intersection points. The shapes of the PESs are intimately tied to changes in the electronic wave function in relation to molecular geometry. Different approaches can help in the understanding of photoisomeriza-tion processes. Qualitative approaches are based on correlation diagrams expressed either in the valence bond (VB) or in the molecular orbital (MO) framework 1,2 . Although essential for the understanding of the nature and the symmetry of the electronic wave functions associated with the respective molecular geometries in the various electronic...

Isotope Labeling and NMR

Recent developments in technologies within structural biology should also play an important part for transmembrane proteins. The potential to incorporate stable isotopes would facilitate structure determination by NMR techniques. Although NMR technologies were long considered to be applicable only to smaller proteins, the development of transverse relaxation-optimized spectroscopy (TROSY) has made it possible to use NMR for larger proteins also 5 , even integral membrane proteins. For example, the OmpX and OmpA integral membrane proteins of E. coli were labeled with 13C 15N 2H isotopes and overex-pressed as inclusion bodies in bacterial cells. After solubilization in 6 M Gdn-HCl and reconstitution in detergent micelles, solution NMR techniques could be used to identify regular secondary structural elements 132 .

Myocardial Oxygen Consumption

Changes in stroke volume, whether caused by changes in preload, afterload, or inotropy, significantly alter the oxygen consumption of the heart. Changes in heart rate likewise affect myocardial oxygen consumption. The contracting heart consumes a considerable amount of oxygen because of its need to regenerate the large amount of ATP hydrolyzed during contraction and relaxation. Therefore, any change in myocardial function that affects either the generation of force by myocytes or

Prostate Cancer Stem Cells A Target for New Therapies

Deed, when AR mutations are observed, they frequently result in either enhanced androgen binding or a relaxation of the steroid specificity of the receptor, enabling it to activated gene expression after binding to other steroids, estrogens and even the commoner antagonists used for therapy (Culig et al. 1993 Linja and Visakorpi. 2004). Zero function mutations, such as those found in androgen insensitivity patients, are frequently toxic when re-expressed in prostate epithelial cells (Birnie and Maitland, unpublished data). However, the mechanism whereby the AR gene amplification arises remains unknown.

Neurohumoral control of coronary vascular tone

Substance P and CGRP immunoreactive nerve fibres are rare in the proximal region of epicardial coronary arteries and increase in number distally.83 Substance P and CGRP produce a marked relaxation of epicardial coronary arteries88 89 but exert only a weak vasodilatory effect on intramyocardial resistance vessels.89 90

Mitotic Versus Postmitotic Compartments

Paro and coworkers (65) constructed a Drosophila strain carrying a Pc-G response element-linked reporter gene. In temperature shift experiments, they reported loss of silencing over time during adulthood (i.e., an age-related loss) at this recombinant locus. How might relaxation or initiation of heritable silencing be established in the absence of DNA replication A speculative but potentially important possibility is that chromatin domains could be remodeled by repeated cycles of DNA damage and repair. Studies on budding yeast provide a precedent for this idea. In that organism (as in mammalian cells), double-stranded DNA breaks lead to activation of one or more nonhomologous end-joining (NHEJ) pathways. Ku proteins are thought to bind to, and facilitate, end joining, at least in part through mobilization from telomeric binding sites. Notably, SIR proteins are recruited to double-stranded DNA breaks in much the same manner (11,66). The product of the SIR3 gene, in particular, has been...

Sarcoplasmic Reticulum Proteins

Phospholamban, a small, 6-kDa pentameric protein, comprises polypeptide subunits 52 amino acids in length. The nonphoshorylated form of phospholamban is an inhibitor of sarcoendoplasmic reticulum calcium pump (SERCA) 2a, but inhibition is relieved upon phosphorylation of phospholamban by -adrenergic stimuli through cAMP-dependent protein kinase and Ca2+-dependent calmodulin kinase. The subsequent activation of SERCA leads to enhanced muscle relaxation rates and an increased cardiac contraction rate and force by releasing Ca2+ from SR through the ryanodine receptor.

Centriole Disorientation

Loss of orthogonal relationship between the centriole pair, observed during late Gj, is commonly said to be the leading event in centrosome reproduction (Figure 9.1b) 14-16 . Although this morphological change has been interpreted to mean a disjunction event, a proposition supported by the behavior of centrioles in Xenopus egg extracts 16 , it is not rigorously known if this represents the functional separation of the mother and daughter centrioles or rather a relaxation in their spatial association without loss of physical connection in somatic cells. Although the cen-trioles separate slightly at this time, the centrosome as a whole does not split until later in interphase.

Shear Stress And The Release Of Vasoactive Mediators

Furchgott and Zawadzki (1980) demonstrated that relaxation of vascular smooth muscle following acetylcholine administration was dependent on the integrity of the endothelium, which responded by upregulating the production of the free radical gas nitric oxide (NO), which was subsequently identified as the endothelium-derived smooth muscle relaxing factor. In the endothelium the isoform of nitric oxide synthase (eNOS) converts the amino acid L-arginine to L-citrulline and nitric oxide, shear stress being the most potent and direct regulatory factor of eNOS activity (Kuchan and Frangos, 1994) and gene expression (Noris et al., 1995), while low levels of shear stress and turbulent flow have the opposite effect. The sudden onset of flow induces a burst of nitric oxide production. This process is both calcium- and G protein-dependent. In contrast, steady shear stress induces a sustained release of nitric oxide that is calcium and G protein-independent (Kuchan and Frangos, 1994). Transient...

Oxygensensitive Mechanisms

Evidence that endothelial-derived adenosine is in part responsible for the dilation of rat femoral vessels during systemic hypoxia has been described above (Figure 9.4). Recently, evidence has been developed that the red cell itself may participate in the vascular response to lowered oxygen. It has been shown that hemoglobin deoxygenation in the passage of blood through the microcirculation causes release of ATP from the red blood cell (Sprague et al., 1996 Ellsworth, 2004), which may act on the arteriole. ATP could also act on the venular endothelium to cause release of prostaglandins, which could in turn diffuse to adjacent arterioles as reported by Hester and Hammer (2002), providing a feedback mechanism linked to HbO2 saturation in the microcirculation. The vascular network also possesses the capability of transmitting hyper- or depolarization, and it has been suggested that a vasodilator response is conducted upstream from the capillary network to the arterioles in contracting...

Morphine Onthe Central Nervous System

Morphine is the most generally useful high-efficacy opioid analgesic it eliminates pain and also allows subjects to tolerate pain, i.e. the sensation is felt but is no longer unpleasant. It both stimulates and depresses the central nervous system. It induces a state of relaxation, tranquillity, detachment and well-being (euphoria), or occasionally of unpleasantness (dysphoria), and causes sleepiness, inability to concentrate and lethargy, always supposing that this pleasant state is not destroyed by nausea and vomiting more common if the patient is ambulant. Excitement can occur but is unusual. Morphine excites cats and horses, though it is illegal to put this to practical use. Generally, morphine has useful hypnotic and tranquillising actions and there should be no hesitation in using it in full dose in appropriate circumstances, e.g. acute pain and fear, as in myocardial infarction or road traffic accidents.

Magnetic Resonance Imaging

In contrast to optical imaging, MRI has the advantages of a very high spatial resolution (25-100 im) and the ability to measure more than one physiological parameter at once using different radiofrequency pulse sequences (23). These features make MR very attractive for imaging reporter gene expression. The imaging signal is generated as a result of spin relaxation effects, which can be altered by atoms with high magnetic moments (e.g., gadolinium and iron). One particularly useful MR imaging signal amplification system is

Principles Of Analytical Pyrolysis

Analytical pyrolysis techniques, in which organic matter samples are thermally degraded in the absence of oxygen to form smaller more recognizable compounds, were developed during the 1960s and 1970s.20 During pyrolysis, the organic matter sample absorbs thermal energy and this energy becomes distributed throughout the molecular structure. This gives rise to the excitation of chemical bond vibrational modes. Relaxation of these same bond vibrational modes causes cleavage, both heterolytic and homolytic, of weaker bonds. In this way, bond scission leads to high yields of pyrolysis products. In most pyrolysis reactions the bonds of strongly electron-withdrawing

Localizing Nanoparticle Concentrations

Magnetic resonance imaging has been shown to be very well suited for diagnostic cancer imaging as a result of the exceptional anatomical resolution of this modality 29,30 . The basis of molecular MRI is generally based on the assumption that antibodies, peptides, or other targeting molecules, tagged with a magnetic contrast agent, binds to the target and produces a local magnetic field perturbation that results in an increased proton relaxation rate that is detectable by magnetic resonance techniques. Magnetic nanoparticles are a form of magnetic contrast agent in MRI. Para- and superparamagnetic agents such as Gd(III) and various forms of iron oxide in both molecular and nanoparticle form have been used in a broad range of MRI applications to enhance image contrast. This approach is only limited by the inherent sensitivity of MRI, and the specific pulse sequence chosen, to the presence and distribution of the magnetic contrast agent 25,26,31,32 .

Stages Of General Anaesthesia

Balanced surgical anaesthesia (hypnosis with analgesia and muscular relaxation) with a single drug requires high doses that will cause adverse effects such as slow and unpleasant recovery, and depression of cardiovascular and respiratory function. In modern practice, different drugs are used to attain each objective so that adverse effects are minimised.

Stress Management

Stress management training aims to change environmental triggers to the stress response and or change inappropriate behavioral, physiological, or cognitive responses that occur in response to this event. High levels of muscular tension can be reduced through relaxation techniques triggers can be identified and modified using problemsolving strategies cognitive distortions can be identified and changed through cognitive techniques such as cognitive restructuring and stressed behaviors can be changed through consideration and rehearsal of alternative behavioral responses. Many stress management programs teach simple relaxation techniques to minimize high levels of arousal. More complex interventions try to change cognitive (and therefore emotional) reactions to environmental triggers. A few address factors that initiate the stress response. Given the idiosyncratic nature of both the stressors that individuals experience and the complexity of changing their cognitive response, such...

Stabilizing Proteins by Intein Mediated Backbone Cyclization

Limited protein stability often hampers successful structure elucidation by X-ray crystallography and or NMR spectroscopy. Relaxation properties are usually improved at elevated temperatures, and multidimensional NMR experiments require sample lifetimes to extend over several days to weeks in order to acquire all the necessary data. In addition, the activity of contaminating proteases that are sometimes present in purified samples can be significant at the experimental temperatures. Therefore, the stability of a target protein can be a concern, in particular for expensive isotope-labeled proteins.

Achieving Better Sensitivity Less Noise and Fewer Artifacts in NMR Spectra

Artifactual peaks are even more dangerous than noise since they may not always be immediately recognized and may lead to erroneous assignments. An important source of artifacts is instability in the steady-state condition, e.g. if the relaxation delay is set too short. A commonly encountered example is presented by peaks which occur at the double quantum frequencies in DQF-COSY spectra. For detailed treatments of aspects of noise and artifacts see 4, 5 .

Amide Relevant Conformations in Proteins

Either cis to trans or trans to cis isomerization. However, in a proline-free variant of the a-amylase inhibitor tendamistat, for a small fraction of refolding molecules the relaxation time, which was 400 ms, could be assigned to CTIs of secondary amide peptide bonds 27 . Obviously, this type of isomerization during refolding must be universal in unfolded proteins. Many folding intermediates typically exist under strongly native refolding conditions with the native state containing cis prolyl bonds. For example, the refolding reaction of GdmCl-denatured RNase T1, which is a single domain protein of 104 amino acid residues encompassing two trans and two cis prolyl bonds, is properly described by a kinetic model containing four unfolded species (2n with n for the number of cis prolyl bonds) and three folding intermediates, all of which contain one non-native prolyl bond at least. For the three intermediates with non-native prolyl bonds relaxation rates of formation and decay ranging...

Neuromuscular Blocking Drugs

That voluntary muscle tone and reflex contraction be inhibited. This can be attained by deep general anaesthesia, regional nerve blockade, or by using neuromuscular blocking drugs. Deep general anaesthesia causes cardiovascular depression, respiratory complications, and slow recovery. Regional nerve blocks may be difficult to do or contraindicated, for example if there is a haemostatic defect. Selective relaxation of voluntary muscle with neuromuscular blocking drugs allows surgery under light general anaesthesia with analgesia it also facilitates tracheal intubation, quick induction and quick recovery. But it requires mechanical ventilation and technical skill. Neuromuscular blocking agents should be given only after induction of anaesthesia.

Other Muscle Relaxants

Drugs that provide muscle relaxation by an action on the central nervous system or on the muscle itself are not useful for this purpose in surgery they are insufficiently selective and full relaxation, even if achievable, is accompanied by general cerebral depression. But there is a place for drugs that reduce spasm of the voluntary muscles without impairing voluntary movement. Such drugs can be useful in spastic states, low back syndrome, and rheumatism with muscle spasm.

Human Cardiovascular Gene Therapy Current Status

Treatment of heart failure is another scenario for gene therapy, where it is close to entering clinical trials (10). Molecular targets for restitution of contractile function in the failing heart include interventions in calcium homeostasis e.g., overexpression of sarcoplasmic reticulum Ca-ATPase (SERCA) to increase contraction and relaxation velocity, or inhibition of phospholamban to increase SERCA levels (11,12) , in p-adrenergic signal transduction e.g., p-receptor overexpression to increase contractility, or inhibition of p-adrenoceptor kinases to reduce receptor desensitization (13) and in the cascade of apoptotic cell death e.g., overexpression of the anti-apoptotic factor Bcl-2 (14) .

Other factors affecting pulmonary vascular tone

Thromboxane, it became apparent that the endothelium played an important role in controlling the pulmonary circulation itself.32 In the 1980s it was shown that pulmonary and systemic vessels release a labile endothelium derived relaxing factor (EDRF) which modifies the vasopressor response to various pharmacological agents and to acute hypoxia. It is now clear that EDRF is nitric oxide (NO). The NO is synthesised from L-arginine by nitric oxide synthase. It then diffuses within the cell, or to another cell, where it stimulates soluble guanylyl cyclase or other haem containing proteins. This results in an increase in cyclic guanosine monophosphate (GMP) which produces the physiological effect. For example, in smooth muscle cells cyclic GMP decreases cell calcium which leads to relaxation of the muscle cell and vasodilation. As nitric oxide has a high affinity for haemoglobin with the formation of methaemoglobin, it has a half life measured in seconds. It is also rapidly oxidised to...

Valvular Heart Disease

Aortic stenosis is associated with LV hypertrophy and LV relaxation abnormalities and may, in some cases, eventually progress to LV systolic dysfunction. The progression of aortic stenosis is routinely monitored by serial Doppler echocardiographic examinations, permitting noninvasive estimates ofthe transvalvular gradient and aortic valve orifice area. The relation among natriuretic peptide plasma levels, disease severity, and symptoms has been examined in patients with aortic stenosis (182-184). BNP and NT-proBNP plasma levels were higher in symptomatic than in asymptomatic patients, even after adjustment for aortic valve area and ventricular function (184). NT-proBNP was found to be a sensitive marker of even mild LV hypertrophy (183) and to correlate significantly with the trans-valvular pressure gradient (182).

Events in the Cardiac Cycle

The heart serves as a muscular pump that generates varying pressures as its chambers contract and relax. Systole is the period of ventricular contraction. In the diagram shown below, pressure in the left ventricle rises from less than 5 mm Hg in its resting state to a normal peak of 120 mm Hg. After the ventricle ejects much of its blood into the aorta, the pressure levels off and starts to fall. Diastole is the period of ventricular relaxation. Ventricular pressure falls further to below 5 mm Hg, and blood flows from atrium to ventricle. Late in diastole, ventricular pressure rises slightly during inflow of blood from atrial contraction.

Marine Invertebrates of the Andaman and Nicobar Islands

Several steroidal, terpenoids, and acetylenic compounds isolated from nudibranchs were also found in sponges which they feed upon.204 The bioactive nucleoside characterised as 1-methyl-isoguanosine has been found in the sponge Tedania digitata205,206 as well as in the nudibranch Anisodoris nobilis.207-209 Isoguanosine isolated from marine nudibranch Diaulula sandiegensis210 produced hypotension and relaxation of smooth muscles in mammals. Hexadecylglycerol isolated from Archidoris montereyensis 211 showed high order of activity in vitro against Staphylococcus aureus and Bacillus subtilis. Sea-hares accumulate large quantities of metabolites in their digestive gland and skin. These compounds are believed to originate from the algae which they take as food. Aplysiatoxin, a toxic metabolite has been isolated both from the Hawaiian sea-hare Stylocheilus longicauda and also from blue-green alga Lynbrya majusticula212 on which it feeds. Aplysistatin is a well known antileukemic metabolite...

Hypotheses About Cellulose Microfibril Ordering Mechanisms

In our view, however, liquid crystalline self-organization is a highly unlikely mechanism for cell wall texture formation. In order to obtain a thermodynami-cally self-organized state, of which a liquid crystal is just one example, a number of requirements need to be met. First of all, a sufficient number of molecules must simultaneously interact. Secondly, the thermodynamical equilibrium state must be reached, requiring the molecules to exhibit both sufficient mobility and changes of conformation to equilibrate all pertinent degrees of freedom. It is not clear that any of these conditions hold at any given stage of cell wall deposition. The CMFs are deposited sequentially from membrane-bound cellulose synthases. They are co-deposited with matrix material into the limited space between the plasma membrane and the already extant cell wall. Under these circumstances their mobility is extremely reduced, if not nonexistent. The same holds a fortiori for the conformational changes. A CMF...

Stress Development Models

The viscoelastic stress model accounts for the time required for deformation and stress relaxation to occur. Several researchers have modeled heat and mass transfer with Luikov's model and viscoelastic stresses in foods. Cummings (57) and Litchfield (61) modeled pasta drying. Itaya et al. (62) modeled three-dimensional heat and mass transfer and stress development in starch sucrose bars, and Aki-yama et al. (63) studied crack formation and propagation in viscoelastic foods. Kim (60) modeled checking in crackers during cooling.

Dynamic Properties of iLBPs

NMR relaxation and exchange data have provided important insights into the backbone dynamics of various iLBP molecules. Using 15N-, 13C- and 2H-NMR techniques, the relative mobilities of the protein (backbone as well as side-chains) and the ligand have been investigated 75-77, 86, 101-105 . The backbone dynamics are influenced by the presence of the ligand, which stabilizes the overall protein structure. In fact, multiple stable conformational states in the portal region have been observed for H-FABP in the presence of a mixture of endogenous fatty acid ligands 88 . Moreover, the backbone relaxation and hydrogen deuterium exchange data strongly suggest that ligand binding properties such as affinity and specificity are related to the protein dynamics 78, 86 . Hence, the differences in the binding properties of certain iLBP types correlate with variations in their conformational stabilities, as indicated also by biochemical fluorescence-based denaturation studies 72, 106, 107 ....

The Impact of Stress Management

Unfortunately, from a scientific perspective, many stress management interventions are combined with other interventions such as exercise programs, making it difficult to isolate a specific therapeutic effect of the stress management. Nevertheless, the relatively small number of studies that have used stress management in isolation suggest a beneficial impact on these other goals. For instance, a meta-analysis of 27 trials of relaxation therapy in the rehabilitation of cardiac patients found that intensive supervised relaxation practice contributed to many secondary prevention outcomes - psychological, vocational, physiological, and clinical.4

Modulation of Pain by the Autonomic Nervous System

Perception of intestinal stimulation (61). Using brief distending stimuli in the intestine, the effect of sympathetic activation by LBNP on sympathetically mediated intestinal relaxation and on vagally mediated gastric relaxation was measured by corresponding barostats. The effect of LBNP on perception of duodenal distension was also compared to the perception of somatic stimulation. It was found that sympathetic activation significantly heightened perception of intestinal distension without modifying perception of somatic stimuli (perception scores increased by 41 and 2 , respectively). Also, the reflex responses to duodenal distension significantly increased during sympathetic activation both in the stomach and in the intestine (relaxation increased by 91 and 69 , respectively, with p < 0.05 for both).

Fluorescent probes in proteins and membranes

Membranes are more complex than the unrestricted rotational diffusion discussed above. To begin with, the fluorescent probe is no longer 'free' but is confined to some restricted geometry due to the local environment. The steady-state local orientational distribution of the fluorophore is no longer isotropic however the global orientational distribution of the larger host molecule is wholly random and the fluorescence anisotropy will tend towards zero. The two orientation relaxation processes can be separated by several orders of magnitude for tryptophan 214 in human serum albumin (HSA) the local tryptophan motion has a rotational lifetime on the order of 200 ps whilst HSA shows a rotational diffusion time of 20-30 ns depending on the biological molecules it transports. If the two orientational relaxation processes are independent, the fluorescence anisotropy is described by Two photon fluorescence anisotropy measurements yield anisotropy decays of a wholly equivalent form to Equation...

Regulation of Appetite in the Elderly

Adaptive Relaxation Stomach

During a meal, the fundus distends to accommodate food, a process termed adaptive relaxation. Food is then passed to the antrum after mixing with stomach secretions. Antral distension is the major signal for termination of a meal 1 . With aging, there appears to be impaired gastric fundal accommodation 6 due to impaired adaptive relaxation, which is caused by a decline in the local release of nitric oxide. Older mice have decreased nitric oxide synthase activity in their fundus 7 . The decline in adaptive relaxation that occurs with aging leads to more rapid antral filling. In addition, some studies suggested that large- Nitric Oxide, Adaptive Relaxation, and Appetite

Magnetic Resonance Imaging MRI and spectroscopy

Body Fat Distribution Mri

Of this macroscopic magnetisation, in a process called excitation. After switching off the RF waves, magnetisation returns to the thermal equilibrium in a time and direction dependent manner. This process is called relaxation and the changing macroscopic magnetisation induces an electrical signal in the receiver coil. Signal intensity in MRI is dependent not only on the proton density in the volume of interest, but also on the interaction between tissue protons and externally applied RF waves during the excitation, and on the interaction between nuclei within the tissue during the relaxation. The different physical properties of protons within water and fatty acid molecules result in strong differences in the time and phase dependent behaviours of these nuclei during the relaxation, producing a relaxation and phase dependent contrast for magnetic resonance imaging. T -relaxation based contrast can be used for volumetric measurements of subcutaneous and intra-abdominal fat...

Calcium Channel Blockers

Activation of calcium channels by an action potential allows calcium to enter the cells. There follows a sequence of events which results in activation of the contractile proteins, myosin and actin, with shortening of the myofibril and contraction of smooth muscle. During relaxation calcium is released from the myofibril and, as it cannot be stored in the cell, it passes out again through the channel. Calcium channel (also called calcium entry) blockers inhibit the passage of calcium through the voltage-dependent L- (for 'long-opening') class membrane channels in cardiac muscle and conducting tissue, and vascular smooth muscle, reduce available intracellular calcium and cause the muscle to relax.5

Endothelium derived nitric oxide

Nitric oxide is synthesised by at least two major NO synthase (NOS) isoforms. One is expressed constitutively in neurons and vasculature, and requires calcium and calmodulin binding for activation. This constitutive enzyme is involved in cell communication and is activated by an increase in intracellular calcium. The enzyme is in a soluble form in neural tissue, but it is membrane-bound in vascular endothelium. The other isoenzyme is expressed after induction by cytokines or endotoxin and participates in host defence. This inducible isoform has calmodulin bound as a subunit and produces NO continuously without requiring calcium. This isoenzyme may contribute to the pathophysiology associated with syndromes characterised by an overproduction of cytokines such as septic shock. It is present in macrophages, but is not normally found in endothelial cells or vascular smooth muscle unless induced by cytokines. The NOSs are mixed function mono-oxygenases which use NADPH. L-Arginine is...

Modulation of Brain Responses by Pharmacological Treatments

Associated with significant activation of the pACC, right insula, and right PFC. Amitriptyline treatment was not associated with either a significant subjective symptom improvement or changes in brain activation during the relaxing music condition. However, decreased activation in the pACC and the left posterior parietal cortex was observed during distension when associated with the auditory stressor. Even though adequately powered, this study had several shortcomings that may have affected the outcome. Patients had significant psychological comorbidities, making it difficult to determine if the effect of the drug was on IBS symptoms or anxiety. Given the well-known side effects of amitriptyline, it would seem that the study was inadequately blinded, and that exposure to drug during the initial session significantly affected the placebo response during the second session. Finally, the finding of pACC during the relaxation condition is different from generally observed activation of...

Fluorescence Spectroscopy

Fluorescence is the emission of radiation that occurs when an excited molecule returns to the ground state (Lakowicz, 1999). The relaxation of the excited molecules back to the ground state may occur by the radiationless process. Its presence results in a quenching of the fluorescence intensity. Fluorescence involves two processes absorption and subsequent emission. The shape of the emission band is approximately a mirror image of the absorption band if the vibronic structures of the two states are similar. Each process occurs in the time scale given by the inverse of the transition frequency ( 10-15s), but there is a time lag of about 10-9 s when the molecule exists in the excited state. Fluorescence occurs at a lower frequency than that of the exciting light. Because the detection frequency is different from the incident frequency, the sensitivity in fluorescence spectroscopy is high (sample concentration in the 10-8M range). Therefore fluorescence spectroscopy is widely used in the...

Matching of flow and metabolism

Concomitant accumulation of byproducts of metabolism. For example, as more ATP is consumed during periods of increased metabolic activity, adenosine is released into the interstitium. The accumulation of this and other vasodilator substances leads to smooth muscle relaxation in arterioles with increases in tissue perfusion. This represents a powerful regulator of flow in which perfusion is closely coupled with metabolic demands. Investigations have demonstrated that, during intense exercise, active hyperaemia can increase skeletal muscle blood flow as much as 20-fold.

Cardiac Cell Structure And Function

Troponin Tropomyosin

This results in a movement (ratcheting) between the myosin heads and the actin. The actin and myosin filaments slide past each other, thereby shortening the sarcomere length (this is referred to as the sliding filament theory of muscle contraction) (Fig. 3-4). Ratcheting cycles will occur as long as the cytosolic calcium remains elevated. Toward the end of the myocyte action potential, calcium entry into the cell diminishes and the sarcoplasmic reticulum sequesters calcium by an ATP-dependent calcium pump, sarco-endoplasmic reticulum calcium ATPase (SERCA see Fig. 3-3). As in-tracellular calcium concentration declines, calcium dissociates from TN-C, which causes a conformational change in the troponin-tropomyosin complex this again leads to tro-ponin-tropomyosin inhibition of the actin-binding site. At the end of the cycle, a new ATP binds to the myosin head, displacing the adenosine diphosphate (ADP), and the initial sarcomere length is restored. Thus, ATP is...

Coronary flow reserve

Tachycardia And Increased Contractility

Many studies have estimated CFR from the reactive myocardial hyperaemia that follows transient total coronary occlusion. If there is no hyperaemia, coronary vascular reserve is deemed to have been exhausted by having to compensate for a stenosis in the supply vessel, and the supply vessel is deemed to be critically constricted.164 Reactive hyperaemia is, however, the result of complex interactions between vasodilator metabolites, myogenic relaxation, and coronary capacitance.165 It is difficult to standardise because it varies with the duration of occlusion, basal coronaiy perfusion pressure, sympathetic tone, and

Practical description

Acetylcholine is the most commonly used vasodilator for assessing endothelium-dependent vasodilation. It is believed that the vasodilatory effect of acetylcholine is to bind to the muscarine receptor and activate endothelial NO-synthase, resulting in vascular relaxation. Although acetylcholine-induced vasodilation is mainly caused by endothelial cell NO release, potassium-ATP channels also play a role in acetylcholine induced vasodilation (Higashi & Yoshizumi 2003).

Role Of Histone Phosphorylation In Chromatin Dynamics And Its Implications In Diseases

Abstract In eukaryotic cells, relaxed interphase chromatin undergoes pronounced changes resulting in formation of highly condensed mitotic chromosomes. Moreover, chromatin condensation is particularly evident during mitosis and apoptotic cell death, whereas chromatin relaxation is necessary for replication, repair, recombination and transcription. The post-translational modifications of histone tails such as reversible acetylation, phosphorylation and methylation play a critical role in dynamic condensation relaxation that occurs during the cell cycle. Histone phosphorylation is believed to play a direct role in mitosis, cell death, repair, replication and recombination. However, definitive roles for this modification in these processes have not yet been elucidated. In this review, we discuss recent progress in studies of histone phosphorylation

Docking and Homology Modeling In

Clearly, flexible-receptor docking could help to alleviate the problem. A frequently followed alternative is to refine the initial complex between the protein model and the ligand, most commonly by relaxation with MD simulations (249-251).This may also be combined with free energy calculations to determine the binding mode most consistent with experimental affinity data (252). However, refinement does not overcome the problem that the initial conformation of the model may preclude the binding of certain ligands. This has, for example, been demonstrated by Schapira et al. in a virtual screening for retinoic acid receptor (RAR) antagonists based on an RAR homology model (201). The automatic selection procedure based on flexible ligand docking was followed by optimization of the selected candidates with flexible protein side chains using the ICM program (82,116,117). Nevertheless, some known ligands were r -peatedly missed by the screening algorithm because of incompatible binding site...

Pressure autoregulation

Autoregulation Coronary Hypertensive

A schematic diagram of the changes in blood flow to an organ over a wide range of perfusion pressures in the presence or absence of autoregulation is shown in Fig. 6.5. In the absence of autoregulation, pressure-flow relationships are linear, and increases in driving pressure lead to direct increases in perfusion. An autoregulatory curve is characterised by a large range of pressures during which flow remains relatively constant. vasodilation is achieved at lower perfusion pressures by relaxation of smooth muscle, and vascular smooth muscle constriction occurs at higher perfusion pressures to maintain constant flow. The ability to autoregulate assumes that a set point of basal vasomotor tone allows for this dilatation or constriction to occur. Flow varies directly with pressure when the limits of autoregulation are exceeded. In regional beds that are maximally vasodilated, for example by a drug such as dipyridamole, the process of autoregulation is eliminated and flow is directly...

Centriole Duplication

Shown as shaded barrels the appendages on the older centrioles represent sub-distal and distal appendages. The pericentriolar material is not shown in some cell types it surrounds both centrioles and in other types it is associated primarily with the older centriole. a. At the end of mitosis each daughter cell receives a single centrosome containing a pair of centrioles in close proximity. The centrioles are shown to be connected by a fibrous link. b. Centriole disorientation is seen as a relaxation of the tight orthogonal relationship between the older and younger centrioles in late G1. Although this is said to be the leading event of centrosome duplication, it is not known if this represents a disjunction event or the relaxation of a persistent connection. c. The start of centriole duplication is seen by the assembly of short pro-centrioles at right angles to the proximal ends of the two parental centrioles. The pro-centrioles elongate throughout the rest of interphase, reaching...

Structures Of The Cardiac Cytoskeleton Cell Adhesion And The Sarcomere

The major function of cardiomyocytes is in the cardiac contraction-relaxation cycle. The contractile proteins in cardiomyocytes constitute about 75 of the total volume of the myocardium, although only about one-third of the number of all the cells in the myocardium are cardiomyocytes. About half of each ventricular cell is occupied by myofibers, and about one-fourth to one-third by mitochondria. The major proteins involved in contraction and relaxation are the thin filament (composed of actin, tropomyosin, and C-, I-, and T-troponin) and the thick myosin filament. During contraction, the filaments slide over each other (A band) without the individual molecules of actin or myosin actually shortening, leading to a pulling together of the two ends of the fundamental contractile unit called the sarcomere (Fig. 1A,B). The sarcomere is limited on either side by the Z-disc (Z is an abbreviation for the German Zuckung, meaning contrac

Control of vascular tone

Resting tone reflects basal properties intrinsic to the smooth muscle cells and the modulating influence of several well defined extrinsic factors 231 . These include the metabolic demand of the organ, neural and humoral factors, paracrine modulators and physical forces like stretch and shear. The myogenic response which increases smooth muscle tone in response to stretch is largely mediated by specialized, distinct stretch operated calcium channels 232 . The transduc-tion of flow-related stimuli also intrinsically regulates blood vessels in the in vivo circulation. Flow produces shear that is readily detected by endothelial cells. Vasomotor responses to flow are predominantly dilator 233 . Nitric oxide (NO) derived from endothelial nitric oxide synthase (eNOS) 234 as well as endothelial cyclooxygenase products 235 have been implicated in the conversion of the endothelial shear response into smooth muscle relaxation. The role of NO in the resting circulation is indicated by the...

Clinical features

Ischial Spine

Wall and guided by a finger to the ischial spine, which can be palpated per vaginam. Alternatively, the needle can be introduced just medial to the ischial tuberosity to a depth of 1 in (2.5 cm). When the procedure is carried out bilaterally there is loss of the anal reflex (which is a useful test that a successful block has been achieved), relaxation of the pelvic floor muscles and loss of sensation to the vulva and lower one third of the vagina (see Fig. 99b).

Lay Led Self Care Management Programs

One model of a lay-led generic chronic-disease self-management program that has been adopted worldwide is known in the UK as the Expert Patient Programme, developed at Stanford University by Kate Lorig.10 In this program, two specially trained lay-people who have a chronic illness, using a manual and a preordained script, lead a group of other patients with chronic illnesses through a 2 hours a week, 6-week program. It involves problem solving, decision making, and confidence building to increase self-efficacy goal setting relaxation techniques and educational sessions on managing pain increasing activity levels and dealing with medical personnel. Evaluations have shown that it reduced hospital admissions and use of healthcare resources, increased feelings of self-efficacy, knowledge about the

Distension of Hollow Viscera

Using fixed-pressure distensions, the result is quite different if the gut contracts, both intraluminal volume and perception decrease (12). Hence, using these methods, perception of gut distension depends on the muscular activity of the gut, and varies upon contraction and relaxation. To overcome these problems, a new methodological approach, the tensostat, has been developed (13). The tensostat is a computerized air pump that applies fixed tension levels on the gut wall. Based on intraluminal pressure and intraluminal volume, the system calculates wall tension, by applying Laplace's law (either for the sphere or for the cylinder) and drives in the pump to maintain the desired tension level on the gut wall. Applying fixed-tension distensions, if the gut contracts, intraluminal volume decreases and intraluminal pressure increases, but perception remains unaffected. These data indicate that perception of gut distension in healthy subjects depends on stimulation of...

Arterial Spasm from Subarachnoid Hemorrhage

It is not surprising that the exact biochemical mechanism underlying the prolonged vasoconstriction of vasospasm is unknown since the nature of normal vascular constriction-relaxation is so incompletely understood. Most current concepts of smooth muscle contraction were initially gained by physiologists working with other forms of muscle. More than 100 years ago, while studying ventricular cardiac muscle contraction Ringer found that Ca2+ was a requirement. Within a decade Fletcher and Hopkins showed that lactic acid was produced during Calcium ions (Ca2+) were shown to be the activator of the contractile system by Weber and Wincur (58). The concentration of Ca2+ controls contraction and relaxation by an allosteric mechanism in which the flow of information is from Ca2+ to troponin to actin to myosin. The rise and fall of sarcoplasmic free Ca2+ is the fundamental means of controlling smooth muscle contraction and relaxation (59). increased by phosphorylation of the regulatory light...

Histone Deacetylase Inhibitors

Histone deacetylases (HDAC) catalyse the deacetylation of lysine residues at the amino termini of core nucleosomal histones (42). This process is associated with chromatin relaxation and uncoiling, which permits the transcription of various genes including the key cyclin-dependent kinase inhibitor, p21 (42). By inhibiting HDAC, histone deacetylase inhibitors (HDI) cause hyperacetylation of histones. Hyperacetylation of histone H3 leads to transcriptional up regulation of p21, cell cycle arrest and apoptosis in tumor cells (42,43). The HDI acid SAHA induced p21 expression in one of the two CML cell lines and induced expression of p27, a key cell cycle regulator, in both of them (42). SAHA treatment was also associated with down regulation of p210Bcr-Abl protein. Combination treatment of CML cell lines with SAHA and imatinib resulted in a greater level of apoptosis than was achieved with either agent alone (42,44). This combination also produced synergis-tic induction of apoptosis in...

Interaction of Sensory and Reflex Dysfunctions

Normally, ingestion of a meal induces a relaxation of the proximal stomach to accommodate the meal volume, and the magnitude of the relaxation is regulated by a complex net of reflexes (61,62). Hence, this partial relaxation prevents wall tension increments and symptoms, but still the residual contraction of the proximal stomach gently forces gastric content distally into the antrum and initiates gastric emptying. As the relaxatory input decreases, the proximal stomach regains tone and emptying progresses. A gastric hyporeactivity to relaxatory reflexes would predictably result in a defective volume accommodation of the proximal stomach and antral overload. In patients with functional dyspepsia, gastric tone and compliance are normal during fasting (47,48,63,64). However, the reactivity of the stomach to regulatory reflexes is abnormal, and the proximal stomach does not relax properly in response to reflexes arising from the antrum and the small intestine (14,48,65). Consequently,...

Structure in an Aqueous Solution

Nuclear magnetic resonance (NMR) spectroscopy has been used to study the structure of inulin in aqueous solutions. In addition, the use of low-angle laser light scattering, dynamic light scattering, and small-angle x-ray scattering following size exclusion chromatography has yielded information on the molecular weight distribution, hydrodynamic radii, and geometry of Jerusalem artichoke inulin (Eigner et al., 1988). Inulin was found to have a rod-like shape with maximum dimensions of 5.1 x 1.6 nm (length x mean diameter). 13C relaxation rate measurements indicate that the fructofuranoside units are not part of the polysaccharide backbone therefore, the structure is like a polyethylene glycol polymer with furanosides attached (Figure 5.1). This greatly increases the flexibility of the chains, which is reflected by a segmental motion that is two to three times faster than amylose (Tylianakis et al., 1995).

Preventing Reinfarction

Other studies have shown positive gains following shorter and more general stress management interventions. Blumenthal and colleagues,8 for example, assigned patients to a 4-month program of exercise or stress management training or usual treatment control. Participants in the stress management group were significantly less likely to have a cardiac event over the follow-up period than participants in either other condition. Appels and colleagues9 used a simpler intervention program involving a relaxation and controlled breathing program following angioplasty. This resulted in a 50 lower risk of further intervention or a new coronary event than that of participants in a no treatment group in the following 18 months.

Sensing Applications Utilizing Rotational Brownian Motion

Rotational Brownian motion for the signal transduction of biochemical binding events. In one of the earliest measurements, the random rotational motion of a wire in a liquid was detected by light reflected from a mirror attached to the wire 9 . Obviously, the detection of rotational Brownian motion for spherical particles is more complicated and requires an anisotropy to break the spherical symmetry. Examples of symmetry-breaking are permanent electric dipole moments, whose motion can be detected with inelastic light scattering 10 , or anisotropic optical properties, which leave a distinct signature of the rotational motion in dynamical light-scattering experiments 11 . Clearly, a permanent magnetic moment will also break the spherical symmetry its use for the detection of rotational Brownian motion is discussed in Section 4.3.2. An alternative approach for the detection of Brownian relaxation is nuclear magnetic resonance, since the relaxation time for nuclear spins is modified by...

Mri Of Atherosclerosis Multi Contrast MRI of Atherosclerosis

The appearance of a thrombus or intraplaque hemorrhage, on MRI, largely depends on the state of hemoglobin contained in the hemorrhage or retained in the thrombus. Depending on the stage of the hemorrhage thrombus it may contain different oxidative and byproduct forms of hemoglobin such as hemosiderin, ferritin, oxyhemoglobin, deoxyhemoglobin, or met-hemoglobin. The different oxidative and byproduct forms of hemoglobin have particular magnetic resonance relaxation parameters that give them different signal intensities due to differences in their T1 and T2 (51-55). The progression of hemorrhage and subsequent thrombus and its appearance on MRI has been

Structures of CS Proteoglycans

The mobility of the various components of cartilage may be investigated by 13C NMR relaxation times. Comparison of isolated chondroitin and its monosaccharides with whole cartilage samples has shown that the carbohydrate component of cartilage retains mobility, whereas the protein components remain relatively rigid (Huster et al., 2002 Naji et al., 2000).

The parasympathetic system

The parasympathetic nervous system is also controlled by the hypothalamus and is related to the activity of the pituitary-adrenal system. However, it is concerned with maintenance activity within the body. Thus digestion is aided by the production of saliva and the digestive enzymes, and peristalsis is maintained. The heart rate is reduced and the respiratory system also decreases in activity. The tissue-repair processes are stimulated and sugars are converted to fats and stored. The body enters a restful, peaceful stage. Sleep is easier during this phase and after a heavy meal the parasympathetic system is very active. The overall effect then is one of muscular and mental relaxation, while the restorative functions take place.

Calcium Transport Ca2ATPase

Calcium, an ion acting as a cellular signal in virtually all cells (see Chapter 34), plays a special role in muscles. It is the signal that stimulates muscles to contract (Chapter 17). In the resting state, the levels of Ca2+ near the muscle fibers are very low (approximately 0.1 M), and nearly all of the calcium ion in muscles is sequestered inside a complex network of vesicles called the sarcoplasmic reticulum, or SR (see Figure 17.2). Nerve impulses induce the sarcoplasmic reticulum membrane to quickly release large amounts of Ca2+, with cytosolic levels rising to approximately 10 M. At these levels, Ca2+ stimulates contraction. Relaxation of the muscle requires that cytosolic Ca2+ levels be reduced to their resting levels. This is accomplished by an ATP-driven Ca2+ transport protein known as the Ca2+-ATPase. This enzyme is the most abundant protein in the SR membrane, accounting for 70 to 80 of the SR protein. Ca2+-ATPase bears many similarities to the Na+,K+-ATPase. It has an...

The Saltsjobaden Program A Model of Cardiac Rehabilitation for Women

At the Saltsjobaden rehabilitation center (Sweden) we provide a CR service designed for women. This program, aiming at promoting and maintaining lifestyle changes, commences with a 2-week inpatient residential course participants then return to the center 2 months later for 5 days, and subsequently for 2 days two times yearly over the next 5 years. The groups contain 6-10 mainly younger women with established CHD. The residential course contains theoretical lectures, discussions, and different physical activities. Relatives are invited to join over a weekend. The psychosocial rehabilitation is based on an interactive, self-instructional program called Stress as an Opportunity, which involves self-assessments concerning different causes of stress, a book on measures to combat stress,homework cards, and a tape with information on stress and relaxation techniques.27 The program consists of three phases a diagnostic phase, an educational phase, intervention and secondary prevention...

Inferior Vena Cava Filters

Used form of mechanical circulatory assistance (Webster, 1988 Sabiston, 1991). It operates on the principle of counterpulsation pressure pulses are cyclically applied from an external pressure source, out of phase with the heart's systolic pulses. The primary objectives are to reduce the workload of the abnormal heart and to increase coronary artery perfusion. The device consists of a cylindrical poiyurethane balloon that is placed in the descending thoracic aorta by way of a femoral artery and connected by a catheter to an external cyclical pump (Fig. 8). The balloon is rapidly inflated during diastole (the period of relaxation and dilatation of the heart) in order to pump blood both up and down the aorta from the site of the device. The

Interventricular Delay

Mitral Regurgitation Wigger

Events of the cardiac electrical cycle. Atrial contraction followed by relaxation produces a negative pressure gradient, causing a surge of blood in the LV at end diastole. Reversal of the atrioventricular pressure gradient initiates mitral valve (MV) closure because of a rapid decrease in pressure between the MV cusps pulling them into apposition. A brief period of isovolumetric contraction exists after MV closure and before AV opening during which the maximal rate of pressure change (peak + dP dt) occurs. Rapid ejection occurs during ventricular systole and is terminated when ventricular pressure falls below aortic pressure, closing the aortic valve (AV). A brief period of isovolu-mic relaxation follows during which the maximal rate of pressure decline (peak - dP dt) occurs. As the left ventricular (LV) pressure continues to decline and fall below atrial pressure, the MV opens and diastolic ventricular filling begins. Normal diastolic filling is characterized by an...

Ffyy ffzz3cos2 0B1B2ayy 1

In two pairs of nuclei A1-A2 and B1-B2, projection angle-dependent cross-correlated relaxation rates due to two dipolar couplings A 2 B1B2 of double and zero quantum coherences between nuclei A1 and B1 can be measured provided the following three requirements are fulfilled (i) The desired double and zero quantum coherence between nuclei A1 and B1 can be excited. (ii) There is a resolvable scalar coupling between A1 and A2 as well as between B1 and B2. For CSA DD cross-correlated relaxation there is no need for the A1, A2 coupling. (iii) The main relaxation source for single-quantum coherence of A1 (SQC) is the dipolar coupling to A2, and the main relaxation source of the SQC of B1 is the dipolar coupling to B2. Again, for CSA DD, the requirement for the A1 and A2 relaxation is void. To illustrate how cross-correlated relaxation can be used to measure the angle between two bond vectors, we will use the example of the generation of double and zero quantum coherence between spins A1 and...

Variations in myocardial perfusion

Coronary Flow And Aortic Pressure

Blood supply to the heart is affected by ventricular contraction and relaxation. Any myocardial stress is expected to alter underlying myocardial geometry and, in turn, geometry of intramyocardial vessels. This may affect Isolated coronary venules dilate in response to an increase in flow.147 This flow-induced vasodilation is endothelium-dependent and mediated by the release of a nitrovasodilator. Endothelial disruption results in flow-induced constriction, suggesting that shear stress may directly act on the vascular smooth muscle.147 Whereas the additive effects of flow-induced dilatation and possibly myogenic relaxation of arterioles can maximise myocardial oxygen delivery during elevated the flow-induced venular dilatation may possibly

Mri Characterization Of Cereal Crops In The Field

The technique can be illustrated by a recent comparison of the effect of osmotic stress on maize and pearl millet plants, which show very different drought tolerances (4). In this study, osmotic stress was induced in 4-week-old cultured maize and pearl millet plants by replacing normal root medium with well-aerated PEG-6000. Some NMR images of a 2.5-mm slice across the stem were acquired at regular time intervals. This was done using a multiple spinecho imaging sequence with a recycle delay of 1.8 s, an echo time of 4.3 ms, with 48 echoes per echo train, resulting in a 48 X 128 X 128 matrix of complex data. Two-dimensional maps or images of the water proton transverse relaxation time, T2, across the stem were then calculated on a pixel-by-pixel basis, together with proton density maps, obtained by extrapolating the echo decays to zero time. Along with the NMR measurements, the time course of water uptake was measured over a 30-hour period by weighing the root medium vessel outside the...

Mass Transfer Models

According to the polymer literature, mass transfer can be classified according to the governing mechanisms into three basic categories zero order, case I, and case II (51). Zero-order transport, termed constant-rate drying, refers to the case where the moisture content varies linearly with time, such as during the initial stages of drying, when the rate of moisture removal at the surface is equal to the rate of moisture transport to the surface. Zero-order transport is generally observed only during the initial stages of drying. Case I diffusion is characterized by a falling rate of moisture transport and is governed by Fick's law and Luikov's model. Luikov's model accounts for Soret and Dufour effects. Case II diffusion describes the case where material relaxation is important in moisture transport. Case II diffusion has been the subject of much research in the polymer field (5254) and has application to moisture transport in foods. Achanta et al. (55) developed a mechanistic model,...

Changes in ventricular performance related to ageing

On consideration of the high prevalence of clinically latent coronary artery disease and hypertension in elderly people, it is not easy to separate the effects of ageing from other pathological processes, and this may well explain some of the variations in the published data.122 Ageing is associated with increasing stiffness of the great arteries, which in turn leads to increases in arterial pulse wave velocity and pulse wave amplitude. The ejection of stroke volume into a stiffer arterial tree and the accelerated reflected pulse waves returning before the aortic valve closure result in higher systolic pressures.123 Thus, there is an increase in left ventricular systolic load manifesting itself as alterations in aortic input impedance. The characteristic impedance increases, there is increased fluctuation of the impedance moduli about the mean, and both the minimum modulus and the pressure-flow phase crossover shift to higher frequencies. The zero frequency impedance modulus,...

Isolated carpal dislocations

Carpal Dislocations

As for most dislocations, an attempt at reduction requires a sufficient amount of muscle relaxation. Ten pounds of traction is applied with finger traps to further fatigue the forearm musculature. The thumb of the dominant hand is placed over the volar aspect of the radius and moved distally until resting on the proximal pole of the scaphoid. The finger traps are then removed and traction is maintained by the opposite hand. A dorsally directed pressure is applied to the proximal pole of the scaphoid as the wrist is ulnarly deviated. With this maneuver a reduction of the scaphoid is usually achieved.