Relaxation Techniques

Relax Your Mind

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The author has done a thorough research even about the obscure and minor details related to the subject area. And also facts weren’t just dumped, but presented in an interesting manner.

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Mechanism of cardiac muscle contraction and relaxation

The myosin heads interact with the actin filaments in cross-bridge cycling, with repetitive attachment and reattachment. The Z lines are drawn closer together, with shortening of the sarcomere. The degree of shortening of the sarcomere is dependent on its initial length, providing an explanation for the Frank-Starling law, whereby the contractility of the heart increases with ventricular preload. Relaxation is brought about by active reuptake of calcium from the cytosol into the sarcoplasmic reticulum. This is achieved by the sarcoplasmic reticulum calcium ATPase pump SERCA2a, which couples the hydrolysis of ATP to active transport of calcium. This cation pump cycles between a number of defined states, including calcium ion binding, ATP binding and phosphorylation, ion release, dephosphorylation and back to ion binding. It is a ten transmembrane-span helix with two cytoplasmic domains. Regulation of the calcium pump activity is modulated by an intrinsic sarcoplasmic reticulum protein,...

Events Underlying Contraction and Relaxation B

Phosphodiesterase Inhibitors Heart

The trigger signal for relaxation is the return of the membrane potential to its resting level. During repolarization, Ca2+ levels fall below the threshold for activation of the myofilaments (3x10-7 M), as the plasmalemmal binding sites regain their binding capacity the SR pumps Ca2+ into its interior and Ca2+ that entered the cytosol during systole is again extruded by plasmalemmal Ca2+-ATPases with expenditure of energy. In addition, a carrier (antiporter), utilizing the transmembrane Na+ gradient as energy source, transports Ca2+ out of the cell in exchange for Na+ moving down its transmembrane gradient (Na+ Ca2+ exchange). B. Processes in myocardial contraction and relaxation B. Processes in myocardial contraction and relaxation

Distances from Dipolar Couplings via Relaxation or Dipolar Recoupling

As indicated in Table 1, dipolar coupling depends on the distance between the two involved spins and is a powerful structural parameter. Imagine the situation of 3, 4, 5, or 6 spins and the possibility to measure all distances between them, namely 3, 6, 10, and 15 distances. Then it is obvious that the 3D structure can be derived just from these internuclear distances since there are 3, 6, 9, and 12 internal coordinates to be determined which are fewer unknowns compared to the number of knowns. Distances are measured in the liquid state NOEs for assignment purposes mostly between protons because they provide the largest dipolar couplings. Due to the overall motion of the protein, the dipolar couplings are stochastically modulated, which leads to the NOE. The stochastic modulation of the dipolar coupling between spins k and l leads to magnetization flow from one nucleus to the next one by the so-called cross-relaxation rate

Multiple Relaxation Model

One way of overcoming the discrepancy between the thermoviscous model and observed power law absorption characteristics of tissues is to use a fitting procedure to Eq. (4.6a), involving either a superposition or distribution of several relaxation time constants (Bamber, 1986 Nachman et al., 1990 Wojcik et al., 1999). This multiple relaxation model corresponds to a tissue model with different, independent, noninteracting molecules, each with its own relaxation constant and associated speed of sound. Typically, two to three relaxation constants are used to fit a measured absorption frequency characteristic for a prescribed frequency range.

Multiple Relaxation Model Wave Equation

One way of overcoming the discrepancy between the thermoviscous model and observed power law absorption characteristics of tissues is to apply a fitting procedure to Eq. (4.6a) involving a superposition of several time constants. As described by Nachman et al. (1990), the multiple relaxation wave equation results in quite complicated expressions for attenuation and phase velocity. At low frequencies, these equations are approximately as follows where constants Kn and time constants tn are associated with each relaxation mode (n). This multiple relaxation model corresponds to the tissue model with different molecules, each with its own relaxation constant and sound speed.

Paramagnetic Relaxation Enhancement

Distance measurement is an essential tool for structure determination from NMR spectroscopy. However, the range of distances that can be observed between protons is limited to 5 A under good conditions 7 A. This is due to the coupling power of two interacting spins that is given by the product of the squares of their gyromagnetic ratios in eqn 2 . By replacing one of the spins by an electron spin, the relaxation can be enhanced over the proton-proton relaxation by a factor of 6602 resulting in an extension of the distances to be accessible by a factor of 6601 3 8.7. Therefore, distances of 30 to 40 A become accessible. Paramagnetic tagging has been successfully used for the characterization of large proteins32 and membrane proteins investigated in micelles33 as well as partially folded proteins in solution.34

Deterministic dynamical systems

Many neuronal models are relaxation oscillators which may be roughly described as follows. Consider a seesaw as shown with a container on one side (A) in which electricity (water) can be held. If the container is empty, the other side (B) of the seesaw touches the ground. From a tap, water is dripping into the container and at a certain water level, point B rises and point A will touch the ground. At this moment the container empties itself, the seesaw bounces quickly back to its original position and the process starts again. Such an oscillation is characterized by intervals of time in which very little happens, followed by short intervals of time in which notable changes take place.

The Hazards of Tobacco

Experts say that you should prepare yourself to quit in advance of smoking your last cigarette. Identify several strategies, such as relaxation exercises, that can help you cope with your cravings for tobacco. First try to establish one or two other new habits, such as regular exercise, so you will be giving up tobacco in the context of a complete lifestyle change. Exercise is important it is the highest predictor of success when quitting tobacco use. When you are ready to quit, take the following steps to ensure success

Background Occupational Lower Back Disorders

Parnianpour et al. 13 , in their study of the fatiguing dynamic movement of the trunk against a set resistance, were the first to report on the combined analysis of triaxial motor output and movement patterns. They showed that during fatiguing trunk flexion and extension, there were significant reductions in the velocity, range of motion, and total angular excursion in the intended (sagittal) plane of motion, and a significant increase in the range of motion and total angular excursion in the accessory (coronal and transverse) planes. The presence of more unintended motion in the accessory planes indicates a loss of coordination and more injury-prone loading conditions for the spine. Numerous studies have demonstrated that soft tissues subjected to repetitive loading show creep and stress relaxation behavior because of their viscoelastic properties 14 . Since the internal stability of the spine is maintained by its passive and active structures, there is an even greater need for...

General Aspects Of Assay Design

An enzyme's progress curve (i.e., a plot of product formation or substrate depletion as a function of time see Fig. 3.5.1) consists of four phases that are of interest to the investigator. The duration of the pre-steady-state region is relatively short and is typically followed via rapid-flow or relaxation techniques. Discussion of this region of the progress curve is beyond the scope of this unit, but a review of these techniques has recently appeared (Fierke and Hammes, 1995). The next portion of the curve is the steady-state phase, a longer phase characterized by relatively constant concentrations of each of the individual enzyme forms (e.g., the enzyme-substrate binary complexes). During the third phase of the progress curve the post-steady-state region the levels of these enzyme complexes change rapidly, until the last phase equilibrium has been reached. Each of these phases contains information of use to the investigator. The steady-state portion of the curve typically exists...

Vascular Contractility and Blood Flow

Changes in NO could also alter vascular contractility and blood flow. In the resistant vessels isolated from diabetic patients and animals, the relaxation phase after acetylcho-line stimulation appears to be delayed (134-137). These impaired vascular relaxation can be restored by PKC inhibitors and mimicked by phorbol ester in normal arteries (137). The inhibition of PKC increased mRNA expression of eNOS in aortic endothelial cells (138). We have observed reduced eNOS expression in microvasculature in Zucker fatty rats, which are the model of insulin resistance (33).

Contrast Agent in Magnetic Resonance Imaging

The resolution and sharpness of the magnetic resonance image in body scanning depend on spin-spin relaxation time, which is reduced by paramagnetic materials 37,53 . A mono-sized polymer particle carrying magnetic iron oxide, given orally, can produce a negative black contrast in magnetic resonance imaging, thus eliminating the image of the gastrointestinal track and providing a clearer visualization of the other organs in the abdomen. The particle size varies according to the type of test. Small particle sizes should be used (diameter less than 3 pm) for parenteral use.

Experimental findings in living cells

To study the rheology of cytoskeletal polymers requires a probe whose operative frequency range spans, insofar as possible, the internal molecular time scales of the rate processes in question. The expectation from such measurements is that the rheological behavior changes at characteristic relaxation frequencies, which in turn can be interpreted as the signature of underlying molecular interactions that dominate the response (Hill, 1965 Kawai and Brandt, 1980). Much of what follows in this chapter is an attempt to explain the failure to find such characteristic relaxation times in most cell types. The experimental findings of our laboratory, summarized below, are derived from single cell measurements using magnetic twisting cytometry (MTC) with optical detection of bead motion. Using this method, we were able to apply probing frequencies ranging from 0.01 Hz to 1 kHz. As shown by supporting evidence, these findings are not peculiar to the method rather they are consistent with those...

Stress Management And Psychiatric Interventions

Stress management techniques such as relaxation training, cognitive restructuring, and coping skills training may reduce negative mood states in HIV-positive persons by lowering physical tension and increasing self-efficacy (Antoni, 2003a). These affective changes are thought to be accompanied by an improved ability to regulate peripheral catecholamines and cortisol via decreases in ANS activation and improved regulation of the HPA axis, respectively. Neuroendocrine regulation may be associated with a partial normalization of immune system functions, providing more efficient surveillance of pathogens such as latent viruses that may increase HIV replication and enhance vulnerability to opportunistic infections or neoplasias. This normalization of stress-associated immune system decrements may ultimately forestall increases in viral load and the manifestation of clinical symptoms over extended periods. A relatively small number of controlled trials have examined the effects of...

Physiological Background

Einthoven Triangle

The pumping function of the heart is the result of a rhythmic cycle of contraction and relaxation of about 1010 muscle cells, a process that is controlled by a complex pattern of electrical activation. Electrical activity is essential for the function of the heart, and many heart problems are closely linked to disturbances of the electrical activity. In fact, most serious heart problems either result from, or cause, abnormalities in the electrical activity.

Nonrelaxing Puborectalis Syndrome Anismus

The constellation of symptoms associated with rectoceles (prolonged repeated straining at bowel movements, sensation of incomplete evacuation, and the need for digital manipulation) is also seen in puborectalis syndrome. Synonyms include nonrelaxing puborectalis syndrome,par-adoxical puborectalis syndrome, spastic pelvic floor syndrome, and anismus. During normal evacuation, distention of the rectum by fecal matter induces relaxation of the internal anal sphincter, followed by contraction of the external anal sphincter mechanism. At the time of defecation, the external sphincter relaxes, as does the puborectalis muscle. This has the effect of straightening the anorectal angle, thereby facilitating elimination. The failure of the puborectalis muscle to relax (or paradoxically, to contract) in nonrelaxing puborectalis syndrome results in continued maintenance of the anorectal angle. The effect is anal outlet obstruction.

Molecular Dynamics in Alternative Ensembles

The simplest method that keeps the temperature of a system constant during an MD simulation is to rescale the velocities at each time step by a factor of (T0 T)1 2, where T is the current instantaneous temperature defined in Eq. (24) and T0 is the desired temperature. This method is commonly used in the equilibration phase of many MD simulations and has also been suggested as a means of performing ''constant temperature molecular dynamics'' 22 . A further refinement of the velocity-rescaling approach was proposed by Berendsen et al. 24 , who used velocity rescaling to couple the system to a heat bath at a temperature T0. Since heat coupling has a characteristic relaxation time, each velocity v is scaled by a factor X, defined as In this expression, At is the size of the integration time step, tt is a characteristic relaxation time, and T is the instantaneous temperature. In the simulation of water, they found a relaxation time of tt 0.4 ps to be appropriate. However, this method does...

Studies of Exposure Therapy

A number of programs based on exposure therapy has been used to treat PTSD. Among the variations of exposure therapy, the PE protocol has been the most extensively studied and has been found to be highly effective. Like PE, some other exposure therapy programs include both imaginal confrontation with the traumatic memories and in vivo exposure to trauma reminders (e.g., Marks, Lovell, Noshirvani, Livanou, & Thrasher, 1998), however, some programs rely exclusively on imaginal exposure to the trauma memory (Bryant et al., 2003a Cloitre, Koenen, Cohen, & Han, 2002 Tarrier et al., 1999). Even among programs that include both imaginal and in vivo exposure, there are differences in the specific application of the techniques. For example, PE utilizes both components from the beginning of treatment in contrast, Marks et al. (1998) introduced imaginal exposure in the first half of the program and in vivo exposure in later sessions. Finally, exposure therapy programs differ in the extent to...

Primary Nursing Diagnosis

Initially, the most important nursing interventions concentrate on pain management. Teach relaxation techniques, diversional activities, and position changes. Help promote the passage of renal calculi. Encourage the patient to walk, if possible. Offer the patient fruit juices to help acidify the urine. Teach the patient the importance of proper diet to help avoid a recurrence of the renal calculi, with particular emphasis on adequate hydration and avoiding excessive salt and protein intake.

Variations on a Theme Studies of Other Exposure Protocols

Several recent studies compared exposure therapy protocols other than PE with alternative CBT interventions. Marks et al. (1998) compared exposure, CR, and their combination with a relaxation control group. Like PE, the exposure therapy used in this study included imaginal and in vivo exercises. However, whereas the two modalities are administered simultaneously in PE, the program examined by Marks et al. (1998) presented the modalities sequentially the first five sessions were limited to imaginal exposure and corresponding homework, and the remaining five sessions focused on in-ses-sion, therapist-assisted in vivo exposure and corresponding homework. Immediately after treatment, the exposure, cognitive, and combined interventions were superior to relaxation, and they retained their superiority at follow-up. Comparisons among the three interventions failed to reveal any consistent pattern of superior performance for one treatment over the others. Notably, like the Foa et al. (2002a)...

Studies in MS and Other Conditions

In MS, biofeedback may be beneficial by promoting relaxation. It also may be helpful in treating some types of pain, including tension headaches, migraines, and low back pain. However, the use of biofeedback to treat MS-associated pain has not been formally studied. An interesting issue is whether biofeedback may be used to regulate the immune system and, conceivably, thereby alter immune diseases such as MS. Variable effects of biofeedback-induced relaxation on immune function have been obtained no consistent results have been reported.

Discharge And Home Healthcare Guidelines

Hypertrophic cardiomyopathy (HCM), also known as hypertrophic obstructive cardiomy-opathy or idiopathic hypertrophic subaortic stenosis, consists of ventricular hypertrophy, rapid contraction of the left ventricle, and impaired relaxation. It is commonly the result of hypertension or valvular heart disease. The process may go on for years with no or slowly progressive symptoms, or the first sign of the disease may be sudden cardiac death. Although the patient may live a normal life, deterioration usually occurs. The third form of cardiomyopathy, restricted cardiomyopathy, is the least common form. Both ventricles become rigid, which distorts the filling phase of the heart. The contraction phase remains normal. The result is that ventricular walls become fibrotic, cardiac filling diminishes, and cardiac output decreases. Restricted cardiomyopathy has a poor prognosis many patients die within 1 to 2 years after diagnosis.

Uptake of the Microvascular Filtrate by the Lymphatic Capillaries

The interstitial fluid may be assumed to flow due to a hydrostatic pressure gradient from the interstitial space with a high fluid pressure into the terminal lymphatics with a lower intravascular pressure. The pressure in cardiac terminal lymphatics is not known. The uptake of the interstitial fluid by the terminal lymphatics is readily explained, however, by their structure and the periodic cardiac contraction muscular contraction compresses the terminal lymphatics and pushes the lymph centripetally, whereas closure of the interendothelial clefts of the terminal lymphatics prevents backflow of the lymph into the interstitium during muscular relaxation, the interendothelial clefts are pulled open by the anchoring filaments and interstitial fluid is sucked into the lymphatic capillaries.55 Furthermore, the endothelial cells of the terminal lymphatics in the heart show plasmalemmal vesicles,56 which may additionally contribute to the lymphatic uptake of interstitial fluid and proteins.

Determinants of venous return to the heart

Inotropic state of the heart, with the effect of ventricular contraction and relaxation. The ventricles exert a suction effect with diastolic relaxation. Blood is drawn into the atria during ventricular systole due to descent of atrio-ventricular fibrous rings. Venomotor tone.

Myocardial Contractions

The main force of cardiac lymph propulsion is undoubtedly the myocardial contraction. During systole, the myocardium is squeezed and the lymph is propelled to the superficial lymphatic trunks and forced to flow away from the heart. Accordingly, recent studies have shown a significant decrease in cardiac lymph flow following cardiac arrest during cardiopul-monary bypass.57,58 During cardiac relaxation, the epicardial surface of the heart and the superficial lymphatic trunks are pressed against the pericardium and lymph is propelled away from the heart due to the valves of the lymphatic vessels. The subendo- to subepicardial gradient of intramyocardial pressure, which is present at least during systole, can be assumed also to promote lymph flow within the lymphatic capillary network of the ventricular wall.

Frequency dependence of g and g

This behavior was at first disappointing because no characteristic time scale was evident we were unable to identify a dominating relaxation process. The only characteristic time scale that falls out of the data is that associated with curvilinearity of the G data that becomes apparent in the neighborhood of 100 Hz (Fig. 3-4). As shown below, this curvilinearity is attributable to a small additive Newtonian viscosity that is entirely uncoupled from cytoskeletal dynamics. This additive viscosity is on the order of 1 Pa s, or about 1000-fold higher than that of water, and contributes to the energy dissipation (or friction) only above 100 Hz. Below 100 Hz, friction (G ) remained a

Potential Pitfalls and Tips

Catheter to the anal wall or by stool particles. Often, a slight adjustment of the catheter will solve this problem. A lengthy investigation can modify pressures by the accumulation of water in the rectum. Eliciting the rectonal inhibitory reflex is sometimes difficult or impossible due to the rapid distention of the rectal wall, such as in patients with megarectum. Instead of eliciting the reflex, the too slow inflation will lead to repetitive relaxation of the internal anal sphincter.

Developmental control of tooth shape

The second problem is that in most molar teeth, the primary knot is long gone by the time the last secondary knots appear and cusps form (Figure 2.4). A primary knot-centric model on tooth morphogenesis would thus predict that the cusp patterns are determined early during morphogenesis. This could also mean an increasing relaxation in the control of later developing cusps. This, of course, usually means the smallest cusps, and while it is generally known that small cusps tend to be variable in number, it is not really known if this is a result of increasing variability in the later developing cusps. A second possibility is that the secondary enamel knots affect the formation of each other. This could be via signalling molecules (e.g. Fgf-4), and each secondary

Biological Correlates Of Acute Posttrauma Predictors Of Chronic Symptom Development

Basic science research on memory consolidation and fear conditioning during states of heightened arousal (i.e., adrenergic activation) is consistent with the idea that peri-traumatic panic, or even intense distress during and immediately after a traumatic event, might contribute to the production of intrusive recollections. However, clarifying the precise nature and biological correlates of symptoms that appear in the immediate aftermath of a trauma, and or that predict the continued presence of long-term symptoms, will no doubt assist in developing models for potential prophylactic interventions and early treatments. For example, to the extent that panic reactions are associated with increased catecholamine responses at the time of trauma, early and aggressive intervention with adrenergic blocking agents 26 , or cognitive-behavioral stress management techniques emphasizing relaxation, may be the most appropriate interventions for persons who panic in the hours immediately following...

Hirschsprungs Disease

Hirschsprung's disease is a rare congenital abnormality with an incidence of 1 in 5000 births, resulting in distal obstruction. The inadequate motility is due to aganglionosis, resulting in megacolon. Anorectal manometry is an important test in these situations, as the evaluation of the rectoanal reflex is simple and easily obtained. In these patients, the normal internal sphincter relaxation is not present in response to rectal distention, which strongly indicates Hirschsprung's disease.3536

Physical and Emotional Health How They Interact

There has been a recent surge of interest in the mind body connection by physicians to see if positive health effects can be obtained from relaxation techniques such as meditation. The increasing complexity and pace of life and the awareness that long-term stress has a negative physiological effect on the body have triggered the exploration of relaxation techniques. By combining knowledge of meditative techniques from Eastern cultures with Western scientific techniques, doctors have developed a form of meditation that may have positive effects on blood pressure and heart disease. Meditation appears to lower metabolism decreasing breathing rate, heart rate, and blood pressure. An understanding of the connection between the mind and the body becomes clearer as new techniques are found to examine and to measure the nervous system's subtle control over changes in the circulatory system. The positive response of the circulatory system to a variety of relaxation techniques, such as...

Esophageal Spasm Syndromes

Diffuse esophageal spasm results from hypertrophy of the mucsular layers and degeneration of the vagus. Manometry reveals multiple simultaneous or uncoordinated contractions. The lower esophageal sphincter (LES) will have short duration of relaxation and 20 of the distal esophagus will demonstrate simultaneous contractions. Hypertensive lower esophageal sphincter is associated with normal esophageal perstalsis but with delayed passage of food bolus through the gastroesophageal junction. The LES pressure is 26 mm Hg with relaxation pressures

Choice of Sampling Scheme

Isothermal simulations (molecular dynamics or Monte Carlo) provide characteristics of the system's properties at a single temperature. Numerous simulations at various temperatures (above and below the folding transition temperature) are needed to gain some insight into the thermodynamics of the folding process. There is a very serious problem associated with the extremely slow relaxation of protein models in the dense globular state. The local barriers in the energy landscape near the folded state are high and the sampling becomes ineffective. Thus the computer studies employing straightforward MD or canonical MC algorithms became prohibitively expensive. Essentially, the same applies to various simulated annealing strategies. In all cases, the design of sampling details could be very important. For example, properly designed local moves can jump over'' the high local energy barriers, thereby speeding up the sampling of the entire conformational space.

Endothelium Dependent Vasodilatation

Both ACE inhibition and ATI receptor antagonism improves acetylcholine-induced vasorelaxation in NIDDM subjects (127,128). Treatment of normotensive type 1 diabetics with an ACE inhibitor has also been shown to increase acetylcholine-induced vasorelaxation in (129,130). In these studies, no difference in vasodilatation induced by NO donors (sodium nitroprusside) was observed in diabetic vs control subjects, suggesting that the endothelium dysfunction was related to impairment in the generation of NO rather than an impaired response potential. ACE inhibition may improve endothelium-dependent relaxation by suppressing Ang II effects on vascular NADH NADPH oxidase production of superoxide anions and or vascular insulin signaling (131-133). Although ACE inhibition improves endothelium-dependent vasorelaxation induced by acute aceylcholine infusion (127,130) it did not improve endothelial function in response to flow-mediated dilation (134,135). Therefore, ACE inhibition appears to...

Cognitivebehavioral Interventions

Exposure techniques have also been applied to persons suffering from post-traumatic disorders. They use careful, repeated, detailed imagining of the trauma (exposure) in a safe, controlled context to help the survivor face and gain control of the anxiety, fear and distress that was overwhelming during the disrupting event. In some cases memories or reminders can be confronted all at once (''flooding''). For other individuals, it is preferable to work up to the most severe symptoms gradually by using relaxation techniques and by starting with less upsetting life stresses, or by taking the trauma one piece at a time (''desensitization''). Systematic desensitization involves the pairing of relaxation with either stimuli reminiscent of the traumatic event (''in vivo'' desensitization) or images of the disrupting event (imaginal desensitization). In vivo exposure to traumatic cues would include a return to the scene of a disruptive event and a gradual approach to the cues that are most...

Magnetic Resonance Imaging

Magnetic resonance has been applied successfully to medical imaging of the body because of its high water content. The hydrogen atoms in water (H2O) and fat make up 63 of the body by weight. Because there is a proton in the nucleus of each hydrogen atom, a small magnetic field or moment is created as the nucleus spins. When hydrogen is placed in a large static magnetic field, the magnetic moment of the atom spins around it like a tiny gyroscope at the Larmor frequency, which is a unique property of the material. For imaging, a radiofrequency rotating field in a plane perpendicular to the static field is needed. The frequency of this field is identical to the Larmor frequency. Once the atom is excited, the applied field is shut off and the original magnetic moment decays to equilibrium and emits a signal. This voltage signal is detected by coils, and two relaxation constants are sensed. The longitudinal magnetization constant, T1, is more sensitive to the thrermal properties of tissue....

Genesis of Hand Preference

Many cultures discourage the use of the left hand. Even in the United States and England, countries that are noted for their tolerance of diversity, the scientific term for left-handedness is sinistral, which means evil. In many other languages the terms used for left-handedness also have negative connotations. In the United States, children who write with their left hand are no longer trained to switch hands and to write with their nonpreferred right hand, but only a few generations ago this was a widespread practice. Despite the relaxation of cultural pressure in the United States, the percentage of people who are right handed has remained about 90 . Thus, although cultural factors might influence the overall prevalence of hand preference, cultural influences do not appear to play a critical role.

Benign Hepatic Tumors

On CT, hemangiomas are sharply defined, hypodense masses compared to the adjacent hepatic parenchyma on unenhanced images. They have a distinctive enhancement pattern characterized by sequential contrast opacification beginning at the periphery as one or more nodular or globular areas of enhancement, and proceeding toward the center. The key factor is that all areas of lesion enhancement should appear with the same enhancement as blood pool elsewhere (Fig. 2). MRI is useful in differentiating heman-giomas from malignant hepatic neoplasms, based on very long T2 relaxation of the hemangioma compared with other hepatic masses. Other characteristic MRI features include a sharp margin and internal homogeneity. Similar to CT, key to diagnosis is typically early enhancing peripheral nodular enhancement on dynamic T1 images, with progressive fill-in on delayed images on dynamic gadolinium-enhanced MRI. However, in some cases, hemangiomas may be atypical. With both CT and MRI it is important...

Metabolic derangements that accompany liver failure

Achalasia hypertensive lower esophageal sphincter (LES), ingbr'nplete relaxation of LES, and loss or derangement of peristalsis. Achalasia is usually idi opathic but may be secondary to Chagas' disease (South America). Patients have intermittent dysphagia for solids and liquids with no heartburn. Barium swallow reveals dilated esophagus with distal bird-beak narrowing. Diagnosis can be made with esophageal manometry. Treat with calcium channel blockers, pneumatic balloon dilatation, and, as a last resort, surgery (myotomy).

Electromyography of the Anal Sphincter

Activity in the external anal sphincter (EAS) is different from that in other muscles, as there is continuous and spontaneous EMG activity, even at rest.4 This activity is constantly varied and increases with rectal distention and changes of body positioning. The EMG activity also usually increases during voluntary squeezing of the sphincter muscle, but ceases during relaxation of the EAS during pushing and evacuation.

Algorithms for Combinatorial Search and Optimization

Combinatorial search and optimization methods are well developed and suited to the incorporation of problem-related knowledge in order to find solutions quickly. There are two types of general methods for solving combinatorial problems depending on the strategy used (1) divide-and-conquer methods and (2) relaxation methods. In divide-and-conquer methods, problems are solved by answering subproblems and building up the solution. For example, in the traveling salesman problem, a route for the complete journey could be constructed by adding cities one at a time and taking into account the lengths of these intermediate routes. Well-known search techniques in this class, used in de novo design methods, include the depth-first, branch-and-bound, and A* searches.56 In contrast, in relaxation methods, an initial solution would be proposed and used as a baseline for improvements. In the traveling salesman problem, all cities could be initially visited in a random order to decrease the length...

Dynamic Magnetic Resonance Imaging and Nuclear Imaging

Defecation requires intraabdominal pressure coordinated with relaxation of the anal sphincters and pelvic floor muscles, particularly the puborectalis muscles. Pelvic floor motion can be imaged in real-time by barium fluoroscopy, radioisotope scintigraphy, or magnetic resonance imaging (MRI). Barium evacuation proc-tography was described in separate reports by Burhenne1 in 1964 and Phillips and Edwards2 in 1965. O'Connell et al3 developed scintigraphy to quantify rectal evacuation after ileal pouch anal anastomosis with lesser radiation exposure compared to barium proctography. Dynamic MRI visualizes anorectal and pelvic floor motion during rectal evacuation without radiation exposure.4

What Is The Evidence For Cbts Effectiveness

A potential limitation of these studies is that the inclusion of all recently distressed trauma survivors raises the possibility that treatment effects may overlap with natural recovery in the initial months after trauma exposure. In an attempt to overcome this problem, other studies have focused on people who meet criteria for ASD because of evidence that most people who do display ASD are at high risk for subsequent PTSD (Bryant, 2003). In an initial study of ASD participants, Bryant and colleagues randomly allocated motor vehicle accident or nonsexual assault survivors with ASD to either CBT or SC (Bryant, Harvey, Dang, Sackville, & Basten, 1998b). Both interventions consisted of five 1.5-hour weekly individual therapy sessions. CBT included education about posttraumatic reactions, relaxation training, cognitive restructuring, and imaginal and in vivo exposure to the traumatic event. The SC condition included trauma education and more general problem-solving skills training in the...

Diagnosis of insomnia

Following publication of the ICD-10 diagnostic criteria for insomnia, which are quite similar to those of DSM-IV, the Athens Insomnia Scale (AIS) was developed with the main goal of assisting clinicians in diagnosing insomnia on the basis of ICD-10 33, 34 . However, while the diagnostic criteria concerning time, so that a sleep disturbance may be diagnosed as insomnia, are precise and of clinical value, what is also required is the subjective feeling of discontent 33, 34 . This means that the patient should report dissatisfaction concerning the amount and even the quality of his or her sleep. What is notable is that most people suffering from insomnia say they do not feel refreshed when awakened. Thus, sleep in insomniacs does not fulfill the task of rest and relaxation, for both the body and the mind. In a recent study of a large group of people, representative of seven European countries, about 11 complained of nonrestorative sleep 40 . The complaints concerning nonrestorative sleep...

Treatment of insomnia

Insomnia may be distinguished in two different states. The first is a state of transient insomnia due to an acute event, while the second is the state of chronic insomnia. What is required in the first case is a treatment lasting for a few days only, i.e., for the period of the underlying event that caused insomnia. Such a case requires a medicine able to induce sleep immediately, while its effect quickly diminishes, so that the individual does not experience after effects when awakened. In the case of chronic insomnia, i.e. , when a person cannot relax in order to fall asleep, the therapeutic effort should be aimed at the reduction of chronic stress. The objective is to reduce the level of arousal when going to bed. Thus, the treatment may be more on a psychological basis, employing psychotherapeutic techniques, so that the patient can control the levels of his or her stress. In fact, all psychotherapeutic techniques, ranging from those of a psychoanalytical nature to those of...

Pelvic Muscle Exercise Kegel Exercises

At each stage of treatment, patients are encouraged to practice these exercises daily without instrumentation feedback. While Kegel17 asked patients to perform approximately 300 contractions daily during treatment and 100 during maintenance, there is no known optimal specific number of exercise sets. The goal of Kegel exercises is to facilitate rehabilitation of the pelvic floor muscles to achieve efficient muscle function. This includes normal resting tone, rapid recruitment of the pelvic floor muscles, sustained isolated pelvic muscle contraction, quick release to a normalized resting tone, and appropriate relaxation during defecation or micturation.

Anxiety Management Skills

It can be useful to provide anxiety management strategies early in therapy because (1) they can give patients a degree of control over their distress, and (2) these techniques are relatively simple to use. Be aware that most patients experience considerable distress during the initial sessions because they are confronting and expressing upsetting memories. The utility of reducing arousal in the acute posttrauma phase is also indicated by evidence that acute arousal is associated with chronic PTSD (Shalev et al., 1998). Giving the patient some tools to assist mastery over the acute anxiety can provide both a sense of relief and a motivation to comply with more demanding therapy tasks. Anxiety management often involves progressive muscle relaxation (Ost, 1987) and breathing retraining, which aims to achieve 10 breaths a minute. Although these techniques are simple, therapists need to be aware that focusing on bodily sensation or on breathing can trigger reminders of the trauma. First,...

Anorectal Coordination Maneuver

Patients with symptoms of difficult, infrequent, or incomplete evacuation or those individuals with increased muscle activity while performing the Valsalva maneuver during the initial evaluation are taught the anorectal coordination maneuver. The goal is to produce a coordinated movement that consists of increasing intraabdominal (intrarectal) pressure while simultaneously relaxing the pelvic muscles. During the initial sEMG evaluation of the Valsalva maneuver, patients are asked to bear down or strain as if attempting to evacuate, which may elicit an immediate pelvic muscle contraction and closure of the anorectal outlet (Fig. 13.11). This correlates with symptoms of constipation including excessive straining and incomplete evacuation. The results of the sEMG activity observed on the screen display must first be explained and understood by the patient before awareness and change can occur. Change begins with educating the patient on diaphragmatic breathing, proper positioning, and...

Youth Smoking Cessation

Sussman, Dent, and Lichtman (2000) designed an innovative school quit-smoking program that featured interactive activities, such as games and talk shows, alternative medicine techniques (i.e., yoga, relaxation, and meditation), and behavioral strategies for smoking cessation. Two hundred and fifty-nine students enrolled in the program at 12 schools and another 76 students served as standard care controls (smoking status surveyed at baseline and at 3 months). Objective measures of cigarette smoking were used. Elective class credit and class release time were offered for participation in the program.

Vascular Effects of Estrogens

Vasoregulation occurs as a balance between the release of relaxing and constricting factors. The predominant relaxing factor is nitric oxide (NO), which is synthesized from the amino acid L-arginine. NO release activates SMC guanylate cyclase, leading to increased cyclic guanosine monophosphate production and vascular relaxation (25). Other relaxing factors include prostacyclin and hyperpolarizing factor, which act through cyclic adenosine monophosphate and potassium channels respectively. The major constricting factors are endothelin-1, thromboxane, and prostaglandin H2 (24).

Effects of Estrogen on Endothelial Function

ERT also provides insights into NO regulation by estrogen. Thus, endothelium-depen-dent vasodilation of the branchial and coronary arteries is enhanced after ERT in postmenopausal women and levels of plasma NO and NO metabolites are increased (36,37). It is of interest that inclusion of progesterone in postmenopausal HRT may blunt the effects of estrogen on endothelial NO production (38). Similar effects of enhanced endot-helial function have been observed after ERT in young women with premature ovarian failure or following ovariectomy and in young women receiving oral contraception (33,39). Furthermore, a case has been reported of a young man with nonfunctional ERa as a result of mutation of the ER gene (40). The man was found to have impaired branchial endothelium-dependent relaxation and early coronary calcification supporting the view that ERa is important for endothelial NO release. environment, ultimately leading to eNOS stimulation (43-45). Additional mechanisms for nongenomic...

Subpulmonary Ventricular Septal Defect

Hypoplastic Pulmonary Valve Annulus

Subpulmonary ventricular septal defects are located high in the ventricular septum and immediately below the pulmonary valve. Myocardial relaxation with cardioplegic arrest allows the upper septum to be retracted inferiorly, so that many subpulmonary defects can be closed completely through the transatrial approach. In many cases, an aortic valve cusp is intimate with the rim of this ventricular defect and care must be used to avoid damage to the valve. If exposure through the atrium is not satisfactory, this approach should be aborted and a high small transverse right ventriculotomy or proximal main pulmonary arteriotomy used for the repair. Working through the proximal ascending aorta with retraction of the aortic valve is an alternative repair exposure.

Appearance of Stab Wounds in Skin

Knife Stab Simulations

The size and shape of a stab wound in the skin depends on the nature of the blade and knife, the direction of the thrust, the movement of the blade in the wound, the movement of the individual stabbed, and the state of relaxation or tension of the skin. The sharpness of a weapon will determine the appearance of the margins of the wound sharp and regular abraded and bruised, or jagged and contused. With a blunt cutting edge, the edges of the wound may be abraded. If an individual is stabbed such that the flat surface of the knife blade is at an oblique angle to the skin, the stab wound will have a beveled margin on one side with undermining on the other, indicating the direction from which the knife entered.

Treatment Of Spin Diffusion

From a given structure, the NOE effect can be calculated more realistically by complete relaxation matrix analysis. Instead of considering only the distance between two protons, the complete network of interactions is considered (Fig. 8). Approximately, the Figure 8 Effects of spin diffusion. The NOE between two protons (indicated by the solid line) may be altered by the presence of alternative pathways for the magnetization (dashed lines). The size of the NOE can be calculated for a structure from the experimental mixing time, Tm, and the complete relaxation matrix, (Rj), which is a function of all interproton distances dj and functions describing the motion of the protons. y is the gyromagnetic ratio of the proton, h is the Planck constant, T is the rotational correlation time, and ro is the Larmor frequency of the proton in the magnetic field. The expression for (Rj) is an approximation assuming an internally rigid molecule. Figure 8 Effects of spin diffusion. The NOE between two...

Recent Applications

Molecular modeling is an indispensable tool in the determination of macromolecular structures from NMR data and in the interpretation of the data. Thus, state-of-the-art molecular dynamics simulations can reproduce relaxation data well 9,96 and supply a model of the motion in atomic detail. Qualitative aspects of correlated backbone motions can be understood from NMR structure ensembles 63 . Additional data, in particular residual dipolar couplings, improve the precision and accuracy of NMR structures qualitatively 12 .

Causes of disruption of bloodbrain barrier function

The blood-brain barrier can be bypassed by intrathecal administration of drugs into the CSF and by drug modification (increased lipid solubility carrier transport). Disruption of barrier function can be recognised radiologically on computed tomographic scanning by the phenomenon of contrast enhancement, and is associated with vasogenic cerebral oedema. Disruption is associated with acute increases in CSF protein levels. Loss of integrity of the barrier function is related to partial and reversible relaxation of endothelial tight junctions, and to increased vesicular transport across the endothelial cells.

Physiological Effects

Cannabis intoxication commonly heightens the user's sensitivity to external stimuli, thus making colors seem brighter and smells more pungent. It also distorts, sometimes severely, the user's sense of time. The term temporal disintegration (Mathew, Wilson, Humphreys, Lowe, & Weithe, 1993) has been coined to describe this slowing of subjective time after use of marijuana. In addition, at least in low doses, marijuana causes mild euphoria and feelings of relaxation. It is also know to increase appetite. There is some controversy over whether individuals intoxicated with cannabis pose a hazard, as they seem to be attracted to thrill-seeking behavior and are usually subdued. Some people have argued that individuals who smoke marijuana are less likely to drive fast however, reaction time to complex and unforeseen situations is slowed, and muscle strength and hand-eye coordination is decreased. Because it delays reaction time, alters time perception, and for many other reasons, marijuana...

Diagonal Band Of Broca

Diagonal Band Broca

There is evidence that in smooth muscle the balance between the contracted or relaxed state may depend on the relative activity of the sympathetic or par-asympathetic drive to the muscle. The sympathetic drive to smooth muscle, mediated by the neurotransmitter norepi-nephrine, activates a Gs protein, which activates the enzyme adenylate cyclase. This results in increased cAMP production, and relaxation of the muscle. ACh is released by the parasympathetic nerve terminal and acts on M2 receptors, which activate an inhibitory Gi protein, which in turn moves to and inactivates adenylate cyclase. Thus, synthesis of the second messenger cAMP is inhibited, and this increases muscle contractility. Also, ACh binds to an M3 receptor, which activates a Gq protein, which activates the enzyme phospholipase C (PLC), which in turn activates the IP3 second messenger system, which results in Ca2+ mobilization and increased contractility. A similar balance between noradrenergic and muscarinic inputs...

Preparation Of Dna Fibers From Fibroblasts By The Halo Technique

One of the oldest techniques used for DNA fiber-FISH mapping is called the halo preparation technique (Wiegant et al., 1992), a modified version of the technique described by Vogelstein et al. (1980). Cells growing on a glass slide are lysed in a buffer containing a detergent. This is then followed by high-salt washes to remove histones from the chromatin. The DNA in such nuclei consists of loops anchored to the nuclear matrix in a form having a high degree of negative supercoiling. Next, the nuclei are incubated in a high-salt buffer containing a DNA-intercalating dye to unwind the DNA loops by introducing positive supercoiling. This is then followed by UV irradiation to make nicks, which leads to relaxation of the DNA that has been looped out. Although in principle a true halo of DNA loops of 14 to 16 m can be obtained, for mapping purposes it is advantageous to produce much longer loops.

Diaphragmatic Breathing Physiological Quieting

The breathing cycle is intimately connected to both sympathetic and parasympathetic action of the autonomic nervous system.19 Bowel and bladder function is also mediated by the autonomic nervous system.10 Conscious deep diaphragmatic breathing is one of the best ways to quiet the autonomic nervous system. This breathing effectively initiates a cascade of visceral relaxation responses. The aim of this exercise is to make the shift from thoracic breathing to abdominal breathing.19 Patients are instructed to slowly inhale through the nose while protruding the abdomen outward as if the abdomen is a balloon being inflated or allowing the abdomen to rise. This maneuver is followed by slow exhalation through the mouth as the abdominal balloon deflates or as the abdomen falls. Patients are encouraged to practice this in a slow, rhythmical fashion. Visualization and progressive relaxation techniques in conjunction with diaphragmatic breathing may be used to

Field Effect Transistors FETs

The specific capacitance of an open-gate transistor is small in comparison to the capacitance of a metal electrode. As a consequence, the capacitive current through the transducer can be neglected. This approximation implies that the relaxation of the junction is fast in comparison to the dynamics of the transducer response. It is valid for recordings in the millisecond range 65 .

Depolarizing Muscle Relaxants

Depolarising Muscle Relaxants

In this drug class, only succinylcholine (succinyldicholine, suxamethonium, A) is of clinical importance. Structurally, it can be described as a double ACh molecule. Like ACh, succinylcholine acts as agonist at endplate nicotinic cholino-ceptors, yet it produces muscle relaxation. Unlike ACh, it is not hydrolyzed by acetylcholinesterase. However, it is a substrate of nonspecific plasma cholin-esterase (serum cholinesterase, p. 100). Succinylcholine is degraded more slowly than is ACh and therefore remains in the synaptic cleft for several minutes, causing an endplate depolarization of corresponding duration. This depolarization initially triggers a propagated action potential (AP) in the surrounding muscle cell membrane, leading to contraction of the muscle fiber. After its i.v. injection, fine muscle twitches (fascicu-lations) can be observed. A new AP can be elicited near the endplate only if the membrane has been allowed to repo-larize.

Deterministic Global Optimization

The aBB global optimization approach is based on the convex relaxation of the original nonconvex formulation (1). This requires convex lower bounding of all expressions, and these expressions can be classified as (i) convex terms, (ii) nonconvex terms of special structure, and (iii) nonconvex terms of general structure. Obviously, convex lower bounding functions are not required for original convex expressions (e.g., linear terms). Certain nonconvex terms, including bilinear, trilinear and univariate concave functions, possess special structure that can be exploited in developing lower bounding functions. All other nonconvex terms can be underestimated using a general expression 18 . (iv) The maximum separation between the nonconvex term of generic structure, f (x), and its convex relaxation, f (x), is bounded and also proportional to the positive a parameters and to the square of the diagonal of the current box constraints

And Paraffin Embedded TissueProtocol

In formalin-fixed and paraffin-embedded tissue material, the DNA is trapped in a relatively strong matrix of cross-linked protein. If the tissue material is fixed at neutral pH for not longer than 24 hr, the DNA and proteins are internally cross-linked to a limited extent. This protocol describes such a cross-linking procedure. Incubation in formic acid H2O2 removes protein prior to permeabilization with pepsin, improving nuclear isolation and permeabilization. Following permeabilization, formalin-fixed nuclei are brought to pH 9, resulting in a three-fold increase in nuclear size. Compare this to the pH-driven swelling of fresh nuclei, which uses a change from acidic to neutral pH (see Basic Protocol 2). For formalin-fixed nuclei, a higher pH is needed for relaxation as a result of cross-linking of histone proteins during formalin fixation. The morphology of the nuclei isolated by this protocol will resemble that of methanol acetic acid-fixed cells with respect to size and efficiency...

Intestinal Permeability Is Increased In Bronchial Asthma

Pathophysiology Tonic Clonic Seizures

IgE-mediated allergic reactions (p. 72) involve mast cell release of histamine (p. 114) and production of other mediators (such as leukotrienes, p. 196). Resultant responses include relaxation of vascular smooth muscle, as evidenced locally by vasodilation (e.g., conjunctival congestion) or systemically by hypotension (as in anaphylactic shock) enhanced capillary permeability with transudation of fluid into tissues swelling of conjunctiva and mucous membranes of the upper airways ( hay fever ), cutaneous wheal formation contraction of bronchial smooth muscle bronchial asthma stimulation of intestinal smooth muscle diarrhea.

Early Subacute Hematoma

Hematoma Edema

In the early stage of the subacute hematoma (Figs. 6.2 and 6.3), there is a decline in the energy state of the red blood cell and hemoglobin is oxidized to met-he-moglobin 3,4,7,10,11,14,19,22,23,28-30, 33, 34 . In met-hemoglobin the iron is still bound to the heme moiety within the globin protein, but it is now in the ferric state with five unpaired electrons. This transformation normally starts in the periphery of the hemorrhage and gradually evolves to the center. In the transition to met-hemoglobin, conformational changes will take place in the molecule and water protons will now have access to the unpaired electrons of iron in met-hemoglobin, creating a proton-electron, dipole-dipole interaction. Dipolar relaxation enhancement will then take place, making met-hemoglobin appear hyperintense on T1-weight-ed images. Met-hemoglobin, as a paramagnetic sub stance, will induce magnetic susceptibility relaxation affecting the transverse relaxation (T2* effect), which results in a marked...

Pharmacologic Highlights

One of the most life-threatening complications of liver failure is airway compromise because of neurological or respiratory deterioration. Keep endotracheal intubation equipment and an oral airway at the bedside at all times. Elevate the head of the patient's bed to 30 degrees to ease respirations, and support the patient's arms on pillows to decrease the work of breathing. It is essential to be at the bedside and to perform serial assessments of all critical systems. Space all activities and limit visitors as needed so that the patient gets adequate rest. To encourage rest, consider nonpharmacologic methods such as diversionary activities and relaxation techniques.

Practical Information

Meditation may be done independently by following techniques described in books such as The Relaxation Response. Classes in meditation techniques often are available through hospitals, health clubs, and community centers. Individual classes are typically 30 to 90 minutes in length and cost 60 to 150 per session. Group sessions are 60 minutes and cost 15 to 35. If meditation is pursued, it is important to keep in mind that it often does not have immediate effects. It may take several weeks or months of practice to achieve significant relaxation.

Determination of Macroscopic Voltage Sensitivity

When small transjunctional voltage steps are applied to gap junctions, their conductance is rather constant in time. However, upon larger voltage steps, most gap junctions exhibit voltage sensitivity, and tend to decrease their conductance, which is seen as a relaxation of the junctional current as shown in Fig. 2A. At the start of the 100 mV command voltage step on a computer-simulated cell pair, containing six connexin43 (Cx43) gap junction channels, an instantaneous current Ij,0 is seen in the nonstepped cell, which strongly diminishes during the 2-s step, reaching a quasi-steady-state value (Ij, ) within 1-2 s. A common way to present and quantify voltage-dependent parameters of gap junctions is by plotting all the Gj values, normalized for the junctional conductance measured at a small voltage step (e.g., 10 mV), for voltage steps from, for example, -100 to 100 mV as presented in Fig. 2B. The data are fitted to a Boltzmann equation (2,3)

Effects of stimulation of adrenergic receptors

Arteriolar and venular constriction Iris dilatation Intestinal relaxation The cardiac positive inotropic effects result from increased calcium concentration due to phosphorylation of L-type calcium channels and phosphorylation of sarcolemmal calcium pumps. Beta 2 Vasodilatation Intestinal relaxation Uterine relaxation Bronchodilatation Calorigenesis Bladder wall relaxation

Evolution of the Enteric Nervous System

Laminin promotes neuritic extension and axonal growth.16 Laminin 1 promotes development of neurons from enteric cells of neural crest cells. There is a histologic difference between aganglionosis and denervation. An aganglionic segment is not den-ervated what are missing are the cell bodies of the enteric neurons, which mediate the reflexes. An aganglionic segment may be hypernervated, and this is seen in HD, wherein an abundance of laminin 1 is seen. The ENS is essential for normal propulsive intestinal motility. The peristaltic reflex has long been recognized as one that is evoked by increased luminal pressure and results in a wave of excitation and relaxation that descends the bowel and is propulsive however, its net effect is as a relaxant. This feature accounts for the contraction and narrowing that occurs in the hypoganglionic segment of bowel.

Deterioration Of Arterial Function With Aging

The effect of age on endothelium-mediated responses varies with species and vascular bed.10 In general, there is a tendency toward a reduction in endothelium-dependent relaxations.9 In contrast, relaxation of aged vessels in response to nitrovasodilators is essentially well maintained1112 although contradictory results have also been published.13 The reduction in endothelium-dependent vasodilations of aged arteries may be contributed to by a decrease in the synthesis of NO. It has also been suggested that the reduction could be due to an inhibition of NO access to smooth muscle cells by the thickening of endothelial and smooth muscle layers in aging.9 Changes also take place with aging in the endothelium-independent vasodilations. The relaxation caused by the -adrenoceptor agonist isoprenaline is especially reduced during aging.914 A reduction in -adrenergic responses during aging is a very common phenomenon.15 The reduction in -receptor-mediated responses in the arteries reduces the...

Variability in Ventricular Wall Motion Pattern

Heart Wall Segments Diagram

There are only weak discriminations between normal and hypokinetic ventricular wall motion unless verified by functional stress tests. If one is familiar with it, the left ventricular pressure-dimension loop may best and easiest inform about the actual functional state of the ventricular wall segment under study.21,22 It is mentioned that there are some peculiarities in the shape of the pressure-length loop which might indicate an acute ischemic insult (Fig. 5.2). Depending on the site and layer where the ultrasonic transducers are implanted, the recorded tracing may show conformational changes of the ventricle which appear as length changes during the isovolumic contraction and relaxation. Pronounced regional wall shortening during isovolumic ventricular relaxation (postsystolic shortening (PSS)) also has been observed in the acutely ischemic myocardium and has been identified to be a predictor of the early and late recovery of function after coronary artery reperfusion.23 In...

Molecular Weight Considerations

The linewidth obtained is directly proportional to the square of the relevant anisotropic interaction multiplied with the correlation time. Some relevant interactions are given in Table 1 and have been indicated in Figure 7. The quadratic dependence of the line width G from the interaction size bk originates from the Bloembergen and Redfield relaxation theory. The double commutator of the respective interactions Alu(Ik, 7 ) multiplied with the spectral density function J(raq) determines the linewidth12,13 For liquid-state NMR proton detection is compromised by the fast relaxation of transverse magnetization of the 1H,13C and 1H,15N dipolar couplings. Due to interference of different relaxation mechanisms or the inefficiency of relaxation mechanisms for certain coherences it is possible to obtain narrow linewidths even for large molecules with long correlation times.15 These so-called relaxation optimized sequences rely on the choice of coherence that relaxes the slowest during a...

Glissandothe Court Jester Bisexual Brouhaha

An analyst approaching this material from a classical perspective might hypothesize that the patient's new feeling of masculine, identificatory closeness may have stimulated homosexual fantasies, anxieties, and defenses. Although fervently desired, greater relaxation, openness, and emotionality might simultaneously have made the analysand feel more feminine a vulnerable position to be in with a potentially crazy analyst.

Spectral Assignment Using Doubleresonance Heteronuclear Methods

Assignment of larger ( 10 kDa) proteins is not well suited to homonuclear methods. The number of resonances increases monotonically with the number of residues, and even correlations observed in two-dimensional NMR spectra frequently overlap, precluding assignment. The overlap problem is exacerbated for proteins with a high degree of a-helical content, in which the dispersion of the Ha proton resonances is generally low. The widths of the proton signals increase with the size of the protein, due to the shortening of T2 relaxation times, as the rotational correlation time (tc) increases, leading to Incorporation of NMR-active stable isotopes allows the use of large heteronuclear couplings to transfer magnetization (see Fig. 17.5.3), leading to experiments with high sensitivity. Generally, NMR correlation experiments that rely on a coupling of J Hz require a delay of (2J)-1 sec to fully transfer magnetization. Small couplings (i.e., nJHH) result in large (2J)-1 times, during which...

Carboxylic ester hydrolases EC 311 and amidases EC 351354

The prominent member of the B-esterases is the acetyl choline esterase responsible for the inactivation of the neurotransmitter acetyl choline. Organophosphates are mechanism-based inhibitors of B-esterases. Their toxic effects are produced by an accumulation of acetyl choline and therefore by an exaggerated cholinergic activity. The inhibitory effect of the organophosphates is due to the fact that the enzyme phosphoserine ester formed between B-esterases and organophosphates hydrolyzes very slowly, if at all, and thus there is virtually no regeneration of the enzyme. The inhibition of another B-esterase, the neuropathy target esterase (NTE) localized in the central nervous system, leads to neurotoxicity called organophosphorus-induced delayed polyneuropathy (OPIDP). The neurotoxicity observed in some gulf war veterans is suspected to have been caused by a combination of the acetylcholine esterase inhibitor pyridostigmine (used as an antidote against anticholinergic chemical weapons)...

Measurement of the Cellto Cell Transfer of Cytosolic Molecules by FRAP

The FRAP method has been adapted to measure the cell-to-cell exchange of a fluorescent diffusion tracer and to obtain quantitative information on the permeability of gap junctions for small molecules (gap-FRAP 6 ). Ideally, the permeability coefficient (P) of the gap junctional membrane should be obtained. As in other biological membranes, P, which measures the ease of passage of a solute (s) driven by its kinetic energy, is equal to the diffusion constant (Ds) of the substance inside the membrane, divided by the thickness (x) of the membrane in a gap junction, x is the length of the unit channel. The permeability coefficient is the flux of substance that crosses the unit area of membrane in unit time when the concentration gradient at the edges of the membrane is equal to unity. To measure a net flux of diffusible substance across a membrane separating two compartments, a concentration gradient must exist between both sides, either in natural conditions or after establishment by the...

Other Protein Nmr Techniques And Future Directions

As the molecular weight of a protein increases, it becomes more and more challenging to generate data amenable to interpretation and assignment. The most obvious effect of increasing molecular weight is the increased number of resonances in discrete spectral regions, yielding chemical shift degeneracy. In addition, the correlation time (tc) increases with molecular weight, resulting in more efficient T2 relaxation and hence broader lines. As a result, correlation experiments that rely on small J couplings become extremely inefficient. The dipolar interaction between protons also contributes significantly to increased rates of relaxation and to spin diffusion in nOe experiments. The dipolar interaction between protons and 13C and 15N also becomes more efficient, resulting in lower sensitivity for double- and triple-resonance experiments.

Adult Smoking Cessation

Proaches to smoking cessation (Fagerstrom, 1988 Hymowitz, 1999). Multi-component behavioral programs, whether in group, individual, or self-help formats, typically include a number of strategies (self-monitoring, stimulus-control procedures, behavioral contracting, alternative behaviors, aversive conditioning, relaxation training, diet and exercise, self-management skill training for relapse prevention, etc.) to motivate smokers, to help them gain control over smoking, and to eliminate smoking systematically from their behavioral repertoire. Once smokers stop smoking, many of the very same behavioral skills that helped them quit smoking are used to help them prevent relapse. Schwartz (1987) reported that 1-year quit rates for multicomponent behavioral group quit-smoking programs average 40 . Initial end-of-treatment quit rates may be considerably higher. Hall, Tunstall, Rugg, Jones, and Benowitz (1985) studied the effects nicotine gum and intensive behavioral treatment. They assigned...

Optical characteristics of the eye

Produced by the ciliary muscles attaching to the peripheral suspensory ligament. Ciliary muscle relaxation causes flattening of the lens, increasing its focal length. Focussing on a closer object is achieved by ciliary muscle contraction. The closest point on which the eye can focus is the near point. The amplitude of accommodation decreases with age (presbyopia). Overall, the refractive power of the eye depends on

Structure Calculation

New directions when using sparse data are explored in which NOEs between the side chains that are difficult to measure and are not required any more. Along these lines, the determination of a structure without any NOEs has been demonstrated on several examples,70 either relying only on several sets of dipolar couplings for the backbone or by also taking paramagnetic restraints such as relaxation and pseudocontact shifts into account.71 The residual structure of alpha-synuclein, a partially unfolded protein, is demonstrated that has been derived mainly from dipolar couplings as well as paramagnetic relaxation restraints ( ). The monomeric form adopts a

Offlattice Minimalist Models

Recently a different modification of the classic 46-mer P-barrel model was suggested. In this case a single side group, represented by a bead that may be hydrophilic or hydrophobic, was added to the model 44 . Molecular dynamics and quenching simulations showed that the nature and the location of the single side group bead influences both the structure at the global minimum of internal energy and the relaxation process by which the system finds its minima. The most drastic effects occur with a hydrophobic side group in the middle of a sequence of hydrophobic residues.

Sub Correlation Time Dynamics

The most common approach is the measurement of relaxation parameters of the backbone nitrogens in proteins that report on motion on timescales faster than the correlation time. The nitrogen has a dipolar coupling to the amide proton and it has a rather well-defined CSA that is moderately asymmetric and almost parallel to the direction of the NH bond. Three parameters can be measured rather easily T1, the longitudinal relaxation time of the nitrogens, and 72, the transverse relaxation time of the nitrogens as well as the steady state NOE of the 15N upon irradiation into the amide proton.108

Is to ms Dynamics on the Scale

Motion slower than the correlation time is not picked up by 71 and heteronuclear NOE and requires different ways of measurement. One approach is the so-called relaxation dispersion, which measures the modulation of chemical shifts due to interconversion of conformations. Provided conformations have different chemical shifts, then an exchange process will average the two chemical shifts involved. For an exchange process that is fast on the chemical shift frequency scale kcAu, the linewidth is given by112 The linewidth is measured in the time domain by variation of a delay during which the transverse coherence decays. This also allows one to apply a transverse magnetic field of adjustable field strength, which then reports also on the timescale of the chemical shift exchange. The result of these measurements is then a rate of interconversion and in addition the product of the populations of the involved species and the difference in chemical shifts. Relaxation dispersion is broadly...

Ns to is Dynamics on the Scale

The gap between the timescale accessible by relaxation measurements and by relaxation dispersion is between the correlation time and approximately 100 ms. The rates here are too fast to access by relaxation dispersion unless nuclei whose chemical shifts are strongly dependent on conformation are used, such as 19F and they are slower than the correlation time. Here, the measurement of dipolar couplings can be undertaken. Dipolar couplings are averaged over all timescales until exchange processes between different conformations become so slow that individual chemical shifts can be observed. If a vector between two dipolar coupled spins moves the average dipolar coupling is smaller. While this can be measured directly in solid-state spectra, e.g., from the Pake pattern in solid-state spectra, in liquid-state spectra it requires the measurement of dipolar couplings in five linearly independent alignment media. From such measurements, however, the size of the dipolar coupling can be...

Chemical Strengthening

Chemical strengthening is another method used to increase the strength of glasses and ceramics. The principle of chemical strengthening relies on the exchange of small alkali ions for larger ions below the strain point of the ceramic. Because stress relaxation is not possible in this temperature range, the exchange leads to the creation of a compressive layer at the surface of the ceramic. Finally, any applied load must first overcome this built-in compression

Lower Urinary Tract Symptoms and Sexual Dysfunction

Sexual dysfunction is poorly understood, although a number of common components have been identified such as upregulation of -adrenoceptor activity, alteration in a1-adrenoceptor subtypes, decreased NO bioactivity, and sex hormone imbalance. -Adrenoceptors are involved in the maintenance of smooth muscle contraction and relaxation in penile tissue. It has been suggested that any impairment of these receptors and their regulators such as the Rho Rho-kinase pathway will contribute to smooth muscle dysfunction, which is evident in both LUTS and erectile dysfunction. Endothelium dysfunction as a result of ROS-induced NO breakdown can also contribute to LUTS and erectile dysfunction. Testosterone alterations are well established as a cause of BPH and LUTS, and it is likely that any androgen imbalances may also lead to erectile dysfunction. For more information on sexual dysfunction, see Chapter 6.23.

Calculation of Differences in the Energy Change of the Protein

The first step in the analysis is to examine the energetics of experimental structures of multiple homologous proteins, preferably with measured redox potentials. An assumption that is generally made is that most of any redox potential differences between homologous proteins are not due to entropic effects, so that AG2 - AGi AAG AAE, where the subscripts refer to proteins 1 and 2. Furthermore, it is assumed that most of the differences lie in the electrostatic energy 18 . In most cases experimental structures are determined only for one oxidation state of the protein. An approximation to overcome this limitation is to assume that the structural relaxation of the homologous proteins is similar so that AAEr 0, and the electrostatics of only a single state can be examined. Thus, using Eq. (7),

Endotheliumderived relaxing factor

In 1980, Furchgott discovered that the endothelium is responsible for the vasodilator action of acetylcholine (10). This finding has fostered a great number of investigations on the role of the endothelium on the initiation and development of vascular disease and its subsequent clinical sequelae. Further research indicated that acetylcholine released a soluble factor from the endothelium termed EDRF and that this substance was released by other agents including bradykinin, substance P, serotonin, and adenosine triphosphate (ATP), and shear stress (11). Ignarro used spectral analysis of hemoglobin to prove that EDRF was identical to NO (12). Shortly thereafter, Palmer and colleagues concluded that NO was derived from the terminal guanidino nitrogen of the amino acid L-arginine. The production of NO is catalyzed by the family of enzymes known as NO synthase (NOS) (13). Three isoforms of NOS have been identified endothelial NOS (eNOS), neuronal NOS (nNOS), and cytokine-inducible NOS...

Energy States of Molecules Light Absorption and the Excited State

Absorption of a photon imparts an energy, hv, to the electron distribution and imparts an oscillation, at frequency v, to an electronic dipole of the molecule. This transition moment, or transition dipole, will be shown to be a key element of FRET. For now, consider the change in energy state of a molecule that has interacted with a photon. Figure 18.10.2 shows a simplified and modified version of Figure 18.10.1. This so-called Jablonski diagram describes the increase in electronic energy after absorbing a photon and the relaxation from higher energy states back to the ground state. Begin at S0, the lowest

Mechanisms of Renal Dysfunction

Calmodulin displaces caveolin-1, activating eNOS and leading to production of NO, which diffuses to vascular smooth muscle and causes relaxation by activating guanylate cyclase, to increase cyclic guanosine monophosphate (cGMP) levels which in turn produce a vasodilatory response.25

Callitrichine and ateline ecology

The absence of female kin bonding emphasised in phylogenetic analyses of callitrichines and atelines is only partially consistent with ecological predictions. Vulnerability to predation may account for the cohesive groups of the small-bodied callitrichines (Caine, 1993), while the relaxation of predation pressures may account for the tendencies of the large-bodied atelines to adjust their grouping patterns in response to the size of food patches. The fruit, invertebrate prey, and plant exudates eaten by calli-thrines include defensible resources that could lead to female kin bonding unless, as van Schaik (1989, p. 212) has noted, 'female dispersal is enforced by some other factor'. The social and hormonal mechanisms that can inhibit reproduction in subordinate callitrichines may exemplify one such 'other factor'. Both the individualistic (non-kin) hierarchies among some female Saguinus and the nepotistic (kin) hierarchies among female Callithrix (Garber, 1994) are consistent with the...

Management of Renal Dysfunction

Aside from the classic treatment of hypertension, an emerging approach to renal dysfunction is the treatment of the components that trigger endothelial dysfunction, e.g., NO bioavailability and oxidative stress. For example, oral treatment with L-arginine, the precursor of NO, reduces blood pressure and improves endothelial dysfunction in hypertensive patients.60 Statins and lipid-lowering drugs improve endothelial dysfunction in hypertensive animal models by enhancing NO levels.61 Antioxidants also can improve endothelial dysfunction in hypertensive animal models. For example, the SOD mimetic tempol decreases hypertension and oxidation stress and improves endothelium-dependent relaxation and kidney damage in hypertensive animal models such as AT-II-infused mice and Dahl salt-sensitive rats.62

Endothelium Dependent Vasodilation in Animal Models

Similarly, in an animal model of type 2 diabetes, the Zucker rat, which is characterized by hyperglycemia because of insulin resistance, abnormal endothelium-dependent va-sodilation is also seen (46). The early vascular dysfunction that occurs in type 1 diabetic animal models can be prevented by insulin therapy (50,51). The abnormal endothelial cell function that develops appears to be as a result of hyperglycemia rather than any other metabolic disturbance. This has been demonstrated by in vitro incubation experiments in which isolated arteries exposed to elevated glucose concentrations have similar decreases in endothelium-dependent vasodilation (52,53). This effect does not seem to be as a result of the hyperosmolarity because similar concentrations of mannitol have no effect on endothelium-dependent relaxation (52). The decreased endothelium-dependent vasodi-lation that occurs may be as a result of decreased synthesis or release of NO, decreased Early in the course of experimental...

New MRI Techniques Uspio Mri

Previous reports have shown that the information about lymph nodes on MR images can be improved by pharmaceutical manipulation of tissue proton relaxation times. Ultra small Super Paramagnetic Iron Oxide Particles (USPIO) with a long plasma circulation time have been shown to be suitable as a MR contrast agent for intravenous MR lymphangiography (Fig. 21) 87-90 . In a study performed at UMC in Nijmegen and Mass General

Human Studies of Endothelium Dependent Vasodilation

Human studies evaluating the effects of DM on endothelium-dependent vasodilation have yielded some conflicting results, although they generally corroborate those found in animal studies. Saenz de Tejada et al. (60) studied penile tissue excised from men with erectile dysfunction and found that endothelium-dependent relaxation is reduced in the corpus cavernosa of impotent men with diabetes relative to those who are nondiabetic. However, in vivo studies involving human subjects with insulin-dependent diabetes have demonstrated both blunted and normal vasodilatory responses to acetylcholine, methacholine, or carbachol (the latter two being acetylcholine analogs) in forearm resistance vessels in patients with DM (61-63). To evaluate in vivo endothelial function in these vessels, we and others have employed the venous occlusive plethysmography technique. Type 1 diabetic (61) individuals were shown to have impaired endothelium-dependent responses to methacholine in the forearm resistance...

Aids Palliative Care And Death And Dying

Different methods of comfort care such as pastoral care, hypnosis, music, relaxation, meditation, writing, and art can be incorporated with much success, and these methods need to be integrated and offered to persons during the entire course of their illness on a routine basis (Cohen, 1999). Depression, anxiety, pain, and other mental health disorders need to be addressed with both psychotherapy and pharmaco-therapy using multiple models, including crisis, individual, group, and family therapy, over the entire spectrum of illness. Integration of spiritual care has been shown to provide comfort and solace to persons suffering with cancer (Saunders, 1988 Jacox et al., 1994). Attempts to provide these interventions across the spectrum of HIV illness will improve the seamless attention given to the associated suffering and distress.

Gender Ethnicracial And Life Span Considerations

Assess the effects of a chronic illness on the patient and family if the patient does not get enough rest or relaxation, suggest lifestyle changes that might decrease stress. Heavy smokers may acquire certain hemoglobin abnormalities that can lead to secondary polycythemia.

Possible mechanisms of impaired endotheliumdependent vasodilation

Although the data are conflicting, overwhelming evidence presently suggests that DM is associated with an impairment of endothelial vasodilation. The mechanism(s) for this impairment is even less well understood. The most likely initial insult is hyperglycemia. Tesfamarian and colleagues took normal rabbit aortic rings and exposed them to high concentrations of glucose (up to 800 mg dL for 3 hours), resulting in a decrease in endothelium-dependent relaxation, in response to acetylcholine and ADP (52,53). This effect appears to be both concentration and time dependent. As stated earlier, this effect does not appear to be a result of the hyperosmolar effects of glucose because mannitol did not cause any such endothelium-dependent vasodilation (53). Bohlen and Lash (73) demonstrated that hyperglycemia at 300 and 500 mg dL suppressed the vasodilatory response to acetylcholine but not to nitroprusside. Similarly, Williams and colleagues (68) found that acute hyperglycemia attenuated...

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