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PubMed2000

[Three-dimensional finite element stress analysis of supporting bone of mandibular posterior fixed bridge. Part III. Comparative analysis with stress of the cortical bone beneath different pontics of fixed bridge].

OBJECTIVE: To analysis stress of the cortical bone beneath different pontics of mandibular posterior fixed bridge by using three-dimentional finite element method. METHODS: According to the measured data, the characters of all components of fixed bridge and the supporting tissues, and the principals of finite element, the three-dimentional finite element model was developed on the basis of an adult mandible. The model consisted of 1363 nodes and 1134 elements after the fixed bridge was placed. Three different pontics were designed. Young's mudulus and Poisson's ratio were obtained from the literature for each type of tissue or materials in the model. The surfaces of pontic next to the mucosa beneath the pontic consisted of nine elements and the contact area were respectively reduced 1/3. It was assumed all materials in the model were homogeneous, isotropic and linearly elastic. One vertical load of 20 kg and one horizontal load of 20 kg were applied respectively on the occlusal surface of the abutments and the pontics of three different fixed bridge. Three-dimentional finite element stress analysis was used to calculate the epsilon max and the epsilon min of the cortical bone beneath pontics of fixed bridge. RESULTS: Under the vertical loading, the cortical bone beneath the pontics appeared compressive stresses, the stress values of the cortical bone beneath the pontics were respectively -0.211(-)-0.119 (epsilon max, kg/mm2), -0.355(-)-0.201 (epsilon min), -0.224(-)-0.125 (epsilon max), -0.375(-)-0.215 (epsilon min), -0.239(-)-0.133 (epsilon max), -0.395(-)-0.228 (epsilon min). Under the horizontal loading, the cortical bone beneath the pontics exhibited tensile stresses and compressive stresses. The stress values of the cortical bone beneath the pontics were respectively -0.004-0.283 (epsilon max, kg/mm2), -0.249(-)-0.009 (epsilon min), -0.0042-0.301 (epsilon max), -0.264(-)-0.0095 (epsilon min), -0.0045-0.322 (epsilon max), -0.281(-)-0.0101 (epsilon min). The stress in the cortical bone beneath the pontics increased when the area of contact was reduced, the stress values changed in 5%-7%, but the rules of stress distribution of three different pontics were similar. CONCLUSION: Stress values in the cortical bone beneath three pontics are small, and the change of stress in the cortical bone beneath the different pontics of mandibular posterior fixed bridge is small too.

Dental Abutments↗
PubMed1988

Polypeptide changes induced by salt stress, water deficit, and osmotic stress in barley roots: a comparison using two-dimensional gel electrophoresis.

Two-dimensional polyacrylamide gel electrophoresis was used to analyze and compare the effects of short term treatments (24 h) of salt stress, water deficit (desiccation), and osmotic stress (polyethylene glycol and mannitol) on protein synthesis in roots of barley seedlings (Hordeum vulgare L. cv. CM 72). These comparisons were made to determine if the polypeptides of Mr 26,000 and 27,000 and pI of 6.3 and 6.5 that were observed previously to increase significantly with salt stress (Plant Physiol. 1987, 83 517-524) also increased with water deficit and osmotic stress. The polypeptide patterns for control- and stress-treated plants were qualitatively similar, but the net synthesis of a number of polypeptides was quantitatively altered by each of the stress treatments. Of the polypeptide changes induced by the stress treatments, many were unique to a specific stress. Other polypeptide changes were common between two or more of the stress treatments. Only one polypeptide change, a decrease, was common to all of the stress treatments. An important finding was that polypeptides that increased significantly in response to salt stress did not increase in response to water deficit or osmotic stress.

Edible Grain↗
PubMed2002

Photosynthetic limitations of a halophyte sea aster (Aster tripolium L) under water stress and NaCl stress.

To understand the mechanisms of salt tolerance in a halophyte, sea aster ( Aster tripolium L.), we studied the changes of water relation and the factors of photosynthetic limitation under water stress and 300 mM NaCl stress. The contents of Na(+) and Cl(-) were highest in NaCl-stressed leaves. Leaf osmotic potentials ( Psi(s)) were decreased by both stress treatments, whereas leaf turgor pressure ( Psi(t)) was maintained under NaCl stress. Decrease in Psi(s) without any loss of Psi(t) accounted for osmotic adjustment using Na(+) and Cl(-) accumulated under NaCl stress. Stress treatments affected photosynthesis, and stomatal limitation was higher under water stress than under NaCl stress. Additionally, maximum CO(2) fixation rate and O(2) evolution rate decreased only under water stress, indicating irreversible damage to photosynthetic systems, mainly by dehydration. Water stress severely affected the water relation and photosynthetic capacity. On the other hand, turgid leaves under NaCl stress have dehydration tolerance due to maintenance of Psi(t) and photosynthetic activity. These results show that sea aster might not suffer from tissue dehydration in highly salinized environments. We conclude that the adaptation of sea aster to salinity may be accomplished by osmotic adjustment using accumulated Na(+) and Cl(-), and that this plant has typical halophyte characteristics, but not drought tolerance.

Adaptation, Physiological↗
PubMed1995

Differential cytoprotection against heat stress or hypoxia following expression of specific stress protein genes in myogenic cells.

Cells respond to sub-lethal hear stress by preferential synthesis and accumulation of several members of functionally and compartmentally distinct families of heat shock (or stress) proteins (such as hsp70, hsp90, hsp60 and hsp27). Some of these have been implicated in the development of thermotolerance and resistance to other environmental stresses. The aim of this investigation was to determine the ability of hsp70, hsp90 or hsp60 to individually protect embryonal rat heart-derived H9c2 myocytes against both (i) heat stress and (ii) substrate-free hypoxia. When H9c2 cells were subjected to a sub-lethal stress (43 degrees C for 30 min) they were shown to have elevated levels of hsp70, hsp90 and hsp60 which was maximal between 14-24 h and was associated with increased survival at 24 h against a subsequent lethal heat stress (47 degrees C for 2 h) (20.4 +/- 2.6% v 7.3 +/- 1.8%; P < 0.002). H9c2 myocytes were transfected with a plasmid containing human hsp70i, hsp90 beta or hsp60 expressed under the control of the constitutively active human beta-actin promoter or with control vector alone (containing no hsp gene). Stable colonies of primary transfectants selected for neomycin resistance showed different degrees of over-expression of hsp70i, hsp90 beta or hsp60 expression as determined by Western blotting using specific monoclonal antisera. Cells constitutively expressing high levels of hsp70i showed significantly higher survival against lethal heat stress compared to cells transfected with vector alone (39.2 +/- 6.5% v 4.5 +/- 1.0%; P < 0.0001) and also against 20 h of substrate-free hypoxia (86.4 +/- 3.0% v 3.5 +/- 0.7%; P < 0.0001). Cells constitutively expressing high levels of hsp90 beta also showed significantly higher survival against heat stress (21.5 +/- 3.0% v 9.8 +/- 3.7%; P < 0.05) but were not resistant to 20 hours of substrate-free hypoxia (0.5 +/- 1.0% v 2.0 +/- 1.7%). Cells transfected with the hsp60 plasmid showed no increased survival against either heat stress or substrate-free hypoxia. These results demonstrate that transfection of H9c2 cells with either hsp70i, hsp90 beta or hsp60 genes confers different patterns of protection against heat stress and substrate-free hypoxia, indicating functional differences between stress proteins in their ability to protect against divergent stresses.

Actins↗
PubMed2004

Stress and stress disorders during and after intensive care.

PURPOSE OF REVIEW: We provide an overview of the multilevel/multidimensional approach to stress and stress disorders, and integrate research findings into the intensive care context. Recent findings are discussed within the context of well studied biopsychological theories of stress and stress disorders. RECENT FINDINGS: The stress response must be viewed as a process. It should be discussed in terms of perception, immediate response and prolonged manifestations. There are correlations with biological principles, in that neurotransmitters can be distinguished on the basis of speed of response, duration of action and range of activity. Nevertheless, discussions on vulnerability to stress and the ability to cope with stressors are important. Findings regarding the influence of chronic stress and dysfunction of the hypothalamo-pituitary axis on stress disorders after intensive care encourage us to consider preoperative interventions that reduce chronic stress and therefore re-establish proper function of the hypothalamo-pituitary axis. SUMMARY: Stress disorders can be viewed as a consequence either of the action of humoral substances or of failure to recover. Studies on the process of psychophysiological recovery in the intensive care unit are urgently needed. Patient factors such as type of illness, age and sex should be considered modifiers of the stress response. In addition, the interaction between molecular mechanisms of the tissue healing process and the psychophysiological stress response require more intensive study.

Journal Article↗
PubMed1999

Fuzzy cluster analysis of positive stress tests: comparison with stress echocardiography and nuclear perfusion imaging in patients with triple vessel and left main coronary disease.

Fuzzy cluster analysis (FCA) was used to classify 166 outpatient positive treadmill stress tests as mildly, moderately, or severely abnormal. The method combines ST-segment change with five other stress test variables, and then computes a similarity measure to determine how closely each patient's stress test resembles a prototypical mildly, moderately, or severely abnormal stress test. All patients had coronary angiography within 1 month of their stress tests. For the 45 patients with triple vessel disease (TVD), FCA classified 34 of these stress tests as severely abnormal (sensitivity = 75%). For the 22 patients with left main disease (LM), FCA classified 19 stress tests as severely abnormal (sensitivity = 86%). For the combined group with high-grade disease (TVD + LM), the sensitivity was 79%. A literature review shows that for stress echocardiography, multiple exercise-induced wall motion abnormalities have a sensitivity in the 70-80% range for patients with high-grade disease. For nuclear stress testing, the high-risk pattern of multiple reversible defects, with or without increased lung uptake, has a sensitivity in the range of 70-80% for patients with high-grade disease. Thus classification of a positive stress test as severely abnormal by FCA has a sensitivity comparable to high-risk patterns on stress echocardiography and nuclear stress testing in patients with TVD or LM.

Adult↗
PubMed1999

Comparison of exercise stress testing with dobutamine stress echocardiography and radionuclide ventriculography for diagnosis of coronary artery disease.

Dobutamine stress echocardiography, Tc-99m radionuclide ventriculography (RNVG), and exercise stress testing were performed prospectively in 63 patients with suspected coronary artery disease to compare the values of exercise testing, dobutamine stress echocardiography and RNVG in the non-invasive diagnosis of coronary artery disease. The sensitivities of dobutamine stress echocardiography and RNVG were found to be higher than that of exercise testing (93-62%, p < 0.001; 83-62%, p < 0.05). The sensitivities of dobutamine stress echocardiography and RNVG were similar (p > 0.05). There were no differences between the sensitivities of the three techniques in multiple vessel disease (p > 0.05). The specificities of dobutamine stress echocardiography and RNVG were higher than that of exercise testing (for both of the tests 86-62%, p < 0.05). The diagnostic accuracy of dobutamine stress echocardiography and RNVG were similar (p > 0.05). The results of dobutamine stress echocardiography RNVG were concordant with each other in 46 patients (76%, kappa = 65%) in sectional analysis. Dobutamine stress echocardiography and RNVG tests were comparable with each other in 85% of the 189 segments (kappa = 64%). The expected 5% decrease at peak doses of dobutamine was not detected in stress echocardiography in 25 patients and in RNVG in 26 of the patients. Dobutamine stress echocardiography and RNVG are superior to exercise testing in the diagnosis of single vessel disease and there is no significant difference between the two techniques. When the ejection fraction is considered in dobutamine stress echocardiography and RNVG, it does not make an additional contribution to the diagnosis of coronary artery disease.

Adult↗
PubMed2005

Stress and active oxygen species--effect of alpha-tocopherol on stress response.

Stress is implicated in the pathogenesis of numerous disorders such as cardiovascular diseases or neurodegeneration. The extensive overlap between diseases attributed to stress and oxidative damage is indicative of their potential relationship. We hereby study the influence of alpha-tocopherol (alpha-toc) on the development of stress biomarkers (morphological and biochemical), on specific biomarkers of radical insult (lipid peroxidation, oxidized proteins, or glutathione content in brain and liver), as well as on drug metabolism. In our experimental protocol two groups of female rats are exposed to stress conditions, i.e. cold plus starvation. Before stress and during its application one group is treated with alpha-toc for 20 d (0.42 mmol/kg per os, once daily). Our results indicate that oxidative damage accompanies the development of stress, while treatment with alpha-toc completely prevents stress-induced radical attack and reduces stress indices like plasma corticosterone, uropepsinogen, and morphological changes. It is found that stress increases the drug metabolic potential of the liver (total P450, CYP2E1, or CYP3A1 activity). Administration of alpha-toc, in combination with stress, further increases erythro mycin N-demethylation (CYP3A1) compared to stress control, while 4-nitrophenol hydroxylation (CYP2E1) is not affected significantly.

Administration, Oral↗
PubMed2005

Severe stress events and use of stress-management behaviors are associated with nutrition-related parameters in men with HIV/AIDS.

OBJECTIVE: To determine whether severe stress events and more frequent use of stress-management behaviors among men with human immunodeficiency virus (HIV) infection are associated with more desirable nutrition-related parameters. DESIGN: Data on sociodemographic variables, severe stress events, stress management, and nutrition-related parameters were obtained from interviews, venipunctures, medical record reviews, bioelectrical impedance analysis, and questionnaires from the baseline wave of a three-wave longitudinal study. SUBJECTS/SETTING: The sample consisted of 226 men with HIV who were attending one of three infectious disease clinics. STATISTICAL ANALYSES PERFORMED: Multivariable linear and logistic regression were used to determine the association of severe stress events and mean stress-management subscore with nutrition-related parameters when controlling for CD4(+) T cells, age, income, and race. RESULTS: Men with more severe stress events were more likely to experience nausea (odds ratio=1.4, P<.01) and change in appearance (odds ratio=1.25, P=.02). Men who more frequently used stress-management behaviors had a lower body mass index (beta=-1.14, P=.02), lower percent body fat (beta=-1.12, P=.05), more frequent use of nutritional-health promoting behaviors (beta=.52, P<.01), and were less likely to experience a change in appearance (odds ratio=0.63, P=.05) and have unintentional weight loss (odds ratio=0.54, P=.05). CONCLUSIONS: Men with more severe stress events are more likely to experience undesirable symptoms that could adversely influence nutritional health. More frequent use of stress-management behaviors may provide a coping mechanism for stress associated with HIV and ultimately improve nutritional health of men with HIV/acquired immunodeficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed2003

Effects of gestational stress and neonatal handling on pain, analgesia, and stress behavior of adult mice.

Stressors presented during the late prenatal and early postnatal periods can have long-term effects on offspring behavior, due to the sensitive periods in the formation of brain circuitry associated with early development. This study investigated the long-term effects of prenatal (restraint during the last week of gestation) and postnatal (daily handling for 14 days postnatal) stress, alone and in combination, on adulthood pain behavior, analgesic responses to stress and morphine, and on behavioral indices of stress reactivity. We found that all of the adult responses measured were altered by perinatal manipulations. Nociceptive thresholds were increased by prenatal or by postnatal stress in males and females; application of both stressors in combination negated these effects. Elevations in morphine analgesia were also observed in animals undergoing either perinatal stressor, but not in those who received both stressors. Behavioral and analgesic responses to stress were consistent with previous observations of reduced stress responsiveness following neonatal handling, with some sex-specific findings. Male and female handled subjects exhibited decreases in stress behavior, and both groups of female handled subjects (regardless of prenatal stress [PS] condition) exhibited decreases in stress-induced analgesia (SIA). Males, on the other hand, exhibited decreases in SIA only if they were prenatally stressed (regardless of handling condition). Thus, prenatal and postnatal stressors have differing effects on the neural circuitry underlying pain, pain inhibition, and stress behavior.

Adaptation, Physiological↗
PubMed1998

Acute stress disorder as a predictor of posttraumatic stress symptoms.

OBJECTIVE: Using the DSM-IV diagnostic criteria for acute stress disorder, the authors examined whether the acute psychological effects of being a bystander to violence involving mass shootings in an office building predicted later posttraumatic stress symptoms. METHOD: The participants in this study were 36 employees working in an office building where a gunman shot 14 persons (eight fatally). The acute stress symptoms were assessed within 8 days of the event, and posttraumatic stress symptoms of 32 employees were assessed 7 to 10 months later. RESULTS: According to the Stanford Acute Stress Reaction Questionnaire, 12 (33%) of the employees met criteria for the diagnosis of acute stress disorder. Acute stress symptoms were found to be an excellent predictor of the subjects' posttraumatic stress symptoms 7-10 months after the traumatic event. CONCLUSIONS: These results suggest not only that being a bystander to violence is highly stressful in the short run, but that acute stress reactions to such an event further predict later posttraumatic stress symptoms.

Acute Disease↗
PubMed2006

8-weeks training program attenuates mitochondrial oxidative stress in the liver of emotionally stressed rats.

In recent years it has been shown that emotional stress induced by immobilization may change the balance between pro-oxidant and antioxidant factors inducing oxidative damage. On the other hand, contradictory views exist concerning the role of physical activity on redox metabolism. Consequently, the present work was designed to assess the influence of an 8-week moderate swimming training program in emotionally stressed rats. Sixty 1-month-old male albino Wistar rats weighing 125-135 g were used in this experimental study. They were divided into three groups, as Control (lot A; n=20), Stressed (lot B; n=20) and Stressed & Exercised (lot C; n=20). Rats were stressed by placing the animals in a 25 x 7 cm plastic bottle 1 h/day, 5 days a week for 8 weeks. Protein carbonyl content values in liver homogenates were significantly increased in stressed animals (0.58+/-0.02 vs 0.86+/-0.03; p=0.018) which clearly indicated that emotional stress was associated with oxidative stress. Ultrastructural alterations, predominantly mitochondrial swelling and the decrease of cristae number observed by electron microscopy represented direct evidence of membrane injury. The most striking feature of our study was that we also found differences between stressed rats and stressed rats that performed our 8 week training program. Consequently our results highlight the potential benefit of a moderate training program to reduce oxidative damage induced by emotional stress since it attenuated protein oxidation and mitochondrial alterations.

Animals↗
PubMed1997

Acute stress enhances while chronic stress suppresses cell-mediated immunity in vivo: a potential role for leukocyte trafficking.

Delayed type hypersensitivity (DTH) reactions are antigen-specific, cell-mediated immune responses which, depending on the antigen involved, mediate beneficial (resistance to viruses, bacteria, fungi, and certain tumors) or harmful (allergic dermatitis, autoimmunity) aspects of immune function. We have shown that acute stress administered immediately before antigenic challenge results in a significant enhancement of a skin DTH response in rats. A stress-induced trafficking or redeployment of leukocytes to the skin may be one of the factors mediating this immunoenhancement. Here we investigate the effects of varying the duration, intensity, and chronicity of stress on the DTH response and on changes in blood leukocyte distribution and glucocorticoid levels. Acute stress administered for 2 h prior to antigenic challenge, significantly enhanced the DTH response. Increasing the duration of stress from 2 h to 5 h produced the same magnitude enhancement in cutaneous DTH. Moreover, increasing the intensity of acute stress produced a significantly larger enhancement of the DTH response which was accompanied by increasing magnitudes of leukocyte redeployment. In contrast, chronic stress suppressed the DTH response when it was administered for 3 weeks before sensitization and either discontinued upon sensitization, or continued an additional week until challenge, or extended for one week after challenge. The stress-induced redeployment of peripheral blood lymphocytes was attenuated with increasing exposure to chronic stress and correlated with attenuated glucocorticoid responsivity. These results suggest that stress-induced alterations in lymphocyte redeployment may play an important role in mediating the bi-directional effects of acute versus chronic stress on cell-mediated immunity in vivo.

Acute Disease↗
PubMed1989

A.E. Bennett award paper. Experimental approaches to human stress research: assessment of neurobiological mechanisms of stress in volunteers and psychiatric patients.

This article presents a series of experiments that involves the development of three novel strategies for human stress research and the utilization of these strategies to examine neurobehavioral processes of stress in healthy volunteers, schizophrenia, and affective illness. The first strategy involved intravenous 2-deoxy-D-glucose (2DG) administration, a glucoprivic stressor. We found that glucoprivic stress results in dissociation of hypothalamus-pituitary-adrenal (HPA), adrenomedullary, and sympathoneural activity. In addition, glucoprivic stress in neuroleptic-treated schizophrenic patients caused heightened dopamine activity, as reflected by increased plasma homovanillic acid (HVA) levels and decreased adaptive responses as assessed by decreased food consumption following 2DG administration. These data suggest that neuroleptics do not prevent stress-related increases in dopamine activity and that schizophrenia may be associated with abnormalities in the stress response. The second strategy assessed effects of uncontrollable and identical amounts of controllable stress in volunteers and depressed patients. In volunteers, it was found that uncontrollable in comparison to controllable stress results in specific behavioral and neuroendocrine alterations. Moreover, uncontrollable stress exposure in depressed patients in comparison to volunteers produced greater alterations in behavioral ratings and plasma cortisol levels and that the uncontrollable stress related increases in helplessness ratings and cortisol levels were significantly correlated. These data suggest that depressed patients may have increased sensitivity to uncontrollable stress and that there may be an important interrelationship between the cognitive deficits of depression and the heightened HPA axis activity observed in these patients. Lastly, we used a naturalistic strategy to examine mechanisms relating childhood parental loss and the development of adult affective illness and found that among subjects with early parental loss histories, those who developed adult psychiatric illness had increased resting plasma levels of cortisol and beta-endorphin (ir) as compared with subjects with early loss and no adult history of psychiatric illness. Moreover, increased HPA activity in adulthood was significantly related to poor childhood adjustment to parental loss. The implications of the results of these studies are discussed.

Adrenocorticotropic Hormone↗
PubMed1983

Differential effects of morphine on noradrenaline release in brain regions of stressed and non-stressed rats.

Effects of morphine on noradrenaline (NA) turnover in the 8 brain regions were investigated in non-stressed and stressed rats. Morphine at 3 mg/kg and 6 mg/kg caused dose-dependent increases in levels of 3-methoxy-4-hydroxyphenylethyleneglycol sulfate (MHPG-SO4), the major metabolite of brain NA, in the hypothalamus, amygdala, thalamus, hippocampus and midbrain and decreases in NA levels in the first 4 of these regions. In contrast to these enhancing effects of morphine on NA release in non-stressed rats, pretreatment with morphine at 6 mg/kg significantly attenuated immobilization-stress-induced increases in MHPG-SO4 levels in the above regions. The morphine effects in both states, non-stressed and stressed, were reversed by naloxone at 0.5 mg/kg and 5 mg/kg in the hypothalamus, amygdala and thalamus. These neurochemical changes are apparently related to the distress-evoked hyperemotionality. Behavioral changes observed during the restraint stress such as struggling, vocalization and defecation were attenuated by morphine at 6 mg/kg and enhanced by naloxone at 5 mg/kg, and this action of morphine was also reversed by naloxone at 5 mg/kg. These results suggest that morphine acts to attenuate stress-induced increases in NA release in the hypothalamus, amygdala and thalamus via opiate receptors, although the drug facilitates NA release in these regions in non-stressed rats. Together with previous findings that naloxone enhances stress-induced increases in NA release selectively in these regions, it is further suggested that endogenous opioids released during stress might act to inhibit NA release in these specific brain areas and that these decreased noradrenergic activities might be closely related to the relief of the distress-evoked hyperemotionality in animals.

Animals↗
PubMed1992

Prenatal stress alters brain catecholaminergic activity and potentiates stress-induced behavior in adult rats.

Previous studies demonstrated that throughout the preweaning period prenatally stressed rats have an overactive hypothalamic-pituitary-adrenal (HPA) system. This increased HPA activity was accompanied by an increase in defensive behavior. This study examined whether these alterations in HPA activity and defensive behavior continued into adulthood. Brain catecholamines in the cerebral cortex and locus coeruleus were also measured in prenatally stressed and control rats. Shock-induced levels of defensive freezing were significantly higher in prenatally stressed rats than in controls. However, plasma ACTH and corticosterone concentrations did not differ between groups either in the basal state or after exposure to foot shock. Concentrations of norepinephrine (NE) in the cerebral cortex and locus coeruleus region were significantly reduced in prenatally stressed rats. In addition, concentrations of NE metabolites were significantly elevated in prenatally stressed rats, suggesting an increased turnover of brain NE. Prenatally stressed rats also had, in the locus coeruleus region, significantly reduced dopamine (DA) levels but elevated concentration of DA metabolites. Results indicate that prenatal stress produces an increased behavioral responsiveness to stress that is evident in early life and continues into adulthood. The early hyperactivity of the HPA system in prenatally stressed rats, however, appears to normalize in adulthood. The increased turnover in brain catecholamines measure in the cerebral cortex and locus coeruleus region of prenatally stressed rats may be associated with the heightened expression of stress-induced behavior.

Adrenocorticotropic Hormone↗
PubMed1995

A comparison of stress leak-point pressure and maximal urethral closure pressure in patients with genuine stress incontinence.

OBJECTIVE: To determine the correlation between the maximal urethral closure pressure and the stress leak-point pressure in patients with genuine stress incontinence, and to define a critical stress leak-point pressure value to detect patients with a low-pressure urethra, as defined by a maximal urethral closure pressure less than 20 cm H2O. METHODS: Fifty-nine patients with genuine stress incontinence were evaluated prospectively with multichannel urodynamics. Maximal urethral closure pressures and stress leak-point pressures were determined and correlated. Several stress leak-point pressure values were evaluated by contingency tables to detect a critical level for detecting a low-pressure urethra. RESULTS: There is a statistically significant relationship (P < .0001) between the stress leak-point pressure and the maximal urethral closure pressure. However, a correlation coefficient of 0.56 demonstrates poor clinical relationship. A stress leak-point pressure less than or equal to 45 cm H2O was found to be 80% sensitive and 90% specific in diagnosing a low-pressure urethra. A stress leak-point pressure less than or equal to 60 cm H2O was 90% sensitive and 64% specific in detecting a low-pressure urethra. CONCLUSIONS: The stress leak-point pressure has poor clinical correlation to the maximal urethral closure pressure. A stress leak-point pressure less than or equal to 45 cm H2O has adequate sensitivity and specificity to diagnose a low-pressure urethra. A value less than or equal to 60 cm H2O would be an appropriate cutoff level to screen for those patients at risk of having a low-pressure urethra in need of further evaluation.

Adult↗
PubMed1987

The effects of chronic intermittent stress on basal and acute stress levels of TSH and GH, and their response to hypothalamic regulatory factors in the rat.

The effect of chronic stress on basal and stress-induced alterations of TSH and GH was studied in adult male rats. Chronically stressed rats were subjected 6 days per week for 4 weeks to several acute stressors including saline injections, noise, ether and forced swimming. Each day, one stressor was chosen randomly. Twenty hr after the last stress session, basal levels of TSH were normal or increased, with no altered pituitary response to TRH. In contrast, the TSH rise induced by acute stress was blunted in chronically stressed rats. Chronic stress resulted in lower basal and acute stress levels of GH. These modifications were probably due to changes in the release of hypothalamic regulatory hormones, because no evidence for altered TSH response to TRH, and GH response either to GHRH or to somatostatin, was found. Some abnormal responses of GH to TRH and of TSH to GHRH were observed in chronically stressed rats. These data indicate that this type of chronic stress induced significant changes in basal and acute stress levels of GH and TSH in the rat.

Animals↗