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Physiological Systems (physiological + system)
Selected AbstractsPrimary orthostatic tremor is an exaggeration of a physiological response to instabilityMOVEMENT DISORDERS, Issue 2 2003Andrew Sharott BSc Abstract Primary orthostatic tremor (POT) is a rare disorder characterised by an intense sense of unsteadiness upon standing and a 16-Hz tremor in which the timing between tremor bursts in different muscles (unilateral and bilateral) remains constant. Hitherto, similar EMG activity has not been described in healthy subjects and it has been postulated that the oscillations seen in POT are primarily pathological. In this study, EMG was recorded from tibialis anterior in healthy subjects who were made unsteady through vestibular galvanic stimulation or leaning backwards. Under these conditions, a peak at approximately 16 Hz was seen in the coherence between the left and right tibialis anterior. This bilateral coherence was absent when the subjects activated the same muscles when not unsteady. These data indicate the existence of a physiological system involved in organising postural responses under circumstances of imbalance and characterised by a highly synchronised output at approximately 16 Hz. In addition, the results suggest that the core abnormality in POT may be an exaggerated sense of unsteadiness when standing still, which then elicits activity from a 16-Hz oscillator normally engaged in postural responses. © 2002 Movement Disorder Society [source] The intracrine hypothesis and intracellular peptide hormone actionBIOESSAYS, Issue 4 2003Richard N. Re There is evidence that many peptide growth factors and hormones act in the intracellular space after either internalization or retention in their cells of synthesis. These factors, commonly called intracrines, are structurally diverse while sharing some common functional features. Reports of intracellular peptide hormone binding and action are reviewed here. Also, this laboratory has made proposals regarding the origin and actions of intracrines and these areas are further explored. Intracrine interactions and the relationship of intracrines to transcription factors are discussed. The intracellular/intracrine renin,angiotensin system (iRAS) is reviewed to illustrate the intracrine analogue of a well-established physiological system. The role of intracrine action in metazoan development is also considered. BioEssays 25:401,409, 2003. © 2003 Wiley Periodicals, Inc. [source] Effects of policosanol treatment on the susceptibility of low density lipoprotein (LDL) isolated from healthy volunteers to oxidative modification in vitroBRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 3 2000Roberto Menéndez Aims The aim of this study was to investigate the effect of policosanol on the susceptibility of LDL-C to in vitro lipid peroxidation in human healthy volunteers. Methods The effect of policosanol (5 and 10 mg day,1) on LDL-C oxidation was studied in a double-blind, randomized, placebo-controlled trial conducted in 69 subjects. LDL-C samples isolated at baseline and after 8 weeks were subjected to in vitro tests of LDL-C oxidation. We tested the susceptibility of LDL-C to lipid peroxidation in a cell-free system by the addition of copper ions as well as in a more physiological system, macrophage-mediated oxidation. Results At baseline all groups were well matched regarding all variables. After 8 weeks of therapy policosanol administered at 5 and 10 mg, significantly and in a dose-dependent manner increased the lag phase of conjugated diene generation (mean ± s.d.) from 83.79 ± 29.16 min to 94.90 ± 25.50 min (5 mg day,1) and from 82.74 ± 17.16 min to 129.89 ± 35.71 min (10 mg day,1), while in the placebo group LDL-C oxidation did not change significantly. Policosanol (10 mg day,1), but not placebo, significantly decreased the rate of conjugated diene generation. Comparison with placebo after therapy also showed significant differences. Macrophage mediated-oxidation was also inhibited by policosanol as evident by measuring thiobarbituric acid reactive substances (TBARS). Policosanol (10 mg day,1) significantly lowered malondialdehyde (MDA) generation from 8.50 ± 0.91 to 5.76 ± 1.01 nmol mg,1 protein. Comparison with placebo after 5 and 10 mg day,1 showed significant differences. Policosanol significantly lowered total cholesterol by 10.5% (5 mg day,1) and 12.4% (10 mg day,1) and LDL-C by 16.7% and 20.2%, respectively. Also, policosanol (10 mg day,1) increased HDL-C by 15.2%. Five subjects withdrew from the study, none because of adverse experiences. No clinical or blood biochemical drug-related disturbances were found. Conclusions The present study demonstrated that policosanol administered within its therapeutic dosage for lowering cholesterol (5 and 10 mg day,1), decreased the susceptibility of LDL-C to lipid peroxidation in vitro. [source] Transgenic mice for studies of the renin,angiotensin system in hypertensionACTA PHYSIOLOGICA, Issue 4 2004J. L. Lavoie Abstract Hypertension is a polygenic and multi-factorial disorder that is extremely prevalent in western societies, and thus has received a great deal of attention by the research community. The renin,angiotensin system has a strong impact on the control of blood pressure both in the short- and long-term, making it one of the most extensively studied physiological systems. Nevertheless, despite decades of research, the specific mechanisms implicated in its action on blood pressure and electrolyte balance, as well as its integration with other cardiovascular pathways remains incomplete. The production of transgenic models either over-expressing or knocking-out specific components of the renin,angiotensin system has given us a better understanding of its role in the pathogenesis of hypertension. Moreover, our attention has recently been refocused on local tissue renin,angiotensin systems and their physiological effect on blood pressure and end-organ damage. Herein, we will review studies using genetic manipulation of animals to determine the role of the endocrine and tissue renin,angiotensin system in hypertension. We will also discuss some untraditional approaches to target the renin,angiotensin system in the kidney. [source] Advanced glycation endproducts: what is their relevance to diabetic complications?DIABETES OBESITY & METABOLISM, Issue 3 2007N. Ahmed Glycation is a major cause of spontaneous damage to proteins in physiological systems. This is exacerbated in diabetes as a consequence of the increase in glucose and other saccharides derivatives in plasma and at the sites of vascular complications. Protein damage by the formation of early glycation adducts is limited to lysine side chain and N-terminal amino groups whereas later stage adducts, advanced glycation endproducts (AGEs), modify these and also arginine and cysteine residues. Metabolic dysfunction in vascular cells leads to the increased formation of methylglyoxal which adds disproportionately to the glycation damage in hyperglycaemia. AGE-modified proteins undergo cellular proteolysis leading to the formation and urinary excretion of glycation free adducts. AGEs may potentiate the development of diabetic complications by activation of cell responses by AGE-modified proteins interacting with specific cell surface receptors, activation of cell responses by AGE free adducts, impairment of protein,protein and enzyme,substrate interactions by AGE residue formation, and increasing resistance to proteolysis of extracellular matrix proteins. The formation of AGEs is suppressed by intensive glycaemic control, and may in future be suppressed by thiamine and pyridoxamine supplementation, and several other pharmacological agents. Increasing expression of enzymes of the enzymatic defence against glycation provides a novel and potentially effective future therapeutic strategy to suppress protein glycation. [source] Empirical support for a multi-dimensional model of sensations experienced by youth during their initial smoking episodesADDICTION, Issue 10 2010Chris G. Richardson ABSTRACT Aims To examine the dimensionality of sensations experienced during initial tobacco smoking. Design Cross-sectional survey. Setting Thirteen secondary schools located in British Columbia, Canada. Participants Data from 1187 adolescents who responded ,yes' to the question: ,Have you ever tried cigarette smoking, even one or two puffs?'. Measurements Participants answered questions about their demographic characteristics, tobacco smoking history and sensations experienced during their initial smoking episodes. Findings The sensations appear to represent the following three separate but modestly correlated dimensions: a pleasant dimension defined by feeling good and relaxed; an unpleasant dimension defined by coughing, feeling sick and nervous; and a ,buzz' dimension defined by feeling high and dizzy. The three factors made statistically significant contributions to the prediction of transition to regular smoking (defined as having smoked at least 100 cigarettes in one's life-time) after adjusting for age, sex and age at first puff. Conclusions The results suggest that three relatively distinct physiological systems appear to explain the relationship between initial smoking sensations and probability of becoming a regular smoker. Researchers examining sensations experienced during initial tobacco smoking episodes should consider using a three-dimensional profile of symptoms composed of pleasant, unpleasant and buzz dimensions. [source] Hormones as epigenetic signals in developmental programmingEXPERIMENTAL PHYSIOLOGY, Issue 6 2009Abigail L. Fowden In mammals, including man, epidemiological and experimental studies have shown that a range of environmental factors acting during critical periods of early development can alter adult phenotype. Hormones have an important role in these epigenetic modifications and can signal the type, severity and duration of the environmental cue to the developing feto-placental tissues. They affect development of these tissues both directly and indirectly by changes in placental phenotype. They act to alter gene expression, hence the protein abundance in a wide range of different tissues, which has functional consequences for many physiological systems both before and after birth. By producing an epigenome specific to the prevailing condition in utero, hormones act as epigenetic signals in developmental programming, with important implications for adult health and disease. This review examines the role of hormones as epigenetic signals by considering their responses to environmental cues, their effects on phenotypical development and the molecular mechanisms by which they programme feto-placental development, with particular emphasis on the glucocorticoids. [source] Computational physiology and the physiome projectEXPERIMENTAL PHYSIOLOGY, Issue 1 2004Edmund J. Crampin Bioengineering analyses of physiological systems use the computational solution of physical conservation laws on anatomically detailed geometric models to understand the physiological function of intact organs in terms of the properties and behaviour of the cells and tissues within the organ. By linking behaviour in a quantitative, mathematically defined sense across multiple scales of biological organization , from proteins to cells, tissues, organs and organ systems , these methods have the potential to link patient-specific knowledge at the two ends of these spatial scales. A genetic profile linked to cardiac ion channel mutations, for example, can be interpreted in relation to body surface ECG measurements via a mathematical model of the heart and torso, which includes the spatial distribution of cardiac ion channels throughout the myocardium and the individual kinetics for each of the approximately 50 types of ion channel, exchanger or pump known to be present in the heart. Similarly, linking molecular defects such as mutations of chloride ion channels in lung epithelial cells to the integrated function of the intact lung requires models that include the detailed anatomy of the lungs, the physics of air flow, blood flow and gas exchange, together with the large deformation mechanics of breathing. Organizing this large body of knowledge into a coherent framework for modelling requires the development of ontologies, markup languages for encoding models, and web-accessible distributed databases. In this article we review the state of the field at all the relevant levels, and the tools that are being developed to tackle such complexity. Integrative physiology is central to the interpretation of genomic and proteomic data, and is becoming a highly quantitative, computer-intensive discipline. [source] The physiological basis of human sexual arousal: neuroendocrine sexual asymmetryINTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2005ION G. MOTOFEI Summary Normal sexual arousal and response suppose an integrated process involving both physiological and psychological processes. However, the current understanding of sexual arousal does not provide a coherent model that accounts for the integration of multiple physiological systems that subsequently generate a coordinated sexual response at both the spinal peripheral and cerebral central levels. Herein we suggest a model that involves both sympathetic and parasympathetic activation during sexual arousal via the two classes of gonadal hormones, androgens and oestrogens. We discuss the manner in which gonadal hormones may activate such a system, transforming pre-pubertal (non-erotic) genital stimulation to post-pubertal erogenization of stimulation and subsequent sexual arousal. Finally, we indicate that the different balance of androgens and oestrogens in men and women may generate asymmetric effects on each of the components of the autonomic nervous system, thereby explaining some of the differences in patterns of sexual arousal and the responses cycle across the sexes. [source] Physiological effects of emotional odorsINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2004T. S. Lorig Advances in neuromaging have provided new and exciting knowledge concerning how odors come to activate emotional systems in the brain. Often neglected are the concomitant changes that follow this activation throughout the body. Odor-induced emotional changes in peripheral physiological systems will be critically discussed including changes in respiration, muscle tone, skin conductance and heart rate. Multidimensional patterning of these responses may prove especially valuable in identifying subtle emotional response. Research to date, however, contains few examples of successful response patterning related to odors. [source] Allostatic Load and Frailty in Older AdultsJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 9 2009Tara L. Gruenewald PhD OBJECTIVES: To examine the association between allostatic load (AL), an index of multisystem physiological dysregulation, and frailty development over a 3-year follow-up in a sample of older adults. DESIGN: Longitudinal cohort study. SETTING: Community. PARTICIPANTS: High-functioning men and women aged 70 to 79 at study entry. MEASUREMENTS: Multisystem physiological dysregulation, or AL, was assessed according to 13 biomarkers of cardiovascular, endocrine, immune, and metabolic function. An AL score was computed as the total number of biomarkers for which participant values fell into high-risk biomarker quartiles. Frailty status (not frail, intermediate frail, frail) was determined according to the total number of five indicators of frailty: weight loss, exhaustion, weak grip, slow gait, and low physical activity. The association between level of AL at baseline and frailty status 3 years later was examined using ordinal logistic regression in 803 participants not frail at baseline. RESULTS: In a multivariable model adjusting for sociodemographic, health, and behavioral characteristics, each 1-unit increase in AL at baseline was associated with a 10% greater likelihood of frailty at the 3-year follow-up (cumulative adjusted odds ratio=1.10, 95% confidence interval=1.03,1.19). CONCLUSION: These findings support the hypothesis that dysregulation across multiple physiological systems is associated with greater risk of frailty. Greater levels of multisystem physiological dysregulation may serve as a warning sign of frailty development in later life. [source] Cardiovascular Actions of Orexin-A in the Rat Subfornical OrganJOURNAL OF NEUROENDOCRINOLOGY, Issue 1 2007P. M. Smith Orexin-A is a neuropeptide, primarily produced in the lateral hypothalamic/perifornical hypothalamus. Orexin receptors and immunoreactive neuronal fibres are widely distributed throughout the brain, suggesting integrative neurotransmitter roles in a variety of physiological systems. Intracerebroventricular injections of orexin-A increase blood pressure and stimulate drinking, and the subfornical organ (SFO), a circumventricular structure implicated in autonomic control, is a potential site at which orexin may act to exert these effects. We have therefore used microinjection techniques to examine the effects of orexin-A administered directly into the SFO on blood pressure and heart rate in urethane anaesthetised male Sprague-Dawley rats. Orexin-A microinjection (50 fmol) into the SFO caused site-specific decreases in blood pressure (SFO: mean area under curve (AUC) = ,681.7 ± 46.8 mmHg*s, n = 22 versus non-SFO: 63.68 ± 54.69 mmHg*s, n = 15, P < 0.001), and heart rate (SFO: mean AUC = ,26.7 ± 2.8 beats, n = 22, versus non-SFO: mean AUC = 1.62 ± 2.1 beats, n = 15, P < 0.001). Vagotomy did not alter the hypotensive or bradycardic responses elicited by orexin-A microinjection. Prior ,-adrenoceptor blockade with phenoxybenzamine (1 mg/kg, i.v.) masked the orexin-A induced blood pressure (mean AUC = ,122.6 ± 17.6 mmHg*s, n = 4, P < 0.01 paired t-test) and heart rate (mean AUC = ,6.7 ± 1.7 beats, n = 4, P < 0.05, paired test) response. The orexin-A induced heart rate response was attenuated when ,-adrenoceptors were blocked with propranolol (1 mg/kg, i.v.; mean AUC = 0.6 ± 2.8 beats, n = 5, P < 0.01 paired t-test). These studies demonstrate that microinjection of orexin-A into the SFO causes site specific decreases in blood pressure and heart rate which is mediated by a reduction in sympathetic tone. [source] The host,parasite neuroimmunoendocrine network in schistosomiasis: consequences to the host and the parasitePARASITE IMMUNOLOGY, Issue 12 2007J. MORALES-MONTOR SUMMARY The physiological interactions during the course of any immune response are complex. Infection induces antigen-specific recognition by the immune system, which is consequently charged with the responsibility of marshalling the appropriate effector responses necessary to destroy the pathogen, or at the very least inhibit its progression. Obviously, the immune system should accomplish this while minimizing collateral damage to the host or it risks, winning a Pyrrhic victory. As our understanding of the neuroendocrine system grows, it has become increasingly clear that this complex network of neurotransmitters, hormones and cytokines plays an important role in mediating immunity. Schistosomes present an especially complex relationship between pathogen and these physiological systems, with hormonally dependent host factors such as sex and age correlated with parasite success. In this report, we review the current literature on sex and age associations between infection and progression of disease. We then follow with a discussion on interactions between the host neuroendocrine and immune systems. We also speculate on strategies to apply this knowledge to novel treatment strategies. Results argue for a complex network comprising the immune, endocrinological and nervous systems of both host and schistosome in the regulation of the plural outcomes of infection. [source] Social stress, visceral obesity, and coronary artery atherosclerosis: product of a primate adaptationAMERICAN JOURNAL OF PRIMATOLOGY, Issue 9 2009Carol A. Shively Abstract Abdominal obesity is prevalent and often accompanied by an array of metabolic perturbations including elevated blood pressure, dyslipidemia, impaired glucose tolerance or insulin resistance, a prothrombotic state, and a proinflammatory state, together referred to as the metabolic syndrome. The metabolic syndrome greatly increases coronary heart disease (CHD) risk. Social stress also increases CHD although the mechanisms through which this occurs are not completely understood. Chronic stress may result in sustained glucocorticoid production, which is thought to promote visceral obesity. Thus, one hypothesis is that social stress may cause visceral fat deposition and the metabolic syndrome, which, in turn increases CHD. CHD is caused by coronary artery atherosclerosis (CAA) and its sequelae. Cynomolgus monkeys (Macaca fascicularis) are a well-established models of CAA. Social subordination may be stressful to cynomolgus monkeys and result in hypercortisolemia and exacerbated CAA in females. Herein is reviewed a body of literature which suggests that social stress increases visceral fat deposition in cynomolgus monkeys, that subordinate females are more likely than dominants to have visceral obesity, that females with visceral obesity have behavioral and physiological characteristics consistent with a stressed state, and that females with high ratios of visceral to subcutaneous abdominal fat develop more CAA. While these relationships have been most extensively studied in cynomolgus macaques, obesity-related metabolic disturbances are also observed in other primate species. Taken together, these observations support the view that the current obesity epidemic is the result of a primate adaptation involving the coevolution with encephalization of elaborate physiological systems to protect against starvation and defend stored body fat in order to feed a large and metabolically demanding brain. Social stress may be engaging these same physiological systems, increasing the visceral deposition of fat and its sequelae, which increase CHD risk. Am. J. Primatol. 71:742,751, 2009. © 2009 Wiley-Liss, Inc. [source] Muscarinic cationic current in gastrointestinal smooth muscles: signal transduction and role in contractionAUTONOMIC & AUTACOID PHARMACOLOGY, Issue 3 2006T. Unno Summary 1 The muscarinic receptor plays a key role in the parasympathetic nervous control of various peripheral tissues including gastrointestinal tract. The neurotransmitter acetylcholine, via activating muscarinic receptors that exist in smooth muscle, produces its contraction. 2 There is the opening of cationic channels as an underlying mechanism. The opening of cationic channels results in influxes of Ca2+ via the channels into the cell and also via voltage-dependent Ca2+ channels which secondarily opened in response to the depolarization, providing an amount of Ca2+ for activation of the contractile proteins. 3 Electrophysiological and pharmacological studies have shown that the cationic channels as well as muscarinic receptors exist in many visceral smooth muscle cells. However, the activation mechanisms of the cationic channels are still unclear. 4 In this article, we summarize the current knowledge of the muscarinic receptor-operated cationic channels, focusing on the receptor subtype, G protein and other signalling molecules that are involved in activation of these channels and on the molecular characterisitics of the channel. This will improve strategies aimed at developing new selective pharmacological agents and understanding the activation mechanism and functions of these channels in physiological systems. [source] Rapid and simple method for determination of N, -(carboxymethyl)lysine and N, -(carboxyethyl)lysine in urine using gas chromatography[sol ]mass spectrometryBIOMEDICAL CHROMATOGRAPHY, Issue 9 2005Robert Petrovi Abstract A new procedure was developed to determine in urine the concentrations of N, -(carboxymethyl)lysine (CML) and N, -(carboxyethyl)lysine (CEL), the major products of oxidative modification of glycated proteins, to assess levels of oxidative stress in physiological systems. The urine samples were acetonitrile-deproteinized, then derivatized by ethylchloroformate, and N(O,S)-ethoxycarbonyl ethyl esters of amino acids were analysed by isotope dilution gas chromatography[sol ]mass spectrometry. Recovery averaged 89%. Linearity was excellent (r = 0.998,0.999) in the 0.5,25 µmol[sol ]L range for CML and CEL. The limit of detection of this assay was 0.1 µmol[sol ]L (corresponding to 0.20 pmol of CML or CEL on column). Intra-day and inter-day precisions were likewise excellent, with relative standard deviations <4.63 and <6.15%, respectively. Accuracy of CML and CEL determination (15 µmol[sol ]L) was 2.9 and 5.9% of the estimated theoretical value. The time from obtaining the urine sample to determination of the concentration from the chromatographic peak was 80 min or less. This method is sensitive, reproducible, accurate, relatively cheap and very simple. It can be useful for laboratories involved in the diagnosis and monitoring of age-related chronic diseases. Copyright © 2005 John Wiley & Sons, Ltd. [source] | |||||||||||||