Mental health and vitality predict spinal pain in healthcare workers.

BACKGROUND: Despite extensive investigation of ergonomic risk factors for spinal pain in healthcare workers, limited knowledge of psychological risk factors exists. AIMS: To assess the prospective association of mental health and vitality with development of spinal pain in healthcare workers. METHODS: A prospective cohort study was carried out involving 1950 healthcare workers from 19 hospitals in Denmark. Assessments were done at baseline and at 1-year follow-up. Mental health and vitality were measured using the Short Form-36 Health Survey, while spinal pain intensity was measured using a 0-10 scale in the low-back, upper-back and neck, respectively. Cumulative logistic regressions adjusted for several confounding factors were applied, reporting risk estimates as odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Using good mental health as reference, moderate (but not poor) mental health at baseline was associated with increased pain intensity in the low-back (OR: 1.41 [95% CI: 1.21-1.77]), upper-back (OR: 1.63 [95% CI: 1.31-2.02]) and neck (OR: 1.31 [95% CI: 1.07-1.61]) at 1-year follow-up. Likewise, using high vitality as reference, both moderate and low vitality at baseline were associated with increased pain intensity in the low-back (OR: 1.54 [95% CI: 1.22-1.94] and OR: 2.34 [95% CI: 1.75-3.12], respectively), upper-back (OR: 1.72 [95% CI: 1.34-2.23] and OR: 2.46 [95% CI: 1.86-3.25], respectively) and neck (OR: 1.66 [95% CI: 1.34-2.06] and OR: 2.06 [95% CI: 1.61-2.63], respectively) at 1-year follow-up. CONCLUSIONS: Compared to healthcare workers with good mental health and high vitality, those with moderate mental health and low/moderate vitality, respectively, were more likely to increase spinal pain intensity at 1-year follow-up. These components should also be considered in the prevention of spinal pain in healthcare workers.

Outcome measures used in trials on gait rehabilitation in multiple sclerosis: A systematic literature review.

BACKGROUND: Multiple Sclerosis (MS) is associated with impaired gait and a growing number of clinical trials have investigated efficacy of various interventions. Choice of outcome measures is crucial in determining efficiency of interventions. However, it remains unclear whether there is consensus on which outcome measures to use in gait intervention studies in MS. OBJECTIVE: We aimed to identify the commonly selected outcome measures in randomized controlled trials (RCTs) on gait rehabilitation interventions in people with MS. Additional aims were to identify which of the domains of the International Classification of Functioning, Disability and Health (ICF) are the most studied and to characterize how outcome measures are combined and adapted to MS severity. METHODS: Pubmed, Cochrane Central, Embase and Scopus databases were searched for RCT studies on gait interventions in people living with MS according to PRISMA guidelines. RESULTS: In 46 RCTs, we identified 69 different outcome measures. The most used outcome measures were 6-minute walking test and the Timed Up and Go test, used in 37% of the analyzed studies. They were followed by gait spatiotemporal parameters (35%) most often used to inform on gait speed, cadence, and step length. Fatigue was measured in 39% of studies. Participation was assessed in 50% of studies, albeit with a wide variety of scales. Only 39% of studies included measures covering all ICF levels, and Participation measures were rarely combined with gait spatiotemporal parameters (only two studies). CONCLUSIONS: Selection of outcome measures remains heterogenous in RCTs on gait rehabilitation interventions in MS. However, there is a growing consensus on the need for quantitative gait spatiotemporal parameter measures combined with clinical assessments of gait, balance, and mobility in RCTs on gait interventions in MS. Future RCTs should incorporate measures of fatigue and measures from Participation domain of ICF to provide comprehensive evaluation of trial efficacy across all levels of functioning.

Objectively and subjectively measured physical activity and its relation to cardiovascular risk factors in older people-Which is most appropriate?

OBJECTIVES: To determine the strength of the association between objectively and subjectively measured physical activity (PA) and cardiovascular risk factors (CVRF) in a sample of older adults to assess which measure of PA is most appropriate for use in this population. STUDY DESIGN AND OUTCOME MEASURES: The study was a cross-sectional analysis of a community-dwelling sample aged 60 years or more (61 women and 34 men). Data collection included anthropometric measurements, blood analytics, and objective and subjective measurements of PA from accelerometers and Yale PA Survey questionnaires, respectively. RESULTS: Although the questionnaire indicated a higher summary index (total units) of PA in men than in women, objective measurements of total PA (mean counts per minute and steps per day) did not differ by sex. However, we obtained different results between women and men when we analyzed the relation between objective and subjective PA parameters and CVRF. In women, parameters that indicate cardiovascular risk, such as body mass index (BMI), waist circumference (WC), glucose, and total cholesterol, negatively correlated with objective PA parameters, while HDLc positively correlated with objective PA parameters and negatively with subjective PA parameters. In men, BMI and WC were negatively correlated with objective PA parameters, while blood cholesterol, LDLc, and triglycerides negatively correlated with subjective PA parameters. CONCLUSIONS: In women, it seems more appropriate to use objective methods to measure PA, while in men, objective and subjective methods seem to be complementary. Both methods of measurement, accelerometers and questionnaires, should be used simultaneously in research studies in older populations to establish precise relationships between PA and cardiovascular risk.

Serum adiponectin is associated with body composition and cognitive and psychological status in older adults living in long-term nursing homes.

Frailty is a geriatric syndrome characterized by decreasing functional reserves and increasing vulnerability to falls, injuries and declining health, leading to dependence upon caregivers. Frailty is associated not only with physical decline, but also with cognitive and psychological impairments in aging people. Higher serum adiponectin concentration has been linked to better performance on frailty measures but also to worse cognitive status. Nonetheless, several studies have proposed adiponectin as a frailty biomarker. To further delineate the relationship between adiponectin serum levels and frailty-related parameters, we studied a population of 112 long-term nursing home residents (aged 84.9 ±â€¯6.7) and analyzed their serum adiponectin levels in conjunction with frailty-related parameters including body composition, physical fitness, cognitive function, psychological parameters and quality of life. Frailty was assessed following the Fried Frailty Criteria, the Clinical Frailty Scale and the Tilburg Frailty Indicator. In women, higher serum adiponectin levels were associated with lower body weight, body mass index, body fat mass, fat mass/height2, lean mass, lean mass/height2 and smaller waist circumference and hip circumference (p < 0.05). In men, the association was positive (p < 0.05) between serum adiponectin and percentage of fat mass and negative between serum adiponectin and percentage of lean mass. Interestingly, in men, better cognitive function was inversely related to adiponectin (p < 0.05) while decreased anxiety was linked to a higher concentration of adiponectin in women (p < 0.05). According to the Tilburg Frailty Indicator, frail men had lower levels of adiponectin than those who were not frail (p < 0.05). Variables that predicted adiponectin concentration in multiple regression models were different for women and men. In women, lean mass and anxiety were independent negative predictors of blood adiponectin (ß = -0.363, p = 0.002; ß = -0.204, p = 0.067, respectively). In men, the Montreal Cognitive Assessment (MOCA) test was the only parameter to remain significant in the regression model (ß = -439, p = 0.015). The results of our study show that adiponectin is linked to body composition, cognitive function and anxiety in long-term nursing home residents with differential relationships by sex. Further studies should be conducted to determine whether adiponectin is a valid and reliable frailty biomarker.

Obesity parameters, physical activity, and physical fitness are correlated with serum dipeptidyl peptidase IV activity in a healthy population.

OBJECTIVE: To determine whether obesity, physical fitness, and physical activity parameters are associated with the enzymatic activity of serum dipeptidyl peptidase IV (sDPPIV) in a sample of healthy women and men. DESIGN AND METHODS: We have correlated parameters of obesity, physical fitness, and physical activity with sDPPIV activity in 374 healthy subjects (age: 60.7 ± 6.9 years, body mass index: 26.1 ± 4.1 kg/m2). Enzymatic activity was analyzed using spectrofluorimetry, body composition was assessed by impedanciometry, physical fitness data were obtained using the Senior Fitness Test, and physical activity data were collected by accelerometer. Pearson's partial correlation analysis was applied to determine the relationship between DPPIV activity and the rest of parameters and significantly correlated variables were introduced into linear regression models to predict DPPIV. RESULTS: Serum DPPIV activity was negatively associated with obesity parameters such as body mass (r = -0.112), body mass index (BMI) (r = -0.147), waist circumference (r = -0.164), waist-to-hip ratio (-0.104), and percentage of fat mass (r = -0.185). Serum DPPIV activity was positively associated with cardiovascular fitness (r = 0.138), total amount of physical activity (r = 0.153), and time spent doing light exercise (r = 0.184). Regression models revealed sex differences in enzyme activity with overall activity higher in women than in men (ß = 0.437, p < 0.001). Further, percent fat mass was an independent negative predictor of DPPIV activity (ß = -0.184, p = 0.001). Serum DPPIV activity was positively predicted based on the amount of time spent doing light physical activity (ß = 0.167, p = 0.001). CONCLUSION: Our results demonstrate that sDPPIV activity is positively associated with healthier parameters regarding fatness, fitness and physical activity.

Veratridine-sensitive Na+ channels regulate human sperm fertilization capacity.

AIMS: The sperm plasma membrane contains specific ion channels and transporters that initiate changes in Ca2+, Na+, K+ and H+ ions in the sperm cytoplasm. Ion channels are key regulators of the sperm membrane potential, cytoplasmic Ca2+ and intracellular pH (pHi), which leads to regulate motility, capacitation, acrosome reaction and other physiological processes crucial for successful fertilization. Expression of epithelial sodium channels (ENaC) and voltage-gated sodium channels (Nav) in human spermatozoa has been reported, but the role of Na+ fluxes sodium channels in the regulation of sperm cell function remains poorly understood. In this context, we aimed to analyze the physiological role of Nav channels in human sperm. MAIN METHODS: Motility and hyperactivation analysis was conducted by CASA analysis. Flow cytometry and spectrophotometry approaches were carried out to measure Capacitation, Acrosome reaction, immunohistochemistry for Tyr-residues phosporylation, [Ca2+]i levels and membrane potential. KEY FINDINGS: Functional studies showed that veratridine, a voltage-gated sodium channel activator, increased sperm progressive motility without producing hyperactivation while the Nav antagonist lidocaine did induce hyperactivated motility. Veratridine increased protein tyrosine phosphorylation, an event occurring during capacitation, and its effects were inhibited in the presence of lidocaine and tetrodotoxin. Veratridine had no effect on the acrosome reaction by itself, but was able to block the progesterone-induced acrosome reaction. Moreover, veratridine caused a membrane depolarization and modified the effect of progesterone on [Ca2+]i and sperm membrane potential. SIGNIFICANCE: Our results suggest that veratridine-sensitive Nav channels are involved on human sperm fertility acquisition regulating motility, capacitation and the progesterone-induced acrosome reaction in human sperm.

Physical activity and dietary habits related to cardiovascular risk in independent community-living older women.

A side effect of increased life expectancy is a surge in sequelae of diseases and injuries, which in turn increase the duration of life with disability among the elderly. The aim of this study was to ascertain the physical activity and nutritional parameters that better predict cardiovascular risk in a cohort of older women. A cross-sectional study was designed including 65 women able to independently perform basic activities of daily life. Data collection included anthropometric measurement, blood pressure measurement, blood analytics, objectively measurement of physical activity, and dietary assessment. We were able to generate models that explain the relationship between physical activity, diet, and these health measurement parameters. We observed that the combination of moderate physical activity and a diet including protein-rich foods as nuts, dairy, and eggs were better predictors associated with favorable changes in risk factors for cardiovascular disease than age.

The opioid peptide beta-endorphin stimulates acrosome reaction in human spermatozoa.

The acrosome reaction occurs in vivo following sperm capacitation and is essential for the acquisition of sperm fertilization ability. However, little is known about the molecular identity of the physiological acrosome reaction regulators. In addition to progesterone, which is produced by cumulus oophorus cells and known to regulate acrosome reaction by activating the specific calcium channel CatSper, endogenous opioid peptides such as beta-endorphin and met-enkephalin are present at high concentrations in the follicular fluid suggesting that the opioid system may be involved in the mechanisms regulating the acrosome reaction in humans. By using Reverse Transcription-PCR, western blot and immunofluorescence approaches, we described the presence and localization of the beta-endorphin precursor, pro-opiomelanocortinin the middle section and in flagellum of human spermatozoa, and inside the seminiferous tubules of human testis. Flow cytometry and intracellular calcium analyses showed that beta-endorphin causes an inversely dose-dependent increase in the percentage of acrosome-reacted sperm cells by a calcium-independent protein kinase C pathway. These findings are important for future studies of sperm physiology and provide new insight into the function of the opioid system as a target of fertility management.

Longitudinal study: lifestyle and cardiovascular health in health science students.

BACKGROUND: Changing lifestyle habits is considered the principal measure for the control of blood pressure and obesity. The aim of this study was to characterize the eating habits, anthropometric characteristics, physical fitness and blood pressure of students of health science degrees during the first three academic years and to explore the relation between the aforementioned parameters. METHODS: This was a longitudinal study conducted over three years on the eating habits and physical fitness of health science students (n=366) and the influence of these factors on blood pressure and obesity. RESULTS: The mean food group intakes of both female and male participants corresponded to a high consumption of lean and fatty meat, sweets and pastries and a low consumption of cereals, fruits, vegetables, olive oil, fish, nuts and vegetables. Blood pressure and obesity-related parameters were within normal ranges and did not change over the study period. Aerobic capacity values increased in men from the beginning to the end of the study, while V02max decreased in women between the first and second years. CONCLUSION: We note that, in both women and men, blood pressure values were lower when diet was high in vegetables, legumes, nuts, fish and olive oil. In both sexes, we found a negative correlation between aerobic capacity and systolic and diastolic blood pressure and a positive correlation between obesity and blood pressure. The pattern of the eating habits and changes therein were different in young women and men, the former being focused on improving their diet and the latter on improving their physical fitness.

Objetivo: Cambiar los hábitos de vida se considera la principal medida para el control de la presión arterial y la obesidad. El objetivo de este estudio fue caracterizar los hábitos alimentarios, características antropométricas, condición física y la presión arterial de los estudiantes de grados de ciencias de la salud durante los tres primeros años académicos y analizar la relación entre los parámetros antes mencionados. Métodos: El estudio fue un estudio longitudinal llevado a cabo durante los tres primeros años de universidad, donde se midieron los hábitos alimenticios y la condición física de los estudiantes de grados de ciencias de la salud (n = 366) y la influencia de estos factores sobre la presión arterial y la obesidad. Resultados: El consumo de alimentos tanto de mujeres como de hombres, se correspondió con un consumo excesivo de carne magra y grasa, dulces y pasteles; y un bajo consumo de cereales, frutas, verduras, aceite de oliva, pescado, frutos secos y legumbres. Los parámetros de la presión arterial y de la obesidad se sitúan dentro de la normalidad y no varían a lo largo del periodo de estudio. Los valores de la capacidad aeróbica aumentaron en los hombres desde el principio hasta el final del estudio, mientras que V02max disminuyó en las mujeres entre el primer y segundo año. Conclusiones: Observamos que tanto en las mujeres como en los hombres, los valores de presión arterial fueron más bajos cuando la dieta era rica en verduras, legumbres, frutos secos, pescados y aceite de oliva. En ambos sexos, se encontró una correlación negativa entre la capacidad aeróbica y la presión arterial sistólica y diastólica y una correlación positiva entre la obesidad y la presión arterial. El patrón de los hábitos alimentarios y los cambios a lo largo de los tres años, fueron diferentes en las mujeres y los hombres. Las mujeres se centran más en la mejora de su dieta y los hombres en la mejora de su condición física.

Longitudinal study: lifestyle and cardiovascular health in health science students / Estudio longitudinal: estilos de vida y salud cardiovascular de estudiantes de ciencias de la salud

Background: Changing lifestyle habits is considered the principal measure for the control of blood pressure and obesity. The aim of this study was to characterize the eating habits, anthropometric characteristics, physical fitness and blood pressure of students of health science degrees during the first three academic years and to explore the relation between the aforementioned parameters. Methods: This was a longitudinal study conducted over three years on the eating habits and physical fitness of health science students (n=366) and the influence of these factors on blood pressure and obesity. Results: The mean food group intakes of both female and male participants corresponded to a high consumption of lean and fatty meat, sweets and pastries and a low consumption of cereals, fruits, vegetables, olive oil, fish, nuts and vegetables. Blood pressure and obesity-related parameters were within normal ranges and did not change over the study period. Aerobic capacity values increased in men from the beginning to the end of the study, while V02 max decreased in women between the first and second years. Conclusion: We note that, in both women and men, blood pressure values were lower when diet was high in vegetables, legumes, nuts, fish and olive oil. In both sexes, we found a negative correlation between aerobic capacity and systolic and diastolic blood pressure and a positive correlation between obesity and blood pressure. The pattern of the eating habits and changes therein were different in young women and men, the former being focused on improving their diet and the latter on improving their physical fitness (AU)

Objetivo: Cambiar los hábitos de vida se considera la principal medida para el control de la presión arterial y la obesidad. El objetivo de este estudio fue caracterizar los hábitos alimentarios, características antropométricas, condición física y la presión arterial de los estudiantes de grados de ciencias de la salud durante los tres primeros años académicos y analizar la relación entre los parámetros antes mencionados. Métodos: El estudio fue un estudio longitudinal llevado a cabo durante los tres primeros años de universidad, donde se midieron los hábitos alimenticios y la condición física de los estudiantes de grados de ciencias de la salud (n = 366) y la influencia de estos factores sobre la presión arterial y la obesidad. Resultados: El consumo de alimentos tanto de mujeres como de hombres, se correspondió con un consumo excesivo de carne magra y grasa, dulces y pasteles; y un bajo consumo de cereales, frutas, verduras, aceite de oliva, pescado, frutos secos y legumbres. Los parámetros de la presión arterial y de la obesidad se sitúan dentro de la normalidad y no varían a lo largo del periodo de estudio. Los valores de la capacidad aeróbica aumentaron en los hombres desde el principio hasta el final del estudio, mientras que V02 max disminuyó en las mujeres entre el primer y segundo año. Conclusiones: Observamos que tanto en las mujeres como en los hombres, los valores de presión arterial fueron más bajos cuando la dieta era rica en verduras, legumbres, frutos secos, pescados y aceite de oliva. En ambos sexos, se encontró una correlación negativa entre la capacidad aeróbica y la presión arterial sistólica y diastólica y una correlación positiva entre la obesidad y la presión arterial. El patrón de los hábitos alimentarios y los cambios a lo largo de los tres años, fueron diferentes en las mujeres y los hombres. Las mujeres se centran más en la mejora de su dieta y los hombres en la mejora de su condición física (AU)

OBLA is a better predictor of performance than Dmax in long and middle-distance well-trained runners.

AIM: The main purpose of this study was to investigate if the lactate threshold estimated by the maximal deviation method (LTDmax) and the onset of blood lactate accumulation speed (LTOBLA) are good correlates of middle- and long-distance running performance in well-trained endurance runners. METHODS: Eleven long- and eleven middle-distance runners participated in this study. All participants completed a maximal incremental running test on a treadmill to determine maximal physiological variables and velocities corresponding to LTDmax and LTOBLA (4 mmol·L-1 of lactate concentration). The relationships between LTDmax, LTOBLA and the best 10-km (S10km) and 3-km (S3km) race pace were analyzed in the long- and middle distance runners, respectively. RESULTS: The velocities for LTDmax and LTOBLA were 17.0±0.7 km·h-1 and 17.5±1.3 km·h-1 for the long-distance runners and 16.9±1.1 km·h-1 and 17.4±1.3 km·h-1 for the middle-distance runners. A positive linear relationship was found between LTDmax and S10km (r=0.873, P<0.001), as well as between LTOBLA and S10km (r=0.919, P<0.001) in the long-distance runners. Similarly, LTDmax and LTOBLA were significantly correlated with S3km in the middle-distance runners (r=0.825, P<0.01 and r=0.849, P<0.001, respectively). CONCLUSION: These results indicate that both LTOBLA and LTDmax are highly associated to running performance according to S10km and S3km in well-trained long- and middle-distance runners. Thus, we conclude that competitive middle- and long-distance athletes may find these measures useful to monitor running performance within 3 weeks of laboratory testing.

Interaction effects of stride angle and strike pattern on running economy.

This study aimed to investigate the relationship between stride angle and running economy (RE) in athletes with different foot strike patterns. 30 male runners completed 4 min running stages on a treadmill at different velocities. During the test, biomechanical variables such as stride angle, swing time, contact time, stride length and frequency were recorded using an optical measurement system. Their foot strike pattern was determined, and VO2 at velocities below the lactate threshold were measured to calculate RE. Midfoot/forefoot strikers had better RE than rearfoot strikers (201.5±5.6 ml · kg(-1) · km(-1) vs. 213.5±4.2 ml · kg(-1) · km(-1)respectively; p=0.019). Additionally, midfoot/fore-foot strikers presented higher stride angles than rearfoot strikers (p=0.043). Linear modelling analysis showed that stride angle is closely related to RE (r=0.62, p<0.001) and that the effect of stride angle on RE was different in the 2 groups. From an arbitrary value of 4°, a rearfoot strike pattern is likely to be more economical, whereas at any lower degree, the midfoot/forefoot strike pattern appears to be more desirable. A biomechanical running technique characterised by high stride angles and a midfoot/forefoot strike pattern is advantageous for a better RE. Athletes may find stride angle useful for improving RE.

Differences in ground contact time explain the less efficient running economy in north african runners.

The purpose of this study was to investigate the relationship between biomechanical variables and running economy in North African and European runners. Eight North African and 13 European male runners of the same athletic level ran 4-minute stages on a treadmill at varying set velocities. During the test, biomechanical variables such as ground contact time, swing time, stride length, stride frequency, stride angle and the different sub-phases of ground contact were recorded using an optical measurement system. Additionally, oxygen uptake was measured to calculate running economy. The European runners were more economical than the North African runners at 19.5 km · h(-1), presented lower ground contact time at 18 km · h(-1) and 19.5 km · h(-1) and experienced later propulsion sub-phase at 10.5 km · h(-1),12 km · h(-1), 15 km · h(-1), 16.5 km · h(-1) and 19.5 km · h(-1) than the European runners (P < 0.05). Running economy at 19.5 km · h(-1) was negatively correlated with swing time (r = -0.53) and stride angle (r = -0.52), whereas it was positively correlated with ground contact time (r = 0.53). Within the constraints of extrapolating these findings, the less efficient running economy in North African runners may imply that their outstanding performance at international athletic events appears not to be linked to running efficiency. Further, the differences in metabolic demand seem to be associated with differing biomechanical characteristics during ground contact, including longer contact times.

Regulation of human sperm motility by opioid receptors.

The endogenous opioid system has been reported to have important functions in human reproduction. Practically all the components of this peptide system have been discovered in human sperm cells, but their functions in these cells are far from being well understood. In the present work, we report the effects of opioid agonism and antagonism on human sperm motility, a parameter which is crucially associated with male fertility. Morphine (10(-7) M), a µ- opioid receptor agonist, decreased both the percentage of motile progressive sperm and three measured velocities without altering the linearity, straightness or vigour of sperm cells. This effect was reversed by naloxone. Higher doses of morphine did not have further effects on the measured parameters. The incubation of sperm cells with the δ-opioid receptor agonist D-penicillamine (2,5)-enkephalin did not affect sperm cell motility. However, naltrindole, a specific δ-receptor antagonist, reduced the linear and curvilinear velocities, as well as linearity, straightness and the amplitude of head displacement, and beat frequency. In summary, our results indicate that the endogenous opioid system may regulate opioid motility in vitro. These finding suggest that the endogenous opioid system could be useful as a biochemical tool for the diagnosis and treatment of male infertility.

Selection of young soccer players in terms of anthropometric and physiological factors.

AIM: The aim of this paper was to describe the anthropometric and physiological characteristics of young soccer players (14-17 years old) which were associated with their being successful or not as soccer players. METHODS: Somatotype and body composition was calculated by measuring skinfolds, limb circumferences and joint diameters. VO(2max) was estimated by the Astrand's Test. Sprint, jump and endurance tests were also performed. RESULTS: The most relevant differences were obtained between selected and non-selected players belonging to the 14-year-old team. Selected players were taller, heavier, leaner and faster and they had higher absolute or relative VO(2max). In addition, a higher % of selected players was found among those born during the first 6 months of the year. In the rest of the teams, the agility was better in selected than in non-selected players. At later ages, there was also a predominance of players born during the first 6 months of the year. CONCLUSIONS: These results indicate that around the time of puberty, parameters associated with physical maturity such as height, size, speed, VO(2max), or chronological age are important to determine the success of a soccer player. At older ages, other factors such as agility seem to be more important. Nevertheless, players born in the 1st semester of the year are also more frequent in the older teams. These findings should be taken into account by trainers and coaches, in order to avoid biasing their selection choices.

Distribution of peptidase activity in teleost and rat tissues.

Peptides play important roles in cell regulation and signaling in many tissues. The actions of peptides are regulated by peptidases. Although the activity of these enzymes has been thoroughly characterized in mammals, little is known about their presence or function in fish. In the present study, we compared the activity of several peptidases in selected tissues (pituitary gland, different brain areas, kidney and gills) of the gilthead sea bream and rainbow trout with that found in similar rat tissues (lungs studied in place of gills). Soluble puromycin-sensitive aminopeptidase showed the highest values in the pituitary gland of the sea bream, whereas the membrane-bound form was found to be more active in the trout kidney. Very high levels of activity of aminopeptidase N were detected in trout and sea bream plasma. In contrast, the highest levels of activity of aminopeptidase B were found in rat tissues, with the exception of the gills of the trout. Aminopeptidase N levels tended to be higher in sea bream tissues with respect to those of trout. In contrast, the level of activity of aminopeptidase B was found to be consistently much higher in trout tissues than in those of the sea bream. Prolyl endopeptidase activity was principally detected in the pituitary gland and in the brain areas of teleosts. These differences between species could be related to different mechanisms of osmoregulation in saltwater- and in freshwater-adapted fish.

Aminopeptidase activity in the postmortem brain of human heroin addicts.

Several studies have reported that the chronic administration of opioids induces changes in the biosynthesis of endogenous opioid peptides or their precursors in specific brain regions of the adult central nervous system. However, little is known about the catabolic regulation of opioid peptides and its contribution to neuroadaptative changes underlying drug addiction. In the present study, we have analyzed the activity of two enkephalin-degrading enzymes (puromycin-sensitive aminopeptidase or PSA and aminopeptidase N or APN) and two functionally different, soluble aminopeptidases (aminopeptidase B and aspartyl-aminopeptidase) in postmortem samples of prefrontal cortex and caudate nucleus of eight human heroin addict brains and eight matched-controls. Enzyme activities were fluorimetrically measured using beta-naphthylamide derivatives. An increase in the activity of soluble PSA in the prefrontal cortex of heroin abusers was observed (heroin addict group: 51,452+/-3892 UAP/mg protein versus control group: 42,003+/-2597 UAP/mg protein; P<0.05), while the activity of the other peptidases in both brain regions remained unaltered. This result agrees with previous findings in morphine-tolerant rats, and indicates that soluble PSA may be involved in neurobiological processes which underlie heroin addiction.

Peptide metabolism and the control of body fluid homeostasis.

In this paper, we review our current understanding of the medicinal chemistry of the major peptide systems, which influence body fluid homeostasis. Electrolytes play pivotal roles in intra- and intercellular communication, acid-base equilibrium and, when bound to several macromolecules, they regulate a myriad of enzymatic proteins, receptors and transcription factors. Cell turgor influences the plasma membrane, which activates mechanically-gated ion channels or mechanoreceptors, and the expression of a number of genes which underlie long-term metabolic responses to hormones, substrates and reactive oxygen intermediates. The altered kinetics and enzymatic cleavage of peptides during water-electrolyte imbalance can contribute to cardiac and renal damage associated with elevated blood pressure. Identification of the enzymes which are responsible for cleavage, together with emerging information about the mechanisms of action and structures of regulatory and effector peptides, has laid a foundation for the discovery of novel drugs, some of which are in use or are now undergoing evaluation in experimental trials. The development of models of hydrosaline challenge with relative efficiency to induce selective water-electrolyte imbalance has permitted the identification of kallikrein-kinin, renin-angiotensin-aldosterone, vasopressin-oxytocin, thyrotropin-releasing hormone and luteinizing hormone-releasing hormone as susceptible substrates. At present, the angiotensin-I converting enzyme inhibitors are well-known efficacious, orally active, blood pressure-lowering agents which have been used in hypertensive patients. In addition to several new analogues of this class of drug, some selective dual inhibitors of angiotensin-I converting enzyme and neutral endopeptidase and inhibitors of aminopeptidases are now also being rationally assayed and their beneficial effects on hypertension and hydromineral balance indicate that this type of drug may have powerful therapeutic effects for disorders of body fluid homeostasis.

Effect of the disruption of body fluid balance on pyroglutamyl aminopeptidase (Type-1) in rat brain structures.

The activity of soluble and membrane-bound pyroglutamyl aminopeptidase Type-1 (PAP I) was evaluated in the hypothalamus, hippocampus, thalamus, brain cortex, and pituitary gland of rats after applying certain hydromineral challenges. Compared to euhydrated rats, decreased enzyme activity was found in the hypophysis of rats deprived of water for 48 h, or rats drinking ad libitum hypertonic sodium chloride solution (2%) for 6 days or distilled water for 6 days and then submitted to acute water overload. PAP I cleaves the pGlu-amino acid bond of neuropeptides such as thyroliberin, luliberin, neurotensin, and bombesin. The decay of particulate PAP I activity may cause an increase of these pyroglutamate peptides in the whole pituitary. Although the deleterious or pro-homeostatic influence of this decay remains to be elucidated, the present data provide evidence for the involvement of this enzyme activity at this anatomical location in the water-electrolyte imbalance.