Biomedical subjects

A Salvador

Publications and source records attributed to A Salvador.

At least 19 recordsLinked to original sources

PubMed2003

Research trends in the journal Hormones and Behavior (1987-2000).

As a continuation of the study carried out by Svare more than 15 years ago (Horm. Behav. 22 (1988), 139) and to determine the tendencies of the evolution of behavioral endocrinology since then, our aim was to extend his work until 2000, assuming that the journal Hormones and Behavior would be representative of the field at large. To study this 14-year period and compare it with Svare's data, we kept the same criteria and categories, behavioral patterns, and species. Our results show that "sexual behavior" in "rodents" is still the most extensive field studied by behavioral endocrinologists, although frequency of other topics is increasing, above all "aggressive and emotional responses," and especially the interrelationships between them. Interestingly, studies dedicated to humans are slowly becoming more common. In addition to these analyses, we obtained the several citations received by a randomly selected sample of articles during the period that was divided by the number of years when the articles can be potentially cited. These ratios revealed that research on "humans," within the category of species, and on "memory, learning, and conditioning" and "aggressive and emotional responses," within the behavioral categories, present the highest visibility in the literature. Furthermore, this analysis was complemented with information about the main receptor journals of the papers published in Hormones and Behavior, classified by the same categories. All these data, although limited by the analysis of only one journal, permitted us to reflect on whether the evolution tendencies formulated by Beach (Horm. Behav. 15 (1981), 325) for this discipline were applicable to the period studied, thus confirming its status as a mature discipline for the last quarter of the 20th century.

Animals↗

PubMed2003

Salivary testosterone is related to both handedness and degree of linguistic lateralization in normal women.

The aim of this study was to test the hypothesis that individual differences in testosterone (T) are associated with different patterns of linguistic lateralization and hand preference. Twenty left-handed (LH) and 19 right-handed (RH) women filled in a handedness questionnaire and performed a consonant-vowel dichotic listening test (DL-CV). Salivary T was measured by radioimmunoassay (RIA). LH women showed significantly lower mean salivary T than RH women. T levels were negatively correlated with the absolute value of the DL laterality index. Subjects with right ear advantage (REA) were classified into strongly and weakly lateralized following Wexler et al. method (Brain Lang. 13 (1981) 13). When taking into account hand preference, a pattern emerged in that RH-strongly lateralized and LH-weakly lateralized women showed similar T levels. The lowest level appeared for LH-strongly lateralized women and the highest for RH-weakly lateralized women, being significantly different from each other. The results are discussed in terms of several theories that have proposed a link between testosterone and cerebral lateralization.

Adult↗

PubMed2003

Anticipatory cortisol, testosterone and psychological responses to judo competition in young men.

This study compares the anticipatory hormonal and psychological responses of 17 male judo players to an official competition with the data obtained during eight resting sessions carried out at the same time of day, throughout an entire sports season. Testosterone (T) and cortisol (C) levels were determined 1 h and 30 min before competition, and mood, anxiety and expectancies were also evaluated. C levels and anxiety scores were concurrently higher before the contest than in resting conditions; however, non-significant correlations between them were found. The anticipatory T response was not significant for the whole group. However, one group of subjects did display T increases, higher C levels, and higher motivation to win scores than the other group. Furthermore, this group also obtained a better outcome. Thus, this hormonal pattern and its relationships with psychological variables suggest an adaptive psychobiological response to a competition. Results are discussed in the context that neuroendocrine response to competition is associated with cognitive appraisal.

Adaptation, Psychological↗

PubMed2002

Cocaine-induced locomotor activity is enhanced by exogenous testosterone.

Anabolic-androgenic steroids are synthetic derivatives of testosterone, which are increasingly abused by adolescent populations who also abuse psychoactive substances. All these compounds lead to complex behavioral syndromes and the effects of their interactions remain unclear. The main aim of the present study was to determine the influence of testosterone on the locomotor activity-promoting effect of cocaine on male mice in an open field. In the three experiments, animals received two injections: firstly, testosterone or peanut oil, and secondly, cocaine or saline solution. In Experiments 1 and 2, testosterone (or oil) and cocaine (or saline) were injected 45 and 10 min, respectively, prior to activity recording. In the first experiment, we studied the effects of testosterone (2 mg/kg) on locomotor activity induced by different doses of cocaine (2, 4, 8, 10 or 12 mg/kg). In Experiment 2, we explored the effects of supraphysiological doses of testosterone (2, 6, 10 or 14 mg/kg) on animals treated with 10 mg/kg cocaine. Finally, in the third experiment, 14 mg/kg testosterone or vehicle was administered 15, 30, 45 or 75 min before activity data collection to animals that received 10 mg/kg cocaine or saline. Testosterone itself had no effects on spontaneous locomotor activity and, as was expected, cocaine increased locomotor activity dose-dependently. Given together, testosterone enhanced the cocaine-induced hyperactivity although not dose-dependently, the highest effects being found 45 min after testosterone injection. The present study confirmed the existence of an interaction between testosterone and cocaine at the central nervous system.

Animals↗

PubMed2002

Introducing printed postpartum orders for measles-mumps-rubella vaccination: a qualitative study.

OBJECTIVE: After introducing printed postpartum orders at our centre, we observed a large increase in measles-mumps-rubella (MMR) vaccination of susceptible women. The objective of this study was to ascertain factors responsible for the success of our approach and to identify potential obstacles so as to facilitate the implementation of similar policies at other hospitals. METHODS: For this qualitative study, taped semi-structured interviews were carried out with physicians, nurses, and a ward clerk regarding their views on postpartum MMR vaccination and on various aspects of implementing a printed postpartum order sheet that included MMR vaccination of susceptible women. Interviews were transcribed and the responses classified by theme. Thematic analysis was used to identify strengths and weaknesses of this approach. RESULTS: Following implementation of printed postpartum orders that included MMR vaccination of susceptible women, the proportion of eligible women vaccinated increased from 12.1 to 81.7% (risk ratio 6.8, 95% confidence interval [CI] 3.3, 13.7). While the physician and nursing staff broadly supported this initiative, we identified the need for changes in obstetrical care and documentation: most importantly, a comprehensive protocol with supporting information and guidelines should be provided for postpartum nurses; and a system must be in place to ensure that the completed antenatal record, including screening test results, be available in the expected hospital of delivery by the late second trimester. CONCLUSION: Previously undocumented claims that standing orders for postpartum MMR vaccination will increase the rate of vaccination of susceptible women have now been substantiated at one centre. Nevertheless, careful infrastructure and systems changes are required to ensure implementation of such orders.

Female↗

PubMed2001

Hydroperoxyl, superoxide and pH gradients in the mitochondrial matrix: a theoretical assessment.

The negative surface charge of many cellular membranes concentrates protons and rarefies superoxide in their vicinity. It was speculated that the low pH near membranes should facilitate superoxide protonation, thereby concentrating hydroperoxyl radical in this region. This process would exacerbate both lipid peroxidation and the transfer of oxidative damage between cellular compartments, as hydroperoxyl is a good initiator of lipid peroxidation and permeates lipid bilayers. Surface-charge-enhancement of hydroperoxyl production in mitochondria--which are main intracellular sources of superoxide--should be particularly relevant. Using a simple model of superoxide metabolism in the mitochondrial matrix, we calculated the gradients of pH, superoxide, and hydroperoxyl, and assessed the previous hypothesis in the light of available experimental data. The following predictions ensued: (i) Near the mitochondrial inner membrane, gradients of superoxide concentration with amplitude up to 36% of the maximal concentration, and pH gradients of up to 0.19 units between membrane and bulk. (ii) These electrostatically induced gradients die out within approximately 4 nm of the membrane. (iii) At high (hundreds of nanometres) inter-cristae separations, owing to enzyme-catalyzed dismutation of superoxide, both superoxide and hydroperoxyl become rarefied towards the midpoint between cristae. (iv) Surface charge should neither enhance superoxide protonation nor concentrate hydroperoxyl near biological membranes.

Electrophysiology↗

PubMed2001

Chiral supercritical fluid chromatography on porous graphitic carbon using commercial dimethyl beta-cyclodextrins as mobile phase additive.

Using dimethylated-beta-cyclodextrin mixtures (MeCD) as chiral selectors in CO2-polar modifier mobile phase and porous graphitic carbon as solid-phase, chiral supercritical (or subcritical) fluid chromatography was performed. The adsorbed quantity of MeCD onto the porous graphitic carbon (Hypercarb) was measured for various chiral selector concentrations using the breakthrough method with evaporative light scattering detector. The effects of MeCD concentration in the mobile phase, the nature of the polar modifier, the outlet pressure, the column temperature and the nature of the commercial MeCD mixture on the retention and the enantioselectivities were studied. For a given solute, the enantioselectivity is greatly dependent on the commercial MeCD mixture used. The retention mechanism was also studied. From the data, we find that the dominant mechanism for the chiral discrimination is the diastereoisomeric complexation in the mobile phase.

Chromatography, Supercritical Fluid↗

PubMed2001

Determination of the UV filters worldwide authorised in sunscreens by high-performance liquid chromatography. Use of cyclodextrins as mobile phase modifier.

Simultaneous determination of organic UV filters worldwide authorised in sunscreen formulations was performed by HPLC with UV spectrophotometric detection. The filters determined were: benzophenone-4, benzophenone-3, butyl methoxydibenzoylmethane, octyl dimethyl PABA, octyl methoxycinnamate, homosalate and octyl salicylate. A C18 stationary phase and an isocratic mobile phase of ethanol-water-acetic acid (70:29.5:0.5) containing 65.4 mM of hydroxypropyl-beta-cyclodextrin, were used with a flow-rate of 0.6 ml/min. UV measurements were carried out at 313 nm. The time required for the analysis was 20 min and the limits of detection were between 1.5 and 2.3 mg/l. The procedure proposed provides a green analytical method with a basic instrumental configuration, it is fast and accurate and does not involve highly toxic organic solvents.

Chromatography, High Pressure Liquid↗

PubMed2001

Efficient flow injection and sequential injection methods for spectrophotometric determination of oxybenzone in sunscreens based on reaction with Ni(II).

Spectrophotometric determination of a widely used UV-filter, such as oxybenzone, is proposed. The method is based on the complexation reaction between oxybenzone and Ni(II) in ammoniacal medium. The stoichiometry of the reaction, established by the Job method, was 1:1. Reaction conditions were studied and the experimental parameters were optimized, for both flow injection (FI) and sequential injection (SI) determinations, with comparative purposes. Sunscreen formulations containing oxybenzone were analyzed by the proposed methods and results compared with those obtained by HPLC. Data show that both FI and SI procedures provide accurate and precise results. The ruggedness, sensitivity and LOD are adequate to the analysis requirements. The sample frequency obtained by FI is three-fold higher than that of SI analysis. SI is less reagent-consuming than FI.

Ammonia↗

PubMed2001

Determination of UV-filters in sunscreens by HPLC.

Simultaneous determination of six internationally authorised organic UV-filters in sunscreen formulations was performed by HPLC with UV spectrophotometric detection. The filters determined were: sulisobenzone, oxybenzone, octyl dimethyl PABA, octyl methoxycinnamate, octyl salicylate and homosalate. A C18 stationary phase and a mobile phase of ethanol water acetic acid (70:29.5:0.5) were used with a flow rate of 0.5 mL/min. UV measurements were carried out at 313 nm. The time required for the analysis was 25 min and the limits of detection were between 0.2 and 2 mg/L, except for sulisobenzone, which gave a limit of detection of 20 mg/L. The procedure proposed provides an accurate, fast and green analytical method, that does not involve toxic organic solvents.

Chromatography, High Pressure Liquid↗

PubMed2001

Psychophysiological responses to the Stroop Task after a maximal cycle ergometry in elite sportsmen and physically active subjects.

Physical fitness moderates the psychophysiological responses to stress. This study attempts to determine whether the degree of fitness could affect the response to physical and psychological stress after comparing two groups of men with good physical fitness. Saliva samples from 18 elite sportsmen, and 11 physically active subjects were collected to determine hormonal levels after carrying out a maximal cycle ergometry. Heart rate and skin conductance level were continuously recorded before, during, and after a modified version of the Stroop Color-Word Task. With similar scores in trait anxiety and mood, elite sportsmen had lower basal salivary testosterone, testosterone/cortisol ratio, and HR before an ergometric session than physically active subjects, but no differences were found in salivary cortisol and blood pressure. Salivary testosterone and cortisol responses were lower and testosterone/cortisol ratio responses higher in elite sportsmen. During the Stroop Task, elite subjects showed lower heart rate and skin conductance level over the entire measurement period, and greater heart rate recovery with respect to the baseline values than physically active subjects. The effects of two standardised laboratory stressors on a set of psychophysiological variables were different when elite sportsmen and physically active subjects were compared.

Adult↗

PubMed2001

Gender differences in cardiovascular and electrodermal responses to public speaking task: the role of anxiety and mood states.

Gender moderates psychophysiological responses to stress. In addition to the hormonal background, different psychological states related to social stressors, such as anxiety and mood, could affect this response. The purpose of this study was to examine the existence of gender differences in the cardiovascular and electrodermal responses to a speech task and their relationship with anxiety and the mood variations experienced. For this, non-specific skin conductance responses (NSRs), heart rate (HR), and finger pulse volume (FPV) were measured at rest, and during preparation, task and recovery periods of an academic career speech in undergraduate men (n=15) and women (n=23), with assessment of changes in the state version of the State-Trait Anxiety Inventory (STAI-S) and in the Profile of Mood States (POMS) questionnaires. Men and women did not differ in trait anxiety, hostility/aggressiveness, or in the appraisal of the task, which were evaluated with the trait version of the State-Trait Anxiety Inventory (STAI-T), the Buss and Durkee Hostility Inventory (BDHI), and a self-report elaborated by ourselves, respectively. Women had higher FPV in all periods except during the task, and were more reactive to the stressor in state anxiety, and in the amplitude of NSRs. No gender differences for HR and for the frequency of NSRs were found. Anxiety and mood states were differently related to cardiovascular and electrodermal measurements in men and women. Further studies should consider the hormonal variations in addition to the psychological dimensions, in order to offer a more integrative perspective of the complex responses to stress.

Adult↗

PubMed2001

Effects of the luteinising hormone-releasing hormone (LH-RH) agonist leuprolide on adenylyl cyclase regulation through G-protein coupled receptors in rat ventral prostate.

Luteinising hormone-releasing hormone (LH-RH) agonists are widely used for the therapy of advanced prostate cancer through the suppression of testosterone secretion. Furthermore, recent studies indicate the existence of prostate LH-RH receptors coupled to signalling pathways resulting in direct antiproliferative effects. In order to shed light on the mechanisms through which these compounds inhibit prostate cell growth, we investigated the effects of leuprolide (a LH-RH agonist) treatment of rats compared with the effects of surgical castration on the behaviour of G-protein coupled receptors acting through adenylyl cyclase in the ventral prostate. Important decreases of both plasma testosterone levels and ventral prostate weight were observed 5 weeks after subcutaneous (s.c.) injection of a leuprolide-depot preparation (1.5 mg/kg body weight (b.w.)) or 5 days after bilateral gonadectomy. However, leuprolide treatment increased the number of vasoactive intestinal peptide (VIP) receptors and the ability of this neuropeptide to stimulate adenylyl cyclase activity in prostate membranes, whereas surgical castration decreased both parameters. Moreover, leuprolide resulted in significant increases of prostate alpha(s) and alpha(i1-3) (but not alpha(i1) and beta) G-protein levels, while the four G-protein subunits were overexpressed after gonadectomy. The estimation of alpha(s) and alpha(i) activity by experiments with Gpp[NH]p and forskolin indicated a potentiation of the two arms of adenylyl cyclase regulation in leuprolide-treated rats. Present observations suggest that leuprolide treatment leads to an antimitogenic response by acting mainly through the activation of Gi proteins negatively coupled to adenylyl cyclase.

Adenylyl Cyclases↗

PubMed2001

Stopped-flow Fourier-transform infra-red spectrometric speciation of glycolic and lactic acids in cosmetic formulations.

The dermatological activity of cosmetic formulations containing alpha-hydroxyacids depends on their different chemical forms, and it is therefore useful to determine these species in the finished products. In the present report a new procedure for studying the protonation equilibria of glycolic and lactic acids by stopped-flow Fourier-transform infra-red (FTIR) spectrometry is described. The procedure was validated for use in the speciation of glycolic and lactic acids in cosmetic formulations, with preferential attention given to glycolic acid, which is the most widely used. Species of these alpha-hydroxyacids can be approximately determined at different pHs and the total content of each alpha-hydroxyacid can be accurately determined (according to the Student t-test at 5% significance level). The recovery of the total content of glycolic acid from commercial cosmetic formulations was 101+/-4%. The RSD of the determinations of the total content and those of the species was of the order of 2-7%.

Cosmetics↗

PubMed2001

Sequential injection spectrophotometric determination of oxybenzone in lipsticks.

A sequential injection (SI) procedure for the spectrophotometric determination of oxybenzone in lipsticks is reported. The colorimetric reaction between nickel and oxybenzone was used. SI parameters such as sample solution volume, reagent solution volume, propulsion flow rate and reaction coil length were studied. The limit of detection was 3 microg ml(-1). The sensitivity was 0.0108+/-0.0002 ml microg(-1). The relative standard deviations of the results were between 6 and 12%. The real concentrations of samples and the values obtained by HPLC were comparable. Microwave sample pre-treatment allowed the extraction of oxybenzone with ethanol, thus avoiding the use of toxic organic solvents. Ethanol was also used as carrier in the SI system. Seventy-two injections per hour can be performed, which means a sample frequency of 24 h(-1) if three replicates are measured for each sample.

Benzophenones↗

PubMed2001

Relationships between recall of perceived exertion and blood lactate concentration in a judo competition.

Relationships between perceived exertion and blood lactate have usually been studied in laboratory or training contexts but not in competition, the most important setting in which sports performance is evaluated. The purpose of this study was to examine the relationships between psychological and physiological indices of the physical effort in a competition setting, taking into account the duration of effort. For this, we employed two Ratings of Perceived Exertion (RPE and CR-10) and lactic acid plasma concentration as a biological marker of the effort performed. 13 male judo fighters who participated in a sports club competition provided capillary blood samples to assay lactate concentrations and indicated on scale their Recall of Perceived Exertion in the total competition and again in just the Last Fight to compare the usefulness of RPE and CR-10 in assessing discrete bouts of effort and a whole session. Analysis showed that perceived exertion or the effort made during the whole competition was positively and significantly related to maximal lactate concentration and lactate increase in competition, thus extending the validity of this scale to sports contests. The Recall of Perceived Exertion scores were not significantly correlated with the duration of effort.

Adult↗

PubMed2000

Chromium speciation in liquid matrices: a survey of the literature.

A thorough review of the literature published (1983 - March 1999) on chromium speciation in liquid samples is presented, and analytical techniques used in the 404 articles are summarized. The discussion focuses on atomic spectrometric techniques, which are mainly employed for chromium speciation in liquid matrices (134 articles). Details on the type of pretreatment, species, samples, techniques and analytical features of the methodologies proposed are given.

Journal Article↗

PubMed2000

Synergism analysis of biochemical systems. I. Conceptual framework.

The detection of synergisms--deviations from additive or linear behaviour--is often an important step in uncovering mechanisms of biochemical processes. Yet, a theoretical background for systemic analysis of synergisms in metabolic networks is lacking. Based on suitable mathematical models, such a theoretical approach should allow predicting synergisms and analysing what mechanistic features contribute to specific synergisms. This work presents a conceptual framework and formalism that fulfil these purposes. The synergism between perturbations of a pair of parameters is quantified as the difference between the response to the simultaneous perturbation of both parameters and the sum of the individual responses to the perturbations of each parameter. A generalisation measures deviations from multiplicative or power-law behaviour. These deviations were called log-synergisms, as in logarithmic coordinates they are quantified in the same way as the synergisms are in Cartesian coordinates. For small perturbations, synergisms and log-synergisms are approximately proportional to the second derivatives (in Cartesian and logarithmic coordinates, respectively) of the observable to the perturbed parameter(s). These derivatives, here called synergism or log-synergism coefficients, measure how steeply the responses diverge from linearity/additivity or power-law/multiplicativity. The formalism now presented allows evaluating (log-)synergism coefficients for systemic steady-state responses, and relates these coefficients to intrinsic kinetic properties of the underlying processes. A robust homeostasis of metabolite concentrations requires that these have moderate systemic log- and relative-synergism coefficients.

Enzymes↗