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Biomedical subjects

S Martín

Publications and source records attributed to S Martín.

At least 37 records · Page 2Linked to original sources
PubMed2000

A fast one-step reverse transcription and polymerase chain reaction (RT-PCR) amplification procedure providing highly specific complementary DNA from plant virus RNA.

Reverse transcription and polymerase chain reaction (RT-PCR) are being used increasingly for detection and typing RNA viruses. For this purpose, metal block thermal cyclers (MBTC) are considered to provide higher DNA yield, whereas air thermal cyclers (ATC) allow PCR amplification in a much shorter time. A fast ATC protocol (0 s denaturation, 0 s annealing, and 4-8 s elongation) was developed to amplify genomic segments from two RNA viruses, which allowed increasing the number of cycles without a parallel increase of non-specific DNA fragments. Under these conditions, 80-90 cycles with the ATC provided a DNA yield close to that of a standard 40-cycles MBTC protocol in about half the time. The DNA synthesised by the new procedure was highly specific and could be cloned readily.

Citrus↗
PubMed2000

Decreased endogenous antioxidant enzymatic status in essential hypertension.

Several lines of evidence suggest that patients with essential hypertension have impaired endothelial nitric oxide activity and increased superoxide anion production. However, the mechanisms underlying these abnormalities remain unknown. We measured enzymatic superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities in erythrocytes and whole blood, respectively, in 30 newly-diagnosed, normolipidaemic untreated mild hypertensive patients and in 164 age-matched healthy controls. SOD and GPX activities in hypertensive patients (806 +/- 225 U/Hb.g and 5491 +/- 2073 U/L, respectively) were significantly lower than in the control group (931 +/- 202 U/Hb.g and 6669 +/- 1560 U/L, respectively) (P < 0.005). No significant association was found between these antioxidant enzyme activities and blood pressure in normotensive controls. In the hypertensives, only log-transformed SOD activity showed a significant negative correlation with systolic and diastolic blood pressure (r = 0.37, P < 0.05; r = 0.64, P < 0.0001, respectively). The low endogenous antioxidant enzyme activities observed may in turn result in decreased superoxide anion removal leading to nitric oxide inactivation. Journal of Human Hypertension (2000) 14, 343-345

Adult↗
PubMed1999

Differential basal proenkephalin gene expression in dorsal striatum and nucleus accumbens, and vulnerability to morphine self-administration in Fischer 344 and Lewis rats.

We have previously shown that the acquisition rate of intravenous morphine self-administration under a fixed ratio one (FR1) schedule of reinforcement was greater in Lewis (LEW) than Fischer 344 (F344) rats. The purpose of the present experiment was to examine the relative motivational properties of morphine (1 mg/kg) or food under progressive ratio (PR) schedules of reinforcement in LEW and F344 rats. In addition, by using in situ hybridization histochemistry we have measured in both strains of rats the basal level of proenkephalin (PENK) gene expression in dorsal striatum and nucleus accumbens (NAcc). The results show that LEW rats responded to significantly higher breaking points (BPs) than F344 rats for intravenous morphine self-administration. In contrast, no differences were found in BPs for food pellets. Basal PENK mRNA levels were significantly higher in the dorsal striatum and nucleus accumbens of F344 than in LEW rats. Taken together, these results reveal a strain difference in the reinforcing efficacy of morphine and in the basal PENK gene expression in brain regions involved in the reinforcing actions of opiates. These data also suggest that the strain differences in opiate self-administration behavior found in this and other studies may be related, at least in part, to differences in basal opioid activity between LEW and F344 rats.

Animals↗
PubMed1999

The neurobiology of cannabinoid dependence: sex differences and potential interactions between cannabinoid and opioid systems.

Cannabis is the most widely used illicit drug in many western countries. Its psychoactive ingredient, delta9-tetrahydrocannabinol (THC), produces a variety of effects in animals and humans that are probably mediated by specific cannabinoid receptors in the brain and interactions with several neurotransmitter and neuromodulator systems. For instance, recent research has revealed an important mutual functional relationship between cannabinoids and endogenous opioid systems in mediating the pharmacological and behavioral actions produced by these agents, including their reinforcing effects. Perinatal exposure to and interactions between cannabinoids and opioids might also have long-term behavioral consequences lasting into adulthood. In this work, we present preliminary evidence examining the potential effects of maternal exposure to THC on the motivational properties of morphine in male and female adult rats, as measured by an intravenous opiate self-administration paradigm.

Animals↗
PubMed1999

Relationship of lipoprotein(a) levels to physical activity and family history of coronary heart disease.

OBJECTIVES: This study evaluated the association of physical activity with serum lipoprotein(a) [La(a)] levels in individuals according to whether they had a family history of coronary heart disease (CHD). METHODS: Lp(a) levels in 332 healthy Spanish men aged 20 to 60 years were measured. Physical activity and family history of CHD were assessed. RESULTS: For men with a family history of CHD, the odds ratio for Lp(a) levels above the median value was 0.13 (95% confidence interval = 0.03, 0.50) in very active men (energy expended in physical activity > 300 kcal/day) compared with active men (energy expended in physical activity < 300 kcal/day). CONCLUSIONS: Regular daily physical activity in individuals with a family history of CHD could be useful for controlling Lp(a) levels.

Adult↗
PubMed1998

Maternal exposure to delta9-tetrahydrocannabinol facilitates morphine self-administration behavior and changes regional binding to central mu opioid receptors in adult offspring female rats.

Opiates and cannabinoids are among the most widely consumed habit-forming drugs in humans. Several studies have demonstrated the existence of interactions between both kind of drugs in a variety of effects and experimental models. The present study has been focused to determine whether perinatal delta9-tetrahydrocannabinol (Delta9-THC) exposure affects the susceptibility to reinforcing effects of morphine in adulthood and whether these potential changes were accompanied by variations in mu opioid receptor binding in brain regions related to drug reinforcement. Adult female rats born from mothers that were daily treated with delta9-THC during gestation and lactation periods, exhibited a statistically significant increase in the rate of acquisition of intravenous morphine self-administration behavior when compared with females born from vehicle-exposed mothers, an effect that did not exist in delta9-THC-exposed male offspring. This increase was significantly greater on the last day of acquisition period. There were not significant differences when the subjects were lever pressing for food. In parallel, we have also examined the density of mu opioid receptors in the brain of adult male and female offspring that were exposed to Delta9-THC during the perinatal period. Collectively, perinatal exposure to delta9-THC produced changes in mu opioid receptor binding that differed regionally and that were mostly different as a function of sex. Thus, delta9-THC-exposed males exhibited a lower density for these receptors than their respective oil-exposed controls in the caudate-putamen area as well as in the amygdala (posteromedial cortical nucleus). On the contrary, delta9-THC-exposed females exhibited higher density of these receptors than their respective oil-exposed controls in the prefrontal cortex, the hippocampus (CA3 area), the amygdala (posteromedial cortical nucleus), the ventral tegmental area and the periaqueductal grey matter, whereas the binding was lower than control females only in the lateral amygdala. These results support the notion that perinatal delta9-THC exposure alters the susceptibility to morphine reinforcing effects in adult female offspring, in parallel with changes in mu opioid receptor binding in several brain regions.

Analgesics, Opioid↗
PubMed1998

Diagnostic imaging of lipoma arborescens.

OBJECTIVE: The imaging characteristics of lipoma arborescens using plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) are described. DESIGN AND PATIENTS: Five patients with a diagnosis of lipoma arborescens are presented. Three had monoarticular involvement of the knee joint. In the remaining two patients both knees and both hips, respectively, were affected. All patients were examined using plain radiographs and MRI. CT was employed in two cases. RESULTS AND CONCLUSIONS: A conclusive diagnosis with exclusion of other synovial pathologies having similar clinical and radiological behavior can be achieved on the basis of the MRI characteristics of lipoma arborescens. The aetiology of lipoma arborescens remains unknown, but its association with previous pathology of the affected joints in all our patients supports the theory of a non-neoplastic reactive process involving the synovial membrane.

Adult↗
PubMed1998

Differential expression of double-band apolipoprotein(a) phenotypes in healthy Spanish subjects detected by SDS-agarose immunoblotting.

A sodium dodecyl sulphate-agarose apolipoprotein(a) [apo(a)] phenotyping method was set up to attain accurate scanning densitometry of proteins. Serum samples from 99 healthy Spanish men were analysed and twenty-five different apo(a) isoforms (12 to 37 kringle 4 repeats) were detected. Double-band phenotypes accounted for 39.4% (n = 39) and three different patterns of protein expression were identified: pattern A (20.5% of double-band phenotyped samples) predominantly expressed the highest molecular weight isoform; pattern B (53.9%) mainly the lowest molecular weight isoform, and pattern AB (25.6%), expressed both isoforms equally. A significant linear association between expression pattern and lipoprotein(a) [Lp(a)] concentration > or = 0.30 g/l was observed. Single-band phenotyped samples (n = 60) were stratified according to apo(a) kringle 4 repeat categories and showed that 90% of isoforms < 20 K4 repeats had high Lp(a) concentrations (> or = 0.30 g/l), whereas isoforms with 20 to 24 or more than 24 kringle 4 repeats had Lp(a) concentrations > or = 0.30 g/l in 47% and 14%, respectively. A logistic regression model was fitted to test the association between apo(a) size, expression pattern and Lp(a) concentration. In this model, apo(a) isoform < 25 kringle 4 repeats was significantly associated with serum Lp(a) concentration > or = 0.30 g/l in both single and double-band phenotyped samples (odds ratio = 8.9, p < 0.001). In the latter, a differential expression pattern with respect to smaller size isoforms (pattern AB vs A) was significantly associated with Lp(a) concentration > or = 0.30 g/l (odds ratio = 17.97, P = 0.045). Heterogeneity in protein apo(a) size expressed according to kringle 4 repeat number could be categorized in heterozygous phenotypes as three patterns. When small-sized isoform was expressed (pattern B) or both isoforms were equally expressed (pattern AB), the probability of having Lp(a) > or = 0.30 g/l is higher.

Adult↗
PubMed1998

Chromosomal strategies for adaptation to univalency.

The orientation and segregation behaviour of different types of univalents, namely sex chromosomes, B chromosomes and autosomal univalents, were analysed in living spermatocytes of eight evolutionarily distant grasshopper species. The meiotic behaviour of each univalent was characterized in terms of velocity of prometaphase movements, frequency of reorientations, types of final orientation at metaphase I and modes of segregation at anaphase I. All these features were found to vary between different univalents. Certain combinations of these traits, defining a 'chromosomal strategy', appear commonly together in certain chromosome types, indicating that they are the result of selection acting on the chromosomes to increase transmission effectiveness. The sex univalents show in general a strategy in which all the features favouring an eventual equational segregation at anaphase I tend to be minimized. There is much more variation in behaviour among B chromosomes than among X chromosomes, which is a reflection of their heterogeneous nature. Induced autosomal univalents are studied in Locusta migratoria. They show a very irregular behaviour, indicating their lack of adaptation to univalency.

Anaphase↗
PubMed1998

[Multiple sclerosis in childhood: our experience and a review of literature].

INTRODUCTION: Multiple sclerosis (MS) is infrequent in childhood (0.3-2% of all cases of MS). At the present time more and more paediatric patients are being described. In this paper we describe our experience. MATERIAL AND METHODS: We review seven patients diagnosed as having MS before the age of 16, between 1984 and 1996. We have recorded: age, sex, personal and family history, form of onset and clinical course. CSF, neurophysiological and neuroimaging tests, treatment and diagnostic category according to the criteria of Poser. RESULTS: Four boys and three girls aged between three and thirteen years at the onset of the disorder. In one case there was a family history of MS. The most frequent form of onset was hemiparesia, followed by oculomotor paralysis and cerebellar disorders. Six cases followed a recurrent-remittent course and one followed a secondarily progressive course. There were oligoclonal bands (OGB) in the CSF in three cases. Visual evoked potentials (VEP) were abnormal in six cases. Magnetic resonance (RM) was a great help in diagnosis and in six cases was very informative. Six patients were treated with corticosteroids during the acute phase and two with long-term azathioprine. CONCLUSION: The commonest form of presentation, hemiparesia, makes the differential diagnosis with acute hemiplegia of childhood obligatory. Neurophysiological techniques, especially the VEP are very useful for initial assessment. RM is the most sensitive method, although it is not specific for diagnosis. The average follow-up period (4.5 years) is too short to determine the prognosis.

Adolescent↗
PubMed1997

Interaction of family history of atherosclerosis with atherogenic lipid traits in men with non-coronary atherosclerosis.

Family history of atherosclerosis has been recognised as an nonmodifiable cardiovascular risk factor. Lipid levels, together with hypertension and diabetes, appear to have an inheritable component. The aim of the study was to ascertain whether lipoprotein abnormalities of 169 adult patients with non-coronary atherosclerosis were associated with a family history of atherosclerosis. Besides intermediate density lipopoprotein composition and Lp(a) levels, we focused on apo(a) and apo E phenotypes, LDL cholesterol/apo B ratio, VLDL triglyceride/HDL cholesterol ratio, and environmental factors. We found that patients with a family history of atherosclerosis had a higher prevalence of VLDL triglyceride/HDL cholesterol ratio above 1.8 (51.3% vs 34.7%) than patients without. Similarly, there was a significant inverse correlation between both considered ratios (r = -0.24, p < 0.05). The odds ratio of the presence of both abnormal ratios (4.60, 95% CI, 1.41-15.00) and low molecular weight apo(a) isoforms (3.30, 95% CI, 1.05-10.30 and family history of atherosclerosis was independent of smoking and hypertension. Apo(a) isoform size seems to be more important than Lp(a) concentrations in the family history of atherosclerosis risk determination. Subsequent analysis showed that patients with a family history of atherosclerosis had a greater-than-fourfold increased risk of having one or both abnormal ratios reflecting metabolic disturbances which probably constitute a combined trait. Family history of atherosclerosis may constitute a specific lipoprotein-related marker of atherosclerosis. Such a marker often precedes the onset of overt disease and may contribute to identifying patients with an atherogenic lipoprotein profile even in the absence of classical lipid risk factors.

Adult↗
PubMed1997

A computer program based on parallel line assay for analysis of skin tests.

A computer program for the analysis of differences or changes in skin sensitivity has been developed. It is based on parallel line assay, and its main features are its ability to conduct a validation process which ensures that the data from skin tests conform to the conditions imposed by the analysis which is carried out (regression, parallelism, etc.), the estimation of the difference or change in skin sensitivity, and the determination of the 95% and 99% confidence intervals of this estimation. This program is capable of managing data from independent groups, as well as paired data, and it may be applied to the comparison of allergen extracts, with the aim of determining their biologic activity, as well as to the analysis of changes in skin sensitivity appearing as a consequence of treatment such as immunotherapy.

Analysis of Variance↗
PubMed1996

Effects of nimodipine and nifedipine upon behavior and regional brain monoamines in the rat.

The effects of single and repeated (9 times) administration of two dihydropyridines (DHPs), nimodipine (NIM) and nifedipine (NIF) (5 mg/kg per 12 h and 2.5 mg/kg per 12 h, IP), on the behavior of male adult rats in the holeboard and in the plus-maze, were investigated. Besides, the effects of repeated administration of the drugs on the levels of dopamine (DA), serotonin (5-HT), and their respective major metabolites in several regions of the central nervous system (CNS) were also assessed. The effects of single and repeated administration of the drugs were similar. Both DHPs caused a significant decrease in general motor activity which was evident in both tests and more marked, with the higher doses. The two exploratory parameters measured in the holeboard, i.e. head-dipping frequency and duration, were dissociated under pharmacological treatment. The drug-treated animals did not show an increased emotionality in the holeboard. However, in the plus-maze, NIF (5 mg/kg) and to a lesser extent NIM, appeared to induce some anxiety-related responses which may be secondary, at least in part, to the depressing effect on activity and exploration. Repeated administration of NIM and NIF caused an increase in striatal DA and DOPAC levels, whilst no effects were found on serotonergic system in any of the regions of the CNS analyzed.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1996

Sex-related pharmacokinetic and pharmacodynamic variations of lisinopril.

The aim of the present study was to determine whether or not the pharmacokinetic and hemodynamic response to a 20 mg single oral dose of lisinopril was sex-dependent. Thirty-two young healthy volunteers (16 males and 16 females) were included in the trial. Blood samples to assess lisinopril plasma concentrations, determined indirectly by inhibition of the angiotensin converting enzyme (ACE) and hemodynamic variables, were obtained before and at different times following drug intake. No significant differences in pharmacokinetic parameters were observed between males and females. An hypotensive response was obtained between 2 and 10 h for systolic blood pressure and between 2 and 24 h for diastolic blood pressure. Again, no significant sex-related differences were noted. Lisinopril was well tolerated.

Administration, Oral↗
PubMed1995

Bioavailability and pharmacokinetics of a new low molecular weight heparin (RO-11)--a three way cross-over study in healthy volunteers.

This study reports on the bioavailability and pharmaco kinetics of a new low molecular weight heparin (RO-11), with a mean molecular weight of 3,600-3,800 daltons. It was administered to 12 healthy individuals in an open, cross-over study. Each subject was randomly assigned to three experimental treatments: a) 30 mg by subcutaneous route, b) 60 mg subcutaneously and c) 60 mg intravenously, leaving a wash-out period of one week between treatments. The pharmacokinetic profile was calculated by means of the anti-FXa effect, measured on serial samples taken before and during the 24 h period after each treatment. The effects of the drug on global coagulation tests, Antithrombin-III levels, tissue-factor pathway inhibitor activity and anti-FIIa activity were also assessed. After the intravenous injection, a maximal anti-FXa effect of 1.30 +/- 0.18 IU/ml was measured at 0.05 h and was not measurable after 12 h. After the subcutaneous injection of 30 and 60 mg, the maximal anti-FXa effect (0.34 +/- 0.08 IU/ml and 0.54 +/- 0.06 IU/ml) was reached after 2-4 h, and was not measurable after 12-18 h. The magnitude of this effect was dose-dependent and the absorption and elimination processes followed a first-order pattern for every dose and route. RO-11 showed a biological half-life of about 5 h and a high subcutaneous bioavailability (96%).

Adult↗