Biomedical subjects

P Alvarez

Publications and source records attributed to P Alvarez.

At least 37 records · Page 2Linked to original sources

PubMed2000

[Three cases of imported dermatomycosis by Scytalidium dimidiatum].

Scytalidium dimidiatum dermatomycosis are usually reported in tropical and subtropical countries. Some cases in Spain have been diagnosed due to the increasing number of immigrants from these areas. We herein describe three new cases of S. dimidiatum infections detected in Madrid. Two patients were from Guinea Ecuatorial and the third from Angola. We also report the first case of S. dimidiatum infection in a HIV patient in Spain. Clinical and epidemiological characteristics of S. dimidiatum infections reported in Spain are discussed.

English Abstract↗

PubMed1999

Effect of hexachlorobenzene on NADPH-generating lipogenic enzymes and L-glycerol-3-phosphate dehydrogenase in brown adipose tissue.

The effect of the in vivo administration of hexachlorobenzene (HCB) (100 mg/100 g bw) for 30 days, on the activities of brown adipose tissue (BAT) lipogenic enzymes, i.e. malic enzyme (ME), and glucose-6-phosphate dehydrogenase (G6PD) and the mitochondrial non lipogenic enzyme, L-glycerol-3-phosphate dehydrogenase (LG3PD), was studied in male Wistar rats, submitted to various neurohormonal manipulations. BAT ME, G6PD and LG3PD activities showed significant reductions in response to HCB treatment both in euthyroid and surgically thyroidectomized rats, showing that the effect does not depend on the presence of thyroid hormones. These results differ from those obtained for hepatic ME and G6PD activities, which increased in HCB intoxicated rats without alteration in LG3PD. HCB decreased BAT ME activity under BAT denervation. Administration of HCB resulted in time and dose-dependent decreases in the activity of BAT malic enzyme. The basal activity of ME was increased in hypothyroid rats, while that of LG3PD was reduced. A stimulatory effect of receptor-saturating doses of triiodothyronine (T3) (50 microg/100 g body weight) was observed on BAT ME and LG3PD activities in thyroidectomized rats, showing that the enzymes responded to thyroid hormone stimulation in a normal manner. The stimulatory effect of saturating doses of T3 on ME and LG3PD was reduced by HCB. The results presented herein unequivocally show that brown adipose tissue is a specific target in HCB-induced toxicity, which in turn involves severe alterations in the regulation of BAT lipogenesis.

Adipose Tissue, Brown↗

PubMed1999

Crossmodal associative memory representations in rodent orbitofrontal cortex.

Firing patterns of neurons in the orbitofrontal cortex (OF) were analyzed in rats trained to perform a task that encouraged incidental associations between distinct odors and the places where their occurrence was detected. Many of the neurons fired differentially when the animals were at a particular location or sampled particular odors. Furthermore, a substantial fraction of the cells exhibited odor-specific firing patterns prior to odor presentation, when the animal arrived at a location associated with that odor. These findings suggest that neurons in the OF encode cross-modal associations between odors and locations within long-term memory.

Animals↗

PubMed1998

Cloning and sequence analysis of the Pichia pastoris TRP1, IPP1 and HIS3 genes.

The Pichia pastoris TRP1 and HIS3 genes were cloned by complementation of the Saccharomyces cerevisiae trip1 and his3 mutants, respectively, and their nucleotide sequence was determined. The P. pastoris TRP1 gene includes an open reading frame (ORF) of 714 nucleotides corresponding to a polypeptide of 237 amino acids whose sequence shares about 40% identity with that of TRP1 encoding proteins in other yeast species. DNA sequencing showed that an ORF of 858 nucleotides, encoding a protein of 285 amino acids with high homology to inorganic pyrophosphatases (IPP1), is located downstream of the P. pastoris TRP1 gene. Both genes converge in this chromosomal region, showing a genetic organization analogous to that found in the Kluyveromyces lactis genome. The P. pastoris HIS3 gene possesses an ORF of 675 nucleotides, encoding a polypeptide of 224 amino acids which shows 74.1% identity to the homologous S. cerevisiae protein. The hexameric consensus GCN4 binding sequence (TGACTC), characteristic of many amino acid biosynthetic genes, is present in the promoter region.

Aldose-Ketose Isomerases↗

PubMed1998

Modulation of tubulin polypeptide ratios by the yeast protein Pac10p.

Normal assembly and function of microtubules require maintenance of the proper levels of several proteins, including the tubulin polypeptides themselves. For example, in yeast a significant excess of beta-tubulin causes rapid microtubule disassembly and subsequent cell death. Even the modest excess of beta-tubulin produced by genetic alterations such as deletion of the minor alpha-tubulin gene TUB3 affects cell growth and can confer microtubule phenotypes. We show here that the levels of the yeast protein Pac10p affect the relative levels of the tubulin polypeptides. Cells deleted for PAC10 have the same phenotypes as do cells that express reduced levels of alpha-tubulin or Rbl2p, two proteins that bind beta-tubulin. Conversely, overexpression of Pac10p enhances the ability of alpha-tubulin or Rbl2p to suppress the lethality associated with excess beta-tubulin. However, Pac10p is itself not a beta-tubulin binding protein. Pac10 null cells show a 30% decrease in the ratio of alpha-tubulin to beta-tubulin. The results suggest that Pac10p modulates the level of alpha-tubulin in the cell, and so influences microtubule morphogenesis and tubulin metabolism.

Cloning, Molecular↗

PubMed1998

[Behavioral evaluation of the unilateral lesion model in rats using 6-hydroxydopamine. Correlation between the rotations induced by D-amphetamine, apomorphine and the manual dexterity test].

INTRODUCTION: Evaluation of rotatory activity induced by dopaminergic agonists is the most widely used test of conduct for the measurement of dopaminergic depletion of a unilateral lesion of the striatonigral pathway caused by 6-hydroxydopamine (6-OHDA) in rats, since it is quantitatively related to the extension of the dopaminergic denervation. OBJECTIVE: The objective of this study was to evaluate, from different angles, the changes in conduct seen in the model of unilateral lesion with 6-OHDA and to establish correlation with the rotation induced by D-amphetamine and by apomorphine and the ladder test. MATERIAL AND METHODS: Male Wistar rats were used. Lesions were produced in the SNpc by stereotactic injection of 6-OHDA into the right hemisphere and the effectiveness of the lesions was studied using the rotary conduct induced by D-amphetamine and apomorphine. The motor ability of the front legs was measured by the ladder test, carried out under standard and forced conditions. RESULTS: All the animals with lesions had difficulty in reaching food with both legs, although the most pronounced deficit was in the leg contralateral to the lesion. The ladder test correlated better with rotatory activity induced by apomorphine than by D-amphetamine. CONCLUSION: The animals with most dopamine loss showed most deficient use of their front legs.

Animals↗

PubMed1997

[Tuberculosis outbreak: significance of exposure time versus proximity to infection source].

BACKGROUND: The polymorphic length restriction fragment technique (PLRF) complements epidemiologic investigations. The aim of this study was to present an outbreak of tuberculosis in which the risk factors of infection and disease were studied. PATIENTS AND METHODS: A descriptive study was carried out in cases of tuberculosis. The isolated strains of Mycobacterium tuberculosis were typed by the PLRF technique. A study of the prevalence of infection was carried out among the 61 classmates of two classrooms (A and B) which the index case attended. An historical cohort study was thereafter performed among the cases with infection. The association of the dependent variable (infection or tuberculosis disease) with the remaining variables was determined by the odds ratio (OR). RESULTS: The incidence of disease was 9.8% (6/61). The strains isolated in 5 patients presented the same PLRF pattern. The prevalence study detected 28 infections (45.9%). Five cases (17.9%) were detected on the second tuberculin test. By multivariate analysis showed that the hours of exposure (1.8-3.2 hours, OR = 2.0; > 3.2 hours; OR = 10.2) were the risk factor for infection. The BCG vaccine, the intensity of the reaction to the tuberculin test and age could be associated with the risk of disease. CONCLUSIONS: The focus of the outbreak was confirmed by the PLRF technique. The importance of repeating the tuberculin test in whom the test was negative on the first test is of note. To evaluate the risk of infection the time of exposure is more important than the proximity to the index case.

Adolescent↗

PubMed1997

Regional distribution of specific high affinity binding sites for 3H-imipramine and 3H-paroxetine in human brain.

The binding of 3H-paroxetine and 3H-imipramine has been compared in 17 different regions of 12 human control brains. Our findings reveal that the regional distribution is similar for both radioligands and their bindings tend to be parallel in the brain. The highest binding site density was found in basal ganglia (hypothalamus Bmax 780 +/- 102 fmol/mg protein for 3H-imipramine binding and Bmax 515 approximately 83 for 3H-paroxetine binding). The lowest values were found in cortical areas (cingulate cortex 191 +/- 18.5 fmol/mg for 3H-imipramine binding and 88 +/- 7.5 fmol/mg for 3H-paroxetine binding). The Kd values for 3H-paroxetine binding to neuronal membranes were similar in all brain regions (mean +/- s.d. Kd 0.07 +/- 0.007 nM) and also for 3H-imipramine binding (mean +/- s.d. Kd 1.05 +/- 0.12 nM). As these values are the same as in platelet membrane, the results obtained indicate that both binding sites are identical in neuronal and in platelet membranes. These findings suggest that both ligands are good markers of the 5HT transporter. However, the higher affinity of 3H-paroxetine confirms that this compound is a better radioligand for the 5HT uptake site.

Adult↗

PubMed1997

High affinity [3H]imipramine and [3H]paroxetine binding sites in suicide brains.

Specific binding of [3H]imipramine and [3H]paroxetine was simultaneously examined in human brains (frontal cortex, temporal cortex, cingulate cortex, hypothalamus, hippocampus and amygdala) from 11 controls and 11 depressed suicide victims. A single saturable high affinity site was obtained for both radioligands. Age was not related to significant changes in [3H]imipramine and [3H]paroxetine binding parameters, which indicates the stability of the brain serotonergic system with increasing age. A major finding of the present study concerns the existence of a significant decrease in the maximum number (Bmax) of [3H]imipramine binding sites in hippocampus from depressed suicides as compared with the control group, without changes in the binding affinity (Kd). In contrast, when [3H]paroxetine was used as radioligand, no changes in either Bmax or Kd were detected in any of the brain regions studied. These findings suggest that [3H]imipramine may be a better marker than [3H]paroxetine when alterations in the presynaptic serotonergic uptake site are to be detected.

Adolescent↗

PubMed1997

Lesion of nigrostriatal neurons by 6-hydroxydopamine induces changes in rat brain glutathione-S-transferase.

Wistar rats were lesioned into the nigrostriatal pathway with 6-OHDA. The D-amphetamine-induced circling behavior test was performed to evaluated lesion efficiency. Animals that showed more than 620 turns/90 min were named totally lesioned animals (TLA). The group of rats that performed less than 620 turns/90 min were named partially lesioned animals (PLA). The contents of DA and its catabolites in the striata of these groups, and in the same tissue of the untreated animals, were measured. Moreover, the striatal glutathione-S-transferase (GST) specific activity for all groups was tested, and the kinetics parameters for GST purified from the whole brain were evaluated from other three similar groups. The striatal DA depletion on TLA was greater than in PLA. Striatal GST activity showed a significantly bilateral increase in PLA, whereas TLA exhibited only and ipsilateral augment. There were also differences between groups about the kinetic parameters of the purified brain enzyme. The possible role of GST on the interindividual lesion response difference was analyzed.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1997

Platelet [3H]imipramine and [3H]paroxetine binding in depressed patients.

[3H]Paroxetine and [3H]imipramine binding to blood platelet membranes was simultaneously measured in 63 control subjects and 18 patients with DSM-III-R criteria for major depression with melancholia. Both binding sites showed significantly different (p < 0.001) maximum binding (Bmax) and equilibrium dissociation constant (Kd) values. Age was not correlated with either [3H]imipramine Bmax or Kd values, but a negative correlation was found between [3H]paroxetine Bmax and age in healthy controls. Furthermore, depressed patients showed significantly lower [3H]imipramine Bmax values (p < 0.001) and higher Kd values (p < 0.001) in comparison to the control group. No differences were observed in [3H]paroxetine Bmax and Kd values between the two groups.

Adult↗

PubMed1997

Insulin-like growth factor-binding protein-2 and -3: their biological effects in bovine thecal cells.

This study was aimed at testing the hypothesis that the insulin-like growth factor-binding proteins (IGFBP)-2 and -3 can modulate the hormone-dependent differentiation of thecal cells in vitro. Thecal cells from large (> or = 8 mm) follicles were collected from cattle, cultured for 2 days in medium containing 10% fetal calf serum, washed, and then treated for an additional 2 days in serum-free medium with bovine LH (100 ng/ml), recombinant human insulin-like growth factor (IGF)-I (0 or 30 ng/ml), recombinant human IGFBP-2 (0, 200, or 400 ng/ml; i.e., 0, 6.5, or 12.9 nM), or recombinant human IGFBP-3 (0, 200, or 400 ng/ml; i.e., 0, 4.3, or 8.5 nM). IGFBP-2 (200 and 400 ng/ml) inhibited (p < 0.05) IGF-I-induced androstenedione production by 18-30% but did not influence (p > 0.10) progesterone production or thecal cell proliferation in the presence of LH and/or IGF-I. In contrast, IGFBP-3 (200 ng/ml) inhibited the IGF-I-induced increase in thecal cell numbers by 76%, and thecal cell progesterone and androstenedione production by 52% and 89%, respectively. A higher dose of IGF-I (i.e., 100 ng/ml) overcame the inhibitory effects of IGFBP-3 on IGF-I-induced cell proliferation and on progesterone and androstenedione production by thecal cells. As with IGFBP-2, IGFBP-3 had no effect (p > 0.10) on LH-induced progesterone or androstenedione production by thecal cells in the absence of IGF-I. Both IGFBP-2 and IGFBP-3 directly inhibited [125I]IGF-I and -II binding to thecal cells; IGFBP-2 was a weaker inhibitor of thecal [125I]IGF-I and -II binding than IGFBP-3. These results indicate that IGFBP-3 has a more pronounced inhibitory effect than IGFBP-2 on IGF-I action in cultured bovine thecal cells. Thus, IGFBP-3 may play a more significant role than IGFBP-2 in regulating thecal cell proliferation and steroidogenesis during follicular development in cattle.

Androstenedione↗

PubMed1996

The safety and effectiveness of stepwise and low-dose administration of follicle stimulating hormone in WHO group II anovulatory infertile women: evidence from a large multicenter study in Spain.

PURPOSE: Our goal was to investigate the safety, effectiveness, and feasibility for the practicing physician of stepwise and low-dose administration of FSH in WHO group II anovulatory infertile women. METHODS: Infertile female patients (n = 234) suffering from WHO group II anovulation, and who failed to became pregnant with clomiphene citrate, were included in a multicenter, prospective, clinical study of treatment with a protocol of chronic low-dose and small incremental rises with urinary purified or highly purified FSH. Follicular development was monitored with ultrasonographic scans. RESULTS: The 234 patients received a total of 534 cycles of treatment, for a mean number of 2.3 treated cycles per patient. hCG was withheld in 65 (12.2%) cyles because of no response and in 28 (5.2%) cycles because of hyperresponse. Of the remaining 441 cycles, 419 (95%) were ovulatory, and in 198 (47.3%) of these cycles a single dominant follicle developed. There were 93 pregnancies (39.7% per patient), for a cycle fecundity rate of 17.4%. Cumulative conception rate after two treated cycles was 33.5%. There were 14 (15%) pairs of twins and 10 (10.8%) spontaneous miscarriages. The prevalence of complications was low with no cases of severe OHSS. Basal LH/FSH ratio was significantly higher in the pregnant group of patients than in nonpregnant women. CONCLUSIONS: Stepwise and chronic low-dose administration of FSH is a safe and effective method for treatment of WHO group II anovulatory infertility, mainly in those patients having high LH/FSH ratios.

Adult↗

PubMed1995

Retrograde amnesia and memory consolidation: a neurobiological perspective.

The fact that information acquired before the onset of amnesia can be lost (retrograde amnesia) has fascinated psychologists, biologists, and clinicians for over 100 years. Studies of retrograde amnesia have led to the concept of memory consolidation, whereby medial temporal lobe structures direct the gradual establishment of memory representations in neocortex. Recent theoretical accounts have inspired a simple neural network model that produces behavior consistent with experimental data and makes these ideas about memory consolidation more concrete. Recent physiological and anatomical findings provide important information about how memory consolidation might actually occur.

Amnesia, Retrograde↗

PubMed1995

Zinc supplementation and growth of infants born small for gestational age.

To analyze the effect of zinc supplementation on postnatal growth of infants born small for gestational age, we selected 68 infants at birth and followed them monthly for 6 months. They were randomly assigned to a supplemented group (group S, n = 35) receiving 3 mg of Zn (acetate) per day, or to a placebo (group P, n = 33), in a double-blind study. Weight increments in group S were significantly higher than those in group P at 2 months (p < 0.003); z scores showed catch-up growth only in group S. Length increments were also greater in group S than in group P, ending at 6 months were 64.9 +/- 1.8 versus 63.4 +/- 3.5 cm (mean +/- SD; p < 0.01); changes in z scores for 6 months were -1.28 to -0.66 in group S and -1.43 to -1.47 in group P (p < 0.001). Weight-for-length improved similarly in both groups (z score, -2.2 to +0.2). The increase in weight-for-age was higher in group S girls (p < 0.034), ending at 6 months with -0.13 +/- 0.59, versus -0.52 +/- 0.62 in group S boys, -1.15 +/- 0.49 in group P girls, and -1.05 +/- 0.80 in group P boys (+/- SD). More infants in group P received cow milk-based formula before 4 months because of inadequate weight increments. An additive effect on weight increase was observed between Zn supplementation (p < 0.02), exclusive breast-feeding after 4 months of age (p < 0.001), and gender (p < 0.02). Plasma and hair Zn values showed a downward trend, less marked in group S than in group P. We conclude that Chilean infants born small for gestational age have better weight and linear growth during the first 6 months of life if they receive Zn supplementation.

Acetates↗

PubMed1995

Factors affecting variation of udder traits of dairy ewes.

Udder depth, width, and circumference; cistern height; teat position, angle, length, and width; and milk yield at 120 d were studied in 113 Churra sheep from three flocks. Means were 9.30, 12.18, and 46.55 cm, respectively, for udder depth, width, and circumference; 1.48 cm for cistern height; 3.64 (scored from 1 to 5) for teat position; 50.39 degrees for teat angle; 3.83 and 1.93 cm, respectively, for teat length and width; and 132.39 L for milk yield. Analysis of variance showed significant effects for lactation month, flock, parity number, and milk yield. The traits related to udder size (depth, width, and circumference) were significantly influenced by lactation month, flock, and milk yield and showed low repeatability (.17 to .18). The traits related to cistern morphology (cistern height, teat position, and angle) were significantly influenced by flock and parity number. These traits, together with teat length and width, had high repeatabilities (.45 to .77). Cistern height, teat position and angle, and size of teats are related to aptitude of the udder for mechanical milking. This association, as with cattle, would justify focusing genetic improvement on these traits.

Animals↗

PubMed1995

Damage limited to the hippocampal region produces long-lasting memory impairment in monkeys.

Research in humans and monkeys has demonstrated a system of anatomically related structures in the medial temporal lobe that is important for memory function. This system is comprised of the hippocampal region (i.e., the dentate gyrus, hippocampus proper and subicular complex) and the entorhinal, perirhinal, and parahippocampal cortices. While the hippocampal region has long been thought to be important in memory, there are few systematic studies in primates of the effects on memory of damage limited to the hippocampal region. We have used magnetic resonance imaging techniques, together with a stereotaxic approach, to produce bilateral lesions limited to the hippocampal region (the H lesion). Damage to the adjacent perirhinal, entorhinal, and parahippocampal cortex was minimal. Monkeys with the H lesion exhibited significant and long-lasting impairment on the delayed non-matching to sample task. At the same time, on this and other amnesia-sensitive tasks, monkeys with the H lesion performed better overall than monkeys with lesions of the hippocampal region that also included damage to the adjacent entorhinal and parahippocampal cortices (the H+ lesion). These findings show that, first, the hippocampal region itself is essential for normal memory function; and second, the adjacent entorhinal and parahippocampal cortices, either alone or in combination, are also an essential component of the medial temporal lobe memory system.

Animals↗

PubMed1994

A new system for the release of heterologous proteins from yeast based on mutant strains deficient in cell integrity.

A system has been developed for the release of heterologous proteins from Saccharomyces cerevisiae, based on the use of thermosensitive osmotic-remedial mutants, deficient in cell integrity, that lyse at the non-permissive temperature, thus releasing the bulk of intracellular proteins and leaving behind cell ghosts and debris. The strains developed combine the lyt2 mutation (which is allelic to gene SLT2/MPK1 coding for a MAP kinase homolog), with the disruption of genes PEP4 and PRB1 known to produce a protease-deficient background. Cells transformed with the appropriate bacterial gene, released about 70% of the heterologous protein chloramphenicol acetyl transferase (CAT) in bioreactor cultivation upon switching growth temperature to 37 degrees C, or by osmotic shock of the cells preincubated at 37 degrees C in the presence of 1 M sorbitol. It is suggested that our release system could be advantageous for obtaining large-scale protein preparations for downstream processing without any mechanical breakage of the cells, enzymatic treatment or chemical extraction.

Chloramphenicol O-Acetyltransferase↗