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Biomedical subjects

A González

Publications and source records attributed to A González.

At least 19 recordsLinked to original sources
PubMed1995

Development of catecholamine systems in the central nervous system of the newt Pleurodeles waltlii as revealed by tyrosine hydroxylase immunohistochemistry.

The aim of the present study was to extend our knowledge of the development of catecholamine (CA) systems in the class of amphibians to the order of urodeles. In contrast to previous studies of urodeles, the present study with antisera against tyrosine hydroxylase (TH) and dopamine revealed that CA systems are already present at early embryonic stages of the newt, Pleurodeles waltlii. Although the development from fertilized egg to juvenile in the urodele Pleurodeles lasts twice as long as that in the anuran, Xenopus laevis, and shows less dramatic changes in external morphology, the spatiotemporal sequence of appearance of TH-immunoreactive cell groups is rather similar. An early appearance of TH-immunoreactive cell bodies occurs in the olfactory bulb, the posterior tubercle, the accompanying cell group of the hypothalamic periventricular organ, the suprachiasmatic nucleus, the locus coeruleus, an area immediately ventral to the central canal of the spinal cord, and in the retina. Somewhat later, immunoreactive cells are detected in the posterior thalamic nucleus and in the rostral portion of the midbrain tegmentum, whereas the preoptic cell group is the last one to become TH immunoreactive. The presence of CA systems at early embryonic stages of both anurans and urodeles suggests that these systems are already of functional significance early in development. The maturation of CA neuronal structures in the olfactory and retinal circuitries, which takes place during development earlier in amphibians than in mammals, supports that notion.

Animals↗
PubMed1995

Properties and roles of an intramembranous charge mobilized at high voltages in frog skeletal muscle.

1. Membrane Ca2+ currents (ICa), intramembranous charge movement currents and changes in intracellular Ca2+ concentrations were recorded in voltage clamped cut skeletal muscle fibres of the frog. Intra- and extracellular solutions, designed to prevent ionic current, and use of the saponin-permeabilization procedure made possible the measurement of transfer of intramembranous charge up to high positive potentials. 2. Substantial charge moved at positive potentials. This charge was shown to be intramembranous in four tests of charge conservation, demonstrating that the total displacement of charge depended only on the initial and final voltages, and not on the history or pathway of intermediate voltages. 3. On average, in twenty-three cells, the charge moved at 50 mV was 31 +/- 1.9 nC microF-1 (mean +/- S.E.M.), and at 0 mV was 25 +/- 1.5 nC microF-1. Approximately one-fifth of the total charge moved above 0 mV. 4. The charge that moved at high voltage could be fitted, in most cases, with a Boltzmann distribution function. In twenty of twenty-three cells, the total charge distribution could be fitted as the sum of two Boltzmann terms; the high voltage term was centred at 11 +/- 3.9 mV, with a steepness factor of 12 +/- 1.6 mV and a magnitude of 8.6 +/- 1.1 nC microF-1. The low voltage term was centered at -43 +/- 2.1 mV, with a steepness factor of 7.7 +/- 0.6 mV and a magnitude of 22 +/- 1.8 nC microF-1. Thus, the high voltage component comprised about one-quarter of the mobile charge. In four cells it was possible to fit the sum of three Boltzmann terms to the distribution of mobile charge; the parameters of the high voltage term then were similar to those found by fitting the sum of two Boltzmann terms to the same data. 5. The voltage dependence of activation of ICa was determined in a buffered 2 mM Ca2+ external solution, from the tails of ionic current at -30 mV, after activating pulses to various voltages, the duration of which was sufficient to reach the peak of inward current. The voltage dependence was described by a Boltzmann function centred at 2.6 +/- 6.9 mV (n = 6), with a steepness factor of 20 +/- 1.4 mV. The voltages at which the high voltage charge moved were roughly the same as those at which ICa was activated. 6. Calcium release from the sarcoplasmic reticulum was determined from the Ca2+ transients. Calcium release continued to increase at potentials above 0 mV.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

[Espartosis. A new type of extrinsic allergic alveolitis among construction plasterers].

The clinical characteristics of three plasterers in contact with esparto and who presented a picture of extrinsic allergic alveolitis which was peculiar because of their being hyperacute and causing hypoxemia. In addition to a review of 5 previously published sporadic cases the clinical picture of this new type of apparently infrequent alveolitis is described. The causal antigen is unknown although contamination by fungus or the addition of raw esparto may be the origin of the disease. After a review of the literature regarding this subject, the authors suggest that, in addition to cases of asthma and chronic airway obstruction, the patients with extrinsic allergic alveolitis be included under the name of espartosis following esparto dust inhalation.

Adult↗
PubMed1995

Secretion by Trypanosoma cruzi of a peptidyl-prolyl cis-trans isomerase involved in cell infection.

Macrophage infectivity potentiators are membrane proteins described as virulence factors in bacterial intracellular parasites, such as Legionella and Chlamydia. These factors share amino acid homology to eukaryotic peptidyl-prolyl cis-trans isomerases that are inhibited by FK506, an inhibitor of signal transduction in mammalian cells with potent immunosuppressor activity. We report here the characterization of a protein released into the culture medium by the infective stage of the protozoan intracellular parasite Trypanosoma cruzi. The protein possesses a peptidyl-prolyl cis-trans isomerase activity that is inhibited by FK506 and its non-immunosuppressing derivative L-685,818. The corresponding gene presents sequence homology with bacterial macrophage infectivity potentiators. The addition of the protein, produced heterologously in Escherichia coli, to cultures of trypomastigotes and simian epithelial or HeLa cells enhances invasion of the mammalian cells by the parasites. Antibodies raised in mice against the T.cruzi isomerase greatly reduce infectivity. A similar reduction of infectivity is obtained by addition to the cultures of FK506 and L-685,818. We concluded that the T.cruzi isomerase is involved in cell invasion.

Amino Acid Isomerases↗
PubMed1995

Evidence for a mesolimbic pathway in anuran amphibians: a combined tract-tracing/immunohistochemical study.

The aim of the present study was to determine whether a dopaminergic mesolimbic pathway, as found in the brain of amniotes, also exists in anuran amphibians. For that purpose, application of retrograde tracers in the nucleus accumbens of Rana perezi was combined with tyrosine hydroxylase immunohistochemistry. Double labeled cells were found in the dorsomedial part of the posterior tubercle and, more frequently, in the midbrain tegmentum. It may be concluded, therefore, that a dopaminergic mesolimbic pathway does exist in amphibians. Nevertheless, the organization of the ventral (mesolimbic) and dorsal parts of the mesostriatal connections seems to vary from a caudal-to-rostral arrangement in amphibians to a medial-to-lateral arrangement in amniotes.

Animals↗
PubMed1995

[Immunogenicity and safety of a tetanus-diphtheria vaccine (adult type): clinical trial in adults].

BACKGROUND: The administration of tetanus-diphtheria vaccine (Td, "adult" type) as booster dose every ten years, instead of tetanus toxoid, is a usual practice in the U.S., and its is being envisaged by the Spanish health authorities. In the present trial, the immunogenic capacity and the safety profile of the administration of one dose of Td vaccine to healthy adults, previously immunized to tetanus and diphtheria, was evaluated. METHODS: Healthy adults, who received one i.m. (deltoid) dose of Td vaccine containing 1.5 Lf and 10 Lf of adsorbed diphtheria and tetanus toxoids, respectively, participated in the study. Just before vaccination (baseline), and 4 weeks later, tetanus and diphtheria antibodies titres were determined by Elisa. The cut-off of these tests is 0.1 IU/ml. In this study, antitoxin titres > or = 0.1 IU/ml were considered as protective. Titres < 0.1 IU/ml were arbitrarily given the value of 0.05 IU/ml. Participating subjects recorded during the 3 days post-vaccination any local and systemic adverse events. RESULTS: One hundred and thirty nine medical students and health care workers (age +/- SD: 26 +/- 6 years) participated in this trial. At baseline and 4 weeks, the seroprotective levels were 70% and 100% for tetanus, and 31% and 90% for diphtheria, respectively. The geometric mean titres for tetanus and diphtheria antibodies at baseline and 4 weeks were: 0.59 and 8.54 IU/ml and 0.09 and 1.63 IU/ml, respectively. 82% of the subjects recorded some kind of adverse events, most of them local and mild. 66% referred local pain 24 h after the administration of the vaccine. Only 12% reported any kind of systemic adverse event: malaise (5%) and headache (4%) were the most commonly reported. All the adverse events were transient and did not require any medical attention or therapy. CONCLUSIONS: The Td vaccine tested in this study, when administered as booster dose to previously immunized adults, is highly immunogenic and shows an acceptable safety profile.

Adult↗
PubMed1995

Efficacy of screening donors for antibodies to the hepatitis C virus to prevent transfusion-associated hepatitis: final report of a prospective trial.

Routine screening of blood donors for anti-hepatitis C virus (HCV) has been implemented in most developed countries. However, the independent efficacy of such screening has not been established in a controlled, prospective study. We tracked 478 patients transfused with anti-HCV-negative blood by first-generation enzyme-linked immunoassay (EIA) between July 1989 and May 1990 and compared the incidence of transfusion-associated hepatitis and HCV infections with that found among 280 patients transfused with blood unscreened for anti-HCV during the immediately preceding year. Of the 280 patients who had received transfusions before donors were screened for anti-HCV, 27 (9.6%) developed posttransfusion hepatitis and 1 additional patient seroconverted to anti-HCV without evidence of hepatitis, for a risk of posttransfusion HCV infection of 10.7% (28 of 262 recipients seronegative for anti-HCV before transfusion). Of the 478 patients transfused after July 1989 with blood screened for anti-HCV, only 9 (1.9%) developed posttransfusion hepatitis for a risk reduction of 80%. Seven of the 9 residual cases of hepatitis were caused by HCV (7 of 456 recipients seronegative before transfusion or 1.5%) for a risk reduction of transfusion-associated HCV infection of 86%. In retrospect, an anti-HCV positive donor was detected by second-generation immunoassay in 4 (57%) of the 7 HCV cases from the study cohort and in 19 of the 23 (83%) cases from whom all donor samples were available for testing in the historical cohort. No additional infectious donors were detected by third-generation immunoassay or serum HCV-RNA by polymerase chain reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Does tetanus immune globulin interfere with the immune response to simultaneous administration of tetanus-diphtheria vaccine? A comparative clinical trial in adults.

In the management of wounds, sometimes it is recommended to give an adult-type tetanus-diphtheria (Td) vaccine dose plus tetanus immune globulin (TIG). Sixty and 59 healthy young adults previously immunized against tetanus (T) and diphtheria (D) were randomized to receive intramuscularly either Td vaccine alone (group 1) or Td vaccine plus 500 IU of TIG (group 2) simultaneously. Antitoxin response was assessed after 4 weeks and 4 months. Circulating antibodies were measured by enzyme-linked immunosorbent assay (ELISA). The cutoff of these tests was 0.1 IU/mL. Titers of 0.1 IU/mL or greater were considered protective. For geometric mean titers (GMT), antibody titers below the cutoff of the assay were given, arbitrarily, 0.05 IU/mL. At 4 weeks, 98% or more of the subjects in group 1 had circulating T and D antitoxin levels of 0.1 IU/mL or higher; in group 2, 95% and 90% of the subjects had titers above this limit for T and D, respectively. At 4 months, these percentages were 98% and 95% for T antitoxin levels in groups 1 and 2, respectively; whereas 96% and 88% of the subjects in groups 1 and 2 had D antitoxin levels of 0.1 IU/mL or higher, respectively. Significantly (P < .05) higher GMTs were seen at the 4-week assessment (but not at 4 months) in group 1, as compared with group 2, in both T and D antitoxin levels (9.91 IU/mL versus 5.60 IU/mL for T antitoxin, and 2.86 IU/mL versus 1.45 IU/mL for D antitoxin). This finding resulted from those participants with low (< 0.1 IU/mL) prevaccination antibody titers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Does continuous positive airway pressure (CPAP) during weaning from intermittent mandatory ventilation in very low birth weight infants have risks or benefits? A controlled trial.

OBJECTIVE: The purpose of this study was to evaluate three ventilator weaning strategies and to evaluate whether the use of continuous positive airway pressure (CPAP) via a nasopharyngeal or endotracheal tube would increase the likelihood of extubation failure in very low birth weight (VLBW) infants. STUDY DESIGN: We studied prospectively 87 preterm infants (mean +/- SD; birth weight: 1078 +/- 188 g; gestational age: 28.8 +/- 2.2 weeks) who were in the process of being weaned from intermittent mandatory ventilation (IMV). Infants were assigned by systematic sampling to one of the following three treatment groups: (1) direct extubation from IMV (D.EXT) (n = 30); (2) preextubation endotracheal CPAP (ET-CPAP) for 12-24 hr (n = 28); or (3) postextubation nasopharyngeal CPAP (NP-CPAP) for 12-24 hr (n = 29). Failure was defined as the need for resumption of mechanical ventilation within 72 hr of extubation due to frequent or severe apnea and/or respiratory failure (pH < 7.25, PaCO2 > 60 mm Hg, and/or requirement for oxygen FiO2 > 60%). RESULTS: There were no significant differences in failure rates among the three procedures. Failures were 2/30 (7%) in D.EXT; 4/28 (14%) in ET-CPAP; and 7/29 (24%) in the NP-CPAP. There were also no differences in FiO2, PaO2, and respiratory rates before and after discontinuation of IMV among the three groups. PaCO2 values were slightly higher in the NP-CPAP group 12-24 hr after weaning from IMV. CONCLUSION: We were unable to demonstrate a clear difference in extubation outcome by use of CPAP administered via an endotracheal or nasopharyngeal tube when compared to direct extubation from low-rate IMV in VLBW infants.

Airway Resistance↗
PubMed1995

Noradrenergic and adrenergic systems in the brain of the urodele amphibian, Pleurodeles waltlii, as revealed by immunohistochemical methods.

The distribution of noradrenaline and adrenaline in the brain of the urodele amphibian Pleurodeles waltlii has been studied with antibodies raised against noradrenaline and the enzymes dopamine-beta-hydroxylase and phenylethanolamine-N-methyltransferase. Noradrenaline-containing cell bodies were found in the anterior preoptic area, the hypothalamic nucleus of the periventricular organ, the locus coeruleus and in the solitary tract/area postrema complex at the level of the obex. Noradrenergic fibers are widely distributed throughout the brain innervating particularly the ventrolateral forebrain, the medial amygdala, the lateral part of the posterior tubercle, the parabrachial region and the ventrolateral rhombencephalic tegmentum. Putative adrenergic cell bodies were found immediately rostral to the obex, ventral to the solitary tract. Whereas the cell bodies and their dendrites were Golgi-like stained, axons were more difficult to trace. Nevertheless, some weakly immunoreactive fibers could be traced to the basal forebrain. A comparison of these results with data previously obtained in anurans reveals not only several general features, but also some remarkable species differences.

Animals↗
PubMed1995

Maximum a posteriori estimation of change points in the EEG.

A new approach for EEG segmentation is introduced. This is based on a methodology for optimal segmentation of non-stationary signals derived from the maximum a posteriori estimation principle. It is a model-based, not sequential approach that allows for segmentation at different resolution levels. The features of the methodology are illustrated by its application to EEG recordings containing several types of spectral changes due to normal and pathological variations of spontaneous brain rhythmic activities, as well as physiological artifacts.

Algorithms↗
PubMed1995

Compliance with immunization against hepatitis B. A pragmatic study in sexually transmitted disease clinics.

The efficacy of a vaccine is based primarily on the adherence of the subject to the immunization schedule. This paper compares the compliance rates (CR) for the third dose of hepatitis B virus (HBV) vaccine given according to one of two vaccination schedules among subjects attending two sexually transmitted disease (STD) clinics, and the potential influence of place of vaccine administration (STD clinic or at a vaccination centre). Heterosexual, anti-HBc seronegative subjects (n = 331) were randomized to a 0-1-6 month (n = 161) or a 0-1-2-12 month schedule (n = 170) in this prospective, randomized, parallel pragmatic study. Some subjects (n = 50) attended and were vaccinated at one STD clinic (centre A), whereas 281 attended another clinic (centre B) but were referred to a vaccination centre for administration of vaccine. About 31% (103/331) of the subjects received at least three vaccine doses. On assessing the CR at the 3rd dose in all randomized subjects, we observed that administration of the vaccine at the STD clinic attended (A) was associated with a significantly better CR (p < 0.01) than that of the subjects referred to a vaccination centre (B), while the CR is not affected by the schedule. On the other hand, the 0-1-2-12 schedule was associated with a significantly better CR (p = 0.02) at the 3rd dose than the 0-1-6 month schedule among subjects who comply with the first two doses; the actual site of vaccine administration (in situ (A) versus referred (B)) does not affect the CR.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

The trochlear nucleus of the frog Rana ridibunda: localization, morphology and ultrastructure of identified motoneurons.

The organization of the trochlear nucleus (N IV) was investigated in the frog Rana ridibunda. Retrograde tracing with horseradish peroxidase and biotinylated dextran amines resulted in labeling on the contralateral N IV of motoneurons with diverse morphologies and in direct caudal continuation with the oculomotor nucleus. Their dendritic arborizations extend profusely in the ipsilateral tegmentum and reach the oculomotor nucleus, the fasciculus longitudinalis medialis and also small processes branch towards the ventricle. Occasionally, one to three cells are labeled in the ipsilateral N IV, whereas mesencephalic trigeminal cells that would send their peripheral branch in the IVth nerve are never observed. The course of the labeled trochlear axons varies depending on the localization within the N IV of their cells of origin and different points of decussation are present above the midbrain ventricle. The ultrastructural analysis of identified trochlear motoneurons shows numerous axo-somatic synaptic contacts and six types of terminals with variable morphologies have been observed. Among them, a peculiar type of axon terminal forms mixed junctions with synaptic specializations and gap junctions together in the membrane interfaces that could represent the simultaneous presence of a chemical as well as an electrical component. The present data give more insights into the organization of the N IV and demonstrate that, although the organization of the trochlear nucleus is highly conservative in gnathostome vertebrates, it shows specific features for each species studied, as demonstrated for amphibians.

Animals↗
PubMed1995

A NADP-glutamate dehydrogenase mutant of the petit-negative yeast Kluyveromyces lactis uses the glutamine synthetase-glutamate synthase pathway for glutamate biosynthesis.

The activities of the enzymes involved in ammonium assimilation and glutamate biosynthesis were determined in wild-type and NADP-glutamate dehydrogenase (GDH) null mutant strains of Kluyveromyces lactis. The specific NADP-GDH activity from K. lactis was fivefold lower than that found in Saccharomyces cerevisiae. The glutamine synthetase (GS) and glutamate synthase (GOGAT) activities were similar to those reported in S. cerevisiae. The NADP-GDH null mutant was obtained by transforming the uraA strain MD2/1 with a linearized integrative yeast vector harbouring a 390 bp fragment of the NADP-GDH structural gene. This mutant grew as well as the parent strain on ammonium, but showed GS and GOGAT activities higher that those found in the wild-type strain, implying that the GS-GOGAT pathway could play a leading role in glutamate biosynthesis in K. lactis. Southern blotting analysis of K. lactis chromosomes separated by contour-clamped homogeneous electric field electrophoresis, indicated that the NADP-GDH structural gene is localized on chromosome VI.

Amino Acid Sequence↗
PubMed1995

A monoclonal antibody to swine erythrocytes recognizes the B blood group on the major glycophorin.

Recently monoclonal antibodies (mAbs) to swine red blood cells have been described. One of them (1AC11) was specific for the major swine glycoprotein with a molecular weight of 45 kDa and another mAb, 2G2, recognized the Ba allele in the B system of swine blood groups. Immunoblotting experiments to characterize the mAb 2G2 indicated that it reacts with an antigen of 45 kDa, present on the aqueous phase, glycophorin fraction, of swine red blood cells with the Ba allele and does not react with BbBb homozygous cells. The antigen recognized by 2G2 has the same characteristics as the major glycophorin recognized by 1AC11, so we can conclude that the B system of the swine blood group is on the major glycophorin of swine erythrocyte membranes.

ABO Blood-Group System↗
PubMed1995

Saccharomyces cerevisiae has a single glutamate synthase gene coding for a plant-like high-molecular-weight polypeptide.

Purification of the glutamate synthase (GOGAT) enzyme from Saccharomyces cerevisiae showed that it is an oligomeric enzyme composed of three identical 199-kDa subunits. The GOGAT structural gene was isolated by screening a yeast genomic library with a yeast PCR probe. This probe was obtained by amplification with degenerate oligonucleotides designed from conserved regions of known GOGAT genes. The derived amino-terminal sequence of the GOGAT gene was confirmed by direct amino-terminal sequence analysis of the purified protein of 199 kDa. Northern (RNA) analysis allowed the identification of an mRNA of about 7 or 8 kb. An internal fragment of the GOGAT gene was used to obtain null GOGAT mutants completely devoid of GOGAT activity. The results show that S. cerevisiae has a single NADH-GOGAT enzyme, consisting of three 199-kDa monomers, that differs from the one found in prokaryotic microorganisms but is similar to those found in other eukaryotic organisms such as alfalfa.

Amino Acid Sequence↗