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Biomedical subjects

A Ortega

Publications and source records attributed to A Ortega.

At least 19 recordsLinked to original sources
PubMed1997

NMDA receptors in cultured radial glia.

The expression of the NMDA subtype of glutamate receptors was investigated by Western blot analysis and RT-PCR in cultured chick Bergmann and Müller glial cells. Using subunit-specific antibodies directed to the carboxy terminus of the rat NMDAR2A/B we detected the expression of the NMDAR2 subunit in both kinds of culture. The functional subunit of the NMDA receptor, NMDAR1, was detected by means of RT-PCR. These results, together with our previous functional characterization of NMDA receptors in radial glia, provide conclusive evidence for the expression of functional NMDA receptor/channels in Bergmann and Muller glia cells. Our findings strengthen the notion of a modulatory role of glial cells in synaptic transmission.

Animals↗
PubMed1997

Modulation of immune cell populations and activation markers in the pathogenesis of African swine fever virus infection.

African swine fever (ASF) virus induces immune cell alterations that may be detected by changes in peripheral blood cells phenotypic antigens and activation markers which were examined by flow cytometry, analyzing both cell proportion and/or expression intensity of superficial antigens. These studies were conducted in pigs with experimental acute of chronic ASF infection to determine whether changes among important surface activation markers and phenotypic antigens, and their correlative lymph node status, reflected similar or disparate aspects of immune pathology. In acute infection produced by virulent viruses, macrophage and B lymphocyte populations decreased in peripheral blood after a short activation period at the beginning of the infection. A significative decrease of interleukin 2 receptor (IL 2R) expression was also observed in those pigs. These variations correlated with lymph node cell depletion due to an intense lymphoid cell death by apoptosis, affecting mainly the B lymphocyte subpopulation as determined by immunohistochemistry. Nevertheless, pigs infected with an attenuated isolate undergoing chronic persistent infection, presented a distinct pattern of modification, according with a different clinicopathological evolution. Changes consisted in systemic immune activation coincident with the highest viremia titer, with an augmentation in CD8+ T lymphocyte, macrophage, and B cell populations, and MHC (major histocompatibility complex) antigens. Percentage elevation of circulating immune subpopulations was accompanied by cell accumulation with lymphoid hyperplasia but a conserved distribution of B lymphocytes in lymphoid organs of chronically infected pigs.

Acute Disease↗
PubMed1997

Excitatory amino acid receptors coupled to the phosphoinositide pathway in Bergmann glia.

Glutamate (L-glu) receptors coupled to phosphoinositide hydrolysis in primary cultures of Bergmann cells from chick cerebellum were characterized biochemically and pharmacologically. Both ionotropic and metabotropic receptor agonists stimulated [3H] inositol phosphates accumulation in the following order of potency: QA > NMDA > L-glu > KA approximately QA > AMPA > > t-ACPD. QA showed a biphasic dose-response curve (EC50 = 0.07 and 53 microM), suggesting interaction with two populations of receptors; L-glu was the most efficient agonist. Stimulation by NMDA was blocked by CPP, AP5 and MK-801; that by AMPA and KA was inhibited 100% by CNQX and DNQX, whereas the effect of QA was decreased both by CNQX and the metabotropic antagonist 4-CPG. Stimulation of PIP2 hydrolysis induced by metabotropic L-glu receptor agonist t-ACPD was blocked by 4-CPG but was only moderately inhibited by MCPG. EAA-induced [3H]IPs accumulation was dependent on external Ca2+ and was not affected by nifedipine verapamil, or dantrolene; thapsigargin increased the effect. Results suggest that EAA activate the PI pathway in Bergmann glia through ionotropic (NMDA and AMPA/KA) as well as metabotropic receptor subtypes (t-ACPD) which could act jointly influencing neurotransmission at the parallel fiber-Purkinje cell synapses in the cerebellum.

Animals↗
PubMed1997

Genotypic assessment of isoniazid and rifampin resistance in Mycobacterium tuberculosis: a blind study at reference laboratory level.

Progress in understanding the basis of resistance to isoniazid (INH) and rifampin (RMP) has allowed molecular tests for the detection of drug-resistant tuberculosis to be developed. Consecutive isolates (n = 95) of Mycobacterium tuberculosis, from a Spanish reference laboratory investigating outbreaks of multidrug-resistant tuberculosis, were coded and sent to two external laboratories for genotypic analysis of INH and RMP resistance by PCR-single-strand conformation polymorphism (SSCP) analysis of specific regions of four genes: part of the coding sequence of katG and the promoter regions of inhA and ahpC for INH and the RMP resistance region of rpoB. After correction for the presence of outbreak strains and multiple isolates from single patients, RMP resistance was detected successfully by PCR-SSCP in > 96% of the RMP-resistant strains. PCR-SSCP had a sensitivity of 87% for INH resistance detection, and mutations in katG, inhA, katG-inhA, ahpC, and katG-ahpC were identified in 36.8, 31.6, 2.6, 13.2, and 2.6%, respectively, of the unique strains. Specificity was 100%. Molecular detection of resistance to the two main antituberculous drugs, INH and RMP, can be accomplished accurately by using a strategy which limits analysis to four genetic regions. This may allow the expedient analysis of drug resistance by reference laboratories.

Antibiotics, Antitubercular↗
PubMed1997

Impact of the human immunodeficiency virus epidemic on detection of Mycobacterium isolates in a general hospital.

The number of human samples processed in our mycobacteriology laboratory ranged from 148 per 1,000 admissions in 1988 to 263 per 1,000 admissions in 1995 (5.2% were positive). The human immunodeficiency virus (HIV)-positive population contributed 33.3% of all samples, 43.3% of all isolates, and 36% of all new patients. Given that the ratios of the total number of samples to the number of Mycobacterium-positive samples were 18.3:1 in HIV-positive patients and 28:1 in HIV-negative patients, efforts to reduce the laboratory workload should begin with the HIV-negative population.

Disease Outbreaks↗
PubMed1997

Effect of the organic Ca2+ channel blocker D-600 on sarcoplasmic reticulum Ca2+ uptake in skeletal muscle.

Experiments were undertaken to study the possibility that the calcium channel blocker D-600 (gallopamil), which penetrates into muscle cells (20), facilitates excitation-contraction coupling in skeletal muscle (7) by a direct effect on the sarcoplasmic reticulum (SR). The effects of D-600 were studied on single phasic muscle fibers, either intact or split open. D-600 potentiated twitches in intact fibers at concentrations lower than those reported in whole muscles. In split fibers, the force produced by caffeine-induced Ca2+ release from the SR was reversibly inhibited by 5 microM D-600, when added to the Ca2+ loading solution. This inhibitory effect was inversely related to temperature, and it was dose dependent. When D-600 was added after Ca2+ loading and before caffeine exposure, or during the caffeine exposure itself, it did not inhibit Ca2+ release, but rather increased the development of force. We conclude that, apart from the blocking effect that D-600 may have on the voltage sensor, the drug penetrates into the myoplasm and affects excitation-contraction coupling by inhibiting the SR Ca2+ pump. This may be the consequence of a conformational change in the transmembrane Ca2+ binding domain of the ATPase.

Animals↗
PubMed1997

A longitudinal study of transmission of tuberculosis in a large prison population.

The purpose of this study was to determine the extent of transmission of tuberculosis in a large prison population over an 18-mo period. Restriction-fragment-length polymorphism (RFLP) analysis of isolates of Mycobacterium tuberculosis was performed, using the insertion sequence IS6110 and the plasmid pTBN12. Patients infected with strains having the same fingerprint were grouped in clusters. Medical records were reviewed and movement of inmates among prisons was examined for selected patients. Tuberculosis was diagnosed in 216 inmates (case rate = 2,283 per 100,000 per year). Isolates from 210 (97%) patients were fingerprinted, 155 (74%) were grouped in 25 clusters, and 55 (26%) showed a unique fingerprint. Recent infection was inferred in 62% of these patients. Eighty-four percent (161 of 192) of patients tested were human immunodeficiency virus (HIV)-positive, of whom 121 were in clusters and 40 were not (p = 0.74). Patients in clusters were less adherent with tuberculosis treatment than those not in clusters (p < 0.05), and prison transmission of resistant strains was observed. It is crucial that infection control guidelines be fully implemented in the prison setting to prevent tuberculosis transmission.

Adult↗
PubMed1996

Cholesterol increases the thermal stability of the Ca2+/Mg(2+)-ATPase of cardiac microsomes.

The effect of membrane cholesterol on the thermal inactivation of Ca2+/Mg(2+)-ATPase activity of bovine cardiac microsome was measured and compared to the thermal denaturation profiles of the microsomes as measured by differential scanning calorimetry (DSC). Inactivation, defined as loss of activity, and denaturation, defined as conformational unfolding, were irreversible under the conditions used. Both thermal inactivation of Ca2+/Mg(2+)-ATPase activity and thermal denaturation were shifted to higher temperatures in microsomes enriched with cholesterol (37 +/- 5 micrograms cholesterol/mg protein, cholesterol/phospholipid molar ratio 0.31) compared to control microsomes (15 +/- 3 micrograms cholesterol/mg protein, molar ratio 0.12). Thermal inactivation was measured by two methods: first, measuring activity at room temperature as a function of heating to elevated temperatures at 1 K/min, where inactivation temperatures (T1, temperature of half activity) were 58.9 +/- 0.3 degrees C for control membranes and 59.9 +/- 0.1 degrees C for cholesterol-enriched membranes, respectively. Second, measuring ATPase activity as a function of time at constant temperature, where T1 values of 57.6 +/- 0.5 degrees C and 59.2 +/- 0.5 degrees C were determined for control and cholesterol-enriched membranes, respectively. DSC profiles of microsomal membranes consisting of a number of overlapping peaks were obtained. A well resolved component (transition C) was observed with a transition temperature (T 1/2) of 58.2 degrees C. This T 1/2, which is a measure of conformational stability, correlates with the T1 for Ca2+/Mg(2+)-ATPase activity and is 1.9 +/- 0.6 K higher in cholesterol-enriched membranes. Thus, the increased resistance to inactivation appears to be due to increased conformational stability of the protein induced by cholesterol, demonstrating that a change in lipid composition can influence the stability of an integral membrane protein in a natural membrane. The increased stability is of sufficient magnitude to account for the previously observed correlation between cholesterol content and resistance to heat shock in several cell lines.

Animals↗
PubMed1996

Membrane healing and restoration of contractility after mechanical injury in isolated skeletal muscle fibers of the frog.

In single isolated skeletal muscle fibers of the frog, we studied (i) the recovery from large sarcolemmal mechanical injuries of the response to electric stimulation and (ii) the integrity of the sarcolemma under the light microscope. In Ringer's solution, the damaged cells stopped contracting and deteriorated completely within 1 hr. In the presence of phosphatidylcholine (0.025 g/ml in Ringer's solution), the injured cells initially responded with local twitches. Within 0.5 hr, contractility and membrane integrity started to recover and both were back to control levels within 3 hr. When these cells were placed back in normal Ringer's solution, they remained viable and active for several hours. Our results suggest that phosphatidylcholine can protect muscle fibers from the effects of sarcolemmal injury.

Animals↗
PubMed1996

Entamoeba histolytica: involvement of pp125FAK in collagen-induced signal transduction.

The interaction of Entamoeba histolytica trophozoites with collagen involves cell adherence, formation, and release of electron dense granules (EDGs) containing collagenase activity leading to the degradation of the bound protein. The binding is thought to be mediated by an "integrin-like" collagen receptor. Since the signal transduction mechanisms triggered by the collagen-trophozoite interaction are unknown, but clearly involve cytoskeletal organization, we decided to explore the role of protein tyrosine phosphorylation in this process. Collagen induces a time-dependent increase in the phosphorylation of several polypeptides migrating around 67 and 110 kDa. One polypeptide of the high-molecular-weight component was identified as a 125-kDa protein with very similar epitopes to the focal treatment was a 42-kDa polypeptide related to the mitogen activated protein kinase (MAPK) family. Our results suggest that tyrosine phosphorylation is involved in collagen signaling in amoebas and that pp125FAK and p42MAPK homologs may play an active role in turning on the genetic program that enables the parasite to invade its host.

Animals↗
PubMed1996

Effect of melatonin on beta-tubulin and MAP2 expression in NIE-115 cells.

Physiological concentrations of the pineal hormone melatonin induce an increase of microtubules in neuroblastoma NIE-115 cells. This effect is due to an increase in the polymerization state of tubulin. Concomitantly, higher levels of soluble beta-tubulin are present in the treated cells. Unexpectedly, no significant changes in the levels of beta-tubulin or its mRNA occur in the presence of melatonin reflecting perhaps a strict control of its steady state in a physiological context. In contrast, higher amounts of microtubule-associated-protein 2 are found when the cells are exposed to melatonin. These findings support the idea that tubulin polymerization process is one of the targets of melatonin action. Furthermore, our results might explain the increase in the length and number of neurites present in these cells when they are treated with this hormone.

Biopolymers↗
PubMed1996

Changes in rat brain muscarinic receptors after inhibitory avoidance learning.

It is widely accepted that cerebral acetylcholine is necessary for learning and memory, but little is known about the type of muscarinic receptors involved in these functions. To investigate this problem, [3H]-N-methyl-scopolamine which binds to different types of muscarinic receptors, [3H]-Pirenzepine an M1 receptor antagonist, and [3H]-Oxotremorine-M which binds mainly to M2 receptors, were used as ligands to look for possible changes in muscarinic receptor density in neostriatum (NEO), hippocampus (HIP), amygdala (AMY), and temporo-parietal neocortex (CTX), after testing for retention of inhibitory avoidance, trained with high or low footshock intensities. After low reinforcement there was an M1 postsynaptic receptor up-regulation in NEO, HIP, and CTX, and an M2 presynaptic receptor down-regulation in HIP, which suggests a concerted pre- and postsynaptic cholinergic activation in this area. An up-regulation of both M1 and M2 receptors was detected in CTX of low and high footshocked animals, which indicates the presence of a cortical postsynaptic M2 receptor.

Amygdala↗
PubMed1996

Penetrating cardiac injuries.

Penetrating cardiac injuries pose a tremendous challenge to any trauma surgeon. Time, sound judgment, aggressive intervention, and surgical technique are the most important factors contributing to positive outcomes. This article extensively reviews the history, surgical management, and techniques needed to deal with these critical injuries. This year commemorates the one hundredth anniversary of the first successful repair of a cardiac injury.

Animals↗
PubMed1996

Apoptosis: a mechanism of cell killing and lymphoid organ impairment during acute African swine fever virus infection.

Induction of programmed cell death has been described during infection with many different viruses. We have investigated the influence of African swine fever virus (ASFV) on apoptosis of different cell populations during in vitro and in vivo infection. We observed apoptosis in ASFV-infected monocyte/macrophage and peripheral blood mononuclear cell cultures. Apoptosis was demonstrated in these cells by DNA fragmentation, DNA staining and DNA-associated histone fraction detection assays. Flow cytometry analysis of infected cultures also showed morphological and functional alterations, including changes in the cell cycle and percentage of cell fractions stained with propidium iodide. After in vivo infection with three different virulent strains of ASFV, apoptosis of infected cells from the mononuclear phagocytic system and closely related elements from different tissues was observed. Additionally, infected pigs showed an intense degree of apoptosis of lymphocytes, which are not infected by the virus. In lymph nodes and other lymphoid organs, broad bands of apoptotic cells presented typical nuclear changes under light microscopy. The occurrence of DNA fragmentation was confirmed in these tissues using terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling. These findings, together with the pathological observations in infected pigs of a depletion in cell populations in lymphoid organs, suggest that virus interference with programmed cell death plays a central role in pathogenesis of this disease, being responsible for lymphoid organ impairment in acute ASFV infection.

Acute Disease↗
PubMed1996

Tropism of human adenovirus type 5-based vectors in swine and their ability to protect against transmissible gastroenteritis coronavirus.

The infection of epithelia] swine testicle and intestinal porcine epithelial (IPEC-1) cell lines by adenovirus type 5 (Ad5) has been studied in vitro by using an Ad5-luciferase recombinant containing the firefly luciferase gene as a reporter. Porcine cell lines supported Ad5 replication, showing virus titers, kinetics of virus production, and luciferase expression levels similar to those obtained in human 293 cells, which constitutively express the 5'-end 11% of the Ad5 genome. The tropism of Ad5-based vectors in swine and its ability to induce an efficient immune response against heterologous antigens expressed by foreign genes inserted in these vectors has been determined. Ad5 vectors replicate and express heterologous antigens in porcine lungs and mediastinal and mesenteric lymph nodes. Significant levels of heterologous antigen expression were also demonstrated in the small intestine (jejunum and ileum), but Ad5 replication in this organ was very poor, suggesting that Ad vectors undergo an abortive replication in the porcine small intestine. The tissues infected by Ad5 were dependent on the inoculation route. The oronasal route appeared to be best for inoculation of bronchus-associated lymphoid tissue infection, while the intraperitoneal route was best for gut-associated lymphoid tissue infection. Epithelial cells of bronchioles, macrophages, type II pneumocytes, and follicular dendritic cells were identified as targets for Ad5, while epithelial cells of the intestine were not infected by Ad5. Viruses with a deletion from 79.5 to 84.8 map units in the E3 region, with or without heterologous inserted genes, replicated to lower levels in porcine tissues than did wild-type Ad5. It was also shown that an Ad5 recombinant expressing the four antigenic sites (A, B, C, and D) of transmissible gastroenteritis coronavirus (TGEV) spike protein induced in swine immune responses which neutralized TGEV infectivity. In addition, porcine serum from Ad-TGEV-immune animals provide passive protection when mixed with fully virulent TGEV and orally administered to highly susceptible newborn piglets. These results taken together indicate that swine may be a good animal model for human Ad5 lung infection to aid in the evaluation of candidate adenovirus vaccines and that Ad5 may be suitable as a recombinant viral vaccine or for other applications in swine.

Adenoviruses, Human↗
PubMed1996

Influence of the intake of fortified breakfast cereals on dietary habits and nutritional status of Spanish schoolchildren.

A study was performed on the breakfast habits of 200 schoolchildren between 9 and 13 years of age. The subjects were classified into two groups: group C, children who consumed fortified breakfast cereals (65 boys and 35 girls), and group NC, children who did not (64 boys and 36 girls). The different dietary habits and the nutritional status of the two groups were analyzed. Haematological, biochemical, anthropometric, and dietary data were collected, the latter involving a 5-day food record. The children of the C group were found not only to have a more complete and nutritive breakfast, but also showed better dietary patterns for the rest of the day. Their lipid intake (% kJ) was lower and the carbohydrate intake (g/d and % kJ) higher than in the NC children. The intakes of thiamine, pyridoxine, folates, and beta-carotenes were also higher in group C. Better dietary habits were reflected in higher blood levels of some important compounds. Group C children had higher retinol, serum folate, and riboflavin levels than NC children. The percentage of children with hypercholesterolaemia (serum cholesterol > 4.5 mmol/l) was higher amongst those of the NC group: 37% as compared with 18% of the C children.

Adolescent↗