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Biomedical subjects

A Ortega

Publications and source records attributed to A Ortega.

At least 145 records · Page 8Linked to original sources
PubMed1995

Characterization of an Na(+)-dependent glutamate/aspartate transporter from cultured Bergmann glia.

The properties of a transport system specific for L-glutamate and L-aspartate activity expressed in Bergmann glia cells from chick cerebellum were examined. The uptake of D-[3H]aspartate was inhibited by the endogenous substrates L-aspartate (Ki = 62 microM) and L-glutamate (Ki = 60 microM). Of the identified uptake inhibitors, L-aspartate-beta-hydroxamate (Ki = 900 microM), L-alpha-aminoadipate (Ki = 2000 microM), 4,4'diisothiocyanatos-tilbene-2,2'-disulphonic acid (DIDS) (Ki = 1000 microM) and 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid (SITS) (Ki = 100 microM) inhibited D-[3H]aspartate uptake. Northern blot analysis, revealed the expression of a chick homologue of a the rat brain L-glutamate/L-aspartate transporter (GLAST). These data suggest that GLAST may be involved in the regulation of the parallel fibre-Purkinje cell synapse ensheathed by Bergmann glia.

ATP-Binding Cassette Transporters↗
PubMed1995

Cost-evaluation model for clinical trials in a hospital pharmacy service.

A cost-evaluation model was applied to clinical trial protocols to estimate their cost for the hospital pharmacy service. The steps taken in the drug management of clinical research were identified. Fixed costs (common to all clinical trials) and variable costs (peculiar to each clinical trial) were determined for each step. The number of patients, the number of operations, the planned services (receptions, storage, drug dispensing), the timing and difficulty of the study (randomization) were included in the variable costs. The economic assessment of these items was based on the costs of the materials and means used, the cost of staff time and finally the cost of drug storage during the clinical trial. This model was applied to 24 clinical trials carried out in the University Clinic of Navarra. 83% of all pharmacy costs of a clinical trial were variable. Drug dispensing, stock management and return drugs account for 94% of the time expended. The approximate cost of the pharmacy providing investigational services was $1,766 per trial or $174 per patient. Drug storage costs were not an important source of expenditure among the variable costs (7.4%). The best way to determine the cost of a trial is to calculate the number of operations.

Clinical Trials as Topic↗
PubMed1995

Excitatory amino acid-induced AP-1 DNA binding activity in Müller glia.

The effect of L-glutamate (L-Glu) and its structural analogs N-methyl-D-aspartate (NMDA), quisqualate (QA), and kainate (KA) on the DNA binding activity of the Activator Protein 1 (AP-1) and the Ca2+/cAMP Responsive Element Binding Protein (CREB) families of transcription factors was examined in cultured chick retinal Müller glia cells. L-Glu, NMDA, and KA evoked a dose and time dependent increase in AP-1 DNA binding activity and had no effect on CREB binding. The order of potency for stimulating AP-1 DNA binding was NMDA > or = Glu > KA >> QA. L-Glu responses were partially blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and by 3-[RS)-2-carboxypiperazin-4-yl)]-propyl-1-phosphonate (CPP) indicating that the increase in DNA binding is mediated both by an alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)/low affinity KA and a NMDA subtypes of L-Glu receptors. Since Müller glia L-Glu receptors are probably mediators of the efficacy of the excitatory transmission in the retina, the present findings suggest that a stimulus-transcription coupling triggered by L-Glu in the glial cells might have a role in the long-term modulation of these synapses.

Animals↗
PubMed1995

Interaction of guanine nucleotides with the kainate binding protein from chick cerebellum.

The interaction of guanine nucleotides with the chick cerebellar kainate binding protein (chKBP) was studied using binding assays, immunoblotting, and in vitro phosphorylation experiments. Guanosine 5'-triphosphate (GTP) was found to reduce [3H]kainic acid (KA) binding in a concentration-dependent manner. Similarly, an inhibition of [3H]GTP binding by KA was observed. No G protein co-purified with chKBP. chKBP phosphorylation by the cAMP-dependent protein kinase (PKA) was prevented both by KA and by GTP. Neither KA nor GTP blocked each other's effect in chKBP phosphorylation. The present findings suggest that chKBP harbours two agonistic binding sites, one in the micromolar range, detected by binding techniques and one in the millimolar range detected by phosphorylation assays. Guanine nucleotides interact with both sites.

Animals↗
PubMed1995

[Resistant tuberculosis in a prison population during 1991-1993].

BACKGROUND: To know the prevalence of resistant tuberculosis and the characteristics of the same in the penitentiary medium in the Madrid area (Spain). METHODS: From March 1, 1991 to August 31, 1993 a prospective study was carried out in patients with isolations of Mycobacterium tuberculosis resistant to some of the common antituberculous drugs within the context of tuberculosis in a penitentiary population attended in the Hospital General Penitenciario (Madrid). Demographic, clinical, analytical, and microbiological data were collected as was that on the antituberculous treatment used. The study of sensitivities was performed by the proportions method. RESULTS: Tuberculosis was diagnosed in 275 patients according to strict microbiological criteria (positive Löwenstein culture). The antibiogram was performed in 218 isolations. Twenty strains resistant to some first line antituberculous drug (9%) (confidence interval [CI] p < 0.05:6-14), 9 of which were found to be multiresistant, were detected in 20 patients. Out of the patients in whom the sensitivity of the isolate was known, 173 had not previously undergone antituberculous treatment. Six of these patients were found to be resistant to isoniazide (3.5%) (CI p < 0.05:1.4-7.7) and 2 patients were resistant to rifampicin (1.2%) (CI p < 0.5:0.2-4.5). The other 45 patients had previously undergone antituberculous drugs with 8 isolates presenting resistance to isoniazide and 11 to rifampicin. Eighty-four percent of the patients with resistant tuberculosis and 90% of the sensitive cases were coinfected with HIV infection with the differences not being statistically significant. The HIV positive patients with resistant tuberculosis showed a mean CD4 positive lymphocytes of 0.76 x 10(9)/l (CI p < 0.5:0.028-0.213) and those with sensitive tuberculosis had 0.165 x 10(9)/l (CI p < 0.05:0.133-0.196) (p < 0.01). CONCLUSIONS: Tuberculosis resistant to common antituberculous drugs was detected in a Spanish penitentiary population. The level of the resistance of the isolations of Mycobacterium tuberculosis should be monitored both inside and outside of the penitentiary medium in an attempt to avoid the progression of resistant tuberculosis within the Community.

Adult↗
PubMed1995

Use of thermal analysis to distinguish magnesium and calcium stimulated ATPase activity in isolated transverse tubules from skeletal muscle.

The presence of calcium stimulated adenosine triphosphatase (Ca2+,Mg(2+)-ATPase) activity in isolated transverse tubule (t-tubule) membranes is distinguished from magnesium adenosine triphosphatase (Mg(2+)-ATPase) activity on the basis of differing thermal stabilities. The Mg(2+)-ATPase is the major protein component of the t-tubule membrane, and it can be difficult to discriminate between the low levels of Ca2+ stimulated ATPase activity found in isolates of t-tubules compared to the much higher Mg(2+)-ATPase activity. Thermal analysis reveals different inactivation temperatures (Ti) for the proteins responsible for ATP dependent calcium transport (Ti = 49 degrees C) and Mg(2+)-ATPase activity (Ti = 57 degrees C) in isolated t-tubule membranes. The differential scanning calorimetry profile of t-tubule membranes consists of three major components with transition temperatures (Tm) of 51 degrees C, 57 degrees C and 63 degrees C. Denaturation of the component with Tm = 57 degrees C correlates with inactivation of Mg(2+)-ATPase activity, and denaturation of the Tm = 51 degrees C component correlates with the inactivation of Ca2+,Mg(2+)-ATPase activity and calcium transport. The functions of the t-tubule membrane component or components that denature with Tm = 63 degrees C have yet to be identified. The lack of stimulation of calcium transport in isolated t-tubules by oxalate, the impermeability of isolated t-tubules to oxalate, and experiments performed on t-tubules with defined amounts of sarcoplasmic reticulum (SR) added suggest that contamination of the isolated t-tubules by SR is unlikely to account for the level of Ca2+,Mg(2+)-ATPase activity detected. The presence of a Ca2+,Mg(2+)-ATPase in the t-tubule membrane would provide a mechanism that may be involved in the partial removal of calcium that is accumulated in the junctional space during muscle relaxation or calcium that is released from the terminal cisternae of sarcoplasmic reticulum during excitation-contraction coupling.

Animals↗
PubMed1995

Fecal diversion for penetrating colon injuries--still the established treatment.

PURPOSE: An analysis of the existing literature on primary repair of colon injuries was undertaken to determine if there is sufficient evidence that this approach is superior to fecal diversion. METHODS: After a thorough literature search, three prospectively randomized studies comparing primary repair with fecal diversion in the management of colon injuries were identified. A variety of factors were examined, including the number of patients in each study arm, morbidity rates, as well as exclusion criteria. An analysis was performed to determine the number of patients required to establish statistical superiority of one procedure over the other. RESULTS: Pooling of the data contained in the aforementioned reports does not provide sufficient statistical power to support the superiority of primary repair of colon injuries. To demonstrate a 5 percent difference between the two approaches, a prospective, randomized study consisting of 200 patients in each arm is necessary. CONCLUSION: The present literature does not support a statistically valid advantage of primary repair over fecal diversion in the management of traumatic colon injuries.

Colon↗
PubMed1995

Improvement of African swine fever virus neutralization assay using recombinant viruses expressing chromogenic marker genes.

Antibody neutralization of African swine fever (ASF) virus measured by a plaque reduction assay presents frequent difficulties because of the absence or delay in plaque formation by many strains, especially low-passage viruses. To overcome this problem, a new ASF virus neutralization test has been developed. The new test consists of a conventional plaque reduction assay in which the viral plaques are detected by expression of marker genes. For the development of this neutralization assay 4 mutant viruses were generated by homologous recombination, containing beta-galactosidase or beta-glucuronidase reporter genes inserted into the thymidine kinase locus of the viral genome. These recombinant viruses have the following advantages with respect to parental viruses: (1) the neutralization assay takes less than a third of the time needed using non-recombinant viruses; (2) the small plaques can be detected more accurately by color contrast; and (3) the neutralization-resistant virus clones can be recovered easily post-plaque counting. Additionally, these recombinant viruses permit differentiation by chromogenic staining of individual infected pig macrophages, the natural host cell for ASF virus, facilitating neutralization assays in these primary cultures as described in cell lines.

African Swine Fever Virus↗
PubMed1995

Internucleosomal DNA cleavage in HeLa cells exposed to cisplatin.

Exposure of HeLa cells to Cisplatin resulted in cell death characteristic of a suicide process known as apoptosis, as stated by morphologic features, extensive and specific DNA fragmentation and in situ end labeling of DNA breaks. The apoptotic cell death was induced timely in a dose-dependent manner, without any primary necrosis at the concentrations used. In contrast to other reports, the death in this cell line was accompanied by low-molecular weight DNA fragmentation. These results and their relevance to the apoptotic process are discussed.

Antineoplastic Agents↗
PubMed1994

AMPA/KA receptor induced AP-1 DNA binding activity in cultured Bergmann glia cells.

The effect of L-glutamate (L-Glu) and its structural analogs kainate (KA) and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) on the DNA binding activity of the activator protein 1 (AP-1) family of transcription factors was examined in cultured chick cerebellar Bergmann glia cells. These agonists evoked a dose- and time-dependent increase in AP-1 DNA binding activity and their responses were blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). The increase in DNA binding is probably mediated by an AMPA/low affinity KA subtype of L-Glu receptor. The synaptic localization of these receptors, their ion channel properties and a stimulus-transcription coupling further strengthen the putative role of glia cells in the modulation of synaptic efficacy and plasticity.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1994

[Disseminated aspergillosis in patients with acquired immunodeficiency syndrome].

Disseminated aspergillosis is very infrequent in patients infected by the human immunodeficiency virus and diagnosis is made usually upon necropsy. The case of a 28 year old male who presented multiple abscesses by Aspergillus sp. in the lung, thyroid glands, spleen, myocardium, pancreas, kidney and in both cerebral hemispheres is presented. The patient also concommitantly showed M. avium in the spleen, liver and central nervous system. The literature was reviewed to evaluate the clinical characteristics and predisposing factors which may contribute to diagnosis and treatment.

AIDS-Related Opportunistic Infections↗
PubMed1994

AMPA/KA receptor expression in radial glia.

The expression of four genes (GluR 1; 2; 3; 4) encoding functional subunits of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/low affinity kainate (KA) subtype of glutamate receptors was investigated in chick radial glia, namely Bergmann and Müller glial cells, using Northern blot analysis with oligonucleotide probes. Both cell types expressed the transcripts GluR 1; 3; 4, whereas the GluR 2 mRNA could not be detected. The synaptic localization of these receptors, their ion-channel properties and their regulation further strengthen the putative role of glial cells in the modulation of synaptic efficacy and plasticity.

Animals↗
PubMed1994

Dengue virus. Detection and pathogeny.

Sequences front a cDNA of dengue virus type 4 were cloned into transcription vectors. These sequences included the E, NS1, NS2A, NS2B, NS3 genes. RNA transcripts produced in vitro from these plasmids were used in hybridization assays to detect dengue viral sequences. With these RNA-probes we have been able to detect molecules of serotype-specific dengue 4 viral RNA. Moreover, the riboprobes detected viral sequences of other serotypes in the following order of sensitivity 4 > 2 > 3 > 1, and might be useful to differentiate serotypes.

Animals↗
PubMed1994

Synaptophysin and neurofilament expression in neurons infected with dengue virus.

The expression of two genes encoding the neuronal specific proteins synaptophysin and high molecular weight neurofilaments was investigated in primary cell cultures of embryonic mouse brain infected with dengue virus type 2, using immunocytochemistry and Western blot analysis with monoclonal antibodies. The viral infection leads to a 20-fold induction in the expression of the mentioned synaptogenesis-related proteins. These results suggest a correlation between virus infection and neuropathology of immature neurons in vivo.

Animals↗
PubMed1994

[Nutrition and cardiovascular diseases in elderly people].

Older age is a vulnerable stage from the nutritional point of view. Nutritional deficiencies are frequent and their consequences serious. That is why restricting diets are dangerous and must be considered with precaution. Though in developed countries the number of elderly people is increasing, the treatment of cardiovascular diseases in this age group is based by extrapolating the recommendations set for adults of minor age, and this may be not correct. High cholesterol and saturated fat intakes are recognized as harmful, but diet restrictions can lead to other nutritional deficiencies that can be damaging in relation to cardiovascular diseases. To improve the diet can be of great help in this sense. Diet restrictions concerning one or more foodstuffs must be introduced with caution and control, watching the nutritional status of the elderly person. It must be avoided that the fight against cardiovascular diseases may lead to other nutritional deficiencies with similar or worse sanitary repercussions.

Age Factors↗
PubMed1993

Glutamate stimulates [3H]phorbol 12,13-dibutyrate binding in cultured Bergmann glia cells.

The effect of L-glutamate and its structural analog kainate on the binding of [3H]phorbol 12,13-dibutyrate was examined in cultured chick cerebellar Bergmann glia cells. Both glutamate and kainate evoke a dose-dependent increase in the maximal number of binding sites for [3H]phorbol 12,13-dibutyrate in intact cells reflecting an activation and translocation of the Ca2+/diacylglycerol-dependent protein kinase (protein kinase C, PKC) from cytosol to the plasma membrane. Glutamate and kainate responses were blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) indicating that the increase in [3H]phorbol 12,13-dibutyrate binding sites is mediated by an alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainate receptor. Since Bergmann glia AMPA/kainate receptors are probably mediators of the efficacy of the parallel fiber-Purkinje cell synapse, the present findings suggest that the Ca2+/PKC signalling cascade might play a role in such modulation.

Animals↗