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Biomedical subjects

E García

Publications and source records attributed to E García.

At least 181 records · Page 10Linked to original sources
PubMed1993

Ketoisocaproate contamination errors in protein synthesis determinations using L[1-14C]leucine.

Protein synthesis rate determinations in vivo using L-[1-14C]-leucine may be underestimated because of contamination by radioactive ketoisocaproate (KIC) resulting from leucine metabolism. The aim of this work was to set up a reliable method to determine the KIC/leucine radioactivity ratio in protein-free homogenates, and to apply it to study the extent of the protein synthesis ratio error due to KIC contamination. Cation-exchange chromatography using Dowex AG 50W-X8 resin was used to separate KIC from leucine, eluting KIC with water and leucine with 4 M ammonia. The errors found in the protein synthesis ratio were 6.20% in liver and 2.34% in jejunum.

Animals↗
PubMed1993

Responsiveness to D-glucose in neurosecretory cells of crustaceans.

1. An electrophysiological study of the D-glucose sensitivity of X-organ (XO) neurosecretory cell bodies in crayfish was carried out with the use of microelectrodes, perforated, and cell-attached patch-clamp techniques. 2. Glucose depolarizes the membrane potential of XO cells in a concentration-dependent manner. 3. Depolarization produced by glucose initiates a change in the pattern of electrical activity. Silent cells began to discharge action potentials. When bursting cells are depolarized by glucose, their action potentials are no longer grouped in bursts or disappear entirely. 4. Although the membrane potential returns to its initial value after removing glucose from the bath, discharge patterns of the cells may remain different. This suggests that besides the depolarizing effect, once the cells have been exposed to glucose, the sugar switches on a process that is maintained for a long time. 5. Glucose produced a reduction of membrane steady-state conductance, and a shift of reversal potential of membrane currents to a more positive value. 6. Depolarization induced by D-glucose appears to be related with a closure of potassium channels. 7. Glucose effect was thought to be generated by a product of metabolism that would act as intracellular mediator.

Animals↗
PubMed1993

[Endoscopic prosthesis insertion in the palliative treatment of malignant esophageal stenosis. (Endoscopic esophageal prosthesis)].

We report our experience with endoscopic esophageal prosthesis in the treatment of 82 patients with advanced malignant oesophageal stenosis. The cause of the stenosis was an esophageal or esophagogastric cancer in 75 cases and a bronchogenic cancer in 7 patients. In 18 cases a tracheobronchial fistula was also present. A silicone tube (Atkinson) was used in 58 patients, a polyvinyl tube (Wilson-Cook) in 22 cases and a self-expanding tube in the remaining 2 patients. There was no technical failure in the insertion of the prosthesis. A normal feeding was possible in 71 of the 82 patients (86%) within 48 after the intubation. Major complications occurred in 8 cases (9.7%), 4 patients with esophageal perforation and 4 cases with aspiration bronchopneumonia. Postoperative mortality rate was 7.3%, one patient with perforation, 3 cases with aspiration bronchopneumonia and 2 patients with sepsis. The prosthesis partially displaced in 9 cases, but could be endoscopically replaced in all of them. The displacement of the prosthesis was complete in 3 patients, one of which needed a surgical procedure to remove the tube. The prosthesis was bunged up by a solid meal bolus in 4 cases, but an endoscopic procedure was successful in removing the bolus. Therapy with laser was necessary in two cases with self-expanding prosthesis obstructed by tumoral growth. We conclude that, in malignant esophageal stenosis, the endoscopic implantation of esophageal endoprosthesis is an effective, cheap and relatively safe palliative therapeutic alternative with a low postoperative mortality rate.

Adult↗
PubMed1993

[The effect of sepsis on liver protein synthesis].

A study was made of the possible influence of sepsis on liver protein synthesis in septic and control rats, fed either parenterally (TPN) or with water and feed available "ad libitum". Liver protein synthesis was determined using the single massive dose method. In experiment I, the septic and control animals received TPN for twenty-four hours: in experiment II water and food was available to them "ad libitum". Twenty-four hours after the sepsis occurred, the animals were injected with a massive dose of 14C-labelled leucine, and slaughtered by decapitation. The septic animals with water and feed available "ad libitum" were fasted voluntarily without any intake. This group of fasted septic animals was the only one which lost weight. Liver protein synthesis increased in septic animals in comparison with the control animals, whether receiving TPN (112.2 +/- 8/78.5 +/- 13) or with "ad libitum" nutrition (97.2 +/- 15/60.8 +/- 8). The increased liver protein synthesis in the septic animals was modified (although with reduced significance) by parenteral nutrition (112.2 +/- 8/97.2 +/- 15). Our results suggest that sepsis increases liver protein synthesis, and that this protein synthesis may be enhanced by parenteral nutrition.

Animals↗
PubMed1993

[Efficacy and secondary effects of chronic treatment with amiodarone].

Long-term therapy with amiodarone has been associated with a high incidence of adverse side effects, that precludes its indication for common cardiac arrhythmias. We have prospectively studied 218 patients (pts), aged 32-87 years, under chronic amiodarone therapy that were followed for 2 years and evaluated for efficacy and adverse side effects. Previous amiodarone treatment ranged from 1 to 135 months. Cardiac arrhythmias were paroxysmal AF (PAF) in 120 pts, sustained VT (SVT) in 36 pts, paroxysmal supraventricular tachycardia (PSVT) in 21 pts, unsustained VT (UVT) in 18 pts and miscellaneous in 23 pts. Amiodarone doses ranged from 500 to 4200 mg per week. Amiodarone was effective in 65% of all patients. No difference was observed between efficacy and type of arrhythmia. Dermatologic toxicity was found in 36%, neurologic toxicity in 23%, thyroid toxicity in 13.4% and pulmonary fibrosis en 2.5% of pts. Amiodarone was discontinued routinely when pulmonary toxicity was present. We conclude that amiodarone therapy is effective in a wide spectrum of arrhythmias. Although drug therapy was associated with a high incidence of adverse side effects, these did not preclude continuation of treatment.

Adult↗
PubMed1993

[Esophageal pseudoachalasia related to a neoplasm].

Differential diagnosis between idiopathic achalasia and esophageal pseudoachalasia is difficult to perform. One hundred and forty-four consecutive patients with a clinical diagnosis of primary esophageal motor disorder have been evaluated for pneumatic dilatation of the cardias. Of them, 6 (4.1%) have been finally diagnosed of esophageal pseudoachalasia with carcinoma of the cardias, although in four cases more than one biopsy procedure was needed to establish the diagnosis. The clinical data--higher age, shorter clinical history and higher weight loss--, the higher pressure of the lower esophageal sphincter and the failure of the dilatation suggested the diagnosis, but were uncertain findings. Esophageal biopsy is the only objective method to obtain a definitive diagnosis and should be performed in every patient with an esophageal motor disorder evaluated for dilatation of the cardias and, if negative, it should be repeated when malignancy is suggested by available data.

Aged↗
PubMed1992

Structural analysis and biological significance of the cell wall lytic enzymes of Streptococcus pneumoniae and its bacteriophage.

The development of an appropriate technique for the identification of autolysin-defective mutants of pneumococcus has been a fundamental step to carry out studies on the molecular characteristics of the lytic enzymes of Streptococcus pneumoniae and its bacteriophage. Our results show that the principal pneumococcal autolysin (an amidase) is responsible for the separation of the daughter cells at the end of the cell division. On the other hand, this system provides a reliable experimental model to support the extended idea concerning the modular organization of most proteins. The comparative analyses of the deduced amino acid sequences of these enzymes, as well as the construction of functional chimeric phage-bacterial enzymes, demonstrate that the C-terminal domain, which contains a large number of repeated amino acid motifs, is the substrate-binding domain, whereas the N-terminal domain provides enzymatic specificity. We propose that the pneumococcal lytic enzymes have evolved by modular exchange providing examples of the types of novel genes that the bacteria or the phage might create to allow them to become adapted to new environmental situations.

Amino Acid Sequence↗
PubMed1992

A DNA polymerase from maize axes: its purification and possible role.

Three different DNA polymerase activities can be resolved by passing a protein extract from 24 h imbibed maize axes through DEAE-cellulose. These activities have been numbered 1, 2 and 3, according to their elution order. One of them, DNA polymerase 2, elutes at 100-120 mM phosphates. This enzyme was further purified by passing it through Heparin-Sepharose, Sephacryl S-300 and DNA cellulose. Purification was nearly 5000-fold. The enzyme needs Mg2+, is stimulated by K+, has an optimum pH of 7.0 and its optimum temperature is 30-37 degrees C. Specific inhibitors for different types of polymerases, such as aphidicolin, dideoxythymidine triphosphate and N-ethyl maleimide, gave intermediate values of inhibition, making impossible the definition of the type of enzyme purified by its inhibitory pattern. SDS-PAGE indicated the presence of several bands of molecular masses of 28-40, 56 and 15 kDa. Most of these bands could be visualized when proteins from crude extracts were analyzed by western blot, using an antibody against calf thymus DNA polymerase alpha. A high molecular mass (around 500 kDa) was calculated by western blot of native gels using the same antibody. Finally, specific activity of this enzyme increased 100-fold during maize germination whereas polymerase 3 virtually did not increase. Furthermore, immunoprecipitation experiments with the antipolymerase alpha-antibody showed a decrease in DNA polymerase activity by 70%. The possibility that polymerase 2 is a replicative enzyme is discussed.

DNA-Directed DNA Polymerase↗
PubMed1992

Impairment by cyclosporin A of reperfusion-induced arrhythmias.

This study introduces the immunosuppressor, cyclosporin A, as a cardioprotective drug. This effect was analyzed during development of reperfusion/induced arrhythmias after 5-min period of coronary ligation in hearts of rats under anesthesia. The results indicate that cyclosporin, when given before coronary occlusion, at a dose of 20 mg/kg, effectively protects against the high incidence of arrhythmias and the fall in blood pressure induced by reperfusion. In addition, in inhibits the delivery of lactic dehydrogenase and creatine kinase enzymes to the plasma. We propose that the protective effect could be related with its well documented action to restrain Ca(2+)-induced damage of mitochondrial functions.

Animals↗
PubMed1992

Quantitative structure-mutagenic activity relationships of triazino indole derivatives.

The mutagenicity of 3-(4'-benzylidenamino)-5H-1,2,3-triazin[5,4-b]-indol-4-one derivatives, new compounds with considerable platelet antiaggregating activity, was assayed with the Ames test using the Salmonella typhimurium strains TA97, TA98, TA100 and TA102. The adaptive least-squares method (ALS method) was used to carry out a quantitative structure-activity relationship (QSAR) analysis. Three equations, based on 10 congeners, were found for strains TA97, TA98 and TA100. The results suggest that lipophilicity of the substituent decreases the mutagenicity of the series.

Carcinogenicity Tests↗
PubMed1992

Bacterial mutagenic evaluation of a series of 4' substituted derivatives of 3-benzylidenamino-5H-1,2,3-triazin[5,4b]indol-4-one.

The mutagenicity of ten triazinoindole derivatives was studied in bacteria. The compounds form part of a 3-(4'-substituted-benzylidenamino)-5H-1,2,3-triazin[5,4-b]in dol-4-one series and differ in the physicochemical properties of the substituent at the 4' position of the benzylidenamino group: -H, -OH, -COOH, -OCH3, -COOCH3, -NHCOCH3, -C1, -NO2, -C6H5, and -OC6H5. They were tested in the TA97, TA98, TA100, and TA102 strains of Salmonella typhimurium, both with and without metabolic activation, using the preincubation procedure. Only the derivatives with phenyl and phenoxy substituents were non-mutagenic. The remaining compounds significantly increased the number of His+ revertants and showed three patterns of activity based upon their mutagenic potency and their response to metabolic activation. Size and hydrophobicity of the 4'-substituents are the physicochemical characteristics that most differentiate the mutagenic triazinoindole derivatives from the nonmutagenic ones.

Frameshift Mutation↗
PubMed1992

Influence of the triazine ring on the mutagenicity of triazinoindoles and some congeners.

Three compounds, which could be considered as precursors or derivatives of the 3-(4'-substituted-benzylidenamino)5H- 1,2,3-triazin[5,4b]indol-4-one series, were selected from the study of their mutagenic activity. Ames tests were performed study of their mutagenic activity. Ames tests were performed using the Salmonella typhimurium strains TA97, TA98, TA100, and TA102, according to the preincubation procedure, both with and without metabolic activation. The 3-amino-5H-1,2,3-triazin[5,4b]indol-4-one has been shown to be a strong S9-independent mutagen, which reverts frameshift and substitution mutations. Nevertheless its potency increases with the addition of microsomal fraction. In contrast, the 2-benzyliden-1-(3-aminoindol)-2-carbohydrazide and the 3-aminoindol-2-carbohydrazide congeners were not mutagenic. These results suggest that the 1,2,3-triazine ring is the principle substructure responsible for the mutagenicity of the triazinoindole congeners studied.

Hydrazines↗
PubMed1992

In vivo potentiation of atracurium neuromuscular blockade by nimodipine in rabbits.

The interaction between nimodipine, a calcium channel blocker, used for the treatment of subarachnoid haemorrhage, and atracurium, was studied in rabbits. An intravenous dose of 0.1 mg.kg-1 of nimodipine given over 3 min caused a potentiation of the neuromuscular blocking action of atracurium (administered at an infusion rate of 7.5 micrograms.kg-1.min-1), measured on the indirectly stimulated tibialis-anterior muscle of the animal. (ED50)inf and (ED95)inf were significantly reduced (30.7% and 23.3%) in nimodipine-treated animals (P less than 0.05 and P less than 0.02, respectively). No changes were observed in recovery rate.

Animals↗
PubMed1992

[Factors associated with the failure to use condoms among a population of parenteral drug addicts].

Use of condom in sexual intercourse by intravenous drug users has been assessed among a clinical population (n = 139). The multiple logistic regression results show that being a female (OR = 5.1, 95% CI = 2.0-13.2), on drug dependence for a 5-year period or more (OR = 3.0; 95% CI = 1.3-6.9) correlates with non-condom use. Less than 25% of females use condom in their sexual contacts. On the contrary a higher educational level seems to protect subjects against non-condom use (R = 0.3; 95% CI = 0.1-0.8). The most parsimonious model fitting to data at hand includes such variables as sex, educational level, partnership and frequency of sexual intercourse, as well as years on addiction. Other set of variables such as living and working status, age, and previous sexually-transmitted diseases experience are not required for the final model. Emphasis is placed on the need for developing programs aimed at modifying the high risk behavior intravenous drug users resort to in their sexual intercourse, stressing that the main dissemination cause of the human immunodeficiency virus among such a population is due to their sharing drug injections equipment.

Adult↗
PubMed1992

[Isolated mesenteric tuberculosis as the first manifestation of AIDS].

We report a case of mesenteric tuberculosis. Two painful abdominal masses and fever were the first manifestation of disease. Diagnosis was obtained by aspirative punction of a mesenteric adenopathy guided by ultrasonography. AIDS risk factors were not recognized by anamnesis but serum HIV antibodies were detected. Thus, extrapulmonary tuberculosis and the finding of HIV-Ab confirmed the diagnosis of AIDS in our patient. It is necessary to assay for HIV-Ab in extrapulmonary tuberculosis, especially when mesenteric tuberculosis is present.

Acquired Immunodeficiency Syndrome↗
PubMed1992

[Effect of growth hormone and parenteral nutrition on the catabolic phase following major digestive surgery].

The purpose of the present study was to determine if the administration of a biosynthetic human growth hormone (bGH) was able to enhance the efficacy of total parenteral nutrition (PN). Patients (n = 38) who had undergone major gastrointestinal surgery were randomly divided in two groups. Group I (n = 20) treated only with PN and Group II (n = 18) treated as in Group I plus bGH (4 UI/daily). Our study shows that the administration of bGH produces a significant increase in serum levels of growth hormone and Somatomedin-C. It also caused a positive nitrogen balance from the first 24 hours on (p less than 0.01). In Group II on day 12 after operation a statistically significant increase in transferrin (p less than 0.05), albumin (p less than 0.01) and total proteins (p less than 0.02) was observed. Our study suggest that the administration of bGH produces, perhaps through Somatomedin-C as mediator, an increase in protein synthesis.

Adult↗