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Biomedical subjects

A Castro

Publications and source records attributed to A Castro.

At least 325 records · Page 18Linked to original sources
PubMed1994

Antipoliovirus activity of isothiazole derivatives: mode of action of 5,5'-diphenyl-3,3'-diisothiazole disulfide (DID).

In this report we describe the antiviral activity of 5,5'-diphenyl-3,3'-diisothiazole disulfide (DID) and discuss its mode of action. DID selectively inhibits the replication of poliovirus type 1 (therapeutic index = 255) by affecting some early process of the virus growth cycle. The compound does not interfere with adsorption and internalization of virus to HEp-2 cells, nor with uncoating of the viral RNA. However, no viral RNA synthesis occurs after 2 h post-infection in the presence of 50 microM DID. Thus, we investigated some molecular events in poliovirus replication occurring between uncoating and viral RNA synthesis. In our experimental design, we studied the activity of RNA polymerase complex isolated from HEp-2 infected cells in the presence or absence of DID. Our results showed that the RNA polymerase complex was formed in the presence of DID. On the contrary, DID markedly inhibited poliovirus RNA synthesis in a cell-free system using RNA polymerase complex isolated from infected cells. These findings indicate that DID may exert its antiviral activity by preventing viral RNA chain elongation via the inhibition of replicase activity and/or interfering with viral RNA polymerase complex.

Antiviral Agents↗
PubMed1994

The effects of cocaine and its metabolites on the production of reactive oxygen and reactive nitrogen intermediates.

Cocaine, a naturally occurring alkaloid, is known to affect the immune system. The present authors have demonstrated that peritoneal macrophages, isolated from mice injected with cocaine, have an increased capacity for the production of reactive oxygen intermediates (ROI) and a decreased capacity for the production of reactive nitrogen intermediates (RNI). The present studies were done to determine the effects of certain cocaine metabolites on the induction of ROI and RNI by peritoneal macrophages. C57BL/6 mice were injected i.p. with either saline or 5 mg/kg of one of the following: cocaine, norcocaine, benzoylecgonine, ecgonine methyl ester HCl or ecgonine HCl. The ROI were measured using a chemiluminescence assay and the RNI were measured as nitrite secretion following exposure of isolated M phi to interferon gamma and LPS. Isolated peritoneal M phi from mice injected i.p. with cocaine, norcocaine and benzoylecgonine exhibited an increase in the production of ROI and a concomitant decrease in the production of RNI. However, injections of either ecgonine methylester HCl or ecgonine HCl had no effect on the induction of either ROI or RNI by murine peritoneal M phi. The cocaine metabolites, norcocaine and benzoylecgonine, have been reported to cause hepatic and/or cerebral toxicity. The present study also demonstrated that injection of these metabolites in vivo, also altered M phi functions which were measured in vitro.

Animals↗
PubMed1994

Detection of immunoglobulin G to measles virus, rubella virus, and mumps virus in serum samples and in microquantities of whole blood dried on filter paper.

Immunity to measles virus, rubella virus, and mumps virus was determined by EIA in serum samples and in dried whole blood specimens spotted on Whatman filter paper (5 mm in diameter). Both specimens were obtained from each patient by venepuncture and finger prick. Ten microliters of whole blood is enough to detect antibodies to these three different viruses. The comparison of the results obtained by EIA from 227 serum and whole blood samples have demonstrated close agreement: 98.6% for measles virus, 99.1% for rubella virus, and 96.0% for mumps virus. Moreover, 96 whole blood samples can be tested in a microtiter plate and can be stored at room temperature for 15 days or at +4 degrees C for several months. Therefore, whole blood dried on filter paper is a convenient alternative method for collecting and transporting specimens, it is easier and safer than venepuncture, and could be used for large-scale epidemiological studies, especially in newborns. This method could solve the problem of sampling, especially in young children, and could simplify studies of vaccine efficacy.

Adult↗
PubMed1994

Intracellular calcium concentration in vascular smooth muscle cells of rats with cirrhosis.

A decreased pressor response to endogenous vasoconstrictors, such as angiotensin II and vasopressin, is a characteristic finding in cirrhosis with ascites; this has been considered as partially responsible for the arteriolar vasodilation present in this disease. Previous investigations suggested that this abnormality is due to a post-receptor defect leading to altered intracellular Ca2+ mobilization. To assess this hypothesis, vascular responsiveness to angiotensin II (3.10(-8) M) and intracellular Ca2+ concentration in basal conditions and following angiotensin II (1-100 nM) and vasopressin stimulation (100 nM) were measured in aortic rings and in primary cultured aortic vascular smooth muscle cells, respectively. The study was carried out in 43 control rats and 40 rats with CCl4-induced cirrhosis and ascites. Cells were grown to confluence on glass cover slips and then loaded with Fura-2, a fluorescent intracellular Ca2+ indicator, for continuous monitoring of intracellular Ca2+ concentration. A decreased constrictor response to angiotensin II was detected in cirrhotic aortic rings in comparison to control rings (increase in tension: 31 +/- 5 vs 79 +/- 14 mg, p < 0.005). No differences in intracellular Ca2+ concentration between cirrhotic and control cells were observed in basal conditions (104 +/- 6 and 100 +/- 3 nM, respectively). Angiotensin II administration to cirrhotic vascular smooth muscle cells had a dose-dependent biphasic effect consisting of a rapid increase, followed by return to a sustained level significantly higher than the basal value. This response was identical to that observed in control vascular smooth muscle cells. Similar findings were obtained following vasopressin stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1994

One year's experience with an acute pain service in a Spanish University Clinic hospital.

We describe the experience of the acute pain service of the University Hospital of Galicia, Spain since its inception. We have treated 1214 patients using either patient-controlled analgesia (PCA) with morphine (72%), or patient-controlled epidural analgesia with fentanyl + bupivacaine (22%). Three hundred and five patients had minor complications, mainly pruritus (35%) in patients with patient-controlled epidural analgesia. Three (0.33%) patients using PCA had respiratory depression treated with naloxone; no patient with patient-controlled epidural analgesia had respiratory depression. In our experience the creation of an acute pain service and the associated development of pain-treatment protocols and the training of hospital personnel produced excellent results.

Academic Medical Centers↗