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Biomedical subjects

J L Montero

Publications and source records attributed to J L Montero.

At least 37 records · Page 2Linked to original sources
PubMed1996

Synthesis and biological activity of acylated and telomerized peptides as potential HIV-fixation inhibitors.

In order to inhibit the gp 120-CD4 glycoprotein interaction, a key step of the HIV-infection, we have synthesized a series of N-acylated peptides containing sequences identified in both the viral and lymphocytic proteins, (SDFR, SDAR, RFDSAARFDS, DRADSRRS, PSKLNDRADSRRSLWD, ASTTTNYT). An hydrophobic moiety (capryloyl, palmitoyl acrylamidoundecanoyl) was introduced in the last step of interactive synthesis, in homogeneous or solid phase. The acrylogyl-containing compounds were then telomerized under UV irradiation (DPn observed: 2 to 6). The biological evaluation shown an antiviral effect in vitro for telomerized peptides containing amino diacids such as Glu and Asp.

Acylation↗
PubMed1995

[A low prevalence of antibodies to the hepatitis C virus in stable heterosexual couples].

The prevalence of antibodies against the hepatitis C virus (HCV Ab) was studied in a group of 126 stable heterosexual couples of HCV Ab carriers. Only 1.59% of the couples was positive with no significant differences observed with regard to the prevalences seen in donors from the same area. The HCV Ab positive couples had shared toiletry articles but no other risk factors were detected. The authors conclude that the sexual transmission of the HCV is scarce.

Adolescent↗
PubMed1994

Prediction of further hemorrhage in bleeding peptic ulcer.

OBJECTIVE: To obtain a simple mathematical model able to estimate early the risk of further hemorrhage in bleeding peptic ulcer. METHODS: A prospective study was conducted on 1567 patients admitted for acutely bleeding peptic ulcer. Ten readily available variables were tested for association with further hemorrhage, and then a logistic regression analysis was carried out. RESULTS: Further hemorrhage occurred in 312 (20%) patients. The univariate analyses showed age over 65 yr, male sex, alcoholism, associated disease, hematemesis, endoscopic bleeding stigmata and shock, and blood urea over 90 mg/dl at admission to be significantly associated with continuous hemorrhage or rebleeding (p < 0.05 to p < 0.001). When these were assessed in a multivariate logistic regression analysis, the best fitted model (likelihood ratio test = 9.9; p = 0.5) included four independent variables. Bleeding stigmata (p < 0.001; odds ratio = 3.1), shock (p < 0.001, odds ratio = 2.5), hematemesis (p < 0.001; odds ratio = 1.6) and age over 65 (p = 0.04); odds ratio = 1.3) were associated with high risk of further hemorrhage. CONCLUSIONS: Bleeding stigmata and changes in hemodynamics are confirmed as the most relevant predictors of further hemorrhage. When they are considered with hematemesis and age altogether, other clinical features loss importance for prognosis. By taking advantage of the joint influences of these variables, accuracy of prognosis improves with respect to that obtained when they are considered as individual risk factors.

Aged↗
PubMed1991

Pharmacology of the potent new non-steroidal anti-inflammatory agent aceclofenac.

Aceclofenac (2-[(2,6-dichlorophenyl) amine]phenylacetoxyacetic acid; CAS 89796-99-6) is a new orally effective non-steroidal anti-inflammatory agent of the phenylacetic acid group which showed remarkable anti-inflammatory, analgesic, and antipyretic properties. Hence, aceclofenac possesses a potent inhibitory activity in several models of acute and chronic inflammation in rodents, and resembles indometacin and diclofenac in its pharmacodynamic profile, being superior to naproxen and phenylbutazone. In addition, aceclofenac was found to be highly active against sodium urate-induced synovitis in dogs and adjuvant-induced polyarthritis in rats, both prophylactically and therapeutically. The analgesic effect of aceclofenac on the pain elicited by chemical and mechanical stimuli was nearly equal to or slightly better than that of indometacin and diclofenac. Fever induced by brewer's yeast injection in rats was also markedly suppressed by aceclofenac. In contrast, the acute gastric ulcerogenic activity of aceclofenac was about 2, 4 and 7-fold lesser than that of naproxen, diclofenac, or indometacin, respectively. As a consequence of its high anti-inflammatory activity and lower potential for gastric damage aceclofenac exhibited the most favourable therapeutic ratio in comparison with indometacin, diclofenac, naproxen, and phenylbutazone. These data indicate that aceclofenac could be a potent anti-inflammatory and analgesic agent with a wide margin of safety in clinical practice.

Animals↗
PubMed1990

Pharmaco-toxicological effects of acetaminophen in rodents. Battery of tests to screen potential analgesic acetaminophen derivatives.

The pharmacological effects of acute oral administration of acetaminophen have been extensively evaluated in rodents. Using this drug as reference compound we have also standardized several pharmaco-toxociological tests in order to select new analgesic-antipyretic acetaminophen derivatives. According to the results obtained in this work, the following battery of assays is proposed to screen these compounds: a) pharmacological: antipyretic activity against Brewer's yeast-induced pyresis in rats; analgesic activity against chemical-induced writhings in mice and paw pressure test in rats; b) toxicological: oral acute toxicity in mice with and without phenobarbital pretreatment; determination of SGOT and SGPT activities as well as total bilirubin in mice. The usefulness of this procedure in the evaluation of drug effects is also considered.

Acetaminophen↗
PubMed1988

In vitro study on the contribution of the rat intestine-pancreas to glucose homeostasis.

Insulin release, glucose utilisation and lactate production were investigated using an in vitro perfused rat intestine-pancreas preparation after intraluminal or arterial glucose administration. In the absence of intraluminal glucose administration, both glucose utilisation and lactate production seem to be dependent on the arterial glucose concentration. Despite the different proportions in the portal values of glucose and lactate found at the various arterial glucose concentrations, the percentage of the total carbon atoms from infused glucose recovered in the portal vein remained constant. A significant (p less than 0.01) increase in insulin secretion was observed when the arterial glucose concentration was increased from 5.5 to 16.7 mmol/l. After intraluminal administration of glucose (4 g/kg body weight) both as a bolus or as an infusion, the lactate produced and the insulin released by the preparation were not significantly increased with respect to values measured in the absence of intraluminal glucose load. After intraluminal administration of glucose (1 g/kg body weight) as a bolus, the net translocation of glucose from the lumen to the vascular circuit was apparently reduced when the glucose concentration was increased in the perfusate from 2.75 to 11.0 mmol/l; this reduction could be dependent on an increase in the metabolism of absorbed glucose. In conclusion, the functional unit intestine-pancreas seems to play an important role in glucose homeostasis by elaborating the adequate mixture of glucose and lactate that must reach the liver under the various metabolic conditions.

Animals↗
PubMed1987

Effect of Piracetam on electrocorticogram and local cerebral glucose utilization in the rat.

The effect of Piracetam on hypoxia-induced alterations of cerebral cortex electrogenesis is studied. The results showed protection. As this anti-hypoxidotic property could be linked to Piracetam influence on energy-metabolic processes in the brain, we studied the effect of this nootropic drug on local cerebral glucose utilization (LCGU) by means of a variant of the Sokoloff's technique. Our results showed that Piracetam enhances LCGU. We suggest that both effects, the functional and the metabolic one, are related.

Animals↗
PubMed1987

Chronic food restriction and the circadian rhythms of pituitary-adrenal hormones, growth hormone and thyroid-stimulating hormone.

Adult male Sprague-Dawley rats were subjected to food restriction so that they ate 65% of food ingested by control rats. While control rats had free access to food over the 24-hour period, food-restricted rats were provided with food daily at 10 a.m. The experimental period lasted for 34 days. On day 35, rats from both experimental groups were killed at 08.00, 11.00, 14.00, 24.00 and 02.00 h. Food restriction modified the circadian rhythms of ACTH and corticosterone. In addition, total circulating corticosterone throughout the day was higher in food-restricted than in control rats. In contrast, food restriction resulted in depressed secretion of thyroid-stimulating hormone and growth hormone. The results indicate that time of food availability entrained circadian corticosterone rhythm but not thyroid-stimulating hormone and growth hormone rhythms.

Adrenal Glands↗
PubMed1986

Sensitivity of corticosterone and some metabolic variables to graded levels of low intensity stresses in adult male rats.

Adult male rats were subjected to different acute stressors, whose intensity was gradually increased, and their corticosterone, glucose, and serum lipid levels were studied. Serum corticosterone was sensitive to graded levels of stress intensities. Glucose followed the same trend. However, serum lipid responses were not related to the intensity of stress. Our results indicate that these latter variables were not sensitive indices of the emotional arousal elicited by brief stress stimuli.

Animals↗
PubMed1986

Nicardipine: protection against brain hypoxia.

Nicardipine, a new vasodilator and calcium antagonist, was tested for antihypoxic activity on the central nervous system. Two methods were used: hypobaric hypoxia and alteration of the electrocorticogram by asphyxic anoxia. Both survival time and the impaired electrical signal were improved by nicardipine. These results suggest brain protection by increased cerebral blood supply.

Animals↗
PubMed1984

[Serum profile of bile acids in children with neonatal hepatitis and extrahepatic biliary atresia].

A bile acid analysis by a fluorometric-enzymic method was carried out in serum from infants with neonatal hepatitis and biliary atresia. Serum bile acids were determined in 51 infants: 34 with extrahepatic biliary atresia and 17 with neonatal hepatitis syndrome. The following results were obtained: 1) There were no significant differences between neonatal hepatitis and biliary atresia concerning total serum bile acids. 2) The ratio of trihydroxylated to dihydroxylated bile acids in serum was less than one in 30 patients with biliary atresia and greater than one in 15 patients with neonatal hepatitis. 3) Conventional hepatic tests did not show any statistically significant difference between these types of patients. These results suggest that trihydroxy/dihydroxy bile acid ratio may be of clinical interest to differentiate biliary atresia from neonatal hepatitis in infants.

Bile Acids and Salts↗
PubMed1983

Serum bile acid levels in children with chronic persistent hepatitis and chronic aggressive hepatitis.

A statistical study was carried out to determine if fasting serum bile acid levels are clinically useful in differentiating children with chronic persistent hepatitis from children with chronic aggressive hepatitis. Serum bile acid levels were determined in 27 patients with chronic aggressive hepatitis, 41 with chronic persistent hepatitis and 55 control children. Several other biochemical tests of liver function were also determined in these children. There were significant differences in the mean fasting serum bile acid levels between chronic hepatitis patients and control children (p less than 0.001). These levels were significantly higher for the chronic aggressive group than the chronic persistent hepatitis group (p less than 0.001). Other biochemical 'hepatic function' tests did not show statistically different values between these two groups. Using stepwise discriminant analysis for the biochemical 'liver function' tests studied, only serum bile acid levels are able to distinguish statistically between chronic aggressive hepatitis and chronic persistent hepatitis children. These data suggest that fasting serum bile acid levels may have clinical utility in identifying children with asymptomatic chronic hepatitis and differentiating between chronic aggressive hepatitis and chronic persistent hepatitis children.

Adolescent↗
PubMed1983

Effect of chronic noise or water restriction on weight of body and organs in the rat.

The effect of either chronic noise or water restriction on body weight gain and weight of several glands and organs has been studied in male Wistar rats. The results indicate that chronic noise does not affect the relative weight of glands and organs but it induces a slight decrease in body weight gain. Water restriction provokes a strong decrease in body weight gain and relative weight of the liver while it increases significantly the relative weight of other glands and organs as a likely consequence of the decrease in body mass. Chronic noise does not seems to be a strong stress and it markedly differs from water restriction which is not appropriate as a model of chronic stress.

Animals↗
PubMed1983

Plasma calcitonin concentration in patients treated with chronic dialysis: differences between hemodialysis and CAPD.

We have determined plasma calcitonin levels in 72 chronic dialysis patients and investigated their possible correlations with other parameters of calcium and phosphorus metabolism, including plasma levels of calcium, phosphorus, alkaline phosphatase and parathormone, as well as with the duration of treatment. Forty-one of the patients were being treated with hemodialysis (HD) and thirty-one with continuous ambulatory peritoneal dialysis (CAPD). Increased calcitonin levels were detected in 83% of the HD patients and in 79% of the CAPD group. In the former there was a positive correlation between the levels of calcitonin and the calcium, corrected calcium, alkaline phosphatase and parathormone levels and with the duration of treatment, whereas in the latter the calcitonin levels only correlated with the serum calcium. The patients receiving CAPD also showed significantly lower calcium and calcitonin levels than the HD patients. Our conclusion is that, apart from accumulation due to renal failure, the main factor determining the calcitonin level is the blood calcium level, and that the observed increase might play a role in the physiological protection of bone against the action of parathyroid hormone.

Calcitonin↗
PubMed1981

Pyrazolopyrimidine nucleosides. 12. Synthesis and biological activity of certain pyrazolo[3,4-d]pyrimidine nucleosides related to adenosine.

The chemical synthesis of certain 4-substituted pyrazolo[3,4-d]pyrimidine nucleosides is described. Using 1-(2,3,5-tri-O-acetyl-beta-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidin-4-one (1) as the starting material, the reactive intermediate 4-chloro-1-(2,3,5-tri-O-acetyl-beta-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidine (2) was prepared in excellent yield. Compound 2 served as a versatile precursor for the synthesis of a number of 4-substituted pyrazolo[3,4-d]pyrimidine nucleosides. In antitumor studies of these nucleosides, in vitro and in vivo, it was found that any alteration of the 4-amino substituent of 4-amino-1-beta-D-ribofuranosylpyrazolo[3,4-d]pyrimidine (3) was accompanied by a significant decrease or loss of antitumor activity. On the other hand, introduction of certain substituents at the 3 position of 3 (synthesis reported previously) led to a dramatic increase in antitumor activity in comparison to the parent compound.

Adenosine↗
PubMed1981

Flow cytofluorometric analysis of the effects of new nitrosourea derivatives on proliferation of EMT 6 tumor cells "in vitro".

Examined by flow cytofluorometric analysis, the DNA distribution of EMT 6 tumor cells was highly perturbed after one hour of in vitro incubation with: RPCNU, RFCNU, chlorozotocin (CZT) or 185 (CNCC), four new nitrosourea derivatives. After the treatment with chlorozotocin (20 micrograms/ml) and CNCC (50 micrograms/ml), most of cells were in G2 + M phase and this accumulation lasted more than 48 hours without any restoration before 72 hours. RPCNU (20 micrograms/ml) and RFCNU (50 and 65 micrograms/ml) induced and accumulation of cells in G2 + M phase during 24 hours. The normal state was regained after 48 hours. These reduced rate of progression of the cells through S phase and the G2 block observed after exposure to the new compounds, should, in part, explain their antitumoral activity.

Antineoplastic Agents↗
PubMed1981

Action of three nitrosoureas on human lymphocytes. Hypothesis of a specific effect on lymphocyte subpopulations.

RFCNU [(chloro-2-ethyl)-1-(ribofuranosylisopropylidene-2',3'-paranitrobenzoate-5')-3- nitrosourea], RPCNU [(chloro-2-ethyl)-1-(ribopyranosyltriacetate-2',3',4')-3-nitrosourea] and CCNU [(chloro-2-ethyl)-1-cyclohexyl-3-nitrosourea) were found cytotoxic in vitro for human blood lymphocytes from healthy donors at doses higher than 50 micrograms/ml. Blood lymphocytes from different individuals displayed different behaviors both in their sensitivity to nitrosoureas and in their proliferative response to mitogenic lectins. With pokeweed-mitogen-stimulated lymphocytes the main effect of all three drugs (10 micrograms/ml) was an increase of [3H]-thymidine uptake. This facilitation effect was found only in half of the experiments with phytohemagglutinin-stimulated lymphocytes, while the stimulation by concanavalin A was inhibited under the same conditions. The hypothesis that nitrosoureas might be selectively cytotoxic for a suppressor cell subpopulation might explain the observed increase of thymidine uptake.

Adult↗