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Biomedical subjects

M J Alfaro

Publications and source records attributed to M J Alfaro.

35 records · Page 2Linked to original sources
PubMed1993

Effect of Bay K 8644 on the synthesis and metabolism of dopamine and 5-hydroxytryptamine in various brain areas of the rat.

The effects of Bay K 8644 (1, 2 and 4 mg kg-1, i.p.) on the synthesis and metabolism of dopamine and 5-hydroxytryptamine (5-HT) in rat brain after m-hydroxybenzylhydrazine administration were studied. Bay K 8644 (2 and 4 mg kg-1, i.p.) caused an increase in the synthesis of both dopamine in the striatum and 5-HT in the midbrain and striatum, measured as the accumulation of 3,4-dihydroxyphenylalanine (dopa) and 5-hydroxytryptophan, respectively. Moreover, Bay K 8644 at the dose of 4 mg kg-1 increased the turnover of dopamine in the striatum and of 5-HT in midbrain and striatum. These neurochemical changes were antagonized by the calcium channel antagonist nimodipine (10 mg kg-1, i.p.). It is concluded that dihydropyridine receptors may mediate the brain region-specific changes in the dopaminergic and 5-HT-ergic neurotransmission which occur following activation of neuronal calcium channels.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1992

Analgesic effect of salmon-calcitonin administered by two routes. Effect on morphine analgesia.

We compared the analgesia induced by intraperitoneally (i.p.) and intracerebroventricularly (i.c.v.) administered salmon-calcitonin (S-CT), using the hot-plate test and the writhing test. The influence of the route of administration on the analgesia induced by morphine was also studied. After i.p. administration the analgesic effect was observed only in the writhing test. When S-CT was administered i.c.v., analgesia was observed in both tests, although it was greater in the writhing test than in the hot-plate test. I.c.v. injected S-CT increased the analgesia of i.p. injected morphine. Our results provide new information about the analgesic effect of S-CT and suggest that central mechanisms are involved.

Analgesia↗
PubMed1991

Effect of cinitapride in isolated ileum obtained from guinea-pigs treated with morphine.

1. Cinitapride enhanced the contractile response induced by electrical stimulation in the guinea-pig myenteric plexus-longitudinal muscle strip preparations. 2. The contractile force was significantly increased in strips pretreated with morphine "in vitro" and in tolerant strips. 3. However when tissues were obtained from tolerant guinea-pigs and morphine was not added to the organ bath (morphine-abstinence), the cinitapride effect was significantly decreased. 4. Although further work is required to explain the changes in the effect of cinitapride after acute morphine treatment and in morphine tolerant tissues, the changes observed suggest that some of the cinitapride effects could be linked with the peripheral opioid system.

Animals↗
PubMed1991

Calcitonin increases the inhibitory effect of opioids in guinea-pig ileum.

1. The relationship between salmon calcitonin (S-CT) and opioid system was studied in isolated guinea-pig ileum. 2. Addition of S-CT (0.1 to 1.6 U/ml) to the organ bath did not modify the amplitude of the contractile response induces by electrical stimulation. 3. However, when tissues were incubated 30 min with S-CT (0.1 U/ml), the inhibitory effect of the release of endogenous opioids, met-enkephalin (1 microM) and morphine (0.2 microM) was significantly increased. 4. Our results suggest that some of the analgesic effects of S-CT could be attributed to an up-regulation of the opioid receptors.

Animals↗
PubMed1991

The effect of dihydropyridine calcium channel agents on 5-HT metabolism in the CNS of the rat.

The effects of dihydropyridines on the levels of 5-hydroxytryptamine (5-HT) and 5-hydroxy-3-indole acetic acid (5-HIAA) in the spinal cord and various brain regions of the rat have been studied. Nimodipine, nitrendipine and nifedipine (10 mg kg-1), nisoldipine (5 mg kg-1), and BAY K8644 (0.2 and 2 mg kg-1) were administered i.p. 1 h before killing. The administration of nifedipine and nitrendipine increased 5-HT turnover in all of the areas studied except for the spinal cord. Nisoldipine increased 5-HT turnover in midbrain, hippocampus and cortex, while the effect of nimodipine was restricted to midbrain. BAY K8644 at 2 mg kg-1 produced the same effects as nifedipine and nitrendipine; however, at low doses (0.2 mg kg-1), this compound increased 5-HT turnover only in midbrain and medulla oblongata. These results indicate that both dihydropyridine calcium channel agonist and antagonists are able to activate the 5-HT-ergic system in the central nervous system of the rat in-vivo. Therefore, it seems likely that such effects could be due to indirect actions or to interactions of the compounds with receptors other than the voltage-sensitive calcium channels.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1991

[Abscess of the psoas: a not-so-rare entity. Analysis of a series of 18 cases].

We have studied 18 patients with abscess at the psoas who had a mean age of 43.55 +/- 18.9 years and a predominance of males (77.8%). In nine cases the abscess was secondary to a lumbar discal spondylitis, in 5 cases to a sacroiliitis, in one case to abdominal disorder, and 3 cases the abscess was considered of a primary origin. The etiologic agents were S. aureus (8 cases), E. granulosus (5 cases), M. tuberculosis (3 cases), and B. melitensis (1 case). In one patient the infective agent was not isolated and in two cases the abscesses were infected by E. granulosus and P. aeruginosa. The clinical picture on admission was studied in all cases. Microbiological and pathologic analysis of the abscess allowed to establish the diagnosis in 11 cases (yield: 84.6%). Computerized axial tomography was the most useful imaging technique. Antimicrobial treatment was undertaken in 16 cases. Four patients recovered with pharmacological treatment alone. Surgical treatment was performed in 13 cases. Aspirative punction/drainage was carried in only one patient. The clinical course was favourable in 16 patients (88.9%). Our data indicate that the incidence of abscess of the psoas in cases of intraabdominal infections is low. In our series the incidence of abscesses secondary to hydatidosis is relatively high.

Abscess↗
PubMed1990

Dihydropyridines on guinea-pig ileum.

1. The effects of three dihydropyridine derivates were studied and compared with those of nifedipine in guinea-pig ileum. 2. Nifedipine, nimodipine, nitrendipine (25-200 nM) and nisoldipine (10-80 nM) produced a dose-dependent inhibition of the contractile responses induced by single pulse stimulation, acetylcholine (1 microM) and high-K (50 mM). 3. From these experiments it is concluded that nimodipine and nitrendipine, like nifedipine, produced a similar and potent inhibitory effect of the contractile responses induced in the guinea-pig ileum. 4. Nisoldipine resulted to be the most active agent.

Acetylcholine↗
PubMed1990

Effect of clonidine, nimodipine and diltiazem on the in vitro opioid withdrawal response in the guinea-pig ileum.

1. The effects of clonidine, nimodipine and diltiazem, on the in vitro withdrawal contracture induced by naloxone in the guinea-pig ileum obtained from morphine-dependent animals, were evaluated. 2. The in vitro incubation with clonidine (0.01, 0.1 and 1 microM), diltiazem (0.25, 0.1 and 1 microns) or nimodipine (0.05, 0.1 and 1 microns) reduced significantly the force of the contracture induced by naloxone in the morphine-dependent guinea-pig ileum. 3. The intraperitoneal administration of clonidine (0.3 mg kg-1), nimodipine (5 mg kg-1) or diltiazem (20 mg kg-1) reduced the contractile response induced by naloxone in the morphine-dependent guinea-pig ileum. 4. It is concluded that at least part of the effect of clonidine, nimodipine and diltiazem on withdrawal contractures is mediated via a peripheral, rather than a central site of action. Even though, the mechanism responsible for the effect of the calcium channel blockers differs from that of alpha 2-adrenoceptor agonists, all of the drugs tested prevented the contracture induced by naloxone in morphine-dependent guinea-pig ileum.

Animals↗
PubMed1988

Preoperative identification of patients at high risk of deep venous thrombosis despite prophylaxis in total hip replacement.

Clinical and laboratory variables were measured on the day before operation in 111 patients who underwent total hip replacement prophylactically treated with acetylsalicylic acid or heparin-dihydroergotamine. Postoperative deep vein thrombosis (DVT) was detected in 16 patients by ascending venography. Stepwise logistic discriminant analysis was used to identify DVT predicting factors. Three such factors, fibrinogen degradation products (FDP), plasminogen activator inhibitor (PA-inhibitor) and tissue type plasminogen activator (t-PA), were found to be significantly associated with DVT and were used to construct a predictive index. The predictive index, I = -2.09 + 0.46 (FDP) + 1.39 (PA-inhibitor) -0.24 (t-PA), was 100% sensitive and 95% specific in the prediction of DVT. This index would allow for identification of those patients in whom routine prophylaxis would be sufficient and for selecting those in whom more effective prophylactic regimens would be necessary.

Adult↗
PubMed1988

A comparison of the effects of oxodipine and nifedipine on rat vas deferens.

The effects of oxodipine, a new dihydropyridine, were studied and compared with those of nifedipine in the complete vasa deferentia and in the prostatic and epididymal halves of the rat vas deferens. Oxodipine and nifedipine, 10(-9) -10(-6)M, produced a dose-dependent inhibition of the contractile responses induced by single pulse stimulation, noradrenaline (3 x 10(-5)M) and high-K (50 mM). The inhibitory effects of oxodipine were significantly reduced in high Ca media. From these experiments it is concluded that oxodipine, like nifedipine, produced a similar and potent inhibitory effect of the contractile responses induced in the rat vas deferens.

Animals↗
PubMed1988

Effect of oxodipine and nifedipine on guinea-pig ileum.

1. The effects of oxodipine, a new dihydropyridine, were studied and compared with those of nifedipine in guinea-pig ileum. 2. Oxodipine and nifedipine, 10(-8)-10(-7) M, produced a dose-dependent inhibition of the contractile responses induced by single pulse stimulation, acetylcholine and histamine. 3. From these experiments it is concluded that oxodipine like nifedipine produced a similar and potent inhibitory effect of the contractile responses induced in guinea-pig ileum.

Acetylcholine↗
PubMed1986

Prophylaxis of thromboembolic disease and platelet-related changes following total hip replacement: a comparative study of aspirin and heparin-dihydroergotamine.

A prospective study involving 120 consecutive patients undergoing total hip replacement was performed to compare the effectiveness of aspirin (high and low dose) or a combination of heparin plus dihydroergotamine (heparin-DHE) in preventing isotopic and phlebographic deep vein thrombosis (DVT), and to evaluate their effect on postoperative platelet changes. Phlebographic DVT was demonstrated in 9 cases (30%) in control group, in 1 (3.3%) in aspirin (high-dose) group (p less than 0.01), in 1 (3.3%) in aspirin (low-dose) group (p less than 0.01) and in 5 (16.6%) in heparin-DHE group (p = NS). Aspirin was able to reduce the postoperative increase in circulating platelet aggregates, platelet factor 4 and beta-thromboglobulin observed in control group. This study shows that aspirin is effective in the prevention of DVT for patients undergoing total hip replacement. Small aspirin dose (250 mg/day) represents an effective form of prophylaxis in these patients.

Aspirin↗
PubMed1985

Postoperative changes in the plasmatic levels of tissue-type plasminogen activator and its fast-acting inhibitor--relationship to deep vein thrombosis and influence of prophylaxis.

Fibrinogen, euglobulin lysis time (ELT), tissue-type plasminogen activator (t-PA) antigen, plasminogen activator inhibitor activity (PA-inhibitor) and alpha 2-antiplasmin (alpha 2-AP) were measured pre- and postoperatively in 60 patients undergoing total hip replacement. Reduced fibrinolytic activity as assessed by the prolongation of euglobulin lysis time, decrease of t-PA and increase of PA-inhibitor and alpha 2-AP could be demonstrated. These changes did not correlate with the postoperative deep vein thrombosis (DVT) diagnosed with the 125I-fibrinogen test. However, preoperative PA-inhibitor activity was significantly higher in patients with postoperative DVT (p less than 0.01). The prophylactic treatment with aspirin (20 patients) and with heparin plus dihydroergotamine (20 patients) induced significant changes in some of those parameters. This study shows that the decrease of t-PA and the increase of PA-inhibitor may contribute to the reduced postoperative fibrinolytic activity after total hip replacement. PA-inhibitor level might be a useful marker in evaluating the risk of developing DVT in patients undergoing total hip replacement.

Aspirin↗