Physico-chemical and immunological properties of bovine liver 5'-deoxy-5'-methylthioadenosine phosphorylase.
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Biomedical subjects
Publications and source records attributed to R Palumbo.
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Five healthy male volunteers received over 60 sec a single intravenous injection of 400 mg of teicoplanin labelled with 41 microCi of 14C. Plasma and urine total radioactivity was measured up to 10 and 16 days, respectively. Teicoplanin was assayed in plasma and urine also by a microbiological method, with similar results. Pharmacokinetic parameters were estimated by model-independent analysis and the following mean values were obtained: elimination half-life 77 h; total body clearance 9.8 ml/h/kg; renal clearance 7.81 ml/h/kg; volume of distribution at steady-state 0.759 l/kg. Similar estimates were obtained by a compartmental analysis. A total of 80% of the administered dose was recovered in urine in 16 days; 2.7% of the dose was recovered in faeces collected for eight days after administration. The mean total recovery of the drug was 83 +/- 0.6%. The plasma and urine concentrations of teicoplanin observed after a single 400 mg iv dose exceeded the MIC for most pathogens for at least one day, and this suggests that a daily dosage regimen would be satisfactory for patients with normal renal function.
Clearance of inhaled 99mTechnetium-labelled diethylene triamine pentacetate (99mTc-DTPA) from the lung, an index of pulmonary alveolar epithelial permeability (PAEP), was measured in 13 patients with cardiogenic interstitial pulmonary oedema (CIPO) and in 7 patients with adult respiratory distress syndrome (ARDS). Thirty-five normal subjects (22 nonsmokers and 13 smokers) were evaluated as controls. Half-time clearance (t0.5) values in ARDS patients (mean +/- SD: 15 +/- 2 min) were significantly lower than in CIPO patients (62 +/- 9 min). This PAEP increase in ARDS was impressive, even in comparison to heavy smokers. Loss of the PAEP vertical gradient (apical PAEP greater than base PAEP) was observed in both cardiogenic and ARDS lungs and among smokers.
This study was undertaken to evaluate (1) the colonic response to eating for a prolonged time in healthy subjects and patients with the irritable bowel syndrome (IBS); (2) the effect of octylonium bromide, a new smooth muscle relaxant acting by interfering with calcium ion mobilization, on the postprandial colonic motility; and (3) whether chronic gastric stasis could be responsible for both the dyspeptic symptoms often complained of by IBS patients and the faulty colonic response to eating. The colonic response to a 1000-kcal mixed meal in ten healthy subjects was characterized by two transient (from 0 to 60 and from 120 to 150 min postprandially, respectively) increases in colonic motor activity; ten IBS patients showed a continuous postprandial increase in colonic motor activity that was not terminated 180 min after eating. Treatment of IBS patients with octylonium bromide (80 mg, qid, per os) for 5-7 days reduced their colonic response to eating to a very short increase in colonic motor activity limited to the first 30 min. Finally, gastric emptying was not different in the two groups.
Chronic idiopathic gastric stasis can be responsible for unexplained dyspepsia. Because exogenous opiates inhibit gastric emptying and endogenouslike substances are present in the gastrointestinal tract, we tested the hypothesis that increased endogenous opiate activity may be responsible for chronic idiopathic gastric stasis. Eighteen patients with chronic idiopathic gastric stasis and ten healthy volunteers were studied by gastrointestinal manometry. Scintigraphic technique also was used, during which either intravenous saline or naloxone hydrochloride were infused. Manometry showed gastric hypomotility in ten patients and duodenal hyperdyskinesia in the remaining eight patients. Naloxone did not alter gastric emptying in healthy subjects or corrected gastric stasis in patients with gastric hypomotility, while it normalized gastric emptying in patients with duodenal dyskinesia. It seems that either gastroparesis or duodenal dyskinesia can promote gastric stasis and chronic dyspepsia, and endogenous opiates participate in the pathogenesis of gastric stasis in patients with duodenal dyskinesia.
There is significant evidence that in the general population there are subjects either with fast or slow pulmonary mucociliary clearance rates. At the moment we do not know the physiological importance of such finding. Slow clearers should be regarded as a subpopulation at risk for bronchopulmonary diseases. Therefore, it would be of considerable interest if their mucociliary function could be stimulated by drugs for preventive purposes. Twelve apparently healthy subjects with slow mucociliary clearance rate, selected in an epidemiologic survey in a non-smokers population were given 0.6 g oral N-acetylcysteine/day/60 days in a double-blind cross-over randomized study. After treatment their mucociliary clearance rates increased by about 35% as compared with baseline values, and returned to pre-treatment values after the washout period. Subjects were unresponsive to placebo treatment. It would seem that slow clearers are protected against lung aggressions by prevention and/or mucus-active drugs.
Premazepam, a pyrrolodiazepine with potential anxiolytic properties, behaves as a partial antagonist to diazepam in animal tests. Its pharmacokinetics and metabolism were studied in four healthy volunteers. After oral administration of 30 mg [6-14C] premazepam, the plasma levels of total radioactivity reached maximum concentrations 1-4 h (mean 2 h) following administration. The plasma curve was described by an open one-compartment model, and half-life was 11.5 +/- 1.3 h. Levels of the unchanged compound accounted for about 80% of the total radioactivity up to 24 h. Half-life of the unchanged compound was 7.9 +/- 1.2 h. On the average, 89.6% of the administered radioactivity was recovered in the urine and 2.3% in the feces during the 5 days following administration. Unchanged premazepam accounted for about 70% of the total radioactivity excreted in the urine. Of the three metabolites identified in the urine, none was active in vitro in displacing 3H-diazepam from its forebrain receptors in the rat, indicating that only the parent compound has definite pharmacologic activity.
The authors set up a simple and fairly rapid radioimmunoassay for vincristine, that shows a good sensitivity, precision and specificity. In particular, the higher specificity in comparison with other similar dosage techniques is likely due to the marked specificity of the used anti-vincristine serum, which displays a low interference even by molecules with a vincristine-like structure. Therefore, the suggested radioimmunoassay technique seems quite suitable for studying vincristine pharmacokinetics and for monitoring blood levels of this alkaloid in treated patients.
A subliminal psychodynamic activation experiment was conducted in which the effects of five subliminal stimuli were sought on the dart-throwing performance of male subjects. The stimuli consisted of the following messages, each accompanied by a congruent picture: BEATING DAD IS OK, BEATING DAD IS WRONG, BEATING HIM IS OK, BEATING HIM IS WRONG, and PEOPLE ARE WALKING. The first two stimuli were intended to activate competitive motives within the context of the Oedipus complex; the next two, competitive motives outside that context; and the last was intended as a control stimulus. BEATING DAD IS OK led to greater dart-throwing accuracy than each of the other four conditions, which in turn did not differ from each other. This finding replicated a result reported by Silverman, L. H., Ross, D., Adler, J., and Lustig, D. (J. Abnorm. Psychol., 87: 341-357, 1978) and is in keeping with the formulation that the activation of oedipal motives can affect competitive performance. Neither a subject variable (fear of success) nor the differential effects of two experimenters was found to interact with stimulus conditions in affecting dart scores.
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To study mucociliary clearance of central airways we used a recently described method consisting of the inhalation of 99mTc labeled autologous spherocytes aerosol. In 3 of 8 normal non smoking subjects, an abnormally low rate of m.c.c. was observed. The m.c.c. rate was also very low in 2 of 6 patients with bronchial cr. who never smoked. These observations provide considerable evidence that those non smoking subjects presenting with low mucociliary clearance may be regarded as "high risk subjects" for broncho-pulmonary diseases. The good central deposition pattern of the inhaled spherocytes may provide, in very ill patients, a non-invasive visualization of the central airways.
To investigate the site and mode of action of progesterone in inducing gonadotropin release, the effects of catecholamine-depleting (methyldopa) or dopamine agonist (bromocriptine) drugs on progesterone positive feedback and the gonadotropin response to a centrally acting noradrenergic drug (clonidine) were evaluated in estrogen-primed postmenopausal women. Progesterone administration induced a significant rise in LH, FSH, and PRL serum levels in the control group. Bromocriptine administration was followed by a marked suppression of PRL release but did not modify the gonadotropin response to progesterone. Methyldopa pretreatment significantly reduced the progesterone-induced LH surge, while PRL release was unaffected. After estrogen priming, clonidine administration did not result in an increase in serum LH or FSH concentrations. The dissociated responses of LH and PRL in bromocriptine-pretreated subjects and the significant reduction of the LH rise after progesterone in methyldopa-pretreated women seem to invalidate the hypothesis that a fall in endogenous dopamine is responsible for progesterone positive feedback and suggest that neural noradrenergic mechanisms are involved in progesterone-induced gonadotropin release. The ineffectiveness of a centrally acting noradrenergic agonist in inducing gonadotropin rise provides indirect evidence that an increased pituitary responsiveness may also be involved in progesterone positive feedback.
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