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Biomedical subjects

G Colombo

Publications and source records attributed to G Colombo.

At least 163 records · Page 9Linked to original sources
PubMed1988

Pharmacokinetics of benperidol in volunteers after oral administration.

Benperidol in a 4 mg single dose was administered orally to five healthy male volunteers. The drug was rapidly absorbed (tmax = 2.27 +/- 0.57 h) and largely distributed, the volume of distribution being 5.19 +/- 1.99 l.kg-1. Elimination half-life was 7.65 +/- 2.14 h. Urinary excretion represented only a minimal fraction of ingested dose (0.1 +/- 0.007%). Variability of the area under the curve makes a first-pass metabolism a reasonable possibility. Acute dystonias appeared in two subjects.

Administration, Oral↗
PubMed1987

Characterization of highly purified dopamine beta-hydroxylase.

A modified purification procedure has been developed for dopamine beta-hydroxylase isolated from bovine adrenal medulla. Catalase is included in the homogenization step starting with a suspension of either chromaffin granules or adrenal medulla tissue. With this precaution, the enzyme remains stable in the supernatant solution in preparation for the subsequent purification step involving concanavalin A-Sepharose chromatography. The homogeneous enzyme has a specific activity in the range of 60-70 mumol O2 consumed/min/mg. Using radiolabeled metal ion chelators, it was determined that several of the chelators remained tightly bound to the enzyme after removal of the copper leading to difficulties in establishing stoichiometry of enzyme-bound metal ions.

Adrenal Medulla↗
PubMed1987

Testis cytological structure, plasma sex steroids, and gonad cytosol free steroid receptors of heterologous gonadotropin (hCG)-stimulated silver eel, Anguilla anguilla L.

Complete testicular maturation was induced in silver eels, kept at 24 degrees in fresh water, by a single injection of 1000 I.U. of heterologous gonadotropin (hCG). Each week, for 4 weeks, some eels were examined for testis structural pattern, plasma sex steroids, and gonad cytosol steroid receptors. The first effect of the hCG was on the tubular organization of the testis, followed by spermatogenesis. Plasma androgens were not detectable in the untreated eels, whereas a peak was detected a week after in those treated with the injection and afterward a decline. Plasma progesterone and estradiol showed a peak 2 weeks after treatment. Untreated eel gonads showed a high content of cytosolic free estradiol receptors which disappeared in the hCG-treated ones, a peak of free progesterone receptors was found 1 week after injection. The results are discussed in relation to the differentiation and maturation of eels testes.

Anguilla↗
PubMed1987

Ethanol prevents stress-induced increase in cortical DOPAC: reversal by RO 15-4513.

Electric foot-shock increased DOPAC and decreased DA levels by about 70 and 20% respectively in the medial prefrontal cortex in rats. Pretreatment with diazepam (5 mg/kg IP) or ethanol (1.2 g/kg orally) prevented these stress-induced changes. The protective effect of diazepam and ethanol was eliminated by RO 15-4513 (5 mg/kg IP) a partial inverse benzodiazepine agonist.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Electrochemical detection of benperidol in serum for drug monitoring in humans.

A high-pressure liquid chromatographic (HPLC) method for the serum assay of benperidol is described. One ml of serum is required for a single estimation. The method involves a simple and rapid extraction step (BondElut columns), HPLC separation (C8 10-mu column), and electrochemical detection (+0.65 V). Haloperidol is used as internal standard. On the basis of this procedure, recovery (93-97%) and reproducibility (intra-assay and inter-assay coefficients of variation less than 9%) are satisfactory. The detection limit is 0.2 ng/ml of serum. After therapeutic doses, trough serum levels ranged from 3.8 to 12 ng/ml in five patients.

Benperidol↗
PubMed1987

3-(1-Iminoethyl)-4,5-cycloalkylpyridine-2,6-diol derivatives. A novel class of benzodiazepine receptor antagonists and partial agonists.

A series of 3-(1-iminoethyl)-4,5-cycloalkylpyridine-2,6-diol derivatives have been prepared from isoxazolo [5,4-b] pyridones. Some of these compounds had affinity for the benzodiazepine receptors in vitro and in vivo radioligand displacement assays. These compounds did not have any anticonvulsant properties and were not active in pharmacological tests predictive of antianxiety activity, but antagonised the anticonvulsant and muscle-relaxant effects of diazepam and had proconvulsant properties.

Animals↗
PubMed1987

Technique for repeated collection of blood that has just perfused the pineal gland of sheep.

A long catheter was inserted into the superior sagittal sinus of sheep and was maneuvered to the level of the rectus sinus. The catheter was then secured to the head, neck, and shoulder of the animal. The distal end of the catheter was connected to a 3-way valve through which blood samples were collected and heparin was injected. Blood loss during surgery was minimal; recovery was quick and complete. The simple surgical technique enabled the collection of blood that has just perfused the pineal gland.

Animals↗
PubMed1987

Intravenous diltiazem in the treatment of unstable angina: a study of efficacy and tolerance.

Ten patients four men and six women aged 35 to 78 years (mean, 57) who had been admitted to a coronary care unit because of unstable angina, received intravenous infusions of diltiazem for three to ten days after a 24-hour observation period. During the observation and treatment periods, the patients were monitored daily for number of attacks of angina, nitroglycerin intake, blood pressure, and ECG parameters. Routine laboratory tests were performed before and after diltiazem therapy. Two patients did not respond to treatment, but administration of diltiazem controlled anginal pain in eight patients, without producing side effects. In one case the dose had to be reduced because of atrioventricular dissociation; in three cases there was a modest increase in SGPT. Diltiazem was found to be a safe and effective drug for controlling anginal attacks in patients with unstable angina.

Adult↗
PubMed1986

Amino acid sequence of Escherichia coli glutamine synthetase deduced from the DNA nucleotide sequence.

Glutamine synthetase is encoded by the glnA gene of Escherichia coli and catalyzes the formation of glutamine from ATP, glutamate, and ammonia. A 1922-base pair fragment from a cDNA containing the glnA structural gene for E. coli glutamine synthetase has been sequenced. An open reading frame of 1404 base pairs encodes a protein of 468 amino acid residues with a calculated molecular weight of 51,814. With few exceptions, the amino acid sequence deduced from the DNA sequence agreed very well with the amino acid sequences of several peptides reported previously. The secondary structure predicted for the E. coli enzyme has approximately 36% of the residues in alpha-helices which is in agreement with calculations of approximately 39% based on optical rotatory dispersion data. Comparison of the amino acid sequences of glutamine synthetase from E. coli (468 amino acids) and Anabaena (473 amino acids) (Turner, N. E., Robinson, S. T., and Haselkorn, R. (1983) Nature 306, 337-342) indicates that 260 amino acids are identical and 80 are of the same type (polar or nonpolar) when aligned for maximum homology. Several homologous regions of these two enzymes exist, including the sites of adenylylation and oxidative modification, but the regulation of each enzyme is different.

Amino Acid Sequence↗
PubMed1986

On the mode of action of a new contragestational agent (DL 111-IT).

Non-hormonal compounds belonging to 3,5-diphenyl-1H,1,2,4 triazoles and chemically related classes (triazoles in short) are known to be endowed with high contragestational activity in rodents, dogs and primates. The data herein reported for one of the leaders of this family of compounds (DL 111-IT) along with those previously reported for some analogues, demonstrate that triazoles cause pregnancy arrest by a direct action on conception product. This action is expressed through a progressive slowing down of the conceptus development with a consequent onset of a state of anoxia, pregnancy arrest, degeneration of placentae and adnexae and their absorption or expulsion. The selective time of gestation during which they elicit the antifertility effect (early post-implantation period) and the histological examinations revealed that the target of their action are the ectoplacental and decidual cells. Biochemical studies on conceptus product demonstrate that, although they do not bind to progesterone receptors or inhibit ornithine decarboxylase activity, triazoles induce an early and marked increase in the number of cytosol progesterone receptors accompanied by a steep decrease in the ornithine decarboxylase activity in the product of conception. These findings are discussed in relation to the possibility that triazoles may trigger pregnancy arrest by interfering with the chain of events by which progesterone regulates the mitotic activity of decidual and trophoblastic cells.

Abortifacient Agents, Nonsteroidal↗
PubMed1986

Evaluation of acute hemodynamic effects and pharmacokinetic behaviour of ibopamine in patients with severe heart failure.

The aim of the present investigation was to evaluate the acute hemodynamic effects of a single oral dose of 200 mg ibopamine (SB-7505), the 3,4-diisobutyryl ester of N-methyldopamine (epinine) in 11 patients with congestive heart failure (CHF) and to compare the influence of dopamine infusion and oral ibopamine on left ventricular function. Free and conjugated epinine plasma levels were also investigated in these patients and in a group of healthy volunteers to evaluate the correlation between epinine plasma levels and hemodynamic effects. The oral administration of 200 mg ibopamine to patients with CHF, increased cardiac index (+35%) and reduced peripheral and pulmonary vascular resistance (-29% and -26%) without modifying heart rate and systemic or pulmonary arterial pressure. The hemodynamic effect reached its maximum at about 90 min and was still present at 240 min. Ibopamine at a dose of 200 mg elicited similar effects to those observed with dopamine, 2-4 micrograms/kg/min. The pharmacokinetic behaviour of ibopamine in these patients was similar to that observed in a group of healthy volunteers. Free epinine plasma levels peaked at 30-60 min and decreased rapidly, thus showing a shorter time course than the hemodynamic effects.

Adult↗