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Biomedical subjects

A Colombi

Publications and source records attributed to A Colombi.

At least 73 records · Page 4Linked to original sources
PubMed1977

Metabolism of quaternary carbon compounds: 2,2-dimethylheptane and tertbutylbenzene.

Two Achromobacter strains capable of utilizing 2,2-dimethylheptane or tertbutylbenzene as the sole carbon and energy source were isolated from waste-water. Pivalic acid was found in the cultures of Achromobacter A1 containing 2,2-dimethylheptane. From cultures of Achromobacter A2 in the presence of tertbutylbenzene, a diol was isolated and identified as 2,3-dihydro-2,3-dihydroxytertbutylbenzene. Evidence for meta cleavage of the aromatic ring and for accumulation of pivalic acid in the cultures was also obtained. A metabolic pathway for tertbutylbenzene is suggested.

Alcaligenes↗
PubMed1976

[Peritoneal dialysis, ultrafiltration and hyperosmolarity].

Observation of a patient who developed serious hypernatremia during peritoneal dialysis with a dialysis fluid containing 135 mval Na+/1 prompted investigation of net water, sodium, potassium and chloride transport during 45 peritoneal fluid exchanges with standard dialysis solutions containing 1.5 and 4.5 g% glucose. With both solutions and an equilibration time of 0 min, net ultrafiltration was observed (89 ml and 230 ml per exchange respectively). In both groups the calculated sodium concentration of the ultrafiltrate was considerably lower than plasma sodium concentrations (27.0 mval/1 and 36.9 mval/1 respectively, resulting in a new sieving coefficient of 0.20 and 0.27 respectively. Therefore, the free water deficit resulting from peritoneal ultrafiltration is directly responsible for the hypernatremia observed during peritoneal dislysis. While the potassium and chloride transport observed in these studies can be explained by diffusion processes along a given concentration gradient, sodium transport and sodium concentrations raise the question of more complex mechanisms. The data are discussed with reference to the relative significance of diffusion processes versus bulk flow and solvent drag.

Biological Transport↗
PubMed1976

An electrophysiological investigation of skeletal muscles in polymyositis.

An electrophysiological study has been made of the extensor digitorum brevis, thenar and hypothenar muscles in 25 patients with chronic and acute polymyositis. It was found a reduction of the number of functioning motor units in some patients with chronic polymyositis and only in one of those affected by acute polymyositis and only in one of those affected by acute polymyositis. The sizes of the surviving units suggested that the results could be explained in terms of a primary muscle involvement mainly in acute polymyositis, while in chronic polymyositis a combination of primary and neurogenic involvement of muscle fibers might take place.

Acute Disease↗
PubMed1975

Hypotensive effect of oxprenolol in mild to moderate hypertension: a multicentre controlled study.

In a multicentre, double-blind, between-patient study the hypotensive effect of oxprenolol was investigated in 329 patients with mild to moderate hypertension. A factorial experimental design with three factors was chosen: oxprenolol--none or daily doses of 20, 40, 60 and 80 mg; dihydralazine and hydrochlorothiazide, respectively, none or 30 mg daily. Each treatment was given for 4 weeks after an adequate period of withdrawal from any other possible hypotensive therapy and one week of placebo wash-out. Irresponsive of the association with dihydralazine and/or hydrochlorothiazide, oxprenolol had a hypotensive effect linearly related to dose for standing systolic (P less than 0.05) and diastolic (P less than 0.01) pressure, and for lying diastolic (P less than 0.05) pressure. The additional of dihydralazine enhanced the time-course of the hypotensive effect of oxprenolol, particularly the 80 mg dose level. In general, the combination of oxprenolol with dihydralazine and hydrochlorothiazide caused larger reductions in blood pressure, particularly with oxprenolol 80 mg. In the latter group, the eventual falls in blood pressure were 30.5 and 14.4 mmHg for lying systolic and diastolic, respectively; and 32.1 and 20.0 mmHg for the standing systolic and diastolic pressures. The drug was well tolerated; major side effects (heart failure and bronchospasm) occurred in three patients.

Clinical Trials as Topic↗
PubMed1975

[Electrophysiology in neuropathy caused by vincristine].

Ten patients treated with vincristine were submitted for electrophysiological examination. It was investigated the number of motor units within the thenar muscle following a technique described previously (Sica et al. - 1974); motor and sensitive conduction velocities as well as motor distal latencies in the median nerve were studied following conventional techniques. The behaviour of the evoked muscle potential with repetitive supramaximal stimulation over the median nerve was also investigated. The findings were compared with control groups. The estimated number of motor units was disminished in eight of ten patients and the average number was significantly different from the control group (control 318 +/- 71 UM; patients 174 +/- 84 UM; P less than 0.001). The potential amplitudes in most of the surviving units were reduced, others remaining within the normal range. This makes apparent that the peripherical nervous system fails to compensate adequately and, furthermore, a loss of individual muscle fibres occurs within some individual units. The conduction velocities of the fastest conducting motor nerve fibres were reduced and motor distal latencies prolongued (Table 1). Maximal impulse conduction velocities were measured in sensory fibres. In 5 of 7 subjets investigated the values laied just beyond the lower limit of the normal range. The amplitude of the sensory orthodromic evoked potential in the median nerve at the wrist was disminished almost in the whole group. The decremental muscle response to repetitive nerve stimulation, can be interpreted as the result of the damage at the neural apparatus at the motor end plate; it was observed in 57% of the patients. In summary, evidences have been registered showing that the nervous supply to the muscle is affected in patients treated with vincristine; the motor unit behaviour under this conditions is discussed.

Adult↗
PubMed1973

Metabolism of biphenyl. 2-Hydroxy-6-oxo-6-phenylhexa-2,4-dienoate: the meta-cleavage product from 2,3-dihydroxybiphenyl by Pseudomonas putida.

1. 2-Hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid was isolated and identified from washed suspensions of Pseudomonas putida incubated in the presence of 2,3-dihydroxybiphenyl. 2. Benzoic acid was isolated from reaction mixtures of crude cell-free extracts incubated with 2,3-dihydroxybiphenyl. 3. The presence in the same reaction mixtures of either 4-hydroxy-2-oxovalerate or 2-hydroxypenta-2,4-dienoate was suggested by mass spectrometry. 4. The degradative pathway of biphenyl is discussed.

Benzoates↗