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Biomedical subjects

A Olteanu

Publications and source records attributed to A Olteanu.

16 recordsLinked to original sources
PubMed2001

Solvent-induced collapse of alpha-synuclein and acid-denatured cytochrome c.

The effects of solution conditions on protein collapse were studied by measuring the hydrodynamic radii of two unfolded proteins, alpha-synuclein and acid-denatured ferricytochrome c, in dilute solution and in 1 M glucose. The radius of alpha-synuclein in dilute solution is less than that predicted for a highly denatured state, and adding 1 M glucose causes further collapse. Circular dichroic data show that alpha-synuclein lacks organized structure in both dilute solution and 1 M glucose. On the other hand, the radius of acid-denatured cytochrome c in dilute solution is consistent with that of a highly denatured state, and 1 M glucose induces collapse to the size and structure of native cytochrome c. Taken together, these data show that alpha-synuclein, a natively unfolded protein, is collapsed even in dilute solution, but lacks structure.

Circular Dichroism↗
PubMed1988

Changes of phagocytic biological rhythm by reduction of circadian times and by influences upon hypothalamus.

The circadian oscillations of central temperature and phagocytic activity of blood polymorphonuclears were studied in guinea pigs after circadian times have been reduced, under the effect of chlorpromazine or in animals with bilaterally lesioned hypothalamus in preoptic or in tuberomammillary area. The phagocytic activity was assayed against staphylococcus epidermidis in heparinized blood. In the animals exposed to artificial light in conditions of space restriction (stressed) the phagocytic activity is depressed in the lighting period, the differences light-dark being higher (300%) as in controls (25%). Chlorpromazine lowers both central temperature and phagocytic activity, without changes of their circadian rhythms. Bilateral symmetrical injuries of the preoptic hypothalamic area determined a rise of the central body temperature in the beginning of the dark period. The phagocytic activity of these animals decreases especially at the end of the dark period. Lesions of the tuberomammillary area reduces the phagocytic activity to very low levels and attenuates to a marked extent its circadian oscillations. Body temperature remain unaffected. The circadian biorhythm of the body temperature and of the phagocytic activity, usually concurrently, are controlled by separate hypothalamic mechanisms. After tuberomammillary lesions the phagocytic response of animals to an endovenous injection of a bacterial suspension is very low. The results are discussed on the basis of present data and of prior researches of this laboratory.

Animals↗
PubMedDate not supplied

Phagocytic response in rats following chemical sympathectomy with 6-hydroxydopamine.

Wistar rats were injected i.p. at 2, 4 and 7 days after birth with 6-OHDA (50 mg/kg). At maturity the phagocytic response of neutrophils was elicited by Escherichia coli (EC) lipopolysaccharide (LPS). Before and at 3 and 24 hours after the injection of LPS (1 mg/kg i.v.) the leucocyte (L) and neutrophil (N) counts and the phagocytic activity of N in blood against EC have been tested. In controls (6 female and 7 male rats) the number of N increases significantly after 3 h. The L and N responses were similar in controls and in treated (SyX) animals. In controls the percentage of phagocytic active N(PA) and the number of bacteria incorporated by 100 n(IB) shows significant rises at 3 h. In the SyX groups (7 females and 7 males) PA does not increase; the IB decreases significantly in females at 3 and 24 h. In conclusion chemical sympathectomy depresses the PR to LPS in rats; this suggests a stimulatory action of the sympathetic system on the phagocytic immune reaction. An immunological sexual dimorphism exists.

Animals↗
PubMedDate not supplied

[Surveillance of ventilation functions in collectives occupationally exposed to the risk of COPD].

The paper presents the clinical-functional manifestations in a group of 321 workers in a carbide department of a chemical combine works, professionally exposed to powders (calcium oxide, coke dust) and irritant gases (sulphur oxides, nitrogen oxides and ozone). Data processing, recorded on a questionnaire recommended by BMRC showed an incidence of 6.8% for simple chronic bronchitis, 14% for COPD and 39.8% for the disease of the small airways. The authors support the idea of the increased efficiency of the MEF50 test in comparison with MEVS for functional surveillance and early detection of broncho-obstructive ventilatory disturbances. In agreement with other dynamical observations of the authors the subjects found to suffer from simple chronic bronchitis have, in fact, obstruction, detectable by the MEF50 test.

Air Pollutants, Occupational↗
PubMedDate not supplied

The renin-angiotensin system and the effect of propranolol upon the cerebral cortical and hypothalamic circulation in hypoxia.

The regulatory mechanisms of the cerebral blood flow have preoccupied the physiology department of Cluj since the end of the 4th decade. These studies continued over the last years. The researches progressed from the studies of regulation by blood pressure changes to the nervous regulation and to the metabolic one. This paper's subject is the renin-angiotensin and adrenalin system influence on the changes of cerebral blood flow during the general hypoxic hypoxia and cephalic ischemia. Experiments were performed in 10 dogs anaesthetised with a mixture of chloralose, urethan and morphine. Hypoxic hypoxia was obtained by breathing a mixture of 11% oxygen in nitrogen, in a closed system and cerebral ischemic hypoxia by partial compression of the carotid arteries, after the ligation of the vertebral and thyroid arteries. The arterial blood pressure and the cerebral and hypothalamic blood flow, measured with the heated thermoelement, were registered. The plasma renin activity was tested radioimmunologically before, at 1.5 min, 5, 10 and 15 min, after the beginning of hypoxia. In ischemic hypoxia the experiment was repeated after venous perfusion with propranolol (0.6 mg/kg/h). The systemic blood pressure increased in both forms of hypoxia. The cortical and hypothalamic blood flow increased with the systemic arterial blood pressure. The hypothalamic blood flow remained stable or diminished a little. Propranolol increased the cerebral blood flow during ischemic hypoxia up to 300%. The i.v. administration of angiotensin (1-5 mg/kg) increased the cortical flow, while the hypothalamic flow remained self-regulated. Plasma renin activity increased more in general hypoxic hypoxia, than in cephalic ischemic hypoxia. After propranolol the increase was higher in this hypoxia. Propranolol produced a major activation of the renin-angiotensin system and of the cortical blood flow in ischemic cephalic hypoxia, the renin-angiotensin system being located in the cerebral structure. As well high doses of angiotensin produced cerebral vasodilatation in small cerebral vessels. This effect was found in our experiments in the cortical blood flow too. Our results indicate a beneficial propranolol effect on cortical circulation in ischemic hypoxia.

Animals↗