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Biomedical subjects

I Baciu

Publications and source records attributed to I Baciu.

71 records · Page 4Linked to original sources
PubMedDate not supplied

The role of hypothalamic centres in the immune specific response.

Four groups of rats were bilaterally lesioned in the anterior, lateral, tuberal and mammillary areas of hypothalamus. Seven days later these rats, as well as controls, were immunized concomitantly with three antigens: Salmonella enteritidis, sheep red blood cells and Myxovirus influenzae A (H3N2). The primary and the secondary response were tested. The bacterial and erythrocytic antigens, with marked immunogenetic capacity, produced immune responses, which were not significantly influenced by hypothalamic lesions. The immune primary and secondary response to influenza A virus is wholly suppressed in animals with lesions in tuberal and mammillary areas of the hypothalamus. It is reduced in animals with lesions in lateral and anterior regions, as compared with controls. The secondary response is greater and more rapid in controls. It is reduced in animals with lesions in anterior and lateral hypothalamus and suppressed in those with lesions at tuberal and mammillary level. It therefore seems that the modulatory intervention of the hypothalamus in the immune process depends on the antigen, on the antigen, on the intensity of its direct effects on the immuno-competent and accessory cells and on the condition of the hypothalamic centers.

Animals↗
PubMedDate not supplied

Action of 6-hydroxydopamine on two parameters of motor learning.

In rats injected in the cerebral ventricle with 250 micrograms of 6-hydroxydopamine a significant blockade of the improvement of swimming performance due to training occurs. The central injection of 6-OHDA leads to a lengthening of the total latency time (LT) of active conditioned reaction in shuttle box and of the LT of netative escape responses during learning, but not of the positive avoidance responses. 6-OHDA injected after the learing schedule (12 days) has no effect on the LT during relearning and extinction. Therefore a partial destruction of central monoaminergic, and especially of dopaminergic, neurons impairs particularly the acquisition but not the retention of the motor program.

Animals↗
PubMedDate not supplied

Reticulin-M, an antianaphylactic peptide secreted by reticulo-endothelial system.

I. Moldovan (1923) demonstrated in the blood ultrafiltrate from anaphylactically prepared guinea pigs, which believed to anaphylactic shock, or which were previously injected with coloidal substances as India ink to stimulate the RES, an antianaphylactic principle named Reticulin-M(R). Authors extracted R from organs rich in RES with acetone, established their, peptidic nature and tested it on anaphylactic prepared guinea pig uterine horns in vitro. The peptides were fractioned by high voltage paper electrophoresis. The fractions were cut up in four groups, eluted and tested. The second basic group was identified as active and concentrated by acetone, recipitation. In conclusion several techniques were used to obtain, to test, to isolate and to concentrate R, a natural antianaphylactic peptidic factor, which may be a cytokine.

Anaphylaxis↗
PubMedDate not supplied

The influence of moderate hyperbaric environment on the sensory-neuro-motor processes in man.

Thirteen healthy male divers were repeatedly studied during the exposure to a moderate hyperbaric environment of 4--6, 7 and 9 ATA, in a hyperbaric chamber. The maximal duration of the exposure was 35 min, and that of decompression 90 min. As compared to the dynamics of the changes found in 14 controls, under hyperbaric conditions a significant increase in the number of static tremor, an impairment of the sensory-motor performance in O'Connor's and in the rotation test were found and also of the muscular strength and resistance to fatigue (this latter only at 9 ATA).

Adult↗
PubMedDate not supplied

The influence of moderate hyperbaric environment on some nervous functions and on the sympatho-adrenal and adreno-cortical activity in man.

Thirteen healthy males were repeatedly studied during the exposure to a moderate hyperbaric environment of 4--6, 7 and 9 ATA, in a hyperbaric chamber and partly during immersion in sea water (3.5--4 ATA). The maximal duration of the exposure was 35 min and that of decompression 90 min. As compared to the dynamics of the change found in controls, under hyperbaric conditions a significant prolongation of the visual reaction time (especially during sea dives), and an impairment of the mental performance in an arithemetical calculation test were found. There occurs an increase of the excretion in urine of cortisol, epinephrine and vanillylmandelic acid, especially after immersion in sea.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Integrative cybernetic model of oxygen homeostasis.

The paper presents an integrative cybernetic model of the complex physiological process generically called "oxygen homeostasis". The model has been designed in such a manner as to enable a mathematical approach, in quantitative terms, to the various functions involved in the generation and uninterrupted functioning of the mentioned process. Those functions are: pulmonary and tissular respiratory function, blood circulation, transport, erythropoiesis, as well as other functions involved in the blood pH regulation at renal and hepatic level (the resorption of Na+ ions from the glomerular filtrate and the ammonio-genetic functions of the kidneys and, respectively, the glyco-genetic, ureo-genetic and metabolization functions of the liver). All of these functions have been assumed as regulated and controlled within a unitary cybernetic system, interpreted as an open, dynamic system. That system consists of seven multicompartment subsystems which are open and interconnected by means of exchange relations, biophysical and biochemical processes involved in the performance of the respective function. Special attention was given to the mathematical modelling of the exchange processes going on in the erythrocytic membrane as part of the transport function of the circulating blood. The mathematical description of the entire homeostatic system operation was done by means of a set of differential and algebraic equations. Some of those equations (those describing the continuity of several chemical species in a compartment of the circulatory system and those characterizing the state of thermodynamic balance of the blood subsystem within the respective compartment) enable one to determine the value of the state parameters at a given moment, as a function of the external and internal conditions and as a function of the intensity of processes specific to the subsystems considered. There are other equations (equations of regulation and control devices) that enable one to determine the variations in intensity of the processes mentioned that are necessary in order to restore the system to its "normal" state, in case of possible deregulations caused by disturbing factors.

Animals↗
PubMedDate not supplied

The effects of electroconvulsant shocks on phagocytic activity and on phagocytic response.

The influence of a single or several subsequent convulsant electroshocks at different time laps (2-4 day), over a month, on the phagocytic activity was studied on seven dogs. The electroconvulsant shock was performed with bitemporal electrodes, at a liminal electric power. Phagocytosis was studied in vitro with amidon particles in whole blood, incubated 1h at 37 degrees C. After 4 hours the phagocytosis increases in all animals and remains higher for 12 days. Later on the repeated shocks produce very different changes of the phagocytic activity, depending, not only on the stressor agent, but also on the animal particular reactivity, conditioned genetically and by its individual history.

Animals↗
PubMedDate not supplied

Effects of thymectomy on blood neutrophils phagocytic activity and phagocytic response in mice.

The role of the thymus in maintenance of the basal phagocytosis of blood neutrophils and eliciting the phagocytic response, induced by i.v. Escherichia coli, was studied in 9 NMRI thymectomized and in 12 control mice. Thymectomy depresses the percentage of phagocyting neutrophils from 70.91 +/- 0.9 (mean +/- SEM) in controls, to 61.49 +/- 2.33 in the thymectomized rats. Phagocytic activity, as assessed by the number of bacteria engulfed by 100 neutrophils, was also lower in thymectomized mice (114.42 +/- 7.52) than in controls (163.71 +/- 4.53). A phagocytic response to i.v. Escherichia coli could nevertheless be noted in thymectomized mice, their phagocytic activity rising from the basal activity of 114.42 +/- 7.52 to 142.19 +/- 5.40 three hours after injection of Escherichia coli, while in control animals this activity rose from 163.71 +/- 4.53 to 216.46 +/- 12.91. These results may, at least partially, explain the recurrent infections and the septicemia occurring in children with Down's syndrome. It is suggested that the thymus, as an endocrine organ, may be involved in maintaining the basal phagocytic activity of blood neutrophils, while the phagocytic response is modulated by extrathymic mechanisms.

Animals↗
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↗
PubMedDate not supplied

Effects of electrolytic bilateral symmetric lesions of the arcuate nucleus on the phagocytic activity and on the phagocytic response in rats.

Previous researches of Cluj-Napoca laboratories of Physiology (Benetato, Baciu et al., 1945, 1946, 1947) demonstrated that direct electrical stimulation of the tubero-mammillary area in dogs increases, in the following hours, the blood polymorphonuclears phagocytic activity. By contrast, electrical damage of the same region produces a depression of the basal phagocytic activity and a blocking of the phagocytic response (Baciu et al., 1958, 1988). In the present research we assumed there is a stimulating effect of the arcuate nucleus, located in this area, on the phagocytic activity of blood neutrophils. We used an anodal current to stereotaxically induce lesion of the arcuate nucleus in six rats. A control group of six animals was used. Five days later, phagocytic response was induced with a Gram negative bacterial extract given i.v. The results demonstrated a decrease of the phagocytic activity from 164.31 +/- 17 bacteria engulfed by 100 neutrophils in controls, to 138 +/- 12.8 in the lesioned group p < 0.05. Phagocytic response after five hours appears depressed in the lesioned group (138 +/- 12.8 to 156.25 +/- 13.3, p < 0.05). Similar results were obtained after 24 hours. In control animals the response is very significant after 5 and 24 hrs., respectively, (p < 0.001). In conclusion, the arcuate nucleus is moderately involved in sustaining the basal phagocytic activity of blood neutrophils. It has an important role in phagocytic response.

Adjuvants, Immunologic↗
PubMedDate not supplied

Effects of monosodium glutamate on blood neutrophils phagocytic activity and phagocytic response in mice.

Previous researches of our laboratories (1945, 1946, 1947) have shown that direct electrical stimulation of the tubero-mammillary hypothalamic area in dogs enhances the blood neutrophils phagocytic activity and the phagocytosis exhibiting leukocytes percent. After electrolytic damage of the same area, phagocytic activity decreases and phagocytic response is suppressed (1985, 1988). In the present work, we performed in mice extensive chemical lesions of the arcuate nucleus, by means of the neonatal treatment with monosodium glutamate (MSG). The experiment was carried out on 23 new-born mice. 15 mice were injected with MSG (G group), the other 8, serving as control group, received isotonic saline solution (C group). The studied parameters were, in both groups, the weight evolution of the animals, the blood neutrophils and lymphocytes percentual variation and the neutrophils' phagocytic activity, tested in vitro, expressed through the number of bacteria engulfed by 100 neutrophils and through the phagocyting neutrophils percentage. Phagocytic activity was tested in whole heparinised blood, against E. coli. Phagocytic response was elicited by i.p. injecting 0.05 ml bacterial suspension and was tested four hours later. The results show that the arcuate nucleus has little influence upon maintaining basal phagocytic activity--that does not significantly decrease after its chemical damage--, but plays a decisive role in triggering the phagocytic response. The neonatal MSG treatment also determines a decrease of the blood lymphocytes percentage and induces obesity in up to 30 days old mice pups.

Animals↗