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Biomedical subjects

P G Data

Publications and source records attributed to P G Data.

At least 19 recordsLinked to original sources
PubMed1994

Effect of acute and chronic cobalt administration on carotid body chemoreceptors responses.

Chronic cobalt exposure leads to release and production of erythropoietin and consequently to polycythemia. Accordingly, cellular elements sensitive to oxygen in the carotid body, would manifest responses during acute and chronic cobalt administration. The carotid body, detects gas changes (PO2, PCO2/pH) in the arterial blood and regulates ventilation and circulation by the afferent nerve discharge. We hypothesized that cobalt interacts with an oxygen sensitive mechanism in the carotid chemoreception and in erythropoietin producing cells. Twelve cats were anesthetized, paralysed and artificially ventilated; few fiber preparation of carotid sinus nerve were recorded during close intraarterial injection of cobalt. In another protocol, 12 rats received an intraperitoneal dose of CoCl2 (10 mg/kg) daily for 6 weeks. At the end, the carotid body was fixed in situ by superfusion. Ultrastructural and morphometric studies were made. Acute administration (0.08-2.3 mumol) promptly stimulated the chemoreceptor afferents. Type I cells increased significantly along with erythropoiesis in the chronic cobalt treated rats. The stimulatory effects of cobalt on the carotid body chemoreceptor showed that sensitive mechanisms in the kidney and in the carotid body are similar, and cobalt interacts with the physiological responses of oxygen.

Animals↗
PubMed1994

Potentiometric determination of carbonic anhydrase activity in rabbit carotid bodies: comparison among normoxic, hyperoxic and hypoxic animals.

The catalytic activity of carbonic anhydrase (CA) contained in the glomus cells of mammalian carotid bodies has been determined in vitro by a potentiometric method. Experiments performed on whole rabbit carotid bodies have shown a very low variability, in terms of the overall CA activity, among organs belonging to different animals maintained in normoxic conditions. Repeated assays performed on each carotid body have shown a marked decrease of the overall CA activity after the first assay, thus suggesting the presence of at least two different forms of enzyme. Experiments performed on carotid bodies belonging to rabbits maintained in normal, hyperoxic and hypoxic conditions have shown that the overall CA activity follows the sequence: hypoxic > normoxic > hyperoxic, matching with the corresponding physiological activity of the carotid body.

Animals↗
PubMed1992

Chemosensitivity and regulation of ventilation during sleep at high altitudes.

The paper presents new observations on young high altitude natives (Andes and Himalayas), testing the hypothesis that periodic breathing with apnea during sleep is determined by their ventilatory sensitivity to hypoxia and its interaction with the sleep state. The hypothesis is in general supported by the evidence. But, contrary to expectation, the ventilatory sensitivity to hypoxia in the Sherpa children was significantly lower than those in the Andes. Despite that departure, the magnitude of ventilatory periodicity among the subjects was internally consistent with their ventilatory sensitivity to hypoxia. Although the carotid chemosensory input is the pacesetter for the reflexive periodicity, mechanisms in the central nervous system can influence it significantly.

Adolescent↗
PubMed1991

Chronic cobalt causes hypertrophy of glomus cells in the rat carotid body.

We tested the hypothesis that chronic cobalt administration would induce carotid body cellular response along with polycythemia as found in chronic hypoxia if common oxygen-sensitive mechanisms were involved in the two instances. Morphometric studies were performed on carotid bodies in male rats that were chronically treated with cobalt chloride (0.17 mumol/kg, ip, daily for 6 wk) and in control rats that received blank saline injections. The rats were anesthetized, blood samples were collected for hematocrit, and the carotid bodies were surgically exposed and were perfused and superfused with the buffered fixative (3% glutaraldehyde plus 1% paraformaldehyde, pH 7.40, 330-340 mosM). The carotid bodies were processed, and ultrathin sections were cut for electron microscopy and morphometry of type I (glomus) and type II cells. Hematocrit increased from 44% in the control to 74% in the cobalt-treated rats, and the mean volume of type I cells increased from 424 to 1,061 microns 3. Type II cells did not show any significant change in size. The results suggest that cobalt stimulated oxygen-sensitive mechanism in the glomus cells of the carotid body and that the glomus cell is a site of oxygen chemosensing.

Animals↗
PubMed1990

Pulmonary blood flow distribution in erect man in air and during breathhold diving.

We used intravenously administered 99mTc-labelled macroaggregates and a gamma camera attached to a computer for measuring distribution of pulmonary blood flow per unit lung volume in eight healthy subjects sitting erect in air and also during breathhold diving to 1 or 10 m of depth. We measured distribution of perfusion in the supine position and substituted regional lung volume with regional perfusion in the supine for calculating regional perfusion per lung volume erect in air and during diving. The perfusion per unit lung increased rectilinearly down the lung in subjects below 30 years of age but decreased in the lowermost regions in older subjects. This decrease showed a strong correlation to closing capacity. An age-related decrease in transpulmonary pressure may influence both basal perfusion and closing capacity. During submersion, perfusion became equal in all regions with the exception of the lung apex which became hyperperfused. Close to the diaphragm, small inconsistent changes were noted. Redistribution was the same at surface (1 m of depth) with the lung volume being close to total lung capacity and at 10 m of depth when lung volume was compressed to functional residual capacity. During breathhold diving, high intrapulmonary blood volume and pressure became more important for blood flow distribution than gravity or lung volume, while differences in regional hypoxic vasoconstriction and in transpulmonary pressure seem to explain interindividual variation.

Adult↗
PubMed1988

Change in plasma amino acid concentrations during breath-hold diving at high altitude.

We studied the plasma concentration of various amino acids in 6 Italian sport divers in Italy and at approximately 4,500 m altitude in Peru; 6 Peruvian inhabitants were examined for comparison. We attempted to create a situation of pronounced hypoxia in muscles by breath-hold diving at altitude. The diving reflex diverts blood away from muscles while diving increases central oxygen tension and prevents loss of consciousness. Differences in certain amino acids, probably related to diet, were noted between Italy and Peru. Increases in concentration of plasma alanine and some branched-chain amino acids occurred after breath-hold diving. These changes were similar to those seen after prolonged hard exercise, even though physical work was low. Hypoxia in muscles, common during hard work and during breath-hold diving at altitude, might thus be the stimulus for amino acid release from working muscles.

Adult↗
PubMed1984

[Inappropriate gonadotropin secretion in the polycystic ovary syndrome].

In this study was investigated the diagnostic significance of double stimulation test with (that is of 25 micrograms rapid injection intravenously twice at an interval of 120 minutes and the misure of maximal net increment of serum LH after the first GnRH injection expressed as delta 1 and after the second injection, expressed as delta 2) to discriminate patients with idiopatic hirsutism. This test was effectuated on 8 patients with PCO (presence of polycystic ovaries on Ecografya and/or Laparoscopy) and 8 patients with idiopatic hirsutism (presence of normal morphology ovaries). Basal LH, FSH, E1, E2 and delta 4 levels were also measured. The value of LH delta 2 were more elevated in patients with PCO (p less than 0,0002) than the patients with idiopatic hirsutism. Consequently it as been value of LH delta 2 to discriminate the two different groups of patients. In PCO patients were also found: -a positive linear correlation between LH delta 1 and basal concentration serum of E2 (p less than 0,001); -a significant increase of basal levels serum of delta 4 (p less than 0,02); while the values of basal LH and LH delta 1 were found superior only on 4 of the initial 8 patients, the basal values of E1 and E2 were at the superior found of the norm and basal FSH, FSH delta 1 and FSH delta 2 values were found normals.

Diagnosis, Differential↗
PubMed1984

[Computerized system for the acquisition and analysis of bioelectric waves].

With collaboration of medicals, electronics and informatics; we have evaluated a method destined to be a potent instrument for the analysis and store of bioelectrical signal. The signal can be taken directly from the subjects or from a tape recorder; we can call again stored for evaluating the gradient grade, the integral and other mathematical evaluations of traits of a curves; in example EEG, EOG, PEV, etc.

Computers↗
PubMed1984

[Respiratory and cardiac activity during sleep at high altitude (4650 m. above sea level)].

In this study, the relationship between the cardiac rhythm and ventilatory rhythm, during the sleep, at high altitude (4560 s.l.- Peruvian Andes) has been evaluated in native acclimated, and long-term resident people. The experimental observation has been performed from 11.00 p.m. to 7.00 a m. (when the barometric pressure was 430 mmHg, pO2 was 90 mmHg and paO2 was 71 mmHg) by using an eight channel polygraph for EEG, usefully modified for ECG and pneumographic recordings. In agreement with the observations of other Authors, a periodic breathing was recorded when the theta rhythm (low amplitude waves, characteristic of the second stage of the sleep) appeared in the EEG. During the REM stage of the sleep, the respiration becomes irregular, without periodicity in the ventilatory rhythm. Any statistical difference was not observed between European and Andinian subjects. During the N-REM phases of the sleep, the cardiac activity was often clearly dissociated from respiratory cycles. This finding suggests that, during the 2 and 4 phases of the sleep, in our experimental conditions, the cardio-inhibitory and cardio-acceleratory centers seem to lose the correlation with the regulatory centers of the breathing.

Adult↗
PubMed1983

Cardiac output and gas exchange during heavy exercise with a positive pressure respiratory protective apparatus.

Cardiac output and gas exchange during heavy exercise with a positive pressure respiratory protective apparatus. Scand j work environ health 9 (1983) 471-477. Continuous positive pressure breathing effectively prevents inward leakage of noxious agents into a breathing apparatus but may interfere with venous return and cardiorespiratory performance during heavy work. Cardiac output was therefore recorded with a dye dilution method, and ventilatory variables were measured from expired air, for seven well-trained firemen at a work load of 150 W. All the variables except the invasive ones were also measured during the maximal work load that each subject could sustain for 10 min. At random the subjects worked with a mouthpiece and a face mask with and without a positive pressure of 0.4 kPa. No variable deteriorated during positive pressure breathing, although the central venous oxygen pressure increased, an occurrence indicating higher cardiac output in relation to oxygen demand. Dead space ventilation decreased, an indication of increased ventilatory efficiency. Positive pressure breathing (0.4 kPa) thus does not deteriorate cardiopulmonary function during intermediate or maximal work loads.

Adult↗