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Biomedical subjects

R J Soto

Publications and source records attributed to R J Soto.

13 recordsLinked to original sources
PubMed1992

Effects of ketoconazole on the iodide uptake by FRTL-5 cells.

Ketoconazole is an imidazole derivative used as an antimycotic agent with reported effects on the endocrine system, but very little is known about its possible actions on thyroid function. Our purpose was to study the influence of this substance on the basal and TSH-stimulated iodide uptake in the rat thyroid cell strain FRTL-5. Ketoconazole (1-50 mumol/l) was shown to slightly increase the basal iodide uptake but, at higher concentrations (75-100 mumol/l), it sharply decreased iodide uptake below the basal levels. When the cells were cultured under bTSH stimulation (30 UI/l), the inhibitory effect of ketoconazole was exerted at concentrations as low as 25 mumol/l. This inhibition was observed even if it was added to the culture medium immediately before the Na125I addition. Forskolin, a stimulator of adenylate cyclase activity, was unable to prevent the iodide uptake inhibition. Low doses of ketoconazole increased cAMP concentrations. In the presence of TSH this effect was more evident in an inverse dose-dependent way. Because of its dual action, it can be assumed that ketoconazole could influence the iodide uptake in the FRTL-5 cells through more than one mechanism.

Animals↗
PubMed1992

Graves' disease: evolution and prognosis after eight months of treatment with methimazole.

We studied 26 patients with Graves' disease, from a population with sufficient iodine supply, treated with high doses of methyl mercaptoimidazole (MMI) during eight moths. We evaluated: a) their evolution after treatment withdrawal; b) the correlation between evolution and TSH-receptor antibodies (TRAb), thyroid hormone levels, microsomal antibodies (MAb), T3/T4 index and clinical data; c) their prognosis. The patients were followed during 12-60 months, and blood samples were collected before treatment withdrawal. Out of 26 patients, 20 relapsed, with T3/T4 index and TRAb significantly higher than those under remission. The T3/T4 index correlated with TRAb. All the TRAb-positive patients, and only 57.1% of the negatives, relapsed. The relapses were significantly more frequent prior to the 6th month in the TRAb-positive patients than afterwards. The TRAb-negatives who relapsed during that period, showed TRAb and age means significantly higher than those under remission. The TRAb test, as a prognostic marker of evolution, showed a sensitivity of 60% and a specificity of 100%. No significant differences were found between evolution to relapse or to remission and the other parameters. It can be concluded that TRAb and T3/T4 index were different in the group that relapsed from that which remitted, and that a TRAb positive value, at the moment of treatment withdrawal, is a useful marker of relapse.

Adult↗
PubMed1989

A correlative study between glucocorticoid receptor levels in human mononuclear leukocytes and biochemical data in Cushing's disease.

UNLABELLED: We determined glucocorticoid receptors in human mononuclear leukocytes in 9 patients with Cushing's disease, in order to correlate them with laboratory data. Receptors were measured by a whole-cell assay method, after incubation with [3H]-dexamethasone in the presence or absence of excess unlabelled hormone. In Cushing's disease, there were 4425 +/- 364 sites/cell (N = 9), similar to in the controls: 4473 +/- 476 (N = 10); average Kd was 2.42 +/- 0.52 nmol/l (N = 3) similar to in the controls: 2.0 +/- 0.20 nmol/l (N = 3). In Cushing's patients we found significant negative correlations between basal glucocorticoid receptors and: 1) morning blood cortisol (r = -0.67, P less than 0.05), and 2) 17-ketogenic steroids after 2 mg of dexamethasone (r = -0.85, P less than 0.01). No correlations were observed with afternoon blood cortisol, free urinary cortisol, basal and post-8-mg dexamethasone 17-ketogenic steroids, TRH-TSH area, urinary calcium, plasma glucose, or systolic blood pressure. CONCLUSIONS: In Cushing's disease, a subtle receptor down-regulation may exist, as suggested by the inverse relationship between glucocorticoid receptors and morning blood cortisol. Secondly, the relationship between basal receptors and 17-ketogenic steroids after 2 mg of dexamethasone suggests that glucocorticoid receptors in human mononuclear leukocytes could reflect the sensitivity of the nervous system-pituitary-adrenal axis to dexamethasone inhibition.

17-Ketosteroids↗
PubMed1979

Airway response to hair spray in normal subjects and subjects with hyperreactive airways.

Short-term 20-second exposure to hair sprays A and B failed to show significant decreases in maximum expiratory flow rates at low pulmonary volumes in normal subjects; however, significant decreases were observed with hair spray B in eight subjects with hyperractive airways (abnormal response to inhalation of methacholine). On the partial flow-volume curves, flows at 40 percent and 25 percent of forced vital capacity decreased 8.9 to 10.3 percent and 14 to 18.7 percent, respectively. The hair sprays differed in their content of perfume and plasticizer, and since the latter is generally considered nontoxic at room temperature, the perfume may be the responsible agent. It would appear from this study that normal healthy individuals are at little risk, at least from brief exposure to hair spray; however, in the presence of hyperreactive airways, as seen in asthmatic subjects and in some people with allergic rhinitis and viral respiratory infections, an immediate response of the airways may result from exposure to some hair sprays.

Aerosols↗
PubMed1978

Physiological response to aerosol propellants.

Acute exposures to isobutane, propane, F-12, and F-11 in concentrations of 250, 500, or 1000 ppm for periods of 1 min to 8 hr did not produce any untoward physiological effects as determined by the methods employed which included serial EKG's and continuous monitoring of modified V5 by telemetry during exposure. Repetitive exposures to these four propellants were also without measurable untoward physiological effect with the exception of the eight male subjects repetitively exposed to 1000 ppm, F-11, who did show minor decrements in several of the cognitive tests. Of particular importance is the observation that none of the subjects showed any decrement in pulmonary function or alteration in cardiac rhythm as the result of exposure to concentrations of the gases or vapors far greater than encountered in the normal use of aerosol products in the home.

Adolescent↗
PubMed1977

Acute and repetitive human exposure to isobutane.

Eight adult volunteers of both sexes were exposed to isobutane in a controlled-environment chamber for the purpose of monitoring their physiological responses to a series of gas concentrations ranging from 250 to 1,000 ppm. First, the response to exposure periods of 1 min, 2 min, 1 h, 2 h, and 8 h were studied. There being no untoward responses to these acute exposures, the eight volunteers were exposed repetitively to isobutane at concentrations of 500 ppm, 1, 2 or 8 h per day, five days per week for two weeks. Then exposures to two mixtures of isobutane and propane for 1, 2 or 8 h per day for two days were studied. During the investigation all subjects were kept under comprehensive medical surveillance. No untoward subjective responses or abnormal physiological responses occurred during or following these exposures. Special emphasis was placed on evaluating the cardiac and pulmonary response to these exposures through the use of continuous ECG telemetry and serial computerized spirometric measurements. The following serial laboratory studies were unaltered by the exposures: complete blood count, urinalysis, serum alkaline phosphatase, SGOT, LDH, serum bilirubin, blood sugar, serum calcium, serum phosphorus, BUN, spontaneous electroencephalogram, visual evoked response, a battery of cognitive tests, and an ACTH stimulation test.

Adrenal Cortex↗
PubMed1977

Effect of intraduodenal acid on the pre- and postvagotomy basal gastric secretion and gastrin.

Acid instillation into the duodenum inhibits basal and stimulated gastric secretion. In man vagotomy suppresses this secretory inhibition. It is postulated that such inhibition responds to a dual mechanism: an hormonal one (enterogastrone) and a nervous one (vagus nerve). This study showed that preoperative duodenal acidification of duodenal ulcer patients results in a decrease in basal gastric secretion and in gastrin levels. On the contrary, in patients submitted to vagal denervation--either through truncal division or highly selective vagotomy--duodenal acidification does not inhibit gastric secretion; however, a drop occurs in basal gastrin levels. An intact gastric vagal innervation therefore, seems necessary for the preservation of the sensitivity of the parietal cell to the effect of hormonal inhibitors, it being immaterial whether duodenal innervation is present or not, as that duodenal acidification provokes a significant fall in serum gastrin levels as determined by radioimmunoassay. This hormonal decrease produced by duodenal acidification can be explained by the inhibition of gastrin release from the antrum. Agreement is expressed with the opinion of other authors that highly selective vagotomy does not appear to carry any advantage over truncal section of the vagus nerves from the standpoint of the inhibitory mechanism of gastric secretion from the duodenum.

Duodenum↗
PubMed1975

Effect of sojourn at 4,300 m altitude on electroencephalogram and visual evoked response.

The purpose of the present study was to determine the effect of sojourn at high altitude on cerebral electrical activity. Electroencephalographic (EEG) and visual evoked responses (VER) were recorded from seven healthy males under the following conditions: 1) during the first 2-3 h at 4,300 m altitude when Pao2 was maintained at 90 mmHg (control condition), 2) during the first 2-3 h of hypoxia (Pao2 = 40 mmHg), and 3) at 24- to 48-h intervals during the first 9-12 days of hypoxia. Electrode placement was according to the 10-20 International Electrode System. The VER was recorded from an electrode at the inion referred to the left ear. We found no significant changes from control cerebral electrical activity during the first 2-3 h of hypoxia. One subject's VER amplitude was greater than control on the 2nd and 3rd days of hypoxia and a similar change from control was consistently evident in a second subject beginning the 5th day of hypoxia. These changes suggest cortical depression. After the 5th day changes occurred in the remaining subjects which would be consistent with cortical excitation. In three subjects, EEG frequency was increased, amplitude decreased, and/or spiking became evident. In four subjects VER amplitude was reduced. Our findings provide support for the hypothesis that certain behavioral and physiological changes induced by sojourn at altitude could be caused by alterations in central nervous system function.

Acclimatization↗
PubMed1975

Computerized method for analyzing maximum and partial expiratory flow-volume curves.

Computerized instrumentation and software have been developed to obtain maximum expiratory flow-volume (MEFV) and partial expiratory flow-volume (PEFV) curves. The computerized system calculates and prints out the flow at 25% and 40% of control vital capacity (VC), the expiratory volume, peak expiratory flow rate and expiratory volume at one second (FEV1) divided by VC, the latter expressed as a percent. The flow-volume curves can be displayed on an oscilloscope or plotter and stored on magnetic tape. A pilot study was completed to demonstrate the reliability and validity of the data obtained.

Computers↗