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Biomedical subjects

R D Stewart

Publications and source records attributed to R D Stewart.

At least 145 records · Page 8Linked to original sources
PubMed1976

Rapid estimation of carboxyhemoglobin level in fire fighters.

The analysis of expired breath with a portable electrochemical cell after carbon monoxide exposure provides a practical field method for the rapid estimation of carboxyhemoglobin. A fire fighter can collect and analyze his own breath sample for CO, an operation that requires 1 1/2 minutes. This simple technique has the accuracy necessary to determine compliance with the regulations governing occupational exposure to CO.

Blood Gas Analysis↗
PubMed1976

Paint-remover hazard.

The in-home use of paint removers containing methylene chloride results in the absorption of this solvent, which is metabolized to carbon monoxide. Exposure for two to three hours can result in the elevation of carboxyhemoglobin (COHb) to levels that stress the cardiovascular system. The metabolic formation of COHb continues following the paint-remover exposure, doubling the duration of the cardiovascular stress produced by a comparable COHb level after exposure to CO. Patients with diseased cardiovascular systems may not be able to tolerate this unexpected stress.

Adult↗
PubMed1976

Anorectal pruritus after intravenous hydrocortisone sodium succinate and sodium phosphate.

A double-blind study demonstrated that single intravenous doses of 100, 200, or 400 mg of hydrocortisone sodium succinate and hydrocortisone sodium phosphate were similar in eosinophil suppression, elevation of glucose, white blood count differential shifts (polymorphonuclear cells, lymphocytes, and monocytes), and urinary excretion of sodium and potassium but not in incidence of side effects. More subjects receiving hydrocortisone sodium phosphate experienced systemic or localized adverse effects than those receiving hydrocortisone sodium succinate. The most common side effect was burning or itching in the anorectal area, which occurred in 16 of 18 subjects medicated with hydrocortisone sodium phosphate, in 1 subject of 6 treated with placebo (saline), and in none who received the sodium succinate. The effect is attributed to the phosphate steroid and appears to last as long as it takes to convert to cortisol.

Adult↗
PubMed1976

The metabolism of [75Se]selenomethionine in four women.

1. The long-term fate of an oral dose [75Se]selenomethionine was studied in four women. 2. Urinary and faecal excretion, respiratory losses and whole-body retention of 75Se were measured, and also 75Se turnover in whole body, plasma and erythrocyte during a period of 33-34 weeks. 3. Intestinal absorption of [75Se]selenomethionine by the four subjects was 95.5-97.3% of the administered dose. 4. Urinary excretion accounted for 6-9% of absorbed 75Se in the first 2 weeks. No radioactivity was detected in expired air.

Adult↗
PubMed1976

Histocompatibility antigens in Graves' disease.

Histocompatibility antigen typing was undertaken in 100 Caucasian patients with Graves' disease (autoimmune thyrotoxicosis) and in 100 healthy Caucasian blood donors. Standard lymphocyte microcytotoxicity methods were used to tests for the presence of 22 HL-A antigens in all subjects. There was a significant difference between the groups in respect of the HL-A 8 antigen which was present in 40 patients and in 25 controls (P less than 0-0023). There was no significant difference between the patients and controls with respect to the frequency of occurrence of any of the other HL-A antigens tested.

Adult↗
PubMed1976

Evidence that mouse thyroid stimulator does not stimulate the human thyroid gland.

Thyroid 131I uptake and human thyroid stimulator (HTS) level were measured in 20 untreated thyrotoxic patients who also showed mouse thyroid stimulator (MTS) ACtivity. The correlation between thyroid uptake and HTS level was highly significant (P less than 0-005), the coefficient, r, being 0-66, comparable with the value 0-68 obtained in a previous study of patients not showing MTS. Thus, the presence of widely varying amounts of MTS does not impair the close correlation existing between HTS level and thyroid 131I uptake in thyrotoxic people. There was no correlation between MTS level and thyroid 131I uptake (r = 0-11, n.s.). It is concluded that MTS, a potent stimulator of the thyroid glands of mice, guinea pigs and monkeys, does not stimulate the human thyroid gland.

Animals↗
PubMed1976

Effects of propranolol on changes in heart rate, heart weight, kidney weight, urinary hydroxyproline and weight gain induced by large doses of thyroxine in the rat.

The effects of the beta-adrenergic receptor blocking agent, DL-propranolol, and of the antithyroid drug, carbimazole, upon some manifestations of thyroxine (T4)-induced changes in peripheral metabolism were studied in rats. Propranolol lowered the heart rate, but did not alter the following changes induced by T4: increment in heart rate, increase in heart or kidney weight, increase in urinary hydroxyproline, decrease in body weight gain or increase in serum T4. Carbimazole administration lowered serum T4 and reduced weight gain, but had no effect upon heart rate or hydroxyproline excretion.

Animals↗
PubMed1976

Use of breath analysis to monitor methylene chloride exposure.

Twenty male and female subjects were exposed repetitively to methylene chloride (CH2Cl2) vapor, 50, 100, 250, and 500 ppm, for 1,3, or 7.5 h in a controlled-environment chamber. Postexposure alveolar breath samples were collected in small glass breath tubes and analyzed for CH2Cl2 by gas chromatography. From these data is a series of breath CH2Cl2 excretion curves were constructed that can be used to estimate the magnitude of a recent exposure. The CH2CL2 breath concentration in the immediate postexposure period accurately reflected the vapor concentration to which the subjects had been exposed most recently. Breath samples collected 1--2 h following exposure were accurate indicators of the time-weighted average vapor exposure experienced by the subjects during the previous 8 h of occupational exposure. Breath analysis offers a practical, noninvasive method for monitoring occupational exposure to CH2Cl2.

Adult↗
PubMed1975

Metabolic studies of [75Se]selenocystine and [75Se]selenomethionine in the rat.

1. The long-term fate in rats of an oral dose of [75Se]selenocystine was compared with that of an oral dose of [75Se]selenomethionine. 2. Urinary and faecal radioactivities were measured during the 1st week and whole-body radioactivity was determined for 10 weeks. Rats were killed at weekly intervals for 4 weeks and at weeks 6 and 10 for analysis of tissue distribution of 75Se. 3. Intestinal absorption of [75Se]selenocystine was 81% of the administered dose; that of [75Se]selenomethionine was 86%. Urinary excretion of absorbed [75Se]selenocystine was 13-9% and that of [75Se]selenomethionine was 5-8% in the 1st week. 4. Whole-body retention of 75Se was greater for [75Se]selenomethionine than for [75Se]selenocystine but after the 1st week it decreased at a similar rate in both groups. Tissue distribution of retained 75Se was also similar in both groups. 5. The initial utilization of [75Se]selenocystine was different from that of [75Se]selenomethionine. However, after the 1st week 75Se from both sources appeared to be metabolized similarly, suggesting that dietary Se of both forms is ultimately incorporated into the same metabolic pool. 6. When these findings were compared with those of earlier studies with [75Se]selenite and 75Se incorporated in vivo into rabbit kidney (RK-64Se) (Thomson, Stewart & Robinson, 1975) the metabolism of [75Se]selenocystine resembled that of [75Se]selenite and RK-75Se, rather than that of [75Se]selenomethionine.

Amino Acids, Sulfur↗
PubMed1975

Metabolic studies in rats of (75-Se)selenomethionine and of 75-Se incorporated in vivo into rabbit kidney.

1. [75-Se]selenomethionine was administered to four rabbits and after 4 d their kidneys were removed and homogenized. The long-term fate in rats of an oral dose of this kidney homogenate (RK-75-Se) was compared with that of an oral dose of ]75-Se]selenomethionine mixed with unlabelled rabbit kidney homogenate. 2. Urinary adn faecal radioactivities were measured during the 1st week and whole-body radioactivity was determined for 10 weeks. Rats were killed at weekly intervals for 4 weeks for analysis of tissue distribution of 75-Se. 3. Intestinal absorption of RK-75-Se was 87%; that of [75-Se]selenomethionine was 91%. Urinary excretion of absorbed RK-75-Se was 13-3% and that of [75-Se]selenomethionine was 7-6%, in the 1st week. 4. Whole-body retention of 75-Se was greater for [75-Se]selenomethionine than for RK-75-Se but after the 1st week decreased at a similar rate in both groups. Tissue distribution of retained 75-Se was also similar in both groups. 5. The initial utilization of 75-Se in rabbit kidney is different from that of [75-Se]selenomethionine. However, after the 1st week 75-Se from these sources appears to be metabolized similarly, suggesting that Se from both is ultimately incorporated into the same metabolic pool.

Animals↗
PubMed1975

Predicting the carboxyhemoglobin levels resulting from carbon monoxide exposures.

Data from a series of human exposures to carbon monoxide (CO) were analyzed to determine the fit to the theoretical Coburn-Forster-Kane (CFK) equation which describes CO absorption and excretion. The equation was found to predict carboxyhemoglobin (HbCO) saturations for both men and women at exercise rates ranging from sedentary to 300 kpm/min when they were exposed to steady CO concentrations of 50, 100, and 200 ppm for 0.33-5.25 h. Methods for determining values of each of the variables in the CFK equation were collected and a rational, efficient procedure for solving the equation by trial and error was outlined. The CFK equation was then used to prepare a graph, relating HbCO saturation to exposure duration and concentration, and also to describe the effect of several variables on the rate of CO uptake and equilibrium HbCO levels, important considerations in the determination of permissible public, occupational, and experimental exposure to CO.

Air Pollutants↗