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Biomedical subjects

D S McCann

Publications and source records attributed to D S McCann.

At least 37 records · Page 2Linked to original sources
PubMed1979

Renin, cortisol, and aldosterone during transcendental meditation.

The effects of transcendental meditation (TM) on plasma renin activity (PRA) and plasma concentrations of aldosterone, cortisol, and lactate were studied by measuring these variables before, during, and after 20--30 min of meditation. Subjects, who rested quietly rather than meditating, served as controls. There were no differences in the basal values for these variables between meditators and controls, but controls, in contrast to meditators, showed a significant increase in cortisol between the first (A) and second (B) samples of the control period. PRA increased slightly (14%) but significantly (p less than 0.03) during TM, but not during quiet rest in controls. Cortisol decreased progressively (after sample B) throughout the experiment to the same degree in both groups. Aldosterone and lactate did not change. The data do not support the hypothesis that TM induces a unique state characterized by decreased sympathetic activity or release from stress, but do suggest that meditators may be less responsive to an acute stress.

Adult↗
PubMed1979

Diurnal variations in unconjugated and total plasma estriol levels in late normal pregnancy.

Diurnal variations in plasma unconjugated and total estriol were assessed in 11 third-trimester subjects with uncomplicated pregnancies. Commercially available 125I-labeled radioimmunoassay kits were used. Total plasma estriols reach a nadir during the hours of sleep (400 and 700 hours) which exceeds the episodic fluctuations seen from day to day or during a given 90-minute period. Plasma unconjugated estriol fluctuations over 24 hours did not significantly exceed our previously reported episodic fluctuation of 15.6 +/- 8.2%. The data are interpreted as showing no circadian rhythm, but reflecting, in the case of total plasma estriols, an effect of improved renal clearance during hours of rest. Plasma unconjugated estriol emerges as the test of choice in the monitoring of high-risk pregnancies.

Adult↗
PubMed1978

The relationship of maternal anxiety, plasma catecholamines, and plasma cortisol to progress in labor.

The relationships among maternal anxiety, selected stress-related biochemical factors, and progress in three defined phases of labor were determined for 32 married, normal, primigravid women, 20 to 32 years of age. Comparisons of plasma epinephrine, norepinephrine, and cortisol in third-trimester pregnancy, during labor, and after delivery are provided. At the onset of Phase 2 of labor (3 cm. of cervical dilatation), self-reported anxiety and endogenous plasma epinephrine are significantly correlated. With the deletion of subjects to control for the effect of medications, higher epinephrine levels are significantly associated with lower uterine contractile activity at the onset of Phase 2 and with longer labor in Phase 2 (3 to 10 cm. of cervical dilatation). The relationship between epinephrine and progress in labor is explained by an adrenoreceptor theory.

Adult↗
PubMed1978

Temperature and species differences in susceptibility of kidney cell cultures to mercury toxicity.

The effect of temperature on inorganic mercury toxicity was investigated using kidney tissue culture systems. The relative susceptibility of rabbit (homeothermic) kidney to mercury intoxication was compared to that of Coho salmon (poikilothermic) kidney to mercury intoxication was compared to that of Coho salmon (poikilothermic) kidney over temperature ranges consistent with the habitat of each of the two species. It was demonstrated that susceptibility to mercury toxicity is species dependent; that is, the rabbit kidney cells tolerated higher mercury concentrations in the medium than did the fish-derived cells. Within a given species, susceptibility to mercury toxicity was temperature dependent. Decreasing the temperature increased the toxicity of mercury to cultures of rabbit kidney cells, whereas decreasing temperatures decreased the effect of mercury toxicity on the salmon kidney cells. As a consequence, fish taken from arctic waters are liable to be more toxic when introduced into mammalian food chains. Albumin was shown to act as a protective agent in vitro against inorganic mercury toxicity.

Animals↗
PubMed1978

Plasma estriol vs. estrogen assays in 24-h urines as an index to fetal status.

Conventionally, urinary estrogens are measured to monitor fetal well-being in the third trimester of pregnancy. There are many theoretical and practical advantages to the use of recently introduced plasma estriol assays; consequently, we undertook to compare the results of a spectrophotometric assay for total urinary estrogen with values for plasma total and free (unconjugated) estriol obtained by radioimmunoassay with commercially available kits. The data correlate well, r = 0.70 for plasma total estriol with urinary estrogen (expressed as milligrams of estrogens per gram of creatinine [E/C]), r = 0.79 for plasma free estriol with E/C, and r = 0.71 between the two plasma values. Minute-to-minute fluctuations during 90 min and day-to-day fluctuations followed during five days suggest that fluctuations of up to +/- 45% are within the normal range (means +/- SD of the day-to-day fluctuations were 16.9 +/- 7.7% and 15.6+/- 8.2%). Turn-around time is a minimum of 29 h for the urinary estrogen assay, 4.5 h for the plasma total estriol, and 3 h for the plasma free estriol.

Estriol↗
PubMed1977

Endogenous plasma epinephrine and norepinephrine in last-trimester pregnancy and labor.

Plasma epinephrine and norepinephrine concentrations during labor and immediately after delivery were compared to those of the third trimester in 21 uncomplicated pregnancies of married primigravid women, 20 to 32 years old. Third-trimester catecholamine concentrations were similar to those of normal, nonpregnant subjects; samples were obtained under identical conditions. Compared to third-trimester levels, significant elevations of plasma epinephrine and norepinephrine were found in three phases of labor (at 3 to 5 cm. and 9 to 10 cm. of cervical dilatation and immediately after delivery). Epinephrine values returned to normal within three to 21 minutes after delivery; norepinephrine values remained high or continued to rise in this time interval. Maternal analgesia and anesthesia influenced plasma catecholamine levels.

Adult↗
PubMed1977

Plasma androgen concentrations in diabetic women.

Plasma androgen levels were determined in women assigned to the following groups: idiopathically hirsute, diabetic, both idiopathically hirsute and diabetic, and normal. The androgens examined were androstenedione (AD), dihydrotestosterone (DHT), testosterone (T), and dehydroepiandrosterone (DHEA). We find statistical differences between young (less than 38 years) and older (larger than or equal to 38 years) controls at confidence levels of p less than or equal to 0.01 for AD, DHT, and T and of p less than or equal to 0.05 for DHEA. The results indicate that peak circulating androgen levels occur prior to age 30-35 years for women. There are no significant differences between the young controls and young idiopathically hirsute subjects, but a statistical difference exists between older hirsute and older controls for all four androgens (p less than or equal to 0.05). When a comparison is made among the diabetic, hirsute diabetic, and older control groups (all groups larger than or equal to 38 years), the diabetic group is significantly higher than the control in plasma AD (p less than or equal to 0.01) and DHEA (p less than or equal to 0.05). These same two steroids are also higher in the diabetic group than in the hirsute diabetic group (p less than or equal to 0.05), while the latter differs from controls only in testosterone levels (p less than or equal to 0.05). DHT levels are similar for all three groups.

Adult↗
PubMed1976

Evaluation of transcendental meditation as a method of reducing stress.

Transcendental meditation is said to induce in its practitioners an altered state of consciousness resulting in relief of stress, an increased sense of awareness, and a sense of well-being. Release of catecholamines has been associated widely with stress and lends itself to quantitation. Plasma epinephrine and norephinephrine, as well as lactate, were measured in 12 volunteers before, during, and after meditation. Values were compared with those obtained from controls matched for sex and age who rested instead of meditating. Essentially the same results were obtained for the two groups, which suggests that meditation does not induce a unique metabolic state but is seen biochemically as a resting state.

Adult↗
PubMed1976

Evaluation of serum ionic calcium measurement in a general hospital population.

Direct measurement of ionic calcium was evaluated in light of conflicting reports concerning the correlation of ionic calcium with total calcium and ionic calcium as predicted from total calcium and serum protein. Ionic calcium in the sera of normo- hypo-, and hypercalcemic adult hospitalized patients was measured anaerobically using an Orion model 98-20 calcium flow-thorugh electrode. Good correlation (r = .77) was found with the calculated ionic calcium value derived from total protein and total calcium, using the McLean-Hastings nomogram. Good correlation was also present between the measured ionic and total calcium (r = .80). In view of these correlations, the introduction of serum ionic calcium measurements into the general hospital laboratory repertoire is of questionable value.

Calcium↗
PubMed1975

Clinical determination of methemalbumin.

We developed an assay for methemalbumin in biological fluids by using diethylaminoethyl-Sephadex ion-exchange chromatography to separate this protein from interfering components, including hemopexin, transferrin, hemoglobin, and haptoglobin/hemoglobin complex. Initial screening of the samples requires measurement of A280/A405 ratios of the peak tubes of the isolated albumin fraction. Values exceeding 30 indicate that methemalbumin is absent, and no further work is required. Values of less than 30 suggest that methemalbumin is present in the original sample, whereupon the presence and amount of methemalbumin can be ascertained by coloremetric assay for iron with use of ferrozine. Results may be expressed either in terms of micrograms of methemalbumin iron per gram of albumin or in milligrams of methemalbumin per liter. The reproducibility of the method is of the order of +/- 7% (SD). Normal persons have essentially no methemalbumin iron in their serum. Three individuals with hemorrhagic pancreatitis showed values of 65, 98, and 198 mug of methemalbumin Fe per gram of albumin.

Acute Disease↗