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Biomedical subjects

M E Stewart

Publications and source records attributed to M E Stewart.

At least 73 records · Page 4Linked to original sources
PubMed1983

Sustainable rates of sebum secretion in acne patients and matched normal control subjects.

Sustainable rates of sebum secretion were measured in twelve subjects with inflammatory acne and in twelve control subjects, matched in age and gender, who had no significant signs of acne. The measurements were made after first depleting the skin of an accumulation of previously secreted sebum by absorption into adherent layers of bentonite clay applied to the center of the forehead for 14 hours. Disks of fine Dacron mesh, embedded in fresh clay, were then applied to the forehead for 3 hours. The disks and adhering clay were then removed and extracted with ether to recover the collected lipids. The sebum recovered during the 3-hour period was measured by quantitative thin layer chromatography. The subjects with acne were found to have an average sustainable sebum secretion rate of 2.51 mg/10 cm2/3 hr, while the control group had an average of 0.81 mg/10 cm2/3 hr. Furthermore, all subjects with acne had secretion rates larger than those of their matched control subjects. The results indicate that a high sebum secretion rate is the decisive factor in inflammatory acne.

Acne Vulgaris↗
PubMed1983

Effect of oral 13-cis-retinoic acid at three dose levels on sustainable rates of sebum secretion and on acne.

Changes in sustainable rates of sebum secretion were followed in twenty patients with severe acne who were receiving oral treatment with 13-cis-retinoic acid in dosages of 0.1, 0.5, or 1.0 mg/kg/day. Sebum secretion was measured by absorption of skin surface lipid into bentonite clay and estimation of the amount of absorbed sebum by measurement of its wax ester component. Pretreatment rates of sebum secretion in the patients were greatly elevated in comparison with previously measured values in young adult subjects without acne. After 4 weeks of treatment, mean rates of sebum secretion on all three dose levels fell to or below the range for normal subjects. On-treatment rates of sebum secretion were significantly lower in patients on the highest dose compared to patients on the lowest dose. When the drug was discontinued, rates of sebum secretion recovered slowly. Clinical response was excellent in most of the subjects. The five subjects with least favorable response clinically all had better than average suppression of sebum production.

Acne Vulgaris↗
PubMed1983

Intestinal protozoan infection in a semicommunal group.

A survey was conducted to determine the prevalence of protozoan parasites in a large semicommunal group in Los Angeles. Protozoan parasites were observed in 151 (69%) of the 220 group members in the study. Parasites were observed in stool specimens from 105 (76%) of the 138 children and 46 (56%) of the 82 adults. Dientamoeba fragilis was observed in 115 (52%), Giardia lamblia in 50 (23%), Entamoeba histolytica in 9 (4%), and commensals in 61 (28%). Parasitic infection was infrequent in infants less than 1 year old, was demonstrated in 33 (89%) of the 2- to 4-year-olds, 69 (78%) of the 89 school age children 8-15 years of age, and in 46 (56%) of the 82 adults. G. lamblia was most prevalent in children younger than 6 years; whereas D. fragilis was common in all age groups. The fecal-oral route was the most likely means for parasite transmission. Since the group at times serves meals to the public, spread of parasites outside the community is a potential public health problems. Diagnosis of parasitic infection is dependent on optimal stool collection, proper laboratory techniques and trained personnel.

Adolescent↗
PubMed1983

Coronary artery stenoses. Relationship between angiographic severity and impact on mean diastolic pressure gradient.

Coronary angiography provides important anatomic information about coronary artery stenoses. However, it is unclear whether specific assumptions about hemodynamic impact can be made from the angiogram. We therefore studied the relationship between angiographic severity of coronary stenoses and the mean diastolic pressure gradient measured directly at coronary bypass operation. We studied 29 stenoses selected because they were the only lesions in a given vessel, they were well seen in two angiographic views, and there was no change in clinical status of the patient between angiographic and surgical procedures. Fourteen stenoses were in the left anterior descending artery, nine were in the right coronary artery, and six were in the left circumflex artery. Correlation between mean diastolic gradient and percent stenosis was good (r = 0.78, p = 0.001) and especially so for lesions in the left anterior descending artery (r = 0.84, p = 0.001). Lesions over 90% had a wide range of gradients, while lesions less than 90% tended to have more predictable gradients. Collaterals invariably identified vessels with stenoses causing major pressure gradients. History of myocardial infarction was associated with major gradients in supplying vessels. Length of stenosis was not an important influence on gradient over a stenosis. We conclude that in some defined instances, generalizations about hemodynamic (and presumed functional) impact of stenoses can be made from the angiographic assessment, but precise assumptions are not possible.

Adult↗
PubMed1982

Variability in the fatty acid composition of wax esters from vernix caseosa and its possible relation to sebaceous gland activity.

Wax ester/sterol ester (WE/SE) ratios were measured in samples of vernix caseosa lipid obtained from 21 full-term infants. The mean WE/SE ratio was twice as high in males as in females, suggesting higher average fetal sebum production rates in males, but individual values varied widely and there was considerable overlap between the sexes. Wax esters (a class of lipid produced only by the sebaceous glands) were isolated from 6 of the 21 samples of vernix caseosa lipid and analyzed for fatty acid composition. The percentages of iso and anteiso branched saturated fatty acids and of delta 9-type monounsaturated fatty acids were found to be correlated negatively with the WE/SE ratios of the original lipid samples. Values for the percentages of the major delta 9-type monounsaturates, plotted as a function of WE/SE ratios, fell near a curve of the shape which would be expected if a limited quantity of delta 9-type monounsaturates were available for sebum synthesis, and were diluted with varying amounts of delta 6-type monounsaturates, the amount of the delta 6-type monounsaturates being proportional to the amount of wax esters synthesized by the sebaceous glands. The results suggested that the rate of sebum production may be the sole determinant of the percentage of delta 9-type monounsaturates in sebaceous wax esters and a partial determinant of the percentage of iso and anteiso branched saturates.

Esters↗
PubMed1982

Uterine leiomyomas, serum cholesterol, and oral contraceptives. A preliminary study of epidemiologic differences in Los Angeles, California and Albany, New York.

In order to determine the feasibility of a large-scale study to investigate the relationship of serum cholesterol levels to the presence or absence of uterine leiomyomas, the medical records of 67 women aged from 30 to 39 who underwent hysterectomies at UCLA Hospital, Los Angeles, and Albany Medical Center, Albany, New York were reviewed. The women at UCLA were more likely to have a history of oral contraceptive use than were the women in Albany; they also had higher serum cholesterol values. In both hospitals, increasing age was associated with the presence of leiomyomas, and oral contraceptive use was associated with absence of pathology in the resected uterus. In Albany, but not in Los Angeles, oral contraceptive uterus. In Albany, but not in Los Angeles, oral contraceptive use was associated with elevated serum cholesterol, As expected, uterine weight and presence of leiomyomas were strongly associated. It was concluded that serum cholesterol levels were apparently unrelated to presence of uterine leiomyomas and to uterine weight in this group of women. Recommendations are made for the design of a case-control study to further investigate both the cholesterol-leiomyoma relationship and the other results reported here.

Adult↗
PubMed1981

Separation of wax esters from steryl esters by chromatography on magnesium hydroxide.

Chromatography of stearyl oleate and cholesteryl oleate on thin layer plates coated with magnesium hydroxide-celite, 1:1, or magnesia-celite, 1:1, showed that magnesium hydroxide had better resolving power for the separation of these wax ester and steryl ester model compounds than did magnesia, an adsorbent which has been used previously for this separation. By means of high pressure liquid chromatography on magnesium hydroxide, wax esters and steryl esters from the skin surface lipids of human, rat and monkey were separated completely and without hydrolysis.

Animals↗
PubMed1981

First-aid treatment of poisonous snakebite: are currently recommended procedures justified?

A survey of the literature on first-aid treatments for poisonous snakebite reveals conflicting recommendations. A subsequent review of experiments and case surveys investigating such treatments indicates that the most commonly recommended procedures (incision and suction, ligation, and ice-packing of the bite) are not well supported by experimental evidence, and may possibly be harmful. We suggest that further clinical research and case studies are necessary in order to determine safe and effective first-aid procedures for the bites of American poisonous snakes.

Cryosurgery↗
PubMed1981

Estimation of sebum production rates in man by measurement of the squalene content of skin biopsies.

Previous studies have shown that lipids are synthesized at a constant rate in sebaceous glands and secreted onto the skin surface an average of 8 days after synthesis. As a result, measurement of the sebum content of a skin specimen of known surface area should allow calculation of the sebum production rate which had been occurring in vivo. In the present study, such measurements have been made on scalp skin specimens from 14 men. The amount of sebum in 4-mm punch biopsies was calculated from the squalene content of the specimens, as measured by quantitative thin-layer chromatography of lipid extracts. The average sebum production rate for the group was found to be 1.45 mg/10 sq cm/3 hr.

Humans↗
PubMed1980

Effect of long-term psychosocial stimulation on mental development of severely malnourished children.

The effect of adding psychosocial stimulation to the treatment of severely malnourished children was studied by comparing the developmental levels (DQs) of the children with those of two other groups of children--an adequately nourished group with diseases other than malnutrition and a second malnourished group who received standard hospital care only. The intervention children underwent structured play sessions daily in hospital and weekly for 6 months after discharge; mothers were also shown how to play with them. The non-intervention malnourished group showed a marked deficit in DQ compared with the adequately nourished group throughout the study period. The intervention group made significant improvements in DQ in hospital and continued to do so after discharge. By 6 months they were significantly ahead of the non-intervention malnourished group, and were no longer significantly behind the adequately nourished group.

Anthropometry↗
PubMed1980

Fibre-optic bronchoscopy in small cell lung cancer: findings pre and post chemotherapy.

The aim of our study was to evaluate the role of fibre-optic bronchoscopy both in diagnosing patients with small cell lung cancer, and in assessing remission status following combination chemotherapy. Diagnostic bronchoscopic examination was performed in 40 patients and revealed that in all cases the lesion was located in the central bronchi. Following combination chemotherapy remission status in 18 patients was assessed by comparing the findings at repeat bronchoscopy with those of chest radiology. In ten patients there was no relationship between the findings at bronchoscopic examination and the chest radiograph (normal or abnormal). Adequate assessment of response of small cell lung cancer to therapy requires bronchoscopy in addition to chest radiology.

Bronchoscopy↗
PubMed1978

The fatty acids of human sebaceous gland phosphatidylcholine.

The fatty acids of human sebaceous gland phosphatidylcholine were examined by gas chromatography and by analysis of the double bond positions in the C-16 and C-18 monoenes. Compared to phosphatidylcholine from other organs, sebaceous gland phosphatidylcholine was found to be deficient in essential fatty acids and poly-unsaturated fatty acids. The relatively large mono-unsaturated fatty acid fraction consisted predominantly of fatty acids with delta6- and delta8-unsaturation. Analysis indicates that the fatty acids of sebaceous gland phospholipids are predominantly of types synthesized in sebaceous glands.

Fatty Acids↗
PubMed1977

In-vitro metabolism of [3H]testosterone by scalp and back skin: conversion of testosterone into 5alpha-androstane-3beta, 17beta-diol.

The in-vitro metabolism of [3H]testosterone by human scalp and back skin was examined for possible differences in enzyme activity in skin from these two areas, both of which contain large sebaceous glands but only one of which, the back, is prone to develop acne. Punch biopsy specimens of skin, obtained from the scalp and back of adult men, were minced and incubated with [3H]testosterone. The metabolic products were diluted with carrier steroids, then separated and measured by thin-layer chromatography and by gas chromatography on an instrument equipped with a splitter. The results showed that of the 5alpha-reduced metabolites identified, a major one in both the scalp and back skin incubations was 5alpha-androstane-3beta,17beta-diol. Formation of the androstanediol was especially pronounced in scalp skin where it accounted for up to 50% of the 5alpha-reduced metabolites produced. This finding that 5alpha-androstane-3beta,17beta-diol is a major product of testosterone metabolism in vitro by human skin containing sebaceous glands, supports the possibility, previously suggested by studies in the rat, that this steroid can stimulate sebum secretion.

Androstane-3,17-diol↗