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Biomedical subjects

M A Mishkel

Publications and source records attributed to M A Mishkel.

At least 19 recordsLinked to original sources

Occupational screenings: recruitment from private industry.

Occupational screening involving private sector employees represents a source with relatively high volumes of initial contacts and entries, a low ratio of entries to initial contacts, and a relatively high effort level requirement for the recruitment team. In the CPPT, all centers used this strategy, to provide, overall, 26% of initial contacts, 20% of first protocol visits and 17% of entries. Occupational screening is costly and involves careful planning and implementation of complex arrangements. Procedures for contacting industries and conducting screenings are described. Screening yield was inversely related to company size.

Adult

Pancreatitis, familial hypertriglyceridemia, and pregnancy.

Interrelationships between pregnancy, hypertriglyceridemia, and pancreatitis were assessed in three women with familial hypertriglyceridemia. One subject had known familial hypertriglyceridemia, familial type V hyperlipoproteinemia, prior to conception. In this woman a progressive increase in triglyceride levels to more than 3,000 mg/dl during the first two trimesters required dietary intervention and hospitalization at 28 weeks' gestation. Use of an isocaloric National Institutes of Health type V diet reduced triglyceride levels to less than 900 mg/dl; the pregnancy was uneventful with term delivery of a healthy neonate. The familial hypertriglyceridemia was covert in the other two women until term. In one subject, subsequently shown to have familial type V, acute hemorrhagic pancreatitis with a pancreatic pseudocyst, shock, and hypocalcemia developed at 39 weeks' gestation; the neonate was safely delivered, and the mother survived. In the second, entirely asymptomatic subject, triglyceride levels greater than 5,000 mg/dl were discovered incidentally at term cesarean section during delivery of a healthy neonate. With a fat restricted diet, plasma triglyceride levels abruptly fell post partum to less than 500 mg/dl, and subsequent studies revealed familial type III hyperlipoproteinemia. Routine quantitation of plasma cholesterol and triglyceride levels or simple visual examination of fasting plasma for triglyceride-induced opacity or "milky" appearance should be done during early pregnancy. This would allow the obstetrician to identify women with severe familial hypertriglyceridemia prior to the superimposition of the physiologic hyperlipidemia of pregnancy upon familial hypertriglyceridemia with resultant, and often catastrophic, acute pancreatitis.

Adult

Plasma lipoprotein levels and the prevalence of hyperlipoproteinemia in a Canadian working population.

The lipids and lipoproteins - cholesterol (C), triglyceride (TG) and high-density, low-density, very-low-density and sinking pre-beta-lipoprotein cholesterol (HDL-C, LDL-C, VLDL-C and SPB-C) - in plasma samples from 1620 fasting white adults and children from the Toronto-Hamilton area were analysed. The mean concentration of HDL-C was about 45 mg/dl in men and about 60 mg/dl in women, and the levels were constant throughout adult life in both sexes. Boys had higher mean HDL-C levels than men, but girls had lower mean HDL-C levels than women. Mean LDL-C levels, like total C levels, increased with age, from about 87 mg/dl in boys to 136 mg/dl in men, and from about 91 mg/dl in girls to 145 mg/dl in women. The mean levels of VLDL-C followed the TG patterns for age and sex, rising from about 7 mg/dl in boys to 26 mg/dl in men, and from about 11 mg/dl in girls to 19 mg/dl in women. SPB-C was detectable visually in 39% of the population and with the aid of densitometry in 54%; the levels were not related to age, sex or oral contraceptive use, and the median level was 3 mg/dl.Prevalence estimates of hyperlipoproteinemia showed that type IV was the most common, and it was found more than three times as often in men as in women. This was in part due to the customary use of plasma TG cut-off points that do not reflect the large difference in TG levels between males and females. Type IIA hyperlipoproteinemia was found in about 2% of the adults and type IIb in a further 1%. Types I, III and V were all rare. The prevalence of types II and IV hyperlipoproteinemia was four times greater in women using oral contraceptives than in nonusers in the same age range.

Adolescent

Normative standards of plasma cholesterol and triglyceride concentrations in Canadians of working age.

Fasting plasma cholesterol and triglyceride concentrations were determined for 6407 working Canadian adults aged 20 to 69 years in Toronto and Hamilton. Means, medians and 5th and 95th percentiles were ascertained from the data for men, women taking oral contraceptives or estrogen preparations, and women not taking such medication. Mean plasma cholesterol values (mg/dL) ranged in men from 168.3 at ages 20 to 24 years to 211.5 at ages 45 to 49 years, and in women using hormone preparations from 180.3 at ages 20 to 24 years to 224.2 at ages 50 to 54 years; corresponding values in women not using these preparations were 164.9 and 220.6. Plasma triglyceride means (mg/dL) ranged in men from 108.7 at ages 20 to 24 years to 166.7 at ages 40 to 44 years, in women using hormone preparations from 115.4 at ages 20 to 24 years to 145.3 at ages 45 to 59 years, and in women not using these preparations from 77.5 at ages 20 to 24 years to 112.4 at ages 50 to 54 years.

Adult

Hypothyroidism, an important cause of reversible hyperlipidemia.

Primary hypothyroidism was found to be the cause of hyperlipidemia in 22 patients. The mean age was 46 years, 59% were males, 27% had vascular disease, 14% had xanthomas and 86% had thyroid antibodies. Familial involvement was shown in 3 propositi. All patients were treated with L-thyroxine, 0.05--0.2 mg/day for a mean of 16 months. Combined hyperlipidemia was common (77%), and lipoprotein phenotyping revealed types IIB hyperlipopro-teinemia in 11, IIA in 5, III in 3 and IV in 3 patients. With treatment, normal plasma cholesterol (less than 265 mg/dl) and triglycerides (less than 200 mg/dl) were obtained in 91% and 86%, respectively. The mean maintenance L-thyroxine dose was 0.15 mg/day, but smaller doses often showed marked hypolipidemic effect. The mean +/- S. D. pretreatment fasting plasma cholesterol and triglycerides were 387 +/- 120 and 328 +/-247 mg/dl and on thyroid treatment the mean minimum levels were 205 +/- 46 and 133 +/- 65 mg/dl, respectively (both p values less than 0.005). Hypothyroidism has proved to be a common reversible form of hyperlipidemia. One cardiac patient died and three others had to have their L-thyroxine titrated to prevent angina. Family screening has been of use in case finding for auto-immune disease in 3 families.

Adolescent

Xanthoma disseminatum. Clinical, metabolic, pathologic, and radiologic aspects.

A 55-year-old man with the classical mucocutaneous lesions of xanthoma disseminatum has been followed up for a period of 13 years. The special features of this case, which make it unique, are as follows: (1) the availability of histologic data on multiple lesions for more than a ten-year period; (2) the progressive nature of the multiple osseous lesions; (3) the metabolic studies that show no evidence for accumulation of abnormal sterols in a xanthoma, the blood, or intestinal aspirate; (4) the development of hypothyroidism and symptoms or signs, or both, of an intracerebral and an intraspinal lesion; (5) the partial regression of the cutanous symptoms and lesions while receiving clofibrate, in spite of progression of the mucous membrane and osseous lesions, and (6) the failure to develop diabetes insipidus to date.

Anus Diseases

Pseudohomozygous and pseudoheterozygous type II hyperlipoproteinemia.

A 4-year-old boy had typical features of homozygous type II hyperlipoproteinemia with planar xanthomas, a plasma cholesterol level greater than 600 mg/dl, and an estimated beta-lipoprotein cholesterol concentration greater than 500 mg/dl. Both he and his sister, who had the biochemical features of the heterozygous state, responded unusually well to a diet low in saturated fat and cholesterol content. These features, combined with the finding of normocholesterolemic parents, are highly suggestive of a newly described syndrome. pseudohomozygous type II hyperlipoproteinemia.

Adult

Fatty acid composition of margarines.

The fatty acid composition of 27 samples of bar margarines, 58 samples of tub margarines, and one sample of a liquid margarine spread, purchased at different centers in Canada and the United States over a 1-year period (1973-1974), has been determined. The values of total polyunsaturated fatty acids determined by gas-liquid chromatography were compared to the results obtained by an enzymatic method using lipoxidase. The margarines have also been compared on the basis of fatty acid composition and polyunsaturated to saturated fatty acid ratios. All of these parameters showed considerable variations among the different samples analyzed in this study. As a general rule, soft (tub) margarines tended to have a higher concentration of cis,cis-9,12-octadecadienoic (linoleic) acid than hard (bar) margarines. The labeling of the products as regards fatty acid composition was not always helpful in choosing a margarine of high linoleic acid composition.

Canada

The effect of calcium on plasma lipids and bile acid and fecal fat excretion in normolipidemic subjects.

The effect of oral calcium (2 g/day) was studied in four normolipidemic subjects. Calcium caused a significant lowering of plasma cholesterol and a considerable fall in the glycine-/taurine-conjugated bile acid ratio in the intestinal aspirate of one subject, while fecal bile acid excretion rose appreciably in another during treatment. These parameters showed no consistent trend in the other three subjects. None of the subjects showed any significant change in plasma triglycerides and serum calcium and phosphorus during treatment. One subject showed a consistent decrease in every parameter studied throughout the experiment, a trend which was probably due to a concomitant loss in body weight.

Adult