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Biomedical subjects

J F Mackin

Publications and source records attributed to J F Mackin.

7 recordsLinked to original sources
PubMed1980

Effects of biotin on lipids and other constituents of plasma of healthy men and women.

A double-blind study of the effect of biotin supplementation (0.9 mg/day) of self-selected diets on plasma lipids and other plasma constituents was carried out in 40 men and women, age 30 to 60 years, for 71 days. Comparison of percent change from control levels showed significant treatment effects on more plasma constitutents than did comparison of the means of the actual levels. In an analysis of period of period changes, the largest differences were observed generally during the first two weeks after supplementation when small but statistically significant positive changes for biotin-treated men and women differed significantly from changes for the placebo-treated in total lipid, total phospholipid, and alpha + beta lipoprotein cholesterol. At the end of the study, these levels were at or below initial levels. Plasma biotin levels were elevated by biotin supplementation. There was a negative correlation between biotin levels and total plasma lipids. Responses os some lipid constituents of plasma were greater in volunteers who initially had elevated levels of lipids than in those who initially had normal levels of lipids. It is concluded that human requirements for biotin should be studied by new approaches and with modern techniques. Questions raised regarding the role bo biotin in the lipid metabolism of normal men and women should be investigated further.

Adult↗
PubMed1979

Propranolol therapy in thyrotoxicosis. A review of 84 patients undergoing surgery.

The effect of propranolol on the surgical course of 84 thyrotoxic patients undergoing partial thyroidectomy or extrathyroidal surgery was evaluated. Seventy-two patients (group 1) underwent surgery with propranolol as their sole preparatory medication, whereas in 12 (group 2) surgery was carried out after a rather prolonged period of thionamide preparation with the addition of propranolol preoperatively as an adjunctive therapeutic agent. Preoperative pulse rate and systolic blood pressure levels fell in both groups, and the clinical features of thyrotoxicosis were rapidly ameliorated with an average dose of propranolol of 330 mg (range 40 to 1,280 mg) daily. Maximal clinical response occurred within 48 to 72 hours of starting propranolol therapy. In 14 patients in group 1, paired serum calcium levels were reduced by the administration of propranolol preoperatively; serum thyroxine levels were unchanged. Serum thyroxine decay, evaluated postoperatively in the patients in group 1, was decreased. The half life of thyroxine was inversely related to the initial thyroxine levels. Analysis of these data indicates that the administration of propranolol alone provides rapid, safe and effective preparation of thyrotoxic patients for emergency or for elective thyroidal or extrathyroidal surgical procedures.

Adolescent↗
PubMed1976

Changes in lactate dehydrogenase, LDH isoenzymes, lactate, and pyruvate as a result of feeding low fat diets to healthy men and women.

A study was conducted to evaluate the effects on blood lipids and lipoproteins of feeding 21 healthy volunteers, 40-60 yr old, foods commonly eaten in the United States for two 40-day periods. Activities of lactate dehydrogenase (LDH) and LDH isoenzymes, lactate, and pyruvate were monitored. Results showed that LDH activity was significantly lower in all subjects at the end of the 25% fat-calorie period (period I) than at the beginning of the study, but rose above initial levels at the end of the 35% fat-calorie period (period II). While total LDH fell during period I, relative activity of M type subunits of LDH rose significantly in relation to H type in both sexes. This rise is probably indicative of an increase in glycolytic activity as a consequence of the increased intake of dietary carbohydrate. In period I, lactate and pyruvate decreased significantly in males (pyruvate greater than lactate) but not in females. Values for males returned to near initial levels in period II. The ratio of lactate/pyruvate was elevated in both sexes after period I. The greater change in pyruvate relative to lactate with increased dietary carbohydrate suggests increased Krebs Cycle activity. There was a statistically significant positive correlation between lactate, pyruvate, and serum triglyceride for males after they ate the 25% and 35% fat-calorie diets and for females after they ate the 35% fat-calorie diet, but not between lactate, pyruvate, and serum cholesterol for either sex.

Adult↗
PubMed1975

Metabolic effects of propranolol in thyrotoxicosis. I. Nitrogen, calcium, and hydroxyproline.

The effect of propranolol on the hypermetabolism of thyrotoxicosis was investigated in eight subjects with diffuse toxic goiter. After equilibration on a constant nitrogen, calcium, and hydroxproline intake, nitrogen balance was determined before and during propranolol therapy prior to subtotal thyroidectomy and compared to similar data obtained in seven of the patients following surgically induced euthyroidism. Propranolol administration was associated with clinical amelioration and a rapid, statistically significant, improvement in nitrogen retention. A slight additional improvement in retention was noted in the postoperative euthyroid state. Oxygen consumption, measured serially in four patients, was not significantly changed by propranolol. Urinary loss of calcium, phosphorus, and hydroxyproline was unaffected by propranolol, but excretion of these substances was sharply reduced in the subjects restudied postoperatively. These data offer a evidence of a previously unreported nitrogen sparing effect of oral propranolol during its short-term administration in thyrotoxic man.

Adult↗