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Biomedical subjects

M M Martin

Publications and source records attributed to M M Martin.

At least 55 records · Page 3Linked to original sources
PubMed1989

Two-dimensional and Doppler echocardiographic evaluation after arterial switch repair in infancy for complete transposition of the great arteries.

The most recent postoperative echocardiographic examinations of all children who underwent arterial switch repair of transposition of the great arteries from August 1985 to December 1987 were reviewed. The patients included 35 children whose age at operation was 12 +/- 16 days and whose weight was 3.6 +/- 0.4 kg. Thirty-three patients are alive and well; 1 died intraoperatively and 1 died immediately postoperatively. The time of the follow-up echocardiographic examination ranged from 1 day to 2.5 years (mean 9.2 months) with 11 patients examined greater than 1 year after surgery. Complete examination of the repair site was possible in all patients. Echocardiographic visualization of distortion of the great arteries at the suture lines was seen in all patients; however, Doppler evidence of hemodynamically significant obstruction at the repair site was uncommon. On Doppler examination in the surviving 33 patients, 16 had no supravalvular pulmonary stenosis and 14 had mild to moderate supravalvular pulmonary stenosis with peak systolic pressure gradients ranging from 16 to 56 mm Hg (mean 31). Three patients had severe supravalvular pulmonary stenosis and peak systolic pressure gradients of 66, 74 and 77 mm Hg (2 have had reoperation, 1 is awaiting surgery). On Doppler examination, 4 patients had mild supravalvular aortic stenosis with peak systolic gradients ranging from 10 to 29 mm Hg. Doppler gradients were confirmed in 10 patients who had catheterization 12 +/- 3 months after surgery. Three patients had mild pulmonary regurgitation by Doppler examination, 5 had mild aortic regurgitation, 4 had mild tricuspid regurgitation and 2 had mild mitral regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography↗
PubMed1988

Obstruction to left coronary artery blood flow secondary to obliteration of the coronary ostium in supravalvular aortic stenosis.

Supravalvular aortic stenosis is characterized by obstruction of the left ventricular outflow tract distal to the aortic valve, and may result in diminished coronary artery blood flow. This report describes the cases of 2 patients in whom obstruction to left coronary artery flow was caused by obliteration of the coronary ostium itself. This mechanism differs from the more commonly recognized cause--valve leaflet adhesion to the obstructing ridge of aortic tissue. The coronary artery obstruction found in these 2 patients required direct enlargement of the left coronary ostium in both. This mechanism of impaired coronary artery flow deserves emphasis, as traditional methods of extended patch aortoplasty may fail to relieve the coronary ostial narrowing.

Aorta↗
PubMed1986

The anti-sickling drug lawsone (2-OH-1,4-naphthoquinone) protects sickled cells against membrane damage.

The ability of an anti-sickling drug lawsone, 2-OH-1,4-naphthoquinone, and two related compounds to inhibit the haematoporphyrin-sensitised photohaemolysis of normal and sickle cell erythrocytes has been investigated. The compounds appear to protect the erythrocyte membranes by reaction with transient oxidative species. Differential effects between normal and sickle cells are shown and these are attributed to the different membrane composition of irreversibly sickled erythrocytes. This report describes a possible basis for the decreased formation of irreversibly sickled cells in the presence of lawsone.

Erythrocyte Membrane↗
PubMed1986

Testosterone treatment of constitutional delay in growth and development: effect of dose on predicted versus definitive height.

The outcome of treatment in 3 groups of boys with constitutional delay in growth and development given monthly intramuscular injections of testosterone enanthate 200 mg (22 subjects) 100 mg (10 subjects) and 50 mg (12 subjects) was compared with the outcome in a control group (14 subjects) without treatment. The 4 groups were similar in chronological age, height, height age, bone age, height age/bone age ratio, pubertal development and had similar predicted adult heights. All treated subjects achieved an excellent growth response with growth velocities reflecting androgen dose. Bone age advanced commensurate with height age in all the treated groups and delta height age/delta bone age ratios at the end of therapy did not differ significantly. Nor was there a significant difference in the height prediction by the RWT method before and at the end of treatment. However, the year following treatment, growth velocities reversed so that those who received the largest steroid dose and had grown the fastest, decelerated the most and eventually ended up significantly shorter than their predicted adult height. In contrast the control group and those treated with smaller doses of testosterone achieved their predicted heights. The present study confirms that large doses of androgens compromise adult height and are contraindicated in the treatment of constitutional delay in growth and development. Testosterone enanthate 50 mg/mo did not affect predicted adult height adversely, but to the contrary, permitted it to be fully realised. The data caution against drawing conclusions based on changes observed during androgen therapy in the absence of extended follow-up.

Adolescent↗
PubMed1977

Familial nephrosis, nerve deafness, and hypoparathyroidism.

Two male siblings with nephrotic syndrome, nerve deafness, and hypoparathyroidism are described. Each child, one at five years of age and the other at eight years, died in renal failure. At autopsy the parathyroid glands were absent in one child and hypoplastic in the other one. Two twin male siblings presented with similar findings and died at the age of three years. At autopsy their parathyroid glands were fibrotic, and glomerular basement membranes were thickened. This may be the first recorded association of familial nephrosis, nerve deafness, and hypoparathyroidism. The mode of transmission is compatible with autosomal recessive inheritance.

Child, Preschool↗
PubMed1977

Effect of large amounts of vitamin E during pregnancy and lactation.

The effects of excessive intake of vitamin E during gestation and lactation on female rats and their progeny were studied. Pregnant rats receiving large doses of vitamin E (22.5 to 2252 mg/kg per day) had larger livers, higher levels of lipids and vitamin E in plasma, and higher concentrations of vitamin E in the livers than did controls. These deviations from normal were not, however, observed for all levels of supplementation. No obvious teratogenic effects were observed in the newborn young of the vitamin E-supplemented rats. Some eye abnormalities were seen in the older pups of rats given extremely high amounts of the vitamin. The survival rate, weight of the pups, and litter size were unaffected. However, the pups of the mothers who had received 500 mg of vitamin E per day (2252 mg/kg per day) during gestation and lactation had a much higher concentration of vitamin E in their livers and plasma than did controls. This study also confirmed the observation that vitamin E transfer across the placenta is negligible and that mammary transfer of this vitamin is quite efficient.

Animals↗
PubMed1976

Influence of castration and testosterone replacement on hypothalamic tyrosine hydroxylase activity in the rat.

Hypothalamic tyrosine hydroxylase (TH) activity of castrate rats is modulated by testosterone propionate (TP) in vivo. Kinetic studies revealed that both Vmax and Km were virtually unaltered for substrate tyrosine in the presence of an excess of DMPH4 cofactor. TP replacement to castrate rats increased the Km for added DMPH4 cofactor, while Vmax decreased. These results suggest that TP decreases TH activity of castrate rats by inhibiting the enzyme-reduced pteridine cofactor complex.

Animals↗
PubMed1976

The syndromes of insulin resistance and acanthosis nigricans. Insulin-receptor disorders in man.

In six patients with acanthosis nigricans variable degrees of glucose intolerance, hyperinsulinemia and marked resistance to exogenous insulin were found. Studies of insulin receptors on circulating monocytes suggest that the insulin resistance in these patients was due to a marked decrease in insulin binding to its membrane receptors. When these patients were fasted, there was a fall in plasma insulin but no increase in insulin binding, suggesting that the receptor defect was not secondary to the hyperinsulinemia. The clinical features shared by these cases and several similar ones previously reported may be divided into two unique clinical syndromes: Type A, a syndrome in younger females with signs of virilization or accelerated growth, in whom the receptor defect may be primary, and Type B, a syndrome in older females with signs of an immunologic disease, in whom circulating antibodies to the insulin receptor are found.

Acanthosis Nigricans↗
PubMed1976

Continuous low-dose infusion of insulin in the treatment of diabetic ketoacidosis in children.

Twelve diabetic children--eight in ketoacidosis, three with insulin refractory hyperglycemia, and one postoperative patient--were treated with continuous, low-dose, intravenous infusion of insulin. The eight ketoacidotic children with a mean serum glucose concentration on admission of 631 mg/dl and bicarbonate value of 6.8 mM/1 were given regular insulin, 0.1 U/kg, slowly by bolus injection followed by a sustaining infusion of 0.1 U/kg/hour. Plasma glucose concentration fell at a mean rate of 82 mg/dl/hour. Euglycemia with concomitant improvement in the metabolic disorder was achieved with a mean dose of insulin, 0.68 U/kg, given over four to 10 hours. Mean plasma insulin in those children who had not previously received insulin was 55 muU/ml, well within the normal physiologic range. Growth hormone and serum triglyceride levels, low initially, rose with insulin therapy before returning to control values. Continuous low-dose insulin infusion is simple, safe, and effective, avoids confusion and empiricism, and appears to be the method of choice for the treatment of diabetic ketoacidosis or insulin resistance.

Adolescent↗