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Biomedical subjects

M A Sperling

Publications and source records attributed to M A Sperling.

At least 109 records · Page 6Linked to original sources
PubMed1975

Effects of oral alanine feeding on blood glucose, plasma glucagon and insulin concentrations in small-for-gestational-age infants.

The effects of oral alanine feeding on glucose homeostasis were evaluated in 21 infants who were small for gestational age and 26 who were appropriate for gestational age. In the first 24 hours, basal plasma alanine concentrations were higher in the former. Oral alanine feedings produced a significant rise over baseline levels of plasma alanine and glucagon concentrations in both groups. The blood glucose and plasma insulin concentrations also increased significantly in infants who were appropriate but not in those who were small for gestational age. At 25 to 96 hours of age, plasma glucagon, insulin and blood glucose concentrations did not change after the alanine feeding in either group. These data indicate that in the normally nourished infant (appropriate forgestational age), gluconeogenic amino acid (alanine) enhances hepatic glucose output. This phenomenon is not observed in the mainourished infants (small for gestational age), a point that may reflect decreased glycogen stores and ineffective gluconeogenic enzyme system in such infants.

Administration, Oral↗
PubMed1975

Effect of adrenergic blockade on glucagon and growth hormone secretion in normal and diabetic children.

Studies were conducted in four normal and six diabetic children to assess the role of adrenergic blockade on basal and arginine-stimulated growth hormone and glucagon secreation. Each subject had, on three separate occasions, infusion of arginine alone or in conjunction with alpha (phentolamine) or beta (propranolol) adrenergic blockade. Clinically, there was evidence of adequate blockade by each agent. Basal hormone growth levels were not significantly different in the two groups (1.3 +/- 0.2 to 2.1 +/- 1.0 ng/ml in normal subjects; 3.0 +/- 1.1 to 6.0 +/- 3.1 ng/ml in diabetics (mean +/- 1 SEM)) but the peak growth hormone after arginine was significantly greater in the diabetic children than control subjects (34.3 +/- 7.2 versus 12.3 +/- 3.1); in both groups alpha-blockade suppressed the growth hormone response, whereas beta-blockade had no significant effect. Basal glucagon concentrations were similar in both groups (147 +/- 31 to 214 +/- 21 pg/ml in normal subjects; 100 +/- 20 to 124 +/- 17 pg/ml in diabetics on three different occasions) despite the coexistent hyperglycemia of the diabetics. Neither basal nor maximally stimulated glucagon secretion was significantly affected by alpha or beta blockade in the juvenile diabetic or control children. The results suggest that sympathetic overactivity via alpha receptors may contribute to the hypersecretion of growth hormone in juvenile diabetes and that the alpha or beta adrenergic receptor alone does not appear to modulate basal or arginine stimulated glucagon secretion.

Adolescent↗
PubMed1975

The effect of oral alanine on blood glucose and glucagon in the human newborn infant.

Plasma glucose, glucagon, and insulin responses to oral feedings of L-alanine were assessed in 44 healthy term infants during the first three days of life. Alanine administration produced significant increases in glucagon and glucose concentrations on day 1, but not on days 2 and 3. These increases occurred within 30 minutes (mean and SEM for glucagon, 127 plus or minus 7 to 219 plus or minus 16 pg/ml, P smaller than 0.001; glucose, 45 plus or minus 3 to 60 plus or minus 7 mg/100 ml, P smaller than 0.01) and persisted at the P smaller than 0.05 level at four hours. Responsiveness to alanine seemed to be related to the baseline blood glucose levels since constant infusions of glucose inhibited the response; These results indicate that the pancreatic islet alpha cell secretion mechanism(s) is functioning in the newborn.

Administration, Oral↗
PubMed1974

Spontaneous and amino acid-stimulated glucagon secretion in the immediate postnatal period. Relation to glucose and insulin.

The extent and significance of spontaneous glucagon secretion in the immediate postnatal period were investigated in groups of normal infants studied cross-sectionally and longitudinally. Arginine-and alanine-stimulated glucagon secretion was also studied. Plasma glucagon concentrations were correlated with prevailing glucose and insulin concentrations. The characteristic fall in blood glucose, reaching a nadir within hours of birth, was associated with a significant increase in glucagon concentration. Despite persistence of relative glucopenia, glucagon did not change appreciably between 2 and 24 h of life. A further significant elevation in glucagon concentration occurred from day 1 to day 3 of life associated with a return of glucose to euglycemic levels. In contrast to the sluggishness of pancreatic glucagon release, glucagon-like immunoreactivity rose markedly to mean levels of approximately 2,000 pg/ml after introduction of formula feeding. No significant changes in insulin levels were observed in these studies. Arginine infusion via an umbilical vein catheter into six infants within 6 h of birth elicited a brisk, almost threefold increment in glucagon concentration (from 339+/-85 to 940+/-254 pg/ml) in blood obtained from, or close to, the portal circulation. Bolus injection of alanine (1 mmol/kg) into a peripheral vein to six infants resulted in significant increments in glucagon (mean maximal, 128 pg/ml) as well as glucose and insulin. The observations suggest that spontaneous glucagon secretion may be an important factor in neonatal glucose homeostasis. Secretion seems more brisk in response to amino acid stimulation than to a falling glucose concentration.

Alanine↗