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M A Permutt

Publications and source records attributed to M A Permutt.

158 records · Page 9Linked to original sources
PubMed1976

The effect of marijuana on carbohydrate metabolism.

The authors observed the effect of marijuana on carbohydrate metabolism in fed and fasting states in chronic marijuana users. They found no hypoglycemia in 7 patients who were given marijuana after fasting for 24-72 hours. They also found no significant difference in carbohydrate tolerance and no hypoglycemia during an oral glucose tolerance test in 10 patients who smoked placebo or marijuana on alternate days. They conclude that marijuana has no effect on carbohydrate metabolism in the fed or the fasted state in well-nourished chronic marijuana users.

Adult↗
PubMed1976

Effects of carbohydrate restriction on the hypoglycemic phase of the glucose tolerance test.

The effects of carbohydrate (CHO) restriction on the hypoglycemic phase of the glucose tolerance test were studied in ten normal subjects. The mean nadir plasma glucose was 64 +/- 4 mg/dl (x +/- SEM) for the control test, and 48 +/- 4 mg/dl (P less than 0.01) after 3 days of an isocaloric low CHO diet. Following the low CHO diet, six of ten subjects had a nadir plasma glucose less than 50 mg/dl, and five of these six had mild symptoms of hypoglycemia compared to no biochemical or symptomatic hypoglycemia during the control test. Hormone secretory patterns under the two experimental conditions were measured. CHO restriction produced a significant decrease in early insulin release followed by excessive insulin relative to the control test at 3-4 h of the test. Glucose ingestion produced a depression of plasma, glucagon from fasting levels during the control test, which was impaired following CHO restriction. Plasma growth hormone and cortisol responses were not different under the two experimental conditions. These studies demonstrate that CHO restriction followed by concentrated CHO ingestion produces hypoglycemia in normals. They emphasize the need to consider dietary history in evaluation of hypoglycemia. CHO restriction may provide a useful model for further study of the mechanisms of hypoglycemia.

Adult↗
PubMed1975

Effect of adrenergic agents on postgastrectomy hypoglycemia.

Reactive hypoglycemia was documented in ten postgastrectomy patients by a control oral glucose tolerance test (OGTT). Nine patients experienced nausea, flushing, and fatigue during the first hour of the test. Neuroglycopenic or adrenergic symptoms of hypoglycemia occurred in eight patients two to five hours after oral glucose. The oral administration of phenylephrine elixir, 15 mg., thirty minutes before a repeat OGTT, significantly raised thelowest plasma glucose from 37.5 +/- 2.8 mg./dl. to 45.2 +/- 3.8 mg./dl. (p less than 0.05) but did not affect the occurrence of either the early or the late symptoms. In contrast, propranolol, 10 mg., raised the lowest plasma glucose from 37.5 +/- 2.8 mg./dl. to 57 +/- 5.2 mg./dl. (p less than 0.02) and prevented the occurrence of early and late symptoms. Neither peak nor total plasma insulin levels were affected by either drug. The rate of glucose utilization, as determined by intravenous glucose tolerance tests, did not significantly change after the oral administration of either drug. It is concluded that propranolol ameliorated the symptoms and chemical hypoglycemia after oral glucose and merits more detailed study as a long-term therapy for this disorder.

Adult↗
PubMed1975

Insulin biosynthesis and secretion.

Studies are presented which support the concept that a cell membrane localized glucoreceptor system is involved in the insulin secretory response to glucose and that the specific stimulation of insulin synthesis by glucose reflects effects at both the transcriptional and posttranscriptional level. After 48 hours of fasting the insulin secretory response to glucose is markedly reduced. This reduction is overcome by 24 hours of refeeding carbohydrate, but notprotein or fat, and is blocked by refeeding in the presence of an inhibitor of RNA synthesis. Although these studies clearly demonstrate an inducible glucoreceptor system, they do not permit conclusions regarding either its composition or location in the beta-cell. Phloridzin, a glycoside with a high affinity for glucose-carrier systems in plama membranes, stimulated basal insulin secretion sixfold. A large number of plant lectins were tested for ability to stimulate insulin release from isolated islets, and only mushroom lectin did so. The lectin concentration producing half-maximal hormone releaseis 3 x 10-7, a value in good agreement with the dissociation constant forlectin binding. Glucose stimulated insulin sythesis in isolated rat islets was determined to be partially inhibited by actinomycin D. The posttranscriptional effect was determined to be increased initiation of total islet mRNAas well as proinsulin mRNA. To futher quantitate the effect of glucose on proinsulin mRNA, immunoprecipitation of proinsulin synthesizing polysomes was accomplished. It appeared that proinsulin is synthesized on a mRNA accommodating six to eight ribosomes, and the size of the proinsulin mRNA is 10-11 S on sucrose gradients. This unexpectedly large size of the proinsulin mRNA is discussed.

Animals↗
PubMed1972

Insulin biosynthesis: studies of Islet polyribosomes (nascent peptides-sucrose gradient analysis-gel filtration).

A method is described for separation of polyribosomes from as few as 25 isolated Islets of Langerhans, representing about 250 mug of pancreatic tissue. Islets are labeled with [(3)H]leucine and polysomes are isolated with liver polyribosomes, which serve as carrier and inhibitor of ribonuclease activity. Islets incubated at 37 degrees C for 45 min in 15.5 mM glucose, then pulsed with [(3)H]leucine, incorporated about 2-3 times more label into nascent peptides on islet polysomes than islets incubated in 2.8 mM glucose. Sucrose gradient analysis of the labeled polysomes indicated that raising the glucose concentration preferentially stimulated synthesis of peptides on trisomes and larger polyribosomes. Islets incubated with [(3)H]leucine for 15 min incorporated two-thirds of the label into proteins on membrane-bound polysomes. At least 85% of the proinsulin synthesis during this time occurs on membrane-bound polysomes.

Animals↗
PubMedDate not supplied

Insulin gene structure and function: a review of studies using recombinant DNA methodology.

This review focuses on recent advances in molecular biology as they pertain to the insulin gene and diabetes mellitus. The structure of the human insulin gene is examined, and factors related to its normal functioning in the beta cells of the pancreas are explored. DNA polymorphisms near the insulin locus and their relationship with certain types of diabetes are considered, as are recently characterized human insulin gene mutations. Events in animal models for diabetes that reflect altered insulin gene expression are discussed and the potential application of gene therapy in human diabetes is examined. Recombinant DNA methodology holds great promise as a tool for providing better understanding of the causes of diabetes and potential curative treatment.

Animals↗