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Biomedical subjects

R W Turkington

Publications and source records attributed to R W Turkington.

At least 19 recordsLinked to original sources
PubMed1987

Reversal of severe diabetic hyperlipidemia by prandial insulinization.

Severe hyperlipidemia was nearly completely corrected in 16 diabetic patients who were treated with regular insulin at breakfast and supper. Serum cholesterol levels fell from 572 +/- 52 mg/dl to 247 +/- 10 mg/dl, and serum triglycerides fell from 6,330 +/- 820 mg/dl to 354 +/- 40 mg/dl over a 4-month period of treatment. Establishment of comparable degrees of control of the fasting blood glucose and hemoglobin A1C levels by NPH insulin did not correct the hyperlipidemia. Regular insulin timed to act for the disposal of ingested substrates appears to provide physiologic actions important in the treatment of diabetic hyperlipidemia.

Adult↗
PubMed1982

Secretion of insulin or connecting peptide: a predictor of insulin dependence of obese "diabetics".

Ninety obese "diabetic" patients, including 55 treated with insulin injection, were characterized by measurement of levels of insulin or connecting peptide of proinsulin (C peptide) induced during oral glucose tolerance testing. After reduction of body weight to ideal values, patients whose peak serum insulin levels were initially 64 microunits/mL or greater had reductions of blood glucose values from 227 +/- 24 to 122 +/- 10 mg/dL (fasting) and from 400 +/- 49 to 160 +/- 11 mg/dL (two hours postprandial); at C-peptide peaks of 6.0 ng/mL or greater, these blood glucose values fell from 244 +/- 30 to 118 +/- 12 mg/mL and from 400 +/- 51 to 160 +/- 16 mg/dL, respectively. Patients with peak values of less than 60 microunits/ml for insulin or less than 6.0 ng/mL for C peptide did not normalize the blood glucose concentration after weight loss. This critical level of insulin secretory reserve separating these groups was similar to that previously reported for avoidance of diabetic retinopathy and neuropathy. These results suggest that levels of insulin or C peptide induced during glucose tolerance testing distinguish between two types of hyperglycemic obesity-insulin-dependent diabetes mellitus and insulin-resistant obesity. Blood glucose levels alone did not identify these groups. Among consecutive hyperglycemic obese patients, 36% achieved normoglycemia by weight loss alone, including 33% of those previously treated with insulin injection.

Adult↗
PubMed1980

Depression masquerading as diabetic neuropathy.

Fifty-nine patients referred for painful diabetic neuropathy of the lower extremities were evaluated for depression and response to antidepressant drug therapy in a double-blind controlled study. All patients were found to have substantial degrees of depression during psychiatric interview and by Kupfer-Detre test scores (8.1 +/- 0.6, as compared with control values of 4.0 to 4.3 +/- 0.2). Treatment with imipramine hydrochloride or amitriptyline hydrochloride resulted in complete remission of lower extremity pains in all patients in 10 +/- 2 weeks, with concomitant relief of depression and return of depression test scores to 3.8. These results suggest that the syndrome of painful diabetic neuropathy of the lower extremities represents a depressive equivalent in a large proportion of cases and that treatment with imipramine or amitriptyline is a successful mode of therapy for such persons.

Adult↗
PubMed1978

Insulin secretion in the diagnosis of adult-onset diabetes mellitus.

The natural history of patients with glucose intolerance was observed in 334 patients during a period of 18 years. Glucose tolerance testing (100 g orally) was characterized by measurement of induced insulin secretion. Diabetic complications of retinopathy, sensory neuropathy, and renal disease developed only in the group of patients in whom the induced serum insulin peak fell below 60 mu U/ml. Preservation of an insulin secretory reserve that permitted serum insulin peaks of 60 muU/ml or greater was not associated with development of these complications or symptoms of insulin deficiency despite the presence of an equal degree of fasting hyperglycemia and glucose intolerance. A critical amount of insulin secretory reserve distinguishes between two qualitatively distinct clinical syndromes: true diabetes mellitus (the development of signs and symptoms of insulin deficiency) and the syndrome of pure resistance to insulin (signs and symptoms of hyperglycemia in the setting of adequate or excessive insulin secretion, frequently with obesity, but without diabetic complication).

Adult↗
PubMed1977

Encephalopathy induced by oral hypoglycemic drugs.

Three patients experienced severe hypoglycemic encephalopathy during oral therapy of adult-onset diabetes mellitus. Disabling residual neurological deficits were observed in two of these patients. The insidious time course of drug-induced hypoglycemia appeared to prevent patient recognition of sustained hypoglycemia. These cases indicate the need for further caution in the administration of oral hypoglycemic agents.

Brain Diseases, Metabolic↗
PubMed1976

Regulation by testosterone and serum protein of DNA synthesis in the developing epididymis of the rat.

Rates of DNA synthesis were measured as an index of cellular proliferation during the pubertal development of the rat epididymis. A highly reproducible pattern of DNA synthesis was defined by (1) a prepubertal, testosterone-insensitive peak of DNA synthesis at 25 days; (2) a dramatic decrease in DNA synthesis with the onset of puberty; (3) a major burst of testosterone-dependent synthesis peaking at 40 days in the head of the epididymis and at 40-60 days in the tail; (4) a fall to low levels as the adult organ weight was attained. An organ culture system was defined and utilized to analyse further the hormonal dependence of DNA synthesis in the epididymis. Testosterone and dihydrotestosterone failed to activate DNA synthesis at any stage of development in vitro. DNA synthesis was stimulated 100-300% by insulin at supra-physiological concentrations and by protein serum factor(s) at physiological concentrations. The serum activity was stable to heat treatment at 60 degrees C, destroyed by heating at 70 degrees C, and was present in the sera of hypophysectomized animals. These results indicate a primarily 'permissive' role for the action of testerone on DNA synthesis in the epididymis: testosterone acts to permit the expression of a developmental 'programme' of cell proliferation which is activated by specific protein(s) in serum.

Age Factors↗
PubMed1975

Gene activation during spermatogenesis.

Cell differentiation during spermatogenesis in the rat has been analyzed in terms of the formation of specific "marker" enzymes. Hyaluronidase and other acrosomal enzymes are formed in spermatids according to a highly predictable time schedule which may be termed a "molecular biological clock". The acrosomal enzymes beta-galactosidase and N-acetyl-beta-glucosaminidase exist as isoenzyme forms distinct from enzymes with similar substrate specificities in the lysosomes of precursor cells. Differentiation of spermatids thus involves the loss of gene expression for lysosomal enzymes and the activation of genes for acrosomal isoenzymes. Spermatogenesis is characterized by the sequential loss of expression of many genes, as evidenced by the loss of beta-glucuronidase in the differentiation of spermatogonia to spermatocytes, and the loss of uridine diphosphatase activity in the differentiation of spermatocytes to spermatids. The apparent absence of ornithine decarboxylase activity from spermatids suggests a dependence of these cells upon Sertoli cells for the provision of putrescine and/or spermidine. Such biochemical cooperativity among germinal cells may be necessary as the genes of spermatids are repressed and late spermatids become metabolically inactive. Spermatogenesis is also characterized by changes in the cellular content and rates of synthesis and phosphorylation of specific acidic chromatin proteins. It is hypothesized that these proteins may participate in the activation or repression of genes during spermatogenesis.

Acetylglucosaminidase↗
PubMed1975

Hormonal regulation of isoenzymes of N-acetyl-beta-glucosaminidase and beta-galactosidase during spermatogenesis in the rat.

Isoenzymes of beta-galactosidase and of N-acetyl-beta-glucosaminidase were assayed during development of rat testis and as a function of hormonal treatments. Isoenzyme 1 of beta-galactosidase was highest in specific activity in the 4-day-old testis, at a point when Sertoli cells and gonocytes were the predominant cell type. Beta-galactosidase II, previously shown to be associated with the sperm acrosome, was undetectable through the spermatocyte stage of development, but increased in specific activity during the formation of spermatids. The specific activities of isoenzymes I and II of N-acetyl-beta-glucosaminidase increased markedly in association with the formation of spermatogonia and spermatocytes, and then declined with the appearance of spermatids. Following hypophysectomy of rats at 26 days of age or in adulthood the specific activities of the lysosomal enzymes beta-galactosidase I and N-acetyl-beta-glucosaminidase I and II increased markedly, while the acrosomal beta-galactosidase II was undetectable. The normal patterns of isoenzyme distributed were restored completely by administration of LH and FSH or testosterone to hypophysectomized animals. These results thus demonstrate specific patterns of isoenzyme concentration during spermatogenesis. Formation of the acrosome in developing spermatids is associated with the induction of new forms of beta-galactosidase (isoenzyme II) and N-acetyl-beta-glucosaminidase (sperm isoenzyme). These molecules appear to be specialized forms which may participate in fertilization, and their induction is dependent upon the actions of gonadotropins or testosterone.

Animals↗
PubMed1973

Stimulation of human prolactin secretion by intravenous infusion of L-tryptophan.

Previous studies have demonstrated that the secretion of human prolactin is regulated primarily by factors that influence catecholamines of the hypothalamus. In an effort to identify other factors that may regulate prolactin secretion, the amino acid L-tryptophan, a precursor in the synthesis of serotonin, was infused into normal human volunteers. Intravenous infusion of L-tryptophan, 5-10 g over a 20 min period, but not equivalent amounts of 17 other amino acids, induced marked increases in serum prolactin concentrations in eight normal human volunteers. Increases of 20-200 ng/ml above the control level were observed with peak values at 20-45 min after initiation of the infusion. In addition, infusion of L-tryptophan was associated with decreases in serum concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyrotropin in those subjects in whom the base-line serum hormone concentration was above the lower limits of assay detectability. No consistent change was observed in serum concentrations of growth hormone, cortisol, or glucose. Four subjects with juvenile diabetes demonstrated increases in serum prolactin values comparable with those observed in healthy individuals in response to infusions of L-tryptophan. Serum prolactin values in patients with surgically induced hypopituitarism were undetectable or deficient after infusion of 10 g of L-tryptophan. In this respect, infusion of L-tryptophan was equally effective in these subjects as the standard chlorpromazine stimulation test in identifying patients with hypopituitarism, indicating that the infusion of L-tryptophan may serve as a sensitive and reliable clinical test of prolactin secretory reserve. Further studies relating to the possible mechanism of action of L-tryptophan indicated that infusion of 5-hydroxytryptophan represents a much more potent stimulus for the secretion of prolactin and that premedication with the serotonin antagonist, methysergide maleate, serves to blunt the effect of L-tryptophan on prolactin secretion. These results support the concept that the effect of L-tryptophan on the secretion of human prolactin is mediated through its conversion to serotonin and are consistent with reported experimental observations that serotonin may participate in the reciprocal regulation of prolactin and gonadotropins.

5-Hydroxytryptophan↗