Biomedical subjects

G Chune

Publications and source records attributed to G Chune.

5 recordsLinked to original sources

PubMed1992

Effective portal insulin delivery with enzyme-protected capsules in pancreatectomized pigs.

1. Plasma concentrations of insulin, C-peptide, glucagon and glucose were measured in surgically pancreatectomized pigs given insulin into the colon directly and in enteric peptidase-resistant (methacrylic acid copolymer-encapsulated) form. 2. Following introduction of insulin-containing capsules, plasma insulin concentration rose from 2.7 +/- 0.1 microU/ml to 110.9 +/- 51.9 microU/ml in the portal vein, and from 2.6 +/- 0.1 microU/ml to 26.9 +/- 7.3 microU/ml in the systemic circulation. Corresponding portal and systemic values after direct (non-encapsulated) insulin instillation were 28.2 +/- 15.9 microU/ml to 44.8 +/- 13.0 microU/ml and 7.5 +/- 2.6 microU/ml to 15.2 +/- 2.5 microU/ml respectively. Insulin concentrations peaked at 75 min in the group as a whole and between 60-90 min in individual animals. Absorption was most pronounced in pigs given aprotinin (a trypsin inhibitor) with insulin. 3. Plasma portal vein glucose concentrations fell from 76.2 +/- 8.9 mg/dl to 31.1 +/- 3.2 mg/dl 150 min after encapsulated insulin administration. Corresponding systemic glucose levels were 84.5 +/- 11.0 mg/dl and 37.0 +/- 1.4 mg/dl. 4. Colonic administration of insulin in methacrylic acid coated capsules results in peak portal and systemic insulin levels 60-90 min after administration. Co-administration of aprotinin enhances the fraction of insulin absorbed.

Animals↗

PubMed1992

Nelson's syndrome.

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Adrenocorticotropic Hormone↗

PubMed1991

Corticotropin releasing hormone and gonadotropin secretion in physically active males after acute exercise.

Plasma concentrations of corticotropin releasing hormone (CRH) and the serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, adrenocorticotropic hormone (ACTH) and cortisol were measured in seven physically active males after acute exercise on a treadmill using the Bruce protocol. Measurements were made in the basal pre-exercise state, immediately after exercise, and at 30-min intervals for 3 h after exercise. Serum LH concentrations declined following exercise reaching nadir values between 60 and 180 min after exercise (90 min post exercise in the group). The nadir values in individual volunteers were significantly lower than both the baseline and post-exercise levels. This fall in serum LH concentration appeared to follow a slight but significant elevation of the plasma concentration of CRH which reached peak levels when measured immediately post exercise. Plasma ACTH concentrations paralleled the rise in CRH, but fell to undetectable levels of below 13.8 nmol.l-1 (less than 5 ng.l-1) 60 min after exercise. Plasma cortisol concentrations peaked approximately 30 min after the rise in ACTH, after which they gradually declined to baseline levels. Plasma testosterone concentrations paralleled the concentrations of LH. The data suggest that CRH, on the basis of its previously described gonadotropin-depressant property, may be the hormone involved in the exercise-mediated decline in serum LH. Alternatively, some as yet unidentified factor(s), may be involved in producing the altered concentrations of both LH and CRH.

Adrenocorticotropic Hormone↗

PubMed1991

Inhibin and gonadotrophin secretion in physically active males after acute exercise.

Serum concentrations of luteinizing hormone (LH) follicle stimulating hormone (FSH), testosterone and inhibin were measured in six physically active male volunteers after heavy exercise on a treadmill. Hormone measurements were made before exercise, immediately after exercise and at 30-min intervals for 3 h after exercise. Serum concentrations of LH fell after exercise reaching nadir values between 60 and 180 min post-exercise. The nadir value of LH for the group as a whole occurred 90 min after exercise. Serum testosterone concentrations paralleled the changes in LH concentrations. Serum FSH and inhibin concentrations did not show any appreciable change from baseline values. The data suggest that acute exercise does not significantly lower serum concentrations of FSH or inhibin. Whether repetitive and prolonged heavy exercise, as in competitive runners, produces alterations in serum inhibin concentrations remains to be determined.

Adult↗

PubMed1991

Concentrations of volume-regulatory hormones after acute exercise in physically conditioned males.

Plasma renin activity and plasma concentrations of atrial natriuretic peptide (ANP), arginine vasopressin (AVP) and aldosterone (Aldo) were determined in six physically conditioned male volunteers and five unconditioned volunteers who served as controls. All volunteers were subjected to acute exercise for 15 min or until exhaustion. In the conditioned volunteers, the plasma concentrations of all hormones did not change when compared with pre-exercise values measured immediately after and 60 min after exercise. Similarly, plasma renin activity (PRA) after exercise was unchanged when compared with pre-exercise levels. In contrast, the unconditioned volunteers showed elevation of the plasma concentrations of AVP, and Aldo. PRA also increased in the unconditioned volunteers, but plasma ANP concentrations were not significantly different from base-line pre-exercise levels. These data suggest a decrease in central volume with exercise in the unconditioned individuals, which probably does not occur in the conditioned individual because of adaptive mechanisms. The data also suggest that in the physically conditioned individual, significant atrial distention with resultant release of atrial natriuretic peptide does not occur, or alternatively, that significant atrial distention in these subjects fails to produce the expected release of atrial natriuretic peptide. In the unconditioned individual, the postulated decrease in effective central volume following exercise would not be expected to trigger any rise in ANP.

Adult↗