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Biomedical subjects

D Ayalon

Publications and source records attributed to D Ayalon.

At least 91 records · Page 5Linked to original sources
PubMed1978

Is the fat breath test effective in the diagnosis of fat malabsorption and pancreatic disease?

An attempt was made to evaluate the diagnostic effectiveness of the 14CO2-tripalmitin breath test in the screening or diagnosis of fat malabsorption. The differential absorption of 14C-tripalmitin and palmitic acid was evaluated in the diagnosis of pancreatic insufficiency. 24 controls, 13 patients with steatorrhea and 6 with pancreatic disease (4 of them with sufficiency) were studied. 81 breath tests were performed using 75 ml sour cream as a carrier. In 11 cases the 14C-tripalmitin test was repeated using 27 g corn oil as carrier. Both the 14C-tripalmitin and 14C-palmitic acid breath tests failed to provide any discrimination between normals and patients with fat malabsorption. Variation in type and amount of the carrier fat did not alter these results. 14C-tripalmitin absorption was distinctly abnormal in the patients with pancreatic insufficiency. The differential absorption of 14C-tripalmitin and 14C-palmitic acid provided an even better separation between patients with and without pancreatic disease. In contrast to some other investigators we did not find the 14C-tripalmitin and/or palmitic acid breath tests useful in the diagnosis or screening of fat malabsorption. These tests appear promising in the diagnosis of pancreatic disease.

Adolescent↗
PubMed1977

Immunoreactive insulin in serum and seminal plasma of diabetic and nondiabetic men and its role in the regulation of spermatozoal activity.

Concentrations of immunoreactive insulin (IRI) and, in some cases, testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were measured in serum and seminal plasma (SP). IRI levels were usually higher in SP. They were unaffected by masturbation; circulating testosterone, LH, and FSH levels were also unaffected. The IRI concentration was higher in the second (vesicular) fraction of split ejaculates. Semen quality was unrelated to IRI in SP in normal and diabetic (chlorpropamide-maintained) men. The addition of insulin in vitro to washed spermatozoa from diabetic and nondiabetic men had no effect on oxygen and glucose uptake or on lactate production and spermatozoal motility. Furthermore, administration of L-arginine to infertile men for 3 months (4 gm/day) was followed in four of seven men by significant increases in IRI concentrations in blood and SP. However, neither semen quality nor fertility was improved.

Adult↗
PubMed1977

Gonadotrophin release in ovariectomized patients. I. Suppression by clomiphene or low doses of ethinyl oestradiol.

Administration of clomiphene citrate (150 mg/day) for 5 days to twenty-four ovariectomized patients and seven normal female patients evoked a significant release of FSH and LH in the normal control group and suppressed the gonadotrophin secretion in the castrated patients. A similar suppressive effect on gonadotrophin secretion was noted in eight ovariectomized patients treated for 10 days with low doses (50 microgram/day) of ethinyl oestradiol. It is suggested that in the ovariectomized hypoestrogenic patients, clomiphene acted as an oestrogen, suppressing by a negative feedback action gonadotrophin release in a way similar to ethinyl oestradiol. In the normal control group with an adequate steroid environment, clomiphene acted (probably at the hypothalamic level) as an oestrogen antagonist and stimulated gonadotrophin secretion. In view of our findings, it seems as if the ability of anovulatory patients to respond to clomiphene treatment by increased gonadotrophin secretion depends upon the absolute concentration of the compound in the different organs and by the quantitative relation of clomiphene to the endogenous oestrogens.

Adult↗
PubMed1977

Acute effect of delta1-tetrahydrocannabinol on the hypothalamo-pituitary-ovarian axis in the rat.

Administration of delta1-tetrahydrocannabinol (delta1-THC), the principal psychoactive ingredient of cannabis, to proestrous rats (2 mg/rat, i.p., between 12.00 and 16.00 h) suppressed the proestrous rise in the plasma levels of LH, FSH and prolactin (Prl) and caused a 24 h delay in ovulation. Furthermore, the increased accumulation of prostaglandins of the E-type (PGE) in the ovaries, normally seen on the evening of proestrus, was prevented. Earlier (08.00-10.30 h) or later (18.00 h) administration of the drug on the day of proestrus was only partially effective in inhibiting ovulation. The suppressive effects of delta1-THC on ovulation and gonadotropin secretion were prevented by administration of gonadetropin releasing hormone (GnRH, 0.2 microgram/rat) 1 h after the drug, indicating that the central action of delta1-THC was exerted on the hypothalamus and not on the pituitary gland. Administration of ovine luteinizing hormore (oLH, 2.5 microgram/rat at 16.30 h on the day of proestrus restored ovulation and ovarian PGE accumulation in Nembutal-treated rats, but not in delta1-THC-treated rats; higher doses of oLH (5-10 microgram/rat) reversed the action of delta1-THC on these two parameters.

Animals↗
PubMed1976

Weight loss in patients treated long-term with levodopa. Metabolic aspects.

Seven aged Parkinsonian patients treated with levodopa (average dose 3-4 g daily for 1-3 years), showed a considerable weight loss. They were compared to two control groups of elderly and young volunteers after levodopa stimulation and after oral glucose tolerance tests. It was found that after levodopa administration the plasma free fatty acids, glucose, growth hormone and cortisol were significantly higher in the Parkinsonian group than in the young control group and only slightly higher than in the aged control group. It was also found that the serum insulin was significantly higher in Parkinsonian patients than in the aged control group. We think that the metabolic disturbances found in Parkinsonian patients are not solely due to levodopa administration but may be due to ageing processes. We suggest that weight loss in the older Parkinsonian patients treated over long periods with high doses of levodopa, is due to the enhancement of the lipolytic activity of the ageing fat cells caused by high levels of circulating insulin.

Age Factors↗
PubMed1975

Malignant metastatic insulinoma treated with streptozotocin.

A patient with metastatic insulinoma who suffered from severe hypoglycaemic attacks was treated with 7-5 g of streptozotocin (Upjohn). Shortly after the start of treatment, the hypoglycaemic attacks ceased; fasting blood glucose levels and serum immunoreactive insulin values returned to normal upon completion of the treatment. Two years after treatment, the patient is well and active and has not had any attacks. The oral glucose tolerance test and tolbutamide stimulation test now show serum immunoreactive insulin excretion patterns similar to those seen in diabetics.

Adenoma, Islet Cell↗
PubMed1975

Under-responsiveness of growth hormone secretion after L-dopa and deep sleep stimulation in obese subjects.

Plasma levels of glucose, free fatty acids and free 11-hydroxycorticosteroids, and serum levels of immunoreactive human growth hormone (HGH) and immunoreactive insulin were determined before and after L-dopa stimulation in 18 obese and six normal-weight subjects. A blunted response of HGH was found in the obese subjects who received 0.5 g L-dopa, but when the dose was doubled, a normal response was obtained in 7 of 13 of the obese subjects. No significant fluctuations in free 11-hydroxycorticosteroid, glucose or insulin levels were found in the obese and normal-weight groups and no increase in HGH was seen in the obese group after the subjects had been asleep for 90 min. In the obese subjects, the blunted response of HGH to stimulation with 0.5 g L-dopa and the lack of HGH increase during sleep are attributed to hypothalamic under-responsiveness, which is considered a basic disturbance in obesity.

11-Hydroxycorticosteroids↗