Search PubMed⌕ Search

Biomedical subjects

A Lapidot

Publications and source records attributed to A Lapidot.

98 records · Page 6Linked to original sources
PubMedDate not supplied

Effect of acute insulin-induced hypoglycemia on fetal versus adult brain fuel utilization, assessed by (13)C MRS isotopomer analysis of [U-(13)C]glucose metabolites.

Tight glycemic control during diabetic pregnancy has been shown to significantly reduce the occurrence of congenital malformations and other effects of maternal diabetes on the offspring. However, intensive insulin therapy often causes recurring acute maternal hypoglycemia, which has been found to be harmful to the developing fetus, although the mechanisms involved are not clear. The aim of our work was to study the effect of acute insulin-induced maternal hypoglycemia on glucose metabolism in the fetal brain. To this end, near-term pregnant New Zealand rabbits were rendered hypoglycemic, and [U-(13)C]glucose was infused into maternal circulation. The metabolic fate of the (13)C-labeled glucose was then studied in fetal brain extracts by (13)C NMR isotopomer analysis, together with conventional biochemical assays of glucose and lactate levels in both plasma and brain. For comparison [U-(13)C]glucose was also administered to insulin-induced hypoglycemic young adult rabbits. Our results showed that while plasma glucose levels were significantly reduced (approximately 70%) relative to controls, no changes in cerebral glucose levels could be detected. Lactate levels were found to be significantly decreased in hypoglycemic fetal plasma and brain. No differences in lactate levels between control and hypoglycemic young rabbit plasma and brain were observed. These differences were attributed to the utilization of lactate as an energy substrate in the fetal brain, but not in the adult brain. Higher relative (13)C enrichments of most glucose metabolites, except lactate, in the hypoglycemic fetal and young rabbit brains, observed by (13)C NMR, stem from reduced endogenous plasma glucose pools, thereby diluting the labeled glucose to a lower extent. The relative glucose (or glucose-derived lactate) flux via the pyruvate carboxylase and pyruvate dehydrogenase pathways (PC/PDH ratio) was not altered under hypoglycemic conditions in the fetal brain for both glutamine and glutamate, but significantly increased in the adult brain for both glutamine and glutamate. The presented data indicate the ability of the fetal brain to maintain energy metabolism during acute hypoglycemia, via lactate utilization. The increase in the adult PC/PDH ratio was suggested by us to stem from increased PC activity, in order to replenish TCA cycle intermediates.

Amino Acids↗
PubMedDate not supplied

Primary oat-cell carcinoma of head and neck.

Summary--A case of primary oat-cell carcinoma of the larynx in a 68-year-old white female is described, bringing to a total of three the reported cases in the world literature. The tumor is highly malignant and notorious for the speed with which it metastasizes. Treatment should be aggressive from the beginning. We believe that even for a localized tumor of this kind, a minimal procedure should be widefield laryngectomy with elective radical neck dissection even if clinically, nodes are not palpable. Since the tumor is highly radiosensitive, radiotherapy should be used postoperatively.

Aged↗
PubMedDate not supplied

Eustachian tube bypass: experimental evidence for total eustachian tube substitution.

Several preliminary reports have appeared in the medical literature in respect to eustachian tube substitution since Zollner first described his inability to open the obstructed eustachian tube. These procedures have the disadvantage that the distal end of the eustachian tube subsitute is inaccessible by other than another operation. This paper is follow-up report to our clinical experience. The purpose of the experiment was to determine whether the middle ear was ventilated by the tympano-oropharyngeal substitute eustachian tube and whether ascending infection occurred. Fourteen ears underwent eustachian tube substitution. The natrual eustachian tubes of these ears were obliterated three to five months after eustachian tube substitution had been performed. The animals were killed three to four months after obliteration of the natural eustachian tubes. Studies of the decalcified sections showed an absence of infection in six of the ears, with mild to severe inflammation in the rest of the specimens.

Animals↗
PubMedDate not supplied

Dynamic parameters of glycine metabolism in diabetic human pregnancy measured by [15N]glycine and gas chromatography-mass spectrometry.

This study presents kinetic parameters of glycine metabolism during pregnancy and the influence of fuel availability in the maternal compartment. The effect of gestational diabetes mellitus (diet treated) and pre-gestational diabetes mellitus (diet and insulin treated), accompanied by increased fetal growth on [15N]glycine kinetic parameters, compared to normal pregnancies with normal fetal growth, has been determined. This process was measured by administration of a single-dose of [15N]glycine to post-absorptive normal and diabetic pregnant women during the third trimester of pregnancy. Gas chromatography-mass spectrometry was used to determine the 15N enrichment of plasma glycine, and to calculate the pool sizes, turnover rate constants, fluxes and metabolic clearance rates. Glycine pool sizes in pre-gestational diabetes were significantly larger than those in normal pregnancy and gestational diabetes. Glycine turnover rate constants and metabolic clearance rates were not significantly different between the normal pregnant women and the two diabetic groups of pregnant women. Glycine fluxes were significantly higher in the pre-gestational diabetic pregnant women than in gestational diabetes and normal pregnancy. The pre-gestational diabetic pregnant women delivered fetuses with higher birth weights than the other two groups.

Adult↗
PubMedDate not supplied

Effects of streptozotocin-induced diabetes on drug metabolism in rats.

The metabolism of salicylic acid was investigated in male normal and diabetic rats. The results showed a decrease in urinary excretion of salicylic-glucuronic acid in diabetic animals and this decrease is statistically significant (P less than or equal to 0.01), while the urinary excretion of salicyluric acid in the diabetic group was higher than in controls and statistically significant (P less than or equal to 0.001). There was no marked difference between normal and diabetic rats in total urinary excretion of salicylic acid and metabolites.

Animals↗