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Biomedical subjects

T Fotsis

Publications and source records attributed to T Fotsis.

62 records · Page 4Linked to original sources
PubMed1981

Diet and urinary excretion of lignans in female subjects.

Lignans, a class of compounds having a 2,3-dibenzylbutane skeleton, have recently been identified for the first time in humans and animals and evidence indicating their formation by intestinal microflora has previously been established in rats and humans. In the present report the influence of diet on the biosynthesis of this new group of compounds was investigated by comparing the urinary excretion of the principal lignan, trans-2,3-bis-(3-hydroxybenzyl) -butyrolactone (enterolactone, HBBL), in 12 omnivoric and 14 vegetarian women. Young vegetarian women were found to excrete significantly greater amounts of enterolactone than omnivores, while old vegetarians excreted comparable amounts to the omnivore group. A statistically significant (P less than 0.01-0.001) correlation was found between the amount of fibre in the diet and the urinary enterolactone excretion.

Adult↗
PubMed1981

Reversed-phase C18 cartridge for extraction of estrogens from urine and plasma.

We describe a simple method for extraction of estrogens that is efficient over the whole polarity range of estrogen metabolites in urine and plasma. A small reversed-phase C18 cartridge (Sep-Pak C18, Waters Associates, Inc.) is used for this purpose. After application of the biological fluid, followed by an aqueous wash, estrogens are eluted in 3 mL of methanol. For urine the pH should be kept at 3 before the methanol elution. When estrogens are extracted from plasma, the steroid-protein interaction is counteracted by the presence of triethylammonium sulfate and D-norgestrel at pH 5. The recoveries of added 3H-labeled estrogens are essentially quantitative. The capacity of the column is high and estrogens can be extracted from large volumes of pregnancy urine without loss in the washing water. Because of the high flow rate (2 mL/min) and the small volume of methanol in which the estrogens are eluted, the whole procedure is convenient and rapid.

Chromatography, High Pressure Liquid↗
PubMed1980

Identification of 4-hydroxyestriol in pregnancy urine.

After enzymatic hydrolysis and various chromatographic steps, an estrogen metabolite behaving like 4-hydroxyestriol in capillary gas chromatography on several stationary phases was detected in pregnancy urine. The mass spectrum of its trimethylsilyl ether derivative showed the very characteristic fragmentation pattern of catechol estrogens and was found to be practically identical with that of the corresponding derivative of the reference standard. In addition, selected ion monitoring evidence of the identity of the new estrogen metabolite with 4-hydroxyestriol was obtained. It is concluded that the results confirm previous studies indicating formation of 4-hydroxylated estrogen metabolites in human tissues.

Chromatography, Gas↗
PubMed1979

Steroid absorption and enterohepatic recycling.

A short review on steroid absorption and enterohepatic recycling in man with special emphasis on contraceptive and related steroids is presented. Some new experimental data on the intestinal metabolism of steroids is described and includes further observations on the effect of antimicrobial agents on steroid hormone metabolism. Evidence is presented that plasma levels of steroids may be influenced if the intestinal microflora is altered. Some formation of biologically active steroids, like estradiol, may occur in the intestinal tract and this may have both biological and pathological consequences and may be influenced by such factors as diet and sex. It is concluded that our knowledge of the intestinal and especially, the mucosal metabolism of steroids is scanty and further studies are needed to clarify the role of the intestine and enterohepatic circulation in determining the bioavailability of natural and synthetic steroids.

Absorption↗
PubMedDate not supplied

[Increased expression of the MYCN oncogene in human neuroblastoma cells and possible, new therapeutic approaches].

Human neuroblastomas of advanced stages often display amplification with a consecutive enhanced expression of the MYCN oncogene. Enhanced MYCN expression is thought to contribute in a causative manner to the progression of neuroblastomas, but the mechanisms by which this may occur have remained unclear. By transfecting human neuroblastoma cells that display a normal MYCN expression with the human MYCN oncogene, we have generated a cell line with enhanced MYCN expression and thereby were able to compare the biological and biochemical properties of the transfected and non-transfected cells. We have demonstrated autocrine growth factors in the MYCN-transfected, but not the non-transfected, neuroblastoma cells. Identification of the primary structures of these factors may help to develop specific antagonists in order to improve the therapy of advanced neuroblastomas. Currently, this could be done by application of genistein or tumor necrosis factor. As we could demonstrate for the first time, the dietary constituent genistein is able to inhibit the proliferation of neuroblastoma cells with enhanced and normal MYCN expression, but also that of cells derived from other solid pediatric tumors. In contrast, tumor necrosis factor is able to inhibit selectively the proliferation of neuroblastoma cells with enhanced MYCN expression. We suggest that tumor necrosis factor might improve the therapy of advanced human neuroblastomas.

Animals↗