Search PubMed⌕ Search

Biomedical subjects

S Segal

Publications and source records attributed to S Segal.

At least 577 records · Page 32Linked to original sources
PubMed1977

gamma-Glutamyltranspeptidase activity in newborn rat kidney brush border.

gamma-Glutamyltranspeptidase, known to be localized in the proximal tubule cell brush border in the rat, is a membrane-bound enzyme which transfers the gamma-glutamyl moiety of glutathione or its analogue gamma-glutamyl-p-nitroanilide to an amino acid or dipeptide acceptor. Brush borders were isolated from the kidneys of newborn and adult Sprague-Dawley rats and assayed for gamma-glutamyltranspeptidase activity. There is an increase in specific activity in the brush border with maturation. Newborn and adult brush border preparations exhibit similar pH optima, substrate affinities, apparent Km values, patterns of heat inactivation, inhibition by glutathione, and migration on polyacrylamide gels. Polyacrylamide gel electrophoresis of a deoxycholate extract of brush border proteins and subsequent reaction with substrate within the gel reveal the presence of two bands, suggesting the presence of two forms of gamma-glutamyltranspeptidase in the rat kidney brush border.

Aging↗
PubMed1977

Patterns of cystine reduction by fibroblasts from normal and cystinotic children.

The possibility that the enzymatic reduction of cystine involves a multi-enzyme system led to re-evaluation of cystine reduction by fibroblasts from normal and cystinotic patients. Lineweaver-Burk plots of data with extracts of a normal cell line, representative of seven normal cell lines, under conditions of increasing cystine with variable levels of reduced glutathione (GSH) resulted in a two-limbed curve above 100 micronM cystine. Two cell lines from children with nephropathic cystinosis containing 1-6 micronmol half-cystine/g protein gave a family of curves similar to those of the normal. With six fibroblast lines containing more than 6 micronmol half-cystine/g protein, increasing cystine resulted in a family of lines without two-limbed curves. Plots of the data as activity against increasing cystine concentrations at ratios of cystine to GSH of 1:2 and 1:1 showed that two of the three lines from cystinotic subjects reduced cystine at a faster rate than the normal line. The third line from a cystinotic patient reduced cystine at a slightly slower rate when the substrate concentration in the assay was less than 80 micronM cystine. When the cystine to GSH ratio was maintained at 2:1, normal cells showed a linear increase in the rate of cystine reduction up to 100 micronM cystine, no increase in the rate between 100 micronM and 200 micronM cystine, and an increase again when the concentration of cystine was raised above 200 micronM. Such a stepwise phenomenon was absent with six cell lines containing more than 6 micronmol half-cystine/g cellular protein. A possible mechanism of control of cystine reduction is discussed.

Cell Line↗
PubMed1977

The significance of human chorionic gonadotropin in blood serum for the early diagnosis of ectopic pregnancy.

Determination of human chorionic gonadotropin (HCG) values in the serum by the radioimmunoassay technique, was performed in 23 women with suspected ectopic pregnancies. In 16 cases the values of HCG were high and the diagnosis of ectopic pregnancy was verified by laparoscopy and laparotomy. In 7 cases low HCG values were found and ectopic pregnancy was excluded. The detection of HCG in the serum was found to be an excellent tool for the early diagnosis of ectopic pregnancy, thus helping to prevent the dangerous sequelae which follow the late diagnosis of this condition.

Chorionic Gonadotropin↗
PubMed1977

Fine structure of Sertoli and Leydig cells in azoospermic human testis.

Testicular biopsy specimens taken from seven patients with azoospermia were studied by electron microscopy. We considered the possibility of a relationship between the annulate lamellae in the Sertoli cells and azoospermia. In the Leydig cells, we observed intranuclear and intracytoplasmic paracrystalline inclusions and considered their relationship with the Reinke crystalloid.

Adult↗
PubMed1977

Chorionic gonadotropin and progesterone levels in ectopic pregnancy.

It is assumed that one function of hCG is to preserve the developing corpus luteum and maintain pregnancy by producing progesterone and thus preventing menstrual shedding. In 8 of 17 cases of ectopic pregnancy, progesterone values were in the range of the proliferative phase of a normal cycle (0.1-1ng/ml), whereas the levels of hCG were 299-1600 mIU/ml. In 8 cases the progesterone levels were in the range of the secretory phase (2.3-6.9 ng/ml), and the hCG level was 182-5500 mIU/ml. In 1 case only was the progesterone level 15.0 ng/ml with an hCG level of 325 mIU/ml. In normal pregnancies of the same gestational age, the values of progesterone were 3.8-18.7 ng/ml, and the levels of hCG were 260-1300 mIU/ml. It seems that in addition to the level of hCG, a normal fetoplacental unit is needed for the preservation of the function of the corpus luteum.

Chorionic Gonadotropin↗
PubMed1977

Foam test, amniotic fluid cytology, creatinine and fetography in evaluation of fetal maturity.

Amniocenteses were performed in 73 pregnant women for maturity assessment in cases of high risk pregnancies, pregnancies of unknown gestational age and before an elective cesarean section. The evaluation of fetal maturity was based on: 1) foam test; 2)amniotic fluid cytology; 3)creatinine concentration; 4) fetography and 5) clinical criteria. The results which were assessed as to the proven infant maturity were as follows: Foam test 84.3%, lipid laden cells 75%; Creatinine 62.5% and fetography 56.3%.

Amniocentesis↗
PubMed1976

Metabolism and transport of galactose by rat intestine.

Intestinal uptake and metabolism of galactose were examined in everted jejunal rings from fasted adult rats using 0.2-28 mM sugar. After 60-min incubations, the total uptake (free tissue plus amount metabolized) of galactose ranged from 1.75 mumol/g at 0.2 mM to 21 mumol/g at 28 mM. Free tissue galactose was 17% of the former and 73% of the latter amount while that oxidized to 14CO2 represented only 6-16% of amount taken up. Compared to glucose, similar amounts of galactose are taken up at 0.2-2.0 mM, however, gllcose rtween 0.2 and 2 mM similar amounts of both sugars are metabolized, although a greater portion of the glucose is oxidized to 14CO2. Above 2.0 mM, 2-3 times more glucose is metabolized than galactose. Both uptake and metabolism showed saturability and kinetic analysis revealed two limbed Linweaver-Burk plots, suggesting operation of a high affinity low Km and a low affinity high Km system for sugar transport. In a series of in vivo studies, to assess the role of the intestine in the total body metabolism of galactose, 14C-labeled galactose injected intraperitoneally at a dose of either 50 or 300 mg into fasted normal, sham operated and enterectomized rats, no observable difference in 14CO2 production resulted in between the groups. It would thus appear that although extensive metabolism of galactose may take place in intestinal tissue in vitro, the intestine does not play a significant role in galactose disposition in vivo.

Animals↗
PubMed1976

[Multiple lipomas of the colon and rectum].

The authors report a case of multiple circumscribed colonic lipomas and undertake a review of the literature. Since the end of the 18th century, 45 clinical and autopsy cases have been reported. These exceptional lesions are sometimes strictly latent and discovered by chance, sometimes they may give rise to a picture of chronic intestinal obstruction and, more rarely, that of intussusception. Comparison of radiology and colonoscopy permits one to better suspect the diagnosis for there are unusual signs concerning both lesions. The treatment is mainly surgical but sometimes lipomectomy by the endoscopic route may be carried out when the lesions are not numerous.

Adult↗
PubMed1976

Effect of maleic acid on the kinetics of alpha-methyl-D-glucoside uptake by isolated rat renal tubules.

ALPHA-Methyl-D-glucoside has been used to study the invitro mechanism of the effect of maleic acid on sugar transport, using isolated rat renal tubule fragments. 6 mM maleate maximally inhibits the ability of the tubule to establish a concentration gradient for this model sugar with no evidence of ultrastructural changes. This inhibition is due to a 100% increase in efflux, as well as to a 50% decrease in influx with more prolonged incubation. The data presented here are consistent with those of other workers, but their work does not explain our results, which therefore deserve further investigation by other techniques.

Animals↗
PubMed1976

Regulatory characteristics of amino acid transport in newborn rat renal cortex cells.

The uptaken of alpha-aminoisobutyric acid by slices of kidney cortex from newborn rats is enhanced by a preliminary incubation of the tissue in buffer at 37 degrees C. This effect is abolished by anaerobiosis, the presence of dinitrophenol or the removal of Na+ during the preliminary incubation. Cycloheximide (50 muM) and purimycin (1 mM) as well as alpha-aminoisobutyric acid, glycine and proline (5 mM) in the preincubation buffer also abolish the effect, while actinomycin D (0.8 muM) partially the phenomenon indicates that the enhanced uptake is due to an increased entry rate into the cells without a change in effux. There is no alteration in the apparent transport Km but an increase in the V for entry. The effect is dependent on tissue age being observed between birth and 22 days, after which there is a decrease in response to preliminary incubation with no effect seen in adult tissues.

Aging↗
PubMed1976

Isolation and characterization of the brush border fraction from newborn rat renal proximal tubule cells.

A renal brush border fraction was isolated from newborn Sprague-Dawley rats, and its morphological and enzymatic characteristics were studied in comparison to that from the adult. Definite microvillar structures are seen by electron microscopy, and border preparations from the newborn are enriched in known marker enzymes. Though morphological development is more advanced and enzyme specific activities are greater in the adult, polyacrylamide gel electrophoresis of membrane proteins reveals no significant change in pattern with increasing age. These studies suggest that the brush border of the proximal tubule cell is present at birth as a significantly developed structure.

Adenosine Triphosphatases↗