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Biomedical subjects

E Okon

Publications and source records attributed to E Okon.

At least 163 records · Page 9Linked to original sources
PubMed1981

Effect of dioctyl sodium sulfosuccinate on cyclic AMP and prostaglandin E2 contents, and Na,K-ATPase, adenylate cyclase and phosphodiesterase activities in rat intestine.

The hypothesis that dioctyl sodium sulfosuccinate (DSS) induces intestinal fluid accumulation by inhibiting Na,K-ATPase activity and/or by increasing mucosal prostaglandin E2 (PGE2) content was tested in rats. Eighteen hours after its intragastric administration, DSS (260 mg/kg body weight) significantly decreased jejunal and colonic Na,K-ATPase activity--22.0 1.8 (SE) and 25.1 +/- 3.3 compared with 42.1 +/- 1.6 and 37.0 +/- 2.9 mumol . mg protein-1 . h-1, respectively, in saline-treated rats. DSS increased jejunal and colonic PGE2 content--155 +/- 15 (SE) and 273 +/- 40, compared with 109 +/- 9 and 175 +/- 23, pg/mg wet weight, respectively, in control rats. Although jejunal adenylate cyclase and phosphodiesterase activities were not affected by DSS (520 mg/kg body weight), they were significantly stimulated in the colon. Mucosal cyclic AMP content was similar in rats treated with DSS and saline. Patchy histological changes confined to surface absorptive cells were induced by DSS in both the jejunum and the colon. These findings suggest that inhibition of intestinal Na,K-ATPase activity and increase in mucosal PGE2 content might contribute to the net water accumulation induced in the rat intestine by DSS.

Adenylyl Cyclases↗
PubMed1980

Human prothymocytes. Membrane properties, differentiation patterns, glucocorticoid sensitivity, and ultrastructural features.

Thymic precursor cells (prothymocytes) comprise a large proportion of the fetal thymic cell population, but are less frequently encountered in the postnatal thymus, where they compose < 1% of the entire population. In the present study we attempted to characterize a number of properties of the prothymocytes obtained from human fetal thymic tissues after depletion of the E-rosette thymocyes on a Ficoll-Hypaque gradient. The prothymocytes are larger than the thymocytes and show a different nuclear chromatin pattern. This subset of cells lacks the E-rosetting and natural-attachment capacities and, unlike thymocytes, does not bind the lectin peanut agglutinin. Human prothymocytes are highly sensitive to the in vitro cytolytic effect of hydrocortisone, whereas the thymocytes are resistant. Long-term in vitro culture of prothymocytes resulted in the expression of thymocyte characteristics together with a burst of mitotic activity. Results of this study indicate that the rate of the prothymocyte proliferation is regulated by the small thymocytes present in the same suspension.

Antigens, Surface↗
PubMed1980

Effects of bisacodyl on cAMP and prostaglandin E2 contents, (Na + K) ATPase, adenyl cyclase, and phosphodiesterase activities of rat intestine.

The hypothesis that bisacodyl induces inotestinal fluid accumulation by increasing mucosal PGE2 content, inhibiting (Na + K) ATPase, and stimulating adenyl cyclase activities was tested in rats. Eighteen hours after its intragastric administration, bisacodyl (5.9 mg/kg body wt) decreased significantly jejunal and colonic (Na + K) ATPase activity: 36.4 +/- 1.4 (SE) and 28.3 +/- 1.4, respectively, as compared to 42.1 +/- 1.6 and 37.0 +/- 2.9 mumol/mg protein/hr in saline-treated rats. Bisacodyl administration increased significantly jejunal and colonic PGE2 content and stimulatd jejunal and colonic adenyl cyclase activity as compared to those in control rats. Jejunal and colonic cAMP content was not significantly increased by bisacodyl. Four hours after its administration, bisacodyl increased intestinal PGE2 content but failed to stimulate adenyl cyclase activity. Pretreatment with indomethacin prevented the increase in PGE2 content and the stimulation of adenyl cyclase induced by bisacodyl. Only jejunal phosphodiesterase activity was stimulated by bisacodyl (10 mg/kg body wt). The results reported thus suggest that intestinal inhibition of (Na + K) ATPase activity, increase of mucosal PGE2 content, and possibly also stimulation of adenyl cyclase activity might contribute to the net water accumulation induced by bisacodyl. It is also suggested that the stimulation of adenyl cyclase activity is mediated by increase in mucosal PGE2 content.

Adenosine Triphosphatases↗
PubMed1980

In vivo T-lymphocyte response against spontaneous reticulum cell neoplasms in SJL/J mice.

The properties of lymphocytes associated with reticulum cell neoplasms (RCN) (type B) occurring spontaneously in SJL/J mice were examined. The activity of 20 alpha-hydroxysteroid dehydrogenase (20 alpha-SDH) was used as a marker for activated T-cells. High levels of this enzyme were found in cell suspensions of tumors taken from 6- to 7-month-old mice. Treatment of the cells derived from tumorous organs with anti-theta serum and complement resulted in a loss of the 20 alpha-SDH activity; this indicated that T-lymphocytes populate the RCN. The activated T-cells in the neoplastic tissue were larger than small lymphocytes. In the more advanced stage of tumor growth seen in 1-year-old mice, the percentage of malignant reticulum cells was low and the neoplastic tissue showed low levels of 20 alpha-SDH activity. Tumor cells irradiated in vitro triggered syngeneic lymphocytes to proliferate in tumor-lymphocyte mixed cultures. The T-cell proliferative response measured by [3H]thymidine incorporation was accompanied by a marked increase in 20 alpha-SDH activity. The spleen cells taken from mice bearing old tumors that showed marked fibrosis did not respond to T- and B-cell mitogens. Histologically, the structure of the spleen was preserved, with few or no tumor cells. Spleen cells from age-matched healthy mice responded to mitogens.

20-Hydroxysteroid Dehydrogenases↗
PubMed1980

Male pseudohermaphroditism due to 5 alpha-reductase deficiency. Ultrastructure of the gonads.

We report here the results of the endocrine studies and the morphological findings of the gonads in two male pseudohermaphrodite siblings with 5 alpha-reductase deficiency. Basal levels of luteinizing hormone, follicle-stimulating hormone, and prolactin were elevated and rose to very high levels in response to gonadotropin-releasing hormone and thyrotropin-releasing hormone,, when compared to those in normal males, while thyroid-stimulating hormone response was normal. Serum testosterone levels were within the normal range, and estradiol values were modestly elevated. Diagnosis was confirmed by lack of conversion of 3H-testoterone to 3H-dihydrotestosterone by fibroblasts taken from perineal skin. Pathologic examination of the testes in both patients disclosed tubular atrophy and complete arrest of spermatogenesis, with numberous hyperplastic Leydig cells containing large Reinke crystalloids.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1980

Immunization against gonadotrophin-releasing hormone: histopathological and hormonal changes in the female rat.

Immunization of female rats against gonadotrophin-releasing hormone (GnRH) resulted in cessation of the oestrus cycles, undetectable serum gonadotrophin levels and a reduction of pituitary gonadotrophin stores and of hypothalamic content of GnRH. Immunization abolished the post-ovariectomy rise in serum levels and in pituitary content of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) without affecting prolactin levels. This suggests that GnRH is involved in the regulation of synthesis as well as the secretion of LH and FSH. Histopathological changes were found in the pituitary, ovaries and uterus of the immunized rats. A marked reduction in the number of gonadotrophs as well as a small decrease in the size of other cells was observed in the pituitaries of rats having high anti-GnRH titres. Rats immunized 5 weeks before castration showed a marked reduction in the number and in the size of castration cells. The ovaries exhibited various degrees of atrophy which were correlated with the anti-GnRH titres. Rats with high anti-GnRH titres revealed extensive atrophy of stromal cells with disappearance of large follicles and corpora lutea; ovaries of rats with low titres of antibodies exhibited small corpora lutea and larger follicles, some of which were cystic. Uteri of rats having high titres of anti-GnRH were severely atrophied with cystic glandular dilation. Uteri of rats with low anti-GnRH titres showed squamous-cell metaplasia and fibrosis of the endometrial stroma.

Animals↗
PubMed1979

Estradiol and testosterone levels in the peripheral and ovarian circulations in patients with endometrial cancer.

Estradiol and testosterone levels in the peripheral and ovarian circulation of patients with endometrial cancer and of postmenopausal women were studied. These levels proved to be the same in the two groups. The ovaries of neither group secreted estradiol. The testosterone level in the ovarian circulation of all examined women was four times higher than that in the peripheral circulation, thus indicating the ovarian origin of testosterone.

Aged↗
PubMed1977

Excretion of alpha-foetoprotein in the urine of rats during exposure to 3'-methyl-4-dimethylaminoazobenzene.

Female rats were maintained on standard laboratory diet, Miller's diet or Miller's diet containing 3'MeDAB. Animals fed standard or Miller's diet did not excrete alpha-foetoprotein (AFP) in their urine. Early appearance of AFP was demonstrated by examining the urine of rats on the 3'MeDAB regimen. The incidence of positive urine samples was high between the 5th and 7th week of the experiment. It thereafter declined, but from the 3rd month it steadily rose and reached a maximum of 80% at about 10 months. Though urinary excretion of AFP was irregular in individual animals, several positive urine samples were obtained from all rats followed for more than a few months. The urine of 90% of hepatoma-bearing rats contained AFP at the time of killing. The incidence of elevated serum AFP levels as determined by immunodiffusion, increased with the duration of the experiment, but was still only 70 percent in rats fed 3'MeDAB for over 34 weeks. The severity of the hepatic alterations, as well as hepatocytic uptake of [3H]thymidine, increased with time. The serum of animals fed the standard diet was negative, whereas AFP was very infrequently detected in the serum of rats given Miller's hypoprotein diet. The results demonstrate that, in a population exposed to hepatocarcinogenic agent, the recurring detection of urinary excretion of AFP is a useful indicator of the high risk of developing hepatomas.

Animals↗
PubMed1977

The role of prostaglandins in experimental arthritis in the rat.

In the experimental model of streptococcal CFE-induced arthritis, PGE and PGF concentrations rise significantly. This is due to an increase both in the substrate concentration and the enzyme activity for PG biosynthesis. Indomethacin therapy inhibited PG synthesis and diminished some of the gross, but not the histological, features of the inflammatory response. These results lend further support to the contention that the beneficial effect of indomethacin in arthritis is due to inhibition of PG biosynthesis.

Animals↗
PubMed1977

alpha-fetoprotein in rats treated with anti-thymocytic serum.

Serum alpha-fetoprotein was detected by immunodiffusion in rats treated with anti-thymocytic serum. Augmented synthesis of AFP is related to compensatory hyperplasia of liver cells secondary to a state of hypoproteinemia in the proteinuric nephritic animals. The nephritis was produced by the anti-basement membrane antibodies present in the thymocytic antiserum.

Animals↗
PubMed1976

Splenectomy, iron overload and liver cirrhosis in beta-thalassemia major.

In order to evaluate the interrelations of splenectomy, iron overload and cirrhosis, histologic specimens of liver and spleen were examined and correlated in 12 children with beta-thalassemia major. All patients had received blood transfusions since infancy. Correlations seemed to exist between splenic hemosiderosis and splenic weight, and between the latter and the age at time of splenectomy. All liver samples showed varying hemosiderosis, not correlated with the number of transfusions or the children's age. Irregular liver cirrhosis existed in three children, 7, 8, and 14 years after splenectomy. No cirrhosis existed in any of the children where the spleen was in situ. Splenectomy in children with thalassemia may carry the long-term risk of liver cirrhosis.

Adolescent↗