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Biomedical subjects

N Epstein

Publications and source records attributed to N Epstein.

At least 55 records · Page 3Linked to original sources
PubMed1983

The influence of polycyclic hydrocarbons on the activity of NAD(P)H-dehydrogenating enzymes in rat thymus. A biochemical and histochemical study.

The action of benzo(a)pyrene, 3-methylcholanthrene and 7,12-dimethylbenzo(a)anthracene in the activity of the rat thymus D-T diaphorase (EC 1.6.99.2) and the NAD(P)H cytochrome C (EC 1.6.99.3) reductases of particulate fractions were studied in intact and adrenalectomized animals. These polycyclic hydrocarbons increased severalfold the activity of the D-T diaphorase in intact and adrenalectomized animals. The activities of the particulate enzymes were not affected by the carcinogens. Dicumarol suppresses the inducing effects of benzo(a)pyrene and adrenalectomy does not influence the inducing effects of benzo(a)pyrene and 3-methylcholanthrene. The histological distribution of the enzyme NAD(P)H-nitroblue tetrazolium reductase was studied and a marked increase in its activity in lymphocytes, macrophages and epithelial cells was found after the administration of the carcinogens.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1982

Rat splenic D-T diaphorase and NAD(P)H-nitroblue tetrazolium reductase. Their use to assess the action of polycyclic hydrocarbons in the lymphatic system.

The biochemical response of rat splenic D-T diaphorase and the histochemical distribution of the enzyme NAD(P)H-NBT reductase to the action of the polycyclic hydrocarbons benz(a)pyrene, 3-methylcholanthrene, 7,12-dimethylbenz(a)anthracene and benz(a)anthracene have been studied. The four polycyclic hydrocarbons tested in this work induced the activity of both enzymes. The stimulation of the D-T diaphorase by benz(a)pyrene is dose dependent and it is partially inhibited by dicumarol. Microsomal and mitochondrial NAD(P)H dehydrogenases are not induced by any of these compounds. The study of the histochemical distribution of the NAD(P)H-NBT reductase shows also a marked increase in the staining of the enzyme which follow a specific pattern, the cells showing the highest activity are the lymphocytes located around the marginal sinus of the white pulp and around follicular arterioles, plus red pulp lymphocytes and myeloblastic cells. The cells in the germinal center show from null to very weak activity. A correlation between the biochemical induction of the soluble D-T diaphorase of the histochemical increase of the NAD(P)H-NBT reductase is attempted.

Animals↗
PubMed1982

Intractable facial pain associated with a ganglioglioma of the cervicomedullary junction: report of a case.

A 6-year-old child with a brain stem tumor presented with the unusual complaint of intractable facial pain resembling trigeminal neuralgia in the absence of other symptoms or signs referable to the 5th cranial nerve. The radiological evaluation included a computed tomographic scan with intravenous contrast administration, which demonstrated an enhancing intramedullary lesion extending from the obex to C-4. After radiation and chemotherapy had failed to achieve symptomatic relief, the tumor, later proven to be a ganglioglioma, was radically removed with the ultrasonic aspirator. Postoperatively the patient experienced full pain relief.

Brain Neoplasms↗
PubMed1982

Acromegaly and spinal stenosis. Case report.

Spinal stenosis is a well defined clinical entity that is occasionally encountered in patients with acromegaly. Persistent elevation of growth hormone promotes hypertrophy of the bones and ligaments, resulting in widening of the thoracolumbar vertebral bodies, and developmental narrowing of the spinal canal. This report describes the case of a 54-year-old acromegalic man with a 30-year history of low-back pain. Who developed symptoms of spinal stenosis. This case and two similar cases from the literature are discussed, and the appropriate therapeutic approaches reviewed.

Acromegaly↗
PubMed1982

A residence for autistic and schizophrenic adolescents.

A community-based residence for male adolescents who require intensive training in basic life skills is described. Group therapy was used to promote eventual semi-independent living. Mastery over idiosyncratic behavior and learning how to obtain and hold a job constituted the main achievements of intervention.

Activities of Daily Living↗
PubMed1981

Freeze-fracture study on the erythrocyte membrane during malarial parasite invasion.

Invasion of erythrocytes by malarial merozoites requires the formation of a junction between the merozoite and the erythrocyte. Migration of the junction parallel to the long axis of the merozoite occurs during the entry of the merozoite into an invagination of the erythrocyte. Freeze-fracture shows a narrow circumferential band of rhomboidally arrayed particles on the P face of the erythrocyte membrane at the neck of the erythrocyte invagination and matching rhomboidally arrayed pits on the E face. The band corresponds to the junction between the erythrocyte and merozoite membranes observed in thin sections and may represent the anchorage sites of the contractile proteins within the erythrocyte. Intramembrane particles (IMP) on the P face of the erythrocyte membrane disappear beyond this junction. When the erythrocytes and cytochalasin B-treated merozoites are incubated together, the merozoite attaches to the erythrocyte membrane and a junction is formed between the two, but the invasion process does not advance further and no movement of the junction occurs. Although there is no entry of the parasite, the erythrocyte membrane still invaginates. Freeze-fracture shows that the P face of the invaginated erythrocyte membrane is almost devoid of the IMP that are found elsewhere on the membrane, suggesting that the attachment process in and of itself is sufficient to create a relatively IMP-free bilayer.

Animals↗
PubMed1981

Identification of surface proteins on viable Plasmodium knowlesi merozoites.

Viable merozoites of Plasmodium knowlesi were isolated and the proteins that were labeled on intact merozoites by lactoperoxidase-catalyzed radioiodination were identified. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography of Triton soluble extracts of labeled merozoites demonstrated eight major bands ranging in apparent molecular weight from 150,000 D to 22,000 D. Exposure of intact merozoites to trypsin (10 microgram/ml) for 10 min resulted in the loss of the two highest molecular weight proteins (150,000 D and 105,000 D) and the appearance of two new bands at 70,000 D and 62,000 D. Trypsin treatment under these conditions also removed the receptor(s) for merozoite attachment to erythrocytes. Therefore, these high molecular weight proteins are candidates for the merozoite component that attaches to erythrocytes. There was no evidence that the labeled membrane components were serum or erythrocyte membrane components, two potential contaminants in the preparation. Anti-rhesus erythrocyte antibody did not precipitate labeled merozoite proteins. Furthermore, the immunoprecipitation of labeled merozoite proteins by rhesus anti-merozoite serum was not inhibited by erythrocyte ghosts.

Animals↗
PubMed1981

Gastrointestinal bleeding in patients with spinal cord trauma. Effects of steroids, cimetidine, and mini-dose heparin.

The frequency and degree of gastrointestinal (GI) bleeding were examined in 131 patients with spinal cord injuries. All patients were randomly assigned to either high- or low-dose steroid regimens and some form of GI prophylaxis. The latter consisted of antacids alone or antacids supplemented with cimetidine when this medication became available. Segments of the population were treated with mini-dose or full-dose heparin. The incidence and degree of GI bleeding did not appear to be affected by steroid dose level, regimen of prophylaxis, or mini-dose heparin. Only full heparinization was found to significantly increase bleeding. These results place in question the benefits of adding cimetidine to antacids as a prophylactic atreatment in patients with no history of ulcer.

Adrenal Cortex Hormones↗
PubMed1981

Monoclonal antibodies against a specific surface determinant on malarial (Plasmodium knowlesi) merozoites block erythrocyte invasion.

Twelve hybridoma cell lines secreting monoclonal antibodies against Plasmodium knowlesi merozoites have been produced. Antibodies from 3 of the 12 lines agglutinated merozoites. The 2 monoclonal antibodies (13C11 and 16F8) that markedly agglutinated merozoites blocked merozoite invasion of erythrocytes. Of these 2 lines, the one that induced the most agglutination also blocked invasion most effectively. The third monoclonal antibody (53B3) caused minimal agglutination of merozoites and did not block invasion, nor did the other 9 nonagglutinating antibodies. The 2 blocking monoclonal antibodies bound to antigens around the entire surface of merozoites, as demonstrated by immunoelectron microscopy, and precipitated a single biosynthetically labeled protein of apparent m.w. of 250,000. None of the nonagglutinating lines precipitated this protein. Monoclonal antibodies 13C11 and 16F8 reacted with a common antigenic determinant on a Malaysian and a Philippine strain of P. knowlesi in that they blocked invasion and precipitated a 250,000 m.w. protein from both. Sera from immune monkeys also precipitated this 250,000 m.w. protein.

Agglutination↗
PubMed1980

Inactivation (desensitization) of the acetylcholine receptor in Electrophorus electricus membrane vesicles by carbamylcholine: comparison between ion flux and alpha-bungarotoxin binding.

The inactivation (desensitization) of the acetylcholine receptor by carbamylcholine, a stable analogue of acetylcholine, has been investigated in eel Ringer's solution, pH 7.0, 0 degrees C, by measurements of (i) ion flux and (ii) the kinetics of the reaction of [125I]-alpha-bungarotoxin with the receptor. The effect of preincubation with carbamylcholine is significantly different in the two types of measurement. In both the receptor-controlled flux of inorganic ions and the toxin-binding kinetics a biphasic process has been observed (Hess, G.P., Lipkowitz, S., Struve, G.E., 1978, Proc. Nat. Acad. Sci. USA 75:1703; Hess, G.P. et al., 1975, Biochem. Biophys. Res. Commun. 64:1018; Bulger, J.E. et al., 1977, Biochemistry 16:684), only the initial fast phase of which is inhibited and the subsequent slow phase persists. However, preincubation with carbamylcholine per se has no effect on the toxin reaction. The results obtained are consistent with the proposal of Katz and Thesleff (Katz, B., Thesleff, S., 1957, J. Physiol. (London) 138:65) that the active form of the receptor is converted to an inactive form in the presence of acetylcholine receptor ligands, and with our previous experiments (Hess et al., 1978) which indicated that one receptor form is responsible for the initial fast phase of both the receptor-controlled ion flux and the toxin binding reaction, and that its conversion to the other form results in the slow phases in these two measurements.

Animals↗