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Biomedical subjects

N Katz

Publications and source records attributed to N Katz.

At least 163 records · Page 9Linked to original sources
PubMed1987

Tolerance of Kenyan Schistosoma mansoni to oxamniquine.

Although 30 mg/kg oxamniquine produced high levels (85.5 to 99.5%) of egg reduction in Kenyan children infected with Schistosoma mansoni after a single oral treatment, cure rates from children at Mwea in Kirinyaga district were lower than those from Machakos (58% v. 74%). Redosing uncured children confirmed this lower cure rate (36% v. 83%). Isolates from infected children were passaged into mice and dosed with oxamniquine. Lower than expected reductions in worm numbers were obtained, suggesting that oxaminiquine tolerant S. mansoni are present in the normal worm population in Kenya. It is concluded that mass use of oxamniquine at 30 mg/kg may produce problems of drug resistance.

Administration, Oral↗
PubMed1987

Retinoblastoma. Immunohistochemistry and cell differentiation.

Tumor from eight enucleated eyes was analyzed by immunohistochemistry, using a panel of specific antibodies including interphotoreceptor retinoid-binding protein (IRBP), S-antigen (S-Ag), opsin, neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), laminin, and vimentin. In addition, immunoelectron microscopy and enzyme-linked immunosorbent assay (ELISA) for IRBP were performed. Immunohistochemical staining disclosed the most pronounced labeling of tumor cells with NSE and IRBP antibodies. A correlation was found between the degree of tumor differentiation and amount of IRBP, a protein specifically synthesized by photoreceptor cells. Moderate labeling of the better differentiated tumors was also observed with antibodies against S-Ag and focal labeling in a few tumors with opsin antibodies. Anti-GFAP labeling was limited to a smaller number of reactive glial cells and perivascular glial cells. These data indicate the essential neuronal nature of retinoblastoma tumor cells in situ as well as at least partial photoreceptor-like features, as shown by the presence of recognized photoreceptor cell markers (IRBP, S-Ag, opsin). Tissue culture studies using the human Y-79 retinoblastoma cell line also demonstrate that the tumor cells are primitive multipotential retinoblasts capable of at least partial differentiation along neuronal, glial, or pigment epithelial cell lines.

Antibodies, Anti-Idiotypic↗
PubMed1987

Granulomatous hypersensitivity to Schistosoma mansoni egg antigens in human schistosomiasis. I. Granuloma formation and modulation around polyacrylamide antigen-conjugated beads.

We have developed an in vitro model of granuloma formation for the purpose of studying the immunological components of delayed type hypersensitivity granuloma formation in patients infected with Schistosoma mansoni. Our data show that 1) granulomatous hypersensitivity can be studied by examining the cellular reactivity manifested as multiple cell layers surrounding the antigen conjugated beads; 2) this reactivity is a CD4 cell dependent, macrophage dependent, B cell independent response and 3) the in vitro granuloma response is antigenically specific for parasite egg antigens. Studies designed to investigate the immune regulation of granulomatous hypersensitivity using purified populations of either CD4 or CD8 T cells have demonstrated the complexity of cellular interactions in the suppression of granulomatous hypersensitivity. The anti-S. mansoni egg immune responses of individual patients with chronic intestinal schistosomiasis can be classified either as soluble egg antigen (SEA) hypersensitive with maximal granulomatous hypersensitivity or SEA suppressive with activation of the T cell suppressor pathway with effective SEA granuloma modulation. Our data suggest that T cell network interactions are active in the generation of effective granuloma modulation in chronic intestinal schistosomiasis patients.

Animals↗
PubMed1987

Water-contact patterns and socioeconomic variables in the epidemiology of schistosomiasis mansoni in an endemic area in Brazil.

A study was carried out in Comercinho in south-east Brazil where information relating to socioeconomic factors and water contacts was obtained from 290 (99% of the total) households and 1208 (82% of the total) inhabitants, respectively. Stool examinations and physical examinations were performed on 90% and 82% of the population, respectively. The rates of Schistosoma mansoni infection and splenomegaly were higher in families whose heads were manual workers, in individuals living in houses without piped water and of poor construction, and in those who were born in Comercinho. A total of 1017 (84%) individuals reported water contact; 75% of these contacts were for household activities or bathing and 21% for leisure. The faecal egg counts decreased in persons over 15 years of age, while the degree (intensity) of water contact did not. The mean degree of water contact was higher in individuals without than with piped water in the household (96.8+/-0.6 v. 25.7+/-0.6). The main risk factors for splenomegaly weer no piped water, intense water contact, bathing in streams, and daily contact (odds ratio=7.3, 5.1, 4.5 and 3.6, respectively). These results indicate that the extension of piped water to houses should decrease the incidence of splenomegaly in this endemic area.

Adolescent↗
PubMed1987

[Chemoprophylactic activity of soaps containing essential oil from the fruit of Pterodon pubescens in schistosomiasis mansoni].

It has been studied the chemoprophylactic action on experimental schistosomiasis of the essential oil from Pterodon pubescens "sucupira branca" as an additive through different formulations, in toilet soap. Immediately or 24 hours later, groups of mice were exposed by tail method to Schistosoma mansoni cercariae. After 45 days of the exposition, the protective action of these soaps were evaluated. The results showed different levels of protection, ranging from 29.0 to 100.0%. Further studies are on going with the most promising formulations.

Animals↗
PubMed1986

Immune responses during human schistosomiasis mansoni. XIII. Immunological status of spleen cells from hospital patients with hepatosplenic disease.

Splenocytes from 25 patients with severe hepatosplenic schistosomiasis mansoni were obtained after therapeutic splenectomy. Spleen cells were phenotyped and analysed for responsiveness to mitogens or heterogeneous schistosome-derived antigenic preparations (eggs, SEA; adult worms, SWAP; cercariae, CERC) in blastogenesis assays and lymphokine production systems, and were compared with peripheral blood mononuclear cells (PBMN). Splenic lymphocytes were 55% T lymphocytes (sheep erythrocyte rosette-positive) and 37% surface immunoglobulin-positive B lymphocytes. The mean T4+:T8+ ratio of these splenocytes was 1.0. Phytohaemagglutinin stimulated spleen cell production of the lymphokine mitogenic factor, but exposure to SEA or SWAP did not. Spleen cell and PBMN blastogenic responses to SEA and SWAP were sometimes, but not always in accord. Removal of plastic adherent cells allowed the non-adherent spleen cells of 30-40% of the patients to respond substantially more vigorously to SEA, SWAP and CERC. Spleen cells from a subgroup of 20-30% of the patients failed to respond to the schistosomal antigens regardless of removal of adherent cells. Spleen cell responses to gram-negative lipopolysaccharide peaked on day 5 or 6 of culture, and were augmented by adherent cell removal. Pokeweek mitogen-stimulated responses were optimal on day 5 of culture. Spleen cells from most severe, hepatosplenic schistosomiasis mansoni patients do not respond well to schistosomal antigens or B-cell mitogens. The splenic responses of many of these patients were elevated by the removal of adherent spleen cells.

Adolescent↗
PubMed1986

Immune responses during human schistosomiasis. XII. Differential responsiveness in patients with hepatosplenic disease.

Thirty-four hospitalized patients and 12 ambulatory patients, all with hepatosplenic schistosomiasis mansoni were evaluated in regard to their peripheral blood mononuclear (PBMN) cell responses to schistosomal antigenic preparations and compared with groups of 40 patients with the hepatointestinal form and 39 patients with the more common, chronic intestinal form of schistosomiasis mansoni. PBMN cell blastogenic responses were measured upon exposure to schistosomal egg antigens (SEA), adult worm antigens (SWAP) and a cercarial antigenic preparation (CERC). All groups had some individuals who did not respond to some or all of these preparations. In the hospitalized hepatosplenic group greater than 50% did not respond to SEA. Analysis of the responses in each group revealed that all responders could be subdivided into moderate and high responders. High responders to SEA had experimental minus control values of greater than 8,000 counts per minute (CPM). For SWAP and CERC, this arbitrary cut-off value was greater than 25,000 CPM and greater than 11,000 CPM, respectively. The percent of high SEA responders in the groups differed considerably. This was 23% in the chronic intestinal group, 40% in the chronic hepatointestinal group, 67% for ambulatory hepatosplenic patients and 20% for hospitalized hepatosplenic patients. Previous studies had demonstrated that 94% of patients with early (2-3 month) acute schistosomiasis mansoni were high responders to SEA and none were nonresponders. Furthermore, at the other end of the spectrum, 100% of former schistosomiasis mansoni patients (treated and cured 7-35 years previously) were high responders to SEA. None were nonresponders to any of the antigen preparations. It is proposed that during acute infection all patients express vigorous responses to SEA. Upon continued infection most patients (75%) modulate this florid response. However, continued high responders comprise 40% of the chronic hepatointestinal cases and almost 70% of the ambulatory hepatosplenic patients. These latter 2 groups may likely represent early forms of the severe clinical disease found in the hospitalized hepatosplenic patient population. Fifty percent of the hospitalized group appear anergic and no longer respond to SEA, while only 20% are high responders. Long after chemotherapy it appears that the anti-SEA regulatory mechanisms of former chronic patients have subsided, leaving strong anti-SEA responsiveness.

Acute Disease↗
PubMed1985

A clinico-epidemiological survey of schistosomiasis mansoni in a hyperendemic area in Minas Gerais State (Comercinho, Brazil). I. Differences in the manifestations of schistosomiasis in the town centre and in the environs.

A cross-sectional survey of schistosomiasis was done in Comercinho (Minas Gerais State, Brazil). Faecal (Kato-Katz technique) and physical examinations were performed on 90% and 79% of the population (1474 inhabitants), respectively. The rate of infection with Schistosoma mansoni was 70%, the geometric mean of eggs was 334/g of faeces and 7% of the infected individuals had splenomegaly. The rate of infection, faecal egg counts and the rate of splenomegaly were significantly higher in the environs (zones 3 and 4) of the town than in the central areas (zones 1 and 2) of Comercinho. This difference seemed to be determined by the social differences existing between the population in the central area and the environs; in the environs the heads of families were predominantly manual workers (73 and 94% respectively), only 10 and 3% of the houses had piped water supply and less than 14% were of better quality.

Adolescent↗