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Biomedical subjects

N Katz

Publications and source records attributed to N Katz.

At least 145 records · Page 8Linked to original sources
PubMed1990

Isopropyl alcohol intoxication.

Three patients had neurologic signs due to isopropyl alcohol (IPA) intoxication. Over a several-week period, a known alcoholic developed apathy, confusion, ataxia, and hyperreflexia. During this period, there was no ethanol available to him, and he denied use of other intoxicants. He was found stuporous in the hospital after drinking IPA and admitted to IPA abuse during the preceding weeks. Two other men were admitted in a stupor after large ingestions of IPA. Intoxication with IPA has two different presentations: stupor in a known alcoholic and encephalopathy of unknown cause in individuals who hide their addiction. Ethanol, methanol, IPA, and ethylene glycol intoxications are associated with different clinical and laboratory findings.

1-Propanol↗
PubMed1989

Zonal distribution of fatty acid synthase in liver parenchyma of male and female rats.

1. A sensitive radiochemical assay was established to determine the activity of fatty acid synthase in microdissected liver tissue of less than 1 microgram dry mass. 2. In female rats, the enzyme activity in perivenous tissue was twice that in periportal liver tissue while it was homogeneously distributed in livers of male animals. The overall activity was higher in female than in male animals. 3. The absolute activity, as well as the perivenous/periportal ratio, was reduced during starvation and in diabetes. They were greatly increased after refeeding to values above those observed in animals during normal feeding. 4. Ovariectomy or administration of testosterone to female rats resulted in a significant reduction of the zonal heterogeneity. 5. Castration or administration of estradiol to male animals was followed by an increase in the enzyme activity exclusively in the perivenous tissue, resulting in a zonal heterogeneity as observed in female rats.

Animals↗
PubMed1989

Functional specialization of different hepatocyte populations.

Hepatocytes from the periportal (afferent) and perivenous (efferent) zones of the liver parenchyma differ in their enzyme content and subcellular structures and thus have different metabolic capacities. Therefore the model of metabolic zonation proposes a functional specialization for the two zones: 1) oxidative energy metabolism with beta-oxidation, amino acid catabolism, ureagenesis, gluconeogenesis for the synthesis of both glucose and glycogen, cholesterol synthesis, bile formation, and protective metabolism are predominantly located in the periportal zone; 2) glycolysis, glycogen synthesis from glucose, liponeogenesis, ketogenesis, glutamine formation, and xenobiotic metabolism are preferentially situated in the perivenous zone. The input of humoral and nervous signals into the two zones is different. During passage of blood through the liver acinus, concentration gradients of oxygen, substrates, and hormones are established; the nerve densities in the two zones seem to be different. The different expression of the genome in upstream and downstream hepatocytes can be caused among other factors by the zonal gradients in oxygen and hormone concentrations. The functional specialization of the different hepatocyte populations is especially well documented for carbohydrate, amino acid, ammonia, and xenobiotic metabolism as well as for bile formation by a number of different approaches. Zonal flux differences were calculated from enzyme and metabolite distributions measured in vivo. They were observed in periportal- and perivenous-like hepatocytes in cell culture and in hepatocyte populations enriched in periportal and perivenous cells. They were detected also during ortho-and retrograde liver perfusion and finally by noninvasive techniques, using surface micro-light guides and miniature oxygen electrodes. The peculiar zonal hepatotoxicity of many xenobiotics can be explained at least in part by the enzymatic and fine-structural hepatocellular heterogeneity.

Animals↗
PubMed1989

[Schistosomiasis mansoni in the southwest of the State of Minas Gerais (Brazil)].

A new focus of schistosomiasis mansoni at Passos, a town in the Southwest of the State of Minas Gerais (Brazil), region until now considered free of the disease is reported. Malacological surveys showed Biophalaria glabrata naturally infected with Schistosoma mansoni in a country club near Passos. All B. straminea captured at the pisciculture station of the Furnas hydroelectric dam were negative. Six out of seven individuals living in the country club were found to be infected with S. mansoni, including four children who had never been out of Passos. The epidemiological importance of these findings is discussed.

Animals↗
PubMed1989

Knowledgeability of theories of occupational therapy practitioners in Israel.

A reflective occupational therapist is conceived as one who values theory and uses it as a tool for setting and solving problems in clinical situations. In this study, we investigated the extent of knowledge ability of theories of occupational therapy practitioners in Israel. Data were collected in two stages: (a) through personal interviews with a representative sample of all occupational therapists (n = 98) with the use of a semistructured questionnaire and (b) through telephone interviews of recent graduates of one school (n = 40) with the use of a shortened version of the original questionnaire. The findings from an open-ended question concerning knowledgeability theories reflected (a) the degree of the theories' scientific development, (b) the differentiation between models conceived as theories and those seen as techniques for treatment, and (c) the changes in professional curricula resulting from scientific and clinical developments in the field. In addition, a more general knowledge level, termed recognition, showed a consistent understanding of the theories and treatment modalities relevant in the practitioners' specialty areas. The results of this study indicate a need for further articulation of theory in clinical practice as well as better educational preparation of the "reflective practitioner" (Scbön, 1983).

Health Knowledge, Attitudes, Practice↗
PubMed1989

Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) battery for brain-injured patients: reliability and validity.

The purpose of this study was to determine the reliability and validity of the Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) battery. The battery provides an initial profile of the cognitive abilities of the brain-injured patient that can be used as a starting point for occupational therapy intervention and as a screening test for further assessment. The LOTCA consists of 20 subtests and is divided into four areas: orientation, visual and spatial perception, visuomotor organization, and thinking operations. The battery takes 30 to 45 minutes to administer. Subjects in the study consisted of two patient groups (20 traumatic head injury patients and 28 cerebrovascular accident patients) and one control group (55 non-brain-injured adults). Results showed interrater reliability coefficients of .82 to .97 for the various subtests and an alpha coefficient of .85 and above for the internal consistency of the areas of perception, visuomotor organization, and thinking operations. The Wilcoxon two-sample test showed that all subtests differentiated at the .0001 level of significance between the patient groups and the control group. This supported the LOTCA's validity. Furthermore, factor analysis provided initial construct validation for three areas of the battery: perception, visuomotor organization, and thinking operations.

Adult↗
PubMed1989

Curative and protective activity in rabbits after reinfection with Schistosoma mansoni: a new model of immunity?

New Zealand rabbits were infected on day 1 and challenged on days 15, 30, and 60 with 1,000 Schistosoma mansoni cercariae/animal/infection. Challenged and control rabbits were perfused 60 days after each infection, corresponding to days 75, 90, and 120 after the first exposure. No decrease in number of adult schistosomes occurred in animals reinfected 15 days after primary infection, but, when the rabbits were challenged 30 and 60 days after the first infection, worm burden reduction of 61.4% and 92.6%, respectively, was observed as compared to infection controls. These data indicate that rabbits submitted to reinfection are able to kill the worms from their primary infection, besides being protected against challenge parasites.

Animals↗
PubMed1988

Remodeling of a rat hepatocyte plasma membrane glycoprotein. De- and reglycosylation of dipeptidyl peptidase IV.

The present paper demonstrates the terminal de- and reglycosylation of a rat hepatocyte plasma membrane glycoprotein, dipeptidyl peptidase IV (DPP IV). Cultured hepatocytes were used in pulse-chase experiments with [3H]L-fucose and [14C]N-acetyl-D-mannosamine as markers for terminal carbohydrates, [3H]D-mannose as marker of a core-sugar, and [35S]L-methionine for labeling the protein backbone. Membrane DPP IV was immunoprecipitated with a polyclonal antibody which bound selectively at 4 degrees C to the cell-surface glycoprotein. The times of maximal labeling of hepatocyte plasma membrane DPP IV were 6-9 min for [3H]L-fucose, 20 min for [3H]D-mannose, and 25 min for [35S]L-methionine. When antibodies were bound to cell-surface DPP IV at 4 degrees C, the immune complex remained stable for more than 1 h after rewarming to 37 degrees C, despite ongoing metabolic and membrane transport processes. This was shown by pulse labeling with [35S]L-methionine at 37 degrees C, followed by cooling to 4 degrees C, and addition of antibody against plasma membrane DPP IV. During rewarming, the radioactivity in the complex remained constant. In a similar experiment with [3H]L-fucose, the radioactivity in the immune complex declined rapidly, indicating a defucosylation of the plasma membrane glycoprotein. Using the same experimental design with [3H]D-mannose, the radioactivity in the immune complex remained constant, showing that the core-sugar D-mannose is not cleaved from the membrane glycoprotein. Terminal reglycosylation (refucosylation and resialylation) was demonstrated as follows. Hepatocytes were maintained at 37 degrees C in a medium supplemented with tunicamycin in order to block the de novo synthesis of N-glycosidically bound carbohydrate chains. At 4 degrees C the antibody against DPP IV bound only to cell surface glycoprotein. During the rewarming period at 37 degrees C, radioactivity from [3H]L-fucose and [14C]N-acetyl-D-mannosamine became incorporated into the immune complex. This indicates a fucosylation and sialylation of the glycoprotein originally present at the cell surface. The mechanisms whereby terminal de- and reglycosylation of plasma membrane glycoproteins may occur during membrane recycling are discussed.

Animals↗
PubMed1988

Anthropometric measures in relation to Schistosomiasis mansoni and socioeconomic variables.

A cross-sectional study of anthropometric measures and their association with socioeconomic variables, infection by Schistosoma mansoni, intensity of infection and splenomegaly was carried out in an endemic area for schistosomiasis in Brazil (Comercinho), using multiple logistic regression methods. Eighty-seven per cent of all 1.5-14.4 year-old children in the area participated in the study. Children below the 5th percentile (USA Ten State Survey) for height-for-age, weight-for-age and arm muscle area-for-age were compared to those greater than the 5th percentile. There was no association between low anthropometric measures and schistosomiasis or socioeconomic variables in children under five years of age. For the 4.4-14.4 year-old children, poor condition of the heads of family and poorer housing were independently associated with low height and arm muscle area. Heavy excretion of S. mansoni eggs (greater than or equal to 500 epg) was related to low height, and splenomegaly was the variable which showed the strongest association with low height, weight and arm muscle area (odds ratios adjusted for socioeconomic variables were 6.4, 3.5 and 3.7 respectively). This indicates that there is a biological component for low anthropometric measures in the severe form of schistosomiasis and this reinforces the need for public health measures to prevent the development of splenomegalies in endemic areas.

Body Height↗
PubMed1987

Decrease in glucokinase and glucose-6-phosphatase and increase in hexokinase in putative preneoplastic lesions of rat liver.

Preneoplastic liver lesions were produced in female Wistar rats by oral administration of 2-acetylaminofluorene for 165 days succeeded by a carcinogen-free standard diet up to 420 days. During the treatment numerous altered hepatic foci (AHF) and hyperplastic nodules (HN) were detected histochemically by a focal decrease or lack of adenosine-5-triphosphatase and glucose-6-phosphatase (G-6-Pase) activities. In addition, the immunohistochemically demonstrable amount of L-type pyruvate kinase was clearly reduced. The histochemically demonstrated decrease of G-6-Pase was substantiated by microbiochemical determination of the enzyme activity in microdissected material. Moreover, during the experimental period a continuous decrease in glucokinase and an increase in hexokinase was detected microbiochemically within AHF and HN. These alterations indicate a shift in the carbohydrate metabolism from gluconeogenesis to glucose utilization and pentose-phosphate-pathway for biosynthesis of nucleic acids. Beside other oncofetal markers, HK may be used as indicator of the early stages of liver carcinogenesis.

2-Acetylaminofluorene↗
PubMed1987

Immunohistochemical demonstration of decreased L-pyruvate kinase in enzyme altered rat liver lesions produced by different carcinogens.

Preneoplastic liver lesions were produced in female Wistar rats by application of 25 mg/kg N-nitrosomorpholine (NNM), 14 mg/kg diethylnitrosamine (DENA), 0.075 mg/kg aflatoxin B1 (AFB1) or 160 mg/kg safrole. These carcinogens were administered in two equal doses 12 and 24 h after partial hepatectomy. The animals then received sodium phenobarbital (0.1% in tap water) for up to 410 days. Numerous altered hepatic foci (AHF) and hyperplastic nodules (HN) were detected enzyme histochemically by their negative ATPase reaction after application of AFB1, DENA and NNM; some AHF and HN were also caused by the weak carcinogen safrole. Immunohistochemically these lesions were also L-pyruvate kinase (L-PK)-negative with a high coincidence with regard to their number and area. These results confirm the role of L-PK, an enzyme affecting the pentose phosphate pathway, as a negative marker of preneoplastic liver lesions.

Animals↗