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Biomedical subjects

N Katz

Publications and source records attributed to N Katz.

At least 199 records · Page 11Linked to original sources
PubMed1983

Immune responses during human Schistosomiasis mansoni. VIII. Differential in vitro cellular responsiveness to adult worm and schistosomular tegumental preparations.

The proliferative responses of peripheral blood mononuclear cells from patients with Schistosoma mansoni infections were studied in response to heterogeneous schistosomal antigenic preparations derived from whole adult worms, cercariae or schistosomula, and soluble tegumental preparations from adult worms or schistosomula. The use of these preparations was standardized with a Brazilian patient population, and comparisons were made between previously used and newly, variously prepared antigenic preparations. Responses of cells from these intestinal/ambulatory patients were generally strong to whole adult worm antigens and low to moderate to whole cercarial or schistosomular materials. Although most patients responded well to whole worm extracts, they were not stimulated by the soluble adult tegumental preparation. In contrast, the responses to the soluble schistosomular tegumental material were vigorous. These responses were usually much higher than to whole schistosomula-derived materials. Thus it appears, using these particular preparations, that human schistosomal patient lymphocytes recognize and are stimulated by schistosomular tegumental antigens but they do not demonstrate good reactivity when exposed to an adult worm tegumental preparation.

Antigens↗
PubMed1982

The glucose/glucose-6-phosphate cycle in the periportal and perivenous zone of rat liver.

Periportal and perivenous hepatocytes contain different activities (V) of antagonistic key enzymes such as glucokinase and glucose-6-phosphatase. In order to get an insight into the metabolism of the periportal and perivenous area the flux rates (v) of the glucose/glucose-6-phosphate cycle were calculated on the basis of the Michaelis-Menten equation using the measured zonal concentrations of glucose and glucose 6-phosphate, the zonal activities of glucokinase and glucose-6-phosphatase previously reported and the half-saturating substrate concentrations (Km) of the two enzymes found in the literature. The concentrations of glucose were obtained as a first approximation by measuring the concentrations in portal (= periportal) and hepatovenous (= perivenous) blood; those of glucose 6-phosphate were calculated from the levels determined in microdissected periportal and perivenous liver tissue. The calculations showed (a) that the overall cycling rates agreed remarkably well with those reported for intact animals and (b) that during a normal feeding rhythm the periportal zone should catalyze net glucose output and the perivenous zone should mediate net glucose uptake, as proposed by the model of 'metabolic zonation'.

Animals↗
PubMed1982

Transmission and scanning electron microscopical studies in the tegument of male Schistosoma mansoni after oxamniquine treatment.

Schistosoma mansoni recovered from experimentally infected mice orally treated with oxamniquine were studied by transmission and scanning electron microscopy. The worms were examined 24 hours, 3, 7 and 10 days after a single dose of 100 mg/Kg of the drug. After oxamniquine treatment significant structural alterations were observed in tegumental, muscular and parenchymal levels. The initial alterations were confined to basal vacuolation in the tegument and to structural disorganization both in tegumental and non tegumental cells. Ten days after treatment, intercellular oedema became more prominent originating "bubble-like" lesions with varied dimensions. The intercellular oedema leading to the "bubble" formation seems to be the most striking feature caused by oxamniquine treatment.

Animals↗
PubMed1982

Comparative study of Schistosoma mansoni strains isolated from patients with toxemic or intestinal forms of schistosomiasis.

Six Schistosoma mansoni strains from Belo Horizonte (three from patients with the toxemic form of schistosomiasis and three from patients with the chronic intestinal form) have been experimentally compared. The following characteristics of infection were analyzed in the laboratory in mice: length of prepatent period, infectivity, total and differential white blood cell count, recovery of eggs in tissues, distribution of eggs in the viscera, and response to specific treatment. While significant differences existed among these six strains, those from patients with the toxemic form did not present a characteristic behavior that could clearly differentiate them from strains from non-toxemic patients. These results strongly suggest that the development of the toxemic form in man is not due to specific characteristics of the S. mansoni strain.

Adolescent↗
PubMed1980

Susceptibility to chemotherapeutic agents of strains of Schistosoma mansoni isolated from treated and untreated patients.

Seven strains of Schistosoma mansoni were isolated from the feces of patients. Three of the patients had been unsuccessfully treated with hycanthone or oxamniquine; the remaining four had not been given any specific treatment. Mice infected with these strains were treated 45 days later with niridazole (50 or 100 mg/kg body weight per day for 5 days, per os), hycanthone (single dose of 80 or 160 mg/kg, intramuscularly), or oxamniquine (single dose of 50 or 100 mg/kg, per os). Significant differences in the strains' responses to the schistosomicidal agents used were observed. Oogram changes in mice treated with the same drug ranged from 10--100%, and percentages of dead worms from 0--45. Such differences seemed to be dependent on the strain's specific characters rather than t their having been exposed to schistosomicidal drugs.

Adolescent↗
PubMed1979

The development of functional heterogeneity in the liver parenchyma of the golden hamster.

Prenatal and postnatal stages of the development of golden hamsters were studied histochemically and biochemically. It was shown that, beginning with the 12th gestational day, the fetal liver starts to store glycogen, and that this process reaches its maximum a birth. Glycogen phosphorylase and glucose-6-phosphatase (G6Pase)-activity increased drastically in the last two days before birth, glycogen phosphorylase preceding G6Pase. As a histochemical characteristic, an even distribution of glycogen, glycogen phosphorylase and G6Pase activity is found in the liver parenchyma at birth. During the first two postnatal weeks typical heterogeneous patterns of distribution developed: glycogen depletion could be demonstrated predominantly in zone 1 of the liver acinus, this being at the same time the area of highest glycogen phosphorylase and G6Pase-activity. The periportal zone 1 thus became characterized as the primary site of glycogenolysis (glycogen phosphorylase) and gluco(neo)genesis (G6Pase). "Metabolic Zonation" is interpreted as the chemomorphological equivalent of the regulatory function of the liver as a glucostat.

Animals↗
PubMed1979

Preliminary trials with praziquantel in human infections due to Schistosoma mansoni.

As part of a programme of multicentre trials of the tolerance and therapeutic effect of praziquantel, clinical trials were carried out in Brazil in patients with active Schistosoma mansoni infections, each of whom had a minimum geometric mean egg output of 100 eggs per gram of faeces calculated from multiple pretreatment stool examinations.The first stage was a double-blind assessment of tolerance and efficacy of oral doses of 1 x 20, 2 x 20, or 3 x 20 mg of praziquantel per kg of body weight. Subsequently, single-blind trials explored the effects of 3 x 20 mg/kg at 4-hourly intervals, and a single dose of 50 mg/kg.Side effects increased in frequency as dosage increased. Nausea, epigastric pain, headache, dizziness, and drowsiness were all noted but their severity was mild or moderate and they disappeared in 48 hours. In general, monitoring laboratory tests showed little change.Following a stringent parasitological follow-up, 96% of 28 patients followed at 1 year after treatment with either 3 x 20 mg/kg or 1 x 50 mg/kg were cured. Praziquantel seems to be a very promising drug against S. mansoni and further clinical trials should be strongly encouraged.

Adult↗
PubMed1978

Protein requirements in maintenance hemodialysis.

Protein requirements in maintenance hemodialysis patients are still unclear. Based on nitrogen balance studies and different analyses of protein and amino acid metabolism, the recommendations until recently were 1 g/kg of body weight, primarily of high biological value protein. According to the results of controlled long-term studies the 1 g recommendation now seems too low. The paper reports on the results of a controlled study undertaken to define protein requirements. The effect of supplementation with a special protein mixture is studied on the basis of 1 g of protein per kilogram of body weight intake and about 20 hr standard dialysis per week. The results suggest that 1.2 g of protein per kilogram of body weight primarily of high biological value protein and 35 kcal/kg of body weight should be prescribed for dialysis patients. In case of complications (bleeding, infection, and other stress situations) additional supplements are necessary.

Adult↗
PubMed1978

Amino acid content of erythrocytes in uremia.

The amino acid content of plasma and erythrocytes in patients with severe renal failure (serum creatinine less than 8 mg/100 ml) treated with selective low-protein diets, in patients on regular hemodialysis, and in a control group of healthy subjects were studied. Most amino acids in erythrocytes of the patients showed the same changes as in plasma with the exception of histidine, serine, and alanine. In spite of low histidine plasma levels, the erythrocytes level is increased as compared with healthy controls. In uremic patients the plasma serine was constantly reduced whereas the serine content of the erythrocytes did not differ from healthy controls. Alanine concentrations in the erythrocytes of uremic patients were increased in spite of normal alanine plasma levels. This finding may be due to the increased glycolytic ratio of red cells from uremic subjects delivering more pyruvate for transmination to alanine. In the control group the cysteine content of erythrocytes was decreased with a gradient between plasma and erythrocytes of 3.5:1. The same gradient could be observed in uremic patients in spite of the elevation in their plasma cysteine levels by a factor of 2.7 compared with controls. The low cysteine levels in erythrocytes may be due to loss of cysteine for glutathione synthesis in red cells. High glutathione levels in the erythrocytes of uremic patients support this hypothesis.

Alanine↗
PubMed1978

An evaluation of levamisole for treatment of ascariasis.

Levamisole (Decaris, Belgium) was tested in Iran, Brazil, and in Mississippi and Louisiana for its efficacy as a single-dose oral treatment for Ascaris infections. Subjects were children ages 2 to 15 years, and numbers treated with levamisole and comparative anthelmintics are as follows: 453 with levamisole; 461 with piperazine citrate; 17 with pyrantel pamoate; and 19 with a placebo. Cure rates and total reduction in mean egg counts observed were 92% and 98% respectively for levamisole and 66% and 90% for piperazine. Sixteen of 17 treated with pyrantel pamoate were cured. In none of the drugs were there notable side reactions, but in all four studies side effects were more frequent with piperazine than with levamisole. Levamisole was found to be a well-tolerated, highly effective single-dose ascaricide. It should prove to be particularly useful for mass chemotherapy in Ascaris control programs.

Adolescent↗
PubMed1978

Increase of the gluconeogenic and decrease of the glycolytic capacity of rat liver with a change of the metabolic zonation after partial hepatectomy.

During the first 72 h after 67% partial hepatectomy of female Wistar rats (160 g) the specific activities [mumol X min-1 X (g liver)-1] of the glucogenic glucose-6-phosphatase and fructose-bisphosphatase and of the glycolytic hexokinase and 6-phosphofructokinase remained essentially constant. However, the activity of the glycolytic pyruvate kinase (L- plus M2-type) was decreased slightly and that of glucokinase was decreased markedly to below 30%, while the glucogenic phosphoenolpyruvate carboxykinase was increased to over 200%. Between 10 and 40 h after partial hepatectomy, when the proliferation started in the periportal area, a shift of the glucogenic glucose-6-phosphatase-rich zone from its normal periportal to an intermediate or even perivenous position was observed histochemically. After 48 h, when the proliferation was no longer restricted to the periportal zone, the normal glucose-6-phosphatase zonation (as before partial hepatectomy) was restored. Glycogen was degraded rapidly during the first 4 h after operation; it was later repeatedly resynthesized and degraded in correlation with the feeding rhythm of the animals. The zonation of glycogen metabolism was in accord with the observed zonation of glucose-6-phosphatase.

Animals↗