Search PubMed⌕ Search

Biomedical subjects

N Katz

Publications and source records attributed to N Katz.

At least 217 records · Page 12Linked to original sources
PubMed1978

[Vertebrate hormones influence on the reproduction of Biomphalaria glabrata and on Schistosoma mansoni infection (author's transl)].

The influence of fifteen vertebrate hormones on the B. glabrata reproduction and on S. mansoni infection have been studied. Hecogenine and pregnadienolone significantly increased the snail's number of eggs; testosterone, diethylstilbestrol and estradiol valerianate decreased their number of eggs and the mesterolone and progesterone produced a slight decrease in the number of eggs. Crude hecogenine, pregnenolone, prednisone, estradiol, cholic acid, diosgenin, estrone and pregnadione have not shown any significant alteration on the snail reproduction. None of these hormones presented any influence upon the S. mansoni cycle in B. glabrata. Molluscicidal, oocidal and cercarcidal activities have been observed with diethylstilbestrol in concentrations below 10 ppm.

Animals↗
PubMed1977

Electron microscopy of a feminizing Leydig cell tumor of the testis.

The ultrastructural characteristics of a feminizing interstitial (Leydig) cell tumor of the testis were compared with those of normal Leydig cells and with the findings described in 10 published cases of Leydig cell tumor. The neoplastic Leydig cells superficially resembled normal Leydig cells. Similarities included abundant smooth endoplasmic reticulum, lipid, and microbodies. Contrastingly, Reinke crystalloids and paracrystalline inclusions were absent and lipochrome pigment and lysosomes very rare. The nuclei were large and contained enlarged, often multiple, nucleoli. The nuclear membranes tended to be irregular and undulating. Cytoplasmic membranous whorls and myelin figures were conspicuous. Fairly homogeneous fibrous septa were evident between single and grouped tumor cells. Despite several individual variations, there is a general resemblance between the neoplastic Leydig cells in this patient and those previously reported. No distinguishing ultrastructural characteristics were discerned between feminizing and virilizing Leydig cell tumors.

Adult↗
PubMed1977

Effects of a feminizing testicular Leydig cell tumour on nontumorous testicular tissue: an ultrastructual study.

The ultrastructural effects of a Leydig cell tumour of the testis on nontumorous testicular tissue have not yet been reported. Described here are the electron microscopic findings in the nonneoplastic testicular tissue of a patient with a feminizing testicular Leydig cell neoplasm. Serial studies were carried out over a period of 31/2 years prior to removal of the tumour. The overall general picture was characterized by progressive degeneration of Leydig cells, cells of the germinal series and Sertoli cells. Concomitantly, there was increasing thickening and fibrosis of the tubular walls. Cytoplasmic focal accumulations of glycogen, increasing with the duration of the disease, were conspicuous in many spermatogonia. All of these alterations are nonspecific and are attributable to adverse endocrine effects introduced by the oestrogen-secreting tumour. They were present bilaterally and were more prominent on the tumour-bearing side. Attention is drawn to the role of artifacts, fixation technique and degenerative processes in the production and appearance of certain ultrastructural findings, such as 'light' and 'dark' cells, myelin figures, membranous whorls and focal glycogen accumulations.

Adult↗
PubMed1977

Field trials with oxamniquine in a Schistosomiasis mansoni-endemic area.

In Peri-Peri (Minas Gerais), an area endemic for Schistosoma mansoni, 591 inhabitants were examined. A coprological survey showed a prevalence of infection of 43.7%. After clinical examination 220 patients were distributed into three groups for treatment with oxamniquine; in Group 1, 19 children (2 to 15 years) were treated with a single oral dose of drug suspension around 20 mg/kg body weight; in Group 2, 47 children were treated orally with two 10 mg/kg doses with a 6- to 8-hour interval between them; in Group 3, 154 adults were treated with a single dose of about 15 mg/kg (capsules). The most frequent side effects were dizziness, drowsiness, and headache. No statistical difference in frequency of side effects was observed between Groups 1 and 2. Nevertheless, after treatment 32% of the patients in Group 1 complained of dizziness and 13% of headache, whereas in Group 2 the frequencies of these symptoms were 2% and 0%, respectively. Adults (Group 3) had a higher frequency of side effects, their chief complaints being dizziness and drowsiness. In Groups 1, 2, and 3, respectively, 73.7%, 62.2%, and 82.4% of the patients were cured. Statistical analysis did not show any difference in cure rates between children in Groups 1 and 2; however a significance was found when compared with the cure rate observed in adults, showing the drug to be more active in the latter group. In 61.8% of the 40 patients not cured a decrease of over 90% in the number of S. mansoni eggs/g feces was observed. From the data above oxamniquine seems to be an effective schistosomicidal drug suitable for use in endemic areas, although further studies are still needed.

Adolescent↗
PubMed1976

Autoregulatory shift from fructolysis to lactate gluconeogenisis in rat hepatocyte suspensions. The problem of metabolic zonation of liver parenchyma.

Hepatocytes were isolated from fed rats with glucose and insulin and freom fasted rats with glucagon in all media in an attempt to obtain cells which might be fixed preferentially in either the glycolytic or gluconeogenic state. When tested enzymatically, both "fed" and fasted" cells catalyzed glucose formation from lactate (gluconeogenesis) and lactate formation from fructose (fructolysis); lactate formation from glucose may have occurred in "fed" cells. Thus it was impossible, at least in the C3 part of the metabolic pathways between triosephosphate and pyruvate, to fix the hepatocytes in either metabolic state. The shift from glycolysis to gluconeogenesis could be investigated for the C3 part in "fasted" cells with fructose as the glycolytic and lactate as the gluconeogenic substrate. Lactate was first formed from fructose and later reutilized to a large extent. This reconsumption was blocked by the gluconeogenesis inhibitor quinolinate, both when tested enzymatically and radiochemically. Thus fructolysis was shifted to lactate gluconeogenesis. This shift at the assumed phosphoenolpyruvate/pyruvate cycle was autoregulatory, i.e. dependent on substrates and independent of circulating horomes. Maximal velocities and half saturating concentrations were determined for fructose and for lactate as substrates. The kinetic data obtained, especially the sigmoidal pattern of fructolysis, could nicely explain phenomenologically the rather sudden slow-down of lactate production and the shift to lactate consumption. The levels of the metabolites ATP, ADP, AMP, fructose bisphosphate and alanine, which control the enzymes of the assumed phosphoenolypyruvate/pyruvate cycle, were determined in the cytosol and in the mitochondria before and after the shift from fructose glycolysis to lactate gluconeogenesis. The changes observed could not explain the shift. Experiments with [14C] fructose plus unlabelled lactate and reciprocally, with unlabelled fructose plus [14C] lactate, clearly reveled that within the C3 part, glycolysis and gluconeogenesis were catalyzed simultaneously. The simultaneity of and the shift between fructolysis and gluconeogenesis by the liver cell suspension can best be explained by assuming two metabolically different types of hepatocytes rather than one type of hepatocyte with metabolically equal or different cell compartment. In vivo, the different types of hepatocytes would form a gluconeogenic and a glycolytic zone within the liver parenchyma. Since, under normal conditions, the size of these metabolic zones should remain unaltered, the shift from net glycolysis to net gluconeogenesis would be dependent primarily on substrate concentrations (autoregulation).

Adenine Nucleotides↗
PubMed1975

Clinical evaluation of niridazole and hycanthone in schistosomiasis mansoni endemic areas.

One hundred patients with active schistosomiasis mansoni were treated with niridazole (25 mg/kg/day po for 7 days). The most serious side effects were those connected with the neuropsychic area (convulsion, hallucination, etc.). Therapeutic activity, based on repeated stool examinations, was about 90% in adults and 60% in children. Because of the side effects, as well as the long-term schedule of treatment, niridazole is not recommended for use under field conditions. Seven hundred and forty-five patients were treated with hycanthone (2.5 mg/kg im) after clinical examination. The side effects observed were mild and of short duration (24-48 hr). The therapeutic activity was very high (about 95% cure). So far we have treated more than 9,000 infected patients without severe complications, including hepatic failure and death, which have been reported by some authors. A hycanthone-resistant strain has been isolated from two patients unsuccessfully treated twice with hycanthone and once with niridazole. Considering that an important aspect of the control of schistosomiasis is mass treatment, further studies regarding mutagenicity, teratogenicity, resistance, and toxicological effects of hycanthone are still required before this drug can be recommended for wide use.

Adult↗
PubMed1975

Histidines and renal function.

The results of endogenous renal clearances of 3-methylhistidine and histidine in twelve patients with normal and decreased renal functions are reported. Differences in the renal handling of the amino acids have been established. 3-methylhistidine showed a hyperbolic relationship between serum concentration and inulin clearance: histidine a linear relationship. The percentage tubular reabsorption of 3-methylhistidine was found to be about half that of histidine. The possible use of the measurement of serum 3-methylhistidine concentration as an index of renal insufficiency is discussed.

Adult↗
PubMed1975

Histidine and iron supplementation in dialysis and pre-dialysis patients.

Chronic renal failure (CRF) patients treated with histidine alone did not show any effect with respect to anaemia or protein metabolism, despite a rise in serum histidine levels. Beneficial effect of iron with regards to anaemia and protein metabolism was seen in CRF patients treated with iron alone or in combination with histidine. Patients with combination therapy showed accelerated improvement of anaemia in comparison with patients treated with iron alone. In RDT patients, who underwent basic treatment with parenteral iron, histidine failed to show any effect with regards to anaemia, despite significantly lowered serum histidine levels. But under histidine treatment a significant rise of transferrin levels occurred in RDT patients, so that histidine must be considered as a limiting factor in protein metabolism in these cases. Histidine requirements of RDT patients are more than 1-2 g/day, and are higher than the requirements of patients conservatively treated.

Histidine↗
PubMed1975

Amino acid and protein intake in RDT patients. A nutritional and biochemical analysis.

In 40 unselected RDT patients (20 center and 20 home dialysis patients) the intake of nutrients was measured using the precise weighing method of Wirths [1969]. The protein intake was found to be 0.97 plus or minus 0.19 g/kg predialysis body weight, the calorie intake 32.3 plus or minus 6.4 cal/kg. Two thirds (0.65 plus or minus 0.15 g/kg) of the protein consisted of high biological value protein. Despite the fact that according to current recommendations the protein intake should have been adequate, signs of protein malnutrition were found. The mean serum concentrations of total protein, transferrin and valine and the ratio of essential amino acids to nonessential amino acids (EAA/NEAA) were significantly lower than in normal subjects and the glycine level was elevated. Histidine levels were normal indicating that the histidine intake measured at 1.75 plus or minus 0.47 g/day appeared adequate under these conditions. Phenylalanine levels were elevated indicating a blocking of 4-hydroxylase leading to low tyrosine levels. A possible reason for these findings may be that the protein requirements of the RDT patient over a long period of time are higher than those found experimentally in short term studies. An inadequate calorie intake could not be excluded. Additionally a dialysis dependent pathologic variation of the daily intake of nutrients may be responsible for the disturbed nutritional status. In connection with this, three distinct types of intake variation can be described: A stable type in which the variation in the daily protein and calorie intake does not differ by more than 20% from a daily mean value, an unstable type I with significantly lower intake on the day of dialysis and an unstable type II with a significantly higher intake on the day of dialysis. Signs of protein malnutrition occurred significantly more frequently in the unstable groups.

Adult↗