PubMed Health⌕ Search

Biomedical subjects

S Yatziv

Publications and source records attributed to S Yatziv.

At least 19 recordsLinked to original sources
PubMed1990

Glycosidase activities of mycoplasmas.

The activities of alpha- and beta-glucosidase, beta-galactosidase and beta-N acetylglucosaminidase were assessed at acidic pH by fluorimetry using the appropriate 4-methylumbelliferyl substrate in four Mycoplasma species (M. pneumoniae, M. gallisepticum, M. hominis and M. capricolum) and in Acholeplasma laidlawii. The glycosidase activities were in a low range (0.1-4.2 nmole per h per mg protein) with the exception of higher activities of beta-N-acetylglucosaminidase in A. laidlawii. The enzyme levels of a virulent and a nonvirulent strain of M. pneumoniae were comparable. Despite the very sensitive assay, neuraminidase activity was not detected in M. pneumoniae and M. gallisepticum. No induction of alpha-glucosidase could be demonstrated for M. pneumoniae or A. laidlawii. At least part of the glycosidase activities was localized in the membrane fraction of all mycoplasmas studied. This may support the hypothesis that pathogenic mycoplasmas, being membrane parasites, may modify, by their glycosidases, some host cell glycoconjugates. However, our study did not distinguish the pathogenic mycoplasmas to possess a characteristic glycosidase profile.

Acetylglucosaminidase↗
PubMed1990

Turnover of proteoglycans in skin fibroblast cultures derived from patients with mucopolysaccharidoses.

The turnover of proteoglycans in the extracellular matrix was studied in fibroblasts cultures derived from patients with mucopolysaccharidosis (MPS) and healthy donors. The cells were labelled with 35S-sulfate and 14C-glucosamine and it was found that in MPS-fibroblasts the rate of extracellular matrix turnover was hardly affected, where as the intracellular turnover was severely inhibited. Similar results were obtained with normal fibroblasts treated with 20 mM ammonia. Autoradiography revealed that MPS fibroblasts have a preferential accumulation of 35S-sulfate labelled material in the nuclear area, indicating that the nucleus may also be affected in MPS pathology. It is suggested that, although lysosomal enzymes are an important factor in intracellular proteoglycan turnover, they do not play a crucial role in the turnover of extracellular matrix proteoglycans.

Autoradiography↗
PubMed1989

Propionic acidemia--biochemical studies.

The first documented case of propionic acidemia in Israel is described. Diagnosis was based on three independent methods: analysis of urinary organic acids by gas chromatography/mass spectrometry, assay of propionyl CoA carboxylase activity and oxidation of 1-14C-propionate by cultured skin fibroblasts. The use of more than one method for confirmation of the diagnosis is considered to be of importance in providing an additional margin of safety in cases where genetic counseling and prenatal diagnosis in future pregnancies are indicated.

Ammonia↗
PubMed1988

Macrophages exposed in vitro to conduritol B epoxide resemble Gaucher cells.

In Gaucher disease the genetic lack of acid beta-glucosidase activity causes glucocerebroside to accumulate in the lysosomes of macrophage-derived cells, producing large characteristic Gaucher cells. The formation of Gaucher cells seems to be central to the pathobiology of this lysosomal storage disease. To develop a model simulating this process, cultured murine peritoneal macrophages were treated with conduritol B epoxide, a specific irreversible inhibitor of acid beta-glucosidase, for 6, 15, and 24 days. The conduritol B epoxide-treated macrophages accumulated glucocerebroside as a function of time, progressing to a fivefold elevation over control values after 24 days of treatment. Electron microscopy of the cells treated for 24 days reveals characteristics of Gaucher cells, including striations consisting of oriented fibrils. With conventional staining techniques, these fibrils have an appearance considered highly characteristic of Gaucher disease. Thus, macrophages treated with conduritol B epoxide are a useful model for studying the metabolic consequences and morphologic features associated with glucocerebroside accumulation in Gaucher cells.

Animals↗
PubMed1988

Gaucher-like changes in human blood-derived macrophages induced by beta-glucocerebrosidase inhibition.

Human blood-derived macrophages were cultured in the presence of conduritol-B-epoxide, a specific inhibitor of beta-glucosidase, to induce changes resembling those occurring in the cells of patients with Gaucher's disease. After 24 hours of incubation, only 5% of the original beta-glucosidase activity remained; on removal of the inhibitor, the enzyme activity recovered almost fully to control levels after 5 days. After 30 days of incubation with conduritol-B-epoxide, the macrophages contained almost 10 times as much glucocerebroside as the untreated controls, and the cells displayed morphologic changes reminiscent of Gaucher's cells. This in vitro system may enable detailed studies on the pathogenetic mechanisms associated with glucocerebroside accumulation in human macrophages as well as on the turnover of the accumulated substrate and reversal of the morphologic abnormalities on removal of the inhibitor.

Blood Cells↗
PubMed1986

beta-Glucosidase inhibition in murine peritoneal macrophages by conduritol-B-epoxide: an in vitro model of the Gaucher cell.

Murine peritoneal macrophages were cultured in the presence of conduritol-B-epoxide, a specific covalent inhibitor of beta-glucosidase. The inhibition was found to be dose and time dependent. Upon removal of the inhibitor from the culture medium, beta-glucosidase activity recovered to half maximum by 2.2 days. Treatment of macrophages with this inhibitor for 15 days did not affect cell viability, lysosomal enzyme release to the medium, or levels of intracellular lysosomal enzymes, other than beta-glucosidase activity. This inhibition results in the accumulation of glucocerebroside. In vitro studies on the pathobiology of such macrophages whose beta-glucosidase activity has been reduced may be useful toward understanding the pathogenesis of Gaucher disease.

Animals↗
PubMed1986

Parameters affecting the in vitro maturation of human monocytes to macrophages.

In vitro maturation of human monocytes to macrophages was characterized by morphological criteria, cell size and lysosomal enzymes activity. Purified populations of monocytes were maintained in culture at either adherent or nonadherent conditions and their maturation to macrophages was observed in both cases. The addition of external factors such as hydrocortisone and vitamin D3 inhibited monocyte maturation. In the absence of external factors, nonadherent monocytes were inhibited in their maturation for up to 10 days when plated at crowded cell concentrations. In addition, the presence of human serum in the culture media had a higher inhibitory activity than similar concentrations of fetal calf serum. Supernates from crowded macrophages were also inhibitory for monocyte maturation. We suggest the possibility that cell crowding, as well as soluble factors found in the serum and probably secreted by macrophages, participate in the regulation of monocyte development by inhibiting their maturation. Once released from this inhibitory signal or environment, the monocytes mature to macrophages.

Adolescent↗
PubMed1986

Calcification of intervertebral disks in I-cell disease.

I-cell disease (ICD) is associated with skeletal dysplasia. However, changes of the intervertebral disks had not been previously reported. We describe a child with clinical and laboratory evidence of ICD who had multiple intervertebral disk calcifications. Since an excessive degeneration of the cartilage had previously been found in ICD, we propose that this process may give rise to calcification of the intervertebral disks in patients with ICD.

Calcinosis↗
PubMed1986

Protective effects of the glutathione redox cycle and vitamin E on cultured fibroblasts infected by Mycoplasma pneumoniae.

The role of the glutathione (GSH) redox cycle and vitamin E as antioxidant defense systems was studied in normal human cultured skin fibroblasts infected by virulent Mycoplasma pneumoniae. In cells infected for 20 h, catalase activity was inhibited by 75% and the intracellular GSH decreased to 32% of its normal values. GSH peroxidase and oxidized glutathione (reductase activities in the infected cells were unaffected.) GSSG glutathione in the medium of the infected cells rose in accordance with the intracellular GSH decrease. The observed elevation in GSSG/GSH ratio was attributed to the increase in intracellular H2O2 content in M. pneumoniae-infected cells due to the marked inhibition in their catalase activity. The protective effect of the GSH redox cycle in infected cells was studied by depletion of cellular GSH, prior to their infection with M. pneumoniae, using buthionine sulfoximine (BSO), a selective inhibitor of gamma-glutamyl cysteine synthetase. After 16 h of incubation with BSO, the GSH levels were reduced to 38% of their normal value and recovered to 55% during 24 h after removal of the inhibitor. BSO had no effect on GSH peroxidase and catalase activities in either infected or noninfected cells. The level of malonyldialdehyde (an indicator of membrane lipid peroxidation) in BSO-treated cells infected by M. pneumoniae was 1.8 times higher than in infected controls. Cells enriched with 0.25 and 2.25 micrograms of vitamin E per mg of protein prior to their infection by M. pneumoniae revealed the following: a lesser degree of catalase inhibition, 46 and 30%, respectively, versus 64% in infected control cells that were not supplemented with vitamin E; lower levels of malonyldialdehyde, 55 and 20% increments, respectively, versus a 140% increment in infected controls; higher residual activity of lactate dehydrogenase, 76 and 96%, respectively, versus 58% in infected controls. Our data indicate that the oxidative damage induced in M. pneumoniae-infected cells due to the increase in intracellular levels of H2O2 and O2- is limited by the host cell GSH redox cycle and by supplementation with vitamin E.

Buthionine Sulfoximine↗
PubMed1986

Lysosomal hydrolases in blood-derived macrophages of patients with I-cell disease.

Three lysosomal hydrolases, beta-galactosidase, beta-glucuronidase, and beta-N-acetylglucosaminidase, were examined in blood-derived macrophages and media of two patients with I-cell disease. The activities of the three enzymes were lower in I-cell macrophages than in normal controls. However, the media collected from these cells possessed higher activities than control media. beta-N-acetylglucosaminidase derived from media of I-cell macrophages was not endocytosed by fibroblasts from patients with Sandhoff's disease and was only partially endocytosed by I-cell macrophages. These findings indicate that blood-derived macrophages of patients with I-cell disease are affected. In addition, the data presented suggest the presence of two types of receptors in human blood-derived macrophages: mannose and mannose-6-phosphate.

Acetylglucosaminidase↗
PubMed1986

Termination of absence status and suppression of inter-ictal bursts with phenytoin: case report.

An 11 year old female with a first episode of absence status is described. Clinical manifestations, ictal and post-ictal EEGs were generalized. An IV loading dose of phenytoin resulted in an abrupt cessation of both clinical and EEG ictal phenomena, and later was found to be effective in suppressing inter-ictal bursts of 3 per second spike and slow wave discharges. This response is unusual since phenytoin is considered ineffective in controlling petit mal epilepsy.

Child↗
PubMed1986

Clinical and laboratory study in 22 patients with inherited hyperammonemic syndromes.

Twenty-two patients with inherited hyperammonemic syndromes are presented. These patients represent 22 different families. The diagnosis was based mainly on family history, blood ammonium levels, acid base balance, urinary orotic acid, urinary and plasma amino acids and organic acids. The final diagnosis was confirmed by determination of liver enzyme activity. In 12 patients (54%), the first clinical manifestations were noticed after the neonatal period; 7 patients (31%) were diagnosed after infancy, and 8 (23%) after the age of 8 years. Two patients who represent the late-onset group of inherited hyperammonemic syndromes are presented in detail. The three most common diagnoses were ornithine transcarbamoylase deficiency, carbamoyl phosphate synthetase deficiency, and lysinuric protein intolerance, which comprised 59% of the diagnosed patients. Our data, based on one of the largest series reported, reveal a relatively large percentage of late-onset inherited hyperammonemic syndromes as compared with previous reports.

Amino Acid Metabolism, Inborn Errors↗