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Biomedical subjects

O Sperling

Publications and source records attributed to O Sperling.

At least 91 records · Page 5Linked to original sources
PubMed1982

Differences in the activity of adenosine deaminase and of purine nucleoside phosphorylase and in the sensitivity to deoxypurine nucleosides between subpopulations of mouse thymocytes.

The activities of adenosine deaminase (ADA) and of purine nucleoside phosphorylase (PNP) were measured in thymocyte subpopulations separated by peanut agglutinin (PNA), in unseparated thymocytes, in lymph node and in spleen cells. The PNA+ thymocyte subpopulation exhibited the highest ADA activity of all cells studied. The lowest PNP activity was found in the PNA- subpopulation of thymocytes. PNA+ cells, moreover, exhibited a more intensive DNA synthesis than the PNA- cells, and a greater sensitivity to deoxyadenosine toxicity in the presence of erythro-9-(2-hydroxy-3-nonyl)-adenine (EHNA). The two thymocyte subpopulations exhibited a similar sensitivity to deoxyguanosine (dG) toxicity.

Adenine↗
PubMed1981

Lesch-Nyhan syndrome in an Arab family. Detection and biochemical manifestation of heterozygosity.

A large Arab family affected with the rare X-linked Lesch-Nyhan syndrome is reported on. Two hemizygous boys, two and nine years of age, had the classical biochemical and clinical-neurological syndrome. The activity of erythrocyte hypoxanthine-guanine phosphoribosyltransferase (HGPRT) was below the detectable limit (greater than 0.1% of normal). They were mentally and physically retarded and exhibited spasticity and choreoathetosis; the older of the two also exhibited self-mutilation. The mother and three of her seven daughters, all clinically asymptomatic, were proven to be heterozygous for HGPRT deficiency, by demonstration of an increased rate of de novo purine synthesis in cultured skin fibroblasts. Erythrocyte HGPRT activity was normal in the three heterozygous daughters, but was significantly reduced in the mother. However, in all four heterozygotes, erythrocyte HGPRT/adenine phosphoribosyltransferase ratio was lower than in all other family members. All heterozygotes had blood uric acid levels within the normal range, although higher than in the normal women in the family. The ratio uric acid/creatinine concentration in the urine was significantly elevated in one of the heterozygotes, and in the upper normal limit in two others, indicating excessive purine production.

Adolescent↗
PubMed1980

Hereditary renal hypouricemia. Isolated tubular defect of urate reabsorption.

A consanguineous Iraqi Jewish kindred is presented in which asymptomatic and apparently benign hypouricemia, secondary to an isolated renal defect, segregates as an autosomal recessive trait affecting four of eight siblings. The 8-year-old proband was ascertained during an evaluation for an apparently unrelated inherited neurologic disorder with which an older normouricemic sibling was also affected. Urate clearance in three affected siblings was 22.6, 35.2, and 60.8 ml/minute, while that in normouricemic siblings was 8.6 to 10.6 ml/minute. Pyrazinamide administration to one affected sibling reduced the urate clearance from 61 to 14.7 ml/minute. A recessively inherited single gene lesion producing a tubular defect is postulated; the exact site(s) is uncertain.

Adolescent↗
PubMed1980

De novo synthesis of purine nucleotides in human blood platelets.

Human blood platelets were found to carry the complete pathway of de novo purine nucleotide synthesis. The rate of purine synthesis was gauged by the rate of incorporation of precursor (14C)formate into purines. The effect on formate incorporation of several compounds known to inhibit purine synthesis de novo was studied. Adenine, orotic acid and azaserine inhibited purine synthesis, but hypoxanthine and allopurinol did not. Platelet content of phosphoribosylpyrophosphate (PRPP) and of ribose-5-pes. Incubation of intact platelets with high inorganic phosphate concentrations caused an increase in platelet PRPP content but did not affect R-5-P content or the rate of purine synthesis de novo.

Adenine↗
PubMed1980

Characterization of purine nucleotide metabolism in cultured fibroblasts with deficiency of hypoxanthine-guanine phosphoribosyltransferase and with superactivity of phosphoribosylpyrophosphate synthetase.

Cultured fibroblasts with hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency exhibited acceleration of purine synthesis de novo, absence of salvage IMP synthesis from hypoxanthine, but normal total IMP synthesis. Cells with phosphoribosylpyrophosphate synthetase superactivity exhibited acceleration of both de novo and salvage IMP synthesis and increased total IMP synthesis. The study of mutant cells furnished evidence that in normal as well as mutant cells, GMP and AMP are not converted to each other in significant amounts and that these nucleotides are not degraded by nucleotidases. Purine nucleotide degradation in fibroblasts occurs mainly by dephosphorylation of IMP. In HGPRT-containing cells, salvage IMP synthesis from preformed and exogenously supplied hypoxanthine is the main source for IMP production.

Cells, Cultured↗
PubMed1980

Activity of adenosine deaminase and of purine nucleoside phosphorylase in peripheral lymphocytes from patients with acquired immunological disorders.

The activity of adenosine deaminase (ADA) and of purine nucleoside phosphorylase (PNP) was determined in the peripheral lymphocytes of patients with diseases associated with acquired partial dysfunction of the immune response. Increase ADA activity was found in patients with Waldenstrom's macroglobulinemia and in some patients with non-Hodgkin's lymphoma. Increased PNP activity was found in patients with non Hodgkin's lymphoma whereas decreased PNP activity was fund in patients with connective tissue disorders. The alternations found in ADA and PNP activities probably reflect changes in the lymphocyte subpopulations and do not seem to have an etiological role in the pathogenesis of the disturbed immune response.

Adenosine Deaminase↗
PubMed1979

Familial renal hypouricaemia: two additional cases with uric acid lithiasis.

Two families are reported affected with hereditary renal hypouricaemia associated with uric acid lithiasis. The propositi of both families were found also to have hyperabsorptive hypercalciuria. Based on the study of the effect of pyrazinamide and probenecid on uric acid excretion in both propositi, it is suggested that the defect in uric acid reabsorption is most probably at the pre-secretory site.

Adult↗
PubMed1979

Increased de novo purine synthesis in cultured skin fibroblasts from heterozygotes for the Lesch-Nyhan syndrome. A sensitive marker for carrier detection.

The metabolic consequence of hypoxanthine-guanine phosphoribosyltransferase deficiency, the accelerated rate of purine synthesis de novo, was utilized as a marker for the detection in cultured fibroblasts of heterozygosity for the Lesch-Nyhan syndrome. This marker was found to be very sensitive allowing the detection of mutant cells in nonselected mixed mutant: normal cell cultures even at low proportion of 1 to 10. Exposure of the mixed cultures to selection for the mutant cell with azaguanine increased the sensitivity of the test. Cultures from different biopsies, obtained from heterozygote females, were found to contain different proportions of the mutant cell, ranging from 10 to 84%.

Cells, Cultured↗