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Biomedical subjects

O Sperling

Publications and source records attributed to O Sperling.

At least 73 records · Page 4Linked to original sources
PubMed1986

Lactate dehydrogenase isoenzymes in serum during unstable angina.

Values for total lactate dehydrogenase (LD, EC 1.1.1.27) activity in serum, LD isoenzymes 1 and 2, and the LD 1:2 ratio in 25 patients with unstable angina were compared with the same variables in 25 patients whose angina was stable 24, 48, and 72 h after admission. Mean total LD activity and mean LD-2 activity were found to be within the normal range, both in the unstable angina and stable angina groups of patients. In the unstable angina group the mean LD-1 was significantly higher (p less than 0.01) than in the stable angina group at each time studied. The mean LD 1:2 ratio was also significantly different (p less than 0.001) between the two groups of patients. In the unstable angina group of patients the ratio was increased (0.85, SD 0.09), as in patients with acute myocardial infarction, whereas in the stable angina group of patients the ratio was normal (0.60, SD 0.06). We conclude that a high LD 1:2 ratio, even in the presence of normal total LD activity, may indicate myocardial damage in some patients with unstable angina and could therefore help in the clinical and functional evaluation of patients with unstable angina.

Adult↗
PubMed1984

Characterization of purine nucleotide metabolism in primary rat cardiomyocyte cultures.

Primary rat cardiomyocyte cultures were utilized as a model for the study of purine nucleotide metabolism in the heart muscle, especially in connection with the mechanisms operating for the conservation of adenine nucleotides. The cultures exhibited capacity to produce purine nucleotides from nonpurine molecules (de novo synthesis), as well as from preformed purines (salvage synthesis). The conversion of adenosine to AMP, catalyzed by adenosine kinase, appears to be the most important physiological salvage pathway of adenine nucleotide synthesis in the cardiomyocytes. The study of the metabolic fate of IMP formed from [14C]formate or [14C]hypoxanthine and that of AMP formed from [14C]adenine or [14C]adenosine revealed that in the cardiomyocyte the main flow in the nucleotide interconversion pathways is from IMP to AMP, whereas the flux from AMP to IMP appeared to be markedly slower. Following synthesis from labeled precursors by either de novo or salvage pathways, most of the radioactivity in purine nucleotides accumulated in adenine nucleotides, and only a small proportion of it resided in IMP. The results suggest that the main pathway of AMP degradation in the cardiomyocyte proceeds through adenosine rather than through IMP. About 90% of the total radioactivity in purines effluxed from the cells during de novo synthesis from [14C]formate or following prelabeling of adenine nucleotides with [14C]adenine were found to reside in hypoxanthine. The activities in cell extracts of AMP 5'-nucleotidase and IMP 5'-nucleotidase, which catalyze nucleotide degradation, and of AMP deaminase, a key enzyme in the purine nucleotide cycle, were low. The nucleotidase activity resembles, and that of the AMP deaminase contrasts the respective enzyme activities in extracts of cultured skeletal-muscle myotubes. The results indicate that in the cardiomyocyte, in contrast to the myotube, the main mechanism operating for conservation of nucleotides is prompt phosphorylation of AMP, rather than operation of the purine nucleotide cycle. The primary cardiomyocyte cultures are a plausible model for the study of purine nucleotide metabolism in the heart muscle.

5'-Nucleotidase↗
PubMed1984

Cardiomyocytes cultured in serum-free medium. Growth and creatine kinase activity.

Primary cultures of newborn rat heart cells were grown for up to 3 weeks in serum-free medium supplemented by insulin, hydrocortisone, transferrin and fetuin. The cells resumed spontaneous beating at 20 h post plating. Mean rates of beating on the second and third day were 79.5 and 94 beats per min, respectively. Cell proliferation occurred during the first 3 days of culture with maximal rates of DNA and protein synthesis on the second day. The highest values of creatine kinase activity were observed on days 2-5 and the three cytoplasmic isozymes, MM, MB and BB, were present in the cultures in proportions similar to those of the newborn heart, indicating stability of the differentiated state of the cells. The relative amount of each isozyme remained unchanged throughout the experiments, MM constituted 70-90% of enzyme activity, MB contributed up to 30% and BB did not exceed 15% of activity. The very low proportion of BB and the lack of increase in this isozyme with age of culture support our earlier morphological observations that non-myocytes do not overgrow the culture.

Animals↗
PubMed1984

Adenosine deaminase activity in lymphocyte subpopulations of B-16 melanoma and normal C57BL bearing mice.

The activity of adenosine deaminase (ADA) was measured in thymus and spleen subpopulations separated by peanut agglutinin (PNA) of melanoma B-16 C57BL bearing mice and normal age-matched C57BL mice. Groups of 10 mice were used each time and the experiments were repeated 6 times. The adenosine deaminase activity in the PNA+ thymocytes of B-16 bearing mice was about 2.5 times lower than that of the normal C57BL mice while the ADA activity in the PNA+ fraction of spleen of the B-16 melanoma bearing mice was 2.5 times higher. These results demonstrate that the tumor burden probably induces a different redistribution and traffic of lymphocytes from one lymphopoietic organ to another. This traffic can also explain the thymus involution and spleen enlargement found in the B-16 mice.

Adenosine Deaminase↗
PubMed1984

The activities of enzymes of purine metabolism in murine thymus dependent lymphocytes.

Measurement of the activities of purine metabolizing enzymes in murine T cell subpopulations showed that these activities differed markedly among T cells of different levels of functional maturity. The activities of adenosine deaminase and deoxyadenosine phosphorylation were highest in immature, PNA + thymocytes, while the activities of purine nucleoside phosphorylase, ecto-5'-nucleotidase and deoxyguanosine phosphorylation were highest in mature, splenic T cells. These enzymes' activities can be used as biochemical markers for T cell of different degree of maturation.

5'-Nucleotidase↗
PubMed1984

Lesch-Nyhan syndrome: biochemical characterization of a case with attenuated behavioral manifestation.

The activity and kinetic properties of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) were studied in fibroblasts from a Lesch-Nyhan syndrome (LNS) variant, with complete HGPRT deficiency in hemolysates, but with attenuated behavioral manifestation of the syndrome. The mutant HGPRT exhibited a 100-fold increase in Km for substrate phosphoribosyl-pyrophosphate, manifest in markedly decreased enzyme activity, being 2.5% of normal in cell extracts and about 0.6% of normal in intact cells. This degree of residual activity of the mutant enzyme is within the range found in patients with classical LNS.

Adult↗
PubMed1984

Low serum creatine phosphokinase values in patients with acute viral hepatitis.

Low values of serum creatine phosphokinase (CPK) were found in a group of 27 patients suffering from acute viral hepatitis. The values were significantly lower than CPK values in a group of 25 patients with extra hepatic obstructive jaundice (23.3 +/- 32.1 versus 163 +/- 43 U/L, p less than 0.001). CPK values in the hepatitis group when recovered (6 months after hospitalization) were much higher than the mean CPK levels in the same group during the acute illness (178 +/- 28 versus 23.3 +/- 32.1 U/L, p less than 0.001) and were the same as a control group of 26 healthy volunteers (179 +/- 28 versus 179 +/- 20.9 U/L). Similar results were found when the groups were divided into separate male and female groups. Serum CPK values, thus, were found to be a useful diagnostic tool to distinguish between patients with intrahepatic jaundice due to acute viral hepatitis and patients with extra hepatic obstructive jaundice.

Adolescent↗
PubMed1983

Alterations in purine nucleotide metabolism during muscle differentiation in vitro.

Pathways of purine nucleotide metabolism affecting the availability of ATP in the muscle tissue were studied in differentiating rat muscle cultures. The rate of de novo purine nucleotide synthesis and of AMP deamination were found to increase markedly with cell differentiation, but the rate of IMP dephosphorylation was similarly low in both myoblasts and contracting fibers. The above differentiation-associated alterations in purine nucleotide metabolism conform with the greater need for ATP as a source of energy in the contracting myotubes.

AMP Deaminase↗
PubMed1983

Characterization of thymocyte subpopulations by enzymatic markers.

The activities of ecto-5'-nucleotidase (E5N), deoxyadenosine kinase (dAK) and deoxyguanosine kinase (dGK), were determined in thymocyte subpopulations, separated by peanut agglutinin (PNA). The activity of dAK in the PNA+ (agglutinated by PNA) thymocyte subpopulation was 2.5-fold that in the PNA- subpopulation. The activities of E5N and of dKG were found to be higher in the PNA- than in the PNA+ subpopulation by 15- and 4-fold, respectively. The activity of these enzymes can therefore be utilized to characterize the thymocyte subpopulation. In addition, since PNA+ cells are considered to be young immature precursors of the PNA- thymocytes, the activity of these enzymes may serve also as markers for the degree of maturation of the T cells.

5'-Nucleotidase↗
PubMed1982

Effects of fructose on synthesis and degradation of purine nucleotides in isolated rat hepatocytes.

The effects of fructose on purine nucleotide synthesis and degradation were studied in isolated rat hepatocytes. Incubation of the hepatocytes with fructose resulted in deceleration of the rate of de novo purine synthesis, gauged by the rate of incorporation of precusor [14C]formate into total purines produced, and in acceleration of purine nucleotide degradation, as measured by the rate of conversion of prelabelled purine nucleotides into end-product allantoin. These effects were found to be associated with decreases in cellular content of ATP and Pi and in the metabolic availability of 5-phosphoribosyl 1-pyrophosphate. The results support the suggestion that the fructose-induced acceleration of purine degradation is mediated through activation of AMP deaminase. However, the results also suggest that decreased reutilization of hypoxanthine for IMP synthesis, due to the decreased PP-Rib-P availability, is an additional mechanism for the acceleration of purine degradation. The decreased PP-Rib-P availability is also suggested to be the main mechanism for the fructose-induced deceleration of purine synthesis.

Animals↗
PubMed1982

Characterization of purine nucleotide metabolism in primary rat muscle cultures.

The synthesis and metabolic fate of purine nucleotides were studied, employing labeled precursors, in primary rat muscle cultures. The cultures were found to produce purine nucleotides, by de novo and salvage pathways, both exhibiting dependence on cellular availability of substrate 5-phosphoribosyl-1-pyrophosphate (PPRibP). Depletion of cellular PPRibP decelerated the rate of purine synthesis, whereas increasing PPRibP generation by high Pi concentration in the incubation medium, accelerated purine synthesis. Ribose accelerated purine synthesis, indicating that ribose 5-phosphate availability in the cultured muscle is limiting for PPRibP synthesis. The study in the muscle cultures of the metabolic fate if IMP formed from [14C]formate and that of nucleotides formed from labeled purine bases, revealed that the main flow in the nucleotide interconversions pathways is from AMP to IMP. The flow from IMP to GMP and to AMP appeared to be of a lesser magnitude and virtually no flow could be detected from GMP to IMP. The greatest proportion of radioactivity of purine nucleotides following synthesis by either de novo or salvage pathways, accumulated in IMP, reflecting the relative rates of flows between the various nucleotides and probably also a relatively low, or inhibited activity of the IMP nucleotidase. The results suggest that primary muscle cultures are a plausible model for the study of the role of purine metabolism in muscle work.

Adenine↗
PubMed1982

De novo purine synthesis in skeletal muscle.

Myoblast and primary muscle cultures from rat were found to contain the complete pathway of de novo purine nucleotide synthesis. Quantitative assessment of the pathway in skeletal muscle in mice in vivo, revealed a more intensive purine production in muscle than in liver. Skeletal muscle is thus a major site of de novo purine production in the mammalian body.

Animals↗