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S Durham

Publications and source records attributed to S Durham.

62 records · Page 4Linked to original sources
PubMed1981

Production and characterization of monoclonal antibodies to the subunits of human phosphofructokinase: new tools for the immunochemical and genetic analyses of isozymes.

Recently we have demonstrated that human phosphofructokinase (PFK; ATP: D-fructose-6-P, 1-phosphotransferase; EC.2.7.1.11) is under the control of three structural loci that code for M (muscle-type), L (liver-type), and P (platelet-type) subunits: random tetramerization of these subunits produces various isozymes. In this study, we have produced and characterized BALB/c hybridoma antibodies to the M- and L-type subunits of human PFK. The specific antibodies were detected by an enzyme-immunoprecipitation assay using Staphylococci-bearing protein A as an immunoadsorbent. Of the wells tested using red blood cell (RBC) PFK (M + L), 61% were positive. Only one M-specific hybridoma was identified. The one anti-M and 4 anti-L antibodies were characterized for their biochemical and immunochemical specificities. To define the combining specificities of these antibodies, we compared their reactivity and that of monospecific rabbit anti-M antiserum with muscle and liver PFKs from 15 different vertebrate species. The rabbit anti-M shows strong cross-reactivity with the muscle PFKs from all the species studied. In contrast, the monoclonal anti-M reacts exclusively with muscle PFKs from primates. Two of four anti-L antibodies react only with human L-PFK, whereas the other two react with that from a few other vertebrate species as well. Taken together, these data suggest that primate-specific antibodies recognize evolutionarily, recently acquired antigenic determinants, whereas the antibodies reactive with PFKs from distantly related species recognize conserved determinants. The differential immunoreactivities of muscle and liver PFKs strongly suggest the presence of distinct isozymes in all the vertebrate species studied. These studies demonstrate that it is feasible to produce and characterize monoclonal antibodies that distinguish among isozymes with structural and functional similarities. These antibodies provide sensitive tools in the analyses of isozyme structure, genetics, and related fields.

Animals↗
PubMed1980

Sulphasalazine in rheumatoid arthritis.

Seventy-four patients with rheumatoid arthritis were treated with sulphasalazine. There was a significant improvement in clinical score, with substantial falls in serum C-reactive protein concentrations and erythrocyte sedimentation rate four weeks after starting the drug. Improvement was maintained in the 38 patients who remained on the drug for one year. The mean Rose-Waaler titre did not change. There was little difference between the results in seropositive and seronegative patients. The commonest adverse effect was dyspepsia, but five patients developed a megaloblastic anaemia and one patient neutropenia; all made a complete recovery. The results suggest that the drug has a disease-modifying action not attributable to its "salicylate" content. The mode of action might be by an antibacterial effect on gut flora.

Adult↗
PubMed1980

Isozymes of human phosphofructokinase: identification and subunit structural characterization of a new system.

The existence of a five-membered isozyme system for human phosphofructokinase (PFK; ATP:D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) has been demonstrated. These multimolecular forms result from the random polymerization of two distinct subunits, M (muscle type) and L (liver type), to form all possible tetrameters-i.e., M(4), M(3)L, M(2)L(2), ML(3), and L(4). Partially purified muscle and liver PFKs were hybridized by dissociation at low pH and then recombination at neutrality. Three hybrid species were generated in addition to the two parental isozymes, to yield an entire five-membered set. The various species could be consistently and reproducibly separated from one another by DEAE-Sephadex chromatography at pH 8.0 with a concave elution gradient of salt. Under similar experimental conditions, erythrocyte PFK from hemolysates was also resolved into five species chromatographically indistinguishable from those produced in the above experiment. Immunological and kinetic studies of the isozymes provided corroborative evidence to support the proposed subunit structures. Erythrocyte PFK was found to have kinetic properties intermediate between those of muscle and liver PFK and was neutralized only 50% by an antiserum against muscle PFK that completely neutralized muscle PFK. These data demonstrate that muscle and liver PFKs are distinct homotetramers-i.e., M(4) and L(4), respectively-whereas erythrocyte PFK is a heterogeneous mixture of all five isozymes. The structural heterogeneity of erythrocyte PFK provides a molecular genetic basis for the differential organ involvement observed in some inherited PFK deficiency states in which myopathy or hemolysis or both can occur.

Erythrocytes↗
PubMed1980

The molecular mechanism of the inherited phosphofructokinase deficiency associated with hemolysis and myopathy.

Normal human erythrocyte phosphofructokinase (ATP: D-fructose-6, P-1-phosphotransferase, EC 2.7.1.11; PFK) has recently been shown to consist of a heterogeneous mixture of five tetrameric isozymes: M4, M3L, M2L2, ML3, and L4 (M, muscle type; L, liver type). In the light of these findings, we have investigated the molecular basis of the inherited erythrocyte PFK deficiency associated with myopathy and hemolysis (Tarui disease). The propositus, a 31-yr-old male, suffered from muscle weakness and myoglobinuria on exertion. He showed mild erythrocytosis despite laboratory evidence of hemolysis. In his erythrocytes a metabolic crossover point was found at the level of PFK; 2,3-diphosphoglycerate (2,3-DPG) was also significantly reduced. The PFK from the patient's erythrocytes consisted exclusively of the L4 isozyme, and there was a complete absence of the other four. The leukocyte and platelet PFKs from the patient showed normal activities, chromatographic profiles, and precipitation with anti-M4 antibody. These studies provide direct evidence that in Tarui disease the M-type subunits are absent; but the liver- and platelet-type subunits of PFK are unaffected. The paradox of mild erythrocytosis despite hemolysis reflects the decreased production of 2,3-DPG.

Adult↗
PubMedDate not supplied

Biochemical, hematologic, and histopathologic studies in rabbits intrarectally inseminated.

Rabbits subjected three times a week for 7 months to administrations of fresh homologous semen, colonic enemas, or semen (previously frozen at -70 degrees) preceded by enema were monitored by a battery of biochemical and hematologic tests and histopathologic examination. No biochemical, hematologic or histopathologic changes were observed. Negative blood cultures and serum endotoxin determinations excluded any possibility of systemic bacterial infection caused or induced by the treatments. Wide temporary variations in the hematologic parameters, including concentrations of T and B cells, were observed in all treated groups. The relevance of these findings to immune status is not yet certain.

Animals↗
PubMedDate not supplied

Impaired cerebral vasoreactivity after embolization of arteriovenous malformations: assessment with serial acetazolamide challenge xenon CT.

Embolization of a portion of the nidus of an arteriovenous malformation not only may alter hemodynamics within the nidus, but also may change blood flow dynamics in adjacent normal vessels. Sequential acetazolamide-challenge xenon CT cerebral blood flow studies were performed in eight patients before and after embolization of arteriovenous malformations to assess the hemodynamic effects on the major vascular territories supplying the malformation. Acetazolamide is a potent cerebral vasodilator, and its administration combined with cerebral blood flow studies allows assessment of cerebral vasoreactivity. In seven of the eight patients, one or more parenchymal areas exhibited a normal cerebral blood flow augmentation response to acetazolamide before embolization, but diminished acetazolamide flow augmentation was seen after embolization, indicating abnormal vasoreactivity. We found that the decrease in vasoreactivity peaked 6-10 days after embolization. In one of the eight patients, a temporary delayed neurologic deficit developed during a period of impaired cerebral vasoreactivity following embolization. Our results suggest that embolization of an arteriovenous malformation can induce vasoreactivity changes in adjacent normal vessels. Because these changes appear to be somewhat time-dependent, an appropriate interval should be observed between embolization stages or before surgical resection of an arteriovenous malformation following embolization to allow hemodynamic equilibration to occur. Acetazolamide challenge combined with serial cerebral blood flow studies following embolization enables determination of this hemodynamic equilibration.

Acetazolamide↗
PubMedDate not supplied

Effects of taurocholate infusion on biliary excretion in isolated perfused rat livers. Decreased biliary excretion of dibromosulfophthalein in pregnancy.

A crossover experimental design was used to examine the effects of saline (SAL) vs. taurocholate (TC) infusion on hepatic excretory function in isolated perfused livers from pregnant (19-21 days gestation) and nonpregnant female rats. Bile flow, bile acid concentration, bile acid secretory rate, dibromosulfophthalein (DBSP) concentration in bile, and DBSP secretory rates were determined in livers infused continuously with DBSP and initially with SAL (1 ml/hr, 45 min), followed by TC (60 mumol/hr, 1 ml/hr; 75 min) or initially with TC (45 min) followed by SAL (75 min). The order of infusion (SAL-TC vs. TC-SAL) had no significant effect. TC infusion significantly increased all measures in livers from both nonpregnant and pregnant rats. Two-way analysis of variance followed by the Tukey-Kramer test showed that bile flow (microliter/min/g liver) and DBSP concentration in bile (mumol/ml) were significantly decreased during SAL infusions in pregnancy. These two measures plus bile acid and DBSP secretory rates (nmol/min/g liver) were also significantly decreased during TC infusion in pregnancy. Pregnancy had no effect on bile acid concentration in the presence of SAL or TC infusions. When bile flow, bile acid, and DBSP secretory rates were calculated per whole liver, only the DBSP secretory rate was significantly decreased in pregnancy. These data indicate that bile flow and bile acid secretion do not increase in proportion to the increase in liver weight in pregnancy so that these measures are decreased when expressed per g liver. Pregnancy appears to have a real inhibitory effect on DBSP since its secretion is depressed when activity is expressed per g liver or per whole organ.

Animals↗