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M B Rittenberg

Publications and source records attributed to M B Rittenberg.

At least 91 records · Page 5Linked to original sources
PubMed1975

The immunological properties of pyruvate kinase. II. The relationship of the human erythrocyte isozyme to the human liver isozymes.

We have examined the hypothesis that the human erythrocyte isozyme of pyruvate kinase (EC 2.7.1.40) is a hybrid of the two isozymes present in liver. Rabbit antiserum against purified human erythrocyte pyruvate kinase inactivates the erythrocyte isozyme and the major liver isozyme from human tissue but does not inactivate the minor liver isozyme. The electrophoretic mobilities of the erythrocyte and major liver isozymes are altered by anti-erythrocyte enzyme antibody while the mobility of the minor liver isozyme is unaffected. Gel diffusion analysis indicates cross-reactivity between the erythrocyte and major liver isozyme but no cross-reactivity with the minor liver isozyme. The hybrid hypothesis would predict cross-reactivity including changes in activity and mobility of all isozymes and we conclude, therefore that the hypothesis is incorrect.

Animals↗
PubMed1975

Canine erythrocyte pyruvate kinase. I. Properties of the normal enzyme.

We have compared the kinetic, immunological, and electrophoretic properties of human and canine erythrocyte pyruvate kinase. Both enzymes are allosteric and subject to positive and negative regulation. The allosteric properties of the canine enzyme are more pronounced than those of the human enzyme; however, the properties of both enzymes are consistent with a regulatory function in the glycolytic pathway of their respective erythrocytes. Antiserum against the human enzyme gives precipitin lines of partial identity between the human and canine enzymes on immunodiffusion. The anti-human serum inactivates the enzymatic activity of both enzymes, although it is more effective against the human enzyme than the canine. The two enzymes have slightly different mobilities on starch gel electrophoresis. While we have demonstrated differences between erythrocyte pyruvate kinase from dogs and that from humans, we conclude that the enzymes are sufficiently similar in properties and function to allow use of the dog as a model for human erythrocyte pyruvate kinase deficiency.

Adenosine Diphosphate↗
PubMed1975

Canine erythrocyte pyruvate kinase. II. Properties of abnormal enzyme associated with hemolytic anemia in the Basenji dog.

We have compared the solubility, kinetic, immunological, and electrophoretic properties of erythrocyte pyruvate kinase from normal dogs and Basenji dogs with congenital hemolytic anemia due to pyruvate kinase deficiency. Differences can be detected between the two enzymes by all methods. The enzyme from the affected animals has a greater solubility in ammonium sulfate. It has a lower Km for phosphoenolpyruvate, while the Km for ADP is increased. This enzyme is not inhibited by ATP or activated by fructose 1,6-diphosphate. The enzyme from the affected animals has none of the allosteric properties characteristic of the normal canine enzyme. No difference can be detected by enzyme inactivation with rabbit antiserum against human erythrocyte enzyme, but a slight spur is observed on comparison of the two enzymes by Ouchterlony immunodiffusion. The enzymes also differ in their electrophoretic mobilities on starch gel electrophoresis.

Adenosine Diphosphate↗
PubMed1975

In vitro immunogenicity of trinitrophenylated bacteriophage T4. I. Lack of helper cell cooperation.

A primary immune response was obtained in vitro to trinitrophenylated bacteriophate T4 (TNP-T4) by using normal BALB/c spleen cells challenged in vitro. The primary response was limited to anti-TNP; we failed to find evidence of a primary anti-T4 response in spleen cell cultures challenged with either TNP-T4 or native T4. In vivo priming with the carrier T4 failed to enhance the subsequent in vitro response to TNP-T4 although such priming sometimes caused suppression of the anti-hapten response. The addition of excess free carrier to spleen cell cultures challenged with TNP-T4 failed to suppress the anti-tnp response. Spleen cells treated with anti-theta plus complement were unaffected in their ability to respond to TNP-T4. We conclude that TNP-T4 should be classified among the thymus independent antigens.

Animals↗
PubMed1974

Selective toxicity of diphtheria toxin for malignant cells.

Purified diphtheria toxin is shown to inhibit protein synthesis in Ehrlich-Lettré ascites carcinoma cells in vitro. Protein synthesis in Ehrlich-Lettré cells is at least 10,000 times more sensitive to toxin than protein synthesis in normal mouse spleen or thymus cells. This sensitivity correlates with the observation that Ehrlich-Lettré tumors regress in mice injected with diphtheria toxin but not diphtheria toxoid. Using the criterion of inhibition of protein synthesis in vitro, we show that other mouse malignancies (lymphoma and myeloma) are also more sensitive to diphtheria toxin than normal spleen or thymus. Metastatic human breast carcinoma cells from two individuals, cells from two melanoma nodules removed at different times from a third patient, and cells from melanoma nodules from three additional individuals are shown to be more sensitive to diphtheria toxin than some normal human cells. The toxin sensitivity of protein synthesis in some of the malignant cells tested was so much greater than that of normal cells, that we have proposed that diphtheria toxin should be studied further since it might prove a useful anti-cancer agent in patients whose tumors are first shown to be highly sensitive to toxin in vitro.

Animals↗
PubMed1970

In vitro-initiated secondary anti-hapten response. II. Increasing cell avidity for antigen.

Decreasing antigen in vivo may preferentially stimulate cells with the potential for synthesis of high-affinity antibody through activation of surface receptors with similarly high affinity. This selection should result in cells with increased sensitivity to lower antigen concentrations, cells with greater avidity for antigen. We have followed the in vivo changes in anti-TNP memory-cell sensitivity by initiating the secondary anti-hapten response in vitro. This response was determined by anti-TNP plaque assay. The results indicate that cell populations with increased sensitivity for antigen continue to emerge with time after priming and that this sensitivity may increase 1000-fold in a 4 month period. Increased sensitivity to stimulation by antigen is concomitant with suppression by higher, previously stimulatory doses as in high zone immune tolerance. The data support the hypothesis that memory cells of high avidity result from the selective pressure of diminishing in vivo antigen concentration.

Amino Acids↗
PubMed1968

Heterologous carriers in the anamnestic antihapten response.

Anamnestic antihapten responses were obtained to trinitrophenyl (TNP) when rabbits sensitized to trinitrophenyl-hemocyanin (TNP-KLH) were challenged with TNP-heterologous protein conjugates. Hapten-heterologous carrier conjugates elicited antihapten titers similar in magnitude to those elicited by the homologous carrier conjugate. Hapten-heterologous carrier recall of antihapten was successful as early as 37 days and as late as 11 months after sensitization. There was no correlation between anti-TNP-precipitating antibody titer after sensitization and the ability to respond to challenge by hapten-heterologous carrier. The results are discussed in terms of immunogenicity of sensitization, suppressive effects of persisting postsensitization antibody, and submolecular haptenic environment as factors possibly affecting the heterologous recall process.

Animals↗