Biomedical subjects
Publications and source records attributed to B Halpern.
Intraperitoneal injection of Corynebacterium parvum (C. parvum) into Balb/c mice produces a protection against toxicity or lethality provoked by ionizing radiation (750 R and 950 R). Survivals reaching nearly 90 days have been recorded.
A quantitative analysis of amino acids in microsamples of dried blood spots by chemical ionization mass spectrometry has been developed. Isotope ratio determination was used as the quantitating technique via multiple labelled internal standards. This procedure yields excellent precision and accuracy as demonstrated by the analysis of known amino acid mixtures and of phenylalanine in the blood from newborns.
The lectin from hemolymph of Limulus polyphemus was purified by affinity chromatography on insolubilized bovine submaxillary mucin. The purity of the protein was checked by crossed immunoelectrophoresis. Agglutination of human red blood cells was completely abolished after neuraminidase treatment, while other cells were still agglutinable after the same treatment but required a higher concentration of lectin. Limulin was able to simulate about 50% of human peripheral lymphocytes. This mitogenic effect could be inhibited by bovine submaxillary mucin but not by the disialylated mucin. Related to the known oligosaccharide-binding specificity of limulin and of the other nonspecific activators of lymphocytes, the authors suggest that lymphocyte stimulation is triggered by binding to a glyco-conjugate bearing the following carbohydrate chains: NANA leads to GalNac leads to or NANA leads to Gal leads to GlcNAc leads to Man.
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Metabolic studies on two patients with defects in the tyrosine oxidation pathway are reported. Serum tyrosine was greatly elevated in both patients (1.37 and 1.52 mmol/liter, respectively) and both excreted large quantities of p-hydroxyphenylacetic acid, p-hydroxyphenyllactic acid, and p-hydroxyphenylpyruvic acid. Deuterated tyrosine loads were administered to both patients, before and after lowering of the serum tyrosine concentration by dietary treatment, and to a normal adult control subject. In one patient the excretion of the deuterated (D2)-tyrosine load was more than 300 times that found in the control subject whether the test was done at high or low serum tyrosine level and the pattern of metabolites indicated a persistent defect in p-hydroxyphenylpyruvic acid oxidase. Enzyme assays on needle liver biopsy supported this finding. In the second patient excretion of the D2 label was 300 times that of the control at high serum tyrosine levels, but only 5 times normal at low serum tyrosine levels. This finding was interpreted as indicating substrate inhibition of p-hydroxyphenylpyruvic acid oxidase. The primary defect has not been established in this patient, but the findings are compatible with a defect in hepatic-soluble tyrosine aminotransferase.
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The effect of Corynebacterium parvum (C. parvuum) on the immune response of the guinea pig to ovalbumin varies with the protocol of immunization. The marked effect of C. parvum on the anamnestic response in the rabbit has been confirmed in the guinea pig when immunization is carried out intradermally with a mixture of C. parvum and ovalbumin. When C. parvum is given intravenously or subcutaneously or intradermally but separately from the antigen, this effect is not observed. Whatever the route of injection guinea pigs treated with C. parvum show skin reactions of delayed type hypersensitivity at the site of an intradermal booster when the latter is given at least 27 days after primary immunization.
After intradermal immunization with a mixture of Corynebacterium parvum (C. parvum) and ovalbumin guinea pigs show a markedly increased anamnestic response to an intradermal booster of ovalbumin as compared to controls treated with ovalbumin only. At the same time a reaction of delayed type hypersensitivity is observed in the treated animals, but not in controls. The enhanced anamnestic response as well as the posivitive skin reaction were transferred to strain 2 histocompatible guinea pigs by peripheral blood leukocytes as well as by peritoneal exudate cells. Passive transfer was not obtained after prior irradiation of donor animals.
Increased chromosomal breakage is observed in NZB mice. Breeding experiments with mice selected according to breakage frequencies provide evidence that the proportion of animals with high and low breakage figures in the first and second generation progeny depends on the phenotype of the parents.
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The identification of a complex ninhydrin positive mixture present in the urine of a child suffering from chronic skin ulceration and oedema by direct chemical ionisation mass spectrometric analysis is described. The compounds were shown to be dipeptides, of which glycylproline was the major constituent. At least 15 dipeptides were identified in the urine, most of which contained proline or hydroxyproline in the carboxy terminal position. The results suggested that the patient suffered from a defect in collagen metabolism. This hypothesis was subsequently confirmed by a grossly diminished level of prolidase in cultured fibroblasts and erythrocytes.
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Treatment of tumour cells with heat ranging between 46 and 52 degrees C attenuates strongly their virulence and renders the tumour cells immunogenic to the host. By repeated administration of heat treated tumour cells suspended in Freund's complete adjuvant, the animals acquire a state of immunity which makes them tolerant to tumour inocula 100% lethal in the controls. The immunity so conferred is cell-mediated and can be adoptively transferred to isogenic recipients with donor peritoneal exudate and, to a lesser degree, splenic cells.
The administration of Corynebacterium parvum (C. parvum) stimulates in the mouse the bone marrow colony forming cell compartment in two stages. The first stage reaches pic values one day after two consecutive injections and the second, more important stage, reaches a pic at the 9th day which lasts over 27 days. There is no evidence that this effect is related to the liberation of CSF.
The amino acid sequence of a polypeptide can be deduced by an identification of all the dipeptides obtained from a Dipeptidylaminopeptidase I hydrolysate of the original polypeptide and its des N-terminal amino acid derivative. The components of such dipeptide mixtures can be readily identified from the chemical ionization (helium) mass spectra of their N-ethoxycarbonylpropenyl methyl ester derivatives without prior separation. The pyrolytic conversion of N-protected peptide dimethyltrideuteromethyl anilinium salts to their methyl esters in the direct insertion probe of a mass spectrometer was found to be most suitable for the derivatization of such dipeptide mixtures.
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Radioactive nuclear DNA from chicken cells was fractionated according to their frequency of reiteration. By hybridization with an excess of purified polysomal mRNA, the proportion of repetitious DNA hybridized, greatly exceeded that of non-repetitious DNA.