Autoimmune-associated lymphoid tyrosine phosphatase is a gain-of-function variant

A SNP in the gene PTPN22 is associated with type 1 diabetes, rheumatoid arthritis, lupus, Graves thyroiditis, Addison disease and other autoimmune disorders. T cells from carriers of the predisposing allele produce less interleukin-2 upon TCR stimulation, and the encoded phosphatase has higher catalytic activity and is a more potent negative regulator of T lymphocyte activation. We conclude that the autoimmune-predisposing allele is a gain-of-function mutant.     

Human recombination hot spots hidden in regions of strong marker association

The fine-scale distribution of meiotic recombination events in the human genome can be inferred from patterns of haplotype diversity in human populations but directly studied only by high-resolution sperm typing. Both approaches indicate that crossovers are heavily clustered into narrow recombination hot spots. But our direct understanding of hot-spot properties and distributions is largely limited to sperm typing in the major histocompatibility complex (MHC). We now describe the analysis of an unremarkable 206-kb region on human chromosome 1, which identified localized regions of linkage disequilibrium breakdown that mark the locations of sperm crossover hot spots. The distribution, intensity and morphology of these hot spots are markedly similar to those in the MHC. But we also accidentally detected additional hot spots in regions of strong association. Coalescent analysis of genotype data detected most of the hot spots but showed significant differences between sperm crossover frequencies and historical recombination rates. This raises the possibility that some hot spots, particularly those in regions of strong association, may have evolved very recently and not left their full imprint on haplotype diversity. These results suggest that hot spots could be very abundant and possibly fluid features of the human genome.     

Testosterone metabolism by mouse placenta in vitro

Zusammenfassung 4-C¹⁴-Testosteron wurde durch Mäuseplazenta in vitro zu Steroiden umgesetzt: 3-Hydroxy-5-androstan-3, 17-dion, 3-Hydroxy-5-androstan-3, 17-dion, 4-Androsten-3, 17-dion und 5-Androstan-3, 17-dion. Eine Umsetzung von Testosteron zu Östrogenen wurde nicht nachgewiesen.     

Stabilization of mouse brain glutamic decarboxylase

Résumé Le GAD du cerveau de souris, une enzyme sensible au SH, peut être purifié en présence de 2-aminoéthyl-isothiouronium-bromide (AET), une substance radioprotective. AET, qui existe en solution neutre, comme 2-mercaptoethyl guanidine, protège les enzymes qui contiennent le SH bien mieux que les quantités isomolares du GSH ou du dithioérythrétol (Cleland's reagent). En outre, il est possible que l'AET soit une source naissante de mercaptoéthylamine qui produit un dérivatif de thiazolidine avec le groupe aldéhyde de pyridoxal phosphate qui opère indépendamment comme galeyeur. Ce mécanisme explique la qualité radioprotective supérieure de l'AET et des aminothiols in vivo en comparaison des substances qui ne contiennent pas d'amino.     

Uptake from blood and conjugation of bilirubin by the intestinal Mucosa of Wistar,Gunn and hepatectomized rats

Resumen Se infundió bilirrubina no conjugada en tres grupos de ratas: normales, totalmente hepatectomizadas y Gunn homocigotas, observándose la aparición de bilirrubina conjugada en la mucosa intestinal de los dos primeros grupos. Dichos experimentos, confirmados con el uso de bilirrubina-¹⁴C, demuestran que la bilirrubina no conjugada sérica puede ser captada y conjugada por la mucosa intestinal de la rata.

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This work was supported in part by a grant from C.O.F.O.I.C., Pcia. de Santa Fe, República Argentina. We thank Mr.J. Rassero for his invaluable technical assistance.     

The heuristic role of mathematics in the initial development of superconductivity theory

During the first twenty-four years after the discovery of superconductivity many attempts to derive an adequate theory failed, mainly because the problem was not formulated quite correctly. In this paper we investigate certain questions related to the heuristic role of mathematics in the appropriate formulation of the problem that had to be solved and the development of a theory which was hindered by theoretical superstitions.     

Determination of the dry mass of nervous and glial cell nuclei by interference microscopy

Riassunto In questo lavoro si descrive una nuova metodica per la determinazione della massa secca dei nuclei delle cellule nervose o gliali mediante il microscopio ad interferenza. Sono riferiti i valori della massa secca, dei volumi e della concentrazione dei nuclei isolati sia da tessuto liofilizzato che da tessuto fresco.

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This investigation was supported by a grant to this Department from the Consiglio Nazionale delle Ricerche (No. 04/76/4/3482).     

A diploid population of the polyploid amphibianOdontophrynus americanus and an artificial intraspecific triploid hybrid

Resumen La ocurrencia de poliploidia ha sido relatada en anuros de la familia Ceratophrydidae incluyendo la especie tetraploideO. americanus (4n=44). En una área geográfica distinta, sin embargo, fue observada una población diploide deO. americanus (2n=22). Fueron obtenidos híbridos intraespecíficos triploides (3n=33) por cruzamiento de ejemplares diploides y tetraploides deO. americanus.