A.T.P. et extractibilité des myosines

Summary A.T.P. has no influence upon the solubility of the myosins, but it hastens the dissociation of the myosin complexes inside of the myofibrils.The decrease in solubility of the myosins in stimulated muscles cannot be explained by a lack of A.T.P., for the addition of A.T.P. (0.3%) to the extract does not change the amount of myosin which goes into solution.     

T. C. Chamberlin,Climate Change,and Cosmogony

This paper examines the life and work of T. C. Chamberlin, a prominent glacial geologist who developed an interest in interdisciplinary earth science. His work on the geological agency of the atmosphere informed his understanding of climate change and other terrestrial phenomena and led him to propose a new theory of the formation of the Earth and the solar system.Chamberlin's graduate seminar at the University of Chicago in 1896 contained all the themes that informed his research programme over the next three decades. These included the carbon dioxide theory of climate change in its relationship to diastrophism and oceanic circulation, the role of water vapour feedbacks in the climate system, and the relationship between multiple glaciations, the climate system, and the formation of the planet.     

Perforin and its role in T lymphocyte-mediated cytolysis.

The killing mediated by cytotoxic T lymphocytes (CTL) represents an important mechanism in the immune defence against tumors and virus infections. The lytic mechanism has been proposed to consist of a polarized secretion of granule-stored molecules, occurring on effector-target cell contact. By electron microscopy, membrane deposited, pore-like lesions are detected on the target cell membrane during cytolysis by CTL. These structures resembled strikingly pores formed during complement attack. Granules of CTL isolated by nitrogen cavitation and Percoll gradient centrifugation were shown to retain cytotoxic activity. Further purification of proteins stored in these granules led to the discovery of a membranolytic protein named perforin which was capable of polymerizing into pore-like structures. In addition to this cytolytic protein, a set of serine esterases was found as well as lysosomal enzymes and proteoglycans, whose function are not yet clearly defined. The role of perforin in the cytotoxic process is currently being explored by ablating the active gene in mice.     

Temperature and acidity for maximal fluorescence of serotonin and serotonin-O.P.T.

Résumé Dans la détermination fluorimétrique de la sérotonine elle-mÊme et du complexe sérotonine-O.P.T. (o-phthaldialdéhyde) un maximum de fluorescence a été atteint pour des normalités de HCl de 3.25–3.50 et 6.25–6.50, respectivement. Pour les deux procédés, on a noté des rapports en sens inverse entre la fluorescence produite et la température de l'échantillon, pour des températures comprises entre 5 à 35 C. Entre la température ambiante (de 20 C) et 5 C, la fluorescence s'est accrue de 30% environ.     

Changes in the T4/T3 molar ratio following thyrotropin releasing hormone injection in cattle.

The injection of thyrotropin releasing hormone into cattle resulted in a rapid decrease in the T4/T3 molar ratio. 2 breeds of cattle, Shorthorn and Africander Cross were studied. The decrease in the T4/T3 molar ratio was significantly greater in the Shorthorn breed. It is concluded that acute stimulation of the thyroid gland with TRH results in enhanced release of both T3 and T4 and that T3 is discharged more rapidly than T4.     

W. T. Astbury,Rosie Franklin,and DNA: A memoir

Astbury's role in the X-ray study of DNA; his failure to continue his pioneering appraisal; surprising details of his MRC grant application; and his disinterest in Beighton's DNA photographs demand attention. Rosie Franklin's later involvement and behaviour receive comments, which, as with Astbury, are based on personal knowledge.     

Optimal Aminco-Bowman spectrophotofluorometer slit sizes and arrangements for the analysis of serotonin-O.P.T.

Résumé Une sélection des dimensions et des arrangements optimaux des fentes a été étudiée pour l'évaluation du complexe sérotonine-O.P.T. (o-phthaldialdéhyde) au moyen du spectrophotofluorimètre Aminco-Bowman. Les meilleures conditions ont été réalisées avec les dimensions de 5.0, 4.0, 5.0, 5.0, 4.0, 5.0 et 5.0 mm dans les positions 1–7 respectivement.     

Use ofEscherichia coli A.T.C.C. 9637 for the asymmetric hydrolysis of amino acid derivatives

Riassunto L'azione delle acilasi presenti nelle cellule diE. coli A.T.C.C. 9637 è stata studiata utilizzando diversi substrati. Si è così trovato che alcuni cloroacetil e fenilacetil amino acidi subiscono un'idrolisi asimmetrica.     

Alteration of early T lymphocyte count in patients with herpes genitalis.

Peripheral blood samples from 52 women, including 16 with herpes genitalis and 36 healthy persons, were studied to enumerate subpopulations of lymphocytes. It was found that the mean percentage of 'active' T lymphocytes was significantly less in the patients with herpes genitalis than in the controls.     

Comparative studies on the trichomonacidal activity of 5-nitroimidazole-derivatives in mice infected s.c. or intravaginally with T. vaginalis.

The trichomonacidal efficacy of metronidazole, tinidazole, nimorazole and ornidazole was studied in mice infected s.c., or for comparison purposes intravaginally. In both test systems, the drugs revealed nearly the same order of efficacy, whereby the compounds showed a marked decrease of activity when analyzed in s.c. infected mice.     

Memory T lymphocytes

Immunological memory protects organisms from recurrent challenge by pathogens. The persistence of a heightened reactive state initiated by antigenic challenge is mediated by long-lived memory lymphocytes. The survival of memory T cells is thought to require stimulation through the T cell receptor (TCR), sometimes by persistent antigen. However, memory T cells can survive in the absence of antigen, in which case TCR stimulation provided by cell surface self-peptide/ major histocompatibility complex (MHC) molecules and cytokines are required to sustain memory T cells. Recent work using mouse models has provided insights into the origin of memory T cells. Understanding the mechanisms that underlie the differentiation and persistence of memory T cells may improve the effectiveness of vaccines through the induction of T cell memory.     

Meccanismo dell'azione attivatrice esplicata dal Guanosintrifosfato (G.T.P.) sui sistemi enzimatici ossidasici dei grassi. Nota IV

Résumé Dans le foie de cobaye l'arseniate ne modifie pas l'activation provoquée par le G. T. P. sur le système enzymatique des acides gras. De ces résultats on peut conclure que le G. T. P. donne directement l'énergie pour la synth`ese des acyl-CoA.