Aryl sulphatase activity inSalmonella typhosa

Zusammenfassung Es wurde die « Aryl Sulphatase »-Aktivität verschiedener Stämme vonSalmonella typhi geprüft. Als Substrat wurde « K-2-hydroxy-5-nitro-phenyl-sulphate » verwendet.ViI, Ty2 und O-901 waren wirksam, wobei ViI die höchste Aktivität zeigte. Nach der Mäuse-Passage verloren die Stämme ViI und Ty2 ihre Aktivität.     

Hormonal induction of steroid sulphatase in the mouse

Summary By comparing steroid sulphatase levels per se, and also ratios to -galactosidase, in 6 sets of mice — normal females, entire and castrated males both with and without exogenous testosterone administration — we obtained support for the contention that induction of this enzyme is in part controlled by male hormones.     

Hormonal induction of steroid sulphatase in the mouse

By comparing steroid sulphatase levels per se, and also ratios to alpha-galactosidase, in 6 sets of mice - normal females, entire and castrated males both with and without exogenous testosterone administration - we obtained support for the contention that induction of this enzyme is in part controlled by male hormones.     

A model of enzymatic kinetics]

In this Note, we study a system of differential equations representing the kinetics of an enzymatic reaction. For a closed system, and in the domain where it has a biological significance, it is shown that: (i) there exists a unique equilibrium point, which is an asymptotically stable point; (ii) if several enzymes act on the same substrates, the equilibrium values of the substrates concentrations take their values within the range of the equilibrium values achieved with each of these enzymes, (iii) the kinetics of the reaction can be approached by a single first-order differential equation, which may be seen as a generalization of the Michaelis equation.     

The kinetics of estrogen binding to rat alpha-fetoprotein

Fluid obtained from rat fetuses was utilized to characterize the affinity, number of binding sites, and the association and dissociation rate kinetics of the binding of estradiol and estrone to AFP. Statistical analysis demonstrated no differences when the values for the AFP-estradiol interaction were compared with those obtained for the ATP-estrone interaction. These data demonstrate that rat AFP specifically binds estradiol and estrone with a high capacity, high affinity, and similar binding kinetics.     

The kinetics of estrogen binding to rat α-fetoprotein

Summary Fluid obtained from rat fetuses was utilized to characterize the affinity, number of binding sites, and the association and dissociation rate kinetics of the binding of estradiol and estrone to AFP. Statistical analysis demonstrated no differences when the values for the AFP-estradiol interaction were compared with those obtained for the AFP-estrone interaction. These data demonstrate that rat AFP specifically binds estradiol and estrone with a high capacity, high affinity, and similar binding kinetics.This work was supported by NSF grant PCM-8109847 and by a Grant-in-Aid of Research from Sigma Xi, The Scientific Research Society.     

The kinetics of cerebral RNA synthesis in relation to the route of injection

Zusammenfassung Nachweis, dass die RNS-Synthese im Gehirn sich nach der Art der Injektion der radioaktiven Substanz richtet, während die Umsatzgeschwindigkeit von³H-Uridin in nicht-nukleotiden Substanzen ebenfalls von der Injektionsmethode abhängig ist.     

Red cell agglutination kinetics: A method for automatic recording with the fragiligraph

Résumé Une méthode est décrite qui permet de mesurer et d'enregistrer automatiquement la vitesse d'agglutination des globules rouges par les hémagglutinines virales, la poly-l-lysine et les antisérums. Le fragiligraphe modèle D2 muni d'un nouvel accessoire a été utilisé. La différence de vitesse d'agglutination entre cellules jeunes et agées a été enregistrée.     

Cell kinetics and radiation pathology

Conclusion Radiation pathology is a general term describing the damage that occurs in tissues after irradiation. After the very low doses, received by the normal working population, no major pathology is seen. There is a hazard of cancer induction if DNA damage that has been inflicted in an individual cell is repaired in such a way that the DNA remains intact but rearranged. This radiation carcinogenesis is however a low risk compared with many chemical carcinogens in the environment and in cancer chemotherapy.The treatment of cancer by radiation is now commonly accepted as one of the most effective forms of treatment. It can kill tumour cells effectively, but the dose that can be given is limited by the normal tissues that are inevitably included in the beam. Cell function is maintained for some time even after very large doses. However normal tissues show a loss of function and structure because the proliferating subcompartment of each tissue is depleted as the radiation injured cells fail to divide and die. The time at which the cell deficit is detected varies from hours in some tissues to months or years in others. It depends upon the normal rate of cell turnover. The apparent sensitivity of each tissue therefore depends upon the time at which the assessment is made. Lung and kidney would appear very resistant at 1–3 months post irradiation, but would seem very radiosensitive at 6–12 months as their latent damage is expressed.The ultimate expression of radiation pathology is the death of the whole animal as the essential organ function fails. The time of this death is only comprehensible if the time sequence and the proliferation kinetics of the target cells are taken into account. It must be recognised that it is initial damage to the clonogenic cells, not to the differentiated cells per se that is important.     

The effect of ligand on the kinetics of the sulfhydryl groups of human hemoglobin with p-mercuribenzoate

The rate of reaction of PMB with the masked sulfhydryls of human hemoglobin derivatives correlates well with the extent of dissociation for various ligands. It is suggested that the alpha1beta2 dimer of hemoglobin participates in the slow step of the reaction with PMB.     

Size of inoculum and growth kinetics of moulds

Zusammenfassung Wachstumsstimulierende Substanzen werden in Kulturen vonAspergillus oryzae gebildet und ins Substrat ausgeschieden. Wenn diese Substanzen während frühen Stadien der Kulturentwicklung einwirken, steigern sie Wachstumsgeschwindigkeit und maximalen Ertrag beträchtlich. Dieses Verhalten erklärt teilweise die bei verschiedenen Schimmelpilzen festgestellte erhöhte Wachstumsgeschwindigkeit und maximale Ausbeute an Mycel durch grössere Impfmengen, da hierdurch eine gewisse kritische Konzentration der betreffenden Substanzen früher erreicht wird als mit kleineren Impfmengen.     

The effect of radiothyroidectomy on blood volume,red cell survival and iron kinetics in puppies

Resumen Cachorros radioyodotiroidectomizados a las 3 semanas de vida mostraron un descenso del 32% en la concentración de hemoglobina y el valor hematocrito. El volumen de la masa roja circulante disminuyó un 27% y el volumen plasmático mostró un aumento del 33%. La sobrevida de los eritrocitos no fue afectada por la tiroidectomia. La magnitud de síntesis hemoglobinica disminuyó en un 45%. Estos resultados indican 1) que la influencia de la tiroidectomía sobre el sistema eritropoyético es independiente del período de la vida en que se la realiza, y 2) que la anemia post-tiroidectomía puede ubicarse entre las anemias no proliferativas, siendo su causa probablemente un descenso de la estimulación eritropoyética.

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Member of the Carrera del Investigador Científico del Consejo Nacional de Investigaciones Cientificas y Técnicas de la RepÚblica Argentina.