T helper cell differentiation in immune response

Significant progress has been made in understanding the maturation of antigen-specific CD4+ T helper cell responses. Recent progress centers on the network of cytokines, accessory molecules, and cell types that shapes the differentiation of distinct T helper cell subsets. Use of transgenic and knockout mice and well characterized in vivo models have helped clarify the interdependence or independence of many of these complex factors.     

A reading aid for the visually handicapped

A new reading aid for the visually handicapped is described. It consists of a normal pair of fieldglasses and a mirror system, and can be used either monocularly or binocularly. It features an unusually long working distance of 210 mm, regardless of magnification.     

Activation of hydrochloric acid-CrCl3 · 6H2 solutions with N-alkyfamines

An economical procedure for the reactivation of aged CrCl₃ · 6H₂O solutions is required for the practical operation of Fe-Cr-redox cells. N-alkylamines of the general form (n=0, 1, 2, 3,...) are suited to this application. The best results were achieved with tetraethylene pentamine (n=3). The technique functions without energy addition for a considerable length of time and is easy to manage. The mechanism of the reactivation is discussed.     

Aktivit?t und subcellul?re Verteilung einiger Mitochondrien-Enzyme im Skeletmuskel. II. Ver?nderungen im Rindermuskel post mortem

Zusammenfassung Proben desLongissimus-dorsi-Muskels des Rindes wurden bis zu 15 Tage nach dem. Schlachten bei 4° C gelagert. Die Änderung der extrahierbaren absoluten und spezifischen Aktivität der Mitochondrien-Enzyme Aconitase (AC), Fumarase (FU), Glutamatdehydrogenase (GLDH), Malatdehydrogenase (MDH) and Succinodehydrogenase (SDH) während der Lagerung wurde studiert. Es wurde ferner der Einfluß der Lagerung auf die Aktivität der SDH im nicht zentrifugierten Muskelhomogenat ermittelt. Während die Gesamtaktivität von FU und ACpost mortem abnahm, blieb die Aktivität von SDH und MDH nahezu unverändert. Die extrahierbare GLDH-Aktivität wies im Zustand desRigor mortis ein Minimum auf.Durch Bestimmung der Enzymaktivitäten im Preßsaft des unzerkleinerten Gewebes wurde die Änderung der subcellulären Verteilung der Mitochondrien-Enzymepost mortem verfolgt. AC, MDH und SDH wurden während der Lagerung des Muskelspost mortem nicht aus ihrer Bindung an die Mitochondrien freigesetzt. FU wurde nach Eintritt desRigor mortis in geringem Maße freigesetzt. GLDH trat innerhalb von 24 Stdpost mortem in erheblichem Umfang aus ihrer Bindung an Mitochondrien in das Sarkoplasma über.Die Resultate lassen den Schluß zu, daß die Mitochondrien des Rindermuskels im Verlauf desRigor mortis eine Schädigung erfahren, die zu einem partiellen Austritt der Matrix in das Sarkoplasma ohne wesentliche Desintegration der Mitochondrienmembranen führt. Die Möglichkeit einer Öffnung der intramitochondrialen Räume durch Quellung der Mitochondrien als Folge des glykolytisch bedingten pH-Abfalls wird diskutiert.

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Activity and subcellular distribution of some mitochondria) enzymes in skeletal muscle. II. Post-mortem changes in bovine muscle

Summary Samples of bovineM. longissimus dorsi were stored for up to 15 days post mortemat at 4° C. The changes in the extractable absolute and specific activities of the mitochondria) enzymes aconitase (AC), fumarase (FU), glutamic dehydrogenase (GLDH), malate dehydrogenase (MDH) and succinic dehydrogenase (SDH) were determined. The influence of storage on the activity of SDH in the muscle homogenate was also studied. There was a decrease in the total activity of AC and FU post mortem, but no remarkable changes in the activity of SDH and MDH. The GLDH activity showed a minimum at the time of rigor mortis.The changes in the subcellular distribution of the mitochondria) enzymes post mortem were determined by studying the enzyme activities in the press juice of the intact muscle tissue. AC, MDH and SDH were not released from mitochondria) structures during storage of muscle. There was a small release of FU after development of rigor mortis. However, a great part of GLDH was released from the mitochondria into the sarcoplasma within 24 h post mortem.The results show that the mitochondria of bovine muscle undergo a certain damage during development of rigor mortis which results in a partial efflux of the mitochondria) matrix into the sarcoplasma without a remarkable desintegration of the mitochondria) membranes. The possibility of an opening of the intramitochondrial spaces by swelling of mitochondria caused by the decrease of pH post mortem is discussed.

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Stipendiat der Alexander-von-Humboldt-Stiftung. Jetzige Adresse: University of Assiut, Faculty of Agriculture, Assiut, VAR.