Fusion of microsomal vesicles

Summary Studies which indicate the fusion of rat liver microsomal vesicles show that the rate of fusion of microsomal vesicles, as revealed by electron microscopic examinations, is dependent on the fusion temperature and the amount of detergent present in the microsomal suspension.Acknowledgments. We thank Miss R. Kannler for excellent technical assistance. The electron microscopy was performed in Anatomisches Institut and the Strahlenzentrum of the University of Giessen. This investigation was supported by the Deutsche Forschungsgemeinschaft (Schu 54/5) and by the Stiftung Volkswagenwerk (AZ 11 2454).     

Membrane vesicles, current state-of-the-art: emerging role of extracellular vesicles

Release of membrane vesicles, a process conserved?in both?prokaryotes and eukaryotes, represents an evolutionary link, and suggests essential functions of a dynamic extracellular vesicular compartment (including exosomes, microparticles or microvesicles and apoptotic bodies). Compelling evidence supports the significance of this compartment in a broad range of physiological and pathological processes. However, classification of membrane vesicles, protocols of their isolation and detection, molecular details of vesicular release, clearance and biological functions are still under intense investigation. Here, we give a comprehensive overview of extracellular vesicles. After discussing the technical pitfalls and potential artifacts of the rapidly emerging field, we compare results from meta-analyses of published proteomic studies on membrane vesicles. We also summarize clinical implications of membrane vesicles. Lessons from this compartment challenge current paradigms concerning the mechanisms of intercellular communication and immune regulation. Furthermore, its clinical implementation may open new perspectives in translational medicine both in diagnostics and therapy.     

Induction of microsomal drug-metabolizing enzymes caused by hexobarbital

Summary Hexobarbital was given to anaesthetized mice for a period of 7 h by repeated i. p. injection, first of 100 mg/ kg, then several times of 50 mg/kg. A high level of hexobarbital was maintained in the liver. The activity of microsomal drug-metabolizing enzymes was induced by this treatment with hexobarbital. 30 min after a single i. p. injection of 100 mg/kg of hexobarbital, there was a significant inhibition of aminopyrine N-demethylase but none of cytochrome c and neotetrazolium reductases.—Hexobarbital in vitro inhibits aminopyrine N-demethylase but not cytochrome c reductase.     

Occurrence of vesicles in rabbit seminal plasma

Zusammenfassung Es konnte gezeigt werden, dass die 2 schnell sedimentierende Komponenten, isoliert aus Kaninchensamenflüssigkeit von verschiedenen Zonen eines unterbrochenen Sucrosegradienten in elektronenmikroskopischen Aufnahmen vesikuläre Strukturen darstellen. Die langsamer sedimentierende Komponente (85S) hat einen kleineren Durchmesser (507 Å) und ist weniger dicht (1.16 g/cm³) als die schneller sedimentierende Komponente mit einem durchschnittlichen Durchmesser von 609 Å und einer Dichte von 1.20 g/cm³. Die Dekapazitationsaktivität in Samenflüssigkeit kommt beiden zu und nicht nur wie bis jetzt angenommen wurde, der 85S Komponente. Zwei verschiedene Vesikeltypen wurden auch in der Samenflüssigkeit von Mensch und Stier gefunden.     

Induction of microsomal drug-metabolizing enzymes caused by hexobarbital.

Hexobarbital was given to anaesthetized mice for a period of 7 h by repeated i. p. injection, first of 100 mg/kg,then several times of 50 mg/kg. A high level of hexobarbital was maintained in the liver. The activity of microsomal drug-metabolizing enzymes was induced by this treatment with hexobarbital. 30 min after a single i. p. injection of 100 mg/kg of hexobarbital, there was a significant inhibition of aminopyrine N-demethylase but none of cytochrome c and neotetrazolium reductases. Hexobarbital in vitro inhibits aminopyrine N-demethylase but not cytochrome c reductase.     

Dense core vesicles during photoreceptor development

Summary The presence of dense core vesicles in the terminal expansions of photoreceptors in development is decribed in the chick embryo retina, from the 16th to the 18th day of incubation.Acknowledgment. J.M.G.-G. was supported by a grant from the Comision Asesora de Investigacion Cientifica y Tecnica, Madrid, Spain.     

Non-linear kinetics of microsomal styrene monooxygenase after phenobarbital pre-treatment

Summary Pretreatment of rats with phenobarbital, but not with 3-methylcholanthrene, induces liver microsomal styrene monooxygenase. Under these conditions the kinetic profile is not linear and can be divided into 2 distinct curves. Evidence is presented indicating that the combined treatment with phenobarbital and CoCl₂ destroy the high affinity enzyme, suggesting that the native cytochrome is less sensitive to the action of CoCl₂.This paper was supported by grant No. 181-77-ENVI I awarded by EEC.     

Inhibition of liver microsomal epoxide hydrase by cyproheptadine epoxide

Summary Cyproheptadine epoxide is a competitive inhibitor or rat liver microsomal epoxide hydrase with an apparent K₁-value of 0.75 mM. Cyclobenzaprine and its epoxide stimulate in vitro the activity of this enzyme, whereas cyproheptadine, carbamazepine and carbamazepine epoxide have no effect.     

Role of Golgi vesicles in plant cell elongation

Resumen La rápida elongación de las células durante la diferenciación se debe, entre otros motivos, a un incremento de la membrana envolvente; este incremento es originado por el aporte de vesículas del aparato de Golgi cuyas membranas coalecen con el plasmalema y su contenido se deposita externamente junto al material amorfo de la membrana.     

NADPH and ascorbate catalyzed peroxidation of microsomal lipids during ageing

Riassunto La formazione di lipoperossidi nei microsomi di fegato di ratto in presenza di NADPH diminuisce con la senescenza. Il conrtario sembra invece avvenire in presenza di ascorbato. Ciò potrebbe indicare una maggiore suscettibilità delle membrane microsomiali a fenomeni lipoperossidativi aspecifici in tale condizione.