5'-Nucleotidase activity in liver homogenates of rats treated with CCl4, colchicine, cycloheximide, emetine, ethanol, ethionine and 5-fluorotryptophan

5'-Nucleotidase activity an enzyme marker of the plasma membranes, increases in female rat liver homogenates following ethionine administration, while homogenates from males show no changes. Treatment with CCl4, colchicine, cycloheximide, emetine, ethanol and 5-fluorotryptophan does not significantly modify the 5'-nucleotidase activity of liver homogenates of either female or male rats.     

On the inhibitory action of endosperm on germination ofCercis siliquastrum seeds

Summary The endosperm inhibits the growth of embryos isolated fromCercis siliquastrum seeds. The inhibitory activity is present in autoclaved homogenates as well as in homogenates remaining after an extraction with chloroform or isobutanol.Acknowledgment. The authors wish to thank Prof. E. Marré, Milan University, for his help in preparation of this paper.     

5′-Nucleotidase activity in liver homogenates of rats treated with CCl4, colchicine,cycloheximide, emetine,ethanol, ethionine and 5-fluorotryptophan

Summary 5-Nucleotidase activity, an enzyme marker of the plasma membranes, increases in female rat liver homogenates following ethionine administration, while homogenates from males show no changes. Treatment with CCl₄, colchicine, cycloheximide, emetine, ethanol and 5-fluorotryptophan does not significantly modify the 5-nucleotidase activity of liver homogenates of either female or male rats.     

The concentration of high molecular weight kininogen antigen in homogenates of various human tissues

Summary The concentration of high molecular weight kininogen, measured in human tissue homogenates, was 2–3 times higher in kidneys, adrenals and thyroid than in homogenates of lung, heart, liver and spleen. No measurable quantities of this protein were found in homogenates of brain and skeletal muscles.This work was supported by a grant from the Department of Medical Sciences of Polish Academy of Sciences.     

Effect of vasectomy on hepatic drug metabolism

2 months after bilateral vasectomy the metabolism of aniline but not aminopyrine was increased in rat liver homogenates, whereas vasectomy did not affect the metabolism of either compound in guinea-pig liver homogenates.     

Effect of vasectomy on hepatic drug metabolism

Summary 2 months after bilateral vasectomy the metabolism of aniline but not aminopyrine was increased in rat liver homogenates, whereas vasectomy did not affect the metabolism of either compound in guinea-pig liver homogenates.Supported by a grant from the University of Nebraska Medical Center.     

Effects of centrophenoxine,piracetam and hydergine on rat brain lipid peroxidation

Summary The cerebral insufficiency improvers centrophenoxine, piracetam and hydergine were tested for their effect on lipid peroxidation of rat brain homogenates, both in vitro and in vivo. There was no effect either in vitro or after chronic 8 week dosing of animals.     

The effect of bisphosphonates on glycolysis in cultured calvaria cells and their homogenate

Rat calvaria cells previously cultured for 7 days in the presence of 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) or dichloromethylenebisphosphonate (Cl2MBP), showed a decrease in the glycolytic pathway. When glycolysis was analyzed under anaerobic conditions, this effect was not observed. The inhibition by the bisphosphonates occurred to a similar degree regardless of whether lactate production was measured in whole cells or in cell homogenates. Bisphosphonates added directly to the homogenate had no inhibitory effect. Thus, the effect is not a direct one and is unlikely to be due to a soluble mediator in the cytoplasm.     

A newly designed decantation for purified synaptic vesicle

Summary A new decanting device of fine stainless steel needles has been developed, which can remove a layer from a gradient with little contamination from the adjacent upper or lower layers. This new apparatus can be used for removal of a very narrow band from a density gradient and has been successfully used in the fractionation of synaptic vesicles from brain homogenates.     

In vitro inactivation of gonadotropin receptors, a membrane-associated action?

Under in vitro conditions the time-dependent inactivation process of LH/HCG receptors is nearly identical in ovarian and testicular homogenates but different in gonadal membrane preparations. In the ovarian membranes the loss of binding sites during the first preincubation time is faster than in testicular membranes, especially in membranes of luteinized rat ovaries. Compared with the homogenates, however, the receptor-inactivation in the membranes is generally delayed. The inhibitory effect of metabolic agents on receptor inactivation indicates that membrane-associated actions are involved in this process.     

Mitochondrien und Citrullinsynthese in der Leber

Summary By differential centrifugation of rat-liver homogenates prepared in isotonic solutions of mannitol it is possible to obtain mitochondria in suspensions that are apparently free from other cellular components. Our preparation contains all of the enzymes responsible for the conversion of ornithine to citrulline with glutamic acid and ammonium or glutamine. The synthesis is strongly inhibited by Janus green, which is a specific vital stain for mitochondria.     

Hydrogen peroxide generation in Trypanosoma cruzi.

Homogenates from T. cruzi epimastigotes produced 3.4 pmoles H2O2/min 10(6) cells, as detected by the cytochrome c peroxidase assay. Addition of NADH or NADPH increased H2O2 production by a factor of 3 and 5, respectively. When supplemented with NADH and NADPH, the mitochondrial, microsomal and supernatant fractions produced H2O2, the soluble fraction and the mitochondrial membranes being apparently the main generators of H2O2. The epimastigote homogenates showed cyanide-sensitive superoxide dismutase activity, equivalent to 0.28 microgram bovine superoxide dismutase per mg homogenate protein.     

Effects of penfluridol on dopamine-sensitive adenylate cyclase in corpus striatum and substantia nigra of rats

Summary Penfluridol, a neuroleptic with diphenylbutyl piperidine structure, blocked the dopamine-sensitive adenylate cyclase in homogenates of corpus striatum and substantia nigra of rats, probably by a competitive antagonism versus dopamine.Acknowledgment. We thank Dr P. Janssen (Beerse, Belgium) for a generous gift of penfluridol.     

Effects of progesterone and estradiol benzoate on superoxide dismutase activity in the brain of male rats

The activities of mitochondrial, manganese-containing superoxide dismutase (MnSOD) and cytoplasmic, copper-zinc-containing superoxide dismutase (CuZnSOD) were measured in subcellular fractions of whole brain homogenates prepared from intact and gonadectomized (GDX) male rats, untreated or treated subcutaneously (sc) with a single dose of 2 mg progesterone (P) and/or 5 g estradiol benzoate (EB). Neither MnSOD nor CuZnSOD was affected by the removal of the testes. Similarly, CuZnSOD activity was steady following systemic administration of P and/or EB to intact and GDX animals 2 h or 24 h prior to sacrifice. On the other hand, both P and EB suppressed MnSOD in the brain of either intact or GDX rats. These results suggest involvement of P and EB in the control of MnSOD activity in the brain of male rats.     

Testosterone metabolism by homogenates of human and rat placenta

Résumé Presque toute la testosterone a été métabolisée dans les incubations avec les homogenates du placenta humain à terme que le cofactor NADPH y ait été ajouté ou non. Mais, les échantillons humains d'une grossesse moins de 24 semaines et aussi les homogenates placentaires du rat à terme et prématuré étaient tous moins actifs dans ce respect.     

In vitro inactivation of gonadotropin receptors,a membrane-associated action?

Summary Under in vitro conditions the time-dependent inactivation process of LH/HCG receptors is nearly identical in ovarian and testicular homogenates but different in gonadal membrane preparations. In the ovarian membranes the loss of binding sites during the first preincubation time is faster than in testicular membranes, especially in membranes of luteinized rat ovaries. Compared with the homogenates, however, the receptor-inactivation in the membranes is generally delayed. The inhibitory effect of metabolic agents on receptor inactivation indicates that membrane-associated actions are involved in this process.This work was supported in part by the Deutsche Forschungsgemeinschaft (Si 185/2). We thank Mrs Rita Rudolph for skilful technical assistance.     

Ox-spleen erythropoietic factor: Chromatographic investigations and dosages

Summary The constant proteic fraction, obtained from ox-spleen homogenates by chromatographic elutions, is the main seat of erythropoietic activity in our assay with polycythemic mice.     

Effects of penfluridol of dopamine-sensitive adenylate cyclase in corpus striatum and substantia nigra of rats.

Penfluridol, a neuroleptic with diphenylbutyl piperidine structure, blocked the dopamine-sensitive adenylate cyclase in homogenates of corpus striatum and substantia nigra of rats, probably by a competitive antagonism versus dopamine.     

Glutamine synthetase activity during mouse brain development

The specific activity of glutamine synthetase (GS) in mouse brain was 2-fold higher in the olfactory bulbs than in other regions. After birth, the specific activity of GS increased more rapidly in medulla oblongata and in olfactory bulbs, than in cerebral and cerebellar cortex. The activity of GS in primary cultures of brain hemispheres increased more slowly than in homogenates of whole brains. However, when astroblasts were treated in vitro with glucocorticoids or mouse brain extracts, GS activity reached 4 times the level measured in the homogenate of an adult mouse brain. We conclude that levels of GS activity may relate to the maturation of astrocytes, and propose that GS may be used as a marker of astrocytic maturation.     

Glutamine synthetase activity during mouse brain development

Summary The specific activity of glutamine synthetase (GS) in mouse brain was 2-fold higher in the olfactory bulbs than in other regions. After birth, the specific activity of GS increased more rapidly in medulla oblongata and in olfactory bulbs, than in cerebral and cerebellar cortex. The activity of GS in primary cultures of brain hemispheres increased more slowly than in homogenates of whole brains. However, when astroblasts were treated in vitro with glucocorticoids or mouse brain extracts, GS activity reached 4 times the level measured in the homogenate of an adult mouse brain. We conclude that levels of GS activity may relate to the maturation of astrocytes, and propose that GS may be used as a marker of astrocytic maturation.