Changes in transglutaminase activity in carbon tetrachloride-damaged rat liver

Summary A significant decrease in transglutaminase (TGase) activity was observed in the cytosol and nuclear fractions of carbon tetrachloride-damaged rat liver. The degree of decrease in TGase activity in the cytosol fraction was closely related to the serum transaminase level. Gel filtration studies revealed that TGase activity in 80 kDa fractions significantly decreased, but that in 160 kDa fractions slightly increased after carbon tetrachloride treatment.     

Changes in transglutaminase activity in carbon tetrachloride-damaged rat liver.

A significant decrease in transglutaminase (TGase) activity was observed in the cytosol and nuclear fractions of carbon tetrachloride-damaged rat liver. The degree of decrease in TGase activity in the cytosol fraction was closely related to the serum transaminase level. Gel filtration studies revealed that TGase activity in 80 kDa fractions significantly decreased, but that in 160 kDa fractions slightly increased after carbon tetrachloride treatment.     

Demonstration of a receptor for 5 alpha-androstane-3 beta, 17 beta-diol in the cytosol of the anterior pituitary of prepubertal male rats]

The presence of a specific receptor for 5alpha-androstan-3beta, 17beta-diol (3beta-diol) in the pituitary cytosol from prepubertal male rats was demonstrated. Its characteristics were: Ka = 5.2.10(7) M-1 KD = 1.9 X 10(-8) M, number of specific binding = 8.7 10(-14) moles per mg of proteins. Its sedimentation constant was 3 S. Competition assays showed that only 3beta-diol itself and estrogens were able to compete for the binding sites for 3beta-diol. Androgens, including 3alpha-diol, were inefficient. This receptor was found only in pituitary cytosol, it was missing from hypothalamic or cortical cytosols. This special localization seemed to foreshadow a specific role for 3beta-diol in the anterior hypophysis.     

Analysis of nuclear apoptotic process in a cell-free system

We report an analysis of the apoptotic process of mouse liver nuclei induced in a cell-free carrot cytosol system by cytochrome c. Typical characteristics of apoptosis were observed, such as chromatin condensation, margination, apoptotic bodies and DNA ladders. Furthermore, transmission and scanning electron microscope analysis of the apoptotic nuclei detected chromatin-free nuclear vesicles before apoptotic bodies appeared at a comparatively late phase. When AC-YVAD-CHO, an inhibitor of caspase 6, was introduced into the system, these vesicles and apoptotic bodies disappeared completely within our study sections. We confirmed the results using whole-mount electron microscopy, and found that although the nuclear lamina was destroyed early, the nuclear matrix largely remained intact during the course of apoptosis. The nuclear matrix played an important role in maintaining the integrity of apoptotic cells and connecting the apoptotic bodies and apoptotic nucleus. Received 29 September 2000; revised 10 December 2000; accepted 13 December 2000     

High affinity binding of labeled androgens in the androgen-target tissues of the male rhesus monkey

Summary High affinity testosterone (T)-specific and dihydrotestosterone (DHT)-specific binding sites exist in a 12 ratio in the cytosol fractions of the caput epididymidis, prostate, seminal vesicles and the ductus deferens of the rhesus monkey. The number of androgen-binding sites in the caput epididymidis is 3 times greater than that of the other 3 tissues.This investigation was supported by financial assistance from the Indian Council of Medical Research and the University Grants Commission.     

The role of the nuclear envelope in cellular organization

Over the last years it has become evident that the nuclear envelope (NE) is more than a passive membrane barrier that separates the nucleus from the cytoplasm. The NE not only controls the trafficking of macromolecules between the nucleoplasm and the cytosol, but also provides anchoring sites for chromosomes and cytoskeleton to the nuclear periphery. Targeting of chromatin to the NE might actually be part of gene expression regulation in eukaryotes. Mutations in certain NE proteins are associated with a diversity of human diseases, including muscular dystrophy, neuropathy, lipodistrophy, torsion dystonia and the premature aging condition progeria. Despite the importance of the NE for cell division and differentiation, relatively little is known about its biogenesis and its role in human diseases. It is our goal to provide a comprehensive view of the NE and to discuss possible implications of NE-associated changes for gene expression, chromatin organization and signal transduction. Received 8 August 2005; received after revision 13 October 2005; accepted 13 October 2005     

The effect of polysaccharide-protein complex isolated from Candida albicans on regional blood flow in rats.

After i.v. administration to rats of polysaccharide-protein complex, isolated from Candida albicans, a decrease of cardiac output was observed from 20 sec to 240 min postinjection, followed by a recovery at 360 min. Concomitantly the regional blood flow was maintained in heart and lungs, moderately decreased in intestine, liver and adrenals and markedly reduced in skin, muscle, spleen and kidney.     

The effect of polysaccharide-protein complex isolated fromCandida albicans on regional blood flow in rats

Summary After i.v. administration to rats of polysaccharide-protein complex, isolated fromCandida albicans, a decrease of cardiac output was observed from 20 sec to 240 min postinjection, followed by a recovery at 360 min. Concomitantly the regional blood flow was maintained in heart and lungs, moderately decreased in intestine, liver and adrenals and markedly reduced in skin, muscle, spleen and kidney.     

Evidence for synergism in steroid hormone-receptor association.

A number of glucocorticoids stimulated oestradiol binding to liver cytosol receptor; oestradiol activated glucocorticoid receptor association at a time when it reversed triamcinolone mediated increase in liver glycogen synthesis.     

Mitochondrial and cytosolic glutathione after depletion by phorone in isolated hepatocytes

Summary The glutathione content of cytosol and mitochondria of isolated hepatocytes was depleted by addition of a low concentration of phorone (0.5 mM) by 75% and 40% respectively. Different rates of replenishment indicate metabolic separation of cytosolic and mitochondrial glutathione pools. The release from hepatocytes occurred at a rate of about 8 nmol/g wet weight/min, both in controls and after phorone depletion.This work was supported by the Ministerium für Wissenschaft und Forschung. Nordrhein-Westfalen, and by Deutsche Forschungsgemeinschaft.     

Acute changes in dopamine metabolism in the medio-basal hypothalamus following adrenalectomy

During the first hour following adrenalectomy the alpha-MPT-induced disappearance of dopamine was increased in the arcuate nucleus compared to that in sham-operated rats. In a number of other brain regions of both adrenalectomized and sham-adrenalectomized rats only stress-induced changes were observed in catecholamine utilization. These data suggest that corticosterone selectively modulates dopamine utilization in the medio-basal hypothalamus.     

The metabolic fate of [35S]-diallyl disulphide in mice

Summary Diallyl disulphide (DADS) is a major constituent of garlic oil. Uptake of [³⁵S]-labelled diallyl disulphide by mouse liver is highest at 90 min after treatment. 2h after treatment with [³⁵S]-DADS, 70% of the radioactivity is present in the liver cytosol of which 80% is metabolized to sulphate.     

Timing of mitosis in Physarum polycephalum: effects of agents affecting cyclic AMP concentrations.

Cultures of Physarum polycephalum incubated with caffeine or theophylline for over 100 min prior to mitosis exhibited mitotic delay proportional to the time of treatment before 100 min. Starved cultures exhibited mitotic delay at times of starvation longer than 180 min and slight stimulation from 100-180 min. Dibutyryl cAMP appeared to accelerate reconstruction of the nucleus following mitosis.     

Evidence for synergism in steroid hormone-receptor association

Summary A number of glucocorticoids stimulated oestradiol binding to liver cytosol receptor; oestradiol activated glucocorticoid receptor association at a time when it reversed triamcinolone mediated increase in liver glycogen synthesis.These studies were supported by the DRGST (IMB 7570744), the INSERM (CL 7650014) and the CNRS (AI 03 1917).     

Dehydroepiandrosterone sulfate-binding sites in plasma membrane from human uterine cervical fibroblasts.

Dehydroepiandrosterone sulfate (DHA-S) plays a critical role in cervical dilatation at labor. Incubation of cervical fibroblasts with [3H]DHA-S caused a rapid and saturable increase in cellular radioactivity: an apparent equilibrium was reached by 2 min. There was no detectable conversion of DHA-S into DHA or oestradiol. When the fibroblasts loaded with [3H]DHA-S were homogenized and fractionated, the specific radioactivity in the plasma membrane fraction was enriched approximately 8- to 9-fold compared with the whole homogenate; only low amounts of radioactivity were observed in the other subcellular fractions. The binding of DHA-S to plasma membrane preparations showed saturation kinetics with an apparent equilibrium dissociation constant (Kd) of 12 nM, and the binding capacity (Bmax) was calculated to be 1.25 fmol/mg protein. Neither DHA nor oestrone sulfate affected [3H]DHA-S binding to the plasma membrane. The plasma membranes of skin fibroblasts did not show specific binding sites for DHA-S. These findings demonstrate the presence of specific binding sites for DHA-S in the plasma membrane of cervical stroma cells. The fetal adrenal steroid may exert its action on cervical ripening at least in part through membrane-associated binding sites, or receptors.     

Activity of two components of serum ribonuclease under conditions of physical exercise.

Serum ribonuclease activity before and after physical exercise in healthy persons was estimated. It is found that a work load of 6000 kgm/5 min increased ribonuclease activity measured at pH 8.5 and decreased the activity of the same enzyme measured at pH 7.0 in the presence of Zn SO4. The observed changes were more pronounced in untrained than in trained persons.     

CAP2, cyclase-associated protein 2, is a dual compartment protein

Cyclase-associated proteins (CAPs) are evolutionarily conserved proteins with roles in regulating the actin cytoskeleton and in signal transduction. Mammals have two CAP genes encoding the related CAP1 and CAP2. We studied the distribution and subcellular localization of CAP1 and CAP2 using specific antibodies. CAP1 shows a broad tissue distribution, whereas CAP2 is significantly expressed only in brain, heart and skeletal muscle, and skin. CAP2 is found in the nucleus in undifferentiated myoblasts and at the M-line of differentiated myotubes. In PAM212, a mouse keratinocyte cell line, CAP2 is enriched in the nucleus, and sparse in the cytosol. By contrast, CAP1 localizes to the cytoplasm in PAM212 cells. In human skin, CAP2 is present in all living layers of the epidermis localizing to the nuclei and the cell periphery. In in vitro studies, a C-terminal fragment of CAP2 interacts with actin, indicating that CAP2 has the capacity to bind to actin.     

Activity of two components of serum ribonuclease under conditions of physical exercise

Summary Serum ribonuclease activity before and after physical exercise in healthy persons was estimated. It is found that a work load of 6000 kgm/5 min increased ribonuclease activity measured at pH 8.5 and decreased the activity of the same enzyme measured at pH 7.0 in the presence of ZnSO₄. The observed changes were more pronounced in untrained than in trained persons.