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Biomedical subjects

P Mandel

Publications and source records attributed to P Mandel.

At least 37 records · Page 2Linked to original sources
PubMed1993

Cytoplasmic poly(ADP-ribose)polymerase from mouse plasmacytoma free messenger ribonucleoprotein particles: purification and characterization.

A cytoplasmic poly(ADP-ribose)polymerase (PARP) was purified from mouse plasmacytoma free messenger ribonucleoprotein particles using chromatography on 3-aminobenzamide affigel-10. The purified protein showed one band at 116 kDa on SDS-polyacrylamide gel electrophoresis and shared similar antigenic sites to the nuclear PARP. An apparent Km for NAD of 100.5 +/- 6.3 microM and a Vmax of 174 +/- 40 nmoles of ADP-ribose incorporated/min/mg protein were observed. RNA was detected in the enzyme preparation and the enzymatic activity was not DNA dependent.

Animals↗
PubMed1993

ADP-ribosylation of neurofilaments by a cytoplasmic ADP-ribose transferase associated with free mRNP.

ADP-ribosylation of neurofilaments by an ADP-ribose transferase isolated from cytoplasmic ribonucleoprotein particles is demonstrated. The 150 kDa neurofilament subunit appears to be the main ADP-ribose acceptor with the transfer of ADP-ribose dimers or monomers. A binding of about 1 mole ADP-ribose per 8 moles of neurofilament subunits has been recorded. An interaction between neurofilaments' ADP-ribosylation and their phosphorylation state is demonstrated.

Adenosine Diphosphate Ribose↗
PubMed1993

Cell culture of tumors alters endogenous poly(ADPR)polymerase expression and activity.

Poly(ADP-ribose)polymerase, a chromatin-bound enzyme, actively participates in processes such as cell proliferation, differentiation, and DNA repair and replication. This enzyme is also implicated in cell transformation, and its inhibition has been proposed to potentiate anti-cancer drug activity. Since cells prepared from tumor biopsies and established tumor cell lines are commonly used to evaluate the efficiency of anticancer therapies, we have compared poly(ADP-ribose)polymerase activity in animal tumor cells growing in vivo and in cell culture. Three tumor types were tested: a mastocytoma (P815), a lymphoma (RDM4), and a glioma (C6). Our results show that cell culture alters poly(ADP-ribose)polymerase levels and activity. Endogenous poly(ADP-ribose) activity was several fold higher in exponentially growing cells than in cells freshly recovered from solid or ascitic tumors. Moreover, polymerase activity increased with culture time, reaching a maximum when cells became confluent. Measurements of poly(ADP-ribose)polymerase gene expression and protein amount indicate that lower enzyme activity in tumors grown in vivo are sustained by decreases in poly(ADP-ribose)polymerase mRNA and protein amount. In contrast, the increase in endogenous poly(ADP-ribose)polymerase activity observed in cultured cells was due to enzyme activation and not to de novo protein synthesis. Such differences must be considered when assessing the applicability of cell-culture results to in vivo situations.

Animals↗
PubMed1993

Brain monoamines following castration of aggressive muricidal rats.

The effect of castration on the levels of brain monoamines and their metabolites has been investigated in rats which became or did not become muricidal following long-term isolation. Fourteen brain areas were explored: olfactory bulbs (OB), olfactory tubercles (OT), septum (Se), striatum (Sr), amygdala (A), thalamus (Th), hypothalamus (Hy), hippocampus (Hi), superior colliculus (SC), inferior colliculus (IC), raphe (Ra), pons-medulla (PM), frontal cortex (FC), temporal cortex (TC) and parietal cortex (PC). Except in the raphe of non muricidal rats and in the striatum of muricidal animals, all other areas examined demonstrate some changes of monoamines neurotransmitter or their metabolites after castration. The strongest changes, always increases, were found in the thalamus. In several brain areas, the changes occurring after castration, differ quantitatively and qualitatively in muricidal and non-muricidal rats.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1993

Association of mitochondrial ADP-ribosyl transferase activity with the DNA-protein complex.

The rat liver mitochondrial DNA protein complex was purified employing a linear sucrose gradient. The ADP-ribosyl transferase activity appears to be associated with this protein DNA complex. Predominant acceptor proteins ranged between 116-30 KDa as revealed by LDS gel electrophoresis. These fractions did not contain any significant NAD glycohydrolase activity.

Animals↗
PubMed1993

Alcohol exposure before pregnancy: effect on GABA levels and turnover in rat offspring.

The GABA levels and turnover rates in various brain areas from 2-month-old rats born to mothers who consumed 20% (v/v) alcohol during 1 month only before pregnancy, were investigated. A decreased level was found in the olfactory tubercules and an increase was observed in the hypothalamus. The turnover rates were reduced in both areas, whereas an increase was observed in the frontal cortex. These results indicate that biochemical alterations may occur in the offspring even if the fetus did not develop under alcoholization.

Animals↗
PubMed1992

Poly(ADPR)polymerase expression and activity during proliferation and differentiation of rat astrocyte and neuronal cultures.

Poly(ADPR)polymerase (poly(ADPR)P) mRNA and enzymatic activity levels were investigated in primary cultures of rat astrocytes and neurons in the absence or presence of basic fibroblast growth factor (bFGF) and nerve growth factor (NGF), respectively. In cultured rat astrocytes, a biphasic increase in poly(ADPR)P mRNA, associated with enhanced nuclear poly(ADPR)P enzymatic activity, were observed. The first rise in poly(ADPR)P mRNA and enzymatic activity is at the beginning of cell proliferation and the second with the occurrence of cell differentiation. In the presence of bFGF (5 ng/ml) the mRNA peaks and the differentiation-associated poly(ADPR)P enzymatic activity undergoes a 2-fold increase. In neuronal cultures an initial high level of poly(ADPR)P mRNA is followed by a decrease while differentiation is progressively achieved. A limited increase of poly(ADPR)P activity is observed during this phase. In the presence of NGF (50 ng/ml), similar poly(ADPR)P mRNA expression and enzymatic activity patterns are observed. The results suggest that poly(ADPR)P is involved at the onset of nerve-cell proliferation and differentiation.

Animals↗
PubMed1992

GABAA sodium independent receptor sites in a strain of rats presenting generalized non-convulsive seizures.

The role of gamma-aminobutyric acid (GABA), a major inhibitor neurotransmitter in the central nervous system (CNS), is well established in the genesis and the control of epilepsies. The purpose of this work was to study the binding parameters of the Na(+)-independent GABA receptors in the brain of a strain of rats presenting spontaneous generalized non-convulsive seizures. The high- and low-affinity binding sites were evaluated in cerebral cortex, cerebellum, and hippocampus using [3H]muscimol. No significant modification was observed for the Bmax and the Kd of high-affinity binding sites, although a slight decrease of Bmax was noted in the three brain areas in rats with seizures. Concerning the low-affinity binding sites, significant decreases were observed in the values of Bmax in the cortex, cerebellum, and hippocampus of animals with spontaneous seizures, without modification of Kd values. Such changes could be considered to be involved in some of the physiological and behaviour activities observed in this strain of rats.

Animals↗
PubMed1992

Jung et al. reply.

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Journal Article↗