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Biomedical subjects

J Molnár

Publications and source records attributed to J Molnár.

At least 127 records · Page 7Linked to original sources
PubMed1982

Ultraviolet light-induced crosslinking of HnRNA to informofer proteins in vitro.

RNA-protein interaction in the 30S subunits of rat liver hnRNP has been studied by crosslinking of informofer proteins to hnRNA induced by UV irradiation. Irradiation of 30S particles with 254 nm UV light in doses of 1 1 x 10(5) erg/mm2 leads to the extensive crosslinking hnRNA to informofer proteins. The crosslinked material was analyzed either by resedimentation in a 15-30% sucrose gradient in the presence of 3 M guanidine-HCl and 1 M NaCl or by centrifugation in a Cs2SO4 density gradient containing guanidine-HCl and sarkosyl. The crosslinked complexes sedimented at about 25S in the sucrose gradient and proved to be heterogeneous in isopycnic centrifugation experiments. The proteins of the crosslinked complexes were analyzed by polyacrylamide gel electrophoresis. Proteins with Mr values of 70 000, 58 000, 43 000 and 40 000 appeared to be crosslinked with hnRNAs of the 30S particles. In the unirradiated 30S particles after centrifugation in the CS2SO4 density gradient containing guanidine-HCl and sarkosyl two minor proteins were observed with Mr values of 70 000 and 58 000, banded in density zones characteristic for free RNA.

Animals↗
PubMed1982

On the origin of luteinizing hormone releasing hormone and somatostatin in the median eminence of the rat hypothalamus.

Luteinizing hormone releasing hormone (LHRH) and somatostatin content of the two halves of the median eminence of the rat hypothalamus were determined by radioimmunoassay three weeks after following deafferentations: (1) unilateral knife cut in front of, laterally and above the preoptic area (preoptic deafferentation); (2) unilateral arched cut at the midlevel of the suprachiasmatic region (suprachiasmatic deafferentation); (3) unilateral arched cut behind the optic chiasm (retrochiasmatic deafferentation); (4) cutting around the medial basal hypothalamus on one side starting with the cut at the posterior level of the optic chiasm (complete deafferentation). Preoptic deafferentation caused a more than 50% decrease in the LHRH content of the ipsilateral half of the median eminence. The reduction in LHRH was even greater (about 70%) in rats with suprachiasmatic deafferentation and only about 15% of the neurohormone was found in the ipsilateral half of the median eminence after unilateral retrochiasmatic or complete deafferentation. The median eminence somatostatin showed practically no change after unilateral preoptic deafferentation, while it was reduced by about 50, 60 and 80% in the ipsilateral half median eminence after a unilateral suprachiasmatic, retrochiasmatic and complete deafferentation, respectively. The results are consistent with the assumption that the majority of the LHRH perikarya projecting to the median eminence are located partly in the preoptic-anterior hypothalamic area and partly in brain regions in front of or above this area. Most of the somatostatin perikarya with terminals in the median eminence are in the preoptic-anterior hypothalamic region.

Afferent Pathways↗
PubMed1982

Drug-receptor interaction on plasmid elimination by phenothiazines and imipramine in Escherichia coli.

Plasmid elimination in Escherichia coli by a quaternary amine of chlorpromazine was demonstrated on different incompatibility groups of plasmid. The biological effect of the drug depends partly on the host bacteria and partly on the plasmid itself. Various receptor substrates such as adenosine, dopamine, histamine and norepinephrine do not alter the plasmid elimination by promethazine and imipramine. None of the known drug-receptors studied are involved in drug binding of the bacteria. The direct membrane action of imipramine and promethazine was demonstrated in electron microscopic studies and alterations in the bacterial membrane such as discontinuities, phase separation or rarely extensive lytic alterations were observed. Magnesium ions prevent the ultrastructural membrane alterations caused by imipramine and promethazine. There is some evidence that the drugs bind to two different receptor sites simultaneously on the plasmid replication site. The first and strongest binding has to be ionic through the side chain amino group, displacing the bivalent cations. In turn, the two aromatic rings of the fixed (ionically bound) drug molecules bind weakly through pi-electrons, hydrophobically or by a charge transfer complex. This weaker binding together with the ionic one are essential for biologic action and lead to the inhibition of plasmid replication. A schematic model of the effect of tricyclic psychotropic drugs on the bacterial membrane is proposed.

Binding Sites↗
PubMed1982

The effect of ring-substituted and quaternary chlorpromazine derivatives on the survival of the NK/Ly ascites tumor bearing mice.

The effect of quaternary chlorpromazines like-methiodide, allylammonium chloride, -octylammonium iodide, benzylammonium chloride, -phenacylammonium bromide, 9-phenanthryl-methylammonium bromide, trimethylene-bis-chlorpromazine-ammonium bromide and among the ring-substituted derivatives the 7-hydroxy-, 7,8-dihydroxy-, 7,8-dioxo-, 6,9-dihydroxy-, 6,9-dioxo-chlorpromazines and the chlorpromazine-5-oxide on the prolongation of survival time of NK/Ly ascites tumor bearing mice was studied. The intraperitoneally administered quaternary chlorpromazine derivatives in 10-25 mg/kg daily dose did not increase the life span of the animals, and did not prevent the development of the ascites tumor. However some ring system substituted chlorpromazines such as the 7,8-dioxo- and 6,9-dioxo-derivatives markedly increased the survival time of the tumor bearing mice and reduced the ascite volume in 10 mg/kg body weight dose.

Animals↗
PubMed1982

Determination of ethinylestradiol in tablets by quantitative TLC method.

A new quantitative TLC method was developed for the determination of ethinylestradiol in tablets. The possible adsorption of ethinylestradiol on the starch can be avoided by enzymatic degradation, which enabled the easy extraction of the active ingredients from the tablet powder. The quantitative evaluation of the separated compounds was performed by densitometry at a wavelength of 280 nm. The relative standard deviation of the method was found to be better than +/- 2.6% in every case except Ambosex tablet where this value was +/- 4.7%. On the basis of the results obtained the method can be proposed for the routine analysis of tablets containing small amount of ethinylestradiol.

Chromatography, Thin Layer↗
PubMed1981

HnRNP particles from Drosophila melanogaster cells.

The isolation and characterization of HnRNP from cultured Drosophila melanogaster cells is described. HnRNP particles were extracted from the purified nuclei of sonication in the presence of rat liver cytosol RNAse inhibitor. The nuclear extract was centrifuged on a 15-30% sucrose gradient. The main part of the heterogeneous HnRNP material was localized in the 30 to 80S region of the sucrose gradient. According to the results of re-sedimentation studies the monomer particle was 45S. The buoyant density of HnRNP particles from different regions of the sucrose gradient were equal to approximately 1.4. The protein composition of the particles was analyzed by urea-SDS-polyacrylamide gel electrophoresis. There are five main and a few minor bands. Only the main polypeptides have a slightly higher molecular weight than those of the major polypeptides of 30S subparticles from rat liver nuclei. According to electron = microscopic studies the particles are heterogeneous and the average diameter was found to be 24-26 nm both on the basis of negative contrast and platinum-palladium shadowed pictures.

Animals↗
PubMed1981

(D-Met2,Pro5)-enkephalinamide-induced blockade of ovulation and its reversal by naloxone in the rat.

The effects of (D-Met2,Pro5)-enkephalinamide--a superactive enkephalin analogue--on the preovulatory discharge of gonadotrophic hormones and on ovulation were investigated. Injection of the opioid (16 nmol) into a lateral cerebral ventricle of regularly cycling female rats immediately before the critical period on the day of proestrus resulted in a blockade of ovulation and in a concomitant depression of the preovulatory plasma luteinizing hormone and follicle-stimulating hormone levels. A smaller dose of the opioid (2 nmol) did not inhibit ovulation. The inhibition of the preovulatory gonadotrophic hormone discharge and the blockade of ovulation by the opioid were reversed by naloxone administration. Our data are consistent with the view that the endogenous opioid peptides may be involved in the physiological regulation of the central neural events which lead to ovulation in the rat.

Animals↗
PubMed1981

Effect of chlorpromazine on conjugal plasmid transfer and sex pili.

The major tranquillizer chlorpromazine (Cpz) inhibited the conjugal transfer of R and F'lac plasmids. The frequency of transfer of R-144 and R-100 plasmids was reduced with 2-3 log by Cpz at a concentration of 50-100 microgram/ml, while the frequency of RM-98 plasmid did not change under the same conditions. Cpz at 100 microgram/ml was an effective inhibitor of the transfer of F'lac plasmid. By means of electron microscopy and plaque assay, 100 microgram/ml Cpz was shown to reduce the adsorption rate of male specific ribonucleic acid phages MS-2 to the sides of F-pili. Common pili and flagellae seemed to be intact, but sex pili probably retracted in the presence of Cpz.

Adsorption↗
PubMed1981

[Orchidopexy and fertility].

The authors report on experiences which they could prove during the last ten years (1970-1979) in disturbances of a descent of the testis. Particular consideration is given to the orchidopexy in later childhood or adolescence and to fertility. The importance of the right time of operation and the technique of the intervention protecting the tissue are emphasized.

Adolescent↗
PubMed1981

Antitumor activity of flavonoids on NK/Ly ascites tumor cells.

Among the various flavonoids, rutin and quercetin increased the survival time of mice inoculated with NK/Ly ascites tumor cells. The best results were obtained when the mice were given 2.0 mg rutin twice daily for 8 days. The O-silyl-substituted rutin and quercetin were less effective than rutin or quercetin themselves. Besides rutin, quercetin and morin two other flavonoids, luteolin and pelargonidin also exerted growth inhibitory effects on NK/Ly ascites tumor cells cultures in vitro.

Animals↗
PubMed1980

Lack of correlation between intercalation and plasmid curing ability of some tricyclic compounds.

Some tricyclic psychotropic drugs are known to have plasmid curing activity. The interaction with DNA of three plasmid curing (chlorpromazine, amitriptyline, imipramine) and four ineffective (methylene blue, 7,8-dioxo-chlorpromazine, thiazinamium, chlorpromazine sulphoxide) compounds was studied by fluorescence polarization and circular dichroism methods. Among the seven compounds three, namely chlorpromazine, 7,8-O2-chlorpromazine, and methylene blue showed an intercalation effect. Other phenothiazines such as chlorpromazine sulphoxide and thiazinamium were not able to intercalate into Escherichia coli DNA, neither did the plasmid curing drugs amitryptyline and imipramine. It is concluded that the plasmid curing ability is not necessarily related to the intercalation ability.

Amitriptyline↗