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R Gerber

Publications and source records attributed to R Gerber.

At least 55 records · Page 3Linked to original sources
PubMed1987

Injections of deuterated tryptamine into the nucleus accumbens of the rat: effects on locomotor activity and monoamine metabolism.

Previous studies have shown that the systemic injection of tryptamine stimulates locomotion in rats and that the nucleus accumbens, a region involved in locomotion, contains the largest concentrations of binding sites for tryptamine in the brain of the rat. The present study examined the behavioral and neurochemical effects of bilateral injections into the accumbens of a deuterated analog of tryptamine, a,a-[2H]tryptamine. Injections of 25 micrograms a,a-[2H]tryptamine increased movements in rats at 25-70 min after injection and increased vertical (rearing) activity at 25-40 min. Injections of 50 micrograms of a,a-[2H]tryptamine produced a transient suppression of movement and vertical activity at 5-15 min, followed by increases in these activities at 40-65 min after injection that were comparable to the increases elicited by 10 micrograms of d-amphetamine. At 30 min after the injection of 50 micrograms a,a-[2H]tryptamine the concentration of dopamine in the nucleus accumbens was increased by 87%, and was preceded by a transient decrease in the level of the metabolite of dopamine homovanillic acid. The levels of 5-hydroxytryptamine and its major metabolite, 5-hydroxyindoleacetic acid in the nucleus accumbens were not changed. Thus, a,a-[2H]tryptamine may interact with tryptamine receptors in the nucleus accumbens to modulate locomotor behavior through mesolimbic dopamine neurons.

Animals↗
PubMed1986

Glycopeptide antibiotics: a mechanism-based screen employing a bacterial cell wall receptor mimetic.

The evolution of a highly targeted screening program for the discovery of antibiotics of the glycopeptide (vancomycin) class is described. A holistic approach was utilized which optimized not just screening techniques but also the selection of candidate producer cultures and their growth under conditions which enhanced production of target compounds. Two screen techniques were utilized; differential inhibition of a vancomycin-resistant strain and its susceptible parent, and a specific antagonism screen using the reversal of glycopeptide activity by a tripeptide analog of the glycopeptide receptor, diacetyl-L-lysyl-D-alanyl-D-alanine. The latter screen was 2- to 32-fold more sensitive to known glycopeptides than the former, and was absolutely specific, yielding no false positive responses. The use of the tripeptide antagonism assay, combined with optimized culture selection and growth conditions yielded novel glycopeptide antibiotics at a rate of 1 per 320 cultures screened. With a holistic approach to screening and properly optimized techniques, large numbers of cultures do not need to be examined in order to discover novel antibiotics.

Actinomycetales↗
PubMed1986

Biosynthetic studies of aridicin antibiotics. II. Microbial transformations and glycosylations by protoplasts.

In connection with the biosynthetic studies of the aridicin antibiotics in Kibdelosporangium aridum, various microorganisms, known to produce related glycopeptide antibiotics, have been examined for their glycosylating activity. A number of strains were found to mannosylate the aridicin aglycone, while Actinoplanes teichomyceticus was found to have deacylating activity as well. A protoplast system of K. aridum was developed and was found to possess novel glycosylating activity in addition to the mannosylating activity which was also present in the whole cells. Effects on the glycosylating activity by various membrane solubilizing agents have been discussed.

Actinomycetales↗
PubMed1985

SCH 23390 dissociated from conventional neuroleptics in apomorphine climbing and primate acute dyskinesia models.

SCH 23390 induced only a negligible incidence of the acute dyskinetic syndrome, a predictor of neuroleptic-induced extrapyramidal liability, in squirrel monkeys. However, haloperidol-induced dyskinesias were potentiated by SCH 23390 and were blocked by the D-1 agonist, SKF 38393. When administered orally or intraperitoneally to mice, SCH 23390 showed a considerably wider dose separation than did conventional neuroleptics between antagonism of apomorphine climbing and antagonism of stereotyped sniffing. Clinically relevant distinctions may exist between D-1 and D-2 antagonists, with D-1 antagonists (exemplified by SCH 23390) showing lower, although possibly not negligible, potential to cause extrapyramidal side effects.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1985

Antagonism of L-5-hydroxytryptophan-induced head twitching in rats by lisuride: a mixed 5-hydroxytryptamine agonist-antagonist?

Lisuride antagonized L-5-hydroxytryptophan (5-HTP)-induced head twitches at doses lower than those sufficient to induce the serotonin (5-HT) syndrome. Among several other 5-HT agonists tested, only LSD and 1-(m-trifluoromethylphenyl)-piperazine (TFMPP) shared this paradoxical profile. Assessment of various dopamine (DA) agonists revealed a lack of correlation between DA-mediated stereotyped behavior (indicative of postsynaptic DA agonism) and blockade of 5-HTP-induced head twitches. Lisuride displaced specific ligand binding from putative S1a, S1b and S2 receptors at nanomolar concentrations, and other drugs that blocked 5-HTP-induced head twitches also displaced binding at S2 sites. It is proposed that lisuride may have agonist properties at S1a receptors mediating the 5-HT syndrome but antagonist properties at S2 receptors mediating 5-HTP-induced head twitching.

5-Hydroxytryptophan↗
PubMed1985

Differential antagonism by proglumide of various CCK-mediated effects in mice.

Proglumide has been reported to antagonize sulfated cholecystokinin octapeptide (CCK-8) in peripheral tissue and in neurophysiological single unit preparations. The present studies attempt to extend this reported antagonism to several actions of CCK-8 in mice in vivo. For comparison with proglumide, the antagonist activity of naloxone against CCK-8 has also been evaluated. Proglumide (150 mg/kg) antagonizes hot plate latency elevations produced by a moderate (0.17 mg/kg s.c.) dose of CCK-8, but not that by a higher (1.0 mg/kg) dose. The effects of intracerebroventricularly (i.c.v.) administered CCK-8 (0.3 micrograms) are also blocked by proglumide i.p. or i.c.v. Naloxone (0.5 mg/kg s.c.) significantly antagonizes the elevated hot plate latencies induced by CCK-8 i.c.v. (3.0 micrograms) and s.c. (3.0 mg/kg). Proglumide antagonizes the motor activity suppressant effects of CCK-8, but only at a high proglumide dose (150 mg/kg i.p.) and low CCK-8 doses. Naloxone (3.0 mg/kg) is not effective against CCK-8 in motor activity. The hypothermia induced by CCK-8 cannot be antagonized either by proglumide at doses up to 150 mg/kg i.p. or by naloxone at doses up to 3.0 mg/kg s.c. In vivo, proglumide may be considered as a weak antagonist of CCK-8 and the possibility exists that various actions of CCK-8 may be differentiated by their relative responsiveness to proglumide-induced antagonism.

Animals↗
PubMed1983

Pressured pattern or type A behavior in patients with peripheral arteriovascular disease: controlled retrospective exploratory study.

The question as to whether a specific behavior or type A pattern is limited to patients with coronary artery disease, or is found in atherosclerotic disease, in general, is explored. The interrelationship between a pattern of "pressured" behavior, assessed by open ended interviews, type A behavior, determined by the Bortner test, and peripheral atherosclerotic disease was investigated in a controlled retrospective study which compared three groups of 13 patients each: intermittent claudication (IC), intermittent claudication combined with coronary artery disease (CADIC) and a control group of patients without vascular disease (WVD). A pressured behavior pattern, assessed by interview, was found to be most prominent in the CADIC group, and least in the control group. The subjects with arteriovascular disease tended to exert more control over people compared to the WVD patients (Fisher's exact probability test, p = 0.05). The tendency to type A behavior, measured by means of the Bortner scale, also differentiated the three groups with CADIC scoring highest and WVD scoring lowest (analysis of variance, F = 3.944, p less than 0.05). IC patients present personality features of proneness to coronary disease. The pattern of "pressured" and type A behavior seem to correlate with the number of vascular areas involved in atherosclerotic disease.

Coronary Disease↗
PubMed1981

[Computer tomography (CT) in the choice of treatment and the planning of percutaneous transhepatic biliary drainage in obstructive jaundice due to tumour (author's transl)].

We have performed percutaneous transhepatic biliary drainage on 27 patients; of these, thirteen were examined by CT before and after the procedure. Our experience suggests that CT or sonography is indicated every case of obstruction due to tumour in order to: 1. Decide on treatment by a non-invasive method thereby saving the patient an unnecessary laparotomy and 2. Plan the biliary drainage accurately, leading to the lowest possible number of complications.

Aged↗
PubMed1977

[The technique of intracameral transplants applied to the study of experimental embryological problems concerning odontogenesis (author's transl)].

Two experimental embryological problems concerning odontogenesis are investigated using the technique of intracameral transplants in mice: --the presence of odontogenetic material in the mandibular arches of the 9 day mouse embryo, --the degree of specificity of the epitheliomesenchymatous interact-ons in the region of the tooth of the mouse and the rabbit. The tolerance of the recipient eye has been studied: --in the case of homografts, --in the case of heterografts. The indications and limiting factors of the method are specified within the framework of the chosen experimental conditions, taking into account the rejection phenomena manifested in the case of the heterografts.

Ameloblasts↗