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G Scherer

Publications and source records attributed to G Scherer.

At least 145 records · Page 8Linked to original sources
PubMed1984

Isolation and characterization of the rat tyrosine aminotransferase gene.

Tyrosine aminotransferase (TAT; L-tyrosine:2-oxoglutarate aminotransferase, EC 2.6.1.5) from rat liver is subject to glucocorticoid, cAMP, and developmental control. To study the underlying regulatory mechanisms, the TAT structural gene was isolated from a lambda bacteriophage rat DNA library. Heteroduplex analysis revealed that the 2.4-kilobase-long TAT mRNA is encoded by a gene that extends over 11 kilobases and is interrupted by 11 introns. To characterize the presumptive control region, the DNA sequence around the 5' end of the gene was determined and the start site of transcription was identified by nuclease S1 protection experiments. A short sequence homology in an equivalent position relative to the cap site was detected between TAT and tryptophan oxygenase, another glucocorticoid-controlled gene from rat liver. This sequence is related to the sequence 5' T-G-T-T-C-T 3' found in regions of the long terminal repeat of mouse mammary tumor virus, which has been shown to interact with the glucocorticoid receptor [Scheidereit, C., Geisse, J., Westphal, H. M. & Beato, M. (1983) Nature (London) 304, 749-752].

Animals↗
PubMed1983

Cadmium concentrations in tobacco and tobacco smoke.

The amount of cadmium in tobacco depends on the variety and origin of the plant as well as on the analytical method used to determine cadmium. In the literature, cadmium concentrations in tobacco of between 0.5 and 5 ppm are reported. Modern German cigarette tobacco contains about 0.5-1.5 micrograms cadmium/cigarette. Of importance for the smoker is the amount of the metal in the mainstream smoke. The cadmium level in the mainstream smoke of modern cigarettes is reduced by means of filters and other construction features. The average Cd value of German filter cigarettes is less than 0.1 microgram/cigarette in mainstream smoke. An average daily intake of about 1 microgram cadmium by smoking 20 cigarettes can be calculated on the basis of an experimentally proved pulmonary retention rate of 50%. Pulmonary resorption rates relevant to uptake rates of cadmium by smoking are discussed. It can be assumed that cadmium uptake by smoking modern cigarettes has been reduced because of modifications in tobacco processing and cigarette construction in the last few decades.

Cadmium↗
PubMed1982

Isolation and characterization of the rat tryptophan oxygenase gene.

Tryptophan oxygenase (TO, EC 1.13.1.12) from rat liver is subject to glucocorticoid and developmental control. To study the mechanism of regulation, TO mRNA sequences and the chromosomal TO gene were cloned. From a cDNA library prepared from rat liver poly(A)+ RNA enriched for TO mRNA, a recombinant plasmid containing TO cDNA sequences was identified by translation of hybrid-selected RNA and immunoprecipitation with antibodies directed against TO. This cDNA clone hybridizes to a mRNA 2000 bases long that is inducible by dexamethasone. With this clone as probe we isolated from a bacteriophage lambda rat DNA library genomic clones which together span a region of 32 kilobase pairs (kb). Heteroduplex analysis revealed that the gene extends over 19 kb and is interrupted by at least 11 introns. To characterize the presumptive control region the DNA sequence around the 5' end of the TO gene was determined. S1 nuclease protection experiments revealed two separate start sites for TO mRNA transcription within this region.

Animals↗
PubMed1982

Isolation of cDNA clones coding for rat tyrosine aminotransferase.

Tyrosine aminotransferase (TyrATase; L-tyrosine: 2-oxoglutarate aminotransferase, EC 2.6.1.5) from rat liver is subject to glucocorticoid and cAMP as well as developmental control. To isolate DNA sequences encoding TyrATase, we constructed a cDNA library from rat liver poly(A)+RNA enriched for TyrATase mRNA. Recombinant plasmids were screened by differential colony hybridization to poly(A)+RNA isolated from adrenalectomized and dexamethasone-treated animals. Differentially hybridizing plasmids were then shown to contain TyrATase cDNA sequences by their ability to select a mRNA whose in vitro translation product is immunoprecipitable with antiserum against TyrATase. In confirmation, we detect mRNA homologous to TyrATase cDNA sequences in hepatoma cell lines known to contain TyrATase activity but not in a cell line lacking this activity. We show that treatment of rats with dexamethasone or N6,O2'-dibutyryladenosine 3',5'-cyclic monophosphate leads to a 5- to 10-fold increase in the amount of TyrATase mRNA.

Animals↗
PubMed1981

[Evidence that electrophoretic-mobility (EM) test is of no value for the diagnosis of cancer in children (author's transl)].

After incubation with encephalitogenic factor (EF) the capacity of lymphocytes to inhibit the migration of tanned, stabilized sheep-erythrocytes in the electric field was tested in 133 children (52 tumor- and 81 control patients). Tumor patients (on and off treatment) as well as children suffering from non-inflammatory diseases showed a significant migration inhibition as compared with healthy controls (p less than 0.05). However, in only 3/23 patients on, and 3/35 off therapy, an unequivocal inhibition of more than 8% could be demonstrated. The repeated examination of 8 individual patients yielded an unsatisfactory reproducibility; results were independent of the EF concentration ranging between 200-600 microgram EF/ml. We think that the EM-Test provides no useful information for the detection of malignant disease in children.

Adolescent↗
PubMed1979

Functional analysis of the replicator structure of lambdoid bacteriophage DNAs.

In our hybrid-plasmid reconstruction analysis of lambda (lambdoid) DNA signal structures involved in phage DNA replication, we have detected a dual system alternatingly able to initiate a first primer-RNA synthesis. Both of them--the major, primase-dependent ori system and the minor and usually suppressed, RNA-polymerase-dependent oop system--act in conjunction with a common signal structure for inception of DNA synthesis. It appears that in situations such as this, where one has to deal with the existence of regular as well as backup systems serving the same function, straightforward conclusions are no longer possible in their genetic analysis. For example, even though the oop-DNA segment can be deleted entirely from bacteriophage lambda DNA without disturbing its ability to replicate, it may not be valid to conclude that the oop system has no function in DNA replication. Dual systems of this type or organization in general have also been observed previously for some other replicons such as the R-factors R6-5 and R6K (Timmis et al. 1978; Crosa et al., this volume) or the F factor (Helinski et al., this volume), and they may be more common than presently expected.

Bacteriophage lambda↗
PubMed1978

Nucleotide sequence of cro, cII and part of the O gene in phage lambda DNA.

A nucleotide sequence comprising 960 base pairs of bacteriophage lambda DNA has been determined. The sequence includes the entire genes of the regulatory proteins cro and cII, and part of the O gene, together with control elements for their transcription and translation. The right-hand boundaries of the lambdaimm434 and lambdaimm21 substitutions and the cy42 mutation have been located.

Base Sequence↗
PubMed1978

Nucleotide sequence of the O gene and of the origin of replication in bacteriophage lambda DNA.

The nucleotide sequence of the O gene in bacteriophage lambda DNA is presented. According to two possible initiator codons, the primary structure of the O protein deduced from the DNA sequence consists of 278 or 299 amino acid residues. Structure and function of the O protein--one of the two phage initiator proteins for lambda DNA replication--are discussed in the light of a secondary structure model for the O protein. The central part of the O gene contains a cluster of symmetrical sequences extending over 160 base pairs. The point mutation of the cis-dominant replication mutant ti12 is located in this region.

Amino Acid Sequence↗
PubMed1978

Participation of L-ascorbate:ferricytochrome b5 oxidoreductase in ascorbate-dependent fatty acid desaturation of rat liver microsomes.

The microsomal enzyme ascorbate-cytochrome b5 reductase participates in the ascorbate-dependent fatty acid desaturation. Three pieces of evidence are given for this statement: 1) Comparison of the rate of ascorbate-dependent oleate formation with the rate of reduction of cytochrome b5 in microsomes and in the isolated detergent form shows that only the enzymatic reduction of cytochrome b5 is fast enough to support oleate formation; 2) added enriched ascorbate-cytochrome b5 reductase increases the rate of return of stearoyl-CoA oxidised cytochrome b5 back to the reduced state; 3) addition of enriched ascorbate-cytochrome b5 reductase increases the rate of ascorbate-dependent oleate formation in rat liver microsomes.

Animals↗
PubMed1977

DNA base sequence of the po promoter region of phage lamdba.

The sequence of a 123 base pair HpaII restriction fragment of bacteriophage lamdba DNA has been determined by the dimethylsulphate-hydrazine technique. Of this fragment 65 nucleotide pairs are transcribed into the 5' proximal part of the oop RNA. The remaining 58 nucleotide pairs preceding the start point of transcription show homologies to the lamdbaL and lamdbapR promoter regions, and are concluded to contain the lamdbapo promoter sequence.

Base Sequence↗
PubMed1974

Mechanism of alpha factor biosynthesis in Saccharomyces cerevisiae.

The biosynthesis of alpha factor, a mating-type-specific regulatory oligopeptide which is secreted by Saccharomyces cerevisiae cells of alpha mating type, was studied. In batch cultures only small amounts of the peptide were synthesized during the exponential growth phase. During the stationary phase, alpha factor was produced at a constant rate and accumulated in the culture medium. Inhibition of translation in wild-type cells by cycloheximide, or in mutant strains under conditions which blocked protein or ribonucleic acid (RNA) synthesis completely inhibited the production of alpha factor. These results indicate that the factor is produced by ribosomal translation of a specific messenger RNA and not by an extraribosomal mechanism of peptide synthesis.

Carbon Radioisotopes↗
PubMedDate not supplied

The role of vasopressin in the nicotine-induced stimulation of ACTH and cortisol in men.

Experimental evidence indicates that arginine vasopressin (AVP) contributes to the release of ACTH under certain conditions. The present study investigates the role of vasopressin as a secretagogue of ACTH during cigarette smoking or nicotine infusion with additional injection of corticotropin releasing hormone (CRH) and using the specific AVP antagonist d(CH2)5Tyr(Me)-AVP. We first tested the effect of the AVP antagonist (10 micrograms/kg body weight i.v.) on ACTH and cortisol release following cigarette smoking in 15 healthy young male smokers. Smoking led to marked increments in plasma nicotine and to a small rise in plasma ACTH and cortisol. Mean plasma ACTH and cortisol levels were at no time significantly altered by the antagonist. This might be due to a slight agonistic effect of the AVP antagonist, to high interindividual variability of the ACTH and cortisol responses after smoking or to a negligible role of AVP in smoking-induced ACTH release. In a second study we performed the following tests in six healthy male non-smokers: (1) nicotine infusion (1.0 micrograms/kg body weight per min); (2) CRH i.v. (100 micrograms); (3) AVP antagonist i.v. (5 micrograms/kg); (4) nicotine infusion plus CRH i.v.; (5) nicotine infusion plus AVP antagonist i.v.; (6) nicotine infusion plus CRH and AVP antagonist i.v.; and (7) sham infusion. Nicotine infusion led to greater increments of AVP, ACTH and cortisol than smoking without causing nausea. Peak nicotine levels after nicotine infusion were lower than after smoking. The AVP antagonist in the reduced dosage given alone had no effect on hormone levels. However, it slightly attenuated the effect of nicotine on ACTH and cortisol (P less than 0.05, ANOVA).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Uptake of tobacco smoke constituents on exposure to environmental tobacco smoke (ETS).

For the purpose of risk evaluation, passive smoking is frequently regarded as low-dose cigarette smoking. However, since the physical, chemical and biological properties of mainstream smoke (MS), which is inhaled by the smoker and environmental tobacco smoke (ETS), which is breathed by the passive smoker are quite different, risk extrapolation from active smoking to passive smoking is of doubtful value. In a series of experimental exposure studies we compared the uptake of tobacco smoke constituents by active and passive smoking. The results show that biomarkers which were found to be elevated after experimental ETS exposure, such as nicotine and cotinine in plasma and urine as well as thioethers in urine, indicate gas-phase exposure in passive smokers, but particle-phase exposure in active smokers. Biomarkers which should indicate the uptake of particle-bound, genotoxic substances with ETS, such as urinary mutagenicity, metabolites of polycyclic aromatic hydrocarbons (PAH) and DNA adducts, were not found to be elevated even after extremely high ETS exposure. From these results we conclude that a risk evaluation for passive smoking on the basis of dosimetric data is currently not possible.

Acetylcysteine↗