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R Müller

Publications and source records attributed to R Müller.

At least 523 records · Page 29Linked to original sources
PubMed1989

A novel metabolite in the microbial degradation of 2-chlorobenzoate.

A bacterium which utilizes 2-chlorobenzoate as sole source of carbon and energy was isolated from water and tentatively identified as a Pseudomonas sp. During growth on 2-chlorobenzoate, the chlorine substituent was released quantitatively and a metabolite accumulated in the culture medium. Based on thin-layer chromatography, high-pressure liquid chromatography and gas chromatography linked to mass spectrometry this compound was unequivocally identified as 2,3-dihydroxybenzoate, a compound not described before in the degradation of 2-chlorobenzoate.

Chlorobenzoates↗
PubMed1989

Two functionally different regions in Fos are required for the sequence-specific DNA interaction of the Fos/Jun protein complex.

THE products of the cellular and retroviral fos genes associate with other nuclear proteins, among them the transcription factor AP1/Jun (see ref. 3 for a review). The Fos/Jun complex binds to a specific symmetrical DNA recognition sequence (termed TRE), thus stimulating transcription of the respective gene. Here, we show that two distinct regions in Fos are required for the formation of a Fos/Jun/TRE complex. These are the leucine zipper, involved in the association with Jun, and a directly adjacent basic region. Specific amino-acid substitutions in this basic, presumably alpha-helical, region abolish the interaction of Fos/Jun with the TRE but not the association of the two proteins. The functionally crucial amino acids are located in a region of Fos which is structurally similar to the putative DNA-binding sites in Jun and in the yeast transcriptional activator GCN4 (refs 15 and 16).

Amino Acid Sequence↗
PubMed1989

The leucine repeat motif in Fos protein mediates complex formation with Jun/AP-1 and is required for transformation.

Cellular and viral Fos proteins form a tight complex with other nuclear proteins, including the transcription factor and proto-oncogene AP-1/Jun. We have mapped the c-Jun binding site in Fos to a region containing regularly spaced leucine residues recently suggested to interdigitate with a similar structure in Jun. Substitution of single or multiple leucine residues or the alteration of leucine phasing by insertion of additional amino acids reduces or abolishes the binding to Jun, while the substitution of other amino acids has no noticeable effect. These results strongly suggest that the formation of a "leucine zipper" mediates the interaction between Fos and Jun. We also show that the differential binding of the various Fos mutants correlates with their potential to trans-activate AP-1-dependent transcription and to induce morphological transformation.

Animals↗
PubMed1989

Tumor inhibiting properties of stereoisomeric [1,2-bis(3-hydroxyphenyl)ethylenediamine]dichloroplatinum(II)-compl exe s, Part I: Synthesis.

The synthesis of the stereoisomeric 1,2-bis(3-hydroxyphenyl)ethylenediamines (1-4) from meso-1,2-bis(2-hydroxyphenyl)ethylenediamine and 3-methoxybenzaldehyde by a diaza-Cope-rearrangement and subsequent ether cleavage with BBr3 and their conversion into the [1,2-bis(3-hydroxyphenyl)ethylenediamine]dichloroplatinum(II)-complexes with K2PtCl4 (1-PtCl2 - 4-PtCl2) is described.

Antineoplastic Agents↗
PubMed1989

Tumor inhibiting properties of stereoisomeric [1,2-bis(3-hydroxyphenyl) ethylenediamine]dichloroplatinum(II)-complexes, Part II: Biological properties.

The activity of stereoisomeric [1,2-bis(3-hydroxyphenyl)ethylenediamine] dichloroplatinum(II)-complexes (1-PtCl2,R,S; 2-PtCl2, R,R/S,S; 3-PtCl2, R,R; 4-PtCl2, S,S) on several tumor models (MDA-MB 231 breast cancer cell line; P 388 leukemia, mouse; L 1210 leukemia, mouse; L 5222 leukemia, rat; Ehrlich ascites tumor, mouse--wildtype; cisplatin-, etoposide-, cyclophosphamide-, and daunomycin-resistant, resp.) is described. For comparison the analogous [1,2-bis(4-hydroxyphenyl)ethylendiamine]dichloroplatinum (II)-complexes (5-PtCl2, R, S; 6-PtCl2, R,R/S,S; 7-PtCl2, R,R; 8-PtCl2, S,S) and cisplatin are used. 1-PtCl2 to 4-PtCl2 (OH in 3,3'-positions) show their maximum antitumor effect at lower doses than 5-PtCl2 to 8-PtCl2 (OH in 4,4'-positions). 2-PtCl2 and 6-PtCl2 (R,R/S,S) are more active than 1-PtCl2 and 5-PtCl2 (R,S). 4-PtCl2 and 8-PtCl2 (S,S) are superior to 3-PtCl2 and 7-PtCl2 (R,R). On the L 5222 leukemia 2-PtCl2 (R,R/S,S), 4-PtCl2 (S,S) and 8-PtCl2 (S,S) markedly surpass cisplatin. Strong effects are produced by 2-PtCl2 to 4-PtCl2 on the Ehrlich ascites tumor (wildtype, cisplatin-, etoposide-, cyclophosphamide-, and daunomycin-resistant, resp.). The combination of 4-PtCl2 with cisplatin results in a weakly synergistic effect.

Animals↗
PubMed1989

The product of a novel growth factor activated gene, fos B, interacts with JUN proteins enhancing their DNA binding activity.

We have identified a gene, fos B, encoding a nuclear protein of 338 amino acids presenting a 70% homology with c-fos, whose expression is activated during G0/G1 transition. Growth factor stimulation of quiescent cells leads to a rapid and transient accumulation of fos B mRNA, with kinetics similar to those of c-fos. The induction of fos B mRNA levels is in part due to a dramatic increase in the transcription of the gene. The half-life of fos B mRNA is in the order of 10-15 min. Both transcriptional activation and mRNA stability are substantially increased in the presence of protein synthesis inhibitors. Immunoprecipitation studies showed that fos B as c-fos protein, forms a complex in vitro with c-jun and jun B proteins in the absence of a target binding sequence. Gel retardation assays demonstrated that fos B protein positively influences the binding of c-jun and jun B proteins to an AP-1 binding consensus sequence, suggesting that fos B protein plays a role in control of gene expression.

Amino Acid Sequence↗
PubMed1989

[Indications and performance of diagnostic tympanotomy in children].

From 1983 to 1987 163 children with an air-conduction loss were admitted for otosurgical treatment to the ENT clinic of the Medical Academy in Dresden. Explorative tympanotomy was necessary in 11 cases, i.e. a proportion of 6 to 7%. Indications of such tympanotomy are progressive middle-ear deafness, alterations of the ear drum and posttraumatic conduction deafness. An essential indication is the suspicion of a tumour.

Adolescent↗
PubMed1989

Evidence for a new pathway in the bacterial degradation of 4-fluorobenzoate.

Six bacterial strains able to use 4-fluorobenzoic acid as their sole source of carbon and energy were isolated by selective enrichment from various water and soil samples from the Stuttgart area. According to their responses in biochemical and morphological tests, the organisms were assigned to the genera Alcaligenes, Pseudomonas, and Aureobacterium. To elucidate the degradation pathway of 4-fluorobenzoate, metabolic intermediates were identified. Five gram-negative isolates degraded this substrate via 4-fluorocatechol, as described in previous studies. In growth experiments, these strains excreted 50 to 90% of the fluoride from fluorobenzoate. Alcaligenes sp. strains RHO21 and RHO22 used all three isomers of monofluorobenzoate. Alcaligenes sp. strain RHO22 also grew on 4-chlorobenzoate. Aureobacterium sp. strain RHO25 transiently excreted 4-hydroxybenzoate into the culture medium during growth on 4-fluorobenzoate, and stoichiometric amounts of fluoride were released. In cell extracts from this strain, the enzymes for the conversion of 4-fluorobenzoate, 4-hydroxybenzoate, and 3,4-dihydroxybenzoate could be detected. All these enzymes were inducible by 4-fluorobenzoate. These data suggest a new pathway for the degradation of 4-fluorobenzoate by Aureobacterium sp. strain RHO25 via 4-hydroxybenzoate and 3,4-dihydroxybenzoate.

Alcaligenes↗
PubMed1989

Enzymatic dehalogenation of pentachlorophenol by extracts from Arthrobacter sp. strain ATCC 33790.

Arthrobacter sp. strain ATCC 33790 was grown with pentachlorophenol (PCP) as the sole source of carbon and energy. Crude extracts, which were prepared by disruption of the bacteria with a French pressure cell, showed no dehalogenating activity with PCP as the substrate. After sucrose density ultracentrifugation of the crude extract at 145,000 x g, various layers were found in the gradient. One yellow layer showed enzymatic conversion of PCP. One chloride ion was released per molecule of PCP. The product of the enzymatic conversion was tetrachlorohydroquinone. NADPH and oxygen were essential for this reaction. EDTA stimulated the enzymatic activity by 67%. The optimum pH for the enzyme activity was 7.5, and the temperature optimum was 25 degrees C. Enzymatic activity was also detected with 2,4,5-trichlorophenol, 2,3,4-trichlorophenol, 2,4,6-trichlorophenol, and 2,3,4,5-tetrachlorophenol as substrates, whereas 3,4,5-trichlorophenol, 2,4-dichlorophenol, 3,4-dichlorophenol, and 4-chlorophenol did not serve as substrates.

Arthrobacter↗
PubMed1989

Overproduced bacteriophage T4 gene 33 protein binds RNA polymerase.

Bacteriophage T4 gene 33 protein (gp33), which is required for viral late transcription, has been overproduced. The purified gp33 binds to RNA polymerase core from uninfected or T4-infected Escherichia coli, but the major E. coli transcription initiation factor, sigma 70, competed effectively for this binding.

Binding, Competitive↗
PubMed1989

Enhanced leukotriene C4 production by peripheral eosinophilic granulocytes from children with asthma.

Granulocytes and mononuclear cells were isolated from the blood of asthmatic and healthy children. Stimulation with ionophore A 23187 induced a significantly higher leukotriene C4 (LTC4) generation from granulocytes of asthmatic children than from granulocytes of healthy controls. In contrast, mononuclear cells from patients and controls did not differ in their ability to produce LTC4. Additional analysis showed that the difference in LTC4 generation of granulocytes was due to increased formation but not to decreased oxidative degradation of LTC4. Analysis of LTC4 generation of purified neutrophils and eosinophils revealed that LTC4 was generated almost exclusively by eosinophils and, in particular, the hypodense population. Granulocytes from patients with a history of severe asthma displayed a higher LTC4 formation than granulocytes from patients with less severe disease.

Adolescent↗
PubMed1989

Peripheral hemodynamics, blood viscosity, and the renin-angiotensin system in hemodialysis patients under therapy with recombinant human erythropoietin.

Treatment of renal anemia with rhEPO (120 U/kg body weight/hemodialysis) in transfusion-dependent patients on maintenance hemodialysis led to an increase in blood pressure, regional peripheral resistance and whole blood viscosity. Our results are in agreement with earlier findings that partial correction of renal anemia results in hemodynamic changes characterized by a fall in cardiac output together with an increase in blood pressure due to increased vascular resistance. The increase in whole blood viscosity correlated with the increase in regional peripheral resistance but not with the increase in mean arterial blood pressure. Thus, other regulating factors of vascular resistance must be involved. Correction of renal anemia does not influence the reninangiotensin system. However, peripheral responsiveness of vascular smooth muscles may have changed due to improved tissue oxygenation and thus leading to an increase in vasoconstriction.

Adult↗
PubMed1989

Degradation of 5-chloro-2-hydroxynicotinic acid by Mycobacterium sp. BA.

Bacteria with the ability to use 5-chloro-2-hydroxynicotinic acid as sole source of carbon and energy have been isolated from enrichment cultures with 2-hydroxynicotinic acid and 5-chloro-2-hydroxynicotinic acid. According to their morphological and physiological properties, these bacteria have been classified as Mycobacterium sp. The first metabolite in the degradation pathway is 5-chloro-2,6-dihydroxynicotinic acid. 2-Hydroxynicotinic acid had an inductive effect on the degrading enzymes. Chloride was released from 5-chloro-2-hydroxynicotinic acid, chloromaleic acid and chlorofumaric acid. A degradation pathway is proposed.

Fumarates↗
PubMed1989

Degradation of 2-chlorobenzoate by Pseudomonas cepacia 2CBS.

A bacterium was isolated from water by enrichment on 2-chlorobenzoate as sole source of carbon and energy. Based on morphological and physiological properties, this microorganism was assigned to the species Pseudomonas cepacia. The organism was designated Pseudomonas cepacia 2CBS. During growth on 2-chlorobenzoate, the chlorine substituent was released quantitatively, and a small amount of 2,3-dihydroxybenzoate accumulated in the culture medium. Mutants of Pseudomonas cepacia 2CBS were induced by treatment with N-methyl-N'-nitro-N-nitrosoguanidine. Some of these mutants produced catechol from 2-chlorobenzoate. Other mutants accumulated the meta-cleavage product of catechol, 2-hydroxy-cis,cis-muconic acid semialdehyde. In crude cell-free extracts of Pseudomonas cepacia 2CBS, an enzyme was detected which catalysed the conversion of 2-chlorobenzoate to catechol. Molecular oxygen, NADH and exogenous Fe2+ were required for activity. Stoichiometric amounts of chloride were released. Experiments with 18O2 revealed that both oxygen atoms in the hydroxyl groups of the product were derived from molecular oxygen. Thus, the enzyme catalysing the conversion of 2-chlorobenzoate was identified as 2-chlorobenzoate 1,2-dioxygenase (1,2-hydroxylating, dehalogenating, decarboxylating). 2-Chlorobenzoate 1,2-dioxygenase from Pseudomonas cepacia 2CBS was shown to be a multicomponent enzyme system. The activities of catechol 2,3-dioxygenase and catechol 1,2-dioxygenase were detected in crude cell-free extracts. The activity of catechol 2,3-dioxygenase was 60 times higher than the activity of catechol 1,2-dioxygenase, indicating that catechol is mainly degraded via meta-cleavage in Pseudomonas cepacia 2CBS. No enzyme was found which converted 2,3-dihydroxybenzoate, suggesting that this compound is a dead-end metabolite of 2-chlorobenzoate catabolism. A pathway for the degradation of 2-chlorobenzoate by Pseudomonas cepacia 2CBS is proposed.

Catechols↗
PubMed1989

Microbial metabolism of quinoline and related compounds. III. Degradation of 3-chloroquinoline-8-carboxylic acid by Pseudomonas spec. EK III.

Bacteria have been isolated with the ability to use 3-chloroquinoline-8-carboxylic acid as sole source of carbon and energy. According to their physiological properties, these bacteria have been classified as Pseudomonas spec. Two metabolites of the degradation pathway have been isolated and identified. The first metabolite was 3-(3-carboxy-3-oxopropenyl)-2-hydroxy-5-chloropyridine, the meta-cleavage product of 3-chloro-7,8-dihydroxyquinoline. The second metabolite, 5-chloro-2-hydroxynicotinic acid, was not further metabolized by this organisms.

Nicotinic Acids↗
PubMed1989

Effects of azelaic acid on sebaceous gland, sebum excretion rate and keratinization pattern in human skin. An in vivo and in vitro study.

The effects of azelaic acid (AZA) on the epidermis of 47 individuals (12 with normal skin, 15 with seborrheic skin and 20 suffering from acne) and on in vitro cultured keratinocytes are reported. Topical application of a 20% AZA cream significantly improved the lesions of acne patients, but failed to induce clinically detectable changes in normal or seborrheic epidermis. Complementary investigations clearly showed that AZA treatment failed to induce specific changes in sebum composition, excretion rate, or in the size of sebaceous glands, but modified epidermal keratinization. Keratohyalin granules and tonofilament bundles were reduced in size and number, mitochondria were swollen and the rough endoplasmic reticulum of malpighian keratinocytes enlarged. The infundibular epidermis of acne individuals showed marked reduction of the horny layer thickness, widening of the horny cell cytoplasm, transitional corneal cells, normalization of filaggrin distribution, and the comedo contained few bacteria and spores. In vitro, AZA exerted marked time- and dose-dependent antiproliferative cytostatic effects on cultured keratinocytes, with a 50% inhibitory dose of 20 mM, decreased some keratinocyte proteins (highly soluble fractions S2, keratohyalin macroaggregate R2, and non-cross-linked fibrous protein S4) and a 95 kD and a 35 kD protein of the cytosolic fraction. Mitochondria were frequently damaged and the rough endoplasmic reticulum enlarged. Our results indicate that AZA is an antikeratinizing agent, displaying antiproliferative cytostatic effects on keratinocytes and modulating the early and terminal phases of epidermal differentiation.

Acne Vulgaris↗