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Biomedical subjects

R Müller

Publications and source records attributed to R Müller.

At least 325 records · Page 18Linked to original sources
PubMed1995

Cell cycle-regulated transcription in mammalian cells.

The periodic, phase-specific transcription of defined sets of genes is a hallmark of cell cycle progression in all organisms (1-3). In this article, we will summarise our current knowledge and views of the mechanisms governing the cross-coupling of cell cycle control and transcriptional regulation in mammalian cells, with particular emphasis on the transcription factor E2F and the retinoblastoma protein pRb (1-3). Excluded from this review will be the genomic response to mitogenic stimulation, which is part of the mitogen-triggered signal transduction cascades rather than a reflection of cell cycle regulation (4).

Animals↗
PubMed1995

Microbial production of specifically ring-13C-labelled 4-hydroxybenzoic acid.

When transformed with a recombinant vector carrying the ubiC gene (encoding chorismate pyruvate-lyase, EC 4.1.3.27) the triple mutant (Phe-, Trp-, Tyr-) Klebsiella pneumoniae 62-1 excretes 4-hydroxybenzoic acid instead of chorismic acid. The recombinant strain can be used to produce in high yield specifically ring-labelled 4-hydroxybenzoic acid from isotopically labelled glucose.

Anthranilate Synthase↗
PubMed1995

Dehalogenation of 4-chlorobenzoate. Characterisation of 4-chlorobenzoyl-coenzyme A dehalogenase from Pseudomonas sp. CBS3.

Pseudomonas sp. CBS3 is capable of growing with 4-chlorobenzoate as sole source of carbon and energy. The removal of the chlorine of 4-chlorobenzoate is performed in the first degradation step by an enzyme system consisting of three proteins. A 4-halobenzoate-coenzyme A ligase activates 4-chlorobenzoate in a coenzyme A, ATP and Mg2+ dependent reaction to 4-chlorobenzoyl-coenzyme A. This thioester intermediate is dehalogenated by the 4-chlorobenzoyl-coenzyme A dehalogenase. Finally coenzyme A is split off by a 4-hydroxybenzoyl-CoA thioesterase to form 4-hydroxybenzoate. The involved 4-chlorobenzoyl-coenzyme A dehalogenase was purified to apparent homogeneity by a five-step purification procedure. The native enzyme had an apparent molecular mass of 120,000 and was composed of four identical polypeptide subunits of 31 kDa. The enzyme displayed an isoelectric point of 6.7. The maximal initial rate of catalysis was achieved at pH 10 at 60 degrees C. The apparent Km value for 4-chlorobenzoyl-coenzyme A was 2.4-2.7 microM. Vmax was 1.1 x 10(-7) M sec-1 (2.2 mumol min-1 mg-1 of protein). The NH2-terminal amino acid sequence was determined. All 4-halobenzoyl-coenzyme A thioesters, except 4-fluorobenzoyl-coenzyme A, were dehalogenated by the 4-chlorobenzoyl-CoA dehalogenase.

Acyl Coenzyme A↗
PubMed1995

Cloning and expression of a haloacid dehalogenase from Pseudomonas sp. strain 19 S.

A dehalogenase gene specifying the utilization of a variety of haloacids by Pseudomonas sp. Strain 19S has been cloned and expressed in E. coli. Our cloning strategy employed specific amplification of a fragment homologous to Pseudomonas dehalogenase gene by Polymerase Chain Reaction (PCR). The PCR amplicon successfully acted as a probe to detect the dehalogenase gene in the Southern Blot of the digested Pseudomonas total DNA. Corresponding fragments were cloned into pUC 18 vector and amplified in E. coli MV 1190. One clone with a substantial dehalogenation activity carried a recombinant plasmid containing a 5.5 kb insert.

Cloning, Molecular↗
PubMed1995

[Detection of enzyme activity in decontaminated spices in industrial use].

A range of decontaminated species of industrial use have been examined for their enzymes (catalase, peroxidase, amylase, lipase activity). The genuine enzymes remain fully active in irradiated spices, whereas the microbial load is clearly reduced. In contrast steam treated spices no longer demonstrate enzyme activities. Steam treatment offers e.g. black pepper without lipase activity, which can no longer cause fat deterioration. Low microbial load in combination with clearly detectable enzyme activity in spices is an indication for irradiation, whereas, reduced microbial contamination combined with enzyme inactivation indicate steam treatment of raw material.

Amylases↗
PubMed1995

Three-dimensional finite element modelling of non-invasively assessed trabecular bone structures.

The three-dimensional microstructure of cancellous bone seems to be one of the key factors in the prediction of mechanical bone properties like bone strength or bone stiffness. In this paper trabecular bone structure was assessed nondestructively by means of high-resolution computed tomography (CT) with a spatial resolution of 250 microns. Mineralized bone was separated from bone marrow and muscle tissue with the help of a three-dimensional segmentation algorithm based on the analysis of directional derivatives. From the three-dimensional stack of CT slices a subvolume comparable in size (3.6 x 3.4 x 3.4 mm3) to standard histologic bone sections was selected. We refer to this subvolume as non-invasive bone biopsy. A new automated mesh generator was developed to create a three-dimensional finite element model of the non-invasive bone biopsy. Four-noded tetrahedron solid elements were used to guarantee a smooth surface representation. The aim of the presented work was to demonstrate the potential of high-resolution CT imaging in the prediction of the anisotropic material properties of cancellous bone. Preliminary results of the 3D finite element stress analysis are very promising. The predicted value of the apparent Young's modulus (564 MPa) is within the range reported for uniaxial compression testings of cancellous bone specimens.

Algorithms↗
PubMed1995

Transcriptional regulation during the mammalian cell cycle.

Progression of the cell cycle in mammalian cells, as in all other organisms, is associated with the phase-specific transcription of defined sets of genes. Such periodically expressed genes frequently encode proteins that either directly control cell-cycle progression or function in metabolic processes linked to the cell cycle, such as nucleotide and DNA biosynthesis. Here, I summarize our current knowledge and views of the mechanisms governing the coupling of cell-cycle control mechanisms to transcriptional regulation, with particular emphasis on the transcription factor E2F and its connections with cyclin-dependent kinases and the retinoblastoma gene family.

Animals↗
PubMed1995

Determinants of HIV infection and recent risk behaviour among injecting drug users in Berlin by site of recruitment.

This study investigated differences in prevalence and determinants of HIV infection, and in recent risk behaviour (previous 6 months) among injecting drug users (IDUs) who are in contact with different types of services for IDUs in Berlin. Participants (n = 557) were recruited from drug-free long-term treatment centres, a storefront agency and a syringe exchange bus. HIV seroprevalence was lowest (3.9%) at the treatment centres, and highest among IDUs at the storefront agency (20.7%). In logistic regression, independent risk factors for HIV infection were duration of injecting drug use, borrowing syringes in prison, sex with HIV-positive partners, and prostitution. Syringe sharing in prison was the most important independent determinant of HIV infection among all three subpopulations of IDUs. Participants entering long-term treatment were most likely, and IDUs at the syringe exchange bus were least likely to have borrowed and passed on syringes in the previous 6 months. In logistic regression, site of recruitment was independently associated with recent borrowing of syringes, but not with condom use. Injection of drugs other than heroin only, and injecting in prisons, were also independent predictors of recent borrowing. The results indicate that IDUs entering treatment form an important target group for health education. There is a need for AIDS prevention measures in prisons. The comparatively low levels of recent injection risk behaviour among IDUs at the syringe exchange bus suggest that this type of intervention may be effective in harm reduction.

Adult↗
PubMed1995

Young teenagers and access to alcohol in a Swiss canton: evidence from observational testing and from a telephone survey.

In the first part of the study, the readiness of bartenders and waiters to serve alcoholic beverages to young teenagers was studied. The fieldwork was conducted in a random sample of bars and restaurants in Lausanne and in villages of the canton of Vaud, where 13-year-old and 15-year-old boys ordered either beer or pastis (an aniseed-flavoured aperitif). Results showed that alcoholic beverages were very accessible to 13-year-old and 15-year-old youths although the minimum legal age for purchasing and consuming beer is 16 years and for pastis is 18 years: 81% of the test orders were served. An analysis of interaction of patterns between servers and clients suggested that time necessary to refuse orders may play an important role in explaining this result. In the second part of the study, knowledge and attitudes of owners and managers of bars, restaurants and different kinds of commercial outlet were studied in a telephone interview survey about the minimum legal age for purchasing and consuming alcoholic beverages. Only 17% of the respondents knew the correct minimum legal ages for purchasing and consuming alcoholic beverages.

Adolescent↗
PubMed1995

[Syringocystadenoma papilliferum of the outer ear canal].

Ceruminomata are tumours spreading from the ceruminous glands of the external auditory canal. Since 1894 190 cases have been described, but nomenclature is still confusing to some extent. Syringocystadenoma papilliferum is a special subgroup. 189 cases are reported in the literature; 11 tumours have been observed in the auditory canal. A further case is reported in this paper.

Adenoma, Sweat Gland↗
PubMed1995

Characterization of a keratinolytic serine proteinase from Streptomyces pactum DSM 40530.

A serine protease from the keratin-degrading Streptomyces pactum DSM 40530 was purified by casein agarose affinity chromatography. The enzyme had a molecular weight of 30,000 and an isoelectric point of 8.5. The proteinase was optimally active in the pH range from 7 to 10 and at temperatures from 40 to 75 degrees C. The enzyme was specific for arginine and lysine at the P1 site and for phenylalanine and arginine at the P1' site. It showed a high stereoselectivity and secondary specificity with different synthetic substrates. The keratinolytic activity of the purified proteinase was examined by incubation with the insoluble substrates keratin azure, feather meal, and native and autoclaved chicken feather downs. The S. pactum proteinase was significantly more active than the various commercially available proteinases. After incubation with the purified proteinase, a rapid disintegration of whole feathers was observed. But even after several days of incubation with repeated addition of enzymes, less than 10% of the native keratin substrate was solubilized. In the presence of dithiothreitol, degradation was more than 70%.

Amino Acid Sequence↗
PubMed1995

Plasma catecholamines, thrombocyte alpha 2- and lymphocyte beta 2-adrenoceptor densities in hypertensive patients with low or normal plasma renin concentrations.

The sympathetic nervous system is unique in the regulation of plasma renin, for it can stimulate or suppress renin release by activation of either renal beta- or alpha 2-adrenoceptors. The authors studied plasma renin concentration (PRC), noradrenalin and adrenalin levels in plasma, and the densities of lymphocyte beta 2-adrenoceptors and thrombocyte alpha 2-adrenoceptors in 25 hypertensive patients with either normal (11-40 mU/L; n = 9) or low PRC (0-10 mU/L; n = 14). There were no differences in plasma catecholamine levels and adrenoceptor densities between the two patient groups. A positive correlation (r = 0.66; P < 0.005) between beta 2-adrenoceptor density and PRC in the patient group with low PRC, and a negative correlation (r = -0.72; P < 0.01) between alpha 2-adrenoceptor density and plasma renin in patients with normal PRC were found. They conclude that adrenoceptor densities on blood elements and plasma catecholamines do not differ in low and normal renin hypertension. The significant correlations between adrenoceptor densities and PRCs may indicate that adrenoceptors on blood elements mirror adrenoceptor densities in the kidney and that tonic suppression of renin release through alpha 2-adrenoceptors is preserved in hypertensive patients with normal plasma renin levels.

Adult↗
PubMed1995

Prevalence and determinants of anti-HCV seropositivity and of HCV genotype among intravenous drug users in Berlin.

A cross-sectional study was carried out to identify risk factors for seropositivity for antibodies against hepatitis C virus (HCV) and to assess to the distribution and determinants of HCV genotypes among intravenous drug users (IVDUs). The study population consisted of 405 IVDUs. Serum specimens were tested for seromarkers for HCV, for human immunodeficiency virus (HIV), for hepatitis B virus (HBV) and for syphilis. HCV RNA determination by polymerase chain reaction (PCR) and virus typing were performed in a subsample of anti-HCV-positive specimens (n=135). Of the IVDUs, 83% were anti-HCV-positive, 18% HIV-infected, and 58% HBV (anti-HBc)-positive. Longer duration of intravenous drug use, syringe sharing in prison, and higher number of IDVU sex partners were independent risk factors for anti-HCV positivity. GCV RNA was detected in 76% of anti-HCV-positive IVDUs. HCV genotypes 1 (49%) and 3 (44%) were most commonly found. All the type 3 isolates were identified as subtype 3a, and 95% of the type 1 isolates as subtype 1b. In logistic regression analysis, HCV type 3a viraemia was significantly associated with lack of HIV infection and a higher number of sex partners. The results indicate that preventive measures are needed to reduce syringe sharing among IVDUs in prisons. Sexual contacts with other IVDUs may play a role in the HCV epidemic among IVDUs. In Germany, HCV type 3a infection appears to be much more common among IVDUs than among other HCV risk groups such as transfusion recipients or haemophiliacs.

Adolescent↗
PubMed1995

[Hoarseness].

Hoarseness is a cardinal symptom of laryngeal disease. It is a disturbance of the normal voice pitch that can be evaluated acoustically using the 'RBH scale' [R for roughness, B for breathiness, H for hoarseness]. Hoarseness lasting longer than three weeks or recurring must be evaluated by an ENT specialist or a phoniatrist. Causes of hoarseness include functional disorders of the voice, inflammation of the larynx, secondary changes of the vocal folds, polyps, cysts, edema, papillomas, tumors, trauma, or palsies of the vocal cords due to different reasons. Early diagnosis of malignant laryngeal tumors is a prerequisite for preserving voice quality. Functional disorders and unilateral palsies of the vocal folds are treated by logopedists. The therapy of choice for inflammations is relief of symptoms, and surgery is employed for organic lesions.

Diagnosis, Differential↗
PubMed1995

[Rotavirus gastroenteritis in homes for the aged--a neglected problem?].

Two outbreaks of gastroenteritis caused by rotavirus in geriatric wards are reported. In one case an abrupt beginning among the elderly was seen, in a second case the outbreak was gradual. Rotavirus gastroenteritis is common among children. In elderly people this illness is less often recognised. In this report epidemiologic features, the methods of diagnosis, the management and prevention of rotavirus infections of geriatric patients are discussed.

Aged↗
PubMed1995

Imprisonment: a risk factor for HIV infection counteracting education and prevention programmes for intravenous drug users.

OBJECTIVES: To examine changes of risk behaviour and its determinants as well as risk factors for HIV infection in intravenous drug users (IVDU) with particular attention to imprisonment and its risk patterns. SETTING: In 1993 a multisite cross-sectional study was carried out by standardized questionnaires and blood/saliva samples in which 612 IVDU from Berlin were enrolled. RESULTS: Multifactorial analysis revealed that the most important risk factor for HIV infection was needle-sharing in prison. In total, 353 IVDU (58%) reported reduced risk behaviour; changes related more to injection behaviour than sexual practices (91 versus 68%). Important determinants for needle-sharing during the last 6 months were intravenous drug use in prison, duration of drug-taking history, and knowledge of a negative HIV test. The most frequently reported reasons for current needle-sharing were having shared needles with only one regular partner (45%) and imprisonment (26%). CONCLUSION: Information campaigns and other prevention measures appear to have produced risk awareness in IVDU, and as a consequence, a reduction in risk behaviour. The situation in prisons (no sterile injecting equipment, no effective disinfectants), however, is counteractive to prevention measures implemented outside prisons. An important task for future strategies should be to enable IVDU to avoid HIV transmission while in prisons.

Adult↗