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O Müller

Publications and source records attributed to O Müller.

At least 19 recordsLinked to original sources
PubMed2001

Cdc42p functions at the docking stage of yeast vacuole membrane fusion.

Membrane fusion reactions have been considered to be primarily regulated by Rab GTPases. In the model system of homotypic vacuole fusion in the yeast Saccharomyces cerevisiae, we show that Cdc42p, a member of the Rho family of GTPases, has a direct role in membrane fusion. Genetic evidence suggested a relationship between Cdc42p and Vtc1p/Nrf1p, a central part of the vacuolar membrane fusion machinery. Vacuoles from cdc42 temperature-sensitive mutants are deficient for fusion at the restrictive temperature. Specific amino acid changes on the Cdc42p protein surface in these mutants define the putative interaction domain that is crucial for its function in membrane fusion. Affinity-purified antibodies to this domain inhibited the in vitro fusion reaction. Using these antibodies in kinetic analyses and assays for subreactions of the priming, docking and post-docking phase of the reaction, we show that Cdc42p action follows Ypt7p-dependent tethering, but precedes the formation of trans-SNARE complexes. Thus, our data define an effector binding domain of Cdc42p by which it regulates the docking reaction of vacuole fusion.

Adenosine Triphosphatases↗
PubMed2001

Effect of zinc supplementation on malaria and other causes of morbidity in west African children: randomised double blind placebo controlled trial.

OBJECTIVE: To study the effects of zinc supplementation on malaria and other causes of morbidity in young children living in an area holoendemic for malaria in west Africa. DESIGN: Randomised, double blind, placebo controlled efficacy trial. SETTING: 18 villages in rural northwestern Burkina Faso. PARTICIPANTS: 709 children were enrolled; 685 completed the trial. INTERVENTION: Supplementation with zinc (12.5 mg zinc sulphate) or placebo daily for six days a week for six months. MAIN OUTCOME MEASURES: The primary outcome was the incidence of symptomatic falciparum malaria. Secondary outcomes were the severity of malaria episodes, prevalence of malaria parasite, mean parasite densities, mean packed cell volume, prevalence of other morbidity, and all cause mortality. RESULTS: The mean number of malaria episodes per child (defined as a temperature >/=37.5 degrees C with >/=5000 parasites/microliter) was 1.7, 99.7% due to infection with Plasmodium falciparum. No difference was found between the zinc and placebo groups in the incidence of falciparum malaria (relative risk 0.98, 95% confidence interval 0.86 to 1.11), mean temperature, and mean parasite densities during malaria episodes, nor in malaria parasite rates, mean parasite densities, and mean packed cell volume during cross sectional surveys. Zinc supplementation was significantly associated with a reduced prevalence of diarrhoea (0.87, 0.79 to 0.95). All cause mortality was non-significantly lower in children given zinc compared with those given placebo (5 v 12, P=0.1). CONCLUSIONS: Zinc supplementation has no effect on morbidity from falciparum malaria in children in rural west Africa, but it does reduce morbidity associated with diarrhoea.

Diarrhea↗
PubMed2001

Microplate enzyme-linked immunosorbent assay for the detection of primary DNA alterations based on the interaction with UvrA/UvrB.

An enzyme-linked microplate immunoassay for the analysis of primary DNA lesions is described. The assay principle is based on the interaction of the bacterial DNA repair proteins UvrA and UvrB with DNA and on the immunodetection of UvrB forming a stable complex with covalently modified nucleotides. Using this technique we were able to detect damages in genomic DNA induced by uv light and by several different genotoxic agents. The detection sensitivity of the method reaches down to the nanomolar range of the mutagenic compound depending on the type of the DNA alteration. The method might be used in automated high-throughput studies.

Adenosine Triphosphatases↗
PubMed2001

The novel ependymin related gene UCC1 is highly expressed in colorectal tumor cells.

Normal cells differ from malignant tumor cells in the transcription levels of many different genes. Two colorectal tumor cell lines were compared with a normal colorectal cell line by differential display reverse transcription PCR to screen for tumor cell specific differentially transcribed genes. By this strategy the upregulation of a novel gene was detected designated as 'upregulated in colorectal cancer gene-1' (UCC1). The UCC1 gene transcript level is increased in cultured tumor cells and in two out of three analyzed colorectal tumor tissue specimens compared to normal cultured cells and to corresponding normal tissue samples. Remarkably, the UCC1 protein shows significant sequence similarity to the highly divergent piscine glycoproteins termed ependymins which are synthesized by leptomeningeal fibroblasts and secreted into the cerebrospinal fluid.

Amino Acid Sequence↗
PubMed2001

Semiquantitative reverse transcription-polymerase chain reaction with the Agilent 2100 Bioanalyzer.

We have applied a method to monitor mRNA expression in a semiquantitative fashion on the Agilent 2100 Bioanalyzer. The method was originally described in 1994 by Wong et al. and referred to as the "primer-dropping" method. This polymerase chain reaction (PCR) technique uses multiple sets of primer pairs in a coamplification reaction that amplifies the target of interest within a predetermined range specific for each target. Separation, detection and quantification of PCR products were accomplished using the Agilent 2100 Bioanalyzer in conjunction with the DNA 500 and the DNA 1000 Lab-Chip kits for the detection of DNA fragments with a maximum size of 500 and 1000 bp, respectively. Using primers specific for the inducible form of hsp72 and primers for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an internal standard we were able to rapidly monitor and quantify inducible hsp72-mRNA expression.

Carcinoma, Hepatocellular↗
PubMed2001

Increase of adenomatous polyposis coli immunoreactivity is a marker of reactive astrocytes in Alzheimer's disease and in other pathological conditions.

Mutations in the adenomatous polyposis coli (APC) tumor suppressor gene are responsible for colon cancer in familial adenomatous polyposis coli and in many sporadic colorectal tumors. The product of the APC gene is also essential for normal development and is expressed in the adult brain. We have investigated the immunocytochemical localization of APC in the temporal cortex and hippocampus of normal human brain, in Alzheimer's disease (AD) and in several other neuropathological conditions. APC was expressed in neuronal cell bodies and dendrites both in control subjects and in patients with different diseases. In addition, a high APC expression was observed in a proportion of fibrillary and glial fibrillary acidic protein-positive astrocytes in AD. Furthermore, in AD the proportion of APC-positive astrocytes was higher in astrocytes associated with beta-amyloid (Abeta) deposits in senile plaques than in astrocytes not associated to Abeta deposits. APC-positive astrocytes were also observed in control cases, in diffuse Lewy body disease, in Creutzfeldt-Jacob disease, in HIV encephalitis and around cerebral infarcts. Tumoral astrocytes in pilocytic astrocytoma and in glioblastoma were also strongly APC positive. APC was not detected in cultured astroglial cells. These results indicate that APC expression is upregulated in astrocytes following their activation by several types of pathological insults and is a newly identified molecular characteristic of the reactive phenotype of astrocytes, possibly related to the control of cell proliferation. In addition, it also suggests that Abeta, and/or the inflammatory process associated with Abeta deposits, is responsible for a preferential increase of APC expression in astrocytes in AD.

Adenomatous Polyposis Coli Protein↗
PubMed2001

Biliary cholesterol hypersecretion in gallstone-susceptible mice is associated with hepatic up-regulation of the high-density lipoprotein receptor SRBI.

Enhanced hepatocellular trafficking of cholesterol to the bile canaliculus and cholesterol hypersecretion appears critical for gallstone formation. Therefore, we studied in more detail the hepatic cholesterol transport pathways in a mouse model of cholesterol gallstone disease. Biliary lipid secretion rates, plasma lipoprotein levels, hepatic expression of lipoprotein receptors, lipid regulatory enzymes, and putative cholesterol transporting proteins were analyzed in gallstone-susceptible C57L/J and gallstone-resistant AKR/J mice, which were fed a lithogenic diet. Biliary cholesterol hypersecretion in C57L mice was associated with decreased plasma high-density lipoprotein (HDL) cholesterol levels and significant hepatic induction of the HDL receptor (SRBI) and cholesteryl ester hydrolase. In response to the lithogenic diet, fatty-acid binding protein of liver (FABPL) was markedly induced in both mouse strains. Caveolin 1 was elevated only in plasma membranes of gallstone-susceptible C57L mice, which also failed to down-regulate cholesterol synthesis. These data suggest a role of the reverse cholesterol transport pathway for genetically determined gallstone susceptibility in the mouse.

Animals↗
PubMed2001

[Is mini-screw osteosynthesis a suitable procedure in surgical treatment of intra-articular distal phalanx fractures?].

In a retrospective clinical study, the results of operative treatment of intraarticular fractures of the distal phalanx were studied. From February 1992 to December 1998, 75 patients were treated operatively, 47 were examined. 14 patients were treated with Lengemann wire and temporary transfixation of the DIP joint, 25 patients were treated with screw fixation and in eight patients another procedure (wire suture, Kirschner wire, "Hakendraht", combination of screw and wire) was used. All patients had little or no pain. All patients had no or only little limitation in activities of daily living. Two patients after screw fixation had serious limitations. Four patients after Lengemann wire fixation had an extension lag in the DIP joint of up to 10 degrees, four patients between 11 and 20 degrees and one patient 25 degrees. 19 patients after screw fixation had an extension lag of the DIP joint of up to 10 degrees, five patients between 11 and 20 degrees and one patient of 25 degrees. Arthrosis of the DIP joint was seen in five patients after Lengemann wire fixation and in two patients after screw fixation. Screw fixation in the treatment of intraarticular fractures of the distal phalanx is a good, but demanding procedure with the potential for exact reconstruction of the joint surface, since implant removal is not necessary.

Bone Screws↗
PubMed2001

Clustering of childhood mortality in rural Burkina Faso.

BACKGROUND: Childhood mortality is a major public health problem in sub-Saharan Africa. For the implementation of efficient public health systems, knowledge of the spatial distribution of mortality is required. METHODS: Data from a demographic surveillance research project were analysed which comprised information obtained for about 30 000 individuals from 39 villages in northwest Burkina Faso (West Africa) in the period 1993--1998. Total childhood mortality rates were calculated and the geographical distribution of total childhood mortality was investigated. In addition, data from a cohort of 686 children sampled from 16/39 of the villages followed up during a randomized controlled trial in 1999 were also used to validate the results from the surveillance data. A spatial scan statistic was used to test for clusters of total childhood mortality in both space and time. RESULTS: Several statistically significant clusters of higher childhood mortality rates comprising different sets of villages were identified; one specific village was consistently identified in both study populations indicating non-random distribution of childhood mortality. Potential risk factors which were available in the database (ethnicity, religion, distance to nearest health centre) did not explain the spatial pattern. CONCLUSION: The findings indicate non-random clustering of total childhood mortality in the study area. The study may be regarded as a first step in prioritizing areas for follow-up public health efforts.

Burkina Faso↗
PubMed2000

Substrate dependent differences in morphology and elasticity of living osteoblasts investigated by atomic force microscopy.

We have used the atomic force microscope (AFM) as a tool for testing the biocompatibility of implant materials by investigating the adhesion behavior of osteoblast cells in vitro. This technique allowed the investigation of cytomorphology and cytomechanical properties of living cells on a submicrometer scale. Cell adhesion was investigated on Cobalt-Chromium (CoCr), Titanium (Ti) and Titanium-Vanadium (TiV) substrates, which are of great interest in the field of implant research. The elastic properties and the morphology of living osteoblasts on the metallic substrates were compared with those of osteoblasts cultured on glass and tissue culture polystyrene (PS). Furthermore, a characterization of the surface roughness of the substrates was performed and the surface coverage of proteins after incubation with cell culture medium on the substrates was observed with the AFM.

Journal Article↗
PubMed2000

Seven genes that are differentially transcribed in colorectal tumor cell lines.

To identify genes which are differentially transcribed in colorectal tumor cells, we compared the two human tumor cell lines, SW480 and HCT116, with the cell line, NCM460, from normal colon epithelium as a control. Using the methods of differential display reverse transcription PCR and Northern blot hybridization, we detected the differential transcription of seven genes: cholecystokinin, reticulocalbin, Rab5 guanine nucleotide exchange factor Rabex5, caldesmon, differentiation related gene 1 (drg1), taxol resistant associated gene 3 (Trag-3) and the gene for the placental protein, diff33. The yet unidentified cDNA of the human Rabex5 gene and the 3' untranslated region of the human caldesmon gene were cloned.

Amino Acid Sequence↗
PubMed2000

Autophagic tubes: vacuolar invaginations involved in lateral membrane sorting and inverse vesicle budding.

Many intracellular compartments of eukaryotic cells do not adopt a spherical shape, which would be expected in the absence of mechanisms organizing their structure. However, little is known about the principles determining the shape of organelles. We have observed very defined structural changes of vacuoles, the lysosome equivalents of yeast. The vacuolar membrane can form a large tubular invagination from which vesicles bud off into the lumen of the organelle. Formation of the tube is regulated via the Apg/Aut pathway. Its lumen is continuous with the cytosol, making this inverse budding reaction equivalent to microautophagocytosis. The tube is highly dynamic, often branched, and defined by a sharp kink of the vacuolar membrane at the site of invagination. The tube is formed by vacuoles in an autonomous fashion. It persists after vacuole isolation and, therefore, is independent of surrounding cytoskeleton. There is a striking lateral heterogeneity along the tube, with a high density of transmembrane particles at the base and a smooth zone devoid of transmembrane particles at the tip where budding occurs. We postulate a lateral sorting mechanism along the tube that mediates a depletion of large transmembrane proteins at the tip and results in the inverse budding of lipid-rich vesicles into the lumen of the organelle.

Cytoskeleton↗
PubMed2000

The Adenomatous Polyposis Coli-protein (APC) interacts with the protein tyrosine phosphatase PTP-BL via an alternatively spliced PDZ domain.

Mutations of the tumor suppressor protein APC (Adenomatous Polyposis Coli) are linked to familiar and sporadic human colon cancer. Here we describe a novel interaction between the APC protein and the protein tyrosine phosphatase PTP-BL carrying five PDZ protein-protein interaction domains. Exclusively, the second PDZ domain (PDZ2) of PTP-BL is binding to the extreme C-terminus of the APC protein, as determined by yeast two-hybrid studies. Using surface plasmon resonance analysis we established a dissociation constant (K(D)) of 8.1 x 10(-9) M. We find that a naturally occurring splice insertion of five amino acids (PDZ2b) abolishes its binding affinity to the APC protein. The in vivo interaction between PTP-BL and the APC protein was shown by coprecipitation experiments in transfected COS cells. Furthermore, in cultured epithelial Madine Carnine Kidney cells the subcellular colocalization was demonstrated for the nucleus and also for the tips of cellular extensions. The interaction of the APC protein with a protein tyrosine phosphatase may indirectly modulate the steady state levels of tyrosine phosphorylations of associated proteins, such as beta-catenin playing a major role in the regulation of cell division, migration and cell adhesion.

Adenomatous Polyposis Coli Protein↗
PubMed2000

[Traumatic sternoclavicular instability. A therapeutic alternative].

Traumatic instability of the sternoclavicular joint is a rare diagnosis. It is usually treated by different bandaging techniques without the possibility of early functional aftercare. In the period between 1 January 1996 and 31 December 1998, a total of eight patients with unstable sternoclavicular joints requiring surgical treatment were treated with Balser plates. The population comprised seven anterior and one posterior dislocations. The results achieved with this alternative treatment option, which offers the advantage of enabling early functional aftercare, are presented. Seven of eight patients were available for follow-up. The eighth patient moved from the area. The Constant Score ranged between 84 and 100 points (average 89 +/- 6.6).

Adolescent↗
PubMed2000

Transgenic rat hearts expressing a human cardiac troponin T deletion reveal diastolic dysfunction and ventricular arrhythmias.

OBJECTIVE: Familial hypertrophic cardiomyopathy (FHC) due to mutations of cardiac troponin T (cTnT) is associated with a high frequency of sudden death even in the absence of cardiac hypertrophy. To investigate the causal relationship of cTnT mutations and this particular phenotype, we sought to establish a transgenic rat model for the disease. METHODS: Transgenic rats were generated expressing human wild-type cTnT or two truncated cTnT molecules (del ex16, del ex15/16), resulting from an intron 15 splice donor site mutation previously observed in FHC patients. Transgenic rat hearts were characterized by histology, immunohistochemistry and in the 'working heart'. RESULTS: Human wild-type and del ex16 cTnT were stably expressed and incorporated into the sarcomere of transgenic cardiomyocytes. Del ex16 transgenic rats revealed a lower level of expression (4-5%) than human wt cTnT animals (25-40%). In the 'working heart' model del ex16 hearts exhibited significant systolic and diastolic dysfunction without cardiac hypertrophy. In contrast, human wt cTnT hearts showed improved contractile performance and moderate myocardial hypertrophy. After 6 months of daily physical exercise one del ex16 rat died suddenly and three out of five del ex16 hearts revealed ventricular tachycardia/fibrillation. No arrhythmia was observed in human wt cTnT expressors. Myofibrillar disarray was present in del ex16 hearts after training but not in human wild-type cTnT rats or non-transgenic controls. CONCLUSION: A human cTnT deletion overexpressed in transgenic rats exerts a dominant-negative effect and mimics the phenotype of FHC with diastolic dysfunction and arrhythmias. By contrast, human cTnT wild-type animals reveal a gain of function and cardiac hypertrophy without arrhythmias.

Animals↗