Biomedical subjects

R Müller

Publications and source records attributed to R Müller.

At least 127 records · Page 7Linked to original sources

PubMed2000

Bcl-2 independence of flavopiridol-induced apoptosis. Mitochondrial depolarization in the absence of cytochrome c release.

The new chemotherapeutic agent, flavopiridol, presently in clinical trials, has been extensively studied yet little is known about its mechanism of action. In this study we show that the induction of apoptosis by flavopiridol is largely independent of Bcl-2. This is indicated by the observation that neither overexpression nor the antisense oligonucleotide-mediated down-regulation of Bcl-2 had any effect on flavopiridol-induced cell killing. Our results suggest that flavopiridol can induce apoptosis through different pathways of caspase activation with caspase 8 playing a pivotal role. In human lung carcinoma cells, which contain high levels of endogenous Bcl-2 and lack procaspase 8, flavopiridol treatment leads to mitochondrial depolarization in the absence of cytochrome c release, followed by the activation of caspase 3 and cell death. These results clearly differ from observations made with other anti-tumor drugs and might explain, at least in part, the unusual anti-tumor properties of flavopiridol.

Antineoplastic Agents↗

PubMed2000

Phenol/cresol degradation by the thermophilic Bacillus thermoglucosidasius A7: cloning and sequence analysis of five genes involved in the pathway.

Bacillus thermoglucosidasius A7 degraded phenol at 65 degrees C via the meta cleavage pathway. Five enzymes used in the metabolism of phenol were cloned from B. thermoglucosidasius A7 into pUC18. Nine open reading frames were present on the 8.1kb insert, six of which could be assigned a function in phenol degradation using database homologies and enzyme activities. The phenol hydroxylase is a two-component enzyme encoded by pheA1 and pheA2. The larger component (50kDa) has 49% amino acid identity with the 4-hydroxyphenylacetate hydroxylase of Escherichia coli, while the smaller component (19kDa) is most related (30% amino acid identity) to the styrene monoxygenase component B from Pseudomonas fluorescens. Both components were neccessary for activity. The catechol 2, 3-dioxygenase encoded by pheB has 45% amino acid identity with dmpB of Pseudomonas sp. CF600 and could be assigned to superfamily I, family 2 and a new subfamily of the Eltis and Bolin grouping. The 2-hydroxymuconic acid semialdehyde hydrolase (2HMSH), encoded by pheC, revealed the highest amino acid identity (36%) to the equivalent enzyme from Pseudomonas sp. strain CF600, encoded by dmpD. Based on sequence identity, pheD and pheE were deduced to encode the 2-hydroxypenta-2,4-dienoate hydratase (2HDH), demonstrating 45% amino acid identity to the gene product of cumE from Pseudomonas fluorescens and the acetaldehyde dehydrogenase (acylating) demonstrating 57% amino acid identity to the gene product of bphJ from Pseudomonas LB400.

Aldehyde Oxidoreductases↗

PubMed2000

IL-10, but not IL-4, suppresses infection-stimulated bone resorption in vivo.

Periapical bone resorption occurs following infection of the dental pulp and is mediated mainly by IL-1alpha in the murine model. The production and activity of IL-1alpha is modulated by a network of regulatory cytokines, including those produced by Th1 (pro-inflammatory) and Th2 (anti-inflammatory) subset T cells. This study was designed to assess the functional role of the Th2-type cytokines IL-4 and IL-10 in infection-stimulated bone resorption in vivo. The dental pulps of the first molars were exposed and infected with a mixture of four common endodontic pathogens, and bone destruction was determined by micro-computed tomography at sacrifice on day 21. The results demonstrate that IL-10(-/-) mice had significantly greater infection-stimulated bone resorption in vivo compared with wild-type mice (p < 0.001), whereas IL-4(-/-) exhibited no increased resorption. IL-10(-/-) had markedly elevated IL-1alpha production within periapical inflammatory tissues (>10-fold) compared with wild type (p < 0.01), whereas IL-4(-/-) exhibited decreased IL-1alpha production (p < 0.05). IL-10 also suppressed IL-1alpha production by macrophages in a dose-dependent fashion in vitro, whereas IL-4 had weak and variable effects. We conclude that IL-10, but not IL-4, is an important endogenous suppressor of infection-stimulated bone resorption in vivo, likely acting via inhibition of IL-1alpha expression.

Animals↗

PubMed2000

The serine and threonine residues in the Ig-alpha cytoplasmic tail negatively regulate immunoreceptor tyrosine-based activation motif-mediated signal transduction.

The B cell antigen receptor (BCR) is a multiprotein complex consisting of the membrane-bound Ig molecule and the Ig-alpha/Ig-beta heterodimer. On BCR engagement, Ig-alpha and Ig-beta become phosphorylated not only on tyrosine residues of the immunoreceptor tyrosine-based activation motif but also on serine and threonine residues. We have mutated all serine and threonine residues in the Ig-alpha tail to alanine and valine, respectively. The mutated Ig-alpha sequence was expressed either as a single-chain Fv/Ig-alpha molecule or in the context of the complete BCR. In both cases, the mutated Ig-alpha showed a stronger tyrosine phosphorylation than the wild-type Ig-alpha and initiated increased signaling on stimulation. These findings suggest that serine/threonine kinases can negatively regulate signal transduction from the BCR.

Adaptor Proteins, Signal Transducing↗

PubMed2000

In vivo structure of the cell cycle-regulated human cdc25C promoter.

The cdc25C promoter is regulated during the cell cycle by the transcriptional repressor CDF-1 that inhibits the activation function of upstream transcriptional activators, most notably the nuclear factor Y/CAAT box binding factor (NF-Y/CBF). In this report a detailed analysis of the in vivo structure of the cdc25C promoter was made. Micrococcus nuclease and methidiumpropyl-EDTA footprinting strongly suggest that the proximal promoter encompassing the cell cycle-dependent element/cell cycle genes homology region and the upstream NF-Y sites is organized in a positioned nucleosome throughout the cell cycle. Furthermore, structural perturbations were detected by DNase I, phenanthroline copper, and KMnO(4) footprinting at the NF-Y binding sites in vivo, which is in agreement with the reported property of NF-Y to bend DNA in vitro. Similar results were obtained with the structurally and functionally related cyclin A promoter. The structural perturbations seen in DNase I and phenanthroline copper footprints were less pronounced in G(0) cells when compared with cycling cells. This presumably reflects a weakened in vivo interaction of NF-Y with its cognate DNA element in G(0). It is likely that these structural perturbations, together with the reported ability of NF-Y to recruit histone acetyl transferase activity, contribute to an opened chromatin structure as a prerequisite for optimal regulation through activation and repression.

Base Sequence↗

PubMed2000

[Thrombotic thrombocytopenic purpura (Moschkowitz-syndrome) caused by ticlopidine].

BACKGROUND: Only in a few case reports the thrombotic thrombocytopenic purpura was related to ticlopidine with a controversial discussion about this association. CASE REPORT: In a 57-year-old female patient, who was admitted with fluctuating central neurological abnormalities and generalized purpura, was made the diagnosis of a thrombotic thrombocytopenic purpura (TTP, Moschcowitz' syndrome). On admission there were a distinct anemia and thrombocytopenia. Corresponding to the hemolysis the laboratory findings showed raised reticulocytes and elevated LDH with > 900 U/l. The peripheral blood smear showed an enrichment of fragmented red cells (15%) and the bone marrow indicated a hyperplastic erythrocytopoesis and a left shift in megakaryocytopoesis. An increase of eosinophilic granulocytes and the tissue basophilic cells directed to a possible allergic phenomenon of the underlying disease. Until 3 weeks before admission she had been on ticlopidine after a left heart catheter with stenting the left coronary artery 6 weeks earlier. Beside taking of acetylsalicylacid and thyroid hormone there was no other regular medication. An early treatment with fresh frozen plasma and plasmapheresis with plasma exchange with fresh frozen plasma led directly to an elevation of thrombocytes and a normalization of hemolytic parameters. CONCLUSION: This case demonstrates the possible relationship between thrombotic thrombocytopenic purpura and the administration of ticlopidine.

Female↗

PubMed2000

Synthesis and evaluation of hydroxylated polyamine analogues as antiproliferatives.

The synthesis of four hydroxylated polyamine analogues, (2R, 10R)-N(1),N(11)-diethyl-2,10-dihydroxynorspermine, (2S,10S)-N(1), N(11)-diethyl-2,10-dihydroxynorspermine, (3S,12S)-N(1), N(14)-diethyl-3,12-dihydroxyhomospermine, and (3R,12R)-N(1), N(14)-diethyl-3,12-dihydroxyhomospermine, is described along with their impact on the growth and polyamine metabolism of L1210 murine leukemia cells. Four different synthetic approaches are set forth, two each for the hydroxylated norspermines and for the hydroxylated homospermines. The key step in the assembly of the norspermines was the coupling of either N-[(2R)-2,3-epoxypropyl]-N-ethyl p-toluenesulfonamide or N-[(2S)-2,3-epoxypropyl]-N-ethyl trifluoromethanesulfonamide to N,N'-dibenzyl-1,3-diaminopropane. The key step with homospermines employed alkylation of putrescine with (3S)-N-(benzyloxycarbonyl)-N-ethyl-3,4-epoxybutylamine or of N, N'-bis(mesitylenesulfonyl)-1,4-butanediamine with (2R)-2-benzyloxy-4-[N-(mesitylenesulfonyl)ethylamino]-O-tosyl-1-++ +butan ol. All of the hydroxylated analogues were active against L1210 cells with 96-h IC(50) values of </=2 microM, and they also effectively reduced putrescine and spermidine, although the effect on spermine pools ranged from moderate to insignificant. Interestingly, the impact of the hydroxylated analogues on ornithine decarboxylase (ODC) was significantly less than that of unhydroxylated parent drug (e.g., N(1),N(11)-diethylnorspermine [DENSPM]) at 1 microM; however, S-adenosylmethionine decarboxylase (AdoMetDC) depletion was nearly identical to what was observed in cells treated with parent drug. The most notable difference between the parent and hydroxylated analogues was seen with spermidine/spermine N(1)-acetyltransferase (SSAT) upregulation in the DENSPM series. The hydroxylated analogues, especially (R, R)-(HO)(2)DENSPM, were much less effective at upregulation than the parent DENSPM. Finally, a comparison of the toxicity of (R, R)-(HO)(2)DENSPM with that of DENSPM at subchronic doses revealed that the neurological effects seen with DENSPM were now absent.

Animals↗

PubMed2000

[Objective measurement of normal nasality in the Saxony dialect].

In the United States of America, the nasometer was developed by Fletcher as an objective method for measuring nasality. There are no accepted normal values for comparable test materials regarding the German language. The aim of this study was the examination of the auditively normal nasality of Saxon-speaking people with the nasometer. The nasalance of 51 healthy Saxon-speaking test persons with auditively normal nasality was measured with a model 6200 nasometer (Kay-Elemetrics, U.S.A.). The text materials used were the vowels "a", "e", "i", "o", and "u", the sentences "Die Schokolade ist sehr lecker" ("The chocolate is very tasty") and "Nenne meine Mama Mimi" ("Name my mama Mimi"), and the texts of "North wind and sun", "A children's birthday", and an arbitrary selection from Strittmatter. The mean nasalance for the vowels was 17.7%, for the sentence containing no nasal sounds 13.0%, and for the sentence containing many nasal sounds 67.2%. The mean value of the texts was 33-41%. The results for the texts agreed well with the results of Reuter (1997), who examined people from the state of Brandenburg. A range from 20% to 55% is suggested as the normal value for nasalance in the German-speaking area.

Adolescent↗

PubMed2000

Hyperimmunoglobulin prophylaxis, monitoring and preemptive ganciclovir treatment eliminate the risk of CMV infection to improve patient and renal allograft survival.

This study was designed to investigate whether the introduction of ganciclovir to clinical use for anti-CMV treatment changes the risk of CMV infection in renal transplant patients. A total of 1545 cases who had received cadaveric renal transplants were divided into two groups: group 1 (n = 721) was made up of patients who received their transplants within 6 years before the introduction (1991) of ganciclovir and group 2 (n = 824), of individuals transplanted thereafter. Patient and graft survival of CMV D+/R- patients was uni- and multivariately compared with non-CMV D+/R- patients. In CMV D+/R- patients in group 1, survival was significantly lower, and their relative risk for graft loss was 1.32-fold (P = 0.0483) that of non-CMV D+/R- patients. In group 2 patient and graft survival was identical regardless of whether the patients were at risk for CMV infection or not. The risk of CMV infection can be eliminated by hyperimmunoglobulin prophylaxis, CMV monitoring and preemptive ganciclovir treatment in renal transplant patients.

Adult↗

PubMed2000

Identification of an L-dopa decarboxylase gene from Sorangium cellulosum So ce90.

During a screening program intended to identify genes encoding enzymes typical for secondary metabolism in Sorangium cellulosum So ce90, an aromatic amino acid decarboxylase gene (ddc) was detected. Expression of ddc in Escherichia coli and subsequent enzyme assays with cell-free extracts confirmed the proposed function derived from amino acid sequence comparisons. In contrast to other aromatic amino acid decarboxylases of eukaryotic origin, the S. cellulosum Ddc converted only L-dihydroxy phenylalanine. This is the first report of a gene encoding an L-dihydroxy phenylalanine decarboxylase in bacteria.

Amino Acid Sequence↗

PubMed2000

[Workload and health of older employees in service occupations].

Presented are the results of a representative survey of the German work force (N = 34,343) regarding work load and work-related diseases. The study comprises females and males aged 45 years and older, who are occupied in the service sector (N = 8310). The findings show that older workers in this economic sector have to bear considerable physical and mental work loads that are often higher than those for the total labor force. The results presented point to the need to encourage and practice a more comprehensive health promotion for older workers in the service sector.

Aged↗

PubMed2000

[Clinical experiences with the PercuSurge GuardWire--a new system for prevention of peripheral embolisms in catheter interventions on degenerated coronary artery venous bypasses].

Peripheral embolization is a typical complication of catheter interventions in degenerated aortocoronary saphenous vein grafts. Alternative techniques, such as transluminal extraction catheter (TEC), directional coronary athrectomy (DCA) and eximer laser angioplasty (ELCA) were not able to reduce the risk of peripheral vessel occlusion or "no-reflow". For the protection from peripheral embolisation we used the PercuSurge GuardWire Temporary Occlusion & Aspiration System (PercuSurge Inc., Sunnyvale, USA) in 55 patients with 58 stenosis in degenerated saphenous vein grafts. The primary endpoint of this consecutive series was to access the efficacy of the system by post-interventional TIMI flow and determination of serial CK/CK-MB. The intervention was primarily successful in 55 of 58 cases (94.8%), with a reduction in stenosis from 87.6% (range 75-100%) to 4.5% (range 0-40%). TIMI flow improved from a mean of 2.1 +/- 1.4 to 2.9 +/- 0.4 after intervention. CK/CK-MB levels were 24/5, 27/7 and 26/6 U/l (mean values) before, 8 hours, 16 hours and 24 hours after intervention, ruling out myocardial ischemia. Three (5.2%) non-q wave infarctions occurred in this series, twice caused by a peripheral embolization during the crossing of the lesion with the wire und once because of "no-reflow". In the latter case the occlusion balloon had to be deflated before the aspiration could be performed. In 80 of 92 aspirates (86.9%) macroscopic embolic debris was visible. The PercuSurge GuardWire Temporary Occlusion & Aspiration System is a safe and effective device for the protection of distal embolization during interventions in degenerated aorto-coronary saphenous vein grafts.

Adult↗

PubMed2000

Gene therapy: designer promoters for tumour targeting.

One of the biggest challenges facing cancer therapy is to generate tumour-specific treatment strategies. Gene therapy hopes to achieve this by directing the activity of therapeutic genes specifically to the sites of disease. Of paramount importance for the success of this approach is the availability of tumour-specific delivery systems: both the transductional targeting of the vector vehicle and the restriction of transgene expression to the tumour are promising strategies towards this goal. This review will focus on the recent achievements in the field of transcriptional targeting and the different strategies to improve or design promoters with the desired specificities.

Animals↗

PubMed2000

Early morphometric and anisotropic change in periarticular cancellous bone in a model of experimental knee osteoarthritis quantified using microcomputed tomography.

OBJECTIVE: To quantify early stage microstructural changes of periarticular cancellous bone in a canine anterior cruciate ligament transection model for experimental osteoarthritis. DESIGN: Unilateral transection of the anterior cruciate ligament was performed in 10 animals. Bone structure changes were quantified in five animals at 3-week post-transection and five animals at 12-week post-transection. An additional two non-operated animals were used as controls. BACKGROUND: Changes in trabecular architecture of the periarticular cancellous bone in early stage post-traumatic osteoarthritis is not well understood. Previous studies have found alterations in bone mineral density in experimental osteoarthritis suggesting adaptation of the trabecular structure. Early change of the periarticular bone following a ligament injury may contribute to the long-term development of osteoarthritis. METHODS: ++. Bone cores from the medial condyles of the femoral and tibial pairs were scanned with a three-dimensional microtomographic system. Structural indices were quantified including bone volume ratio, bone surface ratio, trabecular thickness, trabecular separation, trabecular number, as well as structural anisotropy determined by the mean-intercept-length method.Results. Significant structural changes were observed at 3-week post-transection, and were more prominent at 12-week post-transection. These changes were accompanied by decreasing anisotropy. CONCLUSIONS: Periarticular cancellous bone microstructure is significantly altered in experimental osteoarthritis. These changes occurred as early as 3-week post-transection, and were large at 12-week post-transection. RELEVANCE: The pathogenesis of post-traumatic osteoarthritis is poorly understood, but it is clear that this disease involves the entire organ system of the joint, including the cartilages, synovium, ligaments, and bones. This study focuses on the changes that occur in the bones during the early stages following a joint injury, and contributes to a better overall understanding of the disease aetiology.

Animals↗

PubMed2000

[Alcohol at the work site].

In Switzerland in large companies alcohol prevention programmes are wide spread. Their basic aim is to reduce hidden costs and to improve security at the workplace. To reach these goals early detection of employees with alcohol problems has been introduced and referral systems to therapeutic measures have been developed. Many of the alcohol prevention programmes, however, do not meet the standards of good practice discussed in this article. In addition, the cost efficiency of these programmes could rarely be proved. A noticeable lack of alcohol prevention programmes exists, however, in small and medium companies.

Alcohol Drinking↗

PubMed2000

Secreted human beta-glucuronidase: a novel tool for gene-directed enzyme prodrug therapy.

A major problem of tumor gene therapy is the low transduction efficiency of the currently available vectors. One way to circumvent this problem is the delivery of therapeutic genes encoding intracellular enzymes for the conversion of a prodrug to a cytotoxic drug which can then spread to neighboring non-transduced cells (bystander effect). One possibility to improve the bystander effect could be the extracellular conversion of a hydrophilic prodrug to a lipophilic, cell-permeable cytotoxic drug. Toward this end, we have used a secreted form of the normally lysosomal human beta-glucuronidase (s-betaGluc) to establish an extracellular cytotoxic effector system that converts an inactivated glucuronidated derivative of doxorubicin (HMR 1826) to the cytotoxic drug. We demonstrate that s-betaGluc-transduced tumor cells convert HMR 1826 to doxorubicin which is taken up by both transduced and non-transduced cells. s-betaGluc in combination with HMR 1826 efficiently induces tumor cell killing both in cell culture and in vivo. This effect is mediated through a pronounced bystander effect of the generated cytotoxic drug. Most notably, this gene therapeutic strategy is shown to be clearly superior to conventional chemotherapy with doxorubicin. Gene Therapy (2000) 7, 224-231.

Choriocarcinoma↗

PubMed2000

Endothelial-like cells derived from human CD14 positive monocytes.

In the present study, we show that endothelial-like cells (ELCs) can develop from human CD14-positive mononuclear cells (CD14 cells) in the presence of angiogenic growth factors. The CD14 cells became loosely adherent within 24 h of culture and subsequently underwent a distinct process of morphological transformation to caudated or oval cells with eccentric nuclei. After 1 week in culture the cells showed a clear expression of endothelial cell markers, including von Willebrand factor (vWF), CD144 (VE-cadherin), CD105 (endoglin), acetylated low-density lipoprotein (AC-LDL)-receptor, CD36 (thrombospondin receptor), FLT-1, which is vascular endothelial cell growth factor (VEGF) receptor-1, and, to a weaker extent, KDR (VEGF receptor-2). Furthermore, in these cells structures resembling Weibel-Palade bodies at different storage stages were identified by electron microscopy, and upon culturing on three-dimensional fibrin gels the cells build network-like structures. In addition, cell proliferation and vWF expression was stimulated by VEGF, and the endothelial cell adhesion molecules CD54 (ICAM-1), and CD106 (VCAM-1) became transiently inducible by tumor necrosis factor-alpha (TNF-alpha). In contrast, the dendritic markers CD1a, and CD83 were not expressed to any significant extent. The expression of CD68, CD80 (B7-1), CD86 (B7-2), HLA-DR and CD36 may also suggest that ELCs might be related to macrophages, sinus lining or microvascular endothelial cells. Taken together, our observations indicate that ELCs can differentiate from cells of the monocytic lineage, suggesting a closer relationship between the monocyte/macrophage- and the endothelial cell systems than previously supposed.

Antigens, Differentiation↗

PubMed2000

The myxochelin iron transport regulon of the myxobacterium Stigmatella aurantiaca Sg a15.

The biosynthetic gene cluster of the myxochelin-type iron chelator was cloned from Stigmatella aurantiaca Sg a15 and characterized. This catecholate siderophore was only known from two other myxobacteria. The biosynthetic genes of 2,3-dihydroxybenzoic acid are located in the cluster (mxcC-mxcF). Two molecules of 2, 3-dihydroxybenzoic acid are activated and condensed with lysine in a unique way by a protein homologous to nonribosomal peptide synthetases (MxcG). Inactivation of mxcG, which encodes an adenylation domain for lysine, results in a myxochelin negative mutant unable to grow under iron-limiting conditions. Growth could be restored by adding Fe3+, myxochelin A or B to the medium. Inactivation of mxcD leads to the same phenotype. A new type of reductive release from nonribosomal peptide synthetases of the 2, 3-dihydroxybenzoic acid bis-amide of lysine from MxcG, catalyzed by a protein domain with homology to NAD(P) binding sites, is discussed. The product of a gene, encoding a protein similar to glutamate-1-semialdehyde 2,1-aminomutases (mxcL), is assumed to transaminate the aldehyde that is proposed as an intermediate. Further genes encoding proteins homologous to typical iron utilization and iron uptake polypeptides are reported.

Amino Acid Sequence↗