Search PubMed⌕ Search

Biomedical subjects

C Müller

Publications and source records attributed to C Müller.

At least 181 records · Page 10Linked to original sources
PubMed1999

Comparison of turbulent-flow chromatography with automated solid-phase extraction in 96-well plates and liquid-liquid extraction used as plasma sample preparation techniques for liquid chromatography-tandem mass spectrometry.

Turbulent flow chromatography (TFC) combined with the high selectivity and sensitivity of tandem mass spectrometry (MS-MS) is a new technique for the fast direct analysis of drugs from crude plasma. TFC in the 96-well plate format reduces significantly the time required for sample clean-up in the laboratory. For example, for 100 samples the workload for a technician is reduced from about 8 h by a manual liquid-liquid extraction (LLE) assay to about 1 h in the case of TFC. Sample clean-up and analysis are performed on-line on the same column. Similar chromatographic performance and validation results were achieved using HTLC Turbo-C18 columns (Cohesive Technologies) and Oasis HLB extraction columns (Waters). One 96-well plate with 96 plasma samples is analyzed within 5.25 h, corresponding to 3.3 min per sample. Compared to this LLE and analysis of 96 samples takes about 16 h. Two structurally different and highly protein bound compounds, drug A and drug B, were analyzed under identical TFC conditions and the assays were fully validated for the application to toxicokinetics studies (compliant with Good Laboratory Practices-GLP). The limit of quantitation was 1.00 microg/l and the linear working range covered three orders of magnitude for both drugs. In the case of drug A the quality of analysis by TFC was similar to the reference LLE assay and slightly better than automated solid-phase extraction in 96-well plates. The accuracy was -3.1 to 6.7% and the precision was 3.1 to 6.8% in the case of drug A determined for dog plasma by TFC-MS-MS. For drug B the accuracy was -3.7 to 3.5% and the precision was 1.6 to 5.4% for rat plasma, which is even slightly better than what was achieved with the validated protein precipitation assay.

Animals↗
PubMed1999

Cloning and heterologous expression of a cDNA encoding 1-deoxy-D-xylulose-5-phosphate reductoisomerase of Arabidopsis thaliana.

Various plant isoprenoids are synthesized via the non-mevalonate pathway of isopentenyl diphosphate formation. In this pathway, 1-deoxy-D-xylulose 5-phosphate (DOXP), the first intermediate, is transformed to 2-C-methyl-D-erythritol 4-phosphate (MEP) by an enzyme which was recently cloned from Escherichia coli. In order to find a plant homologue of this 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) we cloned a cDNA fragment from Arabidopsis thaliana which has high homology to the E. coli DXR. By expression of this fragment in E. coli we could demonstrate that it encodes a protein which transforms DOXP to MEP. The antibiotic fosmidomycin specifically inhibits this DXR enzyme activity.

Aldose-Ketose Isomerases↗
PubMed1999

Optimization of the immunosuppressive protocol after lung transplantation.

BACKGROUND: The successful use of tacrolimus (Tac)-based immunosuppressive therapy in organ transplantation and our own positive experience in heart transplantation led us to investigate regimens including this agent at our center for lung transplantation. METHODS: From 1991 to 1998, 86 patients underwent lung transplants at our center and 78 of them were included in this analysis. The first 34 patients were treated with cyclosporin (CsA), azathioprine (Aza), and rabbit antilymphocyte globulin; the subsequent 30 patients received Tac with Aza, and the most recent 12 patients Tac with mycophenolate mofetil (MMF). In addition, all patients received prednisone. RESULTS: The number of acute rejection episodes per 100 patient days was 1.5, 0.6, and 0.3 for three treatment groups, respectively. Similarly, the incidence of refractory acute rejection per 100 patient days was lower in both Tac groups (0.20, 0.03, and 0, respectively). Freedom from acute rejection was highest in the Tac-MMF group (P=0.0037 vs. Tac/Aza, P=0.0007 vs. CsA/Aza). Freedom from recurrent acute rejection was significantly higher in both Tac groups (P=0.027 Tac/ Aza vs. CsA/Aza and P=0.025 Tac/MMF vs. CsA/Aza). The incidence of infections per 100 patient days was similar (0.8, 0.5, and 0.8) in all three treatment groups, with a similar distribution of fungal, bacterial, and viral infections. Freedom from infection also showed no difference. The survival rate was significantly higher for the Tac population, with actuarial 1- and 3-year survival rates of 93% and 71%, compared with the CsA group (71% and 51%, respectively, P=0.04). Prevalence of renal dysfunction (creatinine >2.0 mg/ dL) was 18%, 13%, and 0% in the 3 treatment groups, respectively. The development of glucose metabolism disorders was lower in the CsA group than in the Tac-Aza group (15% vs. 27%, P<0.05). CONCLUSIONS: Tac-based immunosuppressive therapy results in a lower rate of acute rejection after pulmonary transplantation, with similar infection rates and a slightly higher incidence of new onset diabetes mellitus compared with CsA-based therapy.

Acute Disease↗
PubMed1999

Separation of C/EBPalpha-mediated proliferation arrest and differentiation pathways.

Cell proliferation and terminal differentiation are mutually exclusive in most cell lineages. The b-zip transcription factor CCAAT/enhancer-binding protein alpha (C/EBPalpha) induces proliferation arrest and differentiation in many cell types, suggesting that both activities are linked. Here we show that C/EBPalpha-mediated proliferation arrest and differentiation pathways can be separated by the E7 oncoprotein of the "high-risk" human papilloma virus 16. The E7 oncoprotein overrides C/EBPalpha-mediated cell cycle withdrawal without compromising the transactivation activity of C/EBPalpha or its ability to participate in differentiation. Uncoupling of both pathways depends on the casein kinase II site of the oncoprotein but not on its ability to neutralize pocket proteins or the cyclin-dependent kinase inhibitor protein p21. Our results suggest a bifurcation of C/EBPalpha-mediated proliferation arrest and differentiation pathways.

Animals↗
PubMed1999

The hepatitis alphabet--hepatitis A-G and TTV.

During the past three decades the number of viruses known to be capable to inducing liver inflammation has been considerably expanded. This short review gives a quick overview of the virologic characteristics, clinical manifestations, diagnosis, and treatment options. Newer hepatitis viruses such as hepatitis E virus (HEV), hepatitis GB-virus C/hepatitis G virus (GBV-C/HGV), and transfusion-transmitted virus (TTV) are discussed and data concerning their disease-inducing capacity reviewed.

Animals↗
PubMed1999

C/EBPepsilon directly interacts with the DNA binding domain of c-myb and cooperatively activates transcription of myeloid promoters.

C/EBPepsilon is essential for granulocytic differentiation. We investigated the role of C/EBPepsilon in the transcriptional activation of various myeloid-specific genes. We found that two C/EBPepsilon isoforms, p32 and p30, possessing transcriptional activation domains were coexpressed in myeloid cells. Interestingly, isoform C/EBPepsilon p30 but not p32 was differentially upregulated in NB-4 promyelocytic leukemia cells treated with retinoids. Both isoforms bound specifically to C/EBP sites in myeloid promoters. The kd for C/EBPepsilon binding to the C/EBP site of the neutrophil elastase promoter was 4.2 nmol/L. In transfection assays using the nonhematopoietic cell line, CV-1, the p32 isoform activated promoters from the myeloid-specific mim-1, neutrophil elastase, and granulocyte colony-stimulating factor (G-CSF) receptor genes by 2.5-, 1.8-, and 1.6-fold, respectively. The p30 isoform lacked significant transcriptional activity, suggesting that other hematopoietic-specific factors were required for its function. Consistent with this prediction, transfections into the hematopoietic cell line Jurkat showed a 9.0- and 2.5-fold activation of the mim-1 promoter by the p32 and p30 isoforms, respectively. The additional 32 NH2-terminal residues made p32 a significantly more potent transcriptional activator than p30. T lymphoblasts (Jurkat cells) and immature myeloid cells (eg, Kcl22 cells) expressed high levels of the c-myb hematopoietic transcription factor. Cotransfection of c-myb with either the p32 or p30 isoform of C/EBPepsilon in CV-1 cells cooperatively transactivated the mim-1 promoter by 20- and 16-fold, respectively, and the neutrophil elastase promoter by 10-and 7-fold, respectively. Pulldown assays showed that each C/EBPepsilon isoform interacted directly with the DNA binding domain of the c-myb protein. Further studies showed that Kcl22 myeloid cells only contained active C/EBPepsilon, but not C/EBPalpha, C/EBPbeta, or C/EBPdelta. A mutation of the C/EBP site in the neutrophil elastase promoter markedly decreased the transactivation of the promoter in Kcl22 myeloblasts. These results demonstrate a role for C/EBPepsilon in regulating myeloid promoters, such as neutrophil elastase, probably through a direct interaction with c-myb.

Animals↗
PubMed1999

Hepatopulmonary syndrome.

The hepatopulmonary syndrome (HPS) is a rare complication of liver cirrhosis and is characterised by the typical triad of liver cirrhosis, arterial hypoxemia, and intrapulmonary vascular dilatation. Except for pleural effusions associated with liver cirrhosis no other disease of the lungs or the heart is detectable. The structural hallmark of HPS is dilatation of pulmonary precapillary vessels which impairs diffusion-perfusion and causes unequal ventilation-perfusion. The diagnosis of HPS is based on PaO2 measurements when breathing room air and 100% oxygen. The increased intrapulmonary vascular diameter allows microbubbles to traverse the lung capillaries when agitated saline is administered intravenously. Only on rare occasions is a patient limited by his pulmonary impairment, the leading morbidity is that of liver disease and its classical complications. Drug therapy is of no proven benefit, oxygen supplementation might improve dyspnea. Vascular embolisation of discrete arteriovenous shunts, if present, or liver transplantation may dramatically improve pulmonary function in selected patients.

Arteriovenous Fistula↗
PubMed1999

Cloning of the cyclin A1 genomic structure and characterization of the promoter region. GC boxes are essential for cell cycle-regulated transcription of the cyclin A1 gene.

Cyclin A1 is a recently cloned cyclin with high level expression in meiotic cells in the testis. However, it is also frequently expressed at high levels in acute myeloid leukemia. To elucidate the regulation of cyclin A1 gene expression, we cloned and analyzed the genomic structure of cyclin A1. It consists of 9 exons within 13 kilobase pairs. The TATA-less promoter initiates transcription from several start sites with the majority of transcripts beginning within a 4-base pair stretch. A construct containing a fragment from -190 to +145 showed the highest transcriptional activity. Transfection of cyclin A1 promoter constructs into S2 Drosophila cells demonstrated that Sp1 is essential for the activity of the promoter. Sp1, as well as Sp3, bound to four GC boxes between nucleotides -130 and -80 as observed by gel shift analysis. Mutations in two or more of the four GC boxes decreased promoter activity by >80%. The promoter was found to be cell cycle-regulated with highest activities found in late S and G2/M phase. Further analyses suggested that cell cycle regulation was accomplished by periodic repression of the GC boxes in G1 phase. Taken together, our data show that cyclin A1 promoter activity critically depends on four GC boxes, and members of the Sp1 family appear to be involved in directing expression of cyclin A1 in both a tissue- and cell cycle-specific manner.

Base Sequence↗
PubMed1999

Cyclin A1 expression in leukemia and normal hematopoietic cells.

Human cyclin A1 is a newly cloned, tissue-specific cyclin that is prominently expressed in normal testis. In this study, we showed that cyclin A1 was highly expressed in a subset of leukemia samples from patients. The highest frequency of cyclin A1 overexpression was observed in acute myelocytic leukemias, especially those that were at the promyelocyte (M3) and myeloblast (M2) stages of development. Cyclin A1 expression was also detected in normal CD34(+) progenitor cells. The expression of cyclin A1 increased when these cells were stimulated to undergo myeloid differentiation in vitro. Taken together, our observations suggest that cyclin A1 may have a role in hematopoiesis. High levels of cyclin A1 expression are especially associated with certain leukemias blocked at the myeloblast and promyelocyte stages of differentiation.

Antigens, CD34↗
PubMed1999

Ultrastructure of glutamate and GABA immunoreactive axon terminals of the rat nucleus tractus solitarius, with a note on infralimbic cortex afferents.

The principal fast neurotransmitters in the CNS are glutamate and GABA. Our aim was to provide a baseline account on the ultrastructure of the axon terminals immunoreactive to glutamate or GABA present in the nucleus tractus solitarius (NTS) of the rat. In addition, we wanted to complete our study of cortico-solitary afferents at the electron microscopic level, by analyzing the inputs from the infralimbic cortex. Using post-embedding immunogold, we found that nearly 61% of the axon terminals were glutamatergic, and 36% were GABAergic in the rat visceral NTS. In general, axons making asymmetric synaptic contacts were enriched in glutamate, compared to axons involved in symmetric synapses. In contrast, the vast majority of the GABAergic axon terminals made symmetric synaptic contacts. We could discern five types of glutamatergic and two types of GABAergic axon terminals that differed in their fine structure. Afferents from the infralimbic cortex were small, with clear synaptic vesicles and no dense core vesicles; they made asymmetric contacts with fine dendrites, and were glutamatergic. We conclude that most axon terminals in the NTS use glutamate or GABA as fast transmitters, in addition to being a heterogeneous population of morphological types.

Animals↗
PubMed1999

Identification and characterisation of IS1383, a new insertion sequence isolated from Pseudomonas putida strain H.

A new insertion sequence (IS1383) was identified on plasmids from Pseudomonas putida strain H and its nucleotide sequence was determined. IS1383 contains perfect terminal inverted repeats of 13-bp flanking a 1.4-kb internal sequence. A single significant open reading frame was identified that can encode a 342-amino acid polypeptide which was predicted to be highly basic and to have homology to polypeptides known from several other bacterial insertion sequences. At least six copies of IS1383 are present on the plasmids pPGH1 and pPGH2, whereas no copy could be detected on the chromosome of P. putida strain H. Target duplications did not flank the inverted repeats of any of the six IS1383 copies examined. Analysis of the integration sites of IS1383 revealed hints for a target specificity. Multiple sequence alignments of the transposases, the inverted repeats and the integration sites pointed to the assignment of IS1383 into a putative new family of insertion sequences defined as the IS1111 family.

Amino Acid Sequence↗
PubMed1999

Prenatal diagnosis in a family with severe type I plasminogen deficiency, ligneous conjunctivitis and congenital hydrocephalus.

Severe type I plasminogen deficiency may cause severe ligneous conjunctivitis, a rare and unusual form of chronic pseudo-membranous conjunctivitis that usually starts in early infancy, but also pseudo-membranous lesions of other mucous membranes in the mouth, nasopharynx, trachea and female genital tract, and in rare cases congenital occlusive hydrocephalus. The index patient, the daughter of a consanguineous marriage, had suffered from severe ligneous conjunctivitis and had died from decompensated congenital hydrocephalus despite numerous shunt revisions. She was found to be homozygous for a non-sense mutation in exon 15 of the plasminogen gene (Trp597->Stop). In her next pregnancy, the mother asked for prenatal diagnosis of the plasminogen deficiency. Chorionic villus biopsy was performed at 12 weeks of gestation. DNA analysis of the plasminogen gene by PCR and single-strand conformation polymorphism (SSCP) revealed that the fetus exhibited an identical heterozygous band pattern as observed in the healthy mother. Therefore, the fetus was heterozygous for the Trp597->Stop mutation in plasminogen exon 15. In addition, the fetus was found to be male by cytogenetic analysis and by multiplex PCR analysis using two polymorphic X-chromosomal markers (DXS424, HPRT). These findings excluded the possibility of contamination by maternal DNA. It was concluded that the fetus was not at risk for ligneous conjunctivitis and its associated complications. After the birth of a healthy boy, plasminogen functional activity was shown to be 38 per cent. DNA analysis confirmed prenatal molecular genetic results.

Adult↗
PubMed1999

13-HPODE and 13-HODE modulate cytokine-induced expression of endothelial cell adhesion molecules differently.

Expression of cellular adhesion molecules (CAMs) at endothelial surfaces represents a physiological response to vascular damage and mediates the initiation of inflammation and possibly of atherogenesis. The cytokines TNF alpha and IL-1 are potent inducers of CAMs in endothelial cells. Reactive oxygen species comprising lipid oxidation products have been implicated in the signaling pathways of both TNF alpha and IL-1 and accordingly could modulate atherogenic events. We, therefore, investigated the potential role of the lipoxygenase product, 13-hydroperoxyoctadecadienoic acid (13-HPODE), which has also been identified in oxidized low density lipoproteins on CAM expression in HUVEC. 13-HPODE induced the expression of ICAM-1 in a concentration dependent manner up to 75 microM. Higher concentrations were toxic. Similar effects were observed with H2O2 and phosphatidylcholine hydroperoxide. VCAM-1 and E-selectin were not induced by 13-HPODE. 13-HPODE administered simultaneously with IL-1 or TNF alpha induced ICAM-1 additively, suggesting that hydroperoxides and cytokines act on the same signaling pathways. In contrast, pretreatment of cells with 50 microM 13-HPODE for 1 hour rather inhibited subsequent cytokine-induced ICAM-1 and E-selectin expression. Surprisingly, the reduction product of 13-HPODE, 13-hydroxyoctadecadienoic acid (13-HODE) proved to be an even better inducer of ICAM-1 than 13-HPODE. Pretreatment with 13-HODE did not show any inhibitory effect on ICAM-1 expression. Our data show that lipoxygenase products differentially affect CAM expression. 13-HPODE is stimulatory by itself and can positively or negatively affect cytokine signaling depending on time of exposure. 13-HODE induces CAM expression by itself but does not inhibit cytokine signaling. Thus, the interplay of lipoxygenase products with proinflammatory cytokines can not simply be explained by an oxidant-mediated facilitation of cytokine signaling.

Cell Adhesion Molecules↗
PubMed1999

[Gamma-hydroxybutyrate for treatment of alcohol withdrawal syndrome in intensive care patients. A comparison between with two symptom-oriented therapeutic concepts].

UNLABELLED: Seeing as gamma-hydroxybutyrate (GHB) and benzodiazepines interact with the GABA-transmitter system, we investigated whether GHB can replace the conventional therapy, which uses benzodiazepines in the treatment of alcohol withdrawal syndrome in ICU settings. METHODS: 42 chronic alcoholics were included in this prospective and randomized study. Following the development of alcohol withdrawal syndrome, the patients were randomly allocated to the GHB or to the flunitrazepam group. In addition to this, clonidine was administered in order to treat autonomic signs of withdrawal. In cases were hallucinations occurred, haloperidol was administered. RESULTS: There was no significant difference in the efficacy of treatment used in the duration of mechanical ventilation and intensive care unit stay between groups. The patients in the GHB-group required significantly higher dosages of haloperidol and significantly lower dosages of clonidine. 14 out of 21 patients from the GHB-group developed hypernatriaemia and 15 out of 21 developed a metabolic alkalosis. CONCLUSIONS: Symptoms of the autonomic nervous system were more effectively prevented by GHB as evident in the lower dosage requirement of clonidine. However, GHB may not sufficiently block the hyperactivity of the dopaminergic system or may have an hallucinogenic effect itself. This may be evident from the higher dosages of haloperidol which were necessary. Due to the latter fact, the administration of GHB cannot be recommended in all patients suffering from AWS in ICU settings.

Adrenergic alpha-Agonists↗
PubMed1999

[Distribution pattern and involvement of regional lymph nodes in non-small-cell bronchial carcinoma].

Despite the important role of lymph node infiltration for the classification and prognosis of non-small-cell lung cancer (NSCLC), no standards exist to evaluate the quality of mediastinal lymphadenectomy. Researches at several centers are not convinced that complete ipsilateral lymphadenectomy is necessary. We investigated 270 consecutive patients undergoing a potential curative operation for NSCLC including complete ipsilateral lymph node dissection in order to ascertain whether or not there is a correlation between tumor localization and lymph node infiltration. Patients were classified into the UICC (1987) stages I (n = 115), II (n = 42), and IIIa (n = 113). In patients with N1-positive lymph nodes (n = 61) we found higher 5-year survival for patients with only intrapulmonary lymph node infiltration (39%) than for patients with hilar infiltration (21%). Patients with N2 disease showed skip metastases in up to 81% of cases. We found that no tumor location predicted the lymph node infiltration. Due to the variability of lymph node infiltration and the frequently occurring skip metastases, complete ipsilateral lymphadenectomy should be the standard for curative operations for NSCLC.

Aged↗
PubMed1999

[Use of pedicled greater omentum-plasty as thoraco-abdominal defect repair following extensive tumor resection].

Patients suffering from long-untreated malignomas of the chest or abdominal wall may require plastic surgery due to extensive defects after tumor resection. Despite a variety of pedicled or free myocutaneous flaps, there are defects in which these reconstructional options may not be indicated. In these patients, the omental flaps are a valid alternative. Since a secondary split skin graft is mandatory with the omentum flap, antibacterial and granulation-enhancing xerodressings are required for wound bed conditioning. We report one patient in whom the omentum flap was used for coverage of an extensive defect after resection of a widespread basal cell carcinoma at the lateral thorax and abdominal wall. After wound conditioning with silver-impregnated activated charcoal xerodressing (Actisorb) in combination with a hydroactive polymer dressing (Allevyn), secondary skin grafting was performed. In this patient fibrosis and calcification of the omentum led to stable abdominal wall coverage even without the application of a synthetic mesh.

Abdominal Neoplasms↗