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Biomedical subjects

M Oellerich

Publications and source records attributed to M Oellerich.

At least 37 records · Page 2Linked to original sources
PubMed2001

No influence of the MDR-1 C3435T polymorphism or a CYP3A4 promoter polymorphism (CYP3A4-V allele) on dose-adjusted cyclosporin A trough concentrations or rejection incidence in stable renal transplant recipients.

BACKGROUND: A substantial proportion of the variability in the absorption and clearance of cyclosporin A (CsA) after oral administration has been attributed to variability in liver cytochrome P-450 3A4 (CYP3A4) activity and intestinal P-glycoprotein (P-gp) concentration. A polymorphism in the CYP3A4 promoter region, termed "variant" allele CYP3A4-V, was postulated to be associated with altered CYP3A4 enzyme activity. A polymorphism in exon 26 (C3435T) of the multidrug resistance-1 (MDR-1) gene was correlated with intestinal expression and in vivo activity of P-gp. METHODS: We investigated the occurrence of both polymorphisms in 124 stable Caucasian renal transplant recipients (>6 months after transplantation) on CsA as the primary immunosuppressant. Real-time, rapid-cycle PCR methods were developed and used for genotyping. RESULTS: The estimated allele frequencies for the MDR-1 C3435T allele (54%) and the CYP3A4-V allele (4.8%) were similar to those reported for Caucasian populations. No significant differences were found for the CsA doses needed to maintain similar CsA trough concentrations in patients with and without the CYP3A4-V allele or in patients with different MDR-1 C3435T genotypes. Furthermore, neither of the polymorphisms investigated was associated with renal function as assessed by creatinine plasma concentration or, in a retrospective analysis, the incidence of acute rejection. CONCLUSIONS: These findings suggest that the MDR-1 C3435T mutation and the CYP3A4-V variant are not major determinants of CsA efficacy in renal transplant recipients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Prothrombin activity and concentration in healthy subjects with and without the prothrombin G20210A mutation.

A common mutation in the prothrombin gene (G20210A) is associated with elevated prothrombin levels and thrombosis. The pathomechanism related to the G20210A mutation is currently not understood and the interdependence of prothrombin activity and prothrombin concentration in plasma is still poorly defined. Six of 191 blood donors examined in the present study carried the prothrombin allele G20210A. Despite the small number of cases, plasma samples from these individuals had significantly higher prothrombin activities than wild type carriers, whereas their prothrombin concentrations-although elevated-did not differ significantly from wild type. In subjects with the G20210A mutation there was also no significant correlation between prothrombin activity and concentration. Analyzing data from healthy blood donors without the prothrombin G20210A mutation, we found only weak correlations between prothrombin activity and concentration of immunoreactive prothrombin. Samples with a relatively high prothrombin concentration but low activity were observed as well as samples with a relatively high activity for a given concentration (hyperactive prothrombin). F1+2 concentrations as indicators of activated coagulation were only elevated in 13 of 125 investigated samples and could not explain any of these findings. Dysfunctional variants of prothrombin, a well known phenomenon, may be responsible for the former, and we speculate that posttranscriptionally modified prothrombin species may explain the observed functional diversity of this factor including hyperactivity. The genotype-phenotype association of the non-coding G20210A mutation is not clear cut. Therefore, further studies are needed to determine which factors apart from the known G20210A polymorphism regulate prothrombin concentration and/or activity and may trigger the manifestation of thrombosis.

Adult↗
PubMed2000

Mycophenolate mofetil in stem cell transplant patients in relation to plasma level of active metabolite.

OBJECTIVES: To investigate mycophenolate mofetil (MMF) plasma levels and impact on acute graft versus host disease (aGvHD) after stem cell transplantation (SCT). METHODS: SCT patients (n = 14) with aGvHD (>/= II) receiving MMF (1-3 g/d) in addition to cyclosporine, prednisolone, and methotrexate for aGvHD prophylaxis were investigated. Plasma levels of mycophenolic acid (MPA) and its glucuronide metabolite (MPAG) were determined by high-performance liquid chromatography. RESULTS: Overall median steady state pre-dose plasma MPA concentration was 0.47 mg/L and increased within 75 min after administration to 1.64 mg/L. In comparison to patients with skin aGvHD, patients with gut aGvHD had lower MPA concentrations, both pre-dose (p = 0.16) and after 75 min, (p = 0.02). All 7 patients with skin aGvHD but only 2 patients with gut aGvHD responded to MMF. Overall, the pre-dose plasma MPA concentration was significantly (p = 0.007) greater in responders (n = 9) than in non-responders (n = 5). CONCLUSION: MMF seems to be an effective treatment for aGvHD in SCT patients particular in those patients without gut involvement.

Drug Therapy, Combination↗
PubMed2000

c-fos and c-jun mRNA expression in a pig liver model of ischemia/reperfusion: effect of extended cold storage and the antioxidant idebenone.

OBJECTIVES: Expression of immediate early genes has been reported during reperfusion after ischemia in rat livers due to oxygen radical formation. This study investigates in perfused pig livers the effect of the antioxidant idebenone and of cold ischemia time on the gene expression of c-fos and c-jun. DESIGN AND METHODS: Livers were perfused for 210 min after 0.5 h or 20 h ischemic storage (4 degrees C). One group of pigs was fed idebenone (280 mg/day/7days) prior to organ harvesting. C-fos and c-jun mRNA were determined by RT-PCR at 3, 30, 60, 120 180, 210 min during reperfusion. RESULTS: Lipid peroxidation increased in liver tissue form 0.54 +/- 0.21 to 1. 09 +/- 0.54 nmol MDA/mg protein during reperfusion after 20 h compared to 0.5 h cold storage. This was antagonized by idebenone (0. 68 +/- 0.20 nmol/MDA/mg protein). C-fos and c-jun were strongly induced in livers stored for 20 h, which was attenuated by idebenone (p < 0.05). CONCLUSIONS: These findings suggest that cold ischemia time and oxygen radicals are critical for immediate early gene expression and that application of an effective antioxidant can attenuate this early stress reaction of the pig liver.

Animals↗
PubMed2000

A method for homogeneous color-compensated genotyping of factor V (G1691A) and methylenetetrahydrofolate reductase (C677T) mutations using real-time multiplex fluorescence PCR.

OBJECTIVES: To set up an optimized multiplex polymerase chain reaction for real-time genotyping of the prothrombotic risk factors methylenetetrahydrofolate reductase C677T and factor V Leiden on the LightCycler. DESIGN AND METHODS: Novel primer and probe sets were designed on the basis of thermodynamic double-strand DNA stability calculations. Detection probes were labeled with LC-Red640 or Cy5.5 dye. RESULTS: The polymerase chain reaction efficiency was reduced in multiplex polymerase chain reaction but this could be overcome by the design of novel amplification primers. The selection of detection probes with a lower melting temperature (T(m)) and high Delta T(m) improved the discrimination of heterozygous samples. Color compensation was not compromised by either the use of the Cy5.5 dye or different fluorescein linker chemistries. CONCLUSIONS: Probes with a Delta T(m) of 5 degrees C or more between the matched and mismatched state are desirably for genotyping. Such probes can be selected by using a priori calculations based on the thermodynamic nearest neighbor model.

DNA Mutational Analysis↗
PubMed2000

Induction of cytokine release by the acyl glucuronide of mycophenolic acid: a link to side effects?

OBJECTIVES: We have identified an acyl glucuronide (M-2) of the immunosuppressant mycophenolic acid (MPA). Acyl glucuronides have toxic potential and may contribute to drug toxicity. Whether acyl glucuronides are able to induce release of proinflammatory cytokines is unknown. Gastrointestinal disturbances have been observed during MPA therapy and may involve an inflammatory reaction. This study investigated whether M-2 can induce IL-6 and TNF-alpha release as well as gene expression of these cytokines in leukocytes. DESIGN AND METHODS: M-2 was produced by incubation of MPA with human liver microsomes. Human mononuclear leukocytes were incubated in the presence of M-2. Concentrations of IL-6 and TNF-alpha were measured by ELISA. Expression of mRNA was determined by quantitative RT-PCR. RESULTS: Incubation of 3 x 10(6) cells with M-2 resulted in a time and dose dependent release of cytokines, whereas MPA or its phenolic glucuronide MPAG were without effect. Cytokine liberation depended on mRNA induction. Response to M-2 showed much inter individual variability (30-fold for IL-6, 3-fold for TNF-alpha). CONCLUSIONS: If M-2 promotes release of cytokines in vivo, these may mediate some of the toxic actions of MPA.

Adult↗
PubMed2000

Pharmacokinetic and metabolic investigations of mycophenolic acid in pediatric patients after renal transplantation: implications for therapeutic drug monitoring. German Study Group on Mycophenolate Mofetil Therapy in Pediatric Renal Transplant Recipients.

The need for mycophenolic acid (MPA) monitoring is still under discussion. Key issues for the PK/PD relationships of this drug are: the role of metabolites, the usefulness of AUC versus predose levels, and the need to monitor the free concentration of MPA (f-MPA). Recent advances have revealed that, in addition to 7-O-MPAG, three additional MPA metabolites are present in the plasma of transplant recipients. One of these metabolites (M-2), identified as an acyl glucuronide of MPA, was found to inhibit IMPDH-II in vitro. This active metabolite was also found to cross-react in the Emit assay for MPA. In an ongoing multicenter study, the authors are evaluating the relevance of monitoring total (t-MPA) and free mycophenolic acid (f-MPA) in pediatric renal transplant recipients. As in adults, a time-dependent increase of t-MPA-AUC(0-12h) within the first 3 months posttransplant (35 versus 64 mg x h/L, [corrected] 3 weeks versus 3 months respectively; daily dosage: 0.6 g/m2 bid) was seen. Receiver operating characteristics curve analyses were used to test the ability of predose levels or AUC(0-12h) to discriminate between cases with no complications and those with acute rejection, adverse events (severe infections, leukopenia), or gastrointestinal disorders observed during the early posttransplant course. In agreement with observations in adults, a significant (p = 0.001) association was observed between AUC(0-12h) and acute rejection. A t-MPA-AUC(0-12h) of approximately 30-60 mg x h/L [corrected], as determined by HPLC, seems to be a reasonable target for the early posttransplant period. It remains to be elucidated whether regular predose level monitoring may be of more practical value. A higher incidence of rejection was observed at predose MPA concentrations < or = 1 mg/L, as measured by HPLC. In contrast to t-MPA, f-MPA-AUC(0-12h) was significantly related to severe infections and leukopenia. The risk for severe adverse events was increased at f-MPA- AUC(0-12h) values > or =600 microg x h/L [corrected]. On the basis of these data and the observed variability in the pharmacokinetics of MPA, the development of monitoring strategies for this drug appears to be promising.

Child↗
PubMed2000

The monoethylglycinexylidide (MEGX) test as a marker of hepatic dysfunction in septic patients with pneumonia.

The aim of this study was to monitor hepatic function in patients with pneumonia meeting the sepsis criteria of the American College of Chest Physicians/Society of Critical Care Medicine (ACCP/SCCM) and to determine if hepatic dysfunction is related to the systemic inflammatory response. Twenty patients were recruited. The monoethylglycinexylidide (MEGX) test was carried out on days 1-10 after admittance to the intensive care unit. Blood samples for determination of serum concentrations of hyaluronic acid, C-reactive protein (CRP), interleukin (IL)-6, IL-8, IL-10 and conventional liver function tests (aspartate aminotransferase, alanine aminotransferase, bilirubin, albumin) were also drawn. Patients were classified into two groups according to illness severity estimated by the simplified acute physiology score (SAPS II) on the day of admission. Patients in group I (n=10) had a SAPS II probability of mortality >3% while those in group II (n=10) had a SAPS II < 3%. The MEGX level over the first five days was significantly lower in group I than in group II (p<0.0001). Significant inverse correlations during the first 5 days were observed between the MEGX 30 min test results and IL-6, CRP and SAPS II and more modest correlations with hyaluronic acid (p=0.0025) and IL-10 (p=0.021). The conventional liver function tests did not differ between the two groups and were mostly within the respective reference ranges. We conclude that the MEGX test is a sensitive marker of liver dysfunction early in sepsis and that low MEGX values are associated with an enhanced inflammatory response.

Adult↗
PubMed2000

Use of two reporter dyes without interference in a single-tube rapid-cycle PCR: alpha(1)-antitrypsin genotyping by multiplex real-time fluorescence PCR with the LightCycler.

BACKGROUND: alpha(1)-Antitrypsin is the major plasma serine protease inhibitor. Its deficiency is mainly associated with the alleles PI*S and PI*Z and can lead to obstructive lung disease in adults and to liver cirrhosis during childhood. METHODS: A multiplex PCR method has been established that uses two sets of primers to amplify the gene regions covering the PI*S or PI*Z mutations sites. Mutation detection was performed on the LightCycler by melting curve analysis of detection probes labeled with two different fluorescent dyes, LC-Red640 and LC-Red705. RESULTS: Unequivocal genotyping results were obtained for all investigated samples in an assay time of approximately 30 min. The color compensation procedure greatly improved the readability of the resulting diagnostic melting curves. CONCLUSIONS: To our knowledge, this is the first report of simultaneous detection of two mutations in a single tube by PCR of genomic DNA and the use of two different reporter dyes with the LightCycler color compensation feature. This approach is a rapid, convenient, and economic alternative to other methods described to date for the detection of alpha(1)-antitrypsin deficiency alleles.

DNA↗