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Biomedical subjects

Christine Mannhalter

Publications and source records attributed to Christine Mannhalter.

At least 37 records · Page 2Linked to original sources
PubMed2005

Impact of alphaENaC polymorphisms on the risk of ischemic cerebrovascular events: a multicenter case-control study.

BACKGROUND: Amiloride-sensitive epithelial sodium channels (ENaCs) are important candidates in the development of hypertension, which is a major risk factor for stroke. Two single-nucleotide polymorphisms (SNPs) in the gene that encodes the ENac alpha-subunit (alphaENaC) have been identified. We evaluated those SNPs for a possible association with ischemic cerebrovascular events (ICEs). METHODS AND RESULTS: We genotyped 1399 patients with ICEs [median age, 70 years; interquartile range, 58-78 years; 745 (53%) men] and 1076 control individuals without vascular disease [47 (39-58) years; 557 (52%) men] for the SNPs Trp493Arg and Ala663Thr. The SNP frequencies at nucleotide 3977 (Trp493Arg) in the alphaENaC gene were significantly different in patients and controls. Carriers of 493Arg had a 1.78-fold increased risk (95% confidence interval, 1.02-3.12) for ICEs compared with Trp/Trp carriers. Interaction analysis revealed that the relative risk was even higher in women in the lowest age tertile [adjusted odds ratio, 3.26 (1.10-9.72)]. CONCLUSIONS: Carriers of the 493Arg allele are at increased risk for ICEs compared with Trp/Trp carriers. The effect is independent of traditional vascular risk factors and is particularly evident in younger women. The Trp493Arg variant in alphaENaC may represent an important candidate genetic susceptibility factor in the development of ICEs.

Adult↗
PubMed2005

Spectrum of germ-line MLH1 and MSH2 mutations in Austrian patients with hereditary nonpolyposis colorectal cancer.

BACKGROUND: Germ-line mutations in mismatch repair genes are associated with the hereditary nonpolyposis colorectal cancer (HNPCC) syndrome, which is characterized by susceptibility to cancer of the colon, endometrium, small bowel or urothelium at an unusually young age and with a high degree of penetration in all generations. MATERIAL AND METHODS: One hundred and nine individuals from 46 Austrian families who fulfilled the Amsterdam criteria (n = 29) or at least one of the Bethesda guidelines (n = 17) were analyzed for mutations in MLH1 and MSH2. Microsatellite instability was determined in the tumors of index persons and affected relatives. RESULTS AND CONCLUSION: High-grade instability was present in 60.6% of the tumor samples from index patients. Twenty-three germ-line DNA sequence variants in 24/46 families and four somatic mutations in three tumors were detected in MLH1 and MSH2. Fifteen mutations are novel. None of the newly identified germ-line variants was found in 100 alleles of healthy control individuals. We were able to characterize two intronic variants (MLH1 c.589-10T>A; MSH2 c.367-1G>A) with regard to their effect on mRNA. Both created new splice sites that replaced the regular ones. Germ-line mutations occurred in 44.8% of the families fulfilling the Amsterdam criteria and in 35.3% of the Bethesda patients. The detection of a pathogenic mutation was strongly correlated with microsatellite instability in the tumor DNA (p=0.007). This study is the first comprehensive report of mutations in mismatch repair genes in Austrian patients with HNPCC.

Adaptor Proteins, Signal Transducing↗
PubMed2005

PAI-1 4G/5G insertion/deletion promoter polymorphism and microvascular complications in type 2 diabetes mellitus.

BACKGROUND: Plasminogen activator inhibitor-1 (PAI-1) plays an important role in the regulation of fibrinolysis and extracellular matrix turnover. PAI-1 4G/5G insertion/deletion polymorphism in the PAI-1 promoter region has been shown to modulate PAI-1 plasma levels. We investigated the relationship between this polymorphism and the prevalence of diabetic nephropathy and retinopathy in patients with type 2 diabetes in the Austrian population. PATIENTS AND METHODS: 147 consecutive patients with type 2 diabetes mellitus (96 men, 51 women; median age, 65 years; IQR, 59-71) were analyzed for the PAI-1 4G/5G genotype. RESULTS: The genotype distribution in the individuals tested was as follows: 17% (n = 25) 5G/5G, 54% (n = 80) 4G/5G, and 29% (n = 42) 4G/4G. Patients homozygous for allele 4G had a significantly higher risk of diabetic proliferative retinopathy than patients without signs of diabetic retinopathy or nonproliferative retinopathy (OR, 7.3; 95% CI, 1.4-38.8; P = 0.02). No significant associations were observed between the PAI-1 genotype and the presence of albuminuria. CONCLUSION: According to our results, diabetic proliferative retinopathy might be associated with the prevalence of PAI-1 genotype 4G/4G.

Aged↗
PubMed2005

Influence of functional haplotypes in the drug transporter gene ABCB1 on central nervous system drug distribution in humans.

BACKGROUND AND OBJECTIVE: Single nucleotide polymorphisms in the human multidrug-resistance gene ABCB1 have been reported to be associated with altered expression and function of P-glycoprotein, an efflux transporter, expressed at the blood-brain barrier. To test whether certain ABCB1 haplotypes contribute to interindividual differences in central nervous system drug distribution, brain distribution of a model P-glycoprotein substrate, the calcium channel inhibitor verapamil, was measured by positron emission tomography (PET) in 2 groups of healthy volunteers. METHODS: Ten homozygous carriers (cases) of the TTT haplotype (3435T, 1236T, and 2677T) and 10 controls homozygous for the wild-type CGC haplotype (3435C, 2677G, and 1236C) were administered a mean intravenous bolus of 412 +/- 114 MBq carbon 11-labeled verapamil containing less than 15 nmol of unlabeled verapamil. PET imaging of brain tissue and venous blood sampling were performed for 1 hour after dosing. RESULTS: As a measure of brain penetration, the ratio of PET area under the time-radioactivity curve (AUC) to plasma AUC was calculated from time-radioactivity curves, with a mean ratio of 1.1 +/- 0.3 (SD) (95% confidence interval, 0.9-1.3) for cases and 1.1 +/- 0.2 (95% confidence interval, 0.9-1.2) for controls, respectively (P = .96). Mean brain AUC values were 31.2 +/- 3.9 and 35.7 +/- 5.7 for the TTT and CGC haplotype, respectively (P = .11). Plasma AUCs were not significantly different. CONCLUSION: No difference in the brain distribution of [(11)C]verapamil could be detected in healthy volunteers differing in ABCB1 haplotypes.

Adult↗
PubMed2005

An unusual case of myelodysplastic syndrome with prolonged clonal stability, indolent clinical course over a decade, and spontaneous regression of AML in the terminal phase.

An unusual case of secondary acute myeloid leukemia (AML) with indolent clinical course is described. The patient, a 67-yr-old female, had first been diagnosed to suffer from low-risk myelodysplastic syndrome, subtype refractory anemia with ringed sideroblasts, in 1992. In 2001, transformation to secondary AML with an increase in bone marrow blasts (>20%) and thrombocytopenia, was found. The patient did not require cytoreductive drugs. Rather, during the following months, spontaneous improvement of peripheral blood cells with normalization of platelets and decrease in the red cell transfusion frequency, were noted. In October 2002, she even became transfusion independent. However, the bone marrow still showed AML with >20% blasts. These blast cells exhibited a monoclonal pattern in the human androgen receptor (HUMARA) assay. However, no chromosomal defects occurred during a total observation period of 14 yr. We hypothesize that clonal stability may have contributed to the indolent course of the disease in this patient. The exact mechanisms underlying clinical and genetic stability remain unknown, however.

Bone Marrow↗
PubMed2005

Opposite effects of CX3CR1 receptor polymorphisms V249I and T280M on the development of acute coronary syndrome. A possible implication of fractalkine in inflammatory activation.

Several lines of evidence suggest that the chemokine fractalkine (FKN) and its receptor CX3CR1 contribute to the accumulation of leukocytes in the atherosclerotic plaque. The M280 allele of the CX3CR1T280M polymorphism modulates leukocyte recruitment and is associated with lower prevalence of cardiovascular disease. The influence of V249I, another CX3CR1 polymorphism, is discussed controversially. We investigated the association of the alleles M280 and I249 of CX3CR1 with coronary artery disease (CAD) and with acute coronary syndrome (ACS). Additionally, we assessed their association with the soluble ligand FKN and inflammatory activation measured by high sensitivity C-reactive protein (hsCRP). The genotypes of the V249I and T280M polymorphisms were determined in 1152 patients with suspected CAD.720 (62.5%) individuals showed significant CAD with an ACS prevalence of 59.3%. Using multivariate regression, we found a harmful influence of I249 (adjusted OR=1.8, P<0.03) and a protective effect of M280 (adjusted OR=0.6, P<0.04) on the occurrence of ACS in patients with CAD. Correspondingly, patients with I249 but without M280 (17%) were at elevated risk of ACS (OR=1.6, P<0.04). During ACS these patients (carrying only I249) had significantly higher circulating concentrations of FKN and high sensitivity C-reactive protein (1.9- and 1.6-fold). We found no association of the I249 or the M280 allele with the occurrence of CAD. In conclusion, I249 and M280 have opposite effects on the occurrence of ACS. The presence of I249 not "balanced" by M280 confers an elevated risk of ACS. A FKN-mediated enhanced inflammatory activation might explain this increased risk.

Acute Disease↗
PubMed2005

Simultaneous analysis of MDR1 C3435T, G2677T/A, and C1236T genotypes by multiplexed mutagenically separated PCR.

P-glycoprotein (PGP) encoded by the multi-drug-resistance 1 (MDR1) gene is a member of the ATP-binding cassette (ABC) transporter family, drug-transporting proteins involved in the bioavailability and pharmacokinetics of various drugs. Several single nucleotide polymorphisms (SNPs) in the MDR1 gene have been identified so far that may influence PGP expression levels and function. Thus, genotyping for MDR1 polymorphisms and determining specific haplotypes may become an important tool in predicting individual susceptibility to developing drug resistance. We developed a new multiplexed allele-specific PCR method based on the principle of mutagenically separated PCR (MS-PCR) for rapid and reliable simultaneous genotyping of the C3435T polymorphism in exon 26 of the MDR1 gene and two additional SNPs (G2677T/A in exon 21 and C1236T in exon 12), which are in linkage disequilibrium with MDR1 C3435T. The accuracy and reliability of this method was confirmed by sequencing the respective regions in the MDR1 gene. This newly developed MDR1 MS-PCR will facilitate fast, accurate and economic analysis of MDR1 genotypes and will provide important information in optimizing individual therapeutic approaches.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Reference materials (RMs) for analysis of the human factor II (prothrombin) gene G20210A mutation.

The Scientific Committee of Molecular Biology Techniques (C-MBT) in Clinical Chemistry of the IFCC has initiated a joint project in co-operation with the European Commission, Joint Research Centre, Institute of Reference Materials and Measurements to develop and produce plasmid-type reference materials (RMs) for the analysis of the human prothrombin gene G20210A mutation. Although DNA tests have a high impact on clinical decision-making and the number of tests performed in diagnostic laboratories is high, issues of quality and quality assurance exist, and currently only a few RMs for clinical genetic testing are available. A gene fragment chosen was produced that spans all primer annealing sites published to date. Both the wild-type and mutant alleles of this gene fragment were cloned into a pUC18 plasmid and two plasmid RMs were produced. In addition, a mixture of both plasmids was produced to mimic the heterozygous genotype. The present study describes the performance of these reference materials in a commutability study, in which they were tested by nine different methods in 13 expert laboratories. This series of plasmid RMs are, to the best of our knowledge, the first plasmid-type clinical genetic RMs introduced worldwide.

Base Sequence↗
PubMed2005

Haptoglobin phenotype 2-2 as a potentially new risk factor for spontaneous venous thromboembolism.

BACKGROUND AND OBJECTIVES: Haptoglobin (Hp) is a plasma protein that binds free hemoglobin and thus prevents catalysis of reactive oxygen species by the Fenton reaction. A genetic polymorphism has been described that leads to the generation of two distinct alleles, Hp1 and Hp2, which define three major haptoglobin phenotypes, denoted Hp1-1, Hp2-1 and Hp2-2. Hp2-2 has been reported to be associated with the risk of atherosclerosis and coronary heart disease. In our study we investigated the association of haptoglobin genotype and phenotype with the risk of spontaneous venous thromboembolism (VTE). DESIGN AND METHODS: One hundred and twenty-eight patients with a history of spontaneous deep vein thrombosis (70 women, 58 men), 105 with spontaneous symptomatic pulmonary embolism (58 women, 47 men) and 122 healthy controls (60 women, 62 men) were enrolled. Haptoglobin levels were measured immunonephelometrically and phenotypes were detected by polyacrylamide gel electrophoresis and subsequent immunoblotting. RESULTS: The Hp2-2 phenotype was significantly more prevalent in patients (42%) than in controls (30%) and significantly increased the risk for VTE in univariable (odds ratio=1.6, 95% confidence interval [1.0-2.6], p=0.04) and multivariable analyses (odds ratio=1.9 [1.0-3.4], p=0.04). Hp2-2 (n=134) was associated with significantly lower haptoglobin levels (median=89.7 mg/dL) than Hp2-1 (n=170, median = 123.5 mg/dL, p<0.001) or Hp1-1 (n=51, median=142.8 mg/dL, p<0.001). INTERPRETATION AND CONCLUSIONS: Our study gives the first evidence that Hp2-2 represents a risk factor for spontaneous VTE, presumably through a pathophysiological mechanism similar to that in arterial disease.

Adult↗
PubMed2005

Interleukin-1 gene cluster variants and abdominal aortic aneurysms.

Inflammation is a key factor in the pathogenesis of abdominal aortic aneurysms (AAA). Interleukin 1 (IL-1), a fundamental regulator of the inflammatory cascade, has been shown to be involved in this process. Several functional polymorphisms in the IL-1 gene cluster are known. In this matched case-control study, we investigated a potential association between six genetic variants in IL-1 and IL-1 receptor antagonist (IL-1 RN) with AAA. We enrolled 405 individuals, 135 consecutive patients with AAA were individually age- and sex-matched to 270 patients with coronary artery disease (CAD). Traditional cardiovascular risk factors and IL-1 genotypes were determined, and the distribution of six single nucleotide polymorphisms were compared between patients and controls by multivariable conditional logistic regression analysis: IL-1A (-889) C>T, IL-1A (+4845) G>T, IL-1B (-511) C>T, IL-1B (-31) C>T, IL-1B (+3954) C>T and IL-1RN (+2018) C>T. IL-1A (-889) C>T and IL-1A (+4845) G>T (kappa 0.98,95% CI 0.96 to 1.00), and IL-1B (-511) C>T and IL-1B (-31) C>T (kappa 0.98, 95% CI 0.96 to 1.00) were closely linked, therefore IL-1A (-889) C>T and IL-1B (-31) C>T were not considered for further analyses. None of the 4 remaining polymorphisms showed a significant association with AAA: IL-1RN (+2018) C>T (p = 0.061), IL-1B (+3954) C>T (p = 0.51), IL-1B (-511) C>T (p = 0.61) and IL-1A (+4845) G>T (p = 0.81). No significant first-degree interactions between the genetic variants and AAA were detected. In conclusion,these six genetic variants in the interleukin- I gene cluster do not seem to play a clinically relevant role in the pathogenesis of AAA, although we cannot rule out the existence of higher degree gene-gene or gene-environment interactions.

Aged↗
PubMed2005

Fractalkine receptor polymorphisms V2491 and T280M as genetic risk factors for restenosis.

The chemokine fractalkine (FKN) recruits leukocytes into lesions of the arterial wall, which may lead to restenosis after stenting. FKN also regulates proliferation of smooth muscle cells, another mechanism pivotal to neointimal thickening. We assessed the hypothesis that functionally important polymorphisms of the FKN receptor CX3CR1 influence restenosis after coronary stenting. Three hundred and sixty-five patients undergoing coronary stenting were genotyped for the CX3CR1 polymorphisms V2491 and T280M. Restenosis occurred in 25% of patients, and recurrent (> 1) restenosis at the target lesion in 8%. The allele 1249 was associated with an increased risk of restenosis (adjusted odds ratio 2.4, 95% confidence interval: 1.3-4.2, P = 0.003) and recurrent restenosis (odds ratio 2.7, 95% confidence interval: 1.3-5.9, P = 0.011). Particularly, patients with 1249 lacking the allele M280 were at an elevated risk of restenosis (P = 0.006) and, accordingly, the haplotype containing 1249 but not M280 was more frequent in patients with restenosis (P = 0.001). In conclusion, the CX3CR1 1249 allele is associated with an increased risk of restenosis while the CX3CR1 M280 allele might counteract the harmful influence of 1249. These findings show the importance of the chemokine FKN and genetic variations of its receptor for restenosis after coronary stenting. Recognition of these inherited risk modifiers may help to individualize treatment of coronary stenosis.

Alleles↗
PubMed2004

Thrombophilic polymorphisms--factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T mutations--and preterm birth.

AIM OF THE STUDY: To evaluate the influence of three common thrombophilic polymorphisms, factor V Leiden (FV), prothrombin G20210A (PT), and methylenetetrahydrofolate reductase (MTHFR) C677T mutations, on preterm birth of unknown cause. PATIENTS AND METHODS: A single-centre case-control study of women with preterm infants < or =35 weeks of gestation, in whom obvious maternal, uterine, and fetal causes responsible for preterm birth were excluded (n = 35). The controls were 54 women with term infants hospitalised in the same ward. RESULTS: There were no significant differences between the groups of mothers in history of fetal loss, venous or familial thrombosis, or previous preterm birth. FV was found in 8.6% of the cases, PT in 5.7%, and MTHFR mutation (homozygous) in 4.8% compared with 5.4% (p=0.292, OR 1.594, CI95% 0.303-8.384), 7.4% (p=0.379, OR 0.758, CI95% 0.131-4.374), and 4.5% (p = 0.485, OR 1.050, CI95% 0.090-12.276), respectively, in the controls. Differences in the three thrombophilic polymorphisms in the two groups of infants were also not significant. CONCLUSION: We could not demonstrate a distinct association between these thrombophilic polymorphisms and preterm birth.

Adolescent↗
PubMed2004

Interleukin-6 promoter genotype and restenosis after femoropopliteal balloon angioplasty: initial observations.

PURPOSE: To investigate whether there is an association between a functional polymorphism in the interleukin (IL)-6 gene promoter (-174)G/C and restenosis after percutaneous transluminal angioplasty (PTA) of the femoropopliteal artery. MATERIALS AND METHODS: A total of 281 patients underwent PTA of the femoropopliteal artery during the study period; 23 (8%) patients had to be excluded due to missing genetic data. We studied 258 patients with intermittent claudication (n = 174) or critical limb ischemia (n = 84). The IL-6 promoter genotype was determined from venous blood samples before intervention by using a mutagenically separated polymerase chain reaction, and patients were followed up for 6 months with duplex ultrasonography for the occurrence of restenosis (> or =50%) after angioplasty. Multivariate Cox proportional hazards analysis was performed to assess the association between the IL-6 promoter genotype and restenosis, with adjustment for possible confounders such as atherosclerotic risk factors and angiographic covariates. RESULTS: The 6-month restenosis rate was 26% (23 of 90) in patients with the (-174)GG genotype, 28% (33 of 117) with the (-174)GC genotype, and 43% (22 of 51) with the (-174)CC genotype (P =.044). Homozygous carriers of the (-174)C allele ([-174]CC) exhibited a 2.42-fold increased adjusted risk for restenosis (95% CI: 1.28, 4.58; P =.007) compared with homozygous (-174)G allele carriers ([-174]GG). Heterozygous carriers ([-174]GC) had no significantly increased restenosis risk (hazard ratio, 1.37; 95% CI: 0.84, 2.22; P =.21). CONCLUSION: The IL-6 promoter polymorphism (-174)G/C seems to influence the occurrence of restenosis after PTA. Homozygous carriers of the (-174)C allele have an increased rate of intermediate-term restenosis.

Aged↗
PubMed2004

Heme oxygenase-1 genotype and restenosis after balloon angioplasty: a novel vascular protective factor.

OBJECTIVES: We investigated the association of the heme oxygenase-1 (HO-1) promoter genotype with the inflammatory response and restenosis after balloon angioplasty. BACKGROUND: Heme oxygenase-1, which is induced by balloon angioplasty, can inhibit neointima formation and vascular remodeling. A dinucleotide repeat in the HO-1 gene promoter shows a length polymorphism that modulates HO-1 gene transcription. Short (<25 guanosine thymidine [GT]) repeats are associated with a 10-fold greater up-regulation of HO-1 than are longer repeats. METHODS: We studied 381 consecutive patients who underwent femoropopliteal balloon angioplasty (n = 210) and comparison groups with femoropopliteal stenting (n = 68) and lower limb angiography (n = 103). C-reactive protein (CRP) was measured at baseline, 24, and 48 h. We evaluated patency at six months by duplex sonography and assessed the association of the length of GT repeats in the HO-1 gene promoter with postintervention CRP and restenosis. RESULTS: Restenosis within six months was found in 74 patients (35%) after balloon angioplasty and in 21 patients (31%) after stenting. After balloon angioplasty, carriers of the short length (<25 GT) dinucleotide repeats had a lower postintervention CRP at 24 h (p = 0.009) and 48 h (p < 0.001) and a reduced risk for restenosis (adjusted relative risk 0.43, 95% confidence interval: 0.24 to 0.71, p < 0.001) compared with patients with longer alleles. After stenting or angiography, we found no association between the HO-1 genotype with CRP or restenosis. CONCLUSIONS: The HO-1 promoter genotype that controls the degree of HO-1 up-regulation in response to stress stimuli is associated with the postintervention inflammatory response and the restenosis risk after balloon angioplasty.

Aged↗