P2RX7 genotype association in severe sepsis identified by a novel Multi-Individual Array for rapid screening and replication of risk SNPs.

BACKGROUND: Functional single nucleotide polymorphisms (SNPs) are relevant to individual therapeutic approaches and may play a role in disease susceptibility. Genome-wide scans, which are now widely applied to detect disease-associated SNPs, provide only limited evidence about SNP associations. Their usefulness as disease markers requires appropriate phenotype analysis and retesting of the gene providing SNP information. Larger data sets of thousands of samples are necessary to confirm the suggested SNPs. METHODS: We applied a newly established microarray-based technology that significantly accelerates and simplifies such studies. A tailor-made microarray surface chemistry, sample/probe immobilization and a primer extension reaction are central to the multi-individual array (MIA) platform, which simultaneously identifies the same variable nucleotide in thousands of samples. The set of SNPs to be typed for is highly flexible and can be adapted to the demands of defined clinical questions. RESULTS: A MIA-SNP analysis of functional SNPs in the P2RX7 calcium channel is presented. One risk genotype has been verified by functional analysis using patch clamping. Two clinically relevant genotypes composed of 5 functional SNPs in the P2RX7 gene have been identified in patients with severe sepsis and septic shock, whereas no significant association has been found in patient suffering from hemophagocytic syndromes. CONCLUSIONS: These results support a functional SNP genotyping of the P2RX7 gene in patients at risk of severe sepsis following surgical trauma.

Effect of Bifidobacterium lactis on the incidence of nosocomial infections in very-low-birth-weight infants: a randomized controlled trial.

BACKGROUND: Nosocomial infections endanger preterm infants. OBJECTIVE: The aim of the present controlled randomized trial was to investigate whether Bifidobacterium lactis reduces the incidence of nosocomial infections in infants with very low birth weight (VLBW; <1,500 g) <30 weeks of gestation. PATIENTS AND METHODS: In a randomized controlled trial, 183 VLBW infants <30 weeks of gestation were stratified according to gestational age (23-26 and 27-29 weeks) and early antibiotic therapy (days 1-3, yes or no) and randomly assigned to have their milk feedings supplemented with B. lactis (6 x 2.0 x 10(9) CFU/kg/day, 12 billion CFU/kg/day) or placebo for the first 6 weeks of life. Primary outcome was the 'incidence density' of nosocomial infections defined as periods of elevated C-reactive protein (>10 mg/l) from day 7 after initiation of milk feedings until the 42nd day of life (number of nosocomial infections/total number of patient days). The main secondary outcome was necrotizing enterocolitis (NEC; >or=stage 2). RESULTS: There were 93 infants in the B. lactis group and 90 in the placebo group. There was no significant difference between the two groups with regard to the incidence density of nosocomial infections (0.021 vs. 0.016; p = 0.9, chi(2) test). There were 2 cases of NEC in the B. lactis group and 4 in the placebo group. None of the blood cultures grew B. lactis. CONCLUSION: In the present setting, B. lactis at a dosage of 6 x 2.0 x 10(9) CFU/kg/day (12 billion CFU/kg/day) did not reduce the incidence density of nosocomial infections in VLBW infants. No adverse effect of B. lactis was observed.

Chromosomal speciation of humans and chimpanzees revisited: studies of DNA divergence within inverted regions.

The human and chimpanzee karyotypes are distinguishable in terms of nine pericentric inversions. According to the recombination suppression model of speciation, these inversions could have promoted the process of parapatric speciation between hominoid populations ancestral to chimpanzees and humans. Were recombination suppression to have occurred in inversion heterozygotes, gene flow would have been reduced, resulting in the accumulation of genetic incompatibilities leading to reproductive isolation and eventual speciation. In an attempt to detect the molecular signature of such events, the sequence divergence of non-coding DNA was compared between humans and chimpanzees. Precise knowledge of the locations of the inversion breakpoints permitted accurate discrimination between inverted and non-inverted regions. Contrary to the predictions of the recombination suppression model, sequence divergence was found to be lower in inverted chromosomal regions as compared to non-inverted regions, albeit with borderline statistical significance. Thus, no signature of recombination suppression resulting from inversion heterozygosity appears to be detectable by analysis of extant human and chimpanzee non-coding DNA. The precise delineation of the inversion breakpoints may nevertheless still prove helpful in identifying potential speciation-relevant genes within the inverted regions.

A comparison of the variability spectra of two genomic loci in a European group of individuals reveals fundamental differences pointing to selection or a population bottleneck.

Knowledge about the variability spectra of neutrally evolving sequences in a population is a prerequisite for the identification of genes, which may have been under positive selection during recent human evolution. Here, we report the results of a re-sequencing project of a presumably neutrally evolving chromosome 22 locus with a severely reduced recombination frequency in a group of 24 individuals of German origin. The comparison of these data with the results of a similar analysis of a chromosome 17 locus revealed striking differences, although the same group of individuals was used. For the chromosome 17 locus two well-separated groups of sequences, a positive value of Tajima's D and a TMRCA of 700,000 years were observed. In contrast, the sequences from the chromosome 22 locus were found to be relatively homogeneous, with no deep splits between subgroups; the obtained value for Tajima's D was negative and the TMRCA was only 260,000 years. These discrepancies may be explained by selection or demographic processes. Regarding demography, the most plausible explanation is the assumption of a severe bottleneck in the history of the European population: in the case of the chromosome 17 locus two ancient lineages passed this bottleneck; for the chromosome 22 locus it was only one ancient lineage.

Mutation screening and association study of RNASEL as a prostate cancer susceptibility gene.

To date, germline mutations have been found in three candidate genes for hereditary prostate cancer: ELAC2 at 17p11, RNASEL at 1q25 and MSR1 at 8p22. RNASEL, encoding the 2',5'-oligoadenylate-dependant RNase L, seems to have rare mutations in different ethnicities, such as M1I in Afro-Americans, E265X in men of European descent and 471delAAAG in Ashkenazi Jews. In order to evaluate the relevance of RNASEL in the German population, we sequenced its open reading frame to determine the spectrum and frequency of germline mutations. The screen included 303 affected men from 136 Caucasian families, of which 45 met the criteria for hereditary prostate cancer. Variants were analysed using a family-based association test, and genotyped in an additional 227 sporadic prostate cancer patients and 207 controls. We identified only two sib pairs (1.4% of our families) cosegregating conspicuous RNASEL variants with prostate cancer: the nonsense mutation E265X, and a new amino-acid substitution (R400P) of unknown functional relevance. Both alleles were also found at low frequencies (1.4 and 0.5%, respectively) in controls. No significant association of polymorphisms (I97L, R462Q and D541E) was observed, neither in case-control analyses nor by family-based association tests. In contrast to previous reports, our study does not suggest that common variants (i.e. R462Q) modify disease risk. Our results are not consistent with a high penetrance of deleterious RNASEL mutations. Due to the low frequency of germline mutations present in our sample, RNASEL does not have a significant impact on prostate cancer susceptibility in the German population.

Haemodialysis-membrane biocompatibility and mortality of patients with dialysis-dependent acute renal failure: a prospective randomised multicentre trial. International Multicentre Study Group.

BACKGROUND: There is controversy as to whether haemodialysis-membrane biocompatibility (ie, the potential to activate complement and neutrophils) influences mortality of patients with acute renal failure. We did a prospective randomised multicentre trial in patients with dialysis-dependent acute renal failure treated with two different types of low-flux membrane. METHODS: 180 patients with acute renal failure were randomly assigned bioincompatible Cuprophan (n=90) or polymethyl-methacrylate (n=90) membranes. The main outcome was survival 14 days after the end of therapy (treatment success). Odds ratios for survival were calculated and the two groups were compared by Fisher's exact test. Analyses were based on patients treated according to protocol (76 Cuprophan, 84 polymethyl methacrylate). FINDINGS: At the start of dialysis, the groups did not differ significantly in age, sex, severity of illness (as calculated by APACHE II scores), prevalence of oliguria, or biochemical measures of acute renal failure. 44 patients (58% [95% CI 46-69]) assigned Cuprophan membranes and 50 patients (60% [48-70]) assigned polymethyl-methacrylate membranes survived. The odds ratio for treatment failure on Cuprophan compared with polymethyl-methacrylate membranes was 1.07 (0.54-2.11; p=0.87). No difference between Cuprophan and polymethyl-methacrylate membranes was detected when the analysis was adjusted for age and APACHE II score. 18 patients in the Cuprophan group and 20 in the polymethyl-methacrylate group had clinical complications of therapy (mainly hypotension). INTERPRETATION: There were no differences in outcome for patients with dialysis-dependent acute renal failure between those treated with Cuprophan membranes and those treated with polymethyl-methacrylate membranes.