Backbone resonance assignments for a homolog of the essential ribosome biogenesis factor Fap7 from P. horikoshii in its nucleotide-free and -bound forms

The protein “factor activating Pos9 (Skn7)”, Fap7, is an essential protein in yeast and plays an important role in the biogenesis of the small ribosomal subunit. In eukaryotes, the final processing step of the small ribosomal subunit RNA is the endonucleolytic cleavage of 20S pre-rRNA at cleavage site D yielding mature 18S rRNA. Depletion of Fap7 in yeast leads to a dramatic accumulation of 20S pre-rRNA and a concomitant decrease in 18S rRNA in the cytoplasm. In addition, these cells contain higher levels of 60S, but decreased numbers of 40S ribosomal subunits. Fap7 contains a P-loop like motif placing it in a class with NTPases and kinases and a role for it as an adenylate kinase has been suggested. Up to now both the structure of Fap7 and its detailed function during ribosome biogenesis remain elusive. Here, we present the backbone NMR assignments of a Fap7 homolog from the thermophilic archaeon Pyrococcus horikoshii in its nucleotide free form and bound to the adenylate kinase inhibitor AP₅A.     

Frequency of hybridization between Ostrinia nubilalis E‐and Z‐pheromone races in regions of sympatry within the United States

Female European corn borer, Ostrinia nubilalis, produce and males respond to sex pheromone blends with either E‐ or Z‐Δ11‐tetradecenyl acetate as the major component. E‐ and Z‐race populations are sympatric in the Eastern United States, Southeastern Canada, and the Mediterranean region of Europe. The E‐ and Z‐pheromone races of O. nubilalis are models for incipient species formation, but hybridization frequencies within natural populations remain obscure due to lack of a high‐throughput phenotyping method. Lassance et al. previously identified a pheromone gland‐expressed fatty‐acyl reductase gene (pgfar) that controls the ratio of Δ11‐tetradecenyl acetate stereoisomers. We identified three single nucleotide polymorphism (SNP) markers within pgfar that are differentially fixed between E‐ and Z‐race females, and that are ≥98.2% correlated with female pheromone ratios measured by gas chromatography. Genotypic data from locations in the United States demonstrated that pgfar‐z alleles were fixed within historically allopatric Z‐pheromone race populations in the Midwest, and that hybrid frequency ranged from 0.00 to 0.42 within 11 sympatric sites where the two races co‐occur in the Eastern United States (mean hybridization frequency or heterozygosity (H_O) = 0.226 ± 0.279). Estimates of hybridization between the E‐ and Z‐races are important for understanding the dynamics involved in maintaining race integrity, and are consistent with previous estimates of low levels of genetic divergence between E‐ and Z‐races and the presence of weak prezygotic mating barriers.     

Poromicromechanics reveals that physiological bone strains induce osteocyte-stimulating lacunar pressure

Mechanical loads which are macroscopically acting onto bony organs, are known to influence the activities of biological cells located in the pore spaces of bone, in particular so the signaling and production processes mediated by osteocytes. The exact mechanisms by which osteocytes are actually able to “feel” the mechanical loading and changes thereof, has been the subject of numerous studies, and, while several hypotheses have been brought forth over time, this topic has remained a matter of debate. Relaxation times reported in a recent experimental study of Gardinier et al. (Bone 46(4):1075–1081, 2010) strongly suggest that the lacunar pores are likely to experience, during typical physiological load cycles, not only fluid transport, but also undrained conditions. The latter entail the buildup of lacunar pore pressures, which we here quantify by means of a thorough multiscale modeling approach. In particular, the proposed model is based on classical poroelasticity theory, and able to account for multiple pore spaces. First, the model reveals distinct nonlinear dependencies of the resulting lacunar (and vascular) pore pressures on the underlying bone composition, highlighting the importance of a rigorous multiscale approach for appropriate computation of the aforementioned pore pressures. Then, the derived equations are evaluated for macroscopic (uniaxial as well as hydrostatic) mechanical loading of physiological magnitude. The resulting model-predicted pore pressures agree very well with the pressures that have been revealed, by means of in vitro studies, to be of adequate magnitude for modulating the responses of biological cells, including osteocytes. This underlines that osteocytes may respond to many types of loading stimuli at the same time, in particular so to fluid flow and hydrostatic pressure.     

Identification and characterization of 10 polymorphic microsatellite loci in the German cockroach,Blattella germanica

Primer sequences and initial characterization are presented for 10 microsatellite loci isolated from the German cockroach, Blattella germanica. In a sample of 30 individuals from a single population sample, all loci were polymorphic with two to 12 alleles segregating per locus and levels of observed heterozygosity ranging from 0.27 to 0.92. One locus showed a deficit of heterozygotes. Experimental conditions are described for polymerase chain reaction multiplexing, which enables the genotyping of eight loci in three electrophoretic runs consisting of one set of three and two sets of two markers. Seven primer sets cross‐amplify in the related Blattella asahinai.     

Monitoring clinical trials with multiple arms

In order to benefit from the substantial overhead expenses of a large group sequential clinical trial, the simultaneous investigation of several competing treatments becomes more popular. If at some interim analysis any treatment arm reveals itself to be inferior to any other treatment under investigation, this inferior arm may be or may even need to be dropped for ethical and/or economic reasons. Recently proposed methods for monitoring and analysis of group sequential clinical trials with multiple treatment arms are compared and discussed. The main focus of the article is on the application and extension of (adaptive) closed testing procedures in the group sequential setting that strongly control the familywise error rate. A numerical example is given for illustration.     

Hypoxia induces mitochondrial DNA damage and stimulates expression of a DNA repair enzyme, the Escherichia coli MutY DNA glycosylase homolog (MYH), in vivo, in the rat brain

Hypoxia-associated, acutely reduced blood oxygenation can compromise energy metabolism, alter oxidant/antioxidant balance and damage cellular components, including DNA. We show in vivo, in the rat brain that respiratory hypoxia leads to formation of the oxidative DNA lesion, 8-hydroxy-2'-deoxyguanosine (oh8dG), a biomarker for oxidative DNA damage and to increased expression of a DNA repair enzyme involved in protection of the genome from the mutagenic consequences of oh8dG. The enzyme is a homolog of the Escherichia coli MutY DNA glycosylase (MYH), which excises adenine residues misincorporated opposite the oxidized base, oh8dG. We have cloned a full-length rat MYH (rMYH) cDNA, which encodes 516 amino acids, and by in situ hybridization analysis obtained expression patterns of rMYH mRNA in hippocampal, cortical and cerebellar regions. Ensuing hypoxia, mitochondrial DNA damage was induced and rMYH expression strongly elevated. This is the first evidence for a regulated expression of a DNA repair enzyme in the context of respiratory hypoxia. Our findings support the premise that oxidative DNA damage is repaired in neurons and the possibility that the hypoxia-induced expression of a DNA repair enzyme in the brain represents an adaptive mechanism for protection of neuronal DNA from injurious consequences of disrupted energy metabolism and oxidant/antioxidant homeostasis.     

Resampling in Multiple‐Dose Factorial Designs

Multiple‐dose factorial designs may provide confirmatory evidence that (fixed) combination drugs are superior to either component drug alone. Moreover, a useful and safe range of dose combinations may be identified. In our study, we focus on (A) adjustments of the overall significance level made necessary by multiple testing, (B) improvement of conventional statistical methods with respect to power, distributional assumptions and dimensionality, and (C) construction of corresponding simultaneous confidence intervals. We propose novel resampling algorithms, which in a simple way take the correlation of multiple test statistics into account, thus improving power. Moreover, these algorithms can easily be extended to combinations of more than two component drugs and binary outcome data. Published data summaries from a blood pressure reduction trial are analysed and presented as a worked example. An implementation of the proposed methods is available online as an R package.     

Comparison of Conventional versus Steerable-Catheter Guided Coronary Sinus Lead Positioning in Patients Undergoing Cardiac Resynchronization Device Implantation

Objectives

The aim of this study was to compare conventional versus steerable catheter guided coronary sinus (CS) cannulation in patients with advanced heart failure undergoing cardiac resynchronization therapy (CRT).

Background

Steerable catheter guided coronary sinus cannulation could reduce fluoroscopy time and contrast medium use during CRT implantation.

Methods

176 consecutive patients with ischemic and non-ischemic heart failure undergoing CRT implantation from January 2008 to December 2012 at the University Hospital of Cologne were identified. During the study period two concurrent CS cannulation techniques were used: standard CS cannulation technique (standard-group, n = 113) and CS cannulation using a steerable electrophysiology (EP) catheter (EPCath-group, n = 63). Propensity-score matched pairs of conventional and EP-catheter guided CS cannulation made up the study population (n = 59 pairs). Primary endpoints were total fluoroscopy time and contrast medium amount used during procedure.

Results

The total fluoroscopy time was 30.9 min (interquartile range (IQR), 19.9–44.0 min) in the standard-group and 23.4 min (IQR, 14.2-34-2 min) in the EPCath-group (p = 0.011). More contrast medium was used in the standard-group (60.0 ml, IQR, 30.0–100 ml) compared to 25.0 ml (IQR, 20.0–50.0 ml) in the EPCath-group (P<0.001).

Conclusions

Use of steerable EP catheter was associated with significant reduction of fluoroscopy time and contrast medium use in patients undergoing CRT implantation.