Regulation of translation factors during hindlimb unloading and denervation of skeletal muscle in rats

In the rat, denervation and hindlimb unloading are two commonly employed models used to study skeletal muscle atrophy. In these models, muscle atrophy is generally produced by a decrease in protein synthesis and an increase in protein degradation. The decrease in protein synthesis has been suggested to occur by an inhibition at the level of protein translation. To better characterize the regulation of protein translation, we investigated the changes that occur in various translation initiation and elongation factors. We demonstrated that both hindlimb unloading and denervation produce alterations in the phosphorylation and/or total amount of the 70-kDa ribosomal S6 kinase, eukaryotic initiation factor 2 alpha-subunit, and eukaryotic elongation factor 2. Our findings indicate that the regulation of these protein translation factors differs between the models of atrophy studied and between the muscles evaluated (e.g., soleus vs. extensor digitorum longus).     

Parameters Influencing Baseline HIV-1 Genotypic Tropism Testing Related to Clinical Outcome in Patients on Maraviroc

ObjectivesWe analysed the impact of different parameters on genotypic tropism testing related to clinical outcome prediction in 108 patients on maraviroc (MVC) treatment.Methods87 RNA and 60 DNA samples were used. The viral tropism was predicted using the geno2pheno_[coreceptor] and T-CUP tools with FPR cut-offs ranging from 1%-20%. Additionally, 27 RNA and 28 DNA samples were analysed in triplicate, 43 samples with the ESTA assay and 45 with next-generation sequencing. The influence of the genotypic susceptibility score (GSS) and 16 MVC-resistance mutations on clinical outcome was also studied.ResultsConcordance between single-amplification testing compared to ESTA and to NGS was in the order of 80%. Concordance with NGS was higher at lower FPR cut-offs. Detection of baseline R5 viruses in RNA and DNA samples by all methods significantly correlated with treatment success, even with FPR cut-offs of 3.75%-7.5%. Triple amplification did not improve the prediction value but reduced the number of patients eligible for MVC. No influence of the GSS or MVC-resistance mutations but adherence to treatment, on the clinical outcome was detected.ConclusionsProviral DNA is valid to select candidates for MVC treatment. FPR cut-offs of 5%-7.5% and single amplification from RNA or DNA would assure a safe administration of MVC without excluding many patients who could benefit from this drug. In addition, the new prediction system T-CUP produced reliable results.     

Distance measures and optimization spaces in quantitative fatty acid signature analysis

Quantitative fatty acid signature analysis has become an important method of diet estimation in ecology, especially marine ecology. Controlled feeding trials to validate the method and estimate the calibration coefficients necessary to account for differential metabolism of individual fatty acids have been conducted with several species from diverse taxa. However, research into potential refinements of the estimation method has been limited. We compared the performance of the original method of estimating diet composition with that of five variants based on different combinations of distance measures and calibration‐coefficient transformations between prey and predator fatty acid signature spaces. Fatty acid signatures of pseudopredators were constructed using known diet mixtures of two prey data sets previously used to estimate the diets of polar bears Ursus maritimus and gray seals Halichoerus grypus, and their diets were then estimated using all six variants. In addition, previously published diets of Chukchi Sea polar bears were re‐estimated using all six methods. Our findings reveal that the selection of an estimation method can meaningfully influence estimates of diet composition. Among the pseudopredator results, which allowed evaluation of bias and precision, differences in estimator performance were rarely large, and no one estimator was universally preferred, although estimators based on the Aitchison distance measure tended to have modestly superior properties compared to estimators based on the Kullback–Leibler distance measure. However, greater differences were observed among estimated polar bear diets, most likely due to differential estimator sensitivity to assumption violations. Our results, particularly the polar bear example, suggest that additional research into estimator performance and model diagnostics is warranted.     

Impulsivity and Concussion in Juvenile Rats: Examining Molecular and Structural Aspects of the Frontostriatal Pathway

Impulsivity and poor executive control have been implicated in the pathogenesis of many developmental and neuropsychiatric disorders. Similarly, concussions/mild traumatic brain injuries (mTBI) have been associated with increased risk for neuropsychiatric disorders and the development of impulsivity and inattention. Researchers and epidemiologists have therefore considered whether or not concussions induce symptoms of attention-deficit/hyperactivity disorder (ADHD), or merely unmask impulsive tendencies that were already present. The purpose of this study was to determine if a single concussion in adolescence could induce ADHD-like impulsivity and impaired response inhibition, and subsequently determine if inherent impulsivity prior to a pediatric mTBI would exacerbate post-concussion symptomology with a specific emphasis on impulsive and inattentive behaviours. As these behaviours are believed to be associated with the frontostriatal circuit involving the nucleus accumbens (NAc) and the prefrontal cortex (PFC), the expression patterns of 8 genes (Comt, Drd2, Drd3, Drd4, Maoa, Sert, Tph1, and Tph2) from these two regions were examined. In addition, Golgi-Cox staining of medium spiny neurons in the NAc provided a neuroanatomical examination of mTBI-induced structural changes. The study found that a single early brain injury could induce impulsivity and impairments in response inhibition that were more pronounced in males. Interestingly, when animals with inherent impulsivity experienced mTBI, injury-related deficits were exacerbated in female animals. The single concussion increased dendritic branching, but reduced synaptic density in the NAc, and these changes were likely associated with the increase in impulsivity. Finally, mTBI-induced impulsivity was associated with modifications to gene expression that differed dramatically from the gene expression pattern associated with inherent impulsivity, despite very similar behavioural phenotypes. Our findings suggest the need to tailor treatment strategies for mTBI in light of an individual’s premorbid characteristics, given significant differences in molecular profiles of the frontostriatal circuits that depend upon sex and the etiology of the behavioural phenotype.     

Intraskeletal isotopic compositions (δ13C, δ15N) of bone collagen: Nonpathological and pathological variation

Paleodiet research traditionally interprets differences in collagen isotopic compositions (δ¹³C, δ¹⁵N) as indicators of dietary distinction even though physiological processes likely play some role in creating variation. This research investigates the degree to which bone collagen δ¹³C and δ¹⁵N values normally vary within the skeleton and examines the influence of several diseases common to ancient populations on these isotopic compositions. The samples derive from two medieval German cemeteries and one Swiss reference collection and include examples of metabolic disease (rickets/osteomalacia), degenerative joint disease (osteoarthritis), trauma (fracture), infection (osteomyelitis), and inflammation (periostitis). A separate subset of visibly nonpathological skeletal elements from the German collections established normal intraindividual variation. For each disease type, tests compared bone lesion samples to those near and distant to the lesions sites. Results show that normal (nonpathological) skeletons exhibit limited intraskeletal variation in carbon‐ and nitrogen‐isotope ratios, suggesting that sampling of distinct elements is appropriate for paleodiet studies. In contrast, individuals with osteomyelitis, healed fractures, and osteoarthritis exhibit significant intraskeletal differences in isotope values, depending on whether one is comparing lesions to near or to distant sites. Skeletons with periostitis result in significant intraskeletal differences in nitrogen isotope values only, while those with rickets/osteomalacia do not exhibit significant intraskeletal differences. Based on these results, we suggest that paleodiet researchers avoid sampling collagen at or close to lesion sites because the isotope values may be reflecting both altered metabolic processes and differences in diet relative to others in the population. Am J Phys Anthropol 153:598–604, 2014. © 2013 Wiley Periodicals, Inc.     

PCR-Denaturing Gradient Gel Electrophoresis of Complex Microbial Communities: A Two-Step Approach to Address the Effect of Gel-to-Gel Variation and Allow Valid Comparisons Across a Large Dataset

Denaturing gradient gel electrophoresis (DGGE) is widely used in microbial ecology to profile complex microbial communities over time and in response to different stimuli. However, inherent gel-to-gel variability has always been a barrier toward meaningful interpretation of DGGE profiles obtained from multiple gels. To address this problem, we developed a two-step methodology to align DGGE profiles across a large dataset. The use of appropriate inter-gel standards was of vital importance since they provided the basis for efficient within- and between-gel alignment and a reliable means to evaluate the final outcome of the process. Pretreatment of DGGE profiles by a commercially available image analysis software package (TL120 v2006, Phoretix 1D Advanced) followed by a simple interpolation step in Matlab minimized the effect of gel-to-gel variation, allowing for comparisons between large numbers of samples with a high degree of confidence. At the same time, data were obtained in the form of whole densitometric curves, rather than as band presence/absence or intensity information, and could be readily analyzed by a collection of well-established multivariate methods. This work clearly demonstrates that there is still room for significant improvements as to the way large DGGE datasets are processed and statistically interrogated.     

Myosin Vb is required for trafficking of the cystic fibrosis transmembrane conductance regulator in Rab11a-specific apical recycling endosomes in polarized human airway epithelial cells

Cystic fibrosis transmembrane conductance regulator (CFTR)-mediated Cl(-) secretion across fluid-transporting epithelia is regulated, in part, by modulating the number of CFTR Cl(-) channels in the plasma membrane by adjusting CFTR endocytosis and recycling. However, the mechanisms that regulate CFTR recycling in airway epithelial cells remain unknown, at least in part, because the recycling itineraries of CFTR in these cells are incompletely understood. In a previous study, we demonstrated that CFTR undergoes trafficking in Rab11a-specific apical recycling endosomes in human airway epithelial cells. Myosin Vb is a plus-end-directed, actin-based mechanoenzyme that facilitates protein trafficking in Rab11a-specific recycling vesicles in several cell model systems. There are no published studies examining the role of myosin Vb in airway epithelial cells. Thus, the goal of this study was to determine whether myosin Vb facilitates CFTR recycling in polarized human airway epithelial cells. Endogenous CFTR formed a complex with endogenous myosin Vb and Rab11a. Silencing myosin Vb by RNA-mediated interference decreased the expression of wild-type CFTR and DeltaF508-CFTR in the apical membrane and decreased CFTR-mediated Cl(-) secretion across polarized human airway epithelial cells. A recombinant tail domain fragment of myosin Vb attenuated the plasma membrane expression of CFTR by arresting CFTR recycling. The dominant-negative effect was dependent on the ability of the myosin Vb tail fragment to interact with Rab11a. Taken together, these data indicate that myosin Vb is required for CFTR recycling in Rab11a-specific apical recycling endosomes in polarized human airway epithelial cells.     

Acoustical expression of arousal in conflict situations in tree shrews (<Emphasis Type="Italic">Tupaia belangeri)</Emphasis>

Empirical research on human and non-human primates suggests that communication sounds express the intensity of an emotional state of a signaller. In the present study, we have examined communication sounds during induced social interactions of a monogamous mammal, the tree shrew. To signal their unwillingness to mate, female tree shrews show defensive threat displays towards unfamiliar males paralleled by acoustically variable squeaks. We assumed that the distance between interacting partners as well as the behavior of the male towards the female indicates the intensity of perceived social threat and thereby the arousal state of a female. To explore this hypothesis we analyzed dynamic changes in communication sounds uttered during induced social interactions between a female and an unfamiliar male. Detailed videographic and sound analyzes revealed that the arousal state predicted variations in communication sound structure reliably. Both, a decrease of distance and a male approaching the female led to an increase in fundamental frequency and repetition rate of syllables. These findings support comparable results in human and non-human primates and suggest that common coding rules in communication sounds govern acoustic conflict regulation in mammals.