The effect of ultrasound probe orientation on muscle architecture measurement.

The purpose of this paper was to examine how muscle architecture parameter (MAP) measurements made using brightness-mode ultrasonography (BMU) differ based on probe orientation. The human tibialis anterior muscle was imaged from nine different probe orientations during concentric contractions at four joint angles to determine the effect of probe orientation on the measurement of muscle architecture parameters. Ankle dorsi-flexion torque, tibialis anterior electromyography (EMG), and measures of MAP including fascicle length (FL), pennation angle (PA) and muscle thickness (MT) were collected. Statistically significant differences were found between joint angles for measures of FL and PA and between probe orientations for measures of FL and MT. A comparison of actual MAP values to a geometric model used by researchers to determine an ideal probe orientation show that the actual values vary to a greater extent and do not follow the trend predicted by the model. The results suggest that ultrasound probe orientation affects measures of MAP but the effect either cannot be predicted from a geometric model and/or the error in the measurement technique does not allow a comparison.     

Cryopreservation of epididymal dog sperm.

A method of cryopreservation was developed for sperm salvaged from the cauda epididymis and vas deferens of domestic dog testes. Four modifications of the glycerol concentration of a buffer used for cryopreservation of dog ejaculates and two freezing rates were assessed for their effect upon post-thaw spermatozoal motility and morphology. There was no statistical difference between the four glycerol concentrations or the two freezing rates and the buffer containing 6% glycerol and the freezing rate provided by 0.5 ml straws was chosen for further study. This method resulted in a significant reduction in the percentage of live spermatozoa detected with Hoechst staining and a reduction in the percentage of capacitated spermatozoa after freeze-thawing. However, there was no difference in the ability of frozen-thawed spermatozoa to penetrate homologous oocytes.This study demonstrates that cryopreservation of epididymal canine sperm can be performed using methods similar to those established for ejaculates of the same species, and that despite some damage, spermatozoa retain their functional ability.     

Microbial Dysbiosis Is Associated with Human Breast Cancer

Breast cancer affects one in eight women in their lifetime. Though diet, age and genetic predisposition are established risk factors, the majority of breast cancers have unknown etiology. The human microbiota refers to the collection of microbes inhabiting the human body. Imbalance in microbial communities, or microbial dysbiosis, has been implicated in various human diseases including obesity, diabetes, and colon cancer. Therefore, we investigated the potential role of microbiota in breast cancer by next-generation sequencing using breast tumor tissue and paired normal adjacent tissue from the same patient. In a qualitative survey of the breast microbiota DNA, we found that the bacterium Methylobacterium radiotolerans is relatively enriched in tumor tissue, while the bacterium Sphingomonas yanoikuyae is relatively enriched in paired normal tissue. The relative abundances of these two bacterial species were inversely correlated in paired normal breast tissue but not in tumor tissue, indicating that dysbiosis is associated with breast cancer. Furthermore, the total bacterial DNA load was reduced in tumor versus paired normal and healthy breast tissue as determined by quantitative PCR. Interestingly, bacterial DNA load correlated inversely with advanced disease, a finding that could have broad implications in diagnosis and staging of breast cancer. Lastly, we observed lower basal levels of antibacterial response gene expression in tumor versus healthy breast tissue. Taken together, these data indicate that microbial DNA is present in the breast and that bacteria or their components may influence the local immune microenvironment. Our findings suggest a previously unrecognized link between dysbiosis and breast cancer which has potential diagnostic and therapeutic implications.     

Human and Environmental Impacts on River Sediment Microbial Communities

Sediment microbial communities are responsible for a majority of the metabolic activity in river and stream ecosystems. Understanding the dynamics in community structure and function across freshwater environments will help us to predict how these ecosystems will change in response to human land-use practices. Here we present a spatiotemporal study of sediments in the Tongue River (Montana, USA), comprising six sites along 134 km of river sampled in both spring and fall for two years. Sequencing of 16S rRNA amplicons and shotgun metagenomes revealed that these sediments are the richest (∼65,000 microbial ‘species’ identified) and most novel (93% of OTUs do not match known microbial diversity) ecosystems analyzed by the Earth Microbiome Project to date, and display more functional diversity than was detected in a recent review of global soil metagenomes. Community structure and functional potential have been significantly altered by anthropogenic drivers, including increased pathogenicity and antibiotic metabolism markers near towns and metabolic signatures of coal and coalbed methane extraction byproducts. The core (OTUs shared across all samples) and the overall microbial community exhibited highly similar structure, and phylogeny was weakly coupled with functional potential. Together, these results suggest that microbial community structure is shaped by environmental drivers and niche filtering, though stochastic assembly processes likely play a role as well. These results indicate that sediment microbial communities are highly complex and sensitive to changes in land use practices.     

High Incidence of Diabetes after Stroke in Young Adults and Risk of Recurrent Vascular Events: The FUTURE Study

Background

Diabetes diagnosed prior to stroke in young adults is strongly associated with recurrent vascular events. The relevance of impaired fasting glucose (IFG) and incidence of diabetes after young stroke is unknown. We investigated the long-term incidence of diabetes after young stroke and evaluated the association of diabetes and impaired fasting glucose with recurrent vascular events.

Methods

This study was part of the FUTURE study. All consecutive patients between January 1, 1980, and November 1, 2010 with TIA or ischemic stroke, aged 18–50, were recruited. A follow-up assessment was performed in survivors between November 1, 2009 and January 1, 2012 and included an evaluation for diabetes, fasting venous plasma glucose and recurrent vascular events. The association of diabetes and IFG with recurrent vascular events was assessed by logistic regression analysis, adjusted for age, sex and follow-up duration.

Results

427 survivors without a medical history of diabetes were included in the present analysis (mean follow-up of 10.1 (SD 8.4) years; age 40.3 (SD 7.9) years). The incidence rate of diabetes was 7.9 per 1000 person-years and the prevalence of IFG was 21.1%. Patients with diabetes and IFG were more likely to have experienced any vascular event than those with normal fasting glucose values (OR 3.5 (95%CI 1.5–8.4) for diabetes and OR 2.5 (95%CI 1.3–4.8) for IFG).

Conclusions

Diabetes or IFG in young stroke survivors is frequent and is associated with recurrent vascular events. Regular screening for IFG and diabetes in this population, yields potential for secondary prevention.     

Positioning of APOBEC3G/F Mutational Hotspots in the Human Immunodeficiency Virus Genome Favors Reduced Recognition by CD8+ T Cells

Due to constitutive expression in cells targeted by human immunodeficiency virus (HIV), and immediate mode of viral restriction upon HIV entry into the host cell, APOBEC3G (A3G) and APOBEC3F (A3F) have been considered primarily as agents of innate immunity. Recent bioinformatic and mouse model studies hint at the possibility that mutation of the HIV genome by these enzymes may also affect adaptive immunity but whether this occurs in HIV-infected individuals has not been examined. We evaluated whether APOBEC-mediated mutations within common HIV CD8⁺ T cell epitopes can potentially enhance or diminish activation of HIV-specific CD8⁺ T cells from infected individuals. We compared ex vivo activation of CD8⁺ T lymphocytes from HIV-infected individuals by wild type HIV peptide epitopes and synthetic variants bearing simulated A3G/F-induced mutations by measuring interferon-γ (IFN-γ) production. We found that A3G/F-induced mutations consistently diminished HIV-specific CD8⁺ T cell responses against the common epitopes we tested. If this reflects a significant trend in vivo, then adaptation by HIV to enrich sequences that are favored for mutation by A3G/F (A3G/F hotspots) in portions of its genome that encode immunogenic CD8⁺ T cell epitopes would favor CTL escape. Indeed, we found the most frequently mutated A3G motif (CCC) is enriched up to 6-fold within viral genomic sequences encoding immunodominant CD8⁺ T cell epitopes in Gag, Pol and Nef. Within each gene, A3G/F hotspots are more abundant in sequences encoding epitopes that are commonly recognized due to their HLA restriction. Thus, in our system, mutations of the HIV genome, mimicking A3G/F activity, appeared to abrogate or severely reduce CTL recognition. We suggest that the physiological significance of this potential effect in facilitating CTL escape is echoed in the adaptation of the HIV genome to enrich A3G/F hotspots in sequences encoding CTL epitopes that are more immunogenic at the population level.     

The bioactivity and fractionation of peptide hydrolysates in cultures of CHO cells

Peptide hydrolysate supplements in mammalian cell cultures provide enhanced growth and productivity. The objective of this study was to compare the bioactivity of ten different commercially available hydrolysates from plant, microbial, and animal sources. The peptide hydrolysates were tested as supplements to cultures of Chinese hamster ovary (CHO) cells that produce human beta interferon (β‐IFN). A soy hydrolysate was shown to support high cell growth but not protein productivity compared to an animal component hydrolysate (Primatone RL). On the other hand, a yeast hydrolysate showed lower cell growth, but comparable productivity of the recombinant protein. Glycosylation analysis showed that the glycan profile of β‐IFN produced in yeast hydrolysate supplemented cultures was equivalent to that from Primatone RL‐supplemented cultures. Fractionation of the yeast hydrolysate and Primatone RL produced a similar protein‐assayed pattern except for one extra peak at around 1 kDa in the Primatone RL profile. A fraction taken at a molecular weight range of 1.5–1.7 kDa showed the highest growth promoting activity in both samples. However, four other fractions in yeast hydrolysate and two in Primatone RL at lower molecular weights showed some growth promoting activity. In conclusion, the yeast hydrolysates provided a good alternative to the animal sourced Primatone RL for high productivity of β‐IFN from CHO cells with equivalent glycosylation. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:584–593, 2014     

TAIMA (Stop) TB: The Impact of a Multifaceted TB Awareness and Door-to-Door Campaign in Residential Areas of High Risk for TB in Iqaluit,Nunavut

Background

The incidence rate of active tuberculosis (TB) disease in the Canadian Territory of Nunavut has shown a rising trend over the past 10 years. In 2010 it was 60 times greater than the national incidence rate. The objective of the Taima (translates to “stop” in Inuktitut) TB study was to implement and evaluate a public health campaign to enhance existing TB prevention efforts in Nunavut.

Methods

A TB awareness campaign followed by a door-to-door screening campaign was carried out in Iqaluit, Nunavut. The aim of the campaign was to raise awareness about TB, and to provide in-home screening and treatment for people living in residential areas at high risk for TB. Screening was based on geographic location rather than on individual risk factors.

Results

During the general awareness campaign an increase in the number of people who requested TB testing at the local public health clinic was observed. However, this increase was not sustained following cessation of the awareness campaign. Targeted TB screening in high risk residential areas in Iqaluit resulted in 224 individuals having TSTs read, and detection of 42 previously unidentified cases of latent TB, (overall yield of 18.8% or number needed to screen = 5.3). These cases of latent TB infection (LTBI) were extra cases that had not been picked up by traditional screening practices (34% relative increase within the community). This resulted in a 33% relative increase in the completion of LTBI treatment within the community. The program directly and indirectly identified 5/17 new cases of active TB disease in Iqaluit during the study period (29.5% of all incident cases).

Conclusions

While contact tracing investigations remain a cornerstone of TB prevention, additional awareness, screening, and treatment programs like Taima TB may contribute to the successful control of TB in Aboriginal communities.     

EGF activates its receptor by removing interactions that autoinhibit ectodomain dimerization

Epidermal growth factor (EGF) receptor is the prototype of the ErbB (HER) family receptor tyrosine kinases (RTKs), which regulate cell growth and differentiation and are implicated in many human cancers. EGF activates its receptor by inducing dimerization of the 621 amino acid EGF receptor extracellular region. We describe the 2.8 A resolution crystal structure of this entire extracellular region (sEGFR) in an unactivated state. The structure reveals an autoinhibited configuration, where the dimerization interface recently identified in activated sEGFR structures is completely occluded by intramolecular interactions. To activate the receptor, EGF binding must promote a large domain rearrangement that exposes this dimerization interface. This contrasts starkly with other RTK activation mechanisms and suggests new approaches for designing ErbB receptor antagonists.     

Estrogen, exercise, and the skeleton

Patterns of variation in bone size and shape provide crucial data for reconstructing hominin paleobiology, including ecogeographic adaptation, life history, and functional morphology. Measures of bone strength, including robusticity (diaphyseal thickness relative to length) and cross-sectional geometric properties such as moments of area, are particularly useful for inferring behavior because bone tissue adapts to its mechanical environment. Particularly during skeletal growth, exercise-induced strains can stimulate periosteal modeling so that, to some extent, bone thickness reflects individual behavior. Thus, patterns of skeletal robusticity have been used to identify gender-based activity differences, temporal shifts in mobility, and changing subsistence strategies. Although there is no doubt that mechanical loading leaves its mark on the skeleton, less is known about whether individuals differ in their skeletal responses to exercise. For example, the potential effects of hormones or growth factors on bone-strain interactions are largely unexplored. If the hormonal background can increase or decrease the effects of exercise on skeletal robusticity, then the same mechanical loads might cause different degrees of bone response in different individuals. Here I focus on the role of the hormone estrogen in modulating exercise-induced changes in human bone thickness.