Effect of genotype on duodenal expression of nutrient transporter genes in dairy cows

peer-reviewedBackground Studies have shown clear differences between dairy breeds in their feed intake and production efficiencies. The duodenum is critical in the coordination of digestion and absorption of nutrients. This study examined gene transcript abundance of important classes of nutrient transporters in the duodenum of non lactating dairy cows of different feed efficiency potential, namely Holstein-Friesian (HF), Jersey (JE) and their F1 hybrid. Duodenal epithelial tissue was collected at slaughter and stored at -80°C. Total RNA was extracted from tissue and reverse transcribed to generate cDNA. Gene expression of the following transporters, namely nucleoside; amino acid; sugar; mineral; and lipid transporters was measured using quantitative real-time RT-PCR. Data were statistically analysed using mixed models ANOVA in SAS. Orthogonal contrasts were used to test for potential heterotic effects and spearman correlation coefficients calculated to determine potential associations amongst gene expression values and production efficiency variables. Results While there were no direct effects of genotype on expression values for any of the genes examined, there was evidence for a heterotic effect (P < 0.05) on ABCG8, in the form of increased expression in the F1 genotype compared to either of the two parent breeds. Additionally, a tendency for increased expression of the amino acid transporters, SLC3A1 (P = 0.072), SLC3A2 (P = 0.081) and SLC6A14 (P = 0.072) was also evident in the F1 genotype. A negative (P < 0.05) association was identified between the expression of the glucose transporter gene SLC5A1 and total lactational milk solids yield, corrected for body weight. Positive correlations (P < 0.05) were also observed between the expression values of genes involved in common transporter roles. Conclusion This study suggests that differences in the expression of sterol and amino acid transporters in the duodenum could contribute towards the documented differences in feed efficiency between HF, JE and their F1 hybrid. Furthermore, positive associations between the expression of genes involved in common transporter roles suggest that these may be co-regulated. The study identifies potential candidates for investigation of genetic variants regulating nutrient transport and absorption in the duodenum in dairy cows, which may be incorporated into future breeding programmes

A Gel Probe Equilibrium Sampler for Measuring Arsenic Porewater Profiles and Sorption Gradients in Sediments: I. Laboratory Development

A gel probe equilibrium sampler has been developed to study arsenic (As) geochemistry and sorption behavior in sediment porewater. The gels consist of a hydrated polyacrylamide polymer, which has a 92% water content. Two types of gels were used in this study. Undoped (clear) gels were used to measure concentrations of As and other elements in sediment porewater. The polyacrylamide gel was also doped with hydrous ferric oxide (HFO), an amorphous iron (Fe) oxyhydroxide. When deployed in the field, HFO-doped gels introduce a fresh sorbent into the subsurface thus allowing assessment of in situ sorption. In this study, clear and HFO-doped gels were tested under laboratory conditions to constrain the gel behavior prior to field deployment. Both types of gels were allowed to equilibrate with solutions of varying composition and re-equilibrated in acid for analysis. Clear gels accurately measured solution concentrations (±1%), and As was completely recovered from HFO-doped gels (±4%). Arsenic speciation was determined in clear gels through chromatographic separation of the re-equilibrated solution. For comparison to speciation in solution, mixtures of As(III) and As(V) adsorbed on HFO embedded in gel were measured in situ using X-ray absorption spectroscopy (XAS). Sorption densities for As(III) and As(V) on HFO embedded in gel were obtained from sorption isotherms at pH 7.1. When As and phosphate were simultaneously equilibrated (in up to 50-fold excess of As) with HFO-doped gels, phosphate inhibited As sorption by up to 85% and had a stronger inhibitory effect on As(V) than As(III). Natural organic matter (>200 ppm) decreased As adsorption by up to 50%, and had similar effects on As(V) and As(III). The laboratory results provide a basis for interpreting results obtained by deploying the gel probe in the field and elucidating the mechanisms controlling As partitioning between solid and dissolved phases in the environment

Microbial Biosafety of Pilot-scale Bioreactor Treating MTBE and TBA-contaminated Drinking Water Supply

A pilot-scale sand-based fluidized bed bioreactor (FBBR) was utilized to treat both methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) from a contaminated aquifer. To evaluate the potential for re-use of the treated water, we tested for a panel of water quality indicator microorganisms and potential waterborne pathogens including total coliforms, Escherichia coli, Salmonella and Shigella spp., Campylobacter jejuni, Aeromonas hydrophila, Legionella pneumophila, Vibrio cholerae, Yersinia enterocolytica and Mycobacterium avium in both influent and treated waters from the bioreactor. Total bacteria decreased during FBBR treatment. E. coli, Salmonella and Shigella spp., C. jejuni, V. cholerae, Y. enterocolytica and M. avium were not detected in aquifer water or bioreactor treated water samples. For those pathogens detected, including total coliforms, L. pneumophila and A. hydrophila, numbers were usually lower in treated water than influent samples, suggesting removal during treatment. The detection of particular bacterial species reflected their presence or absence in the influent waters

Clinical Pathways to Disability

This paper examines the pathways by which individuals transition from healthy to disabled. Because of the high prevalence and costs associated with disability, understanding these pathways is critical to developing interventions to prevent or minimize disability. We compare two estimates of disabling conditions: those observed in medical claims and conditions indicated by the disabled individual. A small number of conditions explain about half of incident disability: arthritis, infectious disease, dementia, heart failure, diabetes, and stroke. These conditions show up in medical claims and self reports. A large number of elderly also attribute disability to old age and various symptoms. Because so many of the most disabling conditions do not have clear medical treatments, the outlook for major reductions in disability might be limited.

How Do the Better Educated Do It? Socioeconomic Status and the Ability to Cope with Underlying Impairment

There is a pronounced gradient in disability across socioeconomic groups, with better educated and higher income groups reporting substantially less disability. In this paper, we consider why that is the case, focusing on impairments in basic physical and cognitive aspects of living for the elderly. Our empirical work has two parts. First, we consider how much of this gradient in disability is a result of underlying differences in functioning versus the ability to cope with impairments. We show differences in functioning are the major part of the difference in disability, but both are important. Second, we consider how the better educated elderly cope with disability. Better educated people use substantially more assistive technology than the less educated and are more likely to use paid help. But use of these services is not the primary reason that the better educated are better able to cope. We conclude with thoughts about other potential factors that may explain differential coping.

Intensive Medical Care and Cardiovascular Disease Disability Reductions

There is little empirical evidence to explain why disability declined among the elderly over the past 20 years. In this paper, we explore the role of improved medical care for cardiovascular disease on health status improvements over time. We show that the incidence of cardiovascular disease hospitalizations remained relatively constant between 1984 and 1999 at the same time that post-event survival improved and disability declined. We find that use of appropriate therapies, including pharmaceuticals such as beta-blockers, aspirin, and ace-inhibitors, and invasive procedures, explains up to 50% and 70% of the reductions in disability and death over time, respectively. Elderly patients living in regions with high use of appropriate medical therapies had better health outcomes than patients living in low-use areas. Finally, we estimate that preventing disability after an acute event can add as much as 3.7 years of quality-adjusted life expectancy, or $316,000 of value.