Voluntary exercise training enhances glucose transport but not insulin signaling capacity in muscle of hypertensive TG(mREN2)27 rats.

Male heterozygous TG(mREN2)27 rats (TGR) overexpress a murine renin transgene, display marked hypertension, and have insulin resistance of skeletal muscle glucose transport and insulin signaling. We have shown previously that voluntary exercise training by TGR improves insulin-mediated skeletal muscle glucose transport (Kinnick TR, Youngblood EB, O'Keefe MP, Saengsirisuwan V, Teachey MK, and Henriksen EJ. J Appl Physiol 93: 805-812, 2002). The present study evaluated whether this training-induced enhancement of muscle glucose transport is associated with upregulation of critical insulin signaling elements, including insulin receptor substrate-1 (IRS-1), phosphatidylinositol 3-kinase, Akt, and glycogen synthase kinase-3. TGR remained sedentary or ran spontaneously in activity wheels for 6 wk, averaging 7.1 +/- 0.8 km/day by the end of week 3 and 4.3 +/- 0.5 km/day over the final week of training. Exercise training reduced total abdominal fat by 20% (P < 0.05) in TGR runners (2.64 +/- 0.01% of body weight) compared with sedentary TGR controls (3.28 +/- 0.01%). Insulin-stimulated (2 mU/ml) glucose transport activity in soleus muscle was 36% greater in TGR runners compared with sedentary TGR controls. However, the protein expression and functionality of tyrosine phosphorylation of insulin receptor and IRS-1, IRS-1 associated with the p85 regulatory subunit of phosphatidylinositol 3-kinase, and Ser473 phosphorylation of Akt were not altered by exercise training. Only insulin-stimulated glycogen synthase kinase-3beta Ser9 phosphorylation was increased (22%) by exercise training. These results indicate that voluntary exercise training in TGR can enhance insulin-mediated glucose transport in skeletal muscle, as well as reduce total abdominal fat mass. However, this adaptive response in muscle occurs independently of modifications in the proximal elements of the insulin signaling cascade.     

Seasonal dietary shifts enhance parasite transmission to lake salmonids during ice cover

Changes in abiotic and biotic factors between seasons in subarctic lake systems are often profound, potentially affecting the community structure and population dynamics of parasites over the annual cycle. However, few winter studies exist and interactions between fish hosts and their parasites are typically confined to snapshot studies restricted to the summer season whereas host‐parasite dynamics during the ice‐covered period rarely have been explored. The present study addresses seasonal patterns in the infections of intestinal parasites and their association with the diet of sympatric living Arctic charr (Salvelinus alpinus) and brown trout (Salmo trutta) in Lake Takvatn, a subarctic lake in northern Norway. In total, 354 Arctic charr and 203 brown trout were sampled from the littoral habitat between June 2017 and May 2018. Six trophically transmitted intestinal parasite taxa were identified and quantified, and their seasonal variations were contrasted with dietary information from both stomachs and intestines of the fish. The winter period proved to be an important transmission window for parasites, with increased prevalence and intensity of amphipod‐transmitted parasites in Arctic charr and parasites transmitted through fish prey in brown trout. In Arctic charr, seasonal patterns in parasite infections resulted mainly from temporal changes in diet toward amphipods, whereas host body size and the utilization of fish prey were the main drivers in brown trout. The overall dynamics in the community structure of parasites chiefly mirrored the seasonal dietary shifts of their fish hosts.     

Glycaemic and insulinemic response to dietary carbohydrates in horses

Background

Dietary sugar and starch affect plasma glucose and insulin concentrations. Little information is available about the effect of dietary fibre on plasma glucose and insulin concentration. It is hypothesized that different dietary fibre compositions will alter post-prandial glycaemic- and insulinemic index of test meals. The objective was to measure postprandial glucose and insulin concentrations in horses fed meals of different fibre compositions.

Methods

Blood was drawn via jugular vein puncture and the glycaemic and insulinemic index were calculated.

Results

The meal effect on glycaemic and insulinemic response followed the expected pattern, where plasma concentrations increased after feeding and declined after peak concentration. Glycaemic index was 100 (H), 102 (OB), 102 (BB) and 106 (M) and did not differ significantly between meals. Insulinemic index was 100 (H), 140 (OB), 121 (BB) and 125 (M) and did not differ significantly between meals.

Conclusions

In conclusion, meals containing different fibre compositions did not affect the glycaemic- and insulinemic index in horses.

     

Sources of uncertainty in assessment of marine phytoplankton communities

Characterisation of phytoplankton communities is important for classification of the ecological status of marine waters. In order to design a monitoring programme, it is important to know what degree of variation in the measurements occur at each level (water body, station and sample), so that resources can be spent in a way that maximise the precision of the measured parameters. Seven European water bodies were sampled to assess the variation in pigment concentrations and population densities attributed to water body, station and sample levels. It was found that the main proportion of the variation between pigment measurements was explained by the variation between stations (12–91% of variation) followed by the variation between water bodies (0–89% of variation). For measurements of population density, the main proportion of the variation between densities of cells recorded was explained by the variation between the taxonomists counting the samples (61%), whilst the main proportion of the variation between numbers of taxa recorded was explained by the variation between water bodies (83%). When the cell density of the nine dominant classes were analysed separately, the main proportion of variation was explained at the water body level for all but two class.     

Non‐GMO potato lines,synthesizing increased amylose and resistant starch,are mainly deficient in isoamylase debranching enzyme

Solanum tuberosum potato lines with high amylose content were generated by crossing with the wild potato species Solanum sandemanii followed by repeated backcrossing to Solanum tuberosum lines. The trait, termed increased amylose (IAm), was recessive and present after three generations of backcrossing into S. tuberosum lines (6.25% S. sandemanii genes). The tubers of these lines were small, elongated and irregular with small and misshaped starch granules and high sugar content. Additional backcrossing resulted in less irregular tuber morphology, increased starch content (4.3%–9.5%) and increased amylose content (29%–37.9%) but indifferent sugar content. The amylose in the IAm starch granules was mainly located in peripheral spots, and large cavities were found in the granules. Starch pasting was suppressed, and the digestion‐resistant starch (RS) content was increased. Comprehensive microarray polymer profiling (CoMPP) analysis revealed specific alterations of major pectic and glycoprotein cell wall components. This complex phenotype led us to search for candidate IAm genes exploiting its recessive trait. Hence, we sequenced genomic DNA of a pool of IAm lines, identified SNPs genome wide against the draft genome sequence of potato and searched for regions of decreased heterozygosity. Three regions, located on chromosomes 3, 7 and 10, respectively, displayed markedly less heterozygosity than average. The only credible starch metabolism‐related gene found in these regions encoded the isoamylase‐type debranching enzyme Stisa1. Decreased expression of mRNA (>500 fold) and reduced enzyme activity (virtually absent from IAm lines) supported Stisa1 as a candidate gene for IAm.     

Molecular analysis of hereditary nonpolyposis colorectal cancer in the United States: high mutation detection rate among clinically selected families and characterization of an American founder genomic deletion of the MSH2 gene

The identification of germline mutations in families with HNPCC is hampered by genetic heterogeneity and clinical variability. In previous studies, MSH2 and MLH1 mutations were found in approximately two-thirds of the Amsterdam-criteria-positive families and in much lower percentages of the Amsterdam-criteria-negative families. Therefore, a considerable proportion of HNPCC seems not to be accounted for by the major mismatch repair (MMR) genes. Does the latter result from a lack of sensitivity of mutation detection techniques, or do additional genes underlie the remaining cases? In this study we address these questions by thoroughly investigating a cohort of clinically selected North American families with HNPCC. We analyzed 59 clinically well-defined U.S. families with HNPCC for MSH2, MLH1, and MSH6 mutations. To maximize mutation detection, different techniques were employed, including denaturing gradient gel electrophoresis, Southern analysis, microsatellite instability, immunohistochemistry, and monoallelic expression analysis. In 45 (92%) of the 49 Amsterdam-criteria-positive families and in 7 (70%) of the 10 Amsterdam-criteria-negative families, a mutation was detected in one of the three analyzed MMR genes. Forty-nine mutations were in MSH2 or MLH1, and only three were in MSH6. A considerable proportion (27%) of the mutations were genomic rearrangements (12 in MSH2 and 2 in MLH1). Notably, a deletion encompassing exons 1-6 of MSH2 was detected in seven apparently unrelated families (12% of the total cohort) and was subsequently proven to be a founder. Screening of a second U.S. cohort with HNPCC from Ohio allowed the identification of two additional kindreds with the identical founder deletion. In the present study, we show that optimal mutation detection in HNPCC is achieved by combining accurate and expert clinical selection with an extensive mutation detection strategy. Notably, we identified a common North American deletion in MSH2, accounting for approximately 10% of our cohort. Genealogical, molecular, and haplotype studies showed that this deletion represents a North American founder mutation that could be traced back to the 19th century.     

The prevalent use of contraception among teenagers in Denmark and the corresponding low pregnancy rate

In Denmark the number of births and induced abortions among teenagers has reduced and teenage parenthood is now rare. This paper evaluates the correlation between this observed fertility and reported sexual and contraceptive behaviour. In 1989 a sample of 16-20-year-olds in Denmark was selected at random and personally interviewed about sexual and contraceptive behaviour. Ninety-five per cent of the young women who had experienced sexual intercourse used contraception at the most recent sexual intercourse. In order to support the validity of this finding a model was developed to estimate an expected number of conceptions in the age groups concerned. The model included both the information on coital frequency and use of contraception from the questionnaire and available efficacy rates on contraception. The estimates derived by the model were compared with the registered number of births and induced abortions derived from public registers. The analysis revealed a high accordance between the estimated number of conceptions and the registered number of births and induced abortions for each age group. This underlines the validity of the data on sexual and contraceptive behaviour sampled among teenagers in Denmark. The findings indicate that contraceptive failure is a much greater problem than non-use of contraception for teenagers in Denmark.     

Combined removal of nitrate and carbon in granular sludge: Substrate competition and activities

Granular sludge from an upflow anaerobic sludge blanket reactor treating synthetic waste water containing a mixture of volatile fatty acids and nitrate showed a removal efficiency of nearly 100% for both nitrogen and carbon. This activity was achieved by a combined process of denitrification and methanogenesis under conditions of surplus carbon. Under batch conditions the two processes proceeded clearly separated in time with first denitrification dominating and excluding methanogenesis. However, as soon as nitrate was depleted, methane production was initiated, showing that the inhibition of methanogenesis by nitrate was reversible. Of the volatile fatty acids supplied to the reactor, i.e. acetate, propionate, and butyrate, the denitrifying population clearly preferred butyrate and propionate even though acetate could also be metabolized. Consequently, growth of syntrophic volatile fatty acid degraders was suppressed by the denitrifiers in cases of low C:N ratios in the medium, leaving acetate as the major substrate for methanogenesis.Abbreviations UASB upflow anaerobic sludge blanket - COD chemical oxygen demand - VFA volatile fatty     

The Potential of a High Protein-Low Carbohydrate Diet to Preserve Intrahepatic Triglyceride Content in Healthy Humans

Background

Protein supplementation has been shown to reduce the increases in intrahepatic triglyceride (IHTG) content induced by acute hypercaloric high-fat and high-fructose diets in humans.

Objective

To assess the effect of a 12-wk iso-energetic high protein-low carbohydrate (HPLC) diet compared with an iso-energetic high carbohydrate-low protein (HCLP) diet on IHTG content in healthy non-obese subjects, at a constant body weight.

Design

Seven men and nine women [mean ± SD age: 24±5 y; BMI: 22.9±2.1 kg/m²] were randomly allocated to a HPLC [30/35/35% of energy (En%) from protein/carbohydrate/fat] or a HCLP (5/60/35 En%) diet by stratification on sex, age and BMI. Dietary guidelines were prescribed based on individual daily energy requirements. IHTG content was measured by ¹H-magnetic resonance spectroscopy before and after the dietary intervention.

Results

IHTG content changed in different directions with the HPLC (CH₂H₂O: 0.23±0.17 to 0.20±0.10; IHTG%: 0.25±0.20% to 0.22±0.11%) compared with the HCLP diet (CH₂H₂O: 0.34±0.20 vs. 0.38±0.21; IHTG%: 0.38±0.22% vs. 0.43±0.24%), which resulted in a lower IHTG content in the HPLC compared with the HCLP diet group after 12 weeks, which almost reached statistical significance (P = 0.055).

Conclusions

A HPLC vs. a HCLP diet has the potential to preserve vs. enlarge IHTG content in healthy non-obese subjects at a constant body weight.

Trial Registration

Clinicaltrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01551238","term_id":"NCT01551238"}}NCT01551238