Leucine-rich diet supplementation modulates foetal muscle protein metabolism impaired by Walker-256 tumour

Background

Cancer-cachexia induces a variety of metabolic disorders of protein turnover and is more pronounced when associated with pregnancy. Tumour-bearing pregnant rats have impaired protein balance, which decreases protein synthesis and increases muscle breakdown. Because branched-chain amino acids, especially leucine, stimulate protein synthesis, we investigated the effect of a leucine-rich diet on protein metabolism in the foetal gastrocnemius muscles of tumour-bearing pregnant rats.

Methods

Foetuses of pregnant rats with or without Walker 256 tumours were divided into six groups. During the 20 days of the experiment, the pregnant groups were fed with either a control diet (C, control rats; W, tumour-bearing rats; Cp, rats pair-fed the same normoprotein-diet as the W group) or with a leucine-rich diet (L, leucine rats; LW, leucine tumour-bearing rats; and Lp, rats pair-fed the same leucine-rich diet as the LW group). After the mothers were sacrificed, the foetal gastrocnemius muscle samples were resected, and the protein synthesis and degradation and tissue chymotrypsin-like, cathepsin and calpain enzyme activities were assayed. The muscle oxidative enzymes (catalase, glutathione-S-transferase and superoxide dismutase), alkaline phosphatase enzyme activities and lipid peroxidation (malondialdehyde) were also measured.

Results

Tumour growth led to a reduction in foetal weight associated with decreased serum protein, albumin and glucose levels and low haematocrit in the foetuses of the W group, whereas in the LW foetuses, these changes were less pronounced. Muscle protein synthesis (measured by L-[3H]-phenylalanine incorporation) was reduced in the W foetuses but was restored in the LW group. Protein breakdown (as assessed by tyrosine release) was enhanced in the L and W groups, but chymotrypsin-like activity increased only in group W and tended toward an increase in the LW foetuses. The activity of cathepsin H was significantly higher in the W group foetuses, but the proteolytic calcium-dependent pathway showed similar enzyme activity. In parallel, an intense oxidative stress process was observed only in the group W foetuses.

Conclusions

These data suggested that the proteasomal and lysosomal proteolytic pathways and oxidative stress are likely to participate in the process of foetal muscle catabolism of Walker’s tumour-bearing pregnant rats. The present work shows that foetal muscle can be protected by supplementation with a leucine-rich diet.     

The Deuterator: software for the determination of backbone amide deuterium levels from H/D exchange MS data

Background  

The combination of mass spectrometry and solution phase amide hydrogen/deuterium exchange (H/D exchange) experiments is an effective method for characterizing protein dynamics, and protein-protein or protein-ligand interactions. Despite methodological advancements and improvements in instrumentation and automation, data analysis and display remains a tedious process. The factors that contribute to this bottleneck are the large number of data points produced in a typical experiment, each requiring manual curation and validation, and then calculation of the level of backbone amide exchange. Tools have become available that address some of these issues, but lack sufficient integration, functionality, and accessibility required to address the needs of the H/D exchange community. To date there is no software for the analysis of H/D exchange data that comprehensively addresses these issues.     

Hes1 Increases the Invasion Ability of Colorectal Cancer Cells via the STAT3-MMP14 Pathway

The Notch pathway contributes to self-renewal of tumor-initiating cell and inhibition of normal colonic epithelial cell differentiation. Deregulated expression of Notch1 and Jagged1 is observed in colorectal cancer. Hairy/enhancer of split (HES) family, the most characterized targets of Notch, involved in the development of many cancers. In this study, we explored the role of Hes1 in the tumorigenesis of colorectal cancer. Knocking down Hes1 induced CRC cell senescence and decreased the invasion ability, whereas over-expression of Hes1 increased STAT3 phosphorylation activity and up-regulated MMP14 protein level. We further explored the expression of Hes1 in human colorectal cancer and found high Hes1 mRNA expression is associated with poor prognosis in CRC patients. These findings suggest that Hes1 regulates the invasion ability through the STAT3-MMP14 pathway in CRC cells and high Hes1 expression is a predictor of poor prognosis of CRC.     

Generation and characterization of human insulin-releasing cell lines

Background  

The in vitro culture of insulinomas provides an attractive tool to study cell proliferation and insulin synthesis and secretion. However, only a few human beta cell lines have been described, with long-term passage resulting in loss of insulin secretion. Therefore, we set out to establish and characterize human insulin-releasing cell lines.     

A molecular basis for the physiological variation in shade avoidance responses: A tale of two ecotypes

Using two ecotypes of Stellaria longipes with contrasting responses to shade, we found that plants can differ in their responses to similar light cues, reflecting adaptations to their natural habitat. It was also observed that the plants could distinguish between distinct shade signals. Furthermore, the activity of wall modifying proteins, expansins and xyloglucan endotransglucosylase/hydrolase(s) (XTHs) was regulated during these responses. However, only expansin activity and gene expression profiles correlated with observed growth trends. The differential expression of expansins was light signal specific and ecotype specific and could account for both the trends in growth and their magnitude. We have thus established a potential molecular basis for the observed plasticity in responses to shade.Key words: shade avoidance, cell wall modification, expansins, XTHs, Stellaria longipes, phenotypic plasticity, light quality     

The activation of Rac1 by M3 muscarinic acetylcholine receptors involves the translocation of Rac1 and IQGAP1 to cell junctions and changes in the composition of protein complexes containing Rac1, IQGAP1, and actin

The abilities of the M(3) muscarinic acetylcholine receptor (mAChR) and Rac1 to regulate similar cellular responses, including cadherin-mediated adhesion, prompted us to investigate Rac1 regulation by M(3) mAChR. We characterized changes in Rac1 induced by stimulating transfected M(3) mAChR in Chinese hamster ovary cells stably expressing hemagglutinin (HA)-tagged wild-type or mutant Rac1. mAChR activation converts endogenous Rac1 to the GTP-bound form in cells expressing HA-Rac1 but not in cells expressing dominant negative HA-Rac1(Asn-17) or constitutively active HA-Rac1(Val-12). The competitive binding of endogenous IQGAP1 by HA-Rac1(Val-12) may diminish the mAChR-mediated activation of endogenous Rac1. HA-Rac1 and HA-Rac1(Val-12), but not HA-Rac1(Asn-17), accumulate with IQGAP1 at cell junctions during mAChR-induced cell-cell compaction. Co-localization studies suggest that Rac1 can accumulate at junctions without IQGAP1, but IQGAP1 cannot accumulate at junctions without Rac1. mAChR activation also induces GTP-independent changes in Rac1 because mAChR activation redistributes HA-Rac1(Asn-17), which does not bind GTP. Actin associates with complexes containing HA-Rac1 or HA-Rac1(Val-12) after prolonged mAChR activation. We also demonstrate that Rac1 participates in mAChR-induced cell-cell compaction and c-Jun phosphorylation. These results indicate that M(3) mAChR activation converts Rac1 to the GTP-bound form, alters interactions between Rac1, IQGAP1, and actin, and causes the junctional accumulation of Rac1 and IQGAP1.     

Glass micromodel study of bacterial dispersion in spatially periodic porous networks

Successful implementation of bioremediation clean-up strategies depends on accurate predictions of the transport of bacteria within the subsurface. In this study, etched flat-plate glass micromodels were used to examine bacterial transport in a homogenous network. These networks were created by acid-etching interconnected channels into a glass plate and then fusing it to an unetched plate forming semi-cylindrical pores. The transparent nature of the micromodel allows for both qualitative observations of the bacteria within the pores and quantitative measurements of their concentration. The micromodels are designed to allow establishment of a well-characterized step change in bacterial concentration (Escherichia coli NR50) within the network. During the experiments, bacteria are dispersed through the network by flow. Light scattering is used to detect the change in turbidity within the pores as the bacteria travel through the network. The change in turbidity is used to construct breakthrough curves and spatial concentration profiles of bacteria within the network. The breakthrough curves are fit to the one-dimensional advection/dispersion equation to determine dispersion coefficients at different interstitial fluid velocities. From the breakthrough curves, dispersion coefficients were reproducible for replicate experiments over a range of velocities in the advection-dominated regime. The dispersivity values for two network designs resembling an interconnecting capillary network and a spatially periodic network of cylinders were 0.28 and 0.33 cm respectively, which are slightly greater than the literature values found for other pore networks. Experiments were also conducted within the diffusion-dominated regime to examine the effects of bacterial motility on dispersion. The accumulation of bacteria on the pore walls became significant at the low flow rates and extended experimental times thereby rendering the use of light scattering to determine concentrations ineffective. Bacterial chemotaxis, created by a self-imposed oxygen gradient, was also observed in the micromodel under stagnant fluid conditions.     

Salmonella and campylobacter contamination of broiler chicken carcasses and scald tank water: the influence of water pH

Scalding at 50°± 0.5°C, in water maintained at pH 9.0 ± 0.2 by the addition of sodium hydroxide, had no effect on the incidence of salmonella or campylobacter contamination of chicken carcasses. There were significant reductions, however, in the numbers of these organisms in the water itself.     

Second malignant neoplasms after cancer in childhood or adolescence. Nordic Society of Paediatric Haematology and Oncology Association of the Nordic Cancer Registries.

OBJECTIVE--To assess the relative risk of developing a second malignant neoplasm in people with a diagnosis of cancer in childhood and adolescence. DESIGN--Register based follow up study. SETTING--Populations of Nordic countries. SUBJECTS--30,880 people under the age of 20 with a first malignant neoplasm diagnosed during the period 1943-87. MAIN OUTCOME MEASURES--Relative and attributable risks of second malignant neoplasms by type of first cancer, age at first diagnosis, calendar period, sex, and country. Expected figures were based on the appropriate national incidence rates for cancer. RESULTS--247 cases of second malignant neoplasms were observed in 238 patients, yielding a relative risk for cancer of 3.6 (95% confidence interval 3.1 to 4.1). The risk changed significantly from 2.6 in people first diagnosed during the 1940s and 1950s to 6.9 among cohort members included in the late 1970s and 1980s. Increases were observed for most types of cancer. Highest levels of the relative risk were seen during the 10 years immediately after first malignant diagnosis. The incidence of second malignant neoplasms attributable to the first cancer and associated treatments, however, showed a consistent rise throughout the 45 years of follow up. CONCLUSION--The estimated risks for a second malignant neoplasm were significantly lower than those found in most large hospital based studies but compatible with the results from a similar population based study in the United Kingdom. Extent of risk and cancer pattern were similar among the Nordic countries and are believed to be representative for a large part of the European population.