The effect of glucocorticoids on the myosin heavy chain isoforms' turnover in skeletal muscle

The purpose of this study was to find the effect of dexamethasone on the myosin heavy chain (MyHC) isoforms' composition in different skeletal muscles and glycolytic (G) fibres in relation with their synthesis rate and degradation of MyHC isoforms by alkaline proteinases. Eighteen-week-old male rats of the Wistar strain were treated with dexamethasone (100 microg/100 g bwt) during 10 days. The forelimb strength decreased from 9.52 to 6.19 N (P<0.001) and hindlimb strength from 15.54 to 8.55 N (P<0.001). Daily motor activity decreased (total activity from 933 to 559 and ambulatory activity from 482 to 226 movements/h, P<0.001). The degradation rate of muscle contractile proteins increased from 2.0 to 5.9% per day (P<0.001), as well as the myosin heavy chain IIB isoform degradation with alkaline proteinase in fast-twitch (F-T) muscles (12 +/- 0.9%; P<0.05) and glycolytic muscle fibres (15 +/- 1.1%; P<0.001). The synthesis rate of MyHC type II isoforms decreased in Pla muscles (P<0.05) and MyHC IIA (P<0.05) and IIB in EDL muscle and G fibres (P<0.001). The relative content of MyHC IIB isoform decreased in F-T muscles (P<0.001) and in G fibres (P<0.01), and the relative content of IIA and IID isoforms increased simultaneously. Dexamethasone decreased the MyHC IIB isoform synthesis rate and increased the sensibility of MyHC IIB isoform to alkaline proteinase, which in its turn led to the decrease of MyHC IIB isoform relative content in F-T muscles with low oxidative potential and G muscle fibres.     

Effect of glucocorticoids on contractile apparatus of rat skeletal muscle

Skeletal muscles which have a high oxidative potential are less sensitive to the catabolic action of dexamethasone. In fast-twitch white muscles, where the oxidative capacity is low, the alkaline proteinase activity as well as the rise in the number of lysosomes was more pronounced. It seems that the glucocorticoid-caused myopathy is a result of elevated degradation of contractile proteins. This process of degradation of contractile proteins begins in the myosine filaments and then spreads to the thin filaments and the z-line.     

Comparison of the selenium level with GSH-Px activity in the liver of mice treated with 7,12 DMBA

In this study, the relationship between selenium (Se) and glutathione peroxidase (GSHPx) levels was investigated in 7,12-dimethylbenz(a)anthracene (7,12-DMBA)-treated mouse liver. The potential mammary carcinogen 7,12-DMBA, was injected intraperitoneally (20 mg kg(-1) day(-1)) into 10-12 month old female mice. After 21 days of application the mice were sacrificed and GSHPx and Se levels of liver homogenates were measured. Se and GSHPx levels in 7,12-DMBA-treated mice were significantly lower than those of controls (p < 0.05). The control group exhibited 0.9 +/- 0.066 U mg(-1) protein and 0.86 +/- 0.058 p.p.m. levels of GSHPx and Se respectively. The 7,12-DMBA-treated group had significantly (p < 0.05) decreased GSHPx and Se levels (0.42 +/- 0.062 U mg(-1) protein and 0.69 +/- 0.034 p.p.m. respectively). The results show a direct relationship between Se and GSHPx activity and a negative correlation between antioxidant capacity and existence of a carcinogen in metabolism.     

Effects of chronic REM sleep deprivation on lipocalin-2, nitric oxide synthase-3, interleukin-6 and cardiotrophin-1 levels: an experimental rat model

Sleep and Biological Rhythms - The purpose of this study was to investigate the effects of chronic rapid eye movement sleep deprivation on cardiovascular system using blood levels of lipocalin-2,...     

Determining <Emphasis Type="Italic">Candida</Emphasis> spp. Incidence in Denture Wearers

The aim of this study was to determine Candida spp. incidence in the oral cavity of denture wearers and characterize predisposing factors in denture-related stomatitis (DRS). Three groups of denture wearers and a control group were evaluated for DRS according to Newton’s classification. The amount of yeast in saliva and the presence of yeast on mucosal surfaces were determined by phenotyping methods, and the impact of some risk factors on candidal carriage was evaluated. The development of DRS is most common in complete prosthesis users. When the count of yeast in saliva is ≥400 cfu/ml, the frequency of DRS is increased. In individuals who develop DRS, the most frequently encountered species that was identified as C. albicans. Prosthetic hygiene was related to the intensity of candidal growth and the development of DRS. C. albicans live as saprophyte in the oral cavity. But, it is capable of causing infection if there are predisposing conditions related to the host. Usage of removable prosthesis may cause these microorganisms to gain pathogenicity.     

Discovery of mutations in Saccharomyces cerevisiae by pooled linkage analysis and whole-genome sequencing

Many novel and important mutations arise in model organisms and human patients that can be difficult or impossible to identify using standard genetic approaches, especially for complex traits. Working with a previously uncharacterized dominant Saccharomyces cerevisiae mutant with impaired vacuole inheritance, we developed a pooled linkage strategy based on next-generation DNA sequencing to specifically identify functional mutations from among a large excess of polymorphisms, incidental mutations, and sequencing errors. The VAC6-1 mutation was verified to correspond to PHO81-R701S, the highest priority candidate reported by VAMP, the new software platform developed for these studies. Sequence data further revealed the large extent of strain background polymorphisms and structural alterations present in the host strain, which occurred by several mechanisms including a novel Ty insertion. The results provide a snapshot of the ongoing genomic changes that ultimately result in strain divergence and evolution, as well as a general model for the discovery of functional mutations in many organisms.     

A Case Discussion on Market‐Based Extended Producer Responsibility: The Minnesota Electronics Recycling Act

In this article, we analyze the Minnesota Electronics Recycling Act to explore the benefits and potential drawbacks of a market‐based extended producer responsibility (EPR) legislation implementation with operational flexibility for manufacturers. Based on publicly available reports and stakeholder interviews, we find that the Minnesota Act attains two key goals of market‐based EPR (i.e., higher cost efficiencies and substantial landfill diversion); however, this may come at the expense of selective collection and recycling, an increased burden on local governments, and a loss of balance in contractual power between stakeholders. We observe that these concerns arise because of specific flexibility provisions afforded to manufacturers that allow them to operationalize their EPR compliance with a cost‐efficiency focus. Thus, we conclude that EPR goals must be carefully translated into operating rules in order to achieve goals while avoiding unintended consequences.     

Identification of region-specific genes in the early chicken endoderm

In vertebrates, the endoderm gives rise to the epithelial lining of the digestive tract, respiratory system and endocrine organs. After gastrulation, the newly formed endoderm gradually becomes regionalized and differentiates into specific organs. To understand the molecular basis of early endoderm regionalization, which is largely unknown, it is necessary to identify novel region-specific genes as candidates potentially involved in this process. Applying an Affymetrix Array based approach we aimed for the identification of genes specifically upregulated in the foregut or mid-/hindgut endoderm at the onset of regionalization. Several genes exhibiting spatial and temporal restricted expression patterns in the developing early endoderm were identified and their expression was validated via RT-PCR and whole mount in situ hybridization. We report here the detailed gene expression patterns of two novel genes specifically associated with foregut endoderm and of eight novel genes specifically expressed in the mid-/hindgut endoderm at HH stages 10-11. Future functional analysis of these genes may help to elucidate the mechanisms involved in endoderm development and regionalization.