Deletion of quinolinate phosphoribosyltransferase gene accelerates frailty phenotypes and neuromuscular decline with aging in a sex-specific pattern

Decline in neuromuscular function with aging is known to be a major determinant of disability and all-cause mortality in late life. Despite the importance of the problem, the neurobiology of age-associated muscle weakness is poorly understood. In a previous report, we performed untargeted metabolomics on frail older adults and discovered prominent alteration in the kynurenine pathway, the major route of dietary tryptophan degradation that produces neurotoxic intermediate metabolites. We also showed that neurotoxic kynurenine pathway metabolites are correlated with increased frailty score. For the present study, we sought to further examine the neurobiology of these neurotoxic intermediates by utilizing a mouse model that has a deletion of the quinolinate phosphoribosyltransferase (QPRT) gene, a rate-limiting step of the kynurenine pathway. QPRT^−/− mice have elevated neurotoxic quinolinic acid level in the nervous system throughout their lifespan. We found that QPRT^−/− mice have accelerated declines in neuromuscular function in an age- and sex-specific manner compared to control strains. In addition, the QPRT^−/− mice show premature signs of frailty and body composition changes that are typical for metabolic syndrome. Our findings suggest that the kynurenine pathway may play an important role in frailty and age-associated muscle weakness.     

Protective effects of melatonin against carbon tetrachloride-induced hepatotoxicity in rats: a light microscopic and biochemical study

The aim of this study was to examine the protective effects of melatonin against CCl4-induced hepatotoxicity in the rat. Twenty-four male Wistar rats were divided into three groups. Group I was used as a control. Rats in group II were injected every other day with CCl4 for 1 month, whereas rats in group III were injected every other day with CCl4 and melatonin for 1 month. At the end of the experiment, all animals were killed by decapitation and blood samples were obtained. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total and conjugated bilirubin levels were determined. For histopathological evaluation, livers of all rats were removed and processed for light microscopy. All serum biochemical parameters were significantly higher in animals treated with CCl4 than in the controls. When rats injected with CCl4 were treated with melatonin, significantly reduced elevations in serum biochemical parameters were found. In liver sections of the CCl4-injected group, necrosis, fibrosis, mononuclear cell infiltration, haemorrhage, fatty degeneration and formation of regenerative nodules were observed. Additionally, apoptotic figures, microvesicular steatosis and hydropic degeneration in hepatocytes were seen in this group. In contrast, the histopathological changes observed after administration of CCl4 were lost from rats treated with CCl4 and melatonin. Except for mild hydropic degeneration of the hepatocytes, a normal lobular appearance was seen in the livers of this group. The results of our study indicate that melatonin treatment prevents CCl4-induced liver damage in rats.     

Analysis of exponential growth data for yoghurt cultures

Obtaining accurate estimates of maximum specific growth rate, growth yield, and product yield is important for many fermentation processes. A systematic procedure is presented to select the exponential growth region and estimate the maximum specific growth rate using the covariate adjustment method with all the available measured variables (i.e. biomass, substrate, and product). The procedure is applied to data collected during growth of pure and mixed cultures of Lactobacillus bulgaricus and Streptococcus thermophilus on 3% dry milk under anaerobic conditions. The estimation procedure gives good estimates with relatively narrow confidence intervals even though biomass concentration is measured by an indirect method. The estimated values of maximum specific growth rate range from 0.2805 h(-1) for S. thermophilus (ATCC-19258) to 0.4672 h(-1) for S. thermophilus (Microlife). Growth and product yields are estimated using regression analysis and the data for the exponential growth region. The growth yields are compared to their theoretical maximum values.     

Anaerobic fermentation of Lactobacillus bulgaricus and streptococcus thermophilus on 3% nonfat dry milk with pure and mixed culture

Two different strains of Lactobacillus bulgaricus (ATCC-11842 and Microlife) and two strains of Streptococcus thermophilus (ATCC-19258 and Microlife) were grown anaerobically on 3% nonfat dry milk in pure and mixed culture using batch followed by fed batch culture. Samples were collected every 30 min. Concentrations of lactose, galactose, lactic acid, and other products present were measured using high pressure liquid chromatography. A spectrophotometric method from the literature was modified and used to determine microbial biomass concentrations. Relative cell numbers of the two organisms were measured microscopically in mixed culture. The results are presented in tabular form. S. thermophilus (Microlife) showed different growth characteristics compared to the other cultures. This culture utilized most of the galactose that was formed and produced greater amounts of lactic acid and biomass.     

Estimation of yield, maintenance, and product formation kinetic parameters in anaerobic fermentations

In many anaerobic fermentation processes, high energy bonds in adenosine triphosphate (ATP) are produced when available electrons are converted from organic substrate into extracellular organic products such as ethanol. The true growth yield and maintenance parameters are directly related to the product formation kinetic parameters for these anaerobic processes. Methods are presented which allow all of the experimental measurements to be used simultaneously to estimate these parameters. Results are presented for several different anaerobic fermentations.     

Anthropometric evaluation of the Creches children furniture in Turkey

The dimensions of the living and working space and buildings, the types of material and different riggings should be designed to conform to the users' anthropometric measures. The first requirement to design on ergonomic system is to measure the human being who will work and live in that system. Because of this, anthropometric measures are the most frequently used ergonomic data during the design process. In this research paper, we attempt to organize a new data base of anthropometric data to use in the design of children's equipment and furniture used in crèches. A starting point for research on the proper dimensions of creche furniture is to investigate how the dimensions of furniture reflect the body dimensions and the functional needs of the children using furniture. The anthropometric data of 3, 4 and 5 year-old-children in crèches was used. We report the results of the measurements of 18 anthropometric characteristics of children which constitute a set of basic data for the design of functional spaces and furniture.     

Tyrosinase inhibition studies of cycloartane and cucurbitane glycosides and their structure-activity relationships

In the present paper, tyrosinase inhibition studies and structure-activity relationship of eight cycloartane glycosides and one cucurbitane glycoside and its genin, which were isolated from Astragalus (Leguminoseae) and Bryonia (Cucurbitaceae) plants, have been discussed. The activities are compared with two reference tyrosinase inhibitors, kojic acid and l-mimosine. These studies and the SAR showed that the askendoside B which exhibited highly potent (IC50 =13.95 microM) tyrosinase inhibition could be a possible lead molecule for the development of new medications of several skin diseases related with the over-expression of the enzyme tyrosinase, like hyperpigmentation. The molecule also may be interesting for the cosmetic industries as a skin whitening agent.     

Stabilizing Role of Platelet P2Y12 Receptors in Shear-Dependent Thrombus Formation on Ruptured Plaques

Background

In most models of experimental thrombosis, healthy blood vessels are damaged. This results in the formation of a platelet thrombus that is stabilized by ADP signaling via P2Y₁₂ receptors. However, such models do not predict involvement of P2Y₁₂ in the clinically relevant situation of thrombosis upon rupture of atherosclerotic plaques. We investigated the role of P2Y₁₂ in thrombus formation on (collagen-containing) atherosclerotic plaques in vitro and in vivo, by using a novel mouse model of atherothrombosis.

Methodology

Plaques in the carotid arteries from Apoe ^−/− mice were acutely ruptured by ultrasound treatment, and the thrombotic process was monitored via intravital fluorescence microscopy. Thrombus formation in vitro was assessed in mouse and human blood perfused over collagen or plaque material under variable conditions of shear rate and coagulation. Effects of two reversible P2Y₁₂ blockers, ticagrelor (AZD6140) and cangrelor (AR-C69931MX), were investigated.

Principal Findings

Acute plaque rupture by ultrasound treatment provoked rapid formation of non-occlusive thrombi, which were smaller in size and unstable in the presence of P2Y₁₂ blockers. In vitro, when mouse or human blood was perfused over collagen or atherosclerotic plaque material, blockage or deficiency of P2Y₁₂ reduced the thrombi and increased embolization events. These P2Y₁₂ effects were present at shear rates >500 s⁻¹, and they persisted in the presence of coagulation. P2Y₁₂-dependent thrombus stabilization was accompanied by increased fibrin(ogen) binding.

Conclusions/Significance

Platelet P2Y₁₂ receptors play a crucial role in the stabilization of thrombi formed on atherosclerotic plaques. This P2Y₁₂ function is restricted to high shear flow conditions, and is preserved in the presence of coagulation.     

Regulation of the AGS3·Gαi Signaling Complex by a Seven-transmembrane Span Receptor

G-protein signaling modulators (GPSM) play diverse functional roles through their interaction with G-protein subunits. AGS3 (GPSM1) contains four G-protein regulatory motifs (GPR) that directly bind Gα_i free of Gβγ providing an unusual scaffold for the “G-switch” and signaling complexes, but the mechanism by which signals track into this scaffold are not well understood. We report the regulation of the AGS3·Gα_i signaling module by a cell surface, seven-transmembrane receptor. AGS3 and Gα_i1 tagged with Renilla luciferase or yellow fluorescent protein expressed in mammalian cells exhibited saturable, specific bioluminescence resonance energy transfer indicating complex formation in the cell. Activation of α₂-adrenergic receptors or μ-opioid receptors reduced AGS3-RLuc·Gα_i1-YFP energy transfer by over 30%. The agonist-mediated effects were inhibited by pertussis toxin and co-expression of RGS4, but were not altered by Gβγ sequestration with the carboxyl terminus of GRK2. Gα_i-dependent and agonist-sensitive bioluminescence resonance energy transfer was also observed between AGS3 and cell-surface receptors typically coupled to Gα_i and/or Gα_o indicating that AGS3 is part of a larger signaling complex. Upon receptor activation, AGS3 reversibly dissociates from this complex at the cell cortex. Receptor coupling to both Gαβγ and GPR-Gα_i offer additional flexibility for systems to respond and adapt to challenges and orchestrate complex behaviors.