Calcium-induced Ca2+ release from sarcoplasmic reticulum of pigs susceptible to malignant hyperthermia The effects of halothane and dantrolene

AbstractCalcium-induced calcium release and halothane-induced calcium release from pig sarcoplasmic reticulum (SR) were studied. The SR prepared from pig susceptible to malignant hyperthermia (MH) was shown to release calcium at a much lower level of calcium content than in normal pig SR. The concentration above which halothane can release calcium is 40 μM for both MH-SR and normal SR, although the latter required a high calcium content to demonstrate the calcium release. Dantrolene was shown to inhibit the halothane-induced calcium release. Results suggests that SR plays an importnat role in pathogenesis of MH

Reductive C−C Coupling from α,β‐Unsaturated Nitriles by Intercepting Keteniminates

We present an atom‐economic strategy to catalytically generate and intercept nitrile anion equivalents using hydrogen transfer catalysis. Addition of α,β‐unsaturated nitriles to a pincer‐based Ru−H complex affords structurally characterized κ‐N‐coordinated keteniminates by selective 1,4‐hydride transfer. When generated in situ under catalytic hydrogenation conditions, electrophilic addition to the keteniminate was achieved using anhydrides to provide α‐cyanoacetates in high yields. This work represents a new application of hydrogen transfer catalysis using α,β‐unsaturated nitriles for reductive C−C coupling reactions.An atom‐economic strategy to catalytically generate and intercept nitrile anion equivalents by hydrogen transfer catalysis has been developed. Addition of α,β‐unsaturated nitriles to a pincer‐based Ru−H complex affords keteniminates by selective 1,4‐hydride transfer, which were employed in a net hydrogenative acylation reaction.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149503/1/anie201904530.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149503/2/anie201904530-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149503/3/anie201904530_am.pd

Landfill gas generation and methane recovery at Naboro landfill, Fiji Islands: a case study from a developing Pacific Island country

The Naboro landfill in Suva, the capital city of Fiji Islands, is a sanitary engineered landfill, consisting of a compacted clay protective liner and leachate collection system. The waste is selectively placed, compacted and then covered with soil. The landfill was commisioned in 2005 and is currently receiving an average of 70,000 tonnes of waste annually. The municipal solid waste deposited in the landfill undergoes anaerobic decomposition and the methane gas generated escapes into the atmosphere, adding to the national greenhouse gas inventory. Currently there are no methane recovery and biogas utilisation technology in place or methane flaring at the Naboro landfill site. A feasibility study was carried out recently and based on the model output and field experiments, it was noted that methane recovery and utilisation could be a viable option although there could be some challenges associated with it. According to the waste chaacterization data supplied by the landfill operator it was noted that 83% is house hold waste, 11% is garden waste and 5% is food waste and 1% construction and demolition waste. Based on the type of waste deposited and the tropical weather condition it was calculated using the model that approximately 800 m3/h of methane is generated in 2016. Figure below shows the landfill gas generated at the Naboro landfill from stage 1 to stage 4. Due to tropical humid weather condition and waste rich is organic waste that decomposes rapidly results in the yearly average emission of 74% of total methane generated despite methane recovery via vertical wells installed at the end of each stage. The emission equates to 47,000 tons of CO2 equivalent per year despite methane recovery. The emission can be reduced if the methane generated could be extracted using vertical recovery wells half way through each stage rather than at the end of each stage and as a consequence a slight decrease in yearly average emissions of 41,000 tons of CO2 equivalent were noted. Another approach is to lay horizontal wells as the waste is compacted in the active cell and this could increase the efficiency of landfill gas extraction. The model result indicate that the use of horizontal wells reduces the yearly average emission to 55% of total methane generated. This highlights the fact that approximately 45 % of the methane generated could be harnessed and could be utilized to generate energy using gas engines. However a large fraction of the methane generated is still lost as emission to the atmopshere and this can be further reduced by enhancing the oxdising capacity of the soil cover. The methane oxidation in cover soil was measured to be 10.3% by measuring the CH4-CO2 ratios in the static chamber measurements. The experimental value is close to the IPCC default value of 10%. The paper will discuss other challenges associated with methane recovery at Naboro landfill particularly with landfill gas management

Cell-autonomous programming of rat adipose tissue insulin signalling proteins by maternal nutrition.

AIMS/HYPOTHESIS: Individuals with a low birthweight have an increased risk of developing type 2 diabetes mellitus in adulthood. This is associated with peripheral insulin resistance. Here, we aimed to determine whether changes in insulin signalling proteins in white adipose tissue (WAT) can be detected prior to the onset of impaired glucose tolerance, determine whether these changes are cell-autonomous and identify the underlying mechanisms involved. METHODS: Fourteen-month-old male rat offspring born to dams fed a standard protein (20%) diet or a low (8%) protein diet throughout gestation and lactation were studied. Fat distribution and adipocyte size were determined. Protein content and mRNA expression of key insulin signalling molecules were analysed in epididymal WAT and in pre-adipocytes that had undergone in vitro differentiation. RESULTS: The offspring of low protein fed dams (LP offspring) had reduced visceral WAT mass, altered fat distribution and a higher percentage of small adipocytes in epididymal WAT. This was associated with reduced levels of IRS1, PI3K p110β, Akt1 and PKCζ proteins and of phospho-Akt Ser473. Corresponding mRNA transcript levels were unchanged. Similarly, in vitro differentiated adipocytes from LP offspring showed reduced protein levels of IRβ, IRS1, PI3K p85α and p110β subunits, and Akt1. Levels of Akt Ser473 and IRS1 Tyr612 phosphorylation were reduced, while IRS1 Ser307 phosphorylation was increased. CONCLUSIONS/INTERPRETATION: Maternal protein restriction during gestation and lactation changes the distribution and morphology of WAT and reduces the levels of key insulin signalling proteins in the male offspring. This phenotype is retained in in vitro differentiated adipocytes, suggesting that programming occurs via cell-autonomous mechanism(s).This work was supported by Diabetes UK (MSM-G; no. 12/0004508), the British Heart Foundation (SEO; no. FS/09/029/27902) and the UK Medical Research Council (SEO; no. MC_UU_12012/4)This is the accepted manuscript. It is currently embargoed pending publication

Maternal protein restriction affects postnatal growth and the expression of key proteins involved in lifespan regulation in mice.

We previously reported that maternal protein restriction in rodents influenced the rate of growth in early life and ultimately affected longevity. Low birth weight caused by maternal protein restriction followed by catch-up growth (recuperated animals) was associated with shortened lifespan whereas protein restriction and slow growth during lactation (postnatal low protein: PLP animals) increased lifespan. We aim to explore the mechanistic basis by which these differences arise. Here we investigated effects of maternal diet on organ growth, metabolic parameters and the expression of insulin/IGF1 signalling proteins and Sirt1 in muscle of male mice at weaning. PLP mice which experienced protein restriction during lactation had lower fasting glucose (P = 0.038) and insulin levels (P = 0.046) suggesting improved insulin sensitivity. PLP mice had higher relative weights (adjusted by body weight) of brain (P = 0.0002) and thymus (P = 0.031) compared to controls suggesting that enhanced functional capacity of these two tissues is beneficial to longevity. They also had increased expression of insulin receptor substrate 1 (P = 0.021) and protein kinase C zeta (P = 0.046). Recuperated animals expressed decreased levels of many insulin signalling proteins including PI3 kinase subunits p85alpha (P = 0.018), p110beta (P = 0.048) and protein kinase C zeta (P = 0.006) which may predispose these animals to insulin resistance. Sirt1 protein expression was reduced in recuperated offspring. These observations suggest that maternal protein restriction can affect major metabolic pathways implicated in regulation of lifespan at a young age which may explain the impact of maternal diet on longevity

Altered PI3-kinase/Akt signalling in skeletal muscle of young men with low birth weight.

BACKGROUND: Low birth weight (LBW) is associated with increased future risk of insulin resistance and type 2 diabetes mellitus. The underlying molecular mechanisms remain poorly understood. We have previously shown that young LBW men have reduced skeletal muscle expression of PI3K p85alpha regulatory subunit and p110beta catalytic subunit, PKCzeta and GLUT4 in the fasting state. The aim of this study was to determine whether insulin activation of the PI3K/Akt and MAPK signalling pathways is altered in skeletal muscle of young adult men with LBW. METHODS: Vastus lateralis muscle biopsies were obtained from 20 healthy 19-yr old men with BW< or = 10th percentile for gestational age (LBW) and 20 normal birth weight controls (NBW), matched for physical fitness and whole-body glucose disposal, prior to (fasting state) and following a 4-hr hyperinsulinemic euglycemic clamp (insulin stimulated state). Expression and phosphorylation of selected proteins was determined by Western blotting. PRINCIPAL FINDINGS: Insulin stimulated expression of aPKCzeta (p<0.001) and Akt1 (p<0.001) was decreased in muscle of LBW men when compared to insulin stimulated controls. LBW was associated with increased insulin stimulated levels of IRS1 (p<0.05), PI3K p85alpha (p<0.001) and p110beta (p<0.05) subunits, while there was no significant change in these proteins in insulin stimulated control muscle. In addition LBW had reduced insulin stimulated phospho-Akt (Ser 473) (p<0.01), indicative of reduced Akt signalling. Insulin stimulated expression/phosphorylation of all the MAPK proteins studied [p38 MAPK, phospho-p38 MAPK (Thr180/Tyr182), phospho-ERK (Thr 202/Tyr204), JNK1, JNK2 and phospho-JNK (Thr 183/Tyr185)] was not different between groups. CONCLUSIONS: We conclude that altered insulin activation of the PI3K/Akt but not the MAPK pathway precedes and may contribute to development of whole-body insulin resistance and type 2 diabetes in men with LBW

Downregulation of IRS-1 in adipose tissue of offspring of obese mice is programmed cell-autonomously through post-transcriptional mechanisms.

We determined the effects of maternal diet-induced obesity on offspring adipose tissue insulin signalling and miRNA expression in the aetiology of insulin resistance in later life. Although body composition and glucose tolerance of 8-week-old male offspring of obese dams were not dysregulated, serum insulin was significantly (p<0.05) elevated. Key insulin signalling proteins in adipose tissue were down-regulated, including the insulin receptor, catalytic (p110β) and regulatory (p85α) subunits of PI3K as well as AKT1 and 2 (all p<0.05). The largest reduction observed was in IRS-1 protein (p<0.001), which was regulated post-transcriptionally. Concurrently, miR-126, which targets IRS-1, was up-regulated (p<0.05). These two features were maintained in isolated primary pre-adipocytes and differentiated adipocytes in-vitro. We have therefore established that maternal diet-induced obesity programs adipose tissue insulin resistance. We hypothesise that maintenance of the phenotype in-vitro strongly suggests that this mechanism is cell autonomous and may drive insulin resistance in later life

Effects of cortisol and dexamethasone on insulin signalling pathways in skeletal muscle of the ovine fetus during late gestation.

Before birth, glucocorticoids retard growth, although the extent to which this is mediated by changes in insulin signalling pathways in the skeletal muscle of the fetus is unknown. The current study determined the effects of endogenous and synthetic glucocorticoid exposure on insulin signalling proteins in skeletal muscle of fetal sheep during late gestation. Experimental manipulation of fetal plasma glucocorticoid concentration was achieved by fetal cortisol infusion and maternal dexamethasone treatment. Cortisol infusion significantly increased muscle protein levels of Akt2 and phosphorylated Akt at Ser473, and decreased protein levels of phosphorylated forms of mTOR at Ser2448 and S6K at Thr389. Muscle GLUT4 protein expression was significantly higher in fetuses whose mothers were treated with dexamethasone compared to those treated with saline. There were no significant effects of glucocorticoid exposure on muscle protein abundance of IR-β, IGF-1R, PKCζ, Akt1, calpastatin or muscle glycogen content. The present study demonstrated that components of the insulin signalling pathway in skeletal muscle of the ovine fetus are influenced differentially by naturally occurring and synthetic glucocorticoids. These findings may provide a mechanism by which elevated concentrations of endogenous glucocorticoids retard fetal growth

The Impact of Natural Ventilation During Winter on Thermal Comfort: A systematic literature review

The COVID-19 pandemic has highlighted the importance of ventilation as a transmission mitigation strategy. However, there is a widely-held concern that a drop in outdoor temperatures during wintertime may impact thermal comfort in the context of naturally ventilated classrooms. This is a concern which has not been widely investigated by peer-reviewed empirical studies. The aim of this paper is to review the available literature on the impact of natural ventilation during winter on thermal comfort. Using the replicable search processes of a systematic literature review adopted from medical research practice, 142 articles were retrieved from four search databases (Science direct, Scopus, PubMed, and Google Scholar). Analysis of these 142 articles revealed that most studies have particularly focused on the assessment of ventilation conditions, especially in non-naturally ventilated spaces, and that there were only 5 articles that empirically investigated the impact of natural ventilation on thermal comfort during winter in sufficient detail. This shows a significant gap within the body of literature, meaning that the findings from this study can only be treated as tentative, with further research required