Confined compression of collagen hydrogels

Reconstituted collagen hydrogels are often used for in vitro studies of cell-matrix interaction and as scaffolds for tissue engineering. Understanding the mechanical and transport behaviours of collagen hydrogels is therefore extremely important, albeit difficult due to their very high water content (typically > 99.5%). In the present study the mechanical behaviour of collagen hydrogels in confined compression was investigated using biphasic theory (J. Biomech. Eng. 102 (1980) 73), to ascertain whether the technique is sufficiently sensitive to determine differences in the characteristics of hydrogels of between 0.2% and 0.4% collagen. Peak stress, equilibrium stress, aggregate modulus and hydraulic permeability of the hydrogels exhibited sensitivity to collagen content, demonstrating that the technique is clearly able to discriminate between hydrogels with small differences in collagen content and may also be sensitive to factors that affect matrix remodelling. The results also offer additional insight into the deformation-dependent permeability of collagen hydrogels. This study suggests that confined compression, together with biphasic theory, is a suitable technique for assessing the mechanical properties of collagen hydrogels

Construction Cost Sensitivity of a Lignocellulosic Ethanol Biorefinery

The technology has been developed to convert feedstock with cellulose content into ethanol. However, ethanol produced from cellulosic feedstock is the same as ethanol distilled from grain. The objective of research is to determine the price per gallon of ethanol needed so that producing lignocellulosic based ethanol become economically feasible.Environmental Economics and Policy, Production Economics,

Acute coronary syndrome in the older adults

Coronary heart disease remains the leading cause of death in the developed world. Advanced age is the single strongest risk factor for coronary artery disease (CAD) and independent predictor for poor outcomes following an acute coronary syndrome (ACS). ACS refers to a spectrum of conditions compatible with acute myocardial ischemia and/or infarction due to various degrees of reduction in coronary blood flow as a result of plaque rupture/erosion and thrombosis formation or supply and demand mismatch. Unstable angina and non-ST segment elevation myocardial infarction are often continuous and clinically indistinguishable, collectively referred as non-ST elevation ACS (NSTE-ACS). An abrupt total occlusion of a coronary artery causing transmural myocardial ischemia/necrosis and displaying ST segment elevation or new left bundle branch block on a12-lead ECG leads to the diagnosis of ST segment elevation myocardial infarction (STEMI). NSTE-ACS and STEMI require acute cardiac care. Professional societies have established guidelines for high quality contemporary care for ACS patients, i.e., American Heart Association/American College of Cardiology guidelines for STEMI and NSTE-ACS, European Society of Cardiology guidelines for STEMI and NSTE-ACS, and the United Kingdom National Institute for Health and Care Excellence guidelines for STEMI and NSTE-ACS.[1]–[6] Implementation of evidence-based therapies has significantly decreased mortality and morbidities of ACS.[3],[7],[8] However, these advancements in ACS management have not equally improved outcomes for older adults. Vulnerable older patients continue to be at high risk of poor outcomes, are less likely to receive evidence based care, and have high mortality rates regardless of treatments given.[9],[10] These disparities and challenges in caring for ACS in older adults are well recognized.[11]–[13] This review summarizes the increasing burden and persistent unfavorable outcome of ACS in older adults, and discusses the clinical presentation, diagnosis and strategies for medical and invasive therapy

The Chemical Genetic Interactions of Statin Drugs with Their Target Genes in Saccharomyces cerevisiae

Statins, competitive inhibitors of the rate limiting cholesterol/ergosterol enzymes HMG-CoA reductase (HMG1 and HMG2), are the most widely prescribed human therapeutic drugs. They are effective in lowering cholesterol levels in atherosclerosis and related syndromes. However, statins exhibit a range of pleiotropic side effects whose mechanisms are poorly understood. This study investigates statin pleiotropy by analysis of genetic interaction networks in yeast, Saccharomyces cerevisiae, which shows high homology to mammalian pathways affected by statins. Synthetic genetic array (SGA) analysis allows elucidation of functional genetic networks of genes of interest ("query genes") by measurement of genetic epistasis in double mutants of the query gene with the genome - wide deletion mutant array of ~4800 non-essential strains. Chemicalgenetic profiling is similar where a SMP may effectively replace the query gene in genome wide epistatic analysis. The genetic interaction networks resulting from use of HMG1 and HMG2 as query genes for SGA analysis were compared to the chemical-genetic profiles of atorvastatin, cerivastatin and lovastatin. The genes ARV1, BTS1, OPI3 displaying phenotypic enhancements (i.e. their deletion caused major growth inhibition) with statins became essential in the presence of all the statins. Two mitochondrial genes, COX17 and MMM1, showed phenotypic suppressions (i.e. their deletion allowed better growth) in common to all three statin drugs. An attractive hypothesis is that major pleiotropic effects of statins could be due to variation in function or expression of these enhancing or suppressing genes. Other processes compensating statin use were also elucidated. For example, when HMG1 and its epistatically interacting genes are shut down by deletion coupled with inhibition of HMG2 with statin, there is strong evidence that the cell attempts to maintain membrane/lipid homeostasis via anterograde and retrograde transport mechanisms, including the mobilisation of lipid storage droplets. To aid refinement of genetic analysis in this and future studies, a more direct phenotypic assay was developed for quantifying ergosterol. Such an assay may be used as a phenotype to map the effect of up - and downstream - genes, or network genes affecting ergosterol levels. This assay was used to quantify ergosterol in a drug - resistant mutant developed by others aiding confirmation of the drug target

Constructive Gelfand duality for C*-algebras

We present a constructive proof of Gelfand duality for C*-algebras by reducing the problem to Gelfand duality for real C*-algebras.Comment: 6page

Stable ischemic heart disease in the older adults

Ischemic heart disease is caused by atherosclerotic and/or thrombotic obstruction of coronary arteries. Clinical spectrum of ischemic heart disease expands from asymptomatic atherosclerosis of coronary arteries to acute coronary syndromes (ACS) including unstable angina, acute myocardial infarction (non-ST elevation myocardial infarction and ST elevation myocardial infarction). Stable ischemic heart disease (SIHD) refers to patients with known or suspected SIHD who have no recent or acute changes in their symptomatic status, suggesting no active thrombotic process is underway. These patients include those with (1) recent-onset or stable angina or ischemic equivalent symptoms, such as dyspnea or arm pain with exertion; (2) post-ACS stabilized after revascularization or medical therapy; and (3) asymptomatic SIHD diagnosed by abnormal stress tests or imaging studies. This review summarizes clinical features and management of SIHD in the older adult. ACS in older adults is not considered in this review

Regional modelling of permafrost thicknesses over the past 130 ka: implications for permafrost development in Great Britain

The greatest thicknesses of permafrost in Great Britain most likely occurred during the last glacial–interglacial cycle, as this is when some of the coldest conditions occurred during the last 1 000 000 years. The regional development of permafrost across Great Britain during the last glacial–interglacial cycle was modelled from a ground surface temperature history based on mean annual temperatures and the presence of glacier ice. To quantify the growth and decay of permafrost, modelling was undertaken at six locations across Great Britain that represent upland glaciated, lowland glaciated, upland unglaciated and lowland unglaciated conditions. Maximum predicted permafrost depths derived in this academic study range between several tens of metres to over 100 m depending upon various factors including elevation, glacier ice cover, geothermal heat flux and air temperature. In general, the greatest maximum permafrost thicknesses occur at upland glaciated locations, with minimum thickness at lowland sites. Current direct geological evidence for permafrost is from surface or shallow processes, mainly associated with the active layer. Further research is recommended to identify the imprint of freeze/thaw conditions in permanently frozen porous rocks from beneath the active layer

Hyperhomocysteinemia is Associated with Aortic Atheroma Progression in Stroke/TIA Patients

Significance: Aortic arch (AA) atheroma and AA atheroma progression are independent risk factors for recurrent vascular events in stroke/transient ischemic attack (TIA) patients. Total homocysteine level (tHcy) is an independent risk marker for atherosclerosis including that found in AA. The purpose of this study was to prospectively test the association between AA atheroma progression and tHcy. Methods: This is a cohort study of 307 consecutive hospitalized stroke/TIA patients undergoing transesophageal echocardiogram (TEE) as a part of their clinical workup. Measurable AA atheroma was detected in 167 patients of whom 125 consented to a protocol-mandated follow-up TEE at 12 months. Patients had evaluation for vascular risk factors, dietary factors (folate, B12 and pyridoxine), and methylene tetrahydrofolate reductase (MTHFR) polymorphism. One hundred eighteen stroke/TIA patients had tHcy, acceptable paired AA images, and detailed plaque measurements. An increase by ≥1 grade of AA atheroma was defined as progression. Results: Of the 118 patients, 33 (28%) showed progression and 17 (14%) showed regression of their index arch lesion at 1 year. tHcy (≥14.0 μmol/l) was significantly associated with progression on both univariate (RR = 3.4, 95% CI 2.0–5.8) and multivariate analyses (adjusted RR = 3.6, 95% CI 2.2–4.6). The changes in AA plaque thickness (r2 = 0.11; p < 0.001) and AA plaque area (r2 = 0.08; p = 0.002) correlated with tHcy. tHcy was associated with change in plaque thickness over 12 months, independent of age, dietary factors, renal function and MTHFR polymorphism (Standardized β-coefficient 0.335, p = 0.02). Conclusions: Our results validate the association and a linear correlation between tHcy and progression of AA atheroma

Yield and Production Costs for Three Potential Dedicated Energy Crops in Mississippi and Oklahoma Environments

The objective of this paper is to determine production costs of switchgrass, eastern gammagrass, and giant miscanthus using Mississippi and Oklahoma data. Production costs were computed using a standard enterprise budgeting approach by species and method of harvest. Results indicate cost difference across species and method of harvest.Yield and Cost, biomass species, Crop Production/Industries, Resource /Energy Economics and Policy,