Showing papers by "Mark E. Cooper published in 2009"

A Trial of Darbepoetin Alfa in Type 2 Diabetes and Chronic Kidney Disease

Abstract: Background Anemia is associated with an increased risk of cardiovascular and renal events among patients with type 2 diabetes and chronic kidney disease. Although darbepoetin alfa can effectively increase hemoglobin levels, its effect on clinical outcomes in these patients has not been adequately tested. Methods In this study involving 4038 patients with diabetes, chronic kidney disease, and anemia, we randomly assigned 2012 patients to darbepoetin alfa to achieve a hemoglobin level of approximately 13 g per deciliter and 2026 patients to placebo, with rescue darbepoetin alfa when the hemoglobin level was less than 9.0 g per deciliter. The primary end points were the composite outcomes of death or a cardiovascular event (nonfatal myocardial infarction, congestive heart failure, stroke, or hospitalization for myocardial ischemia) and of death or end-stage renal disease. Results Death or a cardiovascular event occurred in 632 patients assigned to darbepoetin alfa and 602 patients assigned to placebo (hazard...

Albuminuria and Kidney Function Independently Predict Cardiovascular and Renal Outcomes in Diabetes

Abstract: There are limited data regarding whether albuminuria and reduced estimated GFR (eGFR) are separate and independent risk factors for cardiovascular and renal events among individuals with type 2 diabetes. The Action in Diabetes and Vascular disease: preterAx and diamicroN-MR Controlled Evaluation (ADVANCE) study examined the effects of routine BP lowering on adverse outcomes in type 2 diabetes. We investigated the effects of urinary albumin-to-creatinine ratio (UACR) and eGFR on the risk for cardiovascular and renal events in 10,640 patients with available data. During an average 4.3-yr follow-up, 938 (8.8%) patients experienced a cardiovascular event and 107 (1.0%) experienced a renal event. The multivariable-adjusted hazard ratio for cardiovascular events was 2.48 (95% confidence interval 1.74 to 3.52) for every 10-fold increase in baseline UACR and 2.20 (95% confidence interval 1.09 to 4.43) for every halving of baseline eGFR, after adjustment for regression dilution. There was no evidence of interaction between the effects of higher UACR and lower eGFR. Patients with both UACR >300 mg/g and eGFR <60 ml/min per 1.73 m(2) at baseline had a 3.2-fold higher risk for cardiovascular events and a 22.2-fold higher risk for renal events, compared with patients with neither of these risk factors. In conclusion, high albuminuria and low eGFR are independent risk factors for cardiovascular and renal events among patients with type 2 diabetes.

Can Changes in Canopy and/or Root System Architecture Explain Historical Maize Yield Trends in the U.S. Corn Belt?

Abstract: Continuous increase in the yield of maize (Zea mays L.) in the U.S. Corn Belt has involved an interaction with plant density. A number of contributing traits and mechanisms have been suggested. In this study we used a modeling approach to examine whether changes in canopy and/or root system architecture might explain the observed trends. A maize crop model was generalized so that changes in canopy and root system architecture could be examined. A layered, diurnal canopy photosynthesis model was introduced to predict consequences of change in canopy architecture. A two-dimensional root exploration model was introduced to predict consequences of change in root system architecture. Field experiments were conducted to derive model parameters for the base hybrid (Pioneer 3394). Simulation studies for various canopy and root system architectures were undertaken for a range of sites, soils, and densities. Simulated responses to density compared well with those found in field experiments. The analysis indicated that (i) change in root system architecture and water capture had a direct effect on biomass accumulation and historical yield trends; and (ii) change in canopy architecture had little direct effect but likely had important indirect effects via leaf area retention and partitioning of carbohydrate to the ear. The study provided plausible explanations and identified testable hypotheses for future research and crop improvement effort.

RAGE-Induced Cytosolic ROS Promote Mitochondrial Superoxide Generation in Diabetes

Abstract: Damaged mitochondria generate an excess of superoxide, which may mediate tissue injury in diabetes. We hypothesized that in diabetic nephropathy, advanced glycation end-products (AGEs) lead to increases in cytosolic reactive oxygen species (ROS), which facilitate the production of mitochondrial superoxide. In normoglycemic conditions, exposure of primary renal cells to AGEs, transient overexpression of the receptor for AGEs (RAGE) with an adenoviral vector, and infusion of AGEs to healthy rodents each induced renal cytosolic oxidative stress, which led to mitochondrial permeability transition and deficiency of mitochondrial complex I. Because of a lack of glucose-derived NADH, which is the substrate for complex I, these changes did not lead to excess production of mitochondrial superoxide; however, when we performed these experiments in hyperglycemic conditions in vitro or in diabetic rats, we observed significant generation of mitochondrial superoxide at the level of complex I, fueled by a sustained supply of NADH. Pharmacologic inhibition of AGE-RAGE–induced mitochondrial permeability transition in vitro abrogated production of mitochondrial superoxide; we observed a similar effect in vivo after inhibiting cytosolic ROS production with apocynin or lowering AGEs with alagebrium. Furthermore, RAGE deficiency prevented diabetes-induced increases in renal mitochondrial superoxide and renal cortical apoptosis in mice. Taken together, these studies suggest that AGE-RAGE–induced cytosolic ROS production facilitates mitochondrial superoxide production in hyperglycemic environments, providing further evidence of a role for the advanced glycation pathway in the development and progression of diabetic nephropathy.

Therapies for hyperglycaemia-induced diabetic complications: from animal models to clinical trials

Abstract: Long-term diabetes increases the likelihood of developing secondary damage to numerous systems, and these complications represent a substantial cause of morbidity and mortality. Establishing the causes of diabetes remains the key step towards eradicating the disease, but the prevention and amelioration of diabetic complications is equally important for the millions of individuals who already have the disease or are likely to develop it before prophylaxis or a cure become routinely available. In this Review, we focus on four common complications of diabetes, discuss the range of pathologies that are precipitated by hyperglycaemia and highlight emerging targets for therapeutic intervention.

Lowering Blood Pressure Reduces Renal Events in Type 2 Diabetes

Abstract: BP is an important determinant of kidney disease among patients with diabetes. The recommended thresholds to initiate treatment to lower BP are 130/80 and 125/75 mmHg for people with diabetes and nephropathy, respectively. We sought to determine the effects of lowering BP below these currently recommended thresholds on renal outcomes among 11,140 patients who had type 2 diabetes and participated in the Action in Diabetes and Vascular disease: preterAx and diamicroN-MR Controlled Evaluation (ADVANCE) study. Patients were randomly assigned to fixed combination perindopril-indapamide or placebo, regardless of their BP at entry. During a mean follow-up of 4.3 yr, active treatment reduced the risk for renal events by 21% (P < 0.0001), which was driven by reduced risks for developing microalbuminuria and macroalbuminuria (both P < 0.003). Effects of active treatment were consistent across subgroups defined by baseline systolic or diastolic BP. Lower systolic BP levels during follow-up, even to <110 mmHg, was associated with progressively lower rates of renal events. In conclusion, BP-lowering treatment with perindopril-indapamide administered routinely to individuals with type 2 diabetes provides important renoprotection, even among those with initial BP <120/70 mmHg. We could not identify a BP threshold below which renal benefit is lost.

Risks of cardiovascular events and effects of routine blood pressure lowering among patients with type 2 diabetes and atrial fibrillation: results of the ADVANCE study.

Abstract: AIMS: The aim of this study was to investigate serious clinical outcomes associated with atrial fibrillation (AF) and the effects of routine blood pressure lowering on such outcomes in the presence or absence of AF, among individuals with type 2 diabetes. METHODS AND RESULTS: About 11 140 patients with type 2 diabetes (7.6% of whom had AF at baseline) were randomized to a fixed combination of perindopril and indapamide or placebo in the Action in Diabetes and Vascular Disease: preterAx and diamicroN-MR Controlled Evaluation (ADVANCE) study. We compared total mortality and cardiovascular disease outcomes and effects of randomized treatment for 4.3 years on such outcomes between patients with and without AF at baseline. After multiple adjustments, AF was associated with a 61% (95% confidence interval 31-96, P < 0.0001) greater risk of all-cause mortality and comparable higher risks of cardiovascular death, stroke, and heart failure (all P < 0.001). Routine treatment with a fixed combination of perindopril and indapamide produced similar relative, but greater absolute, risk reductions for all-cause and cardiovascular mortalities in patients with AF, compared with those without AF. The number of patients needed to be treated with perindopril-indapamide for 5 years to prevent one cardiovascular death was 42 for patients with AF and 120 for patients without AF at baseline. CONCLUSION: Atrial fibrillation is relatively common in type 2 diabetes and is associated with substantially increased risks of death and cardiovascular events in patients with type 2 diabetes. This arrhythmia identifies individuals who are likely to obtain greater absolute benefits from blood pressure-lowering treatment. Atrial fibrillation in diabetic patients should be regarded as a marker of particularly adverse outcome and prompt aggressive management of all risk factors.

Reconstituted high-density lipoprotein attenuates platelet function in individuals with type 2 diabetes mellitus by promoting cholesterol efflux.

Abstract: Background— Individuals with diabetes mellitus have an increased risk of cardiovascular disease and exhibit platelet hyperreactivity, increasing their resistance to antithrombotic therapies such as aspirin and clopidogrel. Reconstituted high-density lipoprotein (rHDL) has short-term beneficial effects on atherosclerotic plaques, but whether it can effectively reduce the reactivity of diabetic platelets is not known. Methods and Results— Individuals with type 2 diabetes mellitus were infused with placebo or rHDL (CSL-111; 20 mg · kg−1 · h−1) for 4 hours, resulting in an ≈1.4-fold increase in plasma HDL cholesterol levels. rHDL infusion was associated with a >50% reduction in the ex vivo platelet aggregation response to multiple agonists, an effect that persisted in washed platelets. In vitro studies in platelets from healthy individuals revealed that the inhibitory effects of rHDL on platelet function were time and dose dependent and resulted in a widespread attenuation of platelet function and a 50% reduc...

Modelling Crop Improvement in a G×E×M Framework via Gene–Trait–Phenotype Relationships

Abstract: This chapter introduces fundamental concepts of modeling natural systems using a G×E×M framework and discusses the prospects for an integrated approach for improving crop performance that tackles the G×E×M interactions holistically. It outlines general principles of modeling biophysical systems, including a description of fundamental components of crop models. It describes G×E×M systems and introduces gene-to-phenotype (GP) models and concepts of adaptation landscapes as applied to plant breeding. The chapter discusses the application of the framework by studying genetic improvement of maize in the US Corn Belt. It reviews and summarizes theoretical developments toward a framework that integrates quantitative genetics, breeding simulation, and modeling of physiological traits and dynamic GP relations. Such a framework is intended to enable breeders and agronomists to project trajectories in the G×E×M space into the future and gain insights on the consequences of manipulating genomes to the creation of improved crops for target management and environments.

Label-Free Biosensors: Techniques and Applications

Abstract: Label-free biosensors are devices that use biological or chemical receptors to detect analytes (molecules) in a sample. They give detailed information on the selectivity, affinity, and, in many cases, also the binding kinetics and thermodynamics of an interaction. Although they can be powerful tools in the hands of a skilled user, there is often a lack of knowledge of the best methods for using label-free assays to screen for biologically active molecules and accurately and precisely characterize molecular recognition events. This book reviews both established and newer label-free techniques giving both the expert user and the general reader interested in the technologies and applications behind label-free an insight into the field from expert opinion leaders and practitioners of the technologies. Most importantly, chapters contain worked examples from leaders in the field that take the reader through the basics of experimental design, setup, assay development, and data analysis.

Site-Specific Antiatherogenic Effect of the Antioxidant Ebselen in the Diabetic Apolipoprotein E–Deficient Mouse

Abstract: Objective— Recently we showed that lack of the antioxidant enzyme glutathione peroxidase-1 (GPx1) accelerates atherosclerosis and upregulates proatherogenic pathways in diabetic apoE/GPx1-deficient double-knockout mice, thereby establishing GPx1 as an important therapeutic target. In vivo studies now investigate ebselen, a seleno-organic GPx1-mimetic, for its potential to reduce diabetes-associated atherosclerosis. Methods and Results— Lesions were significantly increased in diabetic apoE −/− aortas ( P P P P P −/− mice. These reductions were accompanied by significantly lower nitrotyrosine and Nox2 levels, reduced proatherogenic cellularity (macrophages and SMCs), and reduced expression of the proatherogenic mediator RAGE. Within the aortic sinus, ebselen reduced nitrotyrosine, Nox2, and VEGF levels but had no effect on RAGE. Studies in HAECs show that ebselen abrogates H 2 O 2 -induced increases in P-IKK, P-JNK, TNF-α, and Nox2. Conclusions— Ebselen reduces atherosclerotic lesions in most regions of diabetic apoE −/− aorta, except within the aortic sinus, suggesting its effectiveness as a potential antiatherogenic therapy in diabetic-macrovascular disease. Ebselen may elicit its effect via modulation of transcription factors such as NF-κB and AP-1.

Early Maastrichtian carbon cycle perturbation and cooling event: Implications from the South Atlantic Ocean

Abstract: Published stable isotope records in marine carbonate are characterized by a positive ?18O excursion associated with a negative ?13C shift during the early Maastrichtian. However, the cause and even the precise timing of these excursions remain uncertain. We have generated high-resolution foraminiferal stable isotope and grey scale records for the latest Campanian to early Maastrichtian (~73-68 Ma) at two Ocean Drilling Program sites, 525 (Walvis Ridge) and 690 (Weddell Sea). We demonstrate that the negative ?13C excursion is decoupled from the ?18O increase with a lag of about 600 kyr. Our ?13C records (both planktic and benthic) show an amplitude for the negative excursion of 0.7 ‰ that falls between about 72.1 and 70.7 Ma. Our planktic ?18O records indicate an overall increase of 1.2 ‰ from 73 to 68 Ma at Site 690, whereas at Site 525 they record a slightly smaller increase (~1 ‰) that peaks around 70.1 Ma with decreasing values thereafter. Our benthic ?18O data indicate an increase of ~1.5 ‰ at Site 525 and ~0.7 ‰ at Site 690 between about 71.4 and 69.9 Ma. Benthic ?18O values show different baseline values at the two sites before and after the excursion but the larger increase at Site 525 means that the values attained at the peak of the excursion are similar at the two sites. We interpret this observation in terms of water mass changes. The excursion is interpreted to reflect a cooling of bottom waters in response to the strengthening contribution of intermediate- to deep-water production in the high southern latitudes rather than increased ice volume. The associated carbon-cycle perturbations that we observe are interpreted to reflect a weakening of surface-water stratification and increased productivity, as supported by our grey value data.

Blood Pressure Variables and Cardiovascular Risk: New Findings From ADVANCE

Abstract: The relative importance of various blood pressure indices on cardiovascular risk in people with type 2 diabetes mellitus has not been established. This study compares the strengths of the associations between different baseline blood pressure variables (systolic blood pressure [SBP], diastolic blood pressure [DBP], pulse pressure [PP], and mean arterial pressure) and the 4.3-year risk of major cardiovascular events in the Action in Diabetes and Vascular Disease: Preterax and Diamicron-Modified Release Controlled Evaluation Study. Mean (SD) age for the 11 140 participants was 65.8 years (6.4 years). During follow-up, 1000 major cardiovascular events, 559 major coronary events, and 468 cardiovascular deaths were recorded. After adjustment for age, sex, and treatment allocation, the hazard ratios (95% CIs) associated with 1 increment in SD for the risk of major cardiovascular events were 1.17 (1.10 to 1.24) for SBP; 1.20 (1.13 to 1.28) for PP; 1.12 (1.05 to 1.19) for mean arterial pressure; and 1.04 (0.98 to 1.11) for DBP. The areas under the receiver operating characteristic curve were slightly higher for SBP and PP compared with mean arterial pressure and DBP for major cardiovascular and coronary events. Using achieved instead of baseline blood pressure values marginally improved the effect estimates for SBP, DBP, and mean arterial pressure, with no significant differences in the areas under the receiver operating characteristic curve between models with SBP and those with PP. In conclusion, SBP and PP are the 2 best and DBP is the least effective determinant of the risk of major cardiovascular outcomes in the relatively old patients with type 2 diabetes mellitus participating in the Action in Diabetes and Vascular Disease: Preterax and Diamicron-Modified Release Controlled Evaluation Study. However, SBP may be the simplest and most useful predictor across a wider range of age groups and populations.

Ocular Delivery of Compacted DNA-Nanoparticles Does Not Elicit Toxicity in the Mouse Retina

Abstract: Subretinal delivery of polyethylene glycol-substituted lysine peptide (CK30PEG)-compacted DNA nanoparticles results in efficient gene expression in retinal cells. This work evaluates the ocular safety of compacted DNA nanoparticles. CK30PEG-compacted nanoparticles containing an EGFP expression plasmid were subretinally injected in adult mice (1 µl at 0.3, 1.0 and 3.0 µg/µl). Retinas were examined for signs of inflammation at 1, 2, 4 and 7 days post-injection. Neither infiltration of polymorphonuclear neutrophils or lymphocytes was detected in retinas. In addition, elevation of macrophage marker F4/80 or myeloid marker myeloperoxidase was not detected in the injected eyes. The chemokine KC mRNA increased 3–4 fold in eyes injected with either nanoparticles or saline at 1 day post-injection, but returned to control levels at 2 days post-injection. No elevation of KC protein was observed in these mice. The monocyte chemotactic protein-1, increased 3–4 fold at 1 day post-injection for both nanoparticle and saline injected eyes, but also returned to control levels at 2 days. No elevations of tumor necrosis factor alpha mRNA or protein were detected. These investigations show no signs of local inflammatory responses associated with subretinal injection of compacted DNA nanoparticles, indicating that the retina may be a suitable target for clinical nanoparticle-based interventions.

A Study of Renal Outcomes in African American Living Kidney Donors

Abstract: BACKGROUND Little is known about the long-term outcomes of African American living kidney donors (AALKDs). We undertook this study to describe renal outcomes of AALKDs several years after donation. METHODS We invited 107 AALKDs to come for follow-up health evaluation. RESULTS Thirty-nine subjects (36.4%) completed evaluation at a mean of 7.1+/-1.6 (range, 3.9-10.2) years postdonation. The mean estimated glomerular filtration rate using the abbreviated Modification of Diet in Renal Disease equation [eGFR(MDRD)] at follow-up was 72.1+/-16.3 (range, 42-106) mL/min/1.73 m2, and 18% of subjects had an eGFR(MDRD) of 30 to 59. The mean absolute and relative decrease in eGFR(MDRD) from the time of donation to follow-up was 30.5+/-16.4 mL/min/1.73 m2 and 28.8%, respectively. Subjects whose body mass index was more than or equal to 35 kg/m2 (n=8) were found to have a greater decrement in e(MDRD) than those with body mass index less than 35 kg/m2 (40.1+/-7.3 and 28.3+/-17.1 mL/min/1.73 m2, respectively; P=0.009). Sixteen (41%) were hypertensive at follow-up, as defined as treatment with antihypertensive medications (n=8) or average blood pressure of more than or equal to 140 systolic or 90 mm Hg diastolic (n=10, of whom two were on antihypertensive medications). One subject had macroalbuminuria (>300 microg/mg creatinine), and six (15.4%) had microalbuminuria (30-300 microg/mg creatinine). CONCLUSIONS AALKDs experience a substantial incidence of hypertension and a modest drop in eGFR(MDRD) postdonation, and obesity may increase the magnitude of renal decline. Further study is urgently needed to determine the long-term risks of AALKDs.

Metabolic memory: implications for diabetic vascular complications.

Abstract: Cooper ME. Metabolic memory: implications for diabetic vascular complications. Pediatric Diabetes 2009.

c-Jun NH2-Terminal Kinase Activity in Subcutaneous Adipose Tissue but Not Nuclear Factor-κB Activity in Peripheral Blood Mononuclear Cells Is an Independent Determinant of Insulin Resistance in Healthy Individuals

Abstract: OBJECTIVE Chronic low-grade activation of the immune system (CLAIS) predicts type 2 diabetes via a decrease in insulin sensitivity. Our study investigated potential relationships between nuclear factor-κB (NF-κB) and c-Jun NH 2 -terminal kinase (JNK) pathways—two pathways proposed as the link between CLAIS and insulin resistance. RESEARCH DESIGN AND METHODS Adiposity (dual-energy X-ray absorptiometry), waist-to-hip ratio (WHR), and insulin sensitivity ( M , hyperinsulinemic-euglycemic clamp) were measured in 22 healthy nondiabetic volunteers (aged 29 ± 11 years, body fat 28 ± 11%). NF-κB activity (DNA-binding assay) and JNK1/2 activity (phosphorylated JNK) were assessed in biopsies of the vastus lateralis muscle and subcutaneous adipose tissue and in peripheral blood mononuclear cell (PBMC) lysates. RESULTS NF-κB activities in PBMCs and muscle were positively associated with WHR after adjustment for age, sex, and percent body fat (both P M after adjustment for age, sex, percent body fat, and WHR ( P = 0.02) and explained 16% of the variance of M . There were no significant relationships between NF-κB activity and M in muscle or adipose tissue (both NS). Adipose-derived JNK1/2 activity was not associated with obesity (all P > 0.1), although it was inversely related to M ( r = −0.54, P P = 0.02). CONCLUSIONS JNK1/2 activity in adipose tissue but not NF-κB activity in PBMCs is an independent determinant of insulin resistance in healthy individuals.

Community Diversity at Ban Lum Khao, Thailand: Isotopic Evidence from the Skeletons

Abstract: In this study we compare isotopes in human teeth with burial artifacts at a Bronze Age site in Thailand, to identify immigrants and delimit discrete social groups. One of the aims of the Origins of Angkor Archaeological Project is to assess seminal aspects of the social, cultural, and technological development in the Mun River valley of Northeast Thailand. Ranging from the Neolithic through the Bronze Age to the Iron Age, multiple archaeological sites and cemeteries of this valley document the development of human society from simple agrarian origins to a complex, hierarchical, and specialized society, culminating in the Angkor civilization. One of these sites, Ban Lum Khao, settled during the late Neolithic, was used as a cemetery in the Bronze Age, after 1050 b.c. (T. Higham 2004). The cemetery, of which 110 graves were uncovered, appears to show all the indications of

Possible association between genetic polymorphisms in transforming growth factor β receptors, serum transforming growth factor β1 concentration and abdominal aortic aneurysm

Abstract: Background: Previous studies have suggested a role for transforming growth factor (TGF) β and its receptor in thoracic aortic aneurysm, but their role in abdominal aortic aneurysm (AAA) is unknown This study examined the possible association between TGF-β receptor 1 and 2 (TGFBR-1 and -2) single nucleotide polymorphisms (SNPs) and serum TGF-β1 with AAA Methods: Serum concentrations of TGF-β1 and 58 SNPs for TGFBR-1 and -2 were examined in 1003 and 1711 men respectively from the Health In Men Study Validation of SNPs was examined in a second referral cohort of 1043 subjects from New Zealand, of whom 654 had an AAA Results: Serum TGF-β1 was not associated with AAA Only one SNP in TGFBR-2 was weakly associated with AAA; TGFBR2 g42917C > T, SNP ID rs1078985CC; odds ratio 0·64 (95 per cent confidence interval (ci) 0·45 to 0·93); P = 0·020 uncorrected; but this association did not hold after adjusting for multiple testing and was not validated in the New Zealand cohort: odds ratio 0·98 (95 per cent ci 0·50 to 1·94); P = 0·960 Conclusion: These findings suggest there is no important role of genetic polymorphisms in the main receptors for TGF-β and circulating TGF-β1 in AAA in older individuals

Quantitative Detection of Staphylococcal Enterotoxin B by Resonant Acoustic Profiling

Abstract: A rapid and sensitive detection of staphylococcal enterotoxin B (SEB) was developed using a novel acoustic sensing technique: Resonant Acoustic Profiling (RAP), which utilizes high-frequency piezoelectric quartz resonators for monitoring biomolecular interactions. An automated four-channel instrument consisting of acoustic sensors covalently conjugated with anti-SEB antibodies was used. As the samples flowed across control and active sensors simultaneously, binding was measured as a change in the resonant frequency. The lower limit of detection (LLOD) for the label free direct format was 25 ng/mL. Detection sensitivity was increased by adding mass sequentially to the captured SEB on the sensor in the form of sandwich antibodies and biotin−avidin-based gold nanoparticles. The LLOD for the mass enhanced formats were 5 and 0.5 ng/mL of SEB, respectively. The lowest sensitivity corresponds to 1.3 fM in a 75 μL sample. The total assay time including the enhancement steps was less than 10 min. SEB was detected ...

Label-Free Biosensors

Abstract: Label-free biosensors use biological or chemical receptors to detect analytes (molecules) in a sample. They give detailed information on the binding selectivity, affinity, and, in many cases, the stoichiometry, kinetics, and thermodynamics of an interaction. Although they can be powerful tools in the hands of a skilled user, there is often a lack of knowledge regarding the best way to utilize label-free assays to screen for biologically active molecules and to accurately and precisely characterize molecular recognition events. This book reviews both established and newer label-free techniques. It is intended to give both the expert user and the general reader insight into the field from expert opinion leaders and practitioners of these techniques. Chapters also contain worked examples that are written to guide the reader through the basics of experimental design, setup, assay development, and data analysis.

REE and Sr isotope characteristics of carbonate within the Cu–Co mineralized sedimentary sequence of the Nchanga Mine, Zambian Copperbelt

Abstract: Carbonate, largely in the form of dolomite, is found throughout the host rocks and ores of the Nchanga mine of the Zambian Copperbelt. Dolomite samples from the hanging wall of the mineralization show low concentrations of rare-earth elements (REE) and roof-shaped, upward convex, shale-normalized REE patterns, with positive Eu*SN anomalies (1.54 and 1.39) and marginally negative Ce anomalies (Ce*SN 0.98,0.93). In contrast, dolomite samples associated with copper and cobalt mineralization show a significant rotation of the REE profile, with HREE enrichment, and La/LuSN ratios <1 (0.06–0.42). These samples also tend to show variable but predominantly negative Eu*SN and positive cerium anomalies and an upwardly concave MREE distribution (Gd-Er). Malachite samples from the Lower Orebody show roof-tile-normalized REE patterns with negative europium anomalies (Eu*SN 0.65–0.80) and negative cerium anomalies (Ce*SN 0.86–0.9). The carbonate 87Sr/86Sr signature correlates with the associated REE values. The uppermost dolomite samples show Neoproterozoic seawater-like 87Sr/86Sr ratios ranging from 0.7111 to 0.7116, whereas carbonate from Cu–Co mineralized samples show relatively low concentrations of strontium and more radiogenic 87Sr/86Sr, ranging between 0.7136–0.7469. The malachite samples show low concentrations of strontium, but give a highly radiogenic 87Sr/86Sr of 0.7735, the most radiogenic 87Sr/86Sr ratio. These new data suggest that the origin and timing of carbonate precipitation at Nchanga is reflected in the REE and Sr isotope chemistry. The upper dolomite samples show a modified, but essentially seawater-like signature, whereas the rotation of the REE profile, the MREE enrichment, the development of a negative Eu*SN anomaly and more radiogenic 87Sr/86Sr suggests the dolomite in the Cu–Co mineralized samples precipitated from basinal brines which had undergone significant fluid–rock interaction. Petrographic, REE, and 87Sr/86Sr data for malachite are consistent with the original sulfide Lower Orebody being subject to a later oxidizing event.

Signal transduction profiling using label-free biosensors

Abstract: Knowledge of the way in which ligands modulate cellular responses via membrane-associated receptors is of central importance to drug discovery and elucidation of signal transduction pathways. Biophysical label-free methods can be used to characterize ligand and drug candidate interactions with neurotransmitters, cytokine receptors, tyrosine kinase receptors, ligand- and voltage-gated ion channels, G protein-coupled receptors (GPCRs), and antibody receptors. Ligand or drug candidate screening typically involves selecting ligands or subsets of a compound library for analysis, transfecting a cell line overexpressing the target receptor, then monitoring one or two downstream reporters of receptor activation such as Ca(2+), cAMP, inositol phosphate, etc. Inevitably, this process leads to a data set predicated by these selections. In contrast, label-free screening techniques allow a holistic, pathway-independent screening strategy to provide a functional or phenotypic readout of receptor activation. Detection techniques that measure changes in cell conductance, viscoelastic properties, refractive index, and other optical parameters that are modulated as a consequence of receptor activation are reviewed.

Long-term consequences of kidney donation.

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Eplerenone does not attenuate diabetes-associated atherosclerosis.

Abstract: Background It has been suggested that aldosterone, with its known pro-inflammatory and profibrotic actions, may play a key role in the development and progression of atherosclerosis Method In this study, the ability of aldosterone antagonism to reduce atherosclerosis in experimental diabetes was assessed Diabetes was induced in ApoE knockout mice with streptozotocin, and the mice were treated with the specific aldosterone antagonist, eplerenone, in their feed over 20 weeks (approximately 200 mg/kg per day) Result En face analysis revealed that eplerenone treatment was unable to attenuate atherosclerosis as assessed by percentage lesion area quantitation in the aortae of these mice compared with untreated diabetic mice (diabetic, 107 +/- 11; diabetic + eplerenone, 88 +/- 12%) In contrast, we observed a significant, more than 50% decrease in percentage of plaque area in the nondiabetic control groups Despite this lack of effect in the diabetic mice, eplerenone treatment was associated with reduced cytosolic superoxide production However, aortic transcript levels of key molecules implicated in diabetes-associated atherogenesis, such as monocyte chemoattractant protein-1 and vascular cell adhesion molecule-1, were not significantly attenuated by eplerenone Conclusion These findings suggest that eplerenone treatment may not be as antiatherosclerotic in the diabetic context