calcium handling

Glucocorticoid-induced osteoporosis is the most common secondary cause of osteoporosis and the resulting fractures cause significant morbidity. Following initiation of oral glucocorticoids, rapid bone loss occurs, and fracture risk increases within a few months in a dose-dependent manner. These adverse effects are due to inhibition of bone formation accompanied by an early but transient increase in bone resorption. Multiple mechanisms underlie these changes in bone remodeling; direct effects include upregulation of PPARγR2, increased expression of sclerostin and increased RANKL/OPG ratio, whilst hypogonadism, altered renal and intestinal calcium handling, and reduced production of insulin-like growth factor 1 also contribute...

Several classes of ligands for Protease-Activated Receptors (PARs) have shown impressive anti-inflammatory and cytoprotective activities, including PAR2 antagonists and the PAR1-targeting parmodulins. In order to support medicinal chemistry studies with hundreds of compounds and to perform detailed mode-of-action studies, it became important to develop a reliable PAR assay that is operational with endothelial cells, which mediate the cytoprotective effects of interest. We report a detailed protocol for an intracellular calcium mobilization assay with adherent endothelial cells in multiwell plates that was used to study a number of known and new PAR1 and PAR2 ligands, including an alkynylated version of the PAR1 antagonist RWJ-58259 that is suitable for the preparation of tagged or conjugate compounds...

The success of in vitro fertilization is strongly influenced by genetic background, handling of sperm and oocytes, and culture conditions. This protocol promotes enhanced rates of fertilization by using preincubation medium for sperm containing methyl-β-cyclodextrin (MBCD) and fertilization medium with high calcium and reduced glutathione (GSH).

Physical activity plays an important role in preventing muscle atrophy and chronic diseases in adults and in the elderly. Calcium (Ca2+ ) cycling and activation of specific molecular pathways are essential in contraction-induced muscle adaptation. This study attains human muscle sections and total homogenates prepared from biopsies obtained before (control) and after 9 weeks of training by electrical stimulation (ES) on a group of volunteers. The aim of the study was to investigate about the molecular mechanisms that support functional muscle improvement by ES...

The fine regulation of intracellular calcium is fundamental for all eukaryotic cells. In neurons, Ca2+ oscillations govern the synaptic development, the release of neurotransmitters and the expression of several genes. Alterations of Ca2+ homeostasis were found to play a pivotal role in neurodegenerative progression. The maintenance of proper Ca2+ signaling in neurons demands the continuous activity of Ca2+ pumps and exchangers to guarantee physiological cytosolic concentration of the cation. The plasma membrane Ca2+ ATPases (PMCA pumps) play a key role in the regulation of Ca2+ handling in selected sub-plasma membrane microdomains...

Background -Mutations in RBM20 cause a clinically aggressive form of dilated cardiomyopathy (DCM), with an increased risk of malignant ventricular arrhythmias. RBM20 is a splicing factor that targets multiple pivotal cardiac genes, such as Titin (TTN) and Calcium/calmodulin-dependent kinase II delta (CAMK2D). Aberrant TTN splicing is thought to be the main determinant of RBM20-induced DCM, but is not likely to explain the increased risk of arrhythmias. Here, we investigated the extent at which RBM20 mutation carriers have an increased risk of arrhythmias and explore the underlying molecular mechanism...

A 61-year-old woman presented with chronic anterior pain and stiffness in the distal left thigh. Examination revealed swelling and tenderness immediately proximal to the patella. Radiographs showed opacities in the distal anterior thigh whilst MRI identified enlargement of the distal quadriceps tendon with splayed fibres separated by solid conglomerates. Dystrophic calcification of the quadriceps tendon was diagnosed. Blood tests revealed no systemic abnormalities in calcium handling. Arthroscopy of the left knee identified calcific deposits in the supra-patella pouch with surrounding synovitis...

Diabetes mellitus is a growing health care problem, resulting in significant cardiovascular morbidity and mortality. Diabetes also increases the risk for heart failure (HF) and decreased cardiac myocyte function, which are linked to changes in cardiac mitochondrial energy metabolism. The free mitochondrial calcium level ([Ca2+]m) is fundamental in activating the mitochondrial respiratory chain complexes and ATP production and is also known to regulate pyruvate dehydrogenase complex (PDC) activity. The mitochondrial calcium uniporter (MCU) complex (MCUC) plays a major role in mediating mitochondrial Ca2+ import, and its expression and function therefore have a marked impact on cardiac myocyte metabolism and function...

Chronic heart failure (CHF) is a major contributor to cardiovascular disease and is the leading cause of hospitalization for those over the age of 65, which is estimated to account for close to seventy billion dollars in healthcare costs by 2030 in the US alone. The successful therapies for preventing and reversing CHF progression are urgently required. One strategy under active investigation is to restore dysregulated myocardial calcium (Ca2+ ), a hallmark of CHF. It is well established that intracellular Ca2+ concentrations are tightly regulated to control efficient myocardial systolic contraction and diastolic relaxation...

Aging is associated with a decline in cardiac function due to a decreased myocardial reserve. This adverse cardiac remodeling comprises of a variety of changes, including a reduction in mitochondrial function and a decline in the expression of the peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), a central regulator of mitochondrial biogenesis and metabolic adaptation in the myocardium. To study the etiological involvement of PGC-1α in cardiac aging, we used mouse models mimicking the modest down- and upregulation of this coactivator in the old and the exercised heart, respectively...

Cardiac tissues generated from human induced pluripotent stem cells (iPSCs) can serve as platforms for patient-specific studies of physiology and disease1-6 . However, the predictive power of these models is presently limited by the immature state of the cells1, 2, 5, 6 . Here we show that this fundamental limitation can be overcome if cardiac tissues are formed from early-stage iPSC-derived cardiomyocytes soon after the initiation of spontaneous contractions and are subjected to physical conditioning with increasing intensity over time...

Expression of the glutamine transporter SNAT3 increases in kidney during metabolic acidosis, suggesting a role during ammoniagenesis. Microarray analysis of Nrf2 knock-out (KO) mouse kidney identified Snat3 as the most significantly down-regulated transcript compared to wild-type (WT). We hypothesized that in the absence of NRF2 the kidney would be unable to induce SNAT3 under conditions of metabolic acidosis and therefore reduce the availability of glutamine for ammoniagenesis. Metabolic acidosis was induced for 7 days in WT and Nrf2 KO mice...

The overwhelming majority of patients with chronic kidney disease (CKD) die prematurely before reaching end-stage renal disease, mainly due to cardiovascular causes, of which heart failure is the predominant clinical presentation. We hypothesized that CKD-induced increases of plasma FGF23 impair cardiac diastolic and systolic function. To test this, mice were subjected to 5/6 nephrectomy (5/6Nx) or were injected with FGF23 for seven consecutive days. Six weeks after surgery, plasma FGF23 was higher in 5/6Nx mice compared to sham mice (720 ± 31 vs...

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) grown in engineered heart tissue (EHT) can be used for drug screening, disease modeling, and heart repair. However, the immaturity of hiPSC-CMs currently limits their use. Because mechanical loading increases during development and facilitates cardiac maturation, we hypothesized that afterload would promote maturation of EHTs. To test this we developed a system in which EHTs are suspended between a rigid post and a flexible one, whose resistance to contraction can be modulated by applying braces of varying length...

Background -Advances in congestive heart failure (CHF) management depend on biomarkers for monitoring disease progression and therapeutic response. During systole, intracellular Ca2+ is released from the sarcoplasmic reticulum (SR) into the cytoplasm through type 2 ryanodine receptor/Ca2+ release channels (RyR2). In CHF, chronically elevated circulating catecholamine levels cause pathologic remodeling of RyR2 resulting in diastolic SR Ca2+ leak, and decreased myocardial contractility. Similarly, skeletal muscle contraction requires SR Ca2+ release through type-1 ryanodine receptors (RyR1), and chronically elevated catecholamine levels in CHF cause RyR1 mediated SR Ca2+ leak, contributing to myopathy and weakness...

Interleukin-1 (IL-1) is the prototypical pro-inflammatory cytokine. IL-1 was implicated as a cardiodepressant factor in septic shock, and subsequent pre-clinical and clinical research has defined important roles for IL-1 in atherosclerosis, acute myocardial infarction (AMI), and heart failure (HF). IL-1 promotes the formation of the atherosclerotic plaque and facilitates its progression and complication. In a large phase III clinical trial of stable patients with prior AMI, blocking IL-1 activity using a monoclonal antibody prevented recurrent atherothrombotic cardiovascular events...

Calcium phosphate-loaded carboxymethyl cellulose non-woven sheets (CMC/CaP sheet) were fabricated and their potential to induce in vitro osteoblast differentiation and in vivo bone regeneration were investigated. The CMC/CaP sheets were prepared by alternately soaking protonated-CMC non-woven sheets in CaCl2 and Na2 HPO4 aqueous solutions. Because of its slow water uptake rate, the protonated-CMC was successfully loaded with a mixed phase of brushite and hydroxyapatite. In vitro, the CMC/CaP sheet induced osteoblast differentiation of human mesenchymal stromal cells (hMSCs), as shown by calcification and the upregulation of osteoblast marker genes...

The aim of the present work was to develop a medication allowing for the combined delivery of platelet lysate (PL) and an anti-infective model drug, vancomycin hydrochloride (VCM), to chronic skin ulcers. A simple method was set up for the preparation of hyaluronic acid (HA) core-shell particles, loaded with PL and coated with calcium alginate, embedded in a VCM containing alginate matrix. Two different CaCl2 concentrations were investigated to allow for HA/PL core-shell particle formation. The resulting dressings were characterized for mechanical and hydration properties and tested in vitro (on fibroblasts) and ex-vivo (on skin biopsies) for biological activity...

Thirty three surface sediments were collected for the present study to assess the elemental concentration and its associated ecological risk in the reef associated surface sediments, Appa Island, Gulf of Mannar Biosphere Reserve, South east coast of India. The distribution of calcium carbonate in the reef sediments is controlled by coral debris and shell fragments whereas the Organic matter (OM) content are chiefly derived from mangroves and sea grasses. The circulation of trace elements and Fe, Mn are controlled by the fluvial process and re-suspended sediments...

Coronary artery calcification (CAC) is a widespread condition in chronic kidney disease (CKD). Diet may play an important role in CAC, but this role is not clear. This study evaluated the association between macro-and micronutrient intakes and CAC in non-dialysis CKD patients. We analyzed the baseline data from 454 participants of the PROGREDIR study. Dietary intake was evaluated by a food frequency questionnaire. CAC was measured by computed tomography. After exclusion of participants with a coronary stent, 373 people remained for the analyses...