Genetic and environmental influences on factors associated with cardiovascular disease and the metabolic syndrome

The relative influence of genetics and the environment on factors associated with cardiovascular disease (CVD) and metabolic syndrome (MetS) remains unclear. We performed model-fitting analyses to quantify genetic, common environmental, and unique environmental variance components of factors associated with CVD and MetS [waist circumference, blood pressure, fasting plasma glucose and insulin, homeostatic model assessment of insulin resistance (HOMA-IR), and fasting plasma lipids] in adult male and female monozygotic twins reared apart or together. We also investigated whether MetS components share common influences. Plasma cholesterol and triglyceride concentrations were highly heritable (56–77%, statistically significant). Waist circumference, plasma glucose and insulin, HOMA-IR, and blood pressure were moderately heritable (43–57%, statistically significant). Unique environmental factors contributed to the variance of all variables (20–38%, perforce statistically significant). Common environmental factors contributed 23, 30, and 42% (statistically significant) of the variance of waist circumference, systolic blood pressure, and plasma glucose, respectively. Two shared factors influenced MetS components; one influenced all components except HDL cholesterol, another influenced only lipid (triglyceride and HDL cholesterol) concentrations. These results suggest that genetic variance has a dominant influence on total variance of factors associated with CVD and MetS and support the proposal of one or more underlying pathologies of MetS.     

Monocyte Derived Microvesicles Deliver a Cell Death Message via Encapsulated Caspase-1

Apoptosis depends upon the activation of intracellular caspases which are classically induced by either an intrinsic (mitochondrial based) or extrinsic (cytokine) pathway. However, in the process of explaining how endotoxin activated monocytes are able to induce apoptosis of vascular smooth muscle cells when co-cultured, we uncovered a transcellular apoptosis inducing pathway that utilizes caspase-1 containing microvesicles. Endotoxin stimulated monocytes induce the cell death of VSMCs but this activity is found in 100,000 g pellets of cell free supernatants of these monocytes. This activity is not a direct effect of endotoxin, and is inhibited by the caspase-1 inhibitor YVADcmk but not by inhibitors of Fas-L, IL-1β and IL-18. Importantly, the apoptosis inducing activity co-purifies with 100 nm sized microvesicles as determined by TEM of the pellets. These microvesicles contain caspase-1 and caspase-1 encapsulation is required since disruption of microvesicular integrity destroys the apoptotic activity but not the caspase-1 enzymatic activity. Thus, monocytes are capable of delivering a cell death message which depends upon the release of microvesicles containing functional caspase-1. This transcellular apoptosis induction pathway describes a novel pathway for inflammation induced programmed cell death.     

Detection and expression of the phosphonate transporter gene phnD in marine and freshwater picocyanobacteria

We describe a PCR-based assay designed to detect expression of the phosphonate assimilation gene phnD from picocyanobacteria. The phnD gene encodes the phosphonate binding protein of the ABC-type phosphonate transporter, present in many of the picocyanobacterial genome sequences. Detection of phnD expression can indicate a capacity of picoplankton to utilize phosphonates, a refractory form of phosphorus that can represent 25% of the high-molecular-weight dissolved organic phosphorus pool in marine systems. Primer sets were designed to specifically amplify phnD sequences from marine and freshwater Synechococcus spp., Prochlorococcus spp. and environmental samples from the ocean and Laurentian Great Lakes. Quantitative RT-PCR from cultured marine Synechococcus sp. strain WH8102 and freshwater Synechococcus sp. ARC-21 demonstrated induction of phnD expression in P-deficient media, suggesting that phn genes are regulated coordinately with genes under phoRB control. Last, RT-PCR of environmental RNA samples from the Sargasso Sea and Pacific Ocean detected phnD expression from the endemic picocyanobacterial population. Synechococcus spp. phnD expression yielded a depth-dependent pattern following gradients of P bioavailability. By contrast, the Prochlorococcus spp. primers revealed that in all samples tested, phnD expression was constitutive. The method described herein will allow future studies aimed at understanding the utilization of naturally occurring phoshonates in the ocean as well as monitoring the acquisition of synthetic phosphonate herbicides (e.g. glyphosate) by picocyanobacteria in freshwaters.     

Differentiated human adipose‐derived stem cells exhibit hepatogenic capability in vitro and in vivo

The availability of suitable human livers for transplantation falls short of the number of potential patients. In addition, the availability of primary human hepatocytes for cell‐therapy and drug development applications is significantly limited; less than 700 livers per year are available for such studies. However, the majority of these organs cannot be utilized due to pathological infections (e.g., HepB, HepC, or HIV) or excessive levels of steatosis. Thus, the number of cells needed for cell therapy applications far exceeds the number of cells available from donated livers. The ability to implant progenitor cell populations that can form liver tissue in situ, or can be differentiated in vitro would be a major advance in current cell‐based therapies. In addition, and importantly for this application, the ability to utilize a non‐hepatic progenitor cell to mimic hepatocytes in vitro would enable the scale‐up production of cells for bioartifical liver assist devices, cell‐therapy and drug discovery applications. We demonstrate the feasibility of inducing adipose‐derived stromal (ASC) cells to express several features of human hepatocytes such as glycogen storage and expression of liver specific genes. Importantly, we also show that undifferentiated ASCs and ASC‐derived hepatic cells engraft robustly into the liver in a mouse model of toxic injury. These data indicate a significant potential for the use of undifferentiated ASCs and ASC‐derived hepatic cells as novel and valuable products for cell therapy. J. Cell. Physiol. 225: 429–436, 2010. © 2010 Wiley‐Liss, Inc.     

Unique gating properties of C. elegans ClC anion channel splice variants are determined by altered CBS domain conformation and the R-helix linker

All eukaryotic and some prokaryotic ClC anion transport proteins have extensive cytoplasmic C-termini containing two cystathionine-β-synthase (CBS) domains. CBS domain secondary structure is highly conserved and consists of two α-helices and three β-strands arranged as β1-α1-β2-β3-α2. ClC CBS domain mutations cause muscle and bone disease and alter ClC gating. However, the precise functional roles of CBS domains and the structural bases by which they regulate ClC function are poorly understood. CLH-3a and CLH-3b are C. elegans ClC anion channel splice variants with strikingly different biophysical properties. Splice variation occurs at cytoplasmic N- and C-termini and includes several amino acids that form α2 of the second CBS domain (CBS2). We demonstrate that interchanging α2 between CLH-3a and CLH-3b interchanges their gating properties. The “R-helix” of ClC proteins forms part of the ion-conducting pore and selectivity filter and is connected to the cytoplasmic C-terminus via a short stretch of cytoplasmic amino acids termed the “R-helix linker”. C-terminus conformation changes could cause R-helix structural rearrangements via this linker. X-ray structures of three ClC protein cytoplasmic C-termini suggest that α2 of CBS2 and the R-helix linker could be closely apposed and may therefore interact. We found that mutating apposing amino acids in α2 and the R-helix linker of CLH-3b was sufficient to give rise to CLH-3a-LIKE gating. We postulate that the R-helix linker interacts with CBS2 α2, and that this putative interaction provides a pathway by which cytoplasmic C-terminus conformational changes induce conformational changes in membrane domains that in turn modulate ClC function.Key words: ClC channel, chloride channel, homology model     

Surgical correction of unsuccessful derotational humeral osteotomy in obstetric brachial plexus palsy: Evidence of the significance of scapular deformity in the pathophysiology of the medial rotation contracture

Background

The current method of treatment for persistent internal rotation due to the medial rotation contracture in patients with obstetric brachial plexus injury is humeral derotational osteotomy. While this procedure places the arm in a more functional position, it does not attend to the abnormal glenohumeral joint. Poor positioning of the humeral head secondary to elevation and rotation of the scapula and elongated acromion impingement causes functional limitations which are not addressed by derotation of the humerus. Progressive dislocation, caused by the abnormal positioning and shape of the scapula and clavicle, needs to be treated more directly.

Methods

Four patients with Scapular Hypoplasia, Elevation And Rotation (SHEAR) deformity who had undergone unsuccessful humeral osteotomies to treat internal rotation underwent acromion and clavicular osteotomy, ostectomy of the superomedial border of the scapula and posterior capsulorrhaphy in order to relieve the torsion developed in the acromio-clavicular triangle by persistent asymmetric muscle action and medial rotation contracture.

Results

Clinical examination shows significant improvement in the functional movement possible for these four children as assessed by the modified Mallet scoring, definitely improving on what was achieved by humeral osteotomy.

Conclusion

These results reveal the importance of recognizing the presence of scapular hypoplasia, elevation and rotation deformity before deciding on a treatment plan. The Triangle Tilt procedure aims to relieve the forces acting on the shoulder joint and improve the situation of the humeral head in the glenoid. Improvement in glenohumeral positioning should allow for better functional movements of the shoulder, which was seen in all four patients. These dramatic improvements were only possible once the glenohumeral deformity was directly addressed surgically.     

Endoplasmic reticulum stress-induced apoptosis and auto-immunity in diabetes

Increasing evidence suggests that stress signaling pathways emanating from the endoplasmic reticulum (ER) are important to the pathogenesis of both type 1 and type 2 diabetes. Recent observations indicate that ER stress signaling participates in maintaining the ER homeostasis of pancreatic beta-cells. Either a high level of ER stress or defective ER stress signaling in beta-cells may cause an imbalance in ER homeostasis and lead to beta-cell apoptosis and autoimmune response. In addition, it has been suggested that ER stress attributes to insulin resistance in patients with type 2 diabetes. It is necessary to study the relationship between ER stress and diabetes in order to develop new therapeutic approaches to diabetes based on drugs that block the ER stress-mediated cell-death pathway and insulin resistance.