2014 Vol. 28, No. 1
Atrial fibrillation is the most common arrhythmia affecting patients today. Disease prevalence is increasing at an alarming rate worldwide, and is associated with often catastrophic and costly consequences, including heart failure, syncope, dementia, and stroke. Therapies including anticoagulants, anti-arrhythmic medications, devices, and non-pharmacologic procedures in the last 30 years have improved patients' functionality with the disease. Nonetheless, it remains imperative that further research into AF epidemiology, genetics, detection, and treatments continues to push forward rapidly as the worldwide population ages dramatically over the next 20 years.
Hypertension is a multifactorial condition which makes the development of treatment approaches difficult. The vast majority of patients are treated with lifestyle measures either alone or in combination with antihypertensive drugs, and this approach is largely successful in controlling blood pressure. However, for a subgroup of patients, control of blood pressure remains resistant to this approach and therefore the development of new strategies is im?perative. The sympathetic nervous system has been known to be implicated in hypertension for many decades, and evidence from studies in the past has revealed the benefit of reducing sympathetic nerve activity in the control of blood pressure albeit with severe side effects. Recent technological advances have allowed for specific targeting of the renal sympathetic nerves by catheter ablation. The Symplicity HTN-1 and HTN-2 trials have provided strong evidence for renal denervation giving rise to considerable blood pressure reductions in treatment-resistant hyper?tensives and, due to the high incidence of hypertension worldwide, this carries the promise of further reducing the global burden of hypertension and its attendant complications. Here we review the evidence for renal denervation in the management of hypertension.
Extracellular matrix (ECM) within the vascular network provides both a structural and regulatory role. The ECM is a dynamic composite of multiple proteins that form structures connecting cells within the network. Blood vessels are distended by blood pressure and, therefore, require ECM components with elasticity yet with enough tensile strength to resist rupture. The ECM is involved in conducting mechanical signals to cells. Most importantly, ECM regulates cellular function through chemical signaling by controlling activation and bioavail-ability of the growth factors. Cells respond to ECM by remodeling their microenvironment which becomes dys-regulated in vascular diseases such hypertension, restenosis and atherosclerosis. This review examines the cellu-lar and ECM components of vessels, with specific emphasis on the regulation of collagen type I and implications in vascular disease.
Vascular smooth muscle cell (VSMC) differentiation and proliferation are two important physiological proc?esses during vascular development. The phenotypic alteration from differentiated to proliferative VSMC contrib?utes to the development of several major cardiovascular diseases including atherosclerosis, hypertension, resteno?sis after angioplasty or bypass, diabetic vascular complications, and transplantation arteriopathy. Since the VSMC phenotype in these pathological conditions resembles that of developing VSMC during embryonic development, understanding of the molecular mechanisms that control VSMC differentiation will provide fundamental insights into the pathological processes of these cardiovascular diseases. Although VSMC differentiation is usually ac?companied by an irreversible cell cycle exit, VSMC proliferation and differentiation occur concurrently during embryonic development. The molecular mechanisms simultaneously regulating these two processes, however, remain largely unknown. Our recent study demonstrates that cell division cycle 7, a key regulator of cell cycle, promotes both VSMC differentiation and proliferation through different mechanisms during the initial phase of VSMC differentiation. Conversely, Krüppel-like factor 4 appears to be a repressor for both VSMC differentia?tion and proliferation. This review attempts to highlight the novel role of cell division cycle 7 in TGF-β-induced VSMC differentiation and proliferation. The role of Krüppel-like factor 4 in suppressing these two processes will also be discussed.
Atherosclerosis is a progressive human pathology that encompasses several stages of development. Endothelial dysfunction represents an early sign of lesion within the vasculature. A number of risk factors for atherosclero?sis, including hyperlipidemia, diabetes, and hypertension, target the vascular endothelium by re-programming its transcriptome. These profound alterations taking place on the chromatin rely on the interplay between sequence specific transcription factors and the epigenetic machinery. The epigenetic machinery, in turn, tailor individual transcription events key to atherogenesis to intrinsic and extrinsic insults dictating the development of atheroscle?rotic lesions. This review summarizes our current understanding of the involvement of the epigenetic machinery in endothelial injury during atherogenesis.
Plasma lipid abnormalities are implicated in the pathogenic process of type 2 diabetes. The IDE-KIF11-HHEX gene cluster on chromosome 10q23.33 has been identified as a susceptibility locus for type 2 diabetes. We hy?pothesized that genetic variants at 10q23.33 may be associated with plasma lipid concentrations. Seven tagging single nucleotide polymorphisms (SNPs: rs7923837, rs2488075, rs947591, rs11187146, rs5015480, rs4646957 and rs1111875) at 10q23.33 were genotyped in 3,281 subjects from a Han Chinese population, using the Taq?Man OpenArray and Sequenom MassARRAY platforms. Multiple linear regression analyses showed that SNP rs7923837 in the 3'-flanking region of HHEX was significantly associated with triglyceride levels (P = 0.019, 0.031 mmol/L average decrease per minor G allele) and that rs2488075 and rs947591 in the downstream region of HHEX were significantly associated with total cholesterol levels (P = 0.041, 0.058 mmol/L average decrease per minor C allele and P = 0.018, 0.063 mmol/L average decrease per minor A allele, respectively). However, the other four SNPs (rs11187146, rs5015480, rs4646957 and rs1111875) were not significantly associated with any plasma lipid concentrations in this Chinese population. Our data suggest that genetic variants in the IDE-KIF11- HHEX gene cluster at 10q23.33 may partially explain the variation of plasma lipid levels in the Han Chinese pop?ulation. Further studies are required to confirm these findings in other populations.
Pediatric restrictive cardiomyopathy is rare and most commonly idiopathic in origin. Here, we applied a candi-date gene approach and identified a missense mutation in the cardiac troponin I gene in a 12-year-old Chinese girl with restrictive cardiomyopathy. This study indicates that mutation in sarcomere protein genes may play an im-portant role in idiopathic pediatric restrictive cardiomyopathy.
We sought to compare the safety and accuracy of a new free-hand pedicle screw placement technique to that of the conventional technique. One hundred fifty-three consecutive adult patients with simple fracture in the tho-racic or/and lumbar spine were alternately assigned to either the new free-hand or the conventional group. In the new free-hand technique group, preoperative computerized tomography (CT) images were used to calculate the targeted medial-lateral angle of each pedicle trajectory and the pedicle screw was inserted perpendicular to the corresponding supraspinal ligament. In the conventional technique group, the medial-lateral and cranial-caudal angle of each pedicle trajectory was determined by intraoperatively under fluoroscopic guidance. The accuracy rate of pedicle screw placement, the time of intraoperative fluoroscopy, the operating time and the amount of blood loss during operation were respectively compared. All screws were analyzed by using intraoperative ra-diographs, intraoperative triggered electromyography (EMG) monitoring data, postoperative CT data and clinical outcomes. The accuracy rate of pedicle screw placement in the new free-hand technique group and the conven-tional technique group was 96.3% and 94.2% (P < 0.05), respectively. The intraoperative fluoroscopy time of the new technique group was less than that of the conventional technique group (5.37 seconds vs. 8.79 seconds, P < 0.05). However, there was no statistical difference in the operating time and the amount of blood loss during op-eration (P > 0.05). Pedicle screw placement with the free-hand technique which keeps the screw perpendicular to the supraspinal ligament is an accurate, reliable and safe technique to treat simple fracture in the thoracic or lum-bar spine.