2015 Vol. 29, No. 1
Myocardin (MYOCD) is a potent transcriptional coactivator that functions primarily in cardiac muscle and smooth muscle through direct contacts with serum response factor (SRF) over cis elements known as CArG boxes found near a number of genes encoding for contractile, ion channel, cytoskeletal, and calcium handling proteins. Since its discovery more than 10 years ago, new insights have been obtained regarding the diverse isoforms of MYOCD expressed in cells as well as the regulation of MYOCD expression and activity through transcriptional, post-transcriptional, and post-translational processes. Curiously, there are a number of functions associated with MYOCD that appear to be independent of contractile gene expression and the CArG-SRF nucleoprotein complex. Further, perturbations in MYOCD gene expression are associated with an increasing number of diseases including heart failure, cancer, acute vessel disease, and diabetes. This review summarizes the various biological and pathological processes associated with MYOCD and offers perspectives to several challenges and future directions for further study of this formidable transcriptional coactivator.
2015, 29(1): 20-34. doi: 10.7555/JBR.29.20140147
Electrical storm, defined as 3 or more separate episodes of ventricular tachycardia or ventricular fibrillation within 24 hours, carries significant morbidity and mortality. These unstable ventricular arrhythmias have been described with a variety of conditions including ischemic heart disease, structural heart disease, and genetic conditions. While implantable cardioverter defibrillator implantation and ablation may be indicated and required, antiarrhythmic medication remains an important adjunctive therapy for these persons.
Ventricular tachycardia storm (VTS) is defined as a life-threatening syndrome of three or more separate episodes of ventricular tachycardia (VT) leading to implantable cardioverter defibrillator (ICD) therapy within 24 hours. Patients with VTS have poor outcomes and require immediate medical attention. ICD shocks have been shown to be associated with increased mortality in several studies. Optimal programming in minimization of ICD shocks may decrease mortality. Large controlled trials showed that long detection time and high heart rate detection threshold reduced ICD shock burden without an increase in syncope or death. As a fundamental therapy of ICD, antitachycardia pacing (ATP) can terminate most slow VT with a low risk of acceleration. For fast VT, burst pacing is more effective and less likely to result in acceleration than ramp pacing. One algorithm of optimal programming management during a VTS is presented in the review.
Ventricular fibrillation (VF) is a malignant arrhythmia, usually initiated by a ventricular premature contraction (VPC) during the vulnerable period of cardiac repolarization. Ablation therapy for VF has been described and increasingly reported. Targets for VF triggers are VPCs preceded by Purkinje potentials or from the right ventricular outflow tract (RVOT) in structurally normal hearts, and VPC triggers preceded by Purkinje potentials in ischemic cardiomyopathy. During the session, mapping should be focused on the earliest activation and determining the earliest potential is the key to a successful ablation. However, suppression of VF can be achieved by not only the elimination of triggering VPCs, but also by substrate modification of possible reentry circuits in the Purkinje network, or between the PA and RVOT. The most important issue before the ablation session is the recording of the 12-lead ECG of the triggering event, which can prove invaluable in regionalizing the origin of the triggering VPC for more detailed mapping. In cases where the VPC is not spontaneous or inducible, ablation may be performed by pace mapping. Further studies are needed to evaluate the precise mechanisms of this arrhythmia.
The electrical storm (ES) is defined as a state of electrical instability with three or more sustained ventricular arrhythmias (VAs) occurring within twenty-four hours, which needs intravenous antiarrhythmic medications and frequent defibrillation. Recently, radiofrequency catheter ablation evolved as a sole therapy to terminate ES in patients with ICD, and the survival has been reported to be improved with successful ablation during follow-up. In this review, we briefly summarize substrate mapping and substrate ablation strategy in patients with ES, and discuss the reason of recurrence after ablation.
In the hyperadrenergic state of VT storm where shocks are psychologically and physiologically traumatizing, suppression of sympathetic outflow from the organ level of the heart up to higher braincenters plays a significant role in reducing the propensity for VT recurrence. The autonomic nervous system continuously receives input from the heart (afferent signaling), integrates them, and sends efferent signals to modify or maintain cardiac function and arrhythmogenesis. Spinal anesthesia with thoracic epidural infusion of bupivicaine and surgical removal of the sympathetic chain including the stellate ganglion has been shown to decrease recurrences of VT. Excess sympathetic outflow with catecholamine release can be modified with catheter-based renal denervation. The insights provided from animal experiments and in patients that are refractory to conventional therapy have significantly improved our working understanding of the heart as an end organ in the autonomic nervous system.
Gastroenteritis is considered as one of the leading causes of illness and death in children under 5 years age, especially in developing countries. It is one of the major public health problems among childhood in Gaza strip, Palestine. This study was conducted to determine the prevalence of enteric pathogen-associated community gastroenteritis among kindergarten children in Gaza. A total of 150 stool samples were collected and investigated for parasitic, viral and bacterial pathogens at Al Azhar microbiology laboratories by using standard microbiological and serological procedures. Out of the 150 study samples, the overall percentage of positive stool samples with a known enteric pathogen was 60.6%. The prevalence of different enteric pathogens causing community gastroenteritis among symptomatic cases (88.5%) was significantly higher than the prevalence in asymptomatic carriage (11.1%). The most prevalent isolated enteric pathogens were Entamoeba histolytica (28.0%) and Giardia lamblia (26.7%). Rotavirus was found in 3.1% of symptomatic cases but not detected in asymptomatic carriage. However, adenovirus type 40 and 41 were not detected in any of the study samples. The bacterial enteric pathogens Shigella and Enterohemorrhagic Escherichia coli O157:H7 (EHEC) have comparable occurrence as rotavirus (3.1%), meanwhile, Salmonella was not isolated. Mixed infection with more than 1 pathogen was found (11.4%) only among symptomatic cases. Children aged 3-year-old showed the highest prevalence of community gastroenteritis. This study demonstrates a high prevalence of parasitic enteropathogens and a relatively low prevalence of bacterial and viral enteropathogens among kindergarten children living in Gaza city, moreover, children aged 3 years old showed the highest prevalence of isolated enteropathogens.
In the current study, we sought to establish a novel rat model of portal vein arterialization (PVA) and evaluate its impact on liver regeneration after extended partial hepatectomy (PH). A total of 105 Sprague-Dawley rats were randomly assigned to three groups: 68% hepatectomy (the PH group), portal arterialization after 68% hepatectomy (the PVA group), and right nephrectomy only (the control group). Liver regeneration rate (LRR), 5-bromo-2-deoxyuridine (BrdU) labeling index, and liver functions were assessed on postoperative day 2, 7, 14 and 28. The 28-day survival rates were compared among the three groups. The 28-day survival rates were similar in all groups (P 5 0.331), and the anastomotic patency was 100%. The LRR in the PVA group was significantly higher than that of the PH group within postoperative 14 days (P , 0.05). The PVA and PH group had increased serum alanine aminotransferase levels (232 ? 61 U/L and 212 ? 53 U/L, respectively) compared with the control group (101 ? 13 U/L) on postoperative day 2, whereas from postoperative day 7 to day 28 there were no differences among the three groups. Serum albumin values were higher after the PVA procedure within postoperative day 14, which gradually became comparable on postoperative day 28 among the three groups. The peaks of BrdU labeling index appeared on postoperative day 2 in all rats, and the PVA procedure was associated with increased BrdU labeling index from postoperative day 7 to 28. The 28-day survival of the PVA rats was comparable. Our findings demonstrate that the PVA procedure utilizing portal vein trunk-renal artery microvascular reconstruction promotes remnant liver regeneration and confers beneficial effects on maintaining and even optimizing liver function after extended partial hepatectomy in rats.
This study aimed to introduce a novel mini-open pedicle screw fixation technique via Wiltse approach, and compared it with the traditional posterior open method. A total of 72 cases of single-segment thoracolumbar fractures without neurologic injury underwent pedicle screw fixation via two different approaches. Among them, 37 patients were treated using posterior open surgery, and 35 patients received mini-open operation via Wiltse approach. Crew placement accuracy rate, operative time, blood loss, postoperative drainage, postoperative hospitalization time, radiation exposure time, postoperative improvement in R value, Cobb9 s angle and visual analog scale (VAS) scores of the two methods were compared. There were no significant differences in the accuracy rate of pedicle screw placement, radiation exposure and postoperative R value and Cobb9 s angle improvement between the two groups. However, the mini-open method had obvious advantages over the conventional open method in operative time, blood loss, postoperative drainage, postoperative hospitalization time, and postoperative improvement in VAS. The mini-open pedicle screw technique could be applied in treatment of single-segment thoracolumbar fracture without neurologic injury and had advantages of less tissue trauma, short operative and rehabilitative time on the premise of guaranteed accuracy rate and no increased radiation exposure.
We report an extremely rare case of an unruptured non-communicating rudimentary horn full-term pregnancy. A woman who had a uterine malformation was misdiagnosed as uterus didelphys and gave birth to a live, healthy fetus. The correct diagnosis was not made until cesarean section at 37 4/7 weeks. The case suggests that women who are pregnant in a rudimentary horn could obtain a full-term delivery and give birth to a live and healthy baby.