Effects of the cardiomyopathy-causing E244D mutation of troponin T on the structures of cardiac thin filaments studied by small-angle X-ray scattering

Small-angle X-ray scattering experiments were carried out to investigate the structural changes of cardiac thin filaments induced by the cardiomyopathy-causing E244D mutation in troponin T (TnT). We examined native thin filaments (NTF) from a bovine heart, reconstituted thin filaments containing human cardiac wild-type Tn (WTF), and filaments containing the E244D mutant of Tn (DTF), in the absence and presence of Ca²⁺. Analysis by model calculation showed that upon Ca²⁺-activation, tropomyosin (Tm) and Tn in the WTF and NTF moved together in a direction to expose myosin-binding sites on actin. On the other hand, Tm and Tn of the DTF moved in the opposite directions to each other upon Ca²⁺-activation. These movements caused Tm to expose more myosin-binding sites on actin than the WTF, suggesting that the affinity of myosin for actin is higher for the DTF. Thus, the mutation-induced structural changes in thin filaments would increase the number of myosin molecules bound to actin compared with the WTF, resulting in the force enhancement observed for the E244D mutation.     

Type III-A CRISPR-Cas Csm Complexes: Assembly,Periodic RNA Cleavage,DNase Activity Regulation,and Autoimmunity

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Contributions of the C-terminal domain to poly(A)-specific ribonuclease (PARN) stability and self-association

Poly(A)-specific ribonuclease (PARN) catalyzes the degradation of mRNA poly(A) tail to regulate translation efficiency and mRNA decay in higher eukaryotic cells. The full-length PARN is a multi-domain protein containing the catalytic nuclease domain, the R3H domain, the RRM domain and the C-terminal intrinsically unstructured domain (CTD). The roles of the three well-structured RNA-binding domains have been extensively studied, while little is known about CTD. In this research, the impact of CTD on PARN stability and aggregatory potency was studied by comparing the thermal inactivation and denaturation behaviors of full-length PARN with two N-terminal fragments lacking CTD. Our results showed that K⁺ induced additional regular secondary structures and enhanced PARN stability against heat-induced inactivation, unfolding and aggregation. CTD prevented PARN from thermal inactivation but promoted thermal aggregation to initiate at a temperature much lower than that required for inactivation and unfolding. Blue-shift of Trp fluorescence during thermal transitions suggested that heat treatment induced rearrangements of domain organizations. CTD amplified the stabilizing effect of K⁺, implying the roles of CTD was mainly achieved by electrostatic interactions. These results suggested that CTD might dynamically interact with the main body of the molecule and release of CTD promoted self-association via electrostatic interactions.     

A comparison of clinical outcomes following atrial fibrillation ablation for heart failure patients with preserved or reduced left ventricular function: A systematic review and meta-analysis

BackgroundThis review aims to determine if patients who undergo atrial fibrillation (AF) ablation with heart failure with preserved ejection fraction (HFpEF) do better, or worse or the same compared to patients with heart failure with reduced ejection fraction (HFrEF).MethodsA search of MEDLINE and EMBASE was performed using the search terms: “atrial fibrillation”, “ablation” and terms related to HFpEF and HFrEF in order to identify studies that evaluated one or more of i) AF recurrence, ii) periprocedural complications and iii) adverse outcomes at follow up for patients with HFpEF and HFrEF who underwent AF ablation. Data was extracted from included studies and statistically pooled to evaluate adverse events and AF recurrence.Results5 studies were included in this review and the sample size of the studies ranged from 91 to 521 patients with heart failure. There was no significant difference in the pooled rate for no AF or symptom recurrence after AF ablation comparing patients with HFpEF vs HFrEF (RR 1.07 95%CI 0.86–1.33, p = 0.15). The most common complications were access site complications/haematoma/bleeding which occurred in similar proportion in each group; HFpEF (3.1%) and HFrEF (3.1%). In terms of repeat ablations, two studies were pooled to yield a rate of 78/455 (17.1%) for HFpEF vs 24/279 (8.6%) for HFrEF (p = 0.001.ConclusionsHeart failure patients with preserved or reduced ejection fraction have similar risk of AF or symptom recurrence after AF ablation but two studies suggest that patients with HFpEF are more likely to have repeat ablations.     

New insights on ChlD1 function in Photosystem II from site-directed mutants of D1/T179 in Thermosynechococcus elongatus

The monomeric chlorophyll, Chl_D1, which is located between the P_D1P_D2 chlorophyll pair and the pheophytin, Pheo_D1, is the longest wavelength chlorophyll in the heart of Photosystem II and is thought to be the primary electron donor. Its central Mg²⁺ is liganded to a water molecule that is H-bonded to D1/T179. Here, two site-directed mutants, D1/T179H and D1/T179V, were made in the thermophilic cyanobacterium, Thermosynechococcus elongatus, and characterized by a range of biophysical techniques. The Mn₄CaO₅ cluster in the water-splitting site is fully active in both mutants. Changes in thermoluminescence indicate that i) radiative recombination occurs via the repopulation of *Chl_D1 itself; ii) non-radiative charge recombination reactions appeared to be faster in the T179H-PSII; and iii) the properties of P_D1P_D2 were unaffected by this mutation, and consequently iv) the immediate precursor state of the radiative excited state is the Chl_D1⁺Pheo_D1^? radical pair. Chlorophyll bleaching due to high intensity illumination correlated with the amount of ¹O₂ generated. Comparison of the bleaching spectra with the electrochromic shifts attributed to Chl_D1 upon Q_A^? formation, indicates that in the T179H-PSII and in the WT*3-PSII, the Chl_D1 itself is the chlorophyll that is first damaged by ¹O₂, whereas in the T179V-PSII a more red chlorophyll is damaged, the identity of which is discussed. Thus, Chl_D1 appears to be one of the primary damage site in recombination-mediated photoinhibition. Finally, changes in the absorption of Chl_D1 very likely contribute to the well-known electrochromic shifts observed at ~430?nm during the S-state cycle.     

Alterations to plasma membrane lipid contents affect the biophysical properties of erythrocytes from individuals with hypertension

Genetic and environmental factors may contribute to high blood pressure, which is termed essential hypertension. Hypertension is a major independent risk factor for cardiovascular disease, stroke and renal failure; thus, elucidation of the etiopathology of hypertension merits further research. We recently reported that the platelets and neutrophils of patients with hypertension exhibit altered biophysical characteristics. In the present study, we assessed whether the major structural elements of erythrocyte plasma membranes are altered in individuals with hypertension. We compared the phospholipid (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, sphingosine) and cholesterol contents of erythrocytes from individuals with hypertension (HTN) and healthy individuals (HI) using LC/MS-MS. HTN erythrocytes contained higher phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine contents and a lower cholesterol content than HI erythrocytes. Furthermore, atomic force microscopy revealed important morphological changes in HTN erythrocytes, which reflected the increased membrane fragility and fluidity and higher levels of oxidative stress observed in HTN erythrocytes using spectrophotofluorometry, flow cytometry and spectrometry. This study reveals that alterations to the lipid contents of erythrocyte plasma membranes occur in hypertension, and these alterations in lipid composition result in morphological and physiological abnormalities that modify the dynamic properties of erythrocytes and contribute to the pathophysiology of hypertension.     

小切口囊外摘除术与超声乳化吸除术治疗老年白内障的疗效

目的:比较小切口囊外摘除术与超声乳化吸除术治疗老年白内障的临床疗效。方法:选择2014年3月-2015年3月在我院接受治疗的老年白内障患者100例,根据手术方式不同分为两组,每组50例。观察组采用小切口非超声乳化囊外摘除术,对照组采用超声乳化白内障吸除术。观察并比较两组患者围手术期眼压变化、视力恢复情况以及并发症的发生情况。结果:观察组术后2 h、6 h、12 h及24 h眼压均低于对照组,差异有统计学意义(P0.05);术后48 h两组眼压比较,差异无统计学意义(P0.05)。观察组术后1周视力高于对照组,差异有统计学意义(P0.05);术后1个月、3个月两组视力比较,差异无统计学意义(P0.05)。观察组术后并发症的发生率低于对照组,差异具有统计学意义(P0.05)。结论:小切口囊外摘除术治疗老年白内障具有围术期眼压升高慢、术后视力恢复快、并发症少等特点,值得临床推广应用。     

Effect of wheat dried distillers grains and enzyme supplementation on growth rates,feed conversion ratio and beef fatty acid profile in feedlot steers

The objectives of this study were to determine: (1) the effect of wheat dried distillers grain with solubles (DDGS) inclusion, and (2) dietary feed enzyme (FE; Econase XT) supplementation in a finishing diet containing wheat DDGS on fatty acid profile of the pars costalis diaphragmatis muscle of beef cattle. A total of 160 crossbred yearling steers with initial BW of 495±38 kg were blocked by BW and randomized into 16 pens (10 head/pen). The pens were randomly assigned to one of the four treatments: (1) control (CON; 10% barley silage and 90% barley grain-based concentrate, dry matter (DM) basis); (2) diet containing 30% wheat DDGS in place of barley grain without FE (WDG); (3) WDG diet supplemented with low FE (WDGL; 1 ml FE/kg DM); and (4) WDG diet supplemented with high FE (2 ml FE/kg DM). The pars costalis diaphragmatis muscle samples were collected from cattle at slaughter at the end of the finishing period (120 days) with a targeted live weight of 650 kg. No differences in organic matter intake, final BW and average daily gain were observed among treatments. However, steers fed WDG had greater (P<0.01) feed conversion ratio than those fed CON, and increasing FE application in wheat DDGS-based diets tended (P<0.10) to linearly decrease feed conversion ratio. In assessing the effects of including WDG diets without FE, concentration of total polyunsaturated fatty acids (PUFA) in muscle tended to be greater (P<0.10) for steers fed WDG than steers fed CON. In addition, inclusion of wheat DDGS into the diet increased (P<0.05) concentration of CLA and vaccenic acid (VA) in muscle and also resulted in a higher (P<0.05) ratio of n-6/n-3 PUFA compared with that from steers fed CON diet. Increasing FE application in wheat DDGS-based diets did not modify the concentrations of individual or total fatty acids. These results suggest that inclusion of wheat DDGS in finishing diets may improve fatty acid profile of beef muscle which could benefit human health.     

术后早期肠外联合肠内营养对老年进展期胃癌患者预后效果分析

目的:探讨术后早期肠外联合肠内营养对老年进展期胃癌临床早期预后的影响。方法:选择106例老年进展期胃癌患者,随机分为观察组56例和对照组50例,术后分别给予肠外联合肠内营养和肠外营养支持,观察2组患者术前术后C反应蛋白、血清清蛋白(ALB)、前白蛋白和血红蛋白(Hb)、肛门排气时间、并发症、住院时间及疲劳指数。结果:观察组在术后CRP水平下降优于对照组(P0.05),观察组肛门排气时间、并发症、住院时间及疲劳指数均优于对照组(P0.05),但术后血清清蛋白(ALB)、前白蛋白和血红蛋白(Hb)比较无明显差异。结论:术后早期肠外联合肠内营养减轻老年进展期胃癌患者术后的应激反应,减少并发症,促进恢复,改善早期预后。     

Clinical and molecular features and therapeutic perspectives of spinal muscular atrophy with respiratory distress type 1

Spinal muscular atrophy with respiratory distress (SMARD1) is an autosomal recessive neuromuscular disease caused by mutations in the IGHMBP2 gene, encoding the immunoglobulin μ‐binding protein 2, leading to motor neuron degeneration. It is a rare and fatal disease with an early onset in infancy in the majority of the cases. The main clinical features are muscular atrophy and diaphragmatic palsy, which requires prompt and permanent supportive ventilation. The human disease is recapitulated in the neuromuscular degeneration (nmd) mouse. No effective treatment is available yet, but novel therapeutical approaches tested on the nmd mouse, such as the use of neurotrophic factors and stem cell therapy, have shown positive effects. Gene therapy demonstrated effectiveness in SMA, being now at the stage of clinical trial in patients and therefore representing a possible treatment for SMARD1 as well. The significant advancement in understanding of both SMARD1 clinical spectrum and molecular mechanisms makes ground for a rapid translation of pre‐clinical therapeutic strategies in humans.