Alterations in creatine metabolism observed in experimental autoimmune myocarditis using ex vivo proton magic angle spinning MRS

Experimental autoimmune myocarditis (EAM) in rodents is an accepted model of myocarditis and dilated cardiomyopathy (DCM). Altered metabolism is thought to play an important role in the pathogenesis of DCM and heart failure (HF). Study of the metabolism may provide new diagnostic information and insights into the mechanisms of myocarditis and HF. Proton MRS (¹H‐MRS) has not yet been used to study the changes occurring in myocarditis and subsequent HF. We aimed to explore the changes in creatine metabolism using this model and compare them with the findings in healthy animals. Myocardial function of male young Lewis rats with EAM was quantified by performing left ventricular ejection fraction (LVEF) analysis in short‐axis cine images throughout the whole heart. Inflammatory cellular infiltrate was assessed by immunohistochemistry. Myocardial tissue was analyzed using ex vivo proton magic angle spinning MRS (¹H‐MAS‐MRS). Myocarditis was confirmed histologically by the presence of an inflammatory cellular infiltrate and CD68 positive staining. A significant increase in the metabolic ratio of Tau/tCr (taurine/total creatine) obtained by ¹H‐MAS‐MRS was observed in myocarditis compared with healthy controls (21 d acute EAM, 4.38 (±0.23); 21 d control, 2.84 (±0.08); 35 d chronic EAM, 4.47 (±0.83); 35 d control, 2.59 (±0.38); P < 0.001). LVEF was reduced in diseased animals (EAM, 55.2% (±11.3%); control, 72.6% (±3.8%); P < 0.01) and correlated with Tau/tCr ratio (R = 0.937, P < 0.001). Metabolic alterations occur acutely with the development of myocarditis. Myocardial Tau/tCr ratio as detected by ¹H‐MRS correlates with LVEF and is able to differentiate between healthy myocardium and myocardium from rats with EAM. Copyright © 2015 John Wiley & Sons, Ltd.     

经脾胰岛移植治疗糖尿病大鼠的可行性

目的:探讨经脾胰岛移植治疗糖尿病大鼠的疗效及可行性,建立稳定的胰岛移植新途径。方法:实验于2004-03/2005-03在中国医科大学附属第一医院完成。实验分组:供受鼠均采用Wistar大鼠,供鼠40只,受鼠20只。受鼠随机分为移植组、糖尿病组,每组10只。并另取10只正常大鼠作为正常组,进行对照。实验过程:①受鼠造模:移植前14d,采取链尿霉素化学灼伤法(2%链尿霉素,65mg/kg,腹腔注射)造成糖尿病大鼠模型(连续3d在非禁食情况下,血糖>16.8mmol/L为造模成功)。②供鼠胰岛分离纯化:采用明尼苏达大学改良方法,原位直接灌注消化分离大鼠胰岛。消化的胰腺组织离心,经80目不锈钢筛网过滤后,采用25%,23%,20.5%,11%Ficoll和Hank’s液梯度密度离心(4℃,3000r/min×10min),于23%,11%层交界间吸取胰岛细胞。经Hank’s液洗3次,备用。③经脾胰岛移植:移植组大鼠戊巴比妥麻醉后,经左侧肋缘下切口暴露脾脏。显微镜下手检600～800当量胰岛,以1mLCMRL1066培养液稀释,用10mL注射器直接经脾缓慢输注。糖尿病对照组大鼠注射生理盐水1mL。实验评估:①胰岛双硫腙染色与计数,计算纯化率。②体外葡萄糖刺激实验检测胰岛功能。③移植术后监测血糖、血清胰岛素水平。于术后10d行静脉糖耐量实验。④术后14d切取受体大鼠肝脏和脾脏苏木精-伊红染色及Insulin-6免疫组化染色观察组织形态学变化。结果:①每只供鼠可分离300～400当量胰岛,纯度达85%～90%。②体外葡萄糖刺激实验显示胰岛素刺激指数平均为5.59±0.62,功能良好。③受体糖尿病大鼠术后3-5d空腹血糖降至3.4～5.4mmol/L(平均4.8mmol/L)。胰岛素分泌亦达到正常水平。④移植组糖耐量曲线与正常大鼠相似,K值与正常非糖尿病大鼠差异无显著性(2.802,2.3,P>0.05)。⑤受体大鼠脾脏和肝脏内可见散在的移植胰岛。结论:①移植术后3-5d移植胰岛分泌的胰岛素可使空腹血糖达到正常水平。②经脾移植克服了门静脉直接移植引起的出血和门静脉高压的缺点,移植容量可达1mL,可用10mL注射器进行输注,避免反复离心、挤压,可减少胰岛体外损失,是胰岛移植的可行途径。     

多发性硬化患者脑脊液标本收集和标本库建立的方案

<正> 迄今,多发性硬化(MS)脑脊液生物学标志物中用于临床的仅有寡克隆区带和IgG鞘内合成率,其最重要的制约因素为:生物学标志物研究所需的样本量很大,单一研究中心很难达到,因此多方合作已成为趋势。脑脊液标本的采集和保存很重要。2007年3月,欧洲MS生物学标志物协作网(BioMS-eu)在伦敦召开会议,拟定了MS患者脑脊液采集、分装、储存以及相关数据收集的方案,并于2009年12月1日在Neurology杂志发表。现简要介绍如下。 1 脑脊液标本收集及注意事项 (1) 采集量:至少12mL,采集此量不会引起低颅压。因不同段脑脊液蛋白质浓度不同,建议取最初2mL用于常规检查,其余部分混匀后     

Functional analysis of a mouse brain Elk-type K+ channel.

Members of the Ether à go-go (Eag) K+ channel subfamilies Eag, Erg, and Elk are widely expressed in the nervous system, but their neural functions in vivo remain largely unknown. The biophysical properties of channels from the Eag and Erg subfamilies have been described, and based on their characteristic features and expression patterns, Erg channels have been associated with native currents in the heart. Little is known about the properties of channels from the Elk subfamily. We have identified a mouse gene, Melk2, that encodes a predicted polypeptide with 48% amino acid identity to Drosophila Elk but only 40 and 36% identity with mouse Erg (Merg) and Eag (Meag), respectively. Melk2 RNA appears to be expressed at high levels only in brain tissue. Functional expression of Melk2 in Xenopus oocytes reveals large, transient peaks of current at the onset of depolarization. Like Meag currents, Melk2 currents activate relatively quickly, but they lack the nonsuperimposable Cole-Moore shift characteristic of the Eag subfamily. Melk2 currents are insensitive to E-4031, a class III antiarrhythmic compound that blocks the Human Ether-à-go-go-Related Gene (HERG) channel and its counterpart in native tissues, IKr. Melk2 channels exhibit inward rectification because of a fast C-type inactivation mechanism, but the slower rate of inactivation and the faster rate of activation results in less inward rectification than that observed in HERG channels. This characterization of Melk currents should aid in identification of native counterparts to the Elk subfamily of channels in the nervous system.     

Cushing syndrome: pituitary CT scanning

Proper treatment of patients with Cushing syndrome depends on knowledge of whether the condition derives from a pituitary or adrenal adenoma or an ectopic tumor that secretes adrenocorticotropic hormone (ACTH). Fifty-seven patients with Cushing syndrome were prospectively evaluated to determine whether computed tomography (CT) of the pituitary gland is useful in diagnosing or excluding an ACTH-producing adenoma and in predicting the site of the adenoma within the pituitary gland. Findings on CT scans were normal in 35 of 50 patients with surgically confirmed Cushing disease and in seven patients with ectopic ACTH-producing tumors. Of the 15 patients with Cushing disease for whom CT results were abnormal, eight had macroadenomas and seven had microadenomas. This study demonstrates a low sensitivity (30%) and low diagnostic accuracy (39%) of CT in the detection of ACTH-producing pituitary tumors and indicates the need for alternative methods of confirming the pituitary origin of excessive ACTH secretion in most patients.     

Cardiovascular variability after rilmenidine challenge: assessment of acute dosing effects by means of spectral analysis

Summary— Short-term fluctuations in blood pressure (BP) and heart rate (HR) were analysed in a group of twelve subjects with mild hypertension. Indirect finger BP was measured by a Finapres® device. The effects of an oral dose of rilmenidine (1 mg) were studied in a double-blind cross-over placebo-controlled study. Compared with placebo, rilmenidine reduced the variability of standing BP after 2 hours as estimated from the standard deviation of systolic BP which diminished by 20%. Spectral analysis of fluctuations in BP showed this reduction predominated in the mid frequency (MF) region corresponding to 10-second period oscillations, which depend on the activity of the autonomic nervous system. The average reduction in MF component for standing systolic BP was 24%. In addition the MF component for HR was reduced by 17%. This frequency domain analysis demonstrates a modified BP and HR variability profile with an acute dosing of rilmenidine. This effect being limited to the MF fluctuations in standing position orients towards an effect of the drug on the sympathetic cardiovascular control.     

Specific radioimmunochemical identification and quantitation of hemoglobins a2 and f

Hyperimmune antisera to chromatographically purified hemoglobins F and A₂, were produced in rabbits and made specific for the immunogen by adsorption with normal human hemoglobin A conjugated to cyanogen bromide-activated agarose. A radioimmunoassay was established that permitted identification and quantitation of each of these two minor hemoglobins in hemolysates containing other hemoglobin components. The quantities of hemoglobins A₂, and/or F present in hemolysates of individuals with β-thalassemia, sickle cell anemia, Hb-C disease, and other hematological disorders were determined immunochemically, and the results were compared to values obtained by microcolumn chromatography for the measurement of Hb-A₂ or with the alkali denaturation technique in quantitating Hb-F. The immunoassay procedure has a greater sensitivity than other commonly employed techniques and can detect as little as 0.05 μg of these hemoglobins.     

Sports-related muscle injuries: evaluation with MR imaging

Sports-related muscle pain is frequent in both trained and untrained persons; however, its severity and significance may be difficult to assess clinically. The authors used magnetic resonance (MR) imaging to evaluate acute strains and delayed-onset muscle soreness in sedentary subjects and postmarathon myalgia in trained runners. MR imaging documented the distribution of affected muscles and the absence of focal hematoma, fascial herniation, subsequent fibrosis, and fatty infiltration. Pain associated with strain and that occurring several days after exercise were both associated with prolongation of muscle T1 and T2. In a prospective evaluation of delayed-onset muscle soreness, abnormalities depicted at MR imaging persisted longer than symptoms by up to 3 weeks, indicating that MR imaging is sensitive to tissue alteration that is not apparent clinically. Highly trained marathon runners tended to have relatively mild abnormalities involving the myotendinous junctions.