Rh-SAA介导3T3-LI脂肪细胞胰岛素抵抗机制的研究

目的:通过检测Rh-SAA对3T3-LI脂肪细胞的JNK活化及JNK抑制剂干预下Rh-SAA对3T3-LI脂肪细胞胰岛素敏感性的影响,探讨Rh-SAA介导胰岛素抵抗的机制.方法:实验分3组,第一组为无Rh-SAA干预的对照组,第二组为20 μg/mL Rh-SAA干预脂肪细胞组(RhvSAA组),第三组在20μg/mL Rh-SAA干预前12 h,予JNK抑制剂SP600 125 50 μmol/L预处理(以下称JNK抑制剂组),培养48 h后,采用3H-2-DG摄入法检测细胞对葡萄糖的转运率,采用免疫印迹了解JNK的活化程度.结果:与对照组比较,20μg/mL Rh-SAA处理脂肪细胞48 h后葡萄糖的摄取能力下降了26%(P<0.01).JNK抑制刺组较Rh-SAA处理组葡萄糖摄取增加了15%(P<0.05);对照组、Rh-SAA组和JNK抑制荆组的p-JNK蛋白表达量分别为100%、166%和107%.Rh-SAA组与对照组比较,JNK的磷酸化程度增加了66%(P<0.01):JNK抑制刺组与Rh-SAA组比较差异无显著性(P<0.01),与时照组比较差异无显著性(P>0.05).结论:JNK信号通路的激活可能是Rh-SAA介导脂肪细胞胰岛素抵抗的关键信号分子.提示干预JNK的活性有望成为治疗胰岛素抵抗相关疾病的有效手段.     

罗格列酮对肿瘤坏死因子-α诱导3T3-L1脂肪细胞急性血清淀粉样蛋白A表达的影响

目的:观察罗格列酮时肿瘤坏死因子-α(TNF-α)诱导3T3-L1脂肪细胞急性血清淀粉样蛋白A(A-SAA)表达的影响.方法:用不同浓度TNF-α(5、10、20μg/mL)处理3T3-L1脂肪细胞48 h,20μg/mL TNF-α处理不同时间(6、12、24、48 h)及罗格列酮预处理的3T3-L1脂肪细胞与20μg/mL TNF-α作用48 h后,用ELISA法检测各组A-SAA的表达.结果:TNF-α能显著促进3T3-L1脂肪细胞A-SAA的表达,呈剂量和时间依赖方式;罗格列酮能部分减低TNF-α对3T3-L1脂肪细胞A-SAA表达的促进作用.结论:TNF-α可以通过促进3T3-L1脂肪细胞A-SAA的表达和分泌,参与胰岛素抵抗及血管并发症的形成;罗格列酮可部分减低TNF-α对3T3-L1脂肪细胞A-SAA表达的促进作用而发挥其抗炎、抗胰岛素抵抗及抗动脉粥样的作用.     

单核细胞趋化因子-1对小鼠3T3-L1脂肪细胞B族Ⅰ型清道夫受体表达的影响

目的:观察单核细胞趋化因子-1( MCP-I)对小鼠3T3-LI脂肪细胞B族I型清道夫受体(SR-BI)膜蛋白表达的影响.方法:3T3-LI前脂肪细胞应用"鸡尾酒"法:0.5 mmol/L 1-甲基-3-异丁基黄嘌呤、1 umol/L地塞米松和10 mg/L胰岛素诱导分化成熟,油红O染色法鉴定;将诱导分化成熟的3T3-L1脂肪细胞应用MCP-1按照不同浓度及时间进行干预,分为浓度梯度组:分别加入MCP-10 ng/mL、20 ng/mL、40 ng/mL、80 ng/mL,各作用48 h;时间梯度组:分别加入MCP-1 40ng/mL各作用Oh、24 h、48 h、72 h.流式细胞仪分别测定各组细胞表面SR-BI表达.结果:(1)3T3-L1前脂肪细胞诱导分化至第9~10 d,油红O染色示90%以上可见明显脂滴,分化为成熟脂肪细胞.(2)流式细胞仪浓度梯度组结果示:与MCP-10 ng/mL组相比,20 ng/mL、40 ng/mL、80 ng/mL组细胞表面SR-BI表达均下降,差异均有统计学意义(P均<0.01);流式细胞仪时间梯度组结果示:与MCP-1Oh组相比,48 h和72 h组细胞表面SR-BI表达亦均下降,差异亦均有统计学意义(P均<0,01).结论:MCP-1干预3T3-L1脂肪细胞后,SR-BI细胞表面SR-BI的表达呈浓度依赖性和时间依赖性减少,MCP-1抑制3T3-L1脂肪细胞SR-BI细胞表面SR-BI的表达.     

罗格列酮对3T3-L1脂肪细胞胰岛素抵抗的作用

【目的】探讨罗格列酮对脂肪细胞胰岛素抵抗的影响。【方法】培养3T3-L1前脂肪细胞,采用地塞米松诱导3T3-L1脂肪细胞建立胰岛素抵抗模型,检测细胞培养基中葡萄糖浓度,同时观察罗格列酮对脂肪细胞葡萄糖转运子4（GLUT4）mRNA表达的影响。【结果】在DMEM高糖培养基中,罗格列酮能明显增加胰岛素抵抗3T3-L1脂肪细胞培养基中的葡萄糖消耗量,并可使GLUT4 mRNA表达升高,增强对胰岛素的敏感性。【结论】罗格列酮明显上调抵抗脂肪细胞GLUT4的表达,改善胰岛素抵抗。     

类胰岛素样生长因子1对3T3-L1前脂肪细胞增殖、分化的作用

目的:证实类胰岛素样生长因子1对3T3-L1前脂肪细胞增殖、分化的作用,并摸索该细胞因子对3T3-L1前脂肪细胞增殖、分化作用的最佳质量浓度。方法:实验于2004-03/2004-07在辽宁医学院科学实验中心完成。实验材料:小鼠胚胎3T3-L1前脂肪细胞株由ATCC提供,购于上海中科院生命科学院;类胰岛素样生长因子1购于美国Biological公司。实验方法:对照组为标准的高糖DMEM培养基,实验组为含有1,5,10,20,50,100μg/L类胰岛素样生长因子1的高糖DMEM培养基。用含体积分数为0.1胎牛血清的高糖DMEM培养基在37℃、体积分数为0.05 CO2的孵箱内培养3T3-L1前脂肪细胞,每48h换液1次。实验评估:在倒置显微镜下观察类胰岛素样生长因子1作用前后3T3-L1前脂肪细胞的生长情况及形态学改变。待细胞铺满瓶底后,应用流式细胞仪检测细胞周期,应用噻唑蓝法测定3T3-L1前脂肪细胞增殖率:增殖率=实验组A值/对照组A值×100%,采用油红O染色提取法测定3T3-L1前脂肪细胞内脂肪含量增长率:增长率=实验组B值/对照组B值×100%。结果:①倒置显微镜下观察分化前3T3-L1前脂肪细胞呈梭形,胞浆内无脂滴,分化后3T3-L1前脂细胞呈圆形,胞浆内含有大量的脂滴,脂滴聚集于核周,被油红O染成橙红色,形成“戒环”样的形态。②噻唑蓝法检测结果和油红O染色提取法检测结果均显示,不同质量浓度类胰岛素样生长因子1对3T3-L1前脂肪细胞增殖、分化的作用,与空白对照组相比差异显著[培养1d:(1.18±0.02)%,(1.29±0.01)%,(1.35±0.03)%,(1.47±0.04)%,(1.46±0.03)%,(1.47±0.05)%,(1.00±0.01)%;培养2d:(1.40±0.03)%,(1.56±0.04)%,(1.67±0.02)%,(1.82±0.05)%,(1.81±0.02)%,(1.82±0.09)%,(1.00±0.01)%,P<0.05],20μg/L类胰岛素样生长因子1对3T3-L1前脂肪细胞增殖、分化的作用最为明显(P=0.0382);流式细胞仪分析结果与噻唑蓝法及油红O染色提取法基本一致。结论:体外细胞培养实验表明,类胰岛素样生长因子1对3T3-L1前脂肪细胞的增殖、分化有明显促进作用,其促进作用与质量浓度并非正比,而是达到一定的质量浓度后,其促进作用不再增加,而这个质量浓度接近本实验的最佳质量浓度值,即20μg/L。     

蚕丝支架与3T3-L1前脂肪细胞生物相容性的体外实验(英文)

背景:蚕丝是天然制品,其力学性能及生物相容性优于传统人工合成的可降解高分子材料,在医疗领域中已获得了广泛的应用而受到关注.目的:观察蚕丝对3T3-L1前脂肪细胞吸附作用及蚕丝对3T3-L1前脂肪细胞形态和功能的影响.方法:取原料蚕丝和用胰酶消化后的蚕丝任意缠绕成网状立体构型纤维条索,架空固定在自制的不锈钢支架上,支架网孔70～200 μm,厚200-300 μm,孔隙率为20%.消化后的蚕丝三维支架放入24孔培养板中,将浓度为6×10L~(-1)的3T3-L1前脂肪细胞悬液每孔滴入3滴,每孔细胞数量为1×10~7个.悬空孵育4 h,待细胞充分吸附在支架上后加入培养液,令细胞完全浸没,隔两三天换半液,培养1～4周.结果与结论:①倒置显微镜观察3T3-L1前脂肪细胞-蚕丝复合物可见细胞伸出细长的突起沿着蚕丝不断向前迁移延伸,细胞首尾相互融合,渐渐连成一片分布于蚕丝网眼内.②扫描电镜观察3T3-L1前脂肪细胞-蚕丝复合物可见细胞与支架紧密贴附,适度伸展,并有基质分泌.提示蚕丝对3T3-L1前脂肪细胞具有良好的吸附作用,并能维持3T3-L1前脂肪细胞正常形态和功能.     

3T3-L1前脂肪细胞的体外培养及胰岛素样生长因子1对其增殖、分化的作用

背景：前脂肪细胞是一类具有增殖和向脂肪细胞分化潜力的特异化的前体细胞，如果能够找到可以强力促进前脂肪细胞增殖和分化的因子或药物，在脂肪组织移植的同时使用，则有希望提高脂肪组织的移植效果。目的：摸索体外培养经典的3T3-L1前脂肪细胞的最佳培养环境并积累培养经验，观察胰岛素样生长因子1对3T3-L1前脂肪细胞增殖、分化的影响，并探求胰岛素样生长因子1的最佳作用剂量。设计、时间及地点：以细胞为对象的对照观察实验，于2007—10／2008-02在辽宁医学院科学实验中心完成。材料：3T3-L1前脂肪细胞株购于上海中科院生命科学院；胰岛素样生长因子1购于美国Biological公司。方法：根据3T3一L1前脂肪细胞的体外培养条件分为6组：空白对照组应用含体积分数为0．1的胎牛血清的标准高糖DMEM培养基培养；各实验组分别应用含有5，10，20，50，100ug／L胰岛素样生长因子1的含体积分数为0．1的胎牛血清的高糖DMEM培养基培养。主要观察指标：倒置显微镜下观察各组3T3-L1前脂肪细胞的生长、增殖及分化情况并拍照记录。待细胞铺满瓶底达到单层汇合时，应用流式细胞仪检测细胞周期，应用四甲基偶氮唑盐比色法测定3T3-L1前脂肪细胞的增殖率；应用油红O染色提取法测定3T3-L1前脂肪细胞内脂肪含量的增殖率。结果：①倒置显微镜下观察分化前3T3-L1前脂肪细胞呈梭形，胞浆内无脂滴，分化后3T3-L1前脂细胞呈圆形，胞浆内含有大量的脂滴，脂滴聚集于核周，被油红O染成橙红色，形成“戒环”样形态。②四甲基偶氮唑盐比色法和油红O染色提取法检测结果均显示，不同剂量的胰岛素样生长因子1组中3T3．L1前脂肪细胞的增殖率及细胞内脂肪含量的增殖率均高于空白对照组（P〈0．05），胰岛素样生长因子120ug／L组对3T3-L1前脂肪细胞的增殖、分化作用最为明显（P〈0．05）；流式细胞仪的分析结果与四甲基偶氮唑盐比色法及油红O染色提取法的检测结果基本一致。结论：体外细胞培养实验表明，胰岛素样生长因子1对3T3-L1前脂肪细胞的增殖、分化有明显促进作用，其促进作用与浓度并非成正比，而是达到一定剂量后，其促进作用不再增加，而这个剂量接近本实验的最佳剂量值，即20ug/L。     

大黄素对脂肪细胞水通道蛋白-7表达的调节效应与其机制研究

目的观察大黄素对脂肪细胞水通道蛋白-7(AQP7)表达的调节效应并探讨其可能机制。方法成熟的3T3-L1前脂肪细胞分为5组,不同浓度大黄素组(1μM、10μM、50μM),空白对照组(不加药,加入同等体积二甲基亚砜),阳性对照组(吡格列酮10μM)干预24 h。分析大黄素对3T3-L1前脂肪细胞的分化影响,采用MTT法检测12h、24 h、48 h脂肪细胞活力。3T3-L1脂肪细胞诱导分化成熟后构建3T3-L1脂肪细胞胰岛素抵抗模型,分为5组,酶比色法测定甘油及葡萄糖摄取量。用Western Blot分析脂肪细胞中AQP7、过氧化物体增殖剂活化受体γ(PPAR-γ)表达量。结果大黄素组与阳性对照组OD值、3T3-L1脂肪细胞胰岛素抵抗模型甘油及葡萄糖摄取率及脂肪细胞中AQP7与PPAR-γ表达量显著高于空白对照组(P0.05),并且大黄素组呈现剂量依赖性,但大黄素组中浓度与阳性对照组之间无显著性差异(P0.05)。大黄素浓度在1~50μM时,3T3-L1前脂肪细胞活力均≥0.95,且浓度为10μM时,3T3-L1前脂肪细胞活力1。结论大黄素能够促进脂肪细胞分化,增加脂肪细胞同时对甘油及葡萄糖摄取,既能改善胰岛素抵抗又不增加体重,并且存在剂量依赖性。     

牛磺酸对3T3-L1前脂肪细胞分化的影响

目的:有研究发现,喂食牛磺睃的糖尿病鼠脂肪细胞摄糖的能力增加,但牛磺酸是否能影响脂肪细胞分化,目前还尚不清楚.本实验观察牛磺酸对3T3-L1前脂肪细胞分化的影响,并探讨牛磺酸影响3T3-L1前脂肪细胞分化的机制.方法:实验于2006-07/09在中南大学湘雅三医院实验中心完成.①实验材料:实验中应用的3T3-L1细胞由中国科学院上海细胞库提供.②实验方法:将3T3-L1细胞用含体积分数为0.10胎牛血清的高糖DMEM培养液培养,内含108 u/L青霉素,80×1010U/L链霉素.细胞达汇片后,按5×107L-1密度接种于培养瓶中,应用0.5mmol/L IBMX、0.5mg/L胰岛素和1μmol/L地塞米松诱导分化,实验组加入牛磺酸,对照组未实施牛磺酸干预.油红O染色观察脂肪细胞分化情况.10, 20 mmol/L牛磺酸分别干预C3T3-L1前脂肪细胞24,48 h,抽提实验组和对照组细胞RNA及蛋白.③实验评估:采用RT-PCR及Western-blot方法观察脂肪分化相关基因的表达变化.结果:①10 mmol/L牛磺酸干预后14 d,实验组油红O染色阳性脂肪细胞明显少于对照组.②10,20 mmol/L牛磺酸分别干预3T3-L1前脂肪细胞24.48 h后,对脂肪分化相关基因Insig-2蛋白、PPAR、Insing-2、脂联素、脂联素受体、GLUT-4、AP-2 mRNA表达无明显影响.结论:牛磺酸可抑制前脂肪细胞分化,但具体机制还需要进一步研究.     

肿瘤坏死因子α和吡格列酮对3T3-L1脂肪细胞葡萄糖转运子4表达的影响

目的:观察肿瘤坏死因子α和噻唑烷二酮类药物吡格列酮对3T3-L1脂肪细胞中葡萄糖转运子4(glucose transporter4,GLUT4)mRNA和蛋白表达的影响,并了解其是否有时间依赖性。方法:实验于2005-09/2006-05在安徽医科大学病原微生物分子生物学教研室进行。对3T3-L1细胞进行培养并诱导分化为成熟的3T3-L1脂肪细胞后随机分为对照组、肿瘤坏死因子α组和吡格列酮组3组。肿瘤坏死因子α组和吡格列酮组分别加含20μg/L肿瘤坏死因子α或10-4mol/L吡格列酮培养基培养,提取干预后1,3,6d细胞总RNA和总蛋白做RT-PCR和Western-blot,测定GLUT4mRNA和蛋白的表达,以未加任何药物干预组做对照。结果:①GLUT4mRNA表达:对照组细胞为0.506±0.049;肿瘤坏死因子α组干预后1,3,6d表达低于对照组(0.465±0.039,0.410±0.010,0.320±0.019,F=17.8,P=0.001),并随干预时间呈递减关系;吡格列酮组干预后1,3,6d表达高于对照组(0.544±0.064,0.616±0.065,0.664±0.070,F=4.87,P=0.043),且与干预时间呈正比。②GLUT4蛋白的相对含量:对照组细胞为0.624±0.093;肿瘤坏死因子α组干预后1,3,6d低于对照组(0.549±0.112,0.460±0.111,0.286±0.117,F=7.39,P=0.011),且随干预时间递减;而吡格列酮组GLUT4干预后1,3,6d高于对照组(0.693±0.098,0.750±0.106,0.866±0.074,F=4.0,P=0.048),随干预时间呈递增关系。结论:①肿瘤坏死因子α可降低3T3-L1脂肪细胞中GLUT4mRNA和蛋白表达量,吡格列酮的作用与肿瘤坏死因子α相反,两者作用均呈时间依赖性。②在3T3-L1脂肪细胞中,吡格列酮可能通过增加GLUT4的表达来提高胰岛素敏感性,并可能部分拮抗肿瘤坏死因子α诱导的胰岛素抵抗。     

3-hydroxy-3-methylglutaric aciduria: Deficiency of 3-hydroxy-3-methylglutaryl coenzyme a lyase

A marked deficiency of 3-hydroxy-3-methylglutaryl coenzyme A lyase activity is present in cultured skin fibroblasts from a baby with 3-hydroxy-3-methylglutaric aciduria.     

Pharmacokinetics of 3''-fluoro-3''-deoxythymidine and 3''-deoxy-2'',3''-didehydrothymidine in rats.

Concentrations of 3'-fluoro-3'-deoxythymidine (FDT) and 3'-deoxy-2',3'-didehydrothymidine (D4T) in plasma declined in a biexponential fashion. Total clearance of D4T (1.75 +/- 0.22 liters/h/kg; mean +/- standard deviation) was significantly greater than that of FDT (1.19 +/- 0.19 liters/h/kg) owing to greater renal and nonrenal clearances of the former. Steady-state volumes of distribution of FDT (1.20 +/- 0.12 liters/kg) and D4T (1.07 +/- 0.15 liters/kg) were similar.     

Antiviral Activity of 3-Deazaguanine, 3-Deazaguanosine, and 3-Deazaguanylic Acid

3-Deazaguanine (ICN 4221), 3-deazaguanosine (ICN 4793), and 3-deazaguanylic acid (ICN 5412) represent a new class of synthetic guanine analogs having antiviral activity. In vitro, nine ribonucleic acid and seven deoxyribonucleic acid viruses were inhibited, including influenza, parainfluenza, rhino-, vesicular stomatitis, adeno-, herpes-, cytomegalo-, vaccinia, pseudorabies, and myxoma viruses. They were effective orally against influenza types A and B and parainfluenza type 1 (Sendai) virus infections in mice, with a therapeutic index of 16 against the latter two viruses. The course of herpes encephalitis was altered only when the drugs were applied directly into the brain. In addition, these drugs were effective inhibitors of Friend leukemia virus-induced splenomegaly in mice; treatment also produced extensions of life in these animals.     

Pharmacokinetics of 3''-fluoro-3''-deoxythymidine and 3''-deoxy-2'',3''-didehydrothymidine in rhesus monkeys.

3'-Fluoro-3'-deoxythymidine and 3'-deoxy-2',3'-didehydrothymidine are nucleoside analogs which inhibit human and simian immunodeficiency virus in vitro. The pharmacokinetic properties of these compounds in rhesus monkeys after intravenous, oral, and subcutaneous administration of the drug were compared. Half-lives, total clearances, and steady-state volumes of distribution of the two drugs were determined. The half-lives for the drugs by the different routes were between 0.58 and 1.4 h. Oral bioavailability of 3'-deoxy-2',3'-didehydrothymidine was incomplete, with an average of 42% +/- 15% of the dose reaching the systemic circulation. Absorption of 3'-fluoro-3'-deoxythymidine after oral administration was variable, with bioavailability ranging from 21 to 95%. Bioavailability after subcutaneous administration ranged from 59 to 77% for 3'-deoxy-2',3'-didehydrothymidine and from 52 to 59% for 3'-fluoro-3'-deoxythymidine. The ratio of concentrations in cerebrospinal fluid and serum for the drugs was about 0.15 at 1 h after drug administration and was independent of the route of administration, suggesting that a nucleoside carrier-mediated process is involved in the transport of these compounds to the central nervous system. Because of the similar metabolism of nucleoside analogs in monkeys and humans, the potential glucuronide formation was assessed. Whereas the glucuronide of 3'-fluoro-3'-deoxythymidine was readily detected in urine, the amount of 3'-deoxy-2',3'-didehydrothymidine glucuronidated was small or not detectable in one-half of the urine samples. Pharmacokinetic parameters for the two drugs were similar to each other and analogous to those for 3'-azido-3'-deoxythymidine in monkeys, suggesting that the same dose and scheduling of the drug can be used for all three compounds in prophylactic and therapeutic efficacy drug studies in rhesus monkeys.     

亚急性甲状腺炎33例临床分析

目的 探讨亚急性甲状腺炎的病因、临床表现、诊断及治疗。方法 对33例患者的病史，临床表现，实验室资料及治疗进行总结分析。结果 患病的女性多见，占78．7％，病前无上怂病史记载：所有病例均有甲状腺肿大并触痛，彩超均有甲状腺肿大伴低回声，所有患者经口服泼尼松治疗效果好。结论 为减少漏诊、误诊，对咽痛伴发热病例，按上感治疗无效且持续时间较长应警惕本病。注意触诊甲状腺有无肿痛并进行必要的辅助检查。肾上腺糖皮质激素是治疗本病唯一确切有效药物。     

3-Methylcrotonylglycine excretion in 3-hydroxy-3-methylglutaric aciduria

1. 3-Methylcrotonylglycine was identified in urine from an infant with 3-hydroxy-3-methylglutaric aciduria. 2. The concentration of 3-methylcrotonylglycine in urine was approximately one sixth of that of the other metabolite of 3-methylcrotonyl-CoA, 3-hydroxyisovaleric acid. 3. The presence of both metabolites in the infant's urine indicates an inhibition of 3-methylcrotonyl-CoA carboxylase activity in tissues of the infant.     

In-plane stimulated emission of polycrystalline CH3NH3PbBr3 perovskite thin films

Hybrid organic–inorganic lead halide perovskites have been investigated extensively within the last decades, for its great potential in efficient solar cells and as an ideal light source. Among the studies on stimulated emission (SE), the emission is either out-of-plane for polycrystalline films or in-plane with randomly aligned single microcrystals and nanowires. In this work, we revealed in-plane propagation of SE from bromine-based perovskite polycrystalline thin films (CH₃NH₃PbBr₃, or MAPbBr₃). The output from in-plane SE is an order higher than the out-of-plane emission. It is proposed that large crystalline flakes in the films lead to the in-plane lasing phenomena. The output coupling can be found at grain boundaries, intergrain gaps, and artificial structures. Simulative results support the experimental phenomenon that large crystalline grains are profitable for in-plane propagation and over 90% photons can be sufficiently outcoupled when the gap is larger than a micron. Considering the fabrication and handling convenience, we propose that the MAPbBr₃ thin films can be easily integrated for in-plane applications as the light source for photonic chips etc.

MAPbBr₃ perovskite thin film contains large crystal flakes, which support the in-plane stimulated emission and its propagation within these polycrystalline films. The emission scatters at the natural or artificial edge of the film.     

3-Hydroxy-3-methylglutaric aciduria: a new assay of 3-hydroxy-3-methylglutaryl-CoA lyase using high performance liquid chromatography

A new assay has been developed for 3-hydroxy-3-methylglutaryl-CoA lyase, the final enzyme in the leucine degradative pathway. The assay was performed by incubating lysates of fibroblasts with [glutaryl-3-¹⁴C](d,l)-3-hydroxy-3-methylglutaryl coenzyme A. The products were analysed by high performance liquid chromatography with continuous liquid scintillation counting. This provided simultaneous identification and quantification of one of the enzymatic products, [3-¹⁴C] acetoacetic acid. The mean 3-hydroxy-3-methylglutaryl-CoA lyase activity in fibroblasts from five controls was 732 ± 81 (SD) pmol/min · mg protein. Using this assay, we have studied skin fibroblasts cultured from a patient with 3-hydroxy-3-methylglutaric aciduria and found 3% of normal 3-hydroxy-3-methylglutaryl-CoA lyase activity. The activities in skin fibroblasts cultured from the parents were 46 and 53% of control activity which is consistent with heterozygocity. Kinetic studies of 3-hydroxy-3-methylglutaryl-CoA lyase in skin fibroblasts cultured from two normal subjects yielded K_m values of 14.4 and 18.8 μmol/l for 3-hydroxy-3-methylglutaryl-CoA.     

Low temperature scintillation performance of a Br-doped CH3NH3PbCl3 single-crystalline perovskite

Time response and light yield are two of the most important features of a scintillation detector, and are mostly determined by the luminescence properties of the scintillator. Here we have investigated the radioluminescence (RL) characteristics of a single-crystalline hybrid lead halide perovskite at both room temperature and low temperature. A dual-channel single photon correlation (DCSPC) system with a vacuum chamber is employed for the measurement. A rise time faster than 100 ps and several times enhancement of the crystal scintillation performances at low temperature have been observed. These behaviors demonstrated that bulk solution-grown single crystals of hybrid lead halide perovskites (MAPbCl₃ and Br-doped MAPbBr_0.08Cl_2.92, where MA = CH₃NH₃) can serve as stable scintillating materials for pulsed gamma detectors. In addition, this work provides a pathway for perovskite application and also attracts attention to investigating low-temperature scintillators.

Time response and light yield are two of the most important features of a scintillation detector, and are mostly determined by the luminescence properties of the scintillator.