Adult neurogenesis: a common strategy across diverse species

Adult neurogenesis, the generation of new neurons from adult precursor cells, occurs in the brains of a phylogenetically diverse array of animals. In the higher (amniotic) vertebrates, these precursor cells are glial cells that reside within specialized regions, known as neurogenic niches, the elements of which both support and regulate neurogenesis. The in vivo identity and location of the precursor cells responsible for adult neurogenesis in nonvertebrate taxa, however, remain largely unknown. Among the invertebrates, adult neurogenesis has been particularly well characterized in freshwater crayfish (Arthropoda, Crustacea), although the identity of the precursor cells sustaining continuous neuronal proliferation in these animals has yet to be established. Here we provide evidence suggesting that, as in the higher vertebrates, the precursor cells maintaining adult neurogenesis in the crayfish Procambarus clarkii are glial cells. These precursor cells reside within a specialized region, or niche, on the ventral surface of the brain, and their progeny migrate from this niche along glial fibers and then proliferate to form new neurons in the central olfactory pathway. The niche in which these precursor cells reside has many features in common with the neurogenic niches of higher vertebrates. These commonalities include: glial cells functioning as both precursor and support cells, directed migration, close association with the brain vasculature, and specialized basal laminae. The cellular machinery maintaining adult neurogenesis appears, therefore, to be shared by widely disparate taxa. These extensive structural and functional parallels suggest a common strategy for the generation of new neurons in adult brains.     

Agenesis of the corpus callosum: magnetic resonance imaging

Three patients who had complete agenesis and two patients who had partial agenesis of the corpus callosum (ACC) underwent magnetic resonance (MR) imaging. In addition to excellent visualization of the indirect signs of ACC, direct vivid display (short T1) of the corpus callosum on sagittal images allowed better evaluation of subtle abnormalities than has been possible with other modalities. Associated abnormalities were also well-displayed. MR is the initial procedure of choice in evaluation of the corpus callosum.     

胃重复畸形并胃胰腺损伤1例

1临床资料患儿,女性,4岁。因间断性腹痛1月加重伴黑便15d,呕吐2d入院。患儿病前无明确外伤史,其母于入院前15d发现左膝部有损伤痕,已愈合,行腹部B超检查,提示肝胆肾正常,胰大小正常,边界清,实质回声均匀,主胰管不扩张,肝前区肝肾夹角及脾肾夹角可见53mm的液性暗区,内见肠管蠕动     

载脂蛋白B基因EcoRI、XbaI、MspI及载脂蛋白AI基因-75bp、+83bp位点多态性与哈萨克族血脂异常的关系

目的:分析载脂蛋白B(apoB)基因EcoRI、XbaI、MspI位点和载脂蛋白AI(apoAI)基因-75bp、+83bp位点多态性与哈萨克族(哈族)人血脂异常的关系。方法:采用聚合酶链式反应-限制性片段长度多态性分析法检测275例哈族血脂异常患者(血脂异常组)和252例哈族血脂正常对照者(对照组)的apoB基因EcoRI、XbaI、MspI位点和apoAI基因-75bp、+83bp位点多态性。检测甘油三酯、血浆总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)、apoB、apoAI的水平。结果:(1)各个位点各基因型及等位基因频率在两组之间差异无显著性。(2)血脂异常组和对照组各基因型联合的总体分布不同(χ2=19.26,P<0.05)。E+-/X--/Ms++/M1/M2(联合10)的比率在血脂异常组(45/275)显著高于对照组(22/+-++252,χ2=5.37,P<0.05)。E++/X+-/Ms+-/M1/M2(联合11)的比率在血脂异常组(30/275)显著高于对照组+-++(13/252,χ2=4.94,P<0.05)。(3)血脂异常组中基因型联合10和11(基因型联合10～11)的TC均值显著高于本组中除基因型联合10及11(基因型联合1～9)的均值,apoAI/apoB均值显著低于本组中基因型联合1～9的均值。对照组中基因型联合10～11的apoAI/apoB水平也显著低于本组中基因型联合1～9。(4)E++/X+-/Ms++/M1/M2(基因型联合2)的TC在两组中都分别低于基因型联合10～11,apoAI/apoB在两组+-+-中都分别高于基因型联合10～11。(5)apoAI/apoB无论在血脂异常组还是在对照组都与TC、LDL-C负相关,与HDL-C正相关。结论:apoB基因EcoRI、XbaI、MspI位点和apoAI基因-75bp、+83bp各位点基因型多态联合中,基因型联合10及11与哈族人血脂异常相关。基因型联合2可能是预防血脂异常的因素。其中的机制可能与载脂蛋白基因变异引起apoAI/apoB的改变进而引起血脂的变化有关。     

Weight loss and incretin responsiveness improve glucose control independently after gastric bypass surgery

Background: The aim of the present study was to determine the mechanisms underlying Type 2 diabetes remission after gastric bypass (GBP) surgery by characterizing the short‐ and long‐term changes in hormonal determinants of blood glucose. Methods: Eleven morbidly obese women with diabetes were studied before and 1, 6, and 12 months after GBP; eight non‐diabetic morbidly obese women were used as controls. The incretin effect was measured as the difference in insulin levels in response to oral glucose and to an isoglycemic intravenous challenge. Outcome measures were glucose, insulin, C‐peptide, proinsulin, amylin, glucagon, glucose‐dependent insulinotropic polypeptide (GIP), glucagon‐like peptide‐1 (GLP‐1) levels and the incretin effect on insulin secretion. Results: The decrease in fasting glucose (r = 0.724) and insulin (r = 0.576) was associated with weight loss up to 12 months after GBP. In contrast, the blunted incretin effect (calculated at 22%) that improved at 1 month remained unchanged with further weight loss at 6 (52%) and 12 (52%) months. The blunted incretin (GLP‐1 and GIP) levels, early phase insulin secretion, and other parameters of β‐cell function (amylin, proinsulin/insulin) followed the same pattern, with rapid improvement at 1 month that remained unchanged at 1 year. Conclusions: The data suggest that weight loss and incretins may contribute independently to improved glucose levels in the first year after GBP surgery.     

急性缺血性卒中影像学检查的建议——美国心脏协会的科学声明（上）

卒中是一种常见、严重的疾病,仅美国每年的新发病例就高达795000例,并已成为全世界人类死亡和残疾的主要病因。10年前,重组型组织纤溶酶原激活剂（recombinant tissue plasminogen activator,rt—PA）被批准用于治疗急性缺血性卒中。rt—PA应用指南建议,应在卒中发病后3h内静脉给予rt—PA,给药前应行头部CT检查,排除颅内出血。     

急性缺血性卒中影像学检查的建议——美国心脏协会的科学声明（中）

2．3核磁共振血管成像（MRA） 2．3．1背景和方法：在头部MRI检查中常结合MRA,用于急性卒中患者病情评估以指导治疗决策的制定^[19]。日前,有几种不同的MRA技术用于脑血管成像,包括二维时间飞跃（timeof-flight,TOF）序列、三维TOF序列、