Targeted delivery across the blood-brain barrier

The safest and most effective way of targeting drugs to the entire brain is via delivery systems directed at endogenous receptor-mediated uptake mechanisms present at the cerebral capillaries. Such systems have been shown to be effective in animal models including primates, but no clinical trials have been performed so far. This review focuses on the well-characterised transferrin and insulin receptor-targeted systems, as well as on the more recently described systems that use the low-density lipoprotein-related protein 1 receptor, the low-density lipoprotein-related protein 2 receptor (also known as megalin and glycoprotein 330) or the diphtheria toxin receptor (which is the membrane-bound precursor of heparin-binding epidermal growth factor-like growth factor). The possibilities and limitations of these systems are compared and their future for human application is discussed.     

Biomarkers for the effects of selective serotonin reuptake inhibitors (SSRIs) in healthy subjects

AIMS: Studies of novel centrally acting drugs in healthy volunteers are traditionally concerned with kinetics and tolerability, but useful information may also be obtained from biomarkers of clinical endpoints. This paper provides a systematic overview of CNS-tests used with SSRIs in healthy subjects. A useful biomarker should meet the following requirements: a consistent response across studies and drugs; a clear response of the biomarker to a therapeutic dose; a dose-response relationship; a plausible relationship between biomarker, pharmacology and pathogenesis. METHODS: These criteria were applied to all individual tests found in studies of selective serotonin reuptake inhibitors (SSRIs), performed in healthy subjects since 1966, identified with a systematic MedLine search. Separate databases were created to evaluate the effects of single or multiple dose SSRI-studies, and for amitriptyline whenever the original report included this antidepressant as a positive control. Doses of the antidepressant were divided into high- and low-dose ranges, relative to a medium range of therapeutic doses. For each test, the drug effects were scored as statistically significant impairment/decrease (-), improvement/increase (+) or no change (=) relative to placebo. RESULTS: 56 single dose studies and 22 multiple dose studies were identified, investigating the effects of 13 different SSRIs on 171 variants of neuropsychological tests, which could be clustered into seven neuropsychological domains. Low single doses of SSRIs generally stimulated tests of attention and memory. High doses tended to impair visual/auditory and visuomotor systems and subjective performance, while showing an acceleration in motor function. The most pronounced effects were observed using tests that measure flicker discrimination (improvement at low doses: 75%, medium doses: 40%, high doses: 43% of studies); REM sleep (inconsistent decrease after medium doses, decrease in 83% of studies after high doses); and EEG recordings, predominantly in alpha (decrease in 60% and 43% of studies after low and medium doses, respectively) and in theta activity (increase in 43% and 33% of studies after medium and high doses, respectively). Amitriptyline generally impaired central nervous system (CNS) functions, which increased with doses. Multiple doses caused less pronounced effects on the reported tests. The most responsive tests to amitriptyline appeared to be EEG alpha and theta, and REM sleep duration. CONCLUSIONS: SSRIs in healthy subjects appear to cause slight stimulating effects after low doses, which tend to diminish with dose. The most consistent effects were observed with flicker discrimination tests, EEG (alpha and beta bands), REM sleep duration, and subjective effects at higher doses. These effects are small compared with amitriptyline and other CNS-active drugs. Multiple dosing with SSRIs caused even fewer measurable differences from placebo, probably due to adaptive processes. SSRI-effects are best detected with a test battery that is sensitive to general CNS-stimulation, but such tests only comprise a very small portion of the close to 200 different methods that were found in current review.     

The central nervous system effects, pharmacokinetics and safety of the NAALADase-inhibitor GPI 5693

AIM: The aim was to assess the central nervous system (CNS) effects, pharmacokinetics and safety of GPI 5693, an inhibitor of a novel CNS-drug target, NAALADase which is being evaluated for the treatment of neuropathic pain. METHODS: This was a double-blind, placebo-controlled, exploratory study in healthy subjects receiving oral GPI 5693 single ascending doses of 100, 300, 750, 1125 mg with a placebo treatment randomly interspersed. An open-label, parallel extension examined the effects of food and sex on the pharmacokinetics of 750, 1125 and 1500 mg doses. Blood samples were collected for pharmacokinetic and biochemical/haematological safety analysis, vital signs, ECG and adverse event checks were performed regularly up to 48 h postdose. Postdose CNS effects were assessed using eye movements, adaptive tracking, electroencephalography (EEG), body sway and Visual Analogue Scales (VAS). RESULTS: CNS effects were mainly observed after the 1125 mg dose, showing a significant decrease of adaptive tracking performance, VAS alertness and VAS mood, and an increase of EEG occipital alpha and theta power. Gastro-intestinal (GI) adverse effects were frequent at higher doses. No clinically significant changes in vital signs or ECG were noted during any of the treatments. The therapeutically relevant concentration range (950-11 100 ng ml(-1)) as determined from animal experiments was already reached after the 300 mg dose. C(max) after the 300 mg and 750 mg dose was 2868 and 9266 ng ml(-1) with a t(1/2) of 2.54 and 4.78 h, respectively. Concomitant food intake (with the 750 mg and 1125 mg doses) reduced C(max) by approximately 66% and AUC by approximately 40%. With concomitant food intake, the dose-normalized C(max) also decreased significantly by -5.6 (CI: -2.6 to -8.7) ng ml(-1) mg(-1). The pharmacokinetic variability was largest after the 300 mg and 750 mg dose, resulting in a SD of approximately 50% of the C(max). CONCLUSION: NAALADase inhibition with GPI 5693 was safe and tolerable in healthy subjects. Plasma concentrations that were effective in the reversal of hyperalgesia in the chronic constrictive injury animal model of neuropathic pain were obtained at doses of 300, 750 and 1125 mg in the fasted state. Comcomitant food intake reduced C(max) and AUC. CNS effects and GI AEs increased in incidence over placebo only at the 1125 mg dose.     

左向右分流型先天性心脏病患儿肺功能相关研究

目的探讨左向右分流型先天性心脏病患儿心肺功能的交互作用。方法选择左向右分流型先天性心脏病患儿62例为先心组,健康体检儿童40例为对照组,进行肺功能检查与血气分析(PaO2、PaCO2、pH值)及血C-反应蛋白(CRP)测定,并进行相关性分析。结果先心组患儿的呼吸频率(RR)高于对照组,每千克体质量潮气量(VT/kg)、潮气呼吸峰流速(PTEF)、达到峰流速的时间与呼吸时间的比值(TPTEF/Te)、达到呼气峰流速时呼出的气体容积与呼气容积的比值(VPEF/Ve)水平均低于对照组;从单纯先天性心脏病到先天性心脏病合并肺炎、到合并肺炎与心力衰竭,RR水平越来越高,VT/kg、PTEF、TPTEF/Te、VPEF/Ve水平则越来越低;单纯先天性心脏病,先天性心脏病合并肺炎、合并肺炎与心力衰竭患儿与对照组比较,PaO2水平逐渐降低,CRP水平逐渐升高。结论肺功能测定能够反映左向右分流型先天性心脏病患儿心肺功能的病理生理特点,血气分析及血CRP测定能反映患儿疾病的严重程度。     

Developmental stage‐specific contribution of LGR5+ cells to basal and luminal epithelial lineages in the postnatal mammary gland

The leucine‐rich repeat‐containing heterotrimeric guanine nucleotide‐binding protein‐coupled receptor 5 (LGR5) has been identified as a marker of cycling stem cells in several epithelial tissues, including small intestine, colon, stomach and hair follicle. To investigate whether LGR5 also marks mammary epithelial stem cells, we performed in situ lineage‐tracing studies and mammary gland reconstitutions with LGR5‐expressing mammary epithelial cells. Interestingly, the LGR5 progeny population in mammary epithelium switches from the luminal to the myoepithelial compartment during the first 12 days of postnatal development, likely reflecting local changes in Wnt signalling. Together, our findings point to a stage‐specific contribution of LGR5‐expressing cells to luminal and basal epithelial lineages during postnatal mammary gland development. Copyright © 2012 Pathological Society of Great Britain and Ireland.     

梁门穴的基础研究及临床运用

本文通过复习近年来针灸对梁门穴研究的文献,归纳实验针灸学从蛋白组学、基因组学、生理学等角度对梁门穴的研究进展;基础研究也证明了梁门穴或足阳明胃经作用的特异性.梁门穴在消化系统尤其是胃部疾病运用广泛,临床运用主要集中于胃脘痛(相当于胃炎、胃溃疡等)、消化不良、单纯性肥胖等.     

基于高考和医学课程成绩的医学生学业潜力的研究

目的 通过分析临床医学专业学生的高考成绩与本科阶段的学业情况,探讨医学专业学生学业潜力与高考成绩的关系.方法 以上海第二医科大学2003级临床医学专业314名上海籍学生为研究对象,使用回归统计对其高考成绩和本科各阶段(医学前期课程、医学基础期课程与临床期课程)的学业成绩进行分析.结果 医学生的本科学业成绩与高考总成绩之间不具有相关性,而高考中的英语和语文两科成绩则与临床医学学业成绩显著相关.结论 高考总成绩对医学本科生的学业成绩没有显著影响,但高考英语和语文成绩会在一定程度上影响医学课程的成绩.     

模拟帕金森病的表达人α-synucleinA53T转基因小鼠的早期嗅觉功能观察

目的通过对表达人α-synucleinA53T的转基因小鼠嗅觉功能的检测和比较,确立一个可供研究帕金森病早期嗅觉障碍发病机制的模型。方法选取不同月龄的表达人α-synucleinA53T的转基因(TG)小鼠与同窝野生型(WT)对照小鼠;转棒试验评估10月龄TG小鼠随意运动功能是否发生变化;DAB法观察10月龄小鼠脑黑质多巴胺能神经元,进一步验证小鼠是否发生运动功能改变。通过气味鉴别及适应试验,观察小鼠对已熟悉的同种气味的短期记忆能力及适应能力,判断小鼠对陌生气味的辨别能力;通过长间隔记忆试验,检测小鼠对已经暴露过的气味在一定间隔时间后再次暴露的记忆能力;通过隐藏颗粒试验,检测小鼠对食物气味的感知能力,反映嗅觉阈值的水平。结果转棒试验和多巴胺能神经元观察结果均显示10月龄TG小鼠的随意运动功能尚未发生改变。6月龄TG小鼠出现对气味辨别能力的下降,对新旧两种气味的识别时间比较,差异无统计学意义(P=0.120);10月龄TG小鼠表现出更明显的气味识别缺陷(P=0.295)。6月龄TG小鼠寻找到食物的时限长于WT小鼠(P=0.015)。各年龄段小鼠短期记忆及适应能力均正常;但9月龄TG小鼠表现出长期(两次试验间隔时间60、80、100 min)记忆能力减退。结论表达人α-synucleinA53T的转基因小鼠在运动功能改变之前出现嗅觉障碍,表现在气味辨别、记忆、感知能力等方面,能够很好地模拟帕金森病早期嗅觉障碍的表现。