The natural history of untreated phenylketonuria over 20 years

Fifty-one adults with untreated phenylketonuria (PKU), have been reviewed after a 20 year interval, at ages ranging from 28.8 to 71.8 years. Five died of causes unrelated to PKU. Three severely affected individuals had shown a progressive loss of motor function and three had developed epilepsy, bringing the total with this problem to 12. No loss of abilities was apparent in 41 patients. Other health problems, including cataracts, were not frequent. Serum phenylalanine levels had decreased over the 20 year period. Untreated PKU does not generally cause progressive loss of abilities during adult life.     

Linear relationship between the maintenance of hippocampal long-term potentiation and retention of an associative memory.

The hypothesis that the maintenance or decay of an associative memory trace after an extended retention interval is a function of the residual strength of the synapses originally strengthened during learning was examined in a classical conditioning paradigm in which high-frequency stimulation of a hippocampal input--the medial perforant path--served as a conditioned stimulus. Rats received perforant path stimulus-foot shock pairings while engaged in a previously acquired food-motivated lever-pressing task. Conditioned suppression of lever pressing was the behavioral measure of learning and retention of the association. Stimulus trains to the perforant path at an intensity above the threshold for eliciting a population spike induced long-term potentiation of synaptic transmission in the dentate gyrus. Synaptic potentials recorded extracellularly in the dentate gyrus were subsequently monitored for 31 days to examine quantitatively the decay of synaptic potentiation, a period after which retention of the learned association was assessed. All rats learned the association to a similar extent and displayed equivalent amounts of long-term potentiation by the end of conditioning. A slowly decaying function of synaptic potentiation was observed in remembering rats, i.e., rats with high retention performance after the 31-day learning-to-retention interval, while forgetting was associated with a rapid decay of long-term potentiation. Behavioral performance at the long-term memory test was linearly correlated with the amplitude of long-term potentiation maintained just prior to the retention test. The results favor the hypothesis that long-term associative memory depends, at least in part, on the maintenance of elevated synaptic strengths in the pathway activated during learning and suggest a role for the lasting component of long-term potentiation in the maintenance of memory.     

Independent learning among general practice trainees: an initial survey

Self-directed learning is a natural way for adults to learn. Vocational training for general practice is a preparation for unsupervised clinical work that will be supported, in the main, by continuing medical education. This study uses the Self-Directed Learning Readiness Scale to investigate factors influencing readiness for such learning among a sample of general practice trainees. Three principal factors emerged from analysis: enjoyment and enthusiasm for learning; a positive self-concept as a learner and a factor suggesting the possibility of a 'reproducing' orientation to learning. These factors may reflect approaches to learning in general rather than these adopted for professional learning, but offer helpful pointers for the development of both vocational training and of continuing medical education.     

Auditory Perception and the Control of Spatially Coordinated Action of Deaf and Hearing Children

From birth onwards, auditory stimulation directs and intensifies visual orientation behaviour. In deaf children, by definition, auditory perception cannot take place and cannot, therefore, make a contribution to visual orientation to objects approaching from outside the initial field of view. In experiment 1, a difference in catching ability is demonstrated between deaf and hearing children (10-13 years of age) when the ball approached from the periphery or from outside the field of view. No differences in catching ability between the two groups occurred when the ball approached from within the field of view. A second experiment was conducted in order to determine if differences in catching ability between deaf and hearing children could be attributed to execution of slow orientating movements and/or slow reaction time as a result of the auditory loss. The deaf children showed slower reaction times. No differences were found in movement times between deaf and hearing children. Overall, the findings suggest that a lack of auditory stimulation during development can lead to deficiencies in the coordination of actions such as catching which are both spatially and temporally constrained.     

治疗血浓度下抗癫(癎)药对未成熟脑发育影响的实验研究

目的 探讨抗癫(癎)药物(AEDs)在治疗血浓度下对未成熟脑发育的影响.方法 以AEDs血浓度达到临床治疗稳态血浓度为实验剂量,设立健康幼鼠及成年SD大鼠氯硝西泮(CNP)、苯巴比妥(PB)、丙戊酸(VPA)、托吡酯(TPM)实验组及正常对照组(各18只).AEDs灌胃5周,于停药后次日、2周及1个月末,行Morris水迷宫及穿梭箱测试.停药当天记录体重、脑重,海马及额叶组织行苏木素-伊红(HE)、尼氏染色及电镜观察.结果 (1)停药后次日及2周的穿梭箱实验,幼鼠CNP和PB组逃避潜伏期明显长于对照组.即使停药后1个月,幼鼠CNP[(6.05±2.04)s]及PB组[(5.81±1.75)s]与对照组的差异仍有统计学意义[(4.75±2.43)s,P＜0.01].而停药后2周,成年鼠各AEDs组与对照组已无差异;(2)Morris水迷宫实验,分别于停药后次日、2周及1个月,幼鼠CNP和PB组登平台潜伏期均长于对照组.而成年鼠各组登平台潜伏期于停药后2周已无差异;(3)幼鼠CNP组脑重(1.67±0.04)g,PB组脑重(1.66±0.04)g,较对照[(1.75±0.06)g]轻;(4)神经元广泛变性坏死,神经细胞数[CNP组为(76.87±18.60)个/200倍视野,PB组(72.60±17.26)个/200倍视野]较对照少[(109.13±33.73)个/200倍视野,P＜0.01];(5)停药1个月后,PB组幼鼠神经元超微结构仍异常.结论 长期服用PB、CNP可引起未成熟脑学习记忆功能及脑组织病理学持续异常,PB对未成熟脑的损伤存在可能是不易恢复的.     

"在线期刊-写作-讨论"结合教学与临床医学教育

以参加教学改革的(01)口腔大专2个班90人为实验组，以采取传统授课方式的(00)口腔大专2个班96人为对照组，实验组采用问卷调查，将实验组和对照组课后对授课内容进行测试的成绩进行横向对比，结果表明与“在线期刊-写作-讨论”结合的临床课教学方式对培养医学生的临床思雄能力、自学能力、解决问题的能力、学生自我表达能力、收集资料能力、文字表达能力等比传统教学方式有明显的提高，对提高临床医学专业专科医学生综合素质有明显的效果。     

多巴胺受体的结构和功能

多巴胺是大脑中含量最丰富的儿茶酚胺类神经递质。多巴胺作为神经递质调控中枢神经系统的多种生理功能。多巴胺系统调节障碍涉及帕金森病，精神分裂症，Tourette综合征，注意力缺陷多动综合征和垂体肿瘤的发生等。本文综述了多巴胺受体的共同特征和各个受体的独特特征，以及它们在中枢神经系统的分布和功能，重点强调了多巴胺受体与学习记忆的关系。     

农村公共卫生投融资机制存在的问题及对策

当前,农村公共卫生投融资规模不能适应农村居民的卫生服务需要,投融资结构不合理,致使投融资效果不佳,不利于农村卫生事业的发展。为此,需要从四个方面改革农村公共卫生投融资机制:一是要建立健全国家财政投资保障制度,发挥财政在农村公共卫生投资中的主体作用;二是要改革运行模式,拓宽融资渠道;三是要改善投资结构,优化资源配置;四是要创新管理体制,提高农村公共卫生服务能力。     

妊娠压力对大鼠子代早期空间学习记忆能力的影响

【目的】探索妊娠期精神压力对大鼠子代早期空间学习、记忆能力的影响。【方法】实验采取产前束缚压力,建立妊娠期大鼠精神压力暴露模型。然后对子代进行Morris水迷宫测试,分析妊娠期压力对子代早期学习和记忆的影响及性别间的差异,同时检测实验前、后子鼠的血清肾上腺酮的变化。【结果】①在隐蔽平台试验中,对照组的平均潜伏期较实验组短,但差异无显著性(F=0.599,P>0.05)。②在保持力试验中,对照组在原平台所在象限逗留的时间大于实验组,差异有显著性(F=4.588,P<0.05)。③子代血清肾上腺酮的测定结果表明:水迷宫测试前,实验组和对照组相比,差异无显著性(F=0.169,P>0.05);实验后,实验组血清肾上腺酮比对照组高,差异具有显著性(F=6.098,P<0.05)。【结论】①妊娠压力可导致子代学习,记忆能力的改变;②妊娠压力造成子代在应激情况下血清肾上腺酮的过度分泌。③妊娠压力对子代的影响没有明显性别差异。