Quantitative assessment of diagnostic ability

This paper describes variables critical to diagnostic thinking that are based on research by Bordage and Grant & Marsden on the diagnostic thinking of medical students and experienced doctors. The purpose of the study is to use their findings to develop an inventory of diagnostic thinking. A 56-item diagnostic thinking inventory was initially developed; each item contains a stem followed by a 6-point, semantic differential scale. The inventory is designed to measure two aspects of diagnostic thinking: the degree of flexibility in thinking and the degree of knowledge structure in memory. The specific goal of the study is to determine which items discriminate best between weaker and stronger diagnosticians and to reduce the inventory to only those items which significantly contribute to the overall score. Thirty subjects from nine groups, each representing a distinct phase of medical education and clinical practice, participated, namely first- and third-year clinical medical students, house officers, senior house officers, registrars, senior registrars, consultants, trainees in general practice, and general practitioners, all from the UK (n = 270). Discrimination indices were calculated for each item. The revised version of the inventory contains 41 items. All the subjects found the exercise meaningful and the resulting scores showed variance and discrimination. The inventory will eventually be used to assess individual student's and clinician's diagnostic thinking and to plan ways of improving their diagnostic thinking.     

Effects of AETT-Induced Neuronal Ceroid Lipofuscinosis on Learning Ability in Rats

Abstract: The behavioral effects of ceroid-lipofuscin accumulation, induced by intraperitoneal administration of acetyl-ethyl-tetramethyl-tetralin (AETT) in Wistar rats for 3 months, were examined in the present studies. A significant increase in neuronal ceroid-lipofuscin was demonstrated neuropathologically as well as morphometrically. Although the AETT-intoxicated rats showed neither alteration of locomotor activity nor shock sensitivity, a significant impairment of learning ability, especially an acquisition trial in passive avoidance tests, was observed. Results of the present studies indicate the possibility that a diffuse lipofuscin accumulation causes a learning impairment in rats. The results also imply the possibility of a significant role of age-related lipofuscin accumulation in the dementing processes of human especially in the elderly.     

Monkey hippocampal neuron responses to complex sensory stimulation during object discrimination.

The purpose of this study was to investigate, during the performance of an object discrimination task, responses of neurons in the monkey hippocampal formation to the sight of several objects that have biological meaning, and compare these responses with those of amygdalar neurons studied previously using the same task. Neuronal activity in the hippocampal formation of conscious monkeys was recorded during performance of a task that led to presentation of familiar rewarding, familiar aversive, or unfamiliar objects. Of 864 neurons recorded in the hippocampal formation and adjacent cortices, 160 (18.5%) responded to the sight of a certain object(s). Responses to the sight of different kinds of objects were analyzed in detail. Nondifferential neurons (n = 73) responded to different objects with no significant difference in response magnitudes, and differential neurons (n = 87) responded to different objects with different response magnitudes. Of the differential neurons, 23 responded more strongly to rewarding objects than to other objects (rewarding-object-dominant neurons), but the magnitude of responses to objects did not necessarily correlates with the order of preferences to the objects as determined from observation of animal behavior. Aversive-object-dominant neurons (n = 13) responded more to aversive objects than to other objects. Unfamiliar-object-dominant neurons (n = 7) responded more to unfamiliar objects than to familiar objects. Selective neurons (n = 10) responded selectively to only one object or one category of objects. Fourteen of the rewarding- or averse-object-dominant neurons were tested in extinction or reversal trials. In 12 of 14 neurons, responses to a rewarding or aversive object did not change, or slightly weakened, in extinction or reversal trials. The results suggest the following. (1) Responses of rewarding- or aversive-object-dominant neurons may be involved in object-reward or object-aversion association. However, responses of many of these neurons might reflect past inputs to reinforcement rather than extant emotional processing. (2) Responses of unfamiliar-object-dominant neurons may be involved in recognition of objects based on their familiar or unfamiliar aspects. These results are further discussed and compared with responsiveness of amygdalar neurons.     

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.     

食管内支架置入术并发症分析及防治

目的：分析食管内钛镍记忆合金支架置入术并发症的可能原因及防治方法。方法：共52例病人，食管癌、贲门癌29例，食管胃吻合口狭窄21例，自发性食管破裂2例，共置入各种钛镍记忆合金支架54枚。随访观察3～36个月。结果：内支架置入全部成功，术后患吞咽困难症状均改善。术后出现的并发症包括支架移位3例，支架堵塞9例。吸入性肺炎3例，呕血7例，残余漏2例，疼痛和异物感24例，严重返流症状5例。经过相应的治疗，除2例大呕血患外，其余并发症均得到纠正。结论：虽然食管内钛镍记忆合金支架置入术后有不可忽视的并发症，但经过相应治疗，一般均可纠正，它是治疗食管恶性狭窄和自发性食管破裂有效的方法。     

Time course of the effects of diazepam and lorazepam on perceptual priming and explicit memory

The effects of diazepam and lorazepam on explicit memory and perceptual priming were studied 50, 130 and 300 min after drug administration. Sixty healthy volunteers were randomly assigned to one of five parallel groups (placebo, diazepam 0.2 or 0.3 mg/kg, lorazepam 0.026 or 0.038 mg/kg). The corresponding doses of benzodiazepines exerted a similar negative effect on explicit performance. Lorazepam markedly impaired priming performance, whereas the effect of diazepam was intermediate between that of placebo and that of lorazepam 0.038 mg/kg. The impairment was maximal at the theoretical peak plasma concentration. Contamination by explicit memory could account for the decrease in priming performance observed in the diazepam groups.     

镍钛记忆合金锁骨钩环抱器治疗新鲜重度肩锁关节脱位

目的 评估镍钛记忆合金锁骨钩环抱器治疗新鲜重度肩锁关节脱位的临床疗效。方法 选择16例新鲜重度肩锁关节脱位患者，其中3例合并锁骨远端骨折，应用镍钛记忆合金锁骨钩环抱器治疗并进行临床疗效观察。随访6～12个月，平均7.6个月。结果 所有患者肩关节肌肉无萎缩，外观正常，肩关节活动范围正常，x线片示无再脱位征象。采用Karlsson术后疗效分级：A级15例，B级1例。结论 镍钛记忆合金锁骨钩环抱器治疗新鲜重度肩锁关节脱位创伤小，简便易行，疗效好，对合并锁骨远端骨折病人更具有独特优点，具有临床推广应用价值。     

前额叶皮层在数字工作记忆维持中的作用:事件相关fMRI研究

目的采用事件相关功能磁共振成像(ER-fMRI)探讨前额叶皮层在工作记忆维持期的作用。方法20名正常受试者接受sternberg项目认知任务的功能磁共振成像。采用相对低负载、高负载任务。组分析方法评价维持期相对低、高负载时平均脑区激活情况;组间比较探讨高负载任务出现相关激活增加的脑区。结果维持期与双侧前额叶背外侧皮层(DLPFC)、双侧前额叶腹外侧皮层(VLPFC)、顶叶、辅助运动区(SMA)和运动前区(PMA)、视觉相关皮层激活相关,VLPFC等脑区在高负载任务中激活增加。结论工作记忆维持和操纵之间可能存在功能上的、而非神经解剖的区分。     

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。