酶联免疫吸附试验中影响全自动加样系统加样准确性的因素分析

目的探讨酶联免疫吸附试验(ELISA)中使用不同容量加样针和分液高度,对全自动加样系统加样准确度和精密度的影响。方法选取10μL和100μL两种加样量,每种加样量分4个小组进行实验,分别使用不同容量(400μL和800μL)的加样针和不同分液高度(浸润和未浸润)加样,计算每组的最终加样量、均值相对误差(E)和变异系数(CV),与实际工作标准进行比较。结果10μL加样E在-37.9%~-2.8%,CV在3.29%~14.49%;100μL加样E在-1.9%~0.8%,CV在0.44%~0.95%。结论不同容量加样针和分液高度对10μL加样影响较为明显,对100μL加样影响较小,在使用全自动加样系统进行ELISA时,应当选择适当容量的加样针和分液高度。     

周围神经选择性切断治疗脑瘫性下肢痉挛

目的探讨周围神经选择性切断治疗脑瘫性下肢痉挛的效果。方法对380例脑瘫性下肢痉挛患者,根据痉挛部位不同,选择相应周围神经(包括腰骶段脊神经后根、坐骨神经、闭孔神经和胫神经)部分切断。结果术后痉挛缓解率100%,其中82例患者肌力下降,142例患者出现肢体麻木、感觉减退,随访期间均见好转。术后随访6个月～3年,随访期间痉挛缓解率为95%。95%患者行走步态好转。结论周围神经选择性切断术对治疗脑瘫性下肢痉挛是安全、有效的。     

Teaching suturing and knot-tying skills to medical students: a randomized controlled study comparing computer-based video instruction and (concurrent and summary) expert feedback

BACKGROUND: We carried out a prospective, randomized, 4-arm study including control arm, blinding of examiners to determine effectiveness of computer-based video instruction (CBVI) and different types of expert feedback (concurrent and summary) on learning of a basic technical skill. METHODS: Using bench models, participants were pre-tested on a suturing and instrument knot-tying skill after viewing an instructional video. The students were subsequently assigned randomly to 4 practice conditions: no additional intervention (control), self study with CBVI, expert feedback during practice trials (concurrent feedback), and expert feedback after practice trials (summary feedback). All participants underwent 19 trials of practice, over 1 hour, in their assigned training condition. The effectiveness of training was assessed both at an immediate post-test and 1 month later at a retention test. Performance was evaluated using both expert-based (Global Rating Scores) and computer-based assessment (Hand Motion Analysis). Data were analyzed using repeated-measures ANOVA. RESULTS: There were no differences in GRS between groups at pre-test. The CBVI, concurrent feedback and summary feedback methods were equally effective initially for the instruction of this basic technical skill to naive medical students and displayed better performance than control (control, 12.71 [10.79 to 14.62]; CBVI, 16.39 [14.38 to 18.40]; concurrent, 16.97 [15.79 to 18.15]; summary, 16.09 [13.57 to 18.62]; P < .001 each). At retention. however, only CBVI and summary feedback groups retained superior suturing and knot-tying performance versus control (control, 8.13 [6.94 to 9.85]; CBVI, 11.92 [10.19 to 14.99] P = .037; concurrent, 9.80 [8.55 to 13.45] P = .635; summary, 111.19 [10.27 to 14.29] P = .037). Hand motion data displayed a similar pattern of results. There were no group differences in the rate of learning (P > .05). CONCLUSION: Our study showed that CBVI can be as effective as summary expert feedback in the instruction of basic technical skills to medical students. Thoughtfully incorporated into technical curricula, CBVI can make efficient use of faculty time and serve as a useful pedagogic adjunct for basic skills training. Additionally, our study provides evidence supporting an increased role of summary feedback to effectively train novices in technical skills.     

Randomized controlled trial of virtual reality simulator training: transfer to live patients

BACKGROUND: New Residency Review Committee requirements in general surgery require 50 colonoscopies. Simulators have been widely suggested to help prepare residents for live clinical experience. We assessed a computer-based colonoscopy simulator for effective transfer of skills to live patients. METHODS: A randomized controlled trial included general surgery and internal medicine residents with limited endoscopic experience. Following a pretest, the treatment group (n = 12) practiced on the simulator, while controls (n = 12) received no additional training. Both groups then performed a colonoscopy on a live patient. Technical ability was evaluated by expert endoscopists using previously validated assessment instruments. RESULTS: In the live patient setting, the treatment group scored significantly higher global ratings than controls (t(22) = 1.84, P = .04). Only 2 of the 8 computer-based performance metrics correlated significantly with previously validated global ratings of performance. CONCLUSIONS: Residents trained on a colonoscopy simulator prior to their first patient-based colonoscopy performed significantly better in the clinical setting than controls, demonstrating skill transfer to live patients. The simulator's performance metrics showed limited concurrent validity, suggesting the need for further refinement.     

Plasma lipoproteins in visceral leishmaniasis and their effect on Leishmania‐infected macrophages

This work aimed at investigating the lipid profile of zoonotic visceral leishmaniasis (VL) patients’ sera and the effect of lipoproteins on the in vitro production of tumour necrosis factor‐α (TNF‐α), interleukin (IL)‐6, IL‐10 and IL‐12 by Leishmania infantum‐infected and uninfected macrophages. Lipids were quantified in 26 VL patients’ sera and 26 healthy controls from a VL endemic area. The patients’ sera had higher triglyceride and very low density lipoprotein (VLDL) levels, and much lower apolipoprotein A1, total cholesterol, low density lipoprotein (LDL) and high density lipoprotein (HDL) levels than the control sera. Lipoprotein fractions were obtained by ultracentrifugation of sera. The addition of LDL and HDL to Leishmania‐infected and uninfected macrophages, in physiological concentrations, enhanced the production of IL‐6 and IL‐10, but not of IL‐12. LDL stimulated the production of TNF‐α only in infected macrophages, whereas HDL stimulated the production of lower amounts of TNF‐α in both infected and uninfected macrophages. VLDL stimulated only the production of IL‐10. It is proposed herein that LDL may influence the development of VL by promoting the production of TNF‐α by infected macrophages. A decrease in plasma LDL in some VL patients (to 20 mg/mL or less); however, would tend to reduce the production of TNF‐α and therefore to limit the development of immune‐mediated pathology, not withstanding the fact that it would perhaps increase the permissiveness of macrophages to Leishmania growth.     

Saliva--a pivotal player in the pathogenesis of oropharyngeal cancer

Oropharyngeal (OP) cancer, which is usually squamous cell carcinoma, is the most common head and neck malignancy and accounts for 2-4% of all new cancers. It is primarily induced by exposure to tobacco. The paradigm of cigarette smoke (CS)-induced OP cancer's pathogenesis is based on the assumption that a constant direct attack of various CS carcinogens causes widespread accumulating cellular and DNA aberrations in the OP mucosal cells, in turn eventually resulting in malignant transformation. However, there is never a direct contact between CS and the OP mucosa. Saliva, bathing the mucosa from the oral cavity to the larynx, always intervenes, and CS must first interact with saliva before it reaches the mucosa. The current study investigated the role of saliva in the pathogenesis of OP cancer. A synergistic effect of CS and saliva on oral cancer cells was demonstrated. This synergism is based on the reaction between redox active metals in saliva and low reactive free radicals in CS, which results in the production of highly active hydroxyl free radicals. Thus, when exposed to CS, salivary behavior is reversed and the saliva loses its antioxidant capacity and becomes a potent pro-oxidant milieu. The devastating role of CS-borne aldehydes was demonstrated as well. Based on these results and on our recent reports demonstrating that CS destroys various salivary components, including protective ones such as peroxidase, the most important salivary antioxidant enzyme, a comprehensive view of the pivotal role of saliva in the pathogenesis of CS-induced OP cancer is suggested.     

Interpretation of three-dimensional structure from two-dimensional endovascular images: implications for educators in vascular surgery

PURPOSE: Endovascular therapy has had a major effect on vascular surgery; surgeons perform tasks in three dimensions (3D) while viewing two-dimensional (2D) displays. This fundamental change in how surgeons perform operations has educational implications related to learning curves and patient safety. We studied the effects of experience, training, and visual-spatial ability on 3D perception of 2D angiographic images of abdominal aortic aneurysms (AAA). METHODS: A novel computer-based method was developed to produce 3D depth maps based on subjects' interpretations of 2D images. Seven experts (certified vascular surgeons) and 20 novices (medical or surgical trainees) were presented with a 2D AAA angiographic image. With software specifically designed for this study, a depth map representing each subject's 3D interpretation of the 2D angiogram was produced. The novices were then randomized into a control group and a treatment group, who received a 5-minute AAA anatomy educational session. All subjects repeated the exercise on a second AAA image. Finally, all novices were given tests of visual-spatial ability, including the Surface Development Test and the Mental Rotations Test. Comparisons between experts and novices were made with depth map comparison, a subject's perception of overall object contour. RESULTS: The depth maps were significantly different (depth map comparison, P <.001) between the expert and both novice groups for the first image. After the educational intervention, the control group and the treatment group exhibited significantly different depth maps (depth map comparison, P <.001), with treatment group depth maps more similar to those of the expert group. There were no significant correlations between the visual-spatial tests and the novice depth map comparison with the expert group. CONCLUSIONS: This is the first study to examine perception of endovascular images in an educational context. Perception of overall surface contour of 3D structures from 2D angiographic images is affected by experience and training. With application of methods of vision science to an important problem in surgery, this research represents a first step in understanding the nature of visual perceptual processes involved in execution of an increasingly common clinical task. These results have implications for understanding and studying the endovascular learning curve. CLINICAL RELEVANCE: This research represents a unique collaboration in an effort to understand and solve one of the greatest problems facing surgical educators and surgeons. This research uses applied tools in vision science to understand the perceptual constraints involved in minimally invasive surgery. Specifically, we examined the mental three-dimensional maps experts use when viewing two-dimensional displays. Furthermore, we compared experts with novices in an effort to assist surgical trainees.