Sonic hedgehog guides commissural axons along the longitudinal axis of the spinal cord

Dorsal commissural axons in the developing spinal cord cross the floor plate, then turn rostrally and grow along the longitudinal axis, close to the floor plate. We used a subtractive hybridization approach to identify guidance cues responsible for the rostral turn in chicken embryos. One of the candidates was the morphogen Sonic hedgehog (Shh). Silencing of the gene SHH (which encodes Shh) by in ovo RNAi during commissural axon navigation demonstrated a repulsive role in post-commissural axon guidance. This effect of Shh was not mediated by Patched (Ptc) and Smoothened (Smo), the receptors that mediate effects of Shh in morphogenesis and commissural axon growth toward the floor plate. Rather, functional in vivo studies showed that the repulsive effect of Shh on postcommissural axons was mediated by Hedgehog interacting protein (Hip).     

个体化下肢小腿假肢接受腔设计的生物力学评价技术研究

作为传递体重、固定假肢的部件 ,接受腔对于小腿假肢使用的舒适性和方便程度有决定性的作用。本研究建立了基于有限元应力分析的小腿假肢生物力学评价技术平台 ,实现了小腿残端 /接受腔 3D几何建模与信息交互、三维有限元自动建模及应力分析。 3D模型与信息交互的实现基于得到广泛支持的OpenGL技术 ,有限元模型的构建采用了专门针对小腿残端 /接受腔结构特点的自动建模方法 ,通过构建档案数据库系统作为整个系统的操作平台。该技术平台可与现有的CAD/CAM系统相结合 ,为接受腔的个体化设计提供生物力学定量化依据。其临床应用将改善传统的设计流程 ,提高设计效率。同时 ,它也是未来构建接受腔设计专家 /智能系统的基础。     

碱离子水饮用后血小板聚集率的的变化(附30例报告)

目的:报告30例饮用豪斯牌碱离子水前、后血小板聚集率的变化。方法:饮用碱离子水前、后(2～3月,>3～6月)作比浊法血小板聚集试验,以1分钟、5分钟及5分钟内最大聚集率(Max％)为指标,同时检测部分血粘度指标及凝血因子,并用自动生化仪检测血糖、血脂、主要电解质及部分肝、肾功能。结果:饮碱离子水后,血小板聚集率明显下降,而以疾病组(Max>80％)下降尤为明显,P均<0.001。饮碱离子水后血小板聚集率的下降,部分可能与损伤的血管内皮得到修复有关。主要电解质及部分肝、肾功能无明显异常改变。结论:由于心、脑血管血栓性疾病患者血小板聚集率多明显升高,饮碱离子水后血小板聚集率明显下降,且长期饮用对主要电解质及部分肝、肾功能无明显异常改变,作者认为碱离子水使用方例、安全、有效、价廉,因而对心、脑血管血栓性疾病防治方面可能是一种积极的辅助方法,值得临床进一步探索。     

A Clinical and Histologic Comparison of Percutaneous Dilational Versus Conventional Surgical Tracheostomy

To directly compare percutaneous dilational tracheostomy (PDT) with conventional surgical tracheostomy, a prospective study was performed in 83 patients requiring tracheostomy for prolonged mechanical ventilation in the intensive care unit or after surgery for a large tumor in the upper respirodigestive tract. Median follow-up was 355 days after PDT and 338 days after conventional tracheostomy. The overall morbidity rate was significantly lower with PDT than with conventional tracheostomy (6.4% vs 36.1%; P < 0.001). Compared with conventional tracheostomy, PDT was also associated with a significantly lower incidence of postoperative bleeding (2.1% vs 13.9%; P < 0.05) and postoperative wound infection (0% vs 22.2%; P < 0.001). There were no clinical signs of laryngotracheal stenosis in either group. In conclusion, PDT is a simple, fast, safe bedside procedure that is associated with significantly lower morbidity than standard surgical tracheostomy.     

Significance of incidental 18F-FDG accumulations in the gastrointestinal tract in PET/CT: correlation with endoscopic and histopathologic results.

This study was undertaken to identify the clinical value of incidentally detected lesions (IDLs) in the gastrointestinal tract (GIT) with (18)F-FDG PET/CT. METHODS: The reported database of 3,281 patients who underwent partial-body (18)F-FDG PET/CT scans from April 2001 to September 2003 was reviewed. Patients with incidental (18)F-FDG accumulations in the GIT that were associated with concomitant abnormal soft-tissue density or wall thickening on the native CT were evaluated. Incidental PET/CT findings were correlated with endoscopic and histopathologic results. RESULTS: According to our selection criteria, 98 (3%) of the 3,281 patients had an IDL of the GIT on (18)F-FDG PET/CT. Correlative endoscopic findings were available in 69 (70%) of 98 patients. Of these, 13 patients (19%) were harboring newly occurring cancers of the GIT in addition to preexisting aerodigestive tract tumors (n = 12) and malignant melanoma (n = 1). Twenty-nine (42%) patients were identified with precancerous lesions, such as advanced colonic adenomas (n = 27), Barrett's esophagus (n = 1), and intestinal metaplasia of the gastric mucosa (n = 1). Inflammatory and other benign GIT lesions were detected in 12 (17%) and 6 (8%) patients, respectively. In 9 (13%) patients, PET/CT was false-positive, showing normal findings in subsequent endoscopic examinations. In 20 (28%) of 69 patients, PET/CT findings had a relevant impact on the clinical management. Twenty-nine (30%) of the 98 patients were not subject to a further endoscopic examination because of the extent and nature of the primary tumor (n = 17), loss to follow-up (n = 7), death shortly after PET (n = 3), and patient unwillingness (n = 2). CONCLUSION: Although IDLs of the GIT on (18)F-FDG PET/CT scans are found only in about 3% of cases, they are associated with a substantial risk of an underlying cancerous or precancerous lesion. Early identification of these occult lesions may have a major impact on the patients' management and outcome.     

The management of acute abdominal pain in children

Objective : Acute abdominal pain is a common problem in childhood, and appendicitis is frequently diagnosed by general practitioners and doctors working in emergency departments. The objective of the present report was to determine the frequency of appendicitis in a group of children with acute abdominal pain presenting to the emergency department of a general hospital, as well as attempting to analyse the manner in which these patients were managed.
Methodology : The initial assessment in hospital (by resident hospital staff) of the study group of patients was analysed and their subsequent clinical progress documented.
Results : The present report shows that the vast majority of children with acute abdominal pain do not have appendicitis and that appendicitis is significantly over-diagnosed by junior hospital doctors.
Conclusions : Appendicitis is a clinical diagnosis, best made by an experienced member of the paediatric surgical team. Frequent review, with a minimum of investigations, provides the best means of making a rational decision regarding surgery.     

Percutaneous tracheostomy: a comprehensive evaluation

Percutaneous tracheostomy (PT) is an ancient procedure that has recently attracted increasing interest. While there are numerous publications in the literature, there remains confusion due to the large variety of techniques and instruments with which it has been performed and the wide disparity in clinical outcome. This study evaluates the international literature on over 1,500 cases, classifies the techniques that have been used, analyzes the safety of each method, and reports a prospective outcome and cost analysis of 130 cases undergoing what we determined to be the safest method. We found that PT performed with the correct instruments and technique under bronchoscopic surveillance has a lower incidence of complications than open tracheostomy (OT). Cost estimation demonstrated that PT may be significantly more expensive than bedside OT. While we recommend PT as a relatively safe and expedient method of tracheostomy for selected intubated patients in an intensive care unit, it does not offer an advantage for patients who must be taken to the operating room, and should not deprive house officers of necessary experience in OT in this setting.