Radiology residents’ skill level in chest x-ray reading

Rationale and objectives

To evaluate the mean skill level of radiology residents in chest X-ray (CXR) reading, with regard to cognitive mechanisms involved in this task and to investigate for potential factors influencing residents’ skill.

骨髓基质细胞条件培养液通过p38信号转导通路诱导中脑神经干细胞分化

目的：骨髓基质细胞条件培养液能够诱导中脑神经干细胞分化为高比例神经元，但具体机制尚不十分清楚。选择p38信号转导通路作为观察切入点，剖析其在诱导分化途径中所扮演的角色。方法：实验于2006—04／2007—03在河北省脑老化与认知神经科学实验室完成。①实验方法：将SD大鼠麻醉后处死，分离股骨和胫骨，冲洗骨髓腔，将洗出的细胞悬液离心，悬浮后接种，培养48h后弃去未贴壁细胞，更换新的培养基，6d左右可进行传代，约铺满85％瓶底后弃去培养液，更换为含2％B27的Neurobasal培养液，24h后经过离心的上清液即为骨髓基质细胞条件培养液。取新生SD大鼠中脑，机械分散成单细胞后离心弃上清，加入培养液分散过滤，接种时加入含2％B27的DMEM／F12培养基和20μg／L碱性成纤维细胞生长因子，7d左右的单个神经干细胞便可增殖形成球体。将第2-3代神经干细胞球种植于预先包被多聚赖氨酸的培养皿中，贴壁后更换培养液。设立对照组和抑制剂组，均加入骨髓基质细胞条件培养液，此外抑制剂组还加入p38信号转导通路抑制剂SB203580至终浓度4μmol／L。②实验评估：第7天进行免疫细胞化学染色，检测表达微管相关蛋白2的神经元与表达胶质原纤维酸性蛋白的星形胶质细胞在分化细胞中所占的比例。结果：①神经干细胞分化过程中的形态学变化及p38信号转导通路抑制剂的影响：加入抑制剂后24h，光镜下可见神经干细胞长出的细胞有两种类型：一类细胞体积较小，边缘整齐，立体感强，周围有光晕并在两极有突起，免疫荧光染色显示这类细胞微管相关蛋白2呈阳性表达，即为神经元；另一类细胞突起较粗大，不规则，多聚集在神经干细胞球的中央，呈放射状排列，免疫荧光染色表明这类细胞为胶质原纤维酸性蛋白阳性的星形胶质细胞。②神经元及星形胶质细胞在分化细胞中所占的比例：p38信号转导通路抑制剂作用于神经干细胞7d时，从神经干细胞分化成神经元的比例明显低于对照组（P〈0．01），分化成星形胶质细胞的比例明显高于对照组（P〈0．05）。结论：骨髓基质细胞条件培养液在促进神经干细胞分化为神经元的同时，能够抑制其分化为星形胶质细胞，提示骨髓基质细胞分泌的可溶性分子可能是通过p38信号转导通路起作用的。     

Long Working Hours and Risk of Recurrent Coronary Events

BackgroundEvidence from prospective studies has suggested that long working hours are associated with incident coronary heart disease (CHD) events. However, no previous study has examined whether long working hours are associated with an increased risk of recurrent CHD events among patients returning to work after a first myocardial infarction (MI).ObjectivesThe purpose of this study was to examine the effect of long working hours on the risk of recurrent CHD events.MethodsThis is a prospective cohort study of 967 men and women age 35 to 59 years who returned to work after a first MI. Patients were recruited from 30 hospitals across the province of Quebec, Canada. The mean follow-up duration was 5.9 years. Long working hours were assessed on average 6 weeks after their return to work. Incident CHD events (fatal or nonfatal MI and unstable angina) occurring during follow-up were determined using patients’ medical files. Hazard ratios were estimated using Cox proportional hazard regression models. Splines and fractional polynomial regressions were used for flexible exposure and time modeling.ResultsRecurrent CHD events occurred among 205 patients. Participants working long hours (≥55 h/week) had a higher risk of recurrent CHD events after controlling for sociodemographics, lifestyle-related risk factors, clinical risk factors, work environment factors, and personality factors (hazard ratio vs. 35 to 40 h/week: 1.67; 95% confidence interval: 1.10 to 2.53). These results showed a linear risk increase after 40 h/week and a stronger effect after the first 4 years of follow-up and when long working hours are combined with job strain.ConclusionsAmong patients returning to work after a first MI, longer working hours per week is associated with an increased risk of recurrent CHD events. Secondary prevention interventions aiming to reduce the number of working hours among these patients may lower the risk of CHD recurrence.     

Brucella bacteraemia: clinical and laboratory observations in 160 patients

OBJECTIVES: To describe the clinical, serological, and prognostic features of bacteraemic brucellosis in an endemic region. METHODS: Retrospective case series of 160 patients admitted from 1983 to 1995 to a hospital providing secondary and tertiary level medical care in Saudi Arabia. All patients had positive blood cultures for Brucella species, predominantly Brucella melitensis. RESULTS: Bacteraemia was documented in 38% of 545 cases of brucellosis admitted to our institution during the study period. The main clinical syndromes were febrile illness alone (44%) or fever with arthritis (42%). Of 68 isolates that were speciated, 93% were Brucella melitensis. Initial agglutinating antibody titre was > or =1:320 in 96% of the patients. Antimicrobial resistance of B.melitensis isolates was: co-trimoxazole, 29%; rifampicin, 3.5%; streptomycin, 0.6%; and tetracycline, 0.6%. No increase in resistance was noted over the 13-year study period. Commonly used antimicrobial regimens consisted of streptomycin plus tetracycline or rifampicin plus doxycycline given for 6 weeks. Seven patients (5%) had relapse of their symptoms after antimicrobial therapy. Three of these had infective endocarditis with repeated bacteraemia. These patients required aortic valve replacement and recovered after surgery. The remaining four patients responded to a second course of therapy. CONCLUSIONS: Brucella bacteraemia is an acute febrile disease often associated with rheumatologic complaints. Most patients have an agglutinating antibody titre > or =1:320 and respond well to standard chemotherapy regimens with low mortality.     

Incidence and Survival of Mucinous Adenocarcinoma of the Colorectum: A Population-Based Study From an Asian Country

PURPOSE: Previous studies have shown conflicting results on the prognosis of mucinous adenocarcinoma of the colorectum. This could be because of heavy bias on patient selection. Furthermore, little data are available from Asian populations. This study was designed to examine incident and prognostic characteristics of mucinous adenocarcinoma of the colorectum based on data obtained from a population-based, Asian, cancer registry. METHODS: A total of 627 of 15,762 were mucinous adenocarcinoma cases from invasive colorectal cancer patients registered in the Singapore Registry from 1968 to 1997. Age-standardized incidence rate was used to describe the incident pattern of mucinous adenocarcinoma of colon and rectum during a period of time. Survival of patients with mucinous adenocarcinoma or ordinary adenocarcinoma was compared using relative survival and proportional hazards model. RESULTS: Age-standardized incidence rate of mucinous adenocarcinoma of the colon and rectum were almost unchanged in males, rising slightly in females during the study periods from 1968 to 1972 to 1993 to 1997. The proportion of mucinous adenocarcinoma cases was similar among genders and calendar-year periods but was higher in younger age groups, Malays and Indians, in advanced stages of the disease, and proximal colon. Five-year relative survival rate of patients with mucinous adenocarcinoma were similar in the colon but were lower in the rectum. CONCLUSIONS: Colorectal mucinous adenocarcinoma as a different etiologic entity from other histologic types of colorectal cancer was suggested. Possibly greater aggressiveness of mucinous adenocarcinoma occurring in the rectum requires confirmation but suggests that mucin is important in the pathogenesis of mucinous adenocarcinoma.     

Neovascularisation and the induction of cell adhesion molecules in response to degradation products from orthopaedic implants.

OBJECTIVES--To characterise the cellular interactions and the mechanisms involved in the recruitment of inflammatory macrophages and T cells to the bone implant interface in 30 patients with aseptically loosened orthopaedic prostheses. METHODS--Cell adhesion molecules E-selectin, VCAM-1, ICAM-1 and the receptors LFA-1 and CR3 were immunolocalised on cryostat sections of the bone-implant interface obtained during revision arthroplasty. The percentage of expression on vascular endothelium was determined on serial sections. RESULTS--E-selectin was upregulated on different vessels in 21 patients. Its expression correlated strongly with the presence of metal wear debris. VCAM-1 was detected on vessels in six patients only, and was coexpressed with E-selectin in three patients with metal debris. VCAM-1 was more frequently observed in the lining cells on the implant side. ICAM-1 was upregulated on vessels on the bone side only in 13 patients, and was more strongly expressed on aggregates of macrophages and multinucleated giant cells on the implant side. These macrophage aggregates coexpressed both ICAM-1 and CR3. CONCLUSION--Our findings implicate the contribution of three different pathways in the recruitment of inflammatory cells to the joint in response to orthopaedic implant wear particles. The association of E-selectin expression and metal debris may suggest hypersensitivity reactions. Finally, the simultaneous expression of ICAM-1 and CR3 on the same macrophages on the implant side may predict an additional function of these molecules in homotypic adhesion/cell aggregation that precede differentiation of phagocytes to multinucleated giant cells.