Risk of bias reporting in Cochrane systematic reviews

Risk of bias is an inherent quality of primary research and therefore of systematic reviews. This column addresses the Cochrane Collaboration's approach to assessing, risks of bias, the meaning of each, indicators of low, high and uncertain, and ways that risk of bias can be represented in a Cochrane systematic review report. The sources of risk of bias that reviewers evaluate include selection, performance, detection, attrition and reporting bias. Each poses threat to the internal validity of the primary studies and requires the reviewer to judge the level of risk as high, low or unclear. Reviewers need to address how studies of higher risk of bias might impact the pooled effect.     

体外循环下治疗布-加综合征合并下腔静脉血栓形成(附49例病例报告)

目的总结在体外循环辅助下,经右房切口治疗合并下腔静脉血栓形成的布-加氏综合征的治疗经验。方法回顾我院自2002年9月至2010年7月共计49例在体外循环辅助下,经右心房切口治疗合并下腔静脉血栓的布加氏综合征的临床病例和随访资料。结果全组病人均成功的在体外循环辅助下完成经右房切口下腔静脉狭窄段扩张及血栓取出术。术中在手指破膜后再使用3.0×4.0cm球囊进行扩张。围手术期病人无死亡,无急性肺栓塞等严重并发症的发生。术后随访0～36个月,所有病人术后症状明显缓解,腹水及下肢水肿减轻至消失。1例病人术后1年后出现再狭窄,经股静脉行下腔静脉球囊扩张后好转。全组病人术后随访未见有血栓形成。结论在体外循环下,经右房切口对于合并下腔静脉血栓的布-加氏综合征是一种安全有效的治疗方法。     

Enhancement of erythrocyte superoxide dismutase activity: effects on cellular oxidant defense

To delineate further the role of superoxide dismutase (SOD) in red blood cell (RBC) oxidant defense, normal human erythrocytes were osmotically lysed and resealed in the presence of varying concentrations of exogenous SOD. This resulted in a dose-dependent increase in SOD activity in the resealed erythrocytes while maintaining nearly normal RBC hemoglobin concentration (less than 10% decrease from the control value), cell volume, and cellular deformability. Surprisingly, a five- or ninefold increase in SOD activity yielded no additional protection against superoxide-generating drugs (phenazine methosulfate or menadione sodium bisulfite). No significant differences were observed between the control and SOD-loaded RBCs in O2-driven methemoglobin formation or generation of thiobarbituric acid-reactive substances. In contrast, RBCs with elevated SOD activity pretreated with sodium azide (to block catalase activity) or 1-chloro-2,4- dinitrobenzene (to deplete reduced glutathione, GSH) showed significantly enhanced methemoglobin generation in response to superoxide generating drugs. No differential response was noted between the control, control-resealed, and SOD-loaded RBCs to oxidants other than superoxide. Based on our results and other data, we conclude that elevated SOD activity may imbalance cellular oxidant defense, resulting in enhanced oxidation due to the accelerated generation of H2O2, the product of O2- dismutation. This effect is significantly exacerbated under conditions in which H2O2 catabolism is altered.     

Determinants of Female and Male Condom Use Among Immigrant Women of Central American Descent

This study was designed to determine factors that influence female and male condom use among Central American women, applying the theory of planned behavior. A cross-sectional design was employed and a sample of 175 Central American women, 18–50 years old, was recruited from a community-based clinic in Los Angeles County. Participants in this study were interviewed face-to-face. Attitude, subjective norm, and perceived behavioral control explained 41% and 45% of the variation in the intention to use male and female condoms, respectively. Respondents' friends and mothers influenced their subjective norms. Beliefs regarding sexual sensation and sexually transmitted infection/pregnancy prevention affected respondents' attitudes toward condoms. Trust issues were also a major factor affecting attitudes toward female condoms. Condom use and sex negotiation skills predicted control over condoms. Results of this study can be used to design HIV/AIDS prevention programs that help women feel control over condom use and their sexual behavior.     

Cross-sectional study of bone density in asthmatic children

The emphasis in treatment of asthma in children has shifted from bronchodilators to inhaled anti-inflammatory medications, including inhaled corticosteroids (ICS). Children with chronic asthma and moderate to severe symptoms have been targeted as particularly deserving of maintenance therapy with ICS. We have previously reported a cross-sectional study of bone density in children treated with ICS. There was no significant difference between the total bone density of asthmatic patients and controls. We sought to extend the information available on bone density in asthmatic children by evaluating 15 asthmatic subjects taking daily ICS (beclo-methasone dipropionate) and comparing them with age- and sex-matched controls. We compared total and regional bone density, bone age, and calcium intakes in these subjects. Asthmatic subjects were on ICS for 4–60 months, with doses ranging from 200 to 450 μg/day. There was no significant difference between asthmatics and matched controls for height, weight, % RDA Ca²⁺, or bone age. The asthmatic subjects had bone density (total and regional measurements) equivalent to their controls. These results provide additional support for the safety of low-dose ICS on bone density in asthmatic children. Pediatr Pulmonol. 1995; 20:189–192 . © 1995 Wiley-Liss, Inc.     

A higher cellular sodium turnover rate in cultured skin fibroblasts from blacks

Differences in cellular Na+ and K+ regulation may relate to the pathogenesis of essential hypertension and the predisposition of blacks to this disease. To explore these tenets, we examined several aspects of cellular Na+ homeostasis in serially passed, cultured skin fibroblasts from 30 subjects (15 hypertensive blacks and whites and normotensive subjects matched for sex, age, and race.) Fibroblasts from blacks demonstrated higher cellular Na+ turnover rates than did those from whites. This difference was expressed by accelerated Na+-K+ pump activity (ouabain-sensitive Na+ washout rate, 3.46 +/- 0.216 for blacks vs 1.84 +/- 0.283 mEq/L/min for whites; p = 0.0006) and a higher rate of cellular accumulation of Na+ in the presence of ouabain (0.964 +/- 0.0743 vs 0.562 +/- 0.0440 mEq/L/min for blacks and whites, respectively; p = 0.0045). Associated with these findings, fibroblasts from blacks had higher cellular Na+ concentration than did those from whites (9.78 +/- 0.512 vs 7.50 +/- 0.400 mEq/L; p = 0.0170, as measured by atomic absorption, and 7.84 +/- 0.470 vs 5.03 +/- 0.980 mEq/L; p = 0.0141, as derived from the equilibrium distribution ratio of 22Na+). It is concluded that blacks differ from whites with respect to cellular Na+ turnover rate, which is evidenced by an increased Na+ influx and accelerated Na+-K+ pump activity in their fibroblasts. Our findings support the tenet that innate racial differences in cellular Na+ regulation may underlie the predisposition of blacks to hypertension.     

Estimation of bone mineral density in children with juvenile rheumatoid arthritis

Bone mineral content of different areas of the skeleton was measured by dual photon absorptiometry in 20 children with juvenile rheumatoid arthritis (JRA) and compared to 20 age and sex matched healthy children. Spinal density was similar in both groups in prepubertal children but decreased in the postpubertal girls with JRA. Total bone density was also decreased in the postpubertal girls. Six children with JRA had repeat scans 12 to 24 months later; in 3 children total bone mineral content increased significantly with an intensive management program. Our study suggests that bone mineral density does not show a pubertal increase in children with JRA, as it does in healthy children.