中频交变磁场照射后小鼠的行为学变化

目的:目前电磁辐射对生物体行为学方面的研究还很薄弱,设立不同磁场的强度和不同照射的周期,观察中频领域磁场照射对小鼠的自主活动和学习记忆的影响。方法:实验于2007-05-10/06-15在清华大学医学院和中国医学科学院药用植物研究所完成。①实验材料:磁场发生装置:中频交变磁场发生装置由清华大学工程物理系医学物理与工程研究所自主研发,可产生频率为40kHz,场强为28.8A/m,28.8kA/m的中频交变磁场。自主活动测试箱:中国医学科学院药用植物研究所提供,为一可封闭的金属箱,内置摄像头。4只黑色塑料测试桶分别置于箱子四角。水迷宫测试箱:中国医学科学院药用植物研究所提供。②实验动物及方法:将80只小鼠随机分为不同场强照射组和对照组。强磁场照射1组:11.6kA/m/40kHz,1h/d,连续照射7d。强磁场照射2组:11.6kA/m/40kHz,2h/d,连续照射7d。强磁场照射3组:11.6kA/m/40kHz,2h/d连续照射15d。弱磁场照射组:28.8kA/m/40kHz,2h/d,连续照射7d。对照组除了未放入磁场照射,其他条件与照射组一致。实验过程中对动物处置符合动物伦理学要求。③实验评估:观察其一般活动的改变,并采用自主活动测试箱和水迷宫测试箱进行测试,观察各组小鼠的自主活动和学习记忆的改变。结果:①一般行为观察:与对照组小鼠对比,经过中频交变磁场照射过的各组小鼠活跃度减低,毛色较差。强磁场照射3组(145G,2h/d,连续15d)于第11天和13天分别死亡1只。②自主活动检测结果:强磁场照射2,3组小鼠的运动路程、运动速度、运动时间明显低于对照组(P<0.05)。③水迷宫测试结果:在学习记忆检测阶段撤掉平台,发现各组动物2min内穿越平台原来所在象限的次数没有明显差别(P>0.05)。结论:中频交变磁场照射会给小鼠的自发活动造成一定影响,对学习记忆没有影响。     

The use of "war games" to enhance high-risk clinical decision-making in students and residents

BACKGROUND: Initial studies found that residents and students performed poorly in simple clinical scenarios. We hypothesized that repeated simulations in the "war games" format would improve performance. METHODS: Participants included medical students and residents on the trauma and surgical intensive care unit (SICU) services. Subjects were given a nursing report of an unstable patient and asked to verbalize management of the situation. Responses were transcribed and graded. RESULTS: Eighty subjects and 5 experts participated in 227 simulations. Naive medical students, postgraduate year (PGY)-1, and PGY-2+ subjects performed worse than experts (P <.05). After participation in >/=3 war games sessions, trainees' scores were similar to experts. Subjects with the least amount of clinical experience demonstrated the most improvement. DISCUSSION: We have designed an educational system that rapidly enhances the cognitive performance of students and residents. This may represent an important tool in assessing and enhancing the competencies of medical trainees in a safe environment.     

Anterior compartment pressure measurement in closed fractures of leg

Background:

Compartment syndrome is a potentially devastating condition. Increased intracompartmental pressure has been incriminated as the primary pathogenic factor in compartment syndrome. The purpose of this prospective study was to monitor the anterior compartmental pressure and differential pressure to minimize the incidence of acute compartment syndrome.

Materials and Methods:

Seventy-five consecutive cases of closed fractures of leg presenting within six hours of injury were taken for measurement of anterior compartment pressure at the level of fracture and at 5 cm and 10 cm away from the fracture site, using the Whitesides'' infusion technique. A differential pressure of less than 30 mm Hg was taken as the criterion for diagnosis of compartment syndrome.

Results:

Two patients (2.67%) developed acute compartment syndrome. The mean anterior compartment pressures were highest at the level of the fracture and went on decreasing as we went away from the fracture site, which was found to be statistically significant (P < 0.001).

Conclusion:

Compartment pressure measurement is the most reliable and objective method for early diagnosis of compartment syndrome. Whitesides'' infusion technique is a relatively easy and inexpensive method to come to a diagnosis of compartment syndrome in a developing country like India. Differential pressure is more reliable than absolute pressure in predicting the development of an impending compartment syndrome.     

Sphingosine-1-phosphate induces an antiinflammatory phenotype in macrophages

Activated macrophages acquire a proinflammatory (classic) or antiinflammatory (alternative) phenotype that influences atherosclerosis. The present study investigated whether sphingosine-1-phosphate (S1P), with its known antiinflammatory effects, could regulate the inflammatory phenotype of lipopolysaccharide (LPS)-stimulated mouse macrophages. Activation of macrophages by LPS significantly increases proinflammatory cytokine secretion. Pretreatment of macrophages with 500 nmol/L S1P markedly reduced LPS-mediated secretion of tumor necrosis factor-alpha, monocyte chemoattractant protein-1, and interleukin-12. Such antiinflammatory actions were also evident in LPS-stimulated macrophages treated with the S1P1 receptor-specific agonist SEW2871. Pharmacological antagonism of the S1P1 receptor on macrophages using the S1P1-specific antagonist VPC44116 also blocked proinflammatory cytokine secretion in response to LPS. Studies using bone marrow-derived macrophages from S1P2-deficient mice revealed that the S1P2 receptor did not play a pivotal role in this process. Thus, activation of the S1P1 receptor in mouse macrophages limits the expression of proinflammatory cytokines. Furthermore, we demonstrated that S1P increased arginase I activity and inhibited LPS-induced inducible NO synthase activity in LPS-treated macrophages, again through S1P1 receptor activation on macrophages. Analysis of a 1.7-kb region of the murine inducible NO synthase promoter revealed the presence of putative nuclear factor kappaB, activator protein-1, and STAT-1 response elements. Using inducible NO synthase promoter-reporter constructs, we found that S1P significantly reduced the nuclear factor kappaB-mediated induction of inducible NO synthase. These findings demonstrate an important role for S1P in the regulation of macrophage phenotypic switching. Therefore, we conclude that S1P promotes the production of an alternative antiinflammatory macrophage phenotype through activation of the macrophage S1P1 receptor.     

Abnormalities of Intestinal Rotation in Patients with Congenital Heart Disease and the Heterotaxy Syndrome

Objective. Abnormalities of intestinal rotation (AIR) are seen in association with congenital heart disease and heterotaxy syndrome. The prevalence of these abnormalities and recommendations for management are unclear. Our objective was to determine the prevalence of screening for AIR by elective imaging among our group and prophylactic vs. emergent surgical intervention for AIR in patients with congenital heart disease and heterotaxy syndrome. Methods. From October 1988 through October 2000, we identified 74 patients with congenital heart disease and heterotaxy syndrome, 44 (59%) asplenia, 30 (41%) polysplenia. Abdominal imaging was performed in 34 patients (45%). Twenty-four (32%) were found to have AIR. Of 34 patients imaged, 22 (65%) were found to have AIR. Two patients not imaged were found to have AIR: one at autopsy, and the other, incidentally during other abdominal surgery. Because imaging was performed based on individual cardiologist’s practice style that did not change over the period of the study and rarely secondary to symptoms, it is likely that the prevalence of AIR in the patients that were not electively imaged would be similar. Results. There was no statistical difference in the presence of AIR between asplenic (34%[15/44]) and polysplenic (30%[9/30]) patients. Of the 22 patients imaged with AIR, 18 underwent Ladd procedure. Five of 12 imaged patients without AIR were found to have other significant gastrointestinal pathologies requiring intervention including gastrostomy tube placement for reflux (3), duodenal web (1), and biliary atresia (1). Of the 40 patients who were not pre-emptively imaged, none suffered acute obstruction solely secondary to AIR. However, in 2 patients intestinal obstruction was suspected and subsequently discovered by imaging and/or laparotomy due to other intestinal anomalies. Conclusions. AIR is common among patients with heterotaxy syndrome and congenital heart disease. We recommend that patients with congenital heart disease and heterotaxy syndrome have routine elective abdominal imaging of their gastrointestinal tract at birth as part of their evaluation.     

Association of body weight with condition-specific quality of life in male veterans

PURPOSE: We hypothesized that obese adults with coronary heart disease, obstructive lung disease, or depression would report greater impairments in health-related quality of life owing to their angina, dyspnea, or depressive symptoms as compared with persons with normal body weight. METHODS: We analyzed cross-sectional data from the Ambulatory Care Quality Improvement Project, a multicenter study of veterans enrolled in general internal medicine clinics. Health-related quality of life was assessed using the Medical Outcomes Study Short Form-36, the Seattle Angina Questionnaire, the Seattle Obstructive Lung Disease Questionnaire, and the Hopkins Symptom Checklist for Depression. RESULTS: Compared with patients of normal weight (body mass index: 18.5 to 24.9 kg/m2), underweight patients (body mass index <18.5 kg/m2) reported health-related quality-of-life scores that were at least 5% lower (worse) in all 15 quality-of-life domains examined. Patients with class III obesity (body mass index > or =40 kg/m2) reported quality-of-life scores that were at least 5% lower than those of normal weight patients in eight domains. Scores of overweight patients (body mass index: 25 to 29.9 kg/m2) were higher (better) than those of normal weight patients in 11 domains. CONCLUSION: Body mass index was strongly associated with generic- and condition-specific health-related quality of life. Our results suggest that, when considering health-related quality-of-life outcomes among veterans, the optimal body mass index may be above the "normal" range. Further research should test the validity of the 1998 National Institutes of Health body mass index categories as predictors of health outcomes among veterans.     

In vitro characterization of the human recombinant soluble granulocyte- macrophage colony-stimulating factor receptor

We have cloned, expressed, and partially purified a naturally occurring, truncated, soluble form of the human granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor alpha subunit to investigate its biochemical and biologic properties. The soluble receptor species lacks the transmembrane and cytoplasmic domains that are presumably removed from the intact receptor cDNA by a mechanism of alternative splicing. The resulting soluble 55- to 60-kD glycosylated receptor species binds GM-CSF with a dissociation constant (kd) of 3.8 nmol/L. The soluble GM-CSF receptor successfully competes for GM-CSF binding not only with the transmembrane-anchored GM-CSF receptor alpha subunit but also with the native oligomeric high-affinity receptor complex. In addition, in human bone marrow colony-forming assays, the soluble GM-CSF receptor species can antagonize the activity of GM-CSF. Our data suggest that the soluble GM-CSF receptor may be capable of acting in vivo as a modulator of the biologic activity of GM-CSF.