HCY与大鼠心肌损伤相关性及其动态变化规律

目的探讨血清同型半胱氨酸(homocysteine,HCY)与大鼠心肌损伤相关性及其动态变化规律。方法将大鼠分为正常组、穿线损伤组、结扎损伤组;结扎损伤组结扎冠状动脉制作大鼠心肌梗死模型,穿线损伤组只穿线不结扎,于手术前,手术后1 h、3 h、6 h、12 h、24 h、3 d、7 d眼球后静脉丛取血,测定血清中HCY含量。结果与正常组比较,穿线损伤组、结扎损伤组血清HCY含量均在1h开始升高(P<0.05),3 h达到高峰(P<0.01),且一直持续到术后12 h(P<0.01);与穿线损伤组比较,结扎损伤组血清HCY含量在心肌损伤后1～6 h显著降低,12 h～3 d显著升高。结论轻度损伤、重度损伤均可导致血清HCY含量升高,表明其可以作为评价实验动物心肌损伤的灵敏性检测指标;损伤轻重程度与血清HCY含量升高程度没有直接相关性,不能作为判断心肌损伤程度的指标。     

A summary of important documents in the field of research ethics

Today's researchers are obligated to conduct their studies ethically. However, it often seems a daunting task to become familiar with the important ethical codes required to do so. The purpose of this article is to examine the content of those ethical documents most relevant to the biomedical researcher. Documents examined include the Nuremberg Code, the Declaration of Helsinki, Henry Beecher's landmark paper, the Belmont Report, the U.S. Common Rule, the Guideline for Good Clinical Practice, and the National Bioethics Advisory Commission's report on research protections for the mentally ill.     

Dimensional approaches to experimental psychopathology of schizophrenia: shift learning and report of psychotic-like experiences in college students

Adopting a dimensional approach to experimental psychopathology, and taking into account inconsistencies in the previous literature, we examined whether reports of psychotic-like experiences in undergraduate students were associated with shift-learning deficits, akin to those seen in schizophrenia. The participants (N=72) were tested on a new compound stimulus discrimination task before and after a target shift, and were administered a multi-dimensional schizotypy inventory (O-LIFE). Performance impairment following a target shift was associated with the negative (introvertive anhedonia) and the impulsive (impulsive non-conformity) dimension of schizotypy, but not with the positive (unusual experiences), nor the disorganised (cognitive disorganisation) dimension. None of the schizotypy measures were associated with performance on discrimination learning before the target shift. The obtained results are in line with past evidence that shift learning is associated with the severity of the negative symptomatology of schizophrenia. The possibility that psychotic-like features may contribute differentially to performance deficits across successive stages of learning is considered.     

Blood flow rate and wall shear stress in seven major cephalic arteries of humans

Blood flow rate () in relation to arterial lumen radius (r_i) is commonly modelled according to theoretical equations and paradigms, including Murray’s Law ( ∝ ) and da Vinci’s Rule ( ∝ ). Wall shear stress (τ) is independent of r_i with Murray’s Law (τ ∝ ) and decreases with da Vinci’s Rule (τ ∝ ). These paradigms are tested empirically with a meta-analysis of the relationships between and r_i in seven major arteries of the human cephalic circulation from 19 imaging studies in which both variables were presented. The analysis shows that ∝ and τ ∝ , more consistent with da Vinci’s Rule than Murray’s Law. This meta-analysis provides standard values for , r_i and τ in the human cephalic arteries that may be a useful baseline in future investigations. On average, the paired internal carotid arteries supply 75%, and the vertebral arteries supply 25%, of total brain blood flow. The internal carotid arteries contribute blood entirely to the anterior and middle cerebral arteries and also partly to the posterior cerebral arteries via the posterior communicating arteries of the circle of Willis. On average, the internal carotid arteries provide 88% of the blood flow to the cerebrum and the vertebral arteries only 12%.     

Can Emergency Department Triage Nurses Appropriately Utilize the Ottawa Knee Rules to Order Radiographs?—An Implementation Trial

OBJECTIVE: To determine whether triage nurses can successfully interpret the Ottawa Knee Rule (OKR) and order knee radiographs according to the OKR. METHODS: This was a prospective implementation trial of a clinical decision rule, set in a suburban, community emergency department (ED), evaluating a convenience sample of ED patients aged > 17 years with acute knee injuries. Patients were excluded for altered mental status, distracting injuries, and knee lacerations. Triage nurses and attending emergency physicians (EPs) were trained in appropriate use of the OKR. The triage nurses evaluated eligible patients and radiographs were ordered according to their interpretation of the OKR. EPs who were initially blinded to the triage assessments also evaluated the patients. EPs could add an x-ray order if, according to their assessment of the OKR, one was indicated and a radiograph had not been ordered by the nurse. Nurses and EPs recorded their blinded assessments on standardized data collection instruments. Kappa values were calculated to assess interobserver agreement (IOA) between nurses and EPs; sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) were calculated as appropriate. RESULTS: One hundred three patients were enrolled; 53% were female; 10 fractures were identified (9.7%). The IOAs between the nurses and EPs for each of the criteria were moderate to almost perfect: age-0.94; fibular head tenderness-0.4; isolated patellar tenderness-0.68; inability to bend knee to 90 degrees-0.73; inability to bear weight-0.76. The IOA was moderate (0.52) for the overall interpretation of the OKR by nurses and EPs. Sensitivity of nurse interpretation of the OKR for fracture was 70%, specificity 33%, NPV 91%, PPV 10%. Sensitivity of EP interpretation of the OKR for fracture was 100%, specificity 25%, NPV 100%, PPV 13%. CONCLUSIONS: Triage nurses showed fair to good ability to appropriately apply the OKR to pre-order knee radiographs.     

绒毛与胚胎核型不一致性研究

为探讨绒毛与胚胎不一致问题，对２３例孕早期产前诊断与同一胚胎的羊水、脐带血、或人工流产绒毛对照及２７份人工流产绒毛与同一胚胎组织对照，提出了绒毛产前诊断结果的处理意见     

A comparison between two neural network rule extraction techniques for the diagnosis of hepatobiliary disorders

Neural networks have been widely used as tools for prediction in medicine. We expect to see even more applications of neural networks for medical diagnosis as recently developed neural network rule extraction algorithms make it possible for the decision process of a trained network to be expressed as classification rules. These rules are more comprehensible to a human user than the classification process of the networks which involves complex nonlinear mapping of the input data. This paper reports the results from two neural network rule extraction techniques, NeuroLinear and NeuroRule applied to the diagnosis of hepatobiliary disorders. The dataset consists of nine measurements collected from patients in a Japanese hospital and these measurements have continuous values. NeuroLinear generates piece-wise linear discriminant functions for this dataset. The continuous measurements have previously been discretized by domain experts. NeuroRule is applied to the discretized dataset to generate symbolic classification rules. We compare the rules generated by the two techniques and find that the rules generated by NeuroLinear from the original continuously valued dataset to be slightly more accurate and more concise than the rules generated by NeuroRule from the discretized dataset.     

The rule of rescue

Jonsen coined the term "Rule of Rescue"(RR) to describe the imperative people feel to rescue identifiable individuals facing avoidable death. In this paper we attempt to draw a more detailed picture of the RR, identifying its conflict with cost-effectiveness analysis, the preference it entails for identifiable over statistical lives, the shock-horror response it elicits, the preference it entails for lifesaving over non-lifesaving measures, its extension to non-life-threatening conditions, and whether it is motivated by duty or sympathy. We also consider the measurement problems it raises, and argue that quantifying the RR would probably require a two-stage procedure. In the first stage the size of the individual utility gain from a health intervention would be assessed using a technique such as the Standard Gamble or the Time Trade-Off, and in the second the social benefits arising from the RR would be quantified employing the Person Trade-Off. We also consider the normative status of the RR. We argue that it can be defended from a utilitarian point of view, on the ground that rescues increase well-being by reinforcing people's belief that they live in a community that places great value upon life. However, utilitarianism has long been criticised for failing to take sufficient account of fairness, and the case is no different here: fairness requires that we do not discriminate between individuals on morally irrelevant grounds, whereas being "identifiable" does not seem to be a morally relevant ground for discrimination.     

Validating and updating a prediction rule for serious bacterial infection in patients with fever without source

AIM: To externally validate and update a previously developed rule for predicting the presence of serious bacterial infections in children with fever without apparent source. METHODS: Patients, 1-36 mo, presenting with fever without source, were prospectively enrolled. Serious bacterial infection included bacterial meningitis, sepsis, bacteraemia, pneumonia, urinary tract infection, bacterial gastroenteritis, osteomyelitis/ethmoiditis. The generalizability of the original rule was determined. Subsequently, the prediction rule was updated using all available data of the patients with fever without source (1996-1998 and 2000-2001, n = 381) using multivariable logistic regression. RESULTS: the generalizability of the rule appeared insufficient in the new patients (n = 150). In the updated rule, independent predictors from history and examination were duration of fever, vomiting, ill clinical appearance, chest-wall retractions and poor peripheral circulation (ROC area (95%CI): 0.69 (0.63-0.75)). Additional independent predictors from laboratory were serum white blood cell count and C-reactive protein, and in urinalysis > or = 70 white bloods (ROC area (95%CI): 0.83 (0.78-0.88). CONCLUSIONS: A previously developed prediction rule for predicting the presence of serious bacterial infection in children with fever without apparent source was updated. Its clinical score can be used as a first screening tool. Additional laboratory testing may specify the individual risk estimate (range: 4-54%) further.