木糖醇发酵动力学研究

根据通用的分批发酵动力学模型,建立了莫格假丝酵母由木糖转化为木糖醇的发酵动力学模型,用遗传算法估算反应动力学模型参数.计算结果表明,该模型能较好地与实验结果相吻合.     

Mm．158494基因在白消安引起的无精子症小鼠中的表达

目的建立一个小鼠无精子症模型,并探讨Mm.158494基因在无精子症中的表达及意义。方法建立无精子症小鼠模型,观察小鼠睾丸生精小管结构的变化。筛选与精子发生相关的睾丸特异性新基因,利用网络信息资源对该基因进行生物学信息分析,RT-PCR分析该基因在无精子症小鼠睾丸中的表达。结果生物信息学分析发现Mm.158494基因cDNA序列全长1046bp,含有762bp的完整开放阅读框。编码253个氨基酸、分子量为29.432kDa的蛋白质。小鼠无精子症模型中微弱表达Mm.158494基因。结论Mm.158494基因在无精子症中表达明显降低,提示该基因可能在精子发生中起重要作用。     

山西省三年间烧伤医疗资源调查及分析

山西省是全国重要的能源化工基地,金属冶炼、煤矿开采相对较多,人们生活习惯亦有别于其他地区,有必要调查分析该地区烧伤患者的流行病学资料.     

山西省三年间烧伤医疗资源调查及分析

山西省是全国重要的能源化工基地,金属冶炼、煤矿开采相对较多,人们生活习惯亦有别于其他地区,有必要调查分析该地区烧伤患者的流行病学资料.     

微生物生长过程中菌体浓度的软测量

菌体浓度是微生物生长过程中关键的质量指标 .作者利用RBF神经网络建立了微生物生长过程中菌体浓度的软测量模型 ,探讨了软测量模型的动态校正方法 ,通过仿真验证了该方法的有效性 .     

山西省三年间烧伤医疗资源调查及分析

山西省是全国重要的能源化工基地,金属冶炼、煤矿开采相对较多,人们生活习惯亦有别于其他地区,有必要调查分析该地区烧伤患者的流行病学资料.     

山西省三年间烧伤医疗资源调查及分析

山西省是全国重要的能源化工基地,金属冶炼、煤矿开采相对较多,人们生活习惯亦有别于其他地区,有必要调查分析该地区烧伤患者的流行病学资料.     

山西省三年间烧伤医疗资源调查及分析

山西省是全国重要的能源化工基地,金属冶炼、煤矿开采相对较多,人们生活习惯亦有别于其他地区,有必要调查分析该地区烧伤患者的流行病学资料.     

山西省三年间烧伤医疗资源调查及分析

山西省是全国重要的能源化工基地,金属冶炼、煤矿开采相对较多,人们生活习惯亦有别于其他地区,有必要调查分析该地区烧伤患者的流行病学资料.     

山西省三年间烧伤医疗资源调查及分析

山西省是全国重要的能源化工基地,金属冶炼、煤矿开采相对较多,人们生活习惯亦有别于其他地区,有必要调查分析该地区烧伤患者的流行病学资料.     

尿动力学参数多元分析对良性前列腺增生所致膀胱出口梗阻的诊断价值

目的:探索用于诊断良性前列腺增生患者合并膀胱出口梗阻(BOO)的函数模型,绘制能用于判断不同的逼尿肌收缩力状况下尤其是逼尿肌收缩力减弱时BOO情况的曲线。方法:回顾性分析131例患者尿动力学的检查结果和临床资料,通过多因素Logistic回归分析的方法,建立函数模型,根据此模型绘制BOO情况判断的曲线。采用ROC曲线分析的方法,确定我们的函数模型和相应曲线诊断BOO的界值。结果:建立的函数模型为BOO指数(BOO I)=5.03×剩余分数+0.04×最大尿流率时的逼尿肌压力-0.20×最大尿流率-0.91+α(当压力流率曲线为低压低流型时α=0;为高压低流型时α=1.42;为高压高流型时α=-7.30)。确定的BOO I诊断BOO的界值为0.36。验证该界值时灵敏度、特异度、阳性预测价值、阴性预测价值分别为85.7%、91.7%、96%、73.3%。结论:我们建立的函数模型BOO I计算公式较为简单,可推测出患者出现BOO概率的大小。诊断标准具有良好的灵敏度和特异度。我们绘制的诊断曲线能够把表现为低压低流型患者中有BOO的患者鉴别出来使之从解除梗阻的手术中获得益处。     

Mammographic sensitivity as a function of tumor size: A novel estimation based on population-based screening data

BackgroundInstead of a single value for mammographic sensitivity, a sensitivity function based on tumor size more realistically reflects mammography’s detection capability. Because previous models may have overestimated size-specific sensitivity, we aimed to provide a novel approach to improve sensitivity estimation as a function of tumor size.MethodsUsing aggregated data on interval and screen-detected cancers, observed tumor sizes were back-calculated to the time of screening using an exponential tumor growth model and a follow-up time of 4 years. From the observed number of detected cancers and an estimation of the number of false-negative cancers, a model for the sensitivity as a function of tumor size was determined. A univariate sensitivity analysis was conducted by varying follow-up time and tumor volume doubling time (TVDT). A systematic review was conducted for external validation of the sensitivity model.ResultsAggregated data of 22,915 screen-detected and 10,670 interval breast cancers from the Dutch screening program were used. The model showed that sensitivity increased from 0 to 85% for tumor sizes from 2 to 20 mm. When TVDT was set at the upper and lower limits of the confidence interval, sensitivity for a 20-mm tumor was 74% and 93%, respectively. The estimated sensitivity gave comparable estimates to those from two of three studies identified by our systematic review.ConclusionDerived from aggregated breast screening outcomes data, our model’s estimation of sensitivity as a function of tumor size may provide a better representation of data observed in screening programs than other models.     

Derivation and validation of a model to predict acute kidney injury following cardiac surgery in patients with normal renal function

BackgroundThe study aimed to construct a clinical model based on preoperative data for predicting acute kidney injury (AKI) following cardiac surgery in patients with normal renal function.MethodsA total of 22,348 consecutive patients with normal renal function undergoing cardiac surgery were enrolled. Among them, 15,701 were randomly selected for the training group and the remaining for the validation group. To develop a model visualized as a nomogram for predicting AKI, logistic regression was performed with variables selected using least absolute shrinkage and selection operator regression. The discrimination, calibration, and clinical value of the model were evaluated.ResultsThe incidence of AKI was 25.2% in the training group. The new model consisted of nine preoperative variables, including age, male gender, left ventricular ejection fraction, hypertension, hemoglobin, uric acid, hypomagnesemia, and oral renin-angiotensin system inhibitor and non-steroidal anti-inflammatory drug within 1 week before surgery. The model had a good performance in the validation group. The discrimination was good with an area under the receiver operating characteristic curve of 0.740 (95% confidence interval, 0.726–0.753). The calibration plot indicated excellent agreement between the model prediction and actual observations. Decision curve analysis also showed that the model was clinically useful.ConclusionsThe new model was constructed based on nine easily available preoperative clinical data characteristics for predicting AKI following cardiac surgery in patients with normal kidney function, which may help treatment decision-making, and rational utilization of medical resources.     

Assessing insulin secretion by modeling in multiple-meal tests: role of potentiation

We developed a mathematical model of the glucose control of insulin secretion capable of quantifying beta-cell function from a physiological meal test. The model includes a static control, i.e., a secretion component that is a function of plasma glucose concentration (the dose-response function), and a dynamic control, i.e., a secretion component that is proportional to the positive values of the glucose concentration derivative. Furthermore, the dose-response function is assumed to be modulated by a time-varying potentiation factor. To test the model, nine nondiabetic control subjects and nine type 2 diabetic patients received three standardized mixed meals over a period of 14-15 h. Blood samples were drawn for the measurement of glucose, insulin, and C-peptide concentration. The dose-response function, the parameter of the dynamic control, and the potentiation factor were determined by fitting the model to glucose and C-peptide concentrations. In diabetic patients, the dose-response function was shifted to the right (glucose concentration at a reference insulin secretion of 300 pmol.min(-1).m(-2) was 11.7 +/- 1.1 vs. 7.2 +/- 0.7 mmol/l; P < 0.05), and decreased in slope (53 +/- 15 vs. 148 +/- 38 pmol.min(-1).m(-2).mmol(-1).l; P < 0.05) and the parameter of the dynamic control was decreased (220 +/- 67 vs. 908 +/- 276 pmol.m(-2).mmol(-1).l; P < 0.05) compared with the nondiabetic control subjects. Furthermore, potentiation was markedly blunted and delayed: maximum potentiation was observed at the first meal in normal subjects and at the second meal (about 4 h later) in diabetic subjects; the mean time for the potentiation factor was higher (7.1 +/- 0.2 vs. 5.9 +/- 0.2 h; P < 0.01), and the size of potentiation was reduced (2.6 +/- 0.5 vs. 7.2 +/- 1.5 fold increase; P < 0.005). In conclusion, our model of insulin secretion extracts multiple indexes of beta-cell function from a physiological meal test. Use of the model in patients with type 2 diabetes retrieves known defects in insulin secretion but also uncovers new facets of beta-cell dysfunction.     

应用节段性兔股薄肌肌皮瓣重建阴茎勃起功能的研究

目的 设计应用节段性兔股薄肌肌皮瓣构建再造阴茎、重建勃起功能的动物模型.方法 依据肌亚部原则,近似二等分纵向完全劈开兔股薄肌,以前部肌束作为功能单位和皮瓣血供来源,植入硅胶假体作为支撑,构建阴茎再造的动物模型.应用多道生理信号采集处理系统刺激再造阴茎活动,并同步检测复合肌肉动作电位.结果 通过电刺激兔再造阴茎根部的神经,可使前部肌束收缩,引起阴茎形态的相应改变,当肌束发生强直收缩时,再造阴茎上翘幅度最大,并可维持翘起状态数秒,较满意地模拟了阴茎的勃起动作.结论 应用节段性兔股薄肌肌皮瓣构建的再造阴茎动物模型,较满意地重建了阴茎勃起功能,达到了兼顾改善阴茎外观与保留肌肉收缩功能的要求,具有较好的临床应用前景.     

TNF-α抑制剂对重症急性胰腺炎大鼠凝血功能及钙离子的影响

【摘要】 目的 分析TNF-α抑制剂对重症急性胰腺炎(SAP)大鼠凝血功能及钙离子的影响,为TNF-α抑制剂治疗SAP提供实验依据。方法〓制做SAP大鼠模型;对照组:假注射组,20只,制备成SAP模型,尾部注射生理盐水;治疗组:SAP模型大鼠60只,治疗组1、治疗组2、治疗组3三个亚组各20只,模型制作成功后,分别按照0.15 mg/kg、0.30 mg/kg、0.45 mg/kg剂量水平,经阴茎背静脉注射TNF-α抑制剂;24 h后,麻醉,采血针抽取各组大鼠颈总动脉血3 mL,行凝血系列检测及观察血钙水平。结果〓试验期间,大鼠均存活,治疗组大鼠状态稍好,部分仍有自主活动、进食;治疗组1、治疗组2、治疗组3的APPT、FIB水平低于假注射组,治疗组血清离子钙水平高于假注射组;治疗组内3组间PT、APPT、FIB、血清离子钙比较差异具有统计学意义(P<0.05),治疗组内3组间血清总钙比较差异无统计学意义(P>0.05)。结论〓SAP可致大鼠凝血功能减退,血钙水平降低,TNF-α抑制剂有助于改善SAP模型大鼠凝血功能及血清离子钙水平,作用机制与抑制炎症反应有关,且呈较明显的剂量依赖,在0.45 mg/kg剂量水平,改善效果更显著。     

Relative contributions of age and menopause to the vertebral bone density of healthy Japanese women

The relative contributions of age and menopause to vertebral bone mineral density were evaluated based on the estimated weights for age- and menopause-related bone loss components using a mathematical model in 177 healthy female volunteers ages 35–81 years, living in a community in Fukui, Japan. Bone mineral density was determined by dual X-ray absorptiometry. The model used was that which afforded the best fit among the eight possible models to the data observed. Each model was composed of a linear function for the age-related component and a different type of function for the menopausal component, without interaction between them. The weights for these components in each model were estimated by the least-squares method. The coefficient of determination and Akaike information criterion disclosed that among the eight models tested, the model affording the best fit was composed of a logarithmic decrease in bone density with an increase in years since menopause, up to 10 years postmenopausal, with no further decline thereafter. In this model, the weights for both components were statistically significant and the type III sum of squares of the menopausal component was greater than that of the age-related component. We suggest that both age and menopause made significant contributions to the decline in vertebral bone mineral density, with the contribution of menopause being greater than that of age.     

Liver transplantation in swine: a model for tolerance induction

AIM: The liver as a solid graft has a known immunological privilege. Its tolerogenic property has been demonstrated in rodents. In humans the onset of chronic rejection and the severity of such complication is less frequent after liver transplantation compared to other organs. The underlying events whose effect is graft acceptance instead of rejection should be further investigated. Their control could open new ways to decrease the need for long-term immunosuppression after transplantation of other organs. Aim of this study is to evaluate a model of liver transplantation in swine as a preliminary step for immunological studies. METHODS: Ten outbred Landrace/Large White mismatched swine underwent to liver transplantation with a simple passive portocaval jugular bypass. The onset of rejection was monitored daily by liver function test. After death or sacrifice the liver parenchyma was studied to evaluate tissue damage and inflammatory infiltrate. RESULTS: The postoperative liver function showed a critical period for organ rejection about postoperative day 5. The animals that survived longer were sacrificed with a normal biochemical hepatic function. However, histology consistently showed a pattern of mild rejection in a still preserved architecture. CONCLUSIONS: The evidence of a prolonged liver function in a rejecting model of liver transplantation makes this model suitable for studies of tolerance induction.     

Mitochondrial death in sepsis: a failed concept

The concept of early selective mitochondrial injury has been proposed to explain the global metabolic dysfunction observed in the septic state. A two phase study was undertaken to test the validity of this hypothesis. In the initial phase, an endotoxin shock model was employed in the rat to delineate the function of skeletal muscle mitochondria. Mitochondrial function was determined polarimetrically, comparing state three and state four rates, respiratory control index (RCI) and ADP:O ratios. No significant alteration in these parameters was observed in the endotoxic state. Phase II of the study was designed to investigate mitochondrial function in a bacterial peritonitis rat model. Both liver and skeletal muscle mitochondrial function were determined to control for possible alterations in liver metabolism. Neither muscle nor liver mitochondria exhibited functional impairment during sepsis. We conclude from this study that neither endotoxemia nor peritonitis selectively "kills" mitochondria as previously suggested.     

The development of a short measure of physical function for hip OA HOOS-Physical Function Shortform (HOOS-PS): an OARSI/OMERACT initiative

OBJECTIVE: To derive a cross-culturally valid, short measure of physical function using function subscales (daily living and sports and recreation) of the Hip disability and Osteoarthritis Outcome Score (HOOS). METHODS: Rasch analysis was conducted on data from individuals from multiple countries who had hip osteoarthritis (OA). Fit of the data to the Rasch model was evaluated by model chi(2) and item fit statistics (chi(2), size of residual, and F-test). Differential item functioning was evaluated by gender, age and country. Unidimensionality was evaluated by factor analysis of residuals. Individual data sets were analyzed and data pooled and re-analyzed for fit to the model. Regression modeling was conducted to derive a nomogram converting raw summed scores to Rasch derived interval scores. RESULTS: Seven data sets were included (n=2991), ages 19-96 years, male/female ratio was 1:1.23. The final model included five HOOS items. From the easiest to most difficult, the items (logit) were as follows: sitting (1.832), descending stairs (0.729), getting in/out of bath or shower (0.255), twisting/pivoting on loaded leg (-0.221) and running (-2.595). The separation index was 0.80. CONCLUSION: The daily activity and sports and recreational items of the HOOS were reduced to five items achieving a feasible, short measure of physical function with interval level properties. This tool has potential for use as the function component of an OA severity scoring system. Further testing of this measure is warranted.