Rejection of persistent‐bounded disturbances in continuous time‐delay systems using observer‐based feedback

In this paper, the problem of persistent‐bounded disturbance rejection of linear continuous‐time systems with time‐varying delays is investigated using the tools of invariant set analysis and Lyapunov‐function methodology. We derive less conservative sufficient conditions on robust attractor for time‐delay systems in terms of strict linear matrix inequalities (LMIs) to guarantee the desired ??₁‐performance. A robust output‐feedback controller is designed and the associated gain is determined using strict LMIs. The developed results are tested on two representative time‐delay examples. Copyright © 2009 John Wiley & Sons, Ltd.     

Venous drainage in retrograde island flap: An experimental study using fluorescence tracing technique

The pathway of venous drainage in retrograde island flaps was investigated by fluorescence tracing technique using the saphenous fasciocutaneous flap in New Zealand White rabbits. Forty animals were allocated into four groups according to the different times at 30 minutes (I), 24 hours (II), 72 hours (III), and 7 days (IV) after the operation. According to the different routes to give tracer, each group was further allocated into two subgroups of the artery injection and vein injection. For each animal, one hindlimb was assigned as the experimental side, the contralateral side as control without giving tracer. The erythrocytes were separated, labeled with fluorescein isothiocyanate (FITC), detected, and injected into the artery or vein. Subsequently, the flaps were harvested 5 seconds after injection and immediately frozen, sectioned, and observed under microscope. In group I and II, the fluorescence was observed mainly around the vessel adventitia of the vein and artery and tunica intima of the artery. In group III, there was weak fluorescence observed in the lumen of vein. In group IV, fluorescence was distributed principally in the lumen of the vein. In addition, fluorescence was not observed in the saphenous nerve in group I and there was mild fluorescence in the saphenous nerve in groups II, III, and IV. These findings suggest that the venous return is through “bypass route” in earlier period. In later period, the venous retrograde return is through “bypass route” and “incompetent valves route;” however, “incompetent valves route” becomes the main route. © 2009 Wiley‐Liss, Inc. Microsurgery 2010.     

Monitoring sedation in the critically ill child

Sedation is an essential part of the management of the critically ill child, and its monitoring must be individualised and continuous in order to adjust drug doses according to the clinical state. There is no ideal method for evaluating sedation in the critically ill child. Haemodynamic variables have not been found to be useful. Clinical scales are useful when sedation is moderate, but are limited by their subjective nature, the use of stimuli, and the impossibility of evaluating profoundly sedated patients or those receiving neuromuscular blocking drugs; in addition, many of these scales have not been evaluated in children. The COMFORT scale is the most appropriate, as it was designed and validated for critically ill children requiring mechanical ventilation. Electroencephalography‐derived methods permit continuous monitoring, provide an early indication of changes in the level of sedation, and facilitate a rapid adjustment of medication. However, these methods were designed and validated for patients under anaesthesia and their results cannot be fully extrapolated to the critically ill patient; in addition, some of them have not been validated in small children and there is still little experience in critically ill children. The main indications for the use of these methods are in patients with deep sedation and/or neuromuscular blockade. The bispectral index is the most widely used method at the present time. Analysis and comparison of the efficacy of the different methods for evaluating sedation in the critically ill child is required.     

A health‐economic analysis of porcine islet xenotransplantation

Beckwith J, Nyman JA, Flanagan B, Schrover R, Schuurman H‐J. A health‐economic analysis of porcine islet xenotransplantation. Xenotransplantation 2010; 17: 233–242. © 2010 John Wiley & Sons A/S. Abstract: Background: Islet cell transplantation is a promising treatment for type 1 diabetes. To overcome the shortage of deceased human pancreas donors, porcine islet cell xenotransplantation is being developed as an alternative to allotransplantation. The objective of this study was to perform a cost‐effectiveness analysis of porcine islet transplantation in comparison with standard insulin therapy. The patient population for this study was young adults, ages 20 to 40, for whom standard medical care is inadequate in controlling blood glucose levels (hypoglycemia unawareness). Since trial data were lacking, estimates used extrapolations from data found in the literature and ongoing trials in clinical allotransplantation. Cost estimates were based on the data available in the USA. Methods: Markov modeling and Monte Carlo simulations using software specifically developed for health‐economic evaluations were used. Outcomes data for ongoing clinical islet allotransplantation from the University of Minnesota were used, along with probabilities of complications from the Diabetes Control and Complications Trial. Quality‐adjusted life years (QALYs) were the effectiveness measure. The upper limit of being cost‐effective is $100 000 per QALY. Cost data from the literature were used and adjusted to 2007 US dollars using the medical care portion of the Consumer Price Index. Results: In both Markov modeling and Monte Carlo simulations, porcine islet xenotransplantation was both more effective and less costly over the course of the 20‐yr model. For standard insulin therapy, cumulative cost per patient was $661 000, while cumulative effectiveness was 9.4 QALYs, for a cost of $71 100 per QALY. Transplantation had a cumulative cost of $659 000 per patient, a cumulative effectiveness of 10.9 QALYs, and a cost per QALY of $60 700. Islet transplantation became cost‐effective at 4 yr after transplantation, and was more cost‐effective than standard insulin treatment at 14 yr. These findings are related to relative high costs in the transplantation arm of the evaluation during the first years while those in the insulin arm became higher later in follow‐up. Throughout the follow‐up period, effectiveness of transplantation was higher than that of insulin treatment. In sensitivity analysis, duplication or triplication of one‐time initial costs such as costs of donor animal, islet manufacturing and transplantation had no effect on long‐term outcome in terms of cost‐saving or cost‐effectiveness, but the outcome of transplantation in terms of diabetes complications in cases with partial graft function could affect cost‐saving and cost‐effectiveness conclusions. Conclusion: Despite limitations in the model and lack of trial data, and under the assumption that islet transplantation outcomes for young adult type 1 diabetes patients are not dependent on the source of islet cells, this health‐economic evaluation suggests that porcine islet cell xenotransplantation may prove to be a cost‐effective and possibly cost‐saving procedure for type 1 diabetes compared to standard management.     

Effects of sevoflurane on collagen production and growth factor expression in rats with an excision wound

Background: Sevoflurane is a widely used inhalation anesthetic, but there are no studies on its effect on the wound‐healing process. This study was undertaken to evaluate the effect of exposure time to sevoflurane on wound healing. Method: Male Sprague–Dawley rats were used. Two circular full‐thickness skin defects 8 mm in diameter were made on the dorsum of the rats. The animals were divided into six groups according to exposed gas type and time: S1 (sevoflurane, 1 h), S4 (sevoflurane, 4 h), S8 (sevoflurane, 8 h), O1 (oxygen, 1 h), O4 (oxygen, 4 h), and O8 (oxygen, 8 h). The surface area of the wounds was measured 0, 1, 3, and 7 days after surgery. Separately, the mean blood pressures (MBP) and arterial oxygen pressures (PaO₂) were monitored during the sevoflurane exposure. Collagen type I production and transforming growth factor‐β1 (TGF‐β1) and basic fibroblast growth factor (bFGF) expression on the wound surface were analyzed. Routine histological analysis was also performed. Result: Exposure duration to sevoflurane had no influence on MBP and PaO₂. The reduction in wound size and collagen type I production was delayed in S8. The expression of TGF‐β1 and bFGF on the wound surface in S8 was significantly attenuated in S8. The histology of the S8 demonstrated a delayed healing status. Conclusions: Prolonged exposure to sevoflurane might alter the inflammatory phase of the wound‐healing process by attenuation of growth factor expression such as TGF‐β1 and bFGF and subsequently by reduced collagen production.     

Short‐term renal outcomes in African American and Caucasian donors following live kidney donation

Reeves‐Daniel A, Freedman BI, Assimos D, Hartmann EL, Bleyer A, Adams PL, Westcott C, Stratta RJ, Rogers J, Farney AC, Daniel KR. Short‐term renal outcomes in African American and Caucasian donors following live kidney donation.
Clin Transplant 2009 DOI: 10.1111/j.1399‐0012.2009.01170.x
© 2009 John Wiley & Sons A/S. Abstract: Introduction: Although African Americans (AA) are considered higher risk kidney donors than Caucasians, limited data are available regarding outcomes of AA donors. Methods: We performed a single‐center retrospective review of all kidney donors from 1993 to 2007 and evaluated race/ethnic differences in post‐donation changes in renal function, incident proteinuria, and systolic blood pressure (SBP) using linear mixed models. Results: A total of 336 kidney donors (63 AA, 263 Caucasian, 10 other) were evaluated. Before donation, AA had higher serum creatinine concentrations, estimated glomerular filtration rate (GFR) values, and SBP levels than Caucasians. No significant changes in SBP or renal function were observed between the two groups within the first year after donation, although results were limited by incomplete follow‐up. Conclusion: AA had higher pre‐donation serum creatinine, GFR, and SBP values compared to Caucasians; however, the degree of change in renal function and blood pressure did not differ between groups following kidney donation. Although long‐term studies are needed, our study suggests that AA and Caucasians experience similar short‐term consequences after donation. The incomplete data available on donor outcomes in our center and in prior publications also indicates a global need to implement systems for structured follow‐up of live kidney donors.     

不同中国肝癌分期肝癌根治性切除术后的临床效果及预后因素分析

目的探讨不同中国肝癌分期(CNLC)肝癌接受根治性切除术后的临床效果及长期生存的预后因素。方法回顾性分析2010年1月至2019年12月南京医科大学第一附属医院肝胆中心单一治疗组收治的行肝癌根治术的549例肝细胞癌(HCC)患者的临床病理学资料。男性462例(84.2%),女性87例(15.8%);中位年龄57岁(范围:21~84岁)。观察患者的术前变量、术中及术后情况、术后病理学检查结果等。采用门诊与电话相结合的方式进行随访。采用寿命表法进行生存率的估计,采用Kaplan-Meier法绘制总体生存和无瘤生存曲线,采用Log-rank检验比较不同组别生存过程的差异,采用多因素Cox回归模型分析影响预后的主要因素。结果 549例HCC患者中,CNLC Ⅰa期200例(36.4%),CNLC Ⅰb 期148例(27.0%),CNLC Ⅱa期49例(8.9%),CNLC Ⅱb期32 例(5.8%),CNLC Ⅲa期101例(18.4%),CNLC Ⅲb期19例(3.5%)。患者1、3、5、10年总体生存率分别为83.8%、69.0%、54.2%、37.7%,1、3、5年无瘤生存率分别为61.0%、44.2%、36.0%。CNLC Ⅰa期患者的1、3、5年总体生存率和无瘤生存率分别为97.3%、90.6%、80.5%和83.9%、65.0%、54.0%;CNLC Ⅰb期患者的1、3、5年总体生存率和无瘤生存率分别为87.9%、71.0%、47.7%和58.4%、42.3%、33.4%;CNLC Ⅱa和Ⅱb期患者的5年总体生存率(Ⅱa期:37.2%,Ⅱb期:44.3%)与CNLC Ⅰb期类似。CNLC Ⅲb期患者 1、3、5年总体生存率和无瘤生存率分别为35.3%、13.2%、0和23.5%、0、0。单因素分析结果显示,术前合并症状、术前甲胎蛋白水平、术前总蛋白水平、术前AST水平、术前总胆红素水平、术中出血量、术中或术后输血、术后并发症、肿瘤最大径和数目、微血管侵犯、大血管侵犯、肿瘤分化程度是HCC患者长期生存(≥5年)的预后因素(P值均<0.05)。多因素分析结果显示,术前AST水平、术中出血量、肿瘤数目、肿瘤最大径、大血管侵犯和肿瘤分级是HCC患者长期生存的独立预后因素(P值均<0.05)。结论不同CNLC的HCC患者具有不同的复发模式及预后。经过严格术前评估的CNLC Ⅱa~Ⅲb期HCC患者可从外科根治切除术中获得生存获益。术前AST水平、术中出血量、肿瘤数目、肿瘤最大径、大血管侵犯和肿瘤分化程度是影响HCC患者长期生存的独立预后因素。