6MV X线照射人离体血细胞遗传学剂量—效应研究——常规法的微核剂量效应曲线

本文应用医用直线加速器6MV X 线照射5例健康成人离体血研究淋巴细胞微核与剂量间的关系,发现微核率及微核细胞率可各配以回归方程 Y=6.6896×10~(-3)+1.2959×10~(-2)D~2及 Y=7.3906×10~(-3)+1.0824×10~(-2)D~2,其 R~2值分别为O.9948及0.9976,有较好的拟合度,可作为预测受照剂量的模型。     

Direction selectivity of neurons in the visual cortex is non‐linear and lamina‐dependent

Neurons in the visual cortex are generally selective to direction of movement of a stimulus. Although models of this direction selectivity (DS) assume linearity, experimental data show stronger degrees of DS than those predicted by linear models. Our current study was intended to determine the degree of non‐linearity of the DS mechanism for cells within different laminae of the cat's primary visual cortex. To do this, we analysed cells in our database by using neurophysiological and histological approaches to quantify non‐linear components of DS in four principal cortical laminae (layers 2/3, 4, 5, and 6). We used a DS index (DSI) to quantify degrees of DS in our sample. Our results showed laminar differences. In layer 4, the main thalamic input region, most neurons were of the simple type and showed high DSI values. For complex cells in layer 4, there was a broad distribution of DSI values. Similar features were observed in layer 2/3, but complex cells were dominant. In deeper layers (5 and 6), DSI value distributions were characterized by clear peaks at high values. Independently of specific lamina, high DSI values were accompanied by narrow orientation tuning widths. Differences in orientation tuning for non‐preferred vs. preferred directions were smallest in layer 4 and largest in layer 6. These results are consistent with a non‐linear process of intra‐cortical inhibition that enhances DS by selective suppression of neuronal firing for non‐preferred directions of stimulus motion in a lamina‐dependent manner. Other potential mechanisms are also considered.     

负压封闭辅助引流技术联合锁定接骨板外用技术治疗胫骨中下段开放骨折的临床效果

背景:目前在国内锁定接骨板常作为内固定器材使用,国外仅有少数病例报道将其作为外固定器材使用,而负压封闭辅助引流技术联合锁定接骨板外用治疗开放骨折的病例,鲜有报道。目的:探讨负压封闭辅助引流技术(vacuum-assisted closure,VAC)联合锁定板外用治疗胫骨中下段开放骨折后的临床效果。方法:2010年6月至2011年6月,我院收治胫骨中下段开放骨折患者80例,随机分为A、B两组,每组40例。A组采用负压封闭辅助引流技术联合锁定接骨板外用技术,B组采用外固定架固定术后常规换药治疗。结果:80例患者随访3～12个月,平均7.5个月。A组软组织恢复时间(13.70±1.89)d,B组(18.00±2.82)d;A组肉芽生长时间(4.90±1.10)d,B组(13.40±1.89)d,外固定架持续时间A组(14.30±1.88)d,B组(40.40±5.64)d;A组骨折愈合时间(16.10±1.85)周,B组(29.40±2.91)周;A组总住院天数(4.90±1.10)周,B组(10.90±3.28)周;A组踝关节活动度为34.40°±0.69°,B组20.20°±6.07°。数据对比分析后,A组均优于B组(P<0.05)。结论:负压封闭辅助引流技术联合锁定接骨板外用技术简单,可靠,创伤小,功能恢复快,是治疗胫骨中下段开放骨折的合理方法。     

采用真空封闭引流法治疗心肺手术后切口裂开

目的介绍采用真空封闭引流法(VAC)治疗心肺手术后胸部切口裂开,总结其初期临床经验。方法回顾性分析2010年10月至2011年10月天津武警后勤学院附属医院12例心肺手术后胸部切口裂开患者经VAC治疗的临床资料,男7例,女5例;平均年龄64.3(39～80)岁。均经胸骨正中切口或侧胸切口径路行心肺手术。术后手术切口裂开程度均达胸骨或肋骨。胸部切口经清创后安装VAC装置海绵,使用间断负压仪治疗,7～10 d更换切口负压海绵1次。结果所有使用VAC治疗的患者平均更换VAC海绵材料2次,治疗中切口周围组织水肿消退,切口肉芽新鲜,所有患者全身状况改善,患者可以下床,生活自理,不再使用抗生素。住院医师的主要工作变成每日检查负压辅助装置工作是否正常,患者不再有恐惧和每天换药时的疼痛感。所有患者经治疗后痊愈出院,均在门诊进行随访,平均随访时间7个月,切口愈合牢固,效果满意。结论 VAC使用方便,能迅速促进切口愈合、减轻局部切口和全身炎性反应,加速患者康复,同时减轻了住院医师的工作量,值得临床推广应用。     

State and output feedback design for robust tracking of linear systems with rate limited actuators

A design technique (Control of Uncertain Systems with Bounded Inputs, Tarbouriech S, Garcia G, (Eds), Lecture Notes in Control and Information Sciences, vol. 227 , Springer: Berlin, 1997; 173–186) recently proposed for stabilization of a linear system with rate‐limited actuators is utilized to design feedback laws that cause the system output to track a desired command signal. This design technique combines two design techniques recently developed for linear systems with position limited actuators, piecewise‐linear LQ control (Automatica, 1994; 30 : 403–416) and low‐and‐high gain feedback (IEEE Trans. Automat. Control, 1996; 41 : 368–378), and hence takes advantage of both design techniques, while avoiding their disadvantages. In the case that only the output is available for feedback, the performance of the state feedback law is preserved by the use of a fast observer. An open‐loop exponentially unstable fighter aircraft is used to demonstrate the effectiveness of the proposed control design method. Copyright © 2002 John Wiley & Sons, Ltd.     

Polynomial matrix solution of H2 optimal control problem for state‐space systems

A polynomial matrix solution to the H₂ output feedback optimal control problems is obtained for systems represented in state‐equation form. The proof does not invoke the separation principle but is obtained in the z‐domain. The cost function includes weighted states, which allows the so‐called standard system model problem to be solved. This encompasses the class of inferential control problems. The results also enable the two‐degree‐of‐freedom optimal control solution properties to be explored. Copyright © 2002 John Wiley & Sons, Ltd.     

Cleft closure for the treatment of unhealed perineal sinus

OBJECTIVE: Despite improvements in surgical practice, persistent perineal wound sinus is still a common complication after proctectomy. This study presents the success of a modified cleft closure technique in dealing with this problem. METHODS: From May 1997 patients with a persistent perineal sinus after surgery underwent a cleft closure - similar to that performed for patients with pilonidal sinus disease. RESULTS: Eight patients (6 male, 2 female) with an average age of 52 years underwent a cleft closure for a persistent perineal sinus after surgery. Four patients had undergone a proctocolectomy (ulcerative colitis), 2 an abdominoperineal excision of the rectum (adenocarcinoma) and 2 a proctectomy (1 Crohn's disease, 1 complication of diverticular disease). Symptoms had been present for an average of 41 months (range 5-152 months) and 3 patients had undergone other procedures attempted previously to deal with the problem. The first three patients had the procedure as an inpatient with an average stay of 4.7 days. The next 5 patients had the procedure as a day case (2 local anaesthetic, 3 general anaesthetic). Two patients developed a postoperative wound infection and all but one wound had healed completely by 8 weeks. In this patient the procedure was repeated to achieve healing. There was no other associated morbidity and no postoperative deaths. There have been no recurrences to date. CONCLUSION: Modified cleft closure for persistent perineal sinus is a simple procedure with low morbidity that can be performed under local anaesthetic in the day surgery unit.     

Optimal control of non‐linear chemical reactors via an initial‐value Hamiltonian problem

The problem of designing strategies for optimal feedback control of non‐linear processes, specially for regulation and set‐point changing, is attacked in this paper. A novel procedure based on the Hamiltonian equations associated to a bilinear approximation of the dynamics and a quadratic cost is presented. The usual boundary‐value situation for the coupled state–costate system is transformed into an initial‐value problem through the solution of a generalized algebraic Riccati equation. This allows to integrate the Hamiltonian equations on‐line, and to construct the feedback law by using the costate solution trajectory. Results are shown applied to a classical non‐linear chemical reactor model, and compared against suboptimal bilinear‐quadratic strategies based on power series expansions. Since state variables calculated from Hamiltonian equations may differ from the values of physical states, the proposed control strategy is suboptimal with respect to the original plant. Copyright © 2005 John Wiley & Sons, Ltd.     

Wound conditioning by vacuum assisted closure (V.A.C.) in postoperative infections after dorsal spine surgery

The use of vacuum assisted closure (V.A.C.) therapy in postoperative infections after dorsal spinal surgery was studied retrospectively. Successful treatment was defined as a stable healed wound that showed no signs of acute or chronic infection. The treatment of the infected back wounds consisted of repeated debridement, irrigation and open wound treatment with temporary closure by V.A.C. The instrumentation was exchanged or removed if necessary. Fifteen patients with deep subfascial infections after posterior spinal surgery were treated. The implants were exchanged in seven cases, removed completely in five cases and left without changing in one case. In two cases spinal surgery consisted of laminectomy without instrumentation. In two cases only the wound defects were closed by muscle flap, the remaining ones were closed by delayed suturing. Antibiotic treatment was necessary in all cases. Follow up was possible in 14 patients. One patient showed a new infection after treatment. The study illustrates the usefulness of V.A.C. therapy as a new alternative management for wound conditioning of complex back wounds after deep subfascial infection.     

双镜联合胆总管切开一期缝合治疗胆总管结石的临床体会

目的探讨腹腔镜联合胆道镜胆总管探查一期缝合的安全性及疗效。方法回顾性分析安徽医科大学第二附属医院2015年4月到2017年4月35例腹腔镜联合胆道镜胆总管探查一期缝合患者临床资料。结果 35例患者均行腹腔镜胆总管探查一期缝合,无中转开腹患者。平均胆总管直径12.4mm,平均胆总管结石1.7个,结石即时清除率100%,35例患者胆总管通畅性及Oddi括约肌功能均良好。总体并发症发生率11.4%,全组无Clavien-DindoⅢ级以上并发症发生,术后胆漏发生率5.7%,经充分腹腔引流治愈。术后平均住院时间5.2天,平均住院总费用元20923元。随访率100%,平均随访9.9月,无结石残留、复发或胆管狭窄。结论严格把握手术适应证、由熟练掌握腹腔镜及胆道镜技术的专科医生操作的前提下,腹腔镜胆总管探查取石一期缝合是安全、可行的,且加速患者恢复,减少患者痛苦。