β-内酰胺类抗生素在胆汁中的浓度和药动学的实验研究

目的 研究β-内酰胺类抗生素在胆汁中的浓度及其药动学,并对杀菌效力进行评估,为临床上肝胆系统感染选择用药提供参考和依据.方法 家兔行胆总管造瘘术,分别静脉注射哌拉西林/他唑巴坦、头孢曲松和美罗堵南等β-内酰胺类抗生素后于不同时间收集胆汁标本,采用HPLC法测定各抗生素的浓度,并计算出药动学参数.结合最低抑菌浓度(MIC),评估抗生素在胆汁中的杀菌效力.结果 各抗生素在胆汁中的峰浓度和半衰期分别为:哌拉西林(7950.16±3023.00)μg/ml和(1.97±1.23)h,头孢曲松(1107.01±247.61)μg/ml和(3.14±0.57)h,美罗培南(31.97±12.44)μg/ml和(0.36±0.11)h.哌拉西林/他唑巴坦的杀菌指数最大、TMIC最长,对大部分胆道感染常见致病菌均可形成MIC90 100倍以上的浓度,TMIC长达6～8 h;头孢曲松和美罗培南较低.结论 哌拉西林、头孢曲松和美罗培南均可在胆汁中达到有效杀菌浓度,哌拉西林/他唑巴坦杀菌效力最强.     

常用抗生素在动物及人胆汁中的浓度分布和药效学研究

目的研究常用抗生素在胆汁中的浓度和对致病菌的抗菌活性。方法分别静脉注射常用6种抗生素后于不同时间收集家兔胆汁标本，采用高效液相色谱法测定各抗生素的浓度，计算出药动学参数；测定胆道手术患者胆汁常用5种抗生素浓度，对临床分离的157株胆道细菌进行抗菌活性分析。结果家兔胆汁平均药峰浓度较高的为：哌拉西林7950．16μg／ml，头孢哌酮5274．52μg／ml，头孢曲松1107．01μg/ml。在患者胆总管和胆囊胆汁中的平均浓度较高的为：头孢哌酮／舒巴坦563．75／14．76和169．90／8．83μg／ml，哌拉西林／他唑巴坦350．38／16．69和139．81／15．92μg／ml，头孢曲松249．78和82．06μg／ml。美罗培南和莫西沙星的体外抗菌活性最强，增加β-内酰胺酶抑制剂后的哌拉西林和头孢哌酮复合制剂较单一制剂的抗菌活性显著增强。头孢哌酮／舒巴坦、哌拉西林／他唑巴坦、莫西沙星对胆道致病菌的杀菌指数最大。结论家兔胆汁中6种测定的抗生素均超过有效杀菌浓度，哌拉西林、头孢哌酮、头孢曲松胆汁药物浓度很高。头孢哌酮／舒巴坦和哌拉西林／他唑巴坦、莫西沙星在人胆汁中杀菌效力最强，可作为肝胆系统感染经验治疗的首选用药。     

三种碳青霉烯类抗菌药物联用头孢哌酮舒巴坦对耐碳青霉烯鲍曼不动杆菌的抗菌活性分析

目的：探讨亚胺培南、美罗培南、厄他培南3种碳青霉烯类抗菌药物与头孢哌酮舒巴坦联用,对耐碳青霉烯鲍曼不动杆菌的抗菌活性。方法分别检测亚胺培南、美罗培南、厄他培南对36株耐碳青霉烯鲍曼不动杆菌的最小抑菌浓度（MIC）值,及3种抗菌药物与头孢哌酮舒巴坦联用的部分抑菌浓度（FIC）指数,计算3种碳青霉烯抗菌药物与头孢哌酮舒巴坦联用累计抑菌率曲线。结果36株泛耐药鲍曼不动杆菌,亚胺培南、美罗培南MIC50为16 mg/L,亚胺培南MIC90为64 mg/L;美罗培南MIC90为128 mg/L。厄他培南MIC50为32 mg/L,MIC90为256 mg/L。亚胺培南、美罗培南、厄他培南与头孢哌酮舒巴坦联用,FIC指数≤0.5、0.5～1、1～2和＞2者分别为1株、16株、14株、5株;1株、17株、13株和5株;0株、1株、30株和5株。三种药物与头孢哌酮舒巴坦联用后,亚胺培南累计抑菌率曲线左移,美罗培南累计抑菌率曲线改变不明显;厄他培南联用后,累计抑菌率曲线轻度右移。结论亚胺培南、美罗培南与头孢哌酮舒巴坦联用对耐碳青霉烯鲍曼不动杆菌多数呈相加或无关作用,厄他培南与头孢哌酮舒巴坦联用呈无关作用;3种碳青霉烯抗菌药物与头孢哌酮舒巴坦对部分耐碳青霉烯鲍曼不动杆菌具有拮抗作用。     

抗菌药物用药频度与铜绿假单胞菌和鲍曼不动杆菌耐药率的相关性

目的分析抗菌药物用药频度与铜绿假单胞菌和鲍曼不动杆菌耐药率的相关性,为临床合理使用抗菌药物,降低细菌耐药率提供依据。 方法对云南省第三人民医院2013年1月至2017年12月年常用抗菌药物用药频度以及同期分离的铜绿假单胞菌和鲍曼不动杆菌耐药情况进行回顾性调查分析。 结果本院抗菌药物2014年用药频度（28 809）较2013年（16 259）显著上升,铜绿假单胞菌对头孢曲松、头孢吡肟、氨曲南、庆大霉素、左氧氟沙星、亚胺培南、美罗培南、头孢哌酮/舒巴坦和哌拉西林/他唑巴坦的耐药率,鲍曼不动杆菌对头孢曲松、头孢吡肟、庆大霉素、亚胺培南、美罗培南、头孢哌酮/舒巴坦和哌拉西林/他唑巴坦抗菌药物的耐药率亦有所上升。鲍曼不动杆菌对头孢哌酮/舒巴坦较敏感,但对其他常用抗菌药物的耐药率,特别是对头孢类（平均耐药率为78.23%）和碳青霉烯类药物（平均耐药率为72.69%）的耐药率仍居高不下。抗菌药物年用药频度分析结果显示,2013年至2017年铜绿假单胞菌耐药率与左氧氟沙星用药频度呈高度正相关（r = 0.70、P = 0.20）;鲍曼不动杆菌耐药率与美洛培南用药频度呈显著正相关（r = 0.94、P = 0.02）。 结论本院所分离铜绿假单胞菌耐药率与左氧氟沙星用药频度,鲍曼不动杆菌耐药率与美洛培南用药频度均呈显著正相关,为避免常见的感染菌和定植菌耐药的发生,应加强抗菌药物的监管。     

胆石症合并急性胆管炎患者胆汁及血液病原菌培养及药敏分析

目的观察胆石症合并急性胆管炎患者胆汁及血液中病原菌的分布特征、培养阳性率及其对抗菌药物的敏感性,指导临床合理选择和应用抗菌药物。方法选取2011年1月至2014年1月本院消化内科诊断为急性胆道感染、经内镜逆行性胰胆管造影术(ERCP)术中证实存在结石的97例患者的胆汁标本,所有胆汁标本均进行普通细菌、厌氧菌及真菌培养,其中33例行血培养,分别对其病原菌培养及药敏结果进行分析,同时对97例患者术前经验性应用的抗菌药物情况进行统计分析。结果 97例胆汁培养者中73例检出病原菌,阳性率为75.3%。胆汁标本中共分离出病原菌77株,其中革兰阴性菌60珠,革兰阳性菌14株,真菌3株,革兰阴性菌中排名居前3位的细菌分别是大肠埃希菌(43株,55.8%)、克雷伯菌属(6株,7.8%)、阴沟肠杆菌(4株,5.2%)。33例血培养者17例检出病原菌,阳性率为51.5%。血培养中分离出病原菌17株,大肠埃希菌15株,肺炎克雷伯菌1株,梭杆菌属1株。革兰阴性菌对头孢哌酮/舒巴坦、哌拉西林/他唑巴坦和阿米卡星敏感性较高(敏感率分别为93.3%、88.3%和83.3%),未发现对亚胺培南及美罗培南耐药者。对氨曲南和左氧氟沙星敏感性最低(敏感率均为23.0%)。97例患者术前均经验性应用抗菌药物,55例应用单一抗菌药物抗感染,主要为左氧氟沙星(34/55),其次为头孢哌酮/舒巴坦(11/55)和其他(10/55);42例两联抗感染治疗,主要为左氧氟沙星+甲硝唑(16/42)、头孢哌酮/舒巴坦+甲硝唑(15/42)和其他(11/42)。结论胆石症合并急性胆道感染者胆汁中及血液中的主要病原菌为革兰阴性菌,且均以大肠埃希菌为主。头孢哌酮/舒巴坦、哌拉西林/他唑巴坦、阿米卡星敏感性较高,可作为首选抗菌药物,亚胺培南、美罗培南作为备选抗菌药物,在严重感染或其他抗菌药物无效的情况下考虑使用。左氧氟沙星、氨曲南在胆道结石并胆道感染者中耐药率高,临床上经验性应用抗菌药物时应避免选用。     

美罗培南在家兔胆汁中的药物浓度-时间分布的实验研究

目的研究美罗培南在家兔胆汁中的浓度及其分布规律,为预防和治疗胆道感染用药提供参考和依据。方法家兔行胆总管造瘘术,先留取空白胆汁,静脉注射美罗培南后分别于不同时间点采集胆汁标本。行专属性试验后,取空白胆汁加美罗培南对照品和流动相,配成0.5~500μg/ml不同浓度的系列胆汁样品,经高效液相色谱仪分析,采用外标法行药物色谱峰面积定量,以胆汁样品药物浓度对色谱峰面积进行线性回归,得回归方程。注射美罗培南后的家兔胆汁样品经预处理后用高效液相色谱仪测定峰面积,按标准曲线回归方程计算得出胆汁药物浓度,从而了解美罗培南的胆汁药物浓度-时间分布情况。结果专属性试验显示,在本研究的流动相色谱条件下测定药物,胆汁杂质峰、美罗培南药物色谱峰分离效果良好。标准曲线回归方程为S=2209.10C-1251.34,r=0.9999,美罗培南的最低定量限为0.5μg/ml。家兔静脉注射美罗培南(75mg/kg)后即时在胆汁中达(38.36±14.17)μg/ml,远远超过其对革兰阴性杆菌的最小抑菌浓度(MIC90)0.031~2μg/ml,之后美罗培南的胆汁药物浓度随时间而迅速降低。用药后180min,胆汁中的药物均被完全消除。结论美罗培南在胆汁中能达到较高的有效杀菌浓度,可作为预防和治疗胆道感染的较佳的药物。由于消除速度较快,临床用药应缩短间隔时间。     

评估纸片扩散法与Vitek-2 Compact仪器法检测洋葱伯克霍尔德菌体外药物敏感性

目的评估纸片扩散法与Vitek-2 Compact仪器法检测洋葱伯克霍尔德菌体外药敏试验的可靠性。 方法收集2017年1月至2017年12月绍兴市人民医院临床分离到的34株洋葱伯克霍尔德菌,分别采用纸片扩散法、Vitek-2 Compact仪器法和微量肉汤稀释法检测其对头孢他啶、复方磺胺甲噁唑、左氧氟沙星、哌拉西林/他唑巴坦、替加环素、美罗培南、氯霉素、米诺环素和头孢哌酮/舒巴坦共9种抗菌药物的体外敏感性。以微量肉汤稀释法为参考方法,分别评估纸片扩散法、Vitek-2 Compact仪器法与参考方法的分类一致率（CA%）。 结果微量肉汤稀释法检测头孢他啶、复方磺胺甲噁唑、左氧氟沙星、美罗培南和氯霉素5种抗菌药物95%可信区间（95%CI）分别为6.2～13.2、0.5～0.8、3.8～6.3、3.7～7.3和5.0～10.0;纸片扩散法检测头孢他啶、复方磺胺甲噁唑、替加环素、氯霉素和米诺环素的体外敏感性结果与参考方法一致率均> 90%;Vitek-2 Compact检测头孢他啶、复方磺胺甲噁唑和左氧氟沙星的体外敏感性结果与参考方法的一致率均> 90%;纸片扩散法和Vitek-2 Compact仪器法检测哌拉西林/他唑巴坦体外敏感性与参考方法一致率最低,均< 80%;Vitek-2 Compact检测替加环素的大错误（ME）为50%;以微量肉汤稀释法为标准,体外敏感性最好的抗菌药物为复方磺胺甲噁唑和米诺环素（均为100%）,敏感性最差的抗菌药物为左氧氟沙星（38.2%）。 结论纸片扩散法和Vitek-2 Compact仪器法检测洋葱伯克霍尔德菌体外药物敏感性,对头孢他啶和复方磺胺甲噁唑均具有较好的可靠性;应用纸片扩散法检测哌拉西林/他唑巴坦和头孢哌酮/舒巴坦的药物敏感性时,应注意可能出现极大错误（VME）及ME。     

348例肝胆疾病患者胆汁病原菌构成及耐药性分析

目的了解肝胆系统疾病患者中胆汁病原菌构成比及其耐药性分析,以期指导临床合理选用抗菌药物。方法采用回顾性研究方法,收集2017年1～12月我院348例肝胆系统疾病患者送检的胆汁培养的细菌种类鉴定和药敏试验结果。结果送检胆汁培养标本348份,检出病原菌254株,其中革兰阴性菌194株(76. 38%),革兰阳性菌57株(22. 44%),真菌3株(1. 18%)。最常见的病原菌依次为大肠埃希菌69株(27. 17%)、肺炎克雷伯菌53株(20. 87%)、肠球菌36株(14. 17%)、阴沟肠杆菌20株(7. 87%)、铜绿假单胞菌和鲍氏不动杆菌各8株(3. 15%)。大肠埃希菌对亚胺培南、美罗培南、头孢哌酮/舒巴坦的耐药率最低,肺炎克雷伯菌对替卡西林-棒酸、阿莫西林/棒酸、头孢哌酮/舒巴坦的耐药率最低,阴沟肠杆菌对头孢吡肟、庆大霉素、哌拉西林/他唑巴坦、阿米卡星、美罗培南的耐药率最低。肠球菌中并未发现对万古霉素、利奈唑胺和达托霉素的耐药菌株。结论肝胆系统疾病患者胆汁中的病原菌对大多数常用抗菌药物均产生了不同程度的耐药性,临床应尽早根据药敏试验结果合理选用抗菌药物。     

利用秩和比法筛选尿石症合并尿路感染患者的经验性抗生素

目的利用秩和比(RSR)法筛选尿石症合并尿路感染(UTI)患者的经验性抗生素,为临床用药提供参考依据。方法回顾性分析2014年1月至2015年10月贵州医科大学附属医院泌尿外科收治的52例尿石症合并UTI患者的尿培养结果,利用秩和比法对主要的致病菌株进行药物敏感性分析,对临床常用抗菌药物按其敏感性的优劣进行排序分档。结果本研究结果显示尿石症患者UTI排前5位的病原菌依次为大肠埃希菌、肺炎克雷伯菌、肠球菌属、肠杆菌属、葡萄球菌属;临床常用抗菌药物按其敏感性优劣分成3档:低度敏感档:氨苄西林、头孢曲松、复方新诺明、环丙沙星、头孢呋辛、左氧氟沙星、头孢唑林;中度敏感档:庆大霉素、头孢噻肟、头孢吡肟、头孢他啶、氨苄西林-舒巴坦、头孢西丁;高度敏感档:哌拉西林-他唑巴坦、头孢哌酮-舒巴坦、亚胺培南、头孢他啶-克拉维酸、阿米卡星、呋喃妥因、美罗培南。结论尿石症患者UTI致病菌以大肠埃希菌和肺炎克雷伯杆菌为主,临床上可考虑将头孢哌酮-舒巴坦、哌拉西林-他唑巴坦等含β-内酰胺酶抑制剂的抗菌药物作为尿石症合并UTI患者经验性用药的首选。     

哌拉西林/他唑巴坦体外诱导铜绿假单胞菌释放DNA的初步研究

目的　观察不同浓度哌拉西林/他唑巴坦在体外诱导铜绿假单胞菌释放DNA的情况。方法　选择体外对铜绿假单胞菌菌株敏感的哌拉西林/他唑巴坦为本研究所用抗生素。制备铜绿假单胞菌菌液后,测定其浓度并检测哌拉西林/他唑巴坦最低抑菌浓度(MIC)和最低杀菌浓度(MBC).将不同稀释度的哌拉西林/他唑巴坦加入铜绿假单胞菌菌液中,于37℃下培养4、24h,取其上清液,采用加入SYBRGold染料的DNA电泳法检测其DNA释放情况。　结果　无论有无哌拉西林/他唑巴坦的作用,体外培养4h的铜绿假单胞菌均未测得DNA释放。无哌拉西林/他唑巴坦时,铜绿假单胞菌在体外培养24h可自发释放一定量的DNA分子,其碱基对数目分布在>2 000bp和<100bp两个区域;以第3次测定的MIC(0. 008g/L)为例,哌拉西林/他唑巴坦浓度在亚MIC(0. 002、0. 004g/L)时,诱导铜绿假单胞菌释放的DNA分子碱基对数目仍分布在上述两个区域, 但<100bp的DNA分子明显增多。哌拉西林/他唑巴坦在大于MIC时,仅诱导铜绿假单胞菌释放少量<400bp的DNA.结论　自然生长情况下铜绿假单胞菌可释放一定量的DNA分子。不同浓度的哌拉西林/他唑巴坦诱导铜绿假单胞菌释放的DNA分子,在碱基对数目和分子数量方面均有明显差别。     

Histochemical and contractile properties of striated muscles of urethra and levator ani of dogs and sheep

AIMS: To understand their possible importance in long- and short-term control of continence, some properties of the striated muscles of the urethra and pelvic floor (levator ani) of dogs and sheep were investigated, especially fiber types and contractile characteristics. MATERIALS AND METHODS: Striated muscles of urethra and levator ani of 29 male and 6 female dogs and 11 male and 6 female sheep were removed and cut into strips. Some strips were frozen and stained for ATPase at pH 9.4 and 4.3 for fiber typing; others were set up in an organ bath to study contractile responses to nerve stimulation. RESULTS: All muscles contained both type I (slow) and type II fibers, ranging from 97% type II in female greyhound urethra to 60% in female sheep levator ani. For each muscle, there were fewer type II muscles in sheep than in dog. The diameters of the urethral fibers were about 60% of the levator ani in dogs and 34% in sheep. Contraction of the urethral muscle was faster than for levator ani and declined to about 80% of the peak, 500 msec after the beginning of stimulation at 20 Hz. The levator ani contraction rose to a steady level as long as stimulation continued. CONCLUSIONS: Both the levator ani and urethral striated muscles contain slow and fast fiber types. The levator ani muscles are capable of sustained contraction with rapid onset which will produce long-term closure of the urethra. The circular urethral muscle contraction was faster but less well maintained.     

Incorporation and release of85Sr and14C-proline-hydroxyproline in mineral and collagen of bone and incisor teeth of growing rats

The extent to which exchange and reutilization processes of mineral tracers affect skeletal mineral accretion and resorption measurements was evaluated by comparing the rates of appearance and disappearance of⁸⁵Sr and¹⁴C-proline-hydroxyproline in bones and teeth in growing rats for 12 days following simultaneous parenteral injection of these tracers. Expressions for the relative rates of collagen synthesis and breakdown, which unlike mineral metabolism are considered not to be complicated by exchange phenomena, were based on¹⁴C-proline conversion to¹⁴C-hydroxyproline; the specific activity of the latter was determined. Both the mineral and the collagen specific activities reflected the rates and patterns of growth of the samples assayed; rapid growth and a short interval of time between formation and resorption of tissue in themetaphyseal bone which contains the cartilagineous growth plate, slow growth and an interval of time between formation and resorption of tissue indiaphyseal bone and incisor teeth which is longer than the 12 days of the experiment. However, in metaphyseal bone the specific activity collagen/mineral ratio dropped by one half during the 4–12 day interval in contrast to diaphyseal bone and incisor teeth in which no change in this ratio was observed during this period of time. The data indicate that collagen in the metaphyseal growth zone is removed by resorption before it has become fully mineralized, and that exchange is a relatively unimportant factor in the long term kinetics of bone mineral.

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Zusammenfassung Das Ausmaß, bis zu welchem Austausch- und Wiederverwendungsprozesse der mineralen Tracer die Messungen des mineralen Skelett-Auf- und Abbaues beeinflussen können, wurde ausgewertet; zu diesem Zweck wurde die Geschwindigkeit des Auftretens und Verschwindens von⁸⁵Sr und von¹⁴C-Prolin-Hydroxyprolin in Knochen und Zähnen von wachsenden Ratten während der 12 auf die simultane parenterale Injektion dieser Tracer folgenden Tage verglichen.Der Ausdruck für die relative Geschwindigkeit des Kollagen-Auf- und Abbaues, bei welchem im Gegensatz zum Mineralmetabolismus kein Mitwirken des Austauschphänomens vermutet wird, basiert auf der Umwandlung von¹⁴C-Prolin zu¹⁴C-Hydroxyprolin; die spezifische Aktivität des letzteren wurde bestimmt.Aus der spezifischen Aktivität des Minerals sowie jener des Kollagens konnten die Geschwindigkeit und die Art des Wachstums der untersuchten Proben ersehen werden, d.h.schnelles Wachstum und ein kurzes Zeitintervall zwischen Bildung und Resorption des Gewebes imKnochen der Metaphyse, die auch die knorpelige Wachstumsplatte enthält, und andererseitslangsames Wachstum und längeres Zeitintervall (länger als die 12 Tage des Experimentes) zwischen Bildung und Resorption des Gewebes imKnochen der Diaphyse und in den Schneidezähnen. Immerhin fiel die spezifische Aktivität des Kollagen/Mineral-Anteils im Knochen der Metaphyse während dem 4–12tägigen Zeitintervall auf die Hälfte, im Gegensatz zum Knochen der Diaphyse und der Schneidezähne, bei welchen während dieser Zeitspanne kein Unterschied in diesem Verhältnis beobachtet wurde.Diese Ergebnisse zeigen, daß Kollagen in der Wachstumszone der Metaphyse durch Resorption verschwindet, bevor es ganz mineralisiert ist, und daß der Austausch ein relativ unwichtiger Faktor in der Kinetik auf lange Sicht des Knochenminerals ist.

     

Instrumented ligamentotaxis and stabilization of compression and burst fractures of dorsolumbar and mid-lumbar spines

Background:

Controversy continues regarding the best treatment for compression and burst fractures. The axial distraction reduction utilizing the technique employing the long straight rod or curved short rod without derotation to reduce fracture are practised together with short segment posterolateral fusion (PLF). Effects of the early postoperative mobilization without posterolateral fusion on reduction maintenance and fracture consolidation were not evaluated so far. The present prospective study is designed to assess the effectiveness of i) reduction and restoration of sagittal alignment, ii) no posterolateral fusion on the reduced, fractured vertebral body and injured disc, iii) fracture consolidation and iv) the fate of the unfused cephalad and caudal injured motion segments of the fractured vertebra.

Materials and Methods:

The study includes 15 Denis burst and two Denis type D compression fractures between T₁₂ and L₃. The lordotic distraction technique was used for ligamentotaxis utilizing the contoured short rods and pedicle screw fixator. Three vertebrae including the fractured one were fixed. The patients after surgery were braced for ten weeks with activity restriction for 2-4 weeks. The patients were evaluated for change in vertebral body height, sagittal curve, reduction of retropulsion, improvement in neural deficit. The unfused motion segments, residual postoperative pain and bone and metal failure were also evaluated.

Results:

The preoperative and postreduction percentile vertebral heights at, zero (immediate postoperative), at three, six and 12 months followup were 62.4, 94.8, 94.6, 94.5 and 94.5%, respectively. The percentages of the intracanal fragment retropulsion at preoperative, and postoperative at zero, 3, 6 and 12 months followup were 59.0, 36.2,, 36.0, 32.3, and 13.6% respectively.The preoperative and postreduction percentile loss of the canal dimension and at zero, three, six and 12 months were 52.1, 45.0, 44.0, 41.0 and 29% respectively suggesting that the under-reduced fragment was being resorbed gradually by a remodeling process. The mean initial kyphosis of 33° became mean 2° immediately after reduction and mean 3° at the final followup. The fractured vertebral bodies consolidated in an average period of ten weeks (range 8-14 weeks). The restored disc heights were relatively well maintained throughout the observation period. All paraparetic patients recovered neurologically. There were no postoperative complications.

Conclusion:

Instrument-aided ligamentotaxis for compression and burst fractures utilizing the short contoured rod derotation technique and the instrumented stabilization of the fractured spine are found to be effective procedures which contribute to the fractured vertebral body consolidation without recollapse and maintain the motion segment function.     

Principles and Practice of Hemofiltration and Hemodiafiltration

There is growing interest in the convective dialysis therapies, hemofiltration (HF) and hemodiafiltration (HDF). Both require dialysis membranes which are highly permeable to solutes as well as fluid, and in both cases large volumes of ultrafiltration are the condition for convective transport. In HDF the convection is combined with diffusion, and as a consequence, maximum clearance over the entire molecular weight spectrum is achieved. Optimal forms of HDF provide urea clearance 10–15% higher than the corresponding diffusive mode. The larger the solute, the greater is the impact of convection, and β₂-microglobulin (β₂m) levels may be up to 70% reduced. Traditional postdilution HF provides high clearance of medium sized and large molecules. Satisfactory clearance of small solutes requires blood flows in excess of 500 ml/min. With access to practically unlimited volumes of substitution solution through on-line ultrafiltration, predilution HF can now be used. This increases the clearance of small solutes to an acceptable range. For HDF as well as HF, large patient populations consistently treated for longer periods of time are needed to make valid outcome comparisons with other therapies.     

骨折不愈合与延迟愈合的成因与治疗

目的探讨骨折不愈合与延迟愈合的成因、报肯治疗的方法与设果。方法对1990年7月～2004年12月间收治的107例骨折不愈台、54例骨折延迟愈合2例先天性胫骨骨不连进行回顾性研究，分析原因，随访治疗结果。18例延迟愈合行保守治疗，本组其他145例行手术治疗，结果除2例先天性胫骨骨不连外，其余161例的成因中均有医源性因素。10例失去随访，153例平均随访17（6-28）个月，骨折均获骨性连接，愈合时间平均10（6-14）个月，肢体功能恢复良好，结论医源性技术缺陷是骨折不愈合与延迟愈合的主要原因，针对各种不同因素进行合理治疗可获得满意效果。     

Recognition and management of phaeochromocytoma and paraganglioma

Phaeochromocytomas and paragangliomas (PPGL) are catecholamine-secreting neuroendocrine tumours arising from the chromaffin cells in the adrenal medulla. These tumours may be identified incidentally, as part of a work-up for multiple endocrine neoplasia or following haemodynamic surges during unrelated procedures. Advances in perioperative management and improved management of intraoperative haemodynamic instability have significantly reduced surgical mortality from around 40% to less than 3%. Surgery is the definitive treatment in most cases and laparoscopic resection where possible is associated with improved outcomes. Anaesthetic management of PPGL cases represents a unique haemodynamic challenge both before and after tumour resection. In this article we describe the physiology of these tumours, their diagnosis, preoperative optimization methods, intraoperative anaesthetic management and management of postoperative complications.     

Physiology and pharmacology of nausea and vomiting

Nausea and vomiting are both very unpleasant experiences. The physiology is poorly understood; however, understanding what we do know is key to tailoring a preventative or therapeutic antiemetic regime. There are two key sites in the central nervous system implicated in the organization of the vomiting reflex: the vomiting centre and the chemoreceptor trigger zone. There are five key neurotransmitters involved in afferent feedback to these areas. These are histamine (H₁ receptors), dopamine (D₂), serotonin (5-HT₃), acetyl choline (muscarinic) and neurokinin (substance P). Postoperative nausea and vomiting will occur in around one-third of elective patients who have no prophylaxis. This can result in many detrimental effects including patient dissatisfaction, unplanned admission and prolonged recovery. It is therefore essential that clinicians understand how they can prevent and treat nausea and vomiting using either a single agent or a combination of antiemetics to target relevant receptors. Commonly used drugs include antihistamines, dopamine antagonists, serotonin antagonists and steroids. More novel agents are being developed such as aprepitant, a neurokinin receptor antagonist, palonosetron, a 5HT₃ receptor antagonist and nabilone, a synthetic cannabinoid.     

Physiology and pharmacology of nausea and vomiting

Nausea and vomiting are both very unpleasant experiences. The physiology is poorly understood; however, understanding what we do know is key to tailoring a preventative or therapeutic antiemetic regime. There are two key sites in the central nervous system implicated in the organization of the vomiting reflex: the vomiting centre and the chemoreceptor trigger zone. There are five key neurotransmitters involved in afferent feedback to these areas. These are histamine (H₁ receptors), dopamine (D₂), serotonin (5-HT₃), acetyl choline (muscarinic) and neurokinin (substance P). Postoperative nausea and vomiting will occur in around one-third of elective patients who have no prophylaxis. This can result in many detrimental effects including patient dissatisfaction, unplanned admission and prolonged recovery. It is therefore essential that clinicians understand how they can prevent and treat nausea and vomiting using either a single agent or a combination of antiemetics to target relevant receptors. Commonly used drugs include antihistamines, dopamine antagonists, serotonin antagonists and steroids. More novel agents are being developed such as aprepitant, a neurokinin receptor antagonist, palonosetron, a 5HT₃ receptor antagonist, and nabilone, a synthetic cannabinoid.