阻塞性睡眠呼吸暂停低通气综合征患者呼吸阻抗值变化的意义

目的探讨阻塞性睡眠呼吸暂停低通气综合征(OSAHS)患者呼吸阻抗值的变化及临床意义。方法用脉冲振荡技术检测38例OSAHS患者、28例COPD患者和20例健康人的呼吸阻抗值,同时进行多导睡眠图监测。结果 OSAHS患者上气道阻力(R35)、中心气道阻力(R20)明显高于COPD组和对照组,差异有统计学意义(P均<0.05);且共振频率、呼吸总阻抗(Zrs)、中心阻力、R20、R35随OSAHS病情加重呈升高趋势,各组之间差别有统计学意义(P均<0.05);OSAHS患者R35、R20与呼吸暂停低通气指数(AHI)呈正相关(r分别为0.623、0.617,P均<0.05);R35、R20、Zrs与最低指端血氧饱和度呈负相关(r分别为-0.607、-0.591和-0.462,P均<0.05)。结论 OSAHS患者上气道阻力及中心气道阻力升高,且此改变与OSAHS病情严重程度相关。     

OSAHS患者咽部解剖与呼吸驱动的关系研究

目的 探讨OSAHS患者咽腔形态与呼吸驱动(p0.1)的关系.方法 随机选取OSAHS患者35例,进行仰卧位睡眠状态下呼吸驱动测定及螺旋CT扫描,针对轻度(AHI ＜20)、中重度(AHI＞ 20)两组患者进行研究.结果 睡眠状态下,①中重度组软腭长度,软腭厚度,颏舌肌宽度及舌体面积明显增加(P＜0.05),软腭后区最小气道面积明显减小(P＜0.05);②中重度组P0.1的下降更为明显(P＜0.05).③中重度组颏舌肌宽度与P0.1有明显负相关性(r=-0.574,P＜0.05).结论 睡眠状态下,咽腔狭窄程度与OSAHS病情相关,随着OSAHS患者病情加重,颏舌肌的代偿作用增加,当代偿到一定程度时出现呼吸驱动的降低.     

阻塞性睡眠呼吸暂停低通气综合征患者日间气道阻力的研究

目的 研究阻塞性睡眠呼吸暂停低通气综合征(obstructive sleep apnea-hypopnea syndrome,OSAHS)患者清醒时气道阻力的改变及气道阻力对睡眠呼吸暂停低通气指数(apneahypopnea index,AHI)变异所起的作用.方法 选取2011年10月至2012年5月因打鼾及夜间憋醒等就诊于天津医科大学总医院呼吸科睡眠实验室的阻塞性睡眠呼吸暂停低通气患者95例,选取同时段无夜间打鼾及日间嗜睡等症状且年龄及体质量指数等与OSAHS组相匹配的健康体检者20名为对照组.采用脉冲震荡法对OSAHS组及正常对照组患者行气道阻力的测定.结果 OSAHS组与正常对照组相比,振荡频率为5Hz时的黏性阻力(respiratory resistance at 5 Hz,R5)、振荡频率为10 Hz时的黏性阻力(respiratory resistance at 10 Hz,R10)、振荡频率为15 Hz时的黏性阻力(respiratory resistance at 15 Hz,R15)、振荡频率为20 Hz时的黏性阻力(respiratory resistance at 20 Hz,R20)、振荡频率为25 Hz时的黏性阻力(respiratory resistance at 25 Hz,R25)、振荡频率为35 Hz时的黏性阻力(respiratory resistance at 35 Hz,R35)显著增高,差异有统计学意义(P＜0.05);重度OSAHS患者与轻度OSAHS患者相比,各指标间虽差异无统计学意义(P＞0.05),但各指标有增大的趋势.线性回归分析显示AHI与R5、R10、R15、R20、R25、R35显著相关(r值分别为0.328、0.304、0.282、0.267、0.289、0.295).以AHI为因变量,R5、R10、R15、R20、R25、R35为自变量进行多元逐步回归分析显示R5对AHI的变异所起的作用为12.1％.结论 阻塞性睡眠呼吸暂停低通气患者的日间气道阻力显著增加,并且随着阻塞性睡眠呼吸暂停低通气的严重程度增加气道阻力也增加,R5是阻塞性睡眠呼吸暂停低通气的预测因子,日间气道阻力增加对AHI的变异起着重要的作用.     

体位对急性脑梗死患者睡眠呼吸紊乱的影响

目的探讨睡眠体位对脑梗死患者睡眠呼吸紊乱的影响和作用机制。方法选择急性脑梗死患者53例,分为睡眠呼吸暂停综合征(SAHS)组34例,非SAHS组19例。采用视频多导睡眠监测仪,对急性脑梗死患者自然睡眠过程及不同体位睡眠呼吸状况进行全程描记。结果 53例患者中,有34例(64.2%)急性脑梗死患者睡眠呼吸暂停低通气指数(AHI)≥10。与仰卧位比较,SAHS组左、右侧卧位患者的AHI明显降低,平均血氧饱和度明显升高(P<0.05,P<0.01);且睡眠呼吸紊乱事件以阻塞型为主,仰卧位最重(P<0.01);SAHS组患者自然睡眠状态下,AHI与侧卧位/仰卧位睡眠时间比值呈负相关(r=-0.56,P<0.01)。结论脑梗死后睡眠呼吸紊乱发生率高,仰卧位时加重,体位自我调节保护睡眠呼吸的功能减弱。     

脉冲振荡法测定在COPD患者中的应用研究

目的探讨脉冲振荡法(IOS)测定在慢性阻塞性肺疾病(COPD)患者中的临床应用。方法选择100例COPD患者(COPD组)和50例健康体检者(对照组),比较二者常规肺功能检测及IOS检测结果,并分析两种方法的相关性。结果与对照组比较,COPD组用力肺活量(FVC),第1s用力呼气容积(FEV1)、第1 s用力呼气容积/用力肺活量百分比(FEV1/FVC%)、FEV1实测值/预计值(FEV1/Pre%)均显著降低(P0.05);COPD组共振频率(Fres)、呼吸总阻抗(Zrs)、5 Hz时呼吸总阻抗(Z5)、5 Hz时电抗(X5)、总气道阻力(R5)、中心气道阻力(R20)、周边气道阻力(R5-R20)、中心阻力(Rc)及周边阻力(Rp)均较对照组显著升高(P0.05);Fres、R5、R20、R5-R20与FEV1、FEV1/FVC%、FEV1/Pre%均呈显著负相关(P0.05)。结论 IOS测定可较好地反映COPD患者气道阻力的变化,联合常规肺功能测定可更好地判断COPD患者的气道堵塞及病情变化,尤其适用于老年患者。     

冠心病合并OSAHS患者夜间心律失常情况分析

目的 进一步分析冠心病合并阻塞性睡眠呼吸暂停综合征(OSAHS)患者夜间心律失常情况,并探讨其形成机制.方法 120例冠心病患者按睡眠呼吸监测结果合并OSAHS者90例(OSAHS组),不合并OSAHS者30例(非OSAHS组).对两组临床资料及夜间心律情况进行比较.结果 两组夜间最慢心率和平均心率变化有明显异常(P＜0.05);OSAHS组夜间窦性心动过速、室性心律失常以及传导阻滞的发生率明显高于非OSAHS组(P＜0.05);窦性心动过缓和心房颤动的发生率亦明显高于非OSAHS组(P＜0.01).结论 冠心病合并OSAHS患者夜间心律失常发生率明显增高,尤其是窦性心动过缓和心房颤动发生率显著升高.     

脉冲震荡法对慢性阻塞性肺疾病严重程度评估的临床意义

目的 通过对COPD稳定期患者进行脉冲震荡法(IOS)及常规肺功能FEV1％pred和FEV1/FVC测定,探讨IOS对COPD严重程度评估的临床意义.方法 收集2014年7月至2015年6月于山西大医院确诊为COPD稳定期的患者214例,根据GOLD(2011版)联合评估的方法将其分为A、B、C和D4组.选同期体检人员41例作为健康对照组,分别进行IOS(Z5、R5、R20、R5-R20、X5、Fres)及常规肺功能(FEV1％pred、FEV1/FVC)检测.结果 ①COPD组男164例,女50例,平均年龄(63.6±9.5)岁;其中A组48例、B组68例、C组55例、D组43例.健康对照组男26例,女15例,平均年龄(54.6±10.4)岁.2组性别及平均年龄差异无统计学意义.②COPD组IOS中Z5、R5、R20和R5-R20分别为(0.70±0.30)、(0.62±0.25)、(0.36±0.12)和(0.26±0.18) kPa·L-1·s-1,Fres为(28.71±9.07) Hz及常规肺功能中FEV1％ pred和FEV1/FVC分别为(50.83±21.91)％和(51.57±11.29)％均较健康对照组显著增高(P值均＜0.05).X5为(-0.31±0.19) kPa·L-1·s-1,较健康对照组显著减低(P＜0.05).③COPD患者A、B、C和D4组IOS中Z5、R5、R5-R20和Fres呈上升趋势,X5呈下降趋势.A、B、C3组间比较差异均有统计学意义(P值均＜0.05).④COPD患者IOS中Z5、R5、R5-R20和Fres与FEV1％pred均呈显著负相关(P值均＜0.05),其中Fres与FEV1％pred相关性最大(r=-0.599);X5与FEV1％pred呈显著正相关(P＜0.05).COPD患者A、B、C和D4组IOS中各指标与FEV1％pred相关性逐渐降低.A、B、C3组间比较差异均有统计学意义(P值均＜0.05).结论 IOS测定能较好地反映不同组别COPD患者气道阻力的变化,可更好地评估COPD患者疾病严重程度,尤其适用于老年患者.     

老年哮喘和慢性阻塞性肺疾病患者的呼吸阻抗

目的 探讨呼吸阻抗在老年哮喘和慢性阻塞性肺疾病( COPD)患者中的应用价值.方法 选取老年哮喘患者88例(哮喘组)、COPD患者276例(COPD组)和健康体检者45名(对照组),采用肺量计法检测常规通气功能、脉冲震荡法(IOS)进行呼吸阻抗测定,并分析通气功能FEV1/FVC和FEV1占预计值百分比与呼吸阻抗的相关性.结果 与对照组比较,哮喘组20 Hz时气道阻力(R20)增高(P＜0.05),COPD组呼吸总阻抗(Zrs)、5 Hz时气道阻力(R5)明显增加(P＜0.01,P＜0.05);哮喘组和COPD组5 Hz与20Hz时气道阻力差值(R5 -R20)、中心阻力(Rc)、周边阻力(Rp)及共振频率(Fres)均明显增高,5 Hz时电抗(X5)明显下降(P＜0.05或P＜0.01);与哮喘组比较,COPD组R5-R20、Rp、Fres增加,X5下降(P ＜0.05或P＜0.01);随COPD严重程度加重,Zrs、R5、R5 - R20、Rc、Rp、Fres逐渐增加,X5逐渐下降(P＜0.05或P＜0.01).哮喘组与COPD组FEV1/FVC和FEV1占预计值百分比与气道阻力Zrs、R5、R5 - R20均呈负相关(P＜0.05或P＜0.01),而与X5呈正相关(P＜0.01);哮喘组FEV1/FVC和FEV1占预计值百分比与R20均呈负相关(P＜0.01),而COPD组FEV1/FVC和FEV1占预计值百分比与R20无相关性(均P＜0.05);哮喘组FEV1占预计值百分比与Fres呈负相关(P＜0.01),FEV1/FVC与Fres无相关性(P＜0.05),COPD组FEV1/FVC和FEV1占预计值百分比与Fres均呈负相关(P＜0.01).结论 哮喘和COPD两组患者的气道阻力均增加,但增加的部位不同,哮喘患者以中心气道阻力增加为主.COPD患者以外周气道阻力增加为主;COPD患者呼吸总阻抗明显增加,且与COPD患者病情严重程度有关,中重度COPD明显增加.呼吸阻抗与通气功能具有良好的相关性,提示简单易行的呼吸阻抗测定具有较好的临床应用前景.     

脉冲振荡肺功能测定在稳定期慢性阻塞性肺疾病治疗中的应用价值

目的探讨脉冲振荡肺功能测定(IOS)在稳定期慢性阻塞性肺疾病(COPD)临床治疗中的应用价值,及与传统肺功能检测的相关性。方法收集2013年1月至2015年12月我院呼吸科住院的稳定期COPD患者100例作为实验组,根据COPD严重程度分为A、B、C、D四组,A组(轻度)17例,B组(中度)21例,C组(重度)33例,D组(极重度)29例,另选40例健康人作为对照组。所有研究对象入组后进行IOS肺功能测定(Zrs、Fres、R5、R20、X5)和传统肺功能测定(FEV_1、FEV_1/FVC),COPD患者治疗三个月后复诊。结果治疗前后,实验各组与健康组比较,FEV_1、FEV_1/FVC、X5显著降低,Zrs、Fres、R5、R5-R20、R20显著升高;并且COPD越严重Zrs、Fres、R5、R5-R20、R20越高,FEV_1、FEV_1/FVC、X5越低(P0.05);经过治疗后,四个实验组FEV_1、FEV_1/FVC显著升高,Zrs、Fres、R5、R5-R20显著降低(P0.05),X5、R20无明显改变。FEV_1、FEV_1/FVC与Zrs、Fres、R5、R5-R20呈明显负相关(P0.05),与X5呈明显正相关(P0.05),其中FEV_1与Fres的相关性最强(r=-0.765)。结论 IOS肺功能检测指标能客观反映气道阻力,并且与传统肺功能指标有良好的相关性,可以作为一种新的COPD诊断技术在临床上推广使用。     

脉冲振荡法在阻塞性通气功能障碍中的应用

目的 使用脉冲振荡法(IOS)测定慢性阻塞性肺疾病(COPD)患者的呼吸阻抗,探讨呼吸阻抗与气流阻塞及肺容积之间的关系.方法 用IOS法测定200例COPD患者及100例正常受试者(健康组)(年龄≥60岁)的R5、R20、共振频率(Fres)、X5、RC和周边阻力(RP)的实测值,常规肺功能测定肺总量(TLC)、残气量(RV)、第1秒用力呼气量(FEV1)、用力肺活量(FVC)及FEV1/FVC等指标.结果 与健康组相比,COPD组R5、R20、R5-R20、Fres、RC和RP均显著升高,X5显著降低(均P＜0.01);R5、R5-R20、RP、Fres都与FEV1％、FEV1/FVC呈负相关;X5与FEV1％、FEV1/FVC均呈正相关(P＜0.01);R20与其中任何一项指标均无相关性;其中相关性最强的是FEV1％与X5(r=0.419),FEV1％与Fres(r=-0.553).Fres、X5和R5诊断气流阻塞的阳性率分别为99.9％,94.5％,49.0％.结论 在COPD所致的气流阻塞及肺顺应性改变中,IOS电抗测定比阻力测定更具敏感性.IOS的测定指标可用于评估阻塞性通气功能障碍,尤其是X5的诊断价值最大,并且与常规肺通气功能指标之间有良好的相关性.     

胰岛素瘤的解剖分布特点分析

目的胰岛素瘤是最常见的胰腺神经内分泌肿瘤，因其临床表现多样，导致诊断困难。影像学诊断尤其是超声内镜(EUS)在胰岛素瘤的诊断中起着重要作用，拥有较高的敏感性和特异性。本研究拟通过明确胰岛素瘤的解剖分布特点，以期有助于提高影像学的诊断准确率和降低漏诊率，尤其是在教育和培训实践中对于EUS的学习者更具有指导价值。 方法回顾性分析解放军总医院第一医学中心病案资料数据库1993年1月至2019年11月经外科手术、病理确诊为胰岛素瘤的患者的临床资料，检索方法采取搜索术后病理诊断为"胰岛素瘤"的病例，通过查阅病例的方法，提取出胰岛素瘤的大小和解剖分布等数据，进一步分析其特点。 结果共检索到确诊为胰岛素瘤的患者116例，其中，男45例、女71例，年龄13～76岁，平均年龄(44.4±14.85)岁。胰岛素瘤单发110例(94.8%)、多发6例(5.2%)。位置分布：头颈部46例(39.7%)，单发45例、多发1例；体尾部68例(58.6%)，单发65例、多发3例；全胰腺多发2例(1.7%)。病变大小特点：最大径0.4～3.4 cm，平均大小(1.53±0.58)cm。≤1 cm 29例、>1 cm而≤1.5 cm41例、>1.5 cm而≤2.0 cm28例，≤3 cm 15例，>3 cm 3例。年龄与肿瘤的大小相关，≤44岁患者肿瘤平均大小为(1.36±0.51)cm、>44岁患者肿瘤平均大小为(1.70±0.60)cm，P<0.05。头颈部的肿瘤大于体尾部的肿瘤，头颈部肿瘤平均大小(1.66±0.63)cm，体尾部(1.42±0.52)cm，P<0.05。 结论胰岛素瘤在胰腺体尾部较头颈部更好发；绝大多数单发，但可以全胰腺多发；多数小于1.5 cm，肿瘤的大小与患者年龄和肿瘤的解剖分布相关。     

Pathogenesis of carcinoma of the papilla of Vater

Most adenomas and carcinomas of the small intestine and extrahepatic bile ducts arise in the region of the papilla of Vater. In familial adenomatous polyposis (FAP) it is the main location for carcinomas after proctocolectomy. In many cases symptoms due to stenosis lead to diagnosis at an early tumor stage. In about 80%, curative intended resection is possible. Operability is the most relevant prognostic factor. Most ampullary carcinomas resp. carcinomas of the papilla of Vater develop from adenomatous or flat dysplastic precursor lesions. They can be sited in the ampulloduodenal part of the papilla of Vater, which is lined by intestinal mucosa. They also can develop in deeper parts of the ampulla, which are lined by pancreaticobiliary duct mucosa. Intestinal-type adenocarcinoma and pancreaticobiliary-type adenocarcinoma represent the main histological types of ampullary carcinoma. Furthermore, there exist unusual types and undifferentiated carcinomas. Many carcinomas of intestinal type express the immunohistochemical marker profile of intestinal mucosa (keratin 7?, keratin 20+, MUC2+). Carcinomas of pancreaticobiliary type usually show the immunohistochemical profile of pancreaticobiliary duct mucosa (keratin 7+, keratin 20?, MUC2?). Even poorly differentiated carcinomas, as well as unusual histological types, may conserve the marker profile of the mucosa they developed from. These findings underline the concept of histogenetically different carcinomas of the papilla of Vater which develop either from intestinal- or from pancreaticobiliary-type mucosa of the papilla of Vater. Molecular alterations in ampullary carcinomas are similar to those of colorectal as well as pancreatic carcinomas, although they appear at different frequencies. In future studies, molecular alterations in ampullary carcinomas should be correlated closely with the different histologic tumor types. Consequently, the histologic classification should reflect the histogenesis of ampullary tumors from the two different types of papillary mucosa.     

Demonstration of the mechanism of action of biguanides

Summary Palmitic acid oxidation in rat diaphragm homogenate is depressed by biguanide concentrations that are still incapable of inhibiting oxidative phosphorylation. Glucose oxidation is not directly effected by the same biguanide concentrations: however, the inhibitory effect of palmitic acid on glucose oxidation is partly removed by biguanides. Inhibition of fatty acid oxidation, which accounts for most of the metabolic effects caused by these drugs, can be regarded as the fundamental mechanism of action of biguanides. There is some evidence suggesting that these drugs might interact with carnitine, thus preventing long-chain fatty acids from being transported across the mitochondrial membrane to the site of oxidation. Traduzione a cura degli AA.     

Lack of correlation of degree of villous atrophy with severity of clinical presentation of coeliac disease

BACKGROUND AND AIM: Both the clinical presentation and the degree of mucosal damage in coeliac disease vary greatly. In view of conflicting information as to whether the mode of presentation correlates with the degree of villous atrophy, we reviewed a large cohort of patients with coeliac disease. PATIENTS AND METHODS: We correlated mode of presentation (classical, diarrhoea predominant or atypical/silent) with histology of duodenal biopsies and examined their trends over time. RESULTS: The cohort consisted of 499 adults, mean age 44.1 years, 68% females. The majority had silent coeliac disease (56%) and total villous atrophy (65%). There was no correlation of mode of presentation with the degree of villous atrophy (p=0.25). Sixty-eight percent of females and 58% of males had a severe villous atrophy (p=0.052). There was a significant trend over time for a greater proportion of patients presenting as atypical/silent coeliac disease and having partial villous atrophy, though the majority still had total villous atrophy. CONCLUSIONS: Among our patients the degree of villous atrophy in duodenal biopsies did not correlate with the mode of presentation, indicating that factors other than the degree of villous atrophy must account for diarrhoea in coeliac disease.     

血吸虫童虫生长发育及其机制的研究进展

血吸虫童虫是宿主免疫系统攻击的重要靶标,包括皮肤型、肺型和肝门型童虫。宿主分子对童虫生长发育具有重要作用。童虫生长发育机制包括免疫调节、信号转导、性别发育及凋亡等。肌动蛋白、组织蛋白酶、烯醇化酶和葡萄糖基转移酶等分子为血吸虫童虫生长发育的重要分子。本文对血吸虫童虫生长发育及其机制的研究进展做一综述。     

氯硝柳胺悬浮剂的毒性评价

目的评价氯硝柳胺悬浮剂的毒性，为现场大规模应用灭螺提供依据。方法按照中华人民共和国国家标准GB 15670-1995《农药登记毒理学试验方法》和鱼类毒性试验方法进行。结果经口、经皮肤的LDso雌、雄性大鼠均>5 000 mg/kg，经呼吸道的LCso雌、雄性大鼠均>5 000mg/m3，该药经口、经皮肤、经呼吸道毒性均属微毒类药物；兔眼用药后，观察期内无不良反应，对眼无刺激性；皮肤用药后对皮肤无刺激性。与氯硝柳胺原药、氯硝柳胺乙醇胺盐原药和氯硝柳胺乙醇胺盐可湿性粉剂相比，氯硝柳胺悬浮剂对鱼急性毒性最低。结论氯硝柳胺悬浮剂属微毒类药物，对鱼的毒性低于其乙醇胺盐可湿性粉剂，适合于现场应用。     

124例耐多药结核分枝杆菌基因突变特征分析

目的对临床分离的耐多药结核分枝杆菌相关基因的突变特征进行分析。方法对124例耐多药结核分枝杆菌以及50株敏感株的耐药相关基因(包括异烟肼inh A、kat G、oxyR-ahp C间隔区以及利福平rpo B)进行序列测定,分析其基因突变情况。结果异烟肼耐药inh A基因突变率为14.5%;kat G基因突变率为70.2%(87/124),主要位于315位;oxyR-ahp C间隔区突变率为15.3%;inh A、kat G两种基因同时突变率75.0%,三种基因同时突变率为89.5%。利福平rpo B基因突变的检出率高达95.2%,突变主要发生在531、526、516位点。结论我省耐多药菌异烟肼耐药相关基因最常见突变为kat G 315、inh A C-T(-15)、axyR-ahp C间隔区(-10)C-T,利福平为rpo B531、526、516。结合MDR-TB耐药相关基因的特征分析,可以建立一种快速、准确、特异的适合于我省的检测结核菌耐多药性的新方法。     

Assessment of quality of life of parents of children with juvenile chronic arthritis

The aim of the study was to assess the quality of life (QOL) and the psychological status of parents of children with juvenile chronic arthritis (JCA). The QOL, anxiety and depression of the parents of 28 children with JCA were evaluated and compared to those of the parents of 28 healthy children. Mothers of JCA children and mothers of healthy children reported similar QOL. The reported anxiety and depression levels were similar for mothers and fathers in both groups. The parents of children with pauciarticular-type JCA reported lower QOL and higher levels of anxiety and depression than the parents of children with other types, namely polyarticular and systemic JCA. These findings may be explained by the fact that the pauciarticular patients had shorter disease duration and were less frequently seen in the outpatient clinic. The QOL of mothers of children with JCA was found to be slightly impaired in the group of children with pauciarticular JCA. Future larger studies are needed to confirm these results, as the number of subjects in the three groups was rather low. Received: 26 September 2001 / Accepted: 8 February 2002     

Numerical Simulation of the Effect of Rate of Change of Glucose on Measurement Error of Continuous Glucose Monitors

Background

A 5-day in-patient study designed to assess the accuracy of the FreeStyle Navigator® Continuous Glucose Monitoring System revealed that the level of accuracy of the continuous sensor measurements was dependent on the rate of glucose change. When the absolute rate of change was less than 1 mg•dl⁻¹•min⁻¹ (75% of the time), the median absolute relative difference (ARD) was 8.5%, with 85% of all points falling within the A zone of the Clarke error grid. When the absolute rate of change was greater than 2 mg•dl⁻¹•min⁻¹ (8% of the time), the median ARD was 17.5%, with 59% of all points falling within the Clarke A zone.

Method

Numerical simulations were performed to investigate effects of the rate of change of glucose on sensor measurement error. This approach enabled physiologically relevant distributions of glucose values to be reordered to explore the effect of different glucose rate-of-change distributions on apparent sensor accuracy.

Results

The physiological lag between blood and interstitial fluid glucose levels is sufficient to account for the observed difference in sensor accuracy between periods of stable glucose and periods of rapidly changing glucose.

Conclusions

The role of physiological lag on the apparent decrease in sensor accuracy at high glucose rates of change has implications for clinical study design, regulatory review of continuous glucose sensors, and development of performance standards for this new technology. This work demonstrates the difficulty in comparing accuracy measures between different clinical studies and highlights the need for studies to include both relevant glucose distributions and relevant glucose rate-of-change distributions.     

Study of constancy of hydrogen-consuming flora of human colon

The constancy of the hydrogen consuming flora of the human colon was studied in 15 healthy subjects via two measurements obtained 18 to 36 months apart. Hydrogen disappearance rate and the major products of H₂-consuming bacteria, methane and sulfide, were measured during incubation of fecal homogenates with excess hydrogen and sulfate. In 11/15, the hydrogen consumption rate and the predominant hydrogen-consuming pathway (methanogenesis, sulfate reduction, or neither) remained constant. However, major shifts in these pathways were observed in four subjects, with two losing and two gaining the ability to produce methane. Methanogenesis was associated with the highest hydrogen consumption rate. This study demonstrates that clinically unrecognizable, major alterations of the colonic flora occur in healthy subjects. Understanding of the factors responsible for these alterations might allow for therapeutic manipulation of the colonic flora.Supported in part by the Department of Veterans Affairs and NIDDKD RO1 DK 13309-25.