结核分枝杆菌/利福平耐药实时荧光定量核酸扩增检测技术诊断艾滋病患者肺结核的临床应用评价

目的:探讨结核分枝杆菌(Mycobacterium tuberculosis,MTB)/利福平耐药实时荧光定量核酸扩增检测(Xpert MTB/RIF)技术诊断艾滋病患者肺结核的应用价值。方法:回顾性分析2017年7月至2019年11月上海市(复旦大学附属)公共卫生临床中心收治的226例疑似肺结核的艾滋病患者的临床资料。分别进行痰涂片荧光染色显微镜下检查、BACTEC MGIT 960液体培养(或罗氏固体培养)和Xpert MTB/RIF检测,并分析在艾滋病患者中Xpert MTB/RIF技术诊断MTB感染和利福平耐药的灵敏度和特异度。结果:226例疑似肺结核患者中,痰培养阳性94例(41.6%),其中MTB阳性51例(54.3%),非结核分枝杆菌(nontuberculosis mycobacteria,NTM)阳性43例(45.7%)。以痰分枝杆菌培养阳性且结核分枝杆菌分泌蛋白64抗原阳性为金标准,Xpert MTB/RIF技术诊断MTB的灵敏度为72.6%[95%可信区间(confidence interval,CI)66.7%~78.4%],特异度为97.1%(95%CI 95.0%~99.3%)。Xpert MTB/RIF技术诊断痰涂片阳性患者MTB的灵敏度为76.7%(95%CI 67.7%~85.8%),特异度为90.0%(95%CI 83.6%~96.5%)。Xpert MTB/RIF技术诊断痰涂片阴性患者MTB的灵敏度为50.0%(95%CI 41.8%~58.2%),特异度为99.3%(95%CI 97.9%~100.0%)。18例患者同时检测利福平表型和基因型耐药,以表型耐药为金标准,Xpert MTB/RIF技术检测利福平基因型耐药的灵敏度为75.0%,特异度为100.0%。结论:艾滋病患者中Xpert MTB/RIF技术诊断肺结核的灵敏度和特异度均较高,且能快速区分MTB和NTM,具有较好的应用价值。     

Xpert MTB/RIF技术在诊断肺结核及利福平耐药的临床价值

目的评估Xpert MTB/RIF技术在快速诊断肺结核及利福平耐药的临床应用价值。方法收集肺结核患者痰标本420例,同时进行涂片法、MGIT液体培养法(简称"液培法")+微孔板比例法药敏试验((简称"药敏法")及Xpert MTB/RIF检测结核分枝杆菌(Mtb)和利福平耐药。分别以液培法和药敏法为金标准,分析Xpert MTB/RIF检测Mtb和利福平耐药的效能,比较不同方法检测Mtb和利福平耐药的阳性检出率。结果 Xpert MTB/RIF和涂片法检测Mtb的灵敏度为84. 80%、30. 40%(P 0. 05),特异度为78. 82%、98. 82%((P 0. 05)。Xpert MTB/RIF检测利福平耐药的灵敏度为100. 00%,特异度为97. 65%。Xpert MTB/RIF检测Mtb阳性检出率为59. 05%,涂片法为18. 57%(P 0. 05),液培法为59. 52%(P 0. 05)。Xpert MTB/RIF检测利福平耐药阳性检出率为21. 70%,药敏法为19. 81%(P 0. 05)。结论与传统涂片法和液培法及药敏试验比,痰标本中Xpert MTB/RIF技术检测Mtb尤其是检测利福平耐药具有较高的敏感度、特异度,时间短,准确性高,一致性较好,对肺结核早期诊断与治疗有重要意义。     

Xpert MTB/RIF、荧光染色镜检、改良罗氏培养在肺结核实验室诊断中的应用

目的评价Xpert MTB/RIF、荧光染色镜检、改良罗氏培养在肺结核实验室诊断中的应用价值。方法收集2015年1月至2016年8月在北京市昌平区结核病防治所门诊1967例初诊被怀疑为肺结核的患者的痰标本,每例患者至少留取两份合格痰标本,实验室人员对每份痰标本均进行涂片镜检和固体培养,选择其中一份痰进行Xpert MTB/RIF检测;培养阳性菌株完成对硝基苯甲酸(P-nitrobenzoic acid,PNB)初步菌种鉴定,对鉴定为结核分枝杆菌的菌株采用比例法进行利福平药敏试验。结果 720例确诊肺结核患者中,涂片镜检、固体培养和Xpert MTB/RIF检测的灵敏度分别为18.06%(130/720)、26.94%(194/720)和36.25%(261/720)。Xpert MTB/RIF检测诊断肺结核病的灵敏度显著高于涂片镜检(χ~2=60.25,P0.01)和固体培养(χ~2=14.42,P0.01)。以比例法药敏试验结果为金标准,Xpert MTB/RIF检测利福平耐药的灵敏度和特异度分别为100%(10/10)和96.97%(160/165)。结论 Xpert MTB/RIF检测灵敏度和特异度较高,可更好的为临床肺结核病早期诊断及指导患者用药提供实验室依据。     

Xpert MTB/RIF对结核菌利福平耐药的诊断价值及rpoB基因突变特点的分析

目的分析Xpert MTB/RIF检测对结核分枝杆菌利福平耐药的诊断价值及rpoB基因突变特点。方法回顾分析2016年1月至2020年6月期间来院就诊患者相同标本,同时进行了结核分枝杆菌培养及药敏试验和Xpert MTB/RIF检测,且任一种方法检出MTB。结果用Xpert MTB/RIF及培养药敏两种方法检测标本共7659例,Xpert MTB/RIF对MTB的检出率高,且有统计学意义(P<0.05)。两种方法同时检出MTB 3621例,Xpert MTB/RIF检出利福平耐药262例,培养药敏检出利福平耐药238例;两种方法检测利福平耐药的一致率为99.01%;采用Kappa检验,两种方法的检测结果完全符合。RR-TB探针突变的频率为E探针63.37%、D探针20.16%、B探针8.23%、A探针4.53%、C探针0.82%、联合探针突变2.88%;以培养药敏结果为利福平耐药的金标准,Xpert无探针突变组利福平耐药的准确性要明显低于有探针突变组;初治和复治病例探针突变频率差异有统计学意义。结论Xpert MTB/RIF检测可以快速有效的诊断利福平耐药结核,有助于早发现、早治疗。利福平耐药结核探针突变主要发生在E探针和D探针,C探针突变最少。     

Xpert MTB/RIF检测结核分枝杆菌及其耐药性在结核病辅助诊断中的临床价值

目的探讨Xpert MTB/RIF检测方法在结核病辅助诊断中的应用价值。方法收集2013年8月至2014年3月同时对同一份标本进行结核分枝杆菌(MTB)液体培养(以下简称TB培养)和Xpert MTB/RIF实验的149例临床诊断为结核患者的资料,统计结果,并以TB培养为金标准对结果进行分析。结果149份标本中有痰液标本106份,胸水标本43份。Xpert MTB/RIF法检测结核分枝杆菌阳性率为63.8%(95/149),TB培养法检测结核分枝杆菌阳性率为51.0%(76/149),Xpert MTB/RIF检测法对痰液标本检出率为65.1%(69/106),TB培养检测法对痰液标本检出率为67.9%(72/106),Xpert MTB/RIF检测法对胸水标本检出率为60.5%(26/43),TB培养检测法对胸水标本检出率为9.3%(4/43)。结论 Xpert MTB/RIF检测法检测标本中结核分枝杆菌与TB培养法有较高一致性,Xpert MTB/RIF检测法对肺外结核的诊断可能有较高价值,在结核分枝杆菌及其对利福平耐药快速检测方面有比较好的应用前景。     

利用Xpert MTB/RIF检测结核分枝杆菌及利福平耐药性的研究

目的初步评价Xpert结核分枝杆菌/利福平(Mycobacterium tuberculosis/Rifampicin,MTB/RIF)技术对不同类型临床标本进行结核分枝杆菌及其耐药性的检测中的应用价值。方法对627例结核病患者标本分别采用Xpert MTB/RIF、涂片及培养法检测,对结果进行比较。结果 (1)经统计学分析,总体Xpert MTB/RIF法阳性率41.78%(287/627)高于涂片法阳性率24.56%(154/627),差异有统计学意义(χ~2=261.87,P0.01);Xpert MTB/RIF法阳性率高于培养法阳性率26.63%(167/627),差异有统计学意义(χ~2=249.72,P0.01);涂片法与培养法间差异无统计学意义(χ~2=20.71,P0.05)。(2)Xpert MTB/RIF和比例法药敏试验检测RFP的耐药率分别为21.43%(33/154)、20.78%(32/154),二者间差异无统计学意义(χ~2=20.02,P0.05);二种方法所得结果一致率96.75%(149/154)。结论 Xpert MTB/RIF法具有快速、简单、敏感度高、便于操作、对生物安全要求不高等优点,能同时检测出结核分枝杆菌和是否对利福平耐药,具有广泛的应用前景。     

Xpert MTB/RIF对结核性胸膜炎的诊断价值研究

目的探讨Xpert MTB/RIF对胸水中结核分枝杆菌的检出情况,评价其在结核性胸膜炎早期诊断中的应用价值。方法对102例结核性胸膜炎患者和50例恶性胸水患者的胸水进行Xpert MTB/RIF检测,同时行胸水抗酸染色及结核分枝杆菌快速培养和药敏试验(BACTECT MGIT 960),比较Xpert MTB/RIF与抗酸染色、结核分枝杆菌快速培养在敏感性及特异性上的差异,评价Xpert MTB/RIF在结核性胸膜炎诊断中的应用价值。结果 102例结核性胸水标本中,4例抗酸染色阳性,阳性率为3.92%(4/102);18例BACTECT MGIT 960培养阳性,阳性率为17.65%(18/102);24例Xpert MTB/RIF检测结核分枝杆菌阳性,阳性率为23.53%(24/102),其中,3例存在利福平耐药突变基因,耐药突变率为12.50%(3/24)。Xpert MTB/RIF检测结核分枝杆菌的阳性率高于抗酸染色法,差异有统计学意义(P0.05),与结核分枝杆菌快速培养阳性率及利福平药敏结果差异无统计学意义(P0.05)。50例恶性胸水标本抗酸染色及结核分枝杆菌快速培养均为阴性,特异性均为100%,1例Xpert MTB/RIF检测结核分枝杆菌阳性,特异性为98.00%,其特异性与抗酸染色及结核分枝杆菌快速培养差异无统计学意义(P0.05)。结论 Xpert MTB/RIF系统在结核性胸膜炎的快速诊断中具有较高的诊断能力,是一种省时、敏感性和特异性均高的结核分枝杆菌检测方法。     

Xpert MTB/RIF 检测系统对肺结核临床诊断病例的应用价值

目的 评价Xpert MTB/RIF检测系统对肺结核临床诊断病例的应用价值。方法 对296例肺结核临床诊断病例的同一痰标本分别进行BACTEC MGIT 960液体培养和Xpert MTB/RIF检测,以BACTEC MGIT 960液体培养病原学检测和药敏结果为金标准计算Xpert MTB/RIF检测系统的检验效能指标。结果 Xpert MTB/RIF检测系统与金标准存在的差异具有统计学意义 (P<0.005),其病原学诊断灵敏度为84.9%(118/139),特异度为97.5%(153/157),筛查利福平耐药的灵敏度为85.2%(23/27),特异度为100.0%(91/91),一致性检验发现两种方法在病原学诊断和利福平药敏筛检的kappa值分别为0.829和0.899。结论 Xpert MTB/RIF检测系统用于肺结核临床诊断病例的实验室诊断和利福平耐药的筛检都不同于BACTEC MGIT 960检测系统,Xpert MTB/RIF检测系统借助其较高的灵敏度和特异度、快速和操作方便的优势,值得在中国结核病实验室推广应用。     

InnowaveDX MTB/RIF对结核分枝杆菌复合群及利福平耐药检测性能评估

目的评估结核分枝杆菌(MTB)和利福平耐药突变检测试剂盒(InnowaveDX MTB/RIF, 简称InnowaveDX)检测痰液对MTB复合群及利福平耐药的诊断价值。方法前瞻性连续纳入2020年6月19日至2022年5月16日湖南省结核病防治所、河南省传染病医院和武汉市金银潭医院就诊的具有结核病体征的患者1 328例, 依据纳入及排除标准, 最终纳入1 035例肺结核患者(确诊患者357例, 临床诊断患者678例)和180例非结核患者。收集所有患者的痰液样本, 进行常规痰涂片、痰培养、药敏试验, 并评价Xpert?MTB/RIF(简称Xpert)和InnowaveDX对肺结核和利福平耐药的诊断价值。对肺结核的诊断分别以临床诊断和MTB培养结果为参考标准, 对利福平耐药的评价分别以表型药敏试验和Xpert为参考标准, 分析两种检测方法对结核病诊断和利福平耐药的敏感度、特异度、阳性预测值、阴性预测值。两种检测技术的一致性分析行kappa检验。结果以临床诊断为参考标准, InnowaveDX对1 035例临床诊断肺结核患者检测敏感度[58.0%(600/1 035)]高于Xpert[51...     

结核病诊断T-SPOT.TB、Gene Xpert MTB/RIF技术应用价值研究北大核心CSCD

目的评估结核分枝杆菌及其利福平耐药株实时荧光定量核酸扩增(Gene Xpert MTB/RIF)和结核感染T细胞斑点试验(T-SPOT.TB)在结核病诊断中的价值。方法分析2020年1月-2022年3月济宁市公共卫生医疗中心收治的住院及门诊病患者643病例的抗酸染色镜检、960液体培养、Gene Xpert MTB/RIF检测和结核抗体、T-SPOT.TB检测结果,评价Gene XpertMTB/RIF和T-SPOT.TB检测诊断结核病的特点和价值,以临床诊断为金标准,以检测方法的敏感度、特异度及绘制的ROC曲线等作为评价指标。结果抗酸染色、960快速培养和Gene Xpert MTB/RIF检测结核病的敏感度分别为21.57%、39.21%和59.80%,特异度分别为100.00%、97.22%和100.00%。ROC曲线分析显示,抗酸染色、960结核菌培养和Gene XpertMTB/RIF的AUC分别是0.60、0.70和0.80,差异有统计学意义(P<0.05);95%置信区间范围分别为0.50~0.70,0.61~0.78,0.73~0.87。T-SPOT.TB和结核抗体检测的敏感度分别为84.61%和70.19%,特异度分别为95.83%和79.16%。ROC曲线分析结核抗体与TSPOT检测的AUC分别为0.75和0.90,95%,置信区间范围分别为0.64~0.86和0.84~0.97。T-SPOT.TB和Gene Xpert MTB/RIF的阳性率分别为86.47%和36.60%。结论在结核病诊断中,Gene Xpert MTB/RIF和T-SPOT.TB检测结核病的敏感性高于痰涂片和痰培养检查及结核抗体检测,其中T-SPOT.TB检测的阳性率较高。Gene Xpert MTB/RIF和T-SPOT.TB均可应用于肺结核的临床诊断以提高肺结核的诊治效率。     

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。     

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。     

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。     

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.