胃扩张对大鼠脑、脊髓和肌间神经丛Fos蛋白和降钙素基因相关肽表达的影响

背景:功能性消化不良是一种常见疾病,越来越多的证据显示其发病与内脏神经敏感性增高有关。目的:通过测定大鼠伤害性胃扩张后脑、脊髓和肌间神经丛Fos蛋白和降钙素基因相关肽(CGRP)的表达,探索内脏刺激传入的途径和方式。方法:24只成年Sprague-Dawley雄性大鼠随机分为3组:实验组(12只)、手术对照组(6只)和空白对照组(6只)。实验组和手术对照组先植入胃内气囊。48h后,实验组接受反复的气囊扩张[80mmHg(1mmHg=0.133kPa)],2h后处死全部实验动物,立即取材。采用免疫组化法观察脑、脊髓和肌间神经丛Fos蛋白和CGRP的表达。结果:实验组杏仁核、延髓和胸髓Fos蛋白的表达较其他两组显著增强(P均<0.01),肌间神经丛的Fos蛋白表达3组间无显著差异。实验组延髓、胸髓CGRP表达较其他两组显著增强(P<0.05和P<0.01)。延髓和胸髓中Fos蛋白与CGRP的表达显著相关(rs分别为0.794和0.728,P均<0.01)。结论:胃扩张刺激可以兴奋皮层下中枢,CGRP在内脏刺激信号的传入过程中起重要作用。     

大鼠结肠慢性炎性刺激诱导腰骶髓和延髓Fos的表达及其意义

目的　探讨实验性大鼠结肠慢性炎性刺激诱导腰骶髓和延髓中Fos的表达及其意义。方法　成年雄性SD大鼠 ,实验组 (n =1 6 )予三硝基苯磺酸 (TNBS)灌肠诱导结肠炎 ,实验对照组 (n =8)予生理盐水灌肠 ,空白对照组 (n =2 )不予任何刺激 ;分别在灌肠后 3、7、1 4和 2 8d ,采用免疫组化法观察实验组大鼠腰骶髓和延髓中Fos阳性神经元的数量和分布 ,并与对照组进行比较。结果　TNBS灌肠诱导Fos表达多数分布在脊髓背角深层 (Ⅲ～Ⅳ和Ⅴ～Ⅵ层 )和由孤束核、腹外侧区及网状结构形成的延髓内脏带中。TNBS灌肠后 3d ,脊髓和延髓中Fos表达无明显增多。灌肠后 7和 1 4d ,脊髓和延髓中Fos表达明显多于实验对照组 (P <0 .0 5 )。灌肠后 2 8d ,延髓中Fos表达下降 ,与对照组无明显差异 ,部分大鼠脊髓中Fos阳性神经元数 (5 4 .1± 1 6 .3)仍明显多于对照组 (1 2 .2± 2 .6 ,P <0 .0 5 )。结论　脊髓Fos阳性神经元可能在结肠慢性炎性刺激引起的内脏高敏感性中起作用 ,而延髓可能不是内脏高敏感性形成的主要部位。     

替加色罗对内脏高敏性大鼠直肠扩张后脊髓c-Fos表达的影响

目的　研究替加色罗对大鼠内脏敏感性的作用。方法　新生SD大鼠出生后第 8至 2 1天予醋酸灌肠 ,建立慢性内脏高敏模型为H组 ;生理盐水灌肠为C组。待大鼠成年后 ,将H组分为H病理 、H盐水 、H溶剂 、HTeg0 .1、HTeg0 .3 和HTeg1.0 组 ;C组分为C病理 、C盐水 和CTeg1.0 组。H病理 和C病理 组不扩张直肠行病理学检查和髓过氧化物酶活性测定 ;H盐水 和C盐水 组腹腔注射生理盐水 ,H溶剂 组注射溶剂 蒸馏水 ,HTeg0 .1、HTeg0 .3 和HTeg1.0 组分别注射替加色罗 0 .1、0 .3、1.0mg/kg ,CTeg1.0 组注射替加色罗 1.0mg/kg ,直肠球囊快速注水 (0 .4、0 .8、1.2ml)扩张观肠道 ,每次扩张持续 2 0s,间隔 5min ,察腹部撤离反射 (AWR)和脊髓 (L6～S1)c Fos表达。结果　H盐水 与H溶剂 组AWR积分明显高于其他组 (P <0 .0 5 ) ,腰骶髓c Fos阳性细胞总数明显增加 ,两组间无明显差异。HTeg0 .1、HTeg0 .3 和HTeg1.0 组比H盐水 组AWR积分明显降低 ,c Fos阳性细胞减少 (182± 14 ,16 6± 17,12 8± 15比 2 13± 13;P <0 .0 5 )。结论　替加色罗可明显降低内脏高敏大鼠的内脏敏感性 ,并剂量依赖性地减少脊髓c Fos的表达     

替加色罗对糖尿病大鼠胃排空功能及Ghrelin、P物质表达的影响

目的:研究替加色罗对糖尿病大鼠胃排空功能及胃组织Ghrelin、P物质表达的影响,探讨替加色罗对糖尿病胃轻瘫的治疗作用及其可能的机制.方法:50只清洁级♂Wistar大鼠随机分为正常对照组(NC组,n=10)、糖尿病组(DM组,n=10)、低剂量替加色罗治疗组(TEG-L组,n=10)、中剂量替加色罗治疗组(TEG-M组,n=10)和高剂量替加色罗治疗组(TEG-H组,n=10).ip链脲佐菌素(STZ)制备糖尿病大鼠模型,8 wk后分别以0.1,0.5和1 mg/kg的剂量给予TEG-L,M和H组大鼠ip替加色罗连续3 d,采用酚红灌胃法检测胃排空,免疫组化技术检测各组大鼠胃黏膜Ghrelin与胃窦组织SP的表达.结果:TEG各组大鼠Ghrelin(34.721±6.759,33.547±6.255,35.141±5.987)与SP的积分光密度(13.548±1.078,13.952±1.246,11.845±1.567)均低于NC组(Ghrelin:43.514±5.323,P<0.05,P<0.01,P<0.01;SP:16.383±2.275,均P<0.01)而高于DM组(Ghrelin:26.626±4.596,均P<0.05;SP:9.257±1.636,均P<0.01);Ghrelin积分光密度在TEG各组之间无显著性差异,而TEG-L,M组SP积分光密度均高于TEG-H组(均P<0.05).结论:替加色罗可通过促进胃组织Ghrelin与SP的表达释放来改善糖尿病大鼠延迟的胃排空.     

粪菌移植对DSS诱导的结肠炎小鼠内脏敏感性的影响

背景:粪菌移植(FMT)能减轻炎症性肠病(IBD)患者肠黏膜炎症、改善临床症状,但具体作用机制尚未明确。目的:探讨FMT对葡聚糖硫酸钠(DSS)诱导的结肠炎小鼠内脏敏感性的影响。方法:小鼠饮用2. 0%DSS溶液制备结肠炎模型。将40只C57BL/6小鼠随机分为正常对照组(A组)、模型对照组(B组)、双歧杆菌三联活菌组(C组)、粪便滤液组(D组),分别给予0. 9%NaC l溶液、0. 9%NaC l溶液、双歧杆菌三联活菌液、粪便滤液灌肠。计算小鼠疾病活动指数(DAI)、结肠组织病理学评分;测定不同结直肠扩张(CRD)容积时腹壁肌电幅值变化;免疫组化法测定腰骶髓P物质(SP)、降钙素基因相关肽(CGRP)表达。结果:B组小鼠DAI、结肠组织病理学评分和腰骶髓SP表达明显高于A组、C组和D组(P 0. 05);而A、C、D三组相比差异无统计学意义(P 0. 05)。扩张容积为0. 04、0. 06、0. 08 mL时,B组腹壁肌电幅值显著高于A组、C组和D组(P 0. 05),且与SP表达之间存在正相关关系(P 0. 05)。四组小鼠腰骶髓CGRP表达相比差异无统计学意义(P 0. 05)。结论:FMT可改善结肠炎小鼠的内脏敏感性、减少腰骶髓SP表达,其降低内脏敏感性的作用可能与抑制脊髓背角SP表达有关。     

结肠黏膜低度炎症大鼠的内脏感觉变化及帕罗西汀的影响

目的探讨帕罗西汀对结肠低度炎症(low grade mucosal inflammation,LGMI)大鼠内脏敏感性的影响及机制。方法将48只SD大鼠按是否诱导出结肠低度炎症分为2大组:每组24只,建模方式为8%葡聚糖硫酸钠(DSS)自由饮用5天,再予蒸馏水饮用7天。每组再按是否予帕罗西汀干预细分为2小组:每组12只,干预方式为2 mg.kg-1.d-1连续灌胃14天。通过结肠内置气囊进行结肠扩张实验(CRD),观察大鼠腹肌收缩反射(AWR)并评分。处死大鼠,免疫组化法观察腰骶部脊髓c-Fos蛋白、P物质(SP)、降钙素基因相关肽(CGRP)表达情况。结果与非炎症组相比,低度炎症组大鼠的AWR评分及c-Fos、SP、CGRP表达均有显著升高(P0.05)。使用帕罗西汀干预后,低度炎症组大鼠的AWR评分、c-Fos、SP的表达与空白对照组无显著差异,而CGRP的表达仍比空白组显著升高(P0.05)。结论低度炎症可增加大鼠结肠的内脏敏感性,帕罗西汀可以降低结肠低度炎症大鼠的内脏敏感性,其机制可能与抑制脊髓水平c-Fos、SP、CGRP信号传递有关。     

CGRP在大鼠胃痛觉过敏形成机制中的作用

目的:探索降钙素基因相关肽(CGRP)相关的干预措施对胃痛觉过敏的影响,了解CGRP在胃痛觉过敏形成过程中发挥的作用．方法:成年SD古大鼠,均植入胃内气囊．观察伤害性扩张或CGRP iv对大鼠疼痛阈值的影响:观察由上述措施诱发内脏过敏的大鼠在给予CGRP受体特异性拮抗剂hCGRP8-37后疼痛阈值的变化:观察不同剂量CGRP和hCGRP8-37对疼痛阈值的影响．结果:CGRP iv后胃疼痛阈值为11．7±2．6 mmHg,对照组疼痛阈值为19．2±2．0 mmHg,生理盐水对照组则为18．3±2．5 mmHg,实验组与其他两组比较尸均<0．05．CGRP使大鼠的疼痛阈值降低．hCGRP8-37能逆转伤害性扩张和CGRP引起的内脏敏感性增高,该作用呈剂量依赖性(r=0．821,P<0．01)．结论:胃扩张刺激能引起胃敏感性增高,在此过程中CGRP具有重要的作用．     

肠易激综合征患者肠黏膜CGRP、SP水平的变化与临床症状的关系

[目的]探讨肠易激综合征(IBS)患者结肠黏膜降钙素基因相肽(CGRP)和P物质(SP)表达水平及与IBS临床症状的相关性。[方法]对腹泻型IBS(IBS-D组)20例、便秘型IBS(IBS-C组)8例和正常对照组5例各取乙状结肠黏膜标本,应用免疫组织化学染色法分别检测CGRP和SP;同时以评分法评价消化道症状;分析各组CGRP、SP表达水平与消化道症状的相关性。[结果]IBS-D组CGRP表达水平显著高于IBS-C组、正常对照组(0.27±0.08∶0.21±0.06、0.19±0.04,P0.05),IBS-C组与正常对照组比较差异无统计学意义。IBS-D组SP表达水平显著高于IBS-C组、正常对照组(0.27±0.11∶0.19±0.04、0.17±0.04,P0.05),IBS-C组与正常对照组比较差异无统计学意义。肠黏膜SP表达水平与IBS患者腹痛(r=0.495,P=0.007)、排便变稀(r=0.382,P=0.045)呈正相关,与排便困难(r=-0.485,P=0.009)、排便干结(r=-0.382,P=0.045)负相关;CGRP与排便变稀(r=0.401,P=0.034)正相关,与排便干结(r=-0.401,P=0.034)负相关。[结论]CGRP、SP可能参与IBS的病理生理过程并与临床症状密切相关。     

非糜烂性反流病患者食管黏膜SP和CGRP的表达

目的 观察非糜烂性反流病(NERD)和反流性食管炎(RE)患者食管黏膜内P物质(SP)和降钙素基因相关肽(CGRP)免疫反应阳性产物的表达,探讨其在NERD发病中的作用.方法 选择有典型胃食管反流症状并经反流性疾病诊断问卷(RDQ)调查、PPI试验、胃镜检查及食管24h pH检测诊断为GERD患者51例,其中RE组21例,NERD酸反流阳性组(NERD+组)12例,NERD酸反流阴性组(NERD-组)18例,采用免疫组化方法 在显微镜下观察NERD、RE患者食管黏膜内SP、CGRP的表达,应用彩色病理图像分析软件,分析计算SP、CGRP免疫反应的阳性指数(PI),并与正常对照组10例比较.结果 NERD-组食管黏膜内SP、CGRP的Pl值为96.77±31.74和24.76±29.15,明显高于NERD+组(73.64±31.38、9.78±10.30)、RE组(67.56±34.62、9.61±6.20)及正常对照组(59.82±46.15、8.64±12.12)(P均<0.05).结论 SP、CGRP在NERD-的患者食管黏膜内有明显表达,可能在食管内脏感觉中发挥着重要的作用.     

2型糖尿病大鼠肺组织内皮素-1、降钙素基因相关肽及P物质水平变化及其对肺动脉高压的影响

目的 探讨2型糖尿病大鼠肺组织内皮素-1(ET-1)、降钙素基因相关肽(CGRP)、P物质(SP)的变化.方法 3个月龄健康雄性Wistar大鼠10只,采用高脂饲料喂养联合30μg/g链脲佐菌素尾静脉注射制备2型糖尿病大鼠模型.另设正常对照组(n=8),给予普通饮食.造模成功后12周末股动脉放血处死大鼠,取右下肺组织行Weigert来复红弹力纤维染色,计算与呼吸性细支气管、肺泡管伴行的肺小动脉管壁厚度占血管外径百分比(WT%)以及管壁面积占血管总面积百分比(WA%).应用免疫组织化学方法观察肺组织ET-1、CGRP、SP表达水平.数据统计采用独立样本t检验.结果 与正常对照组比较,糖尿病组大鼠肺泡隔面积与视场总面积比(0.42±0.10 vs 0.29±0.06,t=5.842,P＜0.05)、肺动脉WT%(26%±8%vs 19%±9%,t=3.023,P＜0.05)和WA%(42%±8% vs 36%±9%,t=2.526,P＜0.05)均显著增加,ET-1、SP平均吸光度(ET-1:86±5 vs 83±4,t=2.402,P＜0.05;SP:101±4 vs 100±3,t=2.530,P＜0.05)和阳性面积/视场总面积比(ET-1:0.016±0.017 vs0.010±0.008,t=2.501,P＜0.05;SP:0.014±0.014 vs 0.009±0.009,t=2.127,P＜0.05)显著增加,CGRP平均吸光度和阳性面积/视场总面积比差异无统计学意义.结论 糖尿病大鼠存在肺动脉高压的病理结构改变,可能与其肺组织ET-1表达增加有关.     

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.