氨茶碱对支气管哮喘气道重塑大鼠肺组织MMP-9及其基因表达的调节

目的 观察氨茶碱对支气管哮喘气道重塑大鼠气道形态学和转化生长因子β1(TGF-β1)、基质金属蛋白酶-9(MMP-9)及其基因表达的调节作用.方法 24只SD大鼠随机分为正常组、模型组、治疗组(35 mg/kg),每组8只,除正常组外以卵蛋白致敏并吸入激发法制备大鼠哮喘模型,治疗组、模型组从第1次哮喘激发开始(第15天)分别给予氨茶碱、生理盐水1次/d灌胃给药,用药4 w后处死大鼠,取肺组织HE染色,彩色图像分析仪测量支气管壁面积、支气管平滑肌面积,采用免疫组化法测定TGF-β1含量,ELISA法测定肺组织MMP-9含量,RT-PCR法测定MMP-9 mRNA含量.结果 与正常组比较,模型组大鼠支气管壁面积、平滑肌面积、肺组织MMP-9含量及MMP-9 mRNA含量明显增加(P＜0.01);与模型组相比,治疗组大鼠支气管壁面积、平滑肌面积、肺组织TGF-β1、MMP-9、MMP-9 mRNA含量均显著降低(P＜0.01).结论 氨茶碱可通过下调哮喘气道重塑大鼠肺组织MMP-9 mRNA表达、抑制MMP-9合成、抑制TGF-β1产生从而抑制支气管哮喘大鼠气道重塑.     

SB203580对烟雾暴露的哮喘大鼠的影响

目的 建立烟雾暴露的支气管哮喘(简称哮喘)大鼠模型,观察p38有丝分裂原活化蛋白激酶(p38 mitogen-activated protein kinase,p38 MAPK)抑制剂SB203580对其的治疗作用.方法 将Wistar大鼠随机分为4组,即正常对照组、哮喘组、烟雾暴露的哮喘组及SB203580干预组.动物肺功能仪测定大鼠呼气阻力、吸气阻力及肺顺应性,观察肺组织病理学改变,通过ELISA检测大鼠肺组织中IL-4、IL-5和IL-8的表达.结果 与烟雾暴露的哮喘组相比,SB203580干预组大鼠的气道阻力显著下降,肺顺应性显著升高,差异有统计学意义(P＜0.05);气道炎症明显减轻;肺组织中IL-4、IL-5和IL-8的含量显著下降,差异有统计学意义(P ＜0.05).结论 p38 MAPK抑制剂SB203580可以改善烟雾暴露的哮喘大鼠的气道炎症,减轻其支气管收缩反应.     

咳喘宁对支气管哮喘大鼠气道重塑及MMP-9、TIMP-1的影响

目的 观察咳喘宁对支气管哮喘大鼠气道形态学和基质金属蛋白酶-9（MMP-9）、基质金属蛋白酶组织抑制剂-1（TIMP-1）的影响.方法 40只SD大鼠随机分为正常组、模型组、咳喘宁高、低剂量组（27 和13.5 g生药/kg体重）、桂龙咳喘宁胶囊对照组（0.41 g/kg体重）,每组8只.除正常组外以卵蛋白致敏并吸入激发法制备大鼠支气管哮喘模型,各治疗组均从第1次哮喘激发开始（造模第3周）至处死前每天灌胃给药,激发并给药4 w后处死大鼠,取肺组织HE染色,彩色图像分析仪测量支气管管壁厚度、平滑肌厚度,采用ELISA双抗体夹心法测定肺组织MMP-9、TIMP-1含量.结果 与正常组比较,模型组大鼠支气管管壁和平滑肌厚度、肺组织MMP-9、TIMP-1含量及二者比值明显增加（P＜0.01）;与模型组比较,各治疗组均可显著降低支气管管壁和平滑肌厚度（P＜0.01）,降低肺组织MMP-9、TIMP-1含量以及二者比值（P＜0.05或P＜0.01）;且咳喘宁高、低剂量组优于桂龙咳喘宁胶囊组（P＜0.05或P＜0.01）.结论咳喘宁可通过降低肺组织MMP-9和TIMP-1含量,调节二者比值,抑制支气管哮喘大鼠气道壁增厚和平滑肌增生肥大,从而抑制支气管哮喘大鼠气道重塑.     

止哮平喘方对哮喘大鼠气道高反应性的影响

目的 探讨止哮平喘方对哮喘大鼠模型气道高反应性的影响.方法 SD大鼠60只,随机分正常对照组、哮喘模型组、地塞米松治疗组、止哮平喘方小、中和大剂量组,每组10只.采用卵蛋白(OVA)致敏和激发方法复制哮喘大鼠模型,观察给药后各组大鼠的症状积分、肺溢流量和离体气管条对乙酰胆碱的收缩反应.结果 哮喘模型大鼠出现明显哮喘症状,其症状积分明显高于其他各治疗组(P ＜0.05,P＜0.01).止哮平喘方各治疗组大鼠肺溢流量变化值均明显低于哮喘模型组(P ＜0.05,P ＜0.01).止哮平喘方各治疗组大鼠气管螺旋条对乙酰胆碱的收缩反应均明显低于哮喘模型组(P＜0.05,P＜0.01).结论 止哮平喘方可以通过松弛气道平滑肌,降低气道高反应性而发挥平喘作用.     

血管内皮生长因子水平与大鼠支气管哮喘模型发病机制关系的研究

目的 探讨大鼠支气管哮喘(简称哮喘)模型支气管肺泡灌洗液(BALF)中血管内皮生长因子(VEGF)水平与哮喘嗜酸粒细胞(EOS)炎症及气道血管通透性之间的关系,以及吸入性激素的作用.方法 SD大鼠18只,随机分为对照组,哮喘模型组和地塞米松干预组各6只.以腹腔注射1%卵蛋白致敏和2%卵蛋白雾化吸入激发复制哮喘模型,干预组在每次激发前给予地塞米松干预.检测大鼠气道反应性,BALF中EOS百分数,VEGF(酶联免疫吸附法)及气道血管渗透指数.结果 BALF中EOS百分数,VEGF水平,气道反应性及气道血管渗透指数哮喘组明显高于对照组(P<0.05或P<0.01);经过6周吸入性激素治疗后,地塞米松组BALF中VEGF水平,EOS百分数,气道反应性及气道血管渗透指数较哮喘组明显降低(P<0.05或P<0.01),与对照组比较差异无统计学意义.相关分析显示,BALF中VEGF水平与EOS百分数呈正相关(r=0.76,P<0.01);VEGF水平与气道血管渗透指数呈正相关(r=0.84,P<0.01);VEGF水平与PC50呈负相关(r=-0.68,P<0.01).结论 大鼠哮喘模型BALF中VEGF水平增高,并与气道EOS百分数,气道反应性和气道血管渗透指数密切相关.该结果提示VEGF可能在哮喘的发病机制中起着重要作用.     

灵芝孢子对支气管哮喘豚鼠引喘潜伏期及类胰蛋白酶释放的影响

目的 研究灵芝孢子对支气管哮喘(简称哮喘)豚鼠引喘潜伏期及肥大细胞类胰蛋白释放的影响.方法 10%卵蛋白腹腔注射致敏,雾化吸入1%卵蛋白方式诱导复制哮喘动物模型.30只健康豚鼠随机分为对照组(A)、哮喘组(B)、灵芝组(C)3组,每组10只,分别用生理盐水,灵芝孢子灌胃15 d.测定哮喘豚鼠的引喘潜伏期及呼气相气道阻力(Re),计数支气管肺泡灌洗液(BALF)细胞总数及分类,肺组织HE染色和免疫组织化学观察肺组织病理变化及肥大细胞类胰蛋白酶分布情况.结果 ①灵芝组的引喘潜伏期明显较哮喘模型组延长,Re显著降低(P＜0.05).②哮喘BALF白细胞总数及嗜酸粒细胞比例较生理盐水组增高(P＜0.05),肺组织炎性病变明显;灵芝组BALF细胞总数、嗜酸粒细胞比例及肺组织炎性病变明显较哮喘组降低或减轻(P＜0.05).③哮喘组类胰蛋白酶染色阳性的肥大细胞计数明显较生理盐水组增多(P＜0.05),主要分布在气道黏膜下,肺泡间隔及血管周围;灵芝组类胰蛋白酶染色阳性的肥大细胞计数较哮喘组显著减少.结论 灵芝孢子有延长哮喘豚鼠引喘潜伏期,降低气道阻力,减轻肺组织炎性病变,抑制肥大细胞释放类胰蛋白酶的作用.     

钙调神经磷酸酶在支气管哮喘大鼠气道重塑中的作用

目的 通过测定支气管哮喘(简称哮喘)大鼠肺组织中钙调神经磷酸酶(calcineurin,CaN)蛋白、Mrna的表达及CaN的活性,探讨CaN在哮喘大鼠气道重塑中的作用.方法 将20只Wistar大鼠随机分为哮喘组和对照组,每组10只.鸡卵清白蛋白溶液致敏及激发复制大鼠哮喘模型.HE染色观察气道炎症情况;图像分析观察支气管管壁厚度;实时定量(Real-time)PCR测定肺组织中CaN Mrna水平;免疫组织化学法检测肺组织中CaN蛋白的相对表达量;生物化学法检测大鼠肺组织CaN活性;流式细胞仪测定外周血单个核细胞细胞周期时相分布;ELISA法测定血浆中白介素4(IL-4)和肿瘤坏死因子α(TNF-α)的含量.结果 ①哮喘组大鼠支气管管壁厚度较对照组明显增加(P＜0.01);②哮喘组大鼠肺组织中CaNmRNA水平的相对表达量、CaN蛋白的相对表达量及CaN的活性均较对照组高(分别P＜0.05、P＜0.01和P＜0.01);③哮喘组大鼠血浆中IL-4和TNF-α含量较对照组明显增加(分别P＜0.01,P＜0.05);④与对照组相比,哮喘组大鼠外周血单个核细胞处于G0/G1期的百分率降低,处于S期、S+G2/M期百分率增加(P值均＜0.01);⑤大鼠肺组织CaN活性分别与大鼠支气管管壁厚度呈正相关(P＜0.01),与处于S期、S+G2/M期的外周血单个核细胞百分率呈正相关(P值均＜0.05),与血浆中IL-4的含量呈正相关(P＜0.05);血浆中IL-4含量与TNF-α含量及大鼠支气管管壁厚度亦呈正相关(P值均＜0.05).结论 哮喘大鼠肺组织CaN的活性增加,其可能通过促进外周血单个核细胞的分裂、增殖及活化产生IL-4和TNF-α而参与哮喘气道重塑的形成.     

血管内皮生长因子水平与大鼠支气管哮喘模型发病机制关系的研究

目的 探讨大鼠支气管哮喘（简称哮喘）模型支气管肺泡灌洗液（BALF）中血管内皮生长因子（VEGF）水平与哮喘嗜酸粒细胞（EOS）炎症及气道血管通透性之间的关系,以及吸人性激素的作用.方法 SD大鼠18只,随机分为对照组,哮喘模型组和地塞米松干预组各6只.以腹腔注射1%卵蛋白致敏和2%卵蛋白雾化吸入激发复制哮喘模型,干预组在每次激发前给予地塞米松干预.检测大鼠气道反应性,BALF中EOS百分数,VEGF（酶联免疫吸附法）及气道血管渗透指数.结果 BALF中EOS百分数,VEGF水平,气道反应性及气道血管渗透指数哮喘组明显高于对照组（P〈0.05或P〈0.01）;经过6周吸人性激素治疗后,地塞米松组BALF中VEGF水平,EOS百分数,气道反应性及气道血管渗透指数较哮喘组明显降低（P〈0.05或P〈0.01）,与对照组比较差异无统计学意义.相关分析显示,BALF中VEGF水平与EOS百分数呈正相关（r=0.76,P〈0.01）;VEGF水平与气道血管渗透指数呈正相关（r=0.84,P〈0.01）;VEGF水平与PC50呈负相关（r=-0.68,P〈0.01）.结论 大鼠哮喘模型BALF中VEGF水平增高,并与气道EOS百分数,气道反应性和气道血管渗透指数密切相关.该结果提示VEGF可能在哮喘的发病机制中起着重要作用.     

SB203580对烟雾暴露的哮喘大鼠的影响

目的建立烟雾暴露的支气管哮喘(简称哮喘)大鼠模型,观察p38有丝分裂原活化蛋白激酶(p38 mitogen-activated protein kinase,p38MAPK)抑制剂SB203580对其的治疗作用。方法将Wistar大鼠随机分为4组,即正常对照组、哮喘组、烟雾暴露的哮喘组及SB203580干预组。动物肺功能仪测定大鼠呼气阻力、吸气阻力及肺顺应性,观察肺组织病理学改变,通过ELISA检测大鼠肺组织中IL-4、IL-5和IL-8的表达。结果与烟雾暴露的哮喘组相比,SB203580干预组大鼠的气道阻力显著下降,肺顺应性显著升高,差异有统计学意义(P<0.05);气道炎症明显减轻;肺组织中IL-4、IL-5和IL-8的含量显著下降,差异有统计学意义(P<0.05)。结论 p38 MAPK抑制剂SB203580可以改善烟雾暴露的哮喘大鼠的气道炎症,减轻其支气管收缩反应。     

偏苯三酸酐诱导职业性哮喘大鼠模型的研究

目的 以低分子量化工原料偏苯三酸酐(tri-mellitic-anhydride,TMA)作为致敏剂复制职业性哮喘大鼠模型.方法 采用大鼠背部皮内注射致敏剂致敏,超声雾化器雾化吸入致敏剂激发的方法复制职业性哮喘大鼠模型,以大鼠引喘潜伏期,血液和支气管肺泡灌洗液(bronchoalveolar lavage fluid,BALF)中细胞学检查、BALF中IL-4和INF-γ检测、血清IgE检测、大鼠离体气管条对乙酰胆碱的反应性、肺组织病理学检查为评判指标,考察TMA复制职业性哮喘大鼠模型的可行性.结果 TMA模型组引喘潜伏期较短(与正常对照组比较P＜0.05),血液及BALF中嗜酸粒细胞(eosinophil,EOS)百分比升高(与正常对照组比较P ＜0.05),血清中IgE升高(与正常对照组比较P＜0.05),BALF中IL-4升高、INF-γ降低(与正常对照组比较P＜0.05～0.01),模型组离体气管条对乙酰胆碱的反应性提高(与正常对照组比较P＜0.01),肺组织病理检查见肺支气管上皮细胞变性坏死脱落,支气管腔内可见大量EOS、单核细胞、淋巴细胞等炎性渗出物,以及管壁增厚、管腔狭窄等炎症表现.结论 通过行为学观察、血液和BALF中细胞学检查、血清IgE检测、BALF中细胞因子检测和肺组织病理检测可见TMA致大鼠哮喘模型具有职业性哮喘的主要特征,表明采用TMA作为造模剂,适当的剂量和致敏方法复制类似职业性哮喘动物模型是可行的.     

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.