急性冠状动脉综合征患者巨噬细胞表达过氧化体增殖物激活型受体γ及炎症相关因子的变化

目的 探讨急性冠状动脉综合征患者外周血单核细胞源性巨噬细胞表达过氧化体增殖物激活型受体γ核因子κB、基质金属蛋白酶9和组织型基质金属蛋白酶抑制剂1的变化及其间的关系.方法 选取急性冠状动脉综合征患者48例、稳定型心绞痛患者22例为研究对象,抽取外周动脉血20 mL,分离单个核细胞,加巨噬细胞集落刺激因子培养得单核细胞源性巨噬细胞;用CD40配体刺激后,酶联免疫吸附法测定上清液中基质金属蛋白酶9和组织型基质金属蛋白酶抑制剂1浓度,逆转录聚合酶链反应检测过氧化体增殖物激活型受体γ、基质金属蛋白酶9和组织型基质金属蛋白酶抑制剂1 mRNA表达,免疫组织化学法检测核因子κ亚单位P65表达.结果 急性冠状动脉综合征组过氧化体增殖物激活型受体γ mRNA表达低于稳定型心绞痛组(0.24±0.04比0.39±0.06,P<0.001),核因子κ P65表达高于稳定型心绞痛组(0.42±0.06比0.27±0.02,P<0.001),基质金属蛋白酶9在上清液中的浓度及其mRNA表达明显高于稳定型心绞痛组(231.11±51.47μg/L比126.02±13.26μg/L和0.674±0.11比0.24±0.05,P<0.001),组织型基质金属蛋白酶抑制剂1在上清液中的浓度及其mRNA表达强度高于稳定型心绞痛组(139.80±31.54μg/L比112.25±12.68μg/L和0.42±0.09比0.33±0.06,P<0.05).过氧化体增殖物激活型受体γ mRNA表达与核因子κ P65和基质金属蛋白酶9的表达强度呈负相关(P<0.001),与组织型基质金属蛋白酶抑制剂1的表达强度不相关(P>0.05);核因子κ P65与基质金属蛋白酶9和组织型基质金属蛋白酶抑制剂1的表达强度呈正相关(P<0.001).结论 急性冠状动脉综合征患者外周血单核细胞源性巨噬细胞过氧化体增殖物激活型受体γ表达下调,核因子κ活性增强,基质金属蛋白酶9和组织型基质金属蛋白酶抑制剂1表达上调;过氧化体增殖物激活型受体γ可能通过调节核因子κ活性而调节基质金属蛋白酶9基因转录;但组织型基质金属蛋白酶抑制剂1表达可能不受过氧化体增殖物激活型受体γ调节.     

注射用血塞通对PCI术后急性心肌梗死病人炎症因子、基质金属蛋白酶的影响

目的观察注射用血塞通对PCI术后急性心肌梗死病人炎症因子、基质金属蛋白酶的影响。方法选择在本院就诊的80例急性心肌梗死病人,随机分为对照组和血塞通组,对照组术后给予常规阿司匹林、氯吡格雷、阿托伐他汀口服;血塞通组在对照组治疗基础上,加用注射用血塞通。2周后分别测定两组病人血清脑钠肽、超敏C反应蛋白、基质金属蛋白酶2及白细胞介素6的表达水平。结果血塞通组治疗2周后,血清中脑钠肽(427.8 pg/m L±39.9 pg/m L vs 964.4 pg/m L±67.5 pg/m L,P0.05)、超敏C反应蛋白(2.9 mg/L±0.4 mg/L vs 8.8 mg/L±0.9 mg/L,P0.05)、基质金属蛋白酶2(824.63 ng/m L±59.61 ng/m L vs 1 829.42 ng/m L±110.23 ng/m L,P0.05)及白细胞介素6(29.4μg/L±4.6μg/L vs 61.8μg/L±8.1μg/L,P0.05)较对照组均明显降低。结论注射用血塞通可减轻急性心肌梗死病人急诊介入治疗术后病人的心肌损伤。     

罗格列酮联合阿托伐他汀对单个核细胞合成组织因子的影响

目的:研究罗格列酮联合阿托伐他汀干预对无糖尿病的急性冠状动脉综合征(ACS)患者外周血单核细胞合成组织因子水平及组织因子活性的影响.方法:分离无糖尿病的ACS患者外周血单核细胞,分成对照组(等容积的二甲基亚砜)、阿托伐他汀(1 μmol·L-1)组、罗格列酮(1 μmol·L-1)组及二者联合组(阿托伐他汀1 μmol·L-1加罗格列酮1 μmol·L-1)组4个组,分别与所分离的外周血单核细胞共同孵育24 h后,用夹心酶联免疫吸附测定法检测细胞组织因子水平,用逆转录聚合酶链反应(RT-PCR)测定组织因子mRNA的表达,同时用底物发光法检测组织因子的活性.结果:与对照组相比较,阿托伐他汀组、罗格列酮组及罗格列酮联合阿托伐他汀组对无糖尿病ACS患者外周血单核细胞合成组织因子分别为[(3.69±0.91)ng/L、(3.27±0.46)ng/L、(1.90±0.26)ng/L:(5.78±1.29)ng/L,均P<0.01]、组织因子的活性分别为[(4.28±0.84)pmol/L、(5.37±0.59)pmol/L、(2.15±0.37) pmol/L:(16.21±3.23)pmol/L, 均P<0.01),及组织因子mRNA的相对半定量A值分别为[(0.22±0.07), (0.31±0.09), (0.14±0.05):(0.42±0.11),均P<0.01)均降低,且罗格列酮联合阿托伐他汀组比阿托伐他汀组、罗格列酮组降低更显著(P均<0.01).结论:阿托伐他汀和罗格列酮都可通过降低无糖尿病的ACS患者外周血单核细胞合成组织因子及组织因子活性,发挥抗组织因子、抗血栓形成的作用,且二者联合干预具有协同作用.因此,罗格列酮联合阿托伐他汀,可能有更佳的防治ACS作用.     

氟伐他汀对急性心肌梗死大鼠基质金属蛋白酶9表达的影响

目的 观察氟伐他汀对急性心肌梗死大鼠基质金属蛋白酶9表达的影响,以探讨他汀类药物改善急性心肌梗死后左心室重构的机制.方法 选用雄性Wistar大鼠47只,随机分为心肌梗死组、心肌梗死用药组、假手术组和假手术用药组,结扎大鼠冠状动脉前降支建立心肌梗死模型,术后心肌梗死用药组及假手术用药组饲氟伐他汀10 mg/(kg·d),心肌梗死组和假手术组不给予任何处理和干预.4周后测左心室血流动力学参数、左心室重量指数及基质金属蛋白酶9含量.结果 术后基质金属蛋白酶9含量和左心室舒张末压在假手术组和假手术用药组均较低,且组间无明显差别(P0.05),在心肌梗死组和心肌梗死用药组均高于假手术组(P<0.05),而在心肌梗死组又高于心肌梗死用药组(P<0.05).与假手术组比较,心肌梗死组和心肌梗死用药组大鼠左心室收缩压、左心室压最大上升速率及左心室压最大下降速率均明显下降(P<0.05),且心肌梗死组较心肌梗死用药组下降更明显(P<0.05).各组左心室重量指数无明显差别(P0.05).结论 氟伐他汀能抑制基质金属蛋白酶9的表达,从而阻止大鼠心肌梗死后心室重构,改善心脏功能.     

吡格列酮对老年急性心肌梗死伴2型糖尿病患者血清基质金属蛋白酶9的影响

目的探讨老年2型糖尿病患者口服吡格列酮对发生急性心肌梗死时血清基质金属蛋白酶9和C反应蛋白浓度的影响。方法选择合并2型糖尿病的老年急性心肌梗死患者37例,按发病前有无口服吡格列酮分为吡格列酮组(17例)和急性心肌梗死组(20例),另选择老年健康体检者23例作为对照组,抽血测定三组血清基质金属蛋白酶9和C反应蛋白的浓度,并进行比较。结果与对照组相比,急性心肌梗死组血清基质金属蛋白酶9(396.5±67.3μg/L比290.8±75.5μg/L)和C反应蛋白浓度(8.73±2.59 mg/L比3.21±1.11 mg/L)明显升高,吡格列酮可降低血清基质金属蛋白酶9浓度(339.2±79.8μg/L)和C反应蛋白浓度(6.33±2.25 mg/L)。结论吡格列酮可降低老年急性心肌梗死患者血清基质金属蛋白酶9和C反应蛋白水平,提示吡格列酮在改善胰岛素敏感性之外还对心血管系统有益。     

氧化低密度脂蛋白对人单核细胞组织因子和基质金属蛋白酶-9活性的影响以及阿托伐他汀的干预作用

目的:探讨他汀类降脂药阿托伐他汀潜在的降脂外机制。方法:人单核细胞来源的巨噬细胞,加入50mg/L氧化低密度脂蛋白(oxLDL)共培养10d,加或不加入不同浓度的阿托伐他汀(浓度范围0.01~0.5μmol/L);酶谱学分析基质金属蛋白酶-9(MMP-9)的活性;一期凝固法测定组织因子(TF)的促凝活性。结果:阿托伐他汀可抑制单核-巨噬细胞的增殖,呈现一定的剂量依赖关系(P<0.05),加入100μmol/L羟甲戊酸后,这种抑制作用消失;0.1μmol/L的阿托伐他汀可显著抑制单核-巨噬细胞表达MMP-9的活性;阿托伐他汀可呈剂量依赖性抑制TF的促凝活性(P<0.05)。结论:阿托伐他汀不仅可抑制单核-巨噬细胞的增殖,而且可抑制单核巨噬细胞活化下表达的MMP-9的活性以及TF的促凝活性。     

罗格列酮联合阿托伐他汀对单核细胞分泌肿瘤坏死因子α的影响

目的 研究罗格列酮联合阿托伐他汀干预对无糖尿病的急性冠脉综合征（ACS）患者外周血单核细胞分泌肿瘤坏死因子α（TNF-α）的影响。方法 分离无糖尿病的ACS患者外周血单核细胞,设置对照组（等容积的二甲基亚砜）、阿托伐他汀（1 μmol/L）组、罗格列酮（1 μmol/L）组及二者联合组（阿托伐他汀1 μmol/L加罗格列酮1 μmol/L组） 4个组,分别与所分离的外周血单核细胞共同孵育24 h后,用夹心酶联免疫吸附测定法检测细胞培养上清液TNF-α,用逆转录聚合酶链反应（RT-PCR）测定TNF-α mRNA的表达。结果 与对照组相比较,阿托伐他汀组、罗格列酮组及联合组对无糖尿病ACS患者外周血单核细胞分泌TNF-α［分别为(229±24)ng/L、(236±28)ng/L、(159±29)ng/L vs (306±40)ng/L,均P<0.05］及TNF-α mRNA的相对半定量吸光值（A）比值（分别为0.35±0.12,0.39±0.11,0.26±0.06 vs 0.78±0.14,均P<0.05）均降低,且罗格列酮联合阿托伐他汀组比阿托伐他汀组、罗格列酮组降低更显著（均P<0.05）。结论 阿托伐他汀和罗格列酮都可通过降低无糖尿病的ACS患者外周血单核细胞产生分泌TNF-α,发挥阿托伐他汀和罗格列酮的抗炎作用,且二者联合干预具有协同作用,防治效果更佳。     

急性冠脉综合征患者血浆sCD40L与血清基质金属蛋白酶水平的变化及其意义

目的：观察急性冠脉综合征（ACS）患者可溶性CD40配体（sCD40L）及血清基质金属蛋白酶-9（MMP-9）、血清组织金属蛋白酶抑制物-1（TIMP-1）水平变化及其相关性。方法：采用酶联免疫吸附法测定70例冠心病患者[ACS患者35例、稳定型心绞痛（SAP）患者35例]、35例非冠心病患者（正常对照组）sCD40L、MMP-9、TIMP-1的水平。结果：与正常对照组及SAP组比较,ACS组sCD40L[（2.73±0.92）μg/ml比（3.05±0.98）μg/ml比（4.72±1.15）μg/ml]、MMP-9[（152.38±54.22）ng/ml比（341.12±69.96）ng/ml比（574.2±139.20）ng/ml]水平明显升高（P均〈0.01）,而TIMP-1[（415.92±13.96）ng/ml比（249.32±36.80）ng/ml比（172.20±40.10）ng/ml]水平明显降低（P〈0.01）;且MMP-9与sCD40L呈正相关（r=0.42,P〈0.05）。结论：急性冠脉综合征患者可溶性CD40配体、血清基质金属蛋白酶-9水平升高,血清组织金属蛋白酶抑制物-1水平下降提示这两指标与粥样斑块不稳定相关,可作为判断粥样斑块不稳定的血清学指标。     

瑞舒伐他汀对老年收缩性心力衰竭病人基质金属蛋白酶的影响

目的探讨瑞舒伐他汀对老年心功能Ⅱ～Ⅲ级的收缩性心力衰竭病人基质金属蛋白酶(MMP)-1,MMP-8和金属蛋白酶组织抑制因子-1(TIMP-1)水平的影响。方法收集85例NYHAⅡ～Ⅲ级的老年收缩性心力衰竭病人,病情稳定后分为对照组(不接受瑞舒伐他汀治疗)和药物组(接受瑞舒伐他汀10 mg/d)。服药前及4周后检测并比较2组MMP-1、MMP-8和TIMP-1的水平。结果 4周后,药物组MMP-1的水平较对照组明显降低[(11. 3±3. 4)μg/L比(13. 2±3. 9)μg/L,P 0. 05],TIMP-1的水平较对照组明显升高[(568±106)μg/L比(498±111)μg/L,P 0. 01],MMP-8的水平较对照组无明显改变[(16. 6±6. 4)μg/L比(17. 6±6. 3)μg/L,P 0. 05]。结论瑞舒伐他汀可以降低收缩性心力衰竭病人MMP-1水平,升高TIMP-1水平,对MMP-8水平无明显影响。     

急诊冠状动脉介入患者术后无复流的预测因子和保护因素

目的探讨急性心肌梗死(AMI)患者行急诊PCI后发生无复流与血管性血友病因子(vWF)、B型钠尿肽(BNP)、负荷剂量阿托伐他汀的关系。方法选择行急诊PCI的AMI患者258例,分为无复流组(38例)和正常血流组(220例),比较2组患者肌钙蛋白I(cTnI)、高敏C反应蛋白(hs-CRP)、vWF、BNP、负荷剂量阿托伐他汀应用的差异,logistic回归分析无复流现象的危险因素及保护因素。结果与正常血流组比较,无复流组cTnI、hs-CRP、vWF、BNP显著升高[(8.2±1.2)μg/Lvs(3.1±1.0)μg/L,(31.6±4.9)mg/Lvs(23.3±4.0)mg/L,(738.0±94.7)μg/L vs(635.0±100.2)μg/L,(409.9±122.8)ng/Lvs(271.5±99.4)ng/L],差异有统计学意义(P<0.01);负荷剂量阿托伐他汀应用(10.5%vs 40.9%)比较差异有统计学意义(P<0.05)。多因素logistic回归分析显示,hs-CRP、vWF、BNP是无复流的危险因素。结论 hs-CRP、vWF、BNP是无复流现象的预测因子。负荷剂量阿托伐他汀应用可以减少无复流现象发生。     

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.