急性脑梗死并发幽门螺旋杆菌感染者血脂水平及氧化应激反应的观察

目的通过检测急性脑梗死(ACI)并发幽门螺旋杆菌(Hp)感染者血清血脂、丙二醛(MDA)水平及超氧化物歧化酶(SOD)活性,观察Hp感染对血脂水平及氧化应激反应的影响。方法选择ACI组200例(Hp感染139例,非Hp感染61例)和健康对照组80名,检测血清Hp-IgG抗体和14C尿素呼气试验(14C-UBT),检测血清血脂、MDA水平及SOD活性。结果 ACI组Hp感染率(69.5%)显著高于对照组(33.8%)(P0.01)。Hp感染组血清TC、TG、LDL-C显著高于Hp非感染组,而HDL-C水平显著低于Hp非感染组(均P0.01)。Hp感染组血清MDA水平高于Hp非感染组,而SOD活性低于Hp非感染组,差异有统计学意义(P0.01)。Hp非感染组血清MDA水平高于对照组,而SOD活性低于对照组,差异有统计学意义(P0.01)。结论ACI并发Hp感染者,机体内血脂代谢紊乱加剧及氧化应激反应增强,可能是Hp感染加剧ACI病情的原因之一。     

血清脂联素、高敏C-反应蛋白与大动脉粥样硬化型脑梗死的临床相关性分析

目的探讨大动脉粥样硬化型脑梗死(acute cerebral infarction,ACI)患者的梗死面积及神经功能缺损程度与血清脂联素和高敏C-反应蛋白(high sensitivity C-reactive protein,hs-CRP)水平的关系。方法选取大动脉粥样硬化型脑梗死患者61例(ACI组)和健康体检者64例(对照组),并将ACI组按照患者梗死面积及神经功能缺损程度各分为三个亚组,分别检测其血清脂联素、hs-CRP水平,并进行比较。结果 ACI组治疗前血清脂联素水平明显低于对照组(P0.05),hs-CRP水平明显高于对照组(P0.05);小、中、大梗死亚组和轻、中、重脑卒中亚组的血清脂联素水平均依次增高,hs-CRP水平均依次降低,差异均有统计学意义(P0.05);血清脂联素和hs-CRP水平呈负相关(r=-0.84,P0.05)。结论大动脉粥样硬化型ACI患者的血清脂联素水平降低,而hs-CRP水平升高,两者呈负相关性;且两者的变化水平与脑梗死面积大小及神经功能缺损程度密切相关。     

神经元特异性烯醇化酶在急性脑梗死中的应用

目的探讨神经元特异性烯醇化酶(NSE)在急性脑梗死(ACI)中的临床价值。方法选择急性脑梗死患者60例(ACI组),检测患者入院第2天和治疗14 d后血清NSE,并与健康体检对照组40名清晨检测的NSE进行比较。结果 ACI组治疗前血清NSE水平显著高于对照组(P0.01),病灶大、病情重者NSE水平显著升高(P0.01)。ACI组治疗后NSE水平明显低于治疗前(P0.01)。结论 ACI患者血清NSE水平明显升高,对梗死灶大小及病情评估具有重要价值。     

高压氧对急性脑梗死患者的疗效及其对神经功能、血氧饱和度及M-CSF、ox-LDL、sICAM-1水平的影响

目的:探究早期高压氧治疗对急性脑梗死(ACI)患者的疗效及其对神经功能、血氧饱和度及血清巨噬细胞集落刺激因子(M-CSF)、氧化型低密度脂蛋白(ox-LDL)、可溶性细胞间黏附分子(sICAM)-1水平的影响。方法:2017年3月至12月来我院就诊的ACI者100例被随机均分为常规治疗组和高压氧组(在常规治疗基础上接受早期高压氧治疗),疗程14 d。观察比较两组治疗前后美国国立卫生研究院卒中量表(NIHSS)评分、血糖、血氧饱和度、血清乳酸、M-CSF、ox-LDL和sICAM-1水平。结果:随时间推移,两组NIHSS评分均显著降低(P0.05或0.01)。治疗后7d、14d、21d,高压氧组NIHSS评分均显著低于常规治疗组,P0.05或0.01。与常规治疗组比较,高压氧组治疗后血氧饱和度[(83.54±13.87)%比(99.29±14.62)%]显著升高,血糖[(5.89±2.36)mmol/L比(4.75±2.84)mmol/L]、血清乳酸[(5.53±2.63)mmol/L比(3.75±2.38)mmol/L]、M-CSF[(764.57±210.39)μg/L比(634.56±189.54)μg/L]、ox-LDL[(346.65±78.63)μg/L比(249.53±74.32)μg/L]和sICAM-1[(683.87±168.76)μg/L比(543.76±147.84)μg/L]水平均显著降低,P0.05或0.01。结论:早期高压氧治疗,可显著改善ACI患者的神经功能及血氧饱和度,降低血清中M-CSF、ox-LDL、sICAM-1水平。     

急性脑梗死患者MDA、H_2O_2、SOD和ABTS的表达及临床意义

目的探讨急性脑梗死患者血清丙二醛(MDA)、过氧化氢(H_2O_2)、超氧化物歧化酶(SOD)和抗氧化性(ABTS)的活性情况及临床意义。方法选取2017年3月至2018年8月期间西安市第九医院收治的ACI患者96例作为观察组,同时选取经影像学检查无异常的健康者96例作为对照组。根据观察组患者的不同的神经功能缺损程度,将其分为轻度脑梗死组33例、中度脑梗死组31例、重度脑梗死组32例;同时根据不同的脑梗死面积,将其分为小梗死组34例、中梗死组32例、大梗死组共30例。检测所有入组对象的血清MDA、H_2O_2、SOD和ABTS的活性情况。对比观察组和对照组的血清MDA、H_2O_2、SOD、ABTS水平,同时对比不同神经功能缺损程度以及不同脑梗死面积患者的血清MDA、H_2O_2、SOD、ABTS水平。结果观察组血清MDA、H_2O_2水平明显高于对照组,血清SOD水平和ABTS活性水平均低于对照组,差异有统计学意义(t=12.759～18.723,P <0.05);轻度组、中度组及重度组的血清MDA、H_2O_2、SOD、ABTS指标进行组间对比,差异有统计学意义(F=2.544～3.851,P <0.05);中度组与重度组MDA、H_2O_2水平高于轻度组,SOD、ABTS水平低于轻度组,比较差异有统计学意义(均P <0.05)。重度组MDA、H_2O_2水平高于中度组,SOD、ABTS水平低于中度组,比较差异有统计学意义(均P <0.05)。小梗死组、中梗死组及大梗死组的血清MDA、H_2O_2、SOD、ABTS指标进行组间对比,差异有统计学意义(F=2.675～3.597,P <0.05)。中梗死组与大梗死组MDA、H_2O_2水平高于小梗死组,SOD、ABTS水平低于小梗死组,比较差异有统计学意义(均P <0.05)。大梗死组MDA、H_2O_2水平高于中梗死组,SOD、ABTS水平低于中梗死组,比较差异有统计学意义(均P <0.05);梗死面积与急性梗死轻度(r=0.704,P <0.05)、中度(r=0.712,P <0.05)、重度(r=0.723,P <0.05)呈正相关。结论神经功能缺损程度越高的ACI患者血清MDA、H_2O_2水平越高,SOD、ABTS活性水平越低。在临床管理中,对ACI患者血清MDA、H_2O_2、SOD、ABTS水平进行检测,可有效识别患者的病情程度,对临床诊断、预后防治具有一定的临床意义。     

血清氧化型低密度脂蛋白水平与大动脉粥样硬化性脑梗死患者中国缺血性卒中亚型分型和神经功能缺损程度的相关性研究

目的探讨血清氧化型低密度脂蛋白(ox-LDL)水平与大动脉粥样硬化性(LAA)脑梗死患者中国缺血性卒中亚型(CISS)分型和神经功能缺损程度的相关性。方法选取2016年6月—2017年8月河南科技大学第一附属医院收治的LAA脑梗死患者60例作为观察组,根据CISS分型分为载体动脉阻塞穿支组(A组,n=33)、动脉-动脉栓塞组(B组,n=10)、低灌注/栓子清除下降组(C组,n=11)、混合机制组(D组,n=6);另选取同期于河南科技大学第一附属医院体检健康者54例作为对照组。比较对照组与观察组受试者一般资料和实验室检查指标,并比较不同CISS分型LAA脑梗死患者血清ox-LDL水平和美国国立卫生研究院卒中量表(NIHSS)评分;血清ox-LDL水平与LAA脑梗死患者CISS分型和神经功能缺损程度的相关分析采用Spearman秩相关分析。结果对照组与观察组受试者性别、吸烟史及血清高密度脂蛋白(HDL)、总胆固醇(TC)、三酰甘油(TG)水平比较,差异无统计学意义(P0.05);观察组患者年龄大于对照组,血清低密度脂蛋白(LDL)、ox-LDL水平高于对照组(P0.05)。A组、B组、C组患者血清ox-LDL水平低于D组(P0.05);A组、C组患者血清ox-LDL水平低于B组(P0.05)。A组、B组、C组患者NIHSS评分低于D组(P0.05);A组患者NIHSS评分低于C组(P0.05)。Spearman秩相关分析结果显示,血清ox-LDL水平与LAA脑梗死患者CISS分型无直线相关关系(rs=0.252,P0.05);血清ox-LDL水平与LAA脑梗死患者神经功能缺损程度呈正相关(rs=0.269,P0.05)。结论血清ox-LDL水平与LAA脑梗死患者CISS分型无直线相关关系,但与神经功能缺损程度呈正相关。     

强化阿托伐他汀治疗对老年急性脑梗死患者血清ox-LDL、CRP水平及神经功能的影响

目的探讨强化阿托伐他汀治疗对老年急性脑梗死(ACI)患者血清氧化低密度脂蛋白(ox-LDL)、C反应蛋白(CRP)水平及神经功能的影响。方法选择106例老年ACI患者,按照数表法随机分为观察组(n=53)和对照组(n=53),两组均给予常规药物治疗,对照组加用常规剂量的阿托伐他汀(20 mg/d),观察组加用强化剂量的阿托伐他汀(40 mg/d),于治疗前、治疗7 d、14 d后比较两组血清ox-LDL、CRP、神经功能及血脂水平,比较两组药物相关不良反应发生率。结果两组治疗7 d、14 d后CRP、血清ox-LDL、低密度脂蛋白胆固醇(LDL)-C、总胆固醇(TC)、三酰甘油(TG)水平及神经功能缺损脑卒中量表(NIHSS)评分较治疗前降低,治疗14 d后较治疗7 d后进一步降低,且观察组比对照组低,差异均有统计学意义(P<0.05)。两组血清高密度脂蛋白胆固醇(HDL-C)水平治疗前后比较、组间比较差异均无统计学意义(P>0.05)。治疗期间,两组药物相关不良反应发生率差异无统计学意义(P>0.05)。结论阿托伐他汀治疗老年ACI能显著改善患者的炎症状态,有效调节血脂水平、明显改善神经功能,但存在量效关系,强化剂量的效果更佳,且不显著增加不良反应,安全性好。     

氯吡格雷联合前列地尔治疗大脑中动脉狭窄所致急性脑梗死的临床疗效

目的观察氯吡格雷联合前列地尔治疗大脑中动脉狭窄所致急性脑梗死的临床疗效。方法选取2013年7月—2015年7月贵阳市云岩区人民医院收治的大脑中动脉狭窄所致急性脑梗死患者84例,根据入院顺序分为对照组和观察组,每组42例。对照组患者采取常规治疗,观察组患者在常规治疗基础上予以氯吡格雷联合前列地尔治疗;两组患者均连续治疗6个月。比较两组患者治疗前后血清糖化血红蛋白(HbA_(1c))、超敏C反应蛋白(hs-CRP)、超氧化物歧化酶(SOD)、纤维蛋白原(FIB)、丙二醛(MDA)水平,加拿大神经功能量表(CNS)评分和Barthel指数(BI)评分,临床疗效,治疗期间不良反应发生情况及随访1年内复发情况。结果治疗前两组患者血清HbA_(1c)、hs-CRP、SOD、FIB、MDA水平比较,差异无统计学意义(P0.05);治疗后观察组患者血清HbA_(1c)、hs-CRP、FIB、MDA水平低于对照组,血清SOD水平高于对照组(P0.05)。治疗前两组患者CNS评分、BI评分比较,差异无统计学意义(P0.05);治疗后观察组患者CNS评分低于对照组,BI评分高于对照组(P0.05)。观察组患者临床疗效优于对照组(P0.05)。两组患者治疗期间不良反应发生率比较,差异无统计学意义(P0.05)。观察组患者随访1年内复发率低于对照组(P0.05)。结论氯吡格雷联合前列地尔治疗大脑中动脉狭窄所致急性脑梗死的临床疗效确切,可有效降低患者血清HbA_(1c)、hs-CRP、FIB、MDA水平及复发率,提高血清SOD水平及患者日常生活活动能力,改善患者神经功能,降低复发风险,且安全性较高。     

老年急性脑梗死患者血清瘦素水平的变化及对临床预后的影响

目的探讨老年急性脑梗死患者的血浆瘦素水平与ACI患者神经功能及患者临床预后的关系。方法 2013年1至12月在该院急诊科收治的ACI患者165例,治疗前测量其血压、血脂、血糖和血清瘦素水平。根据患者血清瘦素水平三分位分组分为低、中、高水平组,每组55例。均接受常规治疗,评价所有患者治疗前和治疗14 d时的神经功能,并且比较治疗结束时两组患者的综合临床疗效。结果 (1)低水平组患者血清瘦素水平范围为(2.479~4.562)ng/L,中水平组为(4.623~8.328)ng/L,高水平组为(8.468~51.376)ng/L;(2)ACI患者血清瘦素水平与性别、体质指数、脑梗死部位、并发疾病以及血脂水平无关(P0.05),但是与年龄、发病时间以及吸烟有关(P0.05或P0.01);(3)低、中、高水平组的美国国立卫生研究院神经功能缺损程度评分(NIHSS)差异具有统计学意义(P0.01),相关分析显示NIHSS评分与血浆瘦素水平呈显著正相关(相关系数r=0.46,P0.01)。结论血清瘦素水平与老年ACI的神经功能和临床预后相关。     

鼠神经生长因子联合丹参川芎嗪注射液对急性脑梗死患者神经功能及血清氧化型低密度脂蛋白、巨噬细胞集落刺激因子、P选择素水平的影响

目的探讨鼠神经生长因子联合丹参川芎嗪注射液对急性脑梗死患者神经功能及血清氧化型低密度脂蛋白(ox-LDL)、巨噬细胞集落刺激因子(M-CSF)、P选择素水平的影响。方法选取安康市人民医院2014年11月—2017年7月收治的急性脑梗死患者86例,采用随机数字表法分为对照组与研究组,每组43例。在常规治疗基础上,对照组患者给予鼠神经生长因子,研究组患者在对照组基础上加用丹参川芎嗪注射液;两组患者均连续治疗14 d。比较两组患者临床疗效,治疗前后美国国立卫生研究院卒中量表(NIHSS)评分及血清ox-LDL、M-CSF、P选择素水平,观察两组患者治疗期间不良反应发生情况。结果研究组患者临床疗效优于对照组(P0.05)。治疗前两组患者NIHSS评分比较,差异无统计学意义(P0.05);治疗后研究组患者NIHSS评分低于对照组(P0.05)。治疗前两组患者血清ox-LDL、M-CSF、P选择素水平比较,差异无统计学意义(P0.05);治疗后研究组患者血清ox-LDL、M-CSF、P选择素水平低于对照组(P0.05)。两组患者治疗期间不良反应发生率比较,差异无统计学意义(P0.05)。结论鼠神经生长因子联合丹参川芎嗪注射液可有效改善急性脑梗死患者神经功能,降低血清ox-LDL、M-CSF、P选择素水平,临床疗效确切且安全性较高。     

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.