广西壮族人群SLC2A9基因多态性位点与原发性痛风的关联性研究

［摘要］　目的　探讨广西壮族人群可溶性载体2家族成员9（SLC2A9）基因单核苷酸多态性（SNPs）与原发性痛风的关联性。方法　收集广西壮族人群246例原发性痛风患者和202名健康对照者的临床资料及血尿酸（UA）、空腹血糖、甘油三酯(TG)、总胆固醇（TC）、高密度脂蛋白（HDL-C）、低密度脂蛋白（LDL-C）、肌酐（Cr）、尿素氮（BUN）等实验室指标,比较两组临床及实验室指标的差异。Taqman-MGB探针法检测SLC2A9基因4个位点(rs10489070、rs734553、rs3733591、rs16890979)的基因型,比较两组基因型及等位基因分布频率。结果　痛风组的体质量指数（BMI）、TG、TC、LDL-C、Cr、UA水平显著高于对照组（P<0.05）。有痛风石的患者年龄更大,病程更长,累及关节数更多,肾结石发生率更高,TG、TC、LDL-C、Cr、UA水平更高,差异均有统计学意义（P<0.05）。rs10489070和rs3733591在痛风组与对照组基因型及等位基因分布频率差异有统计学意义（P<0.05）,携带C等位基因的个体发生痛风的OR值分别为1.413（95%CI：1.009～1.980）和1.739（95%CI：1.331～2.271）。rs3733591（CC）（aOR=2.113,95%CI：1.536～3.951）、rs10489070（CC）（aOR=1.981,95%CI：1.123～3.156）是痛风发生的独立危险因素。rs3733591（CC）（aOR=2.358,95%CI：1.114～3.221）、rs10489070（CC）（aOR=2.115,95%CI：1.689～4.547）是痛风石发生的独立危险因素。结论　我国壮族人群中,SLC2A9基因的rs10489070（CC）和rs3733591（CC）基因型是痛风和痛风石的独立危险因素,但目前易感位点影响痛风发病的具体机制尚不明确,下一步需要进行相关SNPs功能的研究。     

可溶性载体2家族成员9基因的单核苷酸多态性与我国川东北地区汉族人群原发性痛风发病的相关性研究

目的 探讨SLC2A9(rs10489070)的单核苷酸多态性与我国川东北地区汉族人群痛风发病及血尿酸水平的相关性.方法 采用Taqman(R)探针法检测痛风组(151例原发性痛风患者)和对照组(176名健康体检者)rs10489070(C＞G)位点基因型,分析基因型及等位基因在2组的分布频率,并比较不同基因型实验室指标及临床资料的差异.统计学处理采用t检验x2检验和(或)Fisher精确概率法.结果 rs10489070( C＞G)位点在所有研究对象的基因型分布均处于Hardy-Weinberg平衡.CC型在痛风组的分布频率显著高于对照组(78.8％和68.8％,P＜0.05),而CG型则低于对照组(19.9％和30.1％,P＜0.05);等位基因C和G在2组的分布差异无统计学意义(P＞0.05).有痛风石(14例)与无痛风石(97例)痛风患者基因型分布频率差异有统计学意义(P＜0 05),CG基因型在有痛风石者的分布频率显著低于无痛风石患者(0和22.7％,P＜0.05).携带CC基因型患者血尿酸及血糖水平均高于未携带CC基因型患者,但差异无统计学意义(P＞0.05).结论 SLC2A9 rs 10489070(C ＞G)的多态性可能与我国川东北地区汉族人群原发性痛风的易感性相关,携带CC基因型个体更易患痛风,CG基因型则可能对痛风的发病及痛风患者痛风石的形成具有保护作用.     

中国男性痛风患者SLC2A9基因单核苷酸多态性与尿酸水平的关系

目的 SLC2A9是新近发现的尿酸转运子,该基因单核苷酸多态性可影响血清尿酸水平。本研究检测SLC2A9基因第6内含子rs7442295多态性在中国男性痛风和原发性高尿酸血症患者中的分布情况以及与尿酸代谢指标的相关性。方法 选取268例原发性痛风患者和288名健康志愿者,分别检测血压、体质量指数、血尿酸、血糖、血脂、肾功能水平,并同时提取外周血DNA,运用高分辨率熔解曲线(HRM)分析rs7442295基因型,并用测序法证实。统计学方法采用x2检验及t检验。结果 运用HRM技术能准确区分rs7442295 A/A和A/G基因型,而G/G基因型则在本研究人群中未发现。A/A和A/G基因型在人群分布频率分别是96.2％和3.8％。与健康对照组相比,痛风组的A/A和A/G基因型频率及A、G等位基因频率分布差异无统计学意义(x2=0.003,P=0.82; x2=0.003,P=1.00),但携带A/G基因型个体的尿酸水平[(293±100) μmol/L]明显低于携带A/A基因型的个体[(392±133) μmol/L]（t=2.426,P＜0.01）,且正常尿酸组内A/G基因型频率明显高于高尿酸组(x2=6.279,P=0.01）,基于HRM技术的基因分型结果与测序法所得结果完全一致。结论 SLC2A9基因rs7442295多态性可能是评估中国汉族男性人群原发性高尿酸血症危险性的一个遗传学标志,HRM技术简单、方便、快速,并实现闭管检测,非常适合单核苷酸多态性分析。     

内蒙古汉族人群硒蛋白S基因rs34713741多态性与大肠癌发病风险的关系

目的探讨内蒙古地区汉族人群硒蛋白(Sel)S基因rs34713741多态性与大肠癌发病风险的关系。方法采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)技术检测126例内蒙古地区汉族大肠癌(CRC)患者(CRC组)及135例健康人群(对照组)进行SelS基因分型。结果 SelS基因rs34713741基因型CC、CT、TT在CRC组和对照组间分布频率分别为49. 2%、40. 5%、10. 3%和59. 3%、34. 8%、5. 9%,差异无统计学意义(P0. 05);等位基因C、T在CRC组和对照组分布频率分别为69. 4%、30. 6%和76. 7%、23. 3%,差异无统计学意义(P0. 05);对CRC组分层分析发现,远端大肠组和对照组CC、CT、TT基因型分布频率比较差异有统计学意义(P0. 05),远端大肠组CC基因型分布频率明显低于对照组,携带T等位基因的CT/TT个体患CRC的风险是CC基因型个体的1. 719倍(OR=1. 719,95%CI:1. 144～2. 582)。结论 SelS基因rs34713741多态性与远端CRC的发病具有相关性,T等位基因可能是内蒙古汉族人群远端CRC发病的危险因素之一。     

SLC52A3基因多态性与鼻咽癌易感性的关系

目的探讨核黄素转运蛋白SLC52A3基因单核苷酸多态性(SNPs)与鼻咽癌易感性的关系。方法采用Haploview软件从国际人类基因组单体型图计划(Hap Map)公布的北京汉族人群基因型数据库中筛选出SLC52A3基因3个标签SNPs(rs13042395、rs3746803及rs3746804),收集147例鼻咽癌患者外周血标本并采用直接测序法进行基因分型,选取159例健康体检者的外周血作对比,采用Hardy-Weinberg平衡分析3个SNPs位点的遗传平衡情况,比较鼻咽癌患者与健康对照rs13042395、rs3746803及rs3746804基因型和等位基因的分布差异并计算比值比(OR)及其95%置信区间(CI)来评价以上SNPs与鼻咽癌易感性的关系,同时分析SLC52A3 SNPs与常见临床病理参数的关系。结果 147例鼻咽癌患者rs13042395、rs3746803及rs3746804基因型和等位基因的分布符合Hardy-Weinberg平衡。疾病组与对照组rs13042395基因型分布的差异无统计学意义(P>0.05),但疾病组等位基因C的比例高于对照组(P<0.05),其中以CC基因型为参照,TT及CT+TT基因型发生鼻咽癌的风险降低至0.522、0.575倍(P<0.05),T相对于C等位基因发生鼻咽癌的风险降低至0.719倍(P<0.05)。rs3746804分布上,疾病组TT基因型及等位基因T的比例均低于对照组,差异有统计学意义(P<0.05),其中以CC基因型为参照,CT、TT及CT+TT基因型发生鼻咽癌的风险降低至0.501、0.400和0.466倍(P<0.05);以C等位基因为参照,T发生鼻咽癌的风险降低至0.588倍(P<0.05)。rs3746803基因型及等位基因分布与鼻咽癌易感性无关。结论SLC52A3 rs13042395、rs3746804与鼻咽癌易感性及临床分期有关,其中携带等位基因T的鼻咽癌发生风险降低,在鼻咽癌早期筛查中有一定价值。     

沉默信息调节因子1基因多态性与老年原发性高血压的相关性研究

目的分析沉默信息调节因子1(SIRT1)基因多态性与老年原发性高血压的关系。方法选择2016年1月～2019年3月广东医科大学附属医院老年医学中心住院的老年原发性高血压患者500例(高血压组),另选同期我院健康体检中心的健康体检者500例(对照组),采用SNaPshot技术对2组SIRT1基因启动子区rs3758391多态性位点行基因型检测,运用荧光定量PCR方法检测外周血单个核细胞SIRT1基因mRNA相对表达量,进一步分析其与rs3758391位点基因型的关系。结果高血压组SIRT1基因rs3758391位点的TT、CT和CC基因型频率分别为62.8%、31.6%和5.6%,对照组分别为73.0%、24.2%和2.8%,差异有统计学意义(P=0.001);高血压组SIRT1基因rs3758391位点C等位基因频率明显高于对照组(21.4%vs 14.9%,P=0.001)。SIRT1基因rs3758391位点显性基因模型、隐性基因模型及等位基因模型比较,差异有统计学意义(P0.05,P0.01)。高血压组外周血单个核细胞SIRT1基因mRNA相对表达明显低于对照组(0.38±0.09 vs 0.92±0.15,t=30.87,P0.05);对照组CC+CT基因型SIRT1基因mRNA相对表达明显低于TT基因型(0.67±0.12 vs 1.01±0.16,t=10.03,P0.05)。结论 SIRT1基因启动子区rs3758391位点多态性与老年原发性高血压易感性有关,C等位基因可能是老年原发性高血压的危险因素。     

SLC30A8和PTPRD基因多态性与南京地区中老年人群2型糖尿病的相关性研究

目的 探讨溶质载体家族30/锌转运体,成员8(SLC30A8)基因(rs13266634和rs3802177)和蛋白酪氨酸磷酸酶受体D(PTPRD)基因(rs17584499)单核苷酸多态性与南京地区中老年人群2型糖尿病的相关性.方法 对南京地区40岁以上人群行75 g口服葡萄糖耐量试验及问卷调查,选取2型糖尿病1 758例(糖尿病组),正常对照1 970名(对照组),提取外周血基因组DNA,对其SLC30A8和PTPRD基因3个目标位点的基因型进行检测,分析与2型糖尿病的关系.结果 SLC30A8基因位点rs13266634在糖尿病组的基因型频率(CC、CT和TT)分别为35.9％、48.2％和15.9％,对照组为33.3％、48.8％和17.9％,糖尿病组C等位基因频率高于对照组(x2=3.986,P=0.046),C等位基因携带者患2型糖尿病的风险是T等位基因的1.158倍[优势比(OR)=1.158,P=0.005].位点rs3802177在糖尿病组的基因型频率(CC、CT和TT)分别为35.3％、48.2％和16.5％,对照组为32.1％、49.9％和18.0％,糖尿病组C等位基因频率高于对照组(x2=4.085,P =0.043),C等位基因携带者患2型糖尿病的风险是T等位基因的1.162倍(OR =1.162,P=0.004).PTPRD基因位点rs17584499在糖尿病组的基因型频率(CC、CT和TT)分别为81.9％、16.9％和1.2％,对照组为82.4％、16.5％和1.1％,两组基因频率分布无统计学差异(x2=0.274,P=0.600).结论 SLC30A8基因位点rs13266634和rs3802177的C等位基因可能是2型糖尿病的风险基因,与南京地区中老年人群2型糖尿病相关,未发现PTPRD基因(rs17584499)与本地区2型糖尿病相关.     

NOS2 C-1173T、G-954C单核苷酸双重多态性与高血压病的关系

目的研究中国汉族人群诱导型一氧化氮合酶(NOS2)基因启动子区C-1173T、G-954C单核苷酸双重多态性(SNP)及其基因型组合与高血压病的相关性.方法随机选择的高血压病个体192人(男97例,女95例)以及健康汉族个体109例(男61例,女48例)检测血白细胞基因DNA,利用嵌巢式等位基因特异性引物PCR技术检测NOS2 C-1173 T(C-T)、NOS2 G-954C SNP(G-C),并应用聚类分析其基因多态性特征.结果 NOS2 C-T与G-CSNP基因型分布高血压病组CC基因型频率(64.06%)与正常对照组(59.17%)相比无差异(P>0.05),TT基因型频率较正常对照组低(P<0.05,χ24.804).在女性高血压病患者T等位基因频率与正常对照组无显著性差异;而在男性高血压病患者T等位基因频率较正常对照组低(P<0.05,χ25.182).NOS2 C-T与G-C 组合基因型分布发现高血压病组携带TT+GG与TT+GC总频率明显低于正常对照组(P<0.05,χ24.804),男性高血压病患者尤为明显(P<0.05,χ24.2876).结论 (1)中国汉族人群NOS2 C-1173 T 多态性与男性患高血压病有相关性;NOS2 G-954C SNP多态性与高血压病无关.(2)在高血压病男性病人携带 T-1173T+NOS2 G-954G与NOS2 T-1173T+NOS2 G-954C频率较正常对照组低.     

三基因单核苷酸多态性与汉族人群2型糖尿病的相关性研究

目的：研究rs3923113-GRB14,rs1802295-VPS26A,rs7178572-HMG20A三基因单核苷酸多态性（SNPs）与2型糖尿病（T2DM）及相关代谢指标的相关性。方法：用高分辨率溶解曲线（HRM）小片段基因分型方法检测300例T2DM者及300例健康体检者3SNP位点基因型及等位基因频率分布。结果：各SNP基因型分布符合遗传平衡定律。rs231362（KCNQl）的风险基因C患病风险是T等位基因的1．058倍（P=0．012,OR=1．058,95％CI：1．012-1．106）。rs231362（KCNQl）的3种基因型（TT、CT、CC）在T2DM组与对照组中的分布频率分别为0．7％、19．9％、75．6Voo和2．7％、25．6％、71．7％,2组基因型分布差异有统计学意义（P=0．031）。该位点在其隐性模型中（CCVSCT＋TT）,2组差异有统计学意义（P=0．028,OR=1．11,95％CI：1．01～1．22）。rs3923113-GRBl4、rs7178572-HMG20A基因型分布在病例组与对照组中未见显著性差异。我们分析了对照组血糖血脂与各SNP位点基因型之间的关系,rs3923113在显性模型[（TT＋GT）／GG]下TT＋GT组总胆固醇（Tc）值低于GG组;TT＋GT组高密度脂蛋白（HDL-C）1．07（0．90-1．19）mmol／L低于GG组1．21（1.02-1．41）mmol／L,P值分别为0．017与0．036。结论：rs231362-KCNQl可能与中国人群T2DM发病有关。rs3923113-GRBl4与TC及HDL-C升高有关。     

TCF7L2基因rs290487多态性与2型糖尿病相关研究

采用PCR—RFLP技术,对100例正常个体和100例T2DM患者的TCF7L2基因rs290487多态性进行检测,结果：在病例组和对照组TCF7L2的多态性位点rs290487等位基因的频数分布差异无统计学意义（x^2=0．251,P〉0．05）;基因型的频数分布差异无统计学意义（x^2=0．248,P〉0．05）。Logistic回归显示,与CC基因型比较,携带突变等位基因T的基因型（CT和TT）并没有改变患T2DM的风险,该多态性与T2DM的易感性关联无统计学意义。结论：在中国济南地区人群的TCF7L2基因rs290487多态性可能与T2DM无关     

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。     

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.