急性髓系白血病骨髓单个核细胞CD11a的表达及临床意义

目的:探讨淋巴细胞功能相关抗原-1(LFA-1)的α链CD11a在急性髓系白血病(AML)的表达情况及临床意义。方法:采用免疫酶标ABC法检测25例初治AML患者和8例血液系统非恶性肿瘤患者为对照的骨髓单个核细胞CD11a的表达,并追踪观察AML患者的疗效。结果:CD11a在AML患者骨髓单个核细胞的表达率(37.02±13.30)%,明显低于对照组(87.13±5.38)%(P<0.05)。化疗后未缓解组AML患者发病时骨髓单个核细胞CD11a的表达率(47.09±10.55)较完全缓解组(29.11±9.36)%高(P<0.05)。结论:CD11a在AML患者骨髓单个核细胞表达异常,可能与白血病细胞逃脱机体免疫监控及从造血微环境释出有关。检测AML患者骨髓单个核细胞CD11a的表达水平对AML的预后判断有一定意义。     

慢性乙型肝炎患者B7-H1和PD-1信号途径表达的特点

目的 初步探讨免疫细胞协同共刺激分子途径之一--B7-H1和PD-1表达在慢性乙型肝炎(CHB)患者中的特点.方法 收集11例CHB患者和16例健康人的外周血肝素抗凝标本,流式细胞技术检测CHB患者外周血髓样树突细胞(mDC)和T淋巴细胞上B7-H1和PD-1的表达.数据比较采用t检验.结果 CHB患者外周血CD3~+T淋巴细胞、CD4~+T淋巴细胞、CD8~+T淋巴细胞和mDC上B7-H1阳性表达率分别为(40.69±14.49)%、(42.84±11.19)%、(33.48±14.07)%和(16.60±4.04)%.健康对照者分别为(14.66±10.11)%、(4.62±3.84)%、(1.89±2.31)%和(0.49±0.37)%,CHB患者B7-H1在T淋巴细胞和mDC上的表达水平均明显高于健康者,差异具有统计学意义(t=-2.884,t=-10.894,t=-7.378,t=-13.182;均P<0.05).CHB患者CD3~+T淋巴细胞、CD4~+T淋巴细胞和CD8~+T淋巴细胞上PD-1阳性表达率分别为(12.45±6.36)%、(11.42±6.20)%和(13.03±6.71)%,健康对照者分别为(7.80±3.53)%、(7.12±2.60)%和(7.88±3.74)%.CHB患者PD-1在T淋巴细胞上的表达水平也均明显高于健康者,差异具有统计学意义(t=-2.323,t=-2.355,t=-2.439;均P<0.05).结论 B7-H1和PD-1在CHB患者外周血mDC和T淋巴细胞上表达较高.     

冠心病患者树突状细胞的功能及依那普利干预效应

目的研究冠心病(CHD)患者树突状细胞(DC)的功能状态及血管紧张素转化酶抑制剂(ACEI)的影响。方法分离CHD患者及体检健康者外周血单个核细胞(PBMC),在含重组人粒细胞巨噬细胞集落刺激因子(rhGMCSF)、重组人白介素4(rhIL4)培养条件下制备DC。CHD患者的DC并加以依那普利干预。用流式细胞仪检测DC表面共刺激分子CD86(B72)的表达,混合淋巴细胞反应(MLR)检测DC对同种异体T淋巴细胞的刺激能力。结果与正常人比较,CHD患者DC表面CD86的表达明显增高(84.1±2.6vs59.2±10.0,P<0.001),对T淋巴细胞刺激的能力增强(1.3±0.2vs0.7±0.2,P<0.001),CD86的表达与C反应蛋白水平呈正相关(r=0.72,P<0.01);培养基中依那普利终浓度分别为1,10,100ng/mL时,CHD患者DC表面CD86的表达明显降低(分别为75.3±5.1,66.9±4.1,58.8±5.3比84.1±2.6,P<0.001),对T淋巴细胞刺激的能力下降(A值分别为1.0±0.2,0.8±0.2,0.7±0.1比1.3±0.2,P<0.001)。结论CHD患者DC处于激活状态,DC可能参与了CHD的发病。ACEI对CHD患者DC功能有明显的抑制作用,可能是其抗动脉粥样硬化的机制之一。     

自身免疫性血细胞减少症患者骨髓CD+5B细胞数量变化及其临床意义

目的探讨自身免疫性血细胞减少症患者骨髓CD5 B细胞数量及其临床意义。方法2001-032002-04对中国医学科学院血液病医院的住院患者14例检测自身免疫性溶血性贫血(AIHA)和Evans综合征和22例免疫相关性全血细胞减少症(IRP)及10名正常对照骨髓CD5 B细胞数量并与临床及实验室指标做相关分析。结果AIHA、Evans综合征和IRP患者CD5 B细胞数量[(34·64±9·81)%,(35·81±16·83)%]高于正常人[(12·0±1·97)%],(P<0·05),CD5 B细胞的数量与补体C3呈负相关(P<0·05),与间接胆红素呈正相关(P<0·05);与Evans综合征患者血小板抗体PAIgG(P<0·05)、PAIgM(P<0·05)呈正相关;与临床疗效呈负相关(P<0·05)。结论CD5 B细胞在自身免疫性血细胞减少症的发病机制中可能具有重要意义。     

急性冠状动脉综合征患者B7∶CD28/CTLA4共刺激分子的表达

目的:探讨急性冠状动脉综合征(ACS)患者外周血中单核细胞共刺激分子CD28、细胞毒T淋巴细胞抗原(CTLA)4、CD80(B7-1)的变化,探讨这些分子在发病中的意义。方法:采用直接荧光标记流式细胞仪测定23例ACS患者(ACS组)和31例稳定型心绞痛(SA)患者(SA组)入院时外周血CD4 ,CD8 T淋巴细胞CD28、CTLA4、B7-1分子的表达,同时选健康人群15例作为对照(对照组)。结果:与对照组相比,SA组及ACS组发病时CD4 ,CD8 T淋巴细胞表面共刺激分子CD28均显著升高(均P<0.01);SA组与ACS组比较差异无统计学意义。与对照组相比,SA组CD4 ,CD8 T淋巴细胞表面CTLA4表达均显著升高(P<0.01);而ACS组CD4 ,CD8 T淋巴细胞表面CTLA4表达均显著下降(P<0.01)。各组B7-1的表达差异无统计学意义。结论:①共刺激分子B7-1:CD28/CTLA4途径参与了冠心病的发病过程;②ACS的强烈的炎症反应与CT-LA4的低表达有关。     

特发性血小板减少性紫癜患者外周血淋巴细胞协同刺激分子B7的表达

目的　探讨B淋巴细胞表面协同刺激分子B7(B7 1、B7 2 )在特发性血小板减少性紫癜 (ITP)中的变化。方法　用流式细胞术检测 30例初发ITP患者和 15例正常人对照外周血淋巴细胞协同刺激分子B7 1(CD80 + )、B7 2 (CD86 + )表达率。结果　ITP患者外周血淋巴细胞CD86 + 、B细胞表面CD86 (CD1 9+ CD86 + CD1 9+ )表达率明显高于正常人 (P <0 .0 5 ) ,而CD80 + 、CD1 9+ CD80 + CD1 9+ 表达率相对于正常人无显著性差异 (P >0 .0 5 )。结论　ITP患者CD86 + 的改变可能参与ITP自身免疫的病理机制     

CD28/CTLA-4:B7在特发性血小板减少性紫癜患者外周血淋巴细胞中的表达及意义

目的:探讨特发性血小板减少性紫癜(ITP)患者外周血淋巴细胞CD28、CTLA-4(CD152)、B7-1(CD80)及B7-2(CD86)的表达及意义。方法:采用免疫荧光标记和流式细胞术检测41例ITP患者和40例健康对照者外周血CD3+CD28+细胞、CD3+CD152+细胞、CD80+CD19+细胞和CD86+CD19+细胞分别占淋巴细胞的比例及血小板表面相关抗体水平,进行2组对比、分析。结果:与正常对照组相比,急性ITP患者外周血CD3+CD28+细胞和CD3+CD152+细胞差异无统计学意义(P0.05),CD80+CD19+细胞增多(P0.05),CD86+CD19+细胞显著增多(P0.01),慢性ITP患者CD86+CD19+细胞增多(P0.05);急性ITP患者外周血CD86+CD19+细胞较慢性ITP患者增多(P0.05);与正常对照组相比,急性ITP患者PAIg's、PAIgG和PAIgM水平显著增高,慢性ITP患者PAIgG水平增高;CD80、CD86表达与PAIgG水平之间存在显著的相关性(均P0.01)。结论:ITP患者外周血B淋巴细胞上CD86和CD80表达均异常,可能与其发病相关。     

炎症性肠病患者外周血单个核细胞细胞毒性 T淋巴细胞相关抗原4的表达

背景:细胞毒性T淋巴细胞相关抗原(CTLA)4是一种重要的免疫细胞共刺激分子,主要表达于活化的T淋巴细胞,对T细胞的激活起抑制作用。目的:通过检测炎症性肠病(IBD)患者外周血单个核细胞表面CTLA4的表达,探讨CTLA4在IBD发病中的作用和功能。方法:将18例活动性溃疡性结肠炎(UC)、4例活动性克罗恩病(CD)患者以及21名健康对照者外周血单个核细胞分离后,以流式细胞仪检测细胞表面CTLA4、CD4 和CD8 的表达。结果:自然状态下,UC和CD患者CD4 CTLA4 表达显著高于对照组(8.2%±4.7%对1.4%±1.3%,P<0.001;4.3%±2.9%对1.4%±1.3%,P=0.011);CD8 CTLA4 表达亦显著高于对照组(9.1%±7.2%对0.9%±0.3%;8.7%±3.5%对0.9%±0.3%,P均<0.001)。经植物血凝素(PHA)刺激后,IBD患者和对照组外周血单个核细胞CTLA4的表达均增加;CD组CD8 CTLA4 表达显著高于对照组(35.0%±10.9%对18.1%±10.1%,P=0.005)。结论:活动性UC和CD患者外周血单个核细胞CTLA4表达增强,提示T细胞激活第二信号通路B7/CD28/CTLA4在IBD的发病过程中起重要作用。     

扁桃体灭活菌株对IgA肾病扁桃体CD4+ CD25+细胞和J链产生的影响

目的:以扁桃体隐窝内甲型链球菌(HS)灭活菌株刺激IgA肾病(IgAN)患者和非肾炎患者扁桃体淋巴细胞,观察未刺激及刺激后CD4 CD25 细胞和分泌J链IgA细胞数量,探讨IgAN的发病机制。方法:(1)收集37例IgAN患者及37例非肾炎慢性扁桃体炎患者手术摘除的扁桃体;(2)分离鉴定两组患者扁桃体隐窝内细菌及分离培养扁桃体淋巴细胞;(3)以分离最多的灭活菌株HS体外刺激扁桃体淋巴细胞72h;(4)以流式细胞仪检测扁桃体淋巴细胞CD4 CD25 细胞数,以原位杂交技术检测J链mRNA表达,以免疫荧光及荧光原位杂交技术同步分析分泌J链IgA细胞。结果:(1)两组患者均有甲型链球菌,且甲型链球菌在分离的细菌中是最多的。两组患者的细菌谱和细菌量无统计学差异。(2)未刺激、非肾炎患者HS(HS-controls)、IgAN患者HS(HS-IgAN)刺激后CD4 CD25 细胞数[(0.98±0.204)% vs (3.58±0.554)%,P<0.05,(1.37±0.214)% vs (5.78±0.562)%,P<0.05,and(1.43±0.202)% vs (6.05±0.521)%,P<0.05],IgAN组与非肾炎组比较,前者均显著低于后者。HS对IgAN组CD4 CD25 细胞的刺激指数(stimulation index,SI)显著低于非肾炎组(P均<0.05)。(3)未刺激、HS-controls、HS-IgAN刺激后J链mRNA阳性IgA细胞[(11.9±3.1)% vs (6.5±1.5)%,P<0.05,(33.5±5.7)% vs (13.9±1.2)%,P<0.05,and(35.1±6.2)% vs (13.9±1.2)%,P<0.01],IgAN组与非肾炎组比较,前者均显著高于后者。HS对IgAN组J链mRNA阳性IgA细胞的SI显著高于非肾炎组(P均<0.01)。(4)HS对CD4 CD25 细胞的SI与对分泌J链IgA细胞的SI呈显著性负相关(P均<0.01)。结论:IgAN患者扁桃体CD4 CD25 细胞减少和分泌J链IgA细胞增多可能与IgAN的发病机制有关。     

异基因骨髓间充质干细胞对类风湿关节炎患者淋巴细胞的影响

目的 探讨在体外环境中,异基因骨髓间充质干细胞(BMSCs)对类风湿关节炎(RA)患者T、B淋巴细胞的增殖和功能成熟的影响.方法 采集健康供者的骨髓标本,经密度梯度离心分离、纯化获得其BMSCs,进行体外培养扩增.同时采集RA患者的外周血,分离单个核细胞.将来源于健康供者的BMSCs与来源于RA患者的单个核细胞在体外进行共培养,同时分别加入T淋巴细胞和B淋巴细胞刺激物.分别检测异基因BMSCs对RA患者T、B淋巴细胞增殖的影响;正常BMSCs对RA患者T淋巴细胞增殖周期和凋亡的影响;BMSCs对RA患者外周血T淋巴细胞CD3、CD4、CD8、CD25表达的影响;以及BMSCs对B细胞分泌IgG的影响.结果 正常骨髓来源的BMSCs对RA患者T、B淋巴细胞增殖均有抑制作用,并且这种抑制作用与BMSCs的剂量呈依赖性;与BMSCs共培养组的T细胞主要处于G0/G1期,而进入细胞增殖周期的细胞比例减少,同叶与BMSCs共培养组的凋亡比例(15.2±0.6)%明显低于单纯T细胞活化组(28.2±1.8)%;与BMSCs共培养后CD3+CD4+T细胞表达阳性率(34±6)较对照组(44±7)降低(P<0.05),CD25+的表达下降,但CD4+CD25+调节性T细胞数(4.9±2.3)增加(P<0.05).在SAC刺激下,健康人BMSCs与RA患者外周血淋巴细胞共培养后IgG分泌升高.结论 异基因BMSCs对RA患者T、B淋巴细胞的增殖和功能成熟均有影响,BMSCs可能在RA发病和病情进展中起一定的作用,同时证明利用MSCs来调节RA的免疫功能紊乱进行生物治疗是可行的.     

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。     

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.