厄贝沙坦对大鼠心肌缺血再灌注细胞凋亡与细胞外信号调节激酶通路的影响

目的观察厄贝沙坦对大鼠缺血再灌注心肌细胞凋亡的影响,并探讨其与细胞外信号调节激酶(ERK)通路的关系。方法健康雄性SD大鼠72只,随机分为假手术组、缺血再灌注组、缺血预处理组、厄贝沙坦组、厄贝沙坦+PD-98059组(PD组)。厄贝沙坦灌胃1周后制作大鼠心肌缺血再灌注模型,PD-98059于缺血前15 min尾静脉注射。实验结束后用TTC染色测定心肌梗死面积;免疫组织化学法检测心肌组织BcI-2、Bax表达;Western blot法测定磷酸化ERK的活性;TUNEL检测凋亡细胞指数。结果与假手术组比较,缺血再灌注组、缺血预处理组、厄贝沙坦组、PD组心肌细胞凋亡指数、磷酸化ERK活性及Bcl-2、Bax表达明显增加(P<0.01);与缺血再灌注组比较,缺血预处理组、厄贝沙坦组心肌梗死面积、心肌细胞凋亡指数和Bax表达明显降低,磷酸化ERK活性及Bcl-2表达明显增加(P<0.01);与厄贝沙坦组比较,缺血再灌注组、PD组心肌梗死面积、心肌细胞凋亡指数和Bax表达明显增加,磷酸化ERK活性及Bcl-2表达明显降低,差异有统计学意义(P<0.01)。结论厄贝沙坦能够激活ERK通路,进一步调控Bcl-2、Bax蛋白的表达,抑制再灌注心肌细胞的凋亡。     

中药复方冠心康对大鼠缺血再灌注损伤心肌细胞Bcl-2、Bax表达的影响

目的观察中药复方冠心康对大鼠缺血再灌注损伤(MIRI)心肌细胞相关凋亡因子Bcl-2、Bax表达的影响。方法 40只SD雄性大鼠随机分为假手术组、MIRI模型组、冠心康组、盐酸地尔硫卓组。采用结扎左冠状动脉前降支30min,再灌注2h复制大鼠MIRI模型,分别以HE染色、TUNEL法及免疫组织化学法检测心肌组织病理学、心肌细胞凋亡指数、心肌细胞Bcl-2、Bax的阳性表达。结果 MIRI组与假手术组比较心肌细胞凋亡指数值显著升高(P<0.01),而冠心康组明显降低(P<0.01);抑凋亡因子Bcl-2在MIRI后表达明显降低,而促凋亡因子Bax表达则明显升高,冠心康可明显升高Bcl-2的表达,同时降低Bax的表达(P<0.01)。结论中药复方冠心康对大鼠MIRI心肌细胞具有明显的保护作用,其作用机制与调控心肌细胞的凋亡因子Bcl-2、Bax的表达有关。     

依那普利对心力衰竭大鼠心肌细胞凋亡及凋亡基因bcl-2、Bax的影响

目的:探讨血管紧张素转化酶抑制剂(ACEI)———依那普利对慢性压力负荷性心力衰竭大鼠心肌重构、心肌细胞凋亡、凋亡基因Bcl 2、Bax在心肌细胞中表达的影响,为心力衰竭的发病机制及治疗提供实验依据。方法:结扎大鼠的腹主动脉,复制慢性压力负荷性心力衰竭模型,32只大鼠随机分为心力衰竭组 12 只、依那普利治疗组(治疗组)12只、对照组8只。手术后6周,充血性心力衰竭模型形成。治疗组给予依那普利10 mg·kg-1·d-1灌胃,心力衰竭组和对照组给予同量0.85%氯化钠溶液灌胃。在 3 个月末测量血流动力学指标后,将大鼠处死,取出心脏。用原位脱氧核糖核酸酶末端标记法(TUNEL)检测细胞凋亡;免疫组化法和免疫印迹法测 bcl 2、Bax表达。结果:心力衰竭组与对照组相比,心功能明显减退(P < 0.01);心肌细胞凋亡明显增加(P <0.01);在心肌细胞中bcl 2 表达减低,Bax表达增加。依那普利治疗后能改善心室重构(P<0.05),减少心肌细胞凋亡(P< 0.01),增加bcl 2、减少Bax在心肌细胞中的表达(P<0.05)。结论:在心力衰竭时血管紧张素Ⅱ生成增多,减低bcl 2的表达,增加Bax的表达,从而降低 bcl 2/Bax比率;依那普利可能通过血管紧张素Ⅱ的介导作用,增加bcl 2、减低Bax在心肌细胞中的表达,减轻心肌细胞凋亡。     

醛固酮诱导大鼠心肌细胞凋亡及天然VitE干预的影响

将32只大鼠随机分为对照组(C组)、醛固酮组(A组)、醛固酮 天然VitE组(E组)和醛固酮 螺内酯组(S组).比较各组大鼠间心肌组织匀浆超氧化物歧化酶(SOD)和丙二醛(MDA)含量,心肌细胞凋亡指数(AI),以及Bax和Bcl-2的表达.发现与C组比较,A组AI、Bax、MDA明显增加,Bcl-2、SOD明显减少;与A组比较,E组和S组MDA、AI和Bax均明显减少,Bcl-2、SOD明显增加.认为天然VitE能够改善醛固酮诱导的心肌细胞凋亡,其作用机制与改善醛固酮诱导的心肌组织氧化应激水平,抑制促凋亡基因Bax表达和上调抑凋亡基因Bcl-2表达有关.     

银杏叶提取物对大鼠急性心肌缺血再灌注时心肌细胞凋亡及凋亡相关基因表达的影响

目的 探讨银杏叶提取物(EGB)对大鼠心肌缺血再灌注时心肌细胞凋亡及凋亡相关基因表达的影响.方法 采用结扎左冠状动脉前降支(LAD)30 min,再灌注2 h复制大鼠心肌缺血再灌注模型,分别以缺口末端标记法(TUNEL)及免疫组织化学法检测心肌凋亡细胞、心肌细胞Bcl-2、Bax基因的蛋白表达的变化.结果 缺血再灌注(IR)组心肌细胞凋亡数量显著高于假手术组(P<0.01),EGB组心肌细胞凋亡明显受到抑制(P<0.01).IR组和EGB组Bax、Bcl-2、P53基因蛋白表达均明显增加(P<0.01);EGB明显促进Bcl-2基因表达,同时抑制Bax、P53基因表达(P<0.01),Bcl-2和Bax的比值也随之升高.结论 EGB可明显下调Bax和P53基因的蛋白表达,上调Bcl-2基因的蛋白表达,从而显著抑制心肌缺血再灌注损伤(MIRI)后心肌细胞凋亡.     

依那普利、洛沙坦合用对自发性高血压病鼠心肌细胞bcl-2、Fas蛋白表达的影响

分别用依那普利(依那普利组)、洛沙坦(洛沙坦组)及两者合用(合用组)喂养28只自发性高血压病大鼠(SHR).不喂养任何药物的SHR作为空白对照组.另择Wistar-Kyoto鼠作为对照组.采用免疫组化S-P法检测各组Fas、bcl-2的表达.结果与对照组比较,空白对照组、依那普利组、洛沙坦组Fas升高、bcl-2降低;与空白对照组比较,依那普利组、洛沙坦组及合用药组Fas降低、bcl-2升高.以合用药组为著(P＜0.05,＜0.01).提示,依那普利组、洛沙坦合用较单独用药能更有效地调节SHR心肌细胞的抗凋亡基因与促凋亡基因表达失衡,减少细胞凋亡.     

桂枝加减汤对MRL小鼠心肌细胞凋亡及Bax mRNA、Caspase3mRNA基因表达的影响

目的:探讨复方中药对MRL小鼠心肌细胞凋亡的作用及机理.方法:将MRL小鼠分为复方中药组、桂枝组、强的松组和空白对照组,检测MRL小鼠心肌组织凋亡细胞,计算心肌细胞凋亡指数(AI),RT-PCR法检测心肌细胞凋亡基因Bax mRNA、Caspase 3 mRNA表达,观察复方中药(组成:丹参、桂枝、西洋参、冰片)对MRL小鼠心肌细胞凋亡的影响.结果:复方中药能抑制Bax mRNA、Caspase 3 mRNA表达,明显抑制心肌细胞凋亡(心肌细胞凋亡指数显著下降).其疗效明显优于桂枝组和空白对照组(P<0.05),与强的松组疗效相当,P>0.05.结论:复方中药可能通过调控凋亡基因Bax mRNA、Caspase 3 mRNA表达而抑制心肌细胞凋亡,从而延缓或部分逆转MRL心肌损害的发生、发展.     

缺血后适应对大鼠移植心脏心肌细胞凋亡的影响

目的:观察缺血后适应对大鼠移植心脏缺血再灌注时心肌细胞凋亡及对抗凋亡基因Bcl-2(简称Bcl-2)、凋亡基因Bax(简称Bax)蛋白表达的影响。方法:30只Lewis大鼠随机分成3组,每组10只,供体、受体各5只。假手术组:仅行腹部开关手术,不行心脏移植;模型组:行心脏移植术;后适应组:行心脏移植手术,心脏复灌前进行缺血后适应,即再灌注10 s、关闭10 s,循环3次。实验结束后取心肌标本行生物素切口末端标记法(TUNEL)检测,并采用蛋白免疫印迹(Western Blot)方法检测Bcl-2、Bax蛋白表达。结果:假手术组无心肌细胞凋亡,后适应组心肌细胞凋亡指数明显低于模型组,差异有统计学意义(P<0.01)。Western Blot显示:模型组Bcl-2、Bax蛋白表达水平与假手术组比升高(P<0.05);后适应组Bcl-2蛋白表达水平与模型组相比明显升高(P<0.01),而Bax蛋白表达水平降低(P<0.05),差异均有统计学意义。结论:缺血后适应对大鼠移植心脏缺血再灌注心肌能够上调Bcl-2蛋白表达、下调Bax蛋白表达,并可减少缺血再灌注引起的心肌细胞凋亡。     

Y-27632预处理对心肌缺血再灌注损伤过程中d凋亡的影响研究

目的：探讨Rho激酶抑制剂Y-27623对心肌缺血再灌注损伤(MIRI)中细胞凋亡的影响,以及对丝裂原活化蛋白激酶（Mitogen-activated protein kinase,MAPK）和凋亡相关蛋白表达水平的变化和意义。方法：成年雄性SD大鼠60只, 随机分为4组（n=15）:正常对照组(Sham组) 、缺血再灌注组(ischemia-reperfusion即I/R组) 、Dil组( diltiazem即地尔硫卓组)、Y-27632组。Dil组每日给予地尔硫卓(10mg/kg)灌胃, Y-27632组每日给予Y-27632（5mg/kg）,其余两组给予等体积清水。给药五天后Sham组只穿线,不结扎冠状动脉左前降支,I/R组、Dil组和Y-27632组建立MIRI模型。TUNEL法检测各组心肌凋亡,计算心肌细胞凋亡指数(AI),western blotting 法检测心肌组织中MAPK信号传导途径相关蛋白（p-JNK/ERK/P38）和凋亡相关蛋白（Bcl-2、Bax、Caspase-3和Caspase-9）的表达。结果：相对于Sham组,I/R组AI明显增加（P<0.01）,MAPK信号传导途径和心肌促凋亡相关蛋白（Bax、Caspase-3和Caspase-9）表达显著增加（均为P<0.05）,心肌抗凋亡蛋白Bcl-2表达显著减少（P<0.05）;相对于I/R组,Y-27632治疗组AI明显下降（P<0.01）,与Dil治疗组没有显著差异(P>0.05),Y-27632治疗组MAPK信号传导途径相关蛋白和Bax、Caspase-3和Caspase-9表达均显著降低（P<0.05）,Bcl-2表达显著增加（P<0.05）,与Dil治疗组没有显著差异(P>0.05)。结论：Y-27632通过抑制JNK/ERK/P38的磷酸化,抑制Bax、Caspase-3和Caspase-9的表达,加强Bcl-2的表达,来减少心肌细胞的凋亡,从而减轻心肌缺血再灌注损伤。     

水飞蓟宾对大鼠心肌缺血再灌注损伤后心肌细胞凋亡的影响

目的研究水飞蓟宾(Silibinin,SIL)对大鼠心肌缺血再灌注损伤后心肌细胞凋亡的影响及其机制。方法取100只实验用大鼠随机分为假手术组,模型组和SIL低(100mg/(kg·d))、中(200mg/[kg·d))、高(400mg/(kg·d))剂量预处理组(n=20),术前7d开始灌胃给药;采用结扎冠状动脉30min的方法建立大鼠心肌缺血再灌注损伤模型;再灌注6h后,通过高分辨率超声影像系统检测舒张末期左室内径(IVIDd)和收缩末期左室内径(LVIDs)、短轴缩短率(FS)、射血分数(EF)、每搏输出量(SV);TTC染色法计算心肌梗死面积,TUNEL法观察心肌细胞凋亡状况,RT-PCR法测定心肌组织bcl-2 mRNA、Bax mRNA表达,Western blotting法测定心肌组织caspase-3、NF-kB蛋白表达;比色法测定心肌组织中抗氧化酶活性和丙二醛(MDA)含量。结果与模型组比较,发现经SIL中、高剂量预处理能够显著降低急性心肌梗死大鼠LVIDd并显著提高FS、EF和SV,其中SIL高剂量预处理组LVIDs显著降低;显著降低心肌组织梗死面积,明显改善心肌细胞凋亡状况、显著降低心肌细胞凋亡指数(Apoptosis index,AI),显著上调bcl-2 mRNA表达并下调Bax mRNA表达、显著提高‘bcl-2/Bax比值,显著降低caspase-3、NF-kB蛋白表达量,显著提高抗氧化酶(SOD、CAT)活性并显著降低MDA含量,差异均具有统计学意义(P0.05,P0.01)。结论SIL具有抑制心肌缺血再灌注损伤大鼠心肌细胞凋亡的作用,其机制可能与SIL改善心功能、调节凋亡相关基因和蛋白表达以及抑制氧化应激损伤有关。     

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.     

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.     

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.     

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。     

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.     

Angiographic diagnosis of the degree of serosal invasion of carcinoma of the colon

Angiography using Prostaglandin El^® was performed on 38 patients with carcinoma of the colon in order to diagnose the degree of serosal cancer invasion. The findings at angiography were classified into four groups:1) AG-S3, abnormal change (irregularity and/or encasement) up to marginal vessels; 2) AG-S2, abnormality up to vasa recta; 3) AG-S1, abnormality of penetrating branches of vasa recta within the wall of the colon; and 4) AG-S0, no distinct findings of abovementioned vessels. These angiographic findings were compared with both macroscopic and microscopic serosal cancer invasion. Angiographic diagnosis is in accord with the macroscopic findings in 84.2 percent of cases. Angiographic diagnosis is in accord with the microscopic findings in 32.4 percent of cases. Macroscopic findings confirm the angiographic diagnosis precisely but the conflict with microscopic findings should not be overlooked. This may be the result of inflammatory change, adhesion, and fibrosis around carcinoma of the colon.     

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.