不同剂量的地塞米松对大鼠缺血再灌注心肌细胞凋亡及核因子кB表达的影响

目的探讨不同剂量地塞米松预处理对大鼠缺血再灌注(I/R)心肌细胞凋亡及NF-κB表达的影响。方法 64只SD大鼠,随机分为大剂量组、中剂量组、小剂量组及对照组,每组1 6只,分别予2.5、0.8和0.4 mg/kg的地塞米松及蒸馏水预处理。预处理24 h后,构建体外心脏I/R模型,观测缺血前期及再灌注期左心室发展压(LVDP)、左心室压力最大上升和下降速率(±dp/dt_(max))、冠状动脉流出量(CF);测冠状动脉流出液肌酸磷酸激酶同工酶(CK MB)漏出率;TUNEL法检测心肌细胞凋亡;免疫组织化学法检测NF-κB活化水平。结果与对照组比较,大、中剂量组LVDP、±dp/dt_(max)及CF明显改善(P<0.05),CK-MB漏出率明显降低(P<0.05),心肌细胞凋亡指数及NF-κB表达明显减少(P<0.01);小剂量组上述指标虽有改善,但差异无统计学意义(P>0.05)。结论地塞米松预处理对大鼠I/R的心肌保护作用可能与抑制NF-κB活性,减少心肌细胞凋亡有关,且有一定的剂量依赖性。     

地塞米松对大鼠心肌缺血再灌注后细胞凋亡及金属硫蛋白表达的影响

目的观察地塞米松预处理对大鼠心肌缺血再灌注损伤的影响并探讨其作用机制。方法32只SD大鼠随机分成地塞米松组(16只)和对照组(16只),分别给予地塞米松(0.8mg/kg)和蒸馏水腹腔注射。预处理24h后,构建体外心脏缺血再灌注动物模型,动态观测缺血前期及再灌注期左心室发展压(LVDP)、左心室压力最大上升和下降速率(±dp/dtmax)、冠状动脉流出量(CF);测定冠状动脉流出液肌酸激酶同工酶(CK-MB)的漏出率;TUNEL法检测心肌细胞凋亡;Westernblot法检测金属硫蛋白(MT)、Bcl-2及Bcl-xl蛋白的表达;免疫组织化学法测定半胱天冬酶-3(caspase-3)的水平。结果与对照组比较,地塞米松组大鼠再灌注期LVDP、±dp/dtmax及CF得到改善(P<0.05);CK-MB的漏出率明显降低[(8.69±4.16)U/gvs(18.15±5.59)U/g,P<0.01];心肌细胞凋亡指数(10.18±1.99)%vs(14.66±2.97)%和caspase-3水平明显减少[(18.66±5.15)%vs(27.93±6.23)%,P<0.01],Bcl-xl(4.74±0.66)vs(1.69±0.73)和MT的表达明显增加[(3.09±1.07)vs(1.03±0.02),P<0.05],Bcl-2无明显变化(P>0.05)。结论地塞米松预处理对大鼠缺血再灌注的心肌具有保护作用,上调MT表达及抑制细胞凋亡可能是其机制之一。     

地塞米松对大鼠缺血再灌注心肌细胞凋亡及HSP72、NF-κB表达的影响

目的探讨地塞米松预处理对大鼠缺血再灌注（I/R）心肌细胞凋亡及热休克蛋白72（HSP72）、核因子κB（NF-κB）表达水平的影响。方法SD大鼠随机分成地塞米松组和对照组,分别予地塞米松和生理盐水预处理。预处理后构建Langendorff离体心脏I/R动物模型,测定冠状动脉流出液肌酸激酶MB同工酶（CK-MB）的漏出率及观察心肌超微结构的变化;原位末端标记（TUNEL）法检测心肌细胞凋亡;Western印迹法检测HSP72表达;免疫组化法检测NF-κB的活化水平。结果与对照组相比,地塞米松组冠状动脉流出液CK-MB的漏出率降低（P〈0.05）;超微结构的损伤减轻;细胞凋亡指数及NF-κB表达减少（P〈0.01）,HSP72表达增加（P〈0.05）。结论地塞米松上调心肌HSP72及下调NF-κB表达可能与其抑制I/R心肌细胞凋亡有关。     

丙酮酸乙酯对大鼠心肌细胞凋亡及NF-κB表达的影响

应用Langendorff主动脉逆行灌流方法建立体外大鼠缺血再灌注（I/R）心脏模型,将24只雄性大鼠随机分为3组每组各8只.对照组K-H液持续灌流120 min;I/R组平衡灌流30 min,全心停灌30 min,再灌60 min;丙酮酸乙酯组（EP组）实验程序与I/R组相同,平衡15 min后和再灌注期间灌流使用含2 mmol/LEP的K-H液.检测心肌MDA含量,分别以缺口末端标记法（TUNEL法）及免疫组化法检测心肌细胞凋亡指数（AI）和核因子-κB转录（NF-κB）蛋白表达的变化.I/R组MDA含量,AI和NF-κB表达水平均明显高于对照组和EP组（P均＜0.05）.EP可抑制I/R后心肌细胞凋亡,此作用可能与其减轻氧化应激、减少I/R心肌组织过度表达NF-κB有关.     

胡黄连苦苷Ⅱ在心肌缺血再灌注损伤中的保护作用及机制

目的:探讨胡黄连苦苷Ⅱ(picroside-Ⅱ,P-Ⅱ)对心肌缺血再灌注(ischemia/reperfusion,I/R)损伤的保护作用及其对TLR4/NF-κB信号通路的影响。方法:30只成年雄性SD大鼠随机分为3组:假手术组(SO组)、缺血再灌注组(I/R组)、胡黄连苦苷Ⅱ+缺血再灌注组(P-Ⅱ+I/R组)。P-Ⅱ+I/R组术前30min给予胡黄连苦苷Ⅱ(25mg/kg)尾静脉注射。除SO组外,其余2组大鼠均行冠状动脉左前降支结扎30min再灌注4h,建立心肌I/R损伤模型;使用试剂盒检测乳酸脱氢酶(LDH)、肌酸激酶(CK)的水平;HE染色观察心肌组织病理改变;TUNEL染色观察心肌细胞凋亡并计算凋亡率;蛋白免疫印迹法检测TLR4、NF-κB及IL-6和TNF-α的表达。结果:胡黄连苦苷Ⅱ预处理可显著降低LDH和CK的水平及心肌细胞凋亡率,差异有统计学意义(P0.05);同时,缺血再灌注损伤中明显上调的TLR4、NF-κB以及IL-6、TNF-α蛋白表达水平均显著降低,差异有统计学意义(P0.05)。结论:胡黄连苦苷Ⅱ能够减轻大鼠心肌I/R损伤,这种保护作用可能与其抑制TLR4/NF-κB炎症信号通路密切相关。     

大蒜素通过调节Bcl-2,Bax及NF-κB表达而抑制大鼠缺血/再灌注心肌细胞凋亡(英文)

目的:探讨大蒜素预处理对在体大鼠心肌缺血/再灌注(I/R)损伤的保护作用、对心肌细胞凋亡的影响及Bcl-2,Bax,NF-κB是否参与抗凋亡作用。方法:建立大鼠在体心肌I/R损伤模型,将48只大鼠随机分为正常对照(Con)组、I/R组和大蒜素预处理(AP)组;各组均测定心肌梗死范围[IS/AAR(%),TTC法]、再灌注后血清肌酸磷酸肌酶同工酶MB(CK-MB)和超氧化物歧化酶(SOD)活性,并应用DNA琼脂糖凝胶电泳及TUNEL法检测各组凋亡指数(AI)、Bcl-2,Bax表达及NF-κB核结合活性。结果:AP组较I/R组IS/AAR(%)[(21.8±1.5)%vs.(44.6±4.6)%,P0.01],CK-MB[(16.4±1.6)vs.(34.1±1.8)U/L,P0.01]明显降低,SOD[(2 337±215)vs.(1 219±187)U/mg pro,P0.01]明显增高。AP组AI较I/R组明显降低[(7.0±1.2)%vs.(4.0±3.0)%,P0.01]。Bcl-2表达明显增加,Bax表达明显减少,NF-κB核结合活性明显降低。结论:大蒜素有明显抗大鼠心肌I/R损伤作用能与抗心肌细胞凋亡有关,对Bcl-2,Bax及NF-κB表达的调控起重要作用。     

急性心肌缺血再灌注犬心肌组织NF-κB的表达与瑞芬太尼的干预作用

目的 观察急性心肌缺血再灌注犬心肌组织NF-κB的表达及瑞芬太尼预处理对NF-κB表达的影响.方法 健康杂种犬18只,随机分为:假手术组(S组)、缺血再灌注组(I/R组)、瑞芬太尼预处理组(RPC组).S组犬开胸后在冠状动脉左前降支下穿线不结扎;I/R组犬开胸后结扎冠状动脉左前降支,缺血30 min再灌注2 h;RPC组为缺血前以1 pg／(kg·min)微泵输注瑞芬太尼30 min进行预处理,余同I/R组.再灌注2 h时处死犬取心肌组织,免疫组化法检测心肌组织NF-κB的表达情况.结果 I/R组、RPC组与S组相比,心肌组织NF-κB含量显著升高(P<0.05),RPC组与I/R组比较,心肌组织NF-κB的表达降低(P<0.05).结论 急性心肌缺血再灌注犬心肌组织NF-κB的表达显著增强,瑞芬太尼预处理可降低再灌注2 h时心肌组织NF-κB的表达.     

白藜芦醇对大鼠缺血心肌的保护及对凋亡的抑制作用

目的 探讨白藜芦醇对大鼠缺血再灌注心肌的保护及对心肌细胞凋亡的影响,并分析与PI3K-Akt信号通路的关系.方法 50只成年雄性SD大鼠,随机分为5组,即假手术组(SH组)、缺血再灌注组(I/R组)、白藜芦醇预处理组(Res组)、白藜芦醇预处理+渥曼青霉素组(Res+Wom组)、缺血再灌注+渥曼青霉素组(I/R +Wom组);结扎冠状动脉左前降支制备心肌缺血模型;监测血流动力学,记录左心室收缩压(LVSP)、左室舒张末期压(LVEDP)、左心室变化速率最大值(±dp/dtmax)在缺血前、缺血30 min、再灌注60、90、120 min等几个时间点的变化情况,并同步监测肢体Ⅱ导联心电图;测定再灌注心肌组织中一氧化氮合酶(NOS)、一氧化氮(NO)的含量,并用TUNEL方法测定细胞凋亡,免疫组化测定心肌组织中Bcl-2、Bax蛋白的表达,利用Western印迹测定蛋白激酶B(又称PKB)及磷酸化蛋白激酶B(P-Akt)含量.结果 与I/R组及Res+ Wom组比较,Res组NOS及NO表达增加,显著减轻心肌细胞凋亡,Bcl-2蛋白表达显著升高,Bax/Bcl-2降低,Res组P-Akt蛋白表达明显增加(P＜0.05).结论 白藜芦醇对缺血而再灌注心肌有较好的保护作用,能够抑制再灌注所引起的细胞凋亡,其作用机制可能与PI3K-A kt信号通路活化有关.     

阿托伐他汀对心肌缺血再灌注老年大鼠NF-κBp65、COX-2表达的影响

目的 探讨阿托伐他汀对心肌缺血再灌注老年大鼠NF-κBp65、COX-2表达的影响.方法 健康Wistar老年大鼠30只,18月龄,随机分为3组,假手术组(S组)、缺血再灌注组(I/R组)、阿托伐他汀组(AT组),每组10只.采用结扎左冠状动脉前降支制备心肌缺血再灌注模型.观察阿托伐他汀对缺血再灌注老年大鼠血清中肌酸激酶同工酶(CK-MB)、天门冬氨基转移酶(AST)、乳酸脱氢酶(LDH)溢出量的影响;采用免疫组化法观察心肌缺血再灌注后心肌组织细胞中NF-κBp65及COX-2的蛋白表达.结果 与S组比较,I/R组心肌组织中CK-MB、AST及LDH含量明显增高,NF-κBp65的活性增高,COX-2的蛋白表达明显增加均有统计学意义(P ＜0.001);AT组中CK-MB、AST及LDH含量、NF-κBp65及COX-2略升高均有统计学意义(P＜0.01).结论 CK-MB、AST、LDH的含量及NF-kBp65和COX-2在心肌缺血再灌注中均有高水平表达,提示炎症参与了心肌缺血再灌注,机制可能是NF-κBp65通过对COX-2的转录调控发挥了重要作用;阿托伐他汀可抑制NF-κBp65活性,降低COX-2的蛋白表达水平,减轻I/R心肌炎症反应,对心肌起保护作用.     

龙血竭总黄酮对新西兰兔心肌缺血/再灌注损伤作用的研究

目的研究龙血竭总黄酮对新西兰兔心肌缺血/再灌注损伤的保护作用。方法将30只新西兰兔随机分为三组,每组10只。采用结扎新西兰兔左冠状动脉前降支法,建立心肌缺血/再灌注损伤模型。观察心肌组织HE染色的结构变化,测量左心室内压最大上升速率(+dp/dtmax),检测心肌肌酸激酶同工酶(CK-MB)。结果龙血竭处理组心肌组织结构明显好于缺血/再灌注组;缺血/再灌注组和龙血竭处理组+dp/dtmax均明显低于假手术组(P0.01),龙血竭处理组+dp/dtmax高于缺血/再灌注组(P0.01);缺血/再灌注组CK-MB水平明显高于假手术组(P0.01),龙血竭处理组CK-MB水平高于假手术组(P0.05),并低于缺血/再灌注组(P0.01)。结论龙血竭总黄酮能够改善心肌缺血/再灌注损伤,保护心肌组织结构,稳定细胞膜结构,减少心肌CK-MB漏出,提高缺血/再灌注损伤模型心肌的收缩功能。     

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.