内镜模拟训练在上消化道内镜培训中的作用研究

目的 探讨内镜模拟训练在上消化道内镜教学中的作用.方法 2005年1月-2007年3月41名无内镜操作经验的进修医师、研究生、住院医师,随机分为两组.非内镜模拟训练组于内镜中心观摩学习1个月后开始操作内镜,内镜模拟训练组于观摩学习的同时接受10 h的内镜模拟训练.由专人对所有受训者最初20例内镜操作进行评价、记录,包括插入食管是否成功、胃内观察是否成功、通过幽门是否成功、进入降段是否成功、总的操作时间.结果 插入食管成功率、进入降段成功率两组间差异无统计学意义;胃内观察成功率(P<0.001)、通过幽门成功率(P<0.001)、总操作时间(P=0.032),内镜模拟训练组均优于非内镜模拟训练组,两组间差异有统计学意义.结论 内镜模拟训练在上消化道内镜教学中有重要作用,有助于受训者迅速掌握内镜操作方法,缩短教学时间,减少患者痛苦.     

常规内镜窄带内镜全结肠色素内镜及全结肠醋酸喷洒对结肠病变发现率的对比研究,

目的 比较常规内镜与窄带内镜(NBI)、全结肠色素内镜及全结肠醋酸喷洒对结肠病变的发现率.方法 选择2006年4月至6月就诊于首都医科大学附属北京友谊医院消化内科准备接受结肠镜检查的患者240例.用随机数字表法将患者分为4组其中常规内镜组61例、NBI组63例、全结肠色素内镜组54例、醋酸染色组62例.观察各组间扁平及隆起病变部位、数量,并且对各组间操作时间、患者痛苦评分及检查费用进行比较.结果 在4组中,共发现233枚病变,其中扁平病变90枚(38.6%),隆起病变143枚(61.4%).扁平病变常规内镜共发现18枚(29.5%),而全结肠靛胭脂染色组发现32枚(59.3%)病变,差异有统计学意义(P＜0.05).隆起病变常规内镜共发现22枚(36.1%),而全结肠醋酸染色组发现55枚(88.7%)病变,差异有统计学意义(P＜0.01).但是与常规内镜相比,窄带内镜、全结肠色素内镜及全结肠醋酸喷洒染色对于结肠腺瘤及癌变的诊断数量及诊断率没有提高.与常规内镜组相比,除操作时间有所延长外,其余3组患者痛苦程度及费用都没有明显差别(P＞0.05).结论 全结肠色素内镜及全结肠醋酸喷洒可提高结肠病变的发现率,前者可以提高扁平病变的发现率,后者可提高隆起病变的发现率.     

OMOM胶囊内镜在无症状人群体检中的应用

目的 探讨OMOM胶囊内镜在无症状人群体检中应用价值.方法 受检者为2005年8月-2010年3月到北京军区总医院消化内科进行胶囊内镜检查的无症状体检人群,受检者按就诊的时间顺序随机分为研究组(A组)、对照组(B组)、自身对照组(C组).A组受检者按一定体位进行胶囊内镜检查,送服胶囊后立即依次平卧位3 min,左侧卧位3 min,右侧卧位3 min,半卧位3min,观察食管黏膜情况,再观察胃依次左侧卧位10 min,平卧位10 min,右侧卧位10 min,站立位10 min,随后可自由活动,直至胶囊内镜排出体外.B组受检者按常规要求进行胶囊内镜检查.C组受检者进行胶囊内镜检查后即安排胃镜和结肠镜检查.结果 A组和B组胶囊内镜食管运行平均时间和胃排空平均时间差异均有统计学意义(P＜0.05);但A组和B组胶囊内镜排出平均时间差异无统计学意义(P＞0.05).A组和C组胶囊内镜食管运行平均时间和排出平均时间差异均有统计学意义(P＜0.05);但A组和C组胶囊内镜胃排空平均时间差异无统计学意义(P＞0.05).90例A组受检者中检出消化道病变者28例,检出率31.11％;160例B组受检者中检出消化道病变者42例,检出率26.25％;110例C组受检者中检出消化道病变者43例,检出率39.09％.A组和B组食管病变检出率比较差异具有统计学意义(P＜0.05).结论 胶囊内镜在特定体位下可以提高食管及胃病变检出率.胶囊内镜检查可以指导胃镜及结肠镜检查能更有效提高消化道疾病检出率,用于无症状人群体检无疑是一种安全、无创、无痛苦的消化道检查方法.     

右心结构改变与心电图V1导联P波终末电势的关系

目的:应用超声心动图检查,分析右心结构改变与心电图上V1导联P波终末电势(ptfV1)的关系.方法:对52例同时行心电图及超声心动图检查的病例进行分析.结果:右心房心尖四腔短径、右心室心尖四腔长径ptfV1值即P波直立组、ptfV1＞-0.03 mm·s组、ptfV1≤-0.03 mm·s组三个组间比较,差异有统计学意义(P＝0.001,表2);但各组间LSD法检测P波直立组与ptfV1＞-0.03 mm·s组之间比较差异无统计学意义(P＞0.05).右心室短轴流出道内径ptfV1值即P波直立组、ptfV1≤-0.03 mm·s组、ptfV1＞-0.03 mm·s组三个组间比较,差异有统计学意义(P<0.05);但各组间LSD法检测P波直立组与ptfV1＞-0.03 mm·s组比较,差异无统计学意义(P＞0.05).肺动脉主干内径、右心房心尖四腔长径、左心室长轴观右心室前后径及右心室心尖四腔短径在P波直立组、ptfV1≤-0.03 mm·s组、ptfV1＞-0.03 mm·s组三个组间比较差异均无统计学意义(P＞0.05);各组间LSD法检测差异均无统计学意义(P＞0.05).结论:心电图ptfV1的出现与右心结构变化有一定关系.     

不同年龄层不明原因消化道出血患者胶囊内镜诊断结果分析

目的 对不明原因消化道出血患者的胶囊内镜(CE)检查结果进行分析,总结不同年龄层患者的病变特点.方法 收集我院2006年12月～2010年2月间符合纳入标准的患者163例,采集患者信息并分析病变特点.结果 163例患者中,老年组患者检出率高于青年组和中年组,差异有统计学意义(P＜0.01);不同年龄组患者检出病变类型分布比较,差异有统计学意义(P＜0.05),青年组以肿物为主;中年组以溃疡、血管畸形为主;老年组以血管畸形为主.结论 各年龄组间的检出率和诊断率比较差异有统计学意义(P＜0.05),提示CE检查对老年组患者的不明原因消化道出血有更好的检出率.     

医用一次性便携式内镜上消化道检查的动物实验研究

目的评价自主研制的医用一次性便携式内镜(YunSendo)应用于巴马小型猪上消化道内镜检查的安全性、可行性和操作性能。方法广西巴马小型猪10只,先用活检钳在模型猪上预先制备食管、胃、十二指肠黏膜损伤模型。每只实验动物由2名内镜医师分别完成医用一次性便携式内镜和奥林巴斯内镜(GIF-Q260J型)检查。记录到达十二指肠时间,发现上消化道各部位黏膜损伤数目,规范采集不同部位的内镜图像,评价内镜操作性能和内镜图像质量。不同医师均采用盲法记录各自实验结果,2种内镜检查顺序通过执硬币法决定。采用配对t检验进行统计学比较。结果医用一次性便携式内镜操作组与奥林巴斯内镜操作组进镜时间和操作总时间比较[(171.00±9.96) s比(164.00±17.84) s、(285.00±33.94) s比(273.40±23.46) s]差异均无统计学意义(t=1.289、1.281,P=0.230、0.232);医用一次性便携式内镜操作组与奥林巴斯内镜操作组进镜过程和操作全程的视野清晰时间百分数比较[(91.83±1.85)%比(91.52±1.51)%、(93.07±3.10)%比(92.06±2.57...     

80岁以上高龄总胆管结石患者内镜下括约肌切开术治疗安全性探讨

目的 探讨对80岁以上高龄总胆管结石患者进行内镜下括约肌切开术(EST)治疗的安全性.方法 对2005-2007年进行EST治疗的总胆管结石患者,选择其中≥80岁的148例作为高龄组; ≤60岁的745例作为对照组.比较两组患者的临床资料与手术成功率及手术后的并发症.结果 ①高龄组和对照组伴随疾病发生率为29.3%和8.1%,两组间差异有统计学意义(P＜0.01);有前期胆道手术或内镜逆行胰胆管造影术史者分别为45.18%和21.3%,两组差异有统计学意义(P<0.01).②高龄组EST成功率为95.6%,对照组为96.5%,两组间差异无统计学意义(P＞0.05).③高龄组术后并发症共16例(10.8%),其中EST本身并发症13例(占8.8%);3例并发症与EST有关(占2%),1例死于吸入性肺炎.对照组术后发生EST本身并发症共41例(5.5%),未发生EST相关并发症.两组间EST本身的并发症发生率差异无统计学意义(P＞0.05),但与EST有关的并发症发生率差异有统计学意义(P＜0.01).④术后平均住院时间,高龄组为(7.2±2.2)d,对照组为(5.1±1.4)d,两组间差异无统计学意义(P＞0.05).结论 对于80岁以上高龄总胆管结石患者,EST仍然是安全有效的治疗手段.     

高龄患者行治疗性内镜逆行胰胆管造影的安全性和有效性探讨

[目的]探讨治疗性内镜逆行胰胆管造影(endoscopic retrograde cholangiopancreatography,ERCP)在高龄患者中应用的有效性和安全性。[方法]将行治疗性ERCP操作的患者169例,按年龄分组,其中≥70岁83例(高龄组),70岁86例(非高龄组);记录2组患者ASA分级、基础疾病、ERCP操作以及并发症情况,对结果进行统计分析、比较2组患者治疗性ERCP的应用情况,[结果]169例患者进行了181次治疗性ERCP操作。2组间例数、性别比例均差异无统计学意义(P0.05),高龄组患者ASA分级、胆道系统结石及胰腺或胆道恶性肿瘤发生率均显著高于非高龄组(P0.05);治疗性ERCP后2组操作成功率、并发症发生率均差异无统计学意义(P0.05)。[结论]高龄组进行治疗性ERCP操作的疗效与非高龄组一致,治疗性ERCP在高龄患者中的应用是安全、有效的。     

左侧卧位I-scope气管插管优化内镜黏膜下剥离术前麻醉时间的临床研究

目的 探讨左侧卧位I-scope气管插管用于内镜黏膜下剥离术（ESD）能否优化术前麻醉时间。方法 2018年3—12月于首都医科大学附属北京友谊医院拟行ESD的150例早期胃食管癌患者纳入研究,根据SPSS 20.0随机数字分为3组,每组50例。SL组患者左侧卧位,使用I-scope气管插管;SS组患者平卧位,使用I-scope气管插管;MS组患者平卧位,Macintosh喉镜直接气管插管。主要观察术前非必需麻醉时间（气管插管成功后至内镜手术开始的间隔时间）、气管插管成功的插管次数、相关并发症等并行统计分析。结果 SL组的术前非必需麻醉时间为（8.55±2.16）min,SS组为（10.44±2.43）min,MS组为（10.56±3.20）min,3组间差异有统计学意义（F=9.08,P＜0.001）,SL组明显少于SS组（P＜0.001）和MS组（P＜0.001）,SS组与MS组间差异无统计学意义（P=0.819）。SL组的一次气管插管成功率为96.0%（48/50）,SS组为90.0%（45/50）,MS组为92.0%（46/50）,3组间比较差异无统计学意义（χ2=2.601,P=0.627）。患者术后清醒拔除气管导管恢复至返病房期间的咳嗽咳痰、口干、黏膜损伤发生率,3组间比较差异均无统计学意义（P均＞0.05）;咽痛发生率3组间比较差异有统计学意义（χ2=7.175,P=0.028）,MS组（38.0%,19/50）高于SL组（18.0%,9/50,P＜0.05）和SS组（18.0%,9/50,P＜0.05）,SL组与SS组间差异无统计学意义（P＞0.05）。结论 左侧卧位I-scope气管插管用于ESD能有效优化术前麻醉时间。     

短段Barrett’s食管的不同组织类型、内镜形态、异型程度与Cyclin D1、P53表达的相关性研究

目的研究细胞周期蛋白D1(Cyclin D1)、P53蛋白在短段Barrett’s食管(short segment Barrett’s esophagus,SSBE)不同组织类型、不同内镜形态、不同异型程度分组中的表达,预测不同类型SSBE上皮癌变的风险性,准确筛选高危人群,为指导制定内镜随访计划提供依据。方法选取经电子胃镜、病理检查确诊为SSBE的患者51例,另取32例正常食管黏膜组织作为对照。再根据SSBE不同内镜下形态分为全周型16例、舌型13例、岛型22例,根据不同病理组织类型分为胃底型20例、贲门型21例、特殊肠化型10例,根据BE组织异型增生的程度分为无异型增生组37例、轻度异型增生组14例、重度异型增生组0例。采用免疫组化法检测不同亚组细胞Cyclin D1和P53蛋白的表达,并进行统计学分析。结果 Cyclin D1、P53在SSBE组及正常食管黏膜组中的表达均较低,差异无统计学意义(P0.05)。Cyclin D1、P53在SSBE不同内镜下形态分型、不同组织学分型各亚组中的表达差异均无统计学意义(P0.05)。Cyclin D1、P53在合并异型增生组中均表达升高,Cyclin D1在无异型增生、轻度异型增生组中的表达阳性率分别为21.6%、64.3%,组间差异有统计学意义(P=0.007);P53在无异型增生、轻度异型增生组中的表达阳性率分别为27.0%、71.4%,组间差异有统计学意义(P=0.006)。结论 SSBE总体癌变风险低。SSBE的癌变风险与内镜形态分型及组织学分型的不同无直接相关性。对合并异型增生者,Cyclin D1和P53的表达明显升高,提示SSBE伴异型增生者癌变风险明显增加。     

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.