氧化型低密度脂蛋白对内皮细胞不对称二甲精氨酸的影响及卡托普利的干预作用

目的　探讨氧化型低密度脂蛋白 ( o X-LDL)对培养人脐静脉内皮细胞 ( HUVECs)上清液中不对称二甲精氨酸 ( ADMA)浓度的影响及卡托普利的保护作用。方法　采用改良的 Jaffe法培养原代 HUVECs,取生长良好的 3～6代 HUVECs用于实验 ,分为 1空白对照组 :加 DMEM培养液 ;2 ox-L DL组 :分别加入 ox-LDL ( 10 0 mg/L,15 0 mg/L) ;3 o X-LDL+卡托普利组 :同时加入 15 0 mg/L o X-LDL 及卡托普利 ( 5 0 mg/L、10 0 mg/L)共孵 2 4h后 ,分别测定上清液中 ADMA、左旋精氨酸 ( L-arg)、一氧化氮 ( NO)和内皮素 ( ET)的浓度 ,并测定血管紧张素转换酶( ACE)的活性。结果　 ox-L DL组 ADMA、ET的量及 ACE活性增加 ,而 NO的量减少 ,且呈浓度依赖性。卡托普利干预后 ,上清液中 ADMA、ET的浓度减少 ,ACE活性降低 ,NO的量增加 ,而 L -arg水平无明显变化。结论　 ox-L DL通过增加 ADMA导致内皮功能紊乱。卡托普利则能通过减少 ADMA减轻 ox-L DL诱导的内皮细胞代谢功能障碍     

氧化低密度脂蛋白对血管内皮细胞二甲精氨酸-二甲赖氨酸水解酶系统的影响及卡托普利的作用

目的:观察氧化低密度脂蛋白(ox-LDL)对培养的人脐静脉内皮细胞(HUVECs)二甲精氨酸-二甲赖氨酸水解酶(DDAH)活性及表达的影响,以探讨不对称二甲精氨酸(ADMA)代谢机制及卡托普利作用。方法:采用改良的Jaffe法培养原代HUVECs,取生长良好的3～6代HUVECs用于实验,分为①空白对照组:加DMEM培养液;②ox-LDL组:加入ox-LDL(100,150mg/L);③ox-LDL加卡托普利组:同时加入150mg/Lox-LDL及卡托普利100mg/L,共孵24h后,检测上清液中一氧化氮(NO)、内皮素(ET)、一氧化氮合酶(NOS)活性、ADMA含量、反应DDAH酶活性的L-胍氨酸(L-cit)浓度,采用Western blot测定细胞裂解液中DDAH的蛋白表达。结果:ox-LDL条件培养下,内皮细胞的代谢产物ADMA、ET的量均较空白对照组高,而NO的量及NOS的活性减少;L-cit浓度显著降低,且有浓度依赖性,而DDAH的表达无明显变化。卡托普利干预后,AD-MA、ET的量较ox-LDL组降低,NOS活性及NO增加,L-cit浓度明显升高。结论:ox-LDL诱导下,内皮损伤ADMA的增加与DDAH的活性减弱有关,而与DDAH的表达无关。卡托普利通过增加DDAH活性促进AD-MA代谢,使NOS活性增高,抑制ox-LDL对内皮功能的损伤。     

奈必洛尔对非对称性二甲基精氨酸诱导损伤人脐静脉内皮细胞的保护作用研究

目的观察奈必洛尔对非对称性二甲基精氨酸(ADMA)诱导损伤人脐静脉内皮细胞(HUVECs)的保护作用。方法用ADMA16μmol/L培养HUVECs 24 h,不加或加入阿替洛尔20μmol/L、奈比洛尔(5μmol/L、10μmol/L、20μmol/L)预处理1 h。0.25%胰酶消化细胞,获取细胞悬液,离心收集细胞上清液,检测一氧化氮(NO)水平、一氧化氮合酶(NOS)活性。提取HUVECs总RNA,用RT-PCR分析内皮型一氧化氮合酶(eNOS)mRNA表达。结果 ADMA16μmol/L刺激HUVECs 24 h后,上清液NO含量和NOS活性降低,eNOS mRNA表达下调。奈比洛尔可剂量依赖性抑制ADMA所致的上述损伤。阿替洛尔对ADMA诱导的损伤无显著改善。结论奈必洛尔可保护ADMA诱导损伤HUVECs。     

氟伐他汀对人脐静脉内皮细胞游离钙离子水平及内皮型一氧化氮合酶活性的影响

目的:观察氟伐他汀对人脐静脉内皮细胞(HUVECs)游离钙离子水平及内皮型一氧化氮合酶(eNOS)活性的影响及可能机制。方法:体外培养HUVECs,随机分为5组:空白对照组,氟伐他汀(10-8,10-7,10-6,10-5mol/L)组。采用硝酸还原酶法测定细胞上清液中NO含量,液体闪烁计数仪测定L-[3H]-精氨酸和L-[3H]-瓜氨酸的含量,用激光共聚焦扫描显像系统检测内皮细胞内游离钙离子浓度([Ca2 ]i)水平的变化。结果:与空白对照组比较,10-8,10-7,10-6,10-5mol/L氟伐他汀孵育细胞12h后可显著升高HUVECs细胞内eNOS活性,促进NO释放,同时伴有[Ca2 ]i升高,且呈浓度依赖性。另外,10-5mol/L氟伐他汀在0～12h时间段呈时间依赖性增高eNOS活性,作用12h使eNOS活性达到最高(P<0.01)。结论:氟伐他汀呈浓度依赖性升高HUVECseNOS活性和促进NO释放,该作用与其增加内皮细胞内[Ca2 ]i有关。     

沙格列汀对过氧化氢诱导损伤的血管内皮细胞二甲基精氨酸二甲胺水解酶/非对称性二甲基精氨酸/内源性一氧化氮合酶通路影响的研究

目的观察二肽基肽酶-4(DPP-4)抑制剂沙格列汀对过氧化氢(H2O2)诱导损伤的血管内皮细胞二甲基精氨酸二甲胺水解酶/非对称性二甲基精氨酸/内源性一氧化氮合酶(DDAH/ADMA/eNOS)通路的影响。方法以培养人脐静脉内皮细胞株(HUVEC)作为靶细胞,在内皮细胞培养基中加入100μmol/L的H2O2制备细胞损伤模型,以20μmol/L沙格列汀进行干预,观察24~72h,检测细胞上清一氧化氮(NO)含量、ADMA浓度,检测细胞中NOS活性、DDAH活性及DDAH蛋白表达量。结果H2O2作用HUVEC后,细胞上清中NO含量降低,而ADMA浓度增加(P0.05)。细胞中NOS活性、DDAH活性、DDAH-Ⅱ蛋白表达量降低(P0.05);而加入沙格列汀,细胞上清中NO含量升高,ADMA浓度降低(P0.05)。细胞中NOS活性、DDAH活性、DDAH-Ⅱ蛋白表达量升高(P0.05)。结论沙格列汀通过对DDAH/ADMA/eNOS通路的调节作用改善H2O2诱导的内皮细胞NO生成减少。     

预处理对肝脏再灌注损伤大鼠肝组织、血液中NO和ET的影响及意义

目的　探讨预处理对肝脏缺血再灌注损伤大鼠肝组织和血液中一氧化氮 (NO)和内皮素 (ET)含量的影响及意义。方法　建立肝脏 70 %缺血再灌注损伤大鼠模型 ,分为对照组、缺血组、缺血预处理组、L -精氨酸组(L - arg)、Nω-硝基 - N -精氨酸甲酯 (L - NAME)组 ,观察各组肝功能变化 ,检测肝组织和血清中 NO和 ET及透明质酸 (HA)水平。结果　预处理可减轻 NO水平的下降和血浆 ET的升高 ,防止肝功酶的升高 (P<0 .0 5 )。结论　预处理可诱导缺血再灌注损伤大鼠 NO产生增加、ET产生减少 ,进而改善其微循环 ,减少再灌注损伤。     

L-精氨酸对糖尿病兔动脉损伤后内膜增生和内皮功能的影响

目的 :探讨糖尿病动脉损伤后内膜增生的机制和L 精氨酸对内膜增生及内皮功能的影响。方法 :2 8只糖尿病兔和 14只正常兔髂动脉行球囊损伤术后分为对照 (Con)组、糖尿病 (DM)组、L 精氨酸(L arg)组 ( 2 2 5 %L arg溶液饮水 )。术后 4周取髂动脉行图象分析或血管反应性测定 ,同时测定血浆中MDA、SOD和NO含量。结果 :DM组血浆中MDA水平明显低于Con组和L arg组 ,而SOD和NO水平明显降低。DM组内膜面积明显大于对照组 ( 0 2 5 5± 0 0 2 4vs.0 176± 0 0 2 9mm2 ,P <0 0 1) ,而L arg组内膜面积明显小于DM组 ( 0 15 3± 0 0 16,P <0 0 1)。L arg组髂动脉环对乙酰胆碱的舒张反应明显高于DM组。结论 :L arg能改善糖尿病兔的内皮功能 ,抑制动脉损伤后内膜增生     

缬沙坦和卡托普利对缺血再灌注纤溶活性、内皮血管活性物质的影响

目的　探讨缬沙坦和卡托普利对缺血再灌注纤溶活性、内皮血管活性物质的影响。方法　新西兰大白兔 6 0只 ,随机分为五组 ,每组 12只 , 组 :假手术组 , 组 :急性心肌梗死 (AMI)组 , 组 :缺血再灌注 (ischem ic reperfu-sion,IR)组 , 组 :IR+卡托普利组 , 组 :IR+缬沙坦组 ;各组 (除 组外 )分别结扎冠状动脉左心室支中点 ,缺血6 0 min,松开结扎线再灌注 2 4 0 min后 ( 组不进行再灌注 ) ,分别取结扎前、再灌注前、再灌注 2 4 0 min血测定内皮素 (endochelin ,ET)、一氧化氮 (nitric oxide NO)浓度和组织型纤溶酶原激活剂 (tissue- type plasminogen activa-tor,t- PA )、纤溶酶原激活剂抑制物 (,plasm inogen activator inhibitor PAI)活性。结果　冠状动脉结扎后 ,血浆ET、NO浓度和 PAI活性显著升高 (P<0 .0 1) ,t- PA活性显著下降 (P<0 .0 1) ,再灌注后 ,血浆 ET、NO浓度和 PAI活性进一步升高 ,t- PA活性进一步下降 ,与再灌注前对比均有显著性差异 (P<0 .0 1)。再灌注后 ,与 IR组对比 ,卡托普利、缬沙坦均能显著的升高 t- PA活性 ,降低血 PAI活性和 ET、NO浓度 (P<0 .0 1)。结论　卡托普利、缬沙坦有改善缺血再灌注过程中纤溶活性、抑制内皮细胞释放 ET、NO的有益作用     

兔肾脏二甲基精氨酸二甲基氨基水解酶活性在动脉粥样硬化和虎杖干预中的变化

目的:研究动脉粥样硬化(AS)时二甲基精氨酸二甲基氨基水解酶(DDAH)活性的改变以及虎杖(HZ)对其的干预作用。方法:将36只日本大耳白兔分为正常对照组(NC组)、高脂组(HC组)、高脂加 1、3、9 g/d 3种不同剂量HZ组(SHZ组、MHZ组、LHZ组)和高脂加L 精氨酸组(L Arg组),测定非对称性二甲基精氨酸(ADMA) 水平及肾脏DDAH活性。结果: HC组AS斑块明显,腹主动脉壁中层细胞一氧化氮合酶(NOS)活性增强,内皮细胞染色减弱,ADMA水平增高,而肾脏DDAH活性却明显降低;不同剂量 HZ组呈剂量依赖性改善上述各项指标。结论:AS时DDAH活性降低而致血浆ADMA水平增高和 NOS系统紊乱,HZ能呈剂量依赖性地提高DDAH活性并具有抗AS效应。     

围产期高盐饮食对雄性子代大鼠肠系膜动脉DDAH2/ADMA/eNOS/NO通路的影响

目的探讨围产期高盐饮食对雄性子代大鼠肠系膜动脉二甲基精氨酸二甲胺水解酶2(DDAH2)/非对称性二甲基精氨酸(ADMA)/内皮型一氧化氮合酶(e NOS)/一氧化氮(NO)通路的影响。方法实验大鼠分为2组:正常饮食(NSD)组和高盐饮食(HSD)组,分别在围产期以普通饲料(含1%Na Cl)和高盐饲料(含8%Na Cl)喂养,分娩后雄性子鼠继续相同饲料喂养至16周。测量子鼠血压,检测肠系膜动脉内皮依赖性舒张功能,检测血浆和肠系膜动脉NO含量、e NOS活性、ADMA含量,检测肠系膜动脉DDAH2活性及DDAH1和DDAH2蛋白质表达水平。结果 16周时,HSD组收缩压显著高于NSD组(P0.01)。HSD组大鼠肠系膜血管张力低于NSD组(P0.01);用ADMA孵育血管环后,NSD组血管张力显著减弱,而HSD组未见显著性变化。与NSD组比较,HSD组血浆NO含量降低(P0.05),e NOS活性降低(P0.01),ADMA含量增加(P0.05);HSD组肠系膜动脉NO含量下降(P0.01),e NOS活性下降(P0.01),ADMA含量升高(P0.05)。HSD组DDAH2活性降低(P0.01),DDAH2蛋白质表达显著降低(P0.01);DDAH1蛋白质表达未见显著改变。HSD组肠系膜动脉指标相关性分析:e NOS活性与NO含量呈正相关,ADMA含量与e NOS活性呈负相关,DDAH2活性、DDAH2蛋白质表达与ADMA含量呈负相关。结论母体围产期高盐饮食导致其雄性子代收缩压增高,肠系膜动脉内皮依赖性舒张功能障碍,此与肠系膜动脉DDAH2表达下降、活性降低和DDAH2/ADMA/e NOS/NO通路障碍有关。     

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.     

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.