亚甲基四氢叶酸还原酶基因多态性与糖尿病肾病相关性研究

目的：研究亚甲基四氢叶酸还原酶（MTHFR）基因多态性与2型糖尿病肾病的关系。方法：运用聚合酶链反应－限制性片段长度多态性技术（PCR－RFLP）检测85例2型糖尿病患者（其中39例伴糖尿病肾病）及57例正常对照组MTHFR C677T基因型,采用高效液相色谱法测定血浆同型半胱酸水平。结果：糖尿病肾病组MTHFR基因TT纯合基因型,CT杂合基因型及T等位基因频率（分别为38．21％,51．28％,53．85％）均明显高于糖尿病不伴肾病组（分别为19．57％,28．26％,33．70％）及正常对照组（分别为17．54％,28．07％,31．58）,基因型和等位基因频率分布差异均有统计学意义（P＜0．05）,而MTHFR基因该多态性在不伴肾病组与正常对照组之间差异无显著性（P＞0．05）,T等位基因与糖尿病肾病的发生密切相关（OR＝2．30,95％可信区间;1．24－4．26）。糖尿病肾病组,糖尿病不伴肾病组及正常对照组中,MTHFR基因有C677T突变者血浆同型半胱氨酸水平均显著高于无基因突变者。结论：MTHFR基因C677T位碱基突变致血浆同型半胱氨酸水平高是糖尿病肾病发病的重要遗传因素。     

MTHFR基因多态性与冠心病的关系

目的研究天津地区人群N^5,N^10-亚甲基四氢叶酸还原酶（MTHFR）基因C677T多态性与冠心病的关系。方法应用聚合酶链反应（PCR）技术和限制性酶切片段长度多态性（RFLP）分析技术检测50例冠心病患者（冠心病组）和50例正常人（对照组）的MTHFR基因C677T多态性,应用高效液相色谱法测定血浆同型半胱氨酸（Hcy）水平,采用125I标记放免法测定血清叶酸浓度。结果1.冠心病组与对照组MTHFR基因频率分布不同（P〈0.05）,对照组CC型、TC型、TT型基因频率分别为52.0%,28.0%,20.0%,冠心病组分别为26.0%,44.0%,30.0%。冠心病组T等位基因频率为52.0%,C等位基因频率为48.0%,与对照组比较有显著性差异（P〈0.05）。2.两组的TT基因型者血浆Hcy浓度均明显高于CC和TC基因型者（P〈0.05）,而后两者间无显著性差异（P〉0.05）。3.冠心病组Hcy浓度高于照组（P〈0.05）,两组叶酸水平无显著性差异（P〉0.05）,血浆Hcy浓度与叶酸水平呈显著负相关（r分别为-0.617和-0.588,P〈0.05）。结论MTHFR基因C677T点突变与冠心病发病密切相关,MTHFR基因纯合突变是引起高Hcy血症的一个重要的遗传因素。     

2型糖尿病颈动脉内中膜厚度与亚甲基四氢叶酸还原酶基因C677T多态性及血浆同型半胱氨酸水平的关系

目的探讨亚甲基四氢叶酸还原酶（MTHFR）基因C677T多态性及同型半胱氨酸水平与早期2型糖尿病（T2DM）颈动脉内中膜厚度（IMT）的关系及影响因素。方法测定T2DM患者及对照组（NC）颈动脉IMT,分为糖尿病无内中膜增厚组（DM1）和糖尿病合并内中膜增厚组（DM2）。用PCR—RFLP检测MTHFR基因C677T多态性。结果DM。组MTHFR C677T基因TT基因型频率与NC组比较明显增高（40．4％ vs 17．3％,P〈0．01）,与DM1组比较明显增高（40．4% vs 17．9％,P〈0．01）,DM1组与NC组比较无统计学差异（17．9％ vs 17．3％,P〉0．05）。T等位基因频率DMz组与NC组比较明显增高（57．0％ vs 33．7％,P〈0．01）,与DM1组比较明显增高（57．0％ vs 42．9％,P〈0．01）,差异有统计学意义。结论高同型半胱氨酸血症、T等位基因是早期糖尿病患者颈动脉内中膜增厚的危险因素之一,血浆同型半胱氨酸水平与MTHFR C677T基因多态性有关。     

同型半胱氨酸代谢异常与冠心病的关系

目的：探讨同型半胱氨酸代谢异常与冠心病的关系。方法：选择245例健康对照者和入住我院冠心病房的439例经冠状动脉造影证实为冠心病者作为研究对象，监测其血浆同型半胱氨酸（Hcy）、叶酸和VitB12水平，分析亚甲基四氢叶酸还原酶（MTHFR）基因多态性，并根据冠状动脉造影结果，分成单支、双支和三支病变组，分析病变支数与MTHFR基因多态性的关系。结果：冠心病患者血浆Hcy水平（17．61＋11．62）显著高于对照组（12．92＋8．23）（P〈0．001），叶酸和VitBl2水平低于对照组（P〈0．05）。冠心病组TT基因型明显高于对照组（P〈0．05），冠心病组中三支血管病变组的TT基因频率比单支和双支血管病变组高（P〈0．005），TT型纯合子的血浆Hcy含量与CC型纯合子和CT杂合子比较具统计学差异（P〈0．001），而叶酸和VitB12含量低于后两者（P〈0．05）。结论：血浆Hcy含量和MTHFR基因突变相关，其TT纯合子血浆Hcy水平最高，而在三支血管病变组的TT基因频率最高，提示MTHFR基因突变可导致Hcy水平升高，是冠心病的危险因素。     

N5,N10-亚甲四氢叶酸还原酶基因多态性及血浆同型半胱氨酸水平与心肌梗死的关系

研究N^5,N^10-亚甲四氢叶酸还原酶基因多态性及血浆同型半胱氨酸水平与心肌梗死的关系。运用多聚酶链反应-限制片长多态性技术检测178例心肌梗死患者及178例正常人N^5,N^10-亚甲四氢叶酸还原酶基因多态性，用高效液相色谱仪和荧光检测仪测定血浆总同型半胱氨酸水平。结果发现，N^5,N^10-亚甲四氢叶酸还原酶有3种基因型，即纯合子突变型（TT），杂合子突变型（TC）及正常型（CC），心肌梗死组TT型频率为35.4%，TC型频率为53.8%。CC型频率为10.8%。T等位基因频率为62.3%。C等位基因频率为37.7%，正常组中TT型频率为20.1%。TC型频率为55.8%。CC型频率为24.1%。T等位基因频率为32.1%,C等位基因频率为67.9%，且心梗死组TT高于正常组。正常人群中TT基因型者血浆总同型半胱氨酸水平明显高明于（TC CC）基因型者，心肌梗死患者血浆总同型半胱氨酸水平显著高于正常组，多因素分析显示，N^5,N^10-亚甲四氢叶酸还原酶基因突变型TT可能是心肌梗死发病一个危险因素，结论提示，N^5,N^10-亚甲四氢叶酸还原酶TT基因型突变可能升高个体血浆总同型半胱氨酸水平，N^5,N^10-亚甲四氢叶酸还原酶基因可能是心肌梗死的易感基因之一，N^5,N^10-亚甲四氢叶酸还原酶基因突变型TT及高同型半胱氨酸血症可能是心肌梗死发病的一个危险因素。     

不同类型脑梗死Hcy水平及MTHFR基因多态性

目的探讨血浆同型半胱氨酸（Hcy）水平、亚甲基四氢叶酸还原酶（MTHFR）基因多态性与不同类型脑梗死的关系。方法采用荧光偏振免疫法及PCR-限制性内切酶片段长度多态性技术分别检测脑血栓形成、腔隙性脑梗死患者及健康对照者的血浆Hcy水平及MTHFR C677T基因多态性。结果脑血栓形成患者的TT基因型及T等位基因频率均显著高于对照组（P〈0.05）,脑血栓形成及腔隙性脑梗死患者血浆Hcy水平均显著高于对照组（P〈0.05）。结论血浆Hcy水平升高是脑血栓形成及腔隙性脑梗死的危险因素。MTHFR基因677TT型可引起血浆Hcy水平升高,是脑血栓形成的危险因素。     

亚甲基四氢叶酸还原酶基因C677T突变与高尿酸血症的相关性研究

目的探讨高尿酸血症（HUM）与亚甲基四氢叶酸还原酶（MTHFR）基因C677T突变及高血糖、肥胖和高血压等的相关性。方法从青岛地区糖尿病流行病学调查数据库中，随机选取HUM＋T2DM患者79例、HUM无T2DM患者（HUM组）90例、并选取T2DM无HUA患者（DM组）90例和健康对照（NC）91例。采用聚合酶链反应-限制性片段长度多态性技术检测MTHFR基因突变。结果HUM组和HUM＋T2DM组MTHFR677T等位基因频率分别为46．7％和51．3％，TT基因型频率分别为23．3％和26．6％，两组差异无统计学意义（P〉0．05）；T等位基因和TT基因型频率在NC组和DM组间差异无统计学意义（P〉0．05）；而HUM组和HUM＋T2DM组MTHFR677T等位基因型频率和TT基因型频率均分别高于NC组和DM组（P〈0．005）。CT和TT基因型患者平均血尿酸水平（分别为394．2μmol／L和465．8μmol／L）明显高于CC基因型者（347．3μmol／L）（P〈0．05）。多因素logistic回归分析表明，调整BMI、SBP、TG、TC及饮酒等因素后显示，MTHFR基因型是HUM患病的独立危险因素。结论MTHFR基因C677T突变是青岛地区人群发生HUM的独立危险因素。     

类风湿关节炎合并心血管病变患者血清同型半胱氨酸水平及其与亚甲基四氢叶酸还原酶基因多态性的关系

目的检测类风湿关节炎（RA）患者血清同型半胱氨酸水平和亚甲基四氢叶酸还原酶（MTHFR）基因单核苷酸多态性,分析其在RA合并心血管病变患者中的作用。方法收集183例RA患者,分为合并心血管病变组和无心血管病变组,同时选取50名我院健康体检者作为对照组。采用实时荧光定量聚合酶链反应方法测定RA患者和对照组的MTHFR基因rs1801133C／T（677）和rs1801131A／C（1298）2个位点的基因单核苷酸多态性;ELISA法检测3组受试者血清同型半胱氨酸水平。结果①183例RA患者心血管病变发生率约为29．0％,其中合并心血管病变组同型半胱氨酸水平明显高于无心血管病变组（P〈0．001）。②677TT基因型组血清同型半胱氨酸水平高于CC及CT组（P〈0．05）。③RA患者血清同型半胱氨酸水平与心血管事件呈正相关。结论RA合并心血管病变患者血清同型半胱氨酸水平明显高于RA无心血病变组及正常对照组,其水平增高可能与MTHFR677C／T基因多态性有关。血清同型半胱氨酸水平升高可作为RA患者发生心血管事件的预测指标。     

MTHFR基因多态性及Hcy与房颤伴卒中的关系

目的探讨MTHFR基因突变引起Hcy水平升高与中国人种房颤对缺血性卒中的发生是否存在相互关系。方法纳入非瓣膜性房颤和房颤伴缺血性卒中的患者及正常对照组，采用PCR——RFLP的方法研究MTHFR基因677位点上C／T碱基的突变情况。两组计量资料用t检验，多组计量资料用方差分析进行整体比较。结果（1）房颤、房颤伴卒中患者MTHFR基因多态性与血浆Hcy有关，1Tr型Hcy水平（21．38±18．75μmoVL）明显高于CT（14．46±4．70μmol／L），CC（14．33±5．09μmol/L）型；（2）房颤伴卒中组血浆Hcy水平（18．15±13．74μmol/L）较房颤组（13．76±5．12μmol/L）升高明显。结论（1）房颤伴卒中患者血浆Hcy水平明显升高，高Hcy水平可能是非瓣膜性房颤发生卒中的危险因素；（2）MTHFR基因C677T位点突变纯合基因型TT型较CT基因型、CC基因型血浆Hcy升高明显，示TT基因型MTHFR酶活性最低；（3）MTHFR基因C677T位点多态性与房颤伴卒中无关。     

叶酸代谢基因及血浆同型半胱氨酸在老年脑卒中患者中的表达及相关性

目的 探讨四氢叶酸还原酶(MTHFR)C677T位点、甲硫氨酸合成酶还原酶(MTRR A66G位点及血浆同型半胱氨酸(Hcy)在老年脑卒中患者中的表达及相关性。方法 选取2018年1月到2019年6月西宁市第二人民医院收治的80例老年脑卒中患者作为脑卒中组,另选择我院同期体检的73例健康人员作为对照组。采用PCR-RELP法检测患者MTHFR C677T位点和MTRR A66G位点基因多态性,采用全自动生化仪检测血浆Hcy水平,分析不同MTHER、MTRR基因型、血浆Hcy水平与脑卒中关系。结果 脑卒中组TT型、GG型基因频率均高于对照组,CC型、AA型基因频率低于对照组(t=12.771、4.408、4.912、3.921,P 0.05)。脑卒中组各基因型Hcy水平均高于对照组,差异具有统计学意义(t=6.477、10.663、4.227、2.685、2.949、3.929,P 0.05),两组MTHFR C677T的TT型患者Hcy水平均高于CT型、CC型,差异具有统计学意义(P 0.05);两组MTRR A66G位点GG型患者Hcy水平均高于AG型、AA型,差异具有统计学意义(P 0.05)。Spearman相关性分析显示,MTHFR C677T位点、MTRR A66G位点各基因型频率均与Hcy水平呈正相关(r=0.779、0.684、0.716、0.806、0.758、0.818,P 0.05);Logistic回归分析显示,MTHFR C677T位点TT型、Hcy水平是影响脑卒中发生的危险因素[OR (95%CI)=3.167(1.421～5.385)、2.822(1.652～4.770),P 0.05]。结论 老年脑卒中患者MTHFR C677T位点TT型、MTRR的A66G位点GG型基因频率、血浆Hcy水平高于健康人群,其中MTHFR C677T位点TT型基因频率、血浆Hcy水平是影响脑卒中发生的重要因素。     

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.