研究氢气的效应如何避免内源性氢气的干扰

　　美国harvard大学关于氢气治疗肝炎的研究中，曾经给我们提供了如何将内源性氢气压制的方法，是使用几种抗生素联合的方法，当然没有问题。这里的报道给我们新的设计方案。很可能这个药物就是比较特异的能减少大肠产生氢气的方法。

　　这个药物是非常好的内源性氢气产生抑制方法，这个药物对氢气造成致命性打击，也许能导致一些负作用就是内源性氢气的作用。

　　另一个相关想法，大肠产生氢气太多是IBS的原因吗，看来依靠大肠产生氢气治疗疾病也不一定是一个很好的办法。当然可以从另一个角度看，IBS既然大肠产生氢气太多，这种人可能每天享受氢气的好处而不知道。可以考虑调查这种患者其他疾病的发病率如何。对理解氢气的效应有帮助。另外美国的研究既然发现氢气能治疗肠炎，IBS的原因可能是大肠产生氢气太多，而氢气能治疗肠炎，自相矛盾吗?

　　也许原因是这样的，氢气产生后很快会被另一种细菌转化成甲烷。氢气一般的危害比较小，因为容易扩散。但甲烷的危害可能比较大。

　　另外，使用这种抗生素治疗该疾病，也许有更复杂的原因。这种患者的炎症也许与这类细菌有关。

　　另外，不知道更长期的效果如何，需要继续跟踪研究。

　　Rifaximin(利福昔明)本品系利福霉素衍生物，是第一个非氨基糖甙类肠道抗生素。本品作用强，抗菌谱广。本品对革兰氏阳性需氧菌中的金黄色酿脓葡萄球菌、表皮葡萄球菌及粪链球菌; 对革兰氏阴性不规则氧菌中的沙门氏菌属、大肠杆菌、志贺氏菌属、小肠结肠炎耶尔森氏菌、球菌;革兰氏阴性厌氧菌中的拟杆菌属有高度活性。

　　以上引自网上资料

　　两项由Cedars-Sinai的研究者进行的Ⅲ期临床试验结果表明，一种靶向抗生素能够有效持久地缓解肠激惹综合征(IBS)。Rifaximin是第一个不仅在服药期间，而且停止用药后能持续缓解IBS症状的药物。

　　研究者发现服用Rifaximin的患者不仅服药期间IBS症状减轻，包括特殊症状例如：胀气、腹痛和粪便硬度改变，并且当他们停药后10周内，症状持续缓解。

　　该研究的结果于5月3日在新奥尔良的消化疾病周会议上被公布。Cedars-Sinai公司的胃肠动力项目总监，临床试验主要研究者Mark Pimentel博士说：“这些研究证实了变异的消化道细菌在IBS扮演的角色。这些发现表明靶向抗生素安全持久改善IBS。”

　　IBS是美国最常见的胃肠道紊乱疾病，超过20%的美国人受疾病影响。IBS患者通常被描述为“便秘为主要症状”“腹泻为主要症状”或“腹泻便秘交替”。除这些症状外，IBS患者常常腹痛或痉挛，气体过多或胀气，比正常大便硬或松散，以及肉眼可见的腹部膨胀。

　　因为IBS病因不明，以往的治疗主要集中在减轻症状，减缓或加速消化过程。Pimentel和同事早期的研究，给受试者进行乳果糖氢呼吸实验，揭示了IBS最常见症状——胀气，和细菌发酵之间可能存在关联。实验监测了呼吸中氢和甲烷(发酵细菌产生的气体)的浓度。实验显示这些气体浓度升高，表明小肠细菌过度生长，或SIBO，可能导致IBS。

　　超过1200名患者参加了rifaximin双盲、多中心、Ⅲ期临床研究，这是一种胃肠道内不可吸收的抗生素，FDA已批准治疗旅行腹泻和肝性脑病。轻到中度腹泻和胀气的IBS患者被随机挑选，服用550mg rifaximin或安慰剂两周。然后对病人进行跟踪调查十周。Ⅲ期临床是最后阐明新药安全有效的大规模随机实验。

　　这一发现支持了Pimentel以前的研究，显示IBS由消化道细菌过度生长引起。 “即使你停用这种抗生素，病人会一直感觉良好，这说明我们打击了病因。”Pimentel说。

　　除了Cedars-Sinai公司，其它参与该临床试验的中心包括波士顿Beth Israel Deaconess医学中心，安阿伯的密歇根大学医学中心，查珀尔希尔的北卡罗来纳大学，布里斯托尔的Connecticut Gastroenterology Institute.

　　Rifaximin(利福昔明)由Salix制药有限公司生产。Salix也提供研究基金。Pimentel发现rifaximin对IBS的作用，Cedars-Sinai拥有该发现的专利权，并已授权给Salix。Pimentel博士是Salix公司的顾问，是它的科学顾问会成员。 (部分引自DXY)

　　http://www.sciencedaily.com/releases/2010/05/100504095220.htm

　　A targeted antibiotic provides effective and long-lasting relief of Irritable Bowel Syndrome symptoms, according to the results of two multisite Phase III clinical trials designed by Cedars-Sinai researchers. Rifaximin is the first drug treatment for IBS that relieves symptoms while it's being administered and continues to benefit patients after they stop taking the drug.

　　Researchers found that patients who took rifaximin not only experienced relief of their IBS symptoms, including specific symptoms of bloating, abdominal pain and stool consistency, while they were taking the antibiotic, but also that their relief was sustained over the 10 week follow-up period when no antibiotic was administered.The results of the studies were presented at the Digestive Disease Week conference in New Orleans on May 3.

　　"These studies validate the role of altered gut bacteria in IBS," said Mark Pimentel, M.D., GI Motility Program director at Cedars-Sinai and the principal investigator of the clinical trail at Cedars. "These findings show that targeted antibiotics provide safe and long-lasting improvement for IBS patients."

　　IBS is the most common gastrointestinal disorder in the United States, affecting more than 20 percent of the population. Traditionally, patients with IBS have been described as having "constipation predominant," "diarrhea-predominant" or an alternating pattern of diarrhea and constipation. In addition to these symptoms, IBS patients often experience abdominal pain or cramps, excess gas or bloating, harder or looser stools than normal and visible abdominal distension.

　　Because the cause of IBS has been elusive, treatments for the disease have historically focused on relieving its symptoms through medications that either slow or speed up the digestive process. Earlier research conducted by Pimentel and colleagues documents a possible link between bloating, the most common IBS symptom, and bacterial fermentation by giving participants lactulose breath tests. The test monitors the level of hydrogen and methane -- the gases emitted by fermented bacteria -- on the breath. Those tests show elevated levels of those gases, indicating that small intestine bacterial overgrowth, or SIBO, may be a cause of IBS.More than 1,200 patients participated in the Phase III, double-blind, multi-center studies of rifaximin, a nonabsorbable antibiotic that stays in the gut and is currently FDA-approved to treat traveler's diarrhea and hepatic encephalopathy. IBS patients with mild to moderate diarrhea and bloating were randomized to receive 550 milligrams of rifaximin or placebo for two weeks. Patients were then followed for an additional 10 weeks. Phase III trials are randomized studies on large patient groups to definitively demonstrate the safety and effectiveness of a new drug.

　　The findings support previous research by Pimentel indicating that IBS is caused by an overgrowth of bacteria in the gut.

　　"Even after you stop the antibiotic, the patients continue to feel better, which indicates that we did something to strike at what causes the condition," Pimentel said.In addition to Cedars-Sinai, other centers participating in the clinical trials included Beth Israel Deaconess Medical Center in Boston, University of Michigan Medical Center in Ann Arbor, University of North Carolina at Chapel Hill, Connecticut Gastroenterology Institute in Bristol, Conn.

　　Rifaximin is marketed by Salix Pharmaceuticals, Inc. Salix also provided funding for the studies. Pimentel discovered the use of rifaximin for IBS, and Cedars-Sinai holds patent rights to this discovery and has licensed rights to the invention to Salix. Dr. Pimentel is a consultant to Salix, Inc, and serves on its scientific advisory board.