SHR心肌组织内血管紧张素转换酶活性的变化及西拉普利的作用

目的 探讨心肌组织内血管紧张素转换酶活性在自发性高血压大鼠不同发病阶段的变化及其与左室肥厚及心肌纤维化的关系以及西拉普利的作用。方法 用荧光测定法检测自发性高血压大鼠不同发病阶段心肌组织内血管紧张素转换酶的活性;应用大体及组织病理学检查结合图象分析等方法检测自发性高血压大鼠心肌肥厚和心肌纤维化的动态改变。结果 SHR心肌组织内血管紧张素转换酶活性在第6周和第14周时无明显改变,24周则为明显增高,与代表间质纤维化的参数CVF同步变化;代表血管周围时纤维化的参数PVCA则从第6周开始增高,第14和24周持续增加,代表左室肥厚的参数LV、LVI及CA从14周开始增加,24周更为明显;这些变化均与ACE的变化不同步,而与收缩压变化基本同步;西拉普利可使心肌组织内血管紧张素转换酶活性、代表左室肥厚及心肌纤维化的参数恢复至对照组的水平。结论 SHR心肌组织内血管紧张素转换酶活性在高血压的中晚期增高,与代表间质纤维化的参数CVF呈同步变化,提示心肌间质纤维化的发生可能与ACE的增高有关;西拉普利可有效地降低SHR心肌组织内血管紧张素转换酶活性并预防和逆转左室肥厚及心肌纤维化。     

SHR心肌组织内血管紧张素转换酶活性的变化及西拉普利的作用

目的探讨心肌组织内血管紧张素转换酶活性在自发性高血压大鼠不同发病阶段的变化及其与左室肥厚及心肌纤维化的关系以及西拉普利的作用。方法用荧光测定法检测自发性高血压大鼠不同发病阶段心肌组织内血管紧张素转换酶的活性;应用大体及组织病理学检查结合图象分析等方法检测自发性高血压大鼠心肌肥厚和心肌纤维化的动态改变。结果SHR心肌组织内血管紧张素转换酶活性在第6周和第14周时无明显改变,24周则为明显增高,与代表间质纤维化的参数CVF同步变化;代表血管周围时纤维化的参数PVCA则从第6周开始增高,第14和24周持续增加,代表左室肥厚的参数LV、LVI及CA从14周开始增加,24周更为明显;这些变化均与ACE的变化不同步,而与收缩压变化基本同步;西拉普利可使心肌组织内血管紧张素转换酶活性、代表左室肥厚及心肌纤维化的参数恢复至对照组的水平。结论SHR心肌组织内血管紧张素转换酶活性在高血压的中晚期增高,与代表间质纤维化的参数CVF呈同步变化,提示心肌间质纤维化的发生可能与ACE的增高有关;西拉普利可有效地降低SHR心肌组织内血管紧张素转换酶活性并预防和逆转左室肥厚及心肌纤维化。     

依那普利或氯沙坦对SHR左室肥厚和心肌纤维化的影响

目的:观察自发性高血压大鼠(SHR)左室肥厚和心肌纤维化各指标的改变,以及依那普利和氯沙坦的保护作用.方法:雄性SHR(n=30)自第10周始服用依那普利(20mg@kg-1@d-1),或氯沙坦(25mg@kg-1@d-1),或二者合用(依那普利10mg@kg-1@d-1,氯沙坦12.5mg@kg-1@d-1)至第16周,并以年龄、性别、数量配对的未治疗SHR和Wistar-kyoto(WKY)大鼠作对照.测定收缩压(SBP)、左室重量(LVM)以及左室重量指数(LVMI)和左室心肌胶原含量;计算机图象分析心肌细胞大小、心肌胶原容积分数(CVF)和血管周围胶原面积(PVCA).结果:SHR的SBP、LVM、LVMI、心肌胶原含量、心肌细胞的横截面积、CVF和PVCA均显著高于WKY对照组(P＜0.001).SHR治疗组上述指标显著低于SHR未治疗组(P＜0.01),依那普利与氯沙坦之间无显著差别(P＜0.05).二者合用比单用依那普利或氯沙坦更有效(P＜0.05).结论:依那普利和氯沙坦可显著的降低血压、逆转SHR早期左室肥厚和心肌纤维化,而且二者合用在逆转左室肥厚和心肌纤维化方面效果更明显.     

结缔组织生长因子与高血压大鼠心肌纤维化相关性及伊贝沙坦的干预研究

目的探讨结缔组织生长因子(CTGF)在高血压大鼠心肌纤维化发生发展中的作用,以及伊贝沙坦改善高血压所致心室重构和心肌纤维化可能的作用机制。方法20只12周龄雄性自发性高血压大鼠(SHR)随机分为SHR组和伊贝沙坦(IRB)组各10只,IRB组每只大鼠予以伊贝沙坦50 mg.kg-1.d-1灌胃,给药时间12周,同时取10只12周龄雄性Wistar大鼠作为对照组(WKY组),用免疫组织化学的方法对转化生长因子β1(TGF-β1)、CTGF在3组大鼠的左室心肌的分布及表达进行半定量分析;用逆转录-聚合酶链反应检测TGF-β1、CTGF mRNA在心肌表达水平;用MOSSON染色法观察左室心肌胶原形态,图像分析测量胶原容积分数(CVF)和血管周围胶原面积(PVCA)。结果(1)左室重量指数(LVI)、CVF、PVCA在SHR大鼠组明显高于WKY大鼠组(P<0.01);与SHR组比较,伊贝沙坦组则显著降低(P<0.05)。(2)CTGF主要在血管平滑肌和心肌间质中表达,相关分析表明:CTGF与TGF-β1(r=0.562,P<0.05)、CVF(r=0.715,P<0.01)、PVCA(r=0.786,P<0.01)呈正相关;(3)CTGF及其mRNA在SHR组左室心肌中的表达较WKY组明显增强(P<0.05),与SHR组比较,IRB组则明显减少。结论高血压大鼠心室肌CTGF表达增加,伊贝沙坦能抑制高血压大鼠心室肌CGTF表达,且明显改善了高血压心室重构和心肌纤维化。     

食盐对高血压大鼠及正常血压大鼠心肌纤维化的影响

目的:观察食盐对自发性高血压大鼠(SHR)及正常血压大鼠(WKY)心肌纤维化的影响,并探讨其可能机制。方法:SHR和WKY各20只分别分为两组:①高盐饮食组(SHRSL,n=10和WKYSL,n=10)饮用含2％NaCl溶液;②正常盐饮食组(SHRNS,n=10和WKYNS,n=10)饮用不含NaCl清水,共饲养6周。VG染色和图像处理观察心肌纤维化情况,放免测定心肌局部内皮素-1(ET-1)含量。结果:①SHRSL组心肌间质胶原百分比(CVF)及血管周围胶原面积与血管腔面积百分比(PVCA)显著高于SHRNS(P<0.01),WKYSL组的CVF、PVCA明显高于WKYNs组(P<0.05);②SHRSL组心肌局部ET-1含量显著高于SHRNS组(P<0.01),WKYSL组与WKYNS组心肌局部ET-1含量无差别(P>0.05)。结论:高盐饮食可引起SHR及WKY心肌纤维化,盐负荷后SHR心肌局部ET-1含量的增加可能是SHR心肌纤维化加重的原因之一。     

依那普利或氯沙坦对SHR左室肥厚和心肌纤维化的影响

目的 :观察自发性高血压大鼠 (SHR)左室肥厚和心肌纤维化各指标的改变 ,以及依那普利和氯沙坦的保护作用。方法 :雄性 SHR(n=30 )自第 1 0周始服用依那普利 (2 0 mg.kg- 1 .d - 1 ) ,或氯沙坦 (2 5 mg.kg - 1 .d - 1 ) ,或二者合用 (依那普利1 0 mg.kg - 1 .d - 1 ,氯沙坦 1 2 .5 mg.kg - 1 .d - 1 )至第 1 6周 ,并以年龄、性别、数量配对的未治疗 SHR和 Wistar- kyoto(WKY)大鼠作对照。测定收缩压 (SBP)、左室重量 (L VM)以及左室重量指数 (L VMI)和左室心肌胶原含量 ;计算机图象分析心肌细胞大小、心肌胶原容积分数 (CVF)和血管周围胶原面积(PVCA)。结果 :SHR的 SBP、L VM、L VMI、心肌胶原含量、心肌细胞的横截面积、CVF和 PVCA均显著高于 WKY对照组 (P<0 .0 0 1 )。 SHR治疗组上述指标显著低于 SHR未治疗组 (P<0 .0 1 ) ,依那普利与氯沙坦之间无显著差别 (P<0 .0 5 )。二者合用比单用依那普利或氯沙坦更有效 (P<0 .0 5 )。结论 :依那普利和氯沙坦可显著的降低血压、逆转 SHR早期左室肥厚和心肌纤维化 ,而且二者合用在逆转左室肥厚和心肌纤维化方面效果更明显     

麝香保心丸对自发性高血压大鼠心肌纤维化的干预研究

目的探讨麝香保心丸对自发性高血压大鼠（SHR）心肌纤维化的影响。方法24只8周龄雄性SHR大鼠,随机分为两组：麝香保心丸干预组（SB组）、SHR阳性对照组（SHR组）,每组12只;12只同龄雄性正常血压京都威斯特大鼠（WKY）作为正常对照组（WKY组）。SB组每只大鼠每天给予麝香保心丸112.5mg/kg溶于1.5mL蒸馏水中灌胃,SHR组及WKY组给予等量蒸馏水灌胃,持续16周。处死动物后,称取左室重量（LVM）,计算左室相对重量（LVM/BW）,然后取左室组织标本进行MASSON染色观察胶原纤维增生情况,测定胶原容积分数（CVF）、血管周围胶原面积（PVCA）。透射电镜观察心肌细胞超微结构变化。结果SB组的LVM、LVM/BW明显低于SHR组（P〈0.05）,但仍高于WKY组（P〈0.05）。MASSON染色：SB组与SHR组比较,纤维组织明显减少,心肌细胞间隙较清晰,血管周围胶原聚积明显减少,但比WKY组纤维组织增多。SB组CVF、PVCA较SHR组明显降低（P〈0.05）,但SB组与WKY组比较,CVF增加（P〈0.01）,PVCA也增加（P〈0.05）。电镜下所见：WKY组大鼠心肌纤维结构清晰,且排列整齐,线粒体排列整齐,无肿胀变性,间质中胶原纤维少且排列稀疏。SHR组大鼠线粒体略肿胀,间质中成纤维细胞、胶原纤维明显增生且胶原纤维排列紊乱。SB组与SHR组比较线粒体排列整齐,无肿胀变性,间质中成纤维细胞、胶原纤维明显减少。结论麝香保心丸具有减轻SHR心肌纤维化、改善心脏功能的作用。     

厄贝沙坦对SHR左心室肥厚和心肌纤维化的影响

目的 探讨厄贝沙坦对自发性高血压大鼠(SHR)左心室肥厚(LVH)和心肌纤维化的影响。方法 16只16周龄雄性SHR,随机分为厄贝沙坦治疗组和SHR空白对照组;另设同源的WKY大鼠8只为正常对照组。治疗组予厄贝沙坦15 mg/（kg·d）灌胃给药,8周后处死动物,测量左心室心肌厚度并称质量,计算左心室质量/体质量比(LVM/BM);通过Van Gieson染色法观察左心室心肌胶原变化,对左心室心肌胶原容积分数(CVF)和血管周围胶原面积(PVCA)进行定性和半定量分析;HE染色光镜观察左心室心肌病理变化。结果 与WKY组相比,SHR对照组的尾动脉收缩压(SBP)、LVM/BM、左心室壁厚度、CVF、PVCA、均显著增高(P<0.01);与SHR对照组相比,厄贝沙坦治疗组能有效降低SHR的SBP,改善LVH(P<0.01),减少心肌间质及心肌小动脉周围的胶原(P<0.01)。结论 厄贝沙坦可有效降低SHR血压,减轻心肌纤维化和LVH。     

高血压大鼠心脏肥厚过程中心肌细胞凋亡心肌纤维化动态观察

目的 探讨SHR心脏肥厚进展阶段心肌细胞凋亡、心肌纤维化及左室重构特点及其相互关系。方法 分别采用末端脱氧核糖核苷酸转移酶介导dUTP缺口末端标记（TUNEL）、放射免疫测定及病理检查方法对16周、24周龄、32周龄SHR心肌细胞凋亡指数（APOI）、心肌胶原容积分数（VF）和心肌血管周围胶原面积（PVCA）、血浆和组织血管紧张素Ⅱ检测,并以同龄Wister大鼠作对照。结果 与同龄正常血压Wistar大鼠比较,SHR各周龄组收缩压明显增高、心脏肥厚指标心脏重量（HW）、左室重量（LVW）、左室重量指数（LVW/BW) 显著增加;各周龄组SHR心肌细胞APOI显著增加,各周龄组间无显著性差异;各周龄组SHR大鼠血浆、心肌组织Ang Ⅱ明显增高;24、32周龄SHR的CVF和PVCA显著增加;SHR心肌组织Ang Ⅱ分别与APOI、CVF呈显著正相关,APOI与CVF呈显著正相关。结论 心肌细胞凋亡与心肌纤维化参与SHR代偿性心脏肥厚阶段心脏重构病理过程,组织Ang Ⅱ是导致SHR代偿性心脏肥厚阶段心肌细胞凋亡与心肌纤维化的重要机制之一。     

自发性高血压大鼠心肌重建反应和卡托普利的保护效应

本研究旨在观察自发性高血压大鼠(SHR)心肌重建反应以及卡托普利的保护作用.通过称重法计算左室重量指数(LVI);使用测微技术,在HE染色切片上测量心肌细胞横径(TDM);运用计算机图像分析技术,在苦味酸天狼猩红染色切片上检测心肌胶原体积比例(CVF)和心肌血管周围胶原面积与管腔面积比例(PVCA).结果显示:15周龄SHR的LVI、TDM、CVA和PVCA均显著高于相应年龄的Wistar-Kyoto大鼠(WKY),但是,卡托普利(100mg/kg/天)治疗12周后,上述参数恢复正常.提示压力负荷下SHR出现了心肌肥大和心肌纤维化,使心肌结构发生了重建;CAP可以逆转心肌肥大和心肌纤维化,因而改善心肌重建.     

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.