低碳水化合物饮食对2型糖尿病患者糖代谢的改善作用

探讨低碳水化合物饮食对2型糖尿病（T2DM）患者肠道微生物和空腹高血糖的影响。

选择2019年5月至2019年8月我院内分泌科招募的100例T2DM患者为研究对象,患者随机分配到干预饮食组（LCD组,低碳水化合物饮食）或控制饮食组（LFD组）。LFD组患者的饮食为500 g蔬菜/d,100 g主食/餐（300 g/d）,3汤匙油/d,两餐之间提供稳定血糖、低血糖指数水果,5种蛋白质（220 mL牛奶、1个鸡蛋、100 g鱼虾、50 g大豆、50 g肉）/d,6 g盐/ d。LCD组每天摄入杏仁56 g以取代150 g/d富含碳水化合物的主食,其余饮食方案与LFD组相同。收集所有参与者的粪便标本,取豌豆大小的粪便置入1.5 mL的试管中,立即于−80 ℃保存。使用QIAAMP^® DNA粪便抽提试剂盒进行粪便样本的总DNA提取,随后进行16S rRNA基因测序,对其菌群进行分析。

LCD组患者肠道微生物群Shannon指数,Chao指数和Simpson指数显著高于LFD组（均P＜0.05）。两组患者按照规定饮食3个月后肠道微生物组检测显示,总共有9个门,其中排名前5位的细菌门约占所有细菌的96.00%。LCD组患者以拟杆菌门为主（72.32%）,其次为假单胞菌门（13.81%）、变形菌门（8.22%）、梭杆菌门（0.03%）、放线菌门（0.63%）。LFD组患者肠道菌群门水平的细菌组成与LCD组相近。其中,LFD组梭杆菌门丰度（0.35%）高于LCD组（0.03%）。同时,LCD组产单链脂肪酸细菌（Roseburis）和瘤胃球菌的相对丰度升高。两组之间3种主要营养素的总能量和热量比例差异无统计学意义（均P＞0.05）。干预3个月时,两组患者的总能量差异无统计学意义（P＞0.05）。与LFD组相比,LCD组患者来自碳水化合物的热量减少,而来自脂肪的热量显著增加（均P＜0.05）。此外,干预后,LCD组患者中有40%来自碳水化合物的热量达到LCD标准,而LFD组患者中有25%来自脂肪的热量达到LFD标准。治疗3个月时,LCD组患者HbA1c下降幅度大于LFD组（P＜0.05）。干预期间,LCD组有3例、LFD组有5例患者降糖药物使用量减少,其余受试者无显著变化。

低碳水化合物饮食可能通过改善T2DM患者肠道菌群区系进一步改善患者的糖代谢。

     

Fusobacterium prausnitzii and related species represent a dominant group within the human fecal flora

The human gut microflora plays a key role in nutrition and health. It has been extensively studied by conventional culture techniques. However these methods are difficult, time consuming and their results not always consistent. Furthermore microscopic counts indicate that only 20 to 40% of the total flora can be cultivated. Among the predominant species of the human gut, Fusobacterium prausnitzii was reported either as one of the most frequent and numerous species or was seldom retrieved. We designed and validated a specific rRNA-targeted oligonucleotide probe, called S-*-Fprau-0645-a-A-23, to accurately detect and quantify F. prausnitzii and relatives within the human fecal microflora. The target group accounted for 5.3 +/- 3% of total bacterial 16S rRNA using dot blot hybridization (10 human fecal samples) and 16.5 +/- 7% of cells stained with Dapi using in situ hybridization (10 other human fecal samples). A specific morphology seemed to be typical and dominant: two cells forming an asymmetrical double droplet. This work showed that F. prausnitzii and phylogenetically related species represent a dominant group within the human fecal flora.     

Effect of environmental factors and influence of rumen and hindgut biogeography on bacterial communities in steers

Feces from cattle production are considered important sources of bacterial contamination of food and the environment. Little is known about the combined effects of arctic temperatures and fodder tannins on rumen and hindgut bacterial populations. Individual rumen liquor and rectal fecal samples from donor steers fed either alfalfa silage or sainfoin (Onobrychis viciifolia Scop.) silage and water ad libitum were collected weekly on the first three sampling days and fortnightly afterwards. The daily ambient temperatures were registered and averaged to weekly mean temperatures. Steers fed sainfoin silage had lower (P < 0.05) concentrations of branched-chain volatile fatty acids (VFA) than those fed alfalfa silage. All VFA concentrations were higher (P < 0.001) in rumen liquor samples than in fecal samples. The interaction of sample type and diet showed a significant effect (P < 0.05) on the proportions of the bacterial community that were from the phyla Proteobacteria and Verrucomicrobia. Ambient temperature had an indirect effect (P < 0.05) on the phylum Firmicutes, as it affected its proportional balance. The bacterial population diversity in samples appeared to decrease concurrently with the ambient temperature. The phylum Firmicutes explained the first principal component at 64.83 and 42.58% of the total variance in rumen liquor and fecal samples, respectively. The sample type had a larger effect on bacterial communities than diet and temperature. Certain bacterial populations seemed to be better adapted than others to environmentally adverse conditions, such as less access time to nutrients due to higher motility and rate of passage of digesta caused by extreme temperatures, or antimicrobials such as tannins, possibly due to an influence of their biogeographical location within the gut.     

Study of murine faecal microflora by cellular fatty acid analysis; effect of age and mouse strain

Analysis of bacteria-derived cellular fatty acids was applied to study differences in faecal floras of inbred mice. The bacterial composition of the faecal flora clearly changes with age, whereas the sex does not affect it. Most interestingly, different mouse strains were found to have different faecal floras. This was particularly observed at the age of 17–19 weeks for stool samples of four different mouse strains; the mice were handled identically in identical environments, and the two congenic strains used were different from each other only by the major histocompatibility complex (MHC). These results suggest that composition of the faecal flora is genetically regulated.     

Simultaneous quantitation of fatty acids,sterols and bile acids in human stool by capillary gas-liquid chromatography

A simple method for the simultaneous gas-liquid chromatographic quantitation of fatty acids, sterols and bile acids from human fecal samples is described. The various compounds are directly converted into the n-butyl ester-trimethylsilyl ether derivatives, without prior isolation from the stool. Under these conditions, fecal bile acid derivatives are well resolved from each other and from those of fecal fatty acids and sterols without overlaps. The method was found to be reproducible and recoveries were similar to those obtained after exhaustive solvent extraction of fecal sterols, fatty acids and bile acids. Optimum derivatization conditions that allowed maximum recovery of fecal components with minimal destruction and application of the method for simultaneous bile acid, fatty acid and sterol analysis in human stool are described.     

ERIC-PCR指纹图谱技术分析糖尿病小鼠肠道细菌群落变化

目的通过比较1型糖尿病模型组和空白对照组雄性小鼠肠道菌群结构的变化,探索糖尿病造模与肠道菌群的关系。方法收集造模2周后空白对照组(n=5)、STZ造模成功组(n=5)和造模不成功组(n=3)ICR小鼠的新鲜粪便样品,提取粪便样品的总DNA,ERIC-PCR扩增形成DNA指纹图谱,借助多变量统计分析方法研究各组样品肠道菌群结构上的异同。结果ERIC-PCR指纹图谱结合偏最小二乘法(PLS-DA)分析表明造模成功组和造模不成功组小鼠的肠道菌群结构显著区别于空白对照组,而造模不成功组小鼠的肠道菌群结构与造模成功组仍有一定的区别。结论STZ诱导的1型糖尿病会造成小鼠的肠道菌群结构的变化,而部分小鼠造模失败可能与这些小鼠的肠道菌群结构有关。     

The intestinal microflora of childhood patients with indicated celiac disease

The fecal short-chain fatty acids concentration was higher (154 +/- 46.9 mmol/L) in childhood patients than in healthy children (96.6 +/- 19.2 mmol/L). On the other hand, pH values were nonsignificantly lower in patients stool (6.78 +/- 0.75 vs. children 7.42 +/- 0.74). Using denaturing gradient gel electrophoresis specific for total bacteria, lactobacilli and bifidobacteria the microbial population was characterized in fecal samples and in duodenal biopsies. Bacteria adhering to duodenal biopsies were not dominating in stool samples. More than 50 % of detected bacterial species belonged to as yet uncultured strains.     

四氯化碳一过性处理对巴马香猪肠道菌群的影响

目的探讨四氯化碳（CCl4）一过性处理对巴马香猪肠道菌群的影响,评估CCl4诱导处理的肝损伤动物模型能否用于肠道微生态研究。方法选取3头雄性巴马香猪,一次性按每千克体重腹腔注射0.25 ml[0.25ml/（kg·bw）]40%CCl4橄榄油溶液。于注射12 h之后的第1、2、3、4、7和10天连续采集粪便,以注射CCl4溶液之前所采集粪便样作对照。分别提取粪样总DNA,采用变性梯度凝胶电泳技术（DGGE）对CCl4一过性处理后巴马香猪肠道菌群的多样性变化进行动态监测。结果PCR-DGGE法分析表明,巴马香猪肠道菌群组成在注射CCl4前后差异无显著性（P〉0.05）。相似性聚类分析结果表明,菌群组成在注射CCl4前后相似度在65%以上。结论CCl4一过性处理后巴马香猪肠道菌群组成未发生显著变化。表明CCl4处理诱导的肝损伤动物模型可以用来研究相关疾病与肠道菌群之间的关系。     

实时荧光定量PCR法研究溃疡性结肠炎患者肠道双歧杆菌属、柔嫩梭菌属及拟杆菌属量的变化

目的应用荧光定量PCR技术对人粪便内双歧杆菌属、柔嫩梭菌属及拟杆菌属进行定量检测,揭示肠道相关菌群改变在溃疡性结肠炎（ulcerative colitis,UC）发病中的作用及意义。方法分别设计双歧杆菌属、柔嫩梭菌属及拟杆菌属的特异性引物。收集溃UC患者粪便标本60份及正常对照标本60份,提取细菌基因组DNA,应用实时荧光定量PCR反应测定细菌的数量。结果UC患者组双歧杆菌属及柔嫩梭菌属的数量较正常对照组明显减少（P〈0．05）,而拟杆菌属的数量较正常对照组明显增多（P〈0．05）,差异有统计学意义。结论UC患者粪便中双歧杆菌属及柔嫩梭菌属的数量较正常对照明显减少,而拟杆菌属的数量较正常对照明显增多,提示肠道菌群与UC的发生、发展有一定的关系。     

Effects of dietary antibiotics on intestinal microflora in broiler chickens

Changes were examined in the intestinal microflora in broiler chickens fed a diet containing antibiotics to obtain fundamental information on the mechanisms of beneficial effect of the antibiotics upon livestock production. Three antibiotics (colistin, bacitracin, and enramycin) were employed as feed additives. Experiments were conducted with broiler chickens in two ways. In one way dietary antibiotics were fed continually at levels approved for use as feed additives for a long term. In the other they were fed the same antibiotics for a short term. Significant changes in microflora were observed mainly in such bacterial groups as aerobic bacteria and Lactobacillus. In the long term administration, three possible modes of variance in the bacterial flora were postulated: Changes directly related to the antibacterial spectrum of antibiotics. Antagonistic changes related to an ecological balance in the bacterial flora. Changes in quantitative balance of bacteria constituting each bacterial group. The change in the intestinal microflora during administration of the antibiotic diet was expressed as a complex form of these transition modes. In the short term administration, it was demonstrated that the effect of the antibiotic diet lingered even 7 days after administration. This suggests that antibiotics used as feed additives may possibly affect the stability of the intestinal microflora.     

Impact of Bifidobacterium longum on human fecal microflora.

The effects of Bifidobacterium longum feedings for five weeks on the fecal microflora, water contents, pH values, ammonia concentration, and beta-glucuronidase activity were investigated in five healthy human volunteers. Although numbers of major bacterial groups of the fecal microflora were not changed by the bifidobacteria feedings, a remarkably decreasing number of lecithinase-negative clostridia was observed. The percentage of lecithinase-negative clostridia and bacteroides to the total bacterial numbers isolated were decreased during the feedings and numbers of C. paraputrificum and C. innocuum were reduced. A significant reduction of fecal pH values for the last week of the feeding was observed. Ammonia concentration and beta-glucuronidase activity in the feces during the feedings were significantly lower than those before or after the feedings. The oral supplement of B. longum may be introduced to improve the fecal properties such as fecal ammonia concentration and beta-glucuronidase activity, but not the composition of fecal flora.     

焦米对番泻叶所致腹泻小鼠的止泻及肠道菌群影响研究

目的考察焦米水对肠道菌群失调性腹泻的调节作用。方法将小鼠分为5组,分别为模型组、正常组和生米组、焦米组、自由恢复组三组实验组,除正常组外,用番泻叶水煎液给小鼠灌胃连续6 d造成小鼠腹泻模型,实验组分别给予生米、焦米及生理盐水作为自由恢复组,每天观察各组小鼠腹泻情况,并且于第2天、第6天取小鼠粪便进行肠道菌群检测,并做菌群计数,数据进行统计学处理。结果成功建立了小鼠肠道菌群失调腹泻模型,焦米组小鼠腹泻较生米组和自由恢复组恢复较快,差异有统计学意义（P〈0.05）。给予生米、焦米的小鼠肠道菌群恢复较快,与自由恢复组相比差异有统计学意义（P〈0.05）,焦米组与生米组相比菌群有一定的提高,但差异无统计学意义（P〉0.05）。结论焦米水能明显的改善小鼠的腹泻症状,焦米有一定的提高小鼠肠道菌群,改善小鼠肠道菌群环境的作用。焦米与生米相比对腹泻小鼠的恢复促进调节作用更好,可能跟米炒焦后所生成的新物质有关。     

Vegan diet in physiological health promotion

We have performed a number of studies including dietary interventions and cross-sectional studies on subjects consuming uncooked vegan food called living food (LF) and clarified the changes in several parameters related to health risk factors. LF consists of germinated seeds, cereals, sprouts, vegetables, fruits, berries and nuts. Some items are fermented and contain a lot of lactobacilli. The diet is rich in fiber. It has very little sodium, and it contains no cholesterol. Food items like berries and wheat grass juice are rich in antioxidants such as carotenoids and flavonoids. The subjects eating living food show increased levels of carotenoids and vitamins C and E and lowered cholesterol concentration in their sera. Urinary excretion of sodium is only a fraction of the omnivorous controls. Also urinary output of phenol and p-cresol is lowered as are several fecal enzyme levels which are considered harmful. The rheumatoid arthritis patients eating the LF diet reported amelioration of their pain, swelling of joints and morning stiffness which all got worse after finishing LF diet. The composite indices of objective measures showed also improvement of the rheumatoid arthritis patients during the intervention. The fibromyalgic subjects eating LF lost weight compared to their omnivorous controls. The results on their joint stiffness and pain (visual analogue scale), on their quality of sleep, on health assessment questionnaire and on general health questionnaire all improved. It appears that the adoption of vegan diet exemplified by the living food leads to a lessening of several health risk factors to cardiovascular diseases and cancer. Rheumatoid patients subjectively benefited from the vegan diet which was also seen in serum parameters and fecal analyses.     

Isolation and identification of fecal bacteria from adult swine.

An examination of the fecal microflora of adult swine was made with regard to the efficiency of several roll tube media in enumeration and recovery of anaerobes, the effects of medium constituents on recovery, and the isolation and identification of the predominant kinds of bacteria. Total number of organisms by microscopic bacterial counts varied among fecal samples from 4.48 X 10(10) to 7.40 X 10(10) bacteria/g (wet weight). Comparison of different nonselective roll tube media indicated that about 30% of the fecal bacteria could be recovered with a rumen fluid (40%, vol/vol) medium (M98-5). Recoveries of 21 and 15%, respectively, were obtained with M10 and rumen fluid-glucose-cellobiose agar (RGCA) media. Rumen fluid, Trypticase, sugars, and CO2 gas phase were important components required for maximum recovery with this medium. Similar high recoveries of anaerobes were also obtained with M98-5 containing swine cecal extract of place in rumen fluid or M10 plus swine cecal extract. Significantly lower recoveries were observed with RCGA, media supplemented with swine fecal extracts, reinforced clostridial medium, brain heart infusion agar, and prereduced blood agar. Ninety percent of the bacteria isolated from roll tube media were gram positive and consisted of facultatively anaerobic streptococci, Eubacterium sp., Clostridium sp., and Propionibacterium acnes. The remainder of the flora (8%) included several other species of anaerobes and Escherichia coli. Rumen fluid (or volatile fatty acids), Trypticase, and yeast extract additions to basal media stimulated the growth of anaerobic strains. Variation in the relative proportions of the predominant fecal microflora was observed. This work indicates that satisfactory enumeration, isolation and cultivation of the predominant microflora in swine feces can be obtained when strict anaerobic culture methods and a rumen fluid medium are used.     

基于16S rDNA测序技术分析功能性便秘患者粪便菌群

运用16S rDNA测序技术分析功能性便秘（FC）患者粪便菌群特征,以期寻找FC特征菌,为FC诊治寻找新的治疗靶点。

收集福建中医药大学附属第二人民医院60例实验组（FC患者）和30例正常组的粪便,采用16S rDNA测序技术分析粪便菌群结构,并进行基因功能的预测。

两组在门水平上,主要由厚壁菌门和拟杆菌门组成;在属水平上,主要优势菌以粪杆菌属和拟杆菌属为主。实验组粪便菌群丰富度指数Chao1、Observed_OTUs较正常组升高（P＜0.05）,多样性指数Shannon指数和Simpson指数虽有上升趋势,但差异无统计学意义（P＞0.05）。布劳特菌属、罗氏菌属、Ruminococcus_gnavus_group、Ruminococcus_gauvreauii_group、Eubacterium_hallii_group、Anaerostipes、Lachnospiraceae_ND3007_group、Dorea、乳球菌属在实验组中丰度均显著降低（P＜0.01）。实验组特征菌为小杆菌属,正常组为布劳特菌属和埃希菌−志贺菌属。实验组蔗糖降解Ⅲ（PWY-621）、丙酮酸发酵成乙酸和乳酸（PWY-5100）和琥珀酸发酵成丁酸盐（PWY-5677）功能下降（P＜0.05）。

功能性便秘患者主要表现为肠道菌群丰度与多样性升高,FC的发病可能与菌群结构发生改变有关。

     

性激素变化对小鼠肠道菌群构成的影响

肠道菌群在维持宿主免疫和消化系统功能方面发挥着重要作用,肠道菌群的多样性和丰富度是衡量宿主健康状况的重要生理指标。性激素对动物生长发育发挥重要作用,但其对肠道菌群构成影响的相关实验研究相对较少。本研究以模式生物小鼠（Mus musculus）为对象,探究性激素的变化对小鼠肠道菌群构成的影响。采用外科手术方式建立小鼠去势模型,通过16S r RNA高通量测序技术,研究性激素对小鼠肠道菌群构成的影响。研究结果表明,雌性小鼠和雄性小鼠去势后,性激素水平显著下降。肠道菌群在门水平上,正常小鼠和去势小鼠肠道细菌群落均由拟杆菌门（Bacteroidetes）、厚壁菌门（Firmicutes）、变形菌门（Proteobacteria）、埃普西隆杆菌门（Epsilonbacteraeota）、髌骨细菌门（Patescibacteria）、放线菌门（Actinobacteria）、软壁菌门（Tenericutes）、脱铁杆菌门（Deferribacteres）、酸杆菌门（Acidobacteria）和蓝藻细菌门（Cyanobacteria）组成,主要菌群为厚壁菌门和拟杆菌门物种,两门占物种相对丰度百分比...     

The use of rats associated with a human faecal flora as a model for studying the effects of diet on the human gut microflora

The activities of four bacterial biotransformation enzymes (beta-glucosidase, beta-glucuronidase, nitrate reductase and nitroreductase) were measured in the caecal contents of conventional flora rats or germ-free rats contaminated with a mixed, human faecal flora and compared with activities present in a fresh human stool preparation. Both the conventional flora rats and the rats inoculated with a human flora exhibited an enzyme profile generally similar to that of human faeces, although the conventional rat flora exhibited negligible nitrate reductase activity. The enzyme profile remained essentially unaltered in both human flora preparations following supplementation of the diet with pectin, whereas the conventional rat flora responded to this plant cell wall carbohydrate with a significant increase in nitrate reductase activity. The results demonstrate that enzymic activities of the human faecal microflora can be simulated in rats associated with a mixed population of human intestinal bacteria.     

The use of rats associated with a human faecal flora as a model for studying the effects of diet on the human gut microflora

The activities of four bacterial biotransformation enzymes (β-glucosidase, β-glucuronidase, nitrate reductase and nitroreductase) were measured in the caecal contents of conventional flora rats or germ-free rats contaminated with a mixed, human faecal flora and compared with activities present in a fresh human stool preparation. Both the conventional flora rats and the rats inoculated with a human flora exhibited an enzyme profile generally similar to that of human faeces, although the conventional rat flora exhibited negligible nitrate reductase activity. The enzyme profile remained essentially unaltered in both human flora preparations following supplementation of the diet with pectin, whereas the conventional rat flora responded to this plant cell wall carbohydrate with a significant increase in nitrate reductase activity. The results demonstrate that enzymic activities of the human faecal microflora can be simulated in rats associated with a mixed population of human intestinal bacteria.     

高核心岩藻糖基化母乳促进子代肠道双歧杆菌和乳杆菌的优势生长

目的 探究母乳蛋白核心岩藻糖基化水平对新生儿肠道菌群结构的影响。 方法 采用凝集素(aspergillus oryzae lectin,AOL)检测不同母乳样本的蛋白核心岩藻糖基化水平,按照蛋白核心岩藻糖基化水平的高低将母乳样品分为高核心岩藻糖基化组和低核心岩藻糖基化组,采集两组母乳样品对应喂养的婴儿的粪便,利用PCR-变性梯度凝胶电泳(PCR DGGE)的方法检测两组婴儿粪便中菌群的组成。利用Fut8+/-和Fut8+/+模型小鼠作为母代让其分别哺育野生型子代仔鼠,以进一步阐明核心岩藻糖基化对新生儿肠道菌群的影响。 结果 母亲/母鼠母乳蛋白岩藻糖基化水平高组与低组相比,婴儿肠道中双歧杆菌菌群丰富度增加,仔鼠肠道内乳杆菌定植增加。 结论 高核心岩藻糖基化的母乳可以促进子代肠道中双歧杆菌和乳杆菌等益生菌的生长。     

不同预处理对小鼠粪样菌群高通量测序分析结果的影响

应用高通量测序技术比较不同预处理对小鼠粪样菌群结构的影响,以期为后续相关研究提供参考依据。采集昆明小鼠新鲜粪样,分为原始粪样组、生理盐水处理组和PBS处理组,提取粪样DNA,采用Illumina MiSeq平台进行测序对3组样本的16S rRNA V3~V4区基因文库进行生物信息学分析。结果显示,3组样本拥有共同的OTUs 188个,不同预处理对粪样微生物多样性和丰度产生影响,生理盐水处理组、PBS处理组和原始粪样组分别检出14、11、12个门,3组样本共有门11个;分别检出24、21、21个纲,3组样本共有纲20个;分别检出62、55、59个科,3组样本共有科26个;分别检出147、126、137个属,3组样本共有属117个。总体来看,生理盐水处理组微生物多样性和丰度相对最高,原始粪样组次之,PBS处理组最低。粪样经生理盐水处理后,能在一定程度上提高肠道菌群检测的准确性。