二甲双胍对直肠异常隐窝病灶抑制作用的研究

[目的]探讨二甲双胍对直肠异常隐窝病灶(Aberrant Crypt Foci,ACF)的抑制作用及其可能机制。[方法]入选经消化内镜发现直肠ACF的非糖尿病患者86例,随机分成二甲双胍组、塞来昔布组及对照组。二甲双胍组口服二甲双胍500 mg 2次/d,塞来昔布组口服塞来昔布200 mg 2次/d,对照组不服用二甲双胍及塞来昔布。在治疗前及治疗后2个月行肠镜检查,予0.4%美兰染色直肠,用放大肠镜观察直肠中亨氏瓣到齿状线之间的ACF个数及形态,分析各组直肠ACF个数在治疗前、后的变化。同时用活检钳在直肠上亨氏瓣到中亨氏瓣之间随机取得直肠正常黏膜处的标本,应用PCNA(proliferating cell nuclear antigen)免疫组化染色及TUNEL(transferase deoxynucleotidyl uridine end labeling)染色法检测直肠正常黏膜的增殖及凋亡情况。[结果]3组治疗前ACF均数及临床特征比较均差异无统计学意义(P0.05)。二甲双胍组、塞来昔布组的ACF均数分别从治疗前的7.30±2.51、7.60±2.34减少至治疗后的4.77±1.57、5.83±1.46(P0.05),且相对于塞来昔布组,二甲双胍组对ACF的抑制作用更明显(P0.05)。对照组的ACF均数在治疗前后分别为7.40±2.11、7.43±2.13,差异无统计学意义(P0.05)。二甲双胍组、塞来昔布组的增殖指数分别从治疗前的48.87±1.78、49.93±2.59减少至治疗后的27.20±1.71、36.97±1.43(P0.05),且二甲双胍组显著低于塞来昔布组(P0.05)。对照组的增殖指数在治疗前后分别为49.17±2.35、49.23±2.42,差异无统计学意义(P0.05)。3组治疗后的凋亡指数分别为3.00±1.14、2.93±0.78、3.07±1.08,与本组治疗前相比均差异无统计学意义(P0.05)。[结论]二甲双胍及塞来昔布对非糖尿病患者的直肠ACF均具有抑制作用,且二甲双胍的作用优于塞来昔布,其机制可能是通过直接作用(非胰岛素依赖)来抑制组织细胞的增殖。     

塞来昔布对二甲基肼诱导的大鼠畸变隐窝灶的预防作用

目的　明确塞来昔布 (选择性COX 2抑制剂 )对二甲基肼 (DMH)诱导的大鼠畸变隐窝灶(ACF)的化学预防作用 ,并与舒林酸 (一种非甾体类抗炎药 )进行比较。方法　 32只 8周龄雌性SD大鼠 ,随机分为 4组 ,每组 8只。第 1组单次腹腔注射DMH(每千克体重 12 0mg) ;第 2组单次腹腔注射生理盐水 (1ml/只 ) ;第 3组先舒林酸 (每千克饲料 32 0mg)喂养 7d ,然后注射DMH ;第 4组先塞来昔布(每千克饲料 15 0 0mg)喂养 7d ,然后注射DMH。注射DMH 5周后处死大鼠 ,美蓝染色后计数每只大鼠大肠中ACF和畸变隐窝 (AC)个数。结果　第 1组平均每只大鼠结肠中ACF和AC分别为 (182 .4 0± 93.4 3)和 (2 6 2 .80± 197.80 )个。第 2组没有发现ACF。第 3组ACF和AC分别为 (91.2 5± 4 8.98)和(139.6 0± 6 8.5 2 )个 ,与第 1组相比差异有显著性 (P <0 .0 5 )。第 4组ACF和AC分别为 (6 5 .83± 38.5 4 )和 (10 6 .0 0± 6 1.0 3)个 ,与第 1组相比差异有显著性 (P <0 .0 1)。第 3组与第 4组相比 ,ACF及AC个数差异无显著性。结论　选择性COX 2抑制剂塞来昔布对实验诱导的大鼠ACF具有预防作用 ,其作用与舒林酸相当。     

直肠异常隐窝病灶对结肠肿瘤的预警作用

目的 评判内镜下直肠异常隐窝病灶(ACF)与结肠病变及高癌变潜能肿瘤(AN)的关系.方法 接受全结肠镜检查的正常、息肉、腺瘤及癌的患者212例,在退镜时用0.4%靛胭脂对直肠进行染色,根据直肠ACF的数目对患者分级,无ACF者为0级,ACF数目为1～4,5～9,≥10者分别为Ⅰ、Ⅱ、Ⅲ级,统计分析ACF级别与结肠病变(息肉、腺瘤和癌),高癌变潜能肿瘤(≥1 cm,绒毛状、管状绒毛状,高度异型增生或浸润癌)的关系.结果 212例患者中,72例直肠ACF为0级,48例为Ⅰ级,41例为Ⅱ级,51例为Ⅲ级.直肠有ACF(包括Ⅰ、Ⅱ、Ⅲ级)的患者发生结肠病变及结肠高癌变潜能肿瘤的概率较无ACF者明显升高,其OR值(95%CI)分别为22.352(6.716～74.395),7.982(1.838～34.672).结论 直肠ACF对结肠病变及高癌变潜能肿瘤有预示作用.     

二甲双胍、塞来昔布对小鼠结直肠息肉预防作用的比较

[目的]比较二甲双胍、塞来昔布对氧化偶氮甲烷(AOM)诱导的小鼠结直肠息肉的预防作用。[方法]66只6周龄BALB/c雌性小鼠适应1周后予腹腔注射AOM(10mg/kg),每周1次,连续6周;后随机分为对照组、二甲双胍组、塞来昔布组,对照组、二甲双胍组、塞来昔布组分别予0.9%氯化钠溶液(0.5ml/只)、二甲双胍250mg·kg~(-1)·d~(-1)、塞来昔布20mg·kg~(-1)·d~(-1)灌胃处理。30周后取出小鼠结直肠记录小鼠结直肠息肉发生的数目、大小,通过PCNA免疫组化染色及TUNEL染色检测息肉组织的增殖及凋亡的情况;检测小鼠胰岛素的抵抗状态以评估二甲双胍的间接作用。[结果]二甲双胍组小鼠息肉数量为(1.85±0.80)个,塞来昔布组小鼠息肉数量为(3.00±0.93)个,均较对照组的(4.13±1.06)个少(P0.05);二甲双胍组息肉大小为(1.74±0.48)mm,塞来昔布组为(2.07±0.88)mm,也均较对照组的(2.54±0.82)mm小(P0.05);与塞来昔布组相比,二甲双胍组可更加显著地减少AOM诱导的息肉的数量(P0.05),但塞来昔布组与二甲双胍组间息肉大小比较差异无统计学意义(P0.05);对照组增殖指数(PI)为67.50±5.04,高于二甲双胍组和塞来昔布组的37.90±3.48和46.10±6.19(P0.05),且二甲双胍组显著低于塞来昔布组(P0.05);对照组凋亡指数(AI)为3.60±1.17,低于二甲双胍组、塞来昔布组的6.20±1.40、5.80±1.03(P0.05);另外,经二甲双胍、塞来昔布治疗后的小鼠胰岛素抵抗指数与对照组相比未出现明显的改变(P0.05)。[结论]二甲双胍、塞来昔布均对AOM诱导的小鼠结直肠息肉具有预防作用,且二甲双胍的预防作用更显著,预防效果更稳定。     

二甲双胍对糖耐量异常患者的治疗作用观察

目的观察二甲双胍对糖耐量减低（IGT）患者的治疗效果。方法98例IGT患者采用随机双盲法分成二甲双胍组和安慰剂组,观察两组二甲双胍和安慰剂干预治疗2a后空腹血糖（FPG）及葡萄糖耐量试验（OGTT）后2h血糖（2hPG）、总胆固醇（TC）、甘油三酯（TG）、低密度脂蛋白（LDL）、高密度脂蛋白（HDL）、胰岛素抵抗指数、空腹胰岛素（FINS）和OGTT后2h胰岛素（2hPINS）水平的变化。结果干预治疗2a后,二甲双胍组与安慰剂组比较FPG、2hPG、TC、TG、LDL、FINS及2hPINS均明显下降（P〈0．05）;安慰剂组糖尿病的发病率为18．4％,二甲双胍组糖尿病的发病率为4．1％,两组比较差异有统计学意义（P〈0．05）。结论二甲双胍能够降低IGT人群糖尿病的发病率,减轻胰岛素抵抗的同时,可使IGT明显改善。     

二甲双胍对2型糖尿病合并结直肠癌患者预后的影响

目的 探讨T2DM合并结直肠癌患者的临床病理特征和二甲双胍对肿瘤分化程度及转移的影响.方法 检测研究对象FPG、血白蛋白（Alb）、BUN、血肌酐（Scr）、血尿酸（SUA）、TG、TC、HDL-C、LDL-C和极低密度脂蛋白胆固醇（VLDL-C）水平,观察结直肠癌病理分级、结直肠癌淋巴结及远处转移情况. 结果 按照患者诊断结直肠癌时是否服用二甲双胍进行分组后发现,二甲双胍组低分化腺癌比例及远处转移率均低于无二甲双胍组（P＜0.05）. 结论 T2DM合并结直肠癌患者口服二甲双胍降糖,其肿瘤预后较好.     

直肠异常隐窝病灶对大肠癌和进展型腺瘤的预警作用及其危险因素分析

目的 探讨直肠异常隐窝病灶（ACF）对大肠癌及进展型腺瘤的预警作用,并分析其危险因素.方法 应用独立样本t检验、单向方差分析及卡方检验分析比较直肠ACF的均数及发病率,应用Logistic回归分析直肠ACF与大肠癌及进展型腺瘤的关系,观察是否有预警作用,并筛选对ACF有显著意义的危险因素.结果 5个以上ACF显著增加大肠癌及进展型腺瘤的风险（P＜0.05）;高龄和吸烟为ACF的危险因素,而阿司匹林的应用为其保护因素.结论 5个以上ACF对大肠癌及进展型腺瘤有显著预警作用.在大肠癌的早期预防中,我们应该重视对ACF的形成有意义的影响因素.     

二甲双胍对合并高血压的糖耐量异常的干预研究

对144例合并高血压的IGT患者随机分为生活方式控制组（LC）,生活方式控制加二甲双胍组（LC＋M）两组,分析干预12月后各组IGT转化为正常糖耐量NGT和新发糖尿病的发生率以及高血压高血压与IGT、NGT、DM之间的关系。结果：两组干预治疗后,2hpG均明显降低（P〈0．01）与LC组比LC＋M组转化为NGT的人数明显增多（P〈0．01）,并且血压越达标,糖尿病发病率越低。结论：对伴有IGT的高血压患者,二甲双胍的干预可减少糖尿病的发生。     

二甲双胍与结直肠腺瘤患病风险相关性的荟萃分析

目的探索糖尿病患者服用二甲双胍是否可降低患结肠直肠腺瘤的风险。 方法从PubMed、Elsevier-ScienceDirect、万方、维普数据库中检索建库以来至2017年7月所有关于2型糖尿病患者使用二甲双胍与患结直肠腺瘤风险相关性的研究。按照纳入及排除标准选择入选。 结果共计纳入9项研究,其中实验组4 256例,对照组17 206例,结果显示,服用二甲双胍者较未服用二甲双胍者患结直肠腺瘤风险降低（OR=0.83,95%CI：0.72~0.95;P=0.008）,差异具有统计学意义。 结论二甲双胍的使用可能与结肠直肠腺瘤的风险降低有关。     

塞来昔布对大鼠溃疡性结肠炎的作用

目的观察塞来昔布对三硝基苯磺酸(TNBS)灌肠诱发结肠炎的大鼠的血清前列腺素E2(prostagland E2,PGE2)及结肠组织COX-2水平影响,并探讨塞来昔布对溃疡性结肠炎(ulcerative colitis,UC)的作用及作用机制。方法 Wistar雄性大鼠40只,随机分成4组,每组10只,A组为正常对照组(未经任何处理)、B组为水杨酸偶氮磺胺吡啶(salicylazosulfapyridine,SASP)组、C组为塞来昔布组、D组为模型对照组(0.9%氯化钠注射液)。B、C、D三组均采用TNBS/乙醇灌肠制作大鼠UC模型后,B组SASP 200 mg/kg、C组塞来昔布10 mg/kg、D组0.9%氯化钠注射液1 ml每天灌胃给药1次,连续治疗7 d后处死所有存活大鼠。在造模成功后每天评定各组大鼠一般状况、DAI(disease activity index)评分;药物治疗后第7天在全麻下心脏采血,采用酶联免疫吸附法(ELISA)检测血清PGE2浓度,取病变组织行HE染色和COX-2免疫组织化学染色。结果 B组和C组一般情况及消化道症状好于D组。C组DAI评分高于B组(P<0.01),与D组相接近(P=0.418),无显著性差异。A组(75.28±7.55)血清PGE2含量表达量均明显少于其他三组(P<0.05)。C组血清PGE2含量表达少于B组、D组(P<0.01)。结论塞来昔布对TNBS诱导的UC无明显治疗作用。虽然塞来昔布可以使TNBS诱发的肠炎大鼠结肠病变处的炎症减轻,使血清PGE2等炎症相关因子表达减少,但未能明显减轻UC肠黏膜的损害,甚至有加重疾病症状的倾向,因此,塞来昔布能否用于UC的治疗仍然有待进一步研究。     

Role of aberrant crypt foci detected using high-magnification-chromoscopic colonoscopy in human colorectal carcinogenesis

Abstract Liaison between gastrointestinal endoscopists and histopathologists is essential to provide the highest standards of diagnostic accuracy and patient management. The histopathologist needs to be aware of the endoscopic findings when interpreting endoscopic biopsies. High-magnification-chromoscopic-colonoscopy (HMCC) is a new technology that provides the endoscopists with much greater resolution and functional staining of the gastrointestinal tract. Using HMCC, the endoscopist is now able to identify subtle changes in the colorectal luminal openings or crypts. Changes in crypt appearances now allow detection of aberrant crypt foci (ACF) in the colon, which might themselves be precancerous lesions but additionally might serve as a valid biomarker of subsequent adenoma and colorectal cancer formation. This article describes the role of the aberrant crypt focus in colorectal carcinogenesis and discusses the clinical impact of HMCC techniques as applicable to ACF.     

Number of aberrant crypt foci in the rectum is a useful surrogate marker of colorectal adenoma recurrence

Aim: Endoscopic screening and removal of colorectal adenomas can reduce the incidence of colorectal cancer. However, given the possibility of adenoma recurrence, surveillance colonoscopy is currently recommended after the initial screening and removal of colorectal adenomas. Aberrant crypt foci (ACF) have been shown to serve as a reliable surrogate marker of colorectal carcinogenesis. In this study, the relationship between the number of ACF at the initial endoscopic polypectomy and the likelihood of colorectal adenoma recurrence after polypectomy were investigated. Methods: High‐magnification chromoscopic colonoscopy was performed in 82 subjects who underwent endoscopic polypectomy to identify ACF in the lower rectum. Surveillance colonoscopy was then performed 3 years after the baseline polypectomy at Yokohama City University Hospital. Results: The number of ACF was greater in patients who showed adenoma recurrence (7.88 ± 6.35) than in those who did not (2.19 ± 2.95) (P < 0.001). Receiver–operating curve analysis showed that the number of ACF was a highly specific predictor of the risk of adenoma recurrence. Conclusions: This is the first study conducted to investigate the relationship between the number of ACF after endoscopic polypectomy and the likelihood of recurrence of colorectal adenomas. These results suggest that the number of ACF is a useful predictor of the likelihood of colorectal adenoma recurrence.     

APC and K-ras gene mutation in aberrant crypt foci of human colon

AIM To study the genetic alteration in ACF andto define the possibility that ACF may be a veryearly morphological lesion with molecularchanges,and to explore the relationshipbetween ACF and colorectal adenoma evencarcinoma.METHODS DNA from 35 CRC,15 adenomas,34ACF and 10 normal mucus was isolated by meansof microdissection.Direct gene sequencing of K-ras gene including codon 12,13 and 61 as well asthe mutation cluster region(MCR)of APC genewas performed.RESULTS K-ras gene mutation frequency inACF,adenoma and carcinoma was 17.6%(6/34),13.3%(2/15),and 14.3%(5/35)respectively,showing no difference(P>0.05)in K-ras gene mutation among three pathologicprocedures.The K-ras gene mutation inadenoma,carcinoma and 4 ACF restricted incodon 12(GGT→GAT),but the other 2 mutationsfrom ACF located in codon 13(GGC→GAC).K-ras gene mutation was found more frequently inolder patients and patients with polypoidcancer.No mutation in codon 61 was found in thethree tissue types.Mutation rate of APC gene inadenoma and carcinoma was 22.9%(8/35)and26.7%(4/15),which was higher than ACF(2.9%)(P<0.05).APC gene mutation incarcinoma was not correlated with age ofpatients,location,size and differentiation oftumor.CONCLUSION ACF might be a very early morphological lesion in the tumorogenesis ofcolorectal tumor.The morphological feature andgene mutation status was different in ACF andadenoma.ACF is possibly putative“microadenoma”that might be the precursor ofadenoma.In addition,the development of asubgroup of colorectal carcinomas mightundergo a way of“normal epithelium→ACF→carcinomas”.     

Polyethylene glycol,unique among laxatives,suppresses aberrant crypt foci,by elimination of cells

Objective. Polyethylene glycol (PEG), an osmotic laxative, is a potent inhibitor of colon cancer in rats. In a search for the underling mechanisms, the hypothesis that fecal bulking and moisture decrease colon carcinogenesis was tested. We also investigated the PEG effects on crypt cells in vivo.

Material and methods. Fischer 344 rats (n=272) were injected with the colon carcinogen, azoxymethane. They were then randomized to a standard AIN76 diet containing one of 19 laxative agents (5% w/w in most cases): PEG 8000 and other PEG-like compounds, carboxymethylcellulose, polyvinylpyrrolidone, sodium polyacrylate, calcium polycarbophil, karaya gum, psyllium, mannitol, sorbitol, lactulose, propylene glycol, magnesium hydroxide, sodium phosphate, bisacodyl, docusate, and paraffin oil. Aberrant crypt foci (ACF) and fecal values were measured blindly after a 30-day treatment regimen. Proliferation, apoptosis, and the removal of cells from crypts were studied in control and PEG-fed rats using various methods, including TUNEL and fluorescein dextran labeling.

Results. PEG 8000 reduced the number of ACF 9-fold in rats (p<0.001). The other PEGs and magnesium hydroxide modestly suppressed ACF, but not the other laxatives. ACF number did not correlate with fecal weight or moisture. PEG doubled the apoptotic bodies per crypt (p<0.05), increased proliferation by 25–50% (p<0.05) and strikingly increased (>40-fold) a fecal marker of epitheliolysis in the gut (p<0.001). PEG normalized the percentage of fluorescein dextran labeled cells on the top of ACF (p<0.001).

Conclusions. Among laxatives, only PEG afforded potent chemoprevention. PEG protection was not due to increased fecal bulking, but in all likelihood to the elimination of cells from precancerous lesions.     

Folate deficiency diminishes the occurrence of aberrant crypt foci in the rat colon but does not alter global DNA methylation status

BACKGROUND AND AIMS: It has been suggested that a diminished folate status may enhance colorectal carcinogenesis by causing DNA hypomethylation. The aims of the present study were to assess the impact of different levels of folate depletion on azoxymethane (AOM)-induced aberrant crypt foci (ACF) formation and DNA hypomethylation in the colon of male Sprague-Dawley rats. METHODS: Rats, aged 4 weeks, were divided into four groups and were fed semipurified diets either containing adequate folate (control), devoid of folate (FD) or FD + 1% succinylsulfathiazole before AOM treatment (FD1) or during the last 4 weeks of the study (FD2). At 8 weeks of age, all animals received subcutaneous injections of AOM once weekly for 3 weeks at a dose rate of 15 mg/kg bodyweight. Animals were necropsied 6 weeks after the last AOM injection and the ACF were visualized under light microscopy in formalin-fixed, methylene blue-stained colons. RESULTS: Blood folate concentrations were significantly depleted (P < 0.001) in the treatment groups consuming folate deplete diets, with the FD2 treatment group having significantly lower folate levels compared with all other groups. Higher plasma homocysteine concentrations (P < 0.001) were observed in the groups that exhibited diminished blood folate levels. There were no significant differences in global DNA methylation in the liver or colonic mucosa between the four groups, despite some groups exhibiting marked folate depletion. Animals with the most severe folate deficiency (FD2) had a lower final bodyweight and had significantly fewer ACF in their colon (P < 0.05) compared with control animals. Total (mean +/- SEM) ACF counts were as follows: control 286+/-24; FD 290+/-25; FD1 218+/-32; and FD2 205+/-27. CONCLUSIONS: In this model, folate deficiency diminished the occurrence of ACF but did not alter global DNA methylation status in the colon.     

Only fibres promoting a stable butyrate producing colonic ecosystem decrease the rate of aberrant crypt foci in rats

BACKGROUND: Dietary fibres have been proposed as protective agents against colon cancer but results of both epidemiological and experimental studies are inconclusive. AIMS: Hypothesising that protection against colon cancer may be restricted to butyrate producing fibres, we investigated the factors needed for long term stable butyrate production and its relation to susceptibility to colon cancer. METHODS: A two part randomised blinded study in rats, mimicking a prospective study in humans, was performed using a low fibre control diet (CD) and three high fibre diets: starch free wheat bran (WB), type III resistant starch (RS), and short chain fructo-oligosaccharides (FOS). Using a randomised block design, 96 inbred rats were fed for two, 16, 30, or 44 days to determine the period of adaptation to the diets, fermentation profiles, and effects on the colon, including mucosal proliferation on day 44. Subsequently, 36 rats fed the same diets for 44 days were injected with azoxymethane and checked for aberrant crypt foci 30 days later. RESULTS: After fermentation had stabilised (44 days), only RS and FOS produced large amounts of butyrate, with a trophic effect in the large intestine. No difference in mucosal proliferation between the diets was noted at this time. In the subsequent experiment one month later, fewer aberrant crypt foci were present in rats fed high butyrate producing diets (RS, p=0.022; FOS, p=0.043). CONCLUSION: A stable butyrate producing colonic ecosystem related to selected fibres appears to be less conducive to colon carcinogenesis.