Computed tomography colonography versus colonoscopy for the diagnosis of colorectal cancer: a systematic review and meta-analysis.

Colorectal cancer (CRC) is a significant cause of morbidity and mortality. Optical colonoscopy (OC) is the first choice of investigation for assessing the state of the colon and it is excellent for CRC screening. Newer technologies such as computed tomography colonography (CTC) may also be useful in CRC screening. This systematic review compares the benefits of CTC and OC for CRC screening. This review includes all the available randomized clinical trials comparing CTC and OC for CRC screening in asymptomatic patients. Three studies were included in the systematic review and were submitted for meta-analysis. In the analysis of participation rates, only 2,333 of 8,104 (29%) patients who were invited for screening underwent the CTC, and only 1,486 of the 7,310 (20%) patients who were invited for screening underwent OC. The absolute risk difference in participation rate in the two procedures was 0.1 (95% CI, 0.05-0.14) in favor of CTC. In the analysis of advanced colorectal neoplasia (ACN) detection rates, 2,357 patients undergoing CTC and 1,524 patients undergoing OC were included. Of these, 135 patients (5.7%) who underwent a CTC and 130 patients (8.5%) who underwent an OC were diagnosed with ACN. The absolute risk difference in ACN detection rate in the two procedure types was -0.02 (with a 95% CI between -0.04 and -0.00) in favor of OC. CTC is an option for CRC screening in asymptomatic patients. However, as CTC was inferior in detecting ACN, it should not replace OC, which remains the gold standard.

Gastrointestinal Transcriptomic Response of Metabolic Vitamin B12 Pathways in Roux-en-Y Gastric Bypass.

OBJECTIVES: Vitamin B12 (B12) deficiency after Roux-en-Y gastric bypass (RYGB) is highly prevalent and may contribute to postoperative complications. Decreased production of intrinsic factor owing to gastric fundus removal is thought to have a major role, but other components of B12 metabolism may also be affected. We evaluated changes in the expression levels of multiple B12 pathway-encoding genes in gastrointestinal (GI) tissues to evaluate the potential roles in contributing to post-RYGB B12 deficiency. METHODS: During double-balloon enteroscopy, serial GI biopsies were collected from 20 obese women (age, 46.9±6.2 years; body mass index, 46.5±5.3 kg/m2) with adult-onset type 2 diabetes (fasting plasma glucose ≥126 mg/dl; hemoglobin A1c≥6.5%) before and, at the same site, 3 months after RYGB. Gene expression levels were assessed by the Affymetrix Human GeneChip 1.0 ST microarray. Findings were validated by real-time quantitative PCR (RT-qPCR). RESULTS: Gene expression levels with significant changes (P≤0.05) included: transcobalamin I (TCN1) in remnant (-1.914-fold) and excluded (-1.985-fold) gastric regions; gastric intrinsic factor (GIF) in duodenum (-0.725-fold); and cubilin (CUBN) in duodenum (+0.982-fold), jejunum (+1.311-fold), and ileum (+0.685-fold). Validation by RT-qPCR confirmed (P≤0.05) observed changes for TCN1 in the remnant gastric region (-0.132-fold) and CUBN in jejunum (+2.833-fold). CONCLUSIONS: RYGB affects multiple pathway-encoding genes that may be associated with postoperative B12 deficiency. Decreased TCN1 levels seem to be the main contributing factor. Increased CUBN levels suggest an adaptive genetic reprogramming of intestinal tissue aiming to compensate for impaired intestinal B12 delivery.

Asymptomatic gastric bacterial overgrowth after bariatric surgery: are long-term metabolic consequences possible?

BACKGROUND: Patients with postbariatric bacterial overgrowth were reinvestigated after a follow-up of 15 years. It was hypothesized that systemic associations analogous to those reported for whole gut microbiome would be revealed. METHODS: Patients (n = 37, 70.3 % females, 42.4 ± 9.9 years old, preoperative BMI 53.5 ± 10.6 kg/m(2), current BMI 32.8 ± 10.8 kg/m(2)), all submitted to RYGB on account of morbid obesity, were followed during 176.8 ± 25.7 months. Blood tests included fasting blood glucose, HbA1c, liver and pancreatic enzymes, and lipid fractions. Bacterial overgrowth was diagnosed by quantitative culture of gastric fluid in both the excluded remnant and the gastric pouch, with the help of double-balloon enteroscopy. Absolute counts of aerobes and anaerobes in both gastric reservoirs were correlated with nutritional and biochemical measurements, aiming to identify clinically meaningful associations. RESULTS: Patients denied diarrhea, abdominal pain, weight loss, or other symptoms related to bacterial overgrowth. Biochemical profile including enzymes was also acceptable, indicating a stable condition. Positive correlation of bacterial count in either segment of the stomach was demonstrated for BMI and gamma-glutamyl transferase, whereas negative correlation occurred regarding fasting blood glucose. CONCLUSIONS: An antidiabetic role along with deleterious consequences for weight loss and liver function are possible in such circumstances. Such phenotype is broadly consistent with reported effects for the whole gut microbiome. Prospective controlled studies including molecular analysis of gastrointestinal fluid, and simultaneous profiling of the entire microbiome, are necessary to shed more light on these findings.

Endoscopic findings in the excluded stomach after Roux-en-Y gastric bypass surgery.

HYPOTHESIS: After gastric bypass surgery performed because of morbid obesity, the excluded stomach can rarely be endoscopically examined. With the advent of a new apparatus and technique, possible mucosal changes can be routinely accessed and monitored, thus preventing potential benign and malignant complications. DESIGN: Prospective observational study in a homogeneous population with nonspecific symptoms. SETTING: Outpatient clinic of a large public academic hospital. PATIENTS: Forty consecutive patients (mean +/- SD age, 44.5 +/- 10.0 y ears; 85.0% women) were seen at a mean +/- SD of 77.3 +/- 19.4 months after Roux-en-Y gastric bypass surgery. INTERVENTION: Elective double-balloon enteroscopy of the excluded stomach was performed. MAIN OUTCOME MEASURES: Rate of successful intubation, endoscopic findings, and complications. RESULTS: The excluded stomach was reached in 35 of 40 patients (87.5%). Mean +/- SD time to enter the organ was 24.9 +/- 14.3 minutes (range, 5-75 minutes). Endoscopic findings were normal in 9 patients (25.7%), whereas in 26 (74.3%), various types of gastritis (erythematous, erosive, hemorrhagic erosive, and atrophic) were identified, primarily in the gastric body and antrum. No cancer was documented in the present series. Tolerance was good, and no complications were recorded during or after the intervention. CONCLUSIONS: The double-balloon method is useful and practical for access to the excluded stomach. Although cancer was not noted, most of the studied population had gastritis, including moderate and severe forms. Surveillance of the excluded stomach is recommended after Roux-en-Y gastric bypass surgery performed because of morbid obesity.

Increased gastric cytokine production after Roux-en-Y gastric bypass for morbid obesity.

HYPOTHESIS: Mucosal cytokines may be involved in the process of gastric bacterial contamination that may occur after Roux-en-Y bypass for morbid obesity in both gastric chambers, with inflammation and gastritis mostly in the excluded stomach. DESIGN: A prospective observational study in a homogeneous population with nonspecific complaints. SETTING: Outpatient clinic of a large, public, academic hospital. PATIENTS: Subjects (n = 37; 26 [70.3%] female; mean +/- SD age, 42.4 +/- 9.9 years) seen a mean +/- SD of 7.3 +/- 1.4 years after Roux-en-Y gastric bypass and nonoperated on morbidly obese control subjects (n = 10; 7 [70%] female; mean +/- SD age, 44.0 +/- 8.9 years). INTERVENTION: Enteroscopy was performed to collect samples for cytokine assays and bacteriologic studies. MAIN OUTCOME MEASURES: Concentrations of tumor necrosis factor alpha and transforming growth factor beta in the gastric mucosa of both chambers in patients undergoing Roux-en-Y gastric bypass and correlation with bacterial overgrowth and Helicobacter pylori infection. RESULTS: High microbial counts (>10(5) colony-forming units per milliliter) were detected in 22 (59.5%) and 7 (18.9%) of the 37 samples from the functional pouch and excluded reservoir, respectively; and H pylori investigation was positive in 6 of 37 samples (16.2%). The tumor necrosis factor alpha concentration (mean +/- SD, 2.1 +/- 1.9 pg/g of protein) and the transforming growth factor beta concentration (mean +/- SD, 24.2 +/- 12.8 pg/g of protein) in the excluded stomach, but not in the proximal pouch, were elevated with regard to the corpus or antrum of controls, and correlation with bacterial overgrowth and with H pylori infection was demonstrated. CONCLUSION: Overexpression of tumor necrosis factor alpha and transforming growth factor beta occurred in the distal stomach, positive cytokine correlation with microbial invasion by H pylori and nonspecific germs was seen, and further studies addressing phenotypic and genotypic changes of gastric mucosa are recommended.

Microbial flora of the stomach after gastric bypass for morbid obesity.

BACKGROUND: The normal stomach is virtually sterile but the effect of Roux-en-Y gastric bypass (RYGBP) on bacterial flora in the used (very small proximal pouch) and unused (large bypassed) gastric chambers is not known. In a prospective study, this variable was documented. METHODS: Bariatric subjects (n=37) were submitted to endoscopic examination of both gastric reservoirs via FUJINON enteroscope model EN-450P5, 7.3 +/- 1.4 years after RYGBP. Age was 42.4 +/- 9.9 years (70.2% females), preoperative BMI was 53.5 +/- 10.6, and current BMI was 32.6 +/- 7.8 kg/m2. Methods included quantitative culture of gastric secretion along with gastric pH and lactulose/hydrogen breath test. RESULTS: None of the subjects displayed diarrhea, malabsorption or other complaints suggestive of GI bacterial overgrowth. Elevated counts of bacteria and fungi were identified in both chambers, with predominance of aerobes and anaerobes, but not molds and yeasts, in the proximal stomach. Gram-positive cocci, bacilli and coccobacilli represented the majority of the isolates. Gastric pH was neutral (pH 7.0 +/- 0.2) in the proximal pouch, whereas the distal chamber mostly but not always conserved the expected acidity (pH 3.3 +/- 2.2, P<0.001). The breath test for bacterial overgrowth was positive in 40.5% of the population. CONCLUSIONS: 1) Frequent colonization of both gastric chambers was detected; 2) Aerobes, anaerobes and fungi were represented in both situations; 3) Gastric pH as well as bacterial count was higher in the functioning proximal stomach; 4) Breath test was positive in 40.5% of the subjects; 5) Clinical manifestation such as diarrhea, malabsorption or pneumonia were not demonstrated; 6) Further histologic and microbiologic studies of both the stomach and the small bowel are recommended.

Systemic inflammation in morbidly obese subjects: response to oral supplementation with alpha-linolenic acid.

BACKGROUND: Morbidly obese patients frequently display asymptomatic chronic activation of acute phase response, with potentially adverse metabolic and cardiovascular consequences. Nutritional preparations to improve this phenomenon have rarely been administered. Aiming to investigate the supplementation of flaxseed flour, a source of omega-3 fatty acids, a prospective randomized double-blind cross-over study was designed. METHODS: Outpatient obese subjects (n=41) were clinically and biochemically screened, and results for 24 randomized subjects are shown. Age was 40.8 +/- 11.6 years (83.3% females) and body mass index (BMI) was 47.1 +/- 7.2 kg/m2. Flaxseed flour (Farinha de Linhaca Dourada LinoLive, Cisbra, Brazil) in the amount of 30 g/day (5 g of alpha-linolenic acid - omega-3) and an equal mass of placebo (manioc flour) were administered for 2 weeks each. Variables included general biochemical investigation, white blood cell count (WBC), C-reactive protein (CRP), serum amyloid A (SAA) and fibronectin. RESULTS: No intolerance was registered. Body weight and general biochemical indices remained stable. Initial CRP and SAA were elevated (13.7 +/- 9.9 and 17.4 +/- 8.0 ). WBC (8100 +/- 2100/mm3) and fibronectin (463.2 +/- 61.3 mg/dL) were acceptable but in the upper normal range. Corresponding findings after supplementation of flaxseed were 10.6 +/- 6.2 mg/L, 14.3 +/- 9.2 mg/L, 7300 +/- 1800/mm3 and 412.8 +/- 38.6 respectively (P<0.05). No change during the control period regarding baseline occurred when placebo was randomized to be given first; however, when it followed omega-3 supplementation, CRP and SAA recovered, whereas WBC and fibronection remained depressed during those 2 weeks (7500 +/- 2100/mm3 and 393.2 +/- 75.8 mg/dL, P<0.05). CONCLUSIONS: 1) Various inflammatory markers were elevated in the studied population, although not necessarily exceeding the normal range; 2) Significant reduction could be demonstrated; 3) Some persistent effects of flaxseed supplement 2 weeks after discontinuation were observed.

What to expect in the excluded stomach mucosa after vertical banded Roux-en-Y gastric bypass for morbid obesity.

Mucosal alterations after vertical banded Roux-en-Y gastric bypass have not been clearly evaluated. The aim of this paper was to analyze the histological findings and the presence of Helicobacter pylori in the excluded stomach. Forty consecutive patients who underwent Roux-en-Y gastric bypass longer than 36 months were selected for double-balloon enteroscopy. The excluded stomach was reached in 35/40 patients (88%). Morphological alterations were analyzed through hematoxilin and eosin and the presence of H. pylori was confirmed with Giemsa staining. Thirty patients (86%) were female, and the mean age was 43 years old. The mean postoperative time was 78 months (36-110 months). Histologically, all patients had chronic gastritis in the bypassed stomach, with pangastritis in 33/35 (94%). Five cases (5/35, 14%) presented atrophy and four of them also had intestinal metaplasia. Helicobacter pylori was detected in 7/35 (20%) of the excluded stomach and in 12/35 (34%) of the functional pouch. All patients positive for H. pylori in the excluded stomach were also positive in the functional pouch, p = 0.0005. Helicobacter pylori is still present in the excluded stomach after Roux-en-Y gastric bypass and might be considered for treatment. Histological findings indicated high prevalence of atrophy and intestinal metaplasia in this selected population.