Faculty Bibliography

Glanzmann's thrombasthenia (GT) is a rare autosomal recessive bleeding syndrome characterized by abnormal Glycoprotein IIb/IIIa complex (GIIb/IIIa) on platelets with resultant abnormality in platelet aggregation. There is very little information regarding polypectomy management in GT. We report a single patient with this rare disease, who underwent sequential endoscopic management of large colon polyps. Polypectomy in our GT patient was complicated by immediate and delayed bleeding. Multiple clips used after standard cautery polypectomy for a polyp 10 mm or larger in our GT patient, was most effective in preventing immediate and delayed post-polypectomy bleeding than other known therapeutic approaches. We favor preemptive use of multiple clips in large polypectomy defects for GT patients and we may argue the added cost may be offset by the reduction in the need for blood products, and by averting or shortening potential hospitalizations.

Fat infiltration and inflammation cause liver injury and fibrosis and may progress to nonalcoholic steatohepatitis (NASH) and end-stage liver disease. Currently, there are no effective treatments for NASH. Zeaxanthin is a carotenoid which has been shown to be preferentially accumulated in the adipose tissue and liver. We hypothesized that treatment with zeaxanthin may decrease oxidative stress in the liver and, possibly, halt the inflammation and fibrosis associated with NASH. Here we tested zeaxanthin effects in preventing progression of liver injury in a model of NASH. Mongolian gerbils, fed a methionine-choline-deficient diet, were treated with different doses of zeaxanthin. We assessed histopathological changes by hematoxylin-eosin and Masson trichrome staining and determined oxidative stress by measuring lipid peroxidation. The obtained results show that zeaxanthin significantly prevented NASH progression by decreasing oxidative stress and liver fibrosis, thus suggesting a potential therapeutic application for this carotenoid in the management of NASH.

The aim of this study was to investigate whether an oral sodium phosphate solution (OSPS) mixed with aspartame-based clear liquids as the diluent would yield improved colon cleansing results compared to an OSPS mixed with sucrose-based liquids as the diluent. Fifty-one patients undergoing colonoscopy were prospectively randomized into two groups to receive different OSPS colonoscopy preparations, with sucrose-based or aspartame-based liquids used as diluents. The primary end point was the quality of the colonoscopy preparation and secondary end points were serum electrolytes before and after preparations. No significant difference in colonoscopy preparation quality was seen between the two OSPS diluent groups (Mantel-Haenzel chi (2) = 0.795, P = 0.484). There were no significant differences in mean electrolyte shifts of sodium, potassium, blood urea nitrogen (BUN), creatinine (Cr), or BUN/Cr ratios between the two groups. There was a statistically significant increase in serum phosphorous in the aspartame-based group compared to the sucrose-based diluent group (P = 0.021). In conclusion, there was no clinically detectable difference in colonoscopy preparation quality between the two OSPS diluent groups. This study suggests that passive fluid transport by aquaporins may well be the major mediator of fluid shifts in the study subjects. This result suggests the potential importance of aquaporins and minimizes the importance of sodium glucose cotransporter SGLT1 in fluid and electrolyte transport in the human gastrointestinal tract. Aspartame or its constituent amino acids may enhance phosphate absorption across the human small intestine.

BACKGROUND AND STUDY AIMS/OBJECTIVE:Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disorder characterized by telangiectasia formation that can lead to small-bowel bleeding. In this study, video capsule endoscopy was used to compare the small-bowel findings observed in patients with HHT with those seen in patients without the condition. PATIENTS AND METHODS/METHODS:We performed capsule endoscopy studies in 93 consecutive patients who were being evaluated for small-bowel bleeding, 38 patients with known or suspected HHT and 55 patients without HHT. Nine patients were excluded because the capsule failed to reach the cecum. The findings in 32 patients with a final diagnosis of HHT and in 48 patients without HHT were recorded and compared. RESULTS:Capsule endoscopy detected telangiectases evenly distributed throughout the small bowel in 26/32 (81%) patients with HHT, compared with 14/48 (29%) in patients without HHT. When active bleeding was observed in patients with HHT (n = 4), the bleeding was within reach of standard small-bowel push enteroscopy in all cases. The presence of five or more gastrointestinal telangiectases by capsule endoscopy had a sensitivity of 75% and a positive predictive value of 86% for diagnosing HHT. Unexpected findings (small-bowel polyps and mass-like lesions) were seen in both groups of patients (6.2% in patients with HHT and 2.1% in patients without HHT). CONCLUSIONS:Small-bowel telangiectases were seen in the majority of patients with HHT and were evenly distributed throughout the small bowel. Telangiectases were observed in only a minority of patients who did not have HHT. Actively bleeding small-bowel telangiectases were located in the proximal and mid-small bowel in patients with HHT, all within reach of an enteroscope. We propose a cutoff point of at least five gastrointestinal telangiectases to support a diagnosis of HHT.

We present four cases of gastrointestinal granular cell tumors (GCT) with a literature review. Gastrointestinal granular cell tumors, a benign neural tumor thought to arise from Schwann cells, can occur in several areas, including the gastrointestinal tract. Studies suggest that endoscopic ultrasound and endoscopic removal is the treatment of choice for esophageal GCTs if they are small in size (< 2 cm) and do not involve the muscularis propria. GCTs are malignant less than 2% of the time. Although most GCTs are benign and can be followed endoscopically without resection, the malignant potential warrants evaluation with endoscopic ultrasound for possible endoscopic or surgical resection.

We have reported that transfer of chromosome 3 (Chr3) containing a single wild-type copy of the hMLH1 gene into HCT116 colon cancer cells, a cell line deficient in DNA mismatch repair (MMR) activity attributable to inactivating hMLH1 mutations, corrects all of the aspects of the MMR repair-deficient phenotype. We inhibited the expression of the wild-type hMLH1 gene using antisense RNA in HCT116+Chr3 cells to determine if this would result in reversion to the MMR-deficient phenotype. Despite profound inhibition of hMLH1 expression, DNA MMR activity and alkylation sensitivity were not impaired in the antisense-transfected HCT116+Chr3 cells. Additionally, arrest of the cell cycle at the G2 phase with alkylation damage occurs in these cells, a phenotype associated with MMR proficiency. These results indicate that even with a reduction in the expression of hMLH1 protein below the limits of detection by Western blotting, DNA MMR activity remained fully functional (by direct DNA MMR activity assay). We would speculate that hMLH1 is expressed in substantially greater abundance than would be minimally necessary for DNA MMR and that minor reductions in the expression of this protein would not be sufficient to permit DNA MMR dysfunction. Alternatively, Chr3 may contain a second hMLH1 homologue that might overlap with the function of hMLH1.

Enterocyte growth and differentiation occur simultaneously within the epithelium, but little is known regarding any relationship between these two processes. Four rat models of small intestinal epithelial hypo- and hyperplasia (neonatal ontogeny, fasting/refeeding, hypo-/hyperthyroidism, and bombesin treatment) were used to study the regulation of enterocyte gene expression in relation to epithelial growth state. Mucosal scrapings, as well as crypt and villus cell populations, were subjected to Northern blot analyses using radiolabeled cDNA probes corresponding to lactase, intestinal alkaline phosphatase, villin, ornithine decarboxylase (ODC), and the actin control. In all four models, the hypoplastic (atrophic) condition is characterized by high levels of lactase and low levels of the 3.0-kb intestinal alkaline phosphatase mRNA, whereas under hyperplastic conditions this pattern is reversed. The changes in intestinal alkaline phosphatase and lactase are qualitatively similar along the longitudinal axis of the intestine and are proportional to the degree of hyperplasia, as verified by ODC mRNA levels. Furthermore, the crypt-villus axis of differentiation is maintained regardless of epithelial growth state. In conclusion, the pattern of brush-border enzyme gene expression changes as a function of epithelial growth state, indicating a previously unrecognized degree of plasticity to the state of enterocyte differentiation.