The utility of video capsule endoscopy (VCE) for the detection of small bowel bleeding arising from benign and malignant tumors: report of two cases.

Video capsule endoscopy (VCE) has become a first-line diagnostic tool for the diagnosis of small bowel bleeding. Prior to VCE, procedures to visualize the site of small intestinal bleeding were rudimentary and frequently delivered inconclusive findings. VCE allows for improved visualization, resulting in more accurate identification of benign and malignant tumors of the small bowel. VCE provides the opportunity for prompt identification while allowing for precise surgical excision of the involved bowel, with maximum salvage of normal tissue. We report two clinical cases of small bowel tumors diagnosed by using video capsule endoscopy. The pathology showed one lesion to be a lipoma and the other a carcinoid tumor. Both cases presented in similar fashions as intestinal hemorrhage, yet one lesion was benign and the other malignant.

Effect of transannular interaction on the redox-potentials in a series of bicyclic quinones.

BACKGROUND: Better understanding of the transannular influence of a substituent on the redox-potentials of bicyclo[2.2.2]octane-derived quinones will help in the design of new compounds with controlled biological activity. However, attempts to directly relate the reduction potentials of substituted triptycene-quinones to the electronic effects of substituents are often unsuccessful. RESULTS: First and second redox-potentials of a series of bicyclic quinones are compared to computed energies of their LUMO, LUMO+1, and energies of reduction. Transannular influence of substituent on the redox-potentials is rationalized in terms of MO theory. Acetoxy-substituents in the 5,8-positions of the triptycene-quinone system selectively destabilize the product of the two-electron reduction. CONCLUSION: We have shown that first redox-potentials of substituted bicyclic quinones correlate with their calculated LUMO energies and the energies of reduction. The second redox-potentials correlate with calculated LUMO+1 energies. As opposed to the LUMO orbitals, the LUMO+1 orbital coefficients are weighted significantly on the non-quinone part of the bicyclic system. This accounts for: (1) significantly larger substituent effect on the second redox-potentials, than on the first redox-potentials; (2) lack of stability of the product of two electron reduction of 5,8-diacetoxy-9,10-dihydro-9,10-[1,2]benzenoanthracene-1,4-dione 5.