Antibiotics-associated pseudomembranous colitis is well documented and caused by abnormal overgrowth of toxin producing Clostridium difficile colonizing the large bowel of patients undergoing antibiotic therapy. Administration of chemotherapeutic agents is frequently complicated by diarrhea and enterocolitis. However, pseudomembranous colitis related to chemotherapeutic agent usage is very rare. We experienced a 67 old-years male patient diagnosed of non-small cell lung carcinoma who complained of watery diarrhea and abdominal pain after treated with paclitaxel and carboplatin. Sigmoidoscopic examination revealed diffusely scattered, whitish to yellowish pseudomembrane with background edematous hyperemic mucosa from sigmoid colon to rectum. Histopathologic findings were consistent with pseudomembranous colitis as typical volcano-like exudate. The symptoms improved after stopping chemotherapy and treatment with metronidazole. In patients with persistent diarrhea and abdominal pain after receiving chemotherapy agents, although rare, pseudomembranous colitis should be considered as a differential diagnosis.

Recently, a barium(Ba) and an iodine(I) being studied as a conventional lead(Pb) alternatives of shielding material has excellent shieding rate, but the characteristic x-ray photons in the energy range near 30 keV line is released. In this study, with bismuth oxide(BiO) coupled barium sulfate(BaSO 4 ) double layer, transmitted spectra, shieding rates and relative weighting rates were evaluated to validate the applicability of eco-friendly double layer shieding structure using monte carlo simulations as a prior study. From the evaluation results, in 0.4mm and 0.5mm thickness of BiO layers coupled with top 0.1mm-BaSO 4 layer, the shieding rate showed 1.9% and 3.9% higher than 0.6mm thickness of Pb single layer, respectively. In addition, the relative weight also 28% and 34.5% lower than 0.6mm-Pb in 0.4mm and 0.5mm thickness of BiO layers coupled with top 0.1mm-BaSO 4 layer.

Bacterial chitosanases share weak amino acid sequence similarities at certain regions of each enzyme. These regions have been assumed to be important for catalytic activities of the enzyme. To verify this assumption, the functional importance of the conserved region in a novel thermostable chitosanase (TCH-2) from Bacillus coagulans CK108 was investigated. Each of the conserved amino acid residues (Leu64, Glu80, Glu94, Asp98, and Gly108) was changed to aspartate and glutamine or asparagine and glutamate by site-directed mutagenesis, respectively. Kinetic parameters for colloidal chitosan hydrolysis were determined with wild-type and 10 mutant chitosanases. The Leu64 --> Arg and Leu64 --> Gln mutations were essentially inactive and kinetic parameters such as Vmax and kcat were approximately 1/10(7) of those of the wild-type enzyme. The Asp98 --> Asn mutation did not affect the Km value significantly, but decreased kcat to 15% of that of wild-type chitosanase. On the other hand, the Asp98 --> Glu mutation affected neither Km nor kcat. The observation that approximately 15% of activity remained after the substitution of Asp98 by Asn indicated that the carboxyl side chain of Asp98 is not absolutely required for catalytic activity. These results indicate that the Leu64 residue is directly involved in the catalytic activity of TCH-2.

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