This study examines the utility of four indices for use in model selection with nested and nonnested polytomous item response theory (IRT) models: a cross-validation index and three information-based indices. Four commonly used polytomous IRT models are considered: the graded response model, the generalized partial credit model, the partial credit model, and the rating scale model. In a simulation study, comparisons among the four indices suggest that model selection is dependent to some extent on the particular conditions simulated. Overall, the Bayesian information criterion index appears to be most accurate in selecting the correct polytomous IRT model. Results are presented from analysis of a real data set to illustrate the use of the four indices for selecting an appropriate model.

Background: It is important to differentiate between schwannomas and neurofibromas for the cases in which the histopathologic features overlap. Depending on the tumor type, surgeons can decide on a treatment method and whether to preserve or sacrifice the nerve; the possibility of malignant transformation in the case of neurofibromas also needs to be considered. Methods:We studied 101 cases of schwannoma and 103 cases of neurofibroma. All the hematoxylin and eosin slides for these cases were reviewed, and tissue microarrays were prepared from the representative areas. Immunohistochemical analysis was performed using antibodies for S-100 protein, calretinin, CD56 and CD34. Results: All the tumors except 3 neurofibromas were positive for the S-100 protein. Calretinin was found in 26.7% of the schwannomas (27/101), but it was not found in any of the neurofibromas. CD56 was positive in 77.2% of the schwannomas (78/101) and in 9.8% of the neurofibromas (10/102). CD34 was positive in 42.5% of the schwannomas (43/101) and in 80.2% of the neurofibromas (81/101). Statistically, calretinin was significantly specific for schwannomas (p< 0.001) and CD56 was also sensitive for these tumors (p < 0.001). On the other hand, a CD34 expression seemed highly sensitive (p < 0.001) for neurofibromas. Conclusions: We concluded that combined immunohistochemical analysis for calretinin, CD56, and CD34 may be very useful for differentiating schwannomas from neurofibromas.

Cholangiopathy is a chronic immune-mediated disease of the liver, which is characterized by cholangitis, ductular reaction and biliary-type hepatic fibrosis. There is no proven medical therapy that changes the course of the disease. In previous studies, melittin was known for attenuation of hepatic injury, inflammation and hepatic fibrosis. This study investigated whether melittin provides inhibition on cholangitis and biliary fibrosis in vivo. Feeding 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) to mice is a well-established animal model to study cholangitis and biliary fibrosis. To investigate the effects of melittin on cholangiopathy, mice were fed with a 0.1% DDC-containing diet with or without melittin treatment for four weeks. Liver morphology, serum markers of liver injury, cholestasis markers for inflammation of liver, the degree of ductular reaction and the degree of liver fibrosis were compared between with or without melittin treatment DDC-fed mice. DDC feeding led to increased serum markers of hepatic injury, ductular reaction, induction of pro-inflammatory cytokines and biliary fibrosis. Interestingly, melittin treatment attenuated hepatic function markers, ductular reaction, the reactive phenotype of cholangiocytes and cholangitis and biliary fibrosis. Our data suggest that melittin treatment can be protective against chronic cholestatic disease in DDC-fed mice. Further studies on the anti-inflammatory capacity of melittin are warranted for targeted therapy in cholangiopathy.

Nongestational choriocarcinoma differentiation is extremely rare in breast neoplasms. It is characterized by tumor cells similar to chorionic trophoblastic cells, which react with human placental lactogen and human chorionic gonadotropin (hCG). A 56-year-old woman presented with a palpable right breast mass without past history of trophoblastic tumors. An F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) scan revealed one focus with low accumulation of FDG in the right breast (maximum standardized uptake value, 1.98). The patient underwent a right mastectomy and biopsy of sentinel nodes. Microscopically, the tumor was a typical invasive ductal carcinoma with multiple foci of choriocarcinoma features. Immunohistochemistry showed that the tumor cells resembling choriocarcinoma were positive for hCG antibody, but negative for HER2/neu, estrogen receptor, and progesterone receptor. A pathologic diagnosis of breast carcinoma with choriocarcinomatous features was made. To our knowledge, this is the first report of invasive carcinoma with choriocarcinomatous features and an unusual finding of low accumulation in an F-18 FDG PET/CT scan in Korea.

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Mucormycosis is a fungal infection that primarily causes opportunistic infections. Gastrointestinal mucormycosis is a rare infection that can occur in immunocompromised patients, nevertheless, prompt diagnosis and treatment is essential because it can be fatal. Gastrointestinal mucormycosis can only be diagnosed based on the findings of a pathological examination. Mucormycosis should be included in the differential diagnosis if the condition of patients with underlying immunocompromised conditions or diseases does not improve with general intensive care.

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