Primary diffuse leptomeningeal glioneuronal tumors.

Diffuse leptomeningeal disseminated glioneuronal tumor (DL-GNT) is a rare brain tumor that presents as a plaque-like subarachnoid tumor, commonly involving the basal cisterns and interhemispheric fissure of children but lacking intraparenchymal tumor. Histologically, the tumors are composed of sheets of monotonous rounded cells. Here, we report three cases of DL-GNTs, focusing on clinicopathologic features. Two patients were adult male, but one patient was child. The patients presented with seizures (n = 1) or headaches (n = 2). In all patients, radiography revealed characteristic leptomeningeal thickening and enhancement with minor superficial parenchymal lesions. All three cases were diffusely positive for both GFAP and synaptophysin, and scattered positive for OLIG2 and NeuN, but negative for IDH-1 (H09). Electron microscopic examination showed astrocytic and neuronal differentiation. The patient with the anaplastic tumor died due to aggressive progression of the tumor, but the remaining two patients were stable without tumor recurrence for 23 and 37 months. Thus, these findings suggest that DL-GNT can occur in both children and adult and both supra- and infra-tentorial leptomeninges. It has unique radiological and histopathological features and biological behavior. Further clinicopathological data with molecular genetic study are required for establishing DL-GNT as a unique entity.

The effect of resin shades on microhardness, polymerization shrinkage, and color change of dental composite resins.

The present study sought to evaluate the effect of resin shades on the degree of the polymerization. To this end, response variables affected by the degree of polymerization were examined in this study - namely, microhardness, polymerization shrinkage, and color change. Two commercial composite resins of four different shades were employed in this study: shades A3, A3.5, B3, and C3 of Z250 (Z2) and shades A3, A3.5, B3, and B4 of Solitaire 2 (S2). After light curing, the reflectance/absorbance, microhardness, polymerization shrinkage, and color change of the specimens were measured. On reflectance and absorbance, Z2 and S2 showed similar distribution curves regardless of the resin shade, with shade A3.5 of Z2 and shade A3 of S2 exhibiting the lowest/highest distributions. Similarly for attenuation coefficient and microhardness, the lowest/highest values were exhibited by shade A3.5 of Z2 and shade A3 of S2. On polymerization shrinkage, no statistically significant differences were observed among the different shades of Z2. Similarly for color change, Z2 specimens exhibited only a slight (DeltaE*=0.5-0.9) color change after immersion in distilled water for 10 days, except for shades A3 and A3.5. Taken together, results of the present study suggested that the degree of polymerization of the tested composite resins was minimally affected by resin shade.

Prevalence and toxigenic profiles of Bacillus cereus isolated from dried red peppers, rice, and Sunsik in Korea.

Bacillus cereus is a spore-forming foodborne pathogen responsible for diarrheal and emetic types of food poisoning. Intoxication is caused by various enterotoxins or by emetic toxin. Because of its widespread presence and the ability to form heat-stable endospores in a relatively short time, B. cereus has been difficult to control. In this study, 21 rice and 36 Sunsik (a mixture of powdered raw grains) samples were examined for the prevalence of B. cereus. A multiplex PCR assay was used to evaluate the distribution of 10 different toxigenicity-related genes among 1,082 B. cereus strains isolated from dried red peppers (919 isolates), rice (98 isolates), and Sunsik (65 isolates). The results suggest that (i) the examined foods were free of the emetic toxin but not free of enterotoxins and (ii) the distribution of enterotoxigenic genes was significantly different among the B. cereus isolates from various sources.

Prevalence and genetic diversity of Enterobacter sakazakii in ingredients of infant foods.

Various food samples in Korea were examined for the presence of Enterobacter sakazakii. Dried shrimp had the highest contamination rate among the examined dried fish products. E. sakazakii isolates were confirmed using an API 20E kit and a polymerase chain reaction (PCR) targeting the rDNA operons. The isolates were subtyped by pulsed-field gel electrophoresis (PFGE) using XbaI to elucidate the genetic diversity of the organisms. Ten pulsotypes were identified using PFGE and 22 types were identified from the random amplified polymorphism DNA (RAPD) assay. An antibiotic resistance test was performed by disk diffusion assay using eight antibiotics: nalidixic acid, ciprofloxacin, chloramphenicol, ampicillin, tetracycline, gentamicin, kanamycin, and cephalothin. Most of the E. sakazakii isolates were resistant to ampicillin or cephalothin but susceptible to the other antibiotics. The analysis of E. sakazakii isolates using PFGE, RAPD, and the antibiotic resistance test identified 18 composite types from 113 isolates, suggesting diverse sources of contamination.

Changes in patterns of antimicrobial susceptibility and integron carriage among Shigella sonnei isolates from southwestern Korea during epidemic periods.

Shigella sonnei isolates from southwestern Korea during the epidemic periods of 1998 to 2000 were genetically related. The antimicrobial susceptibilities of the outbreak-related isolates changed annually. All isolates carried class 2 integrons, and the outbreak-related isolates from 1999 also carried class 1 integrons. The antimicrobial susceptibilities of S. sonnei isolates are readily changed by antibiotic selective pressures, and integrons are responsible for resistance to antimicrobial agents commonly used to treat shigellosis.