Different Responses to 5-fluoraouracil in Mutagenicity and Gene Expression between Two Human Lymphoblastoid Cell Lines with or without TP53 Mutation

Human lymphoblastoid TK6 and WTK-1 cells are widely used to detect mutagens in vitro. TK6 cells have wild-type TP53 alleles, while WTK-1 cells have one allele of mutated TP53. Both cells were treated with 5-fluorouracil (5-FU), and gene mutation assay and micronucleus assay were performed to clarify the differential response related to the TP53 gene status. The effects of 5-FU on gene expression were assessed by microarray and quantitative RT-PCR analyses. In WTK-1 cells, 5-FU increased the frequency of cells with micronucleus and mutation. In TK6 cells, frequency of cells with micronucleus was increased but the mutation frequency was not. The cytotoxicity induced by 5-FU was more prominent in TK6 cells than in WTK-1 cells. Analysis of gene expression showed that the genes involved in the TP53 pathway were up-regulated in TK6 cells but not in WTK-1 cells. The differential responses to 5-FU between these cell lines appeared to be due to the difference in the TP53 gene status, thus providing a molecular basis for the bioassays using these cell lines in the toxicology field. Our results indicate that the clinical efficacy of 5-FU chemotherapy may depend on the TP53 genotype

An Attempt to Suppress the Induction of Contact Sensitivity to 2,4-Dinitrochlorobenzene by Tape Stripping Treatment of Guinea Pig Skin

The effect of stripping treatment with cellophane tape on induction of contact sensitivity (CS) to 2,4-dinitrochlorobenzene (DNCB) was studied in inbred JY1 strain guinea pigs in order to determine whether Langerhans cells (LC) are relevant to production of CS. Tape stripping of ear skin achieved, to a considerable degree but not absolutely, depletion of epidermal LC, as measured by cell surface of LC dedetcted by ATPase staining. However, pretreatment of tape stripping on the induction site of contact sensitization with DNCB did not diminish the rate and intensity of challenge reactions to DNCB

Changes in Epidermal Langerhans Cells Following the Tuberculin Reaction in Guinea Pigs

Changes in Langerhans cells (LCs) with the tuberculin reaction were studied using EDTA (ethylenediaminetetraacetic acid) separation and ATPase (adenosine triphosphatase) staining techniques in guinea pig epidermis following intradermal PPD injections. The densities of ATPase positive LCs decreased significantly (p<0.001) from 24 hours to 7 days after injection with a maximum decrease at 72 hours. In addition, these cells became rather swollen or enlarged and lost their characteristic dendritic processes. The significance of these changes is discussed

Nevus Comedonicus on the Right Cheek

Case report of a 22-year- old lady with comedo-like lesion of the right cheek is presented here. The lesion was removed surgically and diagnosed nevus comedonicus by histopathological study. Localized nevus comedonicus of the cheek is rare and not many cases have been reported

Perchloric acid-soluble protein regulates cell proliferation and differentiation in the spinal cord of chick embryos

AbstractThe role of perchloric acid-soluble protein (PSP) was investigated in chick embryos. Fluorescently labeled anti-chick liver (CL)-PSP IgG was injected into the yolk sac in ovo at embryonic day 3, and became localized in neuroepithelial cells. Within 12h, morphological changes were observed in 37.5% of anti-CL-PSP IgG-injected embryos, and the neuroepithelial cells formed a wavy line. No significant changes were observed in embryos injected with non-immune IgG or PBS. Increased expression of PCNA and decreased expression of neuronal class III β-tubulin were observed in the spinal cord after anti-CL-PSP IgG injection. These results suggest that PSP controls the proliferation and differentiation of neuroepithelial cells in chick embryos