Morphological analysis of patchy thickening and reddish discoloration of active hair growth areas in the skin of New Zealand White rabbits.

Patchy thickening and reddish discoloration of active hair growth areas of skin in rabbits are occasionally found, and this gross feature could affect precise evaluation when conducting a dermal irritation test. Since little is known about the mechanism of this phenomenon, we examined the dorsal skin of New Zealand White rabbits morphologically and immunohistochemically in order to identify the possible mechanism responsible for developing these skin changes in relation to the hair cycle. Skin samples from 4 rabbits were divided into three groups (5 samples/group) based on their macroscopic characteristics: a thickened skin, erythematous skin, and smooth skin group. Histomorphological examination revealed that the percentage of hair follicles in the anagen phase, hair follicle length, hair follicle area, and proliferating cell nuclear antigen-positive cells in the hair follicles were greater in the thickened skin and erythematous skin groups than in the smooth skin group. Unlike mice and rats, the dermis was nearly adjacent to the muscular layer with a thin hypodermis, and the whole lengths of hair follicles in the anagen phase were located in the dermis in the rabbit skin. These results suggest that large hair follicles in the anagen phase compressed the surrounding dermis; therefore, the skin was grossly raised and showed thickening. A higher number of CD31-positive blood vessels, suggesting the occurrence of angiogenesis, was observed around the hair follicles in the erythematous skin group, and they seemed to affect the reddish discoloration of skin noted grossly.

Bacterial mutagenicity test data: collection by the task force of the Japan pharmaceutical manufacturers association.

BACKGROUND: Ames test is used worldwide for detecting the bacterial mutagenicity of chemicals. In silico analyses of bacterial mutagenicity have recently gained acceptance by regulatory agencies; however, current in silico models for prediction remain to be improved. The Japan Pharmaceutical Manufacturers Association (JPMA) organized a task force in 2017 in which eight Japanese pharmaceutical companies had participated. The purpose of this task force was to disclose a piece of pharmaceutical companies' proprietary Ames test data. RESULTS: Ames test data for 99 chemicals of various chemical classes were collected for disclosure in this study. These chemicals are related to the manufacturing process of pharmaceutical drugs, including reagents, synthetic intermediates, and drug substances. The structure-activity (mutagenicity) relationships are discussed in relation to structural alerts for each chemical class. In addition, in silico analyses of these chemicals were conducted using a knowledge-based model of Derek Nexus (Derek) and a statistics-based model (GT1_BMUT module) of CASE Ultra. To calculate the effectiveness of these models, 89 chemicals for Derek and 54 chemicals for CASE Ultra were selected; major exclusions were the salt form of four chemicals that were tested both in the salt and free forms for both models, and 35 chemicals called "known" positives or negatives for CASE Ultra. For Derek, the sensitivity, specificity, and accuracy were 65% (15/23), 71% (47/66), and 70% (62/89), respectively. The sensitivity, specificity, and accuracy were 50% (6/12), 60% (25/42), and 57% (31/54) for CASE Ultra, respectively. The ratio of overall disagreement between the CASE Ultra "known" positives/negatives and the actual test results was 11% (4/35). In this study, 19 out of 28 mutagens (68%) were detected with TA100 and/or TA98, and 9 out of 28 mutagens (32%) were detected with either TA1535, TA1537, WP2uvrA, or their combination. CONCLUSION: The Ames test data presented here will help avoid duplicated Ames testing in some cases, support duplicate testing in other cases, improve in silico models, and enhance our understanding of the mechanisms of mutagenesis.

Promoted cell proliferation by connexin 30 gene transfection to head-and-neck cancer cell line.

BACKGROUND: There have been inconsistent results regarding the contribution of the connexin family of genes to tumor cell proliferation. MATERIALS AND METHODS: We aimed to clarify the role of connexin 30 (Cx30), by transfecting three kinds of vectors that express either full length Cx30 (Cx30-Full), Cx30 devoid of C-terminal region (Cx30-DelC) or Cx30 C-terminal region (Cx30-CT), in HSC-4, a head-and-neck cancer cell line. RESULTS: Transfected Cx30-Full was localized on the plasma membrane, while Cx30-DelC and Cx30-CT was expressed in the cytoplasm or circumnuclear sites. We studied the effect on the growth rate followed by immunostaining with anti-Ki-67 (MIB-1). The MIB indices of HSC-4 cells transfected with Cx30-Full and Cx30-DelC, but not Cx30-CT were shown to be significantly higher than that of the controls. CONCLUSION: Our results demonstrated that Cx30 enhanced the proliferation of HSC-4 cells and the proliferating activity was considered to be achieved without the transport of the protein onto the plasma membrane.