Journal of Toxicologic Pathology最新文献

Laser resurfacing may be accompanied by unwanted side effects. The micro coring technology, designed to remove small skin columns, was developed to avoid the thermal injury associated with lasers. However, very limited data are available on its pre-clinical efficacy and safety. The novel robotic, fractional micro-coring device, Aime^TM, was tested on four pigs, each treated in 12 sites, at 6 time-points, over the course of 28 days. Macroscopic and microscopic evaluation was performed at each of the 6 time-points during the 28-day follow-up. Macroscopically, treatment resulted in erythema and mild edema that quickly resolved. Microscopically, there was progressive re-coverage of the tested sites with complete, well differentiated, newly formed epidermis, associated with efficient elimination of the underlying excised dermis, which was replaced by maturing fibroplasia. Some of the sites demonstrated complete healing already after 7 days. No significant adverse events were noted with the use of the device. The use of the micro-coring device Aime^TM in a porcine model for skin fractional micro-excision and resurfacing was effective and safe. The comprehensive gradual healing process shown in this study with detailed histopathological images can also serve as a basis for future pre-clinical studies of fractional ablative devices.

Spontaneous cartilaginous metaplasia of the sclera has not been reported in rabbits. Herein, we report two cases of spontaneous cartilaginous metaplasia in the sclera of Japanese White (JW) rabbits. Case 1 was noted in a 14-week-old male Kbs:JW rabbit that received a single ocular instillation of 20% isoproterenol (IP) a day before necropsy, and showed no abnormalities in clinical signs, ophthalmological assessments, and necropsy. Case 2 was noted in a 38-week-old male Kbs:JW rabbit that was housed under light-emitting diode (LED) lighting for 26 weeks and showed no effects of LED on clinical signs, ophthalmological assessments, and necropsy. Histological sections of the eyes of both animals were prepared and stained with hematoxylin and eosin (H&E) and Alcian blue, and immunohistochemical staining for vimentin was performed. The H&E-stained specimens showed focal hyaline cartilage-like tissues distributed between the scleral fibers at the posterior pole in both cases. The surrounding scleral fibers were compressed and/or partially destroyed by the cartilage-like tissue. The cartilage-like matrix was stained blue by Alcian blue, and immunohistochemistry showed that chondrocyte-like cells were positive for vimentin. Based on these findings, we diagnosed cartilaginous metaplasia in the sclera of Kbs:JW rabbits. The lesion was farther from the IP administration site in Case 1 and was not accompanied by other ophthalmological or histopathological abnormalities in either of the cases. This implies that the lesions occurred spontaneously owing to the abnormal differentiation of neural crest-derived cells.

Recently, with the development of computer vision using artificial intelligence (AI), clinical research on diagnosis and prediction using medical image data has increased. In this study, we applied AI methods to analyze hepatic fibrosis in mice to determine whether an AI algorithm can be used to analyze lesions. Whole slide image (WSI) Sirius Red staining was used to examine hepatic fibrosis. The Xception network, an AI algorithm, was used to train normal and fibrotic lesion identification. We compared the results from two analyses, that is, pathologists' grades and researchers' annotations, to observe whether the automated algorithm can support toxicological pathologists efficiently as a new apparatus. The accuracies of the trained model computed from the training and validation datasets were greater than 99%, and that obtained by testing the model was 100%. In the comparison between analyses, all analyses showed significant differences in the results for each group. Furthermore, both normalized fibrosis grades inferred from the trained model annotated the fibrosis area, and the grades assigned by the pathologists showed significant correlations. Notably, the deep learning algorithm derived the highest correlation with the pathologists' average grade. Owing to the correlation outcomes, we conclude that the trained model might produce results comparable to those of the pathologists' grading of the Sirius Red-stained WSI fibrosis. This study illustrates that the deep learning algorithm can potentially be used for analyzing fibrotic lesions in combination with Sirius Red-stained WSIs as a second opinion tool in non-clinical research.

In a 26-week carcinogenicity study in rasH2-Tg mice, squamous cell carcinoma on the epididymis was observed in a male mouse in the positive control group treated with N-methyl-N-nitrosourea. A 29-week-old male rasH2-Tg mouse that was euthanized 21 weeks after the administration of N-methyl-N-nitrosourea had a white-grayish mass on the left caput epididymis. The mass was nodular and consisted of pleomorphic tumor cells forming alveolar, sheeted, and trabecular structures suggesting epithelial tumor growth. These cells presented a cobblestone-like arrangement and formed intercellular bridges. Keratinization was infrequently observed. Periodic acid-methenamine-silver staining revealed argyrophilic fibrous structures around the alveolar structure of the tumor cells. Immunohistochemically, the tumor cells were positive for cytokeratin AE1/AE3 and cytokeratin 14 and negative for cytokeratin 5, p63, uroplakin III, vimentin, desmin, and αSMA. These immunohistochemical results suggested the tumor cells originated from the epididymal ducts. Metastatic lesions were observed in the mesenteric, inguinal, and pancreaticoduodenal lymph nodes. Based on these results, this tumor was diagnosed to be a primary squamous cell carcinoma of the epididymis. This is the first report of primary squamous cell carcinoma of the epididymis in a rasH2-Tg mouse.

5-Fluorouracil (5-FU) is widely used as a chemotherapeutic agent that blocks DNA synthesis and replication by inhibiting thymidylate synthetase. This study aimed to elucidate 5-FU-induced changes in the external granular cells (EGCs) in the cerebellum of infant rats and the possible underlying mechanism. Six-day-old infant rats were injected subcutaneously with 40 mg/kg of 5-FU, and their cerebellums were examined at 6, 9, 12, and 24 h after treatment (HAT), and 2, 4, and 10 d after treatment (DAT). The width of the external granular layer (EGL) decreased from 24 HAT to 4 DAT in the 5-FU group compared to that in the control group. However, the width in the 5-FU group was comparable to that of the control group at 10 DAT. The number of apoptotic cells, cleaved caspase 3-labeling index (LI%), p21^cip1-LI%, and expression levels of p53, p21^cip1, and Fas mRNAs increased at 24 HAT. However, no changes were detected in the expression levels of Puma and Bax mRNAs at any time point. BrdU-LI% increased at 6 and 12 HAT but decreased at 24 HAT. The phospho-histone H3-LI% decreased from 6 HAT to 2 DAT. The width of the molecular layer decreased compared to that of the control group at 10 DAT. No differences were observed in Purkinje cell development. These results indicate that 5-FU inhibited cell proliferation by inducing apoptosis of EGCs via activation of Fas and caspase-3 without the involvement of the mitochondrial pathway and induced p53-dependent G1-S and G2-M phase arrest.

Organoids derived from renal tissue stem cells (KS cells) isolated from the S3 segment of adult rat nephrons have previously been developed and evaluated. However, data regarding the histopathological evaluation of these organoids are limited. Therefore, in this study, we performed histopathological examinations of the properties of these organoids and evaluated the nephrotoxicity changes induced by cisplatin treatment. We observe that the tubular structure of the organoids was generally lined by a single layer of cells, in concordance with previous findings. Microvilli were exclusively observed under electron microscopy on the luminal side of this tubular structure. Moreover, the luminal side of the tubular structure was positive for aquaporin-1 (Aqp1), a marker of the proximal renal tubule. Cisplatin treatment induced cell death and degeneration, including cytoplasmic vacuolation, in cells within the tubular structure of the organoids. Cisplatin toxicity is associated with the induction of γ-H2AX (a marker of DNA damage) and the drop of phospho-histone H3 (a marker of cell division) levels. During the nephrotoxicity assessment, the kidney organoids displayed various features similar to those of the natural kidney, suggesting that it is possible to use these organoids in predicting nephrotoxicity. The histological evaluation of the organoids in this study provides insights into the mechanisms underlying nephrotoxicity.

To develop safe subcutaneous formulations and minimize the risk of local irritation, it is essential to optimize the composition of active pharmaceutical ingredients and excipients. Depending on the physicochemical properties of the active pharmaceutical ingredient, additional excipients may be required to improve the stability and solubility of the active pharmaceutical ingredient. However, some of these excipients may not have been previously used in injectable drugs. Owing to the lack of safety data for such excipients, especially those used in subcutaneous dosing, it is important to evaluate their potential for local irritation during the early stages of formulation development. We evaluated the tolerability of 44 formulations with 24 candidate novel excipients, such as surfactants, polymers, and lipids, in a single subcutaneous dose in rats. Excipient formulations were administered as single bolus subcutaneous injections with an injection volume of 1 mL. The injection sites were observed for 2 days, and macroscopic and microscopic examinations were conducted. Local tolerability was evaluated on the basis of severity, incidence, and pathophysiology of each finding. Formulations that caused tissue degeneration or necrosis, which is indicative of tissue injury, were determined to be irritative and poorly tolerated. A single-dose subcutaneous screening study in rats was considered effective in ranking the safety of candidate excipients during the formulation optimization phase.