Feasibility of using tissue autolysis to estimate the postmortem interval in horses

Estimation of the postmortem interval (PMI) is a poorly studied field in veterinary pathology. The development of field-applicable methods is needed given that animal cruelty investigations are increasing continually. We evaluated various histologic criteria in equine brain, liver, and muscle tissue to aid the estimation of PMI in horses, which is central to forensic investigations of suspicious death. After death, autolysis proceeds predictably, depending on environmental conditions. Currently, no field-applied methods exist that accurately estimate the PMI using histology in animals or humans through quantification of autolysis. Brain, liver, and skeletal muscle from 12 freshly euthanized horses were held at 22°C and 8°C for 72 h. Tissues were sampled at T0h, T1h, T2h, T4h, T6h, T12h, T24h, T36h, T48h, T60h, and T72h. For each tissue, we quantified 5 to 7 criteria associated with autolysis, based on the percentage of microscopic field involved. Each criterion was modeled, with temperature and time as independent variables. Changes were most predictable in liver and muscle over the first 72 h postmortem. The criteria for autolysis that were present most extensively at both temperatures were hepatocyte individualization and the separation of bile duct epithelium from the basement membrane. The changes that were present next most extensively were disruption of myofiber continuity, hypereosinophilia, and loss of striation. Brain changes were highly variable. The high statistical correlation between the parameter “autolysis” and the variables “time/temperature”, indicates that autolysis is progressive and predictable. Further investigation of these criteria is needed to establish histologic algorithms for PMI.

A redox probe screens MTHFD1 as a determinant of gemcitabine chemoresistance in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a type of solid tumor derived from the bile duct epithelium that features universal gemcitabine resistance. Here, we utilized a gene-encoded ROS biosensor probe (HyPer3 probe) to sort subpopulations with different redox statuses from CCA cells. The isolated HyPer-low subpopulation CCA cells, which exhibited relatively lower cellular ROS levels, exhibited higher chemoresistance to gemcitabine than HyPer-high subpopulation CCA cells in vitro and in vivo. Mechanistically, increased expression of MTHFD1 was found in HyPer-low cells. Knocking down MTHFD1 in HyPer-low cells enhanced cellular ROS and restored sensitivity to gemcitabine. Furthermore, the MTHFD1 inhibitor antifolate compound methotrexate (MTX) increased cellular ROS, and combining gemcitabine with MTX effectively suppressed cholangiocarcinoma cell growth. In summary, the MTHFD1 level mediated the heterogeneous cellular redox status in CCA, which resulted in chemoresistance to gemcitabine. Our data suggest a novel strategy for CCA chemotherapy.

Oesophageal squamous cell carcinoma mimicking submucosal tumour

Background Oesophageal submucosal tumours are usually benign. We report a rare case of esophageal squamous cell carcinoma presenting as a submucosal tumour. Case presentation A 58-year-old man undergoing screening oesophago-gastroduodenoscopy was found to have a smooth-surfaced 0.6-cm sized submucosal tumour in the oesophagus 30 cm from the incisor. Endoscopic ultrasonography showed the tumour to be located in the muscularis mucosa; the lesion was heterogeneously hypoechoic and had a clear boundary. With a provisional diagnosis of leiomyoma, the tumour was removed by endoscopic submucosal dissection. Pathological examination showed it to be a moderately differentiated infiltrating squamous cell carcinoma, with normal overlying squamous epithelium. Immunohistochemistry indicated that it was caused by malignant transformation in mucosal glandular duct epithelium. Positron emission tomography–computer tomography showed no tumour spread to any other site. The patient was treated by oesophageal resection. Conclusion The clinician should be aware that oesophageal submucosal tumours with smooth overlying mucosa may not always be benign; malignancy must be ruled out.

380. First Reports of Salivary Gland Involvement in Corona Virus Disease 2019

Background Many viruses infect salivary glands. These include mumps, Epstein-Barr, herpes virus 6, parainfluenza, influenza, adeno virus, boca virus and others. Almost all coronavirus disease 2019 (COVID -19) infected patients carry the virus in saliva. Salivary duct epithelium were the early target cells in macaque monkeys infected with severe acute respiratory syndrome corona virus (SARS-COV). Here we present 2 COVID-19 cases with the involvement of salivary glands. Salivary gland involvement has not been reported in COVID-19. Methods We followed the COVID 19 clinical findings in a Pennsylvania long term care facility with 190 residents. Thirty tested polymerase chain reaction (PCR) positive. However, 48 were presumed infected. Eighteen likely cases were not tested due to shortage of swabs. Thirty four employees also tested positive. Two out of 48 patients aged 78 and 88 developed unilateral sialadenitis during the course of the illness. Both were Hispanic females. We studied the Clinical presentations, co-morbidities, lab and imaging results and the outcome. Results Case 1: Two days after the first confirmed case, a 88 year old Hispanic female developed fever and fatigue and tested COVID-19 positive. Fever lasted 5 days. Twenty days later the patient developed a 5x3 cm tender left parotid mass and hypoxia treated with oxygen via nasal cannula. (Table 1) Case 2: A 78 year old Hispanic female developed high fever and cough 7 days after the index case. Six days later she had persistent fever and presented with a tender 8.5x3.5 cm right submandibular mass. The patient was intubated for 3 days to protect the airway due to the size of the mass. Both made an uneventful recovery. (Table 1 and Figure 1) Conclusion New clinical findings of COVID -19 have been gradually added during the course of the pandemic. The virus is almost universally present in the saliva. In experimental Chinese macaques with SARS-COV early target cells were the salivary duct epithelium. Salivary gland inflammation and swelling should be included amongst the clinical features of COVID-19. Disclosures All Authors: No reported disclosures

Drug-induced Bile Duct Injury - A Short Review

: The liver represents the major site of drug metabolism, i.e. the key organ in the processes of detoxification and elimination of drugs from the organism. It is therefore often affected by toxic metabolites and suffers sometimes fatal consequences. The spectrum of pathologies differs by the cell type primarily damaged and the group of the cholangiopathies includes those conditions affecting the bile duct epithelium or the cholangiocytes. They can range from transient cholestasis to vanishing bile duct syndrome and sclerosing cholangitis, both leading eventually to the development of biliary fibrosis and cirrhosis. : In this review article, we focus on the etiology, predisposing factors, clinical manifestations, and histopathological characteristics of bile duct injury as a consequence of drug treatment and discuss separately the different bile duct pathologies.