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COVID-19, caused by SARS-CoV-2 infection, has recently been announced as a pandemic all over the world. Plenty of diagnostic, preventive and therapeutic knowledges have been enriched from clinical studies since December 2019. However, animal models, particularly non-human primate models, are urgently needed for critical questions that could not be answered in clinical patients, evaluations of anti-viral drugs and vaccines. In this study, two families of non-human primates, Old world monkeys (12 Macaca mulatta, 6 Macaca fascicularis) and New world monkeys (6 Callithrix jacchus), were experimentally inoculated with SARS-CoV-2. Clinical signs were recorded. Samples were collected for analysis of viral shedding, viremia and histopathological examination. Increased body temperature was observed in 100% (12/12) M. mulatta, 33.3% (2/6) M. fascicularis and none (0/6) of C. jacchus post inoculation of SARS-CoV-2. All of M. mulatta and M. fascicularis showed chest radiographic abnormality. Viral genomes were detected in nasal swabs, throat swabs, anal swabs and blood from all 3 species of monkeys. Viral shedding from upper respiratory samples reached the peak between day 6 and day 8 post inoculation. From necropsied M. mulatta and M. fascicularis, the tissues showing virus positive were mainly lung, weasand, bronchus and spleen. No viral genome was seen in any of tissues from 2 necropsied C. jacchus. Severe gross lesions and histopathological changes were observed in lung, heart and stomach of SARS-CoV-2 infected animals. In summary, we have established a NHP model for COVID-19, which could be used to evaluate drugs and vaccines, and investigate viral pathogenesis. M. mulatta is the most susceptible to SARS-CoV-2 infection, followed by M. fascicularis and C. jacchus. One Sentence SummaryM. mulatta is the most susceptible to SARS-CoV-2 infection as compared to M. fascicularis and C. jacchus.
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Objective To investigate the CT and MRI features of solid-cystic papillary tumors(SCPTs) of the pancreas.Methods Eight cases of SCPTs confirmed by operation and pathology underwent both plain and contrast-enhanced CT examination,and MR examination in three cases and contrast-enhanced MRI in two cases.Results In the eight patients,the mean tumor diameter was 7.6 cm and the lesions were found mainly in the body and tail of the pancreas,only one at the pancreatic head.On plain CT scan,the tumors appeared as huge solid-cystic mass with definite margin and an integritied capsul,the solid areas were papillary or irregular components,and the cystic areas in central were low attenuation.On contrast-enhanced CT,the cystic wall and solid part were slight enhancement in arterial phase,and moderate or obvious enhancement in parenchymal phase.Irregular ringed and punctate calcification could be seen in five cases,the acute hemorrhage occurred in one case,slight dilation of the pancreatic duct was noticed in one patient.MRI showed an ovoid solid-cystic mass of the pancreas with distinct border.On T1WI,heterogeneous iso-and hypo-intensity was observed.One case showing the high signal intensity in tumor was subacute hemorrhage.On T2WI,the tumors were mixed hypo-,iso-and hyperintensity.The papillary or flocculent solid portion and the cystic wall were enhanced after gadolinium was used.Conclusion SCPTs is of certain clinic,CT and MRI characteristic findings,which can aid in reaching a proper diagnosis.
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Objective To evaluate the CT value in diagnosis and differential diagnosis of splenic tumors.Methods 52 cases of splenic tumors were examined by plain and contrast-enhanced CT scan.27 cases of splenic tumors were confirmed by operation and pathology,25 cases were definited by clinical history and having typical imaging signs.Results There were 18 benign and 34 malignant tumors.Most of benign splenic tumors appeared as single or multiple low dense nodus with different size,one hemangioma was isodense.Calcifications could be showed in splenic hemangioma and lymphangioma.Homogeneous and marked enhancement occurred in hemangiomas at delayed-phase,no or slightly enhanced in the septum of splenic lymphangiomas,and the cysts had no enhanced.The malignant tumors of spleen were bigger in size mostly with unhomogeneous density,and unhomogeneous enhancement could be seen at contrast-enhanced CT scan.Uneven enlargement of spleen was commonly seen in patients of splenic lymphoma and the lesions were multiple in a most of cases,and had not enhancement obviously.Conclusion Splenic tumors can be diagnosed correctly in most patients based on the features of plain and contrast-enhanced CT in combination with clinical history and the other examinations.
