Understanding yellow fever-associated myocardial injury: an autopsy study.

BACKGROUND: Yellow fever (YF) is a viral hemorrhagic fever, endemic in parts of South America and Africa. There is scarce evidence about the pathogenesis of the myocardial injury. The objective of this study is to evaluate the cardiac pathology in fatal cases of YF. METHODS: This retrospective autopsy study included cases from the São Paulo (Brazil) epidemic of 2017-2019. We reviewed medical records and performed cardiac tissue histopathological evaluation, electron microscopy, immunohistochemical assays, RT-qPCR for YF virus (YFV)-RNA, and proteomics analysis on inflammatory and endothelial biomarkers. FINDINGS: Seventy-three confirmed YF cases with a median age of 48 (34-60) years were included. We observed myocardial fibrosis in 68 (93.2%) patients; cardiomyocyte hypertrophy in 68 (93.2%); endothelial alterations in 67 (91.8%); fiber necrosis in 50 (68.5%); viral myocarditis in 9 (12.3%); and secondary myocarditis in 5 (6.8%). Four out of five patients with 17DD vaccine-associated viscerotropic disease presented with myocarditis. The cardiac conduction system showed edema, hemorrhages and endothelial fibrinoid necrosis. Immunohistochemistry detected CD68-positive inflammatory interstitial cells and YFV antigens in endothelial and inflammatory cells. YFV-RNA was detected positive in 95.7% of the cardiac samples. The proteomics analysis demonstrated that YF patients had higher levels of multiple inflammatory and endothelial biomarkers in comparison to cardiovascular controls, and higher levels of interferon gamma-induced protein 10 (IP-10) in comparison to sepsis (p = 0.01) and cardiovascular controls (p < 0.001) in Dunn test. INTERPRETATION: Myocardial injury is frequent in severe YF, due to multifactorial mechanisms, including direct YFV-mediated damage, endothelial cell injury, and inflammatory response, with a possible prominent role for IP-10. FUNDING: This study was funded by Fundação de Amparo à Pesquisa do Estado de São Paulo, Bill and Melinda Gates Foundation, Conselho Nacional de Desenvolvimento Científico e Tecnológico, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior.

Evaluation of Histological Properties of Human Meniscal Grafts Stored in a Tissue Bank.

Objectives The present paper aims to evaluate and compare the histological features of fresh and frozen menisci stored in a tissue bank for 1 month and for 5 years. Methods The meniscal grafts were subjected to a histological study. A total of 10 menisci were evaluated; 2 were frozen for 5 years, 4 were frozen for 1 month, and 4 were fresh, recently harvested specimens. Histological properties were evaluated in sections stained with hematoxylin and eosin and Masson trichrome methods. Results The menisci frozen for 1 month showed partially preserved collagen fiber structure and no significant hydropic tissue degeneration. The menisci frozen for 5 years presented an evident dissociation of collagen fibers and multiple foci of hydropic degeneration. Discussion Degeneration was much more significant in menisci stored for 5 years, indicating that a long freezing period results in substantial progression of tissue deterioration. This may suggest that the 5-year period, considered the maximum time for graft storage before transplant, is too long. Conclusion Grafts stored for 1 month showed a slight degenerative change in collagen fibers, whereas menisci frozen for 5 years presented significant tissue degeneration.

Evaluation of Histological Properties of Human Meniscal Grafts Stored in a Tissue Bank / Avaliação das propriedades histológicas de enxertos meniscais humanos armazenados em banco de tecido

Abstract Objectives The present paper aims to evaluate and compare the histological features of fresh and frozen menisci stored in a tissue bank for 1 month and for 5 years. Methods The meniscal grafts were subjected to a histological study. A total of 10 menisci were evaluated; 2 were frozen for 5 years, 4 were frozen for 1 month, and 4 were fresh, recently harvested specimens. Histological properties were evaluated in sections stained with hematoxylin and eosin and Masson trichrome methods. Results The menisci frozen for 1 month showed partially preserved collagen fiber structure and no significant hydropic tissue degeneration. The menisci frozen for 5 years presented an evident dissociation of collagen fibers and multiple foci of hydropic degeneration. Discussion Degeneration was much more significant in menisci stored for 5 years, indicating that a long freezing period results in substantial progression of tissue deterioration. This may suggest that the 5-year period, considered the maximum time for graft storage before transplant, is too long. Conclusion Grafts stored for 1 month showed a slight degenerative change in collagen fibers, whereas menisci frozen for 5 years presented significant tissue degeneration.

Resumo Objetivos Avaliar e comparar as características histológicas de meniscos frescos e meniscos congelados armazenados em banco de tecidos por 1 mês e por 5 anos. Métodos Foi feito um estudo histológico com enxertos meniscais. Avaliamos 10 meniscos, sendo 2 que ficaram armazenados sob congelamento por 5 anos, 4 armazenados congelados por 1 mês, e 4 frescos, recém captados. Foram feitos cortes histológicos corados com hematoxilina e eosina e Tricrômico de Masson, para avaliação das propriedades histológicas. Resultados Os meniscos congelados por 1 mês apresentaram preservação parcial da estrutura das fibras colágenas, sem degeneração hidrópica significativa do tecido. Nos meniscos congelados por 5 anos, observamos dissociação evidente das fibras colágenas, com presença de múltiplos focos de degeneração hidrópica. Discussão Encontramos degeneração bem mais significativa nos meniscos armazenados por 5 anos, o que indica que o longo período de congelamento leva à progressão significativa da degeneração do tecido. Isto pode sugerir que o período de 5 anos, considerado período máximo que o enxerto pode permanecer armazenado antes de ser transplantado, é um período muito longo. Conclusão Nos enxertos armazenados por 1 mês, existiu apenas discreta alteração degenerativa das fibras colágenas, enquanto que nos meniscos com 5 anos de congelamento foi observada degeneração significativa do tecido. Tibiais