Browsing by Author "Choo, Vincent"
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Item Histological and Immunohistochemical Findings in Two Subtypes of Hepatitis B Related Acute Liver Failure(2017-01-17) Choo, Vincent; Peng, Lan; Dao, Doan Y.; Hameed, Bilal; Lee, William M.; Acute Liver Failure Study Group (ALFSG)BACKGROUND: Acute liver failure (ALF) occurs when rapid-onset, severe liver cell damage results in coagulopathy and encephalopathy. Multiple etiologies yield a remarkably similar syndrome including acetaminophen overdose, drug-induced liver injury, and Hepatitis B Virus (HBV) infection. ALF in the setting of HBV occurs in 1% of primary acute HBV infections (AHBV-ALF), but can also evolve during chronic HBV infection (CHBV-ALF), particularly in reactivation, when patients receive immunosuppressive or cancer chemotherapy. OBJECTIVE: To determine whether differences between the two varieties of HBV-ALF, primary acute HBV infection and reactivation of HBV, are reflected in differences in HBV immunohistochemical bio-markers in liver: HBV core antigen (HBcAg) & HBV surface antigen (HBsAg). METHODS: A total of 21 patients from the Acute Liver Failure Study Group (ALFSG) were identified as having sufficient liver tissue for the staining panel required. Samples were immunostained using dye-labeled antibodies for HBV core antigen (HBcAg) and HBV surface antigen (HBsAg). We performed routine hematoxylin & eosin (H&E) staining for overall morphology (degree of necrosis, presence of plasma cells) and reviewed clinical history to stratify each case as either AHBV-ALF (primary infection, N=11) or CHBV-ALF (reactivation, N=10). For H&E, we assessed number of plasma cells, percent tissue necrosis, and degree of collapse. Eleven biopsies had <25% viable hepatocytes, making further analysis of staining patterns unsuccessful. The remaining acute HBV cases had very little, if any, HBsAg staining and variable levels of nuclear HBcAg staining. In contrast, one CHBV-ALF case had intense staining for both HBsAg and HBcAg, probably related to the presence of immunosuppression. SUMMARY/CONCLUSION: Immunohistochemical staining of liver biopsies/explants revealed scant viable hepatocytes in more than half, limiting assessment of location of viral products within cells. In general, when assessment was possible, AHBV-ALF demonstrated little to no HBsAg and variable amounts of HBcAg staining. Immunosuppression leads to much higher levels of HBV proteins within hepatocytes, and perhaps suggests that the virus is directly cytotoxic in this setting. By the time of liver transplantation, virtually all HBsAg had disappeared from hepatocytes in AHBV-ALF, but high quantities of HBsAg and HBcAg were found in immunosuppressed patients with reactivation. These two forms of acute liver failure due to hepatitis B have remarkably different pathogenetic phenotypes.Item The State of Anesthesia Practice in Sub-Saharan Africa: Statistics, Case Studies, and Ways Forward(2020-03-12) Choo, Vincent; Mihalic, Angela; Ambardekar, Aditee; Tao, WeikeBACKGROUND: There is substantial need for additional anesthesia resources in Sub-Saharan Africa. In this region of the world, maternal and surgical mortality are high. Non-coincidentally, the number of anesthesiologists and anesthesia providers is low and provision of medications and other basic supplies is lacking. This thesis aims to describe anesthesia practice in Sub-Saharan Africa using statistics and case studies, present current initiatives already in place to improve access to care, and suggest other strategies that may improve anesthesia capacity in the future. OBJECTIVE: Non-adherence to minimum guidelines from the World Federation of Societies of Anaesthesiologists (WFSA) for anesthesia practice in the areas of staffing and physical resources is associated with poor anesthesia and surgical outcomes, which could be improved by improving training programs and increasing available physical resources. METHODS: A Pubmed literature search was performed using key words. Relevant articles from these searches were retrieved and references from these articles were also examined. Websites for organizations mentioned in the articles were queried. Websites containing factual information about individual Sub-Saharan African countries were consulted. The information found was grouped by themes and presented. RESULTS: The numbers of anesthesiology providers in Sub-Saharan Africa are insufficient to provide safe anesthesia care. A lack of medications and supplies and inadequate technology, including monitoring equipment, contribute to the problem. The situation in Ghana, Mozambique, Liberia, and Rwanda helps to illustrate this problem. Initiatives such as the founding of the World Federation of Societies of Anaesthesiologists and Lifebox, as well as formalizing task-sharing, have attempted to improve the situation. Continuing to ensure that equipment adapted to the reality of the practice environment in the region and careful planning and coordinating of future humanitarian projects can help improve anesthesia care provided in the region. CONCLUSION: The current state of anesthesia in Sub-Saharan Africa is insufficient to meet population needs. The causes are multi-factorial and include issues providing adequate human and material resources. Establishing strong, coordinated humanitarian efforts on the ground is critical to addressing the problem. Reorganizing manpower to best utilize precious human resources is another way forward. Providing appropriate resources in the form of equipment and medications, as well as encouraging local research, can help provide innovative solutions for the region.