RESUMO
The year 2021 has seen many breakthroughs in general internal medicine, despite the ongoing COVID-19 pandemic, with multiple implications in our daily clinical practice. From shorter antibiotic treatment duration in community-acquired pneumonia, to new indications for colchicine treatment, without forgetting better targets of hemoglobin for transfusion, questioning of the interest of high dose vitamin D substitution when preventing falls in older patients and finally disappointing hopes for new indications of albumin substitution in cirrhosis, the literature is full of new evidence. Each year, the chief residents of the internal medicine ward in Lausanne university hospital (CHUV) in Switzerland meet up to share their readings: here is a selection of ten articles, chosen, summarized, and commented for you.
L'année 2021, malgré la pandémie de Covid-19, a vu de nombreux progrès en médecine interne générale, avec de multiples implications pour notre pratique quotidienne. D'une durée diminuée d'antibiothérapie pour le traitement de la pneumonie communautaire à de nouvelles indications au traitement de colchicine, en passant par des précisions sur les cibles de transfusion érythrocytaire, ainsi qu'une remise en question de l'intérêt de la vitamine D à haute dose dans la prévention des chutes chez la personne âgée, et pour finir des espoirs déçus de nouvelle indication à la substitution d'albumine dans la cirrhose, les nouveautés abondent dans la littérature. Chaque année, les cheffes et chefs de clinique du Service de médecine interne du CHUV se réunissent pour partager leurs lectures : voici une sélection de dix articles choisis, revus et commentés pour vous.
Assuntos
COVID-19 , Pandemias , Idoso , Hospitais Universitários , Humanos , Medicina Interna , SARS-CoV-2RESUMO
BACKGROUND: Oleosin is a plant protein localized to lipid droplets and endoplasmic reticulum of plant cells. Our idea was to use it to target functional secretory proteins of interest to the cytosolic side of the endoplasmic reticulum of mammalian cells, through expressing oleosin-containing chimeras. We have designed this approach to create cellular models deficient in vitamin B12 (cobalamin) because of the known problematics associated to the obtainment of effective vitamin B12 deficient cell models. This was achieved by the overexpression of transcobalamin inside cells through anchoring to oleosin. METHODOLOGY: chimera gene constructs including transcobalamin-oleosin (TC-O), green fluorescent protein-transcobalamin-oleosin (GFP-TC-O) and oleosin-transcobalamin (O-TC) were inserted into pAcSG2 and pCDNA3 vectors for expression in sf9 insect cells, Caco2 (colon carcinoma), NIE-115 (mouse neuroblastoma), HEK (human embryonic kidney), COS-7 (Green Monkey SV40-transfected kidney fibroblasts) and CHO (Chinese hamster ovary cells). The subcellular localization, the changes in vitamin B12 binding activity and the metabolic consequences were investigated in both Caco2 and NIE-115 cells. PRINCIPAL FINDINGS: vitamin B12 binding was dramatically higher in TC-O than that in O-TC and wild type (WT). The expression of GFP-TC-O was observed in all cell lines and found to be co-localized with an ER-targeted red fluorescent protein and calreticulin of the endoplasmic reticulum in Caco2 and COS-7 cells. The overexpression of TC-O led to B12 deficiency, evidenced by impaired conversion of cyano-cobalamin to ado-cobalamin and methyl-cobalamin, decreased methionine synthase activity and reduced S-adenosyl methionine to S-adenosyl homocysteine ratio, as well as increases in homocysteine and methylmalonic acid concentration. CONCLUSIONS/SIGNIFICANCE: the heterologous expression of TC-O in mammalian cells can be used as an effective strategy for investigating the cellular consequences of vitamin B12 deficiency. More generally, expression of oleosin-anchored proteins could be an interesting tool in cell engineering for studying proteins of pharmacological interest.