The aim of this study was to evaluate the protective or deleterious effects of endogenous nitric oxide (NO) on liver cells during hepatic ischemia-reperfusion (IR) in the rat.
The analytical performance of hs-cTnT complied with the international guidelines for AMI detection. Determining the degree of haemolysis in a sample is of paramount importance to the interpretation of hs-cTnT results. The 99th percentile value of our reference population was established.
Splanchnic sequestration of amino acids (SSAA) is a process observed during aging that leads to decreased peripheral amino acid (AA) availability. The mechanisms underlying SSAA remain unknown. The aim of the present study was to determine whether a high-protein diet could increase nitrogen retention in aged rats by saturating SSAA and whether SSAA could be explained by dysregulation of hepatic nitrogen metabolism. Adult and aged male Sprague-Dawley rats were housed in individual metabolic cages and fed a normal-protein (17% protein) or high-protein diet (27%) for 2 wk. Nitrogen balance (NB) was calculated daily. On day 14, livers were isolated and perfused for 90 min to study AA and urea fluxes. NB was lower in aged rats fed a normal-protein diet than in adults, but a high-protein diet restored NB to adult levels. Isolated perfused livers from aged rats showed decreased urea production and arginine uptake, together with a release of alanine (vs. uptake in adult rats) and a hepatic accumulation of alanine. The in vivo data suggest that SSAA is a saturable process that responds to an increase in dietary protein content. The hepatic metabolism of AA in aged rats is greatly modified, and urea production decreases. This result refutes the hypothesis that SSAA is associated with an increase in AA disposal via urea production.
BackgroundThe quantification of cerebrospinal fluid (CSF) biomarkers (Amyloid beta peptides [Aß1‐40 and Aß1‐42], t‐tau and p‐tau(181)) is progressively implemented in specialized laboratories as an aid for the multidisciplinary diagnosis of Alzheimer’s disease (AD). There is however a diversity of practices between centers related to pre‐analytical and analytical conditions, the calculation of ratios between analytes, the applied cut‐off, or the use of interpretation scales. Finally, for the same biochemical profile, the interpretation and reporting of results may differ from one center to another, which may raise questions about the commutability of the tests. So far, no consensus has been reached between the different laboratories involved to define the most appropriate conclusions/comments based on the profile of the quantified biomarkers.This work is an essential step towards a consensual harmonization of clinical reporting after CSF analysis in the context of AD diagnosis, as advocated by the "Biofluid Based Biomarkers PIA" working group of the Alzheimer's Association.MethodWe obtained, by means of a questionnaire, a description of the pre‐analytical and analytical protocols and examples of reporting from 40 centers located in 15 countries, i.e. in the majority of countries that have implemented clinical CSF tests for the diagnosis of AD. We then adopted a consensus approach to propose harmonized comments corresponding to different AD CSF biomarker profiles observed in patients.ResultPre‐analytical procedures were very similar, among the centers. Regarding the analytical part, more than 88% of the laboratories use automatized immunoassays and more than 83% measure Aß1‐40 and compute the Aß1‐42/Aß1‐40 ratio, in addition to the three core biomarkers (Aß1‐42, t‐tau and p‐tau(181)). The cut‐off values of biomarkers used by the different laboratories are widely dispersed. Delay before sending back the results is lower than 1 week in more than 34% of the laboratories.ConclusionOur results highlight the state of the art in terms of clinical CSF analysis in the context of AD. Harmonization of clinical reporting between different centers could benefit AD care, prevention and treatment strategies, as a common terminology will allow a better assessment of the prevalence of AD and the contribution of biochemical biomarkers to its diagnosis.
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