Allelic polymorphism of the apolipoprotein E (ApoE) gene (ApoE 2, ApoE 3 and ApoE 4 alleles) gives rise to three protein isoforms (ApoE2, ApoE3 and ApoE4) that differ by 1 or 2 amino acids. Inheritance of the ApoE 4 allele is a risk factor for developing Alzheimer's disease (AD). The potential diagnostic value of ApoE protein levels in biological fluids (i.e. cerebrospinal fluid, plasma and serum) for distinguishing between AD patients and healthy elderly subjects is subject to great controversy. Although a recent study reported subnormal total ApoE and ApoE4 levels in the plasma of AD patients, other studies have found normal or even elevated protein levels (versus controls). Because all previously reported assays were based on immunoenzymatic techniques, we decided to develop an orthogonal assay based on targeted mass spectrometry by tracking (i) a proteotypic peptide common to all ApoE isoforms and (ii) a peptide that is specific for the 4 allele. After trypsin digestion, the ApoE4-specific peptide contains an oxidation-prone methionine residue. The endogenous methionine oxidation level was evaluated in a small cohort (n ‫؍‬ 68) of heterozygous 34 carriers containing both healthy controls and AD patients. As expected, the proportion of oxidized residues varied from 0 to 10%, with an average of 5%. We therefore developed a standardized strategy for the unbiased, absolute quantification of ApoE4, based on performic acid oxidization of methionine. Once the sample workflow had been thoroughly validated, it was applied to the concomitant quantification of total ApoE and ApoE4 isoform in a large casecontrol study (n ‫؍‬ 669). The final measurements were consistent with most previously reported ApoE concentration values and confirm the influence of the different alleles on the protein expression level. Our results illustrate (i) the reliability of selected reaction monitoringbased assays and (ii) the value of the oxidization step for unbiased monitoring of methionine-containing proteotypic peptides. Furthermore, a statistical analysis indicated that neither total ApoE and ApoE4 levels nor the ApoE/ApoE4 ratio correlated with the diagnosis of AD. These findings reinforce the conclusions of previous studies in which plasma ApoE levels had no obvious clinical significance. Molecular & Cellular

Background Technological communication methods such as telephone calls and video calls can help prevent social isolation and loneliness in frail older adults during confinement. Objective Our objectives were to determine which virtual communication method (ie, telephone call or video call) was preferred by confined older hospital patients and nursing home residents and the variables influencing this preference. Methods The TOVID (Telephony Or Videophony for Isolated elDerly) study was a cross-sectional study that was designed to examine the preference between telephone calls and video calls among frail older adults who were either hospitalized in a geriatric acute care unit or institutionalized in a long-term care and nursing home during the COVID-19 confinement period. Results A total of 132 older people were surveyed between March 25 and May 11, 2020 (mean age 88.2 years, SD 6.2); 79 (59.8%) were women. Patients hospitalized in the geriatric acute care unit were more able to establish communication independently than residents institutionalized in the long-term care and nursing home (P=.03) and were more satisfied with their communication experiences (P=.02). Overall, older people tended to favor telephone calls (73/132, 55.3%) over video calls (59/132, 44.7%); however, their satisfaction degree was similar regardless of the chosen method (P=.1), with no effect of age (P=.97) or gender (P=.2). In the geriatric acute care unit, the satisfaction degrees were similar for telephone calls (40/41, 98%) and video calls (33/38, 87%) in older patients (P=.10). Conversely, in the long-term care and nursing home, residents were more satisfied with the use of video calls to communicate with their relatives (14/15, 93%) versus the use of telephone calls (6/12, 50%; P=.02). Conclusions Older people confined to health care settings were able to complete telephone calls more independently than video calls, and they tended to use telephone calls more often than video calls. The satisfaction degrees were similar with both modalities and even greater with video calls among long-term care and nursing home residents when they were given assistance to establish communication. Trial Registration ClinicalTrials.gov NCT04333849: https://www.clinicaltrials.gov/ct2/show/NCT04333849.

Background With the lack of effective therapy, chemoprevention, and vaccination against SARS-CoV-2, focusing on the immediate repurposing of existing drugs gives hope of curbing the COVID-19 pandemic. A recent unbiased genomics-guided tracing of the SARS-CoV-2 targets in human cells identified vitamin D among the three top-scoring molecules manifesting potential infection mitigation patterns. Growing pre-clinical and epidemiological observational data support this assumption. We hypothesized that vitamin D supplementation may improve the prognosis of COVID-19. The aim of this trial is to compare the effect of a single oral high dose of cholecalciferol versus a single oral standard dose on all-cause 14-day mortality rate in COVID-19 older adults at higher risk of worsening. Methods The COVIT-TRIAL study is an open-label, multicenter, randomized controlled superiority trial. Patients aged ≥ 65 years with COVID-19 (diagnosed within the preceding 3 days with RT-PCR and/or chest CT scan) and at least one worsening risk factor at the time of inclusion (i.e., age ≥ 75 years, or SpO2 ≤ 94% in room air, or PaO2/FiO2 ≤ 300 mmHg), having no contraindications to vitamin D supplementation, and having received no vitamin D supplementation > 800 IU/day during the preceding month are recruited. Participants are randomized either to high-dose cholecalciferol (two 200,000 IU drinking vials at once on the day of inclusion) or to standard-dose cholecalciferol (one 50,000 IU drinking vial on the day of inclusion). Two hundred sixty participants are recruited and followed up for 28 days. The primary outcome measure is all-cause mortality within 14 days of inclusion. Secondary outcomes are the score changes on the World Health Organization Ordinal Scale for Clinical Improvement (OSCI) scale for COVID-19, and the between-group comparison of safety. These outcomes are assessed at baseline, day 14, and day 28, together with the serum concentrations of 25(OH)D, creatinine, calcium, and albumin at baseline and day 7. Discussion COVIT-TRIAL is to our knowledge the first randomized controlled trial testing the effect of vitamin D supplementation on the prognosis of COVID-19 in high-risk older patients. High-dose vitamin D supplementation may be an effective, well-tolerated, and easily and immediately accessible treatment for COVID-19, the incidence of which increases dramatically and for which there are currently no scientifically validated treatments. Trial registration ClinicalTrials.govNCT04344041. Registered on 14 April 2020 Trial status Recruiting. Recruitment is expected to be completed in April 2021.

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Targeted mass spectrometry using selected reaction monitoring (SRM) has emerged as an alternative to immunoassays for protein quantification owing to faster development time and higher multiplexing capability. However, the SRM strategy is faced with the high complexity of peptide mixtures after trypsin digestion of whole plasma or the cellular proteome that most of the time causes contamination, irremediably, by interfering compounds in the transition channels monitored. This problem becomes increasingly acute when the targeted protein is present at a low concentration. In this work, the merit of laser-induced photo-dissociation in the visible region at 473 nm implemented in an hybrid quadrupole linear ion-trap mass spectrometer (photo-SRM) was evaluated for detection specificity of cysteine-containing peptides in a group of plasma proteins after tagging with a dabcyl chromophore. Compared with conventional SRM, photo-SRM chromatograms have improved detection specificity for most of peptides monitored. Comparison of the signals obtained for the best proteotypic peptides in SRM mode and those recorded by photo-SRM of cysteine-containing peptides for the same proteins reveals either increased (up to 10-fold) or similar signal to photo-SRM detection. Finally, photo-SRM has extended response linearity across a calibration plot obtained by diluting human plasma in rat plasma, down to the lowest concentrations. Hence, photo-SRM may advantageously complement conventional SRM in assay of proteins in complex biological matrices.

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