RESUMO
Background: The reference standard for the molecular diagnostic testing for COVID-19 is the use of nasopharyngeal or combined nasopharyngeal and oropharyngeal (NP/OP) swabs. Saliva has been proposed as a minimally invasive specimen whose collection reduces the risks for health care personnel. Objective: To assess the suitability of saliva for COVID-19 diagnosis as a replacement of the reference standard NP/OP swab in the setting of a tertiary care pediatric unit. Study design: A paired study based in the prospective cohort design in patients suspected of having COVID-19. Methods: RT-PCR was used to detect SARS-CoV-2 in paired samples of saliva and NP/OP swab collected from May through August 2020 from 156 pediatric participants, of whom 128 has at least one comorbidity and 91 showed clinical symptoms related to SARS-CoV-2 infection. Additionally, we studied a group of 326 members of the hospital staff, of whom 271 had symptoms related to SARS-CoV-2 infection. Results: In the group of pediatric participants the sensitivity of the diagnostic test in saliva was 82.3% (95% CI 56.6-96.2) and the specificity 95.6% (95% CI 90.8-98.4). The prevalence of COVID-19 was 10.9% (17/156). In 6 of the 23 participants who tested positive for SARS-CoV-2 in at least one specimen type, the virus was detected in saliva but not in NP/OP swab, while in 3 participants the NP/OP swab was positive and saliva negative. In the group of adults, the sensitivity of the test in saliva was 77.8% (95% CI 67.2-86.3) and prevalence 24.8% (81/326). Discordant results between the two types of specimens showed a significant association with low viral load in the pharynx of adults but not of pediatric participants. Interpretation: In the context of a pediatric tertiary care hospital, the sensibility of the test in saliva is not high enough to replace the use of NP/OP swab for COVID-19 diagnosis. Neither NP/OP swab nor saliva could detect all the participants infected with SARS-CoV-2.
RESUMO
Because of the importance of cholesterol metabolism in the physiopathogenesis of dementia, and knowing the function of ATP-binding cassette A1 transporter (ABCA1) as a cholesterol flow pump at the cellular and cerebral level, it has been noted that the ABCA1 gene may be a good candidate for disease study. In order to evaluate the relationship between ABCA1 genetic variants and the risk of Alzheimer's disease and other dementia in Mexican individuals, we examined three ABCA1 polymorphisms located in the exonic region (rs2230808, rs2066718, rs2230806) and two in the promoter region (rs1800977, rs2422493) in a group of 557 normal controls and 221 cases of dementia. It was possible to distinguish one protective haplotype: CCCCGC (OR = 0,502, 95% CI = 0,370-0,681, p < 0.001), and one risk haplotype TCCCAT (OR = 2208, 95% CI = 1609-3031, p < 0.000) for the development of dementia. The results suggest that ABCA1 plays an important role in the pathophysiological mechanisms for the development of dementia.