Between-Visit Variability in FEV1 as a Diagnostic Test for Asthma in Adults.

RATIONALE: The reliability of using between-visit variation in forced expiratory volume in 1 second (FEV1) to diagnose asthma is understudied, and hence uncertain. OBJECTIVE: To determine whether FEV1 variability measured over recurrent visits is significantly associated with a diagnosis of current asthma. METHODS: Randomly selected adults (N = 964) with a history of physician-diagnosed asthma were studied from 2005 to 2007 and from 2012 to 2016. A diagnosis of current asthma was confirmed in those participants who exhibited bronchial hyperresponsiveness to methacholine and/or acute worsening of asthma symptoms while being weaned off asthma medications. Regression analyses and receiver operating curves were used to evaluate the ability of between-visit FEV1 variability to diagnose asthma. RESULTS: A current diagnosis of asthma was confirmed in 584 of 964 participants (60%). Between-visit absolute variability in FEV1 was significantly greater in those in whom current asthma was confirmed, compared with those in whom current asthma was ruled out (7.3% vs. 4.8%; mean difference between the two groups, 2.5%; 95% confidence interval, 1.7-3.3%). However, a 12% and 200-ml between-visit variation in FEV1, which is the diagnostic threshold recommended by Global Initiative for Asthma, exhibited a sensitivity of only 0.17 and a specificity of 0.94 for confirming current asthma. A between-visit absolute variability in FEV1 ≥ 12% and 200 ml increased the pretest probability of asthma from 60% to a posttest probability of 81%. CONCLUSIONS: A 12% and 200-ml between-visit variation in FEV1, if present, has reasonably good specificity for diagnosing asthma, but has poor sensitivity compared with bronchial challenge testing. Between-visit variability in FEV1 is a relatively unhelpful test to establish a diagnosis of asthma.

An analysis of blood donation barriers experienced by North American and Caribbean university students in Grenada, West Indies.

OBJECTIVES: To estimate the associations of nationality, university program, donation history and gender, with blood donation barriers experienced by non-donating students on the day of a campus blood drive. This project focused particularly on nationality and the effect of the different blood donation cultures in the students' countries of origin. METHODS: A retrospective cohort study of 398 North American and Caribbean university students was conducted at St. George's University, Grenada, in 2010. Data were collected from non-donating students on campus while a blood drive was taking place. Log-binomial regression was used to estimate associations between the exposures of interest and donation barriers experienced by the students. RESULTS: North American (voluntary blood donation culture) students were more likely than Caribbean (replacement blood donation culture) students to experience "Lack of Time" (relative risk (RR) = 1.57; 95% confidence interval (CI): 1.19-2.07) and "Lack of Eligibility" (RR = 1.55; 95% CI: 1.08-2.22) as barriers to donation. Conversely, Caribbean students were a third as likely to state "Lack of Incentive" (RR = 0.32; 95% CI: 0.20-0.50), "Fear of Infection" (RR = 0.35; 95% CI: 0.21-0.58), and "Fear of Needles" (RR = 0.32; 95% CI: 0.21-0.48) were barriers than North American students. CONCLUSIONS: University students from voluntary blood donation cultures are likely to experience different barriers to donation than those from replacement cultures. Knowledge of barriers that students from contrasting blood donation systems face provides valuable information for blood drive promotion in university student populations that contain multiple nationalities.

Mitogenic action of hypoxia upon cutaneous neuroepithelial cells in developing zebrafish.

In zebrafish, cutaneous neuroepithelial cells (NECs) contain serotonin (5-HT) and are believed to initiate physiological and behavioral responses to hypoxia during embryonic and early larval development, when mature gills and O2 chemoreceptors are not yet present. The number of skin NECs rapidly declines as embryos develop into larvae, but acclimation to hypoxia leads to retention of a greater number of these cells. We hypothesized that reduction of the partial pressure of oxygen (PO2 ) in water would stimulate mitosis in cutaneous NECs in zebrafish. Zebrafish were exposed to 5-bromo-2'-deoxyuridine (BrdU) and immunolabeled with antibodies against serotonin and BrdU to identify mitotic skin cells, including NECs. Cells were imaged and quantified using confocal microscopy. From embryonic to larval stages, we observed an overall increase in the number of BrdU-positive cells in the skin, but a decrease in BrdU-positive serotonergic NECs. Exposure of larvae to hypoxia (PO2 = 30 mmHg) in vivo for 24 h produced a 1.7-fold increase in the number of NECs labeled with BrdU. We conclude that under normal environmental PO2 the population of cutaneous NECs declines due to a decrease in mitotic activity. During environmental hypoxia, the number of NECs undergoing cell division in the skin is increased, and this promotes retention of NECs under these conditions. These data demonstrate the direct action of hypoxia upon the cell cycle of cutaneous NECs in developing zebrafish, and support the notion that cutaneous NECs are embryonic O2 chemoreceptors. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 789-801, 2017.