Pulmonary arterial pressure: repeated measures and dynamics due to changes in altitude and age

2022 Spring.Includes bibliographical references.High Altitude Disease (HAD) in cattle is a consequence of pulmonary hypertension (PH) induced by hypoxia at elevations > 1,500 m. Pulmonary arterial pressure (PAP) is a phenotypic indicator of animal susceptibility to PH and HAD and is moderately heritable (h2 = 0.26 to 0.34). The goal of this thesis was to evaluate repeated measures of PAP and dynamics. This goal was achieved with two studies and three objectives: 1) to explore and estimate correlations between different ages and elevations, 2) to determine usefulness of yearling moderate altitude PAP in beef bulls that are transported to high elevation for short- and longer-term management, and 3) to determine usefulness of feedlot entry PAP to additional PAP measures as the cattle approach finishing and harvest. The objective of Study I (Chapter 3) was to determine significant variables and estimate correlation between PAP measurements at moderate altitude and high altitude at differing ages. This scenario often occurs in the Western U.S. beef industry. Data consisted of breed, sire, mean PAP (mPAP) measures at each collection date, elevation, and bull age, from 2017-2019 (n = 89) spring-born bulls at the Colorado State University (CSU) Agriculture Research, Development, and Education Center (ARDEC; 1,524 m). A potential 5 PAP measurements were collected from each bull: 1) Weaning PAP at ARDEC (1,525 m); 2) Yearling PAP at ARDEC; 3) PAP after acclimating for 28 days at Fort Lewis College (FLC; 2,470 m), Hesperus, CO; 4) before returning to ARDEC from FLC after 110 days at FLC; and 5) after re-acclimating for 57 days to the moderate elevation at ARDEC when the bulls were 557 ± 2.92 d (18 mo) of age. In model development, yearling PAP measurement, elevation, and age were determined to be important (P < 0.05) sources of variation. Also, PAP increased (P < 0.05) from moderate altitude to high altitude. In Study II (Chapter 4), yearling PAP in the model accounted for more variation in the prediction of the initial high-altitude PAP than it did in the prediction of the subsequent high altitude PAP measurements. Results of this study suggested that the yearling PAP measurement collected at 1,525 m was only a moderate predictor of a PAP measurement collected after 21 days at 2,470 m and these types of predictions weaken after ~ 90 days at high elevation. Overall, Study II (Chapter 4) suggested that as time increased (p < 0.05) between the mPAP measures the amount of variation accounted by the initial mPAP measure declined (p < 0.05). However, PAP has been considered to be the most accurate indicator of an individual's susceptibility to HAD if is measured at high altitude and near 18 months of age (Holt and Callen, 2007). This thesis suggested that yearling PAP measured at moderate elevations was a moderate and short-term indicator of future PAP performance in beef bulls when moving to high altitudes. Yearling PAP measurements are likely less indicative of PAP, the longer bulls reside at high elevation. It should be noted that high-altitude PAP observations will likely have higher correlations and be a stronger indicator to future high-altitude PAP measures. The altitude of the ARDEC facility (1,525 m) of CSU is moderate; therefore, questionable if it yields enough hypoxic stress to determine if a bull has PAP that will be acceptable or unacceptable for lifetime residence in a mountainous beef production system. Breed was not a significant variable in this thesis. This is likely due to limited numbers being evaluated in each breed. To further study breed influence, greater numbers of bulls being analyzed is necessitated. Therefore, this challenge warrants additional research when considering the diversity of beef operations in the Western US

Crop Residue Management- Part of Farming in the Future

Farming systems that manage crop residue are becoming more and more popular today. Interest and enthusiasm in crop residue management indicates that these farming practices will be part of farming in the future. Profit and conservation are driving these upward trends

Stability and Change in Typical Intellectual Engagement in Old Age Across 5 Years

Objectives. Typical intellectual engagement (TIE) is related to cognitive development across the life span, but the development of TIE itself has not been examined. In the present study, structural change, differential change, absolute change, stability of divergence, and the generality of changes in the 4 TIE-factors abstract thinking, problem solving, reading, and intellectual curiosity across 5 years were examined in older adults. Method. Data came from the Zurich Longitudinal Study on Cognitive Aging. Two hundred and thirty-three individuals, 73 years on average at first measurement occasion (2005), were reassessed after 5 years. Confirmatory factor analyses and latent change score models were applied. Results. Factor covariances were equal across time, implying structural stability. Coefficients for differential stability were around .80, implying small significant mean-level changes for problem solving and intellectual curiosity. No changes in divergence emerged. Change correlations between the factors were in the medium to large range. Discussion. Across 5 years, TIE remained relatively stable on a group level. However, pronounced interindividual differences emerged. Also, although the changes in factors shared a substantial amount of variance, the development of the factors was not completely paralle

Five views of a secret: does cognition change during middle adulthood?

This study examined five aspects of change (or stability) in cognitive abilities in middle adulthood across a 12-year period. Data come from the Interdisciplinary Study on Adult Development. The sample consisted of N=346 adults (43.8years on average, 48.6% female). In total, 11 cognitive tests were administered to assess fluid and crystallized intelligence, memory, and processing speed. In a first series of analyses, strong measurement invariance was established. Subsequently, structural stability, differential stability, stability of divergence, absolute stability, and the generality of changes were examined. Factor covariances were shown to be equal across time, implying structural stability. Stability coefficients were around .90 for fluid and crystallized intelligence, and speed, indicating high, yet not perfect differential stability. The coefficient for memory was .58. Only in processing speed the variance increased across time, indicating heterogeneity in interindividual development. Significant mean-level changes emerged, with an increase in crystallized intelligence and decline in the other three abilities. A number of correlations among changes in cognitive abilities were significant, implying that cognitive changes in middle adulthood share up to 50 percent of varianc

Predictors of cognitive complaints in older adults: a mixture regression approach

The present paper examined four hypotheses regarding the nature of cognitive complaints in older adults. Analyzing data from 607 participants (mean age=62.9years, SD=0.92years, 59-65years), we tested the influence of actual cognitive test performance, negative age stereotypes, depressive symptoms, neuroticism, and conscientiousness on cognitive complaints. Bivariate correlations confirmed relations of all hypothesized predictors with cognitive complaints. However, considering all predictors simultaneously in an OLS regression analysis, particularly depressive symptoms and neuroticism were revealed as accounting for large proportions of variance in cognitive complaints. Utilizing mixture regression analyses, evidence for distinct subgroups was obtained in which cognitive complaints were explained by different predictor pattern

The factorial structure and external validity of the prospective and retrospective memory questionnaire in older adults

The factorial structure of the Prospective and Retrospective Memory Questionnaire (PRMQ) was investigated in a sample of 336 older adults (aged 66-81years). Confirmatory factor analyses showed that a bifactor model of two correlated factors of prospective and retrospective memory problems and two uncorrelated group factors of positively and negatively worded items had the best fit. Such a model can be seen as a multitrait-multi-method model that separates the substantive and methodological components among the items of the PRMQ. Correlations of the four factors with external criteria (affect, neuroticism, prospective, and retrospective memory performance) revealed that the item wording factors mainly correlate with the affect variables, whereas the prospective and retrospective memory problem factors were differentially associated with memory performance. As a conceptual conclusion, these differential correlations give support to the discriminant validity of subjective prospective versus retrospective memory problem

Intraindividual reaction time variability predicts prospective memory failures in older adults

This study investigated the relationship between intraindividual variability (IIV) in reaction time and prospective memory errors in older adults using data from the Zurich Longitudinal Study of Cognitive Aging (n = 336 individuals aged 66–81 years). The results indicated that increased IIV measured from independent tasks was associated with a greater proportion of prospective memory errors. These significant findings were not influenced by age and did not vary according to prospective memory cue type. Variability is thought to reflect fluctuations in attentional and executive control and these attentional processes may also impact on prospective memory through failure to detect the target cue. The findings suggest, therefore, that measures of variability may have some potential in the identification of older persons who are more vulnerable to everyday errors such as prospective memory failures