Long-term Effects Of Changes Research Articles

The impact of long-term changes in metabolic status on cardiovascular biomarkers and microvascular endothelial function in middle-aged men: a 25-year prospective study.

BackgroundThe aim of this analysis was to examine long-term effects of changes in metabolic status on microvascular endothelial function and cardiovascular diseases (CVD) biomarkers among physically active middle-aged men.MethodsMetabolically healthy men (n = 101, mean age 59.7 years), free of symptoms and treatment, have been prospectively observed for their lifestyle and CVD risk factors (observation period 24.7 years). At the latest follow-up (2011/2012) a set of CVD biomarkers was measured using enzyme-linked immunosorbent assay. Microvascular endothelial function was evaluated by means of the reactive hyperemia index (RHI) using Endo-PAT2000 system. At follow-up the participants were divided into metabolically healthy (0–1 metabolic parameters) and metabolically unhealthy (≥2 metabolic parameters) groups. Metabolic syndrome was defined according to the NCEP ATP III definition.ResultsTraditional metabolic risk factors were significantly associated with hsCRP, ox-LDL, Il-6, leptin and adiponectin/leptin ratio. Reactive hyperemia index was negatively related to body mass (p < 0.01), waist circumference (p < 0.05), triglycerides (p < 0.01), TG/HDL ratio (p < 0.01), uric acid (p < 0.05), sICAM-1 (p < 0.05) and Il-6 (p < 0.05), and positively to HDL-C (p < 0.01) and leisure-time physical activity (p < 0.01). Men who maintained metabolically healthy status (n = 47) through the observation had significantly lower hsCRP and uric acid (p < 0.05), higher adiponectin/leptin ratio (p < 0.05), higher mean RHI and lower prevalence of endothelial dysfunction (p < 0.05) as compared to the metabolically unhealthy group (n = 54). Regular physical activity level was significantly higher among metabolically healthy individuals during the whole observation.ConclusionsEven subtle changes in metabolic profile influence inflammatory biomarkers and microvascular endothelial function. Leptin, adiponectin/leptin ratio and hsCRP are significant predictors of metabolic profile. Interleukine-6 and sICAM-1 may be used as indicators of early endothelial dysfunction in asymptomatic men. High leisure-time physical activity level is an important contributor of metabolically healthy profile through middle adulthood.

Farmers’ Perceptions about Adaptation Practices to Climate Change and Barriers to Adaptation: A Micro-Level Study in Ghana

This study analyzed the farmer-perceived importance of adaptation practices to climate change and examined the barriers that impede adaptation. Perceptions about causes and effects of long-term changes in climatic variables were also investigated. A total of 100 farmer-households were randomly selected from four communities in the Lawra district of Ghana. Data was collected using semi-structured questionnaires and focus group discussions (FGDs). The results showed that 87% of respondents perceived a decrease in rainfall amount, while 82% perceived an increase in temperature over the past 10 years. The study revealed that adaptation was largely in response to dry spells and droughts (93.2%) rather than floods. About 67% of respondents have adjusted their farming activities in response to climate change. Empirical results of the weighted average index analysis showed that farmers ranked improved crop varieties and irrigation as the most important adaptation measures. It also revealed that farmers lacked the capacity to implement the highly ranked adaptation practices. The problem confrontation index analysis showed that unpredictable weather, high cost of farm inputs, limited access to weather information, and lack of water resources were the most critical barriers to adaptation. This analysis of adaptation practices and constraints at farmer level will help facilitate government policy formulation and implementation.

Constraints on southern hemisphere tropical climate change during the Little Ice Age and Younger Dryas based on glacier modeling of the Quelccaya Ice Cap, Peru

Improving the late Quaternary paleoclimate record through climate interpretations of low-latitude glacier length changes advances our understanding of past climate change events and the mechanisms for past, present, and future climate change. Paleotemperature reconstructions at low-latitude glaciers are uniquely fruitful because they can provide both site-specific information and enhanced understanding of regional-scale variations due to the structure of the tropical atmosphere. We produce Little Ice Age (LIA) and Younger Dryas (YD) paleoclimate reconstructions for the Huancané outlet glacier of the Quelccaya Ice Cap (QIC) and low-latitude southern hemisphere regional sea surface temperatures (SSTs) using a coupled ice-flow and energy balance model. We also model the effects of long-term changes in the summit temperature and precipitiation rate and the effects of interannual climate variability on the Huancané glacier length. We find temperature to be the dominant climate driver of glacier length change. Also, we find that interannual climate variability cannot adequately explain glacier advances inferred from the geomorphic record, necessitating that these features were formed during past colder climates. To constrain our LIA reconstruction, we incorporate the QIC ice core record, finding a LIA air temperature cooling at the ice cap of between ∼0.7 °C and ∼1.1 °C and ∼0.4 °C and regional SSTs cooling of ∼0.6 °C. For the YD paleoclimate reconstructions, we propose two limits on the precipitation rate, since the ice core record does not extend into the Pleistocene: 1) the precipitation rate scales with the Clausius-Clapeyron relationship (upper limit on cooling) and 2) the precipitation rate increases by 40% (lower limit on cooling), which is an increase about twice as great as the regional increases realized in GCM simulations for the period. The first limit requires ∼1.6 °C cooling in ice cap air temperatures and ∼0.9 °C cooling in SSTs, and the second limit requires ∼1.0 °C cooling in ice cap air temperatures and ∼0.5 °C cooling in SSTs. Our temperature reconstructions are in good agreement with the magnitude and trend of GCM simulations that incorporate the forcing mechanisms hypothesized to have caused these climate change events.

Effect of long-term changes of marine factors on river mouths

The main marine hydrological factors that influence the regime and structure of river mouths, including the mean (background) sea level, waves, tides, and storm surges, are discussed. Special attention is given to the long-term changes in the water levels of the World Ocean and in related seas that occurred during the XIX–XX centuries and to the predicted considerable sea level rise in the XXI century. The role of natural and anthropogenic land subsidence in variations of water levels in river deltas is assessed. The main hydrological and morphological processes at river mouths related to the sea level rise are considered. Special attention is given to the discussion of insufficiently studied problems such as changes in the characteristics of tides and storm surges under the condition of the sea level rise and nonlinear interaction of these phenomena.

The concurrent and carry over effects of long term changes in energy intake before insemination on pregnancy per artificial insemination in heifers

Follicle development in a period of negative energy balance (NEB), as experienced by the postpartum dairy cow, could be affected by undesirable metabolic changes, and may contain a developmentally incompetent oocyte with an impaired potential to establish a pregnancy. A differential feeding model in heifers was developed to evaluate the concurrent and carryover effects of reduced energy intake before insemination on pregnancy per artificial insemination (P/AI). Heifers were randomly assigned to either (i) control feed intake group (CF), n=68, 1.3 times estimated maintenance energy (M) requirements for 50 days and 2.0 M for 83 days or (ii) restricted feed intake (RF), n=88, 0.65 M for 50 days and 2.0 M for 83 days. Pregnancy per AI was determined by transrectal ultrasonography at day 30 following AI. Despite significant loss of live weight (LW; 5.8±2.1 vs 70.5±2.8kg, respectively) and body condition score (BCS; 0.05±0.03 vs 0.45±0.03) and a significant elevation in systemic concentrations of non-esterified fatty acids in RF heifers, there was no concurrent effect on P/AI (69 vs 72%) following AI at day 50. However, there was a carryover effect on P/AI as there was an 18 percentage point difference (64 vs 82%) between CF and RF heifers following AI on day 93. The results of the study indicate that a reduction in energy intake for a 50-day period pre-insemination had no concurrent effect but had a positive carryover effect on P/AI.

Snow avalanches in western Canada: investigating change in occurrence rates and implications for risk assessment and mitigation

Snow avalanche frequency and magnitude, required for risk analysis, are best determined using historical occurrence records. In Canada, reliable records are sparse and relatively short term, extending back 30–50 years. Some Canadian avalanche forecasters suspect that climate change has increased avalanche activity in recent years. Should an increasing trend exist, analyses based on historical occurrence rates would underestimate future risk to people and infrastructure in mountain regions. We analyse 30 years of occurrence records to investigate whether a trend exists, and assess its strength. A Bayesian hierarchical model is used to estimate occurrence rate trends across six geographical zones in western Canada. The results suggest that natural avalanche occurrence rates have decreased or stayed constant; however, there is a very high level of uncertainty. This uncertainty will need to be factored into decision-making processes. To assist in this, we discuss the effect of long-term changes in avalanche occurrence rates in terms of consequences and vulnerability. We also recommend strategies for improving mitigation practices so that avalanche control operations can better adapt to changing and less predictable environments.

Capital and Knowledge: Integrating Arrow’s Learning-by-Doing, the Walrasian Equilibrium Theory and Neoclassical Growth Theory

This article proposes a neoclassical growth model with endogenous capital accumulation and knowledge creation. The model integrates Arrow’s learning by doing, Uzawa’s two-sector growth model and Walrasian general equilibrium theory. We use a utility function, which determines leisure time, saving and consumption with utility optimization without leading to a higher dimensional dynamic system like the Ramsey approach. The dynamics of J-household economy is described by a ( J + 1)-dimensional differential equations system. We simulate the motion of the model and demonstrate transitional and long-term effects of changes in the propensity to save, the propensity to use leisure time, the population, the learning-by-doing efficiency and knowledge utilization efficiency. The comparative dynamic analysis provides some insights into issues related to inequality and growth. JEL Classification: D51, D31, O41, E13

A Review of the Effect of Dietary Composition on Fasting Substrate Oxidation in Healthy and Overweight Subjects

Aim: The purpose of this review was to assess existing evidence on the effects of chronic dietary macronutrient composition on substrate oxidation during a fasted state in healthy and overweight subjects. Methods: A systematic review of studies was conducted across five databases. Studies were included if they were English language studies of human adults, ≥19 years, used indirect calorimetry (ventilated hood technique), specified dietary macronutrient composition, and measured substrate oxidation. Results: There was no evidence that variations of a typical, non-experimental diet influenced rate or ratio of substrate utilization, however there may be an upper and lower threshold for when macronutrient composition may directly alter preferences for fuel oxidation rates during a fasted state. Conclusion: This review indicates that macronutrient composition of a wide range of typical, non-experimental dietary fat and carbohydrate intakes has no effect on fasting substrate oxidation. This suggests that strict control of dietary intake prior to fasting indirect calorimetry measurements may be an unnecessary burden for study participants. Further research into the effects of long-term changes in isocaloric macronutrient shift is required.

Whole-genome analyses of DS-1-like human G2P[4] and G8P[4] rotavirus strains from Eastern, Western and Southern Africa.

Group A rotaviruses (RVAs) with distinct G and P genotype combinations have been reported globally. We report the genome composition and possible origin of seven G8P[4] and five G2P[4] human RVA strains based on the genetic evolution of all 11 genome segments at the nucleotide level. Twelve RVA ELISA positive stool samples collected in the representative countries of Eastern, Southern and West Africa during the 2007-2012 surveillance seasons were subjected to sequencing using the Ion Torrent PGM and Illumina MiSeq platforms. A reference-based assembly was performed using CLC Bio's clc_ref_assemble_long program, and full-genome consensus sequences were obtained. With the exception of the neutralising antigen, VP7, all study strains exhibited the DS-1-like genome constellation (P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2) and clustered phylogenetically with reference strains having a DS-1-like genetic backbone. Comparison of the nucleotide and amino acid sequences with selected global cognate genome segments revealed nucleotide and amino acid sequence identities of 81.7-100 % and 90.6-100 %, respectively, with NSP4 gene segment showing the most diversity among the strains. Bayesian analyses of all gene sequences to estimate the time of divergence of the lineage indicated that divergence times ranged from 16 to 44 years, except for the NSP4 gene where the lineage seemed to arise in the more distant past at an estimated 203 years ago. However, the long-term effects of changes found within the NSP4 genome segment should be further explored, and thus we recommend continued whole-genome analyses from larger sample sets to determine the evolutionary mechanisms of the DS-1-like strains collected in Africa.

Nonreassuring fetal heart rate decreases heart rate variability in newborn infants.

Nonreassuring fetal status (NRFS) refers to a compromised fetal condition which implies hypoxia. The influence of intrapartum hypoxia on autonomic nervous system function in early postnatal life is unknown. This study explored the influence of NRFS on the heart rate variability (HRV) of newborn infants. Singleton newborn infants delivered through Cesarean delivery (CD) with indications of elective purpose (n = 32), dystocia (n = 29), or NRFS (n = 22), and through vaginal birth (VB) (n = 80) were consecutively collected. HRV parameters including standard deviation of average NN intervals (SDANN), low frequency (LF), high frequency (HF), LF%, HF%, and total power (TP), were obtained for analysis in 3 days postpartum. An independent t-test or one-way ANOVA was used to compare differences in numeric data. SDANN, HF, HF%, and TP of newborn infants in the VB group were significantly higher than those in the CD group. The NRFS group had significantly lower SDANN, HF, and TP than those of the elective group, and significantly lower HF, HF%, and TP than those of the dystocia group. Newborn infants delivered through Cesarean section had lower HRV, especially those who experienced NRFS during labor. The long-term effects of changes of HRV in neonates require further evaluation.

Use of System Dynamics to Understand Long-Term Impact of Climate Change on Pavement Performance and Maintenance Cost

An increase in the vulnerability of the nation's roadway network to changes in climatic conditions has become an issue of significant concern. Heavy rainfall and high temperatures are examples of climatic factors that can affect pavement performance and conditions in a detrimental way. Some of these effects, specifically on costs associated with constructing and maintaining roads, may not be significant in the short term but may become significant in the long term. The objective of this study was to present a framework to use system dynamics to understand the long-term impact of climate change on pavement performance and maintenance activity. A system dynamics model was created with available pavement performance and climate change data, and the effects on various key factors, such as pavement life and maintenance cost, were evaluated through simulation. Preliminary results show that the long-term effects of changes in air temperature, rainfall, seawater–level rise, and number of hurricanes on pavement performance are significant and that costs are expected to increase significantly (&gt;160% in 100 years) and nonlinearly. From these findings, recommendations are made for obtaining more accurate and reliable data on relevant climate change factors and for using a system dynamics approach to integrate the multi-disciplinary topics of climate change, pavement design and performance, and economics into comprehensive studies.

An Evaluation of Temporal Changes in Sediment Accumulation and Impacts on Carbon Burial in Mobile Bay, Alabama, USA

The estuarine environment can serve as either a source or sink of carbon relative to the coastal ocean carbon budget. A variety of time-dependent processes such as sedimentation, carbon supply, and productivity dictate how estuarine systems operate, and Mobile Bay is a system that has experienced both natural and anthropogenic perturbations that influenced depositional processes and carbon cycling. Sediments from eight box cores provide a record of change in bulk sediment accumulation and carbon burial over the past 110 years. Accumulation rates in the central part of the basin (0.09 g cm−2) were 60–80 % less than those observed at the head (0.361 g cm−2) and mouth (0.564 g cm−2) of the bay. Sediment accumulation in the central bay decreased during the past 90 years in response to both anthropogenic (causeway construction) and natural (tropical cyclones) perturbations. Sediment accumulation inevitably increased the residence time of organic carbon in the oxic zone, as observed in modeled remineralization rates, and reduced the overall carbon burial. Such observations highlight the critical balance among sediment accumulation, carbon remineralization, and carbon burial in dynamic coastal environments. Time-series analysis based solely on short-term observation would not capture the long-term effects of changes in sedimentation on carbon cycling. Identifying these relationships over longer timescales (multi-annual to decadal) will provide a far better evaluation of coastal ocean carbon budgets.

Relation Between Self-Reported Physical Activity Level, Fitness, and Cardiometabolic Risk

Physical activity and cardiorespiratory fitness are associated with improved cardiovascular health and reduced all-cause mortality. The relation between self-reported physical activity, objective physical fitness, and the association of each with cardiometabolic risk has not been fully described. We studied 2,800 healthy Brazilian subjects referred for an employer-sponsored health screening. Physical activity level was determined as "low," "moderate," or "high" with the International Physical Activity Questionnaire: Short Form (IPAQ-SF). Fitness was measured as METs achieved on a maximal, symptom-limited, treadmill stress test. Using multivariate linear regression analysis, we calculated age, gender, and smoking-adjusted correlation coefficients among IPAQ-SF, fitness, and cardiometabolic risk factors. Mean age of study participants was 43 ± 9 years; 81% were men, and 43% were highly active. Mean METs achieved was 12 ± 2. IPAQ-SF category and fitness were moderately correlated (r = 0.377). Compared with IPAQ-SF category, fitness was better correlated with cardiometabolic risk factors including anthropomorphic measurements, blood pressure, fasting blood glucose, dyslipidemia, high-sensitivity C-reactive protein, and hepatic steatosis (all p <0.01). Among these, anthropomorphic measurements, blood pressure, high-sensitivity C-reactive protein, and hepatic steatosis had the largest discrepancies in correlation, whereas lipid factors had the least discrepant correlation. When IPAQ-SF and fitness were discordant, poor fitness drove associations with elevated cardiometabolic risk. In conclusion, self-reported physical activity level and directly measured fitness are moderately correlated, and the latter is more strongly associated with a protective cardiovascular risk profile.

Resilience of upland soils to long term environmental changes

The effect of long-term changes in land-use, pollution deposition and climate change on upland soils was evaluated by resurveying a large set of sites in a mountain landscape in the UK, which were initially sampled forty years ago. Unexpectedly, despite the length of time between sampling dates, no significant changes in pH, soil exchangeable base cations or C and N percentage content by weight were observed across a range of soil type and parent material. This suggests that the soils have been relatively resistant to the large changes in the environmental pressures experienced in the past forty years, which include a 1.5°C increase in mean temperature; the peak of UK sulphur deposition in around 1970, followed by ~90% deposition reduction; long-term increases in nitrogen deposition; and major changes in grazing intensity. These results suggest that upland soils may be considerably more resilient to the future environmental changes than many previous assessments have suggested.

The times they are a‐changin’: time to change glaucoma management

The times they are a‐changin’: time to change glaucoma management

Changes in physical activity in leisure time and the risk of myocardial infarction, ischemic heart disease, and all-cause mortality

Physical activity is associated to a lower risk of mortality from all-causes and from coronary heart disease. The long-term effects of changes in physical activity on coronary heart disease are, however, less known. We examined the association between changes in leisure time physical activity and the risk of myocardial infarction (MI), ischemic heart disease (IHD), and all-cause mortality as well as changes in blood pressure in 4,487 men and 5,956 women in the Copenhagen City Heart Study. Physical activity was measured in 1976-1978 and 1981-1983 and participants were followed in nation-wide registers until 2009. Men who decreased physical activity by at least two levels and women who decreased by one level had a higher risk of MI relatively to an unchanged physical activity level (hazard ratio [HR] = 1.74, 95% confidence interval [95% CI]: 1.17-2.60 and HR = 1.30, 95% CI: 1.03-1.65). Similar associations were found for IHD although only significant in women. In all-cause mortality, men who increased physical activity had a lower risk and both men and women who reduced physical activity had a higher risk compared to an unchanged physical activity level. No association between changes in physical activity and blood pressure was observed. Findings from this prospective study suggest that changes in physical activity affect the risk of MI, IHD and all-cause mortality. A decrease in physical activity was associated to a higher risk of coronary heart disease.

Temporal changes in species interactions in simple aquatic bacterial communities

BackgroundOrganisms modify their environment and in doing so change the quantity and possibly the quality of available resources. Due to the two-way relationship between organisms and their resource environment, and the complexity it brings to biological communities, measuring species interactions reliably in any biological system is a challenging task. As the resource environment changes, the intensity and even the sign of interactions may vary in time. We used Serratia marcescens and Novosphingobium capsulatum bacteria to study how the interaction between resource environment and organisms influence the growth of the bacterial species during circa 200 generations. We used a sterile-filtering method to measure how changes in resource environment are reflected in growth rates of the two species.ResultsChanges in the resource environment caused complex time and species composition-dependent effects on bacterial growth performance. Variation in the quality of the growth medium indicated existence of temporally fluctuating within-species facilitation and inhibition, and between-species asymmetric facilitation.ConclusionsThe interactions between the community members could not be fully predicted based only on the knowledge of the growth performance of each member in isolation. Growth dynamics in sterile-filtered samples of the conditioned growth medium can reveal both biologically meaningful changes in resource availability and temporally changing facilitative resource-mediated interactions between study species. This is the first study we are aware of where the filter-sterilization – growth assay method is applied to study the effect of long-term changes in the environment on species interactions.

Long-Term Effects of Changes in Cardiorespiratory Fitness and Body Mass Index on All-Cause and Cardiovascular Disease Mortality in Men: The Aerobics Center Longitudinal Study

Long-Term Effects of Changes in Cardiorespiratory Fitness and Body Mass Index on All-Cause and Cardiovascular Disease Mortality in Men: The Aerobics Center Longitudinal Study

Long-Term Effects of Changes in Cardiorespiratory Fitness and Body Mass Index on All-Cause and Cardiovascular Disease Mortality in Men

Background— The combined associations of changes in cardiorespiratory fitness and body mass index (BMI) with mortality remain controversial and uncertain. Methods and Results— We examined the independent and combined associations of changes in fitness and BMI with all-cause and cardiovascular disease (CVD) mortality in 14 345 men (mean age 44 years) with at least 2 medical examinations. Fitness, in metabolic equivalents (METs), was estimated from a maximal treadmill test. BMI was calculated using measured weight and height. Changes in fitness and BMI between the baseline and last examinations over 6.3 years were classified into loss, stable, or gain groups. During 11.4 years of follow-up after the last examination, 914 all-cause and 300 CVD deaths occurred. The hazard ratios (95% confidence intervals) of all-cause and CVD mortality were 0.70 (0.59–0.83) and 0.73 (0.54–0.98) for stable fitness, and 0.61 (0.51–0.73) and 0.58 (0.42–0.80) for fitness gain, respectively, compared with fitness loss in multivariable analyses including BMI change. Every 1-MET improvement was associated with 15% and 19% lower risk of all-cause and CVD mortality, respectively. BMI change was not associated with all-cause or CVD mortality after adjusting for possible confounders and fitness change. In the combined analyses, men who lost fitness had higher all-cause and CVD mortality risks regardless of BMI change. Conclusions— Maintaining or improving fitness is associated with a lower risk of all-cause and CVD mortality in men. Preventing age-associated fitness loss is important for longevity regardless of BMI change.

Future projections of surface UV-B in a changing climate

[1] Results of comprehensive long-term simulations of surface all-sky and clear-sky ultraviolet (UV) radiation through 1960–2100 are presented. A new earth system model, MIROC-ESM-CHEM, is used for the simulation, which considers key processes that change the surface UV radiation: atmospheric dynamics and chemistry affecting ozone in the stratosphere and troposphere, aerosols and clouds in the troposphere, and changes in surface albedo with sea ice and snow cover. In contrast to previous assessments considering only the effect of long-term change in stratospheric ozone, the simulated long-term behavior of UV radiation in this study is strongly affected by other processes. In one of two simulations, all-sky UV radiation in the northern midlatitudes is projected to increase in the 21st century despite the expected recovery of the stratospheric ozone layer. Reductions in aerosols and clouds are expected to overcompensate for the effect of ozone recovery. The results are sensitive to the future socioeconomic scenario, describing GHG concentrations and emissions of aerosol and ozone precursors in the troposphere. The interannual variability of UV radiation associated with the 11 year solar cycle and local processes is also discussed.