Permafrost carbon feedback (PCF) modeling has focused on gradual thaw of near-surface permafrost leading to enhanced carbon dioxide and methane emissions that accelerate global climate warming. These state-of-the-art land models have yet to incorporate deeper, abrupt thaw in the PCF. Here we use model data, supported by field observations, radiocarbon dating, and remote sensing, to show that methane and carbon dioxide emissions from abrupt thaw beneath thermokarst lakes will more than double radiative forcing from circumpolar permafrost-soil carbon fluxes this century. Abrupt thaw lake emissions are similar under moderate and high representative concentration pathways (RCP4.5 and RCP8.5), but their relative contribution to the PCF is much larger under the moderate warming scenario. Abrupt thaw accelerates mobilization of deeply frozen, ancient carbon, increasing 14C-depleted permafrost soil carbon emissions by ~125-190% compared to gradual thaw alone. These findings demonstrate the need to incorporate abrupt thaw processes in earth system models for more comprehensive projection of the PCF this century.
25-hydroxyvitamin D (25[OH]D) deficiency is associated with compromised bone mineralisation, fatigue, suppressed immune function and unsatisfactory skeletal muscle recovery. We investigated the risk of 25(OH)D insufficiency or deficiency in endurance athletes compared to sedentary non-athletes living at 64° north.
University student-athletes (TS) and sedentary students (SS) volunteered to participate in this study. TS engaged in regular exercise while SS exercised no more than 20 minutes/week. Metabolic Equivalent of Task (MET) scores for participants were determined. Vitamin D intake was assessed using the National Cancer Institute's 24-hour food recall (ASA24). Fasting plasma 25(OH)D levels were quantified via enzyme-linked immunosorbent assay.
TS reported higher activity levels than SS as assessed with MET-minutes/week and ranking of physical activity levels (p
Cites: Chem Biol. 2014 Mar 20;21(3):319-29 PMID 24529992
The aim of this study was to examine the effects of genetic and environment influences and sex on injury involvement using two sets of Finnish twin data. The younger participants were 955 twins born between 1983 and 1987, aged 20 to 24 years. The older participants were 12,428 twins born between 1930 and 1957, aged 33 to 60 years. Within-twin correlations in monozygotic and dizygotic twins suggested that genetic effects play no role in injury involvement among young twins, but do have some effect at older ages. The results indicated that environmental factors have greater importance in injury involvement than genetic factors in the younger twin data set (FT12), whereas in a middle-aged (33-60 years) twin data set, genetic effects explained about quarter of the variance in injury involvement. Sex was a strong contributing factor, with males being generally more prone to injuries than females.
Experiencing a stillbirth can be a potent stressor for psychological distress in the subsequent pregnancy and possibly after the subsequent birth. The impact on women's relationship with her partner in the subsequent pregnancy and postpartum remains uncertain. The objectives of the study were 1) To investigate the prevalence of anxiety and depression in the pregnancy following stillbirth and assess gestational age at stillbirth and inter-pregnancy interval as individual risk factors. 2) To assess the course of anxiety, depression and satisfaction with partner relationship up to 3 years after the birth of a live-born baby following stillbirth.
This study is based on data from the Norwegian Mother and Child Cohort Study, a population-based pregnancy cohort. The sample included 901 pregnant women: 174 pregnant after a stillbirth, 362 pregnant after a live birth and 365 previously nulliparous. Anxiety and depression were assessed by short-form subscales of the Hopkins Symptoms Checklist, and relationship satisfaction was assessed by the Relationship Satisfaction Scale. These outcomes were measured in the third trimester of pregnancy and 6, 18 and 36 months postpartum. Logistic regression models were applied to study the impact of previous stillbirth on depression and anxiety in the third trimester of the subsequent pregnancy and to investigate gestational age and inter-pregnancy interval as potential risk factors.
Women pregnant after stillbirth had a higher prevalence of anxiety (22.5%) and depression (19.7%) compared with women with a previous live birth (adjusted odds ratio (aOR) 5.47, 95% confidence interval (CI) 2.90-10.32 and aOR 1.91, 95% CI 1.11-3.27) and previously nulliparous women (aOR 4.97, 95% CI 2.68-9.24 and aOR 1.91, 95% CI 1.08-3.36). Gestational age at stillbirth (>?30 weeks) and inter-pregnancy interval?
Warming in the Arctic has been much faster than the rest of the world in both observations and model simulations, a phenomenon known as the Arctic amplification (AA) whose cause is still under debate. By analyzing data and model simulations, here we show that large AA occurs only from October to April and only over areas with significant sea-ice loss. AA largely disappears when Arctic sea ice is fixed or melts away. Periods with larger AA are associated with larger sea-ice loss, and models with bigger sea-ice loss produce larger AA. Increased outgoing longwave radiation and heat fluxes from the newly opened waters cause AA, whereas all other processes can only indirectly contribute to AA by melting sea-ice. We conclude that sea-ice loss is necessary for the existence of large AA and that models need to simulate Arctic sea ice realistically in order to correctly simulate Arctic warming under increasing CO2.
Cerebral ischemia-reperfusion (I/R) injury initiates a cascade of events, generating nitric oxide (NO) and superoxide(O2•-) to form peroxynitrite (ONOO-), a potent oxidant. Arctic ground squirrels (AGS; Urocitellus parryii) show high tolerance to I/R injury. However, the underlying mechanism remains elusive. We hypothesize that tolerance to I/R modeled in an acute hippocampal slice preparation in AGS is modulated by reduced oxidative and nitrative stress. Hippocampal slices (400µm) from rat and AGS were subjected to oxygen glucose deprivation (OGD) using a novel microperfusion technique. Slices were exposed to NO, O2.- donors with and without OGD; pretreatment with inhibitors of NO, O2.- and ONOO- followed by OGD. Perfusates collected every 15min were analyzed for LDH release, a marker of cell death. 3-nitrotyrosine (3NT) and 4-hydroxynonenal (4HNE) were measured to assess oxidative and nitrative stress. Results show that NO/O2.- alone is not sufficient to cause ischemic-like cell death, but with OGD enhances cell death more in rat than in AGS. A NOS inhibitor, SOD mimetic and ONOO- inhibitor attenuates OGD injury in rat but has no effect in AGS. Rats also show a higher level of 3NT and 4HNE with OGD than AGS suggesting the greater level of injury in rat is via formation of ONOO-.
Cites: Free Radic Res Commun. 1993;18(4):195-9 PMID 8396550
Postpartum depression (PPD) reportedly affects between 6.5-19% of all new mothers. Identifying those at greatest risk for PPD has implications for prevention, early detection and intervention. While the relationship between extremes of body mass index (BMI) and depression has been frequently studied, the association between BMI and PPD is less understood.
Prospective cohort of all women with live singleton births in Sweden 1997-2008. We calculated the relative risk (RR) for PPD in relation to each woman's BMI and depression history. PPD diagnosis was based on a clinical diagnosis of depression within the first postpartum year.
First trimester BMI measurements were available for 611,506 women. Low BMI (?35) RRadj?=?1.23, [95% CI: 1.04-1.45] were associated with increased PPD risk. Women with a depression history had an increased risk with low BMI (RRadj?=?1.51, [95% CI: 1.17-1.95]).
Only first births were analyzed, potentially underestimating PPD incidence. Clinical data from health registries offers limited resolution regarding the specificity of diagnoses and incomplete sensitivity if women do not seek care.
First trimester of pregnancy BMI is associated with PPD risk. This risk is further modified by depression history. While low BMI places all women at risk for PPD, being overweight increases risk of PPD only in women without a history of depression. Future research should explore potentially modifiable mechanisms involved in the relationship between PPD and BMI and should also examine interventional strategies for pregnant women at the extremes of BMI and/or with a depression history.
The traditional lifestyle of Yup'ik Alaska Native people, including a diet abundant in marine-based foods and physical activity, may be cardio-protective. However, iq'mik, a traditional form of smokeless tobacco used by >50% of Yup'ik adults, could increase cardiometabolic (CM) risk. Our objective was to characterize the associations between iq'mik use and biomarkers of CM status (low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C], triglycerides [TG], systolic blood pressure [SBP] and diastolic blood pressure [DBP], glycated hemoglobin [HbA1c], fasting blood glucose [FBG], waist circumference [WC], and body mass index [BMI]).
We assessed these associations using data from a cross-sectional sample of Yup'ik adults (n?=?874). Current iq'mik use, demographic, and lifestyle data were collected through interviews. Fasting blood samples were collected to measure LDL-C, HDL-C, TG, HbA1c, and FBG. SBP, DBP, WC, and BMI were obtained by physical examination. We characterized the association between current iq'mik use and continuous biomarkers of CM status using multiple approaches, including adjustment for measures of Yup'ik lifestyle and a propensity score.
Based on either adjustment method, current iq'mik use was significantly and positively associated with at least 5% higher HDL-C, and significantly associated but in an inverse direction with multiple biomarkers of CM status including 7% lower TG, 0.05% lower HbA1c, 2% lower FBG, 4% lower WC, and 4% lower BMI. Observed associations for LDL-C, SBP, and DBP varied by adjustment method.
This inverse association between iq'mik use and cardiometabolic risk status has not been previously reported. Additional research is needed to replicate these findings and explore physiological mechanisms and/or confounding factors.
Belief in an American Indian/Alaska Native (AI/AN) specific biological vulnerability (BV) to alcohol problems (aka the "firewater myth") is associated with worse alcohol outcomes among AI/AN college students who drink, despite also being associated with greater attempts to reduce drinking. The current study examined how belief in a BV may have affected how 157 AI/AN college students who drink (a) attempted to moderate their alcohol use and avoid alcohol-related problems using abstinence-based and harm reduction strategies, and (b) attitudes toward these strategies as a means of addressing alcohol problems. Contrary to our hypotheses, belief in a BV was not found to be associated with use of harm reduction strategies or with how effective students believed these strategies to be. However, greater belief in a BV was associated with lower self-efficacy for the use of harm reduction strategies among more frequent heavy episodic drinkers. This is concerning, as the use of harm reduction strategies was associated with less frequent heavy episodic drinking in this sample. In contrast, belief in a BV was positively associated with the use of abstinence-based strategies and with how effective these strategies were perceived to be. However, for individuals with average or greater belief in a BV, abstinence-based strategies were associated with greater alcohol consequences. The results suggest that for AI/AN students who drink, belief in a BV may be influencing the strategies used to moderate alcohol use and avoid alcohol-related harm, as well as attitudes toward these strategies, in ways that do not appear helpful. (PsycINFO Database Record