Low carbohydrate diets, which restrict carbohydrate in favour of increased protein or fat intake, or both, are a popular weight-loss strategy. However, the long-term effect of carbohydrate ...restriction on mortality is controversial and could depend on whether dietary carbohydrate is replaced by plant-based or animal-based fat and protein. We aimed to investigate the association between carbohydrate intake and mortality.
We studied 15 428 adults aged 45–64 years, in four US communities, who completed a dietary questionnaire at enrolment in the Atherosclerosis Risk in Communities (ARIC) study (between 1987 and 1989), and who did not report extreme caloric intake (<600 kcal or >4200 kcal per day for men and <500 kcal or >3600 kcal per day for women). The primary outcome was all-cause mortality. We investigated the association between the percentage of energy from carbohydrate intake and all-cause mortality, accounting for possible non-linear relationships in this cohort. We further examined this association, combining ARIC data with data for carbohydrate intake reported from seven multinational prospective studies in a meta-analysis. Finally, we assessed whether the substitution of animal or plant sources of fat and protein for carbohydrate affected mortality.
During a median follow-up of 25 years there were 6283 deaths in the ARIC cohort, and there were 40 181 deaths across all cohort studies. In the ARIC cohort, after multivariable adjustment, there was a U-shaped association between the percentage of energy consumed from carbohydrate (mean 48·9%, SD 9·4) and mortality: a percentage of 50–55% energy from carbohydrate was associated with the lowest risk of mortality. In the meta-analysis of all cohorts (432 179 participants), both low carbohydrate consumption (<40%) and high carbohydrate consumption (>70%) conferred greater mortality risk than did moderate intake, which was consistent with a U-shaped association (pooled hazard ratio 1·20, 95% CI 1·09–1·32 for low carbohydrate consumption; 1·23, 1·11–1·36 for high carbohydrate consumption). However, results varied by the source of macronutrients: mortality increased when carbohydrates were exchanged for animal-derived fat or protein (1·18, 1·08–1·29) and mortality decreased when the substitutions were plant-based (0·82, 0·78–0·87).
Both high and low percentages of carbohydrate diets were associated with increased mortality, with minimal risk observed at 50–55% carbohydrate intake. Low carbohydrate dietary patterns favouring animal-derived protein and fat sources, from sources such as lamb, beef, pork, and chicken, were associated with higher mortality, whereas those that favoured plant-derived protein and fat intake, from sources such as vegetables, nuts, peanut butter, and whole-grain breads, were associated with lower mortality, suggesting that the source of food notably modifies the association between carbohydrate intake and mortality.
National Institutes of Health.
Although genetic risk scores have been used to predict hypertension, their utility in the clinical setting remains uncertain. Our study comprised N=218 792 FinnGen participants (mean age 58 years, ...56% women) and N=22 624 well-phenotyped FINRISK participants (mean age 50 years, 53% women). We used public genome-wide association data to compute polygenic risk scores (PRSs) for systolic and diastolic blood pressure (BP). Using time-to-event analysis, we then assessed (1) the association of BP PRSs with hypertension and cardiovascular disease (CVD) in FinnGen and (2) the improvement in model discrimination when combining BP PRSs with the validated 4- and 10-year clinical risk scores for hypertension and CVD in FINRISK. In FinnGen, compared with having a 20 to 80 percentile range PRS, a PRS in the highest 2.5% conferred 2.3-fold (95% CI, 2.2–2.4) risk of hypertension and 10.6 years (95% CI, 9.9–11.4) earlier hypertension onset. In subgroup analyses, this risk was only 1.6-fold (95% CI, 1.5–1.7) for late-onset hypertension (age ≥55 years) but 2.8-fold (95% CI, 2.6–2.9) for early-onset hypertension (age <55 years). Elevated systolic BP PRS also conferred 1.3-fold (95% CI, 1.2–1.4) risk of CVD and 2.3 years (95% CI, 1.6–3.1) earlier onset. In FINRISK, systolic and diastolic BP PRSs improved clinical risk prediction of hypertension (but not CVD), increasing the C statistics by 0.7% (95% CI, 0.3–1.1). We demonstrate that genetic information improves hypertension risk prediction. BP PRSs together with traditional risk factors could improve prediction of hypertension and particularly early-onset hypertension, which confers substantial CVD risk.
The carbon storage potential of terrestrial ecosystems depends in part on how atmospheric conditions influence the type and amount of surface radiation available for photosynthesis. Diffuse light, ...resulting from interactions between incident solar radiation and atmospheric aerosols and clouds, has been postulated to increase carbon uptake in terrestrial ecosystems. However, the magnitude of the diffuse light effect is unclear because existing studies use different methods to derive above-canopy diffuse light conditions. We used site-based, above-canopy measurements of diffuse light and gross primary productivity (GPP) from 10 temperate ecosystems (including mixed conifer forests, deciduous broadleaf forests, and croplands) to quantify the GPP variation explained by diffuse photosynthetically active radiation (PAR) and to calculate increases in GPP as a function of diffuse light. Our analyses show that diffuse PAR explained up to 41% of variation in GPP in croplands and up to 17% in forests, independent of direct light levels. Carbon enhancement rates in response to diffuse PAR (calculated after accounting for vapor pressure deficit and air temperature) were also higher in croplands (0.011-0.050 mu mol CO2 per mu mol photons of diffuse PAR) than in forests (0.003-0.018 mu mol CO2 per mu mol photons of diffuse PAR). The amount of variation in GPP and carbon enhancement rate both differed with solar zenith angle and across sites for the same plant functional type. At crop sites, diffuse PAR had the strongest influence and the largest carbon enhancement rate during early mornings and late afternoons when zenith angles were large, with greater enhancement in the afternoons. In forests, diffuse PAR had the strongest influence at small zenith angles, but the largest carbon enhancement rate at large zenith angles, with a trend in ecosystem-specific responses. These results highlight the influence of zenith angle and the role of plant community composition in modifying diffuse light enhancement in terrestrial ecosystems, which will be important in scaling this effect from individual sites to the globe.
How I'm standing up for science Cheng, Susan J
Science (American Association for the Advancement of Science),
02/2017, Letnik:
355, Številka:
6327
Journal Article
The extent to which select vascular risk factors differentially influence blood pressure (BP) is incompletely understood. Thus, we used multilevel modeling to analyze serial BP measurements using 21 ...732 person-observations obtained on Framingham Heart Study participants (mean age, 38 years, 52% women; 4993 unique individuals) over a 28-year period. We related longitudinal tracking of each BP measure (systolic BP, diastolic BP, mean arterial pressure, and pulse pressure) to age, sex, body mass index, smoking, diabetes mellitus, total/high-density lipoprotein cholesterol ratio, and heart rate. In multivariable-adjusted analyses, we observed that older age, male sex, greater body mass index, and higher heart rate were positively associated with increase in all BP measures (P<0.0001). Notably, higher total/high-density lipoprotein cholesterol ratio was associated with greater mean arterial pressure (P<0.01). Conversely, diabetes mellitus and smoking were associated with higher pulse pressure (P<0.01). We also observed effect modification by sexthe increase in pulse pressure with age and body mass index was more pronounced in women compared with men (P<0.0001). All BP measures tracked at higher levels in both men and women with multiple vascular risk factors. Taken together, our longitudinal observations in a large community-based sample demonstrate a greater pulsatile load in women than in men with increasing age. We also observed a differential impact of select vascular risk factors on the individual components of BP, underscoring distinct regulation of these measures over the life course.
If we assume that women and men exhibit variations of the same fundamental vascular physiology, then conventional analyses of subclinical measures would suggest that women catch up to men by midlife ...in the extent of potentially important vascular disease. Alternatively, under the assumption that vascular physiology may fundamentally differ between women and men, a sex-specific analysis of existing data could offer new insights and augment our understanding of sex differences in cardiovascular diseases.
To evaluate whether longitudinal patterns of blood pressure (BP) elevation differ between women and men during the life course when considering baseline BP levels as the reference.
We conducted sex-specific analyses of longitudinal BP measures (144 599 observations) collected for a period of 43 years (1971 to 2014) in 4 community-based US cohort studies. The combined total included 32 833 participants (54% female) spanning ages 5 to 98 years. Data were analyzed between May 4, 2019, and August 5, 2019.
Age and serially assessed longitudinal BP measures: systolic BP, diastolic BP, mean arterial pressure (MAP), and pulse pressure (PP).
Sex-specific change in each primary BP measure compared with baseline BP levels, derived from multilevel longitudinal models fitted over the age span, and new-onset cardiovascular disease events.
Of the 32 833 participants, 17 733 were women (54%). Women compared with men exhibited a steeper increase in BP that began as early as in the third decade and continued through the life course (likelihood ratio test χ2 = 531 for systolic BP; χ2 = 123 for diastolic BP; χ2 = 325 for MAP; and χ2 = 572 for PP; P for all <.001). After adjustment for multiple cardiovascular disease risk factors, these between-sex differences in all BP trajectories persisted (likelihood ratio test χ2 = 314 for systolic BP; χ2 = 31 for diastolic BP; χ2 = 129 for MAP; and χ2 = 485 for PP; P for all <.001).
In contrast with the notion that important vascular disease processes in women lag behind men by 10 to 20 years, sex-specific analyses indicate that BP measures actually progress more rapidly in women than in men, beginning early in life. This early-onset sexual dimorphism may set the stage for later-life cardiovascular diseases that tend to present differently, not simply later, in women compared with men.
Pulmonary congestion is a common and important finding in heart failure (HF). While clinical examination and chest radiography are insensitive, lung ultrasound (LUS) is a novel technique that may ...detect and quantify subclinical pulmonary congestion. We sought to independently relate LUS and clinical findings to 6-month HF hospitalizations and all-cause mortality (composite primary outcome).
We used LUS to examine 195 NYHA class II-IV HF patients (median age 66, 61% men, 74% white, ejection fraction 34%) during routine cardiology outpatient visits. Lung ultrasound was performed in eight chest zones with a pocket ultrasound device (median exam duration 2 min) and analysed offline.
In 185 patients with adequate LUS images in all zones, the sum of B-lines (vertical lines on LUS) ranged from 0 to 13. B-lines, analysed by tertiles, were associated with clinical and laboratory markers of congestion. Thirty-two per cent of patients demonstrated ≥3 B-lines on LUS, yet 81% of these patients had no findings on auscultation. During the follow-up period, 50 patients (27%) were hospitalized for HF or died. Patients in the third tertile (≥3 B-lines) had a four-fold higher risk of the primary outcome (adjusted HR 4.08, 95% confidence interval, CI 1.95, 8.54; P < 0.001) compared with those in the first tertile and spent a significantly lower number of days alive and out of the hospital (125 days vs. 165 days; adjusted P < 0.001).
Pulmonary congestion assessed by ultrasound is prevalent in ambulatory patients with chronic HF, is associated with other features of clinical congestion, and identifies those who have worse prognosis.
What is known and objective
Thyrotoxic periodic paralysis (TPP) with hypokalaemia is a rare acute phenomenon. Reports of the use of high‐dose non‐selective β‐blockers describe symptom resolution, but ...often administration does not occur promptly enough in the treatment course and patients may experience overcorrection and hyperkalaemia.
Case description
A 37‐year‐old Hispanic male developed TPP. Patient was successfully treated with low‐dose oral propranolol and potassium supplementation with no overcorrection.
What is new and conclusion
Delay in the administration of non‐selective β‐blockers may lead to overcorrection of potassium with exogenous supplementation. Low‐dose propranolol administered in the Emergency Department was successful in preventing overcorrection of potassium.
Low‐dose oral propranolol was administered in the Emergency Department for management of a patient with thyrotoxic periodic paralysis (TPP). Hypokalaemia was corrected with no overcorrection.
Emerging technologies allow the high-throughput profiling of metabolic status from a blood specimen (metabolomics). We investigated whether metabolite profiles could predict the development of ...diabetes. Among 2,422 normoglycemic individuals followed for 12 years, 201 developed diabetes. Amino acids, amines and other polar metabolites were profiled in baseline specimens by liquid chromatography-tandem mass spectrometry (LC-MS). Cases and controls were matched for age, body mass index and fasting glucose. Five branched-chain and aromatic amino acids had highly significant associations with future diabetes: isoleucine, leucine, valine, tyrosine and phenylalanine. A combination of three amino acids predicted future diabetes (with a more than fivefold higher risk for individuals in top quartile). The results were replicated in an independent, prospective cohort. These findings underscore the potential key role of amino acid metabolism early in the pathogenesis of diabetes and suggest that amino acid profiles could aid in diabetes risk assessment.
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