Hopping Hotspots: Global Shifts in Marine Biodiversity Renema, W.; Bellwood, D. R.; Braga, J. C. ...
Science (American Association for the Advancement of Science),
08/2008, Letnik:
321, Številka:
5889
Journal Article
Recenzirano
Hotspots of high species diversity are a prominent feature of modern global biodiversity patterns. Fossil and molecular evidence is starting to reveal the history of these hotspots. There have been ...at least three marine biodiversity hotspots during the past 50 million years. They have moved across almost half the globe, with their timing and locations coinciding with major tectonic events. The birth and death of successive hotspots highlights the link between environmental change and biodiversity patterns. The antiquity of the taxa in the modern Indo-Australian Archipelago hotspot emphasizes the role of pre-Pleistocene events in shaping modern diversity patterns.
Aims/hypothesis
Weight reduction is fundamental for type 2 diabetes management and remission, but uncertainty exists over which diet type is best to achieve and maintain weight loss. We evaluated ...dietary approaches for weight loss, and remission, in people with type 2 diabetes to inform practice and clinical guidelines.
Methods
First, we conducted a systematic review of published meta-analyses of RCTs of weight-loss diets. We searched MEDLINE (Ovid), PubMed, Web of Science and Cochrane Database of Systematic Reviews, up to 7 May 2021. We synthesised weight loss findings stratified by diet types and assessed meta-analyses quality with A Measurement Tool to Assess Systematic Reviews (AMSTAR) 2. We assessed certainty of pooled results of each meta-analysis using Grading of Recommendations, Assessment, Development and Evaluations (GRADE) (PROSPERO CRD42020169258). Second, we conducted a systematic review of any intervention studies reporting type 2 diabetes remission with weight-loss diets, in MEDLINE (via PubMed), Embase and Cochrane Central Register of Controlled Trials, up to 10 May 2021. Findings were synthesised by diet type and study quality (Cochrane Risk of Bias tool 2.0 and Risk Of Bias In Non-randomised Studies – of Interventions ROBINS-I), with GRADE applied (PROSPERO CRD42020208878).
Results
We identified 19 meta-analyses of weight-loss diets, involving 2–23 primary trials (
n
= 100–1587), published 2013–2021. Twelve were ‘critically low’ or ‘low’ AMSTAR 2 quality, with seven ‘high’ quality. Greatest weight loss was reported with very low energy diets, 1.7–2.1 MJ/day (400–500 kcal) for 8–12 weeks (high-quality meta-analysis, GRADE low), achieving 6.6 kg (95% CI −9.5, −3.7) greater weight loss than low-energy diets (4.2–6.3 MJ/day 1000–1500 kcal). Formula meal replacements (high quality, GRADE moderate) achieved 2.4 kg (95% CI −3.3, −1.4) greater weight loss over 12–52 weeks. Low-carbohydrate diets were no better for weight loss than higher-carbohydrate/low-fat diets (high quality, GRADE high). High-protein, Mediterranean, high-monounsaturated-fatty-acid, vegetarian and low-glycaemic-index diets all achieved minimal (0.3–2 kg) or no difference from control diets (low to critically low quality, GRADE very low/moderate). For type 2 diabetes remission, of 373 records, 16 met inclusion criteria. Remissions at 1 year were reported for a median 54% of participants in RCTs including initial low-energy total diet replacement (low-risk-of-bias study, GRADE high), and 11% and 15% for meal replacements and Mediterranean diets, respectively (some concerns for risk of bias in studies, GRADE moderate/low). For ketogenic/very low-carbohydrate and very low-energy food-based diets, the evidence for remission (20% and 22%, respectively) has serious and critical risk of bias, and GRADE certainty is very low.
Conclusions/interpretation
Published meta-analyses of hypocaloric diets for weight management in people with type 2 diabetes do not support any particular macronutrient profile or style over others. Very low energy diets and formula meal replacement appear the most effective approaches, generally providing less energy than self-administered food-based diets. Programmes including a hypocaloric formula ‘total diet replacement’ induction phase were most effective for type 2 diabetes remission. Most of the evidence is restricted to 1 year or less. Well-conducted research is needed to assess longer-term impacts on weight, glycaemic control, clinical outcomes and diabetes complications.
Graphical abstract
We report cosmic microwave background (CMB) power-spectrum measurements from the first 100 deg{sup 2} field observed by the South Pole Telescope (SPT) at 150 and 220 GHz. On angular scales where the ...primary CMB anisotropy is dominant, l {approx}< 3000, the SPT power spectrum is consistent with the standard {Lambda}CDM cosmology. On smaller scales, we see strong evidence for a point-source contribution, consistent with a population of dusty, star-forming galaxies. After we mask bright point sources, anisotropy power on angular scales of 3000 < l < 9500 is detected with a signal-to-noise ratio {approx}>50 at both frequencies. We combine the 150 and 220 GHz data to remove the majority of the point-source power and use the point-source-subtracted spectrum to detect Sunyaev-Zel'dovich (SZ) power at 2.6{sigma}. At l = 3000, the SZ power in the subtracted bandpowers is 4.2 {+-} 1.5 {mu}K{sup 2}, which is significantly lower than the power predicted by a fiducial model using WMAP5 cosmological parameters. This discrepancy may suggest that contemporary galaxy cluster models overestimate the thermal pressure of intracluster gas. Alternatively, this result can be interpreted as evidence for lower values of {sigma}{sub 8}. When combined with an estimate of the kinetic SZ contribution, the measured SZ amplitude shifts {sigma}{sub 8} from the primary CMB anisotropy derived constraint of 0.794 {+-} 0.028 down to 0.773 {+-} 0.025. The uncertainty in the constraint on {sigma}{sub 8} from this analysis is dominated by uncertainties in the theoretical modeling required to predict the amplitude of the SZ power spectrum for a given set of cosmological parameters.
We use data from the first 100 deg{sup 2} field observed by the South Pole Telescope (SPT) in 2008 to measure the angular power spectrum of temperature anisotropies contributed by the background of ...dusty star-forming galaxies (DSFGs) at millimeter wavelengths. From the auto- and cross-correlation of 150 and 220 GHz SPT maps, we significantly detect both Poisson distributed and, for the first time at millimeter wavelengths, clustered components of power from a background of DSFGs. The spectral indices of the Poisson and clustered components are found to be {alpha}-bar{sup P}{sub 150-220}=3.86{+-}0.23 and {alpha} {sup C}{sub 150-220} = 3.8 {+-} 1.3, implying a steep scaling of the dust emissivity index {beta} {approx} 2. The Poisson and clustered power detected in SPT, BLAST (at 600, 860, and 1200 GHz), and Spitzer (1900 GHz) data can be understood in the context of a simple model in which all galaxies have the same graybody spectrum with dust emissivity index of {beta} = 2 and dust temperature T{sub d} = 34 K. In this model, half of the 150 GHz background light comes from redshifts greater than 3.2. We also use the SPT data to place an upper limit on the amplitude of the kinetic Sunyaev-Zel'dovich power spectrum at l = 3000 of 13 {mu}K{sup 2} at 95% confidence.
BACKGROUND
Obesity-induced hypertension appears to be due, in part, to increased renal sympathetic activity. Catheter-based renal denervation (RD) has been reported to lower arterial blood pressure ...(BP) in humans with resistant hypertension, many of whom are obese. This study was performed to assess the impact of radiofrequency-induced RD on renal function, BP, renal norepinephrine (NE), and histology of nerves along the renal artery in obese, hypertensive dogs, an experimental model that closely mimics cardiorenal and metabolic changes in obese hypertensive humans.
METHODS
After control measurements of cardiovascular and renal function were obtained in obese dogs fed a high-fat diet, bilateral RD was performed using the St. Jude Medical EnligHTN RD system. After RD, BP was measured continuously for 8 weeks, and glomerular filtration rate (GFR) was measured biweekly for 6 weeks. At the end of the study, renal arteries were collected for histological analysis, and kidneys were obtained for NE measurement.
RESULTS
Eight weeks after RD, systolic BP fell from 157±5mm Hg pre-RD to 133±3mm Hg (P < 0.01), and mean arterial pressure decreased by 9mm Hg compared with pre-RD (P < 0.01). There were no significant changes in GFR. Renal nerve injury was most prevalent 0.28-3.5mm from the renal artery lumen. RD caused injury in 46% of the renal nerves observed and reduced renal tissue NE by 42% (P < 0.01).
CONCLUSIONS
Catheter-based RD with the St. Jude Medical EnligHTN system lowers BP in obese dogs without significantly compromising renal function.
Stream ecosystem processes such as nutrient cycling may vary with stream position in the network. Using a scaling approach, we examined the relationship between stream size and nutrient uptake ...length, which represents the mean distance that a dissolved solute travels prior to removal from the water column. Ammonium (NH4+) uptake length increased proportionally with stream size measured as specific discharge (discharge/stream width) with a scaling exponent = 1.01. In contrast, uptake lengths for nitrate (NO3−) and soluble reactive phosphorus (SRP) increased more rapidly than increases in specific discharge (scaling exponents = 1.19 for NO3− and 1.35 for SRP). Additionally, the ratio of inorganic nitrogen (N) uptake length to SRP uptake length declined with stream size; there was relatively lower demand for SRP compared to N as stream size increased. Finally, we related the scaling of uptake length with specific discharge to that of stream length using Hack's law and downstream hydraulic geometry. Ammonium uptake length increased less than proportionally with distance from the headwaters, suggesting a strong role for larger streams and rivers in regulating nutrient transport.
ABSTRACT
We present Sunyaev–Zel'dovich (SZ) measurements of 15 massive X-ray-selected galaxy clusters obtained with the South Pole Telescope (SPT). The SZ cluster signals are measured at 150 GHz, and ...concurrent 220 GHz data are used to reduce astrophysical contamination. Radial profiles are computed using a technique that takes into account the effects of the beams and filtering. In several clusters, significant SZ decrements are detected out to a substantial fraction of the virial radius. The profiles are fit to the β-model and to a generalized Navarro–Frenk–White (NFW) pressure profile, and are scaled and stacked to probe their average behavior. We find model parameters that are consistent with previous studies: β = 0.86 and
r
core
/
r
500
= 0.20 for the β-model, and (α
n
, β
n
, γ
n
,
c
500
) = (1.0, 5.5, 0.5, 1.0) for the generalized NFW model. Both models fit the SPT data comparably well, and both are consistent with the average SZ profile out to beyond
r
500
. The integrated Compton-
y
parameter
Y
SZ
is computed for each cluster using both model-dependent and model-independent techniques, and the results are compared to X-ray estimates of cluster parameters. We find that
Y
SZ
scales with
Y
X
and gas mass with low scatter. Since these observables have been found to scale with total mass, our results point to a tight mass–observable relation for the SPT cluster survey.
Endocrine disrupting chemicals are widely distributed in our environment. Humans are exposed to these compounds not only through their occupations, but also through dietary consumption and exposure ...to contaminated water, personal care products and textiles. Chemicals that are persistent in the body and in our environment include dioxins and polychlorinated biphenyls. Non-persistent chemicals including bisphenol A, phthalates and parabens are equally as important because they are ubiquitous in our environment. Heavy metals, including lead and cadmium, can also have endocrine disrupting properties. Although difficult to study due to their variety of sources of exposures and mechanisms of action, these chemicals have been associated with early menopause, increased frequency of vasomotor symptoms, altered steroid hormone levels and markers of diminished ovarian reserve. Understanding the impacts of these exposures is important given the potential for epigenetic modification, which can alter gene function and result in multi-generational effects. This review summarizes findings in humans and animals or cell-based models from the past decade of research. Continued research is needed to assess the effects of mixtures of chemicals, chronic exposures and new compounds that are continuously being developed as replacements for toxic chemicals that are being phased out.
Lotic ecosystems are made up of numerous tributary streams forming a complex branching network. The point where smaller tributaries flow into larger rivers, or tributary junctions, may be sites in ...the network where spatial discontinuities or "hot spots" are created and maintained, because small streams funnel important materials captured from the surrounding landscape and carry them by gravity downstream. We hypothesized that habitat complexity, environmental productivity, and abundance of primary consumers and predators peak in mainstem rivers at or downstream of tributary junctions. We conducted surveys in three river basins and 13 reaches to examine interdependence between tributary streams and the larger rivers they enter. Wood abundance and volume, variability in median substrate size (i.e., substrate heterogeneity), concentrations of nitrogen and phosphorus in water, algal biomass, and abundance of consumers and predators peaked with a higher frequency at or downstream of tributary junctions. For several variables, the size of the tributary relative to the main stem contributed to the strength of tributary affect. These findings suggest that some tributary streams have fundamental effects on the larger rivers they enter. We argue that maintaining the integrity of connections among and between ecosystems is essential for promoting habitat complexity and community structure within river networks.
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