Summary
Imbalances in the gut microbiota, the bacteria that inhabit the intestines, are central to the pathogenesis of obesity. This systematic review assesses the association between the gut ...microbiota and weight loss in overweight/obese adults and its potential manipulation as a target for treating obesity. This review identified 43 studies using the keywords ‘overweight’ or ‘obesity’ and ‘microbiota’ and related terms; among these studies, 17 used dietary interventions, 11 used bariatric surgery and 15 used microbiota manipulation. The studies differed in their methodologies as well as their intervention lengths. Restrictive diets decreased the microbiota abundance, correlated with nutrient deficiency rather than weight loss and generally reduced the butyrate producers Firmicutes, Lactobacillus sp. and Bifidobacterium sp. The impact of surgical intervention depended on the given technique and showed a similar effect on butyrate producers, in addition to increasing the presence of the Proteobacteria phylum, which is related to changes in the intestinal absorptive surface, pH and digestion time. Probiotics differed in strain and duration with diverse effects on the microbiota, and they tended to reduce body fat. Prebiotics had a bifidogenic effect and increased butyrate producers, likely due to cross‐feeding interactions, contributing to the gut barrier and improving metabolic outcomes. All of the interventions under consideration had impacts on the gut microbiota, although they did not always correlate with weight loss. These results show that restrictive diets and bariatric surgery reduce microbial abundance and promote changes in microbial composition that could have long‐term detrimental effects on the colon. In contrast, prebiotics might restore a healthy microbiome and reduce body fat.
The binary neutron star merger event GW170817 was detected through both electromagnetic radiation and gravitational waves. Its afterglow emission may have been produced by either a narrow ...relativistic jet or an isotropic outflow. High-spatial-resolution measurements of the source size and displacement can discriminate between these scenarios. We present very-long-baseline interferometry observations, performed 207.4 days after the merger by using a global network of 32 radio telescopes. The apparent source size is constrained to be smaller than 2.5 milli-arc seconds at the 90% confidence level. This excludes the isotropic outflow scenario, which would have produced a larger apparent size, indicating that GW170817 produced a structured relativistic jet. Our rate calculations show that at least 10% of neutron star mergers produce such a jet.
Knowledge of the shape of the mass spectrum of compact objects can be used to help break the degeneracy between the mass and redshift of the gravitational wave (GW) sources and thus can be used to ...infer cosmological parameters in the absence of redshift measurements obtained from electromagnetic observations. In this paper, we study extensively different aspects of this approach, including its computational limits and achievable accuracy. Focusing on ground-based detectors with current and future sensitivities, we first perform the analysis of an extensive set of simulated data using a hierarchical Bayesian scheme that jointly fits the source population and cosmological parameters. We consider a population model (power-law plus Gaussian) which exhibits characteristic scales (extremes of the mass spectrum, presence of an accumulation point modeled by a Gaussian peak) that allow an indirect estimate of the source redshift. Our analysis of this catalog highlights and quantifies the tight interplay between source population and cosmological parameters, as well as the influence of initial assumptions (whether formulated on the source or cosmological parameters). We then validate our results by an "end-to-end" analysis using simulated GW h (t) data and posterior samples generated from Bayesian samplers used for GW parameter estimation, thus mirroring the analysis chain used for observational data for the first time in literature. Our results then lead us to re-examine the estimation of H0 obtained with GWTC-1 in Abbott et al. LIGO Scientific, Virgo Collaborations, Astrophys. J. 909, 218 (2021), and we show explicitly how population assumptions impact the final H0 result. Together, our results underline the importance of inferring source population and cosmological parameters simultaneously (and not separately as is often assumed). The only exception, as we discuss, is if an electromagnetic counterpart was to be observed for all the BBH events; then, the population assumptions have less impact on the estimation of cosmological parameters.
Background
Although bariatric surgery has been shown to improve hepatic steatosis in morbidly obese patients, the effect of weight loss on hepatic fibrosis has not been determined. Since the ...prognosis of patients with nonalcoholic fatty liver disease is closely related to the development of hepatic fibrosis, it is important to determine the hepatic histology of these patients after weight loss. We therefore evaluated the prevalence of hepatic fibrosis in morbidly obese patients undergoing bariatric surgery and assessed the correlation of histologic changes with weight loss.
Methods
We retrospectively evaluated 78 morbidly obese patients who underwent gastric bypass. Liver biopsies were taken during surgery and after weight loss, and the correlations between histologic findings and hepatic fibrosis were determined.
Results
Of the 78 patients, 35 (44.8%) had fibrosis at first biopsy, and 24 (30.8%) had hepatic fibrosis after weight loss, including 19 of the 35 patients (54.3%) with fibrosis at first biopsy and 5 of the 43 (11.6%) without hepatic fibrosis at first biopsy (
P
= 0.027).
Conclusions
Weight loss in morbidly obese patients was associated with a reduction in the prevalence of hepatic fibrosis.
Abstract
Gravitational wave (GW) standard sirens are well-established probes with which one can measure cosmological parameters, and are complementary to other probes like the cosmic microwave ...background (CMB) or supernovae standard candles. Here we focus on dark GW sirens, specifically binary black holes (BBHs) for which there is only GW data. Our approach relies on the assumption of a source frame mass model for the BBH distribution, and we consider four models that are representative of the BBH population observed so far. In addition to inferring cosmological and mass model parameters, we use dark sirens to test modified gravity theories. These theories often predict different GW propagation equations on cosmological scales, leading to a different GW luminosity distance which in some cases can be parametrized by variables Ξ
0
and
n
. General relativity (GR) corresponds to Ξ
0
= 1. We perform a joint estimate of the population parameters governing mass, redshift, the variables characterizing the cosmology, and the modified GW luminosity distance. We use data from the third LIGO-Virgo-KAGRA observation run (O3) and find — for the four mass models and for three signal-to-noise ratio (SNR) cuts of 10, 11, 12 — that GR is consistently the preferred model to describe all observed BBH GW signals to date. Furthermore, all modified gravity parameters have posteriors that are compatible with the values predicted by GR at the 90% confidence interval (CI). We then focus on future observation runs O4 and O5, and for simplicity consider one specific mass model. We show that there are strong correlations between cosmological, astrophysical and modified gravity parameters. If GR is the correct theory of gravity, and assuming narrow priors on the cosmological parameters, we forecast an uncertainty of the modified gravity parameter Ξ
0
of 51% with ∼ 90 detections at O4-like sensitivities, and Ξ
0
of 20% with an additional ∼ 400 detections at O5-like sensitivity. We also consider how these forecasts depend on the current uncertainties of BBHs population distributions.
Abstract
Background
Adipose-derived stem cells (ADSC) are multipotent cells implicated in tissue homeostasis. Obesity represents a chronic inflammatory disease associated with metabolic dysfunction ...and age-related mechanisms, with progressive accumulation of senescent cells and compromised ADSC function. In this study, we aimed to explore mechanisms associated with the inflammatory environment present in obesity in modulating ADSC to a senescent phenotype. We evaluated phenotypic and functional alterations through 18 days of treatment. ADSC were cultivated with a conditioned medium supplemented with a pool of plasma from eutrophic individuals (PE, n = 15) or with obesity (PO, n = 14), and compared to the control.
Results
Our results showed that PO-treated ADSC exhibited decreased proliferative capacity with G2/M cycle arrest and
CDKN1A
(p21
WAF1/Cip1
) up-regulation. We also observed increased senescence-associated β-galactosidase (SA-β-gal) activity, which was positively correlated with TRF1 protein expression. After 18 days, ADSC treated with PO showed augmented
CDKN2A
(p16
INK4A
) expression, which was accompanied by a cumulative nuclear enlargement. After 10 days, ADSC treated with PO showed an increase in NF-κB phosphorylation, while PE and PO showed an increase in p38MAPK activation. PE and PO treatment also induced an increase in senescence-associated secretory phenotype (SASP) cytokines IL-6 and IL-8. PO-treated cells exhibited decreased metabolic activity, reduced oxygen consumption related to basal respiration, increased mitochondrial depolarization and biomass, and mitochondrial network remodeling, with no superoxide overproduction. Finally, we observed an accumulation of lipid droplets in PO-treated ADSC, implying an adaptive cellular mechanism induced by the obesogenic stimuli.
Conclusions
Taken together, our data suggest that the inflammatory environment observed in obesity induces a senescent phenotype associated with p38MAPK/NF-κB axis, which stimulates and amplifies the SASP and is associated with impaired mitochondrial homeostasis.
The merger of two neutron stars is predicted to give rise to three major detectable phenomena: a short burst of γ-rays, a gravitational-wave signal, and a transient optical-near-infrared source ...powered by the synthesis of large amounts of very heavy elements via rapid neutron capture (the r-process). Such transients, named 'macronovae' or 'kilonovae', are believed to be centres of production of rare elements such as gold and platinum. The most compelling evidence so far for a kilonova was a very faint near-infrared rebrightening in the afterglow of a short γ-ray burst at redshift z = 0.356, although findings indicating bluer events have been reported. Here we report the spectral identification and describe the physical properties of a bright kilonova associated with the gravitational-wave source GW170817 and γ-ray burst GRB 170817A associated with a galaxy at a distance of 40 megaparsecs from Earth. Using a series of spectra from ground-based observatories covering the wavelength range from the ultraviolet to the near-infrared, we find that the kilonova is characterized by rapidly expanding ejecta with spectral features similar to those predicted by current models. The ejecta is optically thick early on, with a velocity of about 0.2 times light speed, and reaches a radius of about 50 astronomical units in only 1.5 days. As the ejecta expands, broad absorption-like lines appear on the spectral continuum, indicating atomic species produced by nucleosynthesis that occurs in the post-merger fast-moving dynamical ejecta and in two slower (0.05 times light speed) wind regions. Comparison with spectral models suggests that the merger ejected 0.03 to 0.05 solar masses of material, including high-opacity lanthanides.
Purpose
Evaluation of obstetric and neonatal outcomes in a Brazilian retrospective cohort of pregnancies after Roux-en-Y gastric bypass (RYGB), regarding the 2009 Institute of Medicine (IOM) ...recommendations about gestational weight gain (GWG) and RYGB-conception interval. Additionally, search for intrapopulation risk factors for small gestational age (SGA) offspring and mental health assessments.
Material and methods
Retrospective analysis of 132 singleton pregnancies after RYGB. Obstetric and neonatal outcomes were analyzed with stratification in above, below, or meeting the target regarding GWG guidance, and 0–12, 12–47, and ≥48 months for RYGB-conception interval. SGA risk factors were identified through Poisson regression analysis.
Results
GWG below the recommendations was associated with prematurity (
p
0.003). Late conceptions (≥48 months) were associated with iron deficiency (
p
0.025). Parenteral iron prescription was a protective factor for SGA, with a relative risk of 0.41 (95% CI, 0.20–0.85;
p
0.017), and GWG below target was a SGA risk factor, with a relative risk of 4.68 (95% CI, 1.48–14.8;
p
0.008). In all, 15.2% of patients had psychopharmacological treatment during pregnancy, and 7.6% received a diagnosis of postpartum depression. Any alcohol and tobacco consumption were reported in 3.8 and 6.8% of patients, respectively.
Conclusion
The recommendations regarding GWG apply to the RYGB population, and surgery-conception intervals should be individualized. The parenteral iron prescription was a protective factor for SGA, and GWG below the recommendations of the IOM was a risk factor for SGA. Psychological and psychiatric care should be offered to every possible pregnancy after RYGB.
Graphical abstract
Background
Diabetes remission is not observed in all obese patients with type 2 diabetes submitted to bariatric surgery. Relapses occur in patients in whom remission is achieved. We investigated the ...factors associated with long-term (≥3 years) remission and relapse of type 2 diabetes after Roux-en-Y gastric bypass (RYGB) in these patients.
Methods
By a retrospective review, we analyzed data from 254 patients with type 2 diabetes who had undergone RYGB from May 2000 to November 2011 and had at least 3 years of follow-up. The criteria for remission and relapse of type 2 diabetes followed the current American Diabetes Association recommendations.
Results
Remission was achieved in almost 82% of participants (69.7% complete, and 12.2% partial remission). Of these, 12% relapsed within a mean follow-up of 5.1 ± 2.0 years after surgery. Predictors of complete remission were younger age, better preoperative glycemic control, and shorter diabetes duration. Preoperative insulin use was associated with a ninefold increase in the relapse hazard (HR = 9.1 (95% CI: 3.3–25.4)). Use of two or more oral anti-diabetic agents increased the relapse hazard sixfold (HR = 6.1 (95% CI: 1.8–20.6)). Eighteen point one percent of patients did not achieve any remission during follow-up. However, they exhibited significant improvements in glycemic control.
Conclusions
These data indicate that RYGB should not be delayed when remission of type 2 diabetes is a therapeutic goal, and also suggest that the best possible metabolic control should be sought in obese patients who may eventually be candidates for RYGB.
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