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result(s) for
"E. Perez"
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A Randomized Trial of Erythropoietin for Neuroprotection in Preterm Infants
by
Comstock, Bryan A
,
Wadhawan, Rajan
,
Vu, Phuong T
in
Body weight
,
Brain - diagnostic imaging
,
Brain injury
2020
In this multicenter, randomized trial involving extremely preterm infants, high-dose erythropoietin administered from 24 hours after birth through 32 weeks of postmenstrual age did not result in a lower risk of severe neurodevelopmental impairment or death at 2 years of age.
Journal Article
FXR is a molecular target for the effects of vertical sleeve gastrectomy
by
Myronovych, Andriy
,
Bäckhed, Fredrik
,
Wilson-Pérez, Hilary E.
in
631/443/319/1642/2037
,
Acids
,
Animals
2014
Bariatric surgical procedures, such as vertical sleeve gastrectomy (VSG), are at present the most effective therapy for the treatment of obesity, and are associated with considerable improvements in co-morbidities, including type-2 diabetes mellitus. The underlying molecular mechanisms contributing to these benefits remain largely undetermined, despite offering the potential to reveal new targets for therapeutic intervention. Substantial changes in circulating total bile acids are known to occur after VSG. Moreover, bile acids are known to regulate metabolism by binding to the nuclear receptor FXR (farsenoid-X receptor, also known as NR1H4). We therefore examined the results of VSG surgery applied to mice with diet-induced obesity and targeted genetic disruption of FXR. Here we demonstrate that the therapeutic value of VSG does not result from mechanical restriction imposed by a smaller stomach. Rather, VSG is associated with increased circulating bile acids, and associated changes to gut microbial communities. Moreover, in the absence of FXR, the ability of VSG to reduce body weight and improve glucose tolerance is substantially reduced. These results point to bile acids and FXR signalling as an important molecular underpinning for the beneficial effects of this weight-loss surgery.
Bariatric surgical procedures, such as vertical sleeve gastrectomy (VSG), are the most effective therapy for the treatment of obesity; now bile acids, and the presence of the nuclear bile acid receptor FXR, are shown to underpin the mechanism of VSG action, and the ability of VSG to reduce body weight and improve glucose tolerance is substantially reduced if FXR is absent.
How weight-loss surgery works
The use and misuse of invasive surgery to control obesity and related conditions is much debated. Whatever its merits, the associated costs and risks mean that it is inappropriate in many cases. This study challenges the notion that such surgery elicits weight loss solely by making it physically difficult to consume or absorb calories, and raises the prospect that it may be possible to develop therapies that achieve the same ends without the need for a scalpel. Vertical sleeve gastrectomy (VSG), in which some 80% of the stomach is removed to create a gastric 'sleeve' contiguous with the oesophagus and duodenum, is known to induce loss of body weight and fat mass, and improves glucose tolerance in humans and rodents. Randy Seeley and colleagues show here that the therapeutic effect of VSG in mice arises not from the mechanical restrictions of a smaller stomach but from the associated increase in the levels of circulating bile acids and changes to gut microbial communities. Moreover, in the absence of nuclear bile acid receptor FXR, the ability of VSG to reduce body weight and improve glucose tolerance is substantially reduced.
Journal Article
SD-OCT Analysis of Regional Epithelial Thickness Profiles in Keratoconus, Postoperative Corneal Ectasia, and Normal Eyes
by
Randleman, J. Bradley
,
Rocha, Karolinne Maia
,
Perez-Straziota, E.
in
Cornea
,
Corneal Pachymetry
,
Dilatation, Pathologic - pathology
2013
To assess corneal microarchitecture and regional epithelial thickness profile in eyes with keratoconus, postoperative corneal ectasia (ectasia), and normal unoperated eyes (controls) using spectral-domain optical coherence tomography (SD-OCT).
Regional corneal epithelial thickness profiles were measured with anterior segment SD-OCT (Optovue RTVue-100, Optovue Inc., Fremont, CA). Epithelial thickness was assessed at 21 points, 0.5 mm apart, across the central 6-mm of the corneal apex in the horizontal and vertical meridians.
One hundred twenty eyes were evaluated, including 49 eyes from 29 patients with keratoconus, 32 eyes from 16 patients with ectasia, and 39 eyes from 21 control patients. Average epithelial thickness at the corneal apex was 41.18 ± 6.47 μm (range: 30 to 51 μm) for keratoconus, 46.5 ± 6.72 μm for ectasia (range: 34 to 60 μm), and 50.45 ± 3.92 μm for controls (range: 42 to 55 μm). Apical epithelial thickness was significantly thinner in eyes with keratoconus (P < .0001) and ectasia (P = .0007) than in controls. Epithelial thickness ranges in all other areas varied widely for keratoconus (range: 21 to 101 μm) and ectasia (range: 30 to 82 μm) compared to controls (range: 43 to 64) (P = .0063).
SD-OCT demonstrated significant central and regional epithelial thickness profile differences between keratoconus, ectasia, and control eyes, with significant variability and unpredictability in ectatic eyes. This regional irregularity may necessitate direct epithelial thickness measurement for treatments where underlying stromal variations may be clinically relevant, including corneal collagen cross-linking or topography-guided ablations.
Journal Article
Type I Interferon (IFN)-Regulated Activation of Canonical and Non-Canonical Signaling Pathways
by
Fish, Eleanor N.
,
Platanias, Leonidas C.
,
Perez, Ricardo E.
in
Animals
,
Autoimmune diseases
,
Bioinformatics
2020
For several decades there has been accumulating evidence implicating type I interferons (IFNs) as key elements of the immune response. Therapeutic approaches incorporating different recombinant type I IFN proteins have been successfully employed to treat a diverse group of diseases with significant and positive outcomes. The biological activities of type I IFNs are consequences of signaling events occurring in the cytoplasm and nucleus of cells. Biochemical events involving JAK/STAT proteins that control transcriptional activation of IFN-stimulated genes (ISGs) were the first to be identified and are referred to as “canonical” signaling. Subsequent identification of JAK/STAT-independent signaling pathways, critical for ISG transcription and/or mRNA translation, are denoted as “non-canonical” or “non-classical” pathways. In this review, we summarize these signaling cascades and discuss recent developments in the field, specifically as they relate to the biological and clinical implications of engagement of both canonical and non-canonical pathways.
Journal Article
Elevational and seasonal patterns of plant pollinator networks in two highland tropical ecosystems in Costa Rica
by
Martén-Rodríguez, Silvana
,
Hanson, Paul
,
Gamboa-Barrantes, Nicole
in
Alpine environments
,
Analysis
,
Biological diversity
2024
Many plant species in high montane ecosystems rely on animal pollination for sexual reproduction, however, our understanding of plant-pollinator interactions in tropical montane habitats is still limited. We compared species diversity and composition of blooming plants and floral visitors, and the structure of plant-floral visitor networks between the Montane Forest and Paramo ecosystems in Costa Rica. We also studied the influence of seasonality on species composition and interaction structure. Given the severe climatic conditions experienced by organisms in habitats above treeline, we expected lower plant and insect richness, as well as less specialized and smaller pollination networks in the Paramo than in Montane Forest where climatic conditions are milder and understory plants are better protected. Accordingly, we found that blooming plants and floral visitor species richness was higher in the Montane Forest than in the Paramo, and in both ecosystems species richness of blooming plants and floral visitors was higher in the rainy season than in the dry season. Interaction networks in the Paramo were smaller and more nested, with lower levels of specialization and modularity than those in the Montane Forest, but there were no seasonal differences within either ecosystem. Beta diversity analyses indicate that differences between ecosystems are likely explained by species turnover, whereas within the Montane Forest differences between seasons are more likely explained by the rewiring of interactions. Results indicate that the decrease in species diversity with elevation affects network structure, increasing nestedness and reducing specialization and modularity.
Journal Article
Vertical Sleeve Gastrectomy Is Effective in Two Genetic Mouse Models of Glucagon-Like Peptide 1 Receptor Deficiency
by
Wilson-Pérez, Hilary E.
,
Sandoval, Darleen A.
,
Drucker, Daniel J.
in
Animals
,
Biological and medical sciences
,
Body Composition - drug effects
2013
Glucagon-like peptide 1 (GLP-1) is a peptide hormone that is released from the gut in response to nutrient ingestion and that has a range of metabolic effects, including enhancing insulin secretion and decreasing food intake. Postprandial GLP-1 secretion is greatly enhanced in rats and humans after some bariatric procedures, including vertical sleeve gastrectomy (VSG), and has been widely hypothesized to contribute to reduced intake, weight loss, and the improvements in glucose homeostasis after VSG. We tested this hypothesis using two separate models of GLP-1 receptor deficiency. We found that VSG-operated GLP-1 receptor–deficient mice responded similarly to wild-type controls in terms of body weight and body fat loss, improved glucose tolerance, food intake reduction, and altered food selection. These data demonstrate that GLP-1 receptor activity is not necessary for the metabolic improvements induced by VSG surgery.
Journal Article
Excessive fructose intake induces the features of metabolic syndrome in healthy adult men: role of uric acid in the hypertensive response
by
Sánchez-Lozada, L.G
,
Schold, J
,
López Lillo, J
in
administration & dosage
,
Adult
,
adverse effects
2010
Background: Excessive fructose intake causes metabolic syndrome in animals and can be partially prevented by lowering the uric acid level. We tested the hypothesis that fructose might induce features of metabolic syndrome in adult men and whether this is protected by allopurinol. Methods: A randomized, controlled trial of 74 adult men who were administered 200 g fructose daily for 2 weeks with or without allopurinol. Primary measures included changes in ambulatory blood pressure (BP), fasting lipids, glucose and insulin, homeostatic model assessment (HOMA) index, body mass index and criteria for metabolic syndrome. Results: The ingestion of fructose resulted in an increase in ambulatory BP (7±2 and 5±2 mm Hg for systolic (SBP) and diastolic BP (DBP), P<0.004 and P<0.007, respectively). Mean fasting triglycerides increased by 0.62±0.23 mmol l−1 (55±20 mg per 100 ml), whereas high-density lipoprotein cholesterol decreased by 0.06±0.02 mmol l−1 (2.5±0.7 mg per 100 ml), P<0.002 and P<0.001, respectively. Fasting insulin and HOMA indices increased significantly, whereas plasma glucose level did not change. All liver function tests showed an increase in values. The metabolic syndrome increased by 25–33% depending on the criteria. Allopurinol lowered the serum uric acid level (P<0.0001) and prevented the increase in 24-h ambulatory DBP and daytime SBP and DBP. Allopurinol treatment did not reduce HOMA or fasting plasma triglyceride levels, but lowered low-density lipoprotein cholesterol relative to control (P<0.02) and also prevented the increase in newly diagnosed metabolic syndrome (0–2%, P=0.009). Conclusions: High doses of fructose raise the BP and cause the features of metabolic syndrome. Lowering the uric acid level prevents the increase in mean arterial blood pressure. Excessive intake of fructose may have a role in the current epidemics of obesity and diabetes.
Journal Article
Timing-based mass measurement of exotic long-lived particles at the FCC-ee
2025
The very high luminosity run foreseen at the
Z
-pole for the FCC-ee will allow the detection in
Z
decays of new particles with very low couplings to the Standard Model. These particles can have measurable flight paths before they decay. If the timing and the position of the decay vertex can be measured with high precision, the mass of such particles can be measured by exploiting the constrained kinematics of an
e
+
e
-
collider. The mass resolution achievable with this technique is studied through a detailed analysis in the framework of a parametrised simulation of the performance of the IDEA detector. The adopted benchmark model is the production of Heavy Neutral Leptons, which is one of the key channels for new physics discovery at the FCC-ee.
Journal Article
Deciphering rhizosphere microbiome assembly of wild and modern common bean (Phaseolus vulgaris) in native and agricultural soils from Colombia
by
Raaijmakers, Jos M.
,
Carrión, Víctor J.
,
de Hollander, Mattias
in
Agricultural industry
,
Analysis
,
Bacteria - isolation & purification
2019
Background
Modern crop varieties are typically cultivated in agriculturally well-managed soils far from the centers of origin of their wild relatives. How this habitat expansion impacted plant microbiome assembly is not well understood.
Results
Here, we investigated if the transition from a native to an agricultural soil affected rhizobacterial community assembly of wild and modern common bean (
Phaseolus vulgaris
) and if this led to a depletion of rhizobacterial diversity. The impact of the bean genotype on rhizobacterial assembly was more prominent in the agricultural soil than in the native soil. Although only 113 operational taxonomic units (OTUs) out of a total of 15,925 were shared by all eight bean accessions grown in native and agricultural soils, this core microbiome represented a large fraction (25.9%) of all sequence reads. More OTUs were exclusively found in the rhizosphere of common bean in the agricultural soil as compared to the native soil and in the rhizosphere of modern bean accessions as compared to wild accessions. Co-occurrence analyses further showed a reduction in complexity of the interactions in the bean rhizosphere microbiome in the agricultural soil as compared to the native soil.
Conclusions
Collectively, these results suggest that habitat expansion of common bean from its native soil environment to an agricultural context had an unexpected overall positive effect on rhizobacterial diversity and led to a stronger bean genotype-dependent effect on rhizosphere microbiome assembly.
Journal Article
Forecast-based financing: an approach for catalyzing humanitarian action based on extreme weather and climate forecasts
by
Jongman, B.
,
van den Hurk, B.
,
Suarez, P.
in
Climate change
,
Extreme weather
,
open climate campaign
2015
Disaster risk reduction efforts traditionally focus on long-term preventative measures or post-disaster response. Outside of these, there are many short-term actions, such as evacuation, that can be implemented in the period of time between a warning and a potential disaster to reduce the risk of impacts. However, this precious window of opportunity is regularly overlooked in the case of climate and weather forecasts, which can indicate heightened risk of disaster but are rarely used to initiate preventative action. Barriers range from the protracted debate over the best strategy for intervention to the inherent uncomfortableness on the part of donors to invest in a situation that will likely arise but is not certain. In general, it is unclear what levels of forecast probability and magnitude are \"worth\" reacting to. Here, we propose a novel forecast-based financing system to automatically trigger action based on climate forecasts or observations. The system matches threshold forecast probabilities with appropriate actions, disburses required funding when threshold forecasts are issued, and develops standard operating procedures that contain the mandate to act when these threshold forecasts are issued. We detail the methods that can be used to establish such a system, and provide illustrations from several pilot cases. Ultimately, such a system can be scaled up in disaster-prone areas worldwide to improve effectiveness at reducing the risk of disaster.
Journal Article