188 research outputs found
Integrated cardiovascular/respiratory control in type 1 diabetes evidences functional imbalance : Possible role of hypoxia
Background: Cardiovascular (baroreflex) and respiratory (chemoreflex) control mechanisms were studied separately in diabetes, but their reciprocal interaction (well known for diseases like heart failure) had never been comprehensively assessed. We hypothesized that prevalent autonomic neuropathy would depress both reflexes, whereas prevalent autonomic imbalance through sympathetic activation would depress the baroreflex but enhance the chemoreflexes. Methods: In 46 type-1 diabetic subjects (7.0 +/- 0.9 year duration) and 103 age-matched controls we measured the baroreflex (average of 7 methods), and the chemoreflexes, (hypercapnic: ventilation/carbon dioxide slope during hyperoxic progressive hypercapnia; hypoxic: ventilation/oxygen saturation slope during normocapnic progressive hypoxia). Autonomic dysfunction was evaluated by cardiovascular reflex tests. Results: Resting oxygen saturation and baroreflex sensitivity were reduced in the diabetic group, whereas the hypercapnic chemoreflex was significantly increased in the entire diabetic group. Despite lower oxygen saturation the hypoxic chemoreflex showed a trend toward a depression in the diabetic group. Conclusion: Cardio-respiratory control imbalance is a common finding in early type 1 diabetes. A reduced sensitivity to hypoxia seems a primary factor leading to reflex sympathetic activation (enhanced hypercapnic chemoreflex and baroreflex depression), hence suggesting a functional origin of cardio-respiratory control imbalance in initial diabetes. (C) 2017 Elsevier B.V. All rights reserved.Peer reviewe
Pseudogap and superconductivity in two-dimensional doped charge-transfer insulators
High-temperature superconductivity emerges in the CuO plane upon doping a
Mott insulator. To ascertain the influence of Mott physics plus short-range
correlations, we solve a three-band copper-oxide model in the charge-transfer
regime using cellular dynamical mean-field theory with continuous-time quantum
Monte Carlo as an impurity solver. We report the normal and superconducting
phase diagram of this model as a function of doping, interaction strength and
temperature. Upon hole doping of the charge-transfer insulator, the phase
boundary between pseudogap and correlated metal consists of a first-order
transition line at finite doping ending at a critical point, as in the one-band
model. Beyond the endpoint, the phase boundary continues as a Widom crossover
line, across which thermodynamic quantities peak. This phase boundary
determines changes in the pairing mechanism and is an emergent phenomenon
characteristic of doped Mott insulators, independent of many microscopic
details. Broader implications are discussed.Comment: 6 pages, 4 figures and supplementary information; published versio
Effects of interaction strength, doping, and frustration on the antiferromagnetic phase of the two-dimensional Hubbard model
Recent quantum-gas microscopy of ultracold atoms and scanning tunneling
microscopy of the cuprates reveal new detailed information about doped Mott
antiferromagnets, which can be compared with calculations. Using cellular
dynamical mean-field theory, we map out the antiferromagnetic (AF) phase of the
two-dimensional Hubbard model as a function of interaction strength , hole
doping and temperature . The N\'eel phase boundary is non-monotonic
as a function of and . Frustration induced by second-neighbor
hopping reduces N\'eel order more effectively at small . The doped AF is
stabilized at large by kinetic energy and at small by potential energy.
The transition between the AF insulator and the doped metallic AF is
continuous. At large , we find in-gap states similar to those observed in
scanning tunneling microscopy. We predict that, contrary to the Hubbard bands,
these states are only slightly spin polarized.Comment: 6 pages, 3 figures and supplemental informatio
Signatures of the Mott transition in the antiferromagnetic state of the two-dimensional Hubbard model
The properties of a phase with large correlation length can be strongly
influenced by the underlying normal phase. We illustrate this by studying the
half-filled two-dimensional Hubbard model using cellular dynamical mean-field
theory with continuous-time quantum Monte Carlo. Sharp crossovers in the
mechanism that favors antiferromagnetic correlations and in the corresponding
local density of states are observed. These crossovers occur at values of the
interaction strength and temperature that are controlled by the
underlying normal-state Mott transition.Comment: 5 pages, 3 figures and 4 appendices; published versio
Modulation of Phenylalanine and Tyrosine Metabolism in HIV-1 Infected Patients with Neurocognitive Impairment: Results from a Clinical Trial
To investigate the effects of oral bacteriotherapy on intestinal phenylalanine and tyrosine metabolism, in this longitudinal, double-arm trial, 15 virally suppressed HIV+ individuals underwent blood and fecal sample collection at baseline and after 6 months of oral bacteriotherapy. A baseline fecal sample was collected from 15 healthy individuals and served as control group for the baseline levels of fecal phenylalanine and tyrosine. CD4 and CD8 immune activation (CD38+) was evaluated by flow cytometry. Amino acid evaluation on fecal samples was conducted by Proton Nuclear Magnetic Resonance. Results showed that HIV+ participants displayed higher baseline phenylalanine/tyrosine ratio values than healthy volunteers. A significand reduction in phenylalanine/tyrosine ratio and peripheral CD4+ CD38+ activation was observed at the end of oral bacteriotherapy. In conclusion, probiotics beneficially affect the immune activation of HIV+ individuals. Therefore, the restoration of intestinal amino acid metabolism could represent the mechanisms through which probiotics exert these desirable effects
Antagonistic effects of nearest-neighbor repulsion on the superconducting pairing dynamics in the doped Mott insulator regime
The nearest-neighbor superexchange-mediated mechanism for d_{x^2-y^2}-wave
superconductivity in the one-band Hubbard model faces the challenge that
nearest-neighbor Coulomb repulsion can be larger than superexchange. To answer
this question, we use cellular dynamical mean-field theory (CDMFT) with a
continuous-time quantum Monte Carlo solver to determine the superconducting
phase diagram as a function of temperature and doping for on-site repulsion
and nearest-neighbor repulsion . In the underdoped regime,
increases the CDMFT superconducting transition temperature even
though it decreases the superconducting order parameter at low temperature for
all dopings. However, decreases in the overdoped regime. We gain
insight into these paradoxical results through a detailed study of the
frequency dependence of the anomalous spectral function, extracted at finite
temperature via the MaxEntAux method for analytic continuation. A systematic
study of dynamical positive and negative contributions to pairing reveals that
even though has a high-frequency depairing contribution, it also has a low
frequency pairing contribution since it can reinforce superexchange through
. Retardation is thus crucial to understand pairing in doped Mott
insulators, as suggested by previous zero-temperature studies. We also comment
on the tendency to charge order for large and on the persistence of d-wave
superconductivity over extended- or s+d-wave.Comment: Latex, 16 pages, 8 figure
Instrumental activities of daily living in older patients with metastatic prostate cancer: results from the meet-URO network ADHERE prospective study
Instrumental activities of daily living (IADL) are significant health indicators closely related to executive functions and able to detect mild cognitive impairment. A decline in IADL usually precedes ADL limitation, including taking medications, and may therefore predict a cognitive decline. We aimed to investigate the association of patients’ IADL score with other clinical factors, with a particular focus on the presence of a caregiver, and the impact on adherence to androgen receptor pathway inhibitors (ARPIs) and survival outcomes within the Meet-URO 5—ADHERE study. It was a large prospective multicentre observational cohort study monitoring adherence to ARPIs in 234 metastatic castrate-resistant PC (mCRPC) patients aged ≥ 70. We observed an association between impaired IADL and lower geriatric G8 scores (p < 0.01), and lower adherence to ARPIs whether assessed by pill counting (p = 0.01) or self-reported by the patient himself (p = 0.03). The combination of an IADL < 6 and the absence of a caregiver resulted in a significantly high risk of non-adherence to the ARPIs at the multivariable analysis (HR 9.23, 95% confidence interval 2.28–37.43, p = 0.01). IADL alongside the geriatric G8 scales represent essential tools to identify frail and less auto-sufficient patients who are extremely vulnerable particularly if not supported by a caregiver and have the highest risk of nonadherence to ARPIs
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