75 research outputs found
The effect of a single dose of beetroot juice on speed, strength, and power in healthy recreationally active females.
Nitrate-rich beetroot juice (BR) improves muscle contraction which is relevant for intense intermittent-type sports. However, few studies have examined the effect of BR ingestion on performance using sport-specific exercise protocols. Moreover, there is a scarcity of research that include female participants which limits real world application given that females potentially have different responses to BR ingestion. The purpose of the present study was to examine the effect of BR supplementation on speed, acceleration, strength and power before and after fatigue in females. In a double-blind, randomized crossover design, 15 recreationally active females consumed BR and nitrate-depleted placebo juice (PL) ~2.5 hours prior to exercise testing. Measurements included 20 m sprint and acceleration using timing gates, strength using isokinetic handgrip dynamometry, and upper and lower body power using the medicine ball power throw and countermovement jump (CMJ) before and after a fatiguing running protocol. Data from a subset of participants (n=15) were analyzed and revealed no significant difference between PL and BR for 20 m speed and 10 m acceleration (P\u3e0.05), isokinetic handgrip dynamometry (PL: PRE: 76±10 vs POST: 76±13; BR: PRE: 78±12 vs POST: 78±12 lb; P\u3e0.05), medicine ball power throw (PL: PRE: 4.45±0.48 vs POST: 4.35±0.48; BR: PRE: 4.41±0.38 vs POST: 4.49±0.47 m; P\u3e0.05) or CMJ (PL: PRE: 1.72±0.27 vs POST: 1.7±0.26; BR: PRE: 1.77±0.25 vs POST: 1.73±0.28 m; P\u3e0.05). These results indicate that there are no effects of BR supplementation on exercise performance in female athletes; however, this study is currently underpowered, and research is still in progress
The effects of nitrate-rich beetroot juice supplementation on nonverbal executive function in healthy recreationally active females
Nitrate-rich beetroot juice (BR) supplementation has been reported to preserve executive function (i.e. decision making and reaction time) before and after a simulated soccer match in recreationally active males, which may be due to enhanced cerebral blood flow. However, the literature examining the physiological response following BR ingestion in females is scarce, which hampers the extrapolation of results since physiological sex-differences may exist. Therefore, the purpose of this study was to assess if BR ingestion influenced executive function in an unfatigued and fatigued state in healthy recreationally active females. In a double-blind, randomized crossover design, 20 females consumed 140 mL of concentrated BR or nitrate-depleted placebo juice (PL) approximately 2.5 hours prior to each experimental visit. The Delis-Kaplan Executive Function (D-KEF) test, used for assessing higher-level cognitive function, was administered before and after completing a high-intensity intermittent running protocol. The D-KEF test involved 3 x 60-s conditions evaluating various cognitive tasks. A two-way repeated measures analysis of variance was conducted (n=15) and revealed no significant differences in executive function between PL (PRE: 15.27 ± 32.71 vs. POST: 16.93 ± 1.44) and BR (PRE: 15.80 ± 2.65 vs. POST: 16.60 ± 1.88). These preliminary data suggest that acute BR ingestion does not have an influence on processing and creative thinking of nonverbal executive function in an unfatigued or fatigued state in healthy recreationally active females, although importantly, the study is still in progress
The Effects of Acute Beetroot Juice Ingestion on Exercise and Cognitive Performance in Female Athletes
Nitrate-rich beetroot juice can enhance intense exercise performance which is attributed to enhanced skeletal muscle contractility. However, limited data exist in females and it is unknown whether dietary nitrate has an ergogenic effect in this population. PURPOSE: To investigate the potential effects of acute nitrate ingestion on a battery of exercise performance and cognitive tests before and after fatiguing intermittent running exercise. METHODS: Fifteen female team-sport athletes were assigned in a randomized, double-blind, crossover design to consume nitrate-rich beetroot juice (BR; 12 mmol of nitrate) and nitrate-depleted beetroot juice (PL; 0.10 mmol of nitrate) 2.5 h prior to performing the exercise protocol, with a washout period of 7 days between trials. Running 10 m and 20 m sprint split times, sprint reaction time, upper- and lower-body power, handgrip strength, and cognitive flexibility were measured before and after the Yo-Yo intermittent recovery level 1 (Yo-Yo IR1) test, during which performance and rate of perceived exertion were recorded. RESULTS: There were no significant differences in any performance outcome or cognitive flexibility (P \u3e 0.05). CONCLUSION: These findings indicate that acute nitrate ingestion does not influence performance in sprints, intermittent running, power, strength, or cognitive function in young adult female team-sport athletes
Silent progression in disease activity-free relapsing multiple sclerosis.
ObjectiveRates of worsening and evolution to secondary progressive multiple sclerosis (MS) may be substantially lower in actively treated patients compared to natural history studies from the pretreatment era. Nonetheless, in our recently reported prospective cohort, more than half of patients with relapsing MS accumulated significant new disability by the 10th year of follow-up. Notably, "no evidence of disease activity" at 2âyears did not predict long-term stability. Here, we determined to what extent clinical relapses and radiographic evidence of disease activity contribute to long-term disability accumulation.MethodsDisability progression was defined as an increase in Expanded Disability Status Scale (EDSS) of 1.5, 1.0, or 0.5 (or greater) from baseline EDSSâ=â0, 1.0-5.0, and 5.5 or higher, respectively, assessed from baseline to year 5 (±1âyear) and sustained to year 10 (±1âyear). Longitudinal analysis of relative brain volume loss used a linear mixed model with sex, age, disease duration, and HLA-DRB1*15:01 as covariates.ResultsRelapses were associated with a transient increase in disability over 1-year intervals (pâ=â0.012) but not with confirmed disability progression (pâ=â0.551). Relative brain volume declined at a greater rate among individuals with disability progression compared to those who remained stable (pâ<â0.05).InterpretationLong-term worsening is common in relapsing MS patients, is largely independent of relapse activity, and is associated with accelerated brain atrophy. We propose the term silent progression to describe the insidious disability that accrues in many patients who satisfy traditional criteria for relapsing-remitting MS. Ann Neurol 2019;85:653-666
Delayed Stellar Mass Assembly in the Low Surface Brightness Dwarf Galaxy KDG215
We present HI spectral line and optical broadband images of the nearby low
surface brightness dwarf galaxy KDG215. The HI images, acquired with the Karl
G. Jansky Very Large Array (VLA), reveal a dispersion dominated ISM with only
weak signatures of coherent rotation. The HI gas reaches a peak mass surface
density of 6 M pc at the location of the peak surface
brightness in the optical and the UV. Although KDG215 is gas-rich, the
H non-detection implies a very low current massive star formation rate.
In order to investigate the recent evolution of this system, we have derived
the recent and lifetime star formation histories from archival Hubble Space
Telescope images. The recent star formation history shows a peak star formation
rate 1 Gyr ago, followed by a decreasing star formation rate to the
present day quiescent state. The cumulative star formation history indicates
that a significant fraction of the stellar mass assembly in KDG215 has occurred
within the last 1.25 Gyr. KDG215 is one of only a few known galaxies which
demonstrates such a delayed star formation history. While the ancient stellar
population (predominantly red giants) is prominent, the look-back time by which
50% of the mass of all stars ever formed had been created is among the youngest
of any known galaxy.Comment: Accepted for publication in the Astrophysical Journal Letter
Spectroscopic and Mechanistic Studies of Heterodimetallic Forms of Metallo-ÎČ-lactamase NDM-1
In an effort to characterize the roles of each metal ion in metallo-ÎČ-lactamase NDM-1, heterodimetallic analogues (CoCo-, ZnCo-, and CoCd-) of the enzyme were generated and characterized. UVâvis, 1H NMR, EPR, and EXAFS spectroscopies were used to confirm the fidelity of the metal substitutions, including the presence of a homogeneous, heterodimetallic cluster, with a single-atom bridge. This marks the first preparation of a metallo-ÎČ-lactamase selectively substituted with a paramagnetic metal ion, Co(II), either in the Zn1 (CoCd-NDM-1) or in the Zn2 site (ZnCo-NDM-1), as well as both (CoCo-NDM-1). We then used these metal-substituted forms of the enzyme to probe the reaction mechanism, using steady-state and stopped-flow kinetics, stopped-flow fluorescence, and rapid-freeze-quench EPR. Both metal sites show significant effects on the kinetic constants, and both paramagnetic variants (CoCd- and ZnCo-NDM-1) showed significant structural changes on reaction with substrate. These changes are discussed in terms of a minimal kinetic mechanism that incorporates all of the data
Spinal Cord Atrophy Predicts Progressive Disease in Relapsing Multiple Sclerosis
Objective A major challenge in multiple sclerosis (MS) research is the understanding of silent progression and Progressive MS. Using a novel method to accurately capture upper cervical cord area from legacy brain MRI scans we aimed to study the role of spinal cord and brain atrophy for silent progression and conversion to secondary progressive disease (SPMS). Methods From a single-center observational study, all RRMS (n = 360) and SPMS (n = 47) patients and 80 matched controls were evaluated. RRMS patient subsets who converted to SPMS (n = 54) or silently progressed (n = 159), respectively, during the 12-year observation period were compared to clinically matched RRMS patients remaining RRMS (n = 54) or stable (n = 147), respectively. From brain MRI, we assessed the value of brain and spinal cord measures to predict silent progression and SPMS conversion. Results Patients who developed SPMS showed faster cord atrophy rates (-2.19%/yr) at least 4 years before conversion compared to their RRMS matches (-0.88%/yr, p < 0.001). Spinal cord atrophy rates decelerated after conversion (-1.63%/yr, p = 0.010) towards those of SPMS patients from study entry (-1.04%). Each 1% faster spinal cord atrophy rate was associated with 69% (p < 0.0001) and 53% (p < 0.0001) shorter time to silent progression and SPMS conversion, respectively. Interpretation Silent progression and conversion to secondary progressive disease are predominantly related to cervical cord atrophy. This atrophy is often present from the earliest disease stages and predicts the speed of silent progression and conversion to Progressive MS. Diagnosis of SPMS is rather a late recognition of this neurodegenerative process than a distinct disease phase. ANN NEUROL 202
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Clinical Characteristics and Outcomes of Drug-Induced Acute Kidney Injury Cases
Introduction
Drug-induced acute kidney injury (DI-AKI) is a frequent adverse event. The identification of DI-AKI is challenged by competing etiologies, clinical heterogeneity among patients, and a lack of accurate diagnostic tools. Our research aims to describe the clinical characteristics and predictive variables of DI-AKI.
Methods
We analyzed data from the DIRECT study (NCT02159209), an international, multi-center, observational cohort study of enriched clinically adjudicated DI-AKI cases. Cases met the primary inclusion criteria if the patient was exposed to at least one nephrotoxic drug for a minimum of 24 hours prior to acute kidney injury (AKI) onset. Cases were clinically adjudicated and inter-rater reliability (IRR) was measured using Krippendorff's alpha. Variables associated with DI-AKI were identified using L1 regularized multivariable logistic regression. Model performance was assessed using the area under the receiver operating characteristic curve (ROC AUC).
Results
314 AKI cases met the eligibility criteria for this analysis, and 271 (86%) cases were adjudicated as DI-AKI. The majority of the AKI cases were recruited from the United States (68%). The most frequent causal nephrotoxic drugs were vancomycin (48.7%), non-steroidal anti-inflammatory drugs (18.2%), and piperacillin/tazobactam (17.8%). The IRR for DI-AKI adjudication was 0.309. The multivariable model identified age, vascular capacity, hyperglycemia, infections, pyuria, serum creatinine trends, and contrast media as significant predictors of DI-AKI with good performance, ROC AUC 0.86.
Conclusions
The identification of DI-AKI is challenging even with comprehensive adjudication by experienced nephrologists. Our analysis identified key clinical characteristics and outcomes of DI-AKI compared to other AKI etiologies
Defining the causes of sporadic Parkinson's disease in the global Parkinson's genetics program (GP2)
The Global Parkinsonâs Genetics Program (GP2) will genotype over 150,000 participants from around the world, and integrate genetic and clinical data for use in large-scale analyses to dramatically expand our understanding of the genetic architecture of PD. This report details the workflow for cohort integration into the complex arm of GP2, and together with our outline of the monogenic hub in a companion paper, provides a generalizable blueprint for establishing large scale collaborative research consortia
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