bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tissue and sex specificities in Ca2+ handling by isolated mitochondria in conditions avoiding the permeability transition
Authors: Chweih Hanan , Castilho Roger F. , Figueira Tiago R. 
Published: June 2015

New Findings

What is the central question of this study?
The assessment of Ca2+ handling by isolated mitochondria can be biased by dysfunctions secondary to Ca2+‐induced mitochondrial permeability transition (MPT). As a result of this uncertainty and the differing experimental conditions between studies, the tissue and sex diversities in mitochondrial Ca2+ transport are still unsettled questions.

What is the main finding and its importance?
If MPT is not prevented during Ca2+ transport assays, some measured variables are biased. Accounting for the implied importance of preventing MPT, we observed substantial tissue specificities in the mitochondrial Ca2+ handling, particularly in the Ca2+ efflux pathways.

The characteristics of mitochondria, including their Ca2+ transport functions, may exhibit tissue specificity and sexual dimorphism. Given that measurements of Ca2+ handling by isolated mitochondria may be biased by dysfunction secondary to Ca2+‐induced mitochondrial permeability transition (MPT) pore opening, this study evaluated the extent to which MPT inhibition by ciclosporin affected the measurement of Ca2+ transport in isolated rat liver mitochondria. The results indicate that the steady‐state levels of external Ca2+ and the rates of mitochondrial Ca2+ efflux through the selective pathways can be overestimated by up to fourfold if MPT pore opening is not prevented. We analysed Ca2+ transport in isolated mitochondria from the liver, skeletal muscle, heart and brain of male and female rats in incubation conditions containing MPT inhibitors, NAD‐linked substrates and relevant levels of free Ca2+, Mg2+ and Na+. The Ca2+ influx rates were similar among the samples, except that the liver mitochondria displayed values fourfold higher. In contrast, the Ca2+ efflux rates exhibited more tissue diversity, especially in the presence of Na+. Interestingly, the Na+‐independent Ca2+ efflux was highest in the heart mitochondria (∼4 nmol mg−1 min−1), thus challenging the view that cardiac mitochondrial Ca2+ efflux relies almost exclusively on a Na+‐dependent pathway. Sex specificity was observed in only two kinetic indexes of heart mitochondrial Ca2+ homeostasis and in the ADP‐stimulated respiration of liver mitochondria (∼20% higher in females). The present study shows the methodological importance of preventing MPT when measuring the properties and the physiological variability of the Ca2+ handling by isolated mitochondria.
Fluid restriction during exercise in the heat reduces tolerance to progressive central hypovolaemia
Authors: Schlader Zachary J. , Gagnon Daniel , Rivas Eric , Convertino Victor A. , Crandall Craig G. 
Published: June 2015

New Findings

What is the central question of this study?
Interactions between dehydration, as occurs during exercise in the heat without fluid replacement, and hyperthermia on the ability to tolerate central hypovolaemia are unknown.

What is the main finding and its importance?
We show that inadequate fluid intake during exercise in the heat can impair tolerance to central hypovolaemia even when it elicits only mild dehydration. These findings suggest that hydration during physical work in the heat has important military and occupational relevance for protection against the adverse effects of a subsequent haemorrhagic injury.

This study tested the hypothesis that dehydration induced via exercise in the heat impairs tolerance to central hypovolaemia. Eleven male subjects (32 ± 7 years old, 81.5 ± 11.1 kg) walked (O2 uptake 1.7 ± 0.4 l min−1) in a 40°C, 30% relative humidity environment on three occasions, as follows: (i) subjects walked for 90 min, drinking water to offset sweat loss (Hydrated, n = 11); (ii) water intake was restricted, and exercise was terminated when intestinal temperature increased to the same level as in the Hydrated trial (Isothermic Dehydrated, n = 11); and (iii) water intake was restricted, and exercise duration was 90 min (Time Match Dehydrated, n = 9). For each trial, tolerance to central hypovolaemia was determined following exercise via progressive lower body negative pressure and quantified as time to presyncope. Increases in intestinal temperature prior to lower body negative pressure were not different (P = 0.91) between Hydrated (1.1 ± 0.4°C) and Isothermic Dehydrated trials (1.1 ± 0.4°C), but both were lower than in the Time Match Dehydrated trial (1.7 ± 0.5°C, P < 0.01). Prior to lower body negative pressure, body weight was unchanged in the Hydrated trial (−0.1 ± 0.2%), but was reduced in Isothermic Dehydrated (−0.9 ± 0.4%) and further so in Time Match Dehydrated trial (−1.9 ± 0.6%, all P < 0.01). Time to presyncope was greater in Hydrated (14.7 ± 3.2 min) compared with Isothermic Dehydrated (11.9 ± 3.3 min, P < 0.01) and Time Match Dehydrated trials (10.2 ± 1.6 min, P = 0.03), which were not different (P = 0.19). These data indicate that inadequate fluid intake during exercise in the heat reduces tolerance to central hypovolaemia independent of increases in body temperature.
Synergistic role of ADP and Ca2+ in diastolic myocardial stiffness
Authors: Sequeira Vasco , Najafi Aref , McConnell Mark , Fowler Ewan D. , Bollen Ilse A. E. , Wüst Rob C. I. , dos Remedios Cris , Helmes Michiel , White Ed , Stienen Ger J. M. , Tardiff Jil , Kuster Diederik W. D. , van der Velden Jolanda 
Published: June 2015

Key points
Diastolic dysfunction in heart failure patients is evident from stiffening of the passive properties of the ventricular wall.
Increased actomyosin interactions may significantly limit diastolic capacity, however, direct evidence is absent.
From experiments at the cellular and whole organ level, in humans and rats, we show that actomyosin‐related force development contributes significantly to high diastolic stiffness in environments where high ADP and increased diastolic [Ca2+] are present, such as the failing myocardium.
Our basal study provides a mechanical mechanism which may partly underlie diastolic dysfunction.
AbstractHeart failure (HF) with diastolic dysfunction has been attributed to increased myocardial stiffness that limits proper filling of the ventricle. Altered cross‐bridge interaction may significantly contribute to high diastolic stiffness, but this has not been shown thus far. Cross‐bridge interactions are dependent on cytosolic [Ca2+] and the regeneration of ATP from ADP. Depletion of myocardial energy reserve is a hallmark of HF leading to ADP accumulation and disturbed Ca2+ handling. Here, we investigated if ADP elevation in concert with increased diastolic [Ca2+] promotes diastolic cross‐bridge formation and force generation and thereby increases diastolic stiffness. ADP dose‐dependently increased force production in the absence of Ca2+ in membrane‐permeabilized cardiomyocytes from human hearts. Moreover, physiological levels of ADP increased actomyosin force generation in the presence of Ca2+ both in human and rat membrane‐permeabilized cardiomyocytes. Diastolic stress measured at physiological lattice spacing and 37°C in the presence of pathological levels of ADP and diastolic [Ca2+] revealed a 76 ± 1% contribution of cross‐bridge interaction to total diastolic stress in rat membrane‐permeabilized cardiomyocytes. Inhibition of creatine kinase (CK), which increases cytosolic ADP, in enzyme‐isolated intact rat cardiomyocytes impaired diastolic re‐lengthening associated with diastolic Ca2+ overload. In isolated Langendorff‐perfused rat hearts, CK inhibition increased ventricular stiffness only in the presence of diastolic [Ca2+]. We propose that elevations of intracellular ADP in specific types of cardiac disease, including those where myocardial energy reserve is limited, contribute to diastolic dysfunction by recruiting cross‐bridges, even at low Ca2+, and thereby increase myocardial stiffness.
Enhanced BDNF signalling following chronic hypoxia potentiates catecholamine release from cultured rat adrenal chromaffin cells
Authors: Scott Angela L. , Zhang Min , Nurse Colin A. 
Published: June 2015

Key points
We investigated the role of the neurotrophin BDNF signalling via the TrkB receptor in rat adrenomedullary chromaffin cells (AMCs) exposed to normoxia (Nox; 21% O2) and chronic hypoxia (CHox; 2% O2) in vitro for ∼48 h.
TrkB receptor expression was upregulated in primary AMCs and in immortalized chromaffin (MAH) cells exposed to CHox; this effect was absent in MAH cells deficient in the transcription factor, hypoxia inducible factor (HIF)‐2α.
Relative to normoxic controls, activation of the TrkB receptor in chronically hypoxic AMCs led to a marked increase in membrane excitability, intracellular [Ca2+], and catecholamine secretion.
The BDNF‐induced rise of intracellular [Ca2+] in CHox cells was sensitive to the selective T‐type Ca2+ channel blocker TTA‐P2 and tetrodotoxin (TTX), suggesting key roles of low threshold T‐type Ca2+ and voltage‐gated Na+ channels in the signalling pathway.
AbstractEnvironmental stressors, including chronic hypoxia, enhance the ability of adrenomedullary chromaffin cells (AMCs) to secrete catecholamines; however, the underlying molecular mechanisms remain unclear. Here, we investigated the role of brain‐derived neurotrophic factor (BDNF) signalling in rat AMCs exposed to chronic hypoxia. In rat adrenal glands, BDNF and its tropomyosin‐related kinase B (TrkB) receptor are highly expressed in the cortex and medulla, respectively. Exposure of AMCs to chronic hypoxia (2% O2; 48 h) in vitro caused a significant increase to TrkB mRNA expression. A similar increase was observed in an immortalized chromaffin cell line (MAH cells); however, it was absent in MAH cells deficient in the transcription factor HIF‐2α. A specific TrkB agonist, 7,8‐dihydroxyflavone (7,8‐DHF), stimulated quantal catecholamine secretion from chronically hypoxic (CHox; 2% O2) AMCs to a greater extent than normoxic (Nox; 21% O2) controls. Activation of TrkB by BDNF or 7,8‐DHF increased intracellular Ca2+ ([Ca2+]i), an effect that was significantly larger in CHox cells. The 7,8‐DHF‐induced [Ca2+]i rise was sensitive to the tyrosine kinase inhibitor K252a and nickel (2 mm), but not the Ca2+ store‐depleting agent cyclopiazonic acid. Blockade of T‐type calcium channels with TTA‐P2 (1 μm) or voltage‐gated Na+ channels with TTX inhibited BDNF‐induced [Ca2+]i increases. BDNF also induced a dose‐dependent enhancement of action potential firing in CHox cells. These data demonstrate that during chronic hypoxia, enhancement of BDNF‐TrkB signalling increases voltage‐dependent Ca2+ influx and catecholamine secretion in chromaffin cells, and that T‐type Ca2+ channels play a key role in the signalling pathway.
Two key temporally distinguishable molecular and cellular components of white adipose tissue browning during cold acclimation
Authors: Jankovic Aleksandra , Golic Igor , Markelic Milica , Stancic Ana , Otasevic Vesna , Buzadzic Biljana , Korac Aleksandra , Korac Bato 
Published: June 2015

Key points
White to brown adipose tissue conversion and thermogenesis can be ignited by different conditions or agents and its sustainability over the long term is still unclear.
Browning of rat retroperitoneal white adipose tissue (rpWAT) during cold acclimation involves two temporally apparent components: (1) a predominant non‐selective browning of most adipocytes and an initial sharp but transient induction of uncoupling protein 1, peroxisome proliferator‐activated receptor (PPAR) coactivator‐1α, PPARγ and PPARα expression, and (2) the subsistence of relatively few thermogenically competent adipocytes after 45 days of cold acclimation.
The different behaviours of two rpWAT beige/brown adipocyte subsets control temporal aspects of the browning process, and thus regulation of both components may influence body weight and the potential successfulness of anti‐obesity therapies.
AbstractConversion of white into brown adipose tissue may have important implications in obesity resistance and treatment. Several browning agents or conditions ignite thermogenesis in white adipose tissue (WAT). To reveal the capacity of WAT to function in a brownish/burning mode over the long term, we investigated the progression of the rat retroperitoneal WAT (rpWAT) browning during 45 days of cold acclimation. During the early stages of cold acclimation, the majority of rpWAT adipocytes underwent multilocularization and thermogenic‐profile induction, as demonstrated by the presence of a multitude of uncoupling protein 1 (UCP1)‐immunopositive paucilocular adipocytes containing peroxisome proliferator‐activated receptor (PPAR) coactivator‐1α (PGC‐1α) and PR domain‐containing 16 (PRDM16) in their nuclei. After 45 days, all adipocytes remained PRDM16 immunopositive, but only a few multilocular adipocytes rich in mitochondria remained UCP1/PGC‐1α immunopositive. Molecular evidence showed that thermogenic recruitment of rpWAT occurred following cold exposure, but returned to starting levels after cold acclimation. Compared with controls (22 ± 1°C), levels of UCP1 mRNA increased in parallel with PPARγ (PPARα from days 1 to 7 and PGC‐1α on day 1). Transcriptional recruitment of rpWAT was followed by an increase in UCP1 protein content (from days 1 to 21). Results clearly showed that most of the adipocytes within rpWAT underwent transient brown‐fat‐like thermogenic recruitment upon stimulation, but only a minority of cells retained a brown adipose tissue‐like phenotype after the attainment of cold acclimation. Therefore, browning of WAT is dependent on both maintaining the thermogenic response and retaining enough brown‐like thermogenically competent adipocytes in the long‐term. Both aspects of browning could be important for long‐term energy homeostasis and body‐weight regulation.
Comparison of breast specific gamma imaging and molecular breast tomosynthesis in breast cancer detection: Evaluation in phantoms
Authors: Gong Zongyi , Williams Mark B. 
Published: June 2015

Purpose:Breast specific gamma imaging or molecular breast imaging (BSGI) obtains 2D images of 99mTc sestamibi distribution in the breast. Molecular breast tomosynthesis (MBT) maps the tracer distribution in 3D by acquiring multiple projections over a limited angular range. Here, the authors compare the performance of the two technologies in terms of spatial resolution, lesion contrast, and contrast‐to‐noise ratio (CNR) in phantom studies under conditions of clinically relevant sestamibi dose and imaging time.Methods:The systems tested were a Dilon 6800 and a MBT prototype developed at the University of Virginia. Both systems comprise a pixelated sodium iodide scintillator, an array of position sensitive photomultipliers, and a parallel hole collimator. The active areas and energy resolution of the systems are similar. System sensitivity, spatial resolution, lesion contrast, and CNR were measured using a Petri dish, a point source phantom, and a breast phantom containing simulated lesions at two depths, respectively. A single BSGI projection was acquired. Five MBT projections were acquired over ±20°. For both modalities, the total scan count density was comparable to that observed for each in typical 10 min human scans following injection of 22 mCi (814 MBq) of 99mTc‐sestamibi. To assess the impact of reducing the tracer dose, the pixel counts of projection images were later binomially subsampled by a factor of 2 to give images corresponding to an injected activity of approximately 11 mCi (407 MBq). Both unprocessed (pixelated) BSGI projections and interpolated (smoothed) BSGI images displayed by default on the Dilon 6800 workstation were analyzed. Volumetric images were reconstructed from the MBT projections using a maximum likelihood expectation maximization algorithm and extracted slices were analyzed.Results:Over a depth range of 1.5–7.5 cm, BSGI spatial resolution was 5.6–11.5 mm in unprocessed projections and 5.7–12.0 mm in interpolated images. Over the same range, the in‐slice MBT spatial resolution was 6.7–9.4 mm. Lesion contrast was significantly improved with MBT relative to BSGI for five out of eight lesions imaged at either the 22 mCi or the 11 mCi dose level (p < 0.05). At both dose levels, significant improvements in CNR with MBT were also found for five out of eight lesions (9.8, 7.8, 6.2 mm lesions at water depth of 1.7 cm and 9.8, 7.8 mm lesions at water depth of 4.5 cm, p < 0.05). The 6.2 and 4.9 mm lesions located at 4.5 cm below the water surface were not visible in either modality at either activity level.Conclusions:Under conditions of equal dose, imaging time and similar detectors, compared to BSGI, MBT provided higher lesion contrast, higher CNR, and spatial resolution that was less depth dependent.
Self-Efficacy Manipulation Influences Physical Activity Enjoyment in Chinese Adolescents
Authors: Hu Liang , Cheng Shoubin , Lu Jiaying , Zhu Lele , Chen Ling 
Published: June 2015

Purpose:In this study, we examined the effect of the manipulation of exercise self-efficacy on the enjoyment of physical activity in a sample of 44 Chinese adolescents (age = 14.27 ± .87 y), including 22 boys and 22 girls.Methods:The participants were randomized into a low-efficacy or high-efficacy condition, and their self-efficacy beliefs for engaging in moderate-intensity physical activity were manipulated by providing false feedback after a submaximal exercise test. The participants’ self-efficacy was measured and compared before and after the exercise test and the participants’ enjoyment of physical activity was assessed after the exercise test.Results:It was found that exercise self-efficacy was successfully manipulated in the expected direction in both conditions, which significantly influenced the participants’ enjoyment of physical activity. After the exercise test, the participants in the low-efficacy condition reported lower enjoyment scores relative to the high-efficacy participants.Conclusions:These results suggest that self-efficacy may have an important influence on the enjoyment of physical activity among Chinese adolescents. We recommend that physical activity promotion programs should be tailored to enhance adolescents’ self-efficacy beliefs and enjoyment of the experience of physical activity.
Genome Sequence of Mycobacteriophage Mindy
Authors: Pope Welkin H. , Bernstein Nicholas I. , Fasolas Christina S. , Mezghani Nadia , Pressimone Catherine A. , Selvakumar Priyanga , Stanton Ann-Catherine J. , Lapin Jonathan S. , Prout Ashley K. , Grubb Sarah R. , Warner Marcie H. , Bowman Charles A. , Russell Daniel A. , Hatfull Graham F. 
Published: June 2015

ABSTRACT

Mycobacteriophage Mindy is a newly isolated phage of
Mycobacterium smegmatis
, recovered from a soil sample in Pittsburgh, Pennsylvania, USA. Mindy has a genome length of 75,796 bp, encodes 147 predicted proteins and two tRNAs, and is closely related to mycobacteriophages in cluster E.
Draft Genome Sequence of Gluconobacter oxydans NL71, a Strain That Efficiently Biocatalyzes Xylose to Xylonic Acid at a High Concentration
Authors: Miao Yuanyuan , Zhou Xin , Xu Yong , Yu Shiyuan 
Published: June 2015

ABSTRACT

Gluconobacter oxydans
NL71, a selected strain in the crude lignocellulosic hydrolysate, catalyzed 600 g/liter xylose to 586.3 g/liter xylonic acid at 95.1% yield. The biocatalysis of xylose yielded three times higher than the best previous output, providing a possibility of the industrial scale utilization of lignocellulosic xylose. Due to its promising industrial applications, we sequenced the complete genome of strain
G. oxydans
NL71 to further our understanding of its overall metabolism.
Genome Sequence of
Porticoccus hydrocarbonoclasticus
Strain MCTG13d, an Obligate Polycyclic Aromatic Hydrocarbon-Degrading Bacterium Associated with Marine Eukaryotic Phytoplankton
Authors: Gutierrez Tony , Whitman William B. , Huntemann Marcel , Copeland Alex , Chen Amy , Kyrpides Nikos , Markowitz Victor , Pillay Manoj , Ivanova Natalia , Mikhailova Natalia , Ovchinnikova Galina , Andersen Evan , Pati Amrita , Stamatis Dimitrios , Reddy T. B. K. , Ngan Chew Yee , Chovatia Mansi , Daum Chris , Shapiro Nicole , Cantor Michael N. , Woyke Tanja 
Published: June 2015

ABSTRACT

Porticoccus hydrocarbonoclasticus
strain MCTG13d is a recently discovered bacterium that is associated with marine eukaryotic phytoplankton and that almost exclusively utilizes polycyclic aromatic hydrocarbons (PAHs) as the sole source of carbon and energy. Here, we present the genome sequence of this strain, which is 2,474,654 bp with 2,385 genes and has an average G+C content of 53.1%.
Full-Genome Sequence of the First G8P[14] Rotavirus Strain Detected in the United States
Authors: Mijatovic-Rustempasic Slavica , Roy Sunando , Sturgeon Michele , Rungsrisuriyachai Kunchala , Reisdorf Erik , Cortese Margaret M. , Bowen Michael D. 
Published: June 2015

ABSTRACT
This is a report of the complete genomic sequence of a rare rotavirus group A G8-P[14]-I2-R3-C2-M2-A3-N2-T6-E2-H3 strain detected in a stool sample from a 57-year-old subject.
High-intensity interval training for improving health-related fitness in adolescents: a systematic review and meta-analysis
Authors: Costigan S A , Eather N , Plotnikoff R C , Taaffe D R , Lubans D R 
Published: June 2015

BackgroundHigh-intensity interval training (HIIT) may be a feasible and efficacious strategy for improving health-related fitness in young people. The objective of this systematic review and meta-analysis was to evaluate the utility of HIIT to improve health-related fitness in adolescents and to identify potential moderators of training effects.MethodsStudies were considered eligible if they: (1) examined adolescents (13–18 years); (2) examined health-related fitness outcomes; (3) involved an intervention of ≥4 weeks in duration; (4) included a control or moderate intensity comparison group; and (5) prescribed high-intensity activity for the HIIT condition. Meta-analyses were conducted to determine the effect of HIIT on health-related fitness components using Comprehensive Meta-analysis software and potential moderators were explored (ie, study duration, risk of bias and type of comparison group).ResultsThe effects of HIIT on cardiorespiratory fitness and body composition were large, and medium, respectively. Study duration was a moderator for the effect of HIIT on body fat percentage. Intervention effects for waist circumference and muscular fitness were not statistically significant.ConclusionsHIIT is a feasible and time-efficient approach for improving cardiorespiratory fitness and body composition in adolescent populations.