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Topic Review
Ultra-Endurance Participation and Acute Kidney Injury
Increasingly popular, ultra-endurance participation exposes athletes to extremely high levels of functional and structural damage. Ultra-endurance athletes commonly develop acute kidney injury (AKI) and other pathologies harmful to kidney health. There is strong evidence that non-steroidal anti-inflammatory drugs, common amongst ultra-athletes, is linked to increased risk and severity of AKI and potentially ischaemic renal injury, i.e., acute tubular necrosis. Ultra-endurance participation also increases the risk of exertional rhabdomyolysis, exercise-associated hyponatremia, and gastrointestinal symptoms, interlinked pathologies all with potential to increase the risk of AKI. Hydration and fuelling both also play a role with the development of multiple pathologies and ultimately AKI, highlighting the need for individualised nutritional and hydration plans to promote athlete health. Faster athletes, supplementing nitrates, and being female also increase the risk of developing AKI in this setting.
  • 773
  • 12 Jan 2023
Topic Review
Transient Receptor Potential Ankyrin 1
The transient receptor potential ankyrin 1 (TRPA1), a member of the TRP superfamily of channels, is primarily localized in a subpopulation of primary sensory neurons of the trigeminal, vagal, and dorsal root ganglia, where its activation mediates neurogenic inflammatory responses. TRPA1 expression in resident tissue cells, inflammatory, and immune cells, through the indirect modulation of a large series of intracellular pathways, orchestrates a range of cellular processes, such as cytokine production, cell differentiation, and cytotoxicity. 
  • 768
  • 05 May 2022
Topic Review
Skeletal Muscle Regeneration in Cardiotoxin-Induced Muscle Injury
Skeletal muscle injuries occur frequently in daily life and exercise. Understanding the mechanisms of regeneration is critical for accelerating the repair and regeneration of muscle. The process of regeneration is similar in different mouse strains and is inhibited by aging, obesity, and diabetes. Exercise, microcurrent electrical neuromuscular stimulation, and mechanical loading improve regeneration. The mechanisms of regeneration are complex and strain-dependent, and changes in functional proteins involved in the processes of necrotic fiber debris clearance, M1 to M2 macrophage conversion, SC activation, myoblast proliferation, differentiation and fusion, and fibrosis and calcification influence the final outcome of the regenerative activity.
  • 762
  • 17 Nov 2022
Topic Review
Mitochondrial Aging and Natural Products with Protective Potential
It was found that mitochondrial activity decreases with aging and that degeneration is linked to the reductions in mitochondria, mRNA transcripts, protein expression, and mtDNA and increased oxidative stress. In particular, reduced protein synthesis hinders protein turnover. The inability to replace damaged proteins may explain why aging is related to reduced mitochondrial function. Mitochondria, the cellular organelles that produce most of the ATP, become dysfunctional during aging. This condition is coupled with inflammation, oxidative stress, and reduced cellular functionalities in every organ. Numerous genes have been linked to aging, with some favoring it (gerontogenes) and others blocking it (genes of longevity pathways). The desire for eternal youth is a constant in the history of humanity. The increased life expectancy in industrialized countries has unfortunately also led to a significant increase in the incidence of age-related diseases (ARDs) such as neurodegenerative diseases, diabetes, cardiovascular diseases, and cancers.
  • 750
  • 27 Dec 2022
Topic Review
Stellate Ganglia and Cardiac Sympathetic Overactivation
Heart failure (HF) is a major public health problem worldwide, especially coronary heart disease (myocardial infarction)-induced HF with reduced ejection fraction (HFrEF), which accounts for over 50% of all HF cases. An estimated 6 million American adults have HF. As a major feature of HF, cardiac sympathetic overactivation triggers arrhythmias and sudden cardiac death, which accounts for nearly 50–60% of mortality in HF patients. Regulation of cardiac sympathetic activation is highly integrated by the regulatory circuitry at multiple levels, including afferent, central, and efferent components of the sympathetic nervous system. Much evidence has confirmed the afferent and central neural mechanisms causing sympathoexcitation in HF. The stellate ganglion is a peripheral sympathetic ganglion formed by the fusion of the 7th cervical and 1st thoracic sympathetic ganglion. As the efferent component of the sympathetic nervous system, cardiac postganglionic sympathetic neurons located in stellate ganglia provide local neural coordination independent of higher brain centers. 
  • 749
  • 21 Nov 2022
Topic Review
Aquaporins in Mesenchymal Stem Cells
Aquaporins (AQPs) are a family of membrane water channel proteins that control osmotically-driven water transport across cell membranes. Recent studies have focused on the assessment of fluid flux regulation in relation to the biological processes that maintain mesenchymal stem cell (MSC) physiology. In particular, AQPs seem to regulate MSC proliferation through rapid regulation of the cell volume. Furthermore, several reports have shown that AQPs play a crucial role in modulating MSC attachment to the extracellular matrix, their spread, and migration. This review aims to describe the recent findings on AQPs role in MSCs physiology taking into account their reflex for potential applicatio in regenerative medicine.
  • 743
  • 24 Dec 2020
Topic Review
Exercise as a Peripheral Circadian Clock Resynchronizer
Circadian rhythms involve biological rhythms that work by the interaction of several exogenous and endogenous factors, which together influence behavior, physiology, and metabolic processes in order to maintain homeostasis. The suprachiasmatic nucleus (SCN), together with other autonomous clocks, present in virtually all cells of the body, is responsible for controlling the central and peripheral circadian rhythm. However, the so-called synchronizers (also known as “zeitgebers”), such as external factors, can influence the functioning of these rhythms. The main synchronizer for SCN is the light–dark cycle that, through the retinohypothalamic tract, provides information to the SCN, which, by means of neurohumoral signaling and core body temperature oscillating, leads to the synchronization of peripheral clocks. However, there are also non-photic synchronizers such as food, physical activity, and stress.
  • 741
  • 06 Jan 2022
Topic Review
Manipulating Dream Experience
Dreaming, or sleep mentation, is an intriguing experience occurring during any human sleep stages. It can happen many times per night and is characterized by different degrees of emotional intensity, bizarreness, visual vividness, and narrative complexity. Mental activity during sleep and wakefulness shared similar neural bases. On the other side, recent studies have highlighted that dream experience is promoted by significant brain activation, characterized by reduced low frequencies and increased rapid frequencies. Additionally, several studies confirmed that the posterior parietal area and prefrontal cortex are responsible for dream experience.
  • 740
  • 22 May 2023
Topic Review
Episodic Memory Performance
The aim of this entry was to investigate whether oxygen is a rate limiting factor for any of the main cognitive domains in healthy young individuals. Subjects were randomly assigned to either increased oxygen supply using hyperbaric oxygen (two atmospheres of 100% oxygen) or to a “sham” treatment (simulation of increased pressure in the chamber breathing normal air). While in the chamber, participants went through a battery of tests evaluating the major cognitive domains including information processing speed, episodic memory, working memory, cognitive flexibility, and attention. The results demonstrated that from all evaluated cognitive domains, a statistically significant improvement was found in the episodic memory of the hyper-oxygenized group. The hyper-oxygenized group demonstrated a better learning curve and a higher resilience to interference. The results of this study indicate that memory function is a continuum that does not reach its maximal ceiling effect at the normal sea level environment even in healthy young individuals. Understanding the biological limitation of our cognitive functions is important for future development of interventional tools that can be used in the daily clinical practice.
  • 738
  • 30 Sep 2021
Topic Review
Nitrosative Stress in Retinal Pathologies
Nitric oxide (NO) is a gas molecule with diverse physiological and cellular functions. In the eye, NO is used to maintain normal visual function as it is involved in photoreceptor light transduction. In addition, NO acts as a rapid vascular endothelial relaxant, is involved in the control of retinal blood flow under basal conditions and mediates the vasodilator responses of different substances such as acetylcholine, bradykinin, histamine, substance P or insulin. However, the retina is rich in polyunsaturated lipid membranes and is sensitive to the action of reactive oxygen and nitrogen species. Products generated from NO (i.e., dinitrogen trioxide (N2O3) and peroxynitrite) have great oxidative damaging effects. Oxygen and nitrogen species can react with biomolecules (lipids, proteins and DNA), potentially leading to cell death, and this is particularly important in the retina.
  • 737
  • 22 Sep 2021
Topic Review
Tissue Fibrosis
Tissue fibrosis is characterized by excessive deposition of extracellular matrix (ECM) components that result from the disruption of regulatory processes responsible for ECM synthesis, deposition, and remodeling. Fibrosis develops in response to a trigger or injury and can occur in nearly all organs of the body.
  • 727
  • 29 Oct 2021
Topic Review
Reactive Oxygen Species in the Brain
Reactive oxygen and nitrogen species are crucial contributors to the age-dependent decline in all tissues. Neural tissue, one of the main oxygen consumers in the mammalian body, is especially prone to reactive species-mediated damage. Brain cells, including neurons, astrocytes, and microglia, produce reactive oxygen species (ROS) by specific enzymatic systems, including complexes of the mitochondrial respiratory chain, multienzyme flavin-containing complexes, monoamine and xanthine oxidases, microglial and endothelial NADPH oxidases and cyclooxygenases in addition to non-enzymatic and potentially uncontrolled mechanisms of ROS production, such as autooxidation of quinones or other aromatic compounds. Nitric oxide produced by nitric oxide synthases powers the conversion of ROS into reactive nitrogen species (RNS). Both ROS and RNS play important signaling roles and are also capable of modifying other molecules such as proteins, nucleic and fatty acids, lipids and carbohydrates. The antioxidant system, comprising low molecular mass antioxidants (e.g., tocopherol, ascorbic acid and glutathione) and high molecular mass antioxidants such as enzymes (e.g., catalases, peroxidases, superoxide dismutases) and others, protects cells from potential damage caused by ROS or RNS. Powering antioxidant systems by NADPH provides neural tissue with defense against ROS but may also trigger ROS production by NADPH oxidases and cyclooxygenases. In turn, mitochondria start using ketone bodies as an energy source under certain conditions. Increased steady-state levels of ROS and RNS, along with the aforementioned ROS-modified molecules, activate the organisms’ immune system including brain’s microglia.
  • 727
  • 09 Nov 2021
Topic Review
Emotion Regulation and Sleep
Emotion regulation refers to the process by which an individual influences the nature of his or her emotions and how emotions are experienced and expressed. Sleep deprivation may even impede the effectiveness of adaptive emotion regulation, such as distraction and cognitive reappraisal, consequently impacting emotional well-being.
  • 719
  • 05 Jul 2022
Topic Review
Hypoxic/Thermal Stress in Fish Heart
Teleost fish are often regarded with interest for the remarkable ability of several species to tolerate even dramatic stresses, either internal or external, as in the case of fluctuations in O2 availability and temperature regimes. These events are naturally experienced by many fish species under different time scales, but they are now exacerbated by growing environmental changes. This further challenges the intrinsic ability of animals to cope with stress. The heart is crucial for the stress response, since a proper modulation of the cardiac function allows blood perfusion to the whole organism, particularly to respiratory organs and the brain. In cardiac cells, key signalling pathways are activated for maintaining molecular equilibrium, thus improving stress tolerance. In fish, the nitric oxide synthase (NOS)/nitric oxide (NO) system is fundamental for modulating the basal cardiac performance and is involved in the control of many adaptive responses to stress, including those related to variations in O2 and thermal regimes.
  • 717
  • 14 Sep 2021
Topic Review
The Clinical Significance of Cyclic Glycine-Proline
Cyclic Glycine-Proline and insulin-like growth factor binding protein (IGFBP)-3 collectively regulate the bioavailability of IGF-1. The molar ratio of cGP/IGF-1 represents the amount of bioavailable and functional IGF-1 in circulation. The cGP/IGF-1 molar ratio is low in patients with age-related conditions, including hypertension, stroke, and neurological disorders with cognitive impairment. Stroke patients with a higher cGP/IGF-1 molar ratio have more favorable clinical outcomes. The elderly with more cGP have better memory retention. An increase in the cGP/IGF-1 molar ratio with age is associated with normal cognition, whereas a decrease in this ratio with age is associated with dementia in Parkinson disease. In addition, cGP administration reduces systolic blood pressure, improves memory, and aids in stroke recovery. These clinical and experimental observations demonstrate the role of cGP in regulating IGF-1 function and its potential clinical applications in age-related brain diseases as a plasma biomarker for—and an intervention to improve—IGF-1 function.
  • 716
  • 07 Feb 2023
Topic Review
Rhythm Generation
Rhythms are essential to living beings. They allow fluxes to coordinate with one another. Rhythms, thereby, constitute an information system for body functions. Biosphere rhythmicity largely relates to geophysical oscillations. To ignore the latter also affects human health and performance.
  • 711
  • 01 Nov 2020
Topic Review
Rapamycin Signaling at Muscle Fiber Fate in Sarcopenia
Sarcopenia, the age-related decline of muscle mass and strength/function is a major risk factor for disability and loss of independence in late life. Studies have shown that behavioral interventions (e.g., physical activity, adapted nutrition) reduce the rate of muscle wasting during aging. However, an incomplete understanding of the mechanisms driving age-related muscle loss has hampered the development of effective drugs to prevent or treat sarcopenia. Altered muscle protein metabolism is considered to be one of the main factors underlying the development and progression of sarcopenia. While basal rates of muscle protein synthesis (MPS) and degradation (MPD) seem to be unaffected by age, the anabolic response to a variety of stimuli (e.g., exercise, nutrient ingestion) is blunted during aging. The mammalian target of rapamycin (mTOR) is a key regulator of muscle anabolic and catabolic pathways and, hence, a promising target for interventions against sarcopenia.
  • 702
  • 30 Nov 2022
Topic Review
Diets and Exercise-Induced Oxidative Stress
Exhaustive exercise can induce excessive generation of reactive oxygen species (ROS), which may enhance oxidative stress levels. Besides single dosages of antioxidants, whole diets rich in antioxidants are gaining more attention due to their practicality and multicomponent ingredients. 
  • 700
  • 29 Apr 2021
Topic Review
Mitochondrial Ca2+ Signaling and Bioenergetics in Alzheimer’s Disease
Alzheimer’s disease (AD) is a hereditary and sporadic neurodegenerative illness defined by the gradual and cumulative loss of neurons in specific brain areas. The processes that cause AD are still under investigation and there are no available therapies to halt it. Progress puts at the forefront the “calcium (Ca2+) hypothesis” as a key AD pathogenic pathway, impacting neuronal, astrocyte and microglial function. An increasing body of evidence points out the early and crucial role of cellular Ca2+ handling dysregulation in AD pathogenesis. Interestingly, Ca2+ is a key regulator of several mitochondrial functions, such as ATP production, and brain cells rely mostly on OXPHOS to match their energy demands.
  • 698
  • 09 Dec 2022
Topic Review
Mental States and Molecular Biology
Today, it is possible to investigate the biological paths and mechanisms that link mental life to biological life. Emotions, feelings, desires, and cognitions influence biological systems. In recent decades, psychoneuroendocrinoimmunology research has highlighted the routes linking the psyche–brain–immune systems. Recently, epigenetics research has shown the molecular mechanisms by which stress and mental states modulate the information contained in the genome.
  • 689
  • 09 May 2022
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