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The stress system coordinates the adaptive responses of the organism to stressors of any kind. 1 1 “Stress” is defined as a state of disharmony or threatened homeostasis. The concepts of stress and homeostasis can be traced back to ancient Greek history, however, the integration of these notions with related physiologic and pathophysiologic mechanisms and their association with specific illnesses are much more recent. In the present overview, we focus on the cellular and molecular infrastructure of the physiologic and behavioral adaptive responses to stress and we define the pathophysiologic effects of the dysregulation of the stress response, which may result in vulnerability to several disease entities, such as anxiety or depression and chronic inflammatory processes. The main components of the stress system are the corticotropin-releasing hormone (CRH) and locus ceruleus–norepinephrine (LC/NE)-autonomic systems and their peripheral effectors, the pituitary–adrenal axis, and the limbs of the autonomic system. Activation of the stress system leads to behavioral and peripheral changes that improve the ability of the organism to adjust homeostasis and increase its chances for survival. The CRH and LC/NE systems stimulate arousal and attention, as well as the mesocorticolimbic dopaminergic system, which is involved in anticipatory and reward phenomena, and the hypothalamic β-endorphin system, which suppresses pain sensation and, hence, increases analgesia. CRH inhibits appetite and activates thermogenesis via the catecholaminergic system. Also, reciprocal interactions exist between the amygdala and the hippocampus and the stress system, which stimulates these elements and is regulated by them. CRH plays an important role in inhibiting GnRH secretion during stress, while, via somatostatin, it also inhibits GH, TRH and TSH secretion, suppressing, thus, the reproductive, growth and thyroid functions. Interestingly, all three of these functions receive and depend on positive catecholaminergic input. The end-hormones of the hypothalamic–pituitary–adrenal (HPA) axis, glucocorticoids, on the other hand, have multiple roles. They simultaneously inhibit the CRH, LC/NE and β-endorphin systems and stimulate the mesocorticolimbic dopaminergic system and the CRH peptidergic central nucleus of the amygdala. In addition, they directly inhibit pituitary gonadotropin, GH and TSH secretion, render the target tissues of sex steroids and growth factors resistant to these substances and suppress the 5′ deiodinase, which converts the relatively inactive tetraiodothyronine (T4) to triiodothyronine (T3), contributing further to the suppression of reproductive, growth and thyroid functions. They also have direct as well as insulin-mediated effects on adipose tissue, ultimately promoting visceral adiposity, insulin resistance, dyslipidemia and hypertension (metabolic syndrome X) and direct effects on the bone, causing “low turnover” osteoporosis. Central CRH, via glucocorticoids and catecholamines, inhibits the inflammatory reaction, while directly secreted by peripheral nerves CRH stimulates local inflammation (immune CRH). CRH antagonists may be useful in human pathologic states, such as melancholic depression and chronic anxiety, associated with chronic hyperactivity of the stress system, along with predictable behavioral, neuroendocrine, metabolic and immune changes, based on the interrelations outlined above. Conversely, potentiators of CRH secretion/action may be useful to treat atypical depression, postpartum depression and the fibromyalgia/chronic fatigue syndromes, all characterized by low HPA axis and LC/NE activity, fatigue, depressive symptomatology, hyperalgesia and increased immune/inflammatory responses to stimuli.
A reduced-order modeling approach is proposed for the linear and nonlinear analysis of automated rack-supported warehouse (ARSW) structures under seismic loads. Steel ARSWs are massive structures that employ traditional racking configurations to support both the stored pallets and the external cladding shell. Capturing all the structural details of an ARSW requires tens or hundreds of thousands of elements, leading to complex numerical models that are analyzed with difficulty even in the linear range and are clearly unsuitable for nonlinear analysis. Thus, despite being prolific in earthquake-prone areas, their true seismic behavior remains largely untested. As a viable compromise between fidelity and low computational cost, we offer instead a reduced-order model that relies on the substitution of the one or more built-up columns (i.e., upright frames) with equivalent Timoshenko beam-column elements and two-node link elements. The resulting model can support both two-dimensional (2D) and three-dimensional (3D) elastic and inelastic analyses, offering a powerful tool for the seismic assessment of ARSWs and of complex structures comprising built-up columns in general.
<sec> <title>BACKGROUND</title> The World Health Organization named the phenomenon of misinformation spread through social media as an “<i>infodemic</i>” and recognized the need to curb it. Misinformation infodemics undermine not only population safety but also compliance to the suggestions and prophylactic measures recommended during pandemics. </sec> <sec> <title>OBJECTIVE</title> The aim of this pilot study is to review the impact of social media on general population fear in “<i>infoveillance</i>” studies during the COVID-19 pandemic. </sec> <sec> <title>METHODS</title> The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) protocol was followed, and 6 out of 20 studies were retrieved, meta-analyzed, and had their findings presented in the form of a forest plot. </sec> <sec> <title>RESULTS</title> The summary random and significant event rate was 0.298 (95% CI 0.213-0.400), suggesting that social media–circulated misinformation related to COVID-19 triggered public fear and other psychological manifestations. These findings merit special attention by public health authorities. </sec> <sec> <title>CONCLUSIONS</title> Infodemiology and infoveillance are valid tools in the hands of epidemiologists to help prevent dissemination of false information, which has potentially damaging effects. </sec>
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