Introduction: The Metabolic Syndrome (MetS) describes the clustering of cardio-metabolic risk factors—including abdominal obesity, insulin resistance, elevated blood pressure, high levels of triglycerides, and low levels of high-density lipoproteins—that increase the risk for developing cardiovascular diseases and type 2 diabetes mellitus. However, a generally accepted definition of MetS in pediatric patients is still lacking.Objectives: The aim was to summarize current prevalence data of childhood MetS as well as to discuss the continuing disagreement between different pediatric definitions and the clinical importance of such diagnosis.Methodology: A systematic literature search on the prevalence of pediatric MetS was conducted. Articles that were published during the past 5 years (2014–2019), using at least one of four predetermined classifications (International Diabetes Federation, Cook et al., Ford et al., and de Ferranti et al.), were included.Results: The search resulted in 1167 articles, of which 31 publications met all inclusion criteria.Discussion: The prevalence of MetS ranged between 0.3 and 26.4%, whereby the rising number of children and adolescents with MetS partly depended on the definition used. The IDF definition generally provided the lowest prevalences (0.3–9.5%), whereas the classification of de Ferranti et al. yielded the highest (4.0–26.4%). In order to develop a more valid definition, further research on long-term consequences of childhood risk factors such as abdominal obesity, insulin resistance, hypertension, and dyslipidemia is needed. There is also a temptation to suggest one valid, globally accepted definition of metabolic syndrome for pediatric populations but we believe that it is more appropriate to suggest definitions of MetS that are specific to males vs. females, as well as being specific to race/ethnicity or geographic region. Finally, while this notion of definitions of MetS specific to certain subgroups is important, it still needs to be tested in future research.

People from low- and middle-income countries are disproportionately affected by the global burden of adverse health effects caused by ambient air pollution (AAP). However, data from Sub-Saharan Africa (SSA) are still scarce. We systematically reviewed the literature to describe the existing knowledge on AAP and health outcomes in SSA. We searched PubMed, Medline-OVID, EMBASE and Scopus databases to identify studies of AAP and health outcomes published up to November 15, 2017. We used a systematic review approach to critically analyze and summarize levels of outdoor air pollutants, and data on health effects associated with AAP. We excluded occupational and indoor exposure studies. We identified 60 articles, with 37 only describing levels of AAP and 23 assessing the association between air pollution and health outcomes. Most studies (75%) addressing the relation between AAP and disease were cross-sectional. In general, exposure data were only obtained for selected cities in the framework of temporary international collaborative research initiatives without structural long-term continuation. Measurements of AAP revealed 10-20 fold higher levels than WHO standards. Of the 23 studies reporting health effects, 14 originated from South Africa, and most countries within SSA contributed no data at all. No studies, except from South Africa, were based on reliable morbidity or mortality statistics at regional or country level. The majority of studies investigated self-reported respiratory symptoms. Children and the elderly were found to be more susceptible to AAP. AAP and its negative health effects have been understudied in SSA compared with other continents. The limited direct measurements of air pollutants indicate that AAP in SAA cities is high compared with international standards. Efforts are needed to monitor AAP in African cities, to identify its main sources, and to reduce adverse health effects by enforcing legislation.

Air pollution is a global health concern. Particulate matter (PM)_2.5, a component of ambient air pollution, has been identified by the World Health Organization as one of the pollutants that poses the greatest threat to public health. Cardiovascular health effects have been extensively documented, and these effects are still being researched to provide an overview of recent literature regarding air pollution-associated cardiovascular morbidity and mortality in humans. Additionally, potential mechanisms through which air pollutants affect the cardiovascular system are discussed based on human and additional animal studies. We used the strategy of a narrative review to summarize the scientific literature of studies that were published in the past 7 yr. Searches were carried out on PubMed and Web of Science using predefined search queries. We obtained an initial set of 800 publications that were filtered to 78 publications that were relevant to include in this review. Analysis of the literature showed significant associations between air pollution, especially PM_2.5, and the risk of elevated blood pressure (BP), acute coronary syndrome, myocardial infarction (MI), cardiac arrhythmia, and heart failure (HF). Prominent mechanisms that underlie the adverse effects of air pollution include oxidative stress, systemic inflammation, endothelial dysfunction, autonomic imbalance, and thrombogenicity. The current review underscores the relevance of air pollution as a global health concern that affects cardiovascular health. More rigorous standards are needed to reduce the cardiovascular disease burden imposed by air pollution. Continued research on the health impact of air pollution is needed to provide further insight.

This paper provides a general overview of key physiological consequences of microgravity experienced during spaceflight and of important parallels and connections to the physiology of the aging. Microgravity during spaceflight influences cardiovascular function, cerebral autoregulation, musculoskeletal and sensorimotor system performance. A great deal of research has been carried out to understand these influences and to provide countermeasures to reduce the observed negative consequences of microgravity on physiological function. Important and enlightening parallels can be drawn between deterioration of physiological function due to aging and negative consequences of microgravity. For example, head-down bedrest is used as a model to study effects of spaceflight deconditioning due to reduced gravity. As older persons spend up to 80% of their time in hospital bed-immobilized, the deconditioning effects of bedrest confinement on physiological functions and parallels with spaceflight deconditioning can be exploited to understand both variations of deconditioning. Deconditioning due to bed confinement during hospitalization is a major factor in physiological deconditioning, especially in older persons, and can contribute to a downward spiral of increasing frailty, orthostatic intolerance, falls and fall-related injury. As astronauts in space spend substantial amounts of time carrying out exercise training to counteract the microgravity-induced deconditioning and to counteract orthostatic intolerance on return to Earth, it is logical to suggest some of these interventions for bed-immobilzed persons. Parallels between deconditioning due to reduced gravitational stress in space and during bed confinement can provide an integration of knowledge and method that incorporates aspects such as (mal-) nutrition, muscle strength and function, cardiovascular (de-) conditioning and cardio-postural interactions.The impact of such integration can lead to insights and methods of value to both space medicine and Geriatrics (Geriatrics meets spaceflight). For health care delivery to our aging population, improved approaches for carrying out early re-mobilization in bed-confined older persons can have a major impact in reducing the morbidity and the mortality associated with bedrest and in the costs related to aging care.

Goswami N, Loeppky JA, Hinghofer-Szalkay H. LBNP: past protocols and technical considerations for experimental design. Aviat Space Environ Med 2008; 79:459–71. Introduction: Lower body negative pressure (LBNP) has been used for decades to simulate orthostatic stress and the effects of blood loss in humans. Since the definitive review of LBNP in 1974, new applications have been developed and research has revealed conflicting cardiovascular and neurohormonal responses during and after LBNP. Methods: A search of the literature was conducted for 1964–2007 using the Web of Science and the search terms “cardiovascular system,” “orthostasis,” “spaceflight,” and “methodologies” to identify publications in English that describe human studies where LBNP was used to simulate orthostasis. Publications cited in the earlier review were excluded, leaving a total of 215 articles for consideration. Results: We divided the reported protocols into eight categories based on the pressure, pattern, and duration of the stimulus: 1) mild, constant, short; 2) mild, constant, long; 3) mild, ramp, short; 4) mild, ramp, long; 5) moderate-to-strong, constant, short; 6) moderate, constant, long; 7) moderate-to-strong, ramp, short; and 8) strong, ramp, long. The review showed that these protocols stimulate different reflexes and can be used to produce particular responses. Discussion: Based on the review, we developed guidelines for using LBNP in a predictable and reproducible manner. Variables that must be controlled include subject characteristics, procedures, and environmental conditions as well as specifications for the LBNP chamber and seal positioning. An understanding of the many technical details of such experiments and the nature of elicited cardiovascular and neurohormonal responses is required to design optimal protocols to address specific research questions.

Orthostatic challenge produced by upright posture may lead to syncope if the cardiovascular system is unable to maintain adequate brain perfusion. This review outlines orthostatic intolerance related to the aging process, long-term bedrest confinement, drugs, and disease. Aging-associated illness or injury due to falls often leads to hospitalization. Older patients spend up to 83% of hospital admission lying in bed and thus the consequences of bedrest confinement such as physiological deconditioning, functional decline, and orthostatic intolerance represent a central challenge in the care of the vulnerable older population. This review examines current scientific knowledge regarding orthostatic intolerance and how it comes about and provides a framework for understanding of (patho-) physiological concepts of cardiovascular (in-) stability in ambulatory and bedrest confined senior citizens as well as in individuals with disease conditions [e.g., orthostatic intolerance in patients with diabetes mellitus, multiple sclerosis, Parkinson's, spinal cord injury (SCI)] or those on multiple medications (polypharmacy). Understanding these aspects, along with cardio-postural interactions, is particularly important as blood pressure destabilization leading to orthostatic intolerance affects 3–4% of the general population, and in 4 out of 10 cases the exact cause remains elusive. Reviewed also are countermeasures to orthostatic intolerance such as exercise, water drinking, mental arithmetic, cognitive training, and respiration training in SCI patients. We speculate that optimally applied countermeasures such as mental challenge maintain sympathetic activity, and improve venous return, stroke volume, and consequently, blood pressure during upright standing. Finally, this paper emphasizes the importance of an active life style in old age and why early re-mobilization following bedrest confinement or bedrest is crucial in preventing orthostatic intolerance, falls and falls-related injuries in older persons.