China
Africa
Explore chapters and articles related to this topic
Age-Related Changes in the Autonomic Nervous System
Published in David Robertson, Italo Biaggioni, Disorders of the Autonomic Nervous System, 2019
Sheila M. Ryan, Lewis A. Lipsitz
Distinguishing the physiologic changes that influence autonomic function from specific diseases that are more common in advanced age presents particular complexities. Normal human aging is probably not associated with autonomic failure per se - since healthy people adapt well to physiological stress under usual circumstances. However selected areas of the autonomic nervous system do appear to undergo age-related changes. These changes result in a decline in autonomic reserve capacity during exposure to extreme levels of stress. The development of diseases and taking of various drugs in advanced age may also independently influence autonomic function, or may interact with age-related changes to seriously impair homeostatic capacity. This can result in symptomatic autonomic dysfunction. The increased prevalence of orthostatic and hypothermia in association with medications or comorbidity provide examples of this kind of interaction. Specific diseases of the autonomic nervous system, such as the Shy-Drager syndrome, are rare but occur more frequently in elderly people and require careful diagnosis and individualized treatment. These syndromes are discussed in other chapters.
Occupational and Environmental Lung Diseases
Published in James M. Rippe, Lifestyle Medicine, 2019
Sunkaru Touray, Emil Tigas, Nicholas A. Smyrnios
High-altitude illnesses (HAI) are a group of pulmonary and cerebral conditions that occur in the context of a rapid initial ascent to altitudes at a rate that exceeds the body’s ability to acclimatize to changes in oxygen tension. The fraction of oxygen in inspired air is constant at 0.21 regardless of altitude, but for each unit change in altitude, there is a non-linear change in the ba rometric pressure of oxygen that affects the alveolar partial pressure and consequently, oxygen availability to tissues. The physiologic response to this change in oxygen tension is called acclimatization and is characterized by changes in the heart rate, respiratory rate, chemoreceptor sensitivity to hypoxia, and pulmonary vasoconstriction. These act in concert to restore normal oxygen levels in tissues, but when the rate of altitude change exceeds the body’s homeostatic capacity, acute hypoxemia ensues, resulting in distinct clinical syndromes primarily affecting the lung and brain.
Raised Intracranial Pressure
Published in John W. Scadding, Nicholas A. Losseff, Clinical Neurology, 2011
The above components account for the initial part of the pressure–volume curve. In this part of the curve, increasing lesion volume leads to almost no increase in ICP. Once these rapid components of volume buffering are exhausted, however, the curve becomes progressively steeper, but the exact gradient depends on the speed of addition: rapid additional volume cannot be buffered adequately, but if the addition is sufficiently slow, the extracellular space is capable of shrinking by about 50 per cent, giving considerable additional homeostatic capacity.
Shifting the Focus of Dementia Prevention: Ethical Considerations
Published in AJOB Neuroscience, 2021
Alessandro Blasimme, Marco Canevelli, Matteo Cesari
Intrinsic capacity is currently understood as a five-domain construct comprising: cognition, psychological aspects, locomotion, sensory functions (in particular, vision and hearing), and vitality (i.e., metabolic/homeostatic capacity). In this context, preventive interventions can be understood as aimed at the preservation of the aging person's functional ability. We propose to call this approach ‘ground-state prevention' (GSP) to distinguish it from established models of prevention (Blasimme 2021). In particular, GSP differs from primary prevention in that it does not focus on disease-specific risk factors. It also differs from secondary prevention because it does not focus on early diagnosis of a given disease. Furthermore, unlike tertiary prevention, GSP is not intended to alleviate the burden of one specific condition alone.
Tackling pharmacological response heterogeneity by PBPK modeling to advance precision medicine productivity of nanotechnology and genomics therapeutics
Published in Expert Review of Precision Medicine and Drug Development, 2019
Ioannis S. Vizirianakis, Androulla N. Miliotou, George A. Mystridis, Eleftherios G. Andriotis, Ioannis I. Andreadis, Lefkothea C. Papadopoulou, Dimitrios G. Fatouros
Heterogeneity of drug actions in the body and variability in clinical phenotypes were previously known as idiosyncratic phenomena in experimental and in vivo pharmacology. Differential pharmacological response represents the variability in the clinical phenotype profile and inter-individual heterogeneity in drug response behavior in populations, also posing significant societal clinical and financial burdens worldwide. Alternatively, heterogeneity is the response capacity of an organism representing an intrinsic behavior, by which biological systems execute their functions towards the various environmental stimuli at the molecular level. In any case, the accountability for the differential response seen in clinical practice, which is a fundamental issue, refers to the cellular, molecular, and genomic heterogeneity underlying the pathophysiological function where the therapeutic modality is designed to exert its pharmacological profile. Moreover, biological systems are dynamic in nature regarding time, adaptation and homeostatic capacity regulation. That implies that upon trying to exploit molecular knowledge therapeutically, the experimental pharmacological approaches must efficiently address such heterogeneity issues to achieve broad and improved clinical efficacy and safety outcomes by covering the various patient populations. The latter must be done through establishing ‘sophisticated neogenic’ pharmacological assays that are adjustable and capable of sensing the molecular heterogeneity of biological systems in real-time, present accuracy and reproducibility of population pharmacokinetics’ nature, and are broadly compliant to regulatory issues worldwide.
Serum sodium level variability as a prognosticator in older adults
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2018
Maryam A. Barma, Roy L. Soiza, Peter T. Donnan, Mark M. McGilchrist, Helen Frost, Miles D. Witham
Serum sodium is frequently measured in older people, both to assess acute and chronic illness, as well as to monitor hydration and medication side-effects (e.g. diuretics and renin-angiotensin-aldosterone system inhibitors). Serial sodium levels are, therefore, readily available in routinely collected clinical datasets, and disorders of sodium balance are seen with increasing frequency in older patients [8]. Quantifying these imbalances and variation could offer insight into an individual’s homeostatic capacity, and offer advantages over the routinely used, but sub-optimal, concept of ‘static’ biomarker readings, referring to single measurements.