Salivary total protein and experimental Coriolis sickness

What is nausea? A historical analysis of changing views

The connotation of "nausea" has changed across several millennia. The medical term 'nausea' is derived from the classical Greek terms ναυτια and ναυσια, which designated the signs and symptoms of seasickness. In classical texts, nausea referred to a wide range of perceptions and actions, including lethargy and disengagement, headache (migraine), and anorexia, with an awareness that vomiting was imminent only when the condition was severe. However, some recent articles have limited the definition to the sensations that immediately precede emesis. Defining nausea is complicated by the fact that it has many triggers, and can build-up slowly or rapidly, such that the prodromal signs and symptoms can vary. In particular, disengagement responses referred to as the "sopite syndrome" are typically present only when emetic stimuli are moderately provocative, and do not quickly culminate in vomiting or withdrawing from the triggering event. This review considers how the definition of "nausea" has evolved over time, and summarizes the physiological changes that occur prior to vomiting that may be indicative of nausea. Also described are differences in the perception of nausea, as well as the accompanying physiological responses, that occur with varying stimuli. This information is synthesized to provide an operational definition of nausea.

Motion Sickness: Current Knowledge and Recent Advance

Motion sickness (MS) is a common physiological response to real or virtual motion. Numerous studies have investigated the neurobiological mechanism and the control measures of MS. This review summarizes the current knowledge about pathogenesis and pathophysiology, prediction, evaluation, and countermeasures of MS. The sensory conflict hypothesis is the most widely accepted theory for MS. Both the hippocampus and vestibular cortex might play a role in forming internal model. The pathophysiology focuses on the visceral afference, thermoregulation and MS-related neuroendocrine. Single-nucleotide polymorphisms (SNPs) in some genes and epigenetic modulation might contribute to MS susceptibility and habituation. Questionnaires, heart rate variability (HRV) and electrogastrogram (EGG) are useful for diagnosing and evaluating MS. We also list MS medications to guide clinical practice. Repeated real motion exposure and combined visual-vestibular interaction training accelerate the progress of habituation. Behavioral and dietary countermeasures, as well as physiotherapy, are also effective in alleviating MS symptoms.

Artificial G-load and chemical changes of saliva

Effectiveness of artificial G load is expected when it is used as a countermeasure against various bio-medical mishaps which are taking place in the micro-gravity environment, and probably more importantly, to prepare re-entry to the earth 1-G environment. Regarding the salivary chemical analysis, it has been known that, in case of (experimental) motion sickness, symptomatic outputs are delivered through the autonomic nervous system, and changes in salivary chemical components occur. In this study, accordingly, quantitative analyses of salivary potassium, sodium, chloride and total protein were performed before and after various levels of G loads which were produced by our short-radius human centrifuge. When the results were compared, the subjects who failed 60 minutes ride exhibited significantly higher post-load levels of potassium and sodium than those of successful 60 minutes riders. However, the differences between two groups were less clear in chloride and total protein. The result of present study indicates that salivary potassium and sodium are good indicators to represent autonomic nervous system function under the stressful condition produced by an artificial G load.