Effects of parabolic flight and spaceflight on the endocannabinoid system in humans

The endocannabinoid system (ECS) plays an important role in the regulation of physiological functions, from stress and memory regulation to vegetative control and immunity. The ECS is considered a central and peripheral stress response system to emotional or physical challenges and acts through endocannabinoids (ECs), which bind to their receptors inducing subsequent effecting mechanisms. In our studies, the ECS responses have been assessed through blood concentrations of the ECs anandamide and 2-arachidonoylglycerol. In parallel, saliva cortisol was determined and the degree of perceived stress was quantified by questionnaires. This report summarizes the reactivity of the ECS in humans subjected to brief periods of kinetic stress and weightlessness during parabolic flights and to prolonged stress exposure during life onboard the International Space Station (ISS). Both conditions resulted in a significant increase in circulating ECs. Under the acute stress during parabolic flights, individuals who showed no evidence of motion sickness were in low-stress conditions and had a significant increase of plasma ECs. In contrast, highly stressed individuals with severe motion sickness had an absent EC response and a massive increase in hypothalamic-pituitary-adrenal axis activity. Likewise, chronic but well-tolerated exposure to weightlessness and emotional and environmental stressors on the ISS for 6 months resulted in a sustained increase in EC blood concentrations, which returned to baseline values after the cosmonauts' return. These preliminary results suggest that complex environmental stressors result in an increase of circulating ECs and that enhanced EC signaling is probably required for adaptation and tolerance under stressful conditions

Motion sickness, stress and the endocannabinoid system

A substantial number of individuals are at risk for the development of motion sickness induced nausea and vomiting (N&V) during road, air or sea travel. Motion sickness can be extremely stressful but the neurobiologic mechanisms leading to motion sickness are not clear. The endocannabinoid system (ECS) represents an important neuromodulator of stress and N&V. Inhibitory effects of the ECS on N&V are mediated by endocannabinoid-receptor activation

Predictive Capability of an iPad-Based Medical Device (medx) for the Diagnosis of Vertigo and Dizziness

Background:Making the correct diagnosis of patients presenting with vertigo and dizziness in clinical practice is often challenging. Objective:In this study we analyzed the usage of the iPad based program medx in the prediction of different clinical vertigo and dizziness diagnoses . We examined the power of medx to distinguish between different vertigo diagnoses. Patients and methods:The data collection was done in the outpatient clinic of the German Center of Vertigo and Balance Disorders. The “gold standard diagnosis” was defined as the clinical diagnosis of the specialist during the visit of the patient standardized history and clinical examination. Another independent and blinded physician finalized each patient’s case in constellatory diagnostic of medx by entering all available clinical information in the system. The accuracy, sensitivity, specificity as well as positive and negative predictive values for the most common diagnoses were determined. Sixteen possible different vertigo and dizziness diagnoses could be provided by medx constellatory diagnostic system. These diagnoses were compared to the “gold standard” by retrospective review of the charts of the patients over the study period. Results:610 patients (mean age58.1±16.3 years, 51.2 female) were included. The accuracy for the most common diagnoses was between 82.1- 96.6 with a sensitivity from 40- 80.5 and a specificity of more than 80. When analyzing the quality of medx in a multiclass-problem for the six most common clinical diagnoses the sensitivity, specificity, positive and negative predictive value were as follows: Bilateral vestibulopathy (81.6, 97.1, 71.1, 97.5), Menière's disease (77.8, 97.6, 87., 95.3), benign paroxysmal positional vertigo (61.7, 98.3, 86.6, 93.4), downbeat nystagmus syndrome (69.6, 97.7, 71.1, 97.5), vestibular migraine (34.7, 97.8, 76.1, 88.3) and phobic postural vertigo (80.5, 82,5, 52.5, 94.6), Conclusions:This study demonstrates that medx is a new and easy approach to screen for different diagnoses. With the high specificity and high negative predictive value the system helps to rule out differential diagnoses and can therefore also lead to a cost reduction in health care system. However, the sensitivity was unexpectedly low, especially for vestibular migraine. All in all, this device can only be a complementary tool, in particular for non-experts in the field

SARS-CoV-2 pneumonia and bacterial pneumonia patients differ in a second hit immune response model

Secondary infections have been shown to complicate the clinical course and worsen the outcome of critically ill patients. Severe Coronavirus Disease 2019 (COVID-19) may be accompanied by a pronounced cytokine release, and immune competence of these patients towards most pathogenic antigens remains uncompromised early in the disease. Patients with bacterial sepsis also exhibit excessive cytokine release with systemic hyper-inflammation, however, typically followed by an anti-inflammatory phase, causing immune paralysis. In a second hit immune response model, leukocyte activation capacity of severely ill patients with pneumonia caused by SARS-CoV-2 or by bacteria were compared upon ICU admission and at days 4 and 7 of the ICU stay. Blood cell count and release of the pro-inflammatory cytokines IL-2, IFNγ and TNF were assessed after whole-blood incubation with the potent immune stimulus pokeweed mitogen (PWM). For comparison, patients with bacterial sepsis not originating from pneumonia, and healthy volunteers were included. Lymphopenia and granulocytosis were less pronounced in COVID-19 patients compared to bacterial sepsis patients. After PWM stimulation, COVID-19 patients showed a reduced release of IFNγ, while IL-2 levels were found similar and TNF levels were increased compared to healthy controls. Interestingly, concentrations of all three cytokines were significantly higher in samples from COVID-19 patients compared to samples from patients with bacterial infection. This fundamental difference in immune competence during a second hit between COVID-19 and sepsis patients may have implications for the selection of immune suppressive or enhancing therapies in personalized medicine

Psychiatric comorbidity and psychosocial impairment among patients with vertigo and dizziness

Background: Vertigo and dizziness are often not fully explained by an organic illness, but instead are related to psychiatric disorders. This study aimed to evaluate psychiatric comorbidity and assess psychosocial impairment in a large sample of patients with a wide range of unselected organic and non-organic (ie, medically unexplained) vertigo/dizziness syndromes. Methods: This cross-sectional study involved a sample of 547 patients recruited from a specialised interdisciplinary treatment centre for vertigo/dizziness. Diagnostic evaluation included standardised neurological examinations, structured clinical interview for major mental disorders (SCID-I) and self-report questionnaires regarding dizziness, depression, anxiety, somatisation and quality of life. Results: Neurological diagnostic workup revealed organic and non-organic vertigo/dizziness in 80.8% and 19.2% of patients, respectively. In 48.8% of patients, SCID-I led to the diagnosis of a current psychiatric disorder, most frequently anxiety/phobic, somatoform and affective disorders. In the organic vertigo/dizziness group, 42.5% of patients, particularly those with vestibular paroxysmia or vestibular migraine, had a current psychiatric comorbidity. Patients with psychiatric comorbidity reported more vertigo-related handicaps, more depressive, anxiety and somatisation symptoms, and lower psychological quality of life compared with patients without psychiatric comorbidity. Conclusions: Almost half of patients with vertigo/dizziness suffer from a psychiatric comorbidity. These patients show more severe psychosocial impairment compared with patients without psychiatric disorders. The worst combination, in terms of vertigo-related handicaps, is having non-organic vertigo/dizziness and psychiatric comorbidity. This phenomenon should be considered when diagnosing and treating vertigo/dizziness in the early stages of the disease

PlanHab Study: Consequences of combined normobaric hypoxia and bed rest on adenosine kinetics

Adenosine plays a role in the energy supply of cells and provokes differential, hormone-like functions in circulating cells and various tissues. Its release is importantly regulated by oxygen tension. This renders adenosine and its kinetics interesting to investigate in humans subjected to low oxygen conditions. Especially for space exploration scenarios, hypoxic conditions - together with reduced gravity - represent two foreseen living conditions when planning manned long-duration space missions or planetary habitats. The PlanHab study investigated microgravity through inactivity in bed rest and normobaric hypoxia to examine their independent or combined effect on adenosine and its kinetics. Healthy male subjects (n = 14) completed three 21-day interventions: hypoxic bed rest (HBR); hypoxic ambulatory confinement (HAMB); normoxic bed rest (NBR). The interventions were separated by 4 months. Our hypothesis of a hypoxia-triggered increase in adenosine was confirmed in HAMB but unexpectedly also in NBR. However, the highest adenosine levels were noted following HBR. Furthermore, the percentage of hemolysis was elevated in HBR whereas endothelial integrity markers stayed low in all three interventions. In summary, these data suggest that neocytolysis accounts for these effects while we could reduce evidence for microcirculatory changes

Cells' Flow and Immune Cell Priming under alternating g-forces in Parabolic Flight

Gravitational stress in general and microgravity (mu g) in particular are regarded as major stress factors responsible for immune system dysfunction in space. To assess the effects of alternating mu g and hypergravity (hyper-g) on immune cells, the attachment of peripheral blood mononuclear cells (PBMCs) to adhesion molecules under flow conditions and the antigen-induced immune activation in whole blood were investigated in parabolic flight (PF). In contrast to hyper-g (1.8 g) and control conditions (1 g), flow and rolling speed of PBMCs were moderately accelerated during mu g-periods which were accompanied by a clear reduction in rolling rate. Whole blood analyses revealed a "primed" state of monocytes after PF with potentiated antigen-induced pro-inflammatory cytokine responses. At the same time, concentrations of anti-inflammatory cytokines were increased and monocytes displayed a surface molecule pattern that indicated immunosuppression. The results suggest an immunologic counterbalance to avoid disproportionate immune responses. Understanding the interrelation of immune system impairing and enhancing effects under different gravitational conditions may support the design of countermeasures to mitigate immune deficiencies in space

Cortical alterations in phobic postural vertigo - a multimodal imaging approach

Objective: Functional dizziness syndromes are among the most common diagnoses made in patients with chronic dizziness, but their underlying neural characteristics are largely unknown. The aim of this neuroimaging study was to analyze the disease-specific brain changes in patients with phobic postural vertigo (PPV). Methods: We measured brain morphology, task response, and functional connectivity in 44 patients with PPV and 44 healthy controls. Results: The analyses revealed a relative structural increase in regions of the prefrontal cortex and the associated thalamic projection zones as well as in the primary motor cortex. Morphological increases in the ventrolateral prefrontal cortex positively correlated with disease duration, whereas increases in dorsolateral, medial, and ventromedial prefrontal areas positively correlated with the Beck depression index. Visual motion stimulation caused an increased task-dependent activity in the subgenual anterior cingulum and a significantly longer duration of the motion aftereffect in the patients. Task-based functional connectivity analyses revealed aberrant involvement of interoceptive, fear generalization, and orbitofrontal networks. InterpretationOur findings agree with some of the typical characteristics of functional dizziness syndromes, for example, excessive self-awareness, anxious appraisal, and obsessive controlling of posture. This first evidence indicates that the disease-specific mechanisms underlying PPV are related to networks involved in mood regulation, fear generalization, interoception, and cognitive control. They do not seem to be the result of aberrant processing in cortical visual, visual motion, or vestibular regions