Jens Jordan

German Aerospace Center (DLR) | DLR · Institute of Aerospace Medicine

ZUSAMMENFASSUNG Zwischen 1/15 000 und 1/50 000 Passagiere haben während eines Fluges akute medizinische Probleme, wobei Herzstillstände, die eine kardiopulmonale Wiederbelebung (CPR) erfordern, 0,3 % der medizinischen Notfälle ausmachen. Hypoxie in der Flugzeugkabine könnte die Sauerstoffversorgung und die körperliche Leistungsfähigkeit des Helfend...

Orthostatic hypertension, defined by an increase of systolic blood pressure (SBP) of ≥20 mmHg upon standing, harbors an increased cardiovascular risk. We pooled data from two rigorously conducted head-down tilt bedrest studies to test the hypothesis that cardiopulmonary deconditioning and hypovolemia predispose to orthostatic hypertension. With bed...

Prolonged immobilization and spaceflight cause cardiovascular and musculoskeletal deconditioning. Combining artificial gravity through short-arm centrifugation with rowing exercise may serve as a countermeasure. We aimed to compare the tolerability, muscle force production, cardiovascular response, and power output of rowing on a short-arm centrifu...

Objective Orthostatic hypertension defined as systolic blood pressure (SBP) increase of more than 20 mmHg when standing up with hypertensive upright SBP heralds increased cardiovascular risk. The phenomenon is caused by sympathetic overactivation and occurs in conditions associated with poor cardiopulmonary fitness or hypovolemia. We hypothesized t...

Objective In mice, prolonged exposure to severe ambient hypoxia promotes myocardial regeneration suggesting a novel treatment target for patients following myocardial infarction. However, hypoxia-induced pulmonary hypertension and myocardial ischemia are potential risks in human studies. Therefore, we conducted a pilot study in carefully selected p...

Objective Healthcare providers are faced with an increasing number of patients with obesity and arterial hypertension. Preventing obesity-associated hypertension and appropriately managing patients with established disease are both important. Hence, the aim of our study was to evaluate the clinical care of patients with obesity and hypertension amo...

Nutritional interventions and physical exercise are considered as basic therapy for obesity, but they cannot achieve sustained weight loss in many patients. Recently, several new drugs have been approved for supportive therapy in this indication. In addition to the intestinal lipase inhibitor orlistat, liraglutide and the combination of naltrexone...

Aerospace medicine required controlled terrestrial models to investigate influences of altered atmosphere conditions, such as hypoxia, on human health and performance. These models could potentially be expanded to encompass disease conditions or treatment targets regulated through hypoxia or hypercapnia. Hypoxia, a condition in which the body is de...

Zusammenfassung Die Luftfahrt gehört zu den am stärksten durch die COVID-19-Pandemie beeinträchtigten gesellschaftlichen Bereiche und hat gleichzeitig zu einer raschen globalen Ausbreitung des SARS-CoV-2-Virus beigetragen. SARS-CoV-2 gehört zu den Coronaviren, die schon in der Vergangenheit zu Ausbrüchen wie MERS-CoV geführt haben. Diese Erregergru...

Recent evidence suggests that an exaggerated blood pressure (BP) response to standing (ERTS) is associated with an increased risk of adverse outcomes, both in young and old individuals. In addition, ERTS has been shown to be an independent predictor of masked hypertension. In the vast majority of studies reporting on the prognostic value of orthost...

Background Healthcare providers are faced with an increasing number of patients with obesity and arterial hypertension. Preventing obesity-associated hypertension and appropriately managing patients with established disease are both important. Hence, the aim of our study was to evaluate the clinical care of patients with obesity and hypertension am...

The objective of this study was to assess whether dietary-induced weight loss improves myocardial deformation in people with overweight to obesity without established cardiovascular disease applying cardiovascular magnetic resonance (CMR) with feature tracking (FT) based strain analysis. Ninety people with overweight to obesity without established...

Aim Altered mitochondrial function across various tissues is a key determinant of spaceflight‐induced physical deconditioning. In comparison to tissue biopsies, blood cell bioenergetics holds promise as a systemic and more readily accessible biomarker, which was evaluated during head‐down tilt bed rest (HDTBR), an established ground‐based analog fo...

Background Solute carrier family 13 member 5 (SLC13A5) is a Na⁺-coupled citrate co-transporter that mediates entry of extracellular citrate into the cytosol. SLC13A5 inhibition has been proposed as a target for reducing progression of kidney disease. The aim of this study was to leverage the Mendelian randomization paradigm to gain insight into the...

Introduction Hypothalamic glucose-sensitive neural circuits, which regulate energy metabolism and can contribute to diseases such as obesity and type 2 diabetes, have been difficult to study in humans. We developed an approach to assess hypothalamic functional connectivity changes during glucose loading using functional magnetic resonance imaging (...

Reduced expression of the plasma membrane citrate transporter SLC13A5, also known as INDY, has been linked to increased longevity and mitigated age-related cardiovascular and metabolic diseases. Citrate, a vital component of the tricarboxylic acid cycle, constitutes 1–5% of bone weight, binding to mineral apatite surfaces. Our previous research hig...

Studies in mice with experimental myocardial infarction revealed, that sustained severe normobaric hypoxia (FiO2=0.07) reactivates cardiomyocyte proliferation and improves left ventricular ejection fraction. Our study aimed to test safety and feasibility in humans and to assess whether hypoxia improves left ventricular contractility in selected pat...

Impaired cardiovascular autonomic control following space flight or immobilization may limit the ability to cope with additional hemodynamic stimuli. Head-down tilt bedrest is an established terrestrial analog for space flight and offers the opportunity to test potential countermeasures for autonomic cardiovascular deconditioning. Previous studies...

The safety of prolonged high-altitude stays and exercise for physically fit post-myocardial infarction (MI) patients is unclear. Myocardial tissue hypoxia and pulmonary hypertension can affect cardiac function and electrophysiology, possibly contributing to arrhythmias. We included four non-professional male athletes, clinically stable after left v...

Acute exposure to hypoxia can lead to cognitive impairment. Therefore, hypoxia may become a safety concern for occupational or recreational settings at altitude. Cognitive tests are used as a tool to assess the degree to which hypoxia affects cognitive performance. However, so many different cognitive tests are used that comparing studies is challe...

Purpose To understand the influence of the coronavirus disease 2019 (COVID-19) pandemic on clinical autonomic education and research in Europe. Methods We invited 84 European autonomic centers to complete an online survey, recorded the pre-pandemic-to-pandemic percentage of junior participants in the annual congresses of the European Federation of...

The Artificial Gravity Bed Rest – European Space Agency (AGBRESA) study was the first joint bed rest study by ESA, DLR, and NASA that examined the effect of simulated weightlessness on the human body and assessed the potential benefits of artificial gravity as a countermeasure in an analog of long-duration spaceflight. In this study, we investigate...

Introduction Reductions in sympathetic nervous system activity may contribute to beneficial effects of sodium glucose cotransporter 2 (SGLT2) inhibition on cardiovascular outcomes. Therefore, we tested the hypothesis that SGLT2 inhibition with empagliflozin (Empa) lowers muscle sympathetic nerve activity (MSNA) in patients with type 2 diabetes mell...

In mice, hypoxia exposure corresponding to 8000 m altitude over several weeks induced myocardial proliferation and improved left ventricular ejection fraction following myocardial infarction. To enable translation of these findings from mice to patients with myocardial infarction, we determined whether exposure to severe sustained hypoxia is limite...

Background Solute carrier family 13 member 5 (SLC13A5) is a Na -coupled citrate co-transporter that mediates the entry of extracellular citrate into the cytosol. SLC13A5 inhibition has been proposed as a therapeutic target for reducing progression of kidney disease via its effects on citrate metabolism. However, evidence of its efficacy in humans i...

Background Prolonged immobilization and spaceflight lead to cardiovascular and musculoskeletal deconditioning. Combining artificial gravity through short-arm centrifugation with rowing exercise could serve as countermeasure. Our objective was to compare the tolerability, muscle force production, cardiovascular response, and potential power output o...

Introduction The ability to metabolize fructose to bypass the glucose pathway in near-anaerobic conditions appears to contribute to the extreme hypoxia tolerance of the naked-mole rats. Therefore, we hypothesized that exogenous fructose could improve endurance capacity and cognitive performance in humans exposed to hypoxia. Methods In a randomized...

Introduction Atrial natriuretic peptide (ANP), a hormone secreted from the heart, controls cardiovascular and renal functions including arterial blood pressure and natriuresis. ANP also exerts metabolic effects in adipose tissue, liver and skeletal muscle, and interacts with the secretion of adipokines. We tested the hypothesis that ANP lowers conc...

Purpose: Orthostatic intolerance commonly occurs following immobilization or space flight. We hypothesized that daily artificial gravity training through short-arm centrifugation could help to maintain orthostatic tolerance following head-down tilt bedrest, which is an established terrestrial model for weightlessness. Methods: We studied 24 heal...

Space medicine has developed controlled terrestrial models to investigate the impacts on human health and performance, and their application should be expanded to encompass disease conditions involving hypoxia and other factors, in order to make valuable contributions to clinical drug development. Hypoxia, a condition in which the body is deprived...

Document Reviewers Luis Alcocer (Mexico), Christina Antza (Greece), Mustafa Arici (Turkey), Eduardo Barbosa (Brazil), Adel Berbari (Lebanon), Luís Bronze (Portugal), John Chalmers (Australia), Tine De Backer (Belgium), Alejandro de la Sierra (Spain), Kyriakos Dimitriadis (Greece), Dorota Drozdz (Poland), Béatrice Duly-Bouhanick (France), Brent M. E...

ZUSAMMENFASSUNG Die Luftfahrt gehört zu den am stärksten durch die COVID-19-Pandemie beeinträchtigten gesellschaftlichen Bereiche und hat gleichzeitig zu einer raschen globalen Ausbreitung des SARS-CoV-2-Virus beigetragen. SARS-CoV-2 gehört zu den Coronaviren, die schon in der Vergangenheit zu Ausbrüchen wie MERS-CoV geführt haben. Diese Erregergru...

Objective In mice, normobaric hypoxia exposure corresponding to 8,000 m altitude after myocardial infarction reactivated cardiomyocyte proliferation and improved left ventricular ejection fraction (LVEF). Translating these findings to patients might be limited by hypoxia-induced pulmonary hypertension and myocardial ischemia. Design and method We...

Background Whether physically fit patients who have recovered from myocardial infarction can safely stay and exercise at high altitude is unclear. Myocardial tissue hypoxia and pulmonary hypertension could affect cardiac function, electrophysiology and predispose to arrythmias. Methods We included four non-professional male athletes (57.8 ± 3.3 ye...

Context: X-linked hypophosphatemia (XLH) is a rare genetic disease, characterized by renal phosphate wasting and complex musculoskeletal manifestations including decreased physical performance. Objective: To characterize muscular deficits in XLH patients and investigate phosphate stores of the muscle. Design: Case-control study (MuXLiH) with a...

Although we have sent humans into space for more than 50 years crucial questions regarding kidney physiology, volume regulation and osmoregulation remain unanswered. The complex interactions between the renin-angiotensin-aldosterone system, the sympathetic nervous system, osmoregulatory responses, glomerular function, tubular function, and environm...

The exact pathophysiology of the spaceflight-associated neuro-ocular syndrome (SANS) has so far not been completely elucidated. In this study we assessed the effect of acute head-down tilt position on the mean flow of the intra- and extracranial vessels. Our results suggest a shift from the external to the internal system that might play an importa...

Objective: To investigate the impact of the coronavirus-disease-2019 (COVID-19) pandemic on European clinical autonomic practice. Methods: Eighty-four neurology-driven or interdisciplinary autonomic centers in 22 European countries were invited to fill in a web-based survey between September and November 2021. Results: Forty-six centers comple...

Spaceflight and its associated stressors, such as microgravity, radiation exposure, confinement, circadian derailment and disruptive workloads represent an unprecedented type of exposome that is entirely novel from an evolutionary stand point. Within this perspective, we aimed to review the effects of prolonged spaceflight on immune-neuroendocrine...

The recent incidental discovery of an asymptomatic venous thrombosis (VT) in the internal jugular vein of an astronaut on the International Space Station prompted a necessary, immediate response from the space medicine community. The European Space Agency formed a topical team to review the pathophysiology, risk and clinical presentation of venous...

Introduction Mechanistic studies suggested that excess sympathetic activity promotes arterial hypertension while worsening insulin sensitivity. Older patients with type 2 diabetes are at particularly high cardiovascular and metabolic risk. However, data on sympathetic activity in this population is scarce. Methods We studied 61 patients with type...

A new consensus definition of orthostatic hypertension and the possible impact of this autonomic dysfunction on CV disease are discussed.

Cardiovascular diseases including arterial hypertension and congestive heart failure are often associated with an imbalance in cardiovascular autonomic control toward sympathetic predominance. Baroreflex activation could target the imbalance in cardiovascular autonomic control, and studies in the last years determined whether amplification of affer...

Background: Influenza seasonality has been frequently studied, but its mechanisms are not clear. Urban in-situ studies have linked influenza to meteorological or pollutant stressors. Few studies have investigated rural and less polluted areas in temperate climate AQ1 zones AQ2 . Objectives: We examined influences of medium-term residential exposure...

Influenza seasonality has been frequently studied, but its mechanisms are not clear. Urban in-situ studies have linked influenza to meteorological or pollutant stressors. Few studies have investigated rural and less polluted areas in temperate climate zones. We examined influences of medium-term residential exposure to fine particulate matter (PM2....

Purpose Arterial stiffness is independently associated with orthostatic hypotension in older individuals. The relationship between orthostatic blood pressure adaptation and aortic stiffness has not been thoroughly examined in a younger population. We investigated the relationship between orthostatic blood pressure adaptations, central aortic hemody...

We propose a consensus definition of "an exaggerated orthostatic pressor response" in subjects in whom systolic blood pressure increases ≥20 mmHg when going from the supine to standing posture. This definition can be extended for seated to standing measurements. We reserve the term "orthostatic hypertension" if this pressor response leads to an upr...

Background Discerning the mechanisms driving orthostatic symptoms in human beings remains challenging. Therefore, we developed a novel approach combining cardiac and cerebral real‐time magnetic resonance imaging, beat‐to‐beat physiological monitoring, and orthostatic stress testing through lower‐body negative pressure (LBNP). We conducted a proof‐o...

Patients with Fontan circulation are particularly dependent on low pulmonary vascular resistance because their lungs are passively perfused. Hypoxia drives pulmonary vasoconstriction; thus, red blood cell (RBC) deformability and stability of hematological parameters might be of particular importance, because alterations during hypoxia might further...

Purpose: Chronic exposure to hypoxia can induce muscle wasting in unaccustomed individuals. Detailed assessment of the effects of hypoxia on muscle tissue adaptation in elite mountaineers has not been performed. This study aims to monitor muscle volume after exposure to normobaric hypoxia. Methods: Two professional mountaineers (A and B) partici...

Desmin mutations cause familial and sporadic cardiomyopathies. In addition to perturbing the contractile apparatus, both desmin deficiency and mutated desmin negatively impact mitochondria. Impaired myocardial metabolism secondary to mitochondrial defects could conceivably exacerbate cardiac contractile dysfunction. We performed metabolic myocardia...

Reduced-caloric intake lowers blood pressure through sympathetic inhibition, and worsens orthostatic tolerance within days. Conversely, hypercaloric nutrition augments sympathetic activity and blood pressure. Because dietary interventions could be applied in patients with syncope, we tested the hypothesis that short-term hypercaloric dieting improv...

Background In pulmonary arterial hypertension (PAH), there is an excessive respiratory drive, which leads to inefficient ventilation with subsequent hypocapnia. Changes in blood gas analysis (BGA) may correlate with symptom severity and outcome. Data on impact of targeted PAH therapy on BGA are scarce and it remains unclear if these values can be u...

We propose a consensus definition of “an exaggerated orthostatic pressor response” in subjects in whom systolic blood pressure increases ≥ 20 mmHg when going from supine to standing posture. This definition can be extended for seated to standing measurements. We reserve the term “orthostatic hypertension” for when this pressor response leads to an...

Objectives: To identify neurology-driven or interdisciplinary clinical autonomic nervous system (ANS) laboratories in Europe, describe their characteristics and explore regional differences. Methods: We contacted the European national ANS and neurological societies, as well as members of our professional network to identify clinical ANS laborato...

Background and purpose: Disorders of the autonomic nervous system (ANS) are common conditions, but it is unclear whether access to ANS healthcare provision is homogeneous across European countries. The aim of this study was to identify neurology-driven or interdisciplinary clinical ANS laboratories in Europe, describe their characteristics and expl...

A comprehensive strategy is required to mitigate risks to astronauts’ health, well-being, and performance. This strategy includes developing countermeasures to prevent or reduce adverse responses to the stressors astronauts encounter during spaceflight, such as weightlessness. Because artificial gravity (AG) by centrifugation simultaneously affects...

Spaceflight is associated with reduced antigravitational muscle activity, which results in trunk muscle atrophy and may contribute to post-flight postural and spinal instability. Exercise in artificial gravity (AG) performed via short-arm human centrifugation (SAHC) is a promising multi-organ countermeasure, especially to mitigate microgravity-indu...

Mammalian INDY (mINDY, NaCT, gene symbol SLC13A5) is a potential target for the treatment of metabolically associated fatty liver disease (MAFLD). This study evaluated the effects of a selective, cross-species active, non-competitive, non-substrate-like inhibitor of NaCT. First, the small molecule inhibitor ETG-5773 was evaluated for citrate and su...

Ernährungsinterventionen und körperliches Training gelten als Basistherapie der Adipositas, können jedoch bei vielen Patientinnen und Patienten keine anhaltende Gewichtsreduktion erreichen. Zur unterstützenden Therapie bei dieser Indikation wurden in der letzten Zeit einige Medikamente neu zugelassen. Neben dem intestinalen Lipaseinhibitor Orlistat...

Changes in sympathetic nervous system activity may contribute to beneficial effects of sodium glucose transporter (SGLT2) inhibition on cardiovascular outcomes. We hypothesized that SGLT inhibition with empagliflozin lowers sympathetic activity compared with hydrochlorothiazide (HCT) to discern SGLT2-specific actions from non-specific responses to...

Objective: Normobaric hypoxia induces pulmonary hypertension (PH) in healthy individuals and post-myocardial infarction (P-MI) patients. Depending on the size of the myocardial scar and the remaining left ventricular ejection fraction, P-MI patients are potentially more vulnerable to cardiac rhythm disorders than healthy individuals. Albeit of utm...

Background: Animal studies have elicited therapeutic potential of severe ambient hypoxia for neurodegenerative diseases. However, uncertainties exist relative to individual (mal-)adaption mechanisms of the brain to hypoxia. To investigate the effects of hypoxia on cognitive performance and cerebral morphology, two healthy professional mountaineers...

Die National Aeronautics and Space Administration (NASA) hat ein arbeitsmedizinisches Überwachungsprogramm ins Leben gerufen, um Astronautinnen und Astronauten systematisch auf Halsvenenthrombosen zu screenen. Ziel ist es, Risikofaktoren, Prävalenz und klinischen Verlauf von Halsvenenthrombosen im Weltraum möglichst genau zu charakterisieren. Die A...

BACKGROUND: Manually controlled docking of a spacecraft to a space station is an operational task that poses high demands on cognitive and perceptual functioning. Effective processing of visual information is crucial for success. Eye tracking can reveal the operator's attentional focus unobtrusively and objectively. Therefore, our aim was to test t...

The current COVID-19 pandemic has aggravated pre-existing oxygen supply gaps all over the world. In fact, oxygen shortages occurred in affluent areas with highly developed healthcare systems. The state-of-affairs created much suffering and resulted in potentially preventable deaths. Meanwhile, several international activities have been initiated to...

[This corrects the article DOI: 10.3389/fphys.2021.743876.].

Background: Pulse wave velocity independently predicts cardiovascular risk. Easy to use single cuff oscillometric methods are utilized in clinical practice to estimate pulse wave velocity. We applied the approach in master athletes to assess possible beneficial effects of lifelong exercise on vascular health. Furthermore, we compared single cuff me...

We assessed lower-limb geometry in adults with X-linked hypophosphatemia (XLH) and controls. We found large differences in multiple measures including femoral and tibial torsion, bowing and cross-sectional area and acetabular version and coverage which may contribute to clinical problems such as osteoarthritis, fractures and altered gait common in...

BACKGROUND: Peripheral carotid chemoreceptors, which raise sympathetic activation at the brainstem level, may be altered trough atmospheric condition and is further affected by weightlessness-induced neural plasticity. However, human peripheral chemoreflex regulation in the brainstem is poorly understood due to the lack of suitable methodologies. T...

Background: The recent discovery of a venous thrombosis in the internal jugular vein of an astronaut has highlighted the need to predict the risk of venous thromboembolism in otherwise healthy individuals (VTE) in space. Virchow’s triad defines the three classic risk factors for VTE: blood stasis, hypercoagulability, and endothelial disruption/dysf...

Decreased expression of the plasma membrane citrate transporter INDY (acronym I’m Not Dead, Yet) promotes longevity and protects from high-fat diet- and aging-induced metabolic derangements. Preventing citrate import into hepatocytes by different strategies can reduce hepatic triglyceride accumulation and improve hepatic insulin sensitivity, even i...

To improve quantification of individual responses to bed rest interventions, we analyzed peripheral quantitative computer tomography (pQCT) datasets of the lower leg of 76 participants, who took part in eight different bed rest studies. A newly developed statistical approach differentiated measurement uncertainty UMeas from between-subject-variatio...

The harsh environmental conditions in space, particularly weightlessness and radiation exposure, can negatively affect cardiovascular function and structure. In the future, preventive cardiology will be crucial in enabling safe space travel. Indeed, future space missions destined to the Moon and from there to Mars will create new challenges to card...

Background: The harsh environmental conditions during space travel, particularly weightlessness, impose a major burden on the human body including the cardiovascular system. Given its importance in adjusting the cardiovascular system to environmental challenges, the autonomic nervous system has been in the focus of scientists and clinicians involv...

Aim. Pulse wave velocity independently predicts cardiovascular risk. Easy to use single cuff oscillometric methods are utilized in clinical practice to estimate pulse wave velocity. We applied the approach in master athletes to assess possible beneficial effects of lifelong exercise on vascular health. Furthermore, we compared single cuff measureme...

The alpha-3 subunit is a crucial component of the ganglionic acetylcholine receptor. Indeed, pharmacological ganglionic blockade or antagonistic antibodies against the alpha-3 subunit virtually abolish postganglionic sympathetic and parasympathetic traffic in human beings. Mutations of the CHRNA3 gene encoding the alpha-3 subunit appear to be a rar...

Background: Patients diagnosed with the hypermobile Ehlers-Danlos syndrome often experience orthostatic intolerance, particularly the postural tachycardia syndrome (POTS). To discern hemodynamic mechanisms limiting orthostatic tolerance in these patients, we applied a novel approach combining real-time magnetic resonance imaging (MRI), physiologica...

Background: Autonomic cardiovascular regulation is impaired both after bedrest and after space flight. Impaired autonomic control likely limits cardiovascular adaptation to physiological stresses such as standing. We hypothesized that 6 h daily lower body negative pressure (LBNP) helps maintain heart rate (HR), heart rate variability (HRV) and baro...