Browsing by Author "Goswami, Nandu"

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Arterial Stiffness in a Cohort of Young People Living With Perinatal HIV and HIV Negative Young People in England
(2022) Goswami, Nandu
Background: Antiretroviral therapy (ART) has increased life expectancy and consequently the risk of cardiovascular disease (CVD) in adults living with HIV. We investigated the levels and predictors of arterial stiffness in young people (YP) living with perinatal HIV (PHIV) and HIV negative YP in the Adolescents and Adults Living with Perinatal HIV (AALPHI) study. Methods: AALPHI was a prospective study evaluating the impact of HIV infection and exposure to ART on YP living with PHIV (aged 13–21 years) who had known their HIV status for at least 6 months, and HIV negative YP (aged 13–23 years) who either had a sibling, friend or parent living with HIV. Participants were enrolled from HIV clinics and community services in England. Two hundred and thirteen PHIV and 65 HIV negative YP (42% siblings of PHIV) had pulse wave velocity (PWV) measurements taken (Vicorder software) from the supra-sternal notch to the middle of the thigh cuff, at their second interview in the study between 2015 and 2017. Average PWV was calculated from the three closest readings (≥3 and ≤12 m/s) within 0.6 m/s of each other. Linear regression examined predictors of higher (worse) PWV, including age, sex, HIV status and height as a priori, ethnicity, born outside UK/Ireland, alcohol/nicotine/drug use, weight, waist-to-hip-ratio, mean arterial pressure (MAP), caffeine 2 h before PWV and nicotine on day of PWV. A separate PHIV model included CD4, viral load, years taking ART and ART regimen. Findings: One hundred and twenty eight (60%) PHIV and 45 (69%) HIV negative YP were female (p = 0.18), with median (IQR) age 18 (16, 20) and 18 (16, 21) years (p = 0.48) respectively. Most PHIV were taking a combination of three ART drugs from two classes. There was a trend toward higher (worse) mean PWV in the PHIV group than the HIV negative group [unvariable analysis 6.15 (SD 0.83) m/s vs. 5.93 (0.70) m/s, respectively, unadjusted p = 0.058], which was statistically significant in the multivariable analysis [adjusted p (ap) = 0.020]. In multivariable analysis Mellin et al. Arterial Stiffness in Young People being male (ap = 0.002), older age (ap < 0.001), higher MAP (ap < 0.001) and nicotine use on day of measurement (ap = 0.001) were also predictors of higher PWV. The predictors were the same in the PHIV model. Interpretation: By late adolescence PHIV had worse PWV in comparison to HIV negative peers, and traditional risk factors for CVD (higher arterial pressure, being male and older age) were associated with higher PWV values. Regular detailed monitoring of cardiovascular risk factors should become standard of care for every young person with PHIV worldwide.
Assessment of the Cardiovascular Risk Profile of Infants Exposed to Pre-eclampsia in-utero: A Prospective Case-Control Study in South African Children of African Ancestry
(2021) Goswami, Nandu
Background: It has been reported that maternal gestational environment may be programmed to have a significant impact on foetal and offspring health later in life. Studies have shown that children born to pre-eclamptic mothers are prone to obesity, hypertension, and diabetes in their adult life. However, such findings are yet to be established in an African population. This protocol is for a study aiming to investigate the relationship between pre-eclampsia (PE) and cardiovascular risk in children born to pre-eclamptic mothers in a South African population of African descents. Methods: A prospective case-control design will be employed to recruit pre-eclamptic and normotensive pregnant women and their offspring after birth. Pregnant women will be assessed for cardiovascular risk factors including PE, obesity, haemodynamics, lipids, glycaemic indices, oxidative stress, and vascular function at 30 weeks of gestation. The cardiovascular risk profile of their offspring will be assessed at birth and 6 weeks later. The difference in cardiovascular risk profile between children born to the pre-eclamptic and normotensive mothers will be compared and the correlation between maternal and offspring cardiovascular risks will be investigated. Discussion: This will be the first prospective study to assess the in-utero effect of cardiovascular risk in offspring born to pre-eclamptic women of African ancestry. It is expected that findings fromthis study will provide information on the cardiovascular effect of in-utero exposure to PE in a population of African ancestry. This knowledge will advise policy on the management of women with PE with a view of protecting cardiovascular health in offspring.
Assessment of the Performance of Obesity Measures in the Screening of Hypertension in a South African Adolescent Population
(2023) Goswami, Nandu
Abstract: Obesity is known to be one of the most significant risk factors for essential hypertension in childhood. However, whether obesity cut-offs may predict hypertension screening in adolescents remains controversial. This study investigated the performance of obesity cut-off values for the screening of hypertension in a South African adolescent population. In this cross-sectional study, 1144 adolescents aged between 11 and 17 years were recruited from the Eastern Cape Province of South Africa. Anthropometric and blood pressure (BP) parameters including diastolic blood pressure (DBP), systolic blood pressure (SBP), and heart rate (HR) were measured. Assessment of the sensitivity and specific of obesity cut-off values in predicting hypertension was performed using receiver operating characteristic (ROC) analysis. Obesity was positively associated (p < 0.01) with hypertension. Obese individuals, based on the predicted obesity using BMI percentile cut-off (pBMI85.2%), were more likely to develop hypertension (odds ratio: 2.070; p < 0.001) than their counterparts based on the observed obesity cut-off (pBMI95%) (Odd ratio: 1.748 p = 0.004). The area under the curve (AUC) of BMI percentile and WHtR for screening SBP percentile, and DBP percentile and HR as per ROC analysis, was low (<0.65). Equally, the sensitivity and specificity were low (<0.6) for all BP measures (SBP, DBP, and HR). Furthermore, the cut-off values for blood pressure measures, as established by ROC analysis using anthropometric measures, were far below the recommended cut-off values for hypertension screening. The obesity cut-offs for BMI percentile and WHtR established in this populations showed poor performance in diagnosing hypertension even though they were strong predictors of hypertension.
Author Correction: Systematic review of the use of ultrasound for venous assessment and venous thrombosis screening in spaceflight
(2024-02) Goswami, Nandu
Abstract: The validity of venous ultrasound (V-US) for the diagnosis of deep vein thrombosis (DVT) during spaceflight is unknown and difficult to establish in diagnostic accuracy and diagnostic management studies in this context. We performed a systematic review of the use of V-US in the upper-body venous system in spaceflight to identify microgravity-related changes and the effect of venous interventions to reverse them, and to assess appropriateness of spaceflight V-US with terrestrial standards. An appropriateness tool was developed following expert panel discussions and review of terrestrial diagnostic studies, including criteria relevant to crew experience, in-flight equipment, assessment sites, ultrasound modalities, and DVT diagnosis. Microgravity-related findings reported as an increase in internal jugular vein (IJV) cross-sectional area and pressure were associated with reduced, stagnant, and retrograde flow. Changes were on average responsive to venous interventions using lower body negative pressure, Bracelets, Valsalva and Mueller manoeuvres, and contralateral IJV compression. In comparison with terrestrial standards, spaceflight V-US did not meet all appropriateness criteria. In DVT studies (n = 3), a single thrombosis was reported and only ultrasound modality criterion met the standards. In the other studies (n = 15), all the criteria were appropriate except crew experience criterion, which was appropriate in only four studies. Future practice and research should account for microgravity-related changes, evaluate individual effect of venous interventions, and adopt Earth-based V-US standards.
Cardio-Metabolic Health of Offspring Exposed in Utero to Human Immuno-Deficiency Virus and Anti-Retroviral Treatment: A Systematic Review
(2023-12) Goswami, Nandu
Abstract: Background: Antiretroviral treatment (ART) use during pregnancy continues to rise as it is known to decrease the likelihood of HIV transmission from mother to child. However, it is still unknown whether foetal exposure to (ART) may affect the foetal environment, predisposing the offspring to cardiometabolic risk. Therefore, the aim of this study was to systematically review the cardio-metabolic effects of in utero exposure to HIV/ART on offspring. Methods: We carried out a systematic review and obtained literature from the Google scholar, PubMed, ProQuest, Web of Science, and Scopus databases. Two independent reviewers evaluated the titles, abstracts, and full-length English contents. Data from the eligible studies were included. Results: The search yielded 7596 records. After assessing all of these records, 35 of the full-length articles were included in this systematic review. Several studies showed that low birth weight, small head circumference, and altered mitochondrial content were more common among HIV-exposed uninfected (HEU) children compared to HIV-unexposed uninfected children (HUU). A few studies demonstrated elevated triglyceride levels, lower levels of insulin, and increased blood pressure, oxidative stress, vascular dysfunction, cardiac damage, and myocardial dysfunction among HEU children compared with HUU children. Conclusion: Most findings showed that there were cardio-metabolic health risk factors among HEU children, indicating that maternal exposure to HIV and ART may negatively affect foetal health, which may lead to cardio-metabolic morbidity later in life.
Compensatory hemodynamic changes in response to central hypovolemia in humans: lower body negative pressure: updates and perspectives
(2022-10) Goswami, Nandu
Abstract: Central hypovolemia is accompanied by hemodynamic compensatory responses. Understanding the complex systemic compensatory responses to altered hemodynamic patterns during conditions of central hypovolemia—as induced by standing up and/or lower body negative pressure (LBNP)—in humans are important. LBNP has been widely used to understand the integrated physiological responses, which occur during sit to stand tests (orthostasis), diferent levels of hemorrhages (diferent levels of LBNP simulate diferent amount of blood loss) as well as a countermeasure against the cephalad fuid shifts which are seen during spacefight. Additionally, LBNP application (used singly or together with head up tilt, HUT) is useful in understanding the physiology of orthostatic intolerance. The role seasonal variations in hormonal, autonomic and circulatory state play in LBNP-induced hemodynamic responses and LBNP tolerance as well as sex-based diferences during central hypovolemia and the adaptations to exercise training have been investigated using LBNP. The data generated from LBNP studies have been useful in developing better models for prediction of orthostatic tolerance and/or for developing countermeasures. This review examines how LBNP application infuences coagulatory parameters and outlines the efects of temperature changes on LBNP responses. Finally, the review outlines how LBNP can be used as innovative teaching tool and for developing research capacities and interests of medical students and students from other disciplines such as mathematics and computational biology.
Diversity of Hemodynamic Reactive Profiles across Persons—Psychosocial Implications for Personalized Medicine
(2022-07) Goswami, Nandu
Abstract: This study analyzed the individual differences in hemodynamic time patterns and reactivity to cognitive and emotional tasks, and explored the diversity of psycho-physiological profiles that could be used for the personalized prediction of different diseases. An analysis of heart rate (HR)— blood pressure (BP) relationship patterns across time using cross-correlations (CCs) during a logical mathematical task and a task recalling negative emotions (rumination) was carried out in a laboratory setting on 45 participants. The results showed maximum HR–BP CCs during the mathematical task significantly more positive than the maximum HR–BP CCs during the rumination task. Furthermore, our results showed a large variety of hemodynamic reactivity profiles across the participants, even when carrying out the same tasks. The most frequent type showed positive HR–BP CCs under cognitive activity, and several positive–negative HR–BP CCs cycles under negative emotional activity. In general terms, our results supported the main hypothesis. We observed some distinct time-based “coordination strategies” in the reactivity of the autonomic nervous system under emotional vs. cognitive loading. Overall, large individual, as well as situational, specificities in hemodynamic reactivity time patterns were seen. The possible relationships between this variety of profiles and different psychosocial characteristics, and the potential for integrative predictive health within the provision of highly personalized medicine, are discussed.
Effect of Microgravity Environment on Gut Microbiome and Angiogenesis
(2021) Goswami, Nandu
Abstract: Microgravity environments are known to cause a plethora of stressors to astronauts. Recently, it has become apparent that gut microbiome composition of astronauts is altered following space travel, and this is of significance given the important role of the gut microbiome in human health. Other changes observed in astronauts comprise reduced muscle strength and bone fragility, visual impairment, endothelial dysfunction, metabolic changes, behavior changes due to fatigue or stress and effects on mental well-being. However, the effects of microgravity on angiogenesis, as well as the connection with the gut microbiome are incompletely understood. Here, the potential association of angiogenesis with visual impairment, skeletal muscle and gut microbiome is proposed and explored. Furthermore, metabolites that are effectors of angiogenesis are deliberated upon along with their connection with gut bacterial metabolites. Targeting and modulating the gut microbiome may potentially have a profound influence on astronaut health, given its impact on overall human health, which is thus warranted given the likelihood of increased human activity in the solar system, and the determination to travel to Mars in future missions.
Effects of menstrual cycle on hemodynamic and autonomic responses to central hypovolemia
(2024-02) Shankhwar, Vishwajeet; Aljasmi, Khawla; Abdi, Asrar; Naser, Asmaa; Himeidi, Maya; Alsuwaidi, Hanan; Plessis, Stefan Du; Alsheikh-Ali, Alawi; Kellett, Catherine; Bayoumi, Riad; Goswami, Nandu
Abstract: Background: Estrogen and progesterone levels undergo changes throughout the menstrual cycle. Existing literature regarding the effect of menstrual phases on cardiovascular and autonomic regulation during central hypovolemia is contradictory. Aims and study: This study aims to explore the influence of menstrual phases on cardiovascular and autonomic responses in both resting and during the central hypovolemia induced by lower body negative pressure (LBNP). This is a companion paper, in which data across the menstrual phases from healthy young females, whose results are reported in Shankwar et al. (2023), were further analysed. Methods: The study protocol consisted of three phases: (1) 30 min of supine rest; (2) 16 min of four LBNP levels; and (3) 5 min of supine recovery. Hemodynamic and autonomic responses (assessed via heart rate variability, HRV) were measured before-, during-, and after-LBNP application using Task Force Monitor® (CNSystems, Graz, Austria). Blood was also collected to measure estrogen and progesterone levels. Results: In this companion paper, we have exclusively assessed 14 females from the previous study (Shankwar et al., 2023): 8 in the follicular phase of the menstrual cycle (mean age 23.38 ± 3.58 years, height 166.00 ± 5.78 cm, weight 57.63 ± 5.39 kg and BMI of 20.92 ± 1.96 25 kg/m2) and 6 in the luteal phase (mean age 22.17 ± 1.33 years, height 169.83 ± 5.53 cm, weight 62.00 ± 7.54 kg and BMI of 21.45 ± 2.63 kg/m2). Baseline estrogen levels were significantly different from the follicular phase as compared to the luteal phase: (33.59 pg/ml, 108.02 pg/ml, respectively, p < 0.01). Resting hemodynamic variables showed no difference across the menstrual phases. However, females in the follicular phase showed significantly lower resting values of low-frequency (LF) band power (41.38 ± 11.75 n.u. and 58.47 ± 14.37 n.u., p = 0.01), but higher resting values of high frequency (HF) band power (58.62 ± 11.75 n.u. and 41.53 ± 14.37 n.u., p = 0.01), as compared to females in the luteal phase. During hypovolemia, the LF and HF band powers changed only in the follicular phase F(1, 7) = 77.34, p < 0.0001 and F(1, 7) = 520.06, p < 0.0001, respectively. Conclusions: The menstrual phase had an influence on resting autonomic variables, with higher sympathetic activity being observed during the luteal phase. Central hypovolemia leads to increased cardiovascular and autonomic responses, particularly during the luteal phase of the menstrual cycle, likely due to higher estrogen levels and increased sympathetic activity.
Effects of space flight on sperm function and integrity: A systematic review
(2022-08) Ahrari, Khulood; Omolaoye, Temidayo S; Goswami, Nandu; Al Suwaidi, Hanan; Du Plessis, Stefan
Abstract: With the advancement in space exploration and the intention to establish an inhabitable human settlement on Mars, it is important to investigate the effects of exposure to space/microgravity and the associated radiations on procreation. Sperm function and integrity are fundamental to male reproduction and can potentially be affected by the environmental changes experienced in space. Therefore, this study was conducted to systematically gather, filter, and collate all the relevant information on the effects of spaceflight on male reproductive parameters and functions. A search was performed utilizing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data were extracted from the major electronic databases including PubMed, and other credible literature sources. MeSH search terms that were employed included "spermatozoa", "microgravity", and "ionizing radiation". The literature search did not discriminate against papers published before a certain date due to the very limited number of articles available. However, there was a restriction on the male gender and language (English). The parameters included in this study are sperm motility, total sperm count, sperm DNA fragmentation hormonal levels and testicular histology. Following a comprehensive literature search, a total of 273 articles were retrieved and screened, 252 articles were excluded due to the irrelevance to the topic, duplication, and non-original articles. A total of 21 articles met the inclusion criteria and are included in the current study. Findings from these studies showed that sperm motility was decreased after exposure to microgravity and ionizing radiation. Total sperm count was also found to be reduced by microgravity only. Sperm DNA fragmentation was increased by both ionizing radiation and microgravity. Testosterone levels and testicular weight were also decreased by microgravity. Although there is a dearth in the literature regarding the effects of microgravity and ionizing radiation on male reproductive parameters, the available findings showed that exposure to microgravity poses a risk to male reproductive health. Therefore, it is essential to develop countermeasures to either manage, treat, or prevent these consequential adverse effects. Hence, this review also highlights some potential countermeasure approaches that may mitigate the harmful effects of microgravity and associated exposures on male reproductive health.
Effects of whole-body vibration or resistive-vibration exercise on blood clotting and related biomarkers: a systematic review
(2023-11) Goswami, Nandu
Abstract: Whole-body vibration (WBV) and resistive vibration exercise (RVE) are utilized as countermeasures against bone loss, muscle wasting, and physical deconditioning. The safety of the interventions, in terms of the risk of inducing undesired blood clotting and venous thrombosis, is not clear. We therefore performed the present systematic review of the available scientific literature on the issue. The review was conducted following the guidelines by the Space Biomedicine Systematic Review Group, based on Cochrane review guidelines. The relevant context or environment of the studies was “ground-based environment”; space analogs or diseased conditions were not included. The search retrieved 801 studies; 77 articles were selected for further consideration after an initial screening. Thirty-three studies met the inclusion criteria. The main variables related to blood markers involved angiogenic and endothelial factors, fibrinolysis and coagulation markers, cytokine levels, inflammatory and plasma oxidative stress markers. Functional and hemodynamic markers involved blood pressure measurements, systemic vascular resistance, blood flow and microvascular and endothelial functions. The available evidence suggests neutral or potentially positive effects of short- and longterm interventions with WBV and RVE on variables related to blood coagulation, fibrinolysis, inflammatory status, oxidative stress, cardiovascular, microvascular and endothelial functions. No significant warning signs towards an increased risk of undesired clotting and venous thrombosis were identified. If confirmed by further studies, WBV and RVE could be part of the countermeasures aimed at preventing or attenuating the muscular and cardiovascular deconditioning associated with spaceflights, permanence on planetary habitats and ground-based simulations of microgravity.
Health and Academic Performance With Happy Children: A Controlled Longitudinal Study Based on the HOPP Project
(2022) Goswami, Nandu
Background: Overweight/obesity in children and adolescents, largely arising due to increased food intake and reduced physical activity, is a major health concern. Physical activity (PA) integrated into learning has been shown to not only lead to improved health outcomes and wellbeing but also positively affect academic performance. The Health and Academic Performance with Happy Children (HAPHC) project aims at enhancing health and academic performance in elementary school children via implementation of a daily unit of Physical Activity Across the Curriculum (PAAC), which is carried out within the school setting. In this project, PA as an integrated part of learning will be evaluated and the learning material adapted for a large scale implementation across several European countries. Methods: In three European countries (Austria, Slovenia, and Belgium), 12 primary schools in total will be recruited to act as either intervention or control school in a large intervention study, which applies the PAAC pedagogy during lectures. It is estimated that, at least 3,000+ children across the three countries will be recruited in this study. All teachers of intervention schools will receive training and materials/teaching equipment that will allow them to integrate a daily PA unit of 45 min over 3 years across the curriculum. In response to the daily PA intervention, the following primary outcomes will be assessed: changes in health related physiological factors, academic achievement, psycho-social aspects and wellbeing. Impact of Project: The HAPHC project aims at promoting public health by increasing PA at an early age within the school setting and therewith preventing the increasing risk of non-communicable diseases across Europe. HAPHC project aims to develop knowledge and materials, which will ensure that the PAAC can be scalable to other European countries.
Human physiology adaptation to altered gravity environments
(2021) Goswami, Nandu
Abstract: Multiple transitions between gravity levels will occur during planetary exploration missions. In reaction to these gravitational transitions, physiological adaptation will be initiated. However, the physiological effects of longduration exposures to hypogravity and hypergravity are poorly understood. In this review we present an overview of how humans perceive gravity, review sex-based differences in adaptation to changes in gravity, and introduces rather limited evidence currently available related to the effects of partial gravity. The paper then argues that there is a need for more research to better understand the extent and dynamics of physiological adaptation mechanisms during gravity level transitions in spaceflight and proposes a need for artificial gravity (AG) as a multi-system countermeasure and explore the efficacy of AG as countermeasure between short and very long-arm centrifuges. Discussed here are the effects of acute short-arm AG application. The topical review also discusses the usage of chronic AG application via the innovative large-radius Hypergravity Human Habitat, H3 , concept.
The kidney, volume homeostasis and osmoregulation in space: current perspective and knowledge gaps
(2023) Goswami, Nandu
Introduction: 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 environmental factors such as sodium and water intake, motion sickness and ambient temperature make it difficult to establish the exact effect of microgravity and the subsequent fluid shifts and muscle mass loss on these parameters. Unfortunately, not all responses to actual microgravity can be reproduced with head-down tilt bed rest studies, which complicates research on Earth. Better understanding of the effects of microgravity on kidney function, volume regulation and osmoregulation are needed with the advent of long-term deep space missions and planetary surface explorations during which orthostatic intolerance complaints or kidney stone formation can be life-threatening for astronauts. Galactic cosmic radiation may be a new threat to kidney function. In this review, we summarise and highlight the current understandings of the effects of microgravity on kidney function, volume regulation and osmoregulation and discuss knowledge gaps that future studies should address.
Pathophysiology, risk, diagnosis, and management of venous thrombosis in space: where are we now?
(2023) Goswami, Nandu
Introduction: A recent study investigating astronaut jugular venous flow inflight on the International Space Station (ISS) reported the incidental finding of a persistent asymptomatic obstructive left internal jugular (IJV) venous thrombosis (VT) in a single crewmember1. Furthermore, an additional suspected case was reported following retrospective analysis of the images from the other 11 crew members who participated in the study2 . Venous thrombi can lead to localised pain, redness, distal swelling, venous ischaemia, skin necrosis and even organ dysfunction3 . However, the most significant complication is lung embolization of thrombotic fragments, termed pulmonary embolism (PE) that can lead to cardiorespiratory insufficiency, which can be fatal. Thus, the potential identification of VT, a mission-critical medical condition, in such a highly selected, previously considered low-risk population is concerning and warrants urgent investigation. As a result, the European Space Agency (ESA) supported the creation in 2020 of a ‘Topical Team’ comprising of international subject matter experts in coagulation, venous thrombosis, prophylaxis, and treatment of thrombo-embolic events. The creation of this team was additionally supported by the Cardiovascular, Pulmonary, Renal and Lymphatic Working Group of the ESA SciSpacE roadmap. An operationally focused research strategy is required to define the pathophysiological processes leading to VT presentation in spaceflight, potential clinical presentation, its risk (and the factors that may affect risk), whilst proposing evaluation of candidate diagnostic, mitigation, and management strategies compatible with human spaceflight. The team was supported by individuals familiar with Human Spaceflight medical operations to identify relevant knowledge gaps.
A pilot study: Exploring the influence of COVID-19 on cardiovascular physiology and retinal microcirculation
(2023) Goswami, Nandu
Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affects the cardiovascular system. The current study investigated changes in heart rate (HR), blood pressure (BP), pulse wave velocity (PWV), and microcirculation in patients recovering from Coronavirus disease 2019 (COVID-19) infection. Methodology: Out of 43 initially contacted COVID-19 patients, 35 (30 males, 5 females; age: 60 ± 10 years; and body mass index (BMI): 31.8 ± 4.9) participated in this study. Participants were seen on two occasions after hospital discharge; the baseline measurements were collected, either on the day of hospital discharge if a negative PCR test was obtained, or on the 10th day after hospitalization if the PCR test was positive. The second measurements were done 60 days after hospitalization. The vascular measurements were performed using the VICORDER® device and a retinal blood vessel image analysis. Results: A significant increase in systolic BP (SBP) (from 142 mmHg, SD: 15, to 150 mmHg, SD: 19, p = 0.041), reduction in HR (from 76 bpm, SD: 15, to 69 bpm, SD: 11, p = 0.001), and narrower central retinal vein equivalent (CRVE) (from 240.94 μm, SD: 16.05, to 198.05 μm, SD: 17.36, p = 0.013) were found. Furthermore, the trends of increasing PWV (from 11 m/s, SD: 3, to 12 m/s, SD: 3, p = 0.095) and decreasing CRAE (from 138.87 μm, SD: 12.19, to 136.77 μm, SD: 13.19, p = 0.068) were recorded. Conclusion: The present study investigated cardiovascular changes following COVID-19 infection at two-time points after hospital discharge (baseline measurements and 60 days post-hospitalization). Significant changes were found in systolic blood pressure, heart rate, and microvasculature indicating that vascular adaptations may be ongoing even weeks after hospitalization from COVID-19 infection. Future studies could involve conducting additional interim assessments during the active infection and post-infection periods.
Retinal venular vessel diameters are smaller during ten days of bed rest
(2024) Goswami, Nandu
Introduction: Older individuals experience cardiovascular dysfunction during extended bedridden hospital or care home stays. Bed rest is also used as a model to simulate accelerated vascular deconditioning occurring during spacefight. This study investigates changes in retinal microcirculation during a tenday bed rest protocol. Ten healthy young males (22.9± 4.7 years; body mass index: 23.6± 2.5 kg·m–2) participated in a strictly controlled repeated-measures bed rest study lasting ten days. High-resolution images were obtained using a hand-held fundus camera at baseline, daily during the 10 days of bed rest, and 1 day after re-ambulation. Retinal vessel analysis was performed using a semi-automated software system to obtain metrics for retinal arteriolar and venular diameters, central retinal artery equivalent and central retinal vein equivalent, respectively. Data analysis employed a mixed linear model. At the end of the bed rest period, a signifcant decrease in retinal venular diameter was observed, indicated by a signifcantly lower central retinal vein equivalent (from 226.1 µm, CI 8.90, to 211.4 µm, CI 8.28, p= .026), while no signifcant changes in central retinal artery equivalent were noted. Prolonged bed rest confnement resulted in a signifcant (up to 6.5%) reduction in retinal venular diameter. These fndings suggest that the changes in retinal venular diameter during bedrest may be attributed to plasma volume losses and refect overall (cardio)-vascular deconditioning.
Search for Venous Endothelial Biomarkers Heralding Venous Thromboembolism in Space: A Qualitative Systematic Review of Terrestrial Studies
(2022) Goswami, Nandu
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/dysfunction. Among these risk factors, venous endothelial disruption/dysfunction remains incompletely understood, making it difficult to accurately predict risk, set up relevant prophylactic measures and initiate timely treatment of VTE, especially in an extreme environment. Methods: A qualitative systematic review focused on endothelial disruption/dysfunction was conducted following the guidelines produced by the Space Biomedicine Systematic Review Group, which are based on Cochrane review guidelines. We aimed to assess the venous endothelial biochemical and imaging markers that may predict increased risk of VTE during spaceflight by surveying the existing knowledge base surrounding these markers in analogous populations to astronauts on the ground. Results: Limited imaging markers related to endothelial dysfunction that were outside the bounds of routine clinical practice were identified. While multiple potential biomarkers were identified that may provide insight into the etiology of endothelial dysfunction and its link to future VTE, insufficient prospective evidence is available to formally recommend screening potential astronauts or healthy patients with any currently available novel biomarker. Conclusion: Our review highlights a critical knowledge gap regarding the role biomarkers of venous endothelial disruption have in predicting and identifying VTE. Future populationbased prospective studies are required to link potential risk factors and biomarkers for venous endothelial dysfunction to occurrence of VTE.
Sex Variations in Retinal Microcirculation Response to Lower Body Negative Pressure
(2023) Shankhwa, Vishwajeet; Goswami, Nandu
Introduction: Lower body negative pressure (LBNP) is routinely used to induce central hypovolemia. LBNP leads to a shift in blood to the lower extremities. While the effects of LBNP on physiological responses and large arteries have been widely reported, there is almost no literature regarding how these cephalad fluid shifts affect the microvasculature. The present study evaluated the changes in retinal microcirculation parameters induced by LBNP in both males and females. Methodology: Forty-four participants were recruited for the present study. The retinal measurements were performed at six time points during the LBNP protocol. To prevent the development of cardiovascular collapse (syncope) in the healthy participants, graded LBNP until a maximum of −40 mmHg was applied. A non-mydriatic, hand-held Optomed Aurora retinal camera was used to capture the retinal images. MONA Reva software (version 2.1.1) was used to analyze the central retinal arterial and venous diameter changes during the LBNP application. Repeated measures ANOVAs, including sex as the between-subjects factor and the grade of the LBNP as the within-subjects factor, were performed. Results: No significant changes in retinal microcirculation were observed between the evaluated time points or across the sexes. Conclusions: Graded LBNP application did not lead to changes in the retinal microvasculature across the sexes. The present study is the first in the given area that attempted to capture the changes in retinal microcirculation caused by central hypovolemia during LBNP. However, further research is needed with higher LBNP levels, including those that can induce pre-fainting (presyncope), to fully understand how retinal microcirculation adapts during complete cardiovascular collapse (e.g., during hypovolemic shock) and/or during severe hemorrhage.
Systematic review of the use of ultrasound for venous assessment and venous thrombosis screening in spaceflight
(2024-02) Goswami, Nandu
Abstract: The validity of venous ultrasound (V-US) for the diagnosis of deep vein thrombosis (DVT) during spaceflight is unknown and difficult to establish in diagnostic accuracy and diagnostic management studies in this context. We performed a systematic review of the use of V-US in the upper-body venous system in spaceflight to identify microgravity-related changes and the effect of venous interventions to reverse them, and to assess appropriateness of spaceflight V-US with terrestrial standards. An appropriateness tool was developed following expert panel discussions and review of terrestrial diagnostic studies, including criteria relevant to crew experience, in-flight equipment, assessment sites, ultrasound modalities, and DVT diagnosis. Microgravity-related findings reported as an increase in internal jugular vein (IJV) cross-sectional area and pressure were associated with reduced, stagnant, and retrograde flow. Changes were on average responsive to venous interventions using lower body negative pressure, Bracelets, Valsalva and Mueller manoeuvres, and contralateral IJV compression. In comparison with terrestrial standards, spaceflight V-US did not meet all appropriateness criteria. In DVT studies (n = 3), a single thrombosis was reported and only ultrasound modality criterion met the standards. In the other studies (n = 15), all the criteria were appropriate except crew experience criterion, which was appropriate in only four studies. Future practice and research should account for microgravity-related changes, evaluate individual effect of venous interventions, and adopt Earth-based V-US standards.