Publications by authors named "Whitson P"

Low Earth Orbit (LEO) has emerged as a unique environment for evaluating altered stem cell properties in microgravity. LEO has become increasingly accessible for research and development due to progress in private spaceflight. Axiom Mission 2 (Ax-2) was launched as the second all-private astronaut mission to the International Space Station (ISS).

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Background: Existing research regarding design improvements to the operating room (OR) is scarce and emphasizes the compelling need to measure and test new design strategies and interventions.

Methods: We propose a conceptual framework for measuring and improving OR physical space design by outlining how two existing measurement schemes can be adapted for ORs. The structure, process, outcomes model described by Donabedian in 1966 is used to show how each of these three measurement approaches can be used to evaluate OR design.

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Polarizable colloids are expected to form crystalline equilibrium phases when exposed to a steady, uniform field. However, when colloids become localized this field-induced phase transition arrests and the suspension persists indefinitely as a kinetically trapped, percolated structure. We anneal such gels formed from magneto-rheological fluids by toggling the field strength at varied frequencies.

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Background: The transition to microgravity eliminates the hydrostatic gradients in the vascular system. The resulting fluid redistribution commonly manifests as facial edema, engorgement of the external neck veins, nasal congestion, and headache. This experiment examined the responses to modified Valsalva and Mueller maneuvers measured by cardiac and vascular ultrasound (ECHO) in a baseline steady state and under the influence of thigh occlusion cuffs available as a countermeasure device (Braslet cuffs).

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Purpose: Exposure to microgravity affects human physiology and results in changes in urinary chemical composition during and after spaceflight, favoring an increased risk of renal stones. We assessed the efficacy of potassium citrate to decrease the stone risk during and after spaceflight.

Materials And Methods: The study was done in 30 long duration spaceflight crew members to the space stations Mir and International Space Station.

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Article Synopsis
  • An operational diagnostic imaging capability in spaceflight improves medical support by allowing for better diagnosis and treatment of health issues, thus reducing mission impacts and the need for crew evacuation.
  • The study highlights the first genitourinary ultrasound performed in space, evaluating quality and remote guidance techniques while demonstrating that a nonphysician astronaut can conduct effective examinations with support from Earth-based sonographers.
  • This process confirmed that even minimally trained crew members can perform valuable ultrasound diagnostics in microgravity, leading to better medical care during space missions.
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Introduction: With the continued construction of the International Space Station, humans are living longer in the microgravity environment of space. However, many questions still exist as to the physiological effects of spaceflight on the human body. Bone loss, cardiovascular changes, and muscle atrophy are well-documented health risks to humans during spaceflight.

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Background: Focused assessment with sonography for trauma (FAST) examination has been proved accurate for diagnosing trauma when performed by nonradiologist physicians. Recent reports have suggested that nonphysicians also may be able to perform the FAST examination reliably. A multipurpose ultrasound system is installed on the International Space Station as a component of the Human Research Facility.

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Rat osteoblasts were cultured aboard a space shuttle for 4 and 5 days. Cells were treated with 1 nM 1alpha,25-dihydroxyvitamin D(3) (VD) for the last 1 day. The conditioned media were harvested.

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Head-down bed rest changes the values of many cardiovascular and endocrine variables and also elicits significant hypovolemia. Because previous studies had not controlled for hypovolemia, it is unknown whether the reported changes were primary effects of bed rest or secondary effects of bed rest-induced hypovolemia. We hypothesized that restoring plasma volume with salt tablets and water after 12 days of head-down bed rest would result in an absence of hemodynamic and endocrine changes and a reduced incidence of orthostatic hypotension.

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Rat osteoblasts were cultured aboard a space shuttle for 4 or 5 days. Cells were exposed to 1alpha, 25 dihydroxyvitamin D(3) during the last 20 h and then solubilized by guanidine solution. The mRNA levels for molecular chaperones were analyzed by semi-quantitative RT-PCR.

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Background: A negative fluid balance during bed rest (BR) is accompanied by decreased plasma volume (PV) which contributes to cardiovascular deconditioning.

Hypothesis: We hypothesized that increasing dietary sodium while controlling fluid intake would increase plasma osmolality (POSM), stimulate fluid conserving hormones, and reduce fluid/electrolyte (F/E) losses during BR; conversely, decreasing dietary sodium would decrease POSM, suppress fluid conserving hormones, and increase F/E losses.

Methods: We controlled fluid intake (30 ml x kg(-1) x d(-1)) in 17 men who consumed either a 4.

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Host selection can be a strategy to simplify downstream processing for protein recovery. Advancing capabilities for using plants as hosts offers new host opportunities that have received only limited attention from a downstream processing perspective. Here, we investigated the potential of using a polycationic precipitating agent (polyethylenimine; PEI) to precipitate an acidic model protein (beta-glucuronidase; GUS) from aqueous plant extracts.

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This minireview provides an overview of known and potential gender differences in physiological responses to spaceflight. The paper covers cardiovascular and exercise physiology, barophysiology and decompression sickness, renal stone risk, immunology, neurovestibular and sensorimotor function, nutrition, pharmacotherapeutics, and reproduction. Potential health and functional impacts associated with the various physiological changes during spaceflight are discussed, and areas needing additional research are highlighted.

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Background: The formation of a renal stone during space flight may have serious negative effects on the health of the crewmember and the success of the mission. Urinary biochemical factors and the influence of dietary factors associated with renal stone development were assessed during long duration Mir Space Station missions.

Methods: Twenty-four-hour urine samples were collected prior to, during and following long duration space flight.

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Exposure to the microgravity environment results in many metabolic and physiological changes to humans. Body fluid volumes, electrolyte levels, and bone and muscle undergo changes as the human body adapts to the weightless environment. This investigation examined the role of these physiologic changes to the potentially serious consequences of renal stone formation.

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Background: Urine composition in astronauts during and immediately after spaceflight changes in ways that increase the renal stone-forming potential for calcium oxalate, calcium phosphate, and uric acid saturation. We examined the effect of urine volume on the risk of renal stone formation in 356 astronauts.

Methods: Renal stone-forming risk was evaluated from 24-h urine samples collected from astronauts before and after 4- to 17-d Space Shuttle flights.

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The secretion of prostacyclin (PGI2) by endothelial cells is regulated by shear stress. Prostaglandin H synthase (PGHS) is considered to be a key limiting enzyme in the synthesis of PGI2 from arachidonic acid. Endothelial cells were cultured in the presence of 4, 15, or 25 dyn/cm2 shear stress using a parallel plate flow chamber to assess the effect of shear stress on both PGHS isoforms, PGHS-1 and PGHS-2.

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Increased risk of renal stone formation during space flight has been linked primarily to increased calcium excretion from bone demineralization induced by space flight. Other factors contributing to increased risk include increased urinary calcium oxalate supersaturation, while urinary citrate, magnesium and volume are all decreased. The aim of this study was to increase the predictive value of stone risk profiles for crew members during space flight by evaluating the excretion of urinary protein inhibitors of calcium crystallization so that more comprehensive stone risk profiles could relate mineral saturation to the concentrations of inhibitor proteins.

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Background/aims: Astronauts exposed to microgravity during the course of spaceflight undergo physiologic changes that alter the urinary environment so as to increase the risk of renal stone formation. This study was undertaken to identify a simple method with which to evaluate the potential risk of renal stone development during spaceflight.

Method: We used a large database of urinary risk factors obtained from 323 astronauts before and after spaceflight to generate a mathematical model with which to predict the urinary supersaturation of calcium stone forming salts.

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Rat osteoblasts were cultured for 4 or 5 days during a Space Shuttle mission. After 20-h treatment with 1alpha,25-dihydroxyvitamin D3, conditioned media were harvested and cellular DNA and/or RNA were fixed on board. The insulin-like growth factor binding protein (IGF BP)-3 levels in the media were three- and tenfold higher than in ground controls on the fourth and fifth flight days, as quantitated by Western ligand blotting and radioimmunoassay, respectively.

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Purpose: The metabolic and environmental factors influencing renal stone formation before, during, and after Space Shuttle flights were assessed. We established the contributing roles of dietary factors in relationship to the urinary risk factors associated with renal stone formation.

Materials And Methods: 24-hr.

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