Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “CREATININE”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

49 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Survival after aortic valve replacement for severe aortic stenosis with low transvalvular gradients and severe left ventricular dysfunction

OBJECTIVE: We sought to assess whether aortic valve replacement (AVR) among patients with severe aortic stenosis (AS), severe left ventricular (LV) dysfunction and a low transvalvular gradient (TVG) is associated with improved survival. BACKGROUND: The optimal management of patients with severe AS with severe LV dysfunction and a low TVG remains controversial. METHODS: Between 1990 and 1998, we evaluated 68 patients who underwent AVR at our institution (AVR group) and 89 patients who did not undergo AVR (control group), with an aortic valve area < or = 0.75 cm(2), LV ejection fraction < or = 35% and mean gradient < or = 30 mm Hg. Using propensity analysis, survival was compared between a cohort of 39 patients in the AVR group and 56 patients in the control group. RESULTS: Despite well-matched baseline characteristics among propensity-matched patients, the one- and four-year survival rates were markedly improved in patients in the AVR group (82% and 78%), as compared with patients in the control group (41% and 15%; p < 0.0001). By multivariable analysis, the main predictor of improved survival was AVR (adjusted risk ratio 0.19, 95% confidence interval 0.09 to 0.39; p < 0.0001). The only other predictors of mortality were age and the serum creatinine level. CONCLUSIONS: Among select patients with severe AS, severe LV dysfunction and a low TVG, AVR was associated with significantly improved survival.

NASA Discipline Cardiopulmonary↗
NASA NTRS1977

Space motion sickness medications: interference with biomedical parameters

The possibility that drugs administered to Skylab 3 (SL-3) and 4 (SL-4) crewmen for space motion sickness may have interfered with their biomedical evaluation in space was investigated. Healthy volunteers received combinations of Scopolamine/Dexedrine for four days in regimens similar to those used in these missions. Urine samples, heart rate, body temperature, mood and performance were analyzed for drug-related changes. Twenty-four hour urine samples were analyzed by the same procedures as those used to analyze the flight samples. Hormone concentrations determined included cortisol, epinephrine, norepinephrine, aldosterone and antidiuretic hormone (ADH). In addition, volume, specific gravity, osmolarity, sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), chloride (Cl), inorganic phosphate, uric acid and creatinine were measured. Performance was not affected by the Scopolamine/Dexedrine. The drug combination increased daily mean heart rate (HR) significantly in all the subjects and daily mean rectal temperature (RT) in some of the subjects. A 2-4 hr phase shift in the HR circadian rhythm was also observed which indicates that internal circadian synchrony was disturbed by the drugs. Psychological and subjective evaluation indicated that the subjects could usually identify which days they were given the drugs by an increase in tension and anxiety, decreased patience, restlessness, decreased appetite, difficulty in sleeping and feelings of increased heart rate and body temperature. Urinary electrolytes were not changed significantly by the drug, but marked and significant changes occurred in urine volume and hormone excretion patterns. Scopolamine/Dexedrine caused consistent elevations in urinary cortisol and epinephrine and a transient elevation in ADH. Norepinephrine excretion was decreased, but there was no significant change in aldosterone excretion or in 24 hr urine volume. A comparison of these findings with the first four days of inflight data from the SL-3 and SL-4 missions leads to the conclusion that the dramatic increases in aldosterone excretion during the first three days of spaceflight probably can be directly attributed to weightlessness, whereas the antimotion sickness medication could have substantially contributed to the early increased excretion of epinephrine and cortisol during these missions.

manned↗
NASA NTRS2001

Evidence for central venous pressure resetting during initial exposure to microgravity

We measured central venous pressure (CVP); plasma volume (PV); urine volume rate (UVR); renal excretion of sodium (UNa); and renal clearances of creatinine, sodium, and osmolality before and after acute volume infusion to test the hypothesis that exposure to microgravity causes resetting of the CVP operating point. Six rhesus monkeys underwent two experimental conditions in a crossover counterbalance design: 1) continuous exposure to 10 degrees head-down tilt (HDT) and 2) a control, defined as 16 h/day of 80 degrees head-up tilt and 8 h prone. After 48 h of exposure to either test condition, a 120-min course of continuous infusion of isotonic saline (0.4 ml. kg(-1). min(-1) iv) was administered. Baseline CVP was lower (P = 0.011) in HDT (2.3 +/- 0.3 mmHg) compared with the control (4.5 +/- 1.4 mmHg) condition. After 2 h of saline infusion, CVP was elevated (P = 0.002) to a similar magnitude (P = 0.485) in HDT (DeltaCVP = 2.7 +/- 0.8 mmHg) and control (DeltaCVP = 2.3 +/- 0.8 mmHg) conditions and returned to preinfusion levels 18 h postinfusion in both treatments. PV followed the same pattern as CVP. The response relationships between CVP and UVR and between CVP and UNa shifted to the left with HDT. The restoration of CVP and PV to lower preinfusion levels after volume loading in HDT compared with control supports the notion that lower CVP during HDT may reflect a new operating point about which vascular volume is regulated. These results may explain the ineffective fluid intake procedures currently employed to treat patients and astronauts.

NASA Discipline Cardiopulmonary↗
NASA NTRS1987

The preservation of urine samples for determination of renal stone risk factors

A preservation technique for urine specimens before determination of stone risk factors was evaluated. The purpose of these experiments was to prove the effectiveness of the preservatives used to prevent changes in the concentrations of those constituents measured. Measured concentrations in fresh specimens were compared with those in the same specimens after storage with the preservatives. Refrigeration at 4 degrees C up to five days was appropriate in a laboratory setting, as no significant changes in urinary concentrations occurred. Refrigeration, however, did not offer a convenient method for shipping. Chemical preservation was found to be an effective alternative to refrigeration. Thymol prevented changes in concentration of pH, citrate, uric acid, sulfate, sodium, potassium, and cyclic AMP, while a mixture of hydrochloric (HCl) acid and boric acid prevented changes in calcium, magnesium, phosphorus, oxalate, ammonium, and creatinine. Thus, the addition of thymol or HCl/boric acid to urine specimens will prevent significant changes in the concentrations of stone risk factors.

Non-NASA Center↗
NASA NTRS2001

Influence of head-down bed rest on the circadian rhythms of hormones and electrolytes involved in hydroelectrolytic regulation

We investigated in six men the impact of a 17-day head-down bed rest (HDBR) on the circadian rhythms of the hormones and electrolytes involved in hydroelectrolytic regulation. This HDBR study was designed to mimic an actual spaceflight. Urine samples were collected at each voiding before, during and after HDBR. Urinary excretion of aldosterone, arginine vasopressin (AVP), cyclic guanosine monophosphate (cGMP), cortisol, electrolytes (Na+ and K+) and creatinine were determined. HDBR resulted in a significant reduction of body mass (P < 0.01) and of caloric intake [mean (SEM) 2,778 (37) kcal.24 h(-1) to 2,450 (36) kcal.24 h(-1), where 1 kcal.h(-1) = 1.163 J.s(-1); P< 0.01]. There was a significant increase in diastolic blood pressure [71.8 (0.7) mmHg vs 75.6 (0.91) mmHg], with no significant changes in either systolic blood pressure or heart rate. The nocturnal hormonal decrease of aldosterone was clearly evident only before and after HDBR, but the day/night difference did not appear during HDBR. The rhythm of K+ excretion was unchanged during HDBR, whereas for Na+ excretion, a large decrease was shown during the night as compared to the day. The circadian rhythm of cortisol persisted. These data suggest that exposure to a 17-day HDBR could induce an exaggeration of the amplitude of the Na+ rhythm and abolition of the aldosterone rhythm.

NASA Center ARC↗
NASA NTRS1999

Contrasting effects of vasodilators on blood pressure and sodium balance in the hypertension of autonomic failure

Supine hypertension, which is very common in patients with autonomic failure, limits the use of pressor agents and induces nighttime natriuresis. In 13 patients with severe orthostatic hypotension due to autonomic failure (7 women, 6 men, 72 +/- 3 yr) and supine hypertension, the effect of 30 mg nifedipine (n = 10) and 0.025 to 0.2 mg/h nitroglycerin patch (n = 11) on supine BP, renal sodium handling, and orthostatic tolerance was determined. Medications were given at 8 p.m.; patients stood up at 8 a.m. Nitroglycerin was removed at 6 a.m. Compared with placebo, nifedipine and nitroglycerin decreased systolic BP during the night by a maximum of 37 +/- 9 and 36 +/- 10 mmHg, respectively (P < 0.01). At 8 a.m., supine systolic BP was 23 +/- 7 mmHg lower with nifedipine than with placebo (P < 0.05), but was similar with nitroglycerin and placebo. Sodium excretion during the night was not reduced with nitroglycerin (0.13 +/- 0.02 mmol/mg creatinine [Cr] versus 0.15 +/- 0.03 mmol/mg Cr with placebo), but it was increased with nifedipine (0.35 +/- 0.06 mmol/mg Cr versus 0.13 +/- 0.02 mmol/mg Cr with placebo, P < 0.05). Nifedipine but not nitroglycerin worsened orthostatic hypotension in the morning. It is concluded that nifedipine and transdermal nitroglycerin are effective in controlling supine hypertension in patients with autonomic failure. However, nifedipine has a prolonged depressor effect and worsens orthostatic hypotension in the morning. The decrease in pressure natriuresis that would be expected with the substantial decrease in BP obtained with nitroglycerin and nifedipine may be offset by a direct effect of both drugs on renal sodium handling.

Clinical Trial↗
NASA NTRS1997

Quantification of urinary uric acid in the presence of thymol and thimerosal by high-performance liquid chromatography

A high-performance liquid chromatographic method was developed as an alternative to automated enzymatic analysis of uric acid in human urine preserved with thymol and/or thimerosal. Uric acid (tR = 10 min) and creatinine (tR = 5 min) were separated and quantified during isocratic elution (0.025 M acetate buffer, pH 4.5) from a mu Bondapak C18 column. The uric-acid peak was identified chemically by incubating urine samples with uricase. The thymol/thimerosal peak appeared at 31 min during the washing step and did not interfere with the analysis. We validated the high-performance liquid chromatographic method for linearity, precision and accuracy, and the results were found to be excellent.

NASA Discipline Regulatory Physiology↗
NASA NTRS1996

Noninvasive markers of bone metabolism in the rhesus monkey: normal effects of age and gender

Measurement of bone turnover in conditions such as osteoporosis has been limited by the need for invasive iliac bone biopsy to reliably determine parameters of bone metabolism. Recent advances in the area of serum and urinary markers of bone metabolism have raised the possibility for noninvasive measurements; however, little nonhuman primate data exist for these parameters. The purpose of this experiment was to define the normal range and variability of several of the newer noninvasive bone markers which are currently under investigation in humans. The primary intent was to determine age and gender variability, as well as provide some normative data for future experiments in nonhuman primates. Twenty-four rhesus macaques were divided into equal groups of male and female according to the following age groupings: 3 years, 5-10 years, 15-20 years, and > 25 years. Urine was collected three times daily for a four-day period and measured for several markers of bone turnoverm including pyridinoline (PYD), deoxypyrodinoline (DPD), hydroxyproline, and creatinine. Bone mineral density measurements of the lumbar spine were performed at the beginning and end of the study period. Serum was also obtained at the time of bone densitometry for measurement of osteocalcin levels by radioimmunoassay. There were no significant differences in bone mineral density, urine PYD, or urine DPD based on gender. Bone density was lowest in the youngest animals, peaked in the 15-20-year group, but again decreased in the oldest animals. The osteocalcin, PYD, and DPD levels followed an inversely related pattern to bone density. The most important result was the relative age insensitivity of the ratio of PYD:DPD in monkeys up to age 20 years. Since bone density changes take months or years to become measurable and iliac biopsies are invasive, the PYD/DPD marker ratio may have important implications for rapid noninvasive measurement of the effects of potential treatments for osteoporosis in the non-human primate model.

NASA Discipline Musculoskeletal↗
NASA NTRS1993

Changes in markers of bone formation and resorption in a bed rest model of weightlessness

To study the mechanism of bone loss in physical unloading, we examined indices of bone formation and bone resorption in the serum and urine of eight healthy men during a 7 day -6 degrees head-down tilt bed rest. Prompt increases in markers of resorption--pyridinoline (PD), deoxypyridinoline (DPD), and hydroxyproline (Hyp)/g creatinine--during the first few days of inactivity were paralleled by tartrate-resistant acid phosphatase (TRAP) with significant increases in all these markers by day 4 of bed rest. An index of formation, skeletal alkaline phosphatase (SALP), did not change during bed rest and showed a moderate 15% increase 1 week after reambulation. In contrast to SALP, serum osteocalcin (OC) began increasing the day preceding the increase in Hyp, remained elevated for the duration of the bed rest, and returned to pre-bed rest values within 5 days of reambulation. Similarly, DPD increased significantly at the onset of bed rest, remained elevated for the duration of bed rest, and returned to pre-bed rest levels upon reambulation. On the other hand, the other three indices of resorption, Hyp, PD, and TRAP, remained elevated for 2 weeks after reambulation. The most sensitive indices of the levels of physical activity proved to be the noncollagenous protein, OC, and the collagen crosslinker, DPD. The bed rest values of both these markers were significantly elevated compared to both the pre-bed rest values and the post-bed rest values. The sequence of changes in the circulating markers of bone metabolism indicated that increases in serum OC are the earliest responses of bone to head-down tilt bed rest.

NASA Discipline Number 26-10↗
NASA NTRS1993

Renal and cardiovascular responses to water immersion in trained runners and swimmers

The purpose of this study was to determine if fluid-electrolyte, renal, hormonal, and cardiovascular responses during and after multi-hour water immersion were associated with aerobic training. Additionally, we compared these responses in those who trained in a hypogravic versus a 1-g environment. Seventeen men comprised three similarly aged groups: six long-distance runners, five competitive swimmers, and six untrained control subjects. Each subject underwent 5 h of immersion in water [mean (SE)] 36.0 (0.5) degrees C to the neck. Immediately before and at each hour of immersion, blood and urine samples were collected and analyzed for sodium (Na), potassium, osmolality, and creatinine (Cr). Plasma antidiuretic hormone and aldosterone were also measured. Hematocrits were used to calculate relative changes in plasma volume (% delta Vpl). Heart rate response to submaximal cycle ergometer exercise (35% peak oxygen uptake) was measured before and after water immersion. Water immersion induced significant increases in urine flow, Na clearance (CNa), and a 3-5% decrease in Vpl. Urine flow during immersion was greater (P < 0.05) in runners [2.4 (0.4) ml.min-1] compared to controls [1.3 (0.1) ml.min-1]. However, % delta Vpl, CCr, CNa and CH2O during immersion were not different (P > 0.05) between runners, swimmers, and controls. After 5 h of immersion, there was an increase (P < 0.05) in submaximal exercise heart rate of 9 (3) and 10 (3) beats.min-1 in both runners and controls, respectively, but no change (P > 0.05) was observed in swimmers.(ABSTRACT TRUNCATED AT 250 WORDS).

Running/physiology↗
NASA NTRS2006

Nutritional Status in Humans during Long-Duration Bed Rest

Bed rest is a valuable ground-based model for many of the physiological changes associated with space flight. A series of studies was undertaken to evaluate nutritional changes during and after 60 or 90 days of -6 head-down-tilt bed rest. A total of 11 subjects (8 M, 3 F; age 26-55 y) participated in the studies. Blood and urine were collected twice before bed rest and once per month during bed rest. Samples were analyzed in batch at the end of each study. Data were analyzed using repeated-measures ANOVA. Markers of bone resorption (such as n-telopeptide excretion, p less than 0.05) increased during bed rest, and 25-OH vitamin D status tended to decline (p=0.06). During bed rest oxidative damage markers, such as superoxide dismutase increased (p less than 0.01) and 8-(OH)-2'-deoxyguanosine tended to increase (p=0.07); whereas total antioxidant capacity decreased (p less than 0.02). Iron status indices showed patterns of increased iron stores, with decreased transferrin receptors (p less than 0.001). Biochemical markers revealed a tendency toward a loss of muscle mass, by lower excretion of creatinine and 3-methyl-histidine during bed rest. All of these changes are very similar to those observed during space flight, and further document the utility of bed rest as a model of space flight.

Smith, Scott M.↗
NASA NTRS2003

The Use of Chlorhexidine/n-Propyl Gallate (CPG) as an Ambient-Temperature Urine Preservative

A safe, effective ambient temperature urine preservative, chlorhexidine/n-propyl gallate (CPG), has been formulated for use during spacefli ght that reduces the effects of oxidation and bacterial contamination on sample integrity while maintaining urine pH. The ability of this preservative to maintain stability of nine key analytes was evaluated for a period of one year. CPG effectively maintained stability of a mmonia, total nitrogen, 3-methylhistidine, chloride, sodium, potassiu m, and urea; however, creatinine and osmolality were not preserved by CPG. These data indicate that CPG offers prolonged room-temperature storage for multiple urine analytes, reducing the requirements for f rozen urine storage on future spaceflights. Iii medical applications on Earth, this technology can allow urine samples to be collected in remote settings and eliminate the need to ship frozen samples.

Nillen, Jeannie L.↗
NASA NTRS2013

NASA Tech Briefs, September 2013

Topics include: ISS Ammonia Leak Detection Through X-Ray Fluorescence; A System for Measuring the Sway of the Vehicle Assembly Building; Fast, High-Precision Readout Circuit for Detector Arrays; Victim Simulator for Victim Detection Radar; Hydrometeor Size Distribution Measurements by Imaging the Attenuation of a Laser Spot; Quasi-Linear Circuit; High-Speed, High-Resolution Time-to-Digital Conversion; Li-Ion Battery and Supercapacitor Hybrid Design for Long Extravehicular Activities; Ultrasonic Low-Friction Containment Plate for Thermal and Ultrasonic Stir Weld Processes; High-Powered, Ultrasonically Assisted Thermal Stir Welding; Next-Generation MKIII Lightweight HUT/Hatch Assembly; Centrifugal Sieve for Gravity-Level-Independent Size; Segregation of Granular Materials; Ion Exchange Technology Development in Support of the Urine Processor Assembly; Nickel-Graphite Composite Compliant Interface and/or Hot Shoe Material; UltraSail CubeSat Solar Sail Flight Experiment; Mechanism for Deploying a Long, Thin-Film Antenna From a Rover; Counterflow Regolith Heat Exchanger; Acquisition and Retaining Granular Samples via a Rotating Coring Bit; Very-Low-Cost, Rugged Vacuum System; Medicine Delivery Device With Integrated Sterilization and Detection; FRET-Aptamer Assays for Bone Marker Assessment, C-Telopeptide, Creatinine, and Vitamin D; Multimode Directional Coupler for Utilization of Harmonic Frequencies from TWTAs; Dual-Polarization, Multi-Frequency Antenna Array for use with Hurricane Imaging Radiometer; Complementary Barrier Infrared Detector (CBIRD) Contact Methods; Autonomous Control of Space Nuclear Reactors; High-Power, High-Speed Electro-Optic Pockels Cell Modulator; Covariance Analysis Tool (G-CAT) for Computing Ascent, Descent, and Landing Errors; Enigma Version 12; Micrometeoroid and Orbital Debris (MMOD) Shield Ballistic Limit Analysis Program; Spitzer Telemetry Processing System; Planetary Protection Bioburden Analysis Program; Wing Leading Edge RCC Rapid Response Damage Prediction Tool (IMPACT2); ISSM: Ice Sheet System Model; Automated Loads Analysis System (ATLAS); Integrated Main Propulsion System Performance Reconstruction Process/Models. Phoenix Telemetry Processor; Contact Graph Routing Enhancements Developed in ION for DTN; GFEChutes Lo-Fi; Advanced Strategic and Tactical Relay Request Management for the Mars Relay Operations Service; Software for Generating Troposphere Corrections for InSAR Using GPS and Weather Model Data; Ionospheric Specifications for SAR Interferometry (ISSI); Implementation of a Wavefront-Sensing Algorithm; Sally Ride EarthKAM - Automated Image Geo-Referencing Using Google Earth Web Plug-In; Trade Space Specification Tool (TSST) for Rapid Mission Architecture (Version 1.2); Acoustic Emission Analysis Applet (AEAA) Software; Memory-Efficient Onboard Rock Segmentation; Advanced Multimission Operations System (ATMO); Robot Sequencing and Visualization Program (RSVP); Automating Hyperspectral Data for Rapid Response in Volcanic Emergencies; Raster-Based Approach to Solar Pressure Modeling; Space Images for NASA JPL Android Version; Kinect Engineering with Learning (KEWL); Spacecraft 3D Augmented Reality Mobile App; MPST Software: grl_pef_check; Real-Time Multimission Event Notification System for Mars Relay; SIM_EXPLORE: Software for Directed Exploration of Complex Systems; Mobile Timekeeping Application Built on Reverse-Engineered JPL Infrastructure; Advanced Query and Data Mining Capabilities for MaROS; Jettison Engineering Trajectory Tool; MPST Software: grl_suppdoc; PredGuid+A: Orion Entry Guidance Modified for Aerocapture; Planning Coverage Campaigns for Mission Design and Analysis: CLASP for DESDynl; and Space Place Prime.

Source record↗