884 research outputs found
Renal function alterations during skeletal muscle disuse in simulated microgravity
This project was to examine the alterations in renal functions during skeletal muscle disuse in simulated microgravity. Although this area could cover a wide range of investigative efforts, the limited funding resulted in the selection of two projects. These projects would result in data contributing to an area of research deemed high priority by NASA and would address issues of the alterations in renal response to vasoactive stimuli during conditions of skeletal muscle disuse as well as investigate the contribution of skeletal muscle disuse, conditions normally found in long term human exposure to microgravity, to the balance of fluid and macromolecules within the vasculature versus the interstitium. These two projects selected are as follows: investigate the role of angiotensin 2 on renal function during periods of simulated microgravity and skeletal muscle disuse to determine if the renal response is altered to changes in circulating concentrations of angiotensin 2 compared to appropriate controls; and determine if the shift of fluid balance from vasculature to the interstitium, the two components of extracellular fluid volume, that occur during prolonged exposure to microgravity and skeletal muscle disuse is a result, in part, to alterations in the fluid and macromolecular balance in the peripheral capillary beds, of which the skeletal muscle contains the majority of recruitment capillaries. A recruitment capillary bed would be most sensitive to alterations in Starling forces and fluid and macromolecular permeability
Fluid compartment and renal function alterations in the rat during 7 and 14 day head down tilt
Exposure to conditions of microgravity for any extended duration can modify the distribution of fluid within the vascular and interstitial spaces, and eventually intracellular volume. Whether the redistribution of fluid and resetting of volume homeostasis mechanisms is appropriate for the long term environmental requirements of the body in microgravity remains to be fully defined. The event that initiates the change in fluid volume homeostasis is the cephalad movement of fluid which potentially triggers volume sensors and stretch receptors (atrial stretch with the resulting release of atrial natriuretic peptide) and suppresses adrenergic activity via the carotid and aortic arch baroreceptors. All these events act in concert to reset blood and interstitial volume to new levels, which in turn modify the renin-angiotensin system. All these factors have an influence on the kidney, the end organ for fluid volume control. How the fluid compartment volume changes interrelate with alterations in renal functions under conditions of simulated microgravity is the focus of the present investigation which utilizes 25-30 deg head-down tilt in the rat
[Volume Homeostasis and Renal Function in Rats Exposed to Simulated and Actual Microgravity]
This project has investigated mechanisms that influence alterations in compartmental fluid and electrolyte balance in microgravity and evaluates countermeasures to control renal fluid and electrolyte losses. Determining the alterations due to space flight in fluid compartments and renal function is an important component in understanding long term adaptation to spaceflight and the contribution to post-flight orthostatic intolerance. Four definition phase studies and two studies examining neuro-humoral and vascular mechanisms have been completed
Disassociation between glomerular hyperfiltration and extracellular volume in diabetic rats
Disassociation between glomerular hyperfiltration and extracellular volume in diabetic rats. The relationship of the development of glomerular hyperfiltration in diabetes to changes in extracellular fluid volume has not been previously examined. To accomplish this task, male Wistar rats were chronically cannulated in the bladder, femoral artery and vein. Control measurements of glomerular filtration rate (GFR), renal plasma flow (RPF), extracellular fluid volume (ECF), and urinary sodium excretion were performed on two separate days prior to infusion of streptozotocin (65 mg/kg body wt i.v.). After infusion of streptozotocin, the IDDM rats were separated into two groups: untreated IDDM group of rats and IDDM rats treated with insulin at doses sufficient to normalize blood glucose (Ultralente, 2 to 8 IU/day). A third group of normal non-diabetic rats served as time controls. Measurements of renal function occurred at 1, 4, 7, 11, and 15 days after infusion of streptozotocin. Blood glucose in the non-diabetic measurement period averaged 137 ± 30 mg/dl and increased from 412 ± 55 after 24 hours in the untreated diabetic rats to 533 ± 33 mg/dl after 15 days of IDDM. The time controls and the insulin-treated diabetic rats did not differ in blood glucose values at the time measurements were performed. Glomerular filtration rate increased from 1.0 ± 0.1 to 1.7 ± 0.1 ml/min/100g body wt by day 15 in the untreated diabetic rats with significant increases in GFR within 24 hours. GFR of both time controls and the insulin-treated IDDM rats did not significantly vary during the time of the study. The increase in GFR in the untreated IDDM group was associated with a concomitant increase in RPF. However, ECF decreased in both the insulin treated and untreated groups by one day after streptozotocin infusion and was less than control throughout the 15 day IDDM measurement period. Therefore, the data indicate that the development of hyperfiltration in IDDM is not caused by ECF expansion and cannot be temporally linked to changes in ECF
Review of Intra-Articular Use of Antibiotics and Antiseptic Irrigation and Their Systematic Association with Chondrolysis
Introduction. Intra-articular antibiotics have been proposed as a treatment for septic arthritis to allow for high local concentrations without subjecting a patient to the toxicity/side effects of systemic therapy. However, there is concern for chondrotoxicity with intra-articular use of these solutions in high concentrations. The purpose of this systematic review was to evaluate the intra-articular use of antibiotics and antiseptic solutions, and to determine their association with chondrolysis following in vitro or in vivo administration.
Methods. A systematic review was conducted following PRISMA guidelines through PubMed, Clinical Key, OVID, and Google Scholar. Studies in English were included if they evaluated for chondrotoxicity following antibiotic exposure.
Results. The initial search resulted in 228 studies, with 36 meeting criteria. Overall, 7 of the 24 (29%) agents were non-chondrotoxic: minocycline, tetracycline, chloramphenicol, teicoplanin, pefloxacin, linezolid, polymyxin-bacitracin. Eight (33%) agents had inconsistent results: doxycycline, ceftriaxone, gentamicin, vancomycin, ciprofloxacin, ofloxacin, chlorhexidine, and povidone iodine. Chondrotoxicity was evident with 9 (38%) agents, all of which were also dose-dependently chondrotoxic based on reported estimated half maximal inhibitory concentrations (est.IC50): amikacin (est. IC50 = 0.31-2.74 mg/mL), neomycin (0.82), cefazolin (1.67-3.95), ceftazidime (3.16-3.59), ampicillin-sulbactam (8.64 - >25), penicillin (11.61), amoxicillin (14.01), imipenem (>25), and tobramycin (>25). Additionally, chondroprotective effects of doxycycline and minocycline were reported.
Conclusions. This systematic review identified agents that may be used in the treatment of septic arthritis. Nine agents should be avoided due to their dose-dependent chondrotoxic effects. Further studies are needed to clarify the safety of these medications for human intra-articular use
A Titanium Nitride Absorber for Controlling Optical Crosstalk in Horn-Coupled Aluminum LEKID Arrays for Millimeter Wavelengths
We discuss the design and measured performance of a titanium nitride (TiN)
mesh absorber we are developing for controlling optical crosstalk in
horn-coupled lumped-element kinetic inductance detector arrays for
millimeter-wavelengths. This absorber was added to the fused silica
anti-reflection coating attached to previously-characterized, 20-element
prototype arrays of LEKIDs fabricated from thin-film aluminum on silicon
substrates. To test the TiN crosstalk absorber, we compared the measured
response and noise properties of LEKID arrays with and without the TiN mesh.
For this test, the LEKIDs were illuminated with an adjustable, incoherent
electronic millimeter-wave source. Our measurements show that the optical
crosstalk in the LEKID array with the TiN absorber is reduced by 66\% on
average, so the approach is effective and a viable candidate for future
kilo-pixel arrays.Comment: 7 pages, 5 figures, accepted for publication in the Journal of Low
Temperature Physic
Earth Observations and Integrative Models in Support of Food and Water Security
Global food production depends upon many factors that Earth observing satellites routinely measure about water, energy, weather, and ecosystems. Increasingly sophisticated, publicly-available satellite data products can improve efficiencies in resource management and provide earlier indication of environmental disruption. Satellite remote sensing provides a consistent, long-term record that can be used effectively to detect large-scale features over time, such as a developing drought. Accuracy and capabilities have increased along with the range of Earth observations and derived products that can support food security decisions with actionable information. This paper highlights major capabilities facilitated by satellite observations and physical models that have been developed and validated using remotely-sensed observations. Although we primarily focus on variables relevant to agriculture, we also include a brief description of the growing use of Earth observations in support of aquaculture and fisheries
SPIDER: a balloon-borne CMB polarimeter for large angular scales
We describe SPIDER, a balloon-borne instrument to map the polarization of the
millimeter-wave sky with degree angular resolution. Spider consists of six
monochromatic refracting telescopes, each illuminating a focal plane of
large-format antenna-coupled bolometer arrays. A total of 2,624 superconducting
transition-edge sensors are distributed among three observing bands centered at
90, 150, and 280 GHz. A cold half-wave plate at the aperture of each telescope
modulates the polarization of incoming light to control systematics. Spider's
first flight will be a 20-30-day Antarctic balloon campaign in December 2011.
This flight will map \sim8% of the sky to achieve unprecedented sensitivity to
the polarization signature of the gravitational wave background predicted by
inflationary cosmology. The Spider mission will also serve as a proving ground
for these detector technologies in preparation for a future satellite mission.Comment: 12 pages, 6 figures; as published in the conference proceedings for
SPIE Millimeter, Submillimeter, and Far-Infrared Detectors and
Instrumentation for Astronomy V (2010
Design and construction of a carbon fiber gondola for the SPIDER balloon-borne telescope
We introduce the light-weight carbon fiber and aluminum gondola designed for
the SPIDER balloon-borne telescope. SPIDER is designed to measure the
polarization of the Cosmic Microwave Background radiation with unprecedented
sensitivity and control of systematics in search of the imprint of inflation: a
period of exponential expansion in the early Universe. The requirements of this
balloon-borne instrument put tight constrains on the mass budget of the
payload. The SPIDER gondola is designed to house the experiment and guarantee
its operational and structural integrity during its balloon-borne flight, while
using less than 10% of the total mass of the payload. We present a construction
method for the gondola based on carbon fiber reinforced polymer tubes with
aluminum inserts and aluminum multi-tube joints. We describe the validation of
the model through Finite Element Analysis and mechanical tests.Comment: 16 pages, 11 figures. Presented at SPIE Ground-based and Airborne
Telescopes V, June 23, 2014. To be published in Proceedings of SPIE Volume
914
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