1,750 research outputs found
Arthropathies Associated with Basic Calcium Phosphate Crystals
Basic calcium phosphate (BCP) crystals refer to a family of crystals including partially carbonate substituted hydroxyapatite, octacalcium phosphate, and tricalcium phosphate. These crystals have been found in and around joints and have been associated with several forms of arthritis and periarthritis. Identification of BCP crystals remains problematic because of the lack of a simple, reliable analytic procedure. Methods currently in use include alizarin red S staining, labelled diphosphonate binding, scanning and transmission electron microscopy with energy dispersive X-ray microanalysis, X-ray diffraction, and atomic force microscopy. Periarthropathies associated with BCP crystals include calcific tendinitis and bursitis. Intra-articular BCP crystal deposition is common in osteoarthritis, often found together with calcium pyrophosphate dihydrate crystals. Uncommon conditions in which BCP crystals are found include destructive shoulder arthropathies, acute inflammatory attacks of arthritis, and erosive arthritis. Secondary deposition of BCP crystals has been observed in chronic renal failure, in patients with collagen vascular diseases, following neurologic injury and after local corticosteroid injection
Variations in subcuticular acid phosphatase activity during the molting cycle of the euphausiid crustacean, Thysanoessa raschii (M. Sars) Hansen
A histochemical technique, applicable to intact euphausiids, has been used in the laboratory to demonstrate variations in the level of subcuticular acid phosphatase activity during the molting cycle of Thysanoessa raschii; it shows that there is a marked increase in such activity during the 24 hours in which ecdysis occurs. We suggest that the technique could form a useful tool in future studies on euphausiid biology since it would allow, for example, assessments of the numbers of individuals in any one collection or population that is passing through this particular 24-hour period at the time of sampling
Calcium Pyrophosphate Crystal Deposition: The Effect of Soluble Iron in a Kinetic Study Using a Gelatin Matrix Model
The kinetics of calcium pyrophosphate dihydrate (CPPD) crystal growth was studied by allowing calcium and pyrophosphate (PPi-4) ions to diffuse through a denatured collagen matrix (biological grade gelatin) in the presence of either ferric or ferrous ions. Ferric and, to some extent, ferrous ions blocked the migration of the PPi-4 diffusion gradient. This retardation in the [PPi-4] gradient led to numerous changes in the patterns of CPPD crystal formation. At the initial stages of crystal growth, the iron ions induced more crystal growth compared to control. At later incubation times, ferrous and ferric ions enhanced crystal growth at the expense of crystal nucleation. The presence of both ferrous and ferric ions resulted in the more rapid formation of the two crystals observed in vivo, triclinic CPPD and monoclinic CPPD. Further, both ferrous and ferric ions also reduced the solubility of the crystalline material in the broad diffuse band which formed when the Ca+2 and PPi-4 gradients first met. In this system, the presence of either ferrous or ferric ions increased the amount of hydroxyproline included in the crystalline precipitates. Iron was also incorporated into the crystals, particularly into the triclinic CPPD and monoclinic CPPD crystals
Calcium Pyrophosphate Crystal Deposition: The Effect of Monosodium Urate and Apatite Crystals in a Kinetic Study Using a Gelatin Matrix Model
The kinetics of calcium pyrophosphate dihydrate (CPPD) crystal growth was studied by allowing calcium and pyrophosphate (PPi-4) ions to diffuse through a denatured collagen matrix (biological grade gelatin) in the presence of either monosodium urate monohydrate (MSU) or hydroxyapatite (HA) crystals. In this in vitro model system, MSU crystals significantly altered the kinetics of PPi-4 ionic diffusion through the gelatin matrix by allowing the [PPi-4] gradient to fall off much more rapidly, suggesting an increased level of scavenging of PPi-4 ions into crystalline materials. Even more significantly, the presence of MSU crystals markedly influenced the crystal growth morphology of triclinic CPPD, producing that observed in vivo. A large number of epitaxially dimensional matches between MSU and triclinic (t) and monoclinic (m) CPPD were identified, suggesting that MSU crystals can epitaxially induce CPPD crystal growth. This finding supports the hypothesis that the association of urate gout and CPPD crystal deposition disease is based on the nucleating potential of MSU crystals for CPPD crystal growth. In contrast, the HA crystal structure did not appear to serve as a nucleating agent for CPPD crystals. However, HA crystals did serve as effective traps for PPi-4 ions and their presence led to more stable CPPD crystal growth
Bidding Game Valuations of Congestion Costs in Winter Sports Areas
During the last three decades, there has been a significant growth in the outdoor recreation industry. In 1969, there were 17.6 million visits to national parks, and by 1978, that number had increased to 283.1 million (Gregory, 1972; U.S. Dept. of Commerce, 1979). Similarly, visits to national forests grew from 5 million in 1925 to over 147 million in 1965 (Clawson and Knetsch, 1966)
Modified Chaplygin Gas and Constraints on its B parameter from CDM and UDME Cosmological models
We study Modified Chaplygin Gas (MCG) as a candidate for dark energy and
predict the values of parameters of the gas for a physically viable
cosmological model. The equation of state of MCG () involves three parameters: , and . The
permitted values of these parameters are determined with the help of
dimensionless age parameter () and Data. Specifically we
study the allowed ranges of values of B parameter in terms of and
( is defined in terms of the constants in the theory). We
explore the constraints of the parameters in Cold Dark Matter(CDM) model and
UDME(Unified Dark Matter Energy) model respectively.Comment: 5 pages, 10 fig
Calcium Pyrophosphate Crystal Deposition: A Kinetic Study Using a Type I Collagen Gel Model
Calcium pyrophosphate dihydrate (CPPD) crystal deposition disease is characterized by deposits of triclinic (t) and monoclinic (m) CPPD crystals in articular and fibrocartilage. Many investigators have attempted to model CPPD crystal growth using both solution and a variety of gel systems. We have investigated the effect of type I collagen fibrils on CPPD crystal nucleation and growth using an ionic diffusion model. Collagen was isolated from porcine menisci using a pepsin solubilization procedure and gelled in three layers, with one containing 10 mM pyrophosphate (PPi) plus physiologic ions, the middle containing only the ions, while the third contained 25 mM Ca plus physiologic ions. Initially, amorphorous calcium pyrophosphate formed at the Ca-PPi interface. Monoclinic CPPD crystallized in 6 weeks when the [Ca] was between 2 and 3 mM and the [PPi] was between 50 and 75 μM. At 13 weeks, t-CPPD formed when the [Ca] was also between 2 and 3 mM, but the PPi was less than 25 μM. One of the most striking differences between this system and all previous solution and gel model systems is the total absence of orthorhombic calcium pyrophosphate tetrahydrate (o-CPPT) from the gels made of collagen fibrils in near native conformation. Further, crystals of t-CPPD appear as large single crystals with the classic prismatic growth habit observed in vivo, and crystals of m-CPPD also evidence the in vivo rod habit. In contrast, the crystal growth habits of t-CPPD, m-CPPD, and o-CPPT grown in all of the other model systems never matched that observed in vivo. When compared to the previous studies, these results, particularly the crystal growth habit data, suggest that the native collagen fibrils themselves can nucleate CPPD crystal formation
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Microwave Treatment as a Pesticide Alternative for Stored-Products
This CRADA was a continuation of earlier work with Micro-Grain, Inc. to develop power, high frequency microwave treatment process to treat insect infested grain. ORNLs role was as a subcontractor to Micro-Grain's Phase II SBIR project funded by the US Department of Agriculture. The primary objective was to develop a commercial scale prototype unit capable of treating infested grain at flow rates approaching 1 kg/sec, which is required to be viable in the grain handling industry. A flow rate of {approx} 0.12 Kg/second was demonstrated at 20 kW microwave power level with 100% kill rate. The system is capable of 200 kW however waveguide arcing due to grain dust in the waveguide limited the power to 20 kW during the tests. Development tasks performed during the project included modification of an existing high-power microwave exposure facility to uniformly process large grain samples at high flow rates and improved instrumentation to detect grain flow and uniformity. Microwave processing tasks include a series of controlled exposure tests using infested grain samples provided and analyzed by the University of Oklahoma. Grain samples were infested with red flour beetles which proved the most difficult to kill in earlier tests. Most of the samples processed resulted in quite successful kill rates and a maximum grain temperature of 46 C. The facilities utilized at ORNL are located in the Fusion Energy building (9201-2 at Y-12) and include the 28 GHz 200 kW CW high power microwave facility and microwave test equipment associated with the FED Microwave Development Laboratory in 9201-2. An improved microwave exposure chamber and grain flow control and handling equipment were designed and build as a joint effort between Micro-Grain and ORNL. A number of insect infested grain tests were successfully performed although the higher power, higher flow rates were limited by arcing in the microwave waveguide and damage to the gyrotron output window. Test results and the overall performance of the applicator system are very favorable for continued development of the concept. Further tests were performed in a large high power 2.45 GHz microwave applicator in batches. These samples were also quite effectively treated which supports the concept that a lower cost, lower frequency microwave system might be more successful due to the improved economics and simpler operation and maintenance of the low frequency system. Follow-on work is still possible however the untimely death of Steve Halverson, founder of Micro-grain, has essentially brought the development work to a close for now. Micro-Grain is being run by relatives at a low level who are not actively pursuing further funding
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