Effect of histamine H2-receptor antagonist on the phosphorus-binding abilities of calcium carbonate and calcium lactate in hemodialysis patients.
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The effect of histamine H2-receptor antagonist (famotidine) on the phosphorus-binding abilities of calcium carbonate and calcium lactate were examined in 13 chronic hemodialysis patients. In seven patients receiving calcium carbonate, famotidine (20 mg/d) was given because of gastroduodenal disorders, and calcium carbonate was replaced with calcium lactate as a phosphorus binder after 4 wk of treatment with famotidine. With the 4-wk administration of famotidine accompanied by calcium carbonate, the serum phosphorus level increased from 6.3+/-0.9 to 7.1+/-0.5 mg/dl (P<0.05). However, with the substitution of calcium lactate, the serum phosphorus level decreased significantly when compared to that before substitution (6.3+/-0.2 and 6.0+/-0.9 mg/dl after 4 and 8 wk of substitution, respectively), despite continued administration of famotidine. Serum calcium, creatinine, alkaline phosphatase, high sensitive parathyroid hormone, blood urea nitrogen, arterial blood pH, and bicarbonate were not significantly altered during the trial period. In six control patients treated with calcium carbonate alone, there were no statistical changes in serum calcium and phosphorus levels after substitution of calcium lactate for calcium carbonate. These results suggest that famotidine significantly affects the phosphorus-binding ability of calcium carbonate, but not that of calcium lactate. A careful observation of changes in the serum phosphorus level should be required in hemodialysis patients receiving calcium carbonate and histamine H2-receptor antagonists. Calcium lactate may be useful as a phosphorus binder in such hemodialysis patients. (+info)
Intravascular ultrasound combined with Raman spectroscopy to localize and quantify cholesterol and calcium salts in atherosclerotic coronary arteries.
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Coronary intravascular ultrasound (IVUS) can assess arterial wall architecture and localize large intravascular deposits, but it does not provide quantitative chemical information, which is essential in the evaluation of atherosclerotic lesions. Previously, it has been shown that Raman spectroscopy can be used to accurately quantify the relative weights of cholesterol, calcium salts, triglycerides, and phospholipids in homogenized arterial tissue. In the present study, we explore some benefits of combining IVUS and Raman spectroscopy to evaluate the intact arterial wall. IVUS images were collected in vitro from human coronary arterial segments in various stages of disease (n=7). The images were divided into radial segments (11 to 28 per image, 332 in total), each of which was classified visually as calcified or noncalcified tissue. The arteries were opened longitudinally, and Raman spectra were collected from locations at 0. 5-mm intervals across the arterial luminal circumference. The spectra were used to calculate the chemical composition of the arterial wall at the examined locations. Generally, locations containing large amounts of calcium salts, as determined with Raman spectroscopy, were classified as calcified with IVUS. However, small calcific deposits (<6% of weight) were not readily detected with IVUS. The amounts and location of cholesterol determined with Raman spectroscopy were correlated closely with the presence of cholesterol observed by histochemistry, but these deposits could not be located accurately by IVUS. The combination of Raman spectroscopy and IVUS applied in vitro provides detailed information about the amount and location of calcific deposits and lipid pools in atherosclerotic plaques. Future advances in optical fiber technology may allow simultaneous collection of Raman spectra and IVUS images through the same catheter in vivo. (+info)
Compound A does not accumulate during closed circuit sevoflurane anaesthesia with the Physioflex.
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We have investigated inspiratory and end-tidal gas composition during sevoflurane anaesthesia in a closed circle system with continuous gas flow (70 litre min-1, Physioflex) to determine possible accumulation of sevoflurane degradation products. During five abdominal operations in adults lasting more than 2 h, anaesthesia was maintained with an end-tidal concentration of 2% sevoflurane in 40% oxygen-air. The circle included an absorbing canister filled with 1 litre of fresh soda lime. Samples were obtained at the end of an expiration from the tracheal tube and from the inspiratory limb before, and at selected times after, addition of sevoflurane. The temperature of soda lime was 24.7 +/- 0.7 degrees C at the beginning and reached a maximum of 31.2 +/- 1.0 degrees C after 20-30 min, followed by a plateau. Inspiratory compound A (CH2F-O-C(= CF2)(CF3)) 3-8 ppm was detected after 10 min, but did not accumulate in the circle over 2 h without flushing. Expired concentrations were consistently lower with 1.5-3 ppm signalling absorption by patients. Calculated total amounts absorbed over 2 h varied between 2.0 and 7.2 ppm h. Other degradation products such as compound B or methanol were not detected. In summary, we did not detect sevoflurane metabolites with soda lime in significant amounts during closed circle anaesthesia with the Physioflex. The observed concentrations of compound A were below the threshold of nephrotoxicity in rats by a factor of more than 20. (+info)
Structure of bioactive glass and its application to glass ionomer cement.
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We prepared a new glass ionomer cement using bioactive CaO-P2O5-SiO2(-MgO) glass and investigated its setting process using FT-IR and MAS NMR analyses. The compressive strengths of the cements depended on the glass composition and a maximum strength of 33.3 +/- 4.7 MPa was obtained using cement with the glass composition of MgO:4.6, CaO:44.9, SiO2:34.2 and P2O5:16.3% in weight. FT-IR analysis showed that the COOH group in the polyacrylic acid decreased and carboxylate ion (COO-Ca2+) increased after the setting reaction. A broad signal appeared around -82 ppm in 29Si MAS-NMR spectra of the glass and a new signal corresponding to hydrated silica gel formation appeared around -102 and -111 ppm after setting. This suggests that Ca2+ was released from the glass powder to form carboxylate salt and that a degree of polymerization in the silicate network increased. The setting mechanism of the cement was found to be essentially the same as in conventional glass ionomer cement. (+info)
Comparison of compound A concentrations with sevoflurane anaesthesia using a closed system with a PhysioFlex anaesthesia machine vs a low-flow system with a conventional anaesthesia machine.
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Sevoflurane anaesthesia was conducted using a totally closed circuit PhysioFlex anaesthesia machine (PhysioFlex group) or with a standard Modulus CD anaesthesia machine (Modulus group) (n = 8 in each group). The PhysioFlex was used under closed system conditions and the Modulus was used under low-flow system conditions (flow rate 1 litre min-1). Concentrations of sevoflurane degradation products and the temperature of soda lime were compared. Degradation products in the circuit were measured hourly, and the temperature of soda lime was monitored. The only degradation product detected was CF2 = C(CF3)-O-CH2F (compound A). Maximum concentrations of compound A were significantly lower (median 8.5 (range 5.4-15.9) ppm) in the PhysioFlex than in the Modulus group (21.2 (16.5-27.4) ppm) (P < 0.05). The maximum temperature of soda lime was also significantly lower in the PhysioFlex group (35.3 (32.1-36.3) degrees C vs 44.6 (43.0-47.1) degrees C, respectively) (P < 0.05). Hourly compound A concentrations were lower in the PhysioFlex group than in the Modulus group. End-tidal sevoflurane concentrations during measurement of degradation products were not different between groups. Therefore, use of the totally closed PhysioFlex system may significantly reduce compound A concentrations compared with low-flow anaesthesia using a standard anaesthesia machine. (+info)
Porous apatite-wollastonite glass-ceramic as an intramedullary plug.
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We evaluated the efficacy and biocompatibility of porous apatite-wollastonite glass ceramic (AW-GC) as an intramedullary plug in total hip replacement (THR) for up to two years in 22 adult beagle dogs. Cylindrical porous AW-GC rods (70% porosity, mean pore size 200 microm) were prepared. Four dogs were killed at 1, 3, 6 and 12 months each and six at 24 months after implantation. Radiological evaluation confirmed the efficacy of porous AW-CG as an intramedullary plug. Histological evaluation showed osteoconduction at one month and resorption of the porous AW-GC, which was replaced by newly-formed bone, at 24 months. Our findings indicate that porous AW-GC can be used clinically as an intramedullary plug in THR. (+info)
21st-century endodontics.
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BACKGROUND: Endodontics as a discipline has offered patients the opportunity to maintain their natural teeth. As the population expands and ages, the demand for endodontic therapy can be expected to increase as patients seek dental options to keep their teeth for a lifetime. CLINICAL IMPLICATIONS: New materials, techniques and instruments are entering the market-place to assist dentists in providing patients with more predictable and reliable endodontic treatment. In addition, these new systems make the delivery of endodontic services more efficient. This article describes these advances in endodontic treatment for dentists interested in incorporating these advances into their clinical practice. (+info)
Water vapour in a closed anaesthesia circuit reduces degradation/adsorption of halothane by dried soda lime.
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Dry lime causes a loss of volatile anaesthetics by degrading and adsorbing them. Degradation produces toxic substances and heat. Rehydration of lime stops degradation. If humidified breathing gases rehydrate lime, closed anaesthesia-circuits may reduce the loss of anaesthetics. To test this hypothesis we ventilated a reservoir bag with PhysioFlex-devices using fresh (F) and dried (D) soda lime both in the presence (+H) and absence (-H) of halothane. We measured halothane delivery, humidity, temperature, and lime weight. Halothane was lost for 13 min in D + H. Humidity increased steeper with fresh lime, whereas absorbent weight increased more with dried lime; halothane increased both variables (F + H: 99%, 8 g; F - H: 93%, 6 g; D + H: 58%, 17 g; D - H: 24%, 15 g). Surprisingly, temperature remained constant, probably because of the high gas flow (70 litres min-1) generated inside the Physioflex. These findings indicate rehydration of dried lime by humid gases and a rapid cessation of the loss of halothane in the PhysioFlex. (+info)