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PubMed2001

Process of calcification on artificial materials.

CaO, SiO2-based glasses form the bonelike apatite on their surfaces in an acellular simulated body fluid (SBF) with ion concentrations nearly equal to those of the human blood plasma. The apatite formation of the former glasses is attributed to the catalytic effect of the Si-OH groups, which are formed on their surfaces in SBF, for the apatite nucleation. The gels of SiO2, TiO2, ZrO2, Ta2O5, and Nb2O5 formed the apatite on their surfaces in SBF, but Al2O3 gel did not. This indicates that the Ti-OH, Zr-OH, Ta-OH, and Nb-OH groups besides the Si-OH groups are also effective for the apatite nucleation, but Al-OH groups are not effective. Apatite formation on self-assembled monolayer terminated with various functional groups in SBF showed that COOH and H2PO4 groups are also effective for the apatite nucleation. All these groups are negatively charged around pH 7.40. Their apatite nucleating ability is varied with their arrangements. Among the Ti-OH groups, those in anatase structure are most effective for the apatite nucleation. Transmission electron microscope attached with energy dispersive X-ray spectrometer showed that these functional groups induce the apatite nucleation not directly, but through formation of their calcium compounds and subsequent formation of amorphous calcium phosphate with low Ca/P atomic ratios.

Apatites↗
PubMed1996

A time-resolved Fourier transformed infrared difference spectroscopy study of the sarcoplasmic reticulum Ca(2+)-ATPase: kinetics of the high-affinity calcium binding at low temperature.

We have used time-resolved Fourier transformed infrared difference spectroscopy to characterize the amplitude, frequency, and kinetics of the absorbance changes induced in the infrared (IR) spectrum of sarcoplasmic reticulum Ca(2+)-ATPase by calcium binding at the high-affinity transport sites. 1-(2-Nitro-4,5-dimethoxyphenyl)-N,N,N',N'-tetrakis [(oxycarbonyl)methyl]-1,2-ethanediamine (DM-nitrophen) was used as a caged-calcium compound to trigger the release of calcium in the IR samples. Calcium binding to Ca(2+)-ATPase induces the appearance of spectral bands in difference spectra that are all absent in the presence of the inhibitor thapsigargin. Spectral bands above 1700 cm-1 indicate that glutamic and/or aspartic acid side chains are deprotonated upon calcium binding, whereas other bands may be induced by reactions of asparagine, glutamine, and tyrosine residues. Some of the bands appearing in the 1690-1610 cm-1 region arise from modifications of peptide backbone carbonyl groups. The band at 1653 cm-1 is a candidate for a change in an alpha-helix, whereas other bands could arise from modifications of random, turn, or beta-sheet structures or from main-chain carbonyl groups playing the role of calcium ligands. Only a few residues are involved in secondary structure changes. The kinetic evolution of these bands was recorded at low temperature (-9 degrees C). All bands exhibited a monophasic kinetics of rate constant 0.026 s-1, which is compatible with that measured in previous study at the same temperature in a suspension of sarcoplasmic reticulum vesicles by intrinsic fluorescence of Ca(2+)-ATPase.

Acetates↗
PubMed2005

The effects of magnesium and ammonium additions on phosphate recovery from greenhouse wastewater.

Phosphorus recovery from greenhouse wastewater, using precipitation-crystallization, was conducted under three levels of calcium concentration, 304 mg/L (7.6 mmol/L), 384 mg/L (9.6 mmol/L), and 480 mg/L (12 mmol/L), and also with additions of ammonium and magnesium into the wastewater. Jar test results confirmed high phosphate removal, with more than 90% of the removal achieved with a pH as low as 7.7. Under the low calcium concentration, ammonium addition affected the chemical reactions at pH lower than 8.0, where struvite was produced; when the pH was raised to 8.8, other calcium compounds dominated the precipitation. Under the medium calcium concentration, ammonium and magnesium addition helped struvite precipitation in the low pH range. Hydroxyapatite (HAP) was the main product. Under the high calcium concentration, ammonium addition showed no effects on the precipitation.

Chemical Precipitation↗
PubMed1995

Carbon monoxide production from degradation of desflurane, enflurane, isoflurane, halothane, and sevoflurane by soda lime and Baralyme.

Anecdotal reports suggest that soda lime and Baralyme brand absorbent can degrade inhaled anesthetics to carbon monoxide (CO). We examined the factors that govern CO production and found that these include: 1) The anesthetic used: for a given minimum alveolar anesthetic concentration (MAC)-multiple, the magnitude of CO production (greatest to least) is desflurane > or = enflurane > isoflurane >> halothane = sevoflurane. 2) The absorbent dryness: completely dry soda lime produces much more CO than absorbent with just 1.4% water content, and soda lime containing 4.8% or more water (standard soda lime contains 15% water) generates no CO. In contrast, both completely dry Baralyme and Baralyme with 1.6% water produce high concentrations of CO, and Baralyme containing 4.7% water produces concentrations equaling those produced by soda lime containing 1.4% water. Baralyme containing 9.7% or more water and standard Baralyme (13% water) do not generate CO.3) The type of absorbent: at a given water content, Baralyme produces more CO than does soda lime. 4) The temperature: an increased temperature increases CO production. 5) The anesthetic concentration: more CO is produced from higher anesthetic concentrations. These results suggest that CO generation can be avoided for all anesthetics by using soda lime with 4.8% (or more) water or Baralyme with 9.7% (or more) water, and by using inflow rates of less than 2-3 L/min. Such inflow rates are low enough to ensure that the absorbent does not dry out.

Adsorption↗
PubMed2003

Alendronate zwitterions bind to calcium cations arranged in columns.

Alendronate is used clinically in the treatment of skeletal disorders, the mode of action depending on the adsorption to calcium hydroxyapatite crystals (bone). In the title compound, calcium 4-ammonium-1-hydroxybutylidene-1,1-bisphosphonate, Ca(2+).2C(4)H(12)NO(7)P(2)(-), alendronate is a zwitterion, possessing one negative charge on each PO(3) group and a protonated N atom. The zwitterion is disposed with its negative end facing the Ca(2+) ion, while its positive end is stretched in the opposite direction. The geometry of the carbon chain is all-trans, while the hydroxy group is approximately gauche. The Ca(2+) ion lies on a twofold axis parallel to b. The coordination sphere around the metal cation is octahedral and is determined by monodentate- and bidentate-coordinated alendronate zwitterions. The O.O bite distance is 3.080 (2) A. Coordinated Ca(2+) metal cations are arranged at the centre of a column running along c.

Journal Article↗
PubMed1997

High carboxyhemoglobin concentrations occur in swine during desflurane anesthesia in the presence of partially dried carbon dioxide absorbents.

BACKGROUND: Increased carboxyhemoglobin concentrations in patients receiving inhalation anesthetics (desflurane, enflurane, and isoflurane) have been reported. Recent in vitro studies suggest that dry carbon dioxide absorbents may allow the production of carbon monoxide. METHODS: The authors used high fresh oxygen flow (5 or 10 l/min) through a conventional circle breathing system of an anesthesia machine for 24 or 48 h to produce absorbent drying. Initial studies used 10 l/min oxygen flow with the reservoir bag removed or with the reservoir bag left in place during absorbent drying (this increases resistance to gas flow through the canister). A third investigation evaluated a lower flow rate (5 l/min) for absorbent drying. Water content of the absorbent and temperature were measured. Pigs received a 1.0 (human) minimum alveolar concentration desflurane anesthetic (7.5%) for 240 min using a 1 l/min oxygen flow rate with dried absorbent. Carbon monoxide concentrations in the circuit and carboxyhemoglobin concentrations in the pigs were measured. RESULTS: Pigs anesthetized with desflurane using Baralyme exposed to 48 h of 10 l/min oxygen flow (reservoir bag removed) had extremely high carboxyhemoglobin concentrations (more than 80%). Circuit carbon monoxide concentrations during desflurane anesthesia using absorbents exposed to 10 l/min oxygen flow (reservoir bag removed, 24 h) reached peak values of 8,800 to 13,600 ppm, depending on the absorbent used. Carboxyhemoglobin concentrations reached peak values of 73% (Baralyme) and 53% (soda lime). The water content of Baralyme decreased from 12.1 +/- 0.3% (mean +/- SEM) to as low as 1.9 +/- 0.4% at the bottom of the lower canister (oxygen flow direction during drying was from bottom to top). Absorbent temperatures in the bottom canister increased to temperatures as high as 50 degrees C. With the reservoir bag in place during drying (10 l/min oxygen flow), water removal from Baralyme was insufficient to produce carbon monoxide (lowest water content = 5.5%). Use of 5 l/min oxygen flow (reservoir bag removed) for 24 h did not reduce water content sufficiently to produce carbon dioxide with desflurane. CONCLUSIONS: An oxygen flow rate of 10 l/min for 24 h in a conventional anesthesia circuit can dry carbon dioxide absorbents sufficiently to produce extremely high levels of carbon monoxide with high carboxyhemoglobin concentrations in desflurane-anesthetized pigs. When the reservoir bag is in place on the anesthesia machine or when a lower oxygen flow rate (5 l/min) is used, carbon dioxide absorbent drying still occurs, but 24-48-h exposure time is insufficient to allow for carbon monoxide production with desflurane.

Adsorption↗
PubMed1997

Baralyme dehydration increases and soda lime dehydration decreases the concentration of compound A resulting from sevoflurane degradation in a standard anesthetic circuit.

UNLABELLED: Soda lime and Baralyme brand carbon dioxide absorbents degrade sevoflurane to CF2 = C(CF3)OCH2F, a potentially nephrotoxic vinyl ether called Compound A. Dehydration of these absorbents increases both the degradation of sevoflurane to Compound A and the degradation of Compound A. The balance between sevoflurane degradation and Compound A degradation determines the concentration of Compound A issuing from the absorbent (the net production of Compound A). We studied the effect of dehydration on the net production of Compound A in a simulated anesthetic circuit. Mimicking continuing oxygen delivery for 1, 2, or 3 days after completion of an anesthetic, we directed a "conditioning" fresh gas flow of 5 L/min or 10 L/min retrograde through fresh absorbent in situ in a standard absorbent system for 16, 40, and/or 64 h. The conditioned absorbent was subsequently used (without mixing of the granules) in a standard anesthetic circuit in which a 3-L rebreathing bag substituted for the lung. Metabolism was mimicked by introducing 250 mL/min carbon dioxide into the "lung," and the lung was ventilated with a minute ventilation of 10 L/ min. At the same time, we introduced sevoflurane in a fresh gas inflow of 2 L/min at a concentration sufficient to produce an inspired concentration of 3.2%. Because of increased sevoflurane destruction by the absorbent, progressively longer periods of conditioning (dehydration) and/or higher inflow rates increased the delivered (vaporizer) concentration of sevoflurane required to sustain a 3.2% concentration. Dehydration of Baralyme increased the inspired concentration of Compound A by up to sevenfold, whereas dehydration of soda lime markedly decreased the inspired concentration of Compound A. IMPLICATIONS: Economical delivery of modern inhaled anesthetics requires rebreathing of exhaled gases after removal of carbon dioxide. However, carbon dioxide absorbents (Baralyme/soda lime) may degrade anesthetics to toxic substances. Baralyme dehydration increases, and soda lime dehydration decreases, degradation of the inhaled anesthetic sevoflurane to the toxic substance, Compound A.

Anesthetics, Inhalation↗
PubMed1991

[Reactivity of sevoflurane with carbon dioxide absorbents--comparison of soda lime and Baralyme].

The reactivity of sevoflurane with carbon dioxide absorbents, soda lime and Baralyme which are commercially available carbon dioxide absorbents, was studied. A closed circuit system which was made only for this investigation was set up without rubber. Sevoflurane 5% was circulated for 17 hours. The circulated gas was analyzed by gas chromatography (GC) and degradation products were identified by a gas chromatography-mass spectroscopy (GC-MS) as fluoromethyl 2-methoxy-2, 2-difluoro-1-(trifluoromethyl) ethyl ether, fluoromethyl 2-methoxy-2-fluoro-1-(trifluoromethyl) vinyl ether, and its isomer. These degradation products of sevoflurane from soda lime and Baralyme were the same substances. The rate of degradation by soda lime was 0.88% +/- 0.306, while that by Baralyme was 3.40% +/- 0.501. Baralyme decomposed sevoflurane about four times more than soda lime. There are two possible explanations for these results. One is the Baralyme contains more potassium hydroxide than soda lime. The other is that soda lime absorbs sevoflurane more because it contains more silica.

Absorption↗
PubMed1995

Factors affecting the concentration of compound A resulting from the degradation of sevoflurane by soda lime and Baralyme in a standard anesthetic circuit.

Carbon dioxide absorbents, such as soda lime and Baralyme brand absorbent, convert sevoflurane to CF2 = C(CF3)OCH2F, a vinyl ether called "Compound A," whose toxicity raises concerns regarding the safety of sevoflurane in rebreathing circuits. Because an increased inflow rate to an anesthetic circuit decreases rebreathing, we assumed that an increased rate would proportionately decrease the concentration of Compound A. In the present report, we measured the Compound A concentration resulting from the action of wet (standard) soda lime and wet (standard) Baralyme on 2% sevoflurane in a model anesthetic circuit, using inflow rates (0.5, 1.0, 2.0, 4.0, and 6.0 L/min), ventilations (5 and 10 L/min), and carbon dioxide production/removal (200 and 400 mL/min) found in clinical practice. An increase in inflow rate decreased Compound A concentration to lower levels as inflow rate approached minute ventilation. At lower inflow rates, increasing duration of sevoflurane inflow increased the concentration of Compound A, a finding consistent with a progressive increase in absorbent temperature from absorption of carbon dioxide and consequently greater sevoflurane degradation. There was no material difference between Baralyme and soda lime in the concentrations of Compound A produced at a particular inflow rate. An increase in ventilation increased the concentration of Compound A, having a much greater effect at high rather than low inflow rates. An increase in amount of carbon dioxide absorbed also increased the concentration of Compound A. We conclude that inflow rate, ventilation, and carbon dioxide production are major determinants of the concentration of Compound A.

Absorption↗
PubMedDate not supplied

New treatment methods in verapamil poisoning: experimental studies.

The aim of this study was to evaluate the effectiveness of the treatment with 4-aminopyridine (4-AP, potassium channel inhibitor) and Bay K 8644 (calcium channel activator) in experimentally evoked verapamil poisoning in rats and to compare the results of this treatment with the effectiveness of widely accepted methods (adrenaline, calcium compounds). The experiment was carried out on male and female Wistar rats which were divided into 4 experimental (A, B, C, D) and a control (K) groups. Rats were anesthetized and the abdominal aorta was cannulated for mean arterial pressure and heart rate measurements while caudal vein was cannulated for drug administration. All animals were infused with verapamil (150 mg/kg/h) until 50% reduction of mean arterial pressure and/or heart rate was observed. After verapamil, control animals were given 0.9% NaCl solution and the other groups received 687.5 mg/kg/h of calcium glucolactobionicum (group A), 0.3 mg/kg/h of adrenaline (group B), 2 mg/kg/h of 4-AP (group C) or 2 mg/kg/h of Bay K 8644 (group D). The mean blood pressure and heart rate was checked and ECG was recorded every 10 min. A statistically significant decrease in mortality compared with the control group was observed in animals treated with adrenaline (p < or = 0.05), Bay K 8644 (p < or = 0.01) and 4-AP (p < or = 0.005). The treatment of experimentally evoked poisoning in rats using 4-AP or Bay K 8644 resulted in fast receding of poisoning symptoms: increase in blood pressure and heart rate, receding of bradyarrhythmia and return of sinus rhythm. The results of the study suggest the usefulness of 4-AP and Bay K 8644 in the treatment of verapamil poisoning.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

Long-duration, low-flow sevoflurane anesthesia using two carbon dioxide absorbents. Quantification of degradation products in the circuit.

BACKGROUND: Sevoflurane reacts with soda lime, generating degradation products. The concentrations of sevoflurane degradation products in a low-flow circuit have been reported for anesthesia times of less than 5 h. In this study, sevoflurane degradation products generated during low-flow anesthesia exceeding 10 h were examined. METHODS: Sixteen patients received sevoflurane anesthesia with a fresh gas flow rate of 11/min. In eight patients, soda lime was used as the CO2 absorbent; in the other eight patients, Baralyme was used. During anesthesia, the concentrations of degradation products in the circuit, the temperature of the CO2 absorbent, inspired and end-tidal sevoflurane concentrations, and the volume of CO2 eliminated by the patient were measured. Gas was sampled from the inspiratory limb of the circuit and analyzed by gas chromatography. RESULTS: Two degradation products, CF2 = C(CF3)-O-CH2F (compound A) and CH3OCF2CH(CF3)OCH2F (compound B), were detected. In the soda lime group, the individual maximum concentration of compound A was 23.6 +/- 2.9 (12.0-37.4) ppm. In the Baralyme group, the concentration was 32.0 +/- 2.3 (23.5-41.3) ppm. The individual maximum concentration of compound A in the Baralyme group was significant higher than A in the Baralyme group was significant higher than that in the soda lime group. Compound B was detected in two patients, reaching a maximum concentration of 0.2 ppm. The end-tidal sevoflurane concentration, temperature of the CO2 absorbent, and volume of CO2 eliminated by the patient were the same in both groups. CONCLUSIONS: The degradation products detected were at low concentrations in long-duration, low-flow anesthesia with sevoflurane. Baralyme produced higher concentrations of degradation products than soda lime.

Adsorption↗
PubMed2005

Temperatures in soda lime during degradation of desflurane, isoflurane, and sevoflurane by desiccated soda lime.

Rarely, fire and patient injury result from the degradation of sevoflurane by desiccated Baralyme. The present investigation sought to determine whether high temperatures also arose with sevoflurane use in the presence of desiccated soda lime. We desiccated soda lime by directing a 10 L/min flow of oxygen through fresh absorbent. Using 1140 +/- 30 g (mean +/- sd) of this desiccated absorbent, we filled a single standard absorber canister placed in a standard anesthetic circuit to which we directed a 6 L/min flow of oxygen containing 1.5 minimum alveolar concentration (MAC) desflurane or sevoflurane, or 3.0 MAC desflurane, isoflurane, or sevoflurane (with and without concurrent delivery of 200 mL/min carbon dioxide). In an additional test, 2 canisters (rather than a single canister) containing desiccated absorbent were used and 3.0 MAC sevoflurane was applied. A 3-L reservoir bag served as a surrogate lung, and we ventilated this lung with a minute ventilation of 10 L/min. With desflurane at 1.5 MAC or 3.0 MAC or isoflurane at 3.0 MAC temperatures increased in 20 to 40 min to a peak of 30 degrees C to 45 degrees C and then declined. With 1.5 or 3.0 MAC sevoflurane, temperatures increased to approximately 90 degrees C, after which temperatures declined. Concurrent delivery of carbon dioxide and sevoflurane did not increase the peak temperatures reached. The use of 2 canisters increased the duration but not the peak of increased temperature reached with 3.0 MAC sevoflurane. No fires resulted from degradation of any anesthetic.

Anesthetics, Inhalation↗
PubMed1996

Factors affecting production of compound A from the interaction of sevoflurane with Baralyme and soda lime.

Various alkali (e.g., soda lime) convert sevoflurane to CF2=C(CF3)OCH2F, a vinyl ether called "Compound A, " whose toxicity raises concerns regarding the safe administration of sevoflurane via rebreathing circuits. In the present investigation, we measured the sevoflurane degradation and output of Compound A caused by standard (13% water) Baralyme brand absorbent and standard (15% water) soda lime, and Baralyme and soda lime having various water contents (including no water). We used a flow-through system, applying a gas flow rate relative to absorbent volume that roughly equaled the rate/volume found in clinical practice. Both absorbents, at similar water contents, temperatures, and sevoflurane concentrations, produced roughly equal concentrations of Compound A. Dry and nearly dry absorbents produced less Compound A early in exposure to sevoflurane, and more later, than standard absorbents. Increases in temperature and sevoflurane concentration increased output of Compound A. Both absorbents, especially when dry, also destroyed Compound A, the concentration exiting from absorbent resulting from a complex sum of production and destruction. We conclude that the variability of concentrations of Compound A found in clinical practice may be largely explained by the inflow rate used (i.e., by rebreathing), sevoflurane concentration, and absorbent temperature and dryness. The effect of dryness is complex, with fresh dry absorbent destroying Compound A as it is made, and with dry absorbent that has been exposed to sevoflurane for a period of time providing a sometimes unusually high output of Compound A.

Absorption↗
PubMed1992

Factors affecting the rate of disappearance of sevoflurane in Baralyme.

The effects of temperature, water and Baralyme exhaustion on the rate of disappearance of sevoflurane in Baralyme were studied in an in vitro model. We found that the rate of disappearance of sevoflurane in Baralyme increased as the temperature increased and decreased as the concentration of water increased. The disappearance of sevoflurane also decreased in the presence of exhausted Baralyme compared with fresh Baralyme. The slower rate of disappearance of sevoflurane in Baralyme in the presence of water and Baralyme exhaustion suggests that the disappearance of sevoflurane may be self-limiting in the clinical setting.

Adsorption↗
PubMed2002

Comparison of Amsorb, sodalime, and Baralyme degradation of volatile anesthetics and formation of carbon monoxide and compound a in swine in vivo.

BACKGROUND: Consequences of volatile anesthetic degradation by carbon dioxide absorbents that contain strong base include formation of compound A from sevoflurane, formation of carbon monoxide (CO) and CO toxicity from desflurane, enflurane and isoflurane, delayed inhalation induction, and increased anesthetic costs. Amsorb (Armstrong Ltd., Coleraine, Northern Ireland) is a new absorbent that does not contain strong base and does not form CO or compound A in vitro. This investigation compared Amsorb, Baralyme (Chemetron Medical Division, Allied Healthcare Products, St. Louis, MO), and sodalime effects on CO (from desflurane and isoflurane) and compound A formation, carboxyhemoglobin (COHb) concentrations, and anesthetic degradation in a clinically relevant porcine in vivo model. METHODS: Pigs were anesthetized with desflurane, isoflurane, or sevoflurane, using fresh or partially dehydrated Amsorb, Baralyme, and new and old formulations of sodalime. Anesthetic concentrations in the fresh (preabsorber), inspired (postabsorber), and end-tidal gas were measured, as were inspired CO and compound A concentrations and blood oxyhemoglobin and COHb concentrations. RESULTS: For desflurane and isoflurane, the order of inspired CO and COHb formation was dehydrated Baralyme >> soda-lime > Amsorb. For desflurane and Baralyme, peak CO was 9,700 +/- 5,100 parts per million (ppm), and the increase in COHb was 37 +/- 14%. CO and COHb increases were undetectable with Amsorb. Oxyhemoglobin desaturation occurred with desflurane and Baralyme but not Amsorb or sodalime. The gap between inspired and end-tidal desflurane and isoflurane did not differ between the various dehydrated absorbents. Neither fresh nor dehydrated Amsorb caused compound A formation from sevoflurane. In contrast, Baralyme and sodalime caused 20-40 ppm compound A. The gap between inspired and end-tidal sevoflurane did not differ between fresh absorbents, but was Amsorb < sodalime < Baralyme with dehydrated absorbents. CONCLUSION: Amsorb caused minimal if any CO formation, minimal compound A formation regardless of absorbent hydration, and the least amount of sevoflurane degradation. An absorbent like Amsorb, which does not contain strong base or cause anesthetic degradation and formation of toxic products, may have benefit with respect to patient safety, inhalation induction, and anesthetic consumption (cost).

Absorption↗
PubMed1992

Quantification of the degradation products of sevoflurane in two CO2 absorbants during low-flow anesthesia in surgical patients.

Sevoflurane, a new inhalational anesthetic agent has been shown to produce degradation products upon interaction with CO2 absorbants. Quantification of these sevoflurane degradation products during low-flow or closed circuit anesthesia in patients has not been well evaluated. The production of sevoflurane degradation products was evaluated using a low-flow anesthetic technique in patients receiving sevoflurane anesthesia in excess of 3 h. Sevoflurane anesthesia was administered to 16 patients using a circle absorption system with O2 flow of 500 ml/min and average N2O flow of 273 ml/min. Preoperative and postoperative hepatic and renal function studies were performed. Gas samples were obtained from the inhalation and exhalation limbs of the anesthetic circuit for degradation product analysis and analyzed by gas chromatography/mass spectrometry for four degradation products. The first eight patients received sevoflurane anesthesia using soda lime, and the following eight patients received anesthesia using baralyme as the CO2 absorbant. CO2 absorbant temperatures were measured during anesthesia. Of the degradation products analyzed, only one compound [fluoromethyl-2, 2-difluoro-1-(trifluoromethyl) vinyl ether], designated compound A, was detectable. Concentrations of compound A increased during the first 4 h of anesthesia with soda lime and baralyme and declined between 4 and 5 h when baralyme was used. Mean maximum inhalation concentration of compound A using baralyme was 20.28 +/- 8.6 ppm (mean +/- SEM) compared to 8.16 +/- 2.67 ppm obtained with soda lime, a difference that did not reach statistical significance. A single patient achieved a maximal concentration of 60.78 ppm during low-flow anesthesia with baralyme. Exhalation concentrations of compound A were less than inhalation concentrations, suggesting patient uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed2006

In vivo study of novel biodegradable and osteoconductive CaO-SiO2-B2O3 glass-ceramics.

To evaluate the possibility of novel CaO-SiO2-B2O3 glass-ceramics (CS10B) as a new bone replacement material, we compared the biodegradation and osteoconduction properties of CS10B, hydroxyapatite (HA), and tricalcium phosphate (TCP). Porous CS10B implants were prepared by the polymer sponge method. L5-6 single-level posterolateral spinal fusions were performed on 30 New Zealand white male rabbits. The animals were divided into three groups by implant material: CS10B, HA, and TCP. Radiographs were performed every 2 weeks. All animals were euthanized 12 weeks after surgery. The ratio of the area occupied by the ceramics by final and initial radiographs was calculated using radiomorphometric analysis. Uniaxial tensile strength was determined from seven cases in each group. The ratio of the area occupied by HA (88.7%+/-16.1%) was significantly higher than the others (p<0.005), and the ratio of the area occupied by CS10B (28.2%+/-9.3%) was significantly lower than those of HA and TCP (37%+/-9.6%, p<0.05). The mean values of the tensile strengths of the CS10B (182.7+/-19.9 N) and HA (191.4+/-33.5 N) were significantly higher (p<0.05) than that of TCP (141.1+/-28.2 N). CS10B had a fusion mass tensile strength similar to that of HA. Histological analysis confirmed that CS10B was well incorporated into the fusion mass. These findings suggest that CS10B is a possible bone replacement material.

Animals↗