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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↗
PubMed1983

In vivo rat bladder: a new model to screen spasmolytic compounds.

A model for in vivo screening of spasmolytic compounds of the rat urinary bladder has been developed. It is physiological, specific, and adaptable. A filling volume of the bladder of 0.6-1 ml proved to be optimal. Agonists such as acetylcholine, KCl and BaCl2 exerted almost identical spasmogenic effects on both the in vivo and the in vitro model (isolated rat bladder strip). Moreover, the antagonistic effects of atropine, N-butylscopolammonium bromide, or flavoxate hydrochloride were directly comparable between the two models. Intravenously administered atropine was shown to be effective immediately; after intragastric application the maximum effect can not be observed until after 9 min. The in vivo rat bladder model presented is proposed to be a suitable method for advanced screening of spasmolytic compounds to include their absorption, biotransformation, and excretion.

Acetylcholine↗
PubMed1984

Severe allergic reaction: an unusual complication of barium enema.

This article describes a severe allergic reaction to a barium sulfate compound used during double-contrast colon examination. This unusual complication is probably induced by chemical agents used as additives in the commercially available barium preparations. The pertinent literature is briefly reviewed.

Adult↗
PubMed1998

A study of retentive filler and its use in dentistry.

OBJECTIVE: The purpose of this study was to develop a fine compound inorganic filler with special surface microstructure (called retentive filler or RF) and to investigate its use in composite resin and synthetic resin teeth. METHODS: Barium silicate glass and fine silicon dioxide or barium silicate glass were mixed and sintered, then dispersed and classified by sedimentation. The surface microstructure and the particle size distribution of retentive filler were surveyed, and the mechanical properties of the composite resin and the resin tooth material reinforced with RF were tested. RESULTS: Scanning electron microscopy showed that the surface of RF particles is distinguished for its retentive contour microstructure. The particle size of RF is smaller than 3 microns. The mechanical properties of composite resin reinforced with RF are better than that of composites containing normal fillers, and the wear resistance of the resin tooth material containing RF is better than that of normal synthetic resin. CONCLUSIONS: The RF can be successfully prepared by the technological process in this study. Because of the special surface microstructure, RF has a good bonding to the resin matrix. The testing results suggest that it is feasible to improve the mechanical properties, especially the wear resistance of the composite resin and resin teeth, by using retentive filler.

Barium Compounds↗
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↗
PubMed1976

[Exposed lead dioxide candles analyzed by a volumetric method, carried out as laboratory and field tests in Innsbruck (author's transl)].

Working up a great number of "lead-Dioxide-Candles" it took much less time to determine sulphate by a method of volumetric analysis with Ba(ClO4)2 and thoron or methylsulfonazo III as indicators compared with the so far used gravimetric determination of sulphate. With some training everybody will be able to make out the exact endpoint of the titration using thoron as indicator. The limits of error and the results gained from field-trials are shown. The possibilities of making statements of hygienically regional planning are discussed.

Air Pollutants↗
PubMed1986

Turnover and storage of newly synthesized adenine nucleotides in bovine adrenal medullary cell cultures.

The adenine nucleotide stores of cultured adrenal medullary cells were radiolabeled by incubating the cells with 32Pi and [3H]adenosine and the turnover, subcellular distribution, and secretion of the nucleotides were examined. ATP represented 84-88% of the labeled adenine nucleotides, ADP 11-13%, and AMP 1-3%. The turnover of 32P-adenine nucleotides and 3H-nucleotides was biphasic and virtually identical; there was an initial fast phase with a t1/2 of 3.5-4.5 h and a slow phase with a half-life varying from 7 to 17 days, depending upon the particular cell preparation. The t1/2 of the slow phase for labeled adenine nucleotides was the same as that for the turnover of labeled catecholamines. The subcellular distribution of labeled adenine nucleotides provides evidence that there are at least two pools of adenine nucleotides which make up the component with the long half-life. One pool, which contains the bulk of endogenous nucleotides (75% of the total), is present within the chromaffin vesicles; the subcellular localization of the second pool has not been identified. The studies also show that [3H]ATP and [32P]ATP are distributed differently within the cell; 3 days after labeling 75% of the [32P]ATP was present in chromaffin vesicles while only 35% of the [3H]ATP was present in chromaffin vesicles. Evidence for two pools of ATP with long half-lives and for the differential distribution of [32P]ATP and [3H]ATP was also obtained from secretion studies. Stimulation of cell cultures with nicotine or scorpion venom 24 h after labeling with [3H]adenosine and 32Pi released relatively twice as much catecholamine as 32P-labeled compounds and relatively three times as much catecholamine as 3H-labeled compounds.

Adenine Nucleotides↗
PubMed2000

Neutral bidentate organophosphorus compounds as novel ionophores for potentiometric membrane sensors for barium(II).

Bis(diarylphosphine oxide) naphthalene compounds are used as novel ionophores in plasticized poly(vinyl chloride) matrix membrane sensors for barium ions. The most favorable sensor was 1,2-bis(diethylphenylphosphine oxide)naphthalene containing potassium tetrakis(4-chlorophenyl)borate as lipophilic salt and o-nitrophenyloctyl ether as plasticizer for ion-selective electrode membrane construction. The electrode showed excellent properties. It gave a linear response with a Nernstian slope of 30 mV per decade within the concentration range 10(-1)-10(-5) mol L(-1) BaCl2. The electrode exhibits a high selectivity towards Ba2+ with respect to Li+, Na+, K+, Rb+, Cs+, NH4+, Ag+, Mg2+, Ca2+, Sr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, Al3+, La3+, and Ce3+ ions. The electrode response was stable over a wide pH range (3-11). The lifetime of the electrode was about 2 months. It was successfully applied to the determination of Ba2+ contents in some rocks.

Journal Article↗
PubMed1989

A patch-clamp study: secretagogue-induced currents in rat peritoneal mast cells.

Ca2+ entry through plasma membrane has been considered to play a significant role in elevating cytosolic free Ca2+ concentrations during stimulus-secretion coupling in mast cells, but electrophysiological evidence of the Ca2+ channels is lacking. We examined the properties of secretagogue (compound 48/80)-induced currents in rat peritoneal mast cells, using the patch-clamp technique. In the whole cell recordings, the addition of compound 48/80 induced transient currents that were suppressed by Cd or reduced by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). In Ringer solution containing 2 mM Ca2+, the current-voltage relation was fairly linear from -100 to 50 mV and the reversal potential was 14 +/- 10.1 mV (n = 9). When the external Ca2+ was approximately 1 microM, the compound 48/80-induced currents were marginal, but readmission of Ca2+ or Ba2+ to the bath solution led to an appearance of the currents. In the cell-attached patches, the stimulation enhanced the activity of inward current mediated by Ba2+. The unitary inward Ba2+ current was characterized by the unitary conductance of 10.5 +/- 2.0 pS (n = 10) with isotonic BaCl2 pipette solution, the extrapolated reversal potential of 60.7 +/- 16.0 mV (n = 10) positive to the resting membrane potentials. The percent open time of the inward Ba2+ current channel was not appreciably changed by voltage. In some whole cell recordings, an increase in openings of the cation-selective channel (20-45 pS) was identified in the stimulated cells. When the external Na+ was completely replaced by choline+, the compound 48/80-induced currents had a fairly linear current-voltage relation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2001

Studies on calcium antagonist activities of 2-ethyl-3-carbmethoxy-4-aryl- 5-oxo-6,6-dimethyl-1,4,5,6,7,8-hexahydroquinoline derivatives.

In this study, 23 new compounds having 2-ethyl-3-carbmethoxy-4-aryl-5-oxo-6,6-dimethyl-1,4,5,6,7, 8-hexahydroquinoline structure have been synthesised and screened for their calcium antagonistic activities. The structure of the compounds were characterised by IR, 1H-NMR, 13C-NMR, mass spectroscopy and elemental analyses. The calcium antagonistic activities of the compounds were determined by the tests performed on isolated rat ileum and lamb carotid artery. Although none of the synthesized compounds were as active as nicardipine in isolated rat ileum, the compounds 9, 10 and 19 have shown high activity. In screening studies on lamb carotid artery, compounds 10, 14 and 19 have been found active at a concentration of 10(-4) mol/l.

Animals↗