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Query: UMLS:C0026916 (MAC)
 5,226 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

By studying a group of organophosphorus compounds (PhOC), system of methods for developing models of chronic intoxication was approved, the purpose of which was to establish safe levels of chemical pollutants in the water. The magnitudes of threshold doses (TD) and ineffective doses (MID) were obtained by using MACrv (maximum admissible concentrations of substances in the air of industrial plants) and TLV [indices of admissible levels of substances in the air of industrial plants (USA standards)]. In compiling estimated and experimentally established MAC for 21 substances, variations were recorded within the range of 2-10 times. Forecasting on the basis of ED50, Elim and other measures during 5-20 day experiments made it possible to estimate threshold and inactive doses of PhOC during chronic intoxication, as well as to determine a cumulative coefficient and distribute these compounds into two series, according to the degree of their hazard. This project made it possible to determine cumulative properties simultaneously and forecast the chronic toxicity of the PhOC group under investigation.
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PMID:System of accelerating methods of evaluating toxicity and hazardous properties of substances. 44 59

The authors sought to test whether a deviation existed for the correlation between anesthetic potency and the oil/gas partition coefficient at an extreme of lipid solubility. For thiomethoxyflurane, the sulfur analog of methoxyflurane, the oil/gas partition coefficient was 7230 +/- 50 SEM, and MAC (minimum alveolar concentration of thiomethoxyflurane required for anesthesia) in 4 dogs was 0.035 +/- 0.008 percent of 1 atm. This agrees with the potency predicted by the lipid solubility, although thiomethoxyflurane is 7 1/2 times more potent than methoxyflurane, to date the most potent available anesthetic. Thiomethoxyflurane water/gas and blood/gas partition coefficients were 5.4 +/- 0.3 and 68.1 +/- 1.5, respectively. The latter coefficient accords with the prolonged recovery associated with this agent. Renal and hepatic blood chemistries measured on the 1st and 7th days following anesthesia showed only small changes from preanesthetic values.
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PMID:Some characteristics of an exceptionally potent inhaled anesthetic: thiomethoxyflurane. 55 38

Two methods were applied to evaluation of acelysine level. Spectrophotometric one was based on reaction with p-nitrophenyldiasonium and evaluation of the product optic density at 510 nm. The second was chromatography in thin layer, where a mixture of n-butanol, formic acid and water was used as an eluent and 0.2% ninhydrin solution in butanol and 3 ml of ice acetic acid (60-70 degrees C) served as a developer. Both methods are supposed to evaluate acelysine level in the air of working area, when a half of MAC and admixtures are present.
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PMID:[Photometric and chromatographic methods of measuring the concentration of acelysin in the air of a work area]. 130 95

"Zharilek" preparation MAC in the water reservoirs was approved at the level of 0.01 mg/l. The preparation is referred to the 3rd class of hazard by the complex toxicological study.
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PMID:[An experimental validation of the MPEL for the Zharilek mixture and its component constituents]. 142 83

References to different methods of cobalt detection in biologic material are given. Polarographic detection of cobalt in human urine and animal biologic material worked out by authors was used for evaluation of biologic MAC. Biologic material was limed by nitric and sulfuric acids. Sulfuric acid was carefully distilled off the burnt material. Mineralized material was dissolved in 10 ml of 1N hydrochloric acid, filtered and again steamed into moist salts. 2.5 ml of water, 0.5 ml of dimethylglyoxime (0.02 M), 2 ml of Na4P2O7 (0.2 M) and 5 ml of buffer solution (0.1 M NH4Cl and NH4OH) were added to limed mineral, than pH was driven to 9 by 1 = 2 drops of ammonia solution and after blowing through, the specimen was exposed to polarography in alternating current. ++Redox potential of cobalt is 1.18 V. The method can be used for detection of cobalt in urine of workers contacting with the stated metal. Sensitivity of the method is 0.02 Mkg/ml.
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PMID:[Polarographic analysis of cobalt in biological specimens]. 147 28

Although suppression of thermoregulatory mechanisms by anesthetics is generally assumed, the extent to which thermoregulatory responses are active during general anesthesia is not known. To evaluate the effect of anesthetics on thermoregulation, we investigated the threshold body core temperatures to induce peripheral cutaneous vasoconstriction and shivering in spontaneously breathing rabbits. Rabbits are anesthetized with halothane at 0.05, 0.2 and 0.4 MAC (minimum alveolar concentration). Internal whole body cooling was performed by perfusing the cool water through an intestinal U-shaped thermode placed in the colon. Core (esophagus) and peripheral (ear) temperatures were measured with thermistors. The esophageal temperatures at the beginning of peripheral cutaneous vasoconstriction and shivering induced by internal whole body cooling were determined. Peripheral cutaneous vasoconstriction was not significantly affected by halothane. However, the incidence of shivering was significantly decreased by halothane dose-dependently. Threshold of shivering (37.3 +/- 0.8 degrees C) was significantly lower than that of peripheral cutaneous vasoconstriction (38.9 +/- 1.1 degrees C). We conclude that the halothane can exert an influence on shivering.
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PMID:[Effect of halothane on the peripheral cutaneous vasoconstriction and shivering induced by internal body cooling in rabbits]. 155 64

We describe a pseudoepidemic due to nontuberculous mycobacteria contaminating the water tank of a machine used to clean and disinfect fiberoptic endoscopes. Forty-six bronchoscopies performed on 41 patients during a six-month period yielded 16 specimens positive for acid-fast bacilli (AFB). One specimen showed Mycobacterium avium complex from an AIDS patient and one, M tuberculosis from a patient with active cavitary tuberculosis. In four patients, only the smears showed AFB; subsequent cultures remained negative. Of the rest, seven contained M chelonae and three M gordonae, all in patients with no clinical signs of mycobacterial disease. Two of the three M gordonae isolates represented laboratory contamination from an antimicrobial solution in a culture medium. Four patients in the beginning of the pseudoepidemic were treated for presumed tuberculosis until negative culture results were available. Control of the "outbreak" was achieved by regular disinfection of the implicated water tank in the cleaning machine. Contamination of bronchoscopes with nontuberculous mycobacteria can lead to unnecessary diagnostic and therapeutic interventions.
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PMID:Pseudoepidemic of nontuberculous mycobacteria due to a contaminated bronchoscope cleaning machine. Report of an outbreak and review of the literature. 158 79

Sensitive HPLC-UV methodology has been developed and validated for quantitating rifabutin, an antimycobacterial, and its 25-desacetyl metabolite, LM-565, in human plasma and urine. The HPLC separation for both plasma and urine samples was performed on an ODS, 5-microns, reverse-phase column (25 cm x 4.6-cm ID) using a mobile phase of acetonitrile/0.05 M potassium phosphate, pH 4.2, with triethylamine, (38:61.5:0.5, v/v), at a flow rate of 1.0 ml/min. The separation eluate was monitored by absorbance at 275 nm. Plasma samples (1 ml) were spiked with an internal standard (medazepam), buffered at pH 7.4 and extracted with 80:20 (v/v) hexane:ethyl acetate, and then back extracted with acidified water (0.05 M H3PO4). Linearity was established between 5.0-800 and 2.5-400 ng/ml for rifabutin and LM-565, respectively. Intraday imprecision for rifabutin and LM-565 plasma quality controls prepared at 7.3 and 3.2 ng/ml, respectively, was less than 15% relative standard deviation (RSD). Absolute recovery for parent drug and metabolite, from plasma, was greater than 90% throughout the respective dynamic ranges and greater than 70% for medazepam. Urine samples (1 ml) were acidified with 50 microliters of 3.6 M H2SO4 and diluted with 0.1 M ammonium acetate. Linearity was established between 100 and 5000 ng/ml for both rifabutin and LM-565. Intraday imprecision for a urine control at 200 ng/ml was less than or equal to 12% RSD for either component. The method is currently being used to support Phase I kinetics program for rifabutin in prophylaxis of MAC infection of AIDS patients. Application of this method to a bioavailability assessment is presented.
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PMID:A sensitive method for quantitation of rifabutin and its desacetyl metabolite in human biological fluids by high-performance liquid chromatography (HPLC). 166 4

Threshold concentrations of the flotation reagent EFK-1 in the water of reservoirs at 0.8 mg/l and 10.0 mg/l for organoleptic and total sanitary indices, respectively, were reported. Dl50 was 7469 mg/kg. The MAC of 0.8 mg/l for EFK-1 in the water of reservoirs (the limiting sign is organoleptic) was proposed.
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PMID:[Substantiation of maximum permissible water level of the flotation reagent EFK-1]. 181 35

Results of complex studies suggest 0.5 mg/l as the MAC for acetoacetic acid methylin in the water of reservoirs; the limiting indicator of harmfulness is sanitary-toxicological. The second class of danger.
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PMID:[Hygienic evaluation and standardization of ester level in reservoir water]. 183 17


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