Verification of Intoximeter 3000 breath alcohol concentration by magnesium perchlorate tube method in long-term field program.

The anhydrous magnesium perchlorate (MPT) breath alcohol sample collection tube was analyzed by gas chromatography (GC) to verify paired breath alcohol concentrations obtained from 18 Intoximeter 3000 (IR) instruments under normal conditions of use. This study compares the accuracy, precision, and reliability of actual driving-while-intoxicated (DWI) IR breath alcohol evidence gathered by field law enforcement personnel with the GC results of the MPT alcohol analysis. The IR and MPT-GC breath alcohol concentration results from a total of 1024 individuals were determined. Results of 530 (51.7%) MPT-GC breath alcohol analyses deviated within +/- 0.010 g/210 L from their paired IR breath alcohol result; 817 (79.7%) and 945 (92.3%) MPT-GC breath alcohol analyses deviated within +/- 0.020 and +/- 0.030 g/210 L, respectively. Confidence interval limits at various probability levels are tabulated and show expected reliability of a single predicted IR breath alcohol concentration from the IR on MPT-GC linear regression analysis.

Electrical impedance measurements in the reading and monitoring of broth dilution susceptibility tests.

Electrical impedance changes in the medium were studied during traditional broth dilution tests. Tests involved clinical isolates of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Enterobacter sp., Klebsiella, and enterococcus and ten antibiotics. Minimal inhibitory concentration (MIC) values from overnight visual readings were compared with MIC values determined from electrical impedance end points, using inocula of 10(6) organisms per ml. Ninety-three percent of the results were within one twofold dilution of each other. When the impedance end point was determined at 6 h, this correlation was lowered to 34%. By increasing the initial electrical impedance inoculum 10-fold, the correlation between the 6-h impedance MIC and the overnight visual MIC was improved to 74%. Ampicillin, tetracycline, and polymyxin E results accounted for most discrepancies. Continuous monitoring of impedance changes suggested that better correspondence could be obtained by adjusting the end point criteria for the 6-h impedance MIC with different antibiotics. Electrical impedance methods for reading bacterial end points in automated clinical laboratory instruments appear promising.

Ageing of Neurospora crassa. II. Organic hydroperoxide toxicity and the protective role of antioxidant and the antioxygenic enzymes.

Cumene hydroperoxide and tert-butyl hydroperoxide at sublethal concentrations initially prevent growth of mycelia of wild-type Neurospora crassa, but after a time the cells grow at a subnormal steady-state rate. The antioxidant nordihydroguaiaretic acid protects unadapted cells from hydroperoxide inhibition, leading to a decrease in the time before growth begins, an increase in steady-state growth rate and an increase in biomass production. The results of growth transfer experiments and enzyme measurements indicated that the acquired resistance to the hydroperoxides is physiological and most likely involves the induction of the synthesis of the antioxygenic enzymes superoxide dismutase, glutathione peroxidase and glutathione reductase. Nordihydroguaiaretic acid normalizes the levels of activities of glutathione peroxidase and glutathione reductase during culture with hydroperoxide. Molecular-induced homolysis of the hydroperoxides, a process that is induced by unsaturated fatty acids of membrane lipids, leads to lipid autoxidation in a chain reaction which produces lipid hydroperoxides, which in turn decomposes to form more free radicals. Nordihydroguaiaretic acid, a well-known free radical scavenger, probably serves to minimize hydroperoxide decomposition, lipid autoxidation and molecular damage from free radicals, whereas the coupled enzyme system glutathione peroxidase and glutathione reductase minimizes these processes by decomposing the hydroperoxides to harmless alcohols. We suggest that either free radicals derived from these processes or some consequent non-radical products may serve as the inducers of this enzyme system, rather than the hydroperoxide substrates.

Respiration of wild type and extrachromosomal mutants of Neurospora crassa.

The specific rates of respiration of cells of wild type and four extrachromosomal mutants of Neurospora crassa were measured throughout the vegetative growth cycle. Two forms of respiration were observed: (i) cyanide sensitive; and (ii) cyanide resistant, salicyl hydroxamate sensitive. These two forms are called terminal and alternate, respectively. The former proceeds by the mitochondrial electron transfer chain and involves the cytochromes; the latter apparently proceeds by the initial portion of the electron transfer chain and does not involve cytochromes. Large and rapid changes of both the terminal and alternate respiratory activities occurred during the vegetative growth cycle. The kinetics of these changes in wild type were compared under some conditions which inhibit protein synthesis and others in which the nitrogen source was varied. The kinetics of the changes of the two forms of respiration of mutants differed from those normally exhibited by wild type, but with varied experimental conditions wild type could be made to resemble the mutants. The results of these studies are discussed in terms of a dynamic model of regulation of mitochondrial biogenesis in the coordination of the synthesis of mitochondrial proteins encoded by nuclear and mitochondrial genomes.

Glucose utilization and ethanolic fermentation by wild type and extrachromosomal mutants of Neurospora crassa.

Logarithmic growth rates, maximal biomass, specific glucose utilization rates, and ethanol accumulation were measured in aerobic cultures of wild type and extrachromosomal mutants of Neurospora crassa. Maximal biomass and ethanol accumulation of wild type and [mi-1] were proportional to the initial glucose concentration in the range of 2 to 10%. The specific rates of glucose utilization by the mutants were 13- to 20-fold greater than those of wild type in young cultures. The specific rates of glucose utilization by wild type, however, were increased threefold by increasing the ammonium ion concentration in the preculture medium. The suppressor gene f(+) suppressed the excessive glucose utilization and enhanced the growth rate and maximal biomass of [mi-1]. When the mutants were utilizing glucose at excessive rates, ethanol did not appear in the culture medium. Ethanol accumulation was maximum at stationary phase or thereafter, but there was little difference between the maxima of the mutants and wild type. The molar efficiency of the conversion of glucose to ethanol during the entire culture period of wild type and mutants was about 50% and, in the latter stages of fermentation, approached 100%. Replacement of ammonium ion by nitrate in the culture medium suppressed ethanol accumulation by wild type. The relationship of these results to previous observations on respiratory adaptation are discussed. We suggest that the Pasteur effect, the inhibition of fermentation by respiration, may be operative in N. crassa. Factors such as nitrogen source and concentration and oxygen tension, which may serve primarily to regulate the amount and form of respiration would, therefore, indirectly regulate fermentation. The mutants, although transiently deficient in terminal respiratory activity, do not accumulate more ethanol than wild type and, therefore, apparently do not ferment in excess to obtain additional adenosine 5'-triphosphate. We suggest that the excess activity of the alternate form of respiration of the mutants may be related to their excessive rate of glucose utilization by way of the pentose phosphate pathway and the oxidation of excess reduced nicotinamide adenine dinucleotide.

Inhibition of electron transport enzymes and cholinesterases by Endrin.

Two enzymes involved in mitqchondrial electron transport in the catfish,Ictalurus melas, have been shown to be inhibited by endrin. Succinate dehydrogenase and cytochrome oxidase were both inhibited, and the extent of inhibition depended ypon endrin concentration and the specific activity ef the enzyme preparation. No appreciable effect of endrin on acetylcholinesterase or NADH-cytochrome c reductase was seen. Binding to lipoprotein components essential for mitochondrial oxidation has been proposed as a logical site for endrin action.