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Digitale Medien

The influence of age on the electroretinogram and visual evoked potential (1985)

Wright, C. E. ; Williams, D. E. ; Drasdo, N. ; [weitere]

Springer

Documenta ophthalmologica 59 (1985), S. 365-384

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Details

ISSN: 1573-2622

Schlagwort(e): dark adapted ERG ; photopic ERG ; flash VEP ; pattern reversal VEP ; pattern onset-offset VEP ; ageing

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Changes in the ERG and VEP across the life span were investigated. The dark adapted and scotopic ERGs both showed a progressive increase in the implicit times of the A and B waves and a reduction in the amplitude of the AB configuration. There was also an increase in the implicit times of the oscillatory potentials of the photopic ERG. The flash and pattern onset-offset VEP both showed changes in waveform with age whilst the waveform of the pattern reversal VEP was constant. The amplitudes of the components of the flash and pattern reversal VEP were very high in the teenage group, but once reduced, were constant from the twenties onwards, showing no further consistent age changes. The latencies of the components of the pattern VEPs showed an increase with age which could be accounted for by the reduction in retinal illuminance due to the decrease in pupil diameter with age. However, the increase in the latency of the flash major positive (P2) component was greater than that expected from the decrease in retinal illuminance alone, suggesting that this is due to neural factors.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00159171

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Digitale Medien

Comparative chemical analysis of commercial creosotes and solvent refined coal-II materials by high resolution gas chromatography (1985)

Wright, C. W. ; Later, D. W. ; Wilson, B. W.

Weinheim : Wiley-Blackwell

Journal of High Resolution Chromatography 8 (1985), S. 283-289

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ISSN: 0935-6304

Schlagwort(e): Gas chromatography, GC ; Fused silica capillary columns ; Microbial mutagenicity ; Solvent refined coal ; Creosote oils ; Polyaromatic hydrocarbons ; Chemistry ; Analytical Chemistry and Spectroscopy

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: The chemical composition of a commercially available creosote was compared to a direct coal liquefaction product, i.e., solvent refined coal-II fuel oil blend (SRC-II FOB) using high resolution gas chromatography (HRGC). In addition, hydrogenated products of these materials were studied. Samples were fractionated by chemical class on neutral alumina. Those fractions previously shown to be the most mutagenic and tumorigenic in laboratory bioassays of coal-derived materials were analyzed and compared by HRGC and gas chromatography/mass spectrometry (GC/MS). Individual components were tentatively identified and quantitated. Although similar chemical components were present in the creosote and SRC-II FOB fractions studied, the creosotes had higher concentrations of heavy molecular weight materials and a lower ratio of alkylated to parent polycyclic aromatic compounds than the coal liquefaction products. The creosote samples also had a significantly higher concentration of components which eluted in the polycyclic aromatic hydrocarbon (PAH) chemical class fraction. Amino-substituted PAH were present in both nonhydrogenated coal liquid and creosote materials. The creosote and SRC-II FOB crudes and nitrogen-containing polycyclic aromatic compound (NPAC) chemical class fractions expressed similar microbial mutagenicity. Based on chemical analysis data, the predicted tumorigenic potency of the creosote in laboratory bioassay systems would be equivalent to or greater than the SRC-II FOB.

Zusätzliches Material: 2 Ill.