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Specific effects of the benzodiazepine midazolam on visual receptive fields in light and dark adapted human subjects (1992)

Groner, M. ; Fisch, H. -U. ; Walder, F. ; [et al.]

Springer

Psychopharmacology 109 (1992), S. 68-76

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ISSN: 1432-2072

Keywords: Visual system ; Visual receptive fields ; Subthreshold summation ; Shift effect ; Dark adaptation ; Benzodiazepines ; GABA ; Bicuculline ; Dopamine ; Levodopa ; Sulpiride ; Atropine ; Human ; Cat ; Psychophysics

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Abstract Psychophysical experiments in humans have revealed similar characteristics of visual receptive fields as were found in cats and monkeys from retinal ganglion cell recordings. In addition, in some retinal ganglion cells of cats the GABA antagonist bicuculline decreases the activity of the inhibitory surround. These findings led to two predicitions: 1) benzodiazepines will selectively increase the inhibitory surround of human visual receptive fields, 2) after dark adaptation, no free GABA will be available in the synapses and benzodiazepines will have no effect on the visual system. Characteristics of human receptive fields were determined by subthreshold summation: the contrast threshold of a vertical line was measured dependent on the distance of two parallel flanking lines whose contrast was below threshold. Both hypotheses were confirmed: the threshold in the inhibitory region of receptive fields was specifically increased in a dose-dependent manner by midazolam PO (7.5 mg:P〈0.05; 15 mg:P〈0.01). In dark-adapted subjects no effect of midazolam was found. Control experiments with atropine (1 mg IV), sulpiride (100 mg IM), and levodopa (100 mg PO) showed no specific effect. The visual system may be a model to bridge the gap between animal and human psychopharmacology.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02245482

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Molecular orbital analysis of the XPS spectrum of a fluorine containing polyimide: PMDA-BDAF (1988)

Silverman, B. D. ; Sanda, P. N. ; Clabes, J. G. ; [et al.]

Bognor Regis [u.a.] : Wiley-Blackwell

Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 1199-1205

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ISSN: 0887-624X

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The results of XPS measurements and molecular orbital calculations performed on the fluorine containing polyimide, PMDA-BDAF, are presented. The calculated carbon 1s (C1s) core energy level positions are compared with the level positions inferred from the XPS measurements. Within Koopman's approximation, the observed shape of the main XPS peak is consistent with the calculated distribution of C1s levels under this peak. Comparison of the magnitude of the carbonyl XPS peak intensity with the main peak intensity indicates a carbonyl C1s signal deficiency compared with that expected for “ideal bulk stoichiometry” i.e., for a polymer with no crosslinks or chain terminations. Comparison of data obtained from a grazing emission (surface sensitive) geometry with that obtained from a normal emission geometry, which probes more deeply into the bulk, indicates a signal enhancement of the C1s levels associated with carbon atoms of the CF3 groups as one nears the polymer surface. Such enhancement might be due to either actual differences in chemical composition, or to preferential structural ordering near the polymer surface.

Additional Material: 3 Ill.