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R L Karlsen

Publications and source records attributed to R L Karlsen.

34 records · Page 2Linked to original sources
PubMed1980

[Pupillography].

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Humans↗
PubMed1980

Electron microscopy of lanthanum in plasma.

Aqueous solutions of lanthanum nitrate may be used as electron microscopic tracers in vivo to study vascular permeability in the experimental animal. However, with this technique the size of the tracer articles is not known. To gain information about the tracer size, we injected lanthanum nitrate into the blood circulation of living rabbits. The plasma obtained from such animals 30 min later, was studied with the electron microscope. The plasma contained an electron-dense material, readily visible in the electron microscope. A precipitate obtained after centrifugation of the whole blood to separate the cells, also contained the tracer. Lanthanum was found in large amounts in the fibrin clot obtained after treating the plasma with thrombin. The tracer was not detected in the "serum" (i.e. thrombin-treated plasma). The study indicates that ionic lanthanum injected into the blood circulation of living rabbits, is to a great extent bound to fibrinogen, and that the smallest possible size of the tracer is that of the fibrinogen molecule (m.w. 330,000). Larger particles are present as well.

Animals↗
PubMed1980

Correlations between acetylcholinesterase activity in guinea-pig iris and pupillary function: a biochemical and pupillographic study.

Acetylcholinesterase (AChE) in guinea pig iris was inhibited by methylisocyclopentylfluorophosphate (soman) administered topically or parenterally, and enzyme activity was correlated to pupillary diameter by infrared pupillography. After a single topical soman instillation into the conjunctival sac there was an almost linear relationship between the reduction in AChE activity and pupillary diameter. Topical administration of soman at 24-h intervals in doses capable of almost complete inhibition of AChE in iris was accompanied by a reduced miotic effect of this drug. This was indicated by a reduced rate of the soman-induced pupillary constriction, a less pronounced reduction in pupillary diameter, and a more rapid return of the pupillary diameter to normal size. The change in pupillary diameter occurred after three daily administrations and remained constant during 31 days of treatment. These observations were seen irrespective of inhibition of blood AChE. The decrease in response to repeated administration could not be explained by a reduced inhibitory effect of soman on AChE, by a more rapid de novo synthesis of AChE, or by a change in the number of the muscarinic receptors as determined by quinuclidinyl benzilate binding. When soman or DFP was administered subcutaneously in high doses a severe AChE inhibition was obtained in iris without any concomitant miosis.

Acetylcholinesterase↗
PubMed1979

Changes in pupillary dynamics in young men during prolonged severe exercise.

Infrared pupillography has been performed on 9 male cadets taking part in a combat course lasting for 5 days. The combat course involved lack of sleep, strong physical exercise and caloric deficit. During the course pupillary size was determined after rapid adaptation to darkness and the rate of concentration and the rate of dilatation after stimulation of the opposite eye with light was determined. Dilatation time increased by 50% towards the end of the course and pupillary size before light stimulation was reduced by 14%. On day 3 and 5, but not on day 1, small amplitude pupillary oscillations were observed. The speed of contraction was, however, unchanged.

Adult↗
PubMed1978

Evidence for glutamate as a neurotransmitter in the corticofugal fibres to the dorsal lateral geniculate body and the superior colliculus in rats.

The high-affinity uptake of L-glutamate, D-aspartate and GABA were examined in homogenates from the dorsal lateral geniculate body and the superior colliculus after removal of the right visual cortex of adult rats. The high-affinity uptake of D-aspartate and L-glutamate were reduced by 53 to 75% respectively in the dorsal lateral geniculate body and by 46 and 53% respectively in the superior colliculus ipsilateral to the lesion. The uptake on the contralateral side was unaffected. The reductions were detected 3 days after the lesion and were maximally developed after 7 days. Subcellular fractionation showed that the main part of the uptake was confined to the synaptosomal fraction of both regions and that the reductions were most prominent in this fraction. The lesion was not accompanied by significant changes in high-affinity uptake of GABA nor in changes of choline acetyltransferase and glutamate decarboxylase activities. The high-affinity L-glutamate uptake on the contralateral visual cortex was unchanged from control values. After ablation of the visual cortex the level of L-glutamate was reduced by 32 and 17% in the ipsilateral dorsal lateral geniculate body and superior colliculus, respectively. The levels of the other amino acids examined, including L-aspartate, were unchanged. Enucleation had no effect on the uptake of L-glutamate and of GABA in the dorsal lateral geniculate body or in the superior colliculus.

Animals↗
PubMedDate not supplied

Pholcodine interference in the immunoassay for opiates in urine.

The excretion in urine after single oral therapeutic doses of morphine derivatives was analysed with radioimmunoassay (RIA) and homogeneous enzyme immunoassay (EMIT) for opiates. In contrast to the rapid excretion of ethylmorphine and codeine, pholcodine showed positive results for opiates 2-6 weeks after intake when the urines were analysed with the RIA-method. When analysed with the EMIT-method, positive results were obtained for pholcodine for approximately 10 days. As pholcodine is a common component in cough mixtures, its prolonged excretion could represent a hazard in interpreting the results from drug analyses of urines.

Antitussive Agents↗