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Biomedical subjects

J de Bruijne

Publications and source records attributed to J de Bruijne.

5 recordsLinked to original sources
PubMed1994

Hyperlipoproteinaemia associated with atherosclerosis and cutaneous xanthomatosis in a cat.

Bilateral uveitis and multiple xanthomas (fat deposits in the skin) are described in a 3.5-year-old ovariohysterectomized female Persian cat. The cat had been treated for 2 years with corticosteroids. Examinations included a routine blood chemistry profile, radiographic examination of the thorax and abdomen, histopathological examination of multiple skin punch biopsies, and analysis of blood lipid components by cellulose-acetate electrophoresis and by preparative ultracentrifugation studies. Total lipid values were 23 g/l. Ultracentrifugation studies indicated strongly elevated VLDL and LDL fractions and a decreased concentration of the HDL fraction. Because of sudden blindness the cat was euthanized at the request of the owner. Autopsy revealed massive atherosclerotic changes in the large abdominal vessels, the wall of the aorta, and the coronary vessels. Although the exact pathogenesis remains uncertain, these unusual findings might be explained by a primary hyperlipoproteinaemia, complicated by long-term use of corticosteroids.

Animals↗
PubMed1983

The establishment of regular beating in populations of pacemaker heart cells. A study with tissue-cultured rat heart cells.

Single isolated neonatal rat heart cells beat slowly (mean beating interval duration in the range of seconds) and irregularly (coefficient of variation greater than 40%). It is shown that slowness and irregularity of beating are intrinsic properties of the cells and are not caused by dissociation damage or lack of conditioning factors in the culture medium. When cell contacts are established either by letting the cultures grow for given amounts of time or by plating cells at increasing densities both interval duration and irregularity decrease. The beating regularity of small groups of interconnected cells (3 to 35 cells) and larger groups (200 to 15000 cells) is comparable. There is no clear cut proportionality between number of interconnected cells and beating regularity. Confluent monolayers beat fast (mean interval duration ranging between 200 and 400 ms and regular (coefficient of variation less than 5%). The hypothesis is discussed that this clock-like behavior of monolayers of heart cells is caused by the interaction of several pacemaker centers which are by themselves less regular and beat more slowly.

Action Potentials↗
PubMed1980

Membrane properties of aggregate of collagenase-dissociated rat heart cells.

Aggregates of collagenase-dissociated neonatal rat heart cells have been tested for several membrane properties and shown to be comparable with cells from the intact heart. Action potentials, recorded from driven aggregates, are fully suppressed by tetrodotoxin (TTX). Under Mn2+, the plateau phase of the action potential disappears and no more mechanical activity can be detected. In aggregates, therefore, apparently both the fast sodium inward current and a slow inward current, which is at least partly carried by Ca2+ ions, contribute to the action potential. Pacemaker activity in spontaneously active aggregates is enhanced by adrenaline and slowed down by acetylcholine. Adrenaline also increases the plateau phase amplitude of the action potential and thereby the rate of repolarization. Acetylcholine shortens the action potential duration and increases the resting membrane potential. The electrical coupling between the cells in the aggregates is so tight that the aggregate seems to behave passively, like a single cell. It is concluded that aggregates of collagenase-dissociated neonatal rat heart cells may be used to study active electrical properties using the voltage clamp technique.

Acetylcholine↗