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Biomedical subjects

P Kucera

Publications and source records attributed to P Kucera.

At least 91 records · Page 5Linked to original sources
PubMed1985

Fibronectin in the area opaca of the young chick embryo. Immunofluorescence and immuno-electron-microscopic study.

Distribution of fibronectin-like immunoreactivity was studied in the area opaca of the young chick embryo (stages 4-6 HH) by use of the immunofluorescence and protein A-coupled to colloidal gold techniques. Fibronectin, associated to the basement membrane, formed a fibrillar network, the pattern of which changed from the centre to the periphery of the area opaca. At the ultrastructural level, differences in fibronectin distribution were found between non-moving and moving cells. The epithelial-like cells presented fibronectin staining exclusively on their basal side. Actively migrating cells (edge and mesodermal cells) showed immunoreactive material localized around their entire surface and within the cytoplasm. The fibronectin distribution is discussed in relation to three important phenomena taking place during the early growth of the area opaca: anchorage and migration of the edge cells, modification of cell shape in relation to mechanical tension, and expansion of the area vasculosa.

Animals↗
PubMed1985

Pathways of the early propagation of virulent and avirulent rabies strains from the eye to the brain.

Penetration of the central nervous system of the adult rat by the CVS strain of rabies virus and its two avirulent derivatives Av01 and Av02 has been studied by inoculation of the virus into the anterior chamber of the eye. The primary sites of penetration of CVS were (i) the intraocular parasympathetic oculomotor fibers, (ii) the retinopetal fibers of pretectal origin, and (iii) the intraocular fibers of the ophthalmic nerve. The mutant strains, however, lost the capacity to invade the two former groups of fibers, although their penetration into the trigeminal system was not impaired. Neither strain CVS nor the mutants infected primarily the intraocular adrenergic terminals and the optic nerve. Mutant strains, but not CVS, were able to infect the lens. These results indicate that the cholinergic receptor may not be the only receptor for rabies virus and that rabies virus is conveyed in the nervous system by retrograde axoplasmic flow. Strain CVS spread throughout the brain and propagated eventually back to the retina. The mutants penetrated the brain as well, but the infection was slow, involved different cerebral structures, and cleared up completely in 3 weeks, probably because of an efficient immune response.

Animals↗
PubMed1984

Oxygen consumption in collagenase-liberated rat adipocytes in relation to cell size and age.

Oxygen consumption of collagenase-liberated rat adipocytes was measured by two different techniques: a microspectrophotometric method using hemoglobin as indicator of respiration and a technique using the oxygen electrode. These two completely different techniques gave similar values for oxygen consumption. With the spectrophotometric method, the oxygen consumption of single fat cells was determined. A close positive correlation (r = greater than 0.90) between oxygen consumption and fat cell size was observed in each tissue examined. With the oxygen electrode technique, oxygen consumption of adipocyte suspensions from young (40 days, 180 g) and old (90 days, 480 g) rats was examined. Fat cells of the suspensions were separated into classes of different size by a flotation technique. A significant positive correlation between fat cell size and oxygen consumption was observed in both young (r = 0.88) and old (r = 0.95) rats. However, the slope was much steeper in young rats. At a cell weight of 0.1 microgram the oxygen consumption was 0.364 and 0.086 microL O2/10(6) cells/min-1 in young and old rats, respectively. In the literature, a number of separate metabolic pathways have been found to be related positively to fat cell size and negatively to age. We conclude that these scattered metabolic observations are in agreement with integrated data on energy expenditure as evaluated from oxygen consumption. Estimations of the energy expenditure of adipose tissue indicates that this tissue is responsible for about 1% and 0.5% of the total energy expenditure in young and old rats, respectively.

Adipose Tissue↗
PubMed1982

[Progression of the rabies virus in the visual system of the rat].

The CVS rabies virus, inoculated in the anterior chamber of the eye, is transported from the retina to the central nervous system only along the accessory optic tract and invades transsynaptically its terminal nuclei. On the other hand the retino-geniculo-cortical system is affected much later. Thus the virus shows a special affinity for a well defined neuronal system and behaves as a precise tracer of its intracerebral connections.

Animals↗
PubMed1982

In situ recording of the mechanical behaviour of cells in the chick embryo.

The changes of viscosity in different regions of the intact living early chick embryo were recorded by a new sensitive and non-invasive technique. In the heart, the very first yet invisible mechanical activity has been clearly detected and its further differentiation followed. In other regions, especially in the Hensen's node, spontaneous slow and oscillating mechanical activity has been observed. It has been shown that the undifferentiated embryonic tissue can as well respond to electrical, mechanical or chemical stimulations. The recorded changes have been interpreted as manifestations of the cell mechanical work i.e. active tension, cell shaping or movement. The technique represents a new tool for physiological and pharmacological studies of the undifferentiated embryonic cells and the early morphogenetic phenomena.

Animals↗
PubMed1980

Spatio-temporal micromeasurements of the oxygen uptake in the developing chick embryo.

A method has been developed for the determination of the oxygen uptake of small areas (0.01 mm2) in an entire chick embryo cultured in vitro under defined metabolic conditions. It is based on the recordings of the spectral changes of the hemoglobin used as oxygen source for the respiring tissue (Barzu and Borza, 1967). Rapid scanning of the hemoglobin absorbance over the preparation allows a comparison of the O2 uptake of various regions. Values of the order of 10(-2) 1 O2 . min-2 are measured in less than 10 sec with a spatial resolution of 100 micron. The differentiation of embryonic tissue is not disturbed by the measurements. The O2 diffusion in the media and in the tissue has been analyzed by digital simulation. The O2 uptake of the Hensen's node was measured from embryos starting at the stage of definitive primitive streak (stage 4) up to the stage of 10 somites. It increases from 0.6 to 1.1 nl . h-1 with a marked acceleration between stages 4 and 5. The values corrected for the protein content of the Hensen's node at stage 4, 5, 6 and 8 are 32, 30 and 28 microliter . mg-1 . h-1 respectively. The first scanning results show different patterns of the O2 utake at the level of the Hensen's node and of the neural plate. At stage 6-7, the corrected O2 uptake is 30 microliter . mg-1 . h-1 for . the former and 43 microliter . mg-1 . h-1 for the latter.

Animals↗
PubMed1980

Nasojejunal feedings in infants with increased intracranial pressure.

A relatively common complication in preterm infants is intracranial hemorrhage, which is often followed by increased intracranial pressure and hydrocephalus. Shunt procedures must often be delayed because CSF protein and RBCs are increased. Since vomiting often precludes gasric feeding of these infants, we attempted nasojejunal feedings while awaiting the optimal time for shunt insertion. Favorable results were obtained in three infants in whom nasojejunal feedings were utilized.

Cerebral Hemorrhage↗
PubMed1979

Use of microbore columns for the separation of substances of biological origin.

A gradient system for use with microbore columns is described and the repeatability of the system determined. A simple sampling device for use with aqueous biological samples is described, and the advantages of the high mass sensitivity of microbore columns for the analysis of such samples are discussed. The sensitivity of the system is demonstrated by the determination of acetophenone in water at a level of one part per billion. The use of the apparatus for the separation of low-molecular-weight, non-ionic compounds contained in blood is also demonstrated. It is shown that excellent separations of such components can be obtained from as little as 400 microliter of serum.

Blood Chemical Analysis↗