Biomedical subjects

W Bondareff

Publications and source records attributed to W Bondareff.

At least 55 records · Page 3Linked to original sources

PubMed1975

Developmental morphology of the subarachnoid space and contiguous structures in the mouse.

Development of pia-arachnoidal membranes in the mouse occurs in four stages: the first (prenatal days 10-13) follows closure of the neural tube and is a period of initial vascularization of the developing telencephalon; the second (prenatal days 14-16) is a period of delineation during which the limits of the subarachnoid space are defined; the third (prenatal day 17 to birth) is a period of ensheathment of pia-arachnoidal blood vessels; and the fourth (birth to postnatal day 21) includes addition of smooth muscle to larger vessels, the appearance of macrophages in the subarachnoid space, and a general increase in extracellular collagenous and elastic fibers. The mesenchyme over the telencephalic surface in the 10-day fetus has a typically large extracellular space. By the 13th fetal day cerebrospinal fluid begins to seep into and replace it. The mesenchymal extracellular compartment is reduced peripherally, resulting in a compacted pia-arachnoidal tissue which limits the peripheral extent of the subarachnoid space. By the 21st postnatal day a subarachnoid space typical of the adult animal has been established.

Animals↗

PubMed1975

Cortical cytoplasm and configurational changes of RGC-6 cells exposed to cytochalasin B.

RGC-6 cells, grown to confluency in monolayer cultures, are typically fusiform. In sections of these cells, fixed in situ and examined in the electron microscope, a discontinuous zone of cortical cytoplasm (5-4 nm wide), was found subjacent to the plasma membrane of the free surface. It was composed largely of 5-7 nm microfilaments distributed in an apparently irregular network and appeared to comprise a discrete zone separating the plasma membrane from the underlying endoplasm. Following incubation with cytodhalasin B (5 mug/ml), the configuration of the cells changed markedly. The perikaryal cytoplasm appeared to swell, while the cellular processes became attenuated and often terminated in flower-like tips. Although more discontinuous and somewhat less dense, the fine structure of the cortical cytoplasm appeared little affected by incubation with cytochalasin B for one hour. By 48 hours no zone of cortical cytoplasm was found. Subplasmalemmal microfilaments were no longer identifiable and endoplasmic organelles were found in direct contact with the plasma membrane of the free surface, which appeared to have collapsed onto the underlying endoplasm. The change in cell configuration resulting from exposure to cytochalasin B occurred at 37 degrees C but not at 4 degrees C, suggesting a dependency on metabolic activity. It did not, however, appeared related directly to protein synthesis. Whereas incorporation of 3H-leucine was decreased to 46.9% and 62.9% of control values after one hour or two hours exposure to cytochalasin B, respectively, no change was found after 24 or 48 hours. It is suggested that the effect of cytochalasin B on cell form, which appeared not to be a direct effect on either protein synthesis or subplasmalemmal microfilaments, may represent a primary response of the cortical cytoplasmic matrix.

Animals↗

PubMed1975

A smooth muscle plexus associated with the aqueous outflow pathway of the rabbit eye.

Smooth muscle cells were demonstrated adjacent to the aqueous outflow pathway in rabbit eyes. The cells were arranged as a discontinuous band, one to three layers thick and extended from the termination of Descemet's membrane to the ciliary body. Most of the cells were oriented with their long axes at right angles to the aqueous plexus, but many were arranged in a direction parallel to the plexus. The organization of the cells suggests that their contraction would exert a bi-directional force, and therefore, affect aqueous outflow resistance.

Animals↗

PubMed1974

Biogenic amines in cultured neuroblastoma and astrocytoma cells.

The presence of biogenic amines in cultured cells of mouse neuroblastoma C-1300 (clone NB-2a) was suggested by fluorescence-microscope histochemistry. Incubation in media containing L-[(14)C]tyrosine and L-[(14)C]tryptophan for 24 h, followed by high-voltage electrophoresis, radiochromatogram scanning, and scintillation counting, confirmed the presence of [(14)C]dopamine, [(14)C]norepinephrine, [(14)C]epinephrine, [(14)C]serotonin, [(14)C]tyramine, and [(14)C]octopamine. Dopamine, norepinephrine, epinephrine, and serotonin were demonstrated spectrophotofluorometrically in concentrations, expressed as micrograms amine per milligram protein, of 1.19, 0.027, 0.038, and 0.148, respectively, for cells in a stationary growth phase. Fluorescence-microscope histochemistry also suggested the presence of biogenic amines in cultured astrocytoma cells (cell line C6). Spectrophotofluorometric assay of cells in a stationary growth phase demonstrated intracellular dopamine, norepinephrine, epinephrine, and serotonin in concentrations significantly lower than those of neuroblastoma cells.

Animals↗

PubMed1973