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Biomedical subjects

U T Brunk

Publications and source records attributed to U T Brunk.

At least 91 records · Page 5Linked to original sources
PubMed1989

Superoxide anion radical production in different animal species.

The general objective of this study was to examine the relationship between oxygen free radicals and the aging process. The rate of superoxide anion radical (O2.-) generation was measured in liver sub-mitochondrial particles from mouse, rat, rabbit, pig and cow, and in flight muscle sub-mitochondrial particles from the housefly. The rate of O2.- generation was determined as superoxide dismutase inhibitable reduction of ferricytochrome c in the presence of antimycin A and KCN. O2.- generation was inversely related to maximum species life span potential (MLSP) (r = -0.92). A 24-fold difference in the rate of O2.- production was observed between the cow and the fly while a 6-fold difference existed among the mammals. The results are interpreted to indicate that under identical conditions, mitochondria from organisms with low MLSP have a relatively greater propensity to generate O2.-. This may be suggestive of innate differences in the molecular organization of the inner mitochondrial membrane among different species.

Animals↗
PubMed1989

Effect of ethanol on lipofuscin accumulation in cultured rat cardiac myocytes.

The objective of this study was to determine the effect of ethanol on in vitro life span, rate of contraction and lipofuscin content of neonatal rat cardiac myocytes. Lipofuscin was quantified by microspectrofluorometry. The effects of 0, 3.1, 6.5, and 12.5 mM ethanol on myocytes, kept under an ambient oxygen concentration of 20% and 40%, were studied. Exposure to low concentrations of ethanol resulted in a decrease in the amount of lipofuscin whereas exposure to high concentration of ethanol caused an increase in the level of lipofuscin. The length of cell survival in controls and 3.1 mM ethanol exposed myocytes was similar under 20% oxygen, but was longer in the latter group under 40% oxygen, as compared to controls. The total number of contractions in 3.1 mM ethanol-exposed myocytes were, respectively, 4% and 8% higher under 20% and 40% oxygen atmosphere than in control cells.

Age Factors↗
PubMed1989

Effect of ambient oxygen concentration on lipofuscin accumulation in cultured rat heart myocytes--a novel in vitro model of lipofuscinogenesis.

The objective of this study was to elucidate the factors involved in the accumulation of lipofuscin in post-mitotic cells. The hypothesis that oxidative stress accelerates the rate of lipofuscin accumulation was tested by examining the effects of 5%, 20%, and 40% ambient oxygen concentration on lipofuscin content in cultured rat cardiac myocytes. Lipofuscin was quantified by microspectrofluorometry at 7 and 12 days of in vitro age. Lipofuscin-emitted yellow autofluorescence increased in direct relationship to ambient oxygen concentration with age. Transmission electron microscopic examination of the cells after 3, 8, and 12 days in culture indicated a progressive time and oxygen dependent increase in the frequency and size of lipofuscin organelles. The results are interpreted to suggest that oxidative stress is one of the causal factors in the accumulation of lipofuscin.

Animals↗
PubMed1988

Effect of ferric iron and desferrioxamine on lipofuscin accumulation in cultured rat heart myocytes.

The general objective of this study was to examine the role of oxidative stress and transition metal catalysis in lipofuscinogenesis in postmitotic cells. Effects of 30 microM ferric chloride and different concentrations of desferrioxamine, ranging from 12.5 to 50 microM, on lipofuscin content were examined in rat cardiac myocytes at 6 and 12 days of in vitro age, under 20% and 40% ambient oxygen concentration. Lipofuscin was quantified by microspectrofluorometry of individual cells. Using X-ray microanalysis, iron was found to be sequestered in the secondary lysosomes that also contain the fluorescent lipofuscin material. Augmentation of iron in the culture medium markedly increased the level of lipofuscin accumulation while desferrioxamine had the opposite effect. Both of these effects were more pronounced at higher oxygen tension. Iron and oxygen had a cumulative effect on lipofuscin accumulation. Results are interpreted to indicate that oxidative stress and iron, in loosely bound form, are causal factors in lipofuscinogenesis. The possibility of employing microspectrofluorometry of lipofuscin as an indicator of oxidative stress is emphasized.

Cells, Cultured↗
PubMed1986

Translocation of human glial and glioma cells in culture.

Two normal glial lines and four selected malignant glioma lines--considered as representative of the varying morphologies previously found among these lines--were studied quantitatively as to their translocatory ability on glass under standard culture conditions. The two glial lines showed very similar characteristics with almost identical results for total and net translocation, as well as in their directional persistence. The glioma lines gave values for these criteria which were either greater or lower than those of the glial cells. These values could to a certain degree be related to phenotypic traits, such as degree of cell polarization and amounts of cytoplasmic microfilament bundles. The findings once again display the heterogeneity of the human malignant glioma lines and raise doubts as to the general applicability of findings in studies of single lines of tumor cells, or of experimentally transformed cells, to all malignant cells.

Cell Movement↗
PubMed1984

Influence of oxygen tension, pro-oxidants and antioxidants on the formation of lipid peroxidation products (lipofuscin) in individual cultivated human glial cells.

Cultivated human glial cells, kept in a state of density-dependent inhibition of growth, accumulate age pigment (lipofuscin) within their lysosomal vacuomes which has the same characteristics as the age pigment observed in vivo. The rate of formation and accumulation of lipofuscin is greatly accelerated under the conditions of routine cell culture in comparison to the in vivo event. Lipofuscin is generally considered to be composed of products of lipid peroxidation and thus it would be reasonable to suggest that factors which influence lipid peroxidation would also alter the rate of lipofuscin formation and accumulation. Human glial cells were grown in the presence of various oxygen concentrations (5%, 10%, 20%, 40%) or exposed to pro-oxidants (vitamin C/Fe) or antioxidants (vitamin E/Se, dimethylsulfoxide, reduced glutathione) treatments in the presence of normal oxygen concentration (20%). It was found that these factors can modulate (accelerate or decrease) the rate of formation of lipofuscin. This study thus provides: (1) important supportive evidence for the lipid peroxidation origin of lipofuscin, (2) a useful model system for studying the effect of lipofuscin accumulation on lysosomal function and cell growth kinetics, (3) evidence that our culture conditions are far from ideal: oxygen concentration may drastically alter rates of lipofuscin formation and accumulation. Cell culture technique, as we know it today, may benefit from more closely controlled oxygen tensions, i.e. by reducing oxygen to levels that more closely approximate conditions in vivo.

Antioxidants↗
PubMed1984

Fine structural studies on cultured human glial and glioma cells: techniques and applications.

Transmission electron microscopy (TEM), scanning TEM, and scanning electron microscopy in combination with special culture techniques and ordinary cell biologic methods were used to study several problems in cellular pathology and tumor biology. The human glial and glioma cell system is also discussed. The cell system and ultrastructural techniques described may be used in many other areas of study and may be relevant in future investigations of cell pathology.

Cell Survival↗
PubMed1983

An approach to the assessment of membrane stability of cultured cells.

A simple method for assessing the combined stability of the plasma and lysosomal membranes of cultured cells is described. Monolayers of normal, human glial cells were incubated in situ in an isotonic, buffered sucrose solution (pH 5.0) containing the acid phosphatase (AP) enzyme substrate p-nitrophenyl phosphate (PNPP). The rate of appearance, in the solution, of the reaction product p-nitrophenol (PNP) was measured spectrophotometrically, curves then plotted, and fitted by computer. "Lag time" (LT) was calculated, and an index of membrane lability constructed, termed "fragility index" (FI). Transmission electron microscopy (TEM), "vital" staining of the cells with fluorescein diacetate (FDA) and Evans Blue (EB), and use of a Gomori-type cytochemical technique, indicate that the data reflects the combined stability of lysosomal and plasma membranes. The latter playing the more critical role. Cell cultures pre-incubated with various membrane labilizing or stabilizing agents were compared. Control, 0.3 M sucrose, and normal saline treated cells demonstrated similar stability. Distilled water decreased AP latency (increased fragility), and the magnitude of this effect was time dependent. Cells fixed in glutaraldehyde (GA) retained much of their osmotic reactivity, as confirmed by distilled water treatment. Oxygen derived free radicals caused pronounced fragility, while dexamethasone, a membrane stabilizing agent, decreased membrane fragility. Triton X-100 abolished latency completely, and total AP activity was very rapidly recovered outside the cells in the surrounding incubation medium. These results suggest this technique yields a measure of membrane stability which is sensitive enough to differentiate between known stabilizers and labilizers of membranes. Hence, this may prove an easy and useful aid for the assessment of how various substances and environments modulate the lysosomal and plasma membrane stability of cultured cells.

Acid Phosphatase↗
PubMed1982

Growth and morphological characteristics of two brain metastases of human large cell carcinomas of the lung in vivo and in monolayer and spheroid cultures.

The morphology and the proliferation rate of two metastases to the brain of human large cell cancer of the lung were determined following excision. TEM of the metastasis suggested one to be a low differentiated squamous cell carcinoma, while the other fullfilled the criteria for an adenocarcinoma. Cell cultures derived from these metastases were studied as to their morphology and proliferative capacity when grown as monolayers and in spheroid culture. One of the cell lines obtained (Tp 242-C) was found to be anaplastic in culture and to show few special characteristics, while the other (Tp 362-C) demonstrated a number of unique qualities such as an inability to translocate both on glass and on substrate covered by extracellular matrix, an island pattern of cell growth in monolayer culture, multiple desmosome junctions between the cells, and the production of inter- and intra-cellular, villi- covered luminae. In spheroid culture the line Tp 242-C formed tissue-like tumorlets which of the original metastasis. These two new lines of human lung cancers, when fully characterized, may prove of value in biological and therapeutic studies of human lung cancer of the large cell type, the origin, homogeneity as a group and behaviour of which are still under debate.

Aged↗
PubMed1981

TEM and SEM findings in cat fibroblasts cultivated in vitro with and without Mycoplasma.

Mycoplasma contamination of cultured cells may cause considerable interference with their behaviour and metabolism. Whether or not mycoplasma are actually taken up by cells in vitro has long been a matter of dispute. In the present study mycoplasma were shown to phagocytosed by feline lung fibroblasts and to end up in the lysosomal vacuome of the cells, where the organisms were only partially degraded by the hydrolytic enzymes leading to a rapid (within a few days) accumulation of secondary lysosomes of the residual body variety. It is thus obvious that studies on the structure and function of the lysosomal vacuome in cultured cells are possible only if precautions are taken to avoid that the cultures become contaminated by mycoplasma.

Animals↗
PubMed1980

Cytoplasmic effects of X-irradiation on cultured cells in a non-dividing stage. 4. Studies of sparsely grown, serum-deprived cells.

Cultured human glial cells were blocked in interphase (G1) by 24 h of serum starvation and subsequently subjected to 200 Gy, 8 MV X-radiation. Immediately following irradiation the cultures were transferred to serum-containig medium. Time-lapse cinemicrography performed during the next 48 h showed a profoundly disturbed motility with decreased ability for polarization and locomotion of the irradiated cells. Specimens fixed 24 and 48 h after irradiation and investigated by immunofluorescence with tubulin-antibodies and DNase/DNase-antibodies, and by whole cell transmission electron microscopy showed derangements in the distribution of microfilament bundles related to the cytoplasmic ramification of the irradiated cells, but otherwise no detectable alterations in structure or distribution of either microtubules or microfilaments. It is suggested that the alteration in the arrangement of filament bundles is of importance to the impaired locomotion of the irradiated cells.

Cell Movement↗
PubMed1979

Ultrastructural features of cultured human glia and glioma cells.

The fine structure of three lines of human normal glial cells and eight established lines of malignant glioma cells are described. The glial cell lines were ultrastructurally very similar whereas the glioma cell lines differed greatly from one another. In sparse proliferating cultures there were no consistent findings which distinguished the glioma cell lines as a group from the normal glial cells. Only in post-confluent cultures could the consistently irregular cell surfaces and ruffling, both at the cell periphery and centrally on the upper cell surface, with associated pinocytosis, distinguish the glioma from the post-confluent glial cultures, which did not possess these properties. The common attributes of post-confluent glioma cells reflect the cells' continued proliferation. The glioma lines did display individual ultrastructural characteristics which appear to be stable, the glioma lines having retained these during a number of years of continual passage.

Cell Division↗
PubMed1979

The fine structure of growing human glia and glioma cells. Whole cell preparations.

Three lines of normal human glia cells and eight established lines of malignant glioma cells have been studied in the electron microscope (E.M.), using preparations of critical-point dried whole cells, sparsely grown on formvar-coated, E. M., gold grids. The malignant cell lines showed a very varied morphology, almost every line having its peculiarities as compared to the essentially identical normal glia lines. The major differences noted concerned the form of the leading lamellae, number of microspikes and the distribution of organelles such as secondary lysosomes and mitochondria. No single consistent finding made it possible to differentiate the glioma cells as a group from the glia cells in sparse cultures. The findings of this study show some of the individual glioma cell lines to have characteristic cell-surface structures. They were found to be identical with the findings in previous SEM studies, suggesting the peculiarities of the individual malignant glioma lines to be stable and retained, despite continual passage.

Cell Division↗