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At least 73 records · Page 4Linked to original sources
PubMed1961

Spheroplasts of the yeast Candida utilis.

Svihla, G. (Argonne National Laboratory, Argonne, Ill.), F. Schlenk, and J. L. Dainko. Spheroplasts of the yeast Candida utilis. J. Bacteriol. 82:808-814. 1961.-The formation and properties of spheroplasts of the yeast Candida utilis, produced by digestion of the cell walls with snail gut juice (Helix pomatia) in isotonic medium, were studied by phase, interference, and ultraviolet microscopy, and tracer techniques. Cells cultivated in the presence of l-methionine, S-methyl-l-methionine, and l-homocysteine (5 mumoles/ml) were more susceptible to enzyme action than ordinary cells. These cells contain increased amounts of S-adenosylmethionine in the vacuole which facilitates ultraviolet microscopy. Spheroplasts are stable in 0.6 m KCl containing 0.04 m phosphate, but are disintegrated by water, sonic vibration, or ultraviolet irradiation. Exposure in isotonic medium to 6 x 10(4) erg/mm(2) energy at 253 mmu breaks the cytoplasmic membrane and liberates the vacuole with membrane intact. The vacuolar membrane may be broken with about three times the initial dose of ultraviolet.

Candida↗
PubMed1988

Rigidity of the nucleus during nuclear rotation in 3T3 cells.

Using near infrared microscopy and ultraviolet fluorescence microscopy of living 3T3 cells stained with the fluorochrome Hoechst 33342, we have demonstrated that the nucleoli and Hoechst 33342-stained chromocenters in the nucleus maintain a fixed pattern during nuclear rotation. We conclude that the term "nuclear rotation" refers to rotation of the entire nucleus in the cytoplasm of interphase cells, and that nuclear rotation is not an expression of karyoplasmic streaming. In conjunction with earlier results on nuclear rotation the data imply that the interface of nuclear rotation is located either between the two nuclear membranes or in the adjacent cytoplasm.

Benzimidazoles↗
PubMed1996

Perimetric [Ca2+]i rise and exocytosis detected by ultraviolet laser scanning confocal microscopy in rat peritoneal mast cells.

It has been reported that in dialysed mast cells an increase in mean [Ca2+]i is neither necessary nor sufficient for secretion; however, it is possible that juxtamembranal [Ca2+]i may exceed the mean [Ca2+]i before exocytosis. The present study was carried out to analyse spatial and temporal dynamics of [Ca2+]i and concomitant exocytosis in intact rat peritoneal mast cells using UV laser scanning confocal microscopy. Stimulation with Compound 48/80 (16 microM) increased mean [Ca2+]i, causing an initial rapid elevation from 40 to 200 nM, which lasted for 6 s and was followed by a delayed secondary increase to 600 nM. Exocytotic images were seen in the cell perimeter 16 s after the stimulation. Perimetric and nuclear [Ca2+]i increased to several mumoles per litre, while that in the intermediate region remained low. In a Ca(2+)-deficient environment, Compound 48/80 still increased perimetric [Ca2+]i to micromolar values and induced exocytosis. This study clearly indicates, for the first time, that a perimetric increase in [Ca2+]i to micromolar levels precedes exocytosis, in intact, as opposed to permeabilized cells.

Animals↗
PubMed1979

A quantitative histologic study of tissue responses to ramal sagittal splitting procedures.

The viability of bone after sagittal splitting of the mandibular ramus by two techniques was studied. Decalcified sections of bone were studied with light microscopy; ground sections of bone labeled with tetracycline were studied with ultraviolet microscopy. The data indicate that avascular necrosis of the proximal fragment occurs after conventional Obwegeser-Dal Pont sagittal split osteotomy. Viability of the fragment was maintained by using a musculoperiosteal pedicle on the proximal fragment.

Animals↗
PubMed1985

Selective absorption of ultraviolet laser energy by human atherosclerotic plaque treated with tetracycline.

Tetracycline is an antibiotic that absorbs ultraviolet light at 355 nm and preferentially binds to atherosclerotic plaque both in vitro and in vivo. Tetracycline-treated human cadaveric aorta was compared with untreated aorta using several techniques: absorptive spectrophotometry, which demonstrated a distinct absorptive peak at 355 nm in tetracycline-treated plaque that was absent in treated normal vessel; ultraviolet microscopy, which showed that treated atheroma acquired the characteristic fluorescence of tetracycline under ultraviolet light; and tissue uptake of radiolabeled tetracycline, which showed 4-fold greater uptake by atheroma than by normal vessel. In addition, intravenous tetracycline administered to patients undergoing vascular surgery demonstrated characteristic fluorescence in surgically excised diseased arteries. Because of tetracycline's unique properties, we exposed tetracycline-treated and untreated aorta to ultraviolet laser radiation at a wavelength of 355 nm. We found enhanced ablation of tetracycline-treated atheroma compared with untreated atheroma. The plaque ablation caused by ultraviolet laser radiation was twice as extensive in tetracycline-treated vs nontreated plaque (2.2 +/- 0.25 mm vs 1.3 +/- 0.55 mm, p less than 0.017). This study demonstrates the potential of tetracycline plaque enhancement for the selective destruction of atheroma by ultraviolet laser radiation.

Absorption↗
PubMed1996

3D resolved two-photon fluorescence microscopy of living cells using a modified confocal laser scanning microscope.

Non-linear 3D imaging of fluorophore-labelled vital cells has been performed by femtosecond near infrared (NIR) microscopy. Ultraviolet and visible transitions of intracellular fluorophores, such as Fura-2, Calcium Green, Rhodamine 123 and fluorescent microspheres, were excited via simultaneous absorption of two 780 nm photons provided by a tunable Ti:Sapphire laser. The femtosecond laser was coupled to a conventional upright Zeiss confocal laser scanning microscope expanding its one-photon capabilities to 3D resolved two-photon microscopy. Pinhole-free non-linear 3D imaging was possible with 400 nm lateral and approximately 1 micron axial resolution. Axial resolution could be further improved by using an additional detection pinhole. The NIR average power and pulse width at the sample were adjusted to be 1-4 m W and 150-200 fs, respectively. Higher power levels resulted in cell damage as demonstrated by photoinduced lysis of human erythrocytes. The powerful capabilities of this universal microscope were demonstrated by 3D imaging of two-photon excited fluorophore-labelled macrophages during phagocytosis of fluorescent microsized beads.

Erythrocytes↗
PubMed1963

ULTRAVIOLET AND PHASE MICROSCOPY OF SPORULATING SACCHAROMYCES.

Miller, Glendon R. (Southern Illinois University, Carbondale), Dan O. McClary, and Wilbert D. Bowers, Jr. Ultraviolet and phase microscopy of sporulating Saccharomyces. J. Bacteriol. 85:725-731. 1963.-During active growth, the cytoplasm of yeast cells is densely absorbent to ultraviolet light at 260 mmu, whereas the nucleus is only faintly so, and the vacuole is nonabsorbent. After 24 hr on presporulation medium (about the age of transfer to acetate sporulation medium), the cells manifest many characteristics of starvation. The cytoplasm is weakly absorbent to ultraviolet light except for a dense zone immediately surrounding the vacuole and one or two groups of highly refractile granules clustered on one or both sides of the juncture of the nucleus and the vacuole. After several hours on the acetate sporulation medium, the cells undergo a progressive vacuolation until four or more large vacuoles appear, separated by granular cytoplasm. The nucleus is obscured to ultraviolet light during the vacuolation stage, at which time previous studies have shown its division to occur, and remains so during the rest of the cycle. Photographs of densely granulated cells, at various wavelengths of ultraviolet and visible light, indicated several different types of granules with respect to their absorption spectra. With continued development of the ascus, the granules increase in number until they fill the entire cell and obscure the vacuoles, after which they condense into a compact mass, leaving much of the cell empty. Spores emerge from the granular mass as separate, ultraviolet-absorbent regions without distinguishable cell walls, which seem to be the last structures formed. The rudimentary spores contain a central cluster of dense granules and are separated within the ascus by optically dense, granular partitions which diminish as spore walls are laid down. With the maturing of the ascus, the granules and epiplasm disappear, and the ascus wall is drawn tightly around the more or less homogeneously absorbent spores.

Cell Nucleus↗