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Biomedical subjects

H W Tiffe

Publications and source records attributed to H W Tiffe.

10 recordsLinked to original sources
PubMed1991

[The effect of magnetic resonance treatment on chicken embryos].

Nuclear Magnetic Resonance (NMR) is of increasing diagnostic importance especially in human medicine. To evaluate possible side effects of this technology, embryonated chicken eggs were used as a model. Different fields (static magnetic field [1 oder 4 T], variable magnetic field [gradient] or high frequency field) were applied before the beginning and at the fifth day of incubation for different times (18.8, 37.6, 56 or 75.1 min, resp.). According to the criteria embryo-mortality, hatching-rate or vitality of the chickens, influences of the NMR-treatment were not observed.

Animals↗
PubMed1987

[Definitions of pulse sequences and parameter weightings in the NMR tomogram].

Due to the different possibilities of image creation in MR tomography there is no clear terminology of pulse sequences and MR images. This paper tries to define the designation of pulse sequence parameters in a practical way and to specify the term "parameter weighting of MR images". Starting with general definitions, special definitions for CNS and liver are elaborated.

Central Nervous System↗
PubMed1979

Spectral changes of the fluorescent acriflavine--(Feulgen) DNA dye complex at different temperatures: application of a new cryostat for measurements in reflected and transmitted light.

The fluorometric behaviour of cellular objects is influenced during excitation by two nearly independent phenomena: (1) by the photochemical reaction of the DNA/AF dye complex, and (2) by the energy transfer among several DNA/AF dye complexes. Both processes show a distinct temperature-dependent behaviour and can therefore be characterized by the analysis of the fluorescence spectra at different temperatures. All microfluorometric measurements were performed with a self-constructed cooling device. The cryostat permits measurements of the cellular fluorescence within a range of temperatures between 4 K and 300 K. The cooling unit operates in accordance with the 'Continuous Flow Principle' and allows the application of objectives up to a numerical aperture of 0.6.

Acridines↗
PubMed1979

The evaluation of cell nuclei staining parameters regarding the reproducibility of fluorescence measurements.

The present methodological study is an attempt to optimize the staining parameters for a quantitative DNA determination of fluorescent cells. The application of pure dyes and a precise control of the staining procedure are preliminary conditions which have to be fulfilled, because the reproducibility of measurements is in this connection the most important criterion for a quantitative DNA related analysis of cell population. Chicken erythrocytes and isolated nuclei were applied as biological test objects. The staining procedure with acridine derivatives (acriflavine, proflavine, rivanol) was performed in accordance with the fluorescence-Feulgen reaction. The influence of staining parameters, such as (1) pH and (2) dye concentration of the staining solution, were evaluated regarding the spectral behaviour, the total fluorescence intensity, and the reproducibility of results.

Acriflavine↗
PubMed1977

A microscope stage sample holder for microfluorometric measurements of biological specimen in the range of temperature between 3.5 to 300 K.

A cryostat was constructed, which permits measurements of the intracellular fluorescence within a range of temperature between 3.5 to 300 K. The cooling unit operates in accordance with the "Continuous Flow Principle" and allows the application of objectives up to a numerical aperture of 0.6. It results from measurement of BAO Feulgen stained nuclear DNA, that a decrease of fluorescence intensity is caused by two different mechanisms: (1) There is a highly temperature dependent effect, originating from phenomena of solid physics, and (2) a second effect, which is almost temperature independent, and can be explained as a photochemical reaction.

Cell Nucleus↗
PubMed1975

Microfluorometric measurement at low temperature.

A cooling chamber for microfluorometric measurement is described, which allows to cool under a microscope a biological sample till 77 K and to measure it with an objective of a numerical aperture 0.6. From first experiments with BAO (5)-stained Tradescantia pollen it can be concluded, that experiments in this range of temperature open new aspects regarding the interpretation of microfluorometric phenomena.

Cold Temperature↗