Biomedical subjects

J Bereiter-Hahn

Publications and source records attributed to J Bereiter-Hahn.

At least 109 records · Page 6Linked to original sources

PubMed1977

[Selective contrast enhancement of microscopical specimen by optical procedures for automatized quantitative image analysis (author's transl)].

One of the most important problems in automatic image analysis is the discrimination of features by, a certain range of grey levels. To obtain as many as possible different grey levels sufficient contrast is achieved mainly by specific staining. Alternative and supplementary methods are some micrscopical methods, not routinely used. Interference microscopy, interference reflexion microscopy and microfluorimetry are discussed in detail. These optical procedures enhance the contrast of specimen specifically without the necessity for the application of specimen specifically without the necessity for the application of sophisticated staining methods. In interference contrast, tissues can be separately detected by grey level discrimination due to varying concentration of dry mass; this is shown for a cornifying part of fish skin (breeding tubercle of Rutilus rutilus L.). Furthermore, very small amounts of dry matter can be determined with high precision, as demonstrated for a single tissue culture cell (XTH-cell). Automatisation of image analysis provides a unique opportunity for routine application of interferometric measurements. The principles of the procedures are outlined. By interference reflexion microscopy cellular attachment areas to a glass surface are visualized, providing a powerful tool in cellular diagnosis based on grey level discrimination (darkest parts correspond to zones of closest contact to the substratum). A fast migrating lymphocyte and stationary endothelial cells have been chosen for demonstration. Various histochemical problems can be solved elegantly by fluorescence methods, e.g. mitochondria in living cells are specifically stained by a fluorochrome (DASPMI) and the distribution of fluorescence intensity can be followed within the mitochondrial population of a cell. Fluorescence was recorded from fotographic negatives taken with a fluorescence microscope. Additionally a short comment is given on the application of polarisation microscopy for feature detection.

Animals↗

PubMed1976

Dimethylaminostyrylmethylpyridiniumiodine (daspmi) as a fluorescent probe for mitochondria in situ.

An investigation has been made on the properties of dimethylaminostyrylmethylpyridiniumiodine (DASPMI), its reaction with isolated pigeon heart mitochondria and its suitability as a vital strain for mitochondria in situ. DASPMI is a low toxicity specific vital stain for mitochondria in living cells. In vitro dye concentrations over 6 nmol/mg protein inhibit fast (state 3) respiration after a preincubation time of more than 5 min in the presence of substrate. No uncoupling was observed. Energization of pigeon heart mitochondria by addition of ATP or various substrated yields an average 8.5-fold increase in fluorescence intensity in relation to DASPMI-stained mitochondria that are under anoxia, substrate deficiency, or under the influence of respiratory inhibitors, or uncouplers. The alterations in fluorescence intensity are not primarily due to ion movements or pH changes. The amount of dye (2.96+/-0.8 nmol) yielding maximal fluorescence response with 1 mg mitochondrial protein remains constant during energization of mitochondria. As indicated by electron microscopic studies the observed changes in emission intensity may be related to changes in the fine structural organisation of cristae. A remarkable difference exists between isolated mitochondria and mitochondria in situ with respect to the reaction to cyanide. According to the reported results DASPMI will be a useful probe for the investigation of mitochondrial activities in living cells.

Adenosine Diphosphate↗

PubMed1975

Pigment movements in fish melanophores: morphological and physiological studies. V. Evidence for a microtubule-independent contractile system.

A pressure device has been used to obtain information about the forces involved in the maintenance of the aggregated state of melanophores of the angelfish, Pterophyllum scalare. Single aggregated melanophores of isolated scales were submitted to mechanical compression with forces ranging from 50-320 mup. As a function of the gradually increasing force melanophores disperse their pigment, the degree of dispersion being proportional to the intensity of the force. When microtubules are destroyed by treatment with 0.3 mM vinblastine in KCl solution, pigment dispersion in response to the external force is similar to that observed in KCl alone. After changing the medium to NaCl solution, melanin granules remain concentrated in the cell center; the force-induced melanosome dispersion, however, is significantly enhanced. Distinctly lower forces are required to produce an expansion equivalent to that observed in KCl solution. When the medium is changed to vinblastine-KCl again, the dispersion in response to the external force resembles that obtained before NaCl treatment. Removal of Ca++ and Mg++ ions by treatment with 2 mM EDTA or EGTA in Ringer's solution containing 0.1 mM adrenalin produces a remarkable enhancement of melanosome dispersion in response to increasing external force. This effect of EDTA or EGTA is completely reversible. When the medium is changed to normal Ca++-Ringer's, the force/dispersion curve resembles that obtained before EDTA or EGTA treatment. It is concluded that a state of equilibrium exists between the external force and an opposing force produced by the melanophore. The differences in the opposing force under different experimental conditions may be due to a "contractile component". This component seems to be independent of microtubules, as indicated by vinblastine experiments. It "contracts" under aggregating stimulus and "relaxes" under dispersing stimulus. From the data presented in this paper, the order of magnitude of the pressure developed by the contractile component in the completely aggregated state was calculated as between 5-7 p/cm2 in the relaxed state and about 20 p/cm2 during contraction. These values are comparable to those observed in other nonmuscular cells.

Animals↗

PubMed1974