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M Hafner

Publications and source records attributed to M Hafner.

53 records · Page 3Linked to original sources
PubMed1995

A purine-rich sequence in the human BM-40 gene promoter region is a prerequisite for maximum transcription.

BM-40 (osteonectin, SPARC [secreted protein, acidic, rich in cysteine]) is a highly conserved, matrix-associated protein that is found in basement membranes, bones and remodeling tissues throughout vertebrate evolution. We are reporting the characterization of the 5' end of the human BM-40 gene. Sequence comparison of the 5' region revealed significant homologies with the bovine and murine genes, including a purine-rich stretch composed of two boxes, GGA-box 1 and 2, separated by a pyrimidine-rich spacer element. Transfection analyses of the human BM-40 promoter provide strong evidence that this region comprises several distinct regulatory domains, to which different functions can be assigned. GGA-box 1 is thereby absolutely required and sufficient by itself for maximal BM-40 transcriptional activity, whereas the spacer element has a down-regulatory effect. Comparative transfection analyses in human cell lines, positive or negative for BM-40 transcripts, indicate that the GGA-box sequences in the human promoter, in contrast to the bovine promoter, do not significantly contribute to cell-type specific expression in human cells.

Adenosine↗
PubMed1994

Mechanisms involved in metastasis enhanced by inflammatory mediators.

The enhancement of tumor metastasis by concurrent inflammatory processes is mainly due to the cytokines TNF and IL-1. In the case of TNF this effect is not restricted to metastasis models as measured by in vivo colony formation but also found in experimental model systems of spontaneous metastasis. Direct effects on the tumor cells or interference with the host NK cell system did not seem to account for the observed TNF effect. Experimental evidence from different test systems rather points to TNF- or IL-1-induced enhanced adhesion of tumor cells to the endothelial cell layer as the underlying mechanism. Blocking of integrin-matrix interactions with monoclonal antibodies or competing peptides inhibited tumor cell adhesion to endothelioma cells in vitro and lung colony formation of tumor cells in vivo.

Animals↗
PubMed1993

[Differential diagnosis of chronic gait disorders of neurologic origin in old age].

The differential diagnosis of chronic gait difficulties with falls in the elderly, due to neurological diseases, is discussed. The spectrum is quite wide and encompasses central and peripheral pathologies of the nervous system. For centrally induced gait difficulties auxiliary examinations correspond to those used in the evaluation of dementia.

Aged↗
PubMed1992

Cellular localizations and processing of the two molecular forms of the Hodgkin-associated Ki-1 (CD30) antigen. The protein kinase Ki-1/57 occurs in the nucleus.

The Ki-1 antibody not only detects a Hodgkin-associated membrane molecule of 120 kd (Ki-1/120 = CD30), but also reacts with an independently synthesized molecule of 57 kd (Ki-1/57) that only occurs intracellularly. Hodgkin's disease-derived cell lines L428 and L540 contain both Ki-1-reactive antigens, whereas others, e.g., U266/Bl myeloma cells, only express the intracellular Ki-1/57. The present immunoelectronmicroscopic analysis detected the Ki-1/57 antigen of U266/Bl cells not only in the cytoplasm, but also in association with the nuclear envelope, chromatin structures, and nucleoli. This Ki-1/57-specific type of labeling also was observed in L428 and L540 cells that, in contrast to U266/Bl cells, showed an additional staining of cell membranes and cytoplasmic vesicles. These results were confirmed by two independent methods: 1) cytocentrifuge preparations of isolated nuclei of L540 cells showed a spotted Ki-1-specific labeling, 2) immunoprecipitations demonstrated that the Ki-1/57, but not the Ki-1/120 antigen, was transferred into the nuclei of L540 and U266/Bl cells, whereas the Ki-1/120 antigen with its 90-kd precursor remained in the non-nuclei fraction of L540 cells.

Antigens, CD↗
PubMed1989

[Neurological gait changes in old age: basic principles, senile gait].

Gait abnormalities and falls often occur in the elderly, and it is often difficult for the practitioner to distinguish between a specific disease causing disordered gait and gradual changes due to "normal" involution. Based on the biomechanics and the neural control mechanisms of normal adult gait, characteristics of the "senile gait" are described. The senile gait abnormality is regarded as a clinical entity ascribed to age alone and its many cerebellar, extrapyramidal and cerebrofrontal changes, all of which may give rise to disordered central programming of upright stance and gait. The need for a careful evaluation of the elderly patient's station and gait is stressed.

Aged↗
PubMed1989

Volume-controlled ventilation with superimposed high frequency ventilation during expiration in healthy and surfactant-depleted pig lungs.

In the healthy and surfactant-depleted lungs of five pigs the influence of different forms of high frequency ventilation superimposed on conventional mechanical ventilation during the expiratory phase of the ventilatory cycle (SHFVE) on gas exchange and cardiocirculatory parameters was investigated. Subsequently the effects of end-expiratory flushing (EF), i.e. cleaning the large airways and connecting tubes from the ventilator free from end-expiratory CO2, with a volume greater than the dead space of the large airways and connecting tubes was investigated. SHFVE and EF resulted in a significant improvement in CO2 elimination in both healthy and surfactant-depleted lungs. Furthermore, in stiff lungs, at a certain level of oxygenation and CO2 elimination, SHFVE produced the lowest peak and mean airway pressure without any additional depression of cardiocirculatory parameters.

Animals↗
PubMed1988

Wave of free calcium at fertilization in the sea urchin egg visualized with fura-2.

A wave front of increased free calcium traversing the egg at fertilization is demonstrated in the sea urchin Lytechinus pictus. The use of the fluorescent calcium chelator fura-2 in combination with low-light-level TV microscopy and image processing allows the visualization of the Ca2+ wave front with high spatial and temporal resolution. Such a wave is demonstrated as increased fluorescence after an excitation of 340-nm wavelength and as the reciprocal image in form of a reduced fluorescence when excited at 380 nm. The band-like appearance of the wave resembles the Ca2+ wave described for larger eggs of other species. In a dispermic egg the high resolution of the system used allows us to recognize two waves of Ca2+ originating from the respective points of sperm entry.

Animals↗
PubMed1988

Microtubules and Ca2+-sequestering membranes in the mitotic apparatus, isolated by a new method.

The mitotic apparatus of sea urchin embryos was isolated using a polyethylene glycol (PEG)/EGTA-medium. Such a procedure preserves the birefringence and the Ca2+ lability of the isolated mitotic apparatus. The method of isolation gives good preservation of the microtubules and of the intracellular Ca2+-transport system as visualized by a monoclonal antibody to a 46-kDa protein. Triple fluorescence studies allow a comparison of the relative locations of microtubules, Ca2+-sequestering membranes and chromatin (by Hoechst 33342) in the mitotic apparatus. We find that the Ca2+-sequestering membranes are concentrated mainly in the centers of the asters and do not follow the distribution of microtubules in the mitotic apparatus. Regulation of microtubules by Ca2+ may not depend on immediate contiguity of microtubules and the Ca2+-regulating sites.

Animals↗
PubMed1986

Visualization of the Ca-transport system of the mitotic apparatus of sea urchin eggs with a monoclonal antibody.

Monoclonal antibodies have been obtained to components of Ca(2+)-sequestering vesicles from the endoplasmic reticulum of HeLa cells by isolating hybridomas that were generated by the in vitro immunization of lymphocytes followed by fusion with plasmocytoma cells. One of these monoclonal antibodies specifically labels punctate structures which appear in the mitotic apparatus of sea urchin eggs at the beginning of prophase and disappear upon the completion of cytokinesis. The antibody inhibits the Ca(2+) uptake of the membrane system in vitro. It reacts with one 46-kDa protein out of the complex protein mixture from the membrane fraction. We take all this as evidence that in fact a specific Ca(2+)-transport system is part of the mitotic apparatus, that such a system is very conserved, and that it is most probably derived from the endoplasmic reticulum.

Journal Article↗
PubMed1985

[Aroma therapy].

Explore the source record for details and available documents.

Humans↗
PubMedDate not supplied

A new in vitro bioassay for cyst formation by renal cells from an autosomal dominant rat model of polycystic kidney disease.

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most frequent human inherited diseases. The main feature of the disease is the development of renal cysts, first occurring in the proximal tubules, and with time, dominating all segments of the nephron, leading to end-stage renal disease in 50% of the patients in their fifth decade of life. A therapy for polycystic kidney disease (PKD) has not yet been developed. Patients coming to end-stage ADPKD require long-term dialysis and/or transplantation. A suitable animal model to study ADPKD is the spontaneously mutated Han:SPRD (cy/+) rat, but a method to cultivate Han:SPRD (cy/+) derived renal cells which preserves their ability to form cyst-like structures in vitro has previously not been reported. Based on this well-characterized animal model, we developed a cell culture model of renal cyst formation in vitro. When renal cells of the Han:SPRD (cy/+) rat were isolated and cultured under conditions that prevent cell-substratum adhesion, large amounts of cyst-like structures were formed de novo from Han:SPRD (cy/+) derived renal cells, but only a few from control rat renal cells. In contrast, when cultivated on plastic as monolayer cultures, Han:SPRD (cy/+)-derived and control rat-derived renal cells were indistinguishable and did not form cyst-like structures. Immunohistochemical characterization of the cyst-like structures suggests tubular epithelial origin of the cyst-forming cells. The amount of cysts formed from Han:SPRD (cy/+)-derived renal cells grown in a stationary suspension culture is susceptible to modulation by different conditions. Human cyst fluid and epidermal growth factor both stimulated the formation of cysts from Han:SPRD (cy/+)-derived renal cells whereas taxol inhibited cystogenesis. In contrast, neither human cyst fluid nor epidermal growth factor affected the amount of cysts formed by control rat renal cells. As the culture model reported here allows not only the distinction of PKD-derived tubular epithelium from its normal counterpart, but also the modulation of cyst formation especially by Han:SPRD (cy/+)-derived renal cells, it might be a useful prescreening protocol for potential treatments for PKD and thus reduce the need for animal experiments.

Animals↗
PubMedDate not supplied

Inhibition of mitosis by an antibody to the mitotic calcium transport system.

Calcium ions are important in the regulation of mitotic apparatus assembly and in the control of chromosome movement. Changes in intracellular free calcium concentration, [Ca2+]i are achieved by an intracellular calcium-transport system which is highly conserved in different cell types. A membrane-bound protein of relative molecular mass (Mr) 46,000 (46K) is part of this transport system and has been implicated in the regulation of the [Ca2+]i changes associated with the course of mitosis. A monoclonal antibody against this 46K protein inhibits Ca2+-uptake into isolated Ca2+-sequestering membranes and specifically labels membranes associated with the mitotic apparatus of sea urchin embryos. Here we investigate the relationship between the intracellular calcium transport system and mitosis by injection of this monoclonal antibody into living mitotic sea urchin embryos. We find that after injection the intracellular free calcium increases up to 10(-6) M, the mitotic apparatus is rapidly destroyed and the cell is irreversibly blocked in its development.

Animals↗
PubMedDate not supplied

Role of adhesion molecules and platelets in TNF-induced adhesion of tumor cells to endothelial cells: implications for experimental metastasis.

Mechanisms for TNF-enhanced adhesion of tumor cells to endothelial cells were investigated for their in vivo relevance in a model of experimental metastasis. Mouse fibrosarcoma and thymoma cells were used to analyze TNF-modified adherence to three different mouse endothelioma cell lines and the results were compared to the in vivo colonization behavior of the tumor cells. TNF enhanced tumor cell adhesion in vitro and extravasation in vivo with similar characteristics. The role of different adhesion molecules in these experimental systems was tested. Blocking of ICAM-1, LFA-1, VCAM-1, E-selectin, and P-selectin did not reduce TNF-enhanced metastasis even though tumor cell adhesion in vitro was reduced. However, the correlation between inhibition of integrin binding and inhibition of metastasis achieved with competing peptides indicated an important role for extracellular matrix components in tumor cell attachment. Platelets play a dual role: although in vitro platelets prevented tumor cell adhesion to endothelial cells, in vivo platelet-depletion of mice reduced metastasis.

Animals↗