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E Fröhlich

Publications and source records attributed to E Fröhlich.

At least 37 records · Page 2Linked to original sources
PubMed1998

Mammalian Bax triggers apoptotic changes in yeast.

Apoptosis is co-regulated by the conserved family of Bcl-2-related proteins, which includes both its agonists (Bax) and antagonists (Bcl-X(L)). A mutant strain of the yeast Saccharomyces cerevisiae has been shown to express all morphological signs of apoptosis. Overexpression of Bax is lethal in S. cerevisiae, whereas simultaneous overexpression of Bcl-X(L) rescues the cells. We report that overexpression of mammalian Bax in a S. cerevisiae wild type strain triggers morphological changes similar to those of apoptotic metazoan cells: the loss of asymmetric distribution of plasma membrane phosphatidylserine, plasma membrane blebbing, chromatin condensation and margination, and DNA fragmentation. Simultaneous overexpression of Bcl-X(L) prevents these changes. We demonstrate that Bax triggers phenotypic alterations in yeast strongly resembling those it causes in metazoan apoptotic cells.

Animals↗
PubMed1998

The eyes of deep-sea fish. II. Functional morphology of the retina.

Three different aspects of the morphological organisation of deep-sea fish retinae are reviewed: First, questions of general cell biological relevance are addressed with respect to the development and proliferation patterns of photoreceptors, and problems associated with the growth of multibank retinae, and with outer segment renewal are discussed in situations where there is no direct contact between the retinal pigment epithelium and the tips of rod outer segments. The second part deals with the neural portion of the deep-sea fish retina. Cell densities are greatly reduced, yet neurohistochemistry demonstrates that all major neurotransmitters and neuropeptides found in other vertebrate retinae are also present in deep-sea fish. Quantitatively, convergence rates in unspecialised parts of the retina are similar to those in nocturnal mammals. The differentiation of horizontal cells makes it unlikely that species with more than a single visual pigment are capable of colour vision. In the third part, the diversity of deep-sea fish retinae is highlighted. Based on the topography of ganglion cells, species are identified with areae or foveae located in various parts of the retina, giving them a greatly improved spatial resolving power in specific parts of their visual fields. The highest degree of specialisation is found in tubular eyes. This is demonstrated in a case study of the scopelarchid retina, where as many as seven regions with different degrees of differentiation can be distinguished, ranging from an area giganto cellularis, regions with grouped rods to retinal diverticulum.

Animals↗
PubMed1998

[Native and signal-enhanced power Doppler sonography for characterization of liver lesions].

PURPOSE: To evaluate the characterisation of liver lesions using power Doppler sonography before and after intravenous injection of the ultrasound contrast agent Levovist. MATERIALS AND METHODS: 39 patients with 41 liver lesions (10 haemangiomas, 2 focal nodular hyperplasias (FNH), 2 focal fatty infiltrations, 1 echinococcal lesion, 11 hepatocellular carcinomas, 14 metastases and one cholangiocarcinoma) were evaluated prospectively. Power Doppler images before and after intravenous injection of the ultrasound contrast agent Levovist were analysed by two radiologists and one gastroeterologist, who subjectively classified the distribution (peripheral, central, diffuse) and amount (none, minimal, moderate and strong) of flow pattern in each sonographic examination. Histological verification was obtained in all liver lesions, except in haemangiomas, where MR imaging and in one FNH where scintigraphy was regarded as sufficient proof. RESULTS: On the whole, power Doppler sonography after contrast injection was superior to unenhanced power Doppler-sonography in 20 liver lesions and equal in 7. After contrast injection, previously visible flow was enhanced in 14 patients, in 6 lesions flow was detected, which was not seen before in the power mode. Moderate or strong flow signals were detected before contrast injection in 8/26, post contrast injection in 18/26 malignant tumours. Contrawise, 13/15 benign lesions did show any or only minimal flow signals before and 10/15 after contrast injection. CONCLUSION: Intratumoural flow signals favour a malignant tumour. The absence of flow signals is a frequent finding in benign lesions but does not rule out malignancy.

Carcinoma, Hepatocellular↗
PubMed1997

A yeast mutant showing diagnostic markers of early and late apoptosis.

A Saccharomyces cerevisiae mutant in cell division cycle gene CDC48 shows typical markers of apoptosis: membrane staining with annexin V, indicating an exposure of phosphatidylserine at the outer layer of the cytoplasmic membrane; intense staining, using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling method, indicating DNA fragmentation; and chromatin condensation and fragmentation. The coordinate occurrence of these events at different locations in the cell, which have no obvious connection except their relation to apoptosis, implies the presence of the molecular machinery performing the basic steps of apoptosis already in yeast. Saccharomyces cerevisiae may prove a suitable model to trace the roots of apoptosis.

Adenosine Triphosphatases↗
PubMed1997

[A model of integrated partial inpatient rehabilitation].

This article deals with a new form of rehabilitation in Germany: the partly inpatient rehabilitation. This kind of rehabilitation comprises an offer for regular inpatient rehabilitation excluding overnight stay, breakfast and evening meal. In total the quasi inpatient rehabilitation is qualitatively equal to regular inpatient rehabilitation in respect of rehabilitative outcome. This new kind of rehabilitation contributes to a flexible and requirements-oriented health service in the German rehabilitation system. In this respect, "quasi inpatient rehabilitation" seems to be a valuable complement to traditional inpatient and out-patient rehabilitation, though quasi inpatient rehabilitation cannot generally replace traditional rehabilitation.

Adult↗
PubMed1996

Rod outer segment renewal in the retinae of deep-sea fish.

Outer segment renewal involves the synthesis of disc material in the photoreceptor inner segments, the shedding of the tips of the photoreceptor outer segments, and their phagocytosis by the retinal pigment epithelial cells. It has been suggested that in the retinae of deep-sea fish no renewal of outer segments may take place. In order to assess outer segment renewal in deep-sea fish retinae we counted (i) periciliary vesicles in rod inner segments as a parameter for disc-synthesis activity and (ii) phagosomes in retinal pigment epithelial cells as a parameter of shedding and phagocytosis in 12 species of deep-sea fish with multibank or single bank retinae. We also measured the lengths of rod outer segments in order to evaluate the balance between synthesis and phagocytotic activity. In four of these species (Synaphobranchus kaupi, Nematonurus armatus, Coryphaenoides guentheri and Halosauropsis macrochir) we further recorded size-related changes of these parameters and their relation to the position of a given rod within the banks in the retina. The number of periciliary vesicles was highest in inner segments of the most vitread bank and in the periphery of the retina. Phagosomes were most abundant in retinal pigment epithelial cells of the central retina. Long rod outer segments were most frequently recorded in the peripheral retina indicating that in this region new synthesis may outbalance shedding. Vitread rod outer segments were only slightly longer than sclerad ones. Larger animals had shorter rod outer segments than small ones. We present evidence that rod outer segment renewal takes place in the retina of all deep-sea fish. Vitread rods may be more active in this respect than sclerad ones.

Animals↗
PubMed1995

Mammalian Müller (glial) cells express functional D2 dopamine receptors.

Dopamine plays important functional roles in the vertebrate retina. Here we show that functional D2 dopamine receptors are present on mammalian retinal Müller (glial) cells. Using an antiserum directed to two oligopeptides predicted from rat D2 receptor DNA, patchy label was demonstrated immunocytochemically on virtually all Müller cells enzymatically isolated from guinea-pig and rat retinae. Application of exogeneous dopamine to voltage-clamped isolated living guinea-pig Müller cells caused either a decrease (40%), an increase (32%), or no change (28%) of the input resistance of the membrane. The D2 receptor agonist quinelorane caused an increase of the membrane's input resistance in 100% of the cells. This effect was completely blocked by the D2 receptor antagonist S(-)-sulpiride. When all voltage-activated K+ channels except the delayed rectifiers were blocked by Ba2+, quinelorane had no effect. Further, the reversal potentials of the responses were near the potassium equilibrium potential. We conclude that the activation of Müller cell D2 receptors closes (inwardly rectifying) K+ channels. The presence of functional dopamine receptors on mammalian Müller cells may have important consequences for retinal K+ clearance, and thus, for information processing in the retina.

Animals↗
PubMed1995

Patterns of rod proliferation in deep-sea fish retinae.

In a sample of 37 species of deep-sea fish species from the sea floor of the Porcupine Seabight and the Gobal spur (North Atlantic) we investigated the overall structure of the retina with special respect for the organization of rods, their length and their arrangement in multiple banks. Using an immunocytochemical marker for cell proliferation (PCNA) we studied the mechanisms of rod proliferation, and, by means of serial section reconstruction followed their integration into the existing population of rods. Furthermore, in three different species we have observed growth related changes in retinal thickness, rod density and proliferation activity. We found evidence for two different principles for the organization of rods in these deep-sea fish retinae. In the first group of species represented by Nematonurus armatus and Coryphaenoides guentheri we found rods to be rather short (20-30 microns) and arranged in three and more banks. In these species rod proliferation occurred in a single band of cells immediately vitread of the external limiting membrane, thus showing a high degree of spatial and temporal order. In these species, young rods are inserted just sclerad of the external limiting membrane and the older outer segments pushed away from the incoming light towards the back of the eye. This may be linked to a progressive loss of function of the older rods and might represent an alternative mechanism to the disk shedding in other vertebrates. In the second population (e.g. Conocara macroptera, Alepocephalus agassizii) we observed considerably longer rod outer segments (60-80 microns) forming no more than two layers. These retinae had rod precursors arranged in disseminated clusters throughout the outer nuclear layer indicating the lack of clear spatio-temporal order in mitotic activity along with a more statistical pattern of integration of the newly formed outer segments. In our sample of species both populations were of about equal size suggesting that the two mechanisms are equally effective and may have arisen independently.

Animals↗
PubMed1995

Efficiency of various dissociation methods for the preparation of thyroid single cell suspensions.

For comparison of the physiological potential of single thyroid cells versus cells integrated into follicles it would be ideal to work with suspensions consisting exclusively of single cells instead of a mixture of single cells and follicle fragments. In this study, various techniques for the isolation of single cells have been tested for their effect on cell viability, the ultrastructure of the isolated cells, the percentage of single cells and the ability of these cells to form follicles in culture. In addition, the cells were characterized for the preservation of their morphology and the ability to respond to TSH by comparing their immunocytochemical staining pattern with anti-vimentin and anti-ras p21 antibody to that of the intact thyroid tissue. Dispase treatment of thyroid tissues alone produced suspensions with a relatively small proportion of single cells. These cells stained with anti-vimentin and anti-ras p21 antibody to a similar percentage as thyroid cells in the intact gland. A combination of dispase treatment with either filtration or trypsin treatment severely compromised the viability of the cells. A high proportion of single cells with a good viability could be obtained either by centrifugation of dispase treated tissues or by culturing of dispase treated tissues as monolayers and subsequent detachment from the culture vessels with trypsin. Whereas the immunological staining with anti-vimentin and anti-ras oncogene antibody in the centrifuged cells resembled that of intact tissue, cells cultured as monolayers reacted differently. The differences in the immunological staining were still observed when the cells which had been grown as monolayers were stimulated with TSH. Differential centrifugation appeared to be the ideal method for the isolation of unaltered and viable single cells but is a rather laborious method to obtain larger amounts of single thyroid cells.

Animals↗
PubMed1995

[The value of fine needle puncture in adrenal gland tumors].

UNLABELLED: The value of fine needle biopsy (FNB) in adrenal masses was investigated in 33 patients presenting with such masses. Representative material was obtained 18 times from 19 patients with a history of tumour. 4 of them were diagnosed to be genuinely benign and 14 to be genuinely malignant. Further representative material was obtained 13 times from 14 patients with incidental findings of adrenal masses. The material gained by puncturing was classified correctly as benign in 9 cases, and twice it was considered benign although the tumours later proved malignant. In one case a clinically not suspected malignant lesion was detected by FNB, while in another case a malignant lesion was suspected by FNB, whereas a benign tumour was proven by means of surgery. The share of malignant diagnoses corresponded with the size of tumour, ascertained by the application of ultrasound or CT. The rate of malignant adrenal masses, which were found incidentally, increased from 7 cm onwards; however, the rate of malignant adrenal masses obtained from patients with a history of tumour increased distinctively already from 4 cm onwards. From 11 patients out of 33, adrenal tissue was obtained and classified as benign lesion (adenoma), although, by means of FNB and the conditions for reasons of method, a well differentiated carcinoma cannot be excluded. CONCLUSION: FNB is indicated for non-functioning tumours examined in patients with a history of tumour, furthermore, for incidental findings of the size between 4-6 cm. A diagnostic approach to adrenal masses is suggested.

Adrenal Cortex Neoplasms↗
PubMed1995

Immunocytochemical and immunoelectron microscopic demonstration of cathepsin B in human malignant melanoma.

Proteases are known to enhance the spread of tumour cells. Possible sources of these proteases are the tumour cells themselves or fibroblasts in the tumour tissue. Immunological staining with anticathepsin B antibody indicates that the subcellular distribution of cathepsin B in tumour cell lines differs from that in normal liver. The aims of this study were: (i) to show whether different types of melanoma differ in their production of cathepsin B; (ii) to identify the cathepsin B-producing cells; and (iii) to determine the subcellular distribution of cathepsin B in melanoma cells. All types of melanomas contained cell regions stained with anticathepsin B antibody. The intensity of the stain and the number of cells reacting with anticathepsin B antibody depended on the size of the tumour but not on the type of melanoma. Epithelioid cells stained more intensely with anticathepsin B antibody than spindle-shaped cells. Cells staining with anticathepsin B antibody were almost exclusively tumour cells. Anticathepsin B stain was located mainly in vesicular structures which did not contain a filamentous matrix. Additional anticathepsin B stain was detected at the extracellular spaces. Hypomelanotic melanoma cells, mainly of the epithelioid type, produced most of the cathepsin B. Cathepsin B may be involved in both the degradation of possibly abnormal melanosomes and the focal degradation of the extracellular matrix.

Antigens, Neoplasm↗
PubMed1995

Basal lamina formation by porcine thyroid cells grown in collagen- and laminin-deficient medium.

Porcine thyroid cells isolated by dispase treatment were cultured in either (a) Matrigel, (b) agarose with the addition of different combinations of basic fibroblast growth factor and laminin, or (c) on agarose-coated dishes. The formation of follicles and the presence of a basal lamina was investigated by routine electron microscopy of Araldite-embedded material and by light and electron microscopical immunocytochemical detection of the basal lamina components, laminin and collagen type IV. After 10 days of culture in Matrigel or agarose, a basal lamina-like structure surrounded most follicles. Follicles of cells growing in agarose and overlaid with a medium containing thyrotropin and overlaid with a medium containing thyrotropin and fibroblast growth factor showed a fluorescent band at the basal side of the follicles after immunocytochemical staining with anti-laminin and anti-collagen antibodies. Routine electron microscopy showed that a basal lamina-like structure lined the outside of the follicle. This structure could be subdivided into a lamina lucida and a lamina densa. Electron microscopical immunogold labelling revealed that immunologically detectable laminin was confined to the lamina densa. These findings suggest that even in the absence of basal lamina components in the culture medium, thyroid cells are able to form follicles with a regular basal lamina when they are cultured in a three-dimensional environment.

Animals↗
PubMed1993

Immunelectron microscopic localization of cathepsin B in human exocrine glands.

The distribution of the lysosomal enzymes cathepsin B, lysozyme, chymotrypsin, and neutrophil elastase was examined in eccrine, apocrine, and sebaceous glands using a postembedding immunogold labeling procedure. Various amounts of cathepsin B were detected in all glands. Lysozyme, however, was detected in apocrine glands only. The other two lysosomal enzymes were not detectable immunologically. In apocrine and eccrine glands, anti-cathepsin B antibody labeled all secretory granules. In sebaceous glands, only the peripheral layer of cells showed immunological activity for cathepsin B. In apocrine glands, granules containing remnants of cristae were more intensively labeled than those lacking cristae which supports the assumption that both granules are derived from mitochondria by acquiring lysosomal enzymes. The enzymes convert mitochondria to granules with cristae and finally to granules without cristae. Thus the difference in morphology is part of a spectrum of the degradation of mitochondria to granules.

Apocrine Glands↗
PubMed1993

[Treatment of intraperitoneal abscess--ultrasound controlled percutaneous or surgical drainage?].

In a retrospective study the effectiveness of ultrasound guided percutaneous drainage (n = 36) was compared with that of surgery (n = 38) in the treatment of intraperitoneal abscesses. The treatment was successful in 95% while 5% of the patients in both groups died from progressive septic shock; one complication in each group occurred. There is a significant difference in terms of hospital stay (18 vs. 26 days) that favor the percutaneous treatment.

Abscess↗
PubMed1993

[Ultrasound-controlled percutaneous drainage of subhepatic liver abscess after conventional cholecystectomy].

From February 1984 to August 1991 subhepatic abscesses were detected by ultrasound in 7 patients with fever following conventional cholecystectomy. Cholecystectomy had been performed in all these patients 6 to 27 days previously. All patients had received antibiotic prophylaxis at the time of cholecystectomy. Three of the 7 patients were at first afebrile, later on again febrile. In the remaining 4 of the 7 patients antibiotic treatment was continued in the face of persistent fever. Percutaneous catheter drainage was performed in all patients. In all of the 7 cases the subhepatic abscesses resolved completely within 10 days to 7 weeks.

Aged↗
PubMed1992

[Ultrasound-proven adrenal gland tumor. References for diagnostic management].

Due to the increasing number of ultrasonographic examinations, tumors of the adrenal glands are being detected more and more often. In the present paper, suggestions for the further diagnostic evaluation are made: in the case of sonographically detected solid tumors of the adrenals, computed tomography is the next procedure of choice. If CT scan also fails to enable an unequivocal diagnosis, the next step must be laboratory investigations. Hormone-producing tumors, irrespective of size, as well as non-hormone-producing tumors larger than 6 cm in diameter or symptomatic neoplasms are all treated by surgery. In the case of an oncological patient with an asymptomatic non-hormone-producing tumor, differential diagnosis via needle aspiration should be attempted in all tumors measuring less than 6 cm in diameter. In the event of an incidental finding, fine needle aspiration is performed only in lesions measuring between 4 and 6 cm; for tumors of less than 4 cm, we consider a wait-and-see approach, with follow-up examinations at 3-month intervals to be justified.

Adrenal Gland Neoplasms↗