Biomedical subjects

M Kasper

Publications and source records attributed to M Kasper.

At least 19 recordsLinked to original sources

PubMed1996

Role of tissue factor in embryonic blood vessel development.

Tissue factor, a member of the cytokine-receptor superfamily and high-affinity receptor and cofactor for plasma factor VII/VIIa (ref. 1), is the primary cellular initiator of blood coagulation. It is involved in thrombosis and inflammation associated with sepsis, atherosclerosis and cancer, and can participate in other cellular processes including intracellular signalling, metastasis, tumor-associated angiogenesis, and embryogenesis. Here we report that inactivation of the tissue factor gene (TF) results in abnormal circulation from yolk sac to embryo beyond embryonic day 8.5, leading to embryo wasting and death. Vitelline vessels from null mice were deficient in smooth-muscle alpha-actin-expressing mesenchymal cells, which participate in organization of the vessel wall. This implies that tissue factor has a role in blood vessel development.

Animals↗

PubMed1996

Immunocytochemical evidence for a modulation of galectin 3 (Mac-2), a carbohydrate binding protein, in pulmonary fibrosis.

Galectin 3 is endogenous mammalian carbohydrate-binding protein with affinity for terminal beta-galactose residues, polylactosamine glycans, and ABH-blood group carbohydrate epitopes. To determine the distribution and regulation of galectin 3 during pulmonary injury, which is known to be accompanied by profound changes in the carbohydrate moieties of cell surface glycoproteins of alveolar cells, a rat model of irradiation-induced lung inflammation and repair was used. Immunocytochemistry showed that in normal rat lungs, galectin 3 was localized to alveolar macrophages, with weaker staining of bronchial epithelial cells. Shortly after irradiation-induced lung injury, when there is active proliferation of type II alveolar epithelial cells and re-epithelialization of alveolar basement membranes by type I cells, the total galectin concentration in the lung increased dramatically. This increase was due in part to an increased population of galectin 3-positive interstitial and alveolar macrophages. In addition, galectin 3 was expressed prominently at the surface of the newly formed type I alveolar epithelium and to lesser extent at the apical surface of type II cells. These findings suggest that the increased synthesis and secretion of galectin 3 during irradiation-induced lung injury, together with ligation of secreted lectin at the surface of alveolar epithelial cells, may play roles in pulmonary alveolar epithelial expansion and differentiation during injury and repair.

Animals↗

PubMed1996

Immunolocalization of cathepsin D in pneumocytes of normal human lung and in pulmonary fibrosis.

Cathepsin D expression has been assessed by immunohistochemistry and immunoelectron microscopy in fetal, normal adult and injured lungs of human beings. In addition to the well known positivity of alveolar macrophages and the bronchial epithelial cells, normal type I and to a lesser extent type II pneumocytes showed a granular, cytoplasmic staining pattern. Using immunogold labelling of lowicryl embedded human lung, cathepsin D was present in lysosomes of epithelial cells. Double immunofluorescence labelling employing type I and type II specific antibodies or lectins confirmed the epithelial staining for cathepsin D. At the terminal sac period during lung development cathepsin D appears in the alveolar epithelium. In fibrotic specimens, enhanced immunoreactivity was found in epithelial and non-epithelial cells. Proliferative epithelial formations were strongly stained with cathepsin D antibodies, whereas detached, desquamated epithelial cells were weakly positive or negative. We suggest that cathepsin D plays a role in the remodelling process during fibrogenesis.

Adult↗

PubMed1996

Expression of CD44 isoforms during bleomycin-or radiation-induced pulmonary fibrosis in rats and mini-pigs.

The distribution of CD44s and CD44v molecules in normal and injured lung tissue of rats and mini-pigs was studied by examining the immunohistochemical binding of monoclonal antibodies against CD44 isoforms. We showed that the expression of CD44v and CD44s varies greatly among different pulmonary fibrosis samples and that some tissues express either enhanced expression of CD44s, particularly in the interstitium and on alveolar macrophages, or very low levels of CD44v in the alveolar epithelium. Normal type II pneumocytes expressed the CD44s and CD44v molecules at the basolateral aspect of the cell. Such localisation favours a role for CD44 in epithelial cell-fibroblast interaction during lung development and repair.

Animals↗

PubMed1996

Upregulation of gap junction protein connexin43 in alveolar epithelial cells of rats with radiation-induced pulmonary fibrosis.

The degree of immunoreactive connexin43 (C x 43) in rat lung was evaluated during the development of radiation-induced pulmonary fibrosis in rat by a double immunofluorescence technique using polyclonal antisera to Cx43 and monoclonal antibodies to cytokeratins on cryostat sections. In normal rat lungs, Cx43 was detected in pneumocytes type II and I, in large blood vessel endothelia, in peribronchial smooth muscle cells, and in some peribronchial and perivascular interstitial cells. As early as 1 week after irradiation, enhanced immunoreactivity for Cx43 in the epithelial cells was detected. In severely injured lungs (about 3 months after irradiation), Cx43 was found also in the cytoplasm of type II pneumocytes. These findings were confirmed by western blot data. Western blot analysis also revealed increased phosphorylation of Cx43. It remains to be investigated whether the increased content of Cx43 in irradiated rat lung may be due to an enhanced number of gap junctions between type I and II alveolar epithelial cells.

Actins↗

PubMed1996

Distribution of von Willebrand factor in capillary endothelial cells of rat lungs with pulmonary fibrosis.

To determine the value of von Willebrand factor (vWF) antigen as a marker of endothelial injury in radiation-induced fibrosis of rat lungs, we studied endothelial immunoreactivity to antibodies against vWF using the indirect immunoperoxidase technique combined with morphometric analysis. Using immunoelectron microscopy of LR White embedded lung samples to detect vWF, immunogold-labelled Weibel Palade bodies were found in endothelial cells of capillary endothelium. The irradiated lungs showed a statistically significant elevation of vWF expression, ie, vWF positive endothelia per unit area, and a significant increase of vWF expression per unit of parenchyma as well. The results suggest that vWF antigen expression and the number of vWF positive structures is modulated under condition of injury in radiation-induced fibrosis.

Animals↗

PubMed1996

Changes in keratinocyte differentiation during accelerated repopulation of the irradiated mouse epidermis.

Epidermal stem cells accelerate their repopulation rate during fractionated irradiation. To study the changes in keratinocyte differentiation associated with radiation-induced repopulation, we investigated the expression of a panel of 14 monoclonal or polyclonal antibodies against keratins, involucrin and others, as well as the expression of 15 lectins in the irradiated mouse leg skin. Tissue samples were collected after 1, 2, and 3 weeks of daily irradiation with 3 Gy per fraction. Abnormal morphological appearance of the irradiated epidermis suggested disturbed terminal differentiation. Keratin 16 (K16) was negative in normal epidermis but intense staining was observed in the irradiated epidermis. Involucrin was expressed in the outmost suprabasal layers only in the normal epidermis but extended to the lower layers in the irradiated epidermis. The lectin binding patterns for agglutinins from Soybean, Dolichos biflorus, and Helix pomatia showed differences between the normal and the irradiated epidermis. From these characteristic changes in staining patterns we concluded that accelerated repopulation of the epidermis during fractionated irradiation is associated with a deficiency in terminal squamous differentiation.

Animals↗

PubMed1996

Tissue factor expression during human and mouse development.

In the adult organism the cellular distribution of tissue factor (TF) expression corresponds to biological boundary layers forming a hemostatic barrier ready to activate blood coagulation after tissue injury. Whether TF expression might also play a role in development is unknown. To determine the significance of TF in ontogenesis, we examined the pattern of TF expression in mouse development and compared it with the distribution of TF in human post-implantation embryos and fetuses of corresponding gestational age. At early embryonic periods of murine (6.5 and 7.5 pc) and human (stage 5) development, there was strong expression of TF in both ectodermal and entodermal cells. In situ hybridization and immunohistochemistry demonstrated that TF mRNA and protein were expressed widely in epithelial areas with high levels of morphogenic activity during organogenesis. Staining for TF was seen during ontogenetic development in tissues such as epidermis, myocardium, bronchial epithelium, and hepatocytes, which express TF in the adult organism. Surprisingly, during renal development and in adults, expression of TF differed between humans and mice. In humans, maturing stage glomeruli were stained for TF whereas in mice, TF was absent from glomeruli but was present in the epithelia of tubular segments. In neuroepithelial cells, there was a substantial expression of TF. Moreover, there was robust TF expression in tissues such as skeletal muscle and pancreas, which do not express it in the adult. In contrast, expression of the physiological ligand for TF, factor VII, was not detectable during early stages of human embryogenesis using immunohistochemistry. The temporal and spatial pattern of TF expression during murine and human development supports the contention that TF serves as an important morphogenic factor during embryogenesis.

Adult↗

PubMed1996

Immunohistochemistry of new type I alveolar epithelial cell markers of the rat.

The presence of pan-cadherin and the MEP-I antigen in normal and diseased rat lung was established by employing immunoperoxidase and double label fluorescence techniques. The binding of a mouse monoclonal antibody (MEP-1) reacting specifically with type I pneumocytes was assessed on paraffin sections of normal specimens as well as those with pulmonary fibrosis induced by bleomycin or radiation treatment. In injured alveolar epithelium, a diminished type I cell and a focal type II cell immunoreactivity was found. Electron microscopy of immunogold-labelled lung tissue confirmed the type I cell specificity of MEP-1. In severely injured pulmonary parenchyma MEP-1-negative areas occurred, which were also negative with the type II pneumocyte marker Maclura pomifera lectin. Similarly, a polyclonal pan-cadherin antibody uniformly decorated luminal surfaces of alveoli except the type II pneumocytes. Furthermore, pleural mesothelial cells, bronchiolar epithelial cells, endothelial cells of large blood vessels and alveolar macrophage surfaces exhibited pan-cadherin immunoreactivity. After injury, a remarkable loss of pan-cadherin immunoreactivity in the MEP-1-positive type I epithelial cells was detectable. These findings suggest that characterization of normal alveolar epithelial cells and monitoring of the epithelial remodelling in pulmonary pathohistology are sufficiently described by the antibodies MEP-1 anti pancadherin.

Animals↗

PubMed1996

Alterations in the alveolar epithelium after injury leading to pulmonary fibrosis.

This review discusses current knowledge of the involvement of the alveolar epithelium in tissue remodelling during fibrogenesis. The purpose of the present paper is to give an overview, including the authors' own results, of knowledge of ultrastructural alterations, proliferation kinetics and phenotypic changes of pneumocytes in experimental and clinical pathology of pulmonary fibrosis. After lung injury, the alveolar epithelial cells show ultrastructural alterations, hypertrophy and hyperplasia, and a modulation of a series of structural and membrane proteins such as cytoskeletal changes, loss or de novo expression of epithelial adhesion molecules, and altered lectin binding. Furthermore, enhanced secretion of proteases, of cytokines and other soluble factors can be observed in the alveolar epithelium. These findings suggest the contribution of the epithelium in the remodelling process to be greater than expected. Estimations of the cell kinetics show that type II pneumocytes have the proliferative capacity to restore high proportions of damaged type I cells within few hours. In fibrosis this capacity also seems to be affected seriously, resulting in transitional phenotypes between type II and type I cells. Additionally, in the light of the detection of CD44 type of adhesion molecules at the foot processes of type II pneumocytes, some aspects of epithelial-fibroblast interaction are described.

Animals↗

PubMed1995

Müller glial cells of the tree shrew retina.

The tree shrew is one of the few mammalian species whose retinae are strongly cone dominated, which is usually the case in reptilian and avian retinae. Müller cells of the tree shrew (Tupaia belangeri) retina were studied by transmission electron microscopy of tissue sections and freeze-fracture replicas, by immunolabeling of the intermediate filament protein vimentin in radial paraffin sections and in whole retinae, as well as by intracellular dye injection in slices of retinae. In addition, enzymatically isolated cells were stained by Pappenheim's panoptic staining method. The cells showed an ultrastructure that is similar to other mammalian Müller cells with two exceptions: Due to the extensive lateral fins of cone inner segments, the apical microvilli of Müller cells are arranged in peculiar palisades, and the basket-like Müller cell sheaths around neuronal somata in both nuclear layers consist of unusual multilayered membrane lamellae. Unlike Müller cells in other mammalian species studied thus far, but similar to reptilian and avian Müller cells, those of tree shrews commonly have two or more vitread processes rather than one main trunk. Müller cell densities range between some 13,000 mm-2 in the periphery and about 20,000 mm-2 in the retinal center. Neuron:(Müller)glial cell ratios were estimated to be 7.9:1 in the center and 6.2:1 in the periphery. For each Müller cell, about 1.5 (cone) photoreceptor cells, four or five interneurons of the inner nuclear layer, and about one cell of the ganglion cell layer were counted. This is a much lower number of neurons per Müller cell than in most other mammals studied.

Animals↗

PubMed1995

Hepatic retinopathy: morphological features of retinal glial (Müller) cells accompanying hepatic failure.

More than 80 years ago, Alzheimer described changes in the brains of patients who had suffered hepatic failure. Astrocytes are primarily affected; their nuclei become swollen, their intermediate filament protein composition is altered and their cytoplasm becomes vacuolated. Cells with these features are called Alzheimer type II astrocytes and these changes have been attributed to the toxic effects of elevated ammonia levels. The present study investigates whether the dominant glia of another part of the central nervous system, the Müller cells of the retina, undergo similar changes. Retinae of patients who had died with symptoms of hepatic failure were processed for histology, histochemistry, and immunocytochemistry. Cell nuclei were measured from brain astrocytes (insula cortex), Müller cells, and retinal bipolar neurons. Hepatic failure resulted in the enlargement of nuclei in astrocytes and Müller cells, and the enhanced expression in Müller cells of glial fibrillary acidic protein, cathepsin D, and the beta-subunit of prolyl 4-hydroxylase (glial-p55). In some retinae, signs of gliosis were also observed. We conclude that increased levels of serum ammonia resulting from hepatic insufficiency cause changes in Müller cells that are similar to those seen in brain astrocytes. We term this condition hepatic retinopathy.

Adult↗

PubMed1995

Intermediate filament typing of the human embryonic and fetal notochord.

In order to characterize human notochordal tissue we investigated notochords from 32 human embryos and fetuses ranging between the 5th and 13th gestational week, using immunohistochemistry to detect intermediate filament proteins cytokeratin, vimentin and desmin, the cytokeratin subtypes 7, 8, 18, 19 and 20, epithelial membrane antigen (EMA), and adhesion molecules pan-cadherin and E-cadherin. Strong immunoreactions could be demonstrated for pan-cytokeratin, but not for desmin or EMA. Staining for pan-cadherin and weak staining for E-cadherin was found on cell membranes of notochordal cells. Also it was demonstrated that notochordal cells of all developmental stages contain the cytokeratins 8, 18 and 19, but not 7 or 20. Some cells in the embryonic notochord also contained some vimentin. Vimentin reactivity increased between the 8th and 13th gestational week parallel to morphological changes leading from an epithelial phenotype to the chorda reticulum which represents a mesenchymal tissue within the intervertebral disc anlagen. This coexpression reflects the epithelial-mesenchymal transformation of the notochord, which also loses E-cadherin expression during later stages. Our findings cannot elucidate a histogenetic germ layer origin of the human notochord but demonstrate its epithelial character. Thus, morphogenetic inductive processes between the human notochord and its surrounding vertebral column anlagen can be classified as epithelial-mesenchymal interactions.

Antibodies, Monoclonal↗

PubMed1995

Distribution of E-cadherin and Ep-CAM in the human lung during development and after injury.

Paraffin sections were obtained of human fetal, adult, and pathological lung (pulmonary fibrosis after radiotherapy or chemotherapy). The localization of epithelial adhesion molecules E-cadherin and Ep-CAM (former epithelial surface 40 kDa glycoprotein) was investigated by immunoperoxidase and/or immunofluorescence techniques with monoclonal antibodies. During development, the epithelia of the primary pulmonary primordium, the secondary bronchi and the adult bronchial epithelium retained immunoreactivity for E-cadherin and Ep-CAM with lateral immunostaining of cell membranes. In normal adult lungs, Ep-CAM was detected in type I and II alveolar epithelial cells, whereas E-cadherin was confined to the basolateral domain of type II cells. In pulmonary fibrosis, Ep-CAM could be further detected on the cell surface of epithelial remnants. In contrast, E-cadherin expression was characterized by a change of the membrane localization to a spotty, cytoplasmic pattern in the alveolar epithelium, possibly indicating functional inactivation of the protein during fibrogenesis.

Adult↗

PubMed1995

Immunocytochemical distribution of E-cadherin in normal and injured lung tissue of the rat.

Affinity purified rabbit anti-mouse E-cadherin antibodies, reacting with diverse rat epithelia, were used to characterize epithelial changes in a radiation-induced fibrosis model of rat lung by immunoblotting techniques, immunoperoxidase and immunofluorescence microscopy. Immunostaining of normal rat lung tissues revealed a predominant staining of type II pneumocytes. Immunoelectron microscopy confirmed the immunohistochemical data of normal lung tissue obtained at the light microscopic level. In severely injured rat lung, we found enhanced immunoreactivity for E-cadherin at the surface of type I alveolar epithelial cells. The results suggest that E-cadherin is an adhesion molecule that is modulated after pathological alteration of the alveolar epithelium and that the antiserum may be useful for the characterization of normal and diseased rat epithelia.

Animals↗

PubMed1995

Immunohistochemical evidence for loss of ICAM-1 by alveolar epithelial cells in pulmonary fibrosis.

ICAM-1 is an intercellular adhesion molecule of the immunoglobulin supergene family involved in adherence of leukocytes to the endothelium and in leukocytic accumulation in pulmonary injury. In the current study, the antigen retrieval technique was used to detect ICAM-1 immunohistochemically in paraffin sections of lungs from human, mouse and rat as well as in bleomycin- or radiation-induced fibrotic lungs from rat and human. In normal lung tissue, the expression of ICAM-1 on alveolar type I epithelial cells is stronger than on alveolar macrophages and on endothelial cells. Preembedding immunoelectron microscopy of normal rat, mouse and human lung samples revealed selective ICAM-1 expression on the surface of type I alveolar epithelial cells and, to a lesser extent, on the pulmonary capillary endothelium and on alveolar macrophages. In fibrotic specimens, both focal lack and strengthening of immunostaining on the surface of type I cells was found. Alveolar macrophages were found focally lacking ICAM-1 immunoreactivity. In some cases, rat type II pneumocytes exhibited positive immunoreactions for ICAM-1. Immunoelectron microscopy with preembedded rat lungs (bleomycin-exposed cases) confirmed the altered ICAM-1 distribution at the alveolar epithelial surface. In the alveolar fluid of fibrotic rat lungs, in contrast to that from untreated controls, soluble ICAM-1 was detected by western blot analysis.

Animals↗

PubMed1995

Secretory group II phospholipase A2 in human atherosclerotic plaques.

Atherosclerotic plaques exhibit a series of features that are similar to those of chronic inflammation. Based on the fact that during inflammation several cell types synthesize and secrete a group II phospholipase A2 (PLA2), an immunohistochemical study was undertaken to explore whether this enzyme can be identified in human atherosclerotic lesions. Tissue specimens obtained from 13 patients who had undergone arteriectomy and three specimens with advanced atherosclerotic plaques obtained at autopsy were analyzed and compared to arteries free of atherosclerosis. The results showed that in all areas with atherosclerotic lesions, a staining with monoclonal antibodies raised against group II PLA2 was evident. In normal arteries without thickened intima, this immunostaining was completely negative. With the use of specific monoclonal antibodies against macrophages (anti-KP-1) and smooth muscle cells (anti-alpha-actin), PLA2-positive cells were identified as foam cells mainly derived from macrophages. In addition to these cells, other regions of the thickened intima gave a partially positive reaction with anti-PLA2 antibodies, but could not be stained with either anti-KP-1 or anti-alpha-actin. Some of these regions were localized on edges of calcification and cell necrosis. Other PLA2-positive regions seem to be associated with extracellular matrix structures. In summary, the findings of this study may be regarded as further evidence to support the link between atherosclerosis and chronic inflammatory processes. In view of the fact that the in vitro modification of lipoproteins by PLA2-treatment induces lipid deposition in macrophages, the results of this study suggest that group II PLA2 may actively be involved in the formation of foam cells in vivo.

Aged↗

PubMed1995

Expression of p53 and bcl-2 in correlation to clinicopathological parameters, hormone receptor status and DNA ploidy in breast cancers.

The expression of p53 and bcl-2 was immunohistochemically investigated in 61 formalin-fixed, paraffin-embedded invasive breast carcinomas. The study was aimed to elucidate the relationship between both markers and the correlation of p53 and bcl-2, respectively, to clinicopathological variables, to hormone receptor status and to DNA-ploidy. Twenty tumors showed a positive reaction with the monoclonal antibody DO-1 against p53 protein. Its immunohistochemical demonstration was significantly correlated with a tumor size larger than 2 cm, a low estrogen receptor status and DNA-aneuploidy. Bcl-2 was demonstrated in 51 breast cancers. Bcl-2 was preferably seen in low grade and hormone receptor positive tumors. We found a negative correlation between the immunoreactive scores of p53 and bcl-2, but in 17 carcinomas a coexpression of both proteins was seen. Cases with this coexpression did not differ significantly from the other tumors in clinicopathological parameters. In eight of these cases more than 10% of the cells were found to be positive for both markers. In four cases we could show many cells to exhibit both markers as it was assessed by an immunofluorescence double labeling technique.

Breast Neoplasms↗