Search PubMed⌕ Search

Biomedical subjects

L Schuger

Publications and source records attributed to L Schuger.

At least 37 records · Page 2Linked to original sources
PubMed1993

Effects of all-trans retinoic acid and Ca++ on human skin in organ culture.

In this study, we have established an organ culture model of human skin and examined the effects of both all-trans retinoic acid (RA) and extracellular Ca++ on the epidermal and dermal components of the organ-cultured skin. Our data show that while organ cultures maintained in serum-free, growth factor-free culture medium containing 0.15 mM Ca++ degenerated rapidly, those treated with concentrations of RA that have been shown previously to stimulate fibroblast and keratinocyte proliferation in monolayer culture (J Invest Dermatol 1989, 93:449; 1990, 94:717; Am J Pathol 1990, 136:1275) demonstrated a healthy appearance for up to 12 days. Degeneration of the control cultures was characterized by separation of the epidermis from the underlying dermis, progressive cell necrosis leading to a complete absence of viable cells from both the dermal and epidermal compartments, disintegration and fibrillation of the dermal connective tissue, and a cessation of protein synthesis. RA-treated organ cultures contained large numbers of healthy-appearing cells in both the epidermal and dermal compartments. One or several layers of viable basal cells in the epidermis could be seen at least through day 12. However, the upper layers of the epidermis frequently separated from the cells in the basal layer. The dermal connective tissue was histologically well-preserved. Furthermore, the level of protein synthesis was higher in the RA-treated cultures than in the control cultures. In addition to treating organ cultures with RA, other cultures were exposed to serum-free, growth factor-free culture medium containing 1.4 mM Ca++. The presence of the elevated Ca++ concentration also preserved cellular and connective tissue structures in the dermal and epidermal compartments. In comparison to RA there was better preservation of the overall epidermal structure. The upper layers of epidermal cells did not separate from the basal cells, and the various stages of epithelial differentiation could be seen. Histologically, the dermis was well-preserved in the presence of elevated extracellular Ca++. Specimens treated with a combination of Ca++ and RA demonstrated features consistent with the features induced by each treatment separately. This included an expanded basal layer of epithelial cells and a prominent keratotic layer with a fairly orderly pattern of differentiation. The tendency of the upper epidermis to separate from the basal cells was partially mitigated. Taken together, these data indicate that both RA and extracellular Ca++ act to prevent the degeneration of human skin in organ culture but probably do so through different mechanisms.

Adult↗
PubMed1992

Laminin expression in the mouse lung increases with development and stimulates spontaneous organotypic rearrangement of mixed lung cells.

The recent establishment of a role for laminin in mouse lung organogenesis (Schuger et al. 1990a,b, 1991) prompted us to study its expression in the developing lung. Laminin A and B chains were detected in the murine lung from the first hours of development onward. In situ hybridization of mRNA as well as SDS-PAGE studies of lung cells in monoculture indicated that both epithelium and mesenchyme produce complete laminin molecules. Quantitative analysis of the in situ hybridization studies showed a gradual increase in laminin expression during development which was further supported by immunohistochemistry and ELISA. The overall pattern of expression suggested that the effects of laminin in morphogenesis were not restricted to a particular stage of development. Furthermore, the increase in expression during late development supported a role for the molecule in the fetal lung, which was not previously established. We next determined whether the increase in laminin production modulated the behavior of fetal lung cells as compared with their embryonic counterparts. We previously showed that organotypic pattern formation does not occur in cultures of mixed embryonic lung cells unless exogenous laminin is added (Schuger et al., 1990b). Organotypic pattern formation is the result of cell sorting into epithelial and mesenchymal compartments and further rearrangement in a pattern resembling the tissue of origin. In the present study, we demonstrated that organotypic pattern formation occurs spontaneously in cultures of mixed fetal lung cells, which express high laminin levels. Pattern formation was abolished by antibodies to laminin. These studies suggest a correlation between laminin expression and the ability of lung cells in culture to reproduce normal tissue patterns. We conclude that laminin is critical for epithelial-mesenchymal recognition and further morphogenic interaction during both the embryonic and fetal stages of lung development.

Animals↗
PubMed1991

Production of fibronectin by human tumor cells and interaction with exogenous fibronectin: comparison of cell lines obtained from colon adenocarcinomas and squamous carcinomas of the upper aerodigestive tract.

Cell lines derived from 13 different human colon adenocarcinomas were examined for production of fibronectin by ELISA and for cell-surface expression of fibronectin by indirect immunofluorescence. Two squamous epithelial cell lines obtained from tumors of the upper aerodigestive tract were used as controls. None of the 13 colon carcinoma lines produced detectable amounts of fibronectin or showed detectable cell-surface staining with anti-fibronectin. The 2 squamous epithelial cell lines, in contrast, produced large amounts of fibronectin which could be detected in the culture medium and bound to the substratum. The squamous carcinoma cells also stained brightly when examined in the viable state by immunofluorescence with anti-fibronectin. In addition to being studied for fibronectin production, each cell line was also examined for the ability to interact with exogenous fibronectin in an adhesion assay. None of the colon carcinoma cells were adherent to fibronectin-coated culture dishes while the 2 squamous carcinoma cells rapidly attached and spread on this substratum. These data suggest that cell lines derived from adenocarcinomas of the colon are deficient in production of fibronectin and in their ability to interact with exogenous fibronectin. In their degree of deficiency, the colon carcinoma cells are significantly different from several different types of human tumor cell. The failure of the colon carcinoma cells to synthesize detectable amounts of fibronectin endogenously or to interact with exogenous fibronectin may explain, in part, the low degree of adhesive interaction which these cells have for their substratum. This, in turn, may influence the in vitro and in vivo properties of colon carcinoma cells.

Adenocarcinoma↗
PubMed1991

Identification of laminin domains involved in branching morphogenesis: effects of anti-laminin monoclonal antibodies on mouse embryonic lung development.

We recently found that polyclonal antibodies to laminin, a basement membrane-related glycoprotein, inhibited murine lung morphogenesis when added to organ cultures of mouse embryonic lung. Using a series of monoclonal anti-laminin antibodies with previously characterized subunit specificity (termed AL-1, AL-2, AL-3, AL-4, and AL-5), the deposition and functional involvement of different laminin domains in the developing lung were investigated. By immunohistochemistry the antibodies' reactivity was largely localized to the basement membrane, but was also present diffusely in the extracellular matrix throughout the mesenchyme. Organ cultures of lung explants from Day 12 embryos were cultured for 3 days in the presence of 50-100 micrograms/ml of each antibody or in the presence of the same concentration of immunoglobulins G and M, laminin-neutralized antibody, or medium alone. Cultures were monitored by phase-contrast microscopy, light microscopy, and immunofluorescence. Although all antibodies penetrated the tissues in culture, only two of them inhibited branching activity. These two antibodies were AL-1, which binds on or near the cross region of laminin, and AL-5, which binds to the lateral short arms at the globular end regions of the B chain of laminin. Inhibition of branching with these two antibodies was dose-dependent and statistically significant for the two concentrations used. AL-2, AL-3, AL-4, laminin-neutralized antibodies and control immunoglobulins did not alter lung morphogenesis. The two domains of laminin that promote lung branching morphogenesis have been reported by others to promote the attachment of a variety of cells and/or bind heparin. These domains of laminin may promote branching morphogenesis by facilitating cell attachment and, consequently, cell proliferation.

Animals↗
PubMed1991

Thrombospondin production and thrombospondin-mediated adhesion in U937 cells.

U937 cells have low levels of surface thrombospondin (TSP) under control conditions but express higher levels after treatment for 1 day with 100 nM phorbol myristate acetate (PMA). Increased surface expression is due, in part, to increased biosynthesis. Untreated U937 cells do not adhere to TSP-coated plastic culture dishes but adhere strongly to TSP after stimulation with PMA. Untreated U937 cells also adhere weakly to endothelial cell monolayers while PMA-treated U937 cells attach strongly to monolayers of rat pulmonary artery endothelial cells. Endothelial cell adhesion appears to be mediated, in part, by TSP since antibodies to TSP partially inhibit.

Animals↗
PubMed1990

Percutaneous transcatheter laser balloon ablation from the canine coronary sinus: implications for the Wolff-Parkinson-White syndrome.

Transcatheter direct current electrical shocks for ablation of left-sided accessory pathways in Wolff-Parkinson-White patients have led to serious complications. We report the feasibility of percutaneous transcatheter laser balloon ablation of left-sided accessory pathways from the coronary sinus using a 1,064-nm, continuous wave Nd:YAG laser triple lumen catheter with an optical fiber terminating in a cylindrical diffusing tip within a 2-cm-long, 3-mm-diameter balloon transparent to Nd:YAG laser radiation. In eight mongrel dogs (18 to 31 kg), the laser balloon catheter was positioned via an 8 French guide catheter in the distal and proximal coronary sinus. During balloon inflation, two to three consecutive laser doses of 30 W x 20 sec were applied to each site (cumulative energy, 1,200 to 1,800 J). Coronary angiography, left ventriculography, and coronary sinus injection were performed before and after laser exposure. After percutaneous transcatheter laser balloon ablation, there was no evidence of mitral regurgitation, left circumflex artery, coronary sinus obstruction, or perforation. Coagulation necrosis and/or polymorphonuclear infiltrates involving the atrioventricular groove and left atrial wall over a mean length of 17 mm were present in all eight dogs sacrificed 6 +/- 1 hr postablation. In conclusion, percutaneous transcatheter laser balloon ablation from the coronary sinus is free of immediate major complications and may be feasible for potential interruption of left-sided accessory pathways.

Animals↗
PubMed1990

Laminin in lung development: effects of anti-laminin antibody in murine lung morphogenesis.

The pattern of deposition and the role of laminin, a major glycoprotein constituent of basement membranes, were investigated during lung morphogenesis in the fetal mouse. Lung primordia were removed from Day 13 embryos, right lower lobes were further dissected and placed in filter membrane assemblies. Explants were then cultured at the liquid-air interface for 3 days in the presence of anti-laminin, anti-thrombospondin (another extracellular matrix constituent), preimmune serum, laminin-neutralized anti-laminin, or medium alone. Cultures were monitored by (direct) phase-contrast microscopy, light microscopy, and immunofluorescence. We found that anti-laminin antibodies altered normal lung morphogenesis in a dose-dependent manner. The anti-laminin-treated explants presented a marked inhibition of branching morphogenesis and a distortion of the bronchial tree. A lower rate of growth was also observed in the explants exposed to this antibody. High concentrations of anti-thrombospondin antibodies, normal rabbit serum, or laminin-neutralized anti-laminin antibodies had no effect on lung morphogenesis. These results were not modified by culturing the explants in submersion culture or on Vitrogen 100-coated surfaces.

Animals↗
PubMed1990

Modulation of squamous carcinoma cell growth, morphology, adhesiveness and extracellular matrix production by interferon-gamma and tumor necrosis factor-alpha.

Interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) were examined for effects on human squamous carcinoma cells. IFN-gamma inhibited proliferation at concentrations between 100 and 1,500 units/ml and the inhibitory effects were potentiated by TNF-alpha. Inhibition of cell growth was not accompanied by cytotoxicity. Combined treatment with the two cytokines also inhibited cell-substrate adhesion and altered the morphology of the cells. The treated cells were large and flattened. These morphological features are similar to those that have been previously described for normal keratinocytes induced to differentiate by a variety of means. The changes in biological properties were accompanied by alterations in production of extracellular matrix components - e.g., fibronectin and thrombospondin. Synthesis of both components was decreased following treatment. The cytokine-induced alterations in squamous carcinoma cell properties were fully reversible. These findings indicate that malignant squamous epithelial cells may be similar to their normal counterparts in their responses to IFN-gamma and TNF-alpha. In the malignant cells, however, these cytokines do not appear to induce permanent phenotypic changes.

Carcinoma, Squamous Cell↗
PubMed1990

Organotypic arrangement of mouse embryonic lung cells on a basement membrane extract: involvement of laminin.

The behavior of embryonic murine lung cells on a basement membrane extract (Matrigel) was investigated. Single cell suspensions generated by trypsinization of lungs removed from day 12 embryos were plated on Matrigel and cultured for up to one week. The basement membrane extract was used as a gel, and as a wet or dried film. In all of these instances, organotypic arrangement of the embryonic lung cells was observed. This process consisted of cell aggregation, sorting, polarization and formation of a tridimensional organization resembling embryonic lung. The maximal degree of organotypic development was obtained by using a thick gel; minimal reorganization was observed using a dried film. A rabbit polyclonal serum to laminin inhibited organotypic pattern formation while normal rabbit serum did not. Culture of lung cells on laminin gels promoted epithelial cyst formation but poor mesenchymal organization. By studying the behavior of epithelial and/or mesenchymal enriched cell populations on Matrigel, it was concluded that organotypic pattern formation on Matrigel required the presence of both cell populations. Cultivation of dissociated lung cells on a gel consisting of a mixture of collagens type I and III (Vitrogen-100) produced only cell aggregation. Cultivation of lung cells on a thin film of Vitrogen-100 or on uncoated tissue culture plastic produced monolayers of mesenchymal cells alone. Cultivation of lung cells in suspension also failed to induce organotypic arrangement even at maximal cell densities. The present study strongly supports a role for the basement membrane in the organotypic rearrangement of embryonic lung cells and subsequent in vitro cyst formation and budding of the reestablished epithelium. This, in turn, reinforces the concept of the basement membrane as a major regulator of organogenesis.

Animals↗
PubMed1989

Vascular endothelial cell killing by combinations of membrane-active agents and hydrogen peroxide.

Previous studies have demonstrated that a number of membrane-active agents are capable of binding to the surface of polymorphonuclear leukocytes (PMN) resulting in an augmentation of superoxide anion and hydrogen peroxide (H2O2) production in response to soluble stimuli. It is now demonstrated that these same membrane-active agents can bind to the surface of endothelial cells and enhance their susceptibility to killing by H2O2. Membrane-active agents which are capable of synergizing with H2O2 include cationic proteins, cationic poly-amino acids, lysophosphatides and enzymes which are capable of degrading membrane phospholipids (e.g., phospholipase C, phospholipase A2 and streptolysin S). In each case, treatment of the target cells with the membrane-active agent and H2O2 produces greater damage than the sum of the damage produced by either agent separately. Since inflammatory lesions, particularly sites of bacterial infection, may contain a rich mixture of cationic substances, phospholipases and phospholipid breakdown products, these substances may contribute to the tissue damage observed at sites of inflammation by enhancing endothelial cell sensitivity to PMN-generated H2O2 as well as by augmenting the generation of H2O2 by PMNs.

Animals↗
PubMed1989

The etiology of tumor plop in a patient with huge right atrial myxoma.

In a patient with a large atrial myxoma, the phonocardiographic timing of the tumor plop has been correlated with the two-dimensional echocardiographic motion pattern of the cardiac mass. The tumor plop occurred at the time when the mass stopped its diastolic forward motion into the ventricle and made a strong impact on the interventricular septum and right ventricular posterior wall. Occurrence of tumor plop may require a large mass or long enough tumor stalk to allow the impact of the mass on the ventricular wall.

Adult↗
PubMed1989

Endothelial cell killing by neutrophils. Synergistic interaction of oxygen products and proteases.

Killing of rat pulmonary artery endothelial cells by activated polymorphonuclear leukocytes (PMNs), as measured at 4 hours, is catalase sensitive, iron dependent, and unaffected by addition of protease inhibitors. If the time course for exposure of endothelial cells to activated PMNs is extended to 18 hours, progressive injury occurs. Endothelial cell injury resulting at 18 hours is partially inhibited by catalase and partially inhibited by soybean trypsin inhibitor. Together, these two inhibitors function synergistically to protect the cells from injury. Exposure of endothelial cells to reagent H2O2 and purified proteolytic enzymes (trypsin, chymotrypsin, elastase, and cathepsin G) mimics the effects of activated PMNs: H2O2 alone is cytotoxic with maximal killing achieved by 4 hours; proteolytic enzymes produce cytotoxicity only at high concentrations and only after prolonged incubation (longer than 8 hours); and, in combination, H2O2 and proteolytic enzymes act synergistically. These data provide compelling evidence that PMN-mediated injury of endothelial cells involves interaction between oxygen products and proteases.

Adult↗
PubMed1989

Cytotoxicity of tumor necrosis factor-alpha for human umbilical vein endothelial cells.

Human umbilical vein endothelial cells were examined for sensitivity to killing by human recombinant tumor necrosis factor-alpha (TNF-alpha). Treatment of the cells with concentrations of TNF-alpha up to 50 ng/ml for 18 hours did not produce evidence of cytotoxicity. However, a marked cytotoxic effect was found when TNF-alpha pretreated cells were incubated in Hanks' balanced salt solution for a further 4 hours. Exposure of the cells to heat-inactivated or antibody-neutralized TNF-alpha did not result in cytotoxicity. Human recombinant interleukin-1 also lysed endothelial cells under the same conditions, whereas human recombinant macrophage-colony stimulating factor did not. Inclusion of superoxide dismutase, catalase, or soybean trypsin inhibitor in the culture medium during the time of endothelial cell exposure to TNF-alpha had no protective effects. Likewise, allopurinol (a xanthine oxidase inhibitor) and nordihydro-guaiaretic acid (a lipoxygenase inhibitor) were not protective under the same conditions. In contrast, the ferric iron chelator deferoxamine mesylate and three different cyclooxygenase inhibitors provided significant protection against TNF-alpha induced cytotoxicity. When human dermal fibroblasts and human squamous epithelial cells were used in place of the umbilical vein endothelial cells, these cells were resistant to TNF-alpha mediated killing. These findings demonstrate that under the experimental conditions employed, TNF-alpha is cytotoxic for human umbilical vein endothelial cells. This may have implications in a number of in vivo situations in which TNF-alpha is thought to play a role.

Cell Survival↗
PubMed1988

Duodenal epithelial atypia. A specific complication of hepatic arterial infusion chemotherapy.

Severe duodenal lesions developed in five patients during hepatic arterial infusion (HAI) employing 5-floxuridine (FUDR) as the basic antineoplastic agent. These lesions comprised ulcerative as well as proliferative processes. Striking structural distortion with cellular pleomorphism of the affected duodenal mucosa were the histological hallmark in all cases. These lesions are a specific complication of HAI chemotherapy and should not be misinterpreted as malignancy.

Adult↗
PubMed1988

Comparative morphology and tumourigenicity of human hepatocellular carcinoma cell lines in athymic rats and mice.

Four human hepatoma cell lines PLC/PRF/5, Hep G2, Sk-Hep 1 and Mahlavu were inoculated subcutaneously into athymic Balb/c nude mice and N/NIH outbred nude rats, producing well encapsulated tumours. The 4 hepatoma tumour types in the athymic rodents differ morphologically. PLC/PRF/5 and Hep G2 cells are well differentiated polygonal cells which resemble normal hepatocytes. Tumour arrangement is characterized by solid masses and trabeculae while stromal support is minimal. In contrast, Mahlavu and Sk-Hep 1 tumours have a sarcomatous appearance and consist of spindle shaped cells arranged in solid masses with a rich stromal support. Tumourigenicity of hepatoma cells in the athymic rodents was dependent on injected cell type, inoculation density, relative immunocompetence of the host and the species of animals used. In nude mice, Sk-Hep 1 cells were the most tumourigenic, while Hep G2 cells were tumourigenic only at very high inoculation densities. In nude rats, which were more resistant to tumour formation, PLC/PRF/5 cells were the most tumourigenic. Pre-treatment of athymic mice and rats with total body irradiation resulted in enhanced tumourigenicity for all hepatoma cell lines tested. This was manifested as increased "take" rates, a decreased latency from tumour cell injection to tumour detection, increased tumour weight, and for PLC/PRF/5 cells an increased invasiveness to adjacent body cavities. Furthermore, following irradiation, the minimal number of injected cells required to produce subcutaneous tumours was markedly reduced in both animal species, regardless of tumour cell type. The protocols described enable the reproducible growth of human hepatoma tumours in athymic rodents.

Animals↗
PubMed1988

Delta virus infection in Jerusalem.

The role of hepatitis delta virus (HDV) infection was analyzed retrospectively in a highly selected population of 76 patients who were hospitalized in Jerusalem for hepatitis B surface antigen positive for chronic active hepatitis and cirrhosis. Of 25 patients in whom serum and liver tissue were available, 5 patients (20%) showed evidence for HDV infection using a serum anti-HDV IgG radioimmunoassay; in one of them, HDV was also detected in nuclei of infected hepatocytes by immunofluorescence (IF). When only serum was tested, 12 of 45 patients (27%) were anti-HDV IgG positive. The use of IF alone had a very low yield of HDV detection. All HDV-positive patients with available serum had superinfection with the delta agent as confirmed by a negative anti-HBc IgM assay. The majority of HDV-positive patients were immigrants from Rumanian or Middle Eastern and Mediterranean origin. The mean age of delta-positive patients was 10 years lower at clinical presentation as compared with HDV-negative patients. HDV-positive patients had a higher mortality as compared with the HDV-negative group. In conclusion, HDV infection is prevalent among Israeli patients with chronic liver disease and persistent hepatitis B virus infection and leads to a significant morbidity and mortality.

Adolescent↗
PubMed1987

Cardiac myxoma. A retrospective immunohistochemical study.

Seven cardiac myxomas were studied by immunoperoxidase and immunofluorescence in formalin fixed and paraffin embedded tissues. Specific antisera to factor VIII related antigens, vimentin, myosin of smooth muscle, actin, desmin, alpha-1-antitrypsin, muramidase, fibrin and prekeratin antigens were used. All myxoma cells reacted positively with antibodies to vimentin and showed no staining reaction with antibodies to alpha-1-antitrypsin, muramidase, myosin, or prekeratin. Factor VIII related antigen was found only in endothelial cells and not in myxoma cells proper. Fibrin was found in patchy areas within the stroma. Antisera to actin and desmin failed to react with formalin fixed tissue. Our results suggest that the main cellular component of cardiac myxoma is a primitive mesenchymal cell without immunohistochemical evidence of more specific differentiation.

Actins↗