PubMed Health⌕ Search

Biomedical subjects

R Auerbach

Publications and source records attributed to R Auerbach.

At least 19 recordsLinked to original sources
PubMed1992

Interaction of endothelial cells with a laminin A chain peptide (SIKVAV) in vitro and induction of angiogenic behavior in vivo.

Endothelial cells are known to bind to laminin, and two peptides derived from the laminin A (CTFALRGDNP) and B1 (CDPGYIGSR) chains block the capillary-like tube formation on a laminin-rich basement membrane matrix, Matrigel. In the present study, we have used various in vitro and in vivo assays to investigate the angiogenic-biologic effects of a third active site in the laminin A chain, CSRARKQAASIKVAVSADR (designated PA22-2) on endothelial cells. The SIKVAV-containing peptide was as active as the YIGSR-containing peptide for endothelial cell attachment but was less active than either the RGD-containing peptide or intact laminin. Endothelial cells seeded on this peptide appeared fibroblastic with many extended processes, unlike the normal cobblestone morphology observed on tissue culture plastic. In addition, in contrast to normal tube formation on Matrigel, short irregular structures formed, some of which penetrated the matrix and sprouting was more apparent. Analysis of endothelial cell conditioned media of cells cultured in the presence of this peptide indicated degradation of the Matrigel and zymograms demonstrated active collagenase IV (gelatinase) at 68 and 62 Kd. A murine in vivo angiogenesis assay and the chick yolk sac/chorioallantoic membrane assays with the peptide demonstrated increased endothelial cell mobilization, capillary branching, and vessel formation. These data suggest that the -SIKVAV-site may play an important role in initiating branching and formation of new capillaries from the parent vessels, a behavior that is observed in vivo in response to tumor growth or in the normal vascular response to injury.

Amino Acid Sequence↗
PubMed1992

[The heterogenicity of the vascular endothelium].

The vascular endothelium has long been considered to be a homogeneous cell type. It is only recently that its remarkable heterogeneity has been shown. The selective and organ-specific adhesion of cells of the immune system, of metastasizing tumor cells and of microorganisms underscores the central position of the endothelium between the circulation and each organ. The use of antibodies and lectins led to the recognition of species-, organ-, and age-specific endothelial cell surface receptors. Identification of the endothelial adhesion molecules and -mechanisms, which are part of the "endothelial organ- and tissue address" would lead to the possibility of blocking the adhesion of cells, such as e.g. tumor cells.

Animals↗
PubMed1992

Defects in thymocyte differentiation and thymocyte-stromal interactions in the trisomy 16 mouse.

We have examined fetal thymic development in the trisomy 16 (Ts16) mouse, which is considered to be a model for human trisomy 21, or Down Syndrome. The Ts16 thymus contains 10 to 20% of the number of lymphocytes found in a normal thymus at a comparable stage. Expression of thymocyte differentiation markers (Thy-1, CD5, CD8, CD4, CD3, and HSA) is severely affected in Ts16 fetuses aged 14-18 gestational days. When thymuses from 14-day Ts16 mice were cultured in vitro, these markers eventually reached levels of expression comparable to those seen in normal thymuses in culture. On the other hand, expression of CD44 appears to be unaffected in Ts16 thymuses in vivo, but declines in vitro relative to normal thymuses. Reconstitution of depleted thymic stroma with thymocytes showed evidence of defects in both developmental compartments.

Animals↗
PubMed1992

An immune model of beryllium-induced pulmonary granulomata in mice. Histopathology, immune reactivity, and flow-cytometric analysis of bronchoalveolar lavage-derived cells.

BACKGROUND: Beryllium compounds can cause acute and chronic lung injury in humans. Although models of chronic granulomatous lung disease have been established in various animal species, a murine model of beryllium-induced chronic lung disease has not been established. EXPERIMENTAL DESIGN: Beryllium was introduced intratracheally either as a soluble salt (BeSO4) or in particulate form (BeO). Various preimmunization protocols were used to enhance immune-mediated pulmonary changes. Cells obtained by bronchoalveolar lavage (BAL) were analyzed using flow cytometry, and the observations correlated with in vitro immune responses and with lung histopathology. RESULTS: Histologic changes were consistently found in mice preimmunized with BeSO4.4H2O plus syngeneic serum. Addition of complete or incomplete Freund's adjuvant to the preimmunization protocol was not necessary to induce granulomatous changes. BAL showed a significant increase in lymphocytes at 2, 4, and 8 weeks after intratracheal BeSO4. Approximately one-third of BAL lymphocytes expressed the gamma/delta T lymphocyte receptor at 2 weeks; at 4 weeks the lymphocytes were predominantly Thy1+, L3T4+ (CD4+) and expressed only the alpha/beta T lymphocyte receptor. Only BAL lymphocytes from mice preimmunized with BeSO4/serum and challenged with BeSO4/serum showed significant in vitro proliferation in response to BeSO4. Macrophage activation antigens (Mac-2, Mac-3) were expressed only during the acute inflammatory phase (2 weeks) whereas increased expression of a monocyte/macrophage antigen (Mac-1) remained elevated beyond the inflammatory period in some instances. Attempts to induce similar lesions in BALB/c and C57BL6/J mice were unsuccessful. Genetic differences at the H-2 major histocompatibility complex gene complex may account for the differential responses to BeSO4 among various mouse strains. A single exposure to BeO also induced histopathologic changes in the lung which correlated with BAL cellularity, but these changes were only observed 8 months after exposure and did not proceed to frank granulomas. CONCLUSIONS: A murine model of granulomatous lung disease may prove useful in understanding the genetic and immunologic factors that determine the response to beryllium. The animal model may also have implications for pulmonary sarcoidosis, a disease of unknown cause(s), whose disease manifestations and BAL profiles are difficult to distinguish clinically and pathologically from chronic beryllium disease.

Animals↗
PubMed1992

Inhibitory effects of cytokines on vascular endothelial cells: synergistic interactions among interferon-gamma, tumor necrosis factor-alpha, and interleukin-1.

The formation of new blood vessels is critical to tumor growth and metastasis and since endothelial cells are the principal cell type comprising such blood vessels, we carried out experiments to test whether the growth of endothelial cells in vitro can be inhibited by low doses of combinations of cytokines. We show that growth of mouse aortic endothelial cells can be inhibited in vitro by combinations of cytokines that, administered singly even at ten times higher concentrations, have only marginal effects. In particular, interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma), acting synergistically at low, subthreshold concentrations, are able to completely inhibit the growth of endothelial cells in vitro.

Animals↗
PubMed1991

Ontogeny of murine T cells: thymus-regulated development of T cell receptor-bearing cells derived from embryonic yolk sac.

Pre-thymic stem cells which arise extrinsically to the thymus differentiate into mature T cells after colonizing the fetal thymus, but the origin of the stem cells during mammalian embryogenesis remains unknown. More than one potential site has been proposed, including the liver, the omentum and the embryonic yolk sac (YS). Since the murine YS appears earliest in gestation and is the first site of hematopoiesis, our studies focus on the mouse YS as the early major source of pre-thymic stem cells. Previous studies showed that freshly obtained YS cells expressing no known major T cell marker can develop into Thy-1+ cells in vitro either transiently or stably. However, the critical steps leading to functional maturation of T cells involve the rearrangement and expression of the T cell receptor (TcR) genes. We report here that YS cells grown in short-term cell culture show no detectable rearrangement or transcription at the TcR gamma gene locus, although the TcR gamma gene of in vitro transformed YS cells rearranges in the absence of the thymus. However, after seeding lymphocyte-depleted thymuses in vitro, YS cells can differentiate into various subsets of cells appearing in the thymus, including CD3/TcR alpha/beta- and gamma/delta-bearing cells. TcR V gamma 3 which is expressed mainly on early fetal thymocytes and on Thy-1+ dendritic cells can be detected on YS-derived cells. TcR V beta 8-expressing cells which appear later in thymic ontogeny are also detected. The kinetics for reconstituting the thymus varies among YS cells of different ages (day 10 to 13 gestation). These results indicate that a single wave of early mouse YS cells can undergo the molecular and cellular changes associated with T cell differentiation and acquire mature T cell characteristics in the absence of continuous inflow of other stem cells. The thymus acts in an inductive/regulatory role for that differentiation.

Animals↗
PubMed1991

Assays for angiogenesis: a review.

Accurate, reliable quantitation of the neovascular (angiogenic) response, both in vitro and in vivo, is an essential requirement for the study of new blood vessel growth. Over many years, ingenious ways have been developed for measuring this process, and they have contributed much to our present understanding of the vasculogenesis and angiogenesis that accompany normal embryonic development, lactation and wound healing, as well as tumor growth and a variety of other disease states ranging from diabetic retinopathy to autoimmune vasculitis. In this review we describe and evaluate the methodology and specific features of some of the most frequently used of these assays.

Animals↗
PubMed1991

Isolation and characterization of carotenoid hyperproducing mutants of yeast by flow cytometry and cell sorting.

The carotenoid pigment astaxanthin (3,3'-dihydroxy-beta,beta-carotene-4,4'-dione) is an important component in feeds of aquacultural animals. It is produced as a secondary metabolite by the yeast Phaffia rhodozyma, and the isolation of rare mutants that produce increased quantities is limited by the lack of genetic selections. As a model system for enriching mutants increased in production of secondary metabolites, we have used quantitative flow cytometry/cell sorting (FCCS) to isolate astaxanthin hyperproducing mutants of the yeast. Experimental conditions were developed that gave a quantitative correlation of fluorescence and carotenoid content. In mutated populations, a 10,000-fold enrichment of carotenoid-overproducing yeasts was obtained. Distinctive differences were detected by FCCS in fluorescence and forward scatter values of mutant and wild-type populations of yeasts. Comparison of wild-type and mutant clones by fluorescence confocal laser microscopy showed that the mutants had more intense fluorescence throughout the cell than the wild-type. Quantitative FCCS is a sensitive method to isolate and characterize carotenoid overproducing mutants and should be useful as a general method for the isolation of mutants increased in other fluorescent metabolites.

Carotenoids↗
PubMed1991

A VCAM-like adhesion molecule on murine bone marrow stromal cells mediates binding of lymphocyte precursors in culture.

Two new mAbs (M/K-1 and M/K-2) define an adhesion molecule expressed on stromal cell clones derived from murine bone marrow. The protein is similar in size to a human endothelial cell adhesion molecule known as VCAM-1 or INCAM110. VCAM-1 is expressed on endothelial cells in inflammatory sites and recognized by the integrin VLA-4 expressed on lymphocytes and monocytes. The new stromal cell molecule is a candidate ligand for the VLA-4 expressed on immature B lineage lymphocytes and a possible homologue of human VCAM-1. We now report additional similarities in the distribution, structure, and function of these proteins. The M/K antibodies detected large cells in normal bone marrow, as well as rare cells in other tissues. The antigen was constitutively expressed and functioned as a cell adhesion molecule on cultured murine endothelial cells. It correlated with the presence of mRNA which hybridized to a human VCAM-1 cDNA probe. Partial NH2 terminal amino acid sequencing of the murine protein revealed similarities to VCAM-1 and attachment of human lymphoma cells to murine endothelial cell lines was inhibited by the M/K antibodies. All of these observations suggest that the murine and human cell adhesion proteins may be related. The antibodies selectively interfered with B lymphocyte formation when included in long term bone marrow cultures. Moreover, they caused rapid detachment of lymphocytes from the adherent layer when added to preestablished cultures. The VCAM-like cell adhesion molecule on stromal cells and VLA-4 on lymphocyte precursors may both be important for B lymphocyte formation.

Amino Acid Sequence↗
PubMed1991

In vitro development of murine T cells from prethymic and preliver embryonic yolk sac hematopoietic stem cells.

Mature T cells are derived from prethymic stem cells, which arise at one or more extrathymic sites and enter and differentiate in the thymus. The nature of these prethymic stem cells is a critical factor for the formation of the T-cell repertoire. Although the bone marrow of adult mice can provide such stem cells, their origin during murine embryogenesis is still undetermined. Among potential sites for these progenitor cells are the fetal liver and the embryonic yolk sac. Our studies focus on the yolk sac, both because the yolk sac appears earlier than any other proposed site, and because the mammalian yolk sac is the first site of hematopoiesis. Although it has been shown that the yolk sac in midgestation contains stem cells that can enter the thymic rudiment and differentiate toward T-cell lineage, our aim was to analyze the developmental potential of cells in the yolk sac from earlier stages, prior to the formation of the liver and any other internal organ. We show here that the yolk sac from 8- and 9-day embryos (2-9 and 13-19 somites, respectively) can reconstitute alymphoid congenic fetal thymuses and acquire mature T-cell-specific characteristics. Specifically, thymocytes derived from the early embryonic yolk sac can progress to the expression of mature T lymphocyte markers including CD3/T-cell receptor (TCR), CD4 and CD8. In contrast, we have been unable to document the presence of stem cells within the embryo itself at these early stages. These results support the hypothesis that the stem cells capable of populating the thymic rudiment originate in the yolk sac, and that their presence as early as at the 2- to 9-somite stage may indicate that prethymic stem cells found elsewhere in the embryo at later times may have been derived by migration from this extra-embryonic site. Our experimental design does not exclude the possibility of multiple origins of prethymic stem cells of which the yolk sac may provide the first wave of stem cells in addition to other later waves of cells.

Animals↗
PubMed1991

Histologic evaluation of nail clippings for diagnosing onychomycosis.

Nail clippings from patients suspected of having onychomycosis were processed for histologic evaluation in the same manner as routine skin with the addition of a chitin-softening solution prior to processing. The sections were stained by the periodic acid-Schiff method and examined for fungal hyphae. The results were compared with the results of fungal cultures from the same nail. Our findings indicate that routine histopathologic analysis of the nail plate alone is a useful complementary method to fungal culture for diagnosing onychomycosis.

Diagnosis, Differential↗
PubMed1990

A hemangioendothelioma-derived cell line: its use as a model for the study of endothelial cell biology.

The purpose of our research was to develop a stable murine cell line that could serve as a general model for the study of microvascular endothelial cells. To do so we have characterized an endothelial cell line originally derived from a mouse hemangioendothelioma. Endothelioma cells synthesize angiotensin-converting enzyme, express surface receptors for acetylated low density lipoprotein, produce thrombospondin and show intracellular staining with an antibody to von Willebrand antigen. The response of endothelioma cells to endothelial cell mitogens, known angiogenesis-inducing factors, extracellular matrix substrate (Matrigel), and various cytokines was measured. Endothelioma cells show an increased proliferative response to extracts from hypothalamus but only marginally to recombinant fibroblast growth factor or purified endothelial cell growth factor. Rearrangement of cells forming tube-like connections were induced by Matrigel. The chemokinetic responses generally correlated with angiogenesis-inducing properties of the test substances. The results support the conclusion that the endothelioma cell line maintains characteristic endothelial cell properties and behaves in vitro in a manner similar to microvascular endothelial cells.

Animals↗
PubMed1989

Studies of bronchoalveolar lavage cells and fluids in pulmonary sarcoidosis. I. Enhanced capacity of bronchoalveolar lavage cells from patients with pulmonary sarcoidosis to induce angiogenesis in vivo.

Both allogeneic immunocompetent CD4+ lymphocytes and activated macrophages of mice can induce neovascularization when inoculated intradermally into host animals. Because sarcoidosis is associated with an increase in both activated macrophages and CD4+ effector lymphocytes in the lung, we carried out experiments in which cells obtained by bronchoalveolar lavage (BAL) of patients with pulmonary sarcoidosis were tested in a murine intradermal angiogenesis assay. BAL cells from patients with pulmonary sarcoidosis induced a significantly greater degree of angiogenesis than those from normal volunteers or from patients with other lung diseases. Moreover, the degree of angiogenesis induced by BAL cells from patients with sarcoidosis correlated positively with the severity of the disease. When BAL cells were separated into macrophage and lymphocyte subpopulations by flow cytometric techniques, the observed angiogenic activity was restricted primarily or exclusively to macrophages; lymphocytes were unable to induce angiogenesis in this xenogeneic assay system. These experiments suggest that pulmonary macrophages may play a role in the pathogenesis of sarcoidosis by inducing changes in the pulmonary microvasculature. Moreover, we hypothesize that these vascular changes may be induced not only in the lung but also in other organ systems such as skin, muscle, and eye in which microangiopathies are associated with sarcoid disease.

Animals↗