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Biomedical subjects

R Eisenstein

Publications and source records attributed to R Eisenstein.

At least 19 recordsLinked to original sources
PubMed1996

Complement proteins are present in developing endochondral bone and may mediate cartilage cell death and vascularization.

Normal endochondral bone formation follows a temporal sequence: immature or resting chondrocytes move away from the resting zone, proliferate, flatten, become arranged into columns, and finally become hypertrophic, disintegrate, and are replaced by bone. The mechanisms that guide this process are incompletely understood, but they include programmed cell death, a stage important in development and some disease processes. Using immunofluorescence we have studied the distribution of various complement proteins to examine the hypothesis that this sequence of events, particularly cell disintegration and matrix dissolution, are complement mediated. The results of these studies show that complement proteins C3 and Factor B are distributed uniformly in the resting and proliferating zones. Properdin is localized in the resting and hypertrophic zone but not in the proliferating zone. Complement proteins C5 and C9 are localized exclusively in the hypertrophic zones. This anatomically segregated pattern of distribution suggests that complement proteins may be important in cartilage-bone transformation and that the alternate pathway is involved.

Animals↗
PubMed1991

Angiogenesis in arteries: review.

The inner parts of the walls of large blood vessels do not normally contain intrinsic vasculature. In pathologic conditions such as arteriosclerosis or thrombosis, angiogenesis occurs, and may have significant clinical consequences. This review attempts to relate the little that is known about the factors specific to vascular walls which regulate angiogenesis to more general knowledge of the phenomenon.

Animals↗
PubMed1991

Growth inhibitory activities in avascular tissues are recognized by anti-transforming growth factor beta antibodies.

The aqueous and vitreous humors are normally avascular and may be sites of altered inflammatory responses. Inhibitors of endothelial cell and lymphocyte growth as well as of angiogenesis have been isolated from vitreous and an inhibitor of lymphocyte mitogenesis has been found in aqueous. Data are presented here indicating that aqueous humor also inhibits endothelial cell growth. In addition, neutralizing antibodies against TGF beta block the effects of materials isolated from these tissues on endothelial cell and lymphocyte growth. Similar data were obtained from aorta, another normally avascular site. These observations suggest that the avascularity and altered inflammatory responses in these sites may be regulated in part by TGF beta.

Animals↗
PubMed1989

Synthetic peptides of the amino-terminus of fibronectin inhibit endothelial cell growth.

Amino-terminal and carboxyl-terminal fragments of human plasma fibronectin, at nM concentrations, reversibly inhibit the growth of cultured bovine aortic endothelial cells. To define smaller active peptides, synthetic peptides corresponding to a carboxyl-terminal disulfide bonded loop segment of one of the fragments were tested for activity and found to be active at microM concentrations. The data suggest that the entire loop sequence is required for full expression of endothelial cell growth inhibitory activity in vitro.

Amino Acid Sequence↗
PubMed1988

Isolation and partial characterization of neutrophil elastase inhibitors from bovine vitreous and aorta.

Bovine vitreous body and aorta contain extractable leukocyte elastase inhibitors, which were purified by gel filtration and affinity chromatography on agarose-pancreatic elastase. The purified inhibitor preparation from aorta was resolved by polyacrylamide gel electrophoresis into a main band migrating slightly faster than commercial Trasylol and a more weakly stained band migrating close to chymotrypsinogen. The purified inhibitor preparation from both sources inhibited, in a competitive fashion, purified human leukocyte elastase and was ineffective against bovine trypsin and leukocyte cathepsin G or collagenase. These inhibitors from vitreous body and aorta were distinguishable by several criteria from serum inhibitors.

Animals↗
PubMed1986

Heparin-binding fragments of fibronectin are potent inhibitors of endothelial cell growth: structure-function correlations.

Heparin-binding fragments derived from the amino- and carboxyl-terminal regions of human plasma fibronectin appear to be at least relatively specific potent inhibitors of the growth of bovine aortic endothelial cells in culture by as yet unknown mechanisms. In order to understand better the sites which subserve this activity, we have compared the relative potency of other major fragments of fibronectin, most of which have dissimilar properties and do not bind heparin. We have also proteolytically digested and chemically modified the most potent of these fragments, the amino-terminal 29-kDa fragment, in order to test whether structural alterations that affect heparin-binding also affect the inhibitory property. Not all chemical modifications that abolished heparin-binding also abolished endothelial cell growth. Neither an amino-terminal 20-kDa nor a carboxyl-terminal 8-kDa subfragment of the 29-kDa fragment bound heparin; however, both were as inhibitory as native 29-kDa fragment. Reduction of the disulfides of the 20-kDa and 8-kDa fragments did not abolish inhibitory activity. We therefore conclude that the activity is not strictly conformation-dependent and that although the inhibitory activity is distributed throughout the 29-kDa segment, it can be expressed by an 8-kDa carboxyl-terminal segment containing residues of the last Type I loop structure.

Cells, Cultured↗
PubMed1985

Additive cytotoxicity of adriamycin and a naturally occurring growth inhibitor extracted from bovine aorta.

A factor of nominal molecular weight 6K-10K Daltons, isolated from bovine aorta, has previously been shown to inhibit neovascularization and tumor growth in vivo and the growth of some tumor cells as well as endothelial cells in culture. This factor, termed A-10, was tested alone and in combination with Adriamycin against TA3Ha mammary adenocarcinoma cells in tissue culture. It was found to have cytotoxicity additive to that of Adriamycin in inhibiting the growth of these cells. In vitro and animal studies show that the sequence of Adriamycin----A-10 is superior to either agent alone in delaying the appearance of palpable tumors after subcutaneous injection of 10(5) pre-treated tumor cells in the tail of strain A mice. While the growth rate of the primary tumor was not affected by such treatment, survival was prolonged to a greater degree by the this sequence than by either of these agents used alone. A-10 treatment reduced the number of metastases to the adrenal gland but not to lung, liver, or lymph nodes. It did, however, reduce the size of metastases to para-aortic lymph nodes.

Animals↗
PubMed1985

Inhibition of collagenase activity by extracts of bovine ocular tissues.

Bovine eyes were dissected and separate pools of lens, lens capsule, cornea and vitreous were extracted in guanidine, subjected to ultrafiltration, and examined for their effects on collagenolytic activity. Although lens extract was not inhibitory, the cornea and vitreous both contained inhibitors of collagenase. More inhibition was present in the filtrate of the vitreous than in the retentate, whereas the total amount of inhibition in the cornea was distributed almost equally between the two fractions. The inhibition observed was dose dependent. The partially purified inhibitors from cornea and vitreous blocked the activity of human skin and tadpole back skin collagenases, but they failed to inhibit the bacterial (Clostridium histolyticum) collagenase. The inhibitor was stable to heating to 60 degrees for 30 minutes and to trypsinization.

Animals↗
PubMed1985

Ocular tissues contain inhibitors of lymphocyte mitogenesis.

A fraction of bovine vitreous extract is a potent inhibitor of mitogen induced lymphocyte proliferation in vitro. Proliferation of lymphocytes induced in culture by lipopolysaccharide was more sensitive to inhibition by this fraction than were cultures of lymphocytes stimulated by Concanavalin A. We were unable to demonstrate such activity in similarly prepared fractions of cornea and lens.

Animals↗
PubMed1985

Heparin-binding fragments of fibronectin are potent inhibitors of endothelial cell growth.

Two heparin-binding proteolytic fragments of fibronectin--an amino-terminal 29-kd segment and a carboxyl-terminal 40-kd segment-are apparently specific, potent inhibitors of the growth of cultured bovine aortic endothelial cells and inhibit growth in a reversible, dose-dependent manner. In contrast, native fibronectin at higher dosages neither inhibits nor interferes with the effects of the 29-kd fragment. The data, therefore, suggest that fibronectin fragments may participate in the regulation of vascular growth.

Animals↗
PubMed1984

Inhibitor of vascular endothelial cell growth in the lens.

Because diabetic eyes with proliferative retinopathy show an increased incidence of iris neovascularization after removal of the lens, we studied the effect of extracts of human and bovine lenses on one of the key events in the neovascular process, endothelial cell proliferation. Both human and bovine lens extracts demonstrated a dose-dependent inhibition of bovine aorta endothelial cell proliferation that was greatest in extracts with molecular weight of less than 100,000. This inhibition was reversible and the extracts did not significantly inhibit smooth muscle cell proliferation. Considerable endothelial cell inhibitory activity was present in bovine lens capsule extracts. These data suggested that the lens may play an active role in the prevention of iris neovascularization.

Angiogenesis Inducing Agents↗
PubMed1984

Effect of medroxyprogesterone and an aorta-derived cell growth inhibitor on B16 melanoma in mice.

An aorta-derived inhibitor of endothelial cell and tumor cell growth and medroxyprogesterone, which depresses collagenase expression in vivo, were tested alone and in combination against B16-F10 melanoma in C57BL/6 mice in such doses that either agent alone had little effect. Together, these agents retarded growth of subcutaneously transplanted tumor cells and reduced the number and size of pulmonary tumors after iv tumor cell injection. Of the treatments used, only the aortic factor administered alone prolonged life in mice with pulmonary tumors.

Animals↗
PubMed1983

Renal localization of heparan sulfate proteoglycan by immunohistochemistry.

Glomerular localization of heparan sulfate proteoglycan (HS-proteoglycan) has been studied immunohistochemically with a highly purified antiserum to bovine aorta HS-proteoglycan core protein. The specificity of the antiserum was enhanced by consecutive fibronectin and chondroitin sulfate-dermatan sulfate proteoglycan (CS-DS proteoglycan) affinity chromatography. The affinity-purified HS-proteoglycan antibody lacked cross-reactivity by enzyme-linked immunosorbent assays (ELISA) with CS-DS proteoglycan, fibronectin, laminin, and Type IV collagen. Reactivity of the antiserum with HS-proteoglycan antigen by ELISA was inhibited by HS core protein derived from CsCl density gradient centrifugation after heparinase treatment of the HS-proteoglycan. Immunofluorescent reactivity of the HS-proteoglycan antiserum was observed with bovine glomerular basement membrane, renal interstitium, Bowman's capsule, renal arterioles, and bovine aorta. No staining was seen with rat, mouse, or human glomeruli.

Animals↗
PubMed1981

Immunologic studies of bovine aortic and cartilage proteoglycans.

Rabbit antisera prepared against bovine cartilage and aortic proteoglycan monomer (PGM) were employed to identify and localize the distribution and cross-species reactivities of these PGMs. A specific reaction to both cartilage and aortic PGM was obtained as revealed by rocket immunoelectrophoresis of the immunogens against the respective antisera, with no reaction against bovine serum albumin or human fibronectin. These antisera appear to demonstrate tissue specificity. Indirect immunofluorescence studies with antiserum to aortic PGM on bovine aorta tissue revealed intense localization of fluorescence in the intima and superficial media with staining alone collagen fibers, around smooth muscle cells, and on the surface of elastin. When antiserum to cartilage PGM was applied to bovine aorta, staining was much weaker and localized more in the interfibrillar matrix. On the other hand, when antiserum to aortic PGM was used to stain bovine nasal septum cartilage, fluorescent staining was restricted to the pericellular matrix, in contrast to the diffuse, intense staining of both pericellular and extraterritorial staining by antiserum to cartilage PGM. Absorption with eigher bovine aorta or cartilage PGM abolished antibody activity against the absorbing molecules only. The immunologic distinction between the pericellular and extraterritorial cartilage matrix was demonstrated further when both antisera were studied with guanidine chloride (GuHCl)-extracted bovine nasal septum cartilage, when they both demonstrated the same pericellular matrix staining. Despite the tissue specificity, these antisera are not completely species specific, since staining in a similar pattern was observed in both human and rat tissues.

Animals↗
PubMed1981

Attachment of proteoglycans to collagen fibrils. Effect on human platelet aggregation.

We attached bovine aorta and cartilage proteoglycan fractions to extracted human skin collagen and studied the effect of such treatment on the platelet-aggregating activity of collagen. Attachment of bovine aorta and cartilage proteoglycan fractions to collagen was confirmed by electron microscopy and uronic acid analyses, Collagen attached with aorta proteoglycan retained its aggregating activity; collagen attached with cartilage proteoglycan caused a delayed platelet aggregation response. However, platelets preincubated with cartilage proteoglycan proceeded to normal aggregation when challenged by untreated collagen. Neither proteoglycan affected platelet aggregation induced by ADP. Preincubation of collagen with aorta proteoglycan did not protect the collagen from being inactivated by plasma. Of the proteoglycan fractions tested, only those from aorta were antithrombic and the antithrombic activity was plasma dependent.

Adenosine Diphosphate↗