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Biomedical subjects

E Ruoslahti

Publications and source records attributed to E Ruoslahti.

At least 289 records · Page 16Linked to original sources
PubMed1978

Affinity of fibronectin to collagens of different genetic types and to fibrinogen.

Fibronectin, a fibroblast surface protein, was purified from human and chicken plasma and extracts of cultured chicken fibroblasts with affinity chromatography on gelatin coupled to Sepharose particles. A fibronectin-like protein was also isolated from the plasma of Torpedo fish. The collagen binding properties of fibronectin were studied with several genetically distinct collagens. Heat denatured types I, II, and III collagens were equal in their binding capacity and more active than the native collagens or A and B chains. Native type III collagen was more active than the other native collagens. Human and chicken fibronectins showed approximately the same pattern of specificity. Identical specificities were shown by the plasma and fibroblast forms of chicken fibronectin. Two cyanogen bromide peptides of the collagen alpha1 (II) chain, CB8 and CB12, derived from different parts of the chain, were active in fibronectin binding. A polymer of the tripeptide pro-gly-pro, and polyproline were inactive. Fibronectin also binds to fibrinogen and fibrin. Comparison of this binding to collagen binding showed that fibrinogen inhibited binding of fibronectin to collagen, but was less active than native collagen. Two other fibrous proteins, tropoelastin and keratin, did not bind fibronectin. The binding of fibronectin to fibrinogen was inhibited by collagen and incorporation of fibronectin into blood clot in the cold was inhibited by gelatin. These results suggest that the binding of fibronectin to collagen and fibrinogen depends on the same binding site in the fibronectin molecule. It is proposed that cell surface fibronectin mediates attachment of cells to the collagenous extracellular matrix and to a temporary fibrin matrix in a wound.

Animals↗
PubMed1978

Early increase of serum alpha-fetoprotein in spontaneous hepatocarcinogenesis in mice.

The concentration of serum alpha-fetoprotein (AFP) was followed in C3H mice having a high incidence of spontaneous liver-cell cancer. No general elevation of serum AFP level with age was seen in mice without tumor. With a single exception, mice bearing hepatocellular carcinomas had increased serum AFP levels. In some mice this increase followed a biphasic course. Mice killed within 1 month of the time when an elevation of serum AFP was first observed had small tumors or no detectable tumor. Premalignant lesions were present in the livers of 11 out of 16 mice that had elevated AFP but no cancer, while only one out of 14 mice with normal AFP had such alterations. Our results strongly suggest that spontaneous hepatocarcinogenesis proceeds through almost the same premalignant lesions as chemically induced carcinogenesis, and that an increase in AFP production occurs early during this process, often preceding macroscopic lesions. Autologous antibodies to AFP were produced in a group of C3H mice by immunization with rat AFP. These anti-AFP antibodies reduced the amount of serum AFP but had no effect on the incidence of spontaneous hepatomas.

Animals↗
PubMed1978

Fibronectin synthesis by epithelial crypt cells of rat small intestine.

Synthesis of fibronectin in an epithelial cell line (IEC-6) established from rat small intestine was demonstrated by using immunofluorescence, radioimmunoassay, and collagen-binding. Internally labeled radioactive fibronectin isolated from the IEC-6 cells gave a single main band in sodium dodecyl sulfate/polyacrylamide gel electrophoresis under reducing conditions. Fibronectin isolated from rat plasma gave two closely spaced bands. The slower one had the same mobility as the epithelial cell fibronectin. The distribution of fibronectin in IEC-6 cells as detected by immunofluorescence was different from that described for fibroblasts and other cell types; fibronectin was present exclusively in regions of cell-to-cell contact. No fluorescence was detected on the surface membrane facing the culture medium or underneath the cells. This suggests that fibronectin may not be involved in the adhesion of the epithelial cells to the growth surface but could mediate cell-to-cell contacts. In microscopic sections of the small intestine, immunofluorescent staining with antifibronectin serum was strong in the basement membrane underlying the epithelial cells in the crypts. The in vitro synthesis of fibronectin by the crypt cells and its abundant presence in the basement membrane underlying the same cells in vivo suggests that fibronectin is a structural component of the basement membrane, and that it may be, at least in part, synthesized and deposited by the intestinal epithelium.

Animals↗
PubMed1978

Immunochemical properties of alpha-fetoprotein (AFP) and antibodies to autologous AFP.

Alpha-fetoprotein (AFP) is a strong immunogen when injected into another species, but does not elicit an immune response in the species of origin of the AFP. AFPs from different mammalian species are crossreactive. AFP and albumin show sequence homology. They do not crossreact in their native state, but their unfolded (reduced and carboxamidomethylated) forms are immunologically crossreactive. Antibodies to autologous AFP can be induced in animals by immunization with heterologous or modified homologous AFP. These antibodies eliminate the AFP normally measurable in the serum and delay the elevation of serum AFP caused by hepatomas, but do not protect against such tumors.

Amniotic Fluid↗
PubMed1978

Demonstration of fibronectin in human cerebrospinal fluid.

Fibronectin is a glycoprotein found in plasma (cold-insoluble globulin), connective tissues, and cultures of fibroblasts and astroglial cells. This paper describes the identification of fibronectin in human CSF. Fibronectin in CSF was immunologically indistinguishable from the plasma form, as shown by double-diffusion analysis and by radioimmunoassay specific for fibronectin. Fibronectin was isolated from human CSF by affinity chromatography on Sepharose-coupled gelatin and was further analyzed by SDS-polyacrylamide gel electrophoresis. It showed a polypeptide band similar to that of plasma fibronectin. The fibronectin concentration in CSF of 17 neurological outpatients without demonstrable organic lesion in the CNS was 3.0 +/- 1.6 microgram/ml (mean +/- S.D.) which is about 0.6% of total CSF protein. In CSF of 11 MS patients, the concentration was significantly (p less than 0.005) lower (1.6 +/- 0.2 microgram/ml). Of patients with brain tumors, seven had very low levels, three were normal, and two had very high levels. The cause for the low levels in MS and tumor patients is not known.

Adult↗
PubMed1978

Immunochromatography on insolubilized antibodies of very low affinity: application to immunoadsorbence of bovine alpha-fetoprotein.

Cross-reactive antibodies were utilized to prepare immunoadsorbents possessing a very low affinity to bovine alpha-fetoprotein (AFP). A goat anti-human AFP serum cross-reactive with bovine AFP was first depleted of antibodies reactive with bovine AFP in immunodiffusion. The remaining antibodies from this serum and gamma-globulin from a sheep antiserum against rabbit AFP, without prior absorption, were coupled to Sepharose. Chromatography of fetal calf serum on these adsorbents resulted in retardation of bovine AFP relative to other proteins. A major part of the AFP eluted from the columns with phosphate-buffered saline. The rest eluted as a sharp peak with a small quantity of 4 or 6 M urea. The elution of AFP with the initial column buffer has made it possible to prepare pure AFP that has not been subjected to the chaotropic elution buffers usually employed in affinity chromatography. Elimination of the washing step and the ease of elution has allowed purification of gram amounts of AFP. The fact that immunoadsorbents prepared from antibodies with no detectable reactivity in immunodiffusion still caused delayed elution in chromatography suggests that this procedure may be useful in search of proteins cross-reactive with a known protein.

Animals↗
PubMed1977

Antigenic differences in nuclear proteins of normal liver and hepatoma. Identification of a nuclear protein present in hepatocytes but absent in hepatoma cells.

A nuclear antigen was detected in the mouse liver nonhistone protein fraction by using antibodies to whole liver cells. The antigen was purified to homogeneity from perchloric acid extracts of liver tissue. It gave a single band corresponding to tool wt 21,000 in sodium dodecyl sulfate gel electrophoresis. Amino acid and carbohydrate analysis showed predominance of the acidic amino acids, lack of proline, and absence of carbohydrate. Immunofluorescence staining of liver sections confirmed the nuclear localization of the antigen. Its tissue distribution was studied by using radioimmunoassay. Of the various tissues extracted for analysis, the liver contained the highest amounts of the antigen, about 1 mug/mg of solubilized liver protein. Other tissues examined showed 2-4 percent of the amount of antigen present in the liver. Two transplantable hepatomas in C3H/HeJ and C57L/J mice, respectively, and three spontaneous C3H hepatomas showed greatly decreased levels of the antigen compared to normal liver. The amount of antigen in hepatomas varied from nondetectable to 2 percent of the amount of antigen found in the livers of the mice. The antigen was also found in the blood. The antigen was found in high concentrations (up to 13 mg/ml) in the urine of normal mice. This suggests identity with the previously known mouse urinary protein (MUP). In addition to the extremely high urinary output, the properties found to be shared by MUP and the nuclear antigen included similar serum concentrations (2-60 mug/ml), a sex difference with lower values in females, same molecular size as determined by gel filtration, and immunological identity. The nuclear localization of MUP and its disappearance from hepatomas suggest that it may have an important regulatory function.

Animals↗
PubMed1977

Binding of soluble form of fibroblast surface protein, fibronectin, to collagen.

Fibronectin, a plasma protein immunologically identical with a major surface protein of normal fibroblasts, was found to bind to collagen and gelatin. A solid phase enzyme immunoassay was used for the binding tests. Collagen, gelatin or various control proteins were adsorbed to a plastic surface. Binding of fibronectin was detected using purified fibronectin antibodies conjugated to alkaline phosphatase. Circulating fibronectin and fibronectin obtained from fibroblast cultures both showed specific binding to collagen and gelatin. Preparative affinity chromatography of plasma on gelatin coupled to Sepharose gave electrophoretically and immunologically pure fibronectin in high yields. Malignantly transformed fibroblasts lack surface fibronectin. Our findings suggest the possibility that this results in a lack of anchorage to the surrounding intercellular matrix, which could contribute to the malignant growth behavior.

Blood Proteins↗
PubMed1977

Genetic control of alpha-fetoprotein synthesis in the mouse.

To approach the genetic mechanism that turns off the synthesis of alpha-fetoprotein (AFP) after birth, we assumed that a change in this mechanism might affect the low basal level of AFP that can be detected in the adult organism. The concentration of AFP was therefore determined for serum from adult mice of 27 different inbred strains. With one exception, this basal level was between 34 and 173 ng/ml, which is about 10(5)-fold less than the serum concentration at birth. In one strain, BALB/c/J, the AFP level was found to be considerably increased; it was about 10-fold higher than in other strains at 9-10 wk of age. Two other substrains of BALF/c mice showed normally low AFP levels. Kinetic studies show that the rate with which AFP disappears from serum after birth is reduced in BALB/c/J mice as compared to other strains. The increased AFP level of BALB/c/J mice appears to be due to an increased rate of synthesis of AFP, since the rate of catabolism of AFP was found to be normal in these mice. Genetic analysis was performed by crossing BALB/c/J mice with mice having an ordinary AFP level, followed by determination of AFP levels in mice of the F1 and F2 generations as well as in back-cross mice. The results clearly indicate that the increased AFP level in BALB/c/J mice is controlled by a single recessive Mendelian gene, which has been named Raf (for regulation of alphafetoprotein). The Raf gene could be directly involved in the regulation of AFP synthesis, but it may also control AFP levels only indirectly, e.g., by regulating the synthesis of a hormone that controls AFP synthesis.

Age Factors↗
PubMed1977

Alphafetoprotein is not a component of the 8 S estradiol receptor from the immature mouse uterus or brain.

The hypothesis that alphafetoprotein (AFP) could be a consitituent of the estradiol receptor in the uterus and brain of the immature mouse has been tested. Cytosols prepared from 2 week-old mice were depleted of AFP by immunoadsorption with a Sepharose-coupled anti-mouse AFP anti-serum. Aliquots of these cytosols containing nondetectable levels of AFP by RIA were then brought to 0.4 M KCl to convert 8 S estradiol receptors to the 4-5 S forms, reacted either with anti-AFP or with a control anti-IgG immunoadsorbent, labeled with 3H-estradiol, and centrifuged on glycerol gradients. There was no, or very little, loss of estradiol receptors in the experimental as compared to the control cytosols indicating that AFP is not a constituent of the 8 S estradiol receptor.

Animals↗
PubMed1977

Effect of specific immunotherapy with preimmunization against alpha-fetoprotein on a mouse transplantable hepatoma.

Antibodies to autologous alpha-fetoprotein (AFP) were produced in mice by immunization with rat AFP. C57L/J mice with or without such antibodies were inoculated sc or ip with controlled numbers of cells of the syngeneic, AFP-producing, BW 7756 hepatoma. There was a linear relationship between circulating AFP and tumor mass, with elevated AFP being detectable earlier than the tumor. The AFP levels of the immunized mice were generally lower than those of control mice, and tumors could be detected before elevated concentrations of AFP appeared in the circulation. An extensive series of transplantations with varying protocols for immunization did not protect against tumor and did not affect the rate of tumor growth.

Animals↗
PubMed1977

Radioimmunoassay of capsular polysaccharide antigens of groups A and C meningococci and Haemophilus influenzae type b in cerebrospinal fluid.

Sensitive radioimmunoassays capable of measuring 0-5 ng/ml of the Haemophilus influenzae type b polysaccharide and 2 ng/ml of the groups A and C meningococcal polysaccharides were developed and used to detect these substances in cerebrospinal fluid (CSF). Polysaccharide of the causative agent was detected in the CSF of 14 out of 15 patients with Haemophilus influenzae type b meningitis, in 18 out of 23 patients with group A, and in two out of four patients with group C meningococcal meningitis. In some cases the antigen could be detected even after three days of antibacterial treatment. No false positive reactions were seen. The assay procedure could be shortened to approximately three hours. These assays could be useful in routine diagnostic work and epidemiological investigations.

Antigens, Bacterial↗
PubMed1976

Specific anti-fibroblast cytotoxicity of antibodies to fibroblast surface antigen.

An antiserum to SF antigen was shown to be selectively cytotoxic to two human fibroblast lines, while two tumor cell lines (one melanoma and one Hela cell line) were resistant. The selective cytotoxicity was also demonstrable in mixtures of fibroblasts and tumor cells. The cytotoxic effect was abrogated by admixture of human serum containing SFA.

Antigen-Antibody Reactions↗