Biomedical subjects

D M Gersten

Publications and source records attributed to D M Gersten.

At least 37 records · Page 2Linked to original sources

PubMed1991

On the relationship of amino acid composition to silver staining of proteins in electrophoresis gels: II. Peptide sequence analysis.

The quantification of proteins in silver-stained electrophoresis gels has been limited by the differences in "stainability" of different proteins. Despite efforts by many researchers, the precise basis of the reaction between silver reagents and polypeptides is still unclear, and, depending on the formulation, may even differ. We have tested the hypothesis that differences in stainability among proteins can be attributed to differences in di- or tripeptide composition. The results indicate that some order of protein structure other than short peptides accounts for the staining differences observed.

Amino Acid Sequence↗

PubMed1991

Comparison of the metabolic fate and tissue distribution of B700, an albumin-like melanoma-specific antigen with serum albumin in normal and tumor-bearing mice.

1. B700, a murine melanoma antigen, is a member of the serum albumin protein family, being closely related to murine serum albumin (MSA). 2. We have studied and compared the metabolic fate and anatomic distribution of radioiodinated B700 and MSA administered to semisyngeneic naive and tumor-bearing mice. 3. Labelled material from both proteins is excreted primarily into urine. 4. The rate of excretion of the two proteins is markedly different, with B700 having a shorter half-life in the body. 5. Despite their similar molecular weights, intact B700 represents approx. 30% of the radioactivity in the urine but only 4% of the MSA in the urine is intact. 6. These studies demonstrate that the host can readily distinguish between very similar normal (MSA) and tumor-associated (B700) molecules and process them differently. 7. Similar findings of differential fate and distribution have been reported in comparing other albuminoid molecules [Dueland S., Blomhoff R. and Pedersen J. I. (1990) Biochem. J. 267, 721-725].

Animals↗

PubMed1991

B700, an albumin-like melanoma-specific antigen, is a vitamin D binding protein.

B700, a murine melanoma-specific antigen, is a member of the serum albumin protein family. Other members include serum albumin and vitamin D binding protein. The primary structure and biochemical functions of B700, as well as its in vivo metabolic fate, are largely unknown. We compared murine albumin, vitamin D binding protein and B700 for their ability to specifically bind [3H]-1,25-dihydroxy-vitamin D3. Scatchard analysis revealed a single binding site for B700 with a Ka of 51,000 mol/l and a Bmax of 4.51 x 10(-7) mol/l. There was no significant difference in the Ka and Bmax among the albuminoid proteins. However, differences in the binding sites could be distinguished by competition experiments where vitamin D3, vitamin D2 or 7-dehydrocholesterol competed for the specific binding of 1.25-dihydroxyvitamin D3 to a greater extent by B700 than by vitamin D binding protein. The albumin binding site more closely resembles vitamin D binding protein than B700, but the data indicate that the binding function of the albuminoid proteins is conserved in B700.

Animals↗

PubMed1991

Mesothelial cells produce a chemoattractant for lung fibroblasts: role of fibronectin.

Pleural fibrosis may complicate several types of non-exudative pleural injury. Although the pathogenesis of such lesions is poorly understood, it is conceivable that mesothelial cells may recruit fibroblasts to sites of pleural damage. In order to test this possibility, conditioned medium from cultured rat mesothelial cells was tested for chemoattractant activity towards RL-87 rat lung fibroblasts. For this purpose, rat pleural or pericardial mesothelial cells were maintained in vitro for 6 to 96 h. Conditioned medium from each source was obtained at defined culture times and tested for chemotactic activity in a 48-well microchemotaxis assembly. A progressive, time-dependent increase in fibroblast chemoattractant activity was detected in both pleural and pericardial mesothelial cell conditioned medium samples. This effect was maximal in 96-h cultures. Checkerboard analysis revealed that the conditioned medium was truly chemotactic for lung fibroblasts. Characterization of the chemoattractant demonstrated that it was a nondialyzable (greater than 16 kD), thermolabile (100 degrees C for 15 min), acid-stable (pH 2.5), trypsin-sensitive, and pepsin-sensitive protein. The chemotaxin was shown to be fibronectin, since activity was abolished, in a dose-dependent manner, by treatment with anti-rat fibronectin antiserum as well as by passage through a gelatin agarose affinity column. This product consisted of two bands on sodium dodecyl sulfate polyacrylamide gel electrophoresis of apparent molecular masses 250 and 220 kD. The secretion of a mesothelial cell-derived fibroblast chemoattractant may play a role in the response of the pleura to injury and in the pathogenesis of pleural fibrosis.

Animals↗

PubMed1991

Serologic demonstration of the albuminoid nature of the B700 murine melanoma antigen.

Limited available evidence indicates that the B700 murine melanoma antigen is related to serum albumin, but potential relationships to other members of the serum albumin protein family have not yet been established. Using specific antibodies raised against each of the members of the albumin family, we have studied cross-reactivity by solid phase enzyme-linked immunosorbent assay and Western immunoblotting. We demonstrate that B700 is serologically cross-reactive to members of the serum albumin family, which includes alpha-fetoprotein and vitamin D binding protein. Therefore, B700 is part of the serum albumin family of proteins, although the mechanism underlying its specific expression by transformed melanocytes remains unknown.

Amino Acid Sequence↗

PubMed1990

Homology of the B50 murine melanoma antigen to the Ro/SS-A antigen of human systemic lupus erythematosus and to calcium-binding proteins.

B50 is a murine melanoma-associated antigen found in tight association with B700, a melanoma-specific antigen. B700-like molecules are produced by all melanomas tested to date, including those of murine, human, swine and hamster origin. We have used rabbit antibodies to B50 to determine whether B50 expression is also restricted to melanomas. The results demonstrate that B50 is a commonly occurring protein, or is immunologically cross-reactive to a commonly occurring protein; 29 of 29 cell lines tested bound anti-B50 antibodies. N-terminal amino acid sequence analysis indicates that B50 has significant homology to the Ro/SS-A antigen of human systemic lupus erythematosus and to calcium binding proteins; hence B50 is likely to be an RNA and/or calcium-binding protein.

Amino Acid Sequence↗

PubMed1990

B700, a melanoma-specific antigen, catalyzes metabolism of prostaglandin E2.

B700 is an albumin-like mouse-melanoma-specific antigen of unknown primary structure and biochemical function. The ability of mouse serum albumin to catalyze weak degradation of prostaglandin E2 has been utilized to compare functional similarities between B700 and mouse serum albumin. Both proteins catalyze the degradation of prostaglandin E2 to prostaglandin A2 and prostaglandin B2. This catalytic ability is related to the amino acid composition of the two proteins within the functional region rather than the 3-dimensional configuration, the activity is not altered upon boiling. The primary prostaglandin E2 metabolite in the presence of mouse serum albumin is prostaglandin B2, while prostaglandin A2 predominates in B700 catalyzed degradations. An additional product, presently unidentified, is produced during B700 catalyzed degradation of prostaglandin E2. Our studies indicate that the B700 protein has weak enzymatic activity for prostaglandin E2 similar to that of albumin. To our knowledge, B700 is the only melanoma antigen for which enzymatic activity has been demonstrated.

Animals↗

PubMed1989

The intracellular association of B700 and B50 murine melanoma antigens and their role in tumor rejection.

B700 and B50 are melanoma-specific antigens originally isolated from B16 murine melanoma. B700, which elicits a strong tumor rejection response, is present on all murine melanomas tested to date. We now demonstrate the presence of B50 in the other murine melanomas and find that the 2 molecules are non-covalently complexed with each other within the cells. We also show that hosts immunized with intact, irradiated melanoma cells produce antibodies that specifically recognize the B700 and B50 tumor antigens. These results suggest that B50 may also participate in the host response to melanoma growth.

Animals↗

PubMed1989

A system for automated DNA electrophoresis, molecular hybridization and electronic detection: II. Electronic detection.

We have designed and constructed an automated, computer-controlled, nucleic acid hybridization analysis system (Electrophoresis 1987, 8, 255-261). The system performs 9 simultaneous experiments, beginning with submarine electrophoretic separation of the restriction fragments and including microwave fixation of the separated fragments, denaturation, neutralization, prehybridization, hybridization, washing and drying. The final step is electronic detection of the hybridization pattern. The detector system consists of 90 Geiger-Mueller detectors arranged to simultaneously sample the 9 hybridizations at 10 positions each. The hybridization matrix is moved across the detectors by a robot arm in increments preprogrammed by the operator and the entire length of the matrix can be counted. The results are printed out as a plot of radioactive counts vs. distance from the origin of electrophoresis. We describe here the characteristics of the detection system.

DNA↗

PubMed1989

Albuminoid molecules: a novel, variability-generating cell-surface receptor system?

The mechanisms by which lymphoid cells produce infinitely variable molecules of the immunoglobulin protein superfamily have been recently elucidated. These molecules serve, in part, as the mediators of cell:cell recognition and interaction among lymphoid cells. However, the generality of those molecular mechanisms to occur in non-lymphoid cell types has not yet been established. In this paper, we propose that the serum albumin superfamily of proteins has the necessary characteristics to serve analogous functions in epithelioid cells, and we critique recent evidence which leads to this hypothesis.

Animals↗

PubMed1988

Demonstration of B700 cross-reactive antigens on human and other animal melanomas.

B700 is a melanoma-associated antigen originally detected by immunologic and biochemical criteria; it is expressed by several murine melanomas but is not detectable on any normal murine cells, or on murine nonmelanoma neoplasms. We have used antibodies raised against purified B700 to study the presentation of B700 and B700 crossreactive molecules on the surfaces of melanoma cells of various species and origins. The antibodies are shown to bind to all the melanoma cells tested, including five different murine melanoma lines (S91, JB/RH, JB/MS, K1735, and B16), three different B16 sublines (F1, F10, and BL6), three human, one hamster, and two swine melanoma cell lines. These results suggest the candidacy of B700-like molecules as "pan-melanoma" antigens.

Animals↗

PubMed1987

Melanoma antigens as modified normal gene sequences.

Melanomas are highly aggressive tumors with a well-documented antigenic nature. Several melanoma antigens have been reported, four of which, p97, Ia-like antigen, B700, and A have been implicated as having regions in common with normally occurring proteins. P97 has partial sequence homology with transferrin and lactotransferrin, Ia-like antigen is immunologically cross-reactive with alpha and beta chains of Ia-like proteins, A is a variant of alpha actin, and B700 resembles a normal melanosomal membrane protein. In addition, B700 has partial sequence homology to serum albumins. These observations suggest that melanoma tumors can produce antigenic proteins by modification of normally occurring proteins. The possible mechanisms are discussed.

Actins↗

PubMed1987

Temporal synthesis and presentation of antigens by cultured B16 melanoma cells.

Previous studies have demonstrated the presence of two distinct antigens, B700 and B50, which are unique to murine melanoma. One of these, B700 has been studied in detail, and is present on 5 different murine melanomas; it can function as a transplantation antigen in at least 3 of them (B16, JB/RH and K1735). The synthesis and presentation of these antigens has been studied as a function of cell culture conditions. Direct immunofluorescence studies of cells in serial culture indicate that the expression of B700 and B50 antigens at the cell surface and in the cytoplasm increases as a function of time in culture, over 1-5 days. By day 5, when the cells are confluent, all cells show some degree of antibody binding. Parallel 35S-methionine pulse chase labeling experiments show that incorporation into Triton soluble proteins, and Triton insoluble SDS soluble proteins, increases to a peak at 3.5 days after subculturing, then decreases as the cells reach confluence. Incorporation into proteins shed into the culture supernatant continued throughout the time course of cell growth to confluence. However, as the cells become confluent, total protein synthesis shifts towards greater production of the antigens (both cellular and shed). The sum of the results suggest that tumor growth may succeed in vivo by the wholesale production of "decoy" antigens.

Animals↗

PubMed1986

Murine melanoma-specific tumor rejection activity elicited by a purified, melanoma-associated antigen.

B700 is a melanoma-specific glycoprotein antigen, with a m.w. of 65,000 and an isoelectric point of 4.5; this antigen has been shown to bear significant sequence homology to a normally occurring protein, serum albumin. The production of B700 is apparently restricted to all the murine melanomas tested, since a variety of other transformed and untransformed cell lines do not contain detectable levels of this antigen. The capacity of B700 to function as a tumor-specific transplantation antigen (TSTA) is demonstrated in this study. This activity has been titrated, and it is shown that mice immunized with B700 are able to significantly inhibit the growth of B16 F10 melanomas after subcutaneous challenge; immunized mice can also inhibit the establishment and growth of experimental metastases in the lungs after i.v. challenge with B16 melanoma cells. The TSTA was found to cross-protect also against challenge with two other murine melanoma lines, JB/RH and K1735, but was specific in that the growth of two nonmelanoma lines (RBL-5 leukemia and MCA-105 sarcoma) was not affected. B700 is also shown in this study to be unrelated to other known murine tumor antigens, or to murine leukemia virus antigens. It is further shown that mice immunized with B700 produced antibodies specific to B700 that were not cross-reactive with albumins from various mammalian sources.

Animals↗

PubMed1986

Studies on the relationship of the B700 and B50 murine melanoma antigens.

The B50 and B700 proteins of B16 murine melanoma were studied; they were determined to be distinct, unrelated molecules. This was determined by V8 peptide mapping, N-terminal amino acid sequencing, absence of cross-reactivity with specific polyclonal antibodies, and monoclonal antibodies recognizing different epitopes.

Amino Acid Sequence↗

PubMed1985

Macromolecules mediate prostacyclin release from human umbilical artery.

Previous reports regarding the modulation of prostaglandin release from tissues by serum components did not identify these components. We have found that inhibition of prostacyclin release from human umbilical artery by human serum is attributable to serum macromolecules. We demonstrate that such inhibitory activity depends on macromolecular size and may result from macromolecule/cell surface interactions.

Arteries↗

PubMed1984

Amino-terminal variation in melanoma antigens.

Melanoma tumors express both common antigenic determinants and individually specific markers. A melanoma-specific glycoprotein antigen ( B700 ) with a molecular weight of approximately 65,000 daltons was detected on murine B16 melanoma cells but appears on other murine and human melanoma tumors. In order to determine the relationship between the B700 antigen and other melanoma antigens which have been described and to elucidate molecular changes that have taken place in the transformation from melanocyte to melanoma, we have purified the B700 glycoprotein to homogeneity. We have carried out amino acid composition analysis and partial sequence determinations and report that the B700 melanoma antigen shows similarities to serum albumin, but is not identical to this normal component. Moreover, amino-terminal variation occurs in the first 15 residues of the B700 antigen produced by separate B16 tumors.

Amino Acid Sequence↗

PubMed1984

Sex differences in blood protein patterns: a computer-assisted electrophoretic analysis of mid-molecular weight range proteins of human serum.

We have studied the sexual dimorphism of human serum proteins between the ranges of approximately 60,000 and 150,000 daltons using computerized imaging and densitometry. Methodology is presented, based on the TEXAC computer system for the detection, segmentation and integration of protein bands. The results are discussed in terms of potential future applications in computerized medical diagnosis.

Adolescent↗