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Biomedical subjects

I Damjanov

Publications and source records attributed to I Damjanov.

At least 37 records · Page 2Linked to original sources
PubMed1994

Globo-series carbohydrate antigens are expressed in different forms on human and murine teratocarcinoma-derived cells.

The glycolipids of human teratocarcinoma-derived cell line NCCIT were compared with those of 5 murine teratocarcinoma-derived cell lines. Glycolipid antigens were identified by cell surface immunofluorescence and high-performance thin-layer chromatography (HPTLC) immunostaining with a panel of monoclonal anti-carbohydrate antibodies. Human NCCIT embryonal carcinoma (EC) cells contained extended globo-series glycolipids Gb5 (galactosyl globoside) and GL7 (sialyl galactosyl globoside) recognized by antibodies to stage-specific embryonic antigens 3 and 4 (SSEA-3 and -4). SSEA-4 was not detected by immunofluorescence on the surface of any of the 5 murine teratocarcinoma-derived cell lines examined; however, SSEA-3 was detected on the surface of murine cell lines resembling primitive endoderm (JC44, NF-PE) and trophectoderm (E6496D). HPTLC analysis revealed a large amount of globoside (Gb4) in these differentiated cells, which may account for their labeling with anti-SSEA-3 antibody. Globo-series glycolipids were also detected in murine EC cells; however, differences were noted between the 2 cell lines examined. F9 cells contained primarily Gb4 and Forssman glycolipid, whereas NF-1 cells contained only minor amounts of Gb4 and lacked Forssman glycolipid entirely. Our results, coupled with the known distribution of Forssman antigen in the egg cylinder-stage mouse embryo, suggest that F9 and NF-1 murine EC cells are replicas of cells at different stages of development of the embryonic ectoderm. Glycolipids of normal mouse embryos were examined for comparison. Gb4 and Forssman glycolipid were presents in both embryonic and extra-embryonic tissues, whereas Gb5 and GL7 were restricted to visceral yolk sac and placenta. Our results demonstrate that human and murine teratocarcinoma-derived cells both synthesize extended globo-series glycolipids; however, oligosaccharide chain elongation takes different pathways in the 2 species. These differences reflect species-related and cell type-specific patterns of glycosylation.

Animals↗
PubMed1994

Glycolipids of germ cell tumors: extended globo-series glycolipids are a hallmark of human embryonal carcinoma cells.

Glycolipids of human germ cell tumor lines were analyzed to define the most common immunohistochemical profiles of embryonal carcinoma (EC), differentiated derivatives of EC, yolk sac carcinoma (YC) and choriocarcinoma (CC). Glycolipid composition was examined by high-performance thin-layer chromatography (HPTLC) combined with immunostaining with a panel of anti-carbohydrate monoclonal antibodies (MAbs). All EC cell lines were found to contain high levels of globo-series glycolipids, including globotriosylceramide (Gb3), globoside (Gb4), Gb5 (Gal beta 1-->3Gb4) and GL7 (sialyl Gal beta 1-->3Gb4). Somatic differentiated derivatives (e.g., EC cells treated with retinoic acid) contained decreased levels of globo-series glycolipids and increased levels of lacto- and ganglio-series glycolipids, including GD3, GT3 and GD2. CC cell lines contained relatively large amounts of Gb3 but did not contain extended globo-series glycolipids Gb5 and GL7. CC cell lines also contained a macroglycolipid reactive with the antibody to SSEA-1 (Lex). Glycolipids were not detected in two YC cell lines, while other YC cell lines contained globo-series core glycolipids (Gb3 and Gb4) and gangliosides. We conclude that EC, YC and CC have distinct patterns of membrane glycolipid expression that can be identified by HPTLC and immunostaining. Our results indicate that globo-series glycolipids Gb5 and GL7, which carry stage-specific embryonic antigens 3 and 4 (SSEA-3 and SSEA-4), are a hallmark of human EC cells. Cell lines derived from human germ cell tumors that do not express Gb5 and GL7 deserve to be re-evaluated, since they may represent different stem cells, most likely equivalent to somatic cells and their developmentally committed precursors (e.g., neuroblasts).

Biomarkers, Tumor↗
PubMed1994

Molecular cloning and characterization of murine cyclin E.

Using a monoclonal antibody developed to a mouse trophectodermal carcinoma stem cell line E6496D lysate, we have identified the gene that encodes murine cyclin E. The cDNA contains a consensus cyclin box and a long 3' untranslated region and shares over 75% homology with human cyclin E cDNA. We show that the gene is expressed in fetal tissues, embryonal carcinoma F9 cells and yolk sac carcinoma PYS-2 cells, but is not expressed in preimplantation stages of development. In adult tissues, cycE mRNA is detectable in the spleen and to a lesser extent in the testis and brain. These data show that cycE is developmentally regulated and unevenly expressed in fetal and adult mouse tissues.

3T3 Cells↗
PubMed1994

Inhibition of proliferation and induction of differentiation of pluripotent human embryonal carcinoma cells by osteogenic protein-1 (or bone morphogenetic protein-7).

BACKGROUND: Osteogenic protein-1 (OP-1) is a member of the transforming growth factor-beta super family closely related to the bone morphogenetic proteins and also known as bone morphogenetic protein-7. Other members of this family of growth factors influence cell differentiation as well as cell growth in a number of systems. The Drosophila homolog encoded by the decapentaplegic locus is involved in dorsal-ventral pattern formation during embryogenesis, whereas the expression of several bone morphogenetic proteins including OP-1 is developmentally regulated in mammalian embryos. EXPERIMENTAL DESIGN: The effect of recombinant human OP-1 on the proliferation and differentiation of an established pluripotent human embryonal carcinoma (EC) cell line, NTERA2, and three nullipotent human EC cell lines, 2102Ep, 833KE and TERA-1, was investigated. These cells were grown under reduced serum conditions, and differentiation was monitored by morphology and expression of marker antigens. RESULTS: OP-1 inhibited proliferation of NTERA2 and induced their differentiation, marked by changes in cellular morphology, the loss of EC cell antigens (SSEA3, SSEA4, the liver isozyme of alkaline phosphatase), and the appearance of new antigens, notably SSEA1 and class 1 major histocompatibility complex antigens. These changes were irreversible and did not involve significant cell degeneration or cell death. The OP-1-induced differentiation of NTERA2 appeared distinct from that induced by either retinoic acid or hexamethylene bisacetamide. Nevertheless, OP-1 did induce the homeobox gene, HOXA1. By contrast, OP-1 elicited only a limited and partial response from the nullipotent EC cell lines. CONCLUSIONS: Our results suggest that pluripotent human EC cells differentiate in response to OP-1 and that this factor can modulate the differentiation induced by retinoic acid. Like other members of the transforming growth factor-beta super family, OP-1 might play an inductive role in the early embryo. The results also suggest a possible therapeutic value for OP-1 in the treatment of some germ cell tumors.

Acetamides↗
PubMed1993

Functional epidermal growth factor receptor localizes to the postacrosomal region of human spermatozoa.

The human epidermal growth factor receptor was detected immunohistochemically in the postacrosomal region of ejaculated human sperm and, when immunopurified and exposed to [gamma-32P]ATP, was found to be autophosphorylated. Localization of an apparently enzymatically active epidermal growth factor receptor to spermatozoa suggests that epidermal growth factor receptor-ligand interactions may play a role in gamete physiology or in fertilization.

Antibodies, Monoclonal↗
PubMed1993

Students' psychosocial characteristics as predictors of academic performance in medical school.

PURPOSE: To investigate the incremental effects of selected psychosocial measures--beyond the effects of conventional admission measures--in predicting students' academic performances in medical school. METHODS: In 1989-90, 210 second-year students at Jefferson Medical College were each asked to complete 11 psychosocial questionnaires that were then used as predictors of performance measures in medical school. The students' scores on three subtests of the Medical College Admission Test (MCAT) were also used as predictors. Three composite measures of performance were used as the criterion measures: basic science examination grades, clinical examination grades, and ratings of clinical competence. A multiple regression algorithm (general linear model) was used for statistical analysis. RESULTS: The response rate was 83% (175 students). When the psychosocial measures were added to the statistical models in which the common variances of the MCAT scores were already determined, significant increments in the common variances were observed for two of the three performance measures: basic science grades and clinical examination grades. Whereas only 4% of the common variance in the ratings of clinical competence could be accounted for by the MCAT scores, 14% could be accounted for by the psychosocial measures. CONCLUSION: The "noncognitive," or psychosocial, measures increased the magnitude of the relationships between the predictive and criterion measures of the students' academic performances, beyond the magnitude attained when only the conventional admission measures were used. Therefore, psychosocial measures should be considered as significant and unique predictors of performance in medical school.

Algorithms↗
PubMed1993

Estrous-cycle-related changes in the expression of mouse endometrial and oviductal glycoproteins.

Glycoproteins of mouse endometrium and oviduct were analyzed by lectin overlay blotting of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)-separated whole-cell extracts, sampled at each of the four phases of the normal estrous cycle. Nine endometrial and 5 oviductal glycoproteins were found only in one of these two organs or showed cyclic changes in their expression as revealed by wheat germ or Ricinus communis I lectin blotting. Glycoproteins of the same molecular weight showed different expressions in the endometrium as compared with the oviduct. Thus one can conclude that the expression of the endometrial and oviductal glycoproteins is cyclic, but organ specific.

Animals↗
PubMed1993

Two-dimensional electrophoretic analysis of endometrial cellular proteins synthesized during early pregnancy in the mouse.

The synthesis of cellular proteins during early pregnancy was analyzed in mouse endometria incubated in vitro in the presence of [35S]-methionine. Endometrial proteins labelled on days 3 and 5 of pregnancy were compared with proteins from nonpregnant proestrus-phase endometrium. We have identified 23 proteins that were differentially expressed. These proteins were divided into four groups: (1) 10 proteins synthesized most prominently in nonpregnant proestrus-phase endometrium that decrease or disappear in pregnancy; (2) 4 proteins that are synthesized only on day 3, i.e., in the immediate preimplantation period; (3) 3 proteins that appear only on day 5 coincidentally with the development of decidua; (4) 5 proteins that are synthesized by both day 3 and day 5 endometria but are not found in the nonpregnant endometrium. Hence, the synthesis of some endometrial cellular proteins increased and others decreased in early pregnancy. The function of these proteins is unknown. Four proteins (Mr 26, 51, 52 and 70 kDa), 2 of which are both cell associated and secreted (Mr 52 and 70 kd) were selectively synthesized in the preimplantation period and thus may mediate implantation.

Animals↗
PubMed1993

Pathogenesis of testicular germ cell tumours.

Testicular germ cell tumours are subdivided clinically into two major groups: seminomas and non-seminomatous germ cell tumours (NSGCT). The relationship of seminomas to NSGCT remains controversial. The pathogenesis of NSGCT has been studied experimentally in mice, but there are no adequate experimental models of seminomas in laboratory rodents. Experiments with tumour cell lines derived from animal tumours have generated useful data for the better understanding of the biology of stem cells, such as embryonal carcinoma and yolk sac tumour. The final answer to questions pertaining to the histogenesis and classification of human germ cell tumours will however be obtained only after appropriate tumour cell lines of human origin are cloned.

Animals↗
PubMed1993

Glycoproteins of mouse vaginal epithelium: differential expression related to estrous cyclicity.

We used lectin overlay blotting and SDS-PAGE to analyze the estrous cycle-specific expression of mouse vaginal epithelial glycoproteins. Seven lectins chosen for their differential carbohydrate-binding specificity revealed 15 glycoproteins that showed cycle-related expression. Each lectin had a unique binding pattern different from the patterns revealed by other lectins. However, several estrous cycle phase-specific glycoproteins reacted with more than one lectin. The most prominent of these glycoproteins (M(r) 92-95 KD) was weakly expressed in late diestrus and fully expressed only in proestrus, coincident with the transformation of two superficial layers of vaginal squamous epithelium into mucinous cuboidal cells. Electron microscopic lectin histochemistry revealed the glycoproteins in the mucinous granules of surface cuboidal cells and in the lumen of the vagina. Our results illustrate the complexity of glycoconjugate synthesis in mouse vagina and reveal the distinct cycle-specific patterns of individual glycoprotein expression. These cyclic glycoproteins could serve as vaginal biochemical markers for the specific phases of the estrous cycle.

Animals↗
PubMed1993

Retinoic acid-induced differentiation of the developmentally pluripotent human germ cell tumor-derived cell line, NCCIT.

BACKGROUND: Germ cell tumors are empirically divided into seminomas and nonseminomatous germ cell tumors (NSGCT). Some authorities consider seminomas to be the precursors of NSGCT, whereas others consider them as distinct and unrelated neoplasms. Here, we report that the human NSGCT-derived stem cell line, NCCIT has hybrid features of seminoma and embryonal carcinoma, and suggest that this cell line could be useful for studying the relationship of seminoma to NSGCT. EXPERIMENTAL DESIGN: NCCIT, a developmentally pluripotent permanent cell line derived from a mediastinal NSGCT was karyotyped and characterized morphologically, immunochemically, and biochemically. The cells were grown under standard tissue culture conditions and were also exposed to retinoic acid to induce differentiation. RESULTS: The dividing NCCIT stem cell populations consist of vimentin-positive, keratin-negative cells that do not express desmoplakin or cadherin E (uvomorulin) and are not interconnected with one another. These cells have a high nucleocytoplasmic ratio and contain few cytoplasmic organelles, except for free ribosomes and a small number of mitochondria. Lacto- and globoseries oligosaccharide antigens recognized with antibodies to murine stage specific antigens 1, 3 and 4 (SSEA-1, SSEA-3 and SSEA-4), and human teratocarcinoma mucin-like antigen TRA-1-60 and TRA-1-81 are coexpressed on the cell membranes of a considerable number of stem cells. On most cells alkaline phosphatase can be detected by enzyme histochemistry. The placental isoenzyme of alkaline phosphatase was demonstrated by Western blotting in cell extracts. The liver/bone/kidney isoenzyme of alkaline phosphatase is immunochemically detected on 40% of cells. The culture supernatants also contain chorionic gonadotropin and alpha-fetoprotein, presumably derived from trophoblastic and yolk sac-like cells. The cells are hyperdiploid (chromosome range from 54 to 64) and show prominent structural chromosomal aberrations, mostly deletions and isochromosomes. Retinoic acid treatment inhibited the growth of NCCIT cells and induced stem cell differentiation into keratin, glial fibrillary acid protein, and neurofilament-positive somatic cells. The differentiation was associated with the disappearance of oligosaccharide surface antigens typical of the undifferentiated stem cells; a loss of proteins typical of undifferentiated cells and the appearance of new proteins; and the deposition of extracellular matrix. CONCLUSIONS: NCCIT is a developmentally pluripotent cell line that can differentiate into derivatives of all three embryonic germ layers (i.e., ectoderm, mesoderm, and endoderm) and extraembryonic cell lineages. We suggest that this cell line could be a malignant replica of human cleavage stage embryonic cells with features intermediate between seminoma and embryonal carcinoma.

Adult↗
PubMed1993

Rhenium-186-labeled monoclonal antibodies for radioimmunotherapy: preparation and evaluation.

Rhenium-186 has been determined to be a leading radionuclide for radioimmunotherapy. However, the use of 186Re has been limited due to the lack of a convenient and efficient method by which the radionuclide can be bound to monoclonal antibodies. We have developed a simple technique to label IgM, IgG, fragmented antibodies and tumor necrosis factor-alpha with 186Re. This technique uses ascorbic acid (AA) for controlled reduction of antibody disulfide groups to sulfhydryls and SnCl2 in citric acid for the reduction of 186ReO4-. The labeling yields as determined by instant thin-layer chromatography, molecular filtration and gel filtration were greater than 95% and the colloid formation was less than 5%. The labeled antibodies were stable when challenged with 100 and 250 molar excess of DTPA and HSA for 24 hr at 37 degrees C. SDS-PAGE analysis and autoradiography of labeled IgM, IgG and F(ab')2 monoclonal antibodies indicated uniform labeling and that no fragmentation of the monoclonal antibodies had taken place during the labeling procedure. Immunospecificity of 186Re-labeled human neutrophil specific IgM, as determined by in vitro antigen excess assay, was comparable to that of indium-111-labeled c-DTPA-IgM and technetium-99m-labeled-IgM. A nuclear histone specific 186Re-TNT-1-F(ab')2 was evaluated in mice bearing experimental tumors. The tumor/muscle ratios at 4 and 24 hr were 5.9 +/- 0.21 and 13.8 +/- 6.7, respectively compared to that of 2.4 +/- 0.3 at 4 hr p.i. with a nonspecific protein. The labeling technique is simple, reliable and has already been adapted to a single-vial kit preparation.

Animals↗
PubMed1993

Teratocarcinoma: neoplastic lessons about normal embryogenesis.

Germ cell tumors of the testis and the ovary have been studied extensively in humans and experimental animals. Murine teratocarcinomas proved to be one of the best experimental models for elucidating the histogenesis of these tumors and the nature of their undifferentiated stem cells. These spontaneous and experimentally induced tumors, especially those produced from early postimplantation stage embryos, provided a wealth of data about the differentiation of tumor stem cells and the regulation of their growth. This made it possible to draw parallels between the teratocarcinoma cells and their normal equivalents in the embryo. Cumulative data indicate that neoplastic development of murine embryonic cells is just one of the possible ontogenic pathways these cells can take while proliferating in various developmental fields. The malignancy of teratocarcinoma stem cells is determined genetically but can be regulated epigenetically. Development of stem cells in murine teratocarcinomas parallels events in the normal embryo, suggesting that events in the tumor have their normal regulatory counterparts in the embryo proper. The study of early embryos has provided data relevant for oncology, while the study of murine teratocarcinoma helped elucidate some basic developmental events occurring normally in the embryo.

Animals↗
PubMed1992

Evaluation of biological response modifiers in the enhancement of tumor uptake of technetium-99m labeled macromolecules. A preliminary report.

Imaging tumors with radioactive monoclonal antibodies remains attractive but continues to be challenging. With the hypothesis that the use of biological response modifiers (BRMs) may augment the tumor uptake, technetium-99m(99mTc)-labeled tumor necrosis factor (TNF) and nuclear histone specific TNT-1-F(ab')2 were evaluated in tumor bearing mice given a single dose of interferon (IFN). Ukrain or pokeweed mitogen as BRMs. As early as 1.5 h post injection (p.i.) of the radioactive macromolecules, the absolute tumor uptake (% administered dose/g) of each agent was enhanced (e.g., TNF, control = 1.8 +/- 0.4, Ukrain = 3.2 +/- 0.5, P = 0.006) and tumor to muscle ratios were elevated (e.g., TNF, control a 4.1 +/- 2.2, interferon 8.3 +/- 2.7, P = 0.01). The absolute tumor uptake remained practically unchanged at 4 h p.i. Generally with BRMs, the blood clearance was rapid and tumor/blood ratios and tumor/muscle ratios were higher than in the control group, increasing to greater than 200% for IFN as a BRM. The early enhancement in tumor uptake of macromolecules, leading to excellent delineation of tumors by scintigraphy is highly encouraging and warrants further studies to explore the full potential of BRMs.

Animals↗
PubMed1992

Analysis of purified human liver alpha-L-fucosidase by western-blotting with lectins and polyclonal and monoclonal antibodies.

Western-blot analysis [with lectins, polyclonal antibodies (pAbs) and four monoclonal antibodies (mAbs)] was employed to investigate the structural relationship between the separated isoforms and subunits of purified human liver alpha-L-fucosidase. SDS/PAGE and Western-blot analysis indicated the presence of two protein bands of 51 kDa and 56 kDa that were recognized by the pAbs. Polyacrylamide-gel isoelectric focusing (PAG-IEF) followed by blotting indicated that the pAbs and mAbs recognized at least five fucosidase isoforms (pI values 3.6-6.0). Lectin blotting indicated an enrichment of sialic acid residues in the more acidic isoforms. Western-blot analysis indicated that four mAbs recognized the 51 kDa subunit and at least two mAbs recognized the 56 kDa subunit. The subunit composition of the isoforms (separated by PAG-IEF) of human liver alpha-L-fucosidase was investigated by SDS/PAGE. One or two closely spaced bands were found for each isoform with a trend of increasing relative amounts of the high-molecular-mass band in the more acidic isoforms relative to the more neutral isoforms. Neuraminidase treatment of alpha-L-fucosidase resulted in a decrease in the amount of the high-molecular-mass subunit and an increase in the amount of the low-molecular-mass subunit, suggesting that these subunits are related at least in part by sialic acid residues. In addition, blotting with lectins indicated the presence of sialic acid residues only in the high-molecular-mass subunit. N-Glycanase treatment led to the disappearance of the glycosylated 56 kDa and 51 kDa protein bands and the appearance of non-glycosylated protein bands at 48 kDa and 45 kDa. The overall results indicate that (1) N-glycosylation contributes to, but does not account completely for, structural differences in the fucosidase subunits and (2) the more acidic isoforms of fucosidase contain enriched relative amounts of the sialylated high-molecular-mass subunit.

Animals↗
PubMed1992

Transdifferentiation of murine squamous vaginal epithelium in proestrus is associated with changes in the expression of keratin polypeptides.

The superficial layers of the stratified squamous epithelium of the murine vagina undergo transdifferentiation into cuboidal mucinous cells during the proestrus phase of the normal estrous cycle. In contrast to their squamous progenitor cells which have the cytoskeletal characteristics of squamous epithelium, mucinous cells express keratin polypeptides typical of simple nonstratified epithelia. Accordingly, the transdifferentiation of squamous cell into mucinous cells involves not only a change in cell morphology but also a switch in the expression of keratin polypeptides. These data indicate that the stratified squamous cells of the vagina are not terminally differentiated and their phenotype can be hormonally modulated.

Animals↗