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Biomedical subjects

U Sahin

Publications and source records attributed to U Sahin.

At least 37 records · Page 2Linked to original sources
PubMed1997

RP1, a new member of the adenomatous polyposis coli-binding EB1-like gene family, is differentially expressed in activated T cells.

Cross-linking of the CD3 and CD28 molecules on T lymphocytes represents one of the most effective signals for T lymphocyte activation and triggering of their cytotoxic effector function. To identify genes that are expressed in T cells after stimulation, mRNA from T lymphocytes that had been activated by the simultaneous stimulation of the CD3 and CD28 trigger molecules was transcribed for a differential mRNA display analysis into cDNA and was compared with cDNA from CD28- or CD3-activated or resting lymphocytes. Differential expression was confirmed subsequently by Northern blot analysis. One of the cDNA fragments expressed specifically in CD3- and CD28-activated T cells was designated RP1. The predictive protein-coding region of RP1 had a significant homology to members of the recently found adenomatous polyposis coli (APC) protein-binding EB1 gene family, which codes for yet unknown protein(s). Bacterially expressed RP1 protein revealed specific binding to wild-type but not to mutated APC protein. The rapid up-regulation of RP1 mRNA in properly activated T cells suggests that this gene might belong to the immediate/early gene family, which controls the signal transduction cascade downstream of the TCR. As the expression level of the RP1 gene in activated T cells and a spectrum of tumor-derived cell lines correlates with the proliferative status of the cells, members of the EB1-like gene family may not only be involved in the tumorigenesis of colorectal cancers but may also play a role in the proliferative control of normal cells.

Adenomatous Polyposis Coli↗
PubMed1997

Molecular definition of a novel human galectin which is immunogenic in patients with Hodgkin's disease.

Using autologous serum for the immunoscreening of a cDNA expression library derived from tissue involved by Hodgkin's disease, a new 36-kDa protein with the characteristics of galectins (S-type lectins) was detected. Sequence analysis of the cDNA clone HOM-HD-21 revealed two homologous motifs known as lectin domains with galactoside binding capacity. The two domains are linked by a stretch of about 30 amino acid residues and share a sequence homology of 39%. While the N-terminal lectin domain shows merely moderate homologies with known galectins, the C-terminal lectin domain is highly homologous to rat galectin-5 with an amino acid sequence identity of 70%. We ruled out mutations of the tumor-derived transcript by sequence comparison with the respective cDNA cloned from normal peripheral blood leukocytes. Recombinant protein expressed in Chinese hamster ovary cells was purified from lysates by lactose and galactose affinity chromatography, proving the galactoside binding capacity of this new galectin. Northern blot analysis revealed an expression spectrum restricted to peripheral blood leukocytes and lymphatic tissues. In accordance with the nomenclature of known galectins, we suggest to designate this novel galactoside binding protein galectin-9.

Amino Acid Sequence↗
PubMed1997

A testicular antigen aberrantly expressed in human cancers detected by autologous antibody screening.

Serological analysis of recombinant cDNA expression libraries (SEREX) using tumor mRNA and autologous patient serum provides a powerful approach to identify immunogenic tumor antigens. We have applied this methodology to a case of esophageal squamous cell carcinoma and identified several candidate tumor targets. One of these, NY-ESO-1, showed restricted mRNA expression in normal tissues, with high-level mRNA expression found only in testis and ovary tissues. Reverse transcription-PCR analysis showed NY-ESO-1 mRNA expression in a variable proportion of a wide array of human cancers, including melanoma, breast cancer, bladder cancer, prostate cancer, and hepatocellular carcinoma. NY-ESO-1 encodes a putative protein of Mr 17,995 having no homology with any known protein. The pattern of NY-ESO-1 expression indicates that it belongs to an expanding family of immunogenic testicular antigens that are aberrantly expressed in human cancers in a lineage-nonspecific fashion. These antigens, initially detected by either cytotoxic T cells (MAGE, BAGE, GAGE-1) or antibodies [HOM-MEL-40(SSX2), NY-ESO-1], represent a pool of antigenic targets for cancer vaccination.

Amino Acid Sequence↗
PubMed1997

The surgical management of incomplete testicular feminization syndrome in three sisters.

Three sisters with incomplete testicular feminization syndrome are presented. Most of the patients with this syndrome are females and surgery is an important part of their multidisciplinary treatment. Two of the sisters had gonadectomies, herniorrhaphies, vaginoplasty with neurovascular pudendal thigh flaps, reduction clitoroplasty and labia minora reconstruction. The third sister had sufficient vaginal depth and had release of an introitus skin web, clitoroplasty and labia minora reconstruction. All patients had a good result. The reconstructed vaginas are stable and sensate.

Adolescent↗
PubMed1997

Serological identification of human tumor antigens.

Using the antibody repertoire of cancer patients for the systematic search for human tumor antigens, a plenitude of new human tumor antigens has been identified demonstrating that many human tumors elicit multiple immune responses in the autologous host. The abundance of serologically defined human tumor antigens facilitates the identification of T cell dependent antigens and provides a basis for peptide and gene therapy vaccine strategies in a wide variety of human cancers.

Antigens, Neoplasm↗
PubMed1997

Serological analysis of human tumor antigens: molecular definition and implications.

Specific vaccines for the immunotherapy of human neoplasms require specific human tumor antigens. While efforts to identify such antigens by the analysis of the T-cell repertoire have yielded few antigens, the application of SEREX, the serological identification of antigens by recombinant expression cloning, has brought a cornucopia of new antigens. Several specific antigens have been identified in each tumor tested, suggesting that many human tumors elicit multiple immune responses in the autologous host. The frequency of human tumor antigens, which can be readily defined at the molecular level, facilitates the identification of T-cell-dependent antigens and provides a basis for peptide and gene-therapeutic vaccine strategies.

Antigen Presentation↗
PubMed1997

Translation initiation factor eIF-4gamma is encoded by an amplified gene and induces an immune response in squamous cell lung carcinoma.

Amplification of cellular oncogenes is an important mechanism of altered gene expression in human cancers. Using comparative genomic hybridization we recently identified an amplification at 3q26.1-q26.3 in 30% of squamous cell carcinomas of the lung. A variety of methods including microdissection-mediated procedures permit cloning of genes encoded within amplified domains but do not directly lead to the identification of biologically relevant genes. In this study, we have circumvented this problem by combining an immunological and molecular genetic approach to analyze squamous cell lung carcinoma. To identify both amplified and tumor relevant genes, we generated a cDNA expression library from a tumor with the 3q amplification and hybridized the expressed recombinant polypeptides with the autologous serum. Of 400000 cDNA clones we identified 17 antigens which induce an immune response in a patient with squamous cell lung carcinoma. While most clones represent individual genes sequence analysis revealed that four of the 17 cDNAs are nearly identical with the eukaryotic translation initiation factor (eIF)-4gamma recently assigned on 3q. We demonstrated that the gene for eIF-4gamma was amplified within 3q26-q27 in independent squamous cell lung carcinomas. In this study, we report the identification of several antigens which elicit an immune response in a squamous cell lung carcinoma patient including eIF-4gamma. eIF-4gamma is encoded by an amplified gene and possibly plays a crucial part in the development of squamous cell lung carcinoma.

Base Sequence↗
PubMed1996

The SSX-2 gene, which is involved in the t(X;18) translocation of synovial sarcomas, codes for the human tumor antigen HOM-MEL-40.

Using autologous serum for the serological analysis of recombinantly expressed clones (SEREX) from a cDNA derived from a human melanoma, several new melanoma antigens were identified that are immunogenic in the autologous host. Sequence analysis revealed that one of these antigens, HOM-MEL-40, was coded for by the SSX2 gene, which has recently been described to be involved in the t(X;18) translocation of human synovial sarcomas. Expression analysis performed by Northern blot and RT-PCR demonstrated the presence of HOM-MEL-40 transcripts in a significant proportion of human melanomas (50%), colon cancers (25 %), hepatocarcinomas (30%), and breast carcinoma (20%) but not in normal tissues except for testis. Sequence comparison with transcripts cloned from testis ruled out mutations in the melanoma-derived HOM-MEL-40. Antibodies against HOM-MEL-40 were found in 10 of 89 patients with melanoma, including 3 of 8 patients with HOM-MEL-40-positive tumors, but not in 41 apparently healthy controls. In view of the specific expression pattern and immunogenicity in cancer patients, HOM-MEL-40 holds promise as a target for immune interventions in a considerable population of patients with HOM-MEL-40-positive tumors.

Antigens, Neoplasm↗
PubMed1996

Cure of disseminated xenografted human Hodgkin's tumors by bispecific monoclonal antibodies and human T cells: the role of human T-cell subsets in a preclinical model.

Cure of a single established human Hodgkin's tumor growing subcutaneously in severe combined immunodeficient (SCID) mice can be achieved with a complex protocol using two bispecific monoclonal antibodies (Bi-MoAb) directed against the Hodgkin's associated CD30 antigen and the T-cell triggering molecules CD3 and CD28, respectively, together with human T cells prestimulated in vitro with Bi-MoAbs in the presence of CD30+ cells. To adapt this model to the clinical situation, disseminated tumors were established in SCID mice by intravenous injection of 2 x 10(7) cells of the Hodgkin's derived cell line L540CY. Treatment of SCID mice bearing disseminated CD30+ Hodgkin's tumors with the combination of CD3/CD30 and CD28/CD30 Bi-MoAbs and naive (ie, not in vitro prestimulated) human T cells resulted in the cure of all appropriately treated animals. T lymphocytes obtained from patients with advanced stage untreated Hodgkin's disease were as effective as lymphocytes from healthy controls. Treatment was effective even when delayed until 2 weeks after tumor inoculation, and application of Bi-MoAbs into SCID mice with circulating human T cells was as effective as injecting the Bi-MoAbs before the lymphocytes. Treatment results with isolated CD4+ and CD8+ human T cells suggest that both subsets are necessary for the Bi-MoAb mediated cure of xenografted human tumors in vivo. The efficacy and practicability of this preclinical immunotherapy protocol support and form the basis for the clinical evaluation of this approach in patients with Hodgkin's disease resistant to standard therapy.

Animals↗
PubMed1996

Interleukin-12 increases bispecific-antibody-mediated natural killer cell cytotoxicity against human tumors.

The combination of CD16/CD30 bispecific monoclonal antibodies (bi-mAb) and unstimulated human resting natural killer (NK) cells can cure about 50% of mice with severe combined immunodeficiency (SCID) bearing subcutaneously growing established Hodgkin's lymphoma. As interleukin-2 (IL-2) and IL-12 have been shown to increase NK cell activity, we tested the capacity of these cytokines to increase bi-mAb-mediated NK cell cytotoxicity against two types of human tumors (Hodgkin's disease and colorectal carcinoma). Unstimulated NK cells needed a three- to five-times higher antibody concentration than cytokine-stimulated NK cells to exert similar levels of bi-mAb-mediated cytotoxicity. The augmented tumor cell lysis was achieved with IL-12 at considerably lower concentrations than with IL-2 and was associated with a significantly increased bi-mAb-mediated intracellular Ca2+ mobilization. The efficiency of IL-12 in this setting together with its low toxicity make it the ideal candidate for a combination therapy with NK-cell-activating bi-mAb in human tumors that are resistant to standard treatment.

Antibodies, Bispecific↗
PubMed1996

Treatment of Hodgkin's disease with bispecific antibodies.

Bispecific monoclonal antibodies (Bi-MAbs) with dual specificity for tumor-associated antigens (TAA) and a triggering molecule of an immunologic effector cell, respectively, open the possibility to specifically target to and activate cytotoxic effector cells (macrophages, T-cells, NK cells) at the tumor site. Using appropriately designed Bi-MAbs and unstimulated human NK cells and T-cells, respectively, we were able to cure SCID mice xenografted with human Hodgkin's tumors. This approach was also effective in disseminated tumors and when treatment was delayed until three weeks after the inoculation of the tumor, thus establishing this approach as the most effective model of an immunomodulating therapy of human neoplasms. Early observations with an ongoing phase I/II study with CD16/CD30 Bi-MAb in patients with refractory Hodgkin's disease confirm the expected low toxicity. If these observations can be confirmed in larger clinical studies, effector cell activating Bi-MAbs could become an important weapon in the remaining fight for the conquest of Hodgkin's disease.

Animals↗
PubMed1996

H-plasty: a new modification for correction of nasal stenosis.

Unilateral complete nasal stenosis is a rare condition and is usually acquired. The alar wing and nasal vestibule may be disturbed because of stenosis. We operated on 2 patients with complete nasal stenosis by using the H-flap technique described in this paper. Anterior nares are formed by this technique and, in one case, we used a cartilage graft for creating symmetry of the alar wings. Functional and aesthetic anterior nares are obtained by this technique.

Cartilage↗
PubMed1995

Human neoplasms elicit multiple specific immune responses in the autologous host.

Expression of cDNA libraries from human melanoma, renal cancer, astrocytoma, and Hodgkin disease in Escherichia coli and screening for clones reactive with high-titer IgG antibodies in autologous patient serum lead to the discovery of at least four antigens with a restricted expression pattern in each tumor. Besides antigens known to elicit T-cell responses, such as MAGE-1 and tyrosinase, numerous additional antigens that were overexpressed or specifically expressed in tumors of the same type were identified. Sequence analyses suggest that many of these molecules, besides being the target of a specific immune response, might be of relevance for tumor growth. Antibodies to a given antigen were usually confined to patients with the same tumor type. The unexpected frequency of human tumor antigens, which can be readily defined at the molecular level by the serological analysis of autologous tumor cDNA expression cloning, indicates that human neoplasms elicit multiple specific immune responses in the autologous host and provides diagnostic and therapeutic approaches to human cancer.

Antibodies, Neoplasm↗
PubMed1995

The role of lymphocyte subsets and adhesion molecules in T cell-dependent cytotoxicity mediated by CD3 and CD28 bispecific monoclonal antibodies.

The cure of human Hodgkin's tumors heterotransplanted into SCID mice can be achieved by two bispecific monoclonal antibodies (Bi-mAb) directed against the tumor-associated CD30 antigen and CD3 and CD28, respectively, and normal peripheral human blood T cells. We investigated the role of lymphocyte subsets and adhesion molecules in this Bi-mAb-mediated cytolysis. CD4+ lymphocytes were the most rapidly expanding subpopulation, but Bi-mAb-directed cytotoxicity was mediated preferentially by CD8+ lymphocytes and effector cells belonging to the CD45RO+ "memory" pool. Blocking of the LFA-1/ICAM-1 or CD2/LFA-3 adhesion pathways by mAb decreased Bi-mAb-mediated cytotoxicity. This was not due to inhibition of aggregate formation between Bi-mAb-coated T lymphocytes and target cells. Cross-linking of LFA-1 or CD2 molecules on lymphocytes prestimulated with Bi-mAb bound to CD3 and CD28 antigen lead to a more pronounced and prolonged rise in the intracellular concentration of free Ca2+. Additional CD2 cross-linking resulted in the tyrosine phosphorylation of distinct proteins. These findings indicate that adhesion molecules play a critical role and function as co-stimulatory signals rather than as cellular contact mediators in CD3 and CD28 Bi-mAb-stimulated T lymphocytes.

Antibodies, Bispecific↗
PubMed1995

[Intracerebral hemorrhage and multiple brain abscesses caused by Bacillus cereus within the scope of acute lymphatic leukemia].

Multiple hematogenic brain abscesses in immunosuppression are occasionally caused by rare and primary apathogenic causative agents. We report a first case of an isolated CNS infection by Bacillus cereus, which led to death from multiple brain abscesses and an intracerebral hemorrhage, probably caused by the infection, within 4 days. The underlying disease leading to immunosuppression was acute lymphatic leukemia in complete remission. In spite of antibiotic therapy the chemotherapy-induced neutropenia enabled unhindered spreading of the necrotizing infection, which was verified by histological analysis. The production of potent toxins such as hemolysin and cerelolysin by B. cereus leads to rapid and fulminant tissue destruction usually involving the walls of blood vessels.

Adult↗
PubMed1994

Cure of xenografted human tumors by bispecific monoclonal antibodies and human T cells.

Tumor immunotherapy should increase both the number of T cells that kill the tumor and the likelihood that those cells are activated at the tumor site. Bispecific monoclonal antibodies (Bi-mAbs) were designed that bound to a Hodgkin's tumor-associated antigen (CD30) on the tumor and to either CD3 or CD28 on the T cell. Immunodeficient mice were cured of established human tumors when mice were treated with both the CD3-CD30 and the CD28-CD30 Bi-mAbs and then given human peripheral blood lymphocytes that had been incubated with the CD3-CD30 Bi-mAb and cells that expressed CD30. The enrichment of human T cells within the tumor and the fact that established tumors can be cured may indicate in situ activation of both the T cell receptor and the costimulatory pathway.

Animals↗
PubMed1994

Opposite effects of the CD30 ligand are not due to CD30 mutations: results from cDNA cloning and sequence comparison of the CD30 antigen from different sources.

CD30L, the ligand for the activation antigen CD30, is a member of the tumor necrosis factor family of cytokines. Binding of CD30L to CD30, which is a member of the nerve growth factor/tumor necrosis factor receptor family, induces proliferation in peripheral blood lymphocytes and Hodgkin's derived cell lines with a T-cell phenotype such as HDLM-2 and L540, while cell lines derived from anaplastic large cell lymphomas, such as Karpas 299, undergo cell death. In order to investigate whether mutations of the CD30 antigen are responsible for these opposite effects, we cloned the open reading frame of CD30 cDNAs from the cell lines L540 and Karpas 299 and from peripheral blood lymphocytes by reverse transcriptase polymerase chain reaction. Sequencing of independent plasmid clones revealed that these cells have a silent transition (A-->G) at position 771 of the open reading frame compared to the published sequence derived from the HTLV-1+ cell line HUT-102. As published data have shown that crosslinking of CD30 induces an elevation of cytosolic free calcium ([Ca2+]i) in TCR positive Jurkat cells, we have analysed the effect of crosslinking of CD30 on L540 and Karpas 299 cells. No elevations of [Ca2+]i have been observed in these cell lines after crosslinking of CD30 with HRS-4. We conclude (i) that the different functional effects of CD30 in PBL, L540 and Karpas 299 are not due to differences in the primary structure of the receptor; and (ii) that the different responses observed upon engagement with CD30L for the cell lines L540 and Karpas 299 do not correlate with differences in mobilization of [Ca2+]i after crosslinking of CD30.

Base Sequence↗