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  • 2003  (9)
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  • 2003  (9)
  • 1
    Language: English
    In: Trends in Microbiology, 2003, Vol.11(4), pp.171-178
    Description: Human cytomegalovirus (HCMV) retinitis frequently occurs in severely naturally and iatrogenically immunocompromised patients. It has been shown that the immune-privileged retinal pigment epithelium (RPE) is a major site of persistent HCMV. Recently, evidence has accumulated to show that HCMV immediate early (IE) gene expression in RPE cells deviates ocular antiviral inflammation via FasL. Moreover, unlike in other cell types, the HCMV major IE1/2 enhancer promoter (MIEP) resists activation by proinflammatory stimuli mediated by the transcription factor NF- Kappa B. However, tumor necrosis factor- alpha (TNF- alpha ) and interferon- gamma (IFN- gamma ) found at elevated levels in transplant recipients and AIDS patients with retinitis sensitize RPE cells and other retinal cells to FasL-mediated apoptosis, thus contributing to retina destruction and necrosis rather than inflammation. These specific features of RPE cells in conjunction with deregulated immune responses of immunocompromised patients seem to contribute to virus persistence and pathogenesis within the immune-privileged ocular retina.
    Keywords: Biology
    ISSN: 0966-842X
    E-ISSN: 1878-4380
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  • 2
    Language: English
    In: Cancer research, 01 April 2003, Vol.63(7), pp.1508-14
    Description: Replication restricted oncolytic viruses such as multimutated herpes simplex virus type 1 (HSV-1) G207 represent a novel and attractive approach for cancer therapy, including pediatric solid tumors. Rhabdomyosarcoma is the most common soft-tissue sarcoma of childhood and is often diagnosed already as an advanced disseminated disease. Despite aggressive therapeutic approaches, the prognosis for patients with metastatic rhabdomyosarcoma remains grim. Therefore, there is a need for novel effective drugs with superior safety and efficacy profile. In this study, we showed marked in vitro activity of HSV-1 G207 against embryonal and alveolar rhabdomyosarcoma cells. All human embryonal (KF-RMS-1, RD, and CCA) and alveolar RMS (KFR, Rh28, Rh30, and Rh41) cell lines were highly sensitive to cytotoxic and replicative effects of G207 even at a multiplicity of infection of 0.01, except embryonal Rh1 rhabdomyosarcoma cells, which were efficiently killed only upon multiplicity of infection of 1.0. i.v. G207 treatment of xenotransplanted KFR and KF-RMS-1 tumors in mice led to significant tumor growth inhibition of both tumor entities, whereas intraneoplastic G207 treatment additionally resulted in complete tumor disappearance in 25% of animals. No difference has been found between alveolar and embryonal types of rhabdomyosarcoma. Combination treatment of both cell lines with G207 and vincristine led to strongly enhanced in vitro cytotoxicity without affecting infection efficiency and replication of G207 in KFR as well as in KF-RMS-1 cells. In vivo combination treatment using i.v. G207 and vincristine resulted in complete regression of alveolar rhabdomyosarcoma in five of eight animals and significant growth inhibition of embryonal rhabdomyosarcoma. Taking into consideration the proven safety of G207 in humans, we suggest that G207 alone and in combination with vincristine should be additionally evaluated as a potential agent against human rhabdomyosarcoma.
    Keywords: Antineoplastic Agents, Phytogenic -- Pharmacology ; Rhabdomyosarcoma -- Therapy ; Simplexvirus -- Physiology ; Vincristine -- Pharmacology
    ISSN: 0008-5472
    E-ISSN: 15387445
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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  • 3
    Language: English
    In: International Journal of Cancer, 10 March 2003, Vol.104(1), pp.36-43
    Description: Cytotoxic drug treatment of neuroblastoma often leads to the development of drug resistance and may be associated with increased malignancy. To study the effects of long‐term cytotoxic treatment on malignant properties of tumor cells, we established 2 neuroblastoma cell sublines resistant to vincristine (VCR) and doxorubicin (DOX). Both established cell lines (UKF‐NB‐2VCR and UKF‐NB‐2DOX) were highly resistant to VCR, DOX and vice‐versa but retained their sensitivity to cisplatin. UKF‐NB‐2VCR and UKF‐NB‐2DOX expressed significant amounts of P‐glycoprotein, while parental cells were P‐glycoprotein negative. GD2 expression was upregulated, whereas NCAM expression was decreased in both resistant cells. Spectral karyotype (SKY) analysis revealed complex aberrant karyotypes in all cell lines and additional acquired karyotype changes in both resistant cells. All cell lines harbored high levels of N‐myc amplification. Compared to parental cells, UKF‐NB‐2VCR and UKF‐NB‐2DOX exhibited more than 2‐fold increase in clonal growth , accelerated adhesion and transendothelial penetration and higher tumorigenicity . We conclude that development of drug resistance and acquisition of certain karyotypic alterations is associated with an increase of additional malignant properties that may contribute to the poor prognosis in advanced forms of NB. The 2 novel neuroblastoma cell sublines also provide useful models for the study of drug resistance in aggressive forms of neuroblastoma. © 2002 Wiley‐Liss, Inc.
    Keywords: Neuroblastoma ; Drug Resistance ; Mdr‐1 ; Ncam ; Gd2 ; Karyotype
    ISSN: 0020-7136
    E-ISSN: 1097-0215
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  • 4
    In: The New England Journal of Medicine, 2003, Vol.348(20), pp.1967-1976
    Description: Background The severe acute respiratory syndrome (SARS) has recently been identified as a new clinical entity. SARS is thought to be caused by an unknown infectious agent. Methods Clinical specimens from patients with SARS were searched for unknown viruses with the use of cell cultures and molecular techniques. Results A novel coronavirus was identified in patients with SARS. The virus was isolated in cell culture, and a sequence 300 nucleotides in length was obtained by a polymerase-chain-reaction (PCR)–based random-amplification procedure. Genetic characterization indicated that the virus is only distantly related to known coronaviruses (identical in 50 to 60 percent of the nucleotide sequence). On the basis of the obtained sequence, conventional and real-time PCR assays for specific and sensitive detection of the novel virus were established. Virus was detected in a variety of clinical specimens from patients with SARS but not in controls. High concentrations of viral RNA of up to 100 million molecules per milliliter were found in sputum. Viral RNA was also detected at extremely low concentrations in plasma during the acute phase and in feces during the late convalescent phase. Infected patients showed seroconversion on the Vero cells in which the virus was isolated. Conclusions The novel coronavirus might have a role in causing SARS. This study used cell culture and molecular techniques to identify the infectious agent associated with SARS. A novel coronavirus was found in multiple samples from 18 patients but in no specimens from control subjects. In the patients there were high concentrations of viral RNA in sputum, a finding consistent with a highly infectious agent. Low concentrations of viral RNA were also detected in stool. The severe acute respiratory syndrome (SARS) was recently identified as a new clinical entity.1,2 Patients present with fever, dry cough, dyspnea, headache, and hypoxemia. Typical laboratory findings are lymphopenia and mildly elevated aminotransferase levels. Death may result from progressive respiratory failure due to alveolar damage.3 SARS appears to be caused by an unknown infectious agent that is transmitted from human to human. The World Health Organization (WHO) had recorded 2353 cases by April 4, 2003. About 4 percent of patients with SARS have died.4 The SARS epidemic started in Asia, with the majority of cases occurring in China and . . .
    Keywords: Adult–Genetics ; Amino Acid Sequence–Analysis ; Animals–Analysis ; Base Sequence–Blood ; Cattle–Classification ; Coronavirus–Genetics ; DNA, Viral–Isolation & Purification ; Disease Outbreaks–Epidemiology ; Female–Virology ; Humans–Virology ; Male–Virology ; Molecular Sequence Data–Virology ; Phylogeny–Virology ; Polymerase Chain Reaction–Virology ; RNA, Viral–Virology ; RNA, Viral–Virology ; Sars Virus–Virology ; Sars Virus–Virology ; Sars Virus–Virology ; Sequence Homology, Nucleic Acid–Virology ; Severe Acute Respiratory Syndrome–Virology ; Severe Acute Respiratory Syndrome–Virology ; Sputum–Virology ; Singapore ; Germany ; Asia ; Proteins ; Headaches ; Fever ; Patients ; Laboratories ; DNA, Viral ; RNA, Viral ; World Health Organization;
    ISSN: 0028-4793
    E-ISSN: 1533-4406
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  • 5
    In: Transplantation, 2003, Vol.76(12), pp.1735-1741
    Description: BACKGROUND. : The immunosuppressive drug mycophenolate mofetil (MMF) reduces expression of the heterophilic binding elements intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 and thereby prevents attachment of alloactivated leukocytes to donor endothelium. The authors speculated that MMF might further diminish receptors of the immunoglobulin superfamily which, however, act as homophilic binding elements. Because decrease of homophilic adhesion receptors correlates with tumor dissemination and metastasis, MMF could trigger development or recurrence of neoplastic tumors. METHODS. : The authors analyzed the influence of MMF on homotypic adhesion receptors and its consequence for tumor cell attachment to an endothelial cell monolayer. Neuroblastoma (NB) cells, which self-aggregate by means of the homophilic-binding element neural cell adhesion molecule (NCAM), were used. Effects of MMF on the 140- and 180-kDa NCAM isoforms were investigated quantitatively by flow cytometry, Western blot, and reverse-transcriptase (RT) polymerase chain reaction (PCR). The relevance of NCAM for tumor cell binding was proven by treating NB with NCAM antisense oligonucleotides. RESULTS. : MMF profoundly increased the number of adherent NB cells, with a maximum effect at 0.1 μM, compared with controls. Decrease of NCAM on the cell surface was detected by flow cytometry. Western blot and RT-PCR demonstrated reduced protein and RNA levels of the 140- and 180-kDa isoforms. Treatment of NB cells with NCAM antisense oligonucleotides showed that reduced NCAM expression leads to enhanced tumor cell adhesion. CONCLUSIONS. : MMF decreases NCAM receptors, which is associated with enhanced tumor cell invasiveness. The authors conclude that an MMF-based immunosuppressive regimen might increase the risk of tumor metastasis if this process is predominantly conveyed by means of homophilic adhesion proteins.
    Keywords: Mycophenolate Mofetil ; Cell Adhesion ; Immunosuppression ; Tumor Cells ; Intercellular Adhesion Molecule 1 ; Vascular Cell Adhesion Molecule 1 ; Leukocytes ; Endothelium ; Neural Cell Adhesion Molecule ; Neuroblastoma Cells ; Clinical ; Man ; Man;
    ISSN: 0041-1337
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  • 6
    Language: English
    In: International Journal of Molecular Medicine, June 2003, Vol.11(6), pp.743-747
    Description: The human T-lymphoid cell line H9 resistant to 3'-azido-2',3'-dideoxythymidine (AZT) has a very low level of thymidine kinase (TK) expression which accounts for the failure of AZT to inhibit HIV-1 replication. In the present study DNA methylation and histone deacetylation as possible mechanisms of decreased TK gene expression in the resistant cells were investigated. The resistant cells expressed high levels of DNA methyltransferases (DNMTs) 3a and 3b. The DNA methylation inhibitor, 5-aza-cytidine (5-aza-C), increased TK gene expression and antiviral activity of AZT in the resistant cells, while histone deacetylase inhibitor trichostatin A (TSA) had no effect. The results suggest that hypermethylation of the TK gene but not histone deacetylation in AZT-resistant H9 cells accounts for decreased TK gene expression and failure of AZT to inhibit HIV-1 replication probably due to overexpression of DNMT 3a and 3b.
    ISSN: 1107-3756
    Source: Spandidios Publications (Spandidos Publications Ltd.)
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  • 7
    Language: English
    In: International journal of molecular medicine, June 2003, Vol.11(6), pp.743-7
    Description: The human T-lymphoid cell line H9 resistant to 3'-azido-2',3'-dideoxythymidine (AZT) has a very low level of thymidine kinase (TK) expression which accounts for the failure of AZT to inhibit HIV-1 replication. In the present study DNA methylation and histone deacetylation as possible mechanisms of decreased TK gene expression in the resistant cells were investigated. The resistant cells expressed high levels of DNA methyltransferases (DNMTs) 3a and 3b. The DNA methylation inhibitor, 5-aza-cytidine (5-aza-C), increased TK gene expression and antiviral activity of AZT in the resistant cells, while histone deacetylase inhibitor trichostatin A (TSA) had no effect. The results suggest that hypermethylation of the TK gene but not histone deacetylation in AZT-resistant H9 cells accounts for decreased TK gene expression and failure of AZT to inhibit HIV-1 replication probably due to overexpression of DNMT 3a and 3b.
    Keywords: Anti-HIV Agents -- Pharmacology ; T-Lymphocytes -- Drug Effects ; Zidovudine -- Pharmacology
    ISSN: 1107-3756
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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  • 8
    In: International Journal of Molecular Medicine, 06/01/2003
    ISSN: 1107-3756
    E-ISSN: 1791-244X
    Source: CrossRef
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  • 9
    Language: English
    In: International Journal of Colorectal Disease, 2003, Vol.18(4), pp.292-299
    Description: The prognostic relevance of sialyl Lewis X (sLeX) expression in colorectal and gastric cancer and its relevance to the hematogenous phase of tumor invasion is controversial. This study was designed to evaluate sLeX expression during tumor cell-endothelial cell interaction in vitro. Adhesion and transendothelial penetration of MKN45, PaCa-2, WiDr, or Dan-G cells was analyzed by combined phase contrast-reflection interference contrast microscopy. In parallel, kinetics of membranous sLeX expression were examined fluorimetrically. To identify factor(s) which may be responsible for sLeX expression during tumor invasion tumor cells were treated with soluble immunomodulators, isolated endothelial plasma membranes, or E-selectin or P-selectin IgG fusion proteins. sLeX was then analyzed by flow cytometry. Fluorometric quantification of sLeX demonstrated an inverse correlation between basal sLeX expression level and adhesion capacity of the tumor cells. Unexpectedly, sLeX was strongly down-regulated on tumor cell membranes in the course of heterophilic cell-cell contacts. The process occurred transiently, with a maximum effect 30–60 min after introducing tumor cells to the endothelial monolayer. Binding of tumor cells to immobilized E- and P-selectin IgG globulin chimeras was shown to be responsible for this phenomenon. A transient loss of sLeX is necessary for gastrointestinal tumor cells to invade endothelial cells. Due to the transient nature of the decrease in sLeX the controversy about the prognostic relevance of sLeX expression in colorectal and gastric cancer may be rooted in the stage of tumor invasion at the time of sLeX measurement.
    Keywords: Adhesion E-selectin Gastrointestinal tumor P-selectin Sialyl Lewis X
    ISSN: 0179-1958
    E-ISSN: 1432-1262
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