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  • 2010-2014
  • 1995-1999  (172)
  • 1925-1929
  • 1900-1904
  • 1999  (172)
  • Apoptosis  (93)
  • gene expression  (79)
Material
Years
  • 2010-2014
  • 1995-1999  (172)
  • 1925-1929
  • 1900-1904
Year
  • 1
    ISSN: 1534-4681
    Keywords: Gemcitabine ; bcl-2 ; Pancreatic cancer ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Gemcitabine is a new nucleoside analogue that produces a clinical response in 30% of patients with unresectable pancreatic carcinoma. The cytotoxic effects of many chemotherapeutic agents occur through induction of programmed cell death (apoptosis), which is controlled by the bcl-2 gene family. We determined whether induction of apoptosis by gemcitabine in pancreatic carcinoma is associated with cellular Bcl-2 content. Methods: Four pancreatic carcinoma cell lines (MIA-PaCa-2, AsPC-1, Panc-1, and Panc-48) were screened by Western blotting for Bcl-2 protein expression. Dose-response relationships for the cytotoxic effects of gemcitabine were determined using methylthiotetrazole assays, and induction of apoptosis was confirmed by fluorescence-activated cell sorting analysis. MIA-PaCa-2 cells transfected with human bcl-2 were also analyzed for gemcitabine-induced apoptosis. Results: Pancreatic cancer cell lines expressed varying amounts of Bcl-2, and the 50% lethal dose for gemcitabine-induced apoptosis was correlated with Bcl-2 content. Furthermore, Bcl-2 overexpression was associated with a significant increase in the 50% lethal dose for gemcitabine-induced apoptosis. Conclusions: Cellular Bcl-2 content was directly correlated with the cytotoxicity of gemcitabine in pancreatic carcinoma. Therefore, routine immunohistochemical analyses may be useful in predicting gemcitabine efficacy, and patients who would likely not benefit could be spared gemcitabine administration. Furthermore, the effectiveness of gemcitabine and other chemotherapeutic agents may be increased by gene therapy-mediated alteration of bcl-2 gene family members.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 77 (1999), S. 189-192 
    ISSN: 1432-1440
    Keywords: Key words Thyroid ; Cell culture ; Retinoids ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Retinoids influence proliferation and differentiation in transformed thyroid cell lines. Retinoids are able to damage cells by destabilizing lysosomal membranes and induce apoptosis in certain cell lines. In normal thyrocytes retinol modulates iodine metabolism. At concentrations higher than 50×10–6 M retinoids are cytotoxic for normal (not transformed) thyroid cells. The mechanism of this cytotoxicity is unknown. We studied the effect of 7–80×10–6 M retinol on porcine follicular thyrocytes in culture. In order to differentiate between membrane-destabilizing effects and apoptosis we investigated cultures after incubation with retinol by light- and electron-microscopy and by labeling of potential nicks in the DNA helix by terminal deoxynucleotidyltransferase-dUTP mediated DNA nick end labeling. We conclude that the observed cytotoxicity is caused mainly by the induction of apoptosis.
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  • 3
    ISSN: 1432-1440
    Keywords: Key words Chronic lymphocytic leukemia ; Apoptosis ; Cell growth ; Signaling ; Review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Chronic lymphocytic leukemia is a malignant disease characterized by clonal expansion of relatively mature B-lymphocytes with a high percentage of cells arrested in the nonproliferative G0/G1 cell cycle phase. Possibly reflecting the clinical heterogeneity observed in patients, various signaling pathways may become affected during the initiation and course of this disease. This review discusses frequent alterations concerning proliferative, differentiation-inducing, and apoptotic pathways elucidated in the recent years that have improved our understanding of this disease.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cancer research and clinical oncology 125 (1999), S. 1-8 
    ISSN: 1432-1335
    Keywords: Key words Cell proliferation ; Apoptosis ; Cell death ; Cultured cells ; Hepatocellular carcinoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract There are conflicting results for experiments aimed at determining whether anticancer drug therapy of human hepatocellular carcinoma prolongs the survival rate effectively. The purpose of this study was to assess the effect of low concentrations of doxorubicin, mitomycin C, and ethanol on cell replication (cell number and proliferation), and cell apoptosis of cultured human hepatocellular carcinoma (Hep-G2) cells. After 1 day of exposure doxorubicin inhibited cell replication initially by 72%, but a partial recovery of the cell number was observed. Mitomycin C inhibited to the same extent but without recovery. Ethanol reduced the cell number even further, the maximum inhibition (12 days after exposure) being 96.4%. After 3 days of exposure all three agents stopped cell replication at a level of 2%–4% of the control (P 〈 0.001). Cell apoptosis was activated most strikingly by mitomycin C (5 μg/ml) after 1 day of exposure and by ethanol (150 μl/ml) after 3 days of exposure. Two-way repeated-measures analysis of variance showed statistically significant differences, with ethanol being the most significant followed by mitomycin C doxorubicin, and the control (P 〈 0.01). Thus, a low dose of ethanol combined with an exposure time of up to 3 days appears to be an effective regimen to control growth of human hepatocellular carcinoma cells in vitro. The strong induction of apoptosis by ethanol might be of additional benefit for a local application in vivo.
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  • 5
    ISSN: 1432-1335
    Keywords: Key words Basic fibroblast growth factor ; Cisplatinum ; Apoptosis ; Bcl-2 ; MCF-7
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Basic fibroblast growth factor (bFGF) is a classical mitogen in fibroblasts and endothelial cells. Our previous studies have demonstrated that bFGF inhibits the growth of MCF-7 human breast cancer cells. The aim of the present study was to examine the effect of bFGF on cis-diamminedichloroplatinum(cisplatin)-induced cytotoxicity in MCF-7 breast cancer cells as compared to normal endothelial cells. MCF-7/NCF cells transduced with a vector expressing the bFGF gene and overexpressing its product, and MCF-7/N2 cells transduced with the backbone vector were incubated with a combination of bFGF and cisplatin for 5 days; results were compared with those obtained with bovine aortic endothelial cells. Cell proliferation was assessed with the sulforhodamine B colorimetric cytotoxicity assay. Apoptosis was quantitatively determined by flow-cytometric analysis for DNA damage and the apoptotic death assay for DNA fragmentation, and qualitatively by electron microscopy. Reverse transcriptase/polymerase chain reaction analysis and an enzyme immunoassay were used to determine the mRNA and protein level, respectively, of the anti-apoptotic bcl-2 gene product. We found that bFGF enhanced cisplatin-induced cytotoxicity in MCF-7 breast cancer sublines. bFGF enhanced proliferation of normal endothelial cells and did not increase cisplatin-induced cytotoxicity. This effect was accompanied by down-regulation of the anti-apoptotic protooncogene bcl-2 and the enhancement of cisplatin-induced apoptosis. We suggest that the improved understanding of the role of bFGF in the differential modulation of the response of breast cancer and normal endothelial cells to chemotherapy may enable active intervention to alter the therapeutic ratio favorably in breast cancer patients.
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  • 6
    ISSN: 1432-1335
    Keywords: Keywords Chemosensitivity ; Human gastric carcinoma ; Micrometastasis ; Apoptosis ; Circulating tumor cells ; Fluoropyrimidine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Antimetastatic effects of 5-FU and its derivative, 1-hexylcarbamoyl-5-fluorouracil (HCFU) on human gastric cancer micrometastasis and their mode of action were evaluated, using a spontaneous lung metastasis model (HY-1) in nude mice. Metastases were first detected in the lung from 4 weeks after subcutaneous transplantation, growing intravascularly and forming micrometastases at 100% incidence by 6 weeks after implantation. Lung metastasis in mice bearing subcutaneous tumors was significantly inhibited by HCFU at doses of 100–150 mg kg−1 day−1 without severe toxic side-effects, when orally administered three times per week either from week 4 or week 6 to 9 weeks after implantation. Spontaneous lung metastasis was also inhibited by the administration of 5-FU, but to lesser extent than with HCFU at equimolar low doses. Apoptosis within primary tumors and lung metastatic foci, as detected by the terminal-deoxynucleotidyltransferase-mediated dUTP nick-end labeling method, was found to be significantly enhanced by HCFU as well as 5-FU administration at doses of more than 100 mg kg−1 day−1 and 50 mg kg−1 day−1 respectively. However, proliferating activity of the metastatic foci, as evaluated by MIB-1 immunostaining, was not significantly suppressed by HCFU or 5-FU treatment. Furthermore, polymerase chain reaction analysis using human specific primers for the β-globin gene, which proved to be capable of detecting 10 tumor cells/ml mouse blood, revealed that circulating tumor cells in the peripheral blood of mice bearing primary tumors were reduced by HCFU or 5-FU administration. These results indicate that circulating tumor cells in blood and micrometastases in the lung are sensitive to these chemotherapeutic agents, and suggest that the anti-metastatic effect of these agents is mediated, at least in part, by enhanced apoptosis rather than by inhibition of cell proliferation.
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  • 7
    ISSN: 1432-1335
    Keywords: Key wordsIGF ; Apoptosis ; Transformation ; Chemosensitivity ; Signaling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Insulin-like growth factor I (IGF-I) exerts pleiotropic effects on mammalian cells via stimulation of its receptor (IGF-IR), a receptor tyrosine kinase. In vivo, IGF-I acts both as a local tissue growth factor and as a circulating hormone. In oncological research, IGF-I has received increased attention as the activated IGF-I/IGF-IR system displays mitogeneic, transforming, and anti-apoptotic properties in various cell types by stimulating distinct intracellular signaling pathways. Recent data suggest that the anti-apoptotic effect of IGF-I may mediate decreased sensitivity to chemotherapeutic drugs in vitro and in vivo. Thus, targeting the IGF-I/IGF-IR system could serve as an approach to overcome clinical drug resistance in certain tumors.
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  • 8
    ISSN: 1432-1335
    Keywords: Key words Immunohistochemistry ; DNA repair ; Radiation-inducible response ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Immunohistochemical methods were used to determine abundance and subnuclear distribution of DNA topoisomerase I and the Bax protein in normal and excision-repair-deficient xeroderma pigmentosum (XP) fibroblasts after irradiation of cells with γ rays or UV light, or exposure to the topoisomerase I inhibitor topotecan. DNA topoisomerase I and Bax were monitored using antisera raised against the human proteins. In addition, topoisomerases IIα and IIβ were made visible with specific antibodies. In untreated cells, DNA topoisomerase I was found to occur in the cytoplasm and in nucleoli. Irradiation with γ rays (2–12 Gy) or UV light (0.3–1.2 mW/cm2) changed the staining pattern in nuclei such that a multitude of small topoisomerase-I-rich centers occurred, which were evenly distributed over the karyoplasm. Simultaneously nucleoli disintegrated. Treatment of fibroblasts with topotecan (6–100 μM concentrations) resulted in similar alterations although the changes were much more pronounced. Combinations of topotecan and γ irradiation caused additive effects. We conclude that the increase in the number of topoisomerase-I-positive spots and the high fluorescence intensity of the latter may reflect three biological processes: (i) enhanced transcriptional activity (e.g. of DNA damage response genes), (ii) tagging of damaged DNA sites for repair, or (iii) initiation of apoptosis. In separate assays using normal and XP cells, a dose-dependent increase in protein reacting with Bax antibody was observed in nuclei, following treatment with γ rays or topotecan. In addition, topotecan induced a netlike arrangement of this Bax protein in nuclei. The meshes of the net structure resembled vesicles. DNA staining with 4′,6-diamidino-2-phenylindole dihydrochloride revealed that the vesicle-type structures contained DNA. Upon further incubation with topotecan, cells showing the netlike Bax arrangement eventually died. We conclude that topotecan-induced changes made visible by nuclear Bax protein are associated with apoptosis. XP cells, when treated with topotecan, responded more readily than normal cells with both an increase in nuclear Bax protein and rearrangement of Bax, indicating that UV repair functions may be required to process DNA damage inflicted by topotecan. Monitoring of DNA topoisomerases IIα and IIβ in γ-irradiated cells with antibodies revealed a dramatic increase in the IIα form and a redistribution of the IIβ form representing fragmentation of nucleoli.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cancer research and clinical oncology 125 (1999), S. 357-360 
    ISSN: 1432-1335
    Keywords: Key words Colorectal neoplasms ; Apoptosis ; Chemosensitivity ; p53 gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose : The p53 gene is considered one of the most important in the control of apoptosis, and its mutations have a close relationship with chemosensitivity. The aim of this work was to investigate the role of p53 in the apoptosis of colorectal cancer cells in vitro, induced by 5-fluorouracil (5-FU) and hydroxy-camptothecin (HCPT). Methods : A total of 39 colorectal cancer samples from patients were treated in vitro with 5-FU (10 μg/ml), 5-FU (10 μg/ml) + leucovorin (5 μg/ml), HCPT (0.1 μg/ml) and HCPT (0.1 μg/ml) + Salvia mitorrhiza (6 μl), using an in situ terminal deoxynucleotidyltransferase assay to detect chemosensitivity. p53 gene mutations from tumor DNA were detected, after amplification by the polymerase chain reaction of exons 5–8, by non-radioactive single-strand conformation polymorphism. Results : p53 gene mutations were observed in 43.6% (17/39) of colorectal carcinomas, when the terminal deoxynucleotidyltransferase assay was used to detect the tumor apoptotic rate. Cells with mutated p53 had lower chemosensitivity than those without (p 〈 0.01). Conclusion : Routine assessment of p53 status may be helpful in selecting patients with the wild-type p53 gene, who have a predictably better response to chemotherapy.
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  • 10
    ISSN: 1432-1335
    Keywords: Key words EGF receptor signalling ; Tyrphostin ; Apoptosis ; Colon cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Growth effects of tyrphostins A25 and AG1478 on colorectal tumor cells were studied to explore therapeutic potential. Cell number, DNA synthesis and apoptotic index were measured as growth parameters and cell-death-associated proteins Bcl-2 and Bak and protein phosphorylation were analyzed. Both tyrphostins inhibited DNA synthesis and induced apoptosis in tumor cell cultures with different patterns of activity. A25 displayed strong selectivity for the cell lines expressing high levels of epidermal growth factor (EGF), HT29/HI1 and SW480. Inhibition of DNA synthesis was efficient in all cells except T84, and the apoptotic index increased two- to fivefold. By contrast, AG1478 was highly effective in all cell lines. In addition, it caused cell loss in VACO235 adenoma cells at concentrations lower than those necessary to inhibit BrdU incorporation, reflecting preferential retention of cells actively synthesizing DNA. Induction of apoptosis was more efficient with AG1478 than with A25 (tenfold in VACO235). Insulin-like growth factor (IGF1) did not rescue cells exposed to A25 or to high concentrations of AG1478, but was effective with suboptimal amounts of AG1478. Both compounds inhibited phosphorylation of the EGF receptor as well as additional proteins. AG1478 induced expression of Bak and down-regulated Bcl-2. In summary, tyrphostins may provide alternatives for colorectal tumor treatment. Their broader range of activities and the lower susceptibility to interactions with IGF1 can be an advantage over receptor antibodies.
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  • 11
    ISSN: 1432-1335
    Keywords: Key words Experimental pancreatic cancer ; Hormonal therapy ; Bombesin antagonist ; Somatostatin analog ; LH-RH antagonist ; EGF receptor ; Apoptosis ; AgNOR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Reduction in receptors for epidermal growth factor (EGF) in cancers appears to be one of the principal mechanisms through which peptide hormone analogs can inhibit tumor growth. In this study, hamsters with nitrosamine-induced pancreatic cancers were treated for 8 weeks with bombesin/gastrin-releasing peptide (GRP) antagonist RC-3095, somatostatin analog RC-160 or the luteinizing hormone-releasing hormone antagonist Cetrorelix, using sustained delivery systems releasing 20, 35 and 20 μg analog/ day respectively. To establish the pattern of changes in the number and affinity of EGF receptors on tumors, groups of animals were sacrificed at regular intervals during therapy. Chronic treatment with RC-3095 or Cetrorelix resulted in an early (day 10) and sustained reduction (71% or 69% respectively) in EGF receptors on pancreatic tumors. In contrast, RC-160 decreased receptor concentration by 60% only after 20 days. Among the histological characteristics of proliferation, the decrease in argyrophilic nucleolar organizer regions, but not apoptotic and mitotic indices, showed a correlation with the fall in EGF receptors. The concentration of the receptors returned to the control level 4 days after cessation of chronic treatment with RC-3095. The effect of single injections of RC-3095, RC-160 and Cetrorelix on EGF receptors was also investigated. RC-160 decreased the number of EGF receptors on pancreatic cancers by 31% 3 h after administration, but the receptors had returned to normal level at 6 h. RC-3095 and Cetrorelix caused a 67% and 59% decline, respectively, in EGF receptors only 6 h after injection and the concentration of receptors remained low for 24 h. Thus, the pattern of down-regulation of EGF receptors in pancreatic cancers appears to depend on the peptide used for therapy. Since the antitumor effect may be the result of the fall in EGF receptors in cancers, information on the time course of changes in these receptors during treatment with these analogs may lead to an improvement in therapeutic regimens.
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  • 12
    ISSN: 1433-0474
    Keywords: Schlüsselwörter Ataxia teleangiectatica ; Immunfunktionsstörung ; Lymphozytensubpopulationen ; Apoptose ; CD45RO ; CD45RA ; Key words Ataxia teleangiectasia ; Immunodeficiency ; Lymphocyte subset ; Apoptosis ; CD45RO ; CD45RA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Background: Can a characterisation of the lymphocyte subset in patients with ataxia teleangiectasia offer an explanation for the cellular defect of their immunfunction? Methods: In ten patients with ataxia teleangiectasia and a corresponding control group of individuals of similar age and sex, immunophenotyping was carried out by means of flow cytometric analysis and the use of monoclonal antibodies. Results: Patients with ataxia teleangiectasia showed a reduction of the number of T-cells with a decrease in the T-helper cell subset (CD3: 990/µl, p〈0.0005 and CD4: 568/µl, p〈0.0005). The number of B-cells was low (CD19: 39/µl, p〈0.005). Moreover, there was an increase in highly activated T-lymphocytes which can be seen from a higher percentage of the HLA-DR- and CD45RO-expression in patients with ataxia teleangiectasia compared to the individuals of the control group (HLA-DR: 57%, p〈0.0005 and CD45RO: 82%, p〈0.001). At the same time, the expression of CD95 (Fas/AP01) was clearly increased (CD95: 74%, p〈0.001). Interpretation: The lymphocyte subset of the patients suffering from ataxia teleangiectasia shows a significant decrease of the B- and T-cell subsets. The reduced number of T-helper cells – caused by a CD45RA-cell loss – leads to a change in the relation „RA/RO”. It is possible that there is a link between the imbalance of „RA/RO”, the increase of highly activated T-lymphocytes and the higher expression of CD95 (Fas/APO1).
    Notes: Zusammenfassung Fragestellung: Können durch eine Charakterisierung der Lymphozytensubpopulationen bei Patienten mit Ataxia teleangiectatica Rückschlüsse auf den zellulären Defekt der Immunfunktionsstörung gezogen werden? Methodik: Mit Hilfe der Durchflußzytometrie und des Einsatzes monoklonaler Antikörper führten wir eine Immunophänotypisierung bei jeweils 10 Patienten mit Ataxia teleangiectatica und eines bezüglich des Alters und des Geschlechts gleichverteilten Kontrollkollektivs durch. Ergebnisse: Die Patienten mit Ataxia teleangiectatica zeigten verminderte T-Zell-Zahlen mit Abnahme der T-Helferzell-Subpopulationen (CD3: 990/µl, p〈0,0005 und CD4: 568/µl, p〈0,0005). Auch die B-Zell-Zahl war erniedrigt (CD19: 39/µl, p〈0,005). Die T-Lymphozyten befanden sich darüber hinaus vermehrt im aktivierten Zustand, erkennbar an einer prozentual erhöhten HLA-DR- und CD45RO-Expression (HLA-DR: 57%, p〈0,0005 und CD45RO: 82%, p〈0,001) sowie an einer Verschiebung der Relation „RA/RO” zugunsten der „RO”-Expression. Gleichzeitig war die Expression von CD95 (Fas/APO1) deutlich gesteigert (CD95: 74%, p〈0,001). Schlußfolgerung: Die Veränderungen der Lymphozytensubpopulationen zeigen bei den Patienten mit Ataxia teleangiectatica eine verminderte B- und T-Zell-Zahl. Die CD4-Lymphopenie – verursacht durch einen CD45RA-Zellverlust – bedingt eine Verschiebung der Relation „RA/RO”. Möglicherweise besteht ein Zusammenhang zwischen der Störung der Homöostase „RA/RO” und dem erhöhten Aktivierungsgrad der Zellen sowie der vermehrten CD95(Fas/APO1)-Expression.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Clinical and experimental nephrology 3 (1999), S. 254-260 
    ISSN: 1437-7799
    Keywords: Key words Low density lipoprotein ; Apoptosis ; Malondialdehyde ; TGFβ1 ; Unilateral ureteral obstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background. To test the hypothesis that oxidized low density lipoprotein (oLDL) is involved in the renal injury of obstructive nephropathy, male Sprague-Dawley rats weighing 125–150 g were used. Methods. Three days after arrival, the rats were randomly assigned to undergo: (1) sham operation, (2) left unilateral ureteral obstruction (UUO), or (3) reversal of the unilateral ureteral obstruction (R-UUO). Seven days after the reversal operation or 10 days after the sham or UUO procedure, all animals were killed by exsanguination under anesthesia, with blood taken from the abdominal aorta. LDL was prepared by gradient ultracentrifugation and used immedi-ately after isolation. Rat mesangial cells were utilized with an LDL concentration of 100 μg/ml/protein in the media. After 72 h, cell survival was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) method. Cell survival was determined by comparing the optical density between the control wells and the experimental wells. In order to investigate the mechanisms of injury and repair of obstructive nephropathy, data for kidney apoptosis, malondialdehyde (MDA), and transforming growth factor β1 (TGFβ1) mRNA were obtained in the sham-operated, UUO, and R-UUO groups. Results. Our results showed that LDL malondialdehyde during UUO was increased 87% over baseline values (P 〈 0.005). With R-UUO, the oxidized LDL dropped 23% from the peak values during UUO (P 〈 0.005), but was still different from that of the baseline values (P 〈 0.025). Rat mesangial cell survival, after 72 h exposure to oLDL, inversely correlated to oLDL cytotoxicity and showed a 14% drop during UUO compared with sham-operated animals (P 〈 0.01). Cell survival increased 11% after R-UUO (P 〈 0.02) and was not different from control values (P = NS). The apoptotic counts by the TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling) technique showed significant increases during UUO and a noticeable reduction after R-UUO. Conclusion. Our data support the proposition that UUO stimulates oxidation of LDL. The cytotoxicity of oLDL plays a significant role in the injury of UUO. A decrease in cytotoxicity was associated with the repair in R-UUO. Our observations that apoptosis follows this same pattern, point to the importance of apoptosis in the injury and repair of obstructive nephropathy. Future studies to interrupt these processes of injury may lead to novel treatment modalities in reversing the injury and hastening the repair of obstructive nephropathy.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric surgery international 15 (1999), S. 243-247 
    ISSN: 1437-9813
    Keywords: Key words Wilms' tumo ; Apoptosis ; Bcl-2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Wilms' tumor (WT) usually has a good outcome, although a poor prognosis is often related to more advanced stages and anaplastic features. Apoptosis occurs with variable frequency in malignant tumors, and may have a role in reducing their growth rate. The bcl-2 proto-oncogene inhibits apoptosis, and the consequent increase in the number of cells may play a role in the development of tumors. The aim of this study was to analyze the role of apoptosis and bcl-2 expression in WT. Twenty-six resected WT specimens were studied; 12 patients had stage I tumor, 4 stage II, 5 stage III, 3 stage IV, and 2 stage V. Twenty-three tumors were classified as favorable histology (FH) and 3 as unfavorable (UH). The mean follow-up was 34 months; 22 patients were alive and 4 were dead (2 with FH: 1 stage III and 1 stage IV, and 2 with UH stages 4). Apoptosis was detected by the in-situ end-labelling technique; bcl-2 expression was detected by immunohistochemistry. An apoptotic index (AI) was calculated as the ratio of apoptotic to normal cells in each specimen. The AI was lower in higher tumor stages, with a significant difference between stages I and IV (P 〈 0.05). In cases with UH, Al was lower than in tumors with FH (P 〈 0.01). The AI was also lower in patients who died than in those who survived (P 〈 0.01). In all specimens no correlation between AI and bcl-2 expression was observed. Progression to advanced stages of WT and a poor prognosis f anaplastic tumors may be linked with disruption of the mechanisms that control apoptosis. Bcl-2 does not play a role as a regulator of apoptosis in WT, other oncogenes and tumor-suppression genes may be more involved in inhibiting apoptosis in WT.
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  • 15
    ISSN: 1437-773X
    Keywords: Key words Epithelial rest of Malassez ; Cell ; cell interaction ; Extracellular matrix ; In vitro ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The present study investigated how cell plating density and extracellular matrix protein influence cell survival of epithelial rests of Malassez (ERM) in vitro. ERM cells were plated on culture dishes coated with laminin (LM), type IV collagen (type IV), or fibronectin (FN), or on noncoated dishes, (Non) at a cell density of 2 × 104–1 × 105/ml in a nonserum culture medium. XTT assays were performed to calculate the number of cells attached on the substrata after 6, 24, 48, and 72 h. Mean cell numbers were calculated, and significant differences were determined using ANOVA. When epithelial cells were cultured on various matrices at a cell density of less than 2 × 104/ml, the cells did not grow and then fell into apoptotic cell death, which was confirmed by transmission electron microscopy. The cell number was significantly increased in cells plated on FN compared to those on Non at a cell density of 4 × 104/ml–8 × 104/ml. These results suggest that both extracellular matrix proteins and cell–cell interactions may contribute to prevent apoptosis of ERM in vitro. Cell–cell interactions may be a more important factor than exogenous extracellular matrix proteins for the survival of ERM cells in vitro.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Journal of infection and chemotherapy 5 (1999), S. 139-143 
    ISSN: 1437-7780
    Keywords: Key words Fas ; ADR ; Bladder cancer ; Synergy ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fas and Fas ligand play an important role in cytotoxic T lymphocyte-mediated cytotoxicity. Like Fas ligand, anti-Fas monoclonal antibody (mAb) induces apoptosis of cells expressing Fas and mimics tumor necrosis factor-α (TNF-α) in its cytotoxic activity, but not in regard to other TNF-α-mediated activities. Since combination treatment with TNF-α and some anticancer chemotherapeutic agents results in synergistic cytotoxicity against various cancer cells, anti-Fas mAb may also synergize with anticancer agents in exerting cytotoxicity. The present study examined this hypothesis using bladder cancer cells. Cytotoxicity was examined by a 1-day microculture tetrazolium dye assay. Treatment of T24 cells with anti-Fas mAb in combination with mitomycin C, methotrexate, or 5-fluorouracil did not overcome their resistance to these agents. However, combination treatment with anti-Fas mAb and adriamycin (ADR) resulted in a synergistic cytotoxic effect on T24 cells, three other bladder cancer lines, and fresh bladder cancer cells derived from four patients. Treatment with ADR enhanced the expression of Fas on T24 cells. The expression of P-glycoprotein was not affected by the antibody-mediated sensitization. This study showed that combination treatment of bladder cancer cells with anti-Fas mAb and ADR can overcome their resistance and that the upregulation of Fas expression by ADR may play a role in the enhanced cytotoxicity.
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  • 17
    ISSN: 1437-773X
    Keywords: Key words Hepatocellular carcinoma ; Apoptosis ; Fas protein ; Bcl-2 protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Because the induction of apoptosis in cancer cells is very important in clinical management, it is useful to examine the association with the Fas–Fas ligand pathway and Bcl-2 protein family in apoptosis. We morphologically examined the expression of Fas and Bcl-2 proteins and induction of apoptosis by anti-Fas in four human hepatocellular carcinoma cell lines, PLC/PRF/5, Huh-6, and Huh-7, as well as OCUH-16, which was originally established in our university. Fas protein was expressed in 96% of OCUH-16 cells in cytoplasm, 24% of PLC/PRF/5 cells, 20% of Huh-6 cells, and no Huh-7 cells. Bcl-2 protein was expressed in 43%–72% of cells in cytoplasm and nuclei of the four lines examined. Administration of anti-Fas induced apoptosis in about 40% of OCUH-16 cells, but did not induce apoptosis in the other three cell lines. In conclusion, an original cell line, OCUH-16 cells, expressed Fas and Bcl-2 proteins and underwent apoptosis following treatment with anti-Fas, but the other three cell lines examined did not undergo apoptosis. OCUH-16 cells are thus very useful for the study of apoptosis and molecules related to apoptosis at the levels of cell-surface receptors and intracytoplasmic regulation of apoptosis.
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  • 18
    ISSN: 1437-7772
    Keywords: Key words Ovarian cancer ; Apoptosis ; IL-6 ; CDDP ; Taxol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background. Apoptosis is a cascade of events that is regulated by many factors. We studied the effects of interleukin-6 (IL-6) on chemotherapy-induced apoptosis in three human ovarian cancer cell lines (JV, GG, and NF). Methods. Cells were treated with the anticancer drugs cis-diamminedichloroplatinum (II) (CDDP) and paclitaxel (Taxol; Bristol-Myers Squibb Pharmacessticals, Noble Park, Australia) over a period of 72 h. The treatments were repeated in combination with human recombinant IL-6 or anti-IL-6 monoclonal antibody (anti-IL-6 mAb). The induction of cell death was examined by morphology and by internucleosomal DNA fragmentation. Results. Reduced cytotoxicity and fewer apoptotic cells were observed after treatment with CDDP or Taxol combined with IL-6 compared with treatment with CDDP or Taxol alone. However, treatment with CDDP or Taxol combined with anti-IL-6 mAb enhanced the cytotoxic effects of the drugs and increased the number of apoptotic cells. These findings indicated that apoptosis caused by CDDP or Taxol was influenced negatively by high doses of IL-6. Conclusion. The use of CDDP or Taxol combined with anti-IL-6 mAb may have therapeutic value for patients with ovarian cancer.
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  • 19
    ISSN: 1432-2307
    Keywords: Key words Anencephaly ; Thymic hyperplasia ; CD99 ; Apoptosis ; Aggregation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  In a significant proportion of cases, anencephaly is associated with thymic enlargement, suggesting a possibility that anencephalic fetuses have a functional disturbance in thymocyte differentiation and development. In this report, we demonstrated that CD99 expression was consistently reduced in cortical thymocytes of all anencephalic fetuses. In addition, the CD99-dependent aggregation of immature cortical thymocytes was almost completely impaired and apoptosis of thymocytes was markedly reduced in several cases. These results are in agreement with previous findings that CD99 regulates the aggregation and apoptosis of various types of cells. These data strongly suggest that functional disturbance of thymocytes and thymic hyperplasia are related to the reduced expression of CD99 molecule in anencephalic fetuses.
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  • 20
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    Mund-, Kiefer- und Gesichtschirurgie 3 (1999), S. 210-212 
    ISSN: 1434-3940
    Keywords: Schlüsselwörter Plattenepithelkarzinom ; Tumorneoangiogenese ; Apoptose ; Key words Squamous cell carcinoma ; Tumor neoangiogenesis ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Paclitaxel and docetaxel are potent drugs that are effective in the treatment of malignant tumors. The cytotoxic action of these drugs is not fully understood, but it appears to be mediated mainly through mitotic arrest and subsequent apoptosis. Because no information is available on the antiangiogenesis action of docetaxel, the investigations were performed to determine whether inhibition of neoangiogenesis plays a role in docetaxel’s antitumor efficacy. Four different mouse tumors, two squamous cell carcinomas (SCC-IV; SCC-VII) and two adenocarcinomas (MCA-4; MCA-29) were assayed for angiogenic activity using the in vivo i.c. angiogenesis assay. Tumor cells (5 × 105) were injected i.c. into the skin flap over the abdominal wall, and the number of new blood vessels at the tumor cell injection site was determined 2, 4, 6, 8, 10 and 12 days later. The mice were treated with docetaxel (Taxotere – 31.3 mg/kg i.v.) 1 or 4 days after tumor cell injection. The number of new blood vessels increased with time. Docetaxel reduced the number of newly formed blood vessels in MCAs, but not in SCCs. The reduction was associated with slower tumor growth. In a separate set of experiments we observed that docetaxel’s inhibitory effect on the two MCAs was histologically associated with massive tumor cell destruction by means of both apoptosis and necrosis. This was not observed for the two SCCs. Since no reduction in blood vessels occurred in tumors unresponsive to docetaxel, the inhibition of neoangiogenesis in docetaxel-responsive tumors was likely the result of a decrease in angiogenic stimuli due to docetaxel’s destruction of tumor cells.
    Notes: Die zytotoxische Aktivität der Taxane Paclitaxel und Docetaxel ist zum jetzigen Zeitpunkt noch nicht vollständig erklärt. Diese, zur Behandlung maligner Tumoren eingesetzten antineoplastischen Chemotherapeutika, scheinen jedoch weitgehend über die Blockierung der Mitose und die nachfolgende Induktion der Apoptose zu wirken. Über eine evtl. Hemmung der Neoangiogenese, wie sie kürzlich für Paclitaxel beschrieben wurde, liegen für Docetaxel noch keine Studienergebnisse vor. Es wurde deshalb untersucht, ob die therapeutische Aktivität von Docetaxel zur Hemmung der Neoangiogenese im Tumor beitragen kann. 4 murine Tumoren, 2 Plattenepithelkarzinome (SCC-VII; SCC-IV) und 2 Adenokarzinome (MCA-4; MCA-29), wurden in einem quantitativen intrakutanen In-vivo-Angiogenese-Assay experimentell untersucht. 5 · 10 5 Tumorzellen wurden in einen Abdominallappen der Maus injiziert. Die Anzahl neuformierter Blutgefäße und das Tumorwachstum wurden im 2tägigen Intervall über einen Zeitraum von zwischen 10 und 14 Tagen bestimmt. 2 Behandlungsgruppen wurde am 1. oder 4. Tag nach der Tumorzellinokulation Docetaxel (Taxotere – 31,3 mg/kg) i.v. injiziert. Die Plattenepithelkarzinome waren gegenüber der Therapie mit Docetaxel nicht sensibel, während die Adenokarzinome mit einer Abnahme der Gefäßzahl und einer Reduktion des Tumorvolumens reagierten. Histologisch zeigten die Adenokarzinome außerdem eine massive Tumorzelldestruktion durch Apoptose und Nekrose. Da die gegenüber Docetaxel nichtsensiblen Tumoren (Plattenepithelkarzinome) nicht mit einer Abnahme der Gefäßzahl reagierten, ist der beschriebene Effekt in den Adenokarzinomen am ehesten als indirekte Wirkung von Docetaxel zu werten. Die Tumorzelldestruktion führte in den betroffenen Tumoren zu einer verminderten Freisetzung endothelialer Mitogene wie VEGF und bFGF und zur Hemmung der Tumorneoangiogenese.
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  • 21
    ISSN: 1434-0879
    Keywords: Keywords Ischemia-reperfusion ; Heat shock ; HSP70 ; Kidney ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ischemia-reperfusion injury in the kidney is known to cause induction of the inducible form of the 70 kDa heat shock protein HSP70i (or HSP72). However, knowledge of the expressional regulation of the two coding genes for HSP70i –HSP70-1 gene and HSP70-2 gene – is very limited. We investigated the time course of HSP70-1 and -2 mRNA expression and its relation to cellular ATP levels in the renal cortex after different periods of unilateral warm renal ischemia (10–60 min) and reperfusion (up to 60 min) in 10-week-old male Wistar rats. Immediately after ischemia there was a significant induction of both HSP70i genes. While HSP70-1 expression constantly increased (up to 4-fold) during reperfusion, even to a higher extent with prolongation of ischemia, HSP70-2 mRNA – which was generally expressed at a far lower level than HSP70-1 mRNA – was strongly induced (3-fold) during reperfusion only after brief periods (10 min) of ischemia. Cellular ATP levels rapidly dropped to 5% with ischemia and the pattern of recovery during reperfusion significantly depended on the duration of the ischemic period, thus showing a good relation with the heat shock (protein) gene expression. We conclude that HSP70-2 is the more sensitive gene with a lower activation threshold by mild injury, while the HSP70-1 gene mediates the major response of heat shock protein induction after severe injury.
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  • 22
    ISSN: 1434-0879
    Keywords: Keywords Testicular neoplasms ; Embryonal cell ; carcinoma ; Apoptosis ; Lymphocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Disorders in the regulation of apoptotic cell death may contribute to cancer. Furthermore, lymphocytes are supposed to play a role in counteracting tumorigenesis by inducing apoptosis in different human tumors. In this study, for the first time, tumor cell and lymphocyte apoptosis were investigated systematically in human embryonal cell carcinoma. DNA fragmentation and DNA condensation were measured simultaneously on double-fluorescence-labeled testis tumor sections using immunofluorescence microscopy. Different apoptotic indices (AIs), based either on biochemical (DNA fragmentation) or morphological criteria (DNA condensation) alone or on a combination of both, were determined in different histological regions in and around the tumor. Using morphological criteria alone, 40–75% of all apoptotic cells were not detected. Based on previous observations this finding might be related to subsets of apoptotic cells which induce the process of DNA condensation without activation of processes responsible for DNA fragmentation. Moreover, the AIs of tumor cells and lymphocytes were highest in the tumor region, compared with regions around the tumor and distant from it; these findings are discussed in the context of the Fas/FasL system.
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  • 23
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    Plant molecular biology reporter 17 (1999), S. 371-383 
    ISSN: 1572-9818
    Keywords: epidermal peel ; extraction ; gene expression ; stomata ; tree tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stomatal guard cells are critical for maintenance of plant homeostasis and represent an interesting cell type for studies of leaf cell differentiation and patterning. Here we describe techniques for the isolation of guard cell RNA and protein from blended epidermal peels of Nicotiana glauca. The RNA isolation procedure is a modification of the hot borate method, which is particularly well-suited for recalcitrant tissues. Protein was extracted by disrupting guard cell-enriched epidermis with a French® press. This system offers the following advantages: relatively high yield, low or no contamination by other cell types, fresh tissue as a source of RNA and protein rather than protoplasts, and a plant species that is readily transformable. These techniques will allow for cloning and analysis of genes expressed in guard cells, application of traditional biochemical techniques to guard cell proteins, as well as characterization of genetic manipulation of guard cell function in transgenic plants.
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  • 24
    ISSN: 1432-0533
    Keywords: Key words c-Jun ; Jun B ; Jun D ; Apoptosis ; Colchicine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The expression of members of the Jun family of transcription factors was examined by immunohistochemistry, Western blotting, in situ hybridization and Northern blotting in the developing and adult rat brain following colchicine administration. Apoptotic cells, as revealed by their typical morphology and positive staining with the method of in situ end-labeling of nuclear DNA fragmentation, were restricted to granule cells of the dentate gyrus and olfactory bulb, and a few cells in the upper layers of the entorhinal cortex in adult rats, whereas widespread apoptosis occurred in developing rats after colchicine administration. No modifications in the expression of Jun D and Jun B, except for a generalized and moderate Jun B expression in glial cells, were observed in colchicine-treated rats. Generalized and strong c-jun mRNA induction and c-Jun/AP-1 (Ab-1) protein expression was observed in the cerebral neocortex, entorhinal and piriform cortices, CA1 and CA3 areas of the hippocampus and granule cell layer of the dentate gyrus in adult treated rats, thus indicating a generalized c-Jun response to colchicine administration. In contrast, c-Jun/AP-1 (N) and c-Jun/AP-1 (Ab-2) immunoreactivity was restricted to apoptotic cells in colchicine-treated adult and developing brains. Western blots of hippocampal homogenates and total brain homogenates in adult and developing rats, respectively, demonstrated a band of 39 kDa for the c-Jun/AP-1 (Ab-1) antibody in control animals, the intensity of which increased in colchicine-treated rats. However, a band of 37 kDa, the intensity of which also increased following colchicine administration, was observed for the c-Jun/AP-1 (N) and c-Jun/AP-1 (Ab-2) antibodies. Selective c-Jun/AP-1 (N) and c-Jun/AP-1 (Ab-2) expression was also observed in apoptotic cells of the SH-SY5Y neuroblastoma line after the addition of colchicine to the culture medium. Taken together, the present in vivo and in vitro results indicate a generalized c-Jun response to colchicine in sensitive cells, whereas the antibodies c-Jun/AP-1 (N) and c-Jun/AP-1 (Ab-2) recognize vulnerable cells dying via apoptosis.
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  • 25
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    Acta neuropathologica 97 (1999), S. 192-195 
    ISSN: 1432-0533
    Keywords: Key words Neuronal vacuolation ; Rottweiler dog ; Bcl-2 ; Bax ; c-Jun ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neuronal vacuolation, involving the cerebellar roof nuclei, Purkinje cells, selected nuclei of the brain stem, thalamus, Clarke’s column, anterior and posterior horns of the spinal cord, visceral autonomic ganglia and myenteric plexus, as well as axonal degeneration of the white matter of the brain stem, cerebellar pedunculi, dorsolateral columns of the spinal cord and ventral roots of the spinal cord, were observed in two young Rottweiler dogs which were clinically afflicted with hind limb weakness progressing to paraparesia, ataxia, intention tremor, and difficulty in swallowing and barking. The absence of modifications in Bcl-2 and Bax immunoreactivity, a lack of strong c-Jun/AP-1 (N) immunoreactivity in vacuolated cells, and the absence of DNA breaks, as seen with the method of in situ end-labeling of nuclear DNA fragmentation, all suggest that there is no involvement of the apoptotic pathway in vacuolated cells in this new neurodegenerative disorder.
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  • 26
    ISSN: 1432-0533
    Keywords: Key words Glucocorticosteroids ; Apoptosis ; Guillain-Barré syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Lipocortin-1 exerts a potent immunosuppressive effect on pathogenic T cells. In multiple sclerosis and experimental autoimmune encephalomyelitis levels of lipocortins are raised, suggesting their involvement in the recovery from an immunological insult or in neural regeneration. To further understand the role of lipocortins in the peripheral nervous system we have characterized lipocortin-1 levels and cellular distribution of lipocortin-1 immunoreactivity in sciatic nerves of rats with experimental autoimmune neuritis (EAN), a model of human Guillain-Barré syndrome. EAN was induced actively by immunization with bovine peripheral myelin (active EAN) or by adoptive-transfer (AT-EAN) of P2-specific T cells. Cellular infiltrates in serial and semithin cryosections were characterized by immunohistochemistry. In parallel, lipocortin-1 levels in tissue extracts were quantified by a sandwich-ELISA. Only weak lipocortin-1 immunoreactivity was found in nerves of control animals injected with non-pathogenic T cells. The majority of macrophages and lymphocytes in EAN lesions exhibited lipocortin-1 immunoreactivity. Some very heavily stained cells showed a distribution and morphology similar to ED-2-positive macrophages which were abundant during early stages of EAN. Lipocortin-1 expression in T cells and macrophages was proven by immunocytochemical studies in semithin serial sections. In tissue extracts, lipocortin-1 levels increased from 0.24 ± 0.14 μg/mg protein in controls receiving non-pathogenic T cells to a maximum of 0.55 ± 0.1 μg/mg protein in AT-EAN at the peak of disease, and then slowly decreased during clinical recovery but still remained elevated. In dose-response studies in AT-EAN, highest values of lipocortin-1 (0.71 ± 0.23 μg/mg protein) were recorded after transfer of 2 × 107 T cells. Increased levels of lipocortin-1 were also measured in active EAN but occurred during the recovery phase (0.65 ± 0.27 μg/mg protein). By analogy with other immune-mediated disorders, increased lipocortin-1 expression in the inflamed sciatic nerve in EAN may exert immunoregulatory functions in-situ and contribute to the termination of the autoimmune response.
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  • 27
    ISSN: 1432-0533
    Keywords: Key words Immediate early gene ; Heat shock protein ; Cerebral ischemia ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The neuroprotective role of the expression of heat shock protein (HSP) and immediate early gene remains unclear. Using immunoelectron microscopy, we examined the ultrastructural integrity of the neurons with expression of c-Fos, c-Jun and HSP70 in gerbils after transient cerebral ischemia and repefusion. Induction of c-Fos and c-Jun was observed in the CA3 region resistant to ischemia, while HSP70 was expressed not only in the CA3 but also in the vulnerable CA1 region. With immunoelectron microscopy, the expression of c-Fos/c-Jun and HSP70 was observed in the neurons which retained neuronal integrity except for mitochondrial swelling and polyribosomal disaggregation. In contrast, the CA1 neurons without immunoreaction for HSP70 showed cytoplasmic vacuoles and parallel stacking of rough endoplasmic reticulum, the features associated with the process of delayed neuronal death. These findings suggested that c-Fos and c-Jun were induced selectively in reversibly damaged neurons, whereas HSP70 was up-regulated even in neurons with irreversible damage, but was more preferentially and intensely expressed in neurons with reversible damage.
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  • 28
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    Acta neuropathologica 97 (1999), S. 5-12 
    ISSN: 1432-0533
    Keywords: Key words Creutzfeldt-Jakob disease ; Apoptosis ; Cell death ; Prion protein ; In situ end-labeling of nuclear DNA fragmentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The method of in situ end-labeling of nuclear DNA fragmentation was used in the study of ten patients (two biopsies, eight autopsies) with sporadic Creutzfeldt-Jakob disease (CJD). All the patients had the typical morphological lesions including neuron loss, spongiform change and astrocytosis. Four of them also showed prion protein (PrP) deposits in the cerebral cortex, and two of them kuru-like plaques in the cerebellum. A few cells with DNA breaks were found in the two biopsy cases; one of them, suffering from a panencephalopathic form of the disease, showed positive nuclei not only in the cerebral cortex but also in the subcortical white matter. Variable numbers of positive nuclei were observed in the gray and white matter in the eight autopsy cases, in which, although the distribution of positive cells roughly correlated with the distribution of neuron loss, no clear relationship was found as regards the distribution and degree of cell labeling and the degree of neuron loss. Furthermore, large numbers of positive cells were concentrated in a particular area, whereas a few cells were seen in a neighboring equally affected area. Positive glial cells in the plexiform layer of the CA1 area of the hippocampus, and in the frontal white matter were frequently encountered. Staining of the cytoplasm in a minority of cells was interpreted as the result of nuclear DNA leakage. None of the stained cells had the typical morphology of apoptosis; most particularly, peripheral chromatin condensation and formation of apoptotic bodies were not seen in any case. PrP deposits did not result in an increase of nuclear DNA breaks either within the area or in adjacent regions. Although positive cells were also observed in autopsy cases of controls which were processed in the same way, positive labeling as a whole was higher in CJD than in age-matched controls. These results show that brain nuclear DNA is vulnerable in CJD, and suggest that increased DNA vulnerability has a role in cell death and neuron loss. Since nuclear shrinkage and positive nuclear staining with the method of in situ end-labeling of nuclear DNA fragmentation are not exclusive to apoptosis, further information is needed to categorize cell death in CJD as apoptosis. Necrosis or other forms of cell death, as well as increased DNA vulnerability to agonal changes of the individuals, and to postmortem delay in the fixation of the tissues, may account for additional positive staining in cases examined at autopsy.
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  • 29
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    Anatomy and embryology 200 (1999), S. 203-214 
    ISSN: 1432-0568
    Keywords: Key words Extracellular material ; Cell proliferation ; Apoptosis ; Anoikis ; Tenascin ; Laminin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Extracellular material molecules play a key role in the regulation of morphogenesis and differentiation of a large number of organs including the central nervous system. However, the role of the neural basement membrane in the growth of different parts of the neural tube has yet to been delineated. Here, the structural and compositional modifications of the basement membrane (BM) of rhombencephalic tectoria lamina anlage (RTLA) have been examined during the process of RTLA epithelial attenuation. Between stages 10 to 11– the presumptive RTLA epithelium showed a structure, thickness and cell-proliferating capacity similar to those observed in other zones of the rhombencephalic walls. Moreover, the rhombencephalic vesicles were surrounded by a continuous BM that was heterogeneous both ultrastructurally and with regard to ruthenium red, laminin and tenascin distribution. After stage 11, the RTLA epithelium underwent a rapid process of attenuation and change to a stratified flattened epithelium. During this remodelling process, apoptosis and inhibition of both PCNA expression and 3H-thymidine uptake occurred in the RTLA epithelium. The BM of the RTLA underwent a process of degration at the beginning of the remodelling, and apoptosis and cell proliferation inhibition of RTLA epithelium were also observed. The loss of the biochemical signals encoded within the BM could lead to cell shape changes, cell proliferation inhibition and to the anoikis type of cell death. Our findings support the idea that the BM surrounding the neural tube plays a key role in controlling both the structure and growth of the CNS during the early developmental stages.
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  • 30
    ISSN: 1432-0568
    Keywords: Key words Somite explant culture ; Sonic hedgehog protein ; Myogenic induction ; Primary fiber type diversity ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Primary skeletal muscle fibers first form in the segmented portions of paraxial mesoderm called somites. Although the neural tube and notochord are recognized as crucial in patterning myogenic cell lineages during avian and mammalian somitic myogenesis, the source, identities, and actions of the signals governing this process remain controversial. It has been shown that signals emanating from the ventral neural tube and/or notochord alone or Shh alone serve to activate MyoD expression in somites. However, beyond a role in initiating MyoD expression, little is known about the effects of Shh on primary muscle fiber formation in somites of higher vertebrates. The studies reported here investigate how the ventral neural tube promotes myogenesis and compare the effects of the ventral neural tube with those of purified Shh protein on fiber formation in somites. We show that purified Shh protein mimics actions of the ventral neural tube on somites including initiation of muscle fiber formation, enhancement of numbers of primary muscle fibers, and particularly, the formation of primary fibers that express slow myosin. There is a marked increase in slow myosin expression in fibers in response to Shh as somites mature. The effects of ventral neural tube on fiber formation can be blocked by disrupting the Shh signaling pathway by increasing the activity of somitic cyclic AMP-dependent protein kinase A. Furthermore, it was demonstrated that apoptosis is a dominant fate of somite cells, but not somitic muscle fibers, when cultured in the absence of the neural tube, and that application of Shh protein to somites reduced apoptosis. The block to apoptosis by Shh is a manifestation of the maturity of the somite with a progressive increase in the block as somites are displaced rostrally from somite III forward. We conclude that purified Shh protein in mimicking the effects of the ventral neural tube on segmented mesoderm can exert pleiotropic effects during primary myogenesis, including: control of the proliferative expansion of myogenic progenitor cells, antagonism of cell death pathways within the precursors to muscle fibers, and during the crucial process of primary myogenesis, can exert an effect on diversification of muscle fiber types.
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  • 31
    ISSN: 1432-0533
    Keywords: Key words Parkinson’s disease ; Apoptosis ; Bcl-2 ; Bax ; Bcl-x
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We studied the substantia nigra of three Parkinson’s disease (PD) patients and three age-matched individuals by in situ DNA-end labeling (ISEL) and immunohistochemistry for the apoptosis regulating proteins Bcl-2, Bax and Bcl-x on 50 consecutive sections per patient. No melanin-containing cell was identified with typical apoptotic changes in either patient or control substantia nigra. With prolonged reaction-time the terminal transferase-mediated DNA-end labeling revealed a signal in 2.0 ± 1.2% melanin-containing cells in PD compared to 1.3 ± 1.1% in control. This difference did nor reach statistical significance and no condensation or margination of the chromatin was evident. No significant changes of any of the apoptosis regulating proteins were apparent in PD substantia nigra. These findings do not support the hypothesis that apoptosis plays a central role in the pathogenesis of PD.
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  • 32
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    Acta neuropathologica 97 (1999), S. 279-287 
    ISSN: 1432-0533
    Keywords: Key words Canine distemper virus ; Oligodendrocytes ; Apoptosis ; Necrosis ; Demyelination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Canine distemper virus (CDV) causes a multifocal demyelinating disease in dogs. It was previously shown that the initial demyelinating lesions are directly virus induced since a correlation between the occurrence of demyelination and CDV replication in white matter cells was observed. During the course of infection oligodendrocytes undergo distinct morphological alterations, partly due to a restricted CDV infection of these cells, and eventually disappear from the lesions. This phenomenon has been described in vivo as well as in vitro. However, the reason for the morphological alterations and the following oligodendroglial depletion remained unclear. Since virus infection can induce cell death, it was investigated whether apoptosis or necrosis plays a role in the pathogenesis of demyelination in canine distemper. In brain tissue sections from dogs with acute distemper apoptotic cells were not detected within the demyelinating lesions using morphological and biochemical cell death criteria. In chronic distemper, apoptotic cells – presumably inflammatory cells – were seen within the perivascular cuffs. These in vivo findings were correlated to the in vitro situation using CDV-infected primary dog brain cell cultures as well as Vero cells. Infection with culture-adapted CDV lead to massive necrosis but not to apoptosis. After infection with virulent CDV neither apoptosis nor necrosis was a predominant feature in either culture system. These findings suggest that virus-induced demyelination in canine distemper is not the direct consequence of apoptosis or necrosis. It is speculated that another mechanism must be responsible for the observed morphological alterations of oligodendrocytes, ultimately leading to demyelination.
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  • 33
    ISSN: 1432-0568
    Keywords: Key words Brain ; Cortical parcellation ; Development ; Proteoglycans ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Nitric oxide (NO) regulates several functions both in the developing and the adult central nervous systems (CNS). During development, NO is assumed to contribute to the histogenetic differentiation of the CNS especially through the modulation of programmed neuronal death. The embryonal and postnatal changes in the distribution of the cortical NO producing system were studied in Balb/c mice using immunocytochemistry for nitric oxide synthase-I (NOS-I) and NADPH-diaphorase (NADPH-d) enzyme histochemistry. NOS-I reactive neurons (RN) appeared first at embryonic day 14 (E14) in the spinal cord in the vicinity of the central canal, and later, at E16–18, in the thalamus and striatum. The first cortical region to present NOS-I reactivity was the parietal cortex, which happened at E18–20. After E20 the number of NOS-I RN increased in every cortical area, plateauing at postnatal day 4 (P4). In parietal regions, however, the highest density of NOS-I RN was observed already at P1. The neuronal packing density (PD) of NOS-I RN declined until adulthood, interrupted by a transient increase in some cortical areas at the onset of puberty. The heterochronous appearance of NOS-I during pre- and postnatal development of different brain regions and the sequence of up- and downregulation of expression until adult stages points to an important role of NO in brain development and functional differentiation.
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  • 34
    ISSN: 1432-0568
    Keywords: Key words Synaptogenesis ; Primate ; Spinal cord ; Apoptosis ; Neuropeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Development of glomerular synapses in the superficial dorsal horn has been studied in the embryonic macaque spinal cord using light and electron microscopic techniques including Golgi impregnation, 3H-thymidine radioautography and pre-embedding immunohistochemistry of substance P (SP), calcitonin gene related peptide (CGRP), calbindin D-28 K (CB) and parvalbumin (PV). The study revealed that substantia gelatinosa cells of the primate dorsal horn are generated last, but unlike in rodents, synaptogenesis in this region starts at early embryonic (E) stages of the 165-day long gestation. Already by E30, both Type 1 (light) and 2 (dark) dorsal root axons and their growth cones are identifiable within the oval bundle of His, before they form synaptic contact with their final target cells. Subsequently they invade the dorsal horn and enter the bisecting interfaces formed by orderly programmed cell death. Each type of scalloped (sinusoid) central primary afferent terminal (i.e. DSA, RSV and LDCV) have well defined pre- and post-synaptic specializations already by E40. Among the neuropeptides studied, SP appears first at E67 and CGRP at E70 in the lateral position but within a few days both of them are spread to the entire superficial dorsal horn. Both SP and CGRP are present in the thin dorsal root axons and their growth cones, giving rise to scalloped and simple axon terminals. PV is transiently present in the entire length of the thick dorsal root afferents before becoming concentrated in the synaptic boutons. CB is displayed mainly in neurons of the lamina I and III. Dendrites of CB-immunoreactive cells establish synaptic connection with each type of dorsal root afferents, including glomerular synaptic complexes. These data reveal that the superficial dorsal horn in the primate spinal cord develops its characteristic synaptic complexes much earlier in gestation than in any other mammalian species studied. Furthermore, characteristic cytological features of the prospective glomerular complex emerge before establishment of the final synaptic contacts.
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  • 35
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    Archives of dermatological research 291 (1999), S. 212-216 
    ISSN: 1432-069X
    Keywords: Key words UV irradiation ; Solar-simulated irradiation ; Apoptosis ; bcl-2 ; bax
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recently, the proto-oncogenes bcl-2 and bax have emerged as important regulators of the apoptotic form of cell death. We examined UV irradiation-elicited apoptosis and regulation of bcl-2 and bax expression both in vivo in human skin and in vitro in HeLa cells. Using flow cytometric analysis, HeLa cells were found to undergo apoptosis at the 12-h time-point after exposure to UVB irradiation (100 mJ/cm2). The expression of bcl-2 mRNA was found to decrease after a single dose of UVB radiation (doses 10–200 mJ/ cm2). In contrast, the expression of bax mRNA was not significantly changed. When human skin was irradiated with a single dose of solar-simulated radiation (40 mJ/cm2), Bcl-2-positive cells were significantly reduced in the epidermis at the 3- and 6-h time-points. Our results suggest that UV irradiation downregulates bcl-2 expression both in vitro at the mRNA level and in vivo at the protein level, and that downregulation of bcl-2 constitutes a mechanism of potential importance in UV-induced apoptosis in human epidermis.
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  • 36
    ISSN: 1432-069X
    Keywords: Key words TUNEL ; Apoptosis ; Trichilemmal ; keratinization ; Epidermal appendages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 37
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    Archives of dermatological research 291 (1999), S. 303-305 
    ISSN: 1432-069X
    Keywords: Key words Langerhans cells ; Sunburn cells ; UV ; erythema ; Apoptosis ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 38
    ISSN: 1432-069X
    Keywords: Key words Keratinocyte ; UVB ; Apoptosis ; Calcium ; p53
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Normal human keratinocytes are stimulated to proliferate in serum-free medium containing subphysiological concentrations of calcium (0.09 mM, low calcium). In this study, we examined the effect of increased levels of extracellular calcium (2.0 mM, normal calcium) on UVB-induced apoptosis. Apoptosis was assessed by changes in cellular morphology, annexind V-FITC flow cytometry, and the formation of internucleosomal DNA ladders. High doses of UVB induced keratinocytes grown in low calcium medium to undergo apoptosis. In contrast, keratinocytes grown for 72 h in normal calcium medium were completely resistant to UVB-induced apoptosis. No apoptosis was observed even at UVB doses as high as 1200 J/m2. However, despite the lack of UVB-induced cell death, keratinocytes grown in normal calcium medium lost the ability to proliferate following high levels of UVB irradiation. High doses of UVB also increased the expression of the differentiation-specific proteins involucrin and cytokeratin 10 in a dose-dependent manner. In addition, growth in normal calcium medium lowered the UVB-induced stimulation of the p53 protein and altered the normal subcellular localization pattern of p53. UVB irradiation of human keratinocytes grown in normal calcium medium may be inducing further cell differentiation in the absence of overt cell death.
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  • 39
    ISSN: 1432-0584
    Keywords: Key words IL-6 variants ; Cell cycle ; Apoptosis ; Multiple myeloma ; Cell line
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Interleukin-6 (IL-6) serum levels and the proliferative activity of bone marrow plasma cells have been described as important prognostic factors for survival duration in multiple myeloma (MM) patients. Since growth of neoplastic plasma cells is frequently promoted by IL-6, inhibition of its activity has been considered for the management of MM patients. With a similar rationale, IL-6 variants characterized by wild-type or increased affinity for the ligand-specific IL-6 α receptor chain and reduced ability to bind and/or dimerize the gp 130 chain have recently been generated. In the present study, the antiproliferative effects of the variants Sant1, Sant5, and Sant7, characterized by increasing antagonistic activity, were investigated by means of a detailed cell kinetic and apoptotic analysis of the IL-6-dependent MM XG-1 cell line. A significant reduction in the mean percent of XG-1 cells in active S-phase (DNA/bromodeoxyuridine incorporation) from 41% to 28.1% (p=0.04), 25.8% (p=0.04), and 15.3% (p=0.02), respectively, was observed using Sant1, Sant5, and Sant7. These effects were confirmed using the acridine-orange (AO) flow-cytometric technique, which showed a similar reduction of S-phase (34.2% of baseline value) in the presence of Sant1, Sant5, and Sant7, as well as a significant G1b arrest (from 44.5% to 47.6%, 48%, and 64.9%). Furthermore, IL-6 variants were capable of down-regulating the G1 cell cycle regulatory protein cyclin D1 expression. Cell cycle effects were coupled with a significant increase of apoptosis, measured by the AO and the terminal deoxynucleotidyl transferase assays, from 12.9% (control culture with IL-6) to 21.2% (Sant1), 29.1% (Sant5), and 23.5% (Sant7). These results were comparable to those obtained by depriving XG-1 of recombinant IL-6. Our study documents the antiproliferative activity exerted by IL-6 mutants on the XG-1 cell line, thus supporting the investigation of these molecules on primary MM cells.
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  • 40
    ISSN: 1432-0584
    Keywords: Key words Idiopathic myelofibrosis ; PCNA labeling ; Apoptosis ; Dynamic disease features ; Prognosis ; Proportion of life loss ; Bone marrow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A retrospective study of 120 patients with the clinically and histologically established diagnosis of idiopathic (primary) myelofibrosis (IMF) was performed to determine prognostic factors of predictive value, including parameters characterizing the dynamics of hematopoietic cell kinetics. In contrast to previous studies, our cohort comprised the full spectrum of the disease, from initial prefibrotic to advanced osteosclerotic stages. The in situ end-labeling (ISEL) technique was used to demonstrate apoptosis, in order to determine dynamic parameters of predictive value. Cell proliferation was evaluated by employing the monoclonal antibody PC10 directed against proliferating cell nuclear antigen (PCNA). Proliferative activity (PCNA index) and frequency of apoptosis showed significant differences between early and advanced fibrosclerotic stages of disease. Decrease in proliferation indicated a significantly shorter survival, whereas a higher frequency of apoptotic cells was associated with a better prognosis. It may be speculated that a normal or enhanced proliferation rate expressed by PCNA positivity (late G1- and S-phase of the cell cycle) that is accompanied by a higher incidence of apoptosis reflects the regenerative (turnover) capacity of hematopoiesis. This may apply especially to early hypercellular stages without relevant myelofibrosis. In consideration of a recently published multivariate risk model, a simplified synthesis score for stratification of a patient's prognosis was constructed. Age, degree of anemia, leukocytes, and platelet count were regarded as the most important parameters. A substantial improvement of prognostic efficiency was further achieved by including PCNA index and frequency of apoptosis. Our results are in keeping with the assumption that generalization, indicated by myeloid metaplasia, has a prodigious impact on prognosis in IMF. Furthermore, in this context dynamic features such as proliferative activity and frequency of apoptosis exert an additional predictive value.
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  • 41
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    Diabetologia 42 (1999), S. 1033-1049 
    ISSN: 1432-0428
    Keywords: Keywords Adipogenesis ; adipose tissue ; cofactors ; gene expression ; fatty acids ; insulin resistance ; nuclear receptors ; prostaglandin ; thiazolidinediones ; Type II diabetes ; transcription.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The peroxisome proliferator-activated receptor gamma (PPARγ) quickly evolved over the last decade from a new orphan receptor to one of the best characterized nuclear receptors. This fast pace in PPARγ research was triggered by two main discoveries. Firstly, that PPARγ was shown to have a key role in adipogenesis and be a master controller of the “thrifty gene response” leading to efficient energy storage. Secondly, the discovery that its synthetic ligands, the thiazolidinediones, are promising insulin sensitizing drugs, which are currently being developed for the treatment of Type II (non-insulin-dependent) diabetes mellitus. More recently this nuclear receptor emerged from a role limited to metabolism (diabetes and obesity) to a power player in general transcriptional control of numerous cellular processes, with implications in cell cycle control, carcinogenesis, inflammation, atherosclerosis and immunomodulation. This widened role of PPARγ will certainly initiate a new flurry of research, which will not only refine our current often partial knowledge of PPARγ but more importantly also establish that this receptor has a definite role as a primary link adapting cellular, tissue and whole body homeostasis to energy stores. [Diabetologia (1999) 42: 1033–1049]
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  • 42
    ISSN: 1423-0127
    Keywords: TNFα ; Fas ; FasL ; Apoptosis ; Cytokine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The CD3+/TCRαβ+ T-cell-mediated hepatic inflammation induced byPropionibacterium acnes could be divided into an acute and a chronic phase. The acute phase occurred within 72 h after injection and displayed hepatic apoptosis. Anti-TNFα antibody inhibited both theP. acnes-induced hepatic apoptosis and lymphocyte infiltration seen in this phase, indicating the involvement of this cytokine. Thereafter, a chronic phase was manifested from days 7 to 14 after injection. It was characterized as granulomatous inflammation admixed with apoptosis of infiltrating lymphocytes and some hepatocytes. Immunohistochemical staining showed that the infiltrating lymphocytes displayed TNFα, TNF type I receptor and a variety of cytokines including IL-1β, IL-4, IL-6, IL-10, IFNγ or IL-12. Interestingly, in naive mice, the arteries in the liver constitutively expressed IFNγ. Its expression appeared to be substantially increased at 48 h, decreased at 72 h, and increased again on day 14 afterP. acnes injection. Furthermore, Fas or FasL was only detected on the lymphocytes within the granuloma. We conclude thatP. acnes can induce a TNFα-mediated acute hepatic apoptosis which subsequently progress to a T-cell-mediated granulomatous hepatitis with increased expression of multiple cytokines and Fas/FasL.
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  • 43
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    Journal of biomedical science 6 (1999), S. 433-438 
    ISSN: 1423-0127
    Keywords: AIDS dementia complex ; Antioxidants ; Apoptosis ; Cerebral atrophy ; gp120 ; HIV-1 protease ; Human neuroblastoma cell ; Neuroprotection ; Protease inhibitor (KNI-272)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A significant number of adult male patients with acquired immunodeficiency syndrome develop cerebral atrophy and progressive brain disorders such as dementia complex and neuropsychiatric problems. Upon entering the brain via activated macrophages or microglias, the human immunodeficiency type 1 virus (HIV-1) may produce cytotoxic factors such as HIV-1 envelope protein (gp 120) and protease. Owing to significant proteolysis of nonviral proteins, the protease derived from HIV-1 may be detrimental to brain cells and neurons. Our results revealed that HIV-1 protease, at nanomolar concentrations, was as potent as gp 120 in causing neurotoxicity in human neuroblastoma neurotypic SH-SY5Y cells. As shown by the Oncor ApopTag staining procedure, HIV-1 protease significantly increased the number of apoptotic cells over the serum-free controls. Moreover, HIV-1 protease-induced neurotoxicity was blocked by a selective protease inhibitor, kynostatin (KNI-272). Antioxidants such as 17β-estradiol, melatonin, andS-nitrosoglutathione also prevented protease-induced neurotoxicity. These findings indicate that oxidative proteolysis may mediate HIV-1 protease-induced apoptosis and the degeneration of neurons and other brain cells. Centrally active protease inhibitors and antioxidants may play an important role in preventing cerebral atrophy and associated dementia complex caused by HIV-1.
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  • 44
    ISSN: 1432-0428
    Keywords: Keywords Obesity ; genetics ; uncoupling protein-3 ; gene expression ; skeletal muscle.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims: Uncoupling protein-3 is a member of a protein family that serves to dissipate energy in the form of heat thereby modulating energy expenditure. Alternative processing of uncoupling protein-3 transcripts results in two mRNA species that encode a large and small protein, perhaps differing in functional activity. Since obesity is associated with disrupted energy homeostasis, we measured muscle mRNA expression in morbidly obese and lean subjects. Methods: The two uncoupling protein-3 mRNA species were quantified in muscle tissue using an RNase protection assay. Gene locus effects on mRNA expression were studied by quantitative allele-specific primer extension. Results: In both obese and lean subjects, the mRNA species encoding the small protein isoform was twice as abundant as the mRNA species encoding the large protein isoform. Neither the total uncoupling protein-3 mRNA expression nor the molar abundance ratios of the two mRNA species differed between obese and lean male or female subjects. Women who had lost 37 ± 22 kg of weight in response to dietary restriction and continued a hypocaloric diet displayed lower mRNA than obese (p 〈 0.005) or lean women (p 〈 0.05). Primer extension assays in lean and obese subjects showed similar allelic mRNA abundance in all but one subject studied. Conclusion: Muscle expression of the two uncoupling protein-3 mRNA species is similar in obese and lean people. In obese patients, prolonged hypocaloric diet downregulates uncoupling protein-3 mRNA expression in muscle and can thereby enhance its energy efficiency. Sequence substitutions at the gene locus may only be minor determinants of mRNA expression in muscle tissue. [Diabetologia (1999) 42: 302–309]
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  • 45
    ISSN: 1432-0428
    Keywords: Keywords Uncoupling proteins ; exercise ; tetraplegia ; skeletal muscle ; mRNA ; gene expression ; polymerase chain reaction.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. The regulation of uncoupling protein 2 and uncoupling protein 3 gene expression in skeletal muscle has recently been the focus of intense interest. Our aim was to determine expression of uncoupling protein 2 and 3 in skeletal muscle from tetraplegic subjects, a condition representing profound muscle inactivity. Thereafter we determined whether exercise training would modify expression of these genes in skeletal muscle. Methods. mRNA expression of uncoupling protein 2 and 3 was determined using quantitative reverse transcription-polymerase chain-reaction. Results. Expression of uncoupling protein 2 and 3 mRNA was increased in skeletal muscle from tetraplegic compared with able-bodied subjects (3.7-fold p 〈 0.01 and 4.1-fold, p 〈 0.05, respectively). A subgroup of four tetraplegic subjects underwent an 8-week exercise programme consisting of electrically-stimulated leg cycling (ESLC, 7 ESLC sessions/week). This training protocol leads to increases in whole body insulin-stimulated glucose uptake and expression of genes involved in glucose metabolism in skeletal muscle from tetraplegic subjects. After ESLC training, uncoupling protein 2 expression was reduced by 62 % and was similar to that in able-bodied people. Similarly, ESLC training was associated with a reduction of uncoupling protein 3 expression in skeletal muscle from three of four tetraplegic subjects, however, post-exercise levels remained increased compared with able-bodied subjects. Conclusion/interpretation. Tetraplegia is associated with increased mRNA expression of uncoupling protein 2 and 3 in skeletal muscle. Exercise training leads to normalisation of uncoupling protein 2 expression in tetraplegic subjects. Muscle disuse and physical activity appear to be powerful regulators of uncoupling protein 2 and 3 expression in human skeletal muscle. [Diabetologia (1999) 42: 826–830]
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  • 46
    ISSN: 1279-8509
    Keywords: p53 ; Apoptosis ; PKC ; g-irradiation ; Transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Several mutations prevent the expression of p53 in the human lymphoblastoid T cell line Jurkat. Restoration of p53 in Jurkat cells had no effect on the cell growth but markedly increased the amount of apoptosis induced by g-irradiation. Inhibition of RNA synthesis using 5,6-dichlorobenimidizole riboside had little effect on apoptosis induced by irradiation in the presence of p53 and did not affect the p53-independent apoptotic pathway. Expression of p53 also had no effect on the expression levels of proteins such as Fas, GADD45, Bax, Bcl-2, Bcl-xL or p53 induced proteins (PIGS) in resting cells or after irradiation. Activation of protein kinase C by phorbol 12-myristate 13-acetate produced an almost complete inhibition of p53-independent apoptosis following irradiation, whereas no significant effect was observed on the rate of p53-induced apoptosis. Although phorbol 12-myristate 13-acetate strongly induced p21 and stabilised p53 in the resting transfected Jurkat cells, neither apoptosis nor cell arrest was observed. In summary, this work shows that p53 enhances the radiosensitivity of Jurkat cells through an apoptotic process that is triggered by irradiation and is largely independent of RNA synthesis and protein kinase C activation. Apoptosis in p53- negative Jurkat cells is strongly inhibited by PMA indicating that the pathway triggered by p53 may be distinct from apoptotic pathways used in its absence.
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  • 47
    ISSN: 1423-0127
    Keywords: Autoimmunity ; Apoptosis ; IL-2 ; FasL ; Tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Studies of several gene knockout mice suggest an interesting association of a moderate T cell response with systemic autoimmune diseases. In addition, CD95 ligand (FasL) expression in some strains of these mice is impaired. Because FasL is critically involved in regulating peripheral tolerance, there may be a link between autoimmune diseases and a moderate T cell response that cannot activate the FasL gene. Here, we propose that there are two thresholds of T cell activation. When moderately stimulated, T cells can be activated to the low (1st) threshold, which permits the induction of CD40L, IL-2, IL-4, and other components that help the immune response. The high (2nd) activation threshold can only be achieved by a strong and concurrent stimulation through TCR and IL-2R. Once the high threshold is reached, FasL is produced to induce apoptosis of the activated T and B cells. In the absence of the FasL-mediated downregulation, the activated B cells become efficient antigen-presenting cells for self-antigens and excellent responders for T cell help. Such an exacerbating condition, induced by recurrent and moderate activation, favors the development of autoreactive T cells and autoantibody production. Evidence supporting this hypothesis and some predictions that can be tested are described.
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  • 48
    ISSN: 1423-0127
    Keywords: Glioma ; Apoptosis ; Vandate ; Akt ; PKB
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The dual signal hypothesis of apoptosis holds that a common signal can activate both apoptotic and proliferative pathways. The fate of a cell is dependent on which of these two pathways predominates. In the MAPK family of kinases, ERK and JNK have been proposed to mediate apoptosis whereas the PI3K-stimulated kinase, Akt/PKB, has been shown to inhibit apoptosis. The object of this study was to determine the role of these kinases in a glioma model of apoptosis. We have previously shown that K252a induces apoptosis and inhibits kinase activity. In this study we confirm these results and shown that the protein tyrosine phosphatase inhibitor sodium vanadate activates ERK, JNK and Akt/PKB, but does not stimulate proliferation. Vanadate did protect T98G cells from K252a-induced apoptosis, an effect that was abolished by addition of the PI3K inhibitor wortmannin. This suggests that PI3K and Akt/PKB may be responsible for mediating vanadate's protective effect on glioma cells. We conclude that the intracellular balance between protein phosphorylation pathways is a critical determinant of both cell proliferation and cell death.
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  • 49
    ISSN: 1432-0843
    Keywords: Key words Cyclin-dependent kinase ; Cytotoxicity ; Apoptosis ; Multidrug resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: To determine the in vitro effects of flavopiridol on bladder cancer cell lines, immortalized urothelial cell lines, and normal urothelial cells well characterized for defects in p53, pRb, and p16. Methods: Growth inhibition was assessed via an MTT assay and apoptosis via DAPI nuclear staining. Cell cycle analysis was performed via propidium iodide staining and fluorescent activated cell sorting (FACS). Multidrug-resistant cells were generated by continuous exposure to doxorubicin. Results: Growth inhibition was not correlated with inactivation of p53, pRb, or p16. All cells experienced G2/M arrest within 24 h of flavopiridol exposure. Modest apoptosis was observed but required 72 h of continuous drug exposure to become evident. There was no obvious synergistic or antagonistic toxicity when flavopiridol was combined with radiotherapy or cisplatin dosed at the IC50 despite the observation that radiotherapy and flavopiridol led to more profound G2/M arrest than either agent alone. Doxorubicin-resistant cells, demonstrated to overexpress the MDR1 multidrug-resistance protein were equally as sensitive to flavopiridol as the parental cells. Conclusions: Flavopiridol is a novel cell cycle inhibitor that may be a useful agent in bladder cancers with tumor suppressor gene alterations and/or multidrug resistance.
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  • 50
    ISSN: 1432-0843
    Keywords: Key words Dolastatin ; Lung cancer ; Apoptosis ; Xenografts ; Experimental therapeutics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: Dolastatin 10 is a natural cytotoxic peptide which acts through the inhibition of microtubule assembly. Studies have suggested that such agents can induce apoptosis in association with bcl-2 phosphorylation. Since bcl-2 overexpression is common in small-cell lung cancer (SCLC), we evaluated the activity of dolastatin 10 in SCLC cell lines and xenografts. Methods: In vitro growth inhibition was evaluated with a standardized MTT assay and apoptosis with fluorescent microscopy and a TUNEL assay. Immunoblot analysis and phosphatase digestion were used to determine bcl-2 modification. In vivo activity was evaluated in subcutaneous and metastatic SCLC xenograft models in SCID mice. Results: Dolastatin 10 had growth inhibitory activity against four SCLC cell lines (NCI-H69, -H82, -H446, -H510) with IC50 values ranging from 0.032 to 0.184 nM. All four cell lines exhibited evidence of apoptosis after 48 h of exposure to 1.3 nM dolastatin 10. Immunoblot analysis revealed that 1.3 nM dolastatin 10 altered the electrophoretic mobility of bcl-2 in NCI-H69 and -H510 cells within 16 h of treatment. Incubation of protein extract from dolastatin 10-treated NCI-H69 and -H510 cells with calcineurin resulted in the disappearance of the altered mobility species, suggesting dolastatin 10-induced bcl-2 phosphorylation. In in vivo studies, 450 μg/kg of dolastatin 10 IV × 2 given after intravenous injection of NCI-H446 cells completely inhibited tumor formation. In established subcutaneous NCI-H446 xenografts, 450 μg/kg of dolastatin 10 IV induced apoptosis in the majority of tumor cells within 96 h, resulting in a log10 cell kill of 5.2 and an increase in median survival from 42 to 91 days. Conclusions: These findings suggest that dolastatin 10 has potent activity against SCLC and that the modulation of apoptotic pathways deserves further evaluation as an anticancer strategy.
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  • 51
    ISSN: 1432-0843
    Keywords: Key words Baccatin III ; Paclitaxel ; Apoptosis ; Mitotic arrest ; bcl-2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: Paclitaxel has been demonstrated to possess significant cell-killing activity in a variety of tumor cells by induction of apoptosis, but the mechanism by which paclitaxel leads to cell death and its relationship with mitotic arrest is not entirely clear. In this study, baccatin III, a synthetic precursor of paclitaxel, was used to analyze whether paclitaxel-induced apoptosis can be a separate event from microtubule bundling and G2/M arrest. Methods: Several different methods including DNA fragmentation, flow cytometric analyses, TdT-mediated dUTP nick end labeling (TUNEL) and time-lapse video microscopy were used to analyze apoptotic cell death induced by baccatin III and its possible correlation with cell cycle distribution. Results: Our results demonstrated that baccatin III could also cause apoptotic cell death in both BCap37 (a human breast cancer cell line) and KB cells (derived from human epidermoid carcinoma), but had less effect on microtubule bundling and G2/M arrest. Furthermore, we demonstrated that most apoptotic events induced by baccatin III were not coupled with G2/M arrest. Instead, these apoptotic events occurred predominantly in the cells in other phases of the cell cycle. Conclusion: Baccatin III, which contains the core taxane ring, is the fundamental piece of paclitaxel structure. The finding of baccatin III-induced apoptosis independent of cell cycle arrest, on the one hand, implies that the core taxane ring may play a critical role in inducing cell death and, on the other hand, suggests that paclitaxel might induce apoptosis from other phases of the cell cycle by a similar mechanism.
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  • 52
    ISSN: 1432-0851
    Keywords: Key words Immunotherapy ; MK-1 antigen ; Chimeric antibody ; ADCC ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mouse monoclonal antibody FU-MK-1, raised against a human gastric adenocarcinoma, recognizes a glycoprotein antigen (termed MK-1 antigen) present on most carcinomas and seems to be valuable in immunodiagnosis and immunotherapy of various cancers. In a recent study, we constructed a mouse/human chimeric antibody, designated Ch FU-MK-1, by fusing the FU-MK-1 VH and Vκ genes to the human Cγ1 and Cκ genes, respectively. In the present study, we tested combination immunotherapy of Ch FU-MK-1 with human lymphokine-activated killer (LAK) cells in vitro and in mice with severe combined immunodeficiency (SCID) bearing human MK-1-expressing tumors. In in vitro experiments, Ch FU-MK-1 effectively mediated antibody-dependent cell-mediated cytotoxicity (ADCC) against MK-1-expressing MKN-74 cells, which was completely blocked by an anti-FcR antibody. Since the apoptotic pathway as well as the necrotic pathway have been shown to be utilized in various cytotoxic effector mechanisms, we investigated the role of apoptosis in ADCC mediated by LAK cells and Ch FU-MK-1 against MKN-74 cells. The implication of the apoptosis during ADCC was demonstrated by means of both a terminal-deoxynucleotidyltransferase-mediated dUTP-biotin nick-end-labeling assay and a propidium iodide staining method. In vivo antitumor activity of combination treatment with LAK cells and Ch FU-MK-1 was estimated using SCID mice inoculated s.c. with MKN-74 cells. The i.v. administration of LAK cells and i.p. administration of Ch FU-MK-1 and interleukin-2 (IL-2) produced a marked growth inhibition of MKN-74 tumors in SCID mice. When the actual tumor weights were measured 16 days after initiation of treatment, more than 70% reduction was observed in the group receiving LAK cells plus Ch FU-MK-1 plus IL-2 as compared to the control untreated group. Together these results suggest that Ch FU-MK-1 may serve as a potentially useful immunotherapeutic reagent for human MK-1-expressing tumors.
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  • 53
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    International journal of colorectal disease 14 (1999), S. 201-211 
    ISSN: 1432-1262
    Keywords: Key words Inflammatory bowel disease ; TNBS rat model ; Resistant starch ; Absorption of short-chain fatty acids ; Butyrate functions ; Proliferation ; Apoptosis ; Matrix proteins ; Intestinal microflora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  These studies were performed to test the benefit of resistant starch on ulcerative colitis via prebiotic and butyrate effects. Butyrate, propionate, and acetate are produced in the colon of mammals as a result of microbial fermentation of resistant starch and other dietary fibers. Butyrate plays an important role in the colonic mucosal growth and epithelial proliferation. A reduction in the colonic butyrate level induces chronic mucosal atrophy. Short-chain fatty acid enemas increase mucosal generation, crypt length, and DNA content of the colonocytes. They also ameliorate symptoms of ulcerative colitis in human patients and rats injected with trinitrobenzene sulfonic acid (TNBS). Butyrate, and also to a lesser degree propionate, are substrates for the aerobic energy metabolism, and trophic factors of the colonocytes. Adverse butyrate effects occur in normal and neoplastic colonic cells. In normal cells, butyrate induces proliferation at the crypt base, while inhibiting proliferation at the crypt surface. In neoplastic cells, butyrate inhibits DNA synthesis and arrests cell growth in the G1 phase of the cell cycle. The improvement of the TNBS-induced colonic inflammation occurred earlier in the resistant starch (RS)-fed rats than in the RS-free group. This benefit coincided with activation of colonic epithelial cell proliferation and the subsequent restoration of apoptosis. The noncollagenous basement membrane protein laminin was regenerated initially in the RS-fed group, demonstrating what could be a considered lower damage to the intestinal barrier function. The calculation of intestinal short-chain fatty acid absorption confirmed this conclusion. The uptake of short-chain fatty acids in the colon is strongly inhibited in the RS-free group, but only slightly reduced in the animals fed with RS. Additionally, RS enhanced the growth of intestinal bacteria assumed to promote health. Further studies involving patients suffering from ulcerative colitis are necessary to determine the importance of RS in the therapy of a number of intestinal diseases and the maintenance of health.
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  • 54
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    Experimental brain research 124 (1999), S. 241-247 
    ISSN: 1432-1106
    Keywords: Key words Melatonin ; Kainate ; Glutathione ; Apoptosis ; Excitotoxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The anti-excitotoxic efficacy of the pineal hormone melatonin was investigated in kainate-injured brains of rats. Kainate (a glutamate-receptor agonist, 2.5 nmol in 1 µl) was directly injected to unilateral striatum. Melatonin (10 mg/kg) was administrated intraperitoneally 1 h before and 1, 3, and 5 h after intrastriatal kainate injection in adult Sprague-Dawley rats. Three days after kainate injection, a significant neuronal damage was found, as determined by Nissl staining and the TUNEL method, not only in the injected striatum, but also in the ipsilateral neighboring cortex. The kainate-induced cortical apoptotic neuronal death was significantly attenuated by treatment with melatonin compared with the vehicle control group. However, no detectable changes were observed in the contralateral side of the brain in either vehicle- or melatonin-treated rats. Moreover, the biochemical results indicated that kainate can indeed induce oxidative stress, such as a decrease in the content of total glutathione (GSH), oxidized glutathione (GSSG), and an increase in the ratio of GSSG/GSH in the striatum and cortex compared with the contralateral brain regions. In the kainate-injected striatum, melatonin did not reduce the oxidative stress, but in the neighborhood of injected area-cortex, kainate-induced oxidative stress was significantly reduced by melatonin. Enhancement of glutathione-peroxidase activity was induced by intrastriatal kainate injection, not only in the cortical area of control and melatonin-treated rats, but also in striatum of control rats. However, a large elevation was found in the melatonin-treated cortex. Taking the morphological and biochemical data together, the present results suggest that melatonin functions as an antioxidant by upregulating the glutathione antioxidative defense system, thereby reducing neuronal death caused by excitotoxicity and preventing the kainate-induced damage from spreading to adjacent brain regions.
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  • 55
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    Naunyn-Schmiedeberg's archives of pharmacology 359 (1999), S. 228-234 
    ISSN: 1432-1912
    Keywords: Key words Natural killer ; Pentoxifylline ; Macroangiopathic patients ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The methylxanthine derivative pentoxifylline, widely used in the treatment of vascular diseases, also has numerous immunological effects. In in vitro experiments, the human natural killer cell cytotoxicity was investigated in the presence of pentoxifylline. A clinical trial involved an investigation of the natural killer cell activity in patients to whom pentoxifylline had been administered for different periods. The natural cytotoxicity in macroangiopathic patients treated with pentoxifylline was compared with that in healthy controls and that in patients with vascular diseases who did not receive pentoxifylline therapy. A total of 62 macroangiopathic patients and 20 healthy controls were investigated. The natural killer cell activity in patients receiving pentoxifylline therapy for more than a year proved to be significantly lower (P〈0.005). The presence of vascular disease did not influence the natural killer activity. In the in vitro cytotoxicity reaction, pentoxifylline at a concentration of 100 µg/ml was found to suppress the natural killer cell cytotoxicity at any stage of the reaction. The influence of pentoxifylline on the natural killer cell activity was not due to inhibition of the expression of intercellular adhesion molecule-1. However, this drug significantly decreases (P〈0.05) the apoptosis of target cells. It is presumed that the suppressor effect of pentoxifylline on natural killer cell activity should be taken into consideration in the treatment of clinical diseases where this drug is administered chronically.
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  • 56
    ISSN: 1432-1963
    Keywords: Schlüsselwörter Epitheloides Hämangioendotheliom ; Leber ; Kindesalter ; Proliferation ; Apoptose ; Key words Epithelioid hemangioendothelioma ; Liver ; Childhood ; Proliferation ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary We report on a 12-year old boy suffering from malignant epithelioid hemangioendothelioma of the liver, which is a very rare tumor in childhood. The tumor was detected by ultrasound examination at the age of 10 and appeared at that time as a solitary intrahepatic nodular lesion. During the following 2 years multiple nodular lesions developed in both hepatic lobes. There were neither any suspect anamnestic findings nor abnormal clinical or laboratory data. The tumor showed the typical histomorphological, immunohistochemical, and ultrastructural features of this entity, which is usually seen in older patients. We investigated proliferative activity, apoptotic regulation, and expression of VEGF and VEGF-receptor flk-1 by means of immunohistochemical techniques. According to the known slow growth activity of these tumors we found only a few Ki-67 positive tumor cells. We did not detect any apoptotic cells using TUNEL technique. The positive immunoreaction of the tumor cells with antibodies against VEGF and VEGF-receptor flk-1 may indicate the regulation of tumor growth by angiogenetic factors. We present our findings together with a summary of the most important publications of recent years concerning these tumors.
    Notes: Zusammenfassung Bei einem 12 Jahre alten Jungen wurde ein im Kindesalter sehr seltenes malignes epitheloides Hämangioendotheliom der Leber diagnostiziert. Im Alter von 10 Jahren fiel erstmals sonografisch ein solitärer Leberrundherd auf, im Verlauf der nächsten zwei Jahre entwickelten sich multiple Rundherde in beiden Leberlappen. Die Anamnese des Patienten war hinsichtlich möglicher prädisponierender Faktoren unauffällig. Die klinischen und laborchemischen Parameter befanden sich im Normbereich. Der Tumor wies die für diese, üblicherweise bei Erwachsenen auftretenden Entität typischen histomorphologischen, immunhistochemischen und ultrastrukturellen Merkmale auf. Mittels immunhistochemischer Untersuchungen wurde das Tumorgewebe hinsichtlich Proliferationsaktivität, Apoptoseregulation und Expression angiogenetischer Faktoren (VEGF und VEGF-Rezeptor flk-1) untersucht. Bei bekanntermaßen langsamer Wachstumstendenz dieser Tumoren fand sich ein geringer Anteil Ki-67-positiver Tumorzellen. Mittels TUNEL-Technik wurden keine Apoptosen gefunden. Die positive Immunreaktion der Tumorzellen mit Antikörpern gegen VEGF und den VEGF-Rezeptor flk-1 deutet auf eine Regulation des Tumorwachstums durch angiogenetische Faktoren hin. Die Ergebnisse werden in Verbindung mit einer Zusammenstellung der wichtigsten Publikationen der letzten Jahre über diese seltenen Tumoren diskutiert.
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  • 57
    ISSN: 1432-0983
    Keywords: Key words Fission yeast ; Caspases ; Bcl-2 ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two pro-apoptotic proteases, caspase-1 and caspase-3, have been expressed as full-length proteins in the fission yeast Schizosaccharomyces pombe. Both proteins autoprocess to generate the corresponding active enzyme and both are lethal to the yeast cell. Lethality is due to catalytic activity since the expression of the inactive mutant forms of both caspases does not result in an obvious phenotype. Caspase-expressing yeast can be rescued by co-expression of the baculovirus protein p35, a known inhibitor of the caspase family. Co-expression of Bcl-2, another anti-apoptotic protein, does not prevent the cell death induced by either caspase. However, Bcl-2 is itself cleaved by both caspase-1 and caspase-3 at two adjacent recognition sites, YEWD31′A and DAGD34′V respectively, immediately downstream from the N-terminal BH4 domain, a region of Bcl-2 which is essential for its anti-apoptotic activity; similar cleavage of Bcl-2 by caspases has been demonstrated in mammalian cells. Hence, key elements of the apoptotic pathway can be reliably reconstituted in fission yeast, opening the way to exploit yeast in order to study the control of apoptosis. Furthermore, the activity of caspase-3, although not caspase-1, can be demonstrated in vitro using chromogenic substrates. This offers the possibility of using caspase-producing strains of yeast to screen for chemical inhibitors either in vivo or in vitro.
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  • 58
    ISSN: 1432-0851
    Keywords: Key words NK cells ; IL-2 ; Fas ; FasL ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The Fas/Fas-ligand (FasL) system seems to play a key role in regulating immunoresponses. Highly purified CD56+CD3− natural killer (NK) cells were found to be resistant to the apoptosis-inducing Fas mAb CH11 in the absence or in the presence of interleukin-2 (IL-2) for up to 3 days. However, NK cells activated with IL-2 for 3 days became apoptotic following combined treatment with CH11 and actinomycin D, suggesting the presence of an intact apoptotic machinery. In contrast, NK cells cultivated in IL-2 for 6 days became sensitive to CH11-induced apoptosis without addition of actinomycin D. At this time, a pronounced up-regulation of the Fas protein on the NK cell membrane was detected. By using reverse transcription/polymerase chain reaction it was found that the anti-apoptotic gene FLIP was strongly expressed in NK cells for up to 6 days of IL-2 stimulation. After day 6, a time-dependent decrease in the expression of FLIP was observed concomitantly with increased sensitivity for Fas-mediated apoptosis. The amount of apoptotic and necrotic NK cells in the presence of IL-2 increased in a time-dependent manner, reaching 40% at day 6 of culture. The amount of apoptotic and necrotic NK cells was reduced in the presence of Fas-Fc protein. In addition, IL-2 stimulated the NK cells to release soluble FasL in a time-dependent manner, whereas membrane FasL did not seem to increase in a similar manner. These results indicate that Fas/FasL interactions are involved in the down-regulation of IL-2-activated human NK cells.
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  • 59
    ISSN: 1432-0851
    Keywords: Key words Tumour antigen ; MUC1 ; T cell ; immunosuppression ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The in vitro anti-proliferative properties of various supernatants from MUC1-expressing cell lines and of purified preparations of MUC1 were evaluated. We have observed that supernatants from the MUC1- and MUC3-positive cell line T47D, but not from the MUC1- and MUC4-positive cell line MCF7, were able to inhibit proliferation of cells from various haematopoietic cell lines. Although the activity of T47D supernatants could be abrogated by immunodepletion of MUC1, immunopurified MUC1 from T47D was unable to inhibit cell proliferation. Significantly, supernatants from mouse 3T3 cells transfected with a secreted form of MUC1 or from BHK-21 cells infected with a recombinant vaccinia virus coding for the secreted form of MUC1, as well as preparations of purified MUC1 from bile or urine, were likewise unable to inhibit T cell proliferation. Surprisingly, a crude mixture of bile mucins had a suppressive effect on T cell growth. Our results suggest that other molecules, such as amino sugars or other mucins, which can associate with MUC1, are likely to be responsible for the observed anti-proliferative effects of T47D cells.
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  • 60
    ISSN: 1432-0851
    Keywords: Key words CD95L ; FasL ; Renca ; Apoptosis ; Tumor growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The CD95/CD95 ligand (CD95L) system plays an important role in the induction of lymphoid apoptosis and has been implicated in the suppression of immune responses. In this system, two murine CD95L-transfected renca clones and a control renca clone transfected only with the vector were implanted into the subcapsule of the left kidney of Balb/c and Balb/c nude mice. Both CD95L-expressing and control renca clones formed macroscopic tumors in all of the Balb/c and Balb/c nude hosts 14 days after implantation. Growth of tumors of murine CD95L-transfected renca cells was significantly better than that of control renca cells in Balb/c mice, while the growth advantage of CD95L transfectants was not observed in Balb/c nude mice. Lymphocytes underwent apoptosis mainly in the periphery of the CD95L-expressing tumors but not in control tumors grown in Balb/c mice, while lymphocytes undergoing apoptosis were not observed in CD95L-expressing tumors or in control tumors grown in Balb/c nude mice. Neutrophilic recruitment was rarely observed in CD95L-expressing or control tumors. CD95L expressed on renca cells possibly suppressed immune responses against renca tumors by inducing apoptosis of the infiltrating lymphocytes. However, CD95L-expressing renca cells did not form tumors in the renal subcapsule of allogeneic C3H/HeJ mice.
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  • 61
    ISSN: 1432-0738
    Keywords: Key words Doxorubicin ; Apoptosis ; Testicular toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To clarify whether apoptosis is involved in doxorubicin (DXR)-induced testicular toxicity and to identify the target germ cell type, adult Sprague-Dawley rats were treated with a single intravenous dose of DXR (8 or 12 mg/kg) and euthanized at 3, 6, 12, 24, and 48 h subsequently. Histologically, germ cell degeneration was first found 6 h after dosing in meiotically dividing spermatocytes and early round spermatids of seminiferous tubules at stage I, and subsequently observed in spermatogonia at stages I–VI showing ultrastructural characteristics of apoptosis. Coincident with the appearance of morphological changes, degenerating germ cells were shown to be undergoing apoptosis as revealed by in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). The frequency of TUNEL-labeled germ cells increased in a stage- and cell type-specific manner, the peak of frequency gradually progressing from stage I of seminiferous tubules to later stages with time after dosing, suggesting that the damaged germ cells, especially spermatogonia, gradually underwent the processes leading to apoptosis. DNA laddering on gel electrophoresis was apparent 24 and 48 h after dosing. The results demonstrate that apoptosis plays an important role in the induction of testicular toxicity caused by DXR with meiotically dividing spermatocytes and type A and intermediate spermatogonia as highly vulnerable target cells.
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  • 62
    ISSN: 1432-0738
    Keywords: Key words Allylnitrile ; Apoptosis ; Behavioral abnormalities ; Habenula ; Mice brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A single dose of allylnitrile in mice might induce persistent behavioral abnormalities, of which the mechanism is not yet known. The present study was undertaken to explore the relationship between behavioral abnormalities and pathological changes in the brain of mice following exposure to allylnitrile. Exposure to allylnitrile (63, 84, and 112 mg/kg, p.o.) resulted in dose-dependent changes in behavioral abnormalities, including increased locomotor activity, circling, retropulsion, head twitching, and alteration in reflexive behavior, which appeared at day 2 postdosing and were persistent throughout the experimental period (60 days) at the higher dose levels. Allylnitrile produced neuronal retraction including hyperchromasia of the nuclei in the raphe nuclei, cerebral cortex, hypothalamus, hippocampal CA1 and dentate gyrus later than 30 days. No gliosis was observed in these regions. Not all but a significant number of neurons in the hippocampal CA1, medial habenula and raphe nuclei were immunoreactive to CPP32 (Caspase-3) even at day 2. These neurons were also positive to Hoechst 33258 staining, indicating allylnitrile caused apoptotic changes in specific neurons when neuronal behaviors became apparent. These apoptotic changes were persistent even in the area without neuronal contraction such as medial habenula. However, almost all neurons in these areas were also positive to terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling (TUNEL). It is conceivable that allylnitrile caused apoptotic changes in neurons but did not always lead them to cell death immediately. Moreover, even when neuronal contraction resulted in retention of behavioral abnormalities, onset of these abnormalities seems to be associated with the impairment in the habenulo-raphe relay due to activation of apoptotic cascade in neurons.
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  • 63
    ISSN: 1432-1831
    Keywords: Key words Verocytotoxin ; Verocytotoxin-producing Escherichia coli ; Hemolytic uremic syndrome ; Renal proximal tubular cell ; Apoptosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Verocytotoxin 1 and 2 (VT1 and 2) produced by verocytotoxin-producing Escherichia coli have been considered to play an important role in the pathogenesis of glomerular and tubular damage in the epidemic form of hemolytic uremic syndrome (HUS). VTs are known to be cytotoxic to culture cells by inhibiting cellular protein synthesis. In this in vitro study, the mechanism(s) of tubular damage in HUS and the ability of VT1 to induce apoptosis in normal human renal proximal tubular epithelial cells (HRPTEC) were examined. VT1 markedly reduced cell viability of HRPTEC and rapidly inhibited overall protein synthesis. VT1 directly induced apoptotic cell death in HRPTEC in a dose- and time-dependent fashion, and co-incubation with tumor necrosis factor-α enhanced the VT1-induced apoptosis. These results suggest that apoptosis induced by VT1, possibly in concert with host cytokines, in renal tubular cells may contribute to the tubular damage in HUS.
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  • 64
    ISSN: 1569-8041
    Keywords: chromosomal aberrations ; gene expression ; oncogenes ; pancreatic cancer ; tumor suppressor genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aim: The present review summarizes our strategies aimed at identifying and characterizing genetic alterations occuring at the transcriptional and chromosomal level in pancreatic cancer. Methods: To study transcriptional alterations we have used a number of techniques including modified versions of differential hybridizations and cDNA-RDA (representational difference analysis). Comparative genomic hybridization (CGH) was used to study chromosomal aberrations occuring in pancreatic cancer tissues. Results: The study of transcriptional alterations led to the identification of more than 500 genes with differential expression in pancreatic cancer. The sum of these alterations represented the first expression profile characteristic for pancreatic tumors. The CGH analysis allowed the identification of a number of chromosomal regions containing putative tumor suppressor genes or oncogenes. These regions are presently being characterized at the molecular level. In a first approach the myb-oncogene was identified as the relevant oncogene of an amplification on 6q occurring in up to 10% of pancreatic cancer patients. Conclusions: Genes isolated in both approaches represent potential new disease genes for pancreatic cancer and are at present being characterized by individual or serial analysis.
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  • 65
    ISSN: 1573-4919
    Keywords: microbodies ; diabetes mellitus ; steroid hormone receptor ; β-oxidation ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract To determine whether the increased fatty acid β-oxidation in the peroxisomes of diabetic rat liver is mediated by a common peroxisome proliferation mechanism, we measured the activation of long-chain (LC) and very long chain (VLC) fatty acids catalyzed by palmitoyl CoA ligase (PAL) and lignoceryl CoA ligase and oxidation of LC (palmitic acid) and VLC (lignoceric acid) fatty acids by isotopic methods. Immunoblot analysis of acyl-CoA oxidase (ACO), and Northern blot analysis of peroxisome proliferator-activated receptor (PPAR-α), ACO, and PAL were also performed. The PAL activity increased in peroxisomes and mitochondria from the liver of diabetic rats by 2.6-fold and 2.1-fold, respectively. The lignoceroyl-CoA ligase activity increased by 2.6-fold in diabetic peroxisomes. Palmitic acid oxidation increased in the diabetic peroxisomes and mitochondria by 2.5-fold and 2.7-fold, respectively, while lignoceric acid oxidation increased by 2.0-fold in the peroxisomes. Immunoreactive ACO protein increased by 2-fold in the diabetic group. The mRNA levels for PPAR-α, ACO and PAL increased 2.9-, 2.8- and 1.6-fold, respectively, in the diabetic group. These results suggest that the increased supply of fatty acids to liver in diabetic state stimulates the expression of PPAR-α and its target genes responsible for the metabolism of fatty acids.
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  • 66
    ISSN: 1573-4919
    Keywords: regucalcin ; Ca2+-binding protein ; protein kinase C ; Ca2+signaling ; gene expression ; H4-II-E hepatoma cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The expression of hepatic Ca2+-binding protein regucalcin in the cloned rat hepatoma cells (H4-II-E) was investigated. The change in regucalcin mRNA levels was analyzed by Northern blotting using rat liver regucalcin complementary DNA (0.9 kb of open reading frame). Regucalcin mRNA was expressed in H4-II-E hepatoma cells. This expression was clearly stimulated in the presence of serum (10% fetal bovine serum). Bay K 8644 (2. 5 × 10-6 M), a Ca2+ channel agonist, significantly stimulated regucalcin mRNA expression in the absence or presence of 10% serum. Dibutyryl cyclic AMP (10-3 M) did not have a stimulatory effect on the regucalcin mRNA expression. The presence of phorbol 12-myristate 13-acetate (PMA; 10-6 M) or estrogen (10-8 M) caused a significant increase in regucalcin mRNA levels in the hepatoma cells cultured in serum-free medium, while insulin (5 × 10-9 M) or dexamethasone (10-6 M) had no effect. Bay K 8644-stimulated regucalcin mRNA expression in the hepatoma cells was completely blocked in the presence of trifluoperazine (10-5 M), an antagonist of calmodulin, or staurosporine (10-7 M), an inhibitor of protein kinase C. The stimulatory effect of PMA was clearly inhibited in the presence of stauroporine. The present study demonstrates that regucalcin mRNA is expressed in the transformed H4-II-E hepatoma cells, and that the expression is stimulated through Ca2+-dependent signaling factors.
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  • 67
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    Molecular and cellular biochemistry 199 (1999), S. 189-200 
    ISSN: 1573-4919
    Keywords: lung ; cancer ; urokinase ; receptor ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The urokinase-type plasminogen activator (uPA) interacts with its receptor (uPAR) to promote proteolysis as well as cell proliferation and migration. These functions contribute to the pathogenesis of neoplastic growth and invasiveness. Expression of uPAR in tumor extracts also inversely correlates with prognosis in many forms of cancer. In this study, we sought to determine if differences in uPAR expression were distinguishable between cultured human lung carcinoma and malignant mesothelioma subtypes. We also sought to determine if, as in malignant mesothelioma cells, uPAR expression is regulated at the posttranscriptional level in cultured malignant lung carcinoma cells. Using 125I-uPA binding and ligand blotting techniques, uPAR was expressed by phenotypically diverse lung carcinoma cell lines, including the H460, H157 and H1395 non-small cell lines and the H146 small cell lung carcinoma line. Increased uPAR expression was also detected in spindle-shaped (M33K) and epithelioid (M9K and MS-1) malignant mesothelioma cells. Selected mediators, including TGF-β, TNF-α, LPS and PMA, uniformly enhanced uPAR expression in each of the tumor cell lines. Steady state uPAR mRNA expression was determined by RNase protection assay and correlated directly with the changes in cell surface uPAR expression. By gel mobility shift and UV-cross linking assays, a uPAR mRNA binding protein (uPAR mRNABp) implicated in the posttranscriptional control of message stability, was identified in each of the cell lines. Expression of uPAR and its message in cultured lung carcinoma and malignant mesothelioma cells is similarly influenced by effectors present in the tumor microenvironment. Regulation of the uPAR message occurs at the posttranscriptional level in cultured small and non-small cell lung carcinoma cells as well as spindle-shaped and fibrous malignant mesothelioma cell lines. Posttranscriptional regulation of uPAR in all these cells involves the interaction of the uPAR mRNABp with uPAR mRNA, which promotes uPAR mRNA destabilization.
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  • 68
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    Molecular and cellular biochemistry 201 (1999), S. 111-123 
    ISSN: 1573-4919
    Keywords: complement factor I ; TPA ; protein kinase C ; gene expression ; Hep G2 cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This study examined the role of the protein kinase C (PKC) signalling pathway in the regulation of expression of human complement factor I (CFI) gene. The production of CFI by Hep G2 cells was enhanced in a dose- and time-dependent fashion by 12-O-tetradecanoyl-1,2-phorbol 13-acetate (TPA), a potent PKC activator. 4α-phorbol didecanoate, an inactive phorbol ester, had no effect on CFI synthesis. The TPA-dependent increase in CFI secretion was correlated with an increase in CFI mRNA levels. Forskolin, a cAMP-inducing agent, augmented the TPA response. W7, an inhibitor of protein kinase A and genistein, an inhibitor of protein tyrosine kinase(s) both did not prevent the increase in CFI expression mediated by TPA. However, calphostin C, a specific inhibitor of PKC, abolished the TPA-induced increase in CFI mRNA levels. Down regulation of intracellular PKC levels by prior exposure of Hep G2 cells to a high concentration of TPA also blocked the increase in CFI mRNA levels induced by TPA suggesting that the TPA effects were mediated via activation of PKC. mRNA decay studies indicated that the half-life of CFI mRNA in TPA-induced cells was not significantly different from control. Nuclear run-on transcriptional assays on the other hand demonstrated that whereas the CFI gene is transcribed under basal conditions in Hep G2 cells, TPA induced a 3-4 fold increase in the transcription rate of CFI gene in 24 h. The transcription rate of GAPDH gene did not change, indicating that the effects were not general on gene transcription. Transient transfections of Hep G2 cells with chloramphenicol acetyltransferase reporter gene (CAT) constructs containing a series of sequential 5′ deletions of the CFI promoter and CAT assays showed that the sequence between -136 and -130, containing an AP-1 consensus sequence (TGAGTCA) was required for the TPA response. This observation was substantiated by the finding that mutation of this AP-1 site to TttaTCA or TtAtcCA abolished the TPA responsiveness. The enhancement of the activity of transfected chimeric CAT constructs by TPA was abrogated by calphostin C and by pyrrolidine dithiocarbamate (an inhibitor of NF-κB and AP-1 transactivation). These results indicate that TPA regulation of CFI gene requires PKC signalling and is mediated by via a TPA response element (TRE) in the CFI promoter region located at -136/-130 and involves the transactivation of AP-1 and NF-κB transcription factors. We suggest that PKC may be one of the intracellular pathways that control CFI gene expression and that cellular processes (involving growth factors, hormones, cytokines etc.) that activate PKC may upregulate the expression of the CFI gene.
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  • 69
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; Ca2+-ATPase ; brain microsomes ; aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The expression of calcium-binding protein regucalcin and its effect on the microsomal Ca2+-ATPase activity in rat brain tissues was investigated. The expression of regucalcin mRNA was demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) analysis in brain tissues using rat regucalcin-specific primers. Regucalcin concentration in the brain tissues was about 5 × 10-9 M as measured using enzyme-linked immunoadsorbent assay (ELISA), and this level was lowered with increasing age (50 weeks old). The presence of regucalcin (10-9 to 10-7 M) in the enzyme reaction mixture caused a significant decrease in Ca2+-ATPase activity in the brain microsomes of young rats (5 weeks old). Meanwhile, the enzyme activity was not significantly altered by the addition of calmodulin (1 or 50 μg/ml), calbindin (1 or 10 μg/ml), and S-100 A protein (5 or 25 μg/ml), which are other Ca2+-binding proteins in rat brain. The effect of regucalcin to inhibit microsomal Ca2+-ATPase activity was weakened in the brain of rats with increasing age (50 weeks old). The present study demonstrates that regucalcin is expressed in the brain, and that it can uniquely inhibit Ca2+-ATPase activity in the brain microsomes of rats. The findings suggest that regucalcin plays a role in the regulation of microsomal Ca2+-ATPase activity in rat brain tissues.
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  • 70
    ISSN: 1573-4919
    Keywords: mechanical stretch ; smooth muscle cells ; differential display ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Physical forces induce profound changes in cell phenotype, shape and behavior. These changes can occur in vascular structures as a result of pressure overload and their effects can be seen in atherosclerotic vessels in which smooth muscle cells have undergone hyperplastic and hypertrophic changes. At the molecular level, mechanical stimuli are converted into chemical ones and lead to modulation of gene expression and/or the activation of a new repertoire of genes whose encoded proteins help the cells to adapt to their microenvironment. In this study, we have used a two primer-based mRNA differential display technique to identify candidate mechano-responsive genes in pulmonary artery smooth muscle cells. As compared to the original method described by Liang and Pardee, this technique uses two arbitrary primers instead of an anchored oligo(dt) plus an arbitrary primer in the polymerase chain reaction. The chief advantages of these modifications are an increase in the efficiency of the amplification and in the identification of differentially expressed clones. Using this approach, we compared the pattern of expressed genes in cells cultured under static conditions with those in cells that were mechanically stretched (1 Hz) for 24 h in a well-defined in vitro mechanical system. Three candidate genes that showed reproducible differences were chosen for further characterization and cloning. One clone was under expressed in stretched cells and had a DNA sequence with 90% homology to the human fibronectin gene. Two other clones were highly expressed in stretched cells and had a 92% and a 83% sequence homology with human platelet-activating factor (PAF) receptor and rat insulin-like growth factor-I (IGF-I) genes respectively. Northern blot analysis confirmed low levels of fibronectin mRNA transcripts in stretched cells. In contrast, accumulation of PAF receptor mRNA occurred 30 min after mechanical stretch was initiated whereas IGF-I mRNA levels peaked at 8 h. Both mRNA levels were sustained for up to 24 h of mechanical stretching. These results demonstrate the usefulness of the two primer-based mRNA differential display that enabled us to identify and characterize alterations at the level of gene expression among matrix proteins, G-protein coupled receptors and growth factors, each of whose response to mechanical strain is different. A more complete understanding of these responses will provide further insight into the pathologic processes associated with hypertension and atherosclerosis.
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  • 71
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    Medical microbiology and immunology 187 (1999), S. 221-226 
    ISSN: 1432-1831
    Keywords: Key wordsToxoplasma gondii ; Apoptosis ; Actinomycin D ; HL-60 ; Intracellular survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Intracellular microorganisms have to rely on the integrity of their host cells to persist. We, therefore, investigated the effect of infections with different Toxoplasma gondii strains on apoptosis of human-derived HL-60 cells at the single cell level. Infection with either mouse-avirulent (NTE strain) or virulent parasites (RH strain) did not induce apoptosis of HL-60 cells as compared to uninfected controls. In contrast, treatment with actinomycin D (act D) led to apoptosis in 15–25% of the cells. However, concomitant infection with T. gondii clearly abrogated act D-induced apoptosis. This was especially apparent in those host cells that were actually infected; in these parasite-positive cells the rate of apoptosis decreased by 82.8±4.3% (mean±SEM, P=0.017, Student's t-test) and 91.7±3.4% (P=0.024) after infection with either the NTE or the RH strain, respectively. Inhibition of host cell apoptosis was similarly observed in cells which had been invaded by UV-irradiated, non-replicating parasites (P=0.001, Student's t-test). However, incubation with heat-killed parasites or T. gondii lysates did not abrogate act D-induced apoptosis. In conclusion, inhibition of apoptosis by living, but not necessarily replicating T. gondii may facilitate parasite survival and persistence within its host cell.
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  • 72
    ISSN: 1432-2307
    Keywords: Key words Proliferation ; Apoptosis ; Ki-67 antigen ; Prognosis ; Retinoblastoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The balance between proliferation and cell death is the major determinant of tumour growth. We analysed the proliferative and apoptotic indices (PI and AI, respectively) of 33 children with retinoblastoma. PI and AI were assessed by immunohistochemistry for Ki-67 antigen and TUNEL staining, respectively. The mean PI was 21.0±21.1%, and higher PI was associated with more advanced tumour stage (P〈0.0001) and poor clinical outcome (P〈0.05). Patients in whom amplified N-myc oncogene was found (n=6) determined by the multiplex polymerase chain reaction tended to have a higher PI (37.6±27.2%) than those without amplified N-myc (n=27; PI=17.3±18.1). A PI value of over 40% was clearly associated with an unfavourable prognosis. The AI, however, did not correlate with any of the other variables analysed. The findings suggest that proliferation, but not apoptosis, is of critical significance in retinoblastoma biology. PI, as determined by the Ki-67 antigen labelling index, seems to be a relevant histopathological parameter that can predict the clinical outcome of retinoblastoma.
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  • 73
    ISSN: 1432-0878
    Keywords: Key words Adenosine ; Nucleosides ; Neurotoxicity ; Embryogenesis ; Apoptosis ; Chick
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Previous work has shown that nucleosides produce apoptosis in sympathetic ganglion (SG) cells in vitro. The present study examined the effects of nucleosides on the development of the chick embryo in vivo with special attention to the SG and the optic tectum of the central nervous system. In the presence of an adenosine deaminase inhibitor, adenosine and 2’-deoxyadenosine (2’-dAdo) produced different toxicity patterns: both adenosine and 2’-dAdo were toxic to E3 embryos, but only 2’-dAdo was toxic at later stages (E6 1/2, E11). Dosage experiments on E6 1/2 embryos showed that adenosine was less toxic than 2’-dAdo and that 2’-dAdo in sublethal doses was teratogenic. We also examined the effects of 2’-dAdo on embryonic chicken SG and optic tectum in vivo to determine whether sublethal doses of 2’-dAdo produced cell death in these centers on E6 1/2 and 10. In the E6 1/2 SG, 2’-dAdo produced significant neuron loss (83%) and a decrease in SG volume (65%); however, at E10, there was only minor cell loss (7%) and no significant change in SG volume. In the optic tectum at E6 1/2, cell loss was confined mainly to the tectal ventricular zone, but there was little sign of cell loss in this organ at E10. Since cell production is vigorous in the SG and optic tectum at E6 1/2 but relatively low at E10, 2’-dAdo appears to work by stopping cell proliferation. The ineffectiveness of 2’-dAdo at E10 may result from the lethality of 2’-dAdo to the embryo at low concentrations (30 µM) in vivo, well below the apoptosis-inducing concentrations employed in vitro (100–300 µM). These data extend previous findings showing that purine and pyrimidine metabolism plays an important role in development.
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  • 74
    ISSN: 1871-4528
    Keywords: Solanum tuberosum L. ; tuberisation ; extensin ; acyl carrier protein thioesterase ; high mobility group protein ; gene expression ; plant development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In screening to isolate a full-length copy of a previously isolated cDNA clone, a further three cDNAs were also isolated from a library prepared from sub-apical swelling-stolon tissue of potato (Solanum tuberosum L.). Sequence analysis showed these clones to be similar to extensin-like protein genes, acyl carrier protein thioesterase genes and high mobility group protein genes, respectively. A further cDNA, isolated by subtractive hybridisation, was similar to a tomato cDNA previously isolated on the basis of its down-regulation following nematode infection. While all the newly isolated genes were expressed in swelling stolons, for most, maximal expression was seen to be in stem tissue. Possible roles for these genes in the development of potato plants are discussed, as is the significance of gene expression in stems and stolons to the process of tuberisation.
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  • 75
    ISSN: 1573-9368
    Keywords: transgenic mice ; prolactin ; mammary gland ; gene expression ; Stat5 ; β-globin insulator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to establish a possible correlation between in vitro prolactin induction and the transcriptional activity of mammary gene promoters in transgenic mice, a functional Stat5-binding site was created by means of site-directed mutagenesis at position −70 on a 560 bp murine α-lactalbumin promotor linked to a CAT reporter gene. Surprisingly, the wild-type promoter was constitutively active in vitro and could not be induced by prolactin. Introducing the proximal Stat5 site abolished this constitutive activity and resulted in prolactin dependence in both CHO-K1- and HC11-transfected cells. In transgenic mice, both the frequency of lines expressing the transgene and the prevalence of mid to late pregnancy expression were increased.
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  • 76
    ISSN: 1573-0778
    Keywords: CHO cells ; gene expression ; kinetic model ; protein secretion ; transcription ; translation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The elevation of expression levels for secreted glycoproteins by gene amplification in mammalian cells shows a saturation behavior at high levels of gene amplification. At high expression levels a drop in the secretion efficiency for the recombinant protein occurs (Schröder and Friedl, 1997), coinciding with the appearance of misfolded protein in the cell. In this communication we investigated whether additional limitations exist at the levels of transcription and translation. Four Chinese hamster ovary (CHO) cell lines expressing different amounts of human antithrombin III (ATIII) were used as a model system. A tenfold increase in the ATIII cDNA copy number from the lowest to the highest producing cell line coincided with a 38-fold increase in ATIII mRNA levels, and an 80-fold increase in the amount of intracellular ATIII levels. The data was analyzed using a simple kinetic model. The following conclusions were derived: I. The transcriptional activity for the recombinant protein is not saturated. II. Translation itself is not saturated either, but may be downregulated as secretion efficiency drops. III. Two explanations for the previously reported drop in secretion efficiency for the recombinant protein with increasing expression level are possible: A. Protein degradation is an alternative fate for translated ATIII and the fraction of ATIII degraded after translation increases as expression level is increased. B. Translation is downregulated as the secretory apparatus becomes exhausted to maintain cell viability.
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  • 77
    ISSN: 1573-0778
    Keywords: cardiogenesis ; cell differentiation ; gene expression ; mouse embryonic stem cells ; myogenesis ; neurogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Embryonic stem cells, totipotent cells of the early mouse embryo, were established as permanent cell lines of undifferentiated cells. ES cells provide an important cellular system in developmental biology for the manipulation of preselected genes in mice by using the gene targeting technology. Embryonic stem cells, when cultivated as embryo-like aggregates, so-called ‘embryoid bodies’, are able to differentiate in vitro into derivatives of all three primary germ layers, the endoderm, ectoderm and mesoderm. We established differentiation protocols for the in vitro development of undifferentiated embryonic stem cells into differentiated cardiomyocytes, skeletal muscle, neuronal, epithelial and vascular smooth muscle cells. During differentiation, tissue-specific genes, proteins, ion channels, receptors and action potentials were expressed in a developmentally controlled pattern. This pattern closely recapitulates the developmental pattern during embryogenesis in the living organism. In vitro, the controlled developmental pattern was found to be influenced by differentiation and growth factor molecules or by xenobiotics. Furthermore, the differentiation system has been used for genetic analyses by ‘gain of function’ and ‘loss of function’ approaches in vitro.
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  • 78
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    Cytotechnology 30 (1999), S. 71-83 
    ISSN: 1573-0778
    Keywords: gene expression ; HEK293(EBNA) cells ; serum-free ; transient transfection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In order to establish a simple and scaleable transfection system we have used the cationic polymer polyethylenimine (PEI) to study transient transfection in HEK293 and 293(EBNA) cells grown in serum-free suspension culture. The transfection complexes were made directly within the cell culture by consecutively adding plasmid and PEI (direct method). Alternatively, the DNA-PEI transfection complexes were prepared in fresh medium (1/10 culture volume) and then added to the cells (indirect method). The results of this study clearly show that the ratio of PEI nitrogen to DNA phosphate is very important for high expression levels. The precise ratio is dependent on the DNA concentration. For example, using 1 μg/ml DNA by the indirect method, the ratio of optimal PEI:DNA was about 10–13:1. However, the ratio increases to 33:1 for 0.1–0.2 μg/ml DNA. By testing several different molecular weights of the polycationic polymer we could show that the highest transfection efficiency was obtained with the PEI 25 kDa. Using PEI 25 kDa the indirect method is superior to the direct addition because significantly lower DNA concentrations are needed. The expression levels of the soluble human TNF receptor p55 are even higher at low DNA compared to 1 μg/ml plasmid. The EBV-based pREP vectors gave better transient gene expression when used in 293(EBNA) cells compared to HEK293 cells in suspension culture. No differences in expression levels in the two cell lines were observed when the pC1 (CMV)-TNFR was used. In conclusion, PEI is a low-toxic transfection agent which provides high levels of transient gene expression in 293(EBNA) cells grown in serum-free suspension culture. This system allows highly reproducible, cost-effective production of milligram amounts of recombinant proteins in 2–5 l spinner culture scale within 3–5 days. Fermentor scale experiments, however, are less efficient because the PEI-mediated transient tranfection is inhibited by conditioned medium.
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  • 79
    ISSN: 1573-0778
    Keywords: cell cycle ; CHO ; flow cytometry ; gene expression ; synchronisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Understanding the relationships between cell cycle and protein expression is critical to the optimisation of media and environmental conditions for successful commercial operation of animal cell culture processes. Using flow cytometry for the analysis of the early phases of synchronised batch cultures, the dependency of product expression on cell cycle related events has been evaluated in a recombinant CHO cell line. Although the production of recombinant protein is initially found to be cell cycle related, the maximum specific protein productivity is only achieved at a later stage of the exponential phase which also sees a maximum in the intracellular protein concentration. Subsequent work suggests that it is the batch phase/medium composition of cultures which is the major determinant of maximum specific productivity in this cell line. Furthermore the effect of the positive association between S phase and specific productivity is subordinate to the effect of batch phase/medium composition on the specific productivity of batch cultures.
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  • 80
    ISSN: 1573-7276
    Keywords: gene expression ; immunohistochemistry ; mRNA DD ; neoplasia metastasis ; RAB5A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract For the sake of better understanding the molecular mechanism of neoplasia, we have used the mRNA differential display technique to analyze two human lung adenocarcinoma cell lines, AGZY83-a and Anip973. Anip973 was isolated from AGZY83-a, but manifested much higher metastatic potential than the parent line. We found that a significant differential cDNA fragment in Anip973 was over-expressed, then over-expressed cDNA fragment was cloned and sequenced. It showed that the over-expressed cDNA in Anip973 was RAB5A cDNA. And the RAB5A cDNA sequence was corresponding between the two cells. To determine whether RAB5A may be differentially expressed in the two human lung adenocarcinoma cells at protein level, we further detected RAB5A protein in the two cells by using immunofluorescent method. RAB5A protein was upregulated in highly metastatic Anip973. We also detected the difference in RAB5A gene expression at RNA level in human non-small cell lung carcinoma by RT-PCR. Using immunohistochemical staining, we also examined RAB5A change at protein level in 45 cases human non-small cell lung carcinoma paraffin sections. The results proved the evidence of upregulation of RAB5A in malignant tumor, indicated over-expression of RAB5A gene was correlated with the malignant degree and metastatic potential of lung cancer(χ2 test, p 〈0.01). The RAB5A gene is a member of RAS superfamily, which can transcribe GTP-binding protein that plays an important role in signal transduction of protein trafficking at the cell surface and GDP/GTP cycle in the regulation of endocytotic membrane traffic. Thus our results indicated that over-expression of the RAB5A gene was involved in the process of transformation from AGZY83-a to the higher metastatic cell line Anip973. The result may be a powerful experimental evidence that over-expression of RAB5A gene associated with neoplasia metastasis.
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  • 81
    ISSN: 1573-7365
    Keywords: glutamine synthetase ; gene expression ; portacaval anastomosis ; hepatic encephalopathy ; liver ; skeletal muscle ; ammonia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of chronic liver insufficiency resulting from end-to-side portacaval anastomosis (PCA) on glutamine synthetase (GS) activities, protein and gene expression were studied in brain, liver and skeletal muscle of male adult rats. Four weeks following PCA, activities of GS in cerebral cortex and cerebellum were reduced by 32% and 37% (p〈0.05) respectively whereas GS activities in muscle were increased by 52% (p〈0.05). GS activities in liver were decreased by up to 90% (p〈0.01), a finding which undoubtedly reflects the loss of GS-rich perivenous hepatocytes following portal-systemic shunting. Immunoblotting techniques revealed no change in GS protein content of brain regions or muscle but a significant loss in liver of PCA rats. GS mRNA determined by semi-quantitative RT-PCR was also significantly decreased in the livers of PCA rats compared to sham-operated controls. These findings demonstrate that PCA results in a loss of GS gene expression in the liver and that brain does not show a compensatory induction of enzyme activity, rendering it particularly sensitive to increases in ammonia in chronic liver failure. The finding of a post-translational increase of GS in muscle following portacaval shunting suggests that, in chronic liver failure, muscle becomes the major organ responsible for the removal of excess blood-borne ammonia.
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  • 82
    ISSN: 1573-7365
    Keywords: Oligodendrocyte cultures ; glucose ; gene expression ; malic enzyme ; membrane synthesis ; myelination ; undernutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have previously demonstrated that the developmental upregulation of myelin-specific genes in mixed glial cultures is strongly attenuated by hypoglycemia. The present study was designed to evaluate the effect of hypoglycemia on differentiation-dependent upregulation of myelin genes in purified oligodendrocyte cultures. The expression of major myelin protein genes, i.e., proteolipid protein (PLP), basic protein (BP) and myelin associated glycoprotein (MAG) were monitored by Northern blot analysis. In control cultures maintained at 6 mg/ml of glucose, the expression of all the genes upregulated rapidly, and plateaued at approximately day 4. A similar pattern of differentiation-dependent upregulation was observed for the gene encoding a lipogenic enzyme, i.e., malic enzyme (ME). In contrast to mixed glial cultures, however, this developmental gene upregulation was not significantly affected by severe hypoglycemia (approximately 0.02 mg/ml). The results indicate that the effect of glucose deprivation on oligodendrocyte genes observed in mixed glial cultures is mediated by other cells. The upregulation of the genes in differentiating oligodendrocytes was accompanied by the production of myelin-related membrane that was isolated by density gradient fractionation. In contrast to the effect on gene expression, this anabolic activity was highly dependent on glucose, as seen from a profound suppression by severe hypoglycemia.
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  • 83
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    European journal of plant pathology 105 (1999), S. 519-533 
    ISSN: 1573-8469
    Keywords: genome ; gene expression ; mollicute ; recombination ; transposition ; virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Spiroplasmas are members of the Class Mollicutes, wall-less prokaryotes having a high adenosine–thymidine content in their small genomes. Spiroplasma citri is a plant pathogen that inhabits phloem. Like other phytopathogenic spiroplasmas and the related phytoplasmas, it is transmitted from plant to plant by phloem-feeding leafhoppers that serve as alternate hosts for the spiroplasma as well as vectors. Genetic information in spiroplasmas is carried on a circular chromosome, on plasmids and/or in virus genomes. A picture emerging from recent research on the S. citri genome is one of frequent and often extensive variation, resulting from a number of different mechanisms. Expansion and contraction events must continually be occurring in about equal proportions so that the net genome size varies within defined boundaries. Particularly impressive are large changes in genome size that can occur in only a few generations. As with most organisms, genetic variation in S. citri results from variation in extrachromosomal DNA content, changes due to DNA replication and repair processes and changes due to recombination. The implied flux of genetic information into and out of the S. citri genome should be beneficial to the bacterium, allowing it, with its small genome size, to adapt to new environments.
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  • 84
    ISSN: 1573-4935
    Keywords: Mucin ; lung cancer ; gene expression ; secretion ; lung adenocarcinoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Mucins comprise an important class of tumor-associated antigens. The objectives of the present study were (a) to establish an in vitro model system using human non-small cell lung adenocarcinoma cell lines NCIH650 and NCIH2077 (b) provide evidence that these cell lines secrete mucin in culture conditions and (c) investigate the effects of select secretagogues on mucin secretion. The cell lines were established in ACL-4 medium containing several growth factors and retinoic acid and 5% fetal calf serum. The high molecular weight glycoconjugates secreted in the culture medium were purified by ammonium sulfate precipitation and Superose 6 and Superose 12 FPLC chromatography. The purified high molecular weight glycoconjugate fraction and the carcinoma cells were shown to have mucin by dot blot, Western blot and immunohistochemical analysis, respectively, using specific antibodies to purified major mucin, HTM-1. Also, incorporation experiments with mucin precursor 3H-glucosamine demonstrated that the cells indeed synthesize high molecular weight mucins. The effects of secretagogues such as, 8-bromocyclic AMP, ionomycin, phorbol-12-myristate-13-acetate and neutrophil elastase on mucin secretion were also investigated. Only 8-bromocyclic AMP and neutrophil elastase influenced mucin secretion. These studies provided strong evidence that the lung adenocarcinoma cell lines secrete high molecular weight mucins in culture conditions and only two of the four tested secretagogues significantly increased mucin secretion. Thus, this in vitro model system may be useful in determining alterations in mucin structure, if any, in lung adenocarcinomas as well as in studying the regulation of mucin gene expression.
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  • 85
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    Apoptosis 4 (1999), S. 255-261 
    ISSN: 1573-675X
    Keywords: Apoptosis ; cell cycle ; G2/M phase ; Fas ; Jurkat cell.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The relationship between the cell cycle and Fas-mediated apoptosis was investigated using Jurkat cells. Analysis of the inducibility of apoptosis by anti-Fas antibody during the cell cycle synchronized by the thymidine double-block method, showed that apoptosis was induced in only 50% of the G2/M phase cells, while most of cells in the other phases underwent apoptosis. These observations indicate that G2/M phase cells are more resistant to Fas-mediated apoptosis than cells in other phases. Furthermore, a detailed analysis of G2/M phase found that only 20–30% of the cells underwent apoptosis 12 h after the removal of the second thymidine block (pre-G2/M phase). This suggests that Fas-mediated apoptosis is potently suppressed during the pre-G2/M phase. A possible explanation for the observation that cells in the pre-G2/M phase are less sensitive to anti-Fas antibody is lower expression level of Fas. To test this possibility, Fas expression levels on the cell surface during the cell cycle were examined. The content of Fas on the cell surface, however, did not change appreciably during the cell cycle. Thus, the suppression of apoptosis in the pre-G2/M phase is determined downstream after the receipt of the apoptotic signal through Fas.
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  • 86
    ISSN: 1573-675X
    Keywords: Apoptosis ; B/T blood lymphocytes ; γ-glutamyltransferase ; glutathione ; glutathione S transferase ; membrane permeability ; type I (IDDM) ; type II (NIDDM) diabetes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have compared the concentrations of intracellular glutathione (GSH), glutathione-dependent antioxidative enzymes, the cell death rate and immunophenotype profile of peripheral blood mononuclear cells (PBMC) from healthy donors and from patients with insulin-dependent type I (IDDM) or non insulin-dependent type II (NIDDM) diabetes mellitus. The IDDM and NIDDM patients had above-normal absolute lymphocyte counts, whereas the percentages of CD3, CD4 and CD8 T lymphocytes were significantly reduced. In contrast, the absolute number and percentage of B lymphocytes was higher in diabetic patients than in healthy donors. The low intracellular reduced glutathione (GSH) and the unbalanced profile of key enzymes involved in GSH metabolism, gamma glutamyltransferase (γ-GT) and glutathione-S-transferase (GST), account for the increased oxidative status of PBMC from diabetic patients. The plasma membranes of PBMC from diabetic patients were less permeable to propidium iodide than those of PBMC from healthy donors, indicating that the apoptotic cell death rate was lower in the cells from diabetic patients. These differences are potentially useful markers of pathogenic metabolic changes which occur during clinical diabetes and if they are confirmed could be used to identify the onset of diabetes.
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  • 87
    ISSN: 1573-675X
    Keywords: Apoptosis ; fluorescence microscopy ; seminoma ; TdT.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Apoptosis morphology (DNA condensation) and internucleosomal DNA cleavage (TdT assay) were measured simultaneously on double fluorescence labeled testis tumor sections, employing conventional immunofluores cence microscopy. Six different apoptosis indices (AI) were determined based either solely on morphological or biochemical criteria, or on a combination of both processes. Measurements were performed in metastasized and non-metastasized seminoma, and in histological regions located distantly and associated with the tumor. Preliminary results on 19 histologies revealed that up to 66% of apoptotic cells were not detected, depending on the method used for apoptosis detection. Besides, no changes of solely morphologically defined AI was found in the different histological regions. By contrast, significant changes (p 〈 0.0004) in the different histological regions were detected when measuring AIs, e.g., defined by DNA fragmentation occuring without DNA condensation in apoptotic cells. Those changes were not detected in metastasized seminoma. These data, for the first time allow a comparison of two widely used approaches for apoptosis detection. Furthermore, the results reveal differences in apoptotic processes in tissue associated with non-metastasized seminoma detectable by a modified evaluated TdT assay but not by morphological changes, although this TdT method fails to show the total amount of apoptotic cells.
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  • 88
    ISSN: 1573-675X
    Keywords: Apoptosis ; bcl-2 ; Ca2+ ; flow cytometry ; hybridoma ; K+ ; Mg2+ ; necrosis.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have addressed the possibility that Ca2+, Mg2+ and K+ ions play a central role in governing the morphological and biochemical changes attributed to apoptotic cell death. By removing Ca2+, Mg2+ or K+ ions from the cell culture medium we were able to assess the contribution of each ion to hybridoma cell growth and viability. The differences were explained in terms of a possible reduction in their respective intracellular levels. From several lines of evidence, the deprivation of K+ ions was the most detrimental to cellular growth and viability and induced significant levels of early apoptotic cells. Another effect of this deprivation was to weaken the plasma membranes without causing membrane breakdown; exposure to high agitation rates confirmed fragility of the cell membranes. Removal of Mg2+ caused a reduction in the levels of early apoptotic cells and predisposed cells to high levels of primary necrotic death. The lower levels of apoptotic cells failed to demonstrate the classic nuclear morphology associated with apoptosis, while retaining other apoptotic features. These results highlighted the importance of utilizing several assays for the determination of apoptosis. The absence of Ca2+ appeared to be the mildest insult, but its deprivation did accelerate a significant decline in culture by increasing apoptotic death. Hybridoma cells overexpressing the apoptotic suppresser gene bcl-2 were protected from the predominantly necrosis inducing effects of Mg2+ ion deprivation and apoptosis inducing effects of Ca2+ ion deprivation. However, apoptosis was not as effectively suppressed in bcl-2 cells responding to incubation in K+ free medium. The inclusion of bcl-2 activity in the mechanisms of Ca2+ Mg2+ or K+ deprivation induced cell death emphasizes a close relationship between ionic dissipation and the apoptotic process.
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  • 89
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    Apoptosis 4 (1999), S. 365-372 
    ISSN: 1573-675X
    Keywords: Apoptosis ; chemoprevention ; colorectal cancer ; cyclooxygenase ; NSAIDs.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Epidemiological, clinical and animal studies indicate non-steroidal anti-inflammatory drugs (NSAIDs) to be chemopreventive for colorectal cancer. The best established target for NSAIDs are the two isoforms of cyclooxygenase (COX), a key enzyme in the biosynthesis of prostaglandins. Recent investigations using human colorectal tumor cell lines have focused on the cellular and molecular mechanisms potentially underlying the chemopreventive effect of NSAIDs. These studies have used ‘traditional’ NSAIDs and their metabolites which either do not inhibit COX, are non-selective for the COX isoforms or selectively inhibit COX-1 over COX-2, and recently developed NSAIDs that are highly selective for COX-2. In vitro, apoptosis is the dominant anti-proliferative effect of each of these classes of NSAID and sensitivity to NSAID-induced apoptosis increases with the malignant potential of the tumor cells. Limited in vivo evidence backs up these findings. Cell cycle arrest also contributes to the in vitro growth inhibitory effect of traditional NSAIDs. The induction of apoptosis by NSAIDs may result from the inhibition of the COX isoforms but other as yet undefined paths to NSAID-induced apoptosis clearly exist. A member of each class of NSAID is under trial as a chemopreventive agent for colorectal cancer.
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  • 90
    ISSN: 1573-675X
    Keywords: Apoptosis ; carcinogenesis ; colon cancer ; cyclooxygenase ; nonsteroidal anti-inflammatory drugs.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract NSAIDs are potent chemopreventive agents for colon cancer. Although their mechanism of action is unknown, it probably relates to their modulation of colon epithelial cell kinetics, i.e. apoptosis and/or cell proliferation. NSAIDs are pleiotropic in their biochemical activities; their best known effect is inhibition of prostaglandin H synthase (PHS), the enzyme catalyzing the biosynthesis of prostaglandins. Current data appear to lead to two conflicting conclusions. One body of data indicates that PHS is important in induction of apoptosis and colon carcinogenesis and that its inhibition by NSAIDs is required for induction of apoptosis and their overall chemopreventive effect. Another set of data indicates that NSAIDs may induce apoptosis and prevent colon cancer without inhibiting the activity of PHS. Both sides of this argument are presented and discussed. This apparent contradiction may be resolved if one accepts that both mechanisms are correct but that they act on different steps of this multistep process.
    Type of Medium: Electronic Resource
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  • 91
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    Apoptosis 4 (1999), S. 21-29 
    ISSN: 1573-675X
    Keywords: Apoptosis ; cell cycle ; E2F transcription factor ; nuclear phosphoprotein ; retinoblastoma ; transforming growth factor beta ; tumour suppressor gene.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The retinoblastoma gene and its protein product (Rb) have been studied intensively for their role in development, oncogenesis, cell growth, differentiation and cell cycle regulation. In addition, Rb appears to be a key factor in protecting cells from apoptosis. It is likely that Rb plays an essential role in cell survival by regulating the activity of multiple apoptotic mediators. Rb expression as a nuclear phosphoprotein is essential for normal cell cycle function. Clearly, any damage to the cell cycle or to DNA integrity is a potent trigger of apoptosis and Rb involvement. The E2F transcription factor is a critical component in the Rb-dependent apoptotic pathway(s), and can act either in concert or independently of the p53 tumour suppressor. Until recently, it was suggested that Rb, E2F and p53 modulate the apoptotic threshold by acting upstream of certain death proteases involved in programmed cell death. However, Rb activity can also be regulated downstream by the interleukin-converting enzyme-like (ICE-like) proteases, which abolish Rb activity by cleavage of aspartate-enriched regions within its C-terminus. Finally, Bcl-2, which inhibits multiple-factorial-induced apoptosis, does so, in part, by modulating the phosphorylation state of Rb. Taken together, Rb acts not only as a tumour suppressor protein which controls cell cycle function, but also determines the final destiny of a cell through apoptosis.
    Type of Medium: Electronic Resource
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  • 92
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    Apoptosis 4 (1999), S. 115-143 
    ISSN: 1573-675X
    Keywords: Apoptosis ; radiation therapy ; radiosensitivity ; tumor response.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Ionizing radiation is an effective means of killing tumor cells. Approximately 50% of all American cancer patients are treated with radiotherapy at some time during the course of their disease, making radiation one of the most widely used cytotoxic therapies. Currently, much effort is focused on understanding the molecular pathways that regulate tumor cell survival following radiotherapy, with the long term goal of developing novel therapeutic strategies for specifically sensitizing tumors to radiation. At present, there is particular interest in the role of tumor cell apoptotic potential as a regulator of both intrinsic and extrinsic determinants of the response of tumors to radiation therapy. Here we review what is currently known about the role of apoptosis as a mechanism of tumor cell killing by ionizing radiation and the relative contribution of apoptosis to cellular radiosensitivity and the ability to control human cancers using radiotherapy. The following topics will be discussed: (1) radiation-induced apoptosis in normal and malignant cells, (2) clinical findings with respect to apoptosis in human cancers treated with radiotherapy, (3) the contribution of apoptosis to intrinsic radiosensitivity in vitro, (4) the relevance of apoptosis to treatment outcome in experimental tumor models in vivo and (5) the potential of exploiting apoptosis as a means to improve the therapeutic efficacy of radiotherapy.
    Type of Medium: Electronic Resource
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  • 93
    ISSN: 1573-675X
    Keywords: Apoptosis ; β-IMAGER ; dengue virus ; DNA fragmentation ; radioimager μ-IMAGER ; rabie virus.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract DNA fragmentation is a key feature of the degradation phase of apoptosis. In this work we have developed an assay, based on radioimager (β-IMAGER and μ-IMAGER) quantification of radioactive nick end labelling (RANEL), which is quantitative, rapid and sensitive to study in vitro and in vivo induced apoptosis. To establish the technique, in vitro apoptosis of T cell lines was induced by stimulation of the Fas receptor; cells were labelled using TdT-mediated [α-33P] dCTP nick end labelling, after which then radioactivity was quantified using a β-IMAGER. We have also shown that the RANEL method can be applied to the quantification and visualisation, by μ-IMAGER analysis, of liver tissue sections from mouse Fas-induced fulminant hepatitis or from Dengue-1 virus infected individuals. Finally, this system has also been used to detect apoptosis induced by rabies virus in Jurkat T cells. These data have established a large field of application for the RANEL assay.
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  • 94
    ISSN: 1573-675X
    Keywords: Apoptosis ; cyclin D1 ; growth inhibition ; senescence.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract It is now apparent that apoptosis is closely linked to the control of cell cycle progression. During the G1 to S progression, cyclin D1, p53, and the cyclin dependent kinase inhibitors p21WAF1 and p27kip1 can play roles in induction of apoptosis. During the G2 and M phases, premature activation of Cdk1 can cause cells to enter mitotic catastrophe, which results in apoptosis. In this review we focus on factors acting during G1 and S, particularly cyclin D1, and their effects on cell growth, senescence and apoptosis. We emphasize that cyclin D1 can have diverse effects on cells depending on its level of expression, the specific cell type, the cell context and other factors. Possible mechanisms by which cyclin D1 exerts these diverse effects, via cyclin dependent kinase-dependent and -independent pathways, are discussed.
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  • 95
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    Apoptosis 4 (1999), S. 239-243 
    ISSN: 1573-675X
    Keywords: Apoptosis ; cell survival ; differentiation ; Drosophila ; EGFR ; hid ; ras.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The Drosophila epidermal growth factor receptor (EGFR), functioning through the Ras/Raf/MAPK pathway, promotes cell proliferation and differentiation. Recent work has demonstrated that EGFR functions via the same Ras/Raf/MAPK pathway to promote cell survival. This review summarizes the role of EGFR in differentiation and survival during Drosophila eye development.
    Type of Medium: Electronic Resource
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  • 96
    ISSN: 1573-675X
    Keywords: Apoptosis ; CD95 (Fas/APO-1) ; NF-κB/Rel ; T lymphocytes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The activity of NF-κB/Rel transcription factors can inhibit the apoptosis induced by TNF, UV or cancer therapy drugs in a number of cell types, including human T lymphocytes. Furthermore, the NF-κB/Rel inducer, phorbol-12-myristate-13-acetate (PMA), has been reported to suppress the CD95-induced apoptosis of human T lymphocytes. To verify whether the survival-enhancing effect of PMA required NF-κB/Rel activity, we generated two Jurkat cell sublines (AL.7 and AL.8) transfected with a pCMV4-IκBα construct, and two (AL.3 and AL.5) with the void pCMV4 vector. Compared to wild type, AL.3 and AL.5 cells, the AL.7 and AL.8 sublines displayed markedly lower amounts of NF-κB/Rel nuclear complexes and a reduced expression of a κB-controlled CAT reporter gene after 1 and 4 h of incubation with PMA, respectively. All the five cell types displayed negligible levels of apoptosis when cultured with medium or PMA alone; when stimulated with the mAb CH-11, the AL.7 and AL.8 sublines displayed apoptotic responses only slightly (〈0.5 fold) higher than control cells. On the other hand, the salvage activity of PMA was partially impaired in the AL.7 and AL.8 sublines. PMA inhibited apoptosis by 〉85% in wild type, AL.3 and AL.5 cells and by 〈60% in the AL.7 and AL.8 sublines; the apoptosis percentages in the mAb CH-11 + PMA cultures of the IκBα-transfected cells were 〉4-fold higher than in control cells. We conclude that the inhibition of the CD95-induced apoptosis by PMA relies on both NF-κB/Rel-dependent and -independent mechanisms. The partial contribution of these nuclear factors to the suppression of apoptosis indicates that the NF-κB/Rel activity can influence the extent of the CD95-induced T cell death.
    Type of Medium: Electronic Resource
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  • 97
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    Apoptosis 4 (1999), S. 5-10 
    ISSN: 1573-675X
    Keywords: Apoptosis ; atherosclerosis ; cytokines ; Fas ; p53 ; retinoblastoma.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Intimal cell death has been a recognized feature of advanced atherosclerotic disease. With the advent of DNA in situ end labelling and/or ultrastructural techniques, recent findings suggest that cells of an atheroma undergo programmed cell death or apoptosis. The pathophysiologic relevance of apoptosis in atherosclerotic disease is debatable. Apoptotic cell death may influence lesion progression and thus reduce overall plaque burden. Alternatively, apoptosis may prove a means of quenching the inflammation, converting cellular-rich lesions to so-called ‘stable’ fibrous hypocellular plaques or conversely weaken the fibrous cap causing plaque rupture, a major cause of acute coronary syndromes. Apoptotic cells within plaques are typically macrophages, smooth muscle cells and T-cells and the frequency of death varies in the different regions of the lesion. The precise signalling pathways of apoptosis in plaques are unknown. There is however, some evidence that production of immune cytokines may promote apoptosis through activation of the Fas ligand-mediated death pathway. Genetic signals that regulate apoptosis in the atheroma, at least in smooth muscle cells, may involve the tumour suppressor genes p105 RB and p53. Further studies as to the relevance of apoptosis in acute coronary syndromes and potential mechanisms are emerging.
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  • 98
    ISSN: 1573-675X
    Keywords: Apoptosis ; extrachromosomal c-myc genes ; hydroxyurea.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Hydroxyurea (HU) increases extrachromosomal DNA elimination in tumor cell lines. The c-myc oncogene is one of the many relevant amplified genes contained within the extrachromosomal DNA compartment. Spontaneous loss of amplified copies of c-myc induces terminal differentiation and apoptosis in the human HL-60 leukemia cell lines. In the present study, we evaluate HU's ability to induce apoptosis by eliminating extrachromosomally located c-myc oncogene in human tumor cell lines. The consequences of eliminating extrachromosomal DNA by HU were explored in two different cell lines using the TdT assay and acridine orange/ethidium bromide labeling. COLO 320 clone 3 and COLO 320 clone 21 cell lines contain the same number of amplified copies of c-myc oncogene, but located respectively on extrachromosomal DNA, and intrachromosomally in homogeneously staining regions. HU induced apoptosis in the COLO 320 clone 3 cell line by a time and concentration dependent mechanism but could not induce apoptosis in the COLO 320 clone 21 cell line. These results suggested that HU-induced apoptosis in COLO 320 cell lines depends on elimination of extrachromosomal amplified copies of the c-myc oncogene. The ability of HU to eliminate extrachromosomally amplified copies of the c-myc oncogene and to induce apoptosis should be considered when targeting malignancies with amplification of the c-myc oncogene in an extrachromosomal site.
    Type of Medium: Electronic Resource
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  • 99
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    Apoptosis 4 (1999), S. 383-388 
    ISSN: 1573-675X
    Keywords: Apoptosis ; cell cycle ; proliferation ; ras.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Cell population homeostasis is a balance between cell proliferation on one hand and the rate of cell loss on the other hand. Normal tissue homeostasis requires the physiological deletion of cells by activation of apoptosis, a genetically determined program of autonomous cell death. ras is most probably the most important oncogene in human cancer. It is mutated in 30% of all tumors especially those of the gastrointestinal tract. In regulating apoptosis ras has many faces. it has both negative and positive effects depending on the stimulation and cell type. The responses of cells to ras signaling depends on the level of Ras expression, the activity of various pathways, and which of the cell cycle check points are functioning. New farnesyl transferase inhibitors and non-steroidal anti-inflammatory compounds may provide a new strategy for novel therapeutic modalities in the treatment of human cancer. The first clinical trials have been initiated, preliminary results are promising, although no firm results are yet available.
    Type of Medium: Electronic Resource
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  • 100
    ISSN: 1573-675X
    Keywords: Apoptosis ; cell cycle synchronization ; HL60 ; hypusine ; K562 ; mimosine.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Mimosine, a plant amino acid not found in proteins, has been widely used as a synchronizing agent, blocking the progression of cell cycle on the G1/S phase border. The mechanism by which this block is achieved is still unclear. We report that in HL60 cells the synchronization is related to an increase in apoptosis. Another human tumor cell line, K562, is insensitive to both phenomena thereby demonstrating that apoptosis observed in HL60 is line-specific. We hypothesize that the mimosine-induced apoptosis and alteration of the cell cycle is due to the inhibition of hypusine generation.
    Type of Medium: Electronic Resource
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