Induction of apoptosis in human leukemia K562 cells by alpha-anordrin

The apparent coexistence of primary biliary cirrhosis (PBC) and autoimmune hepatitis in the same patient raises unresolved problems for nosology and therapy. These are exemplified by a 45-year-old Japanese woman with overlapping clinical, serological and histological features of autoimmune cholangitis and autoimmune hepatitis. The classical serological test for PBC, antimitochondrial antibody (AMA) by immunofluorescence, was atypical. By immunoblotting there was reactivity with one of the enzymes of the 2-oxo-acid dehydrogenase complex (2-OADC) family, now recognized as autoantigens responsible for AMA reactivity. Also there was reactivity by immunofluorescence for antinuclear antibodies (ANA), one showing the typical speckled pattern of anti-Sp-100 and the other the peripheral pattern of antinuclear membrane antibody, both with titres > 10(6). There was also a positive result to the lupus erythematosus (LE) cell test. Treatment with ursodeoxycholic acid was beneficial. Thus while the clinical presentation suggested the overlapping syndrome of autoimmune hepatitis and PBC, PBC eventually proved to be the likely diagnosis. We suggest that apparent cases of overlapping PBC-autoimmune cholangitis-hepatitis syndromes, after detailed testing, will mostly align with PBC.     

Induction of apoptosis in human neuroblastoma cells by abrogation of integrin-mediated cell adhesion

The survival, proliferation and differentiation of neuroblastoma (NB) cells are largely dependent on adhesion to extracellular matrix (ECM) proteins. Integrin occupancy seems to play a primary role. To elucidate the role of integrin heterodimers during neuronal cell death, we have analysed the changes in integrin expression in 2 human NB cell lines which represent different stages of neuronal maturation. Retinoic acid (RA) had different effects on the 2 NB cell lines: on LAN-5 cells it acted as a differentiation-promoting agent, while it had an anti-proliferative effect on GI-LI-N cells, driving them to apoptosis. Indeed, this occurrence was evidenced by the visualization of a "DNA ladder" on gel electrophoresis, by propidium iodide staining, and by DNA flow cytofluorimetric analysis. RA treatment rapidly and drastically decreased integrin expression and cell adhesion on GI-LI-N cells. These findings were also obtained by treating both NB cell lines with the apoptotic agent fenretinide. Furthermore, treatment of NB cells with anti-sense oligonucleotides to beta 1 integrin chain specifically induced chromatin condensation and nucleosomal DNA laddering. Moreover, blocking cell-matrix interactions by means of perturbing antibody against beta 1 subunit resulted in the induction of typical features of apoptotic cells. In conclusion, these findings indicate that abrogation of cell adhesion through down-modulation of integrin receptors plays a crucial role in the induction of neuroblastoma programmed cell death.     

Induction of apoptosis in human dermal microvascular endothelial cells and infantile hemangiomas by interferon-alpha

Post-transfusion graft-versus-host disease (PT-GVHD) is a fatal adverse effect of blood transfusion. In spite of its severity, there is no effective treatment at present for PT-GVHD. Previously, we reported that chloroquine (CH) inhibited the cytotoxicity of cytotoxic T-cell (CTL) clones and tumour necrosis factor beta (TNF beta) production by TNF beta-producing clones in vitro, both the clones being derived from peripheral blood lymphocytes (PBMCs) of PT-GVHD patients. To explore the possibility of utilizing CH for the treatment of PT-GVHD, we extended our investigation of the immunosuppressive effects of CH in vitro to PBMCs derived from healthy donors. Our results show that CH inhibits the mixed lymphocyte reaction (MLR) between allogeneic PBMCs, production of inflammatory cytokines such as TNF alpha, interleukin-1 beta (IL-1 beta) and interferon gamma (IFN gamma) in mixed lymphocyte culture and natural killer cell activity, and, further, reduces the number of alloreactive CTL precursors.     

Induction of apoptosis in human pancreatic carcinoma cells by a synthetic bleomycin-like ligand

The increased polylactosamine glycosylation of LAMP-2 in MDCK cells cultured for 1 day relative to cells cultured for 3 days has been correlated with its slower rate of Golgi transit (Nabi and Rodriguez-Boulan, 1993, Mol. Biol. Cell., 4, 627-635). To determine if the differential polylactosamine glycosylation of LAMP-2 is a consequence of glycosyltransferase expression levels, the activities of beta1-6GlcNAc-TV, beta1-3GlcNAc-T(i), beta1-2GlcNAc-TI, beta1, 4Gal-T, alpha2-6sialyl-T, and alpha2-3sialyl-T were assayed and no significant differences in the activities of these enzymes in 1 and 3 day cell extracts were detected. During MDCK epithelial polarization, the Golgi apparatus undergoes morphological changes and apiconuclear Golgi networks were more evident in 3 day cells. Treatment with nocodazole disrupted Golgi networks and generated numerous Golgi clusters in both 1 day and 3 day cells. In the presence of nocodazole the differential migration of LAMP-2 in 1 and 3 day MDCK cells was maintained and could be eliminated by treatment with endo-beta-galactosidase, indicating that gross Golgi morphology did not influence the extent of LAMP-2 polylactosamine glycosylation. Nocodazole treatment did, however, result in the faster migration of LAMP-2 which was not due to modification of core N-glycans as the precursor form of the glycoprotein migrated with an identical molecular size. Following incubation at 20 degrees C, which prevents the exit of proteins from the trans-Golgi network, the molecular size of LAMP-2 increased to a similar extent in both 1 and 3 day MDCK cells. Extending the time of incubation at 20 degrees C did not influence the size of LAMP-2, demonstrating that its glycosylation is modified not by its retention within the Golgi but rather by its equivalent slower Golgi passage at the lower temperature in both 1 and 3 day cells. An identical effect was observed in nocodazole treated cells, demonstrating that Golgi residence time determines the extent of LAMP-2 polylactosamine glycosylation, even in isolated Golgi clusters.     

Azidothymidine resistance of H9 human T-cell lymphoma cells is associated with decreased sensitivity to antitumor agents and inhibition of apoptosis

Biology of HIV-1 associated neoplasias is modulated by viral and host factors. In addition the development of tumors and their response to therapy may be further influenced by long-term treatment of HIV-1 patients with nucleoside analogs such as AZT (3'-azido-3'deoxythymidine), ddI (2',3'-dideoxyinosine), ddC (2',3'-dideoxycytidine), d4T (2',3'-didehydro-2'3'-dideoxythymidine), and 3TC [(-)-beta-L-2',3'-dideoxy-3'-thiacytidine] alone or in combination. As these compounds can trigger mechanisms involved in chemoresistance, we tested whether prolonged in vitro treatment of H9 cells (T-cell lymphoma) with AZT alters sensitivity of lymphoma cells to antitumor agents used for AIDS-associated malignancies. H9 cells grown for more than two years in medium containing 250 microM AZT developed resistance to the toxic effects of AZT while retaining sensitivity for other nucleoside analogs including ddC or cytosine arabinoside (ARA-C). These cells designated H9rAZT250 were 2 to 10-fold less sensitive to the toxic effects of antitumor agents, including cisplatin (CDDP), vincristine (VCR), doxorubicin (DOX) and etoposide (VP-16), when compared with parental H9 cells. The resistance of H9rAZT250 cells to antitumor agents was associated with inhibition of apoptosis as demonstrated by ultrastructural investigations and DNA-fragmentation assay (ELISA). The expression of the antiapoptotic gene bcl-2 was increased in H9rAZT250 cells while expression of other genes involved in the regulation of apoptosis such as c-myc, p53 and Fas was not changed. These results demonstrate that prolonged in vitro treatment of H9 lymphoma cells with AZT results in the development of resistance to antitumor agents in association with inhibition of apoptosis and increased expression of bcl-2. Therefore AZT long-term treatment of some HIV-1 patients with malignancies may have affected behavior of tumor cells including response to therapy.     

Induction of tumor necrosis factor alpha in human neuronal cells by extracellular human T-cell lymphotropic virus type 1 Tax

To examine the role of human T-lymphotropic virus type 1 (HTLV-1) Tax1 in the development of neurological disease, we studied the effects of extracellular Tax1 on gene expression in NT2-N cells, postmitotic cells that share morphologic, phenotypic, and functional features with mature human primary neurons. Treatment with soluble HTLV-1 Tax1 resulted in the induction of tumor necrosis factor alpha (TNF-alpha) gene expression, as detected by reverse-transcribed PCR and by enzyme-linked immunosorbent assay. TNF-alpha induction was completely blocked by clearance with anti-Tax1 monoclonal antibodies. Furthermore, cells treated with either a mock bacterial extract or with lipopolysaccharide produced no detectable TNF-alpha. Synthesis of TNF-alpha in response to soluble Tax1 occurred in a dose-dependent fashion between 0.25 and 75 nM and peaked within 6 h of treatment. Interestingly, culturing NT2-N cells in the presence of soluble Tax1 for as little as 5 min was sufficient to result in TNF-alpha production, indicating that the induction of TNF-alpha in NT2-N does not require Tax1 to be continually present in the culture medium. Treatment of the undifferentiated parental embryonal carcinoma cell line NT2 with soluble Tax1 did not result in TNF-alpha synthesis, suggesting that differentiation-dependent, neuron-specific factors may be required. These results provide the first experimental evidence that neuronal cells are sensitive to HTLV-1 Tax1 as an extracellular cytokine, with a potential role in the pathology of HTLV-1-associated/tropical spastic paraparesis.     

Induction of T-cell hyporesponsiveness by intrahepatic modulation of donor antigen-presenting cells

In this study, we examined the ability of varying populations of donor cells from B6 mice to induce hyporesponsiveness in T lymphocytes from C3H mice in vitro and in vivo. Small, resting B lymphocytes were inefficient stimulators of T-lymphocyte proliferation compared to splenic mononuclear cells (SMNC) and lipopolysaccharide (LPS)-induced B-cell blasts in vitro (P < 0.05). Pretreatment of SMNC with anti-B7-1 or anti-intracellular adhesion molecule-1 (ICAM-1) monoclonal antibodies (mAb) similarly resulted in inefficient stimulation of T-cell proliferation in vitro (P < 0.05). However, in vivo, only intrahepatic, but not intravenous, injection of donor cells into C3H mice resulted in decreased T-lymphocyte proliferation in response to restimulation by alloantigen. This effect was most pronounced following intrahepatic injection of resting B lymphocytes or SMNC pretreated with anti-ICAM-1 mAb compared to uninjected or intravenously injected mice (P < 0.05). The hyporesponsiveness was associated with an increased production of interleukin-4 (IL-4) by the responder T lymphocytes and correlated with enhanced skin allograft survival. These data demonstrate that intrahepatic injection of donor-derived cells induces T-lymphocyte hyporesponsiveness. The mechanism appears to be modulated by an ICAM-1-mediated signal resulting in expansion of an IL-4-producing T-lymphocyte population.     

Overexpression of bcl-2 or bcl-XL fails to inhibit apoptosis mediated by a novel retinoid

Overexpression of bcl-2 or bcl-XL has been found to inhibit the induction of apoptosis in malignant cells by a large number of agents including a wide variety of chemotherapeutic drugs. CD437 ?6-[3-(1-adamantyl)-4 hydroxyphenyl]-2-naphthalene carboxylic acid? is a novel retinoid that induces apoptosis in a number of malignant cells through a unique mechanism of action. The addition of 1 microM CD437 to HL-60/NEO cells resulted in capase 3 (CPP32) activation and poly(ADP-ribose) polymerase (PARP) cleavage in 3 h whereas in bcl-2- or bcl-XL-overexpressing HL-60 cells CD437 induced CPP32 activation and PARP cleavage in 6 h. Although 50 and 300 nM CD437 were required to induce PARP cleavage in HL-60/NEO and HL-60/bcl-2, HL-60/bcl-XL cells, respectively, maximal apoptosis in both cell lines was achieved utilizing 300 nM CD437. All three cell lines, however, share identical dose-response curves in terms of their growth inhibition, suggesting that CD437-mediated inhibition of growth and induction of apoptosis represent two distinct and separable processes. In addition, CD437 induces GI arrest as well as p21WAFI/CIPI mRNA expression in these cells despite the overexpression of bcl-2 or bcl-XL. CD437 induced mitochondrial instability as indicated by cytochrome c leakage into the cytoplasm in all three cell lines. CD437 also induced growth inhibition and apoptosis of an apoptosis-resistant variant of the HL-60 cell line (HCW-2), which switched expression from bcl-2 to bcl-XL. CD437-mediated apoptosis is not accompanied by downregulation of bcl-2 or bcl-XL or upregulation of bax. The reason for the inability of bcl-2 or bcl-XL overexpression to inhibit CD437-mediated apoptosis is unclear. The ability of CD437 to initiate apoptosis in a spectrum of malignant cells without interference from bcl-2 or bcl-XL overexpression suggests that CD437 may possess significant therapeutic potential in the treatment of malignancy.     

Induction of apoptosis by benzene metabolites in HL60 and CD34+ human bone marrow progenitor cells

Two cell types, HL60 human promyelocytic leukemia cells and CD34+ human bone marrow progenitor cells, were used as model systems to explore a possible role for apoptosis in the myelotoxicity of the phenolic metabolites of benzene. HL60 cells were treated with either phenol, catechol, hydroquinone, or 1,2,4-benzenetriol and then stained with Hoechst 33342 and propidium iodide and subjected to fluorescent microscopy. Cells with nuclear condensation and fragmentation were scored as apoptotic, and etoposide (40 microM) was used as a positive control. Catechol, 1,2,4-benzenetriol, and hydroquinone induced marked time- (0-24 hr) and concentration- (25-100 microM) dependent apoptosis, whereas phenol (750 microM) did not. Under these conditions, no significant necrosis was observed. The induction of apoptosis was confirmed by internucleosomal cleavage of DNA, assessed by agarose gel electrophoresis. CD34+ cells treated with etoposide (40 microM) or hydroquinone (50 microM) for 18 hr were stained and subjected to fluorescent microscopy as above. The percentage of cells exhibiting nuclear condensation and/or fragmentation as well as high intensity staining significantly increased in both cases. The induction of apoptosis was confirmed using a terminal deoxynucleotidyl transferase assay. These data show that apoptosis can be induced in both HL60 and CD34+ human bone marrow progenitor cells by benzene metabolites. The ability of phenolic metabolites of benzene to induce apoptosis in human bone marrow progenitor cells may contribute to benzene myelotoxicity.     

Induction of apoptosis in human cancer cell lines by the novel anthracenyl-amino acid topoisomerase I inhibitor NU/ICRF 505

A 77-year-old woman with a productive cough and fever was admitted to the hospital. Pulmonary and endobronchial tuberculosis, pneumonia of the left upper lobe, and stenosis of the left main bronchus were diagnosed. She was given the antimycobacterial drugs isoniazid, rifampin, and streptomycin, and her condition improved. Two months later, bronchoscopy revealed semilunar-shaped stenosis of the left main bronchus, and auscultation revealed wheezing in the middle-end expiratory phase. A continuous flow murmur (Levine III) was also heard at the left anterior chest wall. Cardiac catheterization with subclavian arteriography revealed two left subclavian-pulmonary shunts. In a case of systemic-pulmonary shunt such as this, the bronchial stenosis could be surgically repaired, but the result would be an increase in dead space. If left untreated, the pulmonary hypertension would progress and symptoms of pulmonary disease would become more severe. Subclavian-pulmonary artery shunt is a very rare complication of pulmonary tuberculosis. Surgical treatment should consist of open bronchoplasty along with lobectomy and removal of the shunt, rather than embolization of the shunt and endoscopic bronchoplasty.     

Calcium induces phospholipid redistribution and microvesicle release in human erythrocyte membranes by independent pathways

The increase in intracellular Ca2+ concentration in erythrocytes and platelets results in simultaneous phospholipid scrambling and microvesicle shedding. Microvesicle formation involves membrane fusion events which were proposed either to be tightly linked to phospholipid transversal redistribution or to occur by a separate mechanism. We report here that in erythrocytes incubated in high K+ medium, or in resealed ghosts, phospholipid scrambling can be fully induced by intracellular Ca2+ without microvesicle formation. Furthermore, in ghosts resealed in the presence of spermine, intracellular Ca2+, at low concentration, was able to induce microvesicles, whereas scrambling was drastically inhibited. Surprisingly, in spermine-containing ghosts prepared from erythrocytes of a patient with a bleeding disorder, due to a lack of Ca2+-induced phospholipid scrambling and vesicle shedding (characterized as a Scott syndrome), Ca2+ also promoted microvesicle release. Data show that phospholipid scrambling and microvesicle production, although closely regulated, proceed by independent pathways.     

Adult T-cell leukemia/lymphoma on a background of clonally expanding human T-cell leukemia virus type-1-positive cells

Tumorous and nontumorous samples from patients with various forms of adult T-cell leukemia/lymphoma (ATLL) were analyzed using the sensitive inverse polymerase chain reaction (PCR) technique. In all samples, oligoclonal expansion of human T-cell leukemia virus (HTLV)-1 bearing T cells were detected, even for the tumorous samples that were mainly monoclonal by Southern blotting. For one case of smouldering ATLL, chemotherapy apparently reduced the number of detectable clones. Taken together with similar data on asymptomatic and symptomatic HTLV-1 carriers without malignancy, it would appear that ATLL appears on a prior background of HTLV-1-initiated oligoclonal expansion.     

Induction of Bax-alpha precedes apoptosis in a human B lymphoma cell line: potential role of the bcl-2 gene family in surface IgM-mediated apoptosis

The members of the bcl-2 gene family are major regulators of programmed cell death, but their role in sIg-triggered apoptosis remains unclear. Using sensitive and resistant variants of the human B cell line BL-41, we studied the expression of the bcl-2 gene family during surface IgM-mediated apoptosis. We found constitutive Bcl-2 and Bcl-x expression, which remained unaltered after sIg cross-linking, in both resistant and sensitive cells. This and other experiments suggest that constitutive expression of Bcl-2 or Bcl-x alone is not sufficient to protect from activation-induced cell death in B cells. We therefore investigated Bax-alpha, the death-promoting splice variant of Bax, and found strong induction of both mRNA and protein upon sIg stimulation in sensitive cells. However, resistant subclones showed only weak expression, which was not inducible by sIg cross-linking. We provide evidence that up-regulation of Bax-alpha and the resulting imbalance of Bcl-2/Bax might be a major regulator of sIg-mediated apoptosis. Additionally, we found strong constitutive expression of Bcl-xs, the death promoting variant of Bcl-x, in sensitive cells, whereas resistant cells showed only weak Bcl-xs expression. Thus, we observed a much stronger expression of the death-promoting proteins Bax-alpha (inducible) and Bcl-xs (constitutive) in sensitive cells than in resistant cells. We therefore propose a potential role of the novel bcl-2 gene family members bcl-x and bax in surface IgM-triggered apoptosis.     

Induction of apoptosis and potentiation of TNF- and Fas-mediated apoptosis in U937 cells by the xanthogenate compound D609

The purpose of Study 1 was to examine the effect of dietary soy on the progression of MDA-MB-435 human breast cancer cell solid tumors in nude mice. When toasted soy chips were fed at levels of 5%, 10%, or 20% (wt/wt) in a high-fat, linoleic acid-rich diet for 12 weeks, there was a trend for larger mammary fat pad tumors to occur with increasing soy intake. However, compared with the controls the severity of macroscopic lung metastasis was reduced significantly in the groups fed 10% and 20% soy. Study 2 compared the effects of diets containing 23% corn oil (CO), 18% menhaden oil (MO) + 5% CO, 18% MO + 5% CO + 10% soy chips, and MO or soy-supplemented diets + indomethacin treatment in the same animal model. Feeding the 18% MO diet without soy or indomethacin reduced primary tumor growth; statistically significant effects were not observed in any of the other groups. All three of the groups with MO supplementation showed a reduction in the occurrence and severity of macroscopic lung metastases, together with the expected decreases in tumor prostaglandin E levels. These effects were most pronounced when MO was combined with indomethacin treatment. When indomethacin was given with dietary soy, the previously reported suppressive effect of the cyclooxygenase inhibitor on MDA-MB-435 cell tumor progression was lost, despite reductions in tumor prostaglandin E concentrations.     

Induction of apoptosis in HL-60 human promyelocytic leukemia cells by adenosine A(3) receptor agonists

The effects of adenosine (ADO) analogs on cells of the human promyelocytic HL-60 line were examined. ADO A(3) receptor agonists, N(6)-(3-iodobenzyl)adenosine-5'-N-methylcarboxamide (IB-MECA, 30-60 microM) and 2-chloro-N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide (CI-IB-MECA, 10-30 microM) induced apoptotic cell death. In contrast, neither an A(1)/A(2) antagonist (XAC) nor other selective ADO receptor agonists (CPA, NECA and CGS21680) induced apoptosis at concentrations of <30 microM. Both IB-MECA and CI-IB-MECA significantly induced Ca(2+) release from intracellular Ca(2+) pools followed by Ca(2+) influx, suggesting the presence of phospholipase C-coupled ADO A(3) receptors on HL-60 cells. This was further supported by the presence of mRNA of ADO A3 receptor in the cells. These results suggest that activation of ADO A(3) receptors is responsible for the ADO-induced apoptosis in HL-60 cells and could be of potential therapeutic value in the treatment of leukemia.     

Induction of apoptosis by synthetic ceramide analogues in the human keratinocyte cell line HaCaT

In many laboratories, culturing skin melanocytes has become a routine research activity. However, recent investigations have revealed that the quality and quantity of the pigment formed in the cultured cells may differ significantly from those of the original skin pigment cells. To shed more light on this issue, we examined the influence of different culture media on pigment production. We showed that there were notable passage-to-passage variations in the synthesis of melanin. This was particularly true for phaeomelanin. It is therefore advisable to analyse the melanin in the cells before the start of experiments. In spite of the variations, basic differences in the pigmentation pattern between melanocytes isolated from light-skinned and dark-skinned individuals remained preserved in the corresponding cultures as observed by electron microscopy. Also, the total melanin content was higher in a skin type VI melanocyte culture than in skin type I and II melanocyte cultures. In contrast to total melanin, the phaeomelanin concentration of skin type VI cells was similar to that of the skin type I melanocytes. With higher L-tyrosine concentrations in the medium, as well as increased eumelanin synthesis, phaeomelanogenesis was also stimulated in all cultures tested. This stimulation was particularly prominent in skin type I melanocytes. Our preliminary experiments also showed that a melanocyte culture from atypical naevus cells exhibited a similar preference for phaeomelanogenesis when pigmentation was stimulated.     

Induction and detection of apoptosis in human periphery blood T-cells

Freshly isolated, human peripheral blood T (PBT) cells are resistant to induction of apoptosis. In this study, however, we have shown that although small numbers of monocytes (Mo) are required for PBT cells to proliferate optimally in response to mitogenic challenge, a relatively higher percentage of Mo results in a significant decrease in PHA-, but not ConA-induced T-cell proliferation. Interestingly, the decrease in T-cell proliferation correlated to an increase in apoptotic cell death. Moreover, ConA-induced PBT-cells underwent apoptosis in the presence of PHA-pretreated Mo, suggesting a key role of monocyte activation in this system. This apoptosis-promoting effect of activated Mo appeared to depend on contact or close proximity between Mo and PBT-cells, rather than via soluble mediators. Despite an increase in apoptosis by the presence of high numbers of Mo, PHA-stimulated PBT-cells released IL-2 at elevated levels proportional to the increasing numbers of Mo in cultures. They also expressed activation marker CD69 and the IL-2R-gamma chain on the cell surface at comparable or higher levels in the presence of high versus low numbers of Mo. These data suggest that PBT-cells can embark on a normal early phase of activation prior to undergoing apoptosis, thereby providing a model system to study how T-cells are committed to either proliferation or activation-induced apoptosis.     

Induction of specific T-cell tolerance by adenovirus-transfected, Fas ligand-producing antigen presenting cells

A major problem associated with adenovirus gene therapy is the T cell-mediated immune response, which is elicited by inoculation of the adenovirus vector and leads to rapid clearance of the virus and loss of transgene expression. In this study, the immune response to adenovirus was prevented by induction of specific T-cell tolerance by pretreatment with adenovirus-infected antigen-presenting cells (APC) that express Fas ligand. Compared with control-treated mice, the tolerized mice showed prolonged expression of lacZ upon administration of AdCMVlacZ 1 week after tolerance induction. In contrast to the control mice, the tolerized mice did not display proliferation of CD3+ T cells in the spleen in response to AdCMVlacZ. Tolerance induction also was indicated by the lower production of interferon-gamma and interleukin-2 by peripheral T cells isolated from AdCMVlacZ-challenged tolerized mice than by AdCMVlacZ-challenged control-treated mice. The T-cell tolerance was specific for the adenovirus as the T-cell responses to irrelative murine cytomegalovirus remained unimpaired. Our results indicate that adenovirus-specific T-cell tolerance can be induced by APCs that coexpress Fas ligand and adenovirus antigens. We propose that this new strategy can be used to induce tolerance to adenovirus vector gene therapy with resultant prolonged expression of the transgene.     

Leukemia inhibitory factor induces apoptosis and proliferation of human carcinoma cells through different oncogene pathways

The aim of this study was to investigate the effects of a high ambient pressure of He on vascular contraction induced by noradrenaline and to distinguish the effects of ambient pressure per se from those of increased pressure of inert gas. Rings of thoracic aorta were isolated from male Wistar rats. Isometric tension was measured in preparations exposed to 7.1 MPa (absolute pressure) of He. Dose-response curves for noradrenaline and contractions elicited by 120 mM KCl were compared with time-matched experiments performed at atmospheric pressure. The same protocol was also carried out under 7.1 MPa of N2. At the high pressure of He, the contraction elicited by noradrenaline was increased with no change in the response to K(+)-evoked depolarization. The tension developed in response to noradrenaline also increased under 7.1 MPa of N2 but the effects were less marked than during the He experiments. Moreover, the response to KCl was reduced in this circumstance. Hyperbaric conditions enhance the noradrenaline-induced contraction of rat aorta in vitro. This effect probably results from an action of pressure per se on activation of adrenoceptors. However, the hyperbaric-induced increase in vascular smooth muscle contraction is partially counteracted by high pressures of inert gases (N2, but also probably He), which impair the efficiency of the contractile machinery.