A new apparatus design for high temperature (up to 950°C) quasi-elastic neutron scattering in a controlled gaseous environment

A design for a sample cell system suitable for high temperature Quasi-Elastic Neutron Scattering (QENS) experiments is presented. The apparatus was developed at the Spallation Neutron Source in Oak Ridge National Lab where it is currently in use. The design provides a special sample cell environment under controlled humid or dry gas flow over a wide range of temperature up to 950 °C. Using such a cell, chemical, dynamical, and physical changes can be studied in situ under various operating conditions. While the cell combined with portable automated gas environment system is especially useful for in situ studies of microscopic dynamics under operational conditions that are similar to those of solid oxide fuel cells, it can additionally be used to study a wide variety of materials, such as high temperature proton conductors. The cell can also be used in many different neutron experiments when a suitable sample holder material is selected. The sample cell system has recently been used to reveal fast dynamic processes in quasi-elastic neutron scattering experiments, which standard probes (such as electrochemical impedance spectroscopy) could not detect. In this work, we outline the design of the sample cell system and present results demonstrating its abilities in high temperature QENS experiments.

Neutron Laue diffraction study on the magnetic phase diagram of multiferroic MnWO4 under pulsed high magnetic fields

We have combined time-of-flight neutron Laue diffraction and pulsed high magnetic fields at the Spallation Neutron Source to study the phase diagram of the multiferroic material MnWO(4). The control of the field-pulse timing enabled an exploration of magnetic Bragg scattering through the time dependence of both the neutron wavelength and the pulsed magnetic field. This allowed us to observe several magnetic Bragg peaks in different field-induced phases of MnWO(4) with a single instrument configuration. These phases were not previously amenable to neutron diffraction studies due to the large fields involved.

Antitumor activity of recombinant adenoviral vectors expressing murine IFN-alpha in mice injected with metastatic IFN-resistant tumor cells

Recent studies have shown that gene therapy with type I interferon (IFN) in an adenovirus vector is a powerful tool to suppress the growth of human tumors transplanted in immune-deficient mice. However, in these studies the host immune-mediated effects, which may be important in mediating the long-term control of tumor growth by these cytokines, was not studied. In this paper, we evaluate the antitumor efficacy of different adenoviral vectors containing mouse IFN-alpha genes (i.e., a first-generation replication-defective vector containing IFN-alpha1 and two different second-generation vectors containing IFN-alpha2) in immunocompetent DBA/2 mice transplanted with highly metastatic Friend leukemic cells resistant in vitro to type I IFN. We found that injection of all the different adenovirus vectors containing mouse IFN-alpha( genes resulted in a marked antitumor response in mice transplanted either subcutaneously or intravenously with IFN-resistant Friend leukemic cells compared to tumor-bearing animals inoculated with a control vector. Tumor growth inhibition after injection of IFN-adenovirus vectors was associated with a prolonged presence of high IFN levels in the sera of the injected mice. Suppression of metastatic tumor growth was also observed after a single injection of the IFN--adenovirus recombinant vectors, whereas a comparable antitumor response generally required several injections of high doses of IFN. Altogether, these results demonstrate that IFN--adenoviral vectors can efficiently inhibit metastatic tumor growth by host-mediated mechanisms and suggest that adenovirus-mediated IFN-alpha gene therapy may represent an attractive alternative to the conventional clinical use of this cytokine, which generally requires multiple injections of high IFN doses for a prolonged period of time.

Type I consensus IFN (IFN-con1) gene transfer into KSHV/HHV-8-infected BCBL-1 cells causes inhibition of viral lytic cycle activation via induction of apoptosis and abrogates tumorigenicity in sCID mice

In this study, we investigated the effects of human type I consensus interferon (IFN-con1) (Amgen) gene transfer into body cavity-based lymphomas (BCBL)-1 cells, which are latently infected with Kaposi's sarcoma-associated herpesvirus (KSHV) human herpesvirus-8 (HHV-8). Both the basal and 12-O-tetradecanoyl phorbol-13-acetate (TPA)-stimulated production of KSHV/HHV-8 mature virions was strongly inhibited in genetically modified IFN-producing BCBL-1 cells as compared with parental or control transduced counterparts. A similar inhibition was obtained on treatment of parental BCBL-1 cells with exogenous IFN-con1. The reduction in KSHV/HHV-8 production was associated with a decrease in the basal and TPA-stimulated intracellular amount of the linear form of the viral genome. Interestingly, 25%40% of the IFN-producing BCBL-1 cell population underwent spontaneous apoptosis in vitro. TPA treatment, which did not significantly affect the viability of the parental and control BCBL-1 cells, resulted in the apoptotic death of up to 70% of the IFN-producing cell population. Addition of exogenous IFN-con1 to parental BCBL-1 cells produced similar effects, although less intense. Injection of either parental or control-transduced BCBL-1 cells into SCID mice resulted in progressively growing tumors characterized by an unusually high level of tumor angiogenesis. In contrast, complete tumor regression was observed in all the mice injected either subcutaneously (s.c.) or intraperitoneally (i.p.) with the IFN-producing BCBL-1 cells. These results represent the first evidence that type I IFN can counteract the activation of a productive herpesvirus infection in latently infected tumor cells by the induction of apoptosis, providing an interesting link between the antiviral and antitumor activities of this cytokine. These data suggest the possible advantages of strategies of type I IFN gene transfer (with respect to the use of the exogenous cytokine) for the treatment of patients with some HHV-8-induced malignancies.

Local and systemic antitumor response after combined therapy of mouse metastatic tumors with tumor cells expressing IFN-alpha and HSVtk: perspectives for the generation of cancer vaccines

In this study, we have evaluated the local versus systemic antitumor response in tumor-bearing mice subjected to a combined therapeutic regimen based on the injection of genetically modified Friend erythroleukemia cells (FLC) producing IFN-alpha and expressing the HSVtk (tk) gene, and we have investigated the host immune mechanisms involved in tumor rejection and development of antitumor immunity. Repeated subcutaneous (s.c.) injections of IFNtk-expressing tumor cells, followed by GCV administration, were effective in counteracting the growth of both contralateral parental tumors as well as visceral metastases, whereas similar treatments with control tk cells (i.e. nonproducing IFN) were ineffective. Morphologic analyses of the homolateral and contralateral tumor tissues and in vivo immunosuppression experiments with specific monoclonal antibodies revealed that both CD4+ and CD8+ T lymphocytes played essential roles in the generation of a definite antitumor response after the combined therapeutic regimen. We have also compared the effectiveness of irradiated versus viable tumor vaccines co-expressing the two genes in the FLC model and in the poorly immunogenic metastasizing TS/A adenocarcinoma tumor system. Repeated injections of high doses of irradiated IFN-alpha-tk-expressing tumor cells followed by GCV administration resulted in the cure of the majority of mice bearing established metastatic tumors, while repeated inoculations of the same number of viable tumor vaccines were much less effective. We conclude that; (1) IFN-alpha is an essential cofactor in the generation of a systemic antitumor immunity following the prodrug-induced tumor cell killing; (2) vaccines co-expressing an autotoxic gene and a cytokine gene may represent promising new tools for the treatment of some cancer patients.

Cure of mice with established metastatic friend leukemia cell tumors by a combined therapy with tumor cells expressing both interferon-alpha 1 and herpes simplex thymidine kinase followed by ganciclovir

Transduction of the murine interferon-alpha (IFN-alpha) gene into various malignant mouse tumor cells has resulted in the loss of tumorigenicity and an acquired capacity to induce long-lasting antitumor immunity following their injection into immunocompetent syngeneic mice. In the present study, we investigated the effectiveness of IFN-alpha-producing tumor cells in the therapy of mice with established mouse tumors. In DBA/2 mice bearing subcutaneous (s.c.) Friend erythroleukemia cell (FLC) tumors, we found that to achieve some antitumor response (i) it was necessary to inject high numbers of IFN-alpha-producing FLC, which occasionally lead to the formation of slowly growing tumors; and, that (ii) repeated injections of irradiated IFN-alpha-FLC did not result in any antitumor effect. The therapeutic potential of IFN-alpha-producing FLC rendered sensitive to ganciclovir (GCV), by transfer of the herpes simplex virus thymidine kinase (tk) gene, was investigated. Complete tumor rejection and cure was observed in > or = 70% of the animals after injection of high numbers (10(7)) of IFN-alpha-producing tk-expressing tumor cells followed 4 days later by repeated GCV treatments, whereas only a slight increase in survival time was obtained after administration of control tk-expressing tumor cells (not producing IFN) and GCV. Tumor rejection was associated with a dramatic destruction of tumor tissue and with the subsequent development of a potent and long-lasting antitumor immunity. No therapeutic effect was observed in immunosuppressed nude mice. These data indicate that this approach may represent an effective and safe therapeutic strategy for antitumor cytokine gene therapy.

Local and systemic response of mice to interferon-alpha 1-transfected Friend leukemia cells

DBA/2 mice were injected subcutaneously with an interferon (IFN)-alpha/beta-resistant line of Friend erythroleukemia cells (FLC) transfected with the mouse IFN-alpha 1 gene. These tumor cells produced IFN constitutively, and mice had persistently high levels of IFN in the circulation. We examined the IFN-induced host mechanisms responsible for the local inhibition of growth of these IFN-alpha-transfected FLC and some of the unusual systemic effects of constant interferonemia such as extramedullary hematopoiesis in the liver, an increase in myeloid cells in the spleen, and persistently elevated splenic natural killer (NK) cell activity. In addition, both DBA/2 +/bg and beige mice developed a rapid and specific resistance to intravenous challenge with parental FLC. In previous experiments DBA/2 beige mice could not be protected by exogenous IFN-alpha/beta. The differences in the response of mice to the constitutive production of IFN-alpha by IFN-alpha-transfected tumor cells and their response to exogenous IFN is discussed in terms of the effects of IFN on the host and of antitumor therapy.

Alpha 1-interferon gene transfer into metastatic Friend leukemia cells abrogated tumorigenicity in immunocompetent mice: antitumor therapy by means of interferon-producing cells

Highly metastatic alpha/beta-interferon (IFN-alpha/beta)-resistant Friend leukemia cells (FLC) were transfected with a retroviral vector (pLTneoL-5) containing the mouse IFN-alpha 1 gene. Transfected clones were isolated and tested for their capacity to secrete IFN-alpha 1 and their tumorigenicity when injected s.c. into immunocompetent syngeneic DBA/2 mice. Almost all FLC clones producing IFN in the range of 16-512 units/ml failed to grow when injected s.c. or i.p. into normal mice, whereas control FLC (transfected with a vector without the IFN gene) exhibited the highly malignant phenotype of the original FLC. High levels of IFN were detected in peritoneal fluid, tumor extracts, and sera of mice given injections of IFN-producing cells. Injection of mice with antibodies to IFN-alpha/beta resulted in the development of tumor ascites in mice transplanted i.p. with IFN-producing FLC. In contrast to the tumor rejection observed in immunocompetent mice, IFN-producing FLC were highly tumorigenic when transplanted into immunosuppressed nude mice. Mice given injections of IFN-producing FLC developed a long-lasting tumor-specific immune resistance to subsequent injection with highly metastatic FLC. Simultaneous s.c. injection of both metastatic FLC (approximately 10(3) 50% lethal doses) and IFN-producing cells resulted in potent inhibition of the tumor growth, with a survival rate of approximately 50% for injected mice. Contralateral injection (s.c.) of IFN-producing FLC into mice with established metastatic tumors produced a marked inhibition of tumor growth, with a survival rate of 10% for injected mice. These results indicate that: (a) the genetic modification of highly metastatic FLC by means of transfer of the IFN-alpha 1 gene results in potent tumor cell rejection, which is mediated by an IFN-induced host immune response; (b) injections of IFN-producing tumor cells are effective in inhibiting tumor growth in mice with established metastatic tumors. These data suggest that tumor cells transfected with the IFN-alpha gene might be used as an effective therapy for the treatment of certain human metastatic tumors, provided that suitable strategies are defined to prevent growth of the cytokine-producing cells.

Inhibition of Friend leukemia cell visceral metastases by a new monoclonal antibody and role of the immune system of the host in its action

We developed a syngeneic mouse IgG2a monoclonal antibody (MAb) A9D41 directed against the Friend leukemia virus envelope gp70 antigen present on the cell surface membranes of virus producer 3C18 Friend leukemia cells (FLC). A9D41 showed a marked antitumor activity in DBA/2 mice given injections of gp70 positive 3C18 FLC, but it was ineffective in mice given injections of gp70 negative 745 FLC or unrelated tumor cells. A9D41 was particularly effective in inhibiting the development of 3C18 FLC liver and spleen metastases. MAb was also effective as adjuvant therapy in inhibiting visceral metastases after excision of an established s.c. FLC tumor, and combined therapy of A9D41 with mouse interferon alpha/beta was more effective than MAb or interferon alpha/beta alone. The immune system of the host played a decisive role in the antimetastatic action of A9D41. Thus, although MAb was cytotoxic for 3C18 FLC in vitro in the presence of rabbit complement, the F(ab')2 fragment was ineffective in vivo, and the antitumor effect of MAb was abolished in mice treated with an antibody to CD4 and diminished in natural killer cell-deficient beige and athymic nude mice. MAb-treated mice surviving injection of FLC developed an immune response to 3C18 FLC.

The repair of DNA damage induced in V79 mammalian cells by the nitroimidazole-aziridine, RSU-1069. Implications for radiosensitization

The induction and repair of single (ssb) and double (dsb) strand breaks in DNA under aerobic or hypoxic conditions have been determined using sucrose sedimentation techniques following incubation of V79 mammalian cells with RSU-1069 or misonidazole, representative of a conventional 2-nitroimidazole radiosensitizer, for 1-1.5 hr at either 293 or 277 degrees K and subsequent irradiation at 277 degrees K. In all cases, the dose dependences for the induction of strand breaks are linear and consistent with an enhancement in the yield of DNA damage induced by the 2-nitroimidazoles under hypoxic conditions. With RSU-1069 at 293 degrees K, the dose dependence of ssb is displaced reflecting DNA damage induced during pre-incubation. From these dependences, it is evident that the enhanced radiosensitization by RSU-1069 may not be accounted for in terms of accumulation of the agent at DNA. From the repair studies, DNA breaks induced by RSU-1069 in the absence of radiation have been shown to persist for at least 3 hr. With a combination of RSU-1069 and radiation under hypoxic conditions, the repair timescale of the induced breaks is significantly longer and an increase in the residual yields of both ssb and dsb (at 2-3 hr) was observed when compared with the observation in the presence of misonidazole or oxygen. From these studies, it is inferred that the enhanced radiosensitization of RSU-1069 at 293 degrees K is a consequence of the formation of non-repairable DNA damage together with a modification of the repairability of the radiation-induced DNA breaks.