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Peripheral blood T cells transduced with a tumor-specific T-cell receptor (TCR) face problems of auto-reactivity and lack of efficacy caused by cross-pairing of exogenous and endogenous TCR chains, as well as short term in vivo survival due to activation and growth factor-induced differentiation. We here studied an alternative strategy for the efficient generation of naive CD8+ T cells with a single TCR. TCR-transduced human postnatal thymus-derived and adult mobilized blood-derived hematopoietic progenitor cells (HPCs) were differentiated to CD4+CD8+ double-positive T cells using OP9-Delta-like 1 (OP9-DL1) cultures. Addition of the agonist peptide induced double positive cells to cross-present the peptide, leading, in the absence of co-stimulation, to cell cycle arrest and differentiation into mature CD8+ T cells. Comprehensive phenotypic, molecular and functional analysis revealed the generation of naive and resting CD8+ T cells through a process similar to thymic positive selection. These mature T cells show a near complete inhibition of endogenous TCRA and TCRB rearrangements and express high levels of the introduced multimer-reactive TCR. Upon activation, specific cytokine production and efficient killing of tumor cells were induced. Using this strategy, large numbers of high-avidity tumor-specific naive T cells can be generated from readily available HPCs without TCR chain cross-pairing. [ABSTRACT FROM AUTHOR]

Peripheral blood T cells transduced with a tumor-specific T-cell receptor (TCR) face problems of auto-reactivity and lack of efficacy caused by cross-pairing of exogenous and endogenous TCR chains, as well as short term in vivo survival due to activation and growth factor-induced differentiation. We here studied an alternative strategy for the efficient generation of naive CD8(+) T cells with a single TCR. TCR-transduced human postnatal thymus-derived and adult mobilized blood-derived hematopoietic progenitor cells (HPCs) were differentiated to CD4(+)CD8(+) double-positive T cells using OP9-Delta-like 1 (OP9-DL1) cultures. Addition of the agonist peptide induced double positive cells to cross-present the peptide, leading, in the absence of co-stimulation, to cell cycle arrest and differentiation into mature CD8(+) T cells. Comprehensive phenotypic, molecular and functional analysis revealed the generation of naive and resting CD8(+) T cells through a process similar to thymic positive selection. These mature T cells show a near complete inhibition of endogenous TCRA and TCRB rearrangements and express high levels of the introduced multimer-reactive TCR. Upon activation, specific cytokine production and efficient killing of tumor cells were induced. Using this strategy, large numbers of high-avidity tumor-specific naive T cells can be generated from readily available HPCs without TCR chain cross-pairing. [ABSTRACT FROM AUTHOR]

In wild-type mice, T-cell receptor (TCR) γδ+ cells differentiate along a CD4 CD8 double-negative (DN) pathway whereas TCRαβ+ cells differentiate along the double-positive (DP) pathway. In the human postnatal thymus (PNT), DN, DP and single-positive (SP) TCRγδ+ populations are present. Here, the precursor-progeny relationship of the various PNT TCRγδ+ populations was studied and the role of the DP TCRγδ+ population during T-cell differentiation was elucidated. We demonstrate that human TCRγδ+ cells differentiate along two pathways downstream from an immature CD1+ DN TCRγδ+ precursor: a Notch-independent DN pathway generating mature DN and CD8αα SP TCRγδ+ cells, and a Notch-dependent, highly proliferative DP pathway generating immature CD4 SP and subsequently DP TCRγδ+ populations. DP TCRγδ+ cells are actively rearranging the TCRα locus, and differentiate to TCR− DP cells, to CD8αβ SP TCRγδ+ cells and to TCRαβ+ cells. Finally, we show that the γδ subset of T-cell acute lymphoblastic leukemias (T-ALL) consists mainly of CD4 SP or DP phenotypes carrying significantly more activating Notch mutations than DN T-ALL. The latter suggests that activating Notch mutations in TCRγδ+ thymocytes induce proliferation and differentiation along the DP pathway in vivo. [ABSTRACT FROM AUTHOR]

Human T lymphocytes can be generated from CD34 progenitor cells from different sources. This can be obtained in an in vivo model wherein human thymic tissue and fetal liver is transplanted in an immunodeficient mouse. However, human T cells are also generated in immunodeficient mice without co-transplantation of human thymus or in in vitro hybrid human–mouse fetal thymus organ culture. This shows that xenogeneic mouse thymus tissue supports human T cell differentiation. Finally, human T cells are generated on co-culture with murine stromal cells that express the Delta-like1 ligand for the Notch receptor. How these different environments influence the human T cell repertoire is reviewed and discussed. [ABSTRACT FROM AUTHOR]

Hematopoietic stem cells in the bone marrow (BM) give rise to all blood cells. According to the classic model of hematopoiesis, the differentiation paths leading to the myeloid and lymphoid lineages segregate early. A candidate ‘common lymphoid progenitor’ (CLP) has been isolated from CD34+CD38− human cord blood cells based on CD7 expression. Here, we confirm the B- and NK-differentiation potential of CD34+CD38−CD7+ cells and show in addition that this population has strong capacity to differentiate into T cells. As CD34+CD38−CD7+ cells are virtually devoid of myeloid differentiation potential, these cells represent true CLPs. To unravel the molecular mechanisms underlying lymphoid commitment, we performed genome-wide gene expression profiling on sorted CD34+CD38−CD7+ and CD34+CD38−CD7− cells. Interestingly, lymphoid-affiliated genes were mainly upregulated in the CD7+ population, while myeloid-specific genes were downregulated. This supports the hypothesis that lineage commitment is accompanied by the shutdown of inappropriate gene expression and the upregulation of lineage-specific genes. In addition, we identified several highly expressed genes that have not been described in hematopoiesis before.Leukemia (2007) 21, 311–319. doi:10.1038/sj.leu.2404488; published online 14 December 2006 [ABSTRACT FROM AUTHOR]

This paper reports a comparative kinetic investigation of the overall reduction of NO in the presence of CO or H2 over supported Pt-, Rh- and Pd-based catalysts. Different activity sequences have been established for the NO+H2 reaction Pt/Al2O3>Pd/Al2O3>Rh/Al2O3 and for the NO+CO reaction Rh/Al2O3>Pd/Al2O3> Pt/Al2O3. It was found that both reactions differ from the rate determining step usually ascribed to the dissociation of chemisorbed NO molecules. The rate enhancement observed for the NO+H2 reaction has been mainly related to the involvement of a dissociation step of chemisorbed NO molecules assisted by adjacent chemisorbed H atoms. The calculation of the kinetic and thermodynamic constants from steady-state rate measurements and subsequent comparisons show that Pd and Rh are predominantly covered by chemisorbed NO molecules in our operating conditions which could explain either changes in activity or in selectivity with the lack of ammonia formation on Rh/Al2O3 during the NO+H2 reaction. Interestingly, Pd and Rh exhibit similar selectivity behaviour towards the production of nitrous oxide (N2O) irrespective of the nature of the reducing agent (CO or H2). A weak partial pressure dependency of the selectivity is observed which can be related to the predominant formation of N2 via a reaction between chemisorbed NO molecules and N atoms, while over Pt-based catalysts the associative desorption of two adjacent N atoms would occur simultaneously. Such tendencies are still observed under lean conditions in the presence of an excess of oxygen. However, a detrimental effect is observed on the selectivity with an enhancement of the competitive H2+O2 reaction, and on the activity behaviour with a strong oxygen inhibiting effect on the rate of NO conversion, particularly on Rh. [ABSTRACT FROM AUTHOR]

Tamoxifen is the standard first-line endocrine therapy for breast cancer, but recent data indicate that it is likely to be replaced by the effective aromatase inhibitors (AIs), in both the metastatic and adjuvant settings. Aromatase inhibitors induce complete oestrogen deprivation that leads to clinically significant bone loss. Several ongoing or planned trials combine AIs with bisphosphonates, even more so that recent data reveal that clodronate may reduce the incidence of bone metastases and prolong survival in the adjuvant setting. Bisphosphonates can inhibit breast cancer cell growth in vitro, but they have never been studied in steroid-free medium (SFM), an in vitro environment that mimics the effects of AIs in vivo. Quite surprisingly, in SFM, clodronate stimulated MCF-7 cell growth in a time- and dose-dependent manner by up to two-fold (crystal violet staining assay), whereas it had no mitogenic activity in complete medium. The bisphosphonate similarly increased the proliferation of IBEP-2 cells, which also express a functional oestrogen receptor (ER), while it weakly inhibited the growth of the ER-negative MDA-MB-231 cells. Expectedly, 17ß-oestradiol stimulated the growth of MCF-7 and IBEP-2 cells cultured in SFM, and had no effect on MDA-MB-231 cells. Moreover, partial (4-OH-tamoxifen) and pure antioestrogens (fulvestrant, ICI 182,780), in combination with clodronate, completely suppressed the mitogenic effect of the bisphosphonate, suggesting that it was mediated by an activation of ER. In accordance with this view, clodronate induced ER downregulation, weakly increased progesterone receptor expression, and stimulated the transcription of an oestrogen-responsive reporter gene. In conclusion, we report a previously unknown stimulatory effect of clodronate on MCF-7 cells grown in SFM, in vitro conditions that are potentially relevant to the use of AIs for breast cancer. Moreover, our data suggest that ER is involved in these effects of clodronate on cancer cell growth.British Journal of Cancer (2004) 91, 1703-1710. doi:10.1038/sj.bjc.6602181 www.bjcancer.com Published online 12 October 2004 [ABSTRACT FROM AUTHOR]

The reduction of CH4 by NO has been investigated in the presence of oxygen on palladium supported on alumina, ceria–zirconia mixed oxides and perovskite materials, mainly LaCoO3. The activation procedure, under oxygen or hydrogen, drastically influences the catalytic performances of both catalysts. The stabilisation of a metallic or oxidic Pd phase leads to poor activity in the conversion of NO in the absence of oxygen. On the other hand, oxygen enhances the activity, particularly on the reduced Pd/LaCoO3, in the CH4 + NO reaction. Such results have been explained by different interactions between palladium and the support. [ABSTRACT FROM AUTHOR]

Class I homeobox (HOX) genes comprise a large family of transcription factors that have been implicated in normal and malignant hematopoiesis. However, data on their expression or function during T-cell development is limited. Using degenerated RT-PCR and Affymetrix microarray analysis, we analyzed the expression pattern of this gene family in human multipotent stem cells from fetal liver (FL) and adult bone marrow (ABM), and in T-cell progenitors from child thymus. We show that FL and ABM stem cells are similar in terms of HOX gene expression, but significant differences were observed between these two cell types and child thymocytes. As the most immature thymocytes are derived from immigrated FL and ABM stem cells, this indicates a drastic change in HOX gene expression upon entry into the thymus. Further analysis of HOX-A7, HOX-A9, HOX-A10, and HOX-A11 expression with specific RT-PCR in all thymocyte differentiation stages showed a sequential loss of 3 ′ region HOX-A cluster genes during intrathymic T-cell development and an unexpected expression of HOX-A11, previously not recognized to play a role in hematopoiesis. Also HOX-B3 and HOX-C4 were expressed throughout thymocyte development. Overall, these data provide novel evidence for an important role of certain HOX genes in human T-cell development. [ABSTRACT FROM AUTHOR]

The intrinsic activity of various Zr xCe1− xO2 mixed oxides and after a Pd deposition has been investigated in the CO + NO reactions from temperature-programmed experiments performed under stoichiometric conditions. It has been found that the activity of Zr xCe1− xO2 depends on either the specific surface area or the number of Ce cations and their intrinsic activity, Zr0.5Ce0.5O2 being the most active support. The addition of palladium strongly enhances the catalytic activity of the supports probably due to a synergistic effect between CeO2 and the metal since the initial activity of palladium-based catalysts is directly related to their Ce content. Such a catalytic enhancement has been explained by a “bifunctional” mechanism involving active sites probably composed of Pd and ceria. A strong deactivation operates leading to the disappearance of the beneficial effect of ceria. Such a deactivation seems to be dependent on the support composition, Pd supported Zr0.25Ce0.75O2 being the most resistant to deactivation. [ABSTRACT FROM AUTHOR]

We have attempted to model the rate of NO transformation on a sintered Pt–Rh/Al2O3 three-way catalyst (TWC) in various temperature and conversion conditions close to the actual ones in TWCs. For this purpose a rate expression, previously established from kinetic measurements performed at a single temperature of 300°C, was used. The temperature dependency of the kinetic and thermodynamic parameters, using a non-linear optimisation, has been previously determined. Then, temperature-programmed experiments, performed in a fixed-bed flow reactor at atmospheric pressure under differential conditions, have been modelled using such parameters. A similar procedure has been achieved for modelling the TP experiments on Rh/Al2O3. Both results have been compared and discussed in the light of previous surface characterisations. [ABSTRACT FROM AUTHOR]

This study was undertaken in order to examine the estrogen sensitivity of HKT-1097, an established cell line recently derived from diethylstilbestrol (DES)-induced kidney tumors in Syrian hamsters. Estrogen receptor (ER) level in HKT-1097, determined by enzyme-linked immunoassay, was 67 fmol/mg protein, i.e., a value approx. 30% lower than that found in Syrian hamster kidney tumors. ER immunostaining in cells fixed with Carnoy's mixture, as well as ER demonstration by Western blotting, suggested DES-induced nuclear translocation or stabilization of the receptor within the nucleus. Kinetic parameters of estrogen binding to ER in HKT-1097 cells were 8.4×10−11 M and 60.8 fmol/mg protein for K d and Bmax, respectively. The K d of estrogen binding to ER in HKT-1097 was close to that evaluated for the receptor in breast cancer-derived MCF-7 cell line, whereas the Bmax value was approx. seven times lower in HKT-1097 as compared to MCF-7. In HKT-1097 cells, antiestrogens ICI 182,780 and RU 58,668 induced ER downregulation and competed with estrogen binding to the receptor. As demonstrated by Western blot analysis, DES exposure led to an increased expression of progesterone receptor (PgR) in HKT-1097 cells. Addition of DES to estrogen-free medium produced a stimulation of growth in both HKT-1097 and MCF-7 cells, but the mitogenic effect was less marked for HKT-1097. Despite the fact that ICI 182,780 and RU 58,668 clearly interact with HKT-1097 cell ER, they appeared unable to suppress DES-induced stimulation of growth and increase of PgR expression. [ABSTRACT FROM AUTHOR]

Treatment of human recombinant estrogen receptor (hER) expressed in yeast with very low concentrations of the cupric ion decreased its ability to bind [3H]estradiol ([3H]E2) and [125I]tamoxifen aziridine (minimal Cu2+ concentration: 1 nM). This decrease was reflected in a loss of immunoreactivity for monoclonal antibodies raised against the hormone binding domain (HBD). An ER recombinant expressing solely the HBD confirmed that the ion operated at this level. Cysteines located within this domain contributed to the inhibitory action of the Cu2+ in view of a partial restoration of the [3H]E2 binding activity with β-mercaptoethanol. Histidines were also implicated since the influence of Cu2+ on the [3H]E2 binding parameters (Scatchard plot analysis) was maintained after oxidation of thiol groups by methyl methanethiosulfonate, and partly reversed by imidazole. [ABSTRACT FROM AUTHOR]

Controlled decomposition studies of the bis(cyclopentadienyl)ditungsten(tetracarbonyl)-dimethylacetylenedicarboxylate (Cp2W2(CO)4(dmad)) under flowing hydrogen show that it totally decomposes at 600 °C for 2 h to give a pure bulk W2C as revealed by X-ray diffraction. Excess oxygen and carbon at the surface are detected by X-ray photoelectron spectroscopy. An in situ temperature-programmed X-ray diffraction experiment performed on Cp2W2(CO)4 (dmad) shows the detection temperature of W2C to be 600 °C, the sample being amorphous or microcrystalline below that temperature. Based on previous results obtained for the decomposition of Cp2Mo2(CO)4(dmad) on the one hand, and thermogravimetric and chromatographic analyses performed on Cp2W2(CO)4 (dmad), on the other, a decomposition scheme of the latter under hydrogen has been proposed. © 1998 Chapman & Hall [ABSTRACT FROM AUTHOR]

Changes in the concentrations and affinities of receptors for oestrogen (ER), progesterone (PR) and epidermal growth factor (EGF-R) were studied in mammary glands of healthy bitches with regard to age, the location in the mammary chain and the stage of the oestrous cycle. Uterus was used as the reference tissue for the evaluation of steroid receptors. Mammary and uterine samples from 7 healthy bitches were taken at five stages of the oestrous cycle in such a way that all the locations in the mammary chain were represented at each stage of the cycle (10 samples/dog). ER, PR and EGF-R were detected by biochemical assays using increasing concentrations of tritiated (steroids) or iodinated (EGF) ligands. A significant direct correlation was found between the ER and PR concentrations for mammary and uterine samples. No significant correlation was found between the steroid receptors and EGF-R concentrations. Mammary ER concentrations were significantly higher in bitches of 5 years of age or older than in younger ones; in posterior glands (4th and 5th pairs) than in anterior glands; and in the mid-luteal phase. Mammary PR did not vary significantly with age or location but was significantly lower in the early luteal phase than in other phases. A similar decrease in PR concentrations was observed in the uterus during the early luteal phase and uterine ER and PR concentrations were very low in the mid-luteal phase. Mammary EGF-R were not significantly higher in the early or mid-luteal phase than in pro-oestrus or anoestrus. The differences observed between the uterine and mammary steroid receptor concentrations during the oestrous cycle could be due to different mechanisms for regulating steroid receptor expression in the two tissues. Mammary EGF-R concentrations may be linked, as in other species, to cellular proliferation and/or to the serum progesterone concentrations. [ABSTRACT FROM AUTHOR]

Treatment of estrogen receptor (ER)-positive mammary tumors with tamoxifen produces a dramatic accumulation of ER in the cell nucleus. We investigated whether this phenomenon might be related to the antitumor activity of the drug. Five tamoxifen derivatives for which an influence on MCF-7 cell growth had previously been established were tested for that purpose; two of them inhibited growth, one was growth-stimulatory, and the remaining two were without significant effect. At 1 μ M all compounds up-regulated ER in the cell nucleus after 3 days of culture, suggesting that the ER accumulation does not predict the response to tamoxifen treatment. An analysis of a tamoxifen-resistant clone (RT×6 cells) under similar experimental conditions led to the same conclusion: the ER level significantly increased in the presence of tamoxifen and its 4-hydroxy metabolite. [ABSTRACT FROM AUTHOR]