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Biomedical subjects

J Dumont

Publications and source records attributed to J Dumont.

At least 19 recordsLinked to original sources
PubMed2006

Comparative effects of interferon-gamma and all- trans retinoic acid on secreted and surface-associated matrix metalloproteinase-9 expression of human monocytes.

Matrix metalloproteinase-9 is involved in inflammation and tumor progression. We previously demonstrated that interferon type I (alpha/beta) and II (gamma) inhibit matrix metalloproteinase-9 (92kDa) gene expression on lymphocytes from patients with B chronic lymphocytic leukemia and human monocytes. Since all-trans retinoic acid (ATRA) can regulate some interferon -responsive genes, we studied here the effects of all-trans retinoic acid onto matrix metalloproteinase-9 levels in these cells. By using RT-PCR, ELISA and zymography experiments, we showed that all-trans retinoic acid down-regulated matrix metalloproteinase-9 synthesis (mRNA,protein) and secretion. The inhibitory action of all-trans retinoic acid toward matrix metalloproteinase-9 was however not associated with the STAT1/IRF-1 pathway involved in interferon-mediated matrix metalloproteinase-9 inhibition indicating that all-trans retinoic acid did not bypass IFN receptor signaling. Using flow cytometry, we detected on the surface of monocytes low expression of matrix metalloproteinase-9 and Fc-gammaRI, and high expression of HLA-DR, beta1 and beta2 integrins. Enhancement of Fc-gammaRI and HLA-DR on monocytes by interferon-gamma, but not by all-trans retinoic acid, was accompanied by up-regulation of surface matrix metalloproteinase-9. Furthermore, we showed that all-trans retinoic acid down-regulated matrix metalloproteinase-9 expression in lymphocytes of untreated patients with early stage B chronic lymphocytic leukemia. Together, our data suggest the potential relevance of all-trans retinoic acid as a pharmacological tool to attenuate matrix metalloproteinase-9 secretion in pathological situations.

Antigens, Surface↗
PubMed2002

Production of matrix metalloproteinase-9 in early stage B-CLL: suppression by interferons.

Besides vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), matrix metalloproteinases (MMPs) play critical roles in angiogenesis, tumor invasion and metastasis. Increased angiogenesis is observed in chronic B lymphocytic leukemia (B-CLL) and published data reported VEGF and bFGF production in this disease. The purpose of this study was to investigate MMP expression in early stage B-CLL. Elevated MMP-9 concentrations were detected by ELISA in the sera of B-CLL patients (median level 250 ng/ml) compared with healthy donors (67 ng/ml) (P < 0.0001), and immunostaining with antibodies against MMP-9 and B cell antigens (CD19, CD23) substantiated the presence of MMP-9 in tumoral B lymphocytes. By using RT-PCR, ELISA and zymography experiments, we confirmed that B-CLL cells expressed and released the pro-form of MMP-9 with Mr 92 kDa (158-1300 pg/ml/10(6) cells/48 h), p-aminophenylmercuric acetate generating a 82 kDa active form. In contrast, the production of MMP-9 by normal counterpart B cells was significantly low (28-169 pg/ml/10(6)cells/48 h). Moreover, B-CLL culture supernatants contained bFGF (median levels 17 pg/ml/10(6) cells/48 h), VEGF (1.4 pg/ml/10(6) cells/48 h) and TNF-alpha (0.2 pg/ml/10(6) cells/48 h). TNF-alpha and VEGF antibodies blocked MMP-9 at the mRNA and protein levels. Interferons (IFNs) type I or type II repressed MMP-9 gelatinolytic activity in a dose and time dependency, and this was reflected by a parallel inhibition of MMP-9 mRNA and protein. IFNs however did not affect the production of bFGF, VEGF and TNF-alpha. Together, our data show that B-CLL lymphocytes synthesize MMP-9 and emphasize the specific inhibitory actions of IFNs on its expression.

Case-Control Studies↗
PubMed2001

Conductivity of underdoped YBa(2)Cu(3)O(7-delta): evidence for incoherent pair correlations in the pseudogap regime.

A two-channel scenario for the conductivity of underdoped YBa 2Cu 3O (7-delta) is proposed. One is the single-particle excitations channel, which dominates in the optimally doped material, whose resistivity is linear as a function of temperature. The other one gives a contribution which merges the 3D Aslamazov-Larkin fluctuation conductivity at low temperature and obeys a power law at high temperature, depending on two superconductive parameters (T(c) and the zero temperature coherence length xi(c0)) and an energy scale Delta(*). This allows one to address the nature of the pseudogap in favor of incoherent pairing.

Journal Article↗
PubMed2001

Non-Hodgkin's lymphoma of the testis: a retrospective study of 84 patients treated in the French anticancer centres.

Primary non-Hodgkin's lymphoma of the testicle is rare. We analysed cases treated in French anticancer centres from 1969 to 1995. All cases were reviewed and classified according to the R.E.A.L. Classification. Eighty-four cases were included in this study. The median age was 67 years (17-85). Disease was classified as stages I in 42 cases, stages II in 19 and stages III-IV in 23. Diffuse large B-cell lymphoma was diagnosed in 75% of cases. Treatment included orchidectomy and radiotherapy and/or chemotherapy. A complete response was obtained in 72.6% of the patient population and in 100%, 68% and 33% of stage I, II and III-IV disease respectively. Recurrence occurred in 32 cases and the most frequent site was the central nervous system: six of these patients presented stage I disease. Median overall survival was 32 months for the entire population, 52 months for stage I, 32 months for stage II, and 12 months for stage III-IV cases (P < 0.0001). Among patients presenting stage I disease, no difference was found between those treated with combined surgery and chemotherapy or surgery followed or not followed by radiotherapy. This study confirms that non-Hodgkin's lymphoma of the testicle carries a poor prognosis. Systemic adjuvant chemotherapy should be discussed because of the high recurrence rate. Inclusion of these cases in large co-operative prospective studies is recommended.

Adolescent↗
PubMed2001

HMGI-C gene expression is not required for in vivo thyroid cell transformation.

We have previously demonstrated that HMGI proteins are required for the transformation of rat thyroid cells by v-mos and v-ras-Ki oncogenes. To determine whether HMGI proteins are also required for in vivo thyroid carcinogenesis, mice carrying a disrupted HMGI-C gene (pygmy mice) were either treated with radioactive iodine or crossed with transgenic mice carrying the E7 papilloma virus oncogene under the transcriptional control of thyroglobulin gene promoter. The pygmy mice developed thyroid carcinomas with the same frequency as occurred in wild-type mice without significant macroscopic and microscopic differences. Therefore, these results indicate that HMGI-C gene expression is not required in in vivo thyroid cell malignant transformation.

Animals↗
PubMed2001

Localization of surface immunogenic protein on group B streptococcus.

The localization and accessibility of the group B streptococcus (GBS) surface immunogenic protein (Sip) at the surface of intact GBS cells were studied by flow cytometric assay and immunogold electron microscopy. Antibodies present in pooled sera collected from mice after immunization with purified recombinant Sip efficiently recognized native Sip at the surfaces of the different GBS strains tested, which included representatives of all nine serotypes. Examination of GBS cells by immunogold electron microscopy revealed that the Sip-specific antibodies attached preferentially to polar sites and the septal region. This result confirmed that Sip is exposed at the intact-cell surface, but it also suggests that its distribution is restricted to certain regions of the cell.

Animals↗
PubMed2000

Regulation of CD26/DPPIV gene expression by interferons and retinoic acid in tumor B cells.

Interferons (IFNs alpha, beta and gamma) and all trans retinoic acid (RA) have the ability to activate genes with GAS sites. We have found that the promoter of CD26/dipeptidylpeptidase IV (DPPIV) contains a consensus GAS site TTCnnnGAA located at bp-35 to -27, and computer analysis confirmed this sequence to be a putative Stat binding site. Consistent with this finding, we show that IFNs and RA rapidly enhanced CD26 gene and protein expression in chronic B lymphocytic leukemia (B-CLL) cells. Immunoblot analyses revealed that unstimulated B-CLL cells expressed detectable levels of serine/tyrosine-phosphorylated Stat1alpha, and RA and IFN-gamma treatment led to increased levels of tyrosine phosphorylation of Stat1alpha and its nuclear accumulation. As shown by electrophoretic mobility shift assay, RA and IFN-gamma increased the binding of a nuclear protein to the GAS-CD26 element. Shift-Western blotting identified Stat1alpha as the GAS-CD26 binding factor. Augmented levels of CD26 protein in malignant B cells cultured with IFNs or RA coincided with the enhancement of DPPIV activity. Taken together, our results are in favor of the IFN-/RA-mediated upregulation of CD26/DPPIV in B-CLL through the signaling pathway involving Stat1alpha and the GAS response element of CD26 promoter.

Cell Separation↗
PubMed2000

Cold-adapted enzymes: from fundamentals to biotechnology.

Psychrophilic enzymes produced by cold-adapted microorganisms display a high catalytic efficiency and are most often, if not always, associated with high thermosensitivity. Using X-ray crystallography, these properties are beginning to become understood, and the rules governing their adaptation to cold appear to be relatively diverse. The application of these enzymes offers considerable potential to the biotechnology industry, for example, in the detergent and food industries, for the production of fine chemicals and in bioremediation processes.

Adaptation, Physiological↗
PubMed1999

Constitutive expression of CD26/dipeptidylpeptidase IV on peripheral blood B lymphocytes of patients with B chronic lymphocytic leukaemia.

We have investigated the expression of the ectoenzyme dipeptidylpeptidase IV (DPP IV)/CD26 on lymphocytes obtained from patients with B chronic lymphocytic leukaemia (B-CLL) and compared it with healthy subjects. Using two-colour immunofluorescence analysis with CD26 and CD20 or CD23 monoclonal antibodies, CD26 was found undetectable on peripheral resting B-cells (CD20+ CD23-) from normal donors whereas it was expressed on B-cells activated in vitro with interleukin (IL)-4 and Staphylococcus aureus strain cowan I (CD20+ CD23+). The expression of CD26 on leukaemic B-cells (CD20+ CD23+) was clearly induced in 22 out of 25 patients examined. Consequently, induced levels of CD26 cell surface expression on either normal activated and malignant B-cells coincided with the enhancement of DPP IV activity detected on the surface of these cells. Reverse transcription polymerase chain reaction analyses showed that the transcript levels of the CD26 gene was higher in normal activated B-cells and B-CLL cells than in resting B-cells, suggesting that CD26 was expressed at the level of transcriptional activation. These observations provide evidence of the abnormal expression of DPPIV/CD26 in B-CLL which, therefore, may be considered as a novel marker for B-CLL. Further investigation in relation to CD26 expression and other B malignancies needs to be defined.

Adult↗
PubMed1999

Increased sensitivity of CLL-derived lymphocytes to apoptotic death activation by the proteasome-specific inhibitor lactacystin.

Ubiquitin-proteasome-dependent protein processing appears to be an essential component in the control of radiation-induced apoptosis in human lymphocytes. This control is altered in chronic lymphocytic leukaemia (CLL), compared to that of normal human lymphocytes which mainly showed high apoptotic values after irradiation, but in some cases no sensitivity was observed. Interestingly, lactacystin activated the apoptotic pathway in both radio-resistant and sensitive CLL cells, at doses which had no effect in normal cells where significantly higher concentrations were required. Therefore the resistance of some CLL cells to apoptosis initiation by radiation does not correlate to observed increased sensitivity to lactacystin. The nuclear level of the transcription factor NF-kappaB or the cytoplasmic level of IkappaBalpha remained unaltered upon irradiation or lactacystin CLL cells treatment, suggesting that the activity of the other factors involved in apoptotic death control were altered through proteasomal inhibition. These results strongly suggest an essential role of the ubiquitin system in apoptotic cell death control in CLL lymphocytes. The inhibition of proteasome-ubiquitin-dependent processing could be a discriminatory apoptotic stimulus between normal versus malignant lymphocytes and therefore might potentially be of use in this specific human pathology.

Acetylcysteine↗
PubMed1999

[Promoting health in health care organizations and hospitals? A survey of the French community in Belgium].

Health promotion concept and practices have brought many significant changes even in disease management and care settings. In the Ottawa charter, health promotion is defined as "the process of enabling people to increase control over, and to improve, their health". However, care settings are in contradiction with this process on several levels (focus on disease and not enough on health, concern more on cure than on care, etc.). The emergence of health promotion practices has been deeply questioning these features. Care institutions start to reconsider their role and missions. However, changes are slow and there has been much resistance. What is the current situation of health promotion in French speaking Belgian care institutions in 1998? The WHO EUROPE HEALTH PROMOTING HOSPITALS' (HPH) project, which officially started in 1991, aims at "promoting positive health and well-being in hospitals and beyond that, in the community". For each participating hospital, the implications of membership have an important influence on the institution and care project, because it implies adherence to the principles of the Ottawa charter on health promotion, and to the philosophy and objectives of HPH. Belgium joined the WHO project and the HPH network in 1996. It was necessary to review the situation of health care institutions in the French speaking community of Belgium in order to understand the evolution over the last years, to assess health professionals expectations and the feasibility of some actions, and to provide political decision makers with information likely to influence future decisions and choices in a positive way. This article presents the descriptive results of a survey carried out on nursing and patient education departments in health care institutions. Half of 105 hospitals answered the questionnaires sent. Out of these answers, 150 projects and actions were identified and briefly described by the institutions, which had the possibility to present a maximum of five actions. The main topics addressed were chronic diseases, psychology (conflict management, aggressiveness, ill-treatment), maternity, screening, prevention and vaccination. Regarding perspectives, 78% of actions concern disease and/or risks of disease (therapeutic or preventive perspectives) and 22% concern the maintenance or improvement of health. 90% of listed and described actions are permanent, and only 10% are selective (limited), which suggests an evolution of projects and their integration in practices. Concerning the number of projects, two aspects were analysed: the number by institution and the evolution over the last twenty years. On average, there are 3.2 actions per institution. As for the evolution, 7% of hospitals said they had at least one education action/project in 1980, 60% in 1990 and 98% in 1998. This amazing and remarkable evolution occurred simultaneously to the development of education committees, of patient education co-ordinators and/or resource persons. In this field, there was also a remarkable evolution since the creation of the first committees in 1983. Amongst the elements encouraging the development of information and health education initiatives and actions mentioned by hospital managers, the first one is a demand from the public (and patients). It is the first time, since the existence of such surveys that this factor is mentioned as the most important.

Attitude of Health Personnel↗
PubMed1999

Mature full-thickness articular cartilage explants attached to bone are physiologically stable over long-term culture in serum-free media.

Mature tissue explants containing the entire depth of articular cartilage, calcified and uncalcified, attached to a thin layer of subchondral bone were isolated from bovine humeral heads of 1-2-year-old steers. These explants were placed in defined serum-free culture medium for a period of 3 weeks to investigate their biological and mechanical stability and thus to determine their potential utility in studies of cartilage physiology. Tissue mass remained constant over the culture period and no evident tissue swelling or distortion was observed. Chondrocytes were viable in all zones at the time of tissue isolation and throughout the culture period, with the exception of a thin layer of cells at the articular surface and the cut radial edge of the disks. Proteoglycan metabolism attained a steady state after 5 days of culture when the rate of loss of proteoglycan to culture media was compensated by new synthesis to maintain a stable proteoglycan content. Collagen metabolism was also stable with a constant content of type II collagen and a constant content of denatured collagen II throughout culture; the content of the C-propeptide of type II procollagen as a measure of procollagen synthesis, dropped slightly during the first week to attain a steady state after that time. Dynamic and equilibrium mechanical properties of these explant disks were also stable confirming maintenance of these tissue properties during long-term culture. In addition, the disk geometry of the system, with the cut surface in the bone parallel to the intact articular surface, is well-suited to study tissue regulation by mechanical load. Taken together, the stability of these indicators of tissue physiology indicates the maintenance in serum-free conditions of normal metabolism for organ cultures containing full-depth mature articular cartilage attached to bone.

Animals↗
PubMed1998

Comparative analysis of apoptosis measured by Hoechst and flow cytometry in non-Hodgkin's lymphomas.

Fine-needle samples of 75 non-Hodgkin's lymphomas were investigated for apoptosis immediately and after 24 h of culture after in vitro irradiation (2 Gy, 10 Gy, and nonirradiated controls). Apoptotic cells were simultaneously quantified by fluorescence microscopic enumeration of apoptotic cells using Hoechst 33342 staining, and by flow cytometric detection of sub-G1 peak cells. The nonirradiated controls showed a similar mean percent apoptotic cells using both methods, analyzed immediately (9% by morphology vs. 10% by flow) or after 24 h of culture (40% by morphology vs. 41% by flow). In the irradiated samples, the mean percent apoptotic cells quantified by morphology was higher than by flow cytometry (64% by morphology vs. 55% by flow after 2 Gy irradiation, and 71% vs. 58% after 10 Gy). The results of the two methods were correlated, although large differences were seen between the techniques in individual tumors. In our system, flow cytometric sub-G1 peak analysis appears to underestimate apoptosis. Of these two methods, we find the Hoechst morphology method to be more reliable for quantitation of apoptosis utilizing fresh fine-needle sample material, in that discrimination of apoptotic cells from debris is easier and that both early and late apoptotic cells are detectable.

Apoptosis↗
PubMed1998

In vitro radiation-induced apoptosis and early response to low-dose radiotherapy in non-Hodgkin's lymphomas.

PURPOSE: Prospective investigation of spontaneous and in vitro radiation-induced apoptosis to predict early response to palliative radiotherapy in patients with non-Hodgkin's lymphomas. PATIENTS AND METHODS: Fine-needle sampling was performed in 28 tumor sites (26 patients) and yielded adequate cell numbers in 27 cases. Apoptotic cells were counted by fluorescence microscopy immediately after sampling and after 24-h culture (spontaneous apoptosis) and 24 h after 2- and 10-Gy in vitro irradiation (radiation-induced apoptosis). Early response to low-dose in vivo radiotherapy (mostly 4 Gy in two fractions over 3 days) was evaluated 15 days after treatment. RESULTS: The tumor response rates at 15 days were 11 (39%) complete responses, nine (32%) responses of greater than 50% reduction in volume, six (21%) responses of less than 50% reduction in volume and two (7%) cases of no response. Tumors achieving complete or major response after in vivo irradiation had higher percentages of apoptotic cells after in vitro irradiation, while no significant differences in terms of spontaneous apoptosis were observed between responders and non-responders. CONCLUSION: Spontaneous and in vitro radiation-induced apoptosis can be easily and quickly assessed on cells obtained by fine-needle sampling of non-Hodgkin's lymphoma lesions. The present results suggest that in vitro radiation-induced apoptosis could be used as a predictive assay of early response to low-dose in vivo irradiation in patients with non-Hodgkin's lymphomas.

Adult↗
PubMed1998

Calcium binding protein calcyphosine in dog central astrocytes and ependymal cells and in peripheral neurons.

Calcyphosine is a calcium binding protein discovered in the dog thyroid in 1979. Calcyphosine mRNA and immunoreactivity were detected using Western and Northern blotting in the cerebral cortex, cerebral white matter and cerebellum. Using immunohistochemistry and in situ hybridization, both are present in ependymal cells, choroid plexus cells and several types of astrocytes of the subependymal cerebral layer, the cerebellar Bergmann layer, the retinal ganglion cell layer, the optic nerve and the posterior pituitary. Both are also present in neurons of nasal olfactory mucosa, enteric Auerbach and Meissner plexuses, orthosympathic and spinal cord ganglia as well as in endocrine cells of neural crest origin in the adrenal medulla. Calcyphosine immunoreactive astrocytes were also present mainly in hemispheric cerebral gray and white matter, hemispheric subcortical structures, brain stem and spinal cord. These results show that calcyphosine is a characteristic calcium binding protein of astrocytes and ependymal cells in the central nervous system and of neurons in the peripheral nervous system. This is of interest in view of the importance of calcium regulation in these cells, and since calcyphosine a calcium binding protein phosphorylated by cAMP dependent process, may be an intermediate between cAMP and inositol phosphate cascades.

Animals↗
PubMed1998

The proteasome inhibitor lactacystin induces apoptosis and sensitizes chemo- and radioresistant human chronic lymphocytic leukaemia lymphocytes to TNF-alpha-initiated apoptosis.

Apoptosis can be triggered by cytotoxic agents and radiation currently used in cancer treatment. However, the apoptotic response appears to vary between cell types (normal or transformed) and between types of malignancy. Thus, irradiation induces apoptosis in normal human lymphocytes but not in lymphocytes derived from a subset of chronic lymphocytic leukaemia (CLL). Moreover, in this subset, spontaneous apoptosis is inhibited by irradiation. Why irradiation does not allow the initiation of the apoptotic death pathway could be explained, at least in part, and in agreement with recent findings on experimental models, by the activation of the transcriptional factor NF-kappaB, which is able to inhibit apoptotic cell response. Low doses (at which no effect is observed with normal human lymphocytes) of the highly specific proteasome inhibitor lactacystin are sufficient to trigger apoptosis in these malignant cells. Proteasome inhibition by lactacystin prevents the nuclear translocation of both p50 and p65 NF-kappaB subunits and sensitizes these cells to apoptosis by tumour necrosis factor (TNF)-alpha treatment. As this subset of CLL is totally resistant to any treatment, proteasome inhibition by lactacystin provides a new therapeutic approach to be explored, considering the sensitivity of malignant CLL-derived lymphocytes to be quite different from that of normal human lymphocytes.

Acetylcysteine↗