importance of ecotone modeling for landscape fragmentation assessment.
Conference (1999)Detailed reference viewed: 9 (4 ULg)
Lower Devonian plant mesofossils from Paraná Basin, Brazil: general introduction, description, age significance and correlation with floral succession from Laurussia and Gondwana.
in Rodrigues, M.A.C.; Pereira, E. (Eds.) : Ordovician-Devonian palynostratigraphy in Western Gondwana: update, problems and perspectives. (1999)Detailed reference viewed: 8 (1 ULg)
Sensitizing human cervical cancer cells in vitro to ionizing radiation with interferon β or γ
; ; et al
in Radiation Research (1999), 152(5),Detailed reference viewed: 8 (2 ULg)
The importance of ecotone modelling for landscape fragmentation assessment.
Bogaert, Jan ; ; et al
in Proceedings of the 5th World Congress of the International Association for Landscape Ecology (IALE). (1999)Detailed reference viewed: 9 (1 ULg)
Dynamics of rRNA within the nucleolus: a study by confocal and electron microscopy
Thiry, Marc ; ; et al
in Analytical Cellular Pathology : The Journal of the European Society for Analytical Cellular Pathology (1999), 18
Potentiation of cytotoxicity and radiosensitization of (E)-2'-deoxy-2' (fluoromethylene) cytidine by pentoxifylline in vitro.
; ; et al
in International Journal of Cancer = Journal International du Cancer (1999), 80
(E)-28-deoxy-28-(fluoromethylene) cytidine (FMdC), a novel inhibitor of ribonucleotide-diphosphate reductase, has been shown to have anti-tumor activity against solid tumors and sensitize tumor cells to ... [more ▼]
(E)-28-deoxy-28-(fluoromethylene) cytidine (FMdC), a novel inhibitor of ribonucleotide-diphosphate reductase, has been shown to have anti-tumor activity against solid tumors and sensitize tumor cells to ionizing radiation. Pentoxifylline (PTX) can potentiate the cell killing induced by DNAdamaging agents through abrogation of DNA-damagedependent G2 checkpoint. We investigated the cytotoxic, radiosensitizing and cell-cycle effects of FMdC and PTX in a human colon-cancer cell line WiDr. PTX at 0.25–1.0 mM enhanced the cytotoxicity of FMdC and lowered the IC50 of FMdC from 79 6 0.1 to 31.2 6 2.1 nM, as determined by MTT assay. Using clonogenic assay, pre-irradiation exposure of exponentially growing WiDr cells to 30 nM FMdC for 48 hr or post-irradiation to 0.5 to 1.0 mM PTX alone resulted in an increase in radiation-induced cytotoxicity. Moreover, there was a significant change of the radiosensitization if both drugs were combined as compared with the effect of either drug alone. Cell-cycle analysis showed that treatment with nanomolar FMdC resulted in S-phase accumulation and that such an S-phase arrest can be abrogated by PTX. Treatment with FMdC prior to radiation increased post-irradiation-induced G2 arrest, and such G2 accumulation was also abrogated by PTX. These results suggest that pharmacological abrogation of S and G2 checkpoints by PTX may provide an effective strategy for enhancing the cytotoxic and radiosensitizing effects of FMdC. Int. J. Cancer 80:155–160, 1999. [less ▲]Detailed reference viewed: 7 (1 ULg)
A treatment planning intercomparison of proton and intensity modulated photon radiotherapy.
; ; et al
in Radiotherapy & Oncology (1999), 51(3)
Abstract Purpose: A comparative treatment planning study has been undertaken between standard photon delivery techniques,b intensity modulated photon methods and spot scanned protons in order to ... [more ▼]
Abstract Purpose: A comparative treatment planning study has been undertaken between standard photon delivery techniques,b intensity modulated photon methods and spot scanned protons in order to investigate the merits and limitations of each of these treatment approaches. Methods: Plans for each modality were performed using CT scans and planning information for nine patients with varying indications and lesion sites and the results have been analysed using a variety of dose and volume based parameters. Results: Over all cases, it is predicted that the use of protons could lead to a reduction of the total integral dose by a factor three compared to standard photon techniques and a factor two compared to IM photon plans. In addition, in all but one Organ at Risk (OAR) for one case, protons are predicted to reduce both mean OAR dose and the irradiated volume at the 50% mean target dose level compared to both photon methods. However, when considering the volume of an OAR irradiated to 70% or more of the target dose, little difference could be shown between proton and intensity modulated photon plans. On comparing the magnitude of dose hot spots in OARs resulting from the proton and IM photon plans, more variation was observed, and the ranking of the plans was then found to be case and OAR dependent. Conclusions: The use of protons has been found to reduce the medium to low dose load (below about 70% of the target dose) to OARs and all non-target tissues compared to both standard and inversely planned photons, but that the use of intensity modulated photons can result in similar levels of high dose conformation to that afforded by protons. However, the introduction of inverse planning methods for protons is necessary before general conclusions on the relative efficacy of photons and protons can be drawn. [less ▲]Detailed reference viewed: 35 (6 ULg)
Indices d'aptitude des procédés de production
in Notes de Statistique et d'Informatique (1999), (5), 26
This note describes the main process capability indices and presents some inferential porperties. A numerical example is analysed by Minitab and SAS softwares.Detailed reference viewed: 9 (1 ULg)
Organisations communes de marché : simulation de l'impact de l'Agenda 2000 sur des exploitations-types en Région wallonne
Burny, Philippe ; Dogot, Thomas ;
Book published by Ministère de la Région wallonne, Conseil supérieur wallon de l'Agriculture, de l'Agro-alimentaire et de l'Alimentation (CSWAAA) (1999)Detailed reference viewed: 3 (0 ULg)
Performance of a wheelchair-user population on a running progressive maximal field test
Vanderthommen, Marc ; ; Crielaard, Jean-Michel
in Vanderwoude, L.H.; Hopman, M.T.; Vankemenade, C.H. (Eds.) Biomedical aspects of manuel wheelchair propulsion. The State of the Art II (1999)Detailed reference viewed: 6 (2 ULg)
Guidelines to Adapt the General Principles of the Non-statistical Meta-analysis Method to Specific Fields of Biomedical Research: the Example of Molecular Oncology.
Pasleau, Françoise ; Delvenne, Catherine ;
in Libraries without limits : changing needs – changing roles Proceedings of the 6th European Conference of medical and Health Libraries. (1999)
In most circumstances, considerable time lags before results from biomedical research are integrated in general medical practice are inevitable. Several economic, technical factors and educational ... [more ▼]
In most circumstances, considerable time lags before results from biomedical research are integrated in general medical practice are inevitable. Several economic, technical factors and educational orientation are responsible for this gap. Effective information management at the institutional level, could provide clinicians the means to adopt new perspectives. At present, the link between basic research and clinical application relies upon the motivation of individuals to develop new skills in literature retrieval and analysis and yet their occupational responsabilities inhibit this endeavour. Academic librarians, educated and trained in information and biomedical sciences, have a role in providing physicians with current and readily applicable knowledge from the critical analysis of the literature. The Faculty of Medicine Library is developing a research programme to design an updated and comprehensive picture of the diagnostic and prognostic biological markers in the field of human prostate cancer. The final product is envisioned as a database accessible on the web that will integrate bibliographic analyses and results from prospective and retrospective studies conducted at the University of Liège. As this product is designed to have a direct impact on clinical decision making and patient care, it should guarantee thoroughness, relevancy and objectivity and not become yet another narrative review of the literature. Over the last decade, there has been a movement towards using statistical meta-analyses to synthesize literature. This method has proven to be useful when similar strategies are used to produce similar quantitative outcomes that can be merged for statistical analysis.1 Even though studies in cancer research assess the same model, they are often too fragmented or heterogeneous in their design, methods and instrumentation. Approaches have been developed to conduct non-statistical meta-analysis of such publications.2 Quantitative and qualitative meta-analyses are based on common principles which are largely discussed in the literature. They are related to model development, literature coding, rating references for quality and annotating and synthesizing high quality references. In practice, these basic principles require translation into actual instructions adapted to every domain of biomedical research. Variable definition is a very critical step that governs the quality of subsequent analyses. Specific examples provided illustrate the guidelines acquired from our experience. Il s'écoule souvent un intervalle de temps fort long avant que les nouveaux concepts issus de la recherche biomédicale soient intégrés dans la pratique médicale courante. Les raisons de cette situation sont autant d'ordre économique et technique que culturel. Actuellement, les liens entre la recherche fondamentale et la médecine clinique ne peuvent exister que sur base d'initiatives individuelles et les médecins concernés doivent investir une partie de leur temps dans l'apprentissage des techniques de recherche et d'analyse de la littérature. Une gestion professionnelle de l'information au niveau d'une institution telle qu'un hôpital universitaire devrait par contre inciter davantage de cliniciens à utiliser les ressources de la littérature issue de la recherche biomédicale. C'est pourquoi la Bibliothèque de la Faculté de Médecine de l'Université de Liège propose, à titre expérimental, de créer un prototype de site web consacré à l'étude des marqueurs pronostiques et diagnostiques du cancer de la prostate. Des scientifiques, spécialisés en sciences biomédicales et formés aux techniques de gestion documentaire, fourniront à l'intention des médecins spécialistes et/ou généralistes, voire des patients eux-mêmes, une analyse critique de la littérature en relation directe avec les activités cliniques de l'institution. Notre objectif étant de fournir aux médecins des informations susceptibles d'être utilisées comme bases de décision clinique, notre responsabilité se trouve engagée vis à vis des patients. Nous devrons donc définir une stratégie qui garantisse à la fois l'exhaustivité et la pertinence de l'information traitée et l'objectivité des analyses présentées. Sur base des principes de la méta-analyse,1,2 nous avons conçu un protocole en cinq étapes comprenant: la définition à priori des objectifs, la recherche non biaisée d'information, la définition de critères de sélection des études, l'extraction et la synthèse des données. La difficulté consistera à traduire ces principes en une série de consignes pratiques et techniques et d'en dégager des lignes de conduite générales qui permettront d'étendre cette approche à n'importe quel domaine de la médecine. 1. D'Agostino RB, Weintraub M. Meta-analysis: a method for synthesizing research. Clin Pharmacol Ther 1995;58:605-616 2. Bland CJ, Meurer LN, Maldonado G. A systematic approach to conducting a non-statistical meta-analysis of research literature. Acad Med 1995;70:642-653 [less ▲]Detailed reference viewed: 13 (0 ULg)
Hypertension arterielle et diabete de type 2.
Scheen, André ; ; Weekers, Laurent
in Revue Médicale de Liège (1999), 54(10), 789-95
Diabetes mellitus is frequently associated with arterial hypertension and the combination of both entities markedly increases the vascular risk. In type 2 diabetes, hypertension appears very early ... [more ▼]
Diabetes mellitus is frequently associated with arterial hypertension and the combination of both entities markedly increases the vascular risk. In type 2 diabetes, hypertension appears very early, especially in the presence of obesity, is part of the insulin resistance syndrome, and contributes to high cardiovascular morbidity and mortality rates in this population. Appropriate regulation of blood pressure is crucial in order to reduce not only microangiopathy (nephropathy and retinopathy) but also macroangiopathy (coronary heart disease and stroke) in hypertensive type 2 diabetic patients. Target blood pressure values have been decreased in recent years and should be < 130/85 mmHg, and may be even lower according to recent data. The optimal modalities of pharmacological treatment remain controversial, but obviously several medications are required to reach such objectives in most hypertensive patients with type 2 diabetes. [less ▲]Detailed reference viewed: 83 (0 ULg)
Contribution à l'étude de la santé bucco-dentaire et de son influence sur l'état nutritionnel de sujets institutionnalisés ages de 65 ans et plus.
Doctoral thesis (1999)Detailed reference viewed: 10 (2 ULg)
The value of pretreatment cell kinetic parameters as predictors for radiotherapy outcome in head and neck cancer : a multicenter analysis.
; ; et al
in Radiotherapy & Oncology (1999), 50
Purpose: The aim of this study was to assess the potential of pre-treatment cell kinetic parameters to predict outcome in head and neck cancer patients treated by conventional radiotherapy. Materials and ... [more ▼]
Purpose: The aim of this study was to assess the potential of pre-treatment cell kinetic parameters to predict outcome in head and neck cancer patients treated by conventional radiotherapy. Materials and methods: Data from 11 different centers were pooled. Inclusion criteria were such that the patients received radiotherapy alone, and that the radiotherapy was given in an overall time of at least 6 weeks with a dose of at least 60 Gy. All patients received a tracer dose of either iododeoxyuridine (IdUrd) or bromodeoxyuridine (BrdUrd) intravenously prior to treatment and a tumor biopsy was taken several hours later. The cell kinetic parameters labeling index (LI), DNA synthesis time (Ts) and potential doubling time (Tpot) were subsequently calculated from flow cytometry data, obtained on the biopsies using antibodies against I/BrdUrd incorporated into DNA. Each center carried out their own flow cytometry analysis. Results: From the 11 centers, a total of 476 patients conforming to the inclusion criteria were analyzed. Median values for overall time and total dose were 49 days and 69 Gy, respectively. Fifty one percent of patients had local recurrences and 53% patients had died, the majority from their disease. Median follow-up was 20 months; being 30 months for surviving patients. Multivariate analysis revealed that T-stage, maximum tumor diameter, differentiation grade, N-stage, tumor localization and overall time correlated with locoregional control, in decreasing order of significance. For the cell kinetic parameters, univariate analysis showed that only LI was significantly associated with local control (P=0.02), with higher values correlating with a worse outcome. Ts showed some evidence that patients with longer values did worse, but this was not significant (P=0.06). Tpot showed no trend (P=0.8). When assessing survival in a univariate analysis, neither LI nor Tpot associated with outcome (P=0.4, 0.4, respectively). Surprisingly, Ts did correlate with survival, with longer values being worse (P=0.02). In the multivariate analysis of local control, LI lost its significance (P=0.16). Conclusions: The only pretreatment kinetic parameter for which some evidence was found for an association with local control (the best end-point for testing the present hypothesis) was LI, not Tpot, and this evidence disappeared in a multivariate analysis. It therefore appears that pretreatment cell kinetic measurements carried out using flow cytometry, only provide a relatively weak predictor of outcome after radiotherapy in head and neck cancer. [less ▲]Detailed reference viewed: 16 (7 ULg)
Articulations entre valeur foncière et croissance spatiale de lʼurbanisation : mise au point dʼune méthode de collectes de données et premiers résultats
in Bulletin de la Société Géographique de Liège (1999), 36Detailed reference viewed: 11 (4 ULg)
Prognostic Factors in Urothelial Renal Pelvis and Ureter Tumours: a Multicentre Rare Cancer Network Study
; ; et al
in European Journal of Cancer & Clinical Oncology (1999), 35/5
To assess the prognostic factors in patients with transitional-cell carcinoma of the renal pelvis and/or ureter, a series of 138 patients with transitional-cell carcinoma of the renal pelvis and/or ureter ... [more ▼]
To assess the prognostic factors in patients with transitional-cell carcinoma of the renal pelvis and/or ureter, a series of 138 patients with transitional-cell carcinoma of the renal pelvis and/or ureter was collected in a retrospective multicentre study. 12 patients with distant metastases were excluded from the statistical evaluation. All but 3 patients underwent radical surgery: nephroureterectomy (n = 71), nephroureterectomy and lymphadenectomy (n = 20), nephroureterectomy and partial bladder resection or transurethral resection (n =20), nephrectomy (n =10), and ureterectomy (n = 5). Sixty-one per cent (n = 77) of the tumours were located in the renal pelvis, and 21% (n = 27) in the ureter (both in 22 [17%]). Following surgery, residual tumour was still present in 33 patients (16 microscopic and 17 macroscopic). Postoperative radiotherapy was given to 45 (36%) patients. The median follow-up period was 39 months. In a median period of 9months, 66% of the patients relapsed (34 local, 7 locoregional, 16 regional, and 24 distant). The 5- and 10-year survival were 29% and 19%, respectively, in all patients. In univariate analyses, statistically signi®cant factors in¯uencing the outcome were Karnofsky index, pT-classi®cation, pN-classi®cation, tumour localisation, grade, and residual tumour after surgery. Multivariate analysis revealed that independent prognostic factors in¯uencing outcome were pTclassi ®cation, the existence of residual tumour, and tumour localisation. In patients with urothelial renal pelvis and/or ureter tumours, a radical surgical attitude is mandatory; and the presence of tumour in the ureter is associated with a poorer prognosis. # 1999 Elsevier Science Ltd. All rights reserved. [less ▲]Detailed reference viewed: 21 (6 ULg)
Structure of high-temperature fluid selenium
Raty, Jean-Yves ; ; Gaspard, Jean-Pierre et al
in Physical Review. B : Condensed Matter (1999), 60(4), 2441-24482448
A semiempirical tight-binding energy model is developed for selenium. It includes s and p electrons as well as an empirical description of the dispersion forces that proves necessary at the liquid ... [more ▼]
A semiempirical tight-binding energy model is developed for selenium. It includes s and p electrons as well as an empirical description of the dispersion forces that proves necessary at the liquid densities under study. The band-structure parameters are obtained by fitting abinitio calculations. The simulated liquid structures are in very good agreement with the most recent X-ray scattering and extended X-ray absorption fine-structure experiments in a broad temperature and density range. The Monte Carlo simulations performed show that the complex liquid structures observed result from the breaking and branching of the selenium chains. The total coordination number is shown to result from the balance between one-, two-, and threefold coordinated atoms. The role of these defects is discussed in relationship with the electrical conductivity of the liquid, i.e., the semiconductor-metal and metal-nonmetal transitions observed at high pressures [less ▲]Detailed reference viewed: 10 (2 ULg)
The ribonucleoside diphosphate reductase inhibitor (E)-2'-Deoxy-(fluoromethylene) cytidine, acts as a cytotoxic radiosensitizer on human cancer cell lines in vitro.
Coucke, Philippe ; ; et al
in Cancer Research (1999), 59
ABSTRACT (E)-2*-Deoxy-(fluoromethylene)cytidine (FMdC) is known as an inhibitor of ribonucleoside diphosphate reductase, a key enzyme in the de novo pathway of DNA synthesis. FMdC was tested as a modifier ... [more ▼]
ABSTRACT (E)-2*-Deoxy-(fluoromethylene)cytidine (FMdC) is known as an inhibitor of ribonucleoside diphosphate reductase, a key enzyme in the de novo pathway of DNA synthesis. FMdC was tested as a modifier of radiation response in vitro on a human colon carcinoma cell line (WiDr), and the observed radiosensitization was confirmed on two human cervix cancer cell lines (C33-A and SiHa). Using the clonogenic assay, the effect ratio (ER) at a clinically relevant dose level of 2 Gy was 2.10 (50 nM FMdC), 1.70 (30 nM FMdC), and 1.71 (40 nM FMdC) for the three cell lines WiDr, C33-A, and SiHa, respectively. A more detailed analysis of the importance of timing and concentration of FMdC was done on the WiDr cell line alone, yielding an increased ER(2Gy) with increasing concentration and duration of exposure to the drug, ranging from 1.0 (6 h) to 1.8 (72 h) at 30 nM FMdC and from 1.2 (6 h) to 3.5 (24 h) at 300 nM. We investigated the effect of FMdC on the cellular deoxynucleotide triphosphate pool in WiDr cells and demonstrated a marked depletion of dATP and a significant rise of TTP levels. Cell cycle analysis showed early S-phase accumulation induced by FMdC alone, G2-M block induced by irradiation alone, and an increased accumulation of cells in G2-M if both modalities are used. Our data suggest that FMdC is a radiation response modifier in vitro on different cancer cell lines. The observed radiosensitization may in part be explained by alteration of the deoxynucleotide triphosphate pool, which is consistent with the effect of FMdC on ribonucleoside diphosphate reductase. [less ▲]Detailed reference viewed: 10 (1 ULg)
Examen minéralogique de phosphates de Benguerir (Maroc)
Report (1999)Detailed reference viewed: 6 (0 ULg)