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See detailPositive and Negative Ion Formation in Ketene by Electron Impact
Collin, Jacques ULg; Locht, Robert ULg

in International Journal of Mass Spectrometry and Ion Physics (1970), 3

Dissociation processes leading to positive and negative ions in ketene are discussed on the basis of appearance potential measurements. All important positive and negative ions are examined. For the ... [more ▼]

Dissociation processes leading to positive and negative ions in ketene are discussed on the basis of appearance potential measurements. All important positive and negative ions are examined. For the negative ions, only resonance dissociative attachment processes are considered. Excited electronic states of negative ions, in particular for O-, may explain the structure observed in the dissociative attachment efficiency curves. [less ▲]

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See detailPositive and negative ion mode ESI-MS and MS/MS for studying drug-DNA complexes
Rosu, Frédéric ULg; Pirotte, Sophie ULg; De Pauw, Edwin ULg et al

in International Journal of Mass Spectrometry (2006), 253(3), 156-171

We report systematic investigation of duplex DNA complexes with minor groove binders (Hoechsts 33258 and 33342, netropsin and DAPI) and intercalators (daunomycin, doxorubicin, actinomycin D, ethidium ... [more ▼]

We report systematic investigation of duplex DNA complexes with minor groove binders (Hoechsts 33258 and 33342, netropsin and DAPI) and intercalators (daunomycin, doxorubicin, actinomycin D, ethidium, cryptolepine, neocryptolepine, m-Amsacrine, proflavine, ellipticine and mitoxantrone) by ESI-MS and ESI-MS/MS in the negative ion mode and in the positive ion mode. The apparent solution phase equilibrium binding constants can be determined by measuring relative intensities in the ESI-MS spectrum. While negative ion mode gives reliable results, positive ion mode gives a systematic underestimation of the binding constants and even a complete suppression of the complexes for intercalators lacking functional groups capable of interacting in the grooves. In the second part of the paper we systematically compare MS/MS fragmentation channels and breakdown curves in the positive and the negative modes, and discuss the possible uses and caveats of MS/MS in drug-DNA complexes. In the negative mode, the drugs can be separated in three groups: (1) those that leave the complex with no net charge; (2) those that leave the complex with a negative charge; and (3) those that remain attached on the strands upon dissociation of the duplex due to their positive charge. In the positive ion mode, all complexes fragment via the loss of protonated drug. Information on the stabilization of the complex by drug-DNA noncovalent interactions can be obtained straightforwardly only in the case of neutral drug loss. In all other cases, proton affinity (in the positive ion mode), gas-phase basicity (in the negative ion mode) and coulombic repulsion are the major factors influencing the fragmentation channel and the dissociation kinetics. [less ▲]

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See detailPositive control of ammonia-sensitive permeases by the positive regulatory factor NPR1
Vandenbol, Micheline ULg; Jauniaux, J. C.; Vissers, S. et al

Poster (1986)

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See detailPositive curvature effects and interparticle capillary condensation during nitrogen adsorption in particulate porous materials
Gommes, Cédric ULg; Ravikovitch, Peter; Neimark, Alexander

in Journal of Colloid and Interface Science (2007), 314

The adsorption of nitrogen in a collection of spheres that touch or merge in a sintering-like manner is modeled using a Derjaguin–Broeckhof–de Boer approach. The proposed model accounts for both positive ... [more ▼]

The adsorption of nitrogen in a collection of spheres that touch or merge in a sintering-like manner is modeled using a Derjaguin–Broeckhof–de Boer approach. The proposed model accounts for both positive curvature effects and for capillary condensation at the contact between two spheres. A methodology is proposed to fit the P/P0 > 0.4 adsorption region with the coordination number of the spheres as the only adjustable parameter. The use of the model is illustrated on a series of silica aerogels. The suitability of various standard isotherms needed for the modeling is also discussed. [less ▲]

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See detailPositive effects of glucocorticoids on T cell function by upregulation of interleukin-7 receptor alpha
Franchimont, Denis; Galon, Jérôme; Vacchio, Melanie S. et al

in Journal of Immunology (2002), 168

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See detailPositive effects of strontium ranelate on spine osteoarthritis progression
Bruyère, Olivier ULg; Delferriere, D.; Roux, C. et al

in Annals of the Rheumatic Diseases (2007, July), 66(Suppl.II), 58

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See detailPositive impact of compliance to strontium ranelate on the risk of non-vertebral osteoporotic fractures
Rabenda, Véronique ULg; Reginster, Jean-Yves ULg

in Osteoporosis International (2009, March), 20(Suppl.1), 89

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See detailPositive impact of compliance to strontium ranelate on the risk of nonvertebral osteoporotic fractures.
Rabenda, Véronique ULg; Reginster, Jean-Yves ULg

in Osteoporosis International (2010), 21(12), 1993-2002

Adherence is now one of the major issues in the management of osteoporosis. This paper relates the relationship existing between adherence to strontium ranelate and the risk of subsequent nonvertebral ... [more ▼]

Adherence is now one of the major issues in the management of osteoporosis. This paper relates the relationship existing between adherence to strontium ranelate and the risk of subsequent nonvertebral fracture among postmenopausal women with osteoporosis. INTRODUCTION: The aim of this study is to investigate compliance to strontium ranelate (SR) therapy and the impact of compliance on the risk of nonvertebral fractures among women with osteoporosis. METHODS: This study was a post-hoc analysis of pooled data from two international, phase III, randomized, placebo-controlled, double-blind studies (the Spinal Osteoporosis Therapeutic Intervention and Treatment Of Peripheral Osteoporosis). A nested case-control study was performed in the strontium ranelate-treated population. Compliance was quantified using the medication possession ratio (MPR). RESULTS: Two hundred eighty-five nonvertebral fracture cases (hip fx n = 70; major nonvertebral fx n = 213) were identified and matched to 1,425 controls. The mean MPR was 86.8% for controls and 82.6% for cases (p < 0.001). Women who were compliant to SR had a 38% reduction in all nonvertebral fractures compared with those who were not (OR = 0.62; 95%CI[0.47-0.81; p < 0.001). Considering hip fractures only, the risk was reduced by 50% for compliant patients compared to noncompliant patients (OR = 0.50; 95%CI[0.28-0.88]; p < 0.05). CONCLUSION: Our analyses emphasize the importance of good compliance to treatment in order to reduce the risk of osteoporotic fractures. In particular, there was a greater reduction in the risk of nonvertebral and hip fractures with increase compliance. [less ▲]

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See detailPositive interactive radiosensitization observed in vitro with the combination of two nucleoside analogs (E)-2'-deoxy-2'-(fluoromethylene) cytidine (FMdC) and iododeoxyuridine (IdUrd).
Coucke, Philippe ULg; Cottin, E; Azria, D et al

in European Journal of Cancer (2004)

(E)-20-Deoxy-20-(fluoromethylene) cytidine (FMdC), an inhibitor of ribonucleotide diphosphate reductase (RR), is a potent radiation-sensitiser acting through alterations in the deoxyribonucleoside ... [more ▼]

(E)-20-Deoxy-20-(fluoromethylene) cytidine (FMdC), an inhibitor of ribonucleotide diphosphate reductase (RR), is a potent radiation-sensitiser acting through alterations in the deoxyribonucleoside triphosphate (dNTP) pool in the de novo pathway to DNA synthesis. The activity of thymidine kinase (TK), a key enzyme in the ‘salvage pathway’, is known to increase in response to a lowering of dATP induced by FMdC. Nucleoside analogues such as iododeoxyuridine (IdUrd) are incorporated into DNA after phosphorylation by TK. Radiation sensitisation by IdUrd depends on IdUrd incorporation. Therefore, we have investigated the radiosensitising effect of the combination of FMdC and IdUrd on WiDr (a human colon cancer cell-line) and compared it to the effect of either drug alone. We analysed the effects of FMdC and IdUrd on the dNTP pools by high-performance liquid chromatography, and measured whether the incorporation of IdUrd was increased by FMdC using a [125I]-IdUrd incorporation assay. The combination in vitro yielded radiation-sensitiser enhancement ratios of >2, significantly higher than those observed with FMdC or IdUrd alone. Isobologram analysis of the combination indicated a supra-additive effect. This significant increase in radiation sensitivity with the combination of FMdC and IdUrd could not be explained by changes in the dNTP pattern since the addition of IdUrd to FMdC did not further reduce the dATP. However, the increase in the radiation sensitivity of WiDr cells might be due to increased incorporation of IdUrd after FMdC treatment. Indeed, a specific and significant incorporation of IdUrd into DNA could be observed with the [125I]-IdUrd incorporation assay in the presence of 1 lM unlabelled IdUrd when combined with FMdC treatment. 2004 Elsevier Ltd. All rights reserved. [less ▲]

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See detailPositive parity pentaquarks in a Goldstone boson exchange model
Stancu, Floarea ULg

in Physical Review. D : Particles and Fields (1998), D58

We study the stability of the pentaquarks $uudd\overline{Q}$, $uuds\overline{Q}$ and $udss\overline{Q}$ ($Q = c$ or $b$) of positive parity in a constituent quark model based on Goldstone boson exchange ... [more ▼]

We study the stability of the pentaquarks $uudd\overline{Q}$, $uuds\overline{Q}$ and $udss\overline{Q}$ ($Q = c$ or $b$) of positive parity in a constituent quark model based on Goldstone boson exchange interaction between quarks. The pentaquark parity is the antiquark parity times that of a quark excited to a p-shell. We show that the Goldstone boson exchange interaction favors these pentaquarks much more than the negative parity ones of the same flavour content but all quarks in the ground state. We find that the nonstrange pentaquarks are stable against strong decays. [less ▲]

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See detailA positive response to infliximab in Crohn disease: Association with a higher systemic inflammation before treatment but not with-308 TNF gene polymorphism
Louis, Edouard ULg; Vermeire, S.; Rutgeerts, P. et al

in Scandinavian Journal of Gastroenterology (2002), 37(7), 818-824

Background: Two-thirds to three-fourths of patients with either refractory luminal or fistulizing Crohn disease respond to infliximab treatment. The ability or inability to respond seems to persist over ... [more ▼]

Background: Two-thirds to three-fourths of patients with either refractory luminal or fistulizing Crohn disease respond to infliximab treatment. The ability or inability to respond seems to persist over time. Biological characteristics and/or genetic background can influence the response to treatment. The aim was to assess the value of C-reactive protein and TNF-alpha serum levels before treatment as well as the TNF -308 gene polymorphism in the prediction of response to infliximab treatment in Crohn disease. Methods: Two-hundred-and-twenty-six Crohn disease patients treated in the setting of an expanded access programme to infliximab in Belgium were studied. There were 136 refractory luminal diseases and 90 refractory fistulizing diseases. Luminal diseases were treated with one single infusion; fistulizing diseases with three infusions at weeks 0, 2 and 6. A clinical response to treatment was defined as either a Crohn disease activity index <150 (complete) or a drop of 70 points (partial) at week 4, for luminal disease, and as either complete fistula healing (complete) or a decrease of at least 50% of the number of draining fistulas on two consecutive visits between weeks 0 and 18, for fistulizing disease. CRP and serum TNF-α levels were measured at week 0 before treatment and were compared between responders and non- responders. Patients were genotyped for the -308 TNF gene polymorphism, and allelic as well as genotype frequencies were compared between responders and non- responders. Results: There were 73.2% responders (46.4% complete and 26.8% partial) and 26.8% non- responders. Response rates were similar in luminal and fistulizing diseases. CRP level before treatment was significantly higher in responders than in non-responders (16.8 mg/l (5-160) versus 9.6 mg/l (5-143); P = 0.02). Furthermore, response rate was significantly higher in patients with elevated CRP (> 5 mg/l) than in patients with a normal CRP value (< 5 mg/l) before treatment (76% versus 46%; P = 0.004; OR: 0.26 (0.11-0.63)). Allelic and genotype frequencies for -308 TNF gene polymorphis m were not significantly different between responders and non- responders - with the exception of a slightly higher TNF2 frequency in nonresponders in luminal disease (22.1% versus 11.6%; P = 0.04). However, this was not associated with a significant difference in genotype frequencies. Conclusion: A positive clinical response to infliximab was associated with a higher CRP level before treatment in our population of Crohn disease patients, but there was no relevant association with -308 TNF gene polymorphism. We therefore suggest that CRP level may help to identify better candidates for infliximab treatment. [less ▲]

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See detailPositively Cooperative Binding of Zinc Ions to Bacillus cereus 569/H/9 beta-Lactamase II Suggests that the Binuclear Enzyme Is the Only Relevant Form for Catalysis
Jacquin, Olivier ULg; Balbeur, Dorothée ULg; Damblon, Christian ULg et al

in Journal of Molecular Biology (2009), 392(5), 1278-1291

Metallo-beta-lactamases catalyze the hydrolysis of most beta-lactam antibiotics and hence represent a major clinical concern. While enzymes belonging to subclass B1 have been shown to display maximum ... [more ▼]

Metallo-beta-lactamases catalyze the hydrolysis of most beta-lactam antibiotics and hence represent a major clinical concern. While enzymes belonging to subclass B1 have been shown to display maximum activity as dizinc species, the actual metal-to-protein stoichiometry and the affinity for zinc are not clear. We have further investigated the process of metal binding to the beta-lactamase H from Bacillus cereus 569/H/9 (known as BcII). Zinc binding was monitored using complementary biophysical techniques, including circular dichroism in the far-UV, enzymatic activity measurements, competition with a chromophoric chelator, mass spectrometry, and nuclear magnetic resonance. Most noticeably, mass spectrometry and nuclear magnetic resonance experiments, together with catalytic activity measurements, demonstrate that two zinc ions bind cooperatively to the enzyme active site (with K-1/K-2 >= 5) and, hence, that catalysis is associated with the dizinc enzyme species only. Furthermore, competitive experiments with the chromophoric chelator Mag-Fura-2 indicates K-2 < 80 nM. This contrasts with cadmium binding, which is clearly a noncooperative process with the mono form being the only species significantly populated in the presence of 1 molar equivalent of Cd(II). Interestingly, optical measurements reveal that although the apo and dizinc species exhibit undistinguishable tertiary structural organizations, the metal-depleted enzyme shows a significant decrease in its alpha-helical content, presumably associated with enhanced flexibility. (C) 2009 Elsevier Ltd. All rights reserved. [less ▲]

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See detailPositron Emission Tomographic Study in Alzheimer's Disease and Pick's Disease
Salmon, Eric ULg; Franck, Georges ULg

in Archives of Gerontology and Geriatrics. Supplement (1989), 1

Positron Emission Tomography has been used to compare patients with Alzheimer's disease and 3 patients with biopsy-proved Pick's disease to age-matched volunteers. In Alzheimer's disease, there was a ... [more ▼]

Positron Emission Tomography has been used to compare patients with Alzheimer's disease and 3 patients with biopsy-proved Pick's disease to age-matched volunteers. In Alzheimer's disease, there was a trend to a decrease of the metabolism parallel to the severity of the affection. The hypometabolism was predominant in the temporo-parieto-occipital and the middle temporal regions. In 2 cases of Pick's disease with a classical "frontal syndrome", there was an important fronto-temporal hypometabolism, very suggestive of the diagnosis owing to both its location and intensity. A third patient presented with a slowly progressive dysphasia. A left perisylvian hypometabolism was observed before any evident anatomical abnormality. The clinical symptoms evolved to a dementia and the hypometabolism extended to both frontal lobes. [less ▲]

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See detailPositron emission tomography (PET) evaluation of abdominal aortic aneurysm (AAA)
SakalihasanN, Natzi ULg; Van Damme, Hendrik ULg; Gomez, P. et al

in European Journal of Vascular and Endovascular Surgery (2002), 23(5), 431-436

Background: aneurysmal disease is associated with all inflammatory Cell infiltrate and enzymatic degradation of the vessel wall. Aim of the study: to detect increased metabolic activity in abdominal ... [more ▼]

Background: aneurysmal disease is associated with all inflammatory Cell infiltrate and enzymatic degradation of the vessel wall. Aim of the study: to detect increased metabolic activity in abdominal aortic aneurysms (AAA) by means of positron emission tomography (PET-imaging). Study design: twenty-six patients with AAA underwent PET-imaging Results: in tell patients, PET-imaging revealed increased, fluoro-deoxy-glucose (18-FDG) uptake at the level of the aneurysm. Patients with positive PET-imaging had one or more of the following elements in their clinical history: history Of recent non-aortic surgery (n = 4) a painful inflammatory aortic aneurysm (n = 2). moderate low back pain (n = 2), rapid (>5 mm in 6 months) expansion (n = 4), discovery by PET-scan of a previously undiagnosed lung cancer (n = 3) or parotid tumour (n = 1). Five patients with a positive PET scan required urgent surgery within two to 30 days. Among the 16 patients with negative PET-imaging of their aneurysm, only one had recent non-aortic surgery, none of them required urgent surgery, only two had a rapidly expanding AAA, and in only one patient, PET-imaging revealed an unknown lung cancer. Conclusion: these data suggest a possible association between increased 18-FDG uptake and AAA expansion and rupture. [less ▲]

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See detailPositron Emission Tomography (PET) for Staging Low-Grade Non-Hodgkin's Lymphomas (NHL)
Najjar, F.; Hustinx, Roland ULg; Jerusalem, Guy ULg et al

in Cancer Biotherapy & Radiopharmaceuticals (2001), 16(4), 297-304

Although positron emission tomography (PET) imaging is now recognized as a useful tool for staging intermediate and high-grade non-Hodgkin's lymphoma (NHL), few data are available regarding its accuracy ... [more ▼]

Although positron emission tomography (PET) imaging is now recognized as a useful tool for staging intermediate and high-grade non-Hodgkin's lymphoma (NHL), few data are available regarding its accuracy in low grade NHL. We therefore studied 36 patients with histologically proven low-grade NHL. Whole-body 2-(fluorine-18) fluoro-2-deoxy-D-glucose (FDG) PET was performed at the time of initial diagnosis (n = 21) or for disease recurrence (n = 15) prior to any treatment. PET results were compared to those of physical examination and computed tomography (CT). PET studies were read without knowledge of any clinical data. Any focus of increased activity was described and given a probability of malignancy using a 5 point-scale (0: normal to 4: definitively malignant). An individual biopsy was available for a total of 31 lesions. The sensitivity and specificity were 87% and 100% for FDG-PET, 100% and 100% for physical examination and 90% and 100% for CT respectively. In addition, 42 of 97 peripheral lymph node lesions observed by FDG-PET were clinically undetected, whereas the physical examination detected 23 additional nodal lesions. PET and CT both indicated 12 extranodal lymphomatous localizations. FDG-PET showed 7 additional extranodal lesions while 5 additional unconfirmed lesions were observed on CT. Regarding bone marrow infiltration, PET and biopsy were concordant in 24 patients with 11 true positive (TP) and 13 true negative (TN). However PET was FN in 11 patients and no biopsy was performed in one patient. The combination PET/CT/physical examination seems to be more sensitive than the conventional approach for staging low grade NHL. Its sensitivity however is unacceptably low for diagnosing bone marrow infiltration. [less ▲]

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See detailPositron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) for the staging of low-grade non-Hodgkin's lymphoma (NHL).
Jerusalem, Guy ULg; Beguin, Yves ULg; Najjar, F. et al

in Annals of Oncology (2001), 12(6), 825-30

BACKGROUND: Although PET has been shown to be highly sensitive in the primary staging of lymphoma, previous studies with small numbers of patients indicated that low-grade NHL may not always be adequately ... [more ▼]

BACKGROUND: Although PET has been shown to be highly sensitive in the primary staging of lymphoma, previous studies with small numbers of patients indicated that low-grade NHL may not always be adequately detected by PET. We undertook this study to determine factors influencing the detection of lesions by PET in low-grade NHL and to evaluate the utility of PET in this indication. PATIENTS AND METHODS: Forty-two patients underwent conventional staging procedures (clinical examination, oto-rhino-laryngologic examination, computed tomography of the chest, abdomen and pelvis, gastroscopy and bone marrow biopsy as well as whole-body non-attenuation corrected 18F-FDG-PET RESULTS: PET detected 40% more abnormal lymph node areas than conventional staging in follicular lymphoma but was inappropriate for the staging of small lymphocytic lymphoma where it detected less than 58% of abnormal lymph node areas. PET showed more lesions than conventional staging for peripheral (34% more lymph node areas detected) and thoracic lymph node (39% more) areas but not for abdominal or pelvic lymph nodes (26% fewer areas detected). The sensitivity to detect bone marrow infiltration was unacceptably low for PET. In contrast, PET was as effective as standard procedures for the detection of other extranodal localizations, although a few localizations were detected only by PET and a few others only by conventional procedures. CONCLUSIONS: PET may contribute to the management of patients with low-grade follicular NHL. For the other low-grade lymphoma subtypes, the role of PET is less evident. Further studies using PET to evaluate the results of treatment or to diagnose disease recurrence are warranted in low-grade follicular NHL. [less ▲]

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See detailPositron emission tomography imaging for lymphoma.
Jerusalem, Guy ULg; Hustinx, Roland ULg; Beguin, Yves ULg et al

in Current Opinion in Oncology (2005), 17(5), 441-5

PURPOSE OF REVIEW: To review the current role and the limitations of F-fluorodeoxygenase positron emission tomography in the management of lymphoma, with a particular focus on studies published since ... [more ▼]

PURPOSE OF REVIEW: To review the current role and the limitations of F-fluorodeoxygenase positron emission tomography in the management of lymphoma, with a particular focus on studies published since January 2004. RECENT FINDINGS: F-fluorodeoxygenase positron emission tomography should be routinely performed at the initial diagnosis of patients with suffering from Hodgkin's disease because it adds useful informations to conventional staging techniques. Residual F-fluorodeoxygenase uptake is an important prognostic factor after one or a few cycles of chemotherapy, but it is clearly too early to change patient treatment on the basis of F-fluorodeoxygenase positron emission tomography results. F-fluorodeoxygenase positron emission tomography is the best noninvasive imaging technique after treatment; however, it is always indicated to correlate positron emission tomography findings with clinical data, other imaging modalities, a biopsy, or all three to reduce the risk of false positive results. There are some concerns about the positive predictive value of positron emission tomography after treatment, especially in childhood lymphoma. Clinicians should be aware of positron emission tomography findings in specific clinical conditions in this patient population. F-fluorodeoxygenase positron emission tomography combined with computed tomography offers advantages over the two used separately and read side by side. It may be particularly useful for the planning of radiation therapy or for the planning of a surgical biopsy. Several studies have shown that F-fluorodeoxygenase positron emission tomography is definitively superior to Ga scintigraphy. New radiotracers such as F-fluorothymidine may be useful for the noninvasive assessment of proliferation in vivo. SUMMARY: F-fluorodeoxygenase positron emission tomography has become the most important nuclear medicine imaging modality in the field of lymphoma. It should be routinely used in the treatment of lymphoma patients. [less ▲]

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