Biomedical subjects

F Blanchard

Publications and source records attributed to F Blanchard.

At least 19 recordsLinked to original sources

PubMed2006

Zoledronic acid activates the DNA S-phase checkpoint and induces osteosarcoma cell death characterized by apoptosis-inducing factor and endonuclease-G translocation independently of p53 and retinoblastoma status.

The molecular mechanisms responsible for the cellular effects of the nitrogen-containing bisphosphonate zoledronic acid (Zol) were assessed on several osteosarcoma cell lines differing in their p53 and retinoblastoma (Rb) status. Zol inhibited cell proliferation and increased atypical apoptosis. The Zol effects on proliferation were due to cell cycle arrest in S and G2/M phases subsequent to the activation of the intra-S DNA damage checkpoint with an increase in P-ATR, P-chk1, Wee1, and P-cdc2 levels and a decrease in cdc25c, regardless of the p53 and Rb status. In addition, the atypic apoptosis induced by Zol was independent of caspase activation, and it was characterized by nuclear alterations, increased Bax expression, and reduced Bcl-2 level. Furthermore, mitochondrial permeability was up-regulated by Zol independently of p53 in association with the translocation of apoptosis-inducing factor (AIF) and endonuclease-G (EndoG). Zol also disturbed cytoskeletal organization and cell junctions and inhibited cell migration and phosphorylation of focal adhesion kinases. The main difficulty encountered in treating cancer relates to mutations in key genes such as p53, Rb, or proteins affecting caspase signaling carried by many tumor cells. We have demonstrated for the first time that zoledronic acid activated the DNA damage S-phase checkpoint and the mitochondrial pathway via AIF and EndoG translocation, and it inhibited cell proliferation and induced cell death, bypassing these potentials mutations. Therefore, zoledronic acid may be considered as an effective therapeutic agent in clinical trials of osteosarcoma in which mutation for p53 and Rb very often occur, and where current treatment with traditional chemotherapeutic agents is ineffective.

Animals↗

PubMed2006

Loss of oncostatin M receptor beta in metastatic melanoma cells.

Oncostatin M (OSM) is an interleukin-6 (IL-6) type cytokine originally described by its capacity to inhibit melanoma proliferation in vitro. Here, the mechanisms involved in resistance to growth inhibition by OSM were analysed for the first time on a large panel of metastatic melanoma cell lines. OSM resistance did not strictly correlate with IL-6, interferon-gamma or tumor necrosis factor-alpha resistance. Rather, it correlated with a specific loss of the OSM receptor-beta (OSMRbeta) subunit, in conjunction with a lower level of histone acetylation in the OSMRbeta promoter region. Treatment of various OSM-resistant melanoma cells with the histone deacetylase inhibitor Trichostatin A increased activity and histone acetylation of the OSMRbeta promoter as well as expression of OSMRbeta mRNA and protein, allowing OSM to activate the signal transducer and activator of transcription 3 (STAT3) and to inhibit proliferation. Other defects associated with OSM resistance were identified at the level of OSMRbeta transcription or protein expression, as well as downstream of or parallel to STAT3 activation. Altogether, our results suggest a role for OSM in the prevention of melanoma progression and that metastatic melanoma cells could escape this growth control by the epigenetic silencing of OSMRbeta.

Acetylation↗

PubMed2006

XPS valence characterization of lithium salts as a tool to study electrode/electrolyte interfaces of Li-ion batteries.

X-ray photoelectron valence spectra of lithium salts LiBF4, LiPF6, LiTFSI, and LiBETI have been recorded and analyzed by means of density functional theory (DFT) calculations, with good agreement between experimental and calculated spectra. The results of this study are used to characterize electrode/electrolyte interfaces of graphite negative electrodes in Li-ion batteries using organic carbonate electrolytes containing LiTFSI or LiBETI salts. By a combined X-ray photoelectron spectroscopy (XPS) core peaks/valence analysis, we identify the main constituents of the interface. Differences in the surface layers' composition can be evidenced, depending on whether LiTFSI or LiBETI is used as the lithium salt.

Journal Article↗

PubMed2006

Characterization of osteoprotegerin binding to glycosaminoglycans by surface plasmon resonance: role in the interactions with receptor activator of nuclear factor kappaB ligand (RANKL) and RANK.

Osteoprotegerin (OPG) is a decoy receptor for receptor activator of nuclear factor kappaB ligand (RANKL), a key inducer of osteoclastogenesis via its receptor RANK. We previously showed that RANK, RANKL, and OPG are able to form a tertiary complex and that OPG must be also considered as a direct effector of osteoclast functions. As OPG contains a heparin-binding domain, the present study investigated the interactions between OPG and glycosaminoglycans (GAGs) by surface plasmon resonance and their involvement in the OPG functions. Kinetic data demonstrated that OPG binds to heparin with a high-affinity (KD: 0.28 nM) and that the pre-incubation of OPG with heparin inhibits in a dose-dependent manner the OPG binding to the complex RANK-RANKL. GAGs from different structure/origin (heparan sulfate, dermatan sulfate, and chondroitin sulfate) exert similar activity on OPG binding. The contribution of the sulfation pattern and the size of the oligosaccharide were determined in this inhibitory mechanism. The results demonstrated that sulfation is essential in the OPG-blocking function of GAGs since a totally desulfated heparin loses its capacity to bind and to block OPG binding to RANKL. Moreover, a decasaccharide is the minimal structure that totally inhibits the OPG binding to the complex RANK-RANKL. Western blot analysis performed in 293 cells surexpressing RANKL revealed that the pre-incubation of OPG with these GAGs strongly inhibits the OPG-induced decrease of membrane RANKL half-life. These data support an essential function of the related glycosaminoglycans heparin and heparan sulfate in the activity of the triad RANK-RANKL-OPG.

Binding, Competitive↗

PubMed2006

Health status in patients with Alzheimer's disease: an investigation of inter-rater agreement.

OBJECTIVE: The purpose of the present study was to examine the level of agreement between health status ratings provided by patients with Alzheimer's disease and by their proxies. BACKGROUND: Because proxy-completed responses are often necessary in assessing health outcomes for the elderly, it is necessary to determine the feasibility and potential limitations of using proxies as a patient substitutes. METHODS: To assess the potential utility of proxy responses on health status when subjects present a cognitive impairment, this study compared the responses of 70 subjects with Alzheimer's disease and those of their family and/or care provider proxy using the SF-36. Agreement between proxies and patients was measured by intraclass correlation coefficients (ICCs). RESULTS: The proportion of exact agreement between patients and proxies on the 36 items ranged from 3.3 to 41.7%. Results reveal poor to moderate agreement between patient and proxy reports. Proxy reliability varied according to the relationship of the proxy to the index subject. Agreement decreased significantly with increasing severity of dementia and with increasing severity of Physical status (Katz ADL). Agreement was better for measures of functions that are directly observable and relatively poor for more subjective measures. CONCLUSIONS: Our results confirm the importance of the information source used for patient health status.

Aged↗

PubMed2006

Molecular profiling of bladder tumors based on the detection of FGFR3 and TP53 mutations.

PURPOSE: On a routine basis we performed systematic molecular screening for FGFR3 and TP53 mutations in 121 bladder tumors. We then specifically analyzed the predictive value of the recurrence of FGFR3 and TP53 genotypes in superficial lesions. MATERIALS AND METHODS: The FGFR3 gene was analyzed by direct sequencing of exons 7, 10 and 15, whereas TP53 status was determined using the p53 functional assay in yeast. RESULTS: We identified a missense FGFR3 mutation in 66% of pTa, 26% of pT1 and 12% of pT2 tumors. Of activating FGFR3 mutations 54% and 85% were found in low G1 and intermediate G2 grade tumors, respectively, but in only 20% of high grade G3 tumors. We detected inactivating TP53 mutations in 10% of pTa, 42% of pT1 and 58% of pT2 tumors. Moreover, TP53 mutations were found only in 23% of grade G1 and 3% of grade G2 tumors but in 44% of high grade G3 tumors. When the 2 genotypes were combined, we observed that 58% of pTa tumors had the (mutant FGFR3, WT TP53) genotype, whereas 58% of invasive lesions harbored the inverse genotype (WT FGFR3, mutant TP53). The (mutant FGFR3, WT TP53) genotype and the (WT FGFR3, mutant TP53) genotype were detected in 23% and 38% of pT1G3 tumors, respectively. In the subgroup of 92 patients with superficial pTa-T1 bladder tumors we did not find that the TP53 or FGFR3 genotype alone or combined had a predictive value for tumor recurrence. CONCLUSIONS: Our data again represent solid proof for the pivotal role of FGFR3 and TP53 mutations in superficial and invasive bladder tumors, respectively. However, other molecular markers should be identified for borderline pT1G3 bladder tumors, which are probably at the crossroads of these 2 distinct molecular pathways.

Aged↗

PubMed2005

[Consensus statement on severe dementia].

Under the auspices of the French Society of Gerontology and Geriatrics, a multidisciplinary group of experts, including geriatricians, neurologists, epidemiologists, psychiatrists, pharmacologists, and public health specialists developed consensus recommendations about care for patients with severe dementia. They defined 21 recommendations for general practitioners, long-term care physicians, and specialists, based on the knowledge currently available (2005). The aim of care at all stages is to mitigate the quality-of-life of patient, caregiver, and family insofar as possible, combining care and future planning until the end of life. Management, to take into account problems including nutritional status, behavior disorders, and ability (or inability) to perform activities of daily living, must be global, multidisciplinary, and coordinated and must optimize use of local medical and social resources. The group also stressed the importance of clinical research to improve knowledge of disease course and assess management strategies and recommended specific area for research.

Aged↗

PubMed2005

Intracellular nucleotide and nucleotide sugar contents of cultured CHO cells determined by a fast, sensitive, and high-resolution ion-pair RP-HPLC.

Analysis of intracellular nucleotide and nucleotide sugar contents is essential in studying protein glycosylation of mammalian cells. Nucleotides and nucleotide sugars are the donor substrates of glycosyltransferases, and nucleotides are involved in cellular energy metabolism and its regulation. A sensitive and reproducible ion-pair reverse-phase high-performance liquid chromatography (RP-HPLC) method has been developed, allowing the direct and simultaneous detection and quantification of some essential nucleotides and nucleotide sugars. After a perchloric acid extraction, 13 molecules (8 nucleotides and 5 nucleotide sugars) were separated, including activated sugars such as UDP-glucose, UDP-galactose, GDP-mannose, UDP-N-acetylglucosamine, and UDP-N-acetylgalactosamine. To validate the analytical parameters, the reproducibility, linearity of calibration curves, detection limits, and recovery were evaluated for standard mixtures and cell extracts. The developed method is capable of resolving picomolar quantities of nucleotides and nucleotide sugars in a single chromatographic run. The HPLC method was then applied to quantify intracellular levels of nucleotides and nucleotide sugars of Chinese hamster ovary (CHO) cells cultivated in a bioreactor batch process. Evolutions of the titers of nucleotides and nucleotide sugars during the batch process are discussed.

Animals↗

PubMed2005

Enhanced tumor regression and tissue repair when zoledronic acid is combined with ifosfamide in rat osteosarcoma.

The efficacy of zoledronic acid (ZOL), with or without the anticancer drug ifosfamide (IFO), was tested on primary bone tumor growth using a rat-transplantable model of osteosarcoma. The effects on bone remodeling and tumor growth were analyzed by radiography, micro-computed tomography (micro-CT), and histological staining. The in vitro effects of ZOL were studied by proliferation, apoptosis, and cell cycle analyses on the osteosarcoma cells OSRGA compared to rat primary osteoblasts. Treatment with ZOL was effective in preventing the formation of osteolytic lesions that developed in bone sites and in reducing the local tumor growth, as compared to the untreated rats. The combination of ZOL and IFO was more effective than each agent alone in preventing tumor recurrence, improving tissue repair, and increasing bone formation as revealed by the analysis of trabecular architecture. In vitro studies demonstrated that ZOL was more potent against the OSRGA cell line than osteoblasts (with a half-maximal inhibitory effect on proliferation seen at 0.2 and 20 microM, respectively), the ZOL-induced inhibition of OSRGA proliferation being due to cell cycle arrest in S-phase. No effect on OSRGA apoptosis could be observed in vitro, as assessed by Hoechst staining and caspase-1 and -3 activation. In situ cell death was determined by TUNEL staining on tumor tissue sections. No significant difference in TUNEL-positive cells could be observed between ZOL-treated and -untreated rats. This is the first report of the anti-bone resorption and antitumoral activities of zoledronic acid in a rat model of osteosarcoma, and its beneficial association with an antitumoral chemotherapeutic drug in preventing tumor recurrence.

Animals↗

PubMed2005

[Consensus statement on severe dementia].

Under the auspices of the French Society of Gerontology and Geriatrics, a multidisciplinary team including geriatritians, neurologists, epidemiologists, psychiatrists, pharmacologists and public health specialists developed a consensus on care for patients with severe dementia. They defined 21 recommendations for general practitioners, long-term care physicians and specialists based on knowledge available in 2005. At all stages of the disease, the objective of care is to improve as much as possible quality-of-life for the patient and his/her family, including a life project until the end of life. It is always possible to do something for these patients and their family: nutritional status, behavior disorders, and incapacities to deal with basic activities of daily life have to be taken in consideration. Resource allocation and proximity care have to be targeted. Research areas necessary to improve the care of patients with severe dementia has been selected.

Aged↗

PubMed2005

Determination of 3-chloropropane-1,2-diol as its 1,3-dioxolane derivative at the microg kg-1 level: application to a wide range of foods.

This paper reports the application of a GC/MS method for the quantification of 3-chloropropane-1,2-diol (3-MCPD) at low microg kg-1 levels through the determination of its 1,3-dioxolane derivative to a wide range of foodstuffs. The proposed protocol is based on the methods generally performed in control laboratories. The two main stages of the method - the solid-phase extraction and the purification of the derivatives - have been optimized. The within-laboratory reproducibility meets the official performance criteria for verifying 3-MCPD at the 20 microg kg(-1) limit stipulated by the European Community for soy sauce. The limit of quantification was below 5 microg kg(-1) for all the foodstuffs analysed. This method offers a valuable alternative to the draft CEN European Standard: instead of diethyl ether, much safer ethyl acetate is used; derivatization is more selective; and reagents are common stable chemicals. This method was successfully applied to toasted bread, savoury crackers, cheese, soups, including vegetable-based soups, meat products such as salami, vegetable oils, sauces, soy sauce and related products. Upon checking the method performance in the case of vegetable oils, the unexpected presence of monobromopropanediols was detected.

Bread↗

PubMed2004

RANKL/RANK/OPG: new therapeutic targets in bone tumours and associated osteolysis.

The emergence of the molecular triad osteoprotegerin (OPG)/Receptor Activator of NF-kB (RANK)/RANK Ligand (RANKL) has helped elucidate a key signalling pathway between stromal cells and osteoclasts. The interaction between RANK and RANKL plays a critical role in promoting osteoclast differentiation and activation leading to bone resorption. OPG is a soluble decoy receptor for RANKL that blocks osteoclast formation by inhibiting RANKL binding to RANK. The OPG/RANK/RANKL system has been shown to be abnormally regulated in several malignant osteolytic pathologies such as multiple myeloma [MM, where enhanced RANKL expression (directly by tumour cells or indirectly by stromal bone cells or T-lymphocytes)] plays an important role in associated bone destruction. By contrast, production of its endogenous counteracting decoy receptor OPG is either inhibited or too low to compensate for the increase in RANKL production. Therefore, targeting the OPG/RANK/RANKL axis may offer a novel therapeutic approach to malignant osteolytic pathologies. In animal models, OPG or soluble RANK was shown both to control hypercalcaemia of malignancy and the establishment and progression of osteolytic metastases caused by various malignant tumours. To this day, only one phase I study has been performed using a recombinant OPG construct that suppressed bone resorption in patients with multiple myeloma or breast carcinoma with radiologically confirmed bone lesions. RANK-Fc also exhibits promising therapeutic effects, as revealed in animal models of prostate cancer and multiple myeloma. If the animal results translate to similar clinical benefits in humans, using RANK-Fc or OPG may yield novel and potent strategies for treating patients with established or imminent malignant bone diseases and where standard therapeutic regimens have failed.

Antineoplastic Agents↗

PubMed2004

Cellular activity and signaling induced by osteoprotegerin in osteoclasts: involvement of receptor activator of nuclear factor kappaB ligand and MAPK.

Osteoprotegerin (OPG) is a decoy receptor for receptor activator of nuclear factor kappaB ligand (RANKL), an inducer of osteoclastogenesis via its receptor RANK. We recently demonstrated that OPG also exerts a direct effect in osteoclasts by regulating protease expression. Herein, we showed that OPG-induced pro-matrix metalloproteinase-9 activity was abolished by ras/MAPK inhibitors in purified osteoclasts. OPG induced the phosphorylation of p38 and ERK1/2 in RAW264.7 cells. Only p38 activation was totally abolished by a blocking anti-RANKL antibody or an excess of RANKL. Surface plasmon resonance experiments revealed that RANK, RANKL and OPG are able to form a tertiary complex. These results suggested a potential formation of a tertiary complex RANK-RANKL-OPG on osteoclasts. Thus, OPG is not only a soluble decoy receptor for RANKL but must be also considered as a direct effector of osteoclast functions.

Animals↗

PubMed2004

Applicability of predictive models to the peptide mobility analysis by capillary electrophoresis-electrospray mass spectrometry.

The prediction of peptide mobility by capillary electrophoresis (CE) coupled to electrospray mass spectrometry (MS) is studied in order to verify the validity of the semi-empirical models developed in classical CE. This work relies on the experimental determination of the electrophoretic mobilities of 68 peptides, different in charge and in size. The results indicate that the prediction is possible in CE-MS experiments, in spite of the restraints inherent in the coupling conditions. The best fit of experimental data was obtained with the Offord's model. The efficiency of the model was confirmed by the analysis of a peptide mixture in CE-MS.

Amino Acid Sequence↗

PubMed2004

Agreement between dementia patient report and proxy reports using the Nottingham Health Profile.

OBJECTIVE: The aim of the study was to examine the agreement between patient reports and their proxy reports (family and care provider proxies) on Health Status in a sample of patients with dementia. METHOD: Ninety-nine patients with mild to moderate dementia and proxies completed the 38-item Nottingham Health Profile (NHP) questionnaire. RESULTS: Completion rates for the different NHP dimensions ranged from 78 to 90% for the dementia subjects. Inter-rater agreement between different proxies and subject was from moderate to good for physical assessment (ICCs from 0.54 to 0.78 for physical mobility scales). Patient/family proxy concordance was moderate to good for five out of six dimensions (physical mobility, social isolation, pain, energy, sleep) and poor for emotional reaction. Family proxies systematically reported lower functioning than did patients in the four subscales assessing: physical mobility (p <0.0001), energy (p <0.005), social isolation (p <0.01) and sleep (p <0.03). Care provider proxies only estimated physical mobility as lower (p <0.0001). CONCLUSION: Age and physical status of the patient significantly affected agreement in patient-care provider proxy ratings. Thus, caution is appropriate when resorting to proxies to estimate the Health Status of a dementia patient.

Aged↗

PubMed2003

Use of the EQ-5D among patients suffering from dementia.

BACKGROUND AND OBJECTIVE: This study was designed to determine the acceptability, feasibility, reliability, and validity of the French version of EQ-5D measuring HRQol in subjects with dementia. METHODS: EQ-5D was administered to 142 subjects. The feasibility and acceptability were determined by the refusal rate, the type of administration, and the percentage and distribution of missing data. Test-retest reliability was studied by kappa coefficients and validity by agreement between subjects' and proxies' assessments. RESULTS: The response rate was satisfactory. The instrument discriminated well among the subjects. Test-retest reliability was average. The validity was poor if we consider the agreement between patients' and caregivers' reports, but other criteria of validity produced better results. Subjects' responses on each dimension were related with their global judgment of health in the expected direction. Significant relations were found between the Katz index of ADL and self-rated difficulties only for expected dimensions. Relations with age and with gender were in line with expectations. CONCLUSION: Results led to consider that patients' responses are not entirely devoid of judgment. It seems that dementia patients are capable of expressing their health-related quality of life through a brief instrument as the EQ-5D.

Aged↗

PubMed2003

Implicit memory for words presented in short texts is preserved in Alzheimer's disease.

BACKGROUND: The level of efficiency of implicit memory in Alzheimer's disease remains unclear as previous studies using stem completion tasks have led to contradictory results. METHOD: The present study used target words embedded in significant short texts that subjects were required to read aloud (i.e. to enhance semantic processing). Texts were presented in two perceptual situations: 'simple' (blank spaces delimitating words) and complex' (spaces were filled by '8's). In the completion phase, patients had to write the first word that came to mind in order to complete a three-letter stem. The recognition phase explored explicit memory performance. The performance of 24 Alzheimer patients was compared to a matched sample of healthy controls. RESULTS: Reading times differed between groups and were shorter for healthy controls. Recognition was dramatically lower in patients, thus confirming the alteration of explicit memory in this pathology. However, a significant priming effect (e.g. the tendency to complete the stem with the aid of a previously explored word) was present in both groups and did not differ between patients and healthy controls. CONCLUSIONS: The absence of a correlation between priming and recognition scores suggests that this result cannot be explained by an explicit memory bias. Moreover, as the priming level was identical whatever the perceptual aspect of the text, we suggest that the priming effect is not only mediated by perceptual processes but also by lexical and conceptual processes, which to some extent are preserved during the light and moderate stages of this disease.

Aged↗

PubMed2002

Leukaemia inhibitory factor (lif) is expressed in hypertrophic chondrocytes and vascular sprouts during osteogenesis.

Avascular cartilage is replaced by highly vascularized bone tissue during endochondral ossification, a process involving capillary invasion of calcified hypertrophic cartilage in association with apoptosis of hypertrophic chondrocytes, degradation of cartilage matrix and deposition of bone matrix. All of these events are closely controlled, especially by cytokines and growth factors. Leukaemia inhibitory factor (LIF), a member of the gp130 cytokine family, is involved in osteoarticular tissue metabolism and might participate in osteogenesis. Immunohistochemical staining showed that LIF is expressed in hypertrophic chondrocytes and vascular sprouts of cartilage and bone during rat and human osteogenesis. LIF is also present in osteoblasts but not in osteoclasts. Observations in a rat endochondral ossification model were confirmed by studies of human cartilage biopsies from foetuses with osteogenesis imperfecta. LIF was never detected in adult articular chondrocytes and bone-marrow mesenchymal cells. These results and other data in the literature suggest that LIF is involved in the delicate balance between the rate of formation of calcified cartilage and its vascularization for bone development.

Animals↗