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Biomedical subjects

C Dionne

Publications and source records attributed to C Dionne.

At least 19 recordsLinked to original sources
PubMed2001

Effect of CEP-751 (KT-6587) on neuroblastoma xenografts expressing TrkB.

BACKGROUND: The compound CEP-751 (KT-6587), a potent and selective inhibitor of the Trk family of tyrosine kinases, has been shown to inhibit the growth of human neuroblastoma (NB) xenografts in nude mice [1]. PROCEDURE: To address its mechanism of action, we studied SY5Y, a human NB cell line with no detectable Trk expression, and two subclones transfected with TrkB. The transfected clones, SY5Y (G8) and SY5Y (G12), expressed moderate and high levels, respectively, of TrkB mRNA and protein. These TrkB-expressing subclones and the parental line were then grown as xenografts in nude mice, and CEP-751 was used to inhibit TrkB tyrosine kinase activity in these xenografts. Animals were treated twice a day with CEP-751 (21 mg/kg), or with the carrier vehicle as a control. TrkB expression in the resultant tumors was examined by quantitative RT-PCR. The effect of CEP-751 on TrkB activation by BDNF was examined in G12 cells in culture by immunoprecipitation with antipan Trk antiserum, followed by Western blot analysis using antiphosphotyrosine antibodies. To determine if CEP-751 was causing apoptosis, the TUNEL assay was used. RESULTS: CEP-751 had little effect on the growth of SY5Y tumors, but did slow the growth rate of the C8 and G12 tumors. The daily growth rate of the treated tumors was 0.16, 0.13, and 0.10 cm3, respectively, for the SY5Y, G8, and G12 tumors. RT PCR analysis confirmed the expression of TrkB in G8 and G12, but not in SY5Y tumors. Activation of TrkB by BDNF in G12 cells was inhibited by CEP-751 in a dose dependent fashion. The treated tumors showed marked evidence of apoptosis. CONCLUSIONS: These data suggest that the effect of CEP-751 is due, at least in part, to its inhibition of TrkB kinase, and that CEP-751 may become a useful therapeutic tool for the treatment of aggressive neuroblastomas, which often express TrkB.

Animals↗
PubMed2000

[Validation of a measurement instrument to evaluate computer access in people with physical disabilities].

The aim of this study was to develop an instrument to measure performance in computer tasks for persons with physical impairments. The objectives were to assure the content validity and the internal consistency of the test as well as the reliability of each task. The first step was to determine the mouse and keyboard actions necessary to use a computer. Resulting from these actions, 15 standardized computer tasks were designed as part of the test. To measure reliability and internal consistency, the test was administered twice to 19 persons without disabilities and 17 persons with disabilities. Reliability was established for most of the tasks and the test showed good internal consistency. This instrument could contribute to the improvement of occupational therapy interventions regarding computer access.

Adolescent↗
PubMed1995

Formal education and back-related disability. In search of an explanation.

STUDY DESIGN: The present study is a 2-year prospective study with repeated measurements. OBJECTIVES: To examine the association of education with back-related disability along with four sets of variables that might explain this relationship: clinical, behavioral, and environmental factors; occupational variables; health care use; and interactions between stressful events and coping strategies. SUMMARY OF BACKGROUND DATA: Although education has been found to be associated with back-related disability in previous reports, this relationship remains to be explained. Examination of this association may yield a better understanding of the causes and natural history of disability resulting from back pain. METHODS: Subjects were 1213 enrollees of a Health Maintenance Organization (HMO) who consulted a primary care physician for back pain in 1989-1990, completed a baseline telephone interview, and had a follow-up evaluation after 1 and 2 years, using a modified version of the Roland-Morris Scale to measure disability. RESULTS: Subjects who completed 13 years or more of schooling had less disability and a greater decline in their disability over time than those who completed less schooling. Occupational characteristics and somatization were among the strongest explanatory factors. Cigarette smoking contributed to the explanation of the cross-sectional association. CONCLUSIONS: Education is associated cross-sectionally and longitudinally with disability resulting from back pain. A wide range of variables may mediate the education-back-related disability association, including a propensity to report diffuse physical symptoms (somatization), lifestyle (e.g., cigarette smoking), and occupational factors.

Adult↗
PubMed1995

Expression of a Trk high affinity nerve growth factor receptor in the human prostate.

Nerve growth factor-beta (NGF beta) and a NGF beta-immunoreactive protein derived from human prostatic stromal cell secretory protein (hPS) have been shown to stimulate the growth of prostate epithelial cells. An NGF beta-immunoreactive protein has been localized to the stroma of human prostate tissues, and a low affinity NGF receptor (gp75NGFR) has been localized to the adjacent epithelia, consistent with the paracrine regulation of prostate growth. Interestingly, gp75NGFR is progressively lost during neoplastic progression of the human prostate. In this report we have characterized the expression of the signal-transducing component of the NGF receptor, the Trk tyrosine receptor kinase, in prostate epithelial cells that bind exogenous NGF beta and an endogenous NGF beta-immunoreactive protein in hPS. In this context, a pan-Trk antibody that recognizes all of the members of the Trk receptor family (TrkA, TrkB, and TrkC) specifically localized expression of the Trk receptor to the epithelial component of normal prostate tissue, benign prostatic hyperplasia, and adenocarcinoma tissue. The binding of [125I]NGF beta to the surface of primary cultures of human prostate epithelia and the TSU-pr1 human metastatic prostate tumor cell line was displaced with either excess cold NGF beta or hPS, whereas binding was not displaced by epidermal growth factor or platelet-derived growth factor. Scatchard plot analysis of [125I]NGF beta binding to these cells identified a low affinity binding site (Kd = 1.9 x 10(-9) M) and a high affinity binding site (Kd = 1.8 x 10(-11) M) on the primary prostate epithelia, whereas only a high affinity binding site (Kd = 1.3 x 10(-11) M) was observed on the TSU-pr1 tumor cells. Stimulation of TSU-pr1 cells with either NGF beta or hPS induced tyrosine phosphorylation of Trk proteins, whereas no phosphorylation was evident in untreated cells, cells treated with hPS immunoprecipitated with anti-NGF beta antibody, or brain-derived neurotrophic factor- and neurotrophin-3-treated cells. The Trk protein was also observed in these cells by immunoblot analysis with pan-Trk antibody. These results demonstrate a functional Trk receptor in the epithelia of the human prostate that is responsive to exogenous NGF beta and an endogenous NGF beta-immunoreactive protein in hPS, thereby supporting the concept of the paracrine regulation of growth in the human prostate via a stromal neurotrophin-epithelial Trk receptor interaction.

Binding, Competitive↗
PubMed1994

Postnatal expression of nerve growth factor receptors in the rat testis.

Because nerve growth factor beta (NGF beta) and its corresponding receptors have been implicated in the paracrine regulation of spermatogenesis, we examined the postnatal developmental expression of the low- and high-affinity NGF receptors in the rat testis, and localized their expression to specific testicular cell types. The neurotropin receptors consist of a low-affinity p75 nerve growth factor receptor (LNGFR) and a family of high-affinity tyrosine receptor kinases (trk). Both the p75 LNGFR gene product and the trk receptor gene product were detected in immature rat testes, with maximal expression in 10- and 20-day-old rats. Expression of the testicular p75 LNGFR and the trk receptor progressively declined in older animals so that they were barely detectable in 90-day-old adult rats. The 75-kDa LNGFR was detected in membrane fractions of Sertoli cells, whereas the p75 LNGFR was not detected by Western blot in membrane fractions of round spermatids and primary spermatocytes. Interestingly, microsomal fractions of peritubular myoid cells were immunoreactive for a 65-kDa band on Western blots with the p75 LNGFR monoclonal antibody. Immunoblot analysis of the trk receptor in cell lysates of isolated cell types was inconclusive. Excess NGF beta and round spermatid protein, which is known to contain a NGF-like protein, were both capable of displacing the binding of 125I-NGF beta from the surface of Sertoli cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Genealogy and regional distribution of lipoprotein lipase deficiency in French-Canadians of Quebec.

Lipoprotein lipase (LPL) deficiency, an autosomal recessive disorder causing chylomicronemia, has a high prevalence in the French-Canadian population of Quebec. The molecular basis of LPL deficiency has been defined, and two major mutations have been shown to have an uneven geographic distribution. Two mutations, one at residue 188 (M-188) and the other at residue 207 (M-207), are described here; they account for 95% of the mutant alleles. The carrier rate of M-188 was highest in western Quebec (1/326) but that of M-207 was much higher in the eastern part of the province (1/85). Genealogical reconstruction has revealed that both mutations were introduced to the French-Canadian population by migrants from France in the seventeenth century. M-188 is likely to have a Scottish ancestor, whereas M-207 appears to be of French origin.

France↗
PubMed1992

Geographic distribution and genealogy of mutation 207 of the lipoprotein lipase gene in the French Canadian population of Québec.

Mutations in the lipoprotein lipase (LPL) gene, leading to partial or total inactivation of the enzyme, result in a hereditary clinical syndrome called familial LPL deficiency. The French Canadian population, which is primarily and historically located in the province of Québec, has the highest worldwide frequency of LPL-deficient patients. We have analyzed the prevalence, spatial distribution, and genealogy in the Québec population of a LPL gene mutation, M-207 (P207L in conventional notation), which changes the amino acid proline to leucine in position 207 of the LPL protein and inactivates the enzyme. Our results show that M-207 is the most prevalent LPL gene mutation among French Canadians and accounts for the largest proportion of LPL-deficient patients in this population. Genealogical reconstruction of French Canadian LPL-deficient patients point to 16 founders of M-207, all of whom migrated to Québec in the early seventeenth century from the north-western part of France, especially from the region of Perche. Most of the carriers of M-207 are, at present, found in Charlevoix, Saguenay-Lac-St-Jean regions of eastern Québec. On the basis of the number of homozygote M-207 LPL-deficient patients so far identified, we estimate that there are at least 31,000 carriers of this mutation in the province of Québec. This constitutes a large pool of individuals at risk for atherosclerosis and other lipid-related diseases, since LPL deficiency is considered to be a significant contributing factor in the etiology and development of these diseases.

Alleles↗
PubMed1992

Prevalence, geographical distribution and genealogical investigations of mutation 188 of lipoprotein lipase gene in the French Canadian population of Québec.

Familial lipoprotein lipase deficiency (FLD) is of particular interest to the French Canadian population of Québec since the largest concentration of homozygotes and carriers of this genetic disease in the world resides in this area. We have previously described a missense mutation (M-188) in the lipoprotein lipase (LPL) gene which was present in FLD patients belonging to different ancestries, including a number of French Canadians (Monsalve MV et al. J Clin Invest 1990: 86: 728-734). In the present report, we show that this mutation, although found in largest absolute numbers among French Canadians as compared to other groups in the world, accounts for only a small proportion (24%) of all the LPL mutant alleles in this population. The M-188 occurs either in the homozygote state or as a compound heterozygote with another LPL mutation. Analysis of geographic distribution indicates that the M-188 is more prevalent in western Québec, with the highest carrier rate in the Mauricie region. Genealogical reconstruction leads to the recognition of four founders for M-188, all emigrants from France to Québec in the 17th century.

Base Sequence↗
PubMed1992

Genetic epidemiology of lipoprotein lipase deficiency in Saguenay-Lac-St-Jean (Québec, Canada).

Familial hyperchylomicronemia due to the lipoprotein lipase (LPL) activity deficiency (Type I hyperlipoproteinemia) is an autosomal recessive disorder with a prevalence estimated at one case per million. Thirty-four type I individuals are known in Saguenay-Lac-St-Jean (SLSJ), a geographically isolated region of Quebec. The prevalence of type I and LPL deficient heterozygote in this region was estimated at 1/6382 and 1/46 inhabitants respectively. The mean inbreeding coefficient was slightly elevated in the type I group compared with three control groups. The mean kinship coefficient was 15.1 times higher in the type I group than in the control groups. The high prevalence of type I in SLSJ appears to be the result of the emigration of carriers of LPL deficiency from Charlevoix, another isolated region of quebec to the SLSJ region. Endogamy also played a crucial role in increasing the prevalence of type I in SLSJ.

Child↗
PubMed1991

Founder effect in familial hyperchylomicronemia among French Canadians of Quebec.

Familial hyperchylomicronemia has reached a high prevalence in the French Canadian population of eastern Quebec. The birth places of 58 carriers identified through the birth of one affected child clustered in three regions. The genealogies of these 58 individuals showed that no founder was common to all of them. Three sets of founders were found, one for each region, with little overlapping between two regions. These results strongly suggest that more than one mutation, introduced by the French migrants in the 17th century, are segregating in the French Canadian population. Perche, a region situated between Paris and Normandy, appeared to be the most likely putative center of diffusion of at least one mutation in the lipoprotein lipase gene segregating in the modern-day French Canadian population of Quebec.

France↗
PubMed1991

The mRNAs encoding acidic FGF, basic FGF and FGF receptor are coordinately downregulated during myogenic differentiation.

Acidic and basic fibroblast growth factors (FGFs) are members of a family of proteins that exert pleiotropic effects in a range of cell types including skeletal myocytes. Previous studies demonstrate that exogenously supplied FGFs stimulate proliferation of myoblasts and inhibit their differentiation in culture, but little information is available concerning endogenous expression of FGFs by skeletal myocytes. In this study acidic and basic FGF mRNAs were found to be expressed in murine and rat skeletal muscle, and expression was demonstrated to vary with the tissue and species examined. Myogenic cell lines were then analyzed to determine if FGFs are expressed in myoblasts, and if so, whether expression is regulated during myogenic differentiation. Murine Sol 8 and rat L6 myoblasts were found to express acidic and basic FGF mRNAs, and the expression of both growth factors was downregulated at the transcriptional level during myogenic differentiation. A decrease in expression of the mouse homologue of the human FGF receptor paralleled the decrease in acidic and basic FGF mRNAs in Sol 8 cells, indicating that the decrease in FGF receptor abundance previously observed during myogenic differentiation is regulated at the mRNA level. The results of this study suggest that a coordinate decrease in endogenously produced acidic and basic FGFs and their cognate receptor may participate in the regulation of myogenic differentiation. Furthermore, the observation that expression of a myogenic determination gene, myogenin, increases as FGF transcripts decline, together with previous data demonstrating suppression of myogenin expression by FGF, suggest a mechanism whereby endogenously produced FGFs may exert their effect on differentiation.

Animals↗
PubMed1989

Receptor for acidic fibroblast growth factor is related to the tyrosine kinase encoded by the fms-like gene (FLG).

We have previously isolated a human gene from an endothelial cell cDNA library encoding a putative tyrosine kinase; we have designated this gene the fms-like gene (FLG). To analyze the gene product(s) of FLG, we have generated rabbit polyclonal antibodies directed against a synthetic peptide from FLG and used it to immunoprecipitate biosynthetically labeled FLG protein from a variety of human cell lines. These antibodies specifically recognized glycoprotein(s) of 100, 120, and 135 kDa with protein cores of 90 and 110 kDa. Acidic fibroblast growth factor (aFGF) stimulated tyrosine kinase activity of FLG in vitro and in living cells, suggesting that FLG encodes the membrane receptor for aFGF. Further supporting evidence came from cross-linking experiments on intact cells with the covalent cross-linking agent disuccinimidyl suberate and 125I-labeled aFGF as a specific probe. The cross-linked 125I-labeled aFGF-aFGF receptor complex was specifically immunoprecipitated with FLG antipeptide antibodies. It appears, therefore, that the receptor(s) for aFGF is related to the FLG gene product.

Animals↗
PubMed1984

The distance between S1, S21, and the 3' end of 16S RNA in 30S ribosomal subunits. The effect of poly(uridylic acid) and 50S subunits on these distances.

The apparent distances between probes covalently attached to the cysteine thiols of S1 or S21 and the 3' end of 16S RNA in Escherichia coli 30S ribosomal subunits were determined by non-radiative energy transfer to be: S21-16S RNA, 5.1 nm; S21-S1, 6.9 nm; S1-16S RNA, 6.8 nm. Binding of poly(uridylic acid) to 30S subunits causes the apparent distances between S1 and 16S RNA or S21 and 16S RNA to increase by more than 1.2 nm and 0.5 nm, respectively, but has little or no effect on the S1-S21 distance. Binding of 50S subunits causes an apparent increase in the S21-16S RNA and S21-S1 distances by 1.0 nm and 0.8 nm, respectively, but has little or no effect on the S1-16S-RNA distance.

Coumarins↗