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Biomedical subjects

G Raymond

Publications and source records attributed to G Raymond.

At least 19 recordsLinked to original sources
PubMed2006

Effects of two medicinal plants Psidium guajava L. (Myrtaceae) and Diospyros mespiliformis L. (Ebenaceae) leaf extracts on rat skeletal muscle cells in primary culture.

Crude decoction, aqueous and ethanolic extracts of two medicinal plants (Psidium guajava and Diospyros mespiliformis), widely used in the central plateau of Burkina Faso to treat many diseases were evaluated for their antagonistic effects on caffeine induced calcium release from sarcoplasmic reticulum of rat skeletal muscle cells. These different extracts showed a decrease of caffeine induced calcium release in a dose dependent manner. Comparison of the results showed that Psidium guajava leaf extracts are more active than extracts of Diospyros mespiliformis and that crude decoctions show better inhibitory activity. The observed results could explain their use as antihypertensive and antidiarrhoeal agents in traditional medicine, by inhibiting intracellular calcium release.

Animals↗
PubMed2005

Regulation of store-operated calcium entries and mitochondrial uptake by minidystrophin expression in cultured myotubes.

Defective expression of dystrophin in muscle cells is the primary feature of Duchenne muscular dystrophy (DMD), which is accompanied by fiber necrosis and intracellular calcium mishandling. These features led to the hypothesis that dystrophin could control calcium movements. Calcium mishandling in human DMD myotubes is dependent on contraction and/or calcium release activity, suggesting the involvement of channels being activated during these processes. Forced expression of minidystrophin at the plasma membrane of dystrophin-deficient Sol8 myotubes reactivates appropriate sarcolemmal expression of dystrophin-associated proteins and results in normal calcium homeostasis. In active dystrophic myotubes, store-operated calcium channels could be responsible for a sustained calcium influx in muscle cells. We show here that depletion of calcium stores (sarcoplasmic reticulum) by repetitive activation of calcium release and blockade of SERCA leads to a calcium influx. In myotubes expressing recombinant minidystrophin, these store-dependent influxes were reduced to a level similar to that observed in myotubes expressing native dystrophin. High store-dependent calcium influxes in dystrophin-deficient myotubes were associated with sustained cytosolic calcium transients and high intramitochondrial entries, while lower store-dependent calcium influx in myotubes expressing minidystrophin resulted in shorter calcium transients and reduced calcium uptake into mitochondria. We propose that minidystrophin negatively regulates sarcolemmal store-dependent calcium channels, which reduces store-dependent calcium influx, as well as its mitochondrial uptake. Forced expression of minidystrophin in dystrophic cells might restore the regulation of sarcolemmal store-dependent channels, which could protect against calcium mishandling.

Boron Compounds↗
PubMed2005

Novel glycosaminoglycan mimetic (RGTA, RGD120) contributes to enhance skeletal muscle satellite cell fusion by increasing intracellular Ca2+ and calpain activity.

Glycosaminoglycans (GAG) are classes of molecules that play an important role in cellular processes. The use of GAG mimetics called regenerating agent (RGTA) represents a tool to investigate the effect of GAG moiety on cellular behavior. A first member of the RGTA family (RG1192), a dextran polymers with defined amounts of sulfate, carboxymethyl, as well as hydrophobic groups (benzylamide), was shown to stimulate skeletal muscle repair after damage and myoblast differentiation. To obtain a comprehensive insight into the mechanism of action of GAG mimetics, we investigated the effect on myoblast differentiation of a novel RGTA, named RGD120, which was devoid of hydrophobic substitution and had ionic charge similar to heparin. Myoblasts isolated from adult rat skeletal muscles and grown in primary cultures were used in this study. We found that chronic treatment with RGD120 increased the growth of adult myoblasts and induced their precocious fusion into myotubes in vitro. It also partially overcame the inhibitory effect of the calpain inhibitor N-acetyl-leu-leu-norleucinal (ALLN) on these events. Western blot and zymography analyses revealed that milli calpain was slightly increased by RGD120 chronic treatment. In addition, using fluorescent probes (Indo-1 and Boc-leu-met-MAC), we demonstrated that RGD120 added to prefusing myoblast cultures accelerates myoblast fusion into myotubes, induced an increase of cytosolic free calcium concentration, and concomitantly an increase of intracellular calpain protease activity. Altogether, these results suggested that the efficiency of RGD120 in stimulating myogenesis might be in part explained through its effect on calcium mobilization as well as on the calpain amount and activity.

Animals↗
PubMed2005

Calcium sparks in muscle cells: interactive procedures for automatic detection and measurements on line-scan confocal images series.

In muscle cells, force development is controlled by Ca2+ ions, which are rapidly released from the sarcoplasmic reticulum (SR) during sarcolemmal depolarization. In addition to this synchronized spatially homogeneous calcium signal, localized quantal Ca2+ release events (sparks) have been recorded using laser scanning confocal fluorescence microscopy. Previously, algorithms without user intervention have been developed to automatically detect and analyse sparks on confocal line-scan (space-time: 512 x 512 pixels) single images. Here we present a computer program that we called "HARVest of Elementary Events" (HARVELE) developed to both analyse events on series of confocal images and follow sparks morphology from one site during several seconds. HARVELE, coded in the image-processing language IDL 5.3., can be applied on series of n images (512 x 512 x n) obtained from the same scanning line. Computing simultaneously entire series of images allows to measure, for each release site, the frequency and the morphology of release with the conventional amplitude, size, time and duration parameters defined for sparks analysis. The use of these procedures rapidly provides much information about the properties of calcium release sites in muscle cells population and can be applied on any elementary calcium events whatever the type of cell.

Animals↗
PubMed2005

Which biologic valve should we select for the 45- to 65-year-old age group requiring aortic valve replacement?

OBJECTIVE: The diversity of biologic valves available to replace the aortic valve renders selection difficult for the 45- to 65-year-old patient. To evaluate and compare the results of biologic valves in the 45- to 65-year-old patient, we reviewed our experience (1991-2004). METHODS: Three hundred thirty-two patients between 45 and 65 years old with isolated aortic valve disease had a biologic valve implanted: Freestyle valve in 140 patients, a homograft in 54 patients, a stented Mosaic or Perimount valve (stented xenograft) in 62 patients, and a Ross procedure in 76 patients. RESULTS: Perioperative mortality was comparable for all groups (Freestyle, 2.1%; homograft, 3.7%; stented xenograft, 3.2%; Ross procedure, 1.3%; P = .8). Echocardiographically determined valve performance at discharge was significantly enhanced in the Ross procedure and homograft groups (indexed effective orifice area: Freestyle, 0.9 +/- 0.3 cm 2 /m 2 ; homograft, 1.3 +/- 0.3 cm 2 /m 2 ; stented xenograft, 0.8 +/- 0.2 cm 2 /m 2 ; Ross procedure, 1.4 +/- 0.4; P < .0001; mean gradient: Freestyle, 12.0 +/- 6.6 mm Hg; homograft, 7.4 +/- 4.0 mm Hg; stented xenograft, 15.4 +/- 5.4 mm Hg; Ross procedure, 4.6 +/- 3.2 mm Hg; P < .0001). For all yearly follow-up, freedom from New York Heart Association class III or IV was comparable and greater than 95% for all groups. At 7 years, cardiac survival (homograft, 96.3% +/- 3.7%; Ross procedure, 90.6% +/- 6.3%; stented xenograft, 86.0% +/- 10.3%; Freestyle, 89.2% +/- 10.8%; P = .7) and freedom from reoperation (Ross procedure, 98.5% +/- 1.4%; homograft, 90.6% +/- 5.7%; Freestyle, 88.0% +/- 4.9%; stented xenograft, 90.0% +/- 8.0%; P = .4) were comparable. Freedoms from significant bleeding events, valve-related neurologic events, or endocarditis were comparable and greater than 95% for all groups. CONCLUSION: Type of aortic biologic valve for the 45- to 65-year-old patient does not affect midterm survival or valve-related morbidity. Thus the choice of biologic valve for the 45- to 65-year-old patient should be dictated by patient-surgeon preference, ease of implantation, and reoperation until longer comparative studies are available.

Age Factors↗
PubMed2004

Underreporting of vertebral fractures on routine chest radiography.

OBJECTIVE: Osteoporosis is underdiagnosed and therefore undertreated. We determined the potential usefulness of chest radiography for detecting clinically important vertebral fractures by performing semiquantitative reviews and quantitative digital morphometry on 100 routine chest radiographs taken in the emergency department and comparing the yield of these independent reviews with official radiology reports. MATERIALS AND METHODS: One hundred randomly selected chest radiographs of patients 60 years or older who presented to the emergency department of a tertiary care hospital were evaluated. Radiographs were selected without knowledge of the presenting complaint and were independently reviewed by two board-certified radiologists and a radiology resident. A validated semiquantitative method was used to assess lateral chest radiographs for vertebral fracture. In addition, quantitative digital morphometry was undertaken. A clinically important vertebral fracture was defined as one that was at least moderate to severe (loss of height >or=> 25%). RESULTS: Mean age of the population was 75 years, 47% were women, and 46% were admitted to the hospital. According to the reference radiologist, prevalence of moderate to severe vertebral fractures was 22%. Simple agreement was 87-88% among reviewers; kappa values were moderate (0.56-0.58). The greatest agreement was between the reference standard radiologist and quantitative digital morphometry (89% agreement; kappa = 0.67). Only 55% (12/22) of vertebral fractures we identified were mentioned in the official radiology reports. CONCLUSION: Chest radiography has potential as a screening tool for revealing previously undiagnosed vertebral fractures, although in this study only half of moderate to severe fractures that we identified were mentioned in official reports.

Aged↗
PubMed2002

Na+-Ca2+ exchange activity in rat skeletal myotubes: effect of lithium ions.

The whole-cell patch-clamp technique coupled with intracellular [Ca2+] measurements was used to investigate the sodium-calcium exchange mechanism in rat skeletal muscle cells in primary culture. Replacing external Na+ ions with Li+ or N-methyl-D-glucamine (NMDG+) ions generated outward currents which were correlated with significant increases of free cytosolic-calcium concentration. These results strongly argue for a functional Na+-Ca2+ exchange mechanism working in its reverse mode. Moreover, the outward currents were sensitive to the new compound KB-R7943 (10 microM), which has been shown to be a potent inhibitor of the sodium-calcium exchanger. Outward Na+-Ca2+ exchange current densities were reduced in the presence of external Li+ as compared to those measured in the presence of NMDG+. After replacing internal sodium by lithium ions, rapid changes of external lithium concentrations generated sarcolemmal currents which were accompanied by subsequent variations of intracellular calcium activity. The currents were dependent on extracellular Li+ with a half-maximal activation at 67 mM and a Hill coefficient of 2.9. This work shows that the Na+-Ca2+ exchanger is able to significantly influence the myoplasmic calcium concentration of cultured rat myotubes. On the other hand, our results suggest that Li+ ions may substitute Na+ ions to catalyse an electrogenic Li+/Ca2+ counter transport.

Animals↗
PubMed2001

Calcium currents and transients in co-cultured contracting normal and Duchenne muscular dystrophy human myotubes.

1. The goal of the present study was to investigate differences in calcium movements between normal and Duchenne muscular dystrophy (DMD) human contracting myotubes co-cultured with explants of rat spinal cord with attached dorsal root ganglia. Membrane potential, variations of intracellular calcium concentration and T- and L-type calcium currents were recorded. Further, a descriptive and quantitative study by electron microscopy of the ultrastructure of the co-cultures was carried out. 2. The resting membrane potential was slightly less negative in DMD (-61.4 +/- 1.1 mV) than in normal myotubes (-65.5 +/- 0.9 mV). Both types of myotube displayed spontaneous action potentials (mean firing frequency, 0.42 and 0.16 Hz, respectively), which triggered spontaneous calcium transients measured with Indo-1. 3. The time integral under the spontaneous Ca(2+) transients was significantly greater in DMD myotubes (97 +/- 8 nM s) than in normal myotubes (67 +/- 13 nM s). 4. The L- and T-type current densities estimated from patch-clamp recordings were smaller in DMD cells (2.0 +/- 0.5 and 0.90 +/- 0.19 pA pF(-1), respectively) than in normal cells (3.9 +/- 0.7 and 1.39 +/- 0.30 pA pF(-1), respectively). 5. The voltage-dependent inactivation relationships revealed a shift in the conditioning potential at which inactivation is half-maximal (V(h,0.5)) of the T- and L-type currents towards less negative potentials, from -72.1 +/- 0.7 and -53.7 +/- 1.5 mV in normal cells to -61.9 +/- 1.4 and -29.2 +/- 1.4 mV in DMD cells, respectively. 6. Both descriptive and quantitative studies by electron microscopy suggested a more advanced development of DMD myotubes as compared to normal ones. This conclusion was supported by the significantly larger capacitance of the DMD myotubes (408 +/- 45 pF) than of the normal myotubes (299 +/- 34 pF) of the same apparent size. 7. Taken together, these results show that differences in T- and L-type calcium currents between normal and DMD myotubes cannot simply explain all observed alterations in calcium homeostasis in DMD myotubes, thus suggesting that other transmembrane calcium transport mechanisms must also be altered in DMD myotubes compared with normal myotubes.

Animals↗
PubMed2001

Effects of Sclerocarya birrea (A. rich) hochst (anacardiaceae) leaf extracts on calcium signalling in cultured rat skeletal muscle cells.

Sclerocarya birrea is a plant used widely to treat many diseases in Burkina Faso, although no scientific data has been reported about its mechanism of action. In the present study the effects of its leaf extracts were investigated on calcium signalling in rat cultured skeletal muscle cells. The results show that the different extracts (crude decoction, aqueous, ethanolic and chloroformic extracts) have significant antagonistic effect on caffeine-induced calcium release from sarcoplasmic reticulum. Crude decoction is the most active followed by ethanolic, aqueous and chloroformic extracts in dose-dependent manner and can partly justify the use of the plant in traditional medicine.

Animals↗
PubMed2001

Cationic channels in normal and dystrophic human myotubes.

Human skeletal muscle cells obtained from normal and Duchenne muscular dystrophy patients were cocultured with explants of rat dorsal root ganglions. Single-channel recordings were performed with the cell-attached configuration of the patch-clamp technique and negative pressure was applied via the patch-pipette in order to mechanically stimulate the membrane patch. Inward elementary current activity was recorded under control or negative pressure conditions. Its occurrence and mean open probability were higher in Duchenne muscular dystrophy. Amplitude histograms reveal that these channels have a small unitary conductance of around 10 pS in 110 mM Ca2+ and could be inhibited in a dose-dependent manner by gadolinium. Results show that the membrane stress favoured calcium permeation through these channels. Taken together these data provide arguments for the involvement of such channels in calcium overload previously observed in cocultured dystrophic human (Duchenne muscular dystrophy) muscle cells.

Animals↗
PubMed2001

A case-control study of nonsyndromic oral clefts in Maryland.

PURPOSE: Isolated, nonsyndromic oral clefts cases (n = 171) and unaffected controls (n = 182) were used to identify both genetic and environmental risk factors. METHODS: Infants born in Maryland between 1992 to 1998 with an isolated, nonsyndromic oral cleft [cleft lip (CL), cleft lip and palate (CLP), or cleft palate (CP)] were recruited and exposure plus family history data were collected. Controls were unaffected infants. DNA was collected from all cases and their parents, plus controls. RESULTS: No statistically significant association was found between any of the following: maternal smoking, vitamin use, urinary tract infection, or recreational drug use in either univariate analysis or after adjusting for maternal age and education. More control mothers reported alcohol use during the critical time period of pregnancy (one month before conception through the first trimester) as compared to case mothers. There was a 10-fold increase in risk to siblings of cases as compared to siblings of controls. Markers at four candidate genes were examined: transforming growth factor alpha (TGF alpha), transforming growth factor beta 3 (TGF beta 3), MSX1, and BCL3. Only MSX1 showed significant differences in allele frequencies between CP cases and controls. MSX1 also showed significant evidence of linkage disequilibrium with a susceptibility gene controlling risk for CP. CONCLUSION: Most environmental risk factors examined here gave little evidence of association with risk to isolated, nonsyndromic oral clefts, although any alcohol consumption seemed protective. MSX1 showed evidence of linkage disequilibrium in both case-control and case-parent trio analysis.

Case-Control Studies↗
PubMed2001

Calcium homeostasis and cell death in Sol8 dystrophin-deficient cell line in culture.

Abnormalities of calcium homeostasis are involved in the process of cell injuries such as Duchenne muscular dystrophy characterized by the absence of the protein dystrophin. But how the absence of dystrophin leads to cytosolic calcium overload is as yet poorly understood. This question has been addressed with skeletal muscle cells from human DMD muscles or mdx mice. Although easier to obtain than human muscles, mdx muscle cells have provided controversial data concerning the resting intracellular calcium level ([Ca2+](i)). This work describes the culture of Sol8 cell line that expresses neither dystrophin nor adhalin, a dystrophin-associated protein. The [Ca2+](i)and intracellular calcium transients induced by different stimuli (acetylcholine, caffeine and high potassium) are normal during the first days of culture. At later stages, calcium homeostasis exhibits drastic alterations with a breaking down of the calcium responses and a large [Ca2+](i)elevation. Concomitantly, Sol8 cells exhibit morphological signs of cell death like cytoplasmic shrinkage and incorporation of propidium iodide. Cell death could be significantly reduced by blocking the activity of calpains, a type of calcium-regulated proteases. These results suggest that Sol8 cell line provides an alternative model of dystrophin-deficient skeletal muscle cells for which a clear disturbance of the calcium homeostasis is observed in culture in association with calpain-dependent cell death. It is shown that transfection with a plasmid cDNA permits the forced expression of dystrophin in Sol8 myotubes as well as a correct sorting of the protein. This approach could be used to explore possible interactions between dystrophin deficiency, calcium homeostasis alteration, and dystrophic cell death.

Acetylcholine↗
PubMed2001

A single center experience with the freestyle bioprosthesis: midterm results at the Québec Heart Institute.

Stentless bioprostheses show excellent early hemodynamic performance. However, longevity still remains unknown. This study reports midterm follow-up in 419 patients in which a Freestyle bioprosthesis (Medtronic Heart Valves, Minneapolis, MN) was inserted between January 1993 and January 2000 at the Quebec Heart Institute (Ste-Foy, Québec, Canada). Mean age at implantation was 68.0 +/- 8.2 years. Implantation was subcoronary in 81.9% of the patients, as a root replacement in 16.5%, and as a root inclusion in 1.7%. Mortality at 30 days was 6.2% for the whole cohort (2.8% for isolated subcoronary aortic valve replacement). Female gender, root implantation, valve sizes 19 to 21 mm, previous surgery, a history of stroke and diabetes were identified as predictors of 30-day mortality. Actuarial freedom from all death causes was 81.5% at 7 years; freedom from valve-related deaths 97.0%, and freedom from cardiac deaths 92.7%. Freedom from thromboembolic events was 86.1% at 7 years (55.1% of events were < 30 days). Freedom from endocarditis and hemorrhagic complications were respectively 98.5% and 95.6% at 7 years. Six patients required reoperations for valve explantation: 2 for endocarditis, 2 for structural dysfunction, and 2 for nonstructural dysfunction. Incidence of moderate or severe valve insufficiency at annual echocardiographic follow-up was: discharge: 0.6%; year 1: 0.7%; year 2: 1.3%; year 3: 3.3%; year 4: 3.7%; year 5: 2.6%; year 6: 0%. At 6 years after implantation, mean transvalvular gradient and effective valve orifice area were comparable to the year 1 values. This single center experience with the Medtronic Freestyle prosthesis shows preserved hemodynamic performance and low valve-related complications at midterm.

Actuarial Analysis↗
PubMed2000

Expression of the sodium/calcium exchanger in mammalian skeletal muscle cells in primary culture.

Previous investigations have demonstrated molecular and functional expression, at early phases of development of skeletal muscle cells in primary culture, of cardiac isoforms of proteins involved in calcium transport and regulation, like the L-type calcium channel. Here the expression of the cardiac isoform of the Na(+)/Ca(2+) exchanger (NCX1) was studied in skeletal muscle cells developing in vitro, by using biochemical, immunological, and electrophysiological techniques. Northern and Western blot experiments revealed the presence of this cardiac exchanger and its increasing expression during the early phases of development. Confocal imaging of myotubes showed an NCX1 distribution that was predominantly sarcolemmal. The whole-cell patch-clamp technique allowed us to record ionic currents, the direction and the amplitude of which depended on extracellular sodium and calcium concentrations. The developmental changes of this functional expression could be correlated with the molecular NCX1 expression changes. Taken together these data demonstrate the presence of the NCX1 isoform of the Na(+)/Ca(2+) exchanger during in vitro myogenesis and reinforce the theory that significant levels of cardiac-type proteins are transiently expressed during the early phases of the skeletal muscle cell development.

Animals↗
PubMed2000

Infantile refsum disease in four Amish sibs.

Infantile Refsum disease (IRD) appears with varying degrees of impaired vision, hearing loss, developmental delays, and neuromotor deficiencies. We report on four Amish sibs with IRD from a consanguineous marriage; biochemical testing supported the diagnosis of IRD. Of particular interest in this sibship are characteristic poorly formed yellow-orange teeth in at least three of the four affected sibs and behavior problems in the affected females.

Adolescent↗
PubMed2000

Primitive neuroectodermal tumor of the diaphragm: a case report.

We present a case of primitive neuroectodermal tumor (PNET) arising from the diaphragm in a neonate. PNETs are rare malignant tumors that belong to the group of small, round, blue-cell neoplasms of childhood. To the best of our knowledge, a PNET originating from the diaphragm has not been previously reported.

Age Factors↗
PubMed2000

A deprivation index for health and welfare planning in Quebec.

Given that one of the goals of public health policy in Quebec and Canada is to reduce social inequalities in health and welfare, it is surprising, to say the least, that most information systems in this field make no mention of people's socio-economic characteristics. The present article proposes an index to reflect the material and social dimensions of deprivation as this concept has been developed by Peter Townsend and other authors. The article describes the method used to create the index, which uses census data and tools developed by Statistics Canada to match postal codes with enumeration areas. Examples are provided of the use of the index in information systems covering three aspects of health and welfare in Quebec: deaths, hospitalizations and births. The value of the information provided by this index in planning health and social services is demonstrated.

Adult↗