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Biomedical subjects

P Vigneron

Publications and source records attributed to P Vigneron.

At least 19 recordsLinked to original sources
PubMed2006

Interactions of B16F10 melanoma cells aggregated on a cellulose substrate.

There is evidence that the shape of cells and their contact with a matrix direct the growth and the differentiation of both normal and cancer cells. Cells in 3D culture resemble the in vivo situation more closely than do those in conventional 2D cultures. We have studied the interactions and functions of B16F10 mouse melanoma cells, which spread and grow well on tissue culture polystyrene (tPS), when they were made to aggregate on cellulose-coated Petri dishes (CEL). This aggregation of melanoma cells on CEL was Ca2+ dependent and mediated by N-cadherins. The levels of N-cadherin and beta-catenin transcripts in cells cultured on CEL and tPS were similar, but those on CEL contained less beta-catenin protein. Immunoprecipitation and immunostaining showed that both N-cadherins and beta-catenins were present at the membranes of cells on CEL. Cells proliferated significantly more slowly after 48 h on CEL and the cellulose coating caused most of them to arrest in G1. We also compared the melanin contents and tyrosinase activity of cells on CEL and controls grown on tPS. Melanogenesis was induced in cells aggregated on CEL. A cellulose substrate thus appears to be an outstanding tool for studying cell-cell interactions and cell functions in 3D cultures.

Animals↗
PubMed2003

Gene flow estimation with microsatellites in a Malagasy seed orchard of Eucalyptus grandis.

Eucalyptus grandis has a mixed-mating reproductive system. Malagasy Eucalyptus seed orchards were established 15 years ago with two aims both based on panmixia: open-pollinated seed production and genetic improvement. The panmixia hypothesis has never been confirmed in the seed orchard. From a seedling seed-orchard stand comprising 349 trees and using data obtained with six selected microsatellite markers, paternity analysis was performed for 724 offspring collected on 30 adult trees. Paternity assignment, based on exclusion procedures and likelihood-ratio method, was achieved with high accuracy; the exclusion probability value was 0.997. The outcrossing rate was very high (96.7%). More than 50% of potential male trees (199 out of 349) in the seed orchard contributed to pollination for 440 offspring of 30 progenies (8.6% of the basic population). The pollination rate from outside the seed orchard was high (39.2%), but might be due to the small size of this seed orchard. This study showed that "panmixia-like pollination" can be assumed.

Crosses, Genetic↗
PubMed2002

[Herpetic meningitis in the child].

UNLABELLED: In children, viral meningitis is usually caused by Enteroviruses. Herpes simplex viruses (HSV) are known to be a cause of meningo-encephalitis. HSV-2 has been reported to cause recurrent meningitis (Mollaret's meningitis) in adults. CASE REPORT: We report the case of a three-year-old girl with HSV-1 meningitis, whose evolution with treatment by aciclovir was good. CONCLUSION: HSV-1 has rarely been reported as a cause of isolated aseptic meningitis in children. Primary phase of herpes simplex virus infection is not usually associated with neurologic complications.

Acyclovir↗
PubMed1999

[Myocardiopathy and isolated glucocorticoid deficit with ACTH resistance: a fortuitous association?].

UNLABELLED: Hereditary syndrome of unresponsiveness to ACTH is a rare autosomal recessive disorder characterized by an isolated glucocorticoid deficiency which is exceptionally associated to regressive cardiomyopathy. CASE REPORT: A male newborn had iterative episodes of hypoglycemia since the first hours of life. Acute bronchiolitis at the age of 14 days was associated with transitory dilated cardiomyopathy. Hypoglycemia was due to glucocorticoid deficiency secondary to ACTH insensitivity. Molecular biology showed a composite heterozygotism for the ACTH receptor gene. CONCLUSION: Any congenital glucocorticoid deficiency should lead to search for cardiomyopathy.

Adrenal Insufficiency↗
PubMed1998

Expression of specific white adipose tissue genes in denervation-induced skeletal muscle fatty degeneration.

Denervation of skeletal muscle results in rapid atrophy with loss of contractile mass and/or progressive degeneration of muscle fibers which are replaced to a greater or lesser degree by connective and fatty tissues. In this study, we show that denervated rabbit muscles are transformed into a white adipose tissue, depending on their fiber types. This tissue does express LPL, G3PDH and particularly the ob gene, a white adipose tissue-specific marker, and does not express the brown adipose tissue molecular marker UCP1 mRNA.

Adipose Tissue↗
PubMed1998

Expression of lactate dehydrogenase, myosin heavy chain and myogenic regulatory factor genes in rabbit embryonic muscle cell cultures.

The expression of myogenic regulatory factors (MRFs), lactate dehydrogenase (LDH) and myosin heavy chains (MyHC), as markers of myogenesis, metabolism and contractility respectively, were investigated during differentiation of rabbit embryonic muscle cells in primary culture. Myf5, MyoD and myogenin mRNAs were abundantly expressed at day 1 of culture. The expression of Myf5 and MyoD mRNA transcripts decreased sharply as myoblasts fused and differentiated into myotubes, whilst myogenin mRNA was maintained throughout the duration of the culture. In contrast, MRF4 mRNA was weakly expressed on day 1 of culture, its expression increased slightly as myoblasts fused and reached a maximum level in 7-day-old cultures containing striated myofibres. The specific activity of LDH increased linearly during myoblast proliferation and fusion. In 7-day-old cultures, LDH-M mRNA (dominant in glycolytic muscles) and LDH-H mRNA (predominant in perinatal and oxidative muscles) represented 38% and 62% of total LDH mRNA respectively. At this stage, immunocytochemical staining with perinatal and adult-type MyHC antibodies showed that embryonic and perinatal MyHC isoforms were expressed in all myotubes, while few of them were stained by type I MyHC antibody. However, none of them expressed adult type II MyHC. The latter results were further supported by RT-PCR analysis of adult-type MyHC mRNA which showed that only the type I MyHC mRNA transcript was expressed. These data were in agreement with those reported in vivo on perinatal rabbit muscles. They differed from those obtained on cultured satellite cells isolated from adult rabbit fast-twitch or slow-twitch muscles which did not express embryonic MyHC, and instead expressed fast- or slow-type MyHC according to their muscle origin. Taken together, these results further suggest that myogenic mononucleated cells express different properties in vitro according to their developmental origin as well as properties related to those of the muscles from which they were isolated.

Animals↗
PubMed1998

Transformation of slow- or fast-twitch rabbit muscles after cross-reinnervation or low frequency stimulation does not alter the in vitro properties of their satellite cells.

We previously showed that satellite cells isolated from rabbit fast-twitch and slow-twitch muscles presented different behaviours in culture; cells from slow muscle differentiated more quickly and fused into more numerous myotubes than those from fast muscle. Moreover, only slow-muscle derived satellite cells expressed in vitro the slow type I myosin heavy chain isoform (MyHC). We wanted to investigate whether the properties of satellite cells originating from different muscles were under the influence of the adult fibre type on which they were located. For this purpose, we transformed the properties of the adult rabbit fast-twitch semimembranosus accessorius (SMa; approximately 100% type II fibres) and the slow-twitch semimembranosus proprius (SMp; 100% type I fibre) muscles by (1) cross-reinnervating the SMp with the main branch of the fast SMa nerve; or (2) electrical stimulation at 10 Hz of the SMa muscle. We studied their satellite cells in vitro. Five-month cross-reinnervation of the SMp induced a large shift of its MyHC type characteristics towards those of a fast muscle, and three-month electrical stimulation at low frequency transformed the fast-twitch SMa into a slow-twitch muscle, as shown by SDS-PAGE of MyHC. In spite of the transformation of their muscle characteristics, satellite cells in culture kept their original properties. Indeed, as shown by MyoD and myogenin gene expression as markers of fusion, satellite cells isolated from cross-reinnervated and from control SMp began to fuse by eight days of culture, and expressed MyoD and myogenin at that stage. Later they differentiated into numerous myotubes. Satellite cells isolated from electrically stimulated and control SMa presented a similar behaviour in culture: they did not express MyoD and myogenin at eight days, and fused by ten days into only a few myotubes. Moreover, MyHC gene expression showed that, in contrast with slow-muscle derived satellite cells, the type I MyHC gene was not expressed by satellite cells isolated from the stimulated SMa in spite of its homogeneous type I fibre composition. Taken together, these data support the idea that once constituted, muscle fibre types per se do not influence the properties of their associated satellite cells.

Animals↗
PubMed1996

Expression of myosin isoforms in denervated, cross-reinnervated, and electrically stimulated rabbit muscles.

The expression of myosin heavy (MyHC) and light (MyLC) chain isoforms was analyzed after denervation and cross-reinnervation by a fast nerve of the slow-twitch Semimembranosus proprius (SMp) muscle, and after denervation and electrical stimulation at low frequency of the fast-twitch Semimembranous accessorius (SMa) muscle of the rabbit. The control SMp (100% type I fibers) expressed 100% type I MyHC and 100% slow-type (1S', 1S and 2S) MyLC isoforms. Five month denervation did not alter significantly the MyHC expression of the muscle, but induced the expression of a new type 1 MyLC corresponding most probably to an embryonic MyLC. Five-month cross-reinnervation of the SMp by the fast SMa nerve induced a large change of its fiber type properties. As shown by immunocytochemistry, almost all fibers were stained by fast myosin antibody, but a high proportion of them co-expressed slow myosin. This result was in agreement with biochemical data showing that fast MyHC and MyLC isoforms became predominant. The control SMa (nearly 100% type II fibers) expressed almost 100% type II MyHC (70% type IIb and 22% IIx/d) and 100% fast-type (1F, 2F and 3F) MyLC isoforms. Five month denervation of the SMa induced a shift in its MyHC, with 98% type IIx/d and 2% type IIb isoforms, and no change in the proportions of its MyLC. Three month electrical stimulation at 10 Hz of the SMa transformed its fiber type composition. All fibers reacted with the slow myosin antibody and a minor proportion of them were stained by the fast myosin antibody. These observations were in agreement with the biochemical analysis showing a large predominance of the slow-type MyHC and MyLC isoforms. Taken together, these results obtained from rabbit muscles which are normally homogeneous in either fast-twitch or slow-twitch fiber types, further support the idea that the different myosin isoforms, particularly the MyHC, are differentially regulated by motor innervation. Type I MyHC is maintained in denervated SMp muscle, but is not expressed in denervated SMa. Type IIb isoform is the most sensitive to neural influence, as it disappears rapidly in denervated and electrically stimulated fast-twitch SMa muscle, and is barely expressed in cross-reinnervated slow-twitch SMp muscle. In contrast, type IIa and type IIx/d are less dependent upon motor innervation. In addition to the previous studies of d'Albis et al. analysis of these results leads us to conclude that, in the rabbit, sensitivity to motor innervation increases from the glycolytic to the oxydative types of fibers, in the order IIB > IIX/IID > IIA > I.

Animals↗
PubMed1991

Neural influence on the expression of acetylcholinesterase molecular forms in fast and slow rabbit skeletal muscles.

With the aim of investigating the roles of motor innervation and activity on muscle characteristics, we studied the molecular forms of acetylcholinesterase (AChE) in fast-twitch (semimembranosus accessorius; SMa) and slow-twitch (semimembranosus proprius; SMp) muscles of the rabbit. We have shown that SMa and SMp express different patterns and tissue distribution of AChE forms and that the effect of long denervation varies with age. Three principal findings concerning expression of AChE molecular forms emerge from these studies. (1) The activity of AChE and the pattern of its molecular forms are particularly altered in adult denervated SMa and SMp muscles. AChE activity increases by 10-fold in both muscles, but asymmetric forms disappear in SMa and increase by 20-fold in SMp muscles. A similar alteration of AChE is found after tenotomy of these muscles, showing that the effect of denervation may be partly due to suppression of muscle activity. (2) The different changes occurring in the composition of AChE molecular forms in adult denervated SMa and SMp muscles are consistent with fluorescent staining with anti-AChE monoclonal antibodies and with DBA or VVA lectins, which bind to AChE asymmetric, collagen-tailed forms. These lectins poorly stain denervated SMa muscle surfaces but intensely stain neuromuscular junctions and extrasynaptic areas in denervated SMp muscle. (3) In contrast with the adult, denervation of 1-day-old muscles does not markedly modify the total amount of AChE or the proportions of its molecular forms, despite dramatic effects on muscle structure. These results are supported by studies of labeling with fluorescent DBA: the lectin only slightly stains the muscle fiber surface of denervated 15-day-old SMp muscle. Taken together, these data show that denervated muscles escape physiological regulation, producing increased levels of AChE with highly variable cellular distribution and patterns of molecular forms, depending on the age of operation and on the type of muscle.

Acetylcholinesterase↗
PubMed1991

Effects of thyroid state alterations in ovo on the plasma levels of thyroid hormones and on the populations of fibers in the plantaris muscle of male and female chickens.

Propylthiouracil (PTU), thyroxine (T4) or thyreoliberin (TRH) were injected in ovo to modify the thyroid state of chicken embryos. Significant sexual differences were observed in the effects of these treatments on the plasma concentrations of thyroid hormones and on plantaris muscle characteristics (DNA, RNA, populations of muscle fibers) in 3- and 35-day old male and female chickens. The T4 plasma concentration is lower in control males; it is decreased in PTU treated females and in the T4 treated females at 35 days. The T3 plasma concentration is lowered at 3 days in all treated chickens and also at 35 days in the TRH treated animals. The slow (STnO) and the fast (FTOG) fibers of the plantaris are always more numerous in males. In controls, the number of FTOG fibers remains steady between 3 and 35 days; at the same time, the number of STnO fibers rises in males only. Both PTU and T4 treatments increase the number of the FTOG and the STnO fibers respectively before and after the 3rd day. TRH treatment increases the number of STnO fibers at 3 and 35 days in males, but reduces it at 3 days in females. Thus changes in the number of FTOG fibers can be induced during in ovo myogenesis, whereas the number of STnO fibers may increase after hatching.

Animals↗
PubMed1989

[Properties of skeletal muscle fibers. II. Hormonal influences].

The skeletal muscle contains fibers with various contractile and metabolic properties. These populations of muscle fibers differ in their sensitivity and their response to circulating hormones which also affect the muscular differentiation (multiplication and fusion of myoblasts into myotubes). This review deals with the regulations of energy metabolism and of protein synthesis in muscles by several hormones acting either directly, or in association with other hormones, or by induction of growth factors. In most cases, hormonal effects seem to depend on the type and level of activity of the constitutive muscle fibers. The muscle fiber types involved in the anabolic properties of estrogens have not yet been clearly described. In the case of growth hormone and insulin, the slow fiber type is mainly affected; their effects are partially mediated through an increased secretion of somatomedins (IGFs) or by interaction on IGF receptors. The other reported hormones or factors induce a shift toward a more potent fast contracting activity, ultimately increasing the percentage of fast glycolytic fibers. Androgens, catecholamines and beta-agonists are anabolic and produce an enlargement of these fibers, whereas thyroid hormones or glucocorticoids in excess increase their catabolism.

Animals↗
PubMed1988

Postnatal changes in insulin binding in slow and fast-twitch rabbit skeletal muscles.

Changes of insulin binding characteristics (number of receptors, Kd) were studied in the semimembranosus proprius (SMP) and psoas major (PM) muscle from birth to adult stage. The Kd was about 0.15 10(-9) M in both muscles and did not change with age. The numbers of receptors were similar in both muscles at birth and changed differently thereafter to reach 1.3 fmoles per mg of muscle in the PM and 5.6 in the SMP muscle.

Aging↗
PubMed1988

[Polymorphism of acetylcholinesterase and myosin during development of fast and slow muscles denervated in the newborn rabbit].

The rabbit Semimembranosus proprius (SMp) and Semimembranosus accessorius (SMa) muscles represent good models for studying the transformations of muscle properties during postnatal differentiation. In the adult, these muscles are homogeneous in slow twitch (SMp) and fast twitch (SMa) fibers, respectively. However, they are heterogeneous at birth and express their adult characteristics from two months onwards. During this period we studied the influence of motor innervation on the development of their properties, particularly at the level of acetylcholinesterase (AChE) molecular forms and myosin slow (LCs) and fast (LCf) light chains. The postnatal alteration of SMa and SMp muscles was characterized by the disappearance of the neonatal heterogeneity and the acquisition of the homogeneous fast or slow fiber type pattern. The fibers of these muscles denervated at birth were altered differently: dramatic atrophy of fast twitch fibers whatever the muscles studied, preservation of SMp slow twitch fiber characteristics and fatty degeneration of SMa. At birth, both muscles presented a similar pattern of myosin fast and slow LC. In control muscles, the alteration of fiber populations to homogeneous types led to the disappearance of supernumerary chains from 15 days onwards. In the slow muscle, neonatal denervation prevented LCf disappearance. In the fast muscle, denervation influenced essentially the installation of LCf which was delayed by 15 days. At birth, the polymorphism of AChE was similar in SMp and SMa muscles. One month after denervation, the specific activity of AChE was twice that of the control. Its polymorphism was not much disturbed, while in the adult denervation induced a large increase in AChE specific activity (x 10) and particularly a great alteration in its polymorphism according to the fast or slow muscle fiber types.

Acetylcholinesterase↗
PubMed1986

Ontogenesis of triiodothyronine nuclear receptors in three skeletal muscles in male and female chicks.

The ontogenesis of nuclear triiodothyronine receptors was determined in the pectoralis (alpha W fibers: fast contracting, glycolytic metabolism), adductor brevis (alpha R fibers: fast contracting, oxido-glycolytic metabolism) and adductor magnus (beta R fibers: slow contracting, oxidative metabolism), muscles of male and female chickens at 18 days in ovo and 0, 6, and 30 days ex ovo. In the fast muscles (adductor brevis and pectoralis major), the T3 receptor number decreases from the 18th day of incubation to hatching or the 6th day after hatching, respectively, and then increases. In the slow muscle (adductor magnus), the T3 receptor number increases from 18 days in ovo to hatching and then decreases. At 30 days after hatching, the number of T3 receptors was higher in the fast muscles than in the slow one. A comparison of the two fast muscles reveals that the number of T3 receptors was more elevated in the pectoralis (glycolytic) fibers than in the adductor brevis (oxido-glycolytic) fibers. An overall test of significance showed a higher number of T3 nuclear receptors in muscles from females than from males.

Animals↗