Search PubMed⌕ Search

Biomedical subjects

B Picard

Publications and source records attributed to B Picard.

At least 37 records · Page 2Linked to original sources
PubMed2000

Effects of muscle type, castration, age, and compensatory growth rate on androgen receptor mRNA expression in bovine skeletal muscle.

The effect of testosterone on sexual dimorphism is evident by differential growth of forelimb and neck muscles in bulls and steers. Divergent hormone sensitivites may account for the differential growth rates of individual muscles. Therefore, the objective of this study was to compare androgen receptor (AR) expression in three different muscles of bulls and steers at various ages and growth rates. Thirty Montbéliard bulls and 30 steers were assigned to four slaughter age groups. Four or five animals of each sex were slaughtered at 4 and 8 mo of age. Animals in the remaining two slaughter groups (12 and 16 mo) were divided into groups of either restricted (R) or ad libitum (AL) access to feed. Five animals of each sex and diet were slaughtered at the end of the restricted intake period at 12 mo of age. To simulate compensatory growth, the remaining animals (R and AL) were allowed ad libitum access to feed until slaughter at 16 mo of age. Total RNA was extracted from samples of semitendinosus (ST), triceps brachii (TB), and splenius (SP) muscles. Androgen receptor mRNA was quantified in 200-ng total RNA preparations using an internally standardized reverse transcription (RT) PCR assay. Data were analyzed using 18S ribosomal RNA concentrations as a covariable. Steers had higher AR mRNA levels per RNA unit than bulls (P < .01). Androgen receptor mRNA levels differed between muscles (P < .05), with lowest expression in the SP. The pattern of AR expression differed (P < .05) for each muscle with increasing age. Between 4 and 12 mo of age, AR mRNA levels increased (P < .05) in SP but remained unchanged in the ST and TB. Feeding regimen had no effect on muscle AR expression, but steers exhibiting compensatory growth had higher AR mRNA levels than AL steers (P < .01) or bulls (P < .01). Our results show that AR expression is muscle-specific and may be modulated by circulating testicular hormones. These data suggest that the regulation of AR expression may be linked to allometric muscle growth patterns in cattle and compensatory gain in steers.

Aging↗
PubMed2000

[Molecular epidemiology of large bacterial endemics in Sub-Saharan Africa].

Over the past decades, the differentiation of bacterial strains for epidemiological purposes had been based on conventional phenotypic characters. More recently, methods studying the directly coded molecules or semantides (nucleic acids or proteins) have allowed, concomitantly with the technical progresses of electrophoresis, the description of stable, discriminant, reproducible markers, which were applicable to large series of isolates. Initially applied to study nosocomial infections in industrialised countries, these methods appear to be particularly suitable for an approach of the epidemiology of endemic bacterial infections in sub-Saharan Africa. The fact that these tools remain costly and technically complicated explains that most of these studies are conducted in the laboratories of industrialized countries. This research reveals the epidemiological complexity of most of these infections. Thus, the epidemiology of trachoma was studied by the analysis of polymorphism of the major outer membrane protein gene of Chlamydia trachomatis in a village of Gambia. A PCR based technique was used to determine the frequency of infection in symptomatic and clinically negative subjects and to specify the prevalence of the genotypes. The epidemiology of plague was studied by the restriction fragment length polymorphism (RFLP) analysis of the ribosomal RNA genes (ribotyping). Distinct ribotypes differentiated the strains of the first two pandemics from the third one. The strains of African origin were particularly heterogeneous, especially in Kenya. This diversity may be explained by the fact that the plague focus is extremely ancient in Central Africa. Bacterial agents of meningitis were also studied. The electrophoretic polymorphism of outer membrane proteins of Haemophilus influenzae of b type was used to specify the epidemiology of meningitis in Gambia. The invasive strains exhibited distinct profiles from non-invasive strains. Different types were evidenced in the west, east and central parts of the country. The antigenic polymorphism of outer membrane proteins of Neisseria meningitidis allowed the differentiation of the strains isolated in Mali according to the period of isolation. Thus, the endemic strains of A serotype were distinguished from those belonging to the same serotype, which were responsible for the 1994 epidemic. Several molecular methods were applied to the typing of Vibrio cholerae strains, particularly those of the seventh pandemic. The enzyme electrophoretic polymorphism (MLEE), a technique based on RFLP analysis of toxin genes, the arbitrarily primed PCR (AP-PCR) and mainly the ribotyping were applied. This last method revealed that in Africa several clones of V. Cholerae El Tor were responsible for the seventh pandemic. Moreover the technique has evidenced the intercontinental spread of a clone of V. Cholerae isolated in 1993 in Calcutta and identified a year later in Guinea-Bissau. Tuberculosis is at present the first opportunistic infection linked to HIV infection in sub-Saharan Africa. Tuberculosis incidence is particularly high and is expected to increase. Several molecular methods, including IS 6110 RFLP analysis, AP-PCR and spoligotyping were used to study the epidemiology of tuberculosis in various countries: South Africa, Tanzania, Zimbabwe, Kenya and Malawi. The aims of this research varied: prevalence of reactivation and of recently acquired infections, routes of contamination, degree of genetic diversity of the organisms isolated in a given geographic area, urban and rural origins of the infections, comparison of isolates from HIV seropositive and HIV seronegative patients. Identical profiles in the strains isolated from several patients could correspond to clusters of infections. However, the identification of epidemiological links in most clusters is hard to obtain. (ABSTRACT TRUNCATED)

Africa South of the Sahara↗
PubMed1999

Water resistance of resin-bonded joints with time related to alloy surface treatment.

OBJECTIVES: This paper attempts to study the resistance of resin-bonded metallic joints to damage in water with time. METHODS: Unlike the shear or tensile test, a cleavage test (Double Cantilever Beam test) allows us to follow the crack propagation in water, according to the fracture mechanics concept. Moreover, it is possible to follow the kinetic degradation of the metal/resin interface because this test is not totally destructive to the assembly. We have worked on 18 batches according to the nature of the alloys (Pd, Pd-Ag, Au, Co-Cr and Ni-Cr) and the surface treatment (sandblasting, Silicoater MD, Rocatec, V-Primer). The crack length was measured over a period of 20 days. The results are expressed in terms of adherence energy. RESULTS: The adherence energy dramatically decreased with time in water. The slope of the regression straight line appears to be a good criterion for evaluating the durability of the alloy/adhesive interface. We have demonstrated the importance of silica coating and, especially, the effectiveness of the Rocatec system upon the degree of hydrolytic degradation, and have shown how the development of cracks depends upon surface treatment.

Coated Materials, Biocompatible↗
PubMed1999

Regulation of bovine satellite cell proliferation and differentiation by insulin and triiodothyronine.

Satellite cells activity contributes to postnatal muscle growth. Herein, we have studied the respective influence of insulin and triiodothyronine (T3) on the proliferation and differentiation of primary bovine satellite cells isolated from Semitendinosus muscle of Montbéliard steers. Under basal conditions, satellite cells proliferated until the fifth day of culture, began to fuse into myotubes and expressed differentiation markers such as connectin, myogenin, and myosin heavy chain (MHC) isoforms. Insulin behaved as an effective mitogen. Moreover, it promoted extensive myotube formation and enhanced differentiation as shown by an increase in the accumulation of differentiation markers. Maximal differentiation occurred with insulin physiological range concentrations. A delay in the stimulation of differentiation was registered with a high dose that promoted maximal proliferation. Conversely, T3 decreased cell proliferation in a dose-dependent manner. In addition, fusion and biochemical differentiation (accumulation of connectin, MyoD1, myogenin, and myosin heavy chain isoforms) were also enhanced. Bovine satellite cells seemed to respond differentially to insulin and T3 for proliferation. Interestingly, both hormones displayed a myogenic influence. Our observations suggest that both hormones could influence bovine satellite cells in vivo and contribute to the regulation of postnatal muscle growth.

Animals↗
PubMed1999

Changes in the metabolic and contractile characteristics of muscle in male cattle between 10 and 16 months of age.

Samples of semitendinosus muscle from 28 male cattle (18 Salers and 10 Limousins) were taken at 10 months (biopsy) and at 16 months of age (at slaughter). The animals had received the same diet and were slaughtered after the same duration of fattening. The activities of isocitrate dehydrogenase and lactate dehydrogenase were measured in the muscle samples. The five lactate dehydrogenase isoenzymes were separated by electrophoresis under non-denaturing conditions and assayed by densitometry. Fibres were identified by histochemistry by myofibrillar ATPase and succinate dehydrogenase activities as SO (slow oxidative), FOG (fast oxidative glycolytic) or FG (fast glycolytic), and by immunohistochemistry by their reaction to monoclonal antibodies specific to slow and fast myosin heavy chain reactions in I, IIC, IIA, IIAB and IIB type fibres. The isocitrate dehydrogenase activity was not modified between 10 and 16 months of age; the lactate dehydrogenase activity decreased and was correlated with an increase in the proportion of the H isozyme to the detriment of the proportion of the M form. This period was characterized by an increase in fibre size, increased expression of MHC IIa, resulting in more IIA fibres, less IIB fibres, and an increase in the percentage of type IIAB fibres, however the proportions of SO, FOG and FG, when analysed statistically, were not modified between 10 and 16 months of age.

Adenosine Triphosphatases↗
PubMed1999

Genetic variability of foetal bovine myoblasts in primary culture.

Selected strains of adult bovines and those which either have high muscle growth capacity or are double-muscled present particular characteristics of muscle fibres and collagen at slaughter that favour meat tenderness. For double-muscled bovines, it has been shown that these characteristics originated during foetal life. However, no studies have been done to determine the origin of muscle growth superiority in bovine with high muscle growth capacity compared to those with a low muscle growth capacity. Therefore, the objective of this study was to examine the proliferation and differentiation phases of myoblasts in primary culture taken from high and low muscle growth capacity foetuses at 110 days post-conception. These cultures were analysed on 1, 2, 3, 4, 6, 8, 10 days of culture. The proliferation phase was monitored by appropriate marker antibodies. The differentiation was studied by immunocytochemistry with specific antibodies for foetal, I, II (IIa and IIb), I and IIb, I and IIa myosin heavy chains (MHCs) and connectin respectively, and by immunoblotting with desmin antibody. A higher proliferation, a lower fusion and a delayed differentiation of the 'late markers' namely MHCs fast (IIa and IIb) and connectin were shown in high muscle growth capacity foetuses compared to low capacity ones. The results indicate that the muscle growth superiority of high muscle growth capacity bovines seems, therefore, to have a similar foetal origin to that of double-muscled ones.

Animals↗
PubMed1999

Influence of surface treatment on adherence energy of alloys used in bonded prosthetics.

Usually, shear or tensile tests are used to assess bond strengths between resin and metal. In this study, a cleavage test, the Double Cantilever Beam test, was performed to measure the adherence energy in air and in water between a 4-META resin, and five alloys (palladium, palladium-silver, gold, cobalt-chromium and nickel-chromium alloys) whose surfaces have been treated by sandblasting only or by two methods of silica coating (Silicoater MD, Rocatec) or by painting with a primer (V-Primer). Results showed that, after storage in water, it is difficult to divide the studied alloys into a dental base alloys group and a noble alloys group. Therefore, the silica coating has significantly limited the propagation of fissures in water. Higher values of adherence energy were recorded with the Rocatec system except with the palladium alloy which must be treated with the Silicoater MD system. The treatment with V-Primer was sensitive to hydrolytic attack.

Acrylic Resins↗
PubMed1999

Age-related changes and location of type I, III, IV, V and VI collagens during development of four foetal skeletal muscles of double-muscled and normal bovine animals.

The aim of this work was to study the variability in the quantities of hydroxyproline, of type I and III collagens and in the location of types, I, III, IV, V, VI in four muscles of normal and double-muscled (DM) cattle. Samples were collected from foetuses at different ages post-conception. Both in the two genetic types and in muscles, from 110 days, types I, III, V, VI were located in perymisium and types I, IV, V, VI in endomysium. The amounts of hydroxyproline and of type I collagen increased from 150 to 180 or 230 days then decreased up to 260 days, with a trend to lower quantities in muscles of DM animals. Depending on the muscle and of the genetic type, amounts of type III, or changed as those of type I, or remained stable. Whatever the genetic type, at the end of gestation, proportions of type I and III in the total collagen are not identical in the four muscles, differences between muscles being particularly marked for type III, CT and MA muscles being the richer in this type. In addition, these two muscles contained less type III in DM animals than in normal ones.

Aging↗
PubMed1999

The link between phylogeny and virulence in Escherichia coli extraintestinal infection.

Previous studies suggesting a link between Escherichia coli phylogenetic groups and extraintestinal virulence have been hampered by the difficulty in establishing the intrinsic virulence of a bacterial strain. Indeed, unidentified virulence factors do exist, and the susceptibility of the host to infection is highly variable. To overcome these difficulties, we have developed a mouse model of extraintestinal virulence to test the virulence of the strains under normalized conditions. We then assessed the phylogenetic relationships compared to the E. coli reference (ECOR) collection, the presence of several known virulence determinants, and the lethality to mice of 82 human adult E. coli strains isolated from normal feces and during the course of extraintestinal infections. Commensal strains belong mainly to phylogenetic groups A and B1, are devoid of virulence determinants, and do not kill the mice. Strains exhibiting the same characteristics as the commensal strains can be isolated under pathogenic conditions, thus indicating the role of host-dependent factors, such as susceptibility linked to underlying disease, in the development of infection. Some strains of phylogenetic groups A, B1, and D are able to kill the mice, their virulence being most often correlated with the presence of virulence determinants. Lastly, strains of the B2 phylogenetic group represent a divergent lineage of highly virulent strains which kill the mice at high frequency and possess the highest level of virulence determinants. The observed link between virulence and phylogeny could correspond to the necessity of virulence determinants in a genetic background that is adequate for the emergence of a virulent clone, an expression of the interdependency of pathogenicity and metabolic activities in pathogenic bacteria.

Adult↗
PubMed1999

In vitro study of the retention and mechanical fatigue behavior of four implant overdenture stud-type attachments.

This study sought to determine the influence of mechanical fatigue on four varieties of implant overdenture studtype attachments (Supra-Snap, O'Ring, TSIB, ZAAG). Measurements of the initial vertical retentive force and the weight of the implant abutment were recorded. The same procedure was performed after the equivalent of 2 months, 6 months, and 12 months of clinical wear. For the four attachments, weight variation of the abutment between 0 and 1,080 cycles demonstrated no significant difference. Results indicated the TSIB to be significantly most retentive; next most retentive was the O'Ring, followed respectively by Supra-Snap and ZAAG.

Dental Prosthesis Design↗
PubMed1998

Comparison of five typing methods for the epidemiological study of Listeria monocytogenes.

Five typing methods were compared in a study designed to adapt a strategy for epidemiologically typing large numbers of Listeria monocytogenes strains. The methods studied were serotyping, electrophoretic typing of esterases (zymotyping), restriction fragment length polymorphism of ribosomal DNA (ribotyping), random amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE). Data were analysed by computer-assisted statistical analysis. Included in the analysis were 35 strains of L. monocytogenes, including 14 epidemic strains isolated during outbreaks in France in 1992 and 1993, and 21 strains isolated from food and the environment. Five serotypes, eight zymotypes, ten ribotypes, 13 RAPD patterns and 12 PFGE patterns were identified among the 35 strains. The most discriminating combination of typing methods was ribotyping and PFGE typing [27 types, discriminatory index (D.I.) = 0.978]. A factorial analysis of correspondence for each method differentiated the epidemic strains from the environmental strains. This study shows that computer-assisted statistical treatment of the data, combined with the use of discriminating typing methods, is a powerful tool for the epidemiological analysis of Listeria monocytogenes.

Animals↗
PubMed1998

Panmictic structure of Helicobacter pylori demonstrated by the comparative study of six genetic markers.

We compared the classifications of strains obtained by analysis of several genetic markers to demonstrate the panmictic structure of Helicobacter pylori, previously suggested by the study of multilocus enzyme electrophoresis. A series of 39 strains, including 37 clinical isolates from patients with gastritis or ulcers from two regions of France, reference strain CIP 101260 and the Sydney strain (strain SSI), were used. They were studied by restriction fragment length polymorphism analysis of ribosomal DNA (ribotyping) using HindIII and HaeIII, by polymorphism analysis of the ureA-ureB and flaA genes by PCR-RFLP using HaeIII and MboI, by vacA genotyping and by the presence or absence of the cagA gene and of the insertion sequence IS605 detected by PCR. There was a high level of genetic polymorphism over the studied strains, with 38 ribotypes, 38 restriction profiles for the ureA-ureB gene, 19 restriction profiles for the flaA gene and five combinations of the signal and mid-region sequences of the vacA gene. Factorial analysis of correspondence and hierarchical clustering performed using each marker revealed that the different classifications of the strains were not correlated. This suggests there is much genetic recombination between strains and supports the hypothesis of a panmictic structure for the H. pylori species.

Bacterial Proteins↗
PubMed1998

A study of relationships among F17 a producing enterotoxigenic and non-enterotoxigenic Escherichia coli strains isolated from diarrheic calves.

We investigated the clonal relationships among 41 enterotoxigenic (ETEC) or non-enterotoxigenic (NETEC) Escherichia coli strains producing the F17 a fimbriae isolated from diarrheic calves in France or Belgium in the early 1980s. Twenty-three of the 26 ETEC strains were highly clonally related, most of them with a O101:K32:H9-serotype. The NETEC strains were also divided in clonal subgroups, most of them with O101:H-serotype. The F17 a positive ETEC strains are no longer isolated from diarrheic calves in these countries. It is postulated that the use of a vaccine including O101, K32 and H9 antigens in addition to K99 (F5) explains the strongly reduced isolation of the O101:K32:H9, K99 (F5) E. coli clone.

Animals↗
PubMed1998

Classification of bovine muscle fibres by different histochemical techniques.

The classification of bovine muscle fibres is of particular interest for the food industry because meat tenderness depends in part on the proportion of the different types of fibres. It is, therefore, important to define reliable methods for classifying fibre types. There are several classification systems. One is based on contractile type alone, as revealed by myofibrillar ATPase activity or with antibodies against myosin heavy chain. Others take both contractile and metabolic types into account. In this study, the classifications of fibres obtained by these three systems were compared on the semitendinosus and longissimus thoracis muscles of 35 Charolais bulls. Only the use of antibodies allowed the identification of a proportion of hybrid fibres containing two isoforms of fast myosin heavy chain (2a and 2b). In addition, the combination of metabolic types showed that the metabolism of these hybrid fibres differed according to the muscle.

Animals↗
PubMed1998

Age-related changes and location of type I, III and IV collagens during skeletal muscle development of double-muscled and normal bovine foetuses.

The aim of this study was to investigate age-related changes in collagen content in muscles of normal and double-muscled (DM) bovine foetuses. Psoas major (PM) and triceps brachii (TB) muscles were collected from foetuses at 110 to 260 days post-conception (p.c.), frozen and powdered. Cyanogen bromide (CNBr) digestion and hydroxyproline measurements were carried out on the powder. CNBr peptides underwent SDS-polyacrylamide gel electrophoresis, and type I and III collagen relative variations were measured by densitometric analysis. Type I and III procollagen mRNA were located by in situ hybridization and types I, III and IV collagen located by indirect immunofluorescence. Although there was no significant difference between normal and DM animals in the amounts of collagen (except in PM muscle at 180 and 230 days p.c.), there was nevertheless a tendency to lower collagen content in muscles of DM animals. Amounts of hydroxyproline in PM and TB muscles from 110 to 230 days p.c. increased two- and threefold to 8.5 micrograms per mg of dry matter (d.m.) and 12 micrograms per mg d.m., respectively, and then decreased up to 260 days p.c., when they were twice as high in TB muscle (9.1 micrograms per mg d.m.) as in PM (4.5 micrograms per mg d.m.). The same difference in hydroxyproline levels was observed between normal adult PM and TB muscles. These variations were explained, mainly, by those of type I. In foetal muscle, in both genotypes and as in adult muscle, perimysium was types I and III, and endomysium type I, III and IV. Procollagen type I and III mRNA were located in perimysium. In conclusion, this study emphasizes that at the end of foetal life, collagen content is representative of what it will be in adult in muscle of both normal and DM animals.

Aging↗
PubMed1998

Phylogenetic analysis of Escherichia coli strains causing neonatal meningitis suggests horizontal gene transfer from a predominant pool of highly virulent B2 group strains.

Phylogenetic relationships of 69 neonatal meningitis Escherichia coli strains isolated worldwide were studied. Restriction fragment length polymorphism of rrn operons (rrn RFLP) in these isolates was compared with that of the 72 strains of the ECOR reference collection. Distributions of K1 antigen, of polymerase chain reaction-detected ibe10 gene, pap, afa, sfa/foc, hly, and aer operons, and of a 14.9-kb rrn-containing HindIII fragment previously associated with neonatal meningitis were compared. Oligoclonality was observed for the meningitis strains. Factorial analysis of correspondence on the rrn RFLP data showed a frequency gradient of meningitis strains from the phylogenetic B2 group (68%) to the A group (6%), via the D and B1 groups (26%). The distribution of the virulence determinants argues for their horizontal transfer during the evolution of E. coli. Analysis of the status of some neonates further suggests that neonatal meningitis results from a balance between bacterial genes of virulence and host factors.

Bacterial Typing Techniques↗
PubMed1997

Epidemiologically related and unrelated strains of Pseudomonas aeruginosa serotype O12 cannot be distinguished by phenotypic and genotypic typing.

A clonal origin for European isolates of antibiotic multi-resistant Pseudomonas aeruginosa serotype O12 has been suggested. This study was designed to assess the value and limitations of several typing methods for the investigation of outbreaks due to this serotype. In Hôpital de Rodez, France, this organism is endemic, and a prospective clinical epidemiological study was undertaken over a 15 month period, encompassing all patients at the hospital from whom P. aeruginosa O12 was isolated. All isolates were examined by auxanogram, antibiogram, phage-typing, electrophoresis of esterases and pulsed-field gel electrophoresis of DNA. The results suggest that (1) the methods used did not clearly differentiate between clinically-related and epidemiologically-unrelated European isolates, (2) in Hôpital de Rodez, while some isolates were likely to have been transmitted from patient-to-patient, most infections or colonizations with this organism were sporadic and their origin is unknown. The limits of typing methods for the investigation of outbreaks of nosocomial infection with multi-resistant P. aeruginosa O12 are emphasized.

Aged↗