Biomedical subjects

C Leroux

Publications and source records attributed to C Leroux.

At least 19 recordsLinked to original sources

PubMed2006

Telomerase activation in a model of lung adenocarcinoma.

Ovine pulmonary adenocarcinoma (OPA) is a lung cancer strikingly similar to the pneumonic-type mixed invasive adenocarcinoma with a predominant bronchioloalveolar component in humans. Telomerase activity in OPA and the potential involvement of the kinase Akt in telomerase activation and regulation of cell proliferation were investigated. Lung tissues were collected from sheep with a histopathological diagnosis of OPA or controls. Epithelial cell cultures were derived in vitro from lung tissues. Telomerase activity was evaluated using the telomeric repeat amplification protocol method. Phosphorylation of Akt was detected by Western blotting. Telomerase activity was significantly higher in OPA lung tissues compared to control lung tissues. A high telomerase activity was detected in eight out of 12 (67%) primary cell cultures derived from tumours. A high level of expression of phosphorylated Akt was found in 10 out of 27 (37%) tumours, with abolition of Akt activation in response to epidermal growth factor stimulation demonstrated in primary cell cultures derived from tumours. Telomerase activation takes place in ovine pulmonary adenocarcinoma tumour cells and may be partly attributable to Akt activation. Telomerase may inhibit cellular senescence and contribute to the accumulation of tumour cells in mixed adenocarcinoma with a bronchioloalveolar component. Further work is necessary to identify alternative signalling pathways of telomerase activation in tumours.

Adenocarcinoma↗

PubMed2005

Mammary lipid metabolism and milk fatty acid secretion in alpine goats fed vegetable lipids.

Fourteen Alpine goats at midlactation were fed a diet of hay and concentrate (55:45), without (control) or with formaldehyde-treated linseed (FLS) or oleic sunflower oil (OSO) at 11.2 or 3.5% of dry matter intake, respectively, in a 3 x 3 Latin Square design with three 3-wk periods. Milk yield was lower in goats fed FLS than control or OSO (2.13 vs. 2.32 kg/d). Milk fat content was higher with FLS or OSO than control (40.8 vs. 33.8 g/kg). Formaldehyde-treated linseed and OSO caused a significant decrease (23 and 18%, respectively) of C10 to C17 fatty acids secretion compared with control. The secretion of cis-9 C18:1 and cis-9, trans-11 C18:2 were increased 1.44- and 1.54-fold for FLS and 1.78- and 1.36-fold for OSO, compared with control. The C18:3 (n-3) secretion was increased 2.61-fold with FLS compared with control. Milk cis-9 C14:1/C14:0, cis-9 C16:1/C16:0, and cis-9 C18:1/C18:0 ratios decreased with the supplemented diets compared with control. Mammary stearoyl-CoA desaturase mRNA and activity were decreased by the lipid supplements, whereas no significant change was observed for acetyl-CoA carboxylase and fatty acid synthase. The activities of glucose-6-phosphate dehydrogenase, malic enzyme, and glycerol-3-phosphate dehydrogenase were not affected by the lipid supplements. Mammary lipoprotein lipase mRNA increased with OSO, whereas lipoprotein lipase activity tended to decrease with FLS compared with control. Milk lipoprotein lipase activity sharply decreased with lipid supplement (by 59 and 71%, for FLS and OSO, respectively). The changes in milk fatty acid profile due to FLS and OSO supplements were partly related to changes in the levels of mammary enzyme activities or mRNA.

Animal Feed↗

PubMed2005

A cDNA macroarray resource for gene expression profiling in ruminant tissues involved in reproduction and production (milk and beef) traits.

cDNA arrays have proven to be useful tools to screen gene expression in many animal species including livestock species. A collaborative program was launched to construct a ruminant cDNA collection, representative of three tissues: Muscle, Embryo and Mammary gland, named MEM. This collection gathers clones mainly arising from 3 non-normalised cDNA libraries: a directed bovine muscle library, a 14-day-old bovine embryo library and a goat lactating mammary library. It is made up of 1896 clones (637 muscle, 882 embryo and 377 mammary cDNAs), selected after sequencing and bioinformatic analyses. Amplification products yielded from these clones as well as controls were printed onto Nylon membranes to generate macroarrays. Hybridisation with relevant cDNA targets allowed checking the location of about 50 cDNAs and the specificity of each sub-set of the repertoire. Macroarrays were hybridised with radiolabelled cDNA complex targets from five different tissues (muscle, embryo, mammary gland, adipose tissue and oocyte). Both somatic and germinal complex targets gave valid hybridisation signals with 45 to 80% of the printed probes. This specific cDNA collection now provides a powerful tool for transcriptomic studies with the ultimate objective to better understand physiological and metabolic functions in ruminants. It will be subsequently included into a forthcoming larger collection.

Animals↗

PubMed2004

A collection of bovine cDNA probes for gene expression profiling in muscle.

Array technology has been increasingly used to monitor global gene expression patterns in various tissues and cell types. However, applications to muscle development and pathology as well as meat production in livestock species have been hampered by the lack of appropriate cDNA collections. To overcome this problem, a directed cDNA library was constructed starting from 23 muscles of meat-producing bovines to derive a collection of 3573 clones. A preliminary sequence characterization of this collection indicated that the most abundant transcripts correspond to genes encoding proteins involved in energy metabolism (COX and NADH dehydrogenase subunits) and belonging to the contractile apparatus (myosin chains and troponin isoforms). From this cDNA library, we selected a set of 435 clones representing 340 unique genes, of which 24 were novel. This collection was subsequently completed with 75 specific cDNA probes for genes of interest already studied in our laboratory. The bovine 'muscle' cDNA repertoire thus designed was spotted onto a nylon membrane (macroarray) in order to test its utility to further investigate the transcriptome of bovine muscles in relation to meat quality traits. It is also anticipated that this type of collection might be useful for the study of chronic myologic diseases in other mammalian species, including humans.

Animals↗

PubMed2004

Apoptosis in right-ventricle biopsy is not predictive of graft survival.

Myocardial dysfunction is common in grafted hearts from brain-dead donors, but the mechanisms involved remain unclear, although apoptosis has been suggested to play an important role. In this study, we investigated the presence of apoptotic myocardial cells in donor hearts as compared to control hearts to determine whether pre-existing apoptosis can predict donor heart dysfunction. Apoptosis was studied by in situ DNA fragmentation assay and by Western Blotting for caspase-3, the pivotal executive caspase of the apoptotic pathway. We show that brain-death induced myocardial apoptosis was not predictive of myocardial dysfunction in transplanted hearts.

Adult↗

PubMed2003

Endogenous retroviruses related to jaagsiekte sheep retrovirus.

Ovine betaretroviruses consist of exogenous viruses [jaagsiekte sheep retrovirus (JSRV) and enzootic nasal tumor virus, (ENTV)] associated with neoplastic diseases of the respiratory tract and 15-20 endogenous viruses (enJSRV) stably integrated in the ovine and caprine genome. Phylogenetic analysis of this group of retroviruses suggests that the enJSRV can be considered as 'modern' endogenous retroviruses with active, exogenous counterparts. Sequence analysis of JSRV, ENTV and enJSRV suggests that enJSRV do not directly contribute to the pathogenesis of ovine pulmonary adenocarcinoma (OPA) or enzootic nasal tumor through large-scale recombination events, but small-scale recombination or complementation of gene function cannot be excluded; experiments involving enJSRV-free sheep, which have not been found, would be needed to investigate this possibility. Evidence of expression of enJSRV structural proteins in tissues of the reproductive tract and lung implies that they do not have a primary role in disease. However, experimental exploitation of exogenous/endogenous retrovirus sequence differences by producing chimeras has been useful in establishing the determinants of JSRV Env-induced transformation. Even if enJSRV do not have a direct role in OPA, their expression during ontogeny or in neonatal life may impact the likelihood of exogenous JSRV infection and disease outcome via the induction of immunological tolerance. Aside from any role in disease, enJSRV loci may serve as useful genetic markers in the sheep and their frequent expression in the reproductive tract of the ewe may portend an important physiologic role in sheep.

Age Factors↗

PubMed2003

Pathology of human bronchioloalveolar carcinoma and its relationship to the ovine disease.

Lung cancer is a leading cause of cancer with a poor prognosis. Bronchioloalveolar carcinoma (BAC) is a rare tumor that has always intrigued physicians. Since the last World Health Organization classification the pathology has been clarified; BAC per se is an adenocarcinoma with a pure bronchioloalveolar growth pattern and appears as an in situ alveolar adenocarcinoma. More usually BAC is a clinically recognizable entity presenting as multi-focal nodules evolving towards pneumonia associated with pulmonary shunting. Pathology is that of a multifocal mixed adenocarcinoma: bronchioloalveolar and papillar. Whatever the stage, survival is better than in other forms of non-small cell lung cancer (NSCLC). The true frequency of BAC is unknown, although it is a rare form of lung cancer; smoking cannot be excluded as a risk factor. It appears that p53 and ras genes are less often mutated than in other lung adenocarcinomas, suggesting that the cellular mechanisms involved are different. Ovine pulmonary adenocarcinoma (OPA) presents with the same symptoms as BAC in humans and is caused by a betaretrovirus Jaagsiekte sheep retrovirus. Very early on, clinical and histological similarities with human BAC were stressed. A recent series of OPA described, according to the third edition of the WHO classification for human lung cancer, mixed adenocarcinoma, BAC and papillary and/or acinar carcinoma. An immunohistochemical study suggested that some human pulmonary tumors (including BAC) may be associated with a Jaagsiekte sheep retrovirus-related retrovirus,but so far no molecular study has confirmed this observation. Thus, OPA is an exquisite model of carcinogenesis for human lung adenocarcinomas.

Adenocarcinoma, Bronchiolo-Alveolar↗

PubMed2002

Intrascrotal hernia of the ureter and fatty hernia.

Intrascrotal hernia of the ureter is a rare event. We describe here one such case. There are two anatomic types of such ureteral hernias. The paraperitoneal type has a peritoneal indirect sac, which pulls the ureter with it. The extraperitoneal ureteral hernia is without a peritoneal sac. In such cases, which are almost always indirect hernias, there is usually a large amount of fat. It is, in fact, retroperitoneal fat, which slides, and pulls the ureter with it by gravity. Such a case is a genuine prolapse of the retroperitoneal structures. This anomaly, which has been rarely studied, is worth knowing about, because the ureter may be damaged during hernia dissection. The surgeon should be cautious when discovering huge fatty hernias, and should avoid the excision of fat and simply return the fatty mass to its normal place after its separation from the cord.

Adipose Tissue↗

PubMed2002

[Intrascrotal herniation of the ureter].

We describe one case of intra-scrotal hernia of the right ureter. The anomaly was recognized on a pre-operatory urogram. It was an extra-peritoneal ureteral hernia. There are two types of ureteral hernia: the para-peritoneal hernia with a peritoneal sac; the extra-peritoneal type with only a fatty hernia. The mecanism of the latter illustrated by our case is a prolapse of the retro-peritoneal fat. It is not possible to practice an urogram before the cure of every inguinal hernia, so the prevention in this rare situation of the damage of ureter is to be cautious in the resection of huge lipomas and sliding fat when operating on inguinal hernias.

Aged↗

PubMed2002

[Recklinghausen's disease and gastrointestinal stromal tumors].

Gastro-intestinal stromal tumors associated with Recklinghausen's disease should be considered in the current concept of the stromal tumors with reference to recent advances in immuno-chemistry. In this setting, there is an high potential of maluignancy. For the treatment of these lesions, surgery is the main tool. Frequency of malignant digestive diseases associated with Recklinghausen disease should be kept in mind.

Duodenal Neoplasms↗

PubMed2002

Leptin expression in the ovine mammary gland: putative sequential involvement of adipose, epithelial, and myoepithelial cells during pregnancy and lactation.

We examined the ability of the ovine mammary gland to synthesize leptin throughout pregnancy and lactation. Leptin gene expression was assayed by real-time reverse transcription and polymerase chain reaction in mammary gland from ewes at 15, 80, 106, 112, or 141 d of pregnancy and at 0 (30 min after parturition), 3, 48, or 70 d of lactation. Leptin mRNA level was high at the beginning (the first 80 d) and at the end of pregnancy and was lower at mid-pregnancy and throughout lactation. Furthermore, during these periods of mammary leptin expression, the location of leptin protein, as determined by immunohistochemical analysis, changed within mammary tissue. It was located in adipose cells during early stages of pregnancy, in epithelial cells after full cell differentiation just before parturition, and in myoepithelial cells after parturition. These data, compared with published data on leptin receptor gene expression, provide evidence that leptin could be produced by different cell types of the mammary gland and could act as a paracrine factor on mammary cell growth and differentiation via adipose-epithelial cells and myoepithelial-epithelial cell interactions.

Adipocytes↗

PubMed2001

Characterization of the caprine stearoyl-CoA desaturase gene and its mRNA showing an unusually long 3'-UTR sequence arising from a single exon.

A 5-kb long transcript encoding the stearoyl-CoA desaturase (SCD) was identified by Northern-blot analysis of poly(A)+ mRNA from caprine lactating mammary gland. Complete sequencing of the SCD cDNA (5123 bp) revealed that the coding region (1080 nt) is followed by an unusually long (3.8 kb) 3'-UTR sequence, deriving from a single exon, in which a polymorphism, due to the deletion of a nucleotide triplet, was detected. The complete structural organization of the relevant gene has been determined. The transcription unit was shown to span a 15-kb region and to consist in six exons varying in size from 131 (3rd exon) to 4047 bp (6th exon), and five introns varying in size from 600 to 3700 bp. Using the fluorescence in situ hybridization technique, the SCD gene was localized to bovine and caprine chromosomes 26q21, and ovine chromosome 22q21.

3' Untranslated Regions↗

PubMed2001

Aortic aneurysm: construction of a life-size model by rapid prototyping.

Development of new endovascular techniques for repair of abdominal aortic aneurysm (AAA) requires the use of experimental models. Stereolithography is a rapid prototyping technique used in industry to prototype parts during the design phase. A stereolithography apparatus (STL) employs laser technology to build a digital model layer by layer with photopolymer resin. The purpose of this study was to use this technology to produce a life-size AAA model. Data were acquired by CT scan and stored in DICOM 3 format. Specifically designed software was used for 3-D imaging and conversion of data to a standard STL format. Two replicas were made: one to scale and the other 3 mm larger. The final model was made by pouring silicone rubber or polyurethane into the mold over the life-size model so as to obtain a sturdy, life-size, soft, transparent plastic casting. Arterial models made for living subjects with these rapid prototyping techniques can be used to simulate surgical procedures, calibrate imaging modalities, and design new stent grafts.

Aortic Aneurysm, Abdominal↗

PubMed2001

A fluorescent reverse transcription-polymerase chain reaction assay to quantify the lipoprotein lipase messenger RNA.

Relative quantitative reverse transcription-polymerase chain reaction (rqRT-PCR), which allows an accurate quantification of the amount of mRNA in samples potentially differing in the quality of their RNA preparation, was used to quantify lipoprotein lipase (LPL) mRNA in ovine adipose tissue. A comparative evaluation of four rqRT-PCR procedures was carried out. The amount of LPL mRNA was assayed relative to either that of gamma-actin (ACT) or cyclophilin (CYC) mRNA, used as endogenous standard. Independent (INACT and INCYC procedures) or simultaneous (COACT and COCYC procedures) amplifications have been compared. Fluorescently labelled primers yielded PCR products which were quantitatively analysed using an automated DNA sequencer. After optimizing the PCR cycle number and verifying that the amounts of ACT and CYC mRNA varied only weakly according to the nutritional conditions studied, we have tested the ability of the four procedures to quantify specific variations in LPL mRNA. The repeatability of each step and the overall assay reproducibility were also examined. The COACT and INCYC procedures were finally retained to accurately quantify LPL mRNA in AT from nine underfed or refed ewes, and gave highly correlated results (r=0.98, p<0.01). In addition, significant correlations (r=0.83, p<0.01 and r=0.92, p<0.01 for COACT and INCYC, respectively) were observed with the LPL activity in AT.

Actins↗

PubMed2001

Leptin in ruminants. Gene expression in adipose tissue and mammary gland, and regulation of plasma concentration.

This paper reviews data on leptin gene expression in adipose tissue (AT) and mammary gland of adult ruminants, as well as on plasma leptin variations, according to genetic, physiological, nutritional and environmental factors. AT leptin mRNA level was higher in sheep and goat subcutaneous than visceral tissues, and the opposite was observed in cattle; it was higher in fat than in lean selection line in sheep; it was decreased by undernutrition and increased by refeeding in cattle and sheep, and not changed by adding soybeans to the diet of lactating goats; it was increased by injection of NPY to sheep, and by GH treatment of growing sheep and cattle. Insulin and glucocorticoids in vitro increased AT leptin mRNA in cattle, and leptin production in sheep. Long daylength increased AT lipogenic activities and leptin mRNA, as well as plasma leptin in sheep. Mammary tissue leptin mRNA level was high during early pregnancy and was lower but still expressed during late pregnancy and lactation in sheep. Leptin was present in sheep mammary adipocytes, epithelial and myoepithelial cells during early pregnancy, late pregnancy and lactation, respectively. Plasma leptin in cattle and sheep was first studied thanks to a commercial "multi-species" kit. It was positively related to body fatness and energy balance or feeding level, and decreased by beta-agonist injection. The recent development of specific RIA for ruminant leptin enabled more quantitative study of changes in plasma leptin concentration, which were explained for 35--50% by body fatness and for 15--20% by feeding level. The response of plasma leptin to meal intake was related positively to glycemia, and negatively to plasma 3-hydroxybutyrate. The putative physiological roles of changes in leptin gene expression are discussed in relation with published data on leptin receptors in several body tissues, and on in vivo or in vitro effects of leptin treatment.

Adipose Tissue↗

PubMed2001

Effects of photoperiod and feeding level on adipose tissue and muscle lipoprotein lipase activity and mRNA level in dry non-pregnant sheep.

The aim of the present study was to investigate the effects of photoperiod and feeding level on lipid metabolism in ovine perirenal and subcutaneous adipose tissues (AT) and in skeletal and cardiac muscles. Twenty dry non-pregnant ovariectomised ewes were divided into two groups and subjected to either 8 h or 16 h light/d, and underfed at 22 % energy requirements for 7 d. Half of the ewes in each group were slaughtered and the remaining ewes were refed at 190 % energy requirements for 14 d, until slaughtering. Refeeding increased (2.6-4.3-fold) malic enzyme (ME), fatty acid synthase (FAS), glucose-6-phosphate dehydrogenase (G6PDH) and glycerol-3-phosphate dehydrogenase (G3PDH) activities in subcutaneous AT as well as lipoprotein lipase (LPL) activity in perirenal (3.5-fold) and subcutaneous (10-fold) AT and to a lesser extent (1.4-fold) in the skeletal longissimus thoracis and cardiac muscles. Moreover, variations of LPL mRNA level followed variations of LPL activity: refeeding increased perirenal AT- and cardiac muscle-mRNA levels (7.4- and 2-fold respectively). The main finding of this study is that, for a given level of food intake, long days (compared with short days) increased the LPL activity in the longissimus thoracis muscle and, in refed ewes, the activities of LPL and ME in subcutaneous AT. Furthermore, long days increased LPL mRNA level in cardiac muscle and perirenal AT. Thus, our results show that there are direct effects of photoperiod on sheep AT lipogenic potential, as well as on muscle LPL activity, which are not caused by changes in nutrient availability.

Adipose Tissue↗

PubMed2001

Equine infectious anemia virus genomic evolution in progressor and nonprogressor ponies.

A primary mechanism of lentivirus persistence is the ability of these viruses to evolve in response to biological and immunological selective pressures with a remarkable array of genetic and antigenic variations that constitute a perpetual natural experiment in genetic engineering. A widely accepted paradigm of lentivirus evolution is that the rate of genetic variation is correlated directly with the levels of virus replication: the greater the viral replication, the more opportunities that exist for genetic modifications and selection of viral variants. To test this hypothesis directly, we examined the patterns of equine infectious anemia virus (EIAV) envelope variation during a 2.5-year period in experimentally infected ponies that differed markedly in clinical progression and in steady-state levels of viral replication as indicated by plasma virus genomic RNA assays. The results of these comprehensive studies revealed for the first time similar extents of envelope gp90 variation in persistently infected ponies regardless of the number of disease cycles (one to six) and viremia during chronic disease. The extent of envelope variation was also independent of the apparent steady-state levels of virus replication during long-term asymptomatic infection, varying from undetectable to 10(5) genomic RNA copies per ml of plasma. In addition, the data confirmed the evolution of distinct virus populations (genomic quasispecies) associated with sequential febrile episodes during acute and chronic EIA and demonstrated for the first time ongoing envelope variation during long-term asymptomatic infections. Finally, comparison of the rates of evolution of the previously defined EIAV gp90 variable domains demonstrated distinct differences in the rates of nucleotide and amino acid sequence variation, presumably reflecting differences in the ability of different envelope domains to respond to immune or other biological selection pressures. Thus, these data suggest that EIAV variation can be associated predominantly with ongoing low levels of virus replication and selection in target tissues, even in the absence of substantial levels of plasma viremia, and that envelope variation continues during all stages of persistent infection as the virus successfully avoids clearance by host defense mechanisms.

Acute Disease↗

PubMed2000

Human immunodeficiency virus type 1 shedding pattern in semen correlates with the compartmentalization of viral Quasi species between blood and semen.

High levels of human immunodeficiency virus (HIV) type 1 have been detected in semen at all stages of disease. However, it is not clear whether HIV-1 is shed in semen continuously or intermittently. In a prospective longitudinal study, viral RNA was measured weekly for 10 weeks in semen and blood of HIV-seropositive subjects. Results showed three different patterns of HIV-1 shedding in semen: none (28%), continuous (28%), and intermittent (44%). In contrast, there was no change in blood plasma virus load during the study period. Phylogenetic analysis of the envelope sequences of HIV-1 RNA in semen and blood revealed distinct virus populations in semen and blood of intermittent shedders but similar virus populations in the semen and blood of continuous shedder. These results indicate for the first time that HIV-1 is shed primarily in an intermittent manner and that shedding patterns of HIV-1 in semen are related to compartmentalization of HIV-1 between semen and blood.

Cell Compartmentation↗