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C Girard

Publications and source records attributed to C Girard.

At least 55 records · Page 3Linked to original sources
PubMed2000

N-glycosylation and residue 96 are involved in the functional properties of UDP-glucuronosyltransferase enzymes.

The recent cloning of several human and monkey UDP-glucuronosyltransferase (UGT) 2B proteins has allowed the characterization of these steroid metabolic enzymes. However, relatively little is known about the structure-function relationship, and the potential post-translational modifications of these proteins. The mammalian UGT2B proteins contain at least one consensus asparagine-linked glycosylation site NX(S/T). Endoglycosidase H digestion of the human and monkey UGT2B proteins demonstrates that only UGT2B7, UGT2B15, UGT2B17, and UGT2B20 are glycosylated. Although UGT2B15 and UGT2B20 contain three and four potential glycosylation sites, respectively, site-directed mutagenesis revealed that both proteins are glycosylated at the same first site. In both proteins, abolishing glycosylation decreased glucuronidation activity; however, the K(m) values and the substrate specificities were not affected. Despite the similarities between UGT2B15 and UGT2B20, UGT2B20 is largely more labile than UGT2B15. Treating HK293 cells stably expressing UGT2B20 with cycloheximide for 2 h decreased the enzyme activity by more than 50%, whereas the activity of UGT2B15 remained unchanged after 24 h. The UGT2B20 protein is unique in having an isoleucine at position 96 instead of an arginine as found in all the other UGT2B enzymes. Changing the isoleucine in UGT2B20 to an arginine stabilized enzyme activity, while the reciprocal mutation in UGT2B15 R96I produced a more labile enzyme. Secondary structure predictions of UGT2B proteins revealed a putative alpha-helix in this region in all the human and monkey proteins. This alpha-helix is shortest in UGT2B20; however, the helix is lengthened in UGT2B20 I96R. Thus, it is apparent that the length of the putative alpha-helix between residues 84 and 100 is a determining factor in the stability of UGT2B enzyme activity. This study reveals the extent and importance of protein glycosylation on UGT2B enzyme activity and that the effect of residue 96 on UGT2B enzyme stability is correlated to the length of a putative alpha-helix.

Amino Acid Sequence↗
PubMed2000

Optical addressing at the subwavelength scale

The Green dyadic formalism is applied to the study of the optical properties of dielectric subwavelength structures integrated in coplanar geometry. We first consider homogeneous wires with high refractive index featuring subwavelength cross sections. We show that such wires may have guiding properties and that they may be coupled with a local illumination produced by a focused Gaussian beam totally reflected at the substrate interface. When excited by the focused beam, these subwavelength optical waveguides (SOW's) provide a confined source of light that could be used to excite a single nanoscopic object. Well designed heteregeneous wires resulting from the alignment of dielectric particles separated from each other by a subwavelength distance are also found to propagate a Gaussian beam excitation over several micrometers. This propagation occurs with reasonable damping for incident beams in the visible frequency range. The computed transmission spectra of these heterowires may exhibit narrow gaps. Finally, we discuss the relation between the optical properties of the SOW and the calculated electromagnetic local density of states.

Journal Article↗
PubMed2000

Synovial sarcoma in an Ayrshire heifer.

An 8-month-old Ayrshire heifer had a rapidly growing mass in the axillary region of the left thoracic limb. The mass surrounded the distal humerus and entrapped nerves of the brachial plexus, causing an abnormal gait. Histologically, the mass was composed of clusters and cords of round to polygonal cells with scattered, spindle-shaped cells. The neoplastic cells stained positively for vimentin and cytokeratin. No staining was found with S-100 protein, kappa and lambda light chains, or T-cell markers by immunohistochemistry. On electron microscopic evaluation, the cytoplasm of the neoplastic cells contained few organelles, principally rough and smooth endoplasmic reticulum and mitochondria. This synovial sarcoma has histologic and ultrastructural features characteristic of the poorly differentiated subtype of synovial sarcoma in the human classification system.

Animals↗
PubMed2000

3'-azido-3'-deoxythimidine (AZT) is glucuronidated by human UDP-glucuronosyltransferase 2B7 (UGT2B7).

3'-Azido-3'-deoxythymidine (AZT) is frequently prescribed to patients infected with the human immunodeficiency virus. After absorption, AZT is rapidly metabolized into 3'-azido-3'-deoxy-5'-glucuronylthymidine by UDP-glucuronosyltransferase (UGT) enzymes. Using labeled [(14)C]UDP-glucuronic acid and microsomal preparations from human kidney 293 cells stably expressing the different human UGT2B isoenzymes, it was demonstrated that AZT glucuronidation is catalyzed specifically by human UGT2B7. The identity of the metabolite formed was confirmed as AZT-G by liquid chromatography coupled with mass spectrometry. UGT2B7 is encoded by a polymorphic gene and kinetic analysis of AZT glucuronidation by the two allelic variants UGT2B7(H(268)) and UGT2B7(Y(268)), yielded apparent K(m) values of 91.0 and 80.1 microM, respectively. Normalization to protein levels yielded glucuronidation efficiency ratios (V(max)/K(m)) of 21.3 and 11.0 microl. min(-1). mg protein(-1) for UGT2B7(H(268)) and UGT2B7(Y(268)), respectively. It remains possible that other UGT enzymes are also involved in AZT conjugation; however, the glucuronidation of AZT by UGT2B7, which is a UGT2B protein expressed in the liver, is consistent with previous findings and supports the physiological relevance of this enzyme in AZT conjugation.

Alleles↗
PubMed2000

[Inhaled nitric oxide: therapeutic applications in cardiac surgery].

The occurrence of right ventricular failure secondary to pulmonary arterial hypertension is a major postoperative complication of cardiac surgery in children and adults. The selective pulmonary vasodilation produced by inhaled nitric oxide (NO) constitutes a fundamental therapeutic advance in the management of this pathology. NO binds immediately with haemoglobin, resulting in its immediate inactivation. This results in perfect maintenance of systemic and coronary blood pressures. A first study performed in 1989 after mitral valve replacement for mitral stenosis with pulmonary hypertension and clinical trials after surgical correction for congenital heart disease and heart transplantation with pulmonary hypertension suggested the efficacy and safety of 20 to 40 ppm NO concentrations in these indications. Potential toxicity of NO (NO2 production by oxidation, methaemoglobin formation) leads to caution with its use. Monitoring of NO concentration and methaemoglobin production is recommended, especially in new-borns.

Administration, Inhalation↗
PubMed1999

[Ten-year experience with heart transplantation (1987-1997)].

OBJECTIVES: Analyze ten years experience with heart transplantation at the Dijon University Hospital and determine which parameters control mid and long term outcome. PATIENTS AND METHODS: One hundred thirty six heart transplantations were performed over a 10 year period (1987-1997) in 118 men and 18 women aged 51-87 years. Heart transplantation was indicated on the basis of the following criteria: ejection fraction *20%, pulmonary arteriole resistance < 6 Wood units, peak oxygen uptake < 14 l/kg/min. The Shumway or anatomic technique was used. The triple immunosuppressive protocol combined corticosteroids, azathioprine and cyclosporin. The same team conducted the post-transplantation follow-up with regular programmed consultations in addition to those requested by the general practitioner, the cardiologist or the patient. Follow-up was oriented according to the clinical situation (blood chemistry, cell counts, cyclosporinemia, search for infection, echocardiography, endomyocardial biopsy, coronarography). RESULTS: Five patients (3.6%) died when still on the waiting list. Absolute emergency transplantation was performed for patients (28.1%) including 8 (5.9%) after circulatory assist. Hospital mortality was 11.7% and late mortality was 16.1%. Actuarial survival was 78% at 1 year, 71% at 5 years and 69% at 10 years. Among the survivors, 94% were taking two, three or even four drugs for hypertension. Cyclosporin levels decreased and creatinine levels increased. Episodes of rejection were minimal: 86.57% of the biopsies were * grade 1 and 4.45% * grade 2. Cytomegalovirus infection was documented and treated in 7.55% of the cases. Incidence of graft coronary artery disease was 3.4% at 1 year, 6.5% at 2 years and 7.9% at 3 years. CONCLUSION: Our follow-up structure where the same small team conducts regular examinations together with our approach to heart transplantation appears to be the main factor leading to the quality results obtained in this series.

Aged↗
PubMed1999

Molecular cloning of a gut-specific chitinase cDNA from the beetle Phaedon cochleariae.

A cDNA encoding a chitinase of Pheadon cochleariae was isolated from a larval gut library. The cDNA encodes a preenzyme with a putative 20 amino-acid signal peptide and a 385 amino-acid mature enzyme of calculated mass of 42.7 kDa. Amino-acid alignment shows 24-33% identity to other insect and crustacea chitinases. The sequence lacks C-terminus domains but active site residues are conserved. Northern analysis localizes the mRNA to guts of feeding larvae. Southern blot analysis, with a complete cDNA probe, suggests that the P. cochleariae genome may contain several chitinase genes. Activity gels show that two groups of chitinases are expressed in the insect. One group comprises chitinases of 30-40 kDa that are active at pH 5.0 and detected in guts of feeding larvae and adults, as well as in pre-pupae and pupae. The other group comprises chitinases of 40-70 kDa that are more active at pH 7.0 and are mainly expressed in pre-pupae and pupae. The biological significance of both groups of chitinases is discussed.

Amino Acid Sequence↗
PubMed1999

Molecular cloning of cDNAs encoding a range of digestive enzymes from a phytophagous beetle, Phaedon cochleariae.

To gain better knowledge of the variety of digestive enzymes in phytophagous coleopteran pests, a sequencing screen of 76 random cDNAs from a gut library from Phaedon cochleariae larvae was performed. The screen yielded 21 cDNAs encoding amino-acid sequences homologous to known digestive enzymes, most of them were cell wall-hydrolysing enzymes. The deduced protein sequences of 7 cDNAs encoding putative alpha-amylase, cysteine proteinase, trypsin, chymotrypsin, cellulase, pectinase and xylanase display all the structural features that characterize these enzymes in other eukaryotic organisms. Except the alpha-amylase and chymotrypsin cDNAs, the other cDNAs probably derive from multigene families. The distribution of the corresponding enzymatic activities at various developmental stages of P. cochleariae was examined. alpha-amylase activity is present in guts of larvae and adults, proteinases are abundant in guts of larvae and adults, but scarce in eggs and larval carcasses, xylanases are present in the guts of larvae and adults, as well as in carcasses of larvae, whereas cellulase and pectinase activities are distributed in larval and adult guts, larval carcasses, and eggs. Only a minor fraction of the cellulases is secreted by microorganisms, suggesting that P. cochleariae synthesizes most of its own cell-wall hydrolysing enzymes. The physiological role of the enzymes is discussed, as well as the significance of these results for pest management strategies involving transgenic plants expressing enzyme inhibitors.

Amino Acid Sequence↗
PubMed1999

Polyoxygenated flavones from the leaves of comptonella microcarpa

The leaves of Comptonella microcarpa have yielded one alkaloid, dictamnine, and four known polyoxygenated flavonoids, meliternatin, 3,5,8-trimethoxy-6,7-3',4'-dimethylenedioxyflavone, 7-(3-methylbut-2-enyloxy)-3,5,8-trimethoxy-3', 4'-methylenedioxyflavone (3), 7-hydroxy-3,5,8-trimethoxy-3', 4'methylenedioxyflavone. In addition, two new flavonoids were found whose structures were established on the basis of their spectral data as 7-hydroxy-3,5,6,8-tetramethoxy-3',4'-methylenedioxyflavone (1) and 7-(3-methylbut-2-enyloxy)-3,5,6,8-tetramethoxy-3', 4'-methylenedioxyflavone (2).

Journal Article↗
PubMed1999

Resonant optical tunnel effect through dielectric structures of subwavelength cross sections.

We show that optical tunnel effects through elongated structures of subwavelength cross sections can be enhanced by the appropriate structuration of the local dielectric function. Even under total internal reflection, transfer channels can be excited to perform spatially confined photonic transfer between transparent media linked by such subwavelength structures. The optical properties of such systems are analyzed using field susceptibilities, also known as electromagnetic Green's dyadics, which determine both the local density of photon states and the optical transmittance of the system. Green's dyadics obtained by solving numerically a set of dyadic Dyson equations are applied to study the optical properties of subwavelength structures connecting two semi-infinite materials.

Journal Article↗
PubMed1999

Intrapericardial neoplasia in dogs.

A retrospective study was conducted from 1,919 necropsies of dogs, and 52 cases were selected on the basis of primary or metastatic neoplasia in the pericardium, the heart base, or the myocardium. Primary intrapericardial neoplasms were more frequent than intrapericardial metastases. Hemangiosarcomas were the most frequent primary neoplasms, followed by chemodectomas. Lymphomas were the most frequent metastatic neoplasms, followed by fibrosarcomas and rhabdomyosarcomas. Other neoplasms, either primary or metastatic, occurred rarely.

Animals↗
PubMed1998

Description of 14 cases of bovine hypokalaemia syndrome.

The records of 14 cases of bovine hypokalaemia observed between 1983 and 1996 were reviewed. The most common history included a protracted, often infectious, disease. All age groups were represented. Although previously reported as a risk factor, isoflupredone acetate had not been administered to five of the cases. The following clinical signs were recorded in 10 cases: abnormal position of the head and neck, severe weakness, rumen hypomotility or atony, abnormal faeces, anorexia and tachycardia. Cardiac dysrhythmia was observed in six cases. Acid-base imbalance (alkalosis in 10 cases), hyperglycaemia and increased activities of aspartate aminotransferase and creatine kinase were associated with hypokalaemia ranging from 1.35 to 2.49 mmol/litre. Treatments included symptomatic treatment, supportive care and potassium chloride given intravenously and orally at an average total daily dose of 42 g/100 kg bodyweight (26 g by mouth and 16 g intravenously) for an average of five days. Eleven cases recovered after an average of three days.

Animals↗
PubMed1998

Growth stimulation of beetle larvae reared on a transgenic oilseed rape expressing a cysteine proteinase inhibitor.

The resistance of a transgenic line of oilseed rape expressing constitutively the cysteine proteinase inhibitor oryzacystatin I (OCI) was assessed against Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae). The levels of OCI expression in the transformed line averaged 0.2% and 0.05% of total soluble protein in leaves and petioles respectively. In vitro analyses showed that P. chrysocephala larvae use both cysteine and serine proteinases for protein digestion, and that all the cysteine proteolytic activity is OCI-sensitive. However, bioassays showed that adults fed identically on leaf discs from control or transformed plants. When larvae were reared on transgenic plants expressing OCI, they showed an increase in weight gain compared to those reared on control plants. Furthermore, those larvae from transgenic plants exhibited a 2-fold increase in both cysteine and serine proteolytic activity as a reponse to the presence of OCI. The plasticity of insect digestive physiology and feeding behaviour are discussed, as well as the relevance of engineering a genotype expressing both types of proteinase inhibitors.

Journal Article↗
PubMed1998

Two strains of cabbage seed weevil (Coleoptera: Curculionidae) exhibit differential susceptibility to a transgenic oilseed rape expressing oryzacystatin I.

The aim of this study was to assess the potential effect of a transgenic line of oilseed rape expressing oryzacystatin I (OCI) on two strains of cabbage seed weevil. The level of OCI expression in seeds was approximately 0.05% of total soluble proteins. The insects were field-collected in two different locations, and their progeny was analyzed after a 3 week-development in pods. Both strains showed a similar pattern of proteolytic activity, and similar levels of OCI-sensitive proteinase activity in vitro. However, the larvae showed differential susceptibility to the transgenic plants. Despite inhibition of digestive proteinases in vitro by OCI in both strains, one strain showed an increased growth rate when fed the transgenic seeds, while the other strain remained unaffected. While suggesting the importance of studying individuals from different populations when assessing the effect of proteinase inhibitor-expressing plants on insect growth, our results also point out the necessity of studying the biochemical interactions taking place in vivo between the recombinant inhibitors and their target proteinases.

Journal Article↗
PubMed1998

High level of resistance to proteinase inhibitors may be conferred by proteolytic cleavage in beetle larvae.

Incorporation of genes encoding proteinase inhibitors into oilseed rape genome could confer resistance to Coleoptera, which are the major pests on rape in Europe. A detailed study of the digestive proteinase of a model cruciferous-feeding Coleoptera, Phaedon cochleariae, showed that this insect relies on a complex proteolytic system including serine, cysteine, aspartyl proteinases, and leucine aminopeptidases. The inhibition of general and specific activities by a range of proteinase inhibitors in vitro suggested that oryzacystatin I (OCI) and Bowman-Birk inhibitor (BBI) would have adverse effects when ingested by the larvae. However, the growth and the feeding of larvae reared on oilseed rape leaf discs treated with a high dose of OCI and/or BBI were not affected. Moreover, the levels and patterns of proteolytic activities were not modified in these larvae. The study of the interactions between P. cochleariae larval proteinases and OCI and BBI revealed that both inhibitors were rapidly cleaved by serine proteinases in association with leucine aminopeptidases, and consequently lost their inhibitory capacity. This mechanism of resistance is very efficient, and may be widespread among Coleoptera. The major implications for insect control using proteinase inhibitor-based strategies are discussed.

Animals↗
PubMed1998

Use of polymerase chain reaction and immunohistochemistry for detection of canine adenovirus type 1 in formalin-fixed, paraffin-embedded liver of dogs with chronic hepatitis or cirrhosis.

To assess the possible involvement of canine adenovirus type 1 (CAV-1) in naturally occurring cases of canine chronic liver disease, a polymerase chain reaction (PCR)-based assay was developed to detect a conserved region of the major core protein gene (pVII) of CAV-1 in formalin-fixed, paraffin-embedded liver sections. Results were compared with a standard avidin-biotin immunoperoxidase complex technique that detected CAV-1 antigens using a commercial monoclonal anti-adenovirus antibody. Seventeen cases of cirrhosis and 28 cases of chronic hepatitis with piecemeal necrosis and progressive fibrosis were selected for the study. Formalin-fixed, paraffin-embedded liver sections of 2 cases of infectious canine hepatitis (ICH) and crude DNA extract from CAV-1 (ATCC VR 293 Utrecht strain) served as positive controls. A 411-base-pair viral region was amplified and sequenced as CAV-1 pVII in both cases of infectious canine hepatitis and in the CAV-1 crude DNA extract. The 2 ICH cases were positive for CAV-1 antigens by the immunoperoxidase method. CAV-1 DNA or antigens were not detected by either technique in any of the 45 cases of chronic liver disease selected for the study. These results indicate that both PCR and immunohistochemistry are reliable and rapid techniques for detecting CAV-1 in formalin-fixed, paraffin-embedded liver sections of dogs with ICH. Several possibilities may explain the negative results obtained with both techniques in this study, including the noninvolvement of CAV-1 in canine chronic hepatitis and cirrhosis and the possibility that the virus causes initial damage, provokes a self-perpetuating chronic liver disease, and disappears.

Adenoviridae Infections↗