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C Charbonneau

Publications and source records attributed to C Charbonneau.

18 recordsLinked to original sources
PubMed2004

Functional dimorphism of two hAgRP promoter SNPs in linkage disequilibrium.

The agouti related protein (AgRP) exerts its anabolic effects on food intake by antagonising the alpha-melanocyte stimulating hormone (alpha-MSH) at its receptors, melanocortin receptors 3 and 4 (MC3R and MC4R). A single nucleotide polymorphism (SNP) in the promoter of the human AgRP (hAgRP), -38C>T, was associated with low body fatness. The -38T allele that was associated with low body fatness also resulted in lower promoter activity. Here we report a novel SNP, -3019G>A, again in the promoter of hAgRP, which is in complete linkage disequilibrium (LD) with the -38C>T SNP (linked alleles: -3019A/-38T and -3019G/-38C). Functional analyses in a human adrenal and two mouse hypothalamus cell lines showed that the -3019A allele had significantly higher promoter activity. Hence, the two linked alleles (-3019A and -38T) had opposite effects on promoter function and yet they were both associated with low body fatness. The region encompassing the -38C>T SNP had approximately 1000-fold higher activity than the region encompassing the -3019G>A SNP, potentially determining the net functional effect between these two SNPs.

Agouti-Related Protein↗
PubMed2003

Early dialysis in a neonate with intrauterine lisinopril exposure.

In general, angiotensin converting enzyme (ACE) inhibitors should be discontinued in pregnancy, as they can induce an ACE fetopathy. For the treatment of the latter, early peritoneal dialysis is recommended for in utero exposure to captopril and enalapril, although the outcome is poor. Early peritoneal dialysis has not previously been reported for lisinopril induced multiorgan failure. A case is reported in which treatment was given on postnatal day 3. The patient recovered from oligoanuria to almost normal renal function, and heart, brain, and musculoskeletal injury was reversible. This is despite relatively poor clearance of the drug through peritoneal dialysis. Analysis of the pharmacokinetic data suggests that haemodialysis or haemofiltration would be more efficacious for removal of the drug, and these treatments should be performed if available.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

The interactions of amphotericin B with various sterols in relation to its possible use in anticancer therapy.

Amphotericin B (AmB) is still the most common anti-fungal agent used to treat systemic fungal infections. It is known that this antibiotic acts by forming pores with the ergosterol contained in the membranes of fungi, but it also interacts with the cholesterol contained in the membranes of eukaryotic cells, hence its toxicity. AmB may also interact with the most common oxidation products of cholesterol found in vivo, together with interacting with biosynthetic precursors of cholesterol, namely, lanosterol and 7-dehydrocholesterol (7-DHC). The purpose of the present work was to study the interactions in solution between AmB and these various sterols, the techniques used being UV-Vis spectroscopy and differential scanning calorimetry. The results are globally interpreted in terms of the structural differences between the sterols. We show that AmB selectively interacts with 7-DHC which, according to a recent hypothesis proposed in the literature, has been identified in connexion with a therapeutic strategy against hepatocellular carcinomas. We find that the affinity of AmB towards 7-DHC is even greater than the affinity of the antibiotic towards ergosterol. We also find that AmB selectively interacts with the principal oxidation product of cholesterol, 7-ketocholesterol, a situation that has to be taken into account when AmB is administered.

Amphotericin B↗
PubMed2001

Central 5-hydroxytryptamine-2A receptor expression in transgenic mice bearing a glucocorticoid receptor antisense.

Transgenic mice bearing a transgene coding for a glucocorticoid receptor antisense mRNA that partially blocks glucocorticoid receptor expression were used to investigate the long-term effect of hypothalamic-pituitary-adrenal dysfunction on brain 5-hydroxytryptamine-2A (5-HT2A) receptor expression. The brain 5-HT2A receptor mRNA levels in transgenic mice were measured by in situ hybridization and compared to those in control mice. We also studied the effect of a 3-week treatment with fluoxetine on brain 5-HT2A receptor expression in the transgenic mice. No difference in 5-HT2A mRNA levels was observed between transgenic and control mice in cortical or striatal regions, and fluoxetine treatment was without effect. No difference in hypothalamic 5-HT2A mRNA levels was observed between transgenic and control mice, while fluoxetine treatment increased these levels in both transgenic as well as in the hypothalamic ventromedial and paraventricular nuclei of control mice. 5-HT2A receptor mRNA levels were similar in hippocampal CA1 and CA2 subregions of control and transgenic, but were lower in the CA3 and CA4 subregions of transgenic mice. Fluoxetine had no effect on 5-HT2A mRNA levels of transgenic mice but reduced control mouse 5-HT2A receptor mRNA levels in the CA3 subregion. These results suggest that impaired glucocorticoid receptor function can affect hippocampal 5-HT2A receptor expression in transgenic mice and that this is not corrected by fluoxetine treatment.

Animals↗
PubMed1993

Identification and immunolocalisation of annexins V and VI, the major cardiac annexins, in rat heart.

OBJECTIVE: The heart contains proteins of the annexin family, a unique group of calcium binding proteins. This study was aimed at identifying the major cardiac annexins and determining their distribution in the rat heart. METHODS: Annexins were isolated by affinity chromatography and purified by ion exchange high pressure liquid chromatography. Identification of isolated proteins by immunoblotting was confirmed by partial amino acid sequence determination. Antisera raised against the isolated proteins were used for immunohistochemistry by the avidin-biotin-peroxidase technique. RESULTS: Two annexins were isolated and purified. Amino acid sequencing confirmed their identities as annexin V and VI. Immunohistochemistry showed that both annexins were present in cardiac myocytes and non-myocytes, but a distinct pattern of distribution was seen for each annexin. Annexin V immunoreactivity was enhanced in the atria compared with the ventricles, whereas annexin VI was more uniformly distributed. In individual cardiac myocytes annexin V was distributed throughout the cell by contrast with annexin VI, which localised to the sarcolemma. Intercalated discs displayed immunoreactivity for both annexins, most prominently for annexin VI. The most striking immunoreactivity for annexin V occurred in vascular endothelial cells, both in the microcirculation and in the major coronary vessels. Immunoreactivity for annexin VI in vascular structures was localised to the nuclei of endothelial and smooth muscle cells. CONCLUSIONS: Annexins V and VI are the major cardiac annexins. The localisation of these annexins to different components of cardiac myocytes will serve to direct the search for their functions in the heart. The striking immunoreactivity for annexins, particularly annexin V, in the coronary vessels indicates that the functions of cardiac annexins include a role in the coronary circulatory system.

Amino Acid Sequence↗
PubMed1992

Rat brain natriuretic peptide is localized in atrial granules and released into the circulation.

Rat brain natriuretic peptide (BNP) was detected by radioimmunoassay in heart atria and ventricles and in plasma. We have investigated its localization in atria and the possibility of cosecretion of atrial natriuretic factor (ANF) and BNP into the circulation. BNP was detected by chromatographic analysis and immunoblotting in the isolated atrial granules together with ANF: It consisted of two immunoreactive proteins of 14,000 and 2,500 apparent molecular weight. By immunohistochemical methods, BNP was particularly found in the perinuclear region of atrial cardiocytes. Double-labeling immunocytochemical methods colocalized BNP and ANF in the same atrial secretory granules. Basal plasma BNP levels ranged from 2.6 to 4.4 fmol/ml. After stimuli by morphine injection or an aortocaval shunt, BNP levels increased by 4- and 7-fold, respectively, whereas ANF levels rose by 50- and 6-fold, respectively. Depending on the stimulus, BNP release into the circulation is not necessarily proportional to ANF, indicating that BNP may originate not only from the atrial granules but also from other tissues such as the ventricles. These results suggest that BNP may participate with ANF in blood pressure control and salt and water homeostasis.

Animals↗
PubMed1989

Atrial natriuretic factor in the impulse-conduction system of rat cardiac ventricles.

A complex network of atrial natriuretic factor-producing cells has been delineated by biochemical and morphological techniques in the rat ventricular myocardium. The chordae tendineae spuriae (CTS; false tendons) contain ANF mRNA and the ANF propeptide (Asn 1-Tyr 126) as assessed by Northern blot analysis, high-pressure liquid chromatography and immunohisto- and -cytochemistry, using three different affinity-purified antibodies: monoclonal and polyclonal antibodies against C-terminal ANF (Arg 101-Tyr 126) and polyclonal antibodies against N-terminal ANF (Asp 11-Ala 37). Two types of cells harboring ANF-containing secretory granules constitute the CTS: the majority (Purkinje type I) have ultrastructural similarities with both atrial and classical Purkinje fibers. Purkinje type-II fibers resemble working ventricular cardiocytes. Both cell types harbor a large paranuclear Golgi complex. The subendocardial Purkinje network is also made up of these two cell types. In this location, Purkinje type-I fibers form cable-like structures while Purkinje type-II fibers are either located beneath the former or abut directly on the endocardium. The latter are not separated from adjacent working ventricular cardiocytes by connective tissue septa. Coronary arteries and arterioles, as in birds, are surrounded by a cushion of Purkinje type-II fibers which blend with the surrounding myocardium. These results indicate that, in the rat, the entire intraventricular conduction system is constituted of endocrine cells producing ANF.

Animals↗
PubMed1989

Atrial natriuretic factor in Purkinje fibers of rabbit heart.

The Purkinje fibers of the rabbit false tendons (chordae tendineae spuriae) are endocrine cells containing immunoreactive atrial natriuretic factor (ANF) and ANF messenger RNA (mRNA). These cells, as visualized by immunocryoultramicrotomy, contain immunoreactive ANF in their secretory granules and their Golgi complex and exhibit ANF mRNA, as visualized by in situ hybridization with an ANF complementary RNA probe. The content of immunoreactive ANF and ANF mRNA of the Purkinje fibers is midway between that of atrial and ventricular working cardiocytes. High-pressure liquid chromatography analysis of immunoreactive ANF using antibodies against the C-terminal and N-terminal moieties of the molecule indicates that part of immunoreactive ANF contained in Purkinje fibers is the propeptide [Asn1,Tyr126]ANF whereas part was nonspecifically cleaved into C-terminal and N-terminal ANF. The chordae tendineae spuriae exhibit binding sites for ANF (Kd:approximately 1.0 nM; Bmax:approximately 2.3 fmol/mg). ANF profoundly decreases basal and stimulated (epinephrine, dopamine, isoproterenol, and forskolin) adenylate cyclase activity and cyclic adenosine monophosphate (AMP) levels. ANF has little effect on norepinephrine-stimulated adenylate cyclase activity or on norepinephrine-stimulated cyclic AMP levels. ANF produces only a slight increase in guanylate cyclase activity and cyclic guanosine monophosphate levels at high (10(7)-10(6) M) concentrations. These results suggest an autocrine function for ANF in the modulation of the impulse in the peripheral conduction cells (Purkinje fibers) of the rabbit through changes in second messenger levels.

Animals↗
PubMed1989

Ventricles as a major site of atrial natriuretic factor synthesis and release in cardiomyopathic hamsters with heart failure.

The aim of the present study was to correlate in cardiomyopathic hamsters with congestive heart failure the levels of atrial and ventricular atrial natriuretic factor (ANF) messenger RNA (mRNA) with immunoreactive ANF (IR-ANF) plasma levels and the relative amount of IR-ANF released by the whole heart versus isolated ventricles in the Langendorff preparation. High-performance liquid chromatography analysis of the forms of ANF present in plasma and in the Langendorff effluent of whole heart versus isolated ventricles was also performed. As previously found for cardiac IR-ANF, the levels of ANF mRNA decreased gradually in atria and increased in an analogous fashion in ventricles with the severity of congestive heart failure. Plasma IR-ANF levels (C-terminal) were more elevated in moderate than in severe congestive heart failure, as were the IR-ANF levels in the Langendorff effluent of the whole heart. On the contrary, the effluent of isolated ventricles from animals in severe heart failure yielded more IR-ANF than that from hamsters in moderate heart failure. Thus, while the isolated ventricles from controls contributed 35.8% of IR-ANF released by the whole heart, ventricles from hamsters in moderate heart failure contributed 17.5%, and those from hamsters in severe heart failure contributed 73.9%. These results indicate that atrial cardiocytes contribute more IR-ANF than their ventricular counterpart in moderate heart failure and that ventricles are a major source of plasma IR-ANF in severe heart failure. Analysis of IR-ANF from plasma and the Langendorff effluent from whole hearts and isolated ventricles revealed that the ventricles are the major source of the propeptide (and of its cleaved products) found in the circulation of cardiomyopathic hamsters. These results suggest that ANF synthesis and secretion do not increase conjointly in atria but do increase in ventricles during congestive heart failure.

Animals↗
PubMed1988

Validity and reliability issues in alternative patient classification systems.

The validity and reliability issues involved in using alternative patient classification systems were reviewed. Disease Staging and Patient Management Categories (PMCs) were applied separately and in conjunction with DRGs to three populations of patients drawn from a nine-hospital community data base. Data were examined with analyses that were as consistent as possible with hospital-based reviews of resource utilization. Questions focused on content and context validity (partially assessable by homogeneity), general and statistical reliability (measured by variance reduction), gaming, and cost. Ordinal stratifications were inconsistently produced, and improvement to DRGs' homogeneity was generally negligible. When used alone, staging produced only half the variance reduction of DRGs. PMCs, when used alone, appeared to produce sizeable variance reductions that may have been due to the large number of one- and two-case categories produced. Staging had category overlap, was expensive, and was unidimensional and subject to manipulation. PMCs had potentially serious logic problems, and both were inadequately documented. Neither system was considered appropriate for all needs, but each might work adequately under well-defined and limited conditions.

Diagnosis-Related Groups↗
PubMed1987

A murine monoclonal antibody against rat atrial natriuretic factor (ANF) which cross-reacts with mouse ANF.

A monoclonal antibody (MAb), 2H2, against rat synthetic atrial natriuretic factor (ANF) (Arg101-Tyr126) recognizes native ANF related peptides. The lack of reactivity of 2H2 with amino-terminal truncated ANF peptides implicates the two amino terminal arginine residues of ANF in the 2H2 epitope. Similarly, poor immunoreactivity of human ANF indicates the participation of isoleucine 110. Arginines 101 and 102 and isoleucine 110 may thus participate in a conformational epitope recognized by 2H2 or alternatively, substitution for, or elimination of these residues may alter the conformation of the 2H2 epitope. The MAb shows little cross-reactivity with extracts of rabbit atria but recognizes ANF related peptides in mouse and hamster atrial extracts. 2H2 also identifies immunoreactive ANF in histological sections of rat, mouse and hamster atria.

Animals↗
PubMed1986

Internalization and lysosomal association of [125I]angiotensin II in norepinephrine-containing cells of the rat adrenal medulla.

The morphological localization of [125I]angiotensin II (AII) in the rat adrenal medulla (AM) was studied by light- and electron-microscopic radioautography in vivo. With light microscopy the presence of binding sites for AII in both norepinephrine-containing (NE) and epinephrine-containing (E) cells was confirmed. With electron microscopy, it was found that AII binds to the cell surface of NE cells, is progressively internalized, and is associated with lysosomes and Golgi complex within 20 min, whereas in E cells AII seems to be internalized earlier and recycled back to the cell surface within 5 min without any appreciable association with intracellular organelles. These results suggest different intracellular pathways for AII in NE and E cells of the rat AM.

Adrenal Medulla↗
PubMedDate not supplied

Effects of in ovo exposure to 2,3,7,8-TCDD on F1 generation adult chickens (Gallus gallus).

White Leghorn chickens (Gallus gallus) were used as surrogate species for the resident wild turkeys found on the Times Beach, Missouri, Superfund site. Parental chickens were injected with concentrations of 2,3,7,8-TCDD which modeled soil concentrations before (200 ppb) and after remediation (1ppb)[1]. Offspring were followed through development to assess alterations in reproductive maturity through the use of a four-way breeding study. F1 adult females exposed to a maternal dose of 8.6 ng/day began egg production approximately two weeks later than did F1 control adult females. By week eight, however, egg production between groups was equivalent. No differences were observed in eggshell gland estrogen or progesterone receptor levels.

Animals↗
PubMedDate not supplied

Effects of environmentally relevant concentrations of 2,3,7,8-TCDD on domestic chicken immune function and CYP450 activity: F1 generation and egg injection studies.

Domestic chickens (Gallus gallus) were used as a surrogate species for wild turkey to assess risk from environmental 2,3,7,8-TCDD exposure. Lymphocyte proliferation and CYP450 induction were assessed in adults exposed via i.m. injection, in F1 14-day old hatchlings, in F1 adults (30-weeks old), and in 14-day old hatchlings exposed via yolk sac injections. Hatchlings from injected eggs exhibited a dose-response in lymphocyte proliferation, IgM titers, EROD, and PROD endpoints. Exposed adults showed a significant dose-dependent increase in CYP450 induction. F1 14-day old chicks exhibited a significant dose-dependent suppression of B-cell proliferation and induction of CYP450 enzymes. F1 adult proliferative responses exhibited B-cell suppression, that was not statistically significant. Significant sex-dependent EROD and MROD induction was also observed in F1 adults, indicating mixed-function oxidase imprinting from maternal exposure.

Animals↗