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Biomedical subjects

J A Grimaud

Publications and source records attributed to J A Grimaud.

At least 19 recordsLinked to original sources
PubMed2001

Mechanical properties and structure of carotid arteries in mice lacking desmin.

OBJECTIVE: Our aim was to determine in desmin homozygous mutant mice the viscoelastic properties, the mechanical strength and the structure of the carotid artery. METHODS: To assess the viscoelastic properties of large arteries, we have performed an in vivo analysis of the diameter-, and distensibility-pressure curves of the common carotid artery (CCA) in homozygous (Des -/-), heterozygous (Des +/-) and wild-type (Des +/+) mice. To evaluate the mechanical strength, we have measured the in vitro intraluminal pressure producing the rupture of the carotid artery wall. The structure analysis of the arterial wall was based on histology and electronic microscopy. RESULTS: A lower distensibility and an increase of arterial wall viscosity were observed in Des -/- compared with Des +/+. Arterial thickness of Des -/- was similar to those of Des +/+, without changes in elastin and collagen contents. Electron microscopy revealed that the perimeter of cellular fingerlike-projections was smaller in Des -/-, indicating that the cells have lost part of their connections to the extracellular matrix. The rupture pressure was significantly lower in Des -/- (1500+/-200 mmHg) compared with Des +/+ (2100+/-80 mmHg) indicating a lower mechanical strength of the vascular wall. No significant difference was found between Des +/- and Des +/+. CONCLUSION: The desmin is essential to maintain proper viscoelastic properties, structure and mechanical strength of the vascular wall.

Analysis of Variance↗
PubMed2001

Schistosomiasis mansoni and viral B hepatitis in woodchucks.

BACKGROUND/AIMS: An interaction between human schistosomiasis and viral hepatitis B has often been suggested, but never established. The experimental investigation has been hampered by the lack of a suitable model. Only woodchucks are susceptible to both Schistosoma mansoni and a B-like hepatitis virus (WHV) infections. This study explores the relevance of this unique model regarding hepatitis/schistosomiasis interactions. METHODS: Woodchucks (Marmota monax and Marmota marmota) were infected with: (a), S. mansoni; (b), WHV; or (c), both S. mansoni and WHV. RESULTS: Following the experimental parasitic infection of woodchucks, with or without WHV, schistosomiasis presented a peculiar and severe course in early infection, involving mostly the intestines. Subsequently, the intestinal and hepatic lesions underwent considerable modulation and the periovular granulomas decreased in size and number, while the parasitic infection tended to self-cure within the 9 months following infection. Nine woodchucks inoculated with the hepatitis virus alone presented with several degrees of acute and chronic hepatitis, with one of them dying of hepatocarcinoma 1 year after inoculation. Four woodchucks with concomitant viral and schistosome infections presented with a simple additive pattern of lesions, without any evidence of modification or aggravation of either one of the two infections. Similarly, no significant impact of schistosomiasis on WHV serum markers could be seen. CONCLUSIONS: Schistosomiasis and viral hepatitis in woodchucks run parallel courses, with neither apparent special histological features derived from the association of the two conditions, nor modulation of WHV replication. Schistosomiasis itself, however, was observed to run a peculiar course in the woodchuck. The present data are important for consideration in further experiments exploring the interplay between schistosomiasis and viral hepatitis induced liver damage in this unique experimental host.

Animals↗
PubMed2001

Raising the social yield of research: challenge facing biotechnology.

The biological revolution is the latest in a series of scientific revolutions that have ushered in a new era in physics, chemistry, industry, and composite materials. The latest instruments of life - bioengineering for and by the living - challenge mankind with a number of fundamental questions, while offering an unprecedented series of opportunities. Alternative biotechnologies, biological agriculture for the environment, genomics applied to preventive medicine, genetic engineering are just a few of the benefits mankind may reap from bioengineering. Modern society demands more knowledge, and it is up to public authorities to invest in outreach programs to make public the latest scientific activities and findings. In the case of biotechnologies, it is particularly true that the product of research is not complete until its benefits are returned to society.

Animals↗
PubMed1999

Long-term administration of interferon-alpha in non-responder patients with chronic hepatitis C: follow-up of liver fibrosis over 5 years.

In chronic hepatitis C, previous data have shown that short-term treatment with interferon-alpha (IFN-alpha) can reduce collagen deposition in the liver independently of the viral response. The aim of this work was to determine, in non-responder patients, the long-term effect of IFN-alpha on liver fibrosis according to the total administered dose and the fibrotic stage. Fibrosis was investigated on liver biopsies from 24 non-responder patients with chronic hepatitis C retreated with successive courses of IFN-alpha. The degree of liver fibrosis was assessed on three successive biopsies, performed before IFN-alpha treatment and 1 and 5 years later, in 13 and 11 patients, respectively, treated for less (mean: 7.5 months, 313 MU) and more (mean: 21.8 months, 791 MU) than 1 year. For each biopsy, fibrosis was assessed using a histological semiquantitative fibrosis scoring system and by morphometry after picrosirius red staining. Regardless of the dose and duration of IFN-alpha therapy, a slight decrease of fibrosis was observed in patients 5 years after starting treatment. In cirrhotic patients, a short treatment induced an improvement followed by a relapse of fibrosis in 57%, and only 43% of patients showed constant collagen regression over the 5 years of follow-up. On the contrary, after prolonged therapy, a progressive and significant decrease occurred throughout the follow-up period in all patients (P = 0.045). Long-term treatment with IFN-alpha is therefore associated with regression of liver fibrosis, particularly in cirrhotic patients. These promising results need to be confirmed in a larger series of patients.

Adult↗
PubMed1998

Liver fibrosis in unisexual murine Schistosomiasis: quantitative study and morphological changes in mice with chronic infection.

The main complication of Schistosomiasis is the development of liver fibrosis as a result of periovular granuloma in portal tract. This study was undertaken to evaluate the role of the worms in the liver, using the unisexual murine schistosomiasis model. Hepatic fibrosis and histopathological lesions were sequentially followed for 65 weeks in mice experimentally infected with male Schistosoma mansoni. Morphological study revealed that, from the 25th week post-infection, a diffuse fibrosis affected the main branches of the portal vascular system following the host inflammatory reaction, associated with the proliferation of myofibroblasts in situ. Quantitative methods confirmed that an increase of fibrotic deposit occurred during chronic unisexual infection from 25 to 50 weeks post-infection, as compared to controls (35.06 +/- 3.55% versus 27.41 +/- 2.56%) suggesting that antigenic substances secreted by adult schistosomes, in the absence of any eggs, might initiate periportal and perisinusoidal fibrous reaction. The cytokine production and the evolution of inflammation towards fibrosis involves stellate cells and myofibroblasts stimulation. This fibrotic process consequently traduces a reparative phenomenon of the liver.

Actins↗
PubMed1997

Human interleukin 4 is a glycosaminoglycan-binding protein.

Using different binding assays we examined the interaction of the cytokine interleukin 4 (IL-4) with basement membrane. Equilibrium binding analysis revealed a high-affinity site characterized by a dissociation constant (Kd) of 0.3 nM. This interaction was confirmed by native polyacrylamide gel electrophoresis, which also indicated that the binding sites are composed of glycosaminoglycans (GAGs). In competition studies, N-sulfated GAGs (heparin and heparan sulfate) displayed a higher affinity than other GAGs for IL-4, and therefore may constitute the physiological ligand. Furthermore, the enzymatic and chemical cleavage of heparan sulfate demonstrated that only few peculiar domains (i.e. N-sulfated rich sequences) within heparan sulfate chains, displayed a significant affinity for IL-4. These data indicate a possible role of GAGs in storing IL-4 and modulating the cellular response to this cytokine.

Basement Membrane↗
PubMed1997

Lobular--but not periovular--inhibition of collagen deposition in the liver of S. mansoni infected mice using interferon-gamma.

BACKGROUND/AIMS: Interferon-gamma (IFNgamma) elicits antiproliferative and antifibrogenic activity in a variety of mesenchymal cells, including hepatic stellate cells (Ito cells), and therefore represents a possible drug for liver fibrosis. However, IFNgamma binds to heparan sulfate, and is localized by these molecules in a restricted area within the tissue. For example, in rat liver, it has been shown that following injection, IFNgamma was concentrated in a restricted area by heparan sulfate. The aim of this study was to analyze, at the tissular level in the liver, the antifibrogenic activity of IFNgamma. METHODS: Chronic inflammation due to Schistosoma infection induces hepatic fibrogenesis around the parasite eggs (portal fibrosis) and in the parenchyma (lobular fibrosis). Infected mice were treated with recombinant IFNgamma, and the collagen content of the liver was evaluated by means of biochemical dosages, histologic and morphometric examination of liver tissue, and electron microscopic analysis. RESULTS: IFNgamma reduced the whole liver collagen content by 28% compared to control mice. In control mice, collagen was found around eggs and infiltrating the parenchyma, associated with a diffuse array of inflammatory cells, while in treated mice the collagen was present only around eggs and surrounded by a dense layer of inflammatory cells. Therefore, collagen was measured in isolated granulomas and in the remaining parenchyma. We found that IFNgamma strongly reduced the parenchymal collagen (74%), but had no effect on the granuloma collagen content. CONCLUSIONS: Together these data demonstrate that IFNgamma did not act in a homogeneous manner in the liver. Since granulomas are almost completely devoid of heparan sulfate, these data could suggest, among others hypotheses, that heparan sulfate which binds IFNgamma either localizes or mediates the cytokine activity outside the granulomas.

Animals↗
PubMed1997

Lysyl oxidase gene expression in the stromal reaction to in situ and invasive ductal breast carcinoma.

Lysyl oxidase is involved in the main pathway of collagen and elastin cross-linking: it has a role in the maturation of fibrillar matrix proteins in fibrosing processes and dictates their stability against metalloproteases. The stromal reaction patterns in ductal breast carcinoma are known to be morphologically varied. This has raised the hypothesis that there might be a differential expression of the lysyl oxidase gene as a function of stromal reaction pattern. The present study investigates this potential correlation and the role of matrix protein cross-linking in stromal differentiation. Lysyl oxidase was detected by immunohistochemistry and lysyl oxidase gene expression by in situ hybridization. Maximal expression was observed in myofibroblasts and myoepithelial cells around in situ tumors and in the reactive fibrosis facing the invasion front of infiltrating tumors. The lysyl oxidase substrates were observed in parallel, resulting in the stabilization of a scar-like peritumor barrier. In contrast, a lack of lysyl oxidase was associated with the loose or scirrhous stroma accompanying invading tumors; here, in situ hybridization revealed type I collagen synthesis, resulting in the deposition of non-cross-linked matrix proteins susceptible to degradation. The early development of a cross-linked matrix around ductal breast carcinoma suggests a possible bost defense mechanism, whereas the synchronous or late stromal reaction lacking lysyl oxidase favors tumor dispersion.

Breast↗
PubMed1997

Quantitative studies on liver fibrosis and alpha-smooth muscle actin expression in heroin abusers.

Lobular hepatic fibrosis and the presence of myofibroblasts were studied in heroin abusers, by quantitative automatic image analysis. Nineteen addicts (DA) and thirteen patients having stopped consumption (exDA) were compared to a non-addict group (CONTROL). Addicts, all anti-HIV and HBsAg negative, showed increased transaminase levels. Hepatitis C markers were ot available, at the time of biopsy. The surface of the centrolobular fibrosis, measured on picrosirius stained slides, was respectively 1.9 and 3.5 times larger in DA and exDA than in CONTROL (p < 0.0001). Immunolabelling with an alpha-smooth muscle actin antibody (alpha-SMA) revealed stellate cells in a perisinusoidal location, mainly in areas of matrix thickening in the space of Disse. Morphometric analysis of alpha-SMA expression showed significant differences between the three groups of patients, p < 0.0001 (CONTROL: 198.06 +/- 5.59 microns2; DA: 2227.91 +/- 88.02 microns2; exDA: 3469.10 +/- 154.98 microns2). The surface density of collagen and of alpha-SMA reactivity was also significantly different between these groups (p < 0.0001). These data strongly suggest that heroin is responsible for an early and progressive centrolobular liver fibrosis, occurring simultaneously with a myofibroblastic response. It might represent a reparative phenomenon arising from a direct vascular injury, leading to an impairment of blood-hepatocyte exchange.

Actins↗
PubMed1996

Interferon gamma differentially affects the synthesis of chondroitin/dermatan sulphate and heparan sulphate by human skin fibroblasts.

Interferon gamma (IFN gamma) is often considered to be an antifibrotic cytokine because it inhibits collagen synthesis in fibroblasts. Here we report the effects of recombinant human IFN gamma on sulphated glycosaminoglycan chains produced by normal skin fibroblasts from adult donors. IFN gamma (250 i.u./ml) induced an increase in incorporation of D-[1-3H]glucosamine into glycosaminoglycans, either secreted into the culture medium or associated with the cell layer. The structures of these molecules were analysed by using various cleavage agents (heparinases I and II, heparitinase/chondroitinases ABC and AC/periodate oxidation) followed by size-exclusion and anion-exchange HPLC. No modification was detected in the structure of the heparan sulphate chains. In contrast, the cytokine induced changes in the microcomposition of chondroitin/dermatan sulphate chains. More precisely, we found a decrease in the iduronic acid content, associated with down-regulation of the 4-O-sulphation on the GalNAc residues. In contrast, the 6-O-sulphation on these GalNAc residues was potentiated by the cytokine. These results indicate that IFN gamma is able to modulate not only collagen but also the structure of galactosaminoglycans synthesized by human skin fibroblasts.

Adult↗
PubMed1996

Heparin decreases the blood clearance of interferon-gamma and increases its activity by limiting the processing of its carboxyl-terminal sequence.

Interferon-gamma (IFN-gamma) binds with high affinity to heparan sulfate and heparin molecules through its carboxyl-terminal domain. In vivo, IFN-gamma is eliminated from the bloodstream with a half-life (t1/2) of 1.1 min, due to binding to heparan sulfate. Unbound IFN-gamma is cleaved rapidly at the carboxyl-terminal side, a process that removes at least 18 amino acids and inactivates the cytokine. When bound to heparin, the plasma clearance of IFN-gamma is decreased greatly (t1/2 = 99 min), and the area under the curve obtained with IFN-gamma alone represented only 15% of that obtained with injected IFN-gamma bound to heparin. Furthermore, the binding of heparin to IFN-gamma limits the extent of its carboxyl-terminal domain degradation to less than 10 amino acids. Importantly, this process increases the cytokine activity by as much as 600%. These data demonstrate that the blood clearance of the cytokine is a non-receptor-mediated process and that in vivo the local concentration of heparan sulfate/heparin-like molecules regulates IFN-gamma activity by a unique mechanism involving a controlled processing of its carboxyl-terminal sequence.

Animals↗
PubMed1996

Interferon-gamma inhibits 35S incorporation in heparan sulfate synthesized by human skin fibroblasts.

Glycosaminoglycans synthesized by human skin fibroblasts were simultaneously radiolabelled with D-[1-(3H)]glucosamine and Na2(35)SO4. Considering 3H incorporation, we found that IFNgamma increased the production of glycosaminoglycan synthesis, including hyaluronic acid, heparan and chondroitin/dermatan sulfate. In contrast, the production of heparan and chondroitin/dermatan sulfate was slightly decreased on the basis of the 35S signal. Furthermore, when heparan sulfate was treated with nitrous acid, the release of free 35S was greater in control than in treated cells, although the 3H patterns of depolymerization with this agent were similar. These data demonstrate that IFNgamma inhibits the incorporation of sulfate from extracellular medium into heparan sulfate.

Cells, Cultured↗
PubMed1996

The carboxy-terminal cross-linked telopeptide of type I collagen (ICTP) is a potential serum marker of ongoing liver fibrosis.

We report for the first time the measurement of the serum concentration of the carboxy-terminal cross-linked telopeptide of type I collagen in patients with various liver diseases. This breakdown product of type I collagen, which is the major collagen type found in fibrotic liver, was measured by a radioimmunoassay in the serum of 149 patients with various liver diseases and in 67 controls. Its concentration is significantly elevated (P < 0.05) above reference intervals in sera from patients with liver diseases, except in patients with chronic active hepatitis of unknown origin and in patients with acute hepatitis A. In the 143 patients with liver fibrosis, the serum level of the carboxy-terminal telopeptide of type I collagen is correlated with the extent of fibrosis, as assessed by a histological scoring system (r = 0.3899, P < 0.0001), but not with inflammation and necrosis.

Adult↗
PubMed1996

In situ detection of human cytomegalovirus DNA in gastrointestinal biopsies from AIDS patients by means of various PCR-derived methods.

The development of new in situ assessment of HCMV disease on endoscopical gastrointestinal biopsies from AIDS patients is described and compared with the viral load measured by semiquantitative solution-phase PCR (SQ-PCR). Ten biopsies were examined by viral isolation, standard histology, in situ hybridization (ISH), in situ PCR-hybridization (PCR-ISH) and SQ-PCR, using the same target sequence. The methods developed for in situ HCMV detection were HCMV primers, the plasmid pCMV 406-S, a vector-free-digoxigenin-labelled HCMV-362 probe and the pSK + MCS nonsense probe. Paraffin-embedded MRC5 cells, either HCMV-infected or uninfected served as controls of specificity for ISH. beta-Actin primers were designed as markers of DNA integrity. Computerized models of the PCR, solution-phase and in situ PCR on formalin-fixed DNA indicated that HCMV and beta-actin primers were efficient and specific. Nine biopsies were negative for HCMV by histology and virus isolation. SQ-PCR revealed 80,000; 80 and < 80 HCMV genomic equivalents in 6, 2 and 2 biopsies, respectively. In 8 biopsies, both ISH and PCR-ISH identified positive nuclei in the intestinal epithelium, with sparing of the lamina propria. This indicates that an improvement in in situ methods can help the timely diagnosis of HCMV infection. Direct in situ PCR with beta-actin primers showed a positive signal in all the nuclei in the tissue sections, whereas omission of Taq polymerase resulted in an absence of signal, implying optimal in situ PCR. The data suggest an early-stage reactivation of HCMV, possibly harboured in the intestinal epithelium.

AIDS-Related Opportunistic Infections↗
PubMed1996

Mechanism of collagen network stabilization in human irreversible granulomatous liver fibrosis.

BACKGROUND & AIMS: Cross-linking participates in the increased stability of collagen towards proteolytic degradation. Liver collagen cross-linking by pyridinoline, from the lysyl oxidase pathway, and by pentosidine, issued from glycation, was investigated to determine their respective contribution to collagen stabilization in patients with an irreversible liver fibrosis caused by the parasitic granulomatous disease alveolar echinococcosis. METHODS: Liver pyridinoline and pentosidine were analyzed by high-performance liquid chromatography, and urinary pyridinoline was analyzed by immunoassay. Cross-linked type I collagen was localized by immunohistochemistry with an antibody against the C-terminal part of the molecule, involved in pyridinoline formation, that was measured in serum by radioimmunoassay. RESULTS: In contrast to pyridinoline, pentosidine decreased in fibrotic lesions. Cross-linked I collagen was located predominantly in collagen bundles in the periparasitic granuloma. Serum pentosidine and urinary pyridinoline levels did not differ significantly from controls, but the serum concentration of the C-terminal telopeptide of type I collagen increased significantly. CONCLUSIONS: Lysyl oxidase-mediated cross-linking is the major process contributing to the stabilization of collagen in granulomatous fibrosis, and glycation is not significantly involved in it. The changes induced by alveolar echinococcosis in liver collagen metabolism are associated with an increase in serum C-telopeptide of type I collagen.

Amino Acids↗
PubMed1996

Distribution of hepatic glycosaminoglycans during acute schistosomiasis: modulation by IFN gamma treatment.

An important pathological outcome of schistosomiasis is hepatic fibrosis, with a significant deposit of collagens and proteoglycans. In this study, hepatic and granuloma-associated glycosaminoglycans (GAGs) were analyzed both quantitatively and qualitatively at the acute stage of murine infection with Schistosoma mansoni. The effects of IFN gamma, which has been successfully used for reducing collagen deposition in the liver during schistosomiasis, were also analyzed in granulomas and the surrounding liver parenchyma. Acute schistosomiasis resulted in a 4.4-fold increase in total hepatic GAG content, from which granulomatous GAGs--mainly chondroitin sulfates A/C and B--represented only one sixth of total GAGs amount. Therefore, the increase was found predominantly in the parenchyma. In this compartment, qualitative changes were also induced with a marked increase in the proportion of chondroitin sulfates A/C balanced by a decrease in the proportion of heparan sulfate and dermatan sulfate. IFN gamma reduced parenchymal GAG content by 47%. Qualitatively, the cytokine increased the proportion of heparan sulfate and reduced the quantity of chondroitin sulfates A/C by half in this compartment. By contrast, IFN gamma had neither quantitative nor qualitative effect on fibroinflammatory granulomas. In these structures, the absence of heparan sulfate--which is suspected to mediate IFN gamma activity--might explain these observations.

Animals↗
PubMed1995

Molecular organization of the interferon gamma-binding domain in heparan sulphate.

Interferon (IFN)-gamma, in common with a number of cytokines or growth factors, strongly interacts with heparan sulphate (HS). It has been shown previously that one of the C-terminal basic clusters of amino acids (a regulatory element of IFN-gamma activity) is involved in this interaction. The structural organization of the HS domain that binds to human IFN-gamma has been investigated here. IFN-gamma-affinity chromatography of HS oligosaccharides released by either enzymic or chemical cleavage showed that the binding site is not found in a domain that is resistant to either heparinase or heparitinase or exclusively N-sulphated or N-acetylated. This led us to take a 'footprinting' approach in which HS was depolymerized in the presence of IFN-gamma and the cytokine-protected sequences were separated from the digested fragments. Using this strategy we consistently isolated an IFN-gamma-protected domain (IPD; approx. 10 kDa) which displayed the same affinity as full-length HS for the cytokine. Treatment of IPD with either heparinase or heparitinase strongly reduced its affinity, confirming that the high-affinity binding site encompassed a mixture of HS structural domains. Patterns of depolymerization with either enzymic or chemical agents were consistent with IPD being composed of an extended internal domain (approx. 7 kDa) which is predominantly N-acetylated and GlcA-rich, flanked by small N-sulphated oligosaccharides (mainly hexa- to octasaccharides). This is the first description of an HS protein-binding sequence with this type of molecular organization. Furthermore, using a cross-linking strategy, we demonstrated that one HS molecule bound to an IFN-gamma dimer. Together these results lead us to propose a novel model for the interaction of HS with a protein, in which two sulphated terminal sequences of the binding domain interact directly with the two IFN-gamma C-termini and bridge the two cytokine monomers through an internal N-acetyl-rich sequence.

Animals↗