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S Peyrol

Publications and source records attributed to S Peyrol.

At least 37 records · Page 2Linked to original sources
PubMed1997

The isolated perfused porcine liver: assessment of viability during and after six hours of perfusion.

Isolated liver perfusion was developed for the study of liver physiology and preservation. The recent development of new perfusion devices and appropriate liver preservation solutions prompted us to reconsider liver perfusion for the specific purpose of evaluating viability in terms of biochemical changes, paying special attention to modifications in the histological ultrastructure. Twenty-two isolated pig livers were perfused with autologous blood. Arterio-portal perfusions were carried out using an extracorporeal perfusion circuit with a hollow fibre membrane oxygenator. Four groups of pig livers were studied using three different liver flushing solutions [Ringer's lactate, ELOHES, and University of Wisconsin (UW)] and two different oxygenation modalities. Liver function tests and histological studies were done. Our results revealed that a high partial oxygen pressure (PO2) level was deleterious to the ultrastructural elements of hepatocytes, in particular to the mitochondria. It was also associated with deficient metabolic performance, i.e., poor bile production and lack of aerobic metabolism. Normal blood gas values could be obtained with the use of air for liver oxygenation. Flushing of the liver with Ringer's lactate or a macromolecular solution such as ELOHES was associated with severe liver cell injuries, as reflected by a marked rise in liver enzymes and histological lesions. Satisfactory results were obtained when UW solution was used for liver harvesting. We conclude that an appropriate liver preservation solution, normal blood gas values, and normal physiological arterio-portal pressure and blood flow are essential for appropriate liver function with preservation of liver architecture and of hepatocyte ultrastructures. Total bilirubin in bile and Factor V are sensitive indicators of good liver function.

Animals↗
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

Expression of a Schistosoma mansoni 28-kilodalton glutathione S-transferase in the livers of transgenic mice and its effect on parasite infection.

Schistosomiasis is a debilitating tropical disease for which an effective vaccine is needed. A 28-kDa glutathione S-transferase from Schistosoma mansoni (Sm28GST) has been shown to induce protective immunity. Sm28GST possesses significant sequence identity to mammalian GST isoforms. In order to study self-reactivity in mice immunized with Sm28GST and the concomitant phenomena of immune tolerance and epitope suppression, as well as their consequences for the protective immunity induced by this vaccination, we developed transgenic (Tg) mice that express Sm28GST under the control of a part of the mouse transferrin gene promoter. A study of (P28)Tg mice showed that the expression of Sm28GST was strictly localized in pericentrolobular hepatocytes. No histological change, inflammatory infiltrates, or modification of seric L-aspartate: 2-oxoglutarate aminotransferase concentration was observed over an 18-month period, despite a cross-reactivity between Sm28GST and a mouse molecule of 30 kDa. The immunoglobulin G anti-Sm28GST response of (P28)Tg mice immunized with recombinant Sm28GST was lower (P < 0.001) than that observed in non-(P28)Tg littermates and inversely proportional of Sm28GST liver expression. The response of non-(P28)Tg mouse spleen cells to Sm28GST stimulation was greater (P < 0.01) than that observed with (P28)Tg mouse spleen cells. (P28)Tg mice infected with 40 S. mansoni furcocercariae harbored more worms (P < 0.05) than did non-(P28)Tg control mice. The increase in the level of infection in (P28)Tg mice was reflected in concomitant increases in the numbers of adult worms and schistosome eggs found in livers and intestines after whole-body perfusion at 56 days postinfection, but no relative increase in the fertility of individual female worms was observed. The results obtained argue for the involvement of Sm28GST in reducing levels of infection and support the view that this enzyme has a central role in the maintenance of parasite viability, at least during its migration through host tissues.

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↗
PubMed1996

Ultrastructural aspects of Plasmodium falciparum-infected erythrocyte adherence to endothelial cells of Saimiri brain microvasculature.

We have recently shown that some squirrel monkeys (Saimiri sciureus) develop cerebral malaria when experimentally infected with asexual blood stage forms of different Plasmodium falciparum isolates. Since cerebral malaria is neither an inconsistent nor predictable event, several clones of endothelial cells isolated from the squirrel monkey brain microvasculature have been developed. Infected red blood cell (IRBC) adherence involved the knobs and direct membrane interactions through pseudopodes and microvilli on the Saimiri brain endothelial cell (SBEC) surface, similar to that observed with both brain microvascular endothelial cells from a patient who died of cerebral malaria and the rhesus monkey/P. coatneyi cerebral malaria model. The involvement of pseudopodes and microvilli increase the endothelial cell surface for the attachment of IRBCs; however, they are already present before the SBECs are exposed to IRBCs. With some SBEC phenotypes, embedding of IRBCs into the cytoplasma membrane of the endothelial cell was observed, resulting in an extremely close apposition of both SBEC and IRBC membranes during the adherence process. Once IRBCs are adherent, particularly for the embedding type, heterocellular communication-like structures between the cells become apparent. The upregulation of CD36 and intercellular adhesion molecule-1 by soluble recombinant (sr)-tumor necrosis factor-alpha or sr-interferon-gamma did not modify the IRBC interactions with SBECs at the ultrastructural level. The study shows further that the observed differences of IRBC adherence are due to unidentified phenotypic differences of SBECs rather than to a parasite isolate or particular endothelial cell receptor-associated phenomenon. Exploring P. falciparum IRBC cytoadherence in the squirrel monkey using a homologous physiologic target cell model in vitro should be useful for the evaluation of vaccine strategies and drugs to prevent human cerebral malaria.

Animals↗
PubMed1995

Isolation and characterization of brain microvascular endothelial cells from Saimiri monkeys. An in vitro model for sequestration of Plasmodium falciparum-infected erythrocytes.

The adhesion of parasitized red blood cells (PRBC) to the endothelium (sequestration) may contribute to the pathogenic events in severe human malaria caused by P. falciparum. However, the factors involved in the pathophysiology, especially cerebral malaria are poorly understood. Previously, we have shown that the squirrel monkey Saimiri sciureus is a potential model for human cerebral malaria. In this paper we describe five stable clones of endothelial cell lines isolated immediately postmortem from different regions of the brain of Saimiri monkeys. The endothelial cell characteristics of these clones were confirmed by analyzing their ultrastructural aspects by transmission electron microscopy and by immunodetection of various endothelial cell markers. The Saimiri brain endothelial cell clones (SBEC) varied in their expression of different surface molecules. For example, various combinations of receptors involved in P. falciparum PRBC adherence such as CD36, ICAM-1 and E-selectin, were expressed at baseline values and could be up-regulated by human srTNF-alpha and human srIFN-gamma. One of the SBEC clones showed a strong cytoadherence for various laboratory strains of P. falciparum despite the absence of surface expression of any of the known endothelial receptors implicated in PRBC adherence. This finding suggests the existence of a new and uncharacterized PRBC binding receptor. The use of target organ specific endothelial cell lines expressing a number of different potential P. falciparum PRBC cytoadherence receptors, will be a useful in vitro system for the evaluation of strategies for the development of vaccine and antimalarial drugs to prevent human cerebral malaria.

Animals↗
PubMed1995

Fibrosing vasculitis in Wegener's granulomatosis: ultrastructural and immunohistochemical analysis of the vascular lesions.

This study of two cases of pulmonary Wegener's granulomatosis (WG) focuses on the ultrastructural aspects of the vascular wall injury and on the immunohistochemical characterization of the perivascular connective matrix. The iterative waves of endothelial cell necrosis and regeneration are demonstrated by the multilamellar appearance of the basal lamina. Neutrophils infiltrate the vessel wall and myofibroblasts are recruited to injured vessels. The perivascular connective matrix associates basement-membrane like and fibrillar material with fibrin deposits. The initiation of the fibrosing process was assessed by the visualization of matrix molecules involved in targeting (p-fibronectin), organizing (cellular fibronectin and tenascin) and stabilizing (lysyl-oxidase) the fibrogenic activity. These elementary lesions affect different levels of the vascular tree, and capillaritis is involved in the extension of the pathological process. Lysyl-oxidase labelling reveals the fibrosing front which is located on the border of dense fibrosis. The markers of fibrosing activity disappear in the areas of fibrosis following vasculitis and/or ischaemic necrosis and/or granulomatosis. Vasculitis plays a major role in both the genesis and progression of the fibrosis observed in the late stage of WG.

Arteries↗
PubMed1995

[Spontaneous colonic perforations revealing Ehlers-Danlos syndrome type IV].

BACKGROUND: The malignant form of Ehlers-Danlos syndrome type IV owes its bad reputation to a proneness to spontaneous rupture of bowel or large vessels, which may reveal the disease. CASE REPORT: A girl suffered acute rupture of the sigmoid at the age of 5 years and rupture of the left colon, twice, at the age of 11 and 13 years, respectively. These ruptures required colostomy and finally colectomy. A proneness to bruisability, history of dislocation of hips, hypermobile joints, ovarian cysts and some minor abnormalities of her face resembled that of the Ehlers-Danlos syndrome which was confirmed by optic and electronic microscopy of the skin biopsy. CONCLUSION: This is the youngest case of rupture of bowel reported in Ehlers-Danlos syndrome. Long-term prognosis is influenced by repetition of intestinal ruptures and occurrence of vascular complications.

Child, Preschool↗
PubMed1995

Long-term cultured CD40-activated B lymphocytes differentiate into plasma cells in response to IL-10 but not IL-4.

We compared the effects of IL-10 and IL-4 on the functions of B lymphocytes triggered through their CD40. During the initial phase, IL-10 was as potent as IL-4 in inducing the expansion of viable B cells. Then, cellular expansion slowed down and after approximately 3 weeks the number of B cells started to decline. While the combination of IL-10 and IL-4 was synergistic during the first 2 weeks of culture, B cell recovery declined after 3 weeks, indicating that IL-10 prevails over IL-4. Those effects were not restricted to a specific B cell subset as both sIgD+ B cells and sIgD- B cells behaved in a similar way, though the latter population responded with a slightly accelerated kinetic. Inverted microscope examination and scanning electron microscopy showed that in response to IL-10, CD40-activated B cell cultures were heterogeneous with loose aggregates of cells as well as free floating large ovoid cells. In contrast, in the presence of IL-4, CD40-activated B cell cultures were essentially composed of tight cell clumps. IL-10 progressively induced all B cells to differentiate into non-replicating cells with intracytoplasmic Ig that secreted Ig at a high rate. Cytologic analysis indicated that IL-10 cultured cells display a basophilic cytoplasm with an arcoplasm and a low nucleus/cytoplasm ratio. Transmission electron microscopy demonstrated that when IL-10 was added to the culture, B cells displayed structures for excretion with extended endoplasmic reticulum and dilated cisternae containing paracrystalline structures, typical of plasmablasts cells. Taken together, these results indicate that IL-10 acts as a plasma cell differentiation factor for CD40-activated B cells.

Antibody-Producing Cells↗
PubMed1995

[Fatal acute silicosis caused by voluntary inhalation of scouring powder].

We report a case of acute fatal fibrosing silico-proteinosis occurring in nine months in a young woman who had voluntarily inhaled scouring powder. We recall the reports in the literature of the subacute or chronic forms associated with systemic diseases occurring after such inhalational practices. We recall the need for specific questioning and to complete the study, the need for microscopy and electron-microscopy associated with X-ray defraction, either on the alveolar lavage fluid or on a lung biopsy.

Acute Disease↗
PubMed1993

Granulomatous reaction and tissue remodelling in the cutaneous lesion of chromomycosis.

The cell-mediated immune reaction was studied in the cutaneous lesion of chromomycosis, using monoclonal antibodies against polymorphonuclear neutrophils, macrophage and lymphocyte subsets, endothelial and fibroblast cells. In addition, immunostaining of the main degradative enzymes (neutrophil elastase and interstitial collagenase) and certain important cytokines (transforming growth factor-beta, tumour necrosis factor-alpha and interferon-gamma) suggested an explanation for the granulomatous reaction and the associated tissue remodelling. The distribution pattern of neutrophils and macrophage subsets, observed by computer-aided image analysis, suggests that the in situ persistence of fungi is the main pathological factor.

Antigens, CD↗
PubMed1993

Transient expression of lysyl oxidase by liver myofibroblasts in murine schistosomiasis.

BACKGROUND: Murine schistosomiasis provides an experimental model of reversible fibrosis. The lysyl oxidase catalyzes the first step of collagen and elastin enzymatic cross-linking and appears to be a crucial factor in stabilizing the neosynthesized extracellular matrix in the liver. EXPERIMENTAL DESIGN: A cDNA probe encoding a portion of the murine lysyl oxidase was cloned, and antibodies were raised against the corresponding recombinant peptide expressed as a fusion protein. Both tools were used to examine the expression of the lysyl oxidase mRNAs and peptides, all within granulomas and cells extracted from infected liver. RESULTS: Transient up-regulation of two dominant 4.5 kb and 5.5 kb transcripts was observed among four mRNAs hybridizing with the lysyl oxidase cDNA probe during the development of granulomas. An identical time course was obtained for alpha 1(I) procollagen messenger expression. The lysyl oxidase expression was observed in type I collagen producing cells mainly localized at the periphery of fibroinflammatory granulomas and it disappeared in late granulomas. The lysyl oxidase and type I collagen expressing cells, located within granulomas, exhibited the characteristics of myofibroblasts, as judged by their expression of alpha-smooth muscle actin and desmin and by their ultrastructural morphology. Four antigenically related peptides were immunopurified from an enriched preparation of myofibroblast-like cells extracted from infected mouse liver. Two of these peptides had the molecular weight of prolysyl oxidase (50,000) and activated lysyl oxidase (32,000). The two others (28,000 and 66,000) might correspond to cleavage product or dimeric form respectively. CONCLUSIONS: This study demonstrates that the lysyl oxidase was transiently up-regulated at the transcriptional level parallely to alpha(1)I procollagen within developing granulomas. Myofibroblasts are involved in the expression of the lysyl oxidase which may be secreted as a proenzyme and an activated enzyme.

Animals↗