Biomedical subjects
G Ramadori
Publications and source records attributed to G Ramadori.
Mononuclear phagocytes of acutely injured rat liver abundantly synthesize and secrete fibronectin in contrast to Kupffer cells of normal liver.
Fibronectin (FN) is a multifunctional glycoprotein involved in wound healing. It is early deposited after liver injury in necrotic areas. The cellular source of this FN remained undetermined. For this reason, mononuclear phagocytes (MNP) of normal and acutely CCl4-injured rat liver were isolated, characterized immunocytochemically and kept in culture. Synthesis of FN was studied by biosynthetic labelling, immunoprecipitation, and SDS-PAGE and on RNA level by Northern blotting and hybridization with 32-P-labeled, FN-specific cDNAs. In contrast to normal liver, MNP of acutely injured livers synthesized and secreted FN in abundant amounts. Synthesis was higher in small than in large MNP and higher in MNP isolated 36 h after the injury (vs 60 h) and decreased during the time in culture. MNP could be an important cellular source of FN deposited in the early stage of liver injury.
Viable rat Kupffer cells synthesize but do not secrete interleukin-1: indications for necrosis-induced maturation of interleukin-1 alpha, but not of interleukin-1 beta.
Interleukin-1 is involved in host defense to infection and injury. In this work synthesis and secretion of IL-1 by cultured rat liver macrophages (Kupffer cells) in response to lipopolysaccharide were investigated. IL-1 was found only intracellularly as 31-kD (pro-IL-1 alpha) and 34-kD (pro-IL-1 beta) proteins. No mature 17-kD IL-1 alpha or IL-1 beta was detected in cell lysates or supernatants. Pulse-chase experiments showed that there was no release of IL-1 even after 24h, although pro-IL-1 continuously disappeared from the cells. Cultures were lysed by freezing-thawing. Pro-IL-1 beta was then found in the supernatants, but pro-IL-1 alpha was processed into several smaller fragments. A 17-kD protein could represent the mature IL-1 alpha. The results indicate that Kupffer cells are not able to secrete biologically active mature IL-1 proteins. By lysis of the cells. IL-1 is released. Pro-IL-1 alpha is processed, but pro-IL-1 beta seems to need further activation processes.
Possible association between Behçet's syndrome and chronic hepatitis C virus infection.
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Accumulation and cellular localization of fibrinogen/fibrin during short-term and long-term rat liver injury.
BACKGROUND/AIMS: During liver fibrosis, there is a putative pacemaker role of fibronectin. Fibrinogen is closely linked to fibronectin during clotting processes. The aim of this study was to show fibrinogen gene expression during liver damage. METHODS: Fibrinogen/fibrin deposition in damaged livers was studied by immunohistology. Fibrinogen gene expression was analyzed in vivo in a model of CCl4-induced rat liver damage and in vitro in isolated liver cells by means of Northern blot analysis and in situ hybridization. RESULTS: Immunohistology showed striking amounts of fibrinogen and fibrin deposits in pericentral necrotic areas (short-term damage) and within fibrotic septa (long-term damage). Total RNA extracted from short-term-damaged livers contained an increased fibrinogen messenger RNA level. By in situ hybridization, fibrinogen transcripts were localized in cells of the nonnecrotic areas (short-term damage) and outside fibrotic septa (long-term damage). In vitro studies showed fibrinogen de novo synthesis restricted to hepatocytes. CONCLUSIONS: The results show fibrinogen/fibrin deposition during short-term liver injury and liver fibrogenesis, which may suggest the involvement of a "clotting-like process" in short-term liver damage and liver fibrosis. The data might indicate that fibrin/fibronectin constitute a "provisional matrix," which affects the attraction and proliferation of inflammatory and matrix-producing cells.
Glucose metabolism and liver cirrhosis.
Chronic liver disease is characterized by numerous metabolic alterations, predominantly catabolic, resulting in the clinical picture of malnutrition and even cachexia in some patients. The following review focuses on disturbances of glucose metabolism and of hormonal interactions that could contribute to the clinical picture of malnutrition seen in chronic liver disease. Body composition is altered in a characteristic manner with an increase in fat mass and a significant loss of muscle tissue. Furthermore, defective glucose storage due to reduced insulin sensitivity predominantly of muscle tissue has been observed. The pathogenesis of insulin resistance leading to an impaired glucose tolerance or a manifest diabetes mellitus is as yet unknown. A receptor/postreceptor dysfunction probably exists in chronic liver disease that might be explained by the following factors: 1. Altered membrane lipid composition and increased levels of free fatty acids; 2. long-lasting hyperinsulinemia; 3. increased plasma levels of insulin counteracting hormones such as growth hormone, glucagon, catecholamines and possibly cytokines; 4. a lack of liver-derived humoral factors with insulin-like activity, i.e. insulin-like growth factors I and II.
Expression of von Willebrand factor in normal and diseased rat livers and in cultivated liver cells.
Von Willebrand factor (vWf) is an adhesive glycoprotein known to play an important role in hemostasis and in tissue injury. Because the latter process resembles hepatic fibrogenesis, we studied the tissue distribution of vWf in diseased livers. In normal rat liver vWf was strongly expressed in the vascular endothelium and as small spots or fiber-like structures in the hepatic parenchyma. During acute liver injury, pronounced staining was observed within the area of necrosis. In fibrotic livers vWf deposits were distributed predominantly at the scar-parenchyma interface but also within the septum and in sinusoidal lining cells. Testing different liver cell populations in vitro demonstrated that vWf gene expression was limited to endothelial cells (ECs) and, therefore, the latter cell population might represent the vWf-positive cells detected in vivo. The distribution of vWf within fibrotic septa suggests that vWf becomes a component of the extracellular matrix (ECM) in fibrotic livers.
Treatment of metastasized midgut carcinoids with dacarbazine.
Seven patients with metastasized midgut carcinoids were treated with intravenous infusion of dacarbazine [dimethyltriazenoimidazole carboxamide (DTIC)] (650 mg/m2) every 4 wk. After 2 wk, white blood cell counts decreased transiently in three patients. No other DTIC-associated side effects occurred. Biochemical markers of disease activity decreased significantly in four patients for 4-20 months (mean duration, 12 months). Size of hepatic metastases was reduced or remained unchanged in six patients for 6-20 months (mean duration, 10 months). Clinical symptoms such as cutaneous flush, diarrhea, abdominal pain, constipation, night sweat, or weight loss improved in six of seven patients. We conclude that DTIC represents a useful therapeutic option in the treatment of advanced and metastasized carcinoid tumors.
[Cholestatic pruritus--pathophysiology and therapy with special reference to treatment with 5-hydroxytryptamine subtype 3 receptor antagonists].
Our current knowledge about the pathophysiology of pruritus (itch) is summarized. Special concern is given to the hypotheses to explain itch due to cholestatic liver diseases (bile acids, generation of hepatic and intestinal pruritogens, endogenous opioids). Drugs used for the treatment of cholestatic itch are discussed in detail. On the basis of successful treatment of cholestatic itch with 5-hydroxytryptamine (serotonin) subtype-3 receptor antagonists the role of serotonin in nociception is discussed.
Expression of the complement C8 genes during interleukin-6-mediated in vitro induction of the acute-phase response.
The three chains of the human complement component C8-alpha, beta and gamma- are encoded by distinct structural genes. C8A and C8B are closely linked on chromosome 1p and C8G is located on chromosome 9q. The biosynthesis and regulation of the gene products were studied in the human hepatoma-derived cell line HepG2 after in vitro induction of the acute-phase response by incubation with the cytokine interleukin IL-6. Analysis of C8 expression by immunoprecipitation and SDS-PAGE of biosynthetically labeled alpha-gamma and beta subunits demonstrated a positive response to this cytokine. The expression pattern observed in the hepatoma cells characterizes C8 in vitro as a positive acute-phase protein. In addition, the comparison of the relative amounts of the C8 transcripts provides evidence for a post transcriptional regulation of the C8 beta subunit. No evidence was obtained for an increased expression of IL-6 or IL-6 receptor mRNA thus excluding autoregulatory mechanisms of the cytokine in HepG2 cells.
Treatment of diarrhea in carcinoid syndrome with ondansetron, tropisetron, and clonidine.
A 69-yr-old man with known carcinoid syndrome treated with octreotide and interferon-alpha 2b developed diarrhea, with six to eight watery to semiliquid stools per day. Diminished stool frequency and increased stool consistency were obtained by treatment with the 5-hydroxytryptamine-3 receptor antagonists ondansetron and tropisetron. Successful alleviation of the diarrhea was also observed with the alpha 2-receptor agonist clonidine. These observations indicate that these classes of drugs should be evaluated in a controlled trial in patients with carcinoid-associated diarrhea.
[Chronic hepatitis C: a growing problem].
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Syndecan-1 gene expression in isolated rat liver cells (hepatocytes, Kupffer cells, endothelial and Ito cells).
Normal liver contains mainly heparan sulfate proteoglycans. To determine which liver cells are able to express syndecan-1 RNA, hepatocytes, endothelial, Kupffer and Ito cells were isolated from normal rat liver and kept in culture. Rat fibroblasts, monocytes and peritoneal macrophages were also studied. Immediately after isolation the steady state level of syndecan messages in hepatocytes was comparable to that of the normal liver. The expression increased at day one and then remained constant until day five. Ito and endothelial cells contained a low amount of syndecan message. Freshly isolated Kupffer cells failed to express syndecan, but strong upregulation was found on the first day in culture which gradually decreased by day 5. Syndecan transcripts were dose and time dependently upregulated by endotoxin and gamma interferon in Kupffer cells. Endotoxin had no effect on fibroblasts.
On the influence of CCK receptor blockade on GRP-mediated pancreatic secretion.
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Human hepatoma cells synthesize and secrete lysozyme: modulation by cytokines.
Plasma lysozyme levels are elevated in several different pathological conditions. In our study we show that well differentiated human hepatoma cells Hep3B and HepG2 are active synthesis sites of lysozyme and that this synthesis can be modulated by acute phase mediators. The production and modulation of lysozyme synthesis was studied by means of Northern-blot analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a specific bioassay after treatment of the cells with interleukin-1 beta, interleukin-6 and tumor necrosis factor-alpha. Hep3B and HepG2 cells constitutively synthesize high amounts of lysozyme. Lysozyme synthesis and secretion were found to be augmented by interleukin-1 beta and tumor necrosis factor-alpha in both cell lines. Interleukin-6 caused an increase in lysozyme production in Hep3B but a decrease in the HepG2 cells. As expected, the synthesis of albumin was decreased in both cell lines. Furthermore we demonstrated that HepG2 and Hep3B cells produce a biologically active form of the enzyme as measured by a specific bioassay. The results demonstrate that lysozyme is constitutively synthesized by Hep3B and HepG2 hepatoma cell lines and that lysozyme synthesis is modulated by acute-phase mediators. Well differentiated human hepatoma cells may respond differently to different cytokines.
Characterization of histamine H3 receptors inhibiting 5-HT release from porcine enterochromaffin cells: further evidence for H3 receptor heterogeneity.
The nature of the histamine receptor mediating inhibition of 5-HT release was investigated in strips of the porcine small intestine by investigating the effects of histamine ligands on the overflow of endogenous 5-HT and its metabolite 5-hydroxyindoleacetic acid (5-HIAA). The overflow was measured by HPLC, combined with electrochemical detection and represents calcium-sensitive 5-HT release from enterochromaffin cells, as reported previously. The histamine H3 receptor selective agonists (R)-alpha-methyl-histamine and imetit inhibited the overflow of 5-HT maximally by 50-60%, with EC50 values of 48 and 3.2 nmol/l, respectively. Effects on 5-HT overflow were always accompanied by similar effects on the overflow of 5-HIAA. Thioperamide (100 nmol/l) shifted the concentration response curve of (R)-alpha-methyl-histamine to the right (pKB value 8.38). The inhibitory effect of 1 mumol/l (R)-alpha-methyl-histamine was antagonized in a concentration-dependent manner by thioperamide (IC50: 65 nmol/l) and dimaprit (IC50: 8.6 mumol/l); however, the effect of (R)-alpha-methyl-histamine was weakly antagonized by burimamide (by 38% at 100 mumol/l) and not significantly affected by other H3 receptor antagonists, such as impromidine, betahistine and phenyl-butanoyl-histamine (each up to 100 mumol/l). In conclusion, H3 receptors mediating inhibition of 5-HT release from porcine enterochromaffin cells have a particular pharmacological profile indicating that heterogeneity of H3 receptors may exist. The data suggest that histamine H3 receptors modulating 5-HT release in pig small intestine do not belong to either H3A or H3B receptors as defined in rat tissue.
Treatment of acute gouty arthritis with the 5-hydroxytryptamine antagonist ondansetron.
We report on a 28-year-old man with hematemesis, renal dysfunction, and arterial hypertension who suffered from an acute gouty attack presenting as podagra. Because of the accompanying symptoms conventional treatment of the gouty attack with colchicine or nonsteroidal anti-inflammatory drugs was contraindicated. We treated the pain of acute arthritis with the specific 5-hydroxytryptamine subtype 3 receptor antagonist ondansetron. Within 30 min after intravenous injection of this drug a substantial degree of pain relief had occurred. Unwanted side effects due to treatment were not observed. It is suggested that the 5-hydroxytryptamine released during a gouty attack induces pain via activation of 5-hydroxytryptamine subtype 3 receptors on nociceptive afferent nerve fibers. 5-Hydroxytryptamine subtype 3 receptor antagonists may therefore be a novel class of drugs for the effective treatment of acute gouty attacks when conventional treatment is contraindicated.
Interferon-alpha 2a increases serum concentration of hyaluronic acid and type III procollagen aminoterminal propeptide in patients with chronic hepatitis B virus infection.
Interferon-alpha (IFN-alpha) has become an important drug for the treatment of chronic viral liver diseases. However, the action of IFN-alpha remains unclear. We investigated whether human recombinant IFN-alpha modulates serum concentrations of hyaluronic acid (HA) and type III procollagen aminoterminal propeptide (P-III-NP) in 56 patients with chronic hepatitis-B under IFN-alpha therapy. IFN-alpha increased the HA serum level in 44 of 46 patients and, after cessation of treatment, HA serum levels returned to the pretherapy levels. The increase of HA serum level was higher in patients with active cirrhosis (aC) than in patients with chronic persistent hepatitis (CPH) and in patients with severe inflammation compared to those with moderate inflammation. Interestingly, HA serum concentration was unrelated to IFN dose and was of no predictive value for therapy response. In contrast, IFN-alpha increased significantly the P-III-NP serum level in patients with aC only. During follow-up, P-III-NP serum level decreased late in responders in parallel to the decrease of serum level of liver enzymes, in non-responders it was without significant change. The first dose of IFN induced a significant increase in HA serum level in each of 10 patients but in none of four healthy volunteers. In contrast, P-III-NP serum concentrations were not influenced by the first IFN-alpha dose. We conclude that: (1) immunstimulation with IFN-alpha induces a rapid increase of HA serum level in patients with chronic hepatitis B but not in normal persons; (2) IFN-alpha increases P-III-NP serum level only in patients with active liver cirrhosis; (3) measurement of HA and P-III-NP serum levels does not help predict response to IFN-alpha, and (4) HA serum level may be used as a compliance indicator.