Expression and cellular distribution of glucose transporters and alpha subunits of Na+/K+-ATPase in the heart of fructose-fed female rats: the role of estradiol.

Remarkable parallels are observed between glucose transporters (GLUT) and subunits of Na+/K+-ATPase, which deal with insulin regulation, tissue specificity, intracellular distribution and function of these proteins. To test our hypothesis that similarities also exist in alteration of cardiac GLUTs and alpha subunit isoforms of the pump in insulin resistance, animal model of fructose rich diet was exploited. The role of estradiol in regulation of GLUTs and Na+/K+-ATPase in insulin resistance context was studied as well. Cardiac protein expression, as well as insulin-regulated cellular localization of GLUT4, GLUT1, and α1 and α2 subunits of the pump were analyzed by Western blot. Fructose rich diet increased plasma insulin level and HOMA index, while estradiol treatment reversed both parameters to the control level. We did not observe obvious similarities in the pattern of alterations of GLUT1/α1 subunit of the pump, as well as GLUT4/α2 subunit, related to diet or hormone treatment. Considering alterations in expression and cellular localization of GLUTs and the pump subunits, fructose rich diet jeopardized cardiac glucose transport in some extent, but in contrast, stimulated Na+/K+-ATPase function. Estradiol treatment opposed the fructose diet biochemical action and the effect on cardiac GLUTs, but was inefficient concerning the changes of cardiac Na+/K+-ATPase subunits. Changes of the cardiac molecules can be mediated by alterations in the level of insulin and nonesterified fatty acids, induced by the diet and hormone treatment.

Interaction between insulin and estradiol in regulation of cardiac glucose and free fatty acid transporters.

The estrogen binding to specific extranuclear receptors (ER) activates several intracellular pathways that are activated by insulin as well. Moreover, insulin and estradiol (E2) influence cardiac energy substrates, blood glucose and free fatty acids (FFAs), and both hormones exert cardio-beneficial effects. In view of these facts, we suggest that cross-talk between their signaling pathways might have an important role in regulation of cardiac energy substrate transport. Ovariectomized rats were treated with insulin, estradiol (E2), or their combination 20, 30, or 40 min before analysis of blood glucose and FFA level, as well as cardiac plasma membranes (PM) and low density microsomes (LDM) content of glucose (GLUT4 and GLUT1) and FFA (CD36) transporters. Insulin, given alone, or in combination with E2, decreased plasma glucose level at all time points, but did not influence FFA level, while E2 treatment itself did not change glucose and FFA concentration. Insulin increased PM GLUT4 and GLUT1 content 30 and 40 min after treatment and the increases were partially accompanied by decrease in transporter LDM content. E2 increased PM content and decreased LDM content only of GLUT4 at 30 min. Insulin generally, and E2 at 20 min increased CD36 content in PM fraction. Both hormones decreased CD36 LDM content 20 min after administration. Effect of combined treatment mostly did not differ from single hormone treatment, but occasionally, particularly in distribution of GLUT4, combined treatment emphasized single hormone effect, suggesting that insulin and E2 act synergistically in regulation of energy substrate transporters in cardiac tissue.

Gastrointestinal and liver tumours and public health in Europe.

STATE OF THE ART: Europe comprises only one eighth of the total world population but has around one quarter of the global total of cancer cases--some 3.2 million new patients per year. While the disproportionate cancer burden is readily apparent, the disease patterns in Europe cannot simply be generalized--overall cancer incidence and mortality rates vary at least two-fold between European countries and the differences are often far greater for specific cancers. With 1.7 million deaths each year, cancer currently represents the second most important cause of death in Europe. The range of survival rates is similarly wide. For individual cancers, the variation across Europe is even greater. This reflects a wide range of social and epidemiological factors in different countries: cancer prevention programmes; screening programmes; cancer control plans; individual lifestyles and occupational exposures; the existence and accessibility of health-care facilities and technological infrastructure; and the availability of human, financial and material resources for health and economic development. Europe has some of the richest countries in the world, but also some of the poorest. In 2002, 168 million people were living below the poverty line, about 46% of the European population. The time trends in cancer risk also vary between European countries and some cancers show different trends between men and women, or young and old, or poor and rich. The public health profile of cancer in Europe is complex. Trends in the incidence and mortality rates are also influenced by successes in health promotion (e.g. tobacco control), efficient screening (e.g. breast, bowel, cervix) and better treatment. These have been reflected in lower incidence, reduced mortality, higher survival, improved life expectancy and a better quality of life for cancer survivors. CONCLUSIONS: Cancer of the gastrointestinal (GI) tract is the most common cancer in Europe. More than half of GI cancer cases arise from the colon. They can remain asymptomatic until late in the natural history of the disease, and as this is the stage at which they can be cured, screening has been advocated for well members of the population and surveillance for those with conditions predisposing to cancer.

Insulin signaling in the liver and uterus of ovariectomized rats treated with estradiol.

We used rat hepatic and uterine tissues to examine the impact of estradiol (E2) on insulin (INS) signaling. Ovariectomized (OVX) female Wistar rats were treated with E2 (20 microg/kg b.wt., i.p.) and used for the experiment 6h after E2 administration. To highlight E2 effects on tyrosine phosphorylation of INS receptor (IR) and INS receptor substrates (IRSs) and IRSs association with p85 subunit of phosphatidylinositol 3-kinase (PI3-K) in the context of INS signaling, E2-treated OVX rats were also injected with INS (20 IU, i.p.), 30 min before the experiment. Treatment with E2 did not change the levels of plasma INS and glucose (Glu). However, it significantly decreased the free fatty acid (FFA) level and increased uterine weight. Furthermore, the results show that E2 had no effect on the content of hepatic IR protein, but significantly increased IR protein content in the uterus and decreased IR tyrosine phosphorylation in both the liver and uterus. Compared to the control, hepatic IRS-1 and IRS-2 were significantly decreased and increased, respectively, after E2 treatment. Protein content of both molecules, IRS-1 and IRS-2, was increased in uterine tissue after E2 administration. Protein content of the p85 subunit of PI3-K and that of protein kinase B (Akt) were increased in the uterus, with no changes in the liver. The results suggest that E2 treatment induces tissue-specific changes in INS signaling. The consequences of E2 treatment on INS signaling molecules are more apparent in the uterus, but their physiological relevance for INS action is probably greater in the liver.

[Bleeding oesophageal varices--therapeutic options].

INTRODUCTION: Emergency endoscopy plays the most important role in diagnosis and treatment of patients with esophageal variceal bleeding. Endoscopic sclerotherapy (EST), placement of esophageal band ligatures (EVL), medicamentous treatment using somatostatin and its derivatives and balloon tamponade are the methods most frequently applied in treatment of the bleeding esophageal varices. PATIENTS AND METHODS: Endoscopic reports on the patients with bleeding esophageal and gastric varices were retrospectively analyzed in the emergency unit of the Clinic of Gastroenterology and Hepatology, Clinical Center of Serbia over the five-year period--since January 2001 till December 2005. RESULTS: The total of approximately 3, 954 emergency upper endoscopies were performed due to the upper gastrointestinal tract bleeding. Out of the total number of patients, bleeding was diagnosed in 324 (8.2%) patients due to the esophageal varices. In the group of patients with bleeding esophageal varices, the total of 252 (77.8%) males and 72 (22.2%) females averagely aged 56.8 + 7.5 years (range 24 - 80 years) were examined. The primary sclerosant therapy with absolute alcohol was applied in 118 (36.4%) patients, while Blakemore probe tamponade was performed in 145 (44.8%) patients with bleeding esophageal varices. The total of 240 (74.1%) patientswere treated with vasoactive substances (somatostatin and its analogues), as additional therapy and control of the primary hemostasis. It was evidenced that out of 118 patients intra and paravariceally treated with the sclerosant agent (absolute alcohol) hemostasis was achieved in 47 (39.8%). Out of 145 patients subjected to Blakemore probe placement, bleeding was successfully arrested in 117 (80.7%) patients. Somatostatin and its analogues as primary and only treatment of the bleeding esophageal varices were applied in 71 (29.6%) patients, while in the remaining 169 (70.4%) patients, they were applied as additional therapy to the endoscopic sclerotherapy and mechanical treatment of bleeding. Out of 71 patients treated with somatostatin preparations as the only therapeutic option, 45 (63.4%) responded positively by arrest of bleeding for 72 hours. CONCLUSION: Treatment of the acute bleeding esophageal varices is focused on the arrest of bleeding, prevention of early recurrent bleeding and reduction of mortality. Based on the most recent studies, efficacy of the modern endoscopic therapy in the form of sclerotherapy and band ligature placement, as well as application of vasoactive substances reaches up to 90%. Our results evidence minimal efficacy of the sclerotherapy (approximately 40%), which indicates the need of better preparation of patients for the intervention itself and additional education of the personnel.

[Endoscopic haemostasis of bleeding duodenal ulcer].

INTRODUCTION: Acute upper gastrointestinal bleeding is the commonest emergency managed by gastroenterologists. It manifests like: haematemesis, melaena or haemochezia. Diagnostic endoscopy accurately defining the cause of haemorrhage, while therapeutic endoscopy improves prognosis in patients who present with severe bleeding. Endoscopic therapies can be classified as those based on injection, application of heat, or mechanical clips. PATIENTS AND METHODS: This investigation was conducted in Department of endoscopic haemostasis, Clinic for gastroenterology and hepatology, CCS, using retrospective analysis of patients with acute upper gastrointestinal bleeding during the last five years. The aim of this study was to establish the number of upper gastrointestinal bleeding in our hospital during the last five years, and distribution of income according to type, difficulty, cause factors and risk factors of gastrointestinal bleeding and method of haemostasis. RESULTS: In Department of endoscopic haemostasis 3954 patients with upper gastrointestinal bleeding were endoscoped, and 33.4% of them had bleeding duodenal ulcer. Male patients were statistically significant more present than female patients in group with duodenal ulcer 71.8%: 28.2%). 79.7% patients with duodenal ulcer had only haematemesis, while 14.4% patients had haematemesis and melaena. 59.1% patients with bleeding duodenal ulcer consumed salicylates and/or non-steroidal anti-inflammatory drugs (NSAIDS) (statistical significant differences chi2 test; p = 0.007). Only endoscopic injection was used: in 36.8% of patients used injection of adrenaline solutions, while in 5.9% of patients used injection of adrenaline and absolute alcohol solutions. CONCLUSION: Using of therapeutic endoscopy improves better prognosis in patients who present with severe acute upper gastrointestinal bleeding. Endoscopist's experience is an important independent prognostic factor for acute upper gastrointestinal bleeding.

[The influence of Helicobacter pylori eradication on appearance of gastro-oesophageal reflux disease].

UNLABELLED: Gastro-oesophageal reflux disease (GERD) includes wide spectrum of symptoms caused by gastric acid regurgitation through the incompetent lower oesophageal sphincter in oesophagus. Etiopathogenesis of GERD is multifactorial. AIM OF THIS STUDY: to establish the relationship between Helicobacter pylori eradication and appearance or aggravating of present GERD. If this relationship exist, the aim is to estimate its level and clinical consequences. MATERIAL AND METHODS: 50 Helicobacter pylori positive patients with different endoscopic findings (ulcer disease, gastritis and non-ulcer dyspepsia) to whom eradication of Helicobacter pylori was done, were following next 6 months. Questionnaire, uppear GI endoscopy with verification changes of oesophagus in accordance to LA classification, histopathological examination of gastric and oesophageal mucosal biopsy specimens, and oesophageal manometry have been done to all patients. These examinations have been done before Helicobacter pylori eradication and one, three. six and none months after that. RESULTS: non statistical significant difference was found among the appearance or aggravating of present GERD in all patients during the following period (Cochran Q test; p=0,408). Non statistical significant difference was found among the endoscopic types of oesophagitis (LA classification) in all patients during the following 6 months (Friedman test; p=0,058). Non statistical significant difference was found among the changes of histopathological findings on distal oesophagus, too (Friedman test; p=0,217). CONCLUSION: Eradication od Helicobacter pylori infection does not cause the appearance or aggravating of present GERD. The presence of mildly form of GERD, or aggravating of present GERD is transitory, and haven't the statistical signification.

Detection of gastrointestinal and abdominal infections by 99mTc-ciprofloxacin.

BACKGROUND/AIMS: The aim of the study is detection and evaluation of the abdominal and gastrointestinal infective foci using 99mTc-ciprofloxacin (Laboratory for radioactive isotopes, Vinca). METHODOLOGY: In total 21 patients with clinical suspicion on abdominal or gastrointestinal infection were investigated. In all the patients, planar liver/spleen scintigraphy was performed. Ciprofloxacin chloride (3.5 mg) was mixed with 555 MBq of 99mTc in 3 mL of physiological solution and incubated for 20 min. After slow i.v. injection in a cubital vein, dynamic acquisition (1 f/min) was performed during the first 60 min in the position of interest, followed by static acquisition (500,000 imp) anterior and posterior view, abdomen and pelvis after 1 h and 4 h in all patients. When necessary, additional scintigrams were acquired after 24 h. In all the patients with negative or equivocal findings of planar scintigraphy, emission computerized tomography (SPECT) was performed (60 positions, 6 degrees). Interpretation was made by three independent observers. Additional data were provided using clinical findings, ultrasonography, computed tomography and magnetic resonance imaging, laboratory analyses, and surgical or microbiological confirmation of infection. RESULTS: There were eleven true-positive findings, seven true negative, two were false negative while one was false positive due to intestinal obstruction. Sensitivity was 79%, specificity 91%, positive predictive value 92%, negative predictive value 77%, accuracy 84%. CONCLUSIONS: According to our results, scintigraphy with radiolabeled ciprofloxacin is a useful method for detection and assessment of exact localization of abdominal and gastrointestinal infections.

[Radionuclide detection of Helicobacter pylori infection].

The aim is the assessment of the HP infection in stomach using breath test and comparison to other diagnostic methods, as well as following up the effect of therapy. In 83 patients with digestive discomfort rapid urease test, histology and breath test were performed, while in 25 patients with proven HP infection the effect of therapy was followed up using breath test and clinical findings. For rapid urease test and histology, samples were taken from antral mucosa. Breath test was performed after per oral administration of the capsule of 14C- urea (37 kBq) (Izotop, Hungary and Laboratory for radioactive isotopes, Vinca) which, in the presence of Helicobacter pylori breaks up to 14CO2 and NH3. Radioactivity was measured by beta counter in the exhaled air fasting and 30 minutes after ingestion of the capsule. According to our results, the rise of activity over 100% was considered positive. From 83 patients, 58 were breath test was positive, 24 negative and one equivocal. Fast urease test was in 54 positive, in 29 negative while histology was in 57 postitive and 26 negative. Findings of the breath and urease tests were in accordance in 93% patients while breath test and histology in 98% patients. During follow up of the therapeutic effects, breath test and clinical findings were in accordance in 98% patients. Breath test can be useful in diagnosis but is a method of choice in following up the patients after therapy for H. pylori infection, because it is non-invasive, fast and precise.

Anti-CagA and anti-VacA antibodies in Helicobacter pylori-infected patients with and without peptic ulcer disease in Serbia and Montenegro.

BACKGROUND: The expression of two Helicobacter pylori proteins, CagA and VacA, is associated with more severe pathogenesis and clinical outcomes of the infection. However, this association varies among geographical regions and ethnic groups. We therefore evaluated CagA and VacA seroprevalence in H. pylori-positive dyspeptic patients in Serbia and Montenegro. METHODS: In 173 consecutive dyspeptic patients referred to endoscopy (67M, mean age 49 +/- 15, 76 smokers), immunoblot assay was used to detect serum antibodies against CagA and VacA. Presence of H. pylori infection was assessed using a rapid urease test (RUT), routine histology and serology (anti-IgG ELISA). Duodenal ulcer (DU) was diagnosed in 28, gastric ulcer (GU) in 3 and non-ulcer dyspepsia (NUD) in the remaining 142 patients. RESULTS: 129 (74.6%) patients were H. pylori-positive, 27 (96.4%) with DU, 3 (100%) with GU and 99 (69.7%) with NUD (P < 0.01); 121 (93.8%) patients carried anti-CagA antibodies and there was no difference between the DU and NUD groups. VacA antibodies were detected in sera of 50 (38.75%) and were more prevalent in patients with DU compared to the NUD group (P < 0.05). CONCLUSIONS: In Serbia and Montenegro there is high seroprevalence of CagA-positive H. pylori strains in dyspeptic patients with and without peptic ulcer, while VacA-positive strains are more closely related to peptic ulcer disease.

The effect of O-glcnac glycosylation of rat liver nucleoproteins on their acute phase-dependent binding ability to the hormone responsive element of the haptoglobin gene.

We examined whether the transcriptional activation of the rat haptoglobin (Hp) gene during the acute phase (AP) response reflects the O-linked N-acetylglucosamine (O-GlcNAc) status of liver nucleoproteins (NPs) and their binding for the hormone responsive element (HRE). After deglycosylation with N-acetylglucosaminidase of the O-GlcNAc glycoproteins obtained by WGA, affinity chromatography and South-Western analysis, it was observed that only increased HRE binding ability of p64/p70 in control and p51 obtained from turpentine-treated rats can be directly attributed to the presence of O-GlcNAc residues. Therefore, expression of the rat Hp gene could be controlled by this modification of certain trans-acting NPs.

Expression of the rat liver haptoglobin gene is mediated by isoforms of C/EBPalpha, -beta and -delta proteins.

CCAAT/enhancer binding proteins (C/EBP) alpha, -beta and -delta play an important role in mediating I interleukin-6 (IL-6) dependent expression of acute-phase protein (APP) genes in liver during acute-phase (AP) response. Based on the presence of type IL-6 responsive element (IL-6 RE) in the rat haptoglobin (Hp) gene promoter we assumed that some C/EBPalpha, -beta and/or -delta isoforms could mediate the expression of this gene during turpentine-induced AP response. By Western immunoblot and Northern blot assays, we found that turpentine treatment of rats led to a coordinate induction of C/EBPbeta and -delta as well as repression of C/EBPalpha isoforms pool levels in rat liver nuclear extracts (NEs) which was preceded by an adequate alteration of their mRNAs expression in liver. Consequently, results of DNA affinity chromatography revealed that affinity of certain C/EBPalpha isoforms to bind the type I IL-6 RE within the rat Hp gene promoter decreased whereas affinities of certain C/EBPbeta isoforms and C/EBPdelta were increased and induced, respectively. Our data suggest that turpentine-induced alterations of C/EBPalpha, -beta and -delta pool levels and DNA-binding activities can be regarded as an integral part of activation of the Hp gene expression in the course of AP response.

Radioimmunodetection of colorectal carcinoma.

BACKGROUND/AIMS: The aim of the study is detection of the recurrences and metastases of colorectal carcinomas using 111In-labeled antibodies B72.3. METHODOLOGY: Fourteen patients underwent planar immunoscintigraphy and/or tomoscintigraphy. RESULTS: With tomography in comparison to planar scintigraphy, we can access better distinction of tumor and estimation of its size. Other imaging methods (computed tomography, ultrasonography) have an advantage in detection of liver metastases, while immunoscintigraphy is more specific for the assessment of malignant abdominal tumors and extrahepatic metastases. CONCLUSIONS: The first results point out that Oncoscint CR-103 can be useful in diagnosis of recurrences and metastases of colorectal carcinoma, viability assessment after radiotherapy and in the choice of the adequate surgical treatment in dependence of the spread of the disease.

DNA binding activity of C/EBPbeta and C/EBPdelta for the rat alpha2-macroglobulin gene promoter is regulated in an acute-phase dependent manner.

Turpentine-induced acute-phase (AP) response in rats is followed by transcriptional activation of the alpha2-macroglobulin (MG) gene mediated by cytokine interleukin-6 (IL-6) and glucocorticoids. Based on nucleotide sequence analysis of the alpha2-MG gene promoter regions responsive to IL-6, we postulated that binding of members of the liver-enriched CCAAT-enhancer-binding proteins (C/EBP) family of transcription factors to the type I IL-6 responsive element (IL-6RE) may participate in the transcriptional activation of this gene during AP response. Results of Western immunoblot and Northern-blot assays revealed coordinate changes in the pool levels of C/EBPalpha, -beta. and -delta protein isoforms and their genes expression in liver in response to turpentine. By means of an in vitro phosphorylation assay, South-Western blot, and selective proteolysis we have also found that only abilities of 35-kD C/EBPbeta and 27-kD C/EBPdelta to bind to the alpha2-MG gene promoter were affected by phosphorylation. Based on these data we concluded that transcriptional induction of the rat alpha2-MG gene during AP response correlates with both increased synthesis and phosphorylation-induced binding of 35-kD C/EBPbeta and 27-kD C/EBPdelta.

Changing pattern of cytokeratin 7 and 20 expression from normal epithelium to intestinal metaplasia of the gastric mucosa and gastroesophageal junction.

It is currently unclear whether intestinal metaplasia at the esophagogastric junction and in the distal esophagus represent a continuum of the same underlying disease process, i.e., gastroesophageal reflux, or constitute different entities with a different pathogenesis. Biopsies below the Z line might show specialized epithelium in some patients and the question is whether this is another form of short segment Barrett's esophagus or whether it is related to a generalized atrophic process of the stomach. Data from recent studies regarding the expression of cytokeratin CK7 and CK20 in intestinal metaplasia (IM) found at the gastroesophageal junction are conflicting. Prompted by these data we undertook the present study: a) to evaluate the expression of CK7 and CK20 in IM of the gastric cardia and to compare the findings with those in patients with Barrett's esophagus and IM of the gastric corpus and antrum mucosa; and b) to evaluate the immunophenotype of non-intestinalized cardiac mucosa and to compare it with that of normal gastric epithelium. We studied the expression of CK7 and CK20 on biopsy specimens from patients with long-segment Barrett's esophagus (n=17) and surgical resection and biopsy specimens of gastric cardia (n=15), corpus (n=14) and antrum (n=22) from patients with histological evidence of IM. Eighty-four biopsy specimens from 42 patients (antrum n=15, corpus n=20, cardia n=7) without evidence of IM were studied as a control group. We observed an immunophenotype characterised by diffuse moderate to strong CK7 staining on the surface and crypt epithelium combined with strong CK20 staining on the surface and superficial part of the crypts in 94.1% (16/17) of the cases with long-segment Barrett's esophagus, but in none of the 36 cases with IM in distal stomach (antrum and corpus). IM in the gastric cardia expressed the immunophenotype seen in IM of the gastric mucosa in 93.3% (14/15) of the cases. On the other hand, normal cardiac epithelium expressed patchy strong CK7 staining on the surface epithelium and on both, superficial and deep parts of the pits combined with patchy strong CK20 staining on the surface epithelium and superficial pits, a feature permitting distinction of the normal cardiac epithelium from those of the normal gastric antrum and corpus epithelium. We conclude that the expression of cytokeratins 7 and 20 can be used to distinguish the origin of IM of the gastroesophageal junction. The CK7/20 immunophenotype of IM in the gastric cardia closely resembles that of the IM in the gastric antrum and corpus and is different from IM in long-segment Barrett's esophagus. In contrast, the CK7/20 immunophenotype of the cardiac epithelium is different from that of the gastric antrum and corpus mucosa, suggesting that cardiac epithelium might not be a native normal gastric epithelium but one that is acquired as a consequence of longstanding inflammation. Changing pattern of CK7 and CK20 expression from normal to intestinalized epithelium suggests that IM arising from cardiac epithelium might have distinctive features.

[The Mirizzi syndrome--from the first description until today]. / Mirizzi-ev sindrom--od prvog opisa do danas.

Pablo Luis Mirizzi was the first to describe an obstructive jaundice caused by compression of the common hepatic duct by the stone in the cystic duct or the neck of the gallbladder in 1948. McSherry et al in 1982. described a new type of Mirizzi's syndrome calling it type II. Csendes et al in 1989. gave a new classification in four types. According to it, type II of Mirizzi's syndrome was devided in three types depending on the size of the destruction of the common hepatic duct. We previously described a subtype of Mirizzi's syndrome in which besides very wide cholecystohepatic fistula, a combined fistula with duodenum was developed. Nagakawa et al in 1997. described a new type of Mirizzi's syndrom and gave their classification of syndrome in four types. In the present article the authors proposed a combined classification which takes into account not only all described variant of the syndrome but possibilities of operative reconstruction. Type I would be the same as in all previous classifications. Type II would correspond to the cholecystohepatic fistula in which a primary repair is possible. Type III would correspond to the cholecystohepatic fistula in which a primary repair is not possible so that biliodigestive anastomosis has to be carried out. Subtype IIIa would correspond to the same situations but complicated with fistula with the duodenum which has to be repaired as well. A Type IV of Mirizzi's syndrome would correspond to the inflammatory obstruction of the common hepatic duct as described by Nagakawa et al.

Opposite nuclear level and binding activity of STAT5B and STAT3 proteins with rat haptoglobin gene under normal and turpentine induced acute phase conditions.

Transcription of the rat gene encoding haptoglobin (Hp) is highly induced during acute phase (AP) response which has been previously shown to be mediated by inducible STAT3 member of the Signal Transducer and Activators of Transcription (STATs) family proteins. In this study, we observed that under normal but not in the turpentine induced AP conditions, another member of the STAT family proteins, STAT5b is expressed and binds to the hormone regulatory element (HRE) of the rat Hp gene. We found that the nuclear amounts of constitutively active STAT5b in rat liver decreased significantly with time of turpentine treatment as opposed to that of cytosol STAT5b, suggesting possible export of constitutive STAT5b from the nucleus. Nuclear accumulation and binding of inducible STAT3 proteins to the rat Hp gene HRE following turpentine treatment implicated that STAT5b negatively regulates Hp gene expression during normal conditions.

HMG-1 as regulatory trans-acting protein in the acute phase-induced expression of the rat liver haptoglobin gene.

Expression of the haptoglobin (Hp) gene is liver specific and acute phase (AP) responsive. It was previously shown that transcriptional induction process of the rat Hp gene during turpentine induced AP response has been mediated by the liver nucleoprotein p29 which was shown to be homologous to the HMG-1 chromatin-associated protein. The results presented in this report offered further evidence for the existence of structural and functional similarities between these two proteins implicating an involvement of HMG-1 in the regulation of the rat Hp gene transcription. By DNA binding assays we found the HMG-1 binding sites in the rat Hp gene cis-regulatory subelements A and C and revealed an increase in its DNA-binding after induction of AP response. In view of our previous and here shown data we assume that this increase could be a consequence of AP-induced release of HMG-1 from the chromatin and subsequent increase in its nuclear amount.

STAT3 involvement in the acute phase-related expression of the rat haptoglobin gene.

Turpentine-induced acute-phase (AP) response in rats is followed by transcriptional activation of the haptoglobin (Hp) gene in liver. Analysing the promoter sequence of the rat Hp gene we postulated an involvement of Signal Transducer and Activator of Transcription 3 (STAT3) in the regulation of this process. Results obtained by using a combination of Western immunoblot and DNA-binding assays revealed AP-induced binding of constitutive 86kD-and inducible 91kD-STAT3 isoforms to the rat Hp gene inducible promoter element. On the basis of these data we assumed that AP-related interactions of these two STAT3 isoforms correlates with an activated transcriptional status of the rat Hp gene.