Nitric oxide synthase mRNA levels correlate with gene expression of angiotensin II type-1 but not type-2 receptors, renin or angiotensin converting enzyme in selected brain areas

Recent data suggest that there is interaction between peripheral angiotensin II and nitric oxide. However, sparse information is available on the mutual interaction of these two compounds in the brain. The potential intercourse of nitric oxide with brain neuropeptides needs to be substantiated by assessing its local production and gene expression of the synthesizing enzymes involved. The aim of the present study was to evaluate whether the gene expression of brain nitric oxide synthase (bNOS) is related to the sites of gene expression of different components of the rat brain renin angiotensin system (renin, angiotensin converting enzyme (ACE) or angiotensin receptors of AT1 and AT2 subtypes). The levels of corresponding mRNAs were measured and correlated in nine structures of adult rat brain (hippocampus, amygdala, septum, thalamus, hypothalamus, cortex, pons, medulla and cerebellum). As was expected, positive correlation was observed between renin and angiotensin-converting enzyme mRNAs. Moreover, a significant correlation was found between brain NO synthase and AT1 receptor mRNAs, but not with mRNA of the AT2 receptor, ACE and renin. Parallel distribution of mRNAs coding for bNOS and AT1 receptors in several rat brain structures suggests a possible interaction between brain angiotensin 11 and nitric oxide, which remains to be definitely demonstrated by other approaches.

Identification of P-selectin glycoprotein ligand-1 as a useful marker in acute myeloid leukaemias

Immunophenotyping is considered to be less valuable in the diagnosis of acute myeloid leukaemias (AML) compared with acute lymphoid leukaemias. Here, we present data on the use of quantitative flow cytometry (QFC) of P-selectin glycoprotein ligand 1 (PSGL-1, CD162) and three-colour immunophenotyping including CD162 staining in the identification of myeloid precursors in AML. Analysis of normal peripheral blood (n = 20) and normal bone marrow (n = 5) samples and on 20 samples from de novo M1, M2, M4 and M5 AML patients demonstrated that PSGL-1 is differentially expressed on various mature and immature leucocyte subsets. It was found by QFC that neutrophils expressed 26500 +/- 4500 and monocytes 47200 +/- 9900 copies of PSGL-1 on their surface, whereas AML blasts from M1 and M2 AML patients expressed significantly less PSGL-1 (12 000 +/- 5300) than mature neutrophils (P < 0.001). In M4 and M5 leukaemias, however, the amount of PSGL-1 on monocytic precursors is displayed in a fairly broad range that is not significantly different from that of mature monocytes (P = 0.084). Using three-colour immunophenotyping PSGL-1-dim staining was co-expressed with CD7 and C34 positivity and PSGL-1 staining intensity on immature myeloid cells paralleled with CD45 expression. This would imply a differential expression of PSGL-1 during myeloid haematopoietic development and suggests that quantification of surface PSGL-1 may aid in differentiating myeloblasts from monoblasts by immunophenotyping in different AML subsets.

Lesion of central part of the dorsomedial nucleus alters vasopressin but not corticotropin releasing hormone mRNA levels in rat hypothalamic paraventricular nucleus

Functional significance of neural projections from the hypothalamic dorsomedial nucleus (DMN) to the paraventricular nucleus (PVN) was investigated using surgical lesion of the central part of the DMN. Under basal conditions, DMN lesion resulted in a decrease in magnocellular vasopressin (AVP) mRNA levels in the PVN, rise in pituitary proopiomelancortin (POMC) mRNA concentrations and elevated plasma corticosterone levels. Corticotropin-releasing hormone (CRH) mRNA levels remained unaffected. In sham operated animals, osmotic stress induced by hypertonic saline injection failed to modify AVP mRNA, but increased CRH and POMC mRNA levels and peripheral hormone release. The rise in CRH mRNA levels after osmotic stress was potentiated in DMN lesioned animals. Thus, the DMN participates in the control of hypothalamic peptide gene expression and pituitary adrenocorticotropic function.

Gene expression of catecholamine synthesizing enzymes in A5 cell group and modulation of tyrosine hydroxylase mRNA by immobilization stress

OBJECTIVE

The A5 group of noradrenergic neurons plays a key role in autonomic mechanisms like cardiovascular regulation, nociception and respiration. The aim of this work was to detect the gene expression of catecholamine synthesizing enzymes in A5 brain nuclei.

METHODS

The gene expression of. tyrosine hydroxylase (TH), dopamine-beta-hydroxylase (DBH) and phenylethanolamine N-methyl-transferase (PNMT) in A5 brain nuclei was estimated. We also investigated various time intervals after the end of the single two-hour immobilization, as well as the effect of short-term repeated immobilization (120 min daily for 7 days) on tyrosine hydroxylase gene expression, the rate-limiting enzymes in catecholamines biosynthesis, in the A5 cell group. For all experiments, reverse transcription with subsequent polymerase chain reaction (RT-PCR) was used.

RESULTS

As expected, we detected a clear signal for TH and DBH mRNA but no signal for PNMT mRNA. Both, single and repeated immobilization stress exposure increased significantly the gene expression of TH in A5 area. Maximal elevation in TH mRNA levels occurred after single immobilization for two hours and subsequent decapitation 24 hours later.

CONCLUSIONS

In this study we detected for the first time the presence of DBH mRNA in micro dissected A5 cell group. We also showed how the gene expression of tyrosine hydroxylase changed with the function of time after the single immobilization exposure. Thus, TH mRNA in A5 cell group is modulated by immobilization stress in a time-dependent manner.

Importance of mental health assessment in HIV-infected outpatients

HIV infection, even when well controlled, may be associated with important mental health problems. We sought to investigate anxiety, depression, and health-related quality of life using screening measurements in patients with HIV infection and to examine their dependency on biosocial parameters relating to HIV. Prospective clinical, virologic, and immunologic data were obtained in a cross-sectional study within the Swiss HIV Cohort Study. Four self-reported questionnaires were used in 397 HIV-infected individuals. The scores for anxiety and depression were high as measured by the Hospital Anxiety and Depression Scale (HADS) and the State Trait Anxiety Inventory (STAI). Half the population scored <75 on a visual analog scale (VAS) Patients were also affected in their quality of life as measured by the HIV Medical Outcome Study (HIV-MOS). Almost all scores were significantly worse for intravenous drug users compared with other transmission groups. People who were employed, with a higher education or with higher CD4 count tended to score better, whereas those who had been hospitalized within the last 6 months, infected for a longer time, with higher viral load, or loss of weight scored significantly worse. A multivariate analysis showed higher education, being employed, low viral load, female gender, and shorter HIV disease duration to be associated with better scores. This study highlights the importance of mental health assessment regardless of HIV-disease parameters.

Hepatic regeneration induces transient acute phase reaction: systemic elevation of acute phase reactants and soluble cytokine receptors

The growth factors present during liver regeneration partially overlap with the regulators of the hepatic acute phase response. We analysed the acute phase reaction and changes in soluble cytokine receptors after partial hepatectomy, when tissue injury inducing acute phase reaction and major reduction of liver mass occur simultaneously. Three acute phase proteins and mRNAs were determined by ELISA and northern blot hybridisation in rats. Serum levels of IL-6 and three soluble cytokine receptors (sTNF-alpha R I and II, sIL-6R) were detected by ELIBA or dot-blot assay. Time-course profiles of fibrinogen, alpha(2)-macroglobulin and haptoglobin proteins and mRNA are presented. Elevation of IL-6, soluble TNF-alpha receptors and soluble IL-6 receptor levels were also detected. The time-course of changes in haptoglobin concentration and elevation of soluble cytokine receptors is described by this in vivo experimental system. The results show good correlation with (post)transcriptional activation of immediate and delayed early gene products. These data suggest the involvement of both acute phase proteins and soluble cytokine receptors in the regulation of liver regeneration.

Reduction of wild type p53 function confers a hormone resistant phenotype on LNCaP prostate cancer cells

BACKGROUND

The protein encoded by the p53 gene is required for some forms of apoptosis and loss or mutations in this gene are found with increased frequency in advanced and hormone resistant human prostate cancers. In order to better appreciate whether reduction of wildtype p53 function in prostate cancer cells might contribute to the development of therapeutic-resistance by these cells, we created stable variants of the androgen-responsive, wild type p53-expressing human prostate cancer cell line, LNCaP, by transfection with expression vectors designed to reduce expression or function of wildtype p53 in them. These cells were then tested for their ability to form tumors in castrated male nude mice.

METHODS

A conditional eukaryotic expression vector (under tetracycline regulation) expressing antisense p53 cDNA was constructed and either directly transfected into LNCaP cells or tranduced into these cells using recombinant retroviruses containing the vector. Stably transfected/transduced cells (LNCaP/Asp53) were evaluated by Western blot analysis for the ability of doxycycline to reduce p53 protein expression and for their ability to form tumors in castrated male nude mice treated or untreated with doxycycline. Additionally, we derived an LNCaP subline (LNCaP/DD) stably expressing a dominant-negative form of p53 and tested these cells for their ability to form tumors in castrated male nude mice.

RESULTS

LNCaP/Asp53 cells showed reduced expression of p53 protein when cultured in a medium containing doxycycline and tested sublines were able to efficiently form tumors in castrated male nude mice only when the mice were treated with doxycycline. LNCaP/DD cells were readily able to form tumors in castrated male nude mice whereas parental LNCaP cells or control-transfected LNCaP cells were not.

CONCLUSION

Loss of wildtype p53 function can contribute to the phenotype of hormone resistance of prostate cancer cells.

Cardiovascular indices of peripheral and central sympathetic activation

OBJECTIVE

A number of sympathetic nervous system (SNS) parameters have been used in cardiovascular psychophysiology. This study aimed to describe the pattern and redundancy of a set of SNS parameters during peripherally induced changes of cardiac sympathetic activation and reflex modulation of central SNS control. Preejection period (PEP) was assessed as a marker of peripheral sympathetic activation. Low-frequency blood pressure variability (BPV) was assessed as an estimate of central SNS control.

METHODS

Peripheral beta-sympathetic stimulation and blockade were achieved with epinephrine and esmolol hydrochloride (beta1-blockade), respectively. Changes in central SNS output were induced by loading and unloading arterial baroreceptors with norepinephrine and nitroprusside sodium, respectively. This single-blinded, crossover study in 24 healthy men also included two placebo control periods. PEP was derived from impedance cardiography and adjusted individually for heart rate. BPV was calculated by power spectral analyses of beat-to-beat heart rate and systolic blood pressure (Finapres system) data.

RESULTS

PEP decreased during epinephrine infusion (-40.1 +/- 3.8 ms, p <.0001) and increased during esmolol infusion (+6.6 +/- 3.5 ms, p =.05). PEP was shortened after central SNS activation by nitroprusside (-16.8 +/- 2.9 ms, p < 0.0001). Systolic BPV in the low-frequency range (0.07-0.14 Hz, Mayer waves) increased during nitroprusside infusion (+0.44 +/- 0.19 ln mm Hg(2), p =.03) and decreased during norepinephrine infusion (-0.67 +/- 0.13 ln mm Hg(2), p < 0.0001). Low-frequency BPV did not change significantly during epinephrine or esmolol infusion.

CONCLUSIONS

Our data provide empirical evidence of separable peripheral and central sympathetic response components. The combined report of low-frequency BPV and PEP gives distinct information on both central SNS control and the level of sympathetic cardiac activation achieved.

Immunohistochemical analysis of atypical ductular reaction in the human liver, with special emphasis on the presence of growth factors and their receptors

AIMS/BACKGROUND

The objective of this study was to characterize the expression of transforming growth factor-alpha/epidermal growth factor receptor, hepatocyte growth factor/c-met, transforming growth factor-beta/Type I-II transforming growth factor-beta receptors, stem cell factor, urokinase plasminogen activator, smooth muscle actin, CD34 and alpha-fetoprotein in human liver samples with (sub)massive necrosis of different etiology containing atypical ductular reaction.

METHODS

Their presence was studied by immunohistochemistry on paraffin-embedded tissue sections.

RESULTS

Transforming growth factor-alpha and -beta, hepatocyte growth factor and their receptors were demonstrated in the ductules; additionally stem cell factor and urokinase plasminogen activator were also expressed. The atypical ductules were surrounded by smooth muscle actin-positive activated stellate cells.

CONCLUSION

These phenotypic similarities confirm that the atypical ductules in the human liver may be equivalent of oval cells in the rat liver, which are regarded as the progeny of stem cells. That is, the atypical ductular proliferation may correspond to a stem cell-fed regenerative process.

Role of DNA minor groove interactions in substrate recognition by the M.SinI and M.EcoRII DNA (cytosine-5) methyltransferases

The SinI and EcoRII DNA methyltransferases recognize sequences (GG(A)/(T)CC and CC(A)/(T)GG, respectively), which are characterized by an (A)/(T) ambiguity. Recognition of the A.T and T.A base pair was studied by in vitro methyltransferase assays using oligonucleotide substrates containing a hypoxanthine.C base pair in the central position of the recognition sequence. Both enzymes methylated the substituted oligonucleotide with an efficiency that was comparable to methylation of the canonical substrate. These observations indicate that M.SinI and M.EcoRII discriminate between their canonical recognition site and the site containing a G.C or a C.G base pair in the center of the recognition sequence (GG(G)/(C)CC and CC(G)/(C)GG, respectively) by interaction(s) in the DNA minor groove. M.SinI mutants displaying a decreased capacity to discriminate between the GG(A)/(T)CC and GG(G)/(C)CC sequences were isolated by random mutagenesis and selection for the relaxed specificity phenotype. These mutations led to amino acid substitutions outside the variable region, previously thought to be the sole determinant of sequence specificity. These observations indicate that (A)/(T) versus (G)/(C) discrimination is mediated by interactions between the large domain of the methyltransferase and the minor groove surface of the DNA.

Changes in angiotensin AT1 receptor mRNA levels in the rat brain after immobilization stress and inhibition of central nitric oxide synthase

OBJECTIVE

To study functional interactions between angiotensin II AT1 receptors and nitric oxide (NO) activity in different brain areas in rats exposed to immobilization stress.

METHODS

Central inhibition of nitric oxide synthase (NOS) was provided by intracerebroventricular (i.c.v.) administration of (N-omega-nitro-L-arginine-methylester) L-NAME and analysis of AT1 receptor mRNA was performed using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) technique. The immobilization in prone position lasted 2 hrs and the rats were sacrificed 24 hr later. The hypothalamus, hippocampus, thalamus, and cortex were isolated from fresh brains.

RESULTS

In the cortex, gene expression of AT1 receptors was unaffected either by L-NAME treatment, or by a single exposure to immobilization stress for 2 hours followed by 24 hours of rest. In the hippocampus, the repeated treatment with L-NAME increased mRNA levels of AT1 receptors approximately 9-times compared to those in the control (untreated) group. Immobilization also increased AT1 receptor mRNA levels in the hippocampus which was similar to that induced by the L-NAME. The increase of AT1 receptor mRNA levels in the hippocampus of immobilized rats was not further altered when the animals were pretreated with L-NAME. In control rats, exposure to immobilization resulted in a significant rise in mRNA levels coding for AT1 receptors in the hypothalamus, but not in the thalamus. L-NAME treatment showed a tendency of increase in AT1 receptor mRNA levels in the hypothalamus. Moreover, when animals treated with L-NAME were subjected to immobilization, a further increase in AT1 receptor mRNA levels was observed in the hypothalamus in comparison with corresponding controls.

CONCLUSIONS

The present data indicate that a single immobilization stress results in increased gene expression of AT1 receptors in the hypothalamus and hippocampus. The rise in AT1 mRNA levels in the same brain structures after repeated treatment with L-NAME allow to suggest an interaction between the central angiotensin II and nitric oxide.

Evidence that reduction of hepatocyte growth factor (HGF) is not required for peroxisome proliferator-induced hepatocyte proliferation

The mechanisms underlying peroxisome proliferator-induced hepatocarcinogenesis are not understood. Because of the uncertainty of human cancer risk associated with peroxisome proliferators, delineating the mechanisms of carcinogenesis by these agents is of great interest. Alterations in liver growth factors were postulated to contribute to the carcinogenic effect of peroxisome proliferators. Administration of these compounds to rodents results in down-regulation of hepatocyte growth factor (HGF) and supplementing culture medium with HGF is reported to suppress cell proliferation of preneoplastic and neoplastic cells from WY-14,643-treated livers. Combined, these observations suggest that reduced levels of hepatic HGF contribute to the mechanisms underlying peroxisome proliferator-induced hepatocarcinogenesis. To determine if HGF can prevent the effects of peroxisome proliferators in liver, the short-term influence of WY-14,643 in two different lines of HGF transgenic mice was examined. Mice were fed either a control diet or one containing 0.1% WY-14-643 for one week. Hepatomegaly was found in both HGF transgenic mouse lines fed WY-14,643 compared with controls. Additionally, hepatic expression of typical mRNA markers of peroxisome proliferation including those encoding peroxisomal fatty acid metabolizing enzymes and cell cycle control proteins were all significantly elevated in HGF transgenic mice fed WY-14,643 compared with controls. Down-regulation of HGF was found to be dependent on PPARalpha since lower levels of HGF mRNA and protein were observed in wild-type mice fed WY-14,643 for 1 week and not in similarly treated PPARalpha-null mice. These results demonstrate that the early increase in hepatic mRNAs associated with peroxisome and cell proliferation induced by WY-14,643 treatment can not be prevented by overexpression of HGF in vivo.

Covalent joining of the subunits of a homodimeric type II restriction endonuclease: single-chain PvuII endonuclease

The PvuII restriction endonuclease has been converted from its natural homodimeric form into a single polypeptide chain by tandemly linking the two subunits through a short peptide linker. The arrangement of the single-chain PvuII (sc PvuII) is (2-157)-GlySerGlyGly-(2-157), where (2-157) represents the amino acid residues of the enzyme subunit and GlySerGlyGly is the peptide linker. By introducing the corresponding tandem gene into Escherichia coli, PvuII endonuclease activity could be detected in functional in vivo assays. The sc enzyme was expressed at high level as a soluble protein. The purified enzyme was shown to have the molecular mass expected for the designed sc protein. Based on the DNA cleavage patterns obtained with different substrates, the cleavage specificity of the sc PvuII is indistinguishable from that of the wild-type (wt) enzyme. The sc enzyme binds specifically to the cognate DNA site under non-catalytic conditions, in the presence of Ca2+, with the expected 1:1 stoichiometry. Under standard catalytic conditions, the sc enzyme cleaves simultaneously the two DNA strands in a concerted manner. Steady-state kinetic parameters of DNA cleavage by the sc and wt PvuII showed that the sc enzyme is a potent, but somewhat less efficient catalyst; the k(cat)/K(M) values are 1.11 x 10(9) and 3.50 x 10(9) min(-1) M(-1) for the sc and wt enzyme, respectively. The activity decrease is due to the lower turnover number and to the lower substrate affinity. The sc arrangement provides a facile route to obtain asymmetrically modified heterodimeric enzymes.

Effect of myelopoietic and pleiotropic cytokines on colony formation by blast cells of children with acute lymphoblastic leukemia

The aim of this study was to see whether pleiotropic or myeloid hematopoietic growth factors, which do not stimulate normal lymphoid cells, can induce proliferation of blast cells of the acute lymphoid leukemia (ALL) of childhood. Bone marrow cells of 13 children with untreated ALL (nine common ALL, two myeloid antigen positive ALL and two early T-cell ALL) formed colonies of leukemic blast cells in primary methylcellulose cultures. Spontaneous growth was observed in three of 13 cases, whereas phytohemagglutinin-stimulated leukocyte conditioned medium (PHA-LCM), a conventional source of various natural human cytokines, induced colony formation in ten of 13 cases. A similar rate of responsiveness was seen with recombinant human granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF) and stem cell factor (SCF); a combination of these three cytokines induced colony formation in all cases studied. The effect of these growth factors on colony formation seemed to be dose-dependent in some cases. Of the stimuli studied, GM-CSF induced the smallest number of colonies, whereas the effects of G-CSF, SCF and PHA-LCM were similar in this respect. Combination of cytokines proved to be even more efficient in inducing clonal proliferation of leukemic lymphoblasts. In double combinations, G-CSF and GM-CSF as well as G-CSF and SCF were able to potentiate each other's effects. Triple combination of these cytokines mediated the most potent growth stimulus. Our results demonstrate that myeloid and pleiotropic cytokines are able to stimulate clonal proliferation of pediatric leukemic lymphoblasts. This may present a potential hazard to children with ALL while on adjuvant therapy with hematopoietic growth factors. In vitro colony assays performed prior to or in parallel with the administration of hematopoietic growth factors to ALL patients may help to forecast their possible effects on leukemic cells in vivo.

[Molecular biology examination in chronic lymphocytic leukemia]

Chronic lymphocytic leukaemia (CLL) is the most common adult leukaemia characterised by the accumulation of monoclonal CD5 + B-lymphocytes. The pathogenesis and the biology of CLL is complex and many details are still unknown. Several molecular biological methods have been used in the investigation of CLL, among them the study of apoptosis appears to be one of the most important. Initial experiences obtained by the spontaneous and fludarabine induced apoptosis, multidrug resistance (MDR)-test and fluorescent in situ hybridization (FISH) are reported by the authors. Apoptosis of CLL cells could be induced by fludarabine, while more studies should be performed to determine the exact role of MDR-test and FISH.

Calcein assay for multidrug resistance reliably predicts therapy response and survival rate in acute myeloid leukaemia

In this study, we evaluated the suitability of the calcein assay as a routine clinical laboratory method for the identification of multidrug-resistant phenotype in acute leukaemia. This study presents the results of the calcein tests obtained in two large haematological centres in Hungary. Assays were performed with blast cells of 93 de novo acute leukaemia patients, including 65 patients with acute myeloid leukaemia (AML). Results were expressed as multidrug resistance activity factor (MAF) values. AML patients were divided into responders and non-responders and MAF values were calculated for each group. In both centres, responder patients displayed significantly lower MAF values than non-responders (P = 0.0045 and P = 0.0454). Cut-off values were established between the MAFR + SEM and MAFNR - SEM values. On the basis of these cut-off levels, multidrug resistance (MDR) negativity showed a 72% predictive value for the response to chemotherapy, whereas MDR positivity was found to have an average predictive value of 69% for therapy failure. MDR activity was a prognostic factor for survival rate and the test was suitable for detecting patients at relapse. The calcein assay can be used as a quantitative, standardized, inexpensive screening test in a routine clinical laboratory setting. The assay detects both P-glycoprotein and multidrug resistance-associated protein activities, and identifies AML patients with unfavourable therapy responses.

The response of balanitis xerotica obliterans to local steroid application compared with placebo in children

PURPOSE

We evaluated the clinical effectiveness of topical steroid application for balanitis xerotica obliterans in children and analyzed the association of any clinical response with histological findings.

MATERIALS AND METHODS

Our double-blind, placebo controlled, randomized study included 40 boys in whom balanitis xerotica obliterans was diagnosed clinically by cicatricial phimosis. The severity of phimosis was graded into 4 groups. Patients were randomized to receive the topical application of 0.05% mometasone furoate or placebo. After 5 weeks phimosis severity was reevaluated and all patients underwent circumcision. Surgical specimens were histologically typed as an early, intermediate or late form of balanitis xerotica obliterans.

RESULTS

Seven patients were withdrawn from the study. In the steroid group 7 boys had clinical improvement and 10 had no change. Histological study showed an early, intermediate and late form of balanitis xerotica obliterans in 5, 5 and 7 cases, respectively. Of cases with clinical improvement 5 were the early and 2 the intermediate type. In the placebo group 5 cases worsened clinically and 11 did not change. Histological evaluation revealed an early, intermediate and late form of balanitis xerotica obliterans in 3, 7 and 6 boys, respectively. Of the 5 cases with histological worsening, disease was the early, intermediate and late type in 2, 2 and 1, respectively.

CONCLUSIONS

Applying a potent topical steroid affects improvement in balanitis xerotica obliterans in the histologically early and intermediate stages of disease, and may inhibit further worsening in the late stage.

Hepatitis viruses and hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is among the most frequent malignancies worldwide. Hepatitis viruses, such as the hepatitis B virus (HBV) and hepatitis C virus (HCV) are undoubtedly listed in the etiology of HCC. Studies show that, in the near future, viral hepatitis will carry increasing weight in the etiology of HCC. This review briefly discusses the known carcinogenic effects of HBV and HCV in the light of experimental and human studies. The data show that viral proteins may directly interfere with gene products responsible for cell proliferation and cell growth. Many other signal transduction cascades may be affected as well. Direct integration of HBV viral sequences into the host genome increases the genomic instability. The genomic imbalance allows the development and survival of malignant clones bearing defected genomic information. HBV and HCV infection induces indirect and direct mechanisms through cellular damage, increased regeneration and cell proliferation, therefore enhancing the development of HCC.

Corticotropin-releasing hormone mRNA levels in response to chronic mild stress rise in male but not in female rats while tyrosine hydroxylase mRNA levels decrease in both sexes

Corticotropin-releasing hormone (CRH) and catecholamines are suggested to play a significant role in the pathophysiology of depression. In the present study we investigated gene expression of CRH in the hypothalamic paraventricular nucleus (PVN) and tyrosine hydroxylase (TH) in the locus coeruleus (LC) in an experimental model of depression. A chronic mild stress model was applied in rats of both genders for a three-week period. Anhedonic behaviour, a typical sign of depression-like state, was measured by a sucrose preference test. The chronic mild stress induced a decrease in sucrose preference in both genders. The body weight gain was reduced in males only. The total activity in the open field test was unchanged, however, male rats exposed to chronic mild stress showed enhanced locomotor activity during the first minute of the session, suggesting increased anxiety. Basal plasma corticosterone levels, thymus and adrenal weights measured on the third day after cessation of the stress regimen, were not affected by the stress procedure. Evaluation of CRH mRNA levels in the PVN by in situ hybridisation revealed a significant rise in response to chronic mild stress in males. In females, the basal CRH mRNA levels were higher compared to those in males, but the stress-induced rise was absent. Chronic mild stress resulted in a decrease in TH mRNA levels in the LC. These data demonstrate that chronic mild stress model of depression induces a specific stress response with a reduction of TH gene expression in the LC and clear gender differences in gain of body weight, anxiety-like behaviour, and CRH mRNA levels in the PVN.

Daily profiles of arginine vasopressin mRNA in the suprachiasmatic, supraoptic and paraventricular nuclei of the rat hypothalamus under various photoperiods

Daily rhythm of arginine vasopressin (AVP) mRNA levels in the suprachiasmatic nucleus (SCN) of rats maintained under a short, LD 8:16 photoperiod differed from that of rats maintained under a long, LD 16:8 photoperiod: under the short photoperiod the morning AVP rise occurred significantly later than under the long one. Daily profiles of AVP mRNA in the supraoptic and paraventricular nuclei were not rhythmic and AVP mRNA levels under LD 8:16 did not differ from those under LD 16:8. The data indicate that photoperiod affects selectively the clock driven AVP gene expression in the SCN.

Molecular cloning and functional characterization of inhibitor-sensitive (mENT1) and inhibitor-resistant (mENT2) equilibrative nucleoside transporters from mouse brain

Mammalian cells express at least two subtypes of equilibrative nucleoside transporters, i.e. ENT1 and ENT2, which can be distinguished functionally by their sensitivity and resistance respectively to inhibition by nitrobenzylthioinosine. The ENT1 transporters exhibit distinctive species differences in their sensitivities to inhibition by dipyridamole, dilazep and draflazine (human>mouse>rat). A comparison of the ENT1 structures in the three species would facilitate the identification of the regions involved in the actions of these cardioprotective agents. We now report the molecular cloning and functional expression of the murine (m)ENT1 and mENT2 transporters. mENT1 and mENT2 encode proteins containing 458 and 456 residues respectively, with a predicted 11-transmembrane-domain topology. mENT1 has 88% and 78% amino acid identity with rat ENT1 and human ENT1 respectively; mENT2 is more highly conserved, with 94% and 88% identity with rat ENT2 and human ENT2 respectively. We have also isolated two additional distinct cDNAs that encode proteins similar to mENT1; these probably represent distinct mENT1 isoforms or alternative splicing products. One cDNA encodes a protein with two additional amino acids (designated mENT1b) that adds a potential protein kinase CK2 phosphorylation site in the central intracellular loop of the transporter, and is similar, in this regard, to the human and rat ENT1 orthologues. The other cDNA has a 5'-untranslated region sequence that is distinct from that of full-length mENT1. Microinjection of mENT1, mENT1b or mENT2 cRNA into Xenopus oocytes resulted in enhanced uptake of [(3)H]uridine by the oocytes relative to that seen in water-injected controls. mENT1-mediated, but not mENT2-mediated, [(3)H]uridine uptake was inhibited by nitrobenzylthioinosine and dilazep. Dipyridamole inhibited both mENT1 and mENT2, but was significantly more effective against mENT1. Adenosine inhibited both systems with a similar potency, as did a range of other purine and pyrimidine nucleosides. These results are compatible with the known characteristics of the native mENT1 and mENT2 transporters.

Role of alpha-1-adrenergic receptors in the regulation of corticotropin-releasing hormone mRNA in the paraventricular nucleus of the hypothalamus during stress

1. The role of alpha1-adrenergic receptors on CRH mRNA levels in the PVN was studied in control and stressed rats receiving i.c.v. injections of the alpha1-adrenergic agonist, methoxamine, or the alpha1- antagonist, prazosin. 2. Plasma ACTH increased significantly 60 min and 4 hr after a single injection of methoxamine (100 microg, i.c.v.). No desensitization of this response was observed after repeated injections every 6 hr for 24 hr. Concomitantly, POMC mRNA in the anterior pituitary increased by 25% at 4 hr after a single injection and by 96% after repeated injections. 3. CRH mRNA levels in the PVN increased by 131% after repeated injections for 24 hr, but were unchanged 4 hr after a single injection. Central alpha-adrenergic blockade with prazosin did not prevent the increases in CRH mRNA following 4 hr of acute stress, but significantly reduced the increases observed 24 hr after an i.c.v. injection of 75 microg of colchicine or after repeated i.p. hypertonic saline injections every 8 hr. 4. These studies demonstrate that while alpha1-adrenergic receptors contribute to longterm increases of CRH mRNA levels in the PVN during prolonged stress, other factors are likely to be involved in the stimulation of CRH mRNA following acute stimulation.