Reduction of ischemic damage by application of insulin-like growth factor-1 in rat brain after transient ischemia

In order to investigate a possible effect of insulin-like growth factor-1 (IGF-1) on ischemic brain injury, IGF-1 was applied topically on the brain surface of reperfused rat brain after 60 min of transient middle cerebral artery occlusion. In contrast to the cases treated with vehicle, the infarct volume was greatly reduced at 24 h of reperfusion by the treatment with IGF-1. Immunohistochemical analysis in the middle cerebral artery territory showed that Caspase-3 staining was markedly reduced in the cases with IGF-1 treatment, but 72-kDa heat shock protein staining remained almost unchanged. The present results suggest that treatment with IGF-1 exerts a significant effect on ameliorating brain injury after transient focal brain ischemia. Moreover, this effect is greatly associated with the reduction of Caspase-3 staining, but is only minimally associated with a decreasd stress response at the cellular level.

Increased secretion of tumour necrosis factor and interleukin 6 from isolated, perfused liver of rats after partial hepatectomy

The present study explored the changes in hepatic secretion of tumour necrosis factor (TNF) and interleukin 6 (IL-6) during the regenerative process of the liver, focusing on the role of Kupffer cells. The secretions of TNF and IL-6 from the perfused rat liver were increased after 67% partial hepatectomy, reaching a maximum at 48 h. The response of cytokine secretion induced by lipopolysaccharide (LPS: 1 microgram/ml) was also potentiated in regenerating liver. The secretion of TNF, but not that of IL-6, induced by LPS was almost totally suppressed by pretreatment of rats with gadolinium chloride, which depletes Kupffer cells. These results indicate that hepatic secretions of TNF and IL-6 are increased during the regenerative process of the liver. Kupffer cells play an important role in hepatic secretion of TNF, whereas the production of IL-6 can be achieved by other cells of the liver.

Chemotherapy-induced unconjugated hyperbilirubinemia caused by a mutation of the bilirubin uridine-5'-diphosphate-glucuronosyltransferase gene

Chemotherapy for malignant neoplasms sometimes causes unconjugated hyperbilirubinemia in the absence of liver dysfunction. We analyzed the association of chemotherapy-induced hyperbilirubinemia with mutations of the bilirubin uridine-5'-diphosphate (UDP)-glucuronosyltransferase gene (UGT1A1) from two leukemic patients in whom chemotherapy resulted in a hyperbilirubinemic response. We isolated genomic DNA from peripheral blood samples and amplified UGT1A1 by polymerase chain reaction. The amplified DNA fragments were analyzed by direct sequencing. The genes of the two patients revealed an identical heterozygous missense mutation in exon 1 (211G-->A: G71R). This UGT1A1 mutation may be the basis of chemotherapy-induced unconjugated hyperbilirubinemia.

ATRAP, novel AT1 receptor associated protein, enhances internalization of AT1 receptor and inhibits vascular smooth muscle cell growth

We have identified a novel, membrane-located protein that interacts specifically with the carboxyl-terminal cytoplasmic domain of the AT1a receptor, which we named ATRAP (for AT1 receptor-associated protein). To further investigate the role of ATRAP in AT1 receptor function, we examined the effect of overexpression of ATRAP on angiotensin II (Ang II)-induced AT1 receptor desensitization and/or internalization, and cell proliferation in adult vascular smooth muscle cells (VSMCs). Transfection of ATRAP potentiated AT1 receptor internalization upon Ang II stimulation in these VSMCs. Moreover, we observed that AT1 receptor-induced DNA synthesis was markedly inhibited in ATRAP transfected VSMCs associated with the inhibition of the phosphorylation of signal transducers and activators of transcription (STAT) 3 and Akt. Our results suggest that ATRAP functions as a negative regulator in AT1 receptor-mediated cell proliferation in VSMCs.

Inhibitory effect of angiotensin II type 2 receptor on coronary arterial remodeling after aortic banding in mice

BACKGROUND

The renin-angiotensin system is thought to be critical for the development of cardiac hypertrophy, whereas the role of the angiotensin II type 2 (AT(2)) receptor in the process is not defined. Using the AT(2) receptor-null (Agtr2-) mouse, we tested the hypothesis that the AT(2) receptor could exert an antigrowth effect in cardiac hypertrophy.

METHODS AND RESULTS

Cardiac hypertrophy was induced by suprarenal abdominal aortic banding in 10- to 12-week-old Agtr2- and wild-type (Agtr2+) mice for 6 or 12 weeks. Carotid arterial pressure was not different between the strains, although aortic banding increased arterial pressure by approximately 40 mm Hg. Aortic banding increased the heart-weight/body-weight ratio and the cross-sectional area of cardiomyocytes by 15%, resulting in comparable cardiomyocyte hypertrophy in the 2 strains. In contrast, coronary arterial thickening and perivascular fibrosis, determined by the media/lumen-area ratio and the collagen/vessel-area ratio, respectively, were 50% greater in Agtr2- than in Agtr2+ mice after banding, whereas these parameters were similar in sham-operated mice. Radioligand binding studies using the whole heart and immunohistochemistry showed that AT(2) receptor expression was limited and localized in the coronary artery and perivascular region.

CONCLUSIONS

These results suggest that the AT(2) receptor mediates an inhibitory effect on coronary arterial remodeling, such as medial hypertrophy and perivascular fibrosis in response to pressure overload, and an activation of the renin-angiotensin system.

Direct identification of a novel disulfide bond linkage system of new isolated isomer (isomer V) in recombinantly produced h-IGF-I

Insulin-like growth factor I (IGF-I or somatomedin C) is a serum polypeptide with three intramolecular disulfide bonds. In the course of synthesis by the recombinant DNA method, three disulfide bond isomers, all of which have Cys18-Cys61 with three combinations of two disulfide bonds formed by Cys6, Cys47, Cys48 and Cys52, were identified. Natural type, isomer II, was proved to have a Cys6-Cys48, Cys18-Cys61, Cys47-Cys52 disulfide bond system. Now, the fourth isomer, isomer V which doesn't have Cys18-Cys61 disulfide, has been isolated, and its novel disulfide bond linkage system was identified by a chemical synthetic method. The supposed conformation constrained in 3D structure for isomer V would be discussed for its biological activity.

Targeted killing of carcinoembryonic antigen (CEA)-producing cholangiocarcinoma cells by polyamidoamine dendrimer-mediated transfer of an Epstein-Barr virus (EBV)-based plasmid vector carrying the CEA promoter

The present study reports a novel nonviral method to efficiently and specifically target carcinoembryonic antigen (CEA)-producing cholangiocarcinoma (CC) cells in vitro. Epstein-Barr virus (EBV)-based and conventional plasmid vectors were constructed that possess the beta-galactosidase (beta-gal) or herpes simplex virus-1 (HSV-1) thymidine kinase (Tk) genes as well as tandem repeats of the human genomic sequence -82 to -42 bp from the transcriptional start site of the CEA gene. The plasmids were transfected by means of polyamidoamine dendrimer into CEA-positive (HuCC-T1) or -negative cell lines. Transfection of the conventional plasmid vector with the CEA promoter and beta-gal gene resulted in a very low or undetectable level of marker gene expression even in the CEA-positive cell line. Transferring the HSV-1 Tk gene by conventional plasmid did not affect the susceptibility of HuCC-T1 cells to ganciclovir. In marked contrast, strong beta-gal expression was specifically obtained in HuCC-T1 cells by transfecting the EBV-based plasmid in which the CEA promoter and a ubiquitous promoter (SRalpha) are employed to drive the EBV-encoded nuclear antigen 1 (EBNA1) and beta-gal genes, respectively (pTES.beta). Furthermore, CEA-positive but not -negative tumor cells were rendered highly susceptible to ganciclovir when transfected with the EBV-based vector that carries the CEA promoter-EBNA1 and SRalpha-HSV-1 Tk genes (pTES.Tk). These results strongly suggest that the EBV-based plasmid vector/cationic polymer system (EBV/polyplex) equipped with the CEA promoter provides an efficient nonviral method for the targeted gene therapy of CEA-producing malignancies.

Prediction of embolism in atrial fibrillation: classification of left atrial thrombi by transesophageal echocardiography

The current study was undertaken to clarify the relationship between cerebral/arterial embolism and the morphology of left atrial thrombi. Forty-one patients with atrial fibrillation and left atrial thrombi were followed for 1 year, using transesophageal echocardiography (TEE) to study how the shape, site, movability, number and maximum dimension of left atrial thrombi are related to embolism. Left atrial thrombi were classified by their shape and movability into movable ball (MB) type (n=13), fixed ball (FB) type (n=17) and mountain (MN) type (n=11). The thrombi were also classified by location into the interior section (n=3), middle section (n=8), and the entrance section (n=19) of the left atrial appendage, and the section outside of the left atrial appendage (n=11). The rate of embolism in the MB-type group was significantly higher than that in the other groups (ie, MB 76.9% vs FB 17.6% (p<0.01) vs MN 9.1%; p<0.01), which indicates that the MB-type thrombus is an important risk factor for cerebral/arterial embolism.

Aggravation of chemically-induced injury in perfused rat liver by extracellular ATP

The effects of purinergic receptor agonists on acute liver damage and hemodynamics were studied using chemically-induced liver injury. Rat livers were perfused in situ 24 h after treatment with D-galactosamine (800 mg/kg, i.p.). In these livers, infusion of ATP (50 microM) into the portal vein caused a rapid increase in the leakage of LDH and AST from perfused liver in a dose dependent manner, accompanied with flow reduction. The similar but less effective responses were also observed by the infusion of ADP. Infusion of adenosine, a P1-receptor agonist, induced only minimal changes of liver damage and flow rate. The ATP-induced changes were almost completely suppressed by P2-receptor antagonist, suramin, but not affected by P1-receptor antagonist, 8-phenyltheophylline. Pretreatment of rats with gadolinium chloride, which depletes Kupffer cells, did not inhibit the potentiation of liver damage caused by ATP, whereas hemodynamic effects of ATP were significantly attenuated by gadolinium. These results indicate that extracellular ATP aggravates acute liver injury mediated by P2-type purinergic receptors.

Isolation and cDNA-derived amino acid sequences of hemoglobin and myoglobin from the deep-sea clam Calyptogena kaikoi

The heterodont clam Calyptogena kaikoi, living in the cold-seep area at a depth of 3761 m of the Nankai Trough, Japan, has abundant hemoglobins and myoglobins in erythrocytes and adductor muscle, respectively. Two types of hemoglobins (Hb I and Hb II) were isolated, and the complete amino acid sequences of Hb I (145 residues) and Hb II (137 residues) were obtained with combination of cDNA and protein sequencing. The amino acid sequences of C. kaikoi Hbs I and II differed from homologous chains of the congeneric clam Calyptogena soyoae in eight and five positions, respectively. The distal (E7) His, one of the functionally important residues in hemoglobin and myoglobin, was replaced by Gln in hemoglobins of C. kaikoi. A phylogenetic analysis of clam hemoglobins indicates that the evolutionary rate of Calyptogena hemoglobins is rather faster than those of other clams, suggesting that the mutation rate might be accelerated in the deep-sea animals around the areas of cold seeps or hydrothermal vents. On the other hand, it was found unexpectedly that two myoglobins Mbs I and II, isolated from the red adductor muscle, are identical in amino acid sequence Hbs I and II, respectively. Thus it was assumed that genes for Hbs I and II are also expressed in the muscle of C. kaikoi in substitution for myoglobin gene. This suggests that the major physiological role of globins in C. kaikoi is storage of oxygen under the low oxygen conditions, rather than circulating of oxygen.

Interferon-gamma induces AT(2) receptor expression in fibroblasts by Jak/STAT pathway and interferon regulatory factor-1

The expression of angiotensin II type 2 (AT(2)) receptor is closely associated with cell growth, differentiation, and/or injury. We examined the effect of interferon (IFN)-gamma on AT(2) receptor expression in mouse fibroblast R3T3 cells and demonstrated that IFN-gamma treatment increased the expression of AT(2) receptor mRNA as well as its binding. Interferon regulatory factor (IRF)-1 was induced in mouse fibroblast R3T3 cells after IFN-gamma stimulation, and electrophoretic mobility shift assay showed an increase in IRF-1 binding with the IRF-specific binding sequence in the AT(2) receptor gene promoter region after IFN-gamma stimulation. The IRF-1 gene promoter contains an IFN-gamma-activated sequence (GAS) motif for possible binding of signal transducer(s) and activator(s) of transcription (STAT). Indeed, in R3T3 cells, IFN-gamma treatment resulted in rapid activation of Janus kinase (Jak) 1, Jak2, and STAT1 via tyrosine phosphorylation. Electrophoretic mobility shift assay with the GAS probe revealed increased STAT1 binding to the IRF-1 gene promoter in response to IFN-gamma stimulation. Transfection of GAS-binding oligonucleotides inhibited the effect of IFN-gamma on IRF-1 production, resulting in the AT(2) receptor trans-activation. Taken together, our data show that IFN-gamma upregulates AT(2) receptor expression in R3T3 cells via the activation of the intracellular Jak/STAT pathway and production of IRF-1.

Effective suicide gene therapy in vivo by EBV-based plasmid vector coupled with polyamidoamine dendrimer

This study demonstrates in vivo effectiveness of a nonviral vector system, Epstein-Barr virus (EBV)-based plasmid vector coupled with polyamidoamine (PAMAM) dendrimer (EBV/polyplex), in suicide gene therapy of cancer. The EBV-based vector is a plasmid vector containing EBV nuclear antigen 1 (EBNA1) gene and oriP from EBV genome. HSV-1 tk gene was transferred into Ewing's sarcoma cell lines, A4573 and KP-EWS-YI, by using an EBV-based plasmid vector, pSES.Tk, or a conventional plasmid vector, pS.Tk. Cells transfected with pSES.Tk/dendrimer showed approximately 100 times lower ID50 to ganciclovir (GCV) compared with those transfected with pS. Tk/dendrimer. Intratumoral injection of pSES.Tk/dendrimer but not pS. Tk/dendrimer drastically suppressed the growth of tumors which had generated from A4573 or Huh7 hepatocellular carcinoma (HCC) cells inoculated into severe combined immunodeficiency (SCID) mice. The treatment with pSES.Tk/dendrimer also resulted in significant prolongation of survival of the mice implanted with A4573. These results suggest that the EBV/polyplex system could be useful for in vivo suicide gene therapy of cancer. Gene Therapy (2000) 7, 53-60.

Highly efficient suicide gene expression in hepatocellular carcinoma cells by epstein-barr virus-based plasmid vectors combined with polyamidoamine dendrimer

The present study was aimed at devising an efficient nonviral strategy for suicide gene therapy of hepatocellular carcinoma (HCC). To improve the efficiency of DNA delivery and expression, we applied Epstein-Barr virus (EBV)-based plasmid vectors instead of conventional plasmid vectors and combined them with cationic liposome (EBV/lipoplex) or polyamidoamine dendrimer (PAAD) (EBV/polyplex). When the beta-galactosidase gene was transferred to HuH7, PLC/PRF/5, or HLE cells, < or =50-fold higher beta-galactosidase activities were demonstrated in the cells transfected with EBV vector compared with those transfected with conventional plasmid vectors. PAAD-mediated transfection of HCC with pSES.Tk (an EBV-based vector carrying the herpes simplex virus-1 thymidine kinase gene) resulted in a marked reduction in viable cell number by the addition of ganciclovir (GCV). The HCC cells transfected with pSES.Tk/PAAD showed 100- to 1000-fold higher susceptibilities to GCV than those transfected with pS.Tk (a conventional plasmid vector carrying herpes simplex virus-1 thymidine kinase gene)/PAAD. The pSES.Tk-transfected HCC cells were effectively killed by day 9 in culture with a clinically feasible concentration of GCV (25 microM), whereas the pS.Tk-transfected cells survived the culture. These results demonstrate highly efficient suicide gene transfer into various HCC cells by EBV-based plasmid vectors in vitro, suggesting the possible application of this nonviral vector system to gene therapy of HCC.

Development of gap junctional channels and intercellular communication in rat liver during ontogenesis

BACKGROUND/AIMS

We investigated the expression of connexin (Cx) 32 and 26 subunit proteins of the gap junction (GJ) in the rat liver during ontogenesis to clarify their roles in control of growth and differentiation, and observed their channels in association with development of gap junctional intercellular communication (GJIC).

METHODS

The expression of Cx32 and 26 in prenatal and postnatal livers was examined by Western blot and immunofluorescence. GJ channels were investigated not only by double immunofluorescence study but also by immunogold electron microscopy. The spread of lucifer yellow 5 min after its microinjection was examined in the cultured liver tissues.

RESULTS

1) Western blot showed the expression of both Cx from the late stage of gestation and their peak a week after birth. 2) Cx32- or 26-positive plaques were scattered on hepatocytes of the fetal liver and some of them were colocalized; both were increased just after birth. On day 7 after birth, Cx32-positive plaques were present on all hepatocytes within a lobule, and Cx26-positive plaques were distributed in the periportal area. 3) Double-immunogold electron microscopy just after birth showed that most GJ channels were homotypic type of Cx32 or 26, and that few were heterotypic. On day 7 after birth, most channels had the homotypic type of type of Cx32 in the middle and pericentral areas, and there was a heterotypic type of Cx32 and 26 in the periportal area. 4) The dye transfer of lucifer yellow showed a wider spread in the liver tissues on day 7 after birth than on day 1.

CONCLUSION

Increased GJ formation and compatibility or incompatibility of GJ channels are closely associated with development of GJIC, and GJIC may develop at cytodifferentiation during ontogenesis.

[Effect of bufalin on growth and differentiation of human skin carcinoma cells in vitro]

Bufalin, a cardiotonic steroid isolated from the Chinese toad, was previously shown to have growth inhibitory and differentiation inducing activities on leukemia cells and malignant melanoma cells. We examined the effect of bufalin on growth and differentiation of human skin squamous cell carcinoma cells (SSCC-1) in vitro. The concentration needed for growth inhibition of SSCC-1 cells was 10(-8) M, which was lower than those of gamabufotalin and ouabain. When SSCC-1 cells were treated with 10(-8) M bufalin for 16 h, the DNA synthesis of SSCC-1 cells decreased, but there was no change in their survival ratio. The results suggest that growth inhibitory effect of buffalin is not only a cytotoxic effect. Bufalin increased the production of cornified envelopes and the expression of Keratin K10/11 and involurcin. These findings indicate that bufalin has both growth inhibitory and differentiation inducing effects on SSCC-1 cells.

Receptor subtype mediating the action of circulating endothelin on glucose metabolism and hemodynamics in perfused rat liver

The subtype of endothelin receptor that mediates metabolic and hemodynamic effects of circulating endothelin was explored using perfused rat liver. Infusion of endothelin (ET)-1 or ET-3 into the portal vein at a concentration of 0.3 nM increased glucose and lactate output and decreased perfusion flow, although ET-3 was less effective than ET-1. The metabolic effects of ET-1 were observed even under costant-flow perfusion. Infusion of either sarafotoxin S6b or S6c, an ET(A)- or ET(B)-receptor agonist, mimicked the actions of ET-1 to an equal extent. The flow reduction and glucose production induced by ET-1 were partly attenuated by the ET(A)-receptor antagonist BQ485. By contrast, ET(B)-receptor antagonist BQ788 enhanced glucose production caused by ET-1 and ET-3 without affecting the hemodynamic change. The effects of ET-1 and ET-3 were almost totally inhibited by the combination of BQ485 and BQ788. These results suggest that both ET(A) and ET(B) receptors are involved in the metabolic and hemodynamic effects of circulating endothelin in rat liver, while the ET(A)-receptor-mediated action appears to be dominant.

Role of the sympathetic nervous system and insulin in enhancing glucose uptake in peripheral tissues after intrahypothalamic injection of leptin in rats

Our previous study demonstrated that microinjection of leptin into the ventromedial hypothalamus (VMH) dramatically increased glucose uptake in the heart, brown adipose tissue (BAT), and skeletal muscles, but not in white adipose tissue (WAT) in conscious unrestrained rats, as assessed in vivo by the 2-[3H]deoxyglucose method. Here we examined the role of the sympathetic nervous system and insulin in enhanced glucose uptake by tissues after hypothalamic leptin injection. Pretreatment with guanethidine significantly suppressed the increased glucose uptake by the tissues in response to leptin injected into the VMH, whereas bilateral adrenal demedullation had no significant effect. Treatment with propranolol but not phenoxybenzamine also decreased significantly enhanced glucose uptake by the tissues. We further examined the interaction of the effects of hypothalamic leptin and insulin administered peripherally by clamping the glucose concentrations at a constant level. When leptin was injected into the VMH and a maximal dose of insulin was administered intravenously, the rates of glucose uptake by the heart, BAT, and skeletal muscles, but not by WAT, markedly increased beyond the values reached by insulin stimulation alone. Surgical sympathetic denervation of BAT abolished the enhancement of glucose uptake in this tissue, decreasing to the level stimulated by insulin alone. These results appear to indicate that leptin in the hypothalamus enhances glucose uptake in certain peripheral tissues through mediation of a beta-adrenergic mechanism for the sympathetic nerves innervating the tissues and that central leptin and peripheral insulin have a synergistic role in augmenting tissue glucose uptake.

Autoantibodies to FK506 binding protein 12 (FKBP12) in autoimmune diseases

Plasma from 126 patients with various autoimmune diseases and 118 healthy subjects were examined to determine the presence of autoantibodies to FKBP12, one of immunophilins. The frequency of IgG and/or IgM anti-FKBP12 autoantibodies detected by ELISA was as follows; SLE (15/39), SSc (11/27), CREST (4/7), RA (2/8), MCTD (0/5), Graves' disease (4/12), IDDM (2/6), PM/DM (0/3), MG (1/4), AIH (2/6), PBC (4/9), and healthy subjects (5/118). The specificity of the autoantibodies was demonstrated by absorption of the plasma samples with r-FKBP12 and other recombinant proteins. In immunoblotting, IgM anti-FKBP12 autoantibodies reacted with two bands of 12 and 24 kD, the latter representing the dimer. Anti-FKBP12 autoantibodies in some patients reacted more strongly with the dimer than the monomer, suggesting that FKBP12 may also exist as the dimer in vivo. The majority of anti-FKBP12 autoantibodies bound to two synthetic peptides corresponding to amino acid residues of FKBP12, Pro16 approximate to Tyr26 and Thr27 approximate to Phe46. These epitopes are phylogenetically well conserved and responsible for the binding to calcineurin and FK506. The autoantibodies inhibited pentamerization of FKBP12 with FK506, calcineurin, calmodulin, and Ca2+ in vitro. These data define the frequent occurrence of a novel set of autoantibodies to a cytosolic protein involved in the regulation of the immune response.

Cross talk between angiotensin II type 1 and type 2 receptors: cellular mechanism of angiotensin type 2 receptor-mediated cell growth inhibition

Angiotensin (Ang) II plays an important role in regulating cardiovascular hemodynamics as well as cardiovascular structure. At least two distinct receptor subtypes of Ang II have been defined on the basis of their differential pharmacological and biochemical properties, and designated as Ang II type 1 (AT1) receptor and type 2 (AT2) receptor. Most of the known effects of Ang II in adult tissues are attributable to the AT1 receptor. Recent cloning of the AT2 receptor has revealed a variety of new physiological effects of Ang II. AT1 and AT2 receptors belong to the seven-transmembrane receptor family. However, the function and signaling mechanism of these receptor subtypes are quite different. These receptors seem to exert opposite effects in terms of cardiovascular hemodynamics and cell growth. Growth inhibitory effects of AT2 receptors are unique in that this receptor activates a variety of phosphatases and cross talks with the signaling of other seven-transmembrane, G protein-coupled receptors, as well as other classes of growth factor receptors. We will review recent concepts of the molecular and cellular mechanisms of AT2 receptor action in this article.

Cloning, expression of the psbU gene, and functional studies of the recombinant 12-kDa protein of photosystem II from a red alga Cyanidium caldarium

The encoding extrinsic 12-kDa protein of oxygen-evolving PS II complex from a red alga, Cyanidium caldarium, was cloned and sequenced by means of PCR and a rapid amplification of cDNA ends (RACE) procedure. The gene encodes a putative polypeptide of 154 amino acids with a calculated molecular mass of 16,714 Da. The full sequence of the protein includes two characteristic transit peptides, one for transfer across the chloroplast envelope and another for targeting into the thylakoid lumen. This indicates that the protein is encoded in the nuclear genome. The mature protein consists of 93 amino acids with a calculated molecular mass of 10,513 Da. The cloned gene was successfully expressed in Escherichia coli and the resulting protein was purified, reconstituted to CaCl2-washed PS II complex together with the other extrinsic proteins of 33 and 20 kDa and cyt c-550. The recombinant 12-kDa protein bound completely with the PSII complex, which resulted in a restoration of oxygen evolution equal to the level achieved by binding of the native 12-kDa protein.

[High prevalence of TT virus(TTV) in patients with non A to non G fulminant hepatitis: differences of clinical features and prognosis between TTV positive and negative patients]

We detected TTV-DNA in sera from 36 patients with fulminant hepatitis(FH) and evaluated differences in clinical features and prognosis between TTV-DNA positive and negative patients with nonA-nonG FH. TTV-DNA in sera was measured by nested PCR. Twenty of 36 patients with FH were diagnosed nonA-nonG FH. The TTV-DNA in sera was detected in 14 patients(38.9%) with FH, 9(64%) showed nonA-nonG FH and 3 were HBV FH and 2 were drug-induced FH. Although we compared clinical features(gender, age, distribution history of blood transfusion, initial symptoms of hepatitis, and liver function tests) and prognosis between TTV positive and negative patients with nonA-nonG FH, there were no significant differences between the two groups. These data suggest that although TTV may be a infectious agent related to nonA-nonG FH, further study is needed to clarify the role of TTV in the pathogenesis of FH.

Enhancement of membrane-type 1-matrix metalloproteinase (MT1-MMP) production and sequential activation of progelatinase A on human squamous carcinoma cells co-cultured with human dermal fibroblasts

Matrix metalloproteinase 2 (MMP-2)/gelatinase A plays an important role in tumour invasion and metastasis. Since MMP-2 is secreted as an inactive form (proMMP-2) from tumour and neighbouring stroma cells, the activation process is necessary to express the enzymic activity for degradation of extracellular matrix components. We herein reported that the activation of proMMP-2 was induced in human squamous carcinoma cells co-cultured with normal human dermal fibroblasts. When A431 cells were co-cultured with human fibroblasts at various cell ratios, 72-kDa proMMP-2 was converted to a 62-kDa active form through the appearance of a 64-kDa intermediate. The activation of proMMP-2 by co-culture was also observed in other carcinoma cell lines, HSC-4 and SAS, but not in normal human keratinocytes. We characterized by in vitro invasion assay that A431 cells in co-culture preferentially invaded through Matrigel and the increased invasive activity was inhibited by exogenously adding tissue inhibitor of metalloproteinases 2. The augmented proMMP-2 activation by co-culture was achieved by the increase in membrane type 1-MMP (MT1-MMP) production along with that of its mRNA level. The predominant appearance of MT1-MMP was immunologically observed in A431 cells, but not human fibroblasts of the co-culture. Furthermore, epidermal growth factor (EGF) enhanced the co-culture-mediated proMMP-2 activation by increasing the production and gene expression of MT1-MMP, and thereby tumour invasive activity was further augmented. These results suggest that the cell-cell contact between carcinoma cells and normal fibroblasts enhances the production of MT1-MMP followed by sequential activation of proMMP-2 on the tumour cell surface, which may be closely implicated in tumour invasion in vivo.