Biomedical subjects

S Seki

Publications and source records attributed to S Seki.

At least 73 records · Page 4Linked to original sources

PubMed2001

Telomerase activation and MAPK pathways in regenerating hepatocytes.

Although there have been many reports on the relationship between the activation of telomerase and carcinogenesis, the role of telomerase in normal cellular growth is still unclear. Recently, the telomerase upregulation during the process of liver regeneration has been reported, but the precise time course of its activity and factors contributing to the activation of telomerase have not yet been fully elucidated. In the present review, we demonstrate the relationship between the activation of the telomerase, the cell cycle progression and the growth-related signaling during the liver regeneration process using an in vivo mouse partial hepatectomy model. Moreover, the importance of the role of the MAPK pathways on the telomerase activity in regenerating hepatocytes is also displayed by using an in vitro culture model. In conclusion, the telomerase activity is upregulated before hepatocytes enter the S phase, and some growth factors such as EGF and HGF contribute to this process. The activation of the growth-related signaling pathways seems to play essential roles in the upregulation of the telomerase activity.

Animals↗

PubMed2000

Comparison of substrate specificities of Escherichia coli endonuclease III and its mouse homologue (mNTH1) using defined oligonucleotide substrates.

Escherichia coli endonuclease III (Endo III) and its eukaryotic homologues are major repair enzymes for pyrimidine lesions formed by reactive oxygen species and ionizing radiation. In the present study, the activities of Endo III and its mouse homologue (mNTH1) have been compared using defined oligonucleotide substrates containing a urea residue (UR), two cis-thymine glycol (TG) diastereoisomers, 5, 6-dihydrothymine (DHT), and 5-hydroxyuracil (HOU). The substrates were incubated with Endo III and mNTH1, and their activities were compared based on the product analysis by gel electrophoresis. Endo III recognized all base lesions tested, but the activity for DHT was extremely lower than other substrates. In contrast, albeit some preference of UR, mNTH1 showed essentially comparable activities for all substrates including DHT. Comparison of the enzymatic parameters for cis-TG and DHT revealed that large decreases in the affinity (K(m), 27-fold) and k(cat) (11-fold) relative to cis-TG made DHT an very poor substrate for Endo III. mNTH1 had comparable affinities and k(cat) for both cis-TG and DHT, though turnover (k(cat)) of mNTH1 was notably slower than Endo III. In view of the reaction mechanism, the paired base effect on the damage recognition by the two enzymes was also examined. The activities of Endo III for UR and HOU were paired base-independent, but those for cis-TG and DHT were significantly enhanced when paired with G. With mNTH1, the paired base effect was evident only for DHT. The variations of the repair activity with paired bases and enzymes are discussed in relation to the base flipping mechanism suggested for base excision repair enzymes.

Animals↗

PubMed2000

Recognition of formamidopyrimidine by Escherichia coli and mammalian thymine glycol glycosylases. Distinctive paired base effects and biological and mechanistic implications.

The activity of prokaryotic and mammalian thymine glycol (Tg) glycosylases including Escherichia coli endonuclease III (Endo III) and endonuclease VIII (Endo VIII) and mouse Endo III homologue (mNth1) for formamidopyrimidine (Fapy) has been investigated using defined oligonucleotide substrates. 2, 6-Diamino-4-hydroxy-5-N-methylformamidopyrimidine, a methylated Fapy derived from guanine, was site specifically incorporated in the oligonucleotide. The substrates containing Fapy:N pairs (N = A, G, C, T) as well as a Tg:A pair, a physiological substrate of Endo III, Endo VIII, and mNth1, were treated by the enzymes and nicked products were quantified by gel electrophoresis. The activity of Endo III and Endo VIII for Fapy varied markedly depending on the paired base, being the highest with G (activity relative to Tg = 0. 55 (Endo III) and 0.41 (Endo VIII)) and the lowest with C (0.05 (Endo III) and 0.06 (Endo VIII)). In contrast, mNth1 recognized all Fapy pairs equally well and the activity was comparable to Tg. The results obtained in the nicking assay were further substantiated by the analysis of the Schiff base intermediate using NaBH(4) trapping assays. These results indicate that Escherichia coli and mammalian Tg glycosylases have a potential activity to recognize Fapy. However, as demonstrated for Fapy:C pairs, their distinctive activities implicate unequal participation in the repair of Fapy lesions in cells.

Animals↗

PubMed2000

Identification of functional elements in the bidirectional promoter of the mouse Nthl1 and Tsc2 genes.

The gene of mammalian endonuclease III homologs (NTHL1/Nthl1), a DNA glycosylase/AP lyase involved in base excision repair, lies immediately adjacent to one of the tuberous sclerosis disease-determining genes, TSC2/Tsc2, in a head-to-head orientation. To clarify the regulation of these divergent genes, we studied the promoter activities of these transcription units by luciferase assay using HeLa cells. We found that the short spacer sequence of 63 base pairs (bp) between the mouse Nthl1 and Tsc2 genes shows bidirectional promoter activity essential for the transcription of both genes. The 63-bp sequence is well conserved among several mammalian species and contains two Ets-transcription factor binding sites (EBSs) in opposite directions. An Ets-family protein in the HeLa nuclear extract specifically bound to either EBSs. Mutation of the core motif of the EBS demonstrated that EBS positively regulates transcription of both mNthl1 and mTsc2 genes. These EBSs had an additive effect on transcription, and each EBS functioned equally in both directions.

Animals↗

PubMed2000

Mouse CD8+ CD122+ T cells with intermediate TCR increasing with age provide a source of early IFN-gamma production.

Although CD8+ IL-2Rbeta (CD122)+ T cells with intermediate TCR reportedly develop extrathymically, their functions still remain largely unknown. In the present study, we characterized the function of CD8+ CD122+ T cells with intermediate TCR of C57BL/6 mice. The proportion of CD8+ CD122+ T cells in splenocytes gradually increased with age, whereas CD8+ IL-2Rbeta-negative or -low (CD122-) T cells conversely decreased. The IFN-gamma production from splenocytes stimulated with immobilized anti-CD3 Ab in vitro increased with age, whereas the IL-4 production decreased. When sorted CD8+ CD122+ T cells were stimulated in vitro by the anti-CD3 Ab, they promptly produced a much larger amount of IFN-gamma than did CD8+ CD122- T cells or CD4+ T cells, whereas only CD4+ T cells produced IL-4. The depletion of CD8+ CD122+ T cells from whole splenocytes greatly decreased the CD3-stimulated IFN-gamma production and increased the IL-4 production, whereas the addition of sorted CD8+ CD122+ T cells to CD8+ CD122+ T cell-depleted splenocytes restored the IFN-gamma production and partially decreased IL-4 production. It is of interest that CD8+ CD122+ T cells stimulated CD4+ T cells to produce IFN-gamma. The CD3-stimulated IFN-gamma production from each T cell subset was augmented by macrophages. Furthermore, CD3-stimulated CD8+ CD122+ T cells produced an even greater amount of IFN-gamma than did liver NK1.1+ T cells and also showed antitumor cytotoxicity. These results show that CD8+ CD122+ T cells may thus be an important source of early IFN-gamma production and are suggested to be involved in the immunological changes with aging.

Aging↗

PubMed2000

TT virus infection in patients with chronic liver disease of unknown etiology.

The role of a novel virus, designated as TT virus (TTV), as a cause of chronic liver disease has not been well defined. We investigated the prevalence of TTV among 69 patients with chronic liver disease of unknown etiology and 50 volunteer blood donors with normal transaminase levels. TTV DNA was amplified by polymerase chain reaction (PCR) by using two different sets of primers: one based on the sequence of the original N22 clone within the open reading frame 1 (set A) and the other derived from the untranslated region (set B). The prevalence of TTV detected by PCR primers set A only, set B only, and in total (by either set A or B) was 11 (31%), 31 (86%), and 31 (86%) of 36 patients with chronic hepatitis; 2 (40%), 4 (80%), and 4 (80%) of 5 with cirrhosis; 11 (39%), 17 (61%), and 22 (79%) of 28 with hepatocellular carcinoma; and 9 (18%), 39 (78%), and 40 (80%) of 50 volunteer blood donors, respectively. Of the interpretable 25 PCR products amplified with primers set A, 9 were classified as genotype 1a, 10 as genotype 1b, 4 as genotype 2, 1 as genotype 3, and 1 as genotype 4. Molecular evolutionary analysis did not suggest any particular strains of TTV that might be associated with chronic liver disease. The nucleotide sequences of the untranslated region on which PCR primers set B were designed were highly conserved, and the interpretable 22 PCR products amplified with primers set B were not clearly divisible into distinct genotypes. Our findings provided no evidence that TTV is a causative agent of chronic liver disease.

Chronic Disease↗

PubMed2000

Clinical usefulness of positron emission tomography with fluorine-18-fluorodeoxyglucose in the diagnosis of liver tumors.

We studied various liver tumors by positron emission tomography with fluorine-18 fluorodeoxyglucose (FDG-PET) to examine the diagnostic usefulness of this technique. We also examined the relation between findings on FDG-PET and the characteristics of hepatocellular carcinoma. FDG-PET was performed in 78 patients with liver tumors, including 53 with primary liver cancer [48 hepatocellular carcinomas (HCC) and 5 cholangiocellular carcinomas (CCC)], 20 with metastatic liver cancer, 2 with liver hemangioma, and 3 with focal nodular hyperplasia. For quantitative evaluation, a region of interest (ROI) was placed over the entire tumor region, at the level of the maximum diameter of the tumor. A background ROI was then placed over the non-tumor region of the liver. The average activity within each ROI was subsequently corrected for radioactive decay, and the standardized uptake value (SUV) was calculated by dividing the tissue activity by the injected dose of radioactivity per unit body weight. SUV ratio was expressed as the tumor-to-non-tumor ratio of the SUV. The median SUV was significantly lower in HCC than in metastatic live cancer or CCC, and the median SUV ratio was significantly lower in HCC than in metastatic liver cancer or CCC. The median SUV was not higher in multiple HCC than in single HCC, but the median SUV ratio was significantly higher in multiple HCC than in single HCC. The median SUV and the median SUV ratio were significantly higher in the presence of portal vein thrombosis than in the absence of such thrombosis. The Cancer of the Liver Italian Program score and the alpha-fetoprotein value correlated significantly with both the SUV and SUV ratio. These results suggest that FDG-PET is clinically useful not only for the differential diagnosis of liver tumors but also for evaluation of the clinical characteristics of HCC.

Adult↗

PubMed2000

Activation of monocytes and endothelial cells depends on the severity of surgical stress.

Surgical injury not only induces a systemic endocrine-metabolic response but also influences the function of the leukocytes and endothelial cells leading to various systemic responses. These responses appear to depend on the severity of surgical stress, which differs according to the surgical procedures. In this study, we investigated the response of monocytes and endothelial cells, and the development of systemic inflammatory response syndrome (SIRS) in relation to the severity of surgical stress. The postoperative clinical course was evaluated between patients undergoing an esophagectomy (ER group) and a distal gastrectomy (DG group). The tumor necrosis factor alpha (TNF-alpha) production of monocytes, the serum interleukin 6 (IL-6) levels, the CD11b expression on either monocytes or granulocytes, and the intercellular adhesion molecule-1 (ICAM-1) expression on human umbilical vein endothelial cells (HUVECs) stimulated with culture supernatants of monocytes were compared between the 2 groups. The development of SIRS was observed in all patients in the ER group, whereas no patients demonstrated SIRS in the DG group. The serum IL-6 levels, TNF-alpha production of monocytes, and CD11b intensity on monocytes or granulocytes in the ER group were higher than those in the DG group. In the ER group, the ICAM-1 intensity on HUVECs with monocytes immediately after operation significantly increased compared with before the operation. In conclusion, both the CD11b expression on monocytes and the TNF-alpha production of monocytes are considered to reflect the degree of surgical stress, and the activation of endothelial cells stimulated with these activated leukocytes may therefore lead to both tissue and organ injury.

Adenocarcinoma↗

PubMed2000

Clinicopathological characterization of prion: a novel marker of activated human hepatic stellate cells.

BACKGROUND/AIMS: We recently demonstrated prion as a new marker for hepatic stellate cell activation in rats. Here, we have examined prion expression in normal and diseased human livers. METHODS: Prion expression was examined at protein level by immunohistochemistry and at mRNA level by in situ hybridization. RESULTS: While normal livers were negative for prion, all liver specimens but one from patients with chronic liver disease were positively stained. In chronic hepatitis, prion protein expression was found not only in the sinusoidal lining cells within the lobules but also in mesenchymal cells in expanded portal tracts. In alcoholic liver disease, prion-positive cells were found mainly in the areas of alcoholic hepatitis. Immunoelectronmicroscopy revealed that prion-positive cells were activated stellate cells. In situ hybridization demonstrated that the distribution of prion mRNA is similar to that of prion protein. In chronic hepatitis, the number of prion-positive cells correlated with the grade of activity but not with the stage of fibrosis. In alcoholic liver disease, levels of prion protein expression were significantly increased in the presence of alcoholic hepatitis. CONCLUSION: Prion as a novel marker of activated stellate cells correlates well with disease activity in human chronic liver diseases.

Biomarkers↗

PubMed2000

Effects of magnesium and its mechanism on the incidence of reperfusion arrhythmias following severe ischemia in isolated rat hearts.

Magnesium sulfate (Mg) has been widely used for the treatment of ventricular arrhythmias (VF) in patients with coronary artery disease. However, the mechanisms of prevention on the incidence of VF have not been defined. The aim of study was to investigate the role of Mg in the prevention of VF and the mechanism of those effects. Series 1 studied antiarrhythmic effects on VF. Isolated rat hearts were perfused in the working heart mode with Krebs'-Henseleit bicarbonate buffer (KHB). Whole heart ischemia was induced by a one-way ball valve with 300 beats/min electrical pacing for 10 minutes followed by 20 minutes of aerobic reperfusion. After control perfusion, Mg was added from 5 minutes before ischemia and was continued to the end of ischemia (1.2 mM for the control group and 2.4, 3.6, 4.8, and 9.6 mM for the study animals) or during reperfusion (3.6 mM). Left ventricular pressure, aortic flow, and ECG were monitored. Series 2 studied the effect of Mg on [Ca2+]i. Hearts were perfused by the Langendorff mode and were loaded with 4 microM of Fura 2/AM as a [Ca2+]i indicator. Ca2+ was monitored using the ratio of Fura-2 fluorescence intensity at excitation wavelengths of 340 and 380 nm. The hearts were subjected to a 20 minutes of low-flow ischemia followed by 20 minutes of aerobic reperfusion. Then 3.6 mM Mg was added to the KHB medium during ischemia. The duration of VF was significantly suppressed in the 2.4, 3.6, and 4.8 mM/L Mg-added groups (472 +/- 173, 779 +/- 159, and 525 +/- 202 second, respectively) when compared with the control group (1200 seconds). Magnesium sulfate suppressed the fluorescence ratio of the diastolic Ca2+ level at the end of 20 minutes of ischemia from 40.5 +/- 3.6% to 9.0 +/- 1.0% (P < 0.05 vs. control hearts). These results suggested that Mg had a beneficial effect on VF and that the optimal Mg concentration was between 2.4 and 4.8 mM. The mechanism of the prevention of VF by Mg could be through the inhibition of [Ca2+]i retention during ischemia.

Animals↗

PubMed2000

The liver as a crucial organ in the first line of host defense: the roles of Kupffer cells, natural killer (NK) cells and NK1.1 Ag+ T cells in T helper 1 immune responses.

The liver remains a hematopoietic organ after birth and can produce all leukocyte lineages from resident hematopoietic stem cells. Hepatocytes produce acute phase proteins and complement in bacterial infections. Liver Kupffer cells are activated by various bacterial stimuli, including bacterial lipopolysaccharide (LPS) and bacterial superantigens, and produce interleukin (IL)-12. IL-12 and other monokines (IL- 18 etc.) produced by Kupffer cells activate liver natural killer (NK) cells and NK1.1 Ag+ T cells to produce interferon-gamma and thereby acquire cytotoxicity against tumors and microbe-infected cells. These liver leukocytes and the T helper 1 immune responses induced by them thus play a crucial role in the first line of defense against bacterial infections and hematogenous tumor metastases. However, if this defense system is inadequately activated, shock associated with multiple organ failure takes place. Activated liver NK1.1 Ag+ T cells and NK cells also cause hepatocyte injury. NK1.1 Ag+ T cells and another T-cell subset with an intermediate T-cell receptor, CD 122+CD8+ T cells, can develop independently of thymic epithelial cells. Liver NK cells and NK1.1 Ag+ T cells physiologically develop in situ from their precursors, presumably due to bacterial antigens brought from the intestine via the portal vein. NK cells activated by bacterial superantigens or LPS are also probably involved in the vascular endothelial injury in Kawasaki disease.

Animals↗

PubMed2000

Decreased anti-Saccharomyces cerevisiae antibody titer by mesalazine in patients with Crohn's disease.

BACKGROUND: Saccharomyces cerevisiae may contribute to the pathophysiology of Crohn's disease. We determined serum anti-Saccharomyces cerevisiae antibody (ASCA) levels in patients with inflammatory bowel disease. METHODS AND RESULTS: Immunoglobulin G (IgG) ASCA was measured by using an ELISA in serum samples from 19 patients with ulcerative colitis, 18 patients with Crohn's disease and 7 healthy controls. The ASCA level was significantly higher in patients with ulcerative colitis and patients with Crohn's disease than in controls, and was significantly higher in patients with Crohn's disease compared with patients with ulcerative colitis. Age, gender, disease activity, extent of disease and small bowel involvement each did not affect ASCA levels. The use of elemental or polymeric diet therapy for Crohn's disease and administration of corticosteroids to patients with inflammatory bowel disease also did not affect ASCA levels. The ASCA titer was significantly lower in patients with Crohn's disease taking mesalazine than in those not taking it, although, serum IgG levels did not differ between these two groups, which might imply a suppression of IgG production by mesalazine at the intestinal level. CONCLUSIONS: The finding of increased serum ASCA titers in patients with inflammatory bowel disease suggests that Saccharomyces cerevisiae may play a role in the pathophysiology of this condition.

Adult↗

PubMed2000

Ultrastructure of early phase hepatic metastasis of human colon carcinoma cells with special reference to desmosomal junctions with hepatocytes.

To demonstrate ultrastructural events in the early phase of hepatic metastasis of human colon carcinoma, we intrasplenically injected a highly metastasizable, human colon carcinoma cell line LM-H3 (1 x 10(6) cells) into nude mice, and electron microscopically investigated the hepatic metastasis. At 24 h, tumor cells adhered to the endothelial wall of terminal portal venules and periportal sinusoids. At 48-72 h, after extravasation, they deeply invaded the hepatic cell plate and the interstitial tissue of the portal tract, in which they underwent proliferation and made the metastatic foci. Tumor cells were linked with each other or with surrounding hepatocytes by desmosomes. Desmosomes were maintained during the mitosis. When invading tumor cells were exposed to the bile canaliculi, they generated microvilli on the surface. Microvilli were also formed at the luminal surface of intracytoplasmic inclusions. In the interstitial tissue of the portal tract, tumor cells were closely associated with fibroblasts. However, no junctional specializations were seen between them. The present study demonstrated that human colon carcinoma cell line LM-H3 formed desmosomes with hepatocytes soon after invasion of the hepatic cell plate, suggesting the regulatory role of an interaction with hepatocytes in the growth of metastatic foci within the liver parenchyma.

Animals↗

PubMed2000

Decrease of CD56(+)T cells and natural killer cells in cirrhotic livers with hepatitis C may be involved in their susceptibility to hepatocellular carcinoma.

CD56(+)T cells and CD56(+)natural killer (NK) cells are abundant in the human liver. The aim of this study was the further characterization of these cells in the liver with or without hepatitis C virus (HCV) infection. Liver mononuclear cells (MNC) were isolated from liver specimens obtained from the patients during abdominal surgery. In addition to a flow cytometric analysis, liver MNC and PBMC were cultured with the immobilized anti-CD3 Ab, IL-2, or a combination of IL-2 and IL-12 and their IFN-gamma production and the antitumor cytotoxicity were assessed. The liver MNC of HCV (-) patients contained 20% CD56(+)T cells whereas the same proportions decreased to 11% in chronic hepatitis livers and to 5% in cirrhotic livers. The proportion of NK cells also decreased in the cirrhotic livers. On the other hand, the populations of these cells in PBMC did not significantly differ among patient groups. The IFN-gamma production and the cytotoxicity against K562 cells, Raji cells, and a hepatocellular carcinoma, HuH-7 cells, greatly decreased in the cirrhotic liver MNC. In contrast, the cytotoxicity in PBMC did not significantly differ among the patient groups and was lower than that in the liver MNC of HCV (-) patients. CD56(+)T cells and NK cells but not regular T cells purified from liver MNC cultured with cytokines showed potent cytotoxicities against HuH-7 cells. These results suggest that a decreased number of CD56(+)T cells and NK cells in cirrhotic livers may be related to their susceptibility to hepatocellular carcinoma.

Aged↗

PubMed2000

Proteome analysis of rat hepatic stellate cells.

Proteome analysis was performed on cellular and secreted proteins of normal (quiescent) and activated rat hepatic stellate cells. The stellate cells were activated either in vitro by cultivating quiescent stellate cells for 9 days or in vivo by injecting rats with carbon tetrachloride for 8 weeks. A total of 43 proteins/polypeptides were identified, which altered their expression levels when the cells were activated in vivo and/or in vitro. Twenty-seven of them showed similar changes in vivo and in vitro, including up-regulated proteins such as calcyclin, calgizzarin, and galectin-1 as well as down-regulated proteins such as liver carboxylesterase 10 and serine protease inhibitor 3. Sixteen of them showed different expression levels between in vivo and in vitro activated stellate cells. These results were reproducibly obtained in 3 independent experiments. The up-regulation of calcyclin, calgizzarin, and galectin-1, as well as the down-regulation of liver carboxylesterase 10 were directly confirmed in fibrotic liver tissues. Northern blots confirmed up-regulation of the messenger RNAs (mRNAs) of calcyclin, calgizzarin, and galectin-1 in activated stellate cells, indicating that these changes were controlled at the mRNA level. In addition a list compiling over 150 stellate cell proteins is presented. The data presented here thus provide a significant new protein-level insight into the activation of hepatic stellate cells, a key event in liver fibrogenesis.

Animals↗

PubMed2000

Laparoscopic microwave coagulation therapy for hepatocellular carcinoma.

BACKGROUND AND STUDY AIMS: Several different effective forms of treatment are available, singly or in combination, for patients with hepatocellular carcinoma (HCC). These include surgical resection, transcatheter arterial embolization, percutaneous ethanol injection, and percutaneous microwave coagulation therapy. In this study, we carried out laparoscopic microwave coagulation therapy (LMCT), using laparoscopic microwave electrodes to treat HCC. PATIENTS AND METHODS: Under local anesthesia, 24 patients with HCCs located on or near the liver surface underwent LMCT under direct laparoscopic vision, with ultrasound guidance. LMCT was performed using microwave electrodes with tips ranging from 15-45 mm in length, and the effectiveness of the treatment was confirmed using contrast-enhanced computed tomography (CT) within two weeks of the LMCT procedure. RESULTS: The mean longest axis of the 26 HCC nodules in 24 patients was 20 mm, and that of the coagulated areas including the nodules was 40 mm, with additional therapy being required in two patients. Complete efficacy of the treatment was observed in 21 patients (87.5%), but local recurrences were seen in three of them one year after LMCT. The three-year survival rate was 92%, but the number of patients included in the study was small. Hemostasis was complete, but mild pneumothorax occurred in three patients. CONCLUSIONS: LMCT under local anesthesia is a minimally invasive and effective therapy when carried out on a single occasion to treat HCCs located near the liver surface, and it can be safely performed under direct visual guidance.

Aged↗

PubMed2000

Halothane attenuates the endothelial Ca2+ increase and vasorelaxation of vascular smooth muscle in the rat aorta.

Isolated spiral strips of rat thoracic aorta with endothelium were suspended for isometric tension recordings in a physiological salt solution. Endothelium-dependent vasorelaxation was elicited by carbachol 10(-6) and 10(-5) mol litre-1 during norepinephrine-induced contractions, and the effects of 1.5% and 3% halothane were evaluated with concomitant measurement of [Ca2+]i using fura-2-Ca2+ fluorescence. The effects of halothane on endothelium-dependent relaxation were compared with those of nitro G-L-arginine methyl ester 10(-4) mol litre-1 (L-NAME: an inhibitor of nitric oxide synthase). Carbachol reduced norepinephrine-induced contractions in a concentration-dependent manner, but augmented the norepinephrine-induced increase in [Ca2+]i in endothelium intact strips. In contrast, carbachol did not influence muscle tension or [Ca2+]i when the endothelium was completely denuded. Although 3% halothane and L-NAME 10(-4) mol litre-1 inhibited carbachol-induced vasorelaxation in a similar manner, halothane inhibited carbachol-induced increases in [Ca2+]i. These results indicate that halothane inhibited a carbachol-induced increase in [Ca2+]i in the endothelium, which subsequently attenuated the decrease in muscle tension.

Anesthetics, Inhalation↗

PubMed2000

In vivo and in vitro interactions between human colon carcinoma cells and hepatic stellate cells.

Stromal reaction is important for the growth of cancer both in primary and metastatic sites. To demonstrate this reaction during the hepatic metastasis of human colon carcinoma, we histologically investigated alterations to the distribution and phenotype of hepatic stellate cells (HSCs), the only mesenchymal cells in the liver parenchyma, using a nude mouse model. Intrasplenically injected colon carcinoma LM-H3 cells migrated into the space of Disse and underwent proliferation, in close association with hepatocytes and HSCs, at 2 days. At 14 days, HSCs were accumulated around the tumor mass and expressed alpha-smooth muscle actin, a marker for HSC activation. We next investigated in vitro the growth factors involved in the interactions between LM-H3 cells and HSCs. Conditioned medium of rat HSCs which underwent culture-induced activation contained platelet-derived growth factor (PDGF)-AB, hepatocyte growth factor (HGF) and transforming growth factor (TGF)-beta, and could augment LM-H3-cell proliferation and migration. Neutralizing antibodies against PDGF-AA and PDGF-BB and those against PDGF-BB and HGF inhibited proliferation and migration, respectively, of LM-H3 cells, whereas antibody against TGF-beta had no effect. LM-H3 cells expressed PDGF receptors-alpha and -beta and c-met. Conditioned medium of LM-H3 cells contained PDGF-AB, and could enhance HSC proliferation and migration. This augmenting effect was suppressed by treatment with anti-PDGF-AB antibody. The present study has demonstrated that bidirectional interactions involving PDGF and HGF take place in vitro between colon carcinoma cells and HSCs, raising the possibility that similar interactions might be involved in the stromal reaction during hepatic metastasis.

Adenocarcinoma↗