The active site cysteine of the proapoptotic protein glyceraldehyde-3-phosphate dehydrogenase is essential in oxidative stress-induced aggregation and cell death

Recent studies have revealed that the redox-sensitive glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), is involved in neuronal cell death that is triggered by oxidative stress. GAPDH is locally deposited in disulfide-bonded aggregates at lesion sites in certain neurodegenerative diseases. In this study, we investigated the molecular mechanism that underlies oxidative stress-induced aggregation of GAPDH and the relationship between structural abnormalities in GAPDH and cell death. Under nonreducing in vitro conditions, oxidants induced oligomerization and insoluble aggregation of GAPDH via the formation of intermolecular disulfide bonds. Because GAPDH has four cysteine residues, including the active site Cys(149), we prepared the cysteine-substituted mutants C149S, C153S, C244A, C281S, and C149S/C281S to identify which is responsible for disulfide-bonded aggregation. Whereas the aggregation levels of C281S were reduced compared with the wild-type enzyme, neither C149S nor C149S/C281S aggregated, suggesting that the active site cysteine plays an essential role. Oxidants also caused conformational changes in GAPDH concomitant with an increase in beta-sheet content; these abnormal conformations specifically led to amyloid-like fibril formation via disulfide bonds, including Cys(149). Additionally, continuous exposure of GAPDH-overexpressing HeLa cells to oxidants produced disulfide bonds in GAPDH leading to both detergent-insoluble and thioflavin-S-positive aggregates, which were associated with oxidative stress-induced cell death. Thus, oxidative stresses induce amyloid-like aggregation of GAPDH via aberrant disulfide bonds of the active site cysteine, and the formation of such abnormal aggregates promotes cell death.

A minor role for Ca2+ sensitization in sustained contraction through activation of muscarinic receptor in circular muscle of rat distal colon

We previously demonstrated that Ca(2+) sensitization has an essential role for carbachol-induced contraction in the longitudinal muscle of the rat distal colon. In the present study, we extended these studies to clarify the role of Ca(2+) sensitization in contraction induced by the activation of muscarinic receptors in the circular muscle of the rat distal colon. Carbachol induced a rapid phasic contraction followed by a sustained contraction that was significantly lower than the phasic and was superimposed with the rhythmic contractions. The extent of increase in intracellular Ca(2+) concentration that was measured simultaneously with tension recording was dissociated from the phasic contraction, whereas it exhibited to a similar extent as sustained contraction. In alpha-toxin-permeabilized preparations, Ca(2+) induced contraction comprising a rapid phasic and a subsequent low sustained component. After Ca(2+)-induced sustained contraction reached a constant level, guanosine triphosphate (GTP) addition resulted in the enhancement of contractile force in a concentration-dependent manner. Carbachol in the presence of GTP caused a further minimal increase in tension (Ca(2+) sensitization). Chelerythrine, a protein kinase C (PKC) inhibitor, inhibited carbachol-induced Ca(2+) sensitization but not GTP-induced Ca(2+) sensitization. In contrast, Y-27632, a Rho kinase inhibitor, inhibited GTP-induced Ca(2+) sensitization but not that induced by carbachol. Phorbol 12,13-dibutyrate, a PKC activator, increased the sustained contraction. These results suggest that the activation of muscarinic receptor with carbachol induces Ca(2+) sensitization via activation of PKC, but this action is minor in the circular muscle of the rat distal colon as a result of limited coupling between muscarinic receptors and Ca(2+) sensitization via the PKC pathway.

Orexin A affects ascending contraction depending on downstream cholinergic neurons and descending relaxation through independent pathways in mouse jejunum

The involvement of orexin in neural pathways for peristalsis was examined in mouse jejunal segments. Localized distension of the segments using a small balloon resulted in ascending contraction and descending relaxation. Ascending contraction was abolished by atropine and tetrodotoxin. Desensitization to orexin A (OXA) and SB-334867-A, an orexin-1 receptor antagonist, significantly inhibited ascending contraction. Hexamethonium also produced a significant inhibition. Exogenous administration of either OXA or nicotine induced a transient contraction that was completely inhibited by atropine and tetrodotoxin. The OXA-induced contraction was significantly inhibited by hexamethonium and SB-334867-A, whereas the nicotine-induced contraction was not inhibited by SB-334867-A. Descending relaxation was either partially or completely inhibited by l-nitroarginine and tetrodotoxin, respectively. Both SB-334867-A and hexamethonium partially inhibited descending relaxation. A combination of SB-334867-A and hexamethonium had an additive inhibitory effect on descending relaxation. Exogenous OXA, in the presence of atropine, induced a relaxation that was significantly inhibited by both l-nitroarginine and SB-334867-A, but not by hexamethonium. Nicotine in the presence of atropine relaxed the jejunal segment. SB-334867-A, unlike hexamethonium, did not affect nicotine-induced relaxation. These results suggest that OXA plays an important role in the ascending and descending neural reflexes in the mouse jejunum.

Inhibitory effects of alendronate on cholinergic responses in rat lower esophageal sphincter

Alendronate is a potent inhibitor of osteoclast-mediated bone resorption, but its use results in serious esophageal damage. In order to clarify the latter, we examined the effects of alendronate on electrical field stimulation-induced responses in the rat lower esophageal sphincter. Electrical field stimulation induced atropine-sensitive contraction. Alendronate inhibited electrical field stimulation-induced contraction in a concentration-dependent manner. In the presence of N(G)-nitro-L-arginine (L-nitroarginine), electrical field stimulation elicited a strong cholinergic contraction. This contraction was also inhibited by alendronate, to a similar extent as that seen in the absence of L-nitroarginine. In lower esophageal sphincter contracted by prostaglandin F(2alpha) and treated with atropine, electrical field stimulation induced L-nitroarginine-sensitive relaxation. Alendronate did not affect relaxation. These results suggest that alendronate decreases the tone of lower esophageal sphincter by inhibiting cholinergic nervous activity.

Plasma level of a 5-fluorouracil metabolite, fluoro-beta-alanine correlates with dihydropyrimidine dehydrogenase activity of peripheral blood mononuclear cells in 5-fluorouracil treated patients

5-fluorouracil (5-FU) is mostly metabolized after administration, and the metabolizing enzyme, dihydropyrimidine dehydrogenase (DPD), seems to be the rate-limiting factor. However, there are few reports on the final metabolite, fluoro-beta-alanine (FBAL). We report here the results of determination of the FBAL level in 5-FU treated patients and the correlation between the FBAL level and the DPD activity in peripheral blood mononuclear cells (PBMCs). Blood samples were collected from 20 patients, who had received continuous intravenous infusion (CIV) of 5-FU (320 mg/m2/24 hr) after resection of colorectal cancer, and the FBAL level was determined by high performance liquid chromatography (HPLC), after derivatizing into o-phthalaldehyde (OPA) and detecting fluorescence. DPD activity was measured in cytosol prepared from PBMCs using HPLC radioassay. The average FBAL plasma level during CIV of 5-FU was 911.0 ng/ml (521.0 to approximately 1834.6 ng/ml) and that of DPD activity in PBMCs was 282.6 pmol/min/mg-protein (145.0 to approximately 568.0 pmol/min/mg-protein). There was a significant correlation between the FBAL level and the DPD activity (r=0.805, p<0.0001). FBAL level in plasma may be useful in predicting the DPD activity in PBMCs, however, further studies are required considering the small number of cases in this study.

Involvement of M(2) muscarinic receptors in relaxant response of circular muscle of mouse gastric antrum

Our previous study showed that atropine significantly inhibited the sustained relaxation induced by electrical field stimulation (EFS) in the circular muscle strips prepared from the mouse antrum, and that pituitary adenylate cyclase activating peptide (PACAP) partially mediated the sustained relaxation. The muscarinic receptor subtype associated with the sustained relaxation was examined in the present study by using each muscarinic receptor subtype of knockout (KO) mice. EFS-induced sustained relaxation in the antrum prepared from M(2) receptor KO mice was significantly less than that of wild-type mice. Atropine failed to inhibit this relaxation. On the other hand, similar sustained relaxation and inhibitory effects of atropine to those of wild-type mice were observed in M(1), M(3) and M(4) receptor KO mice. Exogenously added PACAP-27 relaxed the antral strips of wild-type and M(2) receptor KO mice to a similar extent. Immunohistochemical study revealed that M(2) receptor immunoreactivity was localized with PACAP-immunoreactivity in enteric neurons within the antrum of wild-type mice. In contrast, atropine did not affect the EFS-induced sustained relaxation in the gastric fundus. These results suggest that M(2) receptors modulate the sustained relaxation, probably through the regulation of PACAP release, in the mouse antrum.

Roles of PACAP and PHI as inhibitory neurotransmitters in the circular muscle of mouse antrum

Mediators of neurogenic responses of the gastric antrum were studied in wild-type and pituitary adenylate cyclase-activating polypeptide (PACAP) -knockout (KO) mice. Electrical field stimulation (EFS) to the circular muscle strips of the wild-type mouse antrum induced a triphasic response; rapid transient relaxation and contraction, and sustained relaxation that was prolonged for an extended period after the end of EFS. The transient relaxation and contraction were completely inhibited by L-nitroarginine and atropine, respectively. The sustained relaxation was significantly inhibited by a PACAP receptor antagonist, PACAP(6-38). The antral strips prepared from PACAP-KO mice unexpectedly exhibited a tri-phasic response. However, the sustained relaxation was decreased to about one-half of that observed in wild-type mice. PACAP(6-38) inhibited EFS-induced sustained relaxation (33.5% of control) in PACAP-KO mice. Anti-peptide histidine isoleucine (PHI) serum partially (the 30% inhibition) or significantly (the 60% inhibition) inhibited the sustained relaxations in the wild-type and PACAP-KO mice, respectively. The immunoreactivities to the anti-PACAP and anti-PHI serums were found in myenteric ganglia of the mouse antrum. These results suggest that nitric oxide and acetylcholine mediate the transient relaxation and contraction, respectively, and that PACAP and PHI separately mediate the sustained relaxation in the antrum of the mouse stomach.

PACAP- and PHI-mediated sustained relaxation in circular muscle of gastric fundus: findings obtained in PACAP knockout mice

Mediators of neurogenic responses of the gastric fundus were studied in wild type and pituitary adenylate cyclase activating peptide (PACAP) knockout mice. Electrical field stimulation (EFS) to the circular muscle strips of the wild type mouse fundus induced a tri-phasic response, rapid transient contraction and relaxation, and sustained relaxation that was prolonged for an extended period after the end of EFS. The transient relaxation and contraction were completely inhibited by N(G)-nitro-L-arginine and atropine, respectively. The sustained relaxation was completely inhibited by a PACAP receptors antagonist, PACAP(6-38). The strips prepared from PACAP knockout mice exhibited a large contraction without rapid relaxation and unexpectedly, a sustained relaxation. However, the sustained relaxation was decreased to about a half of that observed in wild type mice. Anti-peptide histidine isoleucine (PHI) serum abolished the sustained relaxation in the knockout mice. The serum partially inhibited the sustained relaxation in wild type mice and PACAP(6-38) abolished the relaxation that remained after the antiserum-treatment. PHI relaxed the strips prepared from wild type mice. The relaxation was completely inhibited by PACAP(6-38). It was concluded that PACAP and PHI separately mediate the sustained relaxation in the mouse gastric fundus, and that nitric oxide and ACh mediate transient relaxation and contraction, respectively.

Examination of the role of cholinergic myenteric neurons with the impairment of neural reflexes in the ileum of c-kit mutant mice

Our previous study showed that impairment of ascending and descending neural reflexes in the ileum of the c-kit mutant, W/W(V), mice is due to a loss of interstitial cells of Cajal present at the myenteric plexus region (ICC-MY) in the mutant. In the present study, cholinergic interneurons were thought to be involved in these pathways, since hexamethonium, an antagonist of the nicotinic ACh receptor, significantly inhibited both neural reflexes in wild type mice. Therefore, we examined whether the loss of ICC-MY affects cholinergic interneurons involved in these pathways. Immunohistochemistry with anti-choline acetyltransferase revealed that there was no difference in the numbers of immunopositive cells in the myenteric plexus region between the wild type and mutant mice. In addition, there was no difference in the extent of spontaneous and EFS-evoked ACh release from longitudinal muscle with myenteric plexus preparations between the wild type and mutant mice. Exogenously added nicotine induced contraction or relaxation of ileal circular muscle in the absence or presence of atropine, respectively, to a similar extent in both the wild type and mutant mice. These results suggest that loss of ICC-MY resulted in an impairment of the ascending and descending reflex pathways at the step before activation of cholinergic interneurons.

Ascending contraction and descending relaxation in the distal colon of mice lacking interstitial cells of Cajal

Recently an essential role of interstitial cells of Cajal (ICC) within myenteric plexus (ICC-MY) was suggested in ascending contraction and descending relaxation in the mouse ileum. The role of ICC in these neural reflexes was examined in the distal colonic segments prepared from the wild type and c-kit mutant, W/W(V) mice, in the present study. Localized distension of the segments from the wild type mice by using a small balloon resulted in ascending contraction and descending relaxation. In the segments from the mutant mice, localized distension also induced these neural reflexes similar to those observed in the wild type mice. Immunohistochemical examination demonstrated that ICC-MY and ICC present in muscle layers (ICC-IM) were severely disrupted in the mutant mouse, but only ICC, present within submucosal plexus (ICC-SMP), remained unchanged. In the small strips with ICC-SMP absent prepared from the mutant mouse, electrical field stimulation induced contraction or relaxation in the absence or presence of atropine, respectively. It was suggested that ICC have no important role in the ascending and descending neural reflexes in the mouse distal colon, this is in direct contrast to the role of ICC-MY in the ileum.

Metastases-related genes in the classification of liver and peritoneal metastasis in human gastric cancer

INTRODUCTION

With the aim of identifying metastases-related genes in gastric cancer, we performed a broad analysis of differential gene expression between low-metastatic parental cell lines and established highly metastatic sublines.

MATERIALS AND METHODS

We established novel cell lines, AZ-H5c, NUGC-3H5, and TMK-1H7, with a high potential of liver metastasis, and AZ-P7a, NUGC-3P4T, and TMK-1P4a, with a high potential of peritoneal metastasis. These cell lines were derived from low-metastatic parental AZ-521, NUGC-3, and TMK-1 cell lines, respectively. Furthermore, to investigate different levels of gene expression implicated in metastatic potentials in gastric cancer, we investigated approximately 2000 expressed genes in each cell line using a DNA microarray.

RESULTS

Varieties of genes were up-regulated or down-regulated in highly metastatic liver and peritoneal cell lines. Fifty-eight genes, including the transferrin receptor, ras-related rho, and osteopontin, and 22 genes, including apolipoprotein E and inhibin A-submit, were up-regulated and down-regulated in two or three liver metastatic sublines. On the other hand, 19 genes, the transferrin receptor, c-fos, and RANTES, and 26 genes, including MAC25, PISSLRE, and RNA polymerase, were up-regulated and down-regulated in two or three peritoneal metastatic sublines.

CONCLUSION

How gene expression is implicated in gastric cancer metastasis has never been thoroughly explained, and further studies are necessary to understand the involvement of genes in cancer metastasis more thoroughly. We hope that our highly metastatic liver and peritoneal experimental models are helpful for further study and gene therapy of human gastric cancer.

Roles of M2 and M4 Muscarinic Receptors in Regulating Acetylcholine Release From Myenteric Neurons of Mouse Ileum

We investigated the subtype of presynaptic muscarinic receptors associated with inhibition of acetylcholine (ACh) release in the mouse small intestine. We measured endogenous ACh released from longitudinal muscle with myenteric plexus (LMMP) preparations obtained from M1–M5 receptor knockout (KO) mice. Electrical field stimulation (EFS) increased ACh release in all LMMP preparations obtained from M1–M5 receptor single KO mice. The amounts of ACh released in all preparations were equal to that in the wild-type mice. Atropine further increased EFS-induced ACh release in the wild-type mice. Unexpectedly, atropine also increased, to a similar extent, EFS-induced ACh release to the wild-type mice in all M1–M5 receptor single KO mice. In M2 and M4 receptor double KO mice, the amount of EFS-induced ACh release was equivalent to an atropine-evoked level in the wild-type mouse, and further addition of atropine had no effect. M2 receptor immunoreactivity was located in both smooth muscle cells and enteric neurons. M4 receptor immunoreactivity was located in the enteric neurons, being in co-localization with M2 receptor immunoreactivity. These results indicate that both M2 and M4 receptors mediate the muscarinic autoinhibition in ACh release in the LMMP preparation of the mouse ileum, and loss of one of these subtypes can be compensated functionally by a receptor that remained. M1, M3, and M5 receptors do not seem to be involved in this mechanism.

[Pulmonary metastasis from colorectal cancer with hepatic metastasis]

We have investigated cases where pulmonary metastasis from colorectal cancer was resected during the last 15 years, comparing a group with liver metastasis [LM (+)] to a group without liver metastasis [LM (-)]. The following are the characteristics of the LM (+) versus LM (-) groups. Gender: male 6, female 5 versus male 9, female 11, age: 61.4+/-11.4 versus 63.9+/-9.4 years, number of lung metastasis: 1.42 versus 1.29, duration of primary-lung metastasis: 1.59+/-1.02 versus 2.55+/-1.46 years, preoperative CEA: 69.3+/-71.1 versus 8.64+/-5.63 ng/ml, ratio of bilateral lung metastasis: 23.0 versus 4.8%, more than 1 ratio of pulmonary metastasis: 38 versus 19%, complete resection ratio of pulmonary metastasis: 84.6 versus 100%, ratio of thoracoscopic surgery: 69.2 versus 66.7%, and 2-year survival ratio: 63 versus 78%. There were no statistically significant differences in these values between the LM (+) and LM (-) group. A larger number of cases and follow-up duration will be required in the future; we think that the resection of pulmonary metastasis from colorectal cancer with liver metastasis can be supported for the present.

Participation of ATP in nonadrenergic, noncholinergic relaxation of longitudinal muscle of wistar rat jejunum

A role of ATP in nonadrenergic, noncholinergic (NANC) relaxations was examined in the Wistar rat jejunum. Electrical field stimulation (EFS) induced NANC relaxation of longitudinal muscle of the jejunal segments in a frequency-dependent manner. A purinoceptor antagonist, adenosine 3'-phosphate 5'-phosphosulfate (A3P5PS, 100 muM) inhibited the relaxation: relaxations induced by EFS at lower or higher frequencies were either completely or partially inhibited, respectively. After the jejunal segments had been desensitized to ATP, the relaxations were decreased to the same extent as those inhibited by A3P5PS. An inhibitor of small conductance Ca(2+)-activated K(+) channels (SK channels), apamin (100 nM), completely inhibited EFS-induced relaxations. Treatment of the segments with an inhibitor of sarcoplasmic reticulum Ca(2+)-ATPase, thapsigargin (1 muM), significantly inhibited the relaxations. The exogenous ATP-induced relaxation of longitudinal muscle occurred with a concomitant decrease in intracellular Ca(2+) levels. Apamin and thapsigargin abolished these ATP-induced responses. A3P5PS significantly inhibited the inhibitory junction potentials which were induced in the longitudinal muscle cells. In addition, apamin significantly inhibited the hyperpolarization that was induced by exogenous ATP in the cells. These findings in the Wistar rat jejunum suggest that ATP participates in the NANC relaxation via activation of SK channels induced by Ca(2+) ions that are released from the thapsigargin-sensitive store site.

Essential role of the interstitial cells of Cajal in nitric oxide-mediated relaxation of longitudinal muscle of the mouse ileum

The role of interstitial cells of Cajal (ICC) in electrical field stimulation (EFS)-induced neurogenic responses in ileum was studied by using the ICC-deficient mutant (SLC-W/W(V)) mouse and its wild type. In the immunohistochemical study with anti-c-Kit antibody, ICC was observed in the myenteric plexus (MY) and deep muscular plexus (DMP) region in the wild type. In the mutant, ICC-MY were lost, only ICC-DMP were present. EFS induced a rapid contraction of the ileal segments from the wild type mouse in the direction of longitudinal muscle. In the mutant mouse, onset of contraction was delayed and its rate was slowed. EFS induced nonadrenergic, noncholinergic (NANC) relaxation in the presence of atropine and guanethidine in the wild type. A nitric oxide synthase inhibitor inhibited the relaxation and L-arginine reversed it. In the mutant, EFS did not induce NANC relaxation. There was no difference between the responsiveness of the segments from wild type and mutant mice to exogenously added acetylcholine or Nor-1. Taking into account the selective loss of ICC-MY in the mutant mice, it seems likely that ICC-MY have an essential role in inducing nitric oxide-mediated relaxation of longitudinal muscle of the mouse ileum and that ICC-MY partly participate in EFS-induced contraction.

Role of the interstitial cells distributed in the myenteric plexus in neural reflexes in the mouse ileum

We examined the role of interstitial cells of Cajal (ICC) in the ascending and descending neural reflexes in the ileal segments prepared from wild type mice and c-kit mutant W/WV mice. Localized distension of the ileal segments from wild type mice with a small balloon caused contraction or relaxation of the circular muscle on the oral or anal side of the distended region, respectively. However, these intestinal reflexes were not induced in the ileal segments from the mutant mice. In the small strips that include the step of the pathways from efferent motor neurons to smooth muscle cells, nerve stimulation induced contraction of circular muscle in the absence of atropine and relaxation in the presence of atropine. The extent of nerve stimulation-induced contractions and relaxations of the ileal circular muscle were similar in wild type and W/WV mice. The responsiveness of ileal circular muscle to exogenously added acetylcholine and Nor-1, a nitric oxide donor, was also unaffected in the mutant ileum. Since previous immunohistochemical study had revealed selective loss of ICC within the myenteric plexus (ICC-MY) in the mutant ileum, it was concluded that ICC-MY have an essential role in ascending and descending neural pathways in the mouse ileum.

Profiling analysis of differential gene expression between hematogenous and peritoneal metastatic sublines of human pancreatic cancer using a DNA chip

We established the novel sublines HPC-1H5, HPC-3H4, HPC-4H4, and Panc-1H5, which have a high potential of liver metastasis, and HPC-1P5a, HPC-3P4a, HPC-4P4a, and Panc-1P5a, which have a high potential of peritoneal dissemination, derived from low metastatic HPC-1, HPC-3, HPC-4, and Panc-1cell lines, respectively. To clarify the molecular mechanisms of cancer metastasis and of the different levels of gene expression in a variety of metastatic potentials in pancreatic cancer, we performed a broad analysis of differential gene expression analysis between parental cell lines and metastatic sublines. In comparison with the parental cell lines, 65 and 36 genes were overexpressed and underexpressed in highly liver-metastatic sublines. On the other hand, 43 and 45 genes were overexpressed and underexpressed in highly peritoneal-metastatic sublines. uPAR and Serin protease were overexpressed, and E2A and IGF1R were underexpressed in both metastatic sublines. Hierarchical clustering analysis revealed 22 genes classifying liver, peritoneal metastatic sublines and low-metastatic parental cell lines. These genes might be targeted genes separating those two major metastatic forms after surgery. A greater number of cell line samples and more genes will have to be utilized in future studies in order to understand the involvement of genes in cancer metastasis more thoroughly. However, these results will help to clarify the molecular mechanisms of pancreatic cancer metastasis.

Dependence of Ca2+-induced contraction on ATP in alpha-toxin-permeabilized preparations of rat femoral artery

Effects of various concentrations of ATP on Ca(2+)-induced contraction were studied in alpha-toxin-permeabilized preparations obtained from the rat femoral artery. The contractile magnitude was highest in the presence of 1 mM ATP and decreased with both increasing and decreasing the concentration, suggesting the presence of an optimum ATP concentration in inducing contraction. The magnitude of the contractions in various concentrations of ATP correlated with the extent of the phosphorylated myosin light chain (MLC). The rate of contractions in the presence of 1 mM ATP under an inhibition of MLC phosphatase was faster than in the presence of 4 mM ATP, suggesting that the increased phosphorylation of MLC at 1 mM ATP results from an increased activity of MLC kinase. On the other hand, MLC phosphatase activity appeared unchanged, because the rates of relaxations under the inhibition of MLC kinase were not different in the presence of either 1 or 4 mM ATP. The high sensitivity to 1 mM ATP was absent in the preparations that were permeabilized with beta-escin or Triton X-100, suggesting the existence of an intracellular factor required for the increased activity of MLC kinase to ATP in the alpha-toxin-permeabilized preparations of the rat femoral artery.

Mechanisms involved in carbachol-induced Ca(2+) sensitization of contractile elements in rat proximal and distal colon

1. Mechanisms involved in Ca(2+) sensitization of contractile elements induced by the activation of muscarinic receptors in membrane-permeabilized preparations of the rat proximal and distal colon were studied. 2. In alpha-toxin-permeabilized preparations from the rat proximal and distal colon, Ca(2+) induced a rapid phasic and subsequent tonic component. After Ca(2+)-induced contraction reached a plateau, guanosine 5'-triphosphate (GTP) and carbachol (CCh) in the presence of GTP further contracted preparations of both the proximal and distal colon (Ca(2+) sensitization). Y-27632, a rho-kinase inhibitor, inhibited GTP plus CCh-induced Ca(2+) sensitization more significantly in the proximal colon than in the distal colon. 3. Y-27632 at 10 microm had no effect on Ca(2+)-induced contraction or slightly inhibited phorbol-12,13-dibutyrate-induced Ca(2+) sensitization in either proximal or distal colon. Chelerythrine, a protein kinase C inhibitor, inhibited GTP plus CCh-induced Ca(2+) sensitization in the distal colon, but not in the proximal colon. The component of Ca(2+) sensitization that persisted after the chelerythrine treatment was completely inhibited by Y-27632. 4. In beta-escin-permeabilized preparations of the proximal colon, C3 exoenzyme completely inhibited GTP plus CCh-induced Ca(2+) sensitization, but PKC(19-31) did not. In the distal colon, C3 exoenzyme abolished GTP-induced Ca(2+) sensitization. It inhibited CCh-induced sensitization by 50 % and the remaining component was inhibited by PKC(19-31). 5. These results suggest that both protein kinase C and rho pathways in parallel mediate the Ca(2+) sensitization coupled to activation of muscarinic receptors in the rat distal colon, whereas the rho pathway alone mediates this action in the proximal colon.

Changes in mechanism of PACAP-induced relaxation in longitudinal muscle of the distal colon of Wistar rats with age

Mechanisms of relaxation of longitudinal muscle of the distal colon induced by exogenously added pituitary adenylate cyclase activating peptide (PACAP) were studied in 2- to 30-week-old Wistar rats. Exogenous PACAP induced very significant relaxation of the longitudinal muscle in 2-week-old rats, but this effect decreased significantly with age. The cyclic AMP-cyclic AMP-dependent protein kinase (PKA) pathway and the tyrosine kinase-small conductance Ca2+-activated K+ channel (SK channel) pathway were found to be involved in the mechanism of PACAP-induced relaxation. In 2-week-old rats, PACAP-induced relaxation was significantly inhibited by tetrodotoxin (TTX). Since relaxation was also significantly inhibited by NG-nitro-L-arginine (N5-nitro-amidino-L-2,5-diamino-pentanoic acid: L-NOARG), the neurogenic effect of PACAP seems to be mediated mainly through nitric oxide neurons. In 8-week-old rats, L-NOARG and TTX had little effect on PACAP-induced relaxation, suggesting that the relaxant effect in 8-week-old rats is a direct action on longitudinal smooth muscle cells. Changes in the mechanisms of PACAP-induced relaxation with age were examined in the distal colon in relation to changes in the neurogenic and the direct effects of PACAP. The neurogenic effect in the exogenous PACAP-induced relaxation of the longitudinal muscle of the Wistar rat distal colon is dominant in tissue isolated from 2-week-old and lost in tissue isolated from 8-week-old rats.

[Roles of interstitial cells of Cajal in regulation of motility of the mouse intestine]

The role of interstitial cells of Cajal (ICC) in contractile activity of the gastrointestinal tract has been intensely studied. Among ICC present within various regions of the gastrointestinal tissue, ICC within the myenteric plexus (ICC-MY) and within the submuscular plexus (ICC-SMP) are regarded as the pacemaker. Action potentials initiated in ICC were suggested to propagate to adjacent smooth muscle cells and to induce the spontaneous activity. It was suggested that ACh-mediated contraction and nitric oxide-mediated relaxation were induced after these neuronal signals were transmitted to ICC and then to smooth muscle via the gap junction. This suggestion was based on the findings mainly in the esophagus, stomach, and small intestine by using ICC-deficient mice (W/W(V) and Sl/Sl(d)). In our studies, ICC-MY were shown to be closely associated with neuron-mediated contractile and relaxant responses and to be associated with neural reflexes for peristalsis, since ascending and descending reflexes were not seen in W/W(V) mice. In the distal colon of W/W(V) mice, in which ICC-MY and -IM were lost, these neural responses remained unchanged. It seems likely that ICC-MY and ICC-IM do not have any role in inducing these responses in the distal colon. It is concluded that the extent of association of ICC with the motility and the manner of the association vary from region to region in the gastrointestinal tract.

Origin of ATP for Ca2+-induced contraction in the guinea-pig femoral artery

Previously, we have described differences between the rat proximal colon and femoral artery with respect to the role of ATP newly synthesized by creatine kinase. In the present study the role of newly synthesized ATP was studied in the guinea-pig femoral artery to examine species differences. In the alpha-toxin-permeabilized preparation of the guinea-pig femoral artery, the rapid Ca(2+)-induced contraction was suppressed when creatine kinase activity was inhibited. The contraction was restored completely by treatment with NaN(3), an inhibitor of ecto-ATPase, the enzyme that breaks down exogenous ATP. Thus, ATP newly synthesized by creatine kinase may have no role in contraction of the guinea-pig femoral artery. This is in marked contrast to the rat femoral artery, in which Ca(2+)-induced contractions are almost completely inhibited by inhibition of creatine kinase activity but only partly restored by NaN(3). To characterize the difference between the guinea-pig and rat tissue, the origin of ATP required for contraction was determined in intact preparations. Monoiodoacetic acid, an inhibitor of glycolysis, inhibited the high K(+)-induced contraction in the guinea-pig femoral artery more potently than in the rat tissue. In contrast, an inhibitor of mitochondrial respiration, carbonylcyanide p-(trifluoromethoxy)phenylhydrazone (FCCP), inhibited contraction in femoral arteries from rats, but not from guinea-pigs. These results suggest that contraction in the rat femoral artery is dependent largely on oxidative phosphorylation, while contraction in the guinea-pig tissue is dependent only on glycolysis. Because oxidative phosphorylation generates ATP and phosphocreatine, while glycolysis generates only ATP, the strong dependence of the contraction of the rat femoral artery on the oxidative phosphorylation is consistent with its dependence on ATP newly synthesized by creatine kinase from ADP and phosphocreatine, as previously shown. Thus, it is proposed that ATP, newly synthesized by creatine kinase, in addition to ATP generated by oxidative phosphorylation, is utilized for contraction in the rat femoral artery, while glycolysis produces sufficient ATP for contraction in the guinea-pig femoral artery.

Metastatic-associated biological properties and differential gene expression profiles in established highly liver and peritoneal metastatic cell lines of human pancreatic cancer

To elucidate metastasis mechanisms, we established a Panc-1H5 subline with a highly liver metastatic cell line and a Panc-1P4a with a highly peritoneal metastatic cell line, which were sequentially selected from the parental pancreatic cancer cell line Panc-1. Using these three cell lines, we investigated several biological properties and mRNA levels of differentially-expressed genes involved in cancer metastasis with a cDNA macroarray. The tumorigenicity, motile activity, adhesive activity and cytokine production of metastatic sublines were higher than those of parental Panc-1 cells. Particularly, in Panc-1H5 cells, adhesive activity to the extracellular matrix and angiogenetic factors increased, whereas in Panc-1P4a cells, motile activity was extremely enhanced compared with Panc-1 cells. Histopathological findings for the three cell lines were the same. In cDNA macroarray analysis of Panc-1H5 cells, 11 genes were up-regulated and 20 genes were down-regulated compared with parental Panc-1 cells. In Panc-1P4a cells, 7 genes were up-regulated and 13 genes were down-regulated compared with parental Panc-1 cells. This study provides a demonstration of global gene expression analysis of pancreatic cancer cells with liver and peritoneal metastasis and these results provide new insight into the study of human pancreatic cancer metastasis.

Expression of the small conductance Ca2+-activated K+ channel, SK3, in the olfactory ensheathing glial cells of rat brain

Olfactory sensory neurons are wrapped by ensheathing glial cells in the olfactory nerve layer (ONL). Neither functional roles nor electrical properties of ensheathing glial cells have been, as yet, fully clarified. Four subunits (SK1-4) of small conductance Ca2+-activated K+ (SK) channels have been cloned. In the present study, immunohistochemical analyses showed that SK3 channels are expressed in ensheathing glial cells in the rat olfactory bulb, in addition to neuronal cells in other regions. Western blotting analysis demonstrated that SK3 was predominantly expressed in the olfactory bulb, thalamus, moderately in the hippocampus and cerebellum and modestly in the cerebral cortex of the rat brain. SK3 immunoreactivity was detected in the ONL of the olfactory bulb, neural cell body and fibers of the substantia nigra and hypothalamus. SK3 immunoreactivity was quite intense in the outer (superficial) part of the ONL. SK3-immunoreactive structures were overlapped with glial fibrillary acidic protein (GFAP), but not with vimentin, markers for glial cells and olfactory sensory axons, respectively. Immunoelectron microscopy showed that SK3 immunoreactivity was localized in thin processes that enfolded fascicles of immunonegative olfactory nerve axons. These results indicate that SK3 is expressed specifically in the olfactory ensheathing glial cells in olfactory regions.

Essential role of ATP synthesized by creatine kinase in contraction of alpha-toxin permeabilized preparations of tonic type smooth muscle

The role of ATP newly synthesized from ADP and phosphocreatine (PC) by creatine kinase (CK) in the contraction of tonic type smooth muscle, rat femoral artery was studied, since its necessity for phasic type smooth muscle was previously shown. In alpha-toxin-permeabilized preparations obtained from rat femoral artery, Ca(2+) induced a tonic type contraction in the presence of ATP and PC. Omission of PC inhibited significantly the contraction. Treatment of the preparations with 2,4-dinitrofluorobenzene, an inhibitor of CK, also inhibited the contraction. In the presence of ADP and PC, Ca(2+) also induced the contraction to a level comparable to that in the presence of ATP and PC. The extent of phosphorylated myosin light chain was fairly consistent with that of Ca(2+)-induced contraction under all experimental conditions planned above. These results suggest that ATP newly synthesized by CK essentially participates in the whole of the contraction in tonic type smooth muscle, although it participates only in a rapid phasic contraction in phasic type muscle as previously shown.

Differential gene expression screening between parental and highly metastatic pancreatic cancer variants using a DNA microarray

To clarify the difference in genes expressed in hematogenous metastasis and peritoneal dissemination, a broad analysis of differential gene expression analysis between parental cell lines and established metastatic sublines was performed. Using an oligonucleotide array (Gene Chip, Affymetrix), approximately 2,000 genes involved in cancer were analyzed for each of the cell lines. HPC-4H4 (highly metastatic lines to the liver) compared with HPC-4 (low metastatic parental lines), in which 20 overexpressed genes and 5 underexpressed genes were recognized. HPC-4P4a (highly metastatic to the peritoneum) compared with HPC-4, in which 12 overexpressed genes and 15 underexpressed genes were also recognized. Analysis of HPC-4H4 and HPC-4P4a showed comparative up-regulation of 20 genes and down-regulation of 13 in the former, HPC-4H4. Further studies are needed to validate our hypothesis that some of the resulting differentially expressed genes might be implicated in the development of metastasis in pancreatic cancer. In conclusion, this genome-wide expression analysis will help to clarify the molecular mechanisms of cancer metastasis and of the different levels of gene expression in a variety of metastatic potentials in pancreatic cancer.

Expression analysis of vascular endothelial growth factors and their relationships to lymph node metastasis in human colorectal cancer

This study was undertaken to determine whether expressions of the vascular endothelial growth factor (VEGF) family (VEGF-A, VEGF-B, VEGF-C, and VEGF-D) are correlated with clinicopathological parameters, with particular reference to lymph node metastasis in colorectal cancer. Total RNA was isolated from 82 surgical specimens of colorectal cancer and matched to normal mucosa with (n = 41) or without (n = 41) lymph node metastasis. The mRNA expression of each VEGF family member was quantified by real-time quantitative (RTQ) RT-PCR assay. VEGF-B and VEGF-C mRNA were significantly higher both in the tumors with lymph node metastasis (p = 0.027 and p = 0.024, respectively) and in tumors with lymphatic invasion (p = 0.042 and p = 0.005, respectively). In contrast, VEGF-D mRNA was down-regulated in tumors with lymphatic involvement (p = 0.047). Among the other clinicopathological factors, we noted that VEGF-A mRNA was higher in tumors with liver metastasis than in those without (p = 0.018) and was higher in tumors with venous invasion than in those without (p = 0.007). The results of this study demonstrate that high levels of VEGF-B, C and low levels of VEGF-D mRNA expression are associated with lymph node metastasis and lymphatic involvement. These results suggest that a balance among VEGF-B, VEGF-C, and VEGF-D might contribute to the lymphangiogenic process and metastasis in colorectal cancer.

Localization of Ca2+-activated K+ channel, SK3, in fibroblast-like cells forming gap junctions with smooth muscle cells in the mouse small intestine

In the present study, we examined the expression and the localization of apamin-sensitive small conductance Ca(2+)-activated K(+) channels (SK channels) in the mouse intestine. SK3-immunoreactivity (IR) was detected in both ileum and colon. Double staining experiments showed that SK3-IR was colocalized with prolyl 4-hydroxylase (PH(alpha))-IR, but not with c-Kit-IR which are markers of fibroblast cells and the interstitial cells of Cajal (ICC), respectively. Although SK3-IR was colocalized with vimentin-IR, which is another marker of ICC, the reactivity of SK3-immunopositive cells was weaker than that of ICC. The SK3-immunopositive cells were similarly present in the intestine of c-Kit mutant mice (W/W(V)), in which ICC were absent, and its wild-type mice. The immuno-electron microscopic analysis indicated that SK3 was localized in the cells that had some similar morphological features to ICC, but obviously different from ICC. The SK3-immunopositive cells had gap junctions with the smooth muscle cells. The gap junctions were smaller than those between ICC and smooth muscle cells. These results indicate expression of SK3 in fibroblast-like cells, but not in ICC, and suggest participation of the cells in the intestinal motility.

The site where newly synthesized ATP is necessary for tension development in alpha-toxin permeabilized preparations of rat proximal colon

Since it was suggested in our previous study that ATP newly synthesized from ADP and phosphocreatine (PCr) by creatine kinase had an important role in Ca2+-induced phasic contraction in alpha-toxin permeabilized smooth muscle of rat proximal colon, we studied the role of newly synthesized ATP on myosin ATPase activity, by assessing a rate of force development as an index of myosin ATPase activity. The alpha-toxin-permeabilized preparations were thiophosphorylated by treatment with ATPgammaS. After the thiophosphorylation, the contraction induced by ATP plus PCr in the absence of Ca2+ reached the maximum at 30 s. When PCr was omitted from the bathing solution, the initial rate of the contraction was significantly slower, while the level of myosin light chain thiophosphorylation remained unchanged. An inhibitor of creatine kinase slowed the initial contractile rate to a rate similar to that induced by ATP alone. ADPbetaS had no effect on ATP plus PCr-induced contraction, suggesting that accumulation of ADP does not affect the initial rate of the contraction. PCr alone did not contract the thiophosphorylated-preparations. However, in the presence of ADP, PCr induced contraction at the initial rate which was slower than that induced by ATP plus PCr. These results indicate that newly synthesized ATP together with preexisting ATP is utilized as a substrate for myosin ATPase.

A possible role of neurotensin in NANC relaxation of longitudinal muscle of the jejunum and ileum of Wistar rats

The mediators of nonadrenergic, noncholinergic (NANC) relaxation in longitudinal muscle of the jejunum and ileum of Wistar rats were examined in vitro. Treatment of the jejunal and ileal segments with alpha-chymotrypsin resulted in decreases in the NANC relaxations induced by electrical field stimulation (EFS) by about one half. The NANC relaxations were also decreased by about one half after the segments had been desensitized to neurotensin. A neurotensin receptor antagonist, SR48692 (10 microM) inhibited the NANC relaxation by 56 and 34% in the jejunal and ileal segments, respectively. An inhibitor of small conductance Ca2+ -activated K+ channel (SK channel), apamin (100 nM) also inhibited the NANC relaxation by 83 and 63%, respectively. Exogenous neurotensin-induced relaxations of the two segments were abolished by apamin. In the ileal segments, N(G)-nitro-L-arginine (L-NOARG, 100 micro M), inhibited the NANC relaxation by 43%. L-NOARG, but not apamin, further inhibited the relaxation which persisted after the desensitization to neurotensin. Apamin with SR48692 inhibited the relaxation only to the same extent as apamin alone. EFS induced inhibitory junction potentials (i.j.ps) in the longitudinal muscle cells of the ileum. I.j.ps consisted of a rapid and a delayed phase. L-NOARG significantly inhibited only the delayed phase. EFS induced only a rapid i.j.ps in the jejunum. SR48692 and apamin inhibited the i.j.ps. These findings suggest that neurotensin and unknown substance(s) mediate NANC relaxation via SK channels in the jejunum of Wistar rats, and that neurotensin via SK channels and nitric oxide not via SK channels separately mediate the relaxation in the ileum.

PAC1 receptor-mediated relaxation of longitudinal muscle of the mouse proximal colon

Since pituitary adenylate cyclase-activating polypeptide (PACAP) was shown to partially mediate nonadrenergic, noncholinergic (NANC) relaxation of longitudinal muscle of the proximal colon of ICR mice, we further studied the receptor subtype activated by PACAP by using a mutant mouse whose PAC1 receptors are markedly reduced. In wild-type mice, the PACAP-mediated component of NANC relaxation was 33%, but it was absent in the mutant mice. The potency of exogenous PACAP in inducing relaxation in the mutant mice was one hundredth of that in wild-type mice. VPAC1 and VPAC2 receptors were not suggested to have any role in the relaxation. These results suggest that PACAP mediates NANC relaxation of longitudinal muscle of mouse proximal colon via PAC1 receptors.

High dorsal drainage routes of Spiegel's lobe

BACKGROUND/PURPOSE

The venous drainage from Spiegel's lobe to the terminal portion of the hepatic veins has been described in the literature, but its morphology remains unclear.

METHODS

We examined 42 dissected liver specimens and 38 cast specimens.

RESULTS

In 8 of the 42 dissected liver specimens and 5 of the 38 cast specimens we found atypical but thick (over 3 mm) caudate veins that drained Spiegel's lobe and emptied into the terminal portion (along the most proximal 5-mm course) of the middle hepatic vein (MHV) or the inferior vena cava (IVC) near the MHV terminal (less than 10 mm from the MHV). We termed these the superior caudate vein. This vein ran upward between the caudate portal branches of the left and hilar bifurcation origins or through the territory of the left origin. The superior caudate vein, consistently coexisted with the typical vein(s). We also found several analogues of the superior caudate vein, such as the cranially shifted opening of the typical caudate vein and relatively thick proximal tributaries of the MHV from Spiegel's lobe.

CONCLUSIONS

Although the superior caudate vein, if present, seemed to have a large role in the venous drainage of the lobe, its incidence seemed to be too low for clinical relevance.

Specific localization of an inwardly rectifying K(+) channel, Kir4.1, at the apical membrane of rat gastric parietal cells; its possible involvement in K(+) recycling for the H(+)-K(+)-pump

Hydrochloric acid (HCl) is produced in parietal cells of gastric epithelium by a H(+)-K(+) pump. Protons are secreted into the gastric lumen in exchange for K(+) by the action of the H(+)-K(+)-ATPase. Luminal K(+) is essential for the operation of the pump and is thought to be supplied by unidentified K(+) channels localized at the apical membrane of parietal cells. In this study, we showed that histamine- and carbachol-induced acid secretion from isolated parietal cells monitored by intracellular accumulation of aminopyrine was depressed by Ba(2+), an inhibitor of inwardly rectifying K(+) channels. Among members of the inwardly rectifying K(+) channel family, we found with reverse transcriptase-polymerase chain reaction analyses that Kir4.1, Kir4.2 and Kir7.1 were expressed in rat gastric mucosa. With immunohistochemical analyses, Kir4.1 was found to be expressed in gastric parietal cells and localized specifically at their apical membrane. The current flowing through Kir4.1 channel expressed in HEK293T cells was not affected by reduction of extracellular pH from 7.4 to 3. These results suggest that Kir4.1 may be involved in the K(+) recycling pathway in the apical membrane which is required for activation of the H(+)-K(+) pump in gastric parietal cells.

Effect of 1DMe, a neuropeptide FF analog, on acetylcholine release from myenteric plexus of guinea pig ileum

Since neuropeptide FF (NPFF) is a putative neurotransmitter to exert anti-opioid activity, we examined the effects of [D-Tyr', (NMe)Phe3]neuropeptide FF (IDMe), a stable NPFF analog, on acetylcholine (ACh) release from a longitudinal muscle-myenteric plexus (LMMP) preparation of guinea pig ileum in which opioids were known to inhibit ACh release when muscarinic autoinhibition was not fully activated. In the presence of atropine, 1DMe increased spontaneous and electrical field stimulation (EFS)-evoked ACh release in a concentration-dependent manner. Naloxone also increased ACh release. The stimulatory effects of 1DMe and naloxone were not additive. In the absence of atropine, 1DMe did not affect ACh release. Morphine decreased spontaneous and EFS-evoked ACh release in the presence of 1 microM atropine. 1DMe as well as naloxone counteracted the inhibitory effects of morphine on EFS-evoked ACh release. The combination of 1DMe and naloxone was not more inhibitory than either drug alone. 1DMe had no appreciable effect on norepinephrine-induced inhibition of spontaneous and EFS-evoked ACh release. These results first demonstrated the effects of a NPFF analog on neurotransmitter release: 1DMe had a stimulatory effect on spontaneous and EFS-induced ACh release from the LMMP preparation of guinea pig ileum, probably by counteracting the inhibitory effect of endogenous opioids on ACh release.

Origin of Ca2+ necessary for carbachol-induced contraction in longitudinal muscle of the proximal colon of rats

The origin of Ca2+ necessary for carbachol (CCh)-induced contraction of longitudinal muscle of the proximal colon of rats was studied. CCh induced contraction of the muscle consisting of two phases, phasic and tonic phases, with a concomitant biphasic increase in [Ca2+]i. After removal of Ca2+ from the bathing solution of the colonic segments, CCh-induced contraction was rapidly inhibited; there was almost complete inhibition 1 min after the removal. Nicardipine, a blocker of voltage-dependent calcium channel, also significantly inhibited CCh-induced contraction. On the other hand, treatment of the colonic segments with thapsigargin, an inhibitor of sarcoplasmic reticulum (SR) Ca2+-ATPase, did not significantly affect the contraction except causing a slight decrease in the rate of contraction. These results suggest that Ca> entering through voltage-dependent calcium channels, but not released from SR, is essential for CCh-induced contraction of longitudinal muscle of the proximal colon of rats. This strict dependency of the CCh-induced contraction on extracellular Ca2+ was discussed in relation to the results obtained in the fundus of rats.

NGF induces neurite outgrowth via a decrease in phosphorylation of myosin light chain in PC12 cells

The relationship between phosphorylation of myosin light chain (MLC) and neurite outgrowth induced by nerve growth factor (NGF) was studied in PC12 cells. Inhibitors of Rho kinase, HA-1077 or Y-27632 also induced neurite outgrowth. As already reported botulinum exoenzyme C3 which inactivates Rho protein also induced neurite outgrowth. Calyeulin A, an inhibitor of phosphatase counteracted both NGF- and C3- induced neurite outgrowth. Treatments of both NGF and C3 resulted in significant and transient decrease in phosphorylated MLC. These results suggest that NGF induces neurite outgrowth of PC12 by a transient decrease in phosphorylated MLC which is brought about by activation of MLC phosphatase via inhibition of Rho-Rho kinase pathway.

Expression of Ca(2+)-activated K(+) channels, SK3, in the interstitial cells of Cajal in the gastrointestinal tract

A role for small-conductance Ca(2+)-activated K(+) (SK) channels on spontaneous motility of the gastrointestinal tract has been suggested. Although four subtypes of SK channels were identified in mammalian tissues, the subtypes of SK channel expressed in the gastrointestinal tract are still unknown. In this study, we investigated the expression and localization of SK channels in the gastrointestinal tract. RT-PCR analysis shows expression of SK3 and SK4 mRNA, but not SK1 or SK2 mRNA, in the rat intestine. SK3 immunoreactivity was detected in the myenteric plexus and muscular layers of the stomach, ileum, and colon. SK3-immunoreactive cells were stained with antibody for c-kit, a marker for the interstitial cells of Cajal (ICC), but not with that for glial fibrillary acidic protein in the ileum and stomach. Immunoelectron microscopic analysis indicates that SK3 channels are localized on processes of ICC that are located close to the myenteric plexus between the longitudinal and circular muscle layers and within the muscular layers. Because ICC have been identified as pacemaker cells and are known to play a major role in generating the regular motility of the gastrointestinal tract, these results suggest that SK3 channels, which are expressed specifically in ICC, play an important role in generating a rhythmic pacemaker current in the gastrointestinal tract.

Blood supply to the duodenal papilla and the communicating artery between the anterior and posterior pancreaticoduodenal arterial arcades

The communicating artery (ComA) between the anterior and posterior pancreaticoduodenal arterial arcades is little understood, although it has been described several times during the past 100 years. In 44 of 51 cadaveric specimens in the present study, the typical ComA was observed to pass between the major and accessory pancreatic ducts. In addition, a second ComA was sometimes found crossing inferior to the major pancreatic duct. The typical ComAs often (36 of the 44) issued papillary branch(es). Although direct papillary branches of the posterior arcade were often observed to either coexist with (9 specimens) or exist independently (4 specimens), the ComA-derived branch seemed to be critical for papillary blood supply, because of its shorter length, greater thickness, and higher frequency. Moreover, the typical ComA could be a good landmark during limited pancreatic resection, such as duodenum-preserving subtotal resection of the pancreatic head or pancreatic segment resection, because the artery is likely to be an indicator of the borders between the celiac and superior mesenteric arterial territories, as well as those between the ventral and dorsal segments of the pancreas.

Possible role of orexin A in nonadrenergic, noncholinergic inhibitory response of muscle of the mouse small intestine

The effect of a novel peptide, orexin A, on longitudinal muscle of ICR mouse small intestine was examined in vitro. Exogenous orexin A induced a transient contraction in duodenal, jejunal and ileal segments. Atropine and tetrodotoxin completely inhibited the contractions. Contraction of longitudinal muscle of jejunal segments induced by electrical field stimulation was still observed after the jejunal segment had been desensitized to orexin A, suggesting that orexin A is not a final neurotransmitter to induce the contraction. On the other hand, in the presence of atropine and guanethidine, orexin A induced a transient gradual relaxation in duodenal, jejunal and ileal segments. Electrical field stimulation also induced significant relaxation of the muscle in jejunal segments. The electrical field stimulation-induced relaxation was inhibited by 55% after the desensitization of the segments to orexin A. Although the electrical field stimulation-induced relaxation was inhibited by 47% by a nitric oxide synthesis inhibitor, NG-nitro-L-arginine (L-NOARG), orexin desensitization did not affect the relaxation which persisted after L-NOARG treatment. The exogenous orexin A-induced relaxation was completely inhibited by L-NOARG. The results suggest that orexin A partially mediates nonadrenergic, noncholinergic (NANC) relaxation via activation of nitrergic neurones in longitudinal muscle of ICR mouse small intestine.

Ventral margin of the paracaval portion of human caudate lobe

The topographic anatomy of the ventral margin of the caudate lobe of the human liver is still obscure. We hypothesized the existence of a "precaudate plane", as a flat or slightly curved plane defined by the ventral margins of both the ligamentum venosum and hilar plate. Using 61 cadaveric liver specimens, without great differences in external shape or significant variations in the hilar bifurcation, we examined whether the paracaval caudate branches (PCs) ran through the plane to the ventral side. In 22 of the 61 specimens (36.1%), the PC extended over the plane for less than 10 mm (10 specimens), for 10-20 mm (7 specimens), or for more than 20 mm (5 specimens). The ventral extension consistently included the dome-like area under the terminals of the middle and right hepatic veins. Therefore, the ventrally extended PCs often interdigitated with these veins and their tributaries. The ventral extension often reached the upper, diaphragmatic surface. However, several branches were too difficult to discriminate from the PC, especially those with morphologies intermediate between the PC and segmental portal branches to S4 or S2. We discuss how to identify and manage the ventrally extended PCs before and during surgery.

Sepsis and cholestasis: basic findings in the sinusoid and bile canaliculus

It is well known that the liver plays a major role in the clearance of systemic toxemia and is postulated as a regulational organ in the host-defense system. The well-controlled interaction between hepatic parenchymal cells and sinusoidal lining cells including macrophages and Kupffer cells can systematically regulate even critical infections. However, when patients are under the overload condition caused by severe infection, rejection of a transplanted liver and other hapatic dysfunction often are experienced following surgery. Among various signs and symptoms of hepatic dysfunction, progressive cholestasis is recognized as a polarized representation of the irreversible changes in hepatic constitutional cellular functions, especially in hepatic parenchymal cells. Bile canaliculi, the smallest components of the biliary tree, lie between the apical surfaces of adjacent hepatocytes. Septic cholestasis might be a result of disturbance of the total bile canalicular system, i.e., bile secretion, canalicular contraction, and so on. Recently, the molecular biology of the hepatocellular transport system has become better understood, and the pathophysiological condition of cholestasis can be explained as a representation of the intracellular molecular transcriptional system. Cellular changes in surgical cholestasis and molecular findings concerning the bile canaliculus are introduced in this article.

Ramification pattern and topographical relationship between the portal and hepatic veins in the left anatomical lobe of the human liver

Sixty-one human livers obtained from donated Japanese adult cadavers were dissected to reveal the ramification pattern of the portal and hepatic veins, and their topographical relationship in the left anatomical lobe. The segmental portal vein supplying S2 (P2) tended to form a single stem, whereas that of S3 (P3) was usually double. An intermediate branch between P2 and P3 was observed in 23.0% of livers. In spite of variation between livers, definite P2 and P3 were identified in 47 specimens. One tributary of the left hepatic vein (LHV) was usually present for drainage of S2, and two tributaries were present for S3 (sometimes also for S2 and/or S4). The latter two tributaries of the LHV and the two subsegmental branches of S3 showed three patterns of three-dimensional interdigitations. From these results, the portal vein system did not seem to have a two segmental composition (i.e., S2 and S3) in 23.0% of specimens, whereas the hepatic vein system did not have an intersegmental course in 23.4%. Thus, there were obvious limitations in using each system to determine the liver segment. Taking the overlapping cases into consideration, the left anatomical lobe of 41.0% of specimens did not seem to fit the definition of Couinaud's liver segment. In addition, four patterns of fissure vein (or scissural vein), > 5 mm in diameter at its terminal, were identified: (1) middle hepatic vein type (left median vein, 9.8%); (2) LHV type (left medial vein, 41.0%); (3) true fissure vein (3.3%); and (4) absent cases (45.9%). The former two types also suggested limitations of the hepatic vein system as an indicator of the segmental border.

Effect of 1DMe, a neuropeptide FF analog, on acetylcholine release from myenteric plexus of guinea pig ileum

Since neuropeptide FF (NPFF) is a putative neurotransmitter to exert anti-opioid activity, we examined the effects of [D-Tyr', (NMe)Phe3]neuropeptide FF (IDMe), a stable NPFF analog, on acetylcholine (ACh) release from a longitudinal muscle-myenteric plexus (LMMP) preparation of guinea pig ileum in which opioids were known to inhibit ACh release when muscarinic autoinhibition was not fully activated. In the presence of atropine, 1DMe increased spontaneous and electrical field stimulation (EFS)-evoked ACh release in a concentration-dependent manner. Naloxone also increased ACh release. The stimulatory effects of 1DMe and naloxone were not additive. In the absence of atropine, 1DMe did not affect ACh release. Morphine decreased spontaneous and EFS-evoked ACh release in the presence of 1 microM atropine. 1DMe as well as naloxone counteracted the inhibitory effects of morphine on EFS-evoked ACh release. The combination of 1DMe and naloxone was not more inhibitory than either drug alone. 1DMe had no appreciable effect on norepinephrine-induced inhibition of spontaneous and EFS-evoked ACh release. These results first demonstrated the effects of a NPFF analog on neurotransmitter release: 1DMe had a stimulatory effect on spontaneous and EFS-induced ACh release from the LMMP preparation of guinea pig ileum, probably by counteracting the inhibitory effect of endogenous opioids on ACh release.

Mechanism of a nitric oxide donor NOR 1-induced relaxation in longitudinal muscle of rat proximal colon

We previously suggested that nitric oxide (NO)-mediated relaxation of the rat proximal colon is not associated with change in cyclic GMP content. We further studied the intracellular mechanism of NO-induced relaxation by measuring changes in tension and intracellular Ca2+ concentration ([Ca2+]i), simultaneously. NOR 1, NO donor, relaxed the longitudinal muscle of the rat proximal colon, which was precontracted by carbachol, with a concomitant decrease in [Ca2+]. ODQ, an inhibitor of soluble guanylate cyclase, partially inhibited the relaxant effect of only higher concentrations of NOR 1, but Rp-8-Br-cGMPS, an inhibitor of cyclic GMP-dependent protein kinase (PKG), did not have any effects on the relaxant effect of NOR 1. When the preparations were transferred to normal solution after the treatment with thapsigargin, an inhibitor of sarcoplasmic reticulum (SR) Ca2+-ATPase, in the absence of Ca2+, contraction with a concomitant increase in [Ca2+]i occurred. NOR 1 did not show significant effects on the tension and [Ca2+]i in thapsigargin-treated preparations. In high K+-precontracted preparations, NOR 1 relaxed the preparations with a slight change in [Ca2+]i. The relaxant effect was significantly inhibited by ODQ and Rp-8-Br-cGMPS. These results suggest that NO induces the relaxation preferentially by acting thapsigargin-sensitive function of SR and in turn decreasing [Ca2+]i, although a cyclic GMP-PKG pathway is suggested under the experimental conditions of a high K+ concentration.

A novel experimental mouse model of peritoneal dissemination of human gastric cancer cells: analysis of the mechanism of peritoneal dissemination using cDNA macroarrays

We established a new cell line, NUGC-3P4T, with high peritoneal metastatic disseminating potential in nude mice. NUGC-3P4T cells were derived from the human gastric carcinoma line NUGC-3, which has low capacity for peritoneal dissemination. NUGC-3P4T cells developed peritoneal dissemination in 10 / 10 (100%) mice, whereas the parental NUGC-3 cells developed dissemination in 1 / 5 (20.0%) mice. The metastatic foci in the peritoneum showed essentially the same histological appearance as those induced by parental cells. The tumorigenicity, the motile activity and the adhesive activity to the laminin of NUGC-3P4T cells were stronger than those of NUGC-3 cells. Production of IL-8 was significantly higher in NUGC-3P4T than in NUGC-3. cDNA macroarrays analysis showed that a variety of cytokines, interleukins, and other immunomodulators and their receptors were up- or down-regulated at the mRNA level in NUGC-3P4T cells, compared with NUGC-3 cells. Thus, this unique cell line and in vivo model might be useful to study the biology of peritoneal dissemination of human gastric cancer.

Adenosquamous carcinoma of the colorectum: report of two cases

Adenosquamous carcinomas of the colorectum are rare neoplasms. Our experience with two cases is presented in this paper. One patient, who complained of bloody stool, was found to have adenocarcinoma in the sigmoid colon. He received a laparoscopy-assisted sigmoidectomy. The histological examination revealed that the tumor was adenosquamous carcinoma. To date, he has survived six months post operatively without evidence of recurrence. The other patient, who complained of anal bleeding, was found to have rectal adenocarcinoma and received a low anterior resection. Histological examination revealed that the tumor was an adenosquamous carcinoma. He remains alive, with no evidence of recurrence, nine years post operatively. Both cases showed paracolic lymph node metastasis. Because of its very low incidence, the histogenesis, malignancy and prognosis of this disease remain unclear. Thus, further clinical and histological study of this disease entity is required.