Toshihiro Uesaka

High expression of MCL1 gene related to vascular endothelial growth factor is associated with poor outcome in non-Hodgkin's lymphoma

Summary. We evaluated the level of MCL1 gene expression using quantitative reverse transcription polymerase chain reaction in lymph nodes of patients with non‐Hodgkin lymphoma (NHL). MCL1 expression in patients in complete remission (CR) was significantly lower than in patients with progressive disease (PD, P = 0·0043). The disease–free survival rate was significantly higher in patients with MCL1 levels below the median level (P = 0·007). We also found that the level of expression of MCL1 mRNA was related to that of vascular endothelial growth factor mRNA in NHL lymph nodes. Our data suggest that the MCL1 expression level could be considered a prognostic factor in NHL.

Cdx2 homeodomain protein regulates the expression of MOK, a member of the mitogen‐activated protein kinase superfamily, in the intestinal epithelial cells

Regulatory protein kinases are involved in various cellular processes such as proliferation, differentiation, and apoptosis. Using cDNA differential display, we identified MOK, a member of the mitogen‐activated protein kinase superfamily, as one of the genes induced by a caudal‐related homeobox transcription factor, Cdx2. Analysis of the 5′‐flanking region of the MOK gene led to the identification of primary Cdx2 responsive element, and an electrophoretic mobility shift assay indicated that Cdx2 binds to that element. The interaction of Cdx2 with the MOK promoter region was further confirmed in vivo by chromatin immunoprecipitation assays. The expression of MOK mRNA and protein was limited to the crypt epithelial cells of the mouse intestine. We also determined the MOK activity associated with the growth arrest and induction of differentiation by sodium butyrate or Cdx2 expression in the human colon cancer cell line HT‐29. Taken together, these data indicate that MOK is a direct target gene for Cdx2, and that MOK may be involved in growth arrest and differentiation in the intestinal epithelium.

Effects of Eel Neuropeptide Y on Ion Transport Across the Seawater Eel Intestine

Abstract A neuropeptide Y (eNPY) was isolated from the intestinal extract of eels. This peptide enhanced significantly the serosa-negative transepithelial potential difference (PD) and short-circuit current (lsc) across the intestine of the seawater eel after pretreatment with isobutylmethylxanthine, serotonin and methacholine. The effects of eNPY on the lsc were concentration-dependent with a threshold concentration of 3×10−9 M and a maximal effect at 3×10−7 M. Similar concentration-responce curve was obtained by porcine peptide YY (pPYY). Since 9 amino acid residues are replaced in the pPYY, this result indicates that these substitutions do not change the potency and the efficacy. These stimulatory actions of eNPY were not blocked by tetrodotoxin, an inhibitor of neural firing, or yohimbine, an &agr;2-adrenoceptor antagonist, indicating that eNPY acts without enteric neural firing or catecholamine release. When eNPY and adrenaline (AD) were applied simultaneously, the effects were additive only at lower dosage (3×10−8 M for eNPY, 3×10−8 M for AD), but not at high dosage (10−6 M eNPY, 10−7 M AD). The ceiling effect at high dosage suggests that these two regulators act through common signal transduction systems and affect the Na+-K+-Cl− cotransport system, since both effects were completely blocked by bumetanide, a specific inhibitor of Na+-K+-Cl− cotransporter.

Gastric tumor induction by 1,2-dimethylhydrazine in Wistar rats with intestinal metaplasia caused by X-irradiation

Five‐week‐old male Wistar rats were X‐irradiated with a total of 20 Gy in 2 equal fractions at a 3‐day interval. 1,2‐Dimethylhydrazine (DMH) solution was injected i.m. into the back musculature at a dose of 20 mg/kg body weight weekly for 10 weeks, beginning 20 weeks after the final irradiation. Twelve months after the initial carcinogen treatment, tumors in the fundus of the glandular stomach were observed in 5 of 23 animals receiving both X‐irradiation and DMH treatment. No tumors of the glandular stomach were observed in the DMH and X‐ray alone or nontreatment groups. It is concluded that the presence of intestinal metaplasia may increase sensitivity to the induction of gastric tumors by carcinogens like DMH.

Regulation of atrial contraction in the seawater-adapted eel, Anguilla japonica☆

Abstract The atrium isolated from the seawater-adapted eel beats spontaneously in normal Ringer solution for more than 10 hr. The strength of beating was inhibited by acetylcholine (ACh) and the inhibitory effects were blocked by atropine, a muscarinic ACh-receptor antagonist, indicating existence of muscarinic ACh-receptor on the atrium. The atrial contractility was stimulated by catecholamines and their agonists; the order of potency being isoproterenol > adrenaline (AD) = noradrenaline (NA) > phenylephrine > clonidine. The stimulatory effects of AD was completely blocked by propranolol, a β-adrenoceptor antagonist, but not by phentolamine, an α-adrenoceptor antagonist. These data were consistent with characteristics of β-adrenoceptors. Further characterization of the β-receptor was not attempted. The positive inotropic and chronotropic actions of AD were not completely blocked either by atenolol, a β1-adrenoceptor antagonist, or by ICI 118551, a β2-adrenoceptor antagonist. When electrical current with a short duration (0.25 msec) was passed through the atrium, the beating was inhibited initially, then enhanced later. The initial inhibition was inhibited by atropine and the later enhancement was blocked by propranolol. These results indicate that the electrical stimulation releases ACh and catecholamine(s) from the nerve endings. The positive inotropic and chronotropic effects of catecholamines were mimicked by tyramine, a catecholamine releaser from sympathetic nerve endings.

Structure and function of a pentapeptide isolated from the gut of the eel

A novel peptide, H-Gly-Phe-Trp-Asn-Lys-OH, was isolated from eel guts. This peptide, termed eel intestinal pentapeptide (EIPP), enhanced the frequency of the spontaneous contractions and increased the basal tone of the circular muscle of the esophagogastric junction. Furthermore, EIPP enhanced the spontaneous contractions of the longitudinal muscle strips of the gut and stomach, and of the circular muscle of the gastro-intestinal junction. The peptide may be a physiological regulatory peptide in the gastro-intestinal tract of the eel.

Atrium Contributes to Osmoregulation in Eels Acclimated to Sea Water

Abstract Since highly concentrated NaCl is suspected to enter into the heart of the seawater eels, effects of high NaCl concentration on the atrial beating was examined, and plasma ion concentrations and osmolality were measured simultaneously in the blood collected from the bulbus arteriosus and from the caudal vessels. When 100 mmole l−1 NaCl was added to the incubation medium, atrial contraction was enhanced significantly. Similar enhancement in the atrial contractility was also observed after addition of NaCH3SO4 (100 mmole l−1) or Tris HCl (100 mmole l−1), indicating that Na+ and Cl− are not indispensable for the positive inotropic effect. Furthermore, an addition of sucrose (200 mmole l−1) also enhanced the contraction. Inversely, hypoosmotic solution reduced the atrial contraction. These results indicate that the eel atrium is sensitive to environmental osmolarity. The eel atrium responses even at 20 mmole l−1 sucrose. Such an inotropic effect of sucrose was not depressed after blocking adrenoceptor with betaxolol, a β1-adrenoceptor antagonist, indicating that the effect is not due to adrenaline release from nerve endings. Plasma osmolality and Na+ concentration were higher in bulbus arteriosus than in caudal vessels, indicating that the eel heart is really exposed to hyperosmotic blood in sea water. The osmotically enhanced atrial contraction may increase the cardiac outflow into the gill. Such property of the atrium would have clear advantages for seawater teleosts, since the concentrated NaCl from the esophagus can be excreted immediately through the gill, without circulating their body, and blood homeostasis can be maintained efficiently.