[Cell signal transduction and inositol 1,4,5-triphosphate].
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Animals↗
Biomedical subjects
M Hirata
Publications and source records attributed to M Hirata.
Study of new prognostic factors of esophageal variceal rupture by use of image processing with a video endoscope.
BACKGROUND: We studied new prognostic factors of esophageal variceal rupture by analyzing electronic video images of esophageal varices in 30 patients with portal hypertension. METHODS: Fifteen of the patients were emergency or elective cases (bleeders), and the remaining 15 were prophylactic cases (nonbleeders). A comparison was made between the bleeders and nonbleeders in terms of endoscopic findings and the image processing data, especially variceal color tone and red color sign. RESULTS: Endoscopic findings based on the general rules prepared by the Japanese Research Society for Portal Hypertension showed no significant difference between the two groups. However, with regard to the image processing data, both the ratio of red signal and the ratio of value were significantly lower in bleeders than in nonbleeders. In addition, the area ratio of red color sign was significantly higher in the former than in the latter. A follow-up study of nonbleeders also indicated that image processing data were more reliable than traditional endoscopic rules. CONCLUSIONS: By adding these image processing data to the traditional general rules for recording endoscopic findings, it is possible to select patients with varices that have a higher risk of rupture.
Esophageal and Gastric Varices↗
Dose-dependent testicular toxicity of propylene oxide in rats induced by repeated intraperitoneal injections.
The dose-dependent testicular toxicity of propylene oxide (PO) was evaluated in male Wistar rats when administered by intraperitoneal injections. In 23 mg/kg, 47 mg/kg, and 93 mg/kg groups, PO was given three days a week for six weeks, while PO was given three days a week for two weeks plus once a week after the third week in a 186 mg/kg group. In the 186 mg/kg group, the epididymal weight and sperm count in the body plus tail of the epididymis decreased, while the rate of sperm with morphological abnormalities increased significantly. The number of sperm with an immature head increased slightly, although significantly, even in the 47 mg/kg group and a dose-dependent effect could be seen. The serum testosterone concentration did not change significantly and there were no apparent histopathological changes in Leydig cells in any of the treatment groups. This is the first detailed study concerning the dose-dependent testicular toxicity of PO.
Animals↗
DL-myo-inositol 1,2,4,5-tetrakisphosphate, a potent analog of D-myo-inositol 1,4,5-trisphosphate.
Synthetic DL-myo-inositol 1,2,4,5-tetrakisphosphate (DL-Ins-(1,2,4,5)P4) functioned as a full agonist, with only 3-fold less potency than D-Ins(1,4,5)P3 in eliciting the release of Ca2+ from nonmitochondrial pools of permeabilized rat basophilic leukemic cells. DL-Ins(1,2,4,5)P4 inhibited the binding of D-[3H]Ins(1,4,5)P3 to the purified D-Ins(1,4,5)P3 receptor with almost the same potency as seen for the Ca2+ release. This compound inhibited the hydrolysis of D-[3H]Ins(1,4,5)P3 to D-[3H]Ins(1,4)P2 catalyzed by erythrocyte ghosts, with a Ki value of as low as 1.4 microM, but it could not serve as a substrate for the same enzyme. D-Ins(1,4,5)P3 3-kinase in rat brain cytosol did not recognize the compound at concentrations up to 30 microM. Thus, it would appear that DL-Ins(1,2,4,5)P4 can serve as a potent and long lasting experimental and pharmacological tool for stimulating D-Ins(1,4,5)P3-mediating processes.
Animals↗
[Idiopathic eosinophilic pleural effusion].
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Eosinophilia↗
Characterization and chromosomal mapping of the human thromboxane A2 receptor gene.
The human thromboxane A2 gene, present as a single copy, spans over 15 kilobases (kb) and contains 3 exons divided by 2 introns. The first intron, intron 1, exists in the 5'-noncoding region, 83 base pairs upstream from the ATG start site and is 6.3 kb long. Intron 2 with a length of 4.3 kb is located at the end of the sixth transmembrane region, thereby separating it from the downstream coding sequences including the seventh transmembrane region and the 3'-untranslated region. By rapid amplification of 5'-cDNA ends, transcription initiation sites starting in two different putative promoter regions were determined. In the 5'-flanking region of these transcription initiation sites, no typical TATA box exists. The major promoter, the promoter region I, contains four potential SP-1 binding sites and several potential binding sites for other transcription factors. By polymerase chain reaction analysis, a small portion of the RNA transcribed from this gene was shown to contain an additional 115-base pair long noncoding exon, exon 1b, which is located in intron 1. No additional exon in intron 2 was detectable, indicating that a single type of thromboxane A2 receptor protein is encoded by this gene. Chromosomal localization was carried out by fluorescence in situ hybridization of cloned genomic DNA to the metaphase chromosome. The gene was assigned to 19p13.3 of human chromosome.
Base Sequence↗
Thromboxane A2 receptor is highly expressed in mouse immature thymocytes and mediates DNA fragmentation and apoptosis.
We have recently revealed that the thymus is the organ showing the highest expression of thromboxane (TX) A2 receptor in mice. In this study, thymic cell populations expressing the receptor were identified, and the effects of a TXA2 agonist on these cells were examined. Radioligand binding using a TXA2 receptor-specific radioligand revealed a single class of binding sites in the thymocytes with an affinity and specificity identical to those reported for the TXA2 receptor. The receptor density in these cells was comparable to that seen in blood platelets. This receptor is most highly expressed in CD4-8- and CD4+8+ immature thymocytes, followed by CD4+8- and CD4-8+ cells. The receptor density in splenic T cells was less than one fifth of that in CD4+8+ cells and no binding activity was detectable in splenic B cells. The addition of a TXA2 agonist, STA2, to thymocytes induced the disappearance of the CD4+8+ cells in a time- and concentration-dependent manner and caused DNA fragmentation. These changes were blocked by a specific TXA2 antagonist, S-145. These results demonstrate that TXA2 induces apoptotic cell death in immature thymocytes by acting on the TXA2 receptor on their cell surface and suggest a role for the TXA2/TXA2 receptor system in the thymic micro-environment.
Animals↗
Roles for hydroxyl groups of D-myo-inositol 1,4,5-trisphosphate in the recognition by its receptor and metabolic enzymes.
Positional isomers of D-myo-inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), Ins(1,4,6)P3, and Ins(1,3,6)P3 were examined to explore the roles for hydroxyl groups of Ins(1,4,5)P3, recognized by metabolic enzymes and by the receptor. Ins(1,4,6)P3 and Ins(1,3,6)P3 inhibited the dephosphorylation of [3H] Ins(1,4,5)P3 by the 5-phosphatase present in erythrocyte ghosts. The Ki value for the former compound was slightly lower than that for Ins(1,4,5)P3, while that for the latter compound was higher. In an assay of [3H] Ins(1,4,5)P3 3-kinase catalyzed by rat brain cytosol, Ins(1,4,6)P3 was as potent as Ins(1,4,5)P3 in inhibiting the phosphorylation, whereas Ins(1,3,6)P3 at concentrations up to 30 microM, was without effect. Ins(1,4,6)P3 and Ins(1,3,6)P3 at higher concentrations were effective in inhibiting [3H]Ins(1,4,5)P3 binding to purified Ins(1,4,5)P3 receptor. It would thus appear that the 2- and 3-hydroxyl groups of Ins(1,4,5)P3 are not primarily involved in recognition by metabolic enzymes, while 6-hydroxyl is slightly or severely involved in recognition by the phosphatase or kinase, respectively. On the other hand, although both 3-OH and 6-OH of Ins(1,4,5)P3 are important in binding by the Ins(1,4,5)P3 receptor to evoke the release of Ca2+, the 6-OH seems to be the more important.
Animals↗
Characterization of the transport system of prostaglandin A2 in L-1210 murine leukemia cells.
Prostaglandin (PG) A2 has been shown to be actively incorporated into mammalian cells and transferred to the cell nucleus. To characterize the properties of the PGA2 transfer system, we examined the status of PGA2 in L-1210 cells with modified cellular glutathione (GSH) levels. PGA2 in the cytosol fraction of the cells existed in its free-form, the GSH conjugate-form and a macromolecule associate-form (protein bound-form). When the GSH level was lowered under culture conditions, the amount of free-form increased while that of the protein bound-form was unchanged. When PGA2-loaded cells were incubated in a salt solution, free- and conjugate-forms were emitted from the cells. A concomitant decrease and increase of protein bound PGA2 in cytosol and nuclei, respectively, were observed. Subsequent studies with isolated cellular fractions revealed that PGA2 bound to cytosolic protein was transported into the nuclear interior in a temperature-dependent manner. The binding of PGA2 to the protein and subsequent transport to the nuclei were inhibited by PGJ2 and 4-hydroxy-cyclopentenone, but not by PGB2, PGD2, PGE2, PGF2 alpha, arachidonic acid or oleic acid. N-Ethylmaleimide (NEM) and p-chloromercuribenzoate (PCMB) strongly interfered with these transfer processes, suggesting that sulfhydryl components are involved in the transport of PGA2. Subfractionation of cytosol by gel chromatography proved the presence of two proteins (100-150 kDa and 25-35 kDa) that are capable of transporting PGA2 to cell nuclei. Though 40-45 kDa proteins, which correspond to GSH S-transferases, bound to PGA2, they lacked the nuclear transport activities.
Animals↗
Two isoforms of the EP3 receptor with different carboxyl-terminal domains. Identical ligand binding properties and different coupling properties with Gi proteins.
Functional cDNA clones for two isoforms of the mouse prostaglandin E receptor EP3 subtype derived from alternative RNA splicing were obtained. The two isoforms are only different in the sequence of the putative cytoplasmic carboxyl-terminal tail and their hydrophobicity; one isoform, named EP3 alpha, has a hydrophilic tail, and the other, named EP3 beta, has a hydrophobic tail. When expressed, the two receptors displayed identical ligand binding properties but different responses to guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S). Without a change in the Bmax value, GTP gamma S increased Kd for prostaglandin E2 of EP3 beta and decreased that of EP3 alpha. These effects were abolished by the treatment of membranes with pertussis toxin and restored by the addition of Gi2. Although both isoforms exerted inhibition of forskolin-induced cAMP accumulation, three orders lower concentrations of agonists were required for EP3 alpha than EP3 beta for 50% inhibition of cAMP formation. A similar difference in agonist potency was observed also for agonist-induced stimulation of GTPase activity in membranes. Thus, the two receptors with different carboxyl-terminal tails show different coupling to the Gi protein, leading to the opposite responses to GTP in the ligand binding affinity and to different affinities of the agonist-occupied receptors to the G proteins.
Adenylyl Cyclases↗
Significance of subclinical entrapment of nerves in lead neuropathy.
We examined a left-handed 25-year-old man engaged for 2 years at a vinyl chloride resin factory where he had been exposed to lead stearate, a stabilizer of resin. Neurological examination revealed atrophy of small hand muscles, especially in the left dorsal interossei. Sensation of all modalities was intact. A nerve conduction study showed conduction block at the elbow, indicating possible cubital tunnel syndrome. Following CaEDTA therapy, continued recovery of conduction velocities, amplitude of compound muscle action potential, and diminution of conduction block at elbow were observed within a few months. In lead intoxication, nerves may incur mechanical damage. Subclinical entrapment may thus be an important factor leading to vulnerability of nerves in lead neuropathy.
Action Potentials↗
Effects of lead exposure on neurophysiological parameters.
To clarify the chronic effect of lead exposure on the central and peripheral nervous systems (CNS and PNS), we performed neurophysiological tests on 41 lead-exposed male workers. Unexposed workers (controls, N = 39) were examined for auditory brain stem response (ABR), and their ABR parameters were compared with those of 15 lead-exposed workers age-matched to the controls. Neurophysiological tests included those of motor and sensory nerve conduction velocity of the radial nerve (MCV, SCVwa and SCVfw), electroretinograms, pattern reversal visual evoked potential (VEP), ABR, and short-latency somatosensory evoked potentials (SLSEP). Neurophysiological parameters were analyzed by regression analysis [independent parameters: age, exposure duration, and current and time-weighted average lead concentration in whole blood (PbB and TWA-PbB)]. ABR parameters were also tested by Student's t test. Significant negative correlations were found between radial MCV and TWA-PbB and SCVwa and PbB, while significant positive correlations were found between the latency of component N145 of VEP and exposure duration and between the latency of component N20 of SLSEP and PbB. The mean of interpeak latency between component III and V of ABR of 15 lead-exposed workers was significantly prolonged compared with that of the control group. These results suggested that lead exposure has a greater effect on the conduction function in the PNS than in that of the CNS in somatosensory and auditory pathways, and inversely in visual pathway.
Adult↗
Protein kinase C-mediated inhibition of vascular smooth muscle cell proliferation: the isoforms that may mediate G1/S inhibition.
The role of protein kinase C (PKC) in the regulation of vascular smooth muscle cell proliferation was studied using not only phorbol ester but also diacylglycerol, with regard to the molecular species of PKC. Phorbol 12,13-dibutyrate (PDBu) and 1,2-dioctanoylglycerol (DOG) both potently inhibited serum-stimulated DNA synthesis and cell population doubling. The PDBu effect on DNA synthesis was maximal when applied at late G1. Neither PDBu nor DOG inhibited DNA synthesis in cells incubated with phorbol 12-myristate 13-acetate (PMA) for 24 h, which down-regulates PKC. Moreover, long exposure to PMA shortened the G1 period and the cell population doubling time. Therefore, a PKC isoform(s) that can be activated by phorbol ester and down-regulated by long exposure to PMA should be involved in the G1/S inhibition. A PKC enzyme assay of the soluble proteins extracted from late G1 cells and fractionated by anion exchange and hydroxylapatite chromatography showed that the activity eluting with PKC-alpha predominated, whereas that eluting with PKC-zeta was detectable. The former was dependent on Ca2+ and phorbol ester but the latter was not. PKC-zeta appeared to be expressed as two subspecies of M(r) 70 and 80 kDa. In cells incubated with PMA for 24 h, the activity eluting with PKC-alpha was completely abolished, whereas the significant activity eluting with PKC-zeta (70 kDa) remained. On the other hand, a relatively low, Ca(2+)-independent activity eluted with PKC-epsilon from the particulate fraction. This was reduced by long exposure to PMA, although not completely. Therefore, PKC-alpha and -epsilon may be the most probable mediators of the G1/S inhibition.
Animals↗
Comparative analysis of hepatic, pulmonary, and intestinal granuloma formation around freshly laid Schistosoma japonicum eggs in mice.
Hepatic, pulmonary, and intestinal granuloma formation was comparatively studied in mice implanted with freshly laid Schistosoma japonicum eggs. The liver and the lung showed similar kinetics of tissue reactivity, with the magnitude in the lung being of a significantly lower degree. When the footpad-swelling test was performed, the delayed-type hypersensitivity (DTH) response during hepatic granuloma formation was found to be significantly increased from the 28th day after egg implantation onward, whereas pulmonary granuloma formation showed a peak response at 14-21 days, suggesting differing kinetics of granulomatous reaction. In histologic analysis, the temporal infiltration of monocytes was revealed to correspond to the increase in the DTH response. During intestinal granuloma formation, eosinophil infiltration was the most marked feature. The present study demonstrates that throughout the course of reaction, cellular components participating in egg-granuloma formation differ greatly according to the tissues involved.
Animals↗
The human colon cancer cell line CaCo-2 produces secretory components during enterocytic differentiation.
A human colon cancer cell line CaCo-2 differentiates spontaneously by expressing enterocytic phenotypes after the confluence of the culture. The authors examined a production of secretory components (SC) by CaCo-2 in relation to its differentiation. The SC production showed an increase immediately after the cells came to confluence, and reached its peak production during the 6th to the 9th day after confluence of the culture. SC production decreased remarkably after the 10th day. On the other hand, the activity of alkaline phosphatase of CaCo-2 showed a gradual increase up to the 18th day after confluence. The production of SC was not affected by the presence of dimeric IgA in the culture. Interferon-gamma enhanced SC production of CaCo-2 with dose-dependent manner. These observations indicate that capability of SC production of CaCo-2 is enhanced in the early stage of differentiation but is reduced in the late stage. Moreover, CaCo-2 provides a useful model for studying the regulation of SC production in enterocytic differentiation.
Adenocarcinoma↗
High reactivity of [11C]CH3I with thiol group in the synthesis of C-11 labeled radiopharmaceuticals.
High reactivity of [11C]-methyl iodide ([11C]CH3I) with the thiol group was demonstrated with cysteamine and other compounds containing a thiol and another functional groups in each structure. The methylation of the thiol group in cysteamine with [11C]CH3I was very rapid at 0 degree C with no catalyst, and gave a high radiochemical yield and purity without any detectable by-product. Moreover, this reaction was not disturbed by the other functional groups, such as -NH2, -OH and -COOH in the same structure. This S-methylation reaction is very useful for producing a new radiopharmaceutical labeled with the short lived positron emitting nuclide C-11.
Carbon Radioisotopes↗
Effect of sterol biosynthesis inhibitor, SSF-109, on cholesterol synthesis in isolated rat hepatocytes.
The inhibitory effect of SSF-109 on cholesterol synthesis in isolated hepatocytes was studied using a radio-high-performance liquid chromatography system, and the results were compared with those of other inhibitors, triparanol and AMO-1618. SSF-109 caused accumulation of two trimethylsterols: lanosterol and 24-dihydrolanosterol. The distribution profile of [2-14C]mevalonate-originated radioactivity in cholesterol, lanosterol, dihydrolanosterol, 2,3-oxidosqualene, and squalene indicates that SSF-109 inhibits the 14 alpha-methyl demethylase activity. Triparanol accumulated the radioactivity of [2-14C]mevalonate in desmosterol and 2,3-oxidosqualene suggesting that triparanol inhibits sterol delta 24-reductase and 2,3-oxidosqualene cyclase. AMO-1618 caused enrichment of the radioisotope from [2-14C]mevalonate in 2,3-oxidosqualene but reduced it in squalene, suggesting that AMO-1618 acts on 2,3-oxidosqualene cyclase and some enzyme that catalizes a metabolic pathway between mevalonate and squalene.
Animals↗
Improved detection of antibodies to hepatitis C virus by the second-generation assay in patients with chronic non-A, non-B liver disease.
Serum samples from 337 Japanese patients with chronic non-A, non-B liver disease were tested for antibodies to hepatitis C virus (HCV) by means of first-generation (c100-3; anti-c100) and second-generation (pHCV-34, pHCV-31, c100-3; anti-HCV II) enzyme linked immunosorbent assays (ELISA) and for antibody to the GOR epitope (anti-GOR) also by ELISA. Anti-HCV II was detected in 314 (93.2%), anti-c100 in 247 (81.3%) and anti-GOR in 211 (62.6%) samples. Thus, anti-HCV II was more sensitive in detecting HCV infection than either anti-c100 or anti-GOR (P < 0.001). All serum samples reactive with anti-c100 or anti-GOR reacted with anti-HCV II. Among 314 anti-HCV II-positive patients, we found that 185 (58.9%) were positive for both anti-c100 and anti-GOR while 14 (4.5%) were positive for anti-HCV II alone. Nine (64.3%) of the 14 are presently infected with HCV, as revealed by detection of HCV RNA in their serum; the remaining five may have been infected in the past with HCV. These findings indicate that HCV is a major causative agent of chronic non-A, non-B liver disease in Japan and that detection of anti-HCV II is a specific and more sensitive diagnostic test for HCV infection.
Adult↗