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Biomedical subjects

M Miyamoto

Publications and source records attributed to M Miyamoto.

At least 289 records · Page 16Linked to original sources
PubMed1994

Effects of CS-905, a novel dihydropyridine calcium channel blocker, on arterial pressure, renal excretory function, and inner medullary blood flow in the rat.

CS-905 is a dihydropyridine calcium channel antagonist which stands out for its prolonged hypotensive effect, and which is currently under investigation for the treatment of hypertension. The aim of the current series of studies was to investigate the effects of CS-905 on renal function in relation to its effects on arterial pressure. In anesthetized spontaneously hypertensive rats (SHR), intravenous bolus injection of CS-905 reduced mean arterial pressure (MAP) in a dose-dependent fashion. In parallel, there was a dose-related increase in urine flow (V), sodium excretion (UNaV), renal plasma flow (RPF), and glomerular filtration rate (GFR). In chronically cannulated unanesthetized SHR, single-dose CS-905 by gavage produced a sustained reduction in MAP, a significant increase in V and UNaV, no effect on RPF, and an increase in GFR. Continuous intrarenal infusion of CS-905 in anesthetized normotensive Munich Wistar rats at doses that did not affect MAP caused a marked diuresis and natriuresis, without affecting RPF or GFR. To determine whether the diuretic and natriuretic effects of CS-905 were mediated by changes in inner medullary blood flow, the effect of CS-905 on vasa recta blood flow (Qvr) was studied by fluorescent videomicroscopy in anesthetized normotensive Munich Wistar rats during continuous intrarenal infusion. At low infusion rates, CS-905 was diuretic and natriuretic while increasing Qvr. With a high infusion rate, although the diuretic and natriuretic effects of CS-905 were maximal, Qvr decreased. These findings suggest that the diuretic and natriuretic effects of CS-905 are dissociated from and cannot be accounted for by changes in RPF, GRF, or Qvr, and are most likely secondary to a direct action of CS-905 on renal tubule handling of sodium and water.

Anesthesia↗
PubMed1994

[Clinicopathological features of dysembryoplastic neuroepithelial tumor (DNT): four cases report].

We reported four cases of dysembryoplastic neuroepithelial tumor (DNT) with intractable complex partial seizures, and analyzed their clinical and pathological features. The age of patients ranged from four to nineteen years old. Three were boys and one was a girl. The age of seizure onset ranged from eight months to five years. They did not have any neurological deficits. In all cases, CT scan revealed a low density mass in the temporal lobe. Two cases demonstrated calcifications, and another two cysts. The mass demonstrated low signal intensity in T-1 weighted MR images with mild contrast enhancement by Gd-DTPA. Long-term video-EEG monitoring revealed the epileptogenic focus in the temporal lobe on the side of the mass lesion. Anterior temporal lobectomy with total removal of the tumor was carried out in all cases. Hippocampectomy was performed in three cases in which intraoperative electrocorticogram demonstrated spike discharges in the hippocampus. In the surgical specimens, the tumor consisted of increased astrocytes, oligodendrocytes, and some neurons. A cortical nodule appeared in one case, and cortical dysplasia appeared in two cases. It was difficult to distinguish the tumor of case 3 from ganglioglioma because of mild neuronal atypia. The tumor of case 4 demonstrated increased capillary vessels and was also difficult to differentiate from vascular anomalies. The pathological diagnosis of DNT was still difficult. Consequently, we speculated that DNT included some transitional types between congenital anomalies and ganglioglioma.

Adolescent↗
PubMed1994

Biochemical properties of the major outer membrane proteins of Porphyromonas gingivalis.

The major outer membrane proteins (MOMP) of 53 and 67 kDa were identified by sodium dodecyl sulphate-polyacrylamide gel electrophoresis in outer membrane enriched fractions of Porphyromonas gingivalis FDC 381 and ATCC 33277, respectively. The MOMP were purified by anion exchange and gel filtration chromatography after extraction with Zwittergent 3-14. Their reactivity to monoclonal antibodies and their amino acid composition were analysed. The N-terminal amino acid sequences of twenty residues of both purified MOMP were determined and compared with those previously reported for MOMP of other periodontopathic bacteria.

Amino Acid Sequence↗
PubMed1994

[Anesthesia for the intraoperative electrocorticography of patients with uncontrollable epilepsy].

For the surgical treatment of uncontrollable epilepsy, it is essential to delineate the epileptogenic focus by the use of intraoperative electrocorticography. Most general anesthetic agents, however, suppress the epileptogenic focus. Therefore, such a patient is usually kept awake during the procedure using local anesthesia. We experienced 15 cases for these procedures. Anesthesia was induced with thiamylal and pancuronium was administered for tracheal intubation. Anesthesia was maintained with nitrous oxide, oxygen and enflurane or isoflurane. After the brain was exposed, volatile anesthetics were discontinued and replaced with intermittent fentanyl administration. Approximately 15 minutes before the start of intraoperative electrocorticography, nitrous oxide concentration was reduced to 30% or less. A resective epileptogenic focus was identified in every patients. In 2 patients, electrocorticographical focal seizure status was identified following the intraoperative electrocorticography. After the focus resection, seizure attacks were controlled only by the application of regular medical regimen in these patients. Low nitrous oxide and intermittent fentanyl administration can be recommended as a superior anesthesia technique for intraoperative electrocorticography.

Anesthesia, General↗
PubMed1993

Characterization of lung squamous cell carcinoma-derived T-cell suppressive factor.

BACKGROUND: The immunosuppressive state of a tumor-bearing patient is possibly mediated by tumor-derived factor. In this study, the authors characterized lung squamous cell carcinoma-derived immunosuppressive factor (LSCF). METHODS: The immunosuppressive activity of QG56 (a lung squamous carcinoma cell line)-derived LSCF was evaluated by the effect of culture supernatant of QG56 on anti-CD3 monoclonal antibody-induced T-cell, response such as proliferation (3H-thymidine uptake), cytotoxicity (51Cr-releasing assay), and expression of cytokine mRNA (polymerase chain reaction). The LSCF was partially purified with an ion-exchange high-performance liquid chromatography (HPLC) and a gel-filtration HPLC. RESULTS: The LSCF inhibited proliferation, cytotoxicity, and expression of cytokine mRNA of T-cells in a dose-dependent manner. It has a molecular weight of approximately 22 kd, and was sensitive to proteinase K, heating at 60 degrees C, and resistant to treatment with trypsin and pH 3 and 9. These properties appear to be similar to those of transforming growth factor-beta (TGF-beta). However, the activity of the LSCF was not abrogated by anti-TGF-beta sera, and the LSCF did not suppress the proliferation of TGF-beta-sensitive mink lung cells (Mv1Lu). CONCLUSIONS: These data suggest that LSCF may be a novel tumor-derived immunosuppressive protein factor.

Base Sequence↗
PubMed1993

Effects of sustained release formulation of thyrotropin-releasing hormone on learning impairments caused by scopolamine and AF64A in rodents.

The effects of a sustained-release formulation of thyrotropin-releasing hormone (TRH-SR) on learning impairments induced by scopolamine and a cholinergic neurotoxin, ethylcholine aziridinium ion (AF64A), were examined in rodents. Subcutaneous injection of TRH-SR (2.8 mg/kg as free TRH) produced a sustained increase in immunoreactive plasma TRH levels up to about 2 weeks after dosing in rats. TRH-SR (0.56 and 2.8 mg/kg) given subcutaneously 7 days before the acquisition trial markedly ameliorated scopolamine-induced amnesia in mice, as evaluated with a passive avoidance task. Repeated administration of TRH for 7 days at doses of 0.2-5 mg/kg s.c. elicited a dose-dependent recovery from amnesia induced by scopolamine, whereas only the group treated with 5 mg/kg/day showed a significant improvement. The rats with bilateral intracerebroventricular injection of AF64A (3.75 nmol/brain) showed a significant impairment in the water maze task 2 weeks after surgery. TRH-SR (0.56 and 2.8 mg/kg) also exhibited a dose-dependent ameliorating action on the deficit. These findings indicate that TRH-SR ameliorates learning impairments produced by scopolamine and AF64A, and suggest that continuous infusion of TRH may have a potent learning and memory improving action at low doses.

Amnesia↗
PubMed1993

High-level expression of the Japanese encephalitis virus E protein by recombinant vaccinia virus and enhancement of its extracellular release by the NS3 gene product.

Recombinant vaccinia viruses expressing the prM and E genes of the Japanese encephalitis virus (JEV) were constructed by use of synthetic promoters. While the recombinant virus mOJ6-SL, with an optimized vaccinia late-gene promoter, produced a 20-fold elevated level of E protein, as well as an 86-kDa precursor protein in infected cells, no significant quantitative difference was detected between the extracellular or cell-surface E protein produced by mOJ6-SL and those produced by mOJ6 with the 7.5-kDa promoter. However, when the cells were infected with Dengue 2 virus before infection with mOJ6-SL, the amount of the extracellular E protein increased 16-fold. In addition, enhancement of its extracellular release was observed when cells were co-infected with mOJ6-SL and recombinant vaccinia virus expressing the NS3 gene of JEV.

Amino Acid Sequence↗
PubMed1993

Upregulation of fibroblast growth factor-receptor messenger RNA expression in rat brain following transient forebrain ischemia.

Recently, we demonstrated that transient forebrain ischemia in rats leads to an early and strong induction of basic fibroblast growth factor (bFGF) synthesis in astrocytes in the injured brain regions. In this study, in order to clarify the targets of such raised endogenous bFGF levels, the messenger RNA (mRNA) expression of its receptors (flg and bek) in the hippocampus following transient forebrain ischemia induced by four-vessel occlusion for 20 min was investigated using an in situ hybridization technique. Transient forebrain ischemia induced an increase in the number of flg mRNA-positive cells from an early stage (24 h after ischemia) in the hippocampal CA1 subfield where delayed neuronal death occurred later (48-72 h after ischemia). This increase became more marked with the progression of neuronal death and was still evident in the same area 30 days later. The time course of the appearance and distribution pattern of flg mRNA-positive cells in the CA1 subfield were quite similar to those of bFGF mRNA-positive cells. On the other hand, in situ hybridization for bek mRNA showed only slight and transient (observed 72 h and 5 days after ischemia) increases in the number of mRNA-positive cells in the CA1 subfield following ischemia. The use of in situ hybridization and glial fibrillary acidic protein immunohistochemistry in combination demonstrated that the cells in the CA1 subfield that exhibited ischemia-induced flg or bek mRNA expression were astrocytes. These data indicate that transient forebrain ischemia induces upregulation of fibroblast growth factor-receptor expression, accompanied by increased bFGF expression in astrocytes, and suggest that the increased astrocytic bFGF levels in injured brain regions act on the astrocytes via autocrine systems and are involved in the development and maintenance of astrocytosis.

Animals↗
PubMed1993

Effect of trimebutine maleate on emptying of stomach and gallbladder and release of gut peptide following a solid meal in man.

We investigated the effect of orally administered trimebutine maleate on gastric and gallbladder emptying and on the release of gut peptide, pancreatic polypeptide (PP), and gastrin in humans for 120 min after ingestion of a solid meal. Gastric emptying was measured by a radionuclide technique. Gallbladder emptying was estimated by real-time ultrasonography. The oral administration of 200 mg of trimebutine maleate significantly shortened the lag time in starting gastric emptying (P < 0.05). Considering gallbladder emptying, trimebutine significantly inhibited the fasting emptying induced by neural reflex. Postprandially, there was a tendency toward an accelerated gallbladder emptying in the early phase. Neither the maximal percentage of gallbladder emptying nor the time of peak gallbladder emptying were affected. Trimebutine significantly blunted the post-prandial PP response in the cephalic and gastric phases, reflecting a vagal-cholinergic activity (P < 0.05). The PP response in the intestinal phase was also blunted. Gastrin release was significantly augmented only during the period of fasting after drug administration (P < 0.05). The major effect of trimebutine maleate appears to be a shortening of the lag time at the start of gastric emptying probably via its anticholinergic activity.

Administration, Oral↗
PubMed1993

Phenotypes of lymphocytes infiltrating non-small cell lung cancer tissues and its variation with histological types of cancer.

We investigated surface markers of lymphocytes infiltrating four different histological non-small cell lung cancer tissues obtained at surgery and the corresponding peripheral blood lymphocytes (PBL) of 40 clinical cases, who had undergone no prior anti-cancer treatment, by flowcytometry. In estimation of the mean proportion of each lymphocyte subset, a paired Wilcoxon test revealed that tumor-infiltrating lymphocytes (TIL) exhibited significantly higher values of CD3+ cells (P < 0.05), CD8+ cells (P < 0.05) and CD20+ cells (P < 0.01), and lower value of CD16+cells (P < 0.05), as compared with those in PBL. The Spearman test revealed that none of the values of surface markers in TIL statistically correlated with those in the corresponding PBL (r < 0.6, P > 0.05). Although there was no significant difference between the mean CD4/CD8 ratio of total TIL and that of PBL, TIL of 12 patients with squamous cell carcinoma almost always showed lower values of CD4/CD8 ratio than those in PBL (P < 0.05), while the CD4/CD8 ratio was similar between TIL and PBL in adenocarcinoma. These results suggest that TIL of lung cancers represent specific immunological responses, whose characteristic depend on the histological types of lung cancers.

CD4-CD8 Ratio↗