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Biomedical subjects

T Miura

Publications and source records attributed to T Miura.

At least 19 recordsLinked to original sources
PubMed1992

Leukotriene receptors in the skin of rats differ from those of mouse skin or rat stomach strip.

To compare the receptors for cysteinyl-leukotriene (cys-LT) in rat skin with those in other tissues, we investigated the effects of specific cys-LT receptor antagonists (FPL 55712, LY171883, MCI-826 and L-648051) on cys-LT-induced cutaneous reactions in rats and mice, and on cys-LT-induced contractile responses in rat stomach smooth muscle. We also studied the effects of these drugs on homologous passive cutaneous anaphylaxis. The four cys-LT receptor antagonists dose dependently inhibited cys-LT-induced cutaneous reactions in mouse ear, but failed to inhibit passive cutaneous anaphylaxis and the histamine-induced cutaneous reaction. In rats, only MCI-826 inhibited cys-LT-induced cutaneous reactions although the other three drugs failed to inhibit these reactions. In contrast, the cys-LT-induced contractile responses of rat stomach smooth muscle were inhibited by all these drugs in a concentration-dependent manner. These results suggest that cys-LT receptors in rat skin have an affinity different from that of receptors in mouse skin and rat stomach. They also suggest that cys-LTs are not involved in passive cutaneous anaphylaxis in mice and rats.

Acetophenones↗
PubMed1992

The role of hormones in the acquisition of sperm motility in salmonid fish.

In salmonid fish, spermatozoa taken from the testes are immotile, but acquire motility during their passage through the sperm duct. Using male masu salmon (Oncorhynchus masou), we found that gonadotropin-induced testicular production of 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (17 alpha, 20 beta-DP), the oocyte maturation-inducing hormone of salmonid fish, is responsible for the acquisition of sperm motility. However, neither testosterone (T) nor 11-ketotestosterone (11-KT), the two major androgens in teleost fish, were effective. We also present evidence that 17 alpha, 20 beta-DP action is mediated through an increase in sperm duct pH, which in turn increases the cAMP content of sperm allowing the acquisition of motility.

Animals↗
PubMed1992

Follow-up MRI in dural arteriovenous malformations involving the cavernous sinus: emphasis on detection of venous thrombosis.

Six patients with a dural arteriovenous malformation (dural AVM) involving the cavernous sinus were followed up with magnetic resonance imaging in order to assess change in the lesions. Spin-echo (SE) imaging of three patients in whom the AVM appeared to have closed at least 1 month earlier (two of them spontaneously, and one after external carotid artery embolization) showed neither apparent flow void in the involved cavernous sinus nor evidence of venous thrombosis. SE images of the other three patients who had not been cured by external carotid artery embolization (two of whom were examined within a week of treatment), detected persisting arteriovenous shunts, including high-flow cortical venous drainage, seen as flow void. Two-dimensional time-of-flight MR angiography (2D TOF MRA) was performed simultaneously in three patients. Whereas shunting blood and the normal cavernous sinus were of high intensity, presumed thrombosed cavernous sinuses were isointense with stationary brain tissue. SE imaging can confirm the resolution of arteriovenous shunts, but poorly delineates very acute and chronic thrombosis of the draining veins. In contrast, 2D TOF MRA directly demonstrates flowing blood, permitting the diagnosis of venous thrombosis; it should be included in follow-up of a dural AVM involving the cavernous sinus when venous thrombosis is suspected.

Adult↗
PubMed1992

Use of methotrexate, vinblastine, adriamycin, and cisplatin in combination with radiation and hyperthermia as neo-adjuvant therapy for bladder cancer.

In an attempt to improve the poor prognosis of invasive and/or high-grade bladder cancer after total cystectomy, we tried a combination of regional irradiation with hyperthermia (RH) therapy and systemic M-VAC (methotrexate, vinblastine, Adriamycin, and cisplatin) chemotherapy followed by surgery. The short-term results of these treatments were evaluated. A total of 17 patients received the combination of RH and M-VAC therapy between January 1989 and July 1990, and 12 then underwent total cystectomy. Of the 17 patients, 14 were evaluable for tumor response. The objective response rate was 64% (9/14), with 4 patients achieving a complete remission that was confirmed by histological examination. Nausea and vomiting were inevitable, and 71% (12/17) of the patients developed leukopenia. However, these side effects were not serious. Considering the previous results obtained using RH therapy in the absence of chemotherapy for this disease, no significant difference in the tumor response was detected between the RH only group and the RH plus M-VAC group. The long-term results cannot yet be evaluated, but we will continue to follow these patients in the future so as to clarify the usefulness of M-VAC therapy as preoperative therapy.

Adult↗
PubMed1992

The effect of prednisolone on substance P-induced vascular permeability in mice.

The effect of prednisolone on the substance P (SP)-induced vascular permeability increase in male ddY, WBB6 F1(-)+/+ (control) and WBB6 F1-W/WV (no mast cell in skin or internal organs) mice was investigated. 1) SP (1-10,000 pg/site) increased vascular permeability in ddY, WBB6 F1(-)+/+ and WBB6 F1-W/WV mice ears. 2) SP (100 pg/site)-induced vascular permeability was inhibited by prednisolone (10 mg/kg) administered intraperitoneally 3 to 12 hours prior to the elicitation of the reaction in ddY mice. When dexamethasone at a dose of 1 mg/kg was administered intraperitoneally 2 to 24 hours prior to the elicitation of the reaction, significant inhibition was observed. When prednisolone was administered intraperitoneally 8 hours prior to the elicitation of the reaction, the SP-induced capillary permeability increase in both ddY and WBB6 F1-W/WV mice was clearly inhibited by the drug at doses of 5 and 10 mg/kg. 3) Diphenhydramine (1 and 10 mg/kg) inhibited SP-induced vascular reaction in ddY mice but not in WBB6 F1-W/WV mice. 4) Atropine (10 mg/kg) inhibited SP-induced vascular reaction in both ddY and WBB6 F1-W/WV mice. But acetylcholine did not cause an increase of vascular permeability in ddY and WBB6 F1-W/WV mice ears. 5) Prednisolone (5 mg/kg) inhibited histamine- and serotonin-induced vascular permeability in ddY and WBB6 F1-W/WV mice ears. 6) Prednisolone (5 and 10 mg/kg) inhibited the SP-induced histamine release from ddY mice peritoneal mast cells. These results suggest that the vascular effect of SP is mediated by both mast cell dependent (release of histamine from mast cells) and mast cell independent mechanisms. Prednisolone inhibits the SP-induced vascular permeability mediated by both mechanisms in mice.

Animals↗
PubMed1992

Oxidative damage to bovine serum albumin induced by hydroxyl radical generating systems of xanthine oxidase + EDTA-Fe3+ and ascorbate + EDTA-Fe3+.

Oxidative damage to bovine serum albumin (BSA) was induced by hydroxyl radical (HO.) generating systems of xanthine oxidase (XO) + EDTA-Fe3+ and ascorbate + EDTA-Fe3+. Formation of bityrosine and loss of tryptophan were observed in the ascorbate + EDTA-Fe3+ system and carbonyl formation was induced by both systems. Mannitol and ethanol very strongly inhibited the carbonyl and/or bityrosine formation, indicating that the oxidative damage to BSA was due to HO(.). The sulfhydryl (SH) groups of BSA were very sensitive to the XO + EDTA-Fe3+ but not to the ascorbate + EDTA-Fe3+ system. Catalase but not hydroxyl radical scavengers or superoxide dismutase strongly inhibited the loss of SH groups, indicating that H2O2 is involved in their oxidation. Fragmentation of BSA was observed during exposure to the XO + EDTA-Fe3+ and ascorbate + EDTA-Fe3+ systems and the products presented a broad band on sodium dodecyl sulfate polyacrylamide gel electrophoresis. Little formation of amine groups was observed in these systems, indicating that little peptide bond cleavage occurred. BSA exposed to the ascorbate + EDTA-Fe3+ system was more readily degraded by trypsin than that exposed to the XO + EDTA-Fe3+ system. Elastase degraded BSA exposed to the ascorbate + EDTA-Fe3+ system but not to the XO + EDTA-Fe3+ system.

Amines↗
PubMed1992

Antiallergic mechanisms of beta-adrenergic stimulants in rats.

Antiallergic mechanisms of beta-adrenergic stimulants were investigated in rats. Isoproterenol administered intravenously inhibited IgE antibody-mediated homologous passive cutaneous anaphylaxis (PCA) and histamine-induced cutaneous reaction (HCR) elicited at the same time in the same rats significantly. The inhibition of PCA was more potent than that of HCR, suggesting that PCA is inhibited by at least 2 mechanisms. One is the inhibition of vascular permeability increase. In vivo histamine release in the rat peritoneal cavity caused by intravenous antigen was inhibited by the intravenous administration of isoproterenol or salbutamol dose-dependently. On the contrary, when the histamine release in the peritoneal cavity was caused by intraperitoneal antigen, isoproterenol or salbutamol administered simultaneously with antigen failed to inhibit the reaction. Furthermore, antigen-induced histamine release from sensitized peritoneal exudate cells in vitro was not inhibited by isoproterenol or salbutamol. These results indicate that the primary target of beta-adrenergic stimulants is the vascular endothelium, and that the direct inhibition of chemical mediator release from mast cells does not play an important role for the inhibition of PCA and in vivo histamine release in the peritoneal cavity in rats. Beta-adrenergic stimulants therefore may prevent intravenously administered antigen from activating sensitized mast cells through affecting endothelial cells.

Albuterol↗
PubMed1992

Cleft hand, syndactyly and hypoplastic thumb.

The clinical features of 58 patients with typical cleft hand were examined and compared with 86 patients with syndactyly between the long and ring fingers, 27 patients with syndactyly between the ring, little and other fingers, 53 patients with hypoplastic thumb and 100 patients with symbrachydactyly. The clinical findings of the typical cleft hand resembled those of syndactyly. There were two unusual cases of typical cleft hand associated with hypoplastic thumb, congenital heart anomalies and absence of the axial triradius. One of these also had cleft lip and palate. The critical embryonic period of the heart anomaly is early, while that of the cleft lip and palate is late. These findings suggest that an embryo with typical cleft hand and hypoplastic thumb results from impairments at two different times in the early embryonic period.

Abnormalities, Multiple↗
PubMed1992

The activity of dipeptidyl peptidase II and dipeptidyl peptidase IV in mice immunized with type II collagen.

We investigated the activity of peptidases in the serum of mice with experimental polyarthritis that was induced by the injection of type II collagen, an experimental model of human rheumatoid arthritis. The activity of dipeptidyl peptidase II (DPP II) was increased and that of dipeptidyl peptidase IV (DPP IV) was decreased resulting in the significant increase of the serum DPP II/DPP IV ratio in the polyarthritic mice compared with that of controls. These results indicate that the DPP II/DPP IV ratio is a novel index of disease activity in mice with collagen-induced polyarthritis and may be useful in assessing the activity of rheumatoid arthritis in humans.

Animals↗
PubMed1992

Effects of a newly synthesized leukotriene antagonist, NZ-107, on immediate-type hypersensitivity reaction in rats and guinea-pigs.

The effects of 4-bromo-5-(3-ethoxy-4-methoxybenzylamino)-3(2H)-pyridazinone (NZ-107) on immediate type hypersensitivity reactions in rats and guinea-pigs were studied. 1. When NZ-107, at a dose of 50 mg/kg (i.p.) or 100 mg/kg (orally), was administered to rats, 48-h homologous passive cutaneous anaphylaxis (PCA) reaction and histamine-, leukotriene C4 (LTC4)- and leukotriene D4 (LTD4)-induced skin reactions were suppressed by the agent. 2. NZ-107 (10(-6) g/ml) inhibited both LTC4- and LTD4-induced contractions of isolated rat stomach smooth muscle. 3. NZ-107 inhibited antigen-induced histamine release from rat peritoneal mast cells by 26% at a concentration of 10(-4) g/ml. 4. NZ-107, at doses of 25 and 50 mg/kg (orally), significantly inhibited guinea-pig 3-h heterologous PCA reaction. 5. NZ-107 inhibited antigen-induced histamine release from guinea-pig lung tissue by 17% and 48% at concentrations of 5 x 10(-5) and 10(-4) g/ml, respectively. 6. NZ-107, at doses of 25 and 50 mg/kg (i.p.), inhibited antigen-induced bronchoconstriction and eosinophil accumulation in the bronchoalveolar lavage fluid (BALF) of guinea-pigs. These results suggest that NZ-107 has anti-allergic action including inhibition of eosinophil accumulation in an antigen-challenged airway lesion in rats and guinea-pigs. The anti-allergic action of this agent is thought to be due to its action as a histamine and LT antagonist and its consequent inhibition of antigen-induced histamine release.

Animals↗
PubMed1992

Reperfusion injury in bone: effects of CV-3611, a free radical scavenger, on ischemic revascularized bone grafts in rats.

Oxygen-derived free radicals have been shown to play an important role in reperfusion injury. The protective effect of CV-3611, a new free radical scavenger, on reperfusion injury in an ischemic revascularized hind limb model in rats was examined. Warm ischemia (25 degrees C) was produced by vascular pedicle clamping and sustained for 0, 3, and 6 hr. Histologic and fluorochrome bone-labeling analyses demonstrated improved overall viability of osteocytes, osteoblasts, and marrow cells in the CV-3611-treated group compared to controls. The CV-3611-treated group had statistically significant improvement in the ratio of lacunae, maintained osteogenetic ability, and preserved normal growth plate architecture after 6 hr of ischemia. The control group showed local central areas of disorganization by 3 hr and complete destruction of the growth plate with early growth arrest after 6 hr of ischemia. These results indicate that administration of CV-3611 prior to reperfusion can prevent reperfusion damage in bone tissue and maintain osteogenetic ability. This technique may have clinical application for reducing the complications of prolonged ischemia to bone tissue.

Animals↗
PubMed1992

Enhancement of the force-frequency effect on myocardial contractility by adrenergic stimulation in conscious dogs.

BACKGROUND: The influence of changes in heart rate on myocardial contractility (the force-frequency effect) differs under various experimental conditions, including the anesthetized versus the conscious state. METHODS AND RESULTS: To assess the influence of beta-adrenergic stimulation on force-frequency effects on myocardial contraction and relaxation, seven instrumented conscious dogs were studied in which heart rate could be controlled by atrial pacing after the intrinsic rate was slowed with a bradycardiac agent (UL-FS 49 0.5-0.75 mg/kg). Left ventricular (LV) pressure was measured with a micromanometer under resting conditions and during dobutamine infusion at low, intermediate, and high doses (2.7, 5.4, and 10.7 micrograms/kg/min). At each dose, heart rate was progressively increased from 100 to 210 beats per minute. In the absence of dobutamine (control), no significant positive force-frequency effect was detected on LV dP/dtmax; this was probably due to the known effect of the observed decrease in preload to reduce LV dP/dtmax, thereby offsetting an effect of the force-frequency response to increased dP/dt. However, during dobutamine infusions, the force-frequency effect was observed to increase significantly in a dose-dependent manner with increases in heart rate. An increase in heart rate from 100 to 210 beats per minute increased LV dP/dtmax by 12.4 +/- 12.5% with low-dose, 22.7 +/- 13.1% with intermediate-dose, and 27.5 +/- 8.9% with high-dose dobutamine. Changes in preload and aortic pressure were within the same ranges under control conditions and at each of the three dobutamine doses. The time constant of LV pressure fall (tau) was significantly shorter with increases in heart rate during control, but only the highest dobutamine dose caused further significant shortening in tau with increased heart rate. CONCLUSIONS: These data indicate that there is a pronounced dose-dependent action of beta-adrenergic stimulation to enhance force-frequency-induced contractile responses in normal conscious dogs.

Adrenergic beta-Agonists↗
PubMed1992

Studies on the anti-allergic mechanism of glucocorticoids in mice.

Glucocorticoids inhibit IgE antibody-mediated passive cutaneous anaphylaxis (PCA) and chemical mediator-induced cutaneous reactions elicited in the mouse ear. In the present study, we investigated the effect of actinomycin D, a protein synthesis inhibitor, on dexamethasone-caused inhibition of PCA and histamine-induced cutaneous reaction in the mouse ear. Tyrosine aminotransferase (TAT) activity in the liver, which was estimated as an index for protein synthesis, significantly increased by the administration of hydrocortisone, prednisolone and dexamethasone. Significant increase in TAT activity was observed from 2 h after glucocorticoid administration and peaked at 4 h, and declined gradually thereafter. Cycloheximide even at high doses of 100 and 300 mg/kg failed to affect the increase in TAT activity by dexamethasone. On the contrary, actinomycin D at doses of 1 and 10 mg/kg abrogated the TAT activity increase by dexamethasone almost completely. Treatment with 1 mg/kg of actinomycin D, however, failed to affect the inhibition of PCA and histamine-induced cutaneous reaction by dexamethasone. These results suggest that glucocorticoids exhibit their inhibitory action of PCA and chemical mediator-induced cutaneous reactions in mice through a mechanism resistant to actinomycin D treatment.

Animals↗
PubMed1992

Mechanisms for glucocorticoid inhibition of immediate hypersensitivity reactions in rats.

The inhibitory mechanisms of immediate hypersensitivity reactions by glucocorticoid (GC) were studied in rats. Homologous passive cutaneous anaphylaxis (PCA) mediated by IgE antibodies and cutaneous reactions caused by histamine, serotonin and leukotriene C4 were elicited at the same time in the same rats. Three kinds of GC, hydrocortisone, prednisolone and dexamethasone, inhibited all these reactions significantly. Although mediator-induced cutaneous reactions were inhibited transiently around 2 hours after GC administration, inhibition of PCA was more potent and lasted longer. A time lag seemed to be essential for both inhibitions. IgE antibody-mediated histamine release in vivo in the rat peritoneal cavity was also inhibited by GC administration significantly, and the inhibition was long lasting when compared to those of the mediator-induced cutaneous reactions. Tyrosine amino-transferase (TAT) activity in the rat liver increased significantly by GC administration, and the increased TAT activity was completely abrogated by simultaneous administration of 5 mg/kg of cycloheximide (CH). In the same experimental condition, although inhibition of histamine-induced cutaneous reaction by GC was completely abrogated, the inhibition of PCA elicited at the same time in the same rats was only partially attenuated. Furthermore, the same dose of CH little affected the dexamethasone inhibition of histamine release in the rat peritoneal cavity, although the increase of TAT activity in the liver of the same rats was completely abrogated. These results demonstrate that PCA is inhibited by GC through at least 2 mechanisms, inhibition of mediator release from mast cells and non-specific inhibition of vascular permeability increase caused by released mediators. Although the latter action of GC is dependent upon protein synthesis, the former seems to be mediated by a unique mechanism independent of protein synthesis.

Animals↗
PubMed1992

Effect of anoxic preperfusion on ischemic myocardial injury in isolated rat hearts.

Anoxic perfusion prior to sustained ischemia (anoxic preperfusion), reportedly improves postischemic functional recovery of the heart, but its mechanism has not been well understood. The present study aimed to characterize the cardioprotective effects of anoxic preperfusion and its relationship to extracellular Ca++ levels. Following 10 min of aerobic perfusion, isolated rat hearts were assigned to a 10 min aerobic perfusion or to a 10 min anoxic perfusion. The hearts were then subjected to 30 min of global ischemia and 30 min of aerobic reperfusion. When the perfusate-free Ca++ concentration was 2.0 mM, postischemic recovery of left ventricular developed pressure was significantly improved by anoxic preperfusion (91.9 +/- 2.9% of baseline value vs. 50.5 +/- 12.9% after 30 min reperfusion in the controls). However, the improvement of postischemic ventricular function by anoxic preperfusion was abolished when perfusate Ca++ was reduced to 1.0 mM and the contractile function was rather suppressed during early reperfusion by anoxic preperfusion when the Ca++ level was 0.7 mM (87.5 +/- 11.8% vs. 115.6 +/- 13.9% after 10 min of reperfusion). On the other hand, lactate accumulation during the global ischemia was significantly less in anoxic preperfused hearts compared with untreated hearts both when perfusate Ca++ was 0.7 mM (61.3 +/- 5.1 vs. 85.9 +/- 6.8 mumol/g dry) and when it was 2.0 mM (43.8 +/- 2.0 vs. 140.3 +/- 14.1 mumol/g dry). The amount of myoglobin released after global ischemia was not different between untreated and anoxic preperfused hearts regardless of the perfusate Ca++ level. The results suggest that anoxic preperfusion does not reduce ischemic myocardial necrosis, but it attenuates myocardial stunning. That effect of anoxic preperfusion on the stunning is dependent on the extracellular Ca++ level and is not totally explained by suppression of ischemia-induced lactate accumulation.

Adenosine Triphosphate↗
PubMed1992

[Superficial and pedunculated signet ring cell carcinoma of the urinary bladder: a case report].

A case of primary signet ring cell carcinoma of the urinary bladder is described. A 63-year-old man presenting with difficulty of urination and miction pain had a pedunculated soybean-size tumor on the left lateral wall of the bladder. Specimens of the tumor were obtained by transurethral resection and the pathological diagnosis was signet ring cell carcinoma. There was no evidence of bladder metastasis from other organs. The patient then had intraoperative radiotherapy and he is alive without recurrence 20 months after the operation. We briefly discuss 73 cases of signet ring cell carcinoma of the urinary bladder collected from the English and Japanese literature. The tumor in this patient was the smallest of all cases reported previously.

Adenocarcinoma, Mucinous↗
PubMed1992

[Flower bud differentiation and development of opium poppy (Papaver somniferum L.) II. Effects of daylength and temperature].

We investigated the effect of daylength (from 9 to 15 hours) and cultivation temperature (from about 13 to 25 degrees C) on flower bud differentiation of three strains of Papaver somniferum L. cv. Ikkanshu, which have been cultivated in Nayoro (Hokkaido), Tsukuba (Central Honshu) and Nagasaki (Kyushu) for the last a few decades. 1. The experiment on the effect of daylength on flowering revealed that the longer the photoperiod was, the earlier flowering occurred. 2. Flower bud differentiation was observed at temperatures of 20 degrees C or less but never at 25 degrees C, and it was more quickly induced at lower temperatures. Furthermore, we also found that the optimum temperature for flower bud development following differentiation was 20 degrees C. From these findings, we reached the conclusion that this species has thermosensitivity. 3. Flower bud differentiation clearly occurred later in the Nayoro strain than in the Nagasaki strain or the Tsukuba strain. This seems to indicate that the Nayoro strain is a different ecological type from other strains. 4. When we compared the size and dry weight of the capsules, which are known to be closely related to opium yield, the capsules of the Nagasaki and Tsukuba strains were considerably smaller and lighter than those of the Nayoro strain. This is attributable to the fact that flower bud differentiation occurred at an early stage before the achievement of sufficient vegetative growth in the Nagasaki and Tsukuba strains.

Light↗