Biomedical subjects

T Iwama

Publications and source records attributed to T Iwama.

At least 145 records · Page 8Linked to original sources

PubMed1992

The effect of three novel thromboxane A2 receptor antagonists (S-1452, AA-2414 and ONO-3708) on the increase in pulmonary pressure caused by Forssman anaphylaxis in guinea-pigs.

The effects were studied of three novel thromboxane A2 (TXA2) receptor antagonists (S-1452, AA-2414 and ONO-3708) on the increase in pulmonary pressure caused by Forssman anaphylaxis in guinea-pigs. Three TXA2 antagonists at doses of between 1 and 10 mg/kg administered orally 1 h before the challenge clearly inhibited the pulmonary pressure increase. At a dose of 10 mg/kg, all three antagonists inhibited the pulmonary pressure increase caused by leukotriene D4 (LTD4) and U-46619, but not that caused by histamine. The decrease in peripheral platelet counts caused by Forssman anaphylaxis was also clearly inhibited by the three TXA2 antagonists. However, the decreased peripheral leukocyte counts were unaffected by the three agents. The decrease in serum complement activity (CH50) was inhibited by S-1452 and AA-2414 at a dose of 10 mg/kg. In bronchoalveolar lavage fluid (BALF), significant increases in eosinophils and neutrophils were observed after Forssman anaphylaxis. Three TXA2 antagonists at a dose of 10 mg/kg (except for AA-2414 on eosinophils) did not affect the changes of leukocyte counts in BALF. Moreover, increases in the TXB2 and 6-keto-PGF1 alpha levels of the BALF brought about by Forssman anaphylaxis were unaffected by the three TXA2 receptor antagonists. Histamine and LTD4 were not changed in the BALF after Forssman anaphylaxis. These results indicate the efficacy of TXA2 receptor antagonists on the increase in pulmonary pressure caused by Forssman anaphylaxis in guinea-pigs by direct antagonism to released TXA2.

6-Ketoprostaglandin F1 alpha↗

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

Effects of carcinogenesis on colonic thymidine kinase activity in familial adenomatous polyposis.

Thymidine kinase (TK) activity of polyp tissue from patients with familial adenomatous polyposis (FAP) was measured and compared with that of non-tumorous colon, sporadic polyp and colorectal carcinoma tissues. Total TK activity in colonic carcinoma was 3-fold that of non-tumorous colon; its increase seems attributable mainly to increased activity of cytosolic TK isozyme activity. By using DEAE-cellulose column chromatography, the colorectal TK isozymes were separated into two types, i.e. two isozymes, referred to as the fetal (predominantly cytosolic) and adult (predominantly mitochondrial) types. However, FAP polyp samples from 15 patients showed an average elevation of only 1.8-fold over non-tumorous region of colon. Examined individually, only 5 of the 15 FAP samples showed significant elevations in total TK activity. Furthermore, TK isozyme analysis revealed variable patterns of the cytosolic isozyme activity, which was elevated in some cases (8/15) and remained low in others. Thus FAP polyps seem to be a heterogeneous population with respect to DNA replicative activity, and cytosolic TK isozyme activity may constitute a biochemical marker for the subsequent development of colorectal carcinoma in FAP.

Adenomatous Polyposis Coli↗

PubMed1992

Effect of murine recombinant interleukin-5 on the cell population in guinea-pig airways.

1. An intratracheal injection of murine recombinant interleukin 5 (mrIL-5, 2-15 microgram/0.25 ml/animal) induced a dose-dependent increase in the number of macrophages, eosinophils, neutrophils and epithelial cells in the bronchoalveolar lavage fluid (BALF) of guinea-pigs 24 h after administration. Bovine serum albumin (15 micrograms/0.25 ml/animal), used as a reference material, did not cause any change of this type. 2. The intratracheal administration of mrIL-5 at a dose of 15 microgram showed a tendency to increase the number of these pulmonary inflammatory cells and epithelial cells in the BALF at 12 h with a significant increase observed at 24 h. 3. Prednisolone (20 mg kg-1, i.p.) inhibited the mrIL-5-induced increase in macrophages, eosinophils, neutrophils and epithelial cells. Ketotifen (2 mg kg-1, i.p.) reduced the mrIL-5-induced increase in the eosinophil, neutrophil and epithelial cell populations. The simultaneous injection of 2% disodium cromoglycate (DSCG) into the trachea prevented the mrIL-5-induced increase in the number of airway epithelial cells, without affecting changes in the other inflammatory leukocytes. 4. These results suggest that mrIL-5 is a potent inducer of lung inflammation, in terms of increased inflammatory leukocytes and epithelial cells in guinea-pig BALF. Prednisolone, DSCG and ketotifen are effective against mrIL-5-induced pulmonary inflammation, especially the desquamation of bronchial epithelial cells.

Animals↗

PubMed1992

Inhibitory effect of NZ-107 on anaphylactic bronchoconstriction in guinea pigs and rats.

We studied the effect of NZ-107 in a number of animal models of anaphylactic bronchoconstriction. In conscious guinea pigs, pretreated with indomethacin, pyrilamine and propranolol, passively sensitized with heterologous anti serum, NZ-107 in doses of 10-30 mg/kg per os inhibited the aerosolized antigen-induced cough and collapse. NZ-107 in a high dose of 100 mg/kg per os significantly prevented aerosolized antigen-induced anaphylactic collapse, but not cough in actively or passively sensitized conscious guinea pigs and also significantly protected aerosolized histamine-induced collapse, but not cough in conscious guinea pigs. This compound had little inhibitory effect on aerosolized acetylcholine-induced cough and collapse. In anesthetized animals, the effect of NZ-107 on bronchoconstriction induced by intravenous administration of antigen and various agonists was examined by the method of Konzett and Rössler. In doses of 10-50 mg/kg per os, NZ-107 inhibited antigen-induced bronchoconstriction in anesthetized guinea pigs. NZ-107 when intravenously administered to the anesthetized guinea pigs inhibited not only leukotriene D4-induced bronchoconstriction, but also thromboxane A2 mimetic U-46619-, platelet-activating factor- and histamine-induced bronchoconstriction. In anesthetized rats, NZ-107 in a dose of 300 mg/kg per os tended to inhibit the antigen-induced bronchoconstriction, but this effect was not significant. These results indicate that NZ-107 acts as a spasmolytic agent which inhibits bronchial responses to antigens or various other bronchoconstrictors in animal models, suggesting that NZ-107 may be potentially beneficial in the treatment of bronchial asthma.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1992

Effects of NZ-107 on bronchoconstriction in guinea pigs.

The effect of 4-bromo-5-(3-ethoxy-4-methoxybenzylamino)-3(2H)-pyridazinone (NZ-107) on bronchoconstriction in guinea pigs was studied (1). The antigen-induced bronchoconstriction was studied in guinea pigs which had been passively sensitized by intravenous injection of antiserum containing anti-benzylpenicilloyl bovine-gamma-globulin IgE antibody. The sensitized guinea pigs were divided into two groups; one group was pretreated with metyrapone (11 beta-hydroxylase inhibitor in glucocorticoid metabolism) and the other with saline. The antigen-induced bronchoconstriction in the metyrapone-treated animals was more severe than that in the saline-treated animals. The asthmatic respiratory changes, in terms of prolongation of the ratio between expiration and inspiration, was also dramatically increased. NZ-107 at doses of 25 and 50 mg/kg significantly inhibited antigen-induced bronchoconstriction in both the saline-and metyrapone-treated animals. NZ-107 showed a tendency to inhibit accelerated severe asthmatic respiration more strongly in metyrapone-treated animals than in those treated with saline. Salbutamol inhibited antigen-induced bronchoconstriction in saline-treated animals, but its efficacy decreased in metyrapone-treated animals. Unlike salbutamol, prednisolone and hydrocortisone showed the reverse effect, inhibiting bronchoconstriction in metyrapone-but not in saline-treated animals. Sodium cromoglycate inhibited antigen-induced bronchoconstriction in both saline- and metyrapone-treated animals (2). When a subthreshold dose of platelet-activating factor was injected into guinea pigs, airway responsiveness against histamine was clearly increased. NZ-107 at a dose of 0.2 mg/kg i.v. inhibited PAF-induced airway hyperreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Albuterol↗

PubMed1992

Effect of NZ-107, a newly synthesized pyridazinone derivative, on antigen-induced contraction of human bronchial strips and histamine release from human lung fragments or leukocytes.

The effects of a newly synthesized pyridazinone derivative, NZ-107, 4-bromo-5-(3-ethoxy-4-methoxybenzylamino)-3(2H)-pyridazinone, and two well-known antiasthmatic drugs, amlexanox (orally active disodium cromoglycate-like drug) and disodium cromoglycate (DSCG) on antigen-, histamine- and leukotriene C4 (LTC4)-induced constriction of isolated human tracheal muscle, and histamine release from human lung tissues and leukocytes were investigated in vitro. In some experiments, salbutamol was used as a reference drug. NZ-107 inhibited antigen-, histamine- and LTC4-induced contraction of tracheal muscle. Amlexanox and DSCG did not affect the contractile response of tracheal muscle caused by each stimulant. Salbutamol inhibited antigen-induced contraction of tracheal muscle. NZ-107, amlexanox, DSCG and salbutamol clearly inhibited the antigen-induced release of histamine and LTC4 from human lung tissue. The antigen-induced histamine release from atopic human leukocytes was inhibited by NZ-107 and amlexanox, but not by DSCG. Pretreatment with IL-3 did not alter antigen-induced contraction of tracheal muscle and histamine release from lung tissue, but antigen- or calcium ionophore A 23187-induced histamine release from leukocytes was clearly enhanced. Amlexanox inhibited the IL-3-induced enhancement of histamine release from leukocytes in the case of both stimuli, but NZ-107 and DSCG had no effect. These data suggest that NZ-107 has potent anti-allergic actions based on the inhibition of antigen-induced contraction of human tracheal muscle and mediator release from human lung tissue and leukocytes.

Aminopyridines↗

PubMed1992

Synthesis and glutamate-agonistic activity of (S)-2-amino-3-(2,5-dihydro-5-oxo-3-isoxazolyl)-propanoic acid derivatives.

(S)-2-Amino-3-(2,5-dihydro-5-oxo-3-isoxazolyl)propanoic acid, (3a) and its analogs (3b--h) were prepared and evaluated for glutamate receptor-agonistic and antifungal activities. Several (S)- and (R)-2-amino-3-isoxazolylpropanoic acid derivatives (3a--d) were synthesized starting with (S)- and (R)-N-tert-butoxycarbonyaspartic acid alpha-methyl esters (4, n = 1) by means of Masamune's chain extension reaction followed by isoxazolone formation with hydroxylamine and subsequent deprotection reactions. Furthermore, (S)- and (R)-N-tert-butoxycarbonylglutamic acid alpha-methyl esters (4, n = 2) were converted to (S)- and (R)-2-amino-4-isoxazolylbutyric acid derivatives (3e-h) via the same sequence of reactions.

Antifungal Agents↗

PubMed1992

Reversing effect of anti-asthmatic drugs on bronchoconstriction induced by antigen challenge and histamine in anesthetized guinea pigs.

We performed an in vivo evaluation of bronchodilation using a model of antigen-induced bronchoconstriction in anesthetized guinea pigs pretreated with indomethacin, pyrilamine and propranolol, and the results were compared with those for the histamine-induced response. Test drugs were administered intravenously when the antigen or histamine response reached its peak. Leukotriene (LT) D4 antagonists, FPL55712 and LY171883, gradually reduced the antigen-induced response, whereas the lipoxygenase inhibitor phenidone had no such effect. The bronchodilator theophylline rapidly reduced the antigen-induced response, and the adenylate cyclase activator forskolin had a similar effect. The following drugs also had no effect: nifedipine (calcium-channel antagonist), cromakalim (potassium-channel opener), amlexanox and disodium cromoglycate: DSCG (anti-allergic drugs), OKY-046 (thromboxane A2 synthetase inhibitor), and dapsone (anti-inflammatory drug). Theophylline, the beta-adrenoceptor agonist salbutamol and the histamine H1-blocker pyrilamine had only a small reversing effect on histamine-induced bronchoconstriction. These results suggest that antigen-, but not histamine-, induced bronchoconstriction in anesthetized guinea pigs is a useful in vivo model for evaluating the bronchodilating effect of anti-asthmatic drugs.

Animals↗

PubMed1992

Overall clinical effect of percutaneous coronary angioplasty: a critical analysis by follow-up and long-term angiography.

In order to determine the clinical efficacy of coronary angioplasty, the outcome was analyzed in 557 patients who underwent initial angioplasty prior to the end of 1987. Primary success (reduction of stenosis greater than or equal to 20% and residual stenosis less than 50%) was achieved in 492 (88.3%) of the patients. Follow-up angiography showed patency (stenosis less than or equal to 50%) in 295 or 60.0% of the 471 patients and ultimate lesion patency was achieved by repeating angioplasty up to 4 times in 425 (91.4%) of 465 patients followed angiographically. At the 3-year angiography performed in 209 patients with patent lesions, only 2 patients exhibited progression of their disease at dilated sites, while 48 had new lesions. Taking into consideration the 55 patients with unsuccessful primary angioplasty, 10 patients with major complications and 9 patients with mild restenosis, 434 out of 530, or 81.9% of the patients appear to have benefited from angioplasty.

Adult↗

PubMed1992

Brain tumors manifesting as intracranial hemorrhage.

The clinical course and computed tomographic (CT) findings of 23 patients with brain tumors manifesting as tumoral hemorrhage were reviewed. The most common symptoms were headache and clouding of consciousness. A CT finding of a lesion located next to a solid or irregular clot indicated intratumoral hemorrhage. Precontrast CT demonstrating an indent on the hematoma surface was a valuable indicator of tumoral hemorrhage. A CT finding of accumulated levels of blood/fluid or a hyperdense mass containing small hematoma indicated intratumoral hemorrhage, and obscure hyperdensity indicated intratumoral hemorrhagic infarction. Such findings were often difficult to distinguish from spontaneous intracerebral hemorrhage due to other factors. The incidence of rebleeding from residual tumors was high, carrying a very poor prognosis, so radical removal of brain tumors with hemorrhage is very important.

Adolescent↗

PubMed1992

[Effect of denopamine on residual left ventricular dysfunction after complete revascularization].

Denopamine (15 mg/day) was administered to 20 patients with residual left ventricular dysfunction after successful percutaneous transluminal coronary angioplasty (75% or more diameter stenosis). Echocardiography was performed before and 6 months after denopamine administration to analyze the left ventricular function. There were significant decreases in both end-diastolic and end-systolic dimensions from 58 +/- 8.3 to 54 +/- 8.4 mm (p = 0.001), and from 44 +/- 10.1 to 40 +/- 10.3 mm (p = 0.005)), respectively, while % fractional shortening remained nearly constant (from 25 +/- 8.3 to 27 +/- 9.6%). Thus, denopamine improved the left ventricular function by decreasing left ventricular size while maintaining wall contractility.

Adrenergic beta-Agonists↗

PubMed1992

[An experimental study on portal infusion of 5-fluorouracil (the second report)].

This study was conducted to clarify the role of continuous portal infusion with 5-fluorouracil (FU) from two different standpoints. Experiment I (Assessment of the ability to reduce hepatic metastasis): Male Donryu rats (180-210 g) receiving intraportal inoculation of ascites hepatoma AH 60 C (4 x 10(6) cells) were divided into 3 groups; portal infusion group, venous infusion group and control. 5-FU (20 mg/kg/day) was continuously infused via either the portal vein or the femoral vein with heparin (100 U/kg/day) for 5 consecutive days. The portal infusion group alone showed a significant decrease in hepatic tumor volume on day 21 and prolonged survival time. Experiment II (Evaluation of the immunological effects): Animals without inoculation of AH 60 C were also randomized in the same way as Experiment I. There were no statistical differences among the 3 groups in total leukocyte counts, lymphocyte subpopulations or NK activities in the spleen, whereas hepatic NK activity was significantly decreased in the portal infusion group. Continuous portal infusion with 5-FU is considered effective to prevent lodging of tumor cells in the intra-hepatic portal system but might be disadvantageous for hepatic cellular immunity.

Animals↗

PubMed1992

[Familial cavernous angioma of the central nervous system--report of a family and review of literature].

In this paper we reported a familially occurred cavernous angiomas (CA) of the central nervous system (CNS). Case 1 was a 14-year-old female with an initial symptom of transient motor and sensory disorders of the right upper extremity. On examination she had a cutaneous angioma and no neurological deficit. CT and MRI revealed two lesions in the brain. These lesions were removed surgically and were diagnosed histologically as CA. Case 2 was a 45-year-old female, the mother of case 1, with a long standing headache. She had a cutaneous angioma and no neurological deficit. CT and MRI revealed a CA in the brain and a one in the cervical cord. Case 3 was an 11-year-old female, the cousin of case 1, with an initial symptom of left hemiparesis. On examination, she had a cutaneous angioma and left hemiparesis. CT revealed two lesions in the brain. These lesions were removed surgically and were diagnosed histologically as CA. Familial CA of the CNS is relatively rare and the reported cases were 24 families consisted of 70 cases. We analyzed the reported cases to clarify the specificities of the familial cases. In the familial cases, CAs were apt to be multiple and were located more frequently in the posterior fossa than in the non-familial cases. In some familial cases, the vascular anomalies of the CNS other than CA or CA of the skin or retina were also revealed. Because of high incidence (89%) of the hemorrhage from the histologically verified CA, operation should be carried out even in the cases of CA with mild or no symptom, if the lesion is accessible surgically.

Adolescent↗

PubMed1991

Effect of NZ-107 on late-phase airway responses and airway hyperreactivity in guinea pigs.

The effect of NZ-107 (4-bromo-5-(3-ethoxy-4-methoxybenzylamino)-3(2H)-pyridazinone) on late-phase airway responses and airway hyperreactivity was investigated in the guinea pig. Challenge with inhaled ovalbumin in conscious guinea pigs actively sensitized with inhaled ovalbumin caused triphasic bronchial obstruction, which peaked at 5-30 min, 6-8 h and 24 h. In this model, airway hyperreactivity to acetylcholine was observed 48 h after antigen challenge. Orally administered NZ-107, given 2 h before ovalbumin challenge significantly inhibited airway responses at 5-30 min (10 mg/kg), 6-8 h (30 mg/kg), 24 h (10 mg/kg) and airway hyperreactivity (30 mg/kg). When NZ-107 (10 mg/kg) was orally administered to the guinea pigs 3 h after ovalbumin challenge, it also inhibited airway responses at 6-8 h and 24 h and airway hyperreactivity. In anaesthetized guinea pigs, intravenous administration of NZ-107 (0.03-1.0 mg/kg) inhibited platelet-activating factor (PAF)- and propranolol-induced airway hyperreactivity to histamine. These results suggest that NZ-107 may be a useful drug for the treatment of bronchial asthma by reducing late-phase airway responses and airway hyperreactivity.

Aerosols↗

PubMed1991

p53 gene mutations in colorectal tumors from patients with familial polyposis coli.

The p53 gene has been elucidated as a tumor suppressor gene, and inactivation of this gene caused by deletion or point mutations may play a crucial role in the development of human malignancies. In colorectal carcinomas with an allelic deletion of the p53 gene, the remaining p53 gene was mutated with considerable frequency. It is most difficult to detect point mutations or small deletions of the gene because the mutations occur in diverse regions, although four hot spots have been observed [J.M. Nigro et al., Nature (Lond.), 342: 705-708, 1989]. The polymerase chain reaction and denaturing gradient gel electrophoresis facilitate detection of mutations in the hot spots of the p53 gene. Using these methods, we detected mutations in three adenomatous polyps and one carcinoma from familial polyposis coli patients and three carcinomas of sporadic cases. The DNA sequence analysis confirmed mutations of the p53 gene in 2 adenomas (13 base-pair deletions in one and a point mutation in the other) and 1 carcinoma (point mutation) from familial polyposis coli patients. These results suggest that the p53 gene mutations may be involved in the formation not only of carcinomas but also of adenomas which occur in familial polyposis coli patients.

Adenomatous Polyposis Coli↗

PubMed1991

A novel glutamate agonist, TAN-950 A, isolated from streptomycetes.

A novel antifungal amino acid antibiotic, TAN-950 A ([S]-2-amino-3-(2,5-dihydro-5-oxo-4-isoxazolyl)propanoic acid), was found to have affinity for three excitatory amino acid (EAA) receptors and to inhibit [3H]alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid ([3H]AMPA), [3H]kainate and [3H]3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid ([3H]CPP) binding competitively. It caused excitation of rat hippocampal CA1 neurons in vitro, an effect that was antagonized by an AMPA/kainate antagonist, 6,7-dinitroquinoxaline-2,3-dione (DNQX). Chemical modification of TAN-950 A brought about a large change in its pharmacological activity. Alkylation at the C-3 position of the isoxazolone ring markedly increased the ability to elicite neuronal firing. This agonistic effect was also antagonized by DNQX. The (R) enantiomer of TAN-950 A had increased selectivity for the N-methyl-D-aspartate (NMDA) receptor subtype. This selectivity was further enhanced by removal of the methylene group from the amino acid moiety. The most potent NMDA agonistic activity was observed with [R]-2-amino-2-(2,5-dihydro-3-methyl-5-oxo-4-isoxazolyl)acetic acid. These derivatives of TAN-950 A might be useful agents for investigating the pharmacological and physiological roles of EAA receptors.

Animals↗

PubMed1991

Left ventricular function during transient coronary occlusion: digital subtraction left ventriculograms during coronary angioplasty.

The impact of transient myocardial ischemia on left ventricular function was examined by digital subtraction left ventricular angiography. Contrast medium was injected into the right pulmonary artery before, at 60 seconds of balloon inflation, and 10 minutes after balloon deflation. A total of 69 patients completed the study. In 52 patients, the left anterior descending artery (LAD) was involved, and in 17, the right coronary artery (RCA) was the focus. Ejection fraction (EF) declined by balloon inflation and returned to baseline value after deflation of the balloon. There was tendency toward a lower EF and wider akinetic area for LAD dilatation. The linear correlation between resting EF and EF during balloon inflation suggested that the effect of momentary coronary occlusion on left ventricular function appears to be additive to pre-existing left ventricular dysfunction, and resting ejection fraction is an important parameter for estimating the degree of diminished left ventricular function during myocardial ischemia.

Angiography, Digital Subtraction↗