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Biomedical subjects

S Imai

Publications and source records attributed to S Imai.

At least 487 records · Page 27Linked to original sources
PubMed1989

Resistance of STS/A mice to lymphoma induction by X-irradiation.

While fractionated X-irradiation induced a high incidence lymphomas in BALB/cHeA mice (77% in females and 86% in males), it induced the disease at an extremely low incidence in STS/A mice (8% in females and 9% in males). The latent period of lymphoma development was short in BALB/cHeA mice, but relatively long in STS/A mice. No significant difference of incidence of the disease between sexes in either strain was observed. F1 hybrid mice showed an intermediate incidence of radiation-induced lymphomas. This suggests that neither resistance of STS/A mice nor susceptibility of BALB/cHeA mice to radiogenic lymphomas is dominant.

Animals↗
PubMed1989

[Anti-tumor effect of fluoropyrimidines on human tumor cell lines transplanted in nude mice with CCl4-induced liver dysfunction].

Tegafur (FT) is a masked compound of 5-fluorouracil (5-FU) and supposed to be activated in the liver. The present study was designed to estimate anti-tumor effect of FT on human tumors transplanted in nude mice with liver dysfunction induced by CCl4. Histologically, cirrhotic changes of liver were observed after injection with 1ml/kg 10% CCl4 twice a week for 8 weeks. Mice were transplanted with human gastric (GC-SF) or colonic cancer (CC-ZK) lines, and daily administered intragastrically with 5-FU (15mg/kg), FT (100mg/kg) or UFT (FT 20mg/kg + Uracil 44.8mg/kg) for 4 weeks. The growth of GC-SF was enhanced by liver dysfunction, but that of CC-ZK was not affected. The mean growth inhibition rates (MGIR) of CC-ZK by 5-FU, FT or UFT were 18.3, 33.1 and 54.2%, respectively, in mice without liver dysfunction, and 14.0, 50.0 and 59.5%, respectively, in mice with liver dysfunction. The MGIRs of GC-SF were 39.0, 63.8 and 48.0%, respectively, in mice without liver dysfunction, and 12.6, 53.6 and 50.0%, respectively, in mice with liver dysfunction. In both lines effect of 5-FU was reduced in liver dysfunction, but those of FT and UFT was not. These results suggest that FT and UFT can be used for cancer patients with liver dysfunction.

Animals↗
PubMed1989

Lymphocytes anticancer chemosensitivity testing in vitro--an approach to predict immunosuppressive effect of anticancer agents.

In an attempt to predict immunosuppression by chemotherapy, an in vitro lymphocytes chemosensitivity assay was developed. The effect of mitomycin C (MMC), carboquone (CQ), adriamycin (ADR) and 5-fluorouracil (5-FU) on spleen cells of BALB/c mice were assessed by phytohemagglutinin (PHA) response inhibition assay. ADR and 5-FU highly suppressed PHA response, whereas MMC or CQ had only a slight influence. The administration of ADR or 5-FU to mice resulted in a significant decrease of peripheral blood lymphocytes and cortical thymocytes in number, and pretreatment with ADR or 5-FU prior to tumor inoculation shortened the survival time of the mice. All these four agents highly suppressed in vitro DNA synthesis of MOPC-104E plasmacytoma, but ADR or 5-FU did not induce complete regression of the tumor. MMC or CQ induced complete regression of MOPC-104E, but they did not induce complete regression of the tumor transplanted in athymic nude mice. These results suggest that T cells participate in tumor regression and immunosuppression reduces antitumor activity of the host and that PHA response inhibition assay may be useful to predict immunosuppressive effect of anticancer agents.

Animals↗
PubMed1989

Alkylated cAMP derivatives: selective synthesis and biological activities.

Many alkylated cAMPs have been prepared and tested for their antitumor and cardiac activities. Treatment of cAMP with several bases and alkyl bromides gave alkyltriesters of cAMP (2), N6,N6,2'-O-trialkyl cAMPs (3), N6,2'-O-dialkyl cAMPs (4) and 2'-O-monoalkyl cAMPs (5) in one step. N6,N6-dialkyl cAMPs (6) were prepared from 2'-O-tosyl cAMP by the similar alkylation, followed by detosylation. Synthesis of N6-monoalkyl cAMPs (7) was achieved by the reductive alkylation of cAMP with aldehydes in one step. Alkyl triesters of cAMP exhibited antitumor activities against P815 cells. N6-mono and N6,N6-dialkyl cAMPs showed significant cardiac activities.

Alkylation↗
PubMed1989

Cardiohemodynamic effects of bopindolol in normotensive conscious dogs. A comparative study with pindolol.

Cardiohemodynamic effects and the beta-blocking action of a new beta-adrenoceptor blocking agent, bopindolol (Sandonorm) were compared with those of pindolol in conscious unrestrained dogs. The intravenous injection of pindolol (3-100 micrograms/kg) increased the heart rate and decreased the total peripheral resistance dose-dependently and markedly, while the same doses of bopindolol had no effect on the heart rate and decreased the total peripheral resistance only at the maximum dose (100 micrograms/kg). These changes were antagonized by propranolol (3 mg/kg). Isoprenaline (isoproterenol, 0.1 microgram/kg)-induced tachycardia was inhibited dose-dependently by both beta-blockers to similar degrees. While the decrease in the total peripheral resistance by isoprenaline was inhibited by pindolol dose-dependently, the inhibition by lower doses of bopindolol was not so marked; the inhibition became greater as the doses of bopindolol were increased. These results indicate that bopindolol is a beta 1-selective beta-blocker with an affinity to this subtype of the beta-adrenoceptor comparable to that of pindolol. Unlike pindolol, it exerted no partial agonist activity at the beta-adrenoceptor. Instead it produced the partial agonist activity at the beta 2-adrenoceptor at the highest dose tested.

Adrenergic beta-Antagonists↗
PubMed1989

Partial agonist activity of celiprolol as assessed in conscious unrestrained dogs in comparison with those of pindolol and labetalol.

The effects of celiprolol on the heart rate (HR) and the total peripheral resistance (TPR) were studied in chronically instrumented conscious dogs in comparison with those of pindolol, propranolol and labetalol. Intravenous injection of pindolol, celiprolol and labetalol increased the HR and decreased the TPR dose-dependently, whereas propranolol did not. The ratios of doses that elicited 12% changes in both parameters (HR12/TPR12) were 4.85 +/- 2.63, 0.61 +/- 0.03 and 0.42 +/- 0.11 for celiprolol, pindolol and labetalol, respectively, indicating the preferential reduction of TPR by celiprolol. Changes in HR and TPR produced by these three agents were antagonized by propranolol dose-dependently. However, inhibition by 3 mg/kg of propranolol was incomplete in the cases of labetalol-induced decrease in the TPR at the dose of TPR12 (51%) and celiprolol-induced increase in the HR at the dose of HR12 (89%). These results suggest that changes produced by celiprolol as well as pindolol and labetalol were mostly explainable by partial agonist activity via beta-adrenoceptors. However, the contribution of the alpha-blocking activity must also be taken into consideration in the case of the reduction of the TPR by labetalol. In addition, there is a possibility that celiprolol may increase HR via its direct action.

Adrenergic alpha-Agonists↗
PubMed1989

[Evaluation of the internal carotid artery blood flow velocity waveforms using continuous-wave Doppler ultrasound in pregnant women].

The internal carotid artery blood flow velocity waveforms were measured with continuous-wave Doppler ultrasound in 17 normal nonpregnant and 50 pregnant women. 1) The measurement of the blood flow velocities in the pregnant women revealed a characteristic pattern. That is, in the women in the early pregnant stage (less than 16 weeks' gestation, n = 13), the velocity was lower than that of nonpregnant women. In the middle pregnant stage (16 to 27 weeks' gestation, n = 18), the velocity became higher than in the early stage and in the late stage (equal to and more than 28 weeks' gestation, n = 19), it again became slower. 2) The initial systolic peak blood velocity (S1), end-diastolic blood velocity (d), time averaged maximal blood velocity (M), Pourcelot ratio (PR), systolic-diastolic ratio (S/D) and pulsatility index (PI) were calculated and did not show laterality in any group. 3) PR, S/D and PI of the women in the early stages of pregnancy were higher than those of nonpregnant women, indicating that the cerebral vascular resistance became higher in early pregnancy. This technique presented the possibility of the assessment of the cerebral blood circulation in pregnant women.

Adult↗
PubMed1989

[Effects of cardioplegic solutions on coronary artery and myocardium--comparison of the glucose-insulin-potassium solution and the St. Thomas' Hospital cardioplegic solution].

Effects of two cardioplegic solutions on coronary artery and myocardium were experimentally investigated in three types of preparations. In the isolated perfused guinea pig heart, infusion of Glucose-Insulin-Potassium (GIK) solution (37 degrees C) caused contraction of coronary artery, whereas the St. Thomas' Hospital cardioplegic solution (37 degrees C) produced vasodilation. At the end of 30 minutes reperfusion after continuous infusion of cardioplegic solution, the St. Thomas' Hospital cardioplegic solution produced a greater recovery of cardiac function than GIK solution. In the isolated pig coronary artery, vasoconstriction caused by high potassium content was diminished by addition of magnesium in concentration dependent manner. In the electrophysiological examination, the membrane potential of the guinea pig papillary muscle was recorded by means of conventional glass microelectrodes. Though GIK solution produced greater depolarization of resting membrane potential than the St. Thomas' Hospital cardioplegic solution, effects of the two different cardioplegic solution was not so different after reperfusion of Tyrode solution. The St. Thomas' Hospital cardioplegic solution resulted in greater recovery of contracting activity after reperfusion than GIK solution. These data suggest that GIK solution causes coronary vasoconstriction and has deleterious effects on myocardium and that the St. Thomas' Hospital cardioplegic solution has a vasodilating action and produced a greater myocardial protection than GIK solution.

Animals↗
PubMed1989

[Postoperative bronchopleural fistula--diagnostic significance of masked cases and results of early re-operation].

We studied recent-day cases of postoperative bronchopleural fistula from 1982 to 1985. And in 1985, postoperative chest X-ray films were intensively compared with previous ones. Radiological signs for bronchopleural fistula and/or alveolar fistula such as increases in air content and/or falls in air-fluid level of pleural space were seen in 11 (7.1%) of 155 pulmonary resection cases in 1985. Among them, 8 of these cases were confirmed as bronchopleural fistulas. So one half of cases with these radiological findings were bronchopleural fistulas. But 2 of these 8 cases were masked bronchopleural fistulas which were not recognizable by bronchofiberscope and soon or later, bronchopleural fistulas developed which were recognizable by bronchofiberscope. For differential diagnosis between the bronchopleural fistula and alveolar fistula, serial chest X-ray films which was compared with previous one, were useful. In masked bronchopleural fistula cases, abnormal findings as mentioned above were seen more than three times, but in alveolar fistula cases were seen less than two times. On the bronchoscopic examination, bronchopleural fistulas were mainly located at the side of the residual lobe on the stump. Bronchopleural fistula cases which were re-operated for re-amputation, re-suture, and coverage of the stump within 48 hours, were all cured. So we concluded early re-operation is the best choice for bronchopleural fistula patient, because of short administration, no cosmetical problems and no disadvantage for lung function.

Bronchial Fistula↗
PubMed1989

[Study of postoperative bronchopleural fistulas--analysis of factors related to bronchopleural fistulas].

Postoperative bronchopleural fistulas, although reduced in incidence, remain as a grave complication of pulmonary resection. In our department, cases of lung cancer have been rapidly increasing and those of infectious diseases have been decreasing. In light of this trend, the causes of bronchopleural fistulas may have changed, and thus we studied recent cases of postoperative bronchopleural fistulas from 1982 to 1986. Bronchopleural fistulas were seen in 5 (7.8%) of 64 cases of inflammatory diseases and in 19 (4%) of 481 cases of lung cancer. In lung cancer, bronchopleural fistulas were more frequently seen with advanced cases, especially in cases of residual tumors on the stump and in cases of intrathoracic use of anticancer drugs. The highest incidences of bronchopleural fistulas were seen with right pneumonectomy and right lower lobectomy. Bronchoscopic examination showed bronchopleural fistulas to be mainly located on the stump beside the residual lobe. When Sweet's procedure is employed, this is the point with the most tension on the stump. Clinical and retrospective analysis of preoperative data revealed the following factors to be significantly higher in cases of bronchopleural fistulas than in cases of non-bronchopleural fistulas: fever, use of steroid hormone, Haemophilus influenzae in sputum, elevation of erythrocyte sedimentation ratio and anemia. Such analysis of postoperative data showed the following factors to be significant: fever, use of steroid hormone, leucocytosis, tracheostomy and bronchoscopy for sputum suction.

Adolescent↗