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Biomedical subjects

T Okamura

Publications and source records attributed to T Okamura.

At least 613 records · Page 34Linked to original sources
PubMed1988

Role of vascular angiotensin converting enzyme in hypertension.

The possible role of vascular angiotensin converting enzyme (ACE) in the maintenance of one-kidney, one clip (1-K,1C) hypertensive rats was studied in comparison with age-matched, one-kidney (1-K) normotensive rats. Mean blood pressure was elevated after partial occlusion of the left renal artery with unilateral nephrectomy, and the high blood pressure persisted for at least 11 weeks, whereas no significant changes in mean blood pressure were observed in 1-K rats. Plasma and vascular renin activities and plasma ACE activity did not differ between the two groups of rats, both 5 and 11 weeks after operation. In contrast, ACE activity in lung and mesenteric arteries in 1-K,1C hypertensive rats was significantly elevated 11 weeks after operation, but not 5 weeks after operation, compared with the matched 1-K normotensive rats. In addition, the decreases in mean blood pressure induced by ACE inhibition were significantly greater in 1-K,1C rats than those in 1-K rats. These results indicate that the elevation of vascular ACE activity may play an important role in the maintenance of high blood pressure and may result in hypotension in response to ACE inhibitors in the chronic stage of 1-K,1C hypertension.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1988

[Coronary artery blood flow velocity non-invasively measured using a vessel-tracking pulsed Doppler system].

A newly-developed noninvasive method was used to measure left coronary blood flow during phantom experiments. Two techniques were used in which: (1) the sample position can always be set in a fluctuating vessel using a wall echo-tracking method with a phase-locked-loop, and (2) the Doppler reference signal was generated separately synchronous with the wall echo signal. These techniques were combined, using a commercially available pulsed Doppler apparatus (SSH-40B: Toshiba). Basic experiments were performed using a blood vessel phantom to verify the validity of these systems. Blood flow velocity in the fluctuating tube could be measured clearly using a vessel-tracking method. The blood flow velocity of the left anterior descending artery was measured in three normal subjects and in seven patients from the third intercostal space along the left sternal border. The velocity pattern was characterized by a crescendo-decrescendo shape in diastole. The peak velocity which appeared in diastole ranged from 19 to 69 cm/sec, with no difference by disease entity. However, in all cases, the blood flow velocity signals were marred by extraneous signals, making it impossible to measure blood flow velocity during systole. Further improvement of the system is mandatory in order to use this flowmeter clinically.

Adult↗
PubMed1988

Endothelium-dependent and independent responses to prostaglandin H2 and arachidonic acid in isolated dog cerebral arteries.

The addition of prostaglandin (PG) H2 produced a transient contraction followed by a relaxation in helical strips of dog cerebral arteries partially contracted with PGF2 alpha or K+. The contraction was abolished by removal of endothelium, and the relaxation was potentiated. Relaxation induced by PGI2 was not influenced by endothelium denudation. The PGH2-induced contraction in strips with intact endothelium was not influenced by OKY-046, a thromboxane A2 synthesis inhibitor, but was abolished by treatment with ONO3708, an antagonist of vasoconstrictor PGs, whereas the relaxation was inhibited by tranylcypromine or diphloretin phosphate, a nonselective PG antagonist. Contraction induced by arachidonic acid (AA) was reversed to relaxation by removal of endothelium or treatment with ONO3708. Treatment with indomethacin attenuated the AA-induced contraction in the intact strips and also the relaxation in the strips treated with ONO3708 or denuded of endothelium. It may be concluded that vasoconstrictor PGs are synthesized from PGH2 or AA mainly in endothelium, and the production of PGI2 from PGH2 is not dependent on endothelium. Thromboxane A2 in concentrations sufficient to elicit significant contractions does not appear to be liberated from the cerebroarterial wall stimulated by PGH2.

Animals↗
PubMed1988

[Long-term chemotherapy in patients with stage IV gastric cancer after surgical treatment--a randomized comparative study of FT-207 and UFT].

A prospective randomized and comparative study of FT-207 and UFT was performed for cases of Stage IV gastric cancer involving long-term cancer chemotherapy after surgery. Immediately after the surgery, the subjects were randomly divided into two groups: A group treated by MMC and FT-207: and B group treated by MMC and UFT. From a total of 54 cases, 8 cases were excluded, so that A group consisted of 24 subjects and B group of 22 subjects. There were no differences in background factors between the two groups. In a comparison of all the cases, B group revealed a significantly higher survival rate than A group. These results indicated that the simultaneous use of MMC and UFT was effective as a long-term cancer chemotherapy after surgery for patients with Stage IV gastric cancer.

Adult↗
PubMed1988

[Effect of intrabladder instillation of various anticancer agents on carcinogenesis in rat bladder].

After administration of N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) to 6-week-old, female F344 rats, various anticancer agents and immunotherapeutic agents were injected into the bladder and their effects were investigated. Injection of adriamycin and mitomycin C (MMC) into the bladder a total of 12 times, 4 weeks after administration of BBN markedly promoted carcinogenesis of the bladder. Injection of bleomycin, cis-dichlorodiamine platinum (CDDP) and picibanil into the bladder a total of 12 times, 4 weeks after administration of BBN did not promote carcinogenesis and CDDP exhibited a tendency to inhibit carcinogenesis. Injection of MMC, CA (cytarabine) and MMC + CA into the bladder a total of 12 times, 4 weeks after administration of BBN indicated that CA has the potential to inhibit the bladder carcinogenesis-promoting effect of MMC. Injection of CDDP and MMC into the bladder a total of 12 times, 20 weeks after administration of BBN inhibited proliferation of bladder carcinoma. Additionally, administration each of CDDP and MMC alone exhibited a carcinogenic effect on the bladder. The above-described results show that considerable care should be taken and that long-term observation of course is required with the use of anticancer agents such as ADM and MMC.

Administration, Intravesical↗
PubMed1987

Different distribution of two types of angiotensin II-generating enzymes in the aortic wall.

Dog, monkey and human aortic tissues contained two distinct types of angiotensin II-generating enzymes; angiotensin converting enzyme (ACE) and chymostatin-sensitive angiotensin II-generating enzyme (CAGE). Endothelium, media and adventitia of canine thoracic aortae were separated using collagenase digestion, and determined for their ACE and CAGE activity. ACE activity was assayed by hippuryl-His-Leu cleavage. CAGE activity was estimated with ANG I as substrate in the presence of inhibitors of ACE and angiotensinases. His-Leu, the common product of both enzyme reactions, was fluorimetrically quantified after o-phthalaldehyde condensation. ACE localized mainly in endothelium, while CAGE distributed predominantly in adventitia. Similar results were obtained with human and monkey aortae. Such a contrasting distribution may indicate the distinct functional role of these two enzymes.

Aorta↗
PubMed1987

[Bone scintigraphy in bone metastases due to prostatic cancer].

Findings of bone scintigraphy with 99mTc-MDP were compared with bone radiography and biochemical data including total acid phosphatase (T. ACP), prostatic acid phosphatase (P. ACP), and alkaline phosphatase (ALP) in 35 patients with histologically proven prostatic cancer. Bone metastases were diagnosed in 20 of 35 cases (57%) by scintigraphy. The common sites of metastases were the pelvic bones, ribs, lumbar and thoracic vertebrae. In vertebrae, metastases were mainly distributed in the lower level. The most frequent radiographic change due to metastases was the osteoblastic type. On follow-up studies, there was a relatively good agreement in the results of bone scintigraphy and radiography. However, there was a good number of cases showing discrepancy between either scintigraphy or radiography and laboratory data. Bone scintigraphy seems to be the most contributory in monitoring bone metastases from prostatic cancer.

Aged↗