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Biomedical subjects

M Okada

Publications and source records attributed to M Okada.

At least 1,369 records · Page 76Linked to original sources
PubMed1987

Directly-acting mutagens formed from N-nitroso-N-(formylmethyl)alkylamines.

Directly-acting mutagens formed from N-nitroso-N-(formylmethyl)alkylamines (I) were isolated and identified as N-nitroso-N-alkyl-1-hydroxyimino-2-oxoethylamines (II). Their structures were elucidated on the basis of nuclear magnetic resonance spectra and confirmed by leading to their crystalline 2,4-dinitrophenylhydrazone. II (alkyl = ethyl and n-butyl) were strongly mutagenic to Salmonella typhimurium TA1535 and Escherichia coli WP2 hcr- without metabolic activation, while II with a tert-butyl group was not mutagenic. The formation of II from I is considered to proceed by the nitrosation of I, indicating a possible involvement of a formylmethyl metabolite in the carcinogenesis of nitrosamines with a 2-hydroxyethyl group.

Animals↗
PubMed1987

[V1P-terminal force evaluated by left ventricular inflow velocity patterns in pulsed Doppler echocardiography].

The relationship between V1P-terminal force (V1-PT) and the characteristics of left ventricular (LV) diastolic filling and atrial contraction were evaluated using LV inflow velocity patterns obtained by pulsed Doppler echocardiography. Subjects consisted of 54 patients with old myocardial infarction, 56 with essential hypertension, 48 with angina pectoris, 19 with dilated cardiomyopathy, and 16 with miscellaneous disease other than of mitral valve lesions. The patients were classified as the positive group: V1-PT less than or equal to -0.04 mmsec, intermediate group: 0 greater than V1-PT greater than -0.04 mmsec, and negative group: V1-PT greater than or equal to 0 mmsec. The following were the results obtained: 1. In the positive group, the rapid filling wave (R) had reduced velocity, the prolonged deceleration time and the decreased acceleration and deceleration ratios. 2. In the positive group, velocity of the atrial contraction wave (A) was increased and the atrial contraction time was prolonged compared to the other groups. 3. In the positive group, the A/R was greater than in the other groups. 4. In the positive and intermediate groups, V1-PT correlated significantly with the A/R (r = 0.83, p less than 0.01), R (r = -0.58, p less than 0.01) and A (r = 0.48, p less than 0.01). In the positive group, LV inflow volume was decreased in the rapid filling phase. In the atrial contraction phase, the inflow volume was increased to compensate for loss of inflow volume in the rapid filling phase. These findings suggested that LV diastolic filling was disturbed in the positive group. In conclusion, the value of V1-PT is influenced by any disturbance of LV diastolic filling.

Adult↗
PubMed1987

[Effect of valve replacement on left ventricular function in chronic aortic regurgitation].

To ascertain the optimal time for surgery in chronic aortic regurgitation (AR), 66 patients with and without surgical correction were reviewed from the standpoint of left ventricular (LV) function based on their serial echocardiographic studies. Aggravation of the clinical status was usually associated with enlarged LV dimension, decreased %fractional shortening (%FS), and increased LV end-systolic meridional stress (sigma m). Fourteen patients developed congestive heart failure during follow-up periods of up to five years, and most of their echocardiographic findings showed %FS less than 27%, and LV end-systolic dimension (LVD) greater than 50 mm. Thirty-two patients underwent surgery. Preoperatively, sigma m and %FS were closely correlated, including cases whose %FS was decreased. This linear regression equation became steeper with dobutamine administration; however, in patients, whose mean preoperative LVD value exceeded 50 mm, the %FS remained depressed (delta FS less than 6%) and sigma m did not significantly decrease during dobutamine administration. Marked or moderate resolution of LV dilatation and hypertrophy was observed in all patients postoperatively. Compared to patients with preoperative %FS greater than or equal to 27%, much more time was required for recovery of patients with %FS less than 27%, though their %FS and their exercise capacity improved within two years of surgery. Immediate postoperative recovery was observed in cases with excellent preoperative response to dobutamine (delta FS greater than or equal to 6%). However, in patients with severely depressed preoperative %FS less than 20%, postoperative improvement was not so marked and the surgical results were unsatisfactory. From these results, we concluded that the optimal time for surgery for AR is when %FS = 27% and LVDs = 50 mm.

Adult↗
PubMed1987

Aging and urinary bladder carcinogenesis induced in rats by N-butyl-N-(4-hydroxybutyl)nitrosamine.

The effect of age on induction of carcinogenesis by N-butyl-N-(4-hydroxybutyl)nitrosamine [(BBN) CAS: 3817-11-6] in the urinary bladder epithelium was examined in 130 male and 130 female F344 rats. Rats of both sexes 6, 52, and 98 weeks old were given 0.025% BBN in their drinking water for 20 weeks. Then approximately half the rats were sacrificed, while the rest were maintained without further treatment for 10 weeks. Examination of the rats revealed an age-related increase in the induction of urinary bladder carcinoma, although the total intakes of BBN and urinary excretions of its proximate carcinogen were not age related. Rats treated with BBN at 98 weeks of age developed more squamous cell carcinomas and invasive carcinomas than the 2 younger groups. This study demonstrated an increased risk of urinary bladder carcinogenesis with age in animals.

Aging↗
PubMed1987

[A new method of vascular anastomosis by CO2 laser: experimental and clinical study].

It is difficult to maintain the long-term patency after conventional anastomosis especially for the small caliber vessels. Since 15 years we have performed aortocoronary bypass with suture materials for the patients with ischemic heart disease. There are some problems in maintaining the long-term patency of the bypass grafts. Low energy CO2 laser was utilized to make vascular anastomosis with a few stay sutures. Vascular anastomoses (side-to-side, end-to-end, end-to-side) were carefully made by CO2 laser in the regions of the femoral arteries and veins, the carotid arteries and jugular veins in dog. A-C bypass was also successfully carried out between the internal mammary artery and the left anterior descending artery under the beating heart in experiment. Outputs of 20-40 mW and irradiation times of 6-12 sec/mm were optimal conditions for anastomosis of the small caliber vessels. There were no problems in the intensity and the healing of the anastomotic sites in comparison with the conventional suture method. On the basis of these excellent experimental results a low energy CO2 laser was employed clinically for vascular anastomosis of the peripheral vessels in 28 patients with angina pectoris or chronic renal failure and cardiac failure. There were no complications such as bleeding and suture line aneurysm after surgery. In conclusion, vascular anastomosis by laser might be recommended in performing with safety and rapidity for small caliber vessels.

Adult↗
PubMed1987

Ricinus communis agglutinin I blocks the binding of human anti-renal basement membrane antibodies to the kidney.

Whether or not glycosyl moieties of glycoproteins present in human renal basement membranes are related to the sites where anti-basement membrane antibodies bind was examined by blocking experiments using several kinds of lectin. Ricinus communis agglutinin I (RCA I), specific for galactose, blocked the binding of human anti-glomerular basement membrane (GBM) and anti-tubular basement membrane (TBM) antibodies to renal basement membranes. This lectin also diminished the binding of rabbit anti-laminin antibody, but did not inhibit the binding of mouse anti-fibronectin or rabbit anti-human TBM antibodies. These findings suggest that the binding sites of human anti-GBM and anti-TBM antibodies and heteroantibodies to laminin are closely related to the galactose moieties in glycoproteins of human renal basement membranes. Whether the galactose-containing branches are associated with the nephritogenicity of human anti-GBM and anti-TBM antibodies or simply exist adjacently to the antibody binding sites remains to be discerned.

Antibodies↗