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Biomedical subjects

I Yamaguchi

Publications and source records attributed to I Yamaguchi.

At least 271 records · Page 15Linked to original sources

Identification of Ten Gibberellins from Sporophytes of the Tree fern, Cyathea australis.

Ten gibberellins (GAs) have been identified by Kovats retention indices and full mass spectra from GC-MS analysis of purified extracts of sporophytes of the tree-fern, Cyathea australis. These include the known GA(1), GA(4), GA(9), GA(15), GA(24), GA(35), and GA(58) and three new GAs, 12beta-hydroxyGA(9) (GA(69)), 12alpha-hydroxyGA(9) (GA(70)) and 12beta-hydroxyGA(4) (GA(71)). The structure of GA(71) was established by the preparation and characterization of its methyl ester (as a metabolite of GA(4) methyl ester in a culture of prothallia of Lygodium japonicum).

Journal Article↗

Serial determinations of serum enzymes following aorta-coronary bypass surgery and acute myocardial infarction.

Serial determinations of serum creatine kinase (CK), cardio-specific isoenzyme of CK (CK-MB), glutamic oxaloacetic transaminase (GOT) and alpha-hydroxybutylate dehydrogenase (HBD) were made in 29 consecutive patients undergoing aorta-coronary (AC) bypass grafting, and the results were compared with those in 31 patients with acute myocardial infarction (AMI). Postoperatively, all patients had an uneventful postoperative course and there was no evidence of AMI. The time course of enzyme activity following surgery was characterized by 1) shortening of peak activity time of all enzymes except CK, 2) rapid disappearance of CK-MB, 3) prolonged normalization of GOT and HBD. Peak activities of CK, CK-MB, GOT and HBD in AC bypass patients were 801 +/- 77, 46 +/- 6, 100 +/- 9 and 718 +/- 32 IU (mean +/- SEM), respectively, which were equivalent to 46%, 12%, 22% and 47% of those in AMI. The degree of postoperative CK-MB elevation was influenced by the duration of the operation and the extracorporeal circulation, and the number of grafts bypassed. The peak CK-MB activity did not correlate with the CK peak. The ratio of CK-MB to CK was much smaller in AC bypass than in AMI (6.5 +/- 1.8 vs. 20.1 +/- 1.4%). It was concluded that serum enzyme elevations after AC bypass surgery largely reflected enzyme release from the skeletal muscle rather than the myocardium.

Adult↗

Cardiovascular response to exercise in the healthy male septuagenarians: with reference to plasma norepinephrine.

Hemodynamics during supine graded exercise were measured in 7 healthy aged and 20 young. The maximal work load in the aged was about one half of that in the young. Cardiac output (CO) increased linearly with increasing work load, but its maximal value was markedly lower in the aged than in the young (11.2 +/- 1.1 vs. 19.7 +/- 1.0 liter)min; M +/- S.E.) Although CO at each level of submaximal exercise was essentially the same in both groups, the aged had smaller increases in stroke volume (SV) and systemic vascular conductance (SC), corresponding to larger increases in heart rate and mean blood pressure. An increase in SV during exercise was achieved from a greater systolic emptying force rather than Frank-Starling effect. A small increase in SC suggested the decreased arteriolar vasodilation in the working muscles. Thus, in the aged, both the reduced myocardial contraction reserve and increased afterload contributed to a small increase in SV during exercise. Plasma norepinephrine concentration in the aged was higher than in the young at rest (240 +/- 37 vs. 159 +/- 30 pg/ml), and both groups showed similar high levels at exhaustion (715 +/- 121 vs. 702 +/- 99 pg/ml). These demonstrated that the sympathetic activity during exercise remained unchanged and the cardiac response to sympathetic stimulation declined with age.

Adult↗

Dissociation between regional myocardial dysfunction and ECG changes during myocardial ischemia induced by exercise in patients with angina pectoris.

In order to investigate the relation between regional myocardial function and electrical changes during myocardial ischemia in humans, left ventricular echocardiogram and ECG were recorded during supine ergometer exercise in 16 patients with coronary artery disease until angina or ischemic ECG appeared. During exercise in 13 patients a decrease of left ventricular posterior wall excursion or of interventricular septum excursion occurred earlier than the appearance of ST-T change on ECG. In two patients the excursion decreased at the same time as the ST-T change. Significant regional myocardial dysfunction occurred at 30 +/- 15 seconds and ECG changes occurred at 90 +/- 60 seconds (p less than 0.001). Percent systolic wall thickening occurred in similar fashion. Results support the hypothesis that regional contractile abnormalities may provide a more sensitive indicator of myocardial ischemia than ST-T changes in humans.

Aged↗