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Biomedical subjects

H Tomoike

Publications and source records attributed to H Tomoike.

At least 235 records · Page 13Linked to original sources
PubMed1976

Echocardiographic recognition of the cardiac mural tumor.

An abnormal echocardiographic signal was detected in the myocardium on the echocardiographic examination of the septum and posterior left ventricular wall in a patient found to have lymphosarcoma which was diffusely infiltrated in the myocardium. This echocardiographic abnormality was well correlated with the autopsy findings. Echocardiography appears to be one of useful methods in diagnosing cardiac mural tumor antemortemly.

Autopsy↗
PubMed1975

Rb86 uptake of various organs of the spontaneously hypertensive rats: (a preliminary note).

Twenty spontaneously hypertensive rats (SHR) and 20 control rats were used for measurements of Rb86 uptake of various organs. Hemodynamic measurements and the heart weight to body weight ratio showed a significant and sustained hypertension and increased heart rate in SHR; Ratio of Rb86 uptake in the kidney, brain, liver, adrenal gland, pancreas, and spleen to that in RV was smaller in SHR than that in the control rats. The ratio of Rb86 uptake of inner layer to outer layer of LV, which represents distribution of blood flow to the endocardial layer and epicardial layer, was not different between SHR and the control rats. The fraction of regional flow in the outer and inner cortex, juxtamedulla, and medulla of the kidney was not different between SHR and the control. The present preliminary study may suggest that myocardial blood flow in SHR is greater than that in the control rats. The relationship between cardiac hypertrophy and myocardial flow was discussed.

Adrenal Glands↗
PubMed1975

A study of the effects of propranolol and/or K 1366 on the distribution of Rb86 clearance in the canine heart under selective coronary hypotension.

Effects of beta-blockers o-[2-hydroxy-3-(tert.-butylamino)-propoxy]-benzonitrile (Kö 136 1366) and propranolol, on regional Rb86 clearance in the dog myocardium under selective coronary hypotension were investigated. Selective coronary hypotension of the left circumflex artery below 50 mmHg significantly decreased the Rb86 clearance and its I/O ratio of the involved myocardium. Kö 1366 and propranolol had a general trend to decrease the regional Rb86 clearance in the non-ischaemic region and to increase it in the ischaemic region when compared with that of the control group. Therefore, the gradient of regional Rb86 clearance between the non-ischaemic and ischaemic region may decrease. However, these changes were not statistically significant. Although both Kö 1366 and propranolol groups demonstrated similar haemodynamic changes, a reduction in heart rate was larger with propranolol infusion than with Kö 1366. On the contrary, a decreasing rate in systemic arterial blood pressure was marked with Kö 1366. Epicardial ECG ST elevation was reduced after propranolol infusion, not after saline or KO 1366 infusion.

Animals↗
PubMedDate not supplied

Prolonged repolarization during hypoxemia in epicardial electrogram: difference from ischemia and a competitive action of cyclic AMP.

The effects of regional hypoxemia and ischemia on epicardial electrogram were studied in anesthetized, open-chest dogs. The left circumflex artery (LCx) was cannulated and perfused with either arterial blood or hypoxic solution. A contact electrode for recording monophasic action potential (MAP) was applied to the epicardial site of the LCx area. Epicardial electrograms and MAP in the LCx perfusion territory were recorded 1) just before and at the end of a 2-min coronary occlusion (ischemia) and 2) just before and at the end of a 2-min perfusion of hypoxic solution (hypoxemia). The activation-recovery interval (ARI), defined as an interval from the minimum derivative of the QRS complex to the maximum derivative of the T-wave in the unipolar electrogram, changed linearly with MAP duration during above interventions. The ARI decreased by 29% from 189 +/- 14 to 134 +/- 30 ms during ischemia (p < .001), and it increased by 39% from 183 +/- 11 to 254 +/- 31 ms during hypoxemia (p < .001). Hypoxemia produced a giant negative T-wave whose pattern was not modified by pretreatments with autonomic nerve blockers (propranolol and atropine), a Ca2+ channel blocker (verapamil), an ATP-sensitive K+ channel (KATP blocker (5-hydroxydecanoate or transient outward K+ current (I(to) blocker (4-aminopyridine). Isoproterenol, forskolin or aminophylline inhibited both the appearances of giant negative T and the ARI prolongation. Accordingly, unlike ischemia, hypoxemia prolongs repolarization process and this prolongation is inhibited by the augmentation of intracellular cyclic AMP.

Action Potentials↗
PubMedDate not supplied

Mechanisms of ergonovine-induced hyperconstriction of coronary artery after x-ray irradiation in pigs.

Mechanisms of ergonovine-induced coronary hyperconstriction were examined in vivo and in vitro in miniature pigs. To provoke coronary hyperconstriction, the endothelium of a segment of a major branch of the left coronary artery was denuded in 19 Göttingen miniature pigs (4 to 6 months of age). In Group I (n = 12), the denuded site of the coronary artery was selectively irradiated with 15Gy of x-ray twice, 3 and 4 months after endothelial denudation. The remaining 7 pigs were not irradiated (Group II). The vasoconstrictive effect of intracoronary administration of ergonovine (1 to 1000 microgram) was examined angiographically 3 months (just before irradiation in group I) and 5 months after denudation in the two groups. After the angiographical study, the vessels were isolated and isometric tensions were measured in an organ chamber. In the in vivo studies, ergonovine-induced vasoconstriction at the denuded and x-ray irradiated site in Group I was significantly greater than that at the control site or that at the denuded site in Group II. Pretreatments with serotonin receptor blockers (ketanserin or methysergide) significantly attenuated ergonovine-induced hyperconstriction, while an alpha-adrenergic receptor blocker (prazosin) did not (% inhibition; ketanserin 74 +/- 9%, p < 0.01, methysergide 60 +/- 10%, p < 0.01, prazosin 9 +/- 5%, NS). In the in vitro studies, ergonovine produced significantly greater tension at the denuded and x-ray irradiated site (Group I) than at the control site or at the denuded site (Group II). Ergonovine-induced endothelium-dependent relaxation was impaired at the denuded site in both groups to a similar extent. These results suggest that ergonovine-induced hyperconstriction at the denuded and x-ray irradiated coronary artery resulted mainly from the hyperreactivity of medial smooth muscle mediated by serotonin receptors.

Animals↗
PubMedDate not supplied

Tissue edema and loss of tracer microspheres in infarcted myocardium.

Microsphere loss from the ischemic myocardium was studied in a canine model after 2 and 7 days coronary occlusion. 10 million tracer microspheres (TM) of 7-10 micrograms diameter were injected into the left atrium before and 15 minutes after left anterior descending coronary artery (LAD) occlusion. To determine the tissue water content, dried tissue weight was measured after desiccation. TM content in the nonoccluded left circumflex coronary artery (LCX) area was unchanged before and after coronary occlusion. In the infarcted area, microsphere loss was maximum at the low flow endocardial region averaging 27% and 42% in 2 and 7 days occlusion, respectively. An inverse linear correlation between TM loss and regional blood flow in 2 (r = -0.82, p less than 0.05) and 7 (r = -0.96, p less than 0.01) days coronary occlusion was noted. Water content was increased in the ischemic endocardium by 4.1 and 5.7% in 2 and 7 days occlusion, thus approximately 17% of TM loss was attributed to tissue edema. These results suggest that there is an ischemia-dependent reduction of TM in the ischemic myocardium and that microsphere migration participates in the major part of TM loss. Thus flow measurements by TM may be invalid when this compound is injected during the active phase of microsphere migration or during water content alterations.

Animals↗
PubMedDate not supplied

A newly developed X-ray transparent ameroid constrictor for study on progression of gradual coronary stenosis.

For the experimental studies on chronic coronary stenosis, an ameroid constrictor was modified to facilitate serial cineangiographic evaluation of the degree of arterial narrowing. A radiolucent plastic ring instead of a stainless frame was used to prevent outward swelling of the ameroid material. Coronary cineangiography was performed 10, 20 and 30 days after the implantation of the modified ameroid constrictor on the left circumflex coronary artery (LCX), which could prove the progressive coronary stenosis of 57, 78 and 88% on the respective days. Collateral channels from the anterior descending branch of the left coronary artery to the LCX were demonstrated angiographically in 5 out of the 6 dogs on the 30th day.

Animals↗
PubMedDate not supplied

Linear relationship between perfusion area and infarct size.

The purpose of this study was to develop a technique measuring the perfusion area of the coronary artery preocclusively and to study the relationship between the perfusion area and infarct size. 125I tracer microspheres were selectively injected into the left circumflex coronary artery (LCX) preocclusively, and then the LCX was ligated. 48 hours later the heart was removed, rapidly frozen, and 50-mu transverse sections were obtained from base, middle and apex of the canine left ventricle, and used for autoradiography to measure perfusion area and for tetrazolium staining to measure infarct size. Dogs were divided into 2 groups: group 1 in which the main trunk of the LCX was occluded to produce large infarct (n = 10) and group 2 in which the distal branch of the LCX was occluded to produce small infarct (n = 10). There was a linear correlation between the perfused and infarcted area regardless of a size or location of the perfusion area involved. These results indicate that the extent of infarction is directly proportional to the perfusion area and is not altered by the location in the ventricle.

Animals↗
PubMedDate not supplied

Constriction of the epicardial coronary artery induced by alpha-adrenergic stimulation.

Effects of alpha adrenergic stimulation on diameter change of the epicardial coronary artery were studied in in-situ canine heart. The diameter of the left circumflex coronary artery (LCX) was continuously measured by 10 MHz PZT crystals applied to the external wall of the LCX. Aortic pressure was measured using high fidelity catheter-tip manometer. Enhanced activity of alpha adrenergic receptor by humoral and/or somatic nerve stimulations caused a reduction of the LCX diameter despite of the systemic pressure rise.

Animals↗
PubMedDate not supplied

Vasoconstrictor agents correlatively alter diameter and tension development in isolated pig coronary arteries.

Outer diameter of the isolated pig coronary artery was measured under isotonic conditions using a sonomicrometer, and tension development of a ring preparation was assessed isometrically by a strain gauge transducer. Potassium chloride (KCl), acetylcholine (ACh) and 5-hydroxytryptamine dose-dependently reduced the coronary outer diameter. There was a direct linear relation between the reduction of diameter and tension development by these agents (r = 0.91, n = 15, p less than 0.001). KCl was one of the most potent vasoconstrictors tested and reduced the outer diameter by 35 +/- 1% (n = 15, mean +/- SEM) at 120 mM. ACh produced a transient increase in isometric tension and the reduction of the coronary diameter by ACh was smaller than that seen with KCl, even with a dose which produced the similar peak level of isometric tension by KCl and ACh. It is concluded that changes in the coronary diameter do closely correlate with those in tension development, however, the reduction of coronary diameter after exposure to vasoconstrictive agents is less in phasic than tonic contraction. The latter evidence suggests the importance of both the strength and duration of active vasoconstriction in eliciting coronary spasm.

Acetylcholine↗
PubMedDate not supplied

Prediction of functional recovery in acute myocardial infarction: comparison between sestamibi reverse redistribution and sestamibi/BMIPP mismatch.

BACKGROUND: It has been known that Tc 99m sestamibi/iodine 123 betamethyliodophenylpentadecanoic (123I-BMIPP) (sestamibi/BMIPP) mismatch is an indicator of viable myocardium in acute myocardial infarction (AMI). We have reported that reverse redistribution of sestamibi in AMI indicates the patency of infarct-related artery and a preserved left ventricular function in the chronic stage. In this study we investigated the relationship between reverse redistribution of sestamibi and sestamibi/BMIPP mismatch in patients with AMI. METHODS: Twenty-three patients with AMI who received direct percutaneous transluminal coronary angioplasty underwent both BMIPP and sestamibi SPECT within 2 weeks after onset. Sestamibi images were obtained 1 hour (early) and 3 hours (delayed) after injection of sestamibi. BMIPP imaging was carried out 30 minutes after injection. The left ventricle was divided into 17 segments, and regional myocardial uptakes of the tracers in each segment were scored from 0 (normal) to 3 (no activity). A reverse redistribution pattern was defined as an increase of > or =1 in the regional score at the delayed images. More reduced BMIPP uptake than sestamibi uptake in each segment was determined as sestamibi/BMIPP mismatch. Contrast left ventriculography was performed soon after revascularization and repeated 1 month later. RESULTS: Of 15 patients with sestamibi reverse redistribution, sestamibi/BMIPP mismatch was observed in 14 patients (93%), whereas mismatch was seen in only one of seven patients (14%) without reverse redistribution (p < 0.01). In patients with sestamibi reverse redistribution, regional scores of BMIPP agreed with those of early and delayed images of sestamibi in 51 segments (46%) and in 92 segments (83%), respectively. In the chronic stage, both regional wall motion and left ventricular ejection fraction improved in patients with sestamibi reverse redistribution (wall motion score: 6.7 +/- 2.4 vs 2.7 +/- 2.1, p < 0.01; ejection fraction: 56% +/- 7% vs 64% +/- 8%, p < 0.01), but not in those without reverse redistribution. CONCLUSION: Both reverse redistribution of sestamibi and sestamibi/BMIPP mismatch reflect the recovery of left ventricular function and thus imply myocardial viability in AMI. Because the presence of reverse redistribution of sestamibi agreed with that of sestamibi/BMIPP mismatch, additional BMIPP images can be replaced by the delayed images after a single injection of sestamibi.

Aged↗
PubMedDate not supplied

Haplotype structures of the UGT1A gene complex in a Japanese population.

Genetic polymorphisms of UDP-glucuronosyltransferases (UGTs) are involved in individual and ethnic differences in drug metabolism. To reveal co-occurrence of the UGT1A polymorphisms, we first analyzed haplotype structures of the entire UGT1A gene complex using the polymorphisms from 196 Japanese subjects. Based on strong linkage disequilibrium between UGT1A8 and 1A10, among 1A9, 1A7, and 1A6, and between 1A3 and 1A1, the complex was divided into five blocks, Block 8/10, Block 9/6, Block 4, Block 3/1, and Block C, and the haplotypes for each block were subsequently determined/inferred. Second, using pyrosequencing or direct sequencing, additional 105 subjects were genotyped for 41 functionally tagged polymorphisms. The data from 301 subjects confirmed the robustness of block partitioning, but several linkages among the haplotypes with functional changes were found across the blocks. Thus, important haplotypes and their linkages were identified among the UGT1A gene blocks (and segments), which should be considered in pharmacogenetic studies.

Asian People↗
PubMedDate not supplied

Angiographic evaluation of the coronary vasodilating effect of trapidil in anesthetized closed-chest dogs.

We studied the effect of trapidil on coronary diameters of anesthetized closed-chest dogs using coronary angiography. Trapidil 2 mg/kg i.v. significantly (p less than 0.01) increased the diameter of the proximal (1.96 +/- 0.08 mm), middle (1.29 +/- 0.05 mm), and distal (0.86 +/- 0.03 mm) coronary arteries by 4.2 +/- 1.0, 7.6 +/- 1.2, and 10.8 +/- 2.2%, respectively. Nitroglycerin 20 micrograms/kg i.v. significantly (p less than 0.01) increased the diameter of classes I, II, and III arteries by 4.0 +/- 0.7, 7.7 +/- 1.3, and 7.5 +/- 1.8%, respectively. Ergonovine (0.4 mg i.v.; n = 13) reduced (p less than 0.01) the diameter of all three classes of coronary arteries by 8.2 +/- 1.2, 9.0 +/- 1.0, and 13.3 +/- 1.9%. After pretreatment with ergonovine, trapidil (n = 8) relaxed the coronary arteries from -10.4 +/- 1.7 to -2.4 +/- 1.7% constriction (p less than 0.05). These results indicate that in dogs trapidil dilates coronary arteries in a fashion similar to nitroglycerin and reverses ergonovine-induced coronary vasoconstriction.

Animals↗