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Biomedical subjects

M Ohyanagi

Publications and source records attributed to M Ohyanagi.

68 records · Page 4Linked to original sources
PubMed1985

[Scintigraphic detection of thrombi using indium-111-labeled autologous platelets].

Intracardiac and arterial thrombi were examined by scintigraphy using In-111-oxine labeled autologous platelets. In 22 cases of myocardial infarction including six with ventricular aneurysms, four had positive findings of thrombi on imaging and detected also by echocardiography. All four had ventricular aneurysms. The so-called "moya-moya" echoes (fuzzy echoes) were demonstrated in two of these four cases. We encountered two cases with positive findings on imaging in 13 with mitral valve disease. These two had systemic embolic episodes after scintigraphic examination. "Moya-moya" echoes were detected in the left atrial cavity in four with negative findings on imaging. Positive images were obtained in two of three with acute arterial occlusive disease, and in both cases platelet deposition was observed in the proximal site of obstruction. Though thrombectomy was performed for one of these two cases, no thrombus was detected at the site of platelet deposition. After one month, re-examination revealed only negative findings in all sites in both these patients. In the six cases of aortic aneurysm, three had platelet deposition within their aneurysms, and surgery was performed for these positive cases, but one of them had no thrombus. Positive images were obtained in only one of seven patients with chronic arterial occlusive disease. Coagulation tests and platelet studies were investigated for patients with positive or negative platelet scans. Only the data of the thrombo-test showed a significant difference (97 +/- 9% vs 23 +/- 7%, p less than 0.001). Three cases of positive imaging became negative after anticoagulant therapy. We tried ECT for eight cases 24 hours after injection of In-111-oxine labeled platelets. Three cases showed clear images of thrombi, while the planar images could not detect them at an early stage. Therefore, we propose that ECT can be a useful technique for diagnosing intracardiac thrombi in early stage.

Aged↗
PubMed1984

[Pulsed Doppler echocardiographic evaluation of so-called "moyamoya" echoes in left ventricular aneurysms].

So-called "moyamoya" echoes identified by two-dimensional echocardiography (2 DE) in two cases with ventricular aneurysm were studied by pulsed Doppler echocardiography. The results were as follows: The flow velocity patterns in the left ventricle obtained by pulsed Doppler method were consistent with those observed by the real time 2DE method; the moyamoya echoes moved in a slow, circular fashion, and only a flow with slow velocity toward the transducer was recorded in the posterior area, whereas only a flow with slow velocity away from the transducer was recorded along the interventricular septum during cardiac cycle. The ejection flow velocity at the left ventricular outflow tract was markedly diminished. The flow velocity of the moyamoya echoes was extremely decreased and ranged between 50 and 135 mm/sec. The velocity measurements by M-mode and pulsed Doppler echocardiography gave almost the same values. Thus, the results of the present report suggest that the moyamoya echoes behave like moving blood cells, and that the source of these echoes is the sludging in the stasis of blood.

Aged↗
PubMedDate not supplied

The guanine nucleotide-binding regulatory proteins (G proteins) in myocardium with ischemia.

Guanine nucleotide-binding regulatory proteins (G proteins) play a major role in the regulation of a number of physiological processes, such as stimulation or Inhibition of adenylate cyclase activity or gaiting of ionic channels. Myocardial ischemia could induce the changes in receptor-G protein signal transduction system in the heart. Therefore, this article will focus on the role and alterations of G proteins (especially, Gs and Gi) in myocardial ischemia. The Gi protein rapidly loses functional activity during very early myocardial ischemia. In contrast to Gi protein, the function of Gs protein during this phase has not been evaluated. Moreover, the changes in Gs protein after 30 min of ischemia are contradictory. However, the sensitization of the adenylate cyclase activity in the very early phase of acute ischemia is gradually replaced by a decrease in adenylate cyclase activity with prolonged ischemia. The decrease in the function and amount of Gs protein may be one of the factors that induce these changes. The function of Gs protein was also decreased in the canine hearts with ischemia and reperfusion. In contrast to ischemia and reperfusion, there are no significant alterations in G proteins and modulation of adenylate cyclase in the stunned myocardium. It has become increasingly evident that Gi protein may play an important role in the cardioprotective effects of preconditioning. When beta-adrenoreceptor densities are reduced in chronic myocardial ischemia, decreased in the amount and function of Gi protein and increased amount of Gs protein may play the role in preservation of the adenylate cyclase activity. These alterations in G proteins may play the important role in the myocardial function during myocardial ischemia.

Animals↗
PubMedDate not supplied

Clinical usefulness of iodine 123-labeled fatty acid imaging in patients with acute myocardial infarction.

BACKGROUND: Iodine 123-labeled 15-(p-iodophenyl)-3R,S-methylpentadecanoic acid (BMIPP) has recently been developed, since normal myocardium metabolizes free fatty acids. This study investigated the clinical usefulness of BMIPP imaging in patients with acute myocardial infarction (MI), particularly in the detection of stunned myocardium in patients who underwent acute coronary revascularization. METHODS: The subjects were 41 patients with acute MI who had undergone emergency coronary revascularization. Both BMIPP and thallium-201 images at rest were obtained during the subacute phase. The myocardial distribution of radiotracers was quantified by generating circumferential count-distribution profile analysis. Initial 201Tl imaging, delayed 201Tl imaging, and BMIPP imaging were performed, and the mean count densities in the infarct region (initial 201Tl images [TL1], delayed 201Tl images [TL2], and BMIPP images in the infarct region [BM], respectively) were obtained. The differences between mean count densities (TL1-BM: BM subtracted from TL1; TL2-BM: BM subtracted from TL2) were also calculated. RESULTS: BM showed a higher correlation with wall motion data by echocardiography (WM) in the acute phase than other nuclear imaging tests, whereas TL2 showed the highest correlation with WM in the chronic phase. Acute to chronic WM improvement showed a good correlation with TL2-BM. CONCLUSION: Single photon emission computed tomography imaging with BMIPP is a candidate for providing the "memory image" of ischemic damage, whereas TL2 reflects all viable tissue. The mismatch between the tracers can serve as an indicator of myocardial stunning.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

Detection of inflammation in aortic aneurysms with indium 111-oxine--labeled leukocyte imaging.

BACKGROUND: The exact cause of aortic aneurysms is not completely understood. Histologically, the atherosclerotic lesions present in an aneurysm contain numerous inflammatory cells. This finding represents active atherosclerosis, which can cause lesion expansion. In this study we investigated the role of scintigraphy in the evaluation of inflammation in aortic aneurysms. METHODS AND RESULTS: We performed imaging using indium 111-oxine--labeled leukocytes in 14 patients with aortic aneurysms (10 thoracic and 4 abdominal) diagnosed by computed tomography. Peripheral blood evidence of inflammation was assessed on the same day. In 8 patients who subsequently underwent graft replacement of the aneurysm, the excised specimen was examined for evidence of inflammatory infiltration and correlated with the scintigraphic findings. Scintigraphic accumulation of labeled leukocytes was present in 10 of the 14 patients. Although all patients had a small increase in the erythrocyte sedimentation rate, there was no significant difference in the erythrocyte sedimentation rate between patients with positive and negative scintigram results. In 5 of the 8 surgical patients with positive scintigram results, the resected specimens demonstrated numerous inflammatory cells in the adventitia of the aortic wall and atherosclerotic changes in the media. There was no correlation between the presence of periaortic inflammatory adhesions at the time of surgery and the scintigraphic results. CONCLUSIONS: The accumulation of In-111-oxine--labeled leukocytes is a potentially useful scintigraphic marker of inflammatory infiltration in aortic aneurysms.

Aged↗
PubMedDate not supplied

Simple methods of assessing physical activity in patients with chronic heart failure.

This article reviews simple, noninvasive ways to assess physical activity in patients with chronic heart failure. Six- or 9-minute walk tests appear to be useful not only for selecting patients with relatively advanced heart failure but also as prognostic screening tests. The Master-Borg test (Master's two-step testing and 10-point Borg scale) is useful for assessing symptoms during exercise. Weekly pedometer counts show that the level of activity in patients with heart failure is dramatically less than in healthy controls. Physical activity can be determined directly by an ambulatory calorie counter that measures step scores and energy expenditure using specific accelerometers. Careful clinical interviewing regarding symptoms, together with submaximal exercise testing and use of motion sensors, are recommended as useful, simple, noninvasive alternatives for assessing physical activity in this patient population. (c)2000 by CHF, Inc.

Journal Article↗
PubMedDate not supplied

In vitro analysis of alpha-adrenoceptor interactions with the myogenic response in resistance vessels.

The interaction of alpha 1- and alpha 2-adrenoceptor constriction of isolated rat cremaster small arteries (mean diameter +/- SEM, 114 +/- 5 microns) with the myogenic mechanism was examined with in vitro videomicroscopy. Microdissected vessels were double-cannulated with glass micropipets in a tissue bath, and intraluminal pressure was set at 65 mm Hg baseline pressure. Norepinephrine (NE) concentration-response curves were obtained alone and in the presence of prazosin or rauwolscine to establish the concentration of NE required to selectively stimulate alpha 1- or alpha 2-adrenoceptors. A bimodal response was produced by NE alone, indicating interaction with more than one receptor population. Rauwolscine and prazosin each produced dextral displacement at low (< 0.1 microM) NE concentrations. However, while prazosin exhibited competitive antagonism, rauwolscine did not antagonize NE at concentrations > or = EC50 value. Thus, both alpha 1- and alpha 2-adrenoceptors mediate constriction at low NE concentrations, but only alpha 1-receptors contributed to constriction at intermediate and high concentrations. These data are in contrast to previous findings for the same vessels studied in vivo. Diameter responses to increases and decreases in transmural pressure from baseline were examined in the relaxed (passive) state with nitroprusside present, during spontaneous intrinsic tone, and during induced alpha 1- or alpha 2-tone (EC20 concentration of NE plus rauwolscine or prazosin). Myogenic constriction during increases in lumen pressure and myogenic inhibition of tone during decreases in pressure were greatest during alpha 2-tone, less during intrinsic tone and least during alpha 1-tone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

The role of guanine nucleotide binding proteins in hamsters with myocardial hypertrophy.

To clarify the role of the guanine nucleotide binding proteins (G-proteins) in the pathogenesis of myocardial hypertrophy, we investigated the alterations in myocardial G proteins in 20-week-old F1b hamsters with pressure overload induced for 3 days (3-day AS), 7 days (7-day AS) and 14 days (14-day AS) by the stenosis of the abdominal aorta, and in 4- and 20 week-old BIO 14.6 Syrian hamsters (4-wk and 20-wk BIO) with genetic myocardial hypertrophy. The hearts of 7-day AS, 14-day AS and 20-wk BIO with left ventricular hypertrophy exhibited a decrease in the mRNA levels detected by Northern blot analysis and protein levels of G protein detected by Western blot analysis as compared with sham-operated and age-matched F1b hearts. The function of Gs or Gi showed a concomitant reduction in both models of myocardial hypertrophy. The hearts of 3-day AS and 4-wk BIO without myocardial hypertrophy showed no changes in G proteins as compared with sham-operated and age-matched F1b hearts. These results suggest that a decrease in G proteins is not involved in the pathogenesis of myocardial hypertrophy, but that myocardial hypertrophy reduced the G proteins.

Adenylyl Cyclases↗
PubMedDate not supplied

[Comparison of initial and delayed myocardial imaging with beta-methyl-p-[123I]-iodophenylpentadecanoic acid in acute myocardial infarction].

Myocardial imaging using beta-methyl-p-[123I]-iodophenylpentadecanoic acid (BMIPP) of 15 patients with acute myocardial infarction was performed to assess "fill-in" and "washout" defects in the delayed myocardial image. The initial and delayed images were evaluated by a visual and quantitative washout rate method. Visual judgement found 8/180 (4%) segments showed "fill-in" defects, and 24/180 segments (13%) showed "washout" defects. There was no relationship between days from onset to the study and the frequency of fill-in and washout defects. The mean washout rate in the segments with "fill-in" defects was 9.0 +/- 16.6%, and that of "washout" defects was 24.9 +/- 18.1% which was significantly higher than in controls (8.7 +/- 15.4%, p < 0.05). There was no correlation between mean washout rate and total blood lipids, total cholesterol, triglyceride and HDL-cholesterol. Therefore, neither time from onset nor blood lipids level was related to changes from the initial image to the delayed image. These changes may be due to relative (false) findings due to changes in circumference, and may be based on myocardial characteristics after myocardial infarction and/or reperfusion.

Adult↗