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Biomedical subjects

H Sakuma

Publications and source records attributed to H Sakuma.

At least 91 records · Page 5Linked to original sources
PubMed1996

Magnetic resonance imaging in ischemic heart disease.

The clinical use of MR imaging in ischemic heart disease is still limited, although this is the major cardiac disease afflicting populations of many countries. However, with the recent development of faster MR techniques, MR imaging provides multiple capabilities for the evaluation of most aspects of ischemic heart disease. We described the potential application of MR imaging for identifying and quantifying morphologic and functional alterations caused by myocardial infarction and ischemia; the contribution of MR contrast media to improve tissue characterization and to identify ischemic myocardium; and the application of fast MR imaging techniques for assessing anatomy and blood flow in the native coronary arteries and bypass conduits. With continued development of these capabilities, MR imaging has the potential to be a comprehensive noninvasive imaging modality in ischemic heart disease.

Contrast Media↗
PubMed1996

Coronary flow reserve: noninvasive measurement in humans with breath-hold velocity-encoded cine MR imaging.

PURPOSE: To measure coronary vasodilator reserve with breath-hold velocity-encoded cine magnetic resonance (MR) imaging. MATERIALS AND METHODS: Eight healthy adult volunteers underwent 1.5-T MR imaging. Velocity-encoded cine images were acquired at seven to 13 temporal phases in 25 seconds, with k-space segmentation and view-sharing reconstruction (+/- 1 m/sec velocity-encoding value) (repetition time msec/echo time msec = 16/9). Flow velocity in the left anterior descending (LAD) artery was measured twice before and twice after administration of dipyridamole (0.56 mg per kilogram of body weight). RESULTS: Peak diastolic coronary flow velocity in the LAD artery was 14.8 cm/sec +/- 1.9 (mean +/- standard deviation) in the baseline state. It increased significantly (P< .01) to 46.3 cm/sec +/- 10.2 after dipyridamole administration, with an average coronary reserve of 3.14 +/- 0.59. Interstudy and interobserver reproducibilities for measurement of peak diastolic velocity were, respectively, 9.5% +/- 1.6 and 7.0% +/- .2.5 in the baseline state and 6.8% +/- 2.2 and 3.4% +/- 1.5 after dipyridamole administration. CONCLUSION: Breath-hold velocity-encoded cine MR imaging provided reproducible assessment of coronary flow reserve in humans.

Adult↗
PubMed1996

Heart disease: functional evaluation with MR imaging.

Diagnosis of cardiovascular disease requires precise assessment of both morphology and function. Nearly all aspects of cardiovascular function can be quantified with fast magnetic resonance (MR) imaging techniques. Conventional and breath-hold cine MR imaging can provide precise and highly reproducible measurements of global and regional function of the left and right ventricles. Velocity-encoded cine (VEC) MR imaging provides measurements of blood flow in the heart and great vessels. Contrast-prepared fast gradient-echo sequences can be used to monitor the first-pass dynamics of contrast media, thus defining selective regional myocardial perfusion. Recently, the feasibility of using breath-hold VEC MR imaging to measure flow velocity in native coronary arteries and coronary revascularization conduits has been shown. This will most likely provide a noninvasive method for testing coronary vasodilator reserve and may emerge as a new method for detecting asymptomatic coronary artery disease.

Coronary Circulation↗
PubMed1996

Nocturnal blood pressure and silent cerebrovascular lesions in elderly Japanese.

BACKGROUND AND PURPOSE: We conducted a cross-sectional epidemiological survey using ambulatory blood pressure monitoring and brain MRI in a cohort from northern Japan to determine whether an inappropriately low nocturnal blood pressure, or an excess fall in nocturnal blood pressure, might be responsible for silent cerebrovascular lesions in the elderly. METHODS: Untreated subjects over 55 years and under 64 years of age (late middle age; 24 men and 46 women, 60% of eligible people) and over 65 years and under 75 years of age (elderly; 29 men and 52 women, 91% of eligible people) participated in the study. We evaluated the relationship between the amplitude (Daytime Average-Nighttime Average) or the rate ([Daytime Average-Nighttime Average]/Daytime Average) of the fall in nocturnal blood pressure and the incidence of silent cerebrovascular lesions on MRI (number of lacunar infarctions or extent of periventricular hyperintensity). RESULTS: The amplitude or the rate of the fall in nocturnal blood pressure in elderly women with one or two lacunar infarctions was significantly higher than that in those without such infarctions. There was a significant positive correlation between the amplitude or the rate of the fall in nocturnal blood pressure and the extent of periventricular hyperintensity in the elderly women. This relationship was observed in women, but not in men, of late middle age; this was not seen in elderly men. CONCLUSIONS: Results indicate that an inappropriately low nocturnal blood pressure, or an excessive fall in nocturnal blood pressure, is associated with ischemic silent cerebrovascular lesions, at least in elderly women. Treatment of hypertension in such women should be administered with care and with regard to nocturnal blood pressure.

Age Distribution↗
PubMed1996

Peripheral neuroepithelioma (peripheral primitive neuroectodermal tumor) of the uterine cervix.

We report here a case of peripheral neuroepithelioma arising in the uterine cervix. A 44-year-old female had complained of irregular genital bleeding for several months and was diagnosed as extraosseous Ewing's sarcoma (EOE) from biopsy specimens initially. The tumor cells, which were intensely stained by periodic acid-Schiff (PAS) and digested with diastase, were uniformly small and round, had hyperchromatic nuclei and scant, indistinct cytoplasm. The surgically-removed tumor cells were immunohistochemically stained with antisera against neuro-specific enolase (NSE), tyrosine hydroxylase. In ultrastructural study, neurosecretory granules were observed. Finally we diagnosed this case as peripheral neuroepithelioma (peripheral primitive neuroectodermal tumor, PNET).

Adult↗
PubMed1996

The psychological factors of a premature response based on contingent negative variation.

The psychological factors of a premature response on simple reaction-time tasks were examined by comparing the difference between control responses (33 samples) and premature responses (33 samples) using the index of Contingent Negative Variation (CNV). The first (warning) stimulus was a click, the second (imperative) stimulus was a colored circular figure presented on a CRT, and the interstimulus interval was set at 3 sec. 72 trials were administered to the 24 subjects, then 33 artifact-free CNV data in a premature response were shown. Analyses indicated that CNV amplitudes in the premature response were lower than those in the control response at frontal position. Especially in the premature response, CNV waveforms stayed around baseline toward S2 at F3 and F4. In the analyses of variance, every CNV component (early, late, and whole components) at F4 or FZ was significantly lower for the premature response. These results suggested that the optimal prediction, arousal, and attention do not seem to be maintained in a premature response.

Acoustic Stimulation↗
PubMed1996

Effects on contingent negative variation of set created by anticipating variable foreperiods.

The influence of set on a simple reaction time task was examined by comparing the differences of psychological factors between a group of subjects who expected and experienced a fixed foreperiod Control condition: 12 subjects) and another group of subjects who were instructed to expect variable foreperiods but experienced the same fixed foreperiod (Instruction condition: 11 subjects), using the index of contingent negative variation (CNV). The foreperiod of simple reaction time task in each condition was fixed at 3 sec. Subjects were required to respond to 2 blocks of 24 trials, and each instruction was presented between blocks. On the second block CNV amplitudes were higher in the instruction condition as was every CNV component (early late, and whole component). The set created by anticipating variable foreperiods seems to increase cerebral activity, arousal, and attention during simple reaction time tasks.

Adolescent↗
PubMed1996

Very fast cardiac imaging.

With very fast MR imaging techniques, myocardial perfusion can be assessed by monitoring the changes of myocardial signal intensity over time following bolus injection of a contrast medium. Very fast MR imaging techniques also allow for freezing of cardiac motion that is important for coronary MR angiography and their high temporal resolution allow for coronary flow reserve measurements. In the current overview, basic principles and strategies of very fast cardiac MR imaging are presented. In the second part, applications of these fast sequences in the fields of myocardial perfusion, coronary MR angiography, and low measurements are presented.

Animals↗
PubMed1995

Muscle cramps and elevated serum creatine phosphokinase levels induced by beta-adrenoceptor blockers.

We have assessed the propensity of beta-adrenoceptor blockers to cause muscle cramps and to raise the serum creatine phosphokinase (CPK) level in 78 patients with essential hypertension. After a control period, a beta-adrenoceptor blocker without intrinsic sympathomimetic activity (ISA; propranolol, metoprolol or arotinolol) was administered for three months. Thereafter, the patients were randomised to receive a beta-adrenoceptor blocker with ISA (pindolol or carteolol) for three months or a beta-adrenoceptor blocker without ISA for a further three months. This pattern was continued until all beta-adrenoceptor blockers had been given. At the end of each period, CPK and CPK-MB levels were measured. Of the 78 subjects, muscle cramps occurred in 27 during treatment with pindolol and 32 during treatment with carteolol. No complaints were made by subjects treated with propranolol and arotinolol, but muscle cramps were reported in 2 treated with metoprolol. While muscle cramps were caused both by pindolol and carteolol in 16 subjects, they were caused by either of these drugs in the remainder of the subjects. Muscle cramp occurred mainly in the calves when the patients were in bed at night. Serum CPK and CPK-MB levels increased significantly during treatment with pindolol (control period vs pindolol, CPK = 96 vs 133 IU.ml-1, CPK-MB = 14 vs 18 IU.ml-1) or carteolol (CPK = 117 IU.ml-1, CPK-MB = 18 IU.ml-1) while the levels during treatment with propranolol, arotinolol and metoprolol did not change from those in the control period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1995

Familial nesidioblastosis in two sisters.

We herein present two female siblings with persistent hyperinsulinemic hypoglycemia in the neonatal period who were diagnosed as having familial nesidioblastosis. Despite both the administration of diazoxide and the intravenous infusion of glucose, one of the affected infants died of severe metabolic acidosis at about 1 month of age, before pancreatectomy could be performed. The other, in whom the disorder was diagnosed early, also failed to respond to conservative medical treatment and ultimately required a 99% pancreatectomy for control of hypoglycemia. A third female sibling was normal. The possibility of familial nesidioblastosis should thus be considered in the case of neonatal intractable hypoglycemia to ensure a prompt diagnosis and allow for early surgical intervention when indicated. The relevant literature on this life-threatening disorder is also reviewed.

Adenoma, Islet Cell↗
PubMed1995

Multislice measurement of first-pass transit of gadobenate dimeglumine in normal and ischemic myocardium in dogs.

RATIONALE AND OBJECTIVES: We monitored the differences in the first passage of gadobenate dimeglumine through normal and ischemic myocardium with left anterior descending (LAD) coronary artery occlusion in dogs. METHODS: Dynamic multislice images of the heart were taken on a 1.5-T magnetic resonance (MR) imager. In six normal dogs, inversion recovery (IR)-prepared fast gradient-recalled echo (GRE) images were acquired at five doses of gadobenate dimeglumine (0.005-0.1 mmol/kg). First passage of the contrast medium through normal and acutely ischemic myocardium were monitored in seven dogs subjected to LAD coronary artery occlusion. RESULTS: IR-prepared GRE images showed a dose-dependent increase in the signal intensity (SI) of the myocardium. In dogs with LAD coronary artery occlusion, there was a significant increase in the SI of normal myocardium (p < .01) than in ischemic myocardium after injection of 0.025 mmol/kg gadobenate dimeglumine. CONCLUSION: The first-pass dynamics of gadobenate dimeglumine through normal and ischemic myocardium can be monitored with a multislice acquisition using a clinical MR imager and differentiated between normal and ischemic myocardium in dogs.

Animals↗
PubMed1995

Coronary artery stenosis: detection with contrast-enhanced MR imaging in dogs.

PURPOSE: To monitor with fast gradient-echo magnetic resonance (MR) imaging the dynamics of gadolinium benzyloxypropionictetraacetate (gadobenate) dimeglumine on myocardial signal intensity in dogs with critical left circumflex coronary artery stenosis. MATERIALS AND METHODS: Fast gradient-echo MR images were acquired in a short axis of the left ventricle. Two bolus injections of 0.05 mmol/kg gadobenate dimeglumine were administered in the basal state after stenosis and after infusion of 0.5 mg/kg dipyridamole. RESULTS: In the basal state, there was an equivalent increase in signal intensity of normal and hypoperfused myocardium during the first pass. Dipyridamole increased left anterior descending flow (287% +/- 36; P < .05) and decreased left circumflex flow (65% +/- 14; P < .05). The magnitude of signal intensity increase during the second bolus in the hypoperfused region was less than that of normal myocardium (P < .05). Contrast-enhanced images showed the hypoperfused region as smaller than the postmortem measurement (43.8% +/- 3.3; P < .05). CONCLUSION: Contrast-enhanced fast MR imaging in the vasodilated state allows detection of hypoperfused myocardium in the presence of critical coronary stenosis.

Animals↗
PubMed1995

Pressor effect of recombinant human erythropoietin: results of ambulatory blood pressure monitoring and home blood pressure measurements.

We investigated whether treatment of anemic hemodialysis patients with a low dose of recombinant human erythropoietin (erythropoietin) for a short period would increase their blood pressure. Ambulatory blood pressure monitoring and home blood pressure measurements were used to detect minute increase in blood pressure. Thirty-two patients with a hematocrit of 25% or less received erythropoietin at the dose of 4500 IU/week, by the intravenous route for 8 weeks. Erythropoietin increased the hematocrit from 20.9 +/- 2.1 to 26.2 +/- 2.1%. Erythropoietin elevated mean ambulatory blood pressure by 5 mmHg or more in two-thirds of patients (n = 20; pressor group), while it elevated home mean blood pressure by 5 mmHg or more in one-third of patients (n = 11). An increase in clinic mean blood pressure by more than 5 mmHg was observed only in one-fourth of patients (n = 7). Circadian variation of blood pressure (nocturnal fall and diurnal rise) had been attenuated in the patients of the pressor group before erythropoietin treatment and erythropoietin decreased the nocturnal fall of blood pressure further more. Erythropoietin elevated nocturnal blood pressure more than diurnal blood pressure. Therefore, the increase in blood pressure induced by erythropoietin was detected more reliably by ambulatory blood pressure monitoring. There was no relation between the change in hemoglobin concentration and the increase in ambulatory blood pressure induced by erythropoietin. Erythropoietin tended to decrease cardiac output and plasma volume while it increased total peripheral resistance. It also decreased plasma norepinephrine and vasopressin levels but did not affect other humoral factors. Although the pressor effect of erythropoietin treatment for 8 weeks at the dose of 4500 IU/week was not evident on clinic blood pressure measurements, any increase in blood pressure determined by ambulatory blood pressure should be treated carefully to reduce the risk of a cardiovascular complication in patients receiving hemodialysis.

Aldosterone↗
PubMed1995

Concurrent use of granulocyte colony-stimulating factor with low-dose cytosine arabinoside and aclarubicin for previously treated acute myelogenous leukemia: a pilot study.

We used a new chemotherapy regimen for the treatment of 18 consecutive patients with relapsed AML (median age 44 years, range 18-74). The regimen consisted of low-dose cytosine arabinoside (10 mg/m2/12 h, usually day 1 to 14), low-dose aclarubicin (10-14 mg/m2/day, day 1 to 4), and concurrent use of G-CSF (200 micrograms/m2/day) (CAG regimen). Overall, 15/18 patients (83%) achieved complete remission (CR) after one or two courses, including eight out of ten refractory patients with early relapse, second or subsequent relapses, and/or resistant relapse. Two of three patients who relapsed, achieved CR again after reinduction with a modified CAG regimen. Fourteen of the 15 complete remitters received consolidation therapy with the CAG regimen modified, followed by oral busulfan in eight cases, and by allogeneic bone marrow transplantation in two cases. At a median follow-up of 12 months, median CR duration and survival were 6 months and 17 months, respectively. Myelosuppression in the first course of induction therapy was moderate to severe. However, severe non-hematologic toxicity (WHO grade > or = 3) was characteristically rare. Although this is a preliminary study, the CAG combination seems promising for the treatment of relapsed AML, with its low toxicity contributing to a higher quality of life for the patient.

Aclarubicin↗
PubMed1995

[Comparison of low-dose cytosine arabinoside and aclarubicin in combination with granulocyte colony-stimulating factor to intermediate-dose cytosine arabinoside and mitoxantrone with or without etoposide in the treatment of relapsed acute myeloid leukemia].

We used a new chemotherapy regimen for the treatment of 18 consecutive patients with relapsed AML. The regimen consisted of low-dose cytosine arabinoside (Ara-C), low-dose aclarubicin and concurrent use of G-CSF (CAG regimen). Fifteen out of 18 patients (83%) achieved complete remission (CR). Median CR duration and median survival were 6 months and 15 months, respectively. These results were similar to those of previously reported salvage therapies for relapsed AML including intensive chemotherapy consisting of intermediate-dose Ara-C and sequential mitoxantrone with or without etoposide (MC/MEC), which we previously adopted. Myelosuppression and non-hematological toxicities were apparently lower and less frequent compared to MC/MEC. The CAG regimen seems promising for the treatment of relapsed AML with its low toxicity contributing to a high quality of life for the patient.

Aclarubicin↗