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Biomedical subjects

H Iida

Publications and source records attributed to H Iida.

At least 361 records · Page 20Linked to original sources
PubMed1991

Effect of the immunosuppressive agent, ciclosporin, on experimental immune complex glomerulonephritis in rats.

Effect of the immunosuppressive agent, ciclosporin (CS), on bovine serum albumin (BSA) nephritis in rats was evaluated. Eight weeks after immunization, 19 male Wistar rats received a daily intravenous dose of BSA (2 mg). Two weeks later, 11 rats received BSA and an oral dose of CS (10 mg/kg), and 8 rats received only BSA for 2 weeks. Urinary protein was measured weekly and serum anti-BSA antibody was measured by passive hemagglutination biweekly. The animals were killed at the 12th experimental week and blood samples and kidney specimens were obtained. BUN and serum creatinine were measured at the time of sacrifice. Kidney specimens were processed for light and immunofluorescent microscopic examination. Urinary protein excretion was significantly less in CS-treated rats than in nontreated controls at the 2nd week after treatment (5.3 +/- 1.3 vs. 25.6 +/- 10.3 mg/day, p less than 0.05). Anti-BSA antibody titers were lower in treated rats than in controls at the 2nd week after the treatment. There were no significant differences in the levels of BUN and serum creatinine between two groups. Glomerular hypercellularity and mesangial widening were milder in treated rats than in controls, and glomerular deposition of BSA was less intense in treated rats than in controls. These results suggest that CS suppressed the antibody production and the development of glomerular changes in rats with immune complex glomerulonephritis.

Animals↗
PubMed1991

Noninvasive quantification of regional myocardial blood flow in coronary artery disease with oxygen-15-labeled carbon dioxide inhalation and positron emission tomography.

BACKGROUND: Oxygen-15-labeled water is a diffusible, metabolically inert myocardial blood flow tracer with a short half-life (2 minutes) that can be used quantitatively with positron emission tomography (PET). The purpose of this study was to validate a new technique to quantify myocardial blood flow (MBF) in animals and to assess its application in patients. METHODS AND RESULTS: The technique involves the administration of 15O-labeled carbon dioxide (C15O2) and rapid dynamic scanning. Arterial and myocardial time activity curves were fitted to a single tissue compartment tracer kinetic model to estimate MBF in each myocardial region. Validation studies consisted of 52 simultaneous measurements of MBF with PET and gamma-labeled microspheres in nine closed-chest dogs over a flow range of 0.5-6.1 ml/g/min. A good correlation between the two methods was obtained (y = 0.36 + 1.0x, r = 0.91). Human studies consisted of 11 normal volunteers and eight patients with chronic stable angina and single-vessel disease, before and after intravenous dipyridamole infusion. In the normal group, MBF was homogeneous throughout the left ventricle both at rest and after administration of dipyridamole (0.88 +/- 0.08 ml/g/min and 3.52 +/- 1.12 ml/g/min, respectively; p less than or equal to 0.001). In patients, resting MBF was similar in the distribution of the normal and stenotic arteries (1.03 +/- 0.23 and 0.93 +/- 0.21 ml/g/min, respectively). After dipyridamole infusion, MBF in normally perfused areas increased to 2.86 +/- 0.83 ml/g/min, whereas in the regions supplied by stenotic arteries it increased to only 1.32 +/- 0.27 ml/g/min (p less than or equal to 0.001). CONCLUSIONS: PET with C15O2 inhalation provides an accurate noninvasive quantitative method for measuring regional myocardial blood flow in patients.

Animals↗
PubMed1991

Expression of smooth muscle cell phenotype by rat mesangial cells in immune complex nephritis. Alpha-smooth muscle actin is a marker of mesangial cell proliferation.

Mesangial cell proliferation is common in glomerulonephritis but it is unclear if proliferation is associated with any in vivo alteration in phenotype. We investigated whether mesangial of mesangial proliferative nephritis induced with antibody to the Thy-1 antigen present on mesangial cells. At day 3 glomeruli displayed de novo immunostaining for alpha-smooth muscle actin in a mesangial pattern, correlating with the onset of proliferation, and persisting until day 14. An increase in desmin and vimentin in mesangial regions was also noted. Immunoelectron microscopy confirmed that the actin-positive cells were mesangial cells, and double immunolabeling demonstrated that the smooth muscle actin-positive cells were actively proliferating. Northern analysis of isolated glomerular RNA confirmed an increase in alpha and beta/gamma actin mRNA at days 3 and 5. Complement depletion or platelet depletion prevented or reduced proliferation, respectively; these maneuvers also prevented smooth muscle actin and actin gene expression. Studies of five other experimental models of nephritis confirmed that smooth muscle actin expression is a marker for mesangial cell injury. Thus, mesangial cell proliferation in glomerulonephritis in the rat is associated with a distinct phenotypic change in which mesangial cell assume smooth muscle cell characteristics.

Actins↗
PubMed1991

Functional Golgi units in microtubule-disrupted cultured atrial myocytes.

We examined the effects of disassembly of microtubules (MT) on the structure and the functions of the Golgi apparatus (GA) in cultured atrial myocytes. MT disassembly with nocodazole led to fragmentation of the GA into small units. The fragmented Golgi units retained their cis-trans polarity and post-cisternal elements, including the trans-Golgi network (TGN). Neither endocytosis of lectin-labeled membrane nor its delivery to the fragmented Golgi units was interrupted by fragmentation of the GA after MT disassembly with nocodazole treatment. A fraction of the secretory granules associated with the fragmented Golgi units was also labeled with the internalized tracer. These results suggest that in nocodazole-treated cultured atrial myocytes, the fragmented Golgi units appear to be structurally and functionally intact despite the altered geometric arrangement of the GA in the cells.

Animals↗
PubMed1991

Two-dimensional and Doppler echocardiographic findings in a case of subaortic "fibrous sac".

We described a 37-year-old man with a subaortic "fibrous sac", admitted for congestive heart failure. On 2-dimensional echocardiography a saccular structure was seen to extend from the left coronary cusp of the aortic valve to the outflow tract of the left ventricle. By color Doppler imaging, a grade 3 aortic regurgitation was recognized. Aortic regurgitant flow was recorded from the left coronary cusp to the saccular lesion. When congestive heart failure became exacerbated, the repeat examination showed the regurgitant flow passing through the perforated bottom of this lesion and reaching the left ventricular cavity. On microscopic examination of the excised valve, capillary proliferation and inflammatory changes were recognized near the annular region of the left coronary cusp. The edge of the valve leaflet and the other 2 cusps were intact. It is likely that our patient had a mycotic aneurysm near the aortic ring. We speculate that aortic regurgitation followed inflammation. It dilated the left ventricular cavity and contributed to congestive heart failure. Inflammation also weakened the tissue near the annulus, causing it to protrude into the subaortic region thus forming a small aneurysm. It may have grown to become a large saccular structure under high aortic pressure. That is, it became a "giant" endocardial pocket with inflammatory process. Finally, the rupture of this sac caused a massive aortic regurgitation, exacerbating congestive heart failure.

Adult↗
PubMed1991

Assessment of superior vena caval blood flow velocity in ischemic heart disease.

In order to evaluate the right atrial function in patients with ischemic heart-disease, we studied the superior vena caval blood flow velocity using pulsed Doppler echocardiography. The subjects included 31 patients with anteroseptal infarction (ANT), 23 with inferior or inferoposterior infarction (INF + POS), 27 with effort angina pectoris (EAP) and 15 with vasospastic angina pectoris (VAP). The systolic peak flow velocity (PFVs) was significantly reduced only in INF + POS compared with those in ANT, EAP and VAP (36.8 +/- 1.8 cm/sec vs 46.9 +/- 2.1 cm/sec, 46.4 +/- 2.1 cm/sec and 42.6 +/- 1.9 cm/sec, p less than 0.05, respectively). No significant difference in diastolic peak flow velocity (PFVd) was found between the 4 groups. PFVs/PFVd was significantly reduced only in INF + POS compared with those in ANT, EAP, and VAP (1.39 +/- 0.05 vs. 1.75 +/- 0.08, 1.76 +/- 0.09, and 1.62 +/- 0.09, p less than 0.05, respectively). These results suggested that INF + POS caused impairment of the right atrial reservoir function.

Analysis of Variance↗
PubMed1991

Feasibility of intraoperative aortic root angiography in the identification of critical coronary lesions.

Early revascularization is critical for the treatment of acute myocardial infarction (AMI) because the ischemic myocardium begins to suffer irreversible damage after 4 h from the onset of symptoms. However, to make a diagnosis, perform coronary angiography, and prepare for operative revascularization usually takes longer than 4 h. Also, once a patient develops severe cardiogenic shock, coronary angiography is often impossible. Without angiography, the patient is no longer a candidate for surgical repair. To circumvent this problem, we designed this experiment to determine whether intraoperative aortic root angiography after cardiopulmonary bypass and cardioplegic arrest could satisfactorily substitute for angiographic examination in the identification of critical coronary lesions. The feasibility of this approach was tested in dog hearts in which one or tow of the major coronary arteries were ligated. The ascending aorta was then clamped, contrast material was injected, and continuous real-time fluoroscopic images were obtained and recorded on videotape. The videotape was then analyzed by three physicians independently, each without prior knowledge of the lesion locations. Lesions of the left anterior descending artery, the circumflex coronary artery, and the right coronary artery were identified with 94, 91, and 94% accuracy, respectively, for an overall identification rate of 92%. We conclude that aortic root angiography reliably demonstrates coronary artery lesions, and refinements in this technique may allow certain patients to undergo coronary operations without preoperative catheterization.

Angiocardiography↗
PubMed1991

Platelet-complement interactions in mesangial proliferative nephritis in the rat.

Complement has been reported to mediate mesangiolysis and glomerular hypercellularity in the rat in a model of glomerulonephritis (GN) induced with anti-Thy 1 antibody. To investigate the mechanism for the complement-mediated hypercellularity, the authors first determined if the effect of complement depletion was to inhibit cell proliferation or whether the effect was primarily to inhibit leukocyte infiltration. Rats depleted of complement with cobra venom factor (CVF) had 1) significantly less mesangiolysis than controls at day 5 (0.6 +/- 0.1 versus 3.4 +/- 0.4, scale 0-4+, P less than 0.001); 2) less cell proliferation, as assessed by immunostaining for the proliferating cell nuclear antigen (PCNA)/cyclin, a cell-cycle-dependent antigen (0.5 +/- 0.1 versus 2.4 +/- 0.7 cells/glomerular cross-section, P less than 0.01); and 3) less leukocyte infiltration as assessed by immunohistochemical labeling (0.6 +/- 0.1 versus 1.9 +/- 0.3 cells/glomerular cross-section, P less than 0.01). Because it was reported recently that platelets also mediate glomerular cell proliferation in this model, this study examined whether the mechanism for complement-mediated cell proliferation involved an effect on glomerular platelet localization. The glomerular uptake of 111In-labeled platelets was quantitated in normal and CVF-treated rats at 1, 4, 12, and 24 hours after induction of GN. Rats with anti-Thy 1 GN had substantial glomerular accumulation of platelets at all times studied, peaking at 4 hours (608 +/- 171 platelets per glomerulus). Complement depletion profoundly reduced glomerular platelet localization in anti-Thy 1 GN (mean less than 35 platelets per glomerulus at all times studied, P less than 0.05). Thus these studies demonstrate an important role for complement in mediating platelet localization in anti-Thy 1 GN, an effect that may account for the complement-dependent, neutrophil-independent glomerular hypercellularity in this model.

Animals↗
PubMed1991

[Midazolam as a premedicant for trigeminal nerve blocks].

Although patients with trigeminal neuralgia can be treated satisfactorily with nerve blocks, the block procedure is sometimes very painful and uncomfortable for them. To investigate the efficacy and adverse effects of midazolam as a premedicant for trigeminal nerve blocks, 19 patients were randomly assigned to receive either midazolam (0.05 mg.kg-1, n = 6), midazolam (0.1 mg.kg-1, n = 7), or saline/placebo (n = 6) before the block. The patients given midazolam (0.1 mg.kg-1) had a significantly lower incidence of recalling the block procedure and had complained of less discomfort when interviewed the following day. No serious adverse effects were observed in any patient given midazolam. Midazolam can be used safely as an effective premedicant for potentially uncomfortable procedures such as trigeminal nerve blocks.

Aged↗
PubMed1991

[The quantitative evaluation of myocardial blood flow and myocardial FDG uptake in the infarcted lesions with Q-wave and without Q-wave determined by O-15 water, FDG and PET].

Cardiac PET elicits an accurate relationship between myocardial blood flow (MBF) and tissue viability, which is evaluated by myocardial FDG uptake (MFU). To differentiate reversible tissue from necrotic tissue after the ischemic event, we from necrotic tissue after the ischemic event, we measured absolute MBF and MFU in patients with myocardial infarction. The MBF obtained by O-15 water and dynamic PET was accurately corrected by employing a tissue fraction (a) for the partial volume effect, including wall-motion effect. MFU was also corrected by using the tissue fraction. The subjects consisted of 5 patients with non-Q-wave infarction and 7 patients with Q-wave infarction. The regions of interest were selected from the infarcted area, each corresponding to regions with Q-wave or non-Q-wave. The MBFs in regions with Q wave (0.36 +/- 0.14 ml/min/g) were lower than those without Q wave (0.74 +/- 0.29 ml/min/g) (p less than 0.005). MFUs in regions without Q-wave (0.061 +/- 0.028) were higher than those with Q-wave (0.038 +/- 0.017) (p less than 0.05). The highest threshold of MBF in regions where Q-wave was detected was 0.55 ml/min/g. It is concluded that we will able to find the threshold of electrophysiological dysfunction in the infarcted region with this method.

Aged↗
PubMed1991

Sympathetic and renin-angiotensin system in conscious rabbits with two-kidney, one clip hypertension.

We attempted to clarify the contribution of the altered neural mechanism associated with increased angiotensin II to two-kidney, one clip (2K1C) hypertension on the 3rd and 35th days after renal artery stenosis. 2K1C hypertension was produced in 20 rabbits, and a sham operation was performed in 11 rabbits. Sarl, Ile8 angiotensin II (AIIA) infusion tests and baroreflex sensitivity determinations by bolus injection of phenylephrine were performed on the 3rd and 35th days after renal artery stenosis. The blood pressure was 12 mmHg higher in the hypertensive rabbits than in the sham operated rabbits on the 3rd day after clipping. The blood pressure returned to the control level during the infusion of AIIA. On the 35th day after clipping, AIIA-sensitive or AIIA-resistant hypertension developed. The blood pressure was higher in the AIIA-sensitive rabbits than in the AIIA-resistant rabbits (131 +/- 5 vs 116 +/- 4 mmHg, p less than 0.05). The baroreflex sensitivity was lower in the AIIA-sensitive rabbits than in the AIIA-resistant rabbits (1.8 +/- 0.3 vs 2.8 +/- 0.3 msec/mmHg, p less than 0.05). There was no difference in plasma norepinephrine between the two groups on either the 3rd or 35th day. Thus, impaired baroreflex sensitivity was found in the accelerated hypertension seen in the chronic phase of 2K1C hypertension. Neural mechanisms mediated by the peripheral sympathetic nervous system did not appear to contribute to the development of 2K1C hypertension.

Angiotensin II↗
PubMed1991

Rapid measurement of cerebral blood flow with positron emission tomography.

The intravenous administration of H2(15)O makes possible the quantitative evaluation of regional changes in cerebral blood flow (CBF) during various neuronal activations in man. Many variations on this technique have been proposed. We have compared bolus and slow administration procedures and short and long scan lengths. For a short scan period this study suggests that the bolus injection procedure (with a scan length of 60-120 seconds) provides better CBF count statistics and less sensitivity to errors in the input function than the slow infusion procedure. For a long scan length (greater than 3 min) the slow infusion procedure is recommended. Continuation of H2(15)O infusion allows prolongation of the scan length, which enables us to obtain sufficient CBF statistics (the statistical error may be negligibly small if a sufficient amount of H2(15)O is infused). Another advantage of the slow infusion method may be related to the fluctuation of CBF during the scan period. If CBF fluctuates during this period the slow infusion procedure is expected to provide an average estimate of CBF, whereas the bolus injection procedure provides an estimate (an average over 10 seconds) of CBF which is more sensitive to short-term variations. The feasibility of using 15O2 inhalation to measure regional CBF has also been investigated. By means of a dynamic H2(15)O scan which measures the regional distribution volume of water and a static C15O emission scan which measures blood volume prior to the 15O2 scan, both CBF and cerebral metabolic rate for oxygen (CMRO2) have been accurately measured by the 15O2 scan for various physiological conditions. The application of this technique in a human study confirmed the uncoupling of CBF and CMRO2 during motor and visual activation.

Autoradiography↗
PubMed1991

Optimization of H2(15)O-CBF method for higher signal-to-noise ratio.

We described theoretical principle and data analysis for PET study using intravenous H2(15)O for measurement of cerebral blood flow (CBF) with emphasis on stimulation study for psychophysiological test. In order to improve signal-to-noise (S/N) ratio in CBF images, we optimized the scan procedures and data analysis. We determined optimal scantime of autoradiographic image to provide minimum S/N ratio as to 90 through 120 sec. Increase of full-width at half-maximum (FWHM) of smoothing filter did reduce the image noise (standard deviation, SD) more rapidly than the partial volume effect. Phantom experiment showed a tendency that a larger FWHM provided a higher statistical t-value.

Brain↗
PubMed1991

[Non-supervised home exercise programs in a convalescent phase of acute myocardial infarction: their effectiveness and the usefulness of the heart rate at the anaerobic threshold].

The effectiveness of 2 different exercise programs in the convalescent phase of acute myocardial infarction (AMI) was assessed. One hundred and five patients with AMI were enrolled for one of these 2 non-supervised home exercise programs immediately after discharge from the hospital. Before discharge and one month later, they underwent submaximal graded treadmill exercise tests with the application of expiratory gas analysis. All patients were assigned to perform 2 km of walk-jog exercise daily for one month. The heart rate during exercise, duration of exercise and the total steps during 24 hrs were measured. Eighty patients (group A) underwent the exercise program in which their heart rates were maintained at 100-110 beats/min during exercise; while 25 patients (group B) underwent the other program in which their heart rates were maintained at 90-100% of those obtained at their anaerobic threshold (AT). The ventilatory AT was calculated by the standard technique using the Horizon System. In group A, AT increased from 13.4 ml/min/kg to 15.1 ml/min/kg (p < 0.01) after the exercise program and in group B, from 12.8 ml/min/kg to 14.9 ml/min/kg (p < 0.01). In group B, AT increased in all patients, while it remained unchanged in 30% of the patients in group A (p < 0.01). In conclusion, a non-supervised home exercise program can be effective and easily instituted for rehabilitation in a convalescent phase of AMI. The program using 90-100% of the heart rates at the anaerobic threshold seemed to be more suitable for obtaining better effects on exercise tolerance than that using 100-110/min heart rate.

Aged↗
PubMed1991

Optimal scan time of oxygen-15-labeled water injection method for measurement of cerebral blood flow.

We investigated the optimal scan time for obtaining the maximal signal-to-noise (S/N) ratio in cerebral blood flow (CBF) measured by PET imaging following 15O-water bolus injection. We performed sequential measurements with dynamic scans of six subjects injected at rest while listening to white noise. Each dynamic data set was edited into images corresponding to different scan times and were calibrated to CBF images by the table look-up method. For each scan time, we evaluated a pixel-by-pixel standard deviation of the CBF for sequential measurements. The S/N-ratio of CBF in the gray matter was 10.2 +/- 1.7 and 13.6 +/- 2.9 at a 40 and 120 sec scan time, respectively. The gain of the 120-sec over 40-sec scan time corresponds to an 80% increase in the number of trials to reach the same S/N-ratio in a stimulation-activation study. The simulation study supported the results, in which the maximal S/N-ratio of the CBF was demonstrated to be 90 and 120 sec at a CBF of 80 and 60 ml/100 ml/min, respectively. It is concluded that the optimal scan time of the 15O-water bolus injection method is in the interval from 90 to 120 sec.

Brain↗
PubMed1991

[New analysis algorithm for regional cerebral blood flow and partition coefficient with dynamic SPECT and N-isopropyl-p-[123I]iodoamphetamine: graphical plot method].

We developed a new analysis algorithm based on multiple-time graphical plot to estimate the regional cerebral blood flow and partition coefficient using dynamic SPECT and N-isopropyl-p-[123I]iodoamphetamine (123I-IMP). By assuming the 2-compartment model of the kinetic for 123I-IMP, we derived a linear relationship between the ratio of the tissue activity concentration at the times to the time-integral arterial concentration at the respective times (formula; see text) and the ratio of the time-integral tissue concentration to the time-integral arterial concentration (formula; see text), and demonstrated that the Y-intercept and X-intercept of the plot line represent the regional cerebral blood flow (K1) and partition coefficient (lambda), respectively. The slope of the line represents a clearance constant k2. The present method was applied to data on four normal subjects measured by dynamic SPECT. Values of the K1 and lambda for the gray matter were obtained 40.8 +/- 6.5 ml/100 g/min and 28.8 +/- 5.3 ml/g, respectively, and the corresponding values for the white matter were 29.1 +/- 4.7 ml/100 g/min and 28.1 +/- 7.1 ml/g. The new method enabled a rapid estimation of both K1 and lambda.

Algorithms↗
PubMed1991

Myocardial tissue fraction--correction for partial volume effects and measure of tissue viability.

We have compared two independent methods of correcting the systematic underestimation in measurements of myocardial radiotracer concentration due to wall motion and small transmural wall thickness in cardiac PET studies. The first technique was based on measurement of the tissue fraction by fitting 15O-labeled water dynamic PET data. The other technique involved the subtraction of the C15O-blood volume scan from the transmission data, producing an image of extravascular density. In normal myocardial regions, both values were observed to be about 60% of myocardial tissue density. The tissue fraction was approximately 10% larger than the extravascular density in normal tissue regions. The ratio of alpha/Dev indicates the proportion of the total extravascular tissue for a given ROI that is perfusable by water--independent of the partial volume effect. This ratio was confirmed to be the expected value in normal tissue regions but was reduced in regions of infarction. The use of 15O-water, C15O and transmission data may aid in the differentiation between perfusable and nonperfusable tissue in the infarcted myocardium.

Adult↗