Biomedical subjects

K Harada

Publications and source records attributed to K Harada.

At least 649 records · Page 36Linked to original sources

PubMed1994

Acidemia and hypernatremia enhance postischemic recovery of excitation-contraction coupling.

The purpose of the present study was to determine whether Na(+)-H+ and Na(+)-Ca2+ exchanges modulate postischemic recovery of excitation-contraction coupling. Experiments were performed in 43 isolated isovolumic dog hearts perfused with blood (pH 7.40, 141 mmol/L Na+, 34 degrees C, paced at 2 Hz). A 3 x 3-mm region at the left ventricular (LV) apex was loaded with aequorin for monitoring [Ca2+]i simultaneously with LV pressure. No-flow ischemia for 2 to 3 minutes was followed by 20 minutes of aerobic reperfusion with (1) unmodified control blood (141 mmol/L Na+, pH 7.40), (2) acidemic blood (141 mmol/L Na+, pH 6.60, at 0 to 3 minutes of reperfusion), (3) hypernatremic blood (149 or 157 mmol/L Na+, pH 7.40, at 0 to 20 minutes of reperfusion), or (4) hyperosmotic blood (141 mmol/L Na+ + 30 mmol/L mannitol, pH 7.40, at 0 to 20 minutes of reperfusion). Reperfusion with unmodified control blood was immediately followed by an increase in [Ca2+]i and LV systolic and diastolic pressure that persisted for 2 to 3 minutes before returning to or below baseline. Ventricular arrhythmia occurred during this period (> 80%). This transient increase of [Ca2+]i was attenuated by acidemic or hypernatremic perfusate. With acidemic or hypernatremic reperfusion, recovery of LV developed pressure at 20 minutes was more complete than with unmodified control reperfusion: acidemic blood (n = 7), 93 +/- 3% (P < .01); hypernatremic blood (149 mmol/L Na+, n = 7), 89 +/- 2% (P < .02); hypernatremic blood (157 mmol/L Na+, n = 4), 91 +/- 2% (P < .01); and unmodified control blood (n = 17), 80 +/- 2%. With hyperosmotic reperfusion, recovery of LV developed pressure at 20 minutes was not improved (82 +/- 3%). From these results we conclude that (1) an increase in intracellular Ca2+ occurs transiently after no-flow ischemia and may cause arrhythmia and decreased Ca2+ responsiveness of the contractile elements, (2) acidemic and hypernatremic reperfusion ameliorates postischemic dysfunction by preventing the increase in intracellular Ca2+, suggesting that (3) Na(+)-H+ and Na(+)-Ca2+ exchange may play important modulatory roles during reperfusion.

Animals↗

PubMed1994

Secretion-recapture process of apolipoprotein E in hepatic uptake of chylomicron remnants in transgenic mice.

To investigate the role of apoE in hepatic uptake of chylomicron remnants, we studied chylomicron metabolism in transgenic mice overexpressing apoE in the liver. Plasma clearance of injected 125I-labeled human chylomicrons was fivefold faster in transgenic mice than in controls. Immunohistochemistry demonstrated that apoE was specifically localized at the basolateral surface of hepatocytes from fasted transgenic mice. After injection of a large amount of chylomicrons, the density of the cell surface apoE was markedly reduced and vesicular staining was observed in the cytoplasm, suggesting that the cell surface apoE was used for hepatic endocytosis of chylomicrons and remnants. Polyacrylamide gel analysis of chylomicrons and remnants that had been reisolated from plasma and from liver membrane after the injection of chylomicrons showed the particles to be enriched with apoE mainly after their influx into the liver rather than during their residence in plasma. These results provide strong evidence for the secretion-recapture process of apoE, whereby chylomicron remnants enter the sinusoidal space, acquire apoE molecules, and subsequently are endocytosed. Data from experiments with very low density lipoprotein and LDL showed that this system is specific for chylomicron remnants.

Animals↗

PubMed1994

Basic fibroblast growth factor improves myocardial function in chronically ischemic porcine hearts.

The effect of basic fibroblast growth factor (bFGF) administration on regional myocardial function and blood flow in chronically ischemic hearts was studied in 26 pigs instrumented with proximal circumflex coronary artery (LCX) ameroid constrictors. In 13 animals bFGF was administered extraluminally to the proximal left anterior descending (LAD) and LCX arteries with heparin-alginate beads and 13 other animal served as controls. bFGF-treated pigs showed a fourfold reduction in left ventricular infarct size compared to untreated controls (infarct size: 1.2 +/- 0.4% vs. 5.1 +/- 1.3% of LV mass, mean +/- SEM, P < 0.05). Percent fractional shortening (% FS) in the LCX area at rest was reduced compared with the LAD region in both bFGF and control pigs. However, there was better recovery in the LCX area after rapid pacing in bFGF-treated pigs (% FSLCX/% FSLAD, 22.9 +/- 7.3%-->30.5 +/- 8.5%, P < 0.05 vs. prepacing) than in controls (16.0 +/- 7.8%-->14.3 +/- 7.0%, P = NS). Furthermore, LV end-diastolic pressure rise with rapid pacing was less in bFGF-treated than control pigs (pre-pacing; pacing; post-pacing, 10 +/- 1; 17 +/- 3; 11 +/- 1* mmHg vs 10 +/- 1; 24 +/- 4; 15 +/- 1 mmHg, *P < 0.05 vs. control). Coronary blood flow in the LCX territory (normalized for LAD flow) was also better during pacing in bFGF-treated pigs than in controls. Thus, periadventitial administration of bFGF in a gradual coronary occlusion model in pigs results in improvement of coronary flow and reduction in infarct size in the compromised territory as well as in prevention of pacing-induced hemodynamic deterioration.

Animals↗

PubMed1994

Genetic variation estimated in three Shorea species by the RAPD analysis.

Three species of Shorea (S. leprosula, S. acuminata and S. cursitii) were collected from a natural forest reserve of Malaysia and analyzed for genetic variation using the technique of random amplification of polymorphic DNA (RAPD) by the polymerase chain reaction (PCR). The average number of nucleotide substitutions was estimated. The nucleotide diversities within species were very similar and larger than those found in Drosophila melanogaster. The nucleotide divergences between these species are about 1.5 times the nucleotide diversities within the species, indicating that these species diverged from a common ancestor relatively recently.

Base Sequence↗

PubMed1994

Left ventricular contractile state of early human neonates with patent ductus arteriosus.

Using echocardiographic technique, we studied the left ventricular (LV) contractile state in 32 full-term infants within 24 hr after birth. They were divided into 2 groups based on the timing of the examinations; the group 1 (n = 17), < 3 hr after birth; the group 2 (n = 15), > 3 and < 24 hr after birth, and the additional examinations were performed on day 5. The patency of the ductus arteriosus and its internal diameter were determined by pulsed Doppler and two-dimensional echocardiography. The left atrial to aortic root ratio was obtained from M-mode echocardiography, and the LV contractile state was estimated by the relationship between heart rate-corrected velocity of circumferential fiber shortening (mVcfc) and end-systolic meridional wall stress (ESS). The ductus arteriosus was open in all cases of group 1 and in 83% of the cases of group 2, but the ductal diameter and the left atrial to aortic root ratio significantly decreased in group 2. The relationship between mVcfc and ESS showed no significant differences between 2 groups and the control. Afterload, represented as ESS, was significantly lower in group 1 than the control. We suggest that the low afterload condition helps the adequate LV contraction even under the increased preload through the left-to-right ductus arteriosus shunting after birth.

Blood Flow Velocity↗

PubMed1994

Right ventricular diastolic filling in the first day of life.

To evaluate the effects of altered preload on the Doppler flow pattern of right ventricular inflow in the first day of life, serial Doppler echocardiography of the pulmonary artery (PA) and tricuspid valve was performed in 16 normal neonates at 2, 12, and 24 hr. A computer-interfaced digitizer pad was utilized to measure the followings: PA flow velocity-time integral, total transtricuspid flow velocity-time integral, flow velocity-time integral of early diastolic filling (E area), and flow velocity-time integral of atrial contraction (A area). The PA flow velocity-time integral, total transtricuspid flow velocity-time integral, E area, A area, peak E, and peak A were increased significantly by 24 hr compared with the values at 2 hr of age. However, the peak E/A, E/A area and peak E/total transtricuspid flow velocity-time integral did not show significant changes from 2 to 24 hr. The ductus arteriosus size was inversely correlated with the peak E (r = -0.46, p < 0.05), E area (r = -0.37, P < 0.05), and A area (r = -0.34, p < 0.05). Therefore, the increase in right ventricular preload at 24 hr is considered to be due to the cessation of the left-to-right shunt through the ductus arteriosus. These results suggest that the pattern of early and late diastolic filling of the right ventricle were dependent on the increase in preload. We can therefore conclude that the redistribution of transtricuspid flow induced by the preload condition should be taken into account to interpret the transtricuspid velocity pattern in terms of diastolic function.

Blood Flow Velocity↗

PubMed1994

Hemoglobin Bethesda causing polycythemia in a Japanese family.

A family with Hemoglobin Bethesda is reported. A 23-year-old man was hospitalized for the evaluation of polycythemia. Analysis of hemoglobin using high pressure liquid chromatography showed the presence of hemoglobinopathy. Separation of globin into alpha and beta chains revealed approximately 50% of the beta chain to be abnormal. Analysis of the DNA sequence of the beta chain gene identified Hb Bethesda. The family study disclosed that his father and sister also had the same hemoglobinopathy. This case is the first report of Hb Bethesda in Japan.

Adult↗

PubMed1994

Quantitative assessment of influence of aging on optokinetic nystagmus.

A quantitative assessment of the influence of aging on optokinetic nystagmus (OKN) was investigated using 50 normal adults in ages ranging from 30 to 70 years. In linear stimulus-induced OKN, a statistically significant difference was demonstrated in slow-phase OKN velocity only between the 30-59 year old age group and the 70-79-year-old age group, when OKN stimulus was more than 60 degrees/s. Step stimulus-induced OKN was investigated in the same age groups in order to compare aging effects upon slow-phase OKN velocity. No statistically significant difference was found in slow-phase OKN velocity between younger age groups and the oldest age group. There was no significant difference in fast-phase velocity among the age groups. Thus, step-induced OKN has a wider clinical application than linear stimulus-induced OKN.

Adaptation, Physiological↗

PubMed1994

Rebound positional nystagmus as a peripheral origin.

Three cases of rebound positional nystagmus (RPN) are discussed in the present study. In all cases, spontaneous nystagmus was absent in the primary position, but positional nystagmus appeared in the side down position, and then nystagmus in the reversed direction appeared when the patient was returned to the primary position. The characteristics of RPN in the cases we studied were very similar to those of benign positional nystagmus. Tinnitus was accompanied with vertigo in Cases 2 and 3, and the glycerol tests were positive in Cases 1 and 3. There were no other abnormalities of ocular movements, neurological and neuroradiological examinations suggestive of central nervous system disorders indicating that RPN can be ascribed to peripheral lesions. A selective review of the literature is presented.

Electrooculography↗

PubMed1994

Role of the prepositus hypoglossi nucleus on primary position upbeat nystagmus.

Electrolytical destruction of the floor of the fourth ventricle was performed on 10 cats in order to produce primary position upbeat nystagmus (PPUN). In 5 cats who had unilateral lesions of the floor of the fourth ventricle, PPUN was never seen. Two of the remaining 5 cats, who had bilateral lesions, showed PPUN. In 2 cats with PPUN, the oculomotor level of the caudal fourth ventricle, in order that PPUN may be developed, it is necessary that the prepositus hypoglossi nucleus (PH) be destroyed bilaterally. The present experiment suggests that bilateral PH lesions could result in a tonic imbalance for eye positions and eye movements of the vertical axis, resulting in a downward drift with a corrective saccade; PPUN.

Animals↗

PubMed1994

The effect of uvulonodular lesions on horizontal optokinetic nystagmus and optokinetic after-nystagmus in cats.

The effect of uvulonodular lesions on horizontal optokinetic nystagmus (OKN) and optokinetic after-nystagmus (OKAN) was investigated in alert cats. A lesion in each of 6 cats was made by suction-ablation under anesthesia. In the 3 cats with only a uvular lesion, both the initial slow phase velocity and the time constant of OKAN were unchanged. In the remaining 3 cats whose lesions included the nodulus as well as the uvula, the time constant of OKAN was markedly prolonged, but the initial slow phase velocity of OKAN was not affected. The postoperative average time constant of OKAN increased from the normal value of 9 s to about 40 s. In contrast, OKN parameters (the steady-state velocity and the rising time constant) were not affected by uvular or uvulonodular lesions. These results strongly suggest that the nodulus is involved in the velocity storage mechanism and might control the discharge characteristics of the velocity storage integrator.

Animals↗

PubMed1994

Deltopectral flap for one-stage reconstruction of pharyngocutaneous fistulae following total laryngectomy.

Postoperative pharyngocutaneous fistulae are troublesome complications after total laryngectomy. To manage this complication, we devised an operative method consisting of a one-stage repair using a deltopectal flap. With this technique we can immediately cover both skin and pharyngeal defects. We have applied this method to 5 patients all of whom have successfully recovered their swallowing function.

Aged↗

PubMed1994

Intraoperative angiography in the resection of arteriovenous malformations.

Surgical resection of 13 operatively obscure arteriovenous malformations (AVM's) was accomplished with the assistance of intraoperative angiography, which was performed stereographically to provide three-dimensional orientation and was repeated until total resection of the AVM was confirmed. All films obtained were subtracted to improve clarity. The method presented here may be useful for the resection of all types of AVM. Only two patients had residual AVM after the initial operation. No complications attributable to angiography were noted.

Adolescent↗

PubMed1994

Establishment of enzyme-linked immunosorbent assays for lipoprotein lipase with newly developed antibodies.

We developed eight new antibodies against lipoprotein lipase (LPL), which included polyclonal antibodies raised against recombinant human LPL produced by transformant cells and two synthetic peptides corresponding to either amino (N)- or carboxy (C)-terminus of human LPL. With these antibodies, we established three effective sandwich enzyme-linked immunosorbent assays (ELISAs) for LPL, which enabled us to examine LPL mass not only in the postheparin plasma from human, rat, mouse, and guinea pig but also in the media and lysates of cultured cells. All of the developed antibodies showed high affinities for LPL, but their binding to LPL did not always influence the lipolytic activity of the enzyme. Interestingly, although the anti-C-terminus antibody should bind to a common epitope of human and mouse LPL, its binding selectively suppressed only human LPL activity. Because amino acid sequence surrounding the epitope is common to both LPLs, difference in the sequence outside the epitope will contribute to the selective suppression of LPL activity by the antibody. Our results also suggested that both termini of LPL would be exposed on the surface of the molecule because they were fully accessible to antibodies and that the N-terminus of LPL would be functionally less important because binding of the anti-N-terminus antibody did not affect human LPL activity. The ELISAs were further utilized to demonstrate the presence of C-terminus truncated LPL protein in the postheparin plasma of an LPL-deficient patient, to map an epitope of the anti-C-terminus antibody within residues 433-436, and to gain insight into the structure-function relationship of the LPL molecule.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

[A case of pontine hematoma with Foville's syndrome in childhood].

We reported a surviving case of 6-year-old boy with pontine hematoma. He complained of headache as an initial symptom and developed progressively Foville's syndrome with impairments of the IX-XII cranial nerves. Although brainstem tumor was suspected initially using CT scan, MRI revealed the existence of hematoma in the ventromedial pons. During the first 4 months of his clinical course, Gd-DTPA did not demonstrate any enhancement in that lesion. However, hemangiomatous lesion was suspected by subsequent serial MRIs with positive Gd-DTPA enhancement. Using conservative treatment including oral corticosteroids, all the neurological deficits disappeared in several months and he did not show any recurrence of clinical signs for 3 years. It was suggested that MRI was very useful in the differential diagnosis and the follow-up of hematoma in the posterior fossa.

Accessory Nerve↗

PubMed1994

[Evaluation of cerebro-vascular diseases with persistent carotid-basilar anastomosis].

Five cases of cerebro-vascular diseases with carotid-basilar anastomosis were evaluated. Case 1: a 73-year-old female was diagnosed as having subarachnoid hemorrhage due to a ruptured aneurysm of the right internal carotid artery-posterior communicating artery bifurcation and demonstrated that a left proatlantal intersegmental artery. Case 2: a 38-year-old female showed intraventricle hemorrhage due to arteriovenous malformation and showed left primitive hypoglossal artery. Case 3: 73-year-old female was diagnosed as having subarachnoid hemorrhage due to a ruptured basilar top aneurysm and demonstrated that a right primitive hypoglossal artery. Case 4: a 29-year-old male with unruptured aneurysm of the left internal carotid artery-posterior communicating artery bifurcation, and right trigeminal artery was detected incidentally by magnetic resonance angiography (MRA). Furthermore, right proatlantal intersegmental artery was detected by conventional angiography. Case 5: a 76-year-old male was diagnosed as having subarachnoid hemorrhage due to a ruptured aneurysm of the anterior communicating artery. MRA showed the aneurysm and a primitive trigeminal artery. No clinical symptom related with carotid-basilar anastomosis was detected. Magnetic resonance angiography (MRA) was useful for diagnosis of asymptomatic carotid-basilar anastomosis. Especially, axial view of MRA by time of flight method detected two cases of a primitive trigeminal artery. And coronal view of MRA by phase contrast method is useful for diagnosis of primitive proatlantal intersegmental artery. More asymptomatic persistent carotid-basilar anastomosis may be detected by MRA.

Adult↗

PubMed1994

[Vitreous hemorrhage after accidental head injury with chest compression--case report].

Vitreous hemorrhage is relatively common following subarachnoid hemorrhage, but rarely occurs after accidental head injury. In this paper, we report a rare case of vitreous hemorrhage after an accidental head injury with chest compression. A 4-month-old girl was held in her father's arms. After he fell down, she struck her head and her chest was compressed by her father's body. She soon became pale and was immediately transported to our center complaining of disturbance of consciousness on February 6, 1993. On admission, she was semicomatose and had a generalized convulsion. Computed tomography (CT) scan showed a subdural hematoma, although no fracture was detected on the plain X-ray film. Bilateral vitreous hemorrhage was also observed. The anterior fontanelle pressure was a high 330 mmH2O. The patient was treated conservatively with agents to promote hemostasis and reduce the intracranial hypertension. She was discharged after one month with normal consciousness and improved vision. The follow-up CT scan revealed subdural hematoma, hemorrhagic infarction (suggesting rupture of the pontine veins), and cerebral atrophy, corresponding to those of the shaken baby syndrome. Her chest was compressed by her father's body. The anterior fontanelle pressure was a high 330 mmH2O. These findings suggest that shaking or abrupt deceleration, acute intrathoracic hypertension and acute intracranial hypertension, caused retinal hemorrhage, and that extensive retinal hemorrhage possibly resulted in vitreous hemorrhage.

Craniocerebral Trauma↗

PubMed1994

Pseudolipoma of Glisson's capsule. Report of six cases and review of the literature.

We report six cases of pseudolipoma of Glisson's capsule. The patients ranged from 53 to 83 years old (mean 67.7 years), and all were men. Pseudolipoma of Glisson's capsule was detected by imaging studies before operation in two cases, and noted incidentally in the remaining four. Computed tomography demonstrated a subcapsular low-density nodule with or without a high-density spot. All but one patient had a history of abdominal operation. Grossly, the pseudolipoma was a solitary encapsulated nodule on the surface of the anterior aspect in five, and posteroinferior to the right lobe in one. The pseudolipomas ranged from 0.5 to 2 cm in diameter, were white to yellowish-white and elastic-firm. Histologically, the nodules had a dense fibrous capsule and contained necrotic mature fat tissue. In addition, three showed focal calcification. Blood vessels were rarely found within the capsule. These findings strongly suggest that history of abdominal operation, advanced age, sex, and poor blood supply to the nodule are causal to their development. Although only 18 cases have been reported previously, our six cases during but a 3-year period suggests that it may not be as rare as believed.

Adipose Tissue↗