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Biomedical subjects

S Hirai

Publications and source records attributed to S Hirai.

At least 127 records · Page 7Linked to original sources
PubMed1998

Eccentric roller type total artificial heart designed for implantation.

In the process of developing a completely implantable total artificial heart system, we have made an eccentric roller type total artificial heart and evaluated it by means of a mock circulatory system and by an acute animal experiment. The actuator of the artificial heart consists of 2 cylindrical drum type rollers which squeeze 2 blood chambers. The blood chambers are made of silicone rubber and are torus in shape. There is no valve used in this artificial heart. The artificial heart appears to be a nearly circular cylinder, approximately 10 cm in length and 8 cm in diameter. In the Donovan mock test, the artificial heart worked at a roller speed of 100-125 rpm with flow rates of 2.5-3.0 L/min for the right side and 3.2-3.8 L/min for the left side, respectively. The electric power consumption was 19.0-24.7 W. Our artificial heart is characterized by an ejection of blood alternatively in the pulsatile mode without need for reversing the motor. In the ex vivo evaluation, circulation of an adult sheep was maintained with this artificial heart for 4 h.

Animals↗
PubMed1998

Campylobacter fetus subspecies fetus cellulitis associated with bacteremia in debilitated hosts.

Campylobacter fetus subspecies fetus rarely causes celluitis associated with bacteremia in debilitated hosts. We have identified this infection in two patients with systemic lupus erythematosus and in one with liver cirrhosis. All three patients had eaten raw beef, liver, or improperly cooked pork before the manifestations of the illness. C. fetus subspecies fetus was recovered from blood and feces from the three patients. This organism was also isolated from a subcutaneous aspirate of the cellulitis lesion in one patient. DNA macrorestriction endonuclease profiles analyzed by pulsed field gel electrophoresis differed for the isolates from the three patients but were identical for the blood and fecal isolates or the aspirate and fecal isolates from each patient. These findings suggest that cellulitis associated with bacteremia arises from ingestion of C. fetus subspecies fetus organisms and that clinicians and microbiologists should be aware of this infection in debilitated hosts.

Adult↗
PubMed1998

[13C]-urea breath test for assessment of cure of Helicobacter pylori infection at 1 month after treatment.

Although the [13C]-urea breath test has been reported to provide high specificity and sensitivity, its reliability in determination of cure, including when and how the assessment of cure is made, is not fully established. Here we evaluate the reliability of judgment of cure after 1 month of therapy using the [13C]-urea breath test, including the appropriate time to assess its cure. Our subjects were 199 H. pylori-infected patients (144 men and 55 women; 50.5+/-0.76 years) who underwent cure therapy, took the breath test at 1 month, and underwent both the breath test and invasive tests using endoscopy at 6 months after completion of therapy. Accuracy of the breath test in judgment of cure at 1 month was investigated by comparing the results at 1 month with those at 6 months when cut-off value of the breath test was set at 5 per thousand. Chronologic alterations of the delta13C value were also analyzed in cured patients who underwent the breath test at 1, 3, and 6 months. In 167 (94.9%) of 176 patients whose breath test values were less than 5 per thousand, cure was reconfirmed at 6 months. In 14 (60.9%) of 23 patients whose values were greater than 5 per thousand, cure was demonstrated at 6 months. The mean delta13C values of 33 cured patients who took the breath test at 1 month and repeated the breath test at 3 and 6 months for any reasons were 4.14+/-0.74 per thousand, 2.02+/-0.23 per thousand, and 1.72+/-0.19 per thousand, respectively, and the value at 3 months was significantly smaller than that at 1 month. The reliability of assessment of cure by only the breath test at 1 month was sufficiently high (94.9%) once the patients were judged to be cured. However, because the breath test at 1 month yielded a high false-positive rate and the breath test values at 3 and 6 months were similar, evaluation of cure of H. pylori infection by the [13C]-urea breath test should preferably be done at 3 months after treatment to minimize false-positive results, or the concept of a borderline group should be established for patients with positive but relatively high delta13C values (5-10 per thousand) who repeated the breath test 3 months after treatment.

Breath Tests↗
PubMed1998

Loss of cholinergic synapses on the spinal motor neurons of amyotrophic lateral sclerosis.

The expression of vesicular acetylcholine transporter (VAChT) was examined immunohistochemically in the cholinergic synapses on the spinal motor neuron of the patient with sporadic amyotrophic lateral sclerosis (SALS). VAChT immunoreactive synapses were depleted on surviving motor neurons in SALS, while synaptophysin immunoreactivity was undiminished on the same neurons. This discrepancy suggests that in SALS, loss of cholinergic input on lower motor neurons is an early event, and may be part of the cause of death of those motor neurons.

Acetylcholine↗
PubMed1998

Decreased myocardial accumulation of 123I-meta-iodobenzyl guanidine in Parkinson's disease.

The aim of this study was to evaluate 123I-meta-iodobenzyl guanidine (123I-MIBG) myocardial scintigraphy in patients with Parkinson's disease as a way of detecting cardiac sympathetic dysfunction, and comparing the stage of disease and intensity of drug treatment with accumulation of 123I-MIBG. 123I-MIBG myocardial scintigraphy was performed in 48 patients with Parkinson's disease and 25 control subjects. In the planar imaging studies, the data acquisition matrix was 256 x 256 and the preset time was 5 min. The heart-to-mediastinum (H/M) average count ratio was calculated for both early (15 min) and delayed (3-4 h) images after 123I-MIBG injection (111 MBq). The mean H/M ratio in patients with Parkinson's disease was significantly lower than that in the controls (P < 0.0001). Regardless of disease severity, intensity of anti-Parkinson treatment and the presence or absence of orthostatic hypotension, the mean H/M ratios were always low in the Parkinsonian patients. Parkinson's disease may result in a severe abnormality of cardiac sympathetic function which has not been detected by previous cardiovascular autonomic studies.

3-Iodobenzylguanidine↗
PubMed1998

Mitochondrial deoxyribonucleic acid 3256C-T mutation in a Japanese family with noninsulin-dependent diabetes mellitus.

Accumulating reports indicate a relationship between mitochondrial DNA mutation and impaired glucose-induced insulin secretion leading to a subtype of noninsulin-dependent diabetes mellitus. DNA from a 45-yr-old Japanese woman with noninsulin-dependent diabetes mellitus and muscle atrophy was isolated and studied for mitochondrial DNA mutations. We identified a mitochondrial DNA C-T heteroplasmic mutation at nucleotide position 3256. The mutation was located in the transfer ribonucleic acidLeu in a region conserved in evolution. Eight other members of her family were examined for the mutation. Six of them had the same mutation together with noninsulin-dependent diabetes mellitus, and one teenage boy had the mutation and impaired glucose tolerance. The other family member who did not have this mutation had normal glucose tolerance. The enzyme activity of the mitochondrial oxidative phosphorylation pathway in the muscle of the proband was measured. The enzyme activity was decreased in the proband, especially in complex I. This mutation might be responsible for the abnormal glucose metabolism.

Adolescent↗
PubMed1998

Serial magnetic resonance imaging of acute spontaneous thrombosis of a giant intracranial aneurysm--case report.

A 46-year-old female presented with decreased bilateral visual acuity due to an unruptured non-thrombosed giant aneurysm arising from the left internal carotid artery. After admission, acute thrombosis of the aneurysm occurred spontaneously. Her consciousness and visual acuity temporarily worsened. Serial T2-weighted magnetic resonance (MR) imaging showed the size of the low intensity area near the orifice increased, and the aneurysm ruptured thereafter. Trapping of the aneurysm with a high-flow bypass was performed. Serial MR imaging findings clearly demonstrated the intraluminal structure of the thrombosed giant aneurysm. The aneurysm grew in size after thrombosis. The enlarging signal-void area on T2-weighted MR images were indicative of aneurysmal rupture. MR imaging is quite helpful to evaluate the changes of intraluminal thrombosis and size in giant aneurysms.

Acute Disease↗
PubMed1998

Angioarchitecture related to hemorrhage in cerebral arteriovenous malformations.

A retrospective study was conducted to determine the angioarchitecture related to hemorrhage in patients with cerebral arteriovenous malformations (AVMs), who underwent conservative treatment and long-term follow-up. The average observation period was 9.3 years, and the annual bleeding rate was estimated at 3.6%. In all cases angiographic findings were reviewed in detail. The average AVM grade by Spetzler-Martin was 3.5. Higher bleeding rate was observed in large AVM (5.4%) compared with small (2.1%) or medium AVM (2.9%). Deep venous drainage (8.6%/year) was strongly correlated to hemorrhage. Concerning location of nidus, hemorrhage was frequently found in insular, callosal, and cerebellar AVMs. Venous ectasia, feeder aneurysm, and external carotid supply were commonly demonstrated on angiograms. Comparison of annual bleeding rate revealed that AVMs with intranidal aneurysm (8.5%) and venous stenosis (5.5%) had a high propensity to hemorrhage. Therapeutic strategy should be focused on these potentially hazardous lesions by the use of endovascular embolization or stereotactic radiosurgery, even if surgical resection is not indicated.

Adolescent↗
PubMed1998

Serum of Behçet's disease enhances superoxide production of normal neutrophils.

Using an MCLA-dependent chemiluminescence technique, we evaluated superoxide production by neutrophils isolated from 7 patients with Behçet's disease. After stimulation by phorbol myristate acetate, N-formyl-methionyl-leucyl-phenylalanine or opsonized zymosan, neutrophils from the patients produced significantly more superoxide than those from 20 controls. Pretreatment of control neutrophils with serum prominently enhanced superoxide production, and serum from Behçet's disease patients had a significantly greater effect than that from controls. These findings suggest that serum from patients with Behçet disease contains the priming factor(s) that can enhance enhanced superoxide production by neutrophils in response to stimulation.

Adult↗
PubMed1998

Basic and clinical studies on ApoE gene typing by line probe assay (LiPA) as a biological marker for Alzheimer's disease and related disorders: multicenter study in Japan.

The fundamental reagent capability and clinical significance of ApoE gene typing has been investigated. The result of each test shows that the reagent capability satisfied the expected standard. Four-hundred thirty-nine samples classified into three groups (Alzheimer's disease (AD), other types of dementia and nondementia) were measured to examine the clinical significance. The rate of epsilon 4 genotype of each group was 31.5%, 14.6%, 10.4%, respectively. The AD group had a higher rate than the other groups (p < 0.001). The measurement of ApoE genotype is suggested to be useful as one of the guidelines in the diagnosis of AD.

Age Factors↗
PubMed1998

Simple right atrial procedure for chronic atrial fibrillation with atrial septal defect and aortic valvular regurgitation in an elderly patient.

A right atrial separation procedure was performed to eliminate atrial fibrillation (AF) during concomitant repair of an atrial septal defect and aortic valve regurgitation in an elderly patient. This procedure consisted of a Y-shaped incision in the right atrium, followed by cryoablation of the tricuspid annulus and the atrial septum. Only excision of the left atrial auricular appendage was performed in the left atrium. Although this procedure was devised to eliminate chronic AF associated with a solitary atrial septal defect, it was effective to eliminate chronic AF associated with atrial septal defect and aortic valve regurgitation in an elderly patient.

Aged↗
PubMed1998

[Iodine-123-labeled meta-iodobenzylguanidine myocardial scintigraphy evaluation of Machado-Joseph disease].

Iodine-123-labeled meta-iodobenzylguanidine ([123I]MIBG), an analogue of guanetidine, is used as a tracer for evaluation of the function of sympathetic neurons. To investigate cardiac sympathetic function in Machado-Joseph disease (MJD), [123I] MIBG myocardial scintigraphy was performed in 12 patients with MJD and 20 controls. In planar imaging studies, the heart to the mediastinum of the average count ratio (H/M) was calculated for both early and delayed images. The mean values of H/M in delayed images of MJD was lower than those of controls (p < 0.01), but this did not correlate with duration of the illness. The mean values of H/M in MJD patients with abnormal sympathetic skin response (SSR) was lower than that with normal SSR (p < 0.05). The decrease of H/M in delayed image is more sensitive than abnormal SSR. The increase of heart rate after standing in the patients with low H/M was lower than those with normal H/M. Abnormal cardiac sympathetic function revealed by [123I]MIBG myocardial scintigraphy in MJD can be seen earlier than abnormal sudomotor system detected by SSR.

3-Iodobenzylguanidine↗
PubMed1998

Basic and clinical studies on the measurement of tau protein in cerebrospinal fluid as a biological marker for Alzheimer's disease and related disorders: multicenter study in Japan.

The development of a diagnostic marker for earlier and more accurate clinical diagnosis of Alzheimer's disease (AD) is essential to identify AD patients during life unequivocally. The purpose of this study was to investigate the basic performance and clinical significance of tau level measurement in the cerebrospinal fluid (CSF) using an enzyme-linked immunosorbent assay (ELISA) developed by Innogenetics. The ELISA system showed reliable reproducibility and good linearity. For clinical studies, the CSF samples from a variety of patients (n = 332) were examined. They were classified into the four groups: Alzheimer's disease (AD); neurodegenerative disease (ND); cerebrovascular diseases (VD); and a neurological control (NC) group. The CSF-tau levels for AD, ND, VD and NC were 426 +/- 234 pg/ml, 239 +/- 157 pg/ml, 216 +/- 136 pg/ml, and 188 +/- 103 pg/ml, respectively. The CSF-tau level of the AD group was significantly higher than that of the other groups (p < 0.001). The CSF-tau levels increased during follow-up. The measurement of the tau level in CSF is shown to be a useful marker to confirm a clinical diagnosis of AD.

Aged↗
PubMed1998

[Recent advances in Alzheimer's disease research].

Vascular dementia (VD) and Alzheimer's disease (AD) are two main causes of dementia in the aged. Recent epidemiological studies in Japan indicate that the incidence of AD is becoming slightly higher than that of VD. Among various approaches to clarify the etiology of AD, research through the mechanism of formation of senile plaque and neurofibrillary tangle, which characterize AD pathology, seems to be the most orthodox as well as fruitful. Genetic studies on hereditary AD reveal that the etiologies of AD are heterogeneous, but the deposition of beta amyloid followed by the accumulation of abnormally phosphorylated tau-protein seems to be the common process specific to AD. In regards to the clinical problems of AD, development of the diagnostic markers for early definite diagnosis and effective therapeutic agents is most urgent. The index of A beta 40/A beta 42 x tau calculated from measurements of A beta and tau levels in cerebrospinal fluid is the best marker at present. On the other hand, many antidementia drugs are now on trial. Most of them are acetylcholine stimulating agents, including tacrine and donepezil, which have been admitted recently in the USA and some other countries. Such drugs which suppress the development of AD should be called true antidementia agents, but the present drugs are not true antidementia drugs.

Alzheimer Disease↗
PubMed1998

Assessment of a new silicone tri-leaflet valve seamlessly assembled with blood chamber for a low-cost ventricular assist device.

We have developed a practical, low-cost ventricular assist device (VAD) comprising a newly designed blood chamber with a silicone lenticular sac and two silicone tri-leaflet valves (STV), made en bloc. This new VAD is seamless, can be made cost-effectively and assembled with the blood chamber and valve as one body. This novel design should reduce the incident of thrombus formation because of the absence of a junction at the connecting ring and because of the use of flexible silicone materials which have both antithrombogenecity and biocompatibility. In in vitro hemodynamics testing, a batch of 3 consecutively manufactured VADs with STVs underwent hydrodynamic functional testing. These showed less regurgitation, a lower value of water hammer phenomenon, and a slightly greater pressure gradient across the valves than a mechanical valve (MV) [Björk-Shiley monostrut valve]. The flow and pulsatile efficiency were adequate and similar to that of a VAD with MVs. In in vitro durability and hemolysis tests, a VAD with STV functioned well for 54 days and showed similar hemolytic profiles to a VAD with MVs. In an in vivo acute experiment using an adult sheep, our device was problem-free providing sufficient output as a left ventricular assist device (LVAD). Although it will be necessary to decrease the pressure gradient across this STV in the future, our device showed efficient performance as a practical land cost-effective VAD for short term use.

Adult↗
PubMed1998

Efficacy of a left atrial procedure for treatment of chronic atrial fibrillation in elderly patients.

A simple left atrial procedure for atrial fibrillation (AF) was performed in 16 elderly patients (age over 70 years old) with chronic AF associated with mitral and/or aortic valvular diseases. Chronic AF was eliminated upon discharge in 13 out of the 16 patients (81%). Twelve of the 13 patients (92%) whose AF had disappeared recovered the atrial kick of their right atrium, and 9 patients (70%) recovered the atrial kick of their left atrium. A simple surgical procedure to the left atrium was effective in the treatment of chronic AF associated with mitral valve disease in elderly patients. This simple procedure is preferable to other methods for the elimination of chronic AF with mitral valve disease in elderly patients.

Aged↗
PubMed1998

[Venous system playing a key role in transpetrosal approach].

A case with a large vertebrobasilar junction aneurysm developed a venous infarction in the temporal lobe after an operation using the transpetrosal approach. Although little of the literature has been concerned with venous complications after the transpetrosal approach, the case prompted us to study the venous system as playing a key role in the transpetrosal approach. Analyzing 30 carotid and 15 vertebral angiograms of 15 patients who underwent preoperative cerebral angiography using digital subtraction angiography (DSA), we investigated the venous system near the junction of the superior petrosal sinus, the transverse sinus and the sigmoid sinus (STS junction) which may play a key role in the transpetrosal approach. Drainage pathways of the superficial middle cerebral vein (SMCV) were classified into four types; sphenoparietal, sphenobasal, sphenopetrosal and undeveloped. In the sphenopetrosal type (4/30: 13%), the drainage of SMCV passes back along the floor of the middle fossa to drain into the transverse sinus. The lateral temporal vein (LTV) and the temporobasal vein (TBV) drain into the transverse sinus. The LTV emptied into the transverse sinus either directly (20/30: 67%) or indirectly through the tentorial sinus (10/30: 33%). The entry of the LTV into the transverse sinus (venous point) was usually located in the lateral third of the transverse sinus (14/20: 70%), but sometimes in the middle third (6/20: 30%). The TBV, observed in 8/30 (27%), also often emptied into the tentorial sinus to drain into the transverse sinus. Atresia of a unilateral transverse sinus and a large LTV emptying into the distal sigmoid sinus was observed in 2/15 cases. The venous system near the STS junction may be interrupted by the incision of the tentorium and the middle fossa dura mater and by the retraction of the sigmoid sinus. Since the transpetrosal approach may cause venous complication by compromising the venous system near the STS junction, it is necessary to evaluate of the venous system preoperatively using DSA and to set up a surgical strategy preserving the venous system.

Aneurysm↗