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Biomedical subjects

K Nakai

Publications and source records attributed to K Nakai.

At least 163 records · Page 9Linked to original sources
PubMed1997

The effect of endovascular therapy for cerebral arterial spasm, its limitation and pitfalls.

PURPOSE: The effect of endovascular treatment for vasospasm was investigated by analysing the results of patients treated in Wakayama City in 1994. MATERIALS AND METHODS: Ninety nine patients with ruptured cerebral aneurysms, who survived more than one week and were treated in Wakayama City in 1994, were studied. Twenty five patients caused symptomatic vasospasm and 25 were treated by endovascular therapy, percutaneous transluminal angioplasty (PTA) and/or intra-arterial papaverine infusion (IAP). PTA was performed for proximal vasospasm which located in the main arterial trunk, such as ICA, M1, BA (n = 3). IAP was chosen for distal vasospasm which located mainly in the M2, A1, A2 (n = 12). PTA and/or IAP was performed for diffuse vasospasm which located in proximal and distal arteries (n = 10). RESULTS: In the proximal vasospasm group, all patients were good to moderately disabled on the Glasgow outcome scale (GOS). In the distal vasospasm group, 8 patients were good to moderately disabled, and 4 patients were severely disabled. The overall results were as follows: 17 (68%), good to moderately disabled, 4 (16%), severely disabled, 4 (16%), dead. The morbidity and mortality rate was 8/25 (32%) in symptomatic spasm group. CONCLUSION: PTA was very effective especially for proximal vasospasm, but IAP was not always effective for distal or diffuse vasospasm. Diffuse vasospasm revealed a high mortality rate in spite of the endovascular therapy.

Adult↗
PubMed1997

Is unilateral spatial neglect a single phenomenon? A comparative study between exploratory-motor and visual-counting tests.

The aim of this study is to report the preliminary findings of a traditional battery of tests and our original battery capable of assessing the presence of components and extent of lesions in patients with unilateral spatial neglect. Thirty patients who had unilateral spatial neglect with a stroke in the right hemisphere were assessed for unilateral spatial neglect on exploratory-motor (E-M) tasks, visual-counting (V-C) tasks, and traditional neglect batteries at least 4 weeks after the onset. Other neuropsychological tests and computed tomography were also performed to investigate the relationship with neglect. A factor analysis showed that our tasks loaded significantly on three factors. E-M neglect was found in 16 patients, and V-C neglect in 22 patients with unilateral spatial neglect. There were high correlations between E-M neglect and motor paralysis, word fluency, backward digit span and motor impersistence. There were high correlations between V-C neglect and visual-field defect, line bisection, line cancellation and figure copying. Lesions in the frontal lobe, caudate, insula, and anterior portion of the paraventricular white matter were commonly associated with E-M neglect. Lesions in the occipital lobe were also associated with V-C neglect. We suggest that unilateral neglect is not a single phenomenon, but rather involves several different components. We propose that E-M and V-C tasks are useful methods for evaluating the extent of lesions in patients with unilateral spatial neglect.

Adult↗
PubMed1997

Predictors of sinus rhythm restoration after Cox maze procedure concomitant with other cardiac operations.

BACKGROUND: There have been sporadic cases of persistent atrial fibrillation and sick sinus syndrome after the maze procedure. The purpose of this study was to identify the predictors of sinus rhythm restoration after operation. METHODS: Between March 1993 and June 1995, we evaluated retrospectively 96 consecutive patients who underwent the maze procedure (maze III) in combination with another type of cardiac operation. Four patients who died and 6 patients who required permanent pacemaker implantation because of sick sinus syndrome were excluded. Ambulatory electrocardiographic monitoring was evaluated 1 year after operation. Multiple logistic regression analysis was applied to identify the predictors of sinus rhythm restoration. RESULTS: The final population comprised 86 patients (mean age, 59.8 years; 67 patients with mitral valve disease). Overall, sinus rhythm was restored in 68 of 86 patients (79.1%). The magnitude of the atrial fibrillatory wave positively predicted postoperative sinus rhythm restoration. Conversely, left atrial diameter was inversely related to postoperative sinus rhythm restoration. The odds ratio of having both a fine atrial fibrillatory wave (< 1.0 mm) and enlarged left atrial diameter (> or = 65 mm) for patients with sinus rhythm restoration was 0.04 (95% confidence interval, 0.01 to 0.28). CONCLUSIONS: Atrial fibrillatory wave and left atrial diameter were independent predictors of sinus rhythm restoration after the maze procedure in patients with chronic atrial fibrillation and organic heart disease.

Adult↗
PubMed1997

Cerebral angioplasty in a patient with vascular dementia.

A 66-year-old man with a history of previous transient ischemic attacks had progressive memory and gait disturbance caused by severe stenoses of both the internal carotid arteries and vertebral arteries. The patient underwent percutaneous transluminal angioplasty of the vertebral arteries and endarterectomy of the internal carotid arteries with satisfactory results. On admission, the patient was alert, but disoriented to time and place. He exhibited mild motor weakness in both legs. Neuropsychological tests revealed remarkable intellectual deterioration and he required maximum support to perform activities of daily living. Higher cortical function and the ability to perform activities of daily living improved remarkably after the angioplasty. Angioplasty is an alternative therapy to reverse functional deficits in patients with cerebrovascular hemodynamic compromise.

Aged↗
PubMed1997

Effects of structural modulation on biological activity of bombesin analogues with (E)-alkene bond.

The specific bombesin receptor antagonist, (E)-alkene bombesin isostere (EABI-1), [D-Phe6,Leu13psi[(E)CH=CH]Leu14]bombesin(6-14) is a potent antagonist in terms of inhibition of bombesin-stimulated amylase release from rat pancreatic acini. This study examined the effects of EABI-1 (L-L diastereomer) and three novel bombesin analogues on amylase release in rat pancreatic acini. EABI-2 is a L-D diastereomer of EABI-1. EABI-3 is an analogue, of which leucine at position 13 of EABI-1 was replaced with valine. EABI-4 is a L-D diastereomer of EABI-3 (L-L). The order of agonist potency was EABI-2>EABI-3>EABI-4. EABI-1 showed no agonist activity at concentrations up to 100nM. On the other hand, all of four analogues had antagonist activity. The order of antagonist potency was EABI-1>EABI-3>EABI-4>EABI-2. EABI-1 was a complete antagonist, EABI-2 and EABI-3 were partial agonists, and EABI-4 had a weak agonist effect. The present study provides a useful information on the future development of peptide analogues for anticancer agents and biological tools for investigating actions of bombesin family peptides.

Amylases↗
PubMed1997

Shear stress-induced myosin association with cytoskeleton and phosphorylation in human platelets.

Upon platelet activation by a high shear stress (108 dyne/cm2), actin and actin-binding protein increased rapidly into the Triton-insoluble cytoskeleton, whereas the association of myosin increased gradually. The amounts of cytoskeleton-associated myosin depended on the extent of aggregation. Preceding the maximal aggregation and ATP secretion, the 20 kDa light chain of myosin (MLC) is rapidly phosphorylated to approx. 45% of 20 kDa MLC and is then dephosphorylated. Cytoskeletal association of myosin and phosphorylation of 20 kDa MLC was inhibited by OP-41483, a prostaglandin I2 analog, which inhibited the full aggregation response to shear stress. Exposure to high shear stress resulted in an increased association of myosin light chain kinase and protein phosphatase types 1 and 2A with the cytoskeleton, while the cytoskeletal association of protein kinase C was not evident. These results indicate that 20 kDa MLC phosphorylation is involved in shear stress-induced platelet activation, and that cytoskeletal association of protein phosphatases may regulate the phosphorylation level of cytoskeletal elements such as myosin together with myosin light chain kinase.

Blood Platelets↗
PubMed1997

Rehabilitation of patients with anosognosia for hemiplegia due to intracerebral haemorrhage.

We have studied the differences in the lesions, concomitant symptoms and ADL levels in patients in acute-stage cerebral-haemorrhage and manifesting anosognosia. Twelve of 50 patients (24.0%) presented with anosognosia. The (+) group had longer intervals between onset and the first evaluation than did the (-) group, demonstrating severe sensory disturbance. The volume of haemorrhage was significantly larger in the (+) group. Anosognosia disappeared within 3 months in all cases. In the (+) group the time until discharge was long, with the ADL level at the time of discharge being low. Therefore, it was considered that anosognosia was important as an inhibitory factor hampering rehabilitation.

Activities of Daily Living↗
PubMed1997

Impairment of short-term memory in left hemispheric traumatic brain injuries.

We report on two patients with traumatic lesions in the temporal and parietal lobes who demonstrated disturbances of short-term memory (STM) following improvement on the aphasia. Patient 1 was a 66-year-old right-handed man who presented to our hospital with a cerebral contusion. One admission we observed a Wernicke's aphasia with paraphasic jargon in this patient that resolved within 8 weeks. Patient 2 was a 35-year-old right-handed woman, with an acute subdural haematoma and a cerebral contusion, who underwent craniotomy and evacuation of the haematoma. In this patient we noted a transient Wernicke's aphasia following the operation that improved within 3 months. Linguistically, the aphasia observed in each of these two patients was not a typical conduction aphasia because of the absence of paraphasia, and impairment of comprehension was unclear despite a decrease in performance on repetition tasks. Both verbal and non-verbal tasks suggested an impairment in STM. These findings suggest that involvement of the left hemisphere may cause disturbances in both verbal and non-verbal STM.

Adult↗
PubMed1997

Exploratory-motor task to evaluate right frontal lobe damage.

An exploratory-motor (E-M) task was performed by 20 patients with right hemispheric damage and unilateral spatial neglect and by 15 adult controls. None of the subjects in the control group demonstrated E-M neglect, other types of unilateral spatial neglect, or motor impersistence. In the unilateral spatial neglect group, 14 of 20 patients revealed E-M neglect. The presence or absence of E-M neglect related to word fluency, digit span recall (backward), and motor impersistence. In addition, E-M neglect frequency was observed in patients with lesions in the frontal lobe. The frontal lobe may play an important role in the performance of an E-M task. Therefore, we think that E-M task performance is a useful method for evaluating the site of right frontal lobe damage.

Adult↗
PubMed1997

Subdural and meaningful involvement related to Wegener's granulomatosis: case report.

OBJECTIVE AND IMPORTANCE: The first case of Wegener's granulomatosis associated with subdural empyema is presented. CLINICAL PRESENTATION: A 37-year-old man was admitted to our hospital for treatment of bilateral subdural masses. Magnetic resonance imaging demonstrated strong bilateral subdural and meningeal enhancement. The patient was treated with subdural drainage, based on the diagnosis of bilateral subdural hematoma or empyema as revealed by magnetic resonance imaging. Even after surgery, he developed systemic symptoms that are typical for Wegener's granulomatosis, including hemosputum, papules, peripheral nervous disorders, hematuria, myalgia, and joint pain. A diagnosis of Wegener's granulomatosis was confirmed by positive circulating antineutrophil cytoplasmic antibodies and histological findings from the skin and nasal mucosa. We diagnosed the subdural masses as Wegener's granulomatosis from the laboratory and neuroimaging studies, retrospectively. INTERVENTION: Pus-like fluid containing hematoma with negative micro-organism was evacuated by surgery. CONCLUSION: Wegener's granulomatosis should be suspected in young patients with pulmonary symptoms and subdural hematoma without head injury. This is the first case of Wegener's granulomatosis associated with subdural masses.

Adult↗
PubMed1997

Electrocardiographic nature of restored sinus rhythm after Cox maze procedure in patients with chronic atrial fibrillation who also had other cardiac surgery.

OBJECTIVE: To characterise heart rate variability and high frequency components of restored sinus rhythm after the maze procedure. The maze procedure for chronic atrial fibrillation may prevent thrombotic events and improve the quality of life. However, the electrocardiographic nature of restored sinus rhythm after the maze procedure has not been fully elucidated. PATIENTS AND METHODS: Between March 1993 and August 1995, 104 consecutive patients undergoing the maze procedure in combination with other cardiac surgery were studied. There were 100 long-term survivors (78 with mitral valve disease, 9 with aortic valve disease, 8 with congenital heart disease, and 5 others). Twenty age-matched patients with mitral valve disease who were in normal sinus rhythm preoperatively were enrolled as a control group. 30 days after surgery, the presence of arrhythmias and the circadian changes of heart rate variability were estimated by ambulatory electrocardiographic monitoring and the filtered P duration was evaluated by signal-averaged electrocardiogram. RESULTS: Restoration of sinus rhythm was observed in 73 of 100 cases. Subjects were classified into three groups according to their postoperative ambulatory electro-cardiographic monitoring findings: patients in group 1 (n = 73) (1a: 58 regular sinus rhythm; 1b: 15 sinus rhythm with frequent premature atrial contractions (> 1000/day); patients in group 2 (n = 21) still had persistent atrial fibrillation; and patients in group 3 (n = 6) required permanent pacemaker implantation because of sick sinus syndrome. The success rate of restoration of sinus rhythm was 88.3% if left atrial diameter was small (< 65 mm). Circadian changes in the low frequency to high frequency power ratio in group 1a were significantly diminished compared with control group (P < 0.01). Furthermore, the filtered P duration in group 1a (150 (20) ms) and group 1b (158 (23) ms) were longer than in the control group (122 (11) ms) (P < 0.01). CONCLUSIONS: The maze procedure may result in a decreased sinus response and non-uniform transmission of impulses in the atrium.

Adult↗
PubMed1997

Transplantation of autologous sympathetic ganglion into the brain with Parkinson's disease. Long-term follow-up of 35 cases.

Transplantation of autologous sympathetic ganglion was performed in 35 patients with Parkinson's disease. Approximately half the patients showed improvement of parkinsonian symptoms over the 3 years following transplantation. The patients showed amelioration of bradykinesia and gait disturbance, but tremor and muscle rigidity were not improved by transplantation. The other half of the patients did not show amelioration after transplantation. No serious complications were encountered, though mild ptosis was observed in all patients. The mechanism of improvement of symptoms might be the release of dopamine from the grafted sympathetic ganglion. Transplantation of autologous sympathetic ganglion can be a therapeutic modality for Parkinson's disease.

Adult↗
PubMed1997

Prediction of Mitochondrial Targeting Signals Using Hidden Markov Model.

The mitochondrial targeting signal (MTS) is the presequence that directs nascent proteins bearing it to mitochondria. We have developed a hidden Markov model (HMM) that represents various known sequence characteristics of MTSs, such as the length variation, amino acid composition, amphiphilicity, and consensus pattern around the cleavage site. The topology and parameters of this model are automatically determined by the iterative duplication method, in which a small fully-connected HMM is gradually expanded by state splitting. The model can be used to predict the existence of MTSs for given amino acid sequences. Its prediction accuracy was estimated to be 86.9% using the cross validation test. Furthermore, a higher correlation was observed between the HMM score and the in vitro ATPase activity of MSF, which can be regarded as an experimental measure of signal strength, for various synthetic peptides than was observed with other methods.

Journal Article↗
PubMed1997

[Syringomyelia appearing in a short term after brain abscess].

We describe a rare case of syringomyelia that developed within only 4 months after the cure of the focal cerebritis and abscess. An 18-year-old man who had suffered from meningitis and brain abscess 1.5 years before, presented with pain and sensory disturbance in his left shoulder. Magnetic resonance image (MRI) showed a syrinx formation extending from the upper cervical to the lower thoracic cord. Investigation by MRI during the course of the brain abscess had the appearance of posterior cerebellar arachnoid cyst 3 months after the onset of brain abscess and syrinx developed within 9 months. After posterior fossa decompression and reopening of the Magendie's foramen, his symptom and MRI abnormality improved after one month. In contrast to reported cases of syringomyelia following cerebritis, syrinx formation in our case appeared in relatively a short time. We speculated that basal arachnoiditis and the formation of posterior cerebellar arachnoid cyst caused syrinx formation in a short term after cerebritis.

Adolescent↗
PubMed1997

[Dural arteriovenous fistula presenting as acute-onset dementia: a case report].

We report here a unique case of acute-onset dementia caused by a posterior fossa dural arteriovenous fistula (AVF), which was successfully treated by surgical resection of the isolated transverse-sigmoid sinus combined with endovascular procedures. A 70-year-old female was admitted to our hospital with acute-onset dementia and pulsatile tinnitus on the left side. CT scan revealed a low-density area in the parieto-temporal region. Cerebral angiography revealed a dural AVF of the transverse-sigmoid sinus with retrograde drainage into cerebral cortical veins. After transarterial endovascular embolization of the dural AVF, a xenon-CT scan revealed increased cerebral blood flow. Four months postoperatively, however, she was admitted to our hospital again with seizure and aphasia due to recanalizaion of the dural AVF. After trans-arterial embolization, transvenous embolization was attempted, but was unsuccessful due to inaccessibility of the isolated sinus segment. Since this patient could not be cured by endovascular embolization, an open surgical resection of the isolated sinus segment was performed. Following this, CT scans revealed that the low density area present on the first admission had disappeared. The patient's dementia resolved postoperatively. We discuss the pathophysiological mechanism by which venous ischemia due to dural AVF can cause reversible dementia.

Acute Disease↗
PubMed1997

[Spontaneous intracranial hypotension with severe headache and typical neuroradiological findings: report of two cases].

Intracranial hypotension causes the postural headache that sometimes follows lumbar puncture. When postural headache and associated symptoms occur after lumbar puncture, the diagnosis is usually obvious. However, similar symptoms may occur after minor trauma or without an obvious precipitating cause (spontaneous intracranial hypotension: SIH). SIH is rare, but is now increasingly recognized as a cause of postural headache. We encountered two cases of SIH showing typical neuroradiological findings. Case 1 is a 47-year-old man who was admitted with severe frontalgia. CT scan revealed vague visualization of bilateral Sylvian fissures and slit ventricles. Spinal fluid pressure was 6cm H2O in the lateral recumbent position. Cerebrospinal fluid (CSF) showed slight lymphocytic pleocytosis. We treated him as having viral meningitis. His headache improved gradually and he was discharged 2 weeks later with slight occipitalgia. One week after discharge, he complained of severe headache again and plain CT showed bilateral subdural hematoma. The subdural hematoma in both sides was evacuated and his headache improved after the operation. Follow-up CT scans two months later showed normalization of ventricle size and cisterns. Case 2 is a 52-year-old woman who was admitted with severe occipitalgia. CT scan on admission showed slit ventricles and the disappearance of the suprasellar cistern and the Sylvian fissure. Spinal fluid pressure was 3cm H2O. Gd-enhanced MRI showed remarkable meningeal enhancement and effacement of the optic chiasm suggesting brain sagging. Her headache improved 2 weeks later after strict bed rest and oral pain relief drugs. The follow-up MRI showed disappearance of abnormal meningeal enhancement and normalization of optic chiasma effacement. SIH is one of the important differential diagnoses of patients complaining of postural headache. Meningeal enhancement of gadolinium-enhanced MRI is an important finding to diagnose SIH. We have to consider SIH when diagnosing postural headache.

Brain↗
PubMed1997

Better prediction of protein cellular localization sites with the k nearest neighbors classifier.

We have compared four classifiers on the problem of predicting the cellular localization sites of proteins in yeast and E. coli. A set of sequence derived features, such as regions of high hydrophobicity, were used for each classifier. The methods compared were a structured probabilistic model specifically designed for the localization problem, the k nearest neighbors classifier, the binary decision tree classifier, and the naïve Bayes classifier. The result of tests using stratified cross validation shows the k nearest neighbors classifier to perform better than the other methods. In the case of yeast this difference was statistically significant using a cross-validated paired t test. The result is an accuracy of approximately 60% for 10 yeast classes and 86% for 8 E. coli classes. The best previously reported accuracies for these datasets were 55% and 81% respectively.

Algorithms↗