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Biomedical subjects

T Yonehara

Publications and source records attributed to T Yonehara.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Brain embolism associated with atrial septal aneurysm].

We studied the clinical significance of atrial septal aneurysm on brain embolism. Of two-hundred twenty-eight consecutive ischemic stroke patients, 128 cases were performed transesophageal echocardiography to find cardiac lesions that could be embolic sources. Three cases were diagnosed as having atrial septal aneurysm with right-to-left shunt demonstrated by contrast echocardiography under Valsalva maneuver. These cases were all diagnosed as brain embolism from clinical courses and findings from brain CT scan, and cerebral angiography. Neurosonologic study, 24 hours Holter ECG, and transthoracic echocardiography did not reveal any other embolic sources. Paradoxical embolic mechanism is supposed to have occurred in these cases. Atrial septal aneurysm often coexists with right-to-left shunt and is clinically significant as a finding suggesting paradoxical embolism.

Aged↗
PubMed1997

[A case of vertebral artery dissection with lateral inferior pontine syndrome and lateral medullary syndrome].

A 55-years-old woman had left neck pain and headache, dizziness, left Horner's sign, left abducens palsy, diplopia, left peripheral facial palsy, left loss of hearing, left tinnitus, left paralysis of vocal cord and soft palate, dysphagia, left limb ataxia, truncal ataxia, disturbance of temperature and pain sensation over Th10 on the right involving the right face. Left vertebral angiography revealed tapering occlusion of the left vertebral artery. Right vertebral angiography showed normal angiogram of the basilar artery and bilateral anterior inferior cerebellar arteries. MRI disclosed infarcts in the left lateral inferior pons, left lateral medulla, and cerebellum of territories in the anterior inferior cerebellar artery and posterior inferior cerebellar artery. T2 weighted image showed septum (intimal flap) in the left vertebral artery. This is the very rare case of lateral inferior pontine syndrome and lateral medullary syndrome due to the vertebral artery dissection.

Aortic Dissection↗
PubMed1997

[Cerebral embolism due to lone atrial septal aneurysm].

A 71-year-old man was admitted to our hospital because of headache and left hemiparesis. Brain CT scan showed hemorrhagic infarction of the right frontal lobe. Intravenous digital subtraction angiography revealed no occlusion of cerebral arteries. No arrhythmias were observed by the holter ECG. Transthoracic echocardiography showed no abnormalities. Anticoagulation therapy (heparin and warfarin) was started under the diagnosis of cerebral embolism without definite embolic source and there was no recurrence during following four years. Transesophageal echocardiography showed an atrial septal aneurysm (ASA) without patent foramen ovale. A potential cause of cerebral embolism due to atrial septal aneurysm is paradoxical embolization through an interatrial shunt (patent foramen ovale). It was speculated that ASA was a direct source of thrombus formation in this case (lone ASA). Transesophageal echocardiography should be performed to find atrial septal aneurysm in patients with cryptogenic stroke, especially embolic stroke without definite embolic sources.

Aged↗
PubMed1996

[Dysphagia following lateral medullary infarction].

We studied 10 patients with lateral medullary infarction. Six patients had severe dysphagia from the onset, and needed tube feeding or intravenous hyperalimentation. Three of these 6 patients resolved dysphagia within 3.5 months. Pharyngoesophagography showed aspiration and pooling in the pharynx in other three patients who showed persisting dysphagia for more than 6 months. The cause of dysphagia was not unilateral paralysis of the pharynx and the larynx. Because there were decreased functions of elevation of the larynx, closure of the vocal cord and the pharyngeal movement, the dysphagia of our patients may be due to disturbance of the neurogenic swallowing control. Persistent dysphagia was associated with anterolateral extension of the infarction in the medulla. Two patients with laryngectomy and permanent tracheostomy were able to be discharged to home. We conclude that surgical treatment is a choice in patients with dysphagia which persists for more than 6 months.

Aged↗
PubMed1996

[A case of cerebral infarction due to dissection in a branch of the middle cerebral artery].

A 65-year-old man developed left drop hand, dysarthria and emotional incontinence. Brain CT and MRI revealed multiple cerebral infarctions in the cortex and subcortical white matter of the right temporal and parietal lobes which were in the distribution of the right middle cerebral artery. Cerebral angiography disclosed segmental narrowing (string sign) and two pseudoaneurysms in the right angular artery which were diagnosed as dissecting aneurysm of a branch of the middle cerebral artery. In this case, cerebral angiography was more useful than MRI in diagnosis of dissecting aneurysm of a branch of the middle cerebral artery. This was a very rare case of dissecting aneurysm of the middle cerebral artery localized in one of its branches.

Aged↗
PubMed1995

Neurologic features of chronic minamata disease (organic mercury poisoning) and incidence of complications with aging.

To elucidate the neurologic features of chronic Minamata disease, and the incidence of complications with aging, we studied 80 patients with documented Minamata disease (organic mercury poisoning) from 1986 to 1994 (mean age: 63 years). Of the cardinal neurologic findings, sensory impairment was seen with highest frequency in 98.8% of patients limited to the extremities in 86.3%. Impairment of lower extremity coordination was observed in 60%, constriction of the visual field in 51.9%, and retrocochlear hearing loss in 41%. To assess age-related complications, patients were separated into three groups by age: Group I (10 to 39 years); Group II (40 to 69 years); Group III (> or = 70 years). The incidences of hypertension and cerebrovascular diseases, organic ophthalmologic disorders (including cataracts), presbyacusis, and cervical spondylosis deformans increased significantly with age. Compared with a preceding survey (1981 to 1985, 171 patients, mean age: 63.5 years), the incidences of complicated hypertension and cataracts had decreased, whereas those of cerebrovascular disease and retinitis pigmentosa remained unchanged. The incidences of abnormal brain computed tomography (CT), presbyacusis, cervical spondylosis deformans, and positive tests for urine sugar also increased. The incidences of these complications other than retinitis pigmentosa were similar to those in the general population. These results accurately reflect the recent epidemiological disease tendencies in Japan toward a decreased incidence of hypertension and an increased incidence of diabetes.

Adolescent↗
PubMed1995

[A case of the brainstem tactile hallucinosis due to pontine hemorrhage].

A 53-year-old man with hypertension was admitted to our hospital, for somnolence, horizontal gaze palsy, right hemiparesis and right sensory disturbance. Brain CT scan revealed a high density area from the left lower pontine tegmentum to the left tegmentum of the lower midbrain. As he became alert, he reported visual hallucination. Two weeks after onset of stroke, he complained tactile hallucination on his right half body with sensory disturbance. After disappearance of the visual hallucination, the tactile hallucination had been persisted. This is the first report of peduncular hallucinosis with long-persisted tactile hallucination due to brainstem bleeding. Tactile hallucination was suggested to be associated with sensory disturbance and extensive destruction of the brain stem tegmentum.

Cerebral Hemorrhage↗
PubMed1994

Role of nitric oxide in the peripheral vessels of patients with familial amyloidotic polyneuropathy (FAP) type I.

In order to establish the generation of endothelial derived relaxating factor (EDRF) in patients with familial amyloidotic polyneuropathy (FAP) type I, the muscle temperature of the lower limb was measured with a deep portion thermometer. The temperature of the gastrocunemius muscle in FAP patients was significantly decreased compared with control subjects. In order to investigate the generation of EDRF in FAP patients, we administered NG-monomethyl-L-arginine (L-NMMA), specific inhibitor of nitric oxide, from the brachial artery and measured the changes in blood flow. Although 61.7 +/- 18.2% of the blood flow was transiently decreased after administration of L-NMMA in control subjects, FAP patients showed poor responses. In contrast, in the same way as in control subjects, significant vasodilatation was seen in FAP patients after administration of L-arginine. The urinary secreted NO2-/NO3- levels per day, which reflect the synthesis of nitric oxide in the systemic circulation, was a great deal lower in FAP patients than in control subjects. These results suggest that, although peripheral vessels can be dilated when a large amount of the substrate for NO synthase, L-arginine, is supplied, production of nitric oxide may be suppressed, and, as the result of this phenomenon, blood flow is decreased in the peripheral tissues of FAP patients in a static state.

Adult↗
PubMed1994

Role of superoxide dismutase and nitric oxide on the interaction between brain and systemic circulation during brain ischemia.

To elucidate the critical role of superoxide dismutase (SOD) and nitric oxide in brain injury and systemic circulation during brain ischemia, we performed bilateral carotid artery ligation (BCAL) on rats and evaluated the effects of NG-monomethyl-L-arginine (L-NMMA) and a long-acting SOD derivative (SMA-SOD). After administration of L-NMMA, specific inhibitor against nitric oxide synthase (NOS), most of BCAL rats died within 6 h while no BCAL rats without L-NMMA died at all. Administration of SMA-SOD exhibited no effect on the life span of BCAL rats. Magnetic resonance imaging (MRI) and microscopic analysis for the ischemic brain revealed that, although administration of L-NMMA showed no significant effect on the ischemic brain of BCAL rats, SMA-SOD effectively prevented the ischemic changes based on permeability edema in the frontal lobe. Measurement of changes in the blood flow of the ischemic brain revealed that administration of L-NMMA decreased the blood flow in the BCAL rats while no remarkable changes were seen after administration of SMA-SOD. Urinary secretion of NO2-/NO3-, the metabolites of nitric oxide, was increased by challenging BCAL, and the presence of L-NMMA or SMA-SOD diminished this elevation. Blood pressure was increased by performing BCAL to rats, and administration of L-NMMA showed further elevation of the blood pressure. On the contrary, administration of SMA-SOD decreased post-ischemic hypertension. These results suggest that SOD may play a protective role for brain ischemia by suppressing increased vascular permeability, while nitric oxide showed beneficial effect on the ischemic brain by increasing the blood flow in the ischemic brain.

Amino Acid Oxidoreductases↗
PubMed1994

High-level ATP production by a genetically-engineered Candida yeast.

Previous studies of ATP production with the methylotrophic yeast, Candida boidinii, suggested that the phosphorylation of AMP catalyzed by adenylate kinase (ADK) was rate-limiting. To investigate whether the enhancement of ADK activity in C. boidinii cells would improve ATP productivity, the Saccharomyces cerevisiae ADK1 gene encoding ADK was expressed in C. boidinii under the C. boidinii AOD1 promoter. Methanol-induced transformants had 10,000-fold enhanced levels of ADK activity and produced 23-fold more ATP from adenosine when compared to the control, parent strain. In a pH-controlled reaction system with successive adenosine-feeding, the ATP concentration in the reaction mixture reached 230 mM (117 g/l) over 45 hours, and was easily purified with an overall yield of 78 percent.

Adenosine Kinase↗
PubMed1994

Detection of reverse flow by duplex ultrasonography in orthostatic hypotension.

BACKGROUND AND PURPOSE: The aim of this study is to elucidate the effect of orthostatic hypotension on changes in cerebral blood flow. METHODS: Blood flow velocities of both the common carotid artery and vertebral artery were measured using duplex ultrasonography in 12 patients: 6 with familial amyloidotic polyneuropathy, 3 with Shy-Drager syndrome, 2 with pandysautonomia, and 1 with senile orthostatic hypotension. Simultaneously, peripheral blood flow was also evaluated by laser-Doppler flowmetry. RESULTS: The patients showing dizziness or syncope when tilted to a 70 degrees upright position exhibited characteristic reverse flow at the end-diastolic phase on the Doppler flow image of both the common carotid and vertebral arteries, which was effectively treated by infusion of 2.5 micrograms/min norepinephrine for 10 minutes. This end-diastolic reverse flow was not seen in any patients who did not have dizziness or syncope. After subjects were tilted from a supine to a 70 degrees upright position, decrease in the peripheral blood flow of the patients with orthostatic hypotension remained unchanged for at least 5 minutes, whereas that of control subjects was recovered within 2 minutes. However, no significant difference between the patients with and without clinical symptoms was observed. CONCLUSIONS: These results suggest that detection of this specific echographic pattern may be quantitatively useful in examination of clinical symptoms accompanying orthostatic hypotension and that duplex ultrasonography may be a helpful tool to evaluate the effect of drugs used for controlling these clinical signs.

Adult↗
PubMed1994

Recurrent embolization during intravenous administration of tissue plasminogen activator in acute cardioembolic stroke. A case report.

Treatment with recombinant tissue plasminogen activator (rt-PA) has been applied in acute cardioembolic stroke to reopen the occluded vessel and improve the patient's neurologic deficit. However, the effect of this therapy on intracardiac thrombus has not been documented previously. A forty-five-year-old man with dilated cardiomyopathy developed acute cardioembolic stroke with disturbance of consciousness, right hemianopia, right hemiplegia, and global aphasia. Cerebral angiography demonstrated occlusion of the left middle cerebral artery trunk. Intravenous administration of 30 megaunits (MU) of recombinant tissue plasminogen activator was commenced two hours after the ictus and completed within sixty minutes. Cerebral angiography was repeated just after this treatment and demonstrated a new occlusion of the left intracranial internal carotid artery along with occlusion of a branch of the left external artery. The authors subsequently performed two-dimensional echocardiography and found a mobile thrombus in the left ventricle. In patients with intracardiac mobile thrombi, recombinant tissue plasminogen activator seems to accelerate breakup or detachment of the thrombi and subsequent recurrent embolization. Therefore, it seems better to pay attention to the presence of mobile intracardiac thrombus before commencing intravenous infusion of rt-PA.

Acute Disease↗
PubMed1994

Treatment of a Japanese patient with familial amyloidotic polyneuropathy with orthotopic liver transplantation.

A 28-year-old male patient with familial amyloidotic polyneuropathy (FAP) underwent a liver transplantation from a heart-beating cadaveric donor in Sweden. He had suffered from the disease for 2.5 years. It took 5.5 hours to carry out the operation without blood transfusion. After the liver transplantation, serum amyloidgenic variant transthyretin (TTR) levels became extremely low and diarrhea stopped after the 7th day. On day 13, the patient was discharged from the hospital and one month after the transplantation, his general condition remained quite good. This is the first case of a Japanese patient with congenital metabolic disorders as well as FAP to receive a liver transplantation from a heart-beating cadaveric donor.

Adult↗
PubMed1993

Low plasma apolipoprotein AII levels in human and mouse amyloidosis with mutant transthyretin (Met-30) gene.

We measured the serum apolipoprotein levels in patients with familial amyloidotic polyneuropathy (FAP). The serum apolipoprotein AII levels were much lower than those of the control subjects, while the levels in asymptomatic carriers of the FAP gene were normal. Other plasma apolipoprotein levels, such as apolipoproteins AI, B, CII, CIII, and E, were all within normal ranges. The decrease of apolipoprotein AII in the plasma of FAP patients correlated with the progression of the disease. In a transgenic mice model of FAP carrying human variant transthyretin gene (Met-30), serum apolipoprotein AII levels were decreased in 1.5-year-old mice compared with control mice, while the 3-month-old mice had normal levels. These results suggest that apolipoprotein AII may play an important role in lipid metabolism or amyloid formation in patients with FAP.

Adult↗
PubMed1992

Bilateral medial medullary infarction with oculomotor disorders.

BACKGROUND AND PURPOSE: We describe the first case of bilateral medial medullary infarction demonstrated by magnetic resonance imaging. We discuss the relation between this lesion and the oculomotor signs that were observed clinically. CASE DESCRIPTION: A 71-year-old man initially presented with pure motor hemiparesis, which progressed to complete quadriplegia. He also developed nearly complete vertical and horizontal ophthalmoplegia. Magnetic resonance imaging revealed upper medial medullary infarctions bilaterally that extended to the pontomedullary junction. CONCLUSIONS: We propose that the vertical oculomotor disorders resulted from involvement of the oculomotor system in the caudal brain stem, especially the caudal paramedian pontine reticular formations on both sides.

Aged↗
PubMed1992

[Intracellular pH of surface epithelial cells and the movement of bicarbonate ions under acid-base imbalance in gastric mucosa].

To investigate the effect of the acid-base imbalance on the gastric mucosal defense mechanism, the intracellular pH of gastric surface epithelial cells were measured with double-barreled H+ selective microelectrodes in the isolated antral mucosa of bullfrog stomach. By knowing the intracellular pH and the PCO2 of the serosal perfusate, the intracellular HCO3- concentration was estimated, and the rate of HCO3- secretion was directly measured with the pH-stat method in mounted preparations on a Ussing's chamber. Both the calculated intracellular HCO3- concentration and the rate of HCO3- secretion were dependent on the exogenous HCO3- supplied from the serosal perfusate. The alkaline tide raised the intracellular HCO3- concentration, thus increasing the mucosal buffering power against acid. Under mild respiratory acidosis, the production of endogenous HCO3- from the serosal CO2 was enhanced, and both the intracellular HCO3- concentration and the rate of HCO3- secretion were increased. As a result, the intracellular pH was maintained at a physiologically optimal level, and the ability of gastric mucosal protection was strengthened by enrichment of cellular bicarbonate supply. It is confirmed in this study that the maintenance of acid-base status in the cell is indispensable in the protection of gastric mucosa against acid invasion.

Acid-Base Imbalance↗