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Biomedical subjects

N Handa

Publications and source records attributed to N Handa.

At least 73 records · Page 4Linked to original sources
PubMed1994

Asymptomatic carotid lesions and silent cerebral infarction.

BACKGROUND AND PURPOSE: Few studies have investigated the relationships between asymptomatic carotid lesions and silent infarcts confirmed on magnetic resonance imaging. METHODS: A consecutive series of 117 subjects (average age, 62 +/- 9.4 years) who were free from neurological deficit but had at least one established risk factor for stroke were investigated by B-mode carotid ultrasonography and magnetic resonance imaging of the brain. Carotid lesions were evaluated by plaque score, maximum percent stenosis, and the existence of ulcerated lesions. The relations between the carotid lesions and the incidence, size, or localization of the brain lesions were investigated. RESULTS: The incidence of silent infarcts was 42% in all subjects and significantly increased with advancing age (P < .05). Most lesions were smaller than 1 cm in diameter and were usually localized in the subcortical white matter or the basal ganglia. The percentage of subjects with infarcts increased significantly as the plaque score increased (P < .05) or when subjects had high-grade stenosis (P < .05) or ulcerated lesions (P < .01). These relationships were also noted in each decade of age. A higher incidence of larger lesions (> 1 cm) was found in the brain hemisphere ipsilateral to the carotid lesion, particularly in subjects with high-grade stenosis or ulcerated lesions (P < .01). Multivariate analysis indicated significant correlations with silent infarcts for age, hypertension, and plaque score. CONCLUSIONS: Both the severity and characteristics of asymptomatic carotid lesions estimated by B-mode ultrasonography were closely related to the appearance of silent infarcts. These results demonstrate that noninvasive assessment of carotid lesions can be useful in predicting the existence of silent cerebral infarction even in patients free from neurological deficits.

Adult↗
PubMed1994

Paradoxical embolism as a cause of ischemic stroke of uncertain etiology. A transcranial Doppler sonographic study.

BACKGROUND AND PURPOSE: This study was designed to test the hypothesis that paradoxical embolization would be a cause of embolic strokes and transient ischemic attacks in patients with stroke of uncertain etiology in all age groups. METHODS: Thirty patients who had stroke of uncertain etiology were studied. They were divided into the following three groups: 13 patients with sudden onset (group A), 11 patients with subacute onset (group B), and 6 asymptomatic stroke patients (group C). Eleven patients with stroke of obvious etiology (group D) and 11 normal healthy volunteers (group E) were also studied as controls. In all patients transcranial Doppler sonography and contrast echocardiography were recorded simultaneously after intravenous injection of the contrast medium. Findings of positive patient foramen ovale in contrast echocardiography or "chirp" sounds in transcranial Doppler sonography were defined as positive for paradoxical contrast embolization. Radioisotope phlebography of the lower extremities and pulmonary scintigraphy, using technetium-99 macroaggregated albumin, were performed in all 17 patients who had positive findings of paradoxical contrast embolization and in 12 patients whose findings were negative. RESULTS: Positive findings of paradoxical contrast embolization were found in 17 subjects by transcranial Doppler sonography but in only 8 on contrast echocardiography. These positive findings were detected more frequently in group A (77%) than in groups B, D, and E (9%, 18%, and 9%, respectively) (P < .05). In group C, 4 of 6 patients (67%) had positive findings. There were positive findings on both phlebography and pulmonary scintigraphy only in 6 group A patients, with positive findings of paradoxical contrast embolization. CONCLUSIONS: Transcranial Doppler sonography is a sensitive detector of right-to-left shunts. Paradoxical cerebral embolization might be frequent in patients with stroke of unknown etiology, especially when the stroke is of sudden onset.

Adult↗
PubMed1994

[Therapeutic effect of lisuride maleate on post-stroke depression].

Twenty post-stroke depressive patients who obtained more than 11 points on Self-Rating Questionnaire for Depression, were treated with 0.075 mg/day lisuride maleate for 12 weeks. The drug effect on depression was evaluated quantitatively by the Hamilton Rating Scale for Depression. The relationships between brain CT or MRI and SRQ-D score were investigated in 24 subjects. More than 80% of post-stroke depressive patients improved after lisuride maleate treatment for 8 or 12 weeks. In particular, depressed mood, hypobulia, sleep disturbance, anxiety, etc. were significantly improved compared to the baseline condition. As for the relationships with CT and/or MRI findings, the group with moderate to severe brain atrophy had a significantly higher grade of depressive state than those without.

Aged↗
PubMed1994

Reactivity of cerebral blood flow to carbon dioxide in hypertensive patients: evaluation by the transcranial Doppler method.

OBJECTIVE: To evaluate hypertensive cerebral involvement before cerebrovascular accidents. DESIGN: Cerebral microvascular responses to changes in the arterial partial pressure of CO2 (pCO2; the CO2 reactivity) were compared among patients with different stages and severity of hypertensive disease. PATIENTS: Fifty-eight patients with hypertension, 11 with borderline hypertension, 15 hypertensives with cerebral infarction and 58 normotensive controls were studied. METHODS: The cerebrovascular CO2 reactivity was determined by measuring simultaneously the end-tidal pCO2 and the blood flow velocity in the middle cerebral artery using transcranial Doppler sonography under hypocapnic, normocapnic and hypercapnic conditions. RESULTS: CO2 reactivity was impaired in the hypertensive patients compared with in the normotensive controls, but less so than in the symptomatic hemisphere of the hypertensive patients with cerebral infarction. The CO2 reactivity in the borderline hypertensive patients was greater than that in both the symptomatic and asymptomatic hemispheres of the hypertensive patients with cerebral infarction. In the subjects without cerebral infarction, two risk factors for cerebral atherosclerosis (age and hypertension) were negatively correlated with cerebrovascular CO2 reactivity. In the hypertensive patients age and the estimated duration of hypertension were negatively correlated with cerebrovascular CO2 reactivity. CO2 reactivity in the patients with hypertensive or arteriosclerotic retinopathy or ST-T changes on their electrocardiogram was impaired compared with that in the patients without such changes. CONCLUSIONS: Hypertension affected the microvascular reactivity of the brain before the development of cerebrovascular accidents, and its effect varied dependently on the extent of involvement of other target organs.

Adult↗
PubMed1994

Split dose iodine-123-IMP SPECT: sequential quantitative regional cerebral blood flow change with pharmacological intervention.

UNLABELLED: At least two quantitative rCBF measurements are needed to evaluate rCBF changes with pharmacological intervention. We have developed the split dose 123I-IMP SPECT method, which enables measurement of rCBF to be repeated in a short time. METHODS: Thirty-one cerebrovascular disease patients were investigated to assess reproducibility and vasoreactivity to acetazolamide. During 44-min dynamic SPECT imaging, 123I-IMP injection and respective arterial sampling were performed twice at an interval of about 25 min. The rCBF values were calculated using a microsphere model in which the washout of 123I-IMP from the brain can be negligible in the first several minutes after injection. For the second rCBF measurement, the remaining activity due to the first 123I-IMP injection was estimated and subtracted from the total brain activity. RESULTS: In ten patients, two consecutive resting mean rCBF values in the MCA territory (CBF1 and CBF2) had good correlation (CBF1 = 47.4 +/- 4.0 (ml/min/100 ml: mean +/- s.d.), CBF2 = 45.2 +/- 8.2, CBF2 = 0.900*CBF1 + 2.9, r = 0.915). In 11 patients with occlusive lesions in the unilateral ICA system, mean rCBF in the MCA territory was increased by only 27.7% +/- 14.0% in the affected side by a 1-g intravenous acetazolamide injection, while 44.5% +/- 12.3% increase was found in the nonaffected side. In 10 patients without a major arterial lesion, a 49.7% +/- 17.0% increase of rCBF was demonstrated. CONCLUSIONS: This split dose method 123I-IMP SPECT can be useful to estimate vascular reserve.

Acetazolamide↗
PubMed1994

Carbon dioxide reactivity by consecutive technetium-99m-HMPAO SPECT in patients with a chronically obstructed major cerebral artery.

UNLABELLED: In the management of major cerebral artery obstruction, cerebral perfusion reserve is key to introducing cerebral revascularization surgery. The purpose of this study was to evaluate the feasibility of assessing cerebral perfusion reserve by consecutive 99mTc-hexamethyl-propyleneamine oxime (99mTc-HMPAO) SPECT with 5% carbon dioxide (CO2) inhalation. METHODS: The CO2 inhalation and consecutive 99mTc-HMPAO SPECT study was performed on 30 chronic ischemic cerebrovascular disease patients with unilateral major cerebral artery obstruction and on 27 patients without. CO2 reactivity was expressed as the percent increase of 99mTc-HMPAO accumulation from the baseline (%Change) and as a constant k' that was the ratio of 99mTc-HMPAO accumulation per 1 mmHg change of end-tidal CO2 tension by exponential curve fitting. RESULTS: The mean %Change and k' in the middle cerebral artery (MCA) territory on the side without an obstructive lesion or in the cerebellum ranged from 10.0% to 11.1% and from 0.98% to 1.13% per mmHg, respectively. In the MCA territory, an obstructive lesion was noted in 5.9% versus 0.54% per mmHg in the contralateral MCA territory (p < 0.01). Eleven of 30 patients with major cerebral artery obstruction revealed significant asymmetry in the k' value between bilateral MCA territories. CONCLUSION: The results showed compromised cerebral perfusion reserve in the obstructed major cerebral artery territory. The present method was proven clinically useful for evaluating cerebral perfusion reserve in patients with unilateral major cerebral artery obstruction.

Adult↗
PubMed1993

Induced resistance and susceptibility to cerebral ischemia in gerbil hippocampal neurons by prolonged but mild hypoperfusion.

Brief periods of non-lethal cerebral ischemia can induce resistance against subsequent lethal ischemia. In this study, asymptomatic gerbils after unilateral carotid artery ligation were subjected to 5 min of forebrain ischemia. The prolonged but mild hypoperfusion, by carotid occlusion, induced susceptibility at 1 day and tolerance at 30 days to lethal ischemia in the hippocampal neurons. The neuroprotective effect correlated well with induction of heat shock protein 72 in the hippocampal neurons. These results suggested that neuronal cells possess a cellular response to sublethal hypoperfusion and can survive forthcoming ischemic stress.

Animals↗
PubMed1993

Motility function of the esophagus before primary anastomosis in esophageal atresia.

Two patients with a long gap esophageal atresia without tracheoesophageal fistula underwent an esophageal manometric study before primary anastomosis and one of them underwent an identical study after operation. Before operation both patients showed peristaltic contraction in the proximal esophagus when swallowing which was always followed by a coordinated contraction of the distal esophagus the same as in that of the normal esophagus. These peristaltic contractions induced a reflex relaxation of the lower esophageal sphincter (LES). After operation the manometric studies of the repaired esophagus demonstrated an abnormal esophageal motility, with simultaneous contractions occurring when swallowing in the proximal to the distal esophagus. In addition, the reflex relaxation of LES was incomplete. These data suggest that even if the intraluminal continuity is defective, the esophageal motility function is not disturbed in the proximal to distal esophagus in preoperative esophageal atresia, and that intraoperative mobilization and denervation may be suggested to be an important factor in esophageal dysmotility even when esophageal atresia is successfully repaired.

Anastomosis, Surgical↗
PubMed1993

Differential vulnerability in the hindbrain neurons and local cerebral blood flow during bilateral vertebral occlusion in gerbils.

Differential vulnerability in the hindbrain neurons was examined immunohistochemically during hindbrain ischemia in the gerbil. Hindbrain ischemia was produced by extracranial occlusion of the bilateral vertebral arteries just before their entry into the transverse foramen of the cervical vertebra. Local cerebral blood flow was measured by quantitative autoradiographic technique after 5 min of ischemia and was reduced to less than 5 ml/100 g per min in the cerebellum, the pons, and the medulla, indicating that severe and reproducible hindbrain ischemia was induced immediately after occlusion. For immunohistochemical investigation, four gerbils each were used for each ischemic period of 5, 10, 15, and 30 min. Immunohistochemical lesions, detected by the reaction for microtubule-associated protein 2, were visible in the lateral vestibular nucleus and the cerebellar interpositus nucleus even after 5 min of ischemia. These results suggested that these areas were more vulnerable than others, although blood flow was markedly reduced in various regions of the hindbrain. In contrast, areas related to respiratory or cardiovascular control were rather resistant to ischemia. The present study suggests that selective vulnerability during hindbrain ischemia depends mainly on different metabolic characteristics inherent to various neurons in the hindbrain.

Animals↗
PubMed1993

Late cyclosporine treatment ameliorates established coronary graft disease in rat allografts.

The development of post-transplantation coronary graft disease (CGD) is a major cause of late morbidity and mortality. Recent reports have suggested that CGD is a type of chronic vascular rejection, possibly enhanced by cofactors such as concurrent CMV infection and hyperlipidemia. It remains controversial whether established CGD can be improved by modifications in immunosuppressive therapy. The purpose of this study was to examine whether CsA could reverse or halt the progression of CGD after it was already established. Lewis to Fisher (F-344) heterotopic heart allografts develop CGD resembling human disease. Group 1 (n = 29) had no CsA therapy for chronic rat CMV (RCMV) infection in recipients for 8 weeks before transplant. Group 2 (n = 17) had chronic RCMV infection along with CsA therapy from days 15 to 28 post-transplant. Allografts were killed at 2 and 4 weeks and 90 days post-transplantation. In group 1, leukocyte adhesion to arterial endothelium and intimal hyperplasia were well established at 2 weeks and progressed to stenotic, proliferative arterial lesions at 4 weeks. In group 2, CsA therapy was effective in significantly reversing histologic parameters of vascular rejection such as leukocyte adhesion, intimal proliferation, and periarterial edema at 4 weeks. By 90 days, however, arterial pathology was as severe as in group 1. In conclusion, these results support the hypothesis that CGD is a form of chronic vascular rejection, and once established, can be significantly modified by CsA therapy. These effects are not permanent, and progressive CGD recurs after CsA therapy is discontinued.

Animals↗
PubMed1993

Reactivity of cerebral blood flow to carbon dioxide in various types of ischemic cerebrovascular disease: evaluation by the transcranial Doppler method.

BACKGROUND AND PURPOSE: The response of cerebral blood flow to changes in the arterial carbon dioxide partial pressure (i.e., carbon dioxide reactivity) has been evaluated as a parameter of cerebral perfusion reserve in patients with cerebrovascular disease. In this study, variations in this reactivity in various ischemic cerebrovascular diseases were evaluated by a newly established method, a transcranial Doppler technique. METHODS: Thirty-three patients with symptomatic cerebrovascular disease, 13 patients with asymptomatic cerebral infarction, and 25 age-matched normal control subjects were investigated. The symptomatic patients were divided into three groups; those with unilateral carotid artery obstruction, those with cortical infarction, and those with lacunar infarction. The carbon dioxide reactivity of each subject was determined by simultaneously measuring the mean spatial Doppler frequency in the middle cerebral artery and the end-tidal carbon dioxide partial pressure under normocapnic, hypercapnic, and hypocapnic conditions. RESULTS: In the patients with carotid obstruction, the carbon dioxide reactivity of the hemisphere ipsilateral to the obstruction was more impaired than the reactivity of the symptomatic hemispheres in any other group, and was significantly less than in the contralateral asymptomatic hemisphere (p < 0.01). In patients with cortical infarction, the carbon dioxide reactivity of the symptomatic hemisphere was significantly less than in normal control subjects (p < 0.05) and was also less than that of the contralateral asymptomatic hemisphere (p < 0.05). In patients with lacunar infarction, the carbon dioxide reactivity of both hemispheres was significantly less than that in normal controls (p < 0.01), although there was no difference between the symptomatic and asymptomatic hemispheres. In patients with asymptomatic infarction, the carbon dioxide reactivity was also less than that in normal controls (p < 0.01). CONCLUSIONS: The carbon dioxide reactivity of cerebral blood flow measured by this transcranial Doppler technique may be useful for characterizing the hemodynamic changes that occur in various types of ischemic cerebrovascular disease.

Brain Ischemia↗
PubMed1993

Rate of successful recording of blood flow signals in the middle cerebral artery using transcranial Doppler sonography.

BACKGROUND AND PURPOSE: To assess the usefulness of transcranial Doppler sonography, we investigated the rate of blood flow signal recording failure in the middle cerebral artery in Japanese subjects. Furthermore, we studied the effect of increased emitted power on the rate of successful recording in some of the patients in whom recording failure had been detected at the standard transducer power of 100 mW/cm2. METHODS: To evaluate the rate of successful recording, we measured blood flow signals in 597 patients (age range, 16 to 89 years) for screening of cerebrovascular disease by using a 2-MHz range-gated, pulsed-wave Doppler instrument at the standard transducer power. In 18 elderly patients with recording failure at the standard power, we assessed the effect of increased emitted power of 400 mW/cm2 on flow signal recording. RESULTS: Blood flow signals were recorded in 920 (77.1%) of the 1194 middle cerebral arteries of the 597 patients studied. The rate of successful recording of bilateral middle cerebral artery flow signals (70.9%; 423 of 597 patients) decreased with age, especially in females (17.0% in women aged 70 years or older). In 12 of 18 elderly patients with recording failure at the standard power, blood flow signals could be detected at the increased emitted power of 400 mW/cm2. CONCLUSIONS: The rate of successful recording of blood flow signals in Japanese subjects decreases with advancing age, especially in females. Increasing the emitted power markedly improves the successful recording rate.

Adolescent↗
PubMed1993

Non-invasive assessment of acute effects of cigarette smoking on cerebral circulation.

The usefulness of sequential single photon emission computed tomograph technique using Tc-99m hexamethylpropyleneamine oxime was tested to assess the acute effects on cerebral circulation of cigarette smoking and other activation task. The evaluation of reproducibility, photo-stimulation study, and carbon dioxide inhalation study were carried out. In the subjects, who were examined for cerebral perfusion under the resting condition repeatedly, no significant perfusion changes were detected in visual analysis, in quantitative analysis, or in distribution change mapping. The significant increase of CBF in the occipital lobes was found by photo-stimulation. The CO2 reactivity, estimated by a pair of perfusion images obtained under normocapnia and hypercapnia, was lower in the affected side than in the non-affected side of the patients with unilateral major occlusive lesions in the carotid system. These results showed our method was applicable to assess acute effects on regional CBF of cigarette smoking. Five normal volunteers were investigated for the CBF response to cigarette smoking. Although localized CBF increases were detected in two cases, no characteristic pattern could be found. These results suggested that in normal subjects, the effects of cigarette smoking on regional cerebral circulation varied among individuals, depending on the pharmacological properties of the absorbed nicotine including different sensitivity of each subject to nicotine.

Aged↗
PubMed1993

[Quantitative assessment of cerebral blood flow by 123I-IMP SPECT: venous sampling method with hand warming in the water bath].

In order to establish a noninvasive, quantitative method for measuring regional cerebral blood flow (rCBF) by N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) SPECT, we attempted to employ continuous venous sampling instead of arterial sampling. Forty two patients with cerebrovascular diseases were classified into two groups, with (group II: n = 35) and without (group I: n = 7) hand warming. In group II, either hand was warmed, wrapping in a hot blanket (group IIA) or immersed in a 44 degrees C water bath (group IIB). In each patient, immediately after intravenous bolus injection of 222 MBq IMP, arterial and venous blood samples were collected continuously for 5 min from the radial artery and the cubital vein, respectively. By octanol extraction, IMP was divided into the unmetabolized and metabolized fraction. The ratio of 123I-IMP radioactivity of venous blood compared to arterial blood (pass ratio, referred as %PR) was calculated in three fractions, whole blood, unmetabolized, and metabolized fraction. By using these parameters, we assessed the possibility to estimate the amount of unmetabolized IMP fraction of arterial blood, usually used as an input function, from venous samples. In group I, %PR demonstrated a considerable variation between individuals (whole IMP, 47.5 +/- 24.6% (mean +/- SD): unmetabolized IMP, 46.0 +/- 24.5%: metabolized IMP, 51.8 +/- 27.4%). In group II, especially in group IIB, both increase of %PR value and the decrease in variation (whole, 77.9 +/- 5.6%: unmetabolized, 75.7 +/- 5.7%: metabolized, 86.7 +/- 8.7%) were observed, which permitted the further calculation based on the assumption that %PR value was constant in each IMP fraction (whole blood and unmetabolized fraction).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Spontaneous formation of helical structures from phospholipid-nucleoside conjugates.

Phospholipid-nucleoside conjugates containing two myristoyl groups and a nucleotidyl group, collectively designated as dimyristoyl-5'-phosphatidylnucleosides, were enzymatically synthesized and their self-organization, morphology, and physicochemical properties investigated. The dimyristoyl-5'-phosphatidylnucleosides spontaneously assembled to form various types of helical strands. Neutral and alkaline solutions of dimyristoyl-5'-phosphatidyladenosine (DMPA) produced multihelical strands. The multihelical strand consisted of several single helical strands of approximately 50 A in diameter and helical pitch approximately 100 A. DMPA produced cigar-like scrolls (tubular structures) in acidic solution, which consisted of many double-helical strands aligned parallel to each other. Diacyl-5'-phosphatidyladenosine with a shorter chain length as long as an alkyl group, dilauroyl-5'-phosphatidyladenosine (DLPA), didecanoyl-5'-phosphatidyladenosine (DDPA), and dioctanoyl-5'-phosphatidyladenosine (DOPA) formed extended tape structures having double-helical strands aligned parallel. Dimyristoyl-5'-phosphatidylcytidine (DMPC) produced network structures at an early stage, which were slowly transformed into multihelical strands. The multihelical strands contained some single-helical strands of approximately 55 A in diameter and helical pitch approximately 150 A. DMPA produced no definite helical structure in acidic solution but rather large lamellar structures. Dimyristoyl-5'-phosphatidyluridine (DMPU) produced crystalline platelet structures of approximately 1000 A in width in both alkaline and acidic solution. A 1:1 mixture of DMPA and DMPU formed a new hybrid helical strand having a wide and thick ribbon structure of approximately 300 A in diameter and helical pitch approximately 2000 A. The formation of different helical strands and effects of chain lengths of alkyl groups and a nucleotidyl group in phospholipid-nucleoside conjugates on that of helical strands in aqueous solution are discussed.

Aniline Compounds↗