PubMed Health⌕ Search

Biomedical subjects

Y Naruo

Publications and source records attributed to Y Naruo.

36 records · Page 2Linked to original sources
PubMed1983

New treatment of cerebral vasospasm with Fluosol-DA 20%: protective effect on cerebral ischemia and change of cerebral blood flow (CBF).

It was found that Fluosol-DA 20% relieves human acute cerebral ischemia resulting from vasospasm in 62% of the cases. However, several problems were encountered during the investigation. The efficacy of the solution was temporary, that is, within 24 hours. This is considered logical because perfluorochemical particles are eliminated fairly rapidly from the circulating blood. Successive administrations should be necessary until cerebral vasospasm is remitted. Another problem is that it is not clear whether the doses of the solution given in this study (10 ml/kg/day) are sufficient or not, since the depth of the cerebral ischemia is considered to vary depending on the case. It might be necessary to change the volume of the solution given in accordance with the depth of the ischemia of each patient.

Blood Substitutes↗
PubMed1982

Efficacy of a blood substitute (Fluosol-DA, 20%) on cerebral ischemia.

Fluosol-DA, 20%, was intravenously infused in 28 patients suffering from cerebrovascular disease, and was found to be effective in 60% of the cases with vasospasm and in 80% of the cases with stenosis and/or occlusion of the artery. Administration of the solution increases r-CBF by 10.1 to 37.9% when measured by either intra-arterial injection or inhalation of 133Xe. However, an increase of arterial oxygen tension appears to have little effect on r-CBF after administration of the solution. The increase of r-CBF caused by Fluosol-DA, 20%, may be due not only to the lowering viscosity of the mixed blood but also to its direct effect on dilating cerebral vessels.

Adult↗
PubMed1982

Biomechanical study on aging changes and vasospasm of human cerebral arteries.

Mechanical properties of human intracranial arteries were studied with regard to their aging changes as well as cerebral vasospasm. There exists a considerable difference in the development of sclerosis between the intracranial and the extracranial arteries. Intracranial arteries are already stiff at birth and become stiffer with age. Their increase in stiffness is attributable to the marked thickening of their walls, which compensates for the decrease of their elastic modulus with age. The pressure-diameter curve of the intracranial vertebral arteries subjected to subarachnoid hemorrhage is biphasic and has a sharp flexion at the pressure of 180 mmHg when their smooth muscle is activated. Pressure elevation yields little change of diameter in the strongly constricted vessel up to the pressure level at the flexion point, above which the constriction is released abruptly. The existence of flexion point at a high pressure level is an important mechanical feature in considering the development of cerebral ischemia produced by the vasospasm.

Adult↗
PubMed1982

[Clinical evaluation of artificial blood substitute (fluosol-DA 20%) in patients of cerebral ischemia].

The efficacy of perfluorochemicals (Fluosol-DA 20%) as an erythrocyte substitute and the changes of regional cerebral blood flow (r-CBF) following the administration of Fluosol-DA were studied. Seventy-three patients suffering from cerebral ischemic diseases were treated by 10 m/kg of Fluosol-DA. Intravenous infusions were performed 126 times. Clinical efficacy could be estimated by neurological signs, r-CBF and EEG findings in 53 patients who were in acute or subacute stage of diseases. These patients were classified into three groups; 1) Vasospasm group consists of 21 patients and 43 times of infusion, 2) Stenosis or occlusion group consists of 21 patients and 29 times of infusion, and 3) Others. Improvement occurred in 65.1% and 65.5% of vasospasm, and occlusion group, respectively. No aggravated case was noted. One out of 126 infusions showed an exanthema. Changes of r-CBF was measured in 20 cases on 32 hemispheres by either inhalation or intra-arterial infection of 133Xenon. r-CBF was increased 25.0% after the administration of Fluosol-DA when measured by intraarterial injection of 133Xenon. The increase of 16.9% in r-CBF was found in 11 cases by the inhalation method. These values were well correlated with that of animal study using monkeys measured by hydrogen clearance method. From the comparison of the effect of Fluosol-DA and Hespander on r-CBF, the mechanism of increased r-CBF by Fluosol-DA 20%, which contains 2.9% of hydroxyethyl-starch, was considered to be not solely due to the lowering of blood viscosities but also due to the dilating effect on cerebral vessels.

Adolescent↗
PubMed1981

Quantitative analysis of microstructural components of human cerebral arteries.

Microstructural components were analyzed quantitatively by means of a microphotometric technique applied to three kinds of major cerebral arteries and two kinds of extracranial arteries of comparable size obtained from human autopsy subjects. No statistically significant difference was found in the fractions of three structural components, elastin (Fe), collagen (Fc), and smooth muscle (Fm), in the total of fractions of these three components and in the ratio between extracranial arteries. The Fe-values were significantly less in cerebral arteries than in extracranial arteries. The Fc/Fe ratios in cerebral arteries were about triple those in extracranial arteries. Although there was no statistically significant difference in the Fe- and the Fm-values between the two age groups, under 49 and over 50 years old, the Fc/Fe ratio were higher in the older age group. This change of microstructural composition with age was more prominent in cerebral arteries than in extracranial arteries.

Adult↗
PubMed1981

Effects of a transfusion with a blood substitute (Fluosol-DA, 20%) on cerebral circulation in the monkey.

Local cerebral blood flow (lCBF) and electroencephalogram were monitored in six monkeys after a transfusion using a perfluorochemical suspension (Fluosol-DA, 20%) that has been manufactured as a blood substitute and is known to be synthetic, biologically inert, and nontoxic and to have a high capacity for carrying oxygen. The animals were mechanically ventilated, and blood gases were maintained at physiological levels. Fluosol-DA, 20% was administered either by an exchange transfusion of 20 ml/kg or by an infusion of 8 ml/kg followed by an exchange transfusion of 12 ml/kg. lCBF was measured using the hydrogen clearance technique. An equation was proposed to estimate the tissue-blood partition coefficient of hydrogen; this coefficient is considered to be dependent upon the amount of perfluorochemicals in the blood and was used to calculate lCBF. Systemic blood pressure, pulse rate, central venous pressure, electroencephalogram, and gas analysis of the blood from the femoral artery, the femoral vein, and the superior sagittal sinus showed little change throughout the experiment. lCBF was increased by 12% (p less than 0.005) after the infusion of Fluosol-DA, 20% of 8 ml/kg and by 31% (p less than 0.02) after the exchange transfusion. Hyperventilation reduced lCBF significantly (p less than 0.005), which implies that the reactivity of the cerebral blood vessels to hypocarbia was not impaired by the administration of FLuosol-DA, 20%. Both the results of this study and the physical properties of Fluosol-DA, 20% suggest that this blood substitute can safely be used for normal human brains and that it might also be effective for ischemic brains.

Animals↗
PubMed1980

Mechanical properties of human cerebral arteries: Part 2. Vasospasm.

Mechanical properties of human intracranial vertebral arteries subjected to subarachnoid hemorrhage were studied. Their pressure-diameter curves are biphasic and have sharp flexion, called flexion points, at a pressure of 181.3 +/- 9.6 mm. Hg when their smooth muscle is activated by KCl 50 mM. The strong vasoconstriction, accompanied by little change in the vascular diameter, is retained up to the pressure level at the flexion point, above which the constriction is released abruptly. The existence of flexion points at a high pressure level is an important mechanical feature in considering the development and treatment of cerebral ischemia produced by vasospasm.

Biomechanical Phenomena↗
PubMed1979

Mechanical properties of human cerebral arteries. Part 1: Effects of age and vascular smooth muscle activation.

Mechanical properties of the smooth muscle component of human arteries were studied under passive and active conditions. There exists a considerable difference in the development of sclorosis in intracranial and extracranial arteries. Intracranial arteries were already stiff at birth and become stiffer with age. Their increase in stiffness is attributable to the marked thickening of their walls, which compensates for the decrease of their elasticity with age. Intracranial arteries constrict more than extracranial arteries, although the maximum active stress developed is essentially the same. This competency of intracranial arteries for vaso-constriction may be related to cerebral vasospasm.

Adolescent↗
PubMed1977

Hypothalamo-pituitary-adrenal function in pituitary adenoma and craniopharyngioma. Part II: insulin test and clinical features.

For the assessment of hypothalamic corticotropin releasing hormone (CRH) secretory function, insulin test, lysinevasopressin test, and rapid ACTH test were performed and plasma crotisol was assayed. Disturbances of CRH secretory activities were found not to be related with the degree of suprasellar extension of tumors, contents of tumors, the degree of visual disturbances, or the duration of symptoms, and it was supposed that more complex mechanisms were responsible for CRH secretory abnormalities.

Adenoma, Chromophobe↗
PubMedDate not supplied

Experimental cerebral vasospasm arterial wall mechanics and connective tissue composition.

The elastic properties of the basilar artery were studied in control and treated dogs in which 3 ml of blood was injected intracisternally. Vascular specimens were resected transclivally as cylindrical segments and their external diameters were measured in vitro in the pressure range from 0 mm Hg to 250 mm Hg in the active condition of smooth muscle in Krebs-Ringer solution and in the passive condition in saline solution. The development of cerebral vasospasm was confirmed comparing the diameter difference between these two conditions. The experimental data indicated that vasospasm was most prominent on the 7th day after the treatment of blood injection. In the passive condition no significant dimensional change (i.e. radius and wall thickness) was observed between the control and the treated arteries at various pressure levels. These results imply that the luminal narrowing under vasospasm is not attributable to an irreversible organic change in the wall but to the constriction of vascular smooth muscle. The treated arteries are more distensible and have lower elastic moduli than the control arteries, possibly due to a change in the content of their connective tissues. These changes of the passive elastic properties of arterial walls after blood injection might be one of the factors affecting the development of cerebral vasospasm.

Animals↗
PubMedDate not supplied

Experimental cerebral vasospasm. Part 2. Contractility of spastic arterial wall.

We studied the mechanical properties of canine basilar arteries subjected to experimental subarachnoid hemorrhage (SAH). Smooth muscle contractility was determined from pressure-diameter curves obtained after subjecting the basilar arteries to three different conditions: Krebs-Ringer solution (KRS), Krebs-Ringer solution containing serotonin (5HT), and saline solution. Pressure-diameter curves obtained in KRS and 5HT are biphasic and have sharp flexions that yield flexion points. The pressure level at the flexion point increases as vasospasm increases. Strong constriction is retained up to that pressure above which the constriction is released abruptly. These data suggest that increasing the intraluminal pressure dilates the spastic artery nonlinearly and that induced hypertension could relieve the cerebral ischemia caused by vasospasm if blood pressure were maintained above the flexion point. The contractile response of spastic arterial wall to serotonin remains unchanged after SAH although the spastic constriction increases progressively and becomes maximal seven days after SAH. The lesser the arterial wall stiffness, the more efficiently it constricts. This means that the diminution of arterial stiffness observed after SAH might be one of the factors promoting the development of vasospasm.

Animals↗
PubMedDate not supplied

Cerebral hemodynamics in arteriovenous malformations: evaluation by single-photon emission CT.

Cerebral hemodynamics in six patients with supratentorial arteriovenous malformations (AVMs) were studied by using single-photon emission CT with three types of radioactive isotopes: N-isopropyl-p-[123I] iodoamphetamine, 81mKr, and 99mTc-RBC in order to determine the local cerebral blood flow and blood volume associated with these malformations. The AVMs were shown to have high flow while other areas of the brain, including the contralateral hemisphere, had variable areas of diminished perfusion. There was increased blood volume in the regions of AVMs, and poor but evenly distributed blood volume in the other regions. CO2 reactivity during hypocapnia was preserved throughout the brain except for the region of the AVMs. In large AVMs, the ischemic state surrounding the nidus was considered to be caused mainly by the cerebral steal phenomenon.

Adult↗