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Biomedical subjects

Y Tsuda

Publications and source records attributed to Y Tsuda.

At least 217 records · Page 12Linked to original sources
PubMed1988

A controlled study on the effect of pentoxifylline and an ergot alkaloid derivative on regional cerebral blood flow in patients with chronic cerebrovascular disease.

Regional cerebral blood flow (rCBF) in 90 patients with CBF decreased due to vascular diseases was studied by using the xenon 133 inhalation technique and a 32-detector setup. Whereas 30 patients received their standard basic therapy only and were regarded as controls, 30 others received 3 x 2 mg/day of an ergot alkaloid (co-dergocrine mesylate), and 30 others received 3 x 400 mg pentoxifylline (slow-release formulation)/day orally. Therapy was performed for eight weeks and CBF measured before start of treatment, after a four-week treatment period, and at the end of the study. CBF did not change significantly in the control group; both the pentoxifylline and the ergot alkaloid group presented with a significant increase in the CBF. This positive effect was significantly more pronounced in the pentoxifylline group and affected more ischemic than other brain tissues. In addition, symptoms like sleep disturbances, vertigo, and tinnitus improved significantly during the pentoxifylline observation period.

Cerebrovascular Circulation↗
PubMed1988

Discussion and considerations for the excretion mechanism of perfluorochemical emulsion.

It has been assumed that a mononuclear phagocyte system is related to the excretion of PFC emulsions: PFC particles are phagocytized by blood monocytes to be expelled through the lung alveoli. This monocyte-related mechanism may well explain excretion at an early stage when PFC particles are abundant in the blood stream. It does not, however, fully explain the manner by which PFC cells are released from the RES cells into the blood stream and into the adipose tissue. To explain this, the following mechanism has been proposed and discussed based on some experimental results. PFC emulsion particles taken up by the RES organs, are stripped at their surfactant layers in the cells and move across the cell membranes to the blood vessels and into other tissues such as adipose, at a rate that depends on the lipophilicity of the PFC's. In the blood stream, PFCs are delivered by lipoproteins to the lung and excreted into the expired air. Pharmacokinetical analysis with a compartmental model for the excretion also supported this proposed mechanism.

Adipose Tissue↗
PubMed1988

Oxygenation effect of fluosol-DA on hypoxic tumor tissue and retention of PFCs in the tumor-bearing rats.

An i.v. injection of Fluosol-DA 20% without hydroxy-ethylstarch in combination with carbogen (95% Oz and 5% COz) elevated dose-dependently the tumor POz in AH-109A tumor-bearing rats. The elevation of the tumor PO2 by the treatment of Fluosol-DA injection and carbogen breathing was significantly high at the period when the elevated tumor blood flow declined to the original level and lasted for 3 hours following Fluosol injection. Saline injection with carbogen induced a small increase in the tumor PO2. These results suggest that the oxygenation effect of Fluosol was primarily attributed to the oxygen carrying effect of Fluosol itself. The tumor PO2 increased almost linearly with the arterial PO2. The enhancement in tumor growth delay was observed on the 1 hour post 60CO -ray irradiation with carbogen following Fluosol injection in the Lewis lung tumor-bearing BDF; mice, but not with the 1 day-post irradiation. No significant differences were observed in perfluorochemical retention from the blood circulation and in organ distribution between the tumor bearing rats and normal rats.

Animals↗
PubMed1987

Synthetic omega-conotoxin: a potent calcium channel blocking neurotoxin.

The Ca2+ channel blocking action of synthetic omega-conotoxin (omega CTX) was studied on isolated frog dorsal root ganglion neurons using a 'concentration clamp' technique which enabled internal perfusion and rapid external solution change. At 100 nM, omega CTX showed a time-dependent depression of Ca2+ current (ICa). At higher concentrations, omega CTX exhibited a dose-dependent depression of ICa amplitude without changing the current-voltage relationship. Increases in external Ca2+ concentration partly overcame the inhibitory action of omega CTX on the ICa amplitude. At 10 microM omega CTX totally blocked ICa without effect on the Na+ current. It was likely that omega CTX had high selectivity for the Ca2+ channel.

Animals↗
PubMed1987

Effect of hypervolaemic haemodilution of regional cerebral blood flow in patients with acute ischaemic stroke: a controlled study with hydroxyethylstarch.

A controlled study of the effect of hypervolaemic haemodilution on cerebral blood flow (CBF) was performed using 10% hydroxyethylstarch (HES) in 27 patients with acute cerebral ischaemia. Of the patients, 12 were randomly allocated as controls without HES infusion and 15 received 500 ml HES daily, infused over a period of 5-7 h, for 7 days. CBF was measured on days 1, 2 and 7 by the xenon 133 inhalation method and calculated as initial slope index. In the HES-treated group, CBF increased in both hemispheres (P less than 0.001) from day 1 to day 2 and, in addition, in the infarcted hemispheres from day 2 to day 7 (P less than 0.01). In the control group, the hemispheric flow of the involved side had decreased (P less than 0.001) by day 2 and had not significantly changed by day 7; however, in the contralateral hemisphere flow did not change. In hypaemic regions the increase in flow was larger than in other regions in both groups. Regional flow had increased more in the HES-treated group than in controls at both day 2 (P less than 0.01) and day 7 (P less than 0.002). Hypervolaemic haemodilution with HES was able to improve hemispheric and regional flow significantly, particularly in infarcted hemispheres and hypaemic regions with acute cerebral ischaemia.

Aged↗
PubMed1987

Measurements of regional cerebral blood flow in patients following superficial temporal artery-middle cerebral artery anastomosis.

Regional cerebral blood flow (rCBF) was measured using the inhalation xenon 133 technique in 25 patients undergoing superficial temporal artery-middle cerebral artery anastomotic surgery. rCBF was measured once before and 3 times after operation, up to one year. Data were compared to rCBF-measurement in 16 patients with similar diagnosis, age distribution and medical treatment except that they were not operated on. Mean rCBF increased in some patients 4-8 weeks after surgery on the ipsilateral side. Compared to the non-surgical patients mean rCBF at this time was higher over both hemipheres. However, taking a flow increase of at least 15% as being significant only one third of all patients presented with a significant flow increase. Regional flow data indicated that the amount of hypoaemic areas in the operated side decreased significantly. Areas with normal flow increased in number from CBF 1 to the 4-8th week. There were no significant changes in flow distribution over the contralateral side. It was concluded that extracranial-intracranial bypass improves flow in patients with TIA or PRIND respectively only in some cases. Also a return to normal flow distribution can be achieved in only a few cases.

Cerebral Revascularization↗
PubMed1987

Comparison of the effects of infusion with hydroxyethyl starch and low molecular weight dextran on cerebral blood flow and hemorheology in normal baboons.

Cerebral blood flow (CBF) and hemorheological parameters, such as hematocrit, plasma viscosity, and erythrocyte aggregation, were measured before and up to 7 h after 60-min infusions with 10% hydroxyethyl starch (HES), or 0.9% NaCl solution and 10% low molecular weight dextran (LMWD) in a total of 12 normal baboons. Infusion of HES increased CBF up to 48% from the resting level, and decreased hematocrit without an increase in plasma viscosity. Infusion of LMWD decreased hematocrit with an increase in CBF of up to 9.6%, but increased plasma viscosity at the same time. The disaggregating effect for erythrocytes was rather more obvious with LMWD than with HES but without significant difference between them. These data show different rheological effects with infusions of HES and LMWD on the physiological conditions of normal baboons.

Animals↗
PubMed1987

Effect of hypocapnia on cerebral oxygen metabolism and blood flow in ischemic cerebrovascular disorders.

Effects of hypocapnia on cerebral oxygen consumption (CMRO2) and blood flow (CBF) in cerebral ischemia were studied in 19 patients. The CMRO2 did not change significantly during hypocapnia within the whole group of patients, because 10 out of 19 cases showed a decrease (p less than 0.001) and other 9 showed an increase (p less than 0.01) of CMRO2 during hypocapnia. The first 10 showed higher resting CMRO2 (p less than 0.001) and arteriovenous differences of oxygen content (AVDO2; p less than 0.02) than the other 9. However, the resting CBF and CO2 reactivity to hypocapnia were not different between them, and clinical situations were also similar. A dissociation between flow and metabolism was suggested in the first 10 with rather preserved CMRO2, while reduced metabolic demands were suggested in the other 9. Different responses of CMRO2 to hypocapnia are expected in cerebral ischemia, i.e. in cases with rather preserved CMRO2 it decreases despite an AVDO2 increase, suggesting a capability of CMRO2 to respond to CBF reduction, while it increases in cases with more decreased CMRO2, as the AVDO2 increase exceeds the CBF reduction to maintain the decreased CMRO2 for a further CBF reduction. The vascular CO2 reactivity, therefore, might be maintained to be constant between these patients.

Adult↗