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Biomedical subjects

E Tsuchida

Publications and source records attributed to E Tsuchida.

At least 37 records · Page 2Linked to original sources
PubMed1999

Microvascular responses to hemodilution with Hb vesicles as red blood cell substitutes: influence of O2 affinity.

Phospholipid vesicles encapsulating purified hemoglobin (HbV) were developed to provide O2-carrying capacity to plasma expanders. Microvascular perfusion was determined for HbV with different O2 affinity (P50 = 9, 16, and 30 mmHg) prepared by coencapsulating pyridoxal 5'-phosphate (PLP) at the molar ratios of [PLP]/[Hb] = 0, 0.5, and 3, respectively (cf. hamster blood, P50: 28 mmHg), and suspended in 8 g/dl human serum albumin (HSA). Eighty percent of the red blood cell (RBC) mass of conscious Syrian golden hamsters fitted with dorsal skinfold windows was substituted with either of the HbV-HSA suspensions, washed hamster RBC suspended in HSA (RBC-HSA), and HSA alone. All three HbV-HSA groups and RBC-HSA groups showed stable blood pressure and heart rate, which could not be sustained with HSA alone. Only the HbV (P50 = 9)-HSA group showed an increase in arterial O2 tension (89.8 +/- 14.7 mmHg, baseline 58.4 +/- 4.0 mmHg) because of hyperventilation, and microvascular perfusion was decreased, indicating that facilitated O2 unloading of HbV by decreasing the O2 affinity (increasing P50) with PLP as an allosteric effector is important. Microvascular perfusion and microvascular and interstitial O2 tensions in the HbV (P50 = 16 and 30)-HSA groups were significantly higher than those in the HSA group. The O2 release rate from the HbV was 18-32 s-1 vs. 4.4 s-1 for RBC. Functional capillary density was improved from 17 to 41% on average by decreasing P50 from 30 to 16 mmHg, which appears to be an optimal value for the P50 in this system.

Animals↗
PubMed1999

Changes in resistance vessels during hemorrhagic shock and resuscitation in conscious hamster model.

The unanesthetized hamster dorsal skinfold preparation was used to monitor diameters and blood flow rates in resistance arteries (small arteries, A0: diameter, 156 +/- 23 micrometers) and capacitance vessels (small veins, V0: 365 +/- 64 micrometers), during 45 min of hemorrhagic shock at 40 mmHg mean arterial pressure (MAP) and resuscitation. A0 and V0 vessels constricted significantly to 52 and 70% of the basal values, respectively, whereas precapillary arterioles (A1-A4, 8-60 micrometers) and collecting venules (VC-VL, 26-80 micrometers) did not change or tended to dilate. Blood flow rates in the microvessels declined to <20% of the basal values. Resuscitation with shed autologous blood (SAB) showed incomplete recovery of A0 and V0 diameters even 2 h after resuscitation (71 +/- 14% and 81 +/- 18%, respectively, of basal value), whereas other vessels did not change significantly. The behavior of A0 diameter coincided with the incomplete recovery of blood flow rates in all the vessels (ca. 50%) according to Poiseuille's law, and the incomplete recovery of functional capillary density (ca. 75%). Resuscitation with 8% human serum albumin in saline (HSA) tended to show higher levels of A0 constriction and A4 dilation and lowered blood flow rates. Resuscitation with SAB restored tissue PO2 27 +/- 10 mmHg after 2 h, which was near control levels (28 +/- 5 mmHg), whereas resuscitation with HSA caused tissue PO2 to remain significantly depressed (6 +/- 2 mmHg), and flow rates were significantly lower than resuscitation with SAB. These results indicate that response of the A0 vessels is the crucial determinant of blood flow in the observed area. The constriction of A0 may help sustain MAP, and constriction of V0 may enhance blood redistribution from the skin to the vital organs under the hypotensive condition.

Animals↗
PubMed1998

Distribution of heme oxygenase isoforms in rat liver. Topographic basis for carbon monoxide-mediated microvascular relaxation.

Carbon monoxide (CO) derived from heme oxygenase has recently been shown to play a role in controlling hepatobiliary function, but intrahepatic distribution of the enzyme is unknown. We examined distribution of two kinds of the heme oxygenase isoforms (HO-1 and HO-2) in rat liver immunohistochemically using monoclonal antibodies. The results showed that distribution of the two isoforms had distinct topographic patterns: HO-1, an inducible isoform, was observed only in Kupffer cells, while HO-2, a constitutive form, distributed to parenchymal cells, but not to Kupffer cells. Both isoforms were undetectable in hepatic stellate cells and sinusoidal endothelial cells. Of the two isoforms, HO-2 in the parenchymal cell rather than HO-1 in the Kupffer cell, appears to play a major role in regulation of microvascular tone. In the perfused liver, administration of HbO2, a CO-trapping reagent that can diffuse across the fenestrated endothelium into the space of Disse, elicited a marked sinusoidal constriction, while administration of a liposome-encapsulated Hb that cannot enter the space had no effect on the microvascular tone. These results suggest that CO evolved by HO-2 in the parenchymal cells, and, released to the extrasinusoidal space, served as the physiological relaxant for hepatic sinusoids.

Animals↗
PubMed1998

Subcutaneous microvascular responses to hemodilution with a red cell substitute consisting of polyethyleneglycol-modified vesicles encapsulating hemoglobin.

Phospholipid vesicles encapsulating purified hemoglobin [Hb vesicles (HbV); diameter 259 +/- 82 mm; oxygen affinity 31 mm Hg; [Hb] 5 and 10 g/dL] were developed to provide oxygen-carrying capacity to plasma expanders. Their function as a blood replacement was tested in the subcutaneous microvasculature of awake hamsters during severe hemodilution in which 80% of the red blood cell mass was substituted with suspensions of the vesicles in 5% human serum albumin (HSA) solution. Vesicles were tested with membranes that were unmodified (HbV/HSA) or conjugated with polyethyleneglycol (PEG) on the vesicular surface (PEG-HbV/HSA). The viscosity of 10 g/dL HbV/HSA was 8 cP at 358 s-1 owing to the intervesicular aggregation, while that of 10 g/dL PEG-HbV/HSA was 3.5 cP, since PEG chains inhibit aggregation. Both materials yielded normal mean arterial pressure, heart rate, and blood gas parameters at all levels of exchange, which could not be achieved with HSA alone. Subcutaneous microvascular studies showed that PEG-HbV/HSA significantly improved microhemodynamic conditions (flow rate, functional capillary density, vessel diameter, and oxygen tension) relative to unmodified HbV/HSA. Even though the enhancement of PEG modification did not achieve the functional characteristics of the blood-perfused microcirculation, PEG reduced vesicular aggregation and viscosity, improving microvascular perfusion relative to the unmodified type. These results highlight the significance of microvascular analysis in the design of red cell substitutes and the necessity of surface modification of HbV to prevent aggregation.

Animals↗
PubMed1998

Serum protein exudation in chronic subdural haematomas: a mechanism for haematoma enlargement?

A study was conducted to investigate the role of serum protein exudation in the aetiology of chronic subdural haematoma (SDH). Scintigraphy after intravenous injection of 99mTc-labelled human serum albumin (HSA) was performed in three patients with chronic SDH and a patient with subdural effusion. In another 60 haematomas, the amounts of total protein and albumin as indices of serum exudation were measured, and then compared among low-density, iso-density and high-density haematomas. Accumulation of 99mTc-HSA in the haematoma cavity was seen 6 h after isotope injection and became more evident at 24 h. However, the protein concentrations and albumin ratios in the haematomas exhibited a reciprocal relationship, suggesting that not all the protein in the haematomas was derived from serum exudation. The higher the total protein concentration in the haematoma became, the higher the haematoma density which was observed on CT. The albumin concentration in low-density haematomas was lower than that in iso-density and high-density haematomas, whereas no significant difference was seen between the latter two haematoma types. These results provide morphological evidence for serum protein exudation into the haematoma cavity, and therefore it is possible that serum protein exudation plays a role in the progression of chronic SDH and is related to changes in haematoma density on CT.

Adult↗
PubMed1998

Feasibility of the titration method of mild hypothermia in severely head-injured patients with intracranial hypertension.

OBJECTIVE: Clinical strategy to maximize effectiveness and to minimize adverse influences remains to be determined for mild hypothermia therapy for traumatic brain injury. This study was conducted to evaluate the clinical feasibility of the titration method of mild hypothermia in severely head-injured patients in whom a reduction in intracranial pressure was regarded as the target effect. METHODS: Nine consecutive patients with severe head injury were studied. Patient age ranged between 18 and 66 years, Glasgow Coma Scale scores were equal to or less than 8, and intracranial pressures were equal to or greater than 20 mm Hg despite removal of intracranial hematoma and drugs, including glycerol and thiopental. During a maximum of 6 days of hypothermia therapy, jugular venous blood or cerebrospinal fluid temperature was titrated to reduce intracranial pressure to less than 20 mm Hg by means of repeated intragastric cooling with our nasoduodenal tube and surface cooling. The feasibility and the effects on systemic complications of this titration method of mild hypothermia were evaluated. RESULTS: Intracranial pressure variably decreased from before to 3 hours after the beginning of all procedures of cooling. The mean intracranial pressure significantly decreased from 24 to 15 mm Hg with cooling, while temperature reduced an average of 2.0 degrees C. Four patients had systemic infection complications. Increased C-reactive protein and decreased platelet count were observed in all patients during hypothermia. The incidence of good recovery and moderate disability according to the Glasgow Outcome Scale was seven of nine patients. CONCLUSION: The titration method of mild hypothermia to control intracranial hypertension in severely head-injured patients is clinically feasible. However, the method failed to reduce the incidence of infectious and hematological complications.

Adolescent↗
PubMed1998

Effects of the pH-controlled hemoglobin vesicles by CO2 gas.

The hemoglobin vesicle (HbV) is a red cell substitute encapsulating purified concentrated Hb in a phospholipid vesicle. In order to improve the oxygen carrying capability of HbV, the pH value of the Hb solution should be adjusted to 7.0 in the HbV preparation, and then the pH value should be adjusted to 7.4 where HbV functions as an oxygen carrier, because the maximum value of [Hb]/[Lipid] was obtained in which the pH of the Hb solution was 7.0, and the metHb formation rate was suppressed in the pH 7.4. Generally, the pH control of the inner aqueous phase of HbV is difficult by changing the pH in the outer phase. We could control the pH of the Hb solution from 7.4 to 7.0 by dissolving CO2 into the Hb solution, and after the preparation of HbV, the pH of HbV is changed to 7.4 by reducing the pressure. The resulting pH-controlled HbV by CO2 gas showed a high [Hb]/[Lipid] value of 1.7 with a low rate of metHb formation.

Arylsulfonates↗
PubMed1998

Oxygen releasing from cellular hemoglobin.

The oxygen-releasing behavior of hemoglobin vesicles (HbV) was measured in order to study the difference in oxygen dynamics inside and outside the cellular Hb using a conventional stopped flow method and a newly developed stopped flow flash photolysis method. The partial pressure of oxygen in the solution outside the HbV was monitored with the lifetime of the triplet state of meso-tetraphenylporphinatozinc(II) bound to human serum albumin excited by the laser flash. The change in the partial pressure of oxygen outside the HbV showed a biphasic profile and was slower than that inside the HbV. The first phase shows the oxygen-releasing process from Hb near the phospholipid bilayer membrane, and the second phase is considered the process in which oxygen diffuses to the bulk aqueous region and reaches the equilibrium value.

Blood Substitutes↗
PubMed1998

Human serum albumin-bound synthetic hemes as an oxygen carrier: determination of equilibrium constants for heme binding to host albumin.

Human serum albumin (HSA) incorporating synthetic tetraphenylporphinatoiron(II) derivatives (FeP1 or FeP2) can bind and release oxygen reversibly under physiological conditions (in aqueous media, pH 7.4, 37 degrees C). The maximal binding ratio of FeP1/HSA was estimated to be eight, and the stepwise equilibrium constants for FeP1 binding to HSA (K1-K8) ranged from 1.2 x 10(6) to 1.3 x 10(4) M-1. The major binding sites of FeP1 are presumably identical to those of hemin, bilirubin and long-chain fatty acids. The O2-binding ability of the HSA-FeP can be regulated by changing the molecular structure of the incorporated hemes. The half-lifetime of the O2-coordinated FeP2 in HSA was significantly longer than that of HSA-FeP1.

Binding Sites↗
PubMed1997

The effect of UCN-01 (7-hydroxystaurosporine), a potent inhibitor of protein kinase C, on fractionated radiotherapy or daily chemotherapy of a murine fibrosarcoma.

PURPOSE: To investigate the effect of UCN-01 (7-hydroxystaurosporine), a potent and selective protein kinase C inhibitor, on fractionated irradiation or daily chemotherapy; cis-diamminedichloroplatinum(II) (cis-DDP) or 5-fluorouracil (5-FU) in vivo. Radiosensitivity and chemosensitivity given in combination with UCN-01 were further studied in vitro to analyze these in vivo results. METHODS AND MATERIALS: For in vivo studies, single-cell suspension was prepared from fourth generation FSa-II tumors and transplanted subcutaneously into the leg of 8-10-week-old C3Hf/Sed mice. Treatments were initiated when tumors reached an average diameter of 4 mm. Tumor response was studied using tumor growth and growth delay time assays. UCN-01 was given continuously for 7 days using Alzet osmotic pump (4.0 microg/microl/h or approximately 3.2 mg/kg/day). A daily gamma-ray dose of 10 Gy each was given in air for 7 days. Cis-DDP (0.7 mg/kg/day) or 5-FU (20 mg/kg/day) was given by an i.p. injection for 7 days. For in vitro studies, an established FSa-II cell line was used and cell survival was studied by colony formation assay. RESULTS: UCN-01 acted synergistically with fractionated irradiation, though it was slightly radioprotective in vitro and had no effect on SLD repair. The surviving fraction of the FSa-II cells treated with both UCN-01 and cis-DDP in vitro was lower than the calculated additive effect; however, the sensitizing effect of UCN-01 was not found when combined with either of the chemotherapeutic agents in vivo. Possible causes of synergism of combined UCN-01 and fractionated radiation may be that a continuous UCN-01 treatment inhibited clonogen repopulation during the course of fractionated irradiation and accumulated cells in the G2-M phase where cells are most sensitive to irradiation. CONCLUSION: UCN-01 is a promising agent that may indirectly interact with fractionated irradiation in vivo but may not with chemotherapeutic agents.

Alkaloids↗
PubMed1997

Synergistic cytotoxicity between a protein kinase C inhibitor, UCN-01, and monoclonal antibody to the epidermal growth factor receptor on MDA-468 cells.

Cytotoxic effect of the monoclonal antibody to the epidermal growth factor receptor (anti-EGFR MAb) given alone or in combination with UCN-01, a selective protein kinase C inhibitor, was investigated in vitro. MDA-468 human breast cancer cells expressing both a large amount of EGF receptors and its ligand, transforming growth factor a, were used. A given number of the cells were plated and treated with the MAb and/or UCN-01 for 48 h. These cells were replated and incubated for colony formation assay. Cytotoxicity of the anti-EGFR MAb alone was hardly detected. However, when cells were treated with both anti-EGFR MAb and UCN-01, the combined cytotoxic effect was synergistic.

Alkaloids↗
PubMed1997

Effects of mild hypothermia on nitric oxide synthesis following contusion trauma in the rat.

The exact mechanism of hypothermic cerebroprotection after traumatic brain injury (TBI) is not fully understood. The present study was conducted to investigate the effects of mild hypothermia on trauma-induced synthesis of nitric oxide (NO), which has been implicated in the pathogenesis of ischemic brain damage associated with glutamate neurotoxicity. Cerebral contusion was created in the rat parietal cortex by a weight-drop method, and extracellular concentrations of the NO end products nitrite and nitrate were measured using in vivo brain microdialysis and capillary electrophoresis under normothermic (37 degrees C) and mild hypothermic (32 degrees C) conditions. In normothermic animals, the level of NO end products increased markedly 10 min after contusion, reaching a maximum level at 20 min. In the hypothermic rats, such increases were absent. Although it is unknown whether endothelial NO synthase, neuronal NO synthase, or both caused the elevation of the NO end products seen in the normothermic animals, the present results indicate that inhibition of NO synthesis may play a part in hypothermic cerebroprotection following TBI.

Animals↗
PubMed1997

The neuroprotective effect of the forebrain-selective NMDA antagonist CP101,606 upon focal ischemic brain damage caused by acute subdural hematoma in the rat.

The neuroprotective effects of drugs that act against excitotoxic damage, caused by glutamate, are well described in focal ischemia, but behavioral effects, and apparent failure in clinical trials of "first-generation" competitive N-methyl D-aspartate (NMDA) antagonists, such as Selfotel (CGS19755), has led to interest in evaluating newer NMDA antagonists with fewer behavioral effects. We have therefore evaluated the neuroprotective effect of a new forebrain-selective polyamine site NMDA antagonist, CP101,606 in a rat subdural hematoma (SDH) model. An SDH was produced by slow injection of 0.4 ml autologous blood into the parietal subdural space. Brain damage was assessed histologically at eight coronal planes, in animals sacrificed 4 h after induction of hematoma. The drug was infused 30 min after induction of SDH. The reductions of ischemic brain damage achieved by CP101,606, was 29% for the low dose and 37% for the high dose. This novel glutamate antagonist has shown a magnitude of neuroprotection which is comparable with that seen with "first-generation" NMDA antagonists such as MK801, D-CPP-ene and CGS19755, in this same model. This new agent is claimed to have fewer psychomotor and behavioral effects than MK801, D-CPP-ene, and CGS19755.

Animals↗
PubMed1997

Facilitated oxygen transport with modified and encapsulated hemoglobins across non-flowing solution membrane.

The oxygen-transporting capability of modified and encapsulated hemoglobins and red cells is discussed from a physico-chemical standpoint in order to design oxygen-delivering fluids. The oxygen diffusion coefficient toward oxygen-deficient sites was estimated by measuring the oxygen flux across thin solution membranes of hemoglobin, polymerized hemoglobin, liposome-encapsulated hemoglobin, and red cells. Oxygen flux was enhanced several times over that of nitrogen for the hemoglobin and red cell solution with ca [Hb] = 10 and 15 g/dl, respectively. The enhancement in the oxygen diffusion is ascribed to the facilitated transport of oxygen via the hemoglobins. This was in contrast to the simple and physical oxygen-diffusivity in response to its concentration gradient, in the absence of hemoglobins. The flux of the oxygen transport was in the order of hemoglobin > red cells > polymerized hemoglobin > encapsulated hemoglobin, which was ascribed to the facilitated transport efficiencies of oxygen with hemoglobins in a non-flowing or stationary solution.

Animals↗
PubMed1997

The oxygen carrying capability of hemoglobin vesicles evaluated in rat exchange transfusion models.

To evaluate the oxygen transporting capability of Hemoglobin vesicles (HbV) the physiological responses to 40% and 90% exchange transfusions with HbV in anesthetized rat were observed. Hb concentration of HbV dispersions is 10 g/dL. HbV dispersed in phosphate buffered saline and HbV dispersed in 5% albumin solution were used as samples for 40% and 90% exchange transfusions, respectively. HbV surface-modified with polyoxyethylene (HbV-Poe) was also used in the 90% exchange transfusion. As controls, phosphate buffered saline, 5% albumin solution, and HbV containing methemoglobin and therefore deprived of oxygen transporting capabilities (metHbV) were administered as non-oxygen carrying fluids and washed rat red blood cells (ratRBC) as an oxygen carrying fluid. Measurements included mean arterial pressure, arterial blood gas analyses, aortic blood flow and renal cortical tissue oxygen tension. At the completion of the exchange transfusion renal cortical tissue oxygen tensions along with oxygen delivery and consumption were sustained almost equally well with the HbV dispersion compared to the washed rat red blood cell dispersion, but declined significantly in the phosphate buffered saline and albumin solutions. These results indicated that the oxygen transporting capability of HbV was almost equivalent to that of rat red blood cells. In the HbV-Poe group, aortic blood flow was sustained higher in comparison to the HbV group. As for the blood gas parameters, pH and venous oxygen tensions in the HbV-Poe group tended to be higher than those in the HbV group.

Animals↗
PubMed1996

Physiologic responses to exchange transfusion with hemoglobin vesicles as an artificial oxygen carrier in anesthetized rats: changes in mean arterial pressure and renal cortical tissue oxygen tension.

OBJECTIVES: To evaluate the oxygen transporting capabilities of hemoglobin vesicles by studying the physiologic responses to exchange transfusion with hemoglobin vesicles in anesthetized rats. Exchange transfusions with phosphate buffered saline, hemoglobin vesicles containing methemoglobin (and therefore, deprived of oxygen transporting capabilities), and washed rat red blood cells were used as controls. DESIGN: Prospective, randomized, controlled trial. SETTING: Department of Surgery, School of Medicine, Keio University. SUBJECTS: Twenty-seven male Wistar rats. INTERVENTIONS: The rats were anesthetized with an intraperitoneal injection of sodium pentobarbital (50 mg/kg). Catheters (PE-20 tubing, outer diameter 0.8 mm, inner diameter 0.5 mm) were introduced into the right jugular vein for infusion and the right common carotid artery for blood withdrawal and mean arterial pressure measurements. The left kidney was exposed by median abdominal incision, and a needle-type polarographic oxygen electrode was placed in the left renal cortex for renal cortical tissue oxygen tension measurements. MEASUREMENTS AND MAIN RESULTS: Phosphate buffered saline and methemoglobin vesicles were administered as nonoxygen-carrying fluids, and rat red blood cells as oxygen-carrying fluid. Measurements included mean arterial pressure, arterial blood gas analysis, and renal cortical tissue oxygen tension as an indicator of systemic oxygen transport. In the rat red blood cell and hemoglobin vesicles groups, mean arterial pressure was sustained at the end of the exchange transfusion (82.3 +/- 27.5% and 73.5 +/- 11.5%, respectively, from the basal values). However, in the phosphate buffered saline and methemoglobin vesicles groups, mean arterial pressure decreased significantly (p < .05) (33.9 +/- 13.8% and 35.7 +/- 8.2%, respectively). Renal cortical tissue oxygen tension in the rat red blood cell and hemoglobin vesicles groups was sustained at a significantly higher level (p < .05) (83.5 +/- 9.3% and 75.0 +/- 11.9%, respectively) compared with the phosphate buffered saline and methemoglobin vesicles groups (44.9 +/- 12.8% and 58.3 +/- 6.2%, respectively) at the end of the exchange transfusion. Metabolic acidosis was more progressive in the phosphate buffered saline and methemoglobin vesicles groups, manifested as lower pH and base excess values. Platelet counts tended to decrease slightly in the hemoglobin vesicles and methemoglobin vesicles groups, but the changes were not significant. CONCLUSIONS: Hemoglobin vesicles have an oxygen transporting capability almost equivalent to rat red blood cells and can be considered as a potential artificial oxygen carrier.

Anesthesia↗