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Biomedical subjects

K Sakurai

Publications and source records attributed to K Sakurai.

At least 163 records · Page 9Linked to original sources
PubMed1995

[A survey of virtual reality research: From technology to psychology].

A technology of virtual reality enables us to immerse ourselves into 3D synthesized environments. In this paper, I review recent researches on virtual reality focusing on (a) the terminology used in this research area, (b) technological approaches to setting up different components of virtual reality autonomy, interaction, and presence, (c) objective measures and subjective ratings of a viewer's sense of presence in virtual environments, (d) present applications of virtual reality in different fields and their relation to pictorial communication. This review concludes that intermodality conflict and measurement of sense of presence are the crucial perceptual and cognitive topics in virtual reality research.

Computer Simulation↗
PubMed1995

Suppression of pannus-like extension of synovial cells by lipid-derivatized chondroitin sulphate: in vitro and in vivo studies using Escherichia coli-induced arthritic rabbits.

In rheumatoid arthritis, pannus formation resulting from synovial inflammation is a major factor in cartilage destruction. The ability of arthritic synovial cells to undergo pannus formation depends upon their initial adhesion to the partially deformed cartilage surfaces. Our recent studies using various lipid-derivatized glycosaminoglycans have revealed a preeminent inhibitory activity of phosphatidyl ethanol amine-derivatized chondroitin sulphate (CS-PE) toward cell-matrix adhesion. Here we evaluate whether CS-PE may protect articular cartilage from pannus extension in different in vitro and in vivo model systems using Escherichia coli 0:14-induced arthritis in rabbits and the articular cartilage explants, synovial tissues, and synovial cells obtained from them. These studies showed that CS-PE suppressed the in vivo pannus-like extension on cartilage surfaces, as well as the in vitro extension of the synovial cell layer on both CS-PE treated culture plates and cartilage explants. The results suggest that native chondroitin sulphate proteoglycans in the surface of normal articular cartilage play an important role in protecting the tissues from pannus extension and that the CS-PE immobilized onto partially eroded cartilage can mimic the inhibitory action of native chondroitin sulphate proteoglycans.

Animals↗
PubMed1995

[Clinicopathological studies of anti-HCV P1P4 core antibody].

Anti-P1P4 core antibody, derived from a Japanese hepatitis C virus clone, was evaluated clinicopathologically in serum samples from 40 blood donors positive for anti-HCV antibody by 2nd generation assay and in 37 patients with HCV chronic hepatitis treated with interferon. The presence of anti-P1P4 antibody was highly correlated with the presence of HCV-RNA in the blood donors. In the patients with chronic hepatitis, more than a 50% reduction in P1P4 antibody titer after interferon therapy suggested the disappearance of HCV-RNA from the blood. Thus, anti-P1P4 antibody was useful in evaluating the virological effects of interferon therapy. However, clinically and pathologically, the titer of P1P4 antibody did not indicate the grade of liver inflammation.

Hepacivirus↗
PubMed1995

Inhibitory effects of newly synthesized Ser-contained GABA-peptides administered into either caudate putamen or amygdala on methamphetamine-induced hyperactivity.

The locomotor activities induced by methamphetamine (MAP: 1 mg/kg) following the microinjection of either GABA or three synthesized GABA-peptides (PLG, PSLG, PDSLG) into the rat caudate putamen or the amygdala were measured by using behavioral analysis. The ip administration of MAP induced hyperactivities in a time-dependent manner, and the maximum activity was measured 30 min after MAP administration. This hyperactivity was observed for more than 2 hrs. By the microinjection of GABA-peptides (0.054-540 nmol) into each brain region, the MAP-induced hyperactivity was significantly reduced in a dose-dependent manner, although the single administration of examined dosages of these peptides did not influence the locomotor activity. In the case of microinjection of GABA into either one of the brain regions, only the larger dosage (27,000 nmol) significantly reduced the MAP-induced hyperactivity, whereas this inhibition was less than that seen at the dose of 540 nmol of GABA-peptides. Furthermore, the microinjection of newly synthesized GABA-peptides, PSLG and PDSLG, into the caudate putamen was more effective than those obtained by injection into the amygdala. However, either microinjection of PLG or GABA into both regions showed similar inhibition. These results suggest that the pharmacological properties of newly synthesized GABA-peptides are different compared to those of PLG and GABA, and that these differences might be due to the primary inhibitory effects of the serine-contained GABA-peptides on dopaminergic neuronal activity, but not on GABA neurons.

Amygdala↗
PubMed1995

[Inhibitory effects of Forskolin on hepatic metastasis from human colon cancer in nude mice].

Platelet aggregation has been believed to play an important role in implantation of tumor cells into the target organ during the early phase of tumor metastasis. In the present study, the effects of Forskolin, a strong platelet aggregation inhibitor, on experimental hepatic metastasis from human colon cancer (HT29LMM) in nude mice and inhibitory effects of Forskolin on platelet aggregation in the presence of tumor cells were evaluated. A hepatic metastasis model was established by intrasplenic implantation of 3-4 x 10(6) of HT29LMM human colon cancer cells in nude mice. Intraperitoneally 10mg/kg of Forskolin was given 30 minutes before and 24 hours, after implantation of tumor cells, respectively. The control group received saline instead of Forskolin. Phase of hepatic metastasis has been compared for the total weight of hepatic metastatic lesions and the occupied rate between the Forskolin-given group and the control group. The total weight of hepatic metastasis lesions (0.36 +/- 0.33g (SD) vs 3.36 +/- 1.31g) and the occupied rate (8.22 +/- 7.91% vs 67.9 +/- 23.2%) were significantly low in the Forskolin-given group compared with the control group. In vitro inhibitory effects of Forskolin on platelet aggregation was recognized under the presence of HT291LMM. This study suggests that the platelet aggregation inhibitor drug. Forskolin, inhibits hepatic metastasis from human colon cancer by preventing platelet aggregation during the metastatic tumor formation.

Animals↗
PubMed1995

Protection by baicalein against ascorbic acid-induced lipid peroxidation of rat liver microsomes.

The effect of baicalein (5,6,7-trihydroxy-2-phenyl-4H-1-benzopyran-4-one), a flavonoid isolated from Scutellaria baicalensis Georgi, on lipid peroxidation in rat liver microsomes was studied. Ascorbic acid-induced lipid peroxidation in microsomes obtained from baicalein-treated rats was inhibited by treatment on different days and at different doses. Iron release induced by ascorbic acid from microsomes of baicalein-treated rats was markedly lower than from microsomes of control rats. However, no statistical differences in total, nonheme and nonprotein-bound (free iron) iron contents could be detected in the two microsomes. The degradation of calf thymus DNA, an indicator of free iron existence, was observed in the reactions of microsomes obtained from control and baicalein-treated rats with ascorbic acid in the presence of bleomycin. These results suggest that baicalein can inhibit lipid peroxidation in microsomes induced by ascorbic acid by forming an inert complex of iron.

Animals↗
PubMed1995

UNIX based client/server hospital information system.

SMILE (St. Luke's Medical Center Information Linkage Environment) is a HIS which is a client/server system using a UNIX workstation under an open network, LAN(FDDI&10BASE-T). It provides a multivendor environment, high performance with low cost and a user-friendly GUI. However, the client/server architecture with a UNIX workstation does not have the same OLTP environment (ex. TP monor) as the mainframe. So, our system problems and the steps used to solve them were reviewed. Several points that are necessary for a client/server system with a UNIX workstation in the future are presented.

Computer Communication Networks↗
PubMed1995

Dental treatment considerations for the pre- and post-organ transplant patient.

Organ transplantation is a viable treatment for individuals whose quality of life is significantly impaired. There has been a dramatic increase in the number of whole organ transplants being performed over the past few years; and although somewhat limited by donor availability, these numbers have continued to increase as success rates improve and more medical centers perform them. The number of solid organ transplants performed throughout the world has grown from 35,628 (1980-1990) to 285,561 (1989-1991). The number of patients on the waiting list for organs has increased by 59.4 percent from 1988 to 1993. As this patient population grows, the community-based dental practitioner will be faced with a special set of concerns. Understanding the diverse precautions for treatment of pre- and post-organ transplant patients will help the practitioner adequately treat the dental needs of this patients population.

Dental Care for Chronically Ill↗
PubMed1994

[Influence of bone marrow fat on the determination of bone mineral content by QCT].

Single-energy quantitative CT (SEQCT) is thought to be suitable for long-term observation of changes in bone mineral content in individual patients. However, in patients with osteoporosis, an increase in bone marrow fat cannot be ignored. The relationship between bone marrow fat and bone mineral density (BMD) at different tube voltages of 80 kV and 120 kV was investigated using a set of solution phantoms that we devised, and was also studied in healthy volunteers. On the basis of the results obtained using the solution phantoms, the influence of bone marrow fat accounted for a decrease of 8.9 mg/cm3 in BMD value at 80 kV and of 10.8 mg/cm3 at 120 kV in the presence of 10 vol% fat. These findings suggested that the influence of fat was less at a lower tube voltage. The formulas used to estimate the true bone mineral and fat contents from the BMD values at low and high tube voltages were derived by eliminating the influence of beam hardening. Using these formulas, we studied healthy volunteers, and found that the difference between the true BMD value and the BMD value calibrated for beam hardening averaged 17.8 mg/cm3 at 80 kV and 22.6 mg/cm3 at 120 kV. Moreover, the estimated concentration of bone marrow fat in the volunteers averaged 25.0 vol%. In conclusion, because SEQCT performed at a low tube voltage is less influenced by bone marrow fat, it should be selected for assessment of the clinical response to therapy and for studying sequential changes. However, in patients with a low bone mineral content indicated by SEQCT, it would be worthwhile trying to estimate both true mineral and fat contents in bone using the formulas obtained in this study in order to differentiate decrease in bone mineral from interference by bone marrow fat.

Adult↗
PubMed1994

Effects of intralesional injection of cisplatin dissolved in urografin and lipiodol on Ehrlich ascites tumor and normal tissues of CD-1 mice.

The response of Ehrlich ascites tumor and the effect on normal tissues (kidney and small intestine) of CD-1 mice were evaluated after intralesional (i.l.) injection of cisplatin dissolved in urografin and lipiodol, which is henceforth termed CUL suspension. The results obtained were compared with the effects of i.p. and i.l. injections of cisplatin dissolved in sterile distilled water. Each of these treatment modalities involves the injection of 10 mg/kg cisplatin. The tumor response was evaluated by tumor growth-delay studies as well as by determining the percentage of cells in the S phase. Toxicity studies were accomplished by evaluation of the change in the body weight of mice and also by S-phase studies. S-phase fraction analyses were done with the use of the Cell Proliferation Kit. This commercial kit was used to measure bromodeoxyuridine (BrdU), a thymidine analogue that is incorporated into cells synthesizing DNA. Tumor, kidney, and small-intestine platinum concentrations were determined by measurement with a flameless atomic absorption spectrophotometer. The results of the tumor growth-delay studies showed that i.p. injection, with water being the drug carrier, produced the weakest antitumor effect, whereas i.l. injection of cisplatin, with lipiodol being the drug carrier, evoked the most enhanced effect. This finding was substantiated by BrdU-uptake analysis of tumor cells, wherein i.p. injections yielded the highest S-phase fraction and CUL treatment gave the lowest. Toxicity studies showed that a very significant decrease in body weight occurred in mice receiving i.p. treatment. No significant decrease in body weight was noted after i.l. treatment. BrdU analysis revealed that DNA synthesis in kidney cells and crypt cells of the small intestine was depressed after i.p. treatment. On the other hand, no significant effect was observed in the kidney or small intestine of CUL-treated mice. A correlation between the effects of the various treatment modalities (on tumors, kidney, and small intestine) and the retention of cisplatin was found.

Animals↗
PubMed1994

A cranial invasion model of human neuroblastoma using congenitally athymic mice.

Even though the current limits of treatment for advanced stage neuroblastoma require an understanding of biology and new therapeutic approaches, few invasion models of human neuroblastoma (HNB) which evaluate experimental therapies have been reported. We describe herein a reproducible murine model of cranial invasion after the intraocular xenograft of HNB in congenitally athymic mice. Approximately 10 weeks after the intraocular injection of 5 x 10(6) NB-1 HNB cells, 70% (14/20) of the mice developed intracranial invasion with skull involvement. There was no operative mortality. Macroscopically, deformities of the cranium were revealed in all 14 mice, 5 of which developed exophthalmos. Microscopically, cranial invasion mainly involved the extradural space, skull, and orbita; however, brain involvement could not be seen, indicating that the dura may act as a barrier. These invasive characteristics are very similar to those seen in humans; thus, we believe that this model provides a useful tool for evaluating the biology of, and new therapeutic approaches against, cranial invasion of neuroblastoma in vivo.

Animals↗
PubMed1994

Endobronchial metastasis from a primary uterine osteosarcoma in a patient with multiple myeloma: report of a case.

We present herein the case of a 75-year-old woman with multiple myeloma who underwent a left lower lobectomy for endobronchial metastasis from an uterine osteosarcoma. She had initially been admitted to our hospital for chemotherapy more than 1 year earlier, soon after which a primary uterine osteosarcoma was discovered and a total abdominal hysterectomy and bilateral salpingo-oophorectomy performed. One year after the operation, the patient developed hemoptysis. A flexible bronchofiberscopy demonstrated a polypoid mass obstructing the left basal bronchus, and computed tomographic scans showed three pulmonary nodules. Surgery was performed to control the hemoptysis. At thoracotomy, two metastatic nodules were identified in the left lower lobe, and the endobronchial extension of the tumor was resected en bloc with the left lower lobe. The tumor was diagnosed as lung metastasis from the uterine osteosarcoma. Although further lung tumors have recently appeared, the patient has remained well for the 3 years since her last operation without any hemoptysis.

Aged↗
PubMed1994

Central nervous system abnormalities in chromosome deletion at 11q23.

Two Japanese pediatric patients with terminal deletion of the long arm of chromosome 11 are described. Both had the morphological abnormalities of the 11q deletion syndrome, such as prominent epicanthal folds, broad flat nasal bridge with short, upturned nose, short philtrum with carp-shaped mouth, cardiac anomalies and nonprogressive moderate psychomotor developmental delay. Patient 1 is the first case to be reported with 11q deletion with serial magnetic resonance (MR) examinations of cerebral white matter. The initial MR imaging studies demonstrated multiple areas of T1 and T2 prolongation in the cerebral white matter in both patients at the ages of 2 5/12 and 2 1/12 years, respectively. A second MR imaging, performed 1 year after the first in Patient 1, demonstrated slight improvement of the lesions. Neither patient showed clinical deterioration. These results suggest that the lesions were caused by delayed myelination, rather than by demyelination. It is suggested that an unknown factor which is important for myelination is located on the long arm of chromosome 11: perhaps the neural cell adhesion molecule (NCAM).

Abnormalities, Multiple↗
PubMed1994

Generation of alloxan radical in rat islet cells: participation of NADPH: cytochrome P-450 reductase.

Cytotoxic actions of alloxan are thought to be caused by the hydroxyl radical (HO+) generated in a cyclic reaction involving alloxan and its reduction product, alloxan radical (HA+). The generation of HA+ and the oxidation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) were observed in the reaction system of alloxan with NADPH in the presence of purified NADPH: cytochrome P-450 reductase [EC 1.6.2.4] (fp2) from rat liver microsomes. Both the generation of HA+ and the oxidation of NADPH were increased with increasing the concentrations of alloxan or fp2. These results indicate that NADPH-linked HA+ generation was catalyzed by fp2. The HA+ was generated in the reaction of alloxan with a homogenate of rat islet cells. The generation of HA+ in the reaction of alloxan with the homogenate of rat islet cells was markedly diminished by an immunogloblin fraction (Ig) of anti-fp2 serum, but not by control-Ig. The anti-fp2-Ig also inhibited the generation of HA+ in the reaction system of alloxan with NADPH in the presence of fp2. When the homogenate of islet cells from phenobarbital-treated rats was used, the generation of HA+ was significantly increased in comparison with that from the control rats. However, the homogenate of islet cells from 3-methylcholanthrene-treated rats did not have such a stimulative effect. These results suggest that the reduction of alloxan to HA+ was catalyzed by fp2 presented in islet cells.

Alloxan↗
PubMed1994

A role of iron in lambda DNA strand breaks in the reaction system of alloxan with reduced glutathione: iron(III) binding to the DNA.

lambda DNA strand breaks were easily induced in a reaction system involving alloxan with reduced glutathione (GSH) in the presence of FeCl3 in a HEPES-NaOH buffer, pH 7.4. Increasing concentrations of FeCl3 in the reaction system caused DNA strand breaks in a concentration-dependent fashion, suggesting that iron is required to induce the DNA strand breaks. Catalase, scavengers of hydroxyl radicals (HO.) and iron-chelators almost completely inhibited the DNA strand breaks, but superoxide dismutase (SOD) did not do so, suggesting that the HO., formed by a Fenton-type reaction, was the species responsible for the DNA strand breaks. The addition of FeCl3 to the solution containing DNA caused the formation of a DNA-Fe(III) complex, in which Fe(III) was reduced by an alloxan radical (HA.) but not by a superoxide radical. Only when apotransferrin was added to the reaction mixtures before the addition of FeCl3, were both the DNA strand breaks and the reduction of Fe(III) strongly inhibited. These results suggest that the Fe(III) bound to DNA catalyzes the DNA strand breaks which may be caused by the generation of site-specific HO. via an HA.-dependent Fenton-type reaction.

Alloxan↗
PubMed1994

Novel antitumor sesquiterpenoids in Achillea millefolium.

Three new antitumor sesquiterpenoids, achimillic acids A, B and C, were isolated as methyl esters from Achillea millefolium and their structures were determined spectroscopically. The compounds were found to be active against mouse P-388 leukemia cells in vivo.

Animals↗
PubMed1994

Protective effect of rebamipide against hydrogen peroxide-induced hemorrhagic mucosal lesions in rat stomach.

Intragastric administration of 6% H2O2 induces gastric mucosal hemorrhagic lesions in rats. Intraperitoneal administration of rebamipide at 10 to 100 mg/kg dose-dependently prevented the H2O2-induced mucosal lesions. The fact that cimetidine, ranitidine and omeprazole could not prevent the gastric mucosa from developing H2O2-induced lesions indicates that acid secretion might not be the main cause of these lesions. The protective effect of rebamipide was partially reduced by indomethacin and completely blocked by diethyl maleate, a glutathione depressor. Gastric mucosal glutathione level and glutathione peroxidase and superoxide dismutase (SOD) activities were significantly decreased by 6% H2O2 instillation. Rebamipide at 100 mg/kg significantly inhibited the decreases in gastric mucosal glutathione level and SOD activity. These results suggest that H2O2-induced gastric mucosal lesions might partially involve a decrease in defense activities against reactive oxygen species and that the protective effect of rebamipide might be related to its ability to improve oxidative stress in gastric mucosa.

Alanine↗