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Biomedical subjects

A Kishida

Publications and source records attributed to A Kishida.

At least 19 recordsLinked to original sources
PubMed2004

Nano-scaled hydroxyapatite/polymer composite I. Coating of sintered hydroxyapatite particles on poly(gamma-methacryloxypropyl trimethoxysilane)grafted silk fibroin fibers through chemical bonding.

The inorganic-organic composite consisting of nano-scaled hydroxyapatite (HAp) and silk fibroin (SF) fibers was prepared through covalent linkage to develop a novel biomaterial for a soft-tissue-compatible material. The preparation of the composite was conducted through the three-step procedure consisting of chemical modification using 2-methacryloxyethyl isocyanate (MOI) monomer to introduce vinyl groups on SF, poly(gamma-methacryloxypropyl trimethoxysilane) (MPTS) graft-polymerization on SF, and coupling process between the surface of polyMPTS-grafted SF and HAp nano-particles. The amount of the graft-polymerization of polyMPTS through vinyl groups was well controlled by the reaction time. The nano-crystals were subsequently coated on the grafted fibers by heating at 120 degrees C for 2 h in a vacuum. The crystalline structure of the SF substrate did not change in the procedure. In the SEM observation of the composite surface, it was found that the bonded nano-crystals were separated and partially aggregated with several crystals attached on the SF fiber surface. The HAp particles adhered more strongly on the SF surface with separation or aggregation of several crystals than on the surface of the original SF after ultrasonic treatment.

Animals↗
PubMed2001

Cellular distribution of thrombomodulin as an early marker for warm ischemic liver injury in porcine liver transplantation: protective effect of prostaglandin I2 analogue and tauroursodeoxycholic acid.

BACKGROUND: Warm ischemia of the graft from non-heart-beating donors is considered a risk factor for posttransplant graft dysfunction. The early administration of cytoprotective agents may help improve graft dysfunction. METHODS: Four groups of 10 pigs each underwent orthotopic liver transplantation. Prostaglandin I2 analogue, OP-41483, was administered intraportally 30 min before warm ischemic insult in donors and after reperfusion in recipients in one group. In the other study group, additional intravenous tauroursodeoxycholic acid (TUDC) was given before the warm ischemic insult in donors and after reperfusion, then maintained continuously until postoperative day (POD) 7. RESULTS: Exposure of liver grafts to warm ischemia resulted in severe congestion with the disappearance of thrombomodulin (Tm) from the sinusoidal endothelial cells (SECs) and smooth muscle cells (SMCs) around biliary epithelial cells (BEpCs) 2 hr after reperfusion, followed by positive immunoreactivity of Tm in BEpCs with hyperbilirubinemia, which was related to high mortality. Combined administration of OP-41483 and TUDC had a protective effect, demonstrated by sustained immunoreactivity of Tm from SECs and SMCs until POD 7, without that reactivity in BEpCs. This was associated with reduced congestion and hyperbilirubinemia, similar to the control group not subjected to warm ischemia. CONCLUSIONS: These findings suggest that negative immunoreactivity of Tm in SECs and SMCs surrounding BEpCs and positive in BEpCs may be an early marker for ischemic liver injury, and that OP-41483 and TUDC may protect against the microcirculatory and biliary derangement.

Animals↗
PubMed2001

Techniques available for the management of massive sacrococcygeal teratomas.

An infant born in the 34th week of gestation weighing 5,355 g with a massive sacrococcygeal (SC) tumor was delivered by elective cesarean section. An ultrasonographic examination showed solid and cystic components in the tumor. Resection was successfully undertaken with insertion of a Nélaton catheter into the rectum to avoid unnecessary impairment of the viscera. The tumor weighed 2,380 g, measured 25 x 14 x 11 cm, and was clinicopathologically diagnosed to be a SC teratoma. This experience and other publications show that several considerations including control of hemorrhage and coagulopathies, visceral protection, and avoidance of wound infection are necessary to facilitate the surgical management of massive SC tumors. Several suggestions are made concerning the pre- and intraoperative management of this rare tumor.

Female↗
PubMed2001

Apatite coating on hydrophilic polymer-grafted poly(ethylene) films using an alternate soaking process.

Previously, we developed a novel alternate soaking process and clarified that bone-like apatite was formed on/in organic polymer hydrogel matrices using this process. The present study focused on the apatite coating on hydrophilic polymer grafted poly(ethylene) (PE) films with various grafting densities and commonly used hydrophilic polymers, poly(acryl amide) (PAAm) and poly(acrylic acid) (PAAc) were employed. From X-ray diffraction analysis, hydroxyapatite was coated on PAAm- or PAAc- grafted PE films. The amount of apatite coated on PAAm-grafted PE (PAAm-g-PE) films increased with an increase in the reaction cycles and the grafting density of PAAm. Similar to PAAm-g-PE, the amount of apatite coated on PAAc-grafted PE (PAAc-g-PE) films increased linearly with an increase in the grafting density of the PAAc up to around 30 microg/cm2. While, no significant increase in the apatite coating on the PAAc-g-PE films was observed even after 50 reaction cycles when the grafting densities of PAAc were over 30 microg/cm2. Apatite coating was not observed on original PE films. Scanning electron microscopic images reveal that the aggregation of apatite crystals on all PAAm-g-PE films and PAAc-g-PE films with grafting density from 10 to 30 microg/cm2. On the other hand, a dense apatite layer with some cracks was coated when the grafting density of the PAAc chains was over 30 microg/cm2. These results indicated that it was possible to coat apatite on hydrophilic polymer grafted PE films by an alternate soaking process and that the apatite crystal morphology could be controlled as a function of polymer type and density.

Apatites↗
PubMed2001

Study of cell-material interaction by estimating NF-kappaB activation in HeLa S3 cells adhered onto hydrophilic substrates.

In order to interpret how cells recognize biomaterials, nucleic factor-kappa B (NF-kappaB) activation in the attached HeLa S3 cells on various substrates was evaluated. As substrates, materials of hydrophilic nature (cellulose, poly(acrylamide)-grafted poly(ethylene) (PAAm-g-PE), and lipids films) were used. The contemporary assay method for NF-kappaB was modified to fit our system. As a result, NF-kappaB activation varied depending on the substrates. The NF-kappaB outcome was induced significantly in the HeLa S3 cells that had adhered onto the lipid films in a short time. On the other hand, high levels of NF-kappaB induction were observed in the HeLa cells adhered to the celluose and PAAm-g-PE after a 24 h incubation period. The induction of NF-kappaB by cell-material interaction is discussed from the point of view of biocompatibility.

Cell Adhesion↗
PubMed2001

HSP 47 and collagen mRNA expression in L929 cells adhered to lipid films.

L929 cell adhesion on various lipid films prepared by Langmuir-Blodgett methods (LB method) were studied. L929 cells adhered to every lipid film similar to tissue culture poly(styrene) (TCPS). The mRNA expression of both collagen and HSP47 in adherent cells were evaluated by the RT-PCR method. mRNA expression of collagen was not altered during adhesion and proliferation duration, while HSP47 mRNA expression changed depending on culture time. L929 cells adhered to L-alpha-dipalmitoylphosphatidylcholine (DPPC)-films showed little HSP47 mRNA expression. It was suggested that DPPC films regulate L929 cell function via unique serum protein adsorption.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2001

Urinary 8-oxo-7, 8-dihydro-2'-deoxyguanosine and biopyrrins levels among construction workers with asbestos exposure history.

It has been suggested that oxidative stress is associated with the cancers caused by asbestos. Since construction workers are sometimes exposed to low levels of asbestos, we investigated whether oxidative stress was elevated in construction workers who had been exposed to low levels of asbestos. The subjects were 48 Japanese construction workers. The defined asbestos-exposed group consisted of subjects who had the history of suspected exposure to asbestos and were diagnosed to have irregular opacities or pleural plaques. We measured the amount of 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) and biopyyrins in the urine of the subjects. The results showed that 8-oxodG and biopyyrins levels in the defined asbestos-exposed group were higher, although they were not statistically significant, than those in the control group. In addition, the urinary 8-oxodG levels tended to correlate positively with the duration of suspected exposure to asbestos. These results suggest that even low-level asbestos exposure may induce oxidative stress and that the resulting's the oxidative stress might be related to lung cancer in construction workers.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2001

Moderate alcohol consumption reduces urinary 8-hydroxydeoxyguanosine by inducing of uric acid.

Recent studies suggest that moderate alcohol consumption is associated with a low risk of cancer, coronary heart disease, and other diseases. Most of these diseases are considered to be related to the action of reactive oxygen species (ROS) at certain stages of disease progression. However, considerable evidence exists indicating that ethanol generates ROS in vivo. Thus, the reduced risk of disease as a result of alcohol consumption seems to contradict evidence suggesting the induction of ROS by ethanol. In the present study, we investigated whether oxidative stress was induced in moderate alcohol drinkers. We measured the total urinary biopyrrins and 8-hydroxydeoxyguanosine (8-OHdG) levels as a systemic oxidative stress marker and an oxidative DNA damage marker, respectively. Serum uric acid was also measured as an alcohol-induced antioxidant. We compared total urinary biopyrrins and 8-OHdG levels among groups with different alcohol habits. The results showed that total biopyrrins levels increased with the amount of alcohol consumed, but that the level of 8-OHdG significantly decreased with the amount of alcohol consumed. The decrease in 8-OHdG levels seemed to be associated with increasing levels of uric acid. Judging from the increasing level of total biopyrrins, alcohol may induce ROS. ROS may then cause cell damage in liver, as suggested by the positive correlation between the total biopyrrins levels and the serum GOT, GPT, and gammaGTP levels. However, since ROS may be more effectively counteracted by uric acid in organs other than the liver, DNA damage may be suppressed rather than induced. Accordingly, moderate alcohol consumption seems to have the overall effect of reducing DNA damage, as shown by the decrease in urinary 8-OHdG levels observed in our study.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2000

Preparation and characterization of apatite deposited on silk fabric using an alternate soaking process.

Apatite-deposited silk fabric composite materials were developed using a new alternate soaking process. The characteristics of deposited apatite were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FTIR), and X-ray photoelectron spectroscopy (XPS). Apatite weight increased with alternating soaking in a calcium solution [200 mM aqueous calcium chloride solution buffered with tris(hydroxymethyl) aminomethane and HCl (pH 7.4)] and a phosphate solution (120 mM aqueous disodium hydrogenphosphate) changed every hour. SEM showed that apatite deposited after 21 or more repeated soakings was over 20 microm thick. XRD showed that with alternate soakings, the apatite crystals deposited on silk fabric elongated along the c axis. FTIR and XPS indicated the existence of carbonate, HPO(4)(2-), and Na(+) ions in addition to constituent ions of hydroxyapatite. A loss of HPO(4)(2-) and Na(+) ions in the deposit upon further soaking might be associated with an increasing apatite crystallinity. Apatite deposited on silk by the alternate soaking process was a deficient apatite containing carbonate, HPO(4)(2-), and Na(+) ions as in a natural bone tissue. Thus, this apatite-silk composite material might be potentially bioactive.

Animals↗
PubMed2000

Polymyxin B binds to anandamide and inhibits its cytotoxic effect.

Anandamide (ANA), an endogenous cannabinoid, can be generated by activated macrophages during endotoxin shock and is thought to be a paracrine contributor to hypotension. We discovered that ANA in saline/ethanol solution and in serum was efficiently adsorbed in a polymyxin B (PMB)-immobilized beads column and eluted with ethanol. We confirmed the direct binding of PMB to ANA by using surface plasmon resonance. The adsorption of ANA by PMB may abolish the diverse effects of ANA such as hypotension, immunosuppression, and cytotoxicity, and may suggest a new therapeutic strategy for endotoxin shock.

Adsorption↗
PubMed2000

Prolongation of canine liver allograft survival by a novel immunosuppressant, FTY720: effect of monotherapy and combined treatment with conventional drugs.

BACKGROUND: The immunosuppressive effect and other properties of a novel immunosuppressant, FTY720, have been studied mostly in the experimental transplantation of various extrahepatic organs. In this experiment, we evaluated the antirejection potency and adverse effects of this agent on liver grafts using a canine liver transplantation model. METHODS: Forty-eight orthotopic liver transplantations were performed by the standard technique under a veno-venous bypass. Liver recipients were divided into two studies: a single-dose study with FTY720 at various doses and a combined dose study with conventional immunosuppressants (cyclosporine or tacrolimus) alone and combined with FTY720. Survival, biochemical and hematological tests, blood levels of immunosuppressants, and postmortem histology were determined. RESULTS: The median survival of untreated control animals was 9 days, whereas treatment with FTY720 at a dose of 0.1 mg/kg/day prolonged graft survival to 49.5 days. FTY720 at 1 mg/kg/day showed a slight but insignificant prolongation to 16 days, but when the dose was increased to 5 mg/kg/day, the graft was rejected at 10 days. The combination of FTY720, 0.1 mg/kg/day, with a subtherapeutic dose of cyclosporine, 5 mg/kg/ day, prolonged median animal survival from 40 days with cyclosporine alone to 74 days. A combination of FTY720 (0.1 mg/kg/day) with tacrolimus (0.5 mg/kg/ day) compromised animal survival, reducing survival from 83.5 days with tacrolimus alone to 30.5 days due to infectious complication and emaciation by overimmunosuppression. No evident drug-induced side effects were observed. CONCLUSIONS: FTY720 has a potent immunosuppressive effect when used alone at 0.1 mg/kg/day in canine liver transplantation. FTY720 is a promising candidate for future clinical application in orthotopic liver transplantation.

Animals↗
PubMed2000

Study on complex formation between recombinant human thrombomodulin fragment and thrombin using surface plasmon resonance.

Human thrombomodulin (hTM) is a newly described endothelial cell associated protein that functions as a potent natural anticoagulant by converting thrombin from a procoagulant protease to an anticoagulant. The affinity constant of recombinant human soluble TM (rhs-TM) and a peptide containing active site of hTM fragment (f-hTM) with thrombin were determined using the surface plasmon resonance. The interaction of f-hTM with thrombin could be analyzed by a simple model, whereas the association and the dissociation steps of rhs-TM with thrombin consisted of at least two kinds of interaction phases. The dissociation constant for complex (K(D)) of f-hTM and thrombin was determined to be 205 nM, which was more than twice as high as that of rhs-TM (6.7 and 75 nM). The lower affinity of f-hTM was not due to the slow association rate but to the rapid dissociation rate. It comes clear that f-hTM interacts with thrombin rapidly.

Humans↗
PubMed2000

Evaluation of biological responses to polymeric biomaterials by RT-PCR analysis IV: study of c-myc, c-fos and p53 mRNA expression.

In order to investigate how cells recognize biomaterials, mRNA that was expressed in attached human fibroblasts on various substrates was evaluated. The expressed oncogenes (c-fos and c-myc) and tumor suppressor gene (p53) mRNA were then isolated and detected using the RT-PCR method. As a result, c-fos and c-myc mRNA expression varied with respect to differences in the hydrophilicity-hydrophobicity of the substrates. Both c-fos and c-myc mRNA expression were low in the fibroblasts that had adhered to hydrophilic surfaces. The tendency of c-fos mRNA expression was similar to the adhesion curve of the cells. c-myc mRNA was largely induced in fibroblasts that had adhered to hydrophobic surfaces. p53 mRNA were largely induced in fibroblasts that had adhered to hydrophilic surfaces, while in the cells that had adhered to hydrophobic surfaces, p53 mRNA expression was low. We concluded that the expression of oncogenes and p53 mRNA is a powerful method for studying cell-polymer interactions or the evaluation of the carcinogenic activity of biomaterials.

Biocompatible Materials↗
PubMed2000

A novel hydroxyl radical scavenger, nicaraven, protects the liver from warm ischemia and reperfusion injury.

BACKGROUND: Reactive oxygen species have been considered to be involved in liver injury at the procurement, preservation, and transplantation from donors without beating hearts. A novel hydroxyl radical scavenger, nicaraven with hydrophilic and lipophilic properties, infiltrates both intracellular and extracellular spaces where it effectively scavenges reactive oxygen species. Protection by nicaraven against ischemia and reperfusion damage of the brain, heart, and kidneys has been shown. The effect of this agent on the liver remains unclear. METHODS: Two-hour total hepatic vascular exclusion was used. Eighteen beagle dogs were randomly assigned to 2 groups: 12 animals were not treated (group I) and 6 were treated with nicaraven (group II). Nicaraven was administered intravenously (2mg/kg/min) for 60 minutes before ischemia and for 3 hours, starting 30 minutes before reperfusion. RESULTS: Two-week survival rates were 25% in group I and 100% in group II (P <.01). Nicaraven inhibited lipid peroxidation in the liver, improved hepatic and systemic hemodynamics and energy metabolism, and suppressed liver enzyme release, endothelin-1 elevation in hepatic venous blood, histologic damage, and neutrophil infiltration into the liver. CONCLUSIONS: Nicaraven exerted hepatic protection against warm ischemia and reperfusion injury. This may indicate nicaraven as a potential candidate to attenuate liver injury from warm ischemia and preservation in transplantation from donors without beating hearts.

Adenine Nucleotides↗
PubMed2000

Study of cellular responses to polymeric biomaterials using the differential display method.

In this study, we attempted to detect altered gene expressions in the cells that had adhered to various surfaces using the differential display method. Thioglycollate-elicited peritoneal exudate cells (PEC) and mouse fibroblast (L929) cells were cultured on the polymer films. After a predetermined time, the total RNA was isolated from cells and the differential mRNA expressions were evaluated by RT-PCR method. As a result, in the differential display of amplified cDNA from PEC, the different patterns of cDNA fragments among the samples were obtained. This indicates that there were many different mRNA expressions depending on the polymer surfaces. The use of differential method was proven to be useful for studying cell-polymer interaction.

Animals↗