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.

Hydroxyapatite and bFGF Coating of Detachable Coils for Endovascular Occlusion of Experimental Aneurysm.

SUMMARY: The purpose of this study was to evaluate the effect of hydroxyapatite (HAp) and fibroblast growth factor-basic (bFGF) coating on Guglielmi detachable coils (GDCs) in an experimental aneurysm model. A total of 18 aneurysms were experimentally made in the common carotid arteries of swine. Embolization was done on these aneurysms using standard GDCs and coated GDCs with HAp (GDC-HAp) and with bFGF (GDC-HAp-bFGF). The animals were then killed 14 days after embolization. The development of tissue scarring and coverage the aneurysm's orifice were evaluated macroscopically. No significant difference of volume ratio of the coils exited in each groups. Macroscopically, covering ratio of fibrous membrane at the neck of aneurysms were 88.3 +/- 14.7% in a group with GDC-HAp-bFGF, while it were 26.7 +/- 15.3% in a group with standard GDC and it was 41.7 +/- 31.7% in a group with GDC-HAp. These results indicated that coating by hydroxyapatite and bFGF might facilitate a wound healing in an experimental aneurysm model.

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.

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.

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.

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.

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.

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.

Hydroxyapatite coating of detachable coils for endovascular occlusion of experimental aneurysm.

SUMMARY: The purpose of this study was to evaluate the effect of hydroxyapatite (HAp) coating on Guglielmi detachable coils (GDCs) in an experimental aneurysm model. A total of 12 aneurysms were experimentally made in the common carotid arteries of swine using a microsurgical technique. Embolization was done on these aneurysms using standard GDCs and GDCs coated with HAp (GDC-HAp). The animals were then killed 14 days after embolization. The physical properties of coated coils and the development of tissue scarring and coverage the aneurysm's orifice were evaluated macroscopically and microscopically. Macroscopically, a scar formation and coverage at the neck of aneurysms were observed in a group with GDC-HAp, while such findings were not seen in a group with GDC. With light microscope, fibroblasts were seen in the neck of the aneurysms in a group using GDC-HAp, whereas only a fibrin- like net was seen in a group using GDC. In a group with GDC-HAp, inflammatory response was more intense in the dome of the aneurysm with faster re-endothelial coverage of the neck of the aneurysm than the ones in a group with GDC. These results indicated that GDC-HAp might create a clinically beneficial biological surface in an experimental aneurysm model.