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Biomedical subjects

K Kawanabe

Publications and source records attributed to K Kawanabe.

At least 37 records · Page 2Linked to original sources
PubMed1998

A-W glass ceramic as a bone substitute in cemented hip arthroplasty: 15 hips followed 2-10 years.

We retrospectively reviewed hip arthroplasties in 13 patients (15 hips), in whom we had used apatite-wollastonite (A-W) glass ceramic together with auto- or allograft for augmentation of severe bone deficiency. 11 cemented sockets and 4 stem revisions were included and followed for 2-9.6 years. There were no radiolucent lines between A-W glass ceramic and surrounding bone, and remodeling of the bone graft containing A-W glass ceramic was observed. No migration of cemented sockets was seen except in 1 case, which was revised. In this case, direct bonding between bone and A-W glass ceramic granules was present histologically. In 4 stem revisions, 5 mm subsidence occurred in 1 case. However, the stem became stable and remodeling of the grafted bone occurred. An artificial bone material, such as A-W glass ceramic, can be used under high-load conditions, because of its good mechanical properties.

Adult↗
PubMed1997

Simultaneous determination of cysteine sulfinic acid and hypotaurine in rat tissues by column-switching high-performance liquid chromatography with electrochemical detection.

Cysteine sulfinic acid (CSA) and hypotaurine (HT) were determined by electrochemical detection with a glassy carbon electrode at 0.95 V vs. Ag/AgCl. The separation of CSA and HT was accomplished by coupled-column liquid chromatography, consisting of an anion-exchange column and a cation-exchange column. For the determination of CSA and HT in rat tissues, a column-switching system was introduced to remove interferences from late-eluting endogenous substances. The limits of determination were 0.05 microM for both sulfinic acids. The average precisions (C.V.) over the concentration range of 0.05 to 5 microM were 4.3% for CSA and 4.2% for HT.

Animals↗
PubMed1997

Apatite layer-coated titanium for use as bone bonding implants.

For development of thin bioactive coatings on metal implants, a dense and uniform apatite layer was coated onto titanium (Ti) implants in situ by using a new biomimetic method, which is composed of apatite nucleation and growth steps in simulated body fluid (SBF). Analysis of the coatings by thin film X-ray diffraction and scanning electron microscopy-energy dispersive X-ray microanalysis (SEM-EMPA) before implantation showed that its characteristics were very similar to those of natural bone. The coated and uncoated rectangular plates were bilaterally implanted into the tibial proximal metaphyses of rabbits. After 6, 10 and 25 weeks post-implantation, the bone bonding and bone formation at the bone-implant interfaces were evaluated by a detachment test and undecalcified histological examination. Mechanical testing in tension showed that the failure load of apatite layer-coated Ti implants was significantly higher than that of uncoated control at each time period (all P < 0.001). Histologically, it was shown that bone was deposited directly onto the apatite coating without any intervening soft tissue, while in the paired controls, interpositional soft tissue was seen at the bone-implant interface. By SEM-EPMA, a uniform calcium- and phosphorus-rich layer was detected between the coated implants and bone, but not in uncoated controls at either earlier or later time periods. The results indicate that the apatite layer deposited on Ti in situ may significantly increase the bone bonding strength by providing a bioactive surface, which allows for an early bone apposition to the implant. In addition, the apatite layer-coated Ti produced by the biomimetic process may fulfil the requirements of favourable thin coatings and strong adhesion at the metal-coating interface.

Analysis of Variance↗
PubMed1997

Fatal pulmonary embolism after total hip arthroplasty. Three Japanese cases.

It has been reported that the incidence of postoperative pulmonary embolism is significantly lower in Asians than in Westerners, however, several recent reports have cited an increase in the incidence in Asia. We have experienced three cases of fatal pulmonary embolism after total hip replacement in Japanese patients. Our three patients had received no preoperative prophylaxis, even though they had risk factors for pulmonary embolism. Prophylaxis for pulmonary embolism seems necessary in Asian patients who are at risk.

Adult↗
PubMed1997

Severe metallosis caused by shaving down of the stem neck due to outer cup impingement of a bipolar endoprosthesis. A case report. off.

The authors report on a patient with severe metallosis caused by shaving down of the stem neck due to outer cup impingement. A primary arthroplasty was performed using an Omnifit bipolar endoprosthesis (Stryker) with an acetabular bone graft fixed by ceramic screws. At the time of revision surgery the synovium was stained black. Two ceramic screws were broken, but no scratch was observed on the metal surfaces of the outer cup and the inner head. The ultra-high molecular weight polyethylene (UHMWPE) of the inner-bearing collar was worn and flat. During the operation, a groove was observed at the stem neck where the outer cup impinges. An analysis of the black pseudocapsule by scanning electron microscopy with electron prove microanalysis (SEMEPMA) revealed that the pseudocapsule contained titanium metal particles. To our knowledge, metallosis caused by the same mechanism has only been reported in four joints, which were replaced by a Zimmer BHP bipolar endoprosthesis and Howmedica bicentric cup.

Female↗
PubMed1996

Mechanical and biological properties of two types of bioactive bone cements containing MgO-CaO-SiO2-P2O5-CaF2 glass and glass-ceramic powder.

In this study two types of bioactive bone cement containing either MgO-CaO-SiO2-P2O5-CaF2 glass (type A) or glass-ceramic powder (type B) were made to evaluate the effect of the crystalline phases on their mechanical and biological properties. Type A bone cement was produced from glass powder and bisphenol-a-glycidyl methacrylate (BIS-GMA) resin, and type B from glass-ceramic powder containing apatite and wollastonite crystals and BIS-GMA resin. Glass or glass-ceramic powder (30, 50, 70, and 80 by wt %) was added to the cement. The compressive strength of type A (153-180 MPa) and B (167-194 MPa) cement were more than twice that of conventional polymethylmethacrylate (PMMA) cement (68 MPa). Histological examination of rat tibiae showed that all the bioactive cements formed direct contact with the bone. A reactive layer was seen at the bone-cement interface. In specimens with type A cement the reactive layer consisted of two layers, a radiopaque outer layer (Ca-P-rich layer) and a relatively radiolucent inner layer (low-calcium-level layer). With type B cement, although the Ca-P-rich layer was seen, the radiolucent inner layer was absent. Up to 26 weeks there was progressive bone formation around each cement (70 wt %) and no evidence of biodegradation. The mechanical and biological properties of the cements were compared with those of a previously reported bone cement containing MgO-free CaO-SiO2-P2O5-CaF2 glass powder (designated type C).

Animals↗
PubMed1996

Intercalary replacement of canine femora using a new bioactive bone cement.

We have developed a bioactive bone cement (BA cement) consisting of Bis-GMA resin and bioactive glass powder. It has high compressive and tensile strengths, a low curing temperature and its bioactivity allows it to bond directly with bone. We operated on the 18 femora of nine mongrel dogs for intercalary replacement of part of the bone by a metal prosthesis using either PMMA cement or BA cement for fixation. Three dogs were killed at each of 4, 12 and 26 weeks after surgery for the evaluation of fixation strength by a push-out test and for histological examination by Giemsa surface staining and SEM. Fixation strengths with PMMA cement at 4, 12 and 26 weeks after surgery were 46.8 +/- 18.9, 50.0 +/- 24.7, and 58.2 +/- 28.9 kgf (mean +/-sD), respectively. Those with BA cement were 56.8 +/- 26.1, 67.2 +/- 19.2, and 72.8 +/- 22.2 kgf, respectively. Fibrous tissue intervened between bone and PMMA cement but BA cement had bonded directly to bone at 12 and 26 weeks. This suggests that BA cement will be useful in providing long-lasting fixation of implants to bone under weight-bearing conditions.

Animals↗
PubMed1995

Bioactive bone cement: the effect of amounts of glass powder and histologic changes with time.

A study was conducted to examine the influence of the amount of glass powder added to a bioactive bone cement of our formula on its mechanical and biologic properties. Serial changes in the cement with time were also examined. The bioactive bone cement consisted of CaO-SiO2-P2O5-CaF2 glass powder and bisphenol-a-glycidyl methacrylate resin. Glass powder was added to the cement in 30, 50, 70, and 80% weight ratios. The compressive strengths of the resulting cements (171-239 MPa) were more than double that of polymethylmethacrylate cement (68 MPa). Histologic examination of rat tibiae bearing artificial defects packed with each bioactive cement showed direct bone contact 4 weeks after surgery. The cement with a higher percentage of glass powder showed better direct formation of bone around its periphery with a thicker reactive layer. Under scanning electron microscopic observation, the reactive layer showed increased levels of calcium and phosphorus. Examination of histologic changes up to 26 weeks showed progressive bone formation around the cement and no sign of biodegradation.

Animals↗
PubMed1993

A new bioactive bone cement consisting of BIS-GMA resin and bioactive glass powder.

We have developed a bioactive bone cement consisting of silane-treated CaO-SiO 2-P 2O 5-CaF 2 glass powder as the filling particles and bisphenol-a-glycidyl methacrylate (BIS-GMA) diluted with triethylene-glycol dimethacrylate (TEGDMA) as the organic matrix. Histological examination demonstrated direct bonding between the cement and bone along the circumference of the cement at 4 weeks after implantation in rat tibia. The compressive strength and toughness of the cement were two and four times greater than those of polymethylmethacrylate (PMMA) cement, respectively. The inflammatory reaction of the skin caused by the new cement was not as intense as that for PMMA 3 days after subcutaneous implantation. This new cement may be applicable as a bioactive bone cement with high mechanical strength.

Animals↗
PubMed1992

Acute nephrotoxicity as an adverse effect after intraperitoneal injection of massive amounts of bioactive ceramic powders in mice and rats.

Silicon elution from bioactive ceramic powders was measured using an in vitro solubility test, in which the powders were soaked in phosphate buffer solution. Silicon elution was highest in Bioglass (BG), followed by Ceravital (KGS), apatite-wollastonite-containing glass ceramics (A-W.GC), and hydroxyapatite (HA), respectively. Silicon elutions on this in vitro solubility test were correlated with the rates of rapid death in mice following intraperitoneal injection of each of these bioactive ceramic powders. Histopathological examination of the mice revealed nephropathy, which was considered to be the cause of death. The nephropathy was characterized by epithelial degeneration in the renal tubules and increased silicon content throughout the entire kidney, findings suggesting silicon nephropathy. It is considered that, because a large quantity of silicon eluted from the powder was absorbed from the peritoneum, concentration in the glomerular filtrate and urine increased until silicon polymerization occurred, after which the silicon polymer became deposited in the renal tubules. A single injection of furosemide prevented the acute nephrotoxicity of bioactive ceramic powder.

Animals↗
PubMed1992

High performance liquid chromatographic determination of bound sulfide and sulfite and thiosulfate at their low levels in human serum by pre-column fluorescence derivatization with monobromobimane.

A sensitive and specific high performance liquid chromatographic method for the determination of sulfide, sulfite, and thiosulfate was established. Inorganic sulfur anions were converted into fluorescent derivatives with monobromobimane. The derivatives were separated on a coupled column chromatography with a reversed-phase octadecyl silica column connected with a weakly basic anion exchanger column by isocratic elution with acetic acid solution (pH 3)-acetonitrile (13:3, v/v) containing 25 mM NaClO4. The method was applied to the determination of bound sulfide and sulfite and thiosulfate in normal human serum. Thiosulfate could be determined directly by use of an ultrafiltered sample. For the determination of bound sulfide and sulfite, the pretreatment step with continuous flow gas dialysis was effective for the sample after releasing sulfide and sulfite by reduction with dithiothreitol. The limits of quantification by the present method were 0.05 microM for thiosulfate, 0.5 microM for bound sulfide, and 0.2 microM for bound sulfite.

Bridged Bicyclo Compounds↗
PubMed1992

Enhancement of bone bonding to bioactive ceramics by demineralized bone powder.

In an attempt to enhance the bonding of bone to bioactive ceramics, allogeneic demineralized bone powder (DBP) was used in combination with bioactive ceramic implants in rabbit tibiae. Rectangular plates (10 x 15 x 2 mm) made of apatite-wollastonite-containing glass ceramics were implanted in the proximal metaphyses of the bilateral tibiae of 20 rabbits, with DBP packed into the medullary cavity. In the control group, only the plates of A-W GC were implanted in the bilateral tibiae of 20 rabbits. Four rabbits from each group were killed at two, four, eight, 12, and 25 weeks after implantation for the tensile test. Results of the tensile test and histologic examination of the undecalcified specimens by Giemsa surface stain and contact microradiography confirmed that DBP significantly accelerated the process of bone bonding to the implant and increased the strength of bone-implant bonding.

Animals↗
PubMed1991

Effects of injecting massive amounts of bioactive ceramics in mice.

The effects of massive administration of bioactive ceramic powder (Bioglass (45S5), Ceravital (KGS), apatite-wollastnite containing glass ceramics (A-W GC), and hydroxyapatite (HA], by intraperitoneal (IP), intramuscular (IM), or subcutaneous (SC) injection in Balb/c mice were examined in this investigation. Alumina, Silica Glass (SG), and A-W-Al (containing the same amount of crystal as A-W GC and 6.3% Alumina) were used as nonbioactive controls. The particle size of each material injected was smaller than 44 microns. In addition to the above, two more sizes (smaller than 105 microns and smaller than 255 microns) of A-W GC powder, and a 1 x 1 x 0.2 cm plate of the A-W GC were also evaluated. When the particle size was smaller than 44 microns, intraperitoneal injections of 5 mg per g of body weight of BG, KGS, A-W GC, and A-W-Al were lethal to the mice. Ceramics in fine powder form, which are generally believed to have higher bioactivity, are associated with higher mortality except A-W-Al. On the other hand, when the particle size of the ceramic was increased, the fatal effects of ceramic powders in mice decreased. Plate form of ceramics implanted I.P. had no systemic effects. Intramuscular or SC injections of bioactive ceramic powder with a particle size smaller than 44 microns had almost no systemic effects. Both the particle size of the ceramic powder and the route of administration influenced the reactivity of the bioactive ceramics in the mice. In conclusion, regardless of particle size, neither SC nor IM injection of large doses of highly bioactive ceramics had an adverse effect on the host (mouse).

Animals↗
PubMed1991

Improved method for measurement of rhodanese activity using methanethiosulfonate as sulfur donor substrate and its application to human serum.

We have developed a sensitive method for the measurement of rhodanese activity in human serum which is based on the colorimetric method for the determination of thiocyanate produced from methanethiosulfonate and cyanide as substrates. Thiocyanate gives a red complex with ferric ion in an acidic condition. The present method is about 70-fold more sensitive than the conventional method using cyanide and thiosulfate as substrates and correlates well (r = 0.997) with the conventional method in bovine liver rhodanese. Within-run precision of the method is 0.91% for 420 units/l serum and the calibration curve is linear up to 1850 units/l. The normal value for human serum, determined by the present method on 31 healthy persons, was 20.9 +/- 20.0 units/l (mean +/- 2S.D.). Rhodanese activity was clearly elevated in some serum samples which were observed at abnormal values in some biochemical diagnostic tests and showed significant positive correlations with guanase activity (r = 0.728, p less than 0.01) and glutamic-oxalacetic transaminase activity (r = 0.625, p less than 0.01).

Humans↗
PubMed1991

Changes in causes of visual handicaps in Tokyo.

Newly registered visually handicapped patients at the Tokyo Metropolitan Rehabilitation Center for the Physically and Mentally Handicapped were studied in 1968 (when the facility was opened), 1978, and 1988. Examinations were carried out by the same physicians and diagnoses were made by uniform criteria. Since approximately 10% of the total population of Japan lives in Tokyo, the statistics on the causes of visual handicaps in this area deserve to be reported. The changes observed over the past twenty years are as follows: There were few changes in the percentages of high myopia, retinal degeneration and senile cataract. The percentages of corneal opacity, retinopathy of prematurity, congenital cataract and optic atrophy decreased, while those of diabetic retinopathy, glaucoma and retinal macular degeneration increased. Advances in medical treatment and the shift into an aging society in Japan are responsible for these changes observed.

Adolescent↗
PubMed1990

Enzymatic assay of 3-mercaptopyruvate sulfurtransferase activity in human red blood cells using pyruvate oxidase.

A highly sensitive method has been developed for the determination of 3-mercaptopyruvate sulfurtransferase (EC 2.8.1.2) activity in human red blood cells which is based on the colorimetric method for the determination of pyruvate using the coupled color enzymatic reaction with pyruvate oxidase (EC 1.2.3.3) and peroxidase (EC 1.11.1.7). The absorbance increase of the coupled color of N-ethyl-N-(2-hydroxy-3-sulfopropyl)-m-toluidine and 4-aminoantipyrine at 555 nm is proportional to sulfurtransferase activity. The present method is more than 10-fold more sensitive and more reproducible than the usual methods, and does not require centrifugation, filtration, and neutralization steps. The calibration curve is linear up to 450 units/liter and the precision per run is 1.06% for 77.5 units/10(10) red blood cells (n = 10). Comparison with the lactate dehydrogenase method gave good correlation (r = 0.995). The normal value for the human red blood cell enzyme, determined with the present method on 30 healthy persons, was 63.8 +/- 14.4 units/10(10) cells (mean +/- 2SD).

Colorimetry↗