Hydroxyapatite is a calcium phosphate bioceramic that has been shown by many authors to be biocompatible with bioactive properties. It is widely accepted as the best synthetic material available for surgical use as a bone graft substitute. HA granules produced by AMREC-SIRIM from local materials underwent 5 types of sterilisation techniques with different ageing periods. Samples were tested for chemical and phase composition and microbial contamination before and after being sterilised. From the microbiological tests done, none of the unsterilised positive control yielded a positive culture. Results from X-Ray diffraction studies found that all the sterilisation techniques did not chemically degrade or structurally change the HA granules significantly.
Bacteriological Techniques ; Bone Substitutes/*analysis ; Calcium Phosphates/*analysis ; Materials Testing/*methods ; Sterilization/*methods ; X-Ray Diffraction

OBJECTIVETo develop a novel drug dilivery system based on calcium phosphate cement (CPC) with methotrexate (MTX) as a model drug and to study its drug release in vitro.

METHODSThree MTX mass fractions (0.1%, 0.2%, and 0.5%) were tested after solidification, and the compound of CPC-MTX were put into the simulated body fluid at 37 degrees C. The concentration of MTX was tested by high-performance liquid chromatography at day 2, 5, 10, 16 hours, 1, 2, 3, 5, 8, 10, 15, 20, 25, 30, 35, 40, and 45 days. The drug dilivery curves were drawn and drug dilivery rules were analyzed.

RESULTSMTX was released slowly and stably from the compound of CPC-MTX. Remarked prophase of drug release was noted, which conformed with the Higuchi equation. The drug release rate and concentration was related with the concentration of MTX in compound but not with the thickness and shape of CPC. The releasing time was not affected by the concentration of MTX.

CONCLUSIONA stable drug dilivery system can be developed by loading proper concentration of MTX into CPC.

Calcium Phosphates ; chemistry ; Chromatography, High Pressure Liquid ; Delayed-Action Preparations ; Kinetics ; Methotrexate ; administration & dosage ; analysis

The aim of this study was to elaborate a dense, strong and thin calcium-phosphate coating on commercial porous pure titanium implant surface in the light of a fast biomimetic procedure. After being polished, sandblasted, cleaned and treated with the mixture of HF and HNO3, the titanium plates were divided into two groups, namely group A and group B. The specimens of group A were free from any treatment. The specimens of group B were treated with the mixture of 48% H2SO4 and 18% HCl. All specimens soaked in SBF-A solution for 1d. Then the specimens were immersed in the SBF-B solution for 2 d. A thin calcium-phosphate coating was deposited on all the specimens of the two groups, the surface consisted of well-formed crystals, which were proved to be the mixture of hydroxycarbonated apatite (HCA) and octacalcium phosphate (OCP); the coating's Ca/P rate was 1.51. A thin carbonated calcium-phosphate coating was deposited on porous pure titanium by the use of the fast biomimetic procedure.
Biomimetic Materials ; analysis ; chemistry ; Calcium Phosphates ; analysis ; chemistry ; Coated Materials, Biocompatible ; chemistry ; Crystallization ; Prostheses and Implants ; Surface Properties ; Titanium ; chemistry

OBJECTIVETo evaluate the feasibility of growing tissue-engineered cartilage using chondrocytes seeded onto a biodegradable porous bioceramic, the beta-tricalcium phosphate (beta-TCP).

METHODSA porous bioceramic template of beta-TCP was created in the shape of a disc. Chondrocytes isolated from rabbit articular cartilage were seeded on the beta-TCP template and then kept in rotatory cell culture system (RCCS) for 1 week prior to subcutaneous transplantation into athymic mice. The three-dimensional structure was well-maintained 16 weeks after implantation. After 4, 8, 16 weeks, the specimens were harvested and examined macroscopically, histologically and immunohistochemically.

RESULTSGross morphological and histological analysis of the specimens from the chondrocyte-beta-TCP complex demonstrated new cartilage construction. The overall configuration of the experimental specimens closely resembled the structure of beta-TCP template.

CONCLUSIONThese findings suggest that porous bioceramic (beta-TCP) is a good "matrix" for chondrocyte, and can be used for cartilage engineering.

Animals ; Calcium Phosphates ; pharmacology ; Cartilage ; growth & development ; transplantation ; DNA ; analysis ; Female ; Glycosaminoglycans ; analysis ; Immunohistochemistry ; Mice ; Mice, Nude ; Tissue Engineering

calcium phosphate ceramic that has widely been used as a bone material to repair bone defects. Despite many clinical studies, the molecular mechanism whereby this biomaterial alters the gene expression in osteoblasts to promote bone formation is poorly understood. Thus, we attempted to address this question by using microarray techniques to identify the genes that are differentially regulated in osteoblasts exposed to beta-TCP.METHODS: By using DNA microarrays, we identified several genes whose expression levels were significantly up- or down-regulated in osteoblast-likeMG-63cells cultured with beta-TCP at a concentration of 100 mg/10 ml for 24 hours.RESULTS: The differentially expressed genes covered a broad range of functional activities: signal transduction, transcription, cell cycle regulation, vesicular transport, apoptosis, immunity, cytoskeletal elements and cell proliferation and differentiation.CONCLUSION: The gene expression changes related to cell proliferation and differentiation, vesicle transport, immunity and defense could affect the osteogenic activities of osteoblasts for bone regeneration. However, further studies will be required to verify the relative importance of these genes in bone formation, their temporal and spatial expression patterns and their interactions with each other.]]>
Apoptosis ; Bone Regeneration ; Calcium ; Calcium Phosphates ; Cell Cycle ; Cell Proliferation ; Ceramics ; Durapatite ; Gene Expression ; Microarray Analysis ; Oligonucleotide Array Sequence Analysis ; Osteoblasts ; Osteogenesis ; Signal Transduction

PURPOSE: The purpose of the present study was to determine the risk factors for predicting the recurrence in first-time urinary stone formers. MATERIALS AND METHODS: A total of 121 patients, who presented at our hospital with first-time urinary stone episodes, between 1996 and 2005, and followed up for at least 3 years, were retrospectively evaluated. Of these, 65 patients (41 males, 24 females) recurred (R group) and 56 (38 males, 18 females) not (NR group) during the follow-up period. The blood chemistry and urinary analytes values, as well as the clinical characteristics between the NR and R groups were compared by gender. p-values less than 0.05 were used to indicate statistical significance. RESULTS: There were no differences in the clinical characteristics between the NR and R groups. A comparison of the blood chemistry showed differences in the phosphate and calcium in men and women (p=0.047 and 0.034), respectively. Greater urinary excretion of phosphates were found in the R group than in the NR group (p=0.018), but was more prominent in men (p=0.006). No significant differences were found between the two groups with regard to metabolic abnormalities. A multivariate analysis revealed that urinary phosphates excretion was the sole predictor for stone recurrence (Exp beta=8.347, p=0.033). CONCLISIONS: Our results suggested that the increased excretion of urinary phosphates was a significant risk factor for stone recurrence, which might be useful as a prognostic marker.
Calcium ; Chemistry ; Female ; Follow-Up Studies ; Humans ; Male ; Multivariate Analysis ; Phosphates ; Recurrence* ; Retrospective Studies ; Risk Factors ; Urinary Calculi

PURPOSE: We evaluated the influence of urinary stone components on the outcomes of ureteroscopic removal of stones (URS) by electrohydraulic lithotripsy (EHL) in patients with distal ureteral stones. MATERIALS AND METHODS: Patients with a single distal ureteral stone with a stone size of 0.5 to 2.0 cm that was completely removed by use of EHL were included in the study. Operating time was defined as the time interval between ureteroscope insertion and complete removal of ureteral stones. Ureteral stones were classified into 5 categories on the basis of their main component (that accounting for 50% or more of the stone content) as follows: calcium oxalate monohydrate (COM), calcium oxalate dihydrate, carbonate apatite (CAP), uric acid (UA), and struvite (ST). RESULTS: A total of 193 patients (131 males and 62 females) underwent EHL. The mean operating time was 25.1+/-8.2 minutes and the mean stone size was 1.15+/-0.44 cm. Calcium oxalate stones accounted for 64.8% of all ureteral stones, followed by UA (19.7%), CAP (8.3%), and ST (7.2%) stones. The mean operating time was significantly longer in the UA group (28.6+/-8.3 minutes) than in the COM group (24.0+/-7.8 minutes, p=0.04). In multivariate analyses, the stone size was negatively associated with the odds ratio (OR) for successful fragmentation. UA as a main component (OR, 0.42; 95% confidence interval, 0.20 to 0.89; p=0.023) was also found to be significantly important as a negative predictive factor of successful fragmentation after adjustment for stone size. CONCLUSIONS: The results of the present study suggest that successful fragmentation by URS with EHL could be associated with the proportion of the UA component.
Accounting ; Apatites ; Calcium Oxalate ; Carbon ; Humans ; Lithotripsy ; Magnesium Compounds ; Male ; Multivariate Analysis ; Odds Ratio ; Phosphates ; Ureter ; Ureteroscopes ; Ureteroscopy ; Uric Acid ; Urinary Calculi

Bone mass is important for dental implant success and is regulated by mechanoresponsive osteocytes. We aimed to investigate the relationship between the levels and orientation of tensile strain and morphology and orientation of osteocytes at different dental implant positions in the maxillary bone. Bone biopsies were retrieved from eight patients who underwent maxillary sinus-floor elevation with β-tricalcium phosphate prior to implant placement. Gap versus free-ending locations were compared using 1) a three-dimensional finite-element model of the maxilla to predict the tensile strain magnitude and direction and 2) histology and histomorphometric analyses. The finite-element model predicted larger, differently directed tensile strains in the gap versus free-ending locations. The mean percentage of mineralised residual native-tissue volume, osteocyte number (mean ± standard deviations: 97 ± 40/region-of-interest), and osteocyte shape (~90% elongated, ~10% round) were similar for both locations. However, the osteocyte surface area was 1.5-times larger in the gap than in the free-ending locations, and the elongated osteocytes in these locations were more cranially caudally oriented. In conclusion, significant differences in the osteocyte surface area and orientation seem to exist locally in the maxillary bone, which may be related to the tensile strain magnitude and orientation. This might reflect local differences in the osteocyte mechanosensitivity and bone quality, suggesting differences in dental implant success based on the location in the maxilla.
Biopsy ; Bone-Implant Interface ; Calcium Phosphates ; pharmacology ; Dental Implants ; Finite Element Analysis ; Humans ; Maxilla ; surgery ; Osteocytes ; physiology ; Radiography, Panoramic ; Sinus Floor Augmentation ; Tensile Strength

The distribution and function of transforming growth factor-beta (TGF-beta) in the region of bone defect repaired by collagen/nano-beta-tricalcium phosphate composite artificial bone (Co/N-TCP) and the ability of Co/N-TCP recruiting osteoblasts to precipitate the repair of bone defect were investigated. Twenty-four domestic rabbits were operated on bilateral cranial bone to create an experimental bone defect of 8.0 mm in diameter through the whole bone. On the left, Co/N-TCP was implanted as experimental group, but on the right, Co/TCP was implanted as control group. At 2nd, 4th, 8th, 12th week after operation, all animals were sacrificed and the implanted materials with surrounding bone were taken out. Immunohistochemical staining was performed for TGF-beta assay by avidin-biotin complex method (SABC). Simultaneously, TGF-beta was quantitatively analyzed by HPIAS-1000 imaging analysis system. The immunohistochemical staining for TGF-beta revealed that osteoblasts and immature osteocytes highly expressed TGF-beta. Diffused TGF-beta positive staining particles appeared in the mesenchymal and fibrous-tissue. There was no significant difference in the TGF-beta positive staining between two groups in the medial region to original osseous beds at different time points (P > 0.05). However, in distal original osseous bed of the defected region, the positive expression of TGF-beta in the Co/N-TCP group was significantly stronger than in the control group (P < 0.05 or 0.01). The Co/N-TCP has good bioactivities and ability of stimulating and conducting TGF-beta to aggregate and precipitate the healing of bone defect.
Animals ; Biocompatible Materials ; therapeutic use ; Calcium Phosphates ; Ceramics ; Collagen ; Fracture Healing ; Implants, Experimental ; Nanotechnology ; Osseointegration ; drug effects ; Osteogenesis ; physiology ; Rabbits ; Skull Fractures ; metabolism ; surgery ; Transforming Growth Factor beta ; analysis ; metabolism

PURPOSE: This study aimed to assess the accuracy of low-dose dual-energy computed tomography (DECT) in predicting the composition of urinary calculi. MATERIALS AND METHODS: A total of 52 patients with urinary calculi were scanned with a 128-slice dual-source DECT scanner by use of a low-dose protocol. Dual-energy (DE) ratio, weighted average Hounsfield unit (HU) of calculi, radiation dose, and image noise levels were recorded. Two radiologists independently rated study quality. Stone composition was assessed after extraction by Fourier transform infrared spectroscopy (FTIRS). Analysis of variance was used to determine if the differences in HU values and DE ratios between the various calculus groups were significant. Threshold cutoff values to classify the calculi into separate groups were identified by receiver operating characteristic curve analysis. RESULTS: A total of 137 calculi were detected. FTIRS analysis differentiated the calculi into five groups: uric acid (n=17), struvite (n=3), calcium oxalate monohydrate and dihydrate (COM-COD, n=84), calcium oxalate monohydrate (COM, n=28), and carbonate apatite (n=5). The HU value could differentiate only uric acid calculi from calcified calculi (p<0.001). The DE ratio could confidently differentiate uric acid, struvite, calcium oxalate, and carbonate apatite calculi (p<0.001) with cutoff values of 1.12, 1.34, and 1.66, respectively, giving >80% sensitivity and specificity to differentiate them. The DE ratio could not differentiate COM from COM-COD calculi. No study was rated poor in quality by either of the observers. The mean radiation dose was 1.8 mSv. CONCLUSIONS: Low-dose DECT accurately predicts urinary calculus composition in vivo while simultaneously reducing radiation exposure without compromising study quality.
Adult ; Apatites/analysis ; Calcium Oxalate/analysis ; Female ; Humans ; Image Interpretation, Computer-Assisted/methods ; Kidney Calculi/chemistry/pathology/*radiography ; Magnesium Compounds/analysis ; Male ; Middle Aged ; Phosphates/analysis ; Prospective Studies ; Radiation Dosage ; Tomography, X-Ray Computed/methods ; Ureteral Calculi/chemistry/pathology/*radiography ; Uric Acid/analysis ; Waist Circumference ; Young Adult