Mechanisms and treatment of extruding intraconal implants: socket aging and tissue restitution (the "Cactus Syndrome").

Arch Ophthalmol. 2007 Dec;125(12):1616-20

Authors: Sagoo MS, Rose GE

OBJECTIVE: To investigate the initial features and treatment of 26 consecutive patients referred with extruding orbital implants between January 1991 and December 2004. METHODS: Retrospective medical record review recording the reason for enucleation, primary implant type, infection when initially seen, time to implant exposure, location of conjunctival defect, and time to surgical revision. RESULTS: Of the 26 eyes, 16 (62%) were removed after trauma, 3 (12%) because of tumor, 3 (12%) because of infection, and 4 (15%) because of painful blind eyes (percentages do not total 100 because of rounding). Of the 26 eyes, 8 (31%) were right eyes and 15 (58%) were hemispheric implants; 8 implants (31%) were acrylic or glass spheres, and 1 (4%) each was a hydroxyapatite, porous polythene, or bone sphere. Hemisphere extrusion occurred at a mean of 16 years after implantation, significantly later than with spheres (mean, 10 years after implantation; P = .05). The conjunctiva was breached medially in only 1 (sphere) (4%), centrally in 13 (50%), and laterally in 12 (46%). Lateral erosion occurred solely with hemispheres, in contrast to central erosions, in which 10 of 13 (77%) were spheres (P < .001). Twelve patients (46%) underwent surgical revision within a year of extrusion, 7 (27%) within 2 years, and the remaining 7 (27%) at 2 to 21 years. CONCLUSIONS: Exposure of hemispheres occurred later, from pressure erosion at their prominent lateral edge. In contrast, central erosion (in spheres) occurred earlier, because of gradual tissue restitution after forced-ball implantation ("cactus syndrome"). This may be avoided by implantation through a polythene glide.

PMID: 18071110 [PubMed - in process]

Induction and high density culture of human hepatoblasts from fetal hepatocytes with suppressing transformation.

Biol Pharm Bull. 2007 Dec;30(12):2308-11

Authors: Kiyota A, Matsushita T, Ueoka R

It is well known that it would be important to cultivate human hepatocytes of about 10(10) cells at a high cell density, about 1 x 10(7) cells/cm(3), in the bioreactor for the development of bioartificial liver. However, since primary human hepatocytes lack an ability to proliferate in vitro, it is essential to establish a culture method for the proliferation of normal human hepatic stem cells as a cell source. In this study, it was found that human hepatoblasts, a kind of hepatic stem cells, were induced from human fetal hepatocytes while keeping the ability of proliferation by the treatment of 1mM sodium butyrate (SB) for 12 d of culture. The transformation of hepatoblasts was evaluated by abnormal prothrombin (PIVKA-II) assay, which is a clinical marker for hepatocellular carcinoma. The PIVKA-II production rate of the cells was suppressed to the normal level under 1 mM SB. The cells including hepatoblasts under 1 mM SB attached to the porous hydroxyapatite carriers and proliferated to a high cell density of about 1 x 10(7) cells/cm(3) in the carriers. The liver-specific function, cytochrome P450 3A4 activity (4.2 pmol/mg protein/min) of the cells in the carriers under 1 mM SB was comparable to that of primary human hepatocytes. Ammonia metabolizing activity (0.21 micromol/10(6) cells/h) of the cells was also comparable to that of porcine hepatocytes used in the bioartificial liver. The PIVKA-II production rate of the cells in the carrier was suppressed to the normal level. These results suggested that induction of human hepatoblasts from fetal hepatocytes by the treatment of 1mM SB and proliferation of the cells at a high cell density using hydroxyapatite carriers should be one of the more promising culture methods for bioartificial liver developments.

PMID: 18057717 [PubMed - in process]

Morphological and chemical analysis of bone substitutes by scanning electron microscopy and microanalysis by spectroscopy of dispersion energy.

Braz Dent J. 2007;18(2):129-33

Authors: Cruz GA, Toledo S, Sallum EA, Lima AF

This study evaluated the morphological and chemical composition of the following bone substitutes: cancellous and cortical organic bovine bone with macro and microparticle size ranging from 1.0 to 2.0 mm and 0.25 to 1.0 mm, respectively; inorganic bovine bone with particle size ranging from 0.25 to 1.0 mm; hydroxyapatite with particle size ranging from 0.75 to 1.0 mm; and demineralized freeze-dried bone allograft with particle size ranging from 0.25 to 0.5 mm. The samples were sputter-coated with gold in an ion coater, the morphology was observed and particle size was measured under vacuum by scanning electron microscopy (SEM). The chemical composition was evaluated by spectroscopy of dispersion energy (EDS) microanalysis using samples without coating. SEM analysis provided visual evidence that all examined materials have irregular shape and particle sizes larger than those informed by the manufacturer. EDS microanalysis detected the presence of sodium, calcium and phosphorus that are usual elements of the bone tissue. However, mineral elements were detected in all analyzed particles of organic bovine bone except for macro cancellous organic bovine bone. These results suggest that the examined organic bovine bone cannot be considered as a pure organic material.

PMID: 17982552 [PubMed - in process]

Improved success of sparse matrix protein crystallization screening with heterogeneous nucleating agents.

PLoS ONE. 2007;2(10):e1091

Authors: Thakur AS, Robin G, Guncar G, Saunders NF, Newman J, Martin JL, Kobe B

BACKGROUND: Crystallization is a major bottleneck in the process of macromolecular structure determination by X-ray crystallography. Successful crystallization requires the formation of nuclei and their subsequent growth to crystals of suitable size. Crystal growth generally occurs spontaneously in a supersaturated solution as a result of homogenous nucleation. However, in a typical sparse matrix screening experiment, precipitant and protein concentration are not sampled extensively, and supersaturation conditions suitable for nucleation are often missed. METHODOLOGY/PRINCIPAL FINDINGS: We tested the effect of nine potential heterogenous nucleating agents on crystallization of ten test proteins in a sparse matrix screen. Several nucleating agents induced crystal formation under conditions where no crystallization occurred in the absence of the nucleating agent. Four nucleating agents: dried seaweed; horse hair; cellulose and hydroxyapatite, had a considerable overall positive effect on crystallization success. This effect was further enhanced when these nucleating agents were used in combination with each other. CONCLUSIONS/SIGNIFICANCE: Our results suggest that the addition of heterogeneous nucleating agents increases the chances of crystal formation when using sparse matrix screens.

PMID: 17971854 [PubMed - in process]

Effect of hydroxyapatite coating on risk of revision after primary total hip arthroplasty in younger patients: findings from the Danish Hip Arthroplasty Registry.

Acta Orthop. 2007 Oct;78(5):622-8

Authors: Paulsen A, Pedersen AB, Johnsen SP, Riis A, Lucht U, Overgaard S

BACKGROUND: The effect of hydroxyapatite (HA) on implant survival in the medium and long term is uncertain. We studied the effect of HA coating of uncemented implants on the risk of cup and stem revision in primary total hip arthroplasty (THA). PATIENTS AND METHODS: Using the Danish Hip Arthroplasty Registry (DHR), we identified patients less than 70 years old who had undergone uncemented primary THA during 1997-2005. 4,125 HA-coated and 7,737 non-HA-coated cups and 3,158 HA-coated and 4,749 non-HA-coated stems were available for analysis. The mean follow-up time was 3.4 years for cups and 3.2 years for stems. We estimated the relative risk (RR) of revision due to aseptic loosening or any cause, and adjusted for possible confounders (age, sex, fixation of opposite implant part, and diagnosis for primary THA) using multivariate Cox regression analysis. RESULTS: The adjusted RRs for revision of HA-coated cups and stems due to aseptic loosening were 0.89 (95%CI: 0.37-2.2) and 0.71 (95%CI: 0.27-1.9) with up to 9 years of follow-up, compared to non-HA-coated implants. When taking all causes of revision into consideration, the risk estimates were 0.85 (95%CI: 0.68-1.1) and 0.81 (95%CI: 0.61-1.1) for HA-coated cups and stems, respectively. INTERPRETATION: In this medium-term follow-up study, the use of HA-coated implants was not associated with any clearly reduced overall risk of revision compared to non-HA-coated implants.

PMID: 17966021 [PubMed - indexed for MEDLINE]

Mag-seeding of rat bone marrow stromal cells into porous hydroxyapatite scaffolds for bone tissue engineering.

J Biosci Bioeng. 2007 Sep;104(3):171-7

Authors: Shimizu K, Ito A, Honda H

Bone tissue engineering has been investigated as an alternative strategy for autograft transplantation. In the process of tissue engineering, cell seeding into three-dimensional (3-D) scaffolds is the first step for constructing 3-D tissues. We have proposed a methodology of cell seeding into 3-D porous scaffolds using magnetic force and magnetite nanoparticles, which we term Mag-seeding. In this study, we applied this Mag-seeding technique to bone tissue engineering using bone marrow stromal cells (BMSCs) and 3-D hydroxyapatite (HA) scaffolds. BMSCs were magnetically labeled with our original magnetite cationic liposomes (MCLs) having a positive surface charge to improve adsorption to cell surface. Magnetically labeled BMSCs were seeded onto a scaffold, and a 1-T magnet was placed under the scaffold. By using Mag-seeding, the cells were successfully seeded into the internal space of scaffolds with a high cell density. The cell seeding efficiency into HA scaffolds by Mag-seeding was approximately threefold larger than that by static-seeding (conventional method, without a magnet). After a 14-d cultivation period using the osteogenic induction medium by Mag-seeding, the level of two representative osteogenic markers (alkaline phosphatase and osteocalcin) were significantly higher than those by static-seeding. These results indicated that Mag-seeding of BMSCs into HA scaffolds is an effective approach to bone tissue engineering.

PMID: 17964479 [PubMed - indexed for MEDLINE]

Novel molecules for intra-oral delivery of antimicrobials to prevent and treat oral infectious diseases.

Biochem J. 2008 Jan 15;409(2):601-9

Authors: Raj PA, Rajkumar L, Dentino AR

New molecules were designed for efficient intra-oral delivery of antimicrobials to prevent and treat oral infection. The salivary statherin fragment, which has high affinity for the tooth enamel, was used as a carrier peptide. This was linked through the side chain of the N-terminal residue to the C-terminus of a defensin-like 12-residue peptide to generate two bifunctional hybrid molecules, one with an ester linkage and the other with an anhydride bond between the carrier and the antimicrobial components. They were examined for their affinity to a HAP (hydroxyapatite) surface. The extent of the antimicrobial release in human whole saliva was determined using (13)C-NMR spectroscopy. The candidacidal activity of the molecules was determined as a function of the antimicrobial release from the carrier peptide in human saliva. The hybrid-adsorbed HAP surface was examined against Candida albicans and Aggregatibacter actinomycetemcomitans using the fluorescence technique. The bifunctional molecules were tested on human erythrocytes, GECs (gingival epithelial cells) and GFCs (gingival fibroblast cells) for cytotoxicity. They were found to possess high affinity for the HAP mineral. In human whole saliva, a sustained antimicrobial release over a period of more than 40-60 h, and candidacidal activity consistent with the extent of hybrid dissociation were observed. Moreover, the bifunctional peptide-bound HAP surface was found to exhibit antimicrobial activity when suspended in clarified human saliva. The hybrid peptides did not show any toxic influence on human erythrocytes, GECs and GFCs. These novel hybrids could be safely used to deliver therapeutic agents intra-orally for the treatment and prevention of oral infectious diseases.

PMID: 17919120 [PubMed - in process]

Purification and characterization of 45 kDa PAF acetylhydrolase from bovine colostrum.

Biol Pharm Bull. 2007 Sep;30(9):1668-73

Authors: Moon TC, Son SY, Chang HW

Platelet activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine; PAF) acetylhydrolase (PAF-AH) activity has been identified in bovine colostrum and high levels of this activity are found in early colostrum (within 24 h after parturition). In this study, PAF-AH in early colostrum was purified by ammonium sulfate precipitation, and sequential use of butyl-Toyopearl 650M, DEAE-Sepharose, heparin-Sepharose, hydroxyapatite, chelating-Sepharose and Mono Q HPLC column chromatography. This enzyme is a monomeric polypeptide with a molecular weight of approximately 45 kDa on 12.5% SDS-PAGE. The V(max) and K(m) for PAF-AH were 87.6 microM and 7.96 nmol/min/mg respectively. This enzyme was inhibited by phenylmethylsulfonyl fluoride, iodoacetamide and p-bromophenacylbromide, suggesting that both serine and histidine residues are required for enzyme activity. It was not inactivated by NaF or dithiothreitol. The purified enzyme did not degrade phospholipids with a long chain fatty acyl group at the sn-2 position. Accordingly, this enzyme is distinct from phospholipase A(2). In addition, PAF-AH selectively hydrolyzed oxidatively modified phosphatidylcholine. Furthermore, this enzyme was shown by Western blot analysis using antibody to human plasma PAF-AH to be plasma type PAF-AH. These results clearly demonstrate that 45 kDa plasma type PAF-AH activity exists in bovine colostrum.

PMID: 17827718 [PubMed - indexed for MEDLINE]

Antibiotic resistance in an in vitro subgingival biofilm model.

Oral Microbiol Immunol. 2007 Oct;22(5):333-9

Authors: Sedlacek MJ, Walker C

INTRODUCTION: The purpose of this study was to utilize an in vitro biofilm model of subgingival plaque to investigate resistances in subgingival biofilm communities to antibiotics commonly used as adjuncts to periodontal therapy. METHODS: Biofilms were grown on saliva-coated hydroxyapatite supports in trypticase-soy broth for 4 h-10 days and then exposed for 48 h to either increasing twofold concentrations of tetracycline, amoxicillin, clindamycin, and erythromycin or therapeutically achievable concentrations of tetracycline, doxycycline, minocycline, amoxicillin, metronidazole, amoxicillin/clavulanate, and amoxicillin/metronidazole. RESULTS: Concentrations necessary to inhibit bacterial strains in steady-state biofilms were up to 250 times greater than the concentrations needed to inhibit the same strains grown planktonically. In the presence of therapeutically available antibiotic concentrations, significantly higher proportions of the biofilms remained viable as the biofilms reached steady-state growth. The combinations of amoxicillin/clavulanate and amoxicillin/metronidazole were the most effective in suppressing growth. These combinations were particularly effective against biofilms up to and including 7 days of age and inhibited 90% or more of the bacteria present relative to untreated controls. As the biofilms approached steady state, these combinations were less effective with 50-60% of the bacteria retaining viability. CONCLUSION: Most, but not all, species of subgingival bacteria are considerably more resistant in biofilms than in planktonic cultures. Resistance appeared to be age-related because biofilms demonstrated progressive antibiotic resistance as they matured with maximum resistance coinciding with the steady-state phase of biofilm growth.

PMID: 17803631 [PubMed - in process]

Amniotic membrane transplantation for porous sphere orbital implant exposure.

J Zhejiang Univ Sci B. 2007 Sep;8(9):616-9

Authors: Chen YH, Cui HG

OBJECTIVE: This study is aimed at describing the clinical outcome of amniotic membrane transplantation for exposure of porous sphere implants. METHODS: A retrospective review of consecutive cases of porous sphere orbital implant exposure was carried out. Eight cases were presented between May 2004 and Oct. 2006 (5 males, 3 females; mean age 44.5 years). Six had enucleation and two had evisceration. Exposure occurred in two primary and six secondary. Orbital implant diameter was 22 mm in seven cases and 20 mm in one case. Six patients are with hydroxyapatite and two with high-density porous polyethylene (Medpor) orbital implants. The mean time from implantation to exposure was 1.1 months (range 0.8-2 months). All patients required surgical intervention. RESULTS: The time of follow-up ranged from 3.0 to 28.0 months (mean 16.5 months). Amniotic membrane grafting successfully closed the defect without re-exposure in all of these patients. The grafts were left bare with a mean time to conjunctiva of about 1 month (range 0.8-1.5 months). CONCLUSION: Exposed porous sphere implants were treated successfully with amniotic membrane graft in all of patients. The graft is easy to harvest. This technique is useful, dose not lead to prolonged socket inflammation and infection, and it is valuable application extensively.

PMID: 17726741 [PubMed - indexed for MEDLINE]

Ultrasound effect on osteoblast precursor cells in trabecular calcium phosphate scaffolds.

Biomaterials. 2007 Nov;28(32):4788-94

Authors: Appleford MR, Oh S, Cole JA, Protiv&#xED;nský J, Ong JL

This study investigated the in vitro effect of low-intensity pulsed ultrasound (LIPUS) on human embryonic palatal mesenchyme cells (HEPM, CRL-1486, ATCC, Manassas, VA), an osteoblast precursor cell line, during early adhesion to calcium phosphate scaffolds. Hydroxyapatite (HA) and beta-tricalcium phosphate (TCP) ceramic scaffolds were produced by a template coating method. Phospho-specific antibody cell-based ELISA (PACE) technique was utilized on stress activation proteins, including the extracellular signal-regulated kinase (ERK1/2), P38, c-Jun N-terminal kinase (JNK) and the anti-apoptosis mediator protein kinase B (PKB/AKT). Cell-based ELISAs were also performed on the membrane anchoring protein vinculin and alpha6beta4 integrin. LIPUS stimulated activation of PERK 1/2, PJNK, PP38 and vinculin in traditional two-dimensional (2-D) culture. Calcium release from the scaffolds was partially involved in the activation of PERK 1/2 when cell response was compared between culture on 2-D surfaces and three-dimensional (3-D) HA and TCP scaffolds. Effects of calcium extracted media from scaffolds alone could not account for the full activation of PJNK, PP38, PAKT, vinculin and alpha6beta4 integrin. LIPUS stimulation further increased PERK activity on TCP scaffolds corresponding with an increase in both vinculin and alpha6beta4 integrin levels. It was concluded from this study that LIPUS treatment can significantly affect stress signaling mediators and adhesion proteins in osteoblast precursor cells during the early cell-attachment phase to trabecular patterned scaffolds.

PMID: 17706764 [PubMed - indexed for MEDLINE]

Coronary calcification in patients with end-stage renal disease: a novel endocrine disorder?

Hormones (Athens). 2007 Apr-Jun;6(2):120-31

Authors: Efstratiadis G, Koskinas K, Pagourelias E

Cardiovascular mortality is significantly increased among patients with end-stage renal disease. The commonly observed vascular calcification in such patients has been considered as one of the causative factors. In patients undergoing dialysis, the incidence of coronary artery calcification is 2-5 times higher compared to patients with normal renal function and angiographically demonstrated coronary artery disease. Moreover, epidemiological studies have revealed a significant correlation of the extent of coronary artery calcification with the severity of underlying atherosclerotic lesions. Vascular calcification was initially considered as a passive process of hydroxyapatite deposition due to elevated plasma concentrations of calcium and phosphate. Nevertheless, there is a growing body of evidence that vascular calcification is an actively regulated and cell-mediated process. This phenomenon includes phenotypic alterations of vascular smooth muscle cells mainly resulting from an imbalance between promoters (such as increased Ca x P product) and inhibitors (fetuin-A, GLA protein, osteoprotegerin) of mineral deposition. With regard to the therapeutic approach, despite the evident effectiveness of both traditional and innovative remedies in the management of metabolic and electrolytic abnormalities of patients with end-stage renal disease, an individualized intervention based on etiopathogenesis is really required.

PMID: 17704043 [PubMed - indexed for MEDLINE]

Alveolar wound healing after implantation with a pool of commercially available bovine bone morphogenetic proteins (BMPs): a histometric study in rats.

Braz Dent J. 2007;18(1):29-33

Authors: Calixto RF, Te&#xF3;filo JM, Brentegani LG, Lamano-Carvalho TL

The capacity of a commercially available pool of bovine bone morphogenetic proteins (BMPs) to stimulate osteogenesis in the rat alveolar healing was investigated by histometric analysis. Male rats were anesthetized and had their upper incisor extracted. A pool of purified bovine BMPs adsorbed to microgranular resorbable hydroxyapatite was agglutinated with bovine collagen and saline before implantation into the alveolar socket. The implanted and control rats (n=30 per group) were sacrificed 1 to 9 weeks postoperatively, the hemi-maxillae were decalcified, processed for paraffin embedding and semi-serial longitudinal sections were obtained and stained with hematoxylin and eosin. The volume fraction of alveolar healing components was estimated by a differential point-counting method in histologic images. The results showed that in both, control and implanted rats, the alveolar healing followed the histologic pattern usually described in the literature. Quantitative data confirmed that the BMPs mixture did not stimulate new bone formation in the alveolar socket of implanted rats. These results suggest that the pool of BMPs adsorbed to hydroxyapatite and agglutinated with bovine collagen did not warrant incorporation of the osteoinductive proteins to a slow-absorption system that would allow a BMPs release rate compatible to that of new bone formation, and thus more adequate to osteoinduction.

PMID: 17639197 [PubMed - indexed for MEDLINE]

Preparation and characterization of multilayered hydroxyapatite/silk fibroin film.

J Biosci Bioeng. 2007 Jun;103(6):514-20

Authors: Kino R, Ikoma T, Yunoki S, Nagai N, Tanaka J, Asakura T, Munekata M

We prepared multilayered films consisting of silk fibroin (SF) and hydroxyapatite (HAp) by alternating lamination using untreated SF and HAp-deposited SF films. Untreated SF films were prepared from a regenerated SF solution by air drying. HAp-deposited SF films were prepared by soaking methanol-treated SF films containing >5 wt% CaCl2 in a simulated body fluid with the ion concentration 1.5-fold higher than that of the standard one. The multilayered HAp/SF films had HAp layers with approximate thicknesses of 3-5 microm and SF layers with thicknesses of 40-70 microm. The bonding strength between the SF and HAp layers was significantly affected by temperature and compression time under the lamination method. The optimal conditions for achieving the maximum T-peel strength and beta-sheet contents were determined to be 130 degrees C for 4 min. The Young's modulus of the multilayered films (133.4 MPa) was higher than that of the films consisting of SF alone (92.5 MPa) under swollen conditions. The biocompatibility of the HAp-deposited SF films was analyzed by culturing of osteoblasts (MC3T3-E1) on a film. The results indicate that HAp-deposited SF films and SF films show similar degrees of cell adhesion and alkaline phosphatase activities.

PMID: 17630122 [PubMed - indexed for MEDLINE]

Effect of bovine bone morphogenetic proteins on radius fracture healing in rabbits.

Acta Cir Bras. 2007 Jul-Aug;22(4):260-5

Authors: Lima AF, Rahal SC, Volpi Rdos S, Granjeiro JM, Taga R, Cestari TM

PURPOSE: To investigate the effect of bovine bone morphogenetic proteins (bBMPs) bound to hydroxyapatite plus collagen in the healing of unstable radius fractures. METHODS: A transverse fracture was induced at the mid of the diaphysis in both radii on 15 Norfolk rabbits with average age of 5.5 months and 3.5 kg. A mixture of bBMPs bound to thin powdered hydroxyapatite (bBMP-HA) and bovine collagen as agglutinant was applied to the right radius fracture site. The left radius fracture was considered control and no treatment was used. After 30, 60 and 90 days (5 rabbits/period) the rabbits were euthanized and the radii were collected for histological analysis. RESULTS: The descriptive histological analysis revealed that repair was similar for both forelimbs. The histomorphometric analysis showed that the mean area of newly formed bone was 867442.16 mm2, 938743.00 mm2 and 779621.06 mm2 for the control forelimbs, and 841118.47 mm2, 788038.76 mm2 and 618587.24 mm2 for the treated forelimbs at 30, 60 and 90 days, respectively. Thus the newly formed bone area was 12.17% larger in the forelimbs treated with bBMP-HA/collagen than in the control forelimbs (p<0.05, Tukey test) in the 60-day period after surgery. In both forelimbs the newly formed bone area increased throughout the experimental period until the complete fracture healing. CONCLUSION: Based on the result obtained here we concluded that bBMP-HA/collagen induced a lower but significant improvement in fracture consolidation.

PMID: 17625663 [PubMed - in process]

Effect of crystallization inhibitors on vascular calcifications induced by vitamin D: a pilot study in Sprague-Dawley rats.

Circ J. 2007 Jul;71(7):1152-6

Authors: Grases F, Sanchis P, Perell&#xF3; J, Isern B, Prieto RM, Fernández-Palomeque C, Torres JJ

BACKGROUND: Pathological calcification in soft tissues (ie, ectopic calcification) can have severe consequences. Hydroxyapatite is the common mineral phase present in all tissue calcifications. In general, the development of tissue calcifications requires a pre-existing injury as an inducer (heterogeneous nucleant), whereas further progression requires the presence of other promoter factors (such as hypercalcemia and/or hyperphosphatemia) and/or a deficiency in calcification repressor factors (crystallization inhibitors and cellular defense mechanisms). The present study investigated the capacity of etidronate (a bisphosphonate used in osteoporosis treatment) and phytate (a natural product) to inhibit vascular calcification in rats. METHODS AND RESULTS: Six male Sprague-Dawley rats in each of the 3 treatment groups were subcutaneously injected with either a placebo (physiological serum solution), etidronate (0.825 micromol x kg(-1) x day (-1)) or phytate (0.825 micromol x kg (-1) x day(-1)) for 8 days. Four days into this regimen, calcinosis was induced by subcutaneous injections of 500,000 IU/kg vitamin D at 0 h, 24 h and 48 h. Ninety-six hours after the final vitamin D injection, the rats were killed and aortas and their hearts were removed for histological and calcium analyses. The data showed that phytate-treated rats had lower levels of aortic calcium than placebo-treated rats. All groups had similar heart calcium levels. CONCLUSIONS: The present study found that phytate acted as a vascular calcification inhibitor. Thus, the action of polyphosphates could be important in protecting against vascular calcification.

PMID: 17587727 [PubMed - indexed for MEDLINE]

Osteoblast differentiation and bone formation gene expression in strontium-inducing bone marrow mesenchymal stem cell.

Kobe J Med Sci. 2007;53(1-2):25-35

Authors: Sila-Asna M, Bunyaratvej A, Maeda S, Kitaguchi H, Bunyaratavej N

Osteoblastic differentiation from human mesenchymal stem cell (hMSCs) is an important step of bone formation. We studied the in vitro induction of hMSCs by using strontium ranelate, a natural trace amount in water, food and human skeleton. The mRNA synthesis of various osteoblast specific genes was assessed by means of reverse transcription polymerase chain reaction (RT-PCR). In the hMSCs culture, strontium ranelate could enhance the induction of hMSCs to differentiate into osteoblasts. Cbfa1 gene was earlier expressed on day 4 of cell culture (the control group, on day 14) and osteonectin on day 11 (control, on day 21). The early Cbfa1 expression indicates that strontium could enhance osteoblastic differentiation. The detection of osteonectin using strontium induction indicates the role of strontium in enhancing bone remodeling, bone structure stabilization of hydroxyapatite molecule and collagen fibril organization. The cultured hMSCs in the presence of strontium expressed genes of bone extracellular matrix: collagen type I, bone sialoprotein and osteocalcin on the same days as control (same medium with no strontium). Concentration of strontium ranelate has been recommended to be optimized in between 0.2107 - 21.07 microg/ml whereas the high concentration up to 210.7 microg/ml have delayed effect on osteoblastic differentiation with delayed expression on Cbfa1 and osteonectin, and inhibitory effect on bone sialoprotein expression. In addition, strontium could help cell expansion by maintaining cell proliferation rate of hMSCs and osteoblast lineage. We recommend that the strontium is an important factor for inducing mesenchymal stem cells to differentiate into osteoblasts with further enhancement on bone formation. This model might provide a useful cell source for tissue engineering and bone repair.

PMID: 17579299 [PubMed - indexed for MEDLINE]

Effect of hydroxyapatite nanoparticles on the growth and p53/c-Myc protein expression of implanted hepatic VX2 tumor in rabbits by intravenous injection.

World J Gastroenterol. 2007 May 28;13(20):2798-802

Authors: Hu J, Liu ZS, Tang SL, He YM

AIM: To evaluate the effect of hydroxyapatite nano-particles (Nano HAP) by intravenous injection on the inhibition of implanted hepatic VX(2) tumor growth in rabbits and cell p53/c-Myc protein expression. METHODS: 60 hepatic VX(2) tumor-bearing rabbits was randomly divided into five groups. Nano HAP collosol 20 mg/kg, 40 mg/kg, 5-FU solutions 20 mg/mL, mixed liquor of 5-FU solution 20 mg/mL and Nano HAP collosol 20 mg/kg were infused by vein, normal saline conducted as the control. The general state, weight, liver function and gross tumor volume were detected dynamically. The expression of p53 and c-Myc gene protein in tumor tissue was detected by immunohistochemistry methods. RESULTS: The growth of implanted hepatic VX(2) tumors was significantly inhibited in all therapy groups, 3 wk after the injection, the tumor control rates in Nano HAP collosol groups were 25.5% and 32.5% respectively, and the gross tumor volumes were obviously less than that of control group. (24.81 +/- 5.17 and 22.73 +/- 4.23 vs 33.32 +/- 5.26, P<0.05). The tumor control rate of 5-FU group was 43.7% (18.74 +/- 4.40 vs 33.32 +/- 5.26, P<0.05), but the general state of the animals after injection aggravated; and the adverse reaction in the drug combination group obviously decreased. Due to the effect of Nano HAP, the positive expression of tumor associated the mutated p53 and c-Myc in tumor tissue was decreased obviously compared with the control group. CONCLUSION: Nano HAP has evident inhibitory action on rabbit implanted hepatic VX(2) tumor in vivo, which may be the result of decreasing the expression of the mutated p53 and c-myc, and drug combination can obviously decrease the adverse reaction of 5-FU.

PMID: 17569114 [PubMed - indexed for MEDLINE]

Mechanical response of porous scaffolds for cartilage engineering.

Physiol Res. 2007 May 31;

Authors: Jan&#x10D;ář J, Slovíková A, Amler E, Krupa P, Kecová H, Planka L, Gal P, Nečas A

Mechanical properties of scaffolds seeded with mesenchymal stem cells used for cartilage repair seem to be one of the critical factors in possible joint resurfacing. In this paper, the effect of adding hyaluronic acid, hydroxyapatite nanoparticles or chitosan nanofibers into the cross-linked collagen I on the mechanical response of the lyophilized porous scaffold has been investigated in the dry state at 37 oC under tensile loading. Statistical significance of the results was evaluated using ANOVA analysis. The results showed that the addition of hyaluronic acid significantly (p<<0.05) reduced slightly the tensile elastic modulus and enhanced the strength and deformation to failure of the modified cross-linked collagen I under the used test conditions. On the other hand, addition of hydroxyapatite nanoparticles and chitosan nanofibers, respectively, increased the elastic modulus of the modified collagen ten-fold and four-fold, respectively. Hydroxyapatite caused significant reduction in the ultimate deformation at break while chitosan nanofibers enhanced the ultimate deformation under tensile loading substantially (p<<0.05). The ultimate tensile deformation was significantly (p<<0.05) increased by addition of the chitosan nanofibers. The enhanced elastic modulus of the scaffold was translated into enhanced resistance of the porous scaffolds against mechanical load compared to scaffolds based on cross-linked neat collagen or collagen with hyaluronic acid with similar porosity. It can be concluded that enhancing the rigidity of the compact scaffold material by adding reinforcing chitosan nanofibers can improve the resistance of the porous scaffolds against compressive loading, which can provide more structural protection to the seeded mesenchymal stem cells when the construct is implanted into a lesion. Moreover, scaffolds with chitosan nanofibers seemed to enhance cell growth compared to the neat collagen I when tested in vitro as well as the scaffold stability extending its resorption to more than 10 weeks. This paper is scheduled for Physiological Research, Vol. 56, Supplement 1 (2007).

PMID: 17552899 [PubMed - as supplied by publisher]

[Ultrastrtctural observation of bone marrow stromal cells cultured in coralline hydroxyapatite]

Nan Fang Yi Ke Da Xue Xue Bao. 2007 May;27(5):705-7

Authors: Tu XL, Liu HW, Iwai Y, Kumabe S, Aikawa F

OBJECTIVE: To observe the ultrastructure of bone marrow stromal cells (BMSCs) cultured in coralline hydroxyapatite (CHA) and evaluate their biocompatibility. METHODS: BMSCs isolated from dogs were cultured with CHA as the scaffold, and the morphologies of the cells were observed with phase-contrast microscope and scanning electron microscope. RESULTS AND CONCLUSION: BMSCs grew well with good attachment to the CHA scaffold and performed normal function, demonstrating CHA as one of useful biocarrier materials for bone tissue engineering.

PMID: 17545094 [PubMed - in process]

An in vitro biofilm model of subgingival plaque.

Oral Microbiol Immunol. 2007 Jun;22(3):152-61

Authors: Walker C, Sedlacek MJ

INTRODUCTION: Numerous biofilm models have been described for the study of bacteria associated with the supragingival plaque. However, there are fewer models available for the study of subgingival plaque. The purpose of this study was to develop and validate a model that closely mimicked the composition of the subgingival flora. METHODS: The model was developed as follows: calcium hydroxyapatite disks were coated overnight with 10% sterile saliva, placed in flat-bottomed tissue culture plates containing trypticase-soy broth, directly inoculated with a small aliquot of dispersed subgingival plaque, incubated anaerobically, and transferred to fresh medium at 48-h intervals until climax (steady-state) biofilms were formed ( approximately 10 days). RESULTS: The model, based on samples from eight periodontitis patients and eight healthy subjects, yielded a multi-species, heterogeneous biofilm, consisting of both gram-positive and gram-negative species, and comprising 15-20 cultivable species associated with the subgingival flora. The species present and their proportions were reflective of the initial cultivable subgingival flora. Comparisons of the initial plaque samples from healthy subjects and the mature biofilms showed 81% similarity in species and 70% similarity in the proportions present. Biofilms formed from samples obtained from periodontally diseased subjects were 69% similar in species and 57% similar in the proportions present. CONCLUSIONS: The biofilm model described here closely reproduces the composition of the cultivable subgingival plaque both in the species present and in their relative proportions. Differences existed between biofilms grown from diseased and non-diseased sites with the former being characterized by the presence of periodontal pathogens at microbially significant levels.

PMID: 17488440 [PubMed - indexed for MEDLINE]

The effect of prism orientation on the indentation testing of human molar enamel.

Arch Oral Biol. 2007 Sep;52(9):856-60

Authors: Braly A, Darnell LA, Mann AB, Teaford MF, Weihs TP

Recent nanoindentation studies have demonstrated that the hardness and Young's modulus of human molar enamel decreases by more than 50% on moving from the occlusal surface to the dentine-enamel junction on cross-sectional samples. Possible sources of these variations are changes in local chemistry, microstructure, and prism orientation. This study investigates the latter source by performing nanoindentation tests at two different orientations relative to the hydroxyapatite prisms: parallel and perpendicular. A single sample volume was tested in order to maintain a constant chemistry and microstructure. The resulting data show very small differences between the two orientations for both hardness and Young's modulus. The 1.5-3.0% difference is significantly less than the standard deviations found within the data set. Thus, the variations in hardness and Young's modulus on cross-sectional samples of human molar are attributed to changes in local chemistry (varying levels of mineralization, organic matter, and water content) and changes in microstructure (varying volume fractions of inorganic crystals and organic matrix). The impact of prism orientation on mechanical properties measured at this scale by nanoindentation appears to be minimal.

PMID: 17449008 [PubMed - in process]

A pilot study with a therapeutic vaccine based on hydroxyapatite ceramic particles and self-antigens in cancer patients.

Cell Stress Chaperones. 2007;12(1):33-43

Authors: Ciocca DR, Frayssinet P, Cuello-Carri&#xF3;n FD

We describe an approach to produce an autologous therapeutic antitumor vaccine using hydroxyapatite (HA) for vaccinating cancer patients. The novel approach involved (1) the purification of part of the self-tumor antigens/ adjuvants using column chromatography with HA, (2) the employ of HA as a medium to attract antigen-presenting cells (APCs) to the vaccination site, and (3) the use of HA as a vector to present in vivo the tumor antigens and adjuvants to the patient's APCs. The vaccine was prepared using and combining HA particles, with at least 3 heat shock proteins (gp96 was one of them possibly with chaperoned proteins/peptides as shown in the slot blots) and with proteins from the cell membrane system (including Hsp70, Hsp27, and membrane proteins). The timing of HA degradation was tested in rats; the HA particles administered under the skin attracted macrophages and were degraded into smaller particles, and they were totally phagocytized within 1 week. In patients (n = 20), the vaccine was then administered weekly and showed very low toxicity, causing minor and tolerable local inflammation (erythema, papule, or local pain); only 1 patient who received a larger dose presented hot flashes, and there were no systemic manifestations of toxicity or autoimmune diseases attributed to the vaccine. Our study suggests that this therapeutic vaccine has shown some efficacy producing a positive response in certain patients. Stable disease was noted in 25% of the patients (renal carcinoma, breast carcinoma, and astrocytoma), and a partial response was noted in 15% of the patients (breast carcinoma and astrocytoma). The most encouraging results were seen in patients with recurrent disease; 4 patients in these conditions (20%) are disease free following the vaccine administration. However, we do not want to overstate the clinical efficacy in this small number of patients. The therapeutic vaccine tested in our study is working by activating the T-cell response as was shown in the comparative histological and immunohistochemical study performed in the pre- and postvaccine biopsy taken from a patient with inflammatory breast carcinoma. However, we cannot ruled out that the vaccine could also be producing an antibody(ies)-mediated response. In conclusion, this therapeutic vaccine based on HA ceramic particles and self-antigens can be safely administered and is showing some encouraging clinical results in cancer patients.

PMID: 17441505 [PubMed - indexed for MEDLINE]

The efficacy of methotrexate-impregnated hydroxyapatite composites on human mammary carcinoma cells.

J Orthop Surg (Hong Kong). 2007 Apr;15(1):56-61

Authors: Vechasilp J, Tangtrakulwanich B, Oungbho K, Yuenyongsawad S

PURPOSE: To investigate the efficacy of local biodegradable composites of hydroxyapatite, plaster of Paris, and a binder of either alginate or chitosan impregnated with methotrexate on human mammary carcinoma cells. METHODS: An in vitro analysis of drug dissolution and a cytotoxicity test on human mammary carcinoma cells were performed over one month. Physicochemical properties of each composite were investigated using scanning electron microscopy, X-ray diffractometry, and Fourier transform infrared spectroscopy. RESULTS: Both composites with a binder of either alginate or chitosan could release methotrexate for over one month. The amount of methotrexate released depended on the amount of methotrexate loaded. The composite using alginate as a binder released a significantly greater amount of methotrexate than that using chitosan as a binder (p<0.05). The elution of both composites showed favourable cytotoxicity when the concentration was greater than 5 microg/ml. CONCLUSION: Methotrexate-impregnated hydroxyapatite composites appear to be effective local skeletal methotrexate delivery systems against human mammary carcinoma cells in an in vitro model.

PMID: 17429119 [PubMed - indexed for MEDLINE]

[Preparation of cisplatin-impregnated coral hydroxyapatite drug delivery system]

Nan Fang Yi Ke Da Xue Xue Bao. 2007 Mar;27(3):283-5

Authors: Yang JC, Yin QS, Lin J, Huang HY, Ding HW, Zhang Y, Li J

OBJECTIVE: To prepare a cisplatin-impregnated coral-derived hydroxyapatite (CCHA) drug delivery system (DDS), and evaluate its inhibitory effect on human osteosarcoma cells U-2 OS, human breast cancer and prostatic carcinoma cells PC-3 in vitro. METHODS: The coral-derived hydroxyapatite (CHA) was manufactured by hydrothermal exchange and impregnated with cisplatin by vacuum freeze-drying techniques. The leaching solutions of this DDS was collected at different intervals in a course of 8 weeks and their inhibitory effect on the cells was tested in vitro by MTT assay. RESULTS: Electron microscope showed that cisplatin was distributed homogeneously in the pores of CHA. The inhibition rates of the leaching solution on all the tumor cells exceeded 50% except for PC-3 cells, whose inhibition rate was 29.92% when treated with the solution collected at the eighth week. CONCLUSION: CCHA allows sustained drug release and maintains excellent inhibitory effect on human bone tumor cells within 8 weeks in vitro.

PMID: 17425972 [PubMed - in process]

Development of a peptide-containing chewing gum as a sustained release antiplaque antimicrobial delivery system.

AAPS PharmSciTech. 2007;8(1):26

Authors: Faraj JA, Dorati R, Schoubben A, Worthen D, Selmin F, Capan Y, Leung K, DeLuca PP

The objective of this study was to characterize the stability of KSL-W, an antimicrobial decapeptide shown to inhibit the growth of oral bacterial strains associated with caries development and plaque formation, and its potential as an antiplaque agent in a chewing gum formulation. KSL-W formulations with or without the commercial antibacterial agent cetylpyridinium chloride (CPC) were prepared. The release of KSL-W from the gums was assessed in vitro using a chewing gum apparatus and in vivo by a chew-out method. A reverse-phase high-performance liquid chromatography method was developed for assaying KSL-W. Raw material stability and temperature and pH effects on the stability of KSL-W solutions and interactions of KSL-W with tooth-like material, hydroxyapatite discs, were investigated. KSL-W was most stable in acidic aqueous solutions and underwent rapid hydrolysis in base. It was stable to enzymatic degradation in human saliva for 1 hour but was degraded by pancreatic serine proteases. KSL-W readily adsorbed to hydroxyapatite, suggesting that it will also adsorb to the teeth when delivered to the oral cavity. The inclusion of CPC caused a large increase in the rate and extent of KSL-W released from the gums. The gum formulations displayed promising in vitro/in vivo release profiles, wherein as much as 90% of the KSL-W was released in a sustained manner within 30 minutes in vivo. These results suggest that KSL-W possesses the stability, adsorption, and release characteristics necessary for local delivery to the oral cavity in a chewing gum formulation, thereby serving as a novel antiplaque agent.

PMID: 17408225 [PubMed - indexed for MEDLINE]

Historical perspectives on the clinical development of bisphosphonates in the treatment of bone diseases.

J Musculoskelet Neuronal Interact. 2007 Jan-Mar;7(1):2-8

Authors: Francis MD, Valent DJ

Bisphosphonates (formerly termed diphosphonates) were first synthesized in the late 1800s; however, their clinical use has been relatively recent. The bisphosphonates' affinity for hydroxyapatite crystal surface led Procter and Gamble to test these compounds in dental, then medical applications. With key input from university researchers, this led to the medical use of the first bisphosphonate, etidronate disodium in 1968 to treat a young patient with myositis ossificans progressiva. Further clinical research led to widespread medical application for the bisphosphonate class including use as a diagnostic in radionuclide bone imaging agents, treatment of osteoporosis, Paget's disease of bone, hypercalcemia of malignancy and metastatic bone disease. The historical development of bisphosphonates provides an excellent example of how observations and knowledge obtained at the basic science level were applied and successfully tested in the clinic. The end result of these efforts has provided health care professionals with diagnostic and therapeutic tools to improve the lives of patients.

PMID: 17396000 [PubMed - indexed for MEDLINE]

Tyrosine sulfation of statherin.

Int J Biol Sci. 2007;3(4):237-41

Authors: Kasinathan C, Gandhi N, Ramaprasad P, Sundaram P, Ramasubbu N

Tyrosylprotein sulfotransferase (TPST), responsible for the sulfation of a variety of secretory and membrane proteins, has been identified and characterized in submandibular salivary glands (William et al. Arch Biochem Biophys 1997; 338: 90-96). In the present study we demonstrate the sulfation of a salivary secretory protein, statherin, by the tyrosylprotein sulfotransferase present in human saliva. Optimum statherin sulfation was observed at pH 6.5 and at 20 mm MnCl(2). Increase in the level of total sulfation was observed with increasing statherin concentration. The K(m)value of tyrosylprotein sulfotransferase for statherin was 40 microM. Analysis of the sulfated statherin product on SDS-polyacrylamide gel electrophoresis followed by autoradiography revealed (35)S-labelling of a 5 kDa statherin. Further analysis of the sulfated statherin revealed the sulfation on tyrosyl residue. This study is the first report demonstrating tyrosine sulfation of a salivary secretory protein. The implications of this sulfation of statherin in hydroxyapatite binding and Actinomyces viscosus interactions are discussed.

PMID: 17389930 [PubMed - indexed for MEDLINE]

A liver-derived immunosuppressive factor is an arginase: identification and mechanism of immunosuppression.

Biomed Res. 2007 Feb;28(1):17-23

Authors: Ohtani Y, Hiyoshi M, Ohkubo T, Tsuji K, Hagihara M, Nakasaki H, Makuuchi H, Nagata N, Mine T, Takada S, Yamamura M, Tsuda M

We found a substance in culture medium of neonatal pig liver fragments, which suppresses an immune response monitored by (3)H-thymidine incorporation using phytohemagglutinin (PHA)-stimulated lymphocytes. We named it as an immunosuppressive factor (ISF). To purify ISF, ammonium sulfate fractionation, DE52, SP-Sephadex, hydroxyapatite, blue Sepharose, heparin Sepharose and Superdex gel filtration columns were used. Using these purification procedures, ISF was purified 1,254-fold, with 9.2% recovery, from the culture medium of neonatal pig liver fragments, and was identified as arginase by its biochemical characteristics including molecular size, amino acid sequences of digested peptides and expression of arginase activity. The addition of ISF caused to decrease in arginine concentration in culture medium and at the same time DNA synthesis was suppressed dose-dependently, both of which were recovered by the addition of NOHA (N(G)-hydroxy-L-arginine), an arginase inhibitor. In addition, the depletion of arginine in culture medium also led to the inhibition of DNA synthesis. These results led us to the conclusion that immunosuppressive effect of ISF was due to arginase activity that decreased arginine concentration in culture medium, not to another function of ISF.

PMID: 17379953 [PubMed - indexed for MEDLINE]

Radiolanthanide complexes with tetraazamacrocycles bearing methylphosphonate pendant arms as bone seeking agents.

Q J Nucl Med Mol Imaging. 2007 Mar;51(1):6-15

Authors: Gano L, Marques F, Campello MP, Balbina M, Lacerda S, Santos I

AIM: Radiolanthanide complexes with ligands bearing phosphonate groups have demonstrated their usefulness as bone seeking agents. Herein, we report on the synthesis of 153Sm and 166Ho complexes with 12- to 14-membered macrocycles containing different number of methylphosphonate pendant arms and their in vitro and in vivo evaluation in order to assess the effect of the cavity size and type of appended arms on their biological behavior. METHODS: Radioactive macrocycle complexes were prepared by reaction of (153)Sm/(166)Ho nitrates with four different tetraazamacrocycles bearing methylphosphonate groups. Radiochemical behavior, in vitro stability and charge of complexes were studied by chromatography and electrophoresis. The lipophilicity, plasmatic protein binding and adsorption onto hydroxyapatite (HA) were evaluated by in vitro assays. Biodistribution was assessed in CD-1 mice. Radiolabeling efficiency depends both on radionuclide and ligand structure. All the complexes are hydrophilic with an overall negative charge and relatively low protein binding. High in vitro stability in human serum and adsorption onto HA was found for all the complexes. RESULTS: Biodistribution and in vivo stability studies have demonstrated promising biological profile for targeted radiotherapy, namely a rapid tissue clearance from most organs and rapid total excretion. Additionally, 166Ho-tritp has a high bone uptake, which led to high bone/ blood and bone/muscle ratios. CONCLUSIONS: Our results clearly demonstrate that 12- and 13-membered macrocyclic ligands led to stable complexes with biological profile adequate to radionuclide therapy. The favorable in vivo behavior highlights the interest to further investigate these or closely related complexes to be used as bone seeking agents.

PMID: 17372568 [PubMed - indexed for MEDLINE]

Purification and characterization of alcohol dehydrogenase reducing N-benzyl-3-pyrrolidinone from Geotrichum capitatum.

J Biosci Bioeng. 2007 Feb;103(2):174-8

Authors: Yamada-Onodera K, Fukui M, Tani Y

(S)-N-Benzyl-3-pyrrolidinol is widely used in the synthesis of pharmaceuticals as a chiral building block. We produced 30 mM (S)-N-benzyl-3-pyrrolidinol (enantiometric excess > 99.9%) from the corresponding ketone N-benzyl-3-pyrrolidinone with more than 99.9% yield in 28 h of the resting-cell reaction of Geotrichum capitatum JCM 3908. NAD(+)-dependent alcohol dehydrogenase reducing N-benzyl-3-pyrrolidinone from G. capitatum JCM 3908 was purified to homogeneity by ammonium sulfate fractionation and a series of DEAE-Toyopearl, Butyl-Toyopearl, Superdex 200, and Hydroxyapatite column chromatographies. The results of SDS-PAGE and HPLC showed the enzyme to be a dimer with a molecular mass of 78 kDa. The purified enzyme produced (S)-N-benzyl-3-pyrrolidinol (e.e.>99.9%) from N-benzyl-3-pyrrolidinone. The enzyme reduced 2,3-butanedione, 2-hexanone, cyclohexanone, propionaldehyde, n-butylaldehyde, n-hexylaldehyde, n-octylaldehyde, n-valeraldehyde, and benzylacetone more effectively than it did N-benzyl-3-pyrrolidinone. No activity was detected towards N-benzyl-2-pyrrolidinone or 2-pyrrolidinone. The activity towards (R)-N-benzyl-3-pyrrolidinol was not detected under the assay conditions employed. The oxidizing activity of the enzyme was higher towards 2-propanol, 2-butanol, 2-pentanol, 2-hexanol, 3-hexanol, and 1-phenyl-2-propanol than towards (S)-N-benzyl-3-pyrrolidinol. The K(m) values for N-benzyl-3-pyrrolidinone reduction and (S)-N-benzyl-3-pyrrolidinol oxidation were 0.13 and 8.47 mM, respectively. To our knowledge, this is the first time that an N-benzyl-3-pyrrolidinol/N-benzyl-3-pyrrolidinone oxidoreductase was purified from a eukaryote; moreover, this is the first report of (S)-N-benzyl-3-pyrrolidinol dehydrogenase activity in microorganisms. This enzyme showed features different from those of known prokaryotic N-benzyl-3-pyrrolidinone reductases. This enzyme will be very useful for the production of chiral compounds.

PMID: 17368401 [PubMed - indexed for MEDLINE]

Effects of trabecular calcium phosphate scaffolds on stress signaling in osteoblast precursor cells.

Biomaterials. 2007 Jun;28(17):2747-53

Authors: Appleford MR, Oh S, Cole JA, Carnes DL, Lee M, Bumgardner JD, Haggard WO, Ong JL

The objective of this research was to investigate stress-signaling patterns in response to two-dimensional (2-D) and three-dimensional (3-D) calcium phosphate (CP) materials using human embryonic palatal mesenchyme cells (HEPM, CRL-1486, ATCC, Manassas, VA), an osteoblast precursor cell line. Control discs and scaffolds were fabricated from hydroxyapatite and beta tri-CP ceramics. Phospho-specific antibody cell-based ELISA technique was utilized on members of the mitogen-activated protein kinase cascade including; the extracellular signal-regulated kinases (ERK1/2), p38, c-Jun N-terminal kinase (JNK), and the anti-apoptosis mediator protein kinase B (AKT). Quantification of these signals was evaluated during the early attachment phase of osteoblast precursor cells. In this study, it was observed that 3-D CP scaffolds significantly activated the stress mediators p38 and JNK but not ERK1/2. This signal trend was matched with an up-regulation in AKT, suggesting the ability of cells to manage high stress signals in response to 3-D CP architecture and that 3-D CP scaffolds are necessary for studies simulating a natural trabecular bone organization. The absence of these signals in 2-D CP surfaces indicated the importance of local architecture conditions on cell stress response. It was concluded from this study that osteoblast precursor cells cultured in 3-D CP scaffolds experience greater stress-signaling patterns when compared to 2-D CP surfaces.

PMID: 17350089 [PubMed - indexed for MEDLINE]

[Preparation and structural detection of antibacterial hydroxyapatite coating material on Ti implant]

Shanghai Kou Qiang Yi Xue. 2006 Oct;15(5):543-6

Authors: Zhu ZY, Zhang FQ, Zheng XB

PURPOSE: To investigate the method for preparing antibacterial hydroxyapatite coating material on Ti implant,and detect its surface feature, chemical composition and the crystal structure. METHODS: The antibacterial hydroxyapatite coating material which contained silver-zirconium phosphate antimicrobial was prepared on the Ti implant by using vacuum plasma spraying technology. Samples were divided into 4 groups according to weight percent of the antimicrobial: group A (0), group B (2%), group C (5%) and group D (10%). The surface feature of each sample was observed under scanning electric microscope. The chemical composition and the crystal structure was detected by electronic probe and X-ray diffraction method respectively. RESULTS: The surface feature of each sample showed globular granule with caky structure and air pore. The crystal structure of group A, B, C mainly showed characteristic absorption band of Ca10(OH)2(PO4)6 which degraded while antimicrobial content increased. Except Ca10(OH)2(PO4)6 and CaZr (PO4)2, Na6CaP2O09 also appeared in group D. Ag+ could not be detected by electronic probe in group A and B. The contents of Ag+ in group C and D were similar. CONCLUSION: The antibacterial hydroxyapatite coating material which contained silver can be prepared on the Ti implant by using vacuum plasma spraying technology. The appropriate weight percent of the antimicrobial was 5%.

PMID: 17348234 [PubMed - in process]

Reliability of linear distance measurement for dental implant length with standardized periapical radiographs.

Bull Tokyo Dent Coll. 2006 Aug;47(3):105-15

Authors: Wakoh M, Harada T, Otonari T, Otonari-Yamamoto M, Ohkubo M, Kousuge Y, Kobayashi N, Mizuta S, Kitagawa H, Sano T

The purpose of this study was to investigate the accuracy of distance measurements of implant length based on periapical radiographs compared with that of other modalities. We carried out an experimental trial to compare precision in distance measurement. Dental implant fixtures were buried in the canine and first molar regions. These were then subjected to periapical (PE) radiography, panoramic (PA) radiography, conventional (CV) and medical computed (CT) tomography. The length of the implant fixture on each film was measured by nine observers and degree of precision was statistically analyzed. The precision of both PE radiographs and CT tomograms was closest at the highest level. Standardized PE radiography, in particular, was superior to CT tomography in the first molar region. This suggests that standardized PE radiographs should be utilized as a reliable modality for longitudinal and linear distance measurement, depending on implant length at local implantation site.

PMID: 17344618 [PubMed - indexed for MEDLINE]

Analyse titanium surface irradiated with laser, with and without deposited of durapatite.

Acta Cir Bras. 2006;21 Suppl 4:57-62

Authors: Sisti KE, Garcia IR, Guastaldi AC, Antoniolli AC, de Rossi R, Brochado Neto Ade L

PURPOSE: The aim of this study was to analyse the surface of titanium implants using disc irradiated with lasers. METHODS: Titanium discs were irradiated with laser high insensitive (Nd-YAG), deposited durapatite and used thermal treatment. Sample received qualitative morphological analyse trough micrographics with many size in SEM (Scanning Electron Microscopy). RESULTS: Surface laser irradiation shows roughness and isomorphic characteristic. The durapatite amplified the titanium surface area by method biomimetic. CONCLUSION: The surface treatment presented more deposition of durapatite, roughness on the surface, better isomorphic characteristic and increase quantitative in titanium surface area, samples shows rugous, roughness and homogeneity there is not found in the implants available at the market.

PMID: 17293968 [PubMed - in process]

Streptococcus gordonii Hsa environmentally constrains competitive binding by Streptococcus sanguinis to saliva-coated hydroxyapatite.

J Bacteriol. 2007 Apr;189(8):3106-14

Authors: Nobbs AH, Zhang Y, Khammanivong A, Herzberg MC

Competition between pioneer colonizing bacteria may determine polymicrobial succession during dental plaque development, but the ecological constraints are poorly understood. For example, more Streptococcus sanguinis than Streptococcus gordonii organisms are consistently isolated from the same intraoral sites, yet S. gordonii fails to be excluded and survives as a species over time. To explain this observation, we hypothesized that S. gordonii could compete with S. sanguinis to adhere to saliva-coated hydroxyapatite (sHA), an in vitro model of the tooth surface. Both species bound similarly to sHA, yet 10- to 50-fold excess S. gordonii DL1 reduced binding of S. sanguinis SK36 by 85 to >95%. S. sanguinis, by contrast, did not significantly compete with S. gordonii to adhere. S. gordonii competed with S. sanguinis more effectively than other species of oral streptococci and depended upon the salivary film on HA. Next, putative S. gordonii adhesins were analyzed for contributions to interspecies competitive binding. Like wild-type S. gordonii, isogenic mutants with mutations in antigen I/II polypeptides (sspAB), amylase-binding proteins (abpAB), and Csh adhesins (cshAB) competed effectively against S. sanguinis. By contrast, an hsa-deficient mutant of S. gordonii showed significantly reduced binding and competitive capabilities, while these properties were restored in an hsa-complemented strain. Thus, Hsa confers a selective advantage to S. gordonii over S. sanguinis in competitive binding to sHA. Hsa expression may, therefore, serve as an environmental constraint against S. sanguinis, enabling S. gordonii to persist within the oral cavity, despite the greater natural prevalence of S. sanguinis in plaque and saliva.

PMID: 17277052 [PubMed - indexed for MEDLINE]

Continuous bone loss around a tapered uncemented femoral stem: a long-term evaluation with DEXA.

Acta Orthop. 2006 Dec;77(6):877-85

Authors: Bod&#xE9;n HS, Sköldenberg OG, Salemyr MO, Lundberg HJ, Adolphson PY

BACKGROUND: Periprosthetic bone loss is a well-documented phenomenon after uncemented total hip arthroplasty (THA); however, little is known about how bone mineral density (BMD) changes after 2 years. PATIENTS AND METHODS: 14 patients with hip arthrosis (group A) were operated with a proximally porous- and hydroxyapatite-coated stem and followed for 10 years with DEXA, radiographs and Harris hip score (HHS). Another group of 14 patients (group B) was evaluated at 6 and 14 years using the same prosthesis and protocol. RESULTS: No stem was revised and all stems were well-Fixed. At final follow-up, HHS was 97 points in group A after 10 years and 94 points in group B after 14 years. Bone mineral changes in group A were greatest in Gruen zones 1 and 7, where the losses were 31% and 26%, respectively, after 2 years on the operated side. The decrease in BMD continued after 2 years and in Gruen zone 7 it was faster than the rate of bone loss on the control side. In group B, the annual change in BMD on the operated side was not significantly different from the bone loss in group A. INTERPRETATION: Up to 14 years after implantation of a tapered uncemented stem, the BMD in the calcar region continues to decrease faster than would be expected from normal ageing.

PMID: 17260195 [PubMed - indexed for MEDLINE]

RNAi-associated ssRNA-specific ribonucleases in Tombusvirus P19 mutant-infected plants and evidence for a discrete siRNA-containing effector complex.

Proc Natl Acad Sci U S A. 2007 Jan 30;104(5):1714-9

Authors: Omarov RT, Ciomperlik JJ, Scholthof HB

Tomato bushy stunt virus (TBSV) and other tombusviruses encode a p19 protein (P19), which is a suppressor of RNAi. Wild-type TBSV or p19-defective mutants initially show a similar infection course in Nicotiana benthamiana, but the absence of an active P19 results in viral RNA degradation followed by recovery from infection. P19 homodimers sequester 21-nt virus-derived duplex siRNAs, and it is thought that this prevents the programming of an antiviral RNA-induced silencing complex to avoid viral RNA degradation. Here we report on chromatographic fractionation (gel filtration, ion exchange, and hydroxyapatite) of extracts from healthy or infected Nicotiana benthamiana plants in combination with in vitro assays for ribonuclease activity and detection of TBSV-derived siRNAs. Only extracts of plants infected with p19 mutants provided a source of sequence-nonspecific but ssRNA-targeted in vitro ribonuclease activity that coeluted with components of a wide molecular weight range. In addition, we isolated a discrete approximately 500-kDa protein complex that contained approximately 21-nt TBSV-derived siRNAs and that exhibited ribonuclease activity that was TBSV sequence-preferential, ssRNA-specific, divalent cation-dependent, and insensitive to a ribonuclease inhibitor. We believe that this study provides biochemical evidence for a virus-host system that infection in the absence of a fully active RNAi suppressor induces ssRNA-specific ribonuclease activity, including that conferred by a RNA-induced silencing complex, which is likely the cause for the recovery of plants from infection.

PMID: 17244709 [PubMed - indexed for MEDLINE]

In vitro inhibition of Streptococcus mutans biofilm formation on hydroxyapatite by subinhibitory concentrations of anthraquinones.

Antimicrob Agents Chemother. 2007 Apr;51(4):1541-4

Authors: Coenye T, Honraet K, Rigole P, Jimenez PN, Nelis HJ

We report that certain anthraquinones (AQs) reduce Streptococcus mutans biofilm formation on hydroxyapatite at concentrations below the MIC. Although AQs are known to generate reactive oxygen species, the latter do not underlie the observed effect. Our results suggest that AQs inhibit S. mutans biofilm formation by causing membrane perturbation.

PMID: 17220400 [PubMed - indexed for MEDLINE]

Mitochondria-dependent apoptosis induced by nanoscale hydroxyapatite in human gastric cancer SGC-7901 cells.

Biol Pharm Bull. 2007 Jan;30(1):128-32

Authors: Chen X, Deng C, Tang S, Zhang M

Nanoscale hydroxyapatite (nano-HAP) has been reported to exhibit anti-cancer effect on several human cancers, but the molecular mechanism of which remains unclear. The aim of this study was to explore the mechanisms by investigating the effects of nano-HAP on human gastric cancer SGC-7901 cells. Our results showed that nano-HAP significantly reduced cell viability, and induced apoptosis in SGC-7901 cells characterized by hypodiploid DNA contents, morphological changes and DNA fragmentation. The increase in apoptosis was accompanied with the increased expression of Bax, a pro-apoptotic protein, and decreased expression of Bcl-2, an anti-apoptotic protein, the decrease of mitochondrial membrane potential and the release of cytochrome c from mitochondria into cytosol. Furthermore, the activation of caspases-3, and -9, but not activation of caspases-8 was induced by nano-HAP. Z-VAD-fmk, a universal caspase inhibitor, dose-dependently inhibited nano-HAP-induced apoptosis. This study demonstrates that nano-HAP inhibits the proliferation of SGC-7901 cells by inducing apoptosis, and the apoptotic pathway of nano-HAP-induced apoptosis is mediated through the mitochondrial-dependent and caspase-dependent pathway.

PMID: 17202672 [PubMed - indexed for MEDLINE]

Biocompatability of hydroxyapatite composite as a local drug delivery system.

J Orthop Surg (Hong Kong). 2006 Dec;14(3):315-8

Authors: Krisanapiboon A, Buranapanitkit B, Oungbho K

PURPOSE. To investigate the biocompatibility of hydroxyapatite composite (hydroxyapatite, plaster of Paris, and chitosan) impregnated with gentamicin, fosfomycin, imipenem, or amphotericin B. METHODS. The interactions of the extract from each drug against osteoblast were tested using the methylthiotetrazole test. RESULTS. Extracts from all drugs showed good biocompatibility at concentrations varying from 10 microgram/ml to 1000 microgram/ml. Imipenem and amphotericin B at a concentration of 1000 microgram/ml had a significantly higher percentage of cell viability than the control group. No morphological change of osteoblast was observed in all drug tests at any concentrations. CONCLUSION. The hydroxyapatite composite had a good biocompatibility for carrying gentamicin, fosfomycin, imipenem, or amphotericin B.

PMID: 17200535 [PubMed - indexed for MEDLINE]

Calcium homeostasis: solving the solubility problem.

J Musculoskelet Neuronal Interact. 2006 Oct-Dec;6(4):402-7

Authors: Talmage RV, Talmage DW

This report summarizes the evidence that the control of the concentration of free calcium ions in body fluids is centered at mineralized bone surfaces. This process involves an increase in the solubility of bone mineral produced by the non-collagenous proteins existing in the bone extracellular fluid (ECF) and on the adjacent surfaces of bone. The result is a basic equilibrium level produced in the absence of parathyroid hormone (PTH), which is well above the solubility of bone mineral. The effect of PTH is to increase the solubility of bone mineral still further, but the mechanism by which the hormone acts is unknown. The lining cells of the bone contain receptors for PTH and can be observed to respond to this hormone, but the relationship between this response and the increased solubility of bone remains to be discovered. Further research in this field is strongly urged.

PMID: 17185838 [PubMed - indexed for MEDLINE]

[Assessment of bovine biomaterials containing bone morphogenetic proteins bound to absorbable hydroxyapatite in rabbit segmental bone defects]

Acta Cir Bras. 2006 Nov-Dec;21(6):366-73

Authors: Caporali EH, Rahal SC, Morceli J, Taga R, Granjeiro JM, Cestari TM, Mamprim MJ, Correa MA

PURPOSE: To evaluate the osteo-regenerative capacity of two proprietary bone grafting materials, using a segmental defect model in both radial diaphyses of rabbits. METHODS: The right defect was filled with pooled bone morphogenetic proteins (pBMPs) bound to absorbable ultrathin powdered hydroxyapatite (HA) mixed with inorganic and demineralized bone matrix and bone-derived collagen, derived from bovine bone (Group A). The left defect was filled with bovine demineralized bone matrix and pBMPs bound to absorbable ultrathin powdered HA (Group B). In both groups, an absorbable membrane of demineralized bovine cortical was used to retain the biomaterials in the bone defects, and to guide the tissue regeneration. The rabbits were euthanized 30, 90 and 150 days after surgery. Radiographic, tomographic and histologic evaluations were carried out on all specimens. RESULTS: At 30 days, the demineralized cortical bone cover was totally resorbed in both groups. HA was totally resorbed from Group A defects, whereas HA persisted in Group B defects. A prominent foreign body reaction was evident with both products, more pronounced in sections from Group B. At 90 days, the defects in Group B exhibited more new bone than Group A. However, at 150 days after surgery, neither treatment had stimulated complete repair of the defect. CONCLUSION: The partial bone healing of the segmental defect occurred with low or none performance of the biomaterials tested.

PMID: 17160247 [PubMed - indexed for MEDLINE]

Development of a novel 99mTc-chelate-conjugated bisphosphonate with high affinity for bone as a bone scintigraphic agent.

J Nucl Med. 2006 Dec;47(12):2042-7

Authors: Ogawa K, Mukai T, Inoue Y, Ono M, Saji H

In bone scintigraphy using (99m)Tc with methylenediphosphonate ((99m)Tc-MDP) and hydroxymethylenediphosphonate ((99m)Tc-HMDP), it takes 2-6 h after an injection before imaging can start. This interval could be shortened with a new radiopharmaceutical with higher affinity for bone. Here, based on the concept of bifunctional radiopharmaceuticals, we designed a (99m)Tc-mercaptoacetylglycylglycylglycine (MAG3)-conjugated hydroxy-bisphosphonate (HBP) ((99m)Tc-MAG3-HBP) and a (99m)Tc-6-hydrazinopyridine-3-carboxylic acid (HYNIC)-conjugated hydroxy-bisphosphonate ((99m)Tc-HYNIC-HBP). METHODS: (99m)Tc-MAG3-HBP was prepared by complexation of MAG3-HBP with (99m)Tc using SnCl(2) as a reductant. The precursor of (99m)Tc-HYNIC-HBP, HYNIC-HBP, was obtained by deprotection of the Boc group after the coupling of Boc-HYNIC to a bisphosphonate derivative. (99m)Tc-HYNIC-HBP was prepared by a 1-pot reaction of HYNIC-HBP with (99m)TcO(4)(-), tricine, and 3-acetylpyridine in the presence of SnCl(2). Affinity for bone was evaluated in vitro by hydroxyapatite-binding assays for (99m)Tc-HMDP, (99m)Tc-MAG3-HBP, and (99m)Tc-HYNIC-HBP. Biodistribution experiments for the 3 (99m)Tc-labeled compounds were performed on normal rats. RESULTS: (99m)Tc-MAG3-HBP and (99m)Tc-HYNIC-HBP were each prepared with a radiochemical purity of >95%. In the in vitro binding assay, (99m)Tc-MAG3-HBP and (99m)Tc-HYNIC-HBP had greater affinity for hydroxyapatite than (99m)Tc-HMDP. In the biodistribution experiments, (99m)Tc-MAG3-HBP and (99m)Tc-HYNIC-HBP had higher levels of radioactivity in bone than (99m)Tc-HMDP. (99m)Tc-MAG3-HBP was cleared from the blood slower than (99m)Tc-HMDP, whereas there was no significant difference in clearance between (99m)Tc-HYNIC-HBP and (99m)Tc-HMDP. Consequently, (99m)Tc-HYNIC-HBP showed a higher bone-to-blood ratio than (99m)Tc-HMDP. CONCLUSION: We developed a novel (99m)Tc-chelate-conjugated bisphosphonate with high affinity for bone and rapid clearance from blood, based on the concept of bifunctional radiopharmaceuticals. The present findings indicate that (99m)Tc-HYNIC-HBP holds great potential for bone scintigraphy.

PMID: 17138748 [PubMed - indexed for MEDLINE]

Calcium modulates interactions between bacteria and hydroxyapatite.

J Dent Res. 2006 Dec;85(12):1124-8

Authors: Venegas SC, Palacios JM, Apella MC, Morando PJ, Blesa MA

Bacterial adhesion onto hydroxyapatite is known to depend on the surface properties of both the biomaterial and the bacterial strain, but less is known about the influence of the composition of the aqueous medium. Here, the adhesion of Streptococcus mutans and 3 different Lactobacilli on powdered hydroxyapatite was shown to change with Ca2+ concentration. The effect depends on the surface properties of each strain. Adhesion of Lactobacillus fermentum and salivarius (and of Streptococcus mutans at low Ca2+) was enhanced with increasing Ca2+ concentration. Lactobacillus casei was efficiently removed by adhesion on hydroxyapatite, even without Ca2+ addition, and the effect of this ion was only marginal. The results are interpreted in terms of Ca2+-mediated adhesion, and relative to the hydrophobic properties of each strain and the electrical properties of the bacterial and solid surfaces (electrophoretic mobility).

PMID: 17122166 [PubMed - indexed for MEDLINE]

Evaluation of hydroxyapatite cement for frontal sinus obliteration after mucocele resection.

Arch Facial Plast Surg. 2006 Nov-Dec;8(6):416-22

Authors: Taghizadeh F, Kr&#xF6;mer A, Laedrach K

OBJECTIVES: To retrospectively evaluate our experience with frontal sinus obliteration using hydroxyapatite cement (BoneSource; Stryker Biotech Europe, Montreux, Switzerland) and compare it with fat obliteration over the approximate same period. Frontal sinus obliteration with hydroxyapatite cement represents a new technique for obliteration of the frontal sinus after mucocele resection. METHODS: Exploration of the frontal sinus was performed using bicoronal, osteoplastic flaps, with mucosal removal and duct obliteration with tissue glue and muscle or fascia. Flaps were elevated over the periorbita, and Silastic sheeting was used to protect the BoneSource material from exposure as it dried. The frontal table was replaced when appropriate. RESULTS: Sixteen patients underwent frontal sinus obliteration with fat (fat obliteration group), and 38 patients underwent obliteration with BoneSource (BoneSource group). Fat obliteration failed in 2 patients, who underwent subsequent BoneSource obliteration, and none of the patients in the BoneSource group has required removal of material because of recurrent complications. Frontobasal trauma (26 patients [68%] in the BoneSource group and 9 patients [56%] in the fat obliteration group) was the most common history of mucocele formation in both groups. Major complications in the BoneSource group included 1 patient with skin fistula, which was managed conservatively, and 1 patient with recurrent ethmoiditis, which was managed surgically. Both complications were not directly attributed to the use of BoneSource. Contour deficit of the frontal bone occurred in 1 patient in the fat obliteration group and in none in the BoneSource group. Two patients in the fat obliteration group had donor site complications (hematoma and infection). Thirteen patients in the BoneSource group had at least 1 prior attempt at mucocele drainage, and no statistical relation existed between recurrent surgery and preservation of the anterior table. CONCLUSION: Hydroxyapatite is a safe, effective material to obliterate frontal sinuses infected with mucoceles, with minimal morbidity and excellent postoperative contour.

PMID: 17116791 [PubMed - indexed for MEDLINE]

Escherichia coli HdeB is an acid stress chaperone.

J Bacteriol. 2007 Jan;189(2):603-10

Authors: Kern R, Malki A, Abdallah J, Tagourti J, Richarme G

We cloned, expressed, and purified the hdeB gene product, which belongs to the hdeAB acid stress operon. We extracted HdeB from bacteria by the osmotic-shock procedure and purified it to homogeneity by ion-exchange chromatography and hydroxyapatite chromatography. Its identity was confirmed by mass spectrometry analysis. HdeB has a molecular mass of 10 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which matches its expected molecular mass. We purified the acid stress chaperone HdeA in parallel in order to compare the two chaperones. The hdeA and hdeB mutants both display reduced viability upon acid stress, and only the HdeA/HdeB expression plasmid can restore their viability to close to the wild-type level, suggesting that both proteins are required for optimal protection of the bacterial periplasm against acid stress. Periplasmic extracts from both mutants aggregate at acidic pH, suggesting that HdeA and HdeB are required for protein solubilization. At pH 2, the aggregation of periplasmic extracts is prevented by the addition of HdeA, as previously reported, but is only slightly reduced by HdeB. At pH 3, however, HdeB is more efficient than HdeA in preventing periplasmic-protein aggregation. The solubilization of several model substrate proteins at acidic pH supports the hypothesis that, in vitro, HdeA plays a major role in protein solubilization at pH 2 and that both proteins are involved in protein solubilization at pH 3. Like HdeA, HdeB exposes hydrophobic surfaces at acidic pH, in accordance with the appearance of its chaperone properties at acidic pH. HdeB, like HdeA, dissociates from dimers at neutral pH into monomers at acidic pHs, but its dissociation is complete at pH 3 whereas that of HdeA is complete at a more acidic pH. Thus, we can conclude that Escherichia coli possesses two acid stress chaperones that prevent periplasmic-protein aggregation at acidic pH.

PMID: 17085547 [PubMed - indexed for MEDLINE]

Cytocidal effects of atheromatous plaque components: the death zone revisited.

FASEB J. 2006 Nov;20(13):2281-90

Authors: Li W, Ostblom M, Xu LH, Hellsten A, Leanderson P, Liedberg B, Brunk UT, Eaton JW, Yuan XM

OBJECTIVE: Earlier we suggested that atheroma lesions constitute a "death zone" containing toxic materials that may cause dysfunction and demise of invading macrophages to prevent the removal of plaque materials. Here we have assessed the cytotoxic effects of nonfractionated gruel and insoluble (ceroid-like) material derived from advanced human atheroma. METHODS AND RESULTS: The insoluble material within advanced atherosclerotic plaque was isolated following protease K digestion and extensive extraction with aqueous and organic solvents. FTIR, Raman, and atomic absorption spectroscopy suggested that, despite its fluorescent nature, this material closely resembled hydroxyapatite and dentin, but also contained a significant amount of iron and calcium. When added to J774 cells and human macrophages in culture, this insoluble substance was phagocytosed, and progressive cell death followed. However, an even more cytotoxic activity was found in the atheromatous "gruel" that contains abundant carbonyls/aldehydes. Cell death caused by both crude gruel and ceroid could be blocked by preincubating cells with the lipophilic iron chelator salicylaldehyde isonicotinoyl hydrazone, apoferritin, BAPTA/AM, or sodium borohydride, indicating that cellular iron, calcium, and reactive aldehyde(s) are responsible for the observed cytotoxicity. CONCLUSIONS: Toxic materials within atheromatous lesions include both ceroid and even more cytotoxic lipidaceous materials. The cytotoxic effects of these plaque components may help explain the persistence of atherosclerotic lesions.

PMID: 17077305 [PubMed - indexed for MEDLINE]

Bone remodeling around the Cambridge cup: a DEXA study of 50 hips over 2 years.

Acta Orthop. 2006 Oct;77(5):726-32

Authors: Field RE, Cronin MD, Singh PJ, Burtenshaw C, Rushton N

BACKGROUND: In a prospective 2-year study we have used dual-energy X-ray absorptiometry to measure periprosthetic bone mineral density (BMD) following implantation of a novel, "physiological", acetabular component designed using composite materials. METHOD: The acetabular components were implanted in hydroxyapatite (HA) and HA-removed options. They were implanted in conjunction with a cemented femoral component in 50 female patients who presented with displaced, subcapital, fractures of the neck of the femur. Regions of interest (ROI) were defined according to De Lee and Charnley. BMD during follow-up was compared with immediate postoperative values for the affected limb. RESULTS: The mean precision error (CV%) was 1.01%, 2.26% and 1.12%, for ROI I, II and III respectively. The mean change in BMD, for both cups, was analyzed. There was no significant difference between the BMD changes induced with the HA- and non-HA-coated cups. INTERPRETATION: After an initial fall in BMD in all 3 ROI at 6 months, ROI I and ROI II showed return to baseline BMD by 2 years. ROI III showed no significant decrease in BMD beyond 6 months, but did not return to baseline levels. Statistical analysis revealed no significant decrease in BMD in ROI I and ROI II at 2 years, compared with immediate postoperative values. The changes in BMD reflect a pattern of maximally reduced stress in the non-weight-bearing zone (ROI III), with preservation of bone density in weight bearing zones ROI I and ROI II. These results support the design principles of the Cambridge cup.

PMID: 17068702 [PubMed - indexed for MEDLINE]

Folding of the C-terminal bacterial binding domain in statherin upon adsorption onto hydroxyapatite crystals.

Proc Natl Acad Sci U S A. 2006 Oct 31;103(44):16083-8

Authors: Goobes G, Goobes R, Schueler-Furman O, Baker D, Stayton PS, Drobny GP

Statherin is an enamel pellicle protein that inhibits hydroxyapatite (HAP) nucleation and growth, lubricates the enamel surface, and is recognized by oral bacteria in periodontal diseases. We report here from solid-state NMR measurements that the protein's C-terminal region folds into an alpha-helix upon adsorption to HAP crystals. This region contains the binding sites for bacterial fimbriae that mediate bacterial cell adhesion to the surface of the tooth. The helical segment is shown through long-range distance measurements to fold back onto the intermediate region (residues Y16-P28) defining the global fold of the protein. Statherin, previously shown to be unstructured in solution, undergoes conformation selection on its substrate mineral surface. This surface-induced folding of statherin can be related to its functionality in inhibiting HAP crystal growth and can explain how oral pathogens selectively recognize HAP-bound statherin.

PMID: 17060618 [PubMed - indexed for MEDLINE]