Comparative studies of intra- and extramitochondrial calcium phosphates from the hepatopancreas of the blue crab (Callinectes sapidus)

Subcellular fractions of cytoplasmic mineral granules and mineral-loaded mitochondria were isolated from whole homogenates of hepatopancreas of the blue crab (Callinectes sapidus). Chemical, physical, and morphologic studies were carried out on both subcellular fractions, with and without prior removal of organic components by hydrazine extraction. In contrast to cytoplasmic granules, whole mitochondria contained appreciable amounts of mineral ions not associated with a solid mineral phase. Quantitative analyses and infrared spectroscopy showed cytoplasmic and mitochondrial mineral phases to be calcium phosphates of similar but not identical composition. Both cytoplasmic and mitochondrial mineral phases, as in synthetic amorphous calcium phosphate, show noncrystalline patterns when examined by infrared spectroscopy and x-ray diffraction, and a common ultrastructure of clustered spheres of approximately 100 Å diameter. The findings suggest that amorphous calcium phosphate in biological systems may exhibit appreciable variation in Ca/P and in the content of foreign ions such as Mg²⁺, ADP, and ATP. A mitochondriogenic mechanism of calcification could not be confirmed nor refuted by this study.     

Stabilization of amorphous calcium phosphate by Mg and ATP

Summary A synergistic effect has been demonstrated when magnesium and adenosine triphosphate (ATP) are used together in solution to delay the conversion of a slurry of amorphous calcium phosphate (ACP) to crystalline hydroxyapatite (HA). Conversion is delayed in some instances more than 10 times as long as with either ATP or Mg alone. In all experiments conversion did not begin until ATP in solution had decreased through hydrolysis to an undetectable level. The effect of Mg is to decrease substantially the rate at which ATP hydrolysis occurs. Once conversion began it proceeded more slowly in the presence of both Mg and ATP than with Mg or ATP alone. ATP was also found to prevent the formation of HA from metastable solutions of calcium and phosphate which did not contain any solid phase. Over the time period of these experiments, ATP hydrolyzed to a negligible extent in Tris-HCl buffer and in solutions containing Ca, PO₄, and Ca plus PO₄ ions. Hydrolysis of ATP does occur in the presence of ACP or HA, presumably by transphosphorylation on the surface of the solid calcium phosphate phase. It was concluded that ATP stabilized ACP, not by affecting its dissolution, but either by poisoning heteronuclear growth sites, or by poisoning the growth of embryonic HA nuclei (formed heterogeneously or homogeneously) before their critical size is reached, or by poisoning both. In the case of embryonic HA nuclei, the poisoned nuclei would go back into solution preventing HA crystal formation. In addition, it was found that the neutral Ca₉(PO₄)₆ clusters, which are believed to be the basic structural unit of ACP, break down into individual Ca and PO₄ ions when ACP dissolves in aqueous medium.     

In vitro precipitation of calcium phosphate under intracellular conditions: formation of brushite from an amorphous precursor in the absence of ATP

Summary Release of mitochondrial calcium has been shown to occur concomitant with mineral ion loading of matrix vesicles at the onset of mineralization in epiphyseal growth plate cartilage. Matrix vesicles contain amorphous calcium phosphate (ACP), a mineral form that usually results from rapid precipitation at high initial levels of Ca²⁺ and/or inorganic P (Pi). Since the cytosol of growth plate chondrocytes has been found to contain high levels of Pi, rapid release of mitochondrial Ca²⁺ into the cytosol may causelocal precipitation of calcium phosphate and thus be coupled with matrix vesicle formation. Studies were carried out to determine the kinetics and nature of mineral formation that occur when small amounts of Ca²⁺ are added under various conditions to a Pi buffer composed of electrolytes matched in concentrations and pH to that of the cytosol of epiphyseal chondrocytes. Depending on the manner in which Ca²⁺ was added, ACP, dicalcium phosphate dihyrate (DCPD), or apatite (HA) first formed. In the presence of ATP, ACP was the only solid phase detected, being stable for at least 24 h. However, in its absence, ACP rapidly transformed into DCPD, Increasing the pH of the reaction buffer from 6.9 to 7.5 increased the amount of ACP initially formed, but DCPD was consistently found upon ACP transformation. Yet at pH 8.0, ACP persisted for at least 24 h. The amount of precipitate formed was proportional to the level of added Ca²⁺; precipitates formed when as little as 1.0 mmole was added per liter of buffer. Our findings support thepossibility that rapid release of mitochondrial Ca²⁺ may cause localized intracellular precipitation of ACP. Since nascent ACP is known to stimulate membrane fusion and blebbing of vesicles, these findings may explain the presence of ACP in matrix vesicles. The rapid conversion of ACP to DCPD in the absence of ATP under these conditions may also explain the reported occurrence of DCPD in samples of early mineralizing tissue.     

Effect of oral calcium carbonate on aortic calcification in apolipoprotein E-deficient (apoE-/-) mice with chronic renal failure.

BACKGROUND: In chronic kidney disease (CKD) patients, the intake of calcium-based phosphate binders is associated with a marked progression of coronary artery and aortic calcification, in contrast to patients receiving calcium-free phosphate binders. The aim of this study was to reexamine the role of calcium carbonate in vascular calcification and to analyse its effect on aortic calcification-related gene expression in chronic renal failure (CRF). METHODS: Mice deficient in apolipoprotein E underwent either sham operation or subtotal nephrectomy to create CRF. They were then randomly assigned to one of the three following groups: a control non-CRF group and a CRF group fed on standard diet, and a CRF group fed on calcium carbonate enriched diet, for a period of 8 weeks. Aortic atherosclerotic plaque and calcification were evaluated using quantitative morphologic image processing. Aortic gene and protein expression was examined using immunohistochemistry and Q-PCR methods. RESULTS: Calcium carbonate supplementation was effective in decreasing serum phosphorus but was associated with a higher serum calcium concentration. Compared with standard diet, calcium carbonate enriched diet unexpectedly induced a significant decrease of both plaque (p<0.05) and non-plaque-associated calcification surface (p<0.05) in CRF mice. It also increased osteopontin (OPN) protein expression in atherosclerotic lesion areas of aortic root. There was also a numerical increase in OPN and osteoprotegerin gene expression in total thoracic aorta but the difference did not reach the level of significance. Finally, calcium carbonate did not change the severity of atherosclerotic lesions. CONCLUSION: In this experimental model of CRF, calcium carbonate supplementation did not accelerate but instead decreased vascular calcification. If our observation can be extrapolated to humans, it appears to question the contention that calcium carbonate supplementation, at least when given in moderate amounts, necessarily enhances vascular calcification. It is also compatible with the hypothesis of a preponderant role of phosphorus over that of calcium in promoting vascular calcification in CRF.     

Complementary Information on In Vitro Conversion of Amorphous (Precursor) Calcium Phosphate to Hydroxyapatite from Raman Microspectroscopy and Wide-Angle X-Ray Scattering

In addition to mechanical functions, bones have an essential role in metabolic activity as mineral reservoirs that are able to absorb and release ions. Bioapatite, considered the major component in the mineralized part of mammalian bones, is a calcium phosphate mineral with a structure that closely resembles hydroxyapatite (HA, Ca₁₀[PO₄]₆[OH]₂) with variable chemical substitutions. It is important to note that it continues to be chemically active long after it has been initially deposited. Detailed understanding of changes in the mineral phase as HA matures is essential for understanding how normal bone achieves its remarkable mechanical performance, how it is altered in disease, as well as the effects of therapeutic interventions. A model system for investigation of the in vivo maturation of HA is available, namely, the in vitro conversion of amorphous calcium phosphate (ACP) to HA in a supersaturated solution of calcium and phosphate ions. In the present study, this system was employed to correlate with the changes in chemistry and poorly crystalline HAP crystal size, shape, and habit. The results of the X-ray diffraction as well as Raman analyses showed that as the crystallites mature in the 002 and 310 directions both the full width at half-height and wavelength at maximum of the Raman peaks change as a function of reaction extent and crystallite maturation, size, and shape. Moreover, such analyses can be performed in intact bone specimens through Raman microspectroscopic and imaging analyses with a spatial resolution of 0.6–1 μ, by far superior to the one offered by other microspectroscopic techniques, thus potentially yielding important new information on the organization and mineral quality of normal and fragile bone.     

Inhibition of the amorphous calcium phosphate phase transformation reaction by polyphosphates and metal ions

Summary The induction time for amorphous calcium phosphate (ACP) phase transformation was monitored at pH 7.4 and T=25°C with [Ca²⁺]₀=[PO₄]₀=4.0×10⁻³ M, as a function of added crystal growth inhibitors Mg²⁺, Sr²⁺, Zn²⁺, pyrophosphate (PP), and tripolyphosphate (TPP). Metal ions increase the induction time for the initiation of the phase change reaction in the order Zn²⁺<Sr²⁺<Mg²⁺. For polyphosphates it was observed that both PP and TPP are potent inhibitors with TPP more effective than PP as expected. The combination of Mg²⁺ or Sr²⁺ and PP or TPP leads to a synergistic delay in the onset of the phase conversion. The greatest inhibition was observed for Mg²⁺ and TPP. Reaction solutions containing 2.0×10⁻⁴ M Mg²⁺ and 4.0×10⁻⁵ M TPP resulted in a 90% increase in the induction time over what would be anticipated from an additive effect from these species.     

An X-ray crystallographic examination of calcium phosphate formation in Ca(OH)2/H3PO4 mixtures

Precipitates formed over a 10 day period by adding variable amounts of Ca(OH)₂ to H₃PO₄ were examined chemically and by X-ray diffraction in order to determine and to relate the crystallographic changes observed during calcium phosphate formation in this system to those seen previously in dental plaque. In the lower Ca(OH)₂/H₃PO₄ ratio mixtures the initial precipitates were amorphous or poorly crystalline. The latter deposits showed an apatite-like diffraction pattern which changed to brushite and decreased in Ca/P ratio from approximately 1.2–1.0. Since the amorphous precipitates showed a similar decrease in the Ca/P ratio and a transient appearance of apatite, it was suggested that these initial precipitates, like the poorly crystalline deposits, may contain brushite amorphous to X-rays. Precipitates from the higher Ca(OH)₂/H₃PO₄ ratio mixtures changed from a poorly crystalline to a more crystalline apatite and the Ca/P ratio remained fairly constant. The relation between the pH, Ca and P on the one hand and the brushite and apatite contents and the pattern of crystallization of the precipitates on the other was strikingly similar to the same relationship observed earlier in dental plaque in situ, suggesting that the system used in this study could be used to study certain aspects of plaque mineralization in vitro.     

High-normal calcium (1.35 mmol/I) dialysate in patients on CAPD: efficient and safe long-term control of plasma calcium, phosphate, and parathyroid hormone

AIM.: The aim of the present study was to examine the long-term efficacyand safety of treatment with a high-normal calcium dialysatewith a calcium concentration of 1.35 mmol/l in patients on CAPD.This dialysate calcium concentration is close to the high-normalplasma ionized calcium level aimed at in dialysis patients inorder to suppress the parathyroid hormone secretion. The end-pointsof the study were (1) plasma ionized calcium (iCa) and phosphate(P) levels, (2) plasma intact parathyroid hormone (PTH) levels,(3) doses of calcium carbonate and alfacalcidol, (4) requirementsof Al-containing phosphate binders, and (5) bone mineral density(BMD). RESULTS.: Thirty-seven non-selected patients on CAPD treatment were followedfor an average of 10 months after switching from a dialysateCa of 1.75 to 1.35 mmol/l. After 1 week, a significant decreaseof mean iCa from 1.26±0.01 to 1.23±0.01 mmol/l(P<0.05) and an increase of median PTH from 80 to 135 pg/ml(P<0.01) were seen. From the 2nd week and onwards, however,basal levels of iCa and PTH were restored and remained stable.Mean plasma iCa was kept within 1.23–1.31 mmol/l; meanplasma P below 1.65 mmol/l and median PTH within 52–135pg/ml. Episodes of hypercalcaemia were few (1.2 cases of plasmaiCa>1.45 mmol/l per 100 treatment weeks), and the need forAl-containing P binders low with only five patients requringthis treatment for isolated and four patients for repeated episodesof hyperphosphataemia or hypercalcaemia. After switching froma dialysate Ca of 1.75 to 1.35 mmol/l, the doses of calciumcarbonate and alfacalcidol could be significantly increased.Furthermore, using the dialysate Ca of 1.35 mmol/l made it possibleto induce a controlled increase of PTH levels to 80–100pg/ml by a temporarily discontinuation of alfacalcidol and/ora reduction of calcium carbonate dosage in the patients wherePTH had become suppressed to levels below the upper normal limit.The intention of the treatment was to maintain PTH levels within1.5–2.5 times the upper normal limit for non-uraemic patients.Pre-study BMD of the vertebral bodies L2–L4 and of thefemoral neck were normal and not significantly different frompost-study measurements. CONCLUSIONS.: The present study demonstrated that when using a high-normaldialysate Ca concentration of 1.35 mmol/l in non-selected patientson CAPD treatment, high-normal plasma iCa and near-normal plasmaP levels could be readily achieved with a minimal risk of incidentalhypercalcaemia despite use of calcium carbonate as the mainP binder. As a consequnce of the tight Ca and P regulation,minimal doses of alfacalcidol were required to keep PTH withinacceptable limits. We recommend this dialysate Ca concentrationas a first-choice therapy for the majority of patients startingon CAPD treatment.     

手部A族链球菌感染致中毒性休克综合征的临床特点和治疗

目的报告手部A族链球菌(group A streptococcus,GAS)感染导致的中毒性休克综合征(toxic shock syndrome,TSS)的临床特点和治疗方法。方法对2004年1月-2005年9月收治的6例急性手部GAS感染导致的TSS患者,进行综合治疗。结果综合治疗2周后,4例患者完全治愈,伤口全部愈合,手功能恢复好。2例患者遗留轻度的手指关节僵硬,总TAM减少40°～60°,心、肝脏器轻度损害。3～6个月后随访,其中1例上述症状已完全愈合,手功能恢复好；另1例总TAM减少20°。结论GAS的生物学特性决定了TSS的临床特点和致病机理,应针对其生物学特性予以积极治疗。     

局部修复和(或)异体肌腱重建治疗急性膝关节后外侧复合结构损伤

 目的 探讨采用局部修复和（或）异体肌腱重建治疗急性膝关节后外侧复合结构（postero-lateral complex,PLC）损伤的方法及疗效。方法 2006年5月至2008年10月,收治急性P LC损伤患者12例,男9例,女3例;年龄23～47岁,平均31岁;合并后十字韧带损伤9例,合并前、后十字韧带同时损伤3例。首先在关节镜下采用异体肌腱解剖重建前、后十字韧带,然后对于P LC两端附着点撕脱损伤的患者采用铆钉固定、缝线缝合修复治疗;对于P LC实质部断裂的患者采用局部缝合修复和（或）异体肌腱重建的方法治疗。术后根据K T-1000、IKDC及Lysholm功能评定标准评价膝关节功能恢复情况。结果12例患者均获得随访,随访时间12～18个月,平均13.3个月。膝关节活动度由术前118.00°±6.77°提高至术后130.75°±3.05°。KT-1000由术前（14.85±1.83）mm改善至术后（4.18±1.88）mm。根据IKDC综合评定标准,A级7例,B级3例,C级1例,D级1例。Lysholm膝关节功能评分由术前35～44分[平均（38.83±3.16）分]提高至术后79～91分[平均（84.92±3.73）分]。所有患者患膝均无感染及免疫排斥反应。3例患者住院期间B超显示患侧小腿肌间静脉血栓,经低分子肝素钙治疗后好转。2例患者膝关节屈曲较对侧少15°。结论对于急性P LC损伤患者,PLC两端附着点撕脱损伤采用铆钉固定、缝线缝合修复;实质部断裂的患者采用局部缝合修复和（或）异体肌腱重建治疗可取得较好的效果。     

离体牙短期应用酪蛋白磷酸多肽钙磷复合体再矿化的实验研究

目的:评价短期应用10%酪蛋白磷酸多肽钙磷复合体(complex of casein phosphopeptide and amorphous calcium phosphate,CPP-ACP)(商品名:Tooth Mousse护牙素)离体牙釉质片再矿化的功效。方法:将正畸需要拔出的离体前磨牙15颗从冠根向一分为二,共30个实验样本,用自凝材料包埋于塑料圈内,根据扫描电镜样品的要求打磨抛光,抛光后的牙釉质面积为3mm×3mm。用数字随机表的方法随机分成4个实验组和1个对照组,每组6个。对照组是用37.5%磷酸酸蚀浸泡牙釉质2 min后不用护牙素浸泡,实验组均用37.5%磷酸酸蚀浸泡牙釉质2min后分别用Tooth Mousse护牙素涂搽牙面30 min,置于蒸馏水中浸泡。每组浸泡的时间逐步累加,A、B、C、D实验组分别浸泡时间为1、5、10、20h。每组待第2天在同一时间涂搽护牙素及在蒸馏水中浸泡的步骤同第1天,每天更换蒸馏水一次。每组连续作用5次。扫描电镜观察及用能谱检测钙的质量分数,统计分析各组釉柱再矿化与浸泡时间的关系。结果:A、B、C、D实验组釉质表面钙质量分数是(67.38±0.89、67.63±0.56、67.71±0.52、69.11±0.27)和酸蚀组65.74±0.74之间的差异有统计学意义(F=21.568,P=0.0000.01);用(Student-Newman-Keuls)法做多组间样本均数的两两统计比较分析,A、B、C组间差异均无统计学意义(P0.05);D实验组与A、B、C组间差异均有统计学意义(P0.05)。结论:Tooth Mousse护牙素体外实验在蒸馏水环境中多次短时间每天20h浸泡离体牙釉质在减少脱矿和促进再矿化方面较实验其余3组作用显著。     

Increased expression of monocyte chemoattractant protein-1 (MCP-1) by renal epithelial cells in culture on exposure to calcium oxalate, phosphate and uric acid crystals.

BACKGROUND: During the development of non-infectious kidney stones, crystals form and deposit in the kidneys and become surrounded by monocytes/macrophages (M/M). We have proposed that in response to crystal exposure renal epithelial cells produce chemokines, which attract the M/M to the sites of crystal deposition. We investigated the expression of monocyte chemoattractant protein-1 (MCP-1) mRNA and protein by NRK52E rat renal tubular epithelial cells exposed to calcium oxalate (CaOx), brushite (Br, a calcium phosphate) and uric acid (UA) crystals. METHODS: Confluent cultures of NRK52E cells were exposed to CaOx, Br or UA at a concentration of 250 micro g/ml (66.7 micro g/cm(2)). They were exposed for 1, 3, 6, 12, 24 and 48 h for isolation of mRNA and 24 h for ELISA to determine the secretion of protein into the culture medium. Since cells are known to produce free radicals on exposure to CaOx crystals we also investigated the effect of free radical scavenger catalase on the crystal induced expression of MCP-1 mRNA and protein. RESULTS: Exposure of NRK52E cells to the crystals resulted in increased expression of MCP-1 mRNA and production of the chemoattractant. CaOx crystals were most provocative while UA the least. Treatment with catalase had a negative effect on the increased expression of both MCP-1 mRNA and protein, which indicates the involvement of free radicals in up-regulation of MCP-1 production. CONCLUSION: Exposure to both CaOx and calcium phosphate crystals stimulates increased production of MCP-1. Free radicals appear to be involved in this up-regulation. Results indicate that MCP-1, which is often associated with localized inflammation, may be one of the chemokine mediators associated with the deposition of various urinary crystals in the kidneys during kidney stone formation. Because of the small number of experiments performed here, results must be confirmed by more extensive studies with larger sample size.     

蛇床子素和纳米氧化锆强韧化磷酸钙支架对成骨细胞增殖影响的研究

目的研究蛇床子素与纳米氧化锆强韧化磷酸钙骨支架的相容性，以及其在体外对幼兔成骨细胞增殖和成骨作用的影响。方法酶消化法分离培养幼兔股骨成骨细胞，噻唑兰法(MTT)测量成骨细胞增殖率，用碱性磷酸酶试剂盒测定细胞内骨碱性磷酸酶(ALP)活性。结果蛇床子素对大鼠新生成骨细胞的增殖和ALP活性具有显著的促进作用，与纳米氧化锆强韧化磷酸钙人工骨支架生物相容性良好。结论纳米氧化锆强韧化磷酸钙人工骨支架复合蛇床子素刺激的成骨细胞，是一种性能良好的复合骨组织工程材料。     

The entrapment of corrosion products from CoCr implant alloys in the deposits of calcium phosphate: a comparison of serum, synovial fluid, albumin, EDTA, and water.

Physical wear of orthopedic implants is inevitable. CoCr alloy samples, typically used in joint reconstruction, corrode rapidly after removal of the protective oxide layer. The behavior of CoCr pellets immersed in human serum, foetal bovine serum (FBS), synovial fluid, albumin in phosphate-buffered saline (PBS), EDTA in PBS, and water were studied using X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). The difference in the corrosive nature of human serum, water, albumin in PBS and synovial fluid after 5 days of immersion was highlighted by the oxide layer, which was respectively 15, 3.5, 1.5, and 1.5 nm thick. The thickness of an additional calcium phosphate deposit from human serum and synovial fluid was 40 and 2 nm, respectively. Co and Cr ions migrated from the bulk metal surface and were trapped in this deposit by the phosphate anion. This may account for the composition of wear debris from CoCr orthopedic implants, which is known to consist predominantly of hydroxy-phosphate compounds. Known components of synovial fluid including proteoglycans, pyrophosphates, phospholipids, lubricin, and superficial zone protein (SZP), have been identified as possible causes for the lack of significant calcium phosphate deposition in this environment. Circulation of these compounds around the whole implant may inhibit calcium phosphate deposition.     

磷酸钙骨水泥替代骨的制备及其细胞生物相容性实验研究

目的为了修复骨缺损,研制适宜的骨移植人工替代材料。方法制备出磷酸钙骨水泥（CPC）,检测其成分,并与骨髓基质干细胞共同培养,研究其细胞生物相容性及对骨髓基质干细胞成骨能力的影响。结果所制备磷酸钙骨水泥主要成分为低结晶度的羟基磷灰石（HA）,对骨髓基质干细胞的生存、增殖能力及对其成骨特性的保存无影响。结论所制备磷酸钙骨水泥细胞生物相容性良好,是适宜的骨缺损修复材料。     

Comparison of the osteogenesis and fusion rates between activin A/BMP-2 chimera (AB204) and rhBMP-2 in a beagle's posterolateral lumbar spine model

Background Context

Activin A/BMP-2 chimera (AB204) could promote bone healing more effectively than recombinant bone morphogenetic protein 2 (rhBMP-2) with much lower dose in a rodent model, but there is no report about the effectiveness of AB204 in a large animal model.

Development of a novel PCR assay for the identification of the black yeast, Exophiala (Wangiella) dermatitidis from adult patients with cystic fibrosis (CF)

Cystic fibrosis (CF) patients may suffer increased morbidity and mortality through colonisation, allergy and invasive infection from fungi. The black yeast, Exophiala dermatitidis (synonym Wangiella dermatitidis) has been found with increasing frequency in sputum specimens of CF patients, with reported isolation rates ranging from 1.1 to 15.7%. At present, no diagnostic PCR exists to aid with the clinical laboratory detection and identification of this organism. A novel species-specific PCR-based assay was developed for the detection of E. dermatitidis, based on employment of rDNA operons and interspacer (ITS) regions between these rDNA operons. Two novel primers, (designated ExdF & ExdR) were designed in silico with the aid of computer-aided alignment software and with the alignment of multiple species of Exophiala, as well as with other commonly described yeasts and filamentous fungi within CF sputum, including Candida, Aspergillus and Scedosporium. An amplicon of approximately 455 bp was generated, spanning the partial ITS1 region – the complete 5.8S rDNA region – partial ITS2 region, employing ExdF (forward primer [16-mer], 5′-CCG CCT ATT CAG GTC C-3′ and ExdR (reverse primer [16-mer], 5′-TCT CTC CCA CTC CCG C-3′, was employed and optimised on extracted genomic DNA from a well characterised culture of E. dermatitidis, as well as with high quality genomic DNA template from a further 16 unrelated fungi, including Candida albicans, C. dubliniensis, C. parapsilosis, C. glabrata, Scedosporium apiospermum, Penicillium sp., Aspergillus fumigatus, Aspergillus versicolor, Pichia guilliermondii, Rhodotorula sp., Trichosporon sp., Aureobasidium pullulans, Fusarium sp., Mucor hiemalis, Bionectria ochroleuca, Gibberella pulicaris. Results demonstrated that only DNA from E. dermatitidis gave an amplification product of the expected size, whilst none of the other fungi were amplifiable. Subsequent employment of this primer pair detected this yeast from mycological cultures from 2/50 (4%) adult CF patients. These two patients were the only patients who were previously shown to have a cultural history of E. dermatitidis from their sputum. E. dermatitidis is a slow-growing fungus, which usually takes up to two weeks to culture in the microbiology laboratory and therefore is slow to detect conventionally, with the risk of bacterial overgrowth from common co-habiting pan- and multiresistant bacterial pathogens from sputum, namely Pseudomonas aeruginosa and Burkholderia cepacia complex organisms, hence this species-specific PCR assay may help detect this organism from CF sputum more specifically and rapidly. Overall, employment of this novel assay may help in the understanding of the occurrence, aetiology and epidemiology of E. dermatitidis, as an emerging fungal agent in patients with CF.     

聚羟基丁酸酯复合骨髓基质细胞构建组织工程骨修复兔下颌骨缺损

目的：探讨以聚羟基丁酸酯（PHB）作为骨组织工程支架的可行性.方法：体外培养兔骨髓基质细胞（BMSCs）,使其向成骨细胞分化后接种于PHB支架上,植入兔下颌角骨缺损中,以单纯缺损、单纯植入材料、植入新鲜骨髓加材料作为对照.4、8、1 2、24周分别处死各组家兔2只,行大体标本、X线摄片、组织学及扫描电镜观察新骨形成情况.结果：实验组24周大部分材料被骨性组织取代,修复骨缺损效率较对照组高.结论：PHB可以作为组织工程材料中的一种来修复骨缺损.