Preparation of bioactive Ti metal surface enriched with calcium ions by chemical treatment

A calcium solution treatment was applied to a NaOH-treated titanium metal to give it bioactivity, scratch resistance and moisture resistance. The titanium metal was soaked in a 5 M NaOH solution and then a 100 mM CaCl₂ solution to incorporate Ca²⁺ ions into the titanium metal surface by ion exchange. This treated titanium metal was subsequently heated at 600 °C and soaked in hot water at 80 °C. The NaOH treatment incorporated ～5 at.% Na⁺ ions into the Ti metal surface. These Na⁺ ions were completely replaced by Ca²⁺ ions by the CaCl₂ treatment. The number of Ca²⁺ ions remained even after subsequent heat and water treatments. Although the NaOH–CaCl₂-treated titanium metal showed slightly higher apatite-forming ability in a simulated body fluid than the NaOH-treated titanium metal, it lost its apatite-forming ability during the heat treatment. However, subsequent water or autoclave treatment restored the apatite-forming ability of the NaOH–CaCl₂-heat-treated titanium metal. Although the apatite-forming ability of the NaOH-heat-treated titanium metal decreased dramatically when it was kept at high humidity, that of NaOH–CaCl₂-heat-water-treated titanium metal was maintained even in the humid environment. The heat treatment increased the critical scratch resistance of the surface layer of the NaOH–CaCl₂-treated titanium metal remarkably, and it did not deteriorate on subsequent water treatment.     

硫化氢及硫化氢与细胞内钙离子关系的研究概况

硫化氢作为一种新型的气体信号分子,广泛参与机体各个系统的生理活动。硫化氢能够通过改变细胞内钙离子的浓度对细胞的功能状态产生一定影响。表皮细胞内存在胱硫醚-γ-裂解酶和胱硫醚-β-合酶体系,烧伤应激会抑制大鼠表皮细胞内硫化氢/胱硫酶-γ-裂解酶体系功能,使硫化氢生成减少。严重烧伤应激使多种脏器出现功能障碍,同时再灌注损伤促使机体产生大量氧自由基。各种酶类的激活、炎性因子的释放可加重细胞的水肿,在细胞内发生钙离子超载。因此研究硫化氢对于表皮细胞的作用机制,进一步探究硫化氢在表皮细胞内是否通过钙离子介导信号转导途径具有重要意义。本文对现有国内外关于硫化氢及硫化氢与细胞内钙离子关系的研究进行总结,旨在丰富硫化氢功能研究的理论基础,研究硫化氢与胞内钙离子浓度的相关性从而探讨钙离子是否在硫化氢胞内的信号通路中发挥一定的作用。     

Histological study of a case of recurrent olecranon bursitis with mixed calcium pyrophosphate dihydrate and apatite crystal deposits

Summary This is the report of a light and transmission electron microscopic study of an olecranon bursitis and of the adjacent distal tricipital tendon in an 83 year-old man. The data are compared with those of a similar study in the same patient performed 2 years ago.Calcium pyrophosphate dihydrate crystals were observed in the bursal fluid, in the inner part of the bursal wall (extracellular localization and intracellular phagocytosis) as well as in the peripheral part of the tendon. In addition, small apatite deposits were observed in the bursa and tendon by electron microscopy. The origin of these bursal deposits is discussed; it is suggested that they may be related to an exchange from the tendon to the remodelled bursal wall.This study was partially subsidized by the Swiss Federal Commission for Rheumatic Diseases (Bern)     

Preparation and characterization of a novel strontium-containing calcium phosphate cement with the two-step hydration process

A novel Sr-containing calcium phosphate cement (CPC) with excellent compressive strength, good radiopacity and suitable setting time was developed in this work. The two-step hydration reaction resulted in a high compressive strength, with a maximum of up to 74.9 MPa. Sr was doped into the calcium-deficient hydroxyapatite as a hydrated product during the hydration reaction of the CPC. Because of the existence of Sr element and the compact microstructure after hydration, the Sr-containing CPC shows good radiopacity. It is expected to be used in orthopedic and maxillofacial surgery for bone defects repairing.     

Tribological characterization of a biocompatible thin film of UHMWPE on Ti6Al4V and the effects of PFPE as top lubricating layer

Ultra-high molecular weight polyethylene (UHMWPE) thin film was coated onto Ti6Al4V alloy specimens using dip coating method. Tribological performance of this coating (thickness of 19.6±2.0 μm) was evaluated using 4 mm diameter Si₃N₄ ball counterface in a ball-on-disk tribometer. Tests were carried out for different normal loads (0.5, 1.0, 2.0 and 4.0 N) and rotational speeds of the disk (200 and 400 rpm). UHMWPE coating formed in this study exhibits high hydrophobicity with water contact angle of 135.5±3.3° and meets the requirements of cytotoxicity test using the ISO 10993-5 elution method. This coating shows low coefficient of friction (0.15) and high wear durability (>96,000 cycles) for the tested conditions. PFPE overcoat on UHMWPE has further increased the wear durability of UHMWPE coating as evaluated at even higher rotational speed of 1000 rpm.     

Identification of a bioactive core sequence from human laminin and its applicability to tissue engineering

Finding bioactive short peptides derived from proteins is a critical step to the advancement of tissue engineering and regenerative medicine, because the former maintains the functions of the latter without immunogenicity in biological systems. Here, we discovered a bioactive core nonapeptide sequence, PPFEGCIWN (residues 2678–2686; Ln2-LG3-P2-DN3), from the human laminin α2 chain, and investigated the role of this peptide in binding to transmembrane proteins to promote intracellular events leading to cell functions. This minimum bioactive sequence had neither secondary nor tertiary structures in a computational structure prediction. Nonetheless, Ln2-LG3-P2-DN3 bound to various cell types as actively as laminin in cell adhesion assays. The in vivo healing tests using rats revealed that Ln2-LG3-P2-DN3 promoted bone formation without any recognizable antigenic activity. Ln2-LG3-P2-DN3-treated titanium (Ti) discs and Ti implant surfaces caused the enhancement of bone cell functions in vitro and induced faster osseointegration in vivo, respectively. These findings established a minimum bioactive sequence within human laminin, and its potential application value for regenerative medicine, especially for bone tissue engineering.     

伯明翰髋关节表面置换对比全髋关节置换的效果及金属离子水平：系统评价与Meta分析

文题释义：全髋关节置换：已被证实是治疗退行性髋关节病的有效方式,并且是治疗老年髋关节病终末阶段的金标准。由于受到假体寿命的影响,对于运动量大的年轻人来说,全髋关节置换并不是此类患者的首选治疗方式,过早置换髋关节可能会导致远期的二次手术。髋关节表面置换：随着髋关节表面置换假体的不断更新,金属对金属髋关节表面置换,特别是伯明翰髋关节表面置换,已成为全髋关节置换的有效替代方案。由于担心全髋关节置换假体寿命的因素,对于年轻患者而言,伯明翰髋关节表面置换是一种相对更为保守的手术方式。背景：全髋关节置换是治疗老年髋关节病终末阶段的金标准,但对于运动量大的年轻人来说,伯明翰髋关节表面置换已成为全髋关节置换的有效替代方案。伯明翰髋关节表面置换是否比全髋关节置换有优势尚无定论。目的：系统评价伯明翰髋关节表面置换对比全髋关节置换临床疗效和金属离子水平。方法：计算机检索PubMed、EMBASE、the Cochrane library和Web of Science数据库,纳入数据库中所有关于伯明翰髋关节表面置换对比全髋关节置换的临床对照研究,检索年限自各数据库建库至2018-11-30。提取文献资料并进行文献质量评价后,运用RevMan 5.3软件进行Meta分析。结果与结论：①共纳入12篇符合要求的文献,包括2 317例患者,其中伯明翰髋关节表面置换组1 279例,全髋关节置换组1 038例;②Meta分析结果显示,在主要结局指标上,伯明翰髋关节表面置换组在短期随访中与全髋关节置换组差异无显著性意义[RR=0.13,95%CI(0.02,1.01),P=0.05],但是在长期随访中伯明翰髋关节表面置换具有更低的翻修率[RR=0.27,95%CI(0.15,0.50),P < 0.000 1];③在次要结局指标的功能评分上,伯明翰髋关节表面置换组在短期随访的Harris髋关节评分和改良Harris髋关节评分方面优于全髋关节置换组(P < 0.05);但是在长期随访Harris髋关节评分和加州大学洛杉矶分校评分以及任何时间段的髋关节西安大略和麦克马斯特大学骨关节炎评分方面,2组差异均无显著性意义(P > 0.05);④最后在金属离子水平中,无论是短期随访还是长期随访,伯明翰髋关节表面置换在钴离子水平方面与全髋关节置换比较差异均无显著性意义(P < 0.05)。而铬离子水平则表明,短期随访中伯明翰髋关节表面置换与全髋关节置换差异无显著性意义(P=0.55);但是长期随访中发现,伯明翰髋关节表面置换较全髋关节置换释放出更多的铬离子,组间差异有显著性意义(P=0.03);⑤综上所述,与全髋关节置换相比,伯明翰髋关节表面置换的翻修率和总体并发症更少,髋关节功能更好,铬离子水平更高。此结论仍需要进一步纳入大量大样本、多中心、高质量的随机对照试验加以论证。ORCID: 0000-0002-5259-5160(范智荣) 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

Amino acid release from the cerebral cortex of the rabbit, its relationship with the electrocorticogram

The rate of release of five amino acids (alanine, glutamine, glutamic acid, glycine, GABA) from the surface of the sensorimotor cortex has been determined in rabbits under local anesthesia immobilized with gallamine. Concomitant recording of the electroencephalogram and of blood pressure has been carried out. The scope of the research was to determine if a difference in the release of these aminoacids could be correlated with variations in cerebral electrical activity. Two open-ended silver cylinders were adapted to the cortex and filled with saline. Every 10 min, the liquid was removed and assayed using a dansylating procedure followed by thin layer chromatographic separation and fluorimetric determination of the amino acids. The EEG of non treated animals, followed for a period of 100 min, remained synchronized for the majority of the recording; the biochemical determinations indicated a slight but constant fall in the rate of release of all the amino acids. A significant increase in the release accompanied the EEG desynchronisation induced either with eserine (0.2 mg/kg), amphetamine (2 mg/kg), or with electrical stimulation of the reticular formation.     

Bony integration of titanium implants with a novel bioactive calcium titanate (Ca(4) Ti(3) O(10) ) surface treatment in a rabbit model

Nowadays total joint replacement is an indispensable component of modern medicine. The surfaces characteristics of cementless prostheses may be altered to achieve an accelerated and enduring bony integration. Classic surface coatings bear the risk of loosening or flaking from the implant body. This risk is excluded by the chemical conversion of the naturally existing TiO(2) surface layer into calcium titanate. The aim of this experimental animal study was to investigate the bony integration of implants with a new calcium titanate surface (Ca(4) Ti(3) O(10) ) compared with a conventional standard Ti6Al4V surface. Cylindrical implants, made of titanium alloy (Ti6Al4V) were implanted in both lateral femoral condyles of New Zealand white rabbits. In each animal, an implant with and without surface treatment was inserted in a blinded manner. Animals were sacrificed after 4, 12, and 36 weeks, respectively. The axial pull-off forces were determined for 25 animals using a universal testing machine (Zwick Z010, Ulm, Germany). Furthermore, a histological analysis of the bony integration of the implants was performed in 12 specimens. In general, the pull-off forces for untreated and treated implants increased with longer survival times of the rabbits. No significant difference could be shown after 4 weeks between treated and untreated implants. After 12 weeks, the treated implants revealed a statistical significant higher pull-off force. After 36 weeks, the pull-off forces for treated and untreated implants aligned again. Titanium implants treated with calcium titanate, may offer an interesting and promising implant surface modification for endoprosthetic implants. They might lead to an accelerated osseointegration of total hip and knee replacements. ? 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A 100A:2710-2716, 2012.     

Cell surface measurements of ATP release from single pancreatic β cells using a novel biosensor technique

 To examine the possibility that ATP modulates insulin secretion by an autocrine mechanism, we measured the local concentration of released ATP at the surface of a single pancreatic β cell by a new biosensor technique, using PC12 cells expressing ligand-gated cation channels, P2X₂ receptors. Upon application of glucose or glibenclamide, a series of current spikes, whose amplitude equates to an ATP concentration of over 25 μM, were recorded from a PC12 cell using the whole-cell patch-clamp technique, when placed near a rat pancreatic β cell at 37°C. The current response was inhibited by cooling (below 30°C) or by applying an ATP-hydrolysing enzyme (apyrase) or a P2 receptor blocker (suramin). Thus, it is concluded that pancreatic β cells secrete ATP in response to glucose stimulation, thereby increasing the ATP concentration close to the cell surface sufficiently high enough to enhance insulin secretion from the pancreatic β cells. Received: 8 May 1998 / Received after revision: 4 August 1998 / Accepted: 10 August 1998     

IgA肾病患者血清IgA1诱导正常人肾小球系膜细胞钙离子释放、转化生长因子β表达上调和纤连蛋白分泌

目的:研究IgA肾病患者血清IgA₁对正常人肾小球系膜细胞(HMC)活化及分泌炎症硬化因子的刺激作用,比较与正常人IgA₁的差异,探讨IgA肾病患者血清IgA₁病理生理作用。方法:亲和层析提取血清IgA₁,加热聚合(aIgA₁),激光共聚焦显微镜检测细胞内游离钙离子(Ca²⁺)释放,RT-PCR法检测细胞内TGF-β mRNA表达,间接竞争ELISA法检测细胞上清纤连蛋白(Fn)含量。结果:IgA肾病患者aIgA₁呈时间依赖性诱导正常HMC细胞内游离Ca²⁺释放、TGF-β mRNA表达和Fn分泌,作用趋势与正常人aIgA₁相同,高峰时间分别为孵育后60 s、24-36 h和36-48 h,但作用强度显著高于正常人aIgA₁;在作用高峰时间,患者组和正常人组Fluo-3最大相对荧光强度增加值分别为(95.83±11.43)和(55.88±12.72),TGF-β／GAPDH的比值分别为0.96±0.06和0.74±0.02,Fn含量分别为(6.45±0.18)μg/L和(5.54±0.43)μg/L,均有显著差异(P<0.05)。结论: IgA肾病患者血清IgA₁可以诱导体外培养的正常HMC活化并分泌炎症硬化因子,其作用较正常人IgA₁强,提示患者血清IgA₁分子与肾小球系膜细胞直接相互作用可能是IgA肾病发病机制之一。     

Tx3-4 a toxin from the venom of spider Phoneutria nigriventer blocks calcium channels associated with exocytosis

The purpose of the present work was to investigate the pharmacological action of a calcium channel-blocking toxin from the venom of the spider Phonetic nigriventer, Tx3-4 on calcium channels coupled to exocytosis of synaptic vesicles. Tx3-4 blocked KCl-induced exocytosis of synaptic vesicles with an IC50 of 1.1 nM. To investigate whether the target of Tx3-4 overlaps with known calcium channels that mediate calcium entry and exocytosis, we used omega-toxins that interact selectively with neuronal calcium channels. The results indicate that the main population of voltage-sensitive calcium channels altered by Tx3-4 is P/Q calcium channels. In conclusion, Tx3-4 is a potent inhibitor of calcium channels involved in the KCl-induced exocytosis of synaptic vesicles in brain cortical synaptosomes.     

Differential mediator release from basophils of allergic and non-allergic asthmatic patients after stimulation with anti-IgE and C5a

The differentiation between allergic and non-allergic asthma is a common and important challenge for the clinician. Until now, no in vitro diagnostic characteristics have been described to distinguish between these types. To examine the diagnostic value of a basophil stimulation test, we compared anti-IgE- and C5a-induced mediator release from peripheral blood leucocytes in different types of bronchial asthma. Peripheral blood leucocytes (PBL) from 10 aspirin-sensitive asthmatics (ASA), 12 non-allergic asthmatics without aspirin intolerance (NAA), seven allergic asthmatics (AA), and nine healthy controls were prepared by dextran sedimentation. After priming with interleukin-3 (IL-3) PBL were stimulated with anti-IgE and C5a, and the release of histamine (HR) and sulfidoleukotrienes (LTR) in the supernatant was compared. Additionally, purified leucocyte fractions were studied to determine the cellular source of mediator release. Upon stimulation with anti-IgE LTR was slightly, but not significantly, lower in ASA and NAA compared to AA and controls. In contrast, C5a-triggered LTR was significantly higher in ASA (14.4 +/- 12.88 pg/105 cells) and NAA (22.9 +/- 22.61 pg/105 cells) than in AA (9.6 +/- 3.29 pg/105 cells) and controls (7.5 +/- 7.19 pg/105 cells) (P < 0.05). This difference between ASA and NAA vs. AA and controls was even more pronounced when determining the quotient C5a-/anti-IgE-induced LTR (P < 0.001). At an optimal cut-off point of 1.0, calculated by relative operating characteristics (ROC) analysis, the positive predictive value for a donor to belong to ASA or NAA was 0.94. No significant differences could be found in HR between the asthmatic patient groups and healthy controls in either condition. As cellular source of LTR and HR the basophil could be determined. Determination of anti-IgE- and C5a-induced LTR from basophils allows us to discriminate between allergic and non-allergic asthmatic patients. For diagnostic purposes the quotient C5a-/anti-IgE-induced LTR is more significant than considering a single parameter. ASA cannot be distinguished from NAA.     

Stimulus-evoked release of neuropeptides is enhanced in sensory neurons from mice with a heterozygous mutation of the Nf1 gene

Neurofibromatosis type I is a common autosomal dominant disease characterized by formation of multiple benign and malignant tumors. People with this disorder also experience chronic pain, which can be disabling. Neurofibrinomin, the protein product of the NF1 gene (neurofibromin gene (human)), is a guanosine triphosphate activating protein for p21(ras). Loss of NF1 results in an increase in activity of the p21(ras) transduction cascade. Because of the growing evidence suggesting involvement of downstream components of the p21(ras) transduction cascade in the sensitization of nociceptive sensory neurons, we examined the stimulus-evoked release of the neuropeptides, substance P and calcitonin gene-related peptide, from primary sensory neurons of mice with a mutation of the Nf1 gene (neurofibromin gene (mouse)) (Nf1+/-). Measuring immunoreactive substance P and immunoreactive calcitonin gene-related peptide by radioimmunoassay, we demonstrated that capsaicin-stimulated release of neuropeptides is three to five-fold higher in spinal cord slices from Nf1+/- mice than from wildtype mouse tissue. In addition, the potassium and capsaicin-stimulated release of immunoreactive calcitonin gene-related peptide from cultures of sensory neurons isolated from Nf1+/- mice was more than double that from cultures of wildtype neurons. Treatment of wildtype sensory neurons with nerve growth factor for 5-7 days mimicked the enhanced stimulus-evoked release observed from the Nf1+/- neurons. When nerve growth factor was removed 48 h before conducting release experiments, nerve growth factor-induced augmentation of immunoreactive calcitonin gene-related peptide release from Nf1+/- neurons was more pronounced than in Nf1+/- sensory neurons that were treated with nerve growth factor continuously for 5-7 days. Thus, sensory neurons from mice with a heterozygous mutation of the Nf1 gene that is analogous to the human disease neurofibromatosis type I, exhibit increased sensitivity to chemical stimulation. This augmented responsiveness may explain the abnormal pain sensations experienced by people with neurofibromatosis type I and suggests an important role for guanosine triphosphate activating proteins, in the regulation of nociceptive sensory neuron sensitization.     

Establishment and characterization of a new human mesothelioma cell line (T-85) from malignant peritoneal mesothelioma with remarkable thrombocytosis

A mesothelioma cell line, termed T-85, was established from a patient with malignant peritoneal mesothelioma and remarkable thrombocytosis (1.4 × 10⁶/mm³). Electron microscopically, two types of mesothelioma cells have been characterized; the major type of cells with dense-cored granules in the cytoplasm and the minor one with evenly dense granules. Immunologically, the cells showed staining for inter-leukin-6 (IL-6), cytokeratin, collagen type IV, vimentin, laminin, fibronectin and Factor VIII-related antigen. Quanti-tation by ELISA revealed a high concentration of IL-6 in T-85 cell culture supernatants. RT-polymerase chain reaction of T-85 cells showed two positive bands of cDNA at 628 and 251 base pairs indicating the constitutive expression of IL-6 and IL-6 receptor mRNA. Moreover, prominent pro-platelet process formation activity in T-85 cell culture supernatants indicated the presence of a thrombopoietic activity due mainly to IL-6 but not the c-MpI ligand or erythropoietin. However, the fact that 15% of PPF activity remained in the supernatants treated with anti-IL-6 antibody indicated the presence of another thrombopoietic substance. T-85 is so far the first mesothelioma cell line derived from a case with remarkable thrombocytosis.     

采用一种新型动态牙合力加载装置研究力对镍铬烤瓷合金中镍离子释放的影响

目的 设计一种新型动态力加载装置,研究牙合力对镍铬烤瓷合金中镍离子释放的影响。方法 依据人咀嚼的平均力(45 N)和频率(80次/min)设计一种动态牙合力加载装置。运用该装置研究3种常用镍铬烤瓷合金（上齿牌、Stellite、BEGO）分别在pH 2.3和pH 7.0的人工唾液中镍离子的释放量。结果 新型动态牙合力加载装置能够模拟咀嚼频率进行人体平均力的加载。当pH 2.3时,上齿牌、Stellite和BEGO 3种镍铬烤瓷合金镍离子释放量分别为 6.9(2.07) μg/cm2、3.7(0.662) μg/cm2和5.88(1.57) μg/cm2;当pH 7.0时,分别为0.272(0.059) μg/cm2、0.144(0.014) μg/cm2和0.435(0.053) μg/cm2。同种镍铬烤瓷合金材料在pH 2.3的人工唾液中镍离子的释放量均远大于在pH 7.0环境下的释放量,两者具有显著的统计学差异（P<0.01）。结论 动态力加载装置可有效地被用于体外研究牙合力对镍离子释放的影响。酸性环境可明显加快镍铬烤瓷合金中镍离子释放。本研究中Stellite镍铬烤瓷合金释放的镍离子量相对最少。     

Projections from the superior colliculus to a region of the central mesencephalic reticular formation (cMRF) associated with horizontal saccadic eye movements

Summary Radioactive wheatgerm agglutinin (WGA) and horseradish peroxidase (HRP) were injected into portions of the mesencephalic reticular formation at sites where electrical stimulation induced either small or large contralateral horizontal saccadic eye movements. We have designated this region as the Central MRF (cMRF). It contains both cells and fiber tracts, including the efferent output of the superior colliculus (SC), destined for the dorsal tegmental decussation and the predorsal bundle. Cells labelled by WGA and HRP injections were found in the intermediate and deep layers of the superior colliculus and the adjacent central gray matter on the ipsilateral side. Injections into the dorsal cMRF, at sites where small saccades were induced, caused labelling of cells in the rostral intermediate layer of SC. Injections into the ventral cMRF, at points where large saccades were elicited, caused labelling of cells in the caudal intermediate layer of SC. The deepest layers of SC and the adjacent central gray were also labelled from the small eye movement region of dorsal cMRF. We interpret these findings to indicate that the intermediate layers of SC send axonal projections to the horizontal eye movement region of the MRF in a topographic fashion. The projection from the intermediate layer is organized so that regions in SC and cMRF related to small or to large eye movements are interconnected. The results support the hypothesis that cMRF is a topographically organized area, involved, like SC, in the control of eye movements. Since both cMRF and the superior colliculus project to areas of the pons and medulla where saccadic eye movements are produced, they could give rise to parallel pathways for the generation of contralateral saccades.Abbreviations III oculomotor nucleus - IV trochlear nucleus - ap area pretectalis - BC brachium conjunctivum - BSC brachium of the superior colliculus - cg central gray - cMRF central MRF - d deep layer of SC - DAB diaminobenzidine - EOG electro-oculography - h habenula nuclei - HRP horseradish peroxidase - iC interstitial nucleus of Cajal - ic inferior colliculus - li nucleus limitans - mg medial geniculate body - MLF medial longitudinal fasciculus - nIII oculomotor nerve - nIV trochlear nerve - on olivary nucleus - p pulvinar - PC posterior commissure - riMLF rostral interstitial nucleus of the MLF - rn red nucleus, pars magnocellularis - rnp red nucleus, pars parvocellularis - s superficial layer of SC - SC superior colliculus - sl sublentiform nucleus - sn substantia nigra - TMB tetramethyl benzidine - TR tractus retroflexus - WGA wheatgerm agglutinin Supported by NIH Research grant EY 02296, Deutsche Forschungsgemeinschaft grant SFB 200/A3 and Core Center grant EY 01867     

Neutrophil lactoferrin release induced by IgA immune complexes differed from that induced by cross-linking of fcalpha receptors (FcalphaR) with a monoclonal antibody, MIP8a

The human IgA Fc receptor (FcalphaR, CD89) plays an important role in host defence against invading pathogens. To study the properties of the receptor, 12 MoAbs, namely, MIP7c, MIP8a, MIP9a, MIP10c, MIP11c, MIP14b, MIP15b, MIP38c, MIP59c, MIP65c, MIP68b and MIP71a, were generated. The inhibitory effects of the antibodies on FcalphaR functions were tested. Three of the antibodies, MIP7c, MIP8a and MIP59c, were able to block up to 90% of soluble FcalphaR binding to IgA-coated beads and 70-80% of neutrophil phagocytosis of IgA immune complexes (IC). MIP8a could also inhibit IgA IC-induced neutrophil lactoferrin release, while cross-linking of FcalphaR with MIP8a and anti-mouse IgG could elicit neutrophil lactoferrin release. However, IgA IC-induced lactoferrin release required both extracellular calcium and magnesium, whereas MIP8a-induced release did not require extracellular magnesium and only partially required extracellular calcium. In addition, the time course of IgA IC-induced lactoferrin release was slow. Lactoferrin was not detectable if the incubation time was less than 0.5 h. In contrast, MIP8a-induced lactoferrin release was fast. Lactoferrin could be detected within 5 min of incubation. Therefore, neutrophil lactoferrin release induced by IgA IC differed from that induced by cross-linking of FcalphaR with MIP8a.     

Synthesis of Polystyrene‐block‐Poly(methyl methacrylate) with Fluorene at the Junction: Sequential Anionic and Controlled Radical Polymerization from a Single Carbon

Polystyrene‐block‐poly(methyl methacrylate) (PS‐b‐PMMA) has been synthesized by sequential anionic and reverse atom transfer radical polymerization (ATRP) or a variation of nitroxide mediated polymerization (NMP) from a single initiating site, specifically the 9‐carbon on 2,7‐dibromofluorene or fluorene. The addition of the second arm (PS) relied on thermal decomposition of 2,2′‐azoisobutyronitrile (AIBN) to generate radicals, abstracting the 9‐H on the polymer‐bound fluorene species to form the initiating radical. Styrene was not present in the reaction mixture when AIBN was decomposed, preventing competition between addition across the monomeric alkene and hydrogen abstraction from the fluorene. After 1 h, styrene was introduced and mediation of the subsequent radical polymerization was achieved by the presence of CuCl₂/ligand or TEMPO. Characterization of the diblock copolymers by gel permeation chromatography (GPC) revealed substantial shifts in number average molecular weight ( ) values compared to the anionically prepared PMMA macroinitiator, while polydispersity indices (PDI's) remained relatively low (typically < 1.5). Characterization by UV detection with GPC (at 310 nm) verified that the diblock polymer is chromophore‐bound, which was further verified by UV‐vis spectroscopy of the isolated diblock.