Electrochemical characterization of novel Ag-based brazing alloys for dental applications

ObjectiveTaking into account that clinical data have proven the decomposition of Ag brazing alloys used in the production of orthodontic appliances the aim of this study was to develop new Ag based soldering alloys free of Cu and Zn.MethodsFour commercially available Ag brazing alloys were selected and their electrochemical properties were compared to the following experimental alloys: Ag12Ga, Ag10Ga5Sn, Ag20In and Ag7Sn. 112 disk shape specimens were prepared for each alloy and their electrochemical properties were evaluated by Open Circuit Potential (OCP), linear sweep voltametry (LSV), cyclic polarization (CP) and electrochemical impedance spectroscopy (EIS) in a NaCl 0.9% and a Ringer’s electrolyte solution.ResultsThe experimental alloys combined higher OCP and E_corr with lower I_corr values. The impedance values of the commercial alloys were lower showing that any surface layers formed are not protective and steady compared to those of the novel ones. In conclusion experimental alloys demonstrated enhanced electrochemical properties.SignificanceIn and Sn showed a more beneficial effect on electrochemical properties compared to Ga and thus can be considered as a promising option for the development of a new family of Ag brazing alloys with increased biocompatibility.     

Responses of human hepatoma HepG2 cells to silver nanoparticles and polycyclic aromatic hydrocarbons

The nanotechnology has revolutionized the global market with silver nanoparticles (AgNP) occupying a prominent position due to their remarkable anti-bacterial properties. However, there is no data about the adverse and toxic effects of associations of AgNP and ubiquitous compounds, such as polycyclic aromatic hydrocarbons (PAH). In the current study, we investigated the responses of HepG2 cells to realistic concentrations of AgNP (0.09, 0.9, and 9?ng ml^?1) and mixture of PAH (30 and 300?ng ml^?1), separately and in association. Cell viability and cytotoxicity (neutral red retention and MTT production assays) and proliferation (crystal violet [CV] assay), xenobiotic efflux transporter activity (rhodamine B accumulation assay), ROS levels (dichlorodihydrofluorescein diacetate assay), and lipid peroxidation (pyrenylphosphine-1-diphenyl assay) were analyzed. There was no decreases of cell viability after exposure to AgNP, PAH and most of AgNP?+?PAH associations, but increases of cell viability/number (CV assay) occurred. Efflux transporter activity was not affected, with exception of one AgNP?+?PAH associations, ROS levels increased, but lipid peroxidation decreased. Some toxicological interactions occurred, particularly for the highest concentrations of AgNP and PAH, but there is no evidence that these interactions increased the toxicity of AgNP and PAH.     

Food-induced contact urticaria syndrome (CUS) in atopic dermatitis: reproducibility of repeated and duplicate testing with a skin provocation test, the skin application food test (SAFT)

IgE-mediated contact urticaria syndrome (CUS) is one of the manifestations of allergy in childhood atopic dermatitis (AD). Allergens such as foods and animal products penetrate the skin easily. They can then cause urticarial reactions in sensitized individuals. A provocation test system for foods, called the skin application food test (SAFT), has been developed. Over more than 5 years, a group of 175 patients with AD was built-up and investigated in a prospective follow-up study with SAFT. SAFT was more frequently positive in AD children aged 6–2 years than in older children. In several children of this population (Group 1), we repeated SAFT within a period of 1 year. In another unrelated group of children (Group 2–1), we compared the results of 'original' SAFT and SAFT using square chambers (Van der Bend) or Silver patches. In the 3rd group (Group 2–2) we compared'original' SAFT with SAFT using big Finn Chambers. The agreement between the tests was high: in Group 1, we observed 88 to 93% concordant scores, and in Group 2, the scores were 96% to 100%. Statistically, the K coefficient ranged from 0.71–0.87 in Group 1, and from 0.83–1.00 in Group 2. SAFT is therefore highly reproducible. Agreement was at least 88% between the scores (the lowest K value observed was at least 0.71).     

Chlorhexidine and silver-sulfadiazine coated central venous catheters in haematological patients—a double-blind,randomised, prospective,controlled trial

Background Central venous catheters (CVCs) are essential for the intensive care of patients with haematological illness. Catheter-related infections (CRI) are an important problem in modern medicine, which may lead to life-threatening situations, to prolonged hospitalisation and increased cost. In immunocompromised patients suffering from haemato-oncological diseases, CRI is a significant factor for adverse outcome. Several clinical studies have shown that CVCs coated with antiseptics such as chlorhexidine and silver-sulfadiazine (CHSS) reduce the risk of catheter-related bacteraemia. Most studies, however, were performed on intensive care patients not suffering from chemotherapy-induced immunosuppression.Patients and methods A prospective double-blind, randomised, controlled trial was performed to investigate the effectiveness of CHSS-coated catheters in haemato-oncological patients. A total number of 184 catheters (median duration of placement, 11 days) were inserted into 184 patients (male 115, female 69), of which 90 were antiseptically coated. After removal, all catheters were investigated for bacterial growth.Main results Catheters coated with CHSS were effective in reducing the rate of significant bacterial growth on either the tip or subcutaneous segment (26%) compared to control catheters (49%). The incidence of catheter colonisation was also significantly reduced (12% coated vs 33% uncoated). Data obtained show a significant reduction of catheter colonisation in CHSS catheters. There was no significant difference in the incidence of catheter-related bacteraemia (3% coated vs 7% uncoated). However, due to the overall low rate of CRI, we could not observe a significant reduction in the incidence of catheter-related bacteraemia.Conclusion Our data show that the use of CHSS catheters in patients with haematological malignancy reduces the overall risk of catheter colonisation and CRI, although the incidence of catheter-related bacteremia was similar in both groups.     

Improvements to the enzyme-developed radial immunodiffusion technique

An enzyme-developed radial immunodiffusion technique, previously known as the diffusion-in-gel enzyme-linked immunosorbent assay (DIG-ELISA), has been improved in two ways: (a) antibody-containing spots have been made larger and more distinct by revealing them with a mixture of hydrogen peroxide, 3,3′-diaminobenzidine and nickel, and further intensification of the ensuing spots with silver; (b) the reliability of the method has been enhanced by chemically coupling the antigen to a layer of a polyamino acid (poly(lysine, phenylalanine)) adsorbed to the bottom of the polystyrene petri dish. The usefulness of the improved technique is illustrated by reference to the measurement of serum concentrations of IgM and IgG, and in the assessment of antibody levels against a particulate antigen (erythrocytes).     

The effect of varying impact energy on diffuse axonal injury in the rat brain: a preliminary study

Diffuse axonal injury (DAI) is seen as widespread damage in the white matter of brain characterized by morphological changes to axons throughout the brain and brain stem. The current study attempted to investigate the effect of increasing impact energy on the presence and severity of DAI in corpus callosum (CC). DAI was induced in adult male Sprague-Dawley rats using an injury model adapted from Marmarou et al. in 1994. A 450-g cylindrical brass weight was dropped from three different heights (2.0 m, 1.5 m and 1.0 m) on to a metal helmet affixed to the skull of the rats. In the sham group, rats underwent a surgical procedure with no impact. After a 24-h survival period the animals were transcardially perfused. The brain was removed and the cerebral hemispheres were sectioned with a vibrotome and stained by silver impregnation technique. The CC of all the impacted rats showed DAI in the form of beaded axons, retraction balls and vacuole-like enlargements. The axonal injury was most severe in the 2-m group, while mildest in the 1-m group. In the sham group, axons appeared to be normal. This study demonstrates evidence of graded DAI depending on the impact energy. Such data is useful for mathematical modeling of axonal injury in rat brain using the same impact parameters and potential determination of injury thresholds for neural trauma. Electronic Publication     

Warthin-Starry特殊染色、免疫组织化学和透射电镜在猫抓病病理诊断中的作用

目的 探讨Warthin-Starry银染色法、抗汉赛巴尔通体单克隆抗体和电镜在检测人巴尔通体感染、确诊猫抓病中的实用价值.方法 收集1998年1月至2008年12月诊断的77例符合猫抓病形态学改变的石蜡包埋淋巴结组织,分别使用Warthin-Starry银染色法和抗汉赛巴尔通体单克隆抗体的EnVision法进行病原体的检测.选择二者均检出丰富细菌的5例进行透射电镜观察.结果 (1)透射电镜查见汉赛巴尔通体呈多形性,圆形、椭圆形、短棒状、杆状,长0.489～1.110μm,宽0.333～0.534 tun,集群性生长.(2)61.0%(47/77)的病例Warthin-Starry银染色法查见排列成线、成簇、局灶性聚集的黑色、短小、棒状杆菌,细菌绝大多数分布在靠近被膜下的坏死灶内,以存在于细胞外为主.(3)72.7%(56/77)的病例抗汉赛巴尔通体单克隆抗体阳性表达,阳性信号主要呈点状、颗粒状,少数呈线样勾勒出细菌形状,信号定位与Warthin-Starry银染色法一致.(4)59.7%(46/77)的病例Warthin-Starry银染色和抗汉赛巴尔通体单克隆抗体染色均阳性.两种方法联用,病原体总体检出率为74.0%(57/77).二种方法检出率的差异具有统计学意义(P＜0.05).结论 应用Warthin-Starry银染色法、免疫组织化学和电镜技术检测猫抓病病原体能达到确诊猫抓病的目的 ,抗汉赛巴尔通体单克隆抗体染色是较Warthin-Starry银染色更理想的检测方法.     

A multiplex methylation PCR assay for identification of uniparental disomy of chromosome 7

Uniparental disomy of chromosome 7 (UPD7) is associated with abnormal phenotypic effects because of inappropriate expression of imprinted genes on chromosome 7. Based on the differential methylation of the promoter region of the imprinted PEG1/MEST locus at 7q32, we designed a multiplex methylation PCR (mPCR) assay to rapidly distinguish UPD7 from biparental inheritance of chromosome 7. Primers were designed to produce different sized PCR amplicons based on the parent of origin-specific methylation at this locus; electrophoresis of PCR amplicons showed a 189-bp product from the methylated maternal allele and a 109-bp product from the unmethylated paternal allele. This mPCR assay correctly predicted the chromosome 7 imprinting status in normal control and UPD7 samples. Previous assays for UPD7 required genotyping of the proband and parents, or separate maternal- and paternal-specific mPCR reactions. The advantage of this assay is that parental samples are not required and that amplification of both alleles in the same reaction is simpler and provides an internal control. This multiplex mPCR assay will be useful in screening for UPD7 in patients with Silver-Russell syndrome (SRS; also Russell-Sliver syndrome, RSS), primordial growth retardation, and in patients with supernumerary marker chromosomes or chromosome rearrangements of chromosome 7 origin.     

Structural and sequence variants in patients with Silver‐Russell syndrome or similar features—Curation of a disease database

Silver‐Russell syndrome (SRS) is a clinically and molecularly heterogeneous disorder involving prenatal and postnatal growth retardation, and the term SRS‐like is broadly used to describe individuals with clinical features resembling SRS. The main molecular subgroups are loss of methylation of the distal imprinting control region (H19/IGF2:IG‐DMR) on 11p15.5 (50%) and maternal uniparental disomy of chromosome 7 (5%–10%). Through a comprehensive literature search, we identified 91 patients/families with various structural and small sequence variants, which were suggested as additional molecular defects leading to SRS/SRS‐like phenotypes. However, the molecular and phenotypic data of these patients were not standardized and therefore not comparable, rendering difficulties in phenotype–genotype comparisons. To overcome this challenge, we curated a disease database including (epi)genetic phenotypic data of these patients. The clinical features are scored according to the Netchine‐Harbison clinical scoring system (NH‐CSS), which has recently been accepted as standard by consensus. The structural and sequence variations are reviewed and where necessary redescribed according to recent recommendations. Our study provides a framework for both research and diagnostic purposes through facilitating a standardized comparison of (epi)genotypes with phenotypes of patients with structural/sequence variants.