杜仲胶作为根管充填材料的可行性

背景：杜仲胶具有较好的热塑性、流动性、黏结性及抗菌性,目前尚无将其用于根管充填材料的研究。 目的：比较不同含量气相纳米二氧化硅对以杜仲胶为基质复合材料力学性能的影响,以及充填根管后的效果观察。 方法：在硫酸钡(20%)及纳米羟基磷灰石(10%)质量分数恒定的情况下,分别加入不同质量分数的杜仲胶与气相纳米二氧化硅(40%与15%,45%与20%,50%与25%,55%与30%),制备4组根管填充复合材料,以纯杜仲胶作为空白对照,检测5组材料的硬度、拉伸强度及断裂伸长率。采用ObturaⅡ技术将4组复合材料与杜仲胶、古塔胶颗粒充填到新鲜拔出的前磨牙根管中,X射线片及扫描电镜观察根管充填效果。 结果与结论：随着气相纳米二氧化硅含量的增加,杜仲胶复合材料的硬度呈上升趋势,拉伸强度呈先增大后减小的趋势,断裂伸长率呈降低趋势。杜仲胶组对X射线透射,无法显示充填材料的影像,4组复合材料均具有一定的X射线阻射性,显示复合材料均充填至根管中且充填均匀,充填物内无气泡,与根管内壁接触良好,充填效果满意;扫描电镜显示,杜仲胶组材料表面指状突起最多最长,随着气相纳米二氧化硅含量的增加,4组复合材料表面的指状突起长度呈降低趋势。表明杜仲胶复合材料在热流动状态下可注入根管内达到较好的封闭效果。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

三种根管预备器械预备根管根尖碎屑推出量和根管清理能力的比较

背景：根尖碎屑推出量是评价根管预备器械预备效果的一项重要指标。研究表明,推出根尖孔的碎屑将引起根管治疗后疼痛,减少根尖区碎屑的推出可降低术后疼痛发生率。目的：比较新型镍钛器械自调节根管锉、ProTaper Next和传统镍钛器械ProTaper Universal预备人下颌单根管前磨牙的根尖碎屑推出量和根管清理能力。方法：将45颗离体人下颌单根管前磨牙随机均分为3组,分别使用新型镍钛器械自调节根管锉、ProTaper Next和ProTaper Universal进行根管预备,收集推出根尖孔碎屑,比较不同根管预备器械的根尖碎屑推出量;纵向劈开根管预备后的牙根,扫描电镜下观察比较3种器械的根管清理能力。结果与结论：ProTaper Universal组的根尖碎屑推出量显著高于ProTaper Next和自调节根管锉组(P < 0.05),ProTaper Next组和自调节根管锉组的根尖碎屑推出量比较差异无显著性意义(P > 0.05）。自调节根管锉组预备后根管壁的碎屑和玷污层去除能力优于ProTaper Next组和ProTaper Universal组(P < 0.05),ProTaper Next组和ProTaper Universal组预备后根管壁的碎屑和玷污层去除能力比较差异无显著性意义(P > 0.05)。表明新型镍钛器械自调节根管锉和ProTaper Next的根尖碎屑推出量较传统镍钛器械ProTaper Universal少,有利于减少根管治疗后疼痛的发生率;自调节根管锉预备后根管清洁度优于ProTaper Next和ProTaper Universal。中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Antimicrobial activity and tightness of a DCPD-CaO-based hydraulic calcium phosphate cement for root canal filling

Calcium hydroxide is currently used in dentistry for endodontic treatments where its main advantage is its antibacterial and anti-inflammatory activity. However, it also has some drawbacks such as pulp necrosis, slight solubility, slow and insufficient hardening, and retraction on drying. In consequence, it is used only as temporary material for root canal disinfection. By mixing calcium hydrogen phosphate dihydrate (CaHPO4 . 2H2O, also called dicalcium phosphate dihydrate, DCPD) and calcium oxide with a sodium phosphate buffer as liquid phase, we obtained a CPC with better mechanical properties than calcium hydroxide pastes. The setting reaction produced either hydroxyapatite (HA) or a mixture of HA and calcium hydroxide depending on the relative masses of DCPD and CaO in the cement powder. The presence of calcium hydroxide a priori confers antimicrobial properties to this cement which were investigated in agar plates (diffusion method) against Streptococcus mutans, Lactobacillus acidophilus, Candida albicans, Enterococcus faecalis, Staphylococcus hominis (clinical isolates), and a preparation of polymicrobial flora isolated from dental plaque. The cement samples tested were prepared at molar calcium-to-phosphate ratios (Ca/P) of 1.67 to 2.75. A pure calcium hydroxide paste was used as reference material. Clear and reproducible bacterial growth inhibition was observed for cement samples with Ca/P > or = 2 against all the microorganisms tested. With Ca/P = 2.5, this cement alkalinizes dentinal tubules and provides a fluid-tight sealing that well compares with sealing obtained using a zinc oxide-eugenol cement without gutta-percha point. DCPD-CaO-based cement is therefore a potential root canal filler.     

Biotesting of wastewater: a comparative study using the Salmonella and CHO assay systems

Means to assess the toxicity of wastewaters are essential to implementing the Federal Clean Water Act. Health risk assessment based on single chemicals is limited by the number of chemicals that can be identified and to those chemicals for which toxicity data are available. Long-term whole animal tests on large numbers of wastewater samples are not practical. In this study, two short-term tests, the Salmonella mutagenicity assay and the Chinese hamster ovary (CHO) cell assay for mutagenicity and cytotoxicity, were evaluated as potentially useful biomonitors of wastewaters. Standard assay protocols were modified to allow testing of up to 2.5 and 3.4 ml of unconcentrated water in the bacterial and mammalian cell tests, respectively. Cytotoxicity and mutagenicity were detected in some unconcentrated wastewater samples using these modifications. Data on eight wastewater samples, representing five different sites, indicated that the Salmonella test is the more sensitive indicator of mutagenic activity in those samples, whereas the CHO test is a sensitive indicator of the presence of cytotoxic components. Wastewater concentrates, prepared by adsorption onto XAD-2 and "blue cotton," were compared in the two bioassays. In a single concentrate, the two short-term tests detected distinctly different mutagens. Advantages of using the CHO-AS52 cell line instead of the CHO-K1BH4 line for detecting wastewater mutagens were indicated. This study illustrates the complementary use of multiple bioassays and concentration methods to detect and characterize toxic components in wastewater.     

Algorithms for sleep–wake identification using actigraphy: a comparative study and new results

The aim of this study was to investigate two new scoring algorithms employing artificial neural networks and decision trees for distinguishing sleep and wake states in infants using actigraphy and to validate and compare the performance of the proposed algorithms with known actigraphy scoring algorithms. The study employed previously recorded longitudinal physiological infant data set from the Collaborative Home Infant Monitoring Evaluation (CHIME) study conducted between 1994 and 1998 [ http://dccwww.bumc.bu.edu/ChimeNisp/Main_Chime.asp ; Sleep 26 (1997) 553 ] at five clinical sites around the USA. The original CHIME data set contains recordings of 1079 infants <1 year old. In our study, we used the overnight polysomnography scored data and ankle actimeter (Alice 3) raw data for 354 infants from this data set. The participants were heterogeneous and grouped into four categories: healthy term, preterm, siblings of SIDS and infants with apparent life‐threatening events (apnea of infancy). The selection of the most discriminant actigraphy features was carried out using Fisher’s discriminant analysis. Approximately 80% of all the epochs were used to train the artificial neural network and decision tree models. The models were then validated on the remaining 20% of the epochs. The use of artificial neural networks and decision trees was able to capture potentially nonlinear classification characteristics, when compared to the previously reported linear combination methods and hence showed improved performance. The quality of sleep–wake scoring was further improved by including more wake epochs in the training phase and by employing rescoring rules to remove artifacts. The large size of the database (approximately 337 000 epochs for 354 patients) provided a solid basis for determining the efficacy of actigraphy in sleep scoring. The study also suggested that artificial neural networks and decision trees could be much more routinely utilized in the context of clinical sleep search.     

A separation-free assay for the detection of mutations: combination of homogeneous time-resolved fluorescence and minisequencing

Single nucleotide primer extension reaction has been widely used in DNA testing, and several detection methods based on this core allelic discrimination have been developed. Most of the reported formats are based on a two step protocol involving first, a liquid phase extension reaction, then a physical separation process (chromatography, electrophoresis, capture on solid support, mass spectrometry). Here we describe a new strategy based on homogeneous time-resolved fluorescence (HTRF), which does not involve any separation process and which allows a simple "mix and measure" protocol. In this approach, a 5'-(europium) cryptate-labeled primer is elongated by a biotinylated dideoxynucleoside-triphosphate, followed by the addition of a streptavidin-acceptor conjugate, which gives rise to a long-life fluorescence resonance energy transfer (FRET) signal between the cryptate donor and the acceptor. We present the development of HTRF technology as applied to the diagnosis of tumor suppressor gene p53 (TP53) mutations, and its application to the analysis of genomic DNA from human tumoral samples. The sensitivity of the reported method is compared to the corresponding fluorescent polarization assay.     

A comparative study using a fluorescence-based and a direct-count assay to determine cytotoxicity in Tetrahymena pyriformis

A novel cellular cytotoxicity assay using two fluorescent dyes was developed as an alternative method to the standard direct count of viable protozoa under light microscopy. The compound calcein AM is a non-fluorescent substance that diffuses passively across intact cell membranes and is converted by intracellular esterases to the green fluorescent calcein, which is retained in viable cells. The addition of EthD-1 that binds to DNA stained nuclei of dead cells red. The experiments were carried out in order to assess viability in the freshwater ciliate Tetrahymena pyriformis after exposure to eight surfactants, two of each representing one of four ionic class (non-ionic, anionic, cationic and amphoteric), and two heavy metals, copper and zinc, at several concentrations. In earlier time exposure, less than one hour of contact with surfactants at sublethal concentrations, the fluorescent method is more sensitive and provides more accurate results than direct counting under light microscopy. In contrast, with increasing time exposure, the results obtained by the two methods were similar. Calcein was shown to be a poor viability marker in the presence of zinc and copper since the fluorescence intensity was affected by the metal presence. However, the fluorescent method offers new opportunities to use advanced techniques, such as flow cytometry, to assess cytotoxicity in protozoa.     

Rapid detection of Leishmania infantum infection in dogs: comparative study using an immunochromatographic dipstick test,enzyme-linked immunosorbent assay,and PCR

Current zoonotic visceral leishmaniasis (ZVL) control programs in Brazil include the culling of Leishmania infantum-infected reservoir dogs, a strategy that has failed to prevent a rise of canine and human ZVL cases over the past decade. One of the main reasons this strategy has failed is because of a long delay between sample collection, sample analysis, and control implementation. A rapid, sensitive, and specific diagnostic tool would be highly desirable, because it would allow control interventions to be implemented in situ. We compared an immunochromatographic dipstick test to enzyme-linked immunosorbent assay (ELISA) and PCR for detecting L. infantum infections in dogs from an area of ZVL endemicity in Brazil. The dipstick test was shown to have 61 to 75% specificity and 72 to 77% sensitivity, compared to 100% specificity for both ELISA and PCR and 71 to 88% and 51 to 64% sensitivity for ELISA and PCR, respectively. Of the field samples tested, 92 of 175 (53%), 65 of 175 (37%), and 47 of 175 (27%) were positive by dipstick, ELISA, and PCR, respectively. The positive and negative predictive values for the tested dipstick were 58 to 77% and 75%, respectively. Efforts should be made to develop a more specific dipstick test for diagnosis of leishmaniasis, because they may ultimately prove more cost-effective than currently used diagnostic tests when used in mass-screening surveys.     

Herpes simplex virus detection from genital lesions: a comparative study using antigen detection (HerpChek) and culture.

The sensitivity of a rapid enzyme immunoassay test (HerpChek Direct Herpes Simplex Virus Antigen Test [DuPont Medical Products, Wilmington, Del.]) for the detection of herpes simplex virus (HSV) antigens in patient specimens was compared with HSV culture. HerpChek positivity for HSV occurred with 179 (65%) of 275 lesion specimens, whereas culture for HSV was positive for 145 (53%) lesions (P = 0.002). HerpChek was twice as sensitive as culture for the detection of HSV in late-stage lesions and was equivalent to culture for the detection of HSV in early lesions. We conclude that HerpChek provides greater sensitivity than culture for HSV detection in late-stage genital lesions.     

Early detection of hepatitis C virus infection using a new combined antigen-antibody detection assay: potential use in HIV co-infected individuals

BACKGROUND: The aim of this study was to determine the clinical benefit of a new combined antigen-antibody immunoenzymatic assay (Monolisa HCV Ag-Ab Ultra, Biorad) in the setting of acute HCV infection in HIV infected patients. PATIENTS AND METHODS: The performance of this assay was first evaluated in 160 HIV positive samples from uninfected and chronically HCV infected patients. To assess the performance of the Ag-Ab assay in the context of acute hepatitis C, 94 stored frozen serums from 20 recently diagnosed cases were retrospectively tested for HCV-RNA and presence of anti-HCV antibodies, in parallel with the new assay. RESULTS: In HIV infected patients, the sensitivity and specificity of the Ultra assay was 100% with a strong discrimination between positive and negative samples. In HCV acutely infected patients, the Ag-Ab assay significantly reduced the seronegative period, allowing an earlier diagnosis compared to a 3rd generation ELISA in 65% of the cases. The combined assay became positive on the same bleed as the first HCV-RNA detection for 13 patients out of 20. Nevertheless, in one case, characterized by an absence of seroconversion over one year but a continuous viral replication above 1 million IU/ml, the combined assay did not improve HCV infection diagnosis. CONCLUSION: Use of this new assay as a first line screening would significantly reduce the long seronegative window period seen in HCV infection allowing earlier HCV diagnosis and rapid clinical management. However, in case of clinical acute hepatitis C, sensitive HCV-RNA detection should remain the gold standard.     

Performance of a new, rapid assay for detection of Trichomonas vaginalis

Trichomonas vaginalis infection is highly prevalent, may have serious health consequence, and is readily treatable. However, screening has been limited by currently available tests, which tend to be insensitive, expensive, or require a delay before results are reported. The XenoStrip-Tv (Xenotope Diagnostics, Inc., San Antonio, Tex.) was evaluated on vaginal swab specimens from 936 women attending sexually transmitted disease clinics in Seattle, Wash. (n = 497), and Birmingham, Ala. (n = 439). T. vaginalis prevalence by culture (InPouch; Biomed) was 8.7% in Seattle and 21.0% in Birmingham. Compared to culture, the XenoStrip assay in Seattle was 76.7% (95% confidence interval [95% CI] = 61.4 to 88.2) sensitive and 99.8% (95% CI = 98.8 to 99.9) specific, and in Birmingham it was 79.4% (95% CI = 69.6 to 87.1) sensitive and 97.1% (95% CI = 94.8 to 98.6) specific. The positive predictive values were 97.1% in Seattle and 87.9% in Birmingham; the negative predictive values were 97.8 and 94.7%, respectively. Rapid test performance did not vary by vaginal symptoms or by the presence of other vaginal or cervical syndromes or infections. The sensitivity did vary by day of culture-positive result, with a 71% decline in XenoStrip sensitivity for every additional day delay until T. vaginalis was first detected in cultures (odds ratio = 0.29, 95% CI = 0.18 to 0.49). The rapid assay was more sensitive than wet preparation microscopy (78.5% versus 72.4% [P = 0.04]) but was less specific (98.6% versus 100% [P = 0.001]). The XenoStrip rapid assay is well suited for use in settings with a moderately high prevalence of T. vaginalis infection, particularly when microscopy is not practical.     

'Aspira': a new sensitive assay for the detection of hepatitis B surface antigen.

A sensitive method for the detection of hepatitis B surface antigen (HBsAg) is described whereby the separation of specific antibody by affinity chromatography is incorporated into one of the assay reagents. HBsAg, which may be obtained from tissue culture fluids of a human hepatoma cell line, is first reacted with polystyrene beads. Unoccupied spaces on the plastic are next covered with a non-specific protein (e.g. albumin). The plastic is then reacted with either whole antiserum or an IgG fraction of anti-HBs. Care must be taken to cover all of the reacting sites of the first layer of HBsAg with sufficient anti-HBs. This results in a reagent of detecting antigen. No affinity purified antibody was necessary because the reagent, at this stage, contains only specific antibody on the surface. Antigen reacting with this reagent can be detected by the addition of radioactively labeled IgG fraction of anti-HBs, which will complete the 'sandwich'. This assay has been evaluated and found to be as sensitive as those commerically available.     

A comparative study of chemokine rantes detection using ELISA and Western blot

Chemokines in biological sample are frequently found at very low level. Further, concentrations of chemokines which were measured in the same tissue detected with different methods often differ in literature. Therefore, RANTES concentrations were quantified by application of sandwich enzyme-linked immunosorbent assay (ELISA) and Western blot analyses. The sensitivity of ELISA was found to be much higher than that of Western blot. Additionally, the detection time differed considerably as well. For biological and biochemical characterization of chemokines it is essential to implement the optimal purification and detection techniques. With an understanding of the technical procedures and some pitfalls, chemokine detection can be applied more reliably.     

Measurement of anti-DNA antibodies by ELISA: a comparative study with Crithidia and a Farr assay

One hundred and twenty six sera from 116 patients with systemic lupus erythematosus (SLE) and from 51 control patients were assayed for the presence of anti-DNA antibodies, using a commercial enzyme linked immunosorbent assay (ELISA). Fifty three sera (42%) from SLE patients were positive and a further 13 sera (10%) fell in the 'equivocal' positive range. Three control sera were positive. In a standard 14C DNA Farr assay, 67 sera (53%) from SLE patients were positive. One control serum was weakly positive. There was a good linear correlation between absorption in the ELISA and the 14C DNA binding result (r = 0.73). Results in the ELISA and Farr assays were concordant in 96 of the 126 SLE sera, and 47 of 51 control sera. Sequential sera from a further 6 patients with fluctuating clinical activity of SLE showed similar patterns of change of anti-DNA antibodies in both assays. The ELISA was more sensitive than the Crithidia luciliae immunofluorescence assay which detected 44 positive sera (35%) in the SLE group. These results suggest that this ELISA assay may be a useful alternative to the Crithidia assay or an effective screen prior to testing in the more technically difficult and time consuming Farr assay for the measurement of anti-DNA antibodies.     

A new sensitive and rapid automated fluorometric assay for detection of natural killer activity using carboxyfluorescein diacetate

An automated fluorometric assay using carboxyfluorescein diacetate (CFDA) has been applied for the sensitive and rapid detection of natural killer (NK) activity. The lysis of target cells by NK cells was quantified by measuring the amount of CFDA released into the supernatant of culture wells with the aid of an automated microfluorometer. Both sensitivity and specificity of the presented method were higher than the 51Cr release assay. Moreover, the detection of human NK activity against K562 target cells required only 2 hrs, compared to 4 hrs in the standard 51Cr release assay.     

Multicenter study of a new fully automated HBsAg screening assay with enhanced sensitivity for the detection of HBV mutants

In a multicenter study a new, fully automated Roche Diagnostics Elecsys HBsAg II screening assay with improved sensitivity to HBsAg mutant detection was compared to well-established HBsAg tests: AxSYM HBsAg V2 (Abbott), Architect HBsAg (Abbott), Advia Centaur HBsAg (Bayer) Enzygnost HBsAg 5.0 (Dade-Behring), and Vitros Eci HBsAg (Ortho). A total of 16 seroconversion panels, samples of 60 HBsAg native mutants, and 31 HBsAg recombinant mutants, dilution series of NIBSC and PEI standards, 156 HBV positive samples comprising genotypes A to G, 686 preselected HBsAg positive samples from different stages of infection, 3,593 samples from daily routine, and 6,360 unselected blood donations were tested to evaluate the analytical and clinical sensitivity, the detection of mutants, and the specificity of the new assay. Elecsys HBsAg II showed a statistically significant better sensitivity in seroconversion panels to the compared tests. Fifty-seven out of 60 native mutants and all recombinant mutants were found positive. Among 156 HBV samples with different genotypes and 696 preselected HBsAg positive samples Elecsys HBsAg II achieved a sensitivity of 100%. The lower detection limit for NIBSC standard was calculated to be 0.025 IU/ml and for the PEI standards ad and ay it was <0.001 and <0.005 U/ml, respectively. Within 2,724 daily routine specimens and 6.360 unselected blood donations Elecsys HBsAg II showed a specificity of 99.97 and 99.88%, respectively. In conclusion the new Elecsys HBsAg II shows a high sensitivity for the detection of all stages of HBV infection and HBsAg mutants paired together with a high specificity in blood donors, daily routine samples, and potentially interfering sera.     

Development and evaluation of a new PCR assay for detection of Pseudomonas aeruginosa D genotype

This report describes a new PCR-based assay for the detection of Pseudomonas aeruginosa genotype D in occupational saturation diving systems in the North Sea. This genotype has persisted in these systems for 11 years (1993-2003) and represents 18% of isolates from infections analysed during this period. The new PCR assay was based on sequences obtained after randomly amplified polymorphic DNA (RAPD)-PCR analysis of a group of isolates related to diving that had been identified previously by pulsed-field gel electrophoresis (PFGE). The primer set for the D genotype targets a gene that codes for a hypothetical class 4 protein in the P. aeruginosa PAO1 genome. A primer set able to detect P. aeruginosa at the species level was also designed, based on the 23S-5S rDNA spacer region. The two assays produced 382-bp and 192-bp amplicons, respectively. The PCR assay was evaluated by analysing 100 P. aeruginosa isolates related to diving, representing 28 PFGE genotypes, and 38 clinical and community P. aeruginosa isolates and strains from other species. The assay identified all of the genotype D isolates tested. Two additional diving-relevant genotypes (TP2 and TP27) were also identified, as well as three isolates of non-diving origin. It was concluded that the new PCR assay is a useful tool for early detection and prevention of infections with the D genotype.