The effects of biogenic and abiogenic disulphides on endothelial cells in culture: Comparison of three methods of viability assessment

Effects of biogenic and abiogenic disulfides on viability of human umbilical vein endothelial cells in culture were studied using three methods: inclusion of neutral red (NR) into cells, quantification of intracellular ATP, and modifications of the Mosmann method (1983), the essence of which consists in reduction of tetrazolim salts—MTT and MTS—by cells (Mosmann, 1983). 2,2′-Dithio-bis(N,N-diethyl)dietanamine (DS) was used as an abiogenic sulfide. As for biogenic disulfides, we used oxydized glutathione (GSSG) and garlic oil (GO), the major component of which is diallyl disulfide (DADS). It has been established that DS and GO have a compatible cytotoxic effect (ES₅₀ amounts to ～0.6 mM), whereas GSSG at a concentration up to 1 mM had no effect on the viability of endothelial cells. It has been demonstrated for the first time that DS and GO can serve as mediators of plasma-membrane oxidoreductase activity, with tetrazolium salts being used as the substrate, which may cause a false-negative effect. In this connection, Mosmann’s method has serious limitations in evaluating the effect of disulfides on cell viability, although it can be used when studying the mechanism of their action.     

三种林分生物量估算方法的比较

区域森林生物量的估算方法是人们目前关注的焦点,建立林分生物量模型成为一种趋势.本文以吉林省落叶松人工林固定样地为例,采用非线性似乎不相关回归法构建2种林分生物量模型,即基于林分变量的林分生物量模型(模型系统Ⅰ)和基于生物量换算系数的林分生物量模型(模型系统Ⅱ),给出落叶松人工林固定生物量换算系数值,并比较了3种林分生物量估算方法的预估精度.结果表明: 所建立的2种林分生物量模型中,总生物量和树干生物量模型拟合和预测效果较好,其R_a²>0.95,且均方根误差(RMSE)、平均预测误差(MPE)和平均绝对误差(MAE)都较小.树叶和树枝生物量模型拟合和预测效果相对较差,其模型的R_a²<0.95.模型系统Ⅰ和模型系统Ⅱ的预测精度均优于固定生物量换算系数法.基于生物量换算系数的林分生物量模型属于材积源生物量法,其本质与基于林分变量的林分生物量模型不同,但二者的预测效果相当.固定生物量换算系数的预测能力较差,将生物量与蓄积量之比假定为恒定常数是不恰当的.此外,为了使模型参数估计更有效,所建立的生物量模型应当考虑林分总生物量及各分项生物量的可加性.     

Comparison of three multitrait methods for QTL detection

A comparison of power and accuracy of estimation of position and QTL effects of three multitrait methods and one single trait method for QTL detection was carried out on simulated data, taking into account the mixture of full and half-sib families. One multitrait method was based on a multivariate function as the penetrance function (MV). The two other multitrait methods were based on univariate analysis of linear combination(s) (LC) of the traits. One was obtained by a principal component analysis (PCA) performed on the phenotypic data. The second was based on a discriminate analysis (DA). It calculates a LC of the traits at each position, maximising the ratio between the genetic and the residual variabilities due to the putative QTL. Due to its number of parameters, MV was less powerful and accurate than the other methods. In general, DA better detected QTL, but it had lower accuracy for the QTL effect estimation when the detection power was low, due to higher bias than the other methods. In this case, PCA was better. Otherwise, PCA was slightly less powerful and accurate than DA. Compared to the single trait method, power can be improved by 30% to 100% with multitrait methods.     

Comparison of three common DNA concentration measurement methods

Accurate measurement of DNA concentration is important for DNA-based biological applications. DNA concentration is usually determined by the ultraviolet (UV) absorption, fluorescence staining, and diphenylamine reaction methods. However, the best method for quality assurance of measurements is unknown. Here, we comprehensively compared these methods using different types of samples. We found that all three methods accurately determined the concentrations of high-purity DNA solutions. After digestion of DNA samples, concentration measurements revealed that the PicoGreen dye method was very sensitive to the degradation of DNA. The three methods displayed different anti-jamming ability when contaminants such as transfer RNA (tRNA), protein, and organic chemicals were included in DNA solutions. The diphenylamine reaction method gave the highest accuracy, with an average error of approximately 10% between measured and true values. The PicoGreen dye method was influenced by tRNA and protein, and the UV absorption method was susceptible to all kinds of impurities. Overall, the diphenylamine reaction method gave the most accurate results when DNA was mixed with contaminants, the PicoGreen dye method was most suitable for degraded DNA samples or DNA extracted from processed products, and the UV absorbance method was best for evaluating the impurities in DNA solutions.     

兔VX2肝癌模型制作技术改良

目的探讨制作兔VX2肝癌模型的新技术、新方法。方法将新西兰兔30只随机等分为3组,分别为嵌插组、改良嵌插组和经皮穿剌组。分别按不同方法建立肝癌模型,于建模后第1、2、3周分别进行CT扫描,评估肿瘤大小。3周后处死动物进行解剖,观察肝脏成瘤及转移情况,比较各组转移率,并行常规病理组织学检查。结果 30只动物建模成功28只,成功率93%,经皮穿剌组有2只肝脏未见种植灶,嵌插组和改良嵌插组全部种植成功。改良嵌插组腹壁转移率显著低于嵌插组和经皮接种组。结论改良嵌插法3周内不会形成接种部位腹壁以及远处的转移,是一种理想的移植性肝癌模型建模方法。     

猪源性成分检测中3种DNA提取方法比较

为了达到对动物源性成分快速、准确的检定,对提取动物源性基因组DNA的方法进行了比较分析。考察酚-三氯甲烷法、聚乙烯吡咯烷酮法(PVP法)和试剂盒法这3种方法对DNA提取的浓度、纯度及实时荧光PCR扩增效果的影响。结果表明:酚-三氯甲烷法提取DNA浓度最高,试剂盒法纯度最高且实时荧光PCR扩增效果最好,但PVP法操作简单、安全、经济,提取的DNA用于实时荧光PCR扩增检出限可达1.98 pg/μL。使用PVP法对市场上10份不同类型的动物性产品进行了检测,检出两份产品中含有猪源性成分。PVP法应是3种方法中的首选方法,本文为实验室选择合适的DNA提取方法提供了依据。     

Comparison of three diagnostic methods to identify subclinical endometritis in mares

The objective of this study was to compare the accuracy of a uterine swab (US), a cytological brush (CB) and an endometrial biopsy (EB) to detect subclinical endometritis in mares. Cytological and bacteriological results of all three techniques were related to histological occurrence of polymorphonuclear neutrophils (PMNs) in the stratum compactum, commonly known as ‘best standard'; to diagnose endometritis.Samples were taken from 55 mares of different breeds without clinical signs of endometritis. Samples for US, CB and EB were collected, smeared on a microscopic slide and cultured for bacterial growth. Endometrial biopsy samples were additionally stored in 4% formaldehyde for histological analysis. Bacteriological cultures and cytological samples of all techniques were classified as negative (no uterine pathogens in monoculture; < 2% PMNs) or positive (uterine pathogens in > 90% of the grown colonies; > 2% PMNs) for endometritis. Uterine pathogens were diagnosed in 20.0% of the mares. Isolation of pathogens was not associated with positive cytological findings (r = −0.23; P = 0.87). None of the six mares with an Escherichia coli infection (10.9%) showed a positive cytological result. In contrast, two of five mares infected with Streptococcus zooepidemicus had a positive cytological result.Histologically, the presence of PMNs in the stratum compactum was regarded as positive for endometritis when the mare was in diestrus at time of sampling. Compared to the ‘best standard', sensitivity for cytology of CB, US and EB was 0.17, 0.00 and 0.25, respectively. Specificity for cytology of CB, US and EB was 0.83, 0.93 and 0.85, respectively. Sensitivity of uterine culture was 0.25, 0.33 and 0.25 for CB, US and EB, respectively. Specificity for culture of CB, US and EB was 0.80, 0.83 and 0.95, respectively. In conclusion, cytological or bacteriological examinations alone provide a high incidence of false negative results. Sensitivity of cytology combined with bacteriology of CB was 0.42. A combination of a bacteriological and a cytological examination of a CB sample improved the diagnostic performance in subfertile mares. Based on these results, we can recommend the CB to improve the diagnosis of subclinical endometritis in the mare compared to the US alone as currently used routine method.     

检测聚丙烯酰胺凝胶中蛋白质的3种染色方法比较

用考马斯亮蓝染色、银染色、铜染色等 3种方法对同一种蛋白质染色的灵敏度、快速性进行比较 ,得出 3种蛋白质染色方法的优缺点 ,为蛋白质电泳染色合理选用不同方法提供依据     

Comparison of voluntary food and water consumption and digestion in Kirk's dikdik and suni

Voluntary food and water consumption of Kirk's dikdik (Madoqua kirki) and suni (Nesotragus moschatus) was determined under controlled laboratory conditions. Both species consumed large amounts of dried matter (lucerne hay leaves) per day. Dry matter consumption of dikdik accounted for 3.8 ± 0.5% and of suni for 3.5 ± 0.2% of body weight. Dry matter intake in one immature dikdik and one female dikdik during late pregnancy and lactation was considerably higher. Dikdik drank very little water (278 ml/day, equalling 83 ml/kg^0.82) which is further proof of their adaptation to arid environment. Suni drank about twice as much (401 ml/day, equalling 155 ml/kg^0.82), but individual variation of water con sumption was high. Thus, the forest-dwelling suni seems to be less adapted to de hydration than the dikdik. There was no difference in the digestibility of dry matter and gross energy of lucerne hay leaves for dikdik and suni. The fraction of N-free extracts which consists mainly of soluble carbohydrates was digested very well (84% and 81%, respectively), whereas fibre and cellulose digestibility was poor. Suni digested crude protein, minerals and cellulose significantly better than dikdik.     

Comparison of three rapid methods for identification of Salmonella spp

A study was carried out to compare three rapid methods for detection of Salmonella spp. The fluorogenic MUCAP test (Biolife, Italy), the SM-ID agar test (bioMérieux, France) and the Rambach agar test (Merck, Germany) were used in this study to examine 103 strains (69 Salmonella strains and 34 non- Salmonella strains). Two conventional culture media, Hektoen and Leifson agars, were also included. The sensitivities of the MUCAP, SM-ID, Rambach and Hektoen agar tests for pure strains were 100, 93, 88 and 99%, respectively, and their specificities were 74, 97, 76 and 59%, respectively. A total of 100 stool samples from patients with acute diarrhoea was also tested and showed great discrepancy between the different methods. In agreement with other investigators, it was found that the discriminating capacity of Rambach and SM-ID as primary plating media was very restricted. The MUCAP test was very sensitive, rapid and easy to perform but not very specific. In view of these results, it is essential to combine different methods for the accurate and reliable detection of Salmonella strains.     

Lithologic controls on biogenic silica cycling in South African savanna ecosystems

The efficacy of higher plants at mining Si from primary and secondary minerals in terrestrial ecosystems is now recognized as an important weathering mechanism. Grassland ecosystems are a particularly large reservoir of biogenic silica and are thus likely to be a key regulator of Si mobilization. Herein, we examine the effects of parent material (basaltic and granitic rocks) on the range and variability of biogenic silica pools in grass-dominated ecosystems along two precipitation gradients of Kruger National Park, South Africa. Four soil pedons and adjacent dominant plant species were characterized for biogenic silica content. Our results indicate that although soils derived from basalt had less total Si and dissolved Si than soils derived from granite, a greater proportion of the total Si was made up of biogenically derived silica. In general, plants and soils overlying basaltic versus granitic parent material stored greater quantities of biogenic silica and had longer turnover times of the biogenic silica pool in soils. Additionally, the relative abundance of biogenic silica was greater at the drier sites along the precipitation gradient regardless of parent material. These results suggest that the biogeochemical cycling of Si is strongly influenced by parent material and the hydrologic controls parent material imparts on soils. While soils derived from both basalt and granite are strongly regulated by biologic uptake, the former is a “tighter” system with less loss of Si than the latter which, although more dependent on biogenic silica dissolution, has greater losses of total Si. Lithologic discontinuities span beyond grasslands and are predicted to also influence biogenic silica cycling in other ecosystems.     

中华稻蝗血细胞染色方法的比较

通过Giemsa、Wright和Giemsa-Wright混合染色3种方法,对中华稻蝗Oxya chinensis(Thunberg)的血细胞进行了染色和血细胞的形态学观察,其结果是Giemsa染液染色时间较长,对细胞核染色效果较好,细胞质界限清晰,但对细胞质中的颗粒染色较差;Wright染液染色时间较短,对细胞核和细...     

Comparison of three methods for DNA extraction from bone remains

Extraction of amplifiable DNA is a frequent problem when working with degraded specimens like bone samples. The possibility of obtaining as much information as possible from these samples has a particular significance in many forensic investigations. The present investigation was aimed to assess the efficiency of three organic extraction methods for purifying amplifiable DNA from bone samples. The amount of nucleic acids obtained, the success rate in the amplification of DNA microsatellite (STR) markers and amelogenin by PCR, the influence of PCR inhibitors and environmental conditions, and where the samples were found before their processing in the laboratory, were all evaluated in this investigation for the three methods. Results showed that method A (a modification of FBI method for DNA extraction) performed better in producing not a higher amount but a better quality amplifiable DNA, in comparison with the other two methods evaluated. It was also demonstrated that the quality of the DNA to be amplified by PCR was influenced by the presence of inhibitors and/or contaminants and the environmental conditions where the bone sample was taken from. The worst conditions were observed from aquatic environments. The results suggest that the implementation of some specific modifications in the method A (use of purification columns, reliable quantification methods and different dilutions) would help to obtain better DNA extracts intended to be used in different molecular identification tests.     

Comparison of three molecular methods for typing Aeromonas popoffii isolates

Three typing methods, restriction fragment length polymorphism (RFLP) of the 16S-23S intergenic spacer region (ISR), PCR amplification of the enterobacterial repetitive intergenic consensus (ERIC) and of the repetitive extragenic palindromic units (REP), were evaluated for typing 26 isolates of Aeromonas popoffii from different geographical origins. When the methods were independently studied, ERIC showed the highest discriminatory power. When the methods were combined, the best combination of two methods was ERIC with REP since strains showed a tendency to cluster according to their geographical origin. However, this tendency was reinforced with the addition of ISR-RFLP. This revised version was published online in June 2006 with corrections to the Cover Date.     

粪便标本艰难梭菌三种培养方法的比较

目的 比较粪便标本中艰难梭菌三种培养方法的差异性,寻找适合临床实验室使用的艰难梭菌培养方法。方法 将健康儿童的300份粪便标本分别用快速芽孢孵育法、乙醇直接处理法、富集芽孢培养法进行培养,并对三种培养方法的差异性进行统计学比较。结果 300份粪便标本快速芽孢孵育法培养出艰难梭菌51例,检出率为17.0%;乙醇直接处理法培养出48例,检出率为16.0%;富集芽孢培养法培养出44例,检出率为14.7%。三种方法的检出率差异无统计学意义（P=0.7352,P>0.05）。结论 乙醇直接处理法、快速芽孢孵育法简单快速,适合临床实验室进行艰难梭菌的快速培养;富集芽孢培养法杂菌少,适合大量艰难梭菌培养便于结果的观察及进一步的处理。     

Comparison of three methods for identifying nonfermenting gram-negative rods.

Seventy-six strains of nonfermenting gram-negative rods were tested on the Analytab Products, Inc. (API) system and on conventional media. In addition, 51 strains were tested on the Oxi-Ferm system. When the identification results were compared, the API agreed with the conventional system on 41% of the isolates and Oxi-Ferm agreed with the conventional system on 72% of the isolates. API had the greatest difficulty in identifying Pseudomonas aeruginosa. API and Oxi-Ferm both had difficulty identifying P. cepacia. Oxi-Ferm had more individual discrepant biochemical reactions than did API when compared to the conventional media, but still maintained a higher percentage agreement with the conventional system.     

Comparison between tracheal ratio methods used by three observers at three occasions in English Bulldogs

Background

Tracheal hypoplasia is a congenital condition described in mainly brachycephalic breeds and is one component of the brachycephalic obstructive airway syndrome (BOAS). Two radiographic methods have been described to evaluate the dimensions of the tracheal diameter in dogs and to distinguish between hypoplastic and non-hypoplastic tracheas: the tracheal lumen diameter to thoracic inlet distance ratio (TD/TI) and the ratio between the thoracic tracheal luminal diameter and the width of the proximal third of the third rib (TT/3R). The purpose of this study was to compare these two published radiographic methods between observers, different measuring occasions and to investigate the effect on classification of dogs as having hypoplastic or non-hypoplastic tracheas using four previously published mean ratios as cut-offs (<0.11, <0.127 and <0.144 for the TD/TI and <2.0 for the TT/3R method).Three observers evaluated right and left lateral recumbent radiographs from 56 adult English Bulldogs independently on three different occasions. TD/TI and TT/3R ratios were calculated and correlated between measuring occasions. Kappa, observed, positive, and negative agreements were calculated between observers and measuring occasions. Number of hypoplastic and non-hypoplastic dogs for each method and occasion was determined using <0.11, <0.127 and <0.144 as cut-offs for TD/TI and <2.0 for TT/3R.

Results

Intraobserver agreement varied with kappa between 0.45-0.94 for the TD/TI and 0.20-0.86 for the TT/3R method. Interobserver kappa varied between 0.27-0.70 for the TD/TI method and between 0.05-0.57 for the TT/3R method. There was poor agreement in classifying English Bulldogs as tracheal hypoplastic or non-hypoplastic, depending on measuring method, cut-off value and observer.

Conclusions

The diagnostic value of both the TD/TI and TT/3R methods with such poor agreement is questionable, and significantly impacts their reliability for both clinical evaluation of dogs and use in health screening programs.