血清钠、钾离子的均相直接测定方法研究进展

血清钠离子和钾离子的测定在临床诊断上意义重大,其常规检测方法火焰光度法和离子选择性电极法都需要昂贵的仪器且操作复杂,因此近年来开发了一些均相直接测定方法。本文综述了近年研制出的血清中钠、钾离子的各种均相直接测定方法,评述了各种直接测定方法的优、缺点。血清中钠、钾离子进行均相直接测定有着准确度高、重复性好等优点,可在临床生化自动化分析仪上应用。     

Comprehensive Analysis of Secondary Dental Root Canal Infections: A Combination of Culture and Culture-Independent Approaches Reveals New Insights

Persistence of microorganisms or reinfections are the main reasons for failure of root canal therapy. Very few studies to date have included culture-independent methods to assess the microbiota, including non-cultivable microorganisms. The aim of this study was to combine culture methods with culture-independent cloning methods to analyze the microbial flora of root-filled teeth with periradicular lesions. Twenty-one samples from previously root-filled teeth were collected from patients with periradicular lesions. Microorganisms were cultivated, isolated and biochemically identified. In addition, ribosomal DNA of bacteria, fungi and archaea derived from the same samples was amplified and the PCR products were used to construct clone libraries. DNA of selected clones was sequenced and microbial species were identified, comparing the sequences with public databases. Microorganisms were found in 12 samples with culture-dependent and -independent methods combined. The number of bacterial species ranged from 1 to 12 in one sample. The majority of the 26 taxa belonged to the phylum Firmicutes (14 taxa), followed by Actinobacteria, Proteobacteria and Bacteroidetes. One sample was positive for fungi, and archaea could not be detected. The results obtained with both methods differed. The cloning technique detected several as-yet-uncultivated taxa. Using a combination of both methods 13 taxa were detected that had not been found in root-filled teeth so far. Enterococcus faecalis was only detected in two samples using culture methods. Combining the culture-dependent and –independent approaches revealed new candidate endodontic pathogens and a high diversity of the microbial flora in root-filled teeth with periradicular lesions. Both methods yielded differing results, emphasizing the benefit of combined methods for the detection of the actual microbial diversity in apical periodontitis.     

Methods and Errors in Measurements of Synovial Fluid Volume in Stifles with Low Volume and High Viscosity Synovial Fluid. An Experimental Study in Goats

Synovial fluid (SF) volume was calculated using various methods in the stifles of goats, in which the cranial cruciate ligament had been transected on one side. Measurements were performed prior to surgery and again 4,8, and 18 weeks following surgery, by measuring the dilution of an injected radioactive tracer diluted by the SF. Later, 7 months following surgery, SF volume measurements using simple arthrocentesis were performed on stifles in 9 of the goats, and the SF that could not be aspirated, was calculated using 2 indirect methods simultaneously on identical fluids in 3 of these goats. SF was also collected directly during staged arthrotomy of the stifles in 4 goats. There were conflicting results between methods, but the resulting calculated SF volumes seemed to be larger in the operated stifles compared to the controls for all the methods at about the same degree. The 2 indirect methods used to calculate the fluid remaining in the joints following arthrocentesis gave disparate volume calculations. The experiments revealed sources of error in all methods. Direct methods failed to acquire the total fluid volume, and indirect methods were subject to improper mixing and escape of the injected fluid or synovial fluid or both. It was concluded that none of the methods could be used to measure the “true” volume of SF, if such a concept exists and can be defined. None of the methods were considered reliable to compare volumes in different type of joints containing this type of fluid. It was, however, concluded that all the methods gave indication of increased SF volume present on a relative basis when paired joints were compared.     

Screening of different computational models for the preparation of sol–gel imprinted materials

Different computational models were used and screened to find a rational way in selecting the appropriate functional silane monomer for the best molecular imprinted xerogel (MIX) formulation. Several functional silane monomers were used and allowed to react with a template model, tetracycline (TC). The resulting template-monomer complex molecules were first optimized and their interaction energies (IEs) were calculated using different computational methods such as semi-empirical methods, ab-initio methods, density functional theory (DFT) methods and solvent model method. The formulations used for calculation were also prepared and their performance in binding with TC was determined using tritium labeled sample. Results showed that the rankings of the different formulations varied with the different computational methods. However, rankings of the IEs of the xerogels are similar to that of the imprinting factor (IF) when HF and B3LYP at SV(P) and SVP basis set levels were used. The best imprinted xerogel, allyltriethoxysilane (AtEOS) ranked first in ten out of the 26 computational models that were screened and at all computational methods at tetramer system.     

苍耳柄锈菌三裂叶豚草专化型冬孢子基因组DNA快速提取方法的比较研究

以苍耳柄锈菌三裂叶豚草专化型Puccinia xanthii f. sp. ambrosiae-trifidae为研究试材,比较研究了其冬孢子DNA提取的9种方法,其中CTAB-钢珠法、改良的微型电钻法以及EZ-Kit改良法获得的基因组DNA经检测质量较好。在此基础上,利用ITS-PCR和ISSR引物UBC#835将待用DNA进行PCR扩增检测。结果表明,上述3种方法提取的DNA适合于ISSR反应。研究结果为专性寄生锈菌分子遗传变异的研究提供了保障。     

Genetic Variance and Correlation after Selection for Two Traits by Index, Independent Culling Levels and Extreme Selection

Three two-trait selection methods were analyzed for their effects on genetic variance and correlation by multivariate methods, two-locus methods and computer simulation. The two-trait selection methods studied were independent culling levels (ICL), index (IND) and extreme (EXT) selection. The effects of the selection methods on genetic variance and correlation were partitioned into permanent effects due to changes in gene frequencies and temporary effects due to nonrandom association of alleles at different loci. Multivariate methods were used to predict temporary effects from a single generation of selection by each method and from several generations of index selection. Two-locus theory was used to determine the stability and rank of temporary effects on genetic correlation for all three methods. Predictions were compared to computer simulation results. When selection increased the means of both traits, EXT had the lowest (closest to -1.0) genetic correlation and highest variances, while ICL tended to have the highest (closest to 1.0) genetic correlation. When selection increased the mean of one trait and decreased the mean of the other, EXT had the highest genetic variances and correlation, while ICL had the lowest genetic variances and correlation.     

A Benchmark of Parametric Methods for Horizontal Transfers Detection

Horizontal gene transfer (HGT) has appeared to be of importance for prokaryotic species evolution. As a consequence numerous parametric methods, using only the information embedded in the genomes, have been designed to detect HGTs. Numerous reports of incongruencies in results of the different methods applied to the same genomes were published. The use of artificial genomes in which all HGT parameters are controlled allows testing different methods in the same conditions. The results of this benchmark concerning 16 representative parametric methods showed a great variety of efficiencies. Some methods work very poorly whatever the type of HGTs and some depend on the conditions or on the metrics used. The best methods in terms of total errors were those using tetranucleotides as criterion for the window methods or those using codon usage for gene based methods and the Kullback-Leibler divergence metric. Window methods are very sensitive but less specific and detect badly lone isolated gene. On the other hand gene based methods are often very specific but lack of sensitivity. We propose using two methods in combination to get the best of each category, a gene based one for specificity and a window based one for sensitivity.     

Light-microscopic detection of acidic glycoconjugates with sensitized diamine procedures

Summary To enhance the efficiency and specificity of diamine methods in light microscopy, these methods were sensitized by sliver enhancement in combination with trichloro(ethylene) platinate (KTP). The sensitized diamine methods consisted of a diamine (high or low iron diamine: HID or LID), KTP, borohydride reduction (BH) and a physical development (PD) sequence. The new methods have been successfully applied to routinely prepared tissue sections obtained from rat organs, such as salivary glands, stomach, colon, kidney, lung and trachea. In the tissues subjected to the sensitized diamine methods, weakly diamine-stained histological structures exhibited vivid positive reactions. The combined sensitized diamine methods and selective procedures, such as enzyme digestion and chemical modification, have substantiated that these methods were of sufficient efficiency and specificity.     

Effects of Environmental Toxicants on Metabolic Activity of Natural Microbial Communities

Two methods of measuring microbial activity were used to study the effects of toxicants on natural microbial communities. The methods were compared for suitability for toxicity testing, sensitivity, and adaptability to field applications. This study included measurements of the incorporation of ¹⁴C-labeled acetate into microbial lipids and microbial glucosidase activity. Activities were measured per unit biomass, determined as lipid phosphate. The effects of various organic and inorganic toxicants on various natural microbial communities were studied. Both methods were useful in detecting toxicity, and their comparative sensitivities varied with the system studied. In one system, the methods showed approximately the same sensitivities in testing the effects of metals, but the acetate incorporation method was more sensitive in detecting the toxicity of organic compounds. The incorporation method was used to study the effects of a point source of pollution on the microbiota of a receiving stream. Toxic doses were found to be two orders of magnitude higher in sediments than in water taken from the same site, indicating chelation or adsorption of the toxicant by the sediment. The microbiota taken from below a point source outfall was 2 to 100 times more resistant to the toxicants tested than was that taken from above the outfall. Downstream filtrates in most cases had an inhibitory effect on the natural microbiota taken from above the pollution source. The microbial methods were compared with commonly used bioassay methods, using higher organisms, and were found to be similar in ability to detect comparative toxicities of compounds, but were less sensitive than methods which use standard media because of the influences of environmental factors.     

米根霉发酵液中乳酸含量的测定方法研究

目的:为了找到方便、准确、快捷的米根霉RL6041菌株发酵液中乳酸含量的检测方法。方法:同时采用EDTA定钙法、高效液相色谱(HPLC)法和生物传感仪法三种方法测定米根霉RL6041菌株发酵液中的乳酸含量。结果:米根霉RL6041菌株三批次发酵的测试结果的差异显著性分析表明,在同一发酵批次的乳酸含量测试中,EDTA定钙法与HPLC法、生物传感仪法有显著差异(p<0.05),而HPLC法与生物传感仪法无显著性差异(p>0.05)。EDTA定钙法平均误差7.50g/L;而HPLC法和生物传感仪测定法的平均误差分别为2.84g/L和2.39g/L。结论:EDTA定钙法简便快速,但重复性差;HPLC法准确、灵敏;生物传感仪测定法比较准确和方便。     

Mechanical disruption of Escherichia coli for plasmid recovery

Five different mechanical cell disruption processes were evaluated as methods to extract plasmids from bacterial cells. The methods used were sonication, nebulization homogenization, microfluidization, and bead milling. The recovery yields of intact plasmids from the various methods were measured by quantitative gel electrophoresis. Bead milling and microfluidization were found to have the highest potential for large scale extraction with total intact recoveries of over 90% and around 50%, respectively. Other methods resulted in substantial plasmid degradation, with recoveries no greater than 20% of the total intact plasmid. (c) 1995 John Wiley & Sons, Inc.     

Antimicrobial susceptibility of Campylobacter jejuni subsp. jejuni assessed by E-test and double dilution agar method in Southern Chile

The susceptibility patterns of 108 Campylobacter jejuni subsp. jejuni clinical strains, to six antimicrobial agents was determined by using the E-test and the double dilution agar methods. Using both methods, no strain was found to be resistant to ciprofloxacin, erythromycin and gentamicin, but two (1.8%) were resistant to tetracycline and all to aztreonam. Seven (6.5%) strains were resistant to ampicillin by the E-test and five (4.6%) by the double dilution agar method and by both methods. No great discrepancies were observed between both methods.     

Vulnerability to cavitation in Olea europaea current‐year shoots: further evidence of an open‐vessel artifact associated with centrifuge and air‐injection techniques

Different methods have been devised to analyze vulnerability to cavitation of plants. Although a good agreement between them is usually found, some discrepancies have been reported when measuring samples from long‐vesseled species. The aim of this study was to evaluate possible artifacts derived from different methods and sample sizes. Current‐year shoot segments of mature olive trees (Olea europaea), a long‐vesseled species, were used to generate vulnerability curves (VCs) by bench dehydration, pressure collar and both static‐ and flow‐centrifuge methods. For the latter, two different rotors were used to test possible effects of the rotor design on the curves. Indeed, high‐resolution computed tomography (HRCT) images were used to evaluate the functional status of xylem at different water potentials. Measurements of native embolism were used to validate the methods used. The pressure collar and the two centrifugal methods showed greater vulnerability to cavitation than the dehydration method. The shift in vulnerability thresholds in centrifuge methods was more pronounced in shorter samples, supporting the open‐vessel artifact hypothesis as a higher proportion of vessels were open in short samples. The two different rotor designs used for the flow‐centrifuge method revealed similar vulnerability to cavitation. Only the bench dehydration or HRCT methods produced VCs that agreed with native levels of embolism and water potential values measured in the field.     

The reliable diagnosis for an early stage of hereditary muscular dystrophy of mice (author's transl)

The methods to find hereditary muscular dystrophy mice (dy-mice) were described. One was to observe whether or not mice dragged their hind limbs immediately after they were dropped onto a table following their suspension by their tails. The other was to observe dragging their hind limbs immediately after they were restored to a normal position from a supine one. This limbs-dragging induced by these methods were characteristic of dy-mice. Among 437 mice checked by these methods, 76 showed the drag during 14-23 days after birth (18.3 days on the average) and later they were confirmed to be dy-mice without exception. Therefore, it was concluded that these methods were useful for the accurate diagnosis of dy-mice at an early stage.     

Determination of total copper and zinc contents of Egyptian soils using three different methods

Summary To compare chemical methods for determining total contents of Cu and Zn in Egyptian soils, surface samples of two groups of soils from Egypt namely the alluvial and the calcareous were chosen. The samples were analyzed for the total Cu and Zn using three chemical methods namely, aqua regia, hydrofluoric acid and fusion methods. The mean values of total Cu determined by aqua regia, hydrofluoric acid and fusion methods were 58.7, 69.2, 69.4 ppm for the alluvial soils and 11.8, 13.0, 12.8 ppm for the calcareous soils respectively. The corresponding values of Zn were 138.6, 189.4, 189.8 ppm for the alluvial soils and 58.6, 89.7, 90.3 ppm for the calcareous soils. The Cu and Zn contents in the alluvial and calcareous soils, determined by the aqua regia method was lower as compared with those determined by the fusion or hydrofluoric methods.An attempt was made to use the etching of soil with aqua regia and the linear relationship, to quantitavely evaluate the total content of Cu and Zn determined with hydrofluoric acid or fusion methods.     

Automatic morphological sieving: comparison between different methods, application to DNA ploidy measurements.

The aim of the present study is to propose alternative automatic methods to time consuming interactive sorting of elements for DNA ploidy measurements. One archival brain tumour and two archival breast carcinoma were studied, corresponding to 7120 elements (3764 nuclei, 3356 debris and aggregates). Three automatic classification methods were tested to eliminate debris and aggregates from DNA ploidy measurements (mathematical morphology (MM), multiparametric analysis (MA) and neural network (NN)). Performances were evaluated by reference to interactive sorting. The results obtained for the three methods concerning the percentage of debris and aggregates automatically removed reach 63, 75 and 85% for MM, MA and NN methods, respectively, with false positive rates of 6, 21 and 25%. Information about DNA ploidy abnormalities were globally preserved after automatic elimination of debris and aggregates by MM and MA methods as opposed to NN method, showing that automatic classification methods can offer alternatives to tedious interactive elimination of debris and aggregates, for DNA ploidy measurements of archival tumours.     

Evaluation of the methods for enumerating coliform bacteria from water samples using precise reference standards

AIMS: To use BioBall cultures as a precise reference standard to evaluate methods for enumeration of Escherichia coli and other coliform bacteria in water samples. METHODS AND RESULTS: Eight methods were evaluated including membrane filtration, standard plate count (pour and spread plate methods), defined substrate technology methods (Colilert and Colisure), the most probable number method and the Petrifilm disposable plate method. Escherichia coli and Enterobacter aerogenes BioBall cultures containing 30 organisms each were used. All tests were performed using 10 replicates. The mean recovery of both bacteria varied with the different methods employed. CONCLUSIONS: The best and most consistent results were obtained with Petrifilm and the pour plate method. Other methods either yielded a low recovery or showed significantly high variability between replicates. SIGNIFICANCE AND IMPACT OF THE STUDY: The BioBall is a very suitable quality control tool for evaluating the efficiency of methods for bacterial enumeration in water samples.     

Analysis of multiple depth profiles in sediment cores: an application to pollen and diatom data from lakes sensitive to acidification

The methods of clustering and ordination were compared with polynomial and segmented regression methods by application to the pollen and diatom profiles from two sediment cores obtained from lakes susceptible to acid precipitation. Clustering and ordination methods have previously been used to determine zones in sediment profiles, but regression methods which summarize the changes with depth in terms of one or more smooth curves, explicitly use the depth information. Plots of running means were also used to characterize profile shapes. The latter two methods provided a clearer understanding of the changes in diatom and pollen levels in the cores. For low diatom concentrations, non-parametric methods were used to test for a change in concentration with depth. Changes in dry weight of sediment, different bases for concentration and depth, and the effect of poor represententation of an extreme group on the pH spectrum were also considered. The regression procedures were shown to provide summaries useful for comparison of different species or of the same species in different cores. Finally, a summary is given of the similarity of the patterns in the depth profiles of eight pollen types and the non-rare diatom species in one core from each of Kejimkujik and Beaverskin Lakes, respectively.     

The robustness of two phylogenetic methods: four-taxon simulations reveal a slight superiority of maximum likelihood over neighbor joining

The robustness (sensitivity to violation of assumptions) of the maximum- likelihood and neighbor-joining methods was examined using simulation. Maximum likelihood and neighbor joining were implemented with Jukes- Cantor, Kimura, and gamma models of DNA substitution. Simulations were performed in which the assumptions of the methods were violated to varying degrees on three model four-taxon trees. The performance of the methods was evaluated with respect to ability to correctly estimate the unrooted four-taxon tree. Maximum likelihood outperformed neighbor joining in 29 of the 36 cases in which the assumptions of both methods were satisfied. In 133 of 180 of the simulations in which the assumptions of the maximum-likelihood and neighbor-joining methods were violated, maximum likelihood outperformed neighbor joining. These results are consistent with a general superiority of maximum likelihood over neighbor joining under comparable conditions. They extend and clarify an earlier study that found an advantage for neighbor joining over maximum likelihood for gamma-distributed mutation rates.