Proposed Screening Method Research Articles

IN SILICO PHENOTYPIC SCREENING METHOD OF MUTANTS BASED ON STATISTICAL MODELING OF GENETICALLY MIXED SAMPLES

In comprehensive functional genomics projects, systematic analysis of phenotypes is vital. However, conventional phenotypic screening is done mainly by imprecise visual observation of qualitative traits, and, therefore, in silico screening techniques for quantitative traits are required. In this report, we propose in silico phenotypic screening method that utilizes a Gaussian mixture model for the trait distribution in the offspring of a mutagenized line and the likelihood ratio test between the estimated Gaussian mixture model and the wild-type single Gaussian model. In order to evaluate the proposed method, we performed a screening experiment using real trait data of Arabidopsis. In this experiment, the proposed screening method properly distinguished the mutant line from the wild-type line. Furthermore, we conducted power analysis of the proposed method and two conventional methods under various simulated conditions of sample size and distribution of trait frequency. The result of the power analysis confirmed the effectiveness of the proposed method compared to the conventional methods.

Improved Mass Screening of Tolerance to Iron Toxicity in Rice by Lowering Temperature of Culture Solution

ABSTRACT Breeding for tolerance to iron (Fe) toxicity in rice (Oryza sativa L.) is hindered by lack of a suitable screening technique. In the culture solution methods used to date, a major difficulty has been maintaining an excess level of iron concentration in order to reveal toxicity symptoms. Experimental results showed that this problem was solved by lowering the solution temperature to around 20°C, at which leaf discoloration in susceptible cultivars became more pronounced. At 20°C Fe uptake was increased from a threshhold content of 300 mg/kg of dry weight of shoot for toxic symptom to more than 1000mg/kg in susceptible and in tolerant cultivars. Concentrations of other related minerals in the plant tissue, i.e., potassium (K) and phosphorus (P), were not affected by the low solution temperature itself but by Fe content, which can be inferred on the basis of their response curves to the excess Fe treatment. Using the proposed screening method makes it possible to obtain reproducible results in screening a large number of plants or breeding lines.

Direct screening of olive oil samples for residual benzene hydrocarbon compounds by headspace-mass spectrometry

The applicability of the direct coupling of headspace-mass spectrometry for the expeditious and reliable screening of olive oil samples for selected volatile organic compounds (viz. benzene, toluene, ethylbenzene, xylene isomers and styrene) has been evaluated. Samples were classified as recommendable or non-recommendable for human consumption taking into account the average concentration of the target analytes in virgin olive oil. The cut-off level was fixed at a global concentration of BTEXS of 0.2 μg ml −1, and several pattern recognition techniques were used in the data treatment. The reliability of the proposed screening method was evaluated in terms of the percentage of false positives and false negatives. No false negatives were obtained, while the percentage of false positives were 5% when using CA and PCA techniques. However, SIMCA yielded the best percentage of prediction as neither false negatives nor positives were obtained. Finally, a total of 50 commercial virgin olive oil samples were analyzed and only four samples gave a BTEXS concentration over the cut-off.

ファイバーグレイティング視覚センサを用いた睡眠時呼吸障害スクリーニング方法の提案

Every conventional respiration monitoring technique requires at least one sensor to be attached to the body of the subject during measurement, thereby imposing a sense of restraint that results in aversion against measurements that would last over consecutive days. To solve this problem, we developed a respiration monitoring system for sleepers, and it uses a fiber-grating vision sensor, which is a type of active image sensor to achieve non-contact respiration monitoring. In this paper, we verified the effectiveness of the system, and proposed screening method of the sleep disordered breathing. It was shown that our system could equivalently measure the respiration with thermistor and accelerograph. And, the respiratory condition of sleepers can be grasped by our screening method in one look, and it seems to be useful for the support of the screening of sleep disordered breathing.

Screening test to detect meat adulteration through the determination of hemoglobin by cation exchange chromatography with diode array detection

A simple sample preparation procedure, consisting of an extraction step with Milli-Q water as extraction solvent for hemoglobins from meat samples, followed by a filtration step with a cellulose acetate filter, is applied. After cation exchange chromatographic separation and diode array detection, different peak patterns for extracted hemoglobins of cow, lamb or pork meat are obtained. Other heme-group containing proteins like myoglobin or cytochrome C, which could be also detected with diode array detection at 416 nm, are chromatographically separated from the hemoglobins. By the use of these characteristic peak patterns, the species of the meat can be specified permitting the qualitative assessment of meat adulteration with the proposed screening method.

Invited Commentary • Author's Response

HomeRadioGraphicsVol. 22, No. 5 PreviousNext EDUCATION EXHIBITInvited Commentary • Author's ResponseJohn P. McGahanJohn P. McGahanAuthor AffiliationsDepartment of Radiology, University of California, Davis, Medical Center, Sacramento, CaliforniaJohn P. McGahanPublished Online:Sep 1 2002https://doi.org/10.1148/radiographics.22.5.g02se171137MoreSectionsFull textPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In References 1 Achiron R, Glaser J, Gelernter I, Hegesh J, Yagek S. Extended fetal echocardiographic examination for detecting cardiac malformations in low risk pregnancies. BMJ 1992; 304:671-674. Crossref, Medline, Google Scholar2 Bromley B, Estroff JA, Sanders SP, et al. Fetal echocardiography: accuracy and limitations in a population at high and low risk for heart defects. Am J Obstet Gynecol 1992; 166:1473-1481. Crossref, Medline, Google Scholar3 Sharland GK, Allan LD. Screening for congenital heart disease prenatally: results of a 2 1/2-year study in the South East Thames Region. Br J Obstet Gynaecol 1992; 99:220-225. Crossref, Medline, Google Scholar4 Yoo SJ, Lee YH, Kim ES, et al. Three-vessel view of the fetal upper mediastinum: an easy means of detecting abnormalities of the ventricular outflow tracts and great arteries during obstetric screening. Ultrasound Obstet Gynecol 1997; 9:173-182. Crossref, Medline, Google Scholar5 Yagel S, Cohen SM, Achiron R. Examination of the fetal heart by five short-axis views: a proposed screening method for comprehensive cardiac evaluation. Ultrasound Obstet Gynecol 2001; 17:367-369. Crossref, Medline, Google Scholar6 Isaksen CV, Eik-Nes SH, Blaas HG, Tegnander E, Torp SH. Comparison of the prenatal ultrasound and postmortem findings in fetuses and infants with congenital heart defects. Ultrasound Obstet Gynecol 1999; 13:117-126. Crossref, Medline, Google ScholarArticle HistoryPublished in print: Sept 2002 FiguresReferencesRelatedDetailsRecommended Articles RSNA Education Exhibits RSNA Case Collection Vol. 22, No. 5 Metrics Altmetric Score PDF download

Quantitative approach for the screening of cyclodextrins by nuclear magnetic resonance spectroscopy in support of chiral separations in liquid chromatography and capillary electrophoresis: Enantioseparation of norgestrel with α-, β- and γ-cyclodextrins

A quantitative NMR approach is proposed for the screening of cyclodextrins with regard to their enantioselectivity as chiral mobile phase additives in column reversed-phase chromatography and capillary electrophoresis. Similarities and differences between the mechanism of enantiomeric peak-separation in NMR and HPLC and CE are interpreted. The affinity of d-norgestrel to bind to (α-, β-, γ-) cyclodextrins in aqueous solution was quantified and compared by determining the association constants from chemical shift data. The association constant of l-norgestrel was estimated from titration of the racemate. Differences between the apparent association constants of the enantiomerically pure drug and the racemate are discussed from the point of view of enantiomeric competition for the cyclodextrin. The apparent association constants and chiral selectivities determined by 1H NMR for dl-norgestrel/γ-CD system at various water–methanol ratios are correlated with the corresponding chromatographic results found in the literature. The pitfalls of previously proposed screening methods based on comparison of chemical shift differences with separation parameters are discussed.

Automated kinetics-enhanced flow-injection method for histamine in regulatory laboratories: rapid screening and suitability requirements

Scombroid poisoning continues to be a leading cause of finfish-borne illness. Histamine found in implicated fish has been traditionally used as a marker, if not the cause, of scombrotoxicity. The most accepted method for detecting histamine in fish meat requires extensive manual manipulations and sample cleanup steps. To address the need for more rapid methodology, an automated, kinetically-enhanced flow injection method for histamine has been used to screen thousands of sub-samples of various fish and seafood products. Selectivity (expressed as molar fluorescence ratios) for histamine versus histidine in the sample matrix is a function of reaction kinetics. Fine-tuning this effect is sufficient to remove the need for ion-exchange sample conditioning. This fine-tuning of reaction kinetics is easily accomplished via control of flow rates, reaction temperature, etc. Method performance is excellent, with detection and quantitation limits near 0.8 and 2.4 mg/kg, and linearity to approximately 340 mg/kg. Each sample produces a response in <1 min. The method is more rapid and more practical than other proposed screening methods including alternative chemistries, HPLC methods, and immunoassays. For widespread use in the regulatory environment, an analytical method must produce similar results in other laboratories. Success requires simplified rugged procedures, a knowledge of which specific variables are important in determining method ruggedness, and demonstration of system suitability. Consistent with the methods’ reliance on chemical kinetics, the most important factors are reaction time and temperature, and the condensation reagent concentration. These factors are not so sensitive that they limit ruggedness and practicality. A temperature change of 3°C results in a 4% change in peak height, and a 1 cm change in reactor length results in a 0.4% difference. These effects are then easily controlled using commercial instrumentation. With no sample cleanup other than extraction and crude filtration, tuna can be screened for histamine with R.S.D. of <3% ( N=5 extracts, five injections/extract). Recoveries at 50 and 100 mg/kg were 97 and 118% (each spike extracted to five replicates, five injections/extract). Agreement with histamine levels using the alternate (official) method is also very good.

Enantioselective liquid-solid extraction for screening of structurally related chiral stationary phases

An enantioselective liquid-solid batch extraction method is described for the screening of novel chiral stationary phases (CSPs) during optimization studies of chiral selectors derived form a common lead structure. Extraction enantioselectivity (α) values can be calculated from the enantiomeric excess ee-values of the selectand, which are measured in the liquid phase by enantioselective HPLC. Extraction α-values have been correlated with chromatographic α-values. The influence was studied of several experimental parameters of the assay (pHa, buffer concentration, temperature, selector/selectand and phase ratio) on the enantiomeric excess (ee) values of the selectands and the enantioselectivity of the CSPs, respectively. The derived statistically significant model has then been implemented to predict chromatographic α-values of novel CSPs. For example, an ee of 89.3% for DNB-Leu as selectand could be achieved in batch extraction for a novel synthesized but mechanistically similarly-acting CSP derived form quinine. This corresponds to a calculated extraction α-value of 17.7. Based on this αextraction a chromatographic α-value of 28.8 was predicted by the linear correlation model; the experimental HPLC α-value of 31.7 was in good agreement and demonstrated the validity of the proposed screening method. The method is particularly helpful in SO optimization studies.

Screening methods for assessment of biodegradability of chemicals in seawater—Results from a ring test

An international ring test involving 14 laboratories was organized on behalf of the Commission of the European Economic Communities (EEC) with the purpose of evaluating two proposed screening methods for assessment of biodegradability in seawater: (a) a shake flask die-away test based primarily on analysis of dissolved organic carbon and (b) a closed bottle test based on determination of dissolved oxygen. Both tests are performed with nutrient-enriched natural seawater as the test medium and with no inoculum added other than the natural seawater microflora. The test methods are seawater versions of the modified OECD screening test and the closed bottle test, respectively, adopted by the Organization for Economic Cooperation and Development (OECD) and by the EEC as tests for “ready biodegradability.” The following five chemicals were examined: sodium benzoate, aniline, diethylene glycol, pentaerythritol, and 4-nitrophenol. Sodium benzoate and aniline, which are known to be generally readily biodegradable consistently degraded in practically all tests, thus demonstrating the technical feasibility of the methods. Like in previous ring tests with freshwater screening methods variable results were obtained with the other three compounds, which is believed primarily to be due to site-specific differences between the microflora of the different seawater samples used and to some extent also to differences in the applied concentrations of test material. A positive result with the screening methods indicates that the test substance will most likely degrade relatively rapidly in seawater from the site of collection, while a negative test result does not preclude biodegradability under environmental conditions where the concentrations of chemicals are much lower than the concentrations applied for analytical reasons in screening tests. Nevertheless, the screening tests are considered useful and cost-effective tools for an initial assessment of biodegradability in marine environments.