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PubMed2001

Polycyclic aromatic hydrocarbon 13C/12C ratio measurement in petroleum and marine sediments application to standard reference materials and a sediment suspected of contamination from the Erika oil spill.

This paper describes a simple and rapid sample preparation procedure allowing to measure the stable carbon isotopic composition of polycyclic aromatic hydrocarbons (PAHs) in petroleum and in sediments. The aromatic fraction is first purified and isolated on alumina and silica micro-columns. A high-performance liquid chromatography fractionation allows one then to isolate each aromatic family in order to limit coelutions between PAHs. Moreover, this purification step reduces the importance of the unresolved complex mixture which otherwise contribute to the GC-isotope ratio MS background signal. The application of this analytical procedure has allowed one to determined PAH isotopic composition in a reference material crude oil (SRM 1582) and a marine sediment (SRM 1944) with good reproducibility as uncertainties between three independent assays performed were lower than 0.5 per thousand. This analytical procedure has then been successfully applied to confirm the contamination of a sediment by the petroleum product spilled by the Erika tanker after its wreck on 12 December 1999 close to the Atlantic Coast of France.

Atlantic Ocean↗
PubMed1997

Critical evaluation of the Vitek GNS F6 card results compared to standardized, reference susceptibility test methods.

A large number of Enterobacteriaceae (291 unselected and 30 clinical challenge isolates) were used to evaluate the accuracy of the Vitek GNS-F6 susceptibility testing card for 10 antimicrobial agents (ampicillin, ampicillin/sulbactam, aztreonam, ciprofloxacin, imipenem, mezlocillin, ofloxacin, piperacillin, ticarcillin, and ticarcillin/clavulanate). Results were compared to reference broth microdilution and disk diffusion methods. Highest interpretive error on initial processing were observed with ticarcillin/clavulanate (very major false-susceptible error, 3.4%), imipenem (major false-resistant error, 1.9%), and ampicillin/sulbactam (minor error, 15.9%). Repeat testing resolved many very major errors (21 of 41 results), and the overall accuracy rate was improved from 92.1 to 93.4%. Analysis of all minor interpretive errors demonstrated that the trend for Vitek was to report slightly lower MICs (6 of 10 drugs; 97 of 159 results) in comparison to the reference test results. If a heavy inoculum was used in the Vitek cards, false resistance was observed more frequently with aztreonam and penicillins. These data demonstrate that susceptibility testing accuracy with Vitek GNS-F6 card based on categorical agreement varies from 83.2% (ampicillin/sulbactam) to 99.4% (ciprofloxacin) when testing enteric bacilli. Some antimicrobial agents (beta-lactamase inhibitor/penicillin combinations, antipseudomonal penicillins) may require slight modification of interpretive software. Finally, the overall accuracy of the Vitek System was greater than 91% for 9 of 10 drugs tested with a very low, acceptable rate of false-susceptible error (0.8%).

Anti-Bacterial Agents↗
PubMed2001

Standard reference materials for thorium analysis.

Reference materials (RMs) are used in analytical measurements for several purposes--to develop and validate analytical measurements, as quality control indicators and for calibration. It is therefore essential that suitable reference materials are available. Because thorium is usually found in very acid-resistant, mineral phases, this becomes even more critical when techniques such as ICP-MS are used, which require complete sample digestion. This paper gives an overview of the reference materials that are currently available for thorium (232Th and other thorium isotopes) in various matrices, sources and indicative costs. The IAEA database is identified as a particularly useful source of information, and the website address is: http://www.iaea.org/programmes/nahunet/e4/nmrm/index.htm A brief summary of the discussion held at the '1st European Workshop on the Analysis of Thorium in Workplace Materials', regarding reference materials, is given at the end of the paper. A general need for new RMs, specifically for workplace materials, was identified as a priority.

Mass Spectrometry↗
PubMed2004

The production and evaluation of a standard reference peste des petits ruminants (PPR)-diagnostic antigen using a sonication technique.

Peste des petits ruminants (PPR) is a widely spread viral disease with limited sporadic outbreaks particularly among small ruminants. The diagnosis depends on the detection of antibodies by commercially available expensive reagents. The aim of this work was to prepare and evaluate antigen from an attenuated local PPR virus in Egypt. The virus was propagated in Vero cells, subjected to 3 cycles freeze/thaw, concentrated by dialysis and sonicated for 60 seconds at 3.5 power. The antigen was tested for sterility by re-passage several dilutions in Vero cells, and culture for aerobic/anaerobic bacteria, mycoplasma and fungi using selective media. The efficiency of the antigen was evaluated against reference antigen for reactivity using ELISA and agar gel immunodiffusion (AGID) tests. The prepared antigen proved to be completely inactivated, not contaminated and efficient for the detection of antibodies to PPR by both ELISA and AGID tests. In conclusion, the prepared antigen is reliable for serodiagnosis of PPR and can replace the expensive commercial antigenss. Local large scale production of this antigen will facilitate surveillance of the disease in Egypt.

Animals↗
PubMed1988

The Bite Mark Standard Reference Scale--ABFO No. 2.

A scale of spatial reference for bite mark photography has been developed and evaluated. The scale incorporates both linear and circular graduations to meet the diverse needs of practicing forensic odontologists in the rectification and measurement of photographically recorded bite marks. Its unique L-shaped configuration ensures accurate scaling in both the vertical and horizontal directions and facilitates the gridding of photographs to correct for distortional errors created by oblique camera angles. This paper describes the design and constructional features of the scale and offers guidelines for its effective application to bite mark photography.

Bites and Stings↗
PubMed1987

A comparative study of two microcomputer nutrient data bases with the USDA Nutrient Data Base for Standard Reference.

The results of this investigation show that when direct comparisons are made between the USDA NDB and microcomputer data bases (avoiding the confounding factors of coding judgment and the differences between older and newer USDA nutrient data), differences still can exist. N3 and FP chose to seek out alternate data when the USDA NDB provided no data for a certain nutrient. FP chose to use a large number of additional sources to supplement USDA Handbook No. 8. Although the USDA NDB was very complete for all nutrients listed except for vitamin E/total and copper, gaps are likely to continue to exist because the USDA NDB is and will be in continual revision as an increasing number of nutrients are reported for an ever-growing food supply. Therefore, in accordance with established local needs, the dietitian has the responsibility both for knowing the sources used in the microcomputer nutrient data base and for making sure that reported results are reasonable.

Computers↗
PubMed2000

Development of the standard reference plane for the Heidelberg retina tomograph.

BACKGROUND: Topometry of the optic disc is the quantitative assessment of the structure of the optic nerve head by means of three-dimensional parameters. The parameter values depend on definitions of intraocular reference planes. PURPOSE: To describe the development of intraocular reference planes in laser scanning tomography for the Heidelberg Retina Tomograph (HRT) using image intrinsic data with a fixed offset reference plane (320 microm) and to present a contour-line-based "flexible" standard reference plane ("SRP") for calculation of intrapapillary stereometric parameters taking the interindividual variability of optic disc topography into account. METHODS: Ten-degree triple images were obtained by laser scanning tomography from 99 glaucoma eyes and 180 normal eyes. The images were evaluated to assess the variability of height measurements of an optic disc border contour-line segment (6 degrees width) corresponding to the site of the papillo-macular bundle as indicated by the average optic disc surface inclination angle. RESULTS: The average optic disc surface inclination angle was -7 degrees +/- 3 degrees below the horizontal meridian (0 degrees). The 6 degrees wide contour-line segment for the SRP was chosen according to the average surface inclination angle (-10 degrees to -4 degrees). The reproducibility of the SRP-segment height measurements was 16.0+/-10.8 microm for normal eyes and 23.4+/-18.0 microm for glaucoma eyes. To ensure that the automatic reference level determination for intrapapillary parameters remained below the disc border height, we defined the SRP level at a 50 microm offset (>2 SD of average segment height reproducibility in glaucoma) added to the individual height position of the 6 degrees contour line segment. CONCLUSION: The flexible standard reference plane allows for automatic determination of intrapapillary variables once a disc border contour line is interactively defined. In contrast to a fixed offset reference plane (e.g. 320 microm below the mean retina height), the interindividual variability of optic disc topography (oblique insertion, glaucomatous surface flattening) is respected at the cost of the need for an accurate optic disc border outline.

Diagnostic Techniques, Ophthalmological↗
PubMed1990

[Hydrocortisone Acetate Reference Standard (Control 891) of National Institute of Hygienic Sciences].

The raw material of hydrocortisone acetate was examined for preparation of the "Hydrocortisone Acetate Reference Standard". Analytical results were as follows: E1%1cm (242 nm) 403; IR spectrum indicates specific absorption at 3424, 1745, 1721, 1630, and 1374 cm-1; optical rotation +164.4 degrees (in dioxane); melting point 219.5 degrees (decomposition); loss on drying 0.16%; TLC and HPLC analyses indicated one and three impurities, respectively; assay by HPLC was 99.7% against the previous Reference Standard. Based on the results, the present raw material was authorized to be the Reference Standard of the National Institute of Hygienic Sciences.

Chromatography, High Pressure Liquid↗
PubMed2003

Comparison of two reference standards in validating two field mydriatic digital photography as a method of screening for diabetic retinopathy.

AIM: To compare two reference standards when evaluating a method of screening for referable diabetic retinopathy. METHOD: Clinics at Oxford and Norwich Hospitals were used in a two centre prospective study of 239 people with diabetes receiving an ophthalmologist's examination using slit lamp biomicroscopy, seven field 35 mm stereophotography and two field mydriatic digital photography. Patients were selected from those attending clinics when the ophthalmologist and ophthalmic photographer were able to attend. The main outcome measures were the detection of referable diabetic retinopathy as defined by the Gloucestershire adaptation of the European Working Party guidelines. RESULTS: In comparison with seven field stereophotography, the ophthalmologist's examination gave a sensitivity of 87.4% (confidence interval 83.5 to 91.5), a specificity of 94.9% (91.5 to 98.3), and a kappa statistic of 0.80. Two field mydriatic digital photography gave a sensitivity of 80.2% (75.2 to 85.2), specificity of 96.2% (93.2 to 99.2), and a kappa statistic of 0.73. In comparison with the ophthalmologist's examination, two field mydriatic digital photography gave a sensitivity of 82.8% (78.0 to 87.6), specificity of 92.9% (89.6 to 96.2), and a kappa statistic of 0.76. Seven field stereo gave a sensitivity of 96.4% (94.0 to 98.8), a specificity of 82.9% (77.4 to 88.4), and a kappa statistic of 0.80. 15.3% of seven field sets, 1.5% of the two field digital photographs, and none of the ophthalmologist's examinations were ungradeable. CONCLUSION: An ophthalmologist's examination compares favourably with seven field stereophotography, and two field digital photography performs well against both reference standards.

Adult↗