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PubMed1999

Comparison of three methods for estimating daily individual discretionary salt intake: 24 hour recall, duplicate-portion method, and urinary lithium-labelled household salt excretion.

OBJECTIVE: To compare methods for estimating discretionary salt intake, that is, salt added during food preparation and consumption in the home. SETTING: The study was carried out in a rural Guatemalan village. SUBJECTS: Subjects were selected non-randomly, based on their willingness to cooperate. Nine mother-son dyads participated; the sons were aged 6-9 y. INTERVENTIONS: Three approaches for estimating the discretionary salt consumption were used: 24 h recall; collection of duplicate portions of salt; and urinary excretion of lithium during consumption of lithium-labelled household salt. Total salt intake was assessed from the excretion of chloride over 24 h. RESULTS: The mean discretionary salt consumption based on lithium excretion for mothers was 3.9+/-2.0 g/d (mean +/- s.d.) and for children 1.3+/-0.6 g/d. Estimates from the 24 h recalls and from the duplicate portion method were approximately twice and three times those measured with the lithium-marker technique respectively. The salt intake estimated from the recall method was associated with the lithium-marker technique for both mothers and children (Spearman correlation coefficient, 0.76 and 0.70 respectively). The mean daily coefficient of variation in consumption of discretionary salt measured by the three methods, for mothers and boys respectively, were: lithium marker, 51.7 and 43.7%; 24 h recall, 65.8 and 50.7%; and duplicate portion, 51.0 and 62.6%. CONCLUSIONS: We conclude that an interview method for estimating discretionary salt intake may be a reasonable approach for determining the relative rank-order in a population, especially among female food preparers themselves, but may grossly overestimate the actual intake of salt added during food preparation and consumption.

Adult↗

PubMed1992

Report of two co-operative trials of a gel permeation chromatographic method for the isolation of pesticide residues from oils and fats. Committee for Analytical Methods for Residues of Pesticides in Foodstuffs of the Ministry of Agriculture, Fisheries and Food.

A gel permeation chromatographic (GPC) method for the determination of pesticide residues in fats and oils was subjected to two co-operative trials. Results for organochlorine pesticides (beta-HCH, gamma-HCH, dieldrin, p,p'-DDE and heptachlor) were compared with those obtained using an alumina column clean-up method. No significant differences in the mean values were found between the two techniques using the t-test (5% significance level). Horrat values demonstrated acceptable inter- and intralaboratory precisions for both clean-up techniques. Two organophosphorus pesticides (diazinon and propetamphos) and the synthetic pyrethroid deltamethrin were also determined using the GPC method. However, these compounds were not recoverable using the alumina column method, so no comparisons between the two methods were possible.

Chromatography, Gel↗

PubMed2004

[Comparison of the optical coherence method (Zeiss IOL-Master) with two ultrasonographic biometric methods for the calculation of posterior chamber intraocular lenses after phacoemulsification as part of clinical routine].

BACKGROUND: The aim of this work was to investigate the accuracy of prediction of three different biometric methods for the calculation of posterior chamber intraocular lenses. METHODS: In 59 consecutive patients who underwent extracapsular cataract-extraction with posterior chamber intraocular lens implantation, we compared the refractive results at the first day (D1) and 6 weeks (W6) after surgery with the calculated refraction of three biometric methods: the Carl Zeiss "IOL-Master 99" (IOLM), the Biovision "Echograph Class 1 - Type B" (BIOV) and the Allergan Humphrey "Ultrasonic Biometer Mod. 820" (AHUB). For statistical calculation box-plots, the Wilcoxon signed-rank test and linear regression analysis were used. RESULTS: In all patients the mean of the postoperative refraction was - 0.07 D (SD: 1.41) at day 1 and 0.12 D (SD: 1.18) at week 6. Compared to the postoperative refraction at week 6, the calculated refractive values were higher in all three measuring devices: IOLM: + 0.28 D (SD: 0.67), BIOV: + 0.60 D (SD: 0.88), AHUB: + 0.26 D (SD: 0.92). There were no statistically significant differences between IOLM and BIOV, or respectively, AHUB and BIOV (p < 0.0001), but a significant difference was found between IOLM and AHUB, (p = 0.906). To adjust for systematic differences of the agreement, one can calculate the postoperative refraction at week 6 (REF6) from IOLM by using the linear regression formula: REF6 = 1.1 x IOLM + 0.3. CONCLUSION: A comparison between the three biometric methods and the refractive results at day 1 and week 6 after cataract surgery with implantation of a posterior chamber intraocular lens showed that the calculated mean values obtained from the three biometric methods are higher than the real postoperative refraction. Calculations using the Zeiss IOL-Master and the Allergan Humphrey Ultrasonic Biometer are closer to the patient's postoperative refraction than calculations using the Biovision Echograph.

Aged↗

PubMed1980

[Study on the determination of IgA, IgG, IgM, a1-antitrypsin, haptoglobin and transferrin with the kinetic nephelometric method. Comparison with the radial immunodiffusion method (author's transl)].

The concentration of IgA, IgG, IgM, a1-antitrypsin, haptoglobin and transferrin was determined by the kinetic nephelometric method (Beckman immunochemistry analyzer) and by the radial immunodiffusion method (Behring partigen immunodiffusion plates). The investigation was carried out in 151 normal and pathological sera. The results obtained with the radial immunodiffusion method were for IgA, IgG and IgM in middle about 15%, for a1-antitrypsin about 50% and for haptoglobin about 80% higher as compared to the results determined with the kinetic nephelometric method. An acceptable correspondence between the two methods was found for the results of transferrin.

Haptoglobins↗

PubMed2006

Spectral convergence of the quadrature discretization method in the solution of the Schrodinger and Fokker-Planck equations: comparison with sinc methods.

Spectral methods based on nonclassical polynomials and Fourier basis functions or sinc interpolation techniques are compared for several eigenvalue problems for the Fokker-Planck and Schrodinger equations. A very rapid spectral convergence of the eigenvalues versus the number of quadrature points is obtained with the quadrature discretization method (QDM) and the appropriate choice of the weight function. The QDM is a pseudospectral method and the rate of convergence is compared with the sinc method reported by Wei [J. Chem. Phys., 110, 8930 (1999)]. In general, sinc methods based on Fourier basis functions with a uniform grid provide a much slower convergence. The paper considers Fokker-Planck equations (and analogous Schrodinger equations) for the thermalization of electrons in atomic moderators and for a quartic potential employed to model chemical reactions. The solution of the Schrodinger equation for the vibrational states of I2 with a Morse potential is also considered.

Journal Article↗

PubMed2002

Further reliability analysis of the Harrison radiographic line-drawing methods: crossed ICCs for lateral posterior tangents and modified Risser-Ferguson method on AP views.

OBJECTIVE: To determine whether the newly derived interclass and intraclass correlation coefficients (ICCs)would overstate or understate the results from 2 previously published studies, which used better known ICCs that assume nested factors, and to determine mean absolute differences of observers' measurements for 3 previous studies. STUDY DESIGN: Retrospective analysis of data from 2 blind studies with repeated-measure design. Two newly derived ICCs, appropriate to situations with 3 random factors (patients, examiners, and occasions) that bear a crossed (as opposed to nested) interrelationship, were applied to data from an experiment with random crossed factors. MAIN OUTCOME MEASURES: Observer reliability is determined with ICCs, 95% CIs, and observer error analysis (mean absolute differences of observers' measurements) for angles and distances derived from Harrison's modified Risser-Ferguson line-drawing method on anteroposterior (AP) lumbar and AP cervical radiographic views. Observer error analysis for angles and distances derived from Harrison's posterior tangent method on lateral cervical views was also determined. RESULTS: The majority of ICCs for reliability of line drawing on both AP cervical and AP lumbar radiographs were in the high range; 13 of 16 ICCs were greater than 0.88. The other 3 ICC values (0.61, 0.76, 0.78) concerned determining the sacral base on AP lumbar views. The new ICCs underestimated observer reliability compared with previously published results (intraclass ICCs lower by 0.01-0.02 and interclass ICCs lower by 0.03-0.10). For an error analysis on data from both AP views, the mean absolute differences of observers' measurements were 1.1 degrees to 1.8 degrees for angles and 1.2 mm to 2.3 mm for distances. For the lateral cervical analysis, the observer error was in the interval 0.8 degrees to 3.2 degrees for angles and <1 mm for distances. CONCLUSIONS: The ICCs assuming random crossed factors understate reliability compared with previously published ICC results assuming nested factors. Reliability of the Harrison modified Risser-Ferguson method of line-drawing analysis on AP views is in the high range, with the majority of ICCs >0.88. For both the Harrison modified Risser-Ferguson method on AP views and posterior tangent method on lateral cervical views, the mean absolute differences of observers' measurements are small.

Cervical Vertebrae↗

PubMed2006

Population density methods for stochastic neurons with realistic synaptic kinetics: firing rate dynamics and fast computational methods.

An outstanding problem in computational neuroscience is how to use population density function (PDF) methods to model neural networks with realistic synaptic kinetics in a computationally efficient manner. We explore an application of two-dimensional (2-D) PDF methods to simulating electrical activity in networks of excitatory integrate-and-fire neurons. We formulate a pair of coupled partial differential-integral equations describing the evolution of PDFs for neurons in non-refractory and refractory pools. The population firing rate is given by the total flux of probability across the threshold voltage. We use an operator-splitting method to reduce computation time. We report on speed and accuracy of PDF results and compare them to those from direct, Monte-Carlo simulations. We compute temporal frequency response functions for the transduction from the rate of postsynaptic input to population firing rate, and examine its dependence on background synaptic input rate. The behaviors in the1-D and 2-D cases--corresponding to instantaneous and non-instantaneous synaptic kinetics, respectively--differ markedly from those for a somewhat different transduction: from injected current input to population firing rate output (Brunel et al. 2001; Fourcaud & Brunel 2002). We extend our method by adding inhibitory input, consider a 3-D to 2-D dimension reduction method, demonstrate its limitations, and suggest directions for future study.

Action Potentials↗

PubMed1984

An evaluation of the precision and accuracy of the direct transfer method for the analysis of asbestos fibers with comparison to the NIOSH method.

Transmission electron microscopy (TEM) of asbestos on polycarbonate membrane filters prepared using the direct transfer (DT) method is used as a reference for determining the precision and accuracy of phase contrast microscopy (PCM) of the same filters and for determining the correlation between DT-PCM and the NIOSH method of asbestos analysis. Replicate aliquots of an aqueous suspension of chrysotile were filtered through either polycarbonate or cellulosic membrane filters. The polycarbonate filters were prepared using the DT method and analyzed using TEM and PCM; the cellulosic filters were treated and analyzed using the NIOSH method. Compared to the results of the TEM examination of the polycarbonate filters, about 50% of the fibers longer than 5 micron were detected using DT-PCM, which was more than 3 times the result obtained using the NIOSH method. The improvement in accuracy using DT-PCM is attributed to the increased visibility of thin fibers (diameters less than 0.1 micron). The largest variation in results was found to be due to the fiber distribution on the filters. This factor may be eliminated from interlaboratory comparisons, etc. by the use of pre-designated and well-defined fields-of-view.

Asbestos↗

PubMed1987

Development of a sampling and analytical method for measuring the epoxy content of aerosols: I. Development of the analytical method.

A method has been developed for determining the quantity of the epoxide functional group in pure epoxy resins, resins in partially-cured mixtures with amine curing agents, and commercial epoxy surface coatings. The method is based upon the reaction of the epoxide group with bromide in the presence of acid, with measurement of excess bromide in the reaction mixture by normal pulse polarography. The method extends the range of previously reported methods for epoxy analysis to samples containing 1 to 100 microequivalents (microeq) of epoxide functionality, while maintaining good precision and accuracy (coefficient of variation less than 0.06; accuracy within 2% of expected). The method has been developed for application to analysis of the epoxy content of environmental aerosols such as those of epoxy paint sprays.

Aerosols↗

PubMed1987

Development of a sampling and analytical method for measuring the epoxy content of aerosols: II. Application of the method to epoxy-containing aerosols.

Aerosols generated by epoxy spray painting consist of droplets containing partially-cured mixtures of epoxy resins and curing agents, as well as pigments, solvents and diluents. A sampling and analytical method has been developed to measure the epoxy content of these aerosols. The method collects the aerosol in a midget impinger containing dimethyl formamide, which inhibits the curing reaction between the epoxy and curing agent, preserving the unreacted epoxy functional groups present in the aerosol. The impinger contents are analyzed by reacting the epoxy with an excess of bromide generated in situ from tetraethylammonium bromide, and measuring the unreacted bromide in the reaction mixture by normal pulse polarography. The precision and accuracy of the method have been evaluated using a pure epoxy resin as a model compound. The method was applied to aerosols containing mixtures of epoxy resin and amine curing agents in various degrees of cure, to aerosols containing large quantities of nonepoxy compounds, and to aerosols of epoxy surface coatings. The method is capable of precise and accurate measurement of epoxide functionality, and it applicable to the measurement of epoxy-containing aerosols in spray finishing operations.

Aerosols↗

PubMed1988

Chemical protective clothing standard test method development: Part II. Degradation test method.

A "round-robin" interlaboratory evaluation of a proposed American Society for Testing and Materials (ASTM) standard test method was conducted for measuring the resistance of chemical protective clothing materials to degradation by liquid chemicals. The objective of this project was to determine the relative precision of the method and, where appropriate, recommend modifications that would improve reliability. In the round-robin format, eight laboratories used the proposed method to test each of five protective clothing materials against five liquid chemicals that are widely used commercially. The resulting data revealed that the proposed test method was not stringent enough to generate acceptable levels of accuracy and precision. Both intra- and interlaboratory standard deviations showed a high degree of variability in changes for the three physical properties evaluated. Changes in the method were identified which, if implemented, should improve accuracy and precision considerably.

Butanones↗

PubMed2002

Development of a novel method of female sterilization: I. The development of a novel method of hysteroscopic sterilization.

BACKGROUND AND OBJECTIVES: For more than 100 years, gynecologists have attempted to effect sterilization via a transuterine approach. Our aim was to develop a safe, simple, rapid method of sterilization that could be performed in the outpatient clinic. The authors felt that a tubal screw based on a "self-tapping" screw would be less likely to become dislodged from the uterine cornu with time because multiple backward-pointing threads prevent it from being displaced. METHODS: During the development of the technique, many changes had to be made to deliver the tubal screw effectively to the uterine cornu. These involved overcoming problems of poor cornual distension before screw application, effecting the requisite deflection toward the uterine cornu, performing the screwing action with a deflected applicator, and finally disimpacting the screw. Changes were made to the tubal screw, hysteroscope, method of uterine distension, method of deflection, screw applicator, and method of disimpaction. RESULTS AND CONCLUSIONS: The system that appears to be the most efficient consists of a 25F cystoscope with a variable bridge, a 4-mm 30-degree endoscope, and an unsealed spring applicator with bayonet mounting on the screw applied with the use of a pressure bag for uterine distension with saline solution.

Female↗

PubMed1980

Susceptibility testing with anaerobic blood culture isolates. Comparison of a rapid, direct methods with standardized method.

The results of a direct anaerobic susceptibility testing method were compared with those of a standardized method. Seventy-three blood culture isolates and eight antimicrobial agents were used. The results of the direct and standardized testing methods were within one two-fold dilution for 95.2% of the 584 anaerobe-antibiotic combinations tested. The direct susceptibility testing method is accurate and potentially valuable because the results are available more rapidly than those of the standardized testing method.

Bacteria↗

PubMed2005

A rapid LC-MS-MS method for the determination of nicotine and cotinine in serum and saliva samples from smokers: validation and comparison with a radioimmunoassay method.

The development and validation of a rapid liquid chromatography (LC)-tandem mass spectrometry (MS-MS) method for determination of nicotine and cotinine in smokers' serum is described. The method is based on solid-phase extraction in a 96-well plate format and requires only 100 microL of serum. Using normal-phase chromatography, both analytes elute in less than 1 min, which permits high sample throughput applications. The calibrated range is 2-100 ng/mL nicotine and 20-1,000 ng/mL cotinine. For known samples, recovery is 95-116% for nicotine and 93-94% for cotinine. The method is extended to rat serum and human saliva (cotinine only) using partial validation techniques. When compared with an existing radioimmunoassay method in our laboratory, the LC-MS-MS method gives improved accuracy, precision, and sample throughput.

Animals↗

PubMed1998

Comparison of the modified Stokes' method of susceptibility testing with results obtained using MIC methods and British Society of Antimicrobial Chemotherapy breakpoints.

The majority of clinical microbiology laboratories in the UK use comparative disc diffusion methods based on the Stokes' method to determine antibiotic susceptibility. The technical validity of the results obtained from the modified Stokes' method of disc testing and how they relate to MIC data are not known. We studied susceptibility testing using a modified Stokes' disc diffusion method for a wide range of clinical isolates against which MICs had been determined by collaborators not involved with the disc testing evaluation. Results indicated that for 1301 organism-antibiotic combinations the number of major errors (where resistant strains were reported as sensitive) was 21/468 (4.4%) and the number of minor errors (where sensitive strains were reported as resistant) was 14/713 (1.9%) using ciprofloxacin breakpoints of 0.5 and 2 mg/L. There was good correlation between the disc susceptibility test and the MIC for 119 isolates of Enterobacteriaceae tested with the exception of Serratia spp. Excluding Serratia spp. the number of major errors for Enterobacteriaceae was 1/200 (0.5%). Data revealed 2/25 (8%) major errors for Pseudomonas aeruginosa and 1/45 (2.2%) for Acinetobacter spp. Haemophilus influenzae showed a number of unexpected categorization errors. The modified Stokes' method performed accurately for Staphylococcus aureus and coagulase-negative staphylococci when tested for susceptibility to gentamicin, erythromycin, teicoplanin and vancomycin. No major errors were reported for Streptococcus pneumoniae and beta-haemolytic streptococci. Problems occurred with the detection of antibiotic resistance in Enterococcus spp. Major errors were seen for ampicillin (2/12 strains), teicoplanin (5/6 strains) and vancomycin (5/13 strains) using a 30 microg disc but only 1/13 strains using a 5 microg disc. Overall, from our data, the modified Stokes' disc diffusion antibiotic susceptibility test showed an unacceptable number of major errors but an acceptable number of minor errors.

Anti-Bacterial Agents↗

PubMed1998

Comparison of a new commercial colorimetric microdilution method with a standard method for in-vitro susceptibility testing of Candida spp. and Cryptococcus neoformans.

The Sensititre Yeast One method (AccuMed International Ltd, East Grinstead, UK) is a microplate-based procedure that incorporates an oxidation-reduction indicator, Alamar Blue, for the in-vitro testing of five antifungal agents (amphotericin B, fluconazole, itraconazole, ketoconazole and flucytosine). We compared this colorimetric method with a standard broth microdilution test, performed according to US National Committee for Clinical Laboratory Standards document M27-A guidelines, for determining the in-vitro susceptibilities of 180 isolates of Candida spp. (50 Candida albicans, 50 Candida glabrata, ten Candida kefyr, 20 Candida krusei, ten Candida lusitaniae, 20 Candida parapsilosis and 20 Candida tropicalis) and 20 isolates of Cryptococcus neoformans. The overall agreement between the results of the two methods (colorimetric MICs within +/- two log2 dilutions of standard MICs) were 99% for amphotericin B, 96.5% for flucytosine, 93% for itraconazole, 91.5% for fluconazole and 85.5% for ketoconazole. The overall levels of agreement between the two methods were > or = 94% for six of the eight species tested, the exceptions being C. neoformans and C. tropicalis where the overall agreement was 89% and 80% respectively. The poorest agreement between the results for individual agents was seen with C. tropicalis and the three azole agents (60-75% of colorimetric MICs within +/- two log2 dilutions of standard MICs), and C. neoformans for ketoconazole (50%). The Yeast One method appears to be a suitable alternative procedure for routine antifungal susceptibility testing of Candida spp. and C. neoformans.

Antifungal Agents↗

PubMed1978

Properties of serum lipase in patients with various pancreatic diseases. Analysis by a new serum lipase assay method (the BALB-DTNB method) in combination with gel-filtration and iso-electrofocusing techniques.

Very low levels of lipase can easily be measured by a new serum lipase assay method (the BALB-DTNB method), using BAL-tributyrate (BALB) as a substrate, 5,5'-dithiobis(2-nitrobenzoic acid) as a chromogenic SH reagent, phenylmethylsulfonylfluoride as an inhibitor of esterases and sodium dodecyl sulfate as a surfactant. The BALB-DTNB method has a higher sensitivity than the conventional serum lipase assay methods, and proved useful for analyzing the properties of serum lipases in combination with gel-filtration on a Sephacryl S 200 column and isoelectrofocusing in an Ampholine column. Serum samples containing high levels of lipases from patients with pancreatic diseases or patients in whom the pancreatic exocrine gland had been stimulated by injecting caerulein and secretin were analyzed by these methods. The lipolytic profiles obtained indicated the presence of a lipase with an estimated molecular weight of 46,000 and isoelectric points of 7.4, 6.8, or/and 6.4. A lipase with properties similar to those of the serum lipase was found to be present in human pancreatic juice.

Chromatography, Gel↗

PubMed1992

A method with three triangular flaps as a secondary operative procedure after reconstruction of the lower lip by Estlander's method.

We have devised a new method for secondary commissuroplasty after reconstruction of the lower lip using Estlander's method with both aesthetically and functionally satisfactory results. This method consists of forming two equilaterally triangular mucosal flaps on the vermilion and a small triangular skin flap in the new position of the commissure and transposing these three flaps to reconstruct the commissure. In the present paper, we reported the procedure and the results. This method produces extremely good results, obtaining favorable commissure form and reconstruction of the mucosa of both upper and lower lips without leaving an unnatural-looking color change in the mucosa or a step deformity in the vermilion. It can be expected that our method will improve the results of Estlander's operations after tumor resection in the lower lip.

Aged↗