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PubMed1984

Urinary excretion of histamine, methylhistamine (1-MeHi) and methylimidazoleacetic acid (MeImAA) in mastocytosis: comparison of new HPLC methods with other present methods.

New HPLC-methods for the determination of histamine, 1- MeHi and MeImAA in human urine were compared with methods presently at use in our laboratory, the enzymatic double-isotope assay for histamine, the DNFB-method for 1- MeHi and the semiquantitative estimation of MeImAA by thin layer chromatography (TLC). A fairly good agreement between the methods was obtained for the measurement of histamine and 1- MeHi , although there was a rather large random error probably due to poor precision of the present methods. The TLC-method for MeImAA used so far overestimated by about 20% the HPLC-values, probably due to inaccurate correction for recovery by the internal standard technique. There was found to be a strong correlation between the urinary excretion of 1- MeHi and MeImAA in mastocytosis patients and the molar ratio MeImAA /1- MeHi appeared significantly higher compared to normal controls and patients with chronic granulocytic leukemia indicating in general a more efficient histamine catabolism in mastocytosis.

Adult↗

PubMed1980

Determination of free and esterified cholesterol by a kinetic method. II. Evaluation of the enzymic method which uses 2,2-azino-di(3-ethyl-benzthiazoline-6-sulfonate) (ABTS) as chromogen.

A simple kinetic method for the determination of free and esterified serum cholesterol based on the oxidation of 2,2'-azino-di(3-ethyl-benzthiazoline-6-sulfonate) (ABTS) by use of choilesterol esterase, cholesterol oxidase and peroxidase has already been reported. Here the method is statistically examined. The method is very sensitive and precise (C.V. below 5%). The standard curve is linear up to 25.9 mmol/l. Comparison with results by Abell's method gave a linear regression of Yx = 0.2025 + 1.0043X with a correlation coefficient (r) of 0.983. Comparison with the enzymic methods of Roeschlau et al., Trinder, and Allain et al. gave Yx = 0.2037 + 0.9549X (r = 0.975), Yx = 0.4777 +0.8857X (r = 0.958) and Yx = 0.244 + 0.932X (r = 0.970), respectively. The effects of haemoglobin and bilirubin were studied and normal ranges for the method were determined on 150 healthy mature subjects of both sexes between 20 and 45 years of age. They are 3.375 to 6.948 mmol/l for total cholesterol, and 0.7196 to 2.089 mmol/l for free cholesterol.

Adult↗

PubMed1992

A non-organic and non-enzymatic extraction method gives higher yields of genomic DNA from whole-blood samples than do nine other methods tested.

We compared ten methods for extraction of DNA from whole blood. Nine methods require incubation with either enzymes or treatment of organic solvents or both. The 'Rapid Method' (RM) (Method 10) avoids the use of organic solvents (phenol/chloroform) and eliminates completely the use of proteinase K. Thus, the time and cost of DNA extraction are reduced significantly. This is accomplished by salting out and precipitation of the cellular proteins in saturated sodium chloride. This method takes less than an hour to completion, without compromising the yield or the quality of DNA. Using RM, we can make DNA from 0.1 ml of whole blood and as little as 0.5 ml of blood yields DNA sufficient to run a few Southern blots. The RM can also be applied to packed cells. The DNA is free of RNA, protein and degrading enzymes. The uncut DNA runs as a typical slow-migrating, high-molecular-weight and undegraded species in an agarose gel. The DNA is suitable for digestion by various restriction endonucleases. This procedure works equally well with fresh blood samples and with those that are stored at 4 degrees C and -70 degrees C. To our knowledge the RM reported here is the safest, fastest and most quantitative and economical method for preparation of DNA from whole blood and cells.

Chemistry Techniques, Analytical↗

PubMed1992

A method for computer simulation of ultrasound Doppler color flow images--I. Theory and numerical method.

Ultrasound imaging systems utilizing the pulsed Doppler principle are capable of providing images of blood flow in real time. We present a useful method for simulating flow images on a computer. Our method assumes that blood and surrounding tissue consist of many point-like scatters positioned randomly in three dimensions. The position-dependent acoustic response of each scatterer is calculated using the acoustic impulse response method. This method takes into account the spatial effects of the transducer geometry on both the amplitude and temporal response of point-scattering. Details of theory, assumptions made in the simulation, and numerical methods are described fully for a spherically focused transducer, as well as a discussion of signal processing for generation of the flow image. Motion of a single scatterer is investigated to test the performance of the simulation algorithm. This simulation method could potentially be beneficial for detailed study of current and future flow imaging systems.

Blood Flow Velocity↗

PubMed1991

The reliability and stability of a quantity-frequency method and a diary method of measuring alcohol consumption.

The study aimed to assess the test-retest reliability of two commonly used measures of alcohol consumption, the quantity-frequency (QF) method and the diary method, as well as the stability of scores on the two measures over time. Two methods of assessing reliability and stability were employed. The first was a traditional method based on calculation of correlation coefficients for agreement between scores on repeated measures over a short retest interval to yield test-retest reliability coefficients, and over a long retest interval to yield stability coefficients. The second method was that devised by Wiley and Wiley (1970) to differentiate the effects of reliability and stability on repeated measures over time. The two methods were applied to a sample of heavy drinkers and to a sample of light drinkers. The results indicated that both the QF and diary measures are reliable in measuring alcohol consumption of light drinkers. Both measures are less reliable for heavy drinkers. The results indicate, in addition, that drinking consumption levels of light drinkers demonstrate a high degree of stability. However, the consumption levels of heavy drinkers demonstrate less stability, especially over a long time period. Heavy drinkers significantly reduced reported levels of alcohol consumption on both measures after the first test, suggesting a regression to the mean effect or the possibility of unintended intervention effects due to repeated measurement of drinking behaviour.

Adult↗

PubMed1980

Two nephelometric methods compared with a radial immunodiffusion method for the measurement of IgG, IgA and IgM.

1. The IgG, IgA and IgM concentrations of a group of 100 or more human sera found by both the rate nephelometric Beckman Immunochemistry System and the endpoint Behring Laser Nephelometer procedure gave good correlations when compared to results obtained by an endpoint radial immunodiffusion method. The correlation coefficients for the Behring method comparisons were 0.958 for IgG, 0.979 for IgA and 0.966 for IgM when only values under 850 IU of IgM/ml were considered. The Beckman system gave correlation coefficients of 0.984 for IgG, 0.993 for IgA and 0.986 for IgM when IgM concentrations were under 500 IU/ml. Determinations from all three methods agreed well except for very high IgM values which were considerably higher by RID. 2. Both nephelometric methods are fast and precise. The average within-run coefficients of variation were 2.6% for the Behring method, 2.2% for the Beckman system and 2.1% for radial immunodiffusion while average between-run precision values of 6.9% for the Behring method, 3.7% for the Beckman system and 4.9% for radial immunodiffusion were found. The Beckman rate system has the advantage of one point calibration, ease of data processing and elimination of sample blanks.

Densitometry↗

PubMedDate not supplied

[Determination of bilirubin in capillary plasma by a direct photometric method (DPM, bilirubinometer) and the chemical determination of bilirubin in the bilirubin determination (2,5-dichlorophenyldiazonium method) in serum of venous blood samples].

The determination of bilirubin in serum was performed by the 2.5-dichlorphenyldiazonium method (DPD) and in capillary plasma by the direct photometric method (DPM). Both methods showed a good precision and accuracy. The investigation was carried out in 135 samples with a bilirubin concentration up to 25 mg/dl. The comparison of the two methods in 62 samples with a bilirubin concentration up to 10 mg/dl showed a correlation coefficient of r = 0.862 and in 73 samples with a bilirubin concentration between 10 and 25 mg/dl a correlation coefficient of r = 0.893. In 29 cases (21.5%) we found differences between the two methods of 1.5-4.0 mg/dl. Most of them were in the critical higher range. Discussion of the DPD and DPM methods.

Bilirubin↗

PubMedDate not supplied

Cyanide assay: statistical comparison of a new gas chromatographic calibration method versus the classical spectrophotometric method.

This work compares two different methods for assaying hydrogen cyanide, a spectrophotometric method and a headspace gas chromatographic method, each with its own reference standard generation. In the first method, the reference standards are cyanide solutions. In the second method, the reference standards are based upon the in situ reduction of ethyl thiocyanate by dithiothreitol to produce hydrogen cyanide. Furthermore, hydrogen cyanide concentration in the blood of patients who were poisoned by smoke inhalation or who committed suicide by cyanide ingestion is determined using both methods. Results are discussed using statistical comparison.

Calibration↗

PubMed1981

A method for the dissection of lymph node specimens (anatomic method).

A method called the "anatomic method" of dissecting lymph nodes in a variety of cancer specimens, is presented. It is found to be comparable to the clearing method in terms of detecting lymph nodes and is unencumbered by the slow turnaround time and economic inconvenience. The anatomic method is described in four steps, illustrated by a schematization of the technique. Its advantages over the clearing method include: 1) it is time saving; 2) it is conducted on the fresh state specimen; 3) it is economical; 4) it reduces the monotony often associated with such dissections; 5) it serves as a teaching exercise. Adoption of the method by pathologists is recommended.

Dissection↗

PubMed1988

Agreement among physician assessment methods. Searching for the truth among fallible methods.

To determine the convergent validity of four methods of physician assessment--physician interview, patient interview, chart audit, and videotaped observation--these methods were compared for their ability to detect medication regimens prescribed for patients with chronic obstructive pulmonary disease (COPD). Comparisons of data from the four methods revealed substantial discrepancies among them. In fact, the methods were in full accord only 36% of the time in detecting theophylline prescription, and even less often for the other COPD medications. According to physician interview, 78% of patients were on theophylline; chart audit revealed 62% of patients were on the medication; videotaped observation, 69%; and only 59% of patients reported themselves to be on theophylline. An iterative analysis, applied to determine which method most accurately captures data, revealed that reports from physician interviews were the most precise source of data. Although the order of merit was much the same for each of the drugs studied, there were some differences in levels of sensitivity across drugs. Specificities were consistently high for all drugs and all methods.

Adrenal Cortex Hormones↗

PubMed1983

Fibrinogen: a comparison of an immunoturbidimetric method with four conventional methods.

A rapid and simple immunochemical method for fibrinogen determination is described. The method is based on measuring the turbidity caused by antigen-antibody complexes with an enzyme analyser using diluted antiserum as a starting reagent. This immunoturbidimetric method correlates well with the immunodiffusion method and with two of the thrombin methods. Its correlation with the precipitation method according to Low was a little weaker.

Fibrinogen↗

PubMed1990

Prognostic value of ovarian carcinoma grading methods--a method comparison study.

The prognostic value of subjective histological and morphometric grading was studied in 75 primary ovarian carcinomas. Histological grading methods recommended by Czernobilsky and by Russell and the morphometric method of Baak and co-workers were compared in a two-observer system. The 5-year survival could be correctly predicted in about two-thirds of the patients with all three methods. When mitotic counting (volume corrected mitotic index, M/V-index) was compared with the above grading methods by using a receiver operating characteristic curve) the M/V-index was generally superior in its prognostic power regardless of the sensitivity/specificity level chosen. The morphometric grading method and the grading method based on the M/V index were also shown to be readily reproducible.

Carcinoma↗

PubMed1986

A comparison of graphical nomogram methods with a computerized Bayesian analysis method in the interpretation of serum phenytoin concentrations.

A study was performed to compare the predictability of a reported Bayesian graphical method, the drug nomogram used in the Bayesian Computer Method and the Driessen Nomogram with that of a computerized Bayesian analysis method in the interpretation of serum phenytoin concentrations. It was found that the results generated by the graphical method were similar to those of the computer with a mean prediction error of 3.9 mg/day in the dose to achieve a concentration at steady-state of 20 ml/l. Overall the results of the graphical method were less biased and had more precision with a significant improvement in relative precision (P less than 0.01) than the initial estimate or Driessen methods.

Adolescent↗

PubMed1987

Comparative analysis of two rapid automated methods and a semiautomated version of the urease method for determining aminoglycoside concentrations in serum.

The Syva EMIT Autolab 6000 and the Abbott TDX automated methods for measuring serum aminoglycoside concentrations were compared with each other and with a new semiautomated version of the urease technique. Each was evaluated for accuracy, reproducibility, cost, and ease of use. All three methods gave satisfactory results, although the Abbott TDX was the most accurate. Both automated methods gave results within minutes, whereas the new urease method, which involved more initial manipulation, took 1.25 h to complete (mainly incubation time). There was no difference in accuracy of performance between experienced and inexperienced operators. The new urease method was much cheaper in terms of initial capital expenditure and in cost per test and needed no provision of manufacturer's back-up maintenance services. This could prove invaluable in situations where financial resources are at a premium. Otherwise, the Abbott TDX is currently our method of choice, and reasons for its preference to the EMIT system are listed.

Anti-Bacterial Agents↗

PubMed2025

A universal, high-quality, and high-yield DNA purification method for mycobacteria, including Mycobacterium tuberculosis: large-scale assessment of the chloroform-bead method.

UNLABELLED: Genomic analysis of mycobacteria has become increasingly crucial for understanding drug-resistance mechanisms, molecular epidemiology, and pathogenesis. However, efficient extraction of high-molecular-weight genomic DNA from these organisms remains challenging because of their thick mycolic acid-rich cell walls. In this study, we report the chloroform-bead method, a universal DNA extraction protocol that combines chemical and mechanical disruptions to overcome these challenges. Multi-laboratory evaluation (16 sites) demonstrated the chloroform-bead method's superiority over conventional methods for Mycobacterium tuberculosis (DNA yield: 17.9 vs 1.9 µg, purity A260/A230: 1.86 vs 1.22, both P < 0.001). Single-facility assessment extended these findings to >32 nontuberculous mycobacterial species (n = 1,058), showing performance comparable to M. tuberculosis (n = 1,000), with both achieving median yields of 22.2 µg DNA and consistent quality metrics. The chloroform-bead method significantly reduced the processing time from 2 to 3 days to 2 h while ensuring complete sample sterilization, eliminating the need for species-specific optimization. This streamlined and universally applicable protocol represents a practical advancement in mycobacterial DNA extraction methodology, ideal for high-throughput genomic studies and routine clinical diagnostics. IMPORTANCE: Mycobacterial genomics is crucial for understanding pathogenesis and drug resistance; however, DNA extraction remains a significant challenge because of its unique cell wall. Traditional methods rely on enzymatic treatments, resulting in complex and time-consuming protocols with variable results. The chloroform-bead method introduces a paradigm shift by chemically and mechanically disrupting the mycolic acid layer and eliminating the need for enzymatic treatment. This standardized approach ensures consistent, high-quality DNA extraction across diverse mycobacterial species, thereby enhancing research capabilities and clinical applications.

Chloroform↗

PubMed1975

The acetyltransferase enzyme method for the assay of serum gentamicon concentrations and a comparison with other methods.

The adenylytransferase/acetyltransferase methods of gentamicin assay have been evaluated for accuracy, speed, and cost. For a comparable cost of materials the latter method is more accurate than that using the adenylytransferase enzyme. The acetyltransferase method is much quicker than the adenyltransferase due to the shorter time necessary for radioactive counting. Sonication is an easier method of enzyme preparation than the previously used osmotic shock technique. The acetyltransferase method is reproducible and there was a very good correlation between it and a microbiological agar-plate diffusion method.

Acetyltransferases↗

PubMed1979

Superiority of a soil debris isolation method over a beet seed colonization method for assay of Rhizoctonia solani at high soil inoculum densities.

A quantitative soil debris isolation method (all debris from known weight of soil plated) and a garden beet seed saprophytic colonization method were compared over a 1-year period for assaying Rhizoctonia solani population. Four fields of different soil textures were selected. Within each field four areas of healthy and four areas of diseases (rhizoctonia root and crown rot) sugarbeets were sampled bimonthly from August 1976 until June 1977. The maximum numbers of R. solani colonies obtained by the debris method were 2 per gram of soil in areas of healthy beets, and 11 per gram of soil in areas of diseased sugarbeets. At such high inoculum densities the beet seed colonization method underestimated R. solani populations, because the inoculum per unit of soil exceeded the numbers of beet seeds per unit of soil available for colonization. Modifications of the beet seed method did not significantly alter results of colonization assays. Ranked correlation comparisons of assay methods yielded r = 0.81 for all data.

Mitosporic Fungi↗

PubMed1985

Methods of assigning accurate values to reference serum. Part 2. The use of definitive methods, reference laboratories, transferred values and consensus values.

Eight analytes (Ca, Cl, cholesterol, glucose, Mg, K, Na and urate) have been determined in one horse serum masterlot by up to six different procedures: (i) by so-called definitive methods; (ii) by a group of reference laboratories using a variety of analytical methods; (iii) using the results of two independent external quality assessment schemes; (iv) by transferring values from a human serum standard reference material analysed by definitive methods; (v) by similar transfer of values from several batches of horse reference serum previously analysed by definitive methods; and (vi) as in (v) but using a group of reference laboratories. The results have confirmed the validity and usefulness of the transfer process in value assignment and in identifying outliers due to inaccurate methods. Definitive methods are shown to be subject to error, and although they appear to be the most accurate single techniques currently available, they are not definitive in the sense of being without bias and having no known source of inaccuracy.

Animals↗