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PubMedDate not supplied

[Individualized monitoring of the therapy with gentamycin using pharmacokinetic methods. Which method to choose?].

Gentamicin has an excellent cost/efficacy ratio for gram negative infections treatment. Its use is often limited in clinical practice by its narrow safety margins and a high incidence of toxicity. Gentamicin related nephrotoxicity is a major adverse effect, mostly in patients with other concomitant potential risk factors. As many other Authors we have found in our Internal Medicine Service during 1992 a gentamicin related nephrotoxicity incidence of 22.5%. Various empiric methods and nomograms have shown a significant incidence of error in predicting individualized gentamicin dosage regimens. Pharmacokinetics methods have demonstrated much better results regarding efficacy and toxicity. The aim of this prospective study carried out during 1993-1994 was to individualize by pharmacokinetics methods dosage regimens of gentamicin in patients with one or more concomitant risk factors of nephrotoxicity. The purpose of pharmacokinetics dosage regimens has been to achieve trough serum concentrations of gentamicin in therapeutics range-0.5 to 2 micrograms/ml-on the first 24 to 48 hours of treatment, and the maintenance in this range during all the treatment, avoiding both toxic and under therapeutic levels. The incidence of gentamicin related nephrotoxicity has been evaluated in this population. Twenty patients were studied: 18 males and 2 females aged 59.6 years (19 to 85). All had one or more potential risk factors for nephrotoxicity-65 years or more: 13, previous renal failure: 6, other nephrotoxic drugs: 10, diuretics: 4, dehydration: 5, congestive heart failure: 5, diabetes: 3, hypertension: 3. For the first 10 patients gentamicin dosage regimens have been determined by Sawchuk-Zaske pharmacokinetics method and for the subsequent 10 patients by Bayesian method. The two subpopulations had no significant differences regarding mean age, sex and potential risk factors for nephrotoxicity. Results of Sawchuk-Zaske method: 53 trough gentamicin serum concentration were obtained; 86.8% were within the therapeutic range, 7.5% were toxic and 5.7% were under therapeutic. Results of Bayesian method: 44 determinations of gentamicin through concentrations were obtained; 86.3% within therapeutic range, 2.4% were toxic and 11.3% were under therapeutic. A great variability in pharmacokinetic patient's profile has been found and explains the great variability of individualized dosage regimens of gentamicin (30 to 320 mg/day). No patients had gentamicin related nephrotoxicity. Both pharmacokinetics methods lead to a efficient and save employment of gentamicin in patients with previous renal failure and other potential risk factors for nephrotoxicity.

Adult↗

PubMed1997

[Comparison of the DNA-GEN Probe PACE 2 method and the LCR method for the detection of Chlamydia trachomatis in the female genital tract].

OBJECTIVE: Comparison of two methods of so-called rapid assessment of Chlamydia trachomatis in the urogenital system, i.e. the hybridization method GEN-Probe PACE 2 and the amplification LCR (ligase chain reaction) method. In 1995-1996 the authors made a screening examination to detect Chlamydiae in the urogenital tract by means of the hybridization method GEN-Probe PACE 2 and the amplification LCR method in selected groups of patients of the Second Gynaecological and Obstetric Clinic, First Faculty Hospital, Prague. The methods were evaluated as to their sensitivity. The examinations of the samples were made in the serological laboratory of the First Dermatological Clinic of the First Faculty Hospital Charles University, Prague. The amplification method is twice as sensitive as the hybridization method.

Adult↗

PubMed1998

The regional Monte Carlo method: a dose calculation method based on accuracy requirement.

In this work we propose the regional Monte Carlo (RMC) method of dose calculation. This method combines the Monte Carlo (MC) algorithm and a non-MC algorithm (such as the convolution method) for optimal speed and accuracy in dose calculation for both photon and electron beams and for various irradiation and patient geometries. For specific regions in the geometry where high accuracy is required but difficult to obtain with analytical or empirical calculations, such as critical organs surrounded by complicated inhomogeneities, the MC algorithm is used. For regions with simple geometries, or where a high degree of dose accuracy is not critical, the non-MC algorithm is used to increase speed. There are two aspects of the RMC method. The first one involves determining critical regions and boundaries, and the other involves the actual implementation and mixing of the two computational algorithms. Two examples of different geometries are used to illustrate the different ways to apply the RMC method. The possibility to extend the method to more complicated geometries and inhomogeneities, as well as the ability of the method to incorporate different calculation algorithms, are also discussed.

Algorithms↗

PubMed1989

[Studies on the method of measurement of odorants dissolved in water--the simplified head space method].

An improved and simplified Head Space Method was devised for measurement of the concentration of odorants dissolved in waste water, and this method was examined to determine whether it was applicable for this purpose or not. This method is taken into consideration the variableness of liquid concentration and of gas pressure resulting from the volatilization of odorants and aqueous vapor to the atmosphere. By this method, the constants of hydrogen sulfide, dimethylsulfide and trimethylamine were measured under various temperatures and pHs. As a result of comparison with the measured values obtained by the Stripping Method and those from the heretofore used Head Space Method, this method appeared to be fairly applicable.

Hydrogen-Ion Concentration↗

PubMed1992

[Comparative study of single-point method and multipoint method in the measurement of estrogen receptor and progesterone receptor in breast cancer].

A comparative study of estrogen receptor (ER) and progesterone receptor (PgR) by single-point method and multi-point method in dextran coated charcoal assay (DCC) was carried out in 50 and 47 cases of breast cancer, respectively. Taking 10 fmol/mg protein as the positive value, the conformation rate of both methods in ER measurement was 96.0% (48/50) with r = 0.978 by linear regression analysis (P less than 0.001). In PgR measurement, the conformation rate of both methods was 95.7% with r = 0.988 (P less than 0.001). Statistically, the difference between single-point method and multi-point method in the ER and PgR measurements was not significant (P greater than 0.5) both in rank-sum test and in paired t-test. The authors suggest that ER and PgR of breast cancer samples be measured with single-point method for its simplicity and less tumor tissue required.

Breast Neoplasms↗

PubMedDate not supplied

Evaluation of three methods for measurement of femoral neck anteversion. Femoral neck anteversion, definition, measuring methods and errors.

A variety of methods exist for determining femoral neck anteversion. There is, however, no consistent definition or reference method by which the correctness of the measurements can be determined. In this report the precision of a specific definition of femoral neck anteversion is estimated by means of a reference method. Three different radiologic measuring methods based on fundamentally different principles are evaluated by comparison with this reference. It is concluded that: 1) The Dunlap/Rippstein method can be recommended as the standard method. 2) Computed tomography may have substantial sources of error. 3) Methods based on arbitrary projections have poor precision.

Femur Neck↗

PubMed1976

[The fecal flora of man. IV. Communication: Comparison of the newly developed method with the old conventional method for the analysis of intestinal flora (author's transl)].

The results of 42 fecal flora analysis of healthy adult men were compared by using a newly developed method and an old conventional method. Statistical estimate indicate, that with the new method the total counts and the counts of bifidobacteria, catenabacteria (eubacteria and anaerobic lactobacilli), peptostreptococci, and clostridia (except Cl. perfringens) as well as the occurences of peptostreptococci and spirillaceae were significant higher than with the use of the old method. On the other hand the counts and occurences of bifidobacteria, veillonellae, Cl. perfringens, Megasphaerae and aerobes were similar with both method. With the new method the total counts of feces of healthy adult men nubmered 1-2 X 10(11) per g wet weight, and fastidious anaerobes, such as bacteroides, catenabacteria and peptostreptococci, were always occurred as predominant flora. The results suggest that the conventional anaerobic jar method is inadequate for the isolation of fastidiuos anaerobes and indicate that the use of modified medium 10 in combination with strict anaerobic technique is necessary for the analysis of fecal flora.

Adult↗

PubMed1975

[Comparison of conventional methods for the determination of albumin, transferrin and ceruloplasmin in serum with immunological reference methods (author's transl)].

Radial immunodiffusion, which is a presently accepted reference method, was compared with the mechanized immunoprecipitation. Each of these specific methods was compared with two normal clinical-chemical methods for the determination of albumin and transferrin, and an enzymic method for the determination of ceruloplasmin. The correlation coefficients, the mean slope for regression, and the percentage variation of the average values from those of the average values of the reference methods are presented. In the determination of albumin and ceruloplasmin, radial immunodiffusion and mechanized immunoprecipitation give the same results. Surprisingly, these two specific methods give different results in the determination of transferrin. In as far as there is no doubt concerning the accuracy of the mechanized immunoprecipitation, this method is recommended, since it also has the advantage of being less demanding in cost and time.

Autoanalysis↗

PubMed1983

Measurement of functional residual capacity during mechanical ventilation. Comparison of a computerized open nitrogen washout method with a closed helium dilution method.

The functional residual capacity of patients treated with mechanical ventilation was measured with two methods: the closed helium dilution method and the open nitrogen washout method with a computerized system. Measurements of FRC were made with and without PEEP. The results obtained did not show significant differences between the methods. Additionally we checked the accuracy of the open nitrogen washout method to measure FRC of patients and healthy subjects breathing high concentrations of oxygen which was the same as breathing air. Both methods were equally reliable and safe when measuring the FRC of patients on mechanical ventilation but the nitrogen method was easier and quicker.

Computers↗

PubMed1996

Rational experimental design for bioanalytical methods validation. Illustration using an assay method for total captopril in plasma.

Generally, bioanalytical chromographic methods are validated according to a predefined programme and distinguish a pre-validation phase, a main validation phase and a follow-up validation phase. In this paper, a rational, total performance evaluation programme for chromatographic methods is presented. The design was developed in particular for the pre-validation and main validation phases. The entire experimental design can be performed within six analytical runs. The first run (pre-validation phase) is used to assess the validity of the expected concentration-response relationship (lack of fit, goodness of fit), to assess specificity of the method and to assess the stability of processed samples in the autosampler for 30 h (benchtop stability). The latter experiment is performed to justify overnight analyses. Following approval of the method after the pre-validation phase, the next five runs (main validation phase) are performed to evaluate method precision and accuracy, recovery, freezing and thawing stability and over-curve control/dilution. The design is nested, i.e., many experimental results are used for the evaluation of several performance characteristics. Analysis of variance (ANOVA) is used for the evaluation of lack of fit and goodness of fit, precision and accuracy, freezing and thawing stability and over-curve control/dilution. Regression analysis is used to evaluate benchtop stability. For over-curve control/dilution, additional to ANOVA, also a paired comparison is applied. As a consequence, the recommended design combines the performance of as few independent validation experiments as possible with modern statistical methods, resulting in optimum use of information. A demonstration of the entire validation programme is given for an HPLC method for the determination of total captopril in human plasma.

Calibration↗

PubMed1990

Methods for estimating release rates during high frequency quantal secretion and for testing such methods.

The rate of spontaneous quantal release must be estimated in some investigations of synaptic transmission, even when frequencies are so high that individual quanta cannot be distinguished. An obvious method is to measure the time integrals of the summed MEPPs and then dividing this value by the integral of an average MEPP. The method was tested by recording miniature end-plate potentials (MEPPs) at frog neuromuscular junctions, counting the number of MEPPS, and then adding together records from the same junction to simulate high frequencies. The estimates from the integral method agreed well with the actual counts. The method can readily be used with a microcomputer and does not require stationary data. Methods based on fluctuation analysis were also used to estimate quantal frequencies, but they did not always give good estimates. This was not a thorough test of the fluctuation method, but an example of testing with MEPP data. The integral method might be reasonably reliable, but there are further potential complications, like changes in MEPP size and short-circuiting of the end-plate membrane, which may make it difficult to obtain reliable measurements of high frequency quantal secretion without voltage clamping and protocols that permit measurements of individual MEPCs during the course of the frequency measurements.

Animals↗

PubMed1996

Water turnover evaluated by the tritiated water method and by the nutritional method in European hedgehog (Erinaceus europaeus L.).

The total body water (TBW), the fractional water turnover rate (WTR), and the water flux rates (WFR) were studied for the first time by the tritiated-water method in 10 hedgehogs under laboratory conditions during the year. To validate this method, we compared the result to the nutritional method. The TBW varied inversely with body mass (BM) during both the active and the hibernation periods. The WTR varied from 16% to 21% during the hibernation period and after the reproduction. The higher values (from 22% to 26%) were recorded during the reproduction period and during the preparation for hibernation. The same variations in WFR were recorded during the active and hibernation period. The net gain or loss of water followed the gain and loss of BM. The tritiated water (THO) method has been validated by the fact that the same variations in WFR during each month have been measured by the THO method and the nutritional method. Moreover, the THO method can be used to estimate the changes in energy metabolism of hedgehogs in relation with the seasons.

Analysis of Variance↗

PubMed1996

Comparative study of bone mineral density estimated by various methods of single- and dual-energy quantitative computed tomography: the capability of the four-equation four-unknown method.

A dual-energy (DE) quantitative computed tomography (QCT) method, the four-equation four-unknown method (DEQCT 4E-4U), was assessed and compared to single-energy (SE) QCT and standard DEQCT (two-line method). The results of this study indicate that bone mineral density (BMD) was more accurately estimated by the present method than by the SEQCT or standard DEQCT techniques on the basis of a phantom study when a large fat content was present. The results of both the phantom study and a human study also showed that the present method corrected for fat in estimating BMD in the presence of high-fat content. These findings suggest that use of this method for estimating BMD can provide useful information in studies assessing the metabolic state of bone. We propose that CT numbers estimated from excised vertebral bone marrow can serve as a soft-tissue correction for the present method.

Adult↗

PubMed2026

An enhanced multisegment RT-PCR method for influenza A virus sequencing: Improved performance and reduced preparation time over traditional methods.

Influenza A viruses (IAVs) remain a major global health threat, affecting both human and animal populations. Whole-genome sequencing is essential for monitoring viral evolution, zoonotic transmission, and emerging variants. However, conventional RT-PCR methods often result in incomplete gene coverage, amplification biases, and reduced sequencing accuracy, particularly in clinical samples. We developed a robust In-house method for IAV full-genome sequencing using the Oxford Nanopore Technologies (ONT) long-read sequencing platform. This method integrates an in-house multisegment Reverse Transcription PCR (RT-PCR) method with a streamlined 2-pool primer design targeting all eight IAV gene segments. RNA extracted from clinical and stock virus samples was reverse-transcribed and amplified using Superscript IV-based chemistry, followed by magnetic bead purification to ensure high-quality amplicons. Sequencing libraries were prepared with the Native Barcoding Kit 24 (SQK-NBD114.24) and sequenced on R10.4.1 flow cells on the MinION MK1C device. Data analysis using the Iterative Refinement Meta-Assembler (IRMA) confirmed improved read depth, uniform coverage, and complete genome recovery. Compared to conventional methods, our In-House Multisegment 2-Pool (IH-MS2P) RT-PCR method generated higher numbers of matched read counts, minimized chimeric artifacts, and delivered superior genome coverage across human, swine, and avian isolates. This optimized RT-PCR method provides a high-performance, time-efficient, and portable solution for influenza genomics, demonstrating robust applicability even with clinical samples of low RNA yield.

Influenza A virus↗

PubMed1985

Light microscopical localization of enzymes by means of cerium-based methods. I. Detection of acid phosphatase by a new cerium-lead-technique (Ce-Pb-method).

Cerium-III-ions are more and more used as capturing reagent and opaque marker for the electron microscopic localization of a number of H2O2-generating enzymes as well as phosphohydrolases. Contrary to its advantages over common lead methods in the histochemical detection of enzyme activities at the electron microscopic level, cerium-based methods proved to be a failure for light microscopic investigations. Therefore, our cerium-based method for the ultrahistochemical detection of acid phosphatase was developed for further observations at the light microscopic level. The principle of that new Ce-Pb-method is the conversion of light microscopic not visible cerium phosphate into lead phosphate by the secondary capture reagent alkaline lead citrate. Finally, the lead phosphate can be visualized as lead sulfide in the section. The Ce-Pb-method in its finally proposed manner was compared with a common lead method and showed a range of advantages. Because of that fact, the new Ce-Pb-method is recommended for a broader use in histochemistry, e.g. for the light microscopic enzyme investigation parallel to ultrahistochemical preparations.

Acid Phosphatase↗

PubMed1986

The "Ring" method: a semi-empirical method to calculate dose distributions of irregularly shaped photon beams.

The "Ring" method provides a fast dose calculation and isodose presentation for photon beams with blocks. The method takes into account the change in scatter due to the blocks at each calculation point. Firstly, the dose in a point is calculated assuming that no blocks are present. Secondly, the scatter reduction caused by the blocks is calculated and subtracted. To determine the scatter reduction the irradiated surface is divided in concentric rings around a point at the surface at the intersection with a ray line between focus and calculation point. The scatter reduction caused by blocks for each ring is calculated. The effect of scatter for rings with an outer radius greater than 15 cm where the scatter contribution is less than 1.0% is neglected. Results of the method for 4 MV photons using eight rings are presented. Comparison of dose measurements with calculations in an arrow-shaped photon field showed maximum deviations of 4.0%, using the IRREG program of Cunningham, 6.5% using the BLKINP program of Schlegel, which is based on Clarkson's method, 5.0% using the method of Wrede and 2.2% using the "Ring" method. Contrary to the first two calculation programs, the programs using the last two calculation methods provide isodose lines dose values at points.

Radiation Dosage↗

PubMed1998

Comparison of the proximal flow convergence method and the jet area method for the assessment of the severity of tricuspid regurgitation.

AIMS: To compare the value of the proximal flow convergence method and the jet area method for the determination of the severity of tricuspid regurgitation. METHODS AND RESULTS: The proximal isovelocity surface area radius and the jet area/length were measured in 71 consecutive patients with angiographically graded (grade 0/I-III) tricuspid regurgitation. Rank correlation coefficients with the angiographic grade were 0.71 (P < 0.001) for the proximal isovelocity surface area radius (aliasing border of 28 cm.s-1), 0.66 (P < 0.001) for the jet area, and 0.63 (P < 0.001) for the jet length. The proximal isovelocity surface area radius was significantly correlated with the jet area/length (correlation coefficients 0.82/0.77, P < 0.001). Correct differentiation between mild to moderate (grade I-II) and severe (grade III) tricuspid regurgitation was achieved in 62 of 71 patients (87%) by means of the proximal isovelocity surface area radius, in 61 of 71 (86%) by the jet area, and in 62 of 71 (87%) by the jet length. Grade III tricuspid regurgitation was not identified in five of 21 patients (24%) by means of the proximal isovelocity surface area radius, in six of 21 (29%) by the jet area, and in seven of 21 (33%) by the jet length. CONCLUSION: The flow convergence method and the jet area method are of similar value for the determination of the severity of tricuspid regurgitation. Both methods differentiated mild to moderate from severe tricuspid regurgitation in most patients. However, underestimation of severe tricuspid regurgitation in 20-30% of the cases represents a serious limitation of both methods.

Adult↗

PubMedDate not supplied

Estimates of maximum limits of food colours use in Brazil through the Danish Budget Method and the Bär and Würtzen-modified method.

The establishment of the permissible levels for the use of additives in foods must be based on the Acceptable Daily Intake (ADI). A method that may be applied for this purpose is the Danish Budget Method which estimates the maximum amount of the additive that may be added to the food based on the functional properties of the additive, and on the categories of the food in which the additive will be used. Based on the latest information Bär and Würtzen propose some modifications to the original Budget Method, one of which is the addition of a correction factor which takes into account the competition between different food additives with the same functional properties. In the present paper, both the Budget Method and the Bär and Würtzen-modified method were applied to evaluate whether the maximum levels of food colours use exceeded their ADI or not. Applying the original Budget Method, the results showed that the colours Sunset Yellow, Amaranth, Erythrosine, Ponceau 4R and Cochineal possibly exceeded the ADI; while applying the modified method only the colours Erythrosine and Cochineal would exceed the ADI. Brazilian regulatory authorities should be advised to establish maximum limits of use for the following categories of colours: Caramel, Inorganic, Natural and Artificial Colours Identical to the Natural Ones, where ADIs have been evaluated by JECFA.

Brazil↗