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1
He, Kevin. "Indirect and direct standardization for evaluating transplant centers." Journal of Hospital Administration 8, no. 1 (December 9, 2018): 9. http://dx.doi.org/10.5430/jha.v8n1p9.
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To assess the quality of health care, patient outcomes associated with medical providers are routinely monitored in order to identify poor (or excellent) provider performance. To avoid confounding by risk factors, both indirect and direct standardization have been used for comparing outcome rates or prevalence for different providers. There has been an ongoing debate as to which standardization method is more appropriate. To compare the performance of indirect and direct standardization for the purpose of ranking transplant centers, we analyzed post-transplant mortality using the national kidney transplant data. Included in our analysis were 116,601 patients (from 230 transplant centers) who underwent kidney transplantation between January 2006 and December 2012. Multivariate logistic regression model was used to model the 30-day mortality, which were estimates of failures (grant failure or death) in the 30 days after the transplant surgery. Concordance indexes, kappa coefficients and Spearman’s rank correlation coefficient were computed. The estimated values from these statistics for the indirect standardized method were similar to the direct standardization. The results suggest that both indirect and direct standardized methods provide similar ability to distinguish center effects.
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Wu, Xiaoting, Min Zhang, Ruyun Jin, Gary L. Grunkemeier, Charles Maynard, Ravi S. Hira, Todd MacKenzie, et al. "A Comparison of statistical methods for hospital performance assessment." Journal of Hospital Administration 10, no. 3 (May 24, 2021): 32. http://dx.doi.org/10.5430/jha.v10n3p32.
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During hospital quality improvement activities, statistical approaches are critical to help assess hospital performance for benchmarking. Current statistical approaches are used primarily for research and reimbursement purposes. In this multiinstitutional study, these established statistical methods were evaluated for quality improvement applications. Leveraging a dataset of 42,199 patients who underwent coronary artery bypass grafting surgery from 2014 to 2016 across 90 hospitals, six statistical approaches were applied. The non-shrinkage methods were: (1) indirect standardization without hospital effect; (2) indirect standardization with hospital fixed effect; (3) direct standardization with hospital fixed effect. The shrinkage methods were: (4) indirect standardization with hospital random effect; (5) direct standardization with hospital random effect; (6) Bayesian method. Hospital performance related to operative mortality and major morbidity or mortality was compared across methods based on variation in adjusted rates, rankings, and performance outliers. Method performance was evaluated across procedure volume terciles: small (< 96 cases/year), medium (96-171), and large (> 171). Shrinkage methods reduced inter-hospital variation (min-max) for mortality (observed: 0%-10%; adjusted: 1.5%-2.4%) and major morbidity or mortality (observed: 2.6%-35%; adjusted: 6.9%-17.5%). Shrinkage methods shrunk hospital rates toward the group mean. Direct standardization with hospital random effect, compared to fixed effect, resulted in 16.7%-38.9% of hospitals changing quintile mortality ranking. Indirect standardization with hospital random effect resulted in no performance outliers among small and medium hospitals for mortality, while logistic and fixed effect methods identified one small and three medium outlier hospitals. The choice of statistical method greatly impacts hospital ranking and performance outlier’ status. These findings should be considered when benchmarking hospital performance for hospital quality improvement activities.
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Little, R. R., H. M. Wiedmeyer, J. D. England, A. L. Wilke, C. L. Rohlfing, F. H. Wians, J. M. Jacobson, V. Zellmer, and D. E. Goldstein. "Interlaboratory Standardization of Measurements of Glycohemoglobins." Clinical Chemistry 38, no. 12 (December 1, 1992): 2472–78. http://dx.doi.org/10.1093/clinchem/38.12.2472.
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Abstract The diversity of methods used to measure glycohemoglobins (GHb) makes it difficult to compare patients' results among laboratories. We reported previously the feasibility of providing comparable results from different assays by use of common calibrators. We here compare results from seven different GHb methods calibrated by use of hemolysates assayed by a precise ion-exchange high-performance liquid-chromatographic (HPLC) method for hemoglobin A1c (HbA1c). Thus, regardless of the GHb species measured by the seven methods, results were referenced to the HbA1c content of the calibrators. Without this calibration, GHb values for single samples varied, e.g., from 4.0% to 8.1% and from 10% to 14.2% in the normal and high ranges, respectively. Calibration decreased between-method variability (single sample ranges of, e.g., 4.8% to 5.4% and 9.4% to 10.2% in the normal and high ranges, respectively) and improved interassay precision. We conclude that this approach to calibration of GHb measurements allows direct comparison of results obtained by different methods and improves precision.
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Du, Qiang, Bao Dong Bai, and Li Ke. "A Data Standardization and Reconstruction Method for Magnetic Induction Tomography." Advanced Materials Research 647 (January 2013): 560–65. http://dx.doi.org/10.4028/www.scientific.net/amr.647.560.
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Magnetic induction tomography (MIT) is a biologic tomography technology, which is to obtain the conductivity distribution by detecting the data on the boundary of the imaging area based on the eddy current principle. The small impedance difference between biological tissues makes the eddy current weak, and it leads to a direct effect on the biological impedance measurement and imaging sensitivity. A measured data standardization method is presented in this paper for enhancing the measured data sensitivity, and combined with the back-projection reconstruction algorithm to get reconstruction image. It is applied to a variety of measurement and the simulation experiment based on the calculation results of finite-element methods. The reconstructed images indicate that the method can improve the image resolution and sensitivity, and which provides an effective data standardization and reconstruction algorithm for the magnetic induction tomography.
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Huang, Hui, Shuchang Liu, Junaid Ullah, Zehao Sun, Caicai Liu, Zhao Zhang, and Hangzhou Wang. "Model Maintenance of RC-PLSR for Moisture Content Measurement of Dried Scallop." Transactions of the ASABE 63, no. 4 (2020): 891–99. http://dx.doi.org/10.13031/trans.13728.
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HighlightsThe RC-PLSR model for Haiwan scallop can be transferred to Xiayi scallop.The direct standardization method is suggested for model maintenance.The VSWS-PDS method can be further improved in precision.Abstract. A prediction model for evaluating the moisture content in dried Haiwan scallops was established using hyperspectral imaging (HSI) technology in a previously published study. The accuracy of such models is usually affected by differences in sample species, different environmental conditions such as temperature or humidity, and aging of instruments. In this study, the prediction ability of the RC-PLSR model is improved by correcting the spectra of the tested species of dried scallop (i.e., Xiayi) to solve the problem of model failure caused by sample differences. The results of model maintenance by direct standardization (DS) are compared with those of variety sensitive wavelength selection - piecewise direct standardization (VSWS-PDS). The results showed that after using VSWS-PDS to modify the spectral data of the dried scallop samples, the correlation coefficient of prediction (Rp) of the updated model increased from 0.0890 to 0.9190. However, the root mean square error of prediction (RMSEP) also increased, indicating a need for improved precision. The RC-PLSR model based on DS correction showed Rp of 0.790 and RMSEP of 9.7481%. Model maintenance using the DS method is suggested because DS generally outperformed VSWS-PDS, even with a lower correlation coefficient. Future work on error reduction and sample input is suggested for VSWS-PDS optimization. Keywords: Direct standardization, Hyperspectral images, Model maintenance, Scallop, VSWS-PDS.
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Vink, K. L., W. Schuurman, and R. van Gansewinkel. "Use of the caffeine reagent in direct spectrophotometry of bilirubin." Clinical Chemistry 32, no. 7 (July 1, 1986): 1389–93. http://dx.doi.org/10.1093/clinchem/32.7.1389.
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Abstract The molar absorptivity of unconjugated bilirubin in caffeine reagent is independent of the protein matrix. This finding, together with the simplicity of a dilution step for direct spectrophotometry, will improve the calibration methods of bilirubin and make them more nearly accurate. This is encouraging for the development of a new method for bilirubin determination in neonates; moreover, the caffeine reagent has a clearing influence on the turbidity of human sera. These findings should also be important for standardization, especially because the method of Jendrassik and Gróf is also protein-independent. Therefore, the introduction of one reliable, inexpensive, "universal" standard of bilirubin in bovine serum albumin will be of importance for both methods.
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He, Kevin, and Douglas E. Schaubel. "Methods for comparing center-specific survival outcomes using direct standardization." Statistics in Medicine 33, no. 12 (January 17, 2014): 2048–61. http://dx.doi.org/10.1002/sim.6089.
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Fomin, Vladislav V., Hanah Zoo, and Heejin Lee. "Understanding the Technology Development Process at the Early Standardization Stage." International Journal of IT Standards and Standardization Research 12, no. 2 (July 2014): 1–20. http://dx.doi.org/10.4018/ijitsr.2014070101.
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This research is aimed at developing a document content analysis method to be applied in studies of standardization and technology development. The proposed method integrates two theoretical frameworks: the co-evolutionary technology development framework and the “D-N-S” (Design, Negotiation, Sense-making) framework for anticipatory standardizing. At the backdrop of complex and diversified landscape of science and R&D efforts in the technology domain, and the repeated criticism of the weak link between R&D initiatives and standardization, it is argued that the method offered in this work helps to better understand the internal dynamics of the technology development process at the early stage of standardization or pre-standardization, which, in turn, can help mobilize and direct the R&D initiatives. To demonstrate the practical usefulness of the proposed method, this paper conducts a content analysis of the research contributions presented in the COST Action IC0905 “Techno-Economic Regulatory Framework for Radio Spectrum Access for Cognitive Radio/ Software Defined Radio” (COST-TERRA).
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Yoon, Hyeon, Mi Young Shin, Cheol Ho Yoon, Jae Chun Lee, and Kang Sup Chung. "Preparation and Standardization of Method for Valuable Metals Analysis in Seawaters." Materials Science Forum 544-545 (May 2007): 593–96. http://dx.doi.org/10.4028/www.scientific.net/msf.544-545.593.
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A direct analytical technique was developed and tested for correct estimation of recovery of Eco-elements such as Li, B, Br, in the seawater, and three processed seawaters from Hanjoo Co. Ltd. The reliability of recovery technique and the correct estimation of total recoveries become a major interest before the launch of pilot plant. High matrix solutions are frequently affected in analyte response during instrumental analysis as the concentration of major component changed drastically. To overcome such a complication during standard sample preparation and a better application in pilot plant, a modified matrix matching standard addition method was developed and the reliability was checked. The detection limit of elements in several seawaters analyzed by applying the modified matrix matching standard addition method were 0.144 – 0.258-g/dm3 for lithium, 0.0.013 – 0.18mg/dm3 for boron, and 4.23 – 17.8mg/dm3 for bromine. The instrumental analysis was carried by AAS for lithium and ICP-AES for boron and bromine.
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Gosselin, Robert, Dorothy Adcock, Shannon Bates, Jonathan Douxfils, Emmanuel Favaloro, Isabelle Gouin-Thibault, Cecilia Guillermo, Yohko Kawai, Edelgard Lindhoff-Last, and Steve Kitchen. "International Council for Standardization in Haematology (ICSH) Recommendations for Laboratory Measurement of Direct Oral Anticoagulants." Thrombosis and Haemostasis 118, no. 03 (February 12, 2018): 437–50. http://dx.doi.org/10.1055/s-0038-1627480.
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AbstractThis guidance document was prepared on behalf of the International Council for Standardization in Haematology (ICSH) for providing haemostasis-related guidance documents for clinical laboratories. This inaugural coagulation ICSH document was developed by an ad hoc committee, comprised of international clinical and laboratory direct acting oral anticoagulant (DOAC) experts. The committee developed consensus recommendations for laboratory measurement of DOACs (dabigatran, rivaroxaban, apixaban and edoxaban), which would be germane for laboratories assessing DOAC anticoagulation. This guidance document addresses all phases of laboratory DOAC measurements, including pre-analytical (e.g. preferred time sample collection, preferred sample type, sample stability), analytical (gold standard method, screening and quantifying methods) and post analytical (e.g. reporting units, quality assurance). The committee addressed the use and limitations of screening tests such as prothrombin time, activated partial thromboplastin time as well as viscoelastic measurements of clotting blood and point of care methods. Additionally, the committee provided recommendations for the proper validation or verification of performance of laboratory assays prior to implementation for clinical use, and external quality assurance to provide continuous assessment of testing and reporting method.
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Darma Laksana, I. Ketut. "Standardisasi Pengajaran Bipa: Revaluasi Metode Menuju Kompetensi Komunikatif." Pustaka : Jurnal Ilmu-Ilmu Budaya 20, no. 2 (August 31, 2020): 99. http://dx.doi.org/10.24843/pjiib.2020.v20.i02.p05.
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The method of language teaching to achieve communicative competencies to be a choice in second language learning has not developed widely at this time. This paper aims to present the workings of the Linguistic Method as a form of revaluation of traditional methods of language teaching which are considered to have not met the requirements of BIPA Teaching Standardization. The traditional teaching methods applied so far still revolve around the Direct Method and Translation Method. Both of these methods are suspected of not being able to bring learners to communicative competence. The application of the Direct Method has not shown maximum results because it only relies on teaching methods by prioritizing the use of the target language (second language), but the issue of teaching material does not receive an adequate portion to achieve the expected communicative competence. Similarly the Translation Method which basically attempts to convey material by translating it into learner language (generally in English to deal with heterogeneous classes), nor touching teaching material. In connection with that, Cognitive Linguistics which gave birth to Cognitivism Theory and is known as the Linguistic Method in second language teaching is important to be applied to achieve communicative competence. By the standardization it means that method of language teaching must be measured by the linguistic methods itself as a guidance: teaching each aspect of language, such as grammatical patterns, vocabulary groups, and sound devices is carried out in five stages, namely recognition, imitation, repetition, variation, and selection.
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Wang, Weihao, Christian W. Huck, and Bin Yang. "NIR model transfer of alkali-soluble polysaccharides in Poria cocos with piecewise direct standardization." NIR news 30, no. 5-6 (June 21, 2019): 6–14. http://dx.doi.org/10.1177/0960336019855218.
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Objective To investigate the feasibility for establishing near-infrared spectra model transfer with traditional Chinese medicine. Method Poria cocos, a kind of fungi (called “ Fuling” in Chinese), was used as an investigative object. NIR quantification model transfer of alkali-soluble polysaccharides in Poria cocos was studied. Spectra were obtained from Thermo Antaris II (master device) and Buchi NIRFlex N-500 (slave device), respectively. Procedures and factors that may have effects on the performance of spectral standardization have been investigated. Spline interpolation was applied to align spectra from two different instruments, and piecewise direct standardization was employed to standardize spectra from slave instrument. Full cross-validation was used to evaluate the result of model transfer. Results Spectral pre-processing including multiplicative signal correction and wavelength selection played an important role in operating the model transfer. Spectra within the region of 9000–6500 cm−1 provided relatively good transfer result. In addition, increasing window size had positive effect on improving the spectral transfer. In this study, a window size of 13 provided the best spectra standardization result. Test validation with five samples produced the best full cross-validation result with the values of correlation coefficient of calibration ([Formula: see text]), correlation coefficient of prediction ([Formula: see text]) and root mean square error of prediction as 0.86, 0.73 and 2.3, respectively. Conclusion In this study, many factors influenced the quality of the transferred slave spectra. And it is hard to provide a pretty good quantitative model transfer result about alkali-soluble polysaccharide in Poria cocos. The following factors have great effects on the quality of model transfer: (i) multiplicative signal correction which is necessary for model building; (ii) increasing the window size which has a positive effect on slave spectra standardization; (iii) a proper wavelength region benefits for model building; (iv) a proper scale of standardization group including proper samples is necessary.
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Despagne, Frédéric, Beata Walczak, and Desire-Luc Massart. "Transfer of Calibrations of Near-Infrared Spectra Using Neural Networks." Applied Spectroscopy 52, no. 5 (May 1998): 732–45. http://dx.doi.org/10.1366/0003702981944157.
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A new approach for multivariate instrument standardization is presented. This approach is based on the use of neural networks (NNs) for modeling spectral differences between two instruments. In contrast to the piecewise direct standardization (PDS) method to which it is compared, the proposed method builds a single transfer model for all spectral windows. The apparently incompatible requirements for a high number of training objects and a low number of standardization samples are addressed by truncating spectra in finite-size windows and assessing a position index to each window. Each spectral window with the corresponding position index constitutes a training object. No prior background correction is required with this method. Both the proposed method and PDS were applied to some real and simulated data sets, and results were evaluated for reconstruction and subsequent calibration. On the studied data sets, the neural network approach was found to perform at least as well as PDS for both reconstruction and calibration.
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Kibona, Shadrack E., and Christopher H. Mbotwa. "Comparison of Mortality by Gender and Regions in Tanzania using Direct Standardized Death Rates (DSDR) Method." Tanzania Journal of Health Research 21, no. 1 (July 24, 2020): 1–7. http://dx.doi.org/10.4314/thrb.v21i1.1.
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Background: Comparison of mortality is very useful in assessing population health. Crude rates can easily be computed from the mortality but they are not good for comparison across groups of the population. The aim of this paper was to compare mortality in Tanzania by region and gender using the 2012 Tanzania Population and Housing Census.
Methods: Age-specific death rates for regions, Tanzania Mainland, Tanzania Zanzibar and entire Tanzania were obtained from Mortality and Health monograph data downloadable from the National Bureau of Statistics website. The direct standardization method was used to compare the mortality for male and female populations across all regions of Tanzania Mainland and Zanzibar.
Results: Findings show that the mortality is low in Arusha, Manyara, and Kilimanjaro compared to other regions in Tanzania mainland implying that health status for both male and female population in those regions is better than the other regions while it is the worst in Njombe, Iringa, and Kagera implying the poor health status for those regions as compared to the rest regions in Tanzania Mainland. In Tanzania Zanzibar, high mortality was observed in Kusini Unguja and the lowest in Kaskazini Unguja for both male and female populations. By national wise and for almost all regions, the mortality for the male population is higher than that for the female population.
Conclusion: Direct standardization methods can save as the best way for comparing mortality because it takes into consideration both the population at risk and the age structure. However, in estimating mortality, crude death rates should be used to give the magnitude while direct standardized death rates should be used for comparison purposes.
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Ngowsuwan, K., D. Thanapatay, and S. Kasemsumran. "Performance improvement of temperature compensation in near infrared analysis of orange sweetness by applying direct standardization." Journal of Near Infrared Spectroscopy 26, no. 6 (October 14, 2018): 369–78. http://dx.doi.org/10.1177/0967033518805271.
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Near infrared spectroscopy is a non-destructive technique used for measuring and analyzing chemical compositions in an organic sample. The calibration equation and spectrum are used for calculating the prediction result. In this case, the spectrum provides very important data; therefore, the accuracy of the near infrared prediction system depends on the sample preparation because the spectrum is sensitive to physical property conditions such as sample temperature. When the sample temperature has changed, the absorption peak will be shifted nonlinearly in both the absorption value and wavelengths around 840 nm and 940 nm (in the short regions). Consequently, if applying a calibration model developed from spectra of a constant sample temperature by using a linear multivariate data analysis to predict the samples with different temperature conditions, the average of difference between actual values and predicted values (bias) will occur. Therefore, the objective of this research was to develop a spectra temperature compensation method namely the temperature compensation coefficient method by applying direct standardization algorithm. By the use of temperature compensation coefficient, the temperature effect can be solved and the accurate prediction results can be obtained. Moreover, the performance of temperature compensation coefficient was investigated and compared with the fixed temperature and three compensation methods, such as generalized least squares weighting, external parameter orthogonalization, and global calibration. The results indicated that temperature compensation coefficient method and the global calibration gave the best result with high accuracy of the lowest bias at 95% confident level.
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Laref, Rachid, Etienne Losson, Alexandre Sava, and Maryam Siadat. "Support Vector Machine Regression for Calibration Transfer between Electronic Noses Dedicated to Air Pollution Monitoring." Sensors 18, no. 11 (November 1, 2018): 3716. http://dx.doi.org/10.3390/s18113716.
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Recently, the emergence of low-cost sensors have allowed electronic noses to be considered for densifying the actual air pollution monitoring networks in urban areas. Electronic noses are affected by changes in environmental conditions and sensor drifts over time. Therefore, they need to be calibrated periodically and also individually because the characteristics of identical sensors are slightly different. For these reasons, the calibration process has become very expensive and time consuming. To cope with these drawbacks, calibration transfer between systems constitutes a satisfactory alternative. Among them, direct standardization shows good efficiency for calibration transfer. In this paper, we propose to improve this method by using kernel SPXY (sample set partitioning based on joint x-y distances) for data selection and support vector machine regression to match between electronic noses. The calibration transfer approach introduced in this paper was tested using two identical electronic noses dedicated to monitoring nitrogen dioxide. Experimental results show that our method gave the highest efficiency compared to classical direct standardization.
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Rifai, Nader, Thomas G. Cole, Elizabeth Iannotti, Terence Law, Michael Macke, Richard Miller, Dennis Dowd, and Donald A. Wiebe. "Assessment of interlaboratory performance in external proficiency testing programs with a direct HDL-cholesterol assay." Clinical Chemistry 44, no. 7 (July 1, 1998): 1452–58. http://dx.doi.org/10.1093/clinchem/44.7.1452.
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Abstract Direct assays for the determination of HDL-cholesterol (HDL-C) have recently become available. The methods are precise, require small sample volume, and appear to be less affected by increased triglycerides than traditional precipitation methods. In this study, we describe the inter- and intralaboratory variability of the Boehringer Mannheim Corporation direct HDL-C assay and its performance in external proficiency testing surveys. A comparison study among three laboratories, using different analyzers and 85 serum specimens, showed a correlation coefficient (r) of 0.99. The direct HDL-C assay also showed good agreement with the ultracentrifugation-dextran sulfate-Mg2+ method (r = 0.98) and the Cholesterol Reference Method Laboratory Network-Designated Comparison Method (a = 0.98x + 4.75 mg/L, r = 0.98). Total error at medical decision levels ranged from −0.8% to +11.1%. Furthermore, this assay performed adequately in the College of American Pathologists and the ALERT® surveys as well as the CDC Lipid Standardization Program and met all performance criteria of regulatory agencies.
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Serteser, Mustafa, Abdurrahman Coskun, Tamer C. Inal, and Ibrahim Unsal. "Challenges in vitamin D analysis / Izazovi u analizi vitamina D." Journal of Medical Biochemistry 31, no. 4 (October 1, 2012): 326–32. http://dx.doi.org/10.2478/v10011-012-0016-z.
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Summary Vitamin D is an important determinant for the regulation of calcium and phosphorus levels and mineralization of the bone. The most reliable indicator of vitamin D status is the measurement of plasma or serum 25OH-D concentration. Several studies reported discrepancies between the results of assays. These high variabilities in 25OH-D measurements are due to used assay technologies and lack of standardization against the reference materials. Different assays have been employed for the measurement of 25OHD levels: Competitive Protein Binding Assays, immunoassays, direct detection methods. Choosing an assay platform is important both for clinical laboratory professionals and researchers, and several factors affect this process. Recently, liquid chromatography and tandem mass spectrometry is an alternative method to traditional assays and provides higher specificity and sensitivity than many assays; therefore, it has been suggested as a candidate reference method for circulating 25OH-D3. Standardization of methods for the quantification of 25OH-D by using the human-based samples would reduce the inter-method variability. The best way for laboratories to demonstrate the accuracy of their results is by participating in the external quality assessment scheme. Standardization of the assays is also required to provide clinicians with the accurate tools to diagnose hypovitaminosis. In addition, assay-specific decision limits are needed to define appropriate thresholds of treatment.
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Sampei, Míriam Akemi, and Dirce Maria Sigulem. "Field methods in the evaluation of obesity in children and adolescents." Revista Brasileira de Saúde Materno Infantil 9, no. 1 (March 2009): 21–29. http://dx.doi.org/10.1590/s1519-38292009000100003.
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In large samples, the methods for obtaining information on obesity need to be simple, inexpensive and reasonably accurate. This review deals with articles focusing on various field methods for the evaluation of body composition. The Bioimpedance and Near Infrared methods are simple to execute but their advantage in relation to Body Mass Index is obscure. Although the Bioimpedance and near infrared methods provide estimates of fat content, they may be no better than waist circumference measurements. The latter does not distinguish body fat but points to a more direct relationship concerning health risk. Regardless of the advantages, waist circumference continues to be under discussion: there is a lack of standardization and no reference populations or cutoff points have been established. No perfect method exists, but the number of errors could be reduced, if care were taken in drawing up protocols, standardization, and the analysis of sample properties.
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Fogh-Andersen, Niels, and Paul D’Orazio. "Proposal for standardizing direct-reading biosensors for blood glucose." Clinical Chemistry 44, no. 3 (March 1, 1998): 655–59. http://dx.doi.org/10.1093/clinchem/44.3.655.
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Abstract Direct-reading glucose biosensors sense molality (glucose per unit water mass) in the sample. With aqueous calibration, a direct-reading glucose biosensor produces higher results in blood and plasma than methods measuring concentration, theoretically by the ratio of water concentrations in calibrator and sample. To confirm this, we measured glucose in 140 blood and 40 plasma samples with the direct-reading glucose sensor in the Chiron Model 860 Blood Gas and Critical Analyte System and with our routine method (ESAT 6660; Eppendorf). The Chiron instrument is calibrated with a 10 mmol/L (180 mg/dL) glucose calibrator (mass concentration of water = 0.99 kg/L). Assuming normal water concentrations of 0.84 and 0.93 kg/L in blood and plasma, respectively, we multiplied results from the Chiron sensor by 0.84/0.99 and 0.93/0.99 to obtain concentrations in blood and plasma. This conversion resulted in agreement of results with our routine method. An individual conversion based on hematocrit in each whole-blood sample was less satisfactory. To avoid confusion over variously measured and reported glucose results and reference values, we suggest standardization and reporting of whole-blood glucose results as equivalent plasma concentrations. This proposal may be conveniently achieved by using a commercially available reference material for glucose, NIST SRM 965.
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Swierenga, H., W. G. Haanstra, A. P. De Weijer, and L. M. C. Buydens. "Comparison of Two Different Approaches toward Model Transferability in NIR Spectroscopy." Applied Spectroscopy 52, no. 1 (January 1998): 7–16. http://dx.doi.org/10.1366/0003702981942528.
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Recently, efficient methods have become available to transfer a multivariate calibration model from one instrument to another. Two categories can be distinguished: improvement of the robustness of the calibration model by, for example, a proper data preprocessing; and adaptation of the calibration model by, for example, (piecewise) direct standardization. In direct standardization, a subset from the calibration set should be measured on both instruments. Usually, however, the calibration samples cannot be measured on both instruments. When data preprocessing is applied to the transfer of multivariate calibration models, there is no need for remeasurement of a subset on both instruments. In this paper, both categories are compared for the determination of the component concentrations in a ternary mixture of methanol, ethanol, and 1-propanol using NIR spectroscopy. The calibration models obtained on one instrument are transferred to other NIR instruments. It has been found that the results of proper data preprocessing are comparable with the results obtained by direct standardization when the models are transferred over three NIR instruments.
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He, Y. C., P. W. Chan, and Q. S. Li. "Standardization of Offshore Surface Wind Speeds." Journal of Applied Meteorology and Climatology 55, no. 5 (May 2016): 1107–21. http://dx.doi.org/10.1175/jamc-d-15-0299.1.
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AbstractWind measurement offers an essential data source for a wide range of practices in the fields of meteorology and wind engineering. However, records of surface winds are usually influenced by terrain/topographic effects, and direct usage of raw data may bring in nonignorable errors for follow-up applications. A data-driven standardization scheme was recently proposed by the authors to convert the surface wind measurements over rugged terrain into their potential values corresponding to reference conditions, that is, for neutral winds at a height of 10 m above open flat terrain (z0 = 0.03 m). As a complementary part of the preceding work, this study focuses on the standardization of surface wind speeds with marine exposures. The effect of wind strength on the roughness of the sea surface is further taken into account, with emphasis on the difference between deep-ocean and shallow-water cases. As an application example, wind measurements at a buoy site near the coastal line (water depth is 14 m) are adjusted to their potential values, which are then compared with those at a nearby station. The good agreement between the two sets of results demonstrates the accuracy and effectiveness of the standardization method. It is also found that the behavior of roughness length scale over shallow water may differ noticeably from that over deep ocean, especially under strong wind conditions, and an inappropriate usage of marine roughness predictors may result in significant estimation errors.
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Lobacheva, I., and W. Letchamo. "On the Standardization of Seabuckthorn (Hippophae rhamnoides L) Oil." HortScience 33, no. 3 (June 1998): 482a—482. http://dx.doi.org/10.21273/hortsci.33.3.482a.
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Seabuckthorn (Hippophae rhamnoides, L) (Oblepiha, Siberian pineapple, Sandorn, Sha-ji), a perennial from the Eleagnaceae family, has attracted the interest of North American natural products industry because of its effective multiple applications in cosmetic, nutriceutical, and veterinary industries. The oil obtained from the berries, bark, and leaves, and is known to contain carotenoids, vitamins, and essential fatty acids. The objective of this investigation was to elaborate and establish reliable, but inexpensive, methods in the process of standardization of the quality of oblepiha oil. Data of the phytochemical analysis of oblepiha oil obtained from various research reports and industrial and experimental sources, located in different parts of Russia (ex-USSR), were extensively investigated and statistically evaluated. An indirect method of standardization of oblepiha oil, based on the content of carotenoids and unsaponifiable fraction of the oil, has been proposed. The correlation between total carotenoids and unsaponifiable lipids in extracted oil of oblepiha (r = 0.76; P ≤ 0.05) has been shown. The strong relationship between carotenoids, unsaponifiable lipids, and sterin fractions in the raw material and industrial oil indicates the possibility of using the level of total carotenoid concentration as a reliable and direct approach to indirectly determine the efficacy of oblepiha oil for nutritional, pharmacological, and cosmetic applications.
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Reinhardt, Robert M., and B. A. Kottes Andrews. "A Vapor Transport Method for Estimating Free Formaldehyde in Solutions of Textile Chemicals." Textile Research Journal 58, no. 7 (July 1988): 409–13. http://dx.doi.org/10.1177/004051758805800706.
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A method to determine the free formaldehyde contents of solutions of textile chemicals was investigated. The amount of free formaldehyde in various solutions could be estimated quantitatively by a vapor transport method. Previous studies on vapor transport of formaldehyde to and from cotton fabrics had suggested the promise of this technique for quantification. With proper control of conditions, a direct relationship exists between free formaldehyde in a solution and that transported to cotton. The new vapor transport method eliminates much of the interference that complicates or prohibits the use of current analytical methods with solutions containing complex mixtures of textile chemicals. The study gives a description of the method, representative data obtained and their statistical correlation, and an indication of further development needed for standardization of the method.
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Chen, Chi-Shi, Chris W. Brown, and Su-Chin Lo. "Calibration Transfer from Sample Cell to Fiber-Optic Probe." Applied Spectroscopy 51, no. 5 (May 1997): 744–48. http://dx.doi.org/10.1366/0003702971940927.
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A calibration transfer method, piecewise direct standardization (PDS), was applied to a set of two-component samples measured on the same UV-visible spectrometer with the use of a cuvette cell with a 10-mm pathlength and a fiber-optic probe with a 2-mm pathlength. Piecewise direct standardization proceeds by determining a structured transformation matrix using the spectra of a few samples measured with both devices. This transformation matrix can then be used to transform any spectrum measured on one device to that obtained on another device, thereby making the calibration model transferable between devices. We used the spectra measured in a cuvette as the standard set and transferred the calibration model obtained for these spectra to spectra measured with a 2-mm fiber-optic probe on the same instrument. The total standard error of prediction (SEP) for the fiber-optic probe was 5.84 before the calibration transfer and 1.87 afterwards. Spectra were also processed by taking the Fourier transform prior to the calibration transfer. The 512 data points in each spectrum were compressed to 32 terms, starting with the first term after the dc offset. This processing reduced the background and the noise. As a consequence, in the Fourier domain, the total SEP was 5.69 before the calibration standardization and 0.79 after the calibration standardization. A calibration transfer was also performed between two fiber-optic probes; the total SEP in the spectral domain was 2.16 prior to the transfer and 1.04 after the transfer, whereas in the Fourier domain the SEP was 1.50 prior to the transfer and 0.77 after the transfer.
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Huang, Ay Huey, Jiunn Jong Wu, Yu Mei Weng, Hwia Cheng Ding, and Tsung Chain Chang. "Direct Antimicrobial Susceptibility Testing of Gram-Negative Bacilli in Blood Cultures by an Electrochemical Method." Journal of Clinical Microbiology 36, no. 10 (1998): 2882–86. http://dx.doi.org/10.1128/jcm.36.10.2882-2886.1998.
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Nonfastidious aerobic gram-negative bacilli (GNB) are commonly isolated from blood cultures. The feasibility of using an electrochemical method for direct antimicrobial susceptibility testing of GNB in positive blood cultures was evaluated. An aliquot (10 μl) of 1:10-diluted positive blood cultures containing GNB was inoculated into the Bactometer module well (bioMérieux Vitek, Hazelwood, Mo.) containing 1 ml of Mueller-Hinton broth supplemented with an antibiotic. Susceptibility tests were performed in a breakpoint broth dilution format, with the results being categorized as resistant, intermediate, or susceptible. Seven antibiotics (ampicillin, cephalothin, gentamicin, amikacin, cefamandole, cefotaxime, and ciprofloxacin) were used in this study, with each agent being tested at the two interpretive breakpoint concentrations. The inoculated modules were incubated at 35°C, and the change in impedance in each well was continuously monitored for 24 h by the Bactometer. The MICs of the seven antibiotics for each blood isolate were also determined by the standardized broth microdilution method. Of 146 positive blood cultures (1,022 microorganism-antibiotic combinations) containing GNB tested by the direct method, the rates of very major, major, and minor errors were 0, 1.1, and 2.5%, respectively. The impedance method was simple; no centrifugation, preincubation, or standardization of the inocula was required, and the susceptibility results were normally available within 3 to 6 h after inoculation. The rapid method may allow proper antimicrobial treatment almost 30 to 40 h before the results of the standard methods are available.
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Forsman, C. A., and P. Pinto da Silva. "Label-fracture of cell surfaces by replica staining." Journal of Histochemistry & Cytochemistry 36, no. 11 (November 1988): 1413–18. http://dx.doi.org/10.1177/36.11.2459187.
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We introduce replica-staining label-fracture, a method for the cytochemical mapping of membrane surfaces. This method is a corollary of the rationale of label-fracture (Pinto da Silva and Kan, 1984: J Cell Biol 99:1156). After freeze-fracture the exoplasmic halves of the membrane remain attached to the replica. We show that cytochemical labeling of cell surfaces can be performed by direct post-fracture staining of freeze-fracture replicas. This new variant of label-fracture leads to miniaturization of labeling procedures and allows standardization of labeling conditions and simultaneous processing of different specimens.
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Muenks, Carol E., Patrick G. Hogan, Carey-Ann D. Burnham, and Stephanie A. Fritz. "Comparing the Yield of Staphylococcus aureus Recovery with Static versus Agitated Broth Incubation." Journal of Pathogens 2018 (July 26, 2018): 1–3. http://dx.doi.org/10.1155/2018/1462671.
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Given the lack of standardization of methodologies for microbial recovery from built environments, we sought to compare the yield of Staphylococcus aureus with a broth enrichment method when incubated in agitated versus static conditions. Five unique strains of S. aureus at five different concentrations were cultured to compare direct plating, agitated broth enrichment, and static broth enrichment culture methods. All samples were incubated at 35° in ambient air. The lowest concentration recovered across three replicates and five strains did not differ between culture methods (Fisher’s exact test, p=0.50); notably, recovery of S. aureus was equivalent between static and agitated broth incubation. When broth enrichment was used (both static and agitated), the burden of S. aureus growth was higher (by semiquantitative assessment of 4-quadrant streaking) compared to the direct plating culture method. Optimizing strategies for microbial recovery is essential, particularly in areas of lower biomass, given the paucity of research concerning microbial communities of built environments. The results of this study, in conjunction with other experiments investigating microbiomes of built environments, can help inform protocols for standardizing culturing methods within built environments.
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Zimenkina, Natalya I., and Vladimir A. Kurkin. "Development of approaches to standardization of black walnut bark." Aspirantskiy Vestnik Povolzhiya 20, no. 1-2 (December 10, 2020): 131–36. http://dx.doi.org/10.17816/2072-2354.2020.20.1.131-136.
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Significance. Black Walnut (Juglans nigra L.) is a species of trees of the Walnut family (Juglandaceae). This plant of the genus Walnut (Juglans L.) has not been sufficiently studied unlike other species e.g. Juglans regia L. This medicinal plant raw material is quite perspective, its preparations have antimicrobial, general tonic effect. We can use its leaves, unripe fruit, and the bark. However they are not widely used in medicine. In order to introduce the plants of the Walnut genus to the State Pharmacopoeia of the Russian Federation (RF State Pharmacopoeia), it is necessary to conduct of pharmacognostic studies, to develop product specification file to confirm the identification and quality of medicinal plant raw materials.
The aim of this study is to develop a method of quantitative determination of flavonoids in the bark of the black walnut (Juglans nigra L.).
Materials and methods. Material of the study was black walnut bark, stocked during the sap flow period (April) in 2018. The bark was skived up to 15 cm long and 23 cm wide. The bark was air-dried with the protection from direct sun light. The end of the drying was checked by the brittleness of the bark.
Results. The methods of the quantitative determination of flavonoids in walnut bark has been developed. We used the differential spectrophotometry taking into consideration state standard sample of rutin at the analytical wavelength of 416 nm. The error of a single determination with a confidence level of 95% is 1.20%.
Conclusion. We used the developed technique and analyzed a number of samples of black walnut bark. The content of total flavonoids in the plant raw material is 5.13 0.02% (as calculated on rutin). The flavonoid content should be at least 4.0%.
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Konoz, Elaheh, Amir Hossein Mohsen Sarrafi, Marjaneh Samadizadeh, and Samaneh Boreiri. "Quantitative Analysis of Lorazepam in Pharmaceutical Formulation Through FTIR Spectroscopy." E-Journal of Chemistry 9, no. 4 (2012): 2232–38. http://dx.doi.org/10.1155/2012/914974.
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A Fourier transform infrared (FTIR) spectrophotometric method was development for the rapid, direct measurement of lorazepam in different pharmaceutical products. The method involves the off-line extraction of lorazepam with sonication and direct determination in the extract through peak height measurement in the 1704 cm-1using a baseline correction between 1850 and 1550 cm-1. For standardization an external calibration line established from standard solutions of lorazepam in chloroform were used. The method provides a limit of detection of 0.0030 mg per tablet (n=5), a relative standard deviation (RSD) of 2.65% for 5 independent measurement of standard solution at a concentration level of 1 mgg-1. Result obtained by FTIR agrees with those obtained by a reference methodology based on ultraviolet spectrometry and thus the developed procedure offers a good alternative for the determination of lorazepam in commercial products.
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Ceriotti, F., P. A. Bonini, M. Murone, L. Barenghi, M. Luzzana, A. Mosca, M. Ripamonti, and L. Rossi-Bernardi. "Measurement of lipase activity by a differential pH technique." Clinical Chemistry 31, no. 2 (February 1, 1985): 257–60. http://dx.doi.org/10.1093/clinchem/31.2.257.
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Abstract This is a new electrochemical method for determination of lipase activity in biological fluids, including serum, plasma, and duodenal juice. Advantages of turbidimetric methods--short reaction time, and small sample and reagent volumes--are combined with those of titrimetric methods: measurement of absolute activity (i.e., no standardization required), saturated substrate conditions, and direct measurement of reaction products. The proposed method is easy, inexpensive, and takes only 3 min. Precision is good: CV = 3.74% within day and 7.3% between days at the clinical-decision concentration, CV = 1.86% within day and 4.65% between days for above-normal lipase activities. The standard curve is linear up to 4500 U/L. Results (y) correlate well with those by turbidimetry (x): y = 0.9287x - 65.3 (r = 0.9719). Reference values are between 0 and 130 U/L.
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Mach, Vladimír, Stanislav Kotrlý, and Václav Říha. "Standardization of dilute solutions of EDTA by photometric titration with standard tetraamminecopper(II) titrant." Collection of Czechoslovak Chemical Communications 56, no. 9 (1991): 1850–55. http://dx.doi.org/10.1135/cccc19911850.
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Direct photometric titration (without an added indicator) using a standard ammoniacal solution of copper(II) prepared from pure copper metal asa primary standard is recommended as a reliable method for the standardization of Na2H2(edta) in 10-3 -5 . 10-4M solutions. The technique of photometric microtitration (720 nm, 50 mm cell) with an increased precision of transmittance reading (s ~10-2%, n > 7) and in optimum medium of pH 4.7 ± 0.4 (acetate buffer) can yield precise results in assays of EDTA (sr ⪬ 10-1%, n = 6-9).
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Thomas, Benny, K. Sankaranarayanasamy, S. Ramachandra, and SP Suresh Kumar. "Search method applied for gear tooth bending stress prediction in normal contact ratio asymmetric spur gears." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 24 (January 18, 2018): 4647–63. http://dx.doi.org/10.1177/0954406217753235.
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Various analytical methods have been developed by designers to predict gear tooth bending stress in asymmetric spur gears with an intention to improve the accuracy of predicted results and to reduce the need for time consuming finite element analysis at the early stages of gear design. Asymmetry in the drive and coast side of asymmetric spur gears poses difficulty in direct application of well-known procedures like American Gear Manufacturers Association and International Organization for Standardization in the prediction of gear tooth bending stress. In earlier works, ISO-6336-3 methodology was suitably modified and adapted to predict asymmetric spur gear tooth bending stress. This approach is based on certain assumptions on the location of critical section which could introduce error in the predicted maximum bending stress. The present work is to analytically predict gear tooth bending stress in normal contact ratio asymmetric spur gears based on a more rigorous analytical approach. This includes a fundamental study on the gear tooth orientation used to define the coordinate system, determination of maximum bending stress by search along the fillet profile and to obtain stress profile along the fillet. Gear tooth bending stress obtained from the present work using Search method is compared against the results obtained from earlier adapted International Organization for Standardization method and Finite Element Analysis. This study recommends a new coordinate system and method for analytical prediction of gear tooth bending stress in normal contact ratio asymmetric spur gears.
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Nikiforov, L. N., S. V. Krivoshchekov, N. E. Kolomiets, T. V. Kadyrova, N. V. Isaikina, N. Y. Abramets, E. A. Bezverkhniaia, and M. V. Belousov. "Development of Parameters for Standardization of Duckweed (Lemna Minor L.) Raw Material." Drug development & registration 10, no. 1 (February 25, 2021): 74–81. http://dx.doi.org/10.33380/2305-2066-2021-10-1-74-81.
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Introduction. Lemna minor L. (duckweed) refers to the duckweed subfamily (Lemnaceae S. F. Gray) and widely distributed in ponds of Russia. Literature data confirm the possibility of harvesting significant volumes of this raw material in natural habitat and grown in aquaculture. The process of biosynthetic accumulation in duckweed fronds provides a variety of compounds with a wide spectrum of biological activity. Therefore, the use of raw materials Lemna minor L. is promising for the development of drugs and parapharmaceutical products. Thus, it is an urgent task to quantify active components of duckweed and standardize (determination of criteria for identification, quality and safety) plant material.Aim. Establish macro- and microscopic characteristics of raw materials and develop methods for the quantitative determination of the main groups of biologically active substances (BAS) for standardization of raw duckweed.Materials and methods. Samples of duckweed was collected in natural habitats of Western Siberia. Macro- and microscopic assay, HPLC, UV-spectrometry were used in research process.Results and discussion. Were established the criteria for identification of duckweed fronds by studying external (macroscopic) and microscopic features of raw material Lemna minor L. Was developed and validated the procedure of the quantitative determination of phenolcarboxylic acids in raw material Lemna minor L.Conclusion. The study of external (macroscopic) and microscopic features provided the criteria for identification of the raw material Lemna minor L. The technique for the quantitative analysis of polysaccharides using gravimetry does not need validation, because is a direct method of substance measurement. Was validated quantification method of phenolcarboxylic acids (in terms of chlorogenic acid) by criteria of linearity, repeatability, in-laboratory precision and accuracy. Was established quality criteria for identification and quantitative assay, which can be used in the draft for normative documents for medicinal plant raw material of Lemna minor L. «Duckweed fronds».
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Gunaratna, P. C., W. F. Koch, R. C. Paule, A. D. Cormier, P. D'Orazio, N. Greenberg, K. M. O'Connell, A. Malenfant, A. O. Okorodudu, and R. Miller. "Frozen Human Serum Reference Material for Standardization of Sodium and Potassium Measurements in Serum or Plasma by Ion-Selective Electrode Analyzers." Clinical Chemistry 38, no. 8 (August 1, 1992): 1459–65. http://dx.doi.org/10.1093/clinchem/38.8.1459.
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Abstract Three interlaboratory round-robin studies (RR1, RR2, and RR3) were conducted to identify a serum-based reference material that would aid in the standardization of direct ion-selective electrode (ISE) measurements of sodium and potassium. Ultrafiltered frozen serum reference materials requiring no reconstitution reduced between-laboratory variability (the largest source of imprecision) more than did other reference materials. ISE values for RR3 were normalized by the use of two points at the extremes of the clinical range for sodium (i.e., 120 and 160 mmol/L), with values assigned by the flame atomic emission spectrometry (FAES) Reference Method. This FAES normalization of ISE raw values remarkably improved all sources of variability and unified the results from seven different direct ISE analyzers to the FAES Reference Method value. Subsequently, a three-tiered, fresh-frozen human serum reference material was produced to the specifications developed in RR1-RR3, was assigned certified values for sodium and potassium by Definitive Methods at the National Institute of Standards and Technology (NIST), and was made available in 1990 to the clinical laboratory community as a Standard Reference Material (SRM); it is now identified as SRM 956. Albeit retrospectively, we show how applying an FAES normalization step identical to that used in RR4/5 to the ISE data for SRM 956 after the NIST Definitive Method values were known, consistently moved the ISE results for RR3 closer to the true value for Na+ and K+.
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Herrero, Ana, and M. Cruz Ortiz. "Piecewise Direct Standardization Method Applied to the Simultaneous Determination of Pb(II), Sn(IV) and Cd(II) by Differential Pulse Polarography." Electroanalysis 10, no. 10 (August 1998): 717–21. http://dx.doi.org/10.1002/(sici)1521-4109(199808)10:10<717::aid-elan717>3.0.co;2-r.
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Smeyers-Verbeke, J., and D. Verbeelen. "Determination of aluminum in bone by atomic absorption spectroscopy." Clinical Chemistry 31, no. 7 (July 1, 1985): 1172–74. http://dx.doi.org/10.1093/clinchem/31.7.1172.
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Abstract In developing this method for determination of Al in bone we paid special attention to the homogenization of bone samples, which presents great difficulties for trace-element analysis. To minimize the risk of contamination, we preferred low-temperature ashing over classical wet-digestion techniques for destruction of the organic material. Graphite-furnace atomic absorption spectroscopy is used for measurement of Al. For Al concentrations exceeding 15 micrograms/g, direct standardization against a calibration line can be used (between-run CV, 5.9%). For Al concentrations within the normal range (less than 15 micrograms/g) the standard-addition technique should be applied. Comparison of results by the method with those by a procedure based on extraction of Al with a saturated solution of EDTA revealed that, although the latter method gave considerably lower results for three of 13 samples, there was no statistical difference between results by the two methods.
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O’Hara, Lyndsay M., Max Masnick, Surbhi Leekha, Sarah S. Jackson, Natalia Blanco, and Anthony D. Harris. "Indirect Versus Direct Standardization Methods for Reporting Healthcare-Associated Infections: An Analysis of Central Line–Associated Bloodstream Infections in Maryland." Infection Control & Hospital Epidemiology 38, no. 8 (June 19, 2017): 989–92. http://dx.doi.org/10.1017/ice.2017.120.
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Whether healthcare-associated infection data should be presented using indirect (current CMS/CDC methodology) or direct standardization remains controversial. We applied both methods to central-line–associated bloodstream infection data from 45 acute-care hospitals in Maryland from 2012 to 2014. We found that the 2 methods generate different hospital rankings with payment implications.Infect Control Hosp Epidemiol 2017;38:989–992
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Zimnickas, Tomas, Jonas Vanagas, Karolis Dambrauskas, Artūras Kalvaitis, and Mindaugas Ažubalis. "Application of Advanced Vibration Monitoring Systems and Long Short-Term Memory Networks for Brushless DC Motor Stator Fault Monitoring and Classification." Energies 13, no. 4 (February 13, 2020): 820. http://dx.doi.org/10.3390/en13040820.
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In this research, electric motors faults and their identification is reviewed. Brushless direct-current (BLDC) motors stator fault identification using long short-term memory neural networks were analyzed. A proposed method of vibration data acquisition using cloud technologies with high accuracy, feature extraction using spectral entropy, and instantaneous frequency and standardization using mean and standard deviation was reviewed. Additionally, model training with raw and standardized data was compared. A total model accuracy of 97.10 percent was achieved. The proposed methods could successfully identify the motor stator status from normal, to loss of stator winding imminent and arcing, and lastly to open circuit in stator winding—motor needing to stop immediately—by using gathered data from real experiments, training the model and testing it theoretically.
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Fusaro, Maria, Maurizio Gallieni, Maria Antonietta Rizzo, Andrea Stucchi, Pierre Delanaye, Etienne Cavalier, Rosa M. A. Moysés, et al. "Vitamin K plasma levels determination in human health." Clinical Chemistry and Laboratory Medicine (CCLM) 55, no. 6 (June 1, 2017): 789–99. http://dx.doi.org/10.1515/cclm-2016-0783.
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AbstractVitamin K (phylloquinone or vitamin K1and menaquinones or vitamin K2) plays an important role as a cofactor in the synthesis of hepatic blood coagulation proteins, but recently has also aroused an increasing interest for its action in extra-hepatic tissues, in particular in the regulation of bone and vascular metabolism. The accurate measurement of vitamin K status in humans is still a critical issue. Along with indirect assays, such as the undercarboxylated fractions of vitamin K-dependent proteins [prothrombin, osteocalcin (OC), and matrix gla protein], the direct analysis of blood levels of phylloquinone and menaquinones forms might be considered a more informative and direct method for assessing vitamin K status. Different methods for direct quantification of vitamin K serum levels are available. High-performance liquid chromatography (HPLC) methods coupled with post-column reduction procedures and fluorimetric or electrochemical detection are commonly used for food and blood analysis of phylloquinone, but they show some limitations when applied to the analysis of serum menaquinones because of interferences from triglycerides. Recent advancements include liquid chromatography tandem mass spectrometry (LCMS/MS) detection, which assures higher specificity. The optimization and standardization of these methods requires specialized laboratories. The variability of results observed in the available studies suggests the need for further investigations to obtain more accurate analytical results.
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Korobelnik, Jean-Franc¸ois, Nicholas Moore, Patrick Blin, Chandrabhan Dharmani, and Gilles Berdeaux. "Estimating the Yearly Number of Eyes with Treatable Neovascular Age-Related Macular Degeneration Using a Direct Standardization Method and a Markov Model." Investigative Opthalmology & Visual Science 47, no. 10 (October 1, 2006): 4270. http://dx.doi.org/10.1167/iovs.05-1467.
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Ignаteva, E. V., I. V. Yartseva, Z. S. Shprakh, I. R. Prosalkova, S. A. Sasov, and O. V. Orlova. "Development and Validation of Dimeric Macrocyclic Tannin Assay Method in Dosage Forms." Drug development & registration 9, no. 4 (November 26, 2020): 93–98. http://dx.doi.org/10.33380/2305-2066-2020-9-4-93-98.
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Introduction. Quantitative assessment of the active substance is necessary and perhaps the most significant part of the drug quality control. Validation of the analytical methods of quantitative assessment ensures their compliance with high requirements. The present study describes the development and validation of a spectrophotometry method for the quantitative evaluation of the active substance in the drug form of the national antitumor and antiangiogenic drug «Dimeric macrocyclic tannin (DMT) lyophilizate for solution for injection, 100 mg».Aim. The development and validation of the assay method for the standardization of «DMT lyophilizate for solution for injection, 100 mg».Materials and metods. The study used «DMT lyophilizate for solution for injection, 100 mg» and the active substance DMT. Method – spectrophotometry.Results and discussion. The methodof the quantitative assessment of the active substance in the DMT lyophilized drug by direct UV spectrophotometry was developed and the validation characteristics of the method were defined as a result of the study.Conclusion. The validation results showed that the assay method of DMT in the drug form has the appropriate accuracy, precision and linearity. The obtained results correspond to the approved criteria that allow the use of the developed methodology for evaluating the quality of the drug.
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Wang, Yongdong, and Bruce R. Kowalski. "Calibration Transfer and Measurement Stability of Near-Infrared Spectrometers." Applied Spectroscopy 46, no. 5 (May 1992): 764–71. http://dx.doi.org/10.1366/0003702924124808.
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Near-infrared (NIR) spectroscopy has been widely accepted as a quantitative technique in which multivariate calibration plays an important role. The application of NIR to process analysis, however, has been largely limited by a problem identified as calibration transfer, the attempt to transfer a well-established calibration model from one instrument (e.g., located in the central laboratory) to another instrument of the same type (e.g., located on an industrial process). A calibration transfer method called piecewise direct standardization (PDS) is applied to a set of gasoline samples measured on two different NIR spectrometers. On the basis of the measurement of a small set of transfer samples on both instruments, a structured transformation matrix can be determined and applied to transform spectra between two instruments, enabling the transfer of calibration models. The effect of spectrum preprocessing on standardization is studied with the use of a set of gasoline samples. In a separate study, the day-to-day instrument variation as observed from the change in the polystyrene spectrum is related to the prediction of moisture, oil, protein, and starch content in corn samples, and then the possibility of using such generic standards to replace real samples in a transfer set is explored. In all cases, a standard error for prediction comparable to full set cross-validation is obtained through standardization.
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Li, Li-Na, Chang-Ming Ma, Ming Chang, and Ren-Cheng Zhang. "A quick method based on SIMPLISMA-KPLS for simultaneously selecting outlier samples and informative samples for model standardization in near infrared spectroscopy." Modern Physics Letters B 31, no. 34 (December 6, 2017): 1750327. http://dx.doi.org/10.1142/s0217984917503274.
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A novel method based on SIMPLe-to-use Interactive Self-modeling Mixture Analysis (SIMPLISMA) and Kernel Partial Least Square (KPLS), named as SIMPLISMA-KPLS, is proposed in this paper for selection of outlier samples and informative samples simultaneously. It is a quick algorithm used to model standardization (or named as model transfer) in near infrared (NIR) spectroscopy. The NIR experiment data of the corn for analysis of the protein content is introduced to evaluate the proposed method. Piecewise direct standardization (PDS) is employed in model transfer. And the comparison of SIMPLISMA-PDS-KPLS and KS-PDS-KPLS is given in this research by discussion of the prediction accuracy of protein content and calculation speed of each algorithm. The conclusions include that SIMPLISMA-KPLS can be utilized as an alternative sample selection method for model transfer. Although it has similar accuracy to Kennard–Stone (KS), it is different from KS as it employs concentration information in selection program. This means that it ensures analyte information is involved in analysis, and the spectra (X) of the selected samples is interrelated with concentration (y). And it can be used for outlier sample elimination simultaneously by validation of calibration. According to the statistical data results of running time, it is clear that the sample selection process is more rapid when using KPLS. The quick algorithm of SIMPLISMA-KPLS is beneficial to improve the speed of online measurement using NIR spectroscopy.
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Concepcion, Nelydia, and Carl E. Frasch. "Evaluation of Previously Assigned Antibody Concentrations in Pneumococcal Polysaccharide Reference Serum 89SF by the Method of Cross-Standardization." Clinical Diagnostic Laboratory Immunology 5, no. 2 (March 1, 1998): 199–204. http://dx.doi.org/10.1128/cdli.5.2.199-204.1998.
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ABSTRACT An enzyme-linked immunosorbent assay (ELISA) and the antibody concentrations assigned to different pneumococcal capsular polysaccharide types were used to estimate concentrations of antibody to additional pneumococcal types in reference serum 89SF and to confirm assigned antibody values. This was possible because the slopes of curves of antibody binding to all polysaccharide types evaluated (1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, and 23F) were similar. The point estimates for total anti-pneumococcal antibody and immunoglobulin G (IgG) antibody determined by cross-standardization by an ELISA based on use of methylated human serum albumin (mHSA) to improve the efficiency of polysaccharide binding to the ELISA plate differed by less than 40% from those reported by Quataert et al. (Clin. Diagn. Lab. Immunol. 2:590–597, 1995) for types 1, 4, 6B, 7F, 9V, 14, 18C, and 23F. However, large differences were found between the assigned values and those obtained by our mHSA ELISA for types 3 and 19F. The mHSA ELISA and the direct polysaccharide coat ELISA may not measure antibodies to the same epitopes on polysaccharides of types 3 and 19F. The functional importance of these different antibody specificities is being investigated. We have thus confirmed the assigned IgG antibody values for most types by a different method and have extended antibody assignments to several additional types.
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Barbosa, Marcília Medrado, Edenio Detmann, Gabriel Cipriano Rocha, Marcia de Oliveira Franco, and Sebastião de Campos Valadares Filho. "Evaluation of Laboratory Procedures to Quantify the Neutral Detergent Fiber Content in Forage, Concentrate, and Ruminant Feces." Journal of AOAC INTERNATIONAL 98, no. 4 (July 1, 2015): 883–89. http://dx.doi.org/10.5740/jaoacint.14-156.
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Abstract A comparison was made of measurements of neutral detergent fiber concentrations obtained with AOAC Method 2002.04 and modified methods using pressurized environments or direct use of industrial heat-stable α-amylase in samples of forage (n = 37), concentrate (n = 30), and ruminant feces (n = 39). The following method modifications were tested: AOAC Method 2002.04 with replacement of the reflux apparatus with an autoclave or Ankom220® extractor and F57 filter bags, and AOAC Method 2002.04 with replacement of the standardization procedures for α-amylase by a single addition of industrial α-amylase [250 μL of Termamyl 2X 240 Kilo Novo Units (KNU)-T/g] prior to heating the neutral detergent solution. For the feces and forage samples, the results obtained with the modified methods with an autoclave or modification of α-amylase use were similar to those obtained using AOAC Method 2002.04, but the use of the Ankom220 extractor resulted in overestimated values. For the concentrate samples, the modified methods using an autoclave or Ankom220 extractor resulted in positive systematic errors. However, the method using industrial α-amylase resulted in systematic error and slope bias despite that the obtained values were close to those obtained with AOAC Method 2002.04.
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Kornum, Ditte S., Astrid J. Terkelsen, Davide Bertoli, Mette W. Klinge, Katrine L. Høyer, Huda H. A. Kufaishi, Per Borghammer, Asbjørn M. Drewes, Christina Brock, and Klaus Krogh. "Assessment of Gastrointestinal Autonomic Dysfunction: Present and Future Perspectives." Journal of Clinical Medicine 10, no. 7 (March 31, 2021): 1392. http://dx.doi.org/10.3390/jcm10071392.
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The autonomic nervous system delicately regulates the function of several target organs, including the gastrointestinal tract. Thus, nerve lesions or other nerve pathologies may cause autonomic dysfunction (AD). Some of the most common causes of AD are diabetes mellitus and α-synucleinopathies such as Parkinson’s disease. Widespread dysmotility throughout the gastrointestinal tract is a common finding in AD, but no commercially available method exists for direct verification of enteric dysfunction. Thus, assessing segmental enteric physiological function is recommended to aid diagnostics and guide treatment. Several established assessment methods exist, but disadvantages such as lack of standardization, exposure to radiation, advanced data interpretation, or high cost, limit their utility. Emerging methods, including high-resolution colonic manometry, 3D-transit, advanced imaging methods, analysis of gut biopsies, and microbiota, may all assist in the evaluation of gastroenteropathy related to AD. This review provides an overview of established and emerging assessment methods of physiological function within the gut and assessment methods of autonomic neuropathy outside the gut, especially in regards to clinical performance, strengths, and limitations for each method.
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Warnick, G. R., G. J. Boerma, G. Assmann, A. T. Endler, G. Gerique, A. M. Gotto, M. S. Graziani, U. Lippi, W. Patsch, and W. F. Riesen. "Multicenter evaluation of Reflotron direct dry-chemistry assay of high-density lipoprotein cholesterol in venous and fingerstick specimens." Clinical Chemistry 39, no. 2 (February 1, 1993): 271–77. http://dx.doi.org/10.1093/clinchem/39.2.271.
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Abstract The Reflotron HDL Cholesterol test (Boehringer Mannheim GmbH) directly separates and analyzes high-density lipoprotein (HDL) cholesterol in plasma collected with EDTA in an integrated dry-reagent system suitable for alternative site testing of lipoproteins. We describe a multicenter evaluation of this test by two US and six European laboratories experienced in lipid analysis. Each laboratory compared the Reflotron with the same conventional wet-chemistry method, Boehringer phosphotungstate-Mg2+ precipitation with enzymatic cholesterol assay. Imprecision was within accepted guidelines, with CVs of < or = 8% for fresh and frozen plasmas (median CV 1.7-3.9%) and for lyophilized sera (median CV 3.8-4.7%), similar to those of the conventional method. Results of linear-regression analysis were as follows: Reflotron HDL Cholesterol = 1.03 conventional - 3.9 mg/L, r = 0.987. The Reflotron results were somewhat low in the two US laboratories, demonstrating the need for general standardization of methods for measuring HDL cholesterol. Results from capillary fingerstick plasma agreed well with those from venous-derived plasma; capillary = 1.04 venous + 4.5 mg/L, r = 0.967. The system is relatively insensitive to interference from hemoglobin (< or = 0.75 g/L), ascorbic acid (< or = 0.3 g/L), bilirubin (< or = 50 mg/L), cholesterol (< or = 3.5 g/L), and triglycerides (< or = 4 g/L). The relative ease of operation and the rapid availability of results (within 90 s for plasma collected in EDTA) make the method appropriate for use by well-trained, but not necessarily technical, operators in the physician's office or other alternative sites.
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Osaki, Silvia Cristina, Adriana Oliveira Costa, Ludmilla Della Coletta Troiano, Ernesto Renato Kruger, Juliana Tracz Pereira, Nelson Luis Mello Fernandes, Márcia Benedita de Oliveira Silva, and Vanete Thomaz Soccol. "Production of anti-Cryptosporidium polyclonal antibodies and standardization of direct immunofluorescence for detecting oocysts in water." Revista da Sociedade Brasileira de Medicina Tropical 44, no. 5 (October 2011): 587–90. http://dx.doi.org/10.1590/s0037-86822011000500011.
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INTRODUCTION: The production of anti-Cryptosporidium polyclonal antibodies and its use in direct immunofluorescence assays to determine the presence of Cryptosporidium in water are described in the present work. METHODS: Two rabbits were immunized with soluble and particulate antigens from purified Cryptosporidium oocysts. The sera produced were prepared for immunoglobulin G extraction, which were then purified and conjugated with fluorescein isothiocyanate (FITC). Slides containing known amounts of oocysts were prepared to determine the sensitivity of the technique. To test the specificity, slides containing Giardia duodenalis cysts were prepared. RESULTS: The conjugate was successfully used in water samples experimentally contaminated with Cryptosporidium oocysts, and it was possible to detect up to five oocysts/spot, corresponding to contamination of 250 oocysts/mL. CONCLUSIONS: The three immunizations performed in the rabbits were enough to produce antibodies against Cryptosporidium, the standard direct immunofluorescence assay permitted the detection of five oocysts in 20% of the samples, and no cross-reaction with Giardia duodenalis cysts occurred.
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Modur, Vi j. ay, Dean C. Bottino, Susan Branford, Tillmann Krahnke, Fabrizio Pane, Marc Rudoltz, Yu Jin, et al. "Mathematical Simulation of BCR-ABL Real Time Quantitative Polymerase Chain Reaction (RQ-PCR) for Chronic Myeloid Leukemia (CML) Response Monitoring Provides Insight on the Basis of International Standardization." Blood 112, no. 11 (November 16, 2008): 2124. http://dx.doi.org/10.1182/blood.v112.11.2124.2124.
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Abstract BACKGROUND: Cytogenetic assessment to measure CML response to Glivec or Tasigna is expressed as a ratio of Ph+ CML to total cells. Molecular response determination for CML by RQ-PCR achieves a similar goal by obtaining a ratio of transcript levels of BCR-ABL expressed exclusively in Ph+ CML cells to the BCR or ABL control gene which is expressed in both Ph+ and normal cells. However when a RQ-PCR assay result is obtained, a different RQ-PCR ratio will be obtained for the same sample using BCR vs. ABL as control gene due to the intrinsic expression level differences in the two control genes. Experiments have demonstrated empirically that international standardization of RQ-PCR data obtained by assays using these different control genes is possible, thus allowing direct comparison of data. We have developed a mathematical simulation that explains the underlying basis for international standardization and this was experimentally confirmed to show how standardization is feasible in practice as a part of the Tyrosine Kinase Optimization and Selectivity (TOPS) trial. METHODS: We have mathematically simulated a correlation between theoretical cytogenetic response (Ph+ to total cell ratio) with the theoretical molecular response (BCR-ABL to control gene transcript ratio) by using the following assumptions; 1) BCR and BCR-ABL expression occur from similar promoters and likely have similar expression levels. 2) Ph+ cells have one normal BCR resulting in 1x level of BCR transcription and normal cells have two normal copies of BCR resulting in 2x level of BCR transcription (x=BCR transcription rate from one promoter). This simulation was extended to the ABL control gene as data of the relative expression level of ABL vs. BCR was available from samples in the TOPS trial, and the ABL transcript level is similar in both Ph+ and normal cells as the ABL PCR primers amplify both ABL and BCR-ABL transcripts. To experimentally test the simulation, RQ-PCR samples from patients in TOPS were exchanged between the study’s regional RQ-PCR laboratories. Each sample was assayed at 2 labs, one using BCR and the other ABL as the control gene. RESULTS: Mathematical simulation suggests that RQ-PCR ratios with BCR but not ABL as control gene has a nonlinear relationship with the Ph+ to the total cell ratio across the entire range from 0 to 100%. However at clinically relevant RQ-PCR ratio of ≤10%, irrespective of whether BCR or ABL is used as a control gene, RQ-PCR ratios are linear but with different slopes due to higher ratios obtained with ABL as control gene. Despite the different slopes, RQ-PCR ratios obtained with either control gene can be easily inter-converted via a multiplicative factor to neutralize the bias between methods as is currently recommended in international standardization. Experimental testing in the TOPS trial showed that; 1) ABL transcript copy number is significantly lower than BCR transcript copy number leading to higher RQ-PCR ratios with ABL as control gene. 2) Mathematical correction of bias between BCR and ABL as control gene allows for direct comparison of RQ-PCR ratios with an 88.2% concordance when ratios are below 10%. CONCLUSIONS: Mathematical simulation shows that for BCR and ABL as the control gene, the basis for international standardization is a consistent linear relationship that can be easily inter-converted when PCR ratios are ≤ 10%. This can be experimentally demonstrated by the high level of concordance obtained when the same sample is analyzed using different control genes. For RQ-PCR ratios > 10%, standardization is not possible using the currently applied neutralization of bias method of conversion, but may be possible by using a formula that accounts for the non-linear relationship of BCR as a control gene. Simulation studies also highlight the importance of not only obtaining precise but also accurate RQ-PCR ratios thus enabling consistent standardization.