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Pflüger M, Brunner D, Heuser T, Lott JA, Reitzenstein S, Fischer I. Experimental reservoir computing with diffractively coupled VCSELs. Opt Lett 2024; 49:2285-2288. [PMID: 38691700 DOI: 10.1364/ol.518946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 03/19/2024] [Indexed: 05/03/2024]
Abstract
We present experiments on reservoir computing (RC) using a network of vertical-cavity surface-emitting lasers (VCSELs) that we diffractively couple via an external cavity. Our optical reservoir computer consists of 24 physical VCSEL nodes. We evaluate the system's memory and solve the 2-bit XOR task and the 3-bit header recognition (HR) task with bit error ratios (BERs) below 1% and the 2-bit digital-to-analog conversion (DAC) task with a root mean square error (RMSE) of 0.067.
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Pflüger M, Brunner D, Heuser T, Lott JA, Reitzenstein S, Fischer I. Injection locking and coupling the emitters of large VCSEL arrays via diffraction in an external cavity. Opt Express 2023; 31:8704-8713. [PMID: 36859980 DOI: 10.1364/oe.473449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 12/08/2022] [Indexed: 06/18/2023]
Abstract
Networks of semiconductor lasers are the foundation of numerous applications and fundamental investigations in nonlinear dynamics, material processing, lighting, and information processing. However, making the usually narrowband semiconductor lasers within the network interact requires both high spectral homogeneity and a fitting coupling concept. Here, we report how we use diffractive optics in an external cavity to experimentally couple vertical-cavity surface-emitting lasers (VCSELs) in a 5×5 array. Out of the 25 lasers, we succeed to spectrally align 22, all of which we lock simultaneously to an external drive laser. Furthermore, we show the considerable coupling interactions between the lasers of the array. This way, we present the largest network of optically coupled semiconductor lasers reported so far and the first detailed characterization of such a diffractively coupled system. Due to the high homogeneity of the lasers, the strong interaction between them, and the scalability of the coupling approach, our VCSEL network is a promising platform for experimental investigations of complex systems, and it has direct applications as a photonic neural network.
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Komar P, Gębski M, Lott JA, Wasiak M. Chromatic aberration in planar focusing mirrors based on a monolithic high contrast grating. Opt Express 2021; 29:30296-30306. [PMID: 34614755 DOI: 10.1364/oe.433813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
We present an experimental and theoretical analysis of chromatic aberration in a monolithic metasurface focusing mirror. The planar focusing mirror is based on a monolithic high contrast grating made from GaAs, designed for a wavelength of 980 nm. Light is focused on the high refractive index side of the mirror. Our measurements, performed between 890 and 1050 nm, indicate a shift of the focal point position that is inversely proportional to the wavelength. The experimental results are in very good agreement with our simulations, in terms of both the position of the focal point and the spectral dependence. Based on our numerical simulations, we show that simply modifying the grating height does not lead to significant alteration of the focal length or to any noticeable reduction in chromatic aberration. Using numerical simulations, we analyze how the height of the stripes, the refractive index of the grating material, and its dispersion combine to influence the chromatic aberration of the mirror.
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Komar P, Gȩbski M, Lott JA, Czyszanowski T, Wasiak M. Experimental Demonstration of Light Focusing Enabled by Monolithic High-Contrast Grating Mirrors. ACS Appl Mater Interfaces 2021; 13:25533-25539. [PMID: 34008943 PMCID: PMC8289169 DOI: 10.1021/acsami.1c04871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 05/06/2021] [Indexed: 06/12/2023]
Abstract
We present the first experimental demonstration of a planar focusing monolithic subwavelength grating mirror. The grating is formed on the surface of GaAs and focuses 980 nm light in one dimension on the high-refractive-index side of the mirror. According to our measurements, the focal length is 475 μm (300 μm of which is GaAs) and the numerical aperture is 0.52. The intensity of the light at the focal point is 23 times larger than that of the incident light. To the best of our knowledge, this is the highest value reported for a grating mirror. Moreover, the full width at half-maximum (FWHM) at the focal point is only 3.9 μm, which is the smallest reported value for a grating mirror. All of the measured parameters are close to or very close to the theoretically predicted values. Our realization of a sophisticated design of a focusing monolithic subwavelength grating opens a new avenue to technologically simple fabrication of the gratings for use in diverse optoelectronic materials and applications.
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Affiliation(s)
- Paulina Komar
- Institute
of Physics, Lodz University of Technology, Wólczańska 219, 90-924 Łódź, Poland
| | - Marcin Gȩbski
- Institute
of Physics, Lodz University of Technology, Wólczańska 219, 90-924 Łódź, Poland
- Institute
of Solid State Physics and Center of Nanophotonics, Technical University Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - James A. Lott
- Institute
of Solid State Physics and Center of Nanophotonics, Technical University Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
| | - Tomasz Czyszanowski
- Institute
of Physics, Lodz University of Technology, Wólczańska 219, 90-924 Łódź, Poland
| | - Michał Wasiak
- Institute
of Physics, Lodz University of Technology, Wólczańska 219, 90-924 Łódź, Poland
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Marciniak M, Broda A, Gębski M, Dems M, Muszalski J, Czerwinski A, Ratajczak J, Marona Ł, Nakwaski W, Lott JA, Czyszanowski T. Tuning of reflection spectrum of a monolithic high-contrast grating by variation of its spatial dimensions. Opt Express 2020; 28:20967-20977. [PMID: 32680146 DOI: 10.1364/oe.396693] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 05/30/2020] [Indexed: 06/11/2023]
Abstract
We report the first experimental parametric analysis of subwavelength monolithic high-contrast grating (MHCG) mirrors. To date, subwavelength grating mirrors have been fabricated by suspending a thin grating membrane in the air or placing it on a low refractive index material - a scheme that requires sophisticated processing and makes the gratings sensitive to mechanical stress, impeding current injection, and heat dissipation if used in active devices. Inherently MHCGs are well suited for optoelectronic devices because they can be fabricated in all possible material systems. Here we demonstrate above 90% optical power reflectance, strong polarization discrimination. Based on experimental analysis aided by numerical simulations, we demonstrate the possibility of tuning the spectral characteristics of MHCGs reflectance for more than 200 nm via modification of the duty cycle of the MHCG stripes. We show our MHCG tuning method is convenient to define the properties of MHCG devices during the device processing.
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Gębski M, Lott JA, Czyszanowski T. Electrically injected VCSEL with a composite DBR and MHCG reflector. Opt Express 2019; 27:7139-7146. [PMID: 30876284 DOI: 10.1364/oe.27.007139] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 11/21/2018] [Indexed: 06/09/2023]
Abstract
We achieve the continuous-wave (CW) lasing of electrically-injected, first-of-their-kind vertical-cavity surface-emitting lasers (VCSELs) that use a subwavelength monolithic high-refractive-index-contrast grating (MHCG) mirror. The MHCG, unlike the well-known high-refractive-index-contrast grating (HCG) is neither a membrane suspended in the air nor a structure that requires a cladding layer. The MHCG is patterned in a semiconductor material atop the VCSEL cavity creating an all-semiconductor laser. Static measurements show CW operation of the VCSELs from room temperature up to 75 °C. The VCSEL with a 13.5 μm current oxide aperture diameter operates with quasi-single mode emission from threshold to rollover. Our results open a way to produce all-semiconductor surface emitting lasers emitting at wavelengths from the ultraviolet and the visible (GaN-based) to the infrared (InP- and GaSb-based) with a reduced vertical thickness and thus we believe the manufacturing costs potentially will be reduced by approximately up to about 90% in comparison to the typical DBR VCSELs. Our VCSELs have immediate and emerging applications in optical communication, illumination, sensing, and as light sources in photonic integrated circuits.
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Marciniak M, Gębski M, Dems M, Haglund E, Larsson A, Riaziat M, Lott JA, Czyszanowski T. Optimal parameters of monolithic high-contrast grating mirrors. Opt Lett 2016; 41:3495-3498. [PMID: 27472602 DOI: 10.1364/ol.41.003495] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this Letter a fully vectorial numerical model is used to search for the construction parameters of monolithic high-contrast grating (MHCG) mirrors providing maximal power reflectance. We determine the design parameters of highly reflecting MHCG mirrors where the etching depth of the stripes is less than two wavelengths in free space. We analyze MHCGs in a broad range of real refractive index values corresponding to most of the common optoelectronic materials in use today. Our results comprise a complete image of possible highly reflecting MHCG mirror constructions for potential use in optoelectronic devices and systems. We support the numerical analysis by experimental verification of the high reflectance via a GaAs MHCG designed for a wavelength of 980 nm.
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Siskaninetz WJ, Ehret JE, Albrecht JD, Bedford RG, Nelson TR, Lott JA. Gigahertz modulation of GaAs-based bipolar cascade vertical cavity surface-emitting lasers. Opt Lett 2007; 32:136-8. [PMID: 17186042 DOI: 10.1364/ol.32.000136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The high-frequency modulation characteristics of GaAs-based bipolar cascade vertical cavity surface-emitting lasers operating at 980 nm with GaAs tunnel junctions and p-doped Al0.98Ga0.02As oxide apertures have been measured. We achieve -3 dB laser output modulations of 6.5 GHz for two-stage and 9.4 GHz for three-stage devices in response to small-signal current injection at an operating temperature of -50 degrees C.
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Affiliation(s)
- W J Siskaninetz
- Air Force Research Laboratory and Electrical and Computer Engineering Department, Air Force Institute of Technology, Wright-Patterson Air Force Base, OH 45433, USA
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Wallace JF, Pugia MJ, Lott JA, Luke KE, Shihabi ZK, Sheehan M, Bucksa JM. Multisite evaluation of a new dipstick for albumin, protein, and creatinine. J Clin Lab Anal 2001; 15:231-5. [PMID: 11574949 PMCID: PMC6807974 DOI: 10.1002/jcla.1032] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The goal of our study was to perform a multisite evaluation of a new urine dipstick called Multistix PROtrade mark (Bayer, Elkhart, IN), which has reagent pads for the simultaneous assay of urinary albumin, protein, and creatinine. Patients' urine specimens were assayed at four sites with these dipsticks and with the familiar Bayer Multistix 10SG dipsticks for protein. The new dipstick pads for albumin are impregnated with bis (3',3"-diiodo-4',4"-dihydroxy-5',5"-dinitrophenyl)-3,4,5,6-tetrabromo-sulfonephthalein (DIDNTB) dye. These dipsticks also have a novel pad that estimates urinary creatinine using the peroxidase activity of the copper-creatinine complex. We determined the interlaboratory agreement of these dipsticks by comparing dipstick results to values obtained by quantitative analytical methods. We found that dividing the dipsticks' albumin or protein results by the creatinine concentration reduced the number of false-positive albumin or protein values observed in concentrated urines, and reduced the number of false negatives in dilute urines. The ratio of albumin to creatinine, or protein to creatinine gives a better measure of albumin or protein excretion. Compared to reading by eye, the dipstick results agreed better with the quantitative assays when they were read by a reflectometer (Bayer Clinitek).
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Affiliation(s)
- J F Wallace
- Diagnostics Business Group, Bayer Corporation, Elkhart, Indiana 46530, USA
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Dufour DR, Lott JA, Nolte FS, Gretch DR, Koff RS, Seeff LB. Diagnosis and monitoring of hepatic injury. II. Recommendations for use of laboratory tests in screening, diagnosis, and monitoring. Clin Chem 2001. [PMID: 11106350 PMCID: PMC7110382 DOI: 10.1093/clinchem/46.12.2050] [Citation(s) in RCA: 207] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Purpose: To review information on the use of laboratory tests in screening, diagnosis, and monitoring of acute and chronic hepatic injury. Data Sources and Study Selection: A MEDLINE search was performed for key words related to hepatic diseases, including acute hepatitis, chronic hepatitis, alcoholic hepatitis, cirrhosis, hepatocellular carcinoma, and etiologic causes. Abstracts were reviewed, and articles discussing use of laboratory tests selected for review. Additional articles were selected from the references. Guideline Preparation and Review: Drafts of the guidelines were posted on the Internet, presented at the AACC Annual Meeting in 1999, and reviewed by experts. Areas requiring further amplification or literature review were identified for further analysis. Specific recommendations were made based on analysis of published data and evaluated for strength of evidence and clinical impact. Recommendations: Although many specific recommendations are made in the guidelines, only some summary recommendations are listed here. In acute hepatic injury, prothrombin time and, to a lesser extent, total bilirubin are the best indicators of severity of disease. Although ALT is useful for detecting acute and chronic hepatic injury, it is not related to severity of acute hepatic injury and only weakly related to severity of chronic hepatic injury. Specific tests of viral markers should be the initial differential tests in both acute and chronic hepatic injury; when positive, they are also useful for monitoring recovery from hepatitis B and C.
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Affiliation(s)
- D R Dufour
- Pathology and Laboratory Medicine Service, Veterans Affairs Medical Center, Washington, DC 20422, USA.
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Dufour DR, Lott JA, Nolte FS, Gretch DR, Koff RS, Seeff LB. Diagnosis and monitoring of hepatic injury. II. Recommendations for use of laboratory tests in screening, diagnosis, and monitoring. Clin Chem 2000; 46:2050-68. [PMID: 11106350 PMCID: PMC7110382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
PURPOSE To review information on the use of laboratory tests in screening, diagnosis, and monitoring of acute and chronic hepatic injury. DATA SOURCES AND STUDY SELECTION A MEDLINE search was performed for key words related to hepatic diseases, including acute hepatitis, chronic hepatitis, alcoholic hepatitis, cirrhosis, hepatocellular carcinoma, and etiologic causes. Abstracts were reviewed, and articles discussing use of laboratory tests selected for review. Additional articles were selected from the references. Guideline Preparation and Review: Drafts of the guidelines were posted on the Internet, presented at the AACC Annual Meeting in 1999, and reviewed by experts. Areas requiring further amplification or literature review were identified for further analysis. Specific recommendations were made based on analysis of published data and evaluated for strength of evidence and clinical impact. RECOMMENDATIONS Although many specific recommendations are made in the guidelines, only some summary recommendations are listed here. In acute hepatic injury, prothrombin time and, to a lesser extent, total bilirubin are the best indicators of severity of disease. Although ALT is useful for detecting acute and chronic hepatic injury, it is not related to severity of acute hepatic injury and only weakly related to severity of chronic hepatic injury. Specific tests of viral markers should be the initial differential tests in both acute and chronic hepatic injury; when positive, they are also useful for monitoring recovery from hepatitis B and C.
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Affiliation(s)
- D R Dufour
- Pathology and Laboratory Medicine Service, Veterans Affairs Medical Center, Washington, DC 20422, USA.
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Taes YE, Louagie H, Yvergneaux JP, De Buyzere ML, De Puydt H, Delanghe JR, Lott JA. Prolonged hyperlipasemia attributable to a novel type of macrolipase. Clin Chem 2000; 46:2008-13. [PMID: 11106339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
BACKGROUND We present the case of an 80-year-old woman who was admitted to hospital with an intermittent volvulus of the right colon. A total colectomy was performed. Initially, serum amylase and lipase increased concordantly, but after a few weeks amylase normalized (85 U/L), whereas lipase increased to 3764 U/L. This discrepancy and persistence of hyperlipasemia suggested a macromolecular form of lipase. METHODS The nature of the macromolecular complex was studied using high-pressure liquid gel-permeation chromatography, affinity chromatography, (immuno)electrophoresis, and immunodiffusion. RESULTS Gel-permeation chromatography revealed a macrolipase, with a molecular mass >900 kDa, that contributed up to 56% of total serum lipase activity. Butanol extraction of the specimen did not alter the elution profile. The thermostabilities of pancreatic lipase and the macroform were similar, whereas activation energy (E:(a)) was lower in the macromolecular lipase (28 +/- 4 kJ. mol(-1). K(-1) vs 48 +/- 7 kJ. mol(-1). K(-1) (P: = 0.02). Agarose electrophoresis showed a broad band of lipase activity at the application site. Protein A-Sepharose affinity gel chromatography excluded IgG-linked lipase. Agarose electrophoresis and immunofixation excluded linkage to other immunoglobulins. Radial immunodiffusion did not show lipase activity in the immunoglobulin precipitation bands. Radial immunodiffusion with alpha(2)-macroglobulin (alpha(2)-MG) antibodies showed a diffuse spot of lipase activity within the precipitation band, suggesting a macromolecular association between lipase and alpha(2)-MG. Affinity gel chromatography against alpha(2)-MG showed lipase activity in the alpha(2)-MG-bound fractions. CONCLUSION This is the first report of a macrolipase in which an association between alpha(2)-MG and lipase is described.
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Affiliation(s)
- Y E Taes
- Department of Clinical Chemistry, University Hospital Ghent, De Pintelaan 185, 9000 Ghent, Belgium. General Hospital St.-Lucas, 9000 Ghent, Belgium
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Dufour DR, Lott JA, Nolte FS, Gretch DR, Koff RS, Seeff LB. Diagnosis and monitoring of hepatic injury. I. Performance characteristics of laboratory tests. Clin Chem 2000; 46:2027-49. [PMID: 11106349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
PURPOSE To review information on performance characteristics for tests that are commonly used to identify acute and chronic hepatic injury. DATA SOURCES AND STUDY SELECTION A MEDLINE search was performed for key words related to hepatic tests, including quality specifications, aminotransferases, alkaline phosphatase, gamma-glutamyltransferase, bilirubin, albumin, ammonia, and viral markers. Abstracts were reviewed, and articles discussing performance of laboratory tests were selected for review. Additional articles were selected from the references. Guideline Preparation and Review: Drafts of the guidelines were posted on the Internet, presented at the AACC Annual Meeting in 1999, and reviewed by experts. Areas requiring further amplification or literature review were identified for further analysis. Specific recommendations were made based on analysis of published data and evaluated for strength of evidence and clinical impact. The drafts were also reviewed by the Practice Guidelines Committee of the American Association for the Study of Liver Diseases and approved by the committee and the Association's Council. RECOMMENDATIONS Although many specific recommendations are made in the guidelines, some summary recommendations are discussed here. Alanine aminotransferase is the most important test for recognition of acute and chronic hepatic injury. Performance goals should aim for total error of <10% at the upper reference limit to meet clinical needs in monitoring patients with chronic hepatic injury. Laboratories should have age-adjusted reference limits for enzymes in children, and gender-adjusted reference limits for aminotransferases, gamma-glutamyltransferase, and total bilirubin in adults. The international normalized ratio should not be the sole method for reporting results of prothrombin time in liver disease; additional research is needed to determine the reporting mechanism that best correlates with functional impairment. Harmonization is needed for alanine aminotransferase activity, and improved standardization for hepatitis C viral RNA measurements.
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Affiliation(s)
- D R Dufour
- Pathology and Laboratory Medicine Service, Veterans Affairs Medical Center, Washington, DC 20422, USA.
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Pugia MJ, Murakami M, Lott JA, Ohta Y, Kitagawa T, Yamauchi K, Suhara Y, Kasjima J. Screening for proteinuria in Japanese schoolchildren: a new approach. Clin Chem Lab Med 2000; 38:975-82. [PMID: 11140632 DOI: 10.1515/cclm.2000.145] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
By governmental mandate, Japanese school children are screened annually for proteinuria, hematuria, and glucosuria to identify children with possible renal disorders. We added urine dipstick tests for albumin and creatinine to the Japanese screening protocol, and used their dipstick results for blood, glucose and protein. The sulfosalicylic acid precipitation test was used to confirm "trace" positive protein dipsticks. The Japanese and our screening protocol have in common the same data for glucosuria and proteinuria. Their scheme has an algorithm for repeat testing of children with abnormal results, and further testing and medical evaluation for those showing persistently abnormal values. Out of the 23,121 students, we found seven with likely nephritis, one with confirmed nephritis, one with nephrotic syndrome, 170 with persistent unexplained hematuria, 19 with persistent unexplained proteinuria, 14 cases of urinary tract infection, and 20 cases of likely diabetes mellitus. We conclude that dipstick testing for albumin, protein, creatinine, glucose and occult blood has significant value in a multilevel testing scheme for identifying children with urinary tract abnormalities or diabetes. The assay of albumin increases the sensitivity of the screening, and dividing the albumin by the creatinine concentration reduces the potential errors arising from concentrated or dilute urines.
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Affiliation(s)
- M J Pugia
- Diagnostics Business Group, Bayer Corporation, Elkhart, IN, USA
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Abstract
We developed a dye-binding method for albumin in urine based on bis (3',3"-diiodo4'4"-dihydroxy-5'5"-dinitrophenyl)-3,4,5,6-tetrabr omosulfonphthalein (DIDNTB), a dye that has a higher chemical sensitivity and specificity for albumin when compared to two other commonly used dyes. We prepared urine dipsticks with DIDNTB and certain other compounds to prevent "nonspecific" binding to the dipstick matrix. The detection limit for albumin with DIDNTB as the dye is about 10 mg/L. The extent of dye binding to proteins and other compounds was studied using ultracentrifugation and a selectively permeable membrane that permitted the passage of free but not bound dye; we believe this method is superior to photometric titration. The affinity of the dyes for albumin was found to be pH dependent with stronger binding at pH 1.8 than at pH 7.0. At pH 1.8, DIDNTB had a ca.10-fold greater binding coefficient to albumin when compared to the widely used dyes, tetrabromophenol blue (CI 4430-25-5) or bromophenol blue (CI 115-39-9). We developed a system that minimized nonspecific binding by the dye through the use of polymethyl vinyl ethers and bis-(heptapropylene glycol) carbonate. DIDNTB showed a greater chemical specificity for albumin when compared to most other proteins. The new albumin dipsticks are resistant to many potential interferences at substantial concentrations, making the dipsticks suitable to screen for albuminuria.
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Affiliation(s)
- M J Pugia
- Diagnostics Business Group, Bayer Corporation, Elkhart, Indiana
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Pugia MJ, Lott JA, Luke KE, Shihabi ZK, Wians FH, Phillips L. Comparison of instrument-read dipsticks for albumin and creatinine in urine with visual results and quantitative methods. J Clin Lab Anal 2000. [PMID: 9773958 DOI: 10.1002/(sici)1098-2825(1998)12:5<280::aid-jcla5>3.0.co;2-a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
Three hospital sites evaluated the Bayer two-pad urine dipstick as a screening test for microalbuminuria. One pad estimates albumin concentrations between 10 and 150 mg/L, and the second estimates creatinine values between 300 and 3,000 mg/L. The Boehringer Mannheim (BMD) Micral dipstick was also compared and evaluated. The accuracy of the dipsticks was judged by comparison with cuvet-based immunonephelometry for albumin and to standard rate-Jaffe methods for creatinine; these assays were well standardized and controlled and were assumed to give accurate values. Precision of these methods and that of the dipsticks was determined by multiple assays of control materials. Visual or instrument (Clinitek 50 or 100) evaluation of the Bayer or visual checks of the BMD albumin dipstick pad with patients' urines gave clinically acceptable accuracy. The albumin/creatinine ratio from the Bayer dipsticks gave better accuracy for albumin excretion than the albumin pads alone from either manufacturer. This ratio should permit making a good estimate of the 24-hr albumin excretion in a randomly collected urine.
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Affiliation(s)
- M J Pugia
- Diagnostics Business Group, Bayer Corporation, Elkhart, Indiana, USA
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Abstract
Timed urine collections are difficult to use in clinical practice owing to inaccurate collections making calculations of the 24-h albumin or protein excretion questionable. One of our goals was to assess the 'correction' of urinary albumin and (or) protein excretion by dividing these by either the creatinine concentration or the term, (specific gravity-1)x100(1). The 24-h creatinine excretion can be estimated based on the patients' gender, age and weight. We studied the influence of physiological extremes of hydration and exercise, and protein and creatinine excretion in patients with or suspected kidney disorders. Specimens were collected from healthy volunteers every 4 h during one 24-h period. We assayed the collections individually to give us an assessment of the variability of the analytes with time, and then reassayed them after combining them to give a 24-h urine. For all volunteers, the mean intra-individual CVs based on the 4-h collections expressed in mg/24 h were 80.0% for albumin and 96.5% for total protein (P0.2). The CVs were reduced by dividing the albumin or protein concentration by the creatinine concentration or by the term, (SG-1)x100. This gave a CV for mg albumin/g creatinine of 52% (P<0.1 vs. albumin mg/g creatinine); mg protein/g creatinine of 39% (P<0.05 vs. mg protein/g creatinine); mg albumin/[(SG-1)x100] of 49% (P<0.1 vs. albumin)/[(SG-1)x100]; and mg protein/[(SG-1)x100] of 37% (P<0. 05 vs. mg protein)/[(SG-1)x100]. For the 68 subjects in the study, the strongest correlation was between the creatinine concentrations and the 24-h urine volume: r=0.786, P<0.001. The correlation of (SG-1)x100 vs. the 24-h urine volume was: r=0.606, P<0.001; for (SG-1)x100 and the creatinine concentration, the correlation was: r=0.666, P<0.001. Compared to the volunteers, the albumin and protein excretion in mg/24 h were more variable in the patients. The same was true if the albumin or protein concentrations were divided by the creatinine concentration or by (SG-1)x100. Protein and albumin concentrations were lower in dilute urines. Dividing the albumin or protein concentrations by the creatinine concentration reduced the number of false negative protein and albumin results. Dividing the albumin or protein values in mg/24 h by (SG-1)x100 eliminated fewer false negatives. Albumin concentrations increased significantly after vigorous exercise. The increase was almost eliminated when the albumin result was divided by the creatinine concentration suggesting that a decreased urine flow and not increased glomerular permeability causes an increase of post-exercise albuminuria. The same was true for proteinuria. A dipstick test plus an optical strip reader that can measure urine protein, albumin, and creatinine and calculate the appropriate ratios provides a better screening test for albuminuria or proteinuria than one measuring only albumin or protein.
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Affiliation(s)
- D J Newman
- SW Thames Institute for Renal Research, St. Helier Hospital, Wrythe Lane, Carshalton, Surrey, UK
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19
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Abstract
We have made great strides in understanding the pathophysiology and medical management of hypertension, yet barriers to effective blood pressure control remain. The process of identifying the barriers within the health care system may be as important as the barriers themselves. Our primary purpose was to apply the widely accepted tool, Continuous Quality Improvement (CQI), to identify barriers to the management of hypertension. We wanted to identify the most important factors and (or) persons in effective blood pressure control and to compare costs, satisfaction, and blood pressure control among subgroups of patients to identify those most likely to benefit from interventions. We recruited patients with essential hypertension who came to a university-based clinic staffed by family physicians and residents; 181 patients with hypertension were identified and asked at the time of their visit to complete a questionnaire relating to the management of their blood pressure. Twenty-five physicians and 8 medical assistants were also asked to complete a similar questionnaire regarding their perceptions of barriers to blood pressure management. All other information came from the patients' medical records. Blood pressure control was based on a reading taken on the date the questionnaire was completed. Student's t test was used to determine if statistically significant differences existed in blood pressure control, patient satisfaction, and total costs for certain subgroups; regression analysis was used to determine correlations. We had completed questionnaires from 91 patients, 89 physicians, and 79 staff. The physicians and staff were of course involved; however, we found that the patients' gestalt was extremely important in blood pressure control. Our patients perceived that lifestyle modifications such as exercise and weight loss were the greatest barrier to better blood pressure control. The cost of certain antihypertensive drugs was an obstacle for some patients. African Americans had poorer blood pressure control, and their satisfaction of care was significantly lower than that of other races. Our patients taught us that the 2 major barriers to blood pressure control were changes in lifestyle and reducing the cost of medications. We also found that our African American patients showed the poorest blood pressure control and the greatest dissatisfaction with their care. We surmise that the greatest benefit of any intervention would be expected in this population. We demonstrated that CQI can be used to identify barriers to hypertension management and subgroups of patients likely to benefit from interventions.
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Affiliation(s)
- M T Coleman
- Department of Family and Community Medicine, University of Louisville, KY 42092, USA.
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20
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Abstract
OBJECTIVES It was our goal to develop a urine dipstick that could measure creatinine with a peroxidase reaction. The simultaneous measurement of albumin and creatinine permits the estimation of the 24-h albumin excretion, an important value in judging existing or likely development of renal failure. A highly sensitive dye-binding dipstick method for albumin exists, and a suitable dipstick for the assay for urine creatinine is described here. METHODS Copper-creatinine and iron-creatinine complexes have peroxidase activity. With 3,3',5,5'-tetramethylbenzidine (TMB), and diisopropyl benzene dihydroperoxide (DBDH); the peroxidase activity of copper-creatinine and iron-creatinine complexes can be demonstrated. This reaction was used in the assay of urine creatinine either in solution or by a suitably impregnated urine dipstick. RESULTS Our method based on the peroxidase activity of the copper-creatinine complex has an analytical range for creatinine of 100 mg/L (0.884 mmol/L) to 3000 mg/L (26.52 mmol/L). The creatinine assay is free from most interfering compounds that may be present in urine. Hemoglobin is an interferent, and its effects can be reduced but not eliminated by the addition of 4-hydroxy-2-methyl quinoline. We do not recommend using the dipsticks when visible blood is present or if the dipstick blood test is positive. The copper-creatinine complex oxidizes ascorbic acid; however, we were able to modify the reaction conditions so that ascorbic acid at < 4.4 g/L does not interfere. We found good agreement on fresh urines between the creatinine dipstick results and those by a standard rate-Jaffe cuvet method for creatinine. DISCUSSION With the simultaneous measurement of creatinine and albumin in urine, the albumin/creatinine ratio can be determined effectively reducing or eliminating the occasional false-negative and false-positive result in those with dilute or concentrated urines, respectively. The dipstick test for these analytes permits the simple identification of individuals with possible albuminuria and could serve well in a point-of-care setting.
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Affiliation(s)
- M J Pugia
- Diagnostics Business Group, Bayer Corporation, Elkhart, Indiana, USA
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21
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Abstract
With the advent of much more precise laboratory equipment, the use of performance-based standard deviations for enzymes, e.g. those based on the precision of the laboratory during a period of "satisfactory performance", is not appropriate; it leads to overly rigid precision limits and unnecessary repeat assays, and is wasteful of resources. Testing for the commonly used serum enzymes does not require tight precision given how enzyme data are viewed by most clinicians. Other ways to set process control limits all have some arbitrary content; however, this need not prevent their use. Laboratorians must choose the approach that is appropriate for their laboratory and medical staff to meet medically perceived needs.
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Affiliation(s)
- J A Lott
- Department of Pathology, The Ohio State University Medical Center, Columbus 43210, USA.
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22
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Pugia MJ, Lott JA, Kajima J, Saambe T, Sasaki M, Kuromoto K, Nakamura R, Fusegawa H, Ohta Y. Screening school children for albuminuria, proteinuria and occult blood with dipsticks. Clin Chem Lab Med 1999; 37:149-57. [PMID: 10219504 DOI: 10.1515/cclm.1999.027] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Beginning in 1974, the Japanese Ministry of Health Welfare directed the screening of schoolchildren for proteinuria. We studied their procedure and methods in 6197 school children and also evaluated a new urine dipstick that measures albumin concentrations down to about 10 mg/l and creatinine down to about 300 mg/l. We used specimens from adult in- and outpatients to test the accuracy of the dipsticks. Based on the quantitative results, we set as cutoffs < 150 mg/l for protein and < 30 mg/l for albumin as the concentrations representing "low risk." The quantitative values were assumed to be correct, and the dipstick results were judged accordingly, i.e., a dipstick protein of > or = "150" mg/l or an albumin of I "30" mg/l indicated increased risk of developing or having a genitourinary disorder. The sensitivity/specificity of the protein dipstick was 95.1%/95.5%, and the same for the albumin dipstick was 83.8%/93.8%. The cut-off for the albumin dipsticks probably should be set somewhat lower to reduce the number of false negatives and increase the sensitivity of the dipstick. When we compared the quantitative albumin to the protein dipsticks with the above cut-offs, we found the sensitivity/specificity to be 79.3%/94.4%, i.e., much like the albumin dipstick results. The many reports on the association of albuminuria and risk of renal disease recommend that screening should be done for albumin rather than protein. Based on the data from the school children, we estimate that a dipstick albumin of "30" mg/l is borderline increased risk, and that a protein dipstick of "150" mg/l is the same. If we call the dipstick "10" mg/l albumin, "30" mg/l albumin and the "150" mg/l protein results "low risk," then we estimate the prevalence of albuminuria in the school children to be about 2.1% and proteinuria to be about 4.3%. Children with these values should have a quantitative test for albumin and protein. We also tested a dipstick for creatinine and found increasing values with increasing age in both genders; the older boys had significantly higher creatinine values than the older girls and younger boys. For the albumin/creatinine ratio, we found 6028 children with a ratio of < 30 mg/g indicating low risk and 159 children with a ratio of > or = 30 mg/g indicating increased risk. The ratio may be more useful owing to the likely reduction of the number of false negatives and false positives.
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Affiliation(s)
- M J Pugia
- Diagnostics Business Group, Bayer Corporation, Elkhart, USA
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23
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Lott JA, Curtis LW, Thompson A, Gechlik GA, Rund DA. Reported alcohol consumption and the serum carbohydrate-deficient transferrin test in third-year medical students. Clin Chim Acta 1998; 276:129-41. [PMID: 9764731 DOI: 10.1016/s0009-8981(98)00096-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
The serum carbohydrate-deficient transferrin (CDT) test was performed on 143 third-year medical students along with questionnaires for the self-reporting of alcohol consumption during the last 2 weeks, the last 6 months, and questions on any alcohol-related untoward events. We found that the CDT test has poor sensitivity for detecting binge drinking in our population of students, despite some likely under-reporting of drinking. Self-reporting of drinking is commonly unreliable, and we found no significant correlation between the CDT concentrations in serum and the magnitude of self-reported alcohol use during 2-week and 6-month periods. Hangover was by far the commonest self-reported untoward event, and there was a highly significant relationship (P < 0.001) between drinking and untoward events. From a small population of non-drinkers, we estimated the reference ranges for CDT to be <27 U/l for men and <35 U/l for women.
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Affiliation(s)
- J A Lott
- Department of Pathology, The Ohio State University Medical Center, Columbus 43210, USA
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24
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Cutler SJ, DeWitt Blanton C, Akin DT, Steinberg FB, Moore AB, Lott JA, Price TC, May SW, Pollock SH. Pharmacological evaluation of 1-(carboxymethyl)-3,5-diphenyl-2-methylbenzene, a novel arylacetic acid with potential anti-inflammatory properties. Inflamm Res 1998; 47:316-24. [PMID: 9719496 DOI: 10.1007/s000110050335] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
OBJECTIVE AND DESIGN 1-(Carboxymethyl)-3,5-diphenyl-2-methylbenzene (CDB), a novel arylacetic acid, was evaluated in vivo for its ability to inhibit acute and chronic inflammation as well as acute pain. MATERIALS AND METHODS The effects of CDB were evaluated using the following assays: 1) acute inflammation induced by the injection of carrageenan, bradykinin and serotonin into the subplantar region of the hind paw of rats; 2) chronic inflammation produced by the injection of Mycobacterium butyricum into the base of the tail of rats; 3) acute pain induced by the i.p. injection of phenyl-p-quinone into mice resulting in the production of writhes; 4) cyclooxygenase (COX) activity, including COX-1 and COX-2, evaluated using whole blood; and 5) activity of peptidylglycine alpha-monooxygenase (PAM) isolated from Xenopus laevis skin. RESULTS CDB (10 to 100mg/kg s.c.) produced a dose-dependent inhibition of carrageenan edema (ED50 of 41 mg/ kg at 3 h) which continued for up to 12 h. Using a therapeutic dosing regimen, this compound inhibited hind paw inflammation (>70%) and arthogram scores in rats with adjuvant-induced arthritis. This compound also possessed significant analgesic activity in mice (70% inhibition with 50mg/kg). CDB, however, lacked inhibitory activity on bradykinin and serotonin-induced edema. In addition, CDB significantly inhibited COX-I activity (IC50 approximately = 17 microM) while having only a weak inhibitory activity on both COX-2 and PAM activity. CONCLUSIONS CDB is an effective anti-inflammatory/analgesic agent whose mechanism of action appears to be associated with inhibition of COX-1 activity.
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Affiliation(s)
- S J Cutler
- Department of Pharmaceutical Sciences, Mercer University, Atlanta, GA 30341, USA
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25
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Abstract
Oxidized low-density lipoprotein (ox-LDL) plays an important role in atherogenesis. Atheroma formation is reduced significantly in Watanabe heritable hyperlipidemic (WHHL) rabbits by antioxidants such as probucol and vitamin E. The herbal mixture Maharishi Amrit Kalash-4 (MAK-4) inhibits Cu+2 -induced LDL oxidation, and enzymatic- and nonenzymatic-induced microsomal lipid peroxidation. We tested the effect of MAK-4 on the development of atheroma in WHHL rabbits. Eleven rabbits were divided into two groups: controls (n = 5) and a group fed 6% (w/w) MAK-4 (n = 6). Blood was drawn for biochemical analysis every two months and at necropsy, six months after the special diet was started. The aortas were preserved in formalin. The percentage area of aortic arch covered with visible plaque in the MAK-4 group (22.5 +/- 4.2%, mean +/- SE) was significantly reduced (p < 0.01) compared to the control group (47.6 +/- 6.8%, mean +/- SE). The MAK-4 group showed a significant decrease (p < 0.05) in lipid peroxide, and a significant increase (p < 0.05) in glutathione peroxidase and resistance of LDL to endothelial cell-induced and cupric ion-catalyzed oxidation (4.5 h and 5 h lag phase, respectively, for the MAK-4 group; 0 h lag phase for both for the controls). These findings suggest MAK-4 reduces atheroma formation through its antioxidant activity.
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Affiliation(s)
- J Y Lee
- Department of Pathology, College of Medicine, Ohio State University, Columbus 43210, USA
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26
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Pugia MJ, Lott JA, Clark LW, Parker DR, Wallace JF, Willis TW. Comparison of urine dipsticks with quantitative methods for microalbuminuria. Eur J Clin Chem Clin Biochem 1997; 35:693-700. [PMID: 9352232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We describe a new dip- and read dipstick that detects urine albumin at concentrations of 10 mg/l and above and urine creatinine at concentrations of 300 mg/l and above. The albumin assay is based on a high-affinity, dye-binding technique while the creatinine assay is based on the peroxidase-like activity of copper creatinine complexes. With these two-test dipsticks, urines from normal adults supplemented with albumin and creatinine were correctly identified to within +/- 15% of the expected value for both analytes; the between-day coefficients of variation ranged from 7.1% to 16.1%. We tested 275 patients' unmodified urines by the Bayer and Boehringer Mannheim Micral-Test albumin dipsticks and for albumin with the Beckman Array on the same specimens. We also analyzed 42 selected urines from the group of 275 for albumin by another quantitative immunochemical method and by electrophoresis plus a total protein method to estimate the albumin concentration. The quantitative immunochemical methods appear to underestimate the urine albumin concentrations; in these 42 urines measured as negative, i.e., < ca. 16-20 mg/l, by one of the quantitative method but positive by the Bayer dipstick, 33 of these were positive by the electrophoresis/total protein assay combination. The Bayer albumin dipstick correctly identified urines as having < 16 mg/l or > or = 16 mg/l at an 80% rate. At a cutoff of 20 mg/l, the rate increased to 87%. We also determined the urinary albumin/creatinine ratios on the 275 patients using the Bayer two-pad dipstick and found agreement 84% of the time with the same ratio obtained from a quantitative immunochemical method for albumin and a rate-Jaffe method for creatinine; an albumin/creatinine ratio (mg/g) of 30 was used as the discrimination point. Albumin stability studies performed on the Beckman Array patients with six fresh urines showed small but consistent decreases at -20 degrees C but not at 4 degrees C after one month of storage. The albumin in contrived urines, as estimated by electrophoreses/total protein and by the dipsticks did not change at these storage conditions. Boric acid at 1 g/l as a urine preservative had no effect on the measurement of albumin by any of the methods described here nor of the assay of creatinine. Other urinary proteins present at abnormal excretion rates did not interfere with the Bayer albumin dipstick. Abnormal concentrations of bilirubin, citrate, creatine, ascorbic acid, albumin, hemoglobin and myoglobin in urine did not interfere with the creatinine dipstick measurements. The first four of the above did not affect the Bayer dipstick results for albumin.
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Affiliation(s)
- M J Pugia
- Diagnostics Business Group, Bayer Corporation, Elkhart, IN, USA
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27
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Hanna AN, Waldman WJ, Lott JA, Koesters SC, Hughes AM, Thornton DJ. Increased alkaline phosphatase isoforms in autoimmune diseases. Clin Chem 1997; 43:1357-64. [PMID: 9267314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We found significant increases in ALP and ALP isoform band 10 in the serum of patients with early insulin-dependent diabetes, rheumatoid arthritis, and in those with multiple sclerosis during periods of disease exacerbation as compared with healthy controls. The ALP isoforms were assayed by isoelectric focusing. Our data suggest that the increase in ALP and ALP-10 closely reflects the abnormal activation of T lymphocytes that is common in autoimmune diseases, and that the source of the ALP-10 is activated T lymphocytes. ALP-10 is a sensitive but nonspecific marker of an active autoimmune process and appears to have the ability to detect abnormal T-cell activation. ALP-10 may be a useful test in the screening for autoimmune disorders.
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Affiliation(s)
- A N Hanna
- Department of Pathology, Ohio State University, Columbus 43210, USA
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Wallace BH, Lott JA, Griffiths J, Kirkpatrick RB. Isoforms of alkaline phosphatase determined by isoelectric focusing in patients with chronic liver disorders. Eur J Clin Chem Clin Biochem 1996; 34:711-20. [PMID: 8891523 DOI: 10.1515/cclm.1996.34.9.711] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Fractionation of alkaline phosphatase isoenzymes and isoforms by isoelectric focusing is a simple procedure that resolves up to 17 fractions having alkaline phosphatase activity. The fractions are stable at 4 degrees C, and undergo only slight changes during repeated freeze-thaw cycles. Pretreatment with phospholipase-C or sialidase changes the isoelectric focusing patterns of alkaline phosphatase in serum; we recommend they not be used owing to the loss of information. We found that the alkaline phosphatase fractions provide diagnostic information in addition to that given by the common liver-function tests in patients with chronic liver diseases. Primary biliary cirrhosis and primary sclerosing cholangitis showed similar biochemical changes, but they are very different from alcoholic cirrhosis based on the common liver-function tests and the alkaline phosphatase isoform patterns obtained by isoelectric focusing. Analysis of the laboratory data using neural networks has some limited use in distinguishing chronic and chronic-active hepatitis of any cause. We have confirmed the tissue assignments made by Griffiths (Prog Clin Biochem 1989; 8:63-74) for the alkaline phosphatase fractions in liver as obtained by isoelectric focusing: Fractions 1a and 1b show a strong correlation with biliary diseases, and fractions 2, 3, and 4 show consistent increases in patients with primary disorders of hepatocytes; these fractions have good sensitivity for hepatocyte injury, but their specificity is limited. Fraction 10 may be a marker of activated T-lymphocytes; it was abnormal in most of our patients suggesting that it is a sensitive but non-specific test. Analysis of alkaline phosphatase by isoelectric focusing deserves further evaluation, because it may facilitate the diagnosis of certain chronic liver disorders and could be a supplement to the biopsy.
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Affiliation(s)
- B H Wallace
- Department of Pathology, Ohio State University, Columbus, USA
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30
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Lott JA, Smith DA, Mitchell LC, Moeschberger ML. Use of medians and "average of normals" of patients' data for assessment of long-term analytical stability. Clin Chem 1996; 42:888-92. [PMID: 8665680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Using results from patients, we studied several methods for long-term (years) monitoring of the analytical stability of various chemistry tests. For each test, we obtained on a bimonthly basis histograms of > or = 200 to approximately 2000 data points and determined the median, mean, and mean of those data points in the reference range ("average of normal" or AON). Examining approximately 4 years' data, we found that the medians and AON are extremely stable for most tests, and that all observed shifts in the medians or in the AON could be explained by expected or unexpected changes in the laboratory. The means and peak values of the Erlang (gamma) distribution were less useful, owing to shifts caused by extreme outliers, especially for enzymes in serum. We assumed that the underlying patient population and testing patterns were stable. We recommend the use of medians or the AON of patients' data under defined conditions for monitoring the long-term analytical stability of certain tests involving serum or whole blood.
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Affiliation(s)
- J A Lott
- Department of Pathology, The Ohio State University, OSU Medical Center, Columbus, OH 43210, USA.
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Lott JA, Smith DA, Mitchell LC, Moeschberger ML. Use of medians and "average of normals" of patients' data for assessment of long-term analytical stability. Clin Chem 1996. [DOI: 10.1093/clinchem/42.6.888] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Using results from patients, we studied several methods for long-term (years) monitoring of the analytical stability of various chemistry tests. For each test, we obtained on a bimonthly basis histograms of > or = 200 to approximately 2000 data points and determined the median, mean, and mean of those data points in the reference range ("average of normal" or AON). Examining approximately 4 years' data, we found that the medians and AON are extremely stable for most tests, and that all observed shifts in the medians or in the AON could be explained by expected or unexpected changes in the laboratory. The means and peak values of the Erlang (gamma) distribution were less useful, owing to shifts caused by extreme outliers, especially for enzymes in serum. We assumed that the underlying patient population and testing patterns were stable. We recommend the use of medians or the AON of patients' data under defined conditions for monitoring the long-term analytical stability of certain tests involving serum or whole blood.
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Affiliation(s)
- J A Lott
- Department of Pathology, The Ohio State University, OSU Medical Center, Columbus, OH 43210, USA.
| | - D A Smith
- Department of Pathology, The Ohio State University, OSU Medical Center, Columbus, OH 43210, USA.
| | - L C Mitchell
- Department of Pathology, The Ohio State University, OSU Medical Center, Columbus, OH 43210, USA.
| | - M L Moeschberger
- Department of Pathology, The Ohio State University, OSU Medical Center, Columbus, OH 43210, USA.
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Guthrie RM, Lott JA, Cattaneo S, Guthrie B, Witmer V. Proteinuria as a marker for organ damage. J Fam Pract 1996; 42:85. [PMID: 8537812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Lott JA, Heinz JW, Reger KA. Time changes of creatine kinase and creatine kinase-MB isoenzyme versus discrimination values in the diagnosis of acute myocardial infarction: what is the optimal method for displaying the data? Eur J Clin Chem Clin Biochem 1995; 33:491-6. [PMID: 8547432 DOI: 10.1515/cclm.1995.33.8.491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We wanted to determine the optimal method for displaying data for the clinical evaluation of patients with possible acute myocardial infarction. Our primary question was, are the time changes (slopes) of the enzyme tests better predictors of disease than the discrimination values, i.e., the cut-off points? We studied 152 patients with and 114 without a diagnosis of acute myocardial infarction in their medical records. For patients with acute myocardial infarction, we found the most discriminating tests, in decreasing order of the area of the ROC curves, to be the creatine kinase-MB slope at 0 to 12 hours, the creatine kinase-MB slope at 12 to 24 hours, the creatine kinase-MB values between 12 and 24 hours, and the creatine kinase-MB values between 0 and 12 hours. Decreasing values of creatine kinase-MB in the first tests after admission were only slightly less discriminating than increasing ones. At 12 to 24 hours after admission, the total creatine kinase as a value or slope, or the "relative index" (a ratio of the creatine kinase-MB in microgram/l [times 100] to the total creatine kinase) as a value or slope were inferior to creatine kinase-MB presentations. From the data for 44 patients with acute myocardial infarction and a known time of onset of symptoms, we were able to estimate an approximate onset time in patients where this was not available.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J A Lott
- Department of Pathology, Ohio State University Medical Center, Columbus, USA
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Affiliation(s)
- J A Lott
- Department of Pathology, The Ohio State University, Columbus, 43210, USA
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35
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Abstract
We evaluated the Miles Inc., Clinitek Atlas Automated Urine Chemistry Analyzer for 11 tests: bilirubin, color, glucose, ketones, leukocyte esterase, nitrite, occult blood, pH, protein, specific gravity, and urobilinogen. The instrument uses a roll of reagent strips affixed to a clear plastic support; urine specimens are automatically pipetted onto these strips. The instrument measures the pads' color using reflectance colorimetry. Specific gravity is measured using a fiberoptic refractive index method. Four hospitals participated in the evaluation, and tests were performed only on fresh urine samples. We found the instrument easy to use; it has walk-away capability with up to 40-specimen loading capacity plus spaces for STATs, calibrators and controls. We found good comparability with chemical tests and other nonreagent strip procedures, as well as good agreement with the Miles Inc. Clinitek 200+ urine chemistry analyzer and visual reading of the Miles Inc. Multistix Reagent Strips. The Clinitek Atlas is rugged and reliable, and is suitable for a high-volume urinalysis laboratory.
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Affiliation(s)
- J A Lott
- Department of Pathology, Ohio State University, Columbus 43210-1240, USA
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36
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Choquette KD, Schneider RP, Lott JA. Lasing characteristics of visible AlGaInP/AlGaAs vertical-cavity lasers. Opt Lett 1994; 19:969-971. [PMID: 19844504 DOI: 10.1364/ol.19.000969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report the lasing characteristics of gain-guided AlGaInP/AlGaAs visible vertical-cavity surface-emitting laser diodes. At room temperature, continuous-wave operation is achieved over the wavelength range of 657-685 nm with the minimum threshold current at 670 nm. Devices with a 10-microm diameter have threshold currents as low as 1.25 mA at room temperature (297 K) and 0.8 mA at 250 K. In addition, a single predetermined linear polarization state is found, independent of the lasing mode order and operating temperature.
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Abstract
Abstract
Orthotopic liver transplantation (OLT) is now the only available treatment for end-stage liver disease; the major postoperative complications of OLT are rejection and infection. Fractionation of alkaline phosphatase (ALP) isoforms in serum by isoelectric focusing can be used to identify patients with complications. Reference ranges for liver-function tests (LFT) and liver ALP isoforms were established for post-OLT patients with stable postoperative courses and compared with those of patients with complications. We found canalicular, hepatocyte, and high-molecular-mass ALP to be statistically higher in nearly all patients with complications as compared with patients who had a stable postoperative course; these tests may identify patients requiring a liver biopsy. When used in conjunction with LFT and other clinical findings, ALP isoforms could aid in the monitoring of complications and treatment and in the adjustment of immunosuppressive therapy in stable OLT cases.
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Affiliation(s)
| | - J A Lott
- Department of Pathology, Ohio State University, Columbus 43210
| | - R J Tesi
- Department of Pathology, Ohio State University, Columbus 43210
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38
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Randolph-Habecker J, Lott JA, Tesi RJ. Alkaline phosphatase isoforms in serum after liver allograft surgery. Clin Chem 1994; 40:1272-7. [PMID: 8013098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Orthotopic liver transplantation (OLT) is now the only available treatment for end-stage liver disease; the major postoperative complications of OLT are rejection and infection. Fractionation of alkaline phosphatase (ALP) isoforms in serum by isoelectric focusing can be used to identify patients with complications. Reference ranges for liver-function tests (LFT) and liver ALP isoforms were established for post-OLT patients with stable postoperative courses and compared with those of patients with complications. We found canalicular, hepatocyte, and high-molecular-mass ALP to be statistically higher in nearly all patients with complications as compared with patients who had a stable postoperative course; these tests may identify patients requiring a liver biopsy. When used in conjunction with LFT and other clinical findings, ALP isoforms could aid in the monitoring of complications and treatment and in the adjustment of immunosuppressive therapy in stable OLT cases.
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Lee JY, Lott JA, Sharma HM. Biochemical changes induced by Maharishi Amrit Kalash (MAK-4) and MA-208 in diet-induced hypercholesterolemic rabbits. Adv Exp Med Biol 1994; 366:446-7. [PMID: 7771288 DOI: 10.1007/978-1-4615-1833-4_48] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- J Y Lee
- Department of Pathology, College of Medicine, Ohio State University, Columbus 43210, USA
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Lott JA, Nealon DA. Automated enzyme assays. Methods Biochem Anal 1994; 37:143-189. [PMID: 8309366 DOI: 10.1002/9780470110584.ch4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- J A Lott
- Ohio State University, Columbus 43210-1240
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Guthrie RM, Lott JA. Screening for proteinuria in patients with hypertension or diabetes mellitus. J Fam Pract 1993; 37:253-256. [PMID: 8409876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
BACKGROUND Proteinuria is an early indication of renal disease. This study was conducted to evaluate the usefulness of dipstick urinalysis in patients with chronic diseases including hypertension and diabetes mellitus. METHODS At a university family practice center, patients without urinary tract disorders underwent dipstick urinalysis. RESULTS Of the 796 patients evaluated, increased proteinuria, possibly indicating early renal disease, was detected in 4% of healthy patients, 16% of patients with hypertension, 29% of patients with diabetes, and 53% of patients with both hypertension and diabetes. A higher incidence of proteinuria was found among African American patients with hypertension or diabetes or both than among white patients. CONCLUSIONS Regular dipstick evaluation for proteinuria may be indicated in patients with hypertension or diabetes mellitus or both, particularly African American patients with these disorders.
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Affiliation(s)
- R M Guthrie
- Department of Emergency Medicine, Ohio State University, Columbus 43210
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Lott JA, Doumas BT. "Direct" and total bilirubin tests: contemporary problems. Clin Chem 1993; 39:641-7. [PMID: 8472359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In eight unique challenges mailed by The College of American Pathologists Comprehensive Chemistry Survey to participating laboratories within 3 years, results for direct-reacting bilirubin (DBIL) were highly variable among the 12 largest peer groups, and most of the results differed greatly from the values obtained by a referred method. Peer-group mean values for total bilirubin (TBIL) were in much better agreement with each other and with those obtained by the Reference Method for TBIL. From a review of the information on the assay of DBIL provided to us by the manufacturers, we conclude that among the major causes of the large variability and bias in DBIL assays are problems with calibration, lack of a serum blank measurement, inadequate concentrations of HCl in the reaction mixture, inappropriate use of bichromatic correction methods, and possibly the use of wetting agents or surfactants in the reagent. Within-group SDs were small and generally acceptable. The among-peer-group variability in DBIL values is attributable to bias, not imprecision. We recommend several simple changes that could improve the accuracy of DBIL determinations in clinical laboratories.
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Affiliation(s)
- J A Lott
- Department of Pathology, Ohio State University, Columbus 43210-1240
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Lott JA, Bowers GN. College of American Pathologists Conference XXIII on matrix effects and accuracy assessment in clinical chemistry. Report of Working Group on Accuracy Transfer. Arch Pathol Lab Med 1993; 117:433-5. [PMID: 8466412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- J A Lott
- Department of Pathology, Ohio State University Medical Center, Columbus 43210-1240
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Abstract
Abstract
In eight unique challenges mailed by The College of American Pathologists Comprehensive Chemistry Survey to participating laboratories within 3 years, results for direct-reacting bilirubin (DBIL) were highly variable among the 12 largest peer groups, and most of the results differed greatly from the values obtained by a referred method. Peer-group mean values for total bilirubin (TBIL) were in much better agreement with each other and with those obtained by the Reference Method for TBIL. From a review of the information on the assay of DBIL provided to us by the manufacturers, we conclude that among the major causes of the large variability and bias in DBIL assays are problems with calibration, lack of a serum blank measurement, inadequate concentrations of HCl in the reaction mixture, inappropriate use of bichromatic correction methods, and possibly the use of wetting agents or surfactants in the reagent. Within-group SDs were small and generally acceptable. The among-peer-group variability in DBIL values is attributable to bias, not imprecision. We recommend several simple changes that could improve the accuracy of DBIL determinations in clinical laboratories.
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Affiliation(s)
- J A Lott
- Department of Pathology, Ohio State University, Columbus 43210-1240
| | - B T Doumas
- Department of Pathology, Ohio State University, Columbus 43210-1240
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Abstract
Abstract
We measured Na, K, Cl, glucose, hemoglobin, erythrocytes, and hematocrit in the serum or blood from approximately 800 male and 200 female second-year medical students in an effort to define the size of an acceptable reference population. Using the data from the men and Monte Carlo simulations of 10-400 samples, each carried out 5000 times, we found that for most of the above tests, approximately 200 people are required for stable lower (2.5%) and upper (97.5%) reference limits to be obtained. This agrees with the 198 subjects required by strictly statistical criteria to define the same limits with a 99% confidence level.
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Affiliation(s)
- J A Lott
- Department of Pathology, Ohio State University, Columbus 43210
| | - L C Mitchell
- Department of Pathology, Ohio State University, Columbus 43210
| | | | - D E Sutherland
- Department of Pathology, Ohio State University, Columbus 43210
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Lott JA, Mitchell LC, Moeschberger ML, Sutherland DE. Estimation of reference ranges: how many subjects are needed? Clin Chem 1992; 38:648-50. [PMID: 1582014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We measured Na, K, Cl, glucose, hemoglobin, erythrocytes, and hematocrit in the serum or blood from approximately 800 male and 200 female second-year medical students in an effort to define the size of an acceptable reference population. Using the data from the men and Monte Carlo simulations of 10-400 samples, each carried out 5000 times, we found that for most of the above tests, approximately 200 people are required for stable lower (2.5%) and upper (97.5%) reference limits to be obtained. This agrees with the 198 subjects required by strictly statistical criteria to define the same limits with a 99% confidence level.
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Affiliation(s)
- J A Lott
- Department of Pathology, Ohio State University, Columbus 43210
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Kazmierczak SC, Lott JA. Monitoring of intestinal transplant rejection. Am J Surg 1991; 162:90. [PMID: 1905881 DOI: 10.1016/0002-9610(91)90211-u] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Anderson DJ, Van Lente F, Apple FS, Kazmierczak SC, Lott JA, Gupta MK, McBride N, Katzin WE, Scott RE, Toffaletti J. Clinical chemistry. Anal Chem 1991; 63:165R-270R. [PMID: 1872480 DOI: 10.1021/ac00012a011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- D J Anderson
- Department of Chemistry, Cleveland State University, Ohio 44115
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Lott JA. Strengthening the weak links in lab services. MLO Med Lab Obs 1991; 23:30-4. [PMID: 10111654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Lott JA. The value of clinical laboratory studies in acute pancreatitis. Arch Pathol Lab Med 1991; 115:325-6. [PMID: 1707260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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