Christoph Ebert - Academia.edu (original) (raw)

Papers by Christoph Ebert

Research paper thumbnail of Improved troponin T ELISA specific for cardiac troponin T isoform: Assay development and analytical and clinical validation

Clinical Chemistry

The first generation of troponin T ELISA (TnT 1) can yield false-positive results in patients wit... more The first generation of troponin T ELISA (TnT 1) can yield false-positive results in patients with severe skeletal muscle injury. Therefore, a cardiac-specific secondgeneration troponin T ELISA (TnT 2) was developed, in which the cross-reactive antibody 1B10 has been replaced by a high-affinity cardiac-specific antibody M11.7. No cross-reactivity of TnT 2 was observed with purified skeletal muscle troponin T (1000 g/L) or in test samples from 43 marathon runners and 24 patients with rhabdomyolysis and highly increased creatine kinase. TnT 2 was increased >0.2 g/L in 5 of 40 patients with renal failure and in 4 of 20 muscular dystrophy patients. The detection limit is 0.012 g/L. Day-to-day imprecision (CV) within the range 0.19 -14.89 g/L was <5.8%. In 4955 patients without myocardial damage, 99.6% had TnT <0.10 g/L. Assay comparison (TnT 1 vs TnT 2) over the whole concentration range (i.e., in 323 samples from AMI-suspected patients) showed a slope, intercept, and standard error of estimate (Sey) of 1.18, 0.01 g/L, and 0.81 g/L, respectively. 5 Nonstandard abbreviations: TnT 1, first version of the troponin T ELISA; TnT 2, newly developed assay with two cardiac-specific antibodies; AMI, acute myocardial infarction; cTnT, cardiac troponin T; CK, creatine kinase; Sey, standard error of the estimate (S y͉x ); SDS-PAGE, sodium dodecyl sulfatepolyacrylamide gel electrophoresis; BSA, bovine serum albumin; and PBS, phosphate-buffered saline.

Research paper thumbnail of Elecsys TSH, FT4, T4, T-uptake, FT3 and T3. Clinical results of a multicentre study

Wiener klinische Wochenschrift

6 assays for the assessment of thyroid function (TSH, FT4, T4, T-uptake, FT3 and T3) were targets... more 6 assays for the assessment of thyroid function (TSH, FT4, T4, T-uptake, FT3 and T3) were targets of the International Multicenter Study on the random access analyzer Elecsys 2010. The aim of the study was to characterize the clinical performance of the assay in method comparison and reference range studies. The assays under evaluation were compared to a broad variety of radio isotopic and non-radio isotopic assays. They are suitable for serum and plasma samples. In case of TSH the study include 2nd and 3rd generation TSH procedures. In general, good to excellent correlations were found between the Elecsys and the respective routine methods. Systematic deviations were extraordinary low in case of TSH, FT4 and T4. Regarding the analysis of T3 and FT3 some systematic deviations in terms of standardization have been observed. Results of Elecsys T4 and Elecsys FT4 were independent of the serum total protein or serum albumin concentrations. In T3 and FT3 Elecsys the results of samples fr...

Research paper thumbnail of Glycosylated Inactive Forms of Chicken Butyrylcholinesterases and Their Possible Functions

Enzymes of the Cholinesterase Family, 1995

Research paper thumbnail of Multicenter evaluation of a second-generation assay for cardiac troponin T

Clinical chemistry, 1997

We report on the evaluation of the second-generation assay for cardiac troponin T (cTnT) on the E... more We report on the evaluation of the second-generation assay for cardiac troponin T (cTnT) on the Enzymun system. This new assay is completely specific for the cardiac isoform of TnT, utilizing two cardiospecific monoclonal antibodies. The assay time is reduced to 45 min. The interassay precision shows a median CV of 5.5%; 20% interassay CV was found between 0.05 and 0.1 microg/L. The cardiosensitivity of the second-generation cTnT assay in patients with ischemic myocardial injury appears equivalent when compared with the first-generation assay. We found no falsely positive results in patients with skeletal muscle damage including multitraumas, surgery patients, and marathon runners who showed highly increased values with the unspecific first-generation assay. In Duchenne disease cTnT was still increased, but to a much lower extent. cTnT remains increased in renal failure, but to a lesser degree than with the first-generation assay. The cause of this increase remains unclear. Although...

Research paper thumbnail of Improved troponin T ELISA specific for cardiac troponin T isoform: assay development and analytical and clinical validation

Clinical chemistry, 1997

The first generation of troponin T ELISA (TnT 1) can yield false-positive results in patients wit... more The first generation of troponin T ELISA (TnT 1) can yield false-positive results in patients with severe skeletal muscle injury. Therefore, a cardiac-specific second-generation troponin T ELISA (TnT 2) was developed, in which the cross-reactive antibody 1B10 has been replaced by a high-affinity cardiac-specific antibody M11.7. No cross-reactivity of TnT 2 was observed with purified skeletal muscle troponin T (1000 micrograms/L) or in test samples from 43 marathon runners and 24 patients with rhabdomyolysis and highly increased creatine kinase. TnT 2 was increased > 0.2 microgram/L in 5 of 40 patients with renal failure and in 4 of 20 muscular dystrophy patients. The detection limit is 0.012 microgram/L. Day-to-day imprecision (CV) within the range 0.19-14.89 micrograms/L was < 5.8%. In 4955 patients without myocardial damage, 99.6% had TnT < 0.10 microgram/L. Assay comparison (TnT 1 vs TnT 2) over the whole concentration range (i.e., in 323 samples from AMI-suspected patie...

Research paper thumbnail of Current Evidence and Future Perspectives on the Effective Practice of Patient-Centered Laboratory Medicine

Clinical Chemistry, 2015

Systematic evidence of the contribution made by laboratory medicine to patient outcomes and the o... more Systematic evidence of the contribution made by laboratory medicine to patient outcomes and the overall process of healthcare is difficult to find. An understanding of the value of laboratory medicine, how it can be determined, and the various factors that influence it is vital to ensuring that the service is provided and used optimally. This review summarizes existing evidence supporting the impact of laboratory medicine in healthcare and indicates the gaps in our understanding. It also identifies deficiencies in current utilization, suggests potential solutions, and offers a vision of a future in which laboratory medicine is used optimally to support patient care. To maximize the value of laboratory medicine, work is required in 5 areas: (a) improved utilization of existing and new tests; (b) definition of new roles for laboratory professionals that are focused on optimizing patient outcomes by adding value at all points of the diagnostic brain-to-brain cycle; (c) development of standardized protocols for prospective patient-centered studies of biomarker clinical effectiveness or extraanalytical process effectiveness; (d) benchmarking of existing and new tests in specified situations with commonly accepted measures of effectiveness; (e) agreed definition and validation of effectiveness measures and use of checklists for articles submitted for publication. Progress in these areas is essential if we are to demonstrate and enhance the value of laboratory medicine and prevent valuable information being lost in meaningless data. This requires effective collaboration with clinicians, and a determination to accept patient outcome and patient experience as the primary measure of laboratory effectiveness.

Research paper thumbnail of Homology between 4.3 ?m minicircular and plastomic DNA in chloroplasts of Acetabularia cliftonii

MGG Molecular & General Genetics, 1985

In addition to high molecular weight plastomic DNA, chloroplasts of Acetabularia cliftonii also c... more In addition to high molecular weight plastomic DNA, chloroplasts of Acetabularia cliftonii also contain small supercoiled DNA molecules (Green 1976). Restriction enzyme analysis of this 4.28±0.15 µm DNA resulted in a 14.1 kbp circular restriction map. Southern blot analysis revealed that the high molecular weight plastomic DNA of A. cliftonii contains all of the 4.3 µm DNA restriction fragments suggesting

Research paper thumbnail of Butyrylcholinesterase from Chicken Brain Is Smaller than That from Serum: Its Purification, Glycosylation, and Membrane Association

Journal of Neurochemistry, 1992

Applying a new four-step isolation procedure, we have purified butyrylcholinesterase (BChE) from ... more Applying a new four-step isolation procedure, we have purified butyrylcholinesterase (BChE) from chicken serum to homogeneity with more than 250 U/mg specific activity. The serum enzyme was used for producing monoclonal antibodies. These BChE-specific antibodies also recognize BChE from brain, and thus enabled us to isolate the enzymes from embryonic and adult brain that occur only in minute amounts. More than 50% of the brain BChE is membrane-bound. The catalytic and inhibition properties of brain BChE are similar to those of serum BChE. However on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the serum enzyme is represented by a double-band of 79/82 kDa, whereas the brain enzyme has a size of 74 kDa. Limited digestion of the serum and brain preparations by VR-protease leads to similar peptide patterns. En-zymatic deglycosylation shows that their core proteins consist of 59-kDa subunits and that the different molecular weights are due to different glycosylation patterns. The differently sized glycosylation parts of brain and serum BChE may indicate that they subserve different functions. Furthermore, the membrane-bound brain BChE can be solubilized by Pronase or protease K, but not by phosphatidylinositolspecific phospholipase C. Key Words: Cholinergic system-Serine hydrolases-Glycosylation-Phosphatidylinositolspecific phospholipase C-Acetylcholinesterase. Treskatis S. et al. Butyrylcholinesterase from chicken brain is smaller than that from serum: Its purification, glycosylation, and membrane association.

Research paper thumbnail of Novel Inactive and Distinctively Glycosylated Forms of Butyrylcholinesterase from Chicken Serum

Journal of Neurochemistry, 2002

Three different homologues of butyrylcholinesterase (BChE) with 75-, 62-, and 54-kDa subunit size... more Three different homologues of butyrylcholinesterase (BChE) with 75-, 62-, and 54-kDa subunit size are isolated from adult chicken serum, and all show very low or zero enzyme activity. Although the active BChE from serum with a subunit size of 81 kDa forms tetramers, the 75-kDa protein is isolated as a dimer. The homology of the 75-kDa protein with active BChE is shown by immunoreactivity with BChE-specific monoclonal antibodies, by coisolation with the active BChE, and by their identical first six N-terminal amino acids. By deglycosylation of these proteins and by their differential lectin binding, we show that the active BChE is an N-glycosylated protein of the triantennary type, whereas the inactive 75-kDa protein is O-glycosylated. These data show for the first time the existence of (1) multiple inactive forms of BChE, (2) secreted inactive cholinesterases, because they are found in serum, and (3) an O-glycosylated cholinesterase. Because cholinesterases can regulate neurite growth in vitro by a nonenzymatic mechanism, these data strongly support that both inactive and active forms of BChE may be involved in noncholinergic communication, possibly depending on particular glycosylation patterns.

Research paper thumbnail of Multicentre performance evaluation of the E170 Module for MODULAR ANALYTICS

Clinical Chemistry and Laboratory Medicine, 2000

The E170 module was evaluated at 13 sites in an international multicentre study. The objective of... more The E170 module was evaluated at 13 sites in an international multicentre study. The objective of the study was to assess the analytical performance of 49 analytes, and to collect feedback on the system&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s reliability and practicability. The typical, within-run coefficients of variation (CVs) for most of the quantitative assays ranged between 1 and 2% while a range of 2-4% was achieved with the infectious disease methods. Total precision CVs were found to be within the manufacturer&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s expected performance ranges, demonstrating good concordance of the system&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s measuring channels and a high reproducibility during the 2-4-week trial period. The functional sensitivity of 11 selected assays met the clinical requirements (e.g., thyreotroponin (TSH) 0.008 mU/l, troponin T 0.02 microg/l, total prostate-specific antigen (PSA) 0.03 microg/l). The E170 showed no drift during an 8-hour period and no relevant reagent carryover. Accuracy was confirmed by ring trial experiments and method comparisons vs. Elecsys 2010. The reliability and practicability of the system&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s hardware and software met with, or even exceeded, the evaluator&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s requirements. Workflow studies showed that E170 can cover the combined workload of various routine analysers in a variety of laboratory environment. Throughput and sample processing time requirements were achieved while personnel &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;hands-on-time&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; could be reduced.

Research paper thumbnail of From biomarkers to medical tests: The changing landscape of test evaluation

Clinica Chimica Acta, 2014

Regulators and healthcare payers are increasingly demanding evidence that biomarkers deliver pati... more Regulators and healthcare payers are increasingly demanding evidence that biomarkers deliver patient benefits to justify their use in clinical practice. Laboratory professionals need to be familiar with these evidence requirements to better engage in biomarker research and decisions about their appropriate use. This paper by a multidisciplinary group of the European Federation of Clinical Chemistry and Laboratory Medicine describes the pathway of a laboratory assay measuring a biomarker to becoming a medically useful test. We define the key terms, principles and components of the test evaluation process. Unlike previously described linearly staged models, we illustrate how the essential components of analytical and clinical performances, clinical and cost-effectiveness and the broader impact of testing assemble in a dynamic cycle. We highlight the importance of defining clinical goals and how the intended application of the biomarker in the clinical pathway should drive each component of test evaluation. This approach emphasizes the interaction of the different components, and that clinical effectiveness data should be fed back to refine analytical and clinical performances to achieve improved outcomes. The framework aims to support the understanding of key stakeholders. The laboratory profession needs to strengthen collaboration with industry and experts in evidence-based medicine, regulatory bodies and policy makers for better decisions about the use of new and existing medical tests.

Research paper thumbnail of Setting analytical performance specifications based on outcome studies – is it possible?

Clinical Chemistry and Laboratory Medicine (CCLM), 2015

The 1st Strategic Conference of the European Federation of Clinical Chemistry and Laboratory Medi... more The 1st Strategic Conference of the European Federation of Clinical Chemistry and Laboratory Medicine proposed a simplified hierarchy for setting analytical performance specifications (APS). The top two levels of the 1999 Stockholm hierarchy, i.e., evaluation of the effect of analytical performance on clinical outcomes and clinical decisions have been proposed to be replaced by one outcome-based model. This model can be supported by: (1a) direct outcome studies; and (1b) indirect outcome studies investigating the impact of analytical performance of the test on clinical classifications or decisions and thereby on the probability of patient relevant clinical outcomes. This paper reviews the need for outcome-based specifications, the most relevant types of outcomes to be considered, and the challenges and limitations faced when setting outcome-based APS. The methods of Model 1a and b are discussed and examples are provided for how outcome data can be translated to APS using the linked evidence and simulation or decision analytic techniques. Outcome-based APS should primarily reflect the clinical needs of patients; should be tailored to the purpose, role and significance of the test in a well defined clinical pathway; and should be defined at a level that achieves net health benefit for patients at reasonable costs. Whilst it is acknowledged that direct evaluations are difficult and may not be possible for all measurands, all other forms of setting APS should be weighed against that standard, and regarded as approximations. Better definition of the relationship between the analytical performance of tests and health outcomes can be used to set analytical performance criteria that aim to improve the clinical and cost-effectiveness of laboratory tests.

Research paper thumbnail of Improved troponin T ELISA specific for cardiac troponin T isoform: Assay development and analytical and clinical validation

Clinical Chemistry

The first generation of troponin T ELISA (TnT 1) can yield false-positive results in patients wit... more The first generation of troponin T ELISA (TnT 1) can yield false-positive results in patients with severe skeletal muscle injury. Therefore, a cardiac-specific secondgeneration troponin T ELISA (TnT 2) was developed, in which the cross-reactive antibody 1B10 has been replaced by a high-affinity cardiac-specific antibody M11.7. No cross-reactivity of TnT 2 was observed with purified skeletal muscle troponin T (1000 g/L) or in test samples from 43 marathon runners and 24 patients with rhabdomyolysis and highly increased creatine kinase. TnT 2 was increased >0.2 g/L in 5 of 40 patients with renal failure and in 4 of 20 muscular dystrophy patients. The detection limit is 0.012 g/L. Day-to-day imprecision (CV) within the range 0.19 -14.89 g/L was <5.8%. In 4955 patients without myocardial damage, 99.6% had TnT <0.10 g/L. Assay comparison (TnT 1 vs TnT 2) over the whole concentration range (i.e., in 323 samples from AMI-suspected patients) showed a slope, intercept, and standard error of estimate (Sey) of 1.18, 0.01 g/L, and 0.81 g/L, respectively. 5 Nonstandard abbreviations: TnT 1, first version of the troponin T ELISA; TnT 2, newly developed assay with two cardiac-specific antibodies; AMI, acute myocardial infarction; cTnT, cardiac troponin T; CK, creatine kinase; Sey, standard error of the estimate (S y͉x ); SDS-PAGE, sodium dodecyl sulfatepolyacrylamide gel electrophoresis; BSA, bovine serum albumin; and PBS, phosphate-buffered saline.

Research paper thumbnail of Elecsys TSH, FT4, T4, T-uptake, FT3 and T3. Clinical results of a multicentre study

Wiener klinische Wochenschrift

6 assays for the assessment of thyroid function (TSH, FT4, T4, T-uptake, FT3 and T3) were targets... more 6 assays for the assessment of thyroid function (TSH, FT4, T4, T-uptake, FT3 and T3) were targets of the International Multicenter Study on the random access analyzer Elecsys 2010. The aim of the study was to characterize the clinical performance of the assay in method comparison and reference range studies. The assays under evaluation were compared to a broad variety of radio isotopic and non-radio isotopic assays. They are suitable for serum and plasma samples. In case of TSH the study include 2nd and 3rd generation TSH procedures. In general, good to excellent correlations were found between the Elecsys and the respective routine methods. Systematic deviations were extraordinary low in case of TSH, FT4 and T4. Regarding the analysis of T3 and FT3 some systematic deviations in terms of standardization have been observed. Results of Elecsys T4 and Elecsys FT4 were independent of the serum total protein or serum albumin concentrations. In T3 and FT3 Elecsys the results of samples fr...

Research paper thumbnail of Glycosylated Inactive Forms of Chicken Butyrylcholinesterases and Their Possible Functions

Enzymes of the Cholinesterase Family, 1995

Research paper thumbnail of Multicenter evaluation of a second-generation assay for cardiac troponin T

Clinical chemistry, 1997

We report on the evaluation of the second-generation assay for cardiac troponin T (cTnT) on the E... more We report on the evaluation of the second-generation assay for cardiac troponin T (cTnT) on the Enzymun system. This new assay is completely specific for the cardiac isoform of TnT, utilizing two cardiospecific monoclonal antibodies. The assay time is reduced to 45 min. The interassay precision shows a median CV of 5.5%; 20% interassay CV was found between 0.05 and 0.1 microg/L. The cardiosensitivity of the second-generation cTnT assay in patients with ischemic myocardial injury appears equivalent when compared with the first-generation assay. We found no falsely positive results in patients with skeletal muscle damage including multitraumas, surgery patients, and marathon runners who showed highly increased values with the unspecific first-generation assay. In Duchenne disease cTnT was still increased, but to a much lower extent. cTnT remains increased in renal failure, but to a lesser degree than with the first-generation assay. The cause of this increase remains unclear. Although...

Research paper thumbnail of Improved troponin T ELISA specific for cardiac troponin T isoform: assay development and analytical and clinical validation

Clinical chemistry, 1997

The first generation of troponin T ELISA (TnT 1) can yield false-positive results in patients wit... more The first generation of troponin T ELISA (TnT 1) can yield false-positive results in patients with severe skeletal muscle injury. Therefore, a cardiac-specific second-generation troponin T ELISA (TnT 2) was developed, in which the cross-reactive antibody 1B10 has been replaced by a high-affinity cardiac-specific antibody M11.7. No cross-reactivity of TnT 2 was observed with purified skeletal muscle troponin T (1000 micrograms/L) or in test samples from 43 marathon runners and 24 patients with rhabdomyolysis and highly increased creatine kinase. TnT 2 was increased > 0.2 microgram/L in 5 of 40 patients with renal failure and in 4 of 20 muscular dystrophy patients. The detection limit is 0.012 microgram/L. Day-to-day imprecision (CV) within the range 0.19-14.89 micrograms/L was < 5.8%. In 4955 patients without myocardial damage, 99.6% had TnT < 0.10 microgram/L. Assay comparison (TnT 1 vs TnT 2) over the whole concentration range (i.e., in 323 samples from AMI-suspected patie...

Research paper thumbnail of Current Evidence and Future Perspectives on the Effective Practice of Patient-Centered Laboratory Medicine

Clinical Chemistry, 2015

Systematic evidence of the contribution made by laboratory medicine to patient outcomes and the o... more Systematic evidence of the contribution made by laboratory medicine to patient outcomes and the overall process of healthcare is difficult to find. An understanding of the value of laboratory medicine, how it can be determined, and the various factors that influence it is vital to ensuring that the service is provided and used optimally. This review summarizes existing evidence supporting the impact of laboratory medicine in healthcare and indicates the gaps in our understanding. It also identifies deficiencies in current utilization, suggests potential solutions, and offers a vision of a future in which laboratory medicine is used optimally to support patient care. To maximize the value of laboratory medicine, work is required in 5 areas: (a) improved utilization of existing and new tests; (b) definition of new roles for laboratory professionals that are focused on optimizing patient outcomes by adding value at all points of the diagnostic brain-to-brain cycle; (c) development of standardized protocols for prospective patient-centered studies of biomarker clinical effectiveness or extraanalytical process effectiveness; (d) benchmarking of existing and new tests in specified situations with commonly accepted measures of effectiveness; (e) agreed definition and validation of effectiveness measures and use of checklists for articles submitted for publication. Progress in these areas is essential if we are to demonstrate and enhance the value of laboratory medicine and prevent valuable information being lost in meaningless data. This requires effective collaboration with clinicians, and a determination to accept patient outcome and patient experience as the primary measure of laboratory effectiveness.

Research paper thumbnail of Homology between 4.3 ?m minicircular and plastomic DNA in chloroplasts of Acetabularia cliftonii

MGG Molecular & General Genetics, 1985

In addition to high molecular weight plastomic DNA, chloroplasts of Acetabularia cliftonii also c... more In addition to high molecular weight plastomic DNA, chloroplasts of Acetabularia cliftonii also contain small supercoiled DNA molecules (Green 1976). Restriction enzyme analysis of this 4.28±0.15 µm DNA resulted in a 14.1 kbp circular restriction map. Southern blot analysis revealed that the high molecular weight plastomic DNA of A. cliftonii contains all of the 4.3 µm DNA restriction fragments suggesting

Research paper thumbnail of Butyrylcholinesterase from Chicken Brain Is Smaller than That from Serum: Its Purification, Glycosylation, and Membrane Association

Journal of Neurochemistry, 1992

Applying a new four-step isolation procedure, we have purified butyrylcholinesterase (BChE) from ... more Applying a new four-step isolation procedure, we have purified butyrylcholinesterase (BChE) from chicken serum to homogeneity with more than 250 U/mg specific activity. The serum enzyme was used for producing monoclonal antibodies. These BChE-specific antibodies also recognize BChE from brain, and thus enabled us to isolate the enzymes from embryonic and adult brain that occur only in minute amounts. More than 50% of the brain BChE is membrane-bound. The catalytic and inhibition properties of brain BChE are similar to those of serum BChE. However on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the serum enzyme is represented by a double-band of 79/82 kDa, whereas the brain enzyme has a size of 74 kDa. Limited digestion of the serum and brain preparations by VR-protease leads to similar peptide patterns. En-zymatic deglycosylation shows that their core proteins consist of 59-kDa subunits and that the different molecular weights are due to different glycosylation patterns. The differently sized glycosylation parts of brain and serum BChE may indicate that they subserve different functions. Furthermore, the membrane-bound brain BChE can be solubilized by Pronase or protease K, but not by phosphatidylinositolspecific phospholipase C. Key Words: Cholinergic system-Serine hydrolases-Glycosylation-Phosphatidylinositolspecific phospholipase C-Acetylcholinesterase. Treskatis S. et al. Butyrylcholinesterase from chicken brain is smaller than that from serum: Its purification, glycosylation, and membrane association.

Research paper thumbnail of Novel Inactive and Distinctively Glycosylated Forms of Butyrylcholinesterase from Chicken Serum

Journal of Neurochemistry, 2002

Three different homologues of butyrylcholinesterase (BChE) with 75-, 62-, and 54-kDa subunit size... more Three different homologues of butyrylcholinesterase (BChE) with 75-, 62-, and 54-kDa subunit size are isolated from adult chicken serum, and all show very low or zero enzyme activity. Although the active BChE from serum with a subunit size of 81 kDa forms tetramers, the 75-kDa protein is isolated as a dimer. The homology of the 75-kDa protein with active BChE is shown by immunoreactivity with BChE-specific monoclonal antibodies, by coisolation with the active BChE, and by their identical first six N-terminal amino acids. By deglycosylation of these proteins and by their differential lectin binding, we show that the active BChE is an N-glycosylated protein of the triantennary type, whereas the inactive 75-kDa protein is O-glycosylated. These data show for the first time the existence of (1) multiple inactive forms of BChE, (2) secreted inactive cholinesterases, because they are found in serum, and (3) an O-glycosylated cholinesterase. Because cholinesterases can regulate neurite growth in vitro by a nonenzymatic mechanism, these data strongly support that both inactive and active forms of BChE may be involved in noncholinergic communication, possibly depending on particular glycosylation patterns.

Research paper thumbnail of Multicentre performance evaluation of the E170 Module for MODULAR ANALYTICS

Clinical Chemistry and Laboratory Medicine, 2000

The E170 module was evaluated at 13 sites in an international multicentre study. The objective of... more The E170 module was evaluated at 13 sites in an international multicentre study. The objective of the study was to assess the analytical performance of 49 analytes, and to collect feedback on the system&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s reliability and practicability. The typical, within-run coefficients of variation (CVs) for most of the quantitative assays ranged between 1 and 2% while a range of 2-4% was achieved with the infectious disease methods. Total precision CVs were found to be within the manufacturer&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s expected performance ranges, demonstrating good concordance of the system&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s measuring channels and a high reproducibility during the 2-4-week trial period. The functional sensitivity of 11 selected assays met the clinical requirements (e.g., thyreotroponin (TSH) 0.008 mU/l, troponin T 0.02 microg/l, total prostate-specific antigen (PSA) 0.03 microg/l). The E170 showed no drift during an 8-hour period and no relevant reagent carryover. Accuracy was confirmed by ring trial experiments and method comparisons vs. Elecsys 2010. The reliability and practicability of the system&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s hardware and software met with, or even exceeded, the evaluator&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s requirements. Workflow studies showed that E170 can cover the combined workload of various routine analysers in a variety of laboratory environment. Throughput and sample processing time requirements were achieved while personnel &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;hands-on-time&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; could be reduced.

Research paper thumbnail of From biomarkers to medical tests: The changing landscape of test evaluation

Clinica Chimica Acta, 2014

Regulators and healthcare payers are increasingly demanding evidence that biomarkers deliver pati... more Regulators and healthcare payers are increasingly demanding evidence that biomarkers deliver patient benefits to justify their use in clinical practice. Laboratory professionals need to be familiar with these evidence requirements to better engage in biomarker research and decisions about their appropriate use. This paper by a multidisciplinary group of the European Federation of Clinical Chemistry and Laboratory Medicine describes the pathway of a laboratory assay measuring a biomarker to becoming a medically useful test. We define the key terms, principles and components of the test evaluation process. Unlike previously described linearly staged models, we illustrate how the essential components of analytical and clinical performances, clinical and cost-effectiveness and the broader impact of testing assemble in a dynamic cycle. We highlight the importance of defining clinical goals and how the intended application of the biomarker in the clinical pathway should drive each component of test evaluation. This approach emphasizes the interaction of the different components, and that clinical effectiveness data should be fed back to refine analytical and clinical performances to achieve improved outcomes. The framework aims to support the understanding of key stakeholders. The laboratory profession needs to strengthen collaboration with industry and experts in evidence-based medicine, regulatory bodies and policy makers for better decisions about the use of new and existing medical tests.

Research paper thumbnail of Setting analytical performance specifications based on outcome studies – is it possible?

Clinical Chemistry and Laboratory Medicine (CCLM), 2015

The 1st Strategic Conference of the European Federation of Clinical Chemistry and Laboratory Medi... more The 1st Strategic Conference of the European Federation of Clinical Chemistry and Laboratory Medicine proposed a simplified hierarchy for setting analytical performance specifications (APS). The top two levels of the 1999 Stockholm hierarchy, i.e., evaluation of the effect of analytical performance on clinical outcomes and clinical decisions have been proposed to be replaced by one outcome-based model. This model can be supported by: (1a) direct outcome studies; and (1b) indirect outcome studies investigating the impact of analytical performance of the test on clinical classifications or decisions and thereby on the probability of patient relevant clinical outcomes. This paper reviews the need for outcome-based specifications, the most relevant types of outcomes to be considered, and the challenges and limitations faced when setting outcome-based APS. The methods of Model 1a and b are discussed and examples are provided for how outcome data can be translated to APS using the linked evidence and simulation or decision analytic techniques. Outcome-based APS should primarily reflect the clinical needs of patients; should be tailored to the purpose, role and significance of the test in a well defined clinical pathway; and should be defined at a level that achieves net health benefit for patients at reasonable costs. Whilst it is acknowledged that direct evaluations are difficult and may not be possible for all measurands, all other forms of setting APS should be weighed against that standard, and regarded as approximations. Better definition of the relationship between the analytical performance of tests and health outcomes can be used to set analytical performance criteria that aim to improve the clinical and cost-effectiveness of laboratory tests.