Development of a Rapid Qualitative Screen for Anticoagulant Presence

BACKGROUND

Direct oral anticoagulants (DOACs) and fondaparinux with stable pharmacokinetics are commonly used anticoagulants for outpatient care. Due to the lack of monitoring requirements, drug-specific assays are not available in most hospital laboratories, but drug levels are needed in some urgent/emergency situations. This study describes the development of a qualitative screen for the presence of DOAC or fondaparinux using coagulation tests found in most laboratories.

METHODS

The DOAC screen is composed of a heparin anti-Xa activity assay and thrombin time (TT) assay. The STA®-Liquid-Anti-Xa assay calibrated with Stago Multi Hep® and STA®-TT were run on STA-R Max® analyzers. The anti-Xa activity and TT assays were repeated 5 times in samples of commercially available calibrators and controls for each drug: fondaparinux, dabigatran, rivaroxaban, apixaban, and edoxaban. Statistical analysis and correlations were performed for anti-Xa activity and TT results for each drug and pooled normal plasma.

RESULTS

A significant correlation was found between heparin-calibrated anti-Xa levels and fondaparinux, rivaroxaban, apixiban, and edoxaban (r2 = 0.99-1.0). Dabigatran showed a strong linear correlation (r2 = 0.99) with TT. Anti-Xa levels >0.3 IU/mL and TT >25 seconds were determined as cutoffs at our lab for the detection of clinically relevant drug levels of factor Xa inhibitor and direct thrombin inhibitor, respectively.

CONCLUSIONS

Our study demonstrates that commonly available heparin anti-Xa activity and TT assays can be used to qualitatively detect DOACs and fondaparinux and provides a method to establish a qualitative interpretation.

Paediatric healthcare and hospital worker SARS-CoV-2 IgG antibody: A longitudinal cohort study

Background

This study sought to determine the prevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) nucleocapsid (N) and spike (S) protein immunoglobulin G (IgG) antibodies in healthcare and hospital workers (HCHWs), and changes in IgG N antibody levels over time.

Methods

Longitudinal study of HCHWs at a freestanding, urban paediatric tertiary care hospital. Asymptomatic HCHWs aged ≥18 years working in clinical areas were eligible to enrol. Participants completed four surveys and blood draws over 12 months. Specimens were tested for IgG N at four timepoints and IgG S at 12 months.

Results

In total, 531 HCHWs enrolled in this study; of these, 481 (91%), 429 (81%) and 383 (72%) completed follow-up blood draws at 2, 6 and 12 months, respectively. Five of 531 (1%), 5/481 (1%), 6/429 (1%) and 5/383 (1.3%) participants were seropositive for IgG N at baseline, 2, 6 and 12 months, respectively. All (374/374; 100%) participants who received one or two doses of either mRNA COVID-19 vaccine were seropositive for IgG S. One of nine unvaccinated participants was seropositive for IgG S.

Conclusions

In this paediatric hospital, IgG N and IgG S were detected in 1.9% and 97.9% of HCHWs, respectively. This study demonstrated low transmission of SARS-CoV-2 among HCHWs with appropriate infection prevention measures.

Oral estrogen leads to falsely low concentrations of estradiol in a common immunoassay

OBJECTIVES

Recently, an estradiol immunoassay manufacturer (Beckman Coulter, USA) issued an 'important product notice' alerting clinical laboratories that their assay (Access Sensitive Estradiol) was not indicated for patients undergoing exogenous estradiol treatment. The objective of this analysis was to evaluate immunoassay bias relative to liquid chromatography tandem mass spectrometry (LC-MS/MS) in transgender women and to examine the influence of unconjugated estrone on measurements.

DESIGN

Cross-sectional secondary analysis.

METHODS

Estradiol concentrations from 89 transgender women were determined by 3 immunoassays (Access Sensitive Estradiol ('New BC') and Access Estradiol assays ('Old BC'), Beckman Coulter; Estradiol III assay ('Roche'), Roche Diagnostics) and LC-MS/MS. Bias was evaluated with and without adjustment for estrone concentrations. The number of participants who shifted between three estradiol concentration ranges for each immunoassay vs LC-MS/MS (>300 pg/mL, 70-300 pg/mL, and <70 pg/mL) was calculated.

RESULTS

The New BC assay had the largest magnitude overall bias (median: -34%) and was -40%, -22%, and -10%, among participants receiving tablet, patch, or injection preparations, respectively. Overall bias was -12% and +17% for the Roche and Old BC assays, respectively. When measured with the New BC assay, 18 participants shifted to a lower estradiol concentration range (vs 9 and 10 participants based on Roche or Old BC assays, respectively). Adjustment for estrone did not minimize bias.

CONCLUSIONS

Immunoassay measurement of estradiol in transgender women may lead to falsely decreased concentrations that have the potential to affect management. A multidisciplinary health care approach is needed to ensure if appropriate analytical methods are available.

Small volume retinol binding protein measurement by liquid chromatography-tandem mass spectrometry

BACKGROUND

The measurement of plasma concentrations of retinol binding protein is a component of nutritional assessment in neonatal intensive care. However, serial testing in newborns is hampered by the limited amount of blood that can be sampled. Limitations are most severe with preterm infants, for whom close monitoring may be most important.

METHODS

We developed an assay to quantify retinol binding protein using trypsin digestion and liquid chromatography-tandem mass spectrometry, which requires a serum or plasma volume of 5 µl. Additionally, we validated the method according to current recommendations and performed comparison with a standard nephelometry platform in clinical use.

RESULTS

The assay demonstrated linearity from below 1 mg/dL (0.48 µM) to more than 20 mg/dL (9.7 µM), and an imprecision of 11.8% at 0.43 mg/dL (0.21 µM). The distribution of results observed with the new method was different when compared with nephelometry.

CONCLUSION

Liquid chromatography-tandem mass spectrometry facilitated testing a smaller sample volume, thereby increasing the ability to monitor key nutritional markers in premature infants. The differences in results compared with a commercially-available nephelometric assay revealed questionable results for lower concentrations by immunoassay.

Evaluation of Exome Sequencing Criteria for Hospital Stewardship and Insurance Authorization at a Pediatric Hospital

Context.—

Genomic molecular testing practices in a pediatric tertiary care institution can vary in utility by patient indication.

Objective.—

To evaluate exome sequencing (ES) ordering practices and the effects of applying criteria to support ES stewardship. Exome sequencing can provide molecular diagnostic information for patients with known or suspected genetic diseases, but it is relatively expensive, and the cost is often borne by patients, institutions, and payers.

Design.—

We examined ordering patterns of ES approved by board-certified geneticists at our tertiary pediatric care center, as well as preauthorization outcomes for ES requests. We compared positivity rates among patients by patient phenotype, composite insurance coverage criteria, and insurance preauthorization outcome.

Results.—

Patients who met composite coverage criteria were more likely to receive a positive result from ES compared to patients who did not meet composite coverage criteria, though this trend was not statistically significant. There was no significant difference in ES results between patients who were denied or not denied preauthorization by insurance payers.

Conclusions.—

Insurance payers should consider implementing and/or expanding coverage criteria for ES, and institutions should implement stewardship programs to support appropriate ES practices.

Acute ANCA Vasculitis and Asymptomatic COVID-19

We describe the presentation and diagnosis of a child with newly diagnosed antineutrophil cytoplasmic antibody-associated vasculitis and associated diffuse alveolar hemorrhage who was positive for coronavirus disease 2019 immunoglobulin G antibodies, indicative of a previous asymptomatic infection. Results of multiple polymerase chain reaction tests coinciding with the start of symptoms were negative, indicating that acute infection was not the cause of the patient's symptoms. Coronavirus disease 2019-induced autoimmune diseases have been described in adults, but this case report represents the first case described in a pediatric patient.

Sublingual Estradiol Is Associated with Higher Estrone Concentrations than Transdermal or Injectable Preparations in Transgender Women and Gender Nonbinary Adults

Purpose: Serum hormone profiles among different feminizing gender-affirming hormone therapies (GAHT) are poorly characterized. To address this gap, we described the serum estrogen profiles of three 17β-estradiol preparations, taken with or without an antiandrogen, using a novel liquid chromatography-mass spectrometry (LC-MS/MS) assay in adults taking feminizing GAHT. Methods: This was a secondary analysis of 93 healthy transgender women and gender nonbinary adults taking feminizing GAHT in a prospective cross-sectional study. Eligible participants took 17β-estradiol (sublingual tablet, transdermal patch, or intramuscular/subcutaneous injection) with or without oral spironolactone for ≥12 months before study entry. We determined serum estrone and estradiol concentrations for each hormone preparation and described the association between estrone and (1) clinically relevant estradiol concentration ranges (≤200 and >200 pg/mL) and (2) antiandrogen use. To achieve our objectives, we described our protocol for developing an LC-MS/MS assay to measure estrone and estradiol concentrations. Results: Estrone concentrations were higher among participants taking sublingual 17β-estradiol tablets compared with transdermal or injectable preparations (p < 0.0001). Estradiol concentrations were higher for injectable versus transdermal preparations (p = 0.0201), but both were similar to sublingual tablet concentrations (p > 0.05). Estradiol >200 pg/mL (vs. ≤200 pg/mL) was associated with higher estrone concentrations among participants taking sublingual 17β-estradiol, but not transdermal or injectable 17β-estradiol. We observed no association between spironolactone and estrone concentrations (p > 0.5). Conclusion: Estrone concentrations were higher among transgender women and gender nonbinary adults taking sublingual 17β-estradiol compared with transdermal or injectable preparations. The role of estrone in clinical monitoring and the influence of other antiandrogens (e.g., cyproterone acetate) on the estrogen profile remain to be determined.

Adapting to telemedicine in the COVID-19 era: Feasibility of dried blood spot testing for hemoglobin A1c

BACKGROUND AND AIMS

The COVID-19 pandemic has led to a rapid growth in the use of telemedicine for delivery of ambulatory diabetes care. This study evaluated the feasibility of remote HbA1c monitoring via dried blood spot (DBS) testing to support assessment of glycemic control for telemedicine visits and examined clinical and demographic characteristics associated with patient completion of DBS testing.

METHODS

Providers could place orders for DBS HbA1c 3 weeks prior to telemedicine visits. Feasibility was assessed by examining DBS completion rates, time to completion, and availability of DBS results prior to telemedicine visits. Chi-square tests and Mann Whitney tests were used to assess whether completion rates were associated with participant characteristics.

RESULTS

Of 303 DBS orders placed for telemedicine visits in June 2020, 162 patients completed the DBS test for a completion rate of (53.4%). Average time from collection at home to result being reported was 6.9 (3.8) days. The DBS result was available in 67.6% of patients who completed successful DBS, before the telemedicine clinic visit. HbA1c was lower in the DBS completion group as compared to the non-completion group (8.2% vs. 8.9%, p = 0.01). No other clinical or demographic characteristics were significantly different between the two groups.

CONCLUSION

Remote HbA1c monitoring via DBS is feasible and offers an avenue to support assessment of glycemic control for patients seen via telemedicine. Future work should focus on improving clinic and laboratory processes to support remote DBS collection.

Prevalence of Health Care and Hospital Worker SARS-CoV-2 IgG Antibody in a Pediatric Hospital

OBJECTIVES

Asymptomatic transmission of coronavirus disease 2019 (COVID-19) in health care settings is not well understood. In this study, we aimed to determine the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G (IgG) antibodies in health care and hospital workers (HCHWs) and assess how antibody levels change over time.

METHODS

Cross-sectional study of employed HCHWs at a freestanding, urban pediatric tertiary care hospital. Employed HCHWs ≥18 years old who were asymptomatic and worked in clinical hospital locations were eligible to participate. Participants completed blood draws and surveys at baseline (between May 4, 2020, and June 2, 2020) and 2 months later (between July 6, 2020, and August 7, 2020). Surveys collected demographic information, SARS-CoV-2 exposures, and previous COVID-19 diagnosis.

RESULTS

In total, 530 participants enrolled in and completed baseline study activities. The median age was 37 years (range 19-67 years); 86% identified as female, and 80% identified as white. Two months later, 481 (91%) HCHWs completed another survey and blood draw. Four of 5 (0.9%) seropositive subjects at baseline remained seropositive at 2 months, although 3 had decreasing IgG indices. Five (1.0%) seropositive individuals, including 4 who were previously seropositive and 1 newly seropositive, were detected 2 months later. History of positive SARS-CoV-2 polymerase chain reaction testing results (P < .001) and history of COVID-19 exposure (P < .001) were associated with presence of SARS-CoV-2 antibodies.

CONCLUSIONS

SARS-CoV-2 antibodies were detected in 1% of HCHWs in an urban pediatric hospital in a city with moderate SARS-CoV-2 prevalence. Participants with a known previous COVID-19 diagnosis showed a decline or loss of IgG antibodies over 2 months. These results have implications for identifying those with previous exposure and for ongoing public health recommendations for ensuring workplace safety.

Reproductive Endocrinology Reference Intervals for Transgender Men on Stable Hormone Therapy

BACKGROUND

Gender-affirming therapy with testosterone is commonly prescribed to aid in the masculinization of transgender men. Sex-hormone concentrations are routinely measured, but interpretation of results can be difficult due to the lack of published reference intervals.

METHODS

Healthy transgender individuals who had been prescribed testosterone (n = 82) for at least a year were recruited from internal medicine and primary care clinics that specialize in transgender medical care. Total testosterone and estradiol were measured using immunoassay and mass spectrometry; LH, FSH, SHBG, prolactin, progesterone, anti-Müllerian hormone (AMH), and dehydroepiandrosterone sulfate (DHEAS) were measured using immunoassay; free testosterone was calculated. Reference intervals (central 95%) were calculated according to Clinical Laboratory Standards Institute guidelines.

RESULTS

When evaluating general endocrine laboratory tests in people using masculinizing hormones, reference intervals for cisgender men can be applied for total and free testosterone and SHBG and reference intervals for cisgender women can be applied for prolactin. Reference intervals for estradiol, LH, FSH, AMH, and DHEAS differ from those used for cisgender men and cisgender women, and therefore should be interpreted using intervals specific to the transmasculine population. For testosterone and estradiol, results from immunoassays were clinically equivalent to mass spectrometry.

CONCLUSION

Masculinizing hormones will alter the concentrations of commonly evaluated endocrine hormones. Providers and laboratories should use appropriate reference intervals to interpret the results of these tests.

Serological identification of SARS-CoV-2 infections among children visiting a hospital during the initial Seattle outbreak

Children are strikingly underrepresented in COVID-19 case counts. In the United States, children represent 22% of the population but only 1.7% of confirmed SARS-CoV-2 cases as of April 2, 2020. One possibility is that symptom-based viral testing is less likely to identify infected children, since they often experience milder disease than adults. Here, to better assess the frequency of pediatric SARS-CoV-2 infection, we serologically screen 1,775 residual samples from Seattle Children's Hospital collected from 1,076 children seeking medical care during March and April of 2020. Only one child was seropositive in March, but seven were seropositive in April for a period seroprevalence of ≈1%. Most seropositive children (6/8) were not suspected of having had COVID-19. The sera of seropositive children have neutralizing activity, including one that neutralized at a dilution > 1:18,000. Therefore, an increasing number of children seeking medical care were infected by SARS-CoV-2 during the early Seattle outbreak despite few positive viral tests.

Serological identification of SARS-CoV-2 infections among children visiting a hospital during the initial Seattle outbreak

Children are strikingly underrepresented in COVID-19 case counts1-3. In the United States, children represent 22% of the population but only 1.7% of confirmed SARS-CoV-2 cases1. One possibility is that symptom-based viral testing is less likely to identify infected children, since they often experience milder disease than adults1,4-7. To better assess the frequency of pediatric SARS-CoV-2 infection, we serologically screened 1,775 residual samples from Seattle Children's Hospital collected from 1,076 children seeking medical care during March and April of 2020. Only one child was seropositive in March, but seven were seropositive in April for a period seroprevalence of ≈ 1%. Most seropositive children (6/8) were not suspected of having had COVID-19. The sera of seropositive children had neutralizing activity, including one that neutralized at a dilution >1:18,000. Therefore, an increasing number of children seeking medical care were infected by SARS-CoV-2 during the early Seattle outbreak despite few positive viral tests.

Reproductive Endocrinology Reference Intervals for Transgender Women on Stable Hormone Therapy

BACKGROUND

Transgender women and nonbinary people seeking feminizing therapy are often prescribed estrogen as a gender-affirming hormone, which will alter their reproductive hormone axis. Testosterone, estradiol, and other reproductive hormones are commonly evaluated to assess therapy, but reference intervals specific to transgender women have not been established. The objective of this study was to derive reference intervals for commonly measured analytes related to reproductive endocrinology in a cohort of healthy gender nonconforming individuals on stable feminizing hormone therapy.

METHODS

Healthy transgender individuals who had been prescribed estrogen (n = 93) for at least a year were recruited from internal medicine and primary care clinics that specialize in transgender medical care. Total testosterone and estradiol were measured using immunoassay and mass spectrometry; LH, FSH, sex hormone binding globulin, prolactin, progesterone, anti-mullerian hormone (AMH), and dehydroepiandrosterone sulfate (DHEAS) were measured using immunoassay; free testosterone was calculated. Reference intervals (central 95%) were calculated according to Clinical Laboratory Standards Institute guidelines.

RESULTS

The distribution of results for transgender women was different than what would be expected from cisgender men or women across all measurements. Use of spironolactone was associated with changes in the result distribution of AMH, FSH, LH, and progesterone. Compared to liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS), immunoassay was sufficient for the majority of estradiol and total testosterone measurements; free testosterone added little clinical value beyond total testosterone.

CONCLUSION

Reference intervals specific to transgender women should be applied when evaluating reproductive endocrine analytes. Spironolactone is a significant variable for result interpretation of some tests.

Does Provider Specialty Matter?

OBJECTIVES

Multiple practice guidelines discourage indiscriminate use of broad panels of allergen-specific IgE (sIgE) tests due to increased risk of false positives and misinterpretation of results. We provide an analytical framework to identify specialty-specific differences in ordering patterns and effectiveness, which can be used to improve test utilization.

METHODS

Test results from a tertiary pediatric hospital were analyzed by ordering specialty to evaluate size of allergen workups. Positivity rates were analyzed to determine effectiveness in selecting tests with high positive pretest probabilities. Laboratory test menu components were also evaluated.

RESULTS

Our findings demonstrate 29% of sIgE tests are ordered as part of broad workups (>20 sIgE tests/date of service) contrary to the recommended testing approach. Detailed descriptions of ordering patterns and positivity rates are provided.

CONCLUSIONS

This study provides a framework for using a cross-sectional analytical approach to assess test utilization patterns and evaluate components of laboratory testing menus.

Deamidated gliadin peptide in pediatric patients with moderately increased tissue transglutaminase; does it help?

BACKGROUND

Deamidated gliadin peptide (DGP) is a relatively new serologic assay used in diagnosis and monitoring of celiac disease. DGP IgG is recommended by some in pediatric patients <2 y. Use in other pediatric populations is not well established. The utility of the DGP screen (IgG + IgA) in patients with moderate increase of tissue transglutaminase (TTG) IgA has not been studied.

METHODS

Cases between January 2015 and October 2017 in which a patient had TTG IgA greater >19 and <100, DGP screen, and biopsy were collected. Indication for biopsy and diabetes diagnosis were recorded. Of 495 patients screened, 31 met criteria.

RESULTS

The sensitivity and specificity of DGP screen were calculated, and were 87.4% and 56%, respectively; though lower in patients with diabetes.

CONCLUSIONS

The study suggests in patients with moderately increased TTG-IgA, DGP screen lacks specificity and does not provide additional information about whether or not to biopsy.

Characterization of bilirubin interference in three commonly used digoxin assays

BACKGROUND

Due to the narrow therapeutic range of digoxin, determining serum/plasma digoxin concentrations is critical for assessing patients with congestive heart failure, atrial fibrillation, and certain types of arrhythmias. However, digoxin quantification by competitive immunoassays is susceptible to interferences that may alter the accuracy of its measurement in patient plasma. This study aimed to characterize the extent of bilirubin interference in three commonly used digoxin immunoassays.

METHODS

Digoxin concentrations were compared using the Beckman Coulter® Unicel DxI 800, the Vitros® 4600, and the Roche Cobas® 8000 in neat or digoxin-spiked icteric and non-icetric plasma samples. A mixing study was performed to demonstrate how digoxin quantification is affected by bilirubin. An equation was derived that predicts the response of the DxI 800, given known bilirubin and digoxin concentrations.

RESULTS

The DxI reported detectable concentrations of digoxin in high bilirubin samples with no added digoxin, while the Vitros® 4600 and Cobas® 8000 gave virtually undetectable results. Spiking digoxin into samples with elevated bilirubin concentrations resulted in a higher percent recovery for the DxI 800 when compared to the other two platforms. The mixing study also revealed an increase in the percent recovery in the DxI 800, while the Vitros® 4600 and Cobas® 8000 were comparable to the expected concentration of digoxin.

CONCLUSIONS

The DxI 800 is most prone to interference by bilirubin, while the Vitros® 4600 and Cobas® 8000 are relatively unaffected. Icteric samples should be interpreted with caution if digoxin quantification is needed, especially on the DxI 800 assay.

Transforming Laboratory Utilization Review into Laboratory Stewardship: Guidelines by the PLUGS National Committee for Laboratory Stewardship

Appropriate utilization of clinical laboratory services is important for patient care and requires institutional stewardship. Clinical laboratory stewardship programs are dedicated to improving the ordering, retrieval, and interpretation of appropriate laboratory tests. In addition, these programs focus on developing, maintaining, and improving systems to provide proper financial coverage for medically necessary testing. Overall, clinical laboratory stewardship programs help clinicians improve the quality of patient care while reducing costs to patients, hospitals, and health systems. This document, which was created by a new multiinstitutional committee interested in promoting and formalizing laboratory stewardship, summarizes core elements of successful hospital-based clinical laboratory stewardship programs. The core elements will also be helpful for independent commercial clinical laboratories.

Preventing Genetic Testing Order Errors With a Laboratory Utilization Management Program

OBJECTIVES

To characterize error rates for genetic test orders between medical specialties and in different settings by examining detailed order information.

METHODS

We performed a retrospective analysis of a detailed utilization management case database, comprising 2.5 years of data and almost 1,400 genetic test orders. After review by multiple reviewers, we categorized order modifications and cancellations, quantified rates of positive results and order errors, and compared genetics with nongenetics providers and inpatient with outpatient orders.

RESULTS

High cost or problems with preauthorization were the most common reasons for modification and cancellation, respectively. The cancellation rate for nongenetics providers was three times the rate for geneticists, but abnormal result rates were similar between the two groups. The approval rate for inpatient orders was not significantly lower than outpatient orders, and abnormal result rates were similar for these two groups as well. Order error rates were approximately 8% among tests recommended by genetics providers in the inpatient setting, and tests ordered or recommended by nongeneticists had error rates near 5% in both inpatient and outpatient settings.

CONCLUSIONS

Clinicians without specialty training in genetics make genetic test order errors at a significantly higher rate than geneticists. A laboratory utilization management program prevents these order errors from becoming diagnostic errors and reaching the patient.

Quantifying MMA by SLE LC-MS/MS: Unexpected challenges in assay development

OBJECTIVES

Analysis of serum/plasma methylmalonic acid (MMA) is important for the diagnosis and management of methylmalonic acidemia in pediatric populations. This work focuses on developing and validating a liquid chromatography tandem mass spectrometry (LC-MS/MS) method to monitor methylmalonic acidemia using a simple method preparation.

DESIGN AND METHODS

MMA and stable isotope labeled d3-MMA was extracted using supported liquid extraction (SLE). Assay imprecision, bias, linearity, recovery and carryover were determined. The relationship between MMA and propionyl acylcarnitine (C3-acylcarnitine) was also evaluated using historical paired results from 51 unique individuals.

RESULTS

Baseline separation between MMA and succinic acid was completed in 7min. The assay was linear from 0.1 to 500μM. The intra-day and inter-day imprecision CV ranged from 4.1 to 13.2% (0.3 to 526μM) and 5.0 to 15.7% (0.3 to 233μM), respectively. Recovery ranged from 93 to 125%. The correlation with a national reference laboratory LC-MS/MS assay showed a Deming regression of 1.026 and intercept of -1.335. Carryover was determined to be <0.04%. Patient-specific correlation was observed between MMA and C3-acylcarnitine.

CONCLUSION

This report describes the first LC-MS/MS method using SLE for MMA extraction. In addition, we illustrate the challenges encountered during this method development that should be assessed and resolved by any laboratory implementing a SLE LC-MS/MS assay designed to quantify analytes across several orders of magnitude.

Tacrolimus and sirolimus in capillary dried blood spots allows for remote monitoring

Therapeutic drug monitoring of tacrolimus and sirolimus plays a significant role in the clinical follow-up of transplant patients receiving IMS therapy. Success of transplant and favorable patient outcome relies on maintaining adequate therapeutic drug levels. The purpose of this research is to assess the clinical utility of remote collection of DBS for immunosuppressant monitoring and compare the IMS level in paired collections of venous whole blood and DBS. Sirolimus and tacrolimus levels were clinically correlated in capillary blood collected from a finger poke with venous whole blood from pediatric, post-transplant patients. The participants took the dried blood spot card home with them with a pre-addressed, postage-paid envelope and mailed it back to the laboratory. Overall, a small but statistically significant negative bias was observed (-0.6 ng/mL, p = 0.0011). A chart review was performed to assess whether clinical management would have changed, and none of the cases revealed a clinically significant change. Sirolimus in DBS also correlated with venous levels. Overall, a small but statistically negative bias was observed (-0.8 ng/mL, p = 0.029). In summary, analysis of IMS levels in DBS is possible, and the difference noted between capillary and venous blood is within the clinically acceptable limits.

A prospective tool for risk assessment of sendout testing

OBJECTIVE

Errors associated with laboratory testing can cause significant patient harm. Sendout testing refers to tests sent by a primary lab to a reference lab when testing is unavailable at the primary lab. Sendout testing is particularly high risk for patient harm, due to many factors including increased hand-offs, manual processes, and complexity associated with rare, low-volume tests. No published prospective tools exist for sendout risk assessment.

METHODS

A novel prospective tool was developed to assess risk of diagnostic errors involving laboratory sendout testing. This tool was successfully piloted at nine sites.

RESULTS

Marked diversity was noted among survey respondents, particularly in the sections on quality metrics and utilization management. Of note, most sites had committees who managed rules for test ordering, but few places reported enforcing these rules. Only one site claimed to routinely measure the frequency clinicians failed to retrieve test results. An evaluation of the tool indicated that it was both useful and easy to use.

CONCLUSIONS

This tool could be used by other laboratories to identify the areas of highest risk to patients, which in turn may guide them in focusing their quality improvement efforts and resources.

Improving the Value of Costly Genetic Reference Laboratory Testing With Active Utilization Management

Context.—Tests that are performed outside of the ordering institution, send-out tests, represent an area of risk to patients because of complexity associated with sending tests out. Risks related to send-out tests include increased number of handoffs, ordering the wrong or unnecessary test, specimen delays, data entry errors, preventable delays in reporting and acknowledging results, and excess financial liability. Many of the most expensive and most misunderstood tests are send-out genetic tests.

Objective.—To design and develop an active utilization management program to reduce the risk to patients and improve value of genetic send-out tests.

Design.—Send-out test requests that met defined criteria were reviewed by a rotating team of doctoral-level consultants and a genetic counselor in a pediatric tertiary care center.

Results.—Two hundred fifty-one cases were reviewed during an 8-month period. After review, nearly one-quarter of genetic test requests were modified in the downward direction, saving a total of 2% of the entire send-out bill and 19% of the test requests under management. Ultimately, these savings were passed on to patients.

Conclusions.—Implementing an active utilization strategy for expensive send-out tests can be achieved with minimal technical resources and results in improved value of testing to patients.

Two-dimensional capillary electrophoresis: capillary isoelectric focusing and capillary zone electrophoresis with laser-induced fluorescence detection

CIEF and CZE are coupled with LIF detection to create an ultrasensitive 2-D separation method for proteins. In this method, two capillaries are joined through a buffer-filled interface. Separate power supplies control the potential at the injection end of the first capillary and at the interface; the detector is held at ground potential. Proteins are labeled with the fluorogenic reagent Chromeo P503, which preserves the isoelectric point of the labeled protein. The labeled proteins were mixed with ampholytes and injected into the first-dimension capillary. A focusing step was performed with the injection end of the capillary at high pH and the interface at low pH. To mobilize components, the interface was filled with a high pH buffer, which was compatible with the second-dimension separation. A fraction was transferred to the second-dimension capillary for separation. The process of fraction transfer and second dimension separation was repeated two dozen times. The separation produced a spot capacity of 125.

Capillary sieving electrophoresis and micellar electrokinetic capillary chromatography produce highly correlated separation of tryptic digests

We perform 2-D capillary electrophoresis on fluorescently labeled proteins and peptides. Capillary sieving electrophoresis (CSE) was performed in the first dimension and MEKC was performed in the second. A cellular homogenate was labeled with the fluorogenic reagent FQ and separated using the system. This homogenate generated a pair of ridges; the first had essentially constant migration time in the CSE dimension, while the second had essentially constant migration time in the MEKC dimension. In addition, a few spots were scattered through the electropherogram. The same homogenate was digested using trypsin, and then labeled and subjected to the 2-D separation. In this case, the two ridges observed from the original 2-D separation disappeared and were replaced by a set of spots that fell along the diagonal. Those spots were identified using a local-maximum algorithm and each was fit using a 2-D Gaussian surface by an unsupervised nonlinear least squares regression algorithm. The migration times of the tryptic digest components were highly correlated (r=0.862). When the slowest migrating components were eliminated from the analysis, the correlation coefficient improved to r=0.956.

Femtomolar concentration detection limit and zeptomole mass detection limit for protein separation by capillary isoelectric focusing and laser-induced fluorescence detection

Fluorescence tends to produce the lowest detection limits for most forms of capillary electrophoresis. Two issues have discouraged its use in capillary isoelectric focusing. The first issue is fluorescent labeling of proteins. Most labeling reagents react with lysine residues and convert the cationic residue to a neutral or anionic product. At best, these reagents perturb the isoelectric point of the protein. At worse, they convert each protein into hundreds of different fluorescent products that confound analysis. The second issue is the large background signal generated by impurities within commercial ampholytes. This background signal is particularly strong when excited in the blue portion of the spectrum, which is required by many common fluorescent labeling reagents. This paper addresses these issues. For labeling, we employ Chromeo P540, which is a fluorogenic reagent that converts cationic lysine residues to cationic fluorescent products. The reaction products are excited in the green, which reduces the background signal generated by impurities present within the ampholytes. To further reduce the background signal, we photobleach ampholytes with high-power photodiodes. Photobleaching reduced the noise in the ampholyte blank by an order of magnitude. Isoelectric focusing performed with photobleached pH 3-10 ampholytes produced concentration detection limits of 270 +/- 25 fM and mass detection limits of 150 +/- 15 zmol for Chromeo P540 labeled beta-lactoglobulin. Concentration detection limits were 520 +/- 40 fM and mass detection limits were 310 +/- 30 zmol with pH 4-8 ampholytes. A homogenate was prepared from a Barrett's esophagus cell line and separated by capillary isoelectric focusing, reproducibly generating dozens of peaks. The sample taken for the separation was equal to the labeled protein homogenate from three cells.

Reaction of fluorogenic reagents with proteins III. Spectroscopic and electrophoretic behavior of proteins labeled with Chromeo P503

The spectroscopic and electrophoretic properties of proteins labeled with Chromeo P503 were investigated. Its photobleaching characteristics were determined by continually infusing Chromeo P503-labeled alpha-lactalbumin into a sheath-flow cuvette and monitored fluorescence as a function of laser power. The labeled protein is relatively photo-labile with an optimum excitation power of about 2 mW. The unreacted reagent is weakly fluorescent but present at much higher concentration than the labeled protein. The unreacted reagent undergoes photobleaching at a laser power more than an order of magnitude higher than the labeled protein. One-dimensional capillary electrophoresis analysis of Chromeo P503-labeled alpha-lactalbumin produced concentration detection limits (3sigma) of 12 pM and mass detection limits of 0.7 zmol, but with modest theoretical plate counts of 17,000. The reagent was employed for the two-dimensional capillary electrophoresis analysis of a homogenate prepared from a Barrett's esophagus cell line; the separation quality is similar to that produced by 3-(2-furoyl)quinoline-2-carboxaldehyde (FQ), a more commonly used reagent.

Reaction of fluorogenic reagents with proteins I. Mass spectrometric characterization of the reaction with 3-(2-furoyl)quinoline-2-carboxaldehyde, Chromeo P465, and Chromeo P503

3-(2-Furoyl)quinoline-2-carboxaldehyde (FQ), Chromeo P465, and Chromeo P503 are weakly fluorescent reagents that react with primary amines to produce fluorescent products. We studied the reaction of these reagents with alpha-lactalbumin by mass spectrometry. The reaction generated a set of products by the addition of one or more labels to the protein. At room temperature, the reaction was an order of magnitude faster with the Chromeo reagents than with FQ; however, the steady-state labeling efficiency was a factor of two higher for FQ compared with the Chromeo reagents. The relative abundance of the products with FQ usually followed a binomial distribution, which suggests that the labeling sites were uniformly accessible to this reagent. In contrast, the distribution of reaction products with the Chromeo reagents did not follow a binomial distribution for reactions performed in the absence of sodium dodecyl sulfate (SDS); it appears that the protein labeled with the Chromeo reagents refolded into a relatively stable secondary structure that hid some reactive sites. The reaction with the Chromeo reagent did follow the binomial distribution if the protein underwent treatment with 1% SDS at 95 degrees C for 5 min, which apparently disrupts the protein's secondary structure and allowed uniform access to all labeling sites. Chromeo 503 labeled seven of the 13 primary amines in denatured alpha-lactalbumin.

Reaction of fluorogenic reagents with proteins II: capillary electrophoresis and laser-induced fluorescence properties of proteins labeled with Chromeo P465

The fluorogenic reagent Chromeo P465 is considered for the analysis of proteins by capillary electrophoresis with laser-induced fluorescence detection. The reagent was first used to label alpha-lactalbumin; the product was analyzed by capillary zone electrophoresis in a sub-micellar sodium dodecyl sulfate (SDS) buffer. The product generated a set of equally spaced but poorly resolved peaks that formed a broad envelope with a net mobility of 4 x 10(-4)cm(2) V(-1) s(-1). The components of the envelope were presumably protein that had reacted with different numbers of labels. The mobility of these components decreased by roughly 1% with the addition of each label. The signal increased linearly from 1.0 nM to 100 nM alpha-lactalbumin (r(2)=0.99), with a 3sigma detection limit of 70 pM. We then considered the separation of a mixture of ovalbumin, alpha-chymotrypsinogen A, and alpha-lactalbumin labeled with Chromeo P465; unfortunately, baseline resolution was not achieved with a borax/SDS buffer. Better resolution was achieved with N-cyclohexyl-2-aminoethanesulfonic acid/Tris/SDS/dextran capillary sieving electrophoresis; however, dye interactions with this buffer system produced a less than ideal blank.

Chemical cytometry: fluorescence-based single-cell analysis

Cytometry deals with the analysis of the composition of single cells. Flow and image cytometry employ antibody-based stains to characterize a handful of components in single cells. Chemical cytometry, in contrast, employs a suite of powerful analytical tools to characterize a large number of components. Tools have been developed to characterize nucleic acids, proteins, and metabolites in single cells. Whereas nucleic acid analysis employs powerful polymerase chain reaction-based amplification techniques, protein and metabolite analysis tends to employ capillary electrophoresis separation and ultrasensitive laser-induced fluorescence detection. It is now possible to detect yoctomole amounts of many analytes in single cells.

Reproducible two-dimensional capillary electrophoresis analysis of Barrett's esophagus tissues

We have constructed a high-speed, two-dimensional capillary electrophoresis system with a compact and high-sensitivity fluorescence detector. This instrument is used for the rapid and reproducible separations of Barrett's esophagus tissue homogenates. Proteins and biogenic amines are labeled with the fluorogenic reagent 3-(2-furoyl)quinoline-2-carboxaldehyde. Labeled biomolecules are separated sequentially in two capillaries. The first capillary employs capillary sieving electrophoresis using a replaceable sieving matrix. Fractions are successively transferred to a second capillary where they undergo additional separation by micellar electrokinetic capillary chromatography. The comprehensive two-dimensional separation requires 60 min. Within-day migration time reproducibility is better than 1% in both dimensions for the 50 most intense features. Between-day migration time precision is 1.3% for CSE and better than 0.6% for MECC. Biopsies were obtained from the squamous epithelium in the proximal tubular esophagus, Barrett's epithelium from the distal esophagus, and fundus region of the stomach from each of three Barrett's esophagus patients with informed consent. We identified 18 features from the homogenate profiles as biogenic amines and amino acids. For each of the patients, Barrett's biopsies had more than 5 times the levels of phenylalanine and alanine as compared to squamous tissues. The patient with high-grade dysplasia shows the highest concentrations for 13 of the amino acids across all tissue types. Concentrations of glycine are 40 times higher in squamous biopsies compared to Barrett's and fundal biopsies from the patient with high-grade dysplasia. These results suggest that two-dimensional capillary electrophoresis may be of value for the rapid characterization of endoscopic and surgical biopsies.

Using the biological taxonomy to access biological literature with PathBinderH

PathBinderH allows users to make queries that retrieve sentences and the abstracts containing them from PubMed. Another aspect of PathBinderH is that users can specify biological taxa in order to limit searches by mentioning either the specified taxa, or their subordinate taxa, in the biological taxonomy. Although the current project requires this function only for plant taxa, the principle is extensible to the entire taxonomy.

AVAILABILITY

www.plantgenomics.iastate.edu/PathBinderH. Source code and databases on request.

The mitogen-activated protein kinase p38 is necesssary for interleukin 1beta-induced monocyte chemoattractant protein 1 expression by human mesangial cells

Mitogen-activated protein (MAP) kinases have been suggested as potential mediators for interleukin 1beta (IL-1beta)-induced gene activation. This study investigated the role of the MAP kinases p38 and ERK2 in IL-1beta-mediated expression of the chemokine MCP-1 by human mesangial cells. Phosphorylation of p38 kinase, which is necessary for activation, increased significantly after IL-1beta treatment. p38 kinase immunoprecipitated from IL-1beta-treated cells phosphorylated target substrates to a greater extent than p38 kinase from controls. SB 203580, a selective p38 kinase inhibitor, was used to examine the role of p38 kinase in MCP-1 expression. SB 203580 decreased IL-1beta-induced MCP-1 mRNA and protein levels, but did not affect MCP-1 mRNA stability. Because NF-kappaB is necessary for MCP-1 gene expression, the effect of p38 kinase inhibition on IL-1beta induction of NF-kappaB was measured. SB 203580 (up to 25 microM) had no effect on IL-1beta-induced NF-kappaB nuclear translocation or DNA binding activity. Our previous work showed that IL-1beta also activates the MAP kinase ERK2 in human mesangial cells. PD 098059, a selective inhibitor of the ERK activating kinase MEK1, had no effect on IL-1beta-induced MCP-1 mRNA or protein levels, or on IL-1beta activation of NF-kappaB. These data indicate that p38 kinase is necessary for the induction of MCP-1 expression by IL-1beta, but is not involved at the level of cytoplasmic activation of NF-kappaB. In contrast, ERK2 does not mediate IL-1beta induced MCP-1 gene expression.

Interleukin-1beta induction of mitogen-activated protein kinases in human mesangial cells. Role of oxidation

Interleukin-1beta (IL-1beta) significantly influences renal cellular function through the induction of several gene products. The molecular mechanisms involved in gene regulation by IL-1beta are poorly understood; however, the appearance of novel tyrosine phosphoproteins in IL-1beta-treated cells suggests that IL-1beta may function through tyrosine phosphoprotein intermediates. The mitogen-activated protein (MAP) kinases are tyrosine phosphoproteins that could potentially mediate the effects of IL-1beta. Protein tyrosine phosphorylation following IL-1beta treatment may be dependent on redox changes since the IL-1beta receptor is not a protein-tyrosine kinase and oxidation has been shown to induce tyrosine phosphorylation. In this report we demonstrate that conditioning human glomerular mesangial cells with IL-1beta results in the tyrosine phosphorylation and activation of two members of the MAP kinase family, extracellular signal-regulated protein kinase 2 (ERK2) and p54 Jun-NH2-terminal kinase (JNK). This effect of IL-1beta is abrogated by pretreating cells with the antioxidants N-acetyl-L-cysteine or dithiothreitol. Furthermore, the effects of IL-1beta on ERK and JNK activation are reproduced by treating mesangial cells with membrane-permeable oxidants. IL-1beta and oxidants also cause phosphorylation and activation of the upstream ERK regulatory element MAP kinase kinase. Interestingly, IL-1beta, but not exogenous oxidants, causes phosphorylation of the upstream JNK activator, JNK kinase. These data indicate that IL-1beta activates ERK2 through an oxidation-dependent pathway. Exogenous oxidants and IL-1beta activate JNK through different upstream mechanisms; however, antioxidant inhibition of JNK activation indicates that endogenous oxidants may play a role in IL-1beta-induced JNK activation. Thus IL-1beta may affect mesangial cell function by activating MAP kinases, which can then regulate gene transcription. Furthermore, reactive oxygen species released during inflammatory glomerular injury may also affect mesangial function through a MAP kinase signal.

Modulation of IL-1-induced chemokine expression in human mesangial cells through alterations in redox status

The effects of altering intracellular redox potential on interleukin 1 (IL-1)-induced MCP-1 gene expression by human mesangial cells were examined. Thiol containing antioxidants significantly increased cellular glutathione content while decreasing glutathione disulfide levels. These antioxidants inhibited IL-1 induction of MCP-1 mRNA expression. This correlated with a decrease in DNA binding activity of NF-kappa B, a transcription factor thought to be necessary for MCP-1 gene expression. Incubation of mesangial cells with the oxidizing agents diamide or hydrogen peroxide did not upregulate MCP-1 gene expression, and prevented IL-1 induction of MCP-1 mRNA. Oxidants appeared to inhibit the degradation of I kappa B, and the translocation of NF-kappa B to the nucleus. Non-oxidative depletion of intracellular glutathione also attenuated the effects of IL-1 on MCP-1 expression. These data indicate that the intracellular redox potential is a critical determinant of cell activation by IL-1. The observation that both oxidizing and reducing environments are inhibitory suggests that redox changes can affect the IL-1 signal transduction pathway at multiple points.

Activation of nuclear factor-kappa B correlates with MCP-1 expression by human mesangial cells

Emerging evidence suggests that mesangial cell-derived monocyte chemoattractant protein-1 (MCP-1) is a potentially important mediator of glomerular monocyte infiltration. Interleukin-1 beta (IL-1) has been found in glomeruli during inflammation, and is a potent inducer of MCP-1 expression by mesangial cells. Analysis of the promoter region of the human MCP-1 gene demonstrates several putative binding sites for transcription activating factors, including recognition elements for the IL-1-inducible transcription factor, nuclear factor-kappa B (NF-kappa B). This study investigated the role of NF-kappa B in IL-1-induced MCP-1 expression by human mesangial cells. We found that treating mesangial cells with IL-1 resulted in the rapid activation (within 30 min) and nuclear translocation of NF-kappa B. NF-kappa B activation could be blocked by preventing the proteolytic degradation of I kappa B, the cytoplasmic inhibitor of NF-kappa B, with the protease inhibitor tosyl-phe-chloromethylketone (TPCK). Inhibition of NF-kappa B with TPCK correlated with a dose-dependent reduction in IL-1-induced MCP-1 mRNA levels. Conversely, raising intracellular cyclic-AMP levels, or exposing mesangial cells to herbimycin A, treatments that block IL-1-induced MCP-1 mRNA expression, significantly attenuated NF-kappa B activation. Finally, blocking the synthesis of one of the protein subunits of NF-kappa B with an antisense oligonucleotide decreased MCP-1 mRNA levels in response to IL-1. These data suggest that MCP-1 gene transcription may be mediated, in part, by the transcription factor NF-kappa B.

Plasma biotin levels in children with burns and scalds

The plasma concentrations of biotin were measured for up to 49 days after injury in nine children with burns and scalds which involved from 12% to 50% of the surface area of the body. Biotin levels below the minimum of the control range were observed in eight of the nine injured children at some stage during the episode.