Publications by authors named "Heather A Nelson"

14 Publications

  • Page 1 of 1

Clinical and Analytical Characterization of the DiaSorin and ScheBo Fecal Pancreatic Elastase 1 Assays.

Pancreas 2022 Mar;51(3):243-249

ARUP Laboratories, Salt Lake City, UT.

Objectives: Fecal pancreatic elastase (PE) assays are screening tests for exocrine pancreatic insufficiency (EPI). We analytically evaluated a new PE assay and retrospectively analyzed data from an academic hospital and reference laboratory to understand the clinical utility.

Methods: Forty stool samples with different PE concentrations were tested on the ScheBo enzyme-linked immunosorbent assay (ELISA) versus DiaSorin LIAISON immunoassay; a simple-to-use extraction device was assessed. The cross-reactivity of porcine enzymes was investigated in the immunoassay. Charts of 207 patients with PE results less than 250 μg/g at an academic hospital were reviewed, and data were analyzed for 5136 patients with repeat PE results from a reference laboratory.

Results: The LIAISON immunoassay gave comparable results to the ScheBo ELISA, with 87.5% agreement of PE results in classifying as sufficient, mild/moderate insufficiency, or severe insufficiency. The extraction device worked well compared with manual weighing, and no cross reactivity with porcine enzymes was observed. In agreement with prior studies, our clinical data suggested that PE assays were most useful in detecting severe EPI.

Conclusions: The new DiaSorin LIAISON immunoassay preforms similarly to the well-known ScheBo ELISA. Pancreatic elastase assays can help identify patients with severe EPI but are not as useful in classifying mild/moderate EPI.
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http://dx.doi.org/10.1097/MPA.0000000000002006DOI Listing
March 2022

Clinical Utility and Analytical Aspects of Direct Measurements of Free Hormones Using Mass Spectrometry-Based Methods.

J Appl Lab Med 2022 Mar 17. Epub 2022 Mar 17.

ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT.

Background: The free hormone (FH) hypothesis states that hormone action and the corresponding biological effects are mediated by the unbound (free) fraction of hormone in circulation. The in vivo relationship between protein-bound and FH is complex and dynamic. In most individuals, measurement of total hormone (TH) is usually adequate to reflect the hormone status; however, certain physiological conditions and/or medications can affect protein binding and alter FH concentration. In these cases, measurement of FH will provide a better measure of the bioactive hormone status than measurement of the TH. Measurement of FH presents many challenges, as the concentrations are very low and there are number of pitfalls, which may affect the measured concentrations.

Content: In this review, we discuss techniques used in the separation and direct quantitation of FH concentrations in biological samples using mass spectrometry for analysis. We also highlight clinical situations in which FH analysis is warranted and when mass spectrometry should be the preferred methodology over immunoassays.

Summary: Equilibrium dialysis, ultrafiltration, or size-exclusion separation coupled with liquid chromatography-tandem mass spectrometry provides a sensitive and specific method to measure FH concentrations. These direct methods are useful in iatrogenic or physiological states that alter hormone binding or metabolism.
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http://dx.doi.org/10.1093/jalm/jfac010DOI Listing
March 2022

Mitigation of Biotin Interference in Manual and Automated Immunoassays by Preconjugating Biotinylated Antibodies to the Streptavidin Surface as an Alternative to Biotin Depletion.

J Appl Lab Med 2022 May;7(3):762-775

Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, UT, USA.

Background: Streptavidin-to-biotin binding is one of the strongest noncovalent interactions in nature and incorporated into many immunoassays. Biotin-streptavidin coupling assays are susceptible to interference from free biotin in patient specimens, which may falsely decrease or increase results. To prevent biotin interference, we evaluated a method to preconjugate biotinylated antibodies to the assay's streptavidin solid surface before adding patient specimen and compared this technique to a biotin depletion protocol.

Methods: Biotin interference in 3 manual ELISAs and 2 automated immunoassays was established. Mitigation of biotin interference by preincubation was evaluated in each assay by adding biotinylated antibody to the streptavidin-coated surface before adding biotin- or PBS-spiked serum. Lastly, the preincubation method was compared to a biotin-depletion protocol to compare the effectiveness of mitigating biotin interference.

Results: In the presence of 400 µg/L biotin, analyte detection was reduced to 10% to 15% of total in the ELISA assays and to 15.2% in the automated sandwich (thyroglobulin) immunoassay. In the automated competitive (free thyroxine) immunoassay, biotin caused an increased detection of 551.6%. Preconjugation of the biotinylated capture antibody to the streptavidin surface in the ELISA assays resulted in 84% to 99% activity recovery, compared to 84% to 97% by a biotin depletion protocol. Similarly, automated sandwich and competitive immunoassays obtained 97.1% and 116.5% recovery by preconjugation, compared to 95.6% and 100.3% by the depletion method, respectively.

Conclusion: This study demonstrates how assay redesign to include preconjugation of biotinylated capture antibody to streptavidin is an effective alternative to biotin-depletion methods to mitigate biotin interference.
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http://dx.doi.org/10.1093/jalm/jfab169DOI Listing
May 2022

Mistaken Identity: The Role of Autoantibodies in Endocrine Disease.

J Appl Lab Med 2022 01;7(1):206-220

Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, UT, USA.

Background: Autoimmune endocrine diseases can be thought of as a case of mistaken identity. The immune system mistakenly attacks one's own cells, as if they were foreign, which typically results in endocrine gland hypofunction and inadequate hormone production. Type 1 diabetes mellitus and autoimmune thyroid disorders (Hashimoto and Graves diseases) are the most common autoimmune endocrine disorders, while conditions such as Addison disease are encountered less frequently. Autoantibody production can precede clinical presentation, and their measurement may aid verification of an autoimmune process and guide appropriate treatment modalities.

Content: In this review, we discuss type 1 diabetes mellitus, autoimmune thyroid disorders, and Addison disease, emphasizing their associated autoantibodies and methods for clinical detection. We will also discuss efforts to standardize measurement of autoantibodies.

Conclusions: Autoimmune endocrine disease progression may take months to years and detection of associated autoantibodies may precede clinical onset of disease. Although detection of autoantibodies is not necessary for diagnosis, they may be useful to verify an autoimmune process.
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http://dx.doi.org/10.1093/jalm/jfab128DOI Listing
January 2022

An Interference in an Automated HCO3- Assay Leads to an Unexpected IgG Monoclonal Gammopathy Diagnosis.

J Appl Lab Med 2022 03;7(2):622-625

Department of Pathology, University of Utah, Salt Lake City, UT, USA.

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http://dx.doi.org/10.1093/jalm/jfab126DOI Listing
March 2022

Hereditary pancreatitis in a young adult: Acute to chronic.

Clin Biochem 2021 Dec 13;98:78-80. Epub 2021 Sep 13.

Department of Pathology and ARUP Laboratories, University of Utah, Salt Lake City, UT, USA. Electronic address:

This report investigates an unusual case of recurrent pancreatitis. A 22-year-old female was admitted to the emergency room for severe abdominal pain, nausea, and weight loss. She reported having these symptoms since she was a toddler. The clinician ordered fecal pancreatic elastase-1, fat-soluble vitamins, molecular studies, and imaging of the pancreas by computed tomography. The screening test result for fecal pancreatic elastase-1 revealed severe pancreatic exocrine insufficiency, and the concentrations of fat-soluble vitamins were also low. Imaging showed scattered calcifications in the pancreas. These findings supported a diagnosis of chronic pancreatitis. Due to the rarity of chronic pancreatitis in young adults, molecular studies were performed. The patient was found to be homozygous for a mutation in the SPINK1 gene, which is associated with hereditary pancreatitis. This case report discusses hereditary pancreatitis and highlights data on the utilization of fecal pancreatic elastase-1 to assess pancreatic exocrine insufficiency.
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http://dx.doi.org/10.1016/j.clinbiochem.2021.09.006DOI Listing
December 2021

Umbilical Cord Drug Screening in Multiple Births: Experience from a Reference Laboratory and Academic Medical Center.

J Anal Toxicol 2021 Jun 24. Epub 2021 Jun 24.

Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.

The objective of this study was to review the results of umbilical cord drug screening in twins and triplets (multiples) to compare drug(s) and/or drug metabolite(s) detected. Results that did not agree between multiples were considered mismatched and were investigated. A retrospective analysis was conducted using de-identified data from a national reference laboratory, and results were compared with data from an academic medical center, where detailed medical chart review was performed. Umbilical cord was analyzed for stimulants, sedatives, opioids, and other drugs and metabolites. For the reference laboratory dataset, 23.3% (n=844) of 3,616 umbilical cords from twins (n=3,550) or triplets (n=66) were positive for one or more drugs and/or metabolites. Of these, mismatched results were identified for thirty-seven sets of twins (2.1%) and no sets of triplets. The most frequent mismatches were found in opioids (n=24), with morphine (n=5) being the most mismatched of any single analyte in the panel. Mismatches for the marijuana metabolite 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (9-COOH-THC) in the reference laboratory dataset occurred in six of 737 sets of twins (0.8%) and no triplets. For the academic medical center dataset, 21.9% (n=57) of 260 umbilical cords tested positive for one or more drugs and/or metabolite(s). Of these, 4 mismatches (3.2%) were identified, including 9-COOH-THC (n=2), phentermine (n=1), and oxycodone (n=1), all involving twins. All involved cases where the discrepant analyte was likely present in the negative twin but either slightly below reporting cutoff threshold, or failed analytical quality criteria. Mismatched results of umbilical cord drug screening occur in less than 4% of twins and most often occur when the analyte is slightly above the reporting cutoff in just one infant.
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http://dx.doi.org/10.1093/jat/bkab077DOI Listing
June 2021

Integrated human pseudoislet system and microfluidic platform demonstrate differences in GPCR signaling in islet cells.

JCI Insight 2020 05 21;5(10). Epub 2020 May 21.

Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.

Pancreatic islets secrete insulin from β cells and glucagon from α cells, and dysregulated secretion of these hormones is a central component of diabetes. Thus, an improved understanding of the pathways governing coordinated β and α cell hormone secretion will provide insight into islet dysfunction in diabetes. However, the 3D multicellular islet architecture, essential for coordinated islet function, presents experimental challenges for mechanistic studies of intracellular signaling pathways in primary islet cells. Here, we developed an integrated approach to study the function of primary human islet cells using genetically modified pseudoislets that resemble native islets across multiple parameters. Further, we developed a microperifusion system that allowed synchronous acquisition of GCaMP6f biosensor signal and hormone secretory profiles. We demonstrate the utility of this experimental approach by studying the effects of Gi and Gq GPCR pathways on insulin and glucagon secretion by expressing the designer receptors exclusively activated by designer drugs (DREADDs) hM4Di or hM3Dq. Activation of Gi signaling reduced insulin and glucagon secretion, while activation of Gq signaling stimulated glucagon secretion but had both stimulatory and inhibitory effects on insulin secretion, which occur through changes in intracellular Ca2+. The experimental approach of combining pseudoislets with a microfluidic system allowed the coregistration of intracellular signaling dynamics and hormone secretion and demonstrated differences in GPCR signaling pathways between human β and α cells.
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http://dx.doi.org/10.1172/jci.insight.137017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7259531PMC
May 2020

Bok regulates mitochondrial fusion and morphology.

Cell Death Differ 2019 12 11;26(12):2682-2694. Epub 2019 Apr 11.

Department of Pharmacology, SUNY Upstate Medical University, 750 E Adams Street, Syracuse, NY, 13210, USA.

Bok (Bcl-2-related ovarian killer) is a member of the Bcl-2 protein family that governs the intrinsic apoptosis pathway, but the cellular role that Bok plays is controversial. Remarkably, endogenous Bok is constitutively bound to inositol 1,4,5-trisphosphate receptors (IPRs) and is stabilized by this interaction. Here we report that despite the strong association with IPRs, deletion of Bok expression by CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein-9 nuclease)-mediated gene editing does not alter calcium mobilization via IPRs or calcium influx into the mitochondria. Rather, Bok deletion significantly reduces mitochondrial fusion rate, resulting in mitochondrial fragmentation. This phenotype is reversed by exogenous wild-type Bok and by an IPR binding-deficient Bok mutant, and may result from a decrease in mitochondrial motility. Bok deletion also enhances mitochondrial spare respiratory capacity and membrane potential. Finally, Bok does not play a major role in apoptotic signaling, since Bok deletion does not alter responsiveness to various apoptotic stimuli. Overall, despite binding to IPRs, Bok does not alter IPR-mediated Ca signaling, but is required to maintain normal mitochondrial fusion, morphology, and bioenergetics.
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http://dx.doi.org/10.1038/s41418-019-0327-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7224202PMC
December 2019

Interplay between ER Ca Binding Proteins, STIM1 and STIM2, Is Required for Store-Operated Ca Entry.

Int J Mol Sci 2018 May 19;19(5). Epub 2018 May 19.

Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA.

Store-operated calcium entry (SOCE), a fundamentally important homeostatic and Ca signaling pathway in many types of cells, is activated by the direct interaction of stromal interaction molecule 1 (STIM1), an endoplasmic reticulum (ER) Ca-binding protein, with Ca-selective Orai1 channels localized in the plasma membrane. While much is known about the regulation of SOCE by STIM1, the role of stromal interaction molecule 2 (STIM2) in SOCE remains incompletely understood. Here, using clustered regularly interspaced short palindromic repeats -CRISPR associated protein 9 (CRISPR-Cas9) genomic editing and molecular imaging, we investigated the function of STIM2 in NIH 3T3 fibroblast and αT3 cell SOCE. We found that deletion of expression reduced SOCE by more than 90% in NIH 3T3 cells. STIM1 expression levels were unaffected in the null cells. However, quantitative confocal fluorescence imaging demonstrated that in the absence of expression, STIM1 did not translocate or form punctae in plasma membrane-associated ER membrane (PAM) junctions following ER Ca store depletion. Fluorescence resonance energy transfer (FRET) imaging of intact, living cells revealed that the formation of STIM1 and Orai1 complexes in PAM nanodomains was significantly reduced in the knockout cells. Our findings indicate that STIM2 plays an essential role in regulating SOCE in NIH 3T3 and αT3 cells and suggests that dynamic interplay between STIM1 and STIM2 induced by ER Ca store discharge is necessary for STIM1 translocation, its interaction with Orai1, and activation of SOCE.
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http://dx.doi.org/10.3390/ijms19051522DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5983841PMC
May 2018

Molecular physiology and pathophysiology of stromal interaction molecules.

Exp Biol Med (Maywood) 2018 03 24;243(5):451-472. Epub 2018 Jan 24.

1 Department of Cell and Developmental Biology, 12302 SUNY Upstate Medical University, Syracuse, NY 13210, USA.

Ca release from the endoplasmic reticulum is an important component of Ca signal transduction that controls numerous physiological processes in eukaryotic cells. Release of Ca from the endoplasmic reticulum is coupled to the activation of store-operated Ca entry into cells. Store-operated Ca entry provides Ca for replenishing depleted endoplasmic reticulum Ca stores and a Ca signal that regulates Ca-dependent intracellular biochemical events. Central to connecting discharge of endoplasmic reticulum Ca stores following G protein-coupled receptor activation with the induction of store-operated Ca entry are stromal interaction molecules (STIM1 and STIM2). These highly homologous endoplasmic reticulum transmembrane proteins function as sensors of the Ca concentration within the endoplasmic reticulum lumen and activators of Ca release-activated Ca channels. Emerging evidence indicates that in addition to their role in Ca release-activated Ca channel gating and store-operated Ca entry, STIM1 and STIM2 regulate other cellular signaling events. Recent studies have shown that disruption of STIM expression and function is associated with the pathogenesis of several diseases including autoimmune disorders, cancer, cardiovascular disease, and myopathies. Here, we provide an overview of the latest developments in the molecular physiology and pathophysiology of STIM1 and STIM2. Impact statement Intracellular Ca signaling is a fundamentally important regulator of cell physiology. Recent studies have revealed that Ca-binding stromal interaction molecules (Stim1 and Stim2) expressed in the membrane of the endoplasmic reticulum (ER) are essential components of eukaryote Ca signal transduction that control the activity of ion channels and other signaling effectors present in the plasma membrane. This review summarizes the most recent information on the molecular physiology and pathophysiology of stromal interaction molecules. We anticipate that the work presented in our review will provide new insights into molecular interactions that participate in interorganelle signaling crosstalk, cell function, and the pathogenesis of human diseases.
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http://dx.doi.org/10.1177/1535370218754524DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5882025PMC
March 2018

Stromal Interaction Molecule 1 (STIM1) Regulates ATP-sensitive Potassium () and Store-operated Ca Channels in MIN6 β-Cells.

J Biol Chem 2017 02 21;292(6):2266-2277. Epub 2016 Dec 21.

From the Department of Medicine and

Stromal interaction molecule 1 (STIM1) regulates store-operated Ca entry (SOCE) and other ion channels either as an endoplasmic reticulum Ca-sensing protein or when present in the plasma membrane. However, the role of STIM1 in insulin-secreting β-cells is unresolved. We report that lowering expression of , the gene that encodes STIM1, in insulin-secreting MIN6 β-cells with RNA interference inhibits SOCE and ATP-sensitive K () channel activation. The effects of knockdown were reversed by transduction of MIN6 cells with an adenovirus gene shuttle vector that expressed human Immunoprecipitation studies revealed that STIM1 binds to nucleotide binding fold-1 (NBF1) of the sulfonylurea receptor 1 (SUR1) subunit of the channel. Binding of STIM1 to SUR1 was enhanced by poly-lysine. Our data indicate that SOCE and channel activity are regulated by STIM1. This suggests that STIM1 is a multifunctional signaling effector that participates in the control of membrane excitability and Ca signaling events in β-cells.
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http://dx.doi.org/10.1074/jbc.M116.767681DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5313099PMC
February 2017

Employing RMR technology in a 90-day weight control program.

Obes Facts 2008 2;1(6):298-304. Epub 2008 Dec 2.

Harold Abel School of Psychology, Capella University, Minneapolis, MN, USA.

Objective: The purpose of this study was to evaluate the efficacy of a weight management program using indirect calorimetry to set energy goals.

Methods: 54 overweight, active duty adult employees of the US Air Force (age 18-46 years, BMI 25.2-35.6 kg/m(2)) participated in this quasi-experimental control design study. All participants were enrolled in a four-session US Air Force 'Sensible Weigh' group weight control program. Treatment participants received a personalized nutrition energy goal message developed using measured resting metabolic rate (RMR) from a hand-held indirect calorimeter (MedGem). Usual care participants received a nutritional message using a standard care equation (25 kcal/day x body weight) to set energy intake goals.

Results: Treatment participants lost significantly more weight than usual care participants (p < or = 0.05). Difference in weight loss between the treatment and usual care group were -4.3 kg +/- 3.3 vs. -1.8 kg +/- 3.2, respectively. There were no significant differences in reported food intake or energy expenditure between groups.

Conclusion: The use of indirect calorimetry to assess RMR and set energy intake goals positively influences weight loss success in overweight Air Force personnel.
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http://dx.doi.org/10.1159/000178026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6452104PMC
January 2010

Downregulation of NF-kappaB activity associated with alteration in proliferative response in the spleen after burn injury.

Shock 2005 Jan;23(1):73-9

Department of Surgery, University of California, Davis, California, USA.

Alterations in proliferation status and cellular composition of immune organs are among key events in the modulation of immune function after burn injury. Nuclear factor (NF)-kappaB is a transcription factor that plays a pivotal role in the response to injury as well as immune cell differentiation and proliferation. In this study, we investigated the effects of burn injury on the activity of NF-kappaB and its association with cellular proliferation in the spleen. Western analysis of whole spleen tissues of mice after 18% burn injury revealed a marked reduction in nuclear NF-kappaB rel A protein expression 3 to 21 days after injury when there was an increase in proliferative activity in the red pulp of the spleen after injury as indicated by an increase in proliferating cell nuclear antigen (PCNA). In the splenic B cells, however, the down-regulation of NF-kappaB rel A was associated with decreased PCNA expression as well as IkappaBalpha and phosphorylated IkappaBalpha. In contrast, no significant change in NF-kappaB rel A or PCNA expression was observed for splenic T cells. These data suggest that there is a differential regulation of NF-kappaB and proliferative activity in the splenic cell subsets after burn injury. Furthermore, the regulation of NF-kappaB may be linked to the proliferative changes seen in the spleen after burn injury.
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http://dx.doi.org/10.1097/01.shk.0000148052.66645.67DOI Listing
January 2005
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