The Statistical Structure of the Hippocampal Code for Space as a Function of Time, Context, and Value.

Hippocampal activity represents many behaviorally important variables, including context, an animal's location within a given environmental context, time, and reward. Using longitudinal calcium imaging in mice, multiple large virtual environments, and differing reward contingencies, we derived a unified probabilistic model of CA1 representations centered on a single feature-the field propensity. Each cell's propensity governs how many place fields it has per unit space, predicts its reward-related activity, and is preserved across distinct environments and over months. Propensity is broadly distributed-with many low, and some very high, propensity cells-and thus strongly shapes hippocampal representations. This results in a range of spatial codes, from sparse to dense. Propensity varied ∼10-fold between adjacent cells in salt-and-pepper fashion, indicating substantial functional differences within a presumed cell type. Intracellular recordings linked propensity to cell excitability. The stability of each cell's propensity across conditions suggests this fundamental property has anatomical, transcriptional, and/or developmental origins.

Near-Perfect Synaptic Integration by Nav1.7 in Hypothalamic Neurons Regulates Body Weight.

Neurons are well suited for computations on millisecond timescales, but some neuronal circuits set behavioral states over long time periods, such as those involved in energy homeostasis. We found that multiple types of hypothalamic neurons, including those that oppositely regulate body weight, are specialized as near-perfect synaptic integrators that summate inputs over extended timescales. Excitatory postsynaptic potentials (EPSPs) are greatly prolonged, outlasting the neuronal membrane time-constant up to 10-fold. This is due to the voltage-gated sodium channel Nav1.7 (Scn9a), previously associated with pain-sensation but not synaptic integration. Scn9a deletion in AGRP, POMC, or paraventricular hypothalamic neurons reduced EPSP duration, synaptic integration, and altered body weight in mice. In vivo whole-cell recordings in the hypothalamus confirmed near-perfect synaptic integration. These experiments show that integration of synaptic inputs over time by Nav1.7 is critical for body weight regulation and reveal a mechanism for synaptic control of circuits regulating long term homeostatic functions.

The Anatomy and Physiology of Claustrum-Cortex Interactions.

The claustrum is one of the most widely connected regions of the forebrain, yet its function has remained obscure, largely due to the experimentally challenging nature of targeting this small, thin, and elongated brain area. However, recent advances in molecular techniques have enabled the anatomy and physiology of the claustrum to be studied with the spatiotemporal and cell type-specific precision required to eventually converge on what this area does. Here we review early anatomical and electrophysiological results from cats and primates, as well as recent work in the rodent, identifying the connectivity, cell types, and physiological circuit mechanisms underlying the communication between the claustrum and the cortex. The emerging picture is one in which the rodent claustrum is closely tied to frontal/limbic regions and plays a role in processes, such as attention, that are associated with these areas.

Inhibition of mTORC1 by astrin and stress granules prevents apoptosis in cancer cells.

Mammalian target of rapamycin complex 1 (mTORC1) controls growth and survival in response to metabolic cues. Oxidative stress affects mTORC1 via inhibitory and stimulatory inputs. Whereas downregulation of TSC1-TSC2 activates mTORC1 upon oxidative stress, the molecular mechanism of mTORC1 inhibition remains unknown. Here, we identify astrin as an essential negative mTORC1 regulator in the cellular stress response. Upon stress, astrin inhibits mTORC1 association and recruits the mTORC1 component raptor to stress granules (SGs), thereby preventing mTORC1-hyperactivation-induced apoptosis. In turn, balanced mTORC1 activity enables expression of stress factors. By identifying astrin as a direct molecular link between mTORC1, SG assembly, and the stress response, we establish a unifying model of mTORC1 inhibition and activation upon stress. Importantly, we show that in cancer cells, apoptosis suppression during stress depends on astrin. Being frequently upregulated in tumors, astrin is a potential clinically relevant target to sensitize tumors to apoptosis.

A 62-minute orbital period black widow binary in a wide hierarchical triple.

Over a dozen millisecond pulsars are ablating low-mass companions in close binary systems. In the original 'black widow', the eight-hour orbital period eclipsing pulsar PSR J1959+2048 (PSR B1957+20)1, high-energy emission originating from the pulsar2 is irradiating and may eventually destroy3 a low-mass companion. These systems are not only physical laboratories that reveal the interesting results of exposing a close companion star to the relativistic energy output of a pulsar, but are also believed to harbour some of the most massive neutron stars4, allowing for robust tests of the neutron star equation of state. Here we report observations of ZTF J1406+1222, a wide hierarchical triple hosting a 62-minute orbital period black widow candidate, the optical flux of which varies by a factor of more than ten. ZTF J1406+1222 pushes the boundaries of evolutionary models5, falling below the 80-minute minimum orbital period of hydrogen-rich systems. The wide tertiary companion is a rare low-metallicity cool subdwarf star, and the system has a Galactic halo orbit consistent with passing near the Galactic Centre, making it a probe of formation channels, neutron star kick physics6 and binary evolution.

Characterization of naked mole-rat hematopoiesis reveals unique stem and progenitor cell patterns and neotenic traits.

Naked mole rats (NMRs) are the longest-lived rodents yet their stem cell characteristics remain enigmatic. Here, we comprehensively mapped the NMR hematopoietic landscape and identified unique features likely contributing to longevity. Adult NMRs form red blood cells in spleen and marrow, which comprise a myeloid bias toward granulopoiesis together with decreased B-lymphopoiesis. Remarkably, youthful blood and marrow single-cell transcriptomes and cell compositions are largely maintained until at least middle age. Similar to primates, the primitive stem and progenitor cell (HSPC) compartment is marked by CD34 and THY1. Stem cell polarity is seen for Tubulin but not CDC42, and is not lost until 12 years of age. HSPC respiration rates are as low as in purified human stem cells, in concert with a strong expression signature for fatty acid metabolism. The pool of quiescent stem cells is higher than in mice, and the cell cycle of hematopoietic cells is prolonged. By characterizing the NMR hematopoietic landscape, we identified resilience phenotypes such as an increased quiescent HSPC compartment, absence of age-related decline, and neotenic traits likely geared toward longevity.

The epithelial polarity axis controls the resting membrane potential and Cl- co-transport in breast glandular structures.

The membrane potential (MP) controls cell homeostasis by directing molecule transport and gene expression. How the MP is set upon epithelial differentiation is unknown. Given that tissue architecture also controls homeostasis, we investigated the relationship between basoapical polarity and resting MP in three-dimensional culture of the HMT-3522 breast cancer progression. A microelectrode technique to measure MP and input resistance reveals that the MP is raised by gap junction intercellular communication (GJIC), which directs tight-junction mediated apical polarity, and is decreased by the Na+/K+/2Cl- (NKCC, encoded by SLC12A1 and SLC12A2) co-transporter, active in multicellular structures displaying basal polarity. In the tumor counterpart, the MP is reduced. Cancer cells display diminished GJIC and do not respond to furosemide, implying loss of NKCC activity. Induced differentiation of cancer cells into basally polarized multicellular structures restores widespread GJIC and NKCC responses, but these structures display the lowest MP. The absence of apical polarity, necessary for cancer onset, in the non-neoplastic epithelium is also associated with the lowest MP under active Cl- transport. We propose that the loss of apical polarity in the breast epithelium destabilizes cellular homeostasis in part by lowering the MP.

GelMap: intrinsic calibration and deformation mapping for expansion microscopy.

Expansion microscopy (ExM) is a powerful technique to overcome the diffraction limit of light microscopy by physically expanding biological specimen in three dimensions. Nonetheless, using ExM for quantitative or diagnostic applications requires robust quality control methods to precisely determine expansion factors and to map deformations due to anisotropic expansion. Here we present GelMap, a flexible workflow to introduce a fluorescent grid into pre-expanded hydrogels that scales with expansion and reports deformations. We demonstrate that GelMap can be used to precisely determine the local expansion factor and to correct for deformations without the use of cellular reference structures or pre-expansion ground-truth images. Moreover, we show that GelMap aids sample navigation for correlative uses of expansion microscopy. Finally, we show that GelMap is compatible with expansion of tissue and can be readily implemented as a quality control step into existing ExM workflows.

Carbon isotope fractionation by an ancestral rubisco suggests that biological proxies for CO2 through geologic time should be reevaluated.

The history of Earth's carbon cycle reflects trends in atmospheric composition convolved with the evolution of photosynthesis. Fortunately, key parts of the carbon cycle have been recorded in the carbon isotope ratios of sedimentary rocks. The dominant model used to interpret this record as a proxy for ancient atmospheric CO2 is based on carbon isotope fractionations of modern photoautotrophs, and longstanding questions remain about how their evolution might have impacted the record. Therefore, we measured both biomass (εp) and enzymatic (εRubisco) carbon isotope fractionations of a cyanobacterial strain (Synechococcus elongatus PCC 7942) solely expressing a putative ancestral Form 1B rubisco dating to ≫1 Ga. This strain, nicknamed ANC, grows in ambient pCO2 and displays larger εp values than WT, despite having a much smaller εRubisco (17.23 ± 0.61‰ vs. 25.18 ± 0.31‰, respectively). Surprisingly, ANC εp exceeded ANC εRubisco in all conditions tested, contradicting prevailing models of cyanobacterial carbon isotope fractionation. Such models can be rectified by introducing additional isotopic fractionation associated with powered inorganic carbon uptake mechanisms present in Cyanobacteria, but this amendment hinders the ability to accurately estimate historical pCO2 from geological data. Understanding the evolution of rubisco and the CO2 concentrating mechanism is therefore critical for interpreting the carbon isotope record, and fluctuations in the record may reflect the evolving efficiency of carbon fixing metabolisms in addition to changes in atmospheric CO2.

An integrated analysis of bile acid metabolism in humans with severe obesity.

BACKGROUND AND AIMS: Bile acids (BA) are vital regulators of metabolism. BAs are AQ6 secreted in the small intestine, reabsorbed, and transported back to the liver, where they can modulate metabolic functions. There is a paucity of data regarding the portal BA composition in humans. This study aimed to address this knowledge gap by investigating portal BA composition and the relation with peripheral and fecal BA dynamics in conjunction with the gut microbiome. APPROACH AND RESULTS: Thirty-three individuals from the BARIA cohort were included. Portal plasma, peripheral plasma, and feces were collected. BA and C4 levels were measured employing mass spectrometry. FGF19 was measured using ELISA. Gut microbiota composition was determined through metagenomics analysis on stool samples. Considerable diversity in the portal BA composition was observed. The majority (n = 26) of individuals had a 9-fold higher portal than peripheral BA concentration. In contrast, 8 individuals showed lower portal BA concentration compared with peripheral and had higher levels of unconjugated and secondary BA in this compartment, suggesting more distal origin. The altered portal BA profile was associated with altered gut microbiota composition. In particular, taxa within Bacteroides were reduced in abundance in the feces of these individuals. CONCLUSIONS: Characterization of the portal BA composition in relation to peripheral and fecal BA increased insight into the dynamics of BA metabolism in individuals with obesity. Peripheral BA composition was much more diverse due to microbial metabolism. About 24% of the portal samples was surprisingly low in total BA; the underlying mechanism requires further exploration.

Diacylglycerols and Lysophosphatidic Acid, Enriched on Lipoprotein(a), Contribute to Monocyte Inflammation.

BACKGROUND: Oxidized phospholipids play a key role in the atherogenic potential of lipoprotein(a) (Lp[a]); however, Lp(a) is a complex particle that warrants research into additional proinflammatory mediators. We hypothesized that additional Lp(a)-associated lipids contribute to the atherogenicity of Lp(a). METHODS: Untargeted lipidomics was performed on plasma and isolated lipoprotein fractions. The atherogenicity of the observed Lp(a)-associated lipids was tested ex vivo in primary human monocytes by RNA sequencing, ELISA, Western blot, and transendothelial migratory assays. Using immunofluorescence staining and single-cell RNA sequencing, the phenotype of macrophages was investigated in human atherosclerotic lesions. RESULTS: Compared with healthy individuals with low/normal Lp(a) levels (median, 7 mg/dL [18 nmol/L]; n=13), individuals with elevated Lp(a) levels (median, 87 mg/dL [218 nmol/L]; n=12) demonstrated an increase in lipid species, particularly diacylglycerols (DGs) and lysophosphatidic acid (LPA). DG and the LPA precursor lysophosphatidylcholine were enriched in the Lp(a) fraction. Ex vivo stimulation with DG(40:6) demonstrated a significant upregulation in proinflammatory pathways related to leukocyte migration, chemotaxis, NF-κB (nuclear factor kappa B) signaling, and cytokine production. Functional assessment showed a dose-dependent increase in the secretion of IL (interleukin)-6, IL-8, and IL-1ß after DG(40:6) and DG(38:4) stimulation, which was, in part, mediated via the NLRP3 (NOD [nucleotide-binding oligomerization domain]-like receptor family pyrin domain containing 3) inflammasome. Conversely, LPA-stimulated monocytes did not exhibit an inflammatory phenotype. Furthermore, activation of monocytes by DGs and LPA increased their transendothelial migratory capacity. Human atherosclerotic plaques from patients with high Lp(a) levels demonstrated colocalization of Lp(a) with M1 macrophages, and an enrichment of CD68+IL-18+TLR4+ (toll-like receptor) TREM2+ (triggering receptor expressed on myeloid cells) resident macrophages and CD68+CASP1+ (caspase) IL-1B+SELL+ (selectin L) inflammatory macrophages compared with patients with low Lp(a). Finally, potent Lp(a)-lowering treatment (pelacarsen) resulted in a reduction in specific circulating DG lipid subspecies in patients with cardiovascular disease with elevated Lp(a) levels (median, 82 mg/dL [205 nmol/L]). CONCLUSIONS: Lp(a)-associated DGs and LPA have a potential role in Lp(a)-induced monocyte inflammation by increasing cytokine secretion and monocyte transendothelial migration. This DG-induced inflammation is, in part, NLRP3 inflammasome dependent.

Temperature-dependence of regional heterothermy in a diminutive ectotherm.

Regional heterothermy describes when body regions differ in temperature, which can have important ramifications for performance because most biological processes are temperature-dependent. However, the relationship between regional heterothermy and environmental temperature is not well known, particularly for ectotherms. The relationship between environmental heterogeneity and regional heterothermy might also yield insight into how the latter is regulated. We examined the thermal dependence of regional heterothermy (between the head and the cloaca) in live ring-necked snakes (Diadophis punctatus) in both the lab and the field, as well as in one dead and preserved individual. We found that the magnitude of the head-cloaca difference declined with average environmental temperature, that the relationship between head temperature and ambient temperature differed from that of cloaca temperature and ambient temperature, and that the preserved snake specimen did not display a consistent head-cloaca temperature difference. Our results suggest that 1) cloacal and head temperatures are regulated differently, 2) the head-cloaca temperature difference is not merely due to differences in the material properties of the head and cloaca, and 3) may arise from altered circulation and perhaps even endogenous heat-generating mechanisms. Our results also suggest that the thermal dependence of regional heterothermy likely has ramifications for organismal function.

Linkage Mapping and Genome-Wide Association Study Identified Two Peanut Late Leaf Spot Resistance Loci, PLLSR-1 and PLLSR-2, Using Nested Association Mapping.

Identification of candidate genes and molecular markers for late leaf spot (LLS) disease resistance in peanut (Arachis hypogaea) has been a focus of molecular breeding for the U.S. industry-funded peanut genome project. Efforts have been hindered by limited mapping resolution due to low levels of genetic recombination and marker density available in traditional biparental mapping populations. To address this, a multi-parental nested association mapping population has been genotyped with the peanut 58K single-nucleotide polymorphism (SNP) array and phenotyped for LLS severity in the field for 3 years. Joint linkage-based quantitative trait locus (QTL) mapping identified nine QTLs for LLS resistance with significant phenotypic variance explained up to 47.7%. A genome-wide association study identified 13 SNPs consistently associated with LLS resistance. Two genomic regions harboring the consistent QTLs and SNPs were identified from 1,336 to 1,520 kb (184 kb) on chromosome B02 and from 1,026.9 to 1,793.2 kb (767 kb) on chromosome B03, designated as peanut LLS resistance loci, PLLSR-1 and PLLSR-2, respectively. PLLSR-1 contains 10 nucleotide-binding site leucine-rich repeat disease resistance genes. A nucleotide-binding site leucine-rich repeat disease resistance gene, Arahy.VKVT6A, was also identified on homoeologous chromosome A02. PLLSR-2 contains five significant SNPs associated with five different genes encoding callose synthase, pollen defective in guidance protein, pentatricopeptide repeat, acyl-activating enzyme, and C2 GRAM domains-containing protein. This study highlights the power of multi-parent populations such as nested association mapping for genetic mapping and marker-trait association studies in peanuts. Validation of these two LLS resistance loci will be needed for marker-assisted breeding.

Domain specific mutations in dyskerin disrupt 3' end processing of scaRNA13.

Mutations in DKC1 (encoding dyskerin) cause telomere diseases including dyskeratosis congenita (DC) by decreasing steady-state levels of TERC, the non-coding RNA component of telomerase. How DKC1 mutations variably impact numerous other snoRNAs remains unclear, which is a barrier to understanding disease mechanisms in DC beyond impaired telomere maintenance. Here, using DC patient iPSCs, we show that mutations in the dyskerin N-terminal extension domain (NTE) dysregulate scaRNA13. In iPSCs carrying the del37L NTE mutation or engineered to carry NTE mutations via CRISPR/Cas9, but not in those with C-terminal mutations, we found scaRNA13 transcripts with aberrant 3' extensions, as seen when the exoribonuclease PARN is mutated in DC. Biogenesis of scaRNA13 was rescued by repair of the del37L DKC1 mutation by genome-editing, or genetic or pharmacological inactivation of the polymerase PAPD5, which counteracts PARN. Inspection of the human telomerase cryo-EM structure revealed that in addition to mediating intermolecular dyskerin interactions, the NTE interacts with terminal residues of the associated snoRNA, indicating a role for this domain in 3' end definition. Our results provide mechanistic insights into the interplay of dyskerin and the PARN/PAPD5 axis in the biogenesis and accumulation of snoRNAs beyond TERC, broadening our understanding of ncRNA dysregulation in human diseases.

Comparison of Speech Outcomes Between Speech Therapy Only and Double-Opposing Z-Plasty Combined With Speech Therapy in Patients With Submucous Cleft Palate.

The purpose of this study was to compare speech outcomes in patients with submucous cleft palate (SMCP) between speech therapy alone and double-opposing Z-plasty (DOZ) combined with speech therapy. The subjects were 67 patients with SMCP (overt type, 45 males, 22 females), who were divided into the observation group (n=18), the speech therapy group (n=24; duration, 17.8 mo), and the DOZ and speech therapy (DOZ-speech therapy) group (n=25; median age at DOZ, 5.3 years, duration, 18.6 mo). The median age at initial and final speech assessments were 3 and 5 years. After age, sex, syndromic status, duration of speech therapy, surgery timing, and speech outcomes were investigated, statistical analysis was performed. After tailored interventions, both isolated and non-isolated SMCP patients experienced significant improvements in speech outcomes, including nasal emission, hypernasality, compensatory articulation, and unintelligible speech. Since comparable improvements were observed, there were no significant differences in the final assessments regardless of initial speech issues between the speech therapy group and the DOZ-speech therapy group (all P>0.05). In the DOZ-speech therapy group, the rate of achieving "socially acceptable" speech was 92.3% in isolated cases and 90% in non-isolated cases. Multivariate analysis revealed that DOZ showed a tendency to reduce hypernasality, compensatory articulation, and "unintelligible" speech; syndromic or developmental conditions influenced outcomes in nasal emission and hypernasality; and initial hypernasality and compensatory articulation were correlated with outcomes. Therefore, DOZ surgery could be recommended to resolve hypernasality and compensatory articulation in SMCP patients before speech issues worsen.

Pharyngeal Arches, Chapter 2: Ear and Neck Abnormalities.

The pharyngeal arches are the foundation of face and neck development. Impaired development of these embryologic structures can result in craniofacial abnormalities. Surgeons who manage head and neck pathology will invariably encounter conditions associated with aberrant pharyngeal arch anatomy, and a thorough understanding of the normal development of these structures is paramount to accurate diagnosis and treatment. This manuscript is the second of a four-part series written for plastic surgeons, focusing on the abnormal development of pharyngeal arches leading to pathologic ear and neck anomalies seen in clinical practice.

Identifying Risk Factors for Wound Complications Following Fronto-Orbital Advancement in Patients With Craniosynostosis: 3-dimensional Craniometrics Analysis.

This study aims to identify 3-dimensional (3D) craniometric predictors of wound complications following fronto-orbital advancement (FOA) surgery in craniosynostosis patients. The authors conducted a retrospective review of medical records for 43 patients (25 female, 18 male) who underwent open FOA between 2006 and 2023, with an average follow-up duration of 91.8 months. The data collected included age at surgery, sex, whether the craniosynostosis was syndromic, involvement of multiple sutures, history of suturectomy, wound complications (categorized as minor or major), and preoperative and postoperative 3D CT scans. The authors quantified relative changes in intracranial volume (ICV), cranial area above the Frankfurt Horizontal plane, anteroposterior diameter (APD), and cranial height (CH) using Mimics software. A logistic regression analysis was performed to identify predictors of wound complications post-FOA. Among the 43 patients who underwent FOA, 10 experienced postoperative wound complications (4 minor, 6 major), revealing significant associations with multisuture involvement and changes in △cranial area, △APD, and △CH (all P<0.05). In the multivariable analysis with backward elimination, △cranial area, and △CH were identified as significant risk factors for wound complications (OR 1.17, 95% CI: 1.01-1.36, P=0.032; and OR 0.59, 95% CI: 0.38-0.92, P=0.019, respectively). The cutoff values for △cranial area and △APD were 5.95% and 7.93%, respectively. This study identified measurable craniometric changes, especially in the cranial area, as risk factors for wound complications following FOA. It underscores the necessity for personalized surgical planning and meticulous postoperative wound care in FOA to enhance patient outcomes through risk-aware strategies.

Socioeconomic Influence on Surgical Management and Outcomes in Patients with Craniosynostosis - A Systematic Review.

OBJECTIVE: Disparities in insurance and socioeconomic status (SES) may impact surgical management and subsequent postoperative outcomes for patients with craniosynostosis. This systematic review summarizes the evidence on possible differences in surgical care, including procedure type, age at surgery, and differences in surgical outcomes such as complications, length of hospital stay, and child development based on SES. DESIGN: The databases Scopus, PubMed, and CINAHL were searched between May and July 2022. Following PICO criteria, studies included focused on patients diagnosed with craniosynostosis; corrective surgery for craniosynostosis; comparison of insurance, income, or zip code; and surgical management of postoperative outcomes. RESULTS: The initial search yielded 724 articles. After three stages of screening, 13 studies were included. Assessed outcomes included: type of procedure (6 articles), age at time of surgery (3 articles), post-operative complications (3 articles), referral delay (2 articles), length of stay (2 articles), hospital costs (2 articles), and child development (1 article). Of the studies with significant results, insurance type was the main SES variable of comparison. While some findings were mixed, these studies indicated that patients with public medical insurance were more likely to experience a delay in referral, undergo an open rather than minimally-invasive procedure, and have more complications, longer hospitalization, and higher medical charges. CONCLUSIONS: This study demonstrated that SES may be associated with several differences in the management of patients with craniosynostosis. Further investigation into the impact of SES on the management of patients with craniosynostosis is warranted to identify possible interventions that may improve overall care.

Predicting Failure of Conservative Airway Management in Infants with Robin Sequence: The EARN Factors.

OBJECTIVE: Evaluate infants with Robin Sequence (RS) who were successfully treated with conservative airway measures alone vs. those who failed and eventually underwent surgical airway intervention after a protracted course of conservative management. DESIGN: Retrospective review of prospectively gathered database. SETTING: Large tertiary care institution. PATIENTS: Infants diagnosed with RS (n = 122) who underwent primary airway management at a single institution from 1994-2020. MAIN OUTCOME MEASURE: Patient demographics, nutritional and respiratory status, laboratory values, and polysomnographic results were compared between patients who were discharged after successful conservative airway management (Group 1, n = 61) and patients that underwent surgical airway intervention after failing a prolonged course of conservative management (Group 2, n = 61). Receiver operating characteristic (ROC) curve analysis was done to assess continuous variables that may predict failure of conservative airway management. RESULTS: 122 infants with RS were investigated. While several variables were significantly different between groups, the following polysomnographic EARN factors, with cut points, were identified as most predictive of failed conservative airway management: ETCO2 (max) > 49 mmHg, AHI > 16.9 events/hour, OAHI REM >25.9 events/hour, OAHI Non-REM > 23.6 events/hour. CONCLUSIONS: We identified factors in infants with RS that were associated with severe UAO that failed to improve despite weeks of conservative airway management. Our results may expedite earlier definitive treatment of these critical patients and reduce risks for known complications of prolonged UAO.

Reference Interval Harmonization: Harnessing the Power of Big Data Analytics to Derive Common Reference Intervals across Populations and Testing Platforms.

BACKGROUND: Harmonization in laboratory medicine is essential for consistent and accurate clinical decision-making. There is significant and unwarranted variation in reference intervals (RIs) used by laboratories for assays with established analytical traceability. The Canadian Society of Clinical Chemists (CSCC) Working Group on Reference Interval Harmonization (hRI-WG) aims to establish harmonized RIs (hRIs) for laboratory tests and support implementation. METHODS: Harnessing the power of big data, laboratory results were collected across populations and testing platforms to derive common adult RIs for 16 biochemical markers. A novel comprehensive approach was established, including: (a) analysis of big data from community laboratories across Canada; (b) statistical evaluation of age, sex, and analytical differences; (c) derivation of hRIs using the refineR method; and (d) verification of proposed hRIs across 9 laboratories with different instrumentation using serum and plasma samples collected from healthy Canadian adults. RESULTS: Harmonized RIs were calculated for all assays using the refineR method, except free thyroxine. Derived hRIs met proposed verification criterion across 9 laboratories and 5 manufacturers for alkaline phosphatase, albumin (bromocresol green), chloride, lactate dehydrogenase, magnesium, phosphate, potassium (serum), and total protein (serum). Further investigation is needed for some analytes due to failure to meet verification criteria in one or more laboratories (albumin [bromocresol purple], calcium, total carbon dioxide, total bilirubin, and sodium) or concern regarding excessively wide hRIs (alanine aminotransferase, creatinine, and thyroid stimulating hormone). CONCLUSIONS: We report a novel data-driven approach for RI harmonization. Findings support feasibility of RI harmonization for several analytes; however, some presented challenges, highlighting limitations that need to be considered in harmonization and big data analytics.