Benefits and limitations of genome-wide association studies.

Genome-wide association studies (GWAS) involve testing genetic variants across the genomes of many individuals to identify genotype-phenotype associations. GWAS have revolutionized the field of complex disease genetics over the past decade, providing numerous compelling associations for human complex traits and diseases. Despite clear successes in identifying novel disease susceptibility genes and biological pathways and in translating these findings into clinical care, GWAS have not been without controversy. Prominent criticisms include concerns that GWAS will eventually implicate the entire genome in disease predisposition and that most association signals reflect variants and genes with no direct biological relevance to disease. In this Review, we comprehensively assess the benefits and limitations of GWAS in human populations and discuss the relevance of performing more GWAS.

Research on the purification efficiency and mechanism for road runoff pollutants in pervious concrete with recycled aggregates.

The use of recycled aggregate (RA) in pervious concrete (PC) is a green approach that can effectively mitigate urban waterlogging, excessive RA, and runoff pollution, thereby enhancing the urban ecological environment. This article focuses on the long-term purification efficiency of runoff pollutants by PC at different porosities and RA dosages. Moreover, the purification mechanism of pollutants by recycled aggregate pervious concrete (RAPC) was revealed utilizing particle size analysis, microstructure, and elemental analysis. Finally, the recovery effects of different maintenance approaches on the purification capacity of RAPC were explored. The results indicate that an increase in the RA dosage reduced the effective porosity of PC, thereby decreasing the permeability of RAPC. In addition, PC with a lower porosity demonstrated a slightly greater purification effectiveness for pollutants. However, the utilization of RA significantly enhanced the purification capacity of PC for various pollutants, primarily by leveraging advantages in terms of pore structure, micromorphology, and surface chemical composition. Additionally, RAPC exhibited nearly 100 % retention effectiveness for particles larger than 68.95 µm but relatively lower purification efficiency for particles ranging from 1.541 to 17.11 µm. In particular, it displayed the poorest purification performance for particles with a diameter of 6.396 µm. The surface of RAPC's pore channels exhibited a loose state with high porosity and appeared rough and uneven with numerous pits and grooves. RAPC had a larger surface area and contained more components, such as SiO2, CaCO3, and Al2O3, than regular PC. Therefore, RAPC possessed a higher purification capacity. High-pressure flushing (HPF) and sodium citrate flushing (SCF) under different maintenance frequencies significantly contributed to the recovery of the purification efficiency of RAPC. However, overall, a lower maintenance frequency led to a less favorable recovery effect. Furthermore, SCF had a better recovery effect than HPF.

Evaluating Toronto Hospitals' COVID-19 Visitor Policy Using Accountability for Reasonableness.

In March 2020, the Toronto Region COVID-19 Hospital Operations Table developed a policy to guide visitor restrictions at six hospitals (Toronto Region COVID-19 Hospital Operations Table 2021). We conducted nine interviews with the developers and implementers of the policy based on the accountability for reasonableness (A4R) framework. Participants agreed that the A4R principles were met suggesting fair development and implementation of the policy. However, recurrent themes suggested that the policy disadvantaged those unable to advocate for themselves and that there were unaccounted costs to patients, such as lost time and function. We suggest that visitor policies incorporate equity considerations upfront and predetermine metrics to measure harms to patients.

Peptide Location Fingerprinting Reveals Tissue Region-Specific Differences in Protein Structures in an Ageing Human Organ.

In ageing tissues, long-lived extracellular matrix (ECM) proteins are susceptible to the accumulation of structural damage due to diverse mechanisms including glycation, oxidation and protease cleavage. Peptide location fingerprinting (PLF) is a new mass spectrometry (MS) analysis technique capable of identifying proteins exhibiting structural differences in complex proteomes. PLF applied to published young and aged intervertebral disc (IVD) MS datasets (posterior, lateral and anterior regions of the annulus fibrosus) identified 268 proteins with age-associated structural differences. For several ECM assemblies (collagens I, II and V and aggrecan), these differences were markedly conserved between degeneration-prone (posterior and lateral) and -resistant (anterior) regions. Significant differences in peptide yields, observed within collagen I α2, collagen II α1 and collagen V α1, were located within their triple-helical regions and/or cleaved C-terminal propeptides, indicating potential accumulation of damage and impaired maintenance. Several proteins (collagen V α1, collagen II α1 and aggrecan) also exhibited tissue region (lateral)-specific differences in structure between aged and young samples, suggesting that some ageing mechanisms may act locally within tissues. This study not only reveals possible age-associated differences in ECM protein structures which are tissue-region specific, but also highlights the ability of PLF as a proteomic tool to aid in biomarker discovery.

Multiparametric MR Investigation of Proteoglycan Diffusivity, T2 Relaxation, and Concentration in an Ex Vivo Model of Intervertebral Disc Degeneration.

BACKGROUND: Proteoglycan (PG) is a major component of the intervertebral disc extracellular matrix (ECM) that acts to hydrate the disc nucleus. Early detection of PG degradation is valuable for both diagnosis and preclinical research of intervertebral disc degeneration (IVDD). PURPOSE: To compare different MR techniques for detecting early degradative changes of PG in IVDD. STUDY TYPE: Prospective. PHANTOM/SPECIMEN: Glycosaminoglycan (GAG) phantom/bovine discs with papain injection and human cadaveric discs. FIELD STRENGTH/SEQUENCES: 7T/diffusion-weighted MR spectroscopy (DW-MRS), T2 -weighted MRS (T2 W-MRS), and chemical exchange saturation transfer (CEST) imaging. ASSESSMENT: DW-MRS, T2 W-MRS, and CEST imaging were applied longitudinally to measure PG diffusivity, T2 value, overall content, and spatial distribution in the disc nucleus with enzyme-induced proteolytic ECM degradation (n = 8). Similar MR measurements were applied in GAG phantom and human cadaveric discs with different levels of degeneration (n = 6). STATISTICAL TESTS: T-tests were conducted to measure the differences of PG properties between pre- and post-enzyme injection. Linear regression and mixed-effects models were used to assess the associations among different PG properties as well as the degeneration grades in human cadaveric discs. RESULTS: In bovine discs, PG diffusivity increased most rapidly after the enzyme was injected into the disc nucleus (12 hours postinjection, t = 5.76, P = 0.0007). The PG T2 value did not change significantly (t < 1.54, P > 0.17 for all timepoints) during ECM degradation and was not associated with PG diffusivity (t = 0.06, P = 0.95). PG distribution change was more rapid than overall PG content and was strongly associated with PG diffusivity increase (t = -9.25, P < 1 × 10-8 ). In severely degenerated human cadaveric discs, the PG ADCs and T2 values were both associated with degeneration grades. DATA CONCLUSION: PG diffusivity is a direct biomarker for early ECM degradation, while PG distribution can be an indirect biomarker for early IVDD. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020;51:1390-1400.

The Impact of Brain Metastases and Associated Neurocognitive Aspects on Health Utility Scores in EGFR Mutated and ALK Rearranged NSCLC: A Real World Evidence Analysis.

BACKGROUND: In lung cancer, brain metastases (BM) and their treatment are associated with high economic burden and inferior health-related quality of life. In the era of targeted therapy, real world evidence through health utility scores (HUS) is critical for economic analyses. MATERIALS AND METHODS: In a prospective observational cohort study (2014-2016), outpatients with stage IV lung cancer completed demographic and EQ-5D-3L surveys (to derive HUS). Health states and clinicopathologic variables were obtained from chart abstraction. Patients were categorized by the presence or absence of BM; regression analyses identified factors that were associated with HUS. A subset of patients prospectively completed neurocognitive function (NCF) tests and/or the FACT-brain (FACT-Br) questionnaire, which were then correlated with HUS (Spearman coefficients; regression analyses). RESULTS: Of 519 patients with 1,686 EQ-5D-3L-derived HUS, 94 (18%) completed NCF tests and 107 (21%) completed FACT-Br; 301 (58%) never developed BM, 24 (5%) developed first BM during study period, and 194 (37%) had BM at study entry. The sample was enriched (46%) for EGFR mutations (EGFRm) and ALK-rearrangements (ALKr). There were no HUS differences by BM status overall and in subsets by demographics. In multivariable analyses, superior HUS was associated with having EGFRm/ALKr (p < .0001), no prior radiation for extracranial disease (p < .001), and both intracranial (p = .002) and extracranial disease control (p < .01). HUS correlated with multiple elements of the FACT-Br and tests of NCF. CONCLUSION: Having BM in lung cancer is not associated with inferior HUS in a population enriched for EGFRm and ALKr. Patients exhibiting disease control and those with oncogene-addicted tumors have superior HUS. IMPLICATIONS FOR PRACTICE: In the setting of EGFR mutations or ALK rearrangement non-small cell lung cancer (NSCLC), a diagnosis of brain metastases no longer consigns the patient to an inferior health state suggesting that new economic analyses in NSCLC are needed in the era of targeted therapies. Additionally, the EQ-5D questionnaire is associated with measures of health-related quality of life and neurocognitive scores suggesting this tool should be further explored in prospective clinical studies.

Differential secretion pathways of proteins fused to the Escherichia coli maltose binding protein (MBP) in Pichia pastoris.

The Escherichia coli maltose binding protein (MBP) is an N-terminal fusion partner that was shown to enhance the secretion of some heterologous proteins from the yeast Pichia pastoris, a popular host for recombinant protein expression. The amount of increase in secretion was dependent on the identity of the cargo protein, and the fusions were proteolyzed prior to secretion, limiting its use as a purification tag. In order to overcome these obstacles, we used the MBP as C-terminal partner for several cargo peptides. While the Cargo-MBP proteins were no longer proteolyzed in between these two moieties when the MBP was in this relative position, the secretion efficiency of several fusions was lower than when MBP was located at the opposite end of the cargo protein (MBP-Cargo). Furthermore, fluorescence analysis suggested that the MBP-EGFP and EGFP-MBP proteins followed different routes within the cell. The effect of several Pichia pastoris beta-galactosidase supersecretion (bgs) strains, mutants showing enhanced secretion of select reporters, was also investigated on both MBP-EGFP and EGFP-MBP. While the secretion efficiency, proteolysis and localization of the MBP-EGFP was influenced by the modified function of Bgs13, EGFP-MBP behavior was not affected in the bgs strain. Taken together, these results indicate that the location of the MBP in a fusion affects the pathway and trans-acting factors regulating secretion in P. pastoris.

Empirically evaluating the WHO global code of practice on the international recruitment of health personnel's impact on four high-income countries four years after adoption.

BACKGROUND: Shortages of health workers in low-income countries are exacerbated by the international migration of health workers to more affluent countries. This problem is compounded by the active recruitment of health workers by destination countries, particularly Australia, Canada, UK and USA. The World Health Organization (WHO) adopted a voluntary Code of Practice in May 2010 to mitigate tensions between health workers' right to migrate and the shortage of health workers in source countries. The first empirical impact evaluation of this Code was conducted 11-months after its adoption and demonstrated a lack of impact on health workforce recruitment policy and practice in the short-term. This second empirical impact evaluation was conducted 4-years post-adoption using the same methodology to determine whether there have been any changes in the perceived utility, applicability, and implementation of the Code in the medium-term. METHODS: Forty-four respondents representing government, civil society and the private sector from Australia, Canada, UK and USA completed an email-based survey evaluating their awareness of the Code, perceived impact, changes to policy or recruitment practices resulting from the Code, and the effectiveness of non-binding Codes generally. The same survey instrument from the original study was used to facilitate direct comparability of responses. Key lessons were identified through thematic analysis. RESULTS: The main findings between the initial impact evaluation and the current one are unchanged. Both sets of key informants reported no significant policy or regulatory changes to health worker recruitment in their countries as a direct result of the Code due to its lack of incentives, institutional mechanisms and interest mobilizers. Participants emphasized the existence of previous bilateral and regional Codes, the WHO Code's non-binding nature, and the primacy of competing domestic healthcare priorities in explaining this perceived lack of impact. CONCLUSIONS: The Code has probably still not produced the tangible improvements in health worker flows it aspired to achieve. Several actions, including a focus on developing bilateral codes, linking the Code to topical global priorities, and reframing the Code's purpose to emphasize health system sustainability, are proposed to improve the Code's uptake and impact.

Mesenchymal stem cells reduce intervertebral disc fibrosis and facilitate repair.

Intervertebral disc degeneration is associated with back pain and radiculopathy which, being a leading cause of disability, seriously affects the quality of life and presents a hefty burden to society. There is no effective intervention for the disease and the etiology remains unclear. Here, we show that disc degeneration exhibits features of fibrosis in humans and confirmed this in a puncture-induced disc degeneration (PDD) model in rabbit. Implantation of bone marrow-derived mesenchymal stem cells (MSCs) to PDD discs can inhibit fibrosis in the nucleus pulposus with effective preservation of mechanical properties and overall spinal function. We showed that the presence of MSCs can suppress abnormal deposition of collagen I in the nucleus pulposus, modulating profibrotic mediators MMP12 and HSP47, thus reducing collagen aggregation and maintaining proper fibrillar properties and function. As collagen fibrils can regulate progenitor cell activities, our finding provides new insight to the limited self-repair capability of the intervertebral disc and importantly the mechanism by which MSCs may potentiate tissue regeneration through regulating collagen fibrillogenesis in the context of fibrotic diseases.

Coming together is a beginning: the making of an intervertebral disc.

The intervertebral disc (IVD) is a complex fibrocartilaginous structure located between the vertebral bodies that allows for movement and acts as a shock absorber in our spine for daily activities. It is composed of three components: the nucleus pulposus (NP), annulus fibrosus, and cartilaginous endplate. The characteristics of these cells are different, as they produce specific extracellular matrix (ECM) for tissue function and the niche in supporting the differentiation status of the cells in the IVD. Furthermore, cell heterogeneities exist in each compartment. The cells and the supporting ECM change as we age, leading to degenerative outcomes that often lead to pathological symptoms such as back pain and sciatica. There are speculations as to the potential of cell therapy or the use of tissue engineering as treatments. However, the nature of the cells present in the IVD that support tissue function is not clear. This review looks at the origin of cells in the making of an IVD, from the earliest stages of embryogenesis in the formation of the notochord, and its role as a signaling center, guiding the formation of spine, and in its journey to become the NP at the center of the IVD. While our current understanding of the molecular signatures of IVD cells is still limited, the field is moving fast and the potential is enormous as we begin to understand the progenitor and differentiated cells present, their molecular signatures, and signals that we could harness in directing the appropriate in vitro and in vivo cellular responses in our quest to regain or maintain a healthy IVD as we age.

System dynamic modeling on construction waste management in Shenzhen, China.

This article examines the complexity of construction waste management in Shenzhen, Mainland China. In-depth analysis of waste generation, transportation, recycling, landfill and illegal dumping of various inherent management phases is explored. A system dynamics modeling using Stella model is developed. Effects of landfill charges and also penalties from illegal dumping are also simulated. The results show that the implementation of comprehensive policy on both landfill charges and illegal dumping can effectively control the illegal dumping behavior, and achieve comprehensive construction waste minimization. This article provides important recommendations for effective policy implementation and explores new perspectives for Shenzhen policy makers.

In vitro and in vivo models define a molecular signature reference for human embryonic notochordal cells.

Understanding the emergence of human notochordal cells (NC) is essential for the development of regenerative approaches. We present a comprehensive investigation into the specification and generation of bona fide NC using a straightforward pluripotent stem cell (PSC)-based system benchmarked with human fetal notochord. By integrating in vitro and in vivo transcriptomic data at single-cell resolution, we establish an extended molecular signature and overcome the limitations associated with studying human notochordal lineage at early developmental stages. We show that TGF-ß inhibition enhances the yield and homogeneity of notochordal lineage commitment in vitro. Furthermore, this study characterizes regulators of cell-fate decision and matrisome enriched in the notochordal niche. Importantly, we identify specific cell-surface markers opening avenues for differentiation refinement, NC purification, and functional studies. Altogether, this study provides a human notochord transcriptomic reference that will serve as a resource for notochord identification in human systems, diseased-tissues modeling, and facilitating future biomedical research.

What is the "DNA" of healthy buildings? A critical review and future directions.

Since the outbreak of COVID-19, buildings that provide improved performance have aroused extensive discussion. Nowadays, the connotation of healthy building is becoming complex, performance metrics for healthy buildings vary significantly from different regions in the world and there may be information asymmetry among stakeholders. Consequently, building health performance cannot be effectively achieved. However, previous studies have launched extensive reviews on green building, and there remains a lack of comprehensive and systematic reviews on healthy buildings. To address the above issues, therefore, this research aims to (1) conduct a thorough review of healthy building research and reveal its nature; and (2) identify the current research gaps and propose possible future research directions. Content analysis using NVivo were applied to review 238 relevant publications. A DNA framework of healthy buildings, which clarifies the characteristics, triggers, guides and actions, was then constructed for better understanding of the nature of them. Subsequently, the application of DNA framework and the directions of future research were discussed. Six future research directions were finally recommended, including life-cycle thinking, standard systems improvement, policies & regulations, awareness increase, healthy building examination, and multidisciplinary integration. This research differs from previous ones because it painted a panorama of previous healthy building research. Findings of this research contribute to reveal knowledge map of healthy buildings, guide researchers to fill existing knowledge gaps, provide a standardized platform for healthy building stakeholders, and promote high-quality development of healthy buildings.

Digital inspection techniques of modular integrated construction.

As a new construction form, modular integrated construction (MiC) can effectively improve the construction quality and productivity, especially for the construction of high-density and high-rise buildings. However, the current MiC quality inspection relies on manual inspection, which is inefficient and unreliable. Systematic research on digital inspection techniques (DITs) is fragmented and unable to fully realize the potential of the MiC industry. This study aims to explore the current state of DIT applications in MiC and to summarize the knowledge in the field through an analysis of 248 relevant literatures. Accordingly, this study combines bibliometric analysis, and a system engineering evaluation approach based on 3D structures (time, knowledge, and logic) to provide an overview of the current state of DIT development. The overview includes the application of DITs from a whole life cycle perspective, the DIT knowledge structure, specific DIT applications, as well as current challenges and future prospects.

Extensible carbon emission factor database: empirical study for the Chinese construction industry.

A carbon emission factor (CEF) database is required for the basis of carbon emission calculation in construction projects. However, the default values for existing CEF databases cannot cover the complex resources involved in a construction project. Therefore, this paper proposes a three-step method to guide the establishment of an extensible CEF database for the construction industry, including (1) data collection and parser, (2) data extension, and (3) data encoding and storage. The data extension mechanisms provide the supply chain perspective considering temporal issues and the accounting perspective to streamline the process. Aiming to address the lack of a comprehensive CEF database for the construction industry in China, this paper uses this method to establish a carbon emission factor database for the Chinese construction industry (CEFD for CCI). This database is open and free with 646 CEFs, including five parts: energy, human, material, machinery, and greenspace. This paper provides a way for developing and less developed countries to establish an expandable CEF database, which benefits the parser, extension, encoding, and storage of new resources, as well as computer access.

Recommendations for intervertebral disc notochordal cell investigation: From isolation to characterization.

Background: Lineage-tracing experiments have established that the central region of the mature intervertebral disc, the nucleus pulposus (NP), develops from the embryonic structure called "the notochord". However, changes in the cells derived from the notochord which form the NP (i.e., notochordal cells [NCs]), in terms of their phenotype and functional identity from early developmental stages to skeletal maturation are less understood. These key issues require further investigation to better comprehend the role of NCs in homeostasis and degeneration as well as their potential for regeneration. Progress in utilizing NCs is currently hampered due to poor consistency and lack of consensus methodology for in vitro NC extraction, manipulation, and characterization. Methods: Here, an international group has come together to provide key recommendations and methodologies for NC isolation within key species, numeration, in vitro manipulation and culture, and characterization. Results: Recommeded protocols are provided for isolation and culture of NCs. Experimental testing provided recommended methodology for numeration of NCs. The issues of cryopreservation are demonstrated, and a pannel of immunohistochemical markers are provided to inform NC characterization. Conclusions: Together we hope this article provides a road map for in vitro studies of NCs to support advances in research into NC physiology and their potential in regenerative therapies.

The effect of vitamin D supplementation on serum levels of fibroblast growth factor- 23: A systematic review and meta-analysis of randomized controlled trials.

Previous studies of the effect of vtamin D on serum levels of fibroblast growth factor- 23 (FGF-23) have yeilded an inconsistent findings. This systematic review and meta-analysis of randomized controlled trials (RCTs) sought to investigate the effect of vitamin D supplementation on serum levels of FGF-23. PubMed, Scopus, ISI Web of Science, and the Cochrane Library were searched, from database inception to November 2020, for RCTs that evaluated the effects of native or active vitamin D supplementation on serum levels of FGF-23 in adults. Weighted mean difference (WMD) were calculated and random effects meta-analysis was used to estimate the overall effects. Twenty-seven trials were included in the meta-analysis. Supplementation with native vitamin D (23 studies, n = 2247 participants; weighted mean difference [WMD] = 0.5 pg/mL, 95 % CI: -0.52 to 1.51, P = 0.33; I2 = 29.9 %), and active vitamin D (5 studies, n = 342 participants, WMD = 29.45 pg/mL, 95 % CI: -3.9 to 62.81, P = 0.08; I2 = 99.3%) had no significant effects on serum FGF-23 concentration. In subgroup analyses, supplementation with ergocalciferol (3 studies, n = 205 participants; WMD = 18.27 pg/mL, 95 % CI: 5.36-31.17, P = 0.006), and daily dosing regimens (9 studies, n = 1374 participants; WMD = 0.41 pg/mL, 95 % CI: 0.22 to 0.59, P < 0.001) increased serum FGF-23 levels compared to control. Overall, our findings revealed no significan effect of vitamin D supplementation on serum FGF-23 concentration. However, further high quality, large-scale studies are needed to better elucidate this relationship.

Peptide location fingerprinting identifies species- and tissue-conserved structural remodelling of proteins as a consequence of ageing and disease.

Extracellular matrices (ECMs) in the intervertebral disc (IVD), lung and artery are thought to undergo age-dependant accumulation of damage by chronic exposure to mechanisms such as reactive oxygen species, proteases and glycation. It is unknown whether this damage accumulation is species-dependant (via differing lifespans and hence cumulative exposures) or whether it can influence the progression of age-related diseases such as atherosclerosis. Peptide location fingerprinting (PLF) is a new proteomic analysis method, capable of the non-targeted identification of structure-associated changes within proteins. Here we applied PLF to publicly available ageing human IVD (outer annulus fibrosus), ageing mouse lung and human arterial atherosclerosis datasets and bioinformatically identified novel target proteins alongside common age-associated differences within protein structures which were conserved between three ECM-rich organs, two species, three IVD tissue regions, sexes and in an age-related disease. We identify peptide yield differences across protein structures which coincide with biological regions, potentially reflecting the functional consequences of ageing or atherosclerosis for macromolecular assemblies (collagen VI), enzyme/inhibitor activity (alpha-2 macroglobulin), activation states (complement C3) and interaction states (laminins, perlecan, fibronectin, filamin-A, collagen XIV and apolipoprotein-B). Furthermore, we show that alpha-2 macroglobulin and collagen XIV exhibit possible shared structural consequences in IVD ageing and arterial atherosclerosis, providing novel links between an age-related disease and intrinsic ageing. Crucially, we also demonstrate that fibronectin, laminin beta chains and filamin-A all exhibit conserved age-associated structural differences between mouse lung and human IVD, providing evidence that ECM, and their associating proteins, may be subjected to potentially similar mechanisms or consequences of ageing across both species, irrespective of differences in lifespan and tissue function.

Physical Activity and the Home Environment of Pre-School-Aged Children in Urban Bangladesh.

Physical activity (PA) is a key determinant of health and development, yet few studies have examined PA levels and risk factors for low PA among young children in low- and middle-income countries. This study aimed to describe the PA and sedentary (SED) behavior levels of preschool-aged children in Dhaka, Bangladesh, and to estimate the associations between potential risk factors in the home built environment and moderate to vigorous PA (MVPA). In a sample of preschool-aged children (n = 65) in Dhaka, PA and SED behavior were measured for 7 days using ActiGraph GT3X-BT accelerometers. Characteristics of the home built environment, socioeconomic factors, and anthropometry were also measured. Linear mixed-effects models were used to estimate multivariable-adjusted associations between characteristics of the home environment and MVPA. Preschool-aged children spent a mean (±standard deviation) 421 ± 48 and 82 ± 23 min per day sedentary and in MVPA, respectively. There were no statistically significant associations between factors in the home built environment (indoor area, presence of an open stairwell, and presence of gross motor activity facilitating items) and MVPA. These findings suggest that the studied characteristics of the home built environment may not significantly influence the MVPA observed among preschool-aged children in Dhaka. Future research should focus on other structural and behavioral factors that facilitate PA among young children in dense urban settings.

PRIMUS: Comprehensive proteomics of mouse intervertebral discs that inform novel biology and relevance to human disease modelling.

Mice are commonly used to study intervertebral disc (IVD) biology and related diseases such as IVD degeneration. Discs from both the lumbar and tail regions are used. However, little is known about compartmental characteristics in the different regions, nor their relevance to the human setting, where a functional IVD unit depends on a homeostatic proteome. Here, we address these major gaps through comprehensive proteomic profiling and in-depth analyses of 8-week-old healthy murine discs, followed by comparisons with human. Leveraging on a dataset of over 2,700 proteins from 31 proteomic profiles, we identified key molecular and cellular differences between disc compartments and spine levels, but not gender. The nucleus pulposus (NP) and annulus fibrosus (AF) compartments differ the most, both in matrisome and cellularity contents. Differences in the matrisome are consistent with the fibrous nature required for tensile strength in the AF and hydration property in the NP. Novel findings for the NP cells included an enrichment in cell junction proteins for cell-cell communication (Cdh2, Dsp and Gja1) and osmoregulation (Slc12a2 and Wnk1). In NP cells, we detected heterogeneity of vacuolar organelles; where about half have potential lysosomal function (Vamp3, Copb2, Lamp1/2, Lamtor1), some contain lipid droplets and others with undefined contents. The AF is enriched in proteins for the oxidative stress responses (Sod3 and Clu). Interestingly, mitochondrial proteins are elevated in the lumbar than tail IVDs that may reflect differences in metabolic requirement. Relative to the human, cellular and structural information are conserved for the AF. Even though the NP is more divergent between mouse and human, there are similarities at the level of cell biology. Further, common cross-species markers were identified for both NP (KRT8/19, CD109) and AF (COL12A1). Overall, mouse is a relevant model to study IVD biology, and an understanding of the limitation will facilitate research planning and data interpretation, maximizing the translation of research findings to human IVDs.