Components Of Matrices Research Articles

#5649 HEPARANASE OVEREXPRESSION MODIFIES PODOCYTE MOTILITY

Abstract Background and Aims Heparanase is an endo-β-d-glucuronidase that degrades heparan sulfate side chains, which are essential components of extracellular matrices and cell surfaces, including in the kidney filtration apparatus, the glomerulus. Upregulation of heparanase in glomerular diseases (GDs) was demonstrated in experimental models of GDs and in humans. Using transgenic mice overexpressing the human heparanase gene, we recently showed that heparanase reduced proteinuria and preserved the glomerular filtration barrier (GFB) after Adriamycin-induced injury. Furthermore, heparanase improved survival of key GFB cells, the podocytes and enhanced their autophagic flux both in vitro and in vivo. Here, we aimed to study the potential role of heparanase on podocyte locomotion and adhesion. Methods We utilized immortalized human podocyte cell line AB8/13 (a kind gift of Prof. Moin Saleem, Bristol, UK) as an experimental platform. Cells were infected with pLenti6/V5-DEST carrying the heparanase gene construct (H) or control empty vector (V) and were allowed to differentiate for 14 days. To induce injury, differentiated podocytes were treated with Adriamycin (0.5 μg/mL), mimicking Adriamycin nephropathy, an established experimental model for progressive proteinuric GDs. For readouts, we used scratch assay, RT-qPCR, Western blot (WB) and immunofluorescence (IF) analyses. Results The in vitro scratch assay showed that differentiated (H) podocytes migrated at a slower rate compared with control (V) podocytes, both at baseline and after a 12-hour treatment with Adriamycin. Hence, we hypothesized that heparanase may alter podocyte adhesion properties. Indeed, IF staining of differentiated (H) podocytes exhibited an increase in focal contacts containing vinculin compared with control (V) cells treated with Adriamycin. Of note, we observed no differences in vinculin abundance by WB, suggesting that heparanase mediates the active form of vinculin. Moreover, among the integrins, we noticed temporal upregulation of ITGB1 transcription, as early as two hours after Adriamycin treatment, in (H) compared with control (V) podocytes (P = 0.032). Conclusions Collectively, our results suggest that in response to Adriamycin injury, constitutive heparanase overexpression could stabilize podocyte focal adhesions and control motility. Although further research is needed, improving the anchoring of podocytes over the basement membrane may provide an additional cellular mechanism by which heparanase conferred protection against Adriamycin toxicity.

Comparison of optical feedback cavity enhanced absorption spectroscopy and gas chromatography for the measurement of the main components and impurities in biogas, landfill gas, biomethane and carbon dioxide streams

In this study, we evaluated the performances of a custom-built optical feedback cavity enhanced absorption spectroscopy (OFCEAS) instrument for the determination of the composition of energy gases, focusing on methane and carbon dioxide as main components, and carbon monoxide as impurities, in comparison with the well-established, validated, and traceable gas chromatographic method. A total of 115 real sample gases collected in biogas plants or landfills were analyzed using with both techniques over a period of 12 months. The comparison of the techniques showed that the virtual model which allows the measurement, needs to be optimized using real samples of varied compositions. The OFCEAS measurement technique was found to be capable of measuring both the main components and a trace component in different matrices; to within a 2% measurement uncertainty (higher than the gas chromatograph/thermal conductivity detector (GC/TCD) method). The OFCEAS method exhibits a very fast response, does not require daily calibration, and can be implemented online. The agreements between the OFCEAS technique and the GC/TCD method show that the drift of the OFCEAS instruments remains acceptable in the long term as long as no change is made to the virtual model. Matrix effects were observed, and those need to be taken into consideration when analyzing different types of samples.

Homozygous splice variant (c.1741-6G>A) of the COL6A1 gene in three patients with Ullrich congenital muscular dystrophy

The three major collagen VI genes: COL6A1, COL6A2, and COL6A3 encode microfibrillar components of extracellular matrices in multiple tissues including muscles and tendons. Pathogenic variants in the collagen VI genes cause collagen VI-related dystrophies representing a continuum of conditions from Bethlem myopathy at the milder end to Ullrich congenital muscular dystrophy at the more severe end. Here we describe a pathogenic variant in the COL6A1 gene (NM_001848.3; c.1741-6G>A) found in homozygosity in three patients with Ullrich congenital muscular dystrophy. The patients suffered from severe muscle impairment characterised by proximal weakness, distal hyperlaxity, joint contractures, wheelchair-dependency, and use of nocturnal non-invasive ventilation. The pathogenicity was verified by RNA analyses showing that the variant induced aberrant splicing leading to a frameshift and loss of function. The analyses were in line with immunocytochemistry studies of patient-derived skin fibroblasts and muscle tissue demonstrating impaired secretion of collagen VI into the extracellular matrix. Thereby, we add the variant c.1741-6G>A to the list of pathogenic, recessive, splice variants in COL6A1 causing Ullrich congenital muscular dystrophy. The variant is listed in ClinVar as of “uncertain significance” and “likely benign” and may presumably have been overlooked in other patients.

Fasciola hepatica juveniles interact with the host fibrinolytic system as a potential early-stage invasion mechanism.

The trematode Fasciola hepatica is the most widespread causative agent of fasciolosis, a parasitic disease that mainly affects humans and ruminants worldwide. During F. hepatica infection, newly excysted juveniles (FhNEJ) emerge in the duodenum of the mammalian host and migrate towards their definitive location, the intra-hepatic biliary ducts. Understanding how F. hepatica traverses the intestinal wall and migrates towards the liver is pivotal for the development of more successful strategies against fasciolosis. The central enzyme of the mammalian fibrinolytic system is plasmin, a serine protease whose functions are exploited by a number of parasite species owing to its broad spectrum of substrates, including components of tissue extracellular matrices. The aim of the present work is to understand whether FhNEJ co-opt the functions of their host fibrinolytic system as a mechanism to facilitate trans-intestinal migration. A tegument-enriched antigenic extract of FhNEJ (FhNEJ-Teg) was obtained in vitro, and its capability to bind the zymogen plasminogen (PLG) and enhance its conversion to the active protease, plasmin, were analyzed by a combination of enzyme-linked immunosorbent, chromogenic and immunofluorescence assays. Additionally, PLG-binding proteins in FhNEJ-Teg were identified by bidimensional electrophoresis coupled to mass spectrometry analysis, and the interactions were validated using FhNEJ recombinant proteins. Our results show that FhNEJ-Teg contains proteins that bind PLG and stimulate its activation to plasmin, which could facilitate the traversal of the intestinal wall by FhNEJ and contribute to the successful establishment of the parasite within its mammalian host. Altogether, our findings contribute to a better understanding of host-parasite relationships during early fasciolosis and may be exploited from a pharmacological and/or immunological perspective for the development of treatment and control strategies against this global disease.

Model order reduction for parameterized electromagnetic problems using matrix decomposition and deep neural networks

A non-intrusive model order reduction (MOR) method for solving parameterized electromagnetic scattering problems is proposed in this paper. A database collecting snapshots of high-fidelity solutions is built by solving the parameterized time-domain Maxwell equations for some values of the material parameters using a fullwave solver based on a high order discontinuous Galerkin time-domain (DGTD) method. To perform a prior dimensionality reduction, a set of reduced basis (RB) functions are extracted from the database via a two-step proper orthogonal decomposition (POD) method. Intrinsic coordinates of the high-fidelity solutions are further compressed through a convolutional autoencoder (CAE) network. Singular value decomposition (SVD) is then used to extract the principal components of the low dimensional coding matrices generated by CAE, and a cubic spline interpolation-based (CSI) approach is employed for approximating the dominating time- and parameter-modes of these matrices. The generation of the reduced basis and the training of the CAE and CSI are accomplished in the offline stage, thus the RB solution for given time/parameter values can be quickly recovered via outputs of the interpolation model and decoder network. In particular, the offline and online stages of the proposed RB method are completely decoupled, which ensures the validity of the method. The performance of the proposed CAE-CSI ROM is illustrated with numerical experiments for scattering of a plane wave by a 2-D dielectric disk and a multi-layer heterogeneous medium.

Discussion of “Multivariate dynamic modeling for Bayesian forecasting of business revenue”

Discussion of “Multivariate dynamic modeling for Bayesian forecasting of business revenue”

Nanocomposite Hydrogels as Functional Extracellular Matrices

Over recent years, nano-engineered materials have become an important component of artificial extracellular matrices. On one hand, these materials enable static enhancement of the bulk properties of cell scaffolds, for instance, they can alter mechanical properties or electrical conductivity, in order to better mimic the in vivo cell environment. Yet, many nanomaterials also exhibit dynamic, remotely tunable optical, electrical, magnetic, or acoustic properties, and therefore, can be used to non-invasively deliver localized, dynamic stimuli to cells cultured in artificial ECMs in three dimensions. Vice versa, the same, functional nanomaterials, can also report changing environmental conditions-whether or not, as a result of a dynamically applied stimulus-and as such provide means for wireless, long-term monitoring of the cell status inside the culture. In this review article, we present an overview of the technological advances regarding the incorporation of functional nanomaterials in artificial extracellular matrices, highlighting both passive and dynamically tunable nano-engineered components.

Inhibitory machinery for the functional dystroglycan glycosylation.

Dystroglycan (DG), a muscular transmembrane protein, plays a critical role in transducing extracellular matrix-derived signals to the cytoskeleton and provides physical strength to skeletal muscle cell membranes. The extracellular domain of DG, α-DG, displays unique glycosylation patterns. Fully functional glycosylation is required for this domain to interact with components of extracellular matrices, including laminin. One of the unique sugar compositions found in such functional glycans on DG is two ribitol phosphates that are transferred by the sequential actions of fukutin (FKTN) and fukutin-related protein (FKRP), which use CDP-ribitol as a donor substrate. These are then further primed for matriglycan biosynthesis. A recent in vitro study reported that glycerol phosphate could be similarly added to α-DG by FKTN and FKRP if they used CDP-glycerol (CDP-Gro) as a donor substrate. However, the physiological relevance of these findings remains elusive. Imae et al. addressed the knowledge gap regarding whether CDP-Gro is present in mammals and how CDP-Gro is synthesized and functions in mammals.

Consistency-Induced Multiview Subspace Clustering.

Multiview clustering has received great attention and numerous subspace clustering algorithms for multiview data have been presented. However, most of these algorithms do not effectively handle high-dimensional data and fail to exploit consistency for the number of the connected components in similarity matrices for different views. In this article, we propose a novel consistency-induced multiview subspace clustering (CiMSC) to tackle these issues, which is mainly composed of structural consistency (SC) and sample assignment consistency (SAC). To be specific, SC aims to learn a similarity matrix for each single view wherein the number of connected components equals to the cluster number of the dataset. SAC aims to minimize the discrepancy for the number of connected components in similarity matrices from different views based on the SAC assumption, that is, different views should produce the same number of connected components in similarity matrices. CiMSC also formulates cluster indicator matrices for different views, and shared similarity matrices simultaneously in an optimization framework. Since each column of similarity matrix can be used as a new representation of the data point, CiMSC can learn an effective subspace representation for the high-dimensional data, which is encoded into the latent representation by reconstruction in a nonlinear manner. We employ an alternating optimization scheme to solve the optimization problem. Experiments validate the advantage of CiMSC over 12 state-of-the-art multiview clustering approaches, for example, the accuracy of CiMSC is 98.06% on the BBCSport dataset.

A dynamic interplay between chitin synthase and the proteins Expansion/Rebuf reveals that chitin polymerisation and translocation are uncoupled in Drosophila

Chitin is a highly abundant polymer in nature and a principal component of apical extracellular matrices in insects. In addition, chitin has proved to be an excellent biomaterial with multiple applications. In spite of its importance, the molecular mechanisms of chitin biosynthesis and chitin structural diversity are not fully elucidated yet. To investigate these issues, we use Drosophila as a model. We previously showed that chitin deposition in ectodermal tissues requires the concomitant activities of the chitin synthase enzyme Kkv and the functionally interchangeable proteins Exp and Reb. Exp/Reb are conserved proteins, but their mechanism of activity during chitin deposition has not been elucidated yet. Here, we carry out a cellular and molecular analysis of chitin deposition, and we show that chitin polymerisation and chitin translocation to the extracellular space are uncoupled. We find that Kkv activity in chitin translocation, but not in polymerisation, requires the activity of Exp/Reb, and in particular of its conserved Nα-MH2 domain. The activity of Kkv in chitin polymerisation and translocation correlate with Kkv subcellular localisation, and in absence of Kkv-mediated extracellular chitin deposition, chitin accumulates intracellularly as membrane-less punctae. Unexpectedly, we find that although Kkv and Exp/Reb display largely complementary patterns at the apical domain, Exp/Reb activity nonetheless regulates the topological distribution of Kkv at the apical membrane. We propose a model in which Exp/Reb regulate the organisation of Kkv complexes at the apical membrane, which, in turn, regulates the function of Kkv in extracellular chitin translocation.

Determination of ethanol in hand sanitizers by a self-built headspace device and gas chromatography

Introduction: Headspace sampling coupled with gas chromatography (HS-GC) has been proven to be a very useful technique for the determination of volatile and semivolatile components in complex matrices by avoiding tedious sample preparation. In this study, the HS system was fabricated at low cost, exploiting unused GC sensor-heaters. Methods: The accuracy and stability of the self-built HS were evaluated, and the HS-GC-FID system was applied to the determination of ethanol in hand sanitizer gels. The HS operating conditions, including temperature and equilibrium time, were optimized using a central composite face-centered design (CCFC) and MODDE 5.0 software. Samples incubated at 80 °C for 25 min gave the best results with respect to sensitivity and reproducibility (RSD < 3%). Results: The calibration curve showed high linearity (R2 > 0.998) in the range of 0.25 to 2.5% (w/w) ethanol, using acetonitrile 1% (w/w) as an internal standard. The recovery ranged between 104.1 and 108.3% using spiked samples on real matrices. A small survey of 11 commercially available samples collected in the local markets showed that only one of them did not meet the standards set by the FDA.

Machine Learning-Assisted Synchronous Fluorescence Sensing Approach for Rapid and Simultaneous Quantification of Thiabendazole and Fuberidazole in Red Wine.

Rapid analysis of components in complex matrices has always been a major challenge in constructing sensing methods, especially concerning time and cost. The detection of pesticide residues is an important task in food safety monitoring, which needs efficient methods. Here, we constructed a machine learning-assisted synchronous fluorescence sensing approach for the rapid and simultaneous quantitative detection of two important benzimidazole pesticides, thiabendazole (TBZ) and fuberidazole (FBZ), in red wine. First, fluorescence spectra data were collected using a second derivative constant-energy synchronous fluorescence sensor. Next, we established a prediction model through the machine learning approach. With this approach, the recovery rate of TBZ and FBZ detection of pesticide residues in red wine was 101% ± 5% and 101% ± 15%, respectively, without resorting complicated pretreatment procedures. This work provides a new way for the combination of machine learning and fluorescence techniques to solve the complexity in multi-component analysis in practical applications.

How to evaluate neoclassical transport coefficients by a single δf simulation

The δf method is extended to calculate all possible components of neoclassical transport matrices, including non-diagonal components and interspecies components of any species combinations in an arbitrary magnetic field configuration, by a single simulation. The method is implemented in a global neoclassical code FORTEC-3D and applied to cases of multi-ion species plasmas in a tokamak and a helical configuration, respectively. The results are benchmarked against analytic solutions and local simulation results. It is found that the results obtained with the newly developed method provide reliable solutions that satisfy the Onsager symmetry relation as well as the intrinsic ambipolarity in a tokamak configuration.

Effects of Elastic Couplings in a Compressed Plate Element with Cut-Out.

Analytical calculations were performed on carbon fiber-reinforced polymer (CFRP) laminates in an asymmetrical configuration. The asymmetric configuration of composites was investigated, where extension-twisting and extension-bending couplings were used to obtain the elastic element. Analysis of the presence of elastic couplings was conducted according to Classical Laminate Theory (CLT). Components of matrices A, B, and D, as well as the parameters Dc and Bt, were obtained using the MATLAB software environment. The results show that couplings between the extension and bending, as well as between the extension and twisting, were strongly dependent on specimen plies' orientation. Moreover, additional analysis was performed on the influence of layer angle on the terms which are components of the Bt and Dc coefficients. The results indicate that the angle of laying fibers around 45-50° significantly amplifies the effects of elastic couplings.

Proteoglycans Determine the Dynamic Landscape of EMT and Cancer Cell Stemness.

Proteoglycans (PGs) are pivotal components of extracellular matrices, involved in a variety of processes such as migration, invasion, morphogenesis, differentiation, drug resistance, and epithelial-to-mesenchymal transition (EMT). Cellular plasticity is a crucial intermediate phenotypic state acquired by cancer cells, which can modulate EMT and the generation of cancer stem cells (CSCs). PGs affect cell plasticity, stemness, and EMT, altering the cellular shape and functions. PGs control these functions, either by direct activation of signaling cascades, acting as co-receptors, or through regulation of the availability of biological compounds such as growth factors and cytokines. Differential expression of microRNAs is also associated with the expression of PGs and their interplay is implicated in the fine tuning of cancer cell phenotype and potential. This review summarizes the involvement of PGs in the regulation of EMT and stemness of cancer cells and highlights the molecular mechanisms.

Established methods and comparison of 10 organic acids based on reversed phase chromatography and hydrophilic interaction chromatography

ABSTRACT High performance liquid chromatography (HPLC) methods have been established for simultaneously determining the 10 organic acids in fruit or soil. Two liquid chromatographic (LC) columns with reversed phase (RP) (Titank C18) and hydrophilic interaction (HILIC) (Poroshell 120 HILIC-Z) were selected to separate organic acids in molecular or ionic state, respectively. Meanwhile, the mobile phases had different solvents and pH values in the two states. Results indicated that these two columns can complement each other and avoid various matrix interferences. The limits of detection (LOD) of organic acids (S/N ≥ 3) were 0.002–0.521 μg∙mL−1 in the molecular state and 0.003–0.459 μg∙mL−1 in the ionic state, and the corresponding limits of quantification (LOQ) (S/N ≥ 10) were 0.007–1.737 μg∙mL−1 and 0.009–1.530 μg∙mL−1. The above methods can provide a technical support for the analysis of organic acid components in other matrices.

Simultaneous quantification of multiple active components of the ginkgo ketoester tablet when combined with donepezil in four biological matrices from an Alzheimer’s animal model: Evaluation of drug distribution patterns in vivo

Ginkgo ketoester tablets (GT) and donepezil are clinically used in combination to treat Alzheimer’s disease (AD). This study aimed to investigate the anti-dementia effects of two drugs alone and in combination by monitoring the distribution patterns of their active components in different biological matrices. A practical analytical method was developed for simultaneously quantifying 38 active compounds in different matrices at trace levels using ultra-performance liquid chromatography coupled with triple-quadrupole linear ion-trap tandem mass spectrometry (UHPLC-MS2). Under optimized conditions, good chromatographic separation of the 38 target compounds was achieved within 14 min, with acceptable linearity, limits of detections and quantifications, precision, stability, and extraction recovery and matrix effects. The developed analytical method quantified the 38 active components in the brain, plasma, intestine, and intestinal contents of AD mice treated with GT alone, donepezil alone, and a combination of the two drugs. The result showed that the combination group had enhanced anti-dementia active compounds and reduced levels of toxic compounds entering the targeted tissues. These findings support the combined use of GT and donepezil for increasing anti-dementia treatment efficiency and reducing toxicity. The proposed UHPLC-MS2 strategy could be used to monitor the levels of active compounds from different biological matrices in future studies.

Research progress on bioaccessibility of persistent organic pollutants in oral exposure matrices

<p indent="0mm">Persistent organic pollutants (POPs) have been widely concerned due to their bioaccumulation, environmental persistence, and strong toxic effects on humans and organisms. Oral digestion via food, dust, and soil is the most important route for humans to uptake POPs. However, not all POPs that enter human body are bioavailable, thus exposure risk assessment based on the total amount of POPs in matrices would overestimate the resulting health risks. Measurement of bioaccessibility using <italic>in vitro</italic> gastrointestinal (GI) digestive simulation has been used to predict the bioavailability of POPs. In this paper, the impacts of <italic>in vitro</italic> experimental approaches, properties of oral matrices, compositions of digestive fluid, and properties of POPs on the bioaccessibility of POPs in oral exposure matrices are comprehensively reviewed and analyzed. The dynamic <italic>in vitro</italic> GI digestive simulation improved the accuracy of the results compared with traditional static GI digestive simulation. The digestion of nutrients in the GI tract and cooking methods affect the distribution of POPs between matrices and digestive fluids, thus affecting bioaccessibility. Lipids generally enhanced the bioaccessibility of most POPs because they promote the formation of stable fatty acid-bile salt micelles and increase the solubility of POPs in digestive fluid. However, this solubilization effect of mixed micelles does not apply to POPs with very high hydrophobicity because they prefer to distribute in the undigested food matrix. The bioaccessibility of POPs is mostly positively correlated with the carbohydrate content of food, whereas the effects of protein and dietary fiber were uncertain. Particle size and organic matter content of dust or soil are important factors affecting the bioaccessibility of POPs. The smaller the particle size of the dust or soil, the larger specific surface area, and the digestive fluid displayed strong capacity to dissolve POPs, thus increasing their bioaccessibility. Organic matter has a significant effect on the adsorption and desorption of POPs from dust or soil. The higher the organic matter content, the more POPs will be adsorbed, thus hindering the release of POPs from the matrices. Bile salts and various digestive enzymes such as pepsin and trypsin can also change the bioaccessibility of POPs by affecting the digestion process of matrices. There is generally a negative relationship between the bioaccessibility of POPs and their log<italic>K</italic>_OW values. The higher the hydrophobicity of POPs, the more difficult it is to dissolve in the digestive fluid. Different migration routes of POPs will also lead to different bioaccessibility, and the bioaccessibility of POPs adsorbed into the matrices is higher than that of POPs existing as a component of matrices. When considering bioaccessibility, the estimated daily intake of POPs from a matrix will decrease and the estimated exposure risk will therefore be reduced. Thus the contribution of POPs via different matrices to total human exposure should be re-examined. Collectively, bioaccessibility should be fully considered in the assessment of oral exposure and health risk to ensure accurate results. There are still some limitations in the current research. Firstly, results obtained using different <italic>in vitro</italic> methods varied widely and validation with <italic>in vivo</italic> data is lacking. Secondly, current studies mostly focused on only one oral matrix which cannot represent rich daily diets and different exposure scenarios among different populations. Thirdly, there is still a big gap in the research on the bioaccessibility of emerging POPs and the mixed exposure to multiple POPs. This paper provides an important theoretical basis for the accurate assessment of the human exposure risk of POPs, and for formulating measures to reduce the oral exposure risk of POPs in different populations.

Behavior of Glass-like and Mineral-like Phosphate Compounds with an Immobilized Chloride Mixture in Hydrogen Peroxide Solutions

A new type of high-level waste (HLW) is generated during pyrochemical reprocessing of mixed nitride spent uranium–plutonium nuclear fuel. Such waste is a spent electrolyte, which is a mixture of chloride salts containing approximately 25.7 wt.% LiCl + 31.6 wt.% KCl + 4.1 wt.% CsCl + 5.1 wt.% BaCl2 + 3.8 wt.% SrCl2 + 29.7 wt.% LaCl3, and its immobilization in reliable matrices is an actual radiochemical problem. The structure and hydrolytic stability of sodium aluminoironphosphate (NAFP) glass and a low-temperature mineral-like magnesium potassium phosphate (MPP) matrix, which are promising for spent electrolyte immobilization in the presence of hydrogen peroxide solutions simulating natural water radiolysis products, were studied in this work. The structure of the samples was studied using the SEM-EDS method. It was shown that the initial samples of NAFP glass after leaching in hydrogen peroxide solutions are prone to precipitation of crystalline phases on the surface, which are mainly represented by a mixture of sodium–iron–aluminum pyrophosphates. It was established that the leaching rate of structure-forming components of NAFP and MPP matrices generally increase, but remain at a low level, meeting modern requirements for HLW immobilization. This confirms the effectiveness of the studied matrices for the industrial use of the spent electrolyte.

Presolar O- and C-anomalous grains in unequilibrated ordinary chondrite matrices

Presolar grains are trace components in chondrite matrices. Their abundances and compositions have been systematically studied in carbonaceous chondrites but rarely in situ in other major chondrite classes. We have conducted a NanoSIMS isotopic search for presolar grains with O- and C-anomalous isotopic compositions in the matrices of the unequilibrated ordinary chondrites Semarkona (LL3.00), Meteorite Hills 00526 (L/LL3.05), and Northwest Africa 8276 (L3.00). The matrices of even the most primitive ordinary chondrites have been aqueously altered and/or thermally metamorphosed, destroying their presolar grain populations to varying extents. In addition to randomly placed isotope maps, we specifically targeted recently reported, relatively pristine Semarkona matrix areas to better explore the original inventory of presolar grains in this meteorite. In all samples, we found a total of 122 O-anomalous grains (silicates + oxides), 79 SiC grains, and 22 C-anomalous carbonaceous grains (organics, graphites). Average matrix-normalized abundances with 1σ uncertainties are 151-46+50 ppm O-anomalous grains, 53-12+14 ppm SiC grains and 56-14+19 ppm carbonaceous grains in Semarkona, 55-10+11 ppm (O-anom.), 22-4+5 ppm (SiC) and 3-1+2 ppm (carb.) in MET 00526 and 12-3+6 ppm (O-anom.), 15-5+7 ppm (SiC) and 1-1+3 ppm (carb.) in NWA 8276. In relatively pristine ordinary chondrites and in primitive carbonaceous and C-ungrouped chondrites, the O and C isotopic composition of presolar grains and their matrix-normalized abundances are similar, despite the likely differences in chondrite-formation time and nebular location. These results suggest a relatively homogenous distribution of presolar dust across major chondrite-forming reservoirs in the solar nebula. Secondary asteroidal processes are mainly responsible for differences in presolar grain abundances between and within chondrites, highlighting the need to identify and target the most pristine chondrite matrices for such studies.