Heterogeneous Tissue Distribution Research Articles

Quantitative pulmonary pharmacokinetics of tetrandrine for SARS-CoV-2 repurposing: a physiologically based pharmacokinetic modeling approach.

Tetrandrine (TET) has been traditionally used in China as a medication to treat silicosis and has recently demonstrated anti-SARS-CoV-2 potential in vitro. By recognizing the disparity between in vitro findings and in vivo performance, we aimed to estimate the free lung concentration of TET using a physiologically based pharmacokinetic (PBPK) model to link in vitro activity with in vivo efficacy. Comparative pharmacokinetic studies of TET were performed in rats and dogs to elucidate the pharmacokinetic mechanisms as well as discern interspecies variations. These insights facilitated the creation of an animal-specific PBPK model, which was subsequently translated to a human model following thorough validation. Following validation of the pharmacokinetic profile from a literature report on single oral dosing of TET in humans, the plasma and lung concentrations were predicted after TET administration at approved dosage levels. Finally, the antiviral efficacy of TET in humans was assessed from the free drug concentration in the lungs. Both in vivo and in vitro experiments thus confirmed that the systemic clearance of TET was primarily through hepatic metabolism. Additionally, the lysosomal capture of basic TET was identified as a pivotal factor in its vast distribution volume and heterogeneous tissue distribution, which could modulate the absorption dynamics of TET in the gastrointestinal tract. Notably, the PBPK-model-based unbound lung concentration of TET (1.67-1.74μg/mL) at the recommended clinical dosage surpassed the in vitro threshold for anti-SARS-CoV-2 activity (EC90 = 1.52μg/mL). Thus, a PBPK model was successfully developed to bridge the in vitro activity and in vivo target exposure of TET to facilitate its repurposing.

Recent developments in bioprocessing of recombinant antibody fragments

Biotechnological and biomedical applications of antibodies have been on a steady rise since the 1980s. As unique and highly specific bioreagents, monoclonal antibodies (mAbs) have been widely exploited and approved as therapeutic agents. However, the use of mAbs has limitations for therapeutic applications. Antibody fragments (AbFs) with preserved antigen-binding sites have a significant potential to overcome the disadvantages of conventional mAbs, such as heterogeneous tissue distribution after systemic administration, especially in solid tumors, and Fc-mediated bystander activation of the immune system. AbFs possess better biodistribution coefficient due to lower molecular weight. They preserve the functional features of mAbs, such as antigen specificity and binding, while at the same time, ensuring much better tissue penetration. An additional benefit of AbFs is the possibility of their production in bacterial and yeast cells due to the small size, more robust structure, and lack of posttranslational modifications. In this review, we described current approaches to the AbF production with recent examples of AbF synthesis in bacterial and yeast expression systems and methods for the production optimization.

Recent Developments in Bioprocessing of Recombinant Antibody Fragments.

Biotechnological and biomedical applications of antibodies have been on a steady rise since the 1980s. As unique and highly specific bioreagents, monoclonal antibodies (mAbs) have been widely exploited and approved as therapeutic agents. However, the use of mAbs has limitations for therapeutic applications. Antibody fragments (AbFs) with preserved antigen-binding sites have a significant potential to overcome the disadvantages of conventional mAbs, such as heterogeneous tissue distribution after systemic administration, especially in solid tumors, and Fc-mediated bystander activation of the immune system. AbFs possess better biodistribution coefficient due to lower molecular weight. They preserve the functional features of mAbs, such as antigen specificity and binding, while at the same time, ensuring much better tissue penetration. An additional benefit of AbFs is the possibility of their production in bacterial and yeast cells due to the small size, more robust structure, and lack of posttranslational modifications. In this review, we described current approaches to the AbF production with recent examples of AbF synthesis in bacterial and yeast expression systems and methods for the production optimization.

Dedicated cone-beam breast CT: Data acquisition strategies based on projection angle-dependent normalized glandular dose coefficients.

Dedicated cone-beam breast computed tomography (CBBCT) using short-scan acquisition is being actively investigated to potentially reduce the radiation dose to the breast. This would require determining the optimal x-ray source trajectory for such short-scan acquisition. To quantify the projection angle-dependent normalized glandular dose coefficient ( ) in CBBCT, referred to as angular , so that the x-ray ray source trajectory that minimizes the radiation dose to the breast for short-scan acquisition can be determined. A cohort of 75 CBBCT clinical datasets was segmented and used to generate three breast models - (I) patient-specific breast with heterogeneous fibroglandular tissue distribution and real breast shape, (II) patient-specific breast shape with homogeneous tissue distribution and matched fibroglandular weight fraction, and (III) homogeneous semi-ellipsoidal breast with patient-specific breast dimensions and matched fibroglandular weight fraction, which corresponds to the breast model used in current radiation dosimetry protocols. For each clinical dataset, the angular was obtained at 10 discrete angles, spaced 36° apart, for full-scan, circular, x-ray source trajectory from Monte Carlo simulations. Model III is used for validating the Monte Carlo simulation results. Models II and III are used to determine if breast shape contributes to the observed trends in angular . A geometry-based theory in conjunction with center-of-mass ( ) based distribution analysis is used to explain the projection angle-dependent variation in angular . The theoretical model predicted that the angular will follow a sinusoidal pattern and the amplitude of the sinusoid increases when the center-of-mass of fibroglandular tissue ( ) is farther from the center-of-mass of the breast ( ). It also predicted that the angular will be minimized at x-ray source positions complementary to the . The was superior to the in 80% (60/75) of the breasts. From Monte Carlo simulations and for homogeneous breasts (models II and III), the deviation in breast shape from a semi-ellipsoid had minimal effect on angular and showed less than 4% variation. From Monte Carlo simulations and for model I, as predicted by our theory, the angular followed a sinusoidal pattern with maxima and minima at x-ray source positions superior and inferior to the breast, respectively. For model I, the projection angle-dependent variation in angular was 16.4%. The heterogeneous tissue distribution affected the angular more than the breast shape. For model I, the angular was lowest when the x-ray source was inferior to the breast. Hence, for short-scan CBBCT acquisition with aligned with axis-of-rotation, an x-ray source trajectory inferior to the breast is preferable and such an acquisition spanning 205° can potentially reduce the mean glandular dose by up to 52%.

Fast inspection of fruits using nuclear magnetic resonance spectroscopy

AbstractHigh‐resolution nuclear magnetic resonance (NMR) spectroscopy is an indispensable technique for obtaining chemical structure information. Its quantitative and noninvasive properties have led to its growing popularity as an analytical tool in many fields, including biology, chemistry, medicine, and food science. During transportation and storage, chemical reactions among the many nutrients lead to a loss of food quality. In these circumstances, portable NMR spectrometers can readily be used for food inspection and quality control. Because of the heterogeneous tissue distribution in food, a high‐resolution NMR method is required for detailed food inspection. Therefore, in this study, we demonstrated the feasibility of using an intermolecular double‐quantum coherence signal to obtain high‐resolution metabolic profiles of several fruits, including grape, cantaloupe, tomato, and watermelon. The resulting high‐resolution NMR spectra facilitate the identification of important metabolites, which can be used as biomarkers for food quality control. The method established here may be adapted for food inspection using portable NMR equipment.

Practical Guide for Quantification of In Vivo Degradation Rates for Therapeutic Proteins with Single-Cell Resolution Using Fluorescence Ratio Imaging.

Many tools for studying the pharmacokinetics of biologics lack single-cell resolution to quantify the heterogeneous tissue distribution and subsequent therapeutic degradation in vivo. This protocol describes a dual-labeling technique using two near-infrared dyes with widely differing residualization rates to efficiently quantify in vivo therapeutic protein distribution and degradation rates at the single cell level (number of proteins/cell) via ex vivo flow cytometry and histology. Examples are shown for four biologics with varying rates of receptor internalization and degradation and a secondary dye pair for use in systems with lower receptor expression. Organ biodistribution, tissue-level confocal microscopy, and cellular-level flow cytometry were used to image the multi-scale distribution of these agents in tumor xenograft mouse models. The single-cell measurements reveal highly heterogeneous delivery, and degradation results show the delay between peak tumor uptake and maximum protein degradation. This approach has broad applicability in tracking the tissue and cellular distribution of protein therapeutics for drug development and dose determination.

Tissue-specific differences in metabolites and transcripts contribute to the heterogeneity of ricinoleic acid accumulation in Ricinus communis L. (castor) seeds.

Castor (Ricinus communis L.) seeds are valued for their production of oils which can comprise up to 90% hydroxy-fatty acids (ricinoleic acid). Castor oil contains mono-, di- and tri- ricinoleic acid containing triacylglycerols (TAGs). Although the enzymatic synthesis of ricinoleic acid is well described, the differential compartmentalization of these TAG molecular species has remained undefined. To examine the distribution of hydroxy fatty acid accumulation within the endosperm and embryo tissues of castor seeds. Matrix assisted laser desorption/ionization mass spectrometry imaging was used to map the distribution of triacylglycerols in tissue sections of castor seeds. In addition, the endosperm and embryo (cotyledons and embryonic axis) tissues were dissected and extracted for quantitative lipidomics analysis and Illumina-based RNA deep sequencing. This study revealed an unexpected heterogeneous tissue distribution of mono-, di- and tri- hydroxy-triacylglycerols in the embryo and endosperm tissues of castor seeds. Pathway analysis based on transcript abundance suggested that distinct embryo- and endosperm-specific mechanisms may exist for the shuttling of ricinoleic acid away from phosphatidylcholine (PC) and into hydroxy TAG production. The embryo-biased mechanism appears to favor removal of ricinoleic acid from PC through phophatidylcholine: diacylglycerol acyltransferase while the endosperm pathway appears to remove ricinoleic acid from the PC pool by preferences of phospholipase A (PLA2α) and/or phosphatidylcholine: diacylglycerol cholinephosphotransferase. Collectively, a combination of lipidomics and transcriptomics analyses revealed previously undefined spatial aspects of hydroxy fatty acid metabolism in castor seeds. These studies underscore a need for tissue-specific studies as a means to better understand the regulation of triacylglycerol accumulation in oilseeds.

The site of tumor development determines immunogenicity via temporal mobilization of antigen-laden dendritic cells in draining lymph nodes.

The elimination of solid tumors largely depends on effective T-cell priming by dendritic cells (DCs). For decades, studies focusing on antitumoral immune responses have been performed with tumors transplanted subcutaneously (s.c.). These studies however do not take into account the heterogeneous tissue distribution and functionality of the different DC subsets. Given the crucial role of DCs in inducing protective immune response, we postulated that the anatomic location of tumor development may greatly impact tumor immunogenicity. We therefore implanted tumor cells either in the DC-rich dermis environment or in the s.c. tissue that mainly contains macrophages and monocytes. We showed that intradermal (i.d.), but not s.c. tumors are rapidly rejected in a T-cell-dependent manner and induce protective T-cell responses. The rejection of i.d. tumors correlates with rapid recruitment of dermal DCs presenting the tumor antigen to both CD4 and CD8 T cells in the draining lymph nodes (dLNs). The same DC subsets were mobilized upon s.c. tumor transplantation but with delayed kinetics. Altogether, our results show that the anatomical site of tumor development influences tumor immunogenicity, notably by controlling the kinetics of DC mobilization in the draining LNs.

KRAS Mutant Allele-Specific Imbalance (MASI) assessment in routine samples of patients with metastatic colorectal cancer

AimsPatients with colorectal cancer harbouring KRAS mutations do not respond to antiepidermal growth factor receptor (anti-EGFR) therapy. Community screening for KRAS mutation selects patients for treatment. When a KRAS mutation...

TRPs in the kidney - location, location, location

TRPs in the kidney - location, location, location

Pharmacokinetics of Cefuroxime in Porcine Cortical and Cancellous Bone Determined by Microdialysis

Traditionally, the pharmacokinetics of antimicrobials in bone have been investigated using bone biopsy specimens, but this approach suffers from considerable methodological limitations. Consequently, new methods are needed. The objectives of this study were to assess the feasibility of microdialysis (MD) for measuring cefuroxime in bone and to obtain pharmacokinetic profiles for the same drug in porcine cortical and cancellous bone. The measurements were conducted in bone wax sealed and unsealed drill holes in cortical bone and in drill holes in cancellous bone and in subcutaneous tissue. As a reference, the free and total plasma concentrations were also measured. The animals received a bolus of 1,500 mg cefuroxime over 30 min. No significant differences were found between the key pharmacokinetic parameters for sealed and unsealed drill holes in cortical bone. The mean ± standard error of the mean area under the concentration-time curve (AUC) values from 0 to 5 h were 6,013 ± 1,339, 3,222 ± 1086, 2,232 ± 635, and 952 ± 290 min · μg/ml for free plasma, subcutaneous tissue, cancellous bone, and cortical bone, respectively (P < 0.01, analysis of variance). The AUC for cortical bone was also significantly different from that for cancellous bone (P = 0.04). This heterogeneous tissue distribution was also reflected in other key pharmacokinetic parameters. This study validates MD as a suitable method for measuring cefuroxime in bone. Cefuroxime penetration was impaired for all tissues, and bone may not be considered one distinct compartment.

Unsolved issues related to human mitochondrial diseases

Human mitochondrial diseases, defined as the diseases due to a mitochondrial oxidative phosphorylation defect, represent a large group of very diverse diseases with respect to phenotype and genetic causes. They present with many unsolved issues, the comprehensive analysis of which is beyond the scope of this review. We here essentially focus on the mechanisms underlying the diversity of targeted tissues, which is an important component of the large panel of these diseases phenotypic expression. The reproducibility of genotype/phenotype expression, the presence of modifying factors, and the potential causes for the restricted pattern of tissular expression are reviewed. Special emphasis is made on heteroplasmy, a specific feature of mitochondrial diseases, defined as the coexistence within the cell of mutant and wild type mitochondrial DNA molecules. Its existence permits unequal segregation during mitoses of the mitochondrial DNA populations and consequently heterogeneous tissue distribution of the mutation load. The observed tissue distributions of recurrent human mitochondrial DNA deleterious mutations are diverse but reproducible for a given mutation demonstrating that the segregation is not a random process. Its extent and mechanisms remain essentially unknown despite recent advances obtained in animal models.

Heterogeneous tissue distribution of a mitochondrial DNA polymorphism in heteroplasmic subjects without mitochondrial disorders

CONTEXTSeveral maternally inherited point mutations of the mitochondrial genome cause mitochondrial disorders, but the correlation between genotype and phenotype remains obscure in many cases. The same mutation may cause various...

Relative Importance of Inhalation and Ingestion as Sources of Uptake of 210Pb from the Environment

Dietary intake of 210 Pb is generally higher than inhalation intake, but fractional uptake to blood is higher from inhalation. In this study publications are reviewed in which both inhalation and ingestion intake of 210 Pb are measured. Concentrations of 210 Pb in bone are also given, where available. Up-to-date biokinetic information on Pb is used to evaluate fractional uptake from inhalation and ingestion, including consideration of the effect of aerosol particle size. Estimates are also given of 210 Pb uptake from domestic radon, alcoholic beverages and smoking. The difficulty in obtaining precise estimates of 210 Pb uptake is emphasised. On averagc, atmospheric inhalation, diet and domestic radon contribute 12, 86 and 2% of total 210 Pb uptake respectively. Alcoholic beverages and cigarettes can add a further 75%. Average committed effective dose from one year of 210 Pb intake to adults is 37 μSv, while committed dose equivalents to organs range widely from 380 μSv for bone surfaces to 5 μSv for most soft tissue reflecting the heterogeneous tissue distribution of Pb.