Recent improvements in the development of A<Subscript>2B</Subscript> adenosine receptor agonists

Adenosine is known to exert most of its physiological functions by acting as local modulator at four receptor subtypes named A₁, A_2A, A_2B and A₃ (ARs). Principally as a result of the difficulty in identifying potent and selective agonists, the A_2B AR is the least extensively characterised of the adenosine receptors family. Despite these limitations, growing understanding of the physiological meaning of this target indicates promising therapeutic perspectives for specific ligands. As A_2B AR signalling seems to be associated with pre/postconditioning cardioprotective and anti-inflammatory mechanisms, selective agonists may represent a new therapeutic group for patients suffering from coronary artery disease. Herein we present an overview of the recent advancements in identifying potent and selective A_2B AR agonists reported in scientific and patent literature. These compounds can be classified into adenosine-like and nonadenosine ligands. Nucleoside-based agonists are the result of modifying adenosine by substitution at the N ⁶-, C²-positions of the purine heterocycle and/or at the 5′-position of the ribose moiety or combinations of these substitutions. Compounds 1-deoxy-1-{6-[N′-(furan-2-carbonyl)-hydrazino]-9H-purin-9-yl}-N-ethyl-β-D-ribofuranuronamide (19, hA₁ K _i = 1050 nM, hA_2A K _i = 1550 nM, hA_2B EC₅₀ = 82 nM, hA₃ K _i > 5 μM) and its 2-chloro analogue 23 (hA₁ K _i = 3500 nM, hA_2A K _i = 4950 nM, hA_2B EC₅₀ = 210 nM, hA₃ K _i > 5 μM) were confirmed to be potent and selective full agonists in a cyclic adenosine monophosphate (cAMP) functional assay in Chinese hamster ovary (CHO) cells expressing hA_2B AR. Nonribose ligands are represented by conveniently substituted dicarbonitrilepyridines, among which 2-[6-amino-3,5-dicyano-4-[4-(cyclopropylmethoxy)phenyl]pyridin-2-ylsulfanyl]acetamide (BAY-60–6583, hA₁, hA_2A, hA₃ EC₅₀ > 10 μM; hA_2B EC₅₀ = 3 nM) is currently under preclinical-phase investigation for treating coronary artery disorders and atherosclerosis.     

Effect of tidal volume on distribution of ventilation assessed by synchrotron radiation CT in rabbit.

A respiration-gated synchrotron radiation computed tomography (SRCT) technique, which allows visualization and direct quantification of inhaled stable xenon gas, was used to study the effect of tidal volume (Vt) on regional lung ventilation. High-resolution maps (pixel size 0.35 x 0.35 mm) of local washin time constants (tau) and regional specific ventilation were obtained in five anesthetized, paralyzed, and mechanically ventilated rabbits in upright body position at the fourth, sixth, and eighth dorsal vertebral levels with a Vt from 4.9 +/- 0.3 to 7.9 +/- 0.4 ml/kg (means +/- SE). Increasing Vt without an increase in minute ventilation resulted in a proportional increase of mean specific ventilation up to 65% in all studied lung levels and reduced the scattering of washin tau values. The tau values had log-normal distributions. The results indicate that an increase in Vt decreases nonuniformity of intraregional ventilatory gas exchange. The findings suggest that (SRCT) provides a new quantitative tool with high spatial discrimination ability for assessment of changes in peripheral pulmonary gas distribution during mechanical ventilation.     

Improvement in infected wound healing in type 1 diabetic rat by the synergistic effect of photobiomodulation therapy and conditioned medium

We investigated the effects of photobiomodulation therapy (PBMT) and conditioned medium (CM) of human bone marrow mesenchymal stem cells (hBM-MSC) individually and/or in combination on the stereological parameters and the expression of basic fibroblast growth factor (bFGF), hypoxia-inducible factor (HIF-1α), and stromal cell–derived factor-1α (SDF-1α) in a wound model infected with methicillin-resistant Staphylococcus aureus (MRSA) in diabetic rats. CM was provided by culturing hBM-MSCs. Type 1 diabetes mellitus (T1DM) was induced in 72 rats, divided into four groups, harboring 18 rats each: group 1 served as a control group, group 2 received PBMT, group 3 received CM, and group 4 received CM + PBMT. On days 4, 7, and 15, six animals from each group were euthanized and the skin samples were separated for stereology examination and gene expression analysis by real-time polymerase chain reaction. In the CM + PBMT, CM, and PBMT groups, significant decreases were induced in the number of neutrophils (1460 ± 93, 1854 ± 138, 1719 ± 248) and macrophages (539 ± 69, 804 ± 63, 912 ± 41), and significant increases in the number of fibroblasts (1073 ± 116, 836 ± 75, 912 ± 41) and angiogenesis (15 230 ± 516, 13 318 ± 1116, 14 041 ± 867), compared with those of the control group (2690 ± 371, 1139 ± 145, 566 ± 90, 12 585 ± 1219). Interestingly, the findings of the stereological examination in the CM + PBMT group were statistically more significant than those in the other groups. In the PBMT group, in most cases, the expression of bFGF, HIF-1α, and SDF-1α, on day 4 (27.7 ± 0.14, 28.8 ± 0.52, 27.5 ± 0.54) and day 7 (26.8 ± 1.4, 29.6 ± 1.4, 28.3 ± 1.2) were more significant than those in the control (day 4, 19.3 ± 0.42, 25.5 ± 0.08, 22.6 ± 0.04; day 7, 22.3 ± 0.22, 28.3 ± 0.59, 24.3 ± 0.19) and other treatment groups. The application of PBMT + CM induced anti-inflammatory and angiogenic activities, and hastened wound healing process in a T1 DM model of MRSA infected wound.     

Genome structure and evolution in the cruciferous tribe Thlaspideae (Brassicaceae)

Whole-genome duplications (WGDs) and chromosome rearrangements (CRs) play the key role in driving the diversification and evolution of plant lineages. Although the direct link between WGDs and plant diversification is well documented, relatively few studies focus on the evolutionary significance of CRs. The cruciferous tribe Thlaspideae represents an ideal model system to address the role of large-scale chromosome alterations in genome evolution, as most Thlaspideae species share the same diploid chromosome number (2n = 2x = 14). Here we constructed the genome structure in 12 Thlaspideae species, including field pennycress (Thlaspi arvense) and garlic mustard (Alliaria petiolata). We detected and precisely characterized genus- and species-specific CRs, mostly pericentric inversions, as the main genome-diversifying drivers in the tribe. We reconstructed the structure of seven chromosomes of an ancestral Thlaspideae genome, identified evolutionary stable chromosomes versus chromosomes prone to CRs, estimated the rate of CRs, and uncovered an allohexaploid origin of garlic mustard from diploid taxa closely related to A. petiolata and Parlatoria cakiloidea. Furthermore, we performed detailed bioinformatic analysis of the Thlaspideae repeatomes, and identified repetitive elements applicable as unique species- and genus-specific barcodes and chromosome landmarks. This study deepens our general understanding of the evolutionary role of CRs, particularly pericentric inversions, in plant genome diversification, and provides a robust base for follow-up whole-genome sequencing efforts.     

Impaired spermatogenesis associated with changes in spatial arrangement of Sertoli and spermatogonial cells following induced diabetes

The current study was conducted to assess the relationship between testicular cells in spermatogenesis, through which the production of healthy and mature sperm is essential. However, it seems necessary to obtain more information about the three-dimensional pattern of the testis cells arrangement, which is directly related to the function of the testis after induction of diabetes. Twelve adult mice (28-30 g) were assigned into two experimental groups: (1) control and (2) diabetic (40 mg/kg STZ). The epididymal sperm collected from the tail of the epididymis and testes samples were taken for stereology, immunocytochemistry and RNA extraction. Our data showed that diabetes could notably decrease the number of testicular cells, together with a reduction of total sperm count. In addition, the results from the second-order stereology indicated the significant changes in the spatial arrangement of Sertoli cells and spermatogonial cells in the diabetic groups, in comparison with the control (P < .05). Moreover, the immunohistochemistry results showed a significant reduction in Sex-determining Region Y (SRY) box 9 gene (SOX9), vimentin, occludin, and connexin-43 positive cells in the diabetic groups compared with the control (P < .05). Furthermore, our data showed that the expression of steroidogenic acute regulatory protein steroidogenic acute regulatory protein (StAR) and peripheral benzodiazepine receptor peripheral benzodiazepine receptor (PBR) was significantly reduced in the diabetic groups, in comparison with the control (P < .05). These findings suggest that structural and functional changes of testis cells after induction of diabetes cause the alterations in the spatial arrangement of Sertoli and spermatogonial cells, ultimately influencing the normal spermatogenesis in mice.     

Citrinin detection by intensified fluorescence signal of a FRET-based immunosensor using magnetic/silica core–shell

The specific immune-reaction between the anti-citrinin antibody immobilized on the surface of magnetic/silica core–shell (MSCS) and the citrinin–Rho123–BSA conjugate brings the Rho123 fluorophore as an acceptor and the QDs as a donor in close spatial proximity and causes FRET for occurring upon photo-excitation of the QDs. The novelties of this study include: (1) immobilization of the MSCS; (2) large amount of the immobilized QDs, and (3) immobilization of a large amount of Rho123 on the BSA macromolecule. Cd/Te QDs were synthesized by the simultaneous reduction of cadmium chloride and tellurium in the presence of sodium borohydride. Magnetic nanoparticles were synthesized using FeSO₄ and FeCl₃. The prepared magnetic nanoparticles shelled by silica using tetraethoxysilane in the presence of ammonia. Transmission electron microscopy (TEM) analysis was used for investigating shape and monodispersity of the nanoparticles. EDC/NHS was used as a cross linking agent for immobilization of the QDs, conjugation of citrinin to amino groups of BSA, labeling of BSA with Rho123 and also for immobilization of the amino-functionalized MSCS on the immobilized QDs. Immobilization of the anti-citrinin antibody on the surface of the amino-functionalized MSCS was performed by Schiff-base mechanism. By using these three effective strategies, sensitivity of the designed nanobiosensor was incredibly enhanced as a very low limit of detection (up to 0.1 pM). The feasibility of this technique was tested by the detection of citrinin in the spiked human serum. Results showed that there was a linear correlation between the decreased fluorescence intensity of the Rho123 and increased fluorescence intensity of the QDs with increasing concentration of citrinin in the spiked samples in the range of 1–6 pM. According to obtained results, we conclude that this highly sensitive detection scheme is a easy, quick and impressive method that can be used in optical-based nanosensors.     

Hypoxia-Targeting Drug Evofosfamide (TH-302) Enhances Sunitinib Activity in Neuroblastoma Xenograft Models

Antiangiogenic therapy has shown promising results in preclinical and clinical trials. However, tumor cells acquire resistance to this therapy by gaining ability to survive and proliferate under hypoxia induced by antiangiogenic therapy. Combining antiangiogenic therapy with hypoxia-activated prodrugs can overcome this limitation. Here, we have tested the combination of antiangiogenic drug sunitinib in combination with hypoxia-activated prodrug evofosfamide in neuroblastoma. In vitro, neuroblastoma cell line SK-N-BE(2) was 40-folds sensitive to evofosfamide under hypoxia compared to normoxia. In IV metastatic model, evofosfamide significantly increased mice survival compared to the vehicle (P=.02). In SK-N-BE(2) subcutaneous xenograft model, we tested two different treatment regimens using 30 mg/kg sunitinib and 50 mg/kg evofosfamide. Here, sunitinib therapy when started along with evofosfamide treatment showed higher efficacy compared to single agents in subcutaneous SK-N-BE(2) xenograft model, whereas sunitinib when started 7 days after evofosfamide treatment did not have any advantage compared to treatment with either single agent. Immunofluorescence of tumor sections revealed higher number of apoptotic cells and hypoxic areas compared to either single agent when both treatments were started together. Treatment with 80 mg/kg sunitinib with 50 mg/kg evofosfamide was significantly superior to single agents in both xenograft and metastatic models. This study confirms the preclinical efficacy of sunitinib and evofosfamide in murine models of aggressive neuroblastoma. Sunitinib enhances the efficacy of evofosfamide by increasing hypoxic areas, and evofosfamide targets hypoxic tumor cells. Consequently, each drug enhances the activity of the other.