Hasil untuk "Organic chemistry"

GU Qi-chun1, HE Wen-hui1, WANG Xiang1, ZHUANG Bing-jian2, ZHANG Jie2

EP 200 fabric core conveyor belt as the research object, firstly the sample data of stress and strain were obtained through tensile strength test, secondly the data distribution was preliminary tested using QQ chart, and then the kernel density fitting probability distribution was used to verify the K-S fitting degree and correctness of the data, and finally the process capacity index of the fabric core conveyor belt was calculated. The results showed that the tensile strength distribution of the fabric core conveyor belt roughly followed a normal distribution, the kernel density estimation method could effectively solve the problem of insufficient sample data and had certain advantages in engineering, and the process capacity index could not match the yield rate of the product. Further analysis of the factors affecting the stability of full- thickness tensile strength would be beneficial for optimizing the production of conveyor belts.

Ruixue Zhang, Yunxiao Xie, Miao Zhang et al.

Abstract Myopia is a serious public health issue worldwide. Damage to retinal ganglion cells (RGCs) in the retina induces degeneration of the visual cortex, which is known as anterograde trans-synaptic degeneration (TSD). However, the role of TSD in myopia is still unknown. Here single-cell RNA-sequencing revealed the activation of RGC apoptotic signals in the retinal ganglion and the remodeling of synapses in the visual cortex in myopia. The thickness of the retinal nerve fiber layer was negatively correlated with the degree of damage to the visual cortex and damage to neurons in the visual pathway and to the synaptic structure and function of the visual cortex indicated the occurrence of anterograde TSD in the visual pathway. The knockdown of Fos, which inhibited retinal neuronal apoptosis, suppressed TSD, indicating that myopia can aggravate RGC apoptosis, induce anterograde TSD and thus aggravate synaptic remodeling. Our findings provide a new experimental basis for understanding the pathogenesis of myopia.

Ivan Lednev, Sergey Zaitsev, Ekaterina Maltseva et al.

The development of materials based on chitosan and polyesters that possess thermoplastic, biocompatible, and biodegradable properties is a perspective for additive technologies in biomedicine. Research on obtaining such compositions is constrained because the polysaccharide content does not exceed 5 wt.%, which cannot ensure effective tissue regeneration. Herein, we propose a method for obtaining thermoplastic block copolymers based on chitosan and poly(ε-caprolactone) by ultrasonic irradiation of a homogeneous solution of a homopolymer mixture in dimethyl sulfoxide as a common solvent, achieving a yield of 99%. The distinctive feature of the method is the interaction between the components at the molecular level and provides obtaining copolymers at any component ratio. SEM images revealed a homogeneous structure without structural defects in both solvent-cast films and extruded filaments. The block copolymers were characterized by high mechanical property tensile strength of up to 60–70 MPa and elasticity of up to 35% for films and 25–40 MPa and elasticity of up to 50% for filaments. Cell adhesion of composition investigated on fibroblast cells (hTERT BJ-5TA) is at the level of chitosan and demonstrated the absence of cytotoxicity.

Zhihua Qiao, Xiancheng Wang, Hongli Zhao et al.

Abstract Background Exosomes (Exos) from adipose-derived stem cells (ADSCs) have a high inclusion content and low immunogenicity, which helps to control inflammation and accelerate the healing of wounds. Unfortunately, the yield of exosomes is poor, which raises the expense and lengthens the treatment period in addition to impairing exosomes’ therapeutic impact. Thus, one of the key problems that needs to be resolved in the current exosome study is increasing the exosome yield. Methods Tetraspanin-6 (TSPAN6) overexpression and knockdown models of ADSCs were constructed to determine the number of exosomes secreted by each group of cells as well as the number of multivesicular bodies (MVBs) and intraluminal vesicles (ILVs) within the cells. Subsequently, the binding region of the interaction between TSPAN6 and syntenin-1 was identified using the yeast two-hybrid assay, and the interaction itself was identified by immunoprecipitation. Finally, cellular and animal studies were conducted to investigate the role of each class of exosomes. Results When compared to the control group, the number of intracellular MVBs and ILVs was significantly larger, and the number of ADSCsTSPAN6+-Exos was more than three times higher. However, TSPAN6’s ability to stimulate exosome secretion was reduced as a result of syntenin-1 knockdown. Additional yeast two-hybrid assay demonstrated that the critical structures for their interaction were the N-terminal, Postsynaptic density protein 95/Discs large protein/Zonula occludens 1 (PDZ1), and PDZ2 domains of syntenin-1, and the C-terminal of TSPAN6. In animal trials, the wound healing rate was best in the ADSCsTSPAN6+-Exos group, while cellular experiments demonstrated that ADSCsTSPAN6+-Exos better enhanced the proliferation and migration of human skin fibroblasts (HSFs) and human umbilical vein endothelial cells (HUVECs). Conclusion TSPAN6 stimulates exosome secretion and formation, as well as the creation of MVBs and ILVs in ADSCs. Syntenin-1 is essential for TSPAN6’s stimulation of ADSCs-Exos secretion. Furthermore, ADSCsTSPAN6+-Exos has a greater ability to support wound healing, angiogenesis, and the proliferation and migration of a variety of cells.

Shaukat Ali Jawaid, Masood Jawaid

There are numerous well-established parameters to judge and evaluate the standard of a medical journal like quality of its contents and geographic distribution of manuscripts, it attracts for publication, indexation and coverage in important indexes and databases like Medline, Web of Sciences by Clarivate known for its Impact Factor (IF), PubMed Central, Scopus etc., journal visibility and readership, timely regular publication. Impact Factor is one of the criteria and not the only criteria, which should be used to judge the standard of a journal. However, too much importance being given to the  Impact Factor by the regulatory bodies in Pakistan as well as by medical institutions, asking those doing PhD to publish their research work in Impact Factor journals has created a crisis like situation not only for the researchers but also made the life of the IF journal editors miserable. They are under tremendous pressure to accommodate more and more papers by the authors anxious for early publication to meet certain deadlines for the completion of their research project and award of degrees while the editors on their part are faced with a dilemma due to human resource and financial resource constraints. In an environment where political stability remains in short supply most of the time, law and order situation is unpredictable, not to forget the frequent breakdown of electricity and inefficient internet service, it is not possible to either increase the frequency of publications or plan some other measures which all call for additional investment. Finding trained human resource and then retaining those remains a constant problem.

Dominik Duczmal, Aleksandra Bazan-Wozniak, Krystyna Niedzielska et al.

Cannabinoids represent a highly researched group of plant-derived ingredients. The substantial investment of funds from state and commercial sources has facilitated a significant increase in knowledge about these ingredients. Cannabinoids can be classified into three principal categories: plant-derived phytocannabinoids, synthetic cannabinoids and endogenous cannabinoids, along with the enzymes responsible for their synthesis and degradation. All of these compounds interact biologically with type 1 (CB1) and/or type 2 (CB2) cannabinoid receptors. A substantial body of evidence from in vitro and in vivo studies has demonstrated that cannabinoids and inhibitors of endocannabinoid degradation possess anti-inflammatory, antioxidant, antitumour and antifibrotic properties with beneficial effects. This review, which spans the period from 1940 to 2024, offers an overview of the potential therapeutic applications of natural and synthetic cannabinoids. The development of these substances is essential for the global market of do-it-yourself drugs to fully exploit the promising therapeutic properties of cannabinoids.

Juliana Botelho Moreira, Thaisa Duarte Santos, Camila Gonzales Cruz et al.

The use of natural polymers has increased due to concern about environmental pollution caused by plastics and emerging pollutants from fossil fuels. In this context, polysaccharides from macroalgae and microalgae arise as natural and abundant resources for various biological, biomedical, and food applications. Different nanomaterials are produced from these polysaccharides to act as effective carriers in the food and pharmaceutical industry: drug and nutrient carriers, active compound encapsulation, and delivery of therapeutic agents to tumor tissues. Polysaccharides-based nanomaterials applied as functional ingredients incorporated into foods can improve texture properties and decrease the caloric density of food products. These nanostructures also present the potential for developing food packaging with antioxidant and antimicrobial properties. In addition, polysaccharides-based nanomaterials are biocompatible, biodegradable, and safe for medical practices to prevent and manage various chronic diseases, such as diabetes, obesity, and cardiovascular disease. In this sense, this review article addresses the use of algal polysaccharides for manufacturing nanomaterials and their potential applications in food and biomedical areas. In addition, the paper discusses the general aspects of algae as a source of polysaccharides, the nanomaterials produced from these polymers, as well as recent studies and the potential use of algal polysaccharides for industries.

Valentina Trovato, Silvia Sfameni, Giulia Rando et al.

In recent years thanks to the Internet of Things (IoT), the demand for the development of miniaturized and wearable sensors has skyrocketed. Among them, novel sensors for wearable medical devices are mostly needed. The aim of this review is to summarize the advancements in this field from current points of view, focusing on sensors embedded into textile fabrics. Indeed, they are portable, lightweight, and the best candidates for monitoring biometric parameters. The possibility of integrating chemical sensors into textiles has opened new markets in smart clothing. Many examples of these systems are represented by color-changing materials due to their capability of altering optical properties, including absorption, reflectance, and scattering, in response to different external stimuli (temperature, humidity, pH, or chemicals). With the goal of smart health monitoring, nanosized sol–gel precursors, bringing coupling agents into their chemical structure, were used to modify halochromic dyestuffs, both minimizing leaching from the treated surfaces and increasing photostability for the development of stimuli-responsive sensors. The literature about the sensing properties of functionalized halochromic azo dyestuffs applied to textile fabrics is reviewed to understand their potential for achieving remote monitoring of health parameters. Finally, challenges and future perspectives are discussed to envisage the developed strategies for the next generation of functionalized halochromic dyestuffs with biocompatible and real-time stimuli-responsive capabilities.

Wei Sha, Timothy Bertram, Deepak Jain et al.

Abstract Background Selected renal cells (SRC) are in Phase II clinical trials as a kidney-sourced, autologous, tubular epithelial cell-enriched cell-based therapy for chronic kidney disease (CKD). In preclinical studies with rodent models of CKD, SRC have been shown to positively modulate key renal biomarkers associated with development of the chronic disease condition. Methods A comparative bioinformatic analysis of transcripts specifically enriched or depleted in SRC component sub-populations relative to the initial, biopsy-derived cell source was conducted. Results Outcomes associated with therapeutically relevant bioactivity from a systematic, genome-wide transcriptomic profiling of rodent SRC are reported. Key transcriptomic networks and concomitant signaling pathways that may underlie SRC mechanism of action as manifested by reparative, restorative, and regenerative bioactivity in rodent models of chronic kidney disease are identified. These include genes and gene networks associated with cell cycle control, transcriptional control, inflammation, ECM–receptor interaction, immune response, actin polymerization, regeneration, cell adhesion, and morphogenesis. Conclusions These data indicate that gene networks associated with development of the kidney are also leveraged for SRC regenerative bioactivity, providing evidence of potential mechanisms of action.

Li Feng, Shujia Yu, Hai Wang et al.

As a significant co-activator involved in cell cycle and cell growth, differentiation and development, p300/CBP has shown extraordinary potential target in cancer therapy. Herein we designed new compounds from the lead compound A-485 based on molecular dynamic simulations. A series of new spirocyclic chroman derivatives was prepared, characterized and proven to be a potential treatment of prostate cancer. The most potent compound <b>B16</b> inhibited the proliferation of enzalutamide-resistant 22Rv1 cells with an IC₅₀ value of 96 nM. Furthermore, compounds <b>B16</b>–<b>P2</b> displayed favorable overall pharmacokinetic profiles, and better tumor growth inhibition than A-485 in an in vivo xenograft model.

Hao Song, Xiaodong Ding, Zixian Cui et al.

Acoustic metamaterials are materials with artificially designed structures, which have characteristics that surpass the behavior of natural materials, such as negative refraction, anomalous Doppler effect, plane focusing, etc. This article mainly introduces and summarizes the related research progress of acoustic metamaterials in the past two decades, focusing on meta-atomic acoustic metamaterials, metamolecular acoustic metamaterials, meta-atomic clusters and metamolecule cluster acoustic metamaterials. Finally, the research overview and development trend of acoustic metasurfaces are briefly introduced.

Xuqiang Ji, Ting Wang, Qian Liu et al.

Abstract Renewable‐electricity‐driven N2 reduction is an attractive approach for ambient NH3 synthesis, but active electrocatalysts are needed to enable the N2 reduction reaction. Monolithic electrodes with active components anchored on conductive supports provide many advantages like structural stability, large surface area, and low electrical resistance. Here, a novel “oxidation‐etching” strategy is proposed to carve the surface of Cu foam into structures of particles, cubes, and sheets for N2 reduction electrocatalysis. The optimal catalyst achieves a Faradic efficiency as high as 18% at −0.35 V vs reversible hydrogen electrode (RHE) and a large NH3 yield of 2.45 × 10−10 mol s−1 cm−1 at −0.40 V vs RHE in 0.1 M HCl. Notably, it also shows superior long‐term electrochemical durability, with the preservation of electro‐activity for at least 20 hours.

Simon Rosowski, Stefan Becker, Lars Toleikis et al.

Abstract Background Yeast surface display (YSD) has proven to be a versatile platform technology for antibody discovery. However, the construction of antibody Fab libraries typically is a tedious three-step process that involves the generation of heavy chain as well as light chain display plasmids in different haploid yeast strains followed by yeast mating. Results Within this study, we aimed at implementing a focused Golden Gate Cloning approach for the generation of YSD libraries. For this, antibodies heavy and light chains were encoded on one single plasmid. Fab display on yeast cells was either mediated by a two-directional promoter system (2dir) or by ribosomal skipping (bicis). The general applicability of this methodology was proven by the functional display of a therapeutic antibody. Subsequently, we constructed large antibody libraries with heavy chain diversities derived from CEACAM5 immunized animals in combination with a common light chain. Target-specific antibodies from both display systems were readily obtained after three rounds of fluorescence activated cell sorting. Isolated variants exhibited high affinities in the nanomolar and subnanomolar range as well as appropriate biophysical properties. Conclusion We demonstrated that Golden Gate Cloning appears to be a valid tool for the generation of large yeast surface display antibody Fab libraries. This procedure simplifies the hit discovery process of antibodies from immune repertoires.

Jan Choutka, Radek Pohl, Kamil Parkan

Agnieszka E. Laudy, Ewa Kulińska, Stefan Tyski

The potential role of non-antibiotic medicinal products in the treatment of multidrug-resistant Gram-negative bacteria has recently been investigated. It is highly likely that the presence of efflux pumps may be one of the reasons for the weak activity of non-antibiotics, as in the case of some non-steroidal anti-inflammatory drugs (NSAIDs), against Gram-negative rods. The activity of eight drugs of potential non-antibiotic activity, active substance standards, and relevant medicinal products were analysed with and without of efflux pump inhibitors against 180 strains of five Gram-negative rod species by minimum inhibitory concentration (MIC) value determination in the presence of 1 mM MgSO4. Furthermore, the influence of non-antibiotics on the susceptibility of clinical strains to quinolones with or without PAβN (Phe-Arg-β-naphthylamide) was investigated. The impacts of PAβN on the susceptibility of bacteria to non-antibiotics suggests that amitriptyline, alendronate, nicergoline, and ticlopidine are substrates of efflux pumps in Gram-negative rods. Amitriptyline/Amitriptylinum showed the highest direct antibacterial activity, with MICs ranging 100–800 mg/L against all studied species. Significant decreases in the MIC values of other active substances (acyclovir, atorvastatin, and famotidine) tested with pump inhibitors were not observed. The investigated non-antibiotic medicinal products did not alter the MICs of quinolones in the absence and in the presence of PAβN to the studied clinical strains of five groups of species.

Ruibin Hou, Xiaohong Shang, Yan Xia et al.

The title compound was prepared via a cross-coupling reaction and its crystal structure has been determined. It crystallized in the triclinic space group P-1 with cell parameters: a = 8.552(2) Å, b = 11.310(2) Å, c = 16.150(3) Å, α = 109.55(3)°, β = 91.45(3)°, γ = 91.28(3)°, V = 1470.6(5) Å3, Z = 2 at 296 K. There is one molecule in the asymmetric unit. In the crystal structure, the neighboring molecules from dimers by weak intermolecular π···π interactions between the pyrrole and tetrathiafulvalene units. The dimers are further linked through C-H···π interactions to generate one-dimensional chains along the [100] direction. The arrangement of the molecules corresponds to an overlap between the HOMO and LUMO.

Alicja Tymoszuk, Małgorzata Zalewska

In mutation breeding of chrysanthemum the regeneration in vitro of adventitious shoots from ligulate florets can lead to the separation of chimera components and, as a result, to producing a new original cultivar. The success of that method considerably depends on the result being the number of the shoots formed. The more is produced, the greater the chances for an effective separation of chimera components and creating a new stable cultivar. The present research defines the effect of such factors as the inflorescence development stage, the type of the explant as well as the position of its inoculation on the increase in the efficiency of adventitious shoots regeneration. The ligulate florets of Chrysanthemum × grandiflorum (Ramat.) Kitam. ‘Cool Time’ were inoculated on the Murashige and Skoog [1962] medium supplemented with 2 mg·dm-3 BAP and 0.5 mg·dm-3 NAA. There was shown no significant effect of the inflorescence development stage (incompletely open with a partially visible disk or with the entire visible disk in which tubular florets do not produce pollen or completely open in which two or half of the whorls of tubular florets produce pollen) on the shoot regeneration efficiency. Most shoots regenerate on transversely- or lengthwise-cut into half or on the entire pierced ligulate florets – horizontally inoculated, with the abaxial side on the medium.

Stewart C. Whitman, Alan Daugherty, Steven R. Post

Class A scavenger receptors (SR-A) mediate the uptake of modified low density lipoprotein (LDL) by macrophages. Although not typically associated with the activation of intracellular signaling cascades, results with peritoneal macrophages indicate that the SR-A ligand acetylated LDL (AcLDL) promotes activation of cytosolic kinases and phospholipases. These signaling responses were blocked by the treatment of cells with pertussis toxin (PTX) indicating that SR-A activates Gi/o-linked signaling pathways. The functional significance of SR-A-mediated Gi/o activation is not clear. In this study, we investigated the potential role of Gi/o activation in regulating SR-A-mediated lipoprotein uptake. Treatment of mouse peritoneal macrophages with PTX decreased association of fluorescently labeled AcLDL with cells. This inhibition was dependent on the catalytic activity of the toxin confirming that the decrease in AcLDL uptake involved inhibiting Gi/o activation. In contrast to the inhibitory effect on AcLDL uptake, PTX treatment did not alter β-VLDL-induced cholesterol esterification or deposition of cholesterol. The ability of polyinosine to completely inhibit AcLDL uptake, and the lack of PTX effect on β-VLDL uptake, demonstrated that the inhibitory effect is specific for SR-A and not the result of non-specific effects on lipoprotein metabolism. Despite having an effect on an SR-A-mediated lipoprotein uptake, there was no change in the relative abundance of SR-A protein after PTX treatment. These results demonstrate that activation of a PTX-sensitive G protein is involved in a feedback process that positively regulates SR-A function.—Whitman, S. C., A. Daugherty, and S. R. Post. Regulation of acetylated low density lipoprotein uptake in macrophages by pertussis toxin-sensitive G proteins. J. Lipid Res. 2000. 41: 807–813.

S. Rajesh, Jyoti Srivastava, Biswadip Bannerji et al.

Nancy R. Webb, Maria C. de Beer, Bela F. Asztalos et al.

Scavenger receptor class B type I (SR-BI) mediates the selective transfer of cholesteryl ester from HDL to cells. We previously established that SR-BI overexpressed in livers of apolipoprotein A-I-deficient mice processes exogenous human HDL2 to incrementally smaller HDL particles. When mixed with normal mouse plasma either in vivo or ex vivo, SR-BI-generated HDL “remnants” rapidly remodel to form HDL-sized lipoproteins. In this study, we analyzed HDLs throughout the process of HDL remnant formation and investigated the mechanism of conversion to larger particles. Upon interacting with SR-BI, α-migrating HDL2 is initially converted to a preα-migrating particle that is ultimately processed to a smaller α-migrating HDL remnant. SR-BI does not appear to generate preβ-1 HDL particles. When incubated with isolated lipoprotein fractions, HDL remnants are converted to lipoprotein particles corresponding in size to the particle incubated with the HDL remnant. HDL remnant conversion is not altered in phospholipid transfer protein (PLTP)-deficient mouse plasma or by the addition of purified PLTP. Although LCAT-deficient plasma promoted only partial conversion, this deficiency was attributable to the nature of HDL particles in LCAT−/− mice rather than to a requirement for LCAT in the remodeling process.We conclude that HDL remnants, generated by SR-BI, are converted to larger particles by rapidly reassociating with existing HDL particles in an enzyme-independent manner.