ABSTRACT
Self-assembly refers to the spontaneous process where basic units such as molecules and nanostructured materials form a stable and compact structure. Peptides can self-assemble by non-covalent driving forces to form various morphologies such as nanofibers, nano layered structures, and micelles. Peptide self-assembly technology has become a hot research topic in recent years due to the advantages of definite amino acid sequences, easy synthesis and design of peptides. It has been shown that the self-assembly design of certain peptide drugs or the use of self-assembled peptide materials as carriers for drug delivery can solve the problems such as short half-life, poor water solubility and poor penetration due to physiological barrier. This review summarizes the formation mechanism of self-assembled peptides, self-assembly morphology, influencing factors, self-assembly design methods and major applications in biomedical field, providing a reference for the efficient use of peptides.
Subject(s)
Pharmaceutical Preparations , Peptides/chemistry , Amino Acid Sequence , Nanostructures/chemistry , Drug Delivery SystemsABSTRACT
OBJECTIVE To systemically sort out the main practices of local drug online procurement， so as to provide reference for national and local governments to improve drug online procurement policies and drug price formation mechanism. METHODS By searching the official websites of 31 provincial medical security bureaus and drug-centralized procurement platforms in China， the classification methods and main goals of local drug online procurement were summarized， then the main practices of local drug online procurement were analyzed based on the main goals， and corresponding suggestion was put forward. RESULTS & CONCLUSIONS There were two classification methods of online drug procurement in each province， one is based on online or purchase methods， and the other is based on drug dimensions. Five main objectives of online drug procurement in each province are to ensure reasonable drug prices， meet clinical drug demand， ensure stable drug supply， cooperate with the implementation of drug policies， and standardize the behavior of transaction subjects. In order to achieve the five goals， each province has taken some targeted measures， but the severity of the policy varies greatly. In order to further improve the online drug procurement policy and improve the market-oriented online drug price formation mechanism， it is suggested to build the top-level design of online drug procurement， strengthen the management of the price comparison relationship of similar drugs， give full play to the monitoring function of the drug-centralized procurement platform and establish a national unified drug-centralized procurement platform.
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Hepatocellular carcinoma is a common malignant disease in clinical practice, and portal vein tumor thrombosis (PVTT) is one of the important factors affecting the prognosis of hepatocellular carcinoma. PVTT has strong oncologic characteristics and is highly susceptible to extrahepatic metastasis, complicating portal hypertension, leading to gastrointestinal bleeding or liver failure and causing death. In this paper, we review the formation mechanism of hepatocellular carcinoma combined with PVTT in terms of local anatomy, hemodynamics, molecular biology and tumor microenvironment to provide effective reference for clinical treatment.
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Gallstone is a common and frequent disease and frequent incidence, secondary infection and cancer seriously affect the health of patients. Academic organizations in different regions have issued multiple guidelines and consensus to promote the normative diagnosis and treatment of gallstones. However, in clinical practice, most symptomatic gallstones are treated, while the formation and prevention process of gallstones are ignored, making the concept of treating without a disease has not been strengthened.This article reviews the risk factors and mechanisms of gallstone formation, and points out the importance of effective prevention during stone formation. In the stage of gallstone formation, the high risk factors of stone formation can be analyzed through two aspects of injury factors and protective factors, and the high risk groups of stone formation can be screened out. According to the pathophysiological progression of gallstones, personalized prevention and follow-up strategies can be developed for the stone formation stage of gallstones.
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OBJECTIVE To prepar e and characterize danazol （DAZ）-sodium caseinate （SC）composite nanoparticles ，and to study the mechanism of preparing nanoparticles in “bottom-up”technology. METHODS SC was used as a stabilizer for regulating nanoparticles，so that DAZ-SC composite nanoparticles were prepared by anti-solvent precipitation method. The particle size ， Zeta-potential，micro-morphology，stability，encapsulation efficiency ，drug loading and in vitro dissolution rate were characterized. Fluorescence spectra ，IR spectra ，FBRM and other methods were used to analyze the interaction mechanism between DAZ and SC. RESULTS The particle size of DAZ-SC composite nanoparticles was （223.7±12.5）nm，and the polydispersity index was 0.274± 0.012. Zeta-potential was －（17.81±1.63）mV（n＝3）. The stability of nano-suspension was good ，the solid properties of DAZ were greatly improved ，and the dissolution rate was significantly increased. SC was statically quenched under the action of DAZ and the secondary structures of SC were changed. The crystallization process of DAZ was controlled under the action of SC ，and the interaction between DAZ and SC was mainly hydrogen bond and van der Waals force. CONCLUSIONS In this study ，DAZ-SC composite nanoparticles are successfully prepared. In the “bottom-up”technology，the interaction between SC and DAZ caused by hydrogen bond and van der Waals force inhibits the growth and agglomeration of drug crystals .
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Organophosphorus pesticides ( OPP) and organophosphorus nerve agents ( OPNAs) are both toxic organophosphorus compounds, which mainly exert toxic effects through irreversible inhibition of acetylcholinesterase ( AChE).This paper takes protein adducts as the research objective, studying the covalent adducts formed by OPP/OPNAs and different target proteins:endogenous scavengers ( butyrylcholinesterase, albumin, transfer-rin) and low-dose toxicity related proteins ( Cytoskeleton pro- tein, neuropathic target esterase, ubiquitin ) .The formation mechanism of protein adducts and the structural characteristics of active sites are reviewed for providing new ideas to confirm the exposure, trace, and accurate treatment and reasonable prevention of OP poisons in the future.
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Objective:To explore the price formation method and price standard in the big data diagnosis-intervention packet.Methods:The expenditure data and income data of 95 medical institutions in Shanghai in 2018 were used for analysis, including 33 municipal hospitals and 62 district hospitals. After using the standardized data of disease score, the medical institutions in the region were divided into four quadrants with the regional average of unit price per index and cost per index as the coordinate axis. The best quadrant of income and cost was found out, namely the high quality range. The geometric center was calculated in the high quality range, and the unit price per index of the geometric center was taken as the cost standard.Results:For the district hospitals, there were 20 hospitals in the first quadrant, 8 in the second quadrant, 24 in the third quadrant and 10 in the fourth quadrant; For the municipal hospitals, there were 7 hospitals in the first quadrant, 5 in the second quadrant, 12 in the third quadrant and 9 in the fourth quadrant. In the third quadrant, the average income and cost of medical institutions were lower than the average of the city, and the income could cover the cost. The third quadrant was the high quality range. The unit price per index of the third quadrant geometric center of district hospitals was 14 115.4 yuan, and that in municipal hospitals was 15 559.1 yuan, which could be used as the corresponding cost standard.Conclusions:The price discovery mechanism based on objective data and high-quality interval geometric center method can remove the impact of unreasonable charges or unreasonable behavior on medical income, and reflect the guidance of the standard price of medical insurance payment.
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This paper, taking the formulation of national drug standards for traditional Chinese medicine (TCM) dispensing granules as a case study, explores the improvement of the formation mechanism of national drug standards, and promotes the reform of streamline administration, delegate powers, and improve regulation and services of national standards management, so as to release the vitality of the research and development of standards of drug manufacturers. After nearly two decades of pilot production of TCM dispensing granules, a large number of researches and discussions have been conducted on the formulation of unified standards of TCM dispensing granules from manufacturing enterprises to national standard administration departments, it was found that this work was difficult on the basis of the original drug standard formation mechanism. The authors tried to improve and innovate the formation mechanism of national drug standards, to provide methods and ideas for the formulation and unification of national standards for TCM dispensing granules, and to provide references for the formulation of other national drug standards.
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Deep vein thrombosis (DVT) is a common clinical complication with diversified causes. The high morbidity, mortality and disability rate have made it become one of the important risk factors affecting human health. DVT has long been considered as blood coagulation disorder, but the pathogenesis is still unclear, and increasing evidence now demonstrate that immune system regulation and inflammatory processes are critically involved in DVT initiation and development. Chinese materia medica for invigorating circulation and removing blood stasis has a unique advantage in the prevention and treatment of DVT. Here, we briefly summarize the factors contributing the formation of deep venous thrombosis, especially the role of immune cells and platelet in DVT. Importantly, we also analyze and forecast the prospect of Chinese medicine with immunomodulatory effects in the prevention and treatment of DVT, hoping to shed new light on future development of more effective treatment for DVT and provide guidance of their clinical applications.
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Catechins are the key components of tea and have a great impact on its quality. Catechins can be oxidized to form a new black tea polyphenols, some of which have better pharmacological effect. However, the formation mechanism of these new polyphenols is still unclear. In this paper, oxidation products coming from catechins and the formation mechanism of the new compounds are reviewed.It is the base of further study on theaflavins, thearubigins and theabrownines.
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The service capabilities and sustainable development of community doctors' first contact are undoubtedly the critical factors to promote the construction of grassroots clinics and tiered health care system.Based on the review of motivation-related concepts and its development, as well as the analysis of the current conditions of community first contact and characteristics of community doctors in China, this paper puts forward and defines the concept and connotation of service motivation for community doctors' first contact by logically summarizing the concept of force in physical sciences ,motivation in service science, Based on analyzing the extrinsic motivations to form community doctors' first contact such as attraction, support, constraint, and stress the intrinsic motivations produced by professional identity, self-efficacy and achievement,as well as the interactions and relationships between them, this paper contructs a formation mechanism of the service motivation for community doctors' first contact, which is visual and intuitive.This paper provides a logical path and basis for scientific governance and upgrade of the service motivation for community doctors's first contact to effectively promote community first contact system in China.
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@#The aim of this study was to prepare albumin nanoparticles by thermal driven self-assembly, and to investigate the formation mechanism, cellular uptake, the kinetics of cellular uptake and intracellular degradation, etc. By measuring the concentrations of thiol, amino and carboxyl groups, the formation mechanism of albumin nanoparticles was revealed. CCK-8 assay was performed to detect the cytotoxicity; inverted fluorescence microscope was used to observe the cellular uptake of the nanoparticles; while the fluorescence resonance energy transfer(FRET)method was applied to investigate the cellular uptake and intracellular degradation kinetics. The drug-loading capacity was investigated using paclitaxel(PTX)as the model drug. The results showed that the albumin nanoparticles produced by thermal driven self-assembly were safe, nontoxic, biodegradable and stabilized by intermolecular disulfide and amide bonds. The drug-loading study indicates that PTX can be highly encapsulated in the nanoparticles. Hence, thermal driven self-assembly method is green and easy to operate, and the albumin nanoparticles can be applied as a new delivery platform for anticancer drugs.
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@#Ocotillol(3)and its epimer(4)have been synthesized from 20(S)-protopanaxatriol ［20(S)-PPT］ via two routes, and their formation mechanism has been speculated. Route 1: Compounds 3 and 4 were obtained from 20(S)-PPT by oxidation with m-CPBA at the yield of 44. 1% and 28. 6%, respectively. Route 2: Compounds 3 and 4 were prepared from 20(S)-PPT by acetylation, oxidation and saponification at the yield of 16. 4% and 16. 2%, respectively. The formation mechanism of compounds 3 and 4 is speculated as below: 1)The chemical environments of both sides of C24(25)double bond in 20(S)-PPT are different due to the existence of intramolecular hydrogen bond, which led to the different oxidation ratio of the two sides, and the different yields of compounds 3 and 4. 2)There is not intramolecular hydrogen bond in acetylated 20(S)-PPT, and the chemical environments of both sides of C24(25)double bond are similar, which resulted in almost equal yields of compounds 3 and 4 synthesized through oxidation with m-CPBA, intramolecular SN2 and saponification.
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In this study, the Pickering emulsions were prepared using medium chain triglycerides (MCT) and α-cyclodextrin (α-CD) and the formation mechanism was studied by means of several physicochemical techniques. The MCT/α-CD microparticles, which stabilized the emulsions, were characterized by the measurement of interfacial tension and the contact angle (θow), powder X ray diffraction (XRD), scanning electron microscope (SEM), high performance liquid chromatography (HPLC), differential interference microscope (DIM), Cryo-scanning electron microscopy (Cryo-SEM). The physical stability of emulsions with different α-CD content in the continuous aqueous phase was investigated by determination of the droplet size and sedimentation rate, combined with the observation of droplet morphologies by the inverted phase contrast microscope. As a result, it was observed that the amphiphilic supramolecule of MCT and α-CD were indeed formed. Furthermore, MCT/α-CD microparticles formed by the aggregation of MCT/α-CD supramolecule absorbed at the oil/water interface, and then forming a membrane structure to stabilize emulsion. In addition, the average θow for the MCT/α-CD microparticles was (46.1±3.4)° which stabilized O/W emulsion. When the content of α-CD was increased in the continuous phase, there were more microparticles formed at the oil/water interface and in the continuous aqueous phase, which resulted in smaller particle size of droplet and higher viscosity of the continuous phase. In summary, the study suggest that α-CD/MCT/water emulsions were of O/W Pickering emulsions and the physical stability was better for emulsions with higher content of α-CD in the continuous phase.
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Microcalcifications are among the most common imaging findings of breast cancer. This article reviews the recent liter-ature regarding the foci of microcalcifications in breast cancer. In particular, we summarize the composition, formation mechanism, and biopsy method of the microcalcifications;the relationship between the foci and clinicopathologic indicators;and the influence of neoad-juvant chemotherapy on the foci.
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In recent years, there is a rapid upward trend of Chinese residents’self-medication. It analyzes the formation mechanism of self-medication from three directions: inheritance mechanism, power mechanism and strengthening mechanism. It explains the cause of rapid rise of self-medication, and provides useful lessons for objective understanding of self-medication.