As a distinctive resource of Chinese civilization， traditional Chinese medicine （TCM） technology transfer faces significant opportunities under the background of digital and intelligent transformation， while also being constrained by unique challenges such as the complexity of its theoretical system， lengthy industrial chains， and multidimensional policy restrictions， resulting in a "high-value-high-threshold" paradox. At present， TCM technology transfer is deeply trapped in a "threefold reluctance" dilemma， i.e.， unwillingness to transfer， inability to transfer， and lack of capacity to transfer. Specifically， the disconnection between scientific research evaluation systems and market demand leads to low conversion rates of research achievements， unclear ownership and compliance risks suppress innovation incentives， and the absence of professional services intensifies supply-demand mismatches. This article systematically analyzes the specific characteristics of TCM technology transfer and proposes a breakthrough pathway centered on full-chain digital and intelligent transformation. By integrating technologies such as intelligent sorting systems， blockchain-based traceability， and AI diagnostic models， the TCM ecosystem spanning "cultivation-production-service" can be reconstructed. In terms of standardization， promoting the progression from "experience-based data conversion" to "data standardization" and further to "intelligent standardization" is advocated to resolve quality control challenges. For example， a "three-no-one-full" certification system can strengthen quality trust. Policy coordination should focus on optimizing mechanisms for the transformation of scientific and technological achievements， while exploring intellectual property securitization and risk-sharing models to stimulate research momentum. In terms of internationalization， reliance on the Belt and Road Initiative platform to promote the export of geo-authentic medicinal material brands and standards is recommended to build a dual-driven model of "technology plus culture". Looking ahead， through the construction of national-level databases， the cultivation of interdisciplinary talent， and the mutual recognition of international standards， a new paradigm of "scientific intelligent manufacturing" can be formed， providing systematic solutions for the modernization of TCM and global health governance.

Objective: To compare the consistency between bioelectrical impedance analysis (BIA) and dual energy X ray absorptiometry (DXA) in measuring body composition among Tibetan children and adolescents and to explore the applicability of BIA in plateau region, so as to provide scientific and convenient body composition measurement support among children and adolescents. Methods: From May to June, 2022, a total of 344 Tibetan children and adolescents aged 6-17 years were selected from Golmud Municipal National Middle School and Changjiangyuan Nationality Primary School in Qinghai Province by cluster sampling method, and their fat mass, fat mass percentage and lean mass were measured by DXA and BIA. The consistency and correlation between the two methods were assessed by using the Wilcoxon rank-sum test, Spearman correlation analysis, intraclass correlation coefficient (ICC), and Bland-Altman analysis. Results: DXA measured fat mass and fat mass percentage were significantly higher than those obtained by BIA (6-12 years old: Z =9.91, 11.28; 13-17 years old: Z =9.02, 10.21), while lean mass and lean mass percentage were significantly lower than BIA results (6-12 years old: Z =-11.60, -11.30; 13-17 years old: Z =-10.77, -10.36) (all P < 0.05 ). The two methods showed strong correlations in fat mass and lean mass (all r >0.80, all ICC >0.90), but exhibited poor agreement in fat mass percentage and lean mass percentage (6-12 years old: Lin s CCC =0.64, 0.41; 13-17 years old: Lin s CCC = 0.79 , 0.35). Bland-Altman analysis showed that the difference between the two methods was negatively correlated with the average value in FM%(6-12 years old: r =-0.75, 13-17 years old: r =-0.79, both P <0.01). Conclusion BIA and DXA show high consistency in measuring body fat mass and lean body mass in Tibetan children and adolescents, although some bias is still present in certain individuals.

This paper outlines the development of artificial intelligence （AI） and its applications in traditional Chinese medicine （TCM） research， and elucidates the roles and advantages of large language models， knowledge graphs， and natural language processing in advancing syndrome identification， prescription generation， and mechanism exploration. Using spleen-stomach diseases as an example， it demonstrates the empowering effects of AI in classical literature mining， precise clinical syndrome differentiation， efficacy and safety prediction， and intelligent education， highlighting an upgraded research paradigm that evolves from data-driven and knowledge-driven approaches to intelligence-driven models. To address challenges related to privacy protection and regulatory compliance in cross-institutional data collaboration， a "trusted federated evidence-based analysis platform for TCM spleen-stomach diseases" is proposed， integrating blockchain-based smart contracts， federated learning， and secure multi-party computation. The deep integration of AI with privacy-preserving computing is reshaping research and clinical practice in TCM spleen-stomach diseases， providing feasible pathways and a technical framework for building a high-quality， trustworthy TCM big-data ecosystem and achieving precision syndrome differentiation.

The initiation of adaptive immune responses relies on the precise recognition and interpretation of antigenic information. In this process, the specific binding of T cell receptors (TCRs) to peptide-major histocompatibility complex (pMHC) molecules represents one of the key molecular events in the initiation of adaptive immune responses. Accordingly, the structural features of TCR-pMHC complexes provide a fundamental basis for dissecting antigen recognition mechanisms and support rational vaccine design, therapeutic target discovery in TCR-based immunotherapy, and TCR identification and optimization. However, experimental determination of TCR-pMHC structures remains costly, time-consuming, and limited in coverage, making computational approaches essential for rapidly obtaining reliable structural information. Computational methods for predicting the structures of TCR-pMHC complexes have advanced rapidly in recent years, driven by progress in deep learning-based modeling frameworks and the increasing availability of structural and sequence resources. Despite these developments, most existing tools do not adequately distinguish the key structural and biophysical differences between MHC class I (MHC-I) and MHC class II (MHC-II) complexes during model construction. As a consequence, their predictive performance differs substantially between class I and class II complexes. In general, structural predictions for class I complexes outperform those for class II complexes. This discrepancy may be related to several fundamental differences between the two systems, including the architecture of the peptide-binding groove, the distribution of peptide lengths, and the properties of peptide flanking residues (PFRs). Compared with MHC-I molecules, MHC-II molecules usually bind longer antigenic peptides, which typically range from 13 to 25 amino acids in length. PFRs at both termini of these peptides participate in regulating the overall conformation of TCR-pMHC class II complexes and exert a pronounced effect on the geometric and physicochemical characteristics of the TCR-pMHC binding interface. Furthermore, within the TCR recognition interface, the complementarity-determining regions (CDRs) consist of segments that differ markedly in conformational behavior. They commonly include regions that are relatively rigid and structurally stable, together with highly flexible segments exhibiting substantial conformational plasticity. These rigidity-flexibility features constitute an essential structural basis enabling TCRs to recognize diverse peptide-MHC ligands and to accommodate conformational heterogeneity at the interface. However, many current modeling tools, in an effort to enforce global conformational stability or reduce structural noise, tend to over-constrain intrinsically flexible regions. Such oversimplification may lead to inappropriate rigidification of flexible CDR loops, resulting in local structural distortions, compromised interface geometry, or even complete modeling failure for specific complexes. Against this background, the review approaches the field from the perspective of computational differences between MHC-I and MHC-II complexes. We first systematically organize and summarize available resources related to TCRs and pMHCs, including structural datasets, sequence databases, prediction tools, and benchmarking studies. We then focus on five representative tools capable of predicting both class I and class II complexes—AlphaFold2, AlphaFold3, TCRmodel2, tFold-TCR, and TCR-pHLA_ModellerS. After excluding structures present in the training sets of these tools, we constructed a benchmark dataset comprising 25 class I and 10 class II TCR-pMHC complexes in the bound state and conducted a systematic evaluation using this dataset. We first employ widely used general evaluation metrics, including All-Atom Root Mean Square Deviation (All-Atom RMSD), Backbone RMSD, Template Modeling score (TM-score), and DockQ, to assess the global conformational accuracy and interface modeling quality of class I and class II complexes. For class II complexes, we propose for the first time a peptide flanking residue deviation index, including the PFRs-Deviation Index (PFRs-DI), N-PFR-Deviation Index (N-PFR-DI), and C-PFR-Deviation Index (C-PFR-DI), to quantitatively characterize conformational deviations in PFRs. In addition, we propose the CDR conformational consistency index (CCC) designed to qualitatively evaluate the ability of prediction tools to capture TCR CDR conformational flexibility. These metrics collectively assess a tool’s ability to model both overall conformation and critical functional regions, thereby addressing the limitations of existing evaluation criteria that overemphasize global structure while inadequately capturing modeling quality in key functional areas. This establishes a unified analytical framework for MHC-I and MHC-II complexes to guide data resource selection, modeling strategy formulation, and evaluation system development. The framework further advances computational modeling and provides crucial support for multi-scale analysis of TCR-pMHC recognition mechanisms and their biological functions.

The initiation of adaptive immune responses relies on the precise recognition and interpretation of antigenic information. In this process, the specific binding of T cell receptors (TCRs) to peptide-major histocompatibility complex (pMHC) molecules represents one of the key molecular events in the initiation of adaptive immune responses. Accordingly, the structural features of TCR-pMHC complexes provide a fundamental basis for dissecting antigen recognition mechanisms and support rational vaccine design, therapeutic target discovery in TCR-based immunotherapy, and TCR identification and optimization. However, experimental determination of TCR-pMHC structures remains costly, time-consuming, and limited in coverage, making computational approaches essential for rapidly obtaining reliable structural information. Computational methods for predicting the structures of TCR-pMHC complexes have advanced rapidly in recent years, driven by progress in deep learning-based modeling frameworks and the increasing availability of structural and sequence resources. Despite these developments, most existing tools do not adequately distinguish the key structural and biophysical differences between MHC class I (MHC-I) and MHC class II (MHC-II) complexes during model construction. As a consequence, their predictive performance differs substantially between class I and class II complexes. In general, structural predictions for class I complexes outperform those for class II complexes. This discrepancy may be related to several fundamental differences between the two systems, including the architecture of the peptide-binding groove, the distribution of peptide lengths, and the properties of peptide flanking residues (PFRs). Compared with MHC-I molecules, MHC-II molecules usually bind longer antigenic peptides, which typically range from 13 to 25 amino acids in length. PFRs at both termini of these peptides participate in regulating the overall conformation of TCR-pMHC class II complexes and exert a pronounced effect on the geometric and physicochemical characteristics of the TCR-pMHC binding interface. Furthermore, within the TCR recognition interface, the complementarity-determining regions (CDRs) consist of segments that differ markedly in conformational behavior. They commonly include regions that are relatively rigid and structurally stable, together with highly flexible segments exhibiting substantial conformational plasticity. These rigidity-flexibility features constitute an essential structural basis enabling TCRs to recognize diverse peptide-MHC ligands and to accommodate conformational heterogeneity at the interface. However, many current modeling tools, in an effort to enforce global conformational stability or reduce structural noise, tend to over-constrain intrinsically flexible regions. Such oversimplification may lead to inappropriate rigidification of flexible CDR loops, resulting in local structural distortions, compromised interface geometry, or even complete modeling failure for specific complexes. Against this background, the review approaches the field from the perspective of computational differences between MHC-I and MHC-II complexes. We first systematically organize and summarize available resources related to TCRs and pMHCs, including structural datasets, sequence databases, prediction tools, and benchmarking studies. We then focus on five representative tools capable of predicting both class I and class II complexes—AlphaFold2, AlphaFold3, TCRmodel2, tFold-TCR, and TCR-pHLA_ModellerS. After excluding structures present in the training sets of these tools, we constructed a benchmark dataset comprising 25 class I and 10 class II TCR-pMHC complexes in the bound state and conducted a systematic evaluation using this dataset. We first employ widely used general evaluation metrics, including All-Atom Root Mean Square Deviation (All-Atom RMSD), Backbone RMSD, Template Modeling score (TM-score), and DockQ, to assess the global conformational accuracy and interface modeling quality of class I and class II complexes. For class II complexes, we propose for the first time a peptide flanking residue deviation index, including the PFRs-Deviation Index (PFRs-DI), N-PFR-Deviation Index (N-PFR-DI), and C-PFR-Deviation Index (C-PFR-DI), to quantitatively characterize conformational deviations in PFRs. In addition, we propose the CDR conformational consistency index (CCC) designed to qualitatively evaluate the ability of prediction tools to capture TCR CDR conformational flexibility. These metrics collectively assess a tool’s ability to model both overall conformation and critical functional regions, thereby addressing the limitations of existing evaluation criteria that overemphasize global structure while inadequately capturing modeling quality in key functional areas. This establishes a unified analytical framework for MHC-I and MHC-II complexes to guide data resource selection, modeling strategy formulation, and evaluation system development. The framework further advances computational modeling and provides crucial support for multi-scale analysis of TCR-pMHC recognition mechanisms and their biological functions.

Plant-derived extracellular vesicles (PDEVs) are nanoscale extracellular vesicles secreted by plant cells, characterized by a lipid bilayer structure. These vesicles carry a variety of bioactive molecules, including proteins, nucleic acids, and lipids, and play essential roles in intercellular communication and physiological regulation in plants. Compared to animal-derived extracellular vesicles, PDEVs offer several advantages, such as a broad range of sources, high biocompatibility, low immunogenicity, and low production costs. Furthermore, PDEVs have demonstrated remarkable potential as natural nanocarriers for drug delivery, due to their ability to efficiently traverse biological barriers, such as the blood-brain barrier, making them promising candidates for drug delivery systems. This review systematically elaborates on the complex composition of PDEVs, which consists of lipids, proteins, and nucleic acids, the typical structural characteristics of their lipid bilayers ranging from 30 to 150 nm, and their versatile loading capabilities as drug carriers, efficiently encapsulating various types of therapeutic agents such as hydrophilic small molecules, hydrophobic drugs, nucleic acids, and proteins. We systematically summarize the recent advancements in strategies for enhancing the loading efficiency of PDEVs, which include methods such as co-incubation, ultrasound-assisted loading, electroporation, freeze-thaw cycles, and microfluidic technology. These techniques are evaluated based on their underlying principles, suitable drug types, and their respective advantages. In addition to loading strategies, we focus on the engineered approaches to achieve targeted delivery using PDEVs, such as genetic engineering modifications, chemical ligand conjugation, membrane fusion technology, and polyethylene glycol (PEG) modification. We discuss the mechanisms of these strategies in enhancing targeting efficiency, prolonging in vivo circulation time, and improving therapeutic efficacy. Further, this review highlights the application of PDEVs in various disease models, including tumor, skin inflammation, metabolic disorders, and neurodegenerative diseases, showcasing their therapeutic potential as multifunctional delivery platforms. The ability of PDEVs to encapsulate diverse therapeutic agents and target specific tissues or cells opens up new avenues for the treatment of complex diseases, offering advantages over conventional drug delivery systems. However, despite the promising applications of PDEVs, several challenges remain in their development and clinical translation. These challenges include variability in source materials, standardization of preparation processes, quality control, scalability of production, and the need for clinical validation. To overcome these obstacles, the integration of advanced technologies such as artificial intelligence-assisted design and multi-omics analysis is proposed as a way to facilitate the precise development of PDEVs. These emerging technologies hold the potential to further enhance the precision and effectiveness of plant-based drug delivery systems, ultimately advancing the field of precision medicine. In conclusion, the use of PDEVs as a platform for drug delivery represents a promising area of research with the potential to revolutionize therapeutic strategies. Their ability to encapsulate and deliver a wide variety of bioactive molecules, along with their inherent advantages in biocompatibility and versatility, makes them a valuable tool in the development of more efficient and targeted therapeutic interventions. Continued research and innovation in this field will pave the way for the clinical implementation of PDEVs in the treatment of various diseases, offering new hope for more effective and sustainable therapeutic options.

Objective To study the pathogenic bacteria infection in hospitalized diabetic foot patients in the Third People's Hospital of Yunnan Province and its correlation with different Wagner grades,to understand the the characteristics of pathogenic bacteria and related risk factors in hospitalized diabetic foot patients in the Third People's Hospital of Yunnan Province,and to further provide theoretical guidance for anti-infection treatment of these patients.Methods A retrospective analysis was conducted on the demographic data,severity of foot ulcers,and related laboratory test results of 536 patients with diabetic foot who were detected to have bacterial infection in the Third People's Hospital of Yunnan Province from January 2019 to January 2023.Results Among the 536 diabetic foot patients,pathogenic bacteria were cultured from 268 cases(50.0%)of Gram-positive bacterial infections,214 cases(39.9%)of gram-negative bacterial infections,2 cases(0.4%)of fungal infections,and 52 cases(9.7%)of mixed bacterial infections.The main pathogens among gram-positive bacteria were Staphylococcus aureus,Staphylococcus epidermidis and Enterococcus faecalis.for Gram-negative bacteria,the main pathogens were Escherichia coli,Enterobacter cloacae and Klebsiella pneumoniae.There were 31 cases of multi-drug resistant bacteria,and the multi-drug resistance rate was(5.78%).Among Gram-positive bacteria,all multidrug-resistant strains were Staphylococcus aureus,while among Gram-negative bacteria,the multi-drug resistant strains included Acinetobacter baumannii(1 case),Klebsiella pneumoniae(2 cases),Proteus common(2 cases),Pseudomonas aeruginosa(5 cases),Proteus mirabilis(1 case)and Enterobacter cloacae(1 case).The 536 patients were divided into Wagner grade 1 and 2 groups(78 cases),Wagner grade 3 group(274 cases),and Wagner grade 4 and 5 groups(184 cases).There were 73 cases of single bacterial infections and 5 cases of mixed bacterial infections in Wagner grade 1 and 2 group,including 51 cases(65.4%)of gram-positive bacteria,21 cases(26.9%)of gram-negative bacteria and 1 case(1.3%)of fungi.There were 248 cases of single bacterial infections and 26 cases of mixed bacterial infections in Wagner3 group,with 144 cases(52.6%)of gram-positive bacteria,103 cases(37.6%)of gram-negative bacteria,and 1 case(0.4%)with fungi.In the Wagner grade 4 and 5 groups,there were 163 cases of single bacterial infections and 21 cases of mixed bacterial infection,with 73 strains(39.7%)of gram-positive bacteria,90 strains(48.9%)of gram-negative bacteria and 0 strain(0%)of fungi.The predominant infectious pathogens in Wagner grades 1,2 and 3 were gram-positive bacteria,while those in Wagner grades 4 and 5 patients were mainly gram-negative bacteria.There were statistically significant differences in white blood cell counts,neutrophil percentage,bacterial classification,length of hospital stay,erythrocyte sedimentation rate and albumin levels among diabetic foot patients with different Wagner grades(P<0.01).With the increase of Wagner grade,patients had higher white blood cell counts and hypersensitive C-reactive protein levels,longer hospital stays,and lower albumin levels;however,there were no statistically significant differences in age,sex,duration of diabetes,smoking history,alcohol consumption history and history of hypertension(P>0.05).Conclusion The bacterial infection situation in patients with diabetic foot ulcers is related to different Wagner grades.The higher the Wagner grades,the greater the likelihood of infection with gram-negative bacteria.Antibiotics can be reasonably selected according to the Wagner grades of patients upon admission,actively controlling infection,while also enhancing,shortening hospital stays,and reducing amputation rates,thereby improving the prognosis of diabetic foot patients.

Objective To analyze the bacterial distribution characteristics,drug resistance characteristics and related risk factors of multidrug-resistant organisms(MDRO)in patients with diabetic foot infection(DFI)in some areas of Yunnan Province to provide empirical reference for clinical treatment.Methods Clinical data of 300 DFI patients admitted to the Department of Endocrinology of the Third People's Hospital of Yunnan Province from January 2019 to December 2023 were collected.Based on the results of drug sensitivity tests and matching of basic data,patients were divided into the MDRO group(n=60)and the non-MDRO group(n=240).A retrospective analysis was conducted on the distribution of pathogenic bacteria,drug resistance characteristics of MDRO and risk factors for MDRO infection in DFI patients.Results In 60 patients with MDRO infections,62 strains of MDRO were cultured,with 58 strains from single MDRO infections and 4 strains from mixed MDRO infections.Of the 60 patients,2 were cultured for 2 types of MDRO.Among the strains,there were 45 gram-positive bacteria(72.58％)which were all Staphylococcus aureus,17 strains of gram-negative bacteria(27.42％)mainly including Pseudomonas aeruginosa,Enterobacter cloacae and Klebsiella pneumoniae.Among common MDRO,Staphylococcus aureus showed complete resistance to penicillin G and oxacillin(100％),with high resistance to erythromycin and clindamycin(＞80％),but no resistance to tigacycline vancomycin was observed.The resistance of Klebsiella pneumoniae and Enterobacter cloacae to cephalosporin antibiotics was obvious,and the resistance rate to imipenem and amikacin was low.Pseudomonas aeruginosa was 100％resistant to ticacillin/clavulanate potassium,imipenem,tigacycline and cotrimoxazole,but showed no resistance to cefepime,ciprofloxacin,gentamicin and amikacin.There were statistically significant differences between the two groups in regional distribution,duration of diabetic foot,lower extremity arterial disease,venous plasma glucose levels and glycosylated hemoglobin(P＜0.05).Binary Logistic regression analysis showed that region and duration of diabetic foot disease were independent risk factors for MDRO infection in DFI patients(P＜0.05).Conclusion In some areas of Yunnan Province,the distribution of MDRO in DFI patients is mainly gram-positive bacteria,with varying antibiotic sensitivities among different pathogens.Multiple factors lead to MDRO infections in DFI patients,which assists clinical practitioners in early identification of high-risk DFI patients with MDRO infections and provide empirical reference for clinical treatment.

Gene synthesis is an enabling technology that supports the development of synthetic biology. The existing approaches for de novo gene synthesis generally have tedious operation, low efficiency, high error rates, and limited product lengths, being difficult to support the huge demand of synthetic biology. The assembly and error correction are the keys in gene synthesis. This study first designed the oligonucleotide sequences by reasonably splitting the virus genome of approximately 10 kb by balancing the parameters of sequence design software ability, PCR amplification ability, and assembly enzyme assembly ability. Then, two-step PCR was performed with high-fidelity polymerase to complete the de novo synthesis of 3.0 kb DNA fragments, and error correction reactions were performed with T7 endonuclease Ⅰ for the products from different stages of PCR. Finally, the virus genome was assembled by 3.0 kb DNA fragments from de novo synthesis and error correction and then sequenced. The experimental results showed that the proposed method successfully produced the DNA fragment of about 10 kb and reduced the probability of large fragment mutations during the assembly process, with the lowest error rate reaching 0.36 errors/kb. In summary, this study developed an efficient de novo method for synthesizing a viral genome of about 10 kb with T7 endonuclease Ⅰ-mediated error correction. This method enabled the synthesis of a 10 kb viral genome in one day and the correct plasmid of the viral genome in five days. This study optimized the de novo gene synthesis process, reduced the error rate, simplified the synthesis and assembly steps, and reduced the cost of viral genome assembly.
Genome, Viral/genetics* ; Polymerase Chain Reaction/methods* ; DNA, Viral/genetics* ; Bacteriophage T7/enzymology* ; Synthetic Biology/methods*

The study aims to explore the methods for preparing nanocomplexes of Prussian blue nanoparticles (PBNPs) with UNO peptide (UNO-PBNPs) and the functions of the nanocomplexes targeting M2-type macrophages in vitro. PBNPs were prepared by the hydrothermal synthesis method. Subsequently, the peptide UNO (CSPGAKVRC) targeting the mannose receptor was modified on their surface by a heterobifunctional coupling approach. The morphological characteristics of nanoparticles were observed by scanning and transmission electron microscopy. Additionally, their particle size, Zeta potential, and dispersion stability were assessed. The structural characteristics of nanoparticles were analyzed by X-ray diffraction and other techniques. The biological safety of the nanoparticles was evaluated by the CCK-8 assay and hemolysis experiments. Moreover, the targeting performance of UNO-PBNPs towards M2-type macrophages was assessed in vitro. The results showed that the synthesized UNO-PBNPs exhibited uniform cubic morphology, with an average particle size of (202.00±4.21) nm. They were negative charged, well dispersed, and stable. At concentrations ≤ 200 μg/mL, the synthesized UNO-PBNPs led to the hemolysis rate below 5%, demonstrating excellent biocompatibility. The laser confocal imaging results showed that after co-incubation with M2-type macrophages, the FITC-labeled UNO-PBNPs were effectively accumulated in the cells, presenting a distinct fluorescence signal. Quantitative analysis by flow cytometry showed that the intracellular mean fluorescence intensity (6 019.00±346.04) of UNO-PBNPs was higher than that (4 054.00±379.14) of unmodified PBNPs (P < 0.001). In summary, the UNO-PBNPs prepared in this study exhibited a targeting effect on M2-type macrophages, providing a potential method for targeted delivery of PBNPs in the tumor microenvironment and laying a foundation for the remodeling of the tumor immunosuppressive microenvironment.
Ferrocyanides/chemistry* ; Nanoparticles/chemistry* ; Macrophages/drug effects* ; Peptides/chemistry* ; Particle Size ; Animals ; Mannose Receptor ; Mice ; Lectins, C-Type ; Mannose-Binding Lectins ; Receptors, Cell Surface