Although global brain science research has progressed rapidly in recent decades, several fundamental questions in neuroscience remain unresolved. In particular, the physical mechanism underlying neural signal transmission remains controversial, and the carriers responsible for neural information storage and retrieval have not yet been fully clarified. These unresolved issues motivate us to re-examine the processes of neural information generation, transmission, integration, storage, and retrieval from multiple perspectives. A key observation is that neural electromagnetic activities are closely associated with time. Their duration, temporal structure, and dynamic evolution play crucial roles in neural information processing. In this work, we analyze neural electromagnetic activities from the perspective of temporal scales (referred to here as the “time course”). By reviewing and integrating findings from previous studies, we examine the characteristic time requirements and dynamic features of neural processes occurring at different stages of information processing. These stages include neural signal generation, signal transmission along axons, synaptic integration, synaptic plasticity, and memory formation and retrieval. Based on this temporal analysis, we outline a framework describing neural electromagnetic activities across a wide range of time scales, spanning from microseconds to minutes, hours, or even longer periods associated with long-term memory, which suggests that neural information processing involves multiple physical processes operating at different time levels. Rapid electromagnetic events may occur on microsecond scales, whereas electrophysiological phenomena such as action potentials typically last on the order of milliseconds. Longer time scales are associated with synaptic plasticity and memory-related processes. From this perspective, we propose that the physical carrier of neural information may be transient electromagnetic pulses with durations on the microsecond scale. In this framework, action potentials can be interpreted as the macroscopic electrophysiological manifestation of underlying electromagnetic processes triggered by ionic currents across neuronal membranes. Rather than being the fundamental neural signal itself, the action potential may represent a measurable membrane-level response associated with the successful activation of these electromagnetic events. Moreover, we discuss a possible mechanism for long-term memory storage. Considering the apparent temporal contradiction between the millisecond-scale excitation of neurons and the long-term persistence of memories, we believe that long-term memory information may be stored within neural network topologies formed by electrical synapse coupling. Such structures, referred to as electrically coupled memory networks (ECMNs), may enable neurons within the same network to respond rapidly and synchronously to stimuli, thereby facilitating efficient memory retrieval. Overall, this study emphasizes the importance of considering the temporal organization of neural electromagnetic activities when interpreting neural signaling mechanisms. It may provide new insights into the physical nature of neural information carriers and the mechanisms of memory storage and retrieval. Furthermore, highlighting the potential role of electromagnetic interactions in neural activity may contribute to the development of new theoretical frameworks and experimental approaches in neuroscience. Such perspectives may also offer valuable references for future research on neural coding, brain function mechanisms, and neuromodulation technologies.

ObjectiveTo genotype the specimens from hand-foot-and-mouth disease (HFMD) cases in Dehong Prefecture, Yunnan Province in 2023 by gene sequencing, and to analyze the genetic characteristics of Coxsackievirus A4 (CVA4), CVA6, CVA10, CVA16 and enterovirus A71 (EV-A71), so as to clarify the serotypes of enteroviruses causing endemic HFMD and the genotype composition of CVA4, CVA6, CVA10, CVA16 and EV-A71 prevalent in HFMD, and to provide baseline genotype data for monitoring the dynamic changes of the five virus genotypes. MethodsStool specimens from HFMD cases in Dehong Prefecture in 2023 that tested positive for EV-A71, CVA16 and other enteroviruses by real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) were first subjected to gene sequencing and typing of the VP4/VP2 junction region to determine the viral types. Subsequently, the complete VP1 gene of each virus was amplified in two segments using group-specific VP1 gene primers corresponding to enterovirus groups (i.e., enterovirus group A, B, and C) and sequenced (group A virus: primers 486/488 and 487/489, group B virus: primers 490/492 and 491/493, group C virus: primers 494/496 and 495/497). The representative reference sequences of VP1 genes for CVA4, CVA6, CVA10, CVA16 and EV-A71 were downloaded from the literature, and the VP1 gene phylogenetic tree was constructed using MEGA 6.0 software for genetic characterization. ResultsA total of 256 stool specimens were collected from HFMD cases in Dehong Prefecture in 2023, of which 94 tested positive for nucleic acid by RT-qPCR, yielding a positive rate of 36.72%. Of the 94 positive specimens, 83 were identified as group A viruses, and were classified into 5 serotypes (17 strains of CVA4, 3 of CVA6, 6 of CVA10, 49 of CVA16, and 8 of EV-A71). Nine strains were group B viruses, comprising 2 serotypes: 2 strains of echovirus type 3 (E3) and 7 strains of Coxsackievirus B type 5 (CVB5). The remaining 2 strains were group C viruses, both identified as poliovirus type 3 (PV3). Genetic analyses of the VP1 region showed that all 17 CVA4 strains were identified as subgenotype C2, all 3 CVA6 strains as subgenotype D3a, all 6 CVA10 strains as genotype C. Among the 49 CVA16 strains, 46 were identified as subgenotype B1a and 3 as subgenotype B1b, and all 8 EV-A71 strains were identified as subgenotype C4a. ConclusionIn 2023, group A viruses dominated the pathogenic spectrum of HFMD in Dehong Prefecture. Among them, CVA16 had the highest positivity rate. Genetic characteristic analyses showed that CVA4, CVA6, CVA10 and EV-A71 were each composed of a single genotype (subgenotype), while CVA16 was composed of two subgenotypes (B1a and B1b), with B1a being the predominant one. It is recommended that molecular epidemiological surveillance of HFMD pathogens, particularly group A viruses, be continuously strengthened in Dehong Prefecture.

Objective:To analyze the impact of different intrauterine intervention methods and types of complications on fetal prognosis in cases of giant placental chorioangioma (CA), and determine the indications for various treatment methods by analyzing cases of adverse outcomes.Methods:Relevant articles were retrieved from China National Knowledge Infrastructure, VIP Database, Wanfang Database, and Yiigle using the keywords "placental chorioangioma" and "fetal edema" or "anemia" or "cardiomegaly" or "polyhydramnios," and from PubMed, Embase, and UpToDate databases using the keywords "placental chorionic angioma or chorioangioma" and "fetal edema" or "anemia" or "polyhydramnios" or "hyperdynamic circulation" up to June 30th 2023. The size of the angiomas, fetal complications, intrauterine intervention methods, gestational weeks at intervention, and pregnancy outcomes were analyzed. Fetal and neonatal deaths were defined as adverse outcomes. Statistical analysis was performed using an independent sample t-test, rank-sum test, or Chi-square test (continuity correction Chi-square test or Pearson Chi-square test). Results:(1) A total of 582 articles were retrieved, and 51 articles were finally included, comprising 65 cases. Based on the intrauterine intervention methods, these cases were divided into the symptomatic treatment group (17 cases) and the etiological treatment group (48 cases). There were no statistically significant differences between the two groups in the maximum diameter of the angiomas, the gestational weeks at intervention, or the gestational weeks at delivery. (2) The incidence of adverse outcomes was 3/17 in the symptomatic treatment group and 27.1% (13/48) in the etiological treatment group, with no statistically significant difference. In the etiological treatment group, the incidence of adverse outcomes in cases with fetal edema was 45.4% (10/22), which was significantly higher than the 11.5% (3/26) in cases without fetal edema, and the difference was statistically significant ( χ 2=6.94, P=0.008). (3) An analysis of 13 cases with adverse outcomes revealed that nine cases had highly vascularized chorioangiomas and/or blood supply vessels located close to the umbilical cord insertion point on the placenta, and nine were complicated by fetal edema. The incidence of adverse outcomes for fetoscopic laser coagulation/bipolar coagulation, radiofrequency or microwave ablation, bioglue embolization, anhydrous alcohol ablation, and microcoil embolization were 4/19, 3/4, 1/8, 2/9, and 3/6, respectively. Conclusions:Intrauterine treatment of CA should be individualized. Bioglue embolization may be the first-line treatment; Fetoscopic laser coagulation can be applied to cases where the blood supply vessels are small and superficial;Interstitial laser ablation and radiofrequency ablation can be used for branch-type CA when the main blood supply vessels are located within the hemangioma; Anhydrous alcohol ablation is contraindicated due to its risk of fetal circulation entry; Microcoil embolization has the risk of incomplete occlusion, which should be used with caution.

Objective To summarize the changing prevalence of carbapenem resistance in Enterobacterales based on the data of CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021 for improving antimicrobial treatment in clinical practice.Methods Antimicrobial susceptibility testing was performed using a commercial automated susceptibility testing system according to the unified CHINET protocol.The results were interpreted according to the breakpoints of the Clinical & Laboratory Standards Institute(CLSI)M100 31st ed in 2021.Results Over the seven-year period(2015-2021),the overall prevalence of carbapenem-resistant Enterobacterales(CRE)was 9.43％(62 342/661 235).The prevalence of CRE strains in Klebsiella pneumoniae,Citrobacter freundii,and Enterobacter cloacae was 22.38％,9.73％,and 8.47％,respectively.The prevalence of CRE strains in Escherichia coli was 1.99％.A few CRE strains were also identified in Salmonella and Shigella.The CRE strains were mainly isolated from respiratory specimens(44.23±2.80)％,followed by blood(20.88±3.40)％and urine(18.40±3.45)％.Intensive care units(ICUs)were the major source of the CRE strains(27.43±5.20)％.CRE strains were resistant to all the β-lactam antibiotics tested and most non-β-lactam antimicrobial agents.The CRE strains were relatively susceptible to tigecycline and polymyxins with low resistance rates.Conclusions The prevalence of CRE strains was increasing from 2015 to 2021.CRE strains were highly resistant to most of the antibacterial drugs used in clinical practice.Clinicians should prescribe antimicrobial agents rationally.Hospitals should strengthen antibiotic stewardship in key clinical settings such as ICUs,and take effective infection control measures to curb CRE outbreak and epidemic in hospitals.

Objective To characterize the changing species distribution and antibiotic resistance profiles of respiratory isolates in hospitals participating in the CHINET Antimicrobial Resistance Surveillance Program from 2015 to 2021.Methods Commercial automated antimicrobial susceptibility testing systems and disk diffusion method were used to test the susceptibility of respiratory bacterial isolates to antimicrobial agents following the standardized technical protocol established by the CHINET program.Results A total of 589 746 respiratory isolates were collected from 2015 to 2021.Overall,82.6％of the isolates were Gram-negative bacteria and 17.4％were Gram-positive bacteria.The bacterial isolates from outpatients and inpatients accounted for(6.0±0.9)％and(94.0±0.1)％,respectively.The top microorganisms were Klebsiella spp.,Acinetobacter spp.,Pseudomonas aeruginosa,Staphylococcus aureus,Haemophilus spp.,Stenotrophomonas maltophilia,Escherichia coli,and Streptococcus pneumoniae.Each microorganism was isolated from significantly more males than from females(P＜0.05).The overall prevalence of methicillin-resistant S.aureus(MRSA)was 39.9％.The prevalence of penicillin-resistant S.pneumoniae was 1.4％.The prevalence of extended-spectrum β-lactamase(ESBL)-producing E.coli and K.pneumoniae was 67.8％and 41.3％,respectively.The overall prevalence of carbapenem-resistant E.coli,K.pneumoniae,Enterobacter cloacae,Pseudomonas aeruginosa,and Acinetobacter baumannii was 3.7％,20.8％,9.4％,29.8％,and 73.3％,respectively.The prevalence of β-lactamase was 96.1％in Moraxella catarrhalis and 60.0％in Haemophilus influenzae.The H.influenzae isolates from children(＜18 years)showed significantly higher resistance rates to β-lactam antibiotics than the isolates from adults(P＜0.05).Conclusions Gram-negative bacteria are still predominant in respiratory isolates associated with serious antibiotic resistance.Antimicrobial resistance surveillance should be strengthened in clinical practice to support accurate etiological diagnosis and appropriate antimicrobial therapy based on antimicrobial susceptibility testing results.

Objective:To report the nationwide surveillance results of pathogenic profiles and antimicrobial resistance patterns of Gram-positive bloodstream infections in China in 2023.Methods:The clinical isolates of Gram-posttive bacteria from blood cultures were collected in member hospitals of National Bloodstream Infection Bacterial Resistant Investigation Collaborative System（BRICS）during January to December 2023. Antimicrobial susceptibility testing was performed using the dilution method recommended by the Clinical and Laboratory Standards Institute（CLSI）. Statistical analyses were conducted using WHONET 5.6 and SPSS 25.0 software.Results:A total of 4 385 Gram-positive bacterial isolates were obtained from 60 participating center. The top five pathogens were Staphylococcus aureus（ n=1 544，35.2%），coagulase-negative Staphylococci（ n=1 441，32.9%）， Enterococcus faecium（ n=574，13.1%）， Enterococcus faecalis（ n=385，8.8%），and α-hemolytic Streptococci（ n=187，4.3%）. The prevalence of methicillin-resistant Staphylococcus aureus（MRSA）and methicillin-resistant coagulase-negative Staphylococci（MRCNS）was 26.2%（405/1 544）and 69.8%（1 006/1 441），respectively. Notably，all Staphylococci remained susceptible to glycopeptide or daptomycin. Staphylococcus aureus demonstrated excellent susceptibility（>97.0%）to cephalobiol，rifampicin，trimethoprim-sulfamethoxazole，linezolid，minocycline，tigecycline，and eravacycline. No Enterococcus exhibiting resistance to linezolid were detected. Glycopeptide resistance was uncommon but more frequent in Enterococcus faecium（resistance to vancomycin and teicoplanin：both 1.7%）compared to Enterococcus faecalis（both 0.3%）. The detection rates of MRSA and MRCNS exhibited significant regional variations across the country（ χ2=17.674 and 148.650，respectively，both P<0.001）. No vancomycin-resistant Enterococci were detected in central China. Institutional comparison demonstrated higher prevalence of MRSA（ χ2=14.111， P<0.001）and MRCNS（ χ2=4.828， P=0.028）in provincial hospitals than that in municipal hospitals. Socioeconomic analysis identified elevated detection rates of both MRSA（ χ2=18.986， P<0.001）and MRCNS（ χ2=4.477， P=0.034）in less developed regions（per capita GDP

Objective:To report the results of bacterial resistant investigation collaborative system（BRICS）on the distribution and antimicrobial resistance profile of clinical Gram-negative bacteria isolates from bloodstream infections in China in 2023，and provide reference for clinical tretment of bloodstream infections and prevention and control of bacterial resistance.Methods:The clinical isolates of Gram-negative bacteria from blood cultures in member hospitals of BRICS were collected during January 2023 to December 2023. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical and Laboratory Standards Institute（CLSI）. WHONET 5.6 and SPSS 25.0 were used to analyze the data.Results:During the study period，11 492 strains of Gram-negative bacteria were collected from 60 hospitals，of which 10 098（87.9%）were Enterobacterales and 1 394（12.1%）were non-fermentative bacteria. The top 5 bacterial species were Escherichia coli（50.0%）， Klebsiella pneumoniae（26.1%）， Pseudomonas aeruginosa（5.1%）， Acinetobacter baumannii complex（5.0%）and Enterobacter cloacae complex（4.1%）. The ESBL-producing rates in Escherichia coli， Klebsiella pneumoniae and Proteus mirablilis were 46.8%（2 685/5 741），18.3%（549/2 999）and 44.0%（77/175），respectively. The prevalence of carbapenem-resistant Escherichia coli（CREC）and carbapenem-resistant Klebsiella pneumoniae（CRKP）were 1.3%（76/5 741）and 15.0%（450/2 999）；32.9%（25/76）and 78.0%（351/450）of CREC and CRKP were sensitive to ceftazidime/avibactam combination，respectively. 94.7%（72/76）and 90.2%（406/450）of CREC and CRKP were sensitive to aztreonam/avibactam combination. Furthermore，57.9%（44/76）and 79.1%（356/450）were sensitive to imipenem/relebactam combination. The prevalence of carbapenem-resistant Acinetobacter baumannii（CRAB）complex was 64.6%（370/573），while more than 80.0% of CRAB complex was sensitive to tigecycline，eravacycline and polymyxin B. The prevalence of carbapenem-resistant Pseudomonas aeruginosa（CRPA）was 17.0%（99/581）. There were differences in the composition ratio of Gram-negative bacteria in bloodstream infections and the prevalence of important Gram-negative bacteria resistance among different regions in China，with statistically significant differences in the prevalence of CREC，CRKP，CRPA and CRAB complex（ χ2=10.6，28.6，10.8 and 19.3， P<0.05）. The prevalence of ESBL-producing Escherichia coli， CREC，CRAB complex and CRKP were higher in provincial hospitals than those in municipal hospitals（ χ2=12.5，9.8，12.7 and 57.8，all P<0.01）. Conclusions:Gram-negative bacteria are the main pathogens causing bloodstream infections in China，and Escherichia coli is ranked in the top，while the trend of Klebsiella pneumoniae increases continuously with time. CRKP infection shows a slow upward trend，CREC infecton maintains a low prevalence level，and CRAB complex infection continues to exhibit a high prevalence rate. The composition and resistance patterns of pathogens causing bloodstream infections vary to some extent across different regions and levels of hospitals in China.

Objective:To summarize the clinical characteristics of focal cerebral arteriopathy (FCA) in children, and to analyze its influencing factor of prognosis.Methods:A retrospective cohort study was conducted. Clinical data from 40 children with FCA who were hospitalized at the Department of Neurology, Beijing Children′s Hospital, Capital Medical University, from September 2015 to August 2024 were collected. A centralized follow-up was conducted in October 2024 via outpatient clinics or the internet. The pediatric stroke outcome measure (PSOM) was used to evaluate their outcomes. Based on the PSOM, the children were further divided into a group with normal neurological function and another group with abnormal neurological function. Differences between groups were analyzed using the Mann-Whitney U test and Fisher exact test. Univariate Logistic regression analysis was performed to identify the influencing factors for neurological outcomes in children with FCA. Results:A total of 40 children were included, with 20 males and 20 females, and the onset age of 9.2 (6.8, 12.5) years. Among them, 12 cases (30%) had a history of varicella within 1 year before onset. There were 23 cases (58%) presenting with transient ischemic attack (TIA) or recurrent fluctuating symptoms of onset, while 3 cases (8%) developed progressive stroke within the first month of onset. The M1 segment of the middle cerebral artery was the most commonly affected vascular site, with a total of 16 cases (40%). Arterial occlusion occurred in 8 cases (20%). Lumbar puncture was completed in 36 children, and white blood cell counts in cerebrospinal fluid was increased in 6 cases. All 23 patients who completed magnetic resonance vessel wall imaging (VWI) showed circular enhancement of the arterial wall. A total of 28 patients (70%) received antiplatelet or anticoagulation therapy, and 16 patients (40%) received hormone therapy. At admission, the pediatric National Institute of Health Stroke Scale (PedNIHSS) score was 6.0 (2.0, 8.8) points, which decreased to 0.5 (0, 3.0) points at discharge. The follow-up duration was 1.6 (0.8, 4.9) years, with 1 case lost to follow-up. There was 1 case presenting with recurrence course manifesting as TIA. Among the 39 cases who completed the follow-up, 23 cases (59%) were assessed as neurologically normal by PSOM, while 16 cases (41%) were assessed as neurologically abnormal. Among the 29 cases who completed the imaging review, magnetic resonance angiography (MRA) review in 23 cases indicated stability or improvement in the original arterial stenosis, with 6 cases experiencing transient worsening of arterial stenosis early in the disease course (within 2 months), which later improved. Arterial stenosis progression occurred in 6 cases at the final review of 29 cases who completed the imaging review, with 1 case developing progressive cerebral arteriopathy. The proportion of patients with headache, altered consciousness, and aphasia in the abnormal neurological function group, as well as the PedNISS scores at admission and discharge, were all higher than those in the normal neurological function group (all P<0.05). Univariate Logistic regression analysis revealed that only a PedNISS score>6 points at onset was an influencing factor for abnormal neurological function ( OR=20.58, 95% CI 3.93-107.70, P<0.001). Conclusions:Childhood FCA often presents with fluctuating onset, and the proximal segment of the middle cerebral artery is frequently affected. Progression of arterial stenosis is common within 2 months of the disease course, but clinical progression and new ischemic lesions are uncommon. Most patients have a favorable long-term prognosis. PedNIHSS score>6 points at admission is related to abnormal neurological function outcomes.

Objective To explore the value of coronary CT angiography(CCTA)combined with serum in-terleukin(IL)-12p70,protein C(PC)and protein S(PS)in the diagnosis of coronary artery stenosis in coro-nary heart disease.Methods A total of 186 patients with coronary artery disease admitted to Wujin Hospital Affiliated to Jiangsu University(Changzhou Wujin People's Hospital)from April 2022 to April 2024 were prospectively selected as the study group,and the patients were grouped into mild,moderate and severe groups according to Gensimi scores,and another 186 patients with healthy physical examination during the same peri-od were selected as the control group.Enzyme-linked immunosorbent assay(ELISA)was used to detect IL-12p70 levels.Automatic coagulation instrument was used to detect the levels of PC and PS.The influencing factors of severe coronary artery stenosis in coronary heart disease were analyzed by multivariate Logistic re-gression analysis.Receiver operating characteristic(ROC)curve was plotted to analyze the diagnostic value of CCTA parameters combined with serum IL-12p70,PC and PS in the diagnosis of severe coronary artery steno-sis in coronary heart disease.Results The serum level of IL-12p70 in the study group was greatly higher than that in the control group(P＜0.05),and the levels of PC and PS were greatly lower than those in the control group(P＜0.05).Minimum lumen diameter(MLD),minimum tubular neck area(MLA),serum PC,and PS levels were sequentially decreased in the mild,moderate,and severe groups(P＜0.05),and percentage area stenosis(％AS),percentage diameter stenosis(％DS),and serum IL-12p70 levels were sequentially increased(P＜0.05).According to multivariate Logistic regression analysis,IL-12p70 was a risk factor for severe coro-nary artery stenosis in coronary heart disease(P＜0.05),and PC and PS were protective factors(P＜0.05).According to the ROC curve,the area under the curve(AUC)of MLD,MLA,％AS,％DS,serum IL-12p70,PC,and PS for the diagnosis of severe coronary artery stenosis in coronary heart disease was 0.810,0.767,0.782,0.779,0.776,0.809,and 0.805.The AUC of combined diagnosis for severe coronary artery stenosis in coronary heart disease was 0.982,which was better than that of individual diagnosis(Zcombination vs.MLD=2.489,Zcombination vs.MLA=2.502,Zcombination vs.％AS=2.531,Zcombination vs.％DS=2.602,Zcombination vs.IL-12p70=2.643,Zcombination vs.PC=2.537,Zcombination vs.PS=2.546,all P＜0.05).Conclusion Serum IL-12p70 is greatly increased in patients with coronary heart disease,PC and PS levels are greatly reduced.CCTA combined with serum IL-12p70,PC,and PS could effectively improve their value in diagnosing degree of coronary artery stenosis in cor-onary heart disease.

Research in photodynamic therapy (PDT) primarily focuses on enhancing light penetration depth, improving oxygen supply, and optimizing photosensitizer delivery. Notably, the delivery efficiency of the photosensitizer is crucial for therapeutic efficacy. Carboxyl-substituted phthalocyanines, as important photosensitizing molecules, possess unique chemical modification sites that enable direct targeted delivery or integration into diverse delivery systems. Their synthesis predominantly employs mixed- or cross-condensation, selective synthesis, and axial modification strategies to introduce carboxyl groups. However, their inherent hydrophobicity significantly hinders effective delivery. To address this limitation, modifications with peptides or quaternary ammonium salt derivatives may facilitate precise delivery to tumor cells and pathogens. With advances in nanotechnology, carboxyl-substituted phthalocyanines can serve as key photosensitizer modules, effectively integrated into nanomaterials such as biomacromolecules, inorganic metals, and polymers for both active and passive delivery. Recently, researchers have exploited the π-π stacking and other intermolecular forces among carboxyl-substituted phthalocyanine molecules to drive their self-assembly into nano-micelles, enabling carrier-free delivery or co-delivery with other therapeutic agents for synergistic effects. This review systematically outlines the synthesis strategies for carboxyl-substituted phthalo-cyanines. Taking mono-carboxyl-substituted zinc phthalocyanine as a model molecule, the performance of three delivery modalities were compared: single-molecule targeted delivery, nanocarrier-encapsulated delivery, and carrier-free self-assembled delivery, in terms of PDT efficacy, biocompatibility, and imaging-guided tracing capabilities, to provide a systematic technical framework for the rational design of novel modular photosensitizers and to advance the clinical translation of PDT in precision oncology and anti-infective therapy.
Photochemotherapy/methods* ; Indoles/administration & dosage* ; Isoindoles ; Photosensitizing Agents/administration & dosage* ; Drug Delivery Systems ; Humans