RESUMO
Reverse electron transfer (RET), an abnormal backward flow of electrons from complexes III/IV to II/I of mitochondria, causes the overproduction of a reduced-type CoQ to boost downstream production of mitochondrial superoxide anions that leads to ischemia-reperfusion injury (IRI) to organs. Herein, we studied low-coordinated gold nanoclusters (AuNCs) with abundant oxygen-binding sites to form an electron-demanding trapper that allowed rapid capture of electrons to compensate for the CoQ/CoQH2 imbalance during RET. The AuNCs were composed of only eight gold atoms that formed a Cs-symmetrical configuration with all gold atoms exposed on the edge site. The geometry and atomic configuration enhance oxygen intercalation to attain a d-band electron deficiency in frontier orbitals, forming an unusually high oxidation state for rapid mitochondrial reverse electron capture under a transient imbalance of CoQ/CoQH2 redox cycles. Using hepatic IRI cells/animals, we corroborated that the CoQ-like AuNCs prevent inflammation and liver damage from IRI via recovery of the mitochondrial function.
Assuntos
Elétrons , Ouro , Nanopartículas Metálicas , Oxigênio , Ouro/química , Nanopartículas Metálicas/química , Oxigênio/química , Oxigênio/metabolismo , Transporte de Elétrons , Sítios de Ligação , Animais , Ubiquinona/química , Ubiquinona/análogos & derivados , Mitocôndrias/metabolismo , Traumatismo por Reperfusão/metabolismo , Oxirredução , Humanos , CamundongosRESUMO
Fungal secondary metabolite (SM) biosynthetic gene clusters (BGCs) containing dimethylallyltryptophan synthases (DMATSs) produce structurally diverse prenylated indole alkaloids with wide-ranging activities that have vast potential as human therapeutics. To discover new natural products produced by DMATSs, we mined the Department of Energy Joint Genome Institute's MycoCosm database for DMATS-containing BGCs. We found a DMATS BGC in Aspergillus homomorphus CBS 101889, which also contains a nonribosomal peptide synthetase (NRPS). This BGC appeared to have a previously unreported combination of genes, which suggested the cluster might make novel SMs. We refactored this BGC with highly inducible promoters into the model fungus Aspergillus nidulans. The expression of this refactored BGC in A. nidulans resulted in the production of eight tryptophan-containing diketopiperazines, six of which are new to science. We have named them homomorphins A-F (2, 4-8). Perhaps even more intriguingly, to our knowledge, this is the first discovery of C4-prenylated tryptophan-containing diketopiperazines and their derivatives. In addition, the NRPS from this BGC is the first described that has the ability to promiscuously combine tryptophan with either of two different amino acids, in this case, l-valine or l-allo-isoleucine.
Assuntos
Aspergillus nidulans , Aspergillus , Dicetopiperazinas , Peptídeo Sintases , Triptofano , Triptofano/metabolismo , Triptofano/química , Dicetopiperazinas/química , Aspergillus nidulans/genética , Aspergillus nidulans/metabolismo , Aspergillus/química , Peptídeo Sintases/metabolismo , Peptídeo Sintases/genética , Estrutura Molecular , Família Multigênica , Alcaloides Indólicos/química , Alcaloides Indólicos/metabolismo , Alquil e Aril Transferases/metabolismo , Alquil e Aril Transferases/genéticaRESUMO
Polystyrene (PS) is one of the most used yet infrequently recycled plastics. Although manufactured on the scale of 300 million tons per year globally, current approaches toward PS degradation are energy- and carbon-inefficient, slow, and/or limited in the value that they reclaim. We recently reported a scalable process to degrade post-consumer polyethylene-containing waste streams into carboxylic diacids. Engineered fungal strains then upgrade these diacids biosynthetically to synthesize pharmacologically active secondary metabolites. Herein, we apply a similar reaction to rapidly convert PS to benzoic acid in high yield. Engineered strains of the filamentous fungus Aspergillus nidulans then biosynthetically upgrade PS-derived crude benzoic acid to the structurally diverse secondary metabolites ergothioneine, pleuromutilin, and mutilin. Further, we expand the catalog of plastic-derived products to include spores of the industrially relevant biocontrol agent Aspergillus flavus Af36 from crude PS-derived benzoic acid.
Assuntos
Produtos Biológicos , Poliestirenos , Poliestirenos/metabolismo , Produtos Biológicos/metabolismo , Plásticos/metabolismo , Polietileno/metabolismo , Aspergillus flavus/metabolismoRESUMO
The dynamic oscillation implicated in structural heterogeneity during the self-assembly of amyloid peptide 1-42 (Aß42) may play a crucial role in eliciting cellular responses. We developed a real-time monitoring platform to observe an oscillatory non-equilibrium interaction that dominated the Aß42 clearance by neuronal cells during interplay with an oscillator (lipopolysaccharide, LPS). Molecular dynamics studies indicated that the electrostatic and hydrophobic segments of LPS involved in the temporary heteromolecular association and slightly decelerated the intrinsic thermally-induced protein dynamics of Aß42. A bait-specific intervention strategy could temporarily slow down the self-propagation of Aß42 to extend the lifetime of autonomous oscillation and augment Aß42 clearance of neuronal cells. The lifetime increment of oscillation shows a bait concentration-dependent manner to reflect the non-equilibrium binding strength. This relationship may serve as a predictor for Alzheimer's disease drug discovery.
Assuntos
Doença de Alzheimer , Lipopolissacarídeos , Humanos , Peptídeos beta-Amiloides/química , Doença de Alzheimer/metabolismo , Fragmentos de Peptídeos/químicaRESUMO
Context: Knee osteoarthritis is a common form of joint disease found in humans and one of the leading causes of disability globally. Knee osteoarthritis (KOA) is responsible for a higher number of disabilities than any other medical condition affecting activities of daily living (ADL). To date no definitive, conventional medical protocol is available to deal with KOA. Objectives: The study intended to clinically investigate whether the benefits of acupuncture in the treatment of KOA) could be augmented by the addition of Chinese herbal fumigation steam therapy (CHFST) to the treatment protocol and to what degree it had benefits. Design: The research team designed a three-armed, randomized, controlled trial. The sample size was determined by analysis of power; for a sample size of 42, the power was 83.5%; the effect size was 0.5; and the α was 0.05. Setting: The setting was the traumatology department in the Chinese Medicine Branch of Taipei City Joint Hospital in Kun Ming, Taiwan. Participants: Participants were 45 males and females between the ages of 35 and 75, who were patients in the traumatology department and who were suffering from bilateral knee osteoarthritis. Three participants were lost to follow-up. Interventions: Participants were randomly assigned to one of three groups, each with 15 participants; (1) the control group, who received acupuncture only; (2) the normal CHFST group, an intervention group who received acupuncture plus a normal dose of CHFST; and (3) the one-sixteenth CHFST group, an intervention group who received acupuncture plus one-sixteenth of a normal dose of CHFST. Participants underwent biweekly treatments for four consecutive weeks. Outcomes Measures: The primary outcome measures included a visual analog scale (VAS) to assess variations in pain intensity and a goniometer measure for range of motion (ROM). Results: The addition of CHFST to acupuncture in the treatment of KOA significantly reduced pain (P = .0017) for the normal CHFST group compared to the control group and the one-sixteenth CHFST group. Chinese medical interventions overall for all groups showed a decrease in pain and increases in ROM, and health related quality of life (HrQoL). Conclusions: CHFST, in conjunction with acupuncture, showed promise in the treatment of KOA in reducing pain, increasing ROM, and improving quality of life (QoL).
Assuntos
Terapia por Acupuntura , Osteoartrite do Joelho , Masculino , Feminino , Humanos , Adulto , Pessoa de Meia-Idade , Idoso , Osteoartrite do Joelho/terapia , Qualidade de Vida , Vapor , Atividades Cotidianas , Fumigação , Terapia por Acupuntura/métodos , Dor , Resultado do TratamentoRESUMO
Type I interferon (IFN-I) has a well-known function in controlling viral infections, but its contribution in hepatocyte proliferation and hepatocellular carcinoma (HCC) formation remains unclear. Mice deficient in IFN-α receptor expression in whole mice or only in hepatocytes (Ifnar-/- and IfnarΔliver) were used to investigate the role of IFN-I signaling in cell proliferation and cancer formation in the liver. Ifnar-/- mice were resistant to chemical-induced HCC formation in the absence of infection. The results show that low grade of IFN-I and interferon-stimulated gene were expressed substantially in naïve mouse liver. The low level of IFN-I activation is constantly present in mouse liver after weaning and negatively modulates forkhead box O hepatic expression. The IFN-I signaling can be partially blocked by the clearance of lipopolysaccharide. Mice lacking IFN-I signaling have lower basal proliferation activity and delayed liver regeneration processes after two-thirds partial hepatectomy. The activation of IFN-I signaling on hepatocyte controls glucose homeostasis and lipid metabolism to support proliferation potency and long-term tumorigenesis. Our results reveal a positive role of low-grade IFN-I singling to hepatocyte proliferation and HCC formation by modulating glucose homeostasis and lipid metabolism.
Assuntos
Carcinoma Hepatocelular/metabolismo , Hepatócitos/metabolismo , Interferon Tipo I/metabolismo , Neoplasias Hepáticas/metabolismo , Regeneração Hepática/fisiologia , Animais , Proliferação de Células/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transdução de Sinais/fisiologiaRESUMO
Weight loss by increasing energy consumption of thermogenic adipocytes to overcome obesity remains a challenge. Herein, we established a transdermal device that was based on the local and temporarily controlled delivery of succinate (SC), a tricarboxylic acid cycle metabolic intermediate to stimulate the thermogenesis pathway of uncoupling protein 1 (UCP1) and accelerate energy dissipation of brown adipose tissue (BAT) under the dorsal interscapular skin, further initiating the consumption of fatty acids by systemic metabolism. SC microneedle patches significantly suppressed weight gain and fat accumulation of remote organs, including liver and peripheral white adipose tissue (WAT) in high-fat diet-induced obese mice. mRNA expression levels of Ucp1 in BAT and other browning markers in WAT were significantly elevated in the mice that were treated with SC microneedle. Thus, the energy dissipation of BAT using UCP1-mediated thermogenesis accelerated by the transdermal delivery of SC may become a potential and effective strategy for preventing obesity.
Assuntos
Adipócitos Marrons , Ácido Succínico , Camundongos , Animais , Adipócitos Marrons/metabolismo , Metabolismo Energético , Termogênese/genética , Dieta Hiperlipídica/efeitos adversos , Obesidade/tratamento farmacológico , Obesidade/metabolismo , Camundongos Endogâmicos C57BLRESUMO
BACKGROUND: Inappropriate management of medications is a major threat to homebound patients with chronic conditions. Despite many efforts in improving medication reconciliation in ambulatory and inpatient settings, little research has focused on home care settings. In 2016, Taiwan initiated the Integrated Home Health Care programme, which was intended to reduce potentially inappropriate medication management and risks of uncontrolled polypharmacy through the integration of different medication sources for chronic conditions among homebound patients. This study investigated factors associated with having home care physicians as an integrated source of medications for chronic conditions among homebound patients. METHOD: This retrospective cohort study enrolled 3142 community-dwelling homebound patients from Taipei City Hospital. Homebound patients' adherence to using home care physicians as an integrated source of chronic condition medications was defined as having all prescriptions for their chronic conditions prescribed by a single home care physician for at least 6 months. Both patient and home care physician characteristics were analysed. Multivariable logistic regression was applied. RESULTS: Of the 3142 patients with chronic conditions, 1002 (31.9%) had consistently obtained all medications for their chronic illnesses from their home care physicians for 6 months and 2140 (68.1%) had not. The most common chronic diseases among homebound patients were hypertension, diabetes mellitus, dementia, cerebrovascular disease and constipation. Oldest-old patients with poor functional status, fewer daily medications, no co-payment exemption and no recent inpatient experience were more likely to adhere to this medication integration system. In addition, patients whose outpatient physicians were also their home care physicians were more likely to adhere to the system. CONCLUSIONS: The finding suggests that building trust and enhancing communication among homebound patients, caregivers and home care physicians are critical. Patient and provider variations highlight the need for further improvement and policy modification for medication reconciliation and management in home care settings. The improvement in medication management and care integration in home care settings may reduce misuse and polypharmacy and improve homebound patients' safety.
Assuntos
Serviços de Assistência Domiciliar , Pacientes Domiciliares , Médicos , Idoso , Idoso de 80 Anos ou mais , Doença Crônica , Humanos , Polimedicação , Estudos RetrospectivosRESUMO
In living systems, non-equilibrium states that control the assembly-disassembly of cellular components underlie the gradual complexification of life, whereas in nonliving systems, most molecules follow the laws of thermodynamic equilibrium to sustain dynamic consistency. Little is known about the roles of non-equilibrium states of interactions between supramolecules in living systems. Here, a non-equilibrium state of interaction between supramolecular lipopolysaccharide (LPS) and Aß42, an aggregate-prone protein that causes Alzheimer's disease (AD), was identified. Structurally, Aß42 presents a specific groove that is recognized by the amphiphilicity of LPS bait in a non-equilibrium manner. Functionally, the transient complex elicits a cellular response to clear extracellular Aß42 deposits in neuronal cells. Since the impaired clearance of toxic Aß42 deposits correlates with AD pathology, the non-equilibrium LPS and Aß42 could represent a useful target for developing AD therapeutics.
Assuntos
Peptídeos beta-Amiloides/metabolismo , Lipopolissacarídeos/metabolismo , Fragmentos de Peptídeos/metabolismo , Peptídeos beta-Amiloides/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Lipopolissacarídeos/química , Substâncias Macromoleculares/química , Substâncias Macromoleculares/metabolismo , Substâncias Macromoleculares/farmacologia , Neurônios/citologia , Neurônios/metabolismo , Fragmentos de Peptídeos/química , Ligação ProteicaRESUMO
BACKGROUND/PURPOSE: Reactivation of herpes viruses poses threat to corneal graft survival. This study evaluated the presence of herpes simplex virus type 1 (HSV-1), HSV type 2 (HSV-2), and cytomegalovirus (CMV) DNA in recipient corneas and the aqueous humor of patients undergoing penetrating keratoplasty (PKP), and the impact on graft survival. METHODS: This retrospective study reviewed 90 eyes of 71 patients underwent PKP between 2008 and 2016. Cornea and aqueous humor samples were sent for polymerase chain reaction (PCR) testing for viral DNA. The main outcomes were PCR results and graft survival. RESULTS: Recipient corneas tested positive for HSV-1 in 47 eyes (52.2%), for HSV-2 in 24 eyes (26.7%), and for CMV in seven eyes (7.8%). Aqueous humor tested positive for HSV-1 in 44 eyes (48.9%), for HSV-2 in 25 eyes (27.8%), and for CMV in eight eyes (8.9%). The presence of aqueous HSV-1 DNA was associated with higher risk of graft failure (p = 0.005), whereas corneal HSV-1 DNA was not. The presence of HSV-2 DNA had no significant impact on graft survival. Aqueous CMV DNA was associated with higher risk of graft failure in univariate model, but not in multivariate model. CONCLUSION: There were high positive rates of HSV-1, HSV-2, and CMV DNA in recipient corneas and aqueous humor at the time of PKP, even among patients not suspected of latent viral infection. The presence of aqueous HSV-1 DNA was associated with higher risk of graft failure.
Assuntos
Sobrevivência de Enxerto , Ceratoplastia Penetrante , Humor Aquoso , Córnea , DNA Viral , Humanos , Estudos RetrospectivosRESUMO
The progress of wound regeneration relies on inflammation management, while neovascular angiogenesis is a critical aspect of wound healing. In this study, the bioactive core and corona synergism of quantized gold (QG) were developed to simultaneously address these complicated issues, combining the abilities to eliminate endotoxins and provide oxygen. The QG was constructed from ultrasmall nanogold and a loosely packed amine-based corona via a simple process, but it could nonetheless eliminate endotoxins (a vital factor in inflammation also called lipopolysaccharides) and provide oxygen in situ for the remodeling of wound sites. Even while capturing endotoxins through electrostatic interactions, the catalytic active sites inside the nanogold could maintain its surface accessibility to automatically transform the overexpressed hydrogen peroxide in hypoxic wound regions into oxygen. Since the inflammatory stage is an essential stage of wound healing, the provision of endotoxin clearance by the outer organic corona of the QG could slow inflammation in a way that subsequently promoted two other important stages of wound bed healing, namely proliferation and remodeling. Relatedly, the efficacy of two forms of the QG, a liquid form and a dressing form, was demonstrated at wound sites in this study, with both forms promoting the development of granulation, including angiogenesis and collagen deposition. Thus, the simply fabricated dual function nanocomposite presented herein not only offers reduced batch-to-batch variation but also increased options for homecare treatments.
Assuntos
Anti-Inflamatórios/farmacologia , Sequestradores de Radicais Livres/farmacologia , Ouro/química , Nanofibras/química , Cicatrização , Aminas/química , Animais , Anti-Inflamatórios/química , Bandagens , Hipóxia Celular , Células Cultivadas , Endotoxinas/toxicidade , Fibroblastos/efeitos dos fármacos , Sequestradores de Radicais Livres/química , Humanos , Peróxido de Hidrogênio/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Oxigênio/metabolismoRESUMO
A strong interaction between colistin, a last-resort antibiotic of the polymyxin family, and free lipopolysaccharide (LPS, also referred to as endotoxin), released from the Gram-negative bacterial (GNB) outer membrane (OM), has been identified that can decrease the antibacterial efficacy of colistin, potentially increasing the dose of this antibiotic required for treatment. The competition between LPS in the GNB OM and free LPS for the interaction with colistin was prevented by using a supramolecular trap to capture free LPS. The supramolecular trap, fabricated from a subnanometer gold nanosheet with methyl motifs (SAuM), blocks lipidâ A, preventing the interaction between lipidâ A and colistin. This can minimize endotoxemia and maximize the antibacterial efficacy of colistin, enabling colistin to be used at lower doses. Thus, the potential crisis of colistin resistance could be avoided.
Assuntos
Antibacterianos/uso terapêutico , Colistina/uso terapêutico , Animais , Antibacterianos/farmacologia , Colistina/farmacologia , Humanos , CamundongosRESUMO
Endotoxicity originating from a dangerous debris (i.e., lipopolysaccharide, LPS) of Gram-negative bacteria is a challenging clinical problem, but no drugs or therapeutic strategies that can successfully address this issue have been identified yet. In this study, we report a subnanometer gold cluster that can efficiently block endotoxin activity to protect against sepsis. The endotoxin blocker consists of a gold nanocluster that serves as a flakelike substrate and a coating of short alkyl motifs that act as an adhesive to dock with LPS by compacting the intramolecular hydrocarbon chain-chain distance ( d-spacing) of lipid A, an endotoxicity active site that can cause overwhelming cytokine induction resulting in sepsis progression. Direct evidence showed the d-spacing values of lipid A to be decreased from 4.19 Å to either 3.85 or 3.54 Å, indicating more dense packing densities in the presence of subnanometer gold clusters. In terms of biological relevance, the concentrations of key pro-inflammatory NF-κB-dependent cytokines, including plasma TNF-α, IL-6, and IL-1ß, and CXC chemokines, in LPS-challenged mice showed a noticeable decrease. More importantly, we demonstrated that the treatment of antiendotoxin gold nanoclusters significantly prolonged the survival time in LPS-induced septic mice. The ultrasmall gold nanoclusters could target lipid A of LPS to deactivate endotoxicity by compacting its packing density, which might constitute a potential therapeutic strategy for the early prevention of sepsis caused by Gram-negative bacterial infection.
Assuntos
Ouro/uso terapêutico , Lipídeo A/antagonistas & inibidores , Nanopartículas Metálicas/uso terapêutico , Sepse/terapia , Animais , Citocinas/sangue , Lipopolissacarídeos/efeitos adversos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Sepse/sangue , Sepse/induzido quimicamenteRESUMO
BACKGROUND: Periodontitis is a frequently cited extraintestinal manifestation of Crohn's disease (CD). Despite a plethora of investigations and a recent meta-analysis linking CD and periodontitis, no study has estimated the risk of periodontitis among CD patients with respect to a comparison group nor has any investigation analyzed the effect of CD-specific medications on the risk of periodontitis. The present cohort study compared CD patients and matched subjects without a history of inflammatory bowel disease (IBD) to estimate the effect of CD and CD-specific pharmaceutical prescriptions on the risk of developing periodontitis by leveraging a population-based dataset in Taiwan. METHODS: We sourced 6657 CD patients and 26,628 comparison subjects without a history of IBD from the Taiwan National Health Insurance Database. Cox proportional hazards regressions were used to estimate the risk of subsequent periodontitis by CD status and pharmaceutical prescription during the follow-up period. RESULTS: After adjusting for socioeconomic status (SES), urbanicity, selected medical co-morbidities, and CD-specific pharmaceutical prescriptions, the hazard ratio (HR) for subsequent periodontitis among patients with CD was 1.36 (95% CI = 1.25-1.48) that of comparison subjects. There was not a significant difference in risk between genders or across ages. Steroids (95% CI = 0.66-0.77) appeared to confer a protective effect and Aspirin, Plavix, and Licodin were marginally protective (95% CI = 0.76-0.95). CONCLUSION: This is the first study to report an increased HR for subsequent periodontitis among CD patients when compared to matched comparison subjects without IBD. The protective effect of some pharmaceuticals may suggest that treatment of CD protects against periodontitis.
Assuntos
Doença de Crohn , Glucocorticoides/uso terapêutico , Periodontite , Adulto , Idoso , Estudos de Casos e Controles , Comorbidade , Doença de Crohn/tratamento farmacológico , Doença de Crohn/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Periodontite/diagnóstico , Periodontite/epidemiologia , Modelos de Riscos Proporcionais , Substâncias Protetoras/uso terapêutico , Medição de Risco , Fatores de Risco , Fatores Socioeconômicos , Taiwan/epidemiologiaRESUMO
Photodynamic therapy (PDT) typically involves oxygen (O2 ) consumption and therefore suffers from greatly limited anticancer therapeutic efficacy in tumor hypoxia. Here, it is reported for the first time that amine-terminated, PAMAM dendrimer-encapsulated gold nanoclusters (AuNCs-NH2 ) can produce O2 for PDT via their intrinsic catalase-like activity. The AuNCs-NH2 not only show optimum H2 O2 consumption via the catalase-like activity over the physiological pH range (i.e., pH 4.8-7.4), but also extend such activity to acidic conditions. The possible mechanism is deduced from that the enriched tertiary amines of dendrimers are easily protonated in acidic solutions to facilitate the preadsorption of OH on the metal surface, thereby favorably triggering the catalase-like reaction. By taking advantage of the exciting feature on AuNCs-NH2 , the possibility to supply O2 via the catalase-like activity of AuNCs-NH2 for PDT against hypoxia of cancer cells was further studied. This proof-of-concept study provides a simple way to combine current O2 -dependent cancer therapy of PDT to overcome cancer cell hypoxia, thus achieving more effective anticancer treatments.
Assuntos
Catalase/metabolismo , Ouro/química , Oxigênio/química , Fotoquimioterapia/métodos , Catalase/química , Linhagem Celular Tumoral , HumanosRESUMO
Infectious bronchitis virus (IBV) variants constantly emerge and pose economic threats to poultry farms worldwide. Numerous studies on the molecular and pathogenic characterization of IBV variants have been performed between 2007 and 2017, which we have reviewed herein. We noted that viral genetic mutations and recombination events commonly gave rise to distinct IBV genotypes, serotypes and pathotypes. In addition to characterizing the S1 genes, full viral genomic sequencing, comprehensive antigenicity, and pathogenicity studies on emerging variants have advanced our understanding of IBV infections, which is valuable for developing countermeasures against IBV field outbreaks. This review of IBV variants provides practical value for understanding their phylogenetic relationships and epidemiology from both regional and worldwide viewpoints.
Assuntos
Genoma Viral/genética , Vírus da Bronquite Infecciosa/patogenicidade , Animais , Genótipo , Humanos , SorogrupoRESUMO
Heparin-binding hemagglutinin (HBHA) is a 199 amino acid virulence factor at the envelope of Mycobacterium tuberculosis that contributes to latent tuberculosis. The binding of HBHA to respiratory epithelial cells, which leads to extrapulmonary dissemination of the pathogen, is mediated by cell-surface heparan sulfate (HS). We report the structural characterization of the HBHA/HS complex by NMR spectroscopy. To develop a model for the molecular recognition, the first chemically synthesized uniformly 13 C- and 15 N-labeled HS octasaccharide and a uniformly 13 C- and 15 N-labeled form of HBHA were prepared. Residues 180-195 at the C-terminal region of HBHA show large chemical shift perturbation upon association with the octasaccharide. Molecular dynamics simulations conforming to the multidimensional NMR data revealed key electrostatic and even hydrophobic interactions between the binding partners that may aid in the development of agents targeting the binding event.
Assuntos
Heparitina Sulfato/química , Lectinas/química , Mycobacterium tuberculosis/química , Oligossacarídeos/química , Modelos Moleculares , Estrutura MolecularRESUMO
Despite nanoparticulate platinum (nano-Pt) has been validated to be acting as a platinum-based prodrug for anticancer therapy, the key factor in controlling its cytotoxicity remains to be clarified. In this study, it is found that the corrosion susceptibility of nano-Pt can be triggered by inducing the oxidization of superficial Pt atoms, which can kill both cisplatin-sensitive/resistance cancer cells. Direct evidence in the oxidization of superficial Pt atoms is validated to observe the formation of platinum oxides by X-ray absorption spectroscopy. The cytotoxicity is originated from the dissolution of nano-Pt followed by the release of highly toxic Pt ions during the corrosion process. Additionally, the limiting autophagy induction by nano-Pt might prevent cancer cells from acquiring autophagy-related drug resistance. With such advantages, the possibility of further autophagy-related drug resistance could be substantially reduced or even eliminated in cancer cells treated with nano-Pt. Moreover, nano-Pt is demonstrated to kill cisplatin-resistant cancer cells not only by inducing apoptosis but also by inducing necrosis for pro-inflammatory/inflammatory responses. Thus, nano-Pt treatment might bring additional therapeutic benefits by regulating immunological responses in tumor microenvironment. These findings support the idea that utilizing nano-Pt for its cytotoxic effects might potentially benefit patients with cisplatin resistance in clinical chemotherapy.
Assuntos
Antineoplásicos/farmacologia , Autofagia/efeitos dos fármacos , Cisplatino/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Nanopartículas/química , Óxidos/farmacologia , Platina/farmacologia , Pró-Fármacos/farmacologia , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Corrosão , Humanos , Espectroscopia Fotoeletrônica , Espectroscopia por Absorção de Raios XRESUMO
The cytotoxicity of nanozymes has drawn much attention recently because their peroxidase-like activity can decompose hydrogen peroxide (H2 O2 ) to produce highly toxic hydroxyl radicals (â¢OH) under acidic conditions. Although catalytic activities of nanozymes are highly associated with their surface properties, little is known about the mechanism underlying the surface coating-mediated enzyme-like activities. Herein, it is reported for the first time that amine-terminated PAMAM dendrimer-entrapped gold nanoclusters (AuNCs-NH2 ) unexpectedly lose their peroxidase-like activity while still retaining their catalase-like activity in physiological conditions. Surprisingly, the methylated form of AuNCs-NH2 (i.e., MAuNCs-N(+) R3 , where R = H or CH3 ) results in a dramatic recovery of the intrinsic peroxidase-like activity while blocking most primary and tertiary amines (1°- and 3°-amines) of dendrimers to form quaternary ammonium ions (4°-amines). However, the hidden peroxidase-like activity is also found in hydroxyl-terminated dendrimer-encapsulated AuNCs (AuNCs-OH, inside backbone with 3°-amines), indicating that 3°-amines are dominant in mediating the peroxidase-like activity. The possible mechanism is further confirmed that the enrichment of polymeric 3°-amines on the surface of dendrimer-encapsulated AuNCs provides sufficient suppression of the critical mediator â¢OH for the peroxidase-like activity. Finally, it is demonstrated that AuNCs-NH2 with diminished cytotoxicity have great potential for use in primary neuronal protection against oxidative damage.
Assuntos
Aminas/química , Aminas/farmacologia , Ouro/química , Nanopartículas Metálicas/química , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Polímeros/química , Animais , Dendrímeros/química , Humanos , Peróxido de Hidrogênio/farmacologia , Oxirredução/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismoRESUMO
In this study, we sought to control the assembly of an endotoxin known as the biologically supramolecular lipopolysaccharide (LPS, which consists of three portions: an O antigen, a core carbohydrate, and a lipid A molecule) in order to modulate immunological responses in a manner that has the potential for utilization in vaccine development. Changing the structures of LPS aggregates from lamellas to specific nonlamellas (i.e., cubosomes and hexosomes) can dramatically enhance the strength of LPS in causing inflammatory responses, leading to highly active responses. In order to control the formation of cubosome-free and hexosome-free nonlamellas, we designed a simple strategy based on the use of hydrophilic gold nanodots (AuNDs) to control LPS assembly to facilitate the formation of stable endotoxin nanovesicles, which are stable precursors of cubosomes and hexosomes with specific immunological effects. Structurally, the wall thicknesses of these nanovesicles are exactly twice the lengths of a single LPS molecule, indicating that the LPS molecules adopt a tail-to-tail arrangement (with the lipid A portions acting as the tail domain). The involvement of the hydrophilic AuNDs to laterally link polar domains of LPS can result in the progressive extension of an endotoxically active zone of lipid A assembly, leading to the eventual formation of large-size nanovesicles. Our results showed that endotoxin nanovesicles with such dense lipid A units can elicit the stronger inflammatory gene expressions, including interleukin 6 (IL-6), IL-1A, TNF-α, C-X-C chemokine ligand (CXCL) 1, 2, and 11, which have characteristics of T-helper 1 adjuvants. These findings provide evidence that the concept of manipulating the surface hydrophilicity of AuNDs to control LPS assembly in order to avoid the formation of highly active cubosomes and hexosomes, and thereby modulate immunological responses appropriately, could prove useful in vaccine development.