Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 18 de 18
Filtrar
1.
Nat Med ; 2024 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-38783139

RESUMO

Hematopoietic cell transplantation (HCT) uses cytotoxic chemotherapy and/or radiation followed by intravenous infusion of stem cells to cure malignancies, bone marrow failure and inborn errors of immunity, hemoglobin and metabolism. Lung injury is a known complication of the process, due in part to disruption in the pulmonary microenvironment by insults such as infection, alloreactive inflammation and cellular toxicity. How microorganisms, immunity and the respiratory epithelium interact to contribute to lung injury is uncertain, limiting the development of prevention and treatment strategies. Here we used 278 bronchoalveolar lavage (BAL) fluid samples to study the lung microenvironment in 229 pediatric patients who have undergone HCT treated at 32 children's hospitals between 2014 and 2022. By leveraging paired microbiome and human gene expression data, we identified high-risk BAL compositions associated with in-hospital mortality (P = 0.007). Disadvantageous profiles included bacterial overgrowth with neutrophilic inflammation, microbiome contraction with epithelial fibroproliferation and profound commensal depletion with viral and staphylococcal enrichment, lymphocytic activation and cellular injury, and were replicated in an independent cohort from the Netherlands (P = 0.022). In addition, a broad array of previously occult pathogens was identified, as well as a strong link between antibiotic exposure, commensal bacterial depletion and enrichment of viruses and fungi. Together these lung-immune system-microorganism interactions clarify the important drivers of fatal lung injury in pediatric patients who have undergone HCT. Further investigation is needed to determine how personalized interpretation of heterogeneous pulmonary microenvironments may be used to improve pediatric HCT outcomes.

2.
medRxiv ; 2023 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-38077035

RESUMO

Lung injury is a major determinant of survival after pediatric hematopoietic cell transplantation (HCT). A deeper understanding of the relationship between pulmonary microbes, immunity, and the lung epithelium is needed to improve outcomes. In this multicenter study, we collected 278 bronchoalveolar lavage (BAL) samples from 229 patients treated at 32 children's hospitals between 2014-2022. Using paired metatranscriptomes and human gene expression data, we identified 4 patient clusters with varying BAL composition. Among those requiring respiratory support prior to sampling, in-hospital mortality varied from 22-60% depending on the cluster (p=0.007). The most common patient subtype, Cluster 1, showed a moderate quantity and high diversity of commensal microbes with robust metabolic activity, low rates of infection, gene expression indicating alveolar macrophage predominance, and low mortality. The second most common cluster showed a very high burden of airway microbes, gene expression enriched for neutrophil signaling, frequent bacterial infections, and moderate mortality. Cluster 3 showed significant depletion of commensal microbes, a loss of biodiversity, gene expression indicative of fibroproliferative pathways, increased viral and fungal pathogens, and high mortality. Finally, Cluster 4 showed profound microbiome depletion with enrichment of Staphylococci and viruses, gene expression driven by lymphocyte activation and cellular injury, and the highest mortality. BAL clusters were modeled with a random forest classifier and reproduced in a geographically distinct validation cohort of 57 patients from The Netherlands, recapitulating similar cluster-based mortality differences (p=0.022). Degree of antibiotic exposure was strongly associated with depletion of BAL microbes and enrichment of fungi. Potential pathogens were parsed from all detected microbes by analyzing each BAL microbe relative to the overall microbiome composition, which yielded increased sensitivity for numerous previously occult pathogens. These findings support personalized interpretation of the pulmonary microenvironment in pediatric HCT, which may facilitate biology-targeted interventions to improve outcomes.

3.
ACS Appl Mater Interfaces ; 15(26): 31803-31811, 2023 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-37345639

RESUMO

Polymers that undergo shape changes in response to external stimuli can serve as actuators and offer significant potential in a variety of technologies, including biomimetic artificial muscles and soft robotics. Current polymer artificial muscles possess major challenges for various applications as they often require extreme and non-practical actuation conditions. Thus, exploring actuators with new or underutilized stimuli may broaden the application of polymer-based artificial muscles. Here, we introduce an all-solid fuel-powered actuator that contracts and expands when exposed to H2 and O2 via redox reactions. This actuator demonstrates a fully reversible actuation magnitude of up to 3.8% and achieves a work capacity of 120 J/kg. Unlike traditional chemical actuators, our actuator eliminates the need for electrolytes, electrodes, and the application of external voltage. Moreover, it offers athermal actuation by avoiding the drawbacks of thermal actuators. Remarkably, the actuator maintains its actuated position under load when not stimulated, without consuming energy (i.e., catch state). These fuel-powered fiber actuators were embedded in a soft humanoid hand to demonstrate finger-bending motions. In terms of two main actuation metrics, stress-free contraction strain and blocking stress, the presented artificial muscle outperforms reported polymer redox actuators. The fuel-powered actuator developed in this work creates new avenues for the application of redox polymers in soft robotics and artificial muscles.

4.
Transplant Cell Ther ; 28(11): 737-746, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-35902050

RESUMO

The Coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has significantly impacted global health and healthcare delivery systems. To characterize the secondary effects of the COVID-19 pandemic and mitigation strategies used in the delivery of hematopoietic stem cell transplantation (HSCT) care, we performed a comprehensive literature search encompassing changes in specific donor collection, processing practices, patient outcomes, and patient-related concerns specific to HSCT and HSCT-related healthcare delivery. In this review, we summarize the available literature on the secondary impacts the COVID-19 pandemic on the fields of HSCT and cellular therapy. The COVID-19 pandemic has had numerous secondary impacts on patients undergoing HSCT and the healthcare delivery systems involved in providing complex care to HSCT recipients. Institutions must identify these influences on outcomes and adjust accordingly to maintain and improve outcomes for the transplantation and cellular therapy community.


Assuntos
COVID-19 , Pandemias , Humanos , COVID-19/epidemiologia , SARS-CoV-2 , Ecossistema , Atenção à Saúde
5.
Front Immunol ; 12: 739430, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34764957

RESUMO

Human complement C4 is one of the most diverse but heritable effectors for humoral immunity. To help understand the roles of C4 in the defense and pathogenesis of autoimmune and inflammatory diseases, we determined the bases of polymorphisms including the frequent genetic deficiency of C4A and/or C4B isotypes. We demonstrated the diversities of C4A and C4B proteins and their gene copy number variations (CNVs) in healthy subjects and patients with autoimmune disease, such as type 1 diabetes, systemic lupus erythematosus (SLE) and encephalitis. We identified subjects with (a) the fastest migrating C4B allotype, B7, or (b) a deficiency of C4B protein caused by genetic mutation in addition to gene copy-number variation. Those variants and mutants were characterized, sequenced and specific techniques for detection developed. Novel findings were made in four case series. First, the amino acid sequence determinant for C4B7 was likely the R729Q variation at the anaphylatoxin-like region. Second, in healthy White subject MS630, a C-nucleotide deletion at codon-755 led to frameshift mutations in his single C4B gene, which was a private mutation. Third, in European family E94 with multiplex lupus-related mortality and low serum C4 levels, the culprit was a recurrent haplotype with HLA-A30, B18 and DR7 that segregated with two defective C4B genes and identical mutations at the donor splice site of intron-28. Fourth, in East-Asian subject E133P with anti-NMDA receptor encephalitis, the C4B gene had a mutation that changed tryptophan-660 to a stop-codon (W660x), which was present in a haplotype with HLA-DRB1*04:06 and B*15:27. The W660x mutation is recurrent among East-Asians with a frequency of 1.5% but not detectable among patients with SLE. A meticulous annotation of C4 sequences revealed clusters of variations proximal to sites for protein processing, activation and inactivation, and binding of interacting molecules.


Assuntos
Doenças Autoimunes/genética , Complemento C4b/genética , Variações do Número de Cópias de DNA , Dosagem de Genes , Imunidade Humoral/genética , Mutação , Doenças Autoimunes/diagnóstico , Doenças Autoimunes/etnologia , Doenças Autoimunes/imunologia , Estudos de Casos e Controles , Complemento C4a/deficiência , Complemento C4a/genética , Complemento C4a/imunologia , Complemento C4b/deficiência , Complemento C4b/imunologia , Feminino , Frequência do Gene , Predisposição Genética para Doença , Humanos , Masculino , Fenótipo
6.
J Clin Oncol ; 39(21): 2397-2409, 2021 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-33835855

RESUMO

PURPOSE: Ultrahigh resolution (UHR) HLA matching is reported to result in better outcomes following unrelated donor hematopoietic cell transplantation, improving survival and reducing post-transplant complications. However, most studies included relatively small numbers of patients. Here we report the findings from a large, multicenter validation study. METHODS: UHR HLA typing was available on 5,140 conventionally 10 out of 10 HLA-matched patients with malignant disease transplanted between 2008 and 2017. RESULTS: After UHR HLA typing, 82% of pairs remained 10 out of 10 UHR-matched; 12.3% of patients were 12 out of 12 UHR HLA-matched. Compared with 12 out of 12 UHR-matched patients, probabilities of grade 2-4 acute graft-versus-host disease (aGVHD) were significantly increased with UHR mismatches (overall P = .0019) and in those patients who were HLA-DPB1 T-cell epitope permissively mismatched or nonpermissively mismatched (overall P = .0011). In the T-cell-depleted subset, the degree of UHR HLA mismatch was only associated with increased transplant-related mortality (TRM) (overall P = .0068). In the T-cell-replete subset, UHR HLA matching was associated with a lower probability of aGVHD (overall P = .0020); 12 out of 12 UHR matching was associated with reduced TRM risk when compared with HLA-DPB1 T-cell epitope permissively mismatched patients, whereas nonpermissive mismatching resulted in a greater risk (overall P = .0003). CONCLUSION: This study did not confirm that UHR 12 out of 12 HLA matching increases the probability of overall survival but does demonstrate that aGVHD risk, and in certain settings TRM, is lowest in UHR HLA-matched pairs and thus warrants consideration when multiple 10 out of 10 HLA-matched donors of equivalent age are available.


Assuntos
Transplante de Células-Tronco Hematopoéticas/métodos , Teste de Histocompatibilidade/métodos , Condicionamento Pré-Transplante/métodos , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Doadores não Relacionados , Adulto Jovem
7.
Bone Marrow Transplant ; 54(8): 1354-1360, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-30696997

RESUMO

Limited data exist on characteristics of central nervous system viruses (CNS-V) in allogeneic hematopoietic stem cell transplant (HCT) recipients. Between 2007 and 2015, the Center for International Blood and Marrow Transplant Research (CIBMTR) received information on 27,532 patients undergoing HCT. Of these, centers reported 165 HCT recipients with CNS-V detected in cerebrospinal fluid within 6 months after HCT. CNS viruses predominantly included human herpes virus 6 (HHV-6) (73%), followed by Epstein-Barr Virus (10%), cytomegalovirus (3%), varicella zoster virus (3%), herpes simplex virus (3%) and Adenovirus (3%). Median time of viral detection in CNS was 31 days after HCT; and viral detection was earlier in patients with CNS HHV-6. Concurrent viremia occurred in 52% of patients. Cord blood transplant recipients (CBT) accounted for the majority (53%) of patients with CNS-V. Myeloablative conditioning (65%), use of fludarabine (63%), or use of anti-thymocyte globulin (61%) were also predominant. Overall survival from the time of detection of CNS-V was 50% at 6 months and 30% at 5 years. Infections were the leading cause of death (32%). In summary, CBT recipients predominated in the population with CNS-V. Outcomes after CNS-V were poor with significant mortality seen in the first 6 months.


Assuntos
DNA Viral/líquido cefalorraquidiano , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Condicionamento Pré-Transplante/efeitos adversos , Viroses/sangue , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Feminino , Transplante de Células-Tronco Hematopoéticas/métodos , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Condicionamento Pré-Transplante/métodos , Adulto Jovem
8.
Biol Blood Marrow Transplant ; 25(3): 480-487, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30423481

RESUMO

Data are limited on whether to adjust high-dose chemotherapy before autologous hematopoietic cell transplant (autoHCT) in obese patients. This study explores the effects of dose adjustment on the outcomes of obese patients, defined as body mass index (BMI) ≥ 30 kg/m2. Dose adjustment was defined as a reduction in standard dosing ≥20%, based on ideal, reported dosing and actual weights. We included 2 groups of US patients who had received autoHCT between 2008 and 2014. Specifically, we included patients with multiple myeloma (MM, n = 1696) treated with high-dose melphalan and patients with Hodgkin or non-Hodgkin lymphomas (n = 781) who received carmustine, etoposide, cytarabine, and melphalan conditioning. Chemotherapy dose was adjusted in 1324 patients (78%) with MM and 608 patients (78%) with lymphoma. Age, sex, BMI, race, performance score, comorbidity index, and disease features (stage at diagnosis, disease status, and time to transplant) were similar between dose groups. In multivariate analyses for MM, adjusting for melphalan dose and for center effect had no impact on overall survival (P = .894) and treatment-related mortality (TRM) (P = .62), progression (P = .12), and progression-free survival (PFS; P = .178). In multivariate analyses for lymphoma, adjusting chemotherapy doses did not affect survival (P = .176), TRM (P = .802), relapse (P = .633), or PFS (P = .812). No center effect was observed in lymphoma. This study demonstrates that adjusting chemotherapy dose before autoHCT in obese patients with MM and lymphoma does not influence mortality. These results do not support adjusting chemotherapy dose in this population.


Assuntos
Antineoplásicos/administração & dosagem , Cálculos da Dosagem de Medicamento , Transplante de Células-Tronco Hematopoéticas/métodos , Obesidade , Condicionamento Pré-Transplante/métodos , Adulto , Idoso , Feminino , Transplante de Células-Tronco Hematopoéticas/mortalidade , Humanos , Linfoma/tratamento farmacológico , Linfoma/mortalidade , Linfoma/terapia , Masculino , Pessoa de Meia-Idade , Mortalidade , Mieloma Múltiplo/tratamento farmacológico , Mieloma Múltiplo/mortalidade , Mieloma Múltiplo/terapia , Recidiva , Transplante Autólogo
9.
Biol Blood Marrow Transplant ; 24(2): 228-241, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28939455

RESUMO

Hematopoietic cell transplantation (HCT) is a potentially curative treatment for children and adults with malignant and nonmalignant diseases. Despite increasing survival rates, long-term morbidity after HCT is substantial. Neurocognitive dysfunction is a serious cause of morbidity, yet little is known about neurocognitive dysfunction after HCT. To address this gap, collaborative efforts of the Center for International Blood and Marrow Transplant Research and the European Society for Blood and Marrow Transplantation undertook an expert review of neurocognitive dysfunction after HCT. In this review we define what constitutes neurocognitive dysfunction, characterize its risk factors and sequelae, describe tools and methods to assess neurocognitive function in HCT recipients, and discuss possible interventions for HCT patients with this condition. This review aims to help clinicians understand the scope of this health-related problem, highlight its impact on well-being of survivors, and help determine factors that may improve identification of patients at risk for declines in cognitive functioning after HCT. In particular, we review strategies for preventing and treating neurocognitive dysfunction in HCT patients. Finally, we highlight the need for well-designed studies to develop and test interventions aimed at preventing and improving neurocognitive dysfunction and its sequelae after HCT.


Assuntos
Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Transtornos Neurocognitivos/etiologia , Biomarcadores , Humanos , Transtornos Neurocognitivos/diagnóstico , Transtornos Neurocognitivos/prevenção & controle , Transtornos Neurocognitivos/terapia , Prevalência , Fatores de Risco
10.
Biol Blood Marrow Transplant ; 22(9): 1636-1645, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27343716

RESUMO

Alternative graft sources (umbilical cord blood [UCB], matched unrelated donors [MUD], or mismatched unrelated donors [MMUD]) enable patients without a matched sibling donor to receive potentially curative hematopoietic cell transplantation (HCT). Retrospective studies demonstrate comparable outcomes among different graft sources. However, the risk and types of infections have not been compared among graft sources. Such information may influence the choice of a particular graft source. We compared the incidence of bacterial, viral, and fungal infections in 1781 adults with acute leukemia who received alternative donor HCT (UCB, n= 568; MUD, n = 930; MMUD, n = 283) between 2008 and 2011. The incidences of bacterial infection at 1 year were 72%, 59%, and 65% (P < .0001) for UCB, MUD, and MMUD, respectively. Incidences of viral infection at 1 year were 68%, 45%, and 53% (P < .0001) for UCB, MUD, and MMUD, respectively. In multivariable analysis, bacterial, fungal, and viral infections were more common after either UCB or MMUD than after MUD (P < .0001). Bacterial and viral but not fungal infections were more common after UCB than MMUD (P = .0009 and <.0001, respectively). The presence of viral infection was not associated with an increased mortality. Overall survival (OS) was comparable among UCB and MMUD patients with Karnofsky performance status (KPS) ≥ 90% but was inferior for UCB for patients with KPS < 90%. Bacterial and fungal infections were associated with poorer OS. Future strategies focusing on infection prevention and treatment are indicated to improve HCT outcomes.


Assuntos
Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Infecções/etiologia , Leucemia/complicações , Leucemia/terapia , Doença Aguda , Adolescente , Adulto , Idoso , Transplante de Células-Tronco de Sangue do Cordão Umbilical/efeitos adversos , Transplante de Células-Tronco de Sangue do Cordão Umbilical/mortalidade , Feminino , Transplante de Células-Tronco Hematopoéticas/métodos , Transplante de Células-Tronco Hematopoéticas/mortalidade , Histocompatibilidade , Humanos , Incidência , Infecções/mortalidade , Leucemia/mortalidade , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Análise de Sobrevida , Doadores não Relacionados , Adulto Jovem
11.
ACS Appl Mater Interfaces ; 7(19): 10511-7, 2015 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-25906148

RESUMO

We report an antibacterial surface that kills airborne bacteria on contact upon minutes of solar near-infrared (NIR) irradiation. This antibacterial surface employs reduced graphene oxide (rGO), a well-known near-infrared photothermal conversion agent, as the photosensitizer and is prepared by assembling oppositely charged polyelectrolyte-stabilized rGO sheets (PEL-rGO) on a quartz substrate with the layer-by-layer (LBL) technique. Upon solar irradiation, the resulting PEL-rGO LBL multilayer efficiently generates rapid localized heating and, within minutes, kills >90% airborne bacteria, including antibiotic-tolerant persisters, on contact, likely by permeabilizing their cellular membranes. The observed activity is retained even when the PEL-rGO LBL multilayer is placed underneath a piece of 3 mm thick pork tissue, indicating that solar light in the near-infrared region plays dominant roles in the observed activity. This work may pave the way toward NIR-light-activated antibacterial surfaces, and our PEL-rGO LBL multilayer may be a novel surface coating material for conveniently disinfecting biomedical implants and common objects touched by people in daily life in the looming postantibiotic era with only minutes of solar exposure.


Assuntos
Fenômenos Fisiológicos Bacterianos/efeitos da radiação , Desinfecção/métodos , Grafite/química , Grafite/efeitos da radiação , Energia Solar , Sobrevivência Celular/efeitos da radiação , Materiais Revestidos Biocompatíveis/síntese química , Materiais Revestidos Biocompatíveis/efeitos da radiação , Eletrólitos/química , Eletrólitos/efeitos da radiação , Excipientes/química , Excipientes/efeitos da radiação , Raios Infravermelhos , Teste de Materiais , Membranas Artificiais , Oxirredução/efeitos da radiação , Óxidos/química , Óxidos/efeitos da radiação , Propriedades de Superfície/efeitos dos fármacos
12.
ACS Appl Mater Interfaces ; 6(15): 13183-90, 2014 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-25026597

RESUMO

There are significant controversies on the antibacterial properties of graphene oxide (GO): GO was reported to be bactericidal in saline, whereas its activity in nutrient broth was controversial. To unveil the mechanisms underlying these contradictions, we performed antibacterial assays under comparable conditions. In saline, bare GO sheets were intrinsically bactericidal, yielding a bacterial survival percentage of <1% at 200 µg/mL. Supplementing saline with ≤10% Luria-Bertani (LB) broth, however, progressively deactivated its bactericidal activity depending on LB-supplementation ratio. Supplementation of 10% LB made GO completely inactive; instead, ∼100-fold bacterial growth was observed. Atomic force microscopy images showed that certain LB components were adsorbed on GO basal planes. Using bovine serum albumin and tryptophan as well-defined model adsorbates, we found that noncovalent adsorption on GO basal planes may account for the deactivation of GO's bactericidal activity. Moreover, this deactivation mechanism was shown to be extrapolatable to GO's cytotoxicity against mammalian cells. Taken together, our observations suggest that bare GO intrinsically kills both bacteria and mammalian cells and noncovalent adsorption on its basal planes may be a global deactivation mechanism for GO's cytotoxicity.


Assuntos
Antibacterianos/farmacologia , Grafite/química , Grafite/farmacologia , Óxidos/química , Óxidos/farmacologia , Animais , Bacillus subtilis/efeitos dos fármacos , Bovinos , Escherichia coli/efeitos dos fármacos , Células Hep G2 , Humanos , Testes de Sensibilidade Microbiana , Microscopia de Fluorescência , Soroalbumina Bovina/química , Cloreto de Sódio
13.
Chem Biol Interact ; 203(1): 38-43, 2013 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-23047027

RESUMO

Hydrolysis of acetylcholine by acetylcholinesterase (AChE) is extremely rapid, with a second-order hydrolysis rate constant k(E) (often denoted k(cat)/K(M)) that approaches 10(8) M(-1) s(-1). AChE contains a deep active site gorge with two sites of ligand binding, an acylation site (or A-site) containing the catalytic triad at the base of the gorge and a peripheral site (or P-site) near the gorge entrance. The P-site is known to contribute to catalytic efficiency with acetylthiocholine (AcSCh) by transiently trapping the substrate in a low affinity complex on its way to the A-site, where a short-lived acyl enzyme intermediate is produced. Here we ask whether the P-site does more than simply trap the substrate but in fact selectively gates entry to the A-site to provide specificity for AcSCh (and acetylcholine) relative to the close structural analogs acetyl(homo)thiocholine (Ac-hSCh, which adds one additional methylene group to thiocholine) and acetyl(nor)thiocholine (Ac-nSCh, which deletes one methylene group from thiocholine). We synthesized Ac-hSCh and Ac-nSCh and overcame technical difficulties associated with instability of the northiocholine hydrolysis product. We then compared the catalytic parameters of these substrates with AChE to those of AcSCh. Values of k(E) for Ac-hSCh and Ac-nSCh were about 2% of that for AcSCh. The k(E) for AcSCh is close to the theoretical diffusion-controlled limit for the substrate association rate constant, but kE values for Ac-hSCh or Ac-nSCh are too low to be limited by diffusion control. However, analyses of kinetic solvent isotope effects and inhibition patterns for P-site inhibitors indicate that these two analogs also do not equilibrate with the A-site prior to the initial acylation step of catalysis. We propose that kE for these substrates is partially rate-limited by a gating step that involves the movement of bound substrate from the P-site to the A-site.


Assuntos
Acetilcolinesterase/metabolismo , Acetiltiocolina/análogos & derivados , Acetilcolinesterase/química , Acetiltiocolina/química , Acetiltiocolina/metabolismo , Acilação , Domínio Catalítico , Inibidores da Colinesterase/metabolismo , Inibidores da Colinesterase/farmacologia , Proteínas Ligadas por GPI/química , Proteínas Ligadas por GPI/metabolismo , Humanos , Hidrólise , Cinética , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Especificidade por Substrato
14.
ACS Macro Lett ; 2(12): 1095-1099, 2013 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-35606973

RESUMO

Inspiration for the design of new synthetic polymers can be found in the natural world, where materials often exhibit complex properties that change depending on external stimuli. A new synthetic electroplastic elastomer hydrogel (EPEH) that undergoes changes in mechanical properties in response to both chemical and electrochemical stimuli has been prepared based on these precedents. In addition to having the capability to switch between hard and soft states, the presence of both permanent covalent and dynamic copper-based cross links also allows this stimuli-responsive material to exhibit a striking shape memory capability. The density of temporary cross links and the mechanical properties are controlled by reversible switching between the +1 and +2 oxidation states.

15.
ACS Macro Lett ; 1(1): 204-208, 2012 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-35578480

RESUMO

The dawn of the 21st century has brought with it an increasing interest in emulating the adaptive finesse of natural systems by designing materials with on-demand, tunable properties. The creation of such responsive systems could be expected, based on historical precedent, to lead to completely new engineering design paradigms. Using a bioinspired approach of coupling multiple equilibria that operate on different length scales, a material whose bulk mechanical properties can be manipulated by electrical input has been developed. The new macroscale electroplastic elastomer hydrogels can be reversibly cycled through soft and hard states while maintaining a three-dimensional shape by sequential application of oxidative and reductive potentials. This input changes the cross-linking capacity of iron ions within the gel matrix, between a poorly coordinating +2 and a more strongly binding +3 oxidation state. Inclusion of carbon nanotubes in the hydrogel preparation increases conductivity and decreases transition time.

16.
Chem Biol Drug Des ; 78(4): 495-504, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21668653

RESUMO

Protection of the enzyme acetylcholinesterase (AChE) from the toxic effects of organophosphate insecticides and chemical warfare agents (OPs) may be provided by inhibitors that bind at the peripheral binding site (P-site) near the mouth of the active-site gorge. Compounds that bind to this site may selectively block access to the acylation site (A-site) catalytic serine for OPs, but not acetylcholine itself. To identify such compounds, we employed a virtual screening approach using AutoDock 4.2 and AutoDock Vina, confirmed using compounds experimentally known to bind specifically to either the A-site or P-site. Both programs demonstrated the ability to correctly predict the binding site. Virtual screening of the NCI Diversity Set II was conducted using the apo form of the enzyme, and with acetylcholine bound at the crystallographic locations in the A-site only and in both and A- and P-sites. The docking identified 32 compounds that were obtained for testing, and one was demonstrated to bind specifically to the P-site in an inhibitor competition assay.


Assuntos
Acetilcolinesterase/metabolismo , Inibidores da Colinesterase/química , Inibidores da Colinesterase/farmacologia , Desenho de Fármacos , Acetiltiocolina/metabolismo , Sítios de Ligação , Humanos , Modelos Moleculares , Ligação Proteica , Especificidade por Substrato
17.
Chem Biol Interact ; 187(1-3): 135-41, 2010 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-20493829

RESUMO

Acetylcholinesterase (AChE) contains a narrow and deep active site gorge with two sites of ligand binding, an acylation site (or A-site) at the base of the gorge and a peripheral site (or P-site) near the gorge entrance. The P-site contributes to the catalytic efficiency of substrate hydrolysis by transiently binding substrates on their way to the acylation site, where a short-lived acyl enzyme intermediate is produced. Ligands that bind to the A-site invariably inhibit the hydrolysis of all AChE substrates, but ligands that bind to the P-site inhibit the hydrolysis of some substrates but not others. To clarify the basis of this difference, we focus here on second-order rate constants for substrate hydrolysis (k(E)), a parameter that reflects the binding of ligands only to the free form of the enzyme and not to enzyme-substrate intermediates. We first describe an inhibitor competition assay that distinguishes whether a ligand is inhibiting AChE by binding to the A-site or the P-site. We then show that the P-site-specific ligand thioflavin T inhibits the hydrolysis of the rapidly hydrolyzed substrate acetylthiocholine but fails to show any inhibition of the slowly hydrolyzed substrates ATMA (3-(acetamido)-N,N,N-trimethylanilinium) and carbachol. We derive an expression for k(E) that accounts for these observations by recognizing that the rate-limiting steps for these substrates differ. The rate-limiting step for the slow substrates is the general base-catalyzed acylation reaction k(2), a step that is unaffected by bound thioflavin T. In contrast, the rate-limiting step for acetylthiocholine is either substrate association or substrate migration to the A-site, and these steps are blocked by bound thioflavin T.


Assuntos
Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Domínio Catalítico , Inibidores da Colinesterase/metabolismo , Inibidores da Colinesterase/farmacologia , Acetiltiocolina/análogos & derivados , Acetiltiocolina/metabolismo , Animais , Benzotiazóis , Ligação Competitiva , Carbacol/análogos & derivados , Carbacol/metabolismo , Linhagem Celular , Cristalografia por Raios X , Humanos , Hidrólise/efeitos dos fármacos , Cinética , Ligantes , Compostos de Amônio Quaternário/química , Compostos de Amônio Quaternário/metabolismo , Especificidade por Substrato , Tiazóis/metabolismo , Tiazóis/farmacologia
18.
Cytometry B Clin Cytom ; 76(4): 237-48, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19382197

RESUMO

We identified CD22 expression on a blastic plasmacytoid dendritic cell (pDC) neoplasm presenting as a leukemia in a child. CD22 expression, as determined by the antibody s-HCL-1, was also noted on the neoplastic cells from three additional patients with blastic pDC tumors identified at our institution. Subsequently we determined that peripheral blood pDCs react with the s-HCL-1 antibody demonstrating that normal pDCs express CD22. Evaluation of five additional anti-CD22 antibodies indicated that staining of pDCs with these reagents was poor except for s-HCL-1. Therefore, the detection of CD22 on pDCs is best demonstrated with the use of this specific antibody clone. All anti-CD22 antibodies stained conventional DCs. We also evaluated the reactivity of the anti-CD22 antibodies with basophils and noted that the pattern of staining was similar to that seen with pDCs. The studies demonstrate that normal DCs and pDC neoplasms express CD22, and highlight clone specific differences in anti-CD22 antibody reactivity patterns on pDCs and basophils.


Assuntos
Anticorpos/imunologia , Células Sanguíneas/metabolismo , Células Dendríticas/patologia , Leucemia/patologia , Lectina 2 Semelhante a Ig de Ligação ao Ácido Siálico/metabolismo , Reações Antígeno-Anticorpo/imunologia , Células Sanguíneas/imunologia , Criança , Células Dendríticas/metabolismo , Feminino , Humanos , Leucemia/metabolismo , Lectina 2 Semelhante a Ig de Ligação ao Ácido Siálico/sangue , Lectina 2 Semelhante a Ig de Ligação ao Ácido Siálico/imunologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...