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1.
Nat Biomed Eng ; 5(8): 880-896, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34426676

RESUMO

Fibroblasts can be directly reprogrammed into cardiomyocytes, endothelial cells or smooth muscle cells. Here we report the reprogramming of mouse tail-tip fibroblasts simultaneously into cells resembling these three cell types using the microRNA mimic miR-208b-3p, ascorbic acid and bone morphogenetic protein 4, as well as the formation of tissue-like structures formed by the directly reprogrammed cells. Implantation of the formed cardiovascular tissue into the infarcted hearts of mice led to the migration of reprogrammed cells to the injured tissue, reducing regional cardiac strain and improving cardiac function. The migrated endothelial cells and smooth muscle cells contributed to vessel formation, and the migrated cardiomyocytes, which initially displayed immature characteristics, became mature over time and formed gap junctions with host cardiomyocytes. Direct reprogramming of somatic cells to make cardiac tissue may aid the development of applications in cell therapy, disease modelling and drug discovery for cardiovascular diseases.


Assuntos
Células Endoteliais/transplante , Coração/fisiologia , Infarto do Miocárdio/terapia , Miócitos de Músculo Liso/transplante , Regeneração , Animais , Ácido Ascórbico/farmacologia , Proteína Morfogenética Óssea 4/farmacologia , Reprogramação Celular/efeitos dos fármacos , Células Endoteliais/citologia , Células Endoteliais/metabolismo , Fibroblastos/citologia , Fibroblastos/metabolismo , Junções Comunicantes/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , MicroRNAs/metabolismo , Miocárdio/citologia , Miocárdio/metabolismo , Miocárdio/patologia , Miócitos de Músculo Liso/citologia , Miócitos de Músculo Liso/metabolismo , Cadeias Pesadas de Miosina/genética , Cadeias Pesadas de Miosina/metabolismo , Neovascularização Fisiológica , Transcriptoma
2.
Cardiovasc Revasc Med ; 21(2): 164-170, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32014391

RESUMO

BACKGROUND: Orbital atherectomy (OA) is an effective method of lesion preparation of severely calcified vessels prior to stent deployment. Long calcified lesions may lead to higher risk of post-procedural complications, yet the optimal treatment strategy has not been established. In this study we sought to determine the safety and efficacy of OA in patients with long (≥25-40 mm) calcified target lesions. METHODS: ORBIT II was a single-arm trial that enrolled 443 patients at 49 U.S. sites. De novo, severely calcified coronary lesions were treated with OA prior to stenting. Patients treated with the OA device were stratified into two groups according to target lesion length as visually estimated by the investigator: those with short (<25 mm; N = 314) vs. long (≥25-40 mm; N = 118) lesions. Lesions >40 mm were excluded per protocol. The primary endpoint was the 3-year major adverse cardiac event (MACE) rate, defined as a composite of cardiac death, myocardial infarction (MI), and target vessel revascularization (TVR). RESULTS: The 3-year MACE rates in patients with short (<25 mm) vs. long (≥25-40 mm) lesions were 21.1% vs. 29.9% respectively (p = 0.055). The rate of cardiac death (6.5% vs. 7.8%, p = 0.592) and TVR (8.5% vs. 13.7%, p = 0.153) did not significantly differ. The rate of MI (CK-MB > 3× ULN) at 3 years was significantly higher in patients with long (≥25-40 mm) lesions (9.0% vs. 17.0%, p = 0.024), with the majority occurring in-hospital (7.0% vs. 13.6%, p = 0.037). CONCLUSIONS: Patients with long (≥25-40 mm) calcified target lesions had similar outcomes in terms of MACE at 3 years despite higher rates of MI, which mostly occurred in-hospital. Using the more contemporary SCAI definition of MI, there was no significant difference in rates of MI between the short (<25 mm) and long (≥25-40 mm) groups. Further studies are warranted to determine how OA compares to focal force balloon angioplasty, rotational atherectomy and other novel treatment options for long severely calcified lesions. SUMMARY FOR ANNOTATED TABLE OF CONTENTS: Percutaneous coronary intervention of long calcified lesions is inherently more complex and higher risk and may require more intensive lesion preparation. This sub-analysis of ORBIT II revealed that orbital atherectomy treatment of longer (≥25-40 mm) lesions was associated with a higher rate of MACE at 30 days, but not at 3 years. This difference, however, was driven primarily by a higher in-hospital non-Q-wave MI rate; using the more contemporary SCAI definition of MI, there was no significant difference in rates of MI between the short (<25 mm) and long (≥25-40 mm) groups.


Assuntos
Aterectomia Coronária , Doença da Artéria Coronariana/terapia , Intervenção Coronária Percutânea , Calcificação Vascular/terapia , Idoso , Idoso de 80 Anos ou mais , Aterectomia Coronária/efeitos adversos , Aterectomia Coronária/mortalidade , Doença da Artéria Coronariana/diagnóstico por imagem , Doença da Artéria Coronariana/mortalidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/mortalidade , Intervenção Coronária Percutânea/efeitos adversos , Intervenção Coronária Percutânea/instrumentação , Intervenção Coronária Percutânea/mortalidade , Estudos Prospectivos , Medição de Risco , Fatores de Risco , Índice de Gravidade de Doença , Stents , Fatores de Tempo , Resultado do Tratamento , Estados Unidos , Calcificação Vascular/diagnóstico por imagem , Calcificação Vascular/mortalidade
3.
J Leukoc Biol ; 105(6): 1225-1234, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30907983

RESUMO

Neutrophil extracellular traps (NETs) are implicated in autoimmune, thrombotic, malignant, and inflammatory diseases; however, little is known of their endogenous regulation under basal conditions. Inflammatory effects of neutrophils are modulated by extracellular purines such as adenosine (ADO) that is inhibitory or ATP that generally up-regulates effector functions. In order to evaluate the effects of ADO on NETs, human neutrophils were isolated from peripheral venous blood from healthy donors and stimulated to make NETs. Treatment with ADO inhibited NET production as quantified by 2 methods: SYTOX green fluorescence and human neutrophil elastase (HNE)-DNA ELISA assay. Specific ADO receptor agonist and antagonist were tested for their effects on NET production. The ADO 2A receptor (A2A R) agonist CSG21680 inhibited NETs to a similar degree as ADO, whereas the A2A R antagonist ZM241385 prevented ADO's NET-inhibitory effects. Additionally, CD73 is a membrane bound ectonucleotidase expressed on mesenchymal stromal cells (MSCs) that allows manipulation of extracellular purines in tissues such as bone marrow. The effects of MSCs on NET formation were evaluated in coculture. MSCs reduced NET formation in a CD73-dependent manner. These results imply that extracellular purine balance may locally regulate NETosis and may be actively modulated by stromal cells to maintain tissue homeostasis.


Assuntos
Adenosina/imunologia , Armadilhas Extracelulares/imunologia , Neutrófilos/imunologia , 5'-Nucleotidase/imunologia , Técnicas de Cocultura , Proteínas Ligadas por GPI/imunologia , Humanos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/imunologia , Neutrófilos/citologia , Receptor A2A de Adenosina/imunologia
4.
Circ Arrhythm Electrophysiol ; 11(5): e006408, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29748197

RESUMO

BACKGROUND: Atrial fibrillation (AF) is the most common cardiac arrhythmia. Although treatment options for AF exist, many patients cannot be maintained in normal sinus rhythm. Amiodarone is an effective medication for AF but has limited clinical utility because of off-target tissue toxicity. METHODS: Here, we use a pig model of AF to test the efficacy of an amiodarone-containing polyethylene glycol-based hydrogel. The gel is placed directly on the atrial epicardium through the pericardial space in a minimally invasive procedure using a specially designed catheter. RESULTS: Implantation of amiodarone-containing gel significantly reduced the duration of sustained AF at 21 and 28 days; inducibility of AF was reduced 14 and 21 days post-delivery. Off-target organ drug levels in the liver, lungs, thyroid, and fat were significantly reduced in animals treated with epicardial amiodarone gel compared with systemic controls in small-animal distribution studies. CONCLUSIONS: The pericardium is an underutilized therapeutic site and may be a new treatment strategy for AF and other cardiovascular diseases.


Assuntos
Amiodarona/administração & dosagem , Antiarrítmicos/administração & dosagem , Fibrilação Atrial/prevenção & controle , Portadores de Fármacos , Frequência Cardíaca/efeitos dos fármacos , Pericárdio/efeitos dos fármacos , Polietilenoglicóis/química , Amiodarona/química , Amiodarona/toxicidade , Animais , Antiarrítmicos/química , Antiarrítmicos/toxicidade , Fibrilação Atrial/fisiopatologia , Modelos Animais de Doenças , Composição de Medicamentos , Implantes de Medicamento , Liberação Controlada de Fármacos , Hidrogéis , Masculino , Pericárdio/fisiopatologia , Ratos Sprague-Dawley , Sus scrofa , Fatores de Tempo
5.
J Am Heart Assoc ; 7(8)2018 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-29650707

RESUMO

BACKGROUND: With the recent implementation of the Medicare Quality Payment Program, providers face increasing accountability for delivering high-quality care. Such pay-for-performance programs aim to leverage systematic data captured by electronic health record (EHR) systems to measure performance; however, the fidelity of EHR query for assessing performance has not been validated compared with manual chart review. We sought to determine whether our institution's methodology of EHR query could accurately identify cases in which providers failed to prescribe statins for eligible patients with coronary artery disease. METHODS AND RESULTS: A total of 9459 patients with coronary artery disease were seen at least twice at the Emory Clinic between July 2014 and June 2015, of whom 1338 (14.1%, 95% confidence interval 13.5-14.9%) had no statin prescription or exemption per EHR query. A total of 120 patient cases were randomly selected and reviewed by 2 physicians for further adjudication. Of the 120 cases initially classified as statin prescription failures, only 21 (17.5%; 95% confidence interval, 11.7-25.3%) represented true failure following physician review. CONCLUSIONS: Sole reliance on EHR data query to measure quality metrics may lead to significant errors in assessing provider performance. Institutions should be cognizant of these potential sources of error, provide support to medical providers, and form collaborative data management teams to promote and improve meaningful use of EHRs. We propose actionable steps to improve the accuracy of EHR data query that require hypothesis testing and prospective validation in future studies.


Assuntos
Centros Médicos Acadêmicos , Doença da Artéria Coronariana/tratamento farmacológico , Prescrições de Medicamentos/estatística & dados numéricos , Registros Eletrônicos de Saúde/estatística & dados numéricos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Erros de Medicação/estatística & dados numéricos , Idoso , Feminino , Seguimentos , Georgia , Humanos , Masculino , Estudos Prospectivos
6.
J Am Heart Assoc ; 7(2)2018 01 13.
Artigo em Inglês | MEDLINE | ID: mdl-29331956

RESUMO

BACKGROUND: During myocardial ischemia/reperfusion (MI/R) injury, there is extensive release of immunogenic metabolites that activate cells of the innate immune system. These include ATP and AMP, which upregulate chemotaxis, migration, and effector function of early infiltrating inflammatory cells. These cells subsequently drive further tissue devitalization. Mesenchymal stromal cells (MSCs) are a potential treatment modality for MI/R because of their powerful anti-inflammatory capabilities; however, the manner in which they regulate the acute inflammatory milieu requires further elucidation. CD73, an ecto-5'-nucleotidase, may be critical in regulating inflammation by converting pro-inflammatory AMP to anti-inflammatory adenosine. We hypothesized that MSC-mediated conversion of AMP into adenosine reduces inflammation in early MI/R, favoring a micro-environment that attenuates excessive innate immune cell activation and facilitates earlier cardiac recovery. METHODS AND RESULTS: Adult rats were subjected to 30 minutes of MI/R injury. MSCs were encapsulated within a hydrogel vehicle and implanted onto the myocardium. A subset of MSCs were pretreated with the CD73 inhibitor, α,ß-methylene adenosine diphosphate, before implantation. Using liquid chromatography/mass spectrometry, we found that MSCs increase myocardial adenosine availability following injury via CD73 activity. MSCs also reduce innate immune cell infiltration as measured by flow cytometry, and hydrogen peroxide formation as measured by Amplex Red assay. These effects were dependent on MSC-mediated CD73 activity. Finally, through echocardiography we found that CD73 activity on MSCs was critical to optimal protection of cardiac function following MI/R injury. CONCLUSIONS: MSC-mediated conversion of AMP to adenosine by CD73 exerts a powerful anti-inflammatory effect critical for cardiac recovery following MI/R injury.


Assuntos
Adenosina/metabolismo , Imunidade Inata , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/metabolismo , Infarto do Miocárdio/cirurgia , Traumatismo por Reperfusão Miocárdica/cirurgia , Miocárdio/metabolismo , Tecidos Suporte , 5'-Nucleotidase/antagonistas & inibidores , 5'-Nucleotidase/metabolismo , Difosfato de Adenosina/análogos & derivados , Difosfato de Adenosina/farmacologia , Monofosfato de Adenosina/metabolismo , Animais , Células Cultivadas , Técnicas de Cocultura , Modelos Animais de Doenças , Inibidores Enzimáticos/farmacologia , Proteínas Ligadas por GPI/antagonistas & inibidores , Proteínas Ligadas por GPI/metabolismo , Humanos , Peróxido de Hidrogênio/metabolismo , Masculino , Células-Tronco Mesenquimais/efeitos dos fármacos , Infarto do Miocárdio/imunologia , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/fisiopatologia , Traumatismo por Reperfusão Miocárdica/imunologia , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Miocárdio/imunologia , Miocárdio/patologia , Neutrófilos/imunologia , Neutrófilos/metabolismo , Ratos Sprague-Dawley , Recuperação de Função Fisiológica , Nicho de Células-Tronco
7.
Nat Commun ; 6: 7792, 2015 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-26242746

RESUMO

Macrophages are an essential component of the immune response to ischaemic injury and play an important role in promoting inflammation and its resolution, which is necessary for tissue repair. The type I transmembrane glycoprotein CD163 is exclusively expressed on macrophages, where it acts as a receptor for haemoglobin:haptoglobin complexes. An extracellular portion of CD163 circulates in the blood as a soluble protein, for which no physiological function has so far been described. Here we show that during ischaemia, soluble CD163 functions as a decoy receptor for TWEAK, a secreted pro-inflammatory cytokine of the tumour necrosis factor family, to regulate TWEAK-induced activation of canonical nuclear factor-κB (NF-κB) and Notch signalling necessary for myogenic progenitor cell proliferation. Mice with deletion of CD163 have transiently elevated levels of TWEAK, which stimulate muscle satellite cell proliferation and tissue regeneration in their ischaemic and non-ischaemic limbs. These results reveal a role for soluble CD163 in regulating muscle regeneration after ischaemic injury.


Assuntos
Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Macrófagos/fisiologia , Músculo Esquelético/fisiologia , Receptores de Superfície Celular/metabolismo , Regeneração , Fatores de Necrose Tumoral/metabolismo , Animais , Citocina TWEAK , Masculino , Camundongos Knockout , NF-kappa B/metabolismo , Distribuição Aleatória , Receptores Notch/metabolismo , Traumatismo por Reperfusão
8.
Atherosclerosis ; 241(2): 692-700, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26125411

RESUMO

OBJECTIVES: Toll-like Receptor 4 (TLR4) is implicated in modulating inflammatory cytokines though its role in atherosclerosis remains uncertain. We have recently described a non-foam cell macrophage phenotype driven by ingestion of hemoglobin:haptoglobin complexes (HH), via the scavenger receptor CD163, characterized by reduced inflammatory cytokine production. In this study, we examined the role of iron metabolism in modulating TLR4 signaling in these cells. METHODS AND RESULTS: Areas in human atherosclerotic plaque with non-foam cell, CD163 positive macrophages demonstrated reduced expression of tumor necrosis factor alpha (TNF-α) and interferon-beta (INF-ß) compared to foam cells. Human macrophages differentiated in hemoglobin:haptoglobin (HH) complexes expressed the CD163 positive non-foam cell phenotype and demonstrated significantly less TNF-α and INF-ß compared to control macrophages when exposed to oxidized LDL (oxLDL) or lipopolysaccharide (LPS). LPS stimulated expression of TNF-α and INF-ß could be restored in HH macrophages by pretreatment with hepcidin, an endogenous suppressor of ferroportin1 (FPN), or by genetic suppression of FPN in macrophages derived from myeloid specific FPN knockout mice. LPS stimulated control macrophages demonstrated increase in TLR4 trafficking to lipid rafts; this response was suppressed in HH macrophages but was restored upon pretreatment with hepcidin. Using a pharmacologic hepcidin suppressor, we observed a decrease in cytokine expression and TLR4-lipid raft trafficking in LPS-stimulated in a murine macrophage model. CONCLUSION: TLR4 dependent macrophage signaling is controlled via hepcidin-ferroportin1 axis by influencing TLR4-lipid raft interactions. Pharmacologic manipulation of iron metabolism may represent a promising approach to limiting TLR4-mediated inflammatory responses.


Assuntos
Proteínas de Transporte de Cátions/metabolismo , Hepcidinas/química , Macrófagos/citologia , Placa Aterosclerótica/metabolismo , Receptor 4 Toll-Like/metabolismo , Animais , Antígenos CD/metabolismo , Antígenos de Diferenciação Mielomonocítica/metabolismo , Células Espumosas/citologia , Haptoglobinas/química , Hemoglobinas/química , Humanos , Inflamação , Ferro/química , Lipopolissacarídeos/química , Lipoproteínas LDL/química , Macrófagos/metabolismo , Macrófagos Peritoneais/metabolismo , Masculino , Microdomínios da Membrana/química , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fator 88 de Diferenciação Mieloide/metabolismo , Receptores de Superfície Celular/metabolismo , Transdução de Sinais , Receptor 4 Toll-Like/genética , Fator de Necrose Tumoral alfa/metabolismo
9.
Am J Physiol Gastrointest Liver Physiol ; 298(6): G1004-12, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20224005

RESUMO

Ethanol treatment of cultured hepatoma cells and of mice inhibited the activity of AMP-activated protein kinase (AMPK). This study shows that the inhibitory effect of ethanol on AMPK phosphorylation is exerted through the inhibition of the phosphorylation of upstream kinases and the activation of protein phosphatase 2A (PP2A).Inhibition of AMPK phosphorylation by palmitate was attributed to ceramide-dependent PP2A activation. We hypothesized that the inhibitory effect of ethanol on AMPK phosphorylation was mediated partly through the generation of ceramide. The effect of ethanol and inhibitors of ceramide synthesis on AMPK phosphorylation, ceramide levels, and PP2A activity were assessed in rat hepatoma cells (H4IIEC3). The effect of ethanol on hepatic ceramide levels was also studied in C57BL/6J mice fed the Lieber-DeCarli diet. In H4IIEC3 cells, ceramide reduced AMPK phosphorylation when they were treated for between 4 and 12 h. The basal level of AMPK phosphorylation in hepatoma cells was increased with the treatment of ceramide synthase inhibitor, fumonisin B1. Ethanol treatment significantly increased cellular ceramide content and PP2A activity by approximately 18-23%, when the cells were treated with ethanol for between 4 and 12 h. These changes in intracellular ceramide concentrations and PP2A activity correlated with the time course over which ethanol inhibited AMPK phosphorylation. The activation of PP2A and inhibition of AMPK phosphorylation caused by ethanol was attenuated by fumonisin B1 and imipramine, an acid sphingomyelinase (SMase) inhibitor. There was a significant increase in the levels of ceramide and acid SMase mRNA in the livers of ethanol-fed mice compared with controls. We concluded that the effect of ethanol on AMPK appears to be mediated in part through increased cellular levels of ceramide and activation of PP2A.


Assuntos
Adenilato Quinase/metabolismo , Ceramidas/metabolismo , Etanol/toxicidade , Compostos de Anilina , Animais , Compostos de Benzilideno , Linhagem Celular , Dieta , Ácidos Graxos Monoinsaturados , Fumonisinas , Regulação da Expressão Gênica/efeitos dos fármacos , Peróxido de Hidrogênio , Imipramina , Masculino , Camundongos , Fosforilação , Proteína Fosfatase 2/genética , Proteína Fosfatase 2/metabolismo , Ratos
10.
Ann Biomed Eng ; 37(10): 2003-17, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19267201

RESUMO

Parylene is a biologically inert material capable of being deposited in conformal nanoscale layers on virtually any surface, making it a viable structural material for the fabrication of drug delivery devices, as well as implant coatings, sensors, and other biomedical technologies. Here we explore its novel drug delivery applications by using parylene to package the polymethyloxazoline-polydimethylsiloxane-polymethyloxazoline (PMOXA-PDMS-PMOXA) block copolymer membrane of a nanoscale thickness (approximately 4 nm/layer) mixed with a therapeutic element, creating an active parylene-encapsulated copolymeric (APC) membrane for slow release drug delivery of dexamethasone (Dex), a potent anti-inflammatory and immunosuppressant synthetic glucocorticoid. Given current needs for localized therapeutic release for conditions such as cancer, post-surgical inflammation, wound healing, regenerative medicine, to name a few, this stand-alone and minimally invasive implantable technology may impact a broad range of medical scenarios. To evaluate the applicability of the APC membrane as a biocompatible drug delivery system, real-time polymerase chain reaction (RT-PCR) was performed to investigate the expression of cytokines that regulate cellular stress and inflammation as a result of in vitro RAW264.7 macrophage cell growth on the APC membrane. Significant decreases in relative mRNA levels of IL-6, TNF-alpha, and iNOS were observed. Dex functionalized APC membranes were further found to effectively slow-elute the drug via confocal microscopy, with a confirmed extended elution capability over a period of several days, undergoing phosphate buffered saline washes between time points. In addition, we examined the membrane surface through atomic force microscopy (AFM) to examine Dex/copolymer deposition, and to characterize the surface of the APC membrane. Furthermore, we evaluated the effects of incubation with the APC membrane in solution on macrophage growth behavior and cellular adhesion, including the physical properties of parylene and the copolymer to elucidate the anti-adhesive responses we observed. The results of this study will provide insight into ultra-thin and flexible devices of parylene-encapsulated copolymer membranes as platform drug delivery technologies capable of localized and precision therapeutic drug elution.


Assuntos
Preparações de Ação Retardada/administração & dosagem , Preparações de Ação Retardada/química , Membranas Artificiais , Nanoestruturas/administração & dosagem , Nanoestruturas/química , Polímeros/química , Xilenos/química , Nanoestruturas/ultraestrutura , Tamanho da Partícula
11.
JALA Charlottesv Va ; 13(4): 206-214, 2008 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-25892972

RESUMO

Amphiphilic block copolymers are finding increased potential in biological and medical research due to their innate alternating hydrophilic and hydrophilic blocks/segments which can be used to package therapeutics, or coat a broad array of biological interfaces. Some studies are already directed towards utilizing these copolymers' ability to form micelles or vesicles to develop novel methods of drug delivery to prevent inflammation or pro-cancer activity. Our study, however, aims to investigate the more fundamental cell-block copolymer interaction for use in protective nanofilms to prevent bio-fouling of non-tissue based implantable devices. Block copolymers could potentially fill the demand for biologically inert, highly functionalizable biomaterials desirable for this type of application. Two such polymers used in our study include PMOXA-PDMS-PMOXA triblock copolymer and PEO/PMMA diblock copolymer. Each block copolymer possesses hydrophilic and hydrophobic blocks that enable it to mimic the cell lipid membrane. So far we have shown that triblock copolymer is capable of inhibiting the accumulation of murine macrophages onto glass substrates. Preliminary evidence has suggested that the triblock copolymer has anti-adsorptive as well as non-inflammatory capabilities during short incubation periods (7 days) in vitro. While the diblock copolymer displays minimal anti-adsorptive activities, nanofilms comprised of a mixture of the two copolymers were able to significantly reduce macrophage accumulation onto glass substrates. The disparate behavior seen by macrophages on the different materials may be due to specific inherent properties such as preference for hydrophobic vs. hydrophilic surfaces and/or rough vs. smooth nano-textures. Furthermore, the specific end groups of the two polymers may exhibit varying capacities to resisting non-specific protein adsorption. Continued investigation outlining the physical and chemical properties desirable for an anti-adsorptive nano-film coating will serve as a basis upon which to design durable implant-tissue interfaces that can react to various external stimuli.

12.
Gastroenterology ; 128(5): 1340-53, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15887116

RESUMO

BACKGROUND & AIMS: Our understanding of the intestinotropic actions of glucagon-like peptide-2 (GLP-2)(1-33) is based on pharmacologic studies involving exogenous administration. However, the physiologic role of GLP-2 in mucosal growth and adaptation to nutritional stimulation remains poorly understood. METHODS: The properties of GLP-2(3-33), a GLP-2(1-33) metabolite, were determined in baby-hamster kidney cells transfected with the mouse GLP-2 receptor complementary DNA and in isolated murine intestinal muscle strips. To investigate the role of endogenous GLP-2(1-33) in gut adaptation, GLP-2(3-33) was administered to mice that were re-fed for 24 hours after 24 hours of fasting, and the small intestine was analyzed. GLP-2(3-33) also was injected into rats for analysis of circulating GLP-2(1-33) levels. RESULTS: GLP-2(3-33) antagonized the actions of GLP-2(1-33) in vitro and ex vivo. Fasting mice exhibited small intestinal atrophy (37% +/- 1% decrease in small intestinal weight, 19% +/- 2% decrease in crypt-villus height, and 99% +/- 35% increase in villus apoptosis, P < .05-.01). Adaptive growth in re-fed mice restored all these parameters, as well as crypt-cell proliferation, to normal control levels (P < .05 vs. fasting); these adaptive changes were prevented partially or completely by co-administration of GLP-2(3-33) to refeeding mice (by 32% +/- 19% to 103% +/- 15%, P < .05-.01 vs re-fed mice). Exogenous GLP-2(3-33) did not affect endogenous GLP-2(1-33) levels. CONCLUSIONS: These data show that endogenous GLP-2 regulates the intestinotropic response in re-fed mice through modulation of crypt-cell proliferation and villus apoptosis. GLP-2 is therefore a physiologic regulator of the dynamic adaptation of the gut mucosal epithelium in response to luminal nutrients.


Assuntos
Adaptação Fisiológica/fisiologia , Ingestão de Alimentos/fisiologia , Mucosa Intestinal/fisiologia , Fragmentos de Peptídeos/fisiologia , Adaptação Fisiológica/efeitos dos fármacos , Sequência de Aminoácidos , Animais , Apoptose/fisiologia , Peso Corporal , Divisão Celular/fisiologia , Clonagem Molecular , Ingestão de Líquidos/fisiologia , Feminino , Expressão Gênica , Glucagon/genética , Peptídeo 2 Semelhante ao Glucagon , Receptor do Peptídeo Semelhante ao Glucagon 1 , Peptídeos Semelhantes ao Glucagon , Mucosa Intestinal/citologia , Mucosa Intestinal/enzimologia , Intestino Delgado/citologia , Intestino Delgado/enzimologia , Intestino Delgado/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Tamanho do Órgão , Fragmentos de Peptídeos/sangue , Fragmentos de Peptídeos/farmacologia , Proglucagon , Precursores de Proteínas/genética , Ratos , Ratos Wistar , Receptores de Glucagon/genética , Receptores de Glucagon/metabolismo
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