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1.
Gen Hosp Psychiatry ; 86: 50-55, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38070241

RESUMO

BACKGROUND: There is currently an increasing recognition of and focus on structural and institutional racism and its impacts on health disparities. In psychiatry and mental health, research has focused on racial and ethnic disparities in the availability and utilization of mental health services, care in emergency departments, and inpatient psychiatric services. Little is known about disparities in care on general hospital psychiatry consultation-liaison (CL) services. METHODS: In this exploratory study, we conducted a retrospective chart review using electronic health record (EHR) data of all adults (≥ 18 years of age) admitted to inpatient medical or surgical floors at an urban academic medical center for whom a psychiatric consultation was requested during the study period. We examined differences by race and ethnicity in: rates of consultation requests; use of legal holds, constant observation, restraints; follow-up by the CL service; and ultimate disposition. RESULTS: The service received 310 unique consults during the study period. Compared to hospital-wide numbers, Black-identifying patients were over-represented in our sample (11.9% vs 6.6%), while Latinx patients were underrepresented (6.1% vs 9.8%). Of the clinical and outcome variables collected, there were higher odds of being placed on a legal hold both prior to (OR 2.6) and after the consult question (OR 2.98) and in the odds of having a one-to-one observer prior to (OR 2.47) and after (OR 2.9) the initial consult visit for Black-identifying patients, when adjusting for confounders. There were no other measurable differences in care or outcomes by racial or ethnic categories. CONCLUSION: Black-identifying patients may be more likely to receive psychiatric consultation and be placed on legal holds because of a combination of chronic adverse social determinants of health and race-based bias. Conversely, Latinx patients may be less likely to receive psychiatric consultation because of language barriers among other factors. The lack of disparities identified in other domains may be encouraging, but larger studies are needed. Further research is also needed to identify causality and interventions that could help close the gap in care and outcomes for racial and ethnic minorities.


Assuntos
Centros Médicos Acadêmicos , Etnicidade , Adulto , Humanos , Estudos Retrospectivos , Hospitais , Encaminhamento e Consulta
2.
Breast Cancer Res Treat ; 198(2): 383-390, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36689092

RESUMO

PURPOSE: Disseminated tumor cells (DTCs) expressing epithelial markers in the bone marrow are associated with recurrence and death, but little is known about risk factors predicting their occurrence. We detected EPCAM+/CD45- cells in bone marrow from early stage breast cancer patients after neoadjuvant chemotherapy (NAC) in the I-SPY 2 Trial and examined clinicopathologic factors and outcomes. METHODS: Patients who signed consent for SURMOUNT, a sub-study of the I-SPY 2 Trial (NCT01042379), had bone marrow collected after NAC at the time of surgery. EPCAM+CD45- cells in 4 mLs of bone marrow aspirate were enumerated using immunomagnetic enrichment/flow cytometry (IE/FC). Patients with > 4.16 EPCAM+CD45- cells per mL of bone marrow were classified as DTC-positive. Tumor response was assessed using the residual cancer burden (RCB), a standardized approach to quantitate the extent of residual invasive cancer present in the breast and the axillary lymph nodes after NAC. Association of DTC-positivity with clinicopathologic variables and survival was examined. RESULTS: A total of 73 patients were enrolled, 51 of whom had successful EPCAM+CD45- cell enumeration. Twenty-four of 51 (47.1%) were DTC-positive. The DTC-positivity rate was similar across receptor subtypes, but DTC-positive patients were significantly younger (p = 0.0239) and had larger pretreatment tumors compared to DTC-negative patients (p = 0.0319). Twenty of 51 (39.2%) achieved a pathologic complete response (pCR). While DTC-positivity was not associated with achieving pCR, it was significantly associated with higher RCB class (RCB-II/III, 62.5% vs. RCB-0/I; 33.3%; Chi-squared p = 0.0373). No significant correlation was observed between DTC-positivity and distant recurrence-free survival (p = 0.38, median follow-up = 3.2 years). CONCLUSION: DTC-positivity at surgery after NAC was higher in younger patients, those with larger tumors, and those with residual disease at surgery.


Assuntos
Neoplasias da Mama , Humanos , Feminino , Neoplasias da Mama/patologia , Medula Óssea/patologia , Molécula de Adesão da Célula Epitelial/uso terapêutico , Terapia Neoadjuvante , Citometria de Fluxo , Prognóstico
3.
Artigo em Inglês | MEDLINE | ID: mdl-35948255

RESUMO

BACKGROUND: Delirium is common in the setting of infection with severe acute respiratory syndrome coronavirus 2. Anecdotal evidence and case reports suggest that patients with delirium in the setting of Coronavirus 2019 (COVID-19) may exhibit specific features, including increased tone, abulia, and alogia. OBJECTIVE: To determine whether differences exist in sociodemographic and medical characteristics, physical examination findings, and medication use in delirious patients with and without COVID-19 infection referred for psychiatric consultation. METHODS: We undertook an exploratory, retrospective chart review of 486 patients seen by the psychiatry consultation service at a tertiary care hospital from March 10 to May 15, 2020. Delirious patients were diagnosed via clinical examination by a psychiatric consultant, and these patients were stratified by COVID-19 infection status. The strata were described and compared using bivariate analyses across sociodemographic, historical, objective, and treatment-related variables. RESULTS: A total of 109 patients were diagnosed with delirium during the study period. Thirty-six were COVID-19+. Median age was 63 years and did not differ between groups. COVID-19+ patients with delirium were more likely to present from nursing facilities (39% vs 11%; Fisher's exact test; P = 0.001) and have a history of schizophrenia (11% vs 0%; Fisher's exact test; P = 0.011). Myoclonus (28% vs 4%; P = 0.002), hypertonia (36% vs 10%; P = 0.003), withdrawal (36% vs 15%; P = 0.011), akinesia (19% vs 6%; P = 0.034), abulia (19% vs 3%; P = 0.004), and alogia (25% vs 8%; P = 0.012) were more common in COVID-19+ patients. COVID-19+ delirious patients were significantly more likely to have received ketamine (28% vs 7%; P = 0.006), alpha-adrenergic agents besides dexmedetomidine (36% vs 14%; P = 0.014), and enteral antipsychotics (92% vs 66%; P = 0.007) at some point. CONCLUSIONS: Patients with COVID-19 delirium referred for psychiatric consultation are more likely to reside in nursing facilities and have a history of schizophrenia than delirious patients without COVID-19. Patients with delirium in the setting of COVID-19 may exhibit features consistent with akinetic mutism. Psychiatrists must assess for such features, as they may influence management choices and the risk of side effects with agents commonly used in the setting of delirium.


Assuntos
COVID-19 , Delírio , Humanos , Pessoa de Meia-Idade , Estudos Retrospectivos , Delírio/tratamento farmacológico , Delírio/epidemiologia , Delírio/diagnóstico , SARS-CoV-2 , Demografia
4.
Mob DNA ; 13(1): 22, 2022 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-36068622

RESUMO

BACKGROUND: Bats are a major reservoir of zoonotic viruses, and there has been growing interest in characterizing bat-specific features of innate immunity and inflammation. Recent studies have revealed bat-specific adaptations affecting interferon (IFN) signaling and IFN-stimulated genes (ISGs), but we still have a limited understanding of the genetic mechanisms that have shaped the evolution of bat immunity. Here we investigated the transcriptional and epigenetic dynamics of transposable elements (TEs) during the type I IFN response in little brown bat (Myotis lucifugus) primary embryonic fibroblast cells, using RNA-seq and CUT&RUN. RESULTS: We found multiple bat-specific TEs that undergo both locus-specific and family-level transcriptional induction in response to IFN. Our transcriptome reassembly identified multiple ISGs that have acquired novel exons from bat-specific TEs, including NLRC5, SLNF5 and a previously unannotated isoform of the IFITM2 gene. We also identified examples of TE-derived regulatory elements, but did not find strong evidence supporting genome-wide epigenetic activation of TEs in response to IFN. CONCLUSION: Collectively, our study uncovers numerous TE-derived transcripts, proteins, and alternative isoforms that are induced by IFN in Myotis lucifugus cells, highlighting candidate loci that may contribute to bat-specific immune function.

5.
Cureus ; 13(1): e12686, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33598375

RESUMO

Cranial epidural hematoma is a serious event requiring immediate intervention. This can be due to sudden traction tearing the vessels between the dura and the skull. During posterior fossa surgery, brain collapse may emerge due to the sudden reduction of prolonged elevated intracranial pressure; it could cause dura-skull detachment to create epidural hematoma even far from the surgical site. Hence, we should be aware of this complication when approaching posterior fossa tumors as it frequently leads to severe neurologic impairment or death. Here, we report a 12-year old previously healthy child who was admitted with a 4-month history of severe headache, vomiting, and right eye blindness due to increased intracranial pressure. A brain Computed Tomography (CT) scan showed obstructive hydrocephalus, and contrast-enhanced Magnetic Resonance Imaging (MRI) confirmed intraventricular posterior fossa tumor. After tumor resection, the patient developed an epidural hematoma far from the surgery site. Removal of the hematoma exposed lacerations of superior sagittal sinus due to dural detachment. Failure to control intracranial pressure resulted in a fatal outcome.

6.
PLoS One ; 14(10): e0223670, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31600354

RESUMO

The Escherichia coli's membrane protein OmpA has been identified as a potential biosurfactant due to their amphiphilic nature, and their capacity to stabilize emulsions of dodecane in water. In this study, the influence of surfactant type, concentration, preservation time and droplet size on the crystallization of n-dodecane and water, in oil-in-water emulsions stabilized with six rationally designed Escherichia coli's OmpA-based peptides was investigated. A differential scanning calorimetry (DSC) protocol was established using emulsions stabilized with Tween 20® and Tween 80®. A relationship between the surfactant concentration and the crystallization temperatures of n-dodecane and water was observed, where the crystallization temperatures seem to be dependent on the preservation time. A deconvolution analysis shows that the peak morphology possibly depends on the interactions at the interface because the enthalpic contributions of each Gaussian peak remained similar in emulsions stabilized with the same peptide. Adsorption results show that the main driver for adsorption and thus stabilization of emulsions is polar interactions (e.g. H-bonding) through the hydrophilic parts of the peptides. Those peptides with a preponderance of polar interaction groups distribution (i.e. NH2, COOH, imidazole) showed the highest interfacial activity under favorable pH conditions. This suggests that custom-made peptides whose hydrophilic/hydrophobic regions can be fine-tuned depending on the application can be easily produced with the additional advantage of their biodegradable nature.


Assuntos
Alcanos/química , Proteínas da Membrana Bacteriana Externa/farmacologia , Peptídeos/farmacologia , Água/química , Adsorção , Sequência de Aminoácidos , Proteínas da Membrana Bacteriana Externa/química , Cristalização , Emulsões/química , Interações Hidrofóbicas e Hidrofílicas , Peptídeos/química , Tensão Superficial , Temperatura
7.
Methods Mol Biol ; 1634: 203-210, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28819853

RESUMO

Enumerating circulating tumor cells (CTCs) in blood and disseminated tumor cells (DTCs) in bone marrow has shown to be clinically useful, as elevated numbers of these cells predict poor clinical outcomes. Accurate detection and quantification is, however, difficult and technically challenging because CTCs and DTCs are extremely rare. We have developed a novel quantitative detection method for enumeration of CTCs and DTCs. Our approach consists of two steps: (1) EPCAM-based immunomagnetic enrichment followed by (2) flow cytometry (IE/FC). The assay takes approximately 2 h to complete. In addition to tumor cell enumeration, IE/FC offers opportunities for direct isolation of highly pure tumor cells for downstream molecular characterization.


Assuntos
Citometria de Fluxo/métodos , Separação Imunomagnética/métodos , Nanopartículas de Magnetita/química , Neoplasias/diagnóstico , Células Neoplásicas Circulantes/patologia , Anticorpos Monoclonais/química , Anticorpos Monoclonais/metabolismo , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/imunologia , Biomarcadores Tumorais/metabolismo , Células da Medula Óssea/imunologia , Células da Medula Óssea/metabolismo , Células da Medula Óssea/patologia , Contagem de Células/instrumentação , Contagem de Células/métodos , Linhagem Celular Tumoral , Molécula de Adesão da Célula Epitelial/genética , Molécula de Adesão da Célula Epitelial/imunologia , Molécula de Adesão da Célula Epitelial/metabolismo , Desenho de Equipamento , Citometria de Fluxo/instrumentação , Corantes Fluorescentes/química , Humanos , Imunoconjugados/química , Separação Imunomagnética/instrumentação , Antígenos Comuns de Leucócito/genética , Antígenos Comuns de Leucócito/imunologia , Antígenos Comuns de Leucócito/metabolismo , Neoplasias/sangue , Neoplasias/imunologia , Neoplasias/patologia , Células Neoplásicas Circulantes/imunologia , Células Neoplásicas Circulantes/metabolismo , Ligação Proteica
8.
Surg Case Rep ; 2(1): 80, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27495992

RESUMO

A wandering liver is a rare development in both the adult and pediatric population where the liver is freely displaced along a transverse axis. We describe the first known occurrence in published literature of a wandering liver in an adult individual who also had an intestinal malrotation complicated by a midgut volvulus. The abnormal ability for a liver to wander presents a highly unusual anatomy that can be disorienting. Laparoscopic surgery is a viable option in reducing a midgut volvulus and addressing an intestinal malrotation in the presence of a wandering liver. This unusual presentation educates clinicians to avoid potential misdiagnosis given the abnormal location of the duodenum, appendix, liver, and gallbladder.

9.
Cambios rev. méd ; 15(1): 67-69, ene. - 2016. ilus
Artigo em Espanhol | LILACS | ID: biblio-1008566

RESUMO

Introducción: Los traumatismos craneoencefálicos penetrantes son cada vez más frecuentes en la sociedad actual, por lo que el neurocirujano debe estar preparado para atenderlas, siguiendo las guías y recomendaciones para su manejo. Caso: Paciente masculino joven, quien recibió puñalada en el rostro, llegó a la sala de emergencia desorientado y hemiparético. Se comprobó la presencia de arma blanca intracraneal y luego de los exámenes de imagen se procedió en sala de operaciones a retirar el arma retenida, luego de hemostasia y cierre de fístula. Luego de la intervención quirúrgica, fue atendido en la Unidad de Cuidados Intensivos. El control tomográfico posoperatorio no evidenció sangrado. Hubo reversióncompleta de la hemiparesia, sin signos de fistula ni infección. El paciente tuvo una buena evolución hasta su egreso, 12 días más tarde. Discusión: Las imágenes tomográficas y de angiotomografía son de gran ayuda para el neurocirujano, quien precisa de esa información para prevenir potenciales complicaciones intraoperatorias y secuelas neurológicas en el tratamiento quirúrgico de pacientes que han sufrido un trauma craneoencefálico penetrante.


Introduction: Penetrating head injuries are becoming more and more frequent in nowadays socity, therefore, the neurosurgeon should be prepared to deal with. We must stick at rigid surgical protocols. Case: A young male patient stabbed on his face was admitted in the emergency unit of our hospital. He was disoriented and hemiparetic with a knife inside the skull shown by image examns. Patient was sent to the operating room where the neurosurgeon proceeded to remove the knife, under controlled conditions and hemostasis. A brain fistula was closed and the patient was sent to the Intensive Care Unit in the postoperative period. Tomographic control showed no bleeding. Eventually, he was discharged in good condition after 12 days with complete reversal of hemiparesis, without infection or fistula. Discusion: Tomographic imaging and angiography are useful tools for the neurosurgeon, who needs key information to prevent surgical complications and neurologic sequelae when dealing with patients who suffered penetrating head trauma.


Assuntos
Humanos , Masculino , Adulto , Paresia , Tomografia , Traumatismos Cranianos Penetrantes , Neurocirurgiões , Lesões Encefálicas Traumáticas , Hemostasia , Patologia , Emergências , Unidades de Terapia Intensiva
10.
Microb Drug Resist ; 21(1): 25-34, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25535825

RESUMO

The emergence of vancomycin intermediate Staphylococcus aureus (VISA) and heterogeneous VISA (hVISA) is of major concern worldwide. Our objective was to investigate the prevalence, phenotypic and molecular features of hVISA strains isolated from bacteremic patients and to determine the clinical significance of the hVISA phenotype in patients with bacteremia. A total of 104 S. aureus blood isolates were collected from a teaching hospital of Argentina between August 2009 and November 2010. No VISA isolate was recovered, and 3 out of 92 patients (3.3%) were infected with hVISA, 2 of them methicillin-resistant S. aureus (MRSA) (4.5% of MRSA). Macro Etest and prediffusion method detected 3/3 and 2/3 hVISA respectively. Considering the type of bacteremia, the three cases were distributed as follows: two patients had suffered multiple episodes of bacteremia (both hVISA strains recovered in the second episode), while only one patient had suffered a single episode of bacteremia with hVISA infection. MRSA bloodstream isolates exhibiting the hVISA phenotype were related to HA-MRSA Cordobes clone (ST5-SCCmec I-spa t149) and MRSA Argentinean pediatric clone (ST100-SCCmec IVNV-spa t002), but not to CA-MRSA-ST30-SCCmec IV-spa t019 clone that was one of the most frequent in our country. Although still relatively infrequent in our hospital, hVISA strains were significantly associated with multiple episodes of bacteremia (p=0.037) and genetically unrelated.


Assuntos
Bacteriemia/microbiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Resistência a Vancomicina , Área Sob a Curva , Argentina/epidemiologia , Bacteriemia/epidemiologia , Contagem de Colônia Microbiana , Farmacorresistência Bacteriana Múltipla , Genótipo , Hospitais de Ensino , Humanos , Estudos Prospectivos , Infecções Estafilocócicas/epidemiologia
12.
Artigo em Inglês | MEDLINE | ID: mdl-20957068

RESUMO

Rapid ischemic tolerance, induced one hour following ischemic preconditioning, is mediated via the ubiq-uitin-proteasome system and the degradation of the pro-apoptotic bcl-2 family protein Bim. Previous studies implicate adenosine A1 receptors in mediating rapid ischemic tolerance. Since the A1 adenosine receptor antagonist DPCPX (10µM) blocked rapid ischemic tolerance in our model, we investigated whether adenosine-mediated preconditioning induces rapid ischemic tolerance via the proteasomal degradation of Bim. Cultured rat cortical neurons were incubated for 60 minutes with either adenosine (1µM) or (-)-N(6)-(2-Phenyl-isopropyl) adenosine (RPIA (1µM)), prior to a harmful dose of ischemia (120min oxygen and glucose deprivation). Preconditioned cells had significantly lower levels of cell death following harmful ischemia when compared to non-preconditioned cells. The proteasome inhibitor MG132 (0.1µM) blocked the protective effect of adenosine pre-conditioning. Immunoblot analysis revealed a decrease in Bim protein levels in adenosine and RPIA preconditioned neurons. Adenosine preconditioning induced neuroprotection and Bim degradation was blocked by the MEK inhibitor UO126 (10µM). Our data suggests that pharmacological preconditioning with adenosine results in proteasomal Bim degradation mediated by p42/44 MAPK. Therefore, pharmacological approaches may be able to induce rapid ischemic tolerance via similar molecular mechanisms as ischemic preconditioning.

13.
Brain Res ; 1272: 71-80, 2009 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-19332039

RESUMO

Several recent studies suggest that sumo-2/3 modification of proteins occurs following harmful ischemia, however, sumo-2/3-ylation may also be associated with hibernation-mediated neuroprotection. Here we investigate the sumoylation of proteins following ischemia and ischemic tolerance using our established in vitro model of ischemia (oxygen and glucose deprivation; OGD). Following harmful ischemia (120 min OGD), we observed a significant increase in the sumo-2/3-ylation of high molecular weight proteins (>85 kDa), but not sumo-1-ylation of proteins. Sumo-2/3-ylation following 120 min OGD was reduced when cultures were preconditioned with non-harmful 30 min OGD 24 h earlier (delayed ischemic tolerance). However, we observed no change in sumo-2/3-ylation in a model of rapid ischemic tolerance. The effects of preconditioning on sumo-2/3-ylation following harmful ischemia were blocked by the protein synthesis inhibitor cycloheximide (1.0 muM), a known inhibitor of delayed ischemic tolerance. In addition, we observed a reduction in sumo-2/3-ylation using hypothermia (4 degrees C 30 min) as the preconditioning stimuli to induce delayed ischemic tolerance. Further studies show that sumo-2/3-ylation occurs during the ischemic insult and that preconditioning does not change expression of the sumo E1- and E2-ligases (UBA2 and Ubc9) or the sumo specific isopeptidases (SenP1-3). While sumo-2/3-ylation is enhanced under conditions of cell stress, it is not yet clear whether this is a cause or consequence of harmful ischemia-induced cell damage.


Assuntos
Regulação para Baixo/fisiologia , Neurônios/metabolismo , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Análise de Variância , Animais , Animais Recém-Nascidos , Células Cultivadas , Córtex Cerebral/citologia , Cicloeximida/farmacologia , Regulação para Baixo/efeitos dos fármacos , Glucose/deficiência , Hipertermia Induzida/métodos , Hipóxia/metabolismo , Precondicionamento Isquêmico/métodos , L-Lactato Desidrogenase/metabolismo , Neurônios/efeitos dos fármacos , Inibidores da Síntese de Proteínas/farmacologia , Ratos , Ratos Sprague-Dawley , Fatores de Tempo
14.
J Neurosci ; 28(1): 50-9, 2008 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-18171922

RESUMO

Ischemic tolerance is an endogenous neuroprotective mechanism in brain and other organs, whereby prior exposure to brief ischemia produces resilience to subsequent normally injurious ischemia. Although many molecular mechanisms mediate delayed (gene-mediated) ischemic tolerance, the mechanisms underlying rapid (protein synthesis-independent) ischemic tolerance are relatively unknown. Here we describe a novel mechanism for the induction of rapid ischemic tolerance mediated by the ubiquitin-proteasome system. Rapid ischemic tolerance is blocked by multiple proteasome inhibitors [carbobenzoxy-L-leucyl-L-leucyl-L-leucinal (MG132), MG115 (carbobenzoxy-L-leucyl-L-leucyl-L-norvalinal), and clasto-lactacystin-beta-lactone]. A proteomics strategy was used to identify ubiquitinated proteins after preconditioning ischemia. We focused our studies on two actin-binding proteins of the postsynaptic density that were ubiquitinated after rapid preconditioning: myristoylated, alanine-rich C-kinase substrate (MARCKS) and fascin. Immunoblots confirm the degradation of MARCKS and fascin after preconditioning ischemia. The loss of actin-binding proteins promoted actin reorganization in the postsynaptic density and transient retraction of dendritic spines. This rapid and reversible synaptic remodeling reduced NMDA-mediated electrophysiological responses and renders the cells refractory to NMDA receptor-mediated toxicity. The dendritic spine retraction and NMDA neuroprotection after preconditioning ischemia are blocked by actin stabilization with jasplakinolide, as well as proteasome inhibition with MG132. Together these data suggest that rapid tolerance results from changes to the postsynaptic density mediated by the ubiquitin-proteasome system, rendering neurons resistant to excitotoxicity.


Assuntos
Isquemia/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Sinapses/fisiologia , Ubiquitina/metabolismo , Análise de Variância , Animais , Animais Recém-Nascidos , Carbocianinas , Proteínas de Transporte/metabolismo , Morte Celular , Células Cultivadas , Córtex Cerebral/citologia , Inibidores Enzimáticos/farmacologia , Glucose/deficiência , Hipóxia/complicações , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Isquemia/etiologia , Precondicionamento Isquêmico , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Potenciais da Membrana/efeitos da radiação , Proteínas de Membrana/metabolismo , Proteínas dos Microfilamentos/metabolismo , Substrato Quinase C Rico em Alanina Miristoilada , Neurônios/citologia , Neurônios/efeitos dos fármacos , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-Dawley , Fatores de Tempo
15.
J Cereb Blood Flow Metab ; 28(2): 232-41, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17882162

RESUMO

As clinical trials of pharmacological neuroprotective strategies in stroke have been disappointing, attention has turned to the brain's own endogenous strategies for neuroprotection. Recently, a hypothesis has been offered that modified reperfusion subsequent to a prolonged ischemic episode may also confer ischemic neuroprotection, a phenomenon termed 'postconditioning'. Here we characterize both in vivo and in vitro models of postconditioning in the brain and offer data suggesting a biological mechanism for protection. Postconditioning treatment reduced infarct volume by up to 50% in vivo and by approximately 30% in vitro. A duration of 10 mins of postconditioning ischemia after 10 mins of reperfusion produced the most effective postconditioning condition both in vivo and in vitro. The degree of neuroprotection after postconditioning was equivalent to that observed in models of ischemic preconditioning. However, subjecting the brain to both preconditioning as well as postconditioning did not cause greater protection than each treatment alone. The prosurvival protein kinases extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAPK), and Akt show prolonged phosphorylation in the cortex of postconditioned rats. Neuroprotection after postconditioning was inhibited only in the presence of LY294002, which blocks Akt activation, but not U0126 or SB203580, which block ERK and P38 MAP kinase activity. In contrast, preconditioning-induced protection was blocked by LY294002, U0126, and SB203580. Our data suggest that postconditioning may represent a novel neuroprotective approach for focal ischemia/reperfusion, and one that is mediated, at least in part, by the activation of the protein kinase Akt.


Assuntos
Isquemia Encefálica/terapia , Acidente Vascular Cerebral/terapia , Animais , Isquemia Encefálica/complicações , Morte Celular , Circulação Cerebrovascular/fisiologia , Infarto da Artéria Cerebral Média/patologia , Masculino , Artéria Cerebral Média/fisiologia , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Quinases/metabolismo , Proteínas Quinases/fisiologia , Ratos , Ratos Sprague-Dawley , Reperfusão , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/fisiopatologia
16.
J Biol Chem ; 281(11): 7429-36, 2006 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-16431916

RESUMO

A previous exposure to a non-harmful ischemic insult (preconditioning) protects the brain against subsequent harmful ischemia (ischemic tolerance). In contrast to delayed gene-mediated ischemic tolerance, little is known about the molecular mechanisms that regulate rapid ischemic tolerance, which occurs within 1 h following preconditioning. Here we have investigated the degradation of the pro-apoptotic Bcl-2 family member Bim as a mechanism of rapid ischemic tolerance. Bim protein levels were reduced 1 h following preconditioning and occurred concurrent with an increase in Bim ubiquitination. Ubiquitinated proteins are degraded by the proteasome, and inhibition of the proteasome with MG132 (a proteasome inhibitor) prevented Bim degradation and blocked rapid ischemic tolerance. Inhibition of p42/p44 mitogen-activated protein kinase activation by U0126 reduced Bim ubiquitination and Bim degradation and blocked rapid ischemic tolerance. Finally, inhibition of Bim expression using antisense oligonucleotides also reduced cell death following ischemic challenge. Our results suggest that following preconditioning ischemia, Bim is rapidly degraded by the ubiquitin-proteasome system, resulting in rapid ischemic tolerance. This suggests that the rapid degradation of cell death-promoting proteins by the ubiquitin-proteasome pathway may represent a novel therapeutic strategy to reduce cell damage following neuropathological insults, e.g. stroke.


Assuntos
Proteínas Reguladoras de Apoptose/química , Proteínas de Membrana/química , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas Proto-Oncogênicas/química , Ubiquitina/química , Animais , Apoptose , Proteínas Reguladoras de Apoptose/metabolismo , Proteína 11 Semelhante a Bcl-2 , Butadienos/farmacologia , Morte Celular , Células Cultivadas , Inibidor de Quinase Dependente de Ciclina p21/química , Immunoblotting , Imuno-Histoquímica , Marcação In Situ das Extremidades Cortadas , Isquemia/patologia , Precondicionamento Isquêmico , Leupeptinas/química , Proteínas de Membrana/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Neurônios/metabolismo , Neurônios/patologia , Nitrilas/farmacologia , Oligonucleotídeos Antissenso/química , Fosforilação , Propídio/química , Proteínas Proto-Oncogênicas/metabolismo , Ratos , Ratos Sprague-Dawley , Fatores de Tempo
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