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1.
J Org Chem ; 89(9): 6230-6237, 2024 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-38629386

RESUMO

A concise synthesis of pareitropone by oxidative cyclization of a phenolic nitronate is delineated. The use of TMSOTf as an additive to promote the facile formation of a strained norcaradiene intermediate provides convenient access to highly condensed multicyclic tropones in high yields. This synthesis is modular, efficient, and scalable, highlighting the synthetic utility of radical anion coupling reactions in annulation reactions. This work is discussed in the context of total syntheses of the tropoloisoquinoline alkaloids. Also included are the preparation of several congeners and a brief description of their biological activities.


Assuntos
Antineoplásicos , Humanos , Estrutura Molecular , Ciclização , Linhagem Celular Tumoral , Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Antineoplásicos/química , Ensaios de Seleção de Medicamentos Antitumorais , Oxirredução
2.
J Korean Neurosurg Soc ; 66(4): 476-481, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36444420

RESUMO

OBJECTIVE: The latest version of the Leksell Gamma Knife IconTM allows for mask- and frame-based fixation. Although mask fixation provides fractionated treatment and immobilization using a noninvasive method, it is not free from collision. The authors investigated the collision problem with a modified mask fixation method. METHODS: This study presents a case of two meningiomas in the frontal area, where a collision occurs in the occipital area. A modified mask fixation method was introduced to avoid the collision : first, the edges of the head cushion were cut off and polystyrene beads with a diameter of approximately 5 cm were removed. Next, the head cushion was sealed using a stapler. Finally, the head cushion was flattened in the adapter. We compared the shot coordinates, 3-dimensional (3D) error, clearance distance, and vertical depth of the head cushion between the initial and modified mask fixations. RESULTS: When comparing the initial and modified mask fixations, the difference in the shot coordinates was +10.5 mm along the y-axis, the difference in the 3D error was approximately 18 mm, and the difference in clearance was -10.2 mm. The head cushion was approximately 8 mm deeper in the modified mask fixation. CONCLUSION: Based on these findings, we recommend a modified mask fixation method for gamma knife radiosurgery using ICON with a collision.

3.
Sci Rep ; 12(1): 4486, 2022 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-35296720

RESUMO

Augmented reality (AR) offers a new medical treatment approach. We aimed to evaluate frameless (mask) fixation navigation using a 3D-printed patient model with fixed-AR technology for gamma knife radiosurgery (GKRS). Fixed-AR navigation was developed using the inside-out method with visual inertial odometry algorithms, and the flexible Quick Response marker was created for object-feature recognition. Virtual 3D-patient models for AR-rendering were created via 3D-scanning utilizing TrueDepth and cone-beam computed tomography (CBCT) to generate a new GammaKnife Icon™ model. A 3D-printed patient model included fiducial markers, and virtual 3D-patient models were used to validate registration accuracy. Registration accuracy between initial frameless fixation and re-fixation navigated fixed-AR was validated through visualization and quantitative method. The quantitative method was validated through set-up errors, fiducial marker coordinates, and high-definition motion management (HDMM) values. A 3D-printed model and virtual models were correctly overlapped under frameless fixation. Virtual models from both 3D-scanning and CBCT were enough to tolerate the navigated frameless re-fixation. Although the CBCT virtual model consistently delivered more accurate results, 3D-scanning was sufficient. Frameless re-fixation accuracy navigated in virtual models had mean set-up errors within 1 mm and 1.5° in all axes. Mean fiducial marker differences from coordinates in virtual models were within 2.5 mm in all axes, and mean 3D errors were within 3 mm. Mean HDMM difference values in virtual models were within 1.5 mm of initial HDMM values. The variability from navigation fixed-AR is enough to consider repositioning frameless fixation without CBCT scanning for treating patients fractionated with large multiple metastases lesions (> 3 cm) who have difficulty enduring long beam-on time. This system could be applied to novel GKRS navigation for frameless fixation with reduced preparation time.


Assuntos
Realidade Aumentada , Radiocirurgia , Tomografia Computadorizada de Feixe Cônico/métodos , Marcadores Fiduciais , Humanos , Movimento (Física) , Radiocirurgia/métodos
4.
Neurosurg Focus ; 51(2): E21, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34333463

RESUMO

OBJECTIVE: With the advancement of 3D modeling techniques and visualization devices, augmented reality (AR)-based navigation (AR navigation) is being developed actively. The authors developed a pilot model of their newly developed inside-out tracking AR navigation system. METHODS: The inside-out AR navigation technique was developed based on the visual inertial odometry (VIO) algorithm. The Quick Response (QR) marker was created and used for the image feature-detection algorithm. Inside-out AR navigation works through the steps of visualization device recognition, marker recognition, AR implementation, and registration within the running environment. A virtual 3D patient model for AR rendering and a 3D-printed patient model for validating registration accuracy were created. Inside-out tracking was used for the registration. The registration accuracy was validated by using intuitive, visualization, and quantitative methods for identifying coordinates by matching errors. Fine-tuning and opacity-adjustment functions were developed. RESULTS: ARKit-based inside-out AR navigation was developed. The fiducial marker of the AR model and those of the 3D-printed patient model were correctly overlapped at all locations without errors. The tumor and anatomical structures of AR navigation and the tumors and structures placed in the intracranial space of the 3D-printed patient model precisely overlapped. The registration accuracy was quantified using coordinates, and the average moving errors of the x-axis and y-axis were 0.52 ± 0.35 and 0.05 ± 0.16 mm, respectively. The gradients from the x-axis and y-axis were 0.35° and 1.02°, respectively. Application of the fine-tuning and opacity-adjustment functions was proven by the videos. CONCLUSIONS: The authors developed a novel inside-out tracking-based AR navigation system and validated its registration accuracy. This technical system could be applied in the novel navigation system for patient-specific neurosurgery.


Assuntos
Realidade Aumentada , Cirurgia Assistida por Computador , Algoritmos , Humanos , Imageamento Tridimensional , Procedimentos Neurocirúrgicos
5.
ACS Appl Mater Interfaces ; 13(29): 33782-33789, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34258987

RESUMO

Interleukin-2 (IL-2) and its α receptor in soluble form (sIL-2Rα) are considered biomarkers for cancers and immune-related diseases. Enzyme-linked immunosorbent assay is the most common method used to evaluate biomarkers in clinical practice; it is precise but time-consuming and involves complicated procedures. Here, we have developed a rapid yet accurate modality for cancer diagnosis that enables on-site evaluation of cancer markers, that is, IL-2 and sIL-2Rα, without complicated pretreatment of cancer patient-derived blood samples. Surface plasmon resonance and bioresponsive microgels conjugated with IL-2 receptors, that is, IL-2Rß and IL-2Rγ, were utilized to measure IL-2 and sIL-2Rα levels via multivalent protein binding (MPB) between the ligands and their receptors. Our results showed that this novel method enables us to perform cancer diagnosis with a 1000-fold dilution of serum in 10 min. The advantage of MPB-based cancer diagnosis originates from its great selectivity for a target molecule and tolerance to a myriad of nonspecific substances in serum, which allows on-site clinical evaluation. Importantly, our finding implies that MPB-based cancer diagnosis provides a new paradigm not only for improving cancer treatment but also for evaluating a target molecule in unpurified and complex solutions such as blood.


Assuntos
Biomarcadores Tumorais/sangue , Subunidade alfa de Receptor de Interleucina-2/sangue , Interleucina-2/sangue , Microgéis/química , Neoplasias/diagnóstico , Resinas Acrílicas/síntese química , Resinas Acrílicas/química , Humanos , Proteínas Imobilizadas/química , Subunidade alfa de Receptor de Interleucina-2/química , Neoplasias/sangue , Ressonância de Plasmônio de Superfície/métodos
6.
Sci Rep ; 11(1): 7005, 2021 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-33772092

RESUMO

The usefulness of 3-dimensional (3D)-printed disease models has been recognized in various medical fields. This study aims to introduce a production platform for patient-specific 3D-printed brain tumor model in clinical practice and evaluate its effectiveness. A full-cycle platform was created for the clinical application of a 3D-printed brain tumor model (3D-printed model) production system. Essential elements included automated segmentation software, cloud-based interactive communication tools, customized brain models with exquisite expression of brain anatomy in transparent material, adjunctive devices for surgical simulation, and swift process cycles to meet practical needs. A simulated clinical usefulness validation was conducted in which neurosurgeons assessed the usefulness of the 3D-printed models in 10 cases. We successfully produced clinically applicable patient-specific models within 4 days using the established platform. The simulated clinical usefulness validation results revealed the significant superiority of the 3D-printed models in surgical planning regarding surgical posture (p = 0.0147) and craniotomy design (p = 0.0072) compared to conventional magnetic resonance images. The benefit was more noticeable for neurosurgeons with less experience. We established a 3D-printed brain tumor model production system that is ready to use in daily clinical practice for neurosurgery.


Assuntos
Neoplasias Encefálicas/patologia , Simulação por Computador , Imageamento por Ressonância Magnética/métodos , Neurocirurgiões/estatística & dados numéricos , Neurocirurgia/métodos , Impressão Tridimensional/estatística & dados numéricos , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/cirurgia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Anatômicos , Prognóstico , Estudos Retrospectivos , Adulto Jovem
7.
ACS Appl Mater Interfaces ; 12(5): 5413-5419, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31898885

RESUMO

Precise identification of protein-protein interactions is required to improve our understanding of biochemical pathways for biology and medicine. In physiology, how proteins interact with other proteins or small molecules is crucial for maintaining biological functions. For instance, multivalent protein binding (MPB), in which a ligand concurrently interacts with two or more receptors, plays a key role in regulating complex but accurate biological functions, and its interference is related to many diseases. Therefore, determining MPB and its kinetics has long been sought, which currently requires complicated procedures and instruments to distinguish multivalent binding from monovalent binding. Here, we show a method for quickly evaluating the MPB over monovalent binding and its kinetic parameters in a label-free manner. Engaging pNIPAm-co-AAc nanogels with MPB-capable moieties (e.g., PD-1 antigen and biocytin) permits a surface plasmon resonance (SPR) instrument to evaluate the MPB events by amplifying signals from the specific target molecules. Using our MPB-based method, PD-1 antibody that forms a type of MPB by complexing with two PD-1 proteins, which are currently used for cancer immunotherapy, is detectable down to a level of 10 nM. In addition, small multivalent cations (e.g., Ca2+, Fe2+, and Fe3+) are distinguishably measurable over monovalent cations (e.g., Na+ and K+) with the pNIPAm-co-AAc nanogels.


Assuntos
Técnicas Biossensoriais/métodos , Lisina/análogos & derivados , Nanogéis/química , Receptor de Morte Celular Programada 1/metabolismo , Ressonância de Plasmônio de Superfície , Acrilamidas/química , Anticorpos/imunologia , Cálcio/química , Ferro/química , Cinética , Ligantes , Lisina/química , Lisina/metabolismo , Receptor de Morte Celular Programada 1/química , Receptor de Morte Celular Programada 1/imunologia , Ligação Proteica , Razão Sinal-Ruído
8.
Int J Med Sci ; 16(11): 1453-1460, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31673236

RESUMO

Colorectal cancer (CRC) is one of the most frequently lethal forms of cancer. Intramucosal injection allows development of better mouse models of CRC, as orthotopic xenografts allow development of adenocarcinoma in the submucosa of the mouse colon wall. In this paper, a method of orthotopic injection is monitored longitudinally using cellular-resolution real-time in vivo fluorescence microendoscopy, following the injection of three different cell lines: 3T3-GFP to confirm immunosuppression and HCT116-RFP cells to model CRC. Adenoma formation is first observable after 7 to 10 days, and by use of 33 G needles a tumor induction rate of greater than 85% is documented. An additional experiment on the injection of rapamycin reveals drug efficacy and localization between 24 and 48 hours, and suggests the promise of real-time cellular-resolution fluorescence micro-endoscopy for developing longitudinal therapy regimes in mural models of CRC.


Assuntos
Adenocarcinoma/patologia , Adenoma/patologia , Neoplasias Colorretais/patologia , Xenoenxertos/patologia , Animais , Colo/patologia , Modelos Animais de Doenças , Células HCT116 , Humanos , Camundongos
9.
Childs Nerv Syst ; 31(6): 985-9, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25771921

RESUMO

INTRODUCTION: A pituicytoma in the sellar area is extremely rare in children and, due to its highly vascularized nature, can be difficult to address using the transsphenoid approach (TSA) to surgery. Here, we report a rare case of a pituicytoma that was completely removed from a child through a staged operation using the TSA. A 13-year-old girl was admitted with a 1-year history of visual disturbance and amenorrhea. Visual field examination showed left total blindness and right temporal hemianopsia. Laboratory results revealed hormonal levels all within normal ranges. Brain magnetic resonance imaging (MRI) showed a homogeneous, highly enhancing sellar and suprasellar mass, typically suggestive of a pituitary adenoma. TSA surgery revealed the tumor had a rubbery-firm consistency, hypervascularity, and profuse bleeding. We removed the tumor partially and planned a second-stage operation. DISCUSSION: Gross total removal is the treatment of choice for this type of tumor. Attempted resection of these presumed adenomas or meningiomas using the TSA often results in unexpectedly heavy intraoperative bleeding due to the high vascularity of this rare tumor, making surgery challenging, especially in children where the tumor is within a relatively narrow corridor. While pituicytomas are a rare differential diagnosis for sellar or parasellar tumors in children, total removal by second-stage TSA surgery is indicated in the case of profuse bleeding or uncertainty of biopsy. Following first-stage TSA surgery and pathologic confirmation of pituicytoma, the strategy is typically gross total removal during second-stage TSA surgery. CONCLUSIONS: Although very rare in children, a pituicytoma should be included in the differential diagnosis of a mass in the sellar area if the tumor is highly enhancing or very vascular. Second-stage TSA surgery is another strategy when the pathology is not clear during the first-stage TSA surgery.


Assuntos
Glioma/cirurgia , Hipófise/cirurgia , Neoplasias Hipofisárias/cirurgia , Seio Esfenoidal/cirurgia , Adolescente , Feminino , Humanos , Imageamento por Ressonância Magnética
10.
J Korean Neurosurg Soc ; 54(3): 261-4, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24278661

RESUMO

We report a long-term survival case of a primary malignant intracerebral nerve sheath tumor (MINST) occurring in the right frontal lobe of a 13-year old boy. After the gross total resection (GTR), we have performed radiation therapy but it recurred 50 months after the surgery, so the second GTR was performed. Later, second tumor recurrence was found 4 months after the second surgery. Subsequently the third GTR, radiotherapy, and chemotherapy were carried out. At present, the patient has been remaining alive for 77 months without evidence of tumor recurrence. According to the previous reports, the primary MINST is very rare : there are only 8 cases reported. It is also a fast-growing, invasive tumor with poor outcome. This is the first case that had no recurrence for 50 months after the surgery among the reported cases that had been followed up for more than 5 years. It is supposed that a period of recurrence free survival after GTR and low mitotic activity are associated with the patient's prognosis. A GTR followed by adjuvant radiation therapy and chemotherapy will be recommended to patients of MINST.

11.
J Korean Neurosurg Soc ; 52(3): 234-9, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23115667

RESUMO

OBJECTIVE: Chronic subdural hematoma (CSDH) is a typical disease that is encountered frequently in neurosurgical practice. The medications which could cause coagulopathies were known as one of the risk factors of CSDH, such as anticoagulants (ACs) and antiplatelet agents (APs). Recently, the number of patients who are treated with ACs/APs is increasing, especially in the elderly population. With widespread use of these drugs, there is a need to study the changes in risk factors of CSDH patients. METHODS: We retrospectively reviewed 290 CSDH patients who underwent surgery at our institute between 1996 and 2010. We classified them into three groups according to the time of presentation (Group A : the remote period group, 1996-2000, Group B : the past period group, 2001-2005, and Group C : the recent period group, 2006-2010). Also, we performed the comparative analysis of independent risk factors between three groups. RESULTS: Among the 290 patients, Group A included 71 patients (24.5%), Group B included 98 patients (33.8%) and Group C included 121 patients (41.7%). Three patients (4.2%) in Group A had a history of receiving ACs/APs, 8 patients (8.2%) in Group B, and 19 patients (15.7%) in Group C. Other factors such as head trauma, alcoholism, epilepsy, previous neurosurgery and underlying disease having bleeding tendency were also evaluated. In ACs/APs related cause of CSDH in Group C, significantly less proportion of the patients are associated with trauma or alcohol compared to the non-medication group. CONCLUSION: In this study, the authors concluded that ACs/APs have more importance as a risk factor of CSDH in the recent period compared to the past. Therefore, doctors should prescribe these medications carefully balancing the potential risk and benefit.

12.
Mol Med Rep ; 6(1): 88-92, 2012 07.
Artigo em Inglês | MEDLINE | ID: mdl-22505191

RESUMO

Currently, clinically available options for treating glioblastoma (GBM) are quite limited, and there is a clear need to develop novel treatment strategies that can more effectively manage tumors. Here, we present a combination treatment of temozolomide (TMZ), a blood-brain barrier penetrating DNA alkylating agent, and ZD6474 (vandetanib), a VEGFR2 and EGFR dual-targeting anti-angiogenic agent, as a novel treatment strategy for GBM. In a U-87MG orthotopic xenograft model, the combination treatment provided a marked 94% tumor volume reduction. This reduction was greater than that achieved by monotherapy of either agent, and was correlated with a statistically significant reduction in microvessel density (CD31+ cells) and proliferation (PCNA+ cells). These results confirm the necessity to target angiogenesis in addition to utilizing cytotoxic approaches, and provide the rationale for application of TMZ + ZD6474 combination therapy for treating GBM patients in the clinical setting.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Glioblastoma/tratamento farmacológico , Inibidores da Angiogênese/administração & dosagem , Animais , Antineoplásicos/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Linhagem Celular Tumoral , Proliferação de Células , Dacarbazina/administração & dosagem , Dacarbazina/análogos & derivados , Sinergismo Farmacológico , Glioblastoma/patologia , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Microvasos/efeitos dos fármacos , Piperidinas/administração & dosagem , Quinazolinas/administração & dosagem , Temozolomida , Carga Tumoral/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto
13.
J Korean Neurosurg Soc ; 50(3): 256-9, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22102960

RESUMO

We report a rare case of Williams syndrome accompanying moyamoya disease in whom postoperative global cerebral infarction occurred unpredictably. Williams syndrome is an uncommon hereditary disorder associated with the connective tissue abnormalities and cardiovascular disease. To our knowledge, our case report is the second case of Williams syndrome accompanying moyamoya disease. A 9-year-old boy was presented with right hemiparesis after second operation for coarctation of aorta. He was diagnosed as having Williams syndrome at the age of 1 year. Brain MRI showed left cerebral cortical infarction, and angiography showed severe stenosis of bilateral internal carotid arteries and moyamoya vessels. To reduce the risk of furthermore cerebral infarction, we performed indirect anastomosis successfully. Postoperatively, the patient recovered well, but at postoperative third day, without any unusual predictive abnormal findings the patient's pupils were suddenly dilated. Brain CT showed the global cerebral infarction. Despite of vigorous treatment, the patient was not recovered and fell in brain death one week later. We suggest that in this kind of labile patient with Williams syndrome accompanying moyamoya disease, postoperative sedation should be done with more thorough strict patient monitoring than usual moyamoya patients. Also, we should decide the revascularization surgery more cautiously than usual moyamoya disease. The possibility of unpredictable postoperative ischemic complication should be kept in mind.

14.
Physiol Genomics ; 30(1): 1-7, 2007 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-17327491

RESUMO

Regression of cardiac hypertrophy and improvement of the functional capacity of failing hearts have reportedly been achieved by mechanical unloading in cardiac work. In this study, cardiac hypertrophy was first induced in rats by transverse aortic constriction and then mechanically unloaded by relieving the constriction after significant cardiac hypertrophy had developed. Hypertrophy was significantly regressed at the cellular and molecular levels at day 1, 3, and 7 after constriction relief. Gene profiling analysis revealed that 52 genes out of 9,911 genes probed on a gene array were specifically upregulated during the early regression period. Among these regression-induced genes, Eyes absent 2 (eya2) was of particular interest because it is a transcriptional cofactor involved in mammalian organogenesis as well as Drosophila eye development. Adenovirus-mediated overexpression of eya2 in rat neonatal cardiomyocytes completely abrogated phenylephrine-induced development of cardiomyocyte hypertrophy as determined by cell size, sarcomere rearrangement and fetal gene re-expression. Our data strongly suggest that transcriptional programs distinct from those mediating cardiac hypertrophy may be operating during the regression of hypertrophy, and eya2 may be a key regulator of one of these programs.


Assuntos
Cardiomegalia/genética , Perfilação da Expressão Gênica/métodos , Miócitos Cardíacos/metabolismo , Animais , Animais Recém-Nascidos , Western Blotting , Cardiomegalia/metabolismo , Cardiomegalia/fisiopatologia , Linhagem Celular , Células Cultivadas , Análise por Conglomerados , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Miócitos Cardíacos/citologia , Miócitos Cardíacos/efeitos dos fármacos , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos/métodos , Fenilefrina/farmacologia , Pressão , Ratos , Ratos Sprague-Dawley , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos
15.
J Biol Chem ; 281(47): 35954-64, 2006 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-16954223

RESUMO

Neuritogenesis requires active actin cytoskeleton rearrangement in which Rho GTPases play a pivotal role. In a previous study (Shin, E. Y., Woo, K. N., Lee, C. S., Koo, S. H., Kim, Y. G., Kim, W. J., Bae, C. D., Chang, S. I., and Kim, E. G. (2004) J. Biol. Chem. 279, 1994-2004), we demonstrated that betaPak-interacting exchange factor (betaPIX) guanine nucleotide exchange factor (GEF) mediates basic fibroblast growth factor (bFGF)-stimulated Rac1 activation through phosphorylation of Ser-525 and Thr-526 at the GIT-binding domain (GBD). However, the mechanism by which this phosphorylation event regulates the Rac1-GEF activity remained elusive. We show here that betaPIX binds to Rac1 via the GBD and also activates the GTPase via an associated GEF, smgGDS, in a phosphorylation-dependent manner. Notably, the Rac1-GEF activity of betaPIX persisted for an extended period of time following bFGF stimulation, unlike other Rho GEFs containing the Dbl homology domain. We demonstrate that C-PIX, containing proline-rich, GBD, and leucine zipper domains can interact with Rac1 via the GBD in vitro and in vivo and also mediated bFGF-stimulated Rac1 activation, as determined by a modified GEF assay and fluorescence resonance energy transfer analysis. However, nonphosphorylatable C-PIX (S525A/T526A) failed to generate Rac1-GTP. Finally, betaPIX is shown to form a trimeric complex with smgGDS and Rac1; down-regulation of smgGDS expression by short interfering RNA causing significant inhibition of betaPIX-mediated Rac1 activation and neurite outgrowth. These results provide evidence for a new and unexpected mechanism whereby betaPIX can regulate Rac1 activity.


Assuntos
Proteínas de Ciclo Celular/fisiologia , Fator 2 de Crescimento de Fibroblastos/química , Fatores de Troca do Nucleotídeo Guanina/química , Neuritos/metabolismo , Proteínas Serina-Treonina Quinases/fisiologia , Proteínas rac1 de Ligação ao GTP/metabolismo , Animais , Proteínas de Ciclo Celular/química , Proliferação de Células , Ativação Enzimática , Proteínas de Fluorescência Verde/química , Fatores de Troca do Nucleotídeo Guanina/fisiologia , Humanos , Modelos Biológicos , Células PC12 , Proteínas Serina-Treonina Quinases/química , Ratos , Proteínas Recombinantes/química , Fatores de Troca de Nucleotídeo Guanina Rho , Quinases Ativadas por p21
16.
Artigo em Inglês | MEDLINE | ID: mdl-16484076

RESUMO

Groundwater samples contaminated by BTEX (benzene, toluene, ethylbenzene, xylene isomers and TPHs (total petroleum hydrocarbons) were treated with advanced oxidation processes (AOPs), such as TiO(2) photocatalysis and Fe(2+)/H(2)O(2) exposed to solar light (37 degrees N and 128 degrees E) with an average intensity of 1.7 mW/cm(2) at 365 nm. These AOP processes showed feasibility in the treatment of groundwater contaminated with BTEX, TPH and TOC (Total Organic Carbon). Outdoor field tests showed that the degradation efficiency of each contaminant was higher in the Fe(2+)/H(2)O(2) system without solar light compared to the TiO(2)/solar light and H(2)O(2)/solar light systems. However, the TiO(2)/solar light and the Fe(2+)/H(2)O(2)/solar light systems showed significantly enhanced efficiencies in the degradation of BTEX, TPH and TOC with the additional use of H(2)O(2). Near complete degradation of BTEX and TPH was observed within 2 and 4 hrs, respectively, however, that of TOC was slower. Without pretreatment of the groundwater, fouling of the TiO(2), due to the ionic species present, was observed within 1 hr of operation, which resulted in the inhibition of further BTEX, TPH and TOC destruction. The degradation rate of n-alkanes with carbon numbers ranging from C10 to C15 was relatively greater than that of n-alknaes with carbon numbers ranging from C16 to C20. From this work, the AOP process (Fe(2+)/H(2)O(2)/solar light and TiO(2)/H(2)O(2)/solar light) illuminated with solar light was identified as an effective ex situ technique in the remediation of groundwater contaminated with petroleum.


Assuntos
Compostos Ferrosos/química , Hidrocarbonetos/metabolismo , Petróleo/metabolismo , Sistema Solar , Titânio/química , Poluentes Químicos da Água/metabolismo , Carbono/metabolismo , Catálise , Cromatografia Gasosa , Peróxido de Hidrogênio/química , Cinética , Fotoquímica , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos
17.
Environ Sci Technol ; 39(7): 2101-6, 2005 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-15871243

RESUMO

The direct ultraviolet (UV) photolysis of N-nitrosodimethyl-amine (NDMA), a well-known potential carcinogen, was investigated in aqueous solution with its degradation products analyzed quantitatively. NDMA is known to be photolyzed either to dimethylamine (DMA) or to methylamine (MA) by two distinct pathways. However, the mechanism through which NDMA is photolyzed to DMA is still not clearly understood. This study reveals a new mechanistic pathway of NDMA photolysis to DMA by identifying the factors influencing the photolysis pathway. The two pathways of NDMA photolysis were found to be strongly dependent on the initial NDMA concentration and solution pH. Increasing the initial NDMA concentration clearly favored the DMA formation path. DMA production was optimized in the region of pH 4-5. The nitrite ion (NO2-) produced from the NDMA photolysis was identified as a key reagent in directing the NDMA photolysis toward DMA production. The observed photolytic behaviors of NDMA photolysis could be successfully explained in terms of the new mechanism involving the role of NO2-.


Assuntos
Dimetilnitrosamina/química , Fotólise/efeitos da radiação , Raios Ultravioleta , Água/química , Cromatografia Líquida de Alta Pressão , Dimetilaminas/química , Concentração de Íons de Hidrogênio , Metilaminas/química , Modelos Químicos
18.
J Biol Chem ; 277(46): 44417-30, 2002 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-12226077

RESUMO

Guanine nucleotide exchange factors (GEFs) have been implicated in growth factor-induced neuronal differentiation through the activation of small GTPases. Although phosphorylation of these GEFs is considered an activation mechanism, little is known about the upstream of PAK-interacting exchange factor (PIX), a member of the Dbl family of GEFs. We report here that phosphorylation of p85 betaPIX/Cool/p85SPR is mediated via the Ras/ERK/PAK2 pathway. To understand the role of p85 betaPIX in basic fibroblast growth factor (bFGF)-induced neurite outgrowth, we established PC12 cell lines that overexpress the fibroblast growth factor receptor-1 in a tetracycline-inducible manner. Treatment with bFGF induces the phosphorylation of p85 betaPIX, as determined by metabolic labeling and mobility shift upon gel electrophoresis. Interestingly, phosphorylation of p85 betaPIX is inhibited by PD98059, a specific MEK inhibitor, suggesting the involvement of the ERK cascade. PAK2, a major PAK isoform in PC12 cells as well as a binding partner of p85 betaPIX, also functions upstream of p85 betaPIX phosphorylation. Surprisingly, PAK2 directly binds to ERK, and its activation is dependent on ERK. p85 betaPIX specifically localizes to the lamellipodia at neuronal growth cones in response to bFGF. A mutant form of p85 betaPIX (S525A/T526A), in which the major phosphorylation sites are replaced by alanine, shows significant defect in targeting. Moreover, expression of the mutant p85 betaPIX efficiently blocks PC12 cell neurite outgrowth. Our study defines a novel signaling pathway for bFGF-induced neurite outgrowth that involves activation of the PAK2-p85 betaPIX complex via the ERK cascade and subsequent translocation of this complex.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Fator 2 de Crescimento de Fibroblastos/metabolismo , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Neurônios/fisiologia , Transdução de Sinais , Animais , Diferenciação Celular , Divisão Celular , Células Cultivadas , Ativação Enzimática , Immunoblotting , Microscopia de Fluorescência , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Modelos Biológicos , Neurônios/citologia , Células PC12 , Fosforilação , Plasmídeos/metabolismo , Testes de Precipitina , Ligação Proteica , Isoformas de Proteínas , Transporte Proteico , Ratos , Fatores de Troca de Nucleotídeo Guanina Rho , Serina/metabolismo , Tetraciclina/farmacologia , Treonina/metabolismo , Fatores de Tempo , Transfecção
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