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1.
Epilepsy Behav ; 139: 109072, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36652897

RESUMO

Neuronal synchronization is important for communication between brain regions and plays a key role in learning. However, changes in connectivity can lead to hyper-synchronized states related to epileptic seizures that occur intermittently with asynchronous states. The activity-regulated cytoskeleton-associated protein (ARC) is related to synaptic alterations which can lead to epilepsy. Induction of status epilepticus in rodent models causes the appearance of intense ARC immunoreactive neurons (IAINs), which present a higher number of connections and conductance intensity than non-IAINs. This alteration might contribute to abnormal epileptic seizure activity. In this work, we investigated how IAINs connectivity influences the firing pattern and synchronization in neural networks. Firstly, we showed the appearance of synchronized burst patterns due to the emergence of IAINs. Second, we described how the increase of IAINs connectivity favors the appearance of intermittent up and down activities associated with synchronous bursts and asynchronous spikes, respectively. Once the intermittent activity was properly characterized, we applied the optogenetics control of the high synchronous activities in the intermittent regime. To do this, we considered that 1% of neurons were transfected and became photosensitive. We observed that optogenetics methods to control synchronized burst patterns are effective when IAINs are chosen as photosensitive, but not effective in non-IAINs. Therefore, our analyses suggest that IAINs play a pivotal role in both the generation and suppression of highly synchronized activities.


Assuntos
Epilepsia do Lobo Temporal , Epilepsia , Estado Epiléptico , Humanos , Convulsões , Estado Epiléptico/metabolismo , Neurônios/metabolismo
2.
Semin Cell Dev Biol ; 95: 54-73, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-29782926

RESUMO

Oligodendrocytes are fundamental for the functioning of the nervous system; they participate in several cellular processes, including axonal myelination and metabolic maintenance for astrocytes and neurons. In the mammalian nervous system, they are produced through waves of proliferation and differentiation, which occur during embryogenesis. However, oligodendrocytes and their precursors continue to be generated during adulthood from specific niches of stem cells that were not recruited during development. Deficiencies in the formation and maturation of these cells can generate pathologies mainly related to myelination. Understanding the mechanisms involved in oligodendrocyte development, from the precursor to mature cell level, will allow inferring therapies and treatments for associated pathologies and disorders. Such mechanisms include cell signalling pathways that involve many growth factors, small metabolic molecules, non-coding RNAs, and transcription factors, as well as specific elements of the extracellular matrix, which act in a coordinated temporal and spatial manner according to a given stimulus. Deciphering those aspects will allow researchers to replicate them in vitro in a controlled environment and thus mimic oligodendrocyte maturation to understand the role of oligodendrocytes in myelination in pathologies and normal conditions. In this study, we review these aspects, based on the most recent in vivo and in vitro data on oligodendrocyte generation and differentiation.


Assuntos
Diferenciação Celular , Oligodendroglia/citologia , Oligodendroglia/metabolismo , Transdução de Sinais , Animais , Matriz Extracelular/metabolismo , Humanos , Bainha de Mielina/metabolismo , Células-Tronco Neurais/citologia , Células-Tronco Neurais/metabolismo
3.
Clin Oncol (R Coll Radiol) ; 34(10): e430-e436, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35715341

RESUMO

AIMS: A novel bladder preservation therapy, the OMC (Osaka Medical College) regimen, which combines radiation therapy with balloon-occluded arterial infusion of anticancer agents, is a treatment option for patients with muscle-invasive bladder cancer (MIBC). We retrospectively analysed the effects of changes in radiation dose and irradiation field on treatment efficacy and adverse events.The purpose of this study is to use the results of this study to help determine a course of radiation therapy for bladder preservation therapy of cT2N0M0 MIBC. MATERIALS AND METHODS: We examined 352 patients with clinical stage T2N0M0 (cT2N0M0) MIBC classified into the following groups based on the irradiation method: group A, the whole pelvis (50 Gy/25 fractions) + local bladder (10 Gy/5 fractions); group B, the small pelvis (50 Gy/25 fractions) + local bladder (10 Gy/5 fractions); group C, the whole pelvis (40 Gy/20 fractions) + local bladder (10 Gy/5 fractions). RESULTS: The complete response rate, 3-year overall survival and progression-free survival rates in group A were 92.9%, 94.9% and 82.1%, respectively; in group B were 87.2%, 86.7% and 76.7%, respectively; and in group C were 95.2%, 92.6% and 71.1%, respectively. No significant differences between the groups were noted. The incidence of ≥grade 3 urinary tract and gastrointestinal toxicities were not significantly different among the groups (group A: 7.8%, 1.7%; B, 11.1%, 0%; C, 7.1%, 1.8%, respectively). The 3-year progression-free rates of the common iliac lymph node (CILN) region in patients who received whole-pelvis and small-pelvis irradiation were 99.0 and 89.0% (P < 0.01), respectively, with the latter group having significantly high lymph node recurrence in the CILN region. CONCLUSIONS: Our findings showed that the optimal radiation therapy for patients with cT2N0M0 MIBC undergoing the OMC regimen is whole-pelvis irradiation including the CILN region, with a total dose of 50 Gy/25 fractions.


Assuntos
Antineoplásicos , Oclusão com Balão , Neoplasias da Bexiga Urinária , Antineoplásicos/uso terapêutico , Cisplatino , Terapia Combinada , Desoxicitidina , Intervalo Livre de Doença , Humanos , Estudos Retrospectivos , Bexiga Urinária , Neoplasias da Bexiga Urinária/patologia
4.
Biochim Biophys Acta ; 1803(2): 246-60, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19958796

RESUMO

Spontaneous Ca(2+) events have been observed in diverse stem cell lines, including carcinoma and mesenchymal stem cells. Interestingly, during cell cycle progression, cells exhibit Ca(2+) transients during the G(1) to S transition, suggesting that these oscillations may play a role in cell cycle progression. We aimed to study the influence of promoting and blocking calcium oscillations in cell proliferation and cell cycle progression, both in neural progenitor and undifferentiated cells. We also identified which calcium stores are required for maintaining these oscillations. Both in neural progenitor and undifferentiated cells calcium oscillations were restricted to the G1/S transition, suggesting a role for these events in progression of the cell cycle. Maintenance of the oscillations required calcium influx only through inositol 1,4,5-triphosphate receptors (IP(3)Rs) and L-type channels in undifferentiated cells, while neural progenitor cells also utilized ryanodine-sensitive stores. Interestingly, promoting calcium oscillations through IP(3)R agonists increased both proliferation and levels of cell cycle regulators such as cyclins A and E. Conversely, blocking calcium events with IP(3)R antagonists had the opposite effect in both undifferentiated and neural progenitor cells. This suggests that calcium events created by IP(3)Rs may be involved in cell cycle progression and proliferation, possibly due to regulation of cyclin levels, both in undifferentiated cells and in neural progenitor cells.


Assuntos
Células-Tronco Adultas/fisiologia , Sinalização do Cálcio/fisiologia , Cálcio/metabolismo , Carcinoma Embrionário/metabolismo , Ciclo Celular/fisiologia , Diferenciação Celular/fisiologia , Células-Tronco Adultas/citologia , Animais , Carcinoma Embrionário/patologia , Proliferação de Células , Quinases Ciclina-Dependentes/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Neurônios/citologia , Neurônios/fisiologia
5.
J Cell Biol ; 152(3): 519-30, 2001 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-11157979

RESUMO

Vps30p/Apg6p is required for both autophagy and sorting of carboxypeptidase Y (CPY). Although Vps30p is known to interact with Apg14p, its precise role remains unclear. We found that two proteins copurify with Vps30p. They were identified by mass spectrometry to be Vps38p and Vps34p, a phosphatidylinositol (PtdIns) 3-kinase. Vps34p, Vps38p, Apg14p, and Vps15p, an activator of Vps34p, were coimmunoprecipitated with Vps30p. These results indicate that Vps30p functions as a subunit of a Vps34 PtdIns 3-kinase complex(es). Phenotypic analyses indicated that Apg14p and Vps38p are each required for autophagy and CPY sorting, respectively, whereas Vps30p, Vps34p, and Vps15p are required for both processes. Coimmunoprecipitation using anti-Apg14p and anti-Vps38p antibodies and pull-down experiments showed that two distinct Vps34 PtdIns 3-kinase complexes exist: one, containing Vps15p, Vps30p, and Apg14p, functions in autophagy and the other containing Vps15p, Vps30p, and Vps38p functions in CPY sorting. The vps34 and vps15 mutants displayed additional phenotypes such as defects in transport of proteinase A and proteinase B, implying the existence of another PtdIns 3-kinase complex(es). We propose that multiple Vps34p-Vps15p complexes associated with specific regulatory proteins might fulfill their membrane trafficking events at different sites.


Assuntos
Autofagia , Carboxipeptidases/metabolismo , Proteínas Fúngicas/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Transporte Proteico/fisiologia , Saccharomyces cerevisiae/enzimologia , Catepsina A , Fracionamento Celular , Complexos Endossomais de Distribuição Requeridos para Transporte , Immunoblotting , Substâncias Macromoleculares , Modelos Biológicos , Mutação , Fenótipo , Plasmídeos , Testes de Precipitina , Proteínas Recombinantes de Fusão/metabolismo , Saccharomyces cerevisiae/fisiologia , Proteínas de Saccharomyces cerevisiae , Proteína VPS15 de Distribuição Vacuolar
6.
Science ; 286(5445): 1722-4, 1999 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-10576736

RESUMO

F0F1, found in mitochondria or bacterial membranes, synthesizes adenosine 5'-triphosphate (ATP) coupling with an electrochemical proton gradient and also reversibly hydrolyzes ATP to form the gradient. An actin filament connected to a c subunit oligomer of F0 was able to rotate by using the energy of ATP hydrolysis. The rotary torque produced by the c subunit oligomer reached about 40 piconewton-nanometers, which is similar to that generated by the gamma subunit in the F1 motor. These results suggest that the gamma and c subunits rotate together during ATP hydrolysis and synthesis. Thus, coupled rotation may be essential for energy coupling between proton transport through F0 and ATP hydrolysis or synthesis in F1.


Assuntos
Trifosfato de Adenosina/metabolismo , Proteínas Motores Moleculares/química , Proteínas Motores Moleculares/metabolismo , ATPases Translocadoras de Prótons/química , ATPases Translocadoras de Prótons/metabolismo , Actinas/química , Actinas/metabolismo , Sítios de Ligação , Biotinilação , Transferência de Energia , Enzimas Imobilizadas , Escherichia coli/enzimologia , Hidrólise , Força Próton-Motriz , Desacopladores/metabolismo , Desacopladores/farmacologia , Venturicidinas/farmacologia , Gravação em Vídeo
7.
Neuroscience ; 151(4): 995-1005, 2008 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-18248909

RESUMO

Synaptic modulation by activity-dependent changes constitutes a cellular mechanism for neuronal plasticity. However, it is not clear how the complete lack of neuronal signaling specifically affects elements involved in the communication between neurons. In the retina, it is now well established that both chemical and electrical synapses are essential to mediate the transmission of visual signaling triggered by the photoreceptors. In this study, we compared the expression of synaptic proteins in the retinas of wild-type (WT) vs. rd/rd mice, an animal model that displays inherited and specific ablation of photoreceptors caused by a mutation in the gene encoding the beta-subunit of rod cGMP-phosphodiesterase (Pde6brd1). We specifically examined the expression of connexins (Cx), the proteins that form the gap junction channels of electrical synapses, in addition to synaptophysin and synapsin I, which are involved in the release of neurotransmitters at chemical synapses. Our results revealed that Cx36 gene expression levels are lower in the retinas of rd/rd when compared with WT. Confocal analysis indicated that Cx36 immunolabeling almost disappeared in the outer plexiform layer without significant changes in protein distribution within the inner plexiform layer of rd/rd retinas. Likewise, synaptophysin expression remarkably decreased in the outer plexiform layer of rd/rd retinas, and this down-regulation was also associated with diminished transcript levels. Furthermore, we observed down-regulation of Cx57 gene expression in rd/rd retinas when compared with WT and also changes in protein distribution. Interestingly, Cx45 and synapsin I expression in rd/rd retinas showed no noticeable changes when compared with WT. Taken together, our results revealed that the loss of photoreceptors leads to decreased expression of some synaptic proteins. More importantly, this study provides evidence that neuronal activity regulates, but is not essential to maintain, the expression of synaptic elements.


Assuntos
Proteínas de Membrana/metabolismo , Células Fotorreceptoras/patologia , Retina/metabolismo , Degeneração Retiniana , Sinapses/metabolismo , Animais , Regulação da Expressão Gênica/fisiologia , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Degeneração Retiniana/metabolismo , Degeneração Retiniana/patologia , Degeneração Retiniana/fisiopatologia
8.
Br J Pharmacol ; 153(6): 1296-302, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18264118

RESUMO

BACKGROUND AND PURPOSE: Clostridium perfringens beta-toxin, an important agent of necrotic enteritis, causes plasma extravasation due to the release of a tachykinin NK(1) receptor agonist in mouse skin. In this study, we investigated the role of cytokines in beta-toxin-induced plasma extravasation. EXPERIMENTAL APPROACH: Male Balb/c, C3H/HeN and C3H/HeJ mice were anaesthetized with pentobarbitone and beta-toxin was injected i.d. into shaved dorsal skin. SR140333, capsaicin, chlorpromazine and pentoxifylline were given as pretreatment when required before the injection of the toxin. Cytokines in the dorsal skin were measured by ELISA. KEY RESULTS: Injection (i.d.) of beta-toxin induced a dose-dependent increase in dermal TNF-alpha and interleukin (IL)-1beta levels with a concomitant increase in plasma extravasation, but not the release of IL-6. SR140333 and capsaicin significantly inhibited the toxin-induced release of TNF-alpha and IL-1beta. The plasma extravasation and the release of TNF-alpha induced by beta-toxin were significantly inhibited by chlorpromazine and pentoxifylline which inhibit the release of TNF-alpha. The toxin-induced plasma extravasation in mouse skin was attenuated by pretreatment with a monoclonal antibody against TNF-alpha, but not anti-IL-1beta. Furthermore, the toxin caused an increase in plasma extravasation in both C3H/HeN (TLR4-intact) and C3H/HeJ (TLR4-deficient) mice. In C3H/HeN mice, the toxin-induced leakage was not inhibited by pretreatment with anti-TLR4/MD-2 antibody. CONCLUSIONS AND IMPLICATIONS: These observations show that beta-toxin-induced plasma extravasation in mouse skin is related to the release of TNF-alpha via the mechanism involving tachykinin NK(1) receptors, but not via TLR4.


Assuntos
Toxinas Bacterianas/toxicidade , Plasma/efeitos dos fármacos , Fator de Necrose Tumoral alfa/efeitos dos fármacos , Animais , Toxinas Bacterianas/administração & dosagem , Toxinas Bacterianas/farmacologia , Relação Dose-Resposta a Droga , Ensaio de Imunoadsorção Enzimática , Interleucina-1beta/efeitos dos fármacos , Interleucina-1beta/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Plasma/metabolismo , Receptores da Neurocinina-1/efeitos dos fármacos , Receptores da Neurocinina-1/metabolismo , Pele/efeitos dos fármacos , Pele/metabolismo , Receptor 4 Toll-Like/efeitos dos fármacos , Receptor 4 Toll-Like/metabolismo , Fator de Necrose Tumoral alfa/metabolismo
9.
Transbound Emerg Dis ; 65(1): e55-e62, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28710814

RESUMO

Rift Valley fever (RVF) is an acute mosquito-borne viral zoonosis whose outbreaks are often associated with prolonged rainfall and flooding, during which large numbers of vectors emerge. Recent studies into the inter-epidemic maintenance of RVF virus (RVFV) suggest that both vertical transmission in vectors and direct transmission between hosts act in combination with predisposing factors for persistence of the virus. A comparative longitudinal survey was carried out in Tana River County, Kenya, in irrigated, riverine and pastoral ecosystems from September 2014-June 2015. The objectives were to investigate the possibility of low-level RVFV transmission in these ecosystems during an inter-epidemic period (IEP), examine variations in RVFV seroprevalence in sheep and goats and determine the risk factors for transmission. Three hundred and sixteen small ruminants were selected and tested for immunoglobulin G antibodies against RVFV nucleoprotein using a competitive ELISA during six visits. Data on potential risk factors were also captured. Inter-epidemic RVFV transmission was evidenced by 15 seroconversions within the irrigated and riverine villages. The number of seroconversions was not significantly different (OR = 0.66, CI = 0.19-2.17, p = .59) between irrigated and riverine areas. No seroconversions were detected in the pastoral ecosystem. This study highlights the increased risk of inter-epidemic RVFV transmission posed by irrigation, through provision of necessary environmental conditions that enable vectors access to more breeding grounds, resting places and shade, which favour their breeding and survival.


Assuntos
Anticorpos Antivirais/sangue , Surtos de Doenças/veterinária , Mosquitos Vetores/virologia , Febre do Vale de Rift/epidemiologia , Vírus da Febre do Vale do Rift/imunologia , Animais , Ecossistema , Epidemias/veterinária , Feminino , Geografia , Imunoglobulina G/sangue , Quênia/epidemiologia , Estudos Longitudinais , Masculino , Febre do Vale de Rift/prevenção & controle , Febre do Vale de Rift/virologia , Vírus da Febre do Vale do Rift/isolamento & purificação , Fatores de Risco , Ruminantes/virologia , Soroconversão , Estudos Soroepidemiológicos , Zoonoses/epidemiologia
10.
Mol Biol Cell ; 12(11): 3690-702, 2001 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11694599

RESUMO

Double membrane structure, autophagosome, is formed de novo in the process of autophagy in the yeast Saccharomyces cerevisiae, and many Apg proteins participate in this process. To further understand autophagy, we analyzed the involvement of factors engaged in the secretory pathway. First, we showed that Sec18p (N-ethylmaleimide-sensitive fusion protein, NSF) and Vti1p (soluble N-ethylmaleimide-sensitive fusion protein attachment protein, SNARE), and soluble N-ethylmaleimide-sensitive fusion protein receptor are required for fusion of the autophagosome to the vacuole but are not involved in autophagosome formation. Second, Sec12p was shown to be essential for autophagy but not for the cytoplasm to vacuole-targeting (Cvt) (pathway, which shares mostly the same machinery with autophagy. Subcellular fractionation and electron microscopic analyses showed that Cvt vesicles, but not autophagosomes, can be formed in sec12 cells. Three other coatmer protein (COPII) mutants, sec16, sec23, and sec24, were also defective in autophagy. The blockage of autophagy in these mutants was not dependent on transport from endoplasmic reticulum-to-Golgi, because mutations in two other COPII genes, SEC13 and SEC31, did not affect autophagy. These results demonstrate the requirement for subgroup of COPII proteins in autophagy. This evidence demonstrating the involvement of Sec proteins in the mechanism of autophagosome formation is crucial for understanding membrane flow during the process.


Assuntos
Adenosina Trifosfatases , Autofagia/fisiologia , Proteínas de Transporte/metabolismo , Proteínas Fúngicas/metabolismo , Fusão de Membrana/fisiologia , Glicoproteínas de Membrana/metabolismo , Proteínas de Membrana/metabolismo , Fagossomos/fisiologia , Proteínas de Saccharomyces cerevisiae , Vacúolos/fisiologia , Proteínas de Transporte Vesicular , Vesículas Revestidas pelo Complexo de Proteína do Envoltório/metabolismo , Centrifugação com Gradiente de Concentração , Proteínas Fúngicas/fisiologia , Proteínas Ativadoras de GTPase , Fatores de Troca do Nucleotídeo Guanina , Glicoproteínas de Membrana/fisiologia , Proteínas Sensíveis a N-Etilmaleimida , Proteínas Qb-SNARE , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/fisiologia , Proteínas de Ligação a Fator Solúvel Sensível a N-Etilmaleimida
11.
J Int Med Res ; 34(2): 223-30, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16749419

RESUMO

Steroids inhibit primary wound healing and delay the formation of granulation tissue, but it has been controversial whether long-term steroid treatment by itself increases the risk of abdominal wound dehiscence. The aim of this study was to determine whether the pre-operative dose and post-operative total dose of steroids influence abdominal wound dehiscence. Of 28 patients who had surgery while receiving long-term steroid treatment, seven had abdominal wound dehiscence and 21 did not have dehiscence. The two groups differed significantly in the post-operative dose of steroids (404.3 +/- 147.1 and 135.6 +/- 118.7 mg, respectively) and the duration of wound healing (57.3 +/- 18.0 and 12.4 +/- 3.8 days), but no other differences were found. Abdominal wound dehiscence may be influenced by the post-operative rather than the pre-operative steroid dose.


Assuntos
Esteroides/efeitos adversos , Deiscência da Ferida Operatória/induzido quimicamente , Adolescente , Adulto , Idoso , Estudos de Casos e Controles , Relação Dose-Resposta a Droga , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cuidados Pós-Operatórios , Cuidados Pré-Operatórios , Esteroides/administração & dosagem , Fatores de Tempo , Cicatrização/efeitos dos fármacos
12.
Cancer Res ; 54(19): 5154-9, 1994 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-7923133

RESUMO

Chimeric toxins composed of transforming growth factor alpha (TGF alpha) fused to mutant forms of Pseudomonas exotoxin (PE) bind to the epidermal growth factor receptor and kill cells bearing epidermal growth factor receptors. Initially, the binding domain (Ia; amino acids 1-252) of PE was deleted and replaced with TGF alpha to make TGF alpha-PE40 in which TGF alpha is fused to domains II, Ib, and III of PE (amino acids 253-613). That drug is currently undergoing clinical study for the intravesical therapy of bladder cancer. To generate smaller molecules that would have increased tumor penetration, several deletion mutants were constructed. In one of these, TGF alpha was inserted near the carboxyl terminus of PE, and residues in domains II and Ib of PE (amino acids 253-279 and 365-380) were deleted so that the chimeric toxin did not need to be cleaved by an intracellular protease to be activated (Theuer et al., J. Biol. Chem., 267: 16872-16877, 1992). We have now constructed chimeric toxins which contain only domain III, yet still exhibit high cytotoxic activity on epidermal growth factor receptor-containing cells and produce substantial tumor regressions in mice bearing a human xenograft. The high cytotoxic activity of these severely truncated toxins provides new insights on the proposed functions of domains II and III of PE.


Assuntos
Antineoplásicos/farmacologia , Exotoxinas/farmacologia , Proteínas Recombinantes de Fusão/farmacologia , Fator de Crescimento Transformador alfa/farmacologia , Adenosina Difosfato Ribose/metabolismo , Animais , Sequência de Bases , Estabilidade de Medicamentos , Receptores ErbB/análise , Receptores ErbB/metabolismo , Exotoxinas/metabolismo , Exotoxinas/toxicidade , Feminino , Humanos , Camundongos , Camundongos Nus , Dados de Sequência Molecular , Neoplasias Experimentais/tratamento farmacológico , Relação Estrutura-Atividade , Fator de Crescimento Transformador alfa/metabolismo , Fator de Crescimento Transformador alfa/toxicidade
13.
Cancer Res ; 55(1): 71-7, 1995 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-7805044

RESUMO

The EGF-like domains of heregulin alpha, beta 1, beta 2, and beta 3 were fused to a truncated form of Pseudomonas exotoxin (PE38KDEL), which contains a modified carboxyl-terminal sequence, KDEL, that increases that toxin activity. The resulting chimeric toxins were produced in Escherichia coli, purified to near homogeneity, and shown to be cytotoxic to target cells with very high activity on HTB20, N-87 MCF-7, and HepG2 cells; high activity on A431 and MDA-MB468 cells; and low activity toward SK-OV3, L929, and KB cells. The fact that cytotoxicity did not correlate with the levels of erbB2 expression indicated that another receptor in the erb family might be involved. Accordingly, cytotoxicity assays were performed on NIH/3T3 cell lines transfected with EGFR, ErbB2, ErbB3, or ErbB4. The results indicate that the heregulin toxins target ErbB4 or possibly ErbB3 but not ErbB2.


Assuntos
Proteínas de Transporte/genética , Exotoxinas/farmacologia , Glicoproteínas/genética , Neuregulina-1 , Receptor ErbB-2/genética , Células 3T3 , Sequência de Aminoácidos , Animais , Sequência de Bases , Proteínas de Transporte/farmacologia , Escherichia coli/genética , Glicoproteínas/farmacologia , Camundongos , Dados de Sequência Molecular , Neurregulinas , Fosforilação , Pseudomonas/genética , Proteínas Recombinantes/farmacologia , Células Tumorais Cultivadas
14.
Biochim Biophys Acta ; 1454(1): 97-105, 1999 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-10354519

RESUMO

The beta-toxin gene isolated from Clostridium perfringens type B was expressed as a glutathione S-transferase (GST) fusion gene in Escherichia coli. The purified GST-beta-toxin fusion protein from the E. coli transformant cells was not lethal. The N-terminal amino acid sequence of the recombinant beta-toxin (r toxin) isolated by thrombin cleavage of the fusion protein was G-S-N-D-I-G-K-T-T-T. Biological activities and molecular mass of r toxin were indistinguishable from those of native beta-toxin (n toxin) purified from C. perfringens type C. Replacement of Cys-265 with alanine or serine by site-directed mutagenesis resulted in little loss of the activity. Treatment of C265A with N-ethylmaleimide (NEM), which inactivated lethal activity of r toxin and n toxin, led to no loss of the activity. The substitution of tyrosine or histidine for Cys-265 significantly diminished lethal activity. In addition, treatment of C265H with ethoxyformic anhydride which specifically modifies histidyl residue resulted in significant decrease in lethal activity, but that of r toxin with the agent did not. These results showed that replacement of the cysteine residue at position 265 with amino acids with large size of side chain or introduction of functional groups in the position resulted in loss of lethal activity of the toxin. Replacement of Tyr-266, Leu-268 or Trp-275 resulted in complete loss of lethal activity. Simultaneous administration of r toxin and W275A led to a decrease in lethal activity of beta-toxin. These observations suggest that the site essential for the activity is close to the cysteine residue.


Assuntos
Toxinas Bacterianas/química , Clostridium perfringens/patogenicidade , Compostos de Sulfidrila/química , Sequência de Aminoácidos , Animais , Toxinas Bacterianas/genética , Toxinas Bacterianas/toxicidade , Clostridium perfringens/genética , Cisteína/química , Expressão Gênica , Camundongos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Plasmídeos
15.
J Mol Biol ; 279(1): 175-88, 1998 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-9636708

RESUMO

Escherichia coli FtsH (HflB) is a membrane-bound and ATP-dependent zinc-metalloproteinase, which forms a complex with a pair of periplasmically exposed membrane proteins, HflK and HflC. It is the protease that degrades uncomplexed forms of the SecY subunit of protein translocase. Here, we characterized a new class of SecY-stabilizing mutation on the E. coli chromosome. The mutation (yccA11) is an internal deletion within a gene (yccA) known as an open reading frame for a hydrophobic protein with putative seven transmembrane segments. The YccA protein was found to be degraded in an FtsH-dependent manner in vivo and in vitro, whereas the YccA11 mutant protein, lacking eight amino acid residues within the amino-terminal cytoplasmic domain, was refractory to the degradation. The yccA11 mutation exhibited partial dominance when overexpressed. Cross-linking, co-immunoprecipitation, and histidine tagging experiments showed that YccA11 as well as YccA can associate with both the FtsH and the HflKC proteins. Thus, the mutant YccA protein appeared to compete with SecY for recognition by the FtsH proteolytic system and the residues deleted by the yccA mutation are required for the initiation of proteolysis by FtsH. Interestingly, the inhibitory action of YccA11 was mediated by HflKC, since the deletion of hflK-hflC suppressed the yccA11 phenotype. The yccA11 mutation stabilized subunit a of the proton ATPase F0 segment as well, but not the CII protein of bacteriophage lambda or the sigma 32 protein. From these results we suggest that there are at least two pathways for FtsH-dependent protein degradation, only one of which (probably for membrane proteins) is subject to the HflKC-dependent interference by the YccA11 mutant substrate.


Assuntos
Proteínas de Bactérias/metabolismo , Endopeptidases/metabolismo , Proteínas de Escherichia coli , Escherichia coli/enzimologia , Proteínas de Membrana/metabolismo , Proteases Dependentes de ATP , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Sequência de Bases , Escherichia coli/genética , Proteínas de Membrana/genética , Dados de Sequência Molecular , Mutação , Fenótipo , Canais de Translocação SEC , Especificidade por Substrato
16.
Clin Cancer Res ; 4(4): 993-1004, 1998 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9563895

RESUMO

Growth factor receptors provide unique opportunities for development of targeted anticancer therapy. Members of the type I receptor tyrosine kinase family, including epidermal growth factor (EGF) receptor (EGFR) and ErbB-2/neu, are often overexpressed in various human cancer cells, including breast. Recently, it has been shown that both ErbB-3 and ErbB-4 are receptors for heregulin (HRG)/Neu differentiation factor. Eight chimeric toxins composed of the extracellular and EGF-like domains of four different HRG isoforms and truncated Pseudomonas exotoxin (PE38KDEL) were constructed. The fusion proteins exhibited activity similar to the native HRG in inducing ErbB receptors phosphorylation. The EGF-like domain of HRG13 and HRGbeta2 fused to PE38KDEL showed the highest cytotoxic activity, with a IC50 of < or = 0.001 ng/ml. The alpha isoforms that were fused to PE38KDEL were 100-fold less active than the beta isoforms. The HRG-Pseudomonas exotoxin (PE) toxins show extremely high activity against cells expressing ErbB-4 receptor, alone or together with other members of the ErbB receptor family. Cells that do not express ErbB-4 but express ErbB-3 receptor, together with the ErbB-2 or EGFR, exhibited moderate sensitivity to HRG-PE toxins. HRG-PE toxins have little or no activity against cells expressing EGFR, ErbB-2, or ErbB-3 alone. More than an 80% tumor regression was achieved by intratumor injection of 1 microg of fusion proteins per day for 5 days. Continuous i.p. administration of EGF-like domain of HRGbeta1-PE38KDEL for 7 days via a miniosmotic pump at a dose of 40 microg/kg/day inhibited the growth of ErbB-4 receptor positive but not ErbB-4 receptor negative cell lines in athymic nude mice. We conclude that there is therapeutic potential of HRG-PE toxins in the therapy of cancers overexpressing the ErbB-4 or ErbB-2 plus ErbB-3 receptors.


Assuntos
Antineoplásicos/farmacologia , Receptores ErbB/efeitos dos fármacos , Exotoxinas/farmacologia , Genes erbB/efeitos dos fármacos , Glicoproteínas/farmacologia , Proteínas Proto-Oncogênicas/efeitos dos fármacos , Animais , Antineoplásicos/farmacocinética , Antineoplásicos/uso terapêutico , Carcinoma/tratamento farmacológico , Ensaio de Unidades Formadoras de Colônias , Exotoxinas/farmacocinética , Exotoxinas/uso terapêutico , Feminino , Glicoproteínas/farmacocinética , Glicoproteínas/uso terapêutico , Humanos , Imunotoxinas/farmacocinética , Imunotoxinas/farmacologia , Imunotoxinas/uso terapêutico , Camundongos , Camundongos Nus , Fosforilação , Receptor ErbB-3 , Proteínas Recombinantes de Fusão/farmacocinética , Proteínas Recombinantes de Fusão/farmacologia , Proteínas Recombinantes de Fusão/uso terapêutico , Neoplasias Gástricas/tratamento farmacológico , Células Tumorais Cultivadas/efeitos dos fármacos , Tirosina/metabolismo
17.
Int J Tuberc Lung Dis ; 19(10): 1176-81, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26459529

RESUMO

OBJECTIVE: To determine gender differences in treatment outcomes among 15-49 year olds with smear-positive pulmonary tuberculosis (PTB) and factors associated with poor outcomes in Kenya. DESIGN: Retrospective descriptive cohort. RESULTS: Of 16 056 subjects analysed, 38% were female and 62% male. Females had a higher risk of poor treatment outcome than males (12% vs. 10%, P < 0.001; adjusted OR 1.29, 95%CI 1.16-1.44, P < 0.001). In the first multivariate model, restricting the analysis to human immunodeficiency virus (HIV) positive patients and adjusting for risk factors and clustering, females had a non-significantly lower risk of poor outcome (OR 0.99, 95%CI 0.86-1.13, P = 0.844). In the model restricted to HIV-negative patients, a non-significantly lower risk was found (OR 0.89, 95%CI 0.73-1.09, P = 0.267). In the second model, restricting analysis to patients on antiretroviral therapy (ART) and adjusting for risk factors and clustering, females had a non-significantly lower risk of poor PTB treatment outcomes (OR 0.98, 95%CI 0.84-1.14, P = 0.792). In the model restricted to HIV-positive patients not on ART, a non-significantly higher risk was found (OR 1.15, 95%CI 0.79-1.67, P = 0.461). CONCLUSION: Females of reproductive age are likely to have poorer treatment outcomes than males. Among females, not commencing ART during anti-tuberculosis treatment seemed to be associated with poor outcomes.


Assuntos
Fármacos Anti-HIV/uso terapêutico , Antituberculosos/uso terapêutico , Infecções por HIV/epidemiologia , Tuberculose Pulmonar/tratamento farmacológico , Adolescente , Adulto , Feminino , Infecções por HIV/tratamento farmacológico , Humanos , Quênia , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Estudos Retrospectivos , Fatores de Risco , Fatores Sexuais , Escarro/microbiologia , Resultado do Tratamento , Tuberculose Pulmonar/diagnóstico , Tuberculose Pulmonar/microbiologia , Adulto Jovem
18.
Public Health Action ; 5(1): 23-9, 2015 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-26400598

RESUMO

SETTING: A rural private health facility, Ruby Medical Centre (RMC), participating in a safe motherhood health voucher system for poor women in Kiambu County, Kenya. OBJECTIVES: Between 2007 and 2013, to determine 1) the number of women who delivered at the RMC, their characteristics and pregnancy-related outcomes, and 2) the number of women who received an incomplete antenatal care (ANC) package and associated factors. DESIGN: Retrospective cross-sectional study using routine programme data. RESULTS: During the study period, 2635 women delivered at the RMC: 50% were aged 16-24 years, 60% transferred in from other facilities and 59% started ANC in the third trimester of pregnancy. Of the 2635 women, 1793 (68%) received an incomplete ANC package: 347 (13%) missed essential blood tests, 312 (12%) missed the tetanus toxoid immunisation and 1672 (65%) had fewer than four visits. Presenting late and starting ANC elsewhere were associated with an incomplete package. One pregnancy-related mortality occurred; the stillbirth rate was 10 per 1000 births. CONCLUSION: This first assessment of the health voucher system in rural Kenya showed problems in ANC quality. Despite favourable pregnancy-related outcomes, increased efforts should be made to ensure earlier presentation of pregnant women, comprehensive ANC, and more consistent and accurate monitoring of reproductive indicators and interventions.


Contexte : Une structure de santé privée rurale, le Ruby Medical Centre (RMC), participant à un système de bons de traitement de Maternité sans risques destiné à des femmes pauvres du conté de Kiambu au Kenya.Objectifs : Entre 2007 et 2013, déterminer 1) le nombre de femmes qui ont accouché au RMC, leurs caractéristiques et le devenir de leur grossesse, et 2) le nombre ne bénéficiant que d'un paquet de soins anténataux (ANC) incomplets et les facteurs associés.Schéma : Etude rétrospective transversale basée sur les données recueillies en routine dans les programmes.Résultats : Au cours de la période d'étude, 2635 femmes ont accouché au RMC : 50% étaient âgées de 16 à 24 ans, 60% avaient été transférées d'autres structures et 59% avaient débuté les ANC au cours du 3e trimestre. De ces 2635 femmes, 1793 (68%) avaient un paquet d'ANC incomplet : 347 (13%) ont manqué les principaux tests sanguins, 312 (12%) n'ont pas eu de vaccination anti-tétanique et 1672 (65%) ont eu moins de quatre consultations. Un démarrage tardif et des ANC débutés ailleurs étaient associés à un paquet d'ANC incomplet. Un décès lié à la grossesse est survenu et le taux de mortinatalité a été de 10/1000 naissances.Conclusion : Cette première évaluation du système de bons de traitement dans les zones rurales du Kenya a mis en évidence des problèmes de qualité des ANC. En dépit de l'évolution favorable des grossesses, il est nécessaire d'accroitre les efforts pour faire venir les femmes enceintes plus tôt, offrir des ANC complets et un suivi plus cohérent et précis des indicateurs et des interventions de santé reproductive.


Marco de referencia: El Ruby Medical Centre (RMC) es un centro de atención de salud privado en zona rural, que participa en el sistema de cupones por una maternidad sin riesgo en el condado de Kiambu, en Kenia.Objetivos: Determinar entre el 2007 y el 2013: 1) la cantidad de mujeres cuyo parto se atendió en el RMC, las características de las mujeres y los desenlaces relacionados con el embarazo; y 2) el número de mujeres que recibieron una atención prenatal (ANC) incompleta y los factores asociados con esta situación.Métodos: Fue este un estudio transversal retrospectivo a partir de los datos del programa corriente.Resultados: Durante el período del estudio, se atendió el parto de 2635 mujeres en el RMC, el 50% de las cuales tenía entre 16 y 24 años de edad, el 60% acudió como remisión de otros centros de atención y el 59% había comenzado la ANC durante el tercer trimestre del embarazo. De las 2635 mujeres, 1793 recibieron una ANC incompleta (68%) a saber: en 347 no se practicaron los principales exámenes sanguíneos (13%); 312 no recibieron la vacuna con el toxoide antitetánico (12%); y 1672 acudieron a menos de cuatro citas de control (65%). Los factores asociados con una ANC incompleta fueron una presentación tardía al programa y el inicio de la ANC en un centro diferente. Se presentó un caso de mortalidad relacionada con el embarazo y la tasa de mortinatalidad fue de 10 por 1000 nacimientos.Conclusión: El presente estudio es la primera evaluación del sistema de cupones por una maternidad sin riesgo en la zona rural de Kenia y puso en evidencia problemas en materia de calidad de la ANC. Pese a los desenlaces favorables del embarazo, se precisan iniciativas que fomenten una presentación más temprana de las embarazadas al programa, la ANC integral, y una vigilancia más regular y exacta de los indicadores y las intervenciones en materia de salud reproductiva.

19.
Neuroscience ; 284: 247-259, 2015 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-25305666

RESUMO

Neonatal anoxia in rodents has been used to understand brain changes and cognitive dysfunction following asphyxia. This study investigated the time-course of cellular and subcellular changes and hippocampal cell death in a non-invasive model of anoxia in neonatal rats, using Terminal deoxynucleotidyl transferase-mediated dUTP Nick End Labeling (TUNEL) to reveal DNA fragmentation, Fluoro-Jade® B (FJB) to show degenerating neurons, cleaved caspase-3 immunohistochemistry (IHC) to detect cells undergoing apoptosis, and transmission electron microscopy (TEM) to reveal fine ultrastructural changes related to cell death. Anoxia was induced by exposing postnatal day 1 (P1) pups to a flow of 100% gaseous nitrogen for 25 min in a chamber maintained at 37 °C. Control rats were similarly exposed to this chamber but with air flow instead of nitrogen. Brain changes following anoxia were evaluated at postnatal days 2, 14, 21 and 60 (P2, P14, P21 and P60). In addition, spatial reference memory following anoxia and control treatments was evaluated in the Morris water maze, starting at P60. Compared to their respective controls, P2 anoxic rats exhibited (1) higher TUNEL labeling in cornus ammonis (CA) 1 and the dentate gyrus (DG), (2) higher FJB-positive cells in the CA2-3, and (3) somato-dendritic swelling, mitochondrial injury and chromatin condensation in irregular bodies, as well as other subcellular features indicating apoptosis, necrosis, autophagy and excitotoxicity in the CA1, CA2-3 and DG, as revealed by TEM. At P14, P21 and P60, both groups showed small numbers of TUNEL-positive and FJB-positive cells. Stereological analysis at P2, P14, P21 and P60 revealed a lack of significant differences in cleaved caspase-3 IHC between anoxic and control subjects. These results suggest that the type of hippocampal cell death following neonatal anoxia is likely independent of caspase-3 activation. Neonatal anoxia induced deficits in acquisition and performance of spatial reference memory in the Morris water maze task. Compared to control subjects, anoxic animals exhibited increased latencies and path lengths to reach the platform, as well as decreased searching specifically for the platform location. In contrast, no significant differences were observed for swimming speeds and frequency within the target quadrant. Together, these behavioral results indicate that the poorer performance by anoxic subjects is related to spatial memory deficits and not to sensory or motor deficits. Therefore, this model of neonatal anoxia in rats induces hippocampal changes that result in cell losses and impaired hippocampal function, and these changes are likely related to spatial memory deficits in adulthood.


Assuntos
Morte Celular/fisiologia , Hipocampo/fisiopatologia , Hipóxia/fisiopatologia , Memória Espacial/fisiologia , Animais , Animais Recém-Nascidos , Asfixia Neonatal , Caspase 3/metabolismo , Modelos Animais de Doenças , Hipocampo/patologia , Hipóxia/patologia , Masculino , Aprendizagem em Labirinto/fisiologia , Ratos Wistar
20.
FEBS Lett ; 399(1-2): 26-8, 1996 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-8980112

RESUMO

Escherichia coli FtsH is a membrane-bound ATPase with a proteolytic activity against the SecY subunit of protein translocase. We now report that subunit a of the membrane-embedded Fo part of H+-ATPase is another substrate of FtsH. Pulse-chase experiments showed that subunit a is unstable when it alone (without Fo subunits b and c) was oversynthesized and that it is stabilized in the ftsH mutants. Selective and ATP-dependent degradation of subunit a by purified FtsH protein was demonstrated in vitro. These results suggest that FtsH serves as a quality-control mechanism to avoid potentially harmful accumulation of free subunit a in the membrane.


Assuntos
Proteínas de Bactérias/metabolismo , Escherichia coli/metabolismo , Proteínas de Membrana/metabolismo , ATPases Translocadoras de Prótons/metabolismo , Proteases Dependentes de ATP , Proteínas de Escherichia coli , Hidrólise , ATPases Translocadoras de Prótons/química , Especificidade por Substrato
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