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Visually impaired children do Orientation and Mobility(O&M) training to acquire the abilities to walk alone with white cane. The abilities to walk alone are to discriminate sound sources, localize sound sources, recognizer sound motion or echoes, and form a mental map. A mental map is a map formed in the brain, and visually impaired people create a map mainly from sound information. Walking without sight is dangerous, so many assistants are needed during O&M training. However, due to the shortage of O&M specialists, the time which visually impaired children do O&M training is becoming shorter. Therefore, we developed an O&M training system on a map created in a Virtual Reality (VR) space to eliminate the danger and alarm which visually impaired children feel during O&M training, and to enable safe and secure O&M training with fewer assistants.
Assuntos
Encéfalo , Realidade Virtual , Humanos , Criança , Emoções , Movimento (Física) , SomRESUMO
[Purpose] We describe a new method of functional electrical stimulation therapy for severe hemiparesis. Conventional functional electrical stimulation of the lower legs has limited applications. It is only suitable for patients who can monitor their muscle contractions, and it has complicated equipment installation procedures. [Participant and Methods] The participant was a male in his 40s with severe motor paralysis following brain surgery. We monitored the participant's healthy side using the external assist mode of an Integrated Volitional Control Electrical Stimulation (IVES® OG Giken, Okayama, Japan) system while forcibly contracting the paralyzed side. The participant received this new functional electrical stimulation therapy five times per week. [Results] Two weeks after initiation of therapy, paralysis was noticeably improved, and motor function was maintained for approximately 1â year. [Conclusion] The outcomes of this case suggest that the addition of forced contraction therapy, mirror therapy, and repetitive exercise therapy to regular physical therapy may be beneficial. This treatment method may also be useful in postoperative patients with central motor palsy and no muscle contraction ability.
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[Purpose] This study aimed to evaluate the improvement in lower extremity hemiplegia following brain tumor operation with an integrated volitional control electrical stimulator (IVES). [Participant and Methods] A 40â year-old male with anaplasic oligodendroglioma in the right frontal lobe underwent IVES in the rectus femoris and tibialis anterior muscles using the power-assist and sensor-trigger modes. Lower extremity motor function was assessed before and after the therapy sessions. An assessment was conducted using various techniques, including static posturography and surface electromyography. [Results] Static posturography showed an improvement in the center of pressure and sway area after IVES gait training. Based on a time-series statistical parametric mapping analysis, the activation pattern of each muscle after the treatment was different. Muscle synergy analysis revealed decreased total variance accounted for by a single synergy in the affected and normal sides after the treatment. [Conclusion] Patients with chronic hemiplegic lower extremity impairment responded well to IVES gait training. Electromyography-triggered functional electrical stimulation may enhance sensory-motor integration. Proprioceptive feedback plays a crucial role in improving motor control.
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Koji molds, such as Aspergillus oryzae and Aspergillus sojae, are used in the food industry in East Asia and have been explored for the large-scale production of extracellular hydrolases. We previously found that the deletion of a gene encoding a putative GT2 glycosyltransferase increased production of extracellular hydrolases in A. sojae. The gene was named rseA (regulator of the secretory enzyme A). We predicted that intracellular signaling pathways were involved in the increased production of hydrolases in the ΔrseA mutant of A. sojae. However, little has been reported on molecular biological knowledge about A. sojae. Hence, Aspergillus nidulans, a typical model organism used in molecular biology, was employed for the functional characterization of rseA in this study. Deletion of the rseA ortholog in A. nidulans induced increased extracellular production of hydrolases under the solid-state cultivation condition, similar to that in A. sojae. The involvement of the cell wall integrity pathway and the high osmolarity glycerol pathway in ΔrseA was further investigated. The results indicated that the HOG pathway played an important role in the increased extracellular production of hydrolases caused by the deletion of the rseA gene. rseA ortholog in A. nidulans was identical to cpsA, which was reported to function as a regulator of mycotoxin production, morphogenesis, and cell wall biosynthesis. However, this is the first study reporting that rseA/cpsA regulates extracellular hydrolase production in A. nidulans.
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Aspergillus nidulans/genética , Glicerol/metabolismo , Glicosiltransferases/genética , Hidrolases/metabolismo , Aspergillus/enzimologia , Aspergillus/genética , Aspergillus nidulans/metabolismo , Parede Celular/metabolismo , Meios de Cultura/química , Espaço Extracelular/enzimologia , Espaço Extracelular/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Deleção de Genes , Glicosiltransferases/metabolismo , Hidrolases/genética , Engenharia Metabólica/métodos , Redes e Vias Metabólicas/genética , Técnicas Microbiológicas , Organismos Geneticamente Modificados , Concentração Osmolar , Via Secretória/genéticaRESUMO
Muscle atrophy and cachexia are common comorbidities among patients suffering from cancer, chronic obstructive pulmonary disease, and several other chronic diseases. The peptide hormone ghrelin exerts pleiotropic effects including the stimulation of growth hormone secretion and subsequent increase of insulin-like growth factor-1 levels, an important mediator of muscle growth and repair. Ghrelin also acts on inflammation, appetite, and adipogenesis and therefore has been considered a promising therapeutic target for catabolic conditions. We previously reported on the synthesis and properties of an indane based series of ghrelin receptor full agonists which led to a sustained increase of insulin-like growth factor-1 in a dog pharmacodynamic study. Herein we report on the identification of a series of pyrrolidine or piperidine based full agonists and attempted optimization to give compounds with profiles suitable for progression as clinical candidates.
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Desenho de Fármacos , Pirrolidinas/química , Pirrolidinas/farmacologia , Receptores de Grelina/agonistas , Animais , Cães , Células HEK293 , Humanos , Pirrolidinas/farmacocinética , RatosRESUMO
Cachexia and muscle wasting are very common among patients suffering from cancer, chronic obstructive pulmonary disease, and other chronic diseases. Ghrelin stimulates growth hormone secretion via the ghrelin receptor, which subsequently leads to increase of IGF-1 plasma levels. The activation of the GH/IGF-1 axis leads to an increase of muscle mass and functional capacity. Ghrelin further acts on inflammation, appetite, and adipogenesis and for this reason was considered an important target to address catabolic conditions. We report the synthesis and properties of an indane based series of ghrelin receptor full agonists; they have been shown to generate a sustained increase of IGF-1 levels in dog and have been thoroughly investigated with respect to their functional activity.
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Indanos/química , Indanos/farmacologia , Receptores de Grelina/agonistas , Animais , Células HEK293 , Humanos , Indanos/farmacocinética , Masculino , Modelos Moleculares , Conformação Proteica , Ratos , Receptores de Grelina/químicaRESUMO
The bile salt export pump (BSEP) plays an important role in biliary secretion. Mutations in ABCB11, the gene encoding BSEP, induce progressive familial intrahepatic cholestasis type 2 (PFIC2), which presents with severe jaundice and liver dysfunction. A less severe phenotype, called benign recurrent intrahepatic cholestasis type 2, is also known. About 200 missense mutations in ABCB11 have been reported. However, the phenotype-genotype correlation has not been clarified. Furthermore, the frequencies of ABCB11 mutations differ between Asian and European populations. We report a patient with PFIC2 carrying a homozygous ABCB11 mutation c.386G>A (p.C129Y) that is most frequently reported in Japan. The pathogenicity of BSEPC129Y has not been investigated. In this study, we performed the molecular analysis of this ABCB11 mutation using cells expressing BSEPC129Y. We found that trafficking of BSEPC129Y to the plasma membrane was impaired and that the expression of BSEPC129Y on the cell surface was significantly lower than that in the control. The amount of bile acids transported via BSEPC129Y was also significantly lower than that via BSEPWT. The transport activity of BSEPC129Y may be conserved because the amount of membrane BSEPC129Y corresponded to the uptake of taurocholate into membrane vesicles. In conclusion, we demonstrated that c.386G>A (p.C129Y) in ABCB11 was a causative mutation correlating with the phenotype of patients with PFIC2, impairment of biliary excretion from hepatocytes, and the absence of canalicular BSEP expression in liver histological assessments. Mutational analysis in ABCB11 could facilitate the elucidation of the molecular mechanisms underlying the development of intrahepatic cholestasis.
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Membro 11 da Subfamília B de Transportadores de Cassetes de Ligação de ATP/genética , Colestase Intra-Hepática/diagnóstico , Colestase Intra-Hepática/genética , Estudos de Associação Genética , Mutação , Fenótipo , Membro 11 da Subfamília B de Transportadores de Cassetes de Ligação de ATP/química , Membro 11 da Subfamília B de Transportadores de Cassetes de Ligação de ATP/metabolismo , Alelos , Linhagem Celular , Progressão da Doença , Feminino , Hepatócitos/metabolismo , Homozigoto , Humanos , Masculino , Modelos Moleculares , Conformação Proteica , Análise de Sequência de DNARESUMO
[Purpose] There are no reliable evidences that the weakening of intrinsic foot muscles causes the decrease of the medial longitudinal arch (MLA) height. The purpose of this study was to confirm whether the fatigue of intrinsic foot muscles decrease the MLA height during standing and gait using 3D motion analysis system. [Subjects and Methods] Twenty healthy male subjects participated in this study. Foot kinematics was measured using an Oxford Foot Model before and after fatigue-inducing exercises of the abductor hallucis and flexor hallucis brevis muscles. [Results] Following fatigue-inducing exercise, in both standing and gait, the MLA height did not decrease but slightly increased. In addition, the reduction of a rear foot eversion angle was noted. [Conclusion] Fatigue of the abductor hallucis and flexor hallucis brevis muscles did not cause a change associated with collapsing of the MLA during both standing and gait. This suggested that the MLA support force from these muscles would be compensated by other MLA support structures, such as extrinsic foot muscles.
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Extracellular matrix (ECM) stiffness regulates the lineage commitment of mesenchymal stem cells (MSCs). Although cells sense ECM stiffness through focal adhesions, how cells sense ECM stiffness and regulate ECM stiffness-dependent differentiation remains largely unclear. In this study, we show that the cytoskeletal focal adhesion protein vinculin plays a critical role in the ECM stiffness-dependent adipocyte differentiation of MSCs. ST2 mouse MSCs differentiate into adipocytes and osteoblasts in an ECM stiffness-dependent manner. We find that a rigid ECM increases the amount of cytoskeleton-associated vinculin and promotes the nuclear localization and activity of the transcriptional coactivator paralogs Yes-associated protein (YAP, also known as YAP1) and transcriptional coactivator with a PDZ-binding motif (TAZ, also known as WWTR1) (hereafter YAP/TAZ). Vinculin is necessary for enhanced nuclear localization and activity of YAP/TAZ on the rigid ECM but it does not affect the phosphorylation of the YAP/TAZ kinase LATS1. Furthermore, vinculin depletion promotes differentiation into adipocytes on rigid ECM, while it inhibits differentiation into osteoblasts. Finally, TAZ knockdown was less effective at promoting adipocyte differentiation in vinculin-depleted cells than in control cells. These results suggest that vinculin promotes the nuclear localization of transcription factor TAZ to inhibit the adipocyte differentiation on rigid ECM.
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Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Adipócitos/citologia , Adipócitos/metabolismo , Diferenciação Celular , Núcleo Celular/metabolismo , Matriz Extracelular/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Vinculina/metabolismo , Actinas/metabolismo , Animais , Fenômenos Biomecânicos , Soluções Tampão , Linhagem Celular , Citoesqueleto/metabolismo , Técnicas de Silenciamento de Genes , Humanos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Camundongos , Transporte Proteico , Transativadores , Fatores de Transcrição , Proteínas com Motivo de Ligação a PDZ com Coativador TranscricionalRESUMO
The power of rhodium-carbene methodology in chemistry is demonstrated by the synthesis of a structurally complex polyazole antibiotic. Plantazolicinâ A, a novel soil-bacterium metabolite, comprises a linear array of 10 five-membered rings in two pentacyclic regions that derive from ribosomal peptide synthesis followed by extensive posttranslational modification. The compound possesses potent antimicrobial activity, and is selectively active against the anthrax-causing organism. A conceptually different synthesis of plantazolicinâ A is reported in which the key steps are the use of rhodium(II)-catalyzed reactions of diazocarbonyl compounds to generate up to six of the seven oxazole rings of the antibiotic. NMR spectroscopic studies and molecular modeling reveal a likely dynamic hairpin conformation with a hinge region around the two isoleucine residues. The compound has modest activity against methicillin-resistant Staphylococcus aureus (MRSA).
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Antibacterianos/síntese química , Antibacterianos/farmacologia , Azóis/química , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Oligopeptídeos/síntese química , Oligopeptídeos/farmacologia , Polímeros/química , Antibacterianos/química , Azóis/farmacologia , Catálise , Relação Dose-Resposta a Droga , Metano/análogos & derivados , Metano/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Oligopeptídeos/química , Polímeros/farmacologia , Ródio/química , Relação Estrutura-AtividadeRESUMO
Wnt activation by inhibiting glycogen synthase kinase 3 (GSK-3) causes bone anabolism in rodents making GSK-3 a potential therapeutic target for osteoporotic and osteolytic metastatic bone disease. To understand the wnt pathway related to human disease translation, the ability of 3 potent inhibitors of GSK-3 (AZD2858, AR79, AZ13282107) to 1) drive osteoblast differentiation and mineralisation using human adipose-derived stem cells (hADSC) in vitro; and 2) stimulate rat bone formation in vivo was investigated. Bone anabolism/resorption was determined using clinically relevant serum biomarkers as indicators of bone turnover and bone formation assessed in femurs by histopathology and pQCT/µCT imaging. GSK-3 inhibitors caused ß-catenin stabilisation in human and rat mesenchymal stem cells, stimulated hADSC commitment towards osteoblasts and osteogenic mineralisation in vitro. AZD2858 produced time-dependent changes in serum bone turnover biomarkers and increased bone mass over 28 days exposure in rats. After 7 days, AZD2858, AR79 or AZ13282107 exposure increased the bone formation biomarker P1NP, and reduced the resorption biomarker TRAcP-5b, indicating increased bone anabolism and reduced resorption in rats. This biomarker profile was differentiated from anabolic agent PTH1-34 or the anti-resorptive Alendronate-induced changes. Increased bone formation in cortical and cancellous bone as assessed by femur histopathology supported biomarker changes. 14 day AR79 treatment increased bone mineral density and trabecular thickness, and decreased trabecular number and connectivity assessed by pQCT/µCT. GSK-3 inhibition caused hADSC osteoblastogenesis and mineralisation in vitro. Increased femur bone mass associated with changes in bone turnover biomarkers confirmed in vivo bone formation and indicated uncoupling of bone formation and resorption.
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Remodelação Óssea/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Células-Tronco Mesenquimais/efeitos dos fármacos , Osteoblastos/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Animais , Biomarcadores/sangue , Densidade Óssea/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Inibidores Enzimáticos/química , Feminino , Fêmur/efeitos dos fármacos , Fêmur/metabolismo , Fêmur/patologia , Humanos , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/enzimologia , Estrutura Molecular , Osteoblastos/citologia , Osteoblastos/enzimologia , Ratos , Ratos Sprague-DawleyRESUMO
BACKGROUND: Clinical observation of Epstein-Barr virus (EBV) status has not documented in childhood cancer survivors (CCSs) sustaining long-term remission of malignant diseases. Thus, the aim of this study was to evaluate the EBV status in children with various malignant diseases after they completed their treatments. PATIENTS AND METHODS: Thirty consecutive children with various malignant diseases previously received treatment at the University of Tsukuba Hospital. Nine cases had acute lymphoblastic leukemia (ALL), 10 had solid tumors, 4 had lymphoma, 4 had CNS tumors, and 3 had acute myeloid leukemia (AML). EBV DNA in 328 whole blood samples were monitored by real-time QPCR for all cases after treatment. Clinical records and laboratory data were also reviewed. RESULTS: There were 6/30 (20%) cases with continuous detection of EBV DNA while there were 24/30 (80%) cases without continuous EBV DNA. EBV DNAemia was persistently observed in 4/9 (44.4%) cases with ALL and in 2/4 (50%) cases with lymphoma. Persistent EBV DNAemia can be observed for >5 years without any EBV associated symptoms or diseases. CONCLUSIONS: Childhood cancer survivors have persistent EBV DNAemia more frequently, which is thought to be observed in cases with ALL and lymphoma with higher tendency for >5 years after treatment. Persistent EBV DNAemia is frequent in CCSs aged 5-10 years. Any immunological alteration is speculative in a pathophysiology of persistent EBV DNAemia.
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DNA Viral/genética , Infecções por Vírus Epstein-Barr/virologia , Herpesvirus Humano 4/genética , Neoplasias/virologia , Sobreviventes , Adolescente , Criança , Pré-Escolar , DNA Viral/sangue , Infecções por Vírus Epstein-Barr/diagnóstico , Infecções por Vírus Epstein-Barr/imunologia , Feminino , Seguimentos , Humanos , Masculino , Neoplasias/mortalidade , Neoplasias/terapia , Prognóstico , Reação em Cadeia da Polimerase em Tempo Real , Estudos Retrospectivos , Taxa de Sobrevida , Carga ViralRESUMO
We report the discovery of novel series of highly potent TLR7 agonists based on 8-oxoadenines, 1 and 2 by introducing and optimizing various tertiary amines onto the N(9)-position of the adenine moiety. The introduction of the amino group resulted in not only improved water solubility but also enhanced TLR7 agonistic activity. In particular compound 20 (DSR-6434) indicated an optimal balance between the agonistic potency and high water solubility. It also demonstrated a strong antitumor effect in vivo by intravenous administration in a tumor bearing mice model.
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Adenina/análogos & derivados , Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Receptor 7 Toll-Like/agonistas , Água/química , Adenina/administração & dosagem , Adenina/síntese química , Adenina/química , Adenina/farmacologia , Administração Intravenosa , Animais , Antineoplásicos/administração & dosagem , Linhagem Celular Tumoral , Modelos Animais de Doenças , Células HEK293 , Humanos , Camundongos , Estrutura Molecular , SolubilidadeRESUMO
Systemic administration of a Toll-like receptor 7 (TLR7) agonist is effective to in suppressing Th2 derived inflammation, however systemic induction of various cytokines such as IL-6, IL-12, and type I interferon (IFN) is observed. This cytokine induction would be expected to cause flu-like symptoms. We have previously reported adenine compounds (3, 4) as interferon inducing agents acting as TLR7 agonists. To identify potent anti-inflammatory compounds without systemic side effects, a labile carboxylic ester as an antedrug functionality onto the N(9)-benzyl group of the adenine was introduced. We found that 9e was a potent TLR7 agonist (EC(50) 50 nM) and rapidly metabolized by human plasma (T(1/2) 2.6 min) to the pharmacologically much less active carboxylic acid 16. Intratracheal administration of 9e effectively inhibited allergen-induced airway inflammation without inducing cytokines systemically. Therefore, the TLR7 agonist with antedrug characteristics 9e (SM-324405) is a novel candidate for immunotherapy of allergic diseases.
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Adenina/análogos & derivados , Receptor 7 Toll-Like/agonistas , Adenina/efeitos adversos , Adenina/síntese química , Adenina/farmacologia , Adenina/uso terapêutico , Animais , Ácidos Carboxílicos/química , Linhagem Celular , Estabilidade de Medicamentos , Humanos , Hipersensibilidade/metabolismo , Hipersensibilidade/terapia , Imunoterapia , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Interferons/biossíntese , Masculino , Ratos , Receptor 7 Toll-Like/metabolismoRESUMO
Transfusion-related acute lung injury (TRALI) is characterized by pulmonary edema and hypoxemia within 6 hours of transfusion in the absence of other causes of acute lung injury or circulatory overload and is now considered the leading cause of transfusion-related death. We report a female patient who showed hypoxemia after transfusion without any other causes of acute lung injury. The patient is a 43-year-old woman, who received emergency transurethral hemostasis for bladder hemorrhage with hematuria and low hemoglobin concentration (3.2 g x dl(-1)). General anesthesia was maintained with sevoflurane, remifentanil, and vecuronium. Two units of RBC were transfused during operation. Since she showed high blood pressure, tachycardia, and a painful expression after operation, we extubated her. Although we gave her O2 6 l x min(-1) after extubation, she showed low oxygen saturation (90%), thus we started bag-mask ventilation. However, she complained of dyspnea and the chest X-ray revealed bilateral diffuse pulmonary edema following hypoxemia (80%). Thus we inserted endotracheal tube and started positive pressure assist ventilation. The next day, hypoxemia was improved under PEEP therapy. The anti-HLA antibody in the transfused plasma was positive. We conclude that the early recognition and management of TRALI is essential during and after operation.
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Síndrome do Desconforto Respiratório/etiologia , Reação Transfusional , Adulto , Anestesia Geral , Feminino , Humanos , Respiração com Pressão PositivaRESUMO
BACKGROUND: Many studies have shown that regional anesthesia improves postoperative outcome and particularly lessens infection by attenuating perioperative immunosuppression related to the stress response to surgery and general anesthesia. However, it remains to be determined whether regional anesthesia improves oncologic outcome after surgery. METHODS: C57BL/6 mice were subjected to laparotomy during sevoflurane general anesthesia alone or combined with spinal block achieved with bupivacaine (5 microg) and morphine (1.25 microg). Control groups were anesthetized only or were untreated. Liver was removed 5 h after surgery to assess antitumor killer cell activity and production of interferon gamma and interleukin 4 by liver mononuclear cells, or mice were inoculated intravenously with liver-metastatic EL4 cells and hepatic metastases were counted 12 days later. RESULTS: Laparotomy during sevoflurane anesthesia significantly increased the number (+/- SD) of liver metastases from 15.5 +/- 8.7 (control) and 19.4 +/- 5.4 (sevoflurane alone) to 33.7 +/- 8.9. Sevoflurane anesthesia plus spinal block significantly reduced this increase to 19.8 +/- 9. The in vitro killer activity of liver mononuclear cells against EL4 cells decreased from 32.7% (control) and 29.4% (sevoflurane alone) to 18.5% after sevoflurane plus laparotomy, and the addition of spinal block increased activity to 26.6%. The interferon-gamma/interleukin-4 ratio decreased from 89.3 (control) and 95.7 (anesthesia alone) to 15.7 after sevoflurane plus laparotomy, and the addition of spinal block increased the ratio to 46.5. CONCLUSIONS: The addition of spinal block to sevoflurane general anesthesia accompanying surgery attenuates the suppression of tumoricidal function of liver mononuclear cells, presumably by preserving the T helper 1/T helper 2 (Th1/Th2) balance, and thereby reduces the promotion of tumor metastasis.
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Anestésicos Combinados/farmacologia , Citocinas/metabolismo , Neoplasias Hepáticas Experimentais/prevenção & controle , Fígado/patologia , Linfoma de Células T/tratamento farmacológico , Metástase Neoplásica/prevenção & controle , Linfócitos T Auxiliares-Indutores/efeitos dos fármacos , Analgésicos Opioides/farmacologia , Anestesia Geral/métodos , Raquianestesia/métodos , Anestésicos Inalatórios/farmacologia , Anestésicos Locais/farmacologia , Animais , Bupivacaína/farmacologia , Interferon gama/biossíntese , Interferon gama/efeitos dos fármacos , Interleucina-4/biossíntese , Células Matadoras Naturais/efeitos dos fármacos , Células Matadoras Naturais/imunologia , Fígado/imunologia , Neoplasias Hepáticas Experimentais/imunologia , Neoplasias Hepáticas Experimentais/secundário , Linfoma de Células T/imunologia , Masculino , Éteres Metílicos/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Morfina/farmacologia , Transplante de Neoplasias , Bloqueio Nervoso/métodos , Sevoflurano , Linfócitos T Auxiliares-Indutores/imunologia , Células Tumorais CultivadasRESUMO
Eph receptors and ephrin ligands are membrane-bound cell-cell communication molecules with well-defined functions in development, but their expression patterns and functions in many adult tissues are still largely unknown. We have detected substantial levels of the EphB2 and EphB6 receptors and the ephrin-B1 ligand in the adult mouse kidney by RT-PCR amplification. Immunolocalization experiments revealed that EphB2 is localized in the tubules of the inner and outer medulla and EphB6 is in the tubules of the outer medulla and cortex. By contrast, ephrin-B1 was detected in tubules throughout the whole nephron. Consistent with the overlapping expression of the EphB2 receptor and the ephrin-B1 ligand in the medulla, EphB2 is tyrosine-phosphorylated, and therefore activated, in the kidney. In the outer medulla, however, EphB2 signaling may be attenuated by the co-expressed kinase-inactive EphB6 receptor. Interestingly, we found that EphB signaling induces RhoA activation and Rac1 inactivation as well as cell retraction, enlargement of focal adhesions and prominent stress fibers in primary cultures of medullary tubule cells. These results suggest that EphB receptor signaling through Rho family GTPases regulates the cytoarchitecture and spatial organization of the tubule cells in the adult kidney medulla and, therefore, may affect the reabsorption ability of the kidney.