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1.
BMC Pulm Med ; 22(1): 384, 2022 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-36258160

RESUMO

BACKGROUND: The difference in diagnostic yield between surgical lung biopsy and transbronchial lung cryobiopsy (TBLC) in diffuse parenchymal lung diseases (DPLD) has been reported to be due to differences in the rate of interpathologist agreement, specimen size, and specimen adequacy. In TBLC, the specimens containing large airway components are generally believed as inadequate specimens for histological evaluation, but the detailed characteristics of TBLC specimens including the large airway and the impact on histological diagnostic rates of DPLD have not been investigated. METHODS: We retrospectively reviewed the specimen characteristics of patients with DPLD who underwent TBLC. RESULTS: Between February 2018 and January 2020, 74 patients and 177 specimens were included. There were 85 (48.0%) large airway specimens (LAS) that contained bronchial gland or bronchial cartilage. The ideal specimen ratio was significantly lower in the LAS-positive group than that in the LAS-negative group (5.8% vs. 45.6%), and the proportion of bronchioles, alveoli, and perilobular area were similarly lower in the LAS-positive group. The presence of traction bronchiectasis and diaphragm overlap sign on high-resolution computed tomography (HRCT) were also significantly higher in the LAS-positive group than those in the LAS-negative group. We observed a statistically significant trend in histological diagnostic yield (40.7% in LAS positive group; 60.8% in LAS positive and negative group; 91.6% in LAS negative group) (Cochran-Armitage trend test). CONCLUSION: LAS is a specimen often collected in TBLC and contains a low percentage of bronchioles, alveoli, and perilobular area. Since the histological diagnostic yield tends to be higher in cases that do not contain LAS, it may be important to determine the biopsy site that reduces the frequency of LAS collection by referring to the HRCT findings in TBLC.


Assuntos
Broncoscopia , Doenças Pulmonares Intersticiais , Humanos , Broncoscopia/métodos , Estudos Retrospectivos , Doenças Pulmonares Intersticiais/diagnóstico , Doenças Pulmonares Intersticiais/patologia , Pulmão/diagnóstico por imagem , Pulmão/patologia , Biópsia/métodos
2.
BMC Pulm Med ; 20(1): 84, 2020 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-32252718

RESUMO

BACKGROUND: Pulmonary alveolar proteinosis (PAP) is characterized by the accumulation of surfactant proteins within the alveolar spaces. Autoimmune PAP (APAP) caused by elevated levels of GM-CSF autoantibodies (GM-Ab) is very rarely associated with systemic autoimmune disease. Here we report a case of APAP manifested during immunosuppressive treatment for polymyositis with interstitial lung disease. CASE PRESENTATION: A 52-year-old woman treated at our hospital because of polymyositis with interstitial pneumonia had maintained remission by immunosuppressive treatment for 15 years. She had progressive dyspnea subsequently over several months with her chest CT showing ground-glass opacities (GGO) in bilateral geographic distribution. Her bronchoalveolar lavage fluid with cloudy appearance revealed medium-sized foamy macrophages and PAS-positive amorphous eosinophilic materials by cytological examination. We diagnosed her as APAP due to an increased serum GM-CSF autoantibody level. Attenuating immunosuppression failed to lead GGO improvement, but whole lung lavage (WLL) was effective in her condition. CONCLUSIONS: PAP should be considered as one of the differential diseases when the newly interstitial shadow was observed during immunosuppressive treatment. WLL should be regarded as the treatment option for APAP concurred in connective tissue disease (CTD).


Assuntos
Autoanticorpos/sangue , Doenças Autoimunes/diagnóstico , Doenças Pulmonares Intersticiais/complicações , Polimiosite/complicações , Proteinose Alveolar Pulmonar/diagnóstico , Doenças Autoimunes/imunologia , Doenças Autoimunes/fisiopatologia , Líquido da Lavagem Broncoalveolar/citologia , Dispneia/etiologia , Feminino , Fator Estimulador de Colônias de Granulócitos e Macrófagos/imunologia , Humanos , Imunossupressores/efeitos adversos , Pulmão/fisiopatologia , Doenças Pulmonares Intersticiais/tratamento farmacológico , Pessoa de Meia-Idade , Polimiosite/tratamento farmacológico , Proteinose Alveolar Pulmonar/imunologia , Proteinose Alveolar Pulmonar/fisiopatologia , Proteinose Alveolar Pulmonar/terapia , Tomografia Computadorizada por Raios X
3.
Nat Mater ; 16(11): 1100-1105, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28825731

RESUMO

The transition of a Mott insulator to metal, the Mott transition, can occur via carrier doping by elemental substitution, and by photoirradiation, as observed in transition-metal compounds and in organic materials. Here, we show that the application of a strong electric field can induce a Mott transition by a new pathway, namely through impulsive dielectric breakdown. Irradiation of a terahertz electric-field pulse on an ET-based compound, κ-(ET) 2Cu[N(CN) 2]Br (ET:bis(ethylenedithio)tetrathiafulvalene), collapses the original Mott gap of ∼30 meV with a ∼0.1 ps time constant after doublon-holon pair productions by quantum tunnelling processes, as indicated by the nonlinear increase of Drude-like low-energy spectral weights. Additionally, we demonstrate metallization using this method is faster than that by a femtosecond laser-pulse irradiation and that the transition dynamics are more electronic and coherent. Thus, strong terahertz-pulse irradiation is an effective approach to achieve a purely electronic Mott transition, enhancing the understanding of its quantum nature.

4.
Phys Rev Lett ; 118(10): 107602, 2017 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-28339244

RESUMO

A rapid polarization control in paraelectric materials is important for an ultrafast optical switching useful in the future optical communication. In this study, we applied terahertz-pump second-harmonic-generation-probe and optical-reflectivity-probe spectroscopies to the paraelectric neutral phase of an organic molecular dielectric, tetrathiafulvalene-p-chloranil and revealed that a terahertz pulse with the electric-field amplitude of ∼400 kV/cm produces in the subpicosecond time scale a large macroscopic polarization whose magnitude reaches ∼20% of that in the ferroelectric ionic phase. Such a large polarization generation is attributed to the intermolecular charge transfers and breathing motions of domain walls between microscopic neutral and ionic domains induced by the terahertz electric field.

5.
Nat Commun ; 12(1): 953, 2021 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-33574221

RESUMO

Ultrafast electronic-phase change in solids by light, called photoinduced phase transition, is a central issue in the field of non-equilibrium quantum physics, which has been developed very recently. In most of those phenomena, charge or spin orders in an original phase are melted by photocarrier generations, while an ordered state is usually difficult to be created from a non-ordered state by a photoexcitation. Here, we demonstrate that a strong terahertz electric-field pulse changes a Mott insulator of an organic molecular compound in κ-(ET)2Cu[N(CN)2]Cl (ET = bis(ethylenedithio)tetrathiafulvalene), to a macroscopically polarized charge-order state; herein, electronic ferroelectricity is induced by the collective intermolecular charge transfers in each dimer. In contrast, in an isostructural compound, κ-(ET)2Cu2(CN)3, which shows the spin-liquid state at low temperatures, a similar polar charge order is not stabilized by the same terahertz pulse. From the comparative studies of terahertz-field-induced second-harmonic-generation and reflectivity changes in the two compounds, we suggest the possibility that a coupling of charge and spin degrees of freedom would play important roles in the stabilization of polar charge order.

6.
Sci Adv ; 5(6): eaav2187, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31187057

RESUMO

Coupling of charge and spin degrees of freedom is a critical feature of correlated electron oxides, as represented by the spin-related mechanism of a Cooper pair under high-T c superconductivity. A doublon-holon pair generated on an antiferromagnetic spin background is also predicted to attract each other via the spin-spin interaction J, similar to a Cooper pair, while its evidence is difficult to obtain experimentally. Here, we investigate such an excitonic effect by electroreflectance spectroscopy using terahertz electric field pulses in undoped cuprates: Nd2CuO4, Sr2CuO2Cl2, and La2CuO4. Analyses of the spectral changes of reflectivity under electric fields reveal that the splitting of odd-parity and even-parity excitons, a measure of doublon-holon binding energy, increases with J. This trend is reproduced by t-J-type model calculations, providing strong evidence of the spin-related doublon-holon pairing. Agreement with the calculations supports the s-wave symmetry of the doublon-holon pair in contrast to the d-wave Cooper pair in doped cuprates.

8.
Sci Rep ; 8(1): 15014, 2018 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-30301914

RESUMO

Rapid polarization control by an electric field in ferroelectrics is important to realize high-frequency modulation of light, which has potential applications in optical communications. To achieve this, a key strategy is to use an electronic part of ferroelectric polarization. A hydrogen-bonded molecular ferroelectric, croconic acid, is a good candidate, since π-electron polarization within each molecule is theoretically predicted to play a significant role in the ferroelectric-state formation, as well as the proton displacements. Here, we show that a sub-picosecond polarization modulation is possible in croconic acid using a terahertz pulse. The terahertz-pulse-pump second-harmonic-generation-probe and optical-reflectivity-probe spectroscopy reveal that the amplitude of polarization modulation reaches 10% via the electric-field-induced modifications of π-electron wavefunctions. Moreover, the measurement of electric-field-induced changes in the infrared molecular vibrational spectrum elucidates that the contribution of proton displacements to the polarization modulation is negligibly small. These results demonstrate the electronic nature of polarization in hydrogen-bonded molecular ferroelectrics. The ultrafast polarization control via π-electron systems observed in croconic acid is expected to be possible in many other hydrogen-bonded molecular ferroelectrics and utilized for future high-speed optical-modulation devices.

9.
IEEE Int Conf Rehabil Robot ; 2017: 19-24, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28813787

RESUMO

Standing-up motion is an important daily activity. It has been known that elderly and post-stroke patients have difficulty in performing standing-up motion. The standing-up motion is retrained by therapists to maximize independence of the elderly and post-stroke patients, but it is not clear how the elderly and post-stroke patients control their redundant muscles to achieve standing-up motion. This study employed the concept of muscle synergy to analyze how healthy young adults, healthy elderly people and post-stroke patients control their muscles. Experimental result verified that four muscle synergies can represent human standing-up motion. In addition, it indicated that the post-stroke patients shift the weights of muscle synergies to finish standing-up motion comparing to healthy subjects. Moreover, different muscle synergy structures were associated with the CoM and joint kinematics.


Assuntos
Fenômenos Biomecânicos/fisiologia , Músculo Esquelético/fisiologia , Equilíbrio Postural/fisiologia , Acidente Vascular Cerebral/fisiopatologia , Adulto , Idoso , Humanos , Pessoa de Meia-Idade , Adulto Jovem
10.
J Neurol Neurosurg Psychiatry ; 77(9): 1025-9, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16788009

RESUMO

BACKGROUND: Although the aetiology of moyamoya disease (MMD) has not been fully clarified, genetic analysis of familial MMD (F-MMD) has considerable potential to disclose it. OBJECTIVE: To determine the inheritance pattern and clinical characteristics of F-MMD to enable precise genetic analyses of the disease. METHODS: 15 highly aggregated Japanese families (52 patients; 38 women and 14 men) with three or more affected members were examined. The difference in categories of age at onset (child onset, adult onset and asymptomatic) between paternal and maternal transmission was compared by chi2 statistics. RESULTS: In all families there had been three or more generations without consanguinity, and all types of transmission, including father-to-son, were observed. Among a total of 135 offspring of affected people, 59 (43.7%) were patients with MMD or obligatory carriers. Affected mothers were more likely to produce late-onset (adult-onset or asymptomatic) female offspring (p = 0.007). CONCLUSIONS: The mode of inheritance of F-MMD is autosomal dominant with incomplete penetrance. Thus, in future genetic studies on F-MMD, parametric linkage analyses using large families with an autosomal dominant mode of inheritance are recommended. Genomic imprinting may be associated with the disease.


Assuntos
Genes Dominantes , Doença de Moyamoya/genética , Adolescente , Adulto , Idade de Início , Idoso , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Linhagem , Penetrância
11.
J Natl Cancer Inst ; 68(3): 401-5, 1982 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-6950167

RESUMO

Of 1,749 volunteers in a screening program for gastric cancer in Japan, 206 men and 181 women received a systematic gastroscopic examination and responded to a dietary questionnaire estimating their quantitative intake of 33 food items during the past weeks. When diet was correlated with intestinal metaplasia (a precursor lesion of gastric carcinoma) found in gastroscopic biopsies, it was observed that more dried fish consumption and less vitamin A intake increased the extent of intestinal metaplasia in men. For women, there was a significant negative association of ume (pickled plum) intake with intestinal metaplasia. The implications of these findings were discussed in relation to gastric cancer.


Assuntos
Dieta/efeitos adversos , Intestinos/patologia , Metaplasia/epidemiologia , Lesões Pré-Cancerosas/epidemiologia , Adulto , Fatores Etários , Idoso , Reações Falso-Negativas , Feminino , Humanos , Japão , Masculino , Metaplasia/etiologia , Pessoa de Meia-Idade , Risco , Fatores Sexuais , Neoplasias Gástricas/diagnóstico , Neoplasias Gástricas/epidemiologia
12.
Cancer Res ; 50(22): 7358-63, 1990 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-2224863

RESUMO

Human lung tumor-derived cell lines with low passage generation were transplanted into nude mice to determine their growth behavior and invasive potential. Six cell lines (HKT-2, HKT-3, HKT-5, HKT-6, HKT-7, HKT-8) were inoculated into deepithelialized rat trachea (5 x 10(5) cells/trachea). After cell inoculation, the tracheas were sealed and transplanted into the subcutis of nude mice. In a parallel experiment, these cell lines (1 x 10(6) cells) were injected s.c. In the subcutis, the tumor take rate of HKT-3, the lowest of all, was only 13% with a long latency period of 18 weeks, and 3 cell lines (HKT-2, HKT-3, HKT-7) did not show any invasive growth to the surrounding tissue. In rat tracheas, all cell lines proliferated within 3 weeks, and 4 of them (HKT-2, HKT-5, HKT-6, HKT-8) showed invasive growth to the tracheal wall within 1-2 weeks. Cells growing in the tracheal wall showed higher [3H]thymidine labeling indexes and greater atypia, such as larger nuclei and prominent nucleoli, than those in the tracheal lumen. The s.c. tumor take rate correlated with the incidence of invasive growth to the tracheal wall. The survival of the patients originally bearing the six tumors also correlated closely with the invasive potential of this system. These results indicate that the system using low passage cell lines can evaluate the invasive potential shortly after the inoculation of a relatively small number of cells and can be used as a clinically reliable biological invasion assay.


Assuntos
Adenocarcinoma/patologia , Carcinoma de Células Escamosas/patologia , Neoplasias Pulmonares/patologia , Metástase Neoplásica , Traqueia/patologia , Animais , Divisão Celular , Tecido Conjuntivo/patologia , DNA/biossíntese , Humanos , Camundongos , Camundongos Nus , Transplante de Neoplasias , Ratos , Traqueia/transplante , Transplante Heterólogo , Células Tumorais Cultivadas
13.
Cancer Res ; 57(9): 1630-3, 1997 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-9134997

RESUMO

We previously identified two commonly deleted regions on chromosome bands 10q25-q26 in endometrial cancer: an 8-cM region and a 12-cM region. In the present study, we further studied the 8-cM region with 83 endometrial cancer specimens and 14 microsatellite markers and narrowed it down to a 1-cM region between D10S587 and D10S1723. This result was confirmed by two-color fluorescence in situ hybridization analysis. An association between histopathologically lower grade tumor and allelic loss (P = 0.03 by Fisher's exact test) was also observed. We also constructed a yeast artificial chromosome (YAC) contig and found that one YAC clone, which was 790 kb in size, harbored the whole 1-cM region of common allelic loss.


Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 10 , Neoplasias do Endométrio/genética , Genes Supressores de Tumor , Alelos , Mapeamento Cromossômico , Feminino , Marcadores Genéticos , Humanos , Hibridização in Situ Fluorescente , Repetições de Microssatélites
14.
Cancer Res ; 39(2 Pt 1): 328-31, 1979 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-761204

RESUMO

Some workers have associated fecal bile acids with colon cancer frequency. They suggest that the risk for colon cancer increases with a rise in the level of total and degraded fecal bile acids. The Japanese in Hawaii, who are at high risk for this cancer, had higher concentrations of deoxycholic acid (a degraded bile acid) in their fecal specimens than did the people in Akita, Japan, who are at low risk. However, the findings for the other bile acids were unremarkable or inconsistent. These data were suggestive, but not strongly supportive, of a relationship between fecal bile acid patterns and colon cancer risk.


Assuntos
Ácidos e Sais Biliares/análise , Neoplasias do Colo/etiologia , Fezes/análise , Adulto , Idoso , Ácido Desoxicólico/análise , Dieta , Métodos Epidemiológicos , Feminino , Havaí , Humanos , Japão/etnologia , Masculino , Pessoa de Meia-Idade , Risco
15.
Sci Rep ; 6: 20571, 2016 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-26864779

RESUMO

In electronic-type ferroelectrics, where dipole moments produced by the variations of electron configurations are aligned, the polarization is expected to be rapidly controlled by electric fields. Such a feature can be used for high-speed electric-switching and memory devices. Electronic-type ferroelectrics include charge degrees of freedom, so that they are sometimes conductive, complicating dielectric measurements. This makes difficult the exploration of electronic-type ferroelectrics and the understanding of their ferroelectric nature. Here, we show unambiguous evidence for electronic ferroelectricity in the charge-order (CO) phase of a prototypical ET-based molecular compound, α-(ET)2I3 (ET:bis(ethylenedithio)tetrathiafulvalene), using a terahertz pulse as an external electric field. Terahertz-pump second-harmonic-generation(SHG)-probe and optical-reflectivity-probe spectroscopy reveal that the ferroelectric polarization originates from intermolecular charge transfers and is inclined 27° from the horizontal CO stripe. These features are qualitatively reproduced by the density-functional-theory calculation. After sub-picosecond polarization modulation by terahertz fields, prominent oscillations appear in the reflectivity but not in the SHG-probe results, suggesting that the CO is coupled with molecular displacements, while the ferroelectricity is electronic in nature. The results presented here demonstrate that terahertz-pump optical-probe spectroscopy is a powerful tool not only for rapidly controlling polarizations, but also for clarifying the mechanisms of ferroelectricity.

16.
Oncogene ; 19(31): 3508-20, 2000 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-10918609

RESUMO

Ceramide has recently been regarded as a potential mediator of apoptosis. In the present study, the effects of Bcl-2 and Bax on the ceramide-mediated apoptotic pathways were examined in glioma cells overexpressing Bcl-2 or Bax. Etoposide, cisplatin and tumor necrosis factor-alpha induced apoptosis of C6 rat glioma cells which was associated with ceramide formation due to activation of neutral sphingomyelinase, followed by release of mitochondrial cytochrome c into the cytosol and activation of caspases-9 and -3. The growth of C6 cells stably overexpressing either Bcl-2 or Bax was almost equal to that of the vector-transfected cells. Bax overexpression enhanced etoposide-induced apoptosis through acceleration of cytochrome c release and caspases activation. However, Bax had no effect on ceramide formation. Similar findings were obtained in C6 cells and U87-MG human glioblastoma cells which were transiently overexpressed with Bax. In contrast, Bcl-2 overexpression resulted in a retardation of the apoptotic process via prevention of cytochrome c release and caspases activation, and ceramide formation was also blocked when Bcl-2 was highly overexpressed in glioma cells. In addition, transient overexpression of Bcl-xL also exerted inhibitory effects on ceramide formation and apoptotic cell death induced by etoposide. These results indicate that Bax promotes apoptosis regardless of ceramide formation and that Bcl-2 or Bcl-xL prevents ceramide formation by repressing neutral sphingomyelinase as well as ceramide-induced cytochrome c release. Oncogene (2000) 19, 3508 - 3520


Assuntos
Apoptose/genética , Neoplasias Encefálicas/patologia , Ceramidas/fisiologia , Regulação Neoplásica da Expressão Gênica , Glioblastoma/patologia , Glioma/patologia , Proteínas de Neoplasias/fisiologia , Proteínas Proto-Oncogênicas c-bcl-2/fisiologia , Proteínas Proto-Oncogênicas/fisiologia , Animais , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/metabolismo , Caspases/metabolismo , Cisplatino/farmacologia , Meios de Cultura Livres de Soro/farmacologia , Grupo dos Citocromos c/metabolismo , Ativação Enzimática , Etoposídeo/farmacologia , Genes bcl-2 , Glioblastoma/genética , Glioblastoma/metabolismo , Glioma/genética , Glioma/metabolismo , Humanos , Mitocôndrias/enzimologia , Proteínas de Neoplasias/biossíntese , Proteínas de Neoplasias/genética , Proteínas Proto-Oncogênicas/biossíntese , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas c-bcl-2/biossíntese , Proteínas Proto-Oncogênicas c-bcl-2/genética , Ratos , Proteínas Recombinantes de Fusão/fisiologia , Esfingomielina Fosfodiesterase/metabolismo , Transfecção , Células Tumorais Cultivadas/efeitos dos fármacos , Células Tumorais Cultivadas/metabolismo , Células Tumorais Cultivadas/patologia , Fator de Necrose Tumoral alfa/farmacologia , Proteína X Associada a bcl-2 , Proteína bcl-X
17.
Oncogene ; 20(11): 1368-78, 2001 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-11313880

RESUMO

The present study was designed to elucidate the relationship between p53 and ceramide, both of which are involved in apoptotic signaling. Treatment of human glioma cells with etoposide caused apoptosis only in cells expressing functional p53. p53 activation was followed by the formation of reactive oxygen species (ROS), superoxide anion (O2-*) measured by hydroethidium oxidation into ethidium and hydrogen peroxide (H2O2) measured by oxidation of 2',7'-dichlorofluorescin (DCFH) into 2',7'-dichlorofluorescein (DCF), which was accompanied with ceramide generation through the activation of neutral, but not acid, sphingomyelinase. Superoxide dismutase (SOD), a selective antioxidant for O2-*, had no effects on p53 expression but inhibited ceramide generation and apoptotic cell death caused by etoposide. However, catalase, a specific antioxidant for H2O2, only weakly inhibited and sodium formate, a hydroxyl radical (* OH) scavenger, unaffected etoposide-induced apoptosis. Like etoposide-induced cell death, treatment of glioma cells with the O2-*-releasing agent, pyrogallol, induced typical apoptosis and ceramide generation even in the presence of catalase. In contrast, human glioma cells lacking functional p53, either due to mutation or the expression of E6 protein of human papillomavirus, were highly resistant to etoposide and exhibited no significant change in the ceramide level. Moreover, expression of functional p53 protein in glioma cells expressing mutant p53 using a temperature-sensitive human p53(Val138) induced ceramide accumulation by the activation of neutral sphingomyelinase which was dependent on the generation of O2-*. Taken together, these results suggest that p53 may modulate ceramide generation by activation of neutral sphingomyelinase through the formation of O2-*, but not its downstream compounds H2O2 or * OH.


Assuntos
Ceramidas/biossíntese , Glioma/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Esfingomielina Fosfodiesterase/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Apoptose , Etoposídeo/farmacologia , Regulação da Expressão Gênica , Humanos , Pirogalol/farmacologia , Superóxidos/metabolismo , Proteína Supressora de Tumor p53/genética
18.
Cell Death Differ ; 7(9): 761-72, 2000 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11042671

RESUMO

Etoposide (VP-16) a topoisomerase II inhibitor induces apoptosis of tumor cells. The present study was designed to elucidate the mechanisms of etoposide-induced apoptosis in C6 glioma cells. Etoposide induced increased formation of ceramide from sphingomyelin and release of mitochondrial cytochrome c followed by activation of caspase-9 and caspase-3, but not caspase-1. In addition, exposure of cells to etoposide resulted in decreased expression of Bcl-2 with reciprocal increase in Bax protein. z-VAD.FMK, a broad spectrum caspase inhibitor, failed to suppress the etoposide-induced ceramide formation and change of the Bax/Bcl-2 ratio, although it did inhibit etoposide-induced death of C6 cells. Reduced glutathione or N-acetylcysteine, which could reduce ceramide formation by inhibiting sphingomyelinase activity, prevented C6 cells from etoposide-induced apoptosis through blockage of caspase-3 activation and change of the Bax/Bcl-2 ratio. In contrast, the increase in ceramide level by an inhibitor of ceramide glucosyltransferase-1, D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol caused elevation of the Bax/Bcl-2 ratio and potentiation of caspase-3 activation, thereby resulting in enhancement of etoposide-induced apoptosis. Furthermore, cell-permeable exogenous ceramides (C2- and C6-ceramide) induced downregulation of Bcl-2, leading to an increase in the Bax/Bcl-2 ratio and subsequent activation of caspases-9 and -3. Taken together, these results suggest that ceramide may function as a mediator of etoposide-induced apoptosis of C6 glioma cells, which induces increase in the Bax/Bcl-2 ratio followed by release of cytochrome c leading to caspases-9 and -3 activation.


Assuntos
Apoptose , Caspases/metabolismo , Ceramidas/biossíntese , Etoposídeo/farmacologia , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Animais , Apoptose/fisiologia , Bioensaio , Caspase 3 , Inibidores de Caspase , Ceramidas/metabolismo , Ceramidas/farmacologia , Fragmentação do DNA , Ativação Enzimática , Humanos , Mitocôndrias/enzimologia , Mitocôndrias/metabolismo , Inibidores da Síntese de Ácido Nucleico/farmacologia , RNA Mensageiro/metabolismo , Ratos , Transdução de Sinais , Esfingomielina Fosfodiesterase/metabolismo , Fatores de Tempo , Células Tumorais Cultivadas , Proteína X Associada a bcl-2
19.
J Am Coll Cardiol ; 29(3): 613-22, 1997 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-9060901

RESUMO

OBJECTIVES: The aim of this study was to examine the left ventricular mechanoenergetic effects of a novel Ca2+ sensitizing agent, MCI-154, on diseased human hearts compared with dobutamine. BACKGROUND: Unlike conventional cardiotonic agents, a Ca2+ sensitizer that could produce a positive inotropic action by altering the responsiveness of myofilament to Ca2+ could generate force with smaller amounts of Ca2+; thus, it may potentially save energy expenditure. METHODS: The left ventricular pressure-volume relation and myocardial oxygen consumption per beat (Vo2) were measured by a conductance (volume) catheter and a Webster catheter. Left ventricular contractility (Emax), systolic pressure-volume area (PVA [index of left ventricular total mechanical energy]) and Vo2 were assessed before and after infusion of MCI-154 or dobut-amine. The PVA-independent Vo2 (Vo2 mainly for excitation-contraction coupling) was assessed as the Vo2 at zero PVA. RESULTS: Both agents increased Emax comparably (dobutamine: from 3.55 +/- 1.10 [mean +/- SD] to 5.04 +/- 1.16 mm Hg/ml per m2, p < 0.0001; MCI-154: from 3.36 +/- 1.26 to 5.37 +/- 2.14 mm Hg/ml per m2, p < 0.0001); dobutamine increased total Vo2 (from 0.22 +/- 0.08 to 0.27 +/- 0.09 ml O2, p < 0.05) and PVA-independent Vo2 (from 0.019 +/- 0.019 to 0.091 +/- 0.051 ml O2, p < 0.005); but MCI-154 did not change these variables significantly. Consequently, the oxygen cost of contractility (delta PVA-independent Vo2/delta Emax) was less with MCI-154 than with dobutamine (0.14 +/- 0.18 vs. 1.10 +/- 0.80 J/mm Hg per ml per m2, p < 0.05). CONCLUSIONS: These results suggest that the cardiotonic action mediated by MCI-154 could provide an energetic advantage over the conventional cardiotonic action with currently used inotropic agents.


Assuntos
Cardiotônicos/farmacologia , Doença das Coronárias/fisiopatologia , Consumo de Oxigênio/efeitos dos fármacos , Piridazinas/farmacologia , Função Ventricular Esquerda/efeitos dos fármacos , Idoso , Constrição Patológica , Dobutamina/farmacologia , Metabolismo Energético , Feminino , Hemodinâmica/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Contração Miocárdica/fisiologia , Miocárdio/metabolismo , Pressão Ventricular/efeitos dos fármacos
20.
J Mol Biol ; 184(2): 319-29, 1985 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-4032481

RESUMO

Recent experimental data of Shore & Baldwin (1983b) and of Horowitz & Wang (1984) for the apparent twisting coefficient K, which determines the breadth of the Gaussian distribution of DNA topoisomers with different linking numbers N, show that the product of K and nbp (the number of base-pairs) is nearly a constant for nbp approximately greater than 2000, but that it increases sharply with decreasing nbp for nbp approximately less than 2000. The main purpose of the present paper is to explain theoretically such behavior of K as a function of nbp. Thus the statistical mechanics of DNA topoisomers in general is developed on the basis of a twisted worm-like chain, i.e. a special case of the helical worm-like chain. The previous treatments of the N-dependent ring-closure probability, i.e. the distribution of N, which are valid only for small chain length L, are extended to the range of larger L. The variance of N is then shown to be exactly the sum of those of the writhe Wr and the twist Tw. For small values of L, the distribution of Wr is not Gaussian, and its variance or moment (Wr2) increases rather steeply with increasing L. With these and known Monte Carlo results for freely jointed chains, an empirical interpolation formula for (Wr2) is also constructed to be valid for all values of L. It predicts that (Wr2)/L increases monotonically, with increasing L to its coil-limiting value. On the other hand, the distribution of N is actually Gaussian in the practical range of N for all values of L. The conditional distribution of Wr with N fixed is also evaluated. Finally, K is expressed in terms of the torsional constant C, the stiffness parameter lambda-1 (which is equal to the Kuhn segment length and twice the persistence length for this special case), and (Wr2). The derived equation predicts that nbpK decreases monotonically to its coil-limiting value with increasing nbp. This decrease arises from the fluctuation in Wr and its neglect leads to an underestimate of C by 7 to 10%, even for short DNA with nbp approximately equal to 200. From an analysis of the experimental data of the two groups, the estimates of C = 3.1 to 3.2 X 10(-19) erg cm and lambda-1 = 1000 to 1200 A are obtained.


Assuntos
DNA , Conformação de Ácido Nucleico , Isomerismo , Matemática , Método de Monte Carlo , Probabilidade , Estatística como Assunto
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