Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 52
Filtrar
1.
Appl Opt ; 59(13): D95-D103, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32400633

RESUMO

When a circular aperture is uniformly illuminated, it is possible to observe in the far field an image of a bright circle surrounded by faint rings known as the Airy pattern or Airy disk. This pattern is described by the first-order Bessel function of the first type divided by its argument expressed in circular coordinates. We introduce the higher-order Bessel functions with a vortex azimuthal factor to propose a family of functions to generalize the function defining the Airy pattern. These functions, which we call vortex Jinc functions, happen to form an orthogonal set. We use this property to investigate their usefulness in fitting various surfaces in a circular domain, with applications in precision optical manufacturing, wavefront optics, and visual optics, among others. We compare them with other well-known sets of orthogonal functions, and our findings show that they are suitable for these tasks and can pose an advantage when dealing with surfaces that concentrate a considerable amount of their information near the center of a circular domain, making them suitable applications in visual optics or analysis of aberrations of optical systems, for instance, to analyze the point spread function.

2.
J Parasitol ; 104(5): 574-575, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30019983

RESUMO

We provide the first report of Acanthocephala ( Prosthenorchis elegans) in Mexican non-human primates. There has been no known treatment against this parasite except for surgical removal, and this has been relatively ineffective because of the small juveniles. We report the presence of P. elegans in a captive breeding colony of squirrel monkeys ( Saimiri sciureus) in Mexico, and we describe a successful treatment protocol. Treatment involved 2 steps: oral administration of the drugs loperamide chlorhydrate (0.5 mg/0.9 kg/3 days) and niclosamide (0.2 mg/0.9 kg/3 days) followed by surgical removal of adult worms from the intestine. Fecal examination during treatment revealed live adults but no living juveniles and no eggs. Surgery after 1 wk of treatment revealed the presence of adults and an absence of juvenile parasites. All adults were physically extracted during the surgery. All subjects recovered from surgery within 1 wk.


Assuntos
Acantocéfalos , Helmintíase Animal/terapia , Doenças dos Macacos/parasitologia , Doenças dos Macacos/terapia , Saimiri/parasitologia , Animais , Anti-Helmínticos/uso terapêutico , Baratas/parasitologia , Surtos de Doenças/veterinária , Quimioterapia Combinada/veterinária , Fezes/parasitologia , Comportamento Alimentar , Feminino , Helmintíase Animal/epidemiologia , Helmintíase Animal/parasitologia , Enteropatias Parasitárias/epidemiologia , Enteropatias Parasitárias/parasitologia , Enteropatias Parasitárias/terapia , Enteropatias Parasitárias/veterinária , Mucosa Intestinal/parasitologia , Mucosa Intestinal/cirurgia , Loperamida/uso terapêutico , Masculino , México/epidemiologia , Doenças dos Macacos/epidemiologia , Neópteros/parasitologia , Niclosamida/uso terapêutico
3.
Am J Epidemiol ; 170(10): 1207-21, 2009 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-19846566

RESUMO

Worldwide, over 1 million cases of colorectal cancer (CRC) were reported in 2002, with a 50% mortality rate, making CRC the second most common cancer in adults. Certain racial/ethnic populations continue to experience a disproportionate burden of CRC. A common polymorphism in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene has been associated with a lower risk of CRC. The authors performed both a meta-analysis (29 studies; 11,936 cases, 18,714 controls) and a pooled analysis (14 studies; 5,068 cases, 7,876 controls) of the C677T MTHFR polymorphism and CRC, with stratification by racial/ethnic population and behavioral risk factors. There were few studies on different racial/ethnic populations. The overall meta-analysis odds ratio for CRC for persons with the TT genotype was 0.83 (95% confidence interval (CI): 0.77, 0.90). An inverse association was observed in whites (odds ratio = 0.83, 95% CI: 0.74, 0.94) and Asians (odds ratio = 0.80, 95% CI: 0.67, 0.96) but not in Latinos or blacks. Similar results were observed for Asians, Latinos, and blacks in the pooled analysis. The inverse association between the MTHFR 677TT polymorphism and CRC was not significantly modified by smoking status or body mass index; however, it was present in regular alcohol users only. The MTHFR 677TT polymorphism seems to be associated with a reduced risk of CRC, but this may not hold true for all populations.


Assuntos
Neoplasias Colorretais/genética , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Polimorfismo de Nucleotídeo Único , Neoplasias Colorretais/enzimologia , Neoplasias Colorretais/epidemiologia , Intervalos de Confiança , Métodos Epidemiológicos , Frequência do Gene , Modelos Logísticos , Metilenotetra-Hidrofolato Redutase (NADPH2)/metabolismo , NADP/genética , NADP/metabolismo , Razão de Chances , Fatores de Risco , Estados Unidos/epidemiologia
5.
J Biol Chem ; 275(38): 29225-32, 2000 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-10871625

RESUMO

The sequences of nitric-oxide synthase flavin domains closely resemble that of NADPH-cytochrome P450 reductase (CPR). However, all nitric-oxide synthase (NOS) isoforms are 20-40 residues longer in the C terminus, forming a "tail" that is absent in CPR. To investigate its function, we removed the 33 and 42 residue C termini from neuronal NOS (nNOS) and endothelial NOS (eNOS), respectively. Both truncated enzymes exhibited cytochrome c reductase activities without calmodulin that were 7-21-fold higher than the nontruncated forms. With calmodulin, the truncated and wild-type enzymes reduced cytochrome c at approximately equal rates. Therefore, calmodulin functioned as a nonessential activator of the wild-type enzymes and a partial noncompetitive inhibitor of the truncated mutants. Truncated nNOS and eNOS plus calmodulin catalyzed NO formation at rates that were 45 and 33%, respectively, those of their intact forms. Without calmodulin, truncated nNOS and eNOS synthesized NO at rates 14 and 20%, respectively, those with calmodulin. By using stopped-flow spectrophotometry, we demonstrated that electron transfer into and between the two flavins is faster in the absence of the C terminus. Although both CPR and intact NOS can exist in a stable, one-electron-reduced semiquinone form, neither of the truncated enzymes do so. We propose negative modulation of FAD-FMN interaction by the C termini of both constitutive NOSs.


Assuntos
Calmodulina/metabolismo , Óxido Nítrico Sintase/química , Óxido Nítrico Sintase/metabolismo , Sequência de Aminoácidos , Animais , Calmodulina/química , Transporte de Elétrons , Escherichia coli , Flavinas/química , Flavinas/metabolismo , Heme/química , Heme/metabolismo , Dados de Sequência Molecular , Óxido Nítrico Sintase Tipo III , Ratos , Alinhamento de Sequência
7.
J Biol Chem ; 275(29): 21914-9, 2000 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-10781602

RESUMO

The sequences of nitric-oxide synthase (NOS) flavin domains closely resemble that of NADPH-cytochrome P450 reductase (CPR), with the exception of a few regions. One such region is the C terminus; all NOS isoforms are 20-40 amino acids longer than CPR, forming a "tail" that is absent in CPR. To investigate its function, we removed the 21-amino acid C-terminal tail from murine macrophage inducible NOS (iNOS) holoenzyme and from a flavin domain construct. Both the truncated holoenzyme and reductase domain exhibited cytochrome c reductase activities that were 7-10-fold higher than the nontruncated forms. The truncated holoenzyme catalyzed NO formation approximately 20% faster than the intact form. Using stopped-flow spectrophotometry, we demonstrated that electron transfer into and between the two flavins and from the flavin to the heme domain is 2-5-fold faster in the absence of the C-terminal tail. The heme-nitrosyl complex, formed in all NOS isoforms during NO catalysis, is 5-fold less stable in truncated iNOS. Although both CPR and intact NOS can exist in a stable, one electron-reduced semiquinone form, neither the truncated holoenzyme nor the truncated flavin domain demonstrate such a form. We propose that this C-terminal tail curls back to interact with the flavin domain in such a way as to modulate the interaction between the two flavin moieties.


Assuntos
Flavinas/química , Óxido Nítrico Sintase/química , Animais , Transporte de Elétrons , Escherichia coli , Flavinas/genética , Flavinas/metabolismo , Macrófagos , Camundongos , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico Sintase Tipo II , Oxirredução , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
18.
JEMS ; 20(8): 29, 1995 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10144796

RESUMO

What's red and white and huge all over? Monster ambulances built by Braun Northwest of Chehalis, Wash., for a Russian mining company.


Assuntos
Ambulâncias , Desenho de Equipamento , Oxigenoterapia Hiperbárica/instrumentação , Mineração , Comércio , Humanos , Sulfeto de Hidrogênio/intoxicação , Exposição Ocupacional , Federação Russa , Washington
19.
Am J Pathol ; 145(3): 585-97, 1994 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-8080041

RESUMO

Fibronectin (Fn) regulates cell migration, proliferation, and extracellular matrix formation during embryogenesis, angiogenesis, and wound healing. Fn also promotes mesangial cell migration and proliferation in vitro and contributes to extracellular matrix formation and tissue remodeling during glomerular disease. In this study, we examined, by immunohistochemistry and in situ hybridization, the temporal glomerular localization and cellular sources of Fn in Habu snake venom (HSV)-induced proliferative glomerulonephritis. Early HSV-induced glomerular lesions consisted of microaneurysms devoid of resident glomerular cells and filled with platelets, leukocytes, and erythrocytes. Over the course of the disease, mesangial cells migrated into the lesions, proliferated, and formed a confluent cellular mass. Fn was present in lesions beginning at 8 hours, with highest intensity at 72 hours and diminishing at 2 weeks after HSV. Staining for Fn at 8 and 24 hours after HSV was attributed to platelets and macrophages. In situ hybridization and phenotypic identification of cell types within lesions revealed macrophages as the predominant source of cellular Fn mRNA at these times. At 48 hours after HSV, Fn mRNA was expressed in proliferating mesangial cells in addition to macrophages. Most cells in lesions at 72 hours after HSV were mesangial, at a time when expression of Fn mRNA peaked. Cellular expression for Fn mRNA and translated protein declined at 2 weeks after HSV. These studies support the hypothesis that Fn, derived from platelets and macrophages, provides a provisional matrix involved with mesangial cell migration into glomerular lesions. Fn produced by mesangial cells might contribute to the formation of a stable extracellular matrix.


Assuntos
Plaquetas/metabolismo , Fibronectinas/metabolismo , Mesângio Glomerular/metabolismo , Glomerulonefrite Membranoproliferativa/metabolismo , Macrófagos/metabolismo , Animais , Divisão Celular , Movimento Celular , Modelos Animais de Doenças , Mesângio Glomerular/patologia , Glomerulonefrite Membranoproliferativa/etiologia , Glomerulonefrite Membranoproliferativa/patologia , Imuno-Histoquímica , Hibridização In Situ , Masculino , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA