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Search Results: 1 - 10 of 339039 matches for " Diana Carolina Casta?eda Cortés "
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Estudio Morfométrico del Nervio óptico de Tiburoncito (Ariopsis seemanni) Morphological Study of Tete Sea Catfish (Ariopsis seemanni) Optic Nerve
Diana Carolina Castaeda Cortés,Oswaldo Tovar Bohórquez,Hernán Hurtado Giraldo
International Journal of Morphology , 2013,
Abstract: En peces, el nervio óptico es el encargado de transportar la información integrada por las células ganglionares de la retina hacia el tectum óptico, para que se generen imágenes acerca del entorno. El objetivo de este trabajo es describir morfométricamente el nervio óptico del tiburoncito (Ariopsis seemanni), para lo cual se utilizó la Microscopía óptica de Alta Resolución (MOAR), realizando cortes a 1 micra de espesor. El nervio óptico de A. seemanni presenta fibras mielínicas de diverso calibre, acompa adas de oligodendrocitos y astrocitos. El nervio está cubierto por las meninges, que presentan vasos sanguíneos y adipocitos. El nervio tiene un área total de 179604 ± 30163 μm2, diámetro de 478 ± 42 μm y un número total de fibras mielínicas de 22848 ± 4350, de las cuales la mayoría tiene un tama o peque o, que puede estar relacionado con una velocidad de conducción baja. The optic nerve carries out the information integrated by retinal ganglion cells towards the optic tectum, so that surrounding environment images are generated. The main goal of this paper is to describe morphometricaly the Tete sea catfish (Ariopsis seemanni) optic nerve, using high resolution optical microscopy (HROM), on 1 micron thick sections. A. seemanni optic nerve does present myelinated nerve fibers, accompanied by oligodendrocytes and astrocytes. The nerve is covered by the meninges, with blood vessels and adipocites. The nerve has a transversal area of 179,604 ± 30163 mm2, a diameter of 478 ± 42 mm and 22848 ± 4350 myelinated fibers, most are small in size, which may be related to a low conduction velocity.
Crossover of the Hypothalamic Pituitary–Adrenal/Interrenal, –Thyroid, and –Gonadal Axes in Testicular Development
Diana C. Castaeda Cortés,Valerie S. Langlois,Juan I. Fernandino
Frontiers in Endocrinology , 2014, DOI: 10.3389/fendo.2014.00139
Abstract: Besides the well-known function of thyroid hormones (THs) for regulating metabolism, it has recently been discovered that THs are also involved in testicular development in mammalian and non-mammalian species. THs, in combination with follicle stimulating hormone, lead to androgen synthesis in Danio rerio, which results in the onset of spermatogenesis in the testis, potentially relating the hypothalamic–pituitary–thyroid (HPT) gland to the hypothalamic–pituitary–gonadal (HPG) axes. Furthermore, studies in non-mammalian species have suggested that by stimulating the thyroid-stimulating hormone (TSH), THs can be induced by corticotropin-releasing hormone. This suggests that the hypothalamic–pituitary–adrenal/interrenal gland (HPA) axis might influence the HPT axis. Additionally, it was shown that hormones pertaining to both HPT and HPA could also influence the HPG endocrine axis. For example, high levels of androgens were observed in the testis in Odonthestes bonariensis during a period of stress-induced sex-determination, which suggests that stress hormones influence the gonadal fate toward masculinization. Thus, this review highlights the hormonal interactions observed between the HPT, HPA, and HPG axes using a comparative approach in order to better understand how these endocrine systems could interact with each other to influence the development of testes.
Laser assisted decay of quasistationary states
H. M. Castaeda Cortés,S. V. Popruzhenko,D. Bauer,A. Pálffy
Physics , 2011, DOI: 10.1088/1367-2630/13/6/063007
Abstract: The effects of intense electromagnetic fields on the decay of quasistationary states are investigated theoretically. We focus on the parameter regime of strong laser fields and nonlinear effects where an essentially nonperturbative description is required. Our approach is based on the imaginary time method previously introduced in the theory of strong-field ionization. Spectra and total decay rates are presented for a test case and the results are compared with exact numerical calculations. The potential of this method is confirmed by good quantitative agreement with the numerical results.
Tama?o gonadal de machos de Chaetodipus arenarius (Rodentia: Heteromyidae) durante un ciclo reproductivo en Baja California Sur, México
Cortés-Calva,Patricia; Alvarez-Castaeda,Sergio Ticul;
Revista de Biología Tropical , 1999,
Abstract: the description of reproductive activity in small nocturnal mammals is difficult. in this study we use the variation of testis characteristics over time. from february through december 1993 we set 1628 traps/night for the capture of specimens. we were studying the variation of testis size of 30 chaetodipus arenarius sublucidus, and analyzing the morphometric characteristics and morphology of the sperm of this species compared with c. spinatus. we recorded the abundance of sperm per age. the size of the testis was greater from february through september, during which there was reproduction activity, and this corresponds to a larger amount of sperm. there were morphometric differences in the length size of sperm. the gonadal-somatic index indirectly indicated the reproductive activity.
Rodent density anomalies in scrub vegetation areas as a response to ENSO 1997-98 in Baja California Sur, Mexico
Patricia Cortés-Calva,Sergio Ticul álvarez-Castaeda
Geofísica internacional , 2003,
Abstract: ENSO significantly changed the annual patterns of rainfall and temperature for northwestern Mexico. Little is known about how seasonal environmental differences influence the long-term pattern of distribution and density of rodents in desert habitats of North America. We report data from a long-term study (October 1994-December 1999) of two areas west of La Paz, Baja California Sur, Mexico. One is a natural preserve and the other is grazing land. Both have the same original vegetation, soil, and weather. Densities of rodent populations in both areas were compared. El Ni o’s impact in La Paz region did not increase rainfall, as in other areas of Mexico. In the grazing area, monthly anomalies of rodent density showed a significant impact from the ENSO event, but the preserve showed less impact. Rodent population variations can be related to the precipitation effect. In the grazing area, the effect is much stronger. During the rainy season, population increases, but in the dry period, the population strongly declines. The effect lasts many months, and is related to the reduced number of perennial species. For altered desert areas, the dry season of ENSO was the most significance part of the event.
Tama o gonadal de machos de Chaetodipus arenarius (Rodentia: Heteromyidae) durante un ciclo reproductivo en Baja California Sur, México
Patricia Cortés-Calva,Sergio Ticul Alvarez-Castaeda
Revista de Biología Tropical , 1999,
Abstract: El patrón de reproducción de roedores nocturnos es difícil de describirse en condiciones naturales, para inferirse se recurrió a las características de la gónada a través del tiempo. De Febrero a Septiembre de 1993, colocándose 1628 trampas/noche para la captura de roedores. Se estudió la variación del tama o testicular de machos de Chaetodipus arenarius sublucidus, además se analizó la morfometría y morfología de espermatozoides de 30 C. arenarius comparándose con la de 30 C. spinatus. Al mismo tiempo se registró la abundancia por clases de edad. El tama o de los testículos fue mayor de febrero a septiembre, época en la que ocurre la actividad reproductora, y que se relacionó con una mayor cantidad de espermatozoides. Existió diferencia morfométrica de los espermatozoides de las dos especies. Los índices gonadosomáticos advierten indirectamente la actividad reproductora. The description of reproductive activity in small nocturnal mammals is difficult. In this study we use the variation of testis characteristics over time. From February through December 1993 we set 1628 traps/night for the capture of specimens. We were studying the variation of testis size of 30 Chaetodipus arenarius sublucidus, and analyzing the morphometric characteristics and morphology of the sperm of this species compared with C. spinatus. We recorded the abundance of sperm per age. The size of the testis was greater from February through September, during which there was reproduction activity, and this corresponds to a larger amount of sperm. There were morphometric differences in the length size of sperm. The gonadal-somatic index indirectly indicated the reproductive activity.
Nuclear recollisions in laser-assisted $α$ decay
Héctor Mauricio Castaeda Cortés,Carsten Müller,Christoph H. Keitel,Adriana Pálffy
Physics , 2012, DOI: 10.1016/j.physletb.2013.05.025
Abstract: Laser-induced nuclear recollisions following $\alpha$ decay in the presence of an intense laser field are investigated theoretically. We show that while an intense optical laser does not influence notably the tunneling rate in $\alpha$ decay, it can completely change the $\alpha$ particle spectrum. For intensities of $10^{22}-10^{23}$ W/cm$^{2}$, the field is strong enough to induce recollisions between the emitted $\alpha$ particle and the daughter nucleus. The energy gained by the $\alpha$ particle in the field can reach 20 MeV and suffice to trigger several types of nuclear reactions on a femtosecond time scale. Similar conclusions can be drawn about laser-induced recollisions after proton emission. Prospects for the experimental realization of laser-induced nuclear recollisions are discussed.
Evaluación citológica y microbiológica de lavados uterinos en bovinos con problemas reproductivos (estudio preliminar)
Milena Sánchez L.,Carolina González C.,Rubiela Castaeda S.,Adriana Pulido V.
Revista MVZ Córdoba , 2011,
Abstract: Objetivo. Determinar las características citológicas y microbiológicas de lavados uterinos de bajo volúmen en hembras con problemas reproductivos en dos hatos del Altiplano Cundiboyacense. Materiales y métodos. Se evaluaron 21 muestras de lavados uterinosde vacas con historia de problemas reproductivos procedentes de dos hatos lecheros, en el primer hato ubicado en Sibaté (Cundinamarca) se muestrearon 10 animales y en el segundo ubicado en Ventaquemada (Boyacá) se obtuvieron las 11 muestras restantes. Se realizó evaluación macroscópica y microscópica de cada uno de los lavados uterinos; para la evaluación citológica se utilizaron las tinciones de Gram y Wright. La determinación de la flora bacteriana se realizó mediante técnicas estándar en microbiología para la identificaciónde bacterias no exigentes, adicionalmente se realizaron pruebas de sensibilidad por la técnica de difusión de Kirby-bauer. Resultados. En la citología se observaron bacilos y cocos gram positivos, células epiteliales de descamación uterina (CEDU) y respuesta inflamatoria (RI) mediada por polimorfonucleares (PMN). Los aislamientos bacterianos correspondieron a Lactobacillus sp como flora bacteriana normal del tracto genital (16.66%) y Klebsiella sp como flora acompa ante (16.66%); adicionalmente se aislaron bacterias patógenas causantes de problemas reproductivos como Streptococcus sp. β hemolítico (33.33%), Streptococcus sp α hemolítico (50%) y Streptococcus sp. γ hemolítico (50%) y Arcanobacterium pyogenes (Corynebacterium-Actinomyces pyogenes) (16.66%); en un 9.52% de las muestras se observaron espiroquetas. Conclusiones. Se observó una relación directa entre el aspecto macroscópico de los lavados uterinos, la respuesta citológica y el aislamiento de bacterias.
Incremento de la resistencia a eritromicina de Streptococcus pneumoniae, Colombia, 1994-2008
Hidalgo,Marylin; Santos,Claudia; Duarte,Carolina; Castaeda,Elizabeth; Agudelo,Clara Inés;
Biomédica , 2011,
Abstract: introduction. streptococcus pneumoniae is a commonly implicated agent in invasive disease. for infections of s. pneumoniae resistant to b-lactam, macrolides are an alternative treatment. however, resistance to macrolides has increased worldwide as well. objective. the frequency of resistance to erythromycin was determined for s. pneumoniae over a 15-year surveillance period, and the resistant isolates were characterized phenotypically and genotypically. materials and methods. demographic data of the patients, antimicrobial susceptibility and serotypes were analyzed for 3,241 s. pneumoniae isolates recovered between 1994 and 2008. the phenotypes were determined by the double-disc technique and genotypes by pcr (polymerase chain reaction) and pfge (pulsed field gel electrophoresis). isolates were recovered from invasive diseases and were provided by national public health laboratories. results. of the 3,241 isolates, 136 were resistant to erythromycin. in the 12-year period between 1994-1996 and 2006-2008, resistance in each 2-year sampling had increased from 2.4% to 6.9% in children under 6 years and from 3.3% to 5.7% in adults. the most common serotypes were 6b (36.8%), 14 (16.9%) and 6a (17.6%). constitutive phenotype cmlsb was determined in 87 isolates; 82 of these expressed the ermb gene. phenotype m was determined in 46 isolates; 45 had the mefa gene. an additional three isolates expressed the inducible phenotype (imlsb), and one expressed the ermb gene. by pfge, 50 of the isolates were found to be related to international clones--58% were spain6b-st90, 26% spain9v-st156, 8% colombia23f-st338 and 8% spain23f-st81. conclusion. the increase in erythromycin resistance was primarily related to the mechanism of ribosomal methylation. more than half the cases were congeneric with the clone spain6b-st90 that has been circulating in colombia since 1994.
Retrospective Study of the Epidemiology and Clinical Manifestations of Cryptococcus gattii Infections in Colombia from 1997–2011
Jairo Lizarazo,Patricia Escandón,Clara Inés Agudelo,Carolina Firacative,Wieland Meyer,Elizabeth Castaeda
PLOS Neglected Tropical Diseases , 2014, DOI: 10.1371/journal.pntd.0003272
Abstract: Background Cryptococcosis due to Cryptococcus gattii is endemic in various parts of the world, affecting mostly immunocompetent patients. A national surveillance study of cryptococcosis, including demographical, clinical and microbiological data, has been ongoing since 1997 in Colombia, to provide insights into the epidemiology of this mycosis. Methodology/Principal Findings From 1,209 surveys analyzed between 1997–2011, 45 cases caused by C. gattii were reported (prevalence 3.7%; annual incidence 0.07 cases/million inhabitants/year). Norte de Santander had the highest incidence (0.81 cases/million/year), representing 33.3% of all cases. The male: female ratio was 3.3:1. Mean age at diagnosis was 41±16 years. No specific risk factors were identified in 91.1% of patients. HIV infection was reported in 6.7% of patients, autoimmune disease and steroids use in 2.2%. Clinical features included headache (80.5%), nausea/vomiting (56.1%) and neurological derangements (48.8%). Chest radiographs were taken in 21 (46.7%) cases, with abnormal findings in 7 (33.3%). Cranial CT scans were obtained in 15 (33.3%) cases, with abnormalities detected in 10 (66.7%). Treatment was well documented in 30 cases, with most receiving amphotericin B. Direct sample examination was positive in 97.7% cases. Antigen detection was positive for all CSF specimens and for 75% of serum samples. C. gattii was recovered from CSF (93.3%) and respiratory specimens (6.6%). Serotype was determined in 42 isolates; 36 isolates were serotype B (85.7%), while 6 were C (14.3%). The breakdowns of molecular types were VGII (55.6%), VGIII (31.1%) and VGI (13.3%). Among 44 strains, 16 MLST sequence types (ST) were identified, 11 of them newly reported. Conclusions/Significance The results of this passive surveillance study demonstrate that cryptococcosis caused by C. gattii has a low prevalence in Colombia, with the exception of Norte de Santander. The predominance of molecular type VGII is of concern considering its association with high virulence and the potential to evolve into outbreaks.
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