Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
1.
Entropy (Basel) ; 22(9)2020 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-33286796

RESUMO

Chaotic dynamical systems are studied in this paper. In the models, integer order time derivatives are replaced with the Caputo fractional order counterparts. A Chebyshev spectral method is presented for the numerical approximation. In each of the systems considered, linear stability analysis is established. A range of chaotic behaviours are obtained at the instances of fractional power which show the evolution of the species in time and space.

2.
Anim Genet ; 48(4): 412-419, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28224649

RESUMO

Chromosomal abnormalities in the sex chromosome pair (ECAX and ECAY) are widely associated with reproductive problems in horses. However, a large proportion of these abnormalities remains undiagnosed due to the lack of an affordable diagnostic tool that allows for avoiding karyotyping tests. Hereby, we developed an STR (single-tandem-repeat)-based molecular method to determine the presence of the main sex chromosomal abnormalities in horses in a fast, cheap and reliable way. The frequency of five ECAX-linked (LEX026, LEX003, TKY38, TKY270 and UCDEQ502) and two ECAY-linked (EcaYH12 and SRY) markers was characterized in 261 Purebred Spanish Horses to determine the efficiency of the methodology developed to be used as a chromosomal diagnostic tool. All the microsatellites analyzed were highly polymorphic, with a sizeable number of alleles (polymorphic information content > 0.5). Based on this variability, the methodology showed 100% sensitivity and 99.82% specificity to detect the most important sex chromosomal abnormalities reported in horses (chimerism, Turner's syndrome and sex reversal syndromes). The method was also validated with 100% efficiency in 10 individuals previously diagnosed as chromosomally aberrant. This STR screening panel is an efficient and reliable molecular-cytogenetic tool for the early detection of sex chromosomal abnormalities in equines that could be included in breeding programs to save money, effort and time of veterinary practitioners and breeders.


Assuntos
Testes Genéticos/veterinária , Doenças dos Cavalos/genética , Cavalos/genética , Infertilidade/genética , Aberrações dos Cromossomos Sexuais , Animais , Cruzamento , Feminino , Cariotipagem , Masculino , Repetições de Microssatélites , Espanha
3.
Reprod Domest Anim ; 52(2): 227-234, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27905141

RESUMO

Chromosomal abnormalities are one of the main causes of genetic infertility in horses. Currently, their detection rate is rising due to the use of new diagnostic tools employing molecular markers linked to the sex chromosome pair. Despite genetic similarities, there are no previous reports of sterility associated with chromosomal abnormalities in the domestic donkey (Equus asinus). Hereby, we determined the presence of a chromosomal mosaicism in a female donkey with reproductive problems using molecular methodologies developed for horses. A two-and-a-half-year-old jenny characterized by morphological abnormalities of the reproductive tract was cytogenetically analysed using conventional and fluorescent techniques and a group of microsatellite markers (short tandem repeat, STR). At the same time, five ultrasound measures of the reproductive tract were taken and compared with eight contemporary jennies of the same breed. After slaughter, morphological examinations showed that the case study had a blind vaginal vestibule defining an empty pouch that covered the entrance of the cervical os. Histopathological studies demonstrated that this abnormal structure was compatible with a remnant hymen. Molecular markers, STR and fluorescent in situ hybridization determinations revealed that the animal was a 62, XX/61,X mosaic and, therefore, the first case of chromosomal abnormalities in the sex pair reported in donkeys.


Assuntos
Equidae/genética , Infertilidade Feminina/genética , Aberrações dos Cromossomos Sexuais/veterinária , Animais , Feminino , Repetições de Microssatélites
4.
J Anim Breed Genet ; 133(5): 347-56, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26991374

RESUMO

The association of five candidate genes with sporting performance in young and adult Spanish Trotter horses (STHs) was performed according to a previous selection based on quantitative analysis of the trait time per kilometre (TPK). A total of 334 516 records of TPK from 5958 STHs were used to estimate the estimated breeding values (EBVs) at different age groups (young and adults horses) throughout the range of distances (1600-2700 m) using a bicharacter random regression model. The heritability estimated by distance ranged from 0.16 to 0.40, with a different range for the two age groups. Considering the animals with the best and the worst deregressed EBV, 321 STHs were selected for SNP genotyping in MSTN, COX4I2, PDK4, DMRT3 and CKM genes. An association analysis based on ridge and logistic regression revealed that the young trotters with genotype GG in PDK4 (p < 0.05) and AA of DMRT3 (p < 0.001) SNPs show the best potential in short-distance races, while those carrying the genotype AA in DMRT3 (p < 0.001) and CC in CKM (p < 0.05) genes seem to be the best in long-distance races. Adult trotters with genotype AA in DMRT3 also display greater speed (p < 0.05) and endurance (p < 0.001).


Assuntos
Cavalos/genética , Animais , Cruzamento , Feminino , Estudos de Associação Genética , Cavalos/classificação , Cavalos/fisiologia , Masculino , Condicionamento Físico Animal , Polimorfismo de Nucleotídeo Único
5.
Cytogenet Genome Res ; 141(4): 277-83, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23735586

RESUMO

Chromosomal abnormalities associated to sex chromosomes are reported as a problem more common than believed to be in horses. Most of them remain undiagnosed due to the complexity of the horse karyotype and the lack of interest of breeders and veterinarians in this type of diagnosis. Approximately 10 years ago, the Spanish Purebred Breeders Association implemented a DNA paternity test to evaluate the pedigree of every newborn foal. All candidates who showed abnormal or uncertain results are routinely submitted to cytogenetical analysis to evaluate the presence of chromosomal abnormalities. We studied the case of a foal showing 3 and even 4 different alleles in several loci in the short tandem repeat (STR) -based DNA parentage test. To confirm these results, a filiation test was repeated using follicular hair DNA showing normal results. A complete set of conventional and molecular cytogenetic analysis was performed to determine their chromosomal complements. C-banding and FISH had shown that the foal presents a sex chimerism 64,XX/64,XY with a cellular percentage of approximately 70/30, diagnosed in blood samples. The use of a diagnostic approach combining routine parentage QF-PCR-based STR screening tested with classical or molecular cytogenetic analysis could be a powerful tool that allows early detection of foals that will have a poor or even no reproductive performance due to chromosomal abnormalities, saving time, efforts and breeders' resources.


Assuntos
Quimerismo/veterinária , Cavalos/genética , Aberrações dos Cromossomos Sexuais/veterinária , Alelos , Animais , Transtornos Cromossômicos/diagnóstico , Transtornos Cromossômicos/veterinária , Citogenética/métodos , Hibridização In Situ/veterinária , Cariótipo , Repetições de Microssatélites
6.
Res Vet Sci ; 141: 190-194, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34763255

RESUMO

Footrot is a contagious disease that affects the hoof of sheep and other ungulates. The severity of the disease varies from a slight limp to the death of the individual due to injuries that prevent them from feeding. Variants of the Major Histocompatibility Complex (MHC)-DQA2 gene (MHC-DQA2) have been associated with a greater or lesser susceptibility to footrot in Greek, New Zealand and German sheep. In this study, variation in ovine MHC-DQA2, the absence or presence of footrot and the severity of infection was analysed in 117 Spanish Merino, Black Merino and Churra Lebrijana sheep. A total of 21 alleles/haplotypes and 65 genotypes were found with different frequencies in these breeds. As found in other studies, the MHC-DQA2 allele *1101 appeared to be associated with increased susceptibility to footrot, while allele *1201 appeared to be associated with decreased susceptibility. Overall this would suggest the ovine MHC plays a role in controlling susceptibility to footrot infection and that there are breed differences in susceptibility. Sheep might therefore be able to be selected by their MHC-DQA2 alleles/haplotypes to reduce the incidence of the disease in flocks.


Assuntos
Pododermatite Necrótica dos Ovinos/genética , Complexo Principal de Histocompatibilidade , Doenças dos Ovinos , Carneiro Doméstico , Alelos , Animais , Predisposição Genética para Doença , Genótipo , Haplótipos , Ovinos , Doenças dos Ovinos/genética , Carneiro Doméstico/genética , Espanha
7.
Vet J ; 234: 142-144, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29680387

RESUMO

Twin foaling is associated with chimaerism in several domestic species and is recognised in horses. In this study, 21,097 purebred Spanish (Pura Raza Español) horse births from the 2015 to 2016 breeding season were investigated for chimaerism. Twin foaled and chimaeric individuals were assessed on the basis of foaling records, short-tandem repeat (STR) parentage test results and a sex-linked STR-based technique. Fourteen twin pregnancies with 23 twin foals born alive were identified (0.066% twin foaling prevalence), including five blood chimaeric cases (21.7%; overall prevalence 0.011%), suggesting that this genetic condition is extremely low in horses. Furthermore, no true chimaeras were detected. This is the first large scale study analysing the occurrence of chimaerism in a horse population and the first assessment of twin foaling in purebred Spanish horses.


Assuntos
Cruzamento , Quimera/genética , Desenvolvimento Embrionário/genética , Doenças dos Cavalos/epidemiologia , Animais , Quimera/crescimento & desenvolvimento , Cavalos , Repetições de Microssatélites , Prevalência
8.
Chaos ; 6(3): 493-503, 1996 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12780279

RESUMO

A method to identify the invariant subsets of bi-infinite configurations of cellular automata that propagate rigidly with a constant velocity nu is described. Causal traveling configurations, propagating at speeds not greater than the automaton range, mid R:numid R:

9.
Theriogenology ; 81(8): 1116-22, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24612694

RESUMO

Sex chromosome aberrations are known to cause congenital abnormalities and unexplained infertility in horses. Most of these anomalies remain undiagnosed because of the complexity of the horse karyotype and the lack of specialized laboratories that can perform such diagnoses. On the other hand, the utilization of microsatellite markers is a technique widely spread in horse breeding, mostly because of their usage in parentage tests. We studied the usage of a novel combination of diagnostic approaches in the evaluation of a very uncommon case of chromosomal abnormalities in a Spanish purebred colt, primarily detected using a commercial panel of short tandem repeat (STR) makers. Based on these results, we performed a full cytogenetic analysis using conventional and fluorescent in situ hybridization techniques with individual Equus caballus chromosome X and Equus caballus chromosome Y painting probes. We also tested the presence of two genes associated with the sexual development in horses and an extra novel panel of eight microsatellite markers specifically located in the sex chromosome pair. This is the first case report of a leukocyte chimerism between chromosomally normal (64,XY) and abnormal (63,X0) cell lines in horses. Our results indicate that the use of the short tandem repeat markers as a screening technique and as a confirmation utilizing cytogenetic techniques can be used as a very interesting, easy, and nonexpensive diagnostic approach to detect chromosomal abnormalities in the domestic horse.


Assuntos
Quimerismo , Doenças dos Cavalos/genética , Cavalos/genética , Aberrações dos Cromossomos Sexuais/veterinária , Animais , DNA/análise , DNA/sangue , Cabelo/química , Hibridização In Situ/veterinária , Hibridização in Situ Fluorescente/veterinária , Cariótipo , Cariotipagem/veterinária , Leucócitos/ultraestrutura , Repetições de Microssatélites/genética , Espanha , Cromossomo X/genética , Cromossomo Y/genética
10.
Histol Histopathol ; 29(6): 785-95, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24371036

RESUMO

Aging is a multifactorial universal process and constitutes the most important risk factor for chronic-degenerative diseases. Although it is a natural process, pathological aging arises when these changes occur quickly and the body is not able to adapt. This is often associated with the generation of reactive oxygen species (ROS), inflammation, and a decrease in the endogenous antioxidant systems, constituting a physiopathological state commonly found in chronic-degenerative diseases. At the testicular level, aging is associated with tissue atrophy, decreased steroidogenesis and spermatogenesis, and sexual behavior disorders. This situation, in addition to the elevated generation of ROS in the testicular steroidogenesis, provides a critical cellular environment causing oxidative damage at diverse cellular levels. To assess the effects of a reduction in the levels of ROS, thiamine pyrophosphate (TPP) was chronically administered in senile Wistar rats. TPP causes an activation of intermediate metabolism routes, enhancing cellular respiration and decreasing the generation of ROS. Our results show an overall decrease of atrophic histological changes linked to aging, with higher levels of serum testosterone, sexual activity, and an increase in the levels of endogenous antioxidant enzymes in TPP-treated animals. These results suggest that TPP chronic administration decreases the progression of age-related atrophic changes by improving the intermediate metabolism, and by increasing the levels of antioxidant enzymes.


Assuntos
Envelhecimento/patologia , Comportamento Sexual Animal/efeitos dos fármacos , Testículo/efeitos dos fármacos , Tiamina Pirofosfato/administração & dosagem , Complexo Vitamínico B/administração & dosagem , Envelhecimento/fisiologia , Animais , Atrofia/patologia , Masculino , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio , Comportamento Sexual Animal/fisiologia , Testículo/patologia , Testosterona/sangue
12.
Philos Trans A Math Phys Eng Sci ; 367(1901): 3173-81, 2009 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-19620116

RESUMO

We present a nonlinear model that allows exploration of the relationship between energy relaxation, thermal conductivity and the excess of low-frequency vibrational modes (LFVMs) that are present in glasses. The model is a chain of the Fermi-Pasta-Ulam (FPU) type, with nonlinear second neighbour springs added at random. We show that the time for relaxation is increased as LFVMs are removed, while the thermal conductivity diminishes. These results are important in order to understand the role of the cooling speed and thermal conductivity during glass transition. Also, the model provides evidence for the fundamental importance of LFVMs in the FPU problem.

13.
Artigo em Inglês | MEDLINE | ID: mdl-11709633

RESUMO

This study examines the influence of several college factors and learning activities on student learning as measured by performance on a standardized test. The study uses a national sample of 495 students who completed the Medical College Admission Test (MCAT) four years after entering college in the United States in 1989. Multiple regression analysis is used to examine the impact of between- and within-institution learning environments, and non-academic activities on student learning. The relative influence of between-institution characteristics is reported to be greater than that of within-institution factors. For example, the standardized coefficients for attending a university (public or private) are 0.15, and for the variables "physical science major" and "worked on a professor's research project" they are 0.08 and 0.07 respectively. The institutional type of college attended as an undergraduate, university as compared with 4-yr colleges, as well as opportunities to interact with faculty outside the classroom are positively associated with student performance.


Assuntos
Teste de Admissão Acadêmica/estatística & dados numéricos , Educação Médica , Aprendizagem , Estudantes de Medicina , Currículo , Etnicidade , Feminino , Humanos , Masculino , Análise de Regressão , Estados Unidos
14.
Am J Obstet Gynecol ; 170(3): 737-9, 1994 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8141192

RESUMO

We evaluated the feasibility of transvaginal methotrexate injection of viable cervical pregnancies to avoid complications of the "classic" surgical procedures in use and to preserve future fertility. Five viable cervical pregnancies, at 6 to 8 weeks, were treated. In three patients a spring-loaded automated puncture device and in two a manually operated simple needle guide mated to and guided by a transvaginal ultrasonography probe were used with 21-gauge needles. The puncture and injection treatment was successful and without complications in all five cases presented. This procedure may become a useful alternative to other, more radical or complex surgical approaches.


Assuntos
Colo do Útero/diagnóstico por imagem , Metotrexato/administração & dosagem , Gravidez Ectópica/tratamento farmacológico , Feminino , Humanos , Metotrexato/uso terapêutico , Gravidez , Gravidez Ectópica/diagnóstico por imagem , Punções , Ultrassonografia , Vagina
15.
Arch. venez. farmacol. ter ; 23(2): 118-121, 2004.
Artigo em Espanhol | LILACS | ID: lil-419062

RESUMO

El estado dippers es un factor de riesgo independiente en los pacientes hipertensos (Risers-R-) Non-dippers-ND-> Dippers-D>Dippers extremos-DE). Se evaluó el efecto de la nueva nifedipina en microgránulos (NMG) una vez al día en la disminución de la presión arterial nocturna medida a través del MAPA con Mobil-o-Graph-CE0434-(I.E.MGmbh-Cockerillstr. 69 D-Stolberg. Germany). Se incluyeron pacientes hipertensos (PAS mayor igual 140 y/o PAD mayor igual 90 mmHg, medidas con esfigmomanómetro de Hg) que recibieron de 30 a 60 mgrs/día de NMG, en un estudio prospectivo abierto comparativo y cruzado en time-doses 8 am ó 8 pm; que luego de 6 semanas de tratamiento mantuvieran PAS < 140 mmHg. Se reclutaron 73 pacientes. 40 pacientes (54.8 por ciento), mantuvieron su estado: NDn = 22 (disminución de la PAS nocturna entre 0 y 10 por ciento), D n= 16 (disminución de PAS nocturna entre 10 y 20 por ciento) y Rn = 2 (incremento de la PAS nocturna). Los otros 33 pacientes (45.2 por ciento) modificaron su estado: cinco: 3D y 2ND cambiaron a DE (disminución de la PAS nocturna > 20 por ciento), once: 2DE y 9ND se transformaron en D, catorce: 6R, 1DE y 7D hacia ND y 3D cambiaron a R. No hubo diferencias significativas en el cambio de estado dippers en ambos grupos (30 ó 60 mgrs), 17 pacientes mejoraron su estado (9ND y 2DE) se transformaron en D y 6R pasaron a ND; 16 pacientes dipper se mantuvieron. Estos resultados sugieren que la NMG ofrece en el 45 por ciento de los pacientes estudiados un beneficio independiente de la reducción de la presión arterial, manteniendo o mejorando el estado dippers ofreciendo una mejor predicción en la disminución de eventos cardiovasculares y del pronóstico de los accidentes cerebrovasculares


Assuntos
Humanos , Masculino , Feminino , Hipertensão/complicações , Hipertensão/terapia , Nifedipino , Pressão Sanguínea , Farmacologia , Terapêutica , Venezuela
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA