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排序方式: 共有77条查询结果,搜索用时 15 毫秒
41.
Ponnappan RK Markova DZ Antonio PJ Murray HB Vaccaro AR Shapiro IM Anderson DG Albert TJ Risbud MV 《Arthritis research & therapy》2011,13(5):R171
Introduction
Back pain, a significant source of morbidity in our society, is related to the degenerative changes of the intervertebral disc. At present, the treatment of disc disease consists of therapies that are aimed at symptomatic relief. This shortcoming stems in large part from our lack of understanding of the biochemical and molecular events that drive the disease process. The goal of this study is to develop a model of early disc degeneration using an organ culture. This approach is based on our previous studies that indicate that organ culture closely models molecular events that occur in vivo in an ex vivo setting. 相似文献42.
43.
Hernández-Quintero JD MH Reyes-Valdés DV Mendoza-Rodríguez M Gómez-Martínez R Rodríguez-Herrera 《Phyton》2015,84(1):107-112
The genus Dasylirion is a group of plants typically present in the Chihuahuan Desert, perennial, with a dioecious sexual behavior and commonly called sotoles. This genus has been little studied from the biological point of view, and the bases of its reproductive response remain unknown. In this work we studied the chromosome number and meiotic response of Dasylirion cedrosanum in the county of Saltillo, Coahuila, located at the North East of Mexico. For the preparation of mitotic chromosomes, we used a technique based on enzymatic treatment with pectolyase and cellulase, as well as staining with acetocarmin dye. For the study of meiosis, male flower buds were collected, fixed and stained for analysis with the same dye. As a result, the gametic (n = x = 19) and somatic chromosome (2n = 38) numbers of D. cedrosanum are reported for the first time, being consistent with previous findings in other Dasylirion species, which points to a constant ploidy level across the genus. Variation was observed in the morphology and size of the somatic chromosomes, with types ranging from submetacentric to subtelocentric, and sizes oscillating in a range of 4.43 µm, with an average total length of 112.38 µm for the diploid chromosome complement. This shows that the chromosome complement of D. cedrosanom would belong to a 3B classification of Stebins, with a medium variation between chromosome lengths and low chromosome asymmetry. This variation indicates the feasibility of constructing a chromosome ideotype for this species. The meiotic chromosome pairing showed a chromosome behavior consistent with a disomic inheritance characteristic of a diploid species, with prevalence of ring and chain bivalents, typically without pairing abnormalities. Bivalent configurations in all cases were symmetrical.The normal and symmetrical meiotic pairing indicates a balanced production of gametes, and suggests the absence of heteromorphic sex determination. 相似文献
44.
Brass DM Savov JD Gavett SH Haykal-Coates N Schwartz DA 《American journal of physiology. Lung cellular and molecular physiology》2003,285(3):L755-L761
The endotoxin component of organic dusts causes acute reversible airflow obstruction and airway inflammation. To test the hypothesis that endotoxin alone causes airway remodeling, we have compared the response of two inbred mouse strains to subchronic endotoxin exposure. Physiological and biological parameters were evaluated after 1 day, 5 days, or 8 wk of exposure to endotoxin [lipopolysaccharide (LPS)] in endotoxin-sensitive (C3HeB/FeJ) and endotoxin-resistant (C3H/HeJ) mice. After 5 days or 8 wk of LPS exposure, only C3HeB/FeJ had elevated airway hyperreactivity to inhaled methacholine. Only the C3HeB/FeJ mice had significant inflammation of the lower respiratory tract after 1 day, 5 days, or 8 wk of LPS exposure. Stereological measurements of small, medium, and large airways indicated that an 8-wk exposure to LPS resulted in expansion of the submucosal area only in the C3HeB/FeJ mice. Cell proliferation as measured by bromodeoxyuridine incorporation contributed to the expansion of the submucosa and was only significantly elevated in C3HeB/FeJ mice actively exposed to LPS. C3HeB/FeJ mice had significantly elevated levels of interleukin-1beta protein in whole lung lavage after 1 day and 5 days of LPS exposure and significantly elevated protein levels of total and active transforming growth factor-beta1 in whole lung lavage fluid after 5 days of LPS exposure. Our findings demonstrate that subchronic inhalation of LPS results in the development of persistent airway disease in endotoxin-responsive mice. 相似文献
45.
Herbein JF Savov J Wright JR 《American journal of physiology. Lung cellular and molecular physiology》2000,278(4):L830-L839
Alveolar type II cells secrete, internalize, and recycle pulmonary surfactant, a lipid and protein complex that increases alveolar compliance and participates in pulmonary host defense. Surfactant protein (SP) D, a collagenous C-type lectin, has recently been described as a modulator of surfactant homeostasis. Mice lacking SP-D accumulate surfactant in their alveoli and type II cell lamellar bodies, organelles adapted for recycling and secretion of surfactant. The goal of current study was to characterize the interaction of SP-D with rat type II cells. Type II cells bound SP-D in a concentration-, time-, temperature-, and calcium-dependent manner. However, SP-D binding did not alter type II cell surfactant lipid uptake. Type II cells internalized SP-D into lamellar bodies and degraded a fraction of the SP-D pool. Our results also indicated that SP-D binding sites on type II cells may differ from those on alveolar macrophages. We conclude that, in vitro, type II cells bind and recycle SP-D to lamellar bodies, but SP-D may not directly modulate surfactant uptake by type II cells. 相似文献
46.
47.
Nonparametric regression in the presence of measurement error 总被引:4,自引:0,他引:4
48.
Rampant horizontal transfer and duplication of rubisco genes in eubacteria and plastids 总被引:14,自引:2,他引:14
Previous work has shown that molecular phylogenies of plastids,
cyanobacteria, and proteobacteria based on the rubisco (ribulose-1,5-
bisphosphate carboxylase/oxygenase) genes rbcL and rbcS are incongruent
with molecular phylogenies based on other genes and are also incompatible
with structural and biochemical information. Although it has been much
speculated that this is the consequence of a single horizontal gene
transfer (of a proteobacterial or mitochondrial rubisco operon into
plastids of rhodophytic and chromophytic algae), neither this hypothesis
nor the alternative hypothesis of ancient gene duplication have been
examined in detail. We have conducted phylogenetic analyses of all
available bacterial rbcL sequences, and representative plastid sequences,
in order to explore these alternative hypothesis and fully examine the
complexity of rubisco gene evolution. The rbcL phylogeny reveals a
surprising number of gene relationships that are fundamentally incongruent
with organismal relationships as inferred from multiple lines of other
molecular evidence. On the order of six horizontal gene transfers are
implied by the form I (L8S8) rbcL phylogeny, two between cyanobacteria and
proteobacteria, one between proteobacteria and plastids, and three within
proteobacteria. Alternatively, a single ancient duplication of the form I
rubisco operon, followed by repeated and pervasive differential loss of one
operon or the other, would account for much of this incongruity. In all
probability, the rubisco operon has undergone multiple events of both
horizontal gene transfer and gene duplication in different lineages.
相似文献
49.
Anna Kuyumdzhieva-Savova Valentin A. Savov Ljubka K. Genova Sofia P. Peikova 《FEMS microbiology letters》1985,27(1):103-105
Abstract Superoxide dismutase (SOD) activity of 4 strains of methylotrophic yeasts of the genera Candida, Torulopsis, Hansenula and Pichia was demonstrated. Strains tested were grown on glucose or methanol. Yeasts grown on methanol possessed considerably higher levels of SOD- and catalase activity than cells cultivated on glucose. 相似文献
50.