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排序方式: 共有244条查询结果,搜索用时 390 毫秒
91.
Guillermina Massaccesi Fidel A. Roig Guillermo J. Martínez Pastur Marcelo D. Barrera 《Trees - Structure and Function》2008,22(2):245-255
The influence of ecological factors resulting from altitude on growth characteristics of Nothofagus pumilio was analyzed. N. pumilio forests grow in the southern Andes from near sea level to 600 m.a.s.l. Eight study sites were selected in the southwestern
area of Tierra del Fuego, on north- and south-facing slopes, and distributed along an altitudinal gradient (200–600 m.a.s.l.).
Growth cycles throughout time were identified. The correlation between climate and tree growth was determined. Tree diameter
and height decreased whereas stand density increased towards tree-line. South-facing slopes showed higher values in common
growth variability, probably because of stronger climatic controlling factors. Climate-growth correlation models revealed
long-term temperature influences on growth variability, and showed variations among the different plots. Differences were
detected in the spectral power component of the chronologies throughout the altitudinal profile. The series had a significant
spectral peak at frequencies around 7 years, possibly related to mast seeding cycles. This signal became weaker as the altitude
increased probably due to lower seed production. These results suggest a strong altitudinal component in growth variability
of N. pumilio in Tierra del Fuego. 相似文献
92.
Mar Ruperto Guillermina Barril Francisco J Sánchez-Muniz 《Journal of physiology and biochemistry》2017,73(1):67-75
Abdominal fat has been recognized as the most hormonally active tissue secreting a variety of adipocytokines and, therefore, potentially contributing to inflammation. The conicity index (Cindex) has been considered a valuable indicator of central obesity. This study aims to relate plasma concentrations of leptin, adiponectin, interleukin-6 (IL-6), and serum C-reactive protein (CRP) with Cindex values in hemodialysis (HD) patients. Cross-sectional study in 45 HD patients (55.6 % men; DM 20 %; mean age, 68.1 year). Cindex and nutritional-inflammatory markers were used for the abdominal fat depot assessment. Patients were classified as having a low or high median Cindex (MCindex): low group (men, <1.39; women, <1.33) and high group (men, ≥1.39; women, ≥1.33). A combination of plasma leptin, IL-6, adiponectin, and CRP was used to design an inflammatory index (Iindex) while a protein-energy wasting index (PEWindex) was calculated from the Iindex plus the malnutrition-inflammation score (MIS). Waist circumference (WC) and Cindex but not BMI were significantly higher in men than in women (p < 0.01). The MCindex was significantly associated with the adipocytokine profile (CRP, leptin, and adiponectin). Patients with a high MCindex had a higher Iindex and PEWindex (p < 0.01). ROC curve analyses measured by area under the curve (AUC) were 0.69 and 0.68 (p < 0.05), for the Cindex and MCindex, respectively, demonstrating the usefulness of the Cindex as an abdominal fat mass biomarker able for wasting-inflamed HD patients. These findings in HD patients underscore the importance of incorporating the evaluation of one abdominal fat indicator, such as the Cindex and an inflammatory biomarker such as the IL-6 and CRP, in substitution of the BMI, in current clinical practice. 相似文献
93.
Fernando Alvarez Guillermina AlcarazRafael Robles 《Journal of experimental marine biology and ecology》2002,278(2):135-140
The osmoregulatory response of the blue crab Callinectes rathbunae parasitized with the rhizocephalan barnacle Loxothylacus texanus, and subjected to sudden salinity changes, was experimentally measured in the laboratory. Parasitized and control crabs were exposed to salinity changes every 3 h and their hemolymph osmolality measured. Two experiments, one with increasing salinity conditions (5‰, 12‰, 19‰, 25‰) and a second one with decreasing salinities (35‰, 25‰, 15‰, 5‰) were conducted. The results show that L. texanus significantly alters the hemolymph osmolality of C. rathbunae maintaining it at lower than normal levels. In the increasing salinity trial, the hypoosmotic hemolymph condition of parasitized crabs was present at all salinities tested, whereas in the decreasing salinity trial a significant effect was found only at salinities of 5‰ and 15‰. Since C. rathbunae is constantly subjected to abrupt salinity changes in the tropical estuaries where it occurs, moving into high salinity areas may be the only way to cope with the impact of L. texanus. 相似文献
94.
Khady Mayebine Sall Maria Guillermina Casabona Christophe Bordi Philippe Huber Sophie de Bentzmann Ina Attrée Sylvie Elsen 《PloS one》2014,9(4)
Pseudomonas aeruginosa, a human opportunistic pathogen, is capable of provoking acute and chronic infections that are associated with defined sets of virulence factors. During chronic infections, the bacterium accumulates mutations that silence some and activate other genes. Here we show that the cystic fibrosis isolate CHA exhibits a unique virulence phenotype featuring a mucoid morphology, an active Type III Secretion System (T3SS, hallmark of acute infections), and no Type VI Secretion System (H1-T6SS). This virulence profile is due to a 426 bp deletion in the 3′ end of the gacS gene encoding an essential regulatory protein. The absence of GacS disturbs the Gac/Rsm pathway leading to depletion of the small regulatory RNAs RsmY/RsmZ and, in consequence, to expression of T3SS, while switching off the expression of H1-T6SS and Pel polysaccharides. The CHA isolate also exhibits full ability to swim and twitch, due to active flagellum and Type IVa pili. Thus, unlike the classical scheme of balance between virulence factors, clinical strains may adapt to a local niche by expressing both alginate exopolysaccharide, a hallmark of membrane stress that protects from antibiotic action, host defences and phagocytosis, and efficient T3S machinery that is considered as an aggressive virulence factor. 相似文献
95.
Marta E. Hallak Guillermina Bongiovanni Héctor S. Barra 《Journal of neurochemistry》1991,57(5):1735-1739
The posttranslational incorporation of arginine into proteins catalyzed by arginyl-tRNA protein transferase was determined in vitro in different rat brain regions. The incorporation was found in all the regions studied, although with different specific activities (pmol [14C]arginine incorporated/mg protein). Of the regions studied, hippocampus had the highest specific activity followed by striatum, medulla oblongata, cerebellum, and cerebral cortex. Electrophoretic analysis of the [14C]arginyl proteins from the different regions followed by autoradiography and scanner densitometry showed at least 13 polypeptide bands that were labeled with [14C]arginine. The radioactive bands were qualitatively coincident with protein bands revealed by Coomassie Blue. There were peaks that showed different proportions of labeling in comparison with peaks of similar molecular mass from total brain. Most notable because of their high proportions were those of molecular mass 125 kDa in hippocampus, striatum, and cerebral cortex; 112 and 98 kDa in striatum and cerebellum; and 33 kDa in hippocampus and striatum. In lower proportions than in total brain were the peaks of 33 kDa in medulla oblongata and cerebral cortex and of 125 kDa in medulla oblongata. 相似文献
96.
97.
Mini Kapoor Roberto Montes de Oca Luna Gen Liu Guillermina Lozano Chris Cummings Michael Mancini Ilia Ouspenski B. R. Brinkley Gregory S. May 《Chromosoma》1998,107(8):570-576
Centromere protein B (CENP-B) is a centromeric DNA-binding protein that binds to α-satellite DNA at the 17 bp CENP-B box sequence.
The binding of CENP-B, along with other proteins, to α-satellite DNA sequences at the centromere, is thought to package the
DNA into heterochromatin subjacent to the kinetochore of mitotic chromosomes. To determine the importance of CENP-B to kinetochore
assembly and function, we generated a mouse null for the cenpB gene. The deletion removed part of the promoter and the entire coding sequence except for the carboxyl-terminal 35 amino
acids of the CENP-B polypeptide. Mice heterozygous or homozygous for the cenpB null mutation are viable and healthy, with no apparent defect in growth and morphology. We have established mouse embryo
fibroblasts from heterozygous and homozygous cenpB null littermates. Microscopic analysis, using immunofluorescence and electron microscopy of the cultured cells, indicated
that the centromere-kinetochore complex was intact and identical to control cells. Mitosis was identical in fibroblasts derived
from cenpB wild-type, heterozygous and null animals. Our studies demonstrate that CENP-B is not required for the assembly of heterochromatin
or the kinetochore, or for completion of mitosis.
Received: 17 September 1998 / Accepted: 9 October 1998 相似文献
98.
Salgado-Maldonado G Moravec F Cabañas-Carranza G Aguilar-Aguilar R Sánchez-Nava P Báez-Valé R Scholz T 《The Journal of parasitology》2004,90(2):260-265
A total of 8 helminth species were recorded in an examination of 43 tropical gar, Atractosteus tropicus Gill, collected at the Pantanos de Centla Biosphere Reserve, Tabasco, Mexico. The parasite species included 1 adult trematode, 3 metacercariae, 1 cestode, 1 adult nematode, and 2 nematode larvae. Six of these 8 species were rare, with low prevalence (< 17%) and abundance (< 1.0 helminths per examined fish). The larvae of Contracaecum sp. were the most abundant in the sample, constituting 60% of the total helminths (64% prevalence, 3.8 +/- 5.2 abundance), followed by the cestode Proteocephalus singularis, constituting 18% of the worms (30.5% prevalence, 1.1 +/- 3.0 abundance). Species richness, individual parasite abundance, and diversity were low in the infracommunities. The recording of 3 specialist species in the tropical gar confirms that the helminth fauna of gar has an appreciable degree of specificity. This study indicates the importance of ecological determinants of richness in helminth communities of the tropical gar. 相似文献
99.
TNF-alpha is a critical effector and a target for therapy in antiphospholipid antibody-induced pregnancy loss 总被引:9,自引:0,他引:9
The antiphospholipid syndrome (APS) is characterized by recurrent fetal loss, intrauterine growth restriction, and vascular thrombosis in the presence of antiphospholipid (aPL) Abs. Our studies in a murine model of APS induced by passive transfer of human aPL Abs have shown that activation of complement and recruitment of neutrophils into decidua are required for fetal loss, and emphasize the importance of inflammation in aPL Ab-induced pregnancy loss. In this study, we examine the role of TNF-alpha in pregnancy complications associated with aPL Abs in a murine model of APS. We show that aPL Abs are specifically targeted to decidual tissue and cause a rapid increase in decidual and systemic TNF-alpha levels. We identify the release of TNF-alpha as a critical intermediate that acts downstream of C5 activation, based on the fetal protective effects of TNF-alpha deficiency and TNF blockade and on the absence of increased TNF-alpha levels in C5-deficient mice treated with aPL Abs. Our results suggest that TNF-alpha links pathogenic aPL Abs to fetal damage and identify TNF blockade as a potential therapy for the pregnancy complications of APS. 相似文献
100.