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排序方式: 共有653条查询结果,搜索用时 15 毫秒
1.
Paola G. Andreis Piera Rebuffat Anna S. Belloni Giuliano Neri Letizia Cavallini Giuseppe Gottardo Giuseppina Mazzocchi Alberta Coi Ludwik K. Malendowicz Dr. Gastone G. Nussdorfer 《Cell and tissue research》1989,258(1):43-51
Summary The morphology and function of isolated inner (zona fasciculata/reticularis) adrenocortical cells of rats pretreated with ACTH for 3, 6, 9 or 12 days were investigated. ACTH treatment induced a notable time-dependent enhancement in the steroidogenic capacity (corticosterone production) and growth of inner cells. The volumes of cells, mitochondrial compartment, membrane space [the cellular space occupied by smooth endoplasmic reticulum (SER) membranes] and lipid-droplet compartment, as well as the surface area of mitochondrial cristae and SER tubules, were increased in relation to the duration of ACTH pretreatment, and showed a highly significant positive linear correlation with both basal and stimulated corticosterone production. The acute exposure of isolated cells to ACTH provoked a striking lipid-droplet depletion, the extent of which was linearly and positively correlated with stimulated corticosterone secretion. The hypertrophy of the mitochondrial compartment and SER are interpreted as the morphological counterpart of the enhanced steroidogenic capacity of inner adrenocortical cells, inasmuch as the enzymes of steroid synthesis are located in these two organelles, and it is well known that chronic ACTH exposure stimulates the de novo synthesis of many of them in vivo. The rise in the number of lipid droplets, in which cholesterol is stored, is interpreted as being due to the fact that, under chronic ACTH treatment, the processes leading to cholesterol accumulation in adrenocortical cells (exogenous uptake and endogenous synthesis) exceed those of its utilization in basal steroid secretion. Cholesterol accumulated in lipid droplets as a reserve material may be rapidly utilized after acute ACTH exposure to meet the needs of the enhanced steroidogenic capacity of adrenocortical cells. 相似文献
2.
Raffaella Scardigli Silvia Soddu Rita Falcioni Marco Crescenzi Letizia Cimino Ada Sacchi 《Experimental cell research》1996,227(2):223
Integrin β4subunit is present in association with α6chain on both normal and transformed epithelial cells. Recently α6β4heterodimer was found on the endothelium of medium-sized blood vessels and on immature thymocytes. In this report we show, by Northern blotting, indirect immunofluorescence, immunoprecipitation, and Western blotting, that β4subunit is expressed also on cells of mesenchymal origin such as fibroblasts, myoblasts, and myotubes. Increased expression of α6β4has been related to the aggressive metastatic phenotype of human and murine carcinomas. The transforming growth factor β1(TGF-β1) has been found to modulate the expression of several integrins and intracellular matrix proteins, as well as to stimulate cell invasion and metastatic potential. To evaluate whether α6β4expression is modulated by TGF-β1, we transfected 3T3 fibroblasts with an expression vector carrying the human TGF-β1cDNA driven by the SV40 early promoter. We observed by indirect immunofluorescence a modification in the subcellular distribution of β4subunit, which acquires a perinuclear localization. This finding suggests this integrin subunit correlates with the cytoskeletal reorganization induced by TGF-β1. 相似文献
3.
Bloom Syndrome and Maternal Uniparental Disomy for Chromosome 15 总被引:4,自引:1,他引:3
Trevor Woodage Madhuri Prasad Joanne W. Dixon Roslyn E. Selby Dennis R. Romain Letizia M. Columbano-Green David Graham Peter K. Rogan James R. Seip Arabella Smith Ronald J. Trent 《American journal of human genetics》1994,55(1):74-80
Bloom syndrome (BS) is an autosomal recessive disorder characterized by increases in the frequency of sister-chromatid exchange and in the incidence of malignancy. Chromosome-transfer studies have shown the BS locus to map to chromosome 15q. This report describes a subject with features of both BS and Prader-Willi syndrome (PWS). Molecular analysis showed maternal uniparental disomy for chromosome 15. Meiotic recombination between the two disomic chromosomes 15 has resulted in heterodisomy for proximal 15q and isodisomy for distal 15q. In this individual BS is probably due to homozygosity for a gene that is telomeric to D15S95 (15q25), rather than to genetic imprinting, the mechanism responsible for the development of PWS. This report represents the first application of disomy analysis to the regional localization of a disease gene. This strategy promises to be useful in the genetic mapping of other uncommon autosomal recessive conditions. 相似文献
4.
P. Cugini C. Letizia S. Cerci L. Di Palma P. Battisti A. Coppola D. Scavo 《Chronobiology international》1993,10(2):119-122
This study deals with a chronobiological approach to the circadian rhythm of the renin-angiotensin-aldosterone system (RAAS) and the ACTH-cor-tisol axis (ACA) in patients with Addison's disease (PAD). The aim is to explore the mechanism(s) for which the circadian rhythmicity of the RAAS and ACA takes place. The study has shown that both the RAAS and ACA are devoid of a circadian rhythm in PAD. The lack of rhythmicity for renin and ACTH provides indirect evidence that their rhythmic secretion is in some way related to the circadian oscillation of aldosterone and cortisol. This implies a new concept: a positive feedback may be included among the mechanisms which chronoregulate the RAAS and ACA. 相似文献
5.
We investigated patterns of resource partitioning between two brackish crustaceans (I. baltica and G. insensibilis) on trophic mosaics of fungal species colonizing vegetal detritus. Laboratory feeding experiments were carried out to assess consumption rates and diet selection of single individuals belonging to five populations. Adults of two co-occurring population of both G. insensibilis and I. baltica and one population of G. insensibilis, occurring alone in another habitat patch, were studied. Each individual were offered both fragments of Cymodocea nodosa conditioned by 8 fungal species and sterilized fragments as sole food source for 7 days. Both species preferred "conditioned" detritus but potential resource use was greater in G. insensibilis than in I. baltica. Individual niche breadth increased and phenotypic variability reduced in the allotopic sample. Trophic similarities were lower between individuals of co-occuring populations than between I. baltica and the allotopic G. insensibilis. The results suggest that co-occurrence is an important factor contributing to the enhancement of phenotypic variability and, consequently, to a trophic generalization at population level in G. insensibilis. It emphasizes the role of fungal patchiness on detritus in regulating resource partitioning between the two species. 相似文献
6.
The circadian rhythm of serum angiotensin-converting enzyme (ACE) activity was investigated in pregnant women with normal and pre-eclamptic gestation. The chronobiological approach was able to document the occurrence of a circadian rhythm for serum ACE activity in normal pregnancy. Such a rhythm is characterized by a decreased mesor and amplitude and a shifted crest. The circadian rhythm for serum ACE activity was not detectable in pre-eclamptic pregnancy. Such an abrogation is accompanied by a negligible decrease of mesor suggesting the occurrence of a relative hyperACEemia. This disorder could play a role in pregnancy-induced hypertension. 相似文献
7.
8.
Penolazzi L Lambertini E Tavanti E Torreggiani E Vesce F Gambari R Piva R 《Cell biology international》2008,32(2):320-325
We have used cytokine protein array to analyze the secretion of cytokines from an osteoblastic clone derived from human umbilical cord blood mesenchymal stem cells (MSCs) cultured in an osteogenic differentiation medium. The analysis demonstrated the unexpected ability of osteoblast committed cells and their early progenitors to produce significant amounts of a range of soluble immune mediators without in vitro exposure to clinically relevant bacterial pathogens. The cells were expanded and their osteogenic potential analyzed over 45 days of culture was revealed by the expression of osteoblast-specific markers (alkaline phosphatase and Runx2), and by matrix mineralization. Over this culture period, the cells secreted particularly high levels of IL-8, MCP-1 and VEGF, but did not express IL-2, IL-7, IL-17, eotaxin, G-CSF and IFN-gamma. These findings should encourage the use of human umbilical cord blood as a potential stem cells source for bone regeneration. 相似文献
9.
Tyler J. Clark Anne‐Sophie Bonnet‐Lebrun Letizia Campioni Paulo Catry Ewan Wakefield 《Ibis》2019,161(1):192-197
The Sooty Shearwater Ardenna grisea, an abundant but declining petrel, is one of many seabird species that construct breeding burrows, presumably because these confer protection from predators and the elements. Little is known about the causes of variation in Sooty Shearwater burrow architecture, which can differ markedly both within and between breeding sites. We hypothesize that burrow architecture varies in response to habitat type and competition for space. To address these hypotheses, we recorded Sooty Shearwater burrow dimensions on Kidney Island, the largest Sooty Shearwater colony in the Falkland Islands, South Atlantic, and modelled these as functions of burrow density (a proxy for competition) and habitat indices. Our models suggest that Sooty Shearwaters burrow further underground in response to competition for breeding space, and that soil underlying dense tussac grass Poa flabellata is more easily excavated than other substrates, indicating how vegetation restoration could aid the conservation of this species. 相似文献
10.
F Trovato 《Social biology》1992,39(1-2):82-101
For most people immigration to a new country such as Canada entails a positive move and an improvement in life. The many challenges associated with resettlement may, however, lead to insurmountable difficulties, stresses and conflict for a significant number of newcomers. The mortality experience of immigrants, as reflected in cause-of-death statistics, may provide indication of the extent of stress and conflict in their migration experience. This situation is most clearly exhibited in mortality from suicide, homicide, and motor vehicle accidents. In this study, hypotheses concerning immigrant mortality in Canada are developed and tested with a log-linear model for rates pertaining to rare events. Overall, the results give support for the importance of country-of-origin effects in explaining suicide propensities, but not for homicide and motor vehicle accidents mortality. Income discrepancies are a significant determinant of variability in death rates overall, but discrepancies between the immigrants in this study and the Canadian-born are not of much significance. The strongest net effect on the cause-specific death rate is associated with group membership. This effect likely reflects a number of residual unmeasured sources of variation including the influence of the immigrant ethnic community as a source of social support, and the potential confounding effects of migration selectivity. 相似文献