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排序方式: 共有87条查询结果,搜索用时 15 毫秒
61.
Juliana R Martins Francis MF Nunes Alexandre S Cristino Zilá LP Simões Márcia MG Bitondi 《BMC molecular biology》2010,11(1):23
Background
Hexamerins are hemocyanin-derived proteins that have lost the ability to bind copper ions and transport oxygen; instead, they became storage proteins. The current study aimed to broaden our knowledge on the hexamerin genes found in the honey bee genome by exploring their structural characteristics, expression profiles, evolution, and functions in the life cycle of workers, drones and queens. 相似文献62.
Maria Elena Gianicolo Emilio Antonio Luca Gianicolo Francesco Tramacere Maria Grazia Andreassi Maurizio Portaluri 《Cardiovascular ultrasound》2010,8(1):1-7
Background
Dynamic intraventricular obstruction has been observed in patients with left ventricular ballooning syndrome (LVBS) and has been hypothesized as a possible mechanism of the syndrome. The aim of this study was to assess the prevalence and significance of dynamic intraventricular obstruction in patients with LVBS.Methods and Results
Dobutamine stress echocardiography was carried out in 22 patients with LVBS (82% apical), all women, aged 68 ± 9 years. At baseline 1 patient had a > 30 mmHg LV gradient; during stress a LV gradient > 30 mm Hg developed in 6/21 patients (28%) and was caused by systolic anterior motion of the mitral valve in the 3 patients with severe gradient (mean 116 ± 29 mmHg), who developed mitral regurgitation and impaired apical wall motion and by obstruction at mid-ventricular level in the other 3 with a moderate gradient (mean 46 ± 16 mmHg). Compared with patients without obstruction those with obstruction had a greater mean septal thickness (11.6 ±.6 vs 9.8. ± 3, p <.01), a higher prevalence of septal hypertrophy (71% vs 7%, p <.005) and a higher peak wall motion score index (1.62 ±.4 vs 1.08 ±.4, p <.01).Conclusion
Spontaneous or dobutamine-induced dynamic LV obstruction is documented in 32% of patients with LVBS, is correlated with the presence of septal hypertrophy and may play a role in the development of LVBS in this subset of patients. In those without septal hypertrophy a dynamic obstruction is rarely induced with dobutamine and is unlikely to be a major pathogenetic factor of the syndrome. 相似文献63.
Giannessi D Del Ry S Andreassi MG Nardini V Pelosi G Colombo MG Biagini A 《Life sciences》1999,64(8):697-705
Endothelin (ET)-1 peripheral levels are high in children with respect to values of adults, but its pathophysiological significance remains to be established. In these conditions the interaction of ET-1 with its receptors may constitute a clue to the understanding of ET-1 function. Because a direct determination of ET binding sites in the heart of children is lacking, in this study we have attempted an assessment of the ET receptor status in cardiac tissue of infants (<1 year; 0.39 +/- 0.26 (SD) years, n=6) and children (1-14 years; 6.3 +/- 4.9 years, n=7) as well as an evaluation of the receptor modulation as a function of age, associated to the observed decrease of plasma ET levels between infants and children. ET-1 binding sites have also been evaluated in atrium and ventricle membranes of adult subjects recipient of cardiac transplantation (CHF) and of post-mortem cardiac specimens (autopsy) of non cardiac patients. Considering all the pediatric patients (infants +/- children) studied, an affinity constant (Kd) value of 38.2 +/- 6.1 (SEM) pM and a density (Bmax) value of 166.2 +/- 11.6 fmol/mg protein has been obtained for atrium. Similar values have been found in the ventricle. These values are significantly higher with respect to those obtained in adults: for atrial membranes, Kd = 22.2 +/- 9.7 and 11.6 +/- 1.8 pM; Bmax = 58.4 +/- 22.8 and 42.1 +/- 8.9 fmol/mg protein, respectively in explanted hearts and in post mortem specimens. No significant differences have been found in the binding parameters between infants and children, while, considering our results as a whole, a significant inverse correlation between Bmax and subject age (p<0.001) is suggested. The ET-A/ET-B ratio, evaluated by competition experiments with the specific ET-A antagonist BQ-123, was about 70:30 in pediatric patients, in both atrium and ventricle, without any difference between infants and children. Similar values for ET-A/ET-B ratio in adult CHF patients, in contrast to a reduction (significant only in ventricle) of the percent of ET-A subtype in autopsy, has been found. This is the first study concerning a direct evaluation of ET receptor status in children's hearts; the higher density of binding sites, associated to the elevation of plasma levels, could suggest a enhanced biological function of ET in children. 相似文献
64.
Approximately 100 strains derived from natural populations of Drosophila
melanogaster were tested for the presence or absence of P- element
sequences by using two molecular probes derived from internal regions of a
full-sized P element. Strains that had been collected from several
continents at varying times during the past 60 years were examined. The
oldest available strains, representing most major geographical regions of
the world, exhibited no detectable hybridization to the P-element probes.
In contrast, all recently collected natural populations that were tested
carried P-element sequences. The earliest appearance of P elements occurred
in collections made during the 1950s and early 1960s in the Americas and
during the late 1960s on other continents. The youngest strains that were
completely devoid of P elements originated in populations sampled during
the mid-1960s in America, but as late as 1974 in populations from the USSR.
There are differences in the patterns of hybridization to the two P-element
probes between populations from different geographical regions. These
differences are consistent with the varying P-M phenotypic properties of
these populations. Taken together with the results of phenotypic tests
reported in earlier studies, the available evidence is consistent with the
hypothesis of a worldwide P-element invasion of D. melanogaster during the
past 30 years and suggests that the putative invasion of the Americas
possibly preceded by approximately a decade that in Europe, Africa, and the
rest of the world.
相似文献
65.
Mitochondrial control-region sequences in two shorebird species, the turnstone and the dunlin, and their utility in population genetic studies 总被引:12,自引:0,他引:12
We determined the mitochondrial control-region sequences of five turnstones
(Arenaria interpres) and three dunlins (Calidris alpina). Comparisons
revealed that the central part (part II) is conserved relative to much more
variable parts at the beginning (part I) and the end (part III). This
pattern of sequence conservation is also found in the control regions of
other vertebrates. The average sequence divergence between turnstone and
dunlin was 21.8% for part I, 7.5% for part II, and 29.5% for part III.
Within-species sequence divergence over the entire control region was much
lower, at 0.9% for turnstones and 2.0% for dunlins. In both shorebird
species, part III contains a repetitive sequence composed only of A and C
nucleotides, which has not been found in the control regions of other
birds. A survey of the part I sequences of 25 turnstones and 25 dunlins
sampled around the world revealed that these species have very different
population genetic structures. Dunlins are not only much more
differentiated in their sequences but also have a strongly subdivided
population genetic structure. Pleistocene vicariant events combined with
strong natal philopatry and high mutation rates of the sequences are likely
responsible for this population genetic subdivision. Conversely, part I
sequences of turnstones are weakly differentiated and are geographically
unstructured. We argue that this is not the result of global gene flow but
that, instead turnstones have recently expanded from a refugial population
that was bottlenecked.
相似文献
66.
Johanna H Kattenberg Eleanor A Ochodo Kimberly R Boer Henk DFH Schallig Petra F Mens Mariska MG Leeflang 《Malaria journal》2011,10(1):1-18
Background
To prepare field sites for malaria vaccine trials, it is important to determine baseline antibody and T cell responses to candidate malaria vaccine antigens. Assessing T cell responses is especially challenging, given genetic restriction, low responses observed in endemic areas, their variability over time, potential suppression by parasitaemia and the intrinsic variability of the assays.Methods
In Part A of this study, antibody titres were measured in adults from urban and rural communities in Ghana to recombinant Plasmodium falciparum CSP, SSP2/TRAP, LSA1, EXP1, MSP1, MSP3 and EBA175 by ELISA, and to sporozoites and infected erythrocytes by IFA. Positive ELISA responses were determined using two methods. T cell responses to defined CD8 or CD4 T cell epitopes from CSP, SSP2/TRAP, LSA1 and EXP1 were measured by ex vivo IFN-γ ELISpot assays using HLA-matched Class I- and DR-restricted synthetic peptides. In Part B, the reproducibility of the ELISpot assay to CSP and AMA1 was measured by repeating assays of individual samples using peptide pools and low, medium or high stringency criteria for defining positive responses, and by comparing samples collected two weeks apart.Results
In Part A, positive antibody responses varied widely from 17%-100%, according to the antigen and statistical method, with blood stage antigens showing more frequent and higher magnitude responses. ELISA titres were higher in rural subjects, while IFA titres and the frequencies and magnitudes of ex vivo ELISpot activities were similar in both communities. DR-restricted peptides showed stronger responses than Class I-restricted peptides. In Part B, the most stringent statistical criteria gave the fewest, and the least stringent the most positive responses, with reproducibility slightly higher using the least stringent method when assays were repeated. Results varied significantly between the two-week time-points for many participants.Conclusions
All participants were positive for at least one malaria protein by ELISA, with results dependent on the criteria for positivity. Likewise, ELISpot responses varied among participants, but were relatively reproducible by the three methods tested, especially the least stringent, when assays were repeated. However, results often differed between samples taken two weeks apart, indicating significant biological variability over short intervals. 相似文献67.
Alessandro Tonacci Andrea Borghini Antonella Mercuri Giovanni Pioggia Maria Grazia Andreassi 《Journal of biomedical science》2013,20(1):57
Background
Brain- derived neurotrophic factor (BDNF) is linked to neurodegenerative diseases (e.g. Alzheimer disease and Parkinson disease) which are often characterized by olfactory impairment. A specific single nucleotide polymorphism of the BDNF gene, the Val66Met, modulates intracellular trafficking and activity-dependent secretion of BDNF protein. The aim of this study was to investigate a possible association between brain- derived neurotrophic factor Val66Met polymorphism and olfactory function, a well-known biomarker for neurodegeneration, in healthy young adults. A total of 101 subjects (45 males, age 38.7 ± 9.4 years) were assessed using the Sniffin’ Sticks Extended Test, a highly reliable commercial olfactory test composed of three sub-parts, calculating olfactory threshold (sensitivity), odor discrimination and odor identification. The Val66Met polymorphism was determined by polymerase chain reaction -restriction fragment length polymorphism (PCR-RFLP) analysis.Results
An impaired function in Met carriers was found, especially when compared to subjects with Val/Val genotype, in the threshold (5.5 ± 2.0 vs 6.5 ± 1.8, p = 0.009), discrimination (10.3± 2.5 vs 11.9 ± 2.2, p = 0.002), and identification task (13.3 ± 1.6 vs 14.1 ± 1.3, p = 0.007), as well as in the overall TDI Score (29.1 ± 4.5 vs 32.6 ± 3.9, p < 0.001).Conclusions
These findings appear to have implications for the evaluation of olfactory function and the relation of its impairment to cognitive decline and neurodegenerative disease. 相似文献68.
Phylogenetic relationships among prokaryotic and eukaryotic catalases 总被引:13,自引:1,他引:12
Seventy-four catalase protein sequences, including 29 bacterial, 8 fungal,
7 animal, and 30 plant sequences, were compiled, and 70 were used for
phylogenetic reconstruction. The core of the resulting tree revealed
unique, separate groups of plant and animal catalases, two groups of fungal
catalases, and three groups of bacterial catalases. The only overlap of
kingdoms occurred within one branch and involved fungal and bacterial
large-subunit enzymes. The other fungal branch was closely linked to the
group of animal enzymes. Group I bacterial catalases were more closely
related to the plant enzymes and contained such diverse taxa as the
Gram-positive Listeria seeligeri, Deinocococcus radiodurans, and
gamma-proteobacteria. Group III bacterial sequences were more closely
related to fungal and animal sequences and included enzymes from a broad
range of bacteria including high- and low-GC Gram positives,
proteobacteria, and a bacteroides species. Group II was composed of
large-subunit catalases from diverse sources including Gram positives
(low-GC Bacilli and high-GC Mycobacteria), proteobacteria, and species of
the filamentous fungus Aspergillus. These data can be interpreted in terms
of two gene duplication events that produced a minimum of three catalase
gene family members that subsequently evolved in response to environmental
demands. Horizontal gene transfer may have been responsible for the group
II mixture of bacterial and fungal large-subunit catalases.
相似文献
69.
70.