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排序方式: 共有111条查询结果,搜索用时 265 毫秒
1.
Sara Divari Francesca Valetti Patrizia Caposio Enrica Pessione Maria Cavaletto Ersilia Griva Giorgio Gribaudo Gianfranco Gilardi Carlo Giunta 《European journal of biochemistry》2003,270(10):2244-2253
Phenol hydroxylase (PH) from Acinetobacter radioresistens S13 represents an example of multicomponent aromatic ring monooxygenase made up of three moieties: a reductase (PHR), an oxygenase (PHO) and a regulative component (PHI). The function of the oxygenase component (PHO), here characterized for the first time, is to bind molecular oxygen and catalyse the mono-hydroxylation of substrates (phenol, and with less efficiency, chloro- and methyl-phenol and naphthol). PHO was purified from extracts of A. radioresistens S13 cells and shown to be a dimer of 206 kDa. Each monomer is composed by three subunits: alpha (54 kDa), beta (38 kDa) and gamma (11 kDa). The gene encoding PHO alpha (named mopN) was cloned and sequenced and the corresponding amino acid sequence matched with that of functionally related oxygenases. By structural alignment with the catalytic subunits of methane monooxygenase (MMO) and alkene monooxygenase, we propose that PHO alpha contains the enzyme active site, harbouring a dinuclear iron centre Fe-O-Fe, as also suggested by spectral analysis. Conserved hydrophobic amino acids known to define the substrate recognition pocket, are also present in the alpha-subunit. The prevalence of alpha-helices (99.6%) as studied by CD confirmed the hypothized structural homologies between PHO and MMO. Three parameters (optimum ionic strength, temperature and pH) that affect kinetics of the overall phenol hydroxylase reaction were further analyzed with a fixed optimal PHR/PHI/PHO ratio of 2/1/1. The highest level of activity was evaluated between 0.075 and 0.1 m of ionic strength, the temperature dependence showed a maximum of activity at 24 degrees C and finally the pH for optimal activity was determined to be 7.5. 相似文献
2.
Ersilia Cassano Marco Macchia Mahmud Hamdan Paolo Rovero 《Letters in Peptide Science》1996,3(3):117-120
Summary We describe a new solid-phase strategy for the selective reduction of the C=N bond in peptide oximes using a trialkylsilane in trifluoroacetic acid. The reduction is performed directly on the resin-bound peptide, with concomitant cleavage of the peptide from the resin and deblocking of protected side chains. 相似文献
3.
Irene Colavita Nicola Esposito Concetta Quintarelli Ersilia Nigro Fabrizio Pane Margherita Ruoppolo Francesco Salvatore 《Proteomics》2013,13(16):2414-2418
In the present study, we used a functional proteomic approach to identify Annexin A1 (Anxa1) interacting proteins in the Philadelphia‐positive KCL22 cell line. We focused on Anxa1 because it is one of the major proteins upregulated in imatinib‐sensitive KCL22S cells versus imatinib‐resistant KCL22R. Our proteomic strategy revealed 21 interactors. Bioinformatic analysis showed that most of these proteins are involved in cell death processes. Among the proteins identified, we studied the interaction of Anxa1 with two phosphatases, Shp1 and Shp2, which were recently identified as biomarkers of imatinib sensitivity in patients affected by chronic myeloid leukemia. Our data open new perspectives in the search for annexin‐mediated signaling pathways and may shed light on mechanisms of resistance to imatinib that are unrelated to Bcr‐Abl activity. All mass spectrometry data have been deposited in the ProteomeXchange with identifier PXD000030. 相似文献
4.
Marina Giuliano Mauro Andreotti Giuseppe Liotta Haswell Jere Jean-Baptiste Sagno Martin Maulidi Sandro Mancinelli Ersilia Buonomo Paola Scarcella Maria F. Pirillo Roberta Amici Susanna Ceffa Stefano Vella Leonardo Palombi Maria Cristina Marazzi 《PloS one》2013,8(7)
Background
Optimized preventive strategies are needed to reach the objective of eliminating pediatric AIDS. This study aimed to define the determinants of residual HIV transmission in the context of maternal antiretroviral therapy (ART) administration to pregnant women, to assess infant safety of this strategy, and to evaluate its impact on maternal disease.Methodology/Principal Findings
A total of 311 HIV-infected pregnant women were enrolled in Malawi in an observational study and received a nevirapine-based regimen from week 25 of gestation until 6 months after delivery (end of breastfeeding period) if their CD4+ count was > 350/mm3 at baseline (n = 147), or indefinitely if they met the criteria for treatment (n. 164). Mother/child pairs were followed until 2 years after delivery. The Kaplan-Meier method was used to estimate HIV transmission, maternal disease progression, and survival at 24 months. The rate of HIV infant infection was 3.2% [95% confidence intervals (CI) 1.0-5.4]. Six of the 8 transmissions occurred among mothers with baseline CD4+ count > 350/mm3. HIV-free survival of children was 85.8% (95% CI 81.4-90.1). Children born to mothers with baseline CD4+ count < 350/mm3 were at increased risk of death (hazard ratio 2.6, 95% CI 1.1-6.1). Among women who had stopped treatment the risk of progression to CD4+ count < 350/mm3 was 20.6% (95% CI 9.2-31.9) by 18 months of drug discontinuation.Conclusions
HIV transmission in this cohort was rare however, it occurred in a significative proportion among women with high CD4+ counts. Strategies to improve treatment adherence should be implemented to further reduce HIV transmission. Mortality in the uninfected exposed children was the major determinant of HIV-free survival and was associated to maternal disease stage. Given the considerable proportion of women reaching the criteria for treatment within 18 months of drug discontinuation, life-long ART administration to HIV-infected women should be considered. 相似文献5.
Robbins MM Bermejo M Cipolletta C Magliocca F Parnell RJ Stokes E 《American journal of primatology》2004,64(2):145-159
Life-history traits and ecological conditions have an important influence on primate social systems. Most of what we know about the life-history patterns and social structure of gorillas comes from studies of eastern gorillas (Gorilla beringei sp.), which live under dramatically different ecological conditions compared to western gorillas (Gorilla gorilla sp.). In this paper we present new data on western gorilla social structure and life histories from four study sites, and make comparisons with eastern gorilla populations. Data were obtained from two study sites with gorilla groups undergoing the habituation process (Lossi, Democratic Republic of Congo and Bai Hokou, Central African Republic) and two "bai" studies (Maya Nord and Mbeli Bai, Republic of Congo). The size and structure of these groups were similar to those seen in eastern gorillas. However, differences in the occurrence of various group transitions (group formations, changes between one-male and multimale composition, and group disintegrations) exist, and western gorillas notably exhibit much higher rates of male emigration and correspondingly fewer multimale groups compared to mountain gorillas. Certain phenomena have been observed only rarely, including predation by leopards. The preliminary data show no significant differences in birth rates between western gorillas and mountain gorillas. The ecological variability across gorilla habitats likely explains the flexibility in the social system of gorillas, but we need more information on the social relationships and ecology of western gorillas to elucidate the causes for the similarities and differences between western and eastern gorillas on the levels of individuals, social groups, and population dynamics. 相似文献
6.
Endoparasites of western lowland gorillas (Gorilla gorilla gorilla) at Bai Hokou, Central African Republic 总被引:2,自引:0,他引:2
Freeman AS Kinsella JM Cipolletta C Deem SL Karesh WB 《Journal of wildlife diseases》2004,40(4):775-781
A coprologic study of free-ranging western lowland gorillas (Gorilla gorilla gorilla) at Bai Hokou, Dzangha-Ndoki National Park, Central African Republic (2 degrees 51'34'N, 16 degrees 28'03'E) was conducted from October 1999 to November 2000. All 75 fecal samples examined were positive for endoparasites, and each contained at least two species. Parasites present included two genera of amoebae, entodiniomorph ciliates, including Prototapirella gorillae, Troglodytella spp., and Gorillophilus thoracatus, a Balantidium-like organism, strongyle/trichostrongyle eggs (including a presumptive Mammomonogamus sp. and several other genera), Strongyloides sp., Probstmayria sp., a spirurid, a trichuroid, and several unidentified trematodes. Flagellates and cestodes were not found. Despite the presence of a variety of parasite genera, in general, levels of parasitism were low. These data provide baseline parasitologic data for this population as part of a comprehensive health-monitoring program. With the advent of ecotourism in this study area, continued monitoring is indicated for insuring the health of both gorillas and humans in the Bai Hokou study area. 相似文献
7.
Chloé Cipolletta Noemi Spagnoletti Angelique Todd Martha M. Robbins Heather Cohen Sarah Pacyna 《International journal of primatology》2007,28(2):457-476
Though insectivory by large-bodied gorillas may be unexpected, researchers have reported it in all populations of gorillas
studied to date. Our study of 2 well monitored groups of western gorillas (Gorilla gorilla gorilla) at Bai Hokou in Dzanga-Ndoki National Park, Central African Republic provides information on frequency and variability of
termite consumption (the most commonly eaten insect) as well as some of the first direct observations of the behavior. Pooled
data from both groups indicate termite feeding on 34% and 83% of days, through fecal analysis and feeding trails, respectively.
Direct observations revealed that termite feeding occurred on 91% of the days for 1 group, in which the silverback fed on
termites during 13% of all feeding scans, making termites the most commonly observed food item. The group that had a higher
density of termite mounds in its home range consumed termites more frequently than the other group did. A higher proportion
of fecal samples from the silverbacks contained termite remains than the ones from adult females and juveniles. Termite consumption
was lower during the dry season, but it does not correlate with rainfall, measures of fruit availability, or fruit consumption.
Displacements at termite mounds occurred more than expected, indicating that they are a patchy, sought-after food resource.
Gorillas did not use tools to extract termites, but they used 2 different techniques to remove them from the cells. Though
culture or social traditions may cause the variation in termite consumption across sites, further investigation of termite
availability and consumption is necessary to rule out ecological and methodological explanations for observed variations. 相似文献
8.
Coccaro E Mraiche F Malo M Vandertol-Vanier H Bullis B Robertson M Fliegel L 《Molecular and cellular biochemistry》2007,302(1-2):145-155
We examined two expression systems for studying the Na+/H+ exchanger in the mammalian myocardium. Mammalian NHE1 with a hemagglutinin (HA) tag and was cloned behind the alpha myosin
heavy chain promoter. Transgenic mice were made with wild type NHE1 protein or with a hyperactive NHE1 protein mutated at
the calmodulin-binding domain. Three lines of transgenic mice were made of each cDNA with expression levels of each type varying
from high to low. Higher levels and activity of the Na+/H+ exchanger were associated with decreased long-term survival of mice, and with dilated or hypertrophic cardiomyopathy. The
exogenous NHE1 protein was present in freshly made cardiomyocytes from transgenic mice, however, expression from the alpha
myosin heavy chain promoter declined rapidly and little exogenous NHE1 was apparent on the fourth day after cardiomyocyte
isolation. To express NHE1 protein in isolated cardiomyocytes, we transferred a mutated form of the protein into an adenoviral
expression system. Infection of neonatal rat cardiomyocytes resulted in robust expression of the exogenous NHE1 protein. The
mutant form of the NHE1 protein could be distinguished from the endogenous Na+/H+ exchanger by its resistance to inhibition by amiloride analogs. Our results suggest that for in vivo studies on intact hearts
and animals, expression in transgenic mice is an appropriate system, however for long-term studies on cardiomyocytes, this
model is inappropriate due to waning expression from the alpha myosin heavy chain promoter. Therefore, infection by adenovirus
is a superior system for long-term studies on cardiomyocytes in culture. 相似文献
9.
Bobba A Atlante A Moro L Calissano P Marra E 《Apoptosis : an international journal on programmed cell death》2007,12(9):1597-1610
The involvement and the role of nitric oxide (NO) as a signaling molecule in the course of neuronal apoptosis, whether unique
or modulated during the progression of the apoptotic program, has been investigated in a cellular system consisting of cerebellar
granule cells (CGCs) where apoptosis can be induced by lowering extracellular potassium. Several parameters involved in NO
signaling pathway, such as NO production, neuronal nitric oxide synthase (nNOS) expression, and cyclic GMP (cGMP) production
were examined in the presence or absence of different inhibitors. We provide evidence that nitric oxide has dual and opposite
effects depending on time after induction of apoptosis. In an early phase, up to 3 h of apoptosis, nitric oxide supports survival
of CGCs through a cGMP-dependent mechanism. After 3 h, nNOS expression and activity decreased resulting in shut down of NO
and cGMP production. Residual NO then contributes to the apoptotic process by reacting with rising superoxide anions leading
to peroxynitrite production and protein inactivation. We conclude that whilst NO over-production protects neurons from death
in the early phase of neuronal damage, its subsequent reduction may contribute to neuronal degeneration and ultimate cell
death. 相似文献
10.