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941.
Pietro Cignini Maurizio Giorlandino Pierpaolo Brutti Lucia Mangiafico Alessia Aloisi Claudio Giorlandino 《PloS one》2016,11(1)
Objective
To establish reference charts for fetal cerebellar vermis height in an unselected population.Methods
A prospective cross-sectional study between September 2009 and December 2014 was carried out at ALTAMEDICA Fetal–Maternal Medical Centre, Rome, Italy. Of 25203 fetal biometric measurements, 12167 (48%) measurements of the cerebellar vermis were available. After excluding 1562 (12.8%) measurements, a total of 10605 (87.2%) fetuses were considered and analyzed once only. Parametric and nonparametric quantile regression models were used for the statistical analysis. In order to evaluate the robustness of the proposed reference charts regarding various distributional assumptions on the ultrasound measurements at hand, we compared the gestational age-specific reference curves we produced through the statistical methods used. Normal mean height based on parametric and nonparametric methods were defined for each week of gestation and the regression equation expressing the height of the cerebellar vermis as a function of gestational age was calculated. Finally the correlation between dimension/gestation was measured.Results
The mean height of the cerebellar vermis was 12.7mm (SD, 1.6mm; 95% confidence interval, 12.7–12.8mm). The regression equation expressing the height of the CV as a function of the gestational age was: height (mm) = -4.85+0.78 x gestational age. The correlation between dimension/gestation was expressed by the coefficient r = 0.87.Conclusion
This is the first prospective cross-sectional study on fetal cerebellar vermis biometry with such a large sample size reported in literature. It is a detailed statistical survey and contains new centile-based reference charts for fetal height of cerebellar vermis measurements. 相似文献942.
943.
Oxygen uptake rates of undisturbed sediment columns have been used as an integrative measure of the metabolic activities of benthic communities. Since the intensity of metabolic processes of profundal lake is dependent on the production of organic matter in the pelagic zone, oxygen uptake rates reflect the trophic condition of the whole lake. Four small lakes of central Chile, differing strongly in trophic conditions, provided a possibility to compare benthic oxygen uptake rates, under different oxygen conditions (Quiñenco, Grande, Chica and Lleulleu). Our objective was to establish the relationship between the oxygen uptake rates and bottom characteristics of lakes with different trophic conditions. At 8 mg O2 l-1 in the overlying water of the cores studied, the oxygen uptake rates of the sediment were: Quiñenco 51.2–56.0 mg O2 m2 h-1 (eutrophic), Grande 41.2–46.4 mg O2 m2 h-1 (mesotrophic), Chica 23.2–18.1 mg O2 m2 h-1 (mesotrophic) and Lleulleu 11.7–16.0 mg O2 m2 h-1 (oligotrophic). By exposing the sediments to different oxygen levels in the laboratory, it was found that benthic community metabolism decreased with oxygen concentrations. The slope of regression lines, relating oxygen uptake rates to oxygen concentrations, differed for the different sites investigated, closely related with the trophic conditions of the lakes. It was positively correlated with the organic matter content of the sediment of the cores (r
2= 0.78, p<0,05) and the nutrients of the bottom waters (total-P: r
2= 0.73, p<0,05; total-N: r
2= 0.73, p<0,05), and negatively with the redox potential of the sediments (r
2= 0.88, p<0,05). 相似文献
944.
Hurtado-Guzmán C Fierro A Iturriaga-Vásquez P Sepúlveda-Boza S Cassels BK Reyes-Parada M 《Journal of enzyme inhibition and medicinal chemistry》2003,18(4):339-347
(+/-)-4-Methylthioamphetamine (MTA) was resolved into its enantiomers, and a series of N-alkyl derivatives of the parent compound, as well as its alpha-ethyl analogue, were prepared. The monoamine oxidase (MAO) inhibitory properties of these substances were evaluated in vitro, using a crude rat brain mitochondrial suspension as the source of enzyme. All compounds produced a selective, reversible and concentration-related inhibition of MAO-A. (+)-MTA proved to be the most potent inhibitor studied, while all the other derivatives were less active than the parent compound, with (-)-MTA being about 18 times less potent than the (+) isomer. The analysis of structure-activity relationships indicates that the introduction of alkyl substituents on the amino group of MTA leads to a reduction in the potency of the derivatives as MAO-A inhibitors, an effect which increases with the size of the substituent. 相似文献
945.
Exceptional chromosomal variability makesCtenomys an excellent model for evolutionary cytogenetic analysis. Six species belonging to three evolutionary lineages were studied
by means of restriction endonuclease and C-chromosome banding. The resulting banding patterns were used for comparative analysis
of heterochromatin distribution on chromosomes. This combined analysis allowed intra- and inter-specific heterochromatin variability
to be detected, groups of species belonging to different lineages to be characterized, and phylogenetic relationships hypothesized
from other data to be supported. The “ancestral group”,Ctenomys pundti andC. talarum, share three types of heterochromatin, the most abundant of which was also found in C. aff.C. opimus, suggesting that the latter species also belongs to the “ancestral group”. Additionally, within the subspeciesC. t. talarum, putative chromosomal rearrangements distinguishing two of the three chromosomal races were identified. Two species belong
to an “eastern lineage”,C. osvaldoreigi andC. rosendopascuali, and share only one type of heterochromatin homogeneously distributed across their karyotypes.C. latro, the only analyzed species from the “chacoan” lineage, showed three types of heterochromatin, one of them being that which
characterizes the “eastern lineage”.C. aff.C. opimus, because of its low heterochromatin content, is the most primitive karyotype of the genus yet described. The heterochromatin
variability showed by these species, reflecting the evolutionary divergence toward different heterochromatin types, may have
diverged since the origin of the genus. Heterochromatin amplification is proposed as a trend withinCtenomys, occurring independently of chromosomal change in diploid numbers. 相似文献
946.
In this article, a neural model for generating and learning a rapid ballistic movement sequence in two-dimensional (2D) space
is presented and evaluated in the light of some considerations about handwriting generation. The model is based on a central
nucleus (called a planning space) consisting of a fully connected grid of leaky integrators simulating neurons, and reading
an input vector Ξ (t) which represents the external movement of the end effector. The movement sequencing results in a succession of motor strokes
whose instantiation is controlled by the global activation of the planning space as defined by a competitive interaction between
the neurons of the grid. Constraints such as spatial accuracy and movement time are exploited for the correct synchronization
of the impulse commands. These commands are then fed into a neuromuscular synergy whose output is governed by a delta lognormal
equation. Each movement sequence is memorized originally as a symbolic engram representing the sequence of the principal reference
points of the 2D movement. These points, called virtual targets, correspond to the targets of each single rapid motor stroke
composing the movement sequence. The task during the learning phase is to detect the engram corresponding to a new observed
movement; the process is controlled by the dynamics of the neural grid.
Received: 16 March 1995/Accepted in revised form: 25 July 1995 相似文献
947.
948.
Rawson PM Molette C Videtta M Altieri L Franceschini D Donato T Finocchi L Propato A Paroli M Meloni F Mastroianni CM d'Ettorre G Sidney J Sette A Barnaba V 《Nature medicine》2007,13(12):1431-1439
We found that the proteome of apoptotic T cells includes prominent fragments of cellular proteins generated by caspases and that a high proportion of distinct T cell epitopes in these fragments is recognized by CD8+ T cells during HIV infection. The frequencies of effector CD8+ T cells that are specific for apoptosis-dependent epitopes correlate with the frequency of circulating apoptotic CD4+ T cells in HIV-1-infected individuals. We propose that these self-reactive effector CD8+ T cells may contribute to the systemic immune activation during chronic HIV infection. The caspase-dependent cleavage of proteins associated with apoptotic cells has a key role in the induction of self-reactive CD8+ T cell responses, as the caspase-cleaved fragments are efficiently targeted to the processing machinery and are cross-presented by dendritic cells. These findings demonstrate a previously undescribed role for caspases in immunopathology. 相似文献
949.
Waddington SN McVey JH Bhella D Parker AL Barker K Atoda H Pink R Buckley SM Greig JA Denby L Custers J Morita T Francischetti IM Monteiro RQ Barouch DH van Rooijen N Napoli C Havenga MJ Nicklin SA Baker AH 《Cell》2008,132(3):397-409
Adenoviruses are used extensively as gene transfer agents, both experimentally and clinically. However, targeting of liver cells by adenoviruses compromises their potential efficacy. In cell culture, the adenovirus serotype 5 fiber protein engages the coxsackievirus and adenovirus receptor (CAR) to bind cells. Paradoxically, following intravascular delivery, CAR is not used for liver transduction, implicating alternate pathways. Recently, we demonstrated that coagulation factor (F)X directly binds adenovirus leading to liver infection. Here, we show that FX binds to the Ad5 hexon, not fiber, via an interaction between the FX Gla domain and hypervariable regions of the hexon surface. Binding occurs in multiple human adenovirus serotypes. Liver infection by the FX-Ad5 complex is mediated through a heparin-binding exosite in the FX serine protease domain. This study reveals an unanticipated function for hexon in mediating liver gene transfer in vivo. 相似文献