Preferential Occupancy of R2 Retroelements on the B Chromosomes of the Grasshopper Eyprepocnemis plorans

R2 non-LTR retrotransposons exclusively insert into the 28S rRNA genes of their host, and are expressed by co-transcription with the rDNA unit. The grasshopper Eyprepocnemis plorans contains transcribed rDNA clusters on most of its A chromosomes, as well as non-transcribed rDNA clusters on the parasitic B chromosomes found in many populations. Here the structure of the E. plorans R2 element, its abundance relative to the number of rDNA units and its retrotransposition activity were determined. Animals screened from five populations contained on average over 12,000 rDNA units on their A chromosomes, but surprisingly only about 100 R2 elements. Monitoring the patterns of R2 insertions in individuals from these populations revealed only low levels of retrotransposition. The low rates of R2 insertion observed in E. plorans differ from the high levels of R2 insertion previously observed in insect species that have many fewer rDNA units. It is proposed that high levels of R2 are strongly selected against in E. plorans, because the rDNA transcription machinery in this species is unable to differentiate between R2-inserted and uninserted units. The B chromosomes of E. plorans contain an additional 7,000 to 15,000 rDNA units, but in contrast to the A chromosomes, from 150 to over 1,500 R2 elements. The higher concentration of R2 in the inactive B chromosomes rDNA clusters suggests these chromosomes can act as a sink for R2 insertions thus further reducing the level of insertions on the A chromosomes. These studies suggest an interesting evolutionary relationship between the parasitic B chromosomes and R2 elements.This study was supported by grants from the Spanish Ministerio de Ciencia y Tecnología (CGL2009-11917) and Plan Andaluz de Investigacion (CVI-6649), and was partially performed by FEDER funds and a grant from the National Institutes of Health (GM42790)

Asymptomatic internal carotid artery stenosis and cerebrovascular risk stratification

Background The purpose of this study was to determine the cerebrovascular risk stratification potential of baseline degree of stenosis, clinical features, and ultrasonic plaque characteristics in patients with asymptomatic internal carotid artery (ICA) stenosis. Methods This was a prospective, multicenter, cohort study of patients undergoing medical intervention for vascular disease. Hazard ratios for ICA stenosis, clinical features, and plaque texture features associated with ipsilateral cerebrovascular or retinal ischemic (CORI) events were calculated using proportional hazards models. Results A total of 1121 patients with 50% to 99% asymptomatic ICA stenosis in relation to the bulb (European Carotid Surgery Trial [ECST] method) were followed-up for 6 to 96 months (mean, 48). A total of 130 ipsilateral CORI events occurred. Severity of stenosis, age, systolic blood pressure, increased serum creatinine, smoking history of more than 10 pack-years, history of contralateral transient ischemic attacks (TIAs) or stroke, low grayscale median (GSM), increased plaque area, plaque types 1, 2, and 3, and the presence of discrete white areas (DWAs) without acoustic shadowing were associated with increased risk. Receiver operating characteristic (ROC) curves were constructed for predicted risk versus observed CORI events as a measure of model validity. The areas under the ROC curves for a model of stenosis alone, a model of stenosis combined with clinical features and a model of stenosis combined with clinical, and plaque features were 0.59 (95% confidence interval [CI] 0.54-0.64), 0.66 (0.62-0.72), and 0.82 (0.78-0.86), respectively. In the last model, stenosis, history of contralateral TIAs or stroke, GSM, plaque area, and DWAs were independent predictors of ipsilateral CORI events. Combinations of these could stratify patients into different levels of risk for ipsilateral CORI and stroke, with predicted risk close to observed risk. Of the 923 patients with <70% stenosis, the predicted cumulative 5-year stroke rate was <5% in 495, 5% to 9.9% in 202, 10% to 19.9% in 142, and <20% in 84 patients. Conclusion Cerebrovascular risk stratification is possible using a combination of clinical and ultrasonic plaque features. These findings need to be validated in additional prospective studies of patients receiving optimal medical intervention alone. Copyright © 2010 by the Society for Vascular Surgery

The size of juxtaluminal hypoechoic area in ultrasound images of asymptomatic carotid plaques predicts the occurrence of stroke

Objective: To test the hypothesis that the size of a juxtaluminal black (hypoechoic) area (JBA) in ultrasound images of asymptomatic carotid artery plaques predicts future ipsilateral ischemic stroke. Methods: A JBA was defined as an area of pixels with a grayscale value &lt;25 adjacent to the lumen without a visible echogenic cap after image normalization. The size of a JBA was measured in the carotid plaque images of 1121 patients with asymptomatic carotid stenosis 50% to 99% in relation to the bulb (Asymptomatic Carotid Stenosis and Risk of Stroke study); the patients were followed for up to 8 years. Results: The JBA had a linear association with future stroke rate. The area under the receiver-operating characteristic curve was 0.816. Using Kaplan-Meier curves, the mean annual stroke rate was 0.4% in 706 patients with a JBA &lt;4 mm 2, 1.4% in 171 patients with a JBA 4 to 8 mm2, 3.2% in 46 patients with a JBA 8 to 10 mm2, and 5% in 198 patients with a JBA &gt;10 mm2 (P &lt;.001). In a Cox model with ipsilateral ischemic events (amaurosis fugax, transient ischemic attack [TIA], or stroke) as the dependent variable, the JBA (&lt;4 mm2, 4-8 mm2, &gt;8 mm2) was still significant after adjusting for other plaque features known to be associated with increased risk, including stenosis, grayscale median, presence of discrete white areas without acoustic shadowing indicating neovascularization, plaque area, and history of contralateral TIA or stroke. Plaque area and grayscale median were not significant. Using the significant variables (stenosis, discrete white areas without acoustic shadowing, JBA, and history of contralateral TIA or stroke), this model predicted the annual risk of stroke for each patient (range, 0.1%-10.0%). The average annual stroke risk was &lt;1% in 734 patients, 1% to 1.9% in 94 patients, 2% to 3.9% in 134 patients, 4% to 5.9% in 125 patients, and 6% to 10% in 34 patients. Conclusions: The size of a JBA is linearly related to the risk of stroke and can be used in risk stratification models. These findings need to be confirmed in future prospective studies or in the medical arm of randomized controlled studies in the presence of optimal medical therapy. In the meantime, the JBA may be used to select asymptomatic patients at high stroke risk for carotid endarterectomy and spare patients at low risk from an unnecessary operation

113Cd-NMR and Fluorescence Studies of the Interactions between Cd(II) and Extracellular Organic Matter Released by Selenastrum capricornutum

113Cd NMR spectra were measured in solution for a series of adducts between the extracellular organic matter (EOM) of the green alga Selenastrum capricornutum and cadmium(II). From the results it appears that EOM forms complexes with Cd(II), which are in a fast exchange in NMR time scale. Thus the observed shift is the molar average of limit values for the exchanging free and bound cadmium species. Definite support for this dynamic stems from an extensive 113Cd NMR equilibrium analysis. Although in principle a multiple binding mode cannot be excluded, our 113Cd NMR findings and the consideration that carbohydrates are the prevailing constituents of algal releasing in stationary growth phase led us to suggest a carbohydrate type coordination. This hypothesis is also supported by NMR studies on model compounds. However, this is probably an oversimplified view of the binding which does not properly account for the fluorescence results. Fluorescence spectroscopy provided further evidence of the EOM binding process also allowing a discrimination between the fluorophoric groups involved. The addition of Cd(II) affected both fluorescence intensity and peak position in the "humic-like" band (between 340 and 400 nm Ex). Finally, the 113Cd NMR and synchronous fluorescence measurements showed a linear correlation between 113Cd chemical shifts and EOM concentration (as fluorescence intensity at 340 and 360 nm). NMR and fluorescence data suggest the existence of structurally different binding sites (carbohydrate-like and humic-like) which appear somehow related. Further, they definitely put in evidence the EOM-Cd interaction together with the specific organic components mostly involved

The role of T CD4+CD25+ T cells in ischemia and reperfusion injury

A insuficiência renal aguda (IRA) é uma síndrome que se desenvolve após uma interrupção súbita e transiente do fluxo sanguíneo total ou regional dos rins. A lesão por isquemia seguida de reperfusão (IR) é a maior causa de IRA, tanto em órgãos nativos, quanto em transplantados e apresenta importante implicação na patogênese do transplante e da rejeição de órgãos. Esta lesão tecidual pós-isquemia no rim não é só devida à hipóxia gerada pela interrupção de fluxo sangüíneo, mas também, ao processo de reperfusão, que envolve expressão de moléculas de adesão, recrutamento de leucócitos periféricos e proliferação de células intersticiais locais, levando à instalação de uma resposta inflamatória ativa. Os mecanismos envolvidos nestes eventos não são conhecidos, mas sabe-se hoje que o linfócito T desempenha um importante papel na patogênese da lesão tecidual. A identificação do papel das células T na lesão por IR abre diversas perspectivas para o estudo da IRA e suas altemativas terapêuticas. Uma subpopulação de células T CD4+ naturalmente emergente do timo e que expressa CD25, CTLA-4, GITR e Foxp3 constitutivamente pode suprimir a ativação e a expansão de células T auto-reativas no sistema imune normal, contribuindo assim, para a manutenção da auto-tolerância. A remoção ou redução dessa população reguladora (células T CD4+CD25j pode levar diretamente ao desenvolvimento de várias doenças auto-imunes. Sabe-se também que estas células atuam na modulação de respostas imunes contra patógenos, no entanto, não há estudos sobre o papel da população T CD4+CD25+ reguladora na lesão renal por IR. Q objetivo deste trabalho foi estudar o papel das células T CD4+ CD25+ na lesão renal por isquemia de 45 minutos e reperfusão de 24 e 72 horas, através da depleção da população reguladora, utilizando-se o anticorpo monoclonal anti-CD25 (hibridoma PC61), em camundongos C57BU6, os quais, foram, posteriormente, submetidos à cirurgia de clampeamento dos pedículos renais. Quando comparamos os valores de creatinina e uréia de IR 24 e 72 horas de grupos tratados e não tratados com PC61, nós não observamos diferença estatística significante. O tratamento com PC61 também não influenciou a recuperação que ocorreu de 24 para 72 horas em grupos tratados e não tratados. E, por fim, não detectamos expressão de Foxp3 em rins de camundongos tratados e não tratados, submetidos à IR renal de 24 e 72 horas, sugerindo que, apesar de estar demonstrado que os linfócitos T CD4+ desempenham um importante papel na patogênese da lesão por IR, a população T CD4+CD25+ não apresenta papel crucial neste modelo experimental de IR renal.BV UNIFESP: Teses e dissertaçõe

Optical Properties of the Water in the Deltaic Environment. Prospective Tool to Analyse Satellite Data in Turbid Waters.

In vivo absorption spectra, pigment concentrations from algal cultures, and field samples (Po Delta, Northern Italy, are analyzed to differentiate the contribution by each optically active constituent to the total absorption by the water. The results yeld systematic trends in the blue-red and blue-NIR absorption ratio for living phytoplankton cells and detrital material, which are then used to retrieve the absorption coefficient of dissolved organic material (yellow substance) at 410 nm from the total in vivo absorption coefficients of natural waters at 410 nm, 670 nm, and 730 nm.JRC.(SAI)-Space Application Institut

Application of Spectrofluorimetric Techniques to the Study of Marine Mucilages in the Adriatic Sea. Preliminary Results

Abstract not availableJRC.(IRSA)-Institute For Remote Sensing Application