Sialic Acid Glycobiology Unveils Trypanosoma cruzi Trypomastigote Membrane Physiology.

Trypanosoma cruzi, the flagellate protozoan agent of Chagas disease or American trypanosomiasis, is unable to synthesize sialic acids de novo. Mucins and trans-sialidase (TS) are substrate and enzyme, respectively, of the glycobiological system that scavenges sialic acid from the host in a crucial interplay for T. cruzi life cycle. The acquisition of the sialyl residue allows the parasite to avoid lysis by serum factors and to interact with the host cell. A major drawback to studying the sialylation kinetics and turnover of the trypomastigote glycoconjugates is the difficulty to identify and follow the recently acquired sialyl residues. To tackle this issue, we followed an unnatural sugar approach as bioorthogonal chemical reporters, where the use of azidosialyl residues allowed identifying the acquired sugar. Advanced microscopy techniques, together with biochemical methods, were used to study the trypomastigote membrane from its glycobiological perspective. Main sialyl acceptors were identified as mucins by biochemical procedures and protein markers. Together with determining their shedding and turnover rates, we also report that several membrane proteins, including TS and its substrates, both glycosylphosphatidylinositol-anchored proteins, are separately distributed on parasite surface and contained in different and highly stable membrane microdomains. Notably, labeling for α(1,3)Galactosyl residues only partially colocalize with sialylated mucins, indicating that two species of glycosylated mucins do exist, which are segregated at the parasite surface. Moreover, sialylated mucins were included in lipid-raft-domains, whereas TS molecules are not. The location of the surface-anchored TS resulted too far off as to be capable to sialylate mucins, a role played by the shed TS instead. Phosphatidylinositol-phospholipase-C activity is actually not present in trypomastigotes. Therefore, shedding of TS occurs via microvesicles instead of as a fully soluble form

Antenna subtraction for gluon scattering at NNLO

We use the antenna subtraction method to isolate the double real radiation infrared singularities present in gluonic scattering amplitudes at next-to-next-to-leading order. The antenna subtraction framework has been successfully applied to the calculation of NNLO corrections to the 3-jet cross section and related event shape distributions in electron-positron annihilation. Here we consider processes with two coloured particles in the initial state, and in particular two-jet production at hadron colliders such as the Large Hadron Collider (LHC). We construct a subtraction term that describes the single and double unresolved contributions from the six-gluon tree-level process using antenna functions with initial state partons and show numerically that the subtraction term correctly approximates the matrix elements in the various single and double unresolved configurations.Comment: 71 pages, JHEP3 class; corrected typos, equivalent but more compact version of eq. (5.12), results unchange

Correlation between endometrial dating of luteal phase days 6 and 10 of the same menstrual cycle

CONTEXT: Endometrial maturation, important in the diagnosis of infertile couples, has been evaluated since 1950 using the Noyes criteria. Nevertheless, there is no consensus regarding the most suitable period of the luteal phase for performing the biopsy. OBJETIVE: This study evaluated the correlation between the histological dating of two endometrial biopsies performed in the same menstrual cycle, on luteal phase days six and ten.DESIGN: Prospective study. SETTING: Human Reproduction Division of the Federal University of São Paulo, referral center. PATIENTS:Twenty-five women complaining of infertility had their menstrual cycles monitored by ultrasound and LH plasma levels, to obtain evidence of ovulation. PROCEDURES: Endometrial biopsies were performed on luteal phase days LH+6 and LH+10 (luteal phase day 1 = LH+1 = the day that follows LH peak). Dating was done according to morphometric criteria, in which an endometrium sample is considered out of phase if the minimum maturation delay is one day. On day LH+6, blood was drawn for plasma progesterone level determination. RESULTS: All patients had an ovulatory cycle (mean LH peak: 47.4 U/L; mean follicular diameter on LH peak day: 18.9 mm; mean endometrial thickness on LH peak day: 10.3 mm; mean plasma progesterone level on day LH+6: 14.4 ng/ml). 14 patients had both biopsies in phase; 5 patients had out of phase biopsies only on day LH+6; 3 had out of phase biopsies only on day LH+10 and 3 patients had out of phase biopsies on both days. McNemar's test showed no statistical difference between these data (p>33.36%). CONCLUSIONS: The correlation found between the endometrial datings suggests that biopsies performed on either of these two days are suitable for evaluation of endometrial maturation.CONTEXTO: A verificação da maturidade endometrial, elemento diagnóstico necessário na avaliação do casal com queixa de infertilidade, vem sendo feita desde 1950 através do critério de datação histológica de Noyes. No entanto, não existe um consenso em relação ao período da fase lútea mais adequado para a colheita. OBJETIVO: Avaliar a correlação entre as datações histológicas de duas amostras de endométrio colhidas nos dias 6 e 10 da fase lútea de um mesmo ciclo menstrual. LOCAL: Setor de Reprodução Humana da Universidade Federal de São Paulo (UNIFESP). TIPO DE ESTUDO: Estudo prospectivo. Constou da comparação entre duas datações de endométrio num mesmo ciclo menstrual. PARTICIPANTES: 25 pacientes com queixa de infertilidade tiveram um ciclo menstrual monitorizado por ultra-sonografia e medida plasmática de LH, para demonstração de ovulação. PROCEDIMENTO: Biópsias de endométrio foram feitas nos dias LH+6 e LH+10 da fase lútea, considerando-se o dia seguinte ao do pico de LH como LH+1. A datação foi feita de acordo com critério morfométrico, considerando-se o endométrio como fora de fase, se o atraso de maturação mínimo fosse de um dia. No dia LH+6 foi feita dosagem de progesterona plasmática. RESULTADOS: Todas as pacientes apresentaram ciclos ovulatórios (média dos valores de pico de LH: 47,3 U/L; média dos diâmetros foliculares no dia do pico de LH: 18,9 mm; média das espessuras do endométrio no dia do pico de LH: 10,3 mm; média das concentrações de progesterona plasmática no dia LH+6: 14,4 ng/ml.). Em 14 pacientes, as duas biópsias estavam em fase. Houve atraso de maturação apenas no dia LH+6 em cinco pacientes; apenas no dia LH+10 em três pacientes e, nos dois dias, em três pacientes. Não houve diferença estatística entre esses valores (teste de McNemar, p=33,36%). CONCLUSÕES: Os resultados sugerem que a colheita do endométrio em qualquer dos dias (sexto ou décimo) da fase lútea fornece resultados semelhantes em relação à maturidade endometrial.Universidade Federal de São Paulo (UNIFESP)UNIFESPSciEL