Challenges in the prenatal and post-natal diagnosis of mediastinal cystic hygroma: a case report

<p>Abstract</p> <p>Introduction</p> <p>Cystic hygroma is a benign congenital neoplasm that mostly presents as a soft-tissue mass in the posterior triangle of the neck. Pure mediastinal lesions are uncommon; the vast majority are asymptomatic and are an incidental finding in adulthood. The diagnosis is often made intra- or postoperatively. Prenatal identification is exceptional and post-natal diagnosis also proves challenging.</p> <p>Case presentation</p> <p>We report one such case that was mistaken for other entities in both the prenatal and immediate post-natal period. Initial and follow-up antenatal ultrasound scans demonstrated a multicystic lesion in the left chest, and the mother was counselled about the possibility of her baby having a congenital diaphragmatic hernia. Initial post-natal chest radiographs were reported as normal. An echocardiogram and thoracic computed tomography scan confirmed a complex multiloculated cystic mediastinal mass. The working diagnoses were of a mediastinal teratoma or congenital cystic adenomatous malformation. At operation, the lesion was compressed by the left lung and was found to be close to the left phrenic nerve, which was carefully identified and preserved. After excision, histopathological examination of the mass confirmed the diagnosis of cystic hygroma. Postoperative dyspnoea was observed secondary to paradoxical movement of the left hemidiaphragm and probable left phrenic neuropraxia. This settled conservatively with excellent recovery.</p> <p>Conclusion</p> <p>Despite the fact that isolated intrathoracic cystic hygroma is a rare entity, it needs to be considered in the differential diagnosis of foetal and neonatal mediastinal masses, particularly for juxtadiaphragmatic lesions. The phrenic nerve is not identifiable on prenatal ultrasound imaging, and it is therefore understandable that a mass close to the diaphragm may be mistaken for a congenital diaphragmatic hernia because of the location, morphology and potential phrenic nerve compression. Post-natal diagnosis may also be misleading as many mediastinal cystic masses have similar appearances on imaging. Therefore, as well as cystic architecture, special consideration needs to be given to the anatomical location and effect on local structures.</p

Understory Bird Communities in Amazonian Rainforest Fragments: Species Turnover through 25 Years Post-Isolation in Recovering Landscapes

Inferences about species loss following habitat conversion are typically drawn from short-term surveys, which cannot reconstruct long-term temporal dynamics of extinction and colonization. A long-term view can be critical, however, to determine the stability of communities within fragments. Likewise, landscape dynamics must be considered, as second growth structure and overall forest cover contribute to processes in fragments. Here we examine bird communities in 11 Amazonian rainforest fragments of 1–100 ha, beginning before the fragments were isolated in the 1980s, and continuing through 2007. Using a method that accounts for imperfect detection, we estimated extinction and colonization based on standardized mist-net surveys within discreet time intervals (1–2 preisolation samples and 4–5 post-isolation samples). Between preisolation and 2007, all fragments lost species in an area-dependent fashion, with loss of as few as <10% of preisolation species from 100-ha fragments, but up to 70% in 1-ha fragments. Analysis of individual time intervals revealed that the 2007 result was not due to gradual species loss beginning at isolation; both extinction and colonization occurred in every time interval. In the last two samples, 2000 and 2007, extinction and colonization were approximately balanced. Further, 97 of 101 species netted before isolation were detected in at least one fragment in 2007. Although a small subset of species is extremely vulnerable to fragmentation, and predictably goes extinct in fragments, developing second growth in the matrix around fragments encourages recolonization in our landscapes. Species richness in these fragments now reflects local turnover, not long-term attrition of species. We expect that similar processes could be operating in other fragmented systems that show unexpectedly low extinction

REMOTE FIBEROPTIC CHEMICAL SENSING USING EVANESCENT-WAVE INTERACTIONS IN CHALCOGENIDE GLASS-FIBERS

An infrared-transmitting chalcogenide fiber was used as an optical probe to analyze qualitatively and quantitatively various chemical substances in aqueous solutions. An unclad fiber with 380-mu-m diameter was combined with a Fourier transform infrared spectrometer to monitor the concentration of the analytes in solutions by measuring the changes in the absorbance of their fundamental vibration peaks. A linear relationship was observed between the absorption by the evanescent field and concentrations of various analytes. For this study low concentrations of acetone, ethyl alcohol, and sulfuric acid were detected in aqueous solutions. The minimum detection limit for these three chemical substances was 5, 3, and 2 vol. %, respectively, with a sensor length of 15 cm. It was also demonstrated that the same sensor design is capable of monitoring gaseous species such as dichlorodifluoromethane.X1198sci

SPECTROSCOPIC ANALYSIS OF THE STRUCTURE AND PROPERTIES OF ALKALI TELLURITE GLASSES

Structural development of tellurite glasses with the addition of Li2O and Na2O has been studied using infrared, Raman, and X-ray photoelectron spectroscopies. The increase in intensity of the peak at 755 cm-1 in the infrared spectra as compared to the peak at 620 cm-1 suggests the transformation of TeO4 building units to TeO3 pyramids with the addition of alkali oxide. Proposed structural change is further supported by the strong compositional dependence of the 755-cm-1 peak in the Raman spectra as well as by the formation of a shoulder in the O 1s peak of X-ray photoelectron spectra. In contrast to alkali silicate glasses, formation of nonbridging oxygens with the addition of alkali oxide is not observed.X11102sciescopu

Influence of decreasing solvent polarity (1,4-dioxane/water mixtures) on the stability and structure of complexes formed by copper(II), 2,2`-bipyridine or 1,10-phenanthroline and guanosine 5`-diphosphate : evaluation of isomeric equilibria

The stability constants of the 1 : 1 complexes formed between Cu(Arm)2+, where Arm = 2,2`-bipyridine or 1,10-phenanthroline, and guanosine 5`-diphosphate (GDP)3- or its monoprotonated form H(GDP)2- were determined by potentiometric pH titrations in water and in water containing 30 or 50 stability of the binary Cu(GDP)- complex is enhanced due to macrochelate formation of the diphosphate-coordinated Cu2+ with N7 of the guanine residue as previously shown. In Cu(Arm)(GDP)- the N7 is released from Cu2+ and the stability enhancement of more than one log unit in aqueous solution is clearly attributable to intramolecular stack formation between the aromatic rings of Arm and the guanine moiety. Indeed, stacked isomers occur to more than 90 with open unstacked forms. Surprisingly, the same formation degrees of the stacks are observed for Cu(Arm)(dGMP) complexes, where dGMP2- = 2`-deoxyguanosine 5`-monophosphate, despite the fact that the overall stability of the latter species is by about 2.7 log units lower. In 1,4-dioxane-water mixtures stack formation is drastically reduced, probably due to hydrophobic solvation of the aromatic rings by the ethylene bridges of 1,4-dioxane. The relevance of these results regarding biological systems is indicated

Solution structure of a DNA double helix with consecutive metal-mediated base pairs

Metal-mediated base pairs represent a powerful tool for the site-specific functionlization of nucleic acids with metal ions. The development of applications of the metal-modified nucleic acids will depend on the availability of structural information on these double helices. We present here the NMR solution structure of a self-complementary DNA oligonucleotide with three consecutive imidazole nucleotides in its centre. In the absence of transition-metal ions, a hairpin structure is adopted with the artifical nucleotides forming the loop. In the presence of Ag(I) ions, a duplex comprising three imidazole-Ag+-imidazole base pairs is formed. Direct proof for the formation of metal-mediated base pairs was obtained from (1)J(N-15,Ag-107/109) couplings upon incorporation of N-15-labelled imidazole. The duplex adopts a B-type conformation with only minor deviations in the region of the artifical bases. This work represents the first structural characterization of a metal-modified nucleic acid with a continuous stretch of metal-mediated base pairs