Two decades of aortic coarctation treatment in children; evaluating techniques

ObjectiveThis study focuses on the evolution of treatment techniques for aortic coarctation in children and assesses long-term morbidity.MethodsThis retrospective cohort study evaluates patients treated for native aortic coarctation, with at least 7 years of follow-up. To assess time-related changes, three time periods were distinguished according to year of primary intervention (era 1, 2 and 3). Operative and long-term follow-up data were collected by patient record reviews.ResultsThe study population consisted of 206 patients (177 surgical and 29 catheter-based interventions), with a median follow-up of 151 months. Anterior approach with simultaneous repair of aortic arch and associated cardiac lesions was more common in the most recent era. Median age at intervention did not change over time. Reintervention was necessary in one third of the cohort with an event-free survival of 74% at 5‑year and 68% at 10-year follow-up. Reintervention rates were significantly higher after catheter-based interventions compared with surgical interventions (hazard ratio [HR] 1.8, 95% confidence interval [CI] 1.04–3.00, p = 0.04) and in patients treated before 3 months of age (HR 2.1, 95% CI 1.27–3.55, p = 0.003). Hypertension was present in one out of five patients.ConclusionNowadays, complex patients with associated cardiac defects and arch hypoplasia are being treated surgically on bypass, whereas catheter-based intervention is introduced for non-complex patients. Reintervention is common and more frequent after catheter-based intervention and in surgery under 3 months of age. One fifth of the 206 patients remained hypertensive.     

Intracellular calcium buffering capacity in isolated squid axons

Changes in ionized calcium were studied in axons isolated from living squid by measuring absorbance of the Ca binding dye Arsenazo III using multiwavelength differential absorption spectroscopy. Absorption changes measured in situ were calibrated in vitro with media of ionic composition similar to axoplasm containing CaEGTA buffers. Calcium loads of 50-2,500 μmol/kg axoplasm were induced by microinjection, by stimulation in 112 mM Ca seawater, or by soaking in choline saline with 1-10 mM Ca. Over this range of calcium loading of intact axoplasm, the ionized calcium in the axoplasm rose about 0.6 nM/μM load. Similar loading in axons preteated with carbonyl cyanide 4- trifluoromethoxyphenylhydrazone (FCCP) to inhibit the mitochondrial proton gradient increased ionized calcium by 5-7 percent of the imposed load, i.e. 93-95 percent of the calcium load was buffered by a process insensitive to FCCP. This FCCP- insensitive buffer system was not saturated by the largest calcium loads imposed, indicating a capacity of at least several millimolar. Treatment of previously loaded axons with FCCP or apyrase plus cyanide produced rises in ionized calcium which could be correlated with the extent of the load. Analysis of results indicated that, whereas only 6 percent of the endogenous calcium in fresh axons is stored in the FCCP-sensitive (presumably mitochondrial) buffer system, about 30 percent of an imposed exogenous load in the range of 50-2,500 μM is taken up by this system.     

Synthesis of epidermal growth factor receptor in human A431 cells. Glycosylation-dependent acquisition of ligand binding activity occurs post-translationally in the endoplasmic reticulum

It was previously demonstrated that the epidermal growth factor (EGF) receptor in human A431 cells undergoes a slow post-translational modification by which it acquires EGF binding capacity (Slieker, L.J., and Lane, M.D. (1985) J. Biol. Chem. 260, 687-690). In this report, the role of glycosylation in the acquisition of ligand binding activity and in the intracellular translocation of the receptor precursor is characterized. Human A431 cells were incubated with [35S]methionine, and 35S-labeled EGF receptors were purified either by immunoprecipitation (total receptor) or by adsorption to an EGF affinity matrix (high affinity, or active receptor). The half-time for receptor activation is approximately 30 min and precedes its acquisition of resistance to endo-beta-N-acetylglucosaminidase H (t 1/2 = 75 min), a medial Golgi event. Activation is blocked by tunicamycin and is markedly slowed (t 1/2 = 120 min) by 1-deoxynojirimycin, an inhibitor of glucosidase I. In the latter case, the oligosaccharide chains are not further processed to complex forms. Treatment of the active high mannose receptor with endo-beta-N-acetylglucosaminidase H generates a fully active aglycoreceptor polypeptide, indicating that core oligosaccharide addition is a prerequisite for activation but that oligosaccharide chains are not intrinsically required for EGF binding. Subcellular fractionation studies showed that the EGF receptor is activated in the endoplasmic reticulum and that translocation from that organelle is extremely slow (t 1/2 = 75 min). Since the latter translocation rate approximates that for the acquisition of the resistance to endoglycosidase H, transit from the endoplasmic reticulum appears to be rate-limiting for the maturation of the receptor. Both tunicamycin and 1-deoxynojirimycin inhibit exit from the endoplasmic reticulum in parallel with their effects on the acquisition of binding activity. Immunoprecipitation of 35S-labeled EGF receptor with antiphosphotyrosine antibody in the presence of ATP suggested that the autophosphorylation activity of the receptor is also acquired post-translationally. The possible correlation of this to EGF binding activity is discussed.     

安徽庐江鸭乙型肝炎病毒LJ-76转染细胞系的建立

为建立鸭乙型肝炎病毒ＬＪ－７６的转染细胞系,将ＬＪ－７６病毒ＤＮＡ插入到ｐＵＣ１９的ＥｃｏＲⅠ位点上,分离得到含有双拷贝ＬＪ－７６ＤＮＡ的重组质粒．通过磷酸钙沉淀方法,将经ＣｓＣｌ等密度离心纯化的ＬＪ－７６ＤＮＡ双体导入到人肝癌细胞ＢＥＬ７４０２中．收集转染细胞的培养液进行蔗糖密度梯度离心,所得沉淀经检测发现含有ＬＪ－７６ＤＮＡ并具有特异性ＤＨＢＶ内源性ＤＮＡ多聚酶活性;对上述样品通过ＤｏｔＥＩＡ检测ＤＨＢＶ核心抗原及表面抗原结果为阳性．Ｓｏｕｔｈｅｒｎｂｌｏｔ分析表明转染细胞内存在病毒ＤＮＡ复制中间体ｃｃｃＤＮＡ、ｓｓＤＮＡ和ｒｃＤＮＡ,而ｃｃｃＤＮＡ被认为是复制活动较为活跃的标志．电镜观察转染细胞的上清发现有病毒颗粒的存在．     

Diversity among bacteria isolated from the deep subsurface

Culturable bacteria from the deep subsurface (179 m) at Cerro Negro, New Mexico were isolated and characterized. The average number of viable aerobic bacteria was estimated to be 5×10⁵g^–1 of sediment, but only about 0.1% of these could be recovered on agar medium when incubated under aerobic conditions. Of 158 strains isolated from this depth, 92 were characterized by cellular fatty acid profiles (FAME), 36 by analysis of partial 16S rDNA sequences, and 44 by rep-PCR genome fingerprint analysis using three different sets of oligonucleotide primers (REP, BOX, or ERIC). These analyses showed the majority of isolates (67%) were Gram-positive bacteria and primarily members of genera with a high %G+C DNA. The remaining isolates were -subdivisionProteobacteria (19%) and members of the flavobacteria group (14%). The diversity indices based on these different methods of characterization were very high suggesting this subsurface habitat harbors a highly diverse microbial community.     

Post-translational processing of the epidermal growth factor receptor. Glycosylation-dependent acquisition of ligand-binding capacity

The post-translational processing of the epidermal growth factor receptor in human A431 epidermoid carcinoma cells has been investigated. By employing the affinity matrix epidermal growth factor Affi-Gel in conjunction with immunoprecipitation, it has been demonstrated that core oligosaccharide addition is essential for the acquisition of epidermal growth factor-binding activity. Furthermore, the initial 160-kDa translation product was observed to undergo a processing step by which ligand-binding activity was acquired with a half-time of approximately 30 min while exhibiting no apparent change in mobility on sodium dodecyl sulfate-polyacrylamide gels. This was shown not to involve the conversion of high-mannose chains to complex chains which have been capped with fucose and sialic acid. Possible explanations for this activation in terms of translocation of intermediates and/or formation of disulfide bonds are discussed.     

The evolution of antennal courtship in diplazontine parasitoid wasps (Hymenoptera,Ichneumonidae, Diplazontinae)

Background

As predicted by theory, traits associated with reproduction often evolve at a comparatively high speed. This is especially the case for courtship behaviour which plays a central role in reproductive isolation. On the other hand, courtship behavioural traits often involve morphological and behavioural adaptations in both sexes; this suggests that their evolution might be under severe constraints, for instance irreversibility of character loss. Here, we use a recently proposed method to retrieve data on a peculiar courtship behavioural trait, i.e. antennal coiling, for 56 species of diplazontine parasitoid wasps. On the basis of a well-resolved phylogeny, we reconstruct the evolutionary history of antennal coiling and associated morphological modifications to study the mode of evolution of this complex character system.

Results

Our study reveals a large variation in shape, location and ultra-structure of male-specific modifications on the antennae. As for antennal coiling, we find either single-coiling, double-coiling or the absence of coiling; each state is present in multiple genera. Using a model comparison approach, we show that the possession of antennal modifications is highly correlated with antennal coiling behaviour. Ancestral state reconstruction shows that both antennal modifications and antennal coiling are highly congruent with the molecular phylogeny, implying low levels of homoplasy and a comparatively low speed of evolution. Antennal coiling is lost on two independent occasions, and never reacquired. A zero rate of regaining antennal coiling is supported by maximum parsimony, maximum likelihood and Bayesian approaches.

Conclusions

Our study provides the first comparative evidence for a tight correlation between male-specific antennal modifications and the use of the antennae during courtship. Antennal coiling in Diplazontinae evolved at a comparatively low rate, and was never reacquired in any of the studied taxa. This suggests that the loss of antennal coiling is irreversible on the timescale examined here, and therefore that evolutionary constraints have greatly influenced the evolution of antennal courtship in this group of parasitoid wasps. Further studies are needed to ascertain whether the loss of antennal coiling is irreversible on larger timescales, and whether evolutionary constraints have influenced courtship behavioural traits in a similar way in other groups.