Metallothioneins are low-molecular-weight, Cys-rich proteins that are ubiquitous in eukaryotic organisms. Since their first description as cadmium-and zinc-binding proteins in horse kidneys, metallothionein genes and proteins have been characterized from many different organisms (reviewed by Hamer, 1986;Robinson et al., 1993). In the plant kingdom, a few metallothionein-like genes have been characterized recently, including those from peas (Evans et al., 1990), maize (De Framond, 1991), Arabidopsis (Zhou and Goldsbrough, 1994, 1995), and Sambucus nigra (Coupe et al., 1995).Because of the nature of its metal-binding activity and induction by heavy metal ions, metallothionein is strongly believed to have a role in metal metabolism or detoxification (Hamer, 1986). However, some plant metallothioneinlike genes are not stimulated by heavy metal (De Miranda et al., 1990;Kawashima et al., 1992). In recent studies with cloned Brassica and Sambucus metallothionein-like genes, the accumulation of their mRNAs in the senesced leaflet
This study aimed to compare respiratory variation in transthoracic echo-derived aortic blood flow velocity (∆Vpeak) and inferior vena cava diameter (∆IVCD) with central venous pressure (CVP) as predictors of fluid responsiveness in children after repair of ventricular septal defect (VSD). A prospective study conducted in pediatric intensive care unit investigated 21 mechanically ventilated children who had undergone repair of VSD. Standardized volume replacement (VR) was the intervention used. Hemodynamic measurements including CVP, heart rate, mean arterial pressure, transthoracic echo-derived stroke volume (SV), cardiac output, ∆Vpeak, and ∆IVCD were performed 1 h after patient arrival in the intensive care unit. Hemodynamic measurements were repeated 10 min after VR by an infusion of 6% hydroxyethyl starch 130/0.4 (10 ml/kg) over 20 min. The volume-induced increase in the SV was 15% or more in 11 patients (responders) and less than 15% in 10 patients (nonresponders). Before volume replacement, the ∆Vpeak (23.1 ± 5.7% vs. 14.0 ± 7.7%; p = 0.006) and ∆IVCD (26.5 ± 16.2% vs. 9.2 ± 9.1%; p = 0.008) was higher in the responders than in the nonresponders, whereas CVP did not significantly differ between the two groups. The prediction of fluid responsiveness was higher with the ΔVpeak, as shown by a receiver operating characteristic curve area of 0.83 (95% confidence interval [CI], 0.61-1.00; p = 0.01), a ΔIVCD of 0.85 (95% CI, 0.69-1.00; p = 0.01), and a CVP of 0.48 (95% CI, 0.22-0.73; nonsignificant difference). The ∆Vpeak and ∆IVCD measured by transthoracic echocardiography can predict the response of SV after volume expansion in mechanically ventilated children at completion of VSD repair.
Three full length 1-aminocyclopropane-1-carboxylate (ACC) oxidase cDNA clones (pNG-ACO1, 1,254 bp; pNG-ACO2, 1,198 bp; and pNG-ACO3, 1,053 bp) were isolated from the TMV-treated leaf cDNA library of Nicotiana glutinosa plant. They share a high degree of sequence identity (78-81%) throughout the coding regions but are divergent within the 3'-untranslated regions. The gene-specific probes were prepared using these regions to investigate the differential expression of the ACC oxidase gene family in various organs and in response to a multitude of biotic and abiotic stresses in N. glutinosa plants. All three genes were transcriptionally active displaying unique patterns of expression. Both the pNG-ACO1 and pNG-ACO3 transcripts highly accumulated during the senescence of leaves, while the pNG-ACO2 mRNA was constitutively present. In addition, the NG-ACO1 and NG-ACO3 transcripts were predominantly found in roots whereas the NG-ACO2 mRNA was mainly in stems. Upon TMV infection, both NG-ACO1 and NG-ACO3 were markedly induced, but in mock treatment which has an effect of mild wounding, only the NG-ACO3 gene was induced. Furthermore, salicylic acid and CuSO4 treatments of leaves increased the level of NG-ACO1 and NG-ACO3 transcripts, while they did not affect the NG-ACO2 gene expression. Results showed that both the NG-ACO1 and NG-ACO3 genes were highly inducible by ethylene and methyl jasmonate treatments, with NG-ACO3 being more responsive. By contrast, NG-ACO2 did not respond to these growth regulators. Thus, it appears that there are two groups of ACC oxidase transcripts expressed in leaf tissue of N. glutinosa, either stress-induced or constitutive. The possible molecular mechanism of differential regulation of ACC oxidase gene expression and its physiological significance are discussed.
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