RESUMEN
Various genetic switches have been developed to let engineered cells perform designed functions. However, a sustained input is often needed to maintain the on/off state, which is energy-consuming and sensitive to perturbation. Therefore, we developed a set of transcriptional switches for cell states control that were constructed by the inversion effect of site-specific recombinases on terminators. Such a switch could respond to a pulse signal and maintain the new state by itself until the next input. With a bottom-up design principle, we first characterized the terminators and recombinases. Then the mutual interference was studied to select compatible pairs, which were used to achieve one-time and two-time state transitions. Finally, we constructed a biological seven-segment display as a demonstration to prove such switch's immense potential for application.
Asunto(s)
Recombinasas , MetabolismoRESUMEN
ObjectiveStudy the relationship among CaSR expression, tubulointerstitial damage,metabolic disturbance of calcium and phosphorus and microvascular density around the tubulointerstitium in children with steroid-resistant nephrotic syndrome.Methods36 cases of children with primary nephrotic syndrome were divided into hormone-sensitive group and steroid-resistant group.Semi-quantitative scores for tubulointerstitial pathological evaluation of the extent of damage, automatic biochemical analyzer for the determination of serum calcium (Ca), phosphorus (P) concentration of renal tubular epithelial CaSR expression and microvessel microvascular density around the tubulointerstitium were determined by immunohistochemical assay.ResultsMore severe the tubulointerstitial damage, lower level of serum Ca and higher level of serum P were observed [(2.26 ± 0.15) mmol/L]in children of the steroid-resistant group and the steroid-sensitive group [(1.90 + 0.12) mmol/L, P ＜ 0.05].CaSR expression (4.63 + 0.78) of renal tubular epithelial cells in the steroid- sensitive group was significantly lower than that in the steroid-resistant group (6.56 + 1.22, P ＜ 0.05), but microvascular density was significantly higher in the steroid- sensitive group(2.98 +0.35 vs 2.02 +0.24, P ＜0.05).When the tubulointerstitial damage was mild, CaSR expression (4.15 +0.58) in renal tubular epithelial cells in the steroid- sensitive group (4.26 ±0.61) was lower than the steroid-resistant group(3.12 ± 0.33; 3.01 ± 0.21), and microvascular density was higher,but the difference was not significant(P ＞0.05).In the moderate tubulointerstitial damage, CaSR expression in renal tubular epithelial cells in the steroid- sensitive group (5.35 ± 0.64) was significantly lower than the resistant group (7.37 +0.81, P ＜0.01), and microvascular density was significantly higher than the resistant group (2.81 ±0.16, 2.02 ±0.14, P ＜0.05).Compared by mild and moderate tubulointerstitial damage in children with the steroid-resistant, CaSR expression (11.46 ± 1.38) in children with severe tubulointerstitial damage was significantly increased, and microvascular density (1.15 ± 0.11) was significantly decreased (all P ＜ 0.01).ConclusionsCaSR expression was increased and microvascular density around the tubulointerstitium was decreased in children with steroid-resistant nephrotic syndrome.Dut to steroid resistance, the cytotoxic of steroid damaged the renal tubular epithelial cells, the metabolic disturbance of calcium and phosphorus and the damage of blood vessel endothelium finally resulted in severe tubulointerstitial damage.