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Oral propranolol is the first-line therapy for infantile hemangioma (IH), but its mechanism of action remains unclear. The aim of this study was to evaluate the change in serum vascular endothelial growth factor (VEGF) levels in patients with IH who underwent propranolol treatment. The study included 22 patients with IH receiving propranolol treatment. At three time points-before treatment and 1 and 3 months after treatment-blood samples were examined by enzyme-linked immunosorbent assay for serum VEGF expression. The mean serum VEGF concentration in children with proliferative hemangiomas was 395.0 ± 176.7 pg/mL, approximately twice as high as in patients with venous malformations (mean 170.7 pg/mL) and in healthy controls (204.8 pg/mL, p = 0.006). After 1 month of propranolol treatment, the level had fallen 21.6% (p = 0.003), although the downward trend was less obvious after 3 months of treatment (18.0%, p = 0.63). VEGF expression correlated significantly with the lesion size (correlation coefficient [R] = 0.43, p = 0.046), whereas no correlation was observed with age (R = 0.13, p = 0.56). Serum VEGF levels were higher in patients with IH and fell after 1 month of oral propranolol treatment. Similar results, although less pronounced, were found after 3 months of treatment. Lesion volume and serum level of VEGF were significantly correlated.

Due to the voltage mismatch between the phase legs and the DC bus in Modular Multilevel Converters (MMCs), the differential current in MMCs is inherently subjected to circulating even order harmonics. Repetitive control based active harmonic suppression methods can be adopted to eliminate such harmonics. Nevertheless, conventional repetitive controllers have a relatively slow dynamic response because all the sampled errors in the past one cycle have to be stored, which causes a response delay for one fundamental period. This paper proposes an improved repetitive control scheme that exclusively copes with even order harmonics based on the circulating current characteristics of MMC systems. The design details of the even harmonic repetitive control scheme according to the harmonics characteristics are provided. The proposed even-harmonic repetitive control scheme requires halved data memory to store error samplings and the delay introduced by the repetitive controller is also reduced. According to the frequency domain analysis, the even-harmonic repetitive control features faster convergence rate, greater low-frequency gains, higher crossover frequency, and higher tolerance against system frequency deviation, while possessing the same even-order harmonics suppression capability and stability as conventional ones. Simulation and experimental results are presented to show the steady-state harmonics suppression capability, dynamic response, and disturbance tolerance of the proposed even-harmonic repetitive control scheme.

SummaryHepatic allograft rejection remains a challenging problem, with acute rejection episode as the major barrier for long-term survival in liver transplant recipients. To explore a strategy to prevent allograft rejection, we hypothesized that mesenchymal stem cells (