Comparison of uniform resampling and nonuniform sampling direct-reconstruction methods in k-space for FD-OCT

The nonuniform distribution of interference spectrum in wavenumber k-space is a key issue to limit the imaging quality of Fourier-domain optical coherence tomography(FD-OCT).At present,the reconstruction quality at different depths among a variety of processing methods in k-space is still uncertain.Using simulated and experimental interference spectra at different depths,the effects of common six processing methods including uniform resampling(linear interpolation(LI),cubic spline interpolation(CSI),time-domain interpolation(TDI),and K-B window convolution)and nonuniform sampling direct-reconstruction(Lomb periodogram(LP)and nonuniform discrete Fourier transform(NDFT))on the reconstruction quality of FD-OCT were quantitatively analyzed and compared in this work.The results obtained by using simulated and experimental data were coincident.From the experimental results,the averaged peak intensity,axial resolution,and signal-to-noise ratio(SNR)of NDFT at depth from 0.5 to 3.0mm were improved by about 1.9 dB,1.4 times,and 11.8 dB,respectively,compared to the averaged indices of all the uniform resampling methods at all depths.Similarly,the improvements of the above three indices of LP were 2.0 dB,1.4 times,and 11.7 dB,respectively.The analysis method and the results obtained in this work are helpful to select an appropriate processing method in k-space,so as to improve the imaging quality of FD-OCT.

Identification of a hotspot on PD-L1 for pH-dependent binding by monoclonal antibodies for tumor therapy

Dear Editor,Monoclonal antibody(mAb)-based tumor immune checkpoint therapy(ICT)has gained particular interest in recent years.1 The molecular basis of binding between mAbs and PD-1 or PD-L1 has been reported,providing clear information of the binding“hotspots”for mAbs.2,3 Tumor suppression efficacy of PD-L1 specific mAbs relies on not only the blocking of PD-1/PD-L1 interaction to restore T cell reactivity,but also Fc-mediated tumor cell cytotoxity.PD-L1 antibody drug conjugate(ADC)for selective chemo-guided immune modulation of tumor has also been developed which has shown promising tumor suppression potency.4 MAbs that could bind to antigen in a pH-dependent manner would improve recycling of the antibodies and engineered IL-6R mAbs with pH-dependent binding properties have displayed increased lysosomal delivery and therapeutic potency.5 However,no PD-L1 specific mAb with pH-dependent binding property has been reported,and whether the binding to a specific region on PD-L1 would induce pH-dependent interaction remains unknown.