Outstanding Articles
ICG clearance test based on photoacoustic imaging for assessment of human liver function reserve: An initial clinical study

Liver function reserve (LFR) plays an extensive and important role in patients with liver disease. Indocyanine green (ICG) clearance test is the standard diagnostic approach for LFR evaluation which was performed by spectrophotometry or pulse dye densitometry (PDD). Spectrophotometry is the gold standard, it's invasive and not real-time. PDD is non-invasive, but accuracy of PDD is controversial. Taken spectrophotometry as the reference standard, this study investigated the accuracy of photoacoustic imaging (PAI) method for LFR assessment and compared to PDD in healthy volunteers. The results demonstrated a strong correlation between PAI method and spectrophotometry (r = 0.9649, p < 0.0001). No significant difference was shown in ICG clearance between PAI and spectrophotometry method (rate constant k1 vs. k2, 0.001158 +−0.00042 vs. 0.001491 +- 0.00045, p = 0.0727; half-life t1 vs. t2, 601.2 s vs. 474.4 s, p = 0.1450). These results indicated that PAI may be valuable as a noninvasive, accurate diagnostic tool for LFR assessment in human.

2023-05-31

Photoacoustics

West China Hospital, Sichuan University

Structural basis of BAM-mediated outer membrane β-barrel protein assembly

The outer membrane structure is common in Gram-negative bacteria, mitochondria and chloroplasts, and contains outer membrane β-barrel proteins (OMPs) that are essential interchange portals of materials1,2,3. All known OMPs share the antiparallel β-strand topology4, implicating a common evolutionary origin and conserved folding mechanism. Models have been proposed for bacterial β-barrel assembly machinery (BAM) to initiate OMP folding5,6; however, mechanisms by which BAM proceeds to complete OMP assembly remain unclear. Here we report intermediate structures of BAM assembling an OMP substrate, EspP, demonstrating sequential conformational dynamics of BAM during the late stages of OMP assembly, which is further supported by molecular dynamics simulations. Mutagenic in vitro and in vivo assembly assays reveal functional residues of BamA and EspP for barrel hybridization, closure and release. Our work provides novel insights into the common mechanism of OMP assembly.

2023-04-30

Nature

West China Hospital, Sichuan University

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Accelerated bone defect regeneration through sequential activation of the M1 and M2 phenotypes of macrophages by a composite BMP-2@SIS hydrogel: An immunomodulatory perspective

The immune response of the host towards foreign body, especially in the form of giant cell reaction against the implanted materials, is a vital factor for determining the repair outcome of bone defect. Biomaterials with good immunomodulatory capacity and suitable degradation may promote the regeneration of bone defect and osteointegration with the host. Small intestine submucosa (SIS), a decellularized material, has been shown to possess a property for inducing the M2 phenotype of macrophages. Our findings suggested that the SIS hydrogel could induce the macrophages to polarize into mixed M1/M2 phenotypes, and such phenotypes have enhanced the migration and tube formation of angiogenesis-associated cells in vitro, whilst having a mild effect on osteoclastogenesis and osteogenesis. Experiment with a rat model for critical-sized bone defect regeneration further demonstrated that the composite BMP-2@SIS hydrogel could sequentially activate M1 and M2 macrophages and promote early-stage angiogenesis, which altogether expedited final bone defect regeneration.

2022-08-31

Composites Part B: Engineering

West China Hospital, Sichuan University