Characteristics of fundus autofluorescence imaging at 795 nm and its correlations with postoperative outcomes for idiopathic macular hole.

BACKGROUND: Vitrectomy combined with internal limiting membrane (ILM) peeling or ILM inverted flap greatly improves hole closure and vision prognosis for idiopathic macular holes (IMH). The application of indocyanine green (ICG) in MH surgery increases the visibility of ILM and the safety of surgery. However, the area of ILM peeling and the state of the flap and a closed hole has not been well observed. AIM: Fundus autofluorescence at 7935nm can show the range of ILM peeling and the state of the hole site and ILM flap by monitoring residual ICG postoperatively. However, the characteristics of fundus autofluorescence especially the site of the closed hole, and its relationship with vision prognosis have not been explored. The aim of this project was to find the autofluorescence features of the closed hole and their relation with vision. OBJECTIVE: To investigate the characteristics of fundus autofluorescence imaging after ICG-assisted vitrectomy for IMH and to evaluate the correlations of fluorescence patterns at the MH site with visual acuity and macular anatomic outcomes. METHODS: We retrospectively evaluated 33 IMH patients (33 eyes) who underwent a 25G pars plana vitrectomy (follow-up, 6-14.5 months). ICG staining (2.5 mg/mL) was either used to remove the internal limiting membrane (ILM) or the inverted ILM flap was overlaid on the hole. After surgery, fluorescence imaging of the fundus was obtained using a scanning laser ophthalmoscope at 795 nm. RESULTS: On fluorescence imaging, the area of ILM peeling in all eyes showed hypofluorescence with no changes over time. The inverted ILM flap (performed in 18 eyes) was positioned on the inferior retina and exhibited early mild hyperfluorescence with blurred edges. This was gradually enhanced up to 3-6 months postoperatively and was then attenuated. MHs showed two distinct patterns on optical coherence tomography: granular (21 eyes) and patchy hyperfluorescence (12 eyes). Best-corrected visual acuity improved postoperatively in all cases (p<0.001, Z=-4.744). VA was worse in the patchy (vs. granular) hyperfluorescence cases (p=0.011, Z=-2.548). CONCLUSION: The status of the ILM peeling area, ILM flap, and closed MH can be clearly observed using autofluorescence imaging at 795 nm. Fluorescence may be due to ICG staining of the ILM and accumulation in retinal pigment epithelium cells during ICG-assisted surgery. Granular hyperfluorescence at the MH site may indicate good anatomic and visual prognoses.

Rational modification of hydroxy-functionalized covalent organic frameworks for enhanced photocatalytic hydrogen peroxide evolution.

Covalent organic frameworks (COFs), a class of flexibly tunable crystalline materials, have fascinating potential in photocatalytic hydrogen peroxide (H2O2) evolution under visible light irradiation. However, achieving efficient catalytic activity by tuning the composition of COFs and the linkages of building blocks is still a challenge. Herein, four imine-linked COFs with different numbers of hydroxy-functionalized are constructed to unveil the latent structure-activity relationship between the reversibility of bonding in supramolecular chemistry and the photocatalytic H2O2 performance. As the optimized material, TAPT-HTA-COF (1H-COF) containing single hydroxy group in aldehyde node exhibits a highest ordered structure and conjugation degree along and across the plane in the extended frameworks originating from the flexibly reversible iminol-to-ketoenamine tautomerism than others, which broadens the visible light absorption and accelerates the dissociation of photogenerated carriers in 1H-COF. These merits ensure that 1H-COF has the highest H2O2 yield (44.5 µmol L-1) and O2 two-electron reduction pathway among the four COFs under visible light irradiation (λ > 420 nm, 10 vol% isopropanol aqueous solution). At the same time, the long-range ordered framework of 1H-COF is well preserved during the photocatalytic H2O2 evolution process assisted by the proton-induced tautomerization. This work facilitates the design and development of COF-based photocatalysts in the evolution of H2O2.

A highly xyloglucan active lytic polysaccharide monooxygenase EpLPMO9A from Eupenicillium parvum 4-14 shows boosting effect on hydrolysis of complex lignocellulosic substrates.

The recently identified lytic polysaccharide monooxygenases (LPMOs) are important auxiliary proteins which contribute to lignocellulose biodegradation by oxidatively cleaving the glycosidic bonds in cellulose and other polysaccharides. The vast differences in terms of substrate specificity and regioselectivity within LPMOs provide us new possibilities to find promising candidates for the use in enzyme cocktails in biorefinery applications. In this study, a highly xyloglucan active family AA9 lytic polysaccharide monooxygenase EpLPMO9A was identified from Eupenicillium parvum 4-14. EpLPMO9A exhibited a mixed C1/C4 oxidative cleavage activity on cellulose and xyloglucan with a broad range of pH stability and good thermal stability at 40 °C. It showed a higher boosting effect on the enzymatic saccharification of complex lignocellulosic substrates associated with xyloglucan than on the lignocellulosic substrates without xyloglucan particularly in low commercial cellulase dosage cases. The oxidative cleavage of xyloglucan by EpLPMO9A may facilitate to open up the sterical hindrance of cellulose by xyloglucan and thereby increase accessibility for cellulase to lignocellulosic substrates. The discovery of more and more hemicellulose-active LPMOs and their contribution to breaking down the barriers by oxidatively acting on hemicellulose may expand our knowledge for their functions of LPMOs in lignocellulose biodegradation.

Characterization of Two New Endo-ß-1,4-xylanases from Eupenicillium parvum 4-14 and Their Applications for Production of Feruloylated Oligosaccharides.

Two new endo-1,4-beta-xylanases encoding genes EpXyn1 and EpXyn3 were isolated from mesophilic fungus Eupenicillium parvum 4-14. Based on analysis of catalytic domain and phylogenetic trees, the xylanases EpXYN1 (404 aa) and EpXYN3 (220 aa) belong to glycoside hydrolase (GH) family 10 and 11, respectively. Both EpXYN1 and EpXYN3 were successfully expressed in Pichia pastoris and the recombinant enzymes were characterized using beechwood xylan, birchwood xylan, or oat spelt xylan as substrates, respectively. The optimum temperatures and pH values were 75 °C and 5.5 for EpXYN1, and 55 °C and 5.0 for EpXYN3. EpXYN1 exhibited a high stability at high temperature (65 °C) or at pH values from 8 to 10. EpXYN3 kept over 80% enzymatic activity after treatment at pH values from 3 to 10. The specific activities of EpXYN1 and EpXYN3 were 384.42 and 214.20 U/mg using beechwood xylan as substrate, respectively. EpXYN1 showed lower Km values and higher specific activities toward different xylans compared to EpXYN3. Thin-layer chromatography analysis indicated that the hydrolysis profiles of xylans or xylo-oligosacharides were different by EpXYN1and EpXYN3. EpXYN3 had a higher efficiency than EpXYN1 in production of feruloylated oligosaccharides (FOs) from de-starched wheat bran. The maximum levels of FOs released by EpXYN1 and EpXYN3 were 11.1 and 14.4 µmol/g, respectively. In conclusion, the two xylanases are potential candidates for various industrial applications.

Highly efficient transformation of a (hemi-)cellulases-producing fungus Eupenicillium parvum 4-14 by Agrobacterium tumefaciens.

The mesophilic fungus Eupenicillium parvum 4-14 is an important producer of thermotolerant hemicellulolytic and cellulolytic enzymes. The aim of this study was to establish a method for genetic manipulation of the fungus by Agrobacterium tumefaciens. The promotor PgpdA of a glyceraldehyde-3-phosphate dehydrogenase gene was isolated from E. parvum 4-14. To transform the fungus, an expression plasmid containing a superfolder green fluorescent protein (sfGFP) gene under the control of PgpdA promotor was constructed using the plasmid pAg1-H3 as a parental plasmid. Using the fungal ascospores as receptor and hygromycin B resistance as a selection marker, the recombinant plasmid was successfully introduced into the fungal cells by A. tumefaciens-mediated transformation (ATMT) method. Acetosyringone (AS) was essential to the successful transformation. The transformation frequency was significantly affected by the co-culture temperature and time, the quantity of fungal spores and the AS concentration. The highest transformation frequency was up to 373 transformants per 105 fungal spores, which was higher than those of other fungal species. The fungal transformants were genetically stable after five subcultures in the absence of antibiotic. GFP protein was strongly expressed in the hypha of fungal transformants. In conclusion, the ATMT is a highly efficient method for genetic manipulation of E. parvum 4-14, and will improve the molecular researches on the fungus.