Hydrophilic, Porous, Fiber-Reinforced Collagen-Based Membrane for Corneal Repair.

Collagen membrane with outstanding biocompatibility exhibits immense potential in the field of corneal repair and reconstruction, but the poor mechanical properties limit its clinical application. Polycaprolactone (PCL) is a biodegradable polymer widely explored for application in corneal reconstruction due to its excellent mechanical properties, biocompatibility, easy processability, and flexibility. In this study, a PCL/collagen composite membrane with reinforced mechanical properties is developed. The membrane has a strong composite structure with collagen by utilizing a porous and hydrophilic PCL scaffold, maintaining its integrity even after immersion. The suture retention and mechanical tests demonstrate that compared with the pure collagen membrane, the prepared membrane has a greater tensile strength and twice the modulus of elasticity. Further, the suture retention strength is improved by almost two times. In addition, the membrane remains fully intact on the implant bed in an in vitro corneal defect model. Moreover, the membrane can be tightly sutured to a rabbit corneal defect, progressively achieve epithelialization, and remain unchanged during observation. Overall, the PCL/collagen composite membrane is a promising candidate as a suturable corneal restoration material in clinical keratoplasty.

Cefotaxime-agar medium for laboratory detection of extended-spectrum and AmpC ?-lactamases in Enterobacteriaceae / 中华检验医学杂志

Objective To develop an easy,rapid and reproducible cefotaxime-agar medium(CTX- AM)for phenotypic detection of extended-spectrum ?-lactamases(ESBLs)and AmpC ?-lactamases (AmpCs)in Enterobacteriaceae.Methods The surface of a cefotaxime(CTX,0.5 ?g/ml)-Mueller- Hinton agar and ceftizoxime(CAZ,1 ?g/ml)-Mueller-Hinton agar plate was inoculated with a lawn of E. coli ATCC 25922 according to the standard disk diffusion method,respectively.Immediately prior to use.blank and clavulanic acid(10 ?g),cloxacillin(300 ?g),clavulanic acid/cloxacillin(10/300 ?g) disk were rehydrated with 10 ?l of saline and several colonies of each test organism were applied to disks. Then the results of CTX-AM method to interpret based on a zone of growth around the periphery of disks.A total 58 of ESBL and AmpC producing and non-producing isolates of Enterobacteriaceae,as identified by the double-disk enhancement test(DDET)and the three-dimensional extract method(TDEM).were used to evaluate the CTX-AM method.Positive control(E.cloacae 029M,K.pneumoniae ATCC 700603)and negative control(E.coli ATCC 25922)strains were included.Results The results of CTX-AM method were similar to the DDET and TDEM method for detecting ESBLs and AmpC production in Enterobacteriaceae,respectively.But inhibitor-resistant ?-lactamase(IR-BLs)and other ?-lactamases were not detected by DDET method.Conclusions The new method described here allows for testing of ESBL and AmpCs on a single plate.It is easy to perform and interpret,and also cost-effective,clinical laboratories may use this technique routinely to detect the oresence of ESBL and AmoCs.