Protein-polymer conjugates for forming photopolymerizable biomimetic hydrogels for tissue engineering

Collagen, fibrin and albumin are popular proteins for making biological scaffolds for tissue engineering because of their biocompatibility, biodegradability, and availability. A major drawback of biological protein-based biomaterials is the limited control over their physical and biodegradation properties. Our laboratory has been developing new protein-based biomaterials with tunable properties without the use of cytotoxic protein cross-linking techniques. We describe the formation and assembly of photopolymerizable biomimetic hydrogel scaffolds made from protein-polymer conjugates of poly(ethylene glycol) (PEG) and collagen, fibrin or albumin. The conjugation of PEG to these proteins (PEGylation) was verified by SDS-PAGE and the polymerization reaction into a hydrogel network was confirmed by shear rheometry. The differences in rheology and swelling characteristics of the three hydrogel materials underscore the importance of the molecular relationship between the PEG and the protein constituent in this protein-polymer arrangement. The biofunctionality of the PEGylated collagen and fibrinogen hydrogels sustained both cell adhesion and proteolytic degradation that enabled 3-D cell spreading and migration within the hydrogel network. PEG-albumin hydrogels exhibited poor cell spreading and migration by virtue of the fact that the albumin backbone lacks any known cell adhesion sites. Despite differences in the biological and structural composition of the PEGylated fibrinogen and collagen hydrogels, the rate of cellular migration within each material was not significantly different.     

Empirical antibiotics against Gram-positive infections for febrile neutropenia: systematic review and meta-analysis of randomized controlled trials

OBJECTIVES: To assess the value of empirical anti-Gram-positive antibiotics for the treatment of febrile neutropenia. METHODS: Systematic review and meta-analysis of randomized controlled trials comparing antibiotics with anti-Gram-positive spectrum to control or placebo, in addition to the same baseline antibiotic regimen in both arms. We searched MEDLINE, EMBASE, LILACS, the Cochrane Library, conference proceedings, and references. No restrictions on inclusion were imposed. Two reviewers independently applied selection criteria, carried out quality assessment, and extracted the data. Relative risks with 95% confidence intervals were pooled using the fixed effect model. The primary outcome assessed was all-cause mortality. RESULTS: Thirteen studies met inclusion criteria, including 2392 participants. Glycopeptides were assessed in nine trials. Empirical anti-Gram-positive antibiotics were assessed for the initial treatment in 11 studies, and for persistent fever in two. No significant difference in all-cause mortality was seen [RR 0.86 (0.58-1.26), seven studies, 852 participants]. Overall failure at end of therapy occurred equally [RR 1.00 (0.79-1.27), six studies, 943 participants]. Failure associated with treatment modifications was more frequent in the control arm when empirical initial glycopeptides were assessed [RR 0.70 (0.61-0.80), five studies, 1178 participants]. Bacterial superinfections, mainly Gram-positive, were detected less frequently in the intervention arm. Adverse events were significantly more common with the additional antibiotic, and nephrotoxicity was significantly more common with additional glycopeptides [RR 1.88 (1.10-3.22), six studies, 1282 participants]. No significant heterogeneity was present in these comparisons. CONCLUSIONS: The use of glycopeptides can be safely deferred until the documentation of a resistant Gram-positive infection.     

Hope for male fecundity: clinically insignificant changes in semen parameters over 10 years at a single clinic while assessing an infertility population

Journal of Assisted Reproduction and Genetics - What is the trend in sperm parameters in a group of men attending a single reproductive center, over a 10-year period? A retrospective study was...     

PNist: interactive volumetric measurements of plexiform neurofibromas in MRI scans

Purpose

Volumetric measurements of plexiform neurofibromas (PNs) are time consuming and error prone, as they require the delineation of the PN boundaries, which is mostly impractical in the daily clinical setup. Accurate volumetric measurements are seldom performed for these tumors mainly due to their great dispersion, size and multiple locations. This paper presents a semiautomatic method for segmentation of PN from STIR MRI scans.

Methods

Plexiform neurofibroma interactive segmentation tool (PNist) is a new tool to segment PNs in STIR MRI scans. The method is based on histogram tumor models computed from a training set.

Results

Experimental results from 28 datasets show an average absolute volume difference of 6.8 % with an average user time of approximately 7 min versus more than 13 min with manual delineation. In complex cases, the PNist user time is less than half in compared to state-of-the-art tools.

Conclusions

PNist is a new method for the semiautomatic segmentation of PN lesions. Its simplicity and reliability make it unique among other state-of-the-art methods. It has the potential to become a clinical tool that allows the reliable evaluation of PN burden and progression.     

ER homeostasis and motility of NSCLC cell lines can be therapeutically targeted with combined Hsp90 and HDAC inhibitors

Background and objectiveLung cancer remains the most common cause of cancer-related death in the world for which novel systemic treatments are urgently needed.Protein homeostasis that regulates protein levels and their fold is critical for cancer cell proliferation and survival. A complex network of cellular organelles and signaling cascades is involved in control of protein homeostasis including endoplasmic reticulum (ER). Thus, proteins in control of ER homeostasis are increasingly recognized as potential therapeutic targets.Molecular chaperone heat shock protein 90 (Hsp90) and histone deacetylase (HDAC) play an important role in ER homeostasis. Previous studies demonstrate that Hsp90 and HDAC inhibitors are individually functional against lung cancer. In this work we suggested that combined Hsp90 and HDAC inhibitors may elevate ER stress thereby enhancing the anti non small lung cancer (NSCLC) activity.Methods and resultsUsing an in vitro cell line model we demonstrated that 17-DMAG (HSP90 inhibitor) co-administration with PTACH (HDAC inhibitor) caused elevated ER stress (immunoblotting) (more than 110%↑, p < 0.05) accompanied by apoptotic cell death (Annexin V) (7–21%↑, p < 0.05). Moreover, 17-DMAG/PTACH treated cells lost the ability to migrate (scratch test) (57–85%↓ of scratch closure, p < 0.05).ConclusionsOur findings provide proof-of-concept that targeting ER homeostasis is therapeutically beneficial in lung cancer cell lines. Indeed, the elevated ER stress caused by 17-DMAG/PTACH combined treatment leads to increased cell death of NSCLC cell lines compared to the application of the drugs separately.