Paintable and Rapidly Bondable Conductive Hydrogels as Therapeutic Cardiac Patches

In recent years, cardiac patches have been developed for the treatment of myocardial infarction. However, the fixation approaches onto the tissue through suture or phototriggered reaction inevitably cause new tissue damage. Herein, a paintable hydrogel is constructed based on Fe³⁺ -triggered simultaneous polymerization of covalently linked pyrrole and dopamine in the hyperbranched chains where the in situ formed conductive polypyrrole also uniquely serves to crosslink network. This conductive and adhesive hydrogel can be conveniently painted as a patch onto the heart surface without adverse liquid leakage. The functional patch whose conductivity is equivalent to that of normal myocardium is strongly bonded to the beating heart within 4 weeks, accordingly efficiently boosting the transmission of electrophysiological signals. Eventually, the reconstruction of cardiac function and revascularization of the infarct myocardium are remarkably improved. The translatable suture-free strategy reported in this work is promising to address the human clinical challenges in cardiac tissue engineering.

Shotgun Glycomics Identifies Tumor-Associated Glycan Ligands Bound by an Ovarian Carcinoma-Specific Monoclonal Antibody

Cancers display distinctive carbohydrate molecules (glycans) on their surface proteins and lipids. mAb A4, an in-house generated monoclonal IgM antibody, is capable of distinguishing malignant ovarian carcinoma cells from benign ovarian epithelia by binding specifically to cancer cell-associated glycans. However, the structural details of the glycan targets of mAb A4 have been elusive. Here we developed a novel approach of isolating and fractionating glycan molecules released from glycoproteins in cancer cell lysates using HILIC-UPLC, and used them as probes on a microarray for affinity-based identification of the binding targets, allowing full-size, difficult to synthesize, cancer-associated glycans to be directly studied. As a result of this "shotgun" glycomics approach, we corroborate the previously assigned specificity of mAb A4 by showing that mAb A4 binds primarily to large (>15 glucose units), sialylated N-glycans containing the H-type 1 antigen (Fuc-α1,2-Gal-β1,3-GlcNAc). Although mAb A4 was also capable of directly binding to type 1 N-acetyl-lactosamine, this epitope was mostly shielded by sialylation and thus relatively inaccessible to binding. Knowledge of the structure of mAb A4 antigen will facilitate its clinical development as well as its use as a diagnostic biomarker.

Analysis of Models Predicting Morphology Transitions in Reactive Twin-Screw Extrusion of Bio-Based Polyester/Polyamide Blends

Immiscible PLA/PA11 of 80/20 and 50/50 wt% were compatibilized through addition of p-toluenesulfonic acid (TsOH) catalyst in reactive ultra-high speed twin-screw extrusion. Two mixing screw designs were compared for their ability to disperse the PA11 droplets in the PLA matrix as a function of screw speed up to 2000 rpm. The size and polydispersity of droplets of dispersed PA11 decreased when a high shear (HS) screw was used, whereas broad droplet size distribution was produced in the low shear (LS) screw. Two models predicting the droplet size dependence on shear rate, viscosity ratio and interfacial tension were fit to the experimental data. The Serpe model including volume fraction effects produced a better fit compared to the Wu model, which does not include volume fraction effects. Mechanical testing indicated that the compatibility of PLA/PA11 blends was improved through addition of TsOH catalyst for 50/50 wt% blends due to ester – amide exchange reactions at the interfaces in the immiscible PLA and PA11 phases. The enhancement of ductility was greater after processing with the LS screw configuration than the HS screw configuration. The inferior properties after high shear mixing were likely due to molecular weight degradation during processing. While the aggressive shear in the HS screw design resulted in fine dispersion, care should be taken to minimize degradation, especially for shear sensitive polymers.

A π-π conjugation-containing soft and conductive injectable polymer hydrogel highly efficiently rebuilds cardiac function after myocardial infarction

Previous studies suggested that a stiffer hydrogel system exhibited a better performance to promote heart function after myocardial infarction (MI). However, the nature of myocardium, a tissue that alternately contracts and relaxes with electrical impulses, leads us to hypothesize that a soft and conductive hydrogel may be in favor of mechanical and electrical signals transmission to enhance heart function after MI. In this work, π-π conjugation interaction was first employed to produce a soft injectable hydrogel with conductive property. Melamine with π-π conjugation ring was used as a core to synthesize a multi-armed crosslinker PEGDA700-Melamine (PEG-MEL), which could crosslink with thiol-modified hyaluronic acid (HA-SH) to form an injectable hydrogel rapidly. By incorporating graphene oxide (GO), the injectable PEG-MEL/HA-SH/GO hydrogel exhibited a soft (G' = 25 Pa) and anti-fatigue mechanical property and conductive property (G = 2.84 × 10^-4 S/cm). The hydrogel encapsulating adipose tissue-derived stromal cells (ADSCs) was injected into MI area of rats. The significant increase in α-Smooth Muscle Actin (α-SMA) and Connexin 43 (Cx43) expression confirmed that the gel efficiently promoted the transmission of mechanical and electrical signals. Meanwhile, a significant improvement of heart functions, such as distinct increase of ejection fraction (EF), smaller infarction size, less fibrosis area, and higher vessel density, was achieved.

Solvent-resistant polyetherimide network systems via phenylethynylphthalic anhydride endcapping

The synthesis and characterization of a highly processable thermosetting polyimide system based on 22'-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride or bisphenol A dianhydride (BPA-DA) endcapped with 4-phenylethynylphthalic anhydride is described. The system afforded oligomers that were readily melt processable at high curing temperatures (380-420 CC). Imide oligomers ranging from MR = 2000 to 40 000 g molI and copolyimides were synthesized using the ester acid of the dianhydrides and either meta- and/or para-phenylene diamines as comonomers via solution imidization techniques. The oligomers were shown to display low melt viscosity values and to flow under low pressure during compression moulding. The thermally cured polymers formed tough creasable films and displayed excellent solvent resistance which was correlated to their high gel fractions (>95%). Very significant increases in glass transition temperatures were observed after cure of a 3000., oligomer. The mera-phenylene diamine-based polymer exhibited a cured Ts approximately 30C lower (233C) than the para:meta (70:30) system (267C). The all para-phenylene diamine-based homopolymers could be completely cyclized in solution but crystallized at room temperature to produce fine insoluble powders. The resulting moderately semicrystalline homopolymer showed a TM of up to 321 'C which was not observed on the second heating. These polyimides also show excellent thermal stability as judged by thermogravimetric analysis (TGA) and are being examined as structural adhesives and matrix resins.

Discharge documentation improvement project: a pilot study

BACKGROUND

Discharge summaries remain a critical communication tool with primary care physicians. In a previous study of over 200 general medicine discharge summaries, we demonstrated that only 50% contain information regarding the indication and follow up required of any medicine changes on discharge.

AIM

In this follow up pilot study, we assess the role of feedback and token incentives in improving discharge documentation.

METHODS

Over a 14-week period, we randomly audited a selection of discharge summaries on a fortnightly basis. The results of these audits were fed back to the junior medical staff who compiled these summaries. If over 80% of the audited discharge summaries adequately documented the indication, with required follow up for new medication changes, junior doctors were provided with a token, non-monetary incentive for their efforts. At the end of the study period, we then conducted a survey of the junior doctors involved and collected feedback regarding their impressions of the study.

RESULTS

Over the study period, 722 discharge summaries were completed and eligible for analysis. Over this time, mean appropriate documentation regarding medicine indication improved by 32%, and follow-up documentation improved by 10%. Overall, the participants felt the interventions were beneficial and that they should be continued beyond the study period.

CONCLUSIONS

Education coupled with regular feedback and non-monetary incentives can potentially lead to improvements in the quality of discharge summaries.

Intraperitoneal Administration of Low Dose Aluminium in The Rat: How Good is It to Produce a Model for Alzheimer Disease

Since neurotoxicity of aluminium (Al) resembles the progressive neurodegeneration observed in Alzheimer Disease (AD), Al administration in several ways has been used to produce AD model. Intraperitoneal (ip) low dose (4.2 mg/ kg) Al injection in rats for long periods is the preferred method by some researchers. In this paper, the efficiency of this method for producing an AD model was evaluated. In this study, we looked at the neuropathology of Al and the characteristic lesions of AD by histological and immunohistochemical techniques and determined oxidative stress markers in the brains of Al-treated and control rats. We also made electrophysiological recordings at the hippocampus and evaluated possible behavioural changes by Morris water maze test. However, no pathologic changes occurred in the animals except for an impairment in long-term potentiation (LTP) in the hippocampus (e.g. the LTPs of population spike (PS) amplitude at 15 min post-tetanus were measured as 217±27% in Al-treated rats and as 240±42% in sham-treated rats, of baseline PS amplitude). According to the findings of the present study, low dose of ip Al in rats is not sufficient to produce a good AD model. Higher doses (≥10 mg/kg) should be used.