Agarose oligosaccharide- silver nanoparticle- antimicrobial peptide- composite for wound dressing

Marine polysaccharides or oligosaccharides have potential to promote wound healing due to their biocompatibility and physicochemical properties. However, microbial infection delays wound healing process, and novel antimicrobial wound dressings are urgently needed. Here, agarose oligosaccharides (AGO) obtained from marine red algae were used as a reducing and stabilizer for green synthesis of silver nanoparticles (AgNPs), and further successfully connected with odorranain A (OA), one of antimicrobial peptides (AMPs), to obtain a novel composite nanomaterial (AGO-AgNPs-OA). Transmission electron microscopy (TEM) and Malvern particle size analyzer showed that AGO-AgNPs-OA was spherical or elliptic with average size of about 100 nm. Circular dichroism (CD) spectroscopy showed that AGO-AgNPs stabilized the α-helical structure of OA. AGO-AgNPs-OA showed stronger anti-bacterial activities than AGO-AgNPs, and had good biocompatibility and significant promoting effect on wound healing. Our data suggest that AMPs conjugated marine oligosaccharides and AgNPs may be effective and safe antibacterial materials for wound therapy.

Cyclodextrin functionalized agarose gel with low gelling temperature for controlled drug delivery systems

Conventional agaroses with high gelling temperature are limited to apply to the field of drug delivery. In this study, β-cyclodextrin (βCD) functionalized agarose (CFA) with low gelling temperature was successfully prepared from ethylenediamine-functionalized agarose using mono-succinyl βCD. The gelling temperature of CFA dramatically decreased to 26.7 °C from 65 °C and the melting temperature declined from 95 °C to 66.1 °C. Upon drug loading, CFA can be used at 30 °C because of its low gelling temperature compared to agarose. CFA gel could be used both for bovine serum albumin as a full release, and for the doxorubicin (DOX) for sustained release, via inclusion complexation of βCD. Furthermore, cytotoxicity tests revealed that CFA was noncytotoxic. DOX in the CFA gel could retain the anti-cancer activity. Newly synthesized CFA with low gelling temperature offer a new means for the development of hydrogel-based delivery systems for a variety of therapeutic drugs.

Septal innervation regulates the function of α7 nicotinic receptors in CA1 hippocampal interneurons

The hippocampus receives substantial input from the medial septum/diagonal band of broca (MS/DB) via the fibria-fornix (FF). Projections from the MS/DB innervate hippocampal interneurons that express alpha7 nicotinic receptors and regulate excitation in principal cell populations. In the present report we used stereotaxic surgery, whole-cell patch clamping, and immunohistochemical techniques to evaluate the effects of FF and MS/DB lesions on alpha7 nicotinic receptors in stratum radiatum interneurons. Focal somatic application of ACh (1 mM) evoked methyllycaconitine (MLA)-sensitive currents that were markedly reduced following aspirative lesions of the FF. Reductions in current amplitudes were prevented or restored to levels not significantly different from controls following in vivo treatment with the alpha7-selective agonist GTS-21, and GTS-21 treatment did not change current amplitudes measured in tissue from unlesioned animals. MS/DB injections of the selective cholinergic neurotoxin 192 IgG-saporin did not affect alpha7 receptor currents, although MS/DB ChAT and hippocampal AChE immunolabeling were significantly reduced. In contrast, kainic acid lesions of the MS/DB, potentially more selective for GABAergic projection neurons, produced significant reductions in current amplitudes. These findings are the first to show functional changes in alpha7 receptors following hippocampal denervation and suggest that MS/DB hippocampal innervation regulates functional aspects of hippocampal alpha7 receptors. The results confirm hippocampal alpha7 nicotinic receptors as viable therapeutic targets in diseases that involve degradation of the septohippocampal pathway and may indicate that GABAergic MS/DB hippocampal input plays a more substantial role in the regulation of alpha7 nicotinic receptor function than MS/DB hippocampal cholinergic input.

Wire-Induced Myocardial Ischemia-A Novel Approach to Create Myocardial Ischemia in Rats-

BACKGROUND

Animal models are indispensable in order to investigate the mechanism of various diseases and to explore the counter measures for those disease states. Although there are several animal models of ischemic heart diseases, surgical interventions required to create myocardial ischemia sometimes give rise to a problem in the yield of model. This study describes a new technique for inducing myocardial ischemia in rats.

METHODS AND RESULTS

A 0.014-inch guidewire was introduced via the carotid artery and selectively advanced into the coronary arteries under fluoroscopy. Transmural myocardial ischemia was confirmed by ST-segment elevation and by the appearance of left ventricular wall motion abnormalities on the echocardiogram. Reversibility of the wire-induced myocardial ischemia was demonstrated by complete resolution of both ST-segment elevation and wall motion abnormalities after removing the wire.

CONCLUSION

Wire-induced myocardial ischemia was reproducible and is less invasive than conventional ischemic models in rats. This method is a powerful and useful tool for the investigation of ischemic heart disease in small animals.

Regulation of alveolar type II cell differentiation and proliferation in adult rat lung explants

Alveolar type II cells produce pulmonary surfactant and serve as the stem cell of the alveolar epithelium by proliferating and transforming into type I cells. The study of the differentiated function and proliferative capacity of type II cells in response to injury in vivo has been hindered by the complexity of the systemic response to injury. In vitro studies have in turn been limited by the impaired proliferative potential and loss of markers of differentiation in isolated type II cells maintained in culture. We describe an in vitro system in which type II cells proliferate spontaneously and simultaneously maintain differentiated characteristics. Other investigators have maintained slices of adult lung in culture after agarose infusion for up to 9 wk. To further develop this model for the study of epithelial cell differentiation and proliferation, we assessed epithelial differentiation, proliferative capacity, and regulation of cell-specific gene expression in slice explants of agarose-infused rat lungs. We prepared 1-mm-thick explants and maintained them in culture for up to 2 wk. Maintenance of differentiation was confirmed morphologically by light and electron microscopy, by the accumulation of epithelial cell-specific surfactant proteins, and by phospholipid analysis. Proliferative capacity was assessed by measuring [3H]thymidine incorporation in alveolar and small airway cells at baseline and in response to growth stimuli. Type II cell proliferation was inhibited in a dose-dependent manner by glucocorticoids. Glucocorticoids regulated RNA levels in explants in a manner similar to that seen in vivo and in fetal lung explants. The alveolar epithelium in adult lung slice explants maintains differentiated function and the ability to proliferate, thereby providing a useful system for the study of distal airway and alveolar cell homeostasis and response to injury.

Microencapsulation of isolated pituitary cells by polyacrylamide microlatex coagulation on agarose beads

Microlatex beads of homogenous size were made by polymerization of a mixture of acrylamide/bisacrylamide dispersed in a microemulsion. The microlatex was aggregated by dilution of the microemulsion in acrylamide solutions. The aggregates were then coagulated by polymerization at the interfaces of agarose beads circulating in a capillary tube containing paraffin oil. Biocompatibility was tested on isolated pituitary cells microencapsulated by this procedure.