Antimicrobial assessment of a chitosan microfibre dressing: a natural antimicrobial.

OBJECTIVE: Chitosan is a natural biopolymer and is the main structural component of the cuticles of crustaceans, insects and molluscs and the cell walls of certain fungi. It is abundant in nature and is naturally antimicrobial. A natural fibre has been created with chitosan and is being used as a wound dressing, namely Kytocel. It is an absorbent fibre dressing that is claimed to be biodegradable and biocompatible. This study was undertaken to assess the antimicrobial properties of the microfibre wound dressing using a variety of methods commonly used to assess other antimicrobial dressings. METHOD: The zone of inhibition (ZOI) assay, challenge test (log reduction), time-to-kill and an in vitro wound model were all used in this report. Representative Gram-positive and Gram-negative bacteria were used and one yeast, Candida albicans. RESULTS: The ZoI test showed no observable zones around the dressing but killed the organisms underneath the dressing. There was a >3 log reduction of Staphylococcus aureus and Escherichia coli within two hours and >3 log reduction against Pseudomonas aeruginosa and Candida albicans between four and 24 hours in the challenge test. In the wound model, there was a 2 log reduction of Escherichia coli within the wound model and in the sponge and culture medium below the dressing. CONCLUSION: The chitosan microfibre wound dressing gives wound care an additional dressing to use to help prevent and manage bioburden and wound infection.

In vitro and in vivo assessment of lactic acid-modified chitosan scaffolds for potential treatment of full-thickness burns.

Autologous skin transplantation is today's "gold standard" treatment for full-thickness burns. However, when > 30% of total body surface area is damaged, there is an important shortage of autologous donor sites for skin grafting; then, treatment alternatives become crucial. Such alternatives can be based on polymeric scaffolds capable of functioning as protective covers and cells/factors carriers. Chitosan (CTS) is a natural-derived polymer with relevant biological-related properties but poor mechanical performance. Improved mechanical properties can be achieved through lactic acid grafting (LA-g); nevertheless, LA-g affects the biological response towards the CTS-based materials. In this work, CTS-LA scaffolds with different LA-g percentages were synthesized and evaluated to determine appropriate LA-g degrees for full-thickness burns treatment. In vitro results indicated that the higher the LA-g percentage, the lower the capability of the scaffolds to sustain fibroblasts culture. Scaffolds with LA-g around 28% (CTS-LA28) sustained cell culture and allowed normal cell functionality. Further evaluation of CTS-LA28 as acellular and cellular grafts in a full-thickness burn mouse model showed that at 28 days post-burn, macroscopic characteristic of the reparation tissue were closer to healthy skin when cellular grafts were used for treatment; histological evaluation also showed that dermis cellularity and collagenous fibers structure were similar to those in healthy skin when cellular grafts were used for burns treatment. © 2017 Wiley Periodicals Inc. J Biomed Mater Res Part A: 105A: 2875-2891, 2017.

Norfloxacin-loaded collagen/chitosan scaffolds for skin reconstruction: Preparation, evaluation and in-vivo wound healing assessment.

Biomaterial scaffolds are versatile tools as drug carrier for treatment of wounds. A series of norfloxacin-loaded scaffolds were synthesized for treatment of wounds by combining collagen with two different types of chitosan using freeze-drying technique. Subsequently, scaffolds were screened in terms of morphology, water absorption and retention capacity, biodegradation, ex-vivo bioadhesive strength, in-vitro drug release biological compatibility, X-ray diffractometry, differential scanning calorimetry as well as in-vivo evaluation. The results indicate that the scaffold mechanical strength is dependent on the type of used chitosan. The prepared scaffolds contained interconnected porous architecture. The scaffolds had high water uptake and retention capacity with extended biodegradation rate. Scaffolds prepared with chitosan HCl showed superior bioadhesive strength compared to those prepared with low molecular weight chitosan. All scaffolds showed almost 100% drug release within 24h. As identified by the terahertz pulsed imaging measurements, there is single scaffold area with the same concentration. After 28 days of wound dressing with selected norfoloxacin-loaded or unloaded collagen/chitosan scaffolds in Albino rats, it was found that the tissue regeneration time was fast compared to non-treated wounds. Furthermore, the drug-loaded scaffolds showed normal structure of an intact epidermal layer as well as the underlying dermis as revealed by histopathological studies. The obtained results suggest that the investigated norfloxacin-loaded collagen/chitosan scaffold is a potential candidate for skin regeneration application.

Usefulness of real-time elastography strain ratio in the assessment of bile duct ligation-induced liver injury and the hepatoprotective effect of chitosan: an experimental animal study.

The purpose of the study described here was to evaluate the usefulness of the elastographic strain ratio in the assessment of liver changes in an experimental animal setting and the hepatoprotective effects of chitosan. Ultrasonography and Strain Ratio calculation were performed before and after bile duct ligation (BDL) in three groups of Wistar albino rats (n = 10 animals per group): (i) rats subjected to bile duct ligation only; (ii) rats subjected to bile duct ligation and administered chitosan for 14 d; (iii) rats subjected to bile duct ligation and administered chitosan for 7 d. The results were compared with the laboratory data and pathologic findings. Strain ratios revealed an increase in liver stiffness after bile duct ligation (p < 0.05), except in the group with chitosan administered for 7 d, and agreed with laboratory and pathology data. In conclusion, strain ratio can be used as an experimental research instrument in the assessment of liver response to injury. To the best of our knowledge, this is the first study reporting on the usefulness of the sonoelastographic liver-to-kidney strain ratio in assessing the effects of experimentally induced liver lesions.

Clinical and instrumental assessment of the effects of a new product based on hydroxypropyl chitosan and potassium azeloyl diglycinate in the management of rosacea.

BACKGROUND: Rosacea is a chronic inflammatory skin disease affecting mostly facial skin. Its origin is multifactorial. Important steps in its treatment are avoidance of any triggering factor and control of skin inflammation. AIM: To assess the benefit of topical applications of a new product (P-3075). PATIENTS/METHODS: A randomized, multicenter, double-blind, placebo-controlled, parallel-group, pilot study was carried out to evaluate the efficacy and tolerability of a cream (P-3075) based on 5% potassium azeloyl diglycinate (PAD, Azeloglicina(®)) and 1% hydroxypropyl chitosan (HPCH). Forty-two patients (rosacea stages I and II) were enrolled and randomized, 28 in the P-3075 group and 14 in the placebo group. They were asked to apply the cream twice daily for 4 weeks. The main assessments were the objective quantification of erythema and skin hydration using the Mexameter(®) and Corneometer(®) devices, respectively. Clinical signs and symptoms were evaluated on a four-point scale. RESULTS: The P-3075 cream applied for 28 days was effective in skin protection by reducing erythema, evaluated both instrumentally and clinically. In addition, the clinical assessments of other symptoms such as flushing, stinging, and burning supported the beneficial effect of the P-3075 cream. CONCLUSIONS: The anti-inflammatory and moisturizing effects of potassium azeloyl diglycinate combined with the protective properties of HPCH allow the new product to be a good candidate for controlling signs and symptoms of rosacea.

Assessment of hemostatic efficacy and osseous wound healing using HemCon dental dressing.

INTRODUCTION: Obtaining hemostasis in the surgical crypt during periradicular surgery is essential. It allows for improved visibility and contributes to a dry environment suitable for the placement of moisture-sensitive root-end filling material. Although current materials may not be moisture sensitive during setting, hemostasis is important for proper placement of root-end filling materials during apical surgery. A new hemostatic agent, HemCon dental dressing (Patterson Dental, St Paul, MN), may improve upon the efficacy of wound healing and hemostasis both in extent and time. The aim of this study was to evaluate the hemostatic effect of HemCon in osseous wound sites and evaluate the wound healing potential and percentage of new bone formation in osseous crypts treated with HemCon. METHODS: A split-mouth design was used with random allocation of sham and experimental sites in 12 rabbits. In experimental sites, either HemCon or 15.5% ferric sulfate was applied to osseous crypts created with a round bur. Hemostatic efficacy was evaluated using predetermined scores. Rabbits were sacrificed at 21 days, and tissues were harvested and prepared for histologic evaluation. A blinded pathologist scored samples relative to inflammation. The percentage of new bone deposition was calculated using NIS Elements software (Nikon Instruments Inc, Melville, NY). RESULTS: There was no statistical significant difference in hemostatic efficacy or wound healing between HemCon and ferric sulfate (P > .05). The HemCon group showed a significantly higher percentage of new bone deposition compared with the controls (P < .01). CONCLUSIONS: HemCon shows promise as an adjunct to the endodontic surgical armamentarium.

A randomised controlled trial on the effectiveness of an advanced wound dressing used in Iran.

OBJECTIVE: To compare the wound healing rate and incidence of infection in wounds treated with either a bioactive dressing (containing hydrophilic mucopolysaccharide, chitosan) or conservative treatment (gauze). METHOD: Eighty-five patients with diabetic foot ulcers, pressure ulcers or leg ulcers were randomised to receive either the bioactive study dressing (n=33 patients, 45 wounds) or the control dressing (n=52 patients, 53 wounds) for 21 days. Wound size, stage where appropriate and the presence of infection were recorded at each dressing change. Thirty-one of these 85 patients dropped out of the study during the three-month post-treatment follow-up, when wound size and grade were assessed on a monthly basis. Data were therefore analysed on 54 patients, of whom 32 (34 wounds) were in the treatment group and 22 (26 wounds) in the control group. RESULTS: In the control group, four pressure ulcers healed, but the remaining wounds all deteriorated and became infected, requiring antibiotics. In contrast, in the treatment group 29/34 wounds healed completely, and none became infected; the remaining five wounds healed during the follow-up period. The difference between the two groups in the number of wounds that healed was statistically significant (p<0.001), as was that for the number of healed pressure ulcers p<0.05. CONCLUSION: Use of a moist bioactive wound dressing significantly increased the healing rate when compared with the traditional dressings used in the participating hospitals. This will in turn bring significant cost savings.