The effects of topical mafenide acetate application on skin graft survival in bacterial contaminated wounds.

BACKGROUND: Infection related skin graft loss still remains as a common problem even with the use of systemic antibiotics. Mafenide acetate (Sulfamylon) is a topical antimicrobial agent with a wide spectrum of antimicrobial activity. Since mafenide acetate has the ability to penetrate the burn eschar, it was preferred in the treatment of infected full-thickness skin grafts. We investigated the effects of topical Mafenide acetate application on graft survival in an experimental model of contaminated wound beds in rats. MATERIALS AND METHODS: Twenty-eight male Wistar albino rats were included in the study. A full-thickness skin graft (FTSG) was harvested from the back region and the wound bed was inoculated with Pseudomonas aeruginosa. The same FTSG was sutured in place. Rats were divided into 4 groups. In groups 1 and 2, wound care was performed with gauze and hydrofiber dressings respectively. In groups 3 and 4, Mafenide acetate soaked hydrofiber and Mafenide acetate soaked gauze dressings were used respectively. The dressings were closed for 4 days in all groups. The rats in groups 1 and 2 received dressing changes every day. The dressing of the rats in group 3 was changed once every two days. The dressing of the rats in group 4 was changed twice a day. RESULTS: In groups 3 and 4, the graft survival rates decreased significantly from day 7 to day 14 in all groups. Histologically, detachment at the dermoepidermal junction, disorganization of collagen along with increased numbers of fibroblasts and a decrease in graft adhesion to the wound bed were determined in Mafenide acetate-treated groups. CONCLUSION: In rats treated with Mafenide acetate, graft survival was higher on day 7 and gradually decreased towards day 14. Application of a 2.5% solution of Mafenide acetate longer than 7 days on inoculated skin grafts in a rat model causes significant cytotoxicity and graft loss.

Hyaluronic Acid Dermal Filler Promotes Cartilage Reshaping in Rabbit Ears.

BACKGROUND: Neonatal ear is more malleable and soft, allowing the correction of deformities by using external molding. This is mainly attributed to high concentration of the proteoglycan aggregate and hyaluronic acid. In this study, HA dermal filler was injected in rabbit ear as a long acting HA source to investigate the biological impact of HA in reshaping the ear cartilage. MATERIALS AND METHODS: Ears of twelve rabbits were divided into 4 groups. Control group was the left ears of 6 animals which were left intact. Group 2 was the right ears of the same animals, which received saline solution injection. Group 3 was the left ears of the other 6 animals, which were given 1 mL of HA. Group 4 was the right ears of them, which were given 2 mL of HA in both sites of the ear. All ears were folded and splinted for 4 weeks. Then, the angle of each ear was calculated. Following an additional 4 weeks, a cartilage biopsy was taken for histological examination. RESULTS: The ear angles did not show any statistical difference at week 4. There was a significant difference among the groups at the 8th week. In the 3rd and 4th groups, mean angles were higher than the group 1 and group 2. Thickening in the cartilage and ectopic cartilage formation was observed in the contact areas to hyaluronic acid. Significant difference was also found between the peak and mean cartilage thicknesses. CONCLUSION: HA dermal filler can stimulate cartilage regeneration by increasing the synthesis of extracellular matrix and chondrogenesis especially where it is in direct contact with the ear cartilage. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The interaction of l-cysteine/H2S pathway and muscarinic acetylcholine receptors (mAChRs) in mouse corpus cavernosum.

The aim of this study was to investigate the possible interaction of l-cysteine/H2S pathway and muscarinic acetylcholine receptors (mAChRs) in the mouse corpus cavernosum (CC). l-cysteine (endogenous H2S substrate; 10-6-10-3 M), sodium hydrogen sulfide (NaHS; exogenous H2S; 10-6-10-3 M) and acetylcholine (10-9-10-4 M) produced concentration-dependent relaxation in isolated mouse CC tissues. Relaxations to endogenous and exogenous H2S were reduced by non-selective mAChR antagonist atropine (5 × 10-5 M), selective M1 mAChR antagonist pirenzepine (5 × 10-5 M) and selective M3 mAChR antagonist 4-DAMP (10-7 M) but not by selective M2 mAChR antagonist AF-DX 116 (10-6 M). Also, acetylcholine-induced relaxations were reduced by atropine, pirenzepine, 4-DAMP and AF-DX 116, confirming the selective effects of mAChR antagonists. Furthermore, acetylcholine-induced relaxations were attenuated by cystathionine-gamma-lyase (CSE) inhibitor d,l-propargylglycine (PAG, 10-2 M) and cystathionine-ß-synthase inhibitor (CBS) aminooxyacetic acid (AOAA, 10-3 M). l-nitroarginine, nitric oxide synthase inhibitor, augmented the inhibitory effects of mAChR antagonists and H2S enzyme inhibitors on acetylcholine-induced relaxations. In addition, the existence and localization of CSE, CBS and 3-MST were demonstrated in mouse CC. Furthermore, tissue acetylcholine release was significantly increased by l-cysteine but not by exogenous H2S. The increase in acetylcholine level was completely inhibited by AOAA and PAG. These results suggest that M1 and M3 mAChRs contributes to relaxant effect mediated by endogenous H2S but at same time l-cysteine triggers acetylcholine release from cavernosal tissue. Also, the role of NO in the interaction of l-cysteine/H2S pathway and muscarinic acetylcholine receptors (mAChRs) could not be excluded.