Mussel-inspired antimicrobial gelatin/chitosan tissue adhesive rapidly activated in situ by H2O2/ascorbic acid for infected wound closure.

The development of minimally invasive surgery has created a demand for ideal medical adhesives exhibiting biocompatibility, biodegradability, antimicrobial activity, and strong adhesion to tissues in wet environments. However, as clinically approved surgical tissue glues suffer from poor adhesion activation, limited adhesion strength, and toxicity, novel tissue glues are highly sought after. Herein, a mussel-inspired injectable hydrogel was prepared from catechol- and methacrylate-modified chitosan/gelatin and shown to exhibit biocompatibility, inherent antimicrobial activity, and good adhesion to wet tissues. Moreover, as this gel could be applied onto tissue surfaces and cured in situ within seconds of body contact by a biocompatible and multifunctional redox initiator (H2O2-ascorbic acid), it was concluded to be a promising surgical sealant and wound dressing (even for infected wounds) accelerating wound healing.

Signaling Mechanism of Cannabinoid Receptor-2 Activation-Induced ß-Endorphin Release.

Activation of cannabinoid receptor-2 (CB2) results in ß-endorphin release from keratinocytes, which then acts on primary afferent neurons to inhibit nociception. However, the underlying mechanism is still unknown. The CB2 receptor is generally thought to couple to Gi/o to inhibit cAMP production, which cannot explain the peripheral stimulatory effects of CB2 receptor activation. In this study, we found that in a keratinocyte cell line, the Gßγ subunits from Gi/o, but not Gαs, were involved in CB2 receptor activation-induced ß-endorphin release. Inhibition of MAPK kinase, but not PLC, abolished CB2 receptor activation-induced ß-endorphin release. Also, CB2 receptor activation significantly increased intracellular Ca(2+). Treatment with BAPTA-AM or thapsigargin blocked CB2 receptor activation-induced ß-endorphin release. Using a rat model of inflammatory pain, we showed that the MAPK kinase inhibitor PD98059 abolished the peripheral effect of the CB2 receptor agonist on nociception. We thus present a novel mechanism of CB2 receptor activation-induced ß-endorphin release through Gi/o-Gßγ-MAPK-Ca(2+) signaling pathway. Our data also suggest that stimulation of MAPK contributes to the peripheral analgesic effect of CB2 receptor agonists.

Design, synthesis and biological activity of flavonoid derivatives as selective agonists for neuromedin U 2 receptor.

Central neuromedin U 2 receptor (NMU2R) plays important roles in the regulation of food intake and body weight. Identification of NMU2R agonists may lead to the development of pharmaceutical agents to treat obesity. Based on the structure of rutin, a typical flavonoid and one of the NMU2R agonists we previously identified from an in-house made natural product library, 30 flavonoid derivatives have been synthesized and screened on a cell-based reporter gene assay. A number of compounds were found to be selective and highly potent to NMU2R. For example, the EC50 value of compound NRA 4 is very close to that of NMU, the endogenous peptide ligand of NMU2R. Structure-activity relationship analysis revealed that a 3-hydroxyl group in ring C and a 2'-fluoride group in ring B were essential for this class of compounds to be active against NMU2R.

[MSCT diagnosis of foot and ankle tendon injury].

OBJECTIVE: To study the MSCT features and diagnosis of foot and ankle tendon injury and improve the recognition to avoid the missed. METHODS: From January 2009 to December 2010, 32 patients suspected of foot and ankle tendon injury were enrolled and included 24 males and 8 females with an average age of 43 years ranging from 23 to 68 years. All patients had pain, tenderness, swelling or disfunction in the diseased foot and were finally confirmed with surgery, MRI, contralateral contrast and followed-up. The MSCT was performed with a multi-detector CT scanner (Emotion 6; Siemens) within 7 days after injury. Two experienced radiologists evaluated the tendon abnormalities before told the outcome. RESULTS: With 5 patients lost, the final study included 27 patients. Thirty-one tendon injuries were finally confirmed in 23 cases. Thirty-five tendon abnormalities were diagnosed on CT images among all 243 tendons but 4 of them were misdiagnoses. The CT overall diagnostic sensitivity, specificity, and accuracy was 88.8% (31/35), 98.1% (208/212), and 98.4% (239/243). Eleven tendon dislocations showed as the tendon partially or completely off the tendon groove. Thirteen tendon entrapment showed no less than half section of the tendon embedded the fracture in the axial images, and 7 tendons located in the fracture gap or 6 tendons closely related with widened fracture in VR images (2 misdiagnosis). Four bone chip insertion showed the chip inserted in the tendons both in the axial images and VR images (1 misdiagnosis). Four tendon ruptures showed discontinuity and shortening of the tendon (1 misdiagnosis). Three tendon injuries showed thickening, density reduction and blurring of tendons, and misty surrounding fat space. CONCLUSION: With comprehensive MSCT examination (thin-slice scanning and volume rendering) of foot and ankle, the tendon dislocation, tendon entrapment, bone chip intercalation, and tendon rupture/injury could be confidently diagnose.

Cannabinoid CB2 receptors contribute to upregulation of ß-endorphin in inflamed skin tissues by electroacupuncture.

BACKGROUND: Electroacupuncture (EA) can produce analgesia by increasing the ß-endorphin level and activation of peripheral µ-opioid receptors in inflamed tissues. Endogenous cannabinoids and peripheral cannabinoid CB2 receptors (CB2Rs) are also involved in the antinociceptive effect of EA on inflammatory pain. However, little is known about how peripheral CB2Rs interact with the endogenous opioid system at the inflammatory site and how this interaction contributes to the antinociceptive effect of EA on inflammatory pain. In this study, we determined the role of peripheral CB2Rs in the effects of EA on the expression of ß-endorphin in inflamed skin tissues and inflammatory pain. RESULTS: Inflammatory pain was induced by injection of complete Freund's adjuvant into the left hindpaw of rats. Thermal hyperalgesia was tested with a radiant heat stimulus, and mechanical allodynia was quantified using von Frey filaments. The mRNA level of POMC and protein level of ß-endorphin were quantified by real-time PCR and Western blotting, respectively. The ß-endorphin-containing keratinocytes and immune cells in the inflamed skin tissues were detected by double-immunofluorescence labeling. The CB2R agonist AM1241 or EA significantly reduced thermal hyperalgesia and mechanical allodynia, whereas the selective µ-opioid receptor antagonist ß-funaltrexamine significantly attenuated the antinociceptive effect produced by them. AM1241 or EA significantly increased the mRNA level of POMC and the protein level of ß-endorphin in inflamed skin tissues, and these effects were significantly attenuated by pretreatment with the CB2R antagonist AM630. AM1241 or EA also significantly increased the percentage of ß-endorphin-immunoreactive keratinocytes, macrophages, and T-lymphocytes in inflamed skin tissues, and these effects were blocked by AM630. CONCLUSIONS: EA and CB2R stimulation reduce inflammatory pain through activation of µ-opioid receptors. EA increases endogenous opioid expression in keratinocytes and infiltrating immune cells at the inflammatory site through CB2R activation.