Clinical Research Abstracts of the British Equine Veterinary Association Congress 2015.

REASONS FOR PERFORMING STUDY: Blackthorn (Prunus spinosus) is recognised as causing infections and tissue reactions. OBJECTIVES: To describe the presentation, diagnosis, treatment and outcome of blackthorn plant thorn synovitis in the horse. STUDY DESIGN: Case series. METHODS: All cases in this prospective study presented with acute onset synovitis within 24 h of thorn penetration, had a standardised clinical assessment, surgical treatment and aftercare. Surgical treatment was performed within 24 h of presentation under general anaesthesia, using a 2-stage procedure: Stage 1: perisynovial technique. Ultrasound guided placement of a 20 gauge 35 mm needle marker that is used as a guide for electrosurgical dissection onto perisynovial thorn fragments. Stage 2: endoscopic technique. Using standard and novel portals to locate and remove thorn fragments and debris from synovial structures. RESULTS: Thirty-five cases met the study inclusion criteria over a 24 month period. Mean lameness score on presentation was 4/5 (range 1-5). The most commonly affected structures were fetlock joints (11/35) and tendon sheaths (10/35). Mean synovial fluid total protein was 50.5 g/l (range 18-116), and TNCC was 158 x 10(9) (range 21-412) on presentation and 12 x 10(9) (range 1-46) at 48 h post operatively. All synovial fluid cultures were negative. All horses were sound (grade 0) at 5 days post operatively and all returned to full work. CONCLUSIONS: There are a limited number of case series of blackthorn injury in humans; however, the consensus is that surgical treatment is required for a successful outcome. The 2-stage surgical procedure described, achieved accurate identification and removal of thorn material in all cases. In contrast to previous studies on synovial sepsis, these cases had a positive outcome despite high pre- and post operative synovial fluid total protein and TNCC. These findings suggest that thorn synovitis cases have a different aetiology from synovitis originating from sepsis or contamination. Ethical animal research: The study was reviewed and approved by the Ethics Committee, School of Veterinary Medicine and Science, University of Nottingham. Owners gave informed consent for their horses' inclusion in the study. SOURCE OF FUNDING: None. Competing interests: None declared.

Adenosine and adenine nucleotides inhibit the autonomous and epidermal growth factor-mediated proliferation of cultured human keratinocytes.

Previous investigations have shown disparate effects of adenine nucleotides on epidermal cell proliferation. Our present study demonstrates that adenosine and its related nucleotides (ATP, ADP, AMP) are antiproliferative for normal human epidermal keratinocytes cultured in the absence or presence of exogenous epidermal growth factor. Furthermore, the inhibitory effects of these compounds occur at concentrations less than 100 microM, are reversible, and do not affect the viability of the keratinocyte cultures. Our current investigation also demonstrates that both selective and nonselective adenosine receptor agonists are themselves approximately as potent as keratinocyte proliferation inhibitors, but are all less potent inhibitors than adenosine. These observations are consistent with the theory that adenosine mediates its antiproliferative response via a novel or more poorly characterized adenosine purinoreceptor subclass. Moreover, our present study demonstrates that ATP and ATP-gamma-S are significantly more potent antiproliferative agents than either alpha,beta-methylene ATP or beta,gamma-methylene ATP. Based on previous studies that have demonstrated that P2y purinoreceptors possess this type of ligand specificity and that the P2y purinoreceptor may be expressed by keratinocyte cultures, we propose that ATP may mediate its antiproliferative effects via this purinoreceptor. Collectively, our results indicate that adenosine and adenine nucleotides abrogate exogenous epidermal growth factor-dependent and -independent keratinocyte proliferation at submillimolar concentrations and may be important physiologic regulators of keratinocyte growth in vivo. Further, these results suggest that these or related compounds may have application as treatments for epidermal growth factor receptor-signaling pathway has been activated.

Differential effects of a heparin antagonist (hexadimethrine) or chlorate on amphiregulin, basic fibroblast growth factor, and heparin-binding EGF-like growth factor activity.

Amphiregulin (AR) and heparin-binding EGF-like growth factor (HB-EGF) are two recently identified members of the EGF family. Both AR and HB-EGF share with EGF the ability to interact with the type-1 EGF receptor; however, AR and HB-EGF differ from EGF in that both of these mitogens bind to heparin while EGF does not. To determine whether interactions with heparin-like molecules on the cell surface influence binding of AR and HB-EGF with EGF receptors and the subsequent mitogenic activity exerted by these growth factors, murine AKR-2B and Balb/MK-2 cells were treated with either an inhibitor of proteoglycan sulfation (chlorate) or a heparin antagonist (hexadimethrine). As expected, neither treatment significantly altered the specific binding of 125I-EGF on AKR-2B cells. Interestingly, treatment with either chlorate or hexadimethrine inhibited the ability of AR to compete with 125I-EGF for cell surface binding and also attenuated AR-mediated DNA synthesis. Thus, as has been suggested for other heparin-binding growth factors such as basic fibroblast growth factor (bFGF), the interaction of AR with an EGF-binding receptor appears to be facilitated by interaction with cell-associated sulfated glycosaminoglycans or proteoglycans. Unexpectedly, however, neither chlorate nor hexadimethrine treatment caused an inhibition of HB-EGF-induced mitogenic activity. Chlorate treatment did not significantly alter the ability of HB-EGF to compete with 125I-EGF for cell surface binding sites, however, heparin and hexadimethrine reduced the ability of HB-EGF to compete for 125I-EGF binding. These results suggest that, in AKR-2B cells, HB-EGF may mediate its mitogenic response at least in part through a receptor which appears to be selective for HB-EGF and permits HB-EGF-mediated mitogenic responses in the presence of hexadimethrine or heparin. Finally, hexadimethrine inhibited the specific binding and mitogenic activity of bFGF, suggesting that this cationic polymer can function as an antagonist of heparin-binding mitogens other than AR.