Long-term outcome of autologous fascia lata grafting with conjunctival flap overlay in horses with ulcerative keratitis and keratomalacia.

OBJECTIVES: To describe the technique, postoperative complications, and outcome after autologous fascia lata grafting with conjunctival flap overlay in horses with ulcerative keratitis and keratomalacia. STUDY DESIGN: Retrospective case series. ANIMALS: Eleven horses with ulcerative keratitis and keratomalacia. METHODS: Horses included had undergone fascia lata grafting with conjunctival flap overlay due to impending or recent corneal perforation. Preceding therapy, lesion characteristics, postoperative complications, and short- and long-term outcomes were recorded. RESULTS: Postoperative complications included complete (1/11) or partial (2/11) dehiscence of the conjunctival flap and fascia lata graft, postoperative pneumonia (1/11), intermittent hypercreatinemia (2/11) and mild uveitis after trimming of the conjunctival flap (9/10). The donor sites healed without complications (11/11). A satisfactory short-term outcome (at cessation of medical therapy) was achieved in all horses (11/11). Long-term follow-up (median 29 months, range 7-127 months) was available for 10/11 horses. A comfortable eye with functional vision was achieved in 9/10 horses with long-term follow-up, including 3/4 horses with prior corneal perforation and 1/11 horses in which the fascia lata graft completely dehisced 15 days after surgery. Enucleation was required in a single horse (1/10) after phthisis bulbi developed 7 months postoperatively. CONCLUSION: Fascia lata grafting with conjunctival flap overlay appears to be a viable solution for globe preservation in horses with ulcerative keratitis and keratomalacia. Long-term ocular comfort with functional visual outcomes can be achieved in most cases with limited concerns for donor site morbidity while bypassing acquisition, storage or lesion-size limitations related to other biomaterials.

Insights into the Genetic Variations of Human Cytochrome P450 2C9: Structural Analysis, Characterization and Comparison.

Cytochromes P450 (CYP) are one of the major xenobiotic metabolizing enzymes with increasing importance in pharmacogenetics. The CYP2C9 enzyme is responsible for the metabolism of a wide range of clinical drugs. More than sixty genetic variations have been identified in CYP2C9 with many demonstrating reduced activity compared to the wild-type (WT) enzyme. The CYP2C9*8 allele is predominantly found in persons of African ancestry and results in altered clearance of several drug substrates of CYP2C9. The X-ray crystal structure of CYP2C9*8, which represents an amino acid variation from arginine to histidine at position 150 (R150H), was solved in complex with losartan. The overall conformation of the CYP2C9*8-losartan complex was similar to the previously solved complex with wild type (WT) protein, but it differs in the occupancy of losartan. One molecule of losartan was bound in the active site and another on the surface in an identical orientation to that observed in the WT complex. However, unlike the WT structure, the losartan in the access channel was not observed in the *8 complex. Furthermore, isothermal titration calorimetry studies illustrated weaker binding of losartan to *8 compared to WT. Interestingly, the CYP2C9*8 interaction with losartan was not as weak as the CYP2C9*3 variant, which showed up to three-fold weaker average dissociation constant compared to the WT. Taken together, the structural and solution characterization yields insights into the similarities and differences of losartan binding to CYP2C9 variants and provides a useful framework for probing the role of amino acid substitution and substrate dependent activity.

Use of autologous fascia lata graft to repair a complex corneal ulcer in a mare.

BACKGROUND: Application of an autogenous fascia lata graft in the treatment of keratomalacia in the horse has not been reported. The present case describes the use of an autologous fascia lata graft to surgically treat a complicated corneal ulcer in a horse. CASE PRESENTATION: A 12-year-old Arabian mare was admitted to Sharjah Equine Hospital with a history of right eye ulcerative keratitis of unknown duration. Following a week of aggressive medical treatment, the condition deteriorated and a keratectomy and pedicle conjunctival graft were performed. A week later, the conjunctival graft partially dehisced and the ulcer continued to degrade.In attempting to preserve the integrity of the globe a second grafting procedure was performed when a segment of fascia lata harvested from the ipsilateral hind leg was grafted onto the corneal lesion.Response to surgery was positive and the mare was discharged from the hospital on Day 31 post diagnosis (17 days after the second surgery) with a comfortable eye.Follow-up12 months later revealed a comfortable but only partially visual eye due to corneal scarring. CONCLUSION: Although the graft actually failed from the point of view of tissue integration, fascia lata appears to be a readily available, effective and affordable autografting material and we believe this technique has potential for short term physical and structural support of severe malacic or other complex corneal ulcers.

Extracellular vesicles: another compartment for the second messenger, cyclic adenosine monophosphate.

The second messenger, cAMP, is highly compartmentalized to facilitate signaling specificity. Extracellular vesicles (EVs) are submicron, intact vesicles released from many cell types that can act as biomarkers or be involved in cell-to-cell communication. Although it is well recognized that EVs encapsulate functional proteins and RNAs/miRNAs, currently it is unclear whether cyclic nucleotides are encapsulated within EVs to provide an additional second messenger compartment. Using ultracentrifugation, EVs were isolated from the culture medium of unstimulated systemic and pulmonary endothelial cells. EVs were also isolated from pulmonary microvascular endothelial cells (PMVECs) following stimulation of transmembrane adenylyl cyclase (AC) in the presence or absence of the phosphodiesterase 4 inhibitor rolipram over time. Whereas cAMP was detected in EVs isolated from endothelial cells derived from different vascular beds, it was highest in EVs isolated from PMVECs. Treatment of PMVECs with agents that increase near-membrane cAMP led to an increase in cAMP within corresponding EVs, yet there was no increase in EV number. Elevated cell cAMP, measured by whole cell measurements, peaked 15 min after treatment, yet in EVs the peak increase in cAMP was delayed until 60 min after cell stimulation. Cyclic AMP was also increased in EVs collected from the perfusate of isolated rat lungs stimulated with isoproterenol and rolipram, thus corroborating cell culture findings. When added to unperturbed confluent PMVECs, EVs containing elevated cAMP were not barrier disruptive like cytosolic cAMP but maintained monolayer resistance. In conclusion, PMVECs release EVs containing cAMP, providing an additional compartment to cAMP signaling.

Repair of an oronasal fistula with a two-layer closure method involving an autogenous fascia lata graft and oral mucosal flap in a pony.

CASE DESCRIPTION: A 9-year-old pony gelding was evaluated because it was suspected that a persistent oronasal fistula had developed after a fractured right maxillary second premolar tooth had been extracted via repulsion 6 months earlier. CLINICAL FINDINGS: Unilateral mucopurulent nasal discharge and malodorous breath were noted on clinical examination. Examination of the oral cavity revealed a 1 × 0.5-cm defect at the oral aspect of the right maxillary second premolar alveolus, from which feed material was extracted. Endoscopic examination revealed feed material in the rostral aspect of the right nasal cavity, confirming the diagnosis of oronasal fistula. TREATMENT AND OUTCOME: The pony initially underwent a reconstructive surgical procedure that combined an alveolar bone flap with a sliding mucoperiosteal hard palate flap to repair the oronasal fistula. The fistula reoccurred 5 months later and was ultimately repaired by means of a novel 2-layer flap closure method involving an autogenous fascia lata graft and oral mucosa flap. CLINICAL RELEVANCE: Fascia lata was effective as a scaffolding graft for repair of the oronasal fistula in this pony and may be useful for repair of oronasal fistulas in other equids as well.