Biochemical Effects of Exercise on a Fasciocutaneous Flap in a Rat Model.

IMPORTANCE: An overwhelming amount of data suggest that cardiovascular exercise has a positive effect on the mind and body, although the precise mechanism is not always clear. OBJECTIVE: To assess the clinical and biochemical effects of voluntary cardiovascular exercise on pedicled flaps in a rodent model. DESIGN, SETTING, AND PARTICIPANTS: Eighteen adult Sprague-Dawley male rats were randomized into a resting animal group (RAG) (n=9) and an exercise animal group (EAG) (n=9) for 14 days (July 23, 2013, through July 30, 2013). A pedicled transposition flap was performed on the ventral surface of the rat, and biopsy specimens were taken from the proximal, middle, and distal portions on postoperative days 0, 2, 5, and 9. Flap survival was analyzed planimetrically, and biopsy specimens were analyzed by hematoxylin-eosin-stained microscopy and immunoblotting. The housing, exercise, surgery, and analysis of the rats were conducted at a single basic science research laboratory at the tertiary care center campus of Thomas Jefferson University in Philadelphia, Pennsylvania. EXPOSURES: The rats were caged for 14 days or housed in a cage connected to an exercise wheel and pedometer. MAIN OUTCOMES AND MEASURES: Study measures were gross and micrographic necrosis and expression of proteins within cell survival and apoptosis pathways. RESULTS: A total of 18 rats were studied, 9 in the RAG and 9 in the EAG. the mean (SEM) amount of necrosis in flaps was 41.3% (3%) in the RAG rats and 10.5% (3.5%) in the EAG rats (P < .001). Immunoblotting revealed increased Caspase-9 activity resulting in poly-(adenosine diphosphate-ribose) polymerase 1 cleavage in the RAG vs the EAG, as well as lower phosphorylated protein kinase B (also known as Akt), signal transducer and activator of transcription 3, and total B-cell leukemia/lymphoma 2 protein levels. Throughout the postoperative period, the cumulative vascular endothelial growth factor A levels of the EAG flaps were significantly higher than those of the RAG flaps (2.30 vs 1.25 fold induction [FI], P = .002), with differences of 2.76 vs 1.54 FI in the proximal segment, 2.40 vs 1.20 FI in the middle segment, and 1.90 vs 0.79 FI in the distal segment. A similar response was noted when comparing phosphorylated Akt, with cumulative mean (SEM) p-Akt expression levels of 0.62 (0.04) for RAG and 1.98 (0.09) for EAG (P = .002 between the 2 groups). CONCLUSIONS AND RELEVANCE: Voluntary preoperative exercise improves survival in pedicled fasciocutaneous flaps; the EAG rats had less necrosis, decreased apoptotic markers, and increased amounts of vascular endothelial growth factor A and prosurvival proteins. These results have implications to increase flap survival in other mammal populations, such as humans. LEVEL OF EVIDENCE: 3.

Aging effects on pedicled fasciocutaneous flap survival in rats.

BACKGROUND: Poorer surgical outcomes in older patients undergoing locoregional head and neck reconstruction have raised questions about tolerance of aging tissue to iatrogenic ischemic insults. METHODS: We examined the effects of aging on viability of pedicled composite flaps in 2-month and 6-month old Sprague-Dawley male rats and correlated flap survival with vascular endogenous growth factor (VEGF) and VEGF receptor 2-mediated signaling events. Flap segments were assessed for gross/cellular necrosis by optical microscopy and for proangiogenic, apoptotic, and proliferative protein-marker content. RESULTS: Flap necrosis significantly increased with age (4.2% in young vs 49.17% in old), correlating with reduced expression of VEGF, inhibition of signal transducer and activator of transcription 3 (STAT3), and Akt activation, impaired Akt-dependent endothelial nitric oxide synthase (eNOS) phosphorylation, elevated Bax/Bcl-2 ratio, activation of Caspase-3, upregulated nuclear poly (ADP-ribose) polymerase-1 (PARP-1) cleavage and lower proliferating cell nuclear antigen (PCNA) levels. CONCLUSION: Pedicled flap survival is higher in younger rats in part because of unhindered expression of VEGF and enhanced activity of cell survival and promigratory signaling pathways. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1152-E1162, 2016.

Contrast-enhanced ultrasound-guided Sentinel lymph node biopsy of the ocular conjunctiva.

OBJECTIVES/HYPOTHESIS: Sentinel lymph node biopsy (SLNB) has been utilized for cutaneous melanoma and other malignancies arising from the eye and ocular adnexa. Currently, SLNB requires blue dyes and/or radiopharmaceuticals; both of which have significant shortcomings. This study sought to evaluate the feasibility of SLNB with the use of real-time, contrast-enhanced ultrasound (CEUS) as an alternative technique for tumors arising in the conjunctiva. STUDY DESIGN: Prospective feasibility study in a porcine model. METHODS: Twelve experiments were performed on six non-tumor-bearing Yorkshire swine. An ultrasound contrast agent, Sonazoid (GE Healthcare, Oslo, Norway), (99m) technetium ((99m) Tc), and methylene blue (MB) (Covidien, Mansfield, MA) were injected in the ocular conjunctiva. Sentinel lymph nodes (SLNs) were localized with CEUS and findings were compared to that of MB and (99m) Tc. Fisher exact test was used. RESULTS: Contrast-enhanced SLNs were identified within an average of 6.2 minutes from time of injection of Sonazoid. A total of 17 SLNs were identified by at least one of the three techniques. Correlation between Sonazoid and (99m) Tc was 94.1% (16/17 SLNs). Correlation between (99m) Tc and MB was 88.2% (15/17). One SLN that was positive for (99m) Tc but negative for Sonazoid and was considered to be a false positive (1/17); findings were similar for MB (1/17). Differences between the three techniques were not significant (P = .886). CONCLUSIONS: CEUS-guided injection of conjunctiva for SLNB is technically feasible and correlates well with standard detection techniques. This technique shows promise for rapid, real-time, intraoperative imaging for SLNB, using a widely available imaging modality and avoiding the need for radiopharmaceuticals. LEVEL OF EVIDENCE: NA

Sar1 assembly regulates membrane constriction and ER export.

The guanosine triphosphatase Sar1 controls the assembly and fission of COPII vesicles. Sar1 utilizes an amphipathic N-terminal helix as a wedge that inserts into outer membrane leaflets to induce vesicle neck constriction and control fission. We hypothesize that Sar1 organizes on membranes to control constriction as observed with fission proteins like dynamin. Sar1 activation led to membrane-dependent oligomerization that transformed giant unilamellar vesicles into small vesicles connected through highly constricted necks. In contrast, membrane tension provided through membrane attachment led to organization of Sar1 in ordered scaffolds that formed rigid, uniformly nonconstricted lipid tubules to suggest that Sar1 organization regulates membrane constriction. Sar1 organization required conserved residues located on a unique C-terminal loop. Mutations in this loop did not affect Sar1 activation or COPII recruitment and enhanced membrane constriction, yet inhibited Sar1 organization and procollagen transport from the endoplasmic reticulum (ER). Sar1 activity was directed to liquid-disordered lipid phases. Thus, lipid-directed and tether-assisted Sar1 organization controls membrane constriction to regulate ER export.