Acute abdominal dehiscence following laparotomy: A multicentre, international retrospective study.

BACKGROUND: Incisional complications are a common cause of morbidity following laparotomy. Although uncommon, acute abdominal dehiscence (AAD) is a potentially fatal post-operative complication. However, few AAD cases are described in the literature. OBJECTIVES: To describe common features of cases of AAD following ventral midline laparotomy, management and outcomes. STUDY DESIGN: Retrospective case series. METHODS: Hospital records of horses that underwent a ventral midline laparotomy at nine hospitals in the UK, Ireland and USA over a 10-year period (2009-2019) were reviewed. Data were collected for pre-, intra- and post-operative factors that were considered relevant. Descriptive statistical analysis was performed. RESULTS: A total of 63 cases of AAD were identified. AAD occurred due to tearing of sutures through the linea alba or rupture of the body wall adjacent to the suture line in 46 horses (73%). AAD occurred at a median of 5 days (0.5-70 days) post-operatively and broodmares accounted for 25% of the cases (n = 16). Surgical site infection developed prior to AAD in 28 horses (44%); leakage of peritoneal fluid occurred in 5% of horses prior to AAD being identified. Surgical repair was performed in 27 horses (43%), 10 (16%) were treated conservatively and 26 (41%) were euthanised immediately. Repair was most frequently performed using suture (n = 14), wire (n = 5) or a combination (n = 5). Overall survival to hospital discharge was 39% (24/63). Where surgical repair was performed, 15 horses (56%) survived to hospital discharge; 9 horses (90%) managed conservatively survived to hospital discharge. MAIN LIMITATIONS: Follow-up was not performed for all cases following hospital discharge and some data were incompletely recorded in hospital files. CONCLUSIONS: Previously stated causative factors for AAD were not consistent features in the present study. Surgical site infection following laparotomy and pregnant or early post-partum mares may be important risk factors for AAD and warrant further investigation.

Ex vivo comparison of barbed sutures for pelvic flexure enterotomy in horses.

OBJECTIVE: To evaluate two different barbed sutures for closure of pelvic flexure enterotomies and compare results achieved with two previously described closure techniques. STUDY DESIGN: Ex vivo. SAMPLE POPULATION: Twenty-four fresh cadaver adult equine large colons. METHODS: Cadavers were randomly assigned to four closure groups (n = 6 each group): single-layer absorbable suture, double-layer absorbable suture, single-layer unidirectional barbed suture, or single-layer bidirectional barbed suture. Construction time, luminal reduction (percentage), bursting pressure, and method of failure were measured. Cost, leakage, exposed suture, and general appearance were recorded. Comparisons were performed with one-way analysis of variance and post hoc Bonferroni test (P < .05). RESULTS: Double-layer absorbable closure had the highest bursting pressure (mean = 178.5 mm Hg, SD = 9.79, P < .001) but took more time (P = .001) compared with all other groups. The construction time of both barbed suture closures did not differ from the single-layer closure (P > .06). Bursting strengths of both unidirectional (mean = 91.6 mm Hg, SD = 5.57) and bidirectional (mean = 87.5 mm Hg, SD = 8.69) barbed sutures were lower (P > .006 for both) than those of both single- (mean = 117.6 mm Hg, SD = 11.69) and double-layer (mean = 178.5 mm Hg, SD = 9.79) closures. Unidirectional barbed suture closure had a reduction in lumen diameter (P = .004) compared with bidirectional and single-layer closures. CONCLUSION: Enterotomy closures with the two different barbed suture patterns were comparable in bursting strength and construction time. However, the barbed suture patterns had lower bursting strength compared with traditional single- and double-layer closures. Unidirectional barbed suture closure also reduced lumen diameter. CLINICAL SIGNIFICANCE: Closure of a large colon enterotomy with barbed suture patterns may be less secure than single- and double-layer suture closure.

Identification of plasminogen activator inhibitor-2 as a gastrin-regulated gene: Role of Rho GTPase and menin.

BACKGROUND & AIMS: The gastric hormone gastrin regulates acid secretion, gene expression, and the functional development and cellular composition of the gastric mucosa. Using a gene array, we sought to identify major, novel, gastrin-regulated genes. METHODS: A cancer gene array was probed with samples from the gastric cancer cell line AGS, expressing the gastrin-cholecystokinin(B) receptor and stimulated with gastrin. The expression of gastrin-regulated genes was further characterized by Western blots and enzyme-linked immunosorbent assay in tissue and blood of hypergastrinemic patients. Gene expression was studied using promoter-luciferase reporter constructs. RESULTS: Plasminogen activator inhibitor 2 (PAI-2) was identified as a major, previously unknown target of gastrin in the gastric cancer cell line AGS. The relevance was confirmed by showing elevated tissue and plasma PAI-2 in hypergastrinemic patients (pernicious anemia and multiple endocrine neoplasia type 1). PAI-2 promoter-luciferase constructs showed that gastrin stimulated expression via pathways involving Galpha and Gbetagamma subunits, protein kinase C, RhoA, and the transcription factors CREB and AP1. The tumor suppressor menin inhibited transcription. In addition, gastrin stimulated expression in adjacent cells via a paracrine mechanism involving protein kinase C and RhoA but not CREB. CONCLUSIONS: A gene array showed PAI-2 to be a novel gastrin-regulated gene, stimulated in part through CREB and AP-1 and inhibited by the tumor suppressor menin.

Traffic dynamics of the leaf-cutting ant, Atta cephalotes.

Colonies of Atta cephalotes (Myrmicinae: Formicidae) construct cleared paths between their nest and the vegetation sources at which they harvest leaf tissue. Here, we employ ideas from traffic engineering to study streams of laden and unladen ants on these paths. The relationship between average traffic speed and the concentration of workers on the road surface follows a relationship similar to what is expected by analogy to fluid dynamics. Although the traffic is composed of eusocial organisms with a common interest in group success, the coarse-grained behavior of Atta traffic displays little more coordination than a moving fluid. The relationship between speed and concentration implies that maximum flow rates (which are likely to be closely tied to colony-level rates of resource acquisition) occur at a relatively high concentration that keeps individual speeds well below their "free flow" maximum. We predict that this optimal concentration will characterize peak traffic throughout a trail network, and we propose a simple behavioral mechanism that would allow trails to be cleared to the correct width to provide the optimal concentration. Collisions (including encounters for antennation) are common in leaf-cutting ant traffic because traffic is not segregated into unidirectional streams. Nonetheless, we find a counterintuitive suggestion that flow rates (with concentration differences statistically removed) are higher when traffic is near a 50:50 mix of outbound and returning ants than when it contains majority flows in a single direction. Mixed-direction traffic may help disperse laden ants with reduced agility, thereby preventing inhomogeneities in the traffic stream that could clog the trail.