Conservation genomics of an endangered montane amphibian reveals low population structure, low genomic diversity and selection pressure from disease.

Wildlife diseases are a major global threat to biodiversity. Boreal toads (Anaxyrus [Bufo] boreas) are a state-endangered species in the southern Rocky Mountains of Colorado and New Mexico, and a species of concern in Wyoming, largely due to lethal skin infections caused by the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). We performed conservation and landscape genomic analyses using single nucleotide polymorphisms from double-digest, restriction site-associated DNA sequencing in combination with the development of the first boreal toad (and first North American toad) reference genome to investigate population structure, genomic diversity, landscape connectivity and adaptive divergence. Genomic diversity (π = 0.00034-0.00040) and effective population sizes (Ne = 8.9-38.4) were low, likely due to post-Pleistocene founder effects and Bd-related population crashes over the last three decades. Population structure was also low, likely due to formerly high connectivity among a higher density of geographically proximate populations. Boreal toad gene flow was facilitated by low precipitation, cold minimum temperatures, less tree canopy, low heat load and less urbanization. We found >8X more putatively adaptive loci related to Bd intensity than to all other environmental factors combined, and evidence for genes under selection related to immune response, heart development and regulation and skin function. These data suggest boreal toads in habitats with Bd have experienced stronger selection pressure from disease than from other, broad-scale environmental variations. These findings can be used by managers to conserve and recover the species through actions including reintroduction and supplementation of populations that have declined due to Bd.

The effect of haemorrhagic shock and resuscitation on fracture healing in a rabbit model: an animal study.

Aims: Little is known about the effect of haemorrhagic shock and resuscitation on fracture healing. This study used a rabbit model with a femoral osteotomy and fixation to examine this relationship. Materials and Methods: A total of 18 male New Zealand white rabbits underwent femoral osteotomy with intramedullary fixation with 'shock' (n = 9) and control (n = 9) groups. Shock was induced in the study group by removal of 35% of the total blood volume 45 minutes before resuscitation with blood and crystalloid. Fracture healing was monitored for eight weeks using serum markers of healing and radiographs. Results: Four animals were excluded due to postoperative complications. The serum concentration of osteocalcin was significantly elevated in the shock group postoperatively (p < 0.0001). There were otherwise no differences with regard to serum markers of bone healing. The callus index was consistently increased in the shock group on anteroposterior (p = 0.0069) and lateral (p = 0.0165) radiographs from three weeks postoperatively. The control group showed an earlier decrease of callus index. Radiographic scores were significantly greater in the control group (p = 0.0025). Conclusion: In a rabbit femoral osteotomy model with intramedullary fixation, haemorrhagic shock and resuscitation produced larger callus but with evidence of delayed remodelling. Cite this article: Bone Joint J 2018;100-B:1234-40.

Preventable mortality in geriatric hip fracture inpatients.

There is a high rate of mortality in elderly patients who sustain a fracture of the hip. We aimed to determine the rate of preventable mortality and errors during the management of these patients. A 12 month prospective study was performed on patients aged > 65 years who had sustained a fracture of the hip. This was conducted at a Level 1 Trauma Centre with no orthogeriatric service. A multidisciplinary review of the medical records by four specialists was performed to analyse errors of management and elements of preventable mortality. During 2011, there were 437 patients aged > 65 years admitted with a fracture of the hip (85 years (66 to 99)) and 20 died while in hospital (86.3 years (67 to 96)). A total of 152 errors were identified in the 80 individual reviews of the 20 deaths. A total of 99 errors (65%) were thought to have at least a moderate effect on death; 45 reviews considering death (57%) were thought to have potentially been preventable. Agreement between the panel of reviewers on the preventability of death was fair. A larger-scale assessment of preventable mortality in elderly patients who sustain a fracture of the hip is required. Multidisciplinary review panels could be considered as part of the quality assurance process in the management of these patients.

The accuracy of three-dimensional model generation. What makes it accurate to be used for surgical planning?

Computerized treatment planning is routinely used in cranio-maxillofacial applications. For these therapeutic applications, it is of critical importance to have a precise model of the structures in question. Improved imaging techniques and advances in software engineering have moved three-dimensional (3D) computer models from the research and development area into routine clinical application. The importance of high-resolution source imaging is well understood by surgeons. The influence of image processing is poorly understood in the surgical community and we hypothesize that this may be a source of significant error. We evaluated the workflow for creating a virtual model using computed tomography data, and the impact that image processing decisions have on final virtual model accuracy. We chose to create a model of the dental surface since it is one of the most complex structures in the area. Individual image processing steps are explained and the magnitudes of their influence on model quality are demonstrated and compared. This study demonstrates that inappropriate image processing can introduce errors of similar magnitude as the use of inadequate source data. Finally, the study shows that errors caused by inappropriate image processing amplify the inaccuracies of low-resolution source imagery and eliminate the benefits of high-resolution source imaging.

Physiological assessment of the polytrauma patient: initial and secondary surgeries.

The timing of fracture fixation in polytrauma patients has been debated for a long time. The decision between DCO (damage control orthopaedics) and ETC (early total care) is a difficult dilemma. Overzealous ETC in haemodynamically compromised patients with significant chest and head injuries can be detrimental. It has been shown, however, that early fracture fixation has a trend towards better outcome in patients with less severe injuries. Delaying all orthopaedic surgery in critically injured patients can be a safe alternative, but has several disadvantages like longer ICU stay and septic complications. The literature shows equivocal evidence for both settings. This article will summarize the historical background and controversies regarding patient assessment and decision making during the treatment of polytrauma patients. It will also give guidance for choosing DCO versus ETC in the clinical setting.

The effect of metiamide, an H2-receptor antagonist, in the prevention of experimental stress ulcers.

Because of evidence that Metiamide, an H2-receptor antagonist, strongly inhibits gastric acid secretion, the present study was designed to test the hypothesis that Metiamide will prevent bile salt-induced stress ulcers during hemorrhagic shock. Forty dogs were bled and maintained for 4 1/2 hr at a mean blood pressure of 40 to 50 mm Hg. In group A, 10 dogs received 300 mg of Metiamide orally 45 min before bleeding and 10 dogs received normal saline. The pylorus was occluded before bleeding and 100 ml of 15 mM bile salt were instilled into the stomach and aspirated at the end of 4 1/2 hr. At the time the animal was killed after 48 hr, no ulcers were seen in the stomachs of dogs treated with Metiamide. Sixty per cent of the dogs in the untreated group developed multiple gross ulcers. In group B the effect of Metiamide on the disappearance rate of H+ ion was measured by instillation of 50 mM HCl + 15 mM bile acid. No difference was noted in the rate of H+ ion disappearance between Metiamide-treated and control dogs. Also, in 5 normotensive dogs the rate of H+ ion disappearance was measured before and after treatment with Metiamide, and the loss of H+ was identical for both periods. Metiamide was effective in preventing stress ulcer in this experimental model. The protective effect of Metiamide is probably due to its inhibitory effect of H+ ion secretion.

Treatment of reflux esophagitis resulting in massive esophageal bleeding.

The complications that occur secondary to sliding hiatal hernia are reflux esophagitis with ulceration, stricture formation, and hemorrhage. We have treated seven patients for massive esophageal bleeding secondary to reflux esophagitis. All had endoscopic evidence of reflux esophagitis and a negative work-up for other sources of bleeding. All underwent Nissen fundoplication as the only mode of therapy for the bleeding esophagitis. No patient has bled again; healing of the esophagitis was evident six weeks after operation, as observed by gastrointestinal endoscopy. This operation prevents reflux, has minimal side-effects, and gives consistent results in the hands of the average trained gastrointestinal surgeon.