Evaluating the relevance of surgical margins. Part one: The problems with current methodology

The goal of cancer surgery is to achieve a “clean” microscopic resection, with no residual tumour remaining in the wound. To achieve that goal, the surgeon typically incorporates a measured buffer of grossly normal tissue about the entire circumference of the tumour. Microscopic analysis of the resection boundaries is then performed to determine if all traces of the tumour have been completely removed. This analysis is thought to provide a surrogate indication as to the likelihood for that tumour to recur after surgery. However, it is recognised that tumour recurrence may not occur even when microscopic evidence of tumour has been identified at the resection margins, and recurrence can also occur when conventional histology has considered the tumour to have been completely removed. The explanations for this dichotomy are numerous and include technical and practical limitations of the processing methodology, and also several surgeon-related and tumour-related reasons. Ultimately, the inability to confidently determine when a tumour has been removed sufficiently to prevent recurrence can impact on the ability to provide owners with confident treatment advice. In this article, the authors describe the challenges with defining the true extent of the tumour margin from the perspective of the surgeon, the pathologist and the tumour. The authors also provide an analysis of why our current efforts to ensure that all traces of the local tumour have been successfully removed may provide an imperfect assessment of the risk of recurrence.     

Bandaging, endoscopy, and surgery in the emergency avian patient.

This article is divided into three parts and describes procedures used in avian medicine after initial stabilization. The first part includes the application of bandages and splints for fractures. The second part describes the use of endoscopy to examine the choana, oral cavity, trachea, and, to a lesser extent, internal organs. The last part discusses equipment required and techniques used for esophagostomy tube placement, air sac cannulation, and surgery, with approaches to the coelomic cavity and a select number of surgical procedures. This article is intended to provide the emergency animal clinician with knowledge necessary to provide basic stabilization for avian patients and knowledge of procedures that can be performed by the experienced clinician.     

Hypoxic pulmonary hypertension in the pony.

Hemodynamic measurements were made in 6 ponies at low altitude (Madison, WI, altitude, 250 m) and after 1, 2, 4, and 6 weeks at high altitude (Climax, CO, altitude, 3,400 m). The salient findings were that ponies maintain an increased heart rate and cardiac output and develop significant pulmonary hypertension at high altitude. The average control resting mean pulmonary artery pressure (BPpul) was 25.1 mm of Hg at 250 m; this value increased to 56.3 mm of Hg after 6 weeks at 3,400 m. An additional finding was that the pulmonary vascular response to acute hypoxia seemed to increase with time at high altitude.     

Molecular architecture of the multiprotein splicing factor SF3b

The splicing factor SF3b is a multiprotein complex essential for the accurate excision of introns from pre-messenger RNA. As an integral component of the U2 small nuclear ribonucleoprotein (snRNP) and the U11/U12 di-snRNP, SF3b is involved in the recognition of the pre-messenger RNA's branch site within the major and minor spliceosomes. We have determined the three-dimensional structure of the human SF3b complex by single-particle electron cryomicroscopy at a resolution of less than 10 angstroms, allowing identification of protein domains with known structural folds. The best fit of a modeled RNA-recognition motif indicates that the protein p14 is located in the central cavity of the complex. The 22 tandem helical repeats of the protein SF3b155 are located in the outer shell of the complex enclosing p14.     

Priming negatively affects feeding behaviour and aphid biomass of Rhopalosiphum padi on barley

Plants have developed numerous strategies for responding to abiotic and biotic stresses. In particular, the microbiota surrounding plants may have a positive effect on plant stress responses. One is the reaction to rhizobacteria, which can lead to induced systemic resistance. Gram-negative soil bacteria that produce N-acyl homoserine lactones (AHL), for example, Ensifer meliloti, induce a primed state in plants that is part of the inducible resistance phenomenon. Observing Rhopalosiphum padi feeding behaviour on a priming sensitive barley genotype, treated with the AHL-producing E. meliloti strain expR?+?ch, using electrical penetration graph technique showed decreased ingestion of food. Aphids appear to overcome this effect within the eight-hour observation period, possibly explaining the absence of differences of reproduction. Reproduction was observed for a period of 14 days on primed and control-treated plants. Long-term observations over a period of 40 days after aphid infestation showed a lower aphid biomass in contrast to a control group, interpreted as delayed population growth, and an increase in the biomass of barley plants. Priming-related genotypic effects of the defence response to aphids were observed, with no beneficial effects on the plant genotype when its sensitivity to priming was low. Previously, an AHL-priming sensitive barley genotype showed enhanced resistance against fungi when primed with the expR?+?ch strain of E. meliloti. The present study reports the same effect against R. padi. These findings suggest that sensitivity to AHL-priming may represent a new approach for plant breeding, targeting multiple pests in parallel by induced plant resistance.