Panmictic and Clonal Evolution on a Single Patchy Resource Produces Polymorphic Foraging Guilds.

We develop a stochastic, agent-based model to study how genetic traits and experiential changes in the state of agents and available resources influence individuals' foraging and movement behaviors. These behaviors are manifest as decisions on when to stay and exploit a current resource patch or move to a particular neighboring patch, based on information of the resource qualities of the patches and the anticipated level of intraspecific competition within patches. We use a genetic algorithm approach and an individual's biomass as a fitness surrogate to explore the foraging strategy diversity of evolving guilds under clonal versus hermaphroditic sexual reproduction. We first present the resource exploitation processes, movement on cellular arrays, and genetic algorithm components of the model. We then discuss their implementation on the Nova software platform. This platform seamlessly combines the dynamical systems modeling of consumer-resource interactions with agent-based modeling of individuals moving over a landscapes, using an architecture that lays transparent the following four hierarchical simulation levels: 1.) within-patch consumer-resource dynamics, 2.) within-generation movement and competition mitigation processes, 3.) across-generation evolutionary processes, and 4.) multiple runs to generate the statistics needed for comparative analyses. The focus of our analysis is on the question of how the biomass production efficiency and the diversity of guilds of foraging strategy types, exploiting resources over a patchy landscape, evolve under clonal versus random hermaphroditic sexual reproduction. Our results indicate greater biomass production efficiency under clonal reproduction only at higher population densities, and demonstrate that polymorphisms evolve and are maintained under random mating systems. The latter result questions the notion that some type of associative mating structure is needed to maintain genetic polymorphisms among individuals exploiting a common patchy resource on an otherwise spatially homogeneous landscape.

Can we predict which patients are likely to develop severe complications following reconstruction for osteoradionecrosis?

High morbidity has been reported for free vascularised reconstruction for osteoradionecrosis (ORN) and there are no apparent risk factors. A single nucleotide polymorphism in the transforming growth factor beta 1 gene (TGF-ß1) has been implicated in the cause of ORN and may also predict these complications. We studied a series of 30 consecutive patients who had had reconstruction for severe ORN with free tissue transfer in relation to their outcomes and complications for a number of risk factors including TFG-ß1 genotype, age, sex, comorbidities, site and stage of tumour, type of initial operation, and dose of radiotherapy or chemoradiotherapy. Two patients died and 2 flaps failed. Using the Clavien-Dindo classification, 16 patients developed grade III complications and 6 grade II. Median (IQR) duration of inpatient stay was 19.5 (12-25) days and the median (IQR) duration of outpatient treatment was 6 (4-11) weeks. No specific risk factors for postoperative complications were identified. In view of the severity and unpredictability of the complications, careful preoperative counselling of patients is essential.

Trismus following radiotherapy to the head and neck is likely to have distinct genotype dependent cause.

OBJECTIVES: Trismus frequently occurs as a consequence of radiotherapy or chemo-radiotherapy to the head and neck, with a loss of function that can reduce the overall quality of life. Radiation can trigger an intense fibrosis within the masticatory muscles and transforming growth factor beta 1 (TGF ß1) is involved in this process. As in other tissues the degree of fibrosis may be related to a single nucleotide polymorphism; C-T at position -509 in the TGF ß1 gene. MATERIALS AND METHODS: Trismus was measured in 62 patients before and after radiotherapy or chemoradiotherapy, blood was taken for DNA extraction, and genotype analysis of the TGF ß1 gene. Trismus was analysed against, patient age, sex, tumour site and stage, radiotherapy, and chemotherapy. RESULTS AND CONCLUSIONS: After radiotherapy or chemo-radiotherapy the reduction in mouth opening was shown to be significantly related to the presence of the T allele (p<0.001), with patients homozygous the most likely to be severely affected. No other patient, tumour or treatment factors were significant. Hence the TGF ß1 genotype is likely to be an important predictor of the degree of post radiotherapy or chemo-radiotherapy trismus.

Home range plus: a space-time characterization of movement over real landscapes.

BACKGROUND: Advances in GPS technology have created both opportunities in ecology as well as a need for analytical tools that can deal with the growing volume of data and ancillary variables associated with each location. RESULTS: We present T-LoCoH, a home range construction algorithm that incorporates time into the construction and aggregation of local kernels. Time is integrated with Euclidean space using an adaptive scaling of the individual's characteristic velocity, enabling the construction of utilization distributions that capture temporal partitions of space as well as contours that differentiate internal space based on movement phase and time-use metrics. We test T-LoCoH against a simulated dataset and provide illustrative examples from a GPS dataset from springbok in Namibia. CONCLUSIONS: The incorporation of time into home range construction expands the concept of utilization distributions beyond the traditional density gradient to spatial models of movement and time, opening the door to new applications in movement ecology.

Sentinel lymph node biopsy for T1/T2 oral cavity squamous cell carcinoma--a prospective case series.

BACKGROUND: Sentinel lymph node biopsy (SLNB) is an established technique in breast and melanoma surgery and is gaining acceptance in the management of oral cavity squamous cell carcinoma. We report a single institution's experience of SLNB between 2006 and 2010. METHODS: Prospective consecutive cohort study of 59 patients recruited between 2006 and 2010. All patients underwent SLNB with preoperative lymphoscintigraphy, intraoperative blue dye, and handheld gamma probe. Sentinel nodes were evaluated with step-serial sectioning and immunohistochemistry. Endpoints included: overall survival (OS), disease-specific survival (DSS), local recurrence-free survival (LRFS), and regional recurrence-free survival (RRFS). RESULTS: A total of 59 patients (36 male and 23 female) were operated on. Of these, 42 patients (71%) were pT1 and 17 patients (29%) were pT2. In two patients the sentinel node was not identified and proceeded to elective neck dissection. A total of 150 nodes were harvested from the remaining 57 patients of which 21 nodes were positive in 17 patients; three patients had positive contralateral nodes. The 2-year OS, DSS, LRFS, and RRFS for the SLNB negative patients were 97.5, 100, 95.8, and 95.8% and for the SLNB positive patients 68.2, 81.8, 83.9, and 100% respectively. Only OS and DSS approached statistical significance with P values of 0.07 and 0.06. CONCLUSIONS: SLNB is a safe and accurate diagnostic technique for staging the neck with a negative predictive value in our series of 97.5%. Furthermore, in our series three patients (5%) had positive contralateral neck drainage that would have been missed by conventional ipsilateral neck dissection.

Osteoradionecrosis in head-and-neck cancer has a distinct genotype-dependent cause.

PURPOSE: We performed a case-control study to establish whether the development of osteoradionecrosis (ORN) was related to a variant allele substituting T for C at -509 of the transforming growth factor-ß1 gene (TGF-ß1). PATIENTS AND METHODS: A total of 140 patients, 39 with and 101 without ORN, who underwent radiotherapy for head-and-neck cancer with a minimum of 2 years follow-up, were studied. None of the patients had clinical evidence of recurrence at this time. DNA extracted from blood was genotyped for the -509 C-T variant allele of the TGF-ß1 gene. RESULTS: There were no significant differences in patient, cancer treatment, or tumor characteristics between the two groups. Of the 39 patients who developed ORN, 9 were homozygous for the common CC allele, 19 were heterozygous, and 11 were homozygous for the rare TT genotype. Of the 101 patients without ORN, the distribution was 56 (CC), 33 (CT), and 12 (TT). The difference in distribution was significant, giving an increased risk of ORN of 5.7 (95% CI, 1.7-19.2) for homozygote TT patients (p = 0.001) and 3.6 (95% CI, 1.3-10.0) for heterozygotes (p = 0.004) when compared with patients with the CC genotype. Postradiotherapy dentoalveolar surgery preceding the development of ORN was associated with the CC genotype (p = 0.02). CONCLUSIONS: Our findings support the postulate that the development of ORN is related to the presence of the T variant allele at -509 within the TGF-ß1 gene.

LoCoH: nonparameteric kernel methods for constructing home ranges and utilization distributions.

Parametric kernel methods currently dominate the literature regarding the construction of animal home ranges (HRs) and utilization distributions (UDs). These methods frequently fail to capture the kinds of hard boundaries common to many natural systems. Recently a local convex hull (LoCoH) nonparametric kernel method, which generalizes the minimum convex polygon (MCP) method, was shown to be more appropriate than parametric kernel methods for constructing HRs and UDs, because of its ability to identify hard boundaries (e.g., rivers, cliff edges) and convergence to the true distribution as sample size increases. Here we extend the LoCoH in two ways: "fixed sphere-of-influence," or r-LoCoH (kernels constructed from all points within a fixed radius r of each reference point), and an "adaptive sphere-of-influence," or a-LoCoH (kernels constructed from all points within a radius a such that the distances of all points within the radius to the reference point sum to a value less than or equal to a), and compare them to the original "fixed-number-of-points," or k-LoCoH (all kernels constructed from k-1 nearest neighbors of root points). We also compare these nonparametric LoCoH to parametric kernel methods using manufactured data and data collected from GPS collars on African buffalo in the Kruger National Park, South Africa. Our results demonstrate that LoCoH methods are superior to parametric kernel methods in estimating areas used by animals, excluding unused areas (holes) and, generally, in constructing UDs and HRs arising from the movement of animals influenced by hard boundaries and irregular structures (e.g., rocky outcrops). We also demonstrate that a-LoCoH is generally superior to k- and r-LoCoH (with software for all three methods available at http://locoh.cnr.berkeley.edu).

Free vascularised iliac crest graft: an audit of 26 consecutive cases.

Over an 18 month period 26 vascularised myo-osseus, and one myo-osseus-cutaneous iliac crest flaps were used to reconstruct 18 mandibular and eight maxillary defects. During the operation one flap failed to reperfuse and was removed. Postoperatively three patients were returned to theatre for appraisal and reanastomoses, which in two cases involved thrombolysis. In all three salvage was deemed successful but in all there was partial muscle necrosis. There were 10 cases of anaesthesia of the skin supplied by the lateral cutaneous nerve of the thigh, three incisional hernias, one wound dehiscence in the thigh, two oronasal fistulas, one wound dehiscence in the neck, one infection by methicillin resistant Staphylococcus aureus in the thigh, and two long-term and one medium-term disturbances of gait. Complications were graded as severe (4%), intermediate (27%), and minor (46%).