The Learning Curve of Third-Generation Percutaneous Chevron and Akin Osteotomy (PECA) for Hallux Valgus.

The learning curve to reach technical proficiency for third-generation percutaneous or minimally invasive chevron and Akin osteotomies (PECA/MICA) is recognized to be steep however it is poorly defined in the literature. This study is a retrospective review of the first 58 consecutive PECA cases of a single surgeon. The primary outcome was the number of cases required to reach technical proficiency as defined by the operation time. Secondary outcomes included radiation exposure, radiographic deformity correction, and complication rates. Between November 2017 and March 2019, 61 consecutive PECA cases were performed with outcome data available for 58 of these (95%). Technical proficiency was reached after 38 cases. Operation time and radiation exposure significantly decreased after this transition point (p < .05). There was no difference in complication rate or radiographic deformity correction regardless of position along the learning curve (p > .05). In conclusion, the mean number of cases required to reach technical proficiency in third-generation PECA is 38 cases. The complication rate does not correlate to the number of cases performed, therefore surgeons interested in learning minimally invasive surgery can be reassured that there is unlikely to be an additional risk of harm to a patient during the learning curve.

Convergence of marine megafauna movement patterns in coastal and open oceans.

The extent of increasing anthropogenic impacts on large marine vertebrates partly depends on the animals' movement patterns. Effective conservation requires identification of the key drivers of movement including intrinsic properties and extrinsic constraints associated with the dynamic nature of the environments the animals inhabit. However, the relative importance of intrinsic versus extrinsic factors remains elusive. We analyze a global dataset of ∼2.8 million locations from >2,600 tracked individuals across 50 marine vertebrates evolutionarily separated by millions of years and using different locomotion modes (fly, swim, walk/paddle). Strikingly, movement patterns show a remarkable convergence, being strongly conserved across species and independent of body length and mass, despite these traits ranging over 10 orders of magnitude among the species studied. This represents a fundamental difference between marine and terrestrial vertebrates not previously identified, likely linked to the reduced costs of locomotion in water. Movement patterns were primarily explained by the interaction between species-specific traits and the habitat(s) they move through, resulting in complex movement patterns when moving close to coasts compared with more predictable patterns when moving in open oceans. This distinct difference may be associated with greater complexity within coastal microhabitats, highlighting a critical role of preferred habitat in shaping marine vertebrate global movements. Efforts to develop understanding of the characteristics of vertebrate movement should consider the habitat(s) through which they move to identify how movement patterns will alter with forecasted severe ocean changes, such as reduced Arctic sea ice cover, sea level rise, and declining oxygen content.

Foraging strategies of a generalist marine predator inhabiting a dynamic environment.

Intraspecific variability is increasingly recognized as an important component of foraging behavior that can have implications for both population and community dynamics. We used an individual-level approach to describe the foraging behavior of an abundant, generalist predator that inhabits a dynamic marine ecosystem, focusing specifically on the different foraging strategies used by individuals in the same demographic group. We collected data on movements and diving behavior of adult female California sea lions (Zalophus californianus) across multiple foraging trips to sea. Sea lions (n = 35) used one of three foraging strategies that primarily differed in their oceanic zone and dive depth: a shallow, epipelagic strategy, a mixed epipelagic/benthic strategy, and a deep-diving strategy. Individuals varied in their degree of fidelity to a given strategy, with 66 % of sea lions using only one strategy on all or most of their foraging trips across the two-month tracking period. All foraging strategies were present in each of the sampling years, but there were inter-annual differences in the population-level importance of each strategy that may reflect changes in prey availability. Deep-diving sea lions traveled shorter distances and spent a greater proportion of time at the rookery than sea lions using the other two strategies, which may have energetic and reproductive implications. These results highlight the importance of an individual-based approach in describing the foraging behavior of female California sea lions and understanding how they respond to the seasonal and annual changes in prey availability that characterize the California Current System.

Condition and mass impact oxygen stores and dive duration in adult female northern elephant seals.

The range of foraging behaviors available to deep-diving, air-breathing marine vertebrates is constrained by their physiological capacity to breath-hold dive. We measured body oxygen stores (blood volume and muscle myoglobin) and diving behavior in adult female northern elephant seals, Mirounga angustirostris, to investigate age-related effects on diving performance. Blood volume averaged 74.4+/-17.0 liters in female elephant seals or 20.2+/-2.0% of body mass. Plasma volume averaged 32.2+/-7.8 liters or 8.7+/-0.7% of body mass. Absolute plasma volume and blood volume increased independently with mass and age. Hematocrit decreased weakly with mass but did not vary with age. Muscle myoglobin concentration, while higher than previously reported (7.4+/-0.7 g%), did not vary with mass or age. Pregnancy status did not influence blood volume. Mean dive duration, a proxy for physiological demand, increased as a function of how long seals had been at sea, followed by mass and hematocrit. Strong effects of female body mass (range, 218-600 kg) on dive duration, which were independent of oxygen stores, suggest that larger females had lower diving metabolic rates. A tendency for dives to exceed calculated aerobic limits occurred more frequently later in the at-sea migration. Our data suggest that individual physiological state variables and condition interact to determine breath-hold ability and that both should be considered in life-history studies of foraging behavior.

Measurements of foraging success in a highly pelagic marine predator, the northern elephant seal.

1. Identification of foraging behaviour and the ability to assess foraging success is critical to understanding individual and between-species variation in habitat use and foraging ecology. For pelagic predators, behaviour-dependent foraging metrics are commonly used to identify important foraging areas, yet few of these metrics have been validated. 2. Using the northern elephant seal as a model species, we validated the use of a behaviour-independent measure of foraging success (changes in drift rate) at the scale of the entire foraging migration, and then used this to assess a variety of common foraging metrics that are based on movement patterns and dive behaviour. Transit rate consistently provided the best estimate of daily foraging success, although the addition of other metrics provides insight into different foraging behaviours or strategies. 3. While positive changes in buoyancy occurred throughout most of the migrations, implying successful feeding across much of the north Pacific, the areas of most rapid changes in buoyancy occurred along a latitudinal band (40-50° N) corresponding to a dynamic hydrographic region including Subarctic Gyre and Transition Zone waters. 4. These results support the use of transit rate as an index of foraging success: a metric that is easily derived from tracking measurements on a wide range of marine species.

Successful ex vivo renal artery reconstruction and renal autotransplantation.

BACKGROUND: The increasing experience with renal allotransplantation has led to continuing development in vascular surgical techniques. These improvements have enabled complex ex vivo renal artery surgery and renal autotransplantation to be performed. The aims of the present study were to describe the results achieved with renal autotransplantation and ex vivo renal artery reconstruction (RAR) at the Newcastle Transplant Unit, John Hunter Hospital, and to review the current indications for such surgery. METHODS: A retrospective review was performed of patients who required renal autotransplantation with or without RAR at John Hunter Hospital, between 1991 and 1999. Data were obtained from the Newcastle Transplant Unit and the Medical Record Department of John Hunter Hospital. RESULTS: Two patients required ex vivo RAR and renal autotransplantation for severe fibromuscular dysplasia (FMD) complicated by stenoses and renal artery branch aneurysms. The third patient required autotransplantation for bilateral retroperitoneal fibrosis. There was one postoperative complication of pelviureteric junction obstruction that was treated successfully with a temporary ureteric stent. All patients demonstrated normal graft function and were normotensive on follow up, which ranged from 2.5 to 5 years. CONCLUSION: The present review confirms the long-term benefits of ex vivo RAR and renal autotransplantation that have been demonstrated by previous studies. In transplant units experienced with this surgery it has been shown to be a successful and durable technique for the treatment of a variety of vascular, urologic and other diseases.

The effects of total darkness on schedule control.

The study investigated the effect of total darkness on the key pecking of pigeons under fixed-ratio, variable-ratio, fixed-interval, and variable-interval schedules of food reinforcement. Eight pigeons were divided into groups of two, with each group conditioned to peck under one of the four schedules of reinforcement. Under an ABAB procedure, all pigeons experienced alternating light and dark conditions. The house- and keylights were (a) maintained at full intensity for the first 30 one-hour sessions, (b) faded out and disconnected over Sessions 31 through 50, (c) totally illuminated for Sessions 51 to 60, and (d) disconnected again for the final 10 sessions. Responding under the ratio schedules increased from 20% to 108% in the dark and responding under the interval schedules in the dark decreased by 37% to 93%.

Effects of error and errorless discrimination acquisition on reversal learning.

The effectiveness of trial-and-error, graded-choice, and verbal-instruction procedures on the acquisition and maintenance of a two-choice simultaneous color discrimination in an intradimensional double-reversal learning situation was studied using 18 first-grade children. After acquiring a red-green discrimination during one 70-trial session, the discriminative roles of the stimuli were reversed for 30 trials, followed by a second reversal for 30 trials. Children in the graded-choice and verbal-instruction groups acquired and maintained the discriminations with fewer errors than children who learned by trial and error. The importance of the results in terms of two-stage discrimination learning theories is pointed out and similarities between errorless learning and overtraining are discussed.

Application of a graded choice procedure to obtain errorless learning in children.

A simultaneous, two-choice color discrimination was carried out with three groups of four- to seven-year-old children. For Groups I and II, the opportunity to respond to the incorrect stimulus was controlled (graded) over three different conditions. First, only a red light (S+) and its retractable bar were presented (16 trials for Group I and 316 trials for Group II). Second, a green light (S-) was added with its correlated bar retracted for 14 trials. Third, 40 trials were given with both stimuli on and their correlated retractable bars extended. The opportunity to respond to S- was not graded for Group III children. They experienced only the third condition applied to Groups I and II. Responses to S+ were reinforced for all three groups, while responses to S- were not. Children in the first two groups made from zero to three responses to S-, while the control children emitted 11 to 46 errors. The results demonstrate that fading in S- or presenting S- early in the training procedure are sufficient, but not necessary conditions for errorless learning.

A token system for a class of underachieving hyperactive children.

Using a BAB design, a token system requiring cooperative interaction was used to change the reading and vocabulary performance of an 18-member class of third-grade hyperactive boys. Four different colored tokens, which could be exchanged for 15 minutes of play on electrovideo games, were earned by successful completion of two tasks that involved learning to read and to use new vocabulary words in sentences, and two tasks in which the student served as a proctor to a student who had not yet completed those tasks. The mean number of tasks completed during the intervention periods rose to over nine times the number completed during reversal. Additionally, the average completion rate for the school district's standardized weekly reading level examinations rose from four to eight fold during the token conditions. All 18 students responded to the token program by increasing their academic performance.

Bristol index of patellar width to thickness (BIPWiT): a reproducible measure of patellar thickness from adult MRI.

BACKGROUND: The restoration of an adequate patellar thickness is a key to the successful outcome of knee arthroplasty. This study investigated the relationship between the thickness of the native patellar and medial-lateral patellar width using magnetic resonance imaging (MRI). METHODS: 75 MRI scans of young adults, with an average age of 27 (range 16-40) were studied. Exclusion criteria included a diagnosis of degenerative joint disease, patello-femoral pathology or age under 16/over 40 (170 patients). The bony thickness of the patellar, the chondral thickness and patellar width were measured, as was the location of maximal patellar thickness. Inter/intraobserver variability was calculated and correlation analysis was performed. RESULTS: We found a strong correlation between patellar width and thickness (bone plus cartilage) (Pearson 0.75, P<0.001). The mean width to thickness ratio was 1.8:1 (standard deviation 0.1, 95% confidence interval 1.78-1.83). Without cartilage the ratio was 2.16:1 (SD 0.15, 95% CI 2.11-2.21), correlation was moderate (Pearson 0.59, P<0.001). The average maximal patellar cartilage thickness was 4.1mm (SD 1.3). CONCLUSION: The strong correlation and narrow confidence intervals for the ratio of patellar width to thickness, suggest that patellar width might be used as a guide for accurate restoration of patellar thickness during total knee or patello-femoral replacement. After removing osteophytes we would recommend a ratio of 1.8:1. Further work is required to establish whether there is a relationship between anterior knee pain post total knee arthroplasty and an abnormal patellar width:thickness ratio. LEVEL OF EVIDENCE: Level III.

Studies on transcriptional regulation of the mucosal T-cell integrin alphaEbeta7 (CD103).

Integrin alphaEbeta7 is expressed almost exclusively by mucosal T cells and mucosal dendritic antigen-presenting cells (APCs) and is thought to be induced locally by transforming growth factor-beta (TGF-beta). In mice, mRNA for the alphaE subunit was found to be abundant in mucosal T cells but absent from other tissues. Exposure of a T-cell line to TGF-beta strongly up-regulated alphaE mRNA levels within 30 min, and nuclear run-on experiments established that regulation occurred at the level of transcription. The organization of the human alphaE gene and a very closely linked novel gene, ELG, was determined. The alphaE promoter was tested in T cells and fibroblasts and functioned equally well in both cell types and did not confer TGF-beta responsiveness. Regions of the promoter providing enhancer activity and phorbol 12-myristate 13-acetate (PMA) responsiveness were identified by deletion studies. DNAse 1 hypersensitivity analysis of 36 kb of the alphaE gene revealed one hypersensitive site, found only in alphaE+ cells, located near the transcription start points. These results show that, unlike the situation with other integrins, lineage specificity and cytokine responsiveness of alphaE transcription are not conferred by the proximal promoter. Specificity may depend on distant control elements that have not yet been identified.