Aim
Studies on latitudinal patterns in plant defence have traditionally overlooked the potential effect that resource availability may have in shaping plant defence. Likewise, latitudinal patterns of ...tolerance traits have rarely been studied, yet they can be a critical component of plant defence. Therefore, the aim of our study was to examine latitudinal variation in the production of tolerance and resistance traits against herbivory along a latitudinal range and a natural gradient of resource availability from upwelling conditions.
Location
North America (Canada, USA, Mexico).
Time period
Summer months of 2015.
Major taxa used
The seagrass Zostera marina.
Methods
We conducted experiments simulating macroherbivore (e.g., bird, fish) damage on the seagrass Z. marina at 10 sites across the Eastern Pacific coast (Canada–Mexico) and Quebec and analysed several traits related to resistance and tolerance strategies against herbivory. In addition, we examined the effects of potential seagrass changes in defence strategies by performing a series of feeding experiments with mesoherbivores in a subset of sites.
Results
We found that eelgrass resistance defences did not follow a linear latitudinal pattern but rather followed a bell‐shaped curve which correlated with bottom‐up control. In sites with higher nutrient availability, plants allocated resources to tolerance strategies and had lower resistance traits. Furthermore, seagrasses did not respond linearly to increased herbivory pressure; while they tolerated moderate levels of herbivory, they underwent a significant reduction in tolerance and resistance under high herbivory levels, which also made them more susceptible to consumers in feeding experiments.
Main conclusions
Our results highlight the importance that nutrient availability has in shaping latitudinal patterns of plant defence against herbivory and show how these defences may not respond linearly to increased herbivory pressure in seagrasses.
Osteoarthritis of the hip and knee is a leading cause of functional disability and compromised quality of life in older patients and a significant public health issue. Emerging research shows sex and ...gender differences in osteoarthritis which, to date, may not be appreciated by the orthopedic community. This article discusses sex and gender differences in osteoarthritis with a focus on disease involving the hip and knee. Understanding what we know (and do not know) about sex and gender differences in this disorder is critical to improving quality of care for our patients.
The current standard of practice for the detection of osseous metastatic disease is the conventional bone scan of the entire body using technetium-99m methylene diphosphonate (Tc-99m MDP). Although ...Tc-99m MDP scintigraphy is sensitive for the detection of advanced skeletal metastatic lesions, early involvement may be missed because this technique relies on the identification of the osteoblastic reaction of the involved bone rather than the detection the tumor itself. Positron emission tomography (PET) has proven to be the gold standard in metabolic imaging. Fluorine -18 deoxyglucose (FDG) provides a means of quantitating the glucose metabolism, with the amount of tracer accumulation reflecting the glucose metabolism: high-grade malignancies tend to have higher rates of glycolysis than do low-grade malignancies and benign lesions; therefore, high-grade malignancies have greater uptake of FDG than that of low-grade or benign lesions. Positron emission tomography has been shown to be superior to scintigraphy in the detection of metastases because it detects the presence of tumor directly by metabolic activity, rather than indirectly by showing tumor involvement due to increased bone mineral turnover. This has allowed the detection of metastatic foci earlier with PET than with bone scintigraphy. Although the spectrum of PET applications is unknown, it now is approved for the diagnosis, staging and restaging of many common malignancies and has shown efficacy for the detection of osseous metastasis from several malignancies including lung carcinoma, breast carcinoma, and lymphoma.
Reconstruction after the resection of pelvic tumors is a major challenge. It depends on many factors such as age, activity level, type of tumor, its adjuvant treatment, and the extent of the disease. ...The purpose of the current study was to analyze the functional and oncologic outcomes of patients who had an iliofemoral arthrodesis after resection of a pelvic sarcoma. Between 1981 and 1999, 20 males and 12 females with a mean age of 39.9 years (range, 10-71 years) had an iliofemoral arthrodesis, either as a solid fusion or primary pseudarthrosis, at one institution. The functional outcome was evaluated using the Musculoskeletal Tumor Society and the Toronto Extremity Salvage scores. At a mean followup of 97 months (range, 14-226 months), 15 of 32 patients were alive, all without disease. The radiographic union rate was 86%. The mean overall Musculoskeletal Tumor Society and Toronto Extremity Salvage scores were 64% and 48%, respectively. Patients with a primary solid fusion did functionally better compared with patients who had pseudarthrosis (Toronto Extremity Salvage Score, 76%; Musculoskeletal Tumor Society Score, 71% versus Toronto Extremity Salvage Score, 52%; Musculoskeletal Tumor Society Score, 25%). Biomechanical analysis showed that the loss of motion in the hip is well-compensated. The authors conclude from this series that iliofemoral reconstruction after resection of a pelvic sarcoma provides acceptable and durable long-term results, not only from the oncologic, but also from the functional perspective.
Many early metal-on-polyethylene hip resurfacing arthroplasty designs were abandoned after reports of high short-term and midterm failure rates. To investigate factors associated with failure, we ...retrospectively reviewed our experience with early-design hip resurfacing implants in 75 patients during a 25-year period (median followup, 7.9 years; range, 0.1–25.2 years). Implant failure was defined as revision for any reason. One of 75 patients was lost to followup. The estimated rate of implant survival was 73% at 5 years, 34% at 10 years, 27% at 15 years, 12% at 20 years, and 8% at 25 years. Of the many clinical and radiographic factors considered, only age, implant type, and gender were associated with implant survival independent of other variables considered. Hip resurfacing arthroplasty showed poor overall long-term survival in this series. Particular attention should be paid to the identified risk factors as long-term followup data become available for modern designs.
Level of Evidence:
Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
Functional outcomes of patients with arthrodesis after resection of a shoulder girdle neoplasm are only sparsely reported. Fusion of the shoulder can be done as a primary reconstruction or ...secondarily for salvage of a failed limb-sparing procedure. We retrospectively reviewed 21 patients at a mean followup of 11 years. In eight patients, arthrodesis was done as the primary reconstruction and in 13 patients as the secondary procedure. There were no local recurrences, and no patient had metastatic disease develop. The overall Toronto extremity salvage and Musculoskeletal Tumor Society scores were 81% (range, 46-97) and 23 points (range, 17-26), respectively. There was no difference with respect to function between patients who had their arthrodesis as a primary or secondary procedure. Eight of 21 patients (43%) had a complication that required major surgical intervention. Shoulder arthrodesis as a limb salvage procedure after tumor resection provides good function independent of whether the procedure is done primarily or secondarily. Because of the high complication rate, future efforts must be directed at surgical methods to decrease such complications.
Therapeutic study, Level IV (case series--no, or historical control group). See the Guidelines to Authors for a complete description of levels of evidence.
While considerable evidence exists of biogeographic patterns in the intensity of species interactions, the influence of these patterns on variation in community structure is less clear. Studying how ...the distributions of traits in communities vary along global gradients can inform how variation in interactions and other factors contribute to the process of community assembly. Using a model selection approach on measures of trait dispersion in crustaceans associated with eelgrass (
) spanning 30° of latitude in two oceans, we found that dispersion strongly increased with increasing predation and decreasing latitude. Ocean and epiphyte load appeared as secondary predictors; Pacific communities were more overdispersed while Atlantic communities were more clustered, and increasing epiphytes were associated with increased clustering. By examining how species interactions and environmental filters influence community structure across biogeographic regions, we demonstrate how both latitudinal variation in species interactions and historical contingency shape these responses. Community trait distributions have implications for ecosystem stability and functioning, and integrating large-scale observations of environmental filters, species interactions and traits can help us predict how communities may respond to environmental change.
A laboratory evaluation was undertaken to assess the shoulder range of motion and distal strength after oncologic resection and reconstruction involving the shoulder joint and to compare these ...functional parameters based on potentially important variables. Inclusion in the study was limited to 32 patients with bone tumors of the proximal humerus or scapula treated surgically by resection of the shoulder joint including the proximal humerus from 1976 through 1992. Active shoulder range of motion and isometric elbow extension and forearm supination strength are significantly less after surgery in patients with greater amounts of bony resection and with resection of the deltoid. Patients who had a modified Tikhoff-Linberg resection were able to achieve 10 degrees to 15 degrees greater shoulder motion in each direction than were patients who had the classic procedure including complete scapulectomy. However, elbow flexion and extension strength and forearm pronation strength were greater for the patients with the classic resection. Osteoarticular allografts as a reconstructive alternative provide as a group the best shoulder motion and overall distal upper extremity strength, but these reconstructions were performed only when the rotator cuff muscles and deltoid were able to be reconstructed. Diminishing elbow strength was seen with longer followup in the patients with osteoarticular reconstructions, corresponding temporally to subchondral collapse observed on radiographs. Range of shoulder motion except rotation was just as good for allograft vascularized fibular arthrodeses as for the osteoarticular allografts, but strength was significantly less with the arthrodeses.
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