Genetic structure of West Greenland populations of lumpfish Cyclopterus lumpus

In this study, 11 microsatellite markers were used to determine the structure of West Greenlandic lumpfish Cyclopterus lumpus populations across six spawning locations spanning >1500 km and compared with neighbouring populations in Canada and Iceland. To evaluate whether data allow for identification of origin of C. lumpus in Greenlandic waters, genetic assignment analysis was performed for 86 C. lumpus sampled on a feeding migration. Significant structuring with isolation by distance was observed in the West Greenland samples and two major subpopulations, north and south, were suggested. Based on F_ST values, closer relationships were observed between Greenland and Canada, than Greenland and Iceland. Surprisingly, the North Greenland population showed more similarities with Canadian samples, than did the geographically closer south-west Greenland population. Origin could be assigned for a high proportion of non-spawning fish and demonstrated a marked east-west spatial separation of fish of Greenlandic and Icelandic genotypes.

Unmanned aerial platform-based multi-spectral imaging for field phenotyping of maize

BACKGROUND

Recent developments in unmanned aerial platforms (UAP) have provided research opportunities in assessing land allocation and crop physiological traits, including response to abiotic and biotic stresses. UAP-based remote sensing can be used to rapidly and cost-effectively phenotype large numbers of plots and field trials in a dynamic way using time series. This is anticipated to have tremendous implications for progress in crop genetic improvement.

RESULTS

We present the use of a UAP equipped with sensors for multispectral imaging in spatial field variability assessment and phenotyping for low-nitrogen (low-N) stress tolerance in maize. Multispectral aerial images were used to (1) characterize experimental fields for spatial soil-nitrogen variability and (2) derive indices for crop performance under low-N stress. Overall, results showed that the aerial platform enables to effectively characterize spatial field variation and assess crop performance under low-N stress. The Normalized Difference Vegetation Index (NDVI) data derived from spectral imaging presented a strong correlation with ground-measured NDVI, crop senescence index and grain yield.

CONCLUSION

This work suggests that the aerial sensing platform designed for phenotyping studies has the potential to effectively assist in crop genetic improvement against abiotic stresses like low-N provided that sensors have enough resolution for plot level data collection. Limitations and future potential uses are also discussed.

Anaesthesia-Related Haemodynamic Complications in Williams Syndrome Patients: A Review of One Institution's Experience

Williams syndrome is a genetic disorder associated with cardiac pathology, including supravalvular aortic stenosis and coronary artery stenosis. Sudden cardiac death has been reported in the perioperative period and attributed to cardiovascular pathology. In this retrospective audit, case note and anaesthetic records were reviewed for all confirmed Williams syndrome patients who had received an anaesthetic in our institution between July 1974 and November 2009. There were a total of 108 anaesthetics administered in 29 patients. Twelve of the anaesthetics (11.1%) were associated with cardiac complications including cardiac arrest in two cases (1.85%). Of the two cardiac arrests, one patient died within the first 24 hours postanaesthetic and the other patient survived, giving an overall mortality of 0.9% (3.4%). We conclude that Williams syndrome confers a significant anaesthetic risk, which should be recognised and considered by clinicians planning procedures requiring general anaesthesia.

Biomonitoring study of deoxynivalenol exposure and association with typical cereal consumption in Swedish adults

Deoxynivalenol (DON) is a mycotoxin of the trichothecene family commonly found in cereals infested with different Fusarium species. DON acts primarily on the gastrointestinal and immune system and is suspected to be an underlying agent causing several outbreaks of gastrointestinal disorder among humans, which prompts studies of human exposure and estimations of intake among populations. However, assessing human exposure to mycotoxins is associated with several difficulties. Therefore, a study was undertaken among adults (18-80 years) in a subgroup of Riksmaten, the Swedish national survey investigating dietary habits, examining both the association between urinary DON concentration and dietary intake of cereals, and estimations of daily DON intake. The results indicate that exposure to DON is common among Swedish adults, as this mycotoxin was detected in 292 out of 326 urine samples (90%) at levels ranging from non-detectable to 65.8 ng DON/ml urine with a median level of 2.9 ng/ml. Furthermore, urinary DON (ng/mg creatinine) was associated with intake (g/day) of total cereal grain as well as whole grain. Urinary DON was also significantly associated with breakfast cereals and porridge consumption (P<0.05). Estimated DON intake in this study ranged between 2.5 and 5,443 ng/kg body weight (bw). 1% of the individuals had estimated intakes above the group provisional maximum tolerable daily intake (PMTDI; 1 μg/kg), whereas the mean and median intakes of 159 and 84 ng DON/kg bw, respectively, were considerably below the PMTDI. Along with the toxicological profile of DON, no serious health implications are to be expected for the majority of Swedish adults, although a potential health concern remains for some high cereal consumers. In conclusion, biomonitoring could prove to be a valuable tool for observing DON exposure among populations.

Perspectives on the development of antioxidant antiepileptogenic agents

Epilepsy is a chronic disorder of abnormal electrical activity in the brain characterized by recurrent unprovoked seizures. Currently used pharmaceutical agents do not treat the underlying disease process, and a significant proportion of epileptic patients are refractory to current therapies. Therefore there is a strong need for additional therapeutic agents, especially those that address the underlying disease process of epileptogenesis. The redox potential of cells is maintained by an appropriate balance between pro- and anti-oxidative molecules; oxidative stress and increases in toxic reactive oxygen species occur when this balance shifts towards oxidation. Neural tissues are especially sensitive to oxygen levels, and oxidative stress is thought to be involved in epileptogenesis. Increases in reactive oxygen species occur in response to sustained neuronal electrical activity and seizures. Therefore antioxidants have been suggested as therapeutic design strategies for the treatment and modulation of epilepsy. This minireview focuses on several key antioxidants and agents involved in defending against oxidative stress that may be targets for new antiepileptogenic drug design, including directacting antioxidants, Nrf2-activating agents, and prolyl-4-hydroxylase inhibitors. A description of the necessary physicochemical properties and a summary of animal models that are thought to be useful for developing antiepileptogenic agents are presented.

Real-time PCR detection of Fusarium species in Swedish oats and correlation to T-2 and HT-2 toxin content

Contamination of Fusarium moulds and subsequent production of mycotoxins is a common problem in cereals grown in Northern Europe. Oats is the third most important cereal crop in Sweden and is commonly contaminated by Fusarium. To date there are no published reports on the distribution of trichothecene-producing Fusaria in Swedish oats and correlation to T-2 and HT-2, the two most dominant toxins. Identification of Fusarium species by traditional methods requires specific skill and experience and quantification of specific species is not possible. Using modern molecular methods such as real-time PCR both identification and quantification of specific Fusarium species are possible directly from the food or feed samples. In this study, specific methods for Fusarium langsethiae, Fusarium sporotrichioides, Fusarium graminearum, Fusarium culmorum and Fusarium poae as well as for the total amount of DNA from trichothecene-producing species were evaluated with respect to precision, robustness and efficiency and then used in the analysis of oat samples. Sixty-two oat samples were taken from field trial harvests from 2006-2008 in the central and southern parts of Sweden and analysed for the presence of Fusarium species by using species-specific real-time PCR-based methods with TaqMan or SYBR Green biochemistry. The T-2 and HT-2 toxin content was analysed by gas chromatography with electron capture detection of the toxins' pentafluoropropyl derivatives. The results showed that F. langsethiae and F. poae were the most dominant Fusarium species among those tested in Swedish oats during this period. The DNA level of F. langsethiae correlated well with the level of T-2 and HT-2 toxin (r=0.7), indicating that this species was the most important producer of T-2 and HT-2 toxins in Swedish oats during the sampling period (2006 to 2008). It can also be concluded that real-time PCR is a powerful tool when studying Fusarium species distribution in oats.

Imageless computer navigation without pre-operative templating may lead to malpreparation of the femoral head in hip resurfacing

The computed neck-shaft angle and the size of the femoral component were recorded in 100 consecutive hip resurfacings using imageless computer-navigation and compared with the angle measured before operation and with actual component implanted. The reliability of the registration was further analysed using ten cadaver femora. The mean absolute difference between the measured and navigated neck-shaft angle was 16.3° (0° to 52°). Navigation underestimated the measured neck-shaft angle in 38 patients and the correct implant size in 11. Registration of the cadaver femora tended to overestimate the correct implant size and provided a low level of repeatability in computing the neck-shaft angle.

Prudent pre-operative planning is advisable for use in conjunction with imageless navigation since misleading information may be registered intraoperatively, which could lead to inappropriate sizing and positioning of the femoral component in hip resurfacing.

Imageless computer navigation for placement of the femoral component in resurfacing arthroplasty of the hip

We have investigated the accuracy of placement of the femoral component using imageless navigation in 100 consecutive Birmingham Hip Resurfacings. Pre-operative templating determined the native neck-shaft angle and planned stem-shaft angle of the implant. The latter were verified post-operatively using digital anteroposterior unilateral radiographs of the hip. The mean neck-shaft angle determined before operation was 132.7 degrees (118 degrees to 160 degrees ). The mean planned stem-shaft angle was a relative valgus alignment of 9.7 degrees (SD 2.6). The stem-shaft angle after operation differed from that planned by a mean of 2.8 degrees (SD 2.0) and in 86% of cases the final angle measured within +/- 5 degrees of that planned. We had no instances of notching of the neck or varus alignment of the implant in our series. A learning curve was observed in the time taken for navigation, but not for accurate placement of the implant. Navigation in hip resurfacing may afford the surgeon a reliable and accurate method of placement of the femoral component.

Cancellous bone screw purchase: A comparison of synthetic femurs, human femurs, and finite element analysis

Biomechanical assessments of orthopaedic fracture fixation constructs are increasingly using commercially available analogues such as the fourth-generation composite femur (4GCF). The aim of this study was to compare cancellous screw purchase directly between these surrogates and human femurs, which has not been done previously. Synthetic and human femurs each had one orthopaedic cancellous screw (major diameter, 6.5 mm) inserted along the femoral neck axis and into the spongy bone of the femoral head to a depth of 30 mm. Screws were removed to obtain pull-out force, shear stress, and energy values. The three experimental study groups ( n = 6 femurs each) were the 4GCF with a ‘solid’ cancellous matrix, the 4GCF with a ‘cellular’ cancellous matrix, and human femurs. Moreover, a finite element model was developed on the basis of the material properties and anatomical geometry of the two synthetic femurs in order to assess cancellous screw purchase. The results for force, shear stress, and energy respectively were as follows: 4GCF solid femurs, 926.47 ± 66.76 N, 2.84 ± 0.20 MPa, and 0.57 ± 0.04 J; 4GCF cellular femurs, 1409.64 ± 133.36 N, 4.31 ± 0.41 MPa, and 0.99 ± 0.13 J; human femurs, 1523.29 ± 1380.15 N, 4.66 ± 4.22 MPa, and 2.78 ± 3.61 J. No statistical differences were noted when comparing the three experimental groups for pull-out force ( p = 0.413), shear stress ( p = 0.412), or energy ( p = 0.185). The 4GCF with either a ‘solid’ or ‘cellular’ cancellous matrix is a good biomechanical analogue to the human femur at the screw thread—bone interface. This is the first study to perform a three-way investigation of cancellous screw purchase using 4GCFs, human femurs, and finite element analysis.

Femoral neck fracture following hip resurfacing

A total of 20 pairs of fresh-frozen cadaver femurs were assigned to four alignment groups consisting of relative varus (10° and 20°) and relative valgus (10° and 20°), 75 composite femurs of two neck geometries were also used. In both the cadaver and the composite femurs, placing the component in 20° of valgus resulted in a significant increase in load to failure. Placing the component in 10° of valgus had no appreciable effect on increasing the load to failure except in the composite femurs with varus native femoral necks. Specimens in 10° of varus were significantly weaker than the neutrally-aligned specimens.

The results suggest that retention of the intact proximal femoral strength occurs at an implant angulation of ≥ 142°. However, the benefit of extreme valgus alignment may be outweighed in clinical practice by the risk of superior femoral neck notching, which was avoided in this study.

A biomechanical assessment of the coupling of torsion and tension in the human scapholunate ligament

The mechanical behaviour of human scapholunate ligaments is not well described in the literature with regard to torsion. In this study, intact scapholunate specimens were mechanically tested in torsion to determine whether a simultaneous tensile load was generated. Human intact scapholunate specimens ( n = 19) were harvested. The scaphoid and lunate bones were potted in square chambers using epoxy cement, while the interposing ligament remained exposed. Each specimen was mounted rigidly in a specially designed test jig and remained at a fixed axial length during all tests. Specimens were subjected to a torsional load regime that included cyclic preconditioning, ramp-up, stress relaxation, ramp-down, rest, and torsion to failure. Torque and axial tension were monitored simultaneously. The relationship between torsion and tension was determined. Graphs of torque versus tension were generated, from which outcome measures were extracted. Tests demonstrated a clear relationship between applied torsion and the resulting generation of tension for the ligament during ramp-up (torsion-to-tension ratio, 38.86 ± 29.00 mm; linearity coefficient R2 = 0.89 ± 0.15; n = 19), stress relaxation (torsion-to-tension ratio, 23.43 ± 15.84 mm; R2 = 0.90 ± 0.09; n = 16), and failure tests (torsion-to-tension ratio, 38.81 ± 26.39 mm; R2 = 0.77 ± 0.20; n = 16). No statistically significant differences were detected between the torsion-to-tension ratios ( p = 0.13) or between the linearity ( R2) of the best-fit lines ( p > 0.085). A strongly coupled linear relationship between torsion and tension for the scapholunate ligament was exhibited in all test phases. This may suggest interplay between these two parameters in the stabilization of the ligament during normal motion and for injury cascades.