The global burden of occupationally related low back pain: estimates from the Global Burden of Disease 2010 study

OBJECTIVES

The study was part of the Global Burden of Disease 2010 study and aimed to quantify the burden arising from low back pain (LBP) due to occupational exposure to ergonomic risk factors.

METHODS

Exposure prevalence was based on occupation distribution; estimates of relative risk came from a meta-analysis of relevant published literature. The work-related burden was estimated as disability-adjusted life years (DALYs). Estimates were made for each of 21 world regions and 187 countries, separately for 1990 and 2010 using consistent methods.

RESULTS

Worldwide, LBP arising from ergonomic exposures at work was estimated to cause 21.7 million DALYs in 2010. The overall population attributable fraction was 26%, varying considerably with age, sex and region. 62% of LBP DALYs were in males-the largest numbers were in persons aged 35-55 years. The highest relative risk (3.7) was in the agricultural sector. The largest number of DALYs occurred in East Asia and South Asia, but on a per capita basis the biggest burden was in Oceania. There was a 22% increase in overall LBP DALYs arising from occupational exposures between 1990 and 2010 due to population growth; rates dropped by 14% over the same period.

CONCLUSIONS

LBP arising from ergonomic exposures at work is an important cause of disability. There is a need for improved information on exposure distributions and relative risks, particularly in developing countries.

Orientation Development of Mixed Anisotropic Particles in Compounds

An experimental study of the development of orientation of mixed fiber and flake polymer compounds in polymer processing operation including extrusion and molding is discussed. Aramid fiber and talc and mica flakes are studied. The orientation of the particles is determined using wide angle x-ray diffraction. It is found that mixed particle systems lead to lower orientation of both fibers and flakes. The fibers tend to orient in the primary machine direction, while the flakes tend to orient perpendicular to the fibers. This is distinct from fiber compounds and flake compounds where fibers orient in the plane of the machine and transverse directions and flakes orient parallel to machine surfaces.

Development of Phase Morphology of a Polyethylene-Polyamide 6-Blend in a Modular Co-rotating Twin Screw Extruder

A basic study of blending two different polymers (polyethylene and polyamide 6) in a modular co-rotating twin screw extruder is presented. The development of phase morphology was observed along the axis of the modular screw. Five different modular screw designs are considered. We first look at a machine containing all right-handed screw elements. We then consider a machine with all right-handed elements plus a single left-handed screw element. The study then turns to machines with combined screw and kneading disc elements. The kneading discs play a key role in both melting polymers and in enhancing dispersive mixing. Increasing the number of kneading disc blocks gives enhanced dispersion.

Flow Mechanisms, Material Distributions and Phase Morphology Development in a Modular Intermeshing Counter-Rotating Twin Screw Extruder of Leistritz Design

An experimental study is presented of the mixing of polyamide-6 and polyethylene in a Leistritz modular counter-rotating twin screw extruder. Seven different screw configurations were investigated and the material distributions and phase morphology developments along the axis of the screw were characterized. The behavior of different modular elements was determined including screw flights of varying thickness, Kiesskalt compression elements and shearing elements.

Differentiating xanthogranulomatous cholecystitis from wall-thickening type of gallbladder cancer: added value of diffusion-weighted MRI

AIM

To evaluate the benefit of diffusion-weighted imaging (DWI) in differentiating xanthogranulomatous cholecystitis from the wall-thickening type of gallbladder cancer.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board. Fourteen patients with xanthogranulomatous cholecystitis and 19 patients with the wall-thickening type of gallbladder cancer were included. Qualitative (visual diffusion restriction compared to liver parenchyma) and quantitative [apparent diffusion coefficient (ADC)] analyses were performed. Conventional MRI findings including dynamic enhancement pattern between the two groups were also analysed. Two observers independently reviewed conventional magnetic resonance imaging (MRI) images and subsequently reviewed combined conventional MRI and DWI images. Pairwise comparison of the receiver operating characteristic (ROC) curves was used to compare diagnostic performances.

RESULTS

In conventional MRI findings, xanthogranulomatous cholecystitis showed significant continuity of enhancing mucosal line [79% (11/14) versus 26% (5/19), p = 0.003] and intramural T2-high signal intensity [64% (9/14) versus 21% (4/19), p = 0.012] compared to the wall-thickening type of gallbladder cancer. The enhancement pattern of gallbladder cancer compared to liver parenchyma showed earlier onset than that of xanthogranulomatous cholecystitis (p = 0.001). Diffusion restriction was more frequently seen in the wall-thickening type of gallbladder cancer (68%, 13/19) than in xanthogranulomatous cholecystitis (7%, 1/14; p < 0.001). The mean ADC value of xanthogranulomatous cholecystitis was higher than that of the wall-thickening type of gallbladder cancer with statistical significance (1.637 × 10(-3) mm(2)/s versus 1.076 × 10(-3) mm(2)/s, p = 0.005). Diagnostic performance [area under ROC curve (Az)] of both observers improved significantly after additional review of DWI; Az improved from 0.737 to 0.930 (p = 0.027) for observer 1 and from 0.675 to 0.938 (p = 0.008) for observer 2.

CONCLUSION

Addition of DWI to conventional MRI improves discrimination between xanthogranulomatous cholecystitis and the wall-thickening type of gallbladder cancer.

Gonadotrophin-releasing hormone signalling downstream of calmodulin

Gonadotrophin-releasing hormone (GnRH) regulates reproduction via binding a G-protein coupled receptor on the surface of the gonadotroph, through which it transmits signals, mostly via the mitogen-activated protein (MAPK) cascade, to increase synthesis of the gonadotrophin hormones: luteinising hormone (LH) and follicle-stimulating hormone (FSH). Activation of the MAPK cascade requires an elevation in cytosolic Ca(2+) levels, which is a result of both calcium influx and mobilisation from intracellular stores. However, Ca(2+) also transmits signals via an MAPK-independent pathway, through binding calmodulin (CaM), which is then able to bind a number of proteins to impart diverse downstream effects. Although the ability of GnRH to activate CaM was recognised over 20 years ago, only recently have some of the downstream effects been elucidated. GnRH was shown to activate the CaM-dependent phosphatase, calcineurin, which targets gonadotrophin gene expression both directly and indirectly via transcription factors such as nuclear factor of activated T-cells and Nur77, the Transducer of Regulated CREB (TORC) co-activators and also the prolyl isomerase, Pin1. Gonadotrophin gene expression is also regulated by GnRH-induced CaM-dependent kinases (CaMKs); CaMKI is able to derepress the histone deacetylase-inhibition of β-subunit gene expression, whereas CaMKII appears to be essential for the GnRH-activation of all three subunit genes. Asides from activating gonadotrophin gene expression, GnRH also exerts additional effects on gonadotroph function, some of which clearly occur via CaM, including the proliferation of immature gonadotrophs, which is dependent on calcineurin. In this review, we summarise these pathways, and discuss the additional functions that have been proposed for CaM with respect to modifying GnRH-induced signalling pathways via the regulation of the small GTP-binding protein, Gem, and/or the regulator of G-protein signalling protein 2.