Antifouling potential of lubricious, micro-engineered, PDMS elastomers against zoospores of the green fouling alga Ulva (Enteromorpha)

The settlement and release of Ulva spores from chemically modified, micro-engineered surface topographies have been investigated using poly(dimethyl siloxane) elastomers (PDMSe) with varying additions of non-network forming poly(dimethyl siloxane) based oils. The topographic features were based on 5 microns wide pillars or ridges separated by 5, 10, or 20 microns wide channels. Pattern depths were 5 or 1.5 microns. Swimming spores showed no marked difference in settlement on smooth surfaces covered with excess PDMS oils. However, incorporation of oils significantly reduced settlement density on many of the surfaces with topographic features, in particular, the 5 microns wide and deep channels. Previous results, confirmed here, demonstrate preferences by the spores to settle in channels and against pillars with spatial dimensions of 5 microns, 10 microns and 20 microns. The combination of lubricity and pillars significantly reduced the number of attached spores compared to the control, smooth, unmodified PDMSe surfaces when exposed to turbulent flow in a flow channel. The results are discussed in relation to the energy needs for spores to adhere to various surface features and the concepts of ultrahydrophobic surfaces. A factorial, multi-level experimental design was analyzed and a 2nd order polynomial model was regressed for statistically significant effects and interactions to determine the magnitude and direction of influence on the spore density measurements between factor levels.     

The PE multigene family: a 'molecular mantra' for mycobacteria

The PE multigene family of Mycobacterium tuberculosis is remarkable in that it is composed of approximately 100 highly homologous genes that are found only in mycobacteria. Early evidence suggests that proteins encoded by certain members of this gene family could be present in the mycobacterial cell wall, impact antigen-presentation pathways and the ensuing host immune responses, and also provide a mechanism for generating antigenic diversity in mycobacteria.     

Growth and growth hormone status after a bone marrow transplant

The three most common clinical situations which have given rise to diagnostic and therapeutic issues involve the child treated for: (1) a brain tumour or extracranial tumour with radiotherapy (XRT) which includes an XRT dose of > or =30 Gy to the hypothalamic-pituitary axis; (2) acute lymphoblastic leukaemia with a cranial XRT dose of 18-24 Gy, and (3) haematological malignancy or solid tumour requiring total body irradiation (dose 10-14 Gy) and BMT. The decision about the intent to treat and the timing of GH replacement needs to be taken in collaboration with the paediatric oncologist who will provide guidance about overall prognosis and the risk of relapse. After a dose of > or =30 Gy to the hypothalamic pituitary axis the risk of GH deficiency (GHD) 2 years later is very high (>50%) and therefore there is 'solid' epidemiological evidence, which predicts outcome. Therapeutically the choice is whether or not to offer GH replacement at 2 years in the presence of biochemical evidence of GHD but independent of auxology, or wait until the growth rate declines. Diagnostically the IGF-1 SDS is more useful than previously thought, particularly if XRT-induced GHD is severe; there may, however, be systematic discordancy between the GH responses to different pharmacological stimuli (ITT vs. arginine). For irradiated children in categories 2 and 3, greater emphasis is placed on auxology in determining the need for assessment of GH status. Early rather than very precocious puberty is a real issue and needs to be actively treated with a GnRH analogue if final height appears to be significantly compromised.     

Prevention and correction of temporal hair loss in rhytidectomy

Routine incisions in the temporal area for rhytidectomy often remove hair-bearing skin anterior to the ear. This results in a cosmetic deformity, making the surgical intervention clearly visible. This is especially problematic for revision rhytidectomy or for patients with naturally high hairlines. This article describes a systematic approach to the temporal hairline and introduces a novel, hair-bearing, transposition flap that corrects iatrogenic loss of the preauricular tuft of hair.     

Determination of an Optimal Pitfall Trap Size for Sampling Spiders in a Western Australian Jarrah Forest

Pitfall trapping is a sampling technique extensively used to sample surface foraging invertebrates for biological diversity studies and ecological monitoring. To date, very few invertebrate studies have considered what trap size is optimal for sampling spiders. This study presents preliminary findings from a single short sampling period on the role of trap size in sampling spiders in a Western Australian Jarrah forest. Four different trap diameters (4.3, 7.0, 11.1 and 17.4 cm) were examined (4 trap sizes × 15 replicates = 60 traps). Two-way ANOVAs revealed no significant interaction effects between trap size or the spatial positioning of transects within the study site along which the pitfall traps were arranged. Post-hoc tests revealed abundance, family richness and species richness increased with increasing trap sizes for traps 7.0 cm. No significant differences in these dependent variables occurred between 4.3 and 7.0 cm traps, or for species richness between 11.1 and 17.4 cm traps. Determination of an optimal trap size was undertaken by bootstrapping and calculating species accumulation curves for increasing numbers of traps used. Three different criteria were considered: equivalent number of traps (15), standardized sampling intensity (cumulative trap circumference, approximately 207 cm) and standardized cumulative handling time (approximately 1 hour 17 minutes). The largest trap size (17.4 cm) was most efficient in terms of number of traps and trap circumference. For the same number of traps, it caught 19 species whereas all other trap sizes caught ten species. At the standardized circumference, it caught seven species whereas all other trap sizes caught five. For handling time, however, the two largest trap sizes (17.4 and 11.1 cm) were optimal. Both caught nine species whereas all other traps caught 相似文献   

Studies on the ultrastructure and histochemistry of the lymph system of Gastrodiscoides hominis (Paramphistoma: Digenea).

The lymphatic system of the paramphistome, Gastrodiscoides hominis consists of numerous fluid-filled branches embedded in parenchyma and surrounded by extracellular material and is closely associated with the major organ systems of the fluke. The lymph matrix consists of a cytoplasmic syncytium within which nuclei, mitochondria and various sized granules and membranous structures occur. The granules found throughout the lymph system morphologically resemble autophagosomes and lysosomes. The lymph system provides a storage site for proteins which can be broken down to amino acids via autophagy, for subsequent mobilization and transport to tissues undergoing active protein synthesis. Many branches of the lymph system are surrounded by specialized parenchymal cells referred to as juxta-lymphatic cells. These cells are apparently associated with autophagic degradation of sequestered lymph cytoplasm, which may serve as an additional mechanism for the mobilization and transport of precursor molecules throughout the fluke via the parenchymal network.     

Copper-induced structural changes in the ovine prion protein are influenced by a polymorphism at codon 112

Prion diseases are associated with conformational change in the copper-binding protein PrP. The copper-binding sites in PrP are located in the N-terminal region of the molecule and comprise a series of tandem repeats of the sequence PHGGGWGQ together with two histidines at residues 96 and 111 (human PrP numbering). The co-ordination of copper ions within the non-octapeptide repeat metal ion-binding site involves Met109 (human numbering, which corresponds with Met112 in ovine PrP) and the binding of copper to this site leads to an increase in beta-sheet formation in PrP. Here we have investigated the influence of the M112T polymorphism on copper-induced structural changes in ovine recombinant PrP. M112ARQ and T112ARQ ovine PrP show similar secondary structure although M112ARQ appears more thermostable than T112ARQ. Following treatment with copper, M112ARQ showed a greater increase in beta-sheet content than did T112ARQ when measured by CD spectroscopy and by ELISA using anti-PrP monoclonal antibodies. These biochemical and biophysical differences between M112ARQ and T112ARQ correlate with similar differences seen between allelic variants of ovine PrP associated with susceptibility and resistance to classical scrapie. These observations suggest that T112ARQ may provide a measure of resistance to classical scrapie pathogenesis compared to M112ARQ.     

The effects of estrogen deficiency and bisphosphonate treatment on tissue mineralisation and stiffness in an ovine model of osteoporosis

While much research has been dedicated to understanding osteoporosis, the nature of mineral distribution and the mechanical property variation in diseased bone is poorly understood. The current study aimed to determine the effect of estrogen deficiency and bisphosphonate therapy on bone tissue properties using an ovine model of osteoporosis. Skeletally mature animals (4+ years) were divided into an ovariectomy group (ovx, n=20) and a non treatment control group (control, n=20). A zoledronic acid treated group was also included in which animals were estrogen deficient for 20 months prior to receiving treatment (Zol, n=4). Half of the control and ovx groups were euthanized 12 or 31 months post-operatively and all Zol animals were euthanised at 31 months. Individual trabeculae were removed from the proximal femur and were analysed at specific locations across the width of the trabeculae. The mineral content was measured using quantitative backscatter electron imaging and the modulus was measured using nanoindentation. The spatial distribution of tissue modulus and mineral content in bone from ovariectomised animals was similar to control. However, ovariectomy significantly reduced the overall mineral content and tissue modulus relative to the control group after 12 months. Interestingly, significant differences were not maintained 31 months post-OVX. Treatment with zoledronic acid increased the mineral content and tissue modulus relative to both the ovariectomised and control groups. Zoledronic acid was also found to alter the mineral and modulus gradients normally associated with healthy bone tissue. The current study provides evidence that both estrogen deficiency and zoledronic acid therapy significantly alter mineral content and the mechanical properties of trabecular tissue.     

200 injuries caused by playground equipment.

Two-hundred children with injuries caused by playground equipment were studied. Whereas only about 9% of the total casualty attendances are for fractures, 26-5% (53) of these children had fractures. The climbing frame and the slide seemed to be associated with more severe injuries than the swing or other equipment, but more cases need to be studied to confirm this. The youngest children were at particular risk on equipment such as the wooden rocking horse or roundabout, when the speed of operation could be controlled by older children. Many of the injuries to the very youngest children occurred when they were walking behind a moving swing. Faulty equipment did not seem to be a major factor in causing accidents, but the use by older children of apparatus designed for young ones led to accidents. There was supervision, either at home, in a school playground, or in a park, in 62% of the cases. Many of the accidents were the result of the normal desire of children for experimentation and adventure.