Diurnal variation of anterior scleral and conjunctival thickness

Purpose To examine whether anterior scleral and conjunctival thickness undergoes significant diurnal variation over a 24-hour period. Methods Nineteen healthy young adults (mean age 22 ± 2 years) with minimal refractive error (mean spherical equivalent refraction -0.08 ± 0.39 D), had measures of anterior scleral and conjunctival thickness collected using anterior segment optical coherence tomography (AS-OCT) at seven measurement sessions over a 24-hour period. The thickness of the temporal anterior sclera and conjunctiva were determined at 6 locations (each separated by 0.5 mm) at varying distances from the scleral spur for each subject at each measurement session. Results Both the anterior sclera and conjunctiva were found to undergo significant diurnal variations in thickness over a 24-hour period (both p <0.01). The sclera and conjunctiva exhibited a similar pattern of diurnal change, with a small magnitude thinning observed close to midday, and a larger magnitude thickening observed in the early morning immediately after waking. The amplitude of diurnal thickness change was larger in the conjunctiva (mean amplitude 69 ± 29 μm) compared to the sclera (21 ± 8 μm). The conjunctiva exhibited its smallest magnitude of change at the scleral spur location (mean amplitude 56 ± 17 μm) whereas the sclera exhibited its largest magnitude of change at this location (52 ± 21 μm). Conclusions This study provides the first evidence of diurnal variations occurring in the thickness of the anterior sclera and conjunctiva. Studies requiring precise measures of these anatomical layers should therefore take time of day into consideration. The majority of the observed changes occurred in the early morning immediately after waking and were of larger magnitude in the conjunctiva compared to the sclera. Thickness changes at other times of the day were of smaller magnitude and generally not statistically significant.

HR-MAS NMR spectroscopy shows regional metabolite variation in bovine articular cartilage

Mechanical stress is an important external factor effecting the development and maintenance of articular cartilage. The metabolite profile of diseased cartilage has been well studied but there is limited information about the variation in metabolite profile of healthy cartilage. With the importance of load in maintaining healthy cartilage, regional differences in metabolite profile associated with differences in load may provide information on how load contributes to the maintenance of healthy cartilage. HR-MAS NMR spectroscopy allows the assessment of tissue samples without modification and was used for assessing the difference in metabolic profile between the load bearing and non-load bearing regions of the bovine articular cartilage. In this preliminary study, we examined cartilage from tibia and femur of four knee joints. Sixteen pairs of 1D-NOESY spectra were acquired. Principle component analysis (PCA) identified chemical shifts responsible for variance. SBASE (AMIX) and the Human Metabolome Database were used in conjunction with previous reported cartilage data for identifying metabolites associated with the PCA results. The major contributors to load-related differences in metabolite profile were N-acetyl groups, lactate and phosphocholine peaks. Integrals of these regions were further analysed using a Student's t-test. In load bearing cartilage regions. N-acetyl groups and phosphocholine were found at significantly higher concentration (p < 0.05 and p < 0.005, respectively) in both femur and tibia, while lactate was reduced in load bearing cartilage (p < 0.005). The results of this pilot HR-MAS NMR study demonstrate its ability to provide useful metabolite information for healthy cartilage.

Natural variation and Biogeography of the melon fruit fly, Zeugodacus cucurbitae (Diptera : Tephritidae), in Southeast-Asia and the west-pacific

This thesis used multidisciplinary approaches which greatly enhance our understanding of population structure and can be particularly powerful tools for resolving variation of melon fly over geographic and temporal scales, and for determining invasive pathways. The results from this thesis reinforce the value of integrating multiple data sets to better understand and resolve natural variation within an important pest to determine whether there are cryptic species, discrete lineages or host races, and to identify dispersal pathways in an invasive pest. These results are instructive for regional biosecurity, trade and quarantine, and provide important background for future area-wide management programmes. The integrative methodology adopted in this thesis is applicable to a variety of other insect pests.

Regional variation in social isolation amongst older Australians

Regional studies globally have a strong focus on understanding the causes of variation in the economic performance and wellbeing of regions and this emphasis acknowledges that the strength of the local or regional economy plays a determinant role in shaping quality of life. Regional research has been less active in considering spatial variation in other factors that are critical to individual and societal wellbeing. For example, the regional studies community has been absent from the debate on the social determinants of health and how these influences vary spatially. This paper considers the results of a cross sectional survey of Australians aged 65 and over that focussed on social connections and wellbeing. It examines regional variations in the incidence of social isolation within the older population. It finds that while the incidence of self-reported social isolation amongst older persons is broadly consistent with earlier studies, it demonstrates a spatial patterning that is unexpected. The paper considers community-building activities in addressing the impacts of social isolation, including the role of urban design, and suggests that there is a need to supplement the national overview presented there through more detailed studies focussed on individual localities.

Chromosomal rearrangements, phenotypic variation and modularity: A case study from a contact zone between house mouse Robertsonian races in Central Italy

The Western European house mouse, Mus musculus domesticus, is well-known for the high frequency of Robertsonian fusions that have rapidly produced more than 50 karyotipic races, making it an ideal model for studying the mechanisms of chromosomal speciation. The mouse mandible is one of the traits studied most intensively to investigate the effect of Robertsonian fusions on phenotypic variation within and between populations. This complex bone structure has also been widely used to study the level of integration between different morphogenetic units. Here, with the aim of testing the effect of different karyotypic assets on the morphology of the mouse mandible and on its level of modularity, we performed morphometric analyses of mice from a contact area between two highly metacentric races in Central Italy. We found no difference in size, while the mandible shape was found to be different between the two Robertsonian races, even after accounting for the genetic relationships among individuals and geographic proximity. Our results support the existence of two modules that indicate a certain degree of evolutionary independence, but no difference in the strength of modularity between chromosomal races. Moreover, the ascending ramus showed more pronounced interpopulation/race phenotypic differences than the alveolar region, an effect that could be associated to their different polygenic architecture. This study suggests that chromosomal rearrangements play a role in the house mouse phenotypic divergence, and that the two modules of the mouse mandible are differentially affected by environmental factors and genetic makeup.