Developmental physiology of the red swamp crayfish Procambarus clarkii

The primary goal of this research was to gain an understanding of the temporal sequence of cardiac regulatory mechanisms throughout the development of the red swamp crayfish Procambarus clarkii. Investigations focused on cardiac development and the ontogeny of the regulatory mechanisms of the cardiovascular system. Investigations concentrated on two areas: (1) the development of a staging scheme for P. clarkii, and (2) the ontogeny of neurohormonal regulation of the heart of P. clarkii. An embryonic staging scheme was established to allow a comparison between animals of the same chronological-age (fertilized at the same time), but not of the same developmental stage (morphological and physiological features compared). The staging scheme was established using embryos, noting only gross morphological and physiological landmarks that minimized trauma and invasion into the animal. Cardiovascular parameters (heart rate, stroke volume, and cardiac output) were determined throughout development by using a videomicroscopy technique and dimensional analysis. Heart rate, stroke volume, and cardiac output measured throughout development of the crayfish decreased significantly in late stage embryos, just prior to hatching. This decrease was thought to be due to an internal hypoxia experienced by the late stage embryo. When late stage embryos were exposed to hyperoxic water, heart rate increased significantly, suggesting that the decrease in cardiovascular parameters just prior to hatching is due to an internal hypoxia. To determine the stage at which components of the regulatory system come on-line, the temporal sequence of cardiac neurohormonal regulation was established by infusion of cardioactive drugs into the pericardial sinus of embryonic crayfish at defined developmental stages. (Abstract shortened by UMI.)

Gross motor and gait abilities of children with Hurler syndrome, pre and post umbilical cord blood transplant

Children with Hurler syndrome have significant impairments to body structure and function that result from glycosaminoglycans accumulating in cells throughout the body. Little is known about activity limitations or more specifically gross motor and gait abilities in this population. The advent of new treatments such as umbilical cord blood transplantation (UCBT) is increasing the lifespan of children with Hurler syndrome. Information on gross motor and gait abilities with and without medical interventions such as UCBT will enable the medical community, therapists, and families to help children with Hurler syndrome maximize their motor abilities. The purpose of this dissertation was to describe the gross motor and gait abilities of children with Hurler syndrome pre and post UCBT. The first study presents a case series of 4 children who had not received medical intervention to alter their enzyme levels. The second study describes changes in gross motor abilities over time for 21 children who received UCBT. The third study describes changes in selected gait parameters of 18 children with Hurler syndrome post UCBT. The combined results of these studies indicate that children with Hurler syndrome have below average gross motor abilities and significant joint range of motion impairments by 10 months of age. Gross motor abilities are most delayed in the area of locomotion prior to and after UCBT. Following UCBT, children with Hurler syndrome gain locomotor and object manipulation abilities at the same iii or a faster rate than typically developing children. However, they gain stationary balance abilities at a rate slower than their peers. In addition, children with Hurler syndrome post UBCT walk with age appropriate velocity and step length by 48 months of age, after having immature gait at 24 and 36 months of age. The findings from this dissertation suggest that children with Hurler syndrome do have the ability to gain new gross motor abilities and improve gait velocity and step length with increasing time post-UCBT. However, significant discrepancies in the children's abilities on various gross motor domains maybe related to orthopedic conditions, strength, and balance deficits. There findings warrant further investigation

Do graduate entry nursing student’s experience ‘Imposter Phenomenon’?: an issue for debate

The recruitment of Graduates into the nursing profession is seen as advantageous in the academic literature. Conversely educated nurses are often portrayed in the media as “too posh to wash”. We would argue these conflicting discourses have a negative effect on graduate entry nurse education. Graduate nursing students may be particularly susceptible to “Imposter Phenomenon” a concept that describes an "internal experience of intellectual phoniness" exhibited by individuals who appear successful to others, but internally feel incompetent. We would like to encourage debate through the presentation of a small set of pilot data that established that 74% of the participants had frequent to intense experiences of Imposter Phenomenon. Students experienced feelings of failure despite consistent high achievement. Our findings and the prevalent negative rhetoric surrounding highly educated student nurses raise concerns regarding the impact of the anti-intellectualism on the Graduate entry student’s perception of self. Others may argue that this could simply be a 'natural' or expected level of anxiety in a time of transition that has no lasting impact. We debate this issue in relation to the existing literature to encourage critical dialogue

Long-Term Stability of Horseshoe Orbits

Unlike Trojans, horseshoe coorbitals are not generally considered to be long-term stable (Dermott and Murray, 1981; Murray and Dermott, 1999). As the lifetime of Earth's and Venus's horseshoe coorbitals is expected to be about a Gyr, we investigated the possible contribution of late-escaping inner planet coorbitals to the lunar Late Heavy Bombardment. Contrary to analytical estimates, we do not find many horseshoe objects escaping after first 100 Myr. In order to understand this behaviour, we ran a second set of simulations featuring idealized planets on circular orbits with a range of masses. We find that horseshoe coorbitals are generally long lived (and potentially stable) for systems with primary-to-secondary mass ratios larger than about 1200. This is consistent with results of Laughlin and Chambers (2002) for equal-mass pairs or coorbital planets and the instability of Jupiter's horseshoe companions (Stacey and Connors, 2008). Horseshoe orbits at smaller mass ratios are unstable because they must approach within 5 Hill radii of the secondary. In contrast, tadpole orbits are more robust and can remain stable even when approaching within 4 Hill radii of the secondary.Comment: Accepted for MNRA

Elucidating the genetic basis of antioxidant status in lettuce (Lactuca sativa).

A diet rich in phytonutrients from fruit and vegetables has been acknowledged to afford protection against a range of human diseases, but many of the most popular vegetables are low in phytonutrients. Wild relatives of crops may contain allelic variation for genes determining the concentrations of these beneficial phytonutrients, and therefore understanding the genetic basis of this variation is important for breeding efforts to enhance nutritional quality. In this study, lettuce recombinant inbred lines, generated from a cross between wild and cultivated lettuce (Lactuca serriola and Lactuca sativa, respectively), were analysed for antioxidant (AO) potential and important phytonutrients including carotenoids, chlorophyll and phenolic compounds. When grown in two environments, 96 quantitative trait loci (QTL) were identified for these nutritional traits: 4 for AO potential, 2 for carotenoid content, 3 for total chlorophyll content and 87 for individual phenolic compounds (two per compound on average). Most often, the L. serriola alleles conferred an increase in total AOs and metabolites. Candidate genes underlying these QTL were identified by BLASTn searches; in several cases, these had functions suggesting involvement in phytonutrient biosynthetic pathways. Analysis of a QTL on linkage group 3, which accounted for >30% of the variation in AO potential, revealed several candidate genes encoding multiple MYB transcription factors which regulate flavonoid biosynthesis and flavanone 3-hydroxylase, an enzyme involved in the biosynthesis of the flavonoids quercetin and kaempferol, which are known to have powerful AO activity. Follow-up quantitative RT-PCR of these candidates revealed that 5 out of 10 genes investigated were significantly differentially expressed between the wild and cultivated parents, providing further evidence of their potential involvement in determining the contrasting phenotypes. These results offer exciting opportunities to improve the nutritional content and health benefits of lettuce through marker-assisted breeding

The Modeled Lifetime Cost-Effectiveness of Published Adherence-Improving Interventions for Antihypertensive and Lipid-Lowering Medications

AbstractObjectiveWe sought to compare the cost-effectiveness of different interventions that have been shown to improve adherence with antihypertensive and lipid-lowering therapy, by combining a burden of nonadherence model framework with literature-based data on adherence-improving interventions.MethodsMEDLINE was reviewed for studies that evaluated ≥1 adherence intervention compared with a control, used an adherence measure other than self-report, and followed patients for ≥6 months. Effectiveness was assessed as Relative Improvement, ratio of adherence with an intervention versus control. Costs, standardized to 12 months and adjusted to 2007 US$, and effectiveness estimates for each intervention were entered into a previously published model designed to measure the burden of nonadherence with antihypertensive and lipid-lowering medications, in a hypertensive population. Outputs included direct medical costs and incremental costs per quality-adjusted life-year (QALY) gained.ResultsAfter screening, 23 eligible adherence-improving interventions were identified from 18 studies. Relative Improvement ranged from 1.13 to 3.60. After eliminating more costly/less effective interventions, two remained. Self-monitoring, reminders, and educational materials incurred total health-care costs of$17,520, and compared with no adherence intervention, had an incremental cost-effectiveness ratio (ICER) of $4984 per QALY gained. Pharmacist/nurse management incurred total health-care costs of$17,896, and versus self-monitoring, reminders, and education had an ICER of $6358 per QALY gained.ConclusionsOf published interventions shown to improve adherence, reminders and educational materials, and a pharmacist/nurse management program, appear to be cost-effective and should be considered before other interventions. Understanding relative cost-effectiveness of adherence interventions may guide design and implementation of efficient adherence-improving program

The Spectral Energy Distributions and Infrared Luminosities of z \approx 2 Dust Obscured Galaxies from Herschel and Spitzer

Dust-obscured galaxies (DOGs) are a subset of high-redshift (z \approx 2) optically-faint ultra-luminous infrared galaxies (ULIRGs, e.g. L_{IR} > 10^{12} Lsun). We present new far-infrared photometry, at 250, 350, and 500 um (observed-frame), from the Herschel Space Telescope for a large sample of 113 DOGs with spectroscopically measured redshifts. Approximately 60% of the sample are detected in the far-IR, confirming their high IR luminosities, which range from 10^{11.6} Lsun < L_{IR} (8-1000 um) <10^{13.6} Lsun. 90% of the Herschel detected DOGs in this sample are ULIRGs and 30% have L_{IR} > 10^{13} Lsun. The rest-frame near-IR (1 - 3 um) SEDs of the Herschel detected DOGs are predictors of their SEDs at longer wavelengths. DOGs with "power-law" SEDs in the rest-frame near-IR show observed-frame 250/24 um flux density ratios similar to the QSO-like local ULIRG, Mrk 231. DOGs with a stellar "bump" in their rest-frame near-IR show observed-frame 250/24 um flux density ratios similar to local star-bursting ULIRGs like NGC 6240. For the Herschel detected DOGs, accurate estimates (within \approx 25%) of total IR luminosity can be predicted from their rest-frame mid-IR data alone (e.g. from Spitzer observed-frame 24 um luminosities). Herschel detected DOGs tend to have a high ratio of infrared luminosity to rest-frame 8 um luminosity (the IR8= L_{IR}(8-1000 um)/v L_{v}(8 um) parameter of Elbaz et al. 2011). Instead of lying on the z=1-2 "infrared main-sequence" of star forming galaxies (like typical LIRGs and ULIRGs at those epochs) the DOGs, especially large fractions of the bump sources, tend to lie in the starburst sequence. While, Herschel detected DOGs are similar to scaled up versions of local ULIRGs in terms of 250/24 um flux density ratio, and IR8, they tend to have cooler far-IR dust temperatures (20-40 K for DOGs vs. 40-50 K for local ULIRGs). Abridged.Comment: 24 pages, 14 figures, 3 tables, accepted for publication in the Astronomical Journa

The production of Necator americanus larvae for use in experimental human infection

Background: Although there is unprecedented interest in experimental human hookworm infection, details of hookworm manufacture and characterisation have been sparsely reported. In this report, we detail the production and characterisation of Necator americanus larvae for use in a recently published clinical trial. Methods: Faeces was obtained from an experimentally infected donor. Faecal hookworm DNA was determined by quantitative PCR. Paired samples were incubated in either sterile water or sterile water mixed with antimicrobials (amphotericin and gentamicin). Coproculture was performed by modified Harada-Mori method. The harvested larvae were then processed in either sterile water or antiseptic solution. Larval yield was then calculated (larvae per gram), larval viability was determined by thermally induced motility assay and microbial burden was determined at the day of harvest, at 48 h and at 7 days. Results: Twenty-eight faecal cultures were performed over 16 months. The faecal hookworm DNA content was variable over this time. There was no association of larval yield with faecal hookworm DNA content. Pre-treatment of faeces with antimicrobials did not influence larval yield. Larval motility was 85.3% (95% CI 79.3–91.3%). Incubation of larvae in antiseptics did not reduce viability at 14 days with a marginal mean of 68.6% (95% CI 59.1–78.1%) washed in water vs. 63.3% (95% CI 53.8 – 72.9%) when incubated in betadine (p = 0.38). Larvae washed in sterile water did not meet microbial bioburden criteria. Incubation in antiseptic resulted in acceptable microbial bioburden at 48 h but not at 7 days. Although the addition of gentamicin did reduce the microbial bio-burden acceptable levels, it was found to significantly lower larval motility at 7 days compared to incubation in sterile water and motility at 7 days 37.8% (95% CI 4.7–70.9%) vs. 67.3% (95% CI 35.2–99.3%, p < 0.001), respectively. Conclusions: Despite standardised culture methodologies and the use of a single donor, larval yield varied considerably between batches and had no association with faecal hookworm DNA. Larval viability decreases over time and the age of larvae at time of use are likely to be important. Microbial bioburden maybe temporarily reduced by incubation in antiseptics and has little effect on viability. Incubation of larvae in gentamicin is effective at reducing microbial bioburden but is deleterious to larval viability