1,114 research outputs found
An instructional video of RGP fitting modalities
The ultimate goal in fitting rigid gas permeable contacts is to maintain a healthy corneal-lens relationship while satisfying the patient. The fitter may chose between an interpalpebral lens, an under the lid lens, and an upper lid attachment lens modality. The interpalpebral modality is fit at least 0.50D steeper than the flattest keratometer reading and has a diameter between 7.8 and 8.3mm. The base curve chosen for an under the lid fit depends on the size of lens used. Large or small lenses can be fit with this modality depending on the palpebral fissure width. In contrast the upper lid attachment fit uses a diameter larger than 8.8mm and rests under the upper lid. The fitter must understand the relationships between lens diameter, base curves, lens edge and center thickness, and peripheral curves when designing the rigid gas permeable (RGP) lens. The use of fluorescein is an invaluable tool in assessing the fit of a RGP lens and the patient\u27s corneal health. This paper /video will discuss and illustrate these various effects
A Study to Determine if University Athletic Teams in Desert Environments Experience Risky Diet-related Behaviours
Training and competing in desert environments may exacerbate concerns related to disordered eating, supplement use, and hydration in some student athlete populations. A survey administered equitably to both genders solicited self-reported responses from members of 18 different teams over four years from a southwestern United States university athletic program. More than 1,700 athletes responded to 42 items on the questionnaire. Teams, not individual student athletes, were the units of measure for statistical analyses. Initial analysis of results indicated that there were no overt concerns regarding dietary behaviors due to training and competing in the desert environment. Further analysis subjected the team responses to principle component factor analysis and determined the construct validity using Varimax rotation with Kaiser normalization. Six factors were identified which accounted for 93% of total variance associated with reported risky dietary related behaviors among athletic teams. Specifically, the factors contributing to dietary related behavior total variance were; 1) weight loss and exercise issues and practices -47.15%, 2) self-image - 26.00%, 3) hydration - 10.92%, 4) supplement use - 3.85%, 5) disordered eating - 3.70%, and 6) hormonal issues - 1.71%. University athletic programs should use routine assessment of dietary related behaviours, including hydration, to help identify team members practicing risky dietary related behaviours
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Shoot yield drives phosphorus use efficiency in Brassica oleracea and correlates with root architecture traits
The environmental and financial costs of using inorganic phosphate fertilizers to maintain crop yield and quality are high. Breeding crops that acquire and use phosphorus (P) more efficiently could reduce these costs. The variation in shoot P concentration (shoot-P) and various measures of P use efficiency (PUE) were quantified among 355 Brassica oleracea L. accessions, 74 current commercial cultivars, and 90 doubled haploid (DH) mapping lines from a reference genetic mapping population. Accessions were grown at two or more external P concentrations in glasshouse experiments; commercial and DH accessions were also grown in replicated field experiments. Within the substantial species-wide diversity observed for shoot-P and various measures of PUE in B. oleracea, current commercial cultivars have greater PUE than would be expected by chance. This may be a consequence of breeding for increased yield, which is a significant component of most measures of PUE, or early establishment. Root development and architecture correlate with PUE; in particular, lateral root number, length, and growth rate. Significant quantitative trait loci associated with shoot-P and PUE occur on chromosomes C3 and C7. These data provide information to initiate breeding programmes to improve PUE in B. oleracea
Cytosolic chaperones influence the fate of a toxin dislocated from the endoplasmic reticulum
The plant cytotoxin ricin enters target mammalian cells by receptor-mediated endocytosis and undergoes retrograde transport to the endoplasmic reticulum (ER). Here, its catalytic A chain (RTA) is reductively separated from the cell-binding B chain, and free RTA enters the cytosol where it inactivates ribosomes. Cytosolic entry requires unfolding of RTA and dislocation across the ER membrane such that it arrives in the cytosol in a vulnerable, nonnative conformation. Clearly, for such a dislocated toxin to become active, it must avoid degradation and fold to a catalytic conformation. Here, we show that, in vitro, Hsc70 prevents aggregation of heat-treated RTA, and that RTA catalytic activity is recovered after chaperone treatment. A combination of pharmacological inhibition and cochaperone expression reveals that, in vivo, cytosolic RTA is scrutinized sequentially by the Hsc70 and Hsp90 cytosolic chaperone machineries, and that its eventual fate is determined by the balance of activities of cochaperones that regulate Hsc70 and Hsp90 functions. Cytotoxic activity follows Hsc70-mediated escape of RTA from an otherwise destructive pathway facilitated by Hsp90. We demonstrate a role for cytosolic chaperones, proteins typically associated with folding nascent proteins, assembling multimolecular protein complexes and degrading cytosolic and stalled, cotranslocational clients, in a toxin triage, in which both toxin folding and degradation are initiated from chaperone-bound states
Cytosolic chaperones influence the fate of a toxin dislocated from the endoplasmic reticulum
The plant cytotoxin ricin enters target mammalian cells by receptor-mediated endocytosis and undergoes retrograde transport to the endoplasmic reticulum (ER). Here, its catalytic A chain (RTA) is reductively separated from the cell-binding B chain, and free RTA enters the cytosol where it inactivates ribosomes. Cytosolic entry requires unfolding of RTA and dislocation across the ER membrane such that it arrives in the cytosol in a vulnerable, nonnative conformation. Clearly, for such a dislocated toxin to become active, it must avoid degradation and fold to a catalytic conformation. Here, we show that, in vitro, Hsc70 prevents aggregation of heat-treated RTA, and that RTA catalytic activity is recovered after chaperone treatment. A combination of pharmacological inhibition and cochaperone expression reveals that, in vivo, cytosolic RTA is scrutinized sequentially by the Hsc70 and Hsp90 cytosolic chaperone machineries, and that its eventual fate is determined by the balance of activities of cochaperones that regulate Hsc70 and Hsp90 functions. Cytotoxic activity follows Hsc70-mediated escape of RTA from an otherwise destructive pathway facilitated by Hsp90. We demonstrate a role for cytosolic chaperones, proteins typically associated with folding nascent proteins, assembling multimolecular protein complexes and degrading cytosolic and stalled, cotranslocational clients, in a toxin triage, in which both toxin folding and degradation are initiated from chaperone-bound states
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