Identification of a UPC2 Homolog in Saccharomyces cerevisiae and Its Involvement in Aerobic Sterol Uptake

Saccharomyces cerevisiae normally will not take up sterols from the environment under aerobic conditions. A specific mutant, upc2-1, of the predicted transcriptional activator UPC2 (YDR213w) has been recognized as a strain that allows a high level of aerobic sterol uptake. Another predicted transcriptional activator, the YLR228c gene product, is highly homologous to Upc2p. In fact, at the carboxy terminus 130 of the last 139 amino acids are similar between the two proteins. Since these proteins are very similar, the effect of mutations in the YLR228c open reading frame (ORF) was compared with like alterations in UPC2. First, the YLR228c ORF was insertionally inactivated and crossed with various UPC2 constructs. Deletion of YLR228c and UPC2 in combination resulted in nonviability, suggesting that the two proteins have some essential overlapping function. The upc2-1 point mutation responsible for aerobic sterol uptake was duplicated in the homologous carboxy region of the YLR228c ORF using site-directed mutagenesis. This mutation on a high-copy vector resulted in an increase in sterol uptake compared to an isogenic wild-type strain. The combination of both point mutations resulted in the greatest level of aerobic sterol uptake. When the YLR228c point mutation was expressed from a low-copy vector there was little if any effect on sterol uptake. Gas chromatographic analysis of the nonsaponifiable fractions of the various strains showed that the major sterol for all YLR228c and UPC2 combinations was ergosterol, the consensus yeast sterol

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Quantifying Risk Factors for Long-Term Sleep Problems After Burn Injury in Young Adults

Restorative sleep is an important component of quality of life. Disturbances in sleep after burn injury were reported but all based on uncontrolled or nonstandardized data. The occurrence and the effect of long-term sleep problems in young adult burn survivors have not been well defined. This 5-year (2003-2008) prospective multicenter longitudinal study included adults with burn injuries ages 19 to 30 years who completed the Young Adult Burn Outcome Questionnaire (YABOQ) up to 36 months after injury. The items measured 15 patient-reported outcomes including physical, psychological, and social statuses and symptoms such as itch and pain. Scores of these 15 YABOQ outcome domains were standardized to a mean of 50 and a SD of 10 based on an age-matched nonburned reference group of young adults. Sleep quality was assessed using the item 'How satisfied are you now with your sleep,' rated by a 5-point Likert scale. Patients responding with very and somewhat dissatisfied were classified as having sleep dissatisfaction and the remaining as less or not dissatisfied. The associations between sleep dissatisfaction (yes/no) and YABOQ outcome domains were analyzed longitudinally using mixed-effect generalized linear models, adjusted for %TBSA burned, age, gender, and race. Generalized estimating equations were used to take into account correlated error resulting from repeated surveys on each patient over time. One hundred and fifty-two burn survivors participated in the YABOQ survey at baseline and during the follow-up who had at least one survey with a response to the sleep item. Among them, sleep dissatisfaction was twice as prevalent (76/152, 50%) when compared with the nonburned reference group (29/112, 26%). The likelihood of a burn survivor being dissatisfied with sleep was reduced over time after the burn injury. Sleep dissatisfaction following burns was significantly associated, in a dose-dependent manner, with increasing burn size (P = .001). Better sleep was associated with better outcomes in all domains (P < .05) except Fine Motor Function, and this association was significantly more apparent in the longer term compared with the shorter term with the same domains (P < .05). Dissatisfaction with sleep is highly prevalent following burn injuries in young adults. Lower satisfaction with sleep is associated with poorer scores in nearly all quality of life measures. Satisfaction with sleep should be addressed during the long-term clinical follow-up of young adults with burn injuries. Further research should be undertaken to understand the components of sleep quality that are important to burn survivors and which ones might be modified and tested in future intervention studies