The PKC, HOG and Ca2+ signalling pathways co-ordinately regulate chitin synthesis in Candida albicans

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Individual chitin synthase enzymes synthesize microfibrils of differing structure at specific locations in the Candida albicans cell wall

The shape and integrity of fungal cells is dependent on the skeletal polysaccharides in their cell walls of which β(1,3)-glucan and chitin are of principle importance. The human pathogenic fungus Candida albicans has four genes, CHS1, CHS2, CHS3 and CHS8, which encode chitin synthase isoenzymes with different biochemical properties and physiological functions. Analysis of the morphology of chitin in cell wall ghosts revealed two distinct forms of chitin microfibrils: short microcrystalline rodlets that comprised the bulk of the cell wall; and a network of longer interlaced microfibrils in the bud scars and primary septa. Analysis of chitin ghosts of chs mutant strains by shadow-cast transmission electron microscopy showed that the long-chitin microfibrils were absent in chs8 mutants and the short-chitin rodlets were absent in chs3 mutants. The inferred site of chitin microfibril synthesis of these Chs enzymes was corroborated by their localization determined in Chsp–YFP-expressing strains. These results suggest that Chs8p synthesizes the long-chitin microfibrils, and Chs3p synthesizes the short-chitin rodlets at the same cellular location. Therefore the architecture of the chitin skeleton of C. albicans is shaped by the action of more than one chitin synthase at the site of cell wall synthesis

Visual characteristics of elderly night drivers in the Salisbury Eye Evaluation Driving Study

PURPOSE. To characterize visual factors among those who continue to drive and those who restrict night driving in the elderly population. METHODS. The Salisbury Eye Evaluation Driving Study (SEEDS) is a study of vision, cognition, and driving behaviors of older drivers living in the greater Salisbury, Maryland, metropolitan area. Patients were recruited from listings in the Department of Motor Vehicle Administration. Data are reported from two visits conducted 2 years apart. Night driving was assessed using a real-time driving assessment tool, the Driving Monitor System. Night driving was defined by the presence of at least one episode of driving at night during a 5-day time period (seasonally adjusted). Participants also underwent a battery of cognitive and visual function testing including distance acuity, contrast sensitivity, and visual fields. Logistic regression was used to model factors associated with night driving. RESULTS. Complete data were available for 990 of the 1080 participants (92%) attending both visits; 41% of participants were driving at night in each visit. Those who were younger (P < 0.001), male (P < 0.001), and had better measures of cognitive (P 1/4 0.007) and visual function were observed driving at night, whereas those who were older, female, and had poorer measures of cognitive and visual function restricted their night driving behavior. An association was observed between depressive symptoms and less night driving in females (P 1/4 0.003). In multivariate analysis, better contrast sensitivity (odds ratio [OR] 1.18, 95% confidence interval [CI] 1.02-1.36, P 1/4 0.02) and visual field detection (OR 1.21, 95% CI 1.00-1.47, P 1/4 0.05) were associated with driving at night. Visual acuity was not found to be significantly related to night driving (OR 1.08, 95% CI 0.95-1.18, P 1/4 0.12). CONCLUSIONS. Restricting driving at night is a multifactorial behavior that has a vision component, notably poor contrast sensitivity, and some loss of visual fields

Maximizing the entanglement of two mixed qubits

Two-qubit states occupy a large and relatively unexplored Hilbert space. Such states can be succinctly characterized by their degree of entanglement and purity. In this letter we investigate entangled mixed states and present a class of states that have the maximum amount of entanglement for a given linear entropy.Comment: 4 pages, 3 figure

Multipartite entangled coherent states

We propose a scheme for generating multipartite entangled coherent states via entanglement swapping, with an example of a physical realization in ion traps. Bipartite entanglement of these multipartite states is quantified by the concurrence. We also use the $N$--tangle to compute multipartite entanglement for certain systems. Finally we establish that these results for entanglement can be applied to more general multipartite entangled nonorthogonal states.Comment: 7 pages, two figures. We added more detail discussions on the generation of multipartite entangled coherent states and multipartite entangelemen

Predictors of lane-change errors in older drivers

OBJECTIVES: To determine the factors that predict errors in executing proper lane changes among older drivers. DESIGN: Cross-sectional analysis of data from a longitudinal study. SETTING: Maryland's Eastern Shore. PARTICIPANTS: One thousand eighty drivers aged 67 to 87 enrolled in the Salisbury Eye Evaluation Driving Study. MEASUREMENTS: Tests of vision, cognition, health status, and self-reported distress and a driving monitoring system in each participant's car, used to quantify lane-change errors. RESULTS: In regression models, measures of neither vision nor perceived stress were related to lane-change errors after controlling for age, sex, race, and residence location. In contrast, cognitive variables, specifically performance on the Brief Test of Attention and the Beery-Buktenicka Test of Visual-Motor Integration, were related to lane-change errors. CONCLUSION: The current findings underscore the importance of specific cognitive skills, particularly auditory attention and visual perception, in the execution of driving maneuvers in older individuals

Sex differences in cognition in healthy elderly individuals

Sex differences in patterns of cognitive test performance have been attributed to factors, such as sex hormones or sexual dimorphisms in brain structure, that change with normal aging. The current study examined sex differences in patterns of cognitive test performance in healthy elderly individuals. Cognitive test scores of 957 men and women (age 67-89), matched for overall level of cognitive test performance, age, education, and depression scale score, were compared. Men and women were indistinguishable on tests of auditory divided attention, category fluency, and executive functioning. In contrast, women performed better than men on tests of psychomotor speed and verbal learning and memory, whereas men outperformed women on tests of visuoconstruction and visual perception. Our finding that the pattern of sex differences in cognition observed in young adults is observed in old age has implications for future studies of both healthy elderly individuals and of those with cognitive disorders

Visual and cognitive deficits predict stopping or restricting driving: The salisbury eye evaluation driving study (SEEDS)

PURPOSE. To determine the visual and other factors that predict stopping or restricting driving in older drivers. METHODS. A group of 1425 licensed drivers aged 67 to 87 years, who were residents of greater Salisbury, participated. At 1 year after enrollment, this group was categorized into those who had stopped driving, drove only within their neighborhood, or continued to drive beyond their neighborhood. At baseline, a battery of structured questionnaires, vision, and cognitive tests were administered. Multivariate analysis determined the factors predictive of stopping or restricting driving 12 months later. RESULTS. Of the 1425 enrolled, 1237 (87%) were followed up at 1 year. Excluding those who were already limiting their driving at baseline (n = 35), 1.5% (18/1202) had stopped and 3.4% (41/1202) had restricted their driving. The women (odds ratio [OR], 4.01; 95% confidence interval [CI], 2.05- 8.20) and those who prefer to be driven (OR, 3.91; 95% CI, 1.91- 8.00) were more likely to stop or restrict driving. Depressive symptoms increased likelihood of restricting or stopping driving (OR, 1.08; 95% CI, 1.009 -1.16 per point Geriatric Depression Scale). Slow visual scanning and psychomotor speed (Trail Making Test, Part A: OR, 1.02; 95% CI, 1.01-1.03), poor visuoconstructional skills (Beery-Buktenica Test of Visual Motor Integration: OR, 1.14; 95% CI, 1.05-1.25), and reduced contrast sensitivity (OR, 1.15; 95% CI, 1.03-1.28) predicted stopping or reducing driving. Visual field loss and visual attention were not associated. The effect of vision on changing driving behavior was partially mediated by cognition, depression, and baseline driving preferences. CONCLUSIONS. In this cohort, contrast sensitivity and cognitive function were independently associated with incident cessation or restriction of driving space. These data suggest drivers with functional deficits make difficult decisions to restrict or stop driving

Urban and rural differences in older drivers' failure to stop at stop signs

Our purpose was to determine visual and cognitive predictors for older drivers' failure to stop at stop signs. 1425 drivers aged between ages 67 and 87 residing in Salisbury Maryland were enrolled in a longitudinal study of driving. At baseline, the participants were administered a battery of vision and cognition tests, and demographic and health questionnaires. Five days of driving data were collected with a Driving Monitoring System (DMS), which obtained data on stop signs encountered and failure to stop at stop signs. Driving data were also collected 1 year later (round two). The outcome, number of times a participant failed to stop at a stop sign at round two, was modeled using vision and cognitive variables as predictors. A negative binomial regression model was used to model the failure rate. Of the 1241 who returned for round two, 1167 drivers had adequate driving data for analyses and 52 did not encounter a stop sign. In the remaining 1115, 15.8% failed at least once to stop at stop signs, and 7.1% failed to stop more than once. Rural drivers had 1.7 times the likelihood of not stopping compared to urban drivers. Amongst the urban participants, the number of points missing in the bilateral visual field was significantly associated with a lower failure rate. In this cohort, older drivers residing in rural areas were less likely to stop at stop-sign intersections than those in urban areas. It is possible that rural drivers frequent areas with less traffic and better visibility, and may be more likely to take the calculated risk of not stopping. In this cohort failure to stop at stop signs was not explained by poor vision or cognition. Conversely in urban areas, those who have visual field loss appear to be more cautious at stop signs