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Sarah Purdy

Publications and source records attributed to Sarah Purdy.

11 recordsLinked to original sources
PubMed2006

Genetic variation suggests interaction between cold acclimation and metabolic regulation of leaf senescence.

The extent to which leaf senescence is induced by nitrogen deficiency or by sugar accumulation varies between natural accessions of Arabidopsis (Arabidopsis thaliana). Analysis of senescence in plants of the Bay-0 x Shahdara recombinant inbred line (RIL) population revealed a large variation in developmental senescence of the whole leaf rosette, which was in agreement with the extent to which glucose (Glc) induced senescence in the different lines. To determine the regulatory basis of genetic differences in the Glc response, we investigated changes in gene expression using Complete Arabidopsis Transcriptome MicroArray (CATMA) analysis. Genes whose regulation did not depend on the genetic background, as well as genes whose regulation was specific to individual RILs, were identified. In RIL 310, a line that does not show the typical senescence response to Glc, stress response genes, especially those responding to cold stress, were induced by Glc. We therefore tested whether cold acclimation delays senescence by reducing sugar sensitivity. In cold-acclimated plants, leaf senescence was severely delayed and Glc did not induce the typical senescence response. Together, our results suggest that cold acclimation extends rosette longevity by affecting metabolic regulation of senescence, thereby allowing vernalization-dependent plants to survive the winter period. The role of functional chloroplasts and of nitrogen and phosphate availability in this regulation is discussed.

Acclimatization↗
PubMed2006

Acne.

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Acne Vulgaris↗
PubMed2006

Effectiveness of nurse-led brief alcohol intervention: a cluster randomized controlled trial.

AIM: This paper reports an evaluation of the effectiveness and cost-effectiveness of nurse-led screening and brief intervention in reducing excessive alcohol consumption among patients in primary health care. BACKGROUND: Excessive alcohol consumption is a major source of social, economic and health problems. However, such consumption is responsive to brief alcohol intervention. To date, brief intervention research in primary health care has focused on general practitioner-led interventions, and there is only circumstantial evidence of effectiveness in nurse-led interventions. However, nurses are increasingly taking a lead in health promotion work in primary care. METHODS: A pragmatic cluster-randomized controlled trial was carried out between August 2000 and June 2003 to evaluate the effects of a brief intervention compared with standard advice (control condition). A total of 40 general practice clusters (intervention = 21 and control = 19) recruited 127 patients (intervention = 67 and control = 60) to the trial. Excessive consumption was identified opportunistically via the Alcohol Use Disorders Identification Test. After baseline assessment, patients received either a 5-10 minutes brief intervention using the 'Drink-Less' protocol or standard advice (control condition). Follow-up occurred at 6 and 12 months postintervention. RESULTS: Analysis of variance weighted for cluster size revealed no statistically significant differences between intervention and control patients at follow up. A majority of patients in both conditions reduced their alcohol consumption between assessment and subsequent measurement. Economic analysis suggested that the brief intervention led to no statistically significant changes in subsequent health service resource use relative to standard treatment. CONCLUSION: The brief intervention evaluated in this trial had no effect over standard advice delivered by nurses in primary health care. However, there was a reduction in excessive drinking across both arms of the trial over time. Due to nurse drop-out, this trial was significantly underpowered. Future research should explore barriers to nurses' involvement in research trials, particularly with an alcohol focus. A larger trial is required to evaluate the effectiveness of nurse-led screening and brief alcohol intervention in primary care.

Adult↗
PubMed2006

Acne vulgaris.

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Acne Vulgaris↗
PubMed2005

The role of sugars in integrating environmental signals during the regulation of leaf senescence.

Although leaf senescence results in a loss of photosynthetic carbon fixation, the senescence-dependent release of nutrients, especially of nitrogen, is important for the growth of young leaves and for reproduction. Environmental regulation of senescence is therefore a vital factor in the carbon and nitrogen economy of plants. Leaf senescence is a highly plastic trait that is affected by a range of different environmental factors including light, nutrient supply, CO2 concentration, and abiotic and biotic stress. In this review, the focus is on the impact of environmental conditions on sugar accumulation and sugar signalling during senescence. By signalling a high availability of carbon relative to nitrogen in the old leaves, sugar accumulation can trigger leaf senescence. Sugar-induced senescence is therefore particularly important under low nitrogen availability and may also play a role in light signalling. Whether or not sugars are involved in regulating the senescence response of plants to elevated CO2 remains unresolved. Senescence can be delayed or accelerated in elevated CO2 and no clear relationship between sugar accumulation and senescence has been found. Plasticity in the response to environmental factors, such as daylength and sugar accumulation, varies between different Arabidopsis accessions. This natural variation can be exploited to analyse the genetic basis of the regulation of senescence and the consequences for growth and fecundity. Different evolutionary strategies, i.e. early senescence combined with a high reproductive effort or late senescence combined with a low reproductive effort, may be an important adaptation of Arabidopsis accessions to their natural habitat.

Acclimatization↗
PubMed2005

Characterization of markers to determine the extent and variability of leaf senescence in Arabidopsis. A metabolic profiling approach.

Comparison of the extent of leaf senescence depending on the genetic background of different recombinant inbred lines (RILs) of Arabidopsis (Arabidopsis thaliana) is described. Five RILs of the Bay-0 x Shahdara population showing differential leaf senescence phenotypes (from early senescing to late senescing) were selected to determine metabolic markers to discriminate Arabidopsis lines on the basis of senescence-dependent changes in metabolism. The proportion of gamma-aminobutyric acid, leucine, isoleucine, aspartate, and glutamate correlated with (1) the age and (2) the senescence phenotype of the RILs. Differences were observed in the glycine/serine ratio even before any senescence symptoms could be detected in the rosettes. This could be used as predictive indicator for plant senescence behavior. Surprisingly, late-senescing lines appeared to mobilize glutamine, asparagine, and sulfate more efficiently than early-senescing lines. The physiological basis of the relationship between leaf senescence and flowering time was analyzed.

Amino Acids↗
PubMed2005

Acne vulgaris.

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Acne Vulgaris↗
PubMed2004

Interactions of abscisic acid and sugar signalling in the regulation of leaf senescence.

Leaf senescence can be triggered by a high availability of carbon relative to nitrogen or by external application of abscisic acid (ABA). Most Arabidopsis mutants with decreased sugar sensitivity during early plant development are either ABA insensitive (abi mutants) or ABA deficient (aba mutants). To analyse the interactions of carbon, nitrogen and ABA in the regulation of senescence, wild-type Arabidopsis thaliana (L.) Heynh. and aba and abi mutants were grown on medium with varied glucose and nitrogen supply. On medium containing glucose in combination with low, but not in combination with high nitrogen supply, senescence was accelerated and sucrose, glucose and fructose accumulated strongly. In abi mutants that are not affected in sugar responses during early development (abi1-1 and abi2-1), we observed no difference in the sugar-dependent regulation of senescence compared to wild-type plants. Similarly, senescence was not affected in the sugar-insensitive abi4-1 mutant. In contrast, the abi5-1 mutant did exhibit a delay in senescence compared to its wild type. As ABA has been reported to induce senescence and ABA deficiency results in sugar insensitivity during early development, we expected senescence to be delayed in aba mutants. However, the aba1-1 and aba2-1 mutants showed accelerated senescence compared to their wild types on glucose-containing medium. Our results show that, in contrast to sugar signalling in seedlings, ABA is not required for the sugar-dependent induction of leaf senescence. Instead, increased sensitivity to osmotic stress could have triggered early senescence in the aba mutants.

Abscisic Acid↗
PubMed2003

Presentation and management of acne in primary care: a retrospective cohort study.

BACKGROUND: Acne is the most common skin disorder in young people, affecting up to 80% of teenagers. AIMS: To ascertain the incidence, prevalence, demographic distribution and severity of acne in primary care and to document the management of these patients for a two-year period after presentation. DESIGN OF STUDY: Retrospective cohort study using data from the medical records of 798 patients who had been treated for acne during a one-year identification period. SETTING: Fourteen general practices in a mixed urban area in north-east England. METHOD: Patients aged 13 to 25 years who had acne were identified from computerised practice medical records using diagnostic codes and medication records. The medical records of these patients were then hand-searched for data for two years after presentation. RESULTS: Data were collected for 798 patients from 14 practices. The prevalence of acne in 13- to 25-year-olds was 3.1%, and the incidence was 1.6%. The ratio of male to female patients with acne was 1:1.02. Median age at presentation was 15 years for male subjects and 16 years for female subjects. Recording of site and severity was rare (18.3%). In total, 55% of patients had two or more different prescriptions for acne, 21% of patients had six or more consultations during the two-year follow-up period, and 8.5% were referred to a dermatologist. CONCLUSION: Given previous estimates of community prevalence, it is clear that the majority of young people with acne do not present to primary care. These findings have implications for the provision of effective and appropriate health care for young people with acne.

Acne Vulgaris↗