PubMed Health⌕ Search

Biomedical subjects

Sarah Webb

Publications and source records attributed to Sarah Webb.

6 recordsLinked to original sources
PubMed2006

Anti-recoverin antibodies induce an increase in intracellular calcium, leading to apoptosis in retinal cells.

Autoantibodies against recoverin, a Ca2+-binding protein found in patients with cancer-associated retinopathy (CAR syndrome), penetrate retinal cells and induce their apoptosis via a mitochondrial pathway. The goal of this study was to investigate whether the entry of anti-recoverin antibody into E1A.NR3 retinal cells causes a change in intracellular Ca2+. Intracellular Ca2+ was measured using the Ca2+-sensitive fluorescent dye Fura-2 AM in living E1A.NR3 retinal cells treated with anti-recoverin antibody Rec-1, patients' autoantibodies, and control rat and human IgG. The exposure of retinal cells to Rec-1 antibody and to the CAR patients' autoantibodies in vitro caused a significant increase in intracellular Ca2+, while non-specific antibodies did not induce such an effect. Co-treatment of the E1A.NR3 cells with Rec-1 in the presence of nifedipine, a L-type Ca2+ channel blocker, significantly suppressed the increase of Ca2+. Treatment with nifedipine also blocked changes in the anti-apoptotic protein bcl-xL and in expressions of the pro-apoptotic protein bax. Nifedipine-treated cells also showed a decrease in cytosolic cytochrome c release and a decrease in caspase 3 activation, compared to cells treated only with Rec-1 antibody. The increase in the antibody-induced Ca2+ is at least in part dependent on extracellular Ca2+. Nifedipine was found to inhibit the entry of Ca2+ into the cells and to protect them from Rec-1-induced apoptosis. Increased levels of intracellular Ca2+ may lead to retinal dysfunction and degeneration in the CAR syndrome. Our results provide a molecular basis for the use of Ca2+ blockers in the treatment of the CAR syndrome.

Animals↗
PubMed2003

Single primer amplification (SPA) of cDNA for microarray expression analysis.

The potential of expression analysis using cDNA microarrays to address complex problems in a wide variety of biological contexts is now being realised. A limiting factor in such analyses is often the amount of RNA required, usually tens of micrograms. To address this problem researchers have turned to methods of improving detection sensitivity, either through increasing fluorescent signal output per mRNA molecule or increasing the amount of target available for labelling by use of an amplification procedure. We present a novel DNA-based method in which an oligonucleotide is incorporated into the 3' end of cDNA during second-strand cDNA synthesis. This sequence provides an annealing site for a single complementary heel primer that directs Taq DNA polymerase amplification of cDNA following multiple cycles of denaturation, annealing and extension. The utility of this technique for transcriptome-wide screening of relative expression levels was compared to two alternative methodologies for production of labelled cDNA target, namely incorporation of fluorescent nucleotides by reverse transcriptase or the Klenow fragment. Labelled targets from two distinct mouse tissues, adult liver and kidney, were compared by hybridisation to a set of cDNA microarrays containing 6500 mouse cDNA probes. Here we demonstrate, through a dilution series of cDNA derived from 10 micro g of total RNA, that it is possible to produce datasets comparable to those produced with unamplified targets with the equivalent of 30 ng of total RNA. The utility of this technique for microarray analysis in cases where sample is limited is discussed.

Animals↗
PubMed2002

Determinants of consultation rate in patients with anxiety and depressive disorders in primary care.

BACKGROUND: Although it is recognized that anxiety and depression are associated with frequent attendance in primary care, not all patients with these disorders attend frequently. The factors associated with general practice consultation in the important group of patients with anxiety and depressive disorders are not clear. OBJECTIVES: Our aim was to determine prospectively the factors which predict consultation rate in a cohort of patients with anxiety and depressive disorders in primary care. METHODS: A total of 148 adult patients with a depressive, anxiety or panic disorder (DSM-III criteria) were studied prospectively for 6 months to determine the factors which predicted consultation rate during this time. Measures at baseline included: the Psychiatric Assessment Schedule, Hamilton Depression Rating Scale, Life Events and Difficulties Schedule, Clinical Anxiety Scale, details of substance misuse and demographic data. The principal outcome measure was the number of consultations recorded in the GP records over the following 6 months. The variables associated with consultation rate were assessed by multiple regression analysis, with number of consultations as the dependent variable. RESULTS: The median consultation rate during the 6 months of the study was five (range: 1-22). Thirty per cent of the sample consulted seven or more times during the 6 months and 10% consulted 12 or more times. The regression analysis demonstrated that the following variables contributed to the best model: prior consultation rate, past psychiatric history, ongoing social difficulties, current level of alcohol consumption, total psychiatric symptom score and total anxiety score. These variables together accounted for 41% of the variance in consultation rate. CONCLUSION: The detection and rigorous treatment of psychiatric disorder, the provision of social support and interventions for alcohol dependence may help to reduce the frequency of consultation of anxious and depressed patients in primary care. Future research to identify additional variables which explain the major part of the variance in consultation rate may pave the way for novel treatment approaches to the phenomenon of frequent attendance.

Adolescent↗