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Biomedical subjects

S Tipper

Publications and source records attributed to S Tipper.

5 recordsLinked to original sources
PubMed2004

Factors predicting successful DNA recovery from archival cervical smear samples.

Polymerase chain reaction (PCR)-based DNA testing of archival cervical smear slides is a useful method of retrospectively establishing the presence of the human papillomavirus (HPV) in cervical cells. A cellular DNA recovery test is performed in parallel to HPV DNA testing to ensure that sufficient cells are present and purification of sample DNA has been successfully performed. Previous studies have not comprehensively assessed DNA recovery rates in slides older than 13 years. We undertook a study to determine the factors impacting DNA recovery in 436 UK slides dating from 11 to 33 years prior to testing. Overall, a low cellular DNA recovery success rate of 29% was obtained but a strong trend was observed with increasing recovery rates the older the slides (P < 0.001). Recovery rates increased from 22% in the most recent slides collected from 1988 to 1992, to 61% in the oldest slides, collected in 1970-72. It is likely that fixation compounds incorporating acetic acid, introduced in the UK through the 1980s, have compromised subsequent attempts at PCR amplification. These findings emphasize the importance of the original fixation method in the success of DNA recovery from archival smear samples.

DNA, Viral↗
PubMed2001

Collaborating to manage polypharmacy.

DiNCQUMGP (Divisions National Consortium for the Quality Use of Medicines in General Practice) reports on a collaboration between doctors, pharmaceutical companies, government agencies, and medicine users to manage polypharmacy (prescribing multiple medicines to a patient) amongst older people. We have reported the outcomes of our collaboration (improving the Quality Use of Medicines) elsewhere. Here we discuss how we worked together, opened up new opportunities, and learned from one another. The first part of this article outlines a constructive new way of thinking about collaborating, that we argue is fundamentally different from current approaches. The second part describes what we did in the words of those involved.

Cooperative Behavior↗
PubMed1999

Dissociation of attentional processes in patients with focal frontal and posterior lesions.

A location-based ('select-what, respond-where') priming task was used to examine three measures of selective attention (interference (INT), negative priming (NP), and inhibition of return (IOR)) as a function of focal brain pathology and the complexity of target selection. Control subjects showed different patterns of performance for the three attentional measures as a function of complexity, suggesting some independence among INT, NP, and IOR. Brain-damaged subjects showed significant response slowing, as well as a number of lesion-specific attentional abnormalities. Right frontal (including bifrontal) damage resulted in proportionally increased interference related to task complexity. Left posterior damage increased IOR in the most complex task, while left frontal damage reversed the control pattern of IOR as a function of complexity. Right hemisphere (right posterior and right frontal damage) pathology resulted in a virtual loss of negative priming at all levels of task complexity; left and bifrontal damage resulted in diminished NP only related to increases in the complexity of selection. INT, NP, and IOR are mediated by different brain regions and their expression can be modulated by the complexity of the selection task.

Analysis of Variance↗
PubMed1991

Individual differences in cognitive processes: towards an explanation of schizophrenic symptomatology.

A study is reported that examined the relationship between a measure of schizophrenic-like characteristics (schizotypy) in normal subjects and cognitive inhibition. Both repetitive and semantic measures of priming were used. It was found that low schizotypes showed negative priming (i.e. longer reaction times to the re-presentation of initially ignored stimuli) while high schizotypes did not; high schizotypes exhibited semantic facilitation (i.e. shorter reaction times to previously ignored stimuli) but low schizotypes did not. A model is suggested, including both inhibitory and facilitatory processes, which can account for these findings. Theorizing about these processes is of interest as it may shed some light on the mechanisms involved in the specifically cognitive symptoms of schizophrenia.

Adolescent↗