Publications by authors named "Purcell S"

Modulation of glutathione has been proposed as a mechanism to alter the efficacy and toxicity of chemotherapeutic agents. We investigated in vitro cytoenhancement of chemotherapy toxicity by reducing cellular glutathione levels with L-buthionine-[S,R]-sulfoximine (BSO), and chemoprotection with small molecular weight sulfur-containing agents that mimic or replace glutathione. Cytotoxicity, caspase-2 enzymatic activity, and in situ DNA staining for apoptosis were assessed in cultured human small cell lung carcinoma cells and fibroblasts.

View Article and Find Full Text PDF

Optimal design of quantitative-trait loci (QTL) mapping studies requires a precise understanding of the power of QTL linkage versus QTL association analysis, under a range of different conditions. In this article, we investigate the power of QTL linkage and association analyses for simple random sibship samples, under the variance-components model proposed by Fulker et al. After a brief description of an extension of this variance-components model, we show that the powers of both linkage and association analyses are crucially dependent on the proportion of phenotypic variance attributable to the QTL.

View Article and Find Full Text PDF

The authors investigated the etiology of several measures of cognitive delay. Verbal (V) and performance (P) abilities were assessed in over 3,000 pairs of 2-year-old twins. Group-differences heritability for general delay (the lowest 5% of the V and P composite) was 35%.

View Article and Find Full Text PDF

Previous work suggests that most clinically significant language difficulties in children do not result from acquired brain lesions or adverse environmental experiences but from genetic factors that presumably influence early brain development. We conducted the first twin study of language delay to evaluate whether genetic and environmental factors at the lower extreme of delayed language are different from those operating in the normal range. Vocabulary at age two was assessed for more than 3000 pairs of twins.

View Article and Find Full Text PDF

A 47-year-old woman presented with a long-standing history of an erythema multiforme-like eruption in association with lupus erythematosus. Unusual laboratory and immunologic findings were consistent with a diagnosis of Rowell's syndrome, which includes lupus erythematosus in association with erythema multiforme-like skin lesions, a speckled antinuclear antibody pattern, and a positive rheumatoid factor. We believe that our patient meets the criteria for this rarely reported entity.

View Article and Find Full Text PDF

Lichen sclerosus et atrophicus is an uncommon disease which appears to be multifactorial in aetiology. We describe a case of a young woman with CREST syndrome (calcinosis, Raynaud's phenomenon, oesophageal dysfunction, sclerodactyly and telangiectasia) who has a documented family history of two sisters with lichen sclerosus et atrophicus. She presented with vulvar pruritus in association with dyspareunia, and biopsy of atrophic white vulvar lesions was consistent with lichen sclerosus et atrophicus.

View Article and Find Full Text PDF

When overexpressed in Xenopus embryos, Xwnt-1, -3A, -8 and -8b define a functional class of Wnts (the Wnt-1 class) that promotes duplication of the embryonic axis, whereas Xwnt-5A, -4, and -11 define a distinct class (the Wnt-5A class) that alters morphogenetic movements (Du, S., S. Purcell, J.

View Article and Find Full Text PDF

Wnts are secreted signaling factors which influence cell fate and cell behavior in developing embryos. Overexpression in Xenopus laevis embryos of a Xenopus Wnt, Xwnt-8, leads to a duplication of the embryonic axis. In embryos ventralized by UV irradiation, Xwnt-8 restores expression of the putative transcription factor goosecoid, and rescues normal axis formation.

View Article and Find Full Text PDF

Narratives from three studies differing in subject pools, elicitation procedures, and story content were analyzed using seven variables hypothesized to measure a variety of language abilities used in narrative production. Two questions were addressed: (a) To what extent did multiple variables represent common factors? and (b) To what extent did these variables distinguish children with language disorder from their nondisordered peers? Results indicated that: (a) The seven variables represented two factors; Factor I measured global organization of content (i.e.

View Article and Find Full Text PDF

The cutaneous manifestations of human immunodeficiency virus infection include papulosquamous diseases, viral and fungal infections, and neoplastic disorders. Eczematous photosensitivity disorders have been reported in patients infected with the human immunodeficiency virus. We describe a patient with advanced acquired immunodeficiency syndrome who developed photodistributed hypertrophic lichen planus.

View Article and Find Full Text PDF

Experiments investigated whether infants infer that a hidden, freely moving object will move continuously and smoothly. Infants aged 6 and 10 months, like the 4-month-old infants in previous experiments, inferred that the object's path would be connected and unobstructed, in accord with the principle of continuity. In contrast, 4- and 6-month-old infants did not appear to infer that the object's path would be smooth, in accord with the principle of inertia.

View Article and Find Full Text PDF

Ceratophrys ornata, the Argentinean horned frog, has a significantly different pattern of early morphogenesis than does the most studied amphibian, Xenopus laevis. Time-lapse videomicroscopy, scanning electron microscopy, histological sections and lineage tracers have shown that, in C. ornata, some prospective notochord, somite and tailbud mesoderm cells leave the surface epithelium of the archenteron by ingression.

View Article and Find Full Text PDF

The self-initiated repairs produced by 14 normal-language and 14 language-disordered children during a story retelling task are described. When grammatical repairs and repairs to text meaning were analysed, no group differences were found for either repair type. Both groups initiated significantly more repairs to text meaning.

View Article and Find Full Text PDF