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Biomedical subjects

P R Simpson

Publications and source records attributed to P R Simpson.

14 recordsLinked to original sources
PubMed1998

Platinum concentrations in urban road dust and soil, and in blood and urine in the United Kingdom.

Increasing Pt concentrations from vehicle catalysts have been reported from a number of countries. Analysis of Pt and Pd in soils and road dusts taken from areas of high and low traffic flows in SE England show concentrations of Pt in the range < 0.30-40.1 ng g-1 and Pd in the range < 2.1-57.9 ng g-1. Higher concentrations of Pt are associated with high traffic densities. Samples taken from streets of lower traffic flows were found to contain the lower concentrations of the ranges. Pilot studies of Pt concentrations in blood and urine using ICP-MS have been carried out. Platinum concentrations in whole blood were: precious metal workers, 780-2170, mean 1263 pmol l-1 (0.152-0.423, mean 0.246 microgram l-1); motorway maintenance workers, 645-810, mean 744 pmol l-1 (0.126-0.158, mean 0.145 microgram l-1); Imperial College staff, 590-713, mean 660 pmol l-1 (0.115-0.139, mean 0.129 microgram l-1). Platinum concentrations in urine in pmol Pt per mmol creatinine were: precious metal workers, 122-682, mean 273 [0.21-1.18, mean 0.47 microgram Pt (g creatinine)-1]; motorway maintenance workers, 13-78, mean 33.7 [0.022-0.135, mean 0.058 microgram Pt (g creatinine)-1]; Imperial College staff, 28-130, mean 65.6 [0.048-0.224, mean 0.113 microgram Pt (g creatinine)-1]. Detection limits were 0.03 microgram l-1 for both blood and urine. The possible health effects of increasing Pt in the environment are discussed. Platinum provides an excellent example of the significance of speciation in metal toxicity. Platinum allergy is confined to a small group of charged compounds that contain reactive ligand systems, the most effective of which are chloride ligand systems. Metallic Pt is considered to be biologically inert and non allergenic and since the emitted Pt is probably in the metallic or oxide form, the sensitising potential is probably very low. Platinum from road dusts, however, can be solubilised, and enter waters, sediments, soils and the food chain. There is at present no evidence for any adverse health effects from Pt in the general environment, particularly allergic reactions.

Air Pollutants↗
PubMed1997

Quantification of hepatitis B virus DNA using competitive PCR and a scintillation proximity assay.

A rapid assay for the quantification of hepatitis B virus DNA in human serum was developed. The principle of the method combines competitive polymerase chain reaction (cPCR) (for the controlled amplification of hepatitis B virus DNA) and scintillation proximity assay (SPA) technology (for rapid detection and quantitation of PCR products). It also incorporates a reproducible and simple method for the preparation of serum DNA suitable for PCR amplification. The assay has a better linear dynamic range than traditional methods that use 32P to detect PCR products. It was applied to a range of hepatitis B virus (HBV) surface antigen positive (HBsAg + ) sera, and shown to be more sensitive than a commercially available HBV DNA kit.

DNA, Viral↗
PubMed1993

Osteoblastoma of the nasal cavity.

The clinicopathological features of a rare case of osteoblastoma of the nasal cavity arising from the nasal turbinate are reported and compared with four reported cases of osteoblastoma with nasal cavity involvement. Two of the five tumours involved the nasal cavity and paranasal sinuses. The remaining three tumours were confined in the nasal cavity; one arose from nasal bone and two from nasal turbinate periosteum. Four tumours were successfully treated with local excision. One tumour recurred locally after excision; the recurrence was apparently controlled by further local excision.

Adult↗
PubMed1990

Variation among the dispersed (GATA)n sequences in Drosophila melanogaster.

Five nonallelic copies of the dispersed (GATA)n repeated sequence of Drosophila melanogaster (referred to as GATA elements) have been sequenced and analysed. The GATA elements range in size from 111 to 444 bp, consisting predominantly of tandemly repeated GATAs, interspersed with variants of the subunit. The types and distributions of these variants are consistent with the hypothesis that they have arisen by a random accumulation of point mutations (substitutions, deletions, and insertions) in pure (GATA)n sequences. Duplications or deletions of the GATA subunit, and of GATA variants, have also probably occurred, as a result of either unequal crossing-over or slipped-strand mispairing. Evidence for duplication (deletion) has been obtained from a comparison of two allelic GATA elements isolated from different populations. GATA elements, in common with other dispersed, simple repeats, are probably highly variable in length.

Animals↗
PubMed1990

Adenomatoid tumor of the adrenal gland.

An adenomatoid tumor of the adrenal gland is presented. The tumor was discovered in a patient with hypertension and was clinically mistaken for a pheochromocytoma. This is the first reported case, to my knowledge, of an adenomatoid tumor within the adrenal gland, with the exception of one previous article in which the lesion was mistaken for a lymphangioma. This case illustrates that adenomatoid tumors can rarely occur in extragenital locations, even in regions presumably devoid of mesothelial cells.

Adrenal Gland Neoplasms↗
PubMed1988

5S rRNA genes in Pisum: sequence, long range and chromosomal organization.

We have employed a combination of techniques to examine the organization of pea 5S rRNA genes. These include the analysis of length variant interspersion patterns in cosmid clones, sequence analysis, Southern analysis of both conventional gels and field inversion gels and in situ hybridization. From these analyses we conclude that the 5S rRNA genes of pea are arranged in three major tandem arrays which are represented by three large EcoRI fragments and that these correspond to the three sites of in situ hybridization in the haploid pea complement.

Base Sequence↗
PubMed1986

Congenital hybrid basal cell adenoma--adenoid cystic carcinoma of the salivary gland.

A congenital parotid gland tumor involving the facial nerve was excised, revealing histologic and ultrastructural features of a basal cell adenoma and adenoid cystic carcinoma. An asynchronous regional metastasis was successfully eradicated with adriamycin. Seven other similar appearing tumors occurring in neonates are documented in the literature and serve to establish this tumor as a clinicopathologic entity. The surrounding parotid gland had "dysplastic" changes attributed to obstruction during morphogenesis.

Adenoma↗
PubMed1981

Systemic embolization as a complication of transhepatic venography.

Many patients with cirrhosis and portal hypertension demonstrate a right-to-left shunt, caused by development of anastomoses connecting the high-pressure periesophageal veins with the low-pressure bronchial and/or pulmonary veins at the level of the pulmonary hili. These anastomoses from the pathway by which small Gelfoam particles injected into the coronary or short gastric veins may embolize the systemic arterial circulation. Such embolization could have serious consequences, but reports of such complications have not been found by the authors.

Adult↗
PubMed1978

Choice of screening tests.

In this paper, we consider one of the decisions that have to be made about a screening programme: which type of test to use. Our study shows that knowledge of the sensitivities, specificities, and costs of alternative tests is an inadequate basis for the choice of test. The monetary values of the different possible results of the test must also be estimated, or judgements made about the likely magnitude of these values. If judgements have to be made, they should be explicit, because different individuals are likely to judge differently, and their opinions will critically affect the choice of test.

Breast Neoplasms↗