Publications by authors named "Westwood F"

39 Publications

Pathologic changes in blood vessels following administration of an inotropic vasodilator (ICI 153,110) to the rat.

Fundam Appl Toxicol 1990 May;14(4):797-809

Safety of Medicines Department, ICI Pharmaceuticals, Mereside, Macclesfield, Cheshire, United Kingdom.

ICI 153,110 is an inotropic vasodilator compound intended for the treatment of congestive heart failure. It was administered to rats at dose levels of 5, 10, and 250 mg/kg/day for up to 6 months as part of its preclinical development program. Detailed clinical investigations were conducted during the course of the study and histopathological examination took place after 28 days and 182 days of treatment as well as 42 days following cessation of dosing. Changes were identified in blood vessels in the greater proportion of animals from the high dose group, although some of the changes were also observed at lower dose levels. Vascular tissues from a variety of sites were affected, particularly those of the mesentery, splanchnum, heart, testis, and the pampiniform plexus. Early changes characteristic of acute injury such as arterial medial necrosis and inflammation occurred, which were distinguishable from those following chronic administration of the compound where there was a pronounced arterial and venous wall thickening and accompanying plexiform vasculopathy. The essential components contributing to the thickening were a smooth muscle hypertrophy and hyperplasia of the media. At the end of the period following withdrawal of dosing, vascular thickening was still present and arteritis showed an increased incidence relative to that seen at termination of the main test. Systemic hypertension was not detected during these studies. Vasodilation occurring at or near normal blood pressure, resulting in breakdown of vascular autoregulation and excessive critical wall tension, may have been the cause of the pathological changes. Our findings indicate that medial necrosis is an early component in a sequence of adaptive, destructive, and reparative changes not only following a chemically induced perturbation of the hemodynamic status in arteries and veins but also following a shift back to the "normal state" on withdrawal of compound.
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http://dx.doi.org/10.1016/0272-0590(90)90304-3DOI Listing
May 1990

Analysis of cell cultures of 3,4-benzpyrene-treated subcutis and subsequent growth in semi-solid medium.

Br J Cancer 1980 May;41(5):800-8

An in vivo-in vitro implantation model has been used to investigate further the early stages of chemically induced s.c. neoplasia in the mouse. Cell cultures of implant-site tissues from control and 3,4-benzpyrene (BP)-treated animals were found to mirror the in vivo tissue reactions occurring at the time of explantation (Westwood et al., 1979). Cells were classified into 6 different types. The most abundant cell type in later control cultures was of a typical fibroblast morphology. However, a suppression of growth of fibroblast-like cells occurred when BP-treated tissues were explanted, and a selection of growth in favour of the large polygonal Type 5 cells was observed. When grown from BP-treated tissues Type 5 cells were found to be capable of growth in a semi-solid agar medium. Quantitative studies showed that cells capable of growth in agar reached a peak about 4 weeks after implantation, followed by a decline in numbers until the formation of tumours. This observation may result from the parameters regulating the development of chemically induced neoplasia in the subcutis.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2010323PMC
http://dx.doi.org/10.1038/bjc.1980.144DOI Listing
May 1980

Cellular progression of neoplasia in the subcutis of mice after implantation of 3,4-benzpyrene.

Br J Cancer 1979 Jun;39(6):761-72

An implantation model has been used to investigate the cellular progression of chemically induced subcutaneous neoplasia in the mouse. Implantation of 3,4-benzpyrene induced persistent changes in the normal process of connective tissue formation around the implant. Light-microscope and autoradiographic studies have shown a temporal progression from aberrant filter- or muscle-associated cells through proliferative foci to large invasive sarcoma. Electron microscopy revealed that presarcomatous cell foci consisted of one of two different cell types. These were either spindle cells with ultrastructural characteristics similar to foreign-body-induced sarcoma, or cells with the ultrastructural features of rhabdomyosarcoma. The subsequent appearance of two histological groups of sarcoma that were ultrastructurally similar to the cells of the early proliferative foci indicated that both elements may progress to form tumours. However, the constituent cells of both groups of tumours displayed a broad histological and ultrastructural spectrum and the marked similarity between the undifferentiated cells of each suggested that both may have arisen from diverse differentiation of a common pluripotential cell such as the pericyte.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2009991PMC
http://dx.doi.org/10.1038/bjc.1979.130DOI Listing
June 1979

An evaluation of 6 short-term tests for detecting organic chemical carcinogens.

Br J Cancer 1978 Jun;37(6):873-903

A number of tests have been described which are thought to be capable of identifying carcinogens without using the actual induction of cancer as an endpoint. This study compared the performance of 6 such tests on a selection of 120 organic chemicals. The tests studies were: (1) mutation of Salmonella typhimurium; (2) cell transformation; (3) degranulation of endoplasmic reticulum; (4) sebaceous gland suppression; (5) tetrazolium reduction and (6) subcutaneous implant. A further 4 tests were examined briefly, but were not included in the complete evaluation. The chemicals were classified into carcinogens (58) and non-carcinogens (62) on the basis of published experimental data, and into 1 of 4 broad chemical classes. There was considerable variation between tests in their ability to predict carcinogenicity, with the cell-transformation test and the bacterial-mutation test being the most accurate (94% and 93% accurate respectively). These 2 tests were considered to be of general use in screening, since they were clearly more accurate than the others. Statistical consideration of various combinations of these tests showed that the use of cell transformation and bacterial mutation together, provide an advantage over the use of either test alone. The inclusion of the other 4 tests in a screening battery predictably resulted in a great increase in overall inaccuracy and loss of discrimination, even though the detection of carcinogens is improved. All the tests were shown to generate both false positive and false negative results, a situation which may be controlled by the use, where possible, of appropriate chemical-class controls, to identify the test which is optimal for the class of chemical under test. Structural analogy may have a part to play in the rapid detection of environmental carcinogens, and some general guidelines for its use are given.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2009661PMC
http://dx.doi.org/10.1038/bjc.1978.132DOI Listing
June 1978

Evaluation of six short term tests for detecting organic chemical carcinogens and recommendations for their use.

Nature 1976 Dec;264(5587):624-7

Six short term tests for detecting carcinogenicity have been evaluated using 120 compounds, of which half were carcinogens and the rest non-carcinogens. The results obtained indicate that the Ames test and a "cell transformation" assay are both sufficiently sensitive to carcinogenicity, or the lack of it, in the compounds studied to enable them to be employed for detecting potential carcinogens. The consequences of using short term tests under various screening conditions have been explored. In order to have confidence in the results obtained for new or previously untested compounds it is important to use such tests in a carefully controlled manner.
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http://dx.doi.org/10.1038/264624a0DOI Listing
December 1976

Stimulation of cellular ingestion by basic proteins in vitro.

Br J Cancer 1976 Apr;33(4):392-9

The ingestion of carbon and benzpyrene particles in vitro by rat peritoneal macrophages, baby hamster kidney fibroblasts (BHK-21) and mouse L-cells has been shown to be significantly stimulated by the inclusion of histone or polylysine in the culture medium. Parallel studies using methylated bovine albumin did not significantly stimulate carbon or benzpyrene uptake relative to untreated control cultures. Incubation of carbon particles with histone before inclusion in the culture medium of macrophages resulted in the same degree of uptake as in the cultures where carbon and histone were added independently of each other. The implications of these findings to in vivo chemical carcinogenesis are examined.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2025076PMC
http://dx.doi.org/10.1038/bjc.1976.64DOI Listing
April 1976

Postoperative urinary bladder irrigation in the female; a controlled trial.

J R Coll Surg Edinb 1972 Nov;17(6):369-75

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November 1972
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