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Biomedical subjects

I F Purchase

Publications and source records attributed to I F Purchase.

At least 55 records · Page 3Linked to original sources
PubMed1979

Quantitative comparisons of the pulmonary toxicity of tobacco and NSM smoke.

Smoking elicits a panacinar rise in pulmonary alveolar lysosomal activity that is thought to correlate with the irritancy of the smoke. Quantitative image analysis of lung sections stained histochemically for acid phosphatase indicates that tobacco smoke is significantly more irritant than NSM smoke.

Acid Phosphatase↗
PubMed1979

Apocrine secretion in the terminal bronchiole of mouse lung.

The question of the existence of apocrine secretory activity by the Clara cells of the mouse lung terminal bronchiole has been investigated in depth. The overall superiority of 1--2 micrometer plastic sections for light microscopy was demonstrated. The preservation of the anatomy of the terminal bronchiole was shown to be adversely affected by slow killing methods, by post mortem delays before fixation, and by the instillation of fluids via the trachea. The use of collapsed lungs removed from rapidly killed animals is probably the best method for the study of the small bronchioles of the lung. Apocrine secretion takes place as originally described by Clara in 1937. The reason why the phenomenon has received so little attention in the literature is probably because the tracheal or vascular perfusion of fixative, and delays before fixation, all prevent apocrine droplets from being preserved.

Animals↗
PubMed1978

Chromosomal analyses in vinyl chloride-exposed workers.

Chromosomal morphology from cultured peripheral lymphocytes was studied in 81 men; 57 of the men were employed on plants manufacturing vinyl chloride or polyvinylchloride, 19 were on-site controls and 5 were off-site controls. There was a significant increase in chromosomal abnormalities in the exposed workers when compared with the controls. The greatest statistically significant increase in total B and total C cells occurred in autoclave operators, with smaller increases in other job categories. The increase in chromosomal aberrations was correlated with the length of exposure and with a history during the year prior to sampling (1973--1974) of exposure to excursion levels of vinyl chloride. Information on smoking habits was obtained 18 months after blood sampling and a positive correlation between these and total C cell abnormalities was found. There was no positive correlation with various other parameters (bilirubin, platelets, gamma-glutamyltranspeptidase, alkaline phosphatase, alanine transaminase and aspartate transaminase). It was not possible to estimate which of the three parameters (smoking history, length of employment or exposure to excursion levels) was the most important.

Chromosomes↗
PubMed1978

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

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.

Animals↗
PubMed1977

Pulmonary ultrastructure after oral and intravenous dosage of paraquat to rats.

Paraquat was administered to rats by gavage or intravenously at doses which were approximately equitoxic (680 mu. moles/kh and 65 mu. moles/kg respectively) and the lungs examined by light and electron microscopy at intervals up to 48 hours. No significant changes were observed in alveolar endothelial cells at any of the time intervals studied. After intravenous administration the first ultrastructural changes were observed at 4 hr in the type I cells which were less electron dense and contained few organelles. At 8 hr these lesions were more marked and in some places the basement memebrane was denuded. Type II cells were also showing damage to mitochondria and loss of microvilli. After oral dosing, the type and sequence of changes was similar but the first changes were not seen until 22 hr. Intravenous injection of 0-03 micron carbon particles 1 hr before killing showed no significant leakage from the alveolar endothelium. This study provides no morphological evidence that the oedema of the lung caused by paraquat in rats is due to damage to endothelial cells. It appears that, following dosing by the two routes, the difference in interval between dosing and the development of lesions is due to the accumulation of paraquat. Lesions in type I cells therefore occurred when a certain concentration of paraquat is known to be present in the lung. It is suggested that a prime compartment into which paraquat is accumulated is the alveolar epithelial cell.

Animals↗
PubMed1977

Dominant lethal studies with the halogenated olefins vinyl chloride and vinylidene dichloride in male CD-1 mice.

The mutagenic activity of vinyl chloride (VC) and vinylidene dichloride (VDC) at three exposure levels was assessed in fertile male CD-1 mice with the dominant lethal test. Each compound was assessed in a separate study. Male mice were exposed by inhalation to VC at 3000, 10,000, and 30,000 ppm and to VDC at 10, 30, and 50 ppm for 6 hr/day for 5 days. By comparison with control males exposed to air, no mutagenic effects on any maturation stage of spermatogenesis in treated males were detected. There was no significant increase in the number of postimplantational early fetal deaths as shown by the number of females with one or more early deaths or the number of early deaths/pregnancy or the number of early deaths/total implants/pregnancy. There was no evidence of pre-implantational egg losses as indicated by the total implants/pregnant female. There was also no reduction in fertility. (The reduction in fertility at 50 ppm VDC was unproven). The lack of effect was not due to the insensitivity of the system used, since both the VC and VDC study a mutagenic effect was clearly demonstrated in male mice dosed IP with the positive control compounds cyclophosphamide (CTX) and/or ethylmethane sulfonate (EMS). During dosing these animals were housed under similar exposure conditions to those animals exposed to the test substances but with a flow of air through the exposure chambers.Thus, neither VC nor VDC is mutagenic in the mouse at the stated exposure levels as measured by the dominant lethal test.

Animals↗
PubMed1976

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

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.

Alkylating Agents↗
PubMed1976

Dominant lethal studies with paraquat and diquat in male CD-1 mice.

The herbicides paraquat and diquat were tested for dominant lethal activity in male CD-1 mice. No mutagenic effects were detected on any stage of spermatogenesis in treated males if these compounds were administered orally up to 4 mg paraquat/kg/body weight/day of 10 mg diquat/kg/body weight/day for 5 days. There was no increase in the number of post-implantation losses as shown by the number of females with one or more early deaths or number of early deaths/pregnancy or the number of early deaths/total implants/pragnancy. There was no evidence of pre-implantation losses as indicated by the total implants/pregnant female. There was no anti-fertility effect on the treated males as measured by the pregnancy frequency or successful mating frequency. The lack of dominant lethal effect was not due to particular insensitivity of the animals used since such effects were amply demonstrated in mice doses orally on 5 days with ethyl methanesulphonate at 100 mg/kg/body weight/day, or intraperitoneally on one day with cyclophosphamide at 200 mg/kg/body weight.

Animals↗
PubMed1976

Vinyl chloride: dominant lethal studies in male CD-1 mice.

The mutagenic activity of vinyl chloride (VC) at three exposure levels was assessed in fertile male CD-1 mice with the dominant lethal test. Male mice were exposured by inhalation to VC at 3000, 10,000 and 30,000 ppm for 6 h a day for 5 days. By comparison with control males exposed to air, no mutagenic effects on any maturation stage of spermatogeneisis in treated males were detected. There was no significant increase in the number of post-implantational early foetal deaths as shown by the number of females with one or more early deaths or number of early deaths/pregnancy or the number of early deaths/total implants/pregnancy. There was no evidence of pre-implantational egg losses as indicated by the total implants/pregnant female. There was also no reduction in fertility. The lack of effect was not due to the insensitivity of the system used since a dominant lethal effect was clearly demonstated in male mice dosed i.p. with cyclophosphamide (CTX) at 200 mg/kg body weight and ethyl methanesulphonate (EMS) orally at 200 mg/kg body weight once a day for 5 days. During dosing these animals were housed under dimilar exposure conditions to those animals exposed to the test substances but with a flow of air through the exposure chambers. Thus vinyl chloride is not mutagenic in the mouse at the stated exposure levels as measured by the dominant lethal test.

Administration, Oral↗