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Biomedical subjects

P Archer

Publications and source records attributed to P Archer.

25 records · Page 2Linked to original sources
PubMed1985

Development of a standard protocol for in vitro cytogenetic testing with Chinese hamster ovary cells: comparison of results for 22 compounds in two laboratories.

A major problem of cytogenetics testing in mammalian cells is lack of agreement of results among laboratories. Our objective was to develop a sensitive in vitro test protocol that was applicable to large-scale chemical screening and yielded comparable results in two laboratories. We used sister chromatid exchange (SCE) and chromosome aberration (CAb) tests in Chinese hamster ovary (CHO) cells. The initial protocol used standard cell densities, medium, batch of rat liver S9 for metabolic activation; positive, negative, and solvent controls; staining and scoring techniques; and fixation times. Treatment without S9 was for 8-12 hr (CAb) or 26 hr (SCE), and with S9 for 2 hr in serum-free medium. Bromodeoxyuridine (BrdUrd) (10 microM) was added to SCE cultures only, 2 hr after addition of the test chemical. Doses were based on the 50% toxicity level in a preliminary test of cell survival 24 hr after treatment. One hundred cells (CAb) or 50 cells (SCE) were scored from each control and from five dose levels. Five clastogens were tested in the first two-laboratory comparison: mitomycin-C, triethylenemelamine, N-methyl-N'-nitro-N-nitrosoguanidine, cyclophosphamide, and benzo(alpha)pyrene. There was quite good agreement between laboratories. Seventeen compounds were then tested "blind" in the two laboratories. As testing proceeded, some discrepancies occurred between the laboratories, and the protocol was modified in attempts to improve the resolution of marginal responses and make dose selection more consistent. The preliminary test for cell survival was omitted. A 10(5) dose range in a half-log series was tested, and cells were scored at the highest dose at which sufficient mitotic cells were obtained, and at the next two lower doses. By delaying fixation times, SCE and CAb were scored at doses that inhibited cell cycle progression. This protocol gave comparable results in the two laboratories in many cases and by testing up to a maximum dose, limited by solubility and/or toxicity, should detect a high proportion of clastogens and SCE inducers.

Animals↗
PubMed1984

Studies on human lactation. I. Within-feed and between-breast variation in selected components of human milk.

Within-feed and between-breast differences in the concentrations of sodium, potassium, chloride, calcium, magnesium, lipid, protein, lactose, glucose, urea nitrogen, creatinine, zinc, and copper were examined in milk samples from 10 women. The average lipid content doubled in the interval from the beginning of the feed to the end. The composition of the aqueous phase of milk, as determined by the major osmotically active constituents, did not vary significantly within the feed. For these components as well as for lipid a small mid-feed sample of milk gave the same mean composition as the pooled, pumped contents of one breast suggesting that such a sample is adequate for determination of milk composition in population studies. Sporadic, inconsistent differences in the composition of the milk from the right and left breasts were observed. It is suggested that mastitis may contribute to these differences. It is recommended that samples routinely be taken from both breasts and analyzed for sodium and chloride to rule out episodes of mastitis or other local phenomena which sporadically alter milk composition.

Adolescent↗
PubMedDate not supplied

Chromosome aberrations in individuals occupationally exposed to ethylene oxide, and in a large control population.

Chromosome aberration frequencies in 61 employees potentially exposed to ethylene oxide (ETO) were compared with those in unexposed control groups. We studied 3 worksites with differing historical ambient levels of ETO. Within worksites, groups were classified as high potential exposed, low potential exposed, or controls. Further control groups including an off-site community control group were added to give a total of 304 control individuals. Blood samples were drawn several times over a 24-month period. Aberrations were analyzed in 100 cells per sample after culture for 48-51 h. Worksites I, II and III respectively represented increasing levels of potential ETO exposure. At worksites I and II, no consistent differences in aberration frequencies were found among groups. At worksite III aberration frequencies in potentially exposed individuals were significantly increased compared with controls. The frequencies of cells with aberrations were 5.6% for the 2 individuals in the high potential exposure category and 2.6% for 23 persons in the low potential exposure group. The overall frequency of cells with aberrations in the matched control individuals was 1.4%. In the total control group of 304 individuals we found significant increases in aberrations associated with smoking and with increasing age. We have also reported previously an association between sister-chromatid exchange (SCE) frequency and ETO exposure (Stolley et al., 1984). When aberration frequencies were compared with levels of SCEs there was only a weak overall association. The correlation was found in potentially exposed but not in control groups, and for any individual, one observation could not be used to predict the other.

Adult↗
PubMedDate not supplied

The twilight of national sovereignty.

The institution envisaged in the Moscow Declaration, refined in the Atlantic Charter, and elaborated at Dunbarton Oaks, was called 'the United Nations'. The Preamble to its Charter began with the words 'We the peoples', and Articles 3 and 4 provided that its members should be states. The underlying assumption appeared to be that the words 'nation', 'people' and 'state' were interchangeable. To challenge that assumption may appear to be playing at word games, equivalent to doing the Times crossword. But since language is the vehicle by which we formulate and communicate our thinking, words have always been invested with a power, and certainly a life, of their own. Words have legal consequences. If the word 'A' is synonymous with 'B', then all the rights and obligations pertaining to an 'A' attach to a 'B', although that may not have occurred to us when we cheerfully used that label. Perhaps even more importantly, they have psychological consequences. If we can secure acceptance that 'B' means 'A', then all the legitimacy invoked by an 'A', is assumed by a 'B'. The argument that I want to advance is that those who drafted the Charter did so on the assumption that the wellbeing and the integrity of a people, or of a nation, are equivalent to the integrity and wellbeing of the specific state to which they are attached on a one-to-one basis. I want to go on to argue that that proposition was never wholly true, and that it is becoming increasingly remote from the real world. I decided to begin by attempting definitions of the three words, but I quickly discovered that the task, if achievable, would require greater leisure, not to mention a wiser head, than is available to me. The first conclusion I reached is that all three words have eel-like qualities. When you think that you have grasped a meaning, it slips through your fingers. Not only do meanings change from generation to generation but they change contemporaneously according to the purpose of those who use them.

Global Health↗