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Biomedical subjects

D W Cooper

Publications and source records attributed to D W Cooper.

At least 109 records · Page 6Linked to original sources
PubMed1984

Transformation of the Hprt gene with DNA from spermatogenic cells. Implications for the evolution of X chromosome inactivation.

DNA-mediated transformation of hypoxanthine guanine phosphoribosyl transferase (HPRT)-deficient cells was used to assess the state of the chromosome Hprt gene in spermatogenic cells. It had been shown previously that DNA from the inactive X chromosome of somatic cells functions poorly or not at all in HPRT transformation, indicating that DNA modification is involved in somatic cell X chromosome inactivation (XCI). In contrast, DNA from mature sperm does function in HPRT transformation suggesting that DNA modification may not be the basis of XCI in mature sperm. In this paper, transformation of HPRT- mouse and hamster cells has been performed to test the nature of XCI during earlier stages of spermatogenesis. DNA from these developing murine germ cells was shown to be capable of HPRT transformation, extending the observation that XCI in sperm does not appear to involve a DNA modification. We also show here that DNA from mature sperm of marsupials functions in HPRT transformation, a result consistent with a role for sperm XCI in the evolution of somatic X inactivation.

Animals↗
PubMed1984

Immunology of pouch young marsupials. I. Levels of immunoglobulin transferrin and albumin in the blood and milk of euros and wallaroos (hill kangaroos: Macropus robustus, marsupialia).

The concentration of total protein, albumin, transferrin, and immunoglobulin G of adult serum, pouch young serum, milk whey and colostrum has been estimated in three species of kangaroos, Macropus robustus, Macropus rufus (= Megaleia rufa) and Macropus giganteus. No study of this kind has previously been published for any marsupial species. The three individual proteins were antigenically identical in all four kinds of fluid. Colostrum and milk whey are relatively enriched in transferrin but have low levels of immunoglobulin G. Serum concentrations of total protein, albumin and transferrin rise steadily throughout pouch life and attain adult values when the young finally leaves the pouch. Serum concentrations of immunoglobulin G are very low for the first 90-100 days of pouch life, being approximately half of those in milk whey for this period. After this the level rises rapidly and also reaches adult values when the young leaves the pouch. We suggest that in the first 90-100 days the pouch young is largely protected humorally by passive immunity acquired from the mother, and after this it increasingly makes its own responses.

Age Factors↗
PubMed1983

Studies on metatherian sex chromosomes. XII. Sex-linked inheritance and probable paternal X-inactivation of alpha-galactosidase A in Australian marsupials.

An investigation of genetic variation in the electrophoretic mobility of the enzyme alpha-galactosidase A (EC 3.2.1.22) has been carried out for 33 species of Australian metatherian (marsupial) mammals. The results are compatible with the enzyme being sex-linked in macropodids (kangaroos and wallabies) and probably in dasyurids (marsupial 'mice', etc.), as it is in eutherian (placental) mammals. The results also suggest that the mode of dosage compensation for this locus is the same as for other sex-linked loci in kangaroos, i.e. paternal X inactivation, rather than the random X inactivation system of eutherian mammals. The bearing of the enzyme mobility data on phylogenetic relationships among macropodid species is discussed.

Animals↗
PubMed1983

Common materials for emergency respiratory protection: leakage tests with a manikin.

In areas where respirators are not routinely used, emergencies (such as fires) may occur in which protection from airborne particles is necessary. The following readily available materials were tested on a manikin connected to a breathing simulator to determine the fraction of an approximately 2-micron diameter aerosol that would leak around the seal between the materials and the manikin's face: cotton/polyester shirt material, cotton handkerchief material, toweling (a wash cloth), a surgical mask (Johnson & Johnson Co., Model HRI 8137), and a NIOSH-approved disposable face mask (3M Corp., Model #8710). The leakage tests were done to supplement the measurements of penetration through the materials reported previously. Leakage fractions were determined by comparing the penetration of the same aerosol for the materials held to the face versus being fully taped to the face. At a breathing rate of 37 liters per minute, mean leakages for the materials ranged from 0.0 percent to 63 percent, depending on the material. Mean penetrations exclusive of leakage ranged from 0.6 percent to 39 percent. Use of nylon hosiery material ("panty hose") to hold the handkerchief material or the disposable face mask to the face was found to be very effective in preventing leakage. Such a combination could be expected to reduce leakage around the handkerchief to about 10 percent or less in practice, and around the mask to less than one percent, which suggests the adaptation and use of such an approach for industrial hygiene.

Dust↗
PubMed1983

X-chromosome inactivation and evolution in marsupials and other mammals.

Sex chromosome dosage compensation in Australian marsupials exhibits several characteristics not ordinarily manifested in eutherian mammals. They are: 1) preferential inactivation of the paternally derived X-chromosome in somatic tissues; 2) a state of partial inactivity at some paternally derived X-linked gene loci in some cells; 3) absence of dosage compensation in some cell types; 4) absence of nuclear sex dimorphism at interphase; 5) discordance between late DNA replication and gene inactivation in some cell types; 6) failure of the X-chromosome to behave as a single unit. Despite these seemingly major differences between the dosage compensation systems of Australian marsupials and eutherians, there are also many underlying similarities. We propose that the two systems arose from a common ancestral mechanism in which the X-chromosome was regulated in a piecemeal fashion, rather than as a whole. To determine more precisely the sequence and timing of evolutionary events, we have initiated an investigation of dosage compensation in American marsupials, which diverged from Australian marsupials soon after the divergence of marsupials from eutherian mammals.

Animals↗
PubMed1981

The indicence of severe pre-eclampsia amongst mothers and mothers-in-law of pre-eclamptics and controls.

In order to distinguish between a maternal, fetal or maternal and fetal genetic predisposition towards severe pre-eclampsia, the first pregnancies of 158 mothers and 160 mothers-in-law of pre-eclamptic women and of matched controls were analysed. Fourteen per cent of mothers of pre-eclamptics were found to have had severe pre-eclampsia, confirming previous suggestions that the condition "runs in families', in contrast to only a 3% incidence amongst mothers of controls. The incidence in mothers-in-law of both pre-eclamptics and controls was 4%, in full agreement with a maternal genotype hypothesis and suggesting that the fetal genotype plays, at most, only a minor role in the aetiology of severe pre-eclampsia. The data are in agreement with the hypothesis that a single recessive gene acting in the mother could be responsible for severe pre-eclampsia, but multifactorial inheritance is not ruled out. Mild pre-eclampsia showed no such familial tendency, indicating that the mild and severe forms of pre-eclampsia may represent separate pathological entities.

Female↗
PubMed1981

Failure to detect altered rosette inhibition titres in human pregnancy serum.

Six anti-lymphocyte antisera and 6 anti-lymphocyte globulin preparations were tested on serum from women in the first and second trimester of pregnancy and on appropriate sera from non-pregnant controls. There were no differences and the results do not confirm the claim that the serum of pregnant women contains a factor that will prevent human lymphocytes forming spontaneous rosettes with sheep red blood cells, and that this serum factor makes its appearance early in pregnancy.

Antilymphocyte Serum↗
PubMed1980

Somatic expression and autosomal inheritance of phosphoglycerate kinase B in kangaroos.

The PGK-B isozyme, currently known as PGK-2 in the mouse nomenclature, is the predominant PGK isozyme in mammalian sperm. In many species it is detectable only in sperm, in spermatogenic testes and in epididymides containing sperm. In this paper, we provide evidence that some kangaroo species express low PGK-B activity in somatic tissues, in addition to high activity in testes. Three kangaroo species, M. rufogriseus, M. robustus and M. giganteus, exhibit polymorphism of PGK-B. Breeding data support the hypothesis of autosomal co-dominant inheritance, as is the case in mice. Population data for the three polymorphisms are discussed. PGK-B is not detectable in somatic tissues or spermatogenic testis extracts of monotreme mammals, birds or lizards; it is probably restricted to therian mammals.

Animals↗
PubMed1979

Expression of PGK-A in the Australian brush-tailed possum, Trichosurus vulpecula (Kerr), consistent with paternal X inactivation.

An extensive survey of erythrocytes of marsupials other than kangaroos for electrophoretic variation if X-linked enzymes revealed two rare PGK-A phenotypes in the phalangerid Trichosurus vupecula and one in Trichosurus caninus. Four putatively heterozygous females expressed only the variant allelic isozyme in some tissues but expressed a trace of the normal isozyme in others. A putatively hemizygous male expressed only the variant isozyme in all tissues. The phenotypic patterns were consistent with those observed in kangaroos known to exhibit partial or complete parternal X inactivation in cells of females. Tow of the T. vulpecula were a mother and her female pouch young, further suggesting that paternal X inactivation occurs in T. vulpecula. This peculiar mechanism of dosage compensation may not be restricted to kangaroos.

Animals↗
PubMed1979

Marsupial--mouse cell hybrids containing fragments of the marsupial X chromosome.

Hybrids were obtained from fusions of HPRT-deficient mouse fibroblasts and marsupial lymphocytes. These hybrids retained no identifiable marsupial chromosomes, but all expressed the marsupial form of HPRT. Half the clones also expressed marsupial PGK-A, and half of these also marsupial G6PD; no other marsupial allozyme markers were detected. Since G6PD is known to be sex linked in these species, we conclude that Hpt and Pgk-A are also located on the X chromosome and the markers lie in the order Hpt-Pgk-A-Gpd.

Animals↗
PubMed1979

A critique of the U.S. standard for industrial exposure to sodium hydroxide aerosols.

Published studies of the toxicity of sodium hydroxide aerosols are few. These studies were generally marred by inadequate characterization of particle size and chemical compositon and of the ambient humidity. Because NaOH aerosols can readily undergo reaction with carbon dioxide to form sodium carbonate, a much less alkaline (and less hygroscopic) compound, these shortcomings may warrant a reconsideration of the NaOH standard and the consideration of a Na2CO3 standard.

Aerosols↗
PubMed1979

Genetic control of severe pre-eclampsia.

A genetic analysis has been made of published and new data on the familial occurrence of severe pre-eclampsia in primigravid women. This has shown that the condition may be largely a Mendelian recessive one. Bcause the condition occurs only in pregnancy, and because susceptible women cannot otherwise be identified, it is difficult to decide whether the genotype of the parent or of the offspring carried in utero leads to the condition. Data on the incidence of severe pre-eclampsia in the relatives of women who have suffered eclampsia support the maternal genotype hypothesis, while similar data, in which the index cases were women who had had severe pre-eclampsia, are more compatible with the fetal genotype hypothesis. Data on the incidence of the condition in blood relatives of index cases compared to the incidence in their corresponding in-laws are now required. Such a comparison would allow a choice to be made between the two hypotheses if one or the other were correct, or would assess the contribution of each if a genotype X genotype interaction were involved. Recurrent severe pre-eclampsia seems to have the same genetic basis as the more common primigravid type. However, mild, that is non-proteinuric, pre-eclampsia usually seems to be inherited independently of the severe form.

Female↗
PubMed1978

Autosomal inheritance of phosphoglycerate kinase in the domestic chicken (Gallus domesticus).

Electrophoretic variants of the glycolytic enzyme phosphoglycerate kinase (PGK) in the domestic chicken, Gallus domesticus, were found to be inherited in an autosomal manner. No sperm-specific isozyme of PGK exists in the chicken. This is in direct contrast to previous results from therian (placental and marsupial) mammals in which there are two isozymes of PGK, an autosomal form largely or wholly confined to sperm and a sex-linked form found in most other tissues. The implications of these and other results for the question of homology between the avian Z chromosome and the mammalian X chromosome are discussed. It is concluded that there is no evidence of homology between the X chromosome and the Z chromosome.

Animals↗
PubMed1978

Fiber counting: a source of error corrected.

Optical counting of fibers (from a filter sample of industrial air, for example) involves determining how many fibers are within counting fields which are squares of side lengths. It is correct to count all those fibers which are completely within the field and half of those which intersect only one side. It is shown here to be incorrect to count half those fibers which intersect two sides; the magnitude of this error is calculated, the calculations being verified through a Monte Carlo simulation. The fractional overcount for fibers of length L less than or equal to s is (L/s)2/2pi.

Air Pollutants↗