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Biomedical subjects

A E Freeman

Publications and source records attributed to A E Freeman.

At least 91 records · Page 5Linked to original sources
PubMed1981

Postpartum distribution of costs and disorders of health.

More than 17,000 events from 1,305 lactations of 551 cows in two herds were analyzed to quantify the distribution of costs and disorders of health during a lactation. Categories were mammary, reproduction, locomotion, digestion, respiration, other, insemination, and total. The largest costs and most disorders were associated with initiation of lactation rather than period of peak daily milk yield. Mammary and reproductive costs were 71% of total health cost in the first 30 days postpartum. Mammary and reproductive costs were 55% of the total health cost in an average 30-day interval. Insemination cost was 50% of the total health cost between 60 to 89 days postpartum. Parturition and extended days open were periods of large reproductive cost. Postpartum distributions of health cost and health disorders were similar implying that the prices assigned for severity added little information to counting disorders.

Animals↗
PubMed1981

Age of dam and maternal effects for dystocia in Holsteins.

Genetic correlations between dystocia in first with later parities and between direct with maternal effects for dystocia were estimated. Dystocia in first and later parities represent similar traits because of a large genetic correlation of .84. This similarity should allow calving reports on older dams and heifers to be combined in predicting a bull's calving performance. Correlations for direct with maternal effects were -.38 for the heifer population and -.25 for the cow (second and greater parities) population. This correlation would reduce progress from selecting for reduced dystocia if only direct effects were considered. Breeding programs to reduce dystocia should consider both direct and maternal performance.

Age Factors↗
PubMed1981

Genetic aspects of lactation curves.

Parameters of lactation curves were defined by a gamma-type function for 113,705 lactations from the California Dairy Herd Improvement Association. Heritabilities and genetic correlations were estimated from a mixed-model analysis of paternal half sisters for first, second, third, and later lactations. Daily milk production on day 6 postpartum was estimated from production at first test-day to reduce the percentage of atypical lactations to less than 1% instead of an expectation of 30% without estimating production for day 6. The natural logarithm of the gamma-type function was ln(yt) = ln(a) + b ln(t) - ct, where yt was daily milk production in the tth week and ln(a), b, and c were coefficients. Persistency (c-(b+1)), week of peak yield (b/c), peak yield (a(b/c)be-b), and coefficient of determination were estimated from coefficients for each lactation. Heritabilities in first lactation were: ln(a) . 10 +/- .01, b .06 +/- .01, c .14 +/- .02, persistency .02 +/- .01, week of peak yield .02 +/- .01, peak yield .23 +/- .02, and determination .03 +/- .01. Heritabilities for later lactations were similar. Cows in first lactation had lower ln(a), lower peak yield, lower c, greater persistency, and took longer to reach peak yield than did cows in later lactations. Genetic and phenotypic correlations indicated that selection for increased peak yield would be associated with increased ln(a), b, and c without changing persistency or week of peak yield.

Animals↗
PubMed1980

Characterization of mouse fetal lung cells cultured on a pigskin substrate.

Lung organ bits taken from full-term mice were explanted on the dermal surface of sterile, dead pigskin. The cells migrated onto the pigskin dermis and proliferated to form an organoid culture consisting of ductular structures separated by a matrix of epithelial cells. Cells within the ductular structures were ciliated, produced mucin, and exhibited the activities of nonspecific esterase and gamma-glutamyl transferase; therefore they were considered to be derived from bronchial epithelium. Cells forming the matrix possessed the activities of nonspecific esterase and alkaline phosphatase and contained lamellar structures typical of surfactant-producing pneumocyte Type II cells; therefore they were considered to be derived from alveolar precursor cells.

Alkaline Phosphatase↗
PubMed1980

Fine structural identification of organoid mouse lung cells cultured on a pigskin substrate.

Mouse full-term embryonic lung tissue was cultured as organ bits using dead, sterile pigskin dermal collagen as a substrate. Explanted organ bits grew on the surface of, and into, the pigskin dermal collagen for at least 9 weeks after the initiation of culture. The outgrowth consisted of a thick cellular sheet containing various sizes of ductular structures within a cellular matrix that did not show any particular structure. Electron microscopic observation revealed that the larger ductular structures consisted largely of ciliated cells. The smaller ductular structure consisted largely of Type II pneumocytes containing lamellar bodies. The cellular matrix consisted of Type II pneumonocytes and other cell types including fibroblasts and macrophages in the early stage of cultivation. Macrophages invaded the pigskin dermal collagen. An intermediate cell type, which has never been observed in vivo, possessing both cilia and lamellar bodies was identified in the larger ductular structures. Upon comparison of the ultrastructure of the organoid in vitro cultures in pigskin with the original fetal lung, it was apparent that cytodifferentiation had occurred. The organoid components and structure of the cultured cells more closely resembled adult lung than the fetal lung used to initiate the cultures.

Animals↗
PubMed1980

Relationship of dystocia transmitting ability with type and production transmitting ability in Holstein bulls.

Relationships of transmitting ability for dystocia with transmitting abilities for type and production in Holstein bulls were estimated. Genetic correlations between dystocia transmitting ability with Predicted Difference (PD) were: milk .00, fat .00, test -.02, and dollars .00. Genetic correlations for transmitting ability of dystocia were -.28 with Predicted Difference Type and -.23 with Type Production Index. Correlation indicated improved conformation will increase dystocia. The relationship of transmitting abilities from Mating Appraisal for Profit with dystocia indicated that scale (size) has a major effect on the type-dystocia relationship. Large size results in both high type classification and increased dystocia. Correlations of rump and center support with dystocia were also in excess of .20.

Animals↗
PubMed1978

In vitro and in vivo indications of the carcinogenicity and toxicity of food dyes.

Eight food dyes or commercial color mixtures certified for use in the United States were tested for their ability to transform in vitro a serial line of Fischer rat embryo cells previously reported to be a sensitive indicator of chemicals having carcinogenic potential. Malignant cell transformation was induced by a commercial mixture (G2024) of two of these dyes (Blue 1 and Yellow 5) and by Blue 2, Green 3 (one of two experiments) and Red 4. Food dyes Blue 1, Red 3, Yellow 5 and Yellow 6 did not induce cell transformation. One to 1.5 mg of each dye was injected into suckling LVG or Graffi hamsters which were monitored for tumor induction and/or death over a 330-day period. None of the non-transforming dyes (Blue 1, Red 3, Yellow 5, Yellow 6) or Green 3 induced a significant increase in tumor (mostly lymphoma) incidence or animal mortality. Three of the transforming dyes (Blue 2, Green 2024, Red 4) did increase tumor incidence and/or mortality in at least one strain of hamster. We conclude the the in vitro assay suggested that certain food dyes were carcinogens and that in vivo studies in hamsters supported this interpretation.

Animals↗
PubMed1977

Heteroploid conversion of human skin cells by methylcholanthrene.

Cultured epithelial cells from human skin generally had 3- to 30-fold more hydrocarbon-metabolizing activity than fibroblasts from skin of the same donor. This activity was constant for up to 55 days in primary culture but was lost rapidly upon physical subdivision of the cultures. Treatment of primary mixed fibroblasts and epithelial cell cultures with methylcholanthrene, but not phenanthrene, led to development of actively growing fibroblastic cultures with many heteroploid cells. Unique marker chromosomes, stable over a number of cell population doublings, were identified in several of the heteroploid cell strains. Pure cultures of fibroblasts from the same donors did not undergo heteroploid conversion in response to methylcholanthrene. Spontaneously occurring heteroploidy in logarithmic phase human fibroblasts is a rare event; thus, heteroploid conversion may be a useful marker for chemical transformation of human cells. Because methylcholanthrene seems to have little transforming effect on human skin fibroblasts, human skin epithelial cells, because of their hydrocarbon-metabolizing activity, may serve to convert methylcholanthrene from a distal to an ultimate carcinogenic form.

Adolescent↗
PubMed1976

Growth and characterization of human skin epithelial cell cultures.

In 129 of 140 attempts, human skin cells were successfully cultured on the dermal collagen bed of sterile, dead pigskin. Diploid epithelial cells grew selectively on the collagen bed; fibroblasts grew on the glass surfaces of the culture dishes. The cultures could be subdivided physically up to six times at a 1:2 split ratio, but at least 24 to 48 cell generations were produced over the months the cells could be carried. Much of the cell multiplication resulted in maturation into distinct basal, squamous, granular, and keratinized cell layers. The cultured cells were considered epithelial because of their shape, possession of intercellular bridges, desmosomes and tonofibrils, and because they formed maturating epithelium in vitro and upon transplantation back to the original human donor. As the cells grew they digested the pigskin collagen, thus producing clear zones that could be used to monitor and quantitate cell growth. Multiplication of epilthelial cells, rather than migration, was indicated by mitotic figures in colchicine-treated cultures and by DNA synthesis.

Cell Division↗
PubMed1976

Prevention of viral-chemical co-carcinogenesis in vitro by type-specific anti-viral antibody.

Low passage Fischer rat embryo cultures, which are normally very resistant to transformation by 3-methylcholanthrene but are highly susceptible when chronically infected with the Rauscher murine leukemia virus, were completely protected from transformation by methylcholanthrene when treated with neutralizing antibody specific for the leukemia virus prior to and during treatment with methylcholanthrene. Sister cultures were not protected by neutralizing antibody specific for the B-tropic radiation leukemia virus. This demonstrates clearly a definite type specific role for Rauscher murine leukemia virus in the 2-methylcholanthrene transformation system in rat cells.

Antibodies, Viral↗
PubMed1976

Acceleration of transformation of rat embryo cells by rat type C virus.

Sprague-Dawley and Fischer rat embryo cells became spontaneously transformed about 20 passages after release of endogenous ecotropic type C virus (SD-RaLV and F-RaLV). The virus-producing transformed cells showed loss of contact inhibition, increased growth rate, and tumorigenicity in vivo. Exogenous infection of other Fischer rat embryo cultures in early passage with SD-RaLV and F-RaLV markedly accelerated their rates of transformation.

Animals↗
PubMed1975

Type-C virus-specific nucleic acid sequences in cultured rat cells.

Single-stranded DNA transcripts of rat type-C viruses prepared in the presence of actinomycin D, hybridized specifically to DNA of several rat cell cultures with no obvious qualitative or quantitative differences. Similar products prepared from a pseudo-type sarcoma virus with contributions from rat and mouse type-C viruses hybridized to both rat and mouse cellular DNA, while mouse viral transcripts did not hybridize to rat cell DNA. Viral RNA was detected in all rat cells by means of the rat viral DNA transcripts, with some differences between untreated low-passage cells and sister cultures treated with bromodeoxyuridine or bromodeoxyuridine and methylcholanthrene. Cells treated with both compounds were previously shown to be transformed and turorigenic, and these were distinguishable by kinetic analysis from the control cells.

Amino Acid Sequence↗
PubMed1975

Uptake, metabolism, and persistence of 3-methylcholanthrene in rat embryo cells infected with murine leukemia virus.

The uptake and persistence of 3-methylcholanthrene have been followed in both unifected rat embryo tissue culture cells and in cells infected with type C RNA virus. No significant differences in these parameters were observed as a function of viral infection or cell passage level. Moreover, neither binding of 3-methylcholanthrene to nucleic acids or proteins nor carcinogen metabolism were altered by the viral carrier state. Although transformation of rat cells by chemical carcinogens alone has been reported by us and other authors, the low-passage rat embryo cells used in this study will not transform unless cells are carrying exogenous type C RNA virus. We thus suggest that the virus must play a more direct role in the transformation process rather than affecting the ability of the cell to absorb, retain, or metabolize the chemical.

Animals↗