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Biomedical subjects

A E Freeman

Publications and source records attributed to A E Freeman.

At least 73 records · Page 4Linked to original sources

In vivo-like growth of human tumors in vitro.

We show that diverse human tumors obtained directly from surgery or biopsy can grow at high frequency in vitro for long periods of time and still maintain many of their in vivo properties. The in vivo properties maintained in vitro include three-dimensional growth; maintenance of tissue organization and structure, including changes associated with oncogenic transformation; retention of differentiated function; tumorigenicity; and the growth of multiple types of cells from a single tumor.

Animals↗

Myxoid chondrosarcoma with a translocation involving chromosomes 9 and 22.

Myxoid chondrosarcoma is an uncommon neoplasm thought to be derived from mesenchymal chondrocytic cells. Although cytogenetic abnormalities have been reported in sarcomas, too few cases have been studied to determine the frequency of nonrandom chromosomal changes in mesenchymal tumors. In this article, we describe a chondrosarcoma with a nonrandom reciprocal translocation t(9;22)(q22;q11). The cellular homologue to the retrovirus transforming gene of simian sarcoma virus is located on chromosome #22, and its possible significance in this case is discussed.

Chondrosarcoma↗

Potential genetic gains from producing bulls with only sires as parents.

Micromanipulation of sperm and ova has been suggested as a means to produce progeny of two sires instead of a sire and dam. Selection schemes taking advantage of this technology could produce genetic gains 1.5 to 2 times current gains. An optimum strategy both genetically and economically would be to breed 99% of the population to young sires and 1% to progeny-tested sires. The genetic pathway from sires to sons could become the only pathway affecting genetic gain; this would eliminate problems of cow evaluation and would give artificial insemination organizations more control over quality of young sires. Inbreeding would not be a problem, and few other technologies could offer superior rates of genetic gain.

Animals↗

Secondary traits: sire evaluation and the reproductive complex.

Genetic aspects of dystocia, reproduction and its association with production, and calf livability are reviewed. Measures of each are presented. Genetic and maternal effects, sire evaluation by births from heifers and older cows, and correlations with production and type are discussed for dystocia. Heritabilities for measures of reproduction were low. Fertility and production were antagonistic in cows but complementary between heifer breedings and production in first lactation. There were differences among sires for calf mortality up to 48 h after birth, but heritabilities were low. Livability and dystocia are closely correlated genetically. Methods for multiple traits ideally should be used for sire evaluation.

Animals↗

Cell transformation by chemical agents--a review and analysis of the literature. A report of the U.S. Environmental Protection Agency Gene-Tox Program.

The literature on cell transformation by chemical carcinogens has been critically reviewed. This subject is highly relevant to carcinogenesis in vivo, because the phenotypic changes that are collectively referred to as cell transformation usually involve the acquisition of tumorigenicity on inoculation into suitable rodent hosts. The systems chosen for review fall into 3 categories: cell strains (cells with a limited lifespan); cell lines (cells with an unlimited lifespan); and oncogenic viral-chemical interactions involving cells (Fischer rat embryo cells expressing an endogenous retrovirus, mouse embryo cells expressing the AKR leukemia virus, chemical enhancement of a simian adenovirus, SA7 transformation of Syrian hamster or rat embryo cells). Of the entire literature reviewed, 117 papers have been accepted for data abstraction by pre-defined criteria; these include 41 references to cell strains, 40 in cell lines, and 38 in viral-chemical interactions including cells. Because different systems have been reviewed, it would be meaningless to group all the compounds. The overall summary of the systems is as follows (many compounds have been tested in more than one system and, hence, are duplicated in these totals). (Chart: see text) In general, there is a reasonably good correlation between the results of the cell transformation systems and in vivo carcinogenesis. However, the many deficiencies of the EPA Merged Carcinogen List preclude definitive comparisons. Moreover, a number of 'false negatives' were obtained in systems that did not employ external metabolic activation. Further validation of all systems is required, but it seems very probable that several cell transformation systems will become valuable in assaying (with reasonable time and cost) the carcinogenic potential of environmental chemicals.

Animals↗

Effects of laminin, fibronectin and type IV collagen on liver cell cultures.

The effects on mouse liver cells of laminin, fibronectin and type IV collagen, all of which are the main matrix of the basement membrane, were studied. Laminin, a glycoprotein isolated from cultures of rat yolk sac carcinoma cells, promoted the attachment of mouse fetal liver cells to laminin-coated dishes, but did not have a strong influence upon the attachment of normal adult liver cells. On the other hand, fibronectin which was purified from mouse plasma promoted the attachment of adult liver cells but not that of fetal liver cells. The number of neonatal liver cells attached to the surfaces coated was intermediate between those of fetal and adult liver cells in each matrix. DNA synthesis and cell proliferation during the culture of full-term fetal liver cells in laminin-coated dishes were higher than those in fibronectin- or type IV collagen-coated dishes. The amount of alpha-fetoprotein secreted in the laminin-coated dishes was more than in other groups. No differences in secretion of albumin into media, however, were observed in either group. These results suggest that laminin may be necessary for cell growth, tissue organization and cell differentiation during the normal development of liver in vivo.

Albumins↗

Modulation of fetal mouse liver cells cultured on a pigskin substrate.

Mouse fetal liver cells cultured on a pigskin epidermal substrate grew for 7 weeks. Different enzymes and proteins, i.e. gamma-glutamyl transferase (GGT), nonspecific esterase (NE), lactic dehydrogenase (LDH), alpha-fetoprotein (AFP), and albumin were studied histochemically and/or biochemically. The activity of GGT was high at the beginning of culture and then decreased rapidly. The activities of NE and LDH were high during the culture. Release into the media and localization of AFP suggested active synthesis during the early stages. AFP levels gradually decreased and could be demonstrated only in trace amounts after 3-4 weeks of culture. On the other hand, the production of albumin was weakly evident early and became more and more evident after the second week in culture. Hydrocortisone modulated AFP and albumin production. The effect of hydrocortisone was to prolong expression of AFP and to reduce expression of albumin. Electron microscopic observations showed that the cultures consisted of organelle-rich parenchymal cells associated with the pigskin basement membrane by pseudopod-like structures. These results indicate that fetal mouse parenchymal cells were cultured and modulated on a pigskin epidermal substrate.

Albumins↗

Variances, repeatabilities, and age adjustments of yield and fertility in dairy cattle.

Breeding receipts from artificial insemination were matched with records of milk yield from northeastern United States. Nine measures of yield and 10 measures of fertility were investigated. A completely random model with herd-year-season, sire, and interaction of sire by herd-year-season was applied by parity; interaction of sire by herd-year-season was not important except possibly for fertility of virgin heifers. Sires accounted for 6 to 7% of yield variation and herd-year-seasons accounted for about 45%. Measures of fertility had small sire variances, and herd-year-season variance was much smaller than for yield. Effects of age within parity were significant for yield from ordinary least-squares analysis. Age adjustment factors were obtained for measures of yield. Repeatabilities of first- and second-parity yield ranged from .40 to .61 whereas repeatabilities of fertility were .03 to .13. Repeatabilities of virgin heifer and first-parity fertility were .01 to .03, suggesting heifer and cow fertility may not be related.

Age Factors↗

Yield and fertility relationships in dairy cattle.

Measures of yield and fertility were obtained from breeding receipts of artificial insemination and records of test-day yield. Estimates of heritability were by Henderson Method 3, maximum likelihood, and restricted maximum likelihood. Heritabilities for measures of yield varied, but most were within the range of earlier estimates. Measures of fertility had heritabilities from 0 to .03. Alternative upper bounds were placed on days open, number of services, and service period, and always the measure with the lesser bound had higher heritability for first parity. Measures of yield for early stages of lactation had slight positive phenotypic correlations with fertility whereas those for measures of cumulative yield later in lactation increased in relation to effect of gestation. Genetic correlations of first-parity yield and most measures of fertility were positive and less influenced by stage of lactation than phenotypic correlations. Antagonism moderated for second parity. Most genetic correlations were not significantly different from zero for third parity. Considerable genetic antagonism of yield and fertility may be of limited consequence because estimates of genetic variance of fertility were near zero.

Animals↗

Association of heifer fertility with cow fertility and yield in dairy cattle.

Genetic correlations of heifer fertility and first-parity yield usually were negative and opposite in sign from genetic correlations of first-parity fertility and yield. Most estimates of genetic correlation between heifer and first-parity fertility were not significantly different from zero. Increasing yield may improve genetic potential for fertility, but stress of increased yield may overcome genetic potential for improved fertility. Days open and 305-day yield for first parity were considered with index selection; sires were evaluated on daughter performance. Days open had a small influence on the selection index; genetic gains in days open for first parity were largely offset by correlated losses in service period for heifers. Restricted index selection, holding days open constant, required considerable economic importance of days open.

Animals↗

Genetic relationship between calf livability and calving difficulty of Holsteins.

Multitrait procedure was used to investigate the genetic relationship between calf livability and calving difficulty of Holsteins. The genetic correlation between calf livability and calving difficulty was .66. Heritabilities were .9% for calf livability and 4.1% for calving difficulty. The product-moment correlation (.4) between sires' transmitting abilities estimated separately for livability and dystocia, with properties of Best Linear Unbiased Predicator, underestimated the genetic correlation (.66). The correlated response of calf livability is expected to be 41% greater when selection is for dystocia than is expected from direct selection on calf livability.

Animals↗

Factors affecting calf livability for Holsteins.

A total of 136,775 records from Holstein calvings was obtained from the National Association of Animal Breeders. Calf mortality (scored as dead at birth plus dead by 48 h) was greater for males (7.6%) than for females (5.6%). First parities of dams showed about two times as much calf mortality as later parities (10.5 versus 5.6%). Relationship was nonlinear between calf livability and size of calf, regardless of parity-of-dam and sex-of-calf effects. Dead calves averaged 1.2 days shorter gestation than live calves (279.6 days). Sex of calf, parity of dam, and linear and quadratic gestation length affected calf livability when the model also included sires. Percentage of calf mortality of progeny of individual sires ranged from 1 to 16% for sires with at least 60 progeny. Mixed model estimates of heritabilities of livability were 1.02% (when coded as 1-alive at 48 h, 2-dead at birth, and 3-dead within 48 h) and 1.54% (when coded as 1-alive, 2-dead by 48 h). Heritability decreased 26% when gestation length was ignored. Attempts to normalize scores did not improve estimates of heritability. Heritability for livability was small.

Animals↗

Effects of basement membrane matrix on the culture of fetal mouse hepatocytes.

The effects of laminin, fibronectin and type IV collagen, all of which are major matrix components of the basement membrane, upon fetal mouse hepatocyte culture were studied. Among these matrices, laminin showed the greatest effect on DNA synthesis, cell proliferation, the secretion of alpha-fetoprotein and cell attachment. The effects of fibronectin and type IV collagen were slight with regard to the promotion of growth and cell attachment. However, there were no differences in the secretion of albumin into the media among the groups. These results suggest that laminin may be necessary for the cellular growth and functional maintenance of immature liver cells during normal development of the liver in vivo.

Animals↗

Duct, exocrine, and endocrine components of cultured fetal mouse pancreas.

Twenty to twenty-two days postcoitum mouse fetal pancreas organ bits were cultured on the dermal surface of irradiated pigskin as a substrate. The medium used for long term culture consisted of Eagle's Minimum Essential Medium with the addition of 10% bovine serum, 0.02 U/ml insulin, 0.025 microgram/ml glucagon, 3.63 microgram/ml hydrocortisone, 100 microgram/ml soybean trypsin inhibitor or 10(-8) M atropine. When the medium lacked trypsin inhibitor or atropine but contained the three hormones, the pigskin support began to be destroyed after 2 to 4 wk in culture. Thereafter, the cultured cells could not grow and survive on the digested pigskin. When 10(-6) M atropine was added to the medium, amylase secretion from cultured cells and destruction of pigskin were inhibited completely but pancreas cells could not grow or survive. In contrast, 100 microgram/ml soybean trypsin inhibitor or 10(-8) M atropine permitted cell growth, permitted amylase secretion from the cultured acinar cells, and prevented the destruction of pigskin. Under these conditions pancreas cells migrated or grew or both from the organ bits onto the surface of the pigskin dermis and organoid aggregations formed. Hydrocortisone was needed to permit growth for more than 2 wk. Glucagon and insulin had additive effects. Light and electron microscopic observations indicated the culture of at least five kinds of cells, i.e., duct, acinar, centroacinar, endocrine, and mesenchymal. The majority of cultured cells were duct cells and acinar cells. There were few mesenchymal cells. Mouse pancreas cells were cultured for at least 12 wk by this method.

Amylases↗

Projecting health cost from research herds.

Health costs by categories were summarized from 1,999 lactations of 863 cows in three dairy herds. These costs were projected to Dairy Herd Improvement data. Health categories were mammary, reproduction, locomotion, digestion, respiration, other, and total. The largest estimated total health cost of $67.63 was associated with postpartum length (days in milk and dry) greater than 420 days, an average 98 days dry, and milk production greater than 8,250 kg in fourth or later terminal lactations. The smallest estimated total health cost of $22.25 per lactation was associated with production between 5,750 and 6,999 kg in the nonterminal first lactation with postpartum length less than 300 days. For nonterminal first lactations of intermediate length, the estimated total health cost represented 3 to 6% of the value of milk production. First-calf heifers with milk production less than 5,750 kg and postpartum length 300 to 419 days had the least mammary cost. Cows in their fourth or later lactations with postpartum length greater than 420 days and milk production less than 5,750 kg had the highest reproductive cost. Mammary cost increased and reproductive cost decreased with increased days dry. Cows in terminal lactations had $11.38 more total health cost, $4.33 more mammary cost, and $6.31 more reproductive cost than cows in complete nonterminal lactations. Relatively more reproductive than mammary cost occurred in terminal lactations compared to nonterminal lactations. Mammary cost remained the largest component of total health cost. Multiparous cows had more total health, mammary, and reproductive costs than first parity cows. The repeatibility of total health cost was .12 +2- .03.

Animals↗

Factors affecting milk yield and reproductive performance.

Dairy Herd Improvement testing records of 201 dairy herds of sizes from under 100 to over 1000 cows and herd average milk yields from under 5,000 to over 10,000 kg were studied. Average days to first postpartum breeding tended to be less in herds of over 500 cows. Herds of 300 to 600 cows had highest production per cow. Herds with higher average yields averaged shorter intervals to first postpartum breeding and fewer days open. Days open included farrow cows arbitrarily assigned 305 days open. Number of breedings changed little as herd yield increased, but days open for highest producing herds averaged one estrous period shorter than for low producing herds, suggesting better detection of estrus. For the individual cow, high yield or associated factors have a small but real antagonistic association with reproductive efficiency. Days to first breeding, to last breeding, and days open increased .27, .80, and .61, and number of breedings increased .014 for each 100 kg increase in 180-day yield of fat-corrected milk. The record averages of high-producing herds indicate this antagonism may be overshawdowed by good management; effective estrus detection probably is a major factor.

Animal Husbandry↗

Environmental and physiological factors affecting mastitis at drying off and postcalving.

Duplicate milk samples from udder quarters were collected from 3987 cows when the cows were dried off and again postcalving. Samples were cultured for staphylococcal, Streptococci agalactiae, other streptococci species, and coliform organisms. Cows were treated with one of five dry cow therapy drugs or left as untreated controls after collection of samples at dry off. Cows treated with dry cow therapy drugs had more quarters cured during the dry period than did untreated control cows for all organisms considered. A program of dry cow treatment plus teat dipping was superior to dry cow treatment only, teat dipping only, or neither. Cows were more vulnerable to mastitis infections with increasing age. Month of year of drying off affected mastitis infection, although trends were erratic and varied by organism. Mastitis infections at dry off under different herd management systems of type of milking equipment, type of milking facility, and type of housing were dependent on the organism. Management systems had little influence on mastitis infections postcalving. Higher producing cows had fewer mastitis infections when dried off, but milk production the previous lactation had little influence on mastitis infections postcalving.

Age Factors↗

Differentiation of fetal liver cells in vitro.

Fetal mouse liver hepatocytes proliferate on a substrate of irradiated pigskin epidermis scored with scalpel blade slits to permit cell access to the basement membrane. At the time the cells are explanted, fetal genes, such as those responsible for production of alpha-fetoprotein (AFP) and gamma-glutamyltransferase (GGTase), are strongly expressed. The levels of GGTase decrease rapidly and become undetectable within 2 weeks. The levels of AFP decrease more gradually but become undetectable after 3-5 weeks in culture. As the AFP levels decrease, there is a concomitant increase in albumin production. Hydrocortisone prolongs production of AFP (for up to 8 weeks) but not of GGTase, and it decreases albumin production for up to 8 weeks. Once cells lose AFP expression, addition of hydrocortisone does not restart it. Based on these data, fetal mouse liver hepatocytes, cultured on pigskin, seem to be an excellent in vitro model for liver cell maturation.

Animals↗