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J N Anderson

Publications and source records attributed to J N Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1983

Nuclease sensitivity and DNA methylation in estrogen regulation of Xenopus laevis vitellogenin gene expression.

Estrogen activates transcription of the vitellogenin genes in livers of male Xenopus laevis. We have examined the conformation of the vitellogenin genes in chromatin and the methylation state of one vitellogenin gene during the process of estrogen stimulation and withdrawal. Sensitivity of the vitellogenin genes to DNase I digestion parallels transcription. The vitellogenin genes are insensitive to DNase I digestion in unstimulated liver cells, become more sensitive to DNase I digestion following estrogen activation of vitellogenin gene transcription, and are insensitive to DNase I digestion in liver cells withdrawn from estrogen. In contrast, the methylation state of nine potential methylation sites within the vitellogenin A1 gene is identical in red blood cells, unstimulated and withdrawn liver, estrogen-stimulated liver, and hepatocytes purified from estrogen-stimulated liver. Rapid transcription of the vitellogenin genes in estrogen-stimulated liver cells occurs with six of the nine methylation sites examined fully methylated.

Animals↗
PubMed1983

Monoclonal antibodies to tissue-specific chromatin proteins.

Antisera raised in mice to chromatins from different tissues of the chicken reacted preferentially with the chromatin type that was used for immunization. This tissue specificity was also evident in the spectrum of monoclonal antibodies generated when mice were immunized with erythrocyte chromatin. Three erythroid-specific antigens and one antigen that was present in a number of chicken tissues were characterized in further detail. These antigens, which comprised less than 0.1% of the erythrocyte chromatin proteins, were nuclear localized although three were also detected in the cytoplasm. Two of the erythroid-specific antigens existed as multiple polypeptides in isolated chromatin. The multiple chromatin forms of one antigen were derived from a precursor protein that was selectively cleaved within 1 min after erythrocyte lysis. Analysis of this antigen in extracts from erythrocytes and reticulocytes indicated that the cleavage of the precursor protein was developmentally regulated in vivo.

Animals↗
PubMed1983

Health and illness in Pilipino immigrants.

Immigrants from the Philippines and their descendants have tripled in number in the United States in the past 18 years. They will soon surpass 1 million and will be the largest Asian-American minority. Pilipinos in the United States are diverse ethnolinguistically and in important socioeconomic and demographic dimensions, one notable feature being the high level of education and professional status of many recent immigrants. Nevertheless, the health and disease circumstances of Pilipinos and their views of health and illness have been surprisingly neglected to date. A generic principle fundamental to their view of health is that concerning the maintenance of balance. Proper social and cultural conduct is believed to help avoid health problems. Imbalances in social relations, infringements of cultural norms or adverse interaction with the supernatural are linked, in the cultural logic of Pilipinos, to illness.

Asian↗
PubMed1982

Hormonal regulation of the conformation of the ovalbumin gene in chick oviduct chromatin.

We have examined the effects of steroid hormones in the chromatin sensitivity of the ovalbumin gene to micrococcal nuclease and have attempted to define the importance of the nucleosome core, higher order chromatin folding, and transcription in the maintenance of the nuclease-sensitive conformation of the ovalbumin chromatin. Solution hybridization studies demonstrated that the sensitivity of the ovalbumin gene in oviduct nuclei to micrococcal nuclease paralleled the hormone-dependent transcription of the ovalbumin gene in the immature chick. Blot hybridization analysis also revealed a hormone-dependent change in this chromatin region since ovalbumin DNA fragments from nuclease-treated hen and estrogen-stimulated chick oviduct nuclei exhibited nucleosomal repeat patterns that were less discrete than those observed for the ovalbumin specific fragments from liver and hormone-withdrawn oviducts. This transcription-related conformation was not the result of enhanced sensitivity of the ovalbumin-containing nucleosomal cores since the bulk of the nucleosomes associated with the ovalbumin chromatin were not preferentially cleaved internally by micrococcal nuclease. Rather, an analysis of the fragmentation of the ovalbumin chromatin as a function of digestion extent suggested a mechanism in which the heightened sensitivity resulted from the collective expansion of the nuclease cutting sites in the linker regions of the ovalbumin chromatin because the gene was in an unfolded conformation. The transcription-specific conformation was not merely a consequence of RNA synthesis per se since the selective sensitivity of the gene was unaffected by treatment of oviduct nuclei with alpha-amanitin, actinomycin D, or RNase. In addition, the presence of the transcriptional complex on the ovalbumin chromatin was presumably not required for selective nuclease recognition since preferential cleavage was observed under conditions expected to deplete oviduct nuclei of template-bound RNA polymerase and nascent RNA chains. These results are consistent with a model in which the expressed ovalbumin gene is in an unfolded polynucleosomal structure whose formation is related to transcriptional activity but not dependent on the transcriptional process.

Animals↗
PubMed1980

The strength and fracture toughness of calcium hydroxide preparations.

The strength of a brittle material depends upon the toughness of the material itself and the degree of perfection with which it can be placed. This study shows that both the compressive and tensile strength of calcium hydroxide lining materials is dependent on the fracture toughness at unstable crack propagation, KIC, and the size, number and distribution of pores (which are the defects that nucleate fracture). Of the products tested here, Dycal possesses the greatest actual strength due to a higher than average KIC value and relatively few isolated small pores. However, the greatest potential for strength exists in Reocap which has a KIC value a factor of 2.4 greater than its nearest rival (Dycal). Unfortunately its strength, as determinedhere, is less than Dycal due to the large number of pores in close proximity to each other.

Calcium Hydroxide↗
PubMed1979

The Lyon injector.

Explore the source record for details and available documents.

Dental Casting Technique↗
PubMed1978

Fractionation and characterization of chromosomal proteins by the hydroxyapatite dissociation method.

A method was developed which enables the characterization and fractionation of chromosomal proteins according to their chromatin binding properties. The method is based on the ability of hydroxyapatite to bind native chromatin in solutions which do not dissocciate chromosomal proteins from the DNA. The proteins are then selectively dissociated from the immobilized chromatin by treatment with NaCl, urea, or guanidine HCl. The hydroxyapatite dissociation method represents a rapid one-step fractionation procedure which results in the quantitative recovery of chromosomal proteins devoid of nucleic acids and is suitable for large preparations. The hydroxyapatite dissociation method provides a versatile procedure for the study and preparation of chromosomal proteins. The patterns of dissociation of both histones and nonhistone chromosomal proteins by NaCl and urea from chicken oviduct chromatin were characterized by this method. In addition, this technique enabled the purification of the major histone species in a single operation. Partial purification of specific nonhistone proteins, including the estrogen receptor, was also achieved. We suggest that this method will be a useful tool in elucidation of the chemical and biological properties of the proteins from chromatin.

Animals↗
PubMed1978

Role of the serum estrogen-binding protein in the control of tissue estradiol levels during postnatal development of the female rat.

The role of the serum estrogen-binding protein (EBP) in the control of tissue estradiol levels during postnatal development of the female rat was examined. The estradiol-binding capacity of serum from the 1-day-old rats far exceeded the physiological level of estradiol in serum. The binding capacity decreased exponentially during the first 5 weeks of life to reach the low adult level at about the time of vaginal opening on day 37. From these observations one would predict that EBP would bind estradiol in the serum of the neonate, thereby preventing tissue uptake of the hormone. As the levels of EBP decline with advancing age, there should be a corresponding shift in the distribution of estradiol from serum to tissues. We have taken in vivo and in vitro approaches to evaluate these proposals. Female rats of various ages (1 day to 1 yr old) were sacrificed 1 h after [3H]estradiol injection and the radioactivity in serum and tissues was determined. During the first 11 days of life, the concentration of [3H]estradiol in serum was greater than the concentration of this hormone in estrogen-sensitive (uterus) and insensitive (lung, cerebral cortex, and diaphragm) tissues. Tissue to serum ratios of [3H]estradiol increased progressively between 13-34 days and then plateaued at about the time of puberty (37 days of age) at levels which were 50- to 150-fold greater than those observed in the neonate. The increase in tissue to serum ratios of [3H]estradiol during postnatal development probably resulted from the decline in serum EBP, since injection of neonatal serum into 28-day-old rats reduced tissue to serum ratios of [3H]estradiol to levels which were similar to those observed in 16-day-old animals. To determine the effects of EBP on uterine uptake of estradiol in vitro, uteri from 21-day-old rats were incubated with [3H]estradiol and serum obtained from rats of various ages. As the concentration of serum EBP declined with advancing serum donor age, there was a corresponding increase in the uterine uptake of [3H]estradiol. These results suggest that the decline in EBP is responsible for the progressive increase in tissue to serum ratios of estradiol during the first 5 weeks of life. It is suggested that the increase in tissue to serum ratios of estradiol between days 13-37 postpartum is an important factor in the initiation of estrogenic events during postnatal sexual maturation in the female rat.

Aging↗