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Biomedical subjects

R C Moore

Publications and source records attributed to R C Moore.

At least 37 records · Page 2Linked to original sources
PubMed1994

Progesterone and EGF inhibit mouse mammary gland prolactin receptor and beta-casein gene expression.

Regulation of mouse mammary gland long-form prolactin receptor (PRL-RL) mRNA levels by progesterone and epidermal growth factor (EGF) and the relationship between PRL-RL and beta-casein gene expression were examined in vivo and in vitro. PRL-RL and beta-casein mRNA levels increased approximately 6- and 15-fold from the pregnant to the lactating period, respectively, when normalized to the level of beta-actin mRNA. Ovariectomy of pregnant mice rapidly reduced the serum concentration of progesterone and increased the level of PRL-RL and beta-casein mRNAs approximately three- and fourfold compared with sham-operated animals 24 h after the operation. Injection of progesterone, but not estrogen, inhibited the increase in both mRNA levels. PRL-RL and beta-casein mRNA levels in cultured mammary epithelium increased in response to insulin, hydrocortisone, and prolactin, whereas progesterone or EGF caused inhibition. The combination of EGF and progesterone produced a greater inhibition than either hormone alone. These results indicate that both progesterone and EGF serve as negative regulators of lactogenesis.

Animals↗
PubMed1993

Time sequence of events leading to chromosomal aberration formation.

Investigations have been carried out which have measured the influence of the repair polymerases on the yield of different types of chromosomal aberrations. The studies were mainly concerned with the effect of inhibiting the polymerases on the yield of aberrations. The polymerases fill in single strand regions, and the fact that their inhibition affects the yield of aberrations suggests that single strand lesions are influential in aberration formation. The results indicate that-- 1. There are two actions of polymerases in clastogenesis. One is in their involvement in a G2 repair system, in which the pair of chromatids is concerned, and which does not yield aberrations unless the inhibition is still operating when the cells enter mitosis. The second also operates in G1 and S, and is such that when repair is inhibited, further damage accrues. 2. The second action is affected by inhibiting polymerase but operates even when the repair enzymes are active. 3. The production of chromosomal exchanges involves a series of reactions, some of which are reversible. 4. The time span over which the reactions occur is much longer than has been envisaged previously (e.g., most of a cell cycle).

Animals↗
PubMed1993

The influence of growth medium on the yield of X-ray-induced chromatid exchanges in the presence and absence of aphidicolin.

The frequency of exchanges in JU56 cells irradiated in the G2 phase in the presence and absence of the polymerase inhibitor aphidicolin (APC), and in the presence of a range of concentrations of cysteine was measured. It was found that in the absence of cysteine, incubation for 2 h with APC had no effect on the yield. Addition of cysteine at concentrations of 50-250 mg/l reduced the frequency of exchanges, and at these concentrations the frequency was increased by incubation with APC. At higher concentrations, the yield was reduced and incubation with APC did not elevate it. In following experiments, it was found that incubation with cysteine for a period of longer than 10 minutes was necessary before APC affected the yield of exchanges.

Animals↗
PubMed1993

Chromosomal aberration types in cells at the second division after irradiation in G1 or G2.

Cultures of JU-56 cells were irradiated in either G1 or G2 and examined either in their first post-irradiation metaphase (in diploids) or in their second post-irradiation metaphase (in colcemid-induced tetraploids). The timing of fixation, together with tritiated thymidine pulse labelling, allowed selection for scoring only metaphases of cells that were in the G1 or G2 phase of the cell cycle during irradiation. With G1 irradiation it was found that many of the aberrations observed at the first division were not present (as derivatives) at the second division, and also that new aberrations were found at the second division, which were not derived from aberrations at the first division. Clonogenic survival was also measured in populations of cells irradiated in G1. It was found that cells containing chromosomal aberrations at the first division were not numerous enough to explain lack of survival. When frequencies of aberrations following G2 irradiation scored at the second division were compared with those scored at the first, there was a significant increase in dicentrics as compared with their progenitor asymmetrical chromatid interchanges, and of mirror-image dicentrics as compared with their progenitor sister unions. A substantial number of sister unions were also observed at the second division. We conclude that some aberrations are lost during the interphase between the first and the second post-irradiation metaphase and that new chromosomal aberrations arise during the second post-irradiation interphase.

Animals↗
PubMed1991

Plateletpheresis with the COBE spectra single needle access option.

A group of modifications, including a reservoir bag in the return circuit, has been devised to allow single needle plateletpheresis with the COBE Spectra. We compared the number and quality of platelets collected from 10 subjects in paired donations with single and dual needle protocols. There was no evidence of hemolysis with either protocol. Mean (+/- SD) platelet yields were 3.61 +/- 1.47 x 10(11) with two needles and 3.31 +/- 1.31 x 10(11) with the single needle procedure (P = .13). Mean leukocyte levels (standard manual counting chamber) were 1.0 +/- 1.7 x 10(7) and 1.2 +/- 1.0 x 10(7), respectively (p = .78). pH values during storage were acceptable in both groups of concentrates, and there were no significant differences between the single needle and dual needle concentrates in morphology scores or beta-thromboglobulin levels at 0, 1, 3, or 5 days of storage. Thus the single needle modification produced platelets that were comparable in quantity and quality to those from the standard dual needle plateletpheresis protocol.

Blood Donors↗
PubMed1991

Cyclic AMP inhibits and putrescine represses expression of the speA gene encoding biosynthetic arginine decarboxylase in Escherichia coli.

The speA gene of Escherichia coli encodes biosynthetic arginine decarboxylase (ADC), the first of two enzymes in a putrescine biosynthetic pathway. The activity of ADC is negatively regulated by mechanisms requiring cyclic AMP (cAMP) and cAMP receptor protein (CRP) or putrescine. A 2.1-kb BamHI fragment containing the speA-metK intergenic region, speA promoter, and 1,389 bp of the 5' end of the speA coding sequence was used to construct transcriptional and translational speA-lacZ fusion plasmids. A single copy of either type of speA-lacZ fusion was transferred into the chromosomes of Escherichia coli KC14-1, CB806, and MC4100, using bacteriophage lambda. The speA gene in lysogenized strains remained intact and served as a control. Addition of 5 mM cAMP to lysogenic strains resulted in 10 to 37% inhibition of ADC activity, depending on the strain used. In contrast, the addition of 5 or 10 mM cAMP to these strains did not inhibit the activity of beta-galactosidase (i.e., ADC::beta-galactosidase). Addition of 10 mM putrescine to lysogenized strains resulted in 24 to 31% repression of ADC activity and 41 to 47% repression of beta-galactosidase activity. E. coli strains grown in 5 mM cAMP and 10 mM putrescine produced 46 to 61% less ADC activity and 41 to 52% less beta-galactosidase activity. cAMP (0.1 to 10 mM) did not inhibit ADC activity assayed in vitro. The effects of cAMP and putrescine on ADC activity were additive, indicating the use of independent regulatory mechanisms. These results show that cAMP acts indirectly to inhibit ADC activity and that putrescine causes repression of speA transcription.

Bacteriophage lambda↗
PubMed1990

DNA polymerase alpha does not mediate G0-G1 increase in yield of X-ray-induced exchange aberrations in human peripheral blood lymphocytes.

We report experiments to test the hypothesis that the increased yield of dicentric chromosomes observed in human peripheral blood lymphocytes treated with X-rays during the G1 phase of their first cell cycle, as compared with the yield when the cells are treated in their G0 phase prior to phytohemagglutinin stimulation, is a manifestation of the recently-reported conversion of an inactive form of DNA polymerase alpha to its active form as the PHA-stimulated cells pass from G0 into G1 (Sylvia et al., 1988). The specific polymerase alpha inhibitor butylphenyl deoxyguanosine was used as an X-ray post-treatment. The results show that polymerase alpha is not involved.

Cell Cycle↗
PubMed1990

Nucleotide sequence and analysis of the speA gene encoding biosynthetic arginine decarboxylase in Escherichia coli.

The DNA sequence of a 3.23-kilobase fragment of the Escherichia coli chromosome encoding biosynthetic arginine decarboxylase (ADC) was determined. This sequence contained the speA open reading frame (ORF) as well as partial speB and metK ORFs. The ADC ORF is 1,974 nucleotides long; the deduced polypeptide contains 658 amino acids with a molecular size of 73,980 daltons. The molecular weight and predicted ADC amino acid composition are nearly identical to the amino acid analysis of purified ADC performed by Wu and Morris (J. Biol. Chem. 248:1687-1695, 1973). A translational speA-lacZ fusion, pRM65, including 1,389 base pairs (463 amino acids) of the 5' end of speA was constructed. Western blots (immunoblots) with beta-galactosidase antisera revealed two ADC::beta-galactosidase fusion proteins in E. coli bearing pRM65: 160,000 and 156,000 daltons representing precursor and mature hybrid proteins, respectively. The predicted amino acid sequence of ADC contains a region of six amino acid residues found in two bacterial diaminopimelic acid decarboxylases and three eucaryotic ornithine decarboxylases. This conserved sequence is located approximately eight amino acids from the putative pyridoxal phosphate-binding site of ADC and is predicted to be involved in substrate binding.

Amino Acid Sequence↗