Biomedical subjects

C J Moore

Publications and source records attributed to C J Moore.

At least 55 records · Page 3Linked to original sources

PubMed1993

Phospholipase A2 activation influences the processing and secretion of the amyloid precursor protein.

The phospholipase A2 (PLA2) inhibitors quinacrine, manoalide and scalaradial inhibit the carbachol-stimulated secretion of the amyloid precursor protein (APP) from cells transfected with the human m1 muscarinic receptor. Conversely, activation of PLA2 by melittin increases secretion of an apparently immature species of APP from these cells. These results implicate PLA2 in regulating APP processing and secretion, which may have important implications for understanding the pathogenesis of Alzheimer's Disease.

Amyloid beta-Protein Precursor↗

PubMed1993

High technology to simplify the planning and delivery of radiotherapy.

Two techniques for the automatic selection of individual leaf positions of a Philips multi-leaf collimator are described. Target volumes are identified either on simulator images or on cross-sectional images from CT or MR scanners. The setting of each leaf is computed to position the beam edge to cover the target with an appropriate, user defined, margin. An important consideration in the development of the system was its robustness and so the applications initially implemented have been relatively simple, comprising single field, parallel opposed fields and coplanar 4 field box techniques. Attention has been paid to the overall integrity of the planning and treatment delivery process. Before treatment commences, the beam shapes, which have been generated by the computer and transferred to the MLC control computer over a local area network, are checked against a printed template representing each beam. All data used for planning is archived and is accessible for review or, if necessary, for treatment modification.

Humans↗

PubMed1993

Porphyrobacter neustonensis gen. nov., sp. nov., an aerobic bacteriochlorophyll-synthesizing budding bacterium from fresh water.

Four strains of orange- or red-pigmented bacteria isolated from freshwater surfaces were shown to synthesize bacteriochlorophyll under aerobic conditions. These strains shared unusual morphological features, such as acellular stalks, crateriformlike structures, and buds, with bacteria in the order Planctomycetales. However, comparisons of 16S rRNA sequences showed them to be members of the alpha-4 subdivision of the class Proteobacteria and most closely related to the marine aerobic bacteriochlorophyll-synthesizing bacterium Erythrobacter longus. They also differ from members of the Planctomycetales phenotypically in their synthesis of bacteriochlorophyll and possession of a peptidoglycan cell wall. They can be distinguished from E. longus on the basis of their 16S rRNA sequence, the G+C content of their DNA, cellular fatty acid composition, and carbon substrate spectrum. A new genus, Porphyrobacter, with a single species, P. neustonensis gen. nov., sp. nov., is proposed for these strains. The type strain is ACM 2844.

Bacteria, Aerobic↗

PubMed1992

Computer-assisted generation of multi-leaf collimator settings for conformation therapy.

Techniques for the automatic set up of the individual leaf positions of a Philips multi-leaf collimator system to cover a defined target volume are described. Tumour outline data for multi-field treatments may be obtained from one of two techniques, either from simulator images or from cross-sectional computed tomography (CT) slices. In the first technique, simulator images are digitized directly from image intensifier video signals or from conventional film radiographs using a CCD camera. Corrections for image distortion are carried out before reformatting the digitized images to a common data structure. Target outlines are subsequently traced interactively on the digital image to create an outline file. In the second technique, target volumes are defined on several individual CT slices and these are then used to obtain projected graphical views from any desired angle. In both techniques, a scaled graphical representation of leaf positions is then displayed and set relative to the outer edge of the target outline. Both techniques allow interactive repositioning of single leaves when required, or the operator can specify a margin around the projected target volume. Leaf prescription data files are created and are transferred via a Decnet-OSI-Opennet network link to an Intel microcomputer, which is used to drive the device itself. Examples of both techniques are given.

Humans↗

PubMed1991

In vitro study of placental trophoblast calcium uptake using JEG-3 human choriocarcinoma cells.

During human fetal development, placental syncytiotrophoblasts actively transport calcium from the maternal to the fetal circulation. Two functional components, a cytosolic Ca2(+)-binding protein (CaBP) and a Ca2(+)-ATPase have been identified in the syncytiotrophoblasts of the chorionic villi. We report here the calcium uptake properties of a human choriocarcinoma cell line, JEG-3, which was used as an in vitro model cell system for the syncytiotrophoblasts. In culture, JEG-3 proliferated as large syncytial aggregates expressing typical syncytiotrophoblast markers. 45Ca uptake by JEG-3 was a substrate- and temperature-dependent, membrane-mediated active process that exhibited linear kinetics for up to 7 min. Both the CaBP and the Ca2(+)-ATPase were expressed by JEG-3, on the basis of biochemical, histochemical, immunochemical and or mRNA assays. Immunohistochemistry and in situ hybridization revealed that JEG-3 cells were heterogeneous with respect to the expression of the CaBP. The Ca2(+)-ATPase activity of JEG-3 was similar to the placental enzyme in terms of sensitivity to specific inhibitors, and was detected histochemically along the cell membrane. Fura-2 Ca2+ imaging revealed that calcium uptake by JEG-3 was not accompanied by a concomitant increase in cytosolic [Ca2+], suggesting a specific Ca2+ sequestration mechanism. The involvement of calciotropic hormonal regulation was evaluated by studying the response of JEG-3 to 1,25-dihydroxy vitamin D3. Calcium uptake was significantly stimulated in a dose-dependent manner by a 24-h treatment of the cells with 1,25-dihydroxy vitamin D3 (optimal dose approximately 0.5 nM); the CaBP level doubled whereas steady-state CaBP mRNA did not, suggesting that CaBP expression was regulated by 1,25-dihydroxy vitamin D3. These observations strongly suggest that the JEG-3 human choriocarcinoma cells should serve as a convenient in vitro model system for studying the cellular mechanism and regulation of transplacental calcium transport.

Biological Transport, Active↗

PubMed1989

A custom-designed computer network for a dental clinical school.

A local area computer network has been designed and implemented to service predominantly the patient-related administrative needs of the Westmead Dental Clinical School. The appropriate software has been developed in-house over a period of time and introduced as the complexity and volume of the tasks increased and as more sophisticated hardware became available. The present arrangement utilizes NEC APC III and NEC APC IV computers with ACSinet networking hardware added to an OMNInet system. Primary functions include the management of extensive patient waiting lists (up to 16,000), treatment lists and laboratory work flow, as well as the provision of a wide range of related statistical information. Wordprocessing is a large scale daily activity. More specialized secondary functions include monitoring of patients allocated to dental students, support of the management of appointments, recalls, mailing lists and some specific research projects including data collection for a quality assurance programme. The network functions separately but simultaneously alongside an extensive hospital-wide VAX cluster and has greatly simplified the handling and management of a vast array of data essential to the management and evaluation of the treatment provided in the Dental Clinical School.

Computer Systems↗

PubMed1988

Comparison of 7,12-dimethylbenz[a]anthracene metabolism and DNA binding in mammary epithelial cells from three rat strains with differing susceptibilities to mammary carcinogenesis.

The capacity of polycyclic aromatic hydrocarbons such as 7,12-dimethylbenz[a]anthracene (DMBA) to induce mammary carcinomas has been studied in three rat strains. Wistar/Furth (WF) rats are highly susceptible to DMBA-induced mammary carcinogenesis, Copenhagen (Cop) rats are completely resistant, and Fischer 344 (F344) rats have an intermediate susceptibility. We have previously shown that WF rats possess 'enhancer genes', which enhance susceptibility to induced mammary cancer. Cop rats, however, possess a single 'suppressor' gene which confers complete resistance to mammary cancer. Both gene types are apparently absent in F344 rats. In order to determine possible mechanisms of action of these enhancer and suppressor genes, we have examined DMBA metabolism and DNA binding in mammary epithelial cells isolated from each rat strain. Quantitative analyses of both metabolism and DNA binding indicate no significant differences among the strains. In addition, HPLC analyses of DMBA metabolites and DMBA-DNA adducts were essentially identical. These data suggest that the genes controlling susceptibility and resistance to mammary carcinogenesis in these rat strains are likely to be active at later stages of the carcinogenic process.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1988

32P-postlabeling analysis of DNA adducts in human and rat mammary epithelial cells.

The etiology of human breast cancer is currently undefined. However, it has been hypothesized that exposure to chemical carcinogens may be an important factor. Extrapolation from rodent models for chemically-induced mammary cancer suggests the possibility that human mammary epithelial cells in situ might contain DNA adducts due to exposure to environmental chemicals. We have therefore screened breast epithelial cells from 10 donors for the existence of DNA adducts using the 32P-postlabeling assay. In order to validate this analysis technique, we also examined the DNA adducts formed in human mammary cells exposed to benzo[a]pyrene (B[a]P) in vitro, and adducts formed in rat mammary epithelial cells exposed to B[a]P in vitro and in vivo. Confirming previous results using HPLC analysis of [3H]B[a]P-DNA adducts, the major B[a]P-DNA adduct formed by human mammary epithelial cells in vitro was (+)-anti-B[a]P-7,8-dihydrodiol-9,10-epoxide (BPDE):deoxyguanosine. This adduct did not appear to be formed by rat mammary cells exposed to B[a]P in vitro. However, 32P-postlabeling analysis of mammary epithelial cell DNA from rats exposed to B[a]P in vivo indicated that (+)-anti-BPDE-deoxyguanosine was a major B[a]P-DNA adduct under these exposure conditions. When the mammary epithelial cells from 10 human donors were screened for DNA adducts formed in situ, cells from three donors exhibited distinct adduct patterns. None of these adducts appeared to be (+)-anti-BPDE-deoxyguanosine. The existence of DNA adducts in human mammary epithelial cells in situ, coupled with the data indicating that rat mammary cells form different B[a]P adducts in vitro and in situ, suggests the need for further study of human breast cell adducts.

Adenosine Triphosphate↗

PubMed1987

Interspecies differences in the major DNA adducts formed from benzo(a)pyrene but not 7,12-dimethylbenz(a)anthracene in rat and human mammary cell cultures.

Mammary epithelial cells from rats and humans show both quantitative and qualitative species- and carcinogen-specific differences in their abilities to activate benzo(a)pyrene (B(a)P) and 7,12-dimethylbenz(a)anthracene (DMBA). Previous studies of the DNA binding of these compounds in mammary epithelial cells demonstrated that rat cells bound relatively more DMBA than B(a)P to DNA under identical treatment conditions, while the opposite pattern was exhibited by human mammary epithelial cells. The specific DNA adducts formed in these cells after 24-h incubations with [3H]DMBA and [3H]B(a)P were analyzed to determine if there were qualitative as well as quantitative differences in the amounts of individual adducts. Similar proportions of specific DMBA-DNA adducts were found in both rat and human cells, although the total amount of adducts formed was significantly higher in the rat cells. In contrast, an essentially qualitative species-specific difference was observed in the major B(a)P-DNA adduct present in the rat and human cells. The major B(a)P adduct formed in the human mammary epithelial cells was identified as the (+)-anti-B(a)P-7,8-dihydrodiol-9, 10-epoxide(BPDE)-deoxyguanosine adduct. However, this adduct was formed at very low levels in the rat mammary epithelial cells. The rat cells contained a large proportion of syn-BPDE adducts, and other unidentified B(a)P-DNA adducts. The high level of the (+)-anti-BPDE-deoxyguanosine adduct in the human but not the rat mammary cells is consistent with the potential role of (+)-anti-BPDE in the high mutagenic activity of B(a)P in the cell-mediated mutagenesis assays using the human mammary cells as activators, and the low mutagenic activity of B(a)P when rat cells were used as activators. The quantitative differences in the activation of DMBA by cells from these two species are also consistent with the cell-mediated mutagenic activities of DMBA using these cells as activators. These results suggest that the higher carcinogenic activity of DMBA compared to B(a)P in the rat mammary gland may not be indicative of the relative carcinogenic potencies of these compounds for human mammary cells.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

PubMed1987

Quantitation of benzo(a)pyrene and 7,12-dimethylbenz(a)anthracene binding to nuclear macromolecules in human and rat mammary epithelial cells.

Our laboratory has developed virtually identical techniques for the isolation and culture of mammary epithelial cells (MEC) from rats and humans. In a cell-mediated mutagenesis assay, rat MEC activated 7,12-dimethylbenz(a)anthracene (DMBA) but not benzo(a)pyrene [B(a)P] to mutagenic forms, and the opposite pattern was found with human MEC. These species-specific patterns were not readily explained by either qualitative or quantitative differences in Phase I metabolism of these compounds. In contrast, relative levels of covalent binding of these compounds to DNA in the human and rat cells under identical assay conditions generally parallel the pattern of the mutagenesis results, while not reflecting the absolute levels of metabolism in each system. The ability of the rat MEC to bind relatively higher levels of DMBA than B(a)P to nuclear DNA, and the reversed pattern in human MEC, was found at all incubation times tested between 6 and 48 h. Culture density was found to exert a greater effect on the levels of PAH-DNA binding in rat than in human cells, but in neither case did it affect the ratio of DMBA to B(a)P binding within a species. C2SO4 gradient separation of nuclear macromolecules from PAH-treated MEC revealed that the relative DNA binding levels of DMBA and B(a)P did not correlate with relative levels of nuclear protein binding. For both species, nuclear (DNA + protein) binding levels of B(a)P were approximately 2-fold higher than DMBA. However, these binding levels were 4 to 5-fold higher for both carcinogens in the human than in the rat MEC. The species-specific patterns of PAH activation shown by these cells suggest that caution should be used in extrapolating rodent carcinogenesis data to humans, for either quantitative or qualitative purposes.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1987

Induction of mammary cytochromes P-450: an essential first step in the metabolism of 7,12-dimethylbenz[a]anthracene by rat mammary epithelial cells.

Rat mammary epithelial cells (RMEC) in culture have been shown to activate polycyclic aromatic hydrocarbon (PAH) carcinogens. This study investigates the role of mammary cytochrome P-450 monooxygenases in these metabolic processes. Monooxygenation of 7,12-dimethylbenz[a]anthracene (DMBA) by RMEC in culture exhibited a 6-h lag period before reaching a constant rate. The mechanism for this time-dependent expression of DMBA monooxygenase activity was investigated in lysed cells, where both conjugation and in situ induction of P-450 are prevented. Although metabolism of DMBA by untreated RMEC lysates was undetectable (less than 1 pmol/mg cell protein/h), prior exposure of cultured cells to benz[a]anthracene (BA) induced DMBA metabolism, (approximately 100 pmol/mg cell protein/h). BA pretreatment also eliminated the lag period for metabolism of DMBA by cultured RMEC but did not prevent additional induction of DMBA monoxygenase activity by the substrate. The distribution of monooxygenated DMBA metabolites formed by BA-induced cell lysates was clearly different from that obtained with purified P-450c, the predominant PAH-inducible isozyme in rat liver. For example, the carcinogen precursor DMBA 3,4-dihydrodiol, which is not formed by P-450c, was a clearly detectable product in RMEC. The low epoxide hydratase activity of BA-induced lysate (approximately 400-fold lower compared to that in the liver) limited formation of all DMBA dihydrodiols. The formation of DMBA 3,4-dihydrodiol increased by 5-fold following addition of exogenous purified epoxide hydratase. The DMBA monooxygenase activity of BA-induced RMEC lysates was completely inhibited by alpha-naphthoflavone but was only partially inhibited (50%) by a polyclonal antibody raised against cytochrome P-450c. Anti P-450c completely inhibited formation of some of the metabolites, partially inhibited formation of others and notably stimulated formation of DMBA 3,4-dihydrodiol by 60%. A polyclonal antibody that recognized both rat hepatic P-450a and a group of P-450 isozymes related to P-450h, and which totally inhibited DMBA 3,4-dihydrodiol formation by rat liver microsomes, did not inhibit formation of any DMBA metabolite in RMEC, including DMBA 3,4-dihydrodiol. Western blot analyses of RMEC homogenates demonstrated that BA pretreatment induces P-450c, but not P-450a or any of the P-450h-related isozymes. We conclude that metabolism of DMBA by RMEC depends on induction of P-450c and at least one additional form of cytochrome P-450 which is immunochemically distinct from rat hepatic P-450a and P-450h related isozymes, but is sensitive to alpha-naphthoflavone.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1987

Differentiation of Bordetella avium and related species by cellular fatty acid analysis.

The fatty acids of 18 strains of Bordetella avium, 3 strains of Alcaligenes faecalis, 5 strains of Bordetella bronchiseptica, and 12 strains of a B. avium-like organism were examined by gas chromatography-mass spectrometry. The presence of a significant amount of the acid 2-OH C14:0 characterized B. avium and the B. avium-like organism. B. avium and the B. avium-like organism differed in their relative concentrations of C16:1 and 3-OH C14:0 acids. B. bronchiseptica and A. faecalis were distinguishable by comparison of the relative concentrations of C18:0 and C18:1 acids.

Alcaligenes↗

PubMed1987

The relationship between the bladder and the cervix in patients undergoing intracavitary therapy.

Previous studies have shown a poor correlation between bladder damage and bladder dosage in patients treated with radiation therapy, including intracavitary therapy for uterine tumours. This study was undertaken to investigate prospectively the relationship between the cervical os and the bladder in patients undergoing intracavitary treatment. The computed tomography scans of 59 patients undergoing intracavitary treatment were analysed. The upper limit of the undistended bladder relative to the os extended from 5.5 cm cephalic to the cervix to 4.0 cm below it. The distance from the central tube to the posterior bladder wall at the level of the cervix ranged from 1.5 cm to 4.2 cm. This was positively associated with size of ovoid (p = 0.022), though with considerable individual variation. A separate analysis failed to show a consistent correlation with age or stage of disease. Thirty-nine of the 59 patients (65.5%) had asymmetrical bladders. Of these, half had "slight" asymmetry and the others had "marked" asymmetry. The thickness of the vesico-vaginal septum varied from 0.5 cm to 2.9 cm but was difficult to assess in some patients. In patients treated with medium-sized ovoids and those with Stage IB and IIB disease, the distance to the bladder base is greatest, though there is marked individual variation. These investigations reveal a marked variation in bladder position relative to the cervix in patients undergoing intracavitary therapy. The position of the bladder cannot be accurately predicted by any of these clinical criteria and requires to be defined by a radiological technique in the individual patient.

Brachytherapy↗

PubMed1986

Determination of free choline in plasma and erythrocyte samples and choline derived from membrane phosphatidylcholine by a chemiluminescence method.

A sensitive chemiluminescence method for assay of choline which has been developed for analysis of erythrocyte and plasma levels of choline is reported here. This method includes a charcoal purification step which yields consistent results with plasma and erythrocyte extracts. Further, choline derived from membrane phosphatidylcholine may also be measured by an extension of this method following digestion with phospholipase D. This method has been used to study abnormal levels of erythrocyte choline that occur in cluster headache patients compared to control subjects and migraine patients. In addition, the time course of changes in plasma and erythrocyte choline following a fatty meal have been monitored. Plasma choline levels rise to a maximum between 1 and 3 h after the meal and this is followed by a rise in erythrocyte choline levels which are maximal 3 h after the meal.

Cholesterol↗

PubMed1986

Fast computer processing for tissue highlighting in computed tomographic cross-sectional imaging and digital scan projection radiography.

A simple, fast, computer method of simultaneously highlighting edge detail and emphasising soft-tissue contrast is discussed. An objective comparison is made with conventional blurred mask subtraction using the signal-to-noise ratio from phantom scans. The use of the algorithm for inner ear studies and digital scanned projection radiography is presented.

Computers↗

PubMed1986

Interspecies comparison of human and rat mammary epithelial cell-mediated mutagenesis by polycyclic aromatic hydrocarbons.

In order to compare the interactions of procarcinogens with mammary cells from humans and rats, a uniform set of mediated mutagenesis assays has been established. In these assays, species-specific mammary epithelial cells activate procarcinogens, and specific locus mutations are quantitated in cocultured V-79 cells. Mutations were induced in the rat mammary cell coculture system exposed to 7,12-dimethylbenz(a)anthracene but not benzo(a)pyrene. In contrast, in the human mammary cell coculture system benzo(a)pyrene was much more effective than 7,12-dimethylbenz(a)anthracene in the induction of mutations. These results suggest caution in extrapolating carcinogenesis data between rodents and humans. They also suggest that the relationship between the ubiquitous environmental xenobiotic benzo(a)pyrene and the etiology of human breast cancer requires further exploration.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1986

Interspecies comparison of polycyclic aromatic hydrocarbon metabolism in human and rat mammary epithelial cells.

Our laboratory has developed optimized and uniform methods for the isolation and culture of normal mammary epithelial cells from both rats and humans. We have reported that, in a cell-mediated mutagenesis assay, treatment of rat mammary epithelial cells with 7,12-dimethylbenz(a)anthracene, but not benzo(a)pyrene, resulted in significant rates of mutagenesis in cocultured V-79 cells. An opposite mutation pattern was found with human cells under identical conditions. To determine the mechanism of this species-specific difference in polycyclic aromatic hydrocarbon-induced mutagenesis patterns, we then studied the abilities of the human and rat mammary epithelial cells to metabolize benzo(a)pyrene and 7,12-dimethylbenz(a)anthracene. Quantitative levels of carcinogen metabolism were found to be highly dependent on the cell culture densities, although this factor appeared to have little qualitative effect. The most significant qualitative difference in polycyclic aromatic hydrocarbon metabolism between the two species was the ability of the rat, but not the human, mammary epithelial cells to conjugate significant amounts of either polycyclic aromatic hydrocarbon to glucuronic acid. Other aspects of carcinogen metabolism, including production of the precursors to known active metabolites of benzo(a)pyrene and 7,12-dimethylbenz(a)anthracene, were similar though not identical. These results, which address only primary metabolism of the polycyclic aromatic hydrocarbons, do not indicate a simple metabolic explanation for the species-specific pattern found in the mammary cell-mediated mutagenesis assay. They do suggest that the effects of cell culture density must be carefully considered in order to properly analyze either interindividual or species differences in carcinogen metabolism.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1985

Enduring enhancement in frontal cortex dopamine utilization in an animal model of amphetamine psychosis.

It is reported that in rats the repeated intermittent administration of amphetamine produces a long-lasting enhancement in medial frontal cortex dopamine utilization. This change in mesocortical dopamine activity may be involved in the behavioral sensitization produced by psychomotor stimulant drugs, and some of the cognitive abnormalities (e.g. amphetamine psychosis) associated with stimulant drug abuse in humans.

Amphetamine↗