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Biomedical subjects

C D Green

Publications and source records attributed to C D Green.

At least 37 records · Page 2Linked to original sources
PubMed1993

Induction of germ-cell alkaline phosphatase by butyrate and cyclic AMP in BeWo choriocarcinoma cells.

BeWo choriocarcinoma cells synthesize two alkaline phosphatase isoenzymes: germ-cell alkaline phosphatase and tissue-unspecific alkaline phosphatase. We have made use of the differential heat-stabilities of these two isoenzymes to study the induction of germ-cell alkaline phosphatase by sodium butyrate and cyclic AMP (cAMP). Sodium butyrate causes a large induction of germ-cell alkaline phosphatase activity (approx. 35-fold after 96 h) after an initial lag period of 12-24 h. We showed that butyrate increases germ-cell alkaline phosphatase mRNA. Dibutyryl cAMP also induces germ cell alkaline phosphatase (approx. 2.5-fold after 96 h). When optimal concentrations of butyrate and dibutyryl cAMP were added simultaneously to cells, they caused a synergistic induction of activity. This suggested that these compounds use separate mechanisms to induce germ-cell alkaline phosphatase activity and that it is the cAMP moiety of dibutyryl cAMP that induces enzyme activity. This was confirmed by the use of two additional cAMP analogues, 8-(4-chlorophenylthio) cAMP and 8-bromo cAMP, and of two compounds, 3-methyl-1-isobutylxanthine and cholera toxin, which raise the endogenous concentration of cAMP. All four compounds caused a 2-fold increase in enzyme activity. Treatment of cells with 8-(4-chlorophenylthio) cAMP, 8-bromo cAMP and cholera toxin increased germ-cell alkaline phosphatase mRNA between 2- and 7-fold. These data suggest that this alkaline phosphatase isoenzyme is regulated at the level of its mRNA by cAMP, in a manner distinct from that of butyrate.

1-Methyl-3-isobutylxanthine↗
PubMed1993

Placental alkaline phosphatase activity is inversely related to cell growth rate in HeLaS3 cervical cancer cells.

Placental alkaline phosphatase is an inducible enzyme, expressed in HeLaS3 cells, which has been shown to possess protein phosphotyrosine phosphatase activity. Since phosphotyrosine levels are known to increase in actively dividing cells we sought an inverse correlation between PLAP activity and growth rate in HeLaS3 cells. We found that PLAP inducers, Na-butyrate, dexamethasone, bromodeoxyuridine and dibutyryl cAMP caused a dose-dependent reduction in growth rate. Mimosine, an agent that blocks the cell cycle in G1, caused an increase in PLAP activity whilst the mitogen EGF caused a corresponding decrease in PLAP activity. PLAP activity may therefore be related to cell proliferation rate.

Alkaline Phosphatase↗
PubMed1993

The role of four oestrogen-responsive genes, pLIV1, pS2, pSYD3 and pSYD8, in predicting responsiveness to endocrine therapy in primary breast cancer.

The expression of four oestrogen-responsive genes in 118 immunohistochemically defined primary breast tumours has been determined by northern analysis. While all the genes are induced by oestrogen in oestrogen receptor (ER)-positive cell lines, their behaviour is different in breast tumour biopsies. This behaviour can be divided into two groups; the first containing the genes, pLIV1 and pLIV2 (pS2), which both show a significant association with ER status (P = 0.001) and a corresponding inverse relationship with epidermal growth factor receptors (EGFR) (P = 0.01 and P = 0.08, respectively). In addition, the mRNA levels of both pLIV1 and pS2 are greater in ER-positive compared to ER-negative disease (P = 0.001). While a small number of ER-negative tumours were positive for either pLIV1 (12%) or pS2 (9%), we failed to observe co-expression of pLIV1 and pS2 in ER-negative disease. In ER-positive disease, four tumour populations were identified; ER+pLIV1-pS2-, ER+pLIV1-pS2+, ER+pLIV1+pS2- and ER+pLIV1+pS2+. Interestingly, the levels of pLIV1 and pS2 when co-expressed were significantly greater in ER+pLIV1+pS2+ tumours compared to either of the ER+pLIV1+pS2- (P = 0.03) or ER+pLIV1-pS2+ (P = 0.01) mixed phenotypes. Unlike pLIV1 and pS2, pSYD3 and pSYD8 belong to a group of genes which are expressed in the majority of tumours regardless of ER and EGFR status. However, lower pSYD8 mRNA levels were detected in moderately EGFR-positive disease (P = 0.06) while both pSYD3 positivity (P = 0.01) and mRNA levels (P = 0.001) were increased in highly proliferating tumours as shown by Ki67 immunostaining. These genes provide additional markers which, in conjunction with other parameters, may help to determine the likelihood of a given tumour to respond to endocrine therapy.

Biomarkers, Tumor↗
PubMed1992

Expression of the Large ATP Synthase Gene Cluster in Spinach Plastids during Light-Induced Development.

The large ATP synthase gene cluster in spinach (Spinacia oleracea) plastids encodes four of the six chloroplast-encoded ATP synthase subunits. Expression of this cluster was examined to determine its response to light-induced plastid development. Spinach plastid transcripts were isolated from etiolated tissues, etiolated tissues exposed to 24 h of light, young (1-3 cm) leaves, and mature (8-10 cm) leaves. Transcript levels were examined from each developmental stage as a function of either the quantity of total RNA or gene dosage. The relative transcriptional activity of this gene cluster at each of the four developmental stages was also investigated. The stability of these transcripts was deduced by comparing the transcriptional activity with steady-state transcript levels. During the initial 24 h of light-induced development of an etioplast to a chloroplast, transcription decreases in conjunction with increased transcript stability. Transcriptional activity of this cluster per genome then increases between the 24-h and young stages, with a concomitant decrease in the stability of the transcripts. As the young chloroplast matures, the transcripts from this cluster again become markedly more stable, and the transcription of this set of genes declines. Therefore, the regulation of the expression of this cluster is dependent upon a complex interaction between transcriptional and posttranscriptional factors throughout light-induced plastid development.

Journal Article↗
PubMed1991

Temporal patterns of lost milk production following clinical mastitis in a large Michigan Holstein herd.

Cows with three hundred and sixteen cases of clinical mastitis were sampled by microbiologic culture during a 6-mo period on a 1700-cow Michigan Holstein dairy farm. Daily milk weights were obtained on all cows before clinical onset and for 60 d after onset. Predicted post-mastitis production, projected on the basis of premastitis production and the lactation curves of contemporary non-mastitic herdmates, was compared with actual daily milk production during the 60 d following clinical onset. Cows experiencing clinical mastitis produced approximately 341 kg less salable milk during the 60 d after clinical onset compared with projected production. This milk loss included both decreased production and milk withheld from market following antibiotic treatment. Pluriparous cows lost 2.06 times as much milk as first lactation cows, and cows with mastitis occurring before 150 d in lactation lost 1.40 times as much milk when compared with other cows. Cows with mastitis occurring in the winter showed a milk loss 1.37 times greater than cows with mastitis in summer. The identity of the mastitis agent isolated from the clinical case was not strongly associated with the drop in milk production in the 60 d following clinical onset.

Animals↗
PubMed1989

A simple purification procedure for lambda gt bacteriophage DNA with hybridization size screening for isolation of longest length cDNA clones.

An improved procedure for isolating lambda DNA and screening lambda gt10 or lambda gt11 libraries is described. Recombinant lambda gt11 bacteriophage particles (150,000) were amplified on three agarose plates (50,000 per plate) with Escherichia coli Y1090 as plating bacteria. After confluent lysis, recombinant bacteriophage was extracted with SM buffer. Bacterial debris was removed by centrifugation. A small aliquot of amplified lambda gt11 bacteriophage was kept to rescreen the bacteriophage, should a large or full-length clone be found to be present, after analysis of the size of the cDNA inserts. The major portion of the bacteriophage particles was purified by treatment with equilibrated DEAE-cellulose, pH 7.5. Purified phage particles were precipitated with polyethylene glycol from the DEAE supernatant and extracted with phenol, phenol-chloroform, and chloroform. Such lambda gt11 DNA was readily digested with EcoRI. Liberated insert cDNA was separated on 1.2% agarose gels, transferred onto a nylon membrane, and hybridized with an alkaline phosphatase cDNA probe in an iterative procedure that allows isolation of the largest cDNA clones present in the library. We have used this procedure to isolate a full-length alkaline phosphatase cDNA. The method is quick, reliable, and less costly than conventional procedures for the isolation of full-length cDNAs.

Bacteriophage lambda↗
PubMed1988

Effects of oestrogen on the expression of a 4.4 kb mRNA in the ZR-75-1 human breast cancer cell line.

A cDNA library has been constructed from the poly(A)+ mRNA of oestrogen-stimulated ZR-75-1 human breast cancer cells. Screening by differential hybridization has identified eight clones which are stimulated between 4- and 16-fold by oestrogen. Two clones (pLIV-1) that are stimulated 4-fold, hybridize to three different mRNA species. A further five recombinants encode for a mRNA 600 bp long which is induced greater than 16-fold and have been shown to cross-hybridize to the oestrogen-responsive clone, pS2, isolated from the MCF-7 breast cancer cell line. Oestradiol was shown to be without detectable effect upon the expression of mRNA for dihydrofolate reductase, which is reported to be oestrogen regulated in MCF-7 cells. Actin gene expression is also unresponsive to oestradiol in ZR-75-1 cells. These results suggest that pLIV-1 represents a previously unidentified mRNA that may be involved in the oestrogen-regulated growth of ZR-75-1 human breast cancer cells.

Breast Neoplasms↗
PubMed1986

Seasonal variations in the stable carbon isotopic signature of biogenic methane in a coastal sediment.

Systematic seasonal variations in the stable carbon isotopic signature of methane gas occur in the anoxic sediments of Cape Lookout Bight, a lagoonal basin on North Carolina's Outer Banks. Values for the carbon isotope ratio (delta 13C) of methane range from -57.3 per mil during summer to -68.5 per mil during winter in gas bubbles with an average methane content of 95%. The variations are hypothesized to result from changes in the pathways of microbial methane production and cycling of key substrates including acetate and hydrogen. The use of stable isotopic signatures to investigate the global methane cycle through mass balance calculations, involving various sediment and soil biogenic sources, appears to require seasonally averaged data from individual sites.

Anaerobiosis↗
PubMed1986

Polyamines and growth regulation of cultured human breast cancer cells by 17 beta-oestradiol.

The growth of ZR-75-1 cells, a line of human breast cancer cells in culture, is stimulated by oestradiol and inhibited by anti-oestrogens. Changes in growth rate caused by these agents are accompanied by changes in activity of ornithine decarboxylase, a rate-limiting enzyme for polyamine synthesis. Furthermore, the growth inhibition caused by tamoxifen, an anti-oestrogen, can be reversed by the addition of spermine, spermidine or putrescine to the cells. Insulin can also stimulate ZR-75-1 cell growth and this is again accompanied by an increase in ODC activity. The reduced cell growth rate observed when the cells become confluent is associated with a marked decrease in ornithine decarboxylase activity. Experiments performed with DFMO, a specific and irreversible inhibitor of ODC, show that this compound can prevent the stimulation of growth by oestradiol and that this may be overcome by the addition of putrescine to the cells. It would appear that increased ODC activity and polyamine synthesis are necessary components of the stimulation of breast cancer cell growth by oestradiol but that other growth regulatory stimuli also may act via this enzyme.

Breast Neoplasms↗
PubMed1983

Serum regulation of the estrogen responsiveness of the human breast cancer cell line MCF-7.

Initially after receiving MCF-7 cells, we were able to confirm their estrogen responsiveness. We observed significant increases in thymidine incorporation, in thymidine kinase activity, and in cell numbers in response to 10(-8) M estradiol. Subsequently, however, the cells failed to show a response to estradiol. A growth response to estradiol could be restored by increasing the serum concentration in the medium. Cells grown in 15% serum (calf or human) responded to estradiol with increased rates of growth and thymidine incorporation and increased activities of thymidine kinase and DNA polymerase. We suggest that there is present in serum a "factor" which can influence the expression of a growth response to estradiol.

Blood↗
PubMed1982

A microcomputer program for analysis of nucleic acid hybridization data.

The study of nucleic acid hybridization is facilitated by computer mediated fitting of theoretical models to experimental data. This paper describes a non-linear curve fitting program, using the 'Patternsearch' algorithm, written in BASIC for the Apple II microcomputer. The advantages and disadvantages of using a microcomputer for local data processing are discussed.

Computers↗
PubMed1982

Effects of massive overdose of epidural morphine sulphate.

In summary, a patient was rapidly injected by error with morphine sulphate 60 mg epidurally. Left bundle branch block and ST segment depression signalled a problem. Respiratory depression occurred 15 minutes later. sympathetic blockade of the lower extremities was not detected. Injections of naloxone reversed the left bundle branch block, and respiratory depression but appeared to be cumulative and resulted in severe pain. A continuous naloxone infusion was effectively titrated to minimize respiratory depression for 19 hours without reversing analgesia. Twenty-four hours after epidural injection, the neurological examination was normal. Epidural morphine analgesia persisted for approximately 38.5 hours.

Electrocardiography↗