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J Gibbons

Publications and source records attributed to J Gibbons.

At least 19 recordsLinked to original sources
PubMed2003

A snapshot of the low temperature stress transcriptome of developing rice seedlings (Oryza sativa L.) via ESTs from subtracted cDNA library.

Rice (Oryza sativa L.) is sensitive to chilling particularly during early seedling development. Given the biochemical complexity of tolerance mechanisms, genetic potential for this trait depends on highly coordinated expression of many genes. We used a simple cDNA subtraction strategy to develop Expressed Sequence Tags (ESTs) that represent an important subset of cold stress-upregulated genes. The 3,084 subtracted cDNA clones represent a total of 1,967 unigenes from 1,354 singletons and 613 contigs. As expected in the developing seedlings, genes involved in basic cellular processes, i.e., metabolism, growth and development, protein synthesis, folding and destination, cellular transport, cell division and DNA replication were widely represented. Genes with stress-related and regulatory functions comprised 23.17% of the total ESTs. These categories included proteins with known function in cellular defenses against abiotic (drought, cold and salinity) and biotic (pathogen) stresses, and proteins involved in developmental and stress response signalling and transcription. Based on the types of genes represented, tolerance mechanisms rely on precise integration of developmental processes with stress-related responses. A large fraction of the ESTs (38.7%) represents unknown proteins. This EST library is a rich source of cold stress-related genes, and supplements for other publicly available libraries for comprehensive analysis of the stress-response transcriptome.

Cold Temperature↗
PubMed2001

Optimization of 4-phenylamino-3-quinolinecarbonitriles as potent inhibitors of Src kinase activity.

Subsequent to the discovery of 4-[(2,4-dichlorophenyl)amino]-6,7-dimethoxy-3-quinolinecarbonitrile (1a) as an inhibitor of Src kinase activity (IC(50) = 30 nM), several additional analogues were prepared. Optimization of the C-4 anilino group of 1a led to 1c, which contains a 2,4-dichloro-5-methoxy-substituted aniline. Replacement of the methoxy group at C-7 of 1c with a 3-(morpholin-4-yl)propoxy group provided 2c, resulting in increased inhibition of both Src kinase activity and Src-mediated cell proliferation. Analogues of 2c with other trisubstituted anilines at C-4 were also potent Src inhibitors, and the propoxy group of 2c was preferred over ethoxy, butoxy, or pentoxy. Replacement of the morpholine group of 2c with a 4-methylpiperazine group provided 31a, which had an IC(50) of 1.2 nM in the Src enzymatic assay, an IC(50) of 100 nM for the inhibition of Src-dependent cell proliferation and was selective for Src over non-Src family kinases. Compound 31a, which had higher 1 and 4 h plasma levels than 2c, effectively inhibited tumor growth in xenograft models.

Animals↗
PubMed2001

An inhibitor of mTOR reduces neoplasia and normalizes p70/S6 kinase activity in Pten+/- mice.

PTEN phosphatase acts as a tumor suppressor by negatively regulating the phosphoinositide 3-kinase (PI3K) signaling pathway. It is unclear which downstream components of this pathway are necessary for oncogenic transformation. In this report we show that transformed cells of PTEN(+/-) mice have elevated levels of phosphorylated Akt and activated p70/S6 kinase associated with an increase in proliferation. Pharmacological inactivation of mTOR/RAFT/FRAP reduced neoplastic proliferation, tumor size, and p70/S6 kinase activity, but did not affect the status of Akt. These data suggest that p70/S6K and possibly other targets of mTOR contribute significantly to tumor development and that inhibition of these proteins may be therapeutic for cancer patients with deranged PI3K signaling.

Alleles↗
PubMed2001

Comparison by restriction fragment differential display RT-PCR of gene expression pattern in bovine oocytes matured in the presence or absence of fetal calf serum.

A novel restriction fragment differential display (RFDD) RT-PCR has been used to compare patterns of mRNA expression in bovine oocytes matured in vitro in the presence (10%) or absence of fetal calf serum (FCS). Total RNA extracted from matured and denuded oocytes was processed using display Profile kit (Display System Biotech). RFDD RT-PCR products were separated on 6% polyacrylamide gel and analyzed using a Storm 860 scanner. Selected bands representing potentially differentially expressed fragments were excised from the gel and re-amplified. Re-amplified fragments with size matched to the original fragment were cloned into the TA vector and sequenced. Initially, 10 and 15 differentially expressed fragments were isolated from oocytes matured in the presence and absence of FCS, respectively. Eight out of 10 and 10 out of 15 fragments were re-amplified successfully as evidenced by size similarity to the original fragments. Finally, the size of six inserts sequenced from each group matched the size of corresponding original as well as re-amplified fragments. Sequence comparison search revealed similarity of some isolated fragments to 18s ribosomal RNA, bovine apolipoprotein A-I, bovine mitochondrion DNA, human CGI-79 mRNA, human Ab1-interactor protein, and bovine satellite DNA. The other sequenced fragments may represent novel genes. We showed that RFDD RT-PCR can be effectively applied to contrast gene expression pattern in bovine oocytes and that presence or absence of FCS during maturation interval affects gene expression pattern in matured bovine oocytes.

Animals↗
PubMed2001

Production of transgenic bovine embryos by transfer of transfected granulosa cells into enucleated oocytes.

Adult granulosa donor cells used in the nuclear transfer (NT) procedure can result in cloned cattle. Subsequently, it may be possible to use the same cell type to produce cloned transgenic cattle. Therefore, this study examined the effect of genetic manipulation and serum levels in culture of donor granulosa cells on developmental rates and cell number of bovine NT embryos. A primary cell line was established from granulosa cells collected by aspirating ovarian follicles. Cells transfected with a plasmid containing the enhanced green fluorescence protein (EGFP) gene, and non-transfected cells were used for cloning between passage 10 and 15 as serum-starved and serum-fed donor cells. There were no significant differences (P > 0.1) in cleavage rates or development to the blastocyst stage for NT embryos from transfected (60.4 and 13.5%, respectively) or non-transfected (61.9 and 14.1%, respectively) and serum-starved (60.6 and 13.4%, respectively) or serum-fed (61.3 and 14%, respectively) cells. Development rates to blastocyst stage of embryos produced using cells at passage 15 (27.1%) were significantly higher than those produced with cells at passage 10,11, and 13 (7, 11.5, and 14%, respectively, P < 0.05). Green fluorescence was observed at different intensity levels in all blastocyst stage embryos resulting from transfected donor cells. The results of the present study indicated that genetically modified granulosa cells can be used to produce transgenic NT embryos and primary transgenic adult cells at late passage may be more effective donor cells than earlier passaged cells.

Animals↗
PubMed2001

Multiple virulence factors of Cryptococcus neoformans are dependent on VPH1.

Acidification of vesicular compartments plays an important role in a number of cellular transport processes, including protein secretion, metal cofactor insertion, glycosylation and pH stability. In the present study, we identify and characterize a component of the vesicular proton pump, Vph1p, to determine its role in the virulence of the AIDS-related fungal pathogen Cryptococcus neoformans. Insertional mutagenesis and plasmid rescue were used to identify the VPH1 gene by screening for mutants defective in laccase activity. Disruption of VPH1 resulted in defects in three virulence factors (capsule production, laccase and urease expression), as well as a growth defect at 37 degrees C, but only a small growth reduction at 30 degrees C. These effects were duplicated by the vacuolar (H+)-ATPase inhibitor bafilomycin A1. Furthermore, the vph1 insertional mutant was also avirulent in a mouse meningo-encephalitis model. Complementation of the insertional mutant with wild-type VPH1 resulted in a recovery of virulence factor expression, normal growth at 37 degrees C and restoration of full virulence. These studies establish the importance of the VPH1 gene and vesicular acidification in the virulence of C. neoformans.

AIDS-Related Opportunistic Infections↗
PubMed2001

Laccase of Cryptococcus neoformans is a cell wall-associated virulence factor.

Virulence is the outcome of an interaction between the host and a microbe and is characterized by a large array of opposing reactions operating at the host-pathogen interface. Cryptococcus neoformans is an important opportunistic pathogen in immunocompromised patients, including those with human immunodeficiency virus, and expresses a virulence-associated laccase which is believed to oxidize brain catecholamines and iron as a defense against host immune cells. In the present report, we investigated the cellular location of laccase to understand more fully how it contributes to cryptococcal virulence. A monoclonal antibody to the C. neoformans laccase was generated and used to show localization in the cell walls of representative serotype A (H99) and serotype D (B-3501) strains by immunoelectron microscopy. In addition, confocal microscopy was used to show a peripheral location of green fluorescent protein-tagged laccase expressed in live H99 cells. Biochemical studies showed that laccase could be released from intact cells or cell wall fractions with glucanase enzymes but was retained in the cell wall after sequential extraction with 1 M NaCl, 6 M urea, and 1% sodium dodecyl sulfate. The presence of a hydrolyzable bond linking laccase to the cell wall was suggested by removal of laccase from cell wall preparations after they were boiled in 1% sodium dodecyl sulfate, as was the presence of a disulfide or thioester bond by removal with dithiothreitol or beta-mercaptoethanol. These data show that laccase is present as a tightly associated cell wall enzyme that is readily accessible for interactions with host immune cells.

Animals↗
PubMed2000

Polarization dynamics of solitons in birefringent fibers

We study the dynamics of uniformly polarized pulses in a birefringent optical fiber. By considering the Hamiltonian structure, symmetries, and the momentum map of the underlying equations, we obtain a self-consistent set of equations for the polarization state alone. In the autonomous case, we find the bifurcation curve of this system, and discuss how the orbits change in the neighborhood of this curve. We calculate the orbits explicitly. An extension to nonautonomous underlying equations is also possible. We further briefly discuss the effect of radiation emission from solitons as their polarization state changes.

Journal Article↗
PubMed1999

Blue light-directed destabilization of the pea Lhcb1*4 transcript depends on sequences within the 5' untranslated region.

Pea seedlings grown in continuous red light accumulate significant levels of Lhcb1 RNA. When treated with a single pulse of blue light with a total fluence >10(4) micromol m(-2), the rate of Lhcb1 transcription is increased, whereas the level of Lhcb1 RNA is unchanged from that in control seedlings. This RNA destabilization response occurs in developing leaves but not in the apical bud. The data presented here indicate that the same response occurs in the cotyledons of etiolated Arabidopsis seedlings. The blue light-induced destabilization response persists in long hypocotyl hy4 and phytochrome phyA, phyB, and hy1 mutants as well as in far-red light-grown seedlings, indicating that neither CRY1 (encoded by the hy4 locus) nor phytochrome is the sole photoreceptor. Studies with transgenic plants indicate that the destabilization element in the pea Lhcb1*4 transcript resides completely in the 5' untranslated region.

5' Untranslated Regions↗
PubMed1997

Development of a cell line from skin of goldfish, Carassius auratus, and effects of ascorbic acid on collagen deposition.

Growth characteristics and collagen expression were investigated in GFSk-S1, a cell line derived from the skin of an adult goldfish (Carassius auratus). These cells are anchorage dependent, grow well in Leibovitz-15 medium with 10% fetal bovine serum, and have been subcultured routinely for 5 years. Cells at various passages have been successfully cryopreserved and thawed. GFSk-S1 cells show mainly a fibroblastic morphology at low density, but at confluence islands of epithelial-shaped cells appear among the fibroblastic cells. The cells require little maintenance, and cultures have been kept viable for more than 3 months without medium changes. Although best growth was observed at room temperature, cell proliferation still occurred at 28 degrees C, and a subline was maintained and passaged for over a year at 25 degrees C. Cells were exposed to various concentrations of ascorbic acid, and its effects on collagen secretion were monitored by light and electron microscopy. Under phase-contrast microscopy, confluent GFSk-S1 cells exposed to ascorbic acid at 50 micrograms/ml showed distinct development of fibres as early as 3 days after treatment. Histochemical staining for collagen demonstrated a thick network of fibres under a monolayer of ascorbic acid-treated GFSk-S1 cells, and observation by transmission electron microscopy showed collagen fibres with typical banding pattern. This cell line appears to show a stable genotype, as collagen expression was induced at all passages. GFSk-S1 could be useful for studies not only of regulation of protein synthesis, but also of cell differentiation and wound healing.

Animals↗
PubMed1996

A simple near-patient test for nicotine and its metabolites in urine to assess smoking habit.

We describe a disposable, near-patient urine test to monitor cigarette smoking. A plastic device contains the sealed dried reagents to measure nicotine and its metabolites, by a colorimetric assay. The device can be used to give a qualitative assessment of tobacco consumption, simply by observing a colour change. Alternatively, the test can be quantified by measuring the light absorbance with a simple colorimeter, and a concentration of nicotinic metabolites obtained with reference to a cotinine standard. A correction factor for the concentration of the urine sample, based on light absorbance, allows the result to be expressed as a ratio to urine concentration. This method correlates with reported daily cigarette consumption (r = 0.69, p < 0.0001) and compares favourably with cotinine, as measured by gas chromatography (r = 0.89, p < 0.0001). The method provides a simple-to-use, inexpensive way to monitoring tobacco consumption in extralaboratory situations.

Chromatography, Gas↗
PubMed1996

Services for adults who have experienced child sexual assault: improving agency response.

Adults who experienced child sexual assault are likely to be present in all parts of the health and welfare systems both as clients and as staff. Research studies and accounts by survivors indicate that their experiences of seeking help are often not positive. In failing to acknowledge and deal with the issue of childhood sexual assault for adult clients and to be aware of its correlation with current problems, the health and welfare system reflects the larger society by avoiding knowledge of the impact of violence and abuse on health and well-being. This paper begins with an overview of studies on the prevalence of childhood sexual assault in adult populations and in clinical populations and of literature on the long term consequences of child sexual assault. It goes on to consider, with particular reference to an Australian context, how service providers can respond to the needs of survivors within their own agencies and notes the resources they may need to do this well.

Adolescent↗
PubMed1995

Determination of aluminium in serum, dialysate fluid and water by inductively coupled plasma optical emission spectrometry.

Methods for the determination of aluminium in serum, dialysate fluid and water by inductively coupled plasma optical emission spectrometry are described and validated. Aluminium was measured at 167 nm using an argon purged monochromator. Matrix effects in serum and dialysate fluid were overcome by using an yttrium internal standard. Serum was found to have a complicated background in the region of 167 nm: careful selection of the wavelength used for background correction is therefore a pre-requisite for accurate analysis. The method for serum was validated by comparison with electrothermal atomization atomic spectrometry and the limit of agreement determined to be +/- 0.3 mumol/L. Routine performance in a quality assessment scheme has been highly satisfactory for a period of 1 year. The method is ideal for fast and accurate monitoring of patients potentially at risk from aluminium toxicity.

Aluminum↗
PubMed1994

Trends in survival among persons with acquired immunodeficiency syndrome in New York City. The experience of the first decade of the epidemic.

This study examined survival trends among the 23,324 cases of acquired immunodeficiency syndrome (AIDS) meeting the Centers for Disease Control (CDC) definition that were diagnosed and reported to the New York City Department of Health from the beginning of the epidemic in 1980 through June 1989. The survival patterns of 20,760 individuals who survived for at least 1 calendar month beyond diagnosis were analyzed; all survival analyses were truncated at December 1, 1990, 17 months after the last diagnosis. Persons who died during the same month in which they were diagnosed ("zero" survivors) were excluded. Cases were examined by race/ethnicity, sex, age at diagnosis, calendar period of diagnosis, transmission category, CDC AIDS case definition (prior to and after the 1987 change in the AIDS case definition), and nature of diagnosis. Results of two- and three-way categorical analysis and logistic regression analysis are reported. Overall median survival time was 13.7 months (14.0 for males and 12.0 for females). Survival was better for whites than for blacks and Hispanics and was better for men who had sex with men than for injecting drug users. Each of the seven demographic and risk behavior factors was independently associated with survival. Trends in survival during three time periods indicated that survival is improving among all groups examined.

Acquired Immunodeficiency Syndrome↗
PubMed1993

3H-GABA administration during tail regeneration of lizards and autoradiographical localization.

Thirteen lizards (Anolis carolinensis and Scincella lateralis) were injected with 3H-GABA (tritiated gamma-aminobutyric acid) in order to study its localization inside the regenerating tail spinal cord (SC) by means of light and electron microscopic autoradiography. One and three hours after intraperitoneal injection, the radioactivity was essentially localized in regenerating nerves and pale cells, mostly contacting the central canal of the SC as typical Cerebrospinal-Fluid-Contacting-Neurons (CSFCNs). A smaller number of pale cells did not take up 3H-GABA and some of them appeared to be degenerating. Weaker radioactivity in regenerating SC was observed 6 hours post injection. Among non neural tissues, cells of the regenerating blastema, of the meninges and capillaries surrounding the regenerating SC, showed lower 3H-GABA uptake. This indicates that a certain amount of injected 3H-GABA has been converted to other metabolites. No 3H-GABA uptake was detected 1 or 6 hours post injection in normal SC and brain both in grey and white matter. This research indicates that CSFCNs of the regenerating tail in lizards uptake the aminoacid GABA or derived aminoacids, suggesting these cells subserve a high metabolic activity and may be GABA-ergic

Animals↗