PubMed Health⌕ Search

Biomedical subjects

T R Barrette

Publications and source records attributed to T R Barrette.

8 recordsLinked to original sources
PubMed2001

Profiling of cancer cells using protein microarrays: discovery of novel radiation-regulated proteins.

The advent of DNA microarray technology will likely have a major impact on the molecular classification and understanding of human cancer. Obtaining a global perspective of proteins expressed in cancer cells is considerably more challenging. Here we describe a microarray-based platform that can be used to measure protein levels and activities in a complex biological milieu such as a cellular lysate. Using a protein microarray made up of 1920 elements (146 distinct antibodies) we were able to monitor alterations of protein levels in LoVo colon carcinoma cells treated with ionizing radiation. The protein microarray approach revealed radiation-induced up-regulation of apoptotic regulators including p53, DNA fragmentation factor 40/caspase activated DNase, DNA fragmentation factor 45/inhibitor of caspase activated DNase, tumor necrosis factor-related apoptosis-inducing ligand, death receptor 5, decoy receptor 2, FLICE-like inhibitory protein, signal transducers and activators of transcription 1alpha, and uncoupling protein 2, among others. Consistent with this observation, an increased percentage of apoptosis was observed in irradiated LoVo cells. Interestingly, we also observed radiation-induced down-regulation of carcinoembryonic antigen, a prototypic cancer biomarker. Selected proteins assessed by microarray were validated by traditional immunoblotting. Taken together, our work suggests that protein/antibody microarrays will facilitate high-throughput proteomic studies of human cancer and carcinogenesis.

Antibodies, Neoplasm↗
PubMed2001

Delineation of prognostic biomarkers in prostate cancer.

Prostate cancer is the most frequently diagnosed cancer in American men. Screening for prostate-specific antigen (PSA) has led to earlier detection of prostate cancer, but elevated serum PSA levels may be present in non-malignant conditions such as benign prostatic hyperlasia (BPH). Characterization of gene-expression profiles that molecularly distinguish prostatic neoplasms may identify genes involved in prostate carcinogenesis, elucidate clinical biomarkers, and lead to an improved classification of prostate cancer. Using microarrays of complementary DNA, we examined gene-expression profiles of more than 50 normal and neoplastic prostate specimens and three common prostate-cancer cell lines. Signature expression profiles of normal adjacent prostate (NAP), BPH, localized prostate cancer, and metastatic, hormone-refractory prostate cancer were determined. Here we establish many associations between genes and prostate cancer. We assessed two of these genes-hepsin, a transmembrane serine protease, and pim-1, a serine/threonine kinase-at the protein level using tissue microarrays consisting of over 700 clinically stratified prostate-cancer specimens. Expression of hepsin and pim-1 proteins was significantly correlated with measures of clinical outcome. Thus, the integration of cDNA microarray, high-density tissue microarray, and linked clinical and pathology data is a powerful approach to molecular profiling of human cancer.

Biomarkers, Tumor↗
PubMed2001

Molecular signatures of sepsis: multiorgan gene expression profiles of systemic inflammation.

During sepsis the host's system-wide response to microbial invasion seems dysregulated. Here we explore the diverse multiorgan transcriptional programs activated during systemic inflammation in a cecal ligation/puncture model of sepsis in rats. Using DNA microarrays representing 7398 genes, we examined the temporal sequence of sepsis-induced gene expression patterns in major organ systems including lung, liver, kidney, thymus, spleen, and brain. Although genes known to be associated with systemic inflammation were identified by our global transcript analysis, many genes and expressed sequence tags not previously linked to the septic response were also elucidated. Taken together, our results suggest activation of a highly complex transcriptional response in individual organs of the septic animal. Several overlying themes emerged from our genome-scale analysis that includes 1) the sepsis response elicited gene expression profiles that were either organ-specific, common to more than one organ, or distinctly opposite in some organs; 2) the brain is protected from sepsis-induced gene activation relative to other organs; 3) the thymus and spleen have an interesting cohort of genes with opposing gene expression patterns; 4) genes with proinflammatory effects were often balanced by genes with anti-inflammatory effects (eg, interleukin-1beta/decoy receptor, xanthine oxidase/superoxide dismutase, Ca2+-dependent PLA2/Ca2+-independent PLA2); and 5) differential gene expression was observed in proteins responsible for preventing tissue injury and promoting homeostasis including anti-proteases (TIMP-1, Cpi-26), oxidant neutralizing enzymes (metallothionein), cytokine decoy receptors (interleukin-1RII), and tissue/vascular permeability factors (aquaporin 5, vascular endothelial growth factor). This global perspective of the sepsis response should provide a molecular framework for future research into the pathophysiology of systemic inflammation. Understanding, on a genome scale, how an organism responds to infection, may facilitate the development of enhanced detection and treatment modalities for sepsis.

Animals↗
PubMed1997

Ultrasonographic detection of testicular ischemia in a canine model using phospholipid coated microbubbles (MRX-115).

The purpose of this study was to determine if the sonographic contrast agent MRX-115 could improve the accuracy of Doppler ultrasonographic diagnosis of testicular ischemia. Testicular duplex ultrasonography was performed on six dogs before and after surgical ligation of the testicular artery, and before and after intravenous injection of MRX-115. Six radiologists blinded to experimental conditions rated the testicular blood flow. Receiver operating characteristics curves for conditions with and without administration of contrast agent were compared using Student's t-test for paired observations. Statistically significant differences were found both for the tests viewed individually (P = 0.003) and for the testes in comparison to the contralateral side (P = 0.0001). MRX-115 therefore is found to improve duplex sonographic evaluation of testicular ischemia.

Analysis of Variance↗
PubMed1996

Microbubbles as novel pressure-sensitive MR contrast agents.

Magnetic resonance imaging contrast agents that are sensitive to pressure would be useful for evaluating cardiovascular function. One such potential contrast agent consists of gas-filled liposome microbubbles. The magnetic susceptibility of the microbubbles locally perturb the static magnetic field, which influences the transverse-relaxation properties of the surrounding medium. Changes in the pressure alter the bubble dimensions, which affects the magnetic field perturbations and, hence, the transverse-relaxation. The effect of these microbubbles on the T2 relaxation times of a water-based medium was measured for liposomes filled with different gases-nitrogen, argon, air, oxygen, xenon, neon, perfluoropentane, perfluorobutane, and sulfur hexafluoride. The air-filled, perfluoropentane-filled and the oxygen-filled liposomes demonstrated the largest effect on transverse-relaxation. The influence of pressure on both gradient-echo and spin-echo signal intensities for air-filled microbubbles was also evaluated. Pressure-induced changes in signal intensity were consistently observed for both the spin-echo and gradient-echo pulses sequences.

Contrast Media↗
PubMed1996

Magnetic resonance guidance of percutaneous ethanol injection in liver.

RATIONALE AND OBJECTIVES: Percutaneous ethanol injection (PEI) is used as a form of treatment for cancer, particularly malignant hepatic tumors. Little is known about the intratumoral distributions of ethanol following PEI. We assessed, using magnetic resonance (MR) imaging, the distribution of ethanol in liver and the concentration of ethanol needed to kill tumor cells in vivo. METHODS: MR imaging studies were performed using phantoms of alcohol, ex vivo bovine liver, and healthy human volunteers. A variety of pulse sequences were tested for their ability to maximize the signal intensity from alcohol while minimizing the signal from liver tissues as well as the regions of necrosis following ethanol injection. A cell culture model of in vitro cytotoxicity was developed to predict the target concentration of alcohol necessary for killing tumor cells. RESULTS: At 1.5 T, we found that an inversion-recovery spin-echo sequence using an inversion time of 250 msec and an echo time of 150 msec in combination with water saturation pulses effectively suppressed the tissue water signal from human liver while obtaining a clear signal from the ethanol. The cytotoxicity experiments suggested that a concentration of 20% or more ethanol is sufficient to completely kill all the tumor cells. CONCLUSION: A critical concentration of ethanol (e.g., 10%) is necessary for full tumoricidal effect. MR imaging should be able to determine the volume of distribution and the intratumoral concentrations of ethanol, thus potentially allowing researchers to achieve the requisite concentrations for maximal tumoricidal effects.

Animals↗
PubMed1995

Genetic dissection of carotenoid synthesis in arabidopsis defines plastoquinone as an essential component of phytoene desaturation.

Carotenoids are C40 tetraterpenoids synthesized by nuclear-encoded multienzyme complexes located in the plastids of higher plants. To understand further the components and mechanisms involved in carotenoid synthesis, we screened Arabidopsis for mutations that disrupt this pathway and cause accumulation of biosynthetic intermediates. Here, we report the identification and characterization of two nonallelic albino mutations, pds1 and pds2 (for phytoene desaturation), that are disrupted in phytoene desaturation and as a result accumulate phytoene, the first C40 compound of the pathway. Surprisingly, neither mutation maps to the locus encoding the phytoene desaturase enzyme, indicating that the products of at least three loci are required for phytoene desaturation in higher plants. Because phytoene desaturase catalyzes an oxidation reaction, it has been suggested that components of an electron transport chain may be involved in this reaction. Analysis of pds1 and pds2 shows that both mutants are plastoquinone and tocopherol deficient, in addition to their inability to desaturate phytoene. Separate steps of the plastoquinone/tocopherol biosynthetic pathway are affected by these two mutations. The pds1 mutation affects the enzyme 4-hydroxyphenylpyruvate dioxygenase because it can be rescued by growth on the product but not the substrate of this enzyme, homogentisic acid and 4-hydroxyphenylpyruvate, respectively. The pds2 mutation most likely affects the prenyl/phytyl transferase enzyme of this pathway. Because tocopherol-deficient mutants in the green alga Scenedesmus obliquus can synthesize carotenoids, our findings demonstrate conclusively that plastoquinone is an essential component in carotenoid synthesis. We propose a model for carotenoid synthesis in photosynthetic tissue whereby plastoquinone acts as an intermediate electron carrier between carotenoid desaturases and the photosynthetic electron transport chain.

Arabidopsis↗