International Journal of Radiation Oncology Biology Physics, 1992
There is emerging and established clinical and laboratory evidence that proliferation of tumor cl... more There is emerging and established clinical and laboratory evidence that proliferation of tumor clonogens during radiation therapy can impair local tumor control. The pre-treatment, tumor potential doubling time, T(pot), estimated with in situ bromodeoxyuridine (BrdUrd) labeling, followed by a single biopsy and flow cytometry, may be a predictor of a given tumor's ability to undergo such intra-treatment proliferation. Recent studies have found a strong similarity between T(pot)'s determined in this fashion and the effective doubling times of surviving tumor cells during radiotherapy, as estimated from tumor control versus treatment duration data. Furthermore, several preliminary clinical studies have indicated that T(pot) may be a predictor of outcome, with faster tumors doing worse. Accelerated fractionation might overcome such proliferation, but is more acutely toxic and is unlikely to benefit patients with slowly proliferating tumors. Thus, the BrdUrd/single biopsy method may offer the possibility of selecting between accelerated and conventional or hyperfractionated treatment. Several approaches to the analysis of data generated by this method have been described, but there has been little documentation of the validity of methods in experimental systems, particularly in human experimental tumors. This study explores various analytic methods employed with the BrdUrd, delayed, single-biopsy technique used in determining the potential doubling time, T(pot), of tumors. It compares methods of analysis in three experimental systems and in 40 in situ-labeled human tumors, and proposes a method for shortening the required labeling-biopsy interval to a clinically more convenient range of 3 to 4 hours.
In this paper, we report the assembly of single-walled carbon nanotubes (SWNTs) and single-strand... more In this paper, we report the assembly of single-walled carbon nanotubes (SWNTs) and single-stranded DNA to develop a new class of fluorescent biosensors which are able to probe and recognize biomolecular interactions in a homogeneous format. This novel sensing platform consists of a structure formed by the interaction of SWNTs and dye-labeled DNA oligonucleotides such that the proximity of the nanotube to the dye effectively quenches the fluorescence in the absence of a target. Conversely, and very importantly, the competitive binding of a target DNA or protein with SWNTs for the oligonucleotide results in the restoration of fluorescence signal in increments relative to the fluorescence without a target. This signaling mechanism makes it possible to detect the target by fluorescence spectroscopy. In the present study, the schemes for such fluorescence changes were examined by fluorescence anisotropy and fluorescence intensity measurements for DNA hybridization and aptamer-protein interaction studies.
A novel aptamer-based molecular probe design employing intramolecular signal transduction is demo... more A novel aptamer-based molecular probe design employing intramolecular signal transduction is demonstrated. The probe is composed of three elements: an aptamer, a short, partially cDNA sequence, and a PEG linker conjugating the aptamer with the short DNA strand. We have termed this aptamer probe an "aptamer switch probe", or ASP. The ASP design utilizes both a fluorophore and a quencher which are respectively modified at the two termini of the ASP. In the absence of the target molecule, the short DNA will hybridize with the aptamer, keeping the fluorophore and quencher in close proximity, thus switching off the fluorescence. However, when the ASP meets its target, the binding between the aptamer and the target molecule will disturb the intramolecular DNA hybridization, move the quencher away from the fluorophore, and, in effect, switch on the fluorescence. Both ATP and human alpha-thrombin aptamers were engineered to demonstrate this design, and both showed that fluorescence enhancement could be quantitatively mediated by the addition of various amounts of target molecules. Both of these ASPs presented excellent selectivity and prompt response toward their targets. With intrinsic advantages resulting from its intramolecular signal transduction architecture, the ASP design holds promising potential for future applications, such as biochip and in situ imaging, which require reusability, excellent stability, prompt response, and high sensitivity.
Molecular beacons (MBs) are specifically designed DNA hairpin structures that are widely used as ... more Molecular beacons (MBs) are specifically designed DNA hairpin structures that are widely used as fluorescent probes. Applications of MBs range from genetic screening, biosensor development, biochip construction, and the detection of single-nucleotide polymorphisms to mRNA monitoring in living cells. The inherent signal-transduction mechanism of MBs enables the analysis of target oligonucleotides without the separation of unbound probes. The MB stem–loop structure holds the fluorescence-donor and fluorescence-acceptor moieties in close proximity to one another, which results in resonant energy transfer. A spontaneous conformation change occurs upon hybridization to separate the two moieties and restore the fluorescence of the donor. Recent research has focused on the improvement of probe composition, intracellular gene quantitation, protein–DNA interaction studies, and protein recognition.
Purpose Orally administered rutin reportedly ameliorates 2,4,6-trinitrobenzene sulfonic acid (TNB... more Purpose Orally administered rutin reportedly ameliorates 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis of rats. We investigated the metabolic and pharmacological properties of rutin underlying the rutin-mediated amelioration of the rat colitis. Methods Apparent partition coefficients of rutin and its aglycone quercetin were compared. The biochemical/chemical stability of rutin was examined in the contents of various segments of gastrointestinal tracts of rats. Inflammatory indices were determined in the colitis rats after oral administration of rutin or rectal administration of quercetin. In human colon epithelial cells, the effect of quercetin on tumor necrosis factor-alpha (TNF-α)-induced nuclear factor kappa B (NFκB) activation was examined. Results The sugar residue in rutin greatly lowered the apparent partition coefficient and was rapidly deglycosylated to liberate quercetin in the cecal contents, whereas it was stable in the contents of the upper intestine. Not only oral administration of rutin but also rectal administration of quercetin remarkably ameliorated TNBS-induced colitis rats, indicating that quercetin liberated from rutin is therapeutically active. Furthermore, quercetin dose-dependently inhibited an inflammatory signal TNF-α-dependent NFκB activation. Conclusions Our data suggest that rutin acted as a quercetin deliverer to the large intestine and its anti-inflammatory action in TNBS-induced colitis rats may be through quercetin-mediated inhibition of TNF-α-induced NFκB activation.
International Journal of Radiation Oncology Biology Physics, 1992
There is emerging and established clinical and laboratory evidence that proliferation of tumor cl... more There is emerging and established clinical and laboratory evidence that proliferation of tumor clonogens during radiation therapy can impair local tumor control. The pre-treatment, tumor potential doubling time, T(pot), estimated with in situ bromodeoxyuridine (BrdUrd) labeling, followed by a single biopsy and flow cytometry, may be a predictor of a given tumor's ability to undergo such intra-treatment proliferation. Recent studies have found a strong similarity between T(pot)'s determined in this fashion and the effective doubling times of surviving tumor cells during radiotherapy, as estimated from tumor control versus treatment duration data. Furthermore, several preliminary clinical studies have indicated that T(pot) may be a predictor of outcome, with faster tumors doing worse. Accelerated fractionation might overcome such proliferation, but is more acutely toxic and is unlikely to benefit patients with slowly proliferating tumors. Thus, the BrdUrd/single biopsy method may offer the possibility of selecting between accelerated and conventional or hyperfractionated treatment. Several approaches to the analysis of data generated by this method have been described, but there has been little documentation of the validity of methods in experimental systems, particularly in human experimental tumors. This study explores various analytic methods employed with the BrdUrd, delayed, single-biopsy technique used in determining the potential doubling time, T(pot), of tumors. It compares methods of analysis in three experimental systems and in 40 in situ-labeled human tumors, and proposes a method for shortening the required labeling-biopsy interval to a clinically more convenient range of 3 to 4 hours.
In this paper, we report the assembly of single-walled carbon nanotubes (SWNTs) and single-strand... more In this paper, we report the assembly of single-walled carbon nanotubes (SWNTs) and single-stranded DNA to develop a new class of fluorescent biosensors which are able to probe and recognize biomolecular interactions in a homogeneous format. This novel sensing platform consists of a structure formed by the interaction of SWNTs and dye-labeled DNA oligonucleotides such that the proximity of the nanotube to the dye effectively quenches the fluorescence in the absence of a target. Conversely, and very importantly, the competitive binding of a target DNA or protein with SWNTs for the oligonucleotide results in the restoration of fluorescence signal in increments relative to the fluorescence without a target. This signaling mechanism makes it possible to detect the target by fluorescence spectroscopy. In the present study, the schemes for such fluorescence changes were examined by fluorescence anisotropy and fluorescence intensity measurements for DNA hybridization and aptamer-protein interaction studies.
A novel aptamer-based molecular probe design employing intramolecular signal transduction is demo... more A novel aptamer-based molecular probe design employing intramolecular signal transduction is demonstrated. The probe is composed of three elements: an aptamer, a short, partially cDNA sequence, and a PEG linker conjugating the aptamer with the short DNA strand. We have termed this aptamer probe an "aptamer switch probe", or ASP. The ASP design utilizes both a fluorophore and a quencher which are respectively modified at the two termini of the ASP. In the absence of the target molecule, the short DNA will hybridize with the aptamer, keeping the fluorophore and quencher in close proximity, thus switching off the fluorescence. However, when the ASP meets its target, the binding between the aptamer and the target molecule will disturb the intramolecular DNA hybridization, move the quencher away from the fluorophore, and, in effect, switch on the fluorescence. Both ATP and human alpha-thrombin aptamers were engineered to demonstrate this design, and both showed that fluorescence enhancement could be quantitatively mediated by the addition of various amounts of target molecules. Both of these ASPs presented excellent selectivity and prompt response toward their targets. With intrinsic advantages resulting from its intramolecular signal transduction architecture, the ASP design holds promising potential for future applications, such as biochip and in situ imaging, which require reusability, excellent stability, prompt response, and high sensitivity.
Molecular beacons (MBs) are specifically designed DNA hairpin structures that are widely used as ... more Molecular beacons (MBs) are specifically designed DNA hairpin structures that are widely used as fluorescent probes. Applications of MBs range from genetic screening, biosensor development, biochip construction, and the detection of single-nucleotide polymorphisms to mRNA monitoring in living cells. The inherent signal-transduction mechanism of MBs enables the analysis of target oligonucleotides without the separation of unbound probes. The MB stem–loop structure holds the fluorescence-donor and fluorescence-acceptor moieties in close proximity to one another, which results in resonant energy transfer. A spontaneous conformation change occurs upon hybridization to separate the two moieties and restore the fluorescence of the donor. Recent research has focused on the improvement of probe composition, intracellular gene quantitation, protein–DNA interaction studies, and protein recognition.
Purpose Orally administered rutin reportedly ameliorates 2,4,6-trinitrobenzene sulfonic acid (TNB... more Purpose Orally administered rutin reportedly ameliorates 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis of rats. We investigated the metabolic and pharmacological properties of rutin underlying the rutin-mediated amelioration of the rat colitis. Methods Apparent partition coefficients of rutin and its aglycone quercetin were compared. The biochemical/chemical stability of rutin was examined in the contents of various segments of gastrointestinal tracts of rats. Inflammatory indices were determined in the colitis rats after oral administration of rutin or rectal administration of quercetin. In human colon epithelial cells, the effect of quercetin on tumor necrosis factor-alpha (TNF-α)-induced nuclear factor kappa B (NFκB) activation was examined. Results The sugar residue in rutin greatly lowered the apparent partition coefficient and was rapidly deglycosylated to liberate quercetin in the cecal contents, whereas it was stable in the contents of the upper intestine. Not only oral administration of rutin but also rectal administration of quercetin remarkably ameliorated TNBS-induced colitis rats, indicating that quercetin liberated from rutin is therapeutically active. Furthermore, quercetin dose-dependently inhibited an inflammatory signal TNF-α-dependent NFκB activation. Conclusions Our data suggest that rutin acted as a quercetin deliverer to the large intestine and its anti-inflammatory action in TNBS-induced colitis rats may be through quercetin-mediated inhibition of TNF-α-induced NFκB activation.
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