Effect Of Deuterium Oxide Research Articles

Effect of Deuterium Oxide on Gene Expression of recA and colD Induced by UV Radiation in Esherichia coli Cells

Effect of Deuterium Oxide on Gene Expression of recA and colD Induced by UV Radiation in Esherichia coli Cells

Deuterium Oxide (D2O) Induces Early Stress Response Gene Expression and Impairs Growth and Metastasis of Experimental Malignant Melanoma.

Simple SummarySystemic administration of deuterium oxide (‘heavy water’) has shown promise in suppressing tumor growth and metastasis in mammalian cancer models, but no detailed molecular studies have revealed specific molecular pathways mediating cancer-cell-directed activities. Here, for the first time, transcriptomic analysis complemented by in vivo efficacy experiments have addressed this unresolved topic.There are two stable isotopes of hydrogen, protium (1H) and deuterium (2H; D). Cellular stress response dysregulation in cancer represents both a major pathological driving force and a promising therapeutic target, but the molecular consequences and potential therapeutic impact of deuterium (2H)-stress on cancer cells remain largely unexplored. We have examined the anti-proliferative and apoptogenic effects of deuterium oxide (D2O; ‘heavy water’) together with stress response gene expression profiling in panels of malignant melanoma (A375V600E, A375NRAS, G361, LOX-IMVI), and pancreatic ductal adenocarcinoma (PANC-1, Capan-2, or MIA PaCa-2) cells with inclusion of human diploid Hs27 skin fibroblasts. Moreover, we have examined the efficacy of D2O-based pharmacological intervention in murine models of human melanoma tumor growth and metastasis. D2O-induction of apoptosis was substantiated by AV-PI flow cytometry, immunodetection of PARP-1, and pro-caspase 3 cleavage, and rescue by pan-caspase inhibition. Differential array analysis revealed early modulation of stress response gene expression in both A375 melanoma and PANC-1 adenocarcinoma cells elicited by D2O (90%; ≤6 h) (upregulated: CDKN1A, DDIT3, EGR1, GADD45A, HMOX1, NFKBIA, or SOD2 (up to 9-fold; p < 0.01)) confirmed by independent RT-qPCR analysis. Immunoblot analysis revealed rapid onset of D2O-induced stress response phospho-protein activation (p-ERK, p-JNK, p-eIF2α, or p-H2AX) or attenuation (p-AKT). Feasibility of D2O-based chemotherapeutic intervention (drinking water (30% w/w)) was demonstrated in a severe combined immunodeficiency (SCID) mouse melanoma metastasis model using luciferase-expressing A375-Luc2 cells. Lung tumor burden (visualized by bioluminescence imaging) was attenuated by D2O, and inhibition of invasiveness was also confirmed in an in vitro Matrigel transwell invasion assay. D2O supplementation also suppressed tumor growth in a murine xenograft model of human melanoma, and median survival was significantly increased without causing adverse effects. These data demonstrate for the first time that systemic D2O administration impairs growth and metastasis of malignant melanoma through the pharmacological induction of deuterium (2H)-stress.

Stability of Tocopherol Homologs in Bulk Oils at 60°C Oxidation and Chlorophyll Photosensitization by the Action of Moisture

AbstractThe effects of deuterium oxide (D2O) on the stability of tocopherol homologs were evaluated in corn oil stored at 60°C or in the process of chlorophyll photosensitization. The degree of oxidation, changes in moisture, and the levels of tocopherol homologs were analyzed. The moisture content in corn oil incubated with deuterium‐free water (H2O) was significantly (P &lt; 0.05) higher than that in corn oil incubated with D2O. The presence of D2O accelerated the rate of lipid oxidation in corn oil, irrespective of whether it has been oxidized at 60°C or has been photosensitized by chlorophyll. After exposure to either of the oxidative stresses, the stability of β + γ‐tocopherols present in corn oil was enhanced in the presence of D2O compared to corn oil incubated in the presence of H2O, or control corn oil without the addition of moisture. However, the stability of α‐tocopherol in corn oil incubated with D2O was significantly lower after oxidation at 60°C compared to the other conditions (P &lt; 0.05), whereas it was significantly higher than under the other conditions after chlorophyll photosensitization (P &lt; 0.05). The moisture and type of oxidative stress, therefore, play important roles in the stability of tocopherol homologs in bulk oils.

Deuterium Oxide Stabilizes the Membrane Structure of Human Erythrocytes under High Pressure

The effect of deuterium oxide (D2O) on the stabilization of membrane structure in human erythrocytes was examined on the basis of hemolysis under high pressure and extraction of cytoskeletal protei...

T1 nuclear magnetic relaxation dispersion of hyperpolarized sodium and cesium hydrogencarbonate-13 C.

In vivo pH mapping in tissue using hyperpolarized hydrogencarbonate-13 C has been proposed as a method to study tumor growth and treatment and other pathological conditions related to pH changes. The finite spin-lattice relaxation times (T1 ) of hyperpolarized media are a significant limiting factor for in vivo imaging. Relaxation times can be measured at standard magnetic fields (1.5T, 3.0T etc.), but no such data are available at low fields, where T1 values can be significantly shorter. This information is required to determine the potential loss of polarization as the agent is dispensed and transported from the polarizer to the MRI scanner. The purpose of this study is to measure T1 dispersion from low to clinical magnetic fields (0.4 mT to 3.0T) of different hyperpolarized hydrogencarbonate formulations previously proposed in the literature for in vivo pH measurements. 13 C-enriched cesium and sodium hydrogencarbonate preparations were hyperpolarized using dynamic nuclear polarization, and the T1 values of different samples were measured at different magnetic field strengths using a fast field-cycling relaxometer and a 3.0T clinical MRI system. The effects of deuterium oxide as a dissolution medium for sodium hydrogencarbonate were also analyzed. This study finds that the cesium formulation has slightly shorter T1 values compared with the sodium preparation. However, the higher solubility of cesium hydrogencarbonate-13 C means it can be polarized at greater concentration, using less trityl radical than sodium hydrogencarbonate-13 C. This study also establishes that the preparation and handling of sodium hydrogencarbonate formulations in relation to cesium hydrogencarbonate is more difficult, due to the higher viscosity and lower achievable concentrations, and that deuterium oxide significantly increases the T1 of sodium hydrogencarbonate solutions. Finally, this work also investigates the influence of pH on the spin-lattice relaxation of cesium hydrogencarbonate-13 C measured over a pH range of 7 to 9 at 0.47T.

The effect of deuterium oxide on the conformational stability and aggregation of bovine serum albumin

Protein aggregation is a significant problem affecting the integrity of proteins, and is a major hindrance to the development of biopharmaceutical products. Deuterium oxide (D2O), widely used in protein characterization studies, has been shown to promote protein aggregation when used as a substitute for water in most buffered protein solutions; however, a few studies have reported minor improvements in melting point temperatures for some proteins. Our study aims to investigate the effect of D2O on protein stability, using bovine serum albumin (BSA) as a model. We performed accelerated stability studies at high temperatures and assessed the physical and conformational stability of BSA using fluorescence spectroscopy, dynamic light scattering (DLS) and size-exclusion high performance liquid chromatography. Our findings reveal that D2O enhances the conformational stability of monomeric BSA, reducing monomer loss and formation of small aggregates at high temperatures. There is also an increase in the formation of larger aggregates probed by thioflavin T (ThT), however, the increase is not considered significant based on DLS results. Our findings demonstrate that exchanging water with D2O can improve the stability of proteins in solution, by maintaining the stability of the monomeric form, which may be beneficial for the long-term storage of some biological products.

Effects of deuterium oxide on formation of volatiles in linoleic acid model systems at different temperatures and oxygen limitation conditions

Effects of 30, 60, and 90 o C treatments and oxygen limitation on formation of volatiles were determined for linoleic acid model systems containing deuterium oxide (D2O) and deuterium free water. The presence of D2O accelerated consumption of headspace oxygen, indicating that the rate of lipid oxidation increased in the presence of D2O. The presence of deuterium in headspace volatiles was indirectly determined based on comparison of the amount of the fragmented mass to charge ratio (m/z) (molecular weight, Mw), which was 73.1/72.1 for d1-pentane/pentane and 125.1/124.1 for d1-2,4 octadienal/2,4 octadienal. The ratio of 73.1/72.1 (m/z) for pentane was significantly (p<0.05) higher for samples containing D2O than for samples containing deuterium free water at 30, 60, and 90 o C. Other volatiles did not follow the same pattern. 2,4-Octadienal in samples under unlimited oxygen conditions confirmed this trend, indicating that water was incorporated into volatiles during oxidation of linoleic acid under these conditions.

Effects of deuterium oxide on cell growth and vesicle speed in RBL-2H3 cells.

For the first time we show the effects of deuterium oxide on cell growth and vesicle transport in rat basophilic leukemia (RBL-2H3) cells. RBL-2H3 cells cultured with 15 moles/L deuterium showed decreased cell growth which was attributed to cells not doubling their DNA content. Experimental observations also showed an increase in vesicle speed for cells cultured in deuterium oxide. This increase in vesicle speed was not observed in deuterium oxide cultures treated with a microtubule-destabilizing drug, suggesting that deuterium oxide affects microtubule-dependent vesicle transport.

Effects of Deuterium Oxide on the Oxidative Stability and Change of Headspace Volatiles of Corn Oil

AbstractEffects of deuterium oxide and deuterium oxide‐free water on the oxidative stability and formation of headspace volatiles were determined for corn oils to evaluate the role of moisture as an active influential factors during lipid oxidation. Mixtures of corn oil and water with different ratios of deuterium oxide were prepared, and the mixtures were stored at 60 °C for 2 days. Headspace oxygen contents, conjugated dienoic acid (CDA) values, and p‐anisidine values (p‐AV) were analyzed as a measure of oxidative stability, and headspace volatiles were analyzed by solid phase microextraction and a gas chromatography mass selective detector to determine the involvement of deuterium in volatiles. Deuterium oxide accelerated the rate of lipid oxidation in corn oil compared to oils with deuterium‐free water based on the results of headspace oxygen content, CDA, p‐AV, and total volatile content. Fragmented mass to charge ratios (m/z) of 73.1/72.1 for d1‐pentane/pentane and 57.0/56.0 for d1‐2‐propenal/2‐propenal from samples containing deuterium oxide were significantly higher than those from deuterium oxide‐free water, implying that moisture participated to form volatiles in corn oil oxidation under air‐tight condition. Deuterium oxide appeared to accelerate the rate of lipid oxidation in corn oils and participated to form volatiles from oils during oxidation.

Quantum dot induced phototransformation of 2,4-dichlorophenol, and its subsequent chemiluminescence reaction

We have studied the CdTe quantum dot-induced phototransformation of 2,4-dichlorophenol (2,4-DCP) and its subsequent chemiluminescence (CL) reaction. Quantum dots (QDs) of different size and capped with thioglycolic acid were prepared and characterized by molecular spectroscopy, X-ray diffraction and transmission electron microscopy. In the presence of QDs, 2,4-DCP is photochemically transformed into a long-living light emitting precursor which can react with N-bromosuccinimide to produce CL with peak wavelengths at 475 and 550 nm. The formation of singlet oxygen during the phototransformation process was confirmed by the enhancement effect of deuterium oxide on the CL reaction and the change in the UV spectrum of a chemical trap. The CL intensity is linearly related to the concentration of 2,4-DCP in the range from 0.36 to 36 μmol L−1, and the detection limit (at 3σ) is 0.13 μmol L−1.

A Membrane Cell for On-line Hydrogen/Deuterium Exchange to Study Protein Folding and Protein-Protein Interactions by Mass Spectrometry

A membrane cell for hydrogen and deuterium exchange on-line with mass spectrometry has been developed to monitor protein-protein interactions and protein conformations. It consists of two channels separated by a semipermeable membrane, where one channel carries the protein sample and the other deuterium oxide. The membrane allows transfer of deuterium oxide into the sample flow. The labeling time is controlled via the flow rate in the sample channel. This cell was validated against three models commonly used in hydrogen-deuterium exchange mass spectrometry: monitoring of folded and unfolded states in a protein, mapping the protein secondary structure at the peptide level, and detection of protein and antibody interactions. The system avoids the conventionally used sample dilution and handling, allowing for potential automation.

(Corrected) Speed effects in gliding motility assays due to surface passivation, water isotope, and osmotic stress.

AbstractThe molecular motor kinesin-1, an ATPase, and the substrate it walks along, microtubules, are vital components of eukaryotic cells. Kinesin converts chemical energy to linear motion as its two motor domains step along microtubules in a process similar to how we walk. Cells create systems of microtubules that direct the motion of kinesin. This directed motion allows kinesin to transport various cargoes inside cells.During the stepping process, the kinesin motor domains bind and unbind from their binding sites on the microtubules. Binding and unbinding rates of biomolecules are highly dependent on hydration and exclusion of water from the binding interface. Osmotic stress will likely strongly affect the binding and unbinding rates for kinesin and thus offers a tool to specifically probe those steps. We will report the effects of different osmolytes on microtubule speed and other observables in the gliding motility assay.Kinesin’s kinetic core cycle hydrolyzes ATP with the help of a water molecule. Any modification to the water molecules the kinesin is in will change how ATP hydrolyzes and will ultimately affect how kinesin moves along microtubules. We will report preliminary results showing how kinesin is affected when the solvent it is in is changed from light water to heavy water.When used in a surface assay or in devices, the kinesin and microtubule system is also dependent on substrate passivation. Kinesin motor domains do not transport microtubules in the gliding motility assay if kinesin is added to a glass microscope slide that has not been functionalized. Functionalization of the glass slides and slips is typically performed with bovine milk proteins called caseins. Bovine casein is a globular protein that can be broken up into four constituents: αs1, αs2, β, and κ. Each casein constituent affects how kinesin adheres to the glass and ultimately the speed at which microtubules are observed to glide at. Building on the work of Verma et.al., we have found that each constituent individually produces different outcomes in gliding assays. We will present these findings and discuss implications they have for the use of gliding assays to study kinesin and the use of the kinesin-microtubule system in microdevices.[1] Chaen, S, N Yamamoto, I Shirakawa, and H Sugi. 2001. Effect of deuterium oxide on actomyosin motility in vitro. Biochimica et biophysica acta 1506, no. 3: 218-23.[2] Vivek Verma, William O Hancock, Jeffrey M Catchmark, "The role of casein in supporting the operation of surface bound kinesin," J. Biol. Eng. 2008; 2: 14. Acknowledgements: This work was supported by the DTRA CB Basic Research Program under Grant No. HDTRA1-09-1-008.CORRECTIONS: At the workshop, Erik Schaffer pointed out to us that some of our speed differences (casein data) were surely due to microscope increasing in temperature. I've edited the poster to correct for this. Thanks, Erik!

Deuteration as a tool in investigating the role of protons in cell signaling

Background The mechanisms underlying the inhibitory effects of deuterium oxide (D 2O; heavy water) are likely to provide insight into the fundamental significance of hydrogen bonds in biological functions. Previously, to begin elucidating the effect of D 2O on physiological functions in living cells, we studied the effects of D 2O on voltage-sensitive Ca 2+ channels in AtT 20 cells and showed that actin distribution, Ca 2+ currents, and β-endorphin release were affected. However, the molecular mechanisms underlying the inhibitory effects of D 2O in whole animals and living cells remain obscure, especially in the effects of D 2O on the cell signaling. Methods We investigated the molecular mechanisms underlying the inhibitory effects of D 2O on the IP 3-mediated Ca 2+ signaling pathway using Ca 2+ imaging and micro-calorimetric measurements in mGluR1-expressing CHO cells. Results DHPG-induced Ca 2+ elevations were markedly reduced in D 2O. Moreover, the Ca 2+ elevations were completely suppressed in H 2O after receptor activation with DHPG in D 2O, recovering gradually in H 2O medium. Without prior stimulation in D 2O, however, DHPG-induced Ca 2+ elevations in H 2O were not affected. Micro-calorimetric measurements showed reduced total DHPG-evoked heat generation in D 2O, while initial heat production and absorption associated with receptor activation were found to be larger. The reduction of DHPG-induced Ca 2+ elevation and heat generation in D 2O medium may be due to decreased amount of IP 3 by the reduced hydrolysis of PIP 2. General significance Protein structure changes due to the replacement of hydrogen with deuterium will induce the inhibitory effects of D 2O by reduction of the frequency of –OH bonds.

(Corrected) Speed effects in gliding motility assays due to surface passivation, water isotope, and osmotic stress.

AbstractThe molecular motor kinesin-1, an ATPase, and the substrate it walks along, microtubules, are vital components of eukaryotic cells. Kinesin converts chemical energy to linear motion as its two motor domains step along microtubules in a process similar to how we walk. Cells create systems of microtubules that direct the motion of kinesin. This directed motion allows kinesin to transport various cargos inside cells.During the stepping process, the kinesin motor domains bind and unbind from their binding sites on the microtubules. Binding and unbinding rates of biomolecules are highly dependent on hydration and exclusion of water from the binding interface. Osmotic stress will likely strongly affect the binding and unbinding rates for kinesin and thus offers a tool to specifically probe those steps. We will report the effects of different osmolytes on microtubule speed and other observables in the gliding motility assay.Kinesin’s kinetic core cycle hydrolyzes ATP with the help of a water molecule. Any modification to the water molecules the kinesin is in will change how ATP hydrolyzes and will ultimately affect how kinesin moves along microtubules. We will report preliminary results showing how kinesin is affected when the solvent it is in is changed from light water to heavy water.When used in a surface assay or in devices, the kinesin and microtubule system is also dependent on substrate passivation. Kinesin motor domains do not transport microtubules in the gliding motility assay if kinesin is added to a glass microscope slide that has not been functionalized. Functionalization of the glass slides and slips is typically performed with bovine milk proteins called caseins. Bovine casein is a globular protein that can be broken up into four constituents: αs1, αs2, β, and κ. Each casein constituent affects how kinesin adheres to the glass and ultimately the speed at which microtubules are observed to glide at. Building on the work of Verma et.al., we have found that each constituent individually produces different outcomes in gliding assays. We will present these findings and discuss implications they have for use of gliding assays to study kinesin and use of kinesin-microtubule system in microdevices.[1] Chaen, S, N Yamamoto, I Shirakawa, and H Sugi. 2001. Effect of deuterium oxide on actomyosin motility in vitro. Biochimica et biophysica acta 1506, no. 3: 218-23.[2] Vivek Verma, William O Hancock, Jeffrey M Catchmark, "The role of casein in supporting the operation of surface bound kinesin," J. Biol. Eng. 2008; 2: 14. Acknowledgements: This work was supported by the DTRA CB Basic Research Program under Grant No. HDTRA1-09-1-008.CORRECTIONS: At the workshop, Erik Schaffer pointed out to us that some of our speed differences (casein data) were surely due to microscope increasing in temperature. I've edited the poster to correct for this. Thanks, Erik!

(Corrected) Speed effects in gliding motility assays due to surface passivation, water isotope, and osmotic stress.

The molecular motor kinesin-1, an ATPase, and the substrate it walks along, microtubules, are vital components of eukaryotic cells. Kinesin converts chemical energy to linear motion as its two motor domains step along microtubules in a process similar to how we walk. Cells create systems of microtubules that direct the motion of kinesin. This directed motion allows kinesin to transport various cargos inside cells.During the stepping process, the kinesin motor domains bind and unbind from their binding sites on the microtubules. Binding and unbinding rates of biomolecules are highly dependent on hydration and exclusion of water from the binding interface. Osmotic stress will likely strongly affect the binding and unbinding rates for kinesin and thus offers a tool to specifically probe those steps. We will report the effects of different osmolytes on microtubule speed and other observables in the gliding motility assay.Kinesin’s kinetic core cycle hydrolyzes ATP with the help of a water molecule. Any modification to the water molecules the kinesin is in will change how ATP hydrolyzes and will ultimately affect how kinesin moves along microtubules. We will report preliminary results showing how kinesin is affected when the solvent it is in is changed from light water to heavy water.When used in a surface assay or in devices, the kinesin and microtubule system is also dependent on substrate passivation. Kinesin motor domains do not transport microtubules in the gliding motility assay if kinesin is added to a glass microscope slide that has not been functionalized. Functionalization of the glass slides and slips is typically performed with bovine milk proteins called caseins. Bovine casein is a globular protein that can be broken up into four constituents: αs1, αs2, β, and κ. Each casein constituent affects how kinesin adheres to the glass and ultimately the speed at which microtubules are observed to glide at. Building on the work of Verma et.al., we have found that each constituent individually produces different outcomes in gliding assays. We will present these findings and discuss implications they have for use of gliding assays to study kinesin and use of kinesin-microtubule system in microdevices.[1] Chaen, S, N Yamamoto, I Shirakawa, and H Sugi. 2001. Effect of deuterium oxide on actomyosin motility in vitro. Biochimica et biophysica acta 1506, no. 3: 218-23.[2] Vivek Verma, William O Hancock, Jeffrey M Catchmark, "The role of casein in supporting the operation of surface bound kinesin," J. Biol. Eng. 2008; 2: 14. This work was supported by the DTRA CB Basic Research Program under Grant No. HDTRA1-09-1-008.CORRECTIONS: At the workshop, Erik Schaffer pointed out to us that some of our speed differences (casein data) were surely due to microscope increasing in temperature. I've edited the poster to correct for this. Thanks, Erik!

Speed effects in gliding motility assays due to surface passivation, water isotope, and osmotic stress.

AbstractThe molecular motor kinesin-1, an ATPase, and the substrate it walks along, microtubules, are vital components of eukaryotic cells. Kinesin converts chemical energy to linear motion as its two motor domains step along microtubules in a process similar to how we walk. Cells create systems of microtubules that direct the motion of kinesin. This directed motion allows kinesin to transport various cargos inside cells.During the stepping process, the kinesin motor domains bind and unbind from their binding sites on the microtubules. Binding and unbinding rates of biomolecules are highly dependent on hydration and exclusion of water from the binding interface. Osmotic stress will likely strongly affect the binding and unbinding rates for kinesin and thus offers a tool to specifically probe those steps. We will report the effects of different osmolytes on microtubule speed and other observables in the gliding motility assay.Kinesin’s kinetic core cycle hydrolyzes ATP with the help of a water molecule. Any modification to the water molecules the kinesin is in will change how ATP hydrolyzes and will ultimately affect how kinesin moves along microtubules. We will report preliminary results showing how kinesin is affected when the solvent it is in is changed from light water to heavy water. When used in a surface assay or in devices, the kinesin and microtubule system is also dependent on substrate passivation. Kinesin motor domains do not transport microtubules in the gliding motility assay if kinesin is added to a glass microscope slide that has not been functionalized. Functionalization of the glass slides and slips is typically performed with bovine milk proteins called caseins. Bovine casein is a globular protein that can be broken up into four constituents: αs1, αs2, β, and κ. Each casein constituent affects how kinesin adheres to the glass and ultimately the speed at which microtubules are observed to glide at. Building on the work of Verma et.al., we have found that each constituent individually produces different outcomes in gliding assays. We will present these findings and discuss implications they have for use of gliding assays to study kinesin and use of kinesin-microtubule system in microdevices. [1] Chaen, S, N Yamamoto, I Shirakawa, and H Sugi. 2001. Effect of deuterium oxide on actomyosin motility in vitro. Biochimica et biophysica acta 1506, no. 3: 218-23. [2] Vivek Verma, William O Hancock, Jeffrey M Catchmark, "The role of casein in supporting the operation of surface bound kinesin," J. Biol. Eng. 2008; 2: 14. Acknowledgements: This work was supported by the DTRA CB Basic Research Program under Grant No. HDTRA1-09-1-008.

The effect of deuterium oxide on the stability of the collagen model peptides H‐(Pro‐Pro‐Gly)10‐OH, H‐(Gly‐Pro‐4(R)Hyp)9‐OH, and Type I collagen

The collagen triple helix has a larger accessible surface area per molecular mass than globular proteins, and therefore potentially more water interaction sites. The effect of deuterium oxide on the stability of collagen model peptides and Type I collagen molecules was analyzed by circular dichroism and differential scanning calorimetry. The transition temperatures (T(m)) of the protonated peptide (Pro-Pro-Gly)(10) were 25.4 and 28.7 degrees C in H(2)O and D(2)O, respectively. The increase of the T(m) of (Pro-Pro-Gly)(10) measured calorimetrically at 1.0 degrees C min(-1) in a low pH solution from the protonated to the deuterated solvent was 5.1 degrees C. The increases of the T(m) for (Gly-Pro-4(R)Hyp)(9) and pepsin-extracted Type I collagen were measured as 4.2 and 2.2 degrees C, respectively. These results indicated that the increase in the T(m) in the presence of D(2)O is comparable to that of globular proteins, and much less than reported previously for collagen model peptides [Gough and Bhatnagar, J Biomol Struct Dyn 1999, 17, 481-491]. These experimental results suggest that the interaction of water molecules with collagen is similar to the interaction of water with globular proteins, when the ratio of collagen to water is very small and collagen is monomerically dispersed in the solvent.

Effects of bromide upon reaction of nucleosides with hydrogen peroxide induced by ultraviolet light

When ultraviolet light was irradiated on a neutral solution of deoxynucleosides and hydrogen peroxide, concentrations of all the deoxynucleosides decreased greatly. Addition of bromide in the system suppressed the reactions of 2′-deoxycytidine, 2′-deoxythymidine, and 2′-deoxyadenosine, but not that of 2′-deoxyguanosine. Addition of hydroxyl radical scavengers suppressed the reaction. The effect of deuterium oxide, an enhancer of singlet oxygen, was small. It is reported that hydroxyl radical, generating from hydrogen peroxide by ultraviolet irradiation, can react with bromide forming bromine radical, and that bromine radical reacts with bromide forming dibromide radical anion. Our result of dose dependency of bromide suggests that dibromide radical anion is the reaction species to react only with 2′-deoxyguanosine.

The effect of deuterium oxide on hydration structure of proteinase K

The effect of deuterium oxide on hydration structure of proteinase K

Synergistic effects of deuterium oxide and gemcitabine in human pancreatic cancer cell lines

Purpose Pancreatic cancer still remains a treatment-refractory cancer. Standard therapy for metastatic cancer is gemcitabine (dFdC) chemotherapy. Since heavy water (deuterium oxide, D 2O) was shown to be active in pancreatic cancer in vitro, we examined the simultaneous or sequential cytotoxic effects of D 2O and dFdC in pancreatic cancer cell lines (AsPC-1, BxPC-3, and PANC-1). Moreover, we investigated the effect of D 2O treatment on the colony formation of peripheral blood mononuclear cells (PBMNC) as well as the apoptosis inducing activity of D 2O and dFdC and the regulation of tumor suppressor gene p21. Results Simultaneous incubation of human pancreatic carcinoma cells with D 2O and dFdC led to a decrease of IC 50 values of dFdC alone in all cell lines examined. Sequential application of D 2O and dFdC caused synergistic effects. Treatment with 10–30% D 2O did not show any significant inhibition effects on the colony formation of peripheral blood mononuclear cells (PBMNC), indicating limited adverse effects of D 2O on bone marrow cells. Treatment with D 2O in combination with dFdC significantly ( p < 0.05) increased the induction of apoptosis in PANC-1 and AsPC-1 cells and led to an overexpression of p21 tumor suppressor gene compared to incubation with dFdC alone. As the combination of D 2O and dFdC might offer an additional option for the control of pancreatic cancer, this treatment should be investigated in a pancreas carcinoma animal model in order to scrutinize the in vitro data.