Impact of IUdR on Rat 9L glioma cell survival for 25-35 keV photon-activated auger electron therapy.

The goal of the current study was to measure the energy dependence of survival of rat 9L glioma cells labeled with iododeoxyuridine (IUdR) that underwent photon-activated Auger electron therapy using 25-35 keV monochromatic X rays, i.e., above and below the K-edge energy of iodine.

Catalase abrogates β-lapachone-induced PARP1 hyperactivation-directed programmed necrosis in NQO1-positive breast cancers.

Improving patient outcome by personalized therapy involves a thorough understanding of an agent's mechanism of action. β-Lapachone (clinical forms, Arq501/Arq761) has been developed to exploit dramatic cancer-specific elevations in the phase II detoxifying enzyme NAD(P)H:quinone oxidoreductase (NQO1). NQO1 is dramatically elevated in solid cancers, including primary and metastatic [e.

Dependence of cell survival on iododeoxyuridine concentration in 35-keV photon-activated Auger electron radiotherapy.

Purpose: To measure and compare Chinese hamster ovary cell survival curves using monochromatic 35-keV photons and 4-MV x-rays as a function of concentration of the radiosensitizer iododeoxyuridine (IUdR).

Methods And Materials: IUdR was incorporated into Chinese hamster ovary cell DNA at 16.6 ± 1.

Oxidative phosphorylation analysis: assessing the integrated functional activity of human skeletal muscle mitochondria--case studies.

Oxidative phosphorylation analysis, performed on freshly-isolated mitochondria, assesses the integrated function of the electron transport chain (ETC) coupled to ATP synthesis, membrane transport, dehydrogenase activities, and the structural integrity of the mitochondria. In this review, a case study approach is employed to highlight detection of defects in the adenine nucleotide translocator, the pyruvate dehydrogenase complex, fumarase, coenzyme Q function, fatty acid metabolism, and mitochondrial membrane integrity. Our approach uses the substrates glutamate, pyruvate, 2-ketoglutarate (coupled with malonate), malate, and fatty acid substrates (palmitoylcarnitine, octanoylcarnitine, palmitoyl-CoA (with carnitine), octanoyl-CoA (with carnitine), octanoate and acetylcarnitine) in addition to succinate, durohydroquinone and TMPD/ascorbate to uncover metabolic defects that would not be apparent from ETC assays performed on detergent-solubilized mitochondria.

Autosomal dominant acute necrotizing encephalopathy.

Objective: To define the clinical and biochemical abnormalities of an autosomal dominant form of acute encephalopathy.

Methods: The clinical details of 11 affected family members in comparison with 63 unaffected relatives were analyzed.

Results: Affected children become comatose after onset of a febrile illness.

The peripheral benzodiazepine receptor in photodynamic therapy with the phthalocyanine photosensitizer Pc 4.

The peripheral benzodiazepine receptor (PBR) is an 18 kDa protein of the outer mitochondrial membrane that interacts with the voltage-dependent anion channel and may participate in formation of the permeability transition pore. The physiological role of PBR is reflected in the high-affinity binding of endogenous ligands that are metabolites of both cholesterol and heme. Certain porphyrin precursors of heme can be photosensitizers for photodynamic therapy (PDT), which depends on visible light activation of porphyrin-related macrocycles.

beta-Lapachone-induced apoptosis in human prostate cancer cells: involvement of NQO1/xip3.

beta-Lapachone (beta-lap) induces apoptosis in various cancer cells, and its intracellular target has recently been elucidated in breast cancer cells. Here we show that NAD(P)H:quinone oxidoreductase (NQO1/xip3) expression in human prostate cancer cells is a key determinant for apoptosis and lethality after beta-lap exposures. beta-Lap-treated, NQO1-deficient LNCaP cells were significantly more resistant to apoptosis than NQO1-expressing DU-145 or PC-3 cells after drug exposures.

NAD(P)H:Quinone oxidoreductase activity is the principal determinant of beta-lapachone cytotoxicity.

beta-Lapachone activates a novel apoptotic response in a number of cell lines. We demonstrate that the enzyme NAD(P)H:quinone oxidoreductase (NQO1) substantially enhances the toxicity of beta-lapachone. NQO1 expression directly correlated with sensitivity to a 4-h pulse of beta-lapachone in a panel of breast cancer cell lines, and the NQO1 inhibitor, dicoumarol, significantly protected NQO1-expressing cells from all aspects of beta-lapachone toxicity.

MRI-guided radiofrequency thermal ablation of implanted VX2 liver tumors in a rabbit model: demonstration of feasibility at 0.2 T.

Successful radiofrequency (RF) thermal ablation was performed on VX2 tumors implanted in 23 rabbit livers under magnetic resonance (MR) guidance using a C-arm-shaped low-field 0.2 T system. RF application and immediate postprocedure MRI of all animals was performed [T2-weighted, turbo short tau inversion recovery (STIR), T1-weighted before and after gadopentetate dimeglumine administration).

Photodynamic therapy-induced apoptosis in lymphoma cells: translocation of cytochrome c causes inhibition of respiration as well as caspase activation.

L5178Y-R mouse lymphoma (LY-R) cells undergo rapid apoptosis when treated with photodynamic therapy (PDT) sensitized with the silicon phthalocyanine Pc 4. In this study we show that cytochrome c is released into the cytosol within 10 min of an LD99.9 dose of PDT.

Liver biopsy: effects of biopsy needle caliber on bleeding and tissue recovery.

Purpose: To evaluate different-caliber biopsy cutting needles in terms of the benefits and potential risk of bleeding in a swine model.

Materials And Methods: A total of 190 sequential liver biopsy specimens were obtained in 11 Yorkshire pigs (weight, 50-70 lb [22.5-31.

Reduction of intracellular pH is not the mechanism for the synergistic interaction between photodynamic therapy and nigericin.

Previous studies showed that photodynamic therapy (PDT) sensitized by aluminum phthalocyanine can be dramatically potentiated by the K+/H+ ionophore nigericin. Nigericin equilibrates intracellular pH (pHi) and extracellular pH (pHe) and is most effective in potentiating PDT damage when cells are in an acidic environment (pH 6.5-6.

Insulin and insulin-like growth factor-1 (IGF-1) inhibit repair of potentially lethal radiation damage and chromosome aberrations and alter DNA repair kinetics in plateau-phase A549 cells.

Plateau-phase A549 cells exhibit a high capacity for repair of potentially lethal radiation damage (PLD) when allowed to recover in their own spent medium. Addition of either insulin or insulin-like growth factor-1 (IGF-1) to the spent medium 60 to 120 min before irradiation significantly inhibits PLD repair. The 9-h recovery factor (survival with holding/survival without holding) is reduced from 10.

Elevation of GRP-78 and loss of HSP-70 following photodynamic treatment of V79 cells: sensitization by nigericin.

Chinese hamster V79 cells were treated with photodynamic therapy (PDT) sensitized by aluminum phthalocyanine (AlPc) or with the ionophore nigericin or with combinations of PDT and nigericin. We previously showed that PDT and nigericin interact synergistically in the killing of these cells; i.e.

Combined depletion of O6-alkylguanine-DNA alkyltransferase and glutathione to modulate nitrosourea resistance in breast cancer.

MCF-7 human breast cancer cells possess high levels of O6-alkylguanine-DNA alkyltransferase and moderate levels of glutathione, and are more resistant to chloroethylnitrosoureas (CNUs) than cells with low levels of either molecule. The role of each as a component of CNU resistance was assessed using O6-benzylguanine (O6-bG) or O6-methylguanine (O6-mG) to deplete the alkyltransferase and L-buthionine sulfoxamine (L-BSO) to deplete glutathione. O6-bG and O6-mG potentiated 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) cytotoxicity, resulting in a dose modification factor of 5.

Effects of extracellular and intracellular pH on repair of potentially lethal damage, chromosome aberrations and DNA double-strand breaks in irradiated plateau-phase A549 cells.

Plateau-phase A549 cells exhibit a high capacity for repair of potentially lethal radiation damage (PLD). Previously it was found that PLD repair could be partially inhibited by increasing the extracellular pH (pHe) of the spent medium from its normal value of 6.7-6.

Effect of the K+/H+ ionophore nigericin on response of A549 cells to photodynamic therapy and tert-butylhydroperoxide.

The K+/H+ ionophore nigericin dramatically increases killing of V79 cells and A549 cells by photodynamic therapy (PDT) sensitized by chloroaluminum phthalocyanine. Previous studies suggested that the interaction between PDT and nigericin is related to the ability of this ionophore to reduce intracellular pH (pHi). The present study was undertaken to test the possibility that nigericin, by lowering pHi, inhibits reductive detoxification of PDT-produced peroxides by enzymes of the glutathione (GSH) redox cycle and the pentose cycle.

Sensitivity to chemical oxidants and radiation in CHO cell lines deficient in oxidative pentose cycle activity.

In this paper we examine the susceptibility of a series of G6PD- CHO cell lines to a variety of chemical oxidants. Addition of these drugs to K1D, the parental cell line, results in as much as a 20-fold increase in pentose cycle (PC) activity over control values. In two of our mutant lines, E16 and E48, little or no stimulation of PC activity is seen.

Mutagenicity of 2-amino-N6-hydroxyadenine at the tk locus in L5178Y strains differing in repair capabilities and karyotype.

The cytotoxicity and mutagenicity of 2-amino-N6-hydroxyadenine (AHA) were measured in strains of L5178Y differing in repair capabilities and karyotype. Strain LY-R83 is monosomic for chromosome 11 and is therefore hemizygous for the tk gene, while strains LY-R16 and LY-S1 are TK+/- heterozygotes. Both strain LY-R83 and LY-R16 are sensitive to UV light and are presumed to be deficient in the excision of pyrimidine dimers as shown for the parental strain, LY-R (Hagen et al.

Inhibition of recovery from potentially lethal radiation damage in A549 cells by the K+/H+ ionophore nigericin.

A549 cells held for 4 hr in Hank's balanced salt solution, after 10 Gy irradiation, exhibit potentially lethal damage recovery (PLDR) which is dependent on extracellular pH (pHe). Recovery factors of 2.2 to 3.

Enhancement of photodynamic cell killing (with chloroaluminum phthalocyanine) by treatment of V79 cells with the ionophore nigericin.

The K+/H+ ionophore nigericin dramatically increases killing of V79 cells by photodynamic therapy (PDT), when cells pretreated with 1 microM chloroaluminum phthalocyanine are incubated with nigericin before exposure to red light. Nigericin affects primarily the shoulder of the PDT dose-response curve, reducing the surviving fraction from 0.90 to 0.

Role of glutathione in the aerobic radiation response.

We will review the relationships between glutathione (GSH), protein thiols, and cellular responses to radiation, peroxides, and peroxide-producing drugs. Our primary interest involves the behavior of sulfhydryls as electron and hydrogen carriers, and their capacity to protect various target molecules against radiation and peroxidative damage. We used reagents such as L-buthionine sulfoximine (LBSO), alone and in combination with N-ethyl maleimide (NEM), diamide, and dimethylfumarate, to decrease GSH so that it could no longer participate in the electron transfer reactions.

pH-dependent effects of the ionophore nigericin on response of mammalian cells to radiation and heat treatment.

The extracellular pH (pHe) in many solid tumors is often lower than the pH of normal tissues. The K+/H+ ionophore nigericin is toxic to CHO cells when pHe is below but not above 6.5, and thus it has potential for selective killing of tumor cells in an acidic environment.