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Moisture variation has been noted as a driver of strains in both natural and anthropogenic bedrock environments. Similarly, increasing water content has been shown to reduce elastic stiffness in a variety of rock materials, though evidence for granites is limited. This study presents strains of an axially stressed (0.1 MPa) Herrnholz granite cylinder with ambient relative humidity alternating between 20% and 90% in a stepwise manner. At each ambient humidity level, the Young's modulus and Poisson's ratio were determined by performing a series of load and unload cycles at 1–12 hr intervals. We observed that when the ambient humidity increased from 20% to 90%, Young's modulus declined by 13% on average, and nearly returned to the initial dry value when the ambient humidity was reduced to 20%. Poisson's ratio increased by 130% in response to the same humidity change, and approximately 60% of it was reversed when dried. These changes occurred linearly with a volumetric strain of up to 8 × 10−4 of the tested sample, equivalent to 24.5 MPa internal stress. This stress change is attributed to the generation of nanoscale adsorption stress, which includes surface adhesion pressure along pore walls and capillary pressures within characteristic pore spaces. Using a modified adsorption model, the two contributions were estimated to be 8.5 and 16 MPa, respectively. The agreement between laboratory-derived and modeled stress change validates the proposed mechanism of adsorption-induced strains and elastic property variations in unweathered granite., Journal of Geophysical Research: Solid Earth, 127 (11), ISSN:2169-9313, ISSN:0148-0227, ISSN:2169-9356

NQO1 (NAD(P)H:quinoneoxidoreductase 1) is a reductive enzyme that is an important activator of bioreductive antitumor agents. NQO1 activity varies in individual tumors but is generally higher in tumor cells than in normal cells. NQO1 has been used as a target for tumor specific drug development. We investigated a series of bioreductive benzoquinone mustard analogs as a model for NQO1 targeted individualized cancer chemotherapy. We compared the tumor cell growth inhibitory activity of benzoquinone mustard analogs with sterically bulky groups of different size and placed at different positions on the benzoquinone ring, using tumor cell lines with different levels of NQO1. We demonstrated that functional groups of different steric size could be used to produce a series of bioreductive antitumor agents that were activated by different levels of NQO1 in tumor cells. This series of drugs could then be used to target cells with specific levels of NQO1 for growth inhibition and to avoid damage to normal cells, like bone marrow cells, that have low levels of NQO1. This approach could be used to develop new bioreductive antitumor agents for NQO1 targeted individualized cancer chemotherapy.

RH1 is a new bioreductive agent that is an excellent substrate for the two-electron reducing enzyme, NAD(P)H quinone oxidoreductase 1 (NQO1). RH1 may be an effective NQO1-directed antitumor agent for treatment of cancer cells having elevated NQO1 activity. As some studies have indicated that RH1 may also be a substrate for the one-electron reducing enzyme, NADPH cytochrome P450 reductase (P450 Red), P450 Red may contribute to the activation of RH1 where NQO1 activities are low and P450 Red activities are high. The mean P450 Red activity in the human tumor cell line panel used by NCI for evaluation of new anticancer agents is 14.8 nmol min(-1) mg prot(-1), while the mean NQO1 activity in these cell lines is 199.5 nmol min(-1) mg prot(-1). Thus, we investigated whether P450 Red could play a role in activating RH1.Reduction of RH1 by purified human P450 Red was investigated using electron paramagnetic resonance and spectroscopic assays. The ability of RH1 to produce DNA damage following reduction by P450 Red was studied using gel assays. To determine the role of P450 Red in activation of RH1 in cells, cell growth inhibition studies with inhibitors of P450 Red and NQO1 were carried out in T47D human breast cancer cells and T47D cells transfected with the human P450 Red gene (T47D-P450) that have P450 Red activities of 11.5 and 311.8 nmol min(-1) mg prot(-1), respectively.Reduction studies using purified P450 Red and NQO1 confirmed that RH1 can be reduced by both enzymes, but redox cycling was slower following reduction by NQO1. RH1 produced DNA strand breaks and crosslinks in isolated DNA after reduction by either P450 Red or NQO1. DPIC, an inhibitor of P450 Red, had no effect on cell growth inhibition by RH1 in T47D cells, and had only a small effect on cell growth inhibition by RH1 in the presence of the NQO1 inhibitor, dicoumarol, in T47D-P450 cells.These results demonstrated that P450 Red does not contribute to the activation of RH1 in cells with normal P450 Red activity and plays only a minor role in activating this agent in cells with high levels of this enzyme. These studies confirmed that P450 Red could activate RH1 and provided the first direct evidence that RH1 could produce both DNA strand breaks and DNA crosslinks after reduction by P450 Red. However, the results strongly suggest that P450 Red does not play a significant role in activating RH1 in cells with normal P450 Red activity.

NQO1 is a reductive enzyme that is important for the activation of many bioreductive agents and is a target for an enzyme-directed approach to cancer therapy. It can be selectively induced in many tumor types by a number of compounds including dimethyl fumarate and sulforaphane. Mitomycin C is a bioreductive agent that is used clinically for treatment of solid tumors. RH1 (2,5-diaziridinyl-3-(hydroxymethyl)- 6-methyl-1,4-benzoquinone) is a new bioreductive agent currently in clinical trials. We have shown previously that induction of NQO1 can enhance the antitumor activity of mitomycin C in tumor cells in vitro and in vivo. As RH1 is activated selectively by NQO1 while mitomycin C is activated by many reductive enzymes, we investigated whether induction of NQO1 would produce a greater enhancement of the antitumor activity of RH1 compared with mitomycin C. HCT116 human colon cancer cells and T47D human breast cancer cells were incubated with or without dimethyl fumarate or sulforaphane followed by mitomycin C or RH1 treatment, and cytotoxic activity was measured by a clonogenic (HCT116) or MTT assay (T47D). Dimethyl fumarate and sulforaphane treatment increased NQO1 activity by 1.4- to 2.8-fold and resulted in a significant enhancement of the antitumor activity of mitomycin C, but not of RH1. This appeared to be due to the presence of a sufficient constitutive level of NQO1 activity in the tumor cells to fully activate the RH1. Mice were implanted with HL60 human promyelocytic leukemia cells, which have low levels of NQO1 activity. The mice were fed control or dimethyl fumarate-containing diet and were treated with RH1. NQO1 activity in the tumors increased but RH1 produced no antitumor activity in mice fed control or dimethyl fumarate diet. This is consistent with a narrow window of NQO1 activity between no RH1 activation and maximum RH1 activation. This study suggests that selective induction of NQO1 in tumor cells is not likely to be an effective strategy for enhancing the antitumor activity of RH1. In addition, we found that RH1 treatment produced significant leukopenia in mice that may be of concern in the clinic. These results suggest that the ease of reduction of RH1 by NQO1 makes it a poor candidate for an enzyme-directed approach to cancer therapy.

The bioreductive antitumour agent, mitomycin C (MMC), requires activation by reductive enzymes like NAD(P)H:quinone oxidoreductase 1 (NQO1). We used a novel approach to increase MMC efficacy by selectively inducing NQO1 in tumour cells in vivo. CD-1 nude mice were implanted with HCT116 cells, and fed control diet or diet containing 0.3% of the NQO1 inducer, dimethyl fumarate (DMF). The mice were then treated with saline, 2.0, 3.5 or 2.0 mg kg(-1) MMC and dicoumarol, an NQO1 inhibitor. The DMF diet increased NQO1 activity by 2.5-fold in the tumours, but had no effect in marrow cells. Mice given control diet/2.0 mg kg(-1) MMC had tumours with the same volume as control mice; however, mice given DMF diet/2.0 mg kg(-1) MMC had significantly smaller tumours. Tumour volumes in mice given DMF/2.0 mg kg(-1) MMC were similar to those in mice given control diet/3.5 mg kg(-1) MMC. Tumour inhibition was partially reversed in mice given DMF/2.0 mg kg(-1) MMC and dicoumarol. DMF diet/2.0 mg kg(-1) MMC treatment did not increase myelosuppression and did not produce any organ toxicity. These results provide strong evidence that dietary inducers of NQO1 can increase the antitumour activity of bioreductive agents like MMC without increasing toxicity.

Beech (Fagus sylvatica L.) seedlings were grown in an ambient or elevated CO2 concentration ([CO2]) either in small stands in microcosms for three to four seasons or individually in pots fertilized at different nutrient supply rates. Leaves at different stages of development, as well as stems and roots at the end of the growing season, were used for analysis of structural biomass and lignin. In elevated [CO2], lignification of leaves was slightly retarded compared with structural biomass production and showed a strong correlation with the activities of ionically, cell-wall-bound peroxidases but not with total soluble peroxidases or covalently wall-bound peroxidases. The effect of elevated [CO2] on lignin concentration of mature tissues was dependent on nutrient supply rate. In leaves and roots, elevated [CO2] increased the lignin concentration in dry mass in N-limited plants. In seedlings grown with high nutrient supply, the lignin concentration in dry mass was unaffected or diminished by elevated [CO2]. Because elevated [CO2] enhanced seedling growth in the high nutrient supply treatments, the total amount of lignin produced per seedling was higher in these treatments. We predict that long-term sequestration of carbon will increase as long as biomass production is stimulated by elevated [CO2] and that tissue quality will change depending on developmental stage and nutrient availability.

NAD(P)H:(quinone acceptor)oxidoreductase (DT-diaphorase) is a two-electron reducing enzyme that activates bioreductive antitumor agents and is induced by a wide variety of compounds including 1,2-dithiole-3-thione (D3T). We investigated factors influencing DT-diaphorase induction in fourteen human tumor cell lines. Four cell lines had basal DT-diaphorase activity that was increased by D3T treatment (group A), six cell lines had basal DT-diaphorase activity but the activity was not increased by D3T (group B), and four cell lines had low enzyme activity without, or with, D3T (group C). Two cell lines in group A and two cell lines in group B had a C to T polymorphism at base 609 in the NQO(1), DT-diaphorase gene, in one allele, while all four cell lines in group C were homozygous mutants. The base 609 mutant NQO(1) gene produces a protein with little enzyme activity. In group A, D3T increased NQO(1) mRNA and wild-type protein, and also increased mutant protein in the two heterozygous cell lines. In group B, the inducer slightly increased NQO(1) mRNA, did not increase the wild-type protein, but did increase the mutant protein in the two heterozygous cell lines. In group C, D3T increased NQO(1) mRNA as well as its mutant enzyme product. Transfection of the mutant NQO(1) gene into cells with two wild-type alleles did not alter DT-diaphorase activity. The results suggest that the lack of induction of DT-diaphorase activity is transcriptional in nature, that basal and induced expression of DT-diaphorase are regulated independently, and that mutant NQO(1) does not act as a dominant-negative to suppress DT-diaphorase activity.

DT-diaphorase is a two-electron-reducing enzyme that is an important activator of bioreductive anti-tumour agents, such as mitomycin C (MMC) and EO9, and is inducible by many compounds, including 1,2-dithiole-3-thiones (D3Ts). We showed previously that D3T selectively increased DT-diaphorase activity in mouse lymphoma cells compared with normal mouse marrow cells, and also increased MMC or EO9 cytotoxic activity in the lymphoma cells with only minor effects in the marrow cells. In this study, we found that D3T significantly increased DT-diaphorase activity in 28 of 38 human tumour cell lines representing ten tissue types with no obvious relationships between the tumour type, or the base level of DT-diaphorase activity, and the ability of D3T to increase the enzyme activity. Induction of DT-diaphorase activity in human tumour cell lines by 12 D3T analogues varied markedly with the D3T structure. D3T also increased DT-diaphorase activity in normal human bone marrow and kidney cells but the increases were small in these cells. In addition, D3T increased the level of enzyme activity in normal human lung cells. Pretreatment of human tumour cells with D3T analogues significantly increased the cytotoxic activity of MMC or EO9 in these cells, and the level of enhancement of anti-tumour activity paralleled the level of DT-diaphorase induction. In contrast, D3T did not effect the toxicity of EO9 in normal kidney cells. These results demonstrate that D3T analogues can increase DT-diaphorase activity in a wide variety of human tumour cells and that this effect can enhance the anti-tumour activity of the bioreductive agents MMC and EO9.

Mitomycin C (MMC) is a bioreductive antitumor agent that is activated by NADPH:cytochrome P450 reductase (EC 1.6.2.4) and NAD(P)H:(quinone acceptor) oxidoreductase (EC 1.6.99.2) (DT-diaphorase). DT-diaphorase is a two-electron reducing enzyme that is induced by a variety of chemicals, including quinones. Doxorubicin (DOX) is an anthraquinone antitumor agent that has been used clinically with MMC for combination chemotherapy in breast cancer. In this study, we investigated whether DOX could selectively induce DT-diaphorase in tumor cells and whether combining this agent with MMC in an appropriate schedule could produce synergistic antitumor activity. Treatment of EMT6 murine mammary tumor cells with DOX resulted in a 40% increase in DT-diaphorase activity in these cells, but had no effect on this enzyme in murine bone marrow cells. Combination therapy with DOX and MMC produced a 1.4-fold level of synergistic cell kill in the tumor cells, but a similar level of synergy was also observed in normal bone marrow cells. Thus, DOX can selectively induce elevated levels of DT-diaphorase in tumor cells; however, the synergy observed by combining this agent with MMC appears to be unrelated to the induction of DT-diaphorase.

NQO1 (NAD(P)H:quinoneoxidoreductase 1) is a reductive enzyme that is an important activator of bioreductive antitumor agents. NQO1 activity varies in individual tumors but is generally higher in tumor cells than in normal cells. NQO1 has been used as a target for tumor specific drug development. We investigated a series of bioreductive benzoquinone mustard analogs as a model for NQO1 targeted individualized cancer chemotherapy. We compared the tumor cell growth inhibitory activity of benzoquinone mustard analogs with sterically bulky groups of different size and placed at different positions on the benzoquinone ring, using tumor cell lines with different levels of NQO1. We demonstrated that functional groups of different steric size could be used to produce a series of bioreductive antitumor agents that were activated by different levels of NQO1 in tumor cells. This series of drugs could then be used to target cells with specific levels of NQO1 for growth inhibition and to avoid damage to normal cells, like bone marrow cells, that have low levels of NQO1. This approach could be used to develop new bioreductive antitumor agents for NQO1 targeted individualized cancer chemotherapy.

s S387 Material and Methods: Formalin-fixed, paraffin-embedded tissue sections from 186 primary colorectal carcinomas and four normal colorectal tissues were immunostained using specific monoclonal antibodies against Tn and sialyl-Tn antigens. Baseline clinicopathological characteristics and overall 5-year survival were correlated with antigen expression. Results: Of the 186 colorectal carcinomas, Tn antigen is expressed in 70 (37.6%) and sialyl-Tn antigen is expressed in 141 (75.8%). There is no staining for these antigens in normal colorectal tissues. Immunostaining measurements for Tn antigen were significantly associated with the differentiation degree (p = 0.017) of the tumors, but independent of age, gender, tumor location, depth of penetration, status of lymph nodes, lymphovascular invasion, perineural invasion and TNM stage. The expression results of sialyl-Tn antigen revealed more significant associations with the degree of differentiation (p = 0.006) and perineural invasion (p = 0.041). The poor overall survival rate of patients was significantly associated with the positive expression of sialyl-Tn (p = 0.013) but not with the expression of Tn (p = 0.650). Survival at 5 years for patients with sialyl-Tn-negative versus sialyl-Tn-positive tumors was 72.1% versus 49.2%. Cox regression multivariate analysis confirmed that TNM stage (p = 0.001) and sialyl-Tn expression (p = 0.038) were the two most important variables of for predicting overall survival. Conclusions: These results indicate that Tn and sialyl-Tn antigens appear to be useful biomarkers of poorly differentiated adenocarcinomas and mucinous carcinomas. Moreover, the positive expression of sialyl-Tn antigen is an independent predictor of poor prognosis in human colorectal carcinoma. No conflict of interest.

NAD(P)H:(quinone acceptor)oxidoreductase (DT-diaphorase) is a two-electron reducing enzyme that activates bioreductive antitumor agents and is induced by a wide variety of compounds including 1,2-dithiole-3-thione (D3T). We investigated factors influencing DT-diaphorase induction in fourteen human tumor cell lines. Four cell lines had basal DT-diaphorase activity that was increased by D3T treatment (group A), six cell lines had basal DT-diaphorase activity but the activity was not increased by D3T (group B), and four cell lines had low enzyme activity without, or with, D3T (group C). Two cell lines in group A and two cell lines in group B had a C to T polymorphism at base 609 in the NQO(1), DT-diaphorase gene, in one allele, while all four cell lines in group C were homozygous mutants. The base 609 mutant NQO(1) gene produces a protein with little enzyme activity. In group A, D3T increased NQO(1) mRNA and wild-type protein, and also increased mutant protein in the two heterozygous cell lines. In group B, the inducer slightly increased NQO(1) mRNA, did not increase the wild-type protein, but did increase the mutant protein in the two heterozygous cell lines. In group C, D3T increased NQO(1) mRNA as well as its mutant enzyme product. Transfection of the mutant NQO(1) gene into cells with two wild-type alleles did not alter DT-diaphorase activity. The results suggest that the lack of induction of DT-diaphorase activity is transcriptional in nature, that basal and induced expression of DT-diaphorase are regulated independently, and that mutant NQO(1) does not act as a dominant-negative to suppress DT-diaphorase activity.

DT-diaphorase is a two-electron reducing enzyme that activates the bioreductive anti-tumour agent, mitomycin C (MMC). Cell lines having elevated levels of DT-diaphorase are generally more sensitive to MMC. We have shown that DT-diaphorase can be induced in human tumour cells by a number of compounds, including 1,2-dithiole-3-thione. In this study, we investigated whether induction of DT-diaphorase could enhance the cytotoxic activity of MMC in six human tumour cell lines representing four tumour types. DT-diaphorase was induced by many dietary inducers, including propyl gallate, dimethyl maleate, dimethyl fumarate and sulforaphane. The cytotoxicity of MMC was significantly increased in four tumour lines with the increase ranging from 1.4- to threefold. In contrast, MMC activity was not increased in SK-MEL-28 human melanoma cells and AGS human gastric cancer cells, cell lines that have high base levels of DT-diaphorase activity. Toxicity to normal human marrow cells was increased by 50% when MMC was combined with 1,2-dithiole-3-thione, but this increase was small in comparison with the threefold increase in cytotoxicity to tumour cells. This study demonstrates that induction of DT-diaphorase can increase the cytotoxic activity of MMC in human tumour cell lines, and suggests that it may be possible to use non-toxic inducers of DT-diaphorase to enhance the efficacy of bioreductive anti-tumour agents. © 1999 Cancer Research Campaign

DT-diaphorase (EC 1.6.99.2) is a flavoprotein that catalyses two-electron reduction of quinones, quinone imines, and nitrogen oxides. It is a Phase II detoxifying enzyme that can detoxify chemically reactive metabolites, and may be important in an early cellular defense against tumorigenesis. DT-diaphorase is also an activating enzyme for bioreductive antitumor agents like mitomycin C (MMC) and EO9. DT-diaphorase is induced in many tissues by a wide variety of compounds including dithiolethiones and isothiocyanates. Dithiolethiones are chemoprotective agents against a variety of chemical carcinogens in animal models, and the dithiolethione analogue, oltipraz, is currently in Phase I and Phase II clinical chemoprevention trials. Similarly, the isothiocyanate derivative, sulforaphane, blocks the formation of carcinogen-induced mammary tumors in rats. The low toxicity of these inducers of DT-diaphorase makes them suitable for use as chemopreventive agents in high-risk individuals. Cells with elevated DT-diaphorase levels are generally more sensitive to bioreductive antitumor agents. Thus, we suggested that the antitumor efficacy of bioreductive agents can be enhanced by selective induction of DT-diaphorase in tumor cells compared with normal cells. We showed that 1,2-dithiole-3-thione (D3T) can increase the level of DT-diaphorase activity and the cytotoxic activity of bioreductive agents in mouse lymphoma cells without increasing these activities in normal mouse marrow cells. D3T also increased DT-diaphorase activity in 24 of 33 human tumor cell lines representing nine tissue types with no obvious relationships between the tumor type, or the base level of DT-diaphorase activity, and the ability to increase enzyme activity. A series of dithiolethione analogues and dietary components were also shown to be good inducers of DT-diaphorase in human tumor cells. D3T increased DT-diaphorase activity in normal human bone marrow and kidney cells but the increases were small in these cells. Combination treatment with D3T and EO9 increased cell kill in HL-60 human leukemia cells compared with EO9 alone, but had no effect on EO9 toxicity in normal human kidney cells. Similarly, D3T increased tumor cell kill by EO9 in H661 human lung cancer cells and by MMC in T47D human breast cancer cells. Thus, inducers of DT-diaphorase may play an important role in cancer chemoprevention programs and may also be useful in enhancing the antitumor efficacy of bioreductive agents.

Bioreductive antitumour agents are an important new class of anticancer drugs that require activation by reduction. The two-electron reducing enzyme, DT-diaphorase, has been shown to be an important activating enzyme for the bioreductive agents, mitomycin C (MMC) and EO9. Incubation of L5178Y murine lymphoma cells in vitro with 1,2-dithiole-3-thione (D3T) increased the level of DT-diaphorase activity in these cells 22-fold. In contrast, D3T had no effect on the DT-diaphorase level in normal mouse bone marrow cells. Combination therapy with D3T and MMC or EO9, produced a 2- or 7-fold enhancement, respectively, of the cytotoxic activity of these antitumour agents in L5178Y cells. By comparison, D3T did not enhance the activity of MMC in marrow cells and produced only a small increase in EO9 cytotoxicity in these cells. The DT-diaphorase inhibitor, dicoumarol, inhibited the effect of D3T on the antitumour activity of the bioreductive agents, supporting the proposal that the enhanced anticancer activity was due to the elevated enzyme level. These findings suggest that D3T, or other inducers of DT-diaphorase, could be used to enhance the antitumour efficacy of bioreductive antitumour agents.

An L5178Y murine lymphoblast cell line resistant to 3'-(3-cyano-4-morpholinyl)-3'-deaminoadriamycin (MRA-CN), L5178Y/MRA-CN, was isolated and characterized. L5178Y/MRA-CN cells were 9.6-fold resistant to MRA-CN compared with parental cells. The resistant cell line also displayed 2-fold resistance to 3'-(4-morpholinyl)-3'-deaminoadriamycin but was not cross-resistant to Adriamycin or chlorambucil. Uptake of MRA-CN was slightly reduced in the resistant cells compared to sensitive cells, but the distribution of the drug within the cells was unchanged. DNA interstrand cross-linking by MRA-CN was not significantly different in the sensitive and resistant cell lines, but MRA-CN was slightly less effective in inhibiting both DNA and RNA synthesis in L5178Y/MRA-CN cells compared with parental cells. NADPH cytochrome P-450 reductase activity was increased in L5178Y/MRA-CN cells compared to parental cells, while the activity of DT-diaphorase was decreased in the resistant cells. The levels of glutathione and glutathione S-transferase activity were increased in the resistant cells compared to sensitive cells; however, pretreatment of L5178Y/MRA-CN cells with buthionine sulfoximine to reduce the glutathione level did not reverse the resistance of these cells to MRA-CN. MRA-CN induced DNA fragmentation that was characteristic of apoptosis in both L5178Y and L5178Y/MRA-CN cells at equitoxic drug concentrations. However, apoptosis occurred more rapidly in L5178Y/MRA-CN cells compared with parental cells. Thus, MRA-CN induces apoptosis in L5178Y cells, and this effect may be important for the anti-tumor activity of this agent. In contrast, DNA interstrand cross-linking does not appear to be the primary mechanism responsible for the cytotoxicity of MRA-CN in these cells.

The quinone antitumor agent mitomycin C is preferentially toxic to some cells under hypoxic and acidic conditions. The two-electron reducing enzyme DT-diaphorase may be a major contributor to mitomycin C activation under aerobic conditions, but its role in drug activation under hypoxic and acidic conditions is unclear. In this study, we observed that mitomycin C produced increased DNA cross-linking and cytotoxicity in Chinese hamster ovary cells at pH 6.6, compared with pH 7.2, under aerobic conditions, but drug activity was similar at these pH values under hypoxic conditions. The DT-diaphorase inhibitor dicoumarol completely inhibited the enhanced activity of mitomycin C at acidic pH under aerobic conditions but had no effect on DNA cross-linking or cytotoxicity under hypoxic conditions. These finding suggest that the enhanced activity of mitomycin C at acidic pH, in air, is due to increased drug activation by DT-diaphorase. However, the role of DT-diaphorase in activating mitomycin C under hypoxic conditions appears to be limited, even at acidic pH.

The role of the two-electron reducing enzyme DT-diaphorase in the activation of mitomycin C under hypoxic conditions was investigated. Mitomycin C activity was compared in L5178Y murine lymphoblasts, which have low levels of DT-diaphorase activity, and L5178Y/HBM10 cells, which have elevated levels of enzyme activity. The cytotoxic and DNA cross-linking activities of mitomycin C were greater in L5178Y/HBM10 cells than in L5178Y cells. In L5178Y/HBM10 cells, dicoumarol, an inhibitor of DT-diaphorase, decreased cell kill and DNA cross-linking by mitomycin C in air but had no significant effect on these activities under hypoxia. By comparison, in L5178Y cells, dicoumarol had no effect on drug activity under either aerobic or hypoxic conditions. A model for the activation of mitomycin C by both one-electron and two-electron reduction is proposed. Our findings suggest that two-electron reduction by DT-diaphorase has only a limited role in the activation of mitomycin C under hypoxic conditions, although this enzyme appears to be an important contributor to drug activation under aerobic conditions.

Previous studies have demonstrated that the quinone group may play an important role in modulating the alkylating activity of quinone alkylating agents. Introduction of a quinone moiety markedly increased the alkylating activity and cytotoxic activity of the model quinone alkylating agents benzoquinone mustard and benzoquinone dimustard. However, the cytotoxic and DNA-damaging activity of benzoquinone mustard was considerably greater than that of benzoquinone dimustard. In this study, we have investigated the role of the quinone group as a modulator of alkylating activity in these antitumor agents, using extracellular assays to eliminate differences due to cellular drug uptake and metabolism. Evidence was obtained that the alkylating activities of both benzoquinone mustard and benzoquinone dimustard were enhanced by reduction of the quinone group. In addition, when these agents were reduced, they displayed equal alkylating activity. This finding suggests that the difference in the activity of these agents in cells is not due to intrinsic differences in alkylating activities of the activated forms of these agents. Electrochemical studies revealed that benzoquinone dimustard has a lower redox potential than benzoquinone mustard and, thus, is less easily reduced. Inactivation and spectroscopic studies suggested that a major reason for the differences in activity between benzoquinone mustard and benzoquinone dimustard may be the rapid inactivation of the dimustard before its reduction. This effect may be enhanced by the lower redox potential of benzoquinone dimustard, compared with benzoquinone mustard. These findings support the hypothesis that the quinone group can modulate the alkylating activity of quinone alkylating agents; however, the mechanisms by which this modulation occurs may vary for different antitumor agents.

The role of the quinone group in the antitumor activity of quinone alkylating agents, such as mitomycin C and 2,5-diaziridinyl-3,5-bis(carboethoxyamino)-1,4-benzoquinone, is still uncertain. The quinone group may contribute to antitumor activity by inducing DNA strand breaks through the formation of free radicals and/or by influencing the alkylating activity of the quinone alkylators. The cytotoxic activity and DNA damage produced by the model quinone alkylating agents, benzoquinone mustard and benzoquinone dimustard, were compared in L5178Y murine lymphoblasts sensitive and resistant to the model quinone antitumor agent, hydrolyzed benzoquinone mustard. The resistant cell lines, L5178Y/HBM2 and L5178Y/HBM10, have increased concentrations of glutathione and elevated catalase, superoxide dismutase, glutathione S-transferase, and DT-diaphorase activity. L5178Y/HBM2 and L5178Y/HBM10 cells were 7.4- and 8.5-fold less sensitive to benzoquinone mustard and 1.7- and 4.3-fold less sensitive to benzoquinone dimustard, respectively, compared with sensitive cells, but showed no resistance to the non-quinone alkylating agent, aniline mustard. The formation of DNA double strand breaks by benzoquinone mustard was reduced by 2- and 8-fold in L5178Y/HBM2 and L5178Y/HBM10 cells, respectively, while double strand break formation by benzoquinone dimustard was reduced only in the L5178Y/HBM10 cells. The number of DNA-DNA cross-links produced by benzoquinone mustard was 3- and 6-fold lower, and the number produced by benzoquinone dimustard was 35% and 2-fold lower in L5178Y/HBM2 and L5178Y/HBM10 cells, respectively, compared with L5178Y parental cells. In contrast, cross-linking by aniline mustard was unchanged in sensitive and resistant cells. Dicoumarol, an inhibitor of DT-diaphorase, increased the cytotoxic activity of both benzoquinone mustard and benzoquinone dimustard in L5178Y/HBM10 cells. This study provides evidence that elevated DT-diaphorase activity in the resistant cells contributes to resistance to benzoquinone mustard and benzoquinone dimustard, possibly by decreasing the formation of the semiquinone intermediates of these agents. The altered reduction of the quinone groups in the resistant cells may be responsible for the decreased DNA-DNA cross-linking and lowered induction of DNA strand breaks by the quinone alkylating agents. These findings demonstrate that the quinone group can modulate the activity of quinone alkylating agents. The study also suggests that the semiquinone intermediates of benzoquinone mustard and benzoquinone dimustard may be the active alkylating species of these two agents.

Objectif: Etudier l'effet du cisplatin (CDDP) sur les cellules de carcinome epidermoide humain FADU et de determiner si le thiosulphate de sodium (TSS) un agent protecteur contre l'ototoxicite du cisplatin, affecte son activite tumoricidale. Methode: Nous avons cultive les cellules tumorales FADU. Elles ont ensuite ete exposees a des concentrations variables de CDDP avec et sans ajout de STS. Nous avons ensuite determine l'effet du traitement sur les cellules FADU a l'aide d'un assay au 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT). Resultats: Nous avons genere des courbes dose-reponse pour les cellules FADU exposees au cisplatin et au STS. L'exposition simultanee au STS a inhibe l'activite tumoridicale du CDDP in vitro. Conclusion: L'administration simultanee de STS a une culture in vitro de cellules FADU a mene a l'inhibition de l'activite tumoricidale de CDDP.

Sommaire Objectif: Etudier l'effet du cis-diamminedichloroplatinum (CDDP) sur les cellules de carcinome epidermoide FADU dans un modele de souris nues et de determiner l'effet du thiosuophate de sodium (TSS) sur l'activite du CDDP. Methode: Nous avons inocule les cellules tumorales FADU dans les deux flancs de souris nues CD1. Elles ont ensuite ete randomisees en 4 groupes ; controle, CDDP seul, TSS seul et CDDP et TSS ensemble. Nous avons utilise des compas gradues pour mesurer la tumeur aux trois jours. Resultats: Les volumes tumoraux ont ete calcules comme une ellipsoide et traces en relation avec le temps. Conclusion: Le CDDP a inhibe la croissance des cellules FADU par rapport au controle (p

The immune response of experimentally infected hamsters and human patients to Mycoplasma pneumoniae was examined by radioimmunoprecipation in conjunction with gel electrophoresis and fluorography. Both intrinsically and extrinsically labeled mycoplasma proteins were coincubated with acute and convalescent sera in a radioimmunoprecipitation assay. Two M. pneumoniae proteins were selectively precipitated by convalescent sera. These predominant immunogens were trypsin-sensitive, antibody-accessible surface proteins that co-migrate on polyacrylamide gels with proteins P1 and P2, which were previously implicated by us as mediators of cytadsorption. Anti-M. pneumoniae antiserum did not precipitate radiolabeled antigens derived from Mycoplasma orale or Mycoplasma salivarium. These data indicate that M. pneumoniae infection stimulates a specific and highly targeted host antibody response to key proteinaceous immunogens.

Hemadsorbing revertants were isolated from spontaneous hemadsorption-negative, avirulent mutants of Mycoplasma pneumoniae. The revertants simultaneously reacquired specific proteins absent in their homologous mutants, along with neuraminidase-sensitive adherence to the respiratory epithelium and virulence. Peptide mapping and immunological analysis indicated no precursor-product relationships among certain of these proteins.

Rabbit aorta predominantly synthesizes prostacyclin (PGI2). a potent inhibitor of platelet aggregation and a strong vasodilator. We report here the effect of vitamin E depletion and repletion on endogenous release of PG Iby rabbit aorta. Serum pyruvate kinase was monitored for myopathy. The endogenous release of PG 12 by the aorta, detected as its stable metabolite 6- keto-PGF1a, was inhibited by indomethacin and was inversely related to the size of aorta sections, Deficient aorta synthesized significantly less PGI2 than those from control animals. Repletion of deficient animals for 48 h completely restored the PGI2 release to a level comparable to the control values. The data showed that PGI2 synthesis by aorta can be influenced by dietary vitamin E. Am. J. Clin. Nutr. 34: 2341-2347, 1981.

Twenty-two mutants of Mycoplasma pneumoniae spontaneously deficient in hemadsorption were isolated. Examination of mutant protein profiles by one- and two-dimensional polyacrylamide gel electrophoresis permitted the grouping of these mutants into four classes. The largest class of mutants was deficient in four high-molecular-weight proteins (215,000, 210,000, 190,000, and 140,000). A second class of mutants lacked three proteins previously designated A, B, and C (72,000, 85,000, and 37,000, respectively). A single mutant, in addition to lacking proteins A, B, and C, was missing a fourth protein of 165,000 molecular weight. The remaining mutants exhibited protein profiles apparently identical to that of the wild-type strain. All mutant strains attached to the respiratory epithelium of hamster tracheal rings in vitro at reduced levels; however, mutants lacking proteins A, B, and C recognized only neuraminidase-insensitive receptors. None of the mutants tested produced detectable pneumonia in intranasally inoculated hamsters, although one mutant class demonstrated low-level survival in vivo.

Origin of Iron Ores Recent studies of the origin of the iron formations of the Lake Superior region, including those of Collins, Gruner, Hawley, and others yet unpublished, tend, on the whole, to show that the iron formations are inorganic chemical precipitates, that organic agencies have played a relatively small part, that volcanic sources have made notable contributions, and that normal processes of weathering have likewise been effective. All of these factors have been previously recognized, but now they can be more specifically identified. The studies of secondary concentration of the iron ores themselves have not changed earlier concepts of the processes. Correlations It has long been agreed that the Animikie of the north shore and the Gogebic iron-bearing series (“Upper Huronian”) are the same. In the past this has been correlated with the uppermost of the Huronian series in the remaining districts of the south shore, but it now . . .

THE PROBLEM From the beginning of history, nations have differed in their physical environments and therefore in their economic opportunities. Their activities have been influenced and limited by climate, soil, topography, and accessibility. Only in the last century have mineral resources loomed as an important element in man’s environment because they were not used on a large scale until the Industrial Revolution. The world’s mineral supplies are large enough for all if they were equally distributed among the nations, but unfortunately they are not. Nations favored by their possession of mineral supplies necessary for industrialization are the ones which in modern times have taken a commanding position in world affairs. Military power is coming more and more to be measured in terms of guns, ships, automobiles, and airplanes, rather than by man power alone, and these implements are in turn limited by the capacity of the industrial plants and the . . .