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141.
142.
We reported previously that p.o. administered 5-iodo-2-pyrimidinone-2'-deoxyribose (IPdR) was efficiently converted to 5-iodo-2'-deoxyuridine (IUdR) in athymic mice (T. J. Kinsella et al., Cancer Res., 54: 2695-2700, 1994). Here, we further evaluate IPdR metabolism, systemic toxicity, and percentage DNA incorporation in athymic mouse normal tissues and a human colon cancer xenograft (HT29) using higher p.o. doses of IPdR. These data are compared to results using a continuous infusion of IUdR at the maximum tolerable dose. We also evaluate IPdR metabolism in cytosolic extracts from normal human liver, normal human intestine, and human colorectal cancer specimens. Athymic mice tolerated a daily p.o. bolus of up to 2 g/kg IPdR for 6 days with minimal host toxicity (< or = 10% body weight loss). There was rapid conversion of IPdR to IUdR, with peak plasma levels of IUdR of 40-75 microM at 10 min following a p.o. IPdR bolus of 250-1500 mg/kg. The percentage IUdR-DNA in the HT29 s.c. human tumor xenografts increased 1.5 times (2.3-3.6%) with IPdR doses above 1 g/kg/day for 6 days, whereas the percentage IUdR-DNA incorporation in two proliferating normal tissues (4-4.5% in intestine; 1.6-2.2% in bone marrow) and a quiescent normal tissue (< or = 1% in liver) showed < 1.5-fold increases with the IPdR dose escalation between 1-2 g/kg/day for 6 days. In contrast, using a continuous infusion of IUdR at 100 mg/kg/day, significant systemic toxicity (> 20% body weight loss) was found by day 6 of the infusion. Steady-state plasma IUdR levels were 1.0-1.2 microM during the 6-day infusion, and percentage IUdR-DNA incorporations of 2.3, 8, 6, and 1% were measured in s.c. tumors, normal intestine, normal bone marrow, and normal liver, respectively, following the 6-day infusion. Thus, the p.o. IPdR schedule has an improved therapeutic index, based on percentage IUdR-DNA incorporation in normal and tumor tissues, compared to continuous infusion IUdR at the maximum tolerable dose in athymic mice with this human tumor xenograft. Additionally, a tumor regrowth assay to assess the radiation response of HT29 s.c. xenografts showed a 1.5-fold enhancement (time to regrow to 300% initial tumor volume) with IPdR (1000 mg/kg/day for 6 days) plus fractionated irradiation (XRT; 2 Gy/day for 4 days), compared to XRT (2 Gy/day for 4 days) alone. No enhancement in the radiation response of HT29 s.c. xenografts was found with continuous infusion IUdR (100 mg/kg/day for 6 days) plus XRT (2 Gy/day for 4 days), compared to XRT alone. Using cytosolic extracts from normal human liver specimens, we found a rapid (15-min) conversion of IPdR to IUdR. Coincubation of liver cytosol with IPdR and allopurinol, an inhibitor of xanthine oxidase, had no inhibitory effect on IPdR metabolism, whereas coincubation with IPdR and isovanillin or menadione, analogue substrates for aldehyde oxidase, effectively reduced the amount of IPdR oxidized to IUdR. Significantly less metabolism of IPdR to IUdR was seen in cytosolic extracts from normal human intestine specimens, and no metabolism of IPdR was found in cytosolic extracts from colorectal liver metastases in two patients and from the HT29 human colon cancer xenografts in athymic mice. These additional data indicate that IPdR has the potential for clinical use as a p.o. prodrug for IUdR-mediated radiosensitization of resistant human cancers. 相似文献
143.
I Mahmood 《Canadian Metallurgical Quarterly》1998,63(26):2365-2371
The objective of this study is to predict pharmacokinetic parameters (clearance, volume of distribution at steady state, and elimination half-life) in humans from animal data for drugs which are renally secreted in humans. Pharmacokinetic parameters of ten drugs were scaled-up from animal data obtained from the literature. Using simple allometry (pharmacokinetic parameter of interest vs body weight), total, renal and nonrenal clearances, volume of distribution and half-life were predicted in humans. The predicted parameters were compared with the observed parameters. The results of the study indicated that it is likely that the predicted total and renal clearances from animal data will be underestimated in humans for renally secreted drugs. The prediction of renal clearance was improved by normalizing the renal clearance by a 'correction factor' for animals who exhibited renal secretion. The predicted volume and half-life were comparable with the observed values in man. Overall, the results of this study indicate that caution should be employed in interpreting the total and renal clearance of renally secreted drugs predicted by the allometric approach. 相似文献
144.
Mahmood Thobani Levente L. Diosady 《Journal of the American Oil Chemists' Society》1997,74(3):207-214
The equilibrium relationships in the extraction process that was developed in our research laboratory for the treatment of
canola were studied. In the process, hexane is used as well as CH3OH that contains 5% (vol/vol) H2O and 0.08% (w/w) NaOH to simultaneously produce improved meal and high-quality oil. Equilibrium data for canola oil in the
hexane-CH3OH/H2o/NaOH, meal-hexane, and meal-CH3OH/H2O/NaOH-hexane systems are reported. A high partition coefficient for oil between hexane and the polar phase provided a large
driving force for mass transfer. The presence of the CH3OH phase improved oil extraction, probably by rupturing the cell structure. The process proved to be a somewhat less desirable
replacement for CH3OH/H2O/NH3 extraction and recovered 93.5% of the oil and 91.8% of the protein in the seed, while with CH3OH/H2O/NH3, the oil and protein recoveries were 96.8 and 94.0%, respectively. The NaOH treatment removed only 50.2% of the glucosinolates,
and some of the oil was hydrolyzed by the NaOH, making the process less effective, despite its simplicity. 相似文献
145.
Zhongrui Li Enkeleda Dervishi Yang Xu Viney Saini Meena Mahmood Olumide Dereck Oshin Alexandru R. Biris Alexandru S. Biris 《Catalysis Letters》2009,131(3-4):356-363
A comparison of different catalyst systems (Fe–Mo, Co–Mo or Ni–Mo nanoparticles supported on calcium carbonate) has been performed in order to optimize the carbon nanotube (CNT) growth. The influences of the reaction temperature, metal loading and carbon source on the synthesis of CNTs were investigated. Dense CNT networks have been synthesized by thermal chemical vapor deposition (CVD) of acetylene at 720 °C using the Co–Mo/CaCO3 catalyst. The dependence of the CNT growth on the most important parameters was discussed exemplarily on the Co catalyst system. Based on the experimental observations, a phenomenological growth model for CVD synthesis of CNTs was proposed. The synergy effect of Mo and active metals was also discussed. 相似文献
146.
147.
Simultaneous measurements of thermal conductivity and thermal diffusivity of composite red-sand bricks, glycerine and mercury have been made at room temperature by the recently developed transient plane source (TPS) technique. This paper describes, in brief, the theory and the experimental conditions for the simultaneous measurements of thermal conductivity and thermal diffusivity of insulators, fluids and metals. The source of heat is a hot disc made out of bifilar spirals. The disc also serves as a sensor of temperature increase in the sample. The measured values of the thermal conductivity and thermal diffusivity of these samples are in agreement with the values reported earlier using other methods. The advantage of the TPS technique is the simplicity of the equipment, simultaneous information on thermal conductivity and thermal diffusivity, and also the applicability of the technique to insulators, fluids and metals. 相似文献
148.
Theoretically the computer can offer the architect significant help during the preliminary design stages. To take full benefit of its capabilities it is necessary to use the computer for the design process itself. To this end, a program has been written that concentrates on ease of use so that the machine does not impede the creative process. The program works through the manipulation of design elements such as spaces and windows, not graphical ones. The result is a tool which offers improved efficiency, but is very different from current methods that use paper in preliminary design. 相似文献
149.
D.E. Brown M.N. Mahmood A.K. Turner S.M. Hall P.O. Fogarty 《International Journal of Hydrogen Energy》1982,7(5):405-410
An electrocatalyst for hydrogen evolving cathodes has been developed for use in alkaline media. The materials employed in manufacturing the coating are relatively cheap transition metals. The results of a variety of performance tests are reported. The electrodes exhibit a low overvoltage for hydrogen evolution (70–90 mV at 70°C and 1A cm?2 in 5 N KOH), stability to abuse (e.g. current interruption or reversal) and a long cathode life under operating conditions. 相似文献
150.
Stanton de Riel Imrana Mahmood Francisco Alvarez Shashank Mahashabde Sharad Govil 《Drug development and industrial pharmacy》1993,19(6):643-652
An assay of water in adhesive monolithic transdermal drug dosage forms ('patches'), using lamination to Tyvek, and gaseous extraction in an evaporator oven into a Karl Fischer titrator, is described. The method is simple, linear, accurate, specific and more sensitive than alternatives. 相似文献