5-[125I]iodo-2'-deoxyuridine in the radiotherapy of brain tumors in rats.

UNLABELLED: Glial neoplasms of the human central nervous system have defied treatment, in part because of the limited selectivity of available cytotoxic agents. The thymidine analog 5-iodo-2'-deoxyuridine radiolabeled with the Auger electron emitter 125I (125IUdR) is highly toxic to dividing cells when it is deoxyribonucleic acid incorporated, but it is relatively innocuous when located outside the nucleus. Previous studies have shown that 125IUdR has significant antineoplastic potential against mammalian cells in vitro and direct administration of 125IUdR is effective therapy for ovarian ascites tumors in mice and neoplastic meningitis in rats. Studies using external gamma imaging and autoradiography have also shown that direct intratumoral administration of 123IUdR/125IUdR into intracerebral 9L gliosarcomas in rats results in selective uptake of the radionuclide into tumor cells. Based on these encouraging results, we have evaluated the therapeutic potential of 125IUdR in rats bearing intracerebral 9L gliosarcomas. METHODS: Iodine-125-IUdR was infused intracerebrally over a 2-day period into rats bearing 1-day-old 9L tumors and over a 6-day period into animals with 9-day-old 9L tumors; equimolar concentrations of 127IUdR were infused into control animals. Tumor growth was monitored by contrast-enhanced 1H MRI and animal survival was followed over time. RESULTS: Intracerebral tumors (3-7 mm) were readily detected by MRI. Tumor-bearing rats treated with 127IUdR succumbed within 17-24 days, whereas tumor-bearing animals treated with 125IUdR survived significantly longer, and 10%-20% of the animals were cured of tumors. CONCLUSION: These data substantiate the antineoplastic potential of 5-[125I]iodo-2'-deoxyuridine and indicate that it may be a useful agent for the therapy of solid tumors that are accessible to direct radiopharmaceutical administration.

Amelioration of ischemic calcium overload correlates with high-energy phosphates in senescent myocardium.

Previously, we have shown that potassium and magnesium (K-Mg, 20 mM each) cardioplegia ameliorated cytosolic calcium ([Ca2+]i) accumulation and was associated with enhanced functional recovery after surgically induced global ischemia in the aged heart. K-Mg cardioplegia was also shown to enhance cytosolic cytochrome oxidase I activity and mRNA levels, suggesting that enhanced functional recovery may involve the preservation of high-energy phosphates. To investigate this hypothesis, 31P nuclear magnetic resonance was used to measure serial alterations in phosphocreatine (PCr), inorganic phosphate, nucleoside triphosphate (NTP), intracellular free magnesium (Mgf), and intracellular pH (pHi) in Langendorff-perfused, aged (135 wk) rabbit hearts during preischemia, global ischemia (30 min), and reperfusion (30 min). K-Mg cardioplegia retarded PCr depletion (P < 0.05) and significantly enhanced NTP preservation (P < 0.05) during ischemia and reperfusion. K-Mg cardioplegia also attenuated the increase in Mgf during ischemia (P < 0.05). These results were correlated with amelioration of [Ca2+]i accumulation during ischemia and preservation of left ventricular function after reperfusion and suggest that optimal functional recovery from surgically induced ischemia is provided by K-Mg cardioplegia in the aged myocardium.

Relative phosphocreatine and nucleoside triphosphate concentrations in cerebral gray and white matter measured in vivo by 31P nuclear magnetic resonance.

Rates of ATP metabolism generally are higher in cerebral gray matter compared to white matter. In order to study the physiology of this regional difference in vivo, the 1-dimensional chemical shift imaging technique (1D-CSI) was used to acquire 31P nuclear magnetic resonance spectra from 2.5 mm slices of 4-week old piglet brains. Spectra from predominantly gray matter slices (estimated 76% gray matter, 7 mm below the scalp) were compared to predominantly white matter slices (56% estimated white matter, 13 mm below the scalp) as assessed by magnetic resonance images. The 1D-CSI technique introduced no systematic changes in the ratio of signals from a single chamber phantom containing a phosphocreatine (PCr) and ATP solution. Gray matter slices showed a PCr/NTP ratio of 0.93 +/- 0.11 (mean +/- S.D.) using a 2 s interpulse interval, a value very close to the ratio in surface coil localized spectra. The predominantly white matter slices showed a PCr/NTP ratio of 1.32 +/- 0.18 (P < 0.02 for gray versus white matter). Using the estimated percentages of gray and white matter in the two slices and calculated concentrations from fully relaxed spectra, the gray matter PCr/NTP ratio is approximately 0.77, while the ratio in white matter is approximately 2.18. The difference in PCr/NTP measured in vivo suggests that either the total NTP concentration is higher or the steady state PCr concentration is lower in gray matter than in white matter in the piglet brain.

31P nuclear magnetic resonance spectroscopic evaluation of liver preservation solutions.

The individual effects of verapamil and 2 antioxidants on perfused rat liver nucleoside triphosphate (NTP) recovery following cold storage in University of Wisconsin (UW) solution was assessed using 31P nuclear magnetic resonance spectroscopy. The pharmacological agents were added to UW solution and were present only during organ storage. NTP recovery was significantly higher for the 24-hr UW + 40 microM verapamil group as compared with the 24-hr UW group. None of the other pharmacological agents caused a significant increase in NTP recovery. These findings suggest that addition of verapamil to UW organ preservation solution may result in better poststorage liver function.