Noninvasive fluorescent study in situ and in real time of glucose effects on the pharmacokinetic of calcein

This study was undertaken to compare the effect of glucose injection on the pharmacokinetic behavior of a soluble dye in normal and tumoral tissues. The measurements were done using a noninvasive fluorescent spectroscopy in situ and in real time. The experiments were performed on three groups of animals with calcein as a soluble pH-insensitive fluorescent dye combined or not with glucose. Glucose solution was injected 5 or 30 min before calcein. Fluorescence emission intensity was recorded on normal and tumor tissues with an optical multichannel analyzer. Calcein concentration was also measured in blood using repetitive blood sampling. In the control group (without glucose injection), calcein is rapidly cleared from the blood, with a slow tissue clearance. Fluorescence of normal tissue was higher than fluorescence measured in tumor tissue. When glucose is injected 5 min before calcein, there was a rapid increase of tissue fluorescence followed by a plateau remaining during the whole experiment. No difference between tumor and normal tissue fluorescence intensity was observed. When glucose was injected 30 min before calcein, the plateau phase was reduced to 50 min in normal tissue. Tumor tissue fluorescence displays no distinct plateau phase. These results clearly showed the effect of glucose injection in situ and in real time, by a noninvasive method, on the pharmacokinetic of a soluble dye in a tumor tissue compared to a normal tissue. Differences between blood compartment and tissues kinetic profiles were also clearly demonstrated.

[Markers of the metabolic changes arising as a result of ionizing radiation exposure]

Time-related changes have been studied in the content of extracellular DNA, Fe(3+)-transferrin (TF), and Cu(2+)-ceruloplasmin (CP) in the blood plasma and the activity of ribonucleotide reductase (RR) in the tumor cells and spleen of mice during the development of acute lympholeukosis P-388 and after ionizing irradiation. At the initial stages of leucosis P-388, the content of extracellular DNA increases, the TF and CP pools in the blood plasma enlarge, and the RR activity in the tumor cells and spleen of tumoral mice markedly increases. A dose-dependent increase in RR activity was also recorded in the spleen of 5-day-old rats within 15-30 min after irradiation. The causes of these changes and the possibility for these indices to be used in estimating leucosis risk are discussed. Radiation-induced increases in RR activity are discussed in relation to the SOS-response to DNA damage; an increased pool of deoxyribonucleotides is necessary for repair of DNA. The mean contents of extracellular DNA, TF and CP in the blood plasma were obtained from children of different ages degrees of radioactive contamination suffering the consequences of the accident at the Chernobyl' Nuclear Power Station (n = 155). Groups of children have been isolated with increased, sharply decreased, and close to normal levels of extracellular DNA, TF, and CP. The lowered TF pool was observed in children with thyroid glands damaged by incorporated radioactive iodine with the degree of suppression determined by the dose. For most children subject to general irradiation, the TF and CP pools in the blood were higher than in the control, suggesting an adaptive response to irradiation.

Liposomal vincristine which exhibits increased drug retention and increased circulation longevity cures mice bearing P388 tumors

Prolonged exposure to vincristine correlates with improved therapeutic activity. In this work, two methods are used to increase the circulation longevity of liposomal formulations of vincristine. The first involves incorporation of the ganglioside GM1, which acts to increase the circulation longevity of liposomal carriers, while the second approach relies on a modification of the vincristine encapsulation procedure which enhances drug retention. It is shown that these approaches are synergistic and increase the circulation half-life of vincristine from approximately 1 h to greater than 12 h. This results in a dramatic improvement in the therapeutic activity of liposomal vincristine as measured using a murine P388 lymphocytic leukemia model. At doses above 2 mg/kg, the optimized liposomal vincristine formulation cures greater than 50% of mice bearing the P388 tumor, whereas free vincristine results in no cures.

[The effect of ascitic fluid globulins on the growth of leukemia P388/DOX and Ehrlich's carcinoma in mice]

The study was performed to investigate the effect of ascitic fluid globulins of tumor on tumor growth and life span of mice. The globulins are shown to shorten the life span of Ehrlich tumor mice from 86.8 to 61.8 days, to increase 3-5-fold the growth rate of Ehrlich carcinoma and P388/DOX tumor. It was found that globulins of ascitic fluids and serum globulins of tumor have equal effects of tumor growth. It is proposed to use globulins of ascitic fluid to study the globulin role in tumor growth.

Characterization of tumorous and normal tissue using a pH-sensitive fluorescence indicator (5,6-carboxyfluorescein) in vivo

The pH of the interstitial fluid of malignant tumours tends to be lower than that of normal tissue and is depressed by glucose administration. This study aimed to evaluate the effectiveness of dual-wavelength fluorometry using a pH-dependent indicator (5,6-carboxyfluorescein: 5,6-CF) for the detection of tumour areas in vivo. 5,6-CF has two main characteristics: it has two wavelengths of maximum absorbance (465 and 490 nm) and its fluorescence emission (maximum, 515 nm) increases as a function of pH in the physiological pH range of 6-7.4. The experimental study was performed on 28 CDF mice bearing lymphoid leukaemia P388 grafted subcutaneously. The tissue pH values were evaluated from the ratio of the fluorescence intensities (I490/I465) on the basis of a calibration curve linking pH measurements performed within the tissue using a microelectrode and values of the fluorescence intensity ratio. The fluorescence intensity reached its maximum value 60 min after 5,6-CF and glucose administration, followed by a plateau (90 min) when the ratios remained constant at 1.79 +/- 0.05 for normal tissue and 1.35 +/- 0.04 for tumour tissue (p less than 0.005). These results were correlated with the pH measurements in accordance with the calibration curve. This study validates the relevance of dual-wavelength fluorometry using a pH-dependent indicator to characterize in vivo normal and tumour tissues after glucose administration.

[The effect of thymalin on the count of large granular lymphocytes in the peripheral blood of mice with leukemia P388]

Effect of thymaline injections on peripheral blood natural killer cells in mice with p388 leukemia has been studied. The content of natural killers that have been identified as large granular lymphocytes decreased in blood of leukemia mice. Multiple thymaline injections (0.66 mg/kg) maintain the numbers of the lymphocytes at the level of control animals but did not increase the life span of leukemia mice.

[Studies on the possible causes of decreasing NK cell activity in tumor-bearing mice. II. Serum and peritoneal exudate from ascitic tumor-bearing mice suppress NK cell activity]

Previous studies showed that the depressed NK cell activity in tumor-bearing mice was not due to the decrease of NK cell number. The results of this report indicate that the depressed NK cell activity in tumor-bearing mice might be due to an inhibitory factor, which probably was secreted by tumor-cells. We found that sera and peritoneal exudates from S180 or P388 tumor-bearing mice were able to inhibit the normal NK cell activity. Spleen cells incubated with the peritoneal exudate for 24 hours before assay demonstrated significantly depressed NK activity. Treatment of peritoneal exudate with a large number of spleen cells did not alter the inhibitory effect of peritoneal fluid, indicating that the inhibitory factor might not be membrane antigen shedding from the tumor cells, but may be actively secreted by them.

Potentiation of the chemotherapeutic action of 5'-deoxy-5-fluorouridine in combination with guanosine and related compounds

The effect of inosine, guanosine, and guanosine 5'-monophosphate (GMP) on the antitumor activity of 5'-deoxy-5-fluorouridine (5'-DFUR) was investigated using P388 leukemia and P815 mastocytoma. The antitumor activity of 5'-DFUR was markedly enhanced by coadministration of inosine or guanosine. The increase in lifespan (ILS) of mice treated with 5'-DFUR was augmented by the combination with guanosine or inosine in a dose-dependent fashion, and the maximum ILS was about 160% with the combination, while that in the case of 5'-DFUR alone was only 48% in the P388 leukemia system. The therapeutic ratio (dose at ILSmax/dose at ILS30) of the combination with guanosine or inosine was 333 and 136, respectively, whereas that of 5'-DFUR alone was 3.6. GMP also markedly potentiated the antitumor activity of 5'-DFUR in both P388 leukemia and P815 mastocytoma systems, just as it potentiated the activity of 5-fluorouracil in the latter system. The uric acid level in the serum was elevated after IP injection of guanosine or inosine but the value was much lower in the case of guanosine than in inosine.

Interleukin-1 from P388D1: effects upon neutrophils, plasma iron, and fibrinogen in rats, mice, and rabbits

Partially purified interleukin-1 was prepared from the murine cell line P388D1. This interleukin-1 produced fever in rabbits and the amount required to cause an increase of 1 degree C was determined. This dose of interleukin-1 produced neutrophilia when injected into rats and rabbits but not in mice, and increased plasma iron and fibrinogen in all three species. Although the mouse was a poor responder to murine interleukin-1 for neutrophilia, it responded unusually well for increasing plasma fibrinogen.