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J D Chapman

Publications and source records attributed to J D Chapman.

At least 73 records · Page 4Linked to original sources
PubMed1987

Is misonidazole binding to mouse tissues a measure of cellular pO2?

Misonidazole (MISO), a hypoxic cell radiosensitizer, forms covalently-linked adducts to cellular molecules as a result of bioreductive metabolism, a process which is strongly dependent upon oxygen concentration. MISO binding to liver tissue taken from air-breathing mice was three to five times greater than binding to other normal tissues. The relative binding of [14C]MISO to various mouse tissue cubes in vitro was measured by autoradiography as a function of defined oxygen concentrations, and standard curves (binding rate vs oxygen concentration) were generated. The oxygen concentration for half-maximum binding as well as the maximum and minimum binding rates (grains per 100 micron 2) observed for liver tissue were not significantly different from those measured for brain or heart tissue. These results, along with previously published data on MISO binding to isolated hepatocytes in vitro, suggest that the elevated binding to liver in vivo may result, in part, from the organ existing at a significantly lower pO2 than other normal tissues. They also suggest that this drug adduct procedure could be developed as a sensitive method for the quantitative measurement of tissue pO2 at the cellular level.

Animals↗
PubMed1987

Growth of murine bone marrow under various oxygen conditions in media buffered with HEPES.

Increased plating efficiencies were observed for marrow granulocyte-macrophage precursor cells (CFU-gm) cultured in an experimental system at reduced gas-phase oxygen concentrations. However, only a small component of this increase was attributable to decreased oxygen. The changed media buffering system was the more dominant factor contributing to increased plating efficiency, suggesting that other factors in addition to a reduction in oxygen may influence clonogenicity.

Animals↗
PubMed1987

The effectiveness of cis-platinum, cyclophosphamide and melphalan in treating disseminated tumor cells in mice.

Both B16 melanoma and Lewis lung carcinoma growing in C57/Bl mice spontaneously metastasize to the lungs and other organs. When the tumors are grown in the mouse tail to a specific volume and amputated, the spontaneously disseminated tumor cells can then be independently treated. The effects of a single dose of cyclophosphamide (200 mg/kg), cis-platinum (6 mg/kg) and melphalan (10 mg/kg) on the appearance of pulmonary and other metastases were measured. The cis-platinum treatment was shown to reduce the number and incidence of metastases of both tumors at various times after treatment. The antimetastatic effectiveness of cis-platinum against these two tumors was increased when 2.4 mg/kg was administered each day for five consecutive days after amputation of the primary. Cyclophosphamide, when administered at two-thirds maximum tolerated dose, had a small promoting effect on the number and incidence of pulmonary metastases of Lewis lung carcinoma, whereas, applied in the same dose, it had efficacy in the treatment of disseminated B16 melanoma and inhibited appearance of both pulmonary and lymph-node metastases. When melphalan was administered in single- and multiple-dose regimens, the number and incidence of metastases of both tumors increased at various times after primary tumor amputation. These data suggest that melphalan can promote the growth of disseminated tumor cells in both the lungs and other sites and that some systemic chemotherapies may result in promotion instead of suppression of metastatic disease.

Cisplatin↗
PubMed1986

In vitro binding of 14C-misonidazole to hepatocytes and hepatoma cells.

The binding rate of 14C-Misonidazole was determined for freshly isolated mouse hepatocytes, mouse hepatoma cells, EMT-6 tumor cells, and V79 Chinese hamster lung fibroblasts. At 10 microM drug concentration, the four different cell lines bound 14C-Misonidazole at rates of 12.4, 29.9, 51.6, and 13.5 pmoles/10(6) cells/hr, respectively. This relative order of binding was observed over a drug concentration range of 10-100 microM. These data indicate that in extreme hypoxia, mouse hepatocytes do not bind 14C-Misonidazole at a uniquely high rate in vitro, compared to other normal and tumor cell lines. This observation suggests that the increased binding to liver in vivo observed by other investigators is due to the liver existing at a reduced oxygen tension, compared to other normal tissues.

Animals↗
PubMed1986

Binding of 3H-misonidazole to solid human tumors as a measure of tumor hypoxia.

Treatment-resistant, chronically hypoxic tumor cells have been assumed to exist in some solid human tumors, limiting their curability. To date, six patients with different types of tumors have been studied using radioactive labelled electron affinic compounds that bind to hypoxic cells. Although the gross clinical appearance of the tumors in all six patients was of a large and fixed mass which might on clinical grounds be expected to contain hypoxic cells, we have observed drug binding to hypoxic regions in only two, a rapidly growing small cell lung cancer (SCLC) and a malignant melanoma. The hypoxic fraction of the malignant melanoma was found to be 6% and the SCLC tumor approximately 10%. We have observed that areas of maximum adduct formation can be found in tumor cells immediately adjacent to blood vessels, suggesting that blood flow over the labelling interval was restricted. These preliminary studies suggest that sensitizer adduct formation in human tumor tissue may be a useful measure of tissue pO2 at the cellular level and that tumor hypoxia might be more related to the rate of tumor growth and histological grading than to tumor size.

Autoradiography↗
PubMed1986

A novel technique for measuring human tissue pO2 at the cellular level.

Some electron-affinic drugs, developed as hypoxic cell radiosensitizers, become selectively bound to the molecules of hypoxic cells by metabolism. This technique has been used to identify zones of chronically hypoxic cells in multicellular spheroids and animal tumours. Tritiated-misonidazole was administered to a patient with advanced melanoma 22 h prior to the surgical resection of a large metastatic s.c. lesion growing on the face. Autoradiographic analysis of histological sections revealed zones of intense labelling by the radioactive drug, indicative of tumour cells which were chronically hypoxic. This technique appears to provide an indirect measurement of tissue pO2 at the cellular level from which estimates of the tumour hypoxic fraction can be made. These data are encouraging as regards the development of 'sensitizer-adduct' procedures for the invasive and non-invasive measurement of hypoxia in both tumours and normal tissues.

Adult↗
PubMed1986

The treatment of animal tumours and their metastases with 4-hydroxyanisole.

4-Hydroxyanisole (4-OHA) was administered to C57Bl/10J mice in which B16 melanoma or Lewis lung carcinoma had been implanted s.c. or i.m. The drug had the largest antitumour effect against B16 melanoma growing s.c. and a smaller antitumour effect against B16 melanoma or Lewis lung carcinoma growing i.m. In the treatment regimens where drug was administered only after tumour implantation, a significant reduction in number of spontaneous metastases and their incidence was observed. Again, the largest antimetastatic effect was observed for s.c. B16 melanoma with smaller effects observed for i.m. B16 melanoma or Lewis lung carcinoma. Experiments in which 4-OHA treatment was initiated after amputation of the primary tumour implanted in the tail confirmed that 4-OHA did have antitumour activity against disseminated tumour cells. The drug regimens studied to date produced significant delays in the appearance of spontaneous metastases in the lungs and significant increases in the life spans of the treated animals.

Animals↗
PubMed1986

The in vitro sensitivities to radiation and misonidazole of mouse bone marrow cells derived from different microenvironments.

Previous studies had indicated that haematopoietic cells (CFU-GM) which reside within compact bone are resistant to ionizing radiation and sensitive to the cytotoxic action of misonidazole (MISO) relative to cells which reside within the core of mouse femurs. It was postulated that the microenvironment within compact bone might be relatively hypoxic. CFU-GM from femur cores (Fraction 1) and from compact bone (Fraction 3) have been exposed to ionizing radiation and to the hypoxic cell radiosensitizer, MISO, under controlled conditions of oxygenation in vitro. The inherent radiosensitivity of aerated Fraction 1 CFU-GM is similar to their in vivo radiosensitivity. An oxygen enhancement ratio of 2.2 is observed for these cells in vitro. On the other hand, the in vitro radiosensitivity of hypoxic Fraction 3 CFU-GM was similar to their in vivo radiosensitivity. The oxygen enhancement ratio for Fraction 3 cells was 1.5, significantly lower than that observed for Fraction 1 cells. When CFU-GM cells were exposed to MISO under hypoxic conditions in vitro it was found that Fraction 3 CFU-GM were more sensitive to its cytotoxic action than were cells from Fraction 1. These data are consistent with the interpretation that some CFU-GM reside in an environment of relative hypoxia within the compact bone of the mouse femur.

Animals↗
PubMed1986

Treatment of Dunning R3327-AT rat prostate tumors with photodynamic therapy in combination with misonidazole.

Fischer X Copenhagen rats bearing Dunning R3327-AT tumors were treated with hematoporphyrin derivative and red light (630 nm from an argon-driven dye laser) alone or in combination with the hypoxic cell radiosensitizer, misonidazole (MISO). In vitro studies had suggested that hypoxia might significantly decrease the cytotoxicity of photodynamic therapy (PDT) and labeling with [14C]MISO had revealed a significant fraction of viable hypoxic cells in this tumor. PDT alone resulted in a growth delay of 8.8 days but no tumor cures were observed. The administration of MISO (i.p. at 0.5 mg/g) 33 min prior to PDT resulted in an average growth delay of 15.2 days and tumor cures (local control at 33 days) in 20% of animals treated. If MISO at a similar dosage was administered 30 min after PDT an average growth delay of 16.3 days was measured and tumor cure was observed in 70% of the animals treated. These results suggest that the hypoxic cell fraction in R3327-AT tumors might be a limitation to their curability by PDT. The addition of MISO and/or other hypoxic cell cytotoxic agents to PDT procedures may provide an effective means of treating PDT-resistant hypoxic cells in solid tumors.

Animals↗
PubMed1986

Iodoazomycin riboside (1-(5'-iodo-5'-deoxyribofuranosyl)-2-nitroimidazole), a hypoxic cell marker. I. Synthesis and in vitro characterization.

Misonidazole (MISO), a selective radiosensitizer of hypoxic cells, forms adducts with cellular biomolecules with rates which are 30-50 X higher under hypoxic as compared to aerobic conditions of incubation. This technique of sensitizer adduct formation was proposed as a possible means of measuring the hypoxic fraction of solid tumors by noninvasive procedures. Iodoazomycin riboside (5'-IAZR) and 5'-[125I]AZR were synthesized and chemically characterized. Measurements of in vitro cytotoxicity and radiosensitizing ability with EMT-6 tumor cells in vitro indicated that 5'-IAZR is approximately 3 X more toxic and effective than is azomycin riboside (AZR) and approximately 10 X more toxic and effective than is MISO. 5'-[125I]AZR was shown to selectively bind to hypoxic EMT-6 cells at rates which were 2.5-3 X faster than those of MISO. The absolute rates of binding of 5'-IAZR to hypoxic cells at concentrations of 10-100 microM are the highest observed in this laboratory for any hypoxic cell radiosensitizer tested to date. These data suggest that 5'-IAZR, when labeled with an appropriate radioisotope (e.g., 131I), might be a useful marker for hypoxic cells in solid tumors amenable to noninvasive detection. Additional studies with animal tumor models appear to be warranted.

Animals↗
PubMed1985

The radiation sensitivities of R3327-H and R3327-AT rat prostate adenocarcinomas.

Dunning R3327-H and R3327-AT tumors growing subcutaneously in the flanks of Fischer X Copenhagen rats were irradiated with 137Cs gamma-rays at volumes of approximately 300 mm. The effects of various doses of radiation were estimated by measurements of subsequent tumor growth as well as by histological evaluation. The well-differentiated, hormonally-responsive R3327-H tumor was more radiosensitive than the anaplastic R3327-AT tumor. The reasons for this increased radiation sensitivity of the R3327-H tumor include a greater "apparent" radiation sensitivity of tumor cells and the absence of tumor hypoxia. The presence of hypoxic tumor stem cells was inferred from significant radiosensitization of tumor growth delay by 0.5 mg./gm. misonidazole and by a technique which utilizes radioactively-labelled misonidazole as a marker for hypoxic cells. The persistence of a mass of R3327-H tumor tissue after aggressive radiotherapy was not indicative of tumor cells. Furthermore, the rapid increase in volume of R3327-AT cells after aggressive radiotherapy was attributed to limited proliferation of tumor cells which were destined to ultimately die. Possible implications of these findings for the management of human prostatic adenocarcinoma are discussed.

Adenocarcinoma↗
PubMed1984

The detection and measurement of hypoxic cells in solid tumors.

The presence of viable hypoxic cells in human cancers has concerned oncologists for years. Cells in tissues that are deficient in oxygen are relatively resistant to radiation inactivation and may not be accessible to some systemic chemotherapy. The premise that hypoxic tumor cells do, indeed, control the radiocurability of some cancers is supported by some clinical evidence. The presence of hypoxic regions within tumors can be directly and indirectly inferred from invasive procedures such as oxygen electrode techniques and histologic study, respectively, but such information does not significantly contribute to current prescriptions given by oncologists for tumor treatment. Novel procedures (some of which are noninvasive) for detecting hypoxic regions within solid tumors have been proposed and are based upon two recent developments: (1) the discovery that some radiosensitizing drugs become selectively bound by metabolism to the molecules of viable hypoxic cells, and (2) the growing availability of new imaging procedures based upon positron-emission tomography, single-photon emission tomography, and nuclear magnetic resonance spectroscopy. Preliminary research results from these novel procedures are reviewed, and the potential clinical impact of each is discussed.

Anaerobiosis↗
PubMed1984

Evaluation of diethyldithiocarbamate as a radioprotector of bone marrow.

The radioprotective action of DDC on normal hematopoietic tissue in mice was evaluated. An increase in CFU-S and CFU-GM in DDC treated unirradiated control mice was consistently observed. When post-irradiation survival of CFU-S and CFU-GM from DDC treated animals was normalized to account for this observed increase, protection factors ranging from 0.9 to 1.6 were observed. These protection factors are significantly lower than those reported by others. Maximum radioprotection was observed when irradiations were performed 15 to 30 min after DDC treatment; maximum increase in GFU-GM occurred within one to two hr following treatment. The increase in CFU-GM is analogous to that observed in animals treated with endotoxin, a non-thiol radioprotector. When C3H/HeJ mice, which are genetically incapable of responding to endotoxin, were challenged with DDC, an average CFU-GM increase of 1.7 times was observed, suggesting that the stimulatory effects of DDC were not due to endotoxin contamination. DDC was administered daily for three days before irradiation and little or no increase in CFU-GM and no radioprotection was observed, suggesting that the marrow can become refractory to DDC. When WR-2721 was tested in similar studies, a dose-modifying radioprotection was observed, with no significant non-specific stimulation of hematopoietic cells.

Animals↗
PubMed1984

Electron-affinic compounds for labelling hypoxic cells: the synthesis and characterization of 1-[2-(2-iodophenoxy)-ethyl]-2-nitroimidazole.

Highly lipophilic and protein-bound derivatives of 1-(2-phenoxy-ethyl)-2-nitroimidazole (PENI; RGW-609), a known radiosensitizer, have been prepared by introducing one (IPENI) and two (DIPENI) iodine atoms into the phenyl ring via electrophilic substitution. The electron affinity of all 3 compounds, as determined by differential pulse polarography, was similar to that for MISO, a radiosensitizer which has undergone clinical trial, but P values were 2-3 orders of magnitude greater that for MISO and %PB values were as high as 30% in vitro compared to less than 1% for MISO. 131I-PENI was prepared by catalysed halogen exchange with Na131I in greater than 90% yield, and was found to be chemically and radiochemically stable in solution for at least 2 weeks. Whole-body studies in BDF/1 mice bearing EMT-6 tumors showed rapid hepatic extraction and biliary elimination with little or no accumulation in any other tissue including tumor and fat, indicating that P and % PB values had little impact on in vivo distribution and disposition. 131I-PENI was not measurably deiodinated in vivo. IPENI and DIPENI are radiosensitizers by inference only, that is, they have not been tested for radiosensitizer properties. However, PENI, the parent compound, has been shown to be active as a radiosensitizer, and the peak potentials (polarographic) for both IPENI and DIPENI fall near those of MISO, PENI and most other 2-nitroimidazole sensitizers. The low levels of concentration in target tissues achieved by 131I-PENI mitigate against its use as a diagnostic agent.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗