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M N Gaze

Publications and source records attributed to M N Gaze.

At least 37 records · Page 2Linked to original sources
PubMed1995

No-carrier-added iodine-131-MIBG: evaluation of a therapeutic preparation.

UNLABELLED: Iodine-131-metaiodobenzylguanidine ([131I]MIBG) is a radiopharmaceutical for imaging as well as targeted radiotherapy of neuroblastoma. It is predicted that the use of no-carrier-added [131I]MIBG, rather than the conventional low specific activity preparation, will result in an enhanced therapeutic ratio because of different transport processes in neuroblastoma compared with most normal tissues. METHODS: The main aims of the study were: (1) to determine whether [131I]MIBG of substantially greater specific activity is transported into tumor cells by the same process as the existing compound; (2) to evaluate the effect of nonradiolabeled MIBG on the cytotoxicity of no-carrier-added [131I]MIBG; and (3) to compare the biodistribution of both preparations of the radiochemical in neuroblastoma xenografts. RESULTS: Active uptake of no-carrier-added [131I]MIBG was temperature-, sodium- and oxygen-dependent; ouabain- and desmethylimipramine-inhibitable; and could be blocked competitively by monoamine inhibitors of the noradrenaline transport mechanism. The rank order of specific uptake capacity in a panel of neuroblastoma cell lines was the same for both low and high specific activity drug. Neuroblastoma spheroid regrowth was 85% inhibited by no-carrier-added [131I]MIBG at 2 MBq.ml-1. Inhibitory potency was reduced in a dose-dependent manner by nonradiolabeled MIBG. The accumulation of no-carrier-added [131I]MIBG was significantly greater in tumor, adrenal, heart and skin of tumor-bearing mice than that of the conventional therapy preparation of [131I]MIBG. CONCLUSION: These data indicate that there may be clinical advantages in the use of no-carrier-added [131I]MIBG rather than conventional [131I]MIBG.

3-Iodobenzylguanidine↗
PubMed1994

Differential intracellular processing of the anthracycline drug ME2303 in doxorubicin-sensitive (A2780) and -resistant (A2780AD) human ovarian cancer cells as studied with confocal laser scanning microscopy and image analysis.

Laser scanning confocal microscopy has been used to follow the uptake and efflux of the 2-fluoroglycoside of doxorubicin, ME2303, in live cultures of the human ovarian cancer cell line A2780 and its doxorubicin-resistant variant A2780AD. Our methods combine confocal laser scanning microscopy and image analysis to examine the dynamics of anthracycline drugs in cancer cells. Cytotoxicity determined by MTT dye reduction showed that A2780AD cells were more than 400 times less sensitive to doxorubicin compared to A2780 cells but almost 9 times more sensitive to ME2303 compared to doxorubicin. The naturally fluorescent drug was tracked within live cells at 37 degrees C to provide time-course information in relation to nuclear and Golgi-associated cellular domains, as indicated by BODIPY FL ceramide-associated fluorescence. In both cell types, ME2303 was characterised by strong nuclear membrane and perinucleolar fluorescence and as a localised punctate pattern within the nucleus. A2780AD cells accumulated ME2303 in their nuclei at a much reduced rate compared to the doxorubicin-sensitive cells, and ME2303 efflux from resistant cell nuclei was approximately twice as fast as from A2780 cells. The relative uptake of ME2303 into Golgi-associated domains and the nucleus were monitored simultaneously during the initial 35 min of exposure to 10 microM ME2303 and during the first 45 min of a "chase" culture following exposure to 20 microM ME2303. ME2303 was detectable within the Golgi-associated domains of A2780 cells several minutes later and in less relative concentration than in A2780AD cells 15 min into a chase culture. Our results suggest the direct involvement of differences in drug processing via the Golgi apparatus in the expression of P-glycoprotein-related drug resistance.

Coloring Agents↗
PubMed1994

N-myc gene copy number in neuroblastoma cell lines and resistance to experimental treatment.

The N-myc oncogene is amplified in approximately 30% of neuroblastomas. It is well established that cases of neuroblastoma with amplified N-myc have markedly poorer prognosis than those in which N-myc copy number is not elevated. The mechanism for this association is not known but may be related to cellular resistance to radiation or cytotoxic drugs. Seven human neuroblastoma cell lines were used to investigate the relationship between N-myc copy number or expression and sensitivity to ionising radiation and to cisplatin. N-myc copy number was assessed by Southern blotting and hybridisation using the p-Nb1 probe. The signal produced by DNA from the cell lines was compared with that of single copy N-myc from normal human placental DNA. A range of N-myc copy numbers from 1 to 800 was found. Expression levels of N-myc mRNA were compared by "dot blotting" and subsequent hybridisation to the p-Nb1 probe. Radiosensitivity was assessed by surviving fraction at 2 Gy (SF2) following 60Co gamma irradiation. Values ranged from 0.13 to 0.52. Sensitivity to cisplatin was indicated by comparison of isoeffective concentrations (concentration required to produce 1 log cell kill). These ranged from 7.5 to 13 microM. Cisplatin studies showed a correlation between N-myc copy number (though not expression) and resistance to this drug. If this relationship is causal it may explain why treatment fails in those patients with an elevated N-myc copy number. However, no correlation was found between N-myc copy number or expression and sensitivity to radiation. It is possible that N-myc amplification confers resistance to some but not all treatments used in the therapy of neuroblastoma. Further investigations along these lines may lead to the identification of agents which are most appropriate for the treatment of neuroblastoma with amplified N-myc gene.

Blotting, Southern↗
PubMed1994

Combination chemotherapy for primitive neuroectodermal and other malignant brain tumours.

The toxicity and efficacy of a chemotherapy schedule comprising vincristine and cyclophosphamide, alternating with carboplatin and etoposide, has been assessed in a group of 15 patients with medulloblastoma, supratentorial primitive neuroectodermal tumours (PNET) or other malignant brain tumours. The patients comprised four adults and 11 children. Chemotherapy was given for palliation of recurrent disease (six patients), as an adjuvant to radiotherapy and surgery in five poor prognosis patients, or to delay the need for radiotherapy in four children aged 2 years or less. The treatment was generally well tolerated, with the principal toxicity being myelo-suppression. Among the ten assessable patients, there were six complete responders and one partial, an overall response rate of 70%. Three patients had progressive disease. Responses, although associated with good symptomatic improvement, were short lived, with two patients relapsing while still receiving chemotherapy. Three of four very young children relapsed within 7 months of completing chemotherapy and then received radiotherapy. It is concluded that this schedule merits further evaluation and comparison with more protracted and toxic schedules.

Adolescent↗
PubMed1994

Prediction of accumulation of 131I-labelled meta-iodobenzylguanidine in neuroblastoma cell lines by means of reverse transcription and polymerase chain reaction.

Radiolabelled meta-iodobenzylguanidine (mIBG) currently provides one of the most promising options for targeted radiotherapy of neuroblastoma. No means currently exists for prediction of mIBG uptake in tumour cells of individual patients other than semiquantitative inferences from diagnostic scanning which depend on the continued existence of a macroscopic tumour mass. A biological rapid assay which could be applied at initial biopsy would be invaluable in selecting patients for therapeutic strategies which incorporate radiolabelled mIBG. We have assessed the expression of the noradrenaline transporter gene in six human neuroblastoma cell lines and in three non-neural crest-derived cell lines using reverse transcription followed by the polymerase chain reaction. Transcription of this gene was observed in five out of six neuroblastoma cell lines but in none of the control cells. A highly significant correlation was established (P < 0.01) between gene expression and active cellular accumulation of mIBG. It is suggested that semiquantitative evaluation of noradrenaline transporter gene transcripts may be predictive of mIBG uptake by tumours in vivo.

3-Iodobenzylguanidine↗
PubMed1994

Modification of meta-iodobenzylguanidine uptake in neuroblastoma cells by elevated temperature.

Successful imaging or treatment of neuroblastoma with 131I-meta-iodobenzylguanidine (131I-mIBG) depends on the selectivity of active (type 1) uptake of mIBG in neuroblastoma cells relative to passive (type 2) uptake present in most normal tissues. This study investigates the effects of moderately elevated temperature (39-41 degrees C) on the cellular uptake of 131I-mIBG in two neuroblastoma cell lines [SK-N-BE(2c) and IMR-32] and in a non-neuronal (ovarian carcinoma) cell line (A2780). In SK-N-BE(2c), a cell line with high active uptake capacity, the specific (type 1) uptake was reduced by 75% (P < 0.001) at 39 degrees C. Both IMR-32 and A2780 have a low capacity for accumulation of mIBG by active uptake. These cell lines demonstrated a statistically significant increase in accumulation at 39 degrees C, mainly as a result of increased non-specific transport. At 41 degrees C uptake of 131I-mIBG was reduced in all cell lines. Thus, the active component of mIBG uptake is more vulnerable to increased temperature than the passive component. It seems probable that moderately increased temperature will have an unfavourable effect on the therapeutic differential for targeted radiotherapy of neuroblastoma using radiolabelled mIBG.

3-Iodobenzylguanidine↗
PubMed1994

Carrier-free 131I-meta-iodobenzylguanidine: comparison of production from meta-diazobenzylguanidine and from meta-trimethylsilylbenzylguanidine.

Meta-iodobenzylguanidine (MIBG) is a drug which is selectively accumulated by the uptake-1 process in adrenergic tissues. When labelled with 131I, it may be used for the targetted radiotherapy of tumours such as phaeochromocytoma and neuroblastoma. This paper describes the preparation of carrier-free 131I-MIBG by radioiodination of meta-diazobenzylguanidine, and compares this process with one involving iododesilylation of meta-trimethylsilylbenzylguanidine. Both processes result in the formation of carrier-free 131I-MIBG whose specific activity at greater than 3 x 10(16) Bq mol-1 is at least 100 times higher than that of commercially available 131I-MIBG for therapeutic use. The therapeutic use of 131I-MIBG with a higher than usual specific activity is predicted to result in a greater target-to-nontarget ratio, and therefore enhanced efficacy because of an increased therapeutic index. As the radiochemical yield of the process involving the metadiazobenzylguanidine intermediate is only 13%, compared with 98% for the iododesilylation reaction, the latter is the preferred synthetic route.

3-Iodobenzylguanidine↗
PubMed1994

Pharmacokinetics and efficacy of 131I-meta-iodobenzylguanidine in two neuroblastoma xenografts.

The pharmacokinetics, biodistribution and efficacy of the radiopharmaceutical 131I-meta-iodobenzylguanidine (131I-mIBG) were determined in murine xenografts of two human neuroblastoma cell lines, SK-N-SH and SK-N-BE(2c). These lines have similar capacities in vitro for active uptake of 131I-mIBG, but different radiobiological characteristics. Groups of four mice were killed after injection of 131I-mIBG, and retained radioactivity in the tumour and normal tissues was measured at 8, 16, 24 and 48 h. Within each type there was heterogeneity of tumour uptake, although average values were similar for both. The per cent injected dose per gram of tumour retained at 24 h was (mean and 95% confidence interval) 0.95 (0.67-1.23) for SK-N-SH and 0.76 (0.47-1.05) for SK-N-BE(2c). The growth of tumours in groups of seven animals following injection of 35, 70 or 105 MBq 131I-mIBG was compared with that of controls. The specific regrowth delay (median and 95% confidence intervals) caused by 105 MBq 131I-mIBG was 4.2 (0.9-5.9) in SK-N-SH and 5.6 (0-11.3) in SK-N-BE(2c) bearing mice. SK-N-BE(2c) xenografts were significantly more sensitive to external beam irradiation than SK-N-SH xenografts.

3-Iodobenzylguanidine↗
PubMed1993

The nature of the head and neck cancer.

Squamous cell carcinoma of the head and neck is a disease predominantly of males and is due to a variety of known environmental irritants, notably cigarette smoke. Dietary, viral and immunological factors may also be relevant. Head and neck squamous cancers express epidermal growth factor receptors and some show weak levels of oestrogen receptor activity, but a reliable serum marker of tumour burden remains to be identified. The prognosis is found to be less favourable in females, in those with advanced T stage, in association with multiple node involvement, especially where extracapsular spread is present and where the T4/T8 ratio is elevated. Administration of heterologous blood during therapy may also have an adverse effect on prognosis. Interested clinicians must remember that most cases are preventable.

Biomarkers, Tumor↗
PubMed1993

Lung abscesses mimicking multiple pulmonary metastases.

Five patients receiving chemotherapy for cancer through Hickman central venous catheters had lung lesions detected by plain chest radiography or computed tomography. In each case these were initially misdiagnosed as metastases, although they ultimately proved to be staphylococcal abscesses. Because of the grave implications of an erroneous diagnosis of metastatic malignant disease, clinicians are urged to consider abscesses in the differential diagnosis of radiological chest abnormalities in such patients.

Adolescent↗
PubMed1993

Third L. H. Gray Workshop, Kelvin Conference Centre, University of Glasgow, Scotland, 24-25 March 1992: The radiobiology of targeted radiotherapy.

Thirty-five participants from eight countries attended the third workshop sponsored by the L. H. Gray Trust (with additional funding from the Cancer Research Campaign). The forum was a unique opportunity to bring together clinicians and scientists with a variety of backgrounds to discuss the biological targeting of therapeutic radiation.

Humans↗
PubMed1992

131I-meta-iodobenzylguanidine therapy in neuroblastoma spheroids of different sizes.

Mathematical models have predicted that targeted radiotherapy of neuroblastoma with metaiodobenzylguanidine (mIBG) is less likely to cure small rather than large micrometastases if 131I is the conjugated radionuclide. This study uses multicellular tumour spheroids as an in vitro model to test the hypothesis that smaller tumours of sub-millimetre dimensions are relatively resistant to 131I-mIBG. Spheroids of the human neuroblastoma cell line SK-N-BE(2c), either 250 microns or 400 microns diameter, were incubated with 131I-mIBG at concentrations of up to 6.0 MBq ml-1. Using both regrowth delay and spheroid 'cure' as endpoints, the greater vulnerability of larger spheroids was confirmed. From this in vitro result we conclude that when used in vivo 131I-mIBG may spare smaller micrometastases. Therefore, either a radionuclide such as 211At which emits a shorter path length radiation should be conjugated to mIBG, or targeted radiotherapy should be combined with a treatment such as total body irradiation, the efficacy of which is not reduced in smaller tumours.

3-Iodobenzylguanidine↗
PubMed1992

Routine nasopharyngeal biopsy in adult secretory otitis media.

This study was to determine whether routine examination under anaesthesia and nasopharyngeal biopsy in adults presenting with deafness due to secretory otitis media (SOM) is necessary for detection of nasopharyngeal malignancy. Two patient groups were studied. The first comprised 72 adults with SOM. Of these patients, 3 had nasopharyngeal tumours, 2 of whom also had cervical lymphadenopathy. The prevalence of malignancy in patients with SOM but no other suspicious signs was 1/72 (1.4%). The second group comprised 66 patients receiving treatment for nasopharyngeal neoplasms. In this group, 8 patients had SOM at presentation, 7 of whom had other features suspicious of malignancy. SOM as the sole presenting feature of nasopharyngeal malignancy was 1/66 (1.5%). EUA and biopsy of the nasopharynx is a cost effective investigation which continues to be indicated in adults presenting with deafness due to SOM.

Adolescent↗
PubMed1992

Salvage laryngectomy after radical radiotherapy for laryngeal carcinoma.

Of 376 patients who were treated by radical radiotherapy for squamous carcinoma of the larynx, 56 subsequently underwent total laryngectomy. Residual or recurrent tumour was identified in 43 of the resection specimens, and necrosis alone in 13 cases, although a positive biopsy had been obtained in 3 of these prior to salvage laryngectomy. No disease related factors such as site or stage of the original tumour, or treatment related factors such as radiation type or dose, were found to be predictive of whether or not tumour was present. The clinical opinion of an experienced surgeon was found to have a positive predictive value of 0.86 for the presence of tumour. The fistula rate of salvage laryngectomy, 15 out of 56, was similar to that of other series. The actuarial cause specific 5-year survival for patients with tumour was 0.589, and for patients with necrosis only was 0.923. Intercurrent, smoking related disease was the cause of death in 16 of the 33 patients who have died.

Biopsy↗
PubMed1992

The use of parallel EEL spectral imaging and elemental mapping in the rapid assessment of anti-cancer drug localization.

Both electron spectroscopic imaging (ESI) and electron energy-loss spectroscopy (EELS) have great potential for use in several areas of cancer research. In biologically targeted radiotherapy, cytotoxic drug therapy and boron neutron capture therapy the effectiveness of many drugs is often critically dependent upon the intracellular localization of the agent employed. We describe the use of parallel EEL spectral imaging to assess the penetration and location of the iodine-containing drug meta-iodobenzyl guanidine, of potential value in targeted radiotherapy, and for the rapid detection of boron within borate-adsorbed polystyrene beads, of potential value in boron neutron capture therapy. We also describe elemental mapping of boron following low-temperature embedding. These results show how the techniques could be applied to many forms of cancer research by discussing the validity and limitations of the techniques experimentally. We also provide an outline of other areas in this field which could benefit from the future application of ESI and EELS.

3-Iodobenzylguanidine↗
PubMed1992

Stage IB cervical carcinoma: a clinical audit.

All patients with FIGO Stage IB cervical cancer registered with the Department of Clinical Oncology at the Western General Hospital, Edinburgh, during the 6 years from 1979 to 1984 have been reviewed, as part of a continuing programme of clinical audit. Of the 140 patients with Stage IB disease, 68 (49%) were treated by primary surgery of whom 44 (31%) also received adjuvant radiotherapy. Radical radiotherapy was the definitive treatment for 69 patients (49%). Three patients (2%) were not treated with curative intent. The crude 5-year survival rate for all cases was 72% and the cause-specific 5-year survival rate was 78%. Local tumour control at 5 years was 72%. There was no significant difference in outcome between the surgically treated and irradiated groups of patients. Age, histology and nodal status did not influence outcome. Irradiated patients with bulky tumours fared significantly worse than the other patients who received radical radiotherapy. Multivariate analysis of all patients revealed no significant independent prognostic variables. Primary surgery appears to confer no benefit over radical radiotherapy in terms of either survival or local control. Treatment-related late bladder and bowel morbidity was, however, significantly worse in irradiated patients.

Adult↗