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Biomedical subjects

J C Miller

Publications and source records attributed to J C Miller.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

Preclinical safety testing of DISC-hGMCSF to support phase I clinical trials in cancer patients.

BACKGROUND: DISC-hGMCSF is a gH-deleted HSV-2 based vector expressing human GM-CSF that is being developed for cancer immunotherapy. To support first clinical use, a range of preclinical safety studies were performed using DISC-hGMCSF in addition to DISC-murine-GMCSF and the backbone vector, TA-HSV. METHODS: The toxicity of the DISC vectors was assessed by repeated dose, neurovirulence and neuroinvasiveness studies in mice, and by safety studies in rabbits, guinea pigs and athymic nude mice. Studies were also conducted to determine whether the vector could establish latency in local ganglia in mice following intradermal injection, and whether it could reactivate from the latent state. The vector biodistribution following intravenous administration was also investigated in mice, using PCR to detect vector DNA. RESULTS: The DISC vectors were essentially non-toxic in all the systems studied. No adverse reactions were seen in mice receiving four intravenous doses of DISC-mGMCSF and the results from studies of neurovirulence, neuroinvasiveness, local tolerance in rabbit, general safety in mice and guinea pigs and safety in athymic nude mice were consistent with DISC being unable to replicate and cause disease. The vector could establish latency in local ganglia in mice, but at low efficiency, and could not reactivate infectious virions. Following intravenous administration, vector DNA was widely distributed up to Day 28, but by Day 56 had disappeared from gonads and brain and was only found in blood and liver. CONCLUSION: The panel of safety studies provided evidence that DISC-hGMCSF will be unable to replicate and cause disease, and has low toxicity in man. These data were presented to the Medicines Control Agency and the Gene Therapy Advisory Committee as part of the regulatory submissions for a clinical trial in melanoma patients. These submissions have been approved, and DISC-hGMCSF has now entered a phase I clinical trial in the UK by direct intratumoural injection.

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PubMedDate not supplied

Pharmacological differentiation of kainate receptors on neonatal rat spinal motoneurones and dorsal roots.

The objectives of this study, conducted on neonatal rat spinal cord and dorsal roots in vitro, were to characterise the actions of a range of willardiine analogues on GluR5-containing kainate receptors present in dorsal roots, to determine whether GluR5-containing receptors are also present on motoneurones, and to differentiate responses mediated by kainate receptors from those mediated by AMPA receptors on motoneurones. (S)-5-Trifluoromethyl-willardiine, (S)-5-iodowillardiine, (S)-5-iodo-6-azawillardiine and ATPA were found to be potent agonists of kainate receptors on dorsal roots (EC50 values 0.108 +/- 0.002, 0.127 +/- 0.010, 0.685 +/- 0.141 and 1.3 +/- 0.3 microM, respectively) being more potent but of lower efficacy than kainate (EC50 value 14.8 +/- 1.8 microM). (S)-5-Iodo-6-azawillardiine blocked kainate-induced depolarisations of the dorsal root, probably via its desensitising action. Kainate-induced responses of dorsal roots were weakly antagonised by (RS)-3,5-dicarboxyphenylglycine (DCPG) (apparent KD 1.5 +/- 0.4 mM). Kainate receptors containing GluR5 subunits do not appear to be present on motoneurones since (RS)-3,5-DCPG (1 mM) potentiated rather than antagonised kainate-induced depolarisations of motoneurones. Although (S)-5-iodowillardiine (a potent and selective agonist at GluR5-containing kainate receptors) depolarised motoneurones (EC50 value 5.8 +/- 0.6 microM), such depolarisations were antagonised by both (RS)-3,4- and (RS)-3,5-DCPG, which are selective AMPA receptor antagonists at motoneurones, showing a KD value of 73 microM (Schild slope, 0.96 +/- 0.09) and an apparent KD value of 123 +/- 38 microM, respectively. This accords with the previously reported activity of willardiine analogues at AMPA receptors. Since neither (RS)-3,4- nor (RS)-3,5-DCPG antagonised kainate-induced motoneuronal depolarisations but cyclothiazide enhanced and GYK153655 blocked these responses it is possible that a component of the kainate response may be mediated by a population of DCPG-insensitive AMPA receptors on motoneurones. However, it is also possible that a population of kainate receptors other than those containing GluR5 subunits, are responsible for these effects. The new compounds introduced in this study are likely to be useful tools for studying the physiological role of kainate receptors in CNS function.

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PubMedDate not supplied

Regional cerebral palmitate incorporation following transient bilateral carotid occlusion in awake gerbils.

[14C]Palmitate was injected intravenously in awake gerbils at various times after 5 minutes of bilateral carotid artery occlusion or a sham operation. Regional rates of incorporation of plasma palmitate into the hippocampus and other regions of the anterior circulation were determined relative to the mean rate of incorporation into regions of the posterior circulation using quantitative autoradiography and a ratio method of analysis. One day after bilateral carotid occlusion, relative palmitate incorporation was elevated significantly by 16% in the CA4 pyramidal cell layer and by 20% in the dentate gyrus of the hippocampus compared with sham-operated gerbils. At 3 days, significant elevations of this magnitude were found in the CA3 and CA4 cell layers, whereas relative incorporation was reduced by 26% in the CA1 pyramidal cell layer. At 7 days, the only significant difference from control was a 15% elevated incorporation in the CA3 pyramidal cell layer. Histologic examination indicated substantial cell death in the CA1 pyramidal layer at 3 days, with extensive glial reaction and phagocytic invasion at 7 days. Our results suggest that the turnover of palmitate-containing lipids is reduced in the CA1 layer of the gerbil hippocampus but that lipid synthesis is stimulated in hippocampal regions (CA3, CA4, dentate gyrus) affected by but recovering from transient bilateral carotid occlusion.

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PubMedDate not supplied

Altered membrane fluidity occurs during metabolic impairment of cardiac myocytes.

The purpose of this study was to evaluate the effect of impaired high energy phosphate metabolism on the membrane fluidity of cardiac myocytes. Cultured neonatal rat cardiac myocytes were treated with the metabolic inhibitor, iodoacetic acid (IAA) (30 microM). Membrane lipid fluidity was assessed by the steady-state fluorescence polarization of 1,6-diphenyl 1-1,3,5-hexatriene (DPH). Metabolic inhibition with IAA resulted in a progressive decrease in fluorescence polarization and calculated microviscosity. Microviscosity was decreased by 11% after 60-90 minutes and by 21% after 120-210 minutes, respectively. These changes are consistent with a progressive increase in membrane fluidity. Pretreatment with the experimental phospholipase inhibitor, U26, 384 (5-10 microM) resulted in a slower onset and less change in membrane fluidity after treatment with IAA. Thus, a) metabolic inhibition in cardiac myocytes induces prominent alterations in membrane fluidity which probably contribute to the membrane dysfunction accompanying myocardial injury and b) phospholipid degradation may be a significant factor in the genesis of altered membrane fluidity.

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