Biomedical subjects

E L Gillette

Publications and source records attributed to E L Gillette.

111 records · Page 7Linked to original sources

PubMedDate not supplied

Effects of intraoperative hyperthermia on peripheral nerves: neurological and electrophysiological studies.

The tolerance of peripheral nerves to heat may limit the heat dose which can be applied to tumours. This may be particularly important in intraoperative hyperthermia (IOHT) for pelvic and retroperitoneal tumours. Furthermore the effects of hyperthermia alone must be known before its effects can be assessed in combination with irradiation. In this study injury to sciatic nerves was evaluated in 30 beagle dogs for 1 year following IOHT. IOHT was performed using a water circulating hyperthermia device with multichannel thermometry system. Neurological and electrophysiological examinations were done before, during and after IOHT treatment. Electrophysiological examinations showed a significant decrease in sciatic nerve conduction velocity and potential amplitude immediately after 60 min of heating for all temperatures. The greatest decrease in conduction velocity was observed for a temperature of 45 degrees C. Full recovery of nerve conduction velocity was observed 3 weeks following hyperthermia for all dogs except for those exposed to 45 degrees C. Neurological findings correlated with electrophysiological results. All five dogs which had nerve exposed to 45 degrees C for 60 min had severe neurological changes, with recovery taking place between 3 and 11 months after treatment. Based on these results it appears that temperatures to the peripheral nerve exceeding 44 degrees C for 1 h are likely to cause significant, but not necessarily permanent, nerve injury.

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PubMedDate not supplied

Effects of intraoperative hyperthermia on canine sciatic nerve: histopathologic and morphometric studies.

Failure to achieve local control in the treatment of pelvic and retroperitoneal tumours results in a high rate of recurrences. The objective of intraoperative hyperthermia (IOHT) is to enhance the effect of intraoperative radiation therapy and to increase local tumour control. The tolerance of peripheral nerves to heat may limit the heat dose that can be applied to tumours. Histopathologic and histomorphometric changes of canine sciatic nerve after 60-min IOHT were studied in three groups of five dogs each for temperatures of 43, 44 and 45 degrees C. IOHT was performed using a water-circulating hyperthermia device with a multichannel thermometry system on surgically exposed sciatic nerve. Histopathologic and histomorphometric studies were done immediately, 3 weeks and 12 months after IOHT. Histologic changes observed immediately after treatment were minimal but at 3 weeks following 60-min 45 degrees C IOHT both axon and myelin loss and an increase in endoneurial fibrous tissue were observed. Twelve months after treatment a statistically significant decrease in axon, myelin and small vessel percentages as well as an increase in endoneurial and epineural connective tissue were observed for dog treated to 45 degrees C. Dog treated to 44 degrees C for 60 min had similar statistically significant but less severe changes. Twelve months after 43 degrees C IOHT for 60 min, nerve fibres appeared normal and endoneurial connective tissue was only increased mildly around small and medium-sized vessels. These results suggest that temperatures to the peripheral nerve > 44 degrees C for 60 min are likely to cause significant histopathologic changes that can be found 12 months after treatment. A hypothesis of the mechanism of heat injury to peripheral nerves was developed.

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PubMedDate not supplied

Phase I evaluation of mitoxantrone alone and combined with whole body hyperthermia in dogs with lymphoma.

The maximum tolerated dose of mitoxantrone (MX) administered alone or combined with whole body hyperthermia (WBH) was determined in this nonrandomized, prospective study in dogs with lymphoma. MX was administered to 53 dogs every three weeks for a total of six treatments unless progressive disease or persistent, severe toxicity developed. Fifty dogs were evaluable (MX alone n = 30, MX/WBH n = 20). MX was administered as a 1 h infusion at the onset of the plateau phase of WBH in dogs treated with combined therapy. Dogs were evaluated weekly between treatments for the first four treatments with physical examination and complete blood counts to define acute and cumulative toxicity. Dogs were evaluated every three weeks for tumour response until relapse. The maximum tolerated dose (MTD) was defined as that dose in each group that resulted in a 50% incidence of moderate or severe toxicity as estimated from logistic regression analysis of the toxicity data. Myelosuppression was the only toxicity observed. Neutropenia was equal in frequency and severity between treatment groups. Thrombocytopenia was not observed in any dog receiving MX/WBH but occurred in 13% of dogs treated with MX alone. The MTD for MX +/- WBH was 6.1 +/- 0.6 and 6.5 +/- 0.8mg/M2 respectively. A steeper dose response relationship was observed in dogs receiving combined therapy compared to dogs treated with MX alone suggesting WBH may improve the uniformity of patient response to chemotherapy. We concluded that MX may be administered without dose reduction to dogs undergoing WBH and that MX should be evaluated more thoroughly in future thermochemotherapy studies.

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