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J van der Zee

Publications and source records attributed to J van der Zee.

98 records · Page 6Linked to original sources
PubMedDate not supplied

Effect of hyperthermia on the central nervous system: a review.

Experimental data show that nervous tissue is sensitive to heat. Animal data indicate that the maximum tolerated heat dose after local hyperthermia of the central nervous system (CNS) lies in the range of 40-60 min at 42-42 x 5 degrees C or 10-30 min at 43 degrees C. No conclusions concerning the heat sensitivity of nervous tissue can be derived from clinical studies using localized hyperthermia. The choice whether or not to exceed the critical heat dose, as derived from laboratory studies, in clinical practice is very much dependent on the clinical situation such as the anatomical site and volume of the tissue involved, and prior therapy. Data on clinical application of whole body hyperthermia (WBH) show that nervous tissue can withstand a slightly higher heat dose than after localized heating, which might be the result of developing thermal resistance during treatment. Expression of thermotolerance was observed in the spinal cord of laboratory animals. After WBH in man at a maximum between 40 and 43 degrees C for 6 h-30 min CNS complications were reported, but other complications seemed to be more life-threatening. Most studies indicate that impairment of the CNS after WBH was not due to direct heat injury to the brain or spinal cord, but was secondary as a result of physiological changes. Heat, at least if applied shortly after X-rays, enhances the response of nervous tissue to radiation. Neurotoxicity of chemotherapeutic drugs does not seem to be a limiting complication in hyperthermia if combined with chemotherapy, but only few data are available. The limited clinical experience shows that safe hyperthermic treatment of CNS malignancies or tumours located close to the CNS seems feasible under appropriate technical conditions with adequate thermometry and taking the sensitivity of the surrounding normal nervous tissue into account.

Animals↗
PubMedDate not supplied

Quality control of the SIGMA applicator using a lamp phantom: a four-centre comparison.

An elliptical phantom with a fat-equivalent ring and lamp matrix was developed for observing the power distribution in ring applicators used for regional hyperthermia. This phantom was used on four European BSD-2000-type therapy systems under routine conditions to test the quality of the SIGMA-60 applicator (systems in Berlin, Essen, Munich and Rotterdam). Frequency-dependent focusing imbalances were observed in all systems. At the time of the quality control test two of the systems displayed considerable errors in their settings. The system setups and possible ways of correcting errors are described in detail. Small maladjustments are caused by coupling effects between antennas and their surroundings and by interactions between the coaxial cables which supply the power. Serious distortions can be caused by phase errors and defects in cables or plugs; the latter can result in significant long-term restrictions on the ability to control the SAR (specific absorption rate) distribution in a way the user may not notice. The measurements gained from these four systems confirm the need for a practical and universal procedure for quality control in regional hyperthermia.

Europe↗
PubMedDate not supplied

Temporary vascular occlusion and glucose: effects on tumour and normal tissue pH in animal experiments.

The relationship between duration of a period of vascular occlusion and magnitude of pH decrease in tumour and normal tissue was investigated in rats. To acidify tissue pH further, moderate dose glucose (2.4-3.0 g.kg(-1).hr(-1)) was administered intravenously through a catheter positioned in a tail vein, immediately after the clamp was released. This sequence of pH modifying modalities was chosen since it is employed in clinical regional isolation perfusion for recurrence of malignant melanoma of the limbs. Tumour pH in rat rhabdomyosarcoma BA1112 decreased more than normal tissue pH under 10, 20, 30 or 60 min of temporary vascular occlusion. Administration of glucose following any period of clamping always decreased tumour pH further. The largest pH decrease (0.29 pH units) was obtained after 30 min of clamping followed by 60 min glucose and 60 min saline infusion. In the clinic the combination of a maximum of 30 min of clamping followed by moderate dose glucose infusion, which can decrease tumour pH effectively, can be easily achieved in the setting of regional isolation perfusion. It can be used for treatment modalities that are known to be enhanced at lowered tissue pH, such as hyperthermia and certain chemotherapeutic drugs. These results form the basis for studying the therapeutic gain which can be obtained with this model.

Animals↗
PubMedDate not supplied

Intraspinal temperatures during regional deep hyperthermia induced by electromagnetic radiation in the Macaca mulatta.

A capacitive ring system operating at 27 MHz was tested for temperature distribution in the abdominal cavity of the living Rhesus monkey. Catheters were introduced through the abdomen and their location checked after the experiment. During two of these experiments a catheter was also introduced into the intraspinal canal. Temperature distribution was rather homogeneous within the abdominal cavity. Core temperature remained 3-5 degrees C below intra-abdominal temperatures. The intraspinal temperature increase was of the same magnitude compared with intra-abdominal temperature increase. Similar findings in other species have been reported by others. It is concluded that during non-invasive induction of regional hyperthermia by electromagnetic radiation, where a high level of energy is directed close to the spine, the intraspinal temperatures may be increased as high as the temperatures within the surrounding tissues. The central nervous system may be relatively sensitive to hyperthermia and hyperthermia may sensitize the spinal cord to radiation. Therefore, when hyperthermia is targeted at areas near the spine, either alone or in combination with radiotherapy applied to the tolerance limit of the spinal cord, these findings will have to be taken into consideration.

Abdomen↗
PubMedDate not supplied

A 433 MHz Lucite cone waveguide applicator for superficial hyperthermia.

The effective field size (EFS, SAR > or = 50% of the maximum SAR at 1 cm depth) of a conventional 433 MHz water filled waveguide applicator (32 cm2, aperture area 100 cm2) has been increased by: (1) replacement of the two diverging brass side walls which are parallel to the direction of the electric field by Lucite walls; and (2) Placement of a heterogeneous permittivity in the centre of the aperture. SAR distributions were measured at several depths in layered fat-muscle phantoms. With Lucite side walls the SAR distribution becomes wider in the H-plane of the aperture, resulting in a circular SAR distribution. In this situation the EFS is 67 cm2. Additional insertion of a PVC cone with a top angle of 15 degrees at the centre of the aperture increases the EFS to 91 +/- 6 cm2 for a waterbolus of 18 x 18 x 1 cm3. The experiments also demonstrated that the resulting EFS is affected by the waterbolus size and shape. Calorimetric measurements showed that the efficiency of the improved applicator is comparable to the efficiency of the conventional water filled waveguide applicator, 50 and 56% respectively. The modifications reported provide a simple and inexpensive means to increase the EFS and can be easily implemented in water filled waveguide applicators.

Breast Neoplasms↗
PubMedDate not supplied

Hyperthermia may decrease the development of telangiectasia after radiotherapy.

CASE REPORT: A patient with recurrent breast cancer was reirradiated twice on adjacent fields with a time interval of 9 months. The first time she was treated with reirradiation alone, the second time with reirradiation plus hyperthermia. The reirradiation schedule for both fields was 8 x 4 Gy in 4 weeks. Both fields overlapped partly with the field of postoperative radiotherapy, which was applied 57 and 66 months earlier to a total dose of 40.5 Gy. RESULTS: During the 52 to 61 months follow-up, a remarkable difference in telangiectasia development, between the parts of the reirradiation fields overlapping with the primary radiotherapy field, became apparent. Telangiectasia was observed 9 months after treatment with reirradiation alone and progressed to confluent in 47 months after treatment. In the reirradiation plus hyperthermia area, the maximum observed telangiectasia was slight until 52 months after treatment. DISCUSSION: The difference in the development of telangiectasia between these fields cannot be explained by differences in any of the known radiation treatment related prognostic factors. A protective effect by hyperthermia has been suggested by Haveman and coworkers, who have shown experimentally that heat treatment leads to enhanced proliferation of endothelial cells, thereby inducing a fast repopulation and replacement of X-ray damaged cells. CONCLUSION: This difference in telangiectasia formation is an interesting observation. Whether such a protective effect of hyperthermia is of general relevance has to become clear from more extensive clinical studies.

Breast Neoplasms↗
PubMedDate not supplied

Comparison between the use of whole blood versus a diluted perfusate in regional isolated perfusion by continuous monitoring of transcutaneous oxygen tension: a pilot study.

In 12 successive women (median age, 58 [39-89] years) who were treated with regional isolated perfusion for melanoma of the lower extremities, peroperative continuous monitoring of the transcutaneous oxygen tension (PtcO2) was performed as an indicator for tissue oxygenation and (sub)cutaneous perfusion. Regional perfusion started using whole blood as perfusate with a hematocrit of 40.7 +/- 4.9. After 40 min of drug circulation the perfusate was diluted to a hematocrit of 25.3 +/- 4.9, a value usually applied in perfusion. Flow rates (mean 51.2 +/- 14.4 mL/min/L perfused tissue) were kept at a level that caused no systemic leakage and no more than 10-cm increase above starting venous pressure. Oxygen supply was set at one half of the flow of the perfusate (in mL/min). The mean PtcO2 during the first part of perfusion, in which seven patients could achieve preperfusion levels for at least some of the time, was significantly higher than during the last part, in which no patient reached the preperfusion level (30.8 mm Hg vs 23.5 mm Hg; p = .0019). The mean maximal decrease in PtcO2 after dilution was 21.3 +/- 11.6 mm Hg. Venous blood gases of the perfusate also deteriorated after dilution. Two patients encountered a grade III and two a grade IV toxicity reaction after perfusion. We conclude that increasing the hematocrit of the perfusate to physiologic levels by using whole blood can guarantee a physiologic tissue oxygenation at relatively low flow rates. However, physiologic tissue oxygenation on its own is not enough to prevent toxicity after perfusion.

Adult↗