Histological and immunohistochemical changes after transurethral balloon laser hyperthermia in the canine prostate

New experimental model for single liver lobe hyperthermia in small animals using non-directional microwaves

PURPOSE

Our aim was to develop a new experimental model for in vivo hyperthermia using non-directional microwaves, applicable to small experimental animals. We present an affordable approach for targeted microwave heat delivery to an isolated liver lobe in rat, which allows rapid, precise and stable tissue temperature control.

MATERIALS AND METHODS

A new experimental model is proposed. We used a commercial available magnetron generating 2450 MHz, with 4.4V and 14A in the filament and 4500V anodic voltage. Modifications were required in order to adjust tissue heating such as to prevent overheating and to allow for fine adjustments according to real-time target temperature. The heating is controlled using a virtual instrument application implemented in LabView® and responds to 0.1° C variations in the target. Ten healthy adult male Wistar rats, weighing 250-270 g were used in this study. The middle liver lobe was the target for controlled heating, while the rest of the living animal was protected.

RESULTS

In vivo microwave delivery using our experimental setting is safe for the animals. Target tissue temperature rises from 30°C to 40°C with 3.375°C / second (R2 = 0.9551), while the increment is lower it the next two intervals (40-42°C and 42-44°C) with 0.291°C/ s (R2 = 0.9337) and 0.136°C/ s (R2 = 0.7894) respectively, when testing in sequences. After reaching the desired temperature, controlled microwave delivery insures a very stable temperature during the experiments.

CONCLUSIONS

We have developed an inexpensive and easy to manufacture system for targeted hyperthermia using non-directional microwave radiation. This system allows for fine and stable temperature adjustments within the target tissue and is ideal for experimental models testing below or above threshold hyperthermia.

Signaling for the caspases: their role in prostate cell apoptosis

PURPOSE

The caspases are an evolutionary conserved family of cell death proteases. Their activation during apoptosis is an important underlying theme in prostate cancer therapy. We summarize the signaling pathways leading to the recruitment of the caspases and address the importance of recent therapeutic strategies aimed at specifically targeting these proteases in relation to prostate cancer.

MATERIALS AND METHODS

We present a background introduction into the role of the caspases in apoptosis and how failure to signal effectively their activation may contribute to prostate cancer progression. Key studies aimed at specifically targeting the caspases as cancer therapy are discussed.

RESULTS

Prostate carcinogenesis and apoptosis are related. The deregulation of apoptosis contributes to tumor initiation, metastasis and progression to the androgen insensitive state. Conversely the effectiveness of therapy often depends on its ability to induce apoptosis in prostate cancer cells. Identifying abnormalities in the apoptotic signaling pathway has greatly contributed to understanding the biology of prostate cancer. Elucidating caspase regulation has contributed to the design of novel therapies for prostate cancer.

CONCLUSIONS

We summarize the physiological and pathological pathways leading to caspase activation in the prostate and describe novel approaches that target these proteases.