Purpose: This study investigates the effect of constitutively raised interstitial fluid pressure on osteosarcoma physiology and chemosensitivity.Experimental Design: We did pressure and blood flow assessments at the time of open biopsy in patients with the diagnosis of high-grade osteosarcoma and correlated this to survival and chemotherapy-associated tumor necrosis. Osteosarcoma cell lines were then evaluated for proliferative and therapeutic indices in a replicated high-pressure environment.Results: Sixteen osteosarcomas in vivo were assessed and exhibited elevated interstitial fluid pressures (mean 35.2 F F SD, 18.6 mmHg). This was not associated with significantly impeded blood flow as measured by a Doppler probe at a single site (P < < 0.12). Nonetheless, greater chemotherapyassociated necrosis and associated longer survival were seen in tumors with higher interstitial fluid pressures (P < < 0.05).In vitro, cells undergo significant physiologic changes under pressure. Osteosarcoma cell lines grown in a novel hydrostatically pressurized system had variable cell linespecific growth proportional to the level of pressure. They were more proliferative as indicated by cell cycle analysis with more cells in S phase after 48 hours of pressurization (P < < 0.01). There was a significant elevation in the cell cycle -related transcription factors E2F-1 (P < < 0.03) and E2F-4 (P < < 0.002). These changes were associated with increased chemosensitivity. Cells tested under pressure showed an increased sensitivity to cisplatin (P < < 0.00006) and doxorubicin (P < < 0.03) reminiscent of the increased chemotherapy-associated necrosis seen in tumors with higher interstitial fluid pressure in the clinical study.Conclusions: The results of this study suggest that cells in the in vivo pressurized environment are at a higher state of regenerative activity than is demonstrable in conventional cell culture systems. Variations in tumor interstitial fluid pressure have the potential to alter chemotherapeutic effects.

Midazolam causes dose-related changes in rCBF in brain regions associated with the normal functioning of arousal, attention, and memory.

Antineoplastic and antiresorptive drugs added to polymethylmethacrylate cement may prevent local cancer progression and failure of reconstructive devices used to treat patients with pathologic fractures. We tested the mechanical properties of cement containing various amounts of the drugs and found that as much as 2 g of either doxorubicin or pamidronate can be added to Simplex cement and the cement retains 87% of its compressive and tensile strength after 6 months of wet storage. Approximately 1 mg pamidronate elutes from experimental pellets. One half of the drug elution occurs within the first day in experiments that combined doxorubicin and pamidronate, and within 3 days when pamidronate was the only additive. Cement containing these drugs seems to be strong enough, but its fatigue strength should be tested before using it clinically. Sufficient amounts of the tested drugs elute to have potential biologic activity.

Elevated interstitial fluid pressure (IFP) is observed in most solid tumors. However, the study of the cellular processes of tumors and the development of chemotherapy are routinely studied using in vitro culture systems at atmospheric pressure. Using a new pressurized cell culture system, we investigated the influence of hydrostatic pressure on population dynamics of three primary osteosarcoma (HOS, U2OS, SaOS2) and two metastatic tumor cell lines (MCF7 breast, H1299 lung) that invade bone. Values of IFP in normal human bone and muscle, and in osteosarcoma tumors obtained during their surgical biopsy established the hydrostatic pressure range for the in vitro cell studies. The IFP values were obtained from a retrospective review of patient records. IFP from confirmed osteosarcoma was 35.9+/- 16.2 mmHg. Tumor IFP was significantly higher than muscle IFP (p < 0.001) and bone IFP (p < 0.003). The in vitro study measured the cell-line proliferation using hydrostatic pressures of 0, 20, 50 and 100 mmHg. The findings suggest that hydrostatic pressure either increases or decreases tumor proliferation rates depending on cell type. Furthermore, cell death was not associated with apoptosis.