Bruce Ng

Partial hepatectomy accelerates local tumor growth: Potential roles of local cytokine activation

BACKGROUND Surgical excision of liver tumors represents the only curative treatment for primary and metastatic liver malignancies. It has been suspected that hepatectomy may stimulate growth of microscopic tumors. To determine whether local or systemic factors after hepatectomy are responsible for enhancement of tumor growth, the effects of hepatectomy on the experimental growth of liver or pulmonary tumors were examined. METHODS One hour after injection of 10(6) Morris hepatoma cells into either the portal or femoral vein, which produces isolated liver and lung tumors, respectively, animals were randomized to undergo 0%, 30%, or 70% partial hepatectomy (PH). RESULTS Animals that underwent portal injection of tumor had significantly increased liver tumor burden after PH (sham, 25 +/- 7 vs PH, 94 +/- 17; p < 0.01), whereas animals that underwent femoral injection had no change in lung tumor burden after PH. PH was associated with significantly increased levels of transforming growth factor-alpha, transforming growth factor-beta, and basic fibroblast growth factor in the liver but not in the lung. CONCLUSIONS Changes in liver cytokine-growth factor activation may contribute to enhanced tumor growth in the liver after hepatectomy.

Isolated single-lung perfusion with TNF-α in a rat sarcoma lung metastases model☆

Abstract We conducted a trial of isolated lung perfusion using tumor necrosis factor (TNF) in an experimental sarcoma lung metastasis model. In an in vitro experiment, methylcholanthrene-induced sarcoma cells were incubated for 48 hours with 42 μg/mL of either human or murine TNF. Controls were incubated with Hanks balanced salt solution. In an in vivo experiment, 23 F344 rats were injected with 10 7 methylcholanthrene-induced sarcoma cells. On day 7, 4 animals were perfused with 210 μg of murine TNF, 5 animals were perfused with 420 μg of murine TNF, 10 animals underwent isolated lung perfusion with 420 μg of human TNF, and 4 animals were injected systemically with 420 μg of human TNF. Animals were sacrificed on day 14 and the lung nodules counted. The cells incubated with murine TNF exhibited a 21% decrease in growth ( p = 0.07); cells incubated with human TNF showed a 37% decrease in growth ( p P = 0.07). Animals perfused with 420 μg/mL of human TNF had 21.7 ± 18.3 nodules on the left lung and 91.7 ± 66.2 nodules on the right lung ( p

Isolated single-lung perfusion: A study of the optimal perfusate and other pharmacokinetic factors

BACKGROUND Isolated single-lung perfusion with doxorubicin hydrochloride was shown to be effective in clearing experimental sarcoma lung metastases in the rat. The best perfusate to be used for isolated lung perfusion and factors affecting the final lung concentration of doxorubicin are the subject of the present study. METHODS In experiment 1, 60 animals were randomized to undergo isolated left lung perfusion with doxorubicin with six different perfusates (n = 10 per group): saline, low-potassium-dextran, 5% albumin, 6% hetastarch, 5% buffered albumin, and 6% buffered hetastarch. Five animals served as negative controls. After perfusion, the lung wet to dry ratio and final lung doxorubicin concentration were determined. In experiment 2, 60 animals underwent isolated left lung perfusion with either 80 micrograms/mL or 320 micrograms/mL of doxorubicin. Animals were perfused at either 0.5 mL/min or 1 mL/min and for 2, 6, or 10 minutes. At the end of the perfusion period, the left lung doxorubicin concentration was measured. Statistical analysis included analysis of variance, the Duncan test for multiple comparisons, and multiple linear regression analysis. Significance was defined as a p value of less than 0.05. RESULTS In experiment 1, perfusion with 6% buffered hetastarch resulted in the lowest lung wet to dry ratio, significantly different from all groups except the controls. Perfusion with low-potassium-dextran solution led to the highest final lung concentration of doxorubicin. In experiment 2, a model to predict final lung doxorubicin concentration was constructed: Log (final lung concentration) = 1.9 + 0.0071.P + 0.186.T, where P is the measured perfusate concentration of doxorubicin, and T is the time of perfusion in minutes. The R2 was 0.91 and p, less than 0.001. The dose of doxorubicin per kilogram of animal body weight, the dose of doxorubicin per square meter of body surface area, the total amount of doxorubicin delivered, and the rate of perfusion did not meet the criteria to enter the equation. CONCLUSIONS Isolated lung perfusion experiments should use 6% buffered hetastarch as the perfusate. The perfusate doxorubicin concentration and the duration of perfusion are the only factors determining the final lung concentration of doxorubicin. In lung perfusion experiments, the dose of chemotherapy is not as important as the perfusate concentration and the duration of the perfusion. Animals should be perfused at a lower rate so the lungs are exposed to less doxorubicin without changing the final lung concentration.

Effect of growth hormone on tumor and host in an animal model

Background: The relative effects of growth hormone on tumor versus host growth and protein metabolism are not known. This study examines the influence of recombinant rat growth hormone (r-rGH) on host and tumor growth, host body composition, and protein synthesis of tumor and host in tumor-bearing rats.Methods: After left flank implantation of methylcholanthrene-induced sarcoma, 28 Fischer rats with palpable tumor were treated with s.c. saline or 1 mg/kg/day r-rGH for 11 days. At death, fractional protein synthetic rates (FSRs) of tumor, liver, and gastrocnemius muscle were determined. In a separate experiment, 27 tumor-bearing rats received saline or 1 mg/kg/day r-rGH for 2 weeks. Tumor and host growth and host body composition were analyzed.Results: Animals treated with r-rGH had significantly higher liver FSR than did controls (233 ± 27%/day vs. 110 ± 4%/day, respectively). No significant differences were associated with growth hormone administration with respect to tumor growth, host composition, or FSR of tumor or muscle.Conclusions: Growth hormone stimulates liver protein synthesis, without changing tumor growth, protein synthesis, or host composition in this rat sarcoma model. Further investigation of growth hormone as an anticachectic agent is warranted.

Establishment of an Experimental Intrapulmonary Tumor Nodule Model

BACKGROUND A pulmonary tumor model is necessary to study the biology and therapy of lung cancer. Methods to establish a solitary intrapulmonary nodule are not well defined. Two methods for solitary intrapulmonary tumor nodule development in the Fischer rat are described. METHODS Methylcholanthrene-induced sarcoma cell suspensions were introduced into lung parenchyma of Fischer rats via limited thoracotomy and lung puncture, or instilled into a distal airway after tracheal puncture and catheterization. Intrapulmonary tumor location, implantation mortality, procedure length, and animal survival were recorded. RESULTS Single pulmonary nodules developed at the implanted position in 100% (n = 320) and 95% (62/65) of animals after direct injection into the pulmonary parenchyma or via tracheal puncture and instillation. Operative mortality was 2% and 5% via lung or tracheal implantation, respectively. Less than 5 minutes was required for each implantation. Mean survival time was 24 +/- 2 and 26 +/- 6 days after lung or tracheal implantation in animals allowed to survive until tumor-induced death. CONCLUSIONS These easily performed, reproducible methods of establishing solitary intrapulmonary tumors are useful tools for lung cancer research.