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Biomedical subjects

J F Gross

Publications and source records attributed to J F Gross.

At least 55 records · Page 3Linked to original sources
PubMed1979

Tissue perfusion inhomogeneity during early tumor growth in rats.

Tissue perfusion in BA 1112 sarcomas of WAG inbred Rijswijk rats was determined from in vivo measurements of capillary density, length, and erythrocyte velocity in modified Algire chamber preparations. Studies were done with the use of television techniques in situ during a period of 26 days, both in control chambers and after implantation of a 0.1-mm3 piece of tumor tissue. Perfusion in control areas void of tumor tissue. Perfusion in control areas void of tumor was approximately 8-10 ml/minute/100 g of tissue. Flow in active tumor growth regions on the outward side of the tumor edge was through undifferentiated channels and had characteristics of flow through a porous medium. Despite enhanced arterial supply, the stabilized tumor microcirculation at the inward side of the growing tumor retained its perfusion rate constant (15-18 ml/min/100 g). Perfusion in central portions of the tumor was about 2-4 ml/minute/100 g during 12 days, whereas the tumor doubled in diameter. Our findings support the concept of temporal and functional blood flow inhomogeneity in the microcirculation of spreading tumors.

Animals↗
PubMed1978

Prediction of adriamycin disposition in cancer patients using a physiologic, pharmacokinetic model.

A ten-compartment flow-limited pharmacokinetic model scaled from rabbit tissue distribution data was used to predict plasma adriamycin concentrations in 23 patients and adriamycin tissue uptake in nine surgery patients following iv bolus doses of 10--60 mg/m2. The predicted concentrations were compared to experimentally determined adriamycin using a specific thin-layer chromatographic fluorescence scanning procedure. The predicted plasma time course for 11 of 16 patients with relatively normal liver and kidney function agreed closely with the observed plasma time course. Deviations in the other five patients were ascribed to possible changes in the profile of metabolite formation and/or fluctuations in biliary clearance. All four patients with elevated serum bilirubin demonstrated significantly higher and more prolonged plasma levels than predicted. The results of two patients with impaired kidney function and one patient with both hepatic and renal involvement were inconclusive. The comparison between predicted and observed tissue concentrations in biopsy samples was varied; however, all were within an order of magnitude. It is concluded that the model depicts adriamycin uptake and distribution reasonably well; however, more needs to be known concerning individual variation in metabolic and biliary excretion rates for this to become more patient-specific. Also, a tumor compartment appears to be an important addition in modifying the model to allow for clinical utility.

Animals↗
PubMed1977

Mathematical model for cyclocytidine pharmacokinetics.

The pharmacokinetics of the drug cyclocytidine in humans were modeled by using a physiological and anatomical approach. Each pertinent tissue is represented by a single compartment, and these compartments are linked together by the circulatory system. Each compartment is then represented by an ordinary differential equation that represents the rate of change in drug concentration as function of convecting transport, metabolism, and urinary clearance. The models for cyclocytidine and cytarabine are linked together by a hydrolysis term in each equation set. The resulting equation sets are then solved numerically to predict the concentration of both drug species in situ. The models use physiological blood flows, tissue volumes, and clearance parameters. The results of the model show that cyclocytidine can act as a reservoir for cytarabine in vivo over the time studied. This effect is confined to relatively long times and relatively low plasma concentrations.

Ancitabine↗