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Biomedical subjects

J B de Sousa

Publications and source records attributed to J B de Sousa.

2 recordsLinked to original sources

A new optimization based approach to experimental combination chemotherapy.

A new approach towards the design of optimal multiple drug experimental cancer chemotherapy is presented. Once an adequate model is specified, an optimization procedure is used in order to achieve an optimal compromise between after treatment tumor size and toxic effects on healthy tissues. In our approach we consider a model including cancer cell population growth and pharmacokinetic dynamics. These elements of the model are essential in order to allow less empirical relationships between multiple drug delivery policies, and their effects on cancer and normal cells. The desired multiple drug dosage schedule is computed by minimizing a customizable cost function subject to dynamic constraints expressed by the model. However, this additional dynamic wealth increases the complexity of the problem which, in general, cannot be solved in a closed form. Therefore, we propose an iterative optimization algorithm of the projected gradient type where the Maximum Principle of Pontryagin is used to select the optimal control policy.

Drug Therapy, Combination↗

Effects of diclofenac sodium on intestinal anastomotic healing. Experimental study on the small intestine of rabbits.

To study the possible effects of diclofenac sodium on intestinal anastomoses, 48 rabbits were submitted to surgery consisting of two single-layer ileal anastomoses performed with separate propylene 5-0 sutures. The animals were divided at random into two groups (test and control). The animals in the test group were given intramuscular injections of diclofenac sodium at the dose of 3 mg/kg body weight at 24-hour intervals, and the control animals were given injections of an identical amount of 0.9 percent saline. The animals were sacrificed on the 3rd, 7th, and 14th postoperative days for macroscopic evaluation of the peritoneal cavity and of the anastomoses, tensile strength measurement, hydroxyproline determination, and histopathologic examination. The following results were observed: anastomotic dehiscence followed by peritonitis and death in five test animals (20.83 percent) and no control animals; decreased anastomotic tensile strength on the 7th day in test animals (P less than 0.05); delayed acute inflammatory response and onset of fibroblast proliferation in the test group; and similar hydroxyproline levels in both groups. On the basis of the results obtained, we conclude that diclofenac sodium had a negative effect on intestinal anastomotic healing.

Anastomosis, Surgical↗