An improved apparatus for blood perfusion of the canine cerebral vasculature

An improved perfusion apparatus is described which consists of a membrane oxygenator, roller pump, reservoir, heat exchanger, blood filter, and inert tubing. Heparinized blood may be used and is delivered at flow rates from 10 to 250 ml/min. Dogs are anesthetized with halothane and their cerebral arterial blood supply isolated by the method of Gilboe et al. (8). When the canine brain is perfused for 5 hr using the described apparatus, the rates of cerebral oxygen and glucose consumption are 5.19±0.12 ml/100 g/min and 39.9±6.5 mol/100 g/min, respectively. Of the total glucose consumed by the brain, about 1/4 is contributed by the erythrocytes. An equivalent of about 9% of the consumed glucose is returned to the blood as lactate. Electron microscopic examination of cerebral cortex samples reveals no differences between 5-hr perfused brain and appropriate nonperfused controls. It is concluded that the apparatus is a useful system for organ perfusion and that the canine brain perfused by this method remains physiologically and metabolically active for at least 5 hr.With the technical assistance of Evelyn Townsend.     

Advancement in soil microcosm apparatus for biogeochemical research

Application of soil microcosms has largely improved our understanding in biogeochemical processes, because all major environmental factors can be independently controlled. Recent advancement to improve the performance of soil microcosm has been made. The modifications include using a different incubation vessel and cap, replacing a magnetic stirrer with an overhead stirrer, providing temperature control for the microcosm, using data logger for continuous measurements of redox potential (Eh), pH and temperature, and applying automatic gas analysis. The modifications can be made in any combination to suit an individual's needs and budget.     

A new apparatus and surgical technique for the dual perfusion of human tumor xenografts in situ in nude rats

We present a new perfusion system and surgical technique for simultaneous perfusion of 2 tissue-isolated human cancer xenografts in nude rats by using donor blood that preserves a continuous flow. Adult, athymic nude rats (Hsd:RH-Foxn1(rnu)) were implanted with HeLa human cervical or HT29 colon adenocarcinomas and grown as tissue-isolated xenografts. When tumors reached an estimated weight of 5 to 6 g, rats were prepared for perfusion with donor blood and arteriovenous measurements. The surgical procedure required approximately 20 min to complete for each tumor, and tumors were perfused for a period of 150 min. Results showed that tumor venous blood flow, glucose uptake, lactic acid release, O(2) uptake and CO(2) production, uptake of total fatty acid and linoleic acid and conversion to the mitogen 13-HODE, cAMP levels, and activation of several marker kinases were all well within the normal physiologic, metabolic, and signaling parameters characteristic of individually perfused xenografts. This new perfusion system and technique reduced procedure time by more than 50%. These findings demonstrate that 2 human tumors can be perfused simultaneously in situ or ex vivo by using either rodent or human blood and suggest that the system may also be adapted for use in the dual perfusion of other organs. Advantages of this dual perfusion technique include decreased anesthesia time, decreased surgical manipulation, and increased efficiency, thereby potentially reducing the numbers of laboratory animals required for scientific investigations.