Perfusion systems

Fig. 7.3. The total Loc-I-Gut concept. Left a perfusion system of the duodenal segment. Center a tube system with double balloons which allow a segmental single-pass perfusion of jejunum. Right a perfusion system of the small intestinal stomi.

Shen, B., Greenfield, P., and Reid, S., Calcium Alginate Immobilized Hybridomas Grown Using a Fluidized-Bed Perfusion System with a Protein-Free Medium, Cytotechnol., 14 109 (1994)... 

Yamahara H, Suzuki T, Mizobe M, Noda K, Samejima M (1990) In situ perfusion system for oral mucosal absorption in dogs. J Pharm Sci 79 963-967... 

A range of experiments can characterize LGICs that are expressed in Xenopus oocytes. Application of a drug solution into the perfusion system allows for exposure of the oocyte to that concentration of ligand. In these studies, it is usually assumed that the bath volume is relatively small and that there is minimal dead-space in the flow tubing. 

The use of large-scale automated perfusion systems has allowed for several oocytes to be tested in parallel and presents an opportunity for high-throughput drug screening. For example, the Robooctye system (see... 

Schnizler et al., 2003) permits the automation of both cRNA injection and two-electrode voltage clamp recordings from multiple oocytes in standard 96-well plates. Although the cost and maintenance of such an apparatus is likely to be restricted to industrial research environments, other automated oocyte perfusion systems have been described that would be suitable for smaller scale laboratories (e.g., Joshi et al., 2004). 

Centrifuges can be very efficient when separating cells from culture media. Consequently, they can be used either in harvesting of mammalian cells [1,21-23] or, despite their mechanical complexity, as cell retention device in long-term perfusion systems (Table 3). 

The degree of cell separation is an important parameter to be evaluated in perfusion systems. This can be done through the use of some concepts as cell separation efficiency, grade efficiency, and cut size. These concepts are applicable to any equipment whose performance remains constant if the operational conditions do not change. They are valid, therefore, for equipment such as sedimenting centrifuges, hydrocyclones, gravitational settlers, etc. 

The terminal settling velocity v, can be obtained by Eq. (1) and, in a perfusion system, the overflow rate Q is equal to the product between the specific perfusion rate D and the bioreactor volume V. Hence ... 

In practice, an area three times larger than is recommended. As Eq. (8) shows, when scaling up perfusion systems, the settling area is directly proportional to the reactor volume, for a constant specific perfusion rate. 

For the application of a continuous perfusion system, it is necessary to know what elution rate to use under steady state conditions in order to minimize either the total volume of solution to be injected or the duration of the injection. The practical objective of a scintigraphic-examination is to accumulate, in a given organ, a sufficient radioactivity to produce good counting statistics. An analytical study of this problem brings us to the formulation of the following equation ... 

Table 19.1 Moments and disposition parameters of 32P-pDNA and 32P-oligonucleotides in the single-pass rat liver perfusion system...

Figure 19.5 Physiological pharmacokinetic model for hepatic uptake of drug constantly infused in the isolated rat liver perfusion system. Q, flow rate (mL/min) Cb, inflow concentration (pg/mL) Cs, sinusoidal concentration (pg/mL) Vs, sinusoidal volume (mL) X, binding constant (pg) Xm, maximum binding amount (pg) K, binding constant (mL/pg) kmt, internalization rate constant (min-1).

Figure 19.6 Schematic presentation of perfusion system of the tissue-isolated tumor preparation.

Kakutani, T., Yamaoka, K., Hashida, M. and Sezaki, H. (1985) A new method for assessment of drug disposition in muscle application of statistical moment theory to local perfusion systems. J. Pharmacokin. Biopharm., 13, 609-631. 

Nakajima, S., Koshino, Y., Nomura, T., Yamashita, F., Agrawal, S., Takakura, Y. and Hashida, M. (2000) Intratumoral pharmacokinetics of oligonucleotides in a tissue-isolated tumor perfusion system. Antisense Nucleic Acid Drug Develop., 10, 105-110. 

Yoshida, M., Mahato, R.I., Kawabata, K., Takakura, Y. and Hashida, M. (1996) Disposition characteristics of plasmid DNA in the single-pass rat liver perfusion system. Pharm. Res., 13, 599-603. 

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