Evaluation of creatine transport using Caco-2 monolayers as an in vitro model for intestinal absorption.

Creatine is a nutraceutical that has gained popularity in both well-trained and casual athletes for its performance-enhancing or ergogenic properties. The major disadvantages of creatine monohydrate formulations are poor solubility and oral bioavailability. In the present study, creatine transport was examined using Caco-2 monolayers as an in vitro model for intestinal absorption. Confluent monolayers of Caco-2 cells (passage 25-35) were used for the permeability studies. Monolayers were placed in side-by-side diffusion chambers. (14)C-Creatine (0.1-0.5 microCi/mL) was added to either the apical or basolateral side, and the transport of the creatine across the Caco-2 monolayer was measured over a 90-min period. The apical to basolateral transport of (14)C-creatine was small, ranging from 0.2-3% of the original amount appearing on the receiver side in a 90-min period. Interestingly, the basolateral to apical permeability of radiolabeled creatine was substantially greater than that observed in the apical to basolateral direction. Studies with drug efflux transport inhibitors indicate that neither the P-glycoprotein nor multidrug resistance-associated protein is involved in the enhanced basolateral to apical transport of creatine.

Demand forecasting for magnetic resonance imaging services.

Healthcare providers interested in acquiring MRI technology are finding it difficult to assess demand and, therefore, financial feasibility. This article presents a quantitative technique for MRI demand forecasting that interrelates the known applications of MRI to the specific clinical setting in which it is to be employed. The first step in this technique is to identify the number of patients with diagnoses for which MRI is known to be applicable. Next, each of these diagnoses is weighted according to the percent of patients who are expected to receive MRI scans versus other diagnostic modalities. Finally, the number of patients in each diagnosis is multiplied by the weighting to estimate the number of patients for whom MRI scans can be expected. This technique was used by a consortium of three major community hospitals in Omaha, Nebraska, as the basis of their demand forecasting and was used in successfully obtaining a Certificate of Need.