T1-Enhanced MRI-visible nanoclusters for imaging-guided drug delivery

Iron oxide nanoparticles with extremely low dimensions have recently been explored as positive (T₁) contrast agent for magnetic resonance imaging (MRI). However, their small sizes lead to fast renal clearance and limit their use in elongated in vivo tracking or therapy monitoring. In this paper, we present a state of art approach to forming nanoclusters by crosslinking ultrasmall iron oxide nanoparticles with bovine serum albumin. This novel design not only maintains the T₁ performance of the ultrasmall nanoparticles, but also significantly increases their blood circulation times from 15 minutes to over two hours. Our breast tumor model study also exhibited enhanced contrast at tumor sites for more than 24 hours. The ability of maintaining the T₁ performance of the ultrasmall nanoparticles is significant, because previous studies have shown complete T₁ loss or signal decrease upon polymer encapsulation. This design also shows great potential in encapsulating model drug molecules, which will greatly benefit the field of imaging-guided drug delivery.

Shape-dependent cellular behaviors and relaxivity of iron oxide-based T1 MRI contrast agents

Recent research efforts about iron oxide nanoparticles has focused on the development of iron oxide-based T₁ contrast agents for magnetic resonance imaging (MRI), such as ultrasmall iron oxide nanospheres (USNPs <4 nm) and ultrathin nanowires (NW, diameter <4 nm). In this paper, we report the cellular uptake behaviors of these two types of ultrasmall scale nanostructures on HepG2 cells. Both these two nanostructures were functionalized with tannic acid and their physical and chemical properties were carefully analyzed before cellular tests. Both USNPs and NWs exhibited strong paramagnetic signals, a property suitable for T₁ MRI contrast agents. The distinct shapes also caused much difference in their cellular uptake behaviors. Specifically, the uptake of USNPs was five times higher than that of NWs after 72 hours incubation. The shape-dependent cellular uptake can potentially lead to different blood circulation times, and subsequently different applications of these two types of ultrasmall nanostructures.

Diabetic foot ulcers and amputations: estimates of health utility for use in cost-effectiveness analyses of new treatments

OBJECTIVES

Diabetic foot ulcers (DFU), infections and amputations are associated with high costs of care and loss of health. To evaluate new treatments, both the extra costs incurred and the health utility gained need to be examined. However, evaluations of treatments in diabetes are hampered by the lack of utility values for health states such as DFU. We estimated utility values for health states seen amongst DFU patients.

METHODS

We identified 13 unique health states based on presence/type of DFU and amputation. Members of the general public (n=107) received a description of each health state. They were then asked to indicate how undesirable each health state was (using the time trade-off method). Each answer was then transformed to create a value representing the "utility" of the health state, the utility value represented on a 0-1 scale.

RESULTS

Valid responses could be obtained from 96 persons. Mean values included: 0.84 (diabetes with no DFU or amputation), 0.75 (uninfected DFU, no amputation), 0.68 (no DFU, previous foot amputation), and 0.63 (uninfected DFU, previous amputation of other foot). The impact of an ulcer depended on amputation status.

CONCLUSIONS

Our values correspond with previously published results but are more detailed. In addition, since our values were derived from the general public, economic evaluations that incorporate them will use the generally preferred societal perspective. Therefore, these values are appropriate, practical and sensitive weights to calculate QALYs for cost-effectiveness analyses of foot ulcer treatments.