In vivo measurement of hepatic iodine concentration using fluorescent excitation analysis

A device for a noninvasive evaluation of coronary bypass grafts

A new device is presented for evaluating the patency of coronary bypass grafts. Bypass grafts are located within the chest cavity using a Compton backscatter imaging (CBI) technique that creates frontal plane tomographic images. The tomographic image pixels are mapped into computer memory and displayed. A display pointer is used to mark the position of the bypass graft. The computer uses that information to subsequently position a radiation detector, such that it "looks" at the location of the bypass graft within the closed chest. The patency of the graft is then evaluated by monitoring an X-ray induced iodine fluorescence transient in the graft, subsequent to a peripheral intravenous contrast injection. This imaging and graft evaluation device is relatively inexpensive and its application does not require cutdowns or catheterization. The associated radiation dose is 1/10 to 1/50 of that associated with alternative X-ray graft patency evaluation techniques. Preliminary testing has been performed on mechanical and animal models.

Measurement of the stratum corneum drug reservoir to predict the therapeutic efficacy of topical iododeoxyuridine for herpes simplex virus infection

A rapid, in vivo measurement of the penetration of antiviral compounds into the skin would improve our ability to predict the therapeutic efficacy of topical treatments for herpes simplex virus (HSV) infection. We have studied the concentration of iododeoxyuridine (IDU) in the stratum corneum of guinea pig skin by tape stripping at different time points after single and multiple topical doses of the drug. These results were correlated with the efficacy of topical IDU against an experimental cutaneous HSV infection. Ten adhesive tape strippings were performed on depilated guinea pig dorsum in vivo at serial intervals after a single topical dose of [3H]IDU. Iododeoxyuridine levels in the stratum corneum peaked at 1-3 h (67-70 mg/g of tissue) and then gradually declined over the next 3-24 h. We hypothesized that the peak IDU stratum corneum concentration would correlate with therapeutic efficacy. Accordingly, we determined the quantity of IDU in guinea pig stratum corneum 2 h after a topical application of seven different concentrations of IDU in dimethylsulfoxide (DMSO) and examined the in vivo efficacy of these formulations in an experimental dorsal cutaneous HSV-1 infection in guinea pigs. The results showed an excellent correlation between the quantity of IDU in the stratum corneum and reduction in lesion severity (r = 0.95-0.97). Fifteen percent IDU in DMSO provided the highest therapeutic efficacy (90-94%). We also studied the relationship between the clinical efficacy of different dosing frequencies and the amount of IDU in the stratum corneum. Serial IDU stratum corneum concentrations were measured over 24 h following 1, 2, 3, or 4 applications per day of 1, 3, and 15% IDU in DMSO treatments and parallel efficacy studies of the different regimens were conducted in the animal model. Within each dosing frequency, the cumulative amount of drug in the stratum corneum correlated with the strength of the test formulation and with efficacy in the animal model. For each of the three formulations, increasing the number of daily doses from one up to three led to progressive increases in cumulative stratum corneum IDU levels and clinical efficacy. An increase in the number of daily applications to four had little effect on drug efficacy and was associated with a plateau in stratum corneum IDU levels. Stratum corneum IDU concentrations were rapid and easy to determine and correlated well with clinical events.(ABSTRACT TRUNCATED AT 400 WORDS)