No abstract

A metal‐free approach to the living ring‐opening polymerization (ROP, shown schematically) of lactide has been developed using strongly basic amines such as 4‐(dimethylamino)pyridine as transesterification catalysts. These organic catalysts must be used in combination with a nucleophile such as an alcohol, which is the actual initiating species.

We report on multidistance time-resolved diffuse reflectance spectroscopy of the head of a healthy adult after intravenous administration of a bolus of indocyanine green. Intracerebral and extracerebral changes in absorption are deduced from moments (integral, mean time of flight, and variance) of the distributions of times of flight of photons (DTOFs), recorded simultaneously at four different source-detector separations. We calculate the sensitivity factors converting depth-dependent changes in absorption into changes of moments of DTOFs by Monte Carlo simulations by using a layered model of the head. We validate our method by analyzing moments of DTOFs simulated for the assumed changes in absorption in different layers of the head model.

The present investigation was undertaken to study the kinetics of 99mTc-labelled diethylenetriaminepenta-acetate (DTPA) as compared with inulin and 51Cr-labelled ethylenediaminetetra-acetate (EDTA). Twenty patients with various degrees of decreased renal function were studied. The renal clearance, plasma clearance and volume of distribution of all three tracers were measured after a simultaneous single injection. The average renal clearance ratio 99mTc-DTPA to inulin was 0.97; the average renal clearance ratio 99mTc-DTPA to 51Cr-EDTA was 1.02. In all patients the plasma clearance of inulin exceeded that of 99mTc-DTPA. No difference was seen between the plasma clearance of 99mTc-DTPA and 51Cr-EDTA. The plasma clearance of all three tracers overestimated the simultaneously measured renal clearance; on average this was, for 99mTc-DTPA 5.7 ml/min, for 51Cr-EDTA 6.0 ml/min and for inulin 8.1 ml/min. The plasma clearance of 99mTc-DTPA correlated well with the renal clearance of inulin, but overestimated this by 3.5 ml/min on average. The volume of distribution of inulin was less than that of 99mTc-DTPA and 51Cr-EDTA. No difference was seen between the volume of distribution of 99mTc-DTPA and 51Cr-EDTA. It is concluded that the difference in the kinetics of 99mTc-DTPA and 51Cr-EDTA in patients with decreased renal function was small and without clinical relevance.(ABSTRACT TRUNCATED AT 250 WORDS)