Binding rate constant of Tc-99m DTPA galactosyl human serum albumin measured by quantitative dynamic SPECT--clinical evaluation as a total and regional liver function test.

To evaluate the clinical utility of a new method with dynamic single photon emission computed tomography (SPECT) and scatter and attenuation compensation to estimate both total and regional liver function quantitatively. Five controls, 20 patients with chronic liver disease, and 2 patients with Budd-Chiari syndrome were studied. Dynamic liver SPECT data were acquired during 20 minutes after injection of Technetium (Tc)-99m diethylenetriaminepentaacetic acid (DTPA) galactosyl human serum albumin (GSA) with scatter and attenuation compensation. The binding rate constant of Tc-99m GSA (Ku) was derived quantitatively from the Patlak plot based on kinetic models for GSA receptor binding. The mean Ku was obtained by dividing the Ku value (total Ku) by the liver volume. Both total and mean Ku were significantly lower in patients with chronic liver disease than in controls (302 +/- 112 vs. 523 +/- 78 ml/min; p < 0.001, 0.26 +/- 0.11 vs. 0.43 +/- 0.03 ml/min/cm3; p < 0.001). In the patient group, both total and mean Ku were significantly correlated with the results of conventional liver function tests and the histological severity of chronic liver disease. In 2 patients with Budd-Chiari syndrome, the mean Ku was lower in the right lobe, where the hepatic veins were occluded, than in the left lobe, where draining veins were patent. In conclusion, this method is a reliable diagnostic technique for estimating total and regional liver function.

A regulatory subunit of smooth muscle myosin bound phosphatase.

The relationship between two putative myosin-binding subunits of smooth muscle myosin phosphatase was investigated. A monoclonal antibody (MoAb) to the 58 kD component of smooth muscle myosin-bound phosphatase (MBP) cross-reacted with a 130 kD protein in extracts of fresh chicken gizzards. The MoAb in combination with protein A immunoprecipitated from gizzard extracts a complex of the 130 kD protein plus the 38 kD catalytic subunit of the type 1 delta protein phosphatase. It is proposed that the 130 kD component is a native subunit of MBP and that the 58 kD protein is its proteolytic degradation product. The distribution of the 130 kD component in chicken tissues was screened using the MoAb. An immunoreactive band of appropriate mass was detected in all tissues except liver and skeletal muscle. Higher concentrations of the 130 kD component were evident in the smooth muscle samples.