Development of poly(ethylene glycol)-coated vesicles as cardiovascular imaging agents for nuclear medicine

The development and use of poly(ethylene glycol) (PEG)-coated vesicles as nuclear medicine blood pool imaging agents is described from the initial synthesis of chelator, through labeling of vesicles with technetium-99m ([sup 99m]Tc), to the final testing in a human subject. Using hexamethyl-propyleneamine oxime (HM-PAO) as the chelate molecule, a novel pH gradient method was developed for the rapid, robust and reproducible labeling of pre-formed vesicles with labeling efficiencies greater than 90%. In vivo (pyrogen and hemodynamic studies in rabbits) and in vitro (CH50 hemolytic assay) studies were conducted to determine the safety and tolerability of PEG-coated vesicles. Results showed that there was no significant alterations in hemodynamic parameters or activation of the complement system. Also, vesicles and the vesicle preparation procedure were found to be non-pyrogenic. In vivo studies in rabbits revealed that vesicles with 4.5 mol% PEG, exhibited both lipid dose-dependent and -independent circulation half-lives contrary to published data. A circulation half-life of ~ 15 hours was achieved at lipid dose greater than ~1.0 μmol of total lipid/kg of body weight. Based on these in vitro studies and in vivo rabbit results, a vesicle based kit was developed and tested in a human subject. The left ventricular ejection fraction (LVEF) was calculated using labeled vesicles and was compared to the LVEF calculated with the current standard of radiolabeled autologous red blood cells (RBCs). The values were found to be similar (69% for RBCs and 73% for vesicles) indicating that PEG-coated vesicles labeled with [sup 99m]Tc are a suitable alternative to RBCs for cardiovascular imaging.Medicine, Faculty ofBiochemistry and Molecular Biology, Department ofGraduat

Temperature induced condition of univalence in wheat

A number of diploid and polyploid species of wheat have been subjected to the condition of high temperature. The various temperature treatments have been found to induced formation of univalents in a number of Pollen mother cells of different varieties. The distribution of cells showing such univalents has been studied. It has been found that in almost all the plants, the distribution is of a poisson type. The significance of this type of distribution has been discussed

Ribonucleic acid and high temperature sensitivity in wheat

A comparative estimate of ribonucleic acid in the root-tip cells of different species has been made by the autoradiographic technique. It was found that no correlation exists between the turn-over of RNA and temperature sensitivity of chromosomes in the different wheat species. It has, however, been found that the addition of the B genome in the polyploid species has made a greater contribution to the capacity of the cells to synthesize RNA compared to the addition of the D genome