Effect of lyophilization on the characteristics and stability of melanin loaded liposomes

The present study was directed to optimize the stability of melanin liposomes utilizing the technique of lyophilization. Two types of cryoprotectants; sucrose and lactose, each in two concentrations of 5% and 10% were used. Lyophilized liposomes [10% lactose] either fresh or stored for one year at 5°C showed no significant changes [P>0.05] in the phase transition temperatures [Tc], structure and shape, and size distribution of the fresh unlyophilized liposomes. The fresh unlyophilized liposomes were unilamellar with Tc of 41.6°C and an average size of 5.21 micro m. The stored unlyophilized liposomes showed a significant [P<0.05] decrease in Tc [32.8°C] and increase in the average size [15.6 micro m] with the formation of onion- like multilamellar vesicles compared with the fresh unlyophilized ones. Lyophilization of melanin liposomes with different cryoprotectants significantly [P<0.001] decreased the rate of leakage of entrapped melanin from the liposomal structure compared with the unlyophilized ones. This cryoprotection effect was significantly [P<0.05] increased by the use of lactose and by increasing the cryoprotectant concentration. The entrapped melanin in lyophilized liposomes with 10% lactose was chemically stable for six months at 5°C as evaluated by mass spectroscopic analysis. As a conclusion, lyophilization with 10% lactose maintained the chemical stability of melanin and significantly improved the physical stability of melanin liposomes

Correlation between the degree of periportal thickening, portal blood flow and splenic volume

Schistosomiasis leads to presinusoidal hepatic fibrosis which determines the prognosis of the disease and has variable sequences on the portal haemodynamics. In order to evaluate the relation between the degree of hepatic fibrosis, portal hypertension and splenic volume by means of ultrasound and Duplex Doppler, 35 schistosomal patients [25 males and 10 females with a mean age of 37 years] showing various degrees of periportal fibrosis were studied. The grade of periportal fibrosis, portal blood flow, portal vein diameter and splenic volume were determined by means of ultrasound and Duplex Doppler. The portal vein diameter showed a mean of 10.8 mm, portal blood flow showed a mean of 877 cm 3 and the splenic volume had a mean of 149 cc. There was a positive significant linear correlation between the portal vein diameter and the grade of fibrosis the portal blood flow and the grade of fibrosis and the splenic volume and the grade of fibrosis. In conclusion, hepatic periportal fibrosis affects the portal haemodynamics. It correlates positively with the portal blood flow and the splenic volume. Furthermore ultrasound and Duplex Doppler are simple, non invasive techniques for evaluation of haemodynamic changes in schistosomal periportal fibrosis

Solvatochromic behaviour of the electronic spectrasome -phenylene derivatives

The electronic absorption spectra of a series of o-phenylene compounds have been measured in a series of different solvents. The effects of solvent on the spectra have been discussed and the solvent induced spectral shifts have been analyzed in relation to the different solute-solvent interaction mechanisms