Taka Osanai

Suppression of experimental allergic encephalomyelitis (EAE) with liposome-encapsulated protease inhibitor: therapy through the blood-brain barrier.

Experimental allergic encephalomyelitis (EAE) is an experimentally induced autoallergic demyelinating disease which is caused by immunization with a particular neuroantigen, such as myelin basic protein (MBP). Results have suggested that protease inhibitors might be useful therapeutically. Leupeptin (acetyl-l-leucyl-l-leucyl-argininal), a protease inhibitor of tripeptide nature, was effective in suppressing EAE in guinea pigs, when administered in a form of liposomes consisting of egg lecithin, cholesterol and sulfatide. The drug seemed to be transported into the central nervous system (CNS) tissues across the blood-brain barrier with the aid of a particular type of liposomes as vehicle. Some outbred Hartley guinea pigs completely recovered from distinct symptoms of EAE, such as loss of weight, paralysis, incontinence and/or diarrhea, when treated i.p. every day with lecithin-cholesterol-sulfatide (molar ratio, 4∶5∶1) reverse-phase evaporation vesicles-encapsulated leupeptin (REV-Leu) from day 6 after sesitization with 30 μg of bovine MBP. Scarcely any typical histopathological changes of EAE were found in the CNS of most survivors treated with REV-Leu.

Hypophagia induced by endogenous or liposome-encapsulated 3,4-dihydroxybutanoic acid

Hypophagia induced by 3,4-dihydroxybutanoic acid (2-deoxytetronic acid, 2-DTA), an endogenous short-chain polyhydroxymonocarboxylic acid, was investigated in rats. Intraperitoneal injection of 2500 mumol 2-DTA did not suppress feeding, but 2.5 mumol 2-DTA injected into the third cerebroventricle did. To efficiently transport exogenous 2-DTA into the brain, its encapsulation and delivery in specially made sulfatide liposomes was attempted. Feeding was suppressed dose-dependently by intraperitoneally injected 2-DTA in liposomes. Injection of 2500 mumol 2-DTA into the common carotid artery also suppressed feeding. Administration by either route prolonged postprandial intermeal interval with no change in meal size, as was observed after central administration of 2-DTA. Injection of 2.5 mumol 2-DTA into the third cerebroventricle elevated plasma glucose level, leaving insulin and free fatty acids unaffected. These findings, together with previous results, indicate that at least one site for the physiological action of 2-DTA is in the hypothalamic centers for food intake.

Gangliosides stimulate dome formation in cultured canine kidney epithelial cell line (MDCK).

The effect of exogenous gangliosides on the occurrence of domes in MDCK cell cultures was investigated in view of the involvement of both dome formation and gangliosides in cell growth, differentiation and transepithelial transport. Dome formation was increased by gangliosides in medium free of fetal calf serum. Among the gangliosides tested, GM3 and GD3 isolated from porcine kidney were most active, increasing the dome number 12–17‐fold. Since gangliosides from kidney were more active than those from brain and erythrocytes, the hydrophobic moiety as well as sialic acid might be involved in this activity. These results indicate that tissue‐specific molecules of gangliosides function as inducers or mediators of dome formation. The mechanism probably involves adenylate‐ cyclase or another transmembrane biosignal‐transducing system.

Role of intramuscular enzymatic changes in the development of muscular weakness in rats with experimental allergic neuritis

We investigated the role of intramuscular enzymatic changes in the development of muscular weakness in rats suffering from experimental allergic neuritis. At an initial stage without apparent clinical symptoms, enzymatic changes of similar types occurred in the muscles of the forelimbs and hind limbs. At a later stage when the weakness appeared in the hind limb but not in the forelimb, dissociation of the pattern of the enzymatic changes occurred between the two limbs. Comparison of the intramuscular enzymatic changes between the two stages and between the two limbs suggested that the increased activities of aminopeptidases and endopeptidases play some important roles in the development of muscular weakness in this experimental model. Low molecular weight protease inhibitors may thus be worthy of a trial in this disease condition.