Modification of liposomes by addition of HCO60. I. Targeting of liposomes to liver by addition of HCO60 to liposomes.

The influence of HCO60 on the blood clearance and tissue distribution of soybean phosphatidylcholine (PC) liposomes, encapsulating alpha-tocopherol as a marker, was studied in rats. The liposomes were prepared by the hydration method from a lipid film containing different amounts of HCO60, and by extrusion through a 0.1 micron polycarbonate membrane filter. The blood clearance and liver uptake of alpha-tocopherol after i.v. administration increased with increasing the amount of HCO60 the liposome contained. With 80 wt% HCO60 liposomes, the accumulation of alpha-tocopherol in the liver was approximately three-fold that of the 100% PC liposomes. The uptake by lungs, spleen and kidneys did not change with the addition of HCO60. The findings obtained in a gel-filtration study suggested that alpha-tocopherol is not removed from the liposomes, with or without HCO60, by rat plasma proteins and the HCO60 micelle may form a complex with rat plasma proteins. Our findings suggest that liposomes containing large amounts of HCO60 (more than 60 wt%) will be useful for delivering drug to the liver.

Modification of liposomes by addition of HCO60. II. Encapsulation of doxorubicin into liposomes containing HCO60.

The efficiency of encapsulation of doxorubicin (DOX) into liposomes containing HCO60 was studied. Empty egg phosphatidylcholine (PC) liposomes containing various amounts of HCO60 were passed through a polycarbonate membrane filter (0.1 micron). Closed vesicles were formed even with liposomes containing 90 wt% HCO60. DOX was encapsulated efficiently (more than 1 mg DOX/8 mg lipids) using a pH-gradient method. HCO60 accelerated the leakage of DOX from liposomes into phosphate buffer at temperatures above 25 degrees C. HCO60 suppressed the leakage of DOX from egg PC/cholesterol (7/3, w/w) liposomes into phosphate buffer containing 50% fetal bovine serum (FBS). Studies on the interaction between liposomes and serum components using zeta potential and turbidity suggest that HCO60 prevents the liposomes from interacting with serum components.

Complete disappearance of metastatic abdominal tumors from gastric cancer after treatment with irsogladine maleate.

A 60-year-old woman with gastric cancer had undergone partial gastrectomy in September 1989. Pathological examination revealed a poorly differentiated adenocarcinoma of pT3pN3pM0 (not resected for cure), stage IV. Postoperative adjuvant therapy comprised 1-(tetrahydro-2-furanyl)-5-fluorouracil plus uracil and OK-432. On 11 August 1990, two forefinger-tip-sized tumors were palpated beneath the operation scar. They increase in size, the superior tumor reaching 4x3 cm, the inferior tumor 5x3 cm on 5 September. Then, on 17 September, the inferior tumor was resected but the superior tumor remained; the histological type was poorly differentiated adenocarcinoma. After the operation, from 20 September, she was given 4 mg irsogladine maleate orally every day. On 8 October, there was no increase in the size of the superior tumor. By 29 October, the superior tumor had disappeared and no further tumor appeared thereafter; the patient showed no sign of relapse.

A new screening method for evaluating antitussives in conscious guinea pigs.

In order to evaluate the effects of antitussive agents, a new method for inducing the cough reflex in guinea pigs was devised. Male guinea pigs weighing 300-450 g were fixed in a supine position under non-anesthesia. A puncture electrode made by a stainless steel wire (0.2 mm diameter, 10 cm length) was inserted into the trachea through a guiding cannula (needle size 23G, Terumo). The optimal parameters of electrical stimulation given on the tracheal mucous membrane were a square-wave pulse with a 40 Hz frequency, duration of application 5 s. Fifty percent of antitussive doses (AtD50) of the drugs used in this study were as follows: codeine, 3.35 mg/kg (i.p.), 7.5 mg/kg (p.o.); morphine, 1.2 mg/kg (i.p.), 2.5 mg/kg (p.o.); picoperidamine, 10.9 mg/kg (i.p.), 22.6 mg/kg (p.o.); benproperine, 14.5 mg/kg (i.p.), 22.6 mg/kg (p.o.); fominoben, 13.9 mg/kg (i.p.), 477 mg/kg (p.o.). These AtD50s are much less as compared with those obtained using other methods. These results suggest that the present method for inducing the cough reflex in guinea pigs is useful for the first screening of antitussives, especially when only a small quantity of the materials is available.

[Conditioning of emotional behavior caused by hypothalamic stimulation (4). Effects of drugs on conditioned avoidance and escape behavior].

In the present study, effects of psychotropic drugs were analyzed by observing avoidance and escape behavior or rabbits under hypothalamic electrical stimulation. In avoidance behavior, chlorpromazine (CPZ) and diazepam (DZP) depressed avoidance response and extended avoidance response latency and head movement latency. Autonomic behavior such as opening of palpebral fissure and pupil size were also delayed. The locus of movement and count of head movement were depressed by the administration of each drug. On the other hand, unlike CPZ, DZP extended escape response latency. On escape behavior, effects of CPZ and DZP were apparently different. Unlike CPZ, DZP induced avoidance behavior and increased locus of movement. With methamphetamine, no avoidance behavior was observed, but under conditional stimulation, the behavior and the escape response latency were decreased. Chlordiazepoxide induced avoidance behavior.

[Conditioning of emotional behavior caused by hypothalamic stimulation (3): The learned behavior caused by hypothalamic stimulation in rabbits].

In the present study, the learned behavior caused by hypothalamic electrical stimulation was examined in order to determine the effects of psychotropic drugs. Subjects were albino male rabbits with electrodes chronically implanted in the hypothalamic area. A shuttle box, which was adjusted for behavioral pharmacological estimation of drugs in rabbits, was used. A buzzer sound (85dB) and electrical stimulation of hypothalamus (100 HZ, 1 msec, 1.2-2.0V) were used as the conditional stimulation (CS) and unconditional stimulation (UCS), respectively. The same animal was trained in habituation to a buzzer sound as the CS. For avoidance conditioning in a two-compartment situation, the animal was placed in a shuttle box divided by a hurdle situated at the middle of two-compartments. After the CS was presented for 10 sec, the UCS was given. The animals were subjected to 15 conditioning trials per day. The avoidance and escape behavior model became as distinct by hypothalamic stimulation as by UCS. After termination of the experiments, extinction trials were carried out after which the animals were sacrificed, and localization of the stimulating electrodes was determined histologically.