Malaria still remains a serious health problem in large areas of the world, and in this article, recent research progress mainly made by us toward malaria vaccine development has been reviewed. 1) Peptide vaccines (antigens) of immunodominant tetrapeptide repeats (NANP and NVDP) of the circumsporozoite surface protein of the malaria parasite, Plasmodium falciparum, were genetically produced in E. coli as a fusion protein with a part of human growth hormone, which has affected on the conformations and immunogenicities of the peptide vaccines. 2) Monoclonal antibodies against the peptide antigens were produced by fusion of mouse spleen cells with myeloma cells, and the Fab's obtained by partial digestion of the antibodies with papain were used for the measurement of the dissociation constants of the antigen-antibody complexes. The amino acid sequence of the Hv region in Fab domain was also deduced from its nucleotide sequence.
The importance to elucidate the mechanisms of drug distribution in tissues has been discussed in this review. By considering several factors such as tissue binding, plasma binding, membrane permeability and tissue interstitial fluid space, the tissue distribution states of drug have been characterized based on the biochemical and pharmacokinetic studies. These physiological pharmacokinetic analyses have been applied to evaluate the determinant factors of inter-organ, drug to drug, interspecies or age related changes of tissue distribution of drug. The mechanisms of membrane permeability of drug which could play the most important role to regulate the drug distribution have been discussed. The drug distribution to the brain is strictly restricted by the function of the blood-brain barrier (BBB). The drug transport mechanisms at the BBB have been discussed. Especially, the role of carrier-mediated and absorptive-mediated transport systems at the BBB has been focused on.
Emulsion stability is often expressed in terms of the turbidity ratio, the ratio of the turbidities, τ, of a diluted emulsion estimated at two wavelengths λ1 and λ2. In this paper, it is shown that the theoretical values of the turbidity ratio, f, can be calculated by f=τ(λ1)/τ(λ2)=(λ1/λ2)-n, since the values of the wavelength exponent n for spherical particles are known to be a function of m and D, where m is the relative refractive index of the particle to the medium and D is the diameter of the particle. The relation between the experimentally determined turbidity ratio, f, at λ1=800 and λ2=555, and the average particle diameter determined by optical microscopy agreed well with the theoretical curves with m=1.10 for vegetable oil and m=1.20 for polystyrene latex. Therefore, the oil-in-water emulsions stabilized with gum arabic were studied by use of the turbidity ratio method. For the emulsions of vegetable oils, the turbidity ratio decreased and the particle diameter decreased with the concentration of gum arabic. Addition of β-carotene in the oil phase, up to the ordinary dose, resulted in a very little change in the diameter. The effect of the kind of vegetable oil on the particle diameter was not large, but the emulsion of rice oil had a little smaller diameter than that of olive oil or soybean oil. The results obtained with triglycerides as an oil phase were dependent on their molecular weight rather than their iodine value.
In order to elucidate the relationships between the antitumor activity and the molecular structure of novel acridine derivatives (la-f, and 2a-e in Chart 1) the DNA-binding properties (intercalation) of the derivatives were examined by the quenching in fluorescence of an ethidium-DNA complex, which may be caused by the displacement of DNA-bound ethidium by a second DNA-binding ligand, acridines. The concentration (C50 value) of the acridine necessary to reduce the initial fluorescence of DNA-bound ethidium by 50% showed a good correlation with their antitumor activities. The fluorescence quenching of the acridines was examined using 4'-(9-acridinylamino)-methanesulfonanilide (amsacrine, AMSA) as a typical standard of the second DNA-bound ligand, and calf thymus DNA with an apparent site size of two base pairs.
The biological activity of a preparation of heat killed cells of Enterococcus faecalis, FK-23 which was isolated from the feces of a healthy human, was investigated in C3H/He mice. Intraperitoneal injection of the preparation caused an accumulation of neutrophils and macrophages in the peritoneal cavity of the mice 6 h later. As a parameter of the activation of macrophages, the effect of the FK-23 preparation on the production of tumor necrosis factor (TNF) was examined. The mice were given two consecutive intravenous injections of the preparation at a dose of 10μg/mouse and, 3 h later, of 300μg/mouse. The TNF level in the sera reached 99 U/ml in mice 2 h after the second injection. This preparation also stimulated peritoneal macrophages to produce TNF in vitro and increased the capacity of neutrophils to adhere to plastic plates and to release active oxygens, but did not induce blastogenic transformation of lymphocytes. These results suggest that the FK-23 preparation is a biological response modifier (BRM) with various activities on phagocytes similar to a streptococcal antitumor agent, OK432.
The effects of ascorbic acid (AA) on the metabolic fate of iproniazid (IPN) and on the free radical intermediates derived from IPN were investigated in rats. After oral administration of IPN with or without AA, the plasma concentration and the urinary excretion of IPN and its metabolites were determined by gas chromatography-mass spectrometry using stable isotope labeled compounds as internal standards. In the excretion of IPN and its metabolites except hydrazine (Hy), the differences between co-administration and single administration were not observed. The excretion of Hy, which is a known hepatotoxic metabolite, decreased clearly in the co-administration of IPN and AA. When IPN and AA were co-administered orally, the profiles of plasma levels of IPN and its metabolites were almost similar after the administration of IPN alone. Furthermore, no differences between i.v. co-administration and i.v. administration alone were observed. These results indicated that AA did not affect both absorption and metabolism of IPN. By the electron spin resonance (ESR) spectroscopy and spin-trapping technique, the ESR signals due to the α-(4-pyridyl l-oxide)-N-tert-butylnitrone (4-POBN) adducts induced by isopropylhydrazine (IP-Hy) were two-fold higher than those by IPN in microsomal systems. The free radical formations of IPN and IP-Hy were significantly inhibited by AA in a dose dependent manner. The 4-POBN-trapped radical species generated from IPN and IP-Hy were presumed to be an isopropyl radical by the results of mass spectrometry. By the addition of an inhibitor of cytochrome P-450 such as SKF 525-A, the generation of the radicals derived from IPN and IP-Hy decreased, indicating that the radicals are formed by cytochrome P-450-dependent microsomal systems. In vivo experiments, the radical generations after i.p. administration of IPN with AA were significantly depressed in the plasma and liver, compared with those after the administration of IPN alone. On the basis of these results, it was suggested that AA may reduce the IPN-induced hepatitis.
Using the Ames/Salmonella/microsome assay, we examined the antimutagenic effect of the hexane extract of Armeniacae semen (apricot (Prunus armeniaca L.) seed), Persicae semen (peach (P. persica BAT.) seed), and seeds of cherry (P. avium L.), plum (P. salicina LINDLE) and almond (P. dulcis MILL). Hexane extracts of Armeniacae semen and Persicae semen inhibited the mutagenicity of benzo[a]pyrene (B[a]P), but those of seeds of cherry, plum and almond did not. The mutagenicities of 3-amino-1, 4-dimethyl-5H-pyrido[4, 3-b]indole (Trp-P-1) and 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2) were also inhibited by the extracts of Armeniacae semen and Persicae semen. Inhibitory substances in Persicae semen were fractionated by silica gel column chromatography and high performance liquid chromatography, and were identified as oleic acid and linoleic acid. The contents of oleic acid and linoleic acid were 0.7 and 0.4% in the hexane extract of Armeniacae semen, and 1.5 and 0.5% in that of Persicae semen, respectively.
Factor C, an endotoxin-sensitive serine-protease zymogen, was prepared by cation-exchange chromatography using SP Toyopearl 650C. This preparation exhibited a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The endotoxine-dependent Factor C activity was determined from the amount of released ammonium ions by cleavage of N-tert-butoxy-carbonl Val-Pro-Arg-NH2 using an ammonia electrode. The sensitivity towards the endotoxin was approximately 5×10-8 g/ml.
Tropane alkaloids, contained in gastrointestinal drugs including Scopolia Extract, were determined using high-performance liquid chromatographic method. Tropane alkaloids in commercial drugs were extracted with 0.5 N hydrochloric acid test solution. This solution was adjusted to pH 10.0 with a strong ammonia solution, extracted with ethyl ether, and separated on TSKgel ODS-120T (4.6mm i.d.×15cm ; temperature, 30°C ; flow rate, 1.5 ml/min ; detector, UV 210 nm) with a mixture of 1/15 M sodium phosphate buffer (pH 2.5) and acetonitril (68 : 32) containing 12 mM sodium dodecyl sulfate. The contents of atropine in the gastrointestinal drugs were 0.25-0.34 mg (coefficient of variation=0.20-2.61%) a day.