Antimicrobial and antifungal agents derived from clay minerals

A silver chelate of 2-(4-thiazolyl)-benzimidazole, dodecyltrimethylammonium cation and hexadecylpyridinium cation have been intercalated between montmorillonite, and the resulting samples were subjected to examination of their thermostabilities by thermogravimetry and carbon dioxide evolution analysis up to 500 °C in air. The degradation behaviour of the intercalant was significantly changed by intercalating between the montmorillonite layers. Two quaternary ammonium cations were released from the montmorillonite both at the same temperature, which was higher than those for the quaternary ammonium cations themselves. This relation was also observed in the case of 2-(4-thiazolyl)-benzimidazole. The improvement of the thermostability after intercalation can be attributed to the bonding between the intercalant and the host montmorillonite layers.     

Is it possible to differentiate between choledochal cyst and congenital biliary atresia (type I cyst) by antenatal ultrasonography?

Both choledochal cyst and congenital biliary atresia (type I cyst) may share the same ultrasonographic pattern. We report 2 cases which were shown to have cystic structures on the upper abdomen by antenatal ultrasonography. The size of the choledochal cyst found at 24 weeks' gestation increased steadily as gestational age advanced. But the size of the cyst in congenital biliary atresia found at 29 weeks' gestation remained unchanged throughout the remaining pregnancy. Cyst enlargement, therefore, may suggest the possibility of a choledochal cyst.     

Protein modification by a Maillard reaction intermediate methylglyoxal. Immunochemical detection of fluorescent 5-methylimidazolone derivatives in vivo

Methylglyoxal (MG), an endogenous metabolite that increases in diabetes, is a common intermediate in nonenzymatic glycation (Maillard reaction) in vivo. Here we describe the immunochemical approach to the detection of MG adducts in proteins in vitro and in atherosclerotic lesions of human aorta in vivo. The reaction of protein (bovine serum albumin) with MG led to selective loss of arginine and lysine residues, accompanied by the formation of 5-methylimidazolone (N delta-(5-methylimidazolon-2-yl)ornithine) and imidazolysine (1,3-di-lysino-4-methylimidazole) derivatives, respectively. The anti-5-methylimidazolone antibody was prepared by immunizing rabbits with a MG-keyhole limpet hemocyanin conjugate and purifying the serum on an affinity gel prepared by covalent attachment of the 5-methylimidazolone derivative. The antibody cross-reacted with the proteins treated with not only MG but trioses, such as hydroxyacetone, dihydroxyacetone, and glyceraldehyde. The immunohistochemical analysis revealed that atherosclerotic lesions of human aorta contained 5-methylimidazolone derivatives whose distributions were identical to those of advanced glycation end products (AGEs) detected by the anti-AGE antibody.     

Dielectric properties above the glass transition for a series of epoxide prepolymers

Dielectric properties above the glass transition have been investigated for a series of bisphenol-A type epoxide prepolymers (388 ≤ M?_w ≤ 2640). Dielectric measurements were performed over a frequency range of 50 Hz–1 MHz using a vertical parallel plate cell which was constructed in the laboratory. The dielectric α-relaxation for each prepolymer fits the empirical model of the Havriliak–Negami equation. The temperature dependence of the dielectric relaxation time τ is described by the Williams–Landel–Ferry (WLF) equation as well as that of the direct current conductivity σ, which can be measured using the same cell. The relationship between τ and σ, σ^· τ^m = const, is derived from experimental results. The exponent m, which depends on the molecular weight of the prepolymer, is considered to correspond to the ratio of the segmental mobility to ionic mobility. The dielectric loss ε″ can be used as an indicator of the direct current conduction in the temperatures where the ionic component in ε″ becomes much larger than the dipole one.     

Carbon nanotubes prepared from three-layered copolymer microspheres of acrylonitrile and methylmethacrylate

Carbon nanotubes (CNTs) were synthesized from fine three-layered copolymer microspheres using the polymer blend technique. Diameter of PMMA core/Poly(AN-co-MMA) shell-1/PMMA shell-2 microspheres, prepared by a radical soap-free emulsion polymerization of methylmethacrylate (MMA) and acrylonitrile (AN), was between 400 nm and 500 nm. Microspheres were subjected to melt-spinning at 305 °C, stabilizing in oxygen at 220 °C for 4 h, and finally carbonizing at 1000 °C for 30 min. FE-SEM study of carbonized sample revealed the presence of CNTs arrays on carbon blocks. Similar arrays were observed in a comparative CNTs sample prepared from three-layered microspheres with the pure PAN shells-1 layers. HRTEM showed that the CNTs derived from copolymer microspheres had different structure when compared to the control sample, i.e. CNTs often adhered to each other and contained the internal compartments. The insufficient PMMA shell-2 coating of copolymer microspheres is believed to be a reason for CNTs adhesion. The possible mechanisms of the carbon block formation and the adhesion of CNTs are introduced.     

Release of salicylic acid through poly(vinyl alcohol)/poly(vinyl pyrrolidone) and poly(vinyl alcohol‐g‐N‐vinyl‐2‐pyrrolidone) membranes

A controlled release profile of salicylic acid (SA) for transdermal administration has been developed. Poly (vinyl alcohol) (PVA) and Poly(vinyl alcohol)/Poly(vinyl pyrrolidone) (PVP) blended preparations were used to prepare the membranes by solvent‐casting technique. The release of the drug from the membranes was evaluated at in vitro conditions. The effects of PVA/PVP (v/v) ratio, pH, SA concentration and temperature were investigated. 60/40 (v/v) PVA/PVP ratio was found to be the best ratio for the SA release. Increase in pH and temperature was observed to increase the transport of SA. Instead of blending PVA with PVP, N‐Vinyl‐2‐pyrrolidone (VP) was grafted onto the PVA and the delivery performance for SA was compared with that of the blended PVA/PVP membranes. Grafted membranes gave higher transport percentages than the blended membranes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1244–1253, 2006     

Antitumor activity of synthetic alkylphospholipids with or without PAF activity

1-O-Octadecyl-2-O-methyl-sn-glycero-3-phosphocholine (ET-18-OMe) has been reported to possess definite antitumor activity in vivo. Twenty-two alkyl lysophospholipid analogs were chemically synthesized, and their antitumor activity against mouse experimental tumors (Sarcoma 180, MM46, P388) was examined. Among them, 1-O-octadecyl-2-O-acetoacetyl-rac-glycerol-3-phosphocholine was found to show antitumor activity similar to ET-18-OMe with less acute toxicity. Intravenous injection of the ET-18-OMe withsn-3 configuration retarded the subcutaneous growth of Sarcoma 180 cells effectively, while the growth inhibition by thesn-1 isomer was much less effective. This stereospecificity was similar to that observed in their activities as platelet-activating factor (PAF) agonists. The acetoacetyl compound, another PAF agonist, showed similar stereospecific antitumor action in vivo. These findings suggest that some alkyl lysophospholipids may activate host cells to a cytostatic stage against tumor cells in vivo through binding to a PAF receptor. Our preliminary results indicated that the responsible cells under these conditions might be primarily immature macrophages present in the bone marrow. No appreciable or even adverse stereospecificity was observed in the different sets of experiments where the activity of ET-18-OMe against MM46 tumor cells in vivo or the direct cytotoxicity against human promyelocytic leukemia HL-60 cells in vitro was examined. Under, some conditions, the antitumor activity of ET-18-OMe in vivo may be revealed through direct cytotoxicity and/or modulation of the host defense system by “nonspecific” mechanisms. Some alkylphospholipids without PAF activity may also show antitumor activity through similar, “nonspecific” mechanisms.     

Guinea pig bone marrow cells treated with platelet-activating factor generate factor(s) which affects their DNA synthesis and microbicidal activity

We have previously reported that platelet-activating factor (PAF) induces proliferation and microbicidal activity of guinea pig bone marrow cells. In the present study, we have found that the conditioned medium of PAF- or nonmetabolizable PAF agonist-treated guinea pig bone marrow cells augmented DNA synthesis and induced microbicial activity of bone marrow cells. A PAF specific antagonist, CV-6209, inhibited generation of the active conditioned medium by PAF. Addition of the PAF antagonist only partially suppressed the augmentative effect of the active conditioned medium on DNA synthesis; this is consistent with the fact that, because of the rapid breakdown, no appreciable amount of PAF remained in the conditioned medium of PAF-treated cells. Although mouse bone marrow cells did not respond to PAF unlike guinea pig cells, their DNA synthesis was significantly enhanced by the conditioned medium of PAF-treated guinea pig bone marrow cells. Thus, some newly generated factor(s) distinct from the originally inoculated PAF seemed to modulate the bioactions of PAF on bone marrow cells. An appreciable amount of PAF was produced by calcium ionophore-treated guinea pig bone marrow cells. These findings indicate that PAF synthesized in guinea pig bone marrow cells induces generation in the cells of some factor(s) which affects proliferation or microbicidal activity. Presented at The Third International Conference on Platelet-Activating Factor and Structurally Related Ether Lipids, Tokyo, Japan, May 1989.