We previously reported that benzo-(a)-pyrene (BP) and methylcholanthrene (MC) emitted blue-colored ultra-weak chemiluminescence (CL) during the metabolism in a post mitochondrial fraction system. In this present study, we used a single-photon counting system (SPC) equipped with a photomultiplier having a spectral response in the red-color region to detect the CL from BP, MC, and 3-nitrofluoranthene (3-NF). As a result, we discovered that a novel red-region CL was emitted immediately after initiation of the metabolic reaction in this system. In the case of BP and MC, each had a double phase CL emission; that is, they initially emitted red CL, which was detected by the SPC, and thereafter, blue CL, which was detected with an OX-71 chemiluminescence analyzer. However, in the case of 3-NF, although strong red CL emission was recorded, no blue-colored CL appeared to be emitted. The emissions of red CL were increased in systems in which D2O was added (final concentration of 66%), and decreased by the addition of β-carotene or α-tocopherol. This result suggests that the main cause of CL was singlet oxygen.
Azelastine, an anti-allergic agent, completely overcame the resistance to vincristine (VCR) of a VCR-resistant subline (P388/VCR) of P388 murine leukemia cells (P388). Considering our previous result [Yamamoto et al. (1989) J. Clin. Biochem. Nutr., 6, 205] that the drug overcame the resistance to adriamycin (ADM) of an ADM-resistant subline (P388/ADM) of P388, we concluded that the drug circumvents multidrug resistance of leukemia cells. This circumvention by azelastine is ascribable to the accumulation of anticancer agent in drug-resistant leukemia cells. As for the mechanism of the accumulation, a metabolic inhibition experiment showed that the accumulation is not due to increased influx of the drug into the cells but due to an azelastine-effected decrease in the efflux of the drug from the cells. Thus, the effect of azelastine on the binding of P-glycoprotein in plasma membrane fraction with VCR was examined. [3H] VCR binding to the membrane fraction prepared from an ADM-resistant human myelogenous leukemia cell line (K562/ADM) was inhibited by azelastine in a concentration-dependent manner. These results imply that azelastine circumvents multidrug resistance through, at least partly, the inhibition of the efflux of anti-cancer drug from leukemia cells by its binding to P-glycoprotein. We further noted that the treatment with azelastine in combination with VCR significantly prolonged the survival of P388/VCR-bearing mice as compared with those given VCR alone.
Male Zucker rats either genetically obese (fa/fa) or lean (Fa/-) were fed a semi-purified diet containing either cornstarch or amylomaize starch (Eurylon 7R) rich in amylose (70%). Obese rats were hyperlipidemic (cholesterol, 3.27±0.18; triglycerides, 2.11±0.12g/liter), when compared with lean rats (cholesterol, 1.13±0.03; triglycerides, 0.75±0.05g/liter). The amylomaize diet did not reduce the body weight of the Zucker rats. However, it decreased weight, esterified cholesterol, and triglyceride content of the liver in both lean and obese rats. The amylomaize diet decreased plasma cholesterol levels of obese rats (-42%) and lean rats (-30%), while plasma triglyceride levels were significantly decreased only in the lean rats (-43%). The cholesterol content of chylomicrons, VLDL, LDL1 (1.006-1.040), and LDL2 (1.040-1.063, which contains apo E-rich HDL) was reduced by 40 to 50%, while that of HDL was reduced by only 20% (lean) or 23% (obese). Diet containing amylose-rich starch therefore constitutes a promising new way of nutritional control of hyperlipidemias.
Analyses of rats diurnal/nocturnal feeding behaviour were made according to the caloric density of the lipid ration. Adult male Sprague-Dawley rats were simultaneously offered three pure macronutrient diet rations: protein, carbohydrate, and lipid. The last was either kept isocaloric to protein and carbohydrate rations or was hypercaloric. Measurements of the food intake were recorded at 12-h intervals with respect to the dark phase and to the light phase of the circadian cycle (24h). Rats fed the hypercaloric lipid diet ration showed a significantly higher total energy intake compared with animals fed the isocaloric lipid diet ration. Also, in the hypercaloric group, the percentage of energy ingested as protein was significantly higher during both the light and dark phases, whereas the percentage of energy ingested as carbohydrate was significantly lower during the light phase and the 24-h cycle when compared with that of the isocaloric group. These results indicate that the caloric density of the lipid diet ration has differential effects on the diurnal/nocturnal energy intake and macronutrient choice and suggest that these feeding patterns may modify the outcome of experiments using macronutrient diet rations with different caloric density.
To evaluate lipid peroxide metabolism in neonatal rats during suckling, we studied developmental changes in whole body lipid peroxidation by measurement of thiobarbituric acid-reactive substances (TBARS) determined as malondialdehyde. Whole body TBARS contents were very low immediately after birth but increased sharply at 3-9 days, peaked at 9-15 days, and then remained unchanged until 21 days. The feeding of a skimmed milk diet to neonates between 17 and 20 days old sharply decreased their whole body TBARS contents at 20 days as compared with those at 16 days, however, this was not observed by the feeding of an artificial milk diet containing 3g of soybean oil/100g diet. In vitro ethane production by liver and brain homogenates and in vivo breath ethane levels in expired air were higher at 20 or 21 days than at 10 days after birth. These results suggest that lipid peroxide formation in neonatal rats increases shortly after birth and that its degradation and/or excretion may increase during the latter period of suckling.
The effects of Fe2+ and Cu2+ on prostaglandin (PG) synthesis and catabolism in rabbit gastric antral mucosal slices have been compared. Fe2+ markedly promoted the lipid peroxidation of gastric mucosal slices. The lipid peroxidation induced by Fe2+ inhibited the formation of all four PGs examined (PGE2, PGF2α, 13, 14-dihydro-15-keto PGE2 and 13, 14-dihydro-15-keto PGF2α) to a similar extent. While Cu2+ produced only a small increase in lipid peroxidation, it had a powerful stimulatory effect on PGE2 and PGF2α formation. Cu2+ induced no change in the formation of 13, 14-dihydro-15-keto PGE2 and 13, 14-dihydro-15-keto PGF2α. Moreover, tert-butyl hydroperoxide stimulated the formation of all four PGs at low concentrations (5 and 10μM), but inhibited it at a high concentration (1, 000μM). These results suggest that Cu2+ has the potential to increase the levels of biologically active PGs in gastric mucosa by affecting the activities of both PG cyclo-oxygenase and PG-catabolizing enzymes.
We examined the effect of simultaneous treatment with 6-diazo-5-oxo-L-norleucine (DON), a glutamine antagonist, and L-cycloserine, a transaminase inhibitor, on Yoshida sarcoma-bearing rats, with the aim of achieving inhibition of both glutamine catabolism and glutamate synthesis. L-Cycloserine, in a dosage of 1-30mg/kg, was intraperitoneally administered to Yoshida sarcoma-bearing rats, but the administration of L-cycloserine alone did not show any significant effect on the tumor weight. However, combined treatment with DON (1mg/kg) caused a dose-dependent reduction in the tumor weight. Amino acid analysis of the tumor tissue, performed 24h after these treatments in order to confirm their influences on amino acid metabolism in the tumor, showed that the increased glutamate level seen after treatment with DON in a previous study was suppressed by simultaneous administration of DON and 10mg/kg of L-cycloserine. These results suggest that pooled glutamate in the tumor tissue plays some role in resistance to the tumor-reducing activity of this glutamine antagonist. This, in turn, suggests that concurrent inhibition of glutamate production and blockage of glutamine utilization might result in enhanced tumor reduction in a clinical study.
Changes were identified in the glycosylation profiles of immunoglobulin G (IgG) from 15 patients with myotonic dystrophy (MyD). IgG oligosaccharides released by glycoamidase A were labeled with the fluorescent compound 2-aminopyridine and separated by HPLC. The structural changes in the oligosaccharide moieties of IgG in these patients were characterized by marked increases in agalactosyl oligosaccharides and decreases in digalactosyl oligosaccharides. Furthermore, the ratio of the level of Galβ4GlcNAcβ2Manα6(GlcNAcβ2Manα3)Manβ4GlcNAcβ4(Fucα6)GlcNAc to the level of GlcNAcβ2Manα6(Galβ4GlcNAcβ2Manα3)Manβ4GlcNAcβ4(Fucα6)GlcNAc was 1.3 in patients with MyD, while it was 2.3 in controls. These data suggest that increases in agalactosyl oligosaccharides of IgG occur in patients with MyD and it is supposed to be resulted from functional disturbance in the activity of β1, 4-galactosyltransferase.