Hydrogen Peroxide-dependent Synthesis of Flavonols in Mesophyll Cells of Vicia faba L.

Mesophyll cells of Vicia faba contain kaempferol and quercetinglycosides. When isolated mesophyll cells were treated with0.1 mM H₂O₂ for 2 h, the levels of these flavonols increasedby 10–70% of the control values (mean values, 19.6% and34.4% for kaempferol and quercetin glycosides, respectively).Such increases in levels of flavonols were also observed inisolated vacuoles of mesophyll cells. However, when mesophyllcells and vacuoles were treated with 10 mM H₂O₂₎degradationof flavonols was observed. These data suggest that H₂O₂ hastwo effects on the metabolism of flavonols: induction of theirsynthesis and stimulation of their oxidation. (Received March 6, 1989; Accepted July 10, 1989)     

The structure ofHLA-B35 suggests that it is derived fromHLA-Bw58 by two genetic mechanisms

The primary structure ofHLA-B51 andHLA-Bw52 suggested thatHLA-B51 was derived fromHLA-Bw52 by the combination of a genetic exchange withHLA-B8 and a point mutation. To investigate the evolution of theHLA-B5 cross reactive group, theHLA-B35 gene was cloned and the primary structure was determined.HLA-B35 is identical toHLA-Bw58 except in the α₁ domain. The α₁ domain ofHLA-B35 except Bw4/Bw6-associated amino acids is identical to that ofHLA-B51 ^*, which was suspected to be an intermediate gene betweenHLA-B51 andHLA-Bw52. These data suggest thatHLA-B35 has evolved fromHLA-Bw58 in two steps; an in vivo replacement of the α₁ domain withHLA-B51 and genetic exchange with one of theHLA-Bw6 genes. These three genes andHLA-Bw58 are postulated to share a common ancestor.     

Properties and fluctuations in vivo of rat liver antizyme inhibitor.

Antizyme inhibitor was highly purified from rat liver by using affinity chromatography. It has some structural resemblance to ornithine decarboxylase (ODC), as judged from Mr, immunoreactivity and reversible binding with antizyme. However, unlike hepatic amounts of ODC and ODC-antizyme complex, that of antizyme inhibitor did not show much fluctuation upon putrescine treatment, whereas it decreased as rapidly as ODC decay in the presence of cycloheximide. These results suggested that antizyme inhibitor is an independent regulatory protein rather than a derivative of ODC. Changes in hepatic amounts of antizyme inhibitor, antizyme and ODC upon feeding suggested that antizyme inhibitor may play a role in ODC regulation by trapping antizyme and thereby suppressing ODC degradation. A monoclonal antibody to rat liver antizyme inhibitor was obtained. This antibody was shown to be utilizable for a simple assay of antizyme-inhibitor activity in tissue extracts.     

Effect of volume expansion on hemodynamic variables in nephrectomized dogs

We have previously demonstrated that blood pressure elevation by acute blood volume expansion is volume-dependent during the infusion period and resistance-dependent in the post-infusion period in normal anesthetized dogs, and that such an increase in blood pressure is associated with a potentiation of the pressor response to norepinephrine. To evaluate the possible renal contribution to these hemodynamic changes, blood volume expansion was performed for 1 h with dextran dissolved in lactated Ringer's solution (20 ml/kg) in 15 nephrectomized dogs. The mean blood pressure, cardiac output and total peripheral resistance at the end of infusion were 126%, 225% and 60%, respectively; 3 h after volume expansion they were 126%, 151%, and 92% respectively. However, in 4 dogs, there was an increase in mean blood pressure (138%) 3 h after volume expansion. This was thought to result from an increase in the total peripheral resistance (133%) associated with the recovery of cardiac output (106%). The pressor response to norepinephrine (0.5 microgram/kg) was potentiated after volume expansion. These results indicate that the handling of volume by the kidney contributed to the maintenance of an elevated level of cardiac output. However, nephrectomy did not seem to interfere with the hemodynamic switching of the causative factor for blood pressure elevation from increased cardiac output to increased total peripheral resistance. Neither was the potentiation of pressor response to norepinephrine affected.     

Analysis of electrophoretic mobility histograms of mouse splenocytes and thymocytes during tumor growth and after combined chemotherapy and immunotherapy

Changes in electrophoretic mobility histograms of splenocytes and thymocytes were studied in plasmacytoma X5563-bearing mice as an indicator of response to treatment with mitomycin C (MMC) alone or combined with the immunomodulator Krestin (PSK). Tumor growth was inhibited by 80-90% in the MMC-treated and was further inhibited in the MMC and PSK-treated group. Electrophoretic mobility histograms of splenocytes were used to determine the fraction of cells having intermediate mobility between high mobility (T cells) and low mobility (B cells). This fraction of intermediate-mobility cells increased in tumor-bearing mice, but a normal electrophoretic mobility pattern was obtained following successful antitumor treatment. In the electrophoretic mobility histogram of thymocytes, on the other hand, the low-mobility cells (cortical thymocytes) decreased in number during tumor growth and were further reduced in the MMC-treated group. This reduction was less in the MMC and PSK-treated group. These results suggest that combined therapy with MMC and PSK prevents damage of the host defence mechanism and allows more efficient antitumor treatment. Analysis of electrophoretic mobility histograms of splenocytes and thymocytes using a fully automated cell electrophoretic instrument makes possible the rapid evaluation of the immunological effects of drug therapy of tumor-bearing mice.     

Comparison of growth properties of carrot hairy root in various bioreactors

Summary Growth properties of carrot hairy root cells in various bioreactors were investigated. A turbine-blade reactor and an immobilized rotating drum reactor were found to be advantageous for the hairy root culture because of a high oxygen transfer coefficient (k in L a). After 30 days of culture, 10 g/l of dry hairy root cells were obtained in both bioreactors and maximum growth rates (V _m ) were found to be 0.63 and 0.61 g/l per day for the turbine-blade reactor and immobilized rotating drum reactor, respectively. Specific growth rates () at various cultivation times were observed to be linearly proportional to X/k _l a for both bioreactor configurations where X is the cell concentration. The estimated specific oxygen uptake rate of 0.34 mmol O₂/g dry cells per hour compares fairly well with an experimental value of 0.3.     

Changes in polyamine-oxidizing capacity of peroxisomes under various physiological conditions in rats

Rat liver peroxisomal polyamine oxidase activity was determined under various physiological conditions by using the peroxidase method with phenol and 4-aminoantipyrine. N1-Acetylpolyamines such as N1-acetylspermine and N1-acetylspermidine were better substrates than the free polyamines. The polyamine oxidase activity in rat peroxisomes increased significantly when cell proliferation was high. The activity began to appear in fetal liver at the 16th approximately 18th day of pregnancy and peaked in neonatal liver on the first day (approx. 1.7-times higher than in adult liver). In regenerating rat liver, only polyamine oxidase activity among the peroxisomal enzymes tested was increased considerably 12 h after partial hepatectomy (approx. 2.8-fold over the control liver). Finally, the enzyme activity was significantly increased by administration of clofibrate, a peroxisome proliferator, which also causes hepatomegaly. In all cases, the increase in polyamine oxidase activity was not more than 3-fold. Since the level of polyamine oxidase activity in the normal liver is more than adequate in relation to the level of the substrates, the slight but significant increase under conditions of cell proliferation may have a role in modulating levels of polyamines in the proliferating liver tissue.     

The role of peroxisomal fatty acyl-CoA beta-oxidation in bile acid biosynthesis

The physiological role of the peroxisomal fatty acyl-CoA beta-oxidizing system (FAOS) is not yet established. We speculated that there might be a relationship between peroxisomal degradation of long-chain fatty acids in the liver and the biosynthesis of bile acids. This was investigated using [1-14C]butyric acid and [1-14C]lignoceric acid as substrates of FAOS in mitochondria and peroxisomes, respectively. The incorporation of [14C]lignoceric acid into primary bile acids was approximately four times higher than that of [14C]butyric acid (in terms of C-2 units). The pools of these two fatty acids in the liver were exceedingly small. The incorporations of radioactivity into the primary bile acids were strongly inhibited by administration of aminotriazole, which is a specific inhibitor of peroxisomal FAOS in vivo [F. Hashimoto and H. Hayashi (1987) Biochim. Biophys. Acta 921, 142-150]. Aminotriazole inhibited preferentially the formation of cholate, the major primary bile acid, from both [14C]lignoceric acid and [14C]butyric acid, rather than the formation of chenodeoxycholate. The former inhibition was about 70% and the latter was approximately 40-50%. In view of reports that cholate is biosynthesized from endogenous cholesterol, the above results indicate that peroxisomal FAOS may have an anabolic function, supplying acetyl CoA for bile acid biosynthesis.     

Dual loading of the fluorescent indicator fura-2 and 2,7-biscarboxyethyl-5(6)-carboxyfluorescein (BCECF) in isolated myocytes

Isolated rat heart myocytes were loaded with both the Ca2+ sensitive fluorescent probe fura-2/AM and the fluorescent pH indicator 2,7-biscarboxyethyl-5(6)-carboxyfluorescein (BCECF/AM). Changes in [Ca2+]i and pHi were measured simultaneously using digitized video fluorescence microscopy. In measurement of [Ca2+]i and pHi, the ratios of dual-loaded cells were not different from single-loaded cells. Using this method, [Ca2+]i and pHi in myocytes were 48 +/- 7 nM and 7.17 +/- 0.05. It is concluded that [Ca2+]i and pHi could be measured simultaneously in isolated myocyte using dual-loading of fura-2 and BCECF.     

Mitochondrial DNA polymorphism in native Philippine cattle based on restriction endonuclease cleavage patterns

An analysis of patterns of cleavage of mtDNA by restriction endonucleases was performed for nine individuals from the Philippine population of native cattle. MtDNA polymorphisms were detected in the restriction patterns generated by the following six enzymes,BamHI,BglII,EcoRV,HindIII,PstI, andScaI. The restriction patterns showing polymorphisms were distributed nonrandomly among the nine individuals examined from the Philippine population of native cattle, indicating the existence of two separate types of mtDNA. These two types of mtDNA are very different from each other, at the level of subspecies. Since the native Philippine cattle are considered to represent an admixture of European and Indian cattle, the two types of mtDNA must be derived from the mtDNAs of both varieties. The polymorphic sites in mtDNA have been located on a restriction map, and the nucleotide substitutions at some of the sites have also been estimated.