Effect of beta-carotene on the transformation of tyrosine by nitrogen dioxide and peroxynitrous acid

In the NO2-exposure of tyrosine in 70% dioxane/phosphate buffer (pH 7.4), beta-carotene enhanced the degradation of tyrosine and/or 3-nitrotyrosine produced, whereas alpha-tocopherol and ascorbyl palmitate inhibited the transformation of tyrosine into 3-nitrotyrosine. Generation of certain active species in the interaction of beta-carotene with NO2 was suggested. Ascorbyl palmitate effectively and alpha-tocopherol slightly inhibited the transformation of tyrosine in the NO2-exposure in the presence of beta-carotene. In the reaction of tyrosine with ONOO-/ONOOH, beta-carotene enhanced the degradation of 3-nitrotyrosine produced suggesting generation of certain active species, whereas alpha-tocopherol and ascorbyl palmitate completely suppressed the transformation of tyrosine into 3-nitrotyrosine.     

Increased release of free Fe ions in human erythrocytes during aging in the circulation

We investigated whether free Fe ions were released in erythrocytes during aging process in the circulation. Young and senescent erythrocytes were separated from freshly drawn human blood by Percoll density gradient centrifugation. Two different methods were employed for determination of free Fe ions in erythrocytes, desferrioxamine (DFO) method and bleomycin method. DFO-chelatable Fe ions were detected in whole erythrocytes from 2 donors, and the DFO-chelatable free Fe ion levels in senescent erythrocytes were higher than those in young erythrocytes. Bleomycin-sensitive Fe ions, which was rather lower than DFO-chelatable Fe ions, were also detected in whole erythrocytes from 5 donors, and the free Fe ion levels in senescent erythrocytes were also higher than those in young erythrocytes. Free Fe ions may be derived from oxidative damage of hemoglobin, because treatment of whole erythrocytes or purified oxyhemoglobin with hydrogen peroxide gave increased free Fe ions. The results indicated that free Fe ions were released from erythrocytes during aging process in the circulation. Released free Fe ions would promote oxidative damages of the cells during aging process.     

Kinetic studies on the hydrogen peroxide elimination by cultured PC12 cells: rate limitation by glucose-6-phosphate dehydrogenase

Long chain acyl-Coenzyme A esters (acyl-CoAs) are key substrates in many enzymic reactions of lipid metabolism. Due to their amphiphilic nature, the membrane localization of these molecules cannot be established by subcellular membrane fractionation and usual biochemical studies. We have developed another approach based on ultrastructural immunogold cytochemistry. To preserve the acyl-CoA membrane content, the plant material was freeze substituted and cryoembedded after short aldehyde fixation followed by quick freezing. Using Arabidopsis thaliana root cells and specific antibodies raised against acyl-CoAs, we show that acyl-CoAs are mainly localized in endoplasmic reticulum membranes.Our results demonstrate the value of cryo-methods for the accurate localization of labile metabolites in plant cells.     

Content and chemical compositions of cerebrosides in lactose-assimilating yeasts

Cerebrosides were found in ten lactose-assimilating yeasts. Representative component ceramide moieties of cerebrosides from nine of these yeasts contained 9-methyl-4-trans, 8-trans-sphingadienine, and 2-hydroxy fatty acid with carbon chain lengths of 16 or 18. The major ceramide moieties in Brettanomyces anomalus, however, differed from those in other yeasts, and were predominately moieties containing 2-hydroxymyristic acid. Thus we found that various cerebroside molecular species are present in yeasts.     

Testing the hypothesis on the relationship between aerodynamic roughness length and albedo using vegetation structure parameters

Surface albedo (α) and aerodynamic roughness length (z ₀), which partition surface net radiation into energy fluxes, are critical land surface properties for biosphere–atmosphere interactions and climate variability. Previous studies suggested that canopy structure parameters influence both α and z ₀; however, no field data have been reported to quantify their relationships. Here, we hypothesize that a functional relationship between α and z ₀ exists for a vegetated surface, since both land surface parameters can be conceptually related to the characteristics of canopy structure. We test this hypothesis by using the observed data collected from 50 site-years of field measurements from sites worldwide covering various vegetated surfaces. On the basis of these data, a negative linear relationship between α and log(z ₀) was found, which is related to the canopy structural parameter. We believe that our finding is a big step toward the estimation of z ₀ with high accuracy. This can be used, for example, in the parameterization of land properties and the observation of z ₀ using satellite remote sensing.     

Longevity-associated mitochondrial DNA 5178 C/A polymorphism modulates the effects of coffee consumption on erythrocytic parameters in Japanese men: an exploratory cross-sectional analysis

Background

Mitochondrial DNA 5178 cytosine/adenine (Mt5178 C/A) polymorphism reportedly modulates the effects of coffee consumption on the risk of hypertension, dyslipidemia and abnormal glucose tolerance. The objective of this analysis was to investigate whether Mt5178 C/A polymorphism modifies the effects of coffee consumption on erythrocytic parameters in male Japanese health check-up examinees.

Methods

A total of 436 men (mean age ± standard deviation, 54.1 ± 7.8 years) were selected from among individuals visiting the hospital for regular medical check-ups. After Mt5178 C/A genotyping, an exploratory cross-sectional analysis assessing the joint effects of Mt5178 C/A polymorphism and coffee consumption on red blood cell counts, hematocrit and hemoglobin was conducted.

Results

For Mt5178C genotypic men, after adjustment for age, body mass index, alcohol consumption, habitual smoking and green tea consumption, coffee consumption significantly decreased red blood cell counts (P for trend = 0.022) and hemoglobin (P for trend = 0.035). The risk of anemia, defined as hemoglobin of <14 g/dL, after the aforementioned adjustment, appeared to depend on coffee consumption (P for trend = 0.078), and the adjusted odds ratio for anemia was significantly higher in men who consumed ≥4 cups of coffee per day than in those who consumed <1 cup per day (odds ratio = 3.771, 95% confidence interval: 1.088 to 13.06, P = 0.036). For Mt5178A genotypic men, coffee consumption possibly reduced the risk of anemia (P for trend = 0.049). However, after the aforementioned adjustment, the statistical significance disappeared (P for trend = 0.137).

Conclusions

This exploratory cross-sectional analysis suggests that Mt5178 C/A polymorphism modulates the effects of coffee consumption on erythrocytic parameters and the risk of anemia in male Japanese health check-up examinees.     

Antimutagenicity of cinnamaldehyde and vanillin in human cells: Global gene expression and possible role of DNA damage and repair

Vanillin (VAN) and cinnamaldehyde (CIN) are dietary flavorings that exhibit antimutagenic activity against mutagen-induced and spontaneous mutations in bacteria. Although these compounds were antimutagenic against chromosomal mutations in mammalian cells, they have not been studied for antimutagenesis against spontaneous gene mutations in mammalian cells. Thus, we initiated studies with VAN and CIN in human mismatch repair-deficient (hMLH1(-)) HCT116 colon cancer cells, which exhibit high spontaneous mutation rates (mutations/cell/generation) at the HPRT locus, permitting analysis of antimutagenic effects of agents against spontaneous mutation. Long-term (1-3 weeks) treatment of HCT116 cells with VAN at minimally toxic concentrations (0.5-2.5mM) reduced the spontaneous HPRT mutant fraction (MF, mutants/10(6) survivors) in a concentration-related manner by 19-73%. A similar treatment with CIN at 2.5-7.5microM yielded a 13-56% reduction of the spontaneous MF. Short-term (4-h) treatments also reduced the spontaneous MF by 64% (VAN) and 31% (CIN). To investigate the mechanisms of antimutagenesis, we evaluated the ability of VAN and CIN to induce DNA damage (comet assay) and to alter global gene expression (Affymetrix GeneChip) after 4-h treatments. Both VAN and CIN induced DNA damage in both mismatch repair-proficient (HCT116+chr3) and deficient (HCT116) cells at concentrations that were antimutagenic in HCT116 cells. There were 64 genes whose expression was changed similarly by both VAN and CIN; these included genes related to DNA damage, stress responses, oxidative damage, apoptosis, and cell growth. RT-PCR results paralleled the Affymetrix results for four selected genes (HMOX1, DDIT4, GCLM, and CLK4). Our results show for the first time that VAN and CIN are antimutagenic against spontaneous mutations in mammalian (human) cells. These and other data lead us to propose that VAN and CIN may induce DNA damage that elicits recombinational DNA repair, which reduces spontaneous mutations.     

Transformation of arylamines into direct-acting mutagens by reaction with nitrite

Arylamines including aniline (I), 1-naphthylamine (II), 2-naphthylamine (III), 2-aminofluorene (IV), 1-aminoanthracene (V) and 1-aminopyrene (VI) were treated with 4 equivalent amounts of nitrite at pH3 and 37 degrees C for 4 h. The reaction mixtures of I, IV, V and VI showed mutagenicity to Salmonella typhimurium TA98 and TA100 strains without metabolic activation. The numbers of His+ revertant colonies to TA98 strain were 110/0.05 mumole I, 970/0.055 mumole IV, 620/0.10 mumole V and 870/0.02 mumole VI. These arylamines were converted into mutagens with diazoquinone, diazonium and nitro functions depending on their structures. The mutagen from I was p-diazoquinone (I2). The mutagen from IV was highly unstable fluorene-2-diazonium salt (IV1). The mutagens from V were N3O3-introduced anthracene (V1-1) and 1-nitroanthracene (V2), and those from VI were unidentified nitro-introduced compound (VI1) and 1-nitropyrene (VI2).