An overview on chlorophylls and quinones in the photosystem I-type reaction centers.

Minor but key chlorophylls (Chls) and quinones in photosystem (PS) I-type reaction centers (RCs) are overviewed in regard to their molecular structures. In the PS I-type RCs, the prime-type chlorophylls, namely, bacteriochlorophyll (BChl) a' in green sulfur bacteria, BChl g' in heliobacteria, Chl a' in Chl a-type PS I, and Chl d' in Chl d-type PS I, function as the special pairs, either as homodimers, (BChl a')(2) and (BChl g')(2) in anoxygenic organisms, or heterodimers, Chl a/a' and Chl d/d' in oxygenic photosynthesis. Conversions of BChl g to Chl a and Chl a to Chl d take place spontaneously under mild condition in vitro. The primary electron acceptors, A (0), are Chl a-derivatives even in anoxygenic PS I-type RCs. The secondary electron acceptors are naphthoquinones, whereas the side chains may have been modified after the birth of cyanobacteria, leading to succession from menaquinone to phylloquinone in oxygenic PS I.

Comparison between the free-radical-scavenging activities with vitamin E and ubiquinol in biological systems based on their reaction rates: a research account.

Detailed kinetic studies have been performed for the reaction of aroxyl (ArO.) radical with vitamin E (alpha-, beta-, gamma-, delta-tocopherol, TocH), ubiquinol-10, and related antioxidants in micellar solution, using a stopped-flow spectrophotometer. The second-order reaction rates (ks) obtained increased in the order of hydroquinone < tocol

Lipid and fatty acid composition of mesocarp and seed of avocado fruits harvested at northern range in Japan.

The lipid and fatty acid composition of the mesocarp and seed of avocado fruit grown and harvested in Japan, which is located at the northern range of the avacado, was investigated and compared to an imported avocado purchased commercially. The potential of the avocado mesocarp as an agricultural product in Japan was also explored. Total lipids (TL) accounted for approximately 20% of the mesocarp. Further analysis showed that the neutral lipid (NL) fraction accounted for at least 95% of the TL, and almost 90% of NL was triacylglycerol. Monoenoic acids accounted for at least 65% of the total fatty acids, and oleic acid, which is regarded as an especially important functional component of avacado accounted for approximately 50% of the monounsaturated fatty acids. A comparison of the Japanese avocado cultivars and an imported avocado cultivar in the present study revealed no significant differences in the lipid and fatty acid compositions. Therefore, production of avocado fruit, which is rich in various nutritional components, is expected to be increased on a larger number of farms in Japan in the future. It is believed to be necessary to carry out further verification, such as the establishment of a cultivation technique adoptable to Japan, examination of optimal soil and land features, and cultivar selection.

Kinetic study of the tocopherol regeneration reaction by biological hydroquinones in micellar solution.

The rate constants (kr) of the regeneration reaction of 7-t-butyl-5-isopropyltocopheroxyl with ubiquinol-10 (UQ10H2), ubiquinol-0 (UQ0H2), alpha-, beta-, and gamma-tocopherolhydroquinones (alpha-, beta-, gamma-TQH2), 2,3,5-trimethyl-1,4-hydroquinone (TMQH2), vitamin K3 hydroquinone (VK3H2), and vitamin C (Vit C) have been measured in 2-propanol/water and micellar solutions by a stopped-flow spectrophotometer. The kr values of these hydroquinones (HQs) in micellar solution remained constant at pHs of 6-9 and increased rapidly by increasing the pH value. The kr values decreased in the order of VK3H2 > gamma-TQH2 > or = alpha-TQH2 > beta-TQH2 > or = UQ10H2 > or = TMQH2 > UQ0H2 >> Vit C at pHs of 6-9. These HQs are dibasic acids and can exist in three different molecular forms, depending on pH. By comparing the kr values with the mole fraction of each molecular form of the HQs, the reaction rate kr1 for the undissociated form, kr2 for the monoanion, and kr3 for the dianion and the pKa1 and pKa2 values were determined. It has been found that the kr values of UQ10H2, alpha-TQH2, beta-TQH2, and gamma-TQH2 (plastoquinol model) are 460, 1430, 494, and 1530 times larger than that of Vit C at pH 7.0, respectively, although the values are similar to that of Vit C in 2-propanol/water. The biological HQs and Vit C coexist in many tissues of animals and plants, and thus, the relative antioxidant activities of HQs and Vit C have been tentatively discussed based on the products of kr values by concentrations in several tissues. The results suggest that these HQs show high activity for the tocopherol regeneration in biological systems.

Comparison of inter-twin concordance in symptoms of temporomandibular disorders: a preliminary investigation in an adolescent twin population.

There is controversy as to the genetic contribution to the pathogenesis of temporo-mandibular disorders (TMD). Several reports reveal a marked familial aggregation in the signs and symptoms of TMD, while others do not. Therefore, our goal was to investigate the hypothesis using a sophisticated research design, which was a well-known genetic survey inter-twin concordance assessment in the symptoms of TMD. This study is the first step to survey TMD symptoms of a twin group in junior and high schools as a preliminary trial. The 63 twins were asked to participate in this study in junior and senior high schools affiliated with the University of Tokyo, Japan, schools which kept ten twins in each grade for the purpose of several genetic survey programs. After excluding incomplete filling out of questionnaire sheets and data from male-female pairs, 43 monozygotic (MZ) (15.3+/-1.7 yrs, male/female = 17/26 pairs) and nine dyzygotic (DZ) (15.2+/-1.8 yrs, male/female = 6/3 pairs) twins were studied. Outcomes consisted of a prevalidated 14-item self-administered questionnaire, which assessed proband- and pair-wise concordance levels in the MZ and DZ twins. These results demonstrated that the MZ twins had a higher tendency of inter-twin concordance than DZ twins in terms of jaw pain in wide mouth opening (proband-wise concordance = 66.7% in MZ, 0% in DZ), difficulty in mouth opening (20% in MZ, 0% in DZ) and difficulty in mouth closing (50.0% in MZ, 33.3% in DZ), while there was no significant difference between the MZ and DZ concordance levels in other general health-related and behavior-related items, except toothache. However, the pair-wise concordance rates of jaw pain in wide mouth opening and difficulty in mouth opening in the MZ twins were not significantly higher compared to the DZ rate. Possibly, a genetic factor contributed to the pathogenesis of TMD in an adolescent population. The sample size needs to be increased, and there are plans to survey the next sample in the same schools.

Structure-activity relationship of the free-radical-scavenging reaction by vitamin E (alpha-, beta-, gamma-, delta-Tocopherols) and ubiquinol-10: pH dependence of the reaction rates.

The reaction rates (ks) of vitamin E (alpha-, beta-, gamma-, delta-tocopherols, TocH), ubiquinol-10, and related antioxidants (tocol, ubiquinol-0, and hydroquinone) with aroxyl (ArO(.-)) radical have been measured in micellar solution by stopped-flow spectrophotometer. The ks values increased in the order of hydroquinone < tocol < delta-TocH < ubiquinol-0 < gamma-TocH approximately beta-TocH < ubiquinol-10 < alpha-TocH at pH 4 approximately 8. The antioxidants which have lower oxidation potentials showed higher reactivities. The ks values of alpha-, beta-, gamma-, delta-tocopherol, and tocol remained constant between pH 4 and 10, and decreased rapidly at pH 11 approximately 12 by increasing pH value. From the pH dependence of ks values, the pKa values (= 13.1 approximately 12.6) have been determined for these tocopherols. The ks values of ubiquinol-10 also remained constant between pH 4 and 9, and increased rapidly at pH 9.5. Ubiquinol-10 is dibasic acid and can exist in three different molecular forms, depending on the pH value. By comparing the ks values with the mole fraction of each molecular form of ubiquinol-10, the reaction rate ks1 (= 1.21 x 10(5) M(-1)s(-1)) for the undissociated form, ks2 (= 1.04 x 10(6) M(-1)s(-1)) for monoanion and ks3 (= 0 M(-1)s(-1)) for dianion, and the pKa1 and pKa2 values (= 11.4 and 12.7) were determined. The ks2 value is 8.6 times as large as the ks1 value. Similar analyses were performed for ubiquinol-0 and hydroquinone. It was found that the relative ratio of ks values (100:21:20:2.9) of alpha-, beta-, gamma-, delta-tocopherols in micellar dispersion has good correlation with the relative biopotency ratios for rat fetal resorption, rat hemeolysis, and chicken muscle dystrophy. The relative antioxidant activities of alpha-tocopherol and ubiquinol-10 have been discussed based on the ks values obtained and their concentrations in serum and several tissues (heart, muscle, liver, kidney, and brain).

Hypoxia-induced changes in tight junction permeability of brain capillary endothelial cells are associated with IL-1beta and nitric oxide.

We examined whether hypoxia alone could produce changes in the permeability of brain capillary endothelial cells (EC) and whether a stimulation of hypoxic status alters the gene expression of occludin and glucose transporter 1 (GLUT1). Exposure of EC to hypoxia resulted in increased permeability, with the greatest decrease in transendothelial electrical resistance (TER) at 40 h. Moreover, hypoxia alone induced the expression of both mRNA in EC. Furthermore, we found that interleukin-1 (IL-1)beta, glutamate, hydrogen peroxide (H2O2), and sodium nitroprusside (SNP) induced the expression of mRNA for occludin and GULT1 under normoxic condition. The decrease in TER due to hypoxia was inhibited on addition of an anti-IL1 antibody and nitric oxide synthase (NOS) inhibitor in EC. These results indicate that the expression of occludin and GLUT1 mRNA is sensitive to exposure to hypoxia and that the changes of permeability in EC are associated with IL-1beta and NO.

Sphingosine 1-phosphate induces the production of glial cell line-derived neurotrophic factor and cellular proliferation in astrocytes.

Sphingosine 1-phosphate (S1P) is a platelet-derived bioactive sphingolipid that evokes a variety of biological responses. To understand the role of S1P in the central nervous system, we have examined the effect of S1P on the production of glial cell line-derived neurotrophic factor (GDNF) and growth regulation of cortical astrocytes from rat embryo. Moreover, we examined the possibility that the expression of GDNF is regulated differently in cultured astrocytes from the stroke-prone spontaneously hypertensive rat (SHRSP) than in those from Wistar kyoto rats (WKY). The mRNA expression was quantitated by RT-PCR based on the fluorescent TaqMan methodology. A new instrument capable of measuring fluorescence in real time was used to quantify gene amplification in astrocytes. GDNF protein was investigated by enzyme-linked immunosorbent assay. S1P induced the expression of GDNF mRNA and the production of GDNF protein in a dose-dependent manner in WKY astrocytes. Moreover, S1P increased cell numbers and induced the proliferation of astrocytes. In addition, the level of mRNA expression and protein production of GDNF was significantly lower in SHRSP than WKY astrocytes following exposure to S1P. These findings revealed that S1P augments GDNF protein production and cellular growth in astrocytes. Also, our results indicate that production in SHRSP astrocytes was attenuated in response to S1P compared with that observed in WKY. We conclude that S1P specifically triggers a cascade of events that regulate the production of GDNF and cell growth in astrocytes. Our results also suggest that the reduced expression of GDNF caused by S1P is a factor in the stroke proneness of SHRSP.