κ-卡拉胶琥珀酰基化衍生物的抗氧化活性研究

对κ-卡拉胶进行酸降解得到三种卡拉胶低聚糖,并进一步琥珀酰基化得到分子量分别为2720、4000和5960的κ-卡拉胶琥珀酰衍生物(A、B和C)。对产物进行FT-IR表征,并测得其琥珀酰基取代度(DS)分别为0.61、0.29和0.83。检测了三种κ-卡拉胶琥珀酰衍生物对超氧阴离子自由基O2.-、DPPH自由基、羟基自由基.OH以及过氧化氢的清除活性。结果表明:随着取代度的增加,其清除超氧阴离子自由基O2.-和DPPH自由基的能力增强;随着分子量的增加,其清除羟基自由基.OH和过氧化氢的能力增强。这可能与衍生物的羟基含量、取代基团的性质以及取代度等因素有关。     

Mechanism of action of DNA-hydrolyzing antibodies to DNA from blood of patients with systemic lupus erythematosus

Four fractions of IgG antibodies to native DNA (nDNA) were obtained from blood of patients with systemic lupus erythematosus (SLE). These antibodies displayed a thermostable DNA-hydrolyzing activity and were different in affinity for DNA-cellulose and sorption on DEAE-cellulose. DNA-hydrolyzing antibodies to nDNA are metal-dependent endonucleases, cause mainly single-strand breaks in DNA, and are active over a wide range of pH. By atomic-force microscopy, three-dimensional images of DNA complexes with DNA-hydrolyzing antibodies to nDNA were obtained with nanometer resolution, and a nonprocessive action mechanism was shown for the DNase activity of antibodies to nDNA.     

Regional muscle oxygenation differences in vastus lateralis during different modes of incremental exercise

Background

Near infrared spectroscopy (NIRS) is used to assess muscle oxygenation (MO) within skeletal muscle at rest and during aerobic exercise. Previous investigations have used a single probe placement to measure MO during various forms of exercise. However, regional MO differences have been shown to exist within the same muscle which suggests that different areas of the same muscle may have divergent MO. Thus, the aim of this study was to examine whether regional differences in MO exist within the same muscle during different types of incremental (rest, 25, 50, 75, 100 % of maximum) exercise (1 leg knee extension (KE), 2 leg KE, or cycling).

Methods

Nineteen healthy active males (Mean ± SD: Age 27 ± 4 yrs; VO_2max: 55 ± 11 mL/kg/min) performed incremental exercise to fatigue using each mode of exercise. NIRS probes were placed on the distal and proximal portion of right leg vastus lateralis (VL). Results were analyzed with a 3-way mixed model ANOVA (probe × intensity × mode).

Results

Differences in MO exist within the VL for each mode of exercise, however these differences were not consistent for each level of intensity. Comparison of MO revealed that the distal region of VL was significantly lower throughout KE exercise (1 leg KE proximal MO – distal MO = 9.9 %; 2 leg KE proximal MO – distal MO = 13 %). In contrast, the difference in MO between proximal and distal regions of VL was smaller in cycling and was not significantly different at heavy workloads (75 and 100 % of maximum).

Conclusion

MO is different within the same muscle and the pattern of the difference will change depending on the mode and intensity of exercise. Future investigations should limit conclusions on MO to the area under assessment as well as the type and intensity of exercise employed.

     

Phytoplankton of Lake Solenoye (Omsk) as a promising source of bioresources

The mass vegetation of the cyanobacteria Spirulina fusiformis Woronich. was discovered during examination of the shallow Lake Solenoye, situated in the territory of Omsk. Large resources of the raw spirulina biomass in summer make it possible to use the lake as a source of valuable raw material.     

锌对铅染毒新生大鼠成骨细胞增殖分化的影响

目的:探讨铅锌联合染毒对乳鼠颅骨成骨细胞增殖分化的影响。方法:分离并培养原代成骨细胞,加入不同浓度铅、锌培养48h,检测其对成骨细胞增殖的作用;用碱性磷酸酶试剂盒检测ALP活力。结果:在染铅48h后,当铅浓度≥10μmol/L时,细胞增殖功能下降(P<0.05);加锌干预48h后,铅+锌组细胞增殖功能均高于各自单独染铅组,其中铅(1μmol/L、10μmol/L)+锌(50μmol/L)组、铅(10)+锌(100)组与对照组间的差异具有统计学意义(P<0.05)。铅干预48h后,100μmol/L铅组的ALP活力显著下(P<0.05),给予锌干预的铅锌联合染毒组,各组ALP活力均有增加,其中铅(1μmol/L、10μmol/L)+锌(50μmol/L)组ALP活力均高于对照组,而铅(100μmol/L)+锌(50μmol/L)组ALP活力低于对照组,差异均有统计学意义(P<0.05)。结论:铅对成骨细胞有毒性作用,影响其增殖和分化功能;50μmol/L锌在一定程度上可以拮抗铅对成骨细胞增殖和分化功能的损伤,且对ALP活力的作用更显著,为铅中毒骨病的防治提供一定的科学依据。     

Morphology and coexistence of congeneric ectoparasite species: reinforcement of reproductive isolation?

Assuming that differences or similarities in morphology among congeneric parasite species living in the same habitat are not a random pattern, several hypotheses explaining morphological differences were tested: (i) reproductive isolation, (ii) niche restriction resulting from competition, and (iii) niche specialization. Congeneric monogenean (platyhelminth) ectoparasites parasitizing the gills of one host species were used as an ecological model. Morphometric distances of the attachment organ and morphometric distances of the copulatory organ between species pairs were calculated, Levin's niche size and Renkonen niche overlap indices were applied. Our results support the prediction that the function of niche segregation is to achieve reproductive isolation of related species in order to prevent hybridization (reinforcement of reproductive barriers). Parasite species living in the same niche differ greatly in the size of copulatory organ. Moreover, species coexistence is facilitated by an increase in morphometric distances of copulatory organ and niche centre distances. Our results also show that species living in overlapping niches have similar attachment organs, which supports the prediction that morphologically similar species have the same ecological requirements within one host and suggests small effects of interspecific competition for the evolution of morphological diversity of attachment organs. Specialist adaptations also seem to facilitate species coexistence and affect the niche distribution within host species. Parasite species that can colonize more than one host species, i.e. generalists, occupy more distant niches within host species than strictly host-specific parasites. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 76, 125–135.     

Activity of glutathione-dependent enzymes, catalase and superoxide dismutase in the liver and myocardium of rats with vitamin A deficiency

The alimentary deficiency of vitamin A causes marked shifts in the metabolism of GSH: the levels of GSH, GSSG and cysteine in the liver increase, while the activities of glutathione-S-transferase (using glycerol as substrate) and gamma-glutamyltransferase in the liver show a rise. At the same time, vitamin A deficiency causes a decrease of the glutathione peroxidase and catalase activity in the liver. The data obtained are discussed in terms of the role of GSH and enzymes of GSH metabolism in the protection of cells against the damaging influence of lipid peroxidation.     

Effect of a highly dispersed copper powder on superoxide dismutase and glutathione peroxidase activities in experimental myocardial infarct

Administration of highly dispersed copper powder in a dose 0.2 mg/kg three days before modelled coronary-occlusion myocardial infarction caused transitory increase in activity of antioxidant enzymes--superoxide dismutase and glutathione peroxidase in the necrotic zone of myocardium of rats, and also staunch increase in the activity of these enzymes in noninfarction region.     

Anti-necrosogenic action of natural and synthetic antioxidants in coronary occlusive myocardial infarct

The synthetic liposoluble antioxidant BAT. 120 mg/kg, was found to produce markedly protective effects in a rat model of coronary occlusive myocardial infarction, whereas the water soluble BAT analogue, 4-Oxy-3,5-ditretbutylphenyl phosphonic acid sodiate (SFN-6), 100 mg/kg, displayed no protective effects. The natural antioxidant beta-carotene capable of displaying antioxidative activity at low partial O2 pressures was shown to reduce the size of postinfarct scar by 34% when given in a dose of 20 mg/kg. The synthetic antioxidants, BAT and SFN-6 given in doses of 100 to 120 mg/kg each decreased antioxidant enzyme activities in the intact or infarct-related myocardium. beta-carotene was found to lack inhibitory effects on the myocardial antioxidant enzymes, thus enhancing its cardioprotective properties.