Inhibitory effect of ATP on proliferative signaling in immortalized human fibroblasts

AIM: To investigate the inhibitory effects of ATP on proliferation signaling in immortalized human fibroblasts. METHODS: Immortalized human fibroblasts were treated with ATP, ATP conbined with calcium or potassium channel antagonists, respectively. The intracelluar-free calcium ([Ca²⁺]i), inositol 1,4,5-trisphosphate(IP₃) levels and cell viability were detected at different time points. RESULTS: ATP significantly increased the [Ca²⁺]i and decreased the IP₃ level in immortalized human fibroblasts, especially at initial stage (P＜0.01) . Compared to ATP alone, the proliferation rates remarkably increased when calcium or potassium channel antagonists were used (P＜0.01, respectively) with ATP. CONCLUSION: The calcium and potassium channels and IP₃ involved in the inhibitory effects of ATP on the proliferative signaling in immortalized human fibroblasts.     

Quantitative analysis of inositol phosphate contents in oat products using an anion exchange chromatographic method

Oat has gained interest due to its high nutritional value. When utilising oat fractions rich in dietary fibre, their inositol phosphate (InsP, including phytate) content is considerably high due to the lack of active phytase in the kilned oat ingredients. The high InsP content is linked to decreased mineral absorption in the gut, but the mineral-binding ability of InsPs also results in antioxidativity and a decrease in starch hydrolysis, thus lowering glycaemic response. This study aimed to further develop an anion exchange liquid chromatographic method for quantification of different InsP forms from oat products and to study the changes in the InsP contents resulting from the differences in the ingredients or processes. The method was applicable for quantifying such InsP forms that can effectively bind minerals. The InsPs were stable at moderate temperatures and in the oat baking process, but a significant degradation occurred during the high-temperature treatments, extrusion, and bacterial fermentation.     

Interaction of phytases with minerals and availability of substrate affect the hydrolysis of inositol phosphates

The stability and activity of phytases in the soil environment may be affected by their sorption on soil particle surfaces and by substrate availability with important consequences for P cycling and nutrient bioavailability. This work evaluated the interaction of phytases with goethite, haematite, kaolinite, montmorillonite and two oxisol clays and investigated how this interaction is affected when myo-inositol hexakisphosphate (InsP₆) was sorbed on the mineral surfaces. phyA histidine acid phosphatases of fungal origin were used and their ability to release orthophosphate from the InsP₆-saturated minerals was evaluated.The phytases showed a high affinity for the mineral surfaces, with a loss of enzyme activity generally being observed over 24 h (up to 95% of the initially added activity). The loss of phytase activity was dependent on the type of mineral, with kaolinite and montmorillonite showing the greatest effect. Retention of enzyme activity was higher with the two oxisol clays, suggesting that the heterogeneous nature of clay surfaces and the presence of endogenous organic matter may limit the inhibition caused by interaction with minerals.In the presence of mineral surfaces saturated with InsP₆, the partitioning of enzyme activity between the solution and the solid phase was shifted more towards the solution phase, presumably due to the mineral surfaces being occupied by the substrate. However, phytases were not able to release any orthophosphate directly from InsP₆-saturated goethite and haematite, and hydrolysed InsP₆ that was desorbed from haematite. Conversely, in the case of kaolinite and of the oxisol clays, where desorption was limited, phytases appeared to be able to hydrolyse a small fraction of the InsP₆ adsorbed on the surfaces. These findings suggest that the bioavailability of P from inositol phosphates is governed to a large extent by the mineral composition of soil and by competitive effects for sorption on reactive surfaces among inositol phosphates and phytases.     

Role of phosphoinositide pathway in the formation of cardiac hypertrophy induced by pressure overload in rats

AIM: To investigate the role of phosphoinositide pathway in the formation of pressure-overload cardiac hypertrophy. METHODS: Cardiac hypertrophy was induced in male Sprague-Dawley rats with coarctation of abdominal aorta, whole heart weight/body weight ratio was tested after 10 or 30 days of operation. Content of Gαq/11 protein in left ventricle was detected by immunoblot analysis and concentration of IP₃ was measured by radioimmunoassay. RESULTS: At 10 and 30 days, whole heart weight/body weight ratio of coarctation aorta (CA) group was higher than that of sham-operated (SO) rats (P＜0.01). Protein Gαq/11 contents were not modified after 10 or 30 days of stenosis (P＞0.05). At 10 days, the level of IP₃ significantly increased in left ventricle of CA rats compared with the control animals (P＜0.05), but there was no difference in IP₃ level between CA and SO group after 30 days of operation. CONCLUSION: Phosphoinositide signaling pathway may play a role in the early stage of cardiac hypererophy induced by pressure overload.     

有机肥料和土壤中的有机磷对水稻的营养效果

本文对三种有机肥料和二种土壤的肌醇六磷酸磷含量和有机磷进行了测定和分组,通过无菌溶液培养,比较了肌醇六磷酸磷与无机磷在等磷量的条件下对水稻的营养效果.结果表明:猪、鸡粪中有机磷的形态主要是以肌醇六磷酸钙镁盐为主,而土壤和牛粪是以肌醇六磷酸铁的形式为主.肌醇六磷酸磷对水稻的营养效果明显优于无机磷.磷的分组结果表明:猪、鸡粪中有机磷以活性和中等活性有机磷为主,而土壤则以稳定性有机磷为主,牛粪介于二者之间.因此,猪、鸡粪中有机磷的有效性高于牛粪,而以土壤中的有机磷为最低.     

2种盐度和3种糖源对凡纳滨对虾生长和糖代谢的影响

为研究肌醇对不同盐度 (4和28) 条件下凡纳滨对虾 (Litopenaeus vannamei) 幼虾生长、血清生化指标和非特异性免疫的影响,选取初始体质量为 (0.75±0.03) g的凡纳滨对虾为研究对象,以添加0、100、200、400、800和1 600 mg∙kg⁻¹肌醇的6种等氮等脂饲料持续投喂10 周。结果表明,高盐度对虾终末体质量、增重率、成活率、特定生长率、蛋白质效率、蛋白质净利用率、总胆固醇含量、酸性磷酸酶、碱性磷酸酶、总超氧化物歧化酶和一氧化氮合酶显著高于低盐度 (P<0.05),饲料系数和水分则相反。饲料系数和总胆固醇含量随饲料中肌醇水平的升高而降低,终末体质量、增重率、成活率、特定生长率、蛋白质效率和蛋白质净利用率则相反,肌醇添加组的肝体比、酸性磷酸酶和碱性磷酸酶活性显著高于对照组 (P<0.05)。综上,饲料中添加肌醇可促进凡纳滨对虾的生长发育,提高其成活率和非特异性免疫力;低盐条件下凡纳滨对虾的生长发育和免疫力受抑制,肌醇水平不低于100 mg∙kg⁻¹能使其生长发育恢复至高盐水平,不低于200 mg∙kg⁻¹可在一定程度上提高其免疫力。     

Quercetin regulates Fas expression and induces apoptosis in hepatocellular carcinoma HepG2 cells

AIM: To investigate the role of 1, 4, 5- trisphosphate inositol (IP3) and Fas gene expression in apoptosis of HepG2 cells induced by quercetin. METHODS: HepG2 cells were treated with quercetin at different concentrations (including 20, 40, 60, 80 μmol/ L) for 72 h and treated with 60 μmol/ L quercetin for 6 h, 12 h, 24 h, 48 h and 72 h. IP3, Fas mRNA, Fas protein and apoptosis rate were assayed by IP3 - ［3H］ Birtrak assay, RT-PCR, Western blotting and flow cytometry, respectively. RESULTS: When HepG2 cells were incubated with different concentrations of quercetin for 72 h, the IP3 content was lower than those in control. Fas mRNA expression, Fas protein expression and the apoptosis rate were higher than those in control. When HepG2 cells were incubated with quercetin for 6 h, 12 h, 24 h, 48 h, 72 h, the IP3 contents were lower than those in control incubated with 60 μmol/L quercetin for 12 h. Fas mRNA expression was higher than that in control incubated with 60 μmol/L quercetin for 12 h . Fas protein expression was higher than that in control. The apoptosis rate was significantly higher than that in control incubated with 60 μmol/L quercetin for 24 h (P<0.01). CONCLUSION: Quercetin induces apoptosis of HepG2 cells by reducing IP3 production and upregulating Fas gene expression.     

外源添加肌醇对大麦发芽过程中一些水解酶活力的影响

为了解肌醇对大麦发芽的影响,研究了浸麦阶段添加肌醇对大麦发芽过程中α-淀粉酶、纤维素酶、蛋白酶、植酸酶、β-葡聚糖酶活力的影响,并对麦芽部分指标进行了比较。结果发现,外源添加肌醇能提高发芽过程中水解酶的活力,α-淀粉酶、纤维素酶、蛋白酶、植酸酶、β-葡聚糖酶活力与对照相比分别提高38.1%、7.0%、12.3%、68.9%、20.5%;浊度降低63.2%,β-葡聚糖降低17.5%,库尔巴哈值得到提高。     

肌醇对团头鲂幼鱼生长、血清生化及组织成分含量的影响

试验以初均重为（3.40±0.07）g的团头鲂幼鱼为研究对象,分别配置含肌醇水平为0 mg/kg、100 mg/kg、200 mg/kg、400 mg/kg、800 mg/kg、1 600 mg/kg的6组等氮等能饲料,每组3个重复,连续投喂90 d后通过测定其生长指标、部分血清生化指标及肝脏和肌肉中的脂肪含量来评价饲料中的肌醇水平对团头鲂幼鱼的影响。结果表明：（1）与对照组相比,400 mg/kg肌醇添加组的末均重（FAW）、增重率（WGR）和特定增长率（SGR）显著增大（P〈0.05）;而饵料系数（FCR）却显著性降低（P〈0.05）;存活率,肝体比（HSI）、脏体比（VR）及肥满度（CF）差异不显著（P〉0.05）;（2）800 mg/kg试验组的血清葡萄糖、胆固醇和低密度脂蛋白显著升高（P〈0.05）;甘油三酯水平显著降低（P〈0.05）;高密度脂蛋白无显著性差异（P〉0.05）; （3）400、800 mg/kg试验组的肝脏和肌肉脂肪含量显著低于对照组（P〈0.05）;而肌肉粗蛋白含量显著升高（P〈0.05）;肌肉中的水分、粗灰分无显著性差异（P〉0.05）。以鱼体特定增长率和饵料系数为评价指标,经折线模型回归分析得到团头鲂幼鱼饲料中肌醇的适宜添加量分别为294.4 mg/kg和284.9 mg/kg。     

Sampling duration and freezing temperature influence the analysed gastric inositol phosphate composition of pigs fed diets with different levels of phytase

This experiment was conducted to determine the effects of time and freezing temperature during sampling on gastric phytate (myo-inositol [MYO] hexakisphosphate [InsP₆]), lower inositol phosphates (InsP_2–5) and MYO concentrations in pigs fed diets containing different levels of phytase. Forty pigs were fed 1 of 4 wheat-barley diets on an ad libitum basis for 28 d. The diets comprised a nutritionally adequate positive control (PC), a similar diet but with Ca and P reduced by 1.6 and 1.24 g/kg, respectively (NC), and the NC supplemented with 500 (NC + 500) or 2,000 (NC + 2000) FTU phytase/kg. At the end of the experiment, chyme were collected from the stomach, thoroughly mixed and 2 subsamples (30 mL) were frozen immediately: one snap-frozen at −79 °C and the other at −20 °C. The remaining chyme were left to sit at room temperature (20 °C) and further subsamples were collected and frozen as above at 5, 10 and 15 min from the point of mixing. There were linear reductions in gastric InsP₆ concentration over time during sampling (P < 0.001), irrespective of diet or freezing temperature. Moreover, InsP₆ concentration was influenced by a diet × freezing temperature interaction (P < 0.05), with less InsP₆ measured in chyme frozen at −20 °C than at −79 °C; however, this difference was greater in the control diets than the phytase supplemented diets. Freezing chyme at −79 °C recovered more ∑InsP_2–5 + MYO than freezing at −20 °C in pigs fed phytase supplemented diets; however, this difference was not apparent in the diets without phytase (diet × freezing temperature, P < 0.01). It can be concluded that significant phytate hydrolysis occurs in the gastric chyme of pigs during sampling and processing, irrespective of supplementary phytase activity. Therefore, to minimise post-slaughter phytate degradation and changes in the gastric inositol phosphate profile, chyme should be snap-frozen immediately after collection.