Antioxidant role of heme oxygenase-1 in prehepatic portal hypertensive rats

AIM： To study the effect of bilirubin on the oxidative liver status and the activity and expression of heine oxygenase-1 （HO-1） in rat liver injury induced by prehepatic portal hypertension. METHODS： Wistar male rats, weighing 200-250 g, were divided at random into two groups： one group with prehepatic portal hypertension （PH） induced by regulated prehepatic portal vein ligation （PPVL） and the other group corresponded to sham operated rats. Portal pressure, oxidative stress parameters, antioxidant enzymes, HO-1 activity and expression and hepatic sinusoidal vasodilatation were measured. RESULTS： In PPVL rats oxidative stress was evidenced by a marked increase in thiobarbituric acid reactive substances （TBARS） content and a decrease in reduced glutathione （GSH） levels. The activities of liver antioxidant enzymes, superoxide dismutase （SOD）, catalase （CAT） and glutathione peroxidase （GSH-Px） were also diminished while activity and expression of HO-1 were enhanced. Administration of bilirubin （5μmol/kg body weight） 24 h before the end of the experiment entirely prevented all these effects. Pretreatment with Sn-protoporphyrin IX （Sn-PPIX） （100 μg/kg body weight, i.p.）, a potent inhibitor of HO, completely abolished the oxidative stress and provoked a slight decrease in liver GSH levels as well as an increase in lipid peroxidation. Besides, carbon monoxide, another heme catabolic product, induced a significant increase in sinusoidal hepatic areas in PPVL group. Pretreatment of PPVL rats with Sn-PPIX totally prevented this effect CONCLUSION： These results suggest a beneficial role of HO-1 overexpression in prehepatic portal hypertensive rats.

Changes in Texture, Structure and Pectin of Peach during Pressurization, Heating or Processing of High-pressure-induced and Heat-induced Jam

The objectives of this study are to research the relationship between pectin and the softening of peach by soaking in citric acid solutions for 24 h at 35 ℃, pressurizing for 30 rain at 500 MPa or heating for 10 min. Also, comparing high-pressure-induced jam （HP-jam） and heat-induced jam （H-jam） were evaluated. It was found that firmness of the peach decreased greatly when soaked at pH 2.0 〉 heated 〉 soaked at pH 2.2 or 2.5 〉 pressurized, respectively. About 88% of the peach pectin was water-soluble-pectin and high-methoxyl pectin, while low-methoxyl pectin was slight. During pressurization, the pectin did not change. However, pectin degraded through hydrolysis during heating; consequently, the middle lamella separated. Also, eight kinds of peach jam （65% sugar, pH 2.0 or pH 2.2, and 50% or 60% sugar, pH 2.5） were compared. Both color and flavor of HP-jam were better than H-jam. As the pH values were lower, L-, a-, b-values of jam became higher, and the jam became pinker. Raw peach contained about 0.3%-0.4% pectin, therefore, an addition of 0.6% pectin was needed for both HP- and H-jams. However, there was no great difference in rheology or sensory evaluation between HP- and H-jams.

Promotion effect of KOH on preparation of dissolved Fe(Ⅵ)

In order to improve the yield and stability of ferrate in solution, dissolved Fe(Ⅵ) prepared with NaOH and KOH respectively was compared in this study. The results showed that KOH is more suitable than NaOH for the preparation of dissolved Fe(Ⅵ) at temperature over 50 ℃. It is found that the dissolved Fe(Ⅵ) prepared with KOH increases quickly at first, and then slowly with the increasing concentrations of OH-and ClO-, while it increases rapidly at first and then decreases rapidly with the increasing dosage of Fe(NO3)3·9H2O. These results are different from that prepared with NaOH. It can be explained that solid K2FeO4 salts can be formed in KOH solution, and it will lower the Fe(Ⅵ) concentration, counteract the decomposition of Fe(Ⅵ), and improve the yield of Fe(Ⅵ). The maximum ferrate concentration is 0.163 mol/L obtained by 100 g/L Fe(NO3)3·9H2O and 6.16 mol/L KOH at 65 ℃. The stability of Fe(VI) is greatly improved due to the hypochlorite existed in the dissolved ferrate, and only 24% Fe(Ⅵ) has been decomposed after 16 d for 1 mmol/L Fe(Ⅵ) at 25 ℃.

The preparation of rat heme oxygenase 1 mutant to reduce the level of bilirubin

Objective To prepare rat heme oxygenase 1 (HO 1) mutants and to determine the activity and inhibition of this mutated enzyme Methods pcDNA3HO1 containing truncated native rat HO 1 cDNA and pcDNA3HO1Δ25 carrying mutated rat HO 1 cDNA (His25Ala) were constructed, respectively COS 1 cells transfected with pcDNA3HO1 and pcDNA3HO1Δ25 were collected and their activities were analyzed Results Native rat HO 1 was highly expressed in transfected cells and its activity was 13?688-15?600?U/mg protein per hour However, the enzyme activity of mutated HO 1 declined and the value was 1948-2160?U/mg protein per hour When an equal amount of mutant was added to the enzyme reaction system, the level of bilirubin decreased by 42% Conclusion The His25Ala mutant reduced the formation of bilirubin, suggesting that the mutant could competely bind the heme with native enzyme