Effect of pH and molar ratio of pollutant to oxidant on a photochemical advanced oxidation process using hypochlorite.

Ultra violet (UV)-photolysis of hydrogen peroxide (H2O2) is a conventional advanced oxidation process (AOP) and is advantageous in its simplicity, although H2O2 is costly. Accordingly, we tried to substitute H2O2 by hypochlorite in the photochemical AOP, and discussed the effect of pH and the molar ratio of a pollutant to hypochlorite on the process using 1,4-dioxane as a model pollutant. The photochemical treatment of hypochlorite solutions at a wavelength of 254 nm under various pH values revealed that the UV-photolysis of hypochlorous acid (HOCl) species mainly contributed to hydroxyl radical (•OH) production. The reaction efficiency, as defined by the molar ratio of removed 1,4-dioxane to consumed hypochlorite, deteriorated under higher pH levels due to the stronger radical scavenging effect of hypochlorite ion (ClO(-)) as compared to that of HOCl. The optimal pH for the UV-photolysis of hypochlorite as an AOP was found to be in the range of 3-6. The reaction efficiency at a high molar ratio of initial 1,4-dioxane to initial hypochlorite exceeded 100%, which was caused by the regeneration of HOCl from photochemically generated chlorine radicals (•Cl). Finally, the overall reaction of the UV-photolysis of HOCl was proposed on the basis of the radical reactions that were related to chlorine species, which suggested that the UV-photolysis of 1 mmol of HOCl stoichiometrically produced 2 mmol of •OH. Since the use of liquid chlorine is more economical than that of H2O2, the substitution of HOCl for H2O2 in the photochemical AOP was concluded to be feasible from the viewpoints of both stoichiometry and chemical costs.

Gender-related differences in target organ damage in untreated patients with essential hypertension.

We examined the gender-related differences in target organ damage in 220 untreated patients with essential hypertension (106 men and 114 women). As the indices of target organ damage, we examined the left ventricular mass index and the intima-media thickness in the carotid and femoral arteries obtained from echocardiography. In a multiple regression model, there was a significant positive correlation between the intima-media thickness and age in both groups. In men, there was a significant positive correlation between the left ventricular mass index and age, as well as the diastolic blood pressure, and body mass index. In women, there was a significant positive correlation between the left ventricular mass index and age, as well as plasma renin activity and smoking. In conclusion, there are gender-related differences in the contributing factors, which relate to left ventricular hypertrophy in patients with essential hypertension.

An in vivo dual-reporter system of cyanobacteria using two railroad-worm luciferases with different color emissions.

In vivo genetic reporter systems using luciferase enzymes enable the real-time monitoring of gene expression in living cells. We have challenged concurrent monitoring of two independent promoter activities within the same cells to precisely compare their characteristics in vivo. In this report, we describe a simple dual-reporter system capable of simultaneously monitoring two promoter activities in living cyanobacterial cells. Two railroad-worm luciferases catalyzing the bioluminescent emissions of different colors served as the dual reporters; each emission was successfully separated by interference filters to estimate the individual bioluminescence signals using photomultiplier tubes. Using this system, we clearly demonstrated the difference in the expression profiles between promoters in the same cells.

Mutations in KaiA, a clock protein, extend the period of circadian rhythm in the cyanobacterium Synechococcus elongatus PCC 7942.

KaiA KaiB and KaiC are essential circadian clock proteins in the unicellular cyanobacterium Synechococcus elongatus PCC 7942. KaiA protein activates transcription of the kaiBC operon, which is believed to be a crucial step in the oscillating feedback loop of cyanobacteria. In this study, approximately approximately 400 mutations were introduced into kaiA by PCR-based mutagenesis, and rhythmic phenotypes of these mutants were studied by a bioluminescence reporter. In contrast to mutations in KaiB or KaiC, the vast majority of KaiA mutations extended the period and only rarely shortened it. The period could be extended to 35 h without lowering the mean or peak levels of kaiBC expression. However, several mutations resulted in low-amplitude oscillations or arrhythmia, which were accompanied by lowered kaiBC transcription. These results imply that the KaiA protein can change the period length of the circadian rhythm directly (through an unknown biochemical mechanism) or indirectly (by lowering kaiBC expression). Specific mutations of KaiA were identified in 34 mutants. While mutations mapped to various locations of the KaiA sequence, two clusters of period-altering mutations were found. This suggested that these regions are important domains of the KaiA protein for defining the period length. On the other hand, different sequences within KaiA to which arrhythmic mutations were mapped are important to enhance kaiBC expression.