The role of tungsten in the inhibition of nitrate reductase activity in spinach (spinacea oleracea L.) leaves

1971 ◽  
Vol 44 (3) ◽  
pp. 702-710 ◽  
Author(s):  
B.A. Notton ◽  
E.J. Hewitt
2009 ◽  
Vol 104 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Chong Wei Jin ◽  
Shao Ting Du ◽  
Yong Song Zhang ◽  
Xian Yong Lin ◽  
Cai Xian Tang

1998 ◽  
Vol 14 (2) ◽  
pp. 91-97 ◽  
Author(s):  
Alaa F. Badawi ◽  
Gehan Hosny ◽  
Mohamed El-Hadary ◽  
Mostafa H. Mostafa

It has been suggested that nitrate and nitrite may play a role in the etiology of human oral cancer. We investigated whether salivary nitrate and nitrite and the activity of nitrate reductase (NRase) may affect the risk of oral cancer in Egypt, an area with high levels of environmental nitrosating agents. Levels of salivary nitrite (8.3 ± 1.0 μg/ml) and nitrate (44 ± 3.7 μg/ml) and activity of NRase (74 ± 10 nmol/ml/min) were significantly (P< 0.05) higher in oral cancer patients (n= 42) compared to control Egyptian healthy individuals (n= 40, nitrite = 5.3 ± 0.3 μg/ml, nitrate = 27 ± 1.2 μg/ml, and NRase activity = 46 ± 4 nmol/ml/min). The adjusted odds ratio (OR) and the 95% confidence intervals (C.I.) for risk of oral cancer, categorized by the levels of salivary nitrate and nitrite and NRase activity, showed a higher cancer risk associated with nitrite > 7.5 μg/ml (OR: 3.0, C.I.: 1.0–9.3), nitrite > 40 μg/ml (OR: 4.3, C.I.: 1.4–13.3) and NRase activity > 50 nmol/ml/min (OR: 2.9, C.I.: 1.1–7.4). Our findings suggest that increased consumption of dietary nitrate and nitrite is associated with elevated levels of salivary nitrite. Together with the increased activity of salivary NRase, these observations may explain, at least in part, the role of nitrate and nitrite in the development of oral cancer in individuals from an area with a high burden ofN-nitroso precursors.


1982 ◽  
Vol 68 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Abdelbaset Anwer El-Aaser ◽  
Mahmoud Mohamed El-Merzabani ◽  
Nadia Ahmed Higgy ◽  
Abdel E. El-Habet

A correlation was obtained between a positive nitrite test in urine and the severity of urinary bacterial infection. Bacteria isolated from the urine of bilharzial or bladder cancer patients were found to be rich in nitrate reductase activity. « Escherichia coli » was the most common microorganism isolated from these specimens. Urine and several urinary constituents activate bacterial nitrate reductase. β-Glucuronidase activity in the urine of patients with chronic « Schistosoma haematobium » infection and bladder cancer was measured and shown to be significantly greater than that of urine of normal control subjects. Urinary bacterial infection was shown to be the source of the increased urinary level of enzyme activity at pH 7.0.


Planta ◽  
1978 ◽  
Vol 141 (2) ◽  
pp. 183-189 ◽  
Author(s):  
R. W. Jones ◽  
A. J. Abbott ◽  
E. J. Hewitt ◽  
G. R. Best ◽  
E. F. Watson

1999 ◽  
Vol 79 (3) ◽  
pp. 421-426 ◽  
Author(s):  
Hassan Chadjaâ ◽  
Louis-Philippe Vézina ◽  
André Gosselin

Two cultivars of Lamb's lettuce (Valerianella sp. 'Valgros' et 'Vit') and one cultivar of spinach (Spinacea oleracea L. 'Martine RZ F1') were subjected to three light treatments. Two photoperiods, 12 h and 16 h were compared to natural light between January and April 1994. A photosynthetic flux of 50 µmol m–2 s–1 was provided as supplementary lighting using HPS lamps. The use of artificial lighting significantly increased biomass and nitrate reductase activity, while also reducing nitrate accumulation in leaves. The 16 h-photoperiod increased biomass and reduced nitrates content in leaves more than the 12 h photoperiod. In Lamb's lettuce, Valgos was more productive than Vit but accumulated more nitrates. The use of supplementary lighting gave high yields of lamb's lettuce and spinach in greenhouse under northern climatic conditions. Key words: Lamb's lettuce, spinach, nitrate reductase activity, nitrate, Valerianella sp., Spinacea oleracea L.


Planta ◽  
1993 ◽  
Vol 190 (2) ◽  
pp. 277-283 ◽  
Author(s):  
Alfonso de Cires ◽  
Angel de la Torre ◽  
Begoña Delgado ◽  
Catalina Lara

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