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1

Potentiometric determination of cysteine with thiol sensitive silver-mercury electrode

100%

Drożdż R., Naskalski J., Ząbek-Adamska A.

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2007

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vol. 54

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issue 1

205-211

EN

A potentiometric procedure for cysteine thiol group concentration monitoring in media generating free radicals was developed using a thiol specific silver-mercury electrode. Electrolytic deposition of mercury on a silver wire and treatment with 20 mM cysteine in 0.5 M NaOH were used to produce the electrode. A silver-chloride electrode in saturated KCl was the reference. A glass capillary with 1 M KNO3 in 1% agarose gel was the liquid junction. The electrode responded to cysteine concentration in the range from 0.01 to 20 mM yielding a perfect linear relationship for the dependence of log [cysteine] versus electrode potential [mV], with b0 (constant) = -373.43 [mV], b1 (slope) = -53.82 and correlation coefficient r2 = 0.97. The electrode potential change per decade of cysteine concentration was 57 mV. The minimal measurable signal response was at a cysteine concentration of 0.01 mM. The signal CV amounted to 4-6% for cysteine concentrations of 0.01 to 0.05 mM and to less than 1% for cysteine concentrations of 0.5 to 20 mM. The response time ranged from about 100 s for cysteine concentrations of 0.01 to 0.1 mM to 30 s at higher cysteine concentrations. The standard curve reproducibility was the best at cysteine concentrations from 0.1 to 20 mM. In a reaction medium containing cysteine and copper(II)-histidine complex ([His-Cu]2+) solution in 55 mM phosphate buffer pH 7.4 the electrode adequately responded to changes in cysteine concentration. Beside cysteine, the silver-mercury electrode responded also to thiol groups of homocysteine and glutathione, however, the Nernst equation slope was about half of that for cysteine.

2

Dynamics of reactive oxygen species generation in the presence of copper(II)-histidine complex and cysteine

100%

Ząbek-Adamska A., Drożdż R., Naskalski J.

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2013

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vol. 60

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issue 4

565-571

EN

Histidine-copper(II) complex (Cu-His2) is a form of bound copper necessary for cellular copper uptake. Due to the high affinity of histidine to copper(II) ions, the binding of copper(II) by histidine is considered a substantial part of plasma antioxidative defense. Also cysteine plays a role in the antioxidative system. However, we show here that in the presence of oxygen the histidine-copper(II) complex plus cysteine produces reactive oxygen species (ROS). Cysteine concentration was assayed using a thiol specific silver-mercury electrode. Hydrogen peroxide was assayed amperometrically using platinum electrode. ROS formation was followed by chemiluminescence of luminol-fluoresceine-enhanced system. Addition of cysteine to Cu-His2 solution at pH 7.4 in the presence of atmospheric oxygen initiates the synthesis of H2O2 and generation of ROS, which manifests as a burst of chemiluminescence. The reaction has two stages; in the first stage, cysteine is utilized for the synthesis of an unstable intermediary product which becomes a substrate for ROS formation. Anaerobic conditions inhibit ROS formation. Increased cysteine concentration enhances the lag phase of the oxidative burst without influencing the amount of ROS. The synthesis of ROS (measured by chemiluminescence) is proportional to the concentration of Cu-His2 employed. ROS production can be repetitively initiated by further additions of cysteine to the reaction medium. The study suggests that Cu-His2 catalyzes cysteine-dependent reduction of oxygen to superoxide employing an intermediary cysteine-copper(I) complex and enabling Fenton reaction with copper and hydrogen peroxide produced as a secondary product. In effect, Cu-His2 with cysteine may be a source of ROS in biological media.

3

Monocyte and neutrophil direct counts correlate with C-reactive protein plasma concentration in patients with acute pancreatitis

88%

Naskalski J., Maziarz B., Kusnierz-Cabala B., Dumnicka P., Panek J.

Open Medicine

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2007

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vol. 2

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issue 1

26-36

EN

Acute pancreatitis (AP) is associated with the intensive inflammatory response in white blood cells (WBC) and C-reactive protein (CRP). This paper presents the relationship between the CRP plasma concentration and the direct counts of peripheral WBC in AP during the initial five days. The study consisted of 56 patients with AP, 36 patients with mild form of AP and 20 patients with severe form of AP. ABX VegaRetic hematological analyzer was used to perform the count of blood cells, and the immunonephelometric method was performed to measure the CRP concentration levels. AP patients presented with WBC count values in the range of 3.2 − 22.4 × 103/µl and CRP concentration levels in the range 3.3 − 599.8 mg/l. The WBC count correlates with CRP levels during the entire observation period. The relationship of CRP and WBC is expressed in the following regression equation: WBC (103/µl) = 3.66 + 1.40 × logeCRP (mg/l). The highest median neutrophil count (8.15 × 103/µl) was observed on the first day. The count decreased to 5.27 × 103/µl on the fifth day. The most substantial finding in this study involved the values found for the monocytes and CRP (r= 0.53; p<0.001). Day two and day three were the highest (r=0.59, p<0.001). On day two, the regression equation for this relationship is: Monocytes (103/µl) = −0.34 + 0.21 × logeCRP(mg/l). The correlation between direct monocyte count and plasma CRP concentration in AP reflect a CRP-dependent stimulation of IL-6 release from activated blood monocytes.

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2 Acta Biochimica Polonica

1 Open Medicine

1 2013

2 2007

3 Naskalski J.

2 Drożdż R.

2 Ząbek-Adamska A.

1 Dumnicka P.

1 Kusnierz-Cabala B.

1 Maziarz B.

1 Panek J.

Potentiometric determination of cysteine with thiol sensitive silver-mercury electrode

Dynamics of reactive oxygen species generation in the presence of copper(II)-histidine complex and cysteine

Monocyte and neutrophil direct counts correlate with C-reactive protein plasma concentration in patients with acute pancreatitis