The parkin protein functions as a RING-type ubiquitin protein ligase. Considering the possibility that impaired ubiquitin-proteosomal system activity may impair antioxidant defenses and enhance oxidative stress, we have investigated the activity of mitochondrial respiratory enzymes in patients with parkin gene mutations. A significant decrease in the leukocyte complex I activity was found both in patients with parkin mutations (62.5%) and idiopathic PD (64.5%) compared with age-matched controls (P < 0.001). Complex IV activity was also decreased significantly in idiopathic PD patients (60%), but no difference was detected between controls and patients with parkin mutations.
AbShCtThe kinetics and equilibria of S-nitrosothiol-thiol (SNO-SH) exchange reactions were determined using differential optical absorption. At pH 7.4and 37'C, k2 values ranged from 0.9 M-i . s-' for the reaction between S-nitroso-glutathione (GSNO) and N-acetyl-penicillamine, and up to 279 M-' . se1 for the exchange between S-nitroso-penicillamine (penSNO) and GSH. SNO-SH exchange involving GSIWGSNO and cysteine/cySNO was relatively rapid, k, approx. 80 M-' . s-' with an equilibrium constant slightly in favour of GSNO. GSNO was strongly favoured in equilibrium with penSNO, k, 0.0039. In the case of SNG-SH exchange between S-nitroso human serum albumin (albSN0) and GSH or cysteine k2 values were 3.2 and 9.1 M-i . s-l, respectively. The results show that the initial rate of SNO-SH exchange between physiological albSN0 (7 @I) and venous plasma levels of GSH and cysteine is very slow, < l%/min. On the other hand, if a nitrosothiol such as cySN0 were to enter a cell, it would be rapidly converted to GSNO (43%/s).
A possible link between superoxide dismutase activity and malondialdehyde level with the clinical manifestations of rosacea was investigated. We found differences in superoxide dismutase activities between mild rosacea (stages I and II) and severe involvement (stage III) groups, as well as between disease and control groups that were statistically significant (P < 0.05). In the mild involvement group (stages I and II), the superoxide dismutase activity was higher than in the control group (P < 0.05), while the malondialdehyde levels did not differ from the control. In the severe involvement group (stage III), the superoxide dismutase activity was lower than in the control group (P < 0.05), and this was coupled to a raised level of malondialdehyde (P < 0.05). These findings clearly show that in the mild involvement phase of rosacea patients, superoxide dismutase activity was stimulated to protect the skin against reactive oxygen species so that the malondialdehyde levels were maintained. In contrast, in more severe disease, due to a decrease in the capacity of the antioxidant defence system, the malondialdehyde levels were increased. These findings support the 'antioxidant system defect hypothesis' in rosacea patients.
The present study was undertaken in order to determine the possible alterations in whole saliva and the periodontal status in patients with diabetes mellitus (DM), and was conducted on 17 patients with DM and 17 systemically and periodontally healthy subjects. When the subjects were evaluated clinically, significantly increased probing depths were noticed in the DM group when compared with the healthy subjects. In whole saliva samples, sodium, potassium, total protein, amylase, thiocyanate, and secretory IgA levels were determined in both groups. Difference between the two groups regarding the mean salivary potassium levels were found to be statistically significant since the mean salivary potassium levels in the DM and the control groups were 2.470 +/- 9.04 mmol/L and 14.30 +/- 8.88 mmol/L, respectively. The mean salivary total protein, amylase and secretory IgA levels in the DM group were 2.41 +/- 1.0 mg/mL, 124.2 +/- 79.7 U/mL and 6.86 +/- 3.50 mg/L, all being significantly higher than the control group. However, no significant differences could be shown for the salivary sodium and thiocyanate levels. Nor was there any difference between non-insulin dependent diabetes mellitus (NIDDM) and insulin-dependent diabetes mellitus (IDDM). The findings of the present study suggest that, besides the clinical examinations, the determination of the possible alterations in the composition of whole saliva might also be helpful in understanding the increased severity of periodontal disease in diabetic patients.
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