Comparison of genotoxic effect between smokeless tobacco (Maras powder) users and cigarette smokers by the alkaline comet assay.

Maras powder (MP) is a kind of smokeless tobacco used in the south-eastern region of Turkey and in several other countries of Middle and Far East. The present study was performed to assess the impacts of MP and cigarette smoking on the possible DNA damaging effect. Alkaline comet assay, which is a reliable and an important tool in human biomonitoring studies in the area of genetic toxicology, was used in peripheral lymphocytes of MP users, cigarette smokers, and non-smokers while their frequencies of total comet scores (TCS) were evaluated. The mean TCS (+/-SD) frequency in the peripheral lymphocytes was 14.4 (+/-10.04) for MP users and 8.26 (+/-5.38), 5.94 (+/-3.87) for cigarette smokers (P < 0.05) and non-smoking control subjects, respectively (P < 0.001). There was no significant effect of daily consumption of MP and the duration of MP usage on comet frequencies. In reply to a wrong belief among MP users ("the use of smokeless tobacco product is substantially less hazardous than cigarettes"), the present study shows that the oral use of smokeless tobacco represents a genotoxic hazard which is even higher than the DNA damage observed in cigarette smokers. Therefore, habitual use of MP should be taken into account and could be considered unsafe, equally harmful, and it should not be viewed as a safe alternative to cigarettes.

The effect of experimental diabetes on the circadian pattern of adenosine deaminase and myeloperoxidase activities in rat liver.

This study investigated time-dependent variations in the activities of adenosine deaminase (ADA), an adenosine-metabolizing enzyme, and myeloperoxidase (MPO), an oxidation reaction-catalyzing enzyme, in control and streptozotocin (STZ)-induced diabetic rat liver. The animals were sacrificed at six different times of day (1, 5, 9, 13, 17 and 21 hours after lights on - HALO). The hepatic activity of ADA did not change depending on the STZ treatment whereas MPO activity was significantly higher in the diabetics than in the controls. Hepatic ADA activity was dependent on the time of sacrifice with the lowest activity at 21 HALO and the highest activity at 5 HALO. Both enzyme activities failed to show any significant interaction between STZ treatment and time of sacrifice, which means that diabetes does not influence the 24 h pattern of these activities. Since MPO, a heme protein localized in the leukocytes, is involved in the killing of microorganisms, increased MPO activity in diabetic rat liver may reflect leukocyte infiltration secondary to diabetes. A reduction in ADA activity during the dark (activity/feeding) period will presumably lead to high concentrations of adenosine in the liver, possibly contributing to changes in some metabolic processes, such as glycogen turnover and oxygen supply.

Protective and therapeutic effects of swimming exercise training on diabetic peripheral neuropathy of streptozotocin-induced diabetic rats.

BACKGROUND: Diabetic peripheral neuropathy (DPN) is a typical complication of diabetes. No definitive treatment and prevention of DPN has been established, and very few data on the role of exercise training on DPN have been reported. AIM OF THE STUDY: The protective and therapeutic effects of aerobic physical activity on the development of DPN in Type 1 were investigated. METHODS: Rats were assigned to 5 groups: C (control), E (exercise), D (diabetic), DEx (exercise after diabetic), ExD (diabetic after exercise); C containing 10 animals and E, D, DEx, ExD containing 15 animals. Diabetes was induced with streptozotocin (STZ) (45 mg/kg, ip). Development of diabetes was confirmed by measuring blood glucose levels 2 days after STZ treatment. Body weights of all the animals were evaluated weekly throughout the experiment. Motor dysfunction defined by a significant increase in compound muscle action potential (CMAP) latency was recorded. The amplitude of CMAP which mainly reflects axonal dysfunction was also measured using standard techniques. Sciatic nerve morphometry and blood glucose levels were analyzed in all the groups. RESULTS: Blood glucose level significantly increased 2 days after STZ injection. All diabetic rats showed decreased body weight compared to control rats. An increase in motor latency of CMAP and a decrease in amplitude of CMAP, indicative of neuropathy, were seen in STZ rats. On the completion of the study (the 56th day post-STZ), histological examination revealed significant myelin loss (thinner myelin) in sciatic nerves of STZ rats. Treatment with swimming exercise had no effect on glycemic control but restored body weight, CMAP amplitude, CMAP latency or motor dysfunction in the diabetic animals. CONCLUSIONS: This study suggests that swimming exercise training has protective and therapeutic effects on DPN of STZ-induced diabetic rats.

The effect of Escherichia coli-derived lipopolysaccharides on plasma levels of malondialdehyde and 3-nitrotyrosine.

The aim of this study was to determine the effect of Escherichia coli (E. coli)-derived lipopolysaccharide on rat plasma low density lipoprotein (LDL), malondialdehyde and 3-nitrotyrosine levels (an indicator of protein nitration). Six hours after intraperitoneal administration of E.coli, plasma LDL was measured electrophoretically and malondialdehyde level was measured by spectrophotometric method. Plasma malondialdehyde was significantly (p<0.001) elevated in E. coli-injected rats (4.97 +/- 1.33; n=10) in comparison to control animals (1.83 +/- 0.5; n=10). In addition, plasma 3-nitrotyrosine level, determined by reverse-phase HPLC, was also increased in the infected group (2.84 +/- 1.17 to 0.22 +/- 0.13; n=10). This increase was statistically significant (p<0.001). An increased level of oxidation of lipids and 3-nitrotyrosine was observed as a result of free radical-mediated damage in plasma. In conclusion, asymptomatic infections may increase the risk of atherosclerosis by inducing free radical formation and a consequent increase in the oxidation of LDL.

Pulmonary function tests, aerobic capacity, respiratory muscle strength and endurance of patients with rheumatoid arthritis.

Patients with rheumatoid arthritis (RA) show lower cardiorespiratory fitness than normal subjects. This study was planned to investigate the pulmonary function tests (PFT), respiratory muscle strength and endurance, and aerobic capacity of patients with RA, as well as the relationship of these parameters to clinical and functional status. Twenty-five RA patients aged 25-71 (48.52 +/- 14.09) and 21 control subjects aged 25-66 (45.67 +/- 13.27) participated in the study. PFT, maximum volunteer ventilation, maximum inspiratory and maximum expiratory pressures and cardiorespiratory exercise tests were carried out in all subjects to evaluate the respiratory involvement, inspiratory and expiratory muscle strength and endurance, and aerobic capacity. Patients' duration of disease, smoking and alcohol habits, duration of morning stiffness, visual analogue scale scores, ARA functional classifications and Ritchie articular indexes were recorded. All the patients and control subjects were non-exercising individuals. As a result, we found that RA patients have normal PFT but reduced respiratory muscle strength and endurance, and also reduced aerobic capacity compared to controls. According to this result, respiratory and aerobic exercises may be recommended to improve respiratory muscle strength and endurance and aerobic capacity in these patients.

The effects of peroxynitrite on erythrocytes.

Endotoxin-induced peroxynitrite formation has been demonstrated in plasma. The aim of this study is to evaluate whether this has an effect on erythrocytes. For this purpose erythrocyte 3-nitrotyrosine (3-NT) level, Na+-K+ ATPase and glutathione peroxidase activities were measured both in vivo and in vitro. In vivo peroxynitrite formation was induced in rats by intraperitoneal Escherichia coli (E.coli) injection. Erythrocytes were directly incubated with peroxynitrite in the in vitro experiment. 3-NT levels were measured by reverse-phase HPLC, glutathione peroxidase, and Na+-K+ ATPase activities were measured by spectrophotometric techniques. There was a marked increase in the 3-NT levels in both experiments. However, glutathione peroxidase activity was significantly increased in in vivo experiments, while decreasing in in vitro conditions. Although Na+-K+ ATPase activities were significantly reduced by peroxynitrite in vitro, Na+-K+ ATPase activities were similar in control and E.coli-injected rat erythrocytes. Although nitrating effect of peroxynitrite does not seem to be preventable by endogenous antioxidants, this effect of peroxynitrite may not endanger erythrocytes if the oxidative damage of peroxynitrite is prevented.