Collagen synthesis, nitric oxide and asymmetric dimethylarginine in diabetic subjects undergoing hyperbaric oxygen therapy.

The main pathological condition in patients with impaired wound healing is diabetes mellitus. These patients have significantly low circulating nitric oxide (NO) levels because the stimulatory action of insulin on NO synthesis is absent. Additionally, asymmetric dimethylarginine (ADMA), an inhibitor of NO synthase, is increased owing to the generation of oxidative stress. NO was thought to contribute to wound healing. Hyperbaric oxygen (HBO) treatment is generally used in order to accelerate the healing of wounds. The aim of this study was to determine the changes in plasma procollagen type I and III N-terminal peptides (PINP and PIIINP), total nitrite/nitrate (NO(x)) and ADMA levels; and to evaluate their relation to healing during the HBO treatment of foot ulcers. Data obtained from 18 diabetic patients before and after the HBO therapy were compared statistically by the Wilcoxon test. NO(x) was increased in 11 and ADMA was decreased in 12 patients following HBO treatment. Both PINP (32.6 +/- 29.4 microg/l vs 44.3 +/- 33.4 microg/l) and PIIINP (6.97 +/- 3.01 microg/l vs 7.92 +/- 2.49 microg/l) were significantly increased (p < 0.05). Progressive reductions were observed in wound areas, as assessed by the digital wound imaging. In 12 patients, wounds healed by 50% or higher; whereas only two subjects had minimal improvements (15% or less healing). The duration of diabetes correlated negatively with wound healing (r = -498, p < 0.05). This study suggests that increased collagen synthesis is associated with wound healing during hyperbaric oxygen therapy. Nitric oxide generation may also contribute to the healing process.

Early and late effects of hyperbaric oxygen treatment on oxidative stress parameters in diabetic patients.

Exposure to hyperbaric oxygen leads to increased amount of reactive oxygen species (ROS) that are derived from various sources. After the discovery that ROS can function as signaling molecules, the idea of ROS being hazardous to biological tissues has been challenged. The aim of this study was to examine the changes in oxidative stress parameters in diabetics undergoing hyperbaric oxygen therapy (HBOT) due to foot ulcers. Twenty patients, who received HBOT for diabetic foot ulcers, were included in the study. Blood samples were taken before HBOT and 30 min after exit from the chamber, on the day of the first and the fifteenth HBOT sessions. They were used for the determinations of malondialdehyde (MDA), 8-isoprostane and advanced oxidation protein products (AOPPs). 8-Isoprostane and AOPP levels were not altered significantly after the first HBOT session, while both were increased on the fifteenth day (p<0.05). MDA was significantly increased only after the first HBOT session, and remained unchanged on the fifteenth day (within-day variations). Plasma AOPP levels were lowered significantly after fifteen consecutive HBOT sessions (between-day variations). Decreased AOPP levels suggest that increased oxygenation of tissues due to HBO therapy may activate some endogenous factors that prevent hazardous effects of the disease itself.

Circulating ghrelin levels in obese women: a possible association with hypertension.

OBJECTIVE: The orexigenic hormone ghrelin induces weight gain by stimulating food intake. Ghrelin has been shown to modulate sympathetic activity, to exert vasodilative effects and to counterreact with leptin on both food intake and blood pressure. Of these two hormones, ghrelin levels are decreased in obesity, whereas leptin levels are increased. In this cross-sectional study, differences in serum ghrelin and leptin levels were examined in normotensive and hypertensive obese women. MATERIAL AND METHODS: Sixty-one normotensive and hypertensive women were classified according to the body mass indices as follows: (a) 18 healthy subjects with BMI 21.5-27.5 kg/m(2); (b) 22 normotensive subjects with BMI 30-47 kg/m(2); (c) 21 hypertensive obese subjects (BMI 30-48 kg/m(2)) with systolic blood pressure > or =140 mmHg or diastolic blood pressure > or =90 mmHg. Anthropometric measurements including height, weight, BMI, waist and hip circumferences and blood pressure were recorded. The levels of ghrelin and leptin were determined in sera using the commercial ELISA kits. RESULTS: In normotensive obese subjects, ghrelin levels were significantly lower than in controls (0.21+/-0.13 vs 0.60+/-0.3 ng/mL), whereas hypertensive obese women had elevated ghrelin levels (0.64+/-0.36 ng/mL). Ghrelin concentration was decreased despite the presence of hypertension in the patients who had BMIs above 35 kg/m(2). Leptin levels were significantly higher in both normotensive and hypertensive obese groups (19.54+/-11.19 and 21.61+/-12.7 ng/mL, respectively) than in controls (7.61+/-3.3 ng/mL), and were not affected by the presence of hypertension in obese subjects. CONCLUSION: Ghrelin was positively associated with hypertension in obese women and this association was inversely influenced by the increase of BMI.

Advanced oxidation protein products in obese women: its relation to insulin resistance and resistin.

Obesity is a major risk factor for insulin resistance and type 2 diabetes mellitus (T2DM). Resistin, an adipocyte-secreted hormone, is thought to take a part in the development of insulin resistance and T2DM. The aim of this study was to characterise the changes in circulating levels of resistin and proinflammatory cytokines tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6 in diabetic and prediabetic obese patients and to explore their relationship to insulin resistance. Attempts were also made to see whether resistin levels are related to the degree of oxidative stress, as determined by the measurement of advanced oxidation protein products (AOPPs). The study groups consisted of obese diabetic (BMI: 30-42 kg/m(2), n=28) and prediabetic (BMI: 29-41 kg/m(2), n=23) women. Fourteen healthy women, with BMI in the range 21.5-25.5 kg/m(2), were taken as controls. Serum levels of TNF-a, IL-6, resistin, glucose, insulin and AOPPs were measured. Insulin resistance was calculated by the homeostasis model assessment (HOMA-IR). Diabetic and prediabetic obese patients had increases in serum resistin and TNF-alpha levels (P<0.01 and P<0.001, respectively). IL-6 levels in diabetic patients were significantly higher than in prediabetics (P<0.05). AOPP levels were also significantly higher in diabetics than prediabetics and controls (P<0.05 and P<0.001, respectively); and positively correlated with blood glucose. Insulin was significantly associated with circulating resistin and TNF-alpha. The development of insulin resistance may contribute to the elevation of circulating resistin or vice versa. Determination of AOPPs may be helpful for monitoring the impaired glucose metabolism in obesity.

Cystatin-C and creatinine as indices of glomerular filtration rate in the immediate follow-up of renal transplant patients.

Serum cystatin-C (cys-C), creatinine (Cr), C-reactive protein (CRP) and amyloid A have been shown to provide useful information for renal function following transplantation. In this study, we wanted to evaluate the impact of these parameters as markers of the glomerular filtration rate (GFR) on the third and seventh days of the post-transplantation period. Cys-C was determined by the particle-enhanced immunoturbidimetric assay, and serum amyloid A (SAA) by the sandwich-enzyme immunoassay kit. Cr and CRP concentrations were measured by the Cobas Integra 400 autoanalyser. The patients (n=35) were followed with daily repetitive measurements of serum Cr and urine output per hour, and with Doppler ultrasonography against the risk of rejection. Statistical evaluations were made using the ANOVA and Pearson's test. Serum cys-C and Cr levels on both the 3rd and 7th days after transplantation were lower than those of pretransplantation values (P<0.001). The Cr/cys-C ratio was decreased on the 3rd day of the post-transplantation period, and kept declining on the 7th day. This ratio was high only in the patient with an acute rejection episode. None of the patients with high pretransplant CRP levels had a rejection episode during a six-month follow-up. SAA concentrations were found to be higher than the pretransplant values in the early post-transplant period. Cys-C had good sensitivity to estimate the renal function in the very early period of transplantation, but its value as a marker of GFR was decreased at the end of first week. As none of the 34 patients had a rejection episode, the observed rise in SAA and CRP levels is not specific to rejection.

Coadministration of melatonin and estradiol in rats: effects on oxidant status.

This study was designed to investigate the effects of melatonin and estradiol (E2) on lipid peroxidation and antioxidant defense enzymes in blood and liver tissue when administered in vivo. Wistar albino rats were divided into three experimental groups and treated with either estradiol (25 mg/kg bw, s.c.), melatonin (i. p.), or melatonin plus E2, whereas control animals had diluent injections only. Melatonin was given 10 mg/kg bw x 2 intraperitoneally 30 min before and 60 min after E2 treatment to the melatonin plus E2 group. Animals were sacrificed three hours after the estradiol injection, and their blood and liver tissues were prepared for biochemical analyses. Tissue malondialdehyde (MDA) levels and antioxidant enzyme activities--superoxide dismutase (SOD) and glutathione peroxidase (GPx)--were determined in the postmitochondrial fraction, and the results were compared. Estradiol injection caused significant increases in both MDA levels and GPx activity in liver. When melatonin was administered in combination with E2, the effect of estradiol on MDA levels was abolished. A significant decrement in SOD activity occurred in melatonin-treated animals. GPx activity in the blood of E2 plus melatonin-injected animals was significantly higher than those in control animals. Melatonin-treated animals exhibited relatively lower levels of SOD activity than those from the control and E2 plus melatonin groups. This indicates that estradiol could exert oxidant action resulting in an increment in tissue malondialdehyde levels. Enhanced activity of GPx in both liver and blood following melatonin injection may indicate the contribution of this neurohormone on the antioxidant defense.

The effects of acute melatonin and ethanol treatment on antioxidant enzyme activities in rat testes.

The pineal hormone melatonin (N -acetyl, 5-methoxytryptamine) was recently accepted to act as an antioxidant under both in vivo and in vitro conditions. In this study, we examined the possible preventive effect of melatonin on ethanol-induced lipid peroxidation in rat testes. Thirty-seven male Wistar albino rats, 5.5--6 months old, were randomly divided into four groups (9--10 animals in each). The first group (control animals) received 4% ethanol at similar intervals to the experimental groups to equalize the stress effect. The second group received only melatonin i.p. 7 mg kg(-1)bw three times over 1.5 h intervals. The third group received only 30% alcohol 3 g kg(-1)bw twice daily. The fourth group were treated with melatonin and ethanol according to the above protocol, melatonin injections preceding ethanol treatments. The product of lipid peroxidation, malondialdehyde (MDA) and antioxidant enzymes, superoxide dismutase (Cu--Zn SOD), glutathione peroxidase (GPx) and catalase (CAT) were measured in the post-mitochondrial fraction of the testes. MDA levels were significantly increased due to acute ethanol intoxication. GPx activity was higher in the three experimental groups than the control levels. The activity of CAT was increased significantly in the melatonin plus ethanol-treated group but the other groups appeared not to be influenced by acute ethanol treatment. Cu--Zn SOD activity remained unaltered. These results suggest that antioxidants may be a protective agent for the testicular injury caused by ethanol consumption.

Acute effects of estradiol and of diethylstilbestrol: pro- or antioxidant potential?

This study was aimed to examine the effects of a single high dose of natural and synthetic estrogens on the antioxidant defense enzymes in liver and blood. Female Wistar albino rats, four to six months old, were divided into three groups, and received either i.p. injections of diethylstilbestrol (DES ; 150 mg kg(-1) b.w.) or s.c. injections of estradiol (E2; 25 mg kg(-1) b.w.), and the third group (control) was injected the solvent. Animals were killed under light ether anesthesia three hours after injection. Cu-Zn superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (Cat) enzyme activities and fluorometric malondialdehyde (MDA) determination were performed in liver tissue homogenates and in blood. Acute estradiol injection caused a significant increase in both MDA levels and GPx activity in liver tissue when compared to the controls, (p <0.05 and p <0.02; respectively). Changes in both enzyme activities and MDA concentration were unremarkable following acute DES injection. In blood, only Cu-Zn SOD activity was significantly altered in blood following E2 injection. Although the significance of alteration in GPx activity remains unclear, it is most likely related to enhanced generation of lipoperoxides. A significant increase in MDA concentrations in liver tissue is indicative of pro-oxidative damage rather than an antioxidant action by E2.

The effect of melatonin administration on ethanol-induced lipid peroxidation in rats.

This study was carried out in order to determine the role of melatonin in preventing lipid peroxidation due to acute ethanol intoxication. Male Wistar Albino rats, 2.5-3 months old, were divided into two groups. Melatonin (in 1% ethanol, 2 mg kg-1 body weight) was given intraperitoneally (i.p.) for 21 days to experimental rats whereas controls received 1% ethanol only. On day 21, 6 g kg-1 body weight ethanol was injected to half of the animals in each group and the remainder were kept as corresponding controls. Animals were killed 5 h after ethanol injection. Malondialdehyde (MDA), reduced glutathione (GSH) and the antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase and catalase) were determined in liver tissue homogenates. MDA levels were increased whereas GSH levels tend to decrease following alcohol injection. Melatonin administration prior to ethanol did not alter MDA and GSH levels of tissue and among antioxidant defence enzymes studied, only CuZn-SOD was found to be increased in animals that received melatonin + ethanol. According to the findings of this study, melatonin did not appear to have any direct effect on alcohol-induced lipid peroxidation.

The effects of fluorides and/or trace elements on the solubilities of enamel and cementum.

The purpose of this study is to determine the effects of fluorides and trace elements applied alone or in combination at different concentrations on the solubilities of enamel and cementum surfaces of the same teeth. The study has been performed on enamel and cementum surfaces of the impacted third molars extracted by surgical operation. Aqueous solutions of sodium fluoride, aluminum potassium phosphate, strontium chloride and titanium tetrachloride at different concentrations were applied to the surfaces. The solubilities of enamel and cementum and the depth of etchings have been calculated by means of the inorganic phosphorus in these etching solutions. According to the results, higher concentrations of fluoride and lower concentrations of strontium and titanium led to a significant reduction into solubilities of enamel and cementum. As certain combined applications of fluorides and trace elements decreased both of the enamel and cementum solubilities, it may be assumed that if such a treatment is beneficial during the adolescence of an individual, it may also be used when he is older.