Biltan Ersöz

MAO inhibitors and oxidant stress in aging brain tissue

The process of aging presents itself with various alterations in physiological events. Among many theories, the free radical (FR) theory of aging which reflects the FR damage to cellular components is accepted as one of the most important theories. Recently, the increases in catecholamine metabolism in aging have also attracted attention, and monoamine oxidase (MAO), a key enzyme in this process has been extensively studied. The aim of this study was to assess the role of FR species via MAO, a possible source of FRs, in physiological aging by determining the lipid peroxidation products (LPP) (malondialdehyde, diene conjugates) and antioxidant enzyme levels (superoxide dismutase (SOD) and catalase (CAT) in young (3 months old, n=10) and aging (16-18 months old, n=10) rat brain tissues of Swiss male albino rats. In the second part of the study, the same parameters were determined after the acute administration of MAO inhibitors (deprenyl and pargyline, 25 mg/kg i.p.) to investigate whether these agents have any beneficial effects in reducing oxidant stress via inhibition of MAO. In old rat brains, MAO activities showed a significant increase (P=0.000) in addition to an insignificant increase in LPP, while SOD (P=0.007) and CAT activities showed a decrease with advancing age. After the acute administration of both deprenyl and pargyline, a significant decrease in the MAO activities of both young (P=0.0002 for each) and aging rats (P=0.0002 for deprenyl and P=0.0001 for pargyline) were observed. It was noted that deprenyl causes a significant increase in CAT activity (P<0.05) but a significant decrease in SOD activity (P<0.05) in young rats, while it causes only a significant increase in SOD activity in aging rats (P<0.05). Both deprenyl and pargyline cause a significant decrease in conjugated diene levels of aging rats (P<0.05). These results confirm the role of catecholamine oxidation and MAO activity as one of the causative factors in increased oxidant stress during aging. By reducing the oxidant stress observed in aging brain, MAO inhibitors, especially deprenyl, may contribute to the control of the aging process.

Antioxidant enzymes and paraoxonase show a co-activity in preserving low-density lipoprotein from oxidation.

Abstract Oxidative modification of low-density lipoprotein in the artery wall plays a crucial role in the development of atherosclerosis. This physiopathological mechanism is clearly inhibited by high-density lipoprotein possibly via paraoxonase enzyme activity, present in high-density lipoprotein. In this study we determined the in vitro susceptibility of low-density lipoprotein to oxidation and the effect of various factors, such as paraoxonase phenotypes, on this process. Low-density lipoprotein from healthy volunteers (n=66) was isolated using the precipitant reagent and the oxidation was evaluated by measuring the malonyl dialdehyde and diene levels. Low-density lipoprotein cholesterol and phospholipid, vitamin E, serum cholesterol, high-density lipoprotein and low-density lipoprotein cholesterol levels, and erythrocyte antioxidant enzymes were also determined. There was no difference among the parameters with regard to gender. Low-density lipoprotein samples obtained from subjects with the AA allele were more prone to oxidation, as observed by their higher stimulated conjugated diene (P=0.041) and thiobarbituric acid-related substance (P=0.042) levels, than samples from subjects with AB or BB alleles. The subjects with the BB allele had higher superoxide dismutase (P=0.021) and catalase (insignificant increase) activities, while their conjugated diene (P=0.000) levels were lower. In conclusion, our results revealed that the high low-density lipoprotein oxidation is related to the high low-density lipoprotein cholesterol content and low phospholipid content. The present study demonstrated an increase in superoxide dismutase and catalase activities, asl well as PON1 activities, in subjects with the BB allele. Since these enzymes all show activity against low-density lipoprotein oxidation, we propose that future investigations on atherosclerotic processes should address PON1 polymorphism as well as PON1 and other antioxidant enzymes.

The Effects of N-Acetylcysteine on Oxidative Stress in Organophosphate Poisoning Model

Organophosphate compounds act by irreversible inhibition of cholinesterase. In addition to their muscarinic, nicotinic, and central nervous system effects, some organophosphate insecticides cause oxidative stress by increasing lipid peroxidation in erythrocytes and by increasing levels of the enzymes Superoxide dismutase and catalase. In this study, the effects of an antioxidant,N-acetylcysteine (NAC), in organophosphate poisoning were investigated. After obtaining Animal Ethics Committee approval, 16 male Wistar rats were divided into 2 groups. Following anesthesia, rats were tracheostomized and mechanically ventilated. Invasive hemodynamic monitoring was begun and all rats were injected with 70 mg/kg of dichlorvos (DDVP) intraperitoneally. The rats in group 1 received placebo intravenous 0.9% NaCl and the rats in group 2 received 150 mg/kg intravenous NAC. Blood samples were obtained before injection of DDVP and 60 minutes after injection to determine levels of malondialdehyde, superoxide dismutase, and catalase. Hemodynamic data and biochemistry test results were compared by analysis of variance and Wilcoxon test.P< .05 was regarded as statistically significant. Superoxide dismutase and malondialdehyde levels were significantly increased in group 1 while no difference was observed in group 2. It was concluded that organophosphate compounds might cause oxidative stress by interfering with antioxidant defense mechanisms in erythrocytes and that NAC might prevent increased lipid peroxidation. In addition to classic treatments, drugs with antioxidant effects might therefore be promising in the treatment of organophosphate poisoning.

Alterations in l -arginine and inflammatory markers in type 2 diabetic patients with and without microalbuminuria

Low-grade inflammation is closely involved in the pathogenesis of type 2 diabetes and associated micro- and macrovascular complications. The nitric oxide (NO) precursor l-arginine, is relevant to diverse pathological conditions including type 2 diabetes and its complications. High sensitive-CRP (hs-CRP), neopterin and arginine levels were measured in 46 normoalbuminuric, 45 microalbuminuric type 2 diabetics and in 32 healthy controls in order to assess the relationship between markers of inflammation and l-arginine. Hs-CRP concentrations were higher in microalbuminuric diabetic patients compared to normoalbuminuric patients and controls. Diabetics had higher serum and urine neopterin levels than controls. Urine neopterin and l-arginine levels differed significantly among diabetic patients with and without microalbuminuria. There were significant positive correlations between hs-CRP and BMI in healthy controls and diabetics with and without microalbuminuria. In microalbuminuric diabetics, hs-CRP correlated with microalbuminuria (MAU). Significant predictors for the development of microalbuminuria were higher postprandial glucose levels, lower creatinine clearance and lower serum l-arginine levels. Assessment of early markers of inflammation and endothelial function, such as neopterin and NO precursor l-arginine, may help to predict incipient nephropathy more accurately in type 2 diabetic patients.

Trace elements analysis of ascitic fluid in benign and malignant diseases

OBJECTIVES To evaluate differences in ascitic fluid trace element concentrations which might be useful in discrimination between benign and malignant ascites. DESIGN AND METHODS The concentrations of copper, zinc, magnesium and iron in ascitic fluid and venous blood in 17 patients were investigated. The relationship between these trace elements and type of disease were examined. Investigations were carried out in a group of 5 males and 5 females aged 54 to 77 yr who had cirrhosis ascites and in a group of 7 females aged 41 to 76 yr with ascites due to gynecologic neoplasms. RESULTS The mean ascitic fluid and serum concentrations of copper were significantly higher in neoplastic diseases compared to benign disease states (118,43 vs. 97,50, 91,14 vs. 26.90) (p < 0,05 and p < 0,01 respectively). The zinc levels in ascitic fluid and serum were significantly different between the groups (p < 0,01). Neoplastic patients had significantly higher ascitic fluid magnesium levels than the benign disease group (2,17 vs. 1,55, p < 0,001). The serum levels of iron were significantly lower in the neoplastic diseases group (92, 28 vs. 255, p < 0, 01). In benign diseases the concentration of zinc in ascitic fluid correlated positively with ascitic fluid copper concentrations. The concentrations of zinc and iron in malignant ascites correlate positively with the magnesium concentrations. Statistically significant negative correlations were found between ascites zinc and magnesium and magnesium and copper in cirrhotic patients and magnesium and copper in malignant diseases. CONCLUSIONS The results showed that zinc, magnesium and iron levels were significantly different between cirrhotic and neoplastic illness. Analysis of serum and ascitic fluid trace element composition may be helpful in identifying and distinguishing the malignant and nonmalignant ascites and provides useful information on processes regulating passage of blood components into the peritoneal cavity.

Age and sex related alterations in serum and platelet monoamine oxidase.

The process of aging presents itself with various alterations in physiological events. Although the turnover of catecholamines increases with aging, there is a lack of response to catecholamines in target tissues. One of the key enzymes in catecholamine metabolism is monoamine oxidase. It has been suggested that tissue and serum monoamine oxidase activities show pathological alterations in various diseases while physiological fluctuations can also be detected in normals. The aim of this study is to determine the sex and age related changes of platelet and serum monoamine oxidase in healthy volunteers. In this study, 75 healthy volunteers of different ages (21-80 a) and sexes (40 females, 35 males) were included. Serum and platelet monoamine oxidase determinations were performed spectrophotofluorometrically by Tufvessons (Scand J Clin Lab Invest 1970; 26:151-4) and Kramls (Biochem Pharmacol 1965; 14:1684-6) modified methods, respectively. While there was no significant difference in serum monoamine oxidase activities related to age and sex, platelet monoamine oxidase manifested a significant increase in females compared to males (p < 0.05) and the mean values in both sexes showed an increase with age (p < 0.001). The results of this study imply that platelet monoamine oxidase shows an age related increase which is more prominent in females.

Glucose Metabolism and Catecholamine Responses during Physical Exercise in Non-Insulin-Dependent Diabetes

Blood glucose, lactate, insulin, C-peptide, norepinephrine and epinephrine concentrations were determined in non-insulin-dependent diabetic patients and in healthy controls before, during and after moderate exercise, to evaluate the effects of physical exercise on glucoregulation. Ten diabetic and ten healthy control females bicycled 14 minutes at 60% of their maximal heart rates. In the diabetic patients, there were no significant changes in blood glucose levels post-exercise, while in controls the 60 minute post-exercise levels were higher than those measured in mid-exercise (p < 0.05). Lactate concentrations increased with exercise in both groups in a similar manner, with highest values at the end of exercise. No significant changes in insulin and C-peptide levels were induced with exercise in either group. Norepinephrine and epinephrine concentrations increased 2.5-3 fold with exercise in both groups (p < 0.05 for all values) but in the diabetics an earlier and prolonged catecholamine response was observed. We propose that catecholamines prevent hypoglycaemia during exercise when changes in insulin and C-peptide do not occur. In diabetic patients with good metabolic control, the glucoregulatory response to exercise is not worse than in anthropometrically similar controls with similar levels of fitness.

Role of thiocyanate ion in metallothionein induction and in endogenous distribution of essential elements in the rat liver

Thiocyanate is the major toxic metabolite of hydrogen cyanide, a toxic substance the organism may be exposed to as a result of cigarette smoking or industrial pollution. The complex interactions existing between metals and metallothionein induction are well known. However, the possible role of thiocyanate, which is also an anion, has not been established yet. Considering the interactions between metals and the metallothioneins, in this study the relationship between thiocyanate and the in vivo distribution of hepatic metallothionein and zinc, copper, iron, calcium, magnesium, and manganese are investigated in rats. This study implies that thiocyanate has, to some extent, an effect on the in vivo expression of metallothionein and endogenous distribution of essential elements in rat liver. Elevated levels of metallothionein and changes in hepatic concentrations of essential elements have suggested a role for thiocyanate in cellular metabolism and it might reflect a direct role of thiocyanate on alteration of cellular functional activities.

Standardized method comparison for ACS:180 plus and Immulite sensitive PSA (sPSA) measurement methods

Abstract The aim of this study was to compare two immunoassay measurement methods, the ACS:180 Plus (Chiron Diagnostics) kit and the Immulite sPSA (DPC) kit. Method comparison analysis was performed according to EP9-A; approved guideline of NCCLS 51. Serum samples having a wide range of total prostate-specific antigen (PSA) concentrations were evaluated in split-sample analysis. F-test, t-test analysis and regression statistics were performed. In Deming regression analysis the coefficients were as follows; the slope=0.967; y-intercept=-0.148, r=0.989. An acceptable bias was seen since the systematical error was calculated to have a value less than the total allowable error calculated from biological variations. Non-parametric evaluation of the area under ROC curves for ACS:180 Plus and Immulite sPSA were 0.997 and 0.987, respectively. Diagnostic accuracy was at the level of p= 0.000 and no statistical difference was found between the two assay methods.

The effects of hydergine on the MAO activity of the aged and adult rat brain

Despite the fact that hydergine has been used in the treatment of dementia for many years, its mechanism of action is still not clear. Current studies imply that the major effect of hydergine may be the modulation of synaptic neurotransmission rather than solely increasing blood flow as was once thought. A prominent feature that accompanies aging is an increase in monoamine oxidase (MAO) levels which results in decreased availability of catecholamines in the synaptic cleft. The aim of this study was to determine the effects of hydergine on the MAO activity in different brain regions (cortex, olfactory bulb, hypothalamus, hippocampus, striatum, cerebellum) of old (30 months) and adult (12 months) male Sprague-Dawley rats. In cortex and olfactory bulb MAO levels were higher in the aged group. In hippocampus and hypothalamus hydergine treatment caused significant decreases in MAO levels. An interaction between age and hydergine treatment was observed in the hypothalamus, hippocampus and cerebellum. The hydergine effect was more pronounced in the aged group in the hypothalamus and cerebellum, and more pronounced in the adult in the hippocampus. Our findings imply that increased brain MAO activity in aging can be modified by hydergine treatment in some brain regions.