Joanna Saluk

Melatonin Redox Activity. Its Potential Clinical Applications in Neurodegenerative Disorders

Neurodegeneration is the hallmark of many chronic progressive neurogical disorders characterized by specific clinical, morphological and biochemical features. Central nervous system is very sensitive to oxidative stress, which is considered as a key factor of neurodegenerative disorders. Therefore, many therapeutical strategies are focused on molecules with redox activity to re-establish the equilibrium between pro and antioxidants. Due to the fact that melatonin readily crosses the blood- brain-barrier, concomitant with its safety profile at the highest dosages makes this dietary supplement very useful in possible clinical application in neurodegeneration. Melatonin is currently marketed in several countries as a dietary supplement with no prescription. Clinical trials have shown different effectiveness of melatonin supplementation in several disorders, including neurodegenerative disorders. Melatonin has unique biochemical properties such as scavenging of hydroxyl, carbonate, alkoxyl, peroxyl and aryl cation radicals and stimulation of activities main antioxidative enzymes (glutathione peroxidase, superoxide dismutase etc.). Moreover, it can suppress nitric oxide synthase. The present paper highlighted the potential clinical role of melatonin in main neurodegenerative diseases including Alzheimer disease, Parkinson disease, amylotrophic lateral sclerosis and multiple sclerosis. Moreover, in this review the main molecular aspects of melatonin in brain cell protection and survival mechanisms were discussed. Therefore, melatonin is regarded as a potential therapeutical agent in clinical application in neurodegenerative disorders, but this findings needs to be confirmed by the larger, more well-designed clinical trials.

Radical scavenging and antioxidant effects of Matricaria chamomilla polyphenolic-polysaccharide conjugates.

Matricaria chamomilla L. (MC), a member of the Asteraceae family, is one of the oldest medicinal plants, widely used worldwide for a variety of healing applications. Its recommendations, derived from both traditional and modern medicine, include numerous disorders such as inflammation, ulcers, wounds, gastrointestinal disorders, stomach ache, pharyngitis, rheumatic pain, as well as the other ailments. This work is focused on another aspect of the biological activity of chamomile polyphenolic-polysaccharide conjugates--their antioxidant properties in the protection of blood plasma components against in vitro oxidative stress. Measurements of DPPH and ABTS radical scavenging indicated considerable anti-free radical action of MC. Pre-incubation of blood plasma with MC considerably diminished the extent of ONOO(-)-induced oxidative modifications such as protein carbonyl groups, SH groups, 3-nitrotyrosine, as well as the formation of lipid hydroperoxides. The analysis of the FRAP assay result shows a considerable increase of ferric reducing ability of blood plasma in the presence of MC. The results obtained in this study indicate that polyphenolic-polysaccharide conjugates isolated from M. chamomilla substances possess antioxidant properties. The M. chamomilla macromolecular glycoconjugates may be useful in the creation of new natural-based medications or dietary supplements, helpful in the prevention and treatment of oxidative stress-mediated disorders.

Poststroke Depression as a Factor Adversely Affecting the Level of Oxidative Damage to Plasma Proteins during a Brain Stroke

Poststroke depression, the second most serious psychosomatic complication after brain stroke, leads to delay of the rehabilitation process and is associated with an increased disability and cognitive impairment along with increase in term mortality. Research into the biochemical changes in depression is still insufficiently described. The aim of our study was therefore to evaluate the possible association between plasma protein oxidative/nitrative damages and the development of poststroke depression. We evaluated oxidative/nitrative modifications of specific proteins by measurement of 3-nitrotyrosine and carbonyl groups levels using ELISA test. Additionally, we checked differences in proteins thiol groups by spectrophotometric assay based on reaction between DTNB and thiols. We also evaluated catalase activity in erythrocytes measured as ability to decompose H2O2. Correlation analysis was performed using Spearmans rank. We observed significant (P < 0.001) differences in all oxidative/nitrative stress parameters in brain stroke patients compared to healthy group. Our research shows that oxidative damage of proteins is correlated with the degree of poststroke depression, while nitrative changes do not show any relationship. We demonstrate a positive correlation between the concentration of carbonyl groups and the Geriatric Depression Scale and a negative correlation between the degree of depression and the concentration of -SH groups or catalase activity.

Red cabbage anthocyanins as inhibitors of lipopolysaccharide-induced oxidative stress in blood platelets

LPS is a Gram-negative bacteria endotoxin, which is an important pro-inflammatory agent. Blood platelets take part both in inflammatory processes and in pathogenesis of septic shock following accumulation of LPS. As a platelet agonist LPS causes the intraplatelet overproduction of ROS/RNS that are responsible for adverse modifications in the structure of platelet compounds being associated with a development of platelet-dependent diseases. Existing evidence suggests that anthocyanins (ATH) are able to protect the circulatory system. The antioxidative properties of ATH are believed to be mainly responsible for their positive health effects. The main goal of the present in vitro study was to investigate the potential protective properties of red cabbage ATH against oxidative damage induced by LPS in blood platelets. Exposure of platelets to LPS resulted in carbonyl group increase, 3-nitrotyrosine formation, lipid peroxidation and O2(•-) generation. We have shown that ATH extract effectively decreased oxidative stress induced by LPSs. The in silico analysis demonstrated that both cyanin and LPS were located at the same region of human TLR4-MD-2 complex. Our findings suggest that there could be two-way ATH platelet protection mechanism, by their antioxidant properties and directly by binding with TLRs.

Metformin - The Drug for the Treatment of Autoimmune Diseases; A New Use of a Known Anti-Diabetic Drug

Autoimmune diseases are characterized by the production of autoantibodies directed against specific organs of own organism. Additional common traits of autoimmune diseases are chronic inflammation due to generation of inflammatory mediators, and disorders of redox processes. The pathogenesis of autoimmune diseases is still unknown. Treatment is based only on relieving the symptoms and improving the quality of patients lives. Metformin, which is used in treatment of type 2 diabetes, has properties which are desirable for autoimmune disease therapy, including anti-inflammatory and antioxidant effects, and the ability to regenerate the endothelium.

The synthesis of proteins in unnucleated blood platelets

Platelets are the smallest, unnucleated blood cells that play a key role in maintaining normal hemostasis. In the human body about 1x1011 platelets are formed every day, as a the result of complex processes of differentiation, maturation and fragmentation of megakaryocytes. Studies done over 4 decades ago demonstrated that circulating in blood mature platelets can synthesize proteins. Recent discoveries confirm protein synthesis by unnucleated platelets in response to activation. Moreover, protein synthesis alters the phenotype and function of platelets. Platelets synthesize several proteins involved in hemostasis (COX, αIIbβ3, TF PAI-1, Factor XI, protein C inhibitor) and in inflammatory process (IL-1β, CCL5/RANTES). In spite of lack of transcription platelets have a stable mRNA transcripts with a long life correlated with platelet life span. Platelets also show expression of two important key regulators of translation eIF4E and EIF-2α and have a variety of miRNA molecules responsible for translational regulation. This article describes the historical overview of research on protein synthesis by platelets and presents the molecular mechanisms of protein synthesis in activated platelets (and synthesis of the most important platelet proteins).

Relationship between the Increased Haemostatic Properties of Blood Platelets and Oxidative Stress Level in Multiple Sclerosis Patients with the Secondary Progressive Stage.

Multiple sclerosis (MS) is the autoimmune disease of the central nervous system with complex pathogenesis, different clinical courses and recurrent neurological relapses and/or progression. Despite various scientific papers that focused on early stage of MS, our study targets selective group of late stage secondary progressive MS patients. The presented work is concerned with the reactivity of blood platelets in primary hemostasis in SP MS patients. 50 SP MS patients and 50 healthy volunteers (never diagnosed with MS or other chronic diseases) were examined to evaluate the biological activity of blood platelets (adhesion, aggregation), especially their response to the most important physiological agonists (thrombin, ADP, and collagen) and the effect of oxidative stress on platelet activity. We found that the blood platelets from SP MS patients were significantly more sensitive to all used agonists in comparison with control group. Moreover, the platelet hemostatic function was advanced in patients suffering from SP MS and positively correlated with increased production of O2 −∙ in these cells, as well as with Expanded Disability Status Scale. We postulate that the increased oxidative stress in blood platelets in SP MS may be primarily responsible for the altered haemostatic properties of blood platelets.

[The formation, metabolism and the evolution of blood platelets].

Platelets are the smallest, depleted of nucleus blood cells which contain a typical cellular organelles including the mitochondria, so that have active metabolism. Platelets possess the highly organized cytoskeleton, specific secretory granules and unique membrane receptors system responsible for their high reactivity. The key role of blood platelets is to maintain normal hemostasis, but they also play important roles in inflammation, immune processes and the cancer progression. The anucleated, small platelets occur in representatives of all clusters of mammals, so it seems to be an adaptation feature. In other vertebrates similar hemostatic functions are played by large nucleated platelets, which are much more weakly reactive. Small, reactive platelets, appearing in the evolution of mammals, allowed the formation of clots faster and slower blood loss in case of injury, but also increased the risk of thromboembolic and cardiovascular diseases. Daily the human body forms about 1x10¹¹ platelets, which are produced by a process of differentiation, maturation and fragmentation of the cytoplasm of mature megakaryocytes. The emergence of platelets is the final stage of megakaryocyte differentiation and is followed by formation of the direct precursors called proplatelets. The anucleated platelets are regarded as terminally differentiated cells, which are not capable of further cell division. However, despite the absence of a nucleus, in blood platelets the synthesis and transcription of mitochondrial DNA and protein synthesis occurring on the basis of mRNA from megakaryocytes has been confirmed. However, recent studies published in 2012 show that the platelets are capable not only of the process of protein synthesis, but also of generation of new cells, which are functionally and structurally similar to the parent platelets.

Platelets miRNA as a Prediction Marker of Thrombotic Episodes

The blood platelets are crucial for the coagulation physiology to maintain haemostatic balance and are involved in various pathologies such as atherosclerosis and thrombosis. The studies of recent years have shown that anucleated platelets are able to succeed protein synthesis. Additionally, mRNA translation in blood platelets is regulated by miRNA molecules. Recent works postulate the possibility of using miRNAs as biomarkers of atherosclerosis and ischemic episodes. This review article describes clinical studies that presented blood platelets miRNAs expression profile changes in different thrombotic states, which suggest use of these molecules as predictive biomarkers.

Extremely low frequency electromagnetic fieldreduces oxidative stress during the rehabilitationof post-acute stroke patients

BACKGROUNDnOne of the therapeutic methods used in stroke rehabilitation is magnetotherapy using extremely low frequency and variable pulse shape electromagnetic field (ELF-EMF).nnnOBJECTIVESnThe aim of our study was to investigate the effect of magnetotherapy on the condition of postacute stroke patients, as measured by plasma oxidative stress markers and clinical parameters which show the progress of rehabilitation.nnnMATERIAL AND METHODSnThe selected 57 post-stroke patients were divided into 2 groups, those with ELFEMF therapy and those without. The level of oxidative stress in the plasma was estimated by typical markers: thiobarbituric acid reactive substances (TBARS), thiol groups, and carbonyl groups. The effect of ELF-EMF on the course of the patients rehabilitation following ischemic stroke was evaluated with the use of scales of physical activity and mental state: Activities of Daily Living (ADL), Mini-Mental State Examination (MMSE) and Geriatric Depression Scale (GDS).nnnRESULTSnOur comparative analysis showed that all parameters of oxidative stress are significantly reduced during rehabilitation using ELF-EMF, compared to the control group rehabilitated only by kinesiotherapy. We also recorded much higher therapeutic benefits using magnetotherapy, which revealed a significant improvement of clinimetric parameters.nnnCONCLUSIONSnThe ELF-EMF therapy meaningfully improves the overall condition of patients through a decrease of oxidative stress markers and it significantly affects the psychophysical abilities of patients after stroke. The change in carbonyl group level correlates with the change in the degree of physical and mental disability; therefore, it could be a marker for the effectiveness of rehabilitation.