Stara Zagora, Bulgaria
Stara Zagora, Bulgaria

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Hadjiev D.I.,Medical University-Sofia | Mineva P.P.,Thracian University
Medical Hypotheses | Year: 2013

A transient elevated arterial blood pressure is common in acute ischemic stroke and is often associated with a poor prognosis. The underlying mechanisms of blood pressure elevation are not well understood and its management is still unresolved. This article focuses on pathophysiology and management of elevated blood pressure in acute ischemic stroke. There is evidence that the main causes of a transient blood pressure elevation in acute ischemic stroke are the focal cerebral hypoperfusion and the stress responses with neuroendocrine systems activation. Clinical trials have reported that blood pressure lowering in acute ischemic stroke may have detrimental effect, probably because of impaired cerebral autoregulation. However, quantitative assessment of cerebral perfusion has not been performed during emergency blood pressure reduction in acute ischemic stroke. We suggest that ultrasound carotid artery disease evaluation and cerebral hemodynamics monitoring using bilateral transcranial ultrasonography, during blood pressure management in acute ischemic stroke might contribute to maintaining of an adequate penumbral perfusion and prevent infarct enlargement. Such an approach could individualize the antihypertensive treatment in acute ischemic stroke and improve functional outcome. Prospective studies are needed to confirm such a treatment strategy. © 2012 Elsevier Ltd.


The role of the antihypertensive therapy in preventing cognitive disorders in elderly persons without a history of stroke is still a matter of debate. This article focuses on the pathogenesis of vascular cognitive disorders in hypertension and on the impact of antihypertensive treatment in their prevention. Cerebral white matter lesions, caused by small vessel disease and cerebral hypoperfusion, have been found in the majority of elderly hypertensives. They correlate with cognitive disorders, particularly impairments of attention and executive functions. Excessive blood pressure lowering in elderly patients with long-standing hypertension below a certain critical level, may increase the risk of further cerebral hypoperfusion because of disrupted cerebral blood flow autoregulation. As a result, worsening of the cognitive functions could occur, especially in cases with additional vascular risk factors. Five randomized, placebo-controlled trials have focused on the efficacy of antihypertensive treatments in preventing cognitive impairments in elderly patients without a prior cerebrovascular disease. Four of them have not found positive effects. We suggest that repeated neuropsychological assessments and ultrasonography for evaluation of carotid atherosclerosis, as well as cerebral hemodynamics monitoring could adjust the antihypertensive therapy with the aim to decrease the risk of cerebral hypoperfusion and prevent or slow down cognitive decline in elderly hypertensives. Prospective studies are needed to confirm such a treatment strategy. © 2010 Elsevier Ltd.


Ivanov I.T.,Thracian University | Zheleva A.,Thracian University | Zlatanov I.,Bulgarian Academy of Science
International Journal of Hyperthermia | Year: 2011

4,4′-Diiso-thiocyanato stilbene-2,2′-disulphonic acid (DIDS) is a membrane-impermeable, highly specific covalent inhibitor and powerful thermal stabiliser of the anion exchanger (AE1), the major integral protein of erythrocyte membrane (EM). Suspensions of control and DIDS-treated (15μM, pH 8.2) human erythrocytes were heated from 20° to 70°C using various but constant heating rates (1-8°C/min). The cellular electrolyte leakage exhibited a sigmoidal response to temperature as detected by conductometry. The critical midpoint temperature of leakage, Tmo, extrapolated to low heating rate (0.5°C/min) was used as a measure for EM thermostability. Tmo was greater for DIDS-treated erythrocytes, 63.2°±0.3°C, than for intact erythrocytes, 60.7°±0.2°C. The time, t1/2, for 50% haemolysis of erythrocytes, exposed to 53°C was used as a measure for the resistance of erythrocytes against thermal haemolysis. The t1/2 was also greater for DIDS-treated erythrocytes, 63±3min, than for intact erythrocytes, 38±2min. The fluorescent label N-(3-pyrenyl)maleimide and EPR spin label 3-maleimido-proxyl, covalently bound to sulphydryl groups of major EM proteins, were used to monitor the changes in molecular motions during transient heating. Both labels reported an intensification of the motional dynamics at the denaturation temperatures of spectrin (50°C) and AE1 (67°C), and, surprisingly, immobilisation of a major EM protein, presumably the AE1, at Tmo. The above results are interpreted in favour of the possible involvement of a predenaturational rearrangement of AE1 copies in the EM thermostability and the resistance against thermal haemolysis. © 2011 Informa UK Ltd.


Marinova M.H.,Thracian University | Georgiev B.B.,Bulgarian Academy of Science | Vasileva G.P.,Bulgarian Academy of Science
Systematic Parasitology | Year: 2015

Diorchis thracica n. sp. (Cestoda, Cyclophyllidea, Hymenolepididae) is described from the ruddy shelduck Tadorna ferruginea (Pallas) (Aves, Anseriformes, Anatidae), collected in the vicinities of Radnevo, Stara Zagora Region, Bulgaria. The new species is differentiated from other members of Diorchis Clerc, 1903 by possessing rostellar hooks with length of 36 µm, a thick-walled cirrus-sac with strong longitudinal muscular fibres in its middle part and a copulatory vagina with two sphincters. Main morphological criteria for distinguishing species of the genus Diorchis are discussed. © 2015, Springer Science+Business Media Dordrecht.


Thermal analysis of suspension impedance was applied at various frequencies, f, to study the changes in erythrocyte membranes (EM) over the temperature interval 47-53 °C where spectrin denatures. At f < crossover frequency (cof1) a decrease in EM resistance at 49.5 °C (A peak) has been observed. At f > cof1, when the capacitive conductance of EM becomes dominant, a second peak appeared at 50.5 °C (anti-A peak). The amplitudes of A and anti-A peaks reversibly depended on the phosphorylation of EM proteins. In contrast to the A peak, the anti-A peak was totally eliminated by modifications of EM with reagents that reduce EM deformability, OsO4 (0.4-1 mM) and putrescine (cytosolic concentration 1.5-2.0 mM). © 2009 Elsevier B.V. All rights reserved.


Todorova R.,Bulgarian Academy of Science | Atanasov A.T.,Thracian University
Natural Product Research | Year: 2015

This review discusses the potential of Haberlea rhodopensis as a food additive. The following are described: plant distribution, reproduction, cultivation, propagation and resurrection properties; extraction, isolation and screening of biologically active compounds; metabolite changes during dehydration; phytotherapy-related properties such as antioxidant potential and free radical-scavenging activities, antioxidant skin effect, antibacterial activity, cytotoxic activity and cancer-modulating effect, radioprotective effect, chemoprotective effect, immunologic effect; present use in homoeopathy and cosmetics, pharmacological and economical importance; perspectives based on the ethnobotanical data for medicinal, cosmetic or ritual attributes. H. rhodopensis showed unique medical and pharmaceutical potential, related to antioxidant, antimicrobial, antimutagenic, anticancer, radioprotective, chemoprotective and immunological properties. H. rhodopensis extracts lack any cytotoxic activity and could be used in phytotherapy. The metabolic profiling of H. rhodopensis extracts revealed the presence of biologically active compounds, possessing antiradical and other physiological activities, useful for design of in vitro synthesised analogues and drugs. © 2015 Taylor & Francis


Ivanov I.T.,Thracian University | Paarvanova B.,Thracian University | Slavov T.,Thracian University
Bioelectrochemistry | Year: 2012

Polarization of spectrin-actin undermembrane skeleton of red blood cell (RBC) plasma membranes was studied by impedance spectroscopy. Relatedly, dielectric spectra of suspensions that contained RBCs of humans, mammals (bovine, horse, dog, cat) and birds (turkey, pigeon, duck), and human RBC ghost membranes were continuously obtained during heating from 20 to 70. °C. Data for the complex admittance and capacitance were used to derive the suspension resistance, R, and capacitance, C, as well as the energy loss as a function of temperature. As in previous studies, two irreversible temperature-induced transitions in the human RBC plasma membrane were detected at 49.5. °C and at 60.7. °C (at low heating rate). The transition at 49.5. °C was evident from the abrupt changes in R, and C and the fall in the energy loss, due to dipole relaxation. For the erythrocytes of indicated species the changes in R and C displayed remarkable and similar frequency profiles within the 0.05-13. MHz domain. These changes were subdued after cross-linking of membranes by diamide (0.3-1.3. mM) and glutaraldehyde (0.1-0.4%) and at the presence of glycerol (10%). Based on the above results and previous reports, the dielectric changes at 49.5. °C were related to dipole relaxation and segmental mobility of spectrin cytoskeleton. The results open the possibility for selective dielectric thermolysis of cell cytoskeleton. © 2012 Elsevier B.V.


Ivanov I.T.,Thracian University | Paarvanova B.,Thracian University
Bioelectrochemistry | Year: 2016

We studied the effect of spectrin denaturation at 49.5 °C (TA) on the dielectric relaxations and related changes in the complex impedance, Z*, complex capacitance, C*, and dielectric loss curve of suspensions containing human erythrocytes, erythrocyte ghost membranes (EMs) and Triton-X-100 residues of EMs. The loss curve prior to, minus the loss curve after TA, resulted in a bell-shaped peak at 1.5 MHz. The changes in the real and imaginary components of Z* and C* at TA, i.e., δZre, δZim, δCre and δCim, calculated in the same way, strongly varied with frequency. Between 1.0 and 12 MHz the -δZim vs δZre, and δCim vs δCre plots depicted semicircles with critical frequencies, fcr, at 2.5 MHz expressing recently reported relaxation of spectrin dipoles. Between 0.02 and 1.0 MHz the -δZim vs δZre plot exhibited another relaxation whose fcr mirrored that of beta relaxation. This relaxation was absent on Triton-X-shells, while on erythrocytes and EMs it was inhibited by selective dissociation of either attachment sites between spectrin and bilayer. Considering above findings and inaccessibility of cytosole to outside field at such frequencies, the latter relaxation was assumed originating from a piezoelectric effect on the highly deformable spectrin filaments. © 2016 Elsevier B.V.


PubMed | Thracian University
Type: | Journal: Bioelectrochemistry (Amsterdam, Netherlands) | Year: 2016

We studied the effect of spectrin denaturation at 49.5C (TA) on the dielectric relaxations and related changes in the complex impedance, Z*, complex capacitance, C*, and dielectric loss curve of suspensions containing human erythrocytes, erythrocyte ghost membranes (EMs) and Triton-X-100 residues of EMs. The loss curve prior to, minus the loss curve after TA, resulted in a bell-shaped peak at 1.5MHz. The changes in the real and imaginary components of Z* and C* at TA, i.e., Zre, Zim, Cre and Cim, calculated in the same way, strongly varied with frequency. Between 1.0 and 12MHz the -Zim vs Zre, and Cim vs Cre plots depicted semicircles with critical frequencies, fcr, at 2.5MHz expressing recently reported relaxation of spectrin dipoles. Between 0.02 and 1.0MHz the -Zim vs Zre plot exhibited another relaxation whose fcr mirrored that of beta relaxation. This relaxation was absent on Triton-X-shells, while on erythrocytes and EMs it was inhibited by selective dissociation of either attachment sites between spectrin and bilayer. Considering above findings and inaccessibility of cytosole to outside field at such frequencies, the latter relaxation was assumed originating from a piezoelectric effect on the highly deformable spectrin filaments.


PubMed | Thracian University and Bulgarian Academy of Science
Type: Journal Article | Journal: Natural product research | Year: 2016

This review discusses the potential of Haberlea rhodopensis as a food additive. The following are described: plant distribution, reproduction, cultivation, propagation and resurrection properties; extraction, isolation and screening of biologically active compounds; metabolite changes during dehydration; phytotherapy-related properties such as antioxidant potential and free radical-scavenging activities, antioxidant skin effect, antibacterial activity, cytotoxic activity and cancer-modulating effect, radioprotective effect, chemoprotective effect, immunologic effect; present use in homoeopathy and cosmetics, pharmacological and economical importance; perspectives based on the ethnobotanical data for medicinal, cosmetic or ritual attributes. H. rhodopensis showed unique medical and pharmaceutical potential, related to antioxidant, antimicrobial, antimutagenic, anticancer, radioprotective, chemoprotective and immunological properties. H. rhodopensis extracts lack any cytotoxic activity and could be used in phytotherapy. The metabolic profiling of H. rhodopensis extracts revealed the presence of biologically active compounds, possessing antiradical and other physiological activities, useful for design of in vitro synthesised analogues and drugs.

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