Gorazd Drevenšek

University of Ljubljana · Faculty of Medicine

Several studies indicate the influence of olanzapine on bone metabolism; however, the results are contradictory. We evaluated the effects of olanzapine on the Wnt/β-catenin signaling pathway, physiological alveolar bone turnover, and alveolar bone modeling due to an applied orthodontic force. Adult male rats (n=48) were treated with either olanzapi...

Background: In recent years, authors have repeatedly reported on the significance of social support in cancer survival. Although overall the studies appear to be convincing, little is known about which types of social support promote better survival rates, and which subgroups of cancer patients are more susceptible to the benefits of it. The aim o...

With advanced age, there is a loss of reaction speed that may contribute to an increased risk of tripping and falling. Avoiding falls and injuries requires awareness of the threat, followed by selection and execution of the appropriate motor response. Using event-related potentials (ERPs) and a simple visual reaction task (RT), the goal of our stud...

Introduction Current nutritional strategies for people with dementia focus on nutritional diets and regimens, although in recent years congruent care for people with dementia has been increasingly recognized to improve their wellbeing. This includes consistency of care, respecting the variability of psycho-sociological factors, emphasizing the impo...

Objective: Fatal reactions to the combination of ketamine-medetomidine and thiopental in Wistar rats are described in two different models of orthodontic tooth movement. Materials and methods: Thirty male rats were divided into two groups that required repeated anaesthesia during a 42-day study period, once a week or more frequently depending on...

Background: Diabetes, among multiple systemic harmful health issues, also may deteriorate normal regenerative and reparative functions of periodontium. The aim of this research was to study the role of periodontal ligament in tissue remodeling under the orthodontic appliance stimulation in two rat experimental models (healthy Wistar rats and Goto-...

Background Previous studies on dental anxiety have examined the psychophysiological responses evoked in dentally anxious subjects by dental-related stimuli, but not during a real-life dental examination, which was achieved in the present study.Methods The heart rate, skin conductance level, and heart rate variability of 25 subjects with dental anxi...

The endothelin system has an important role in bone modelling during orthodontic tooth movement (OTM); however, little is known about the involvement of endothelin B receptors (ETB) in this process. The aim of this study was to evaluate the role of ETB in bone modelling during OTM using ETB knockout rats (ETB-KO). Thirty-two male rats were divided...

Background: Many risk factors lead to opioid use and drug-related problems. One of the challenges to understand behavioural factors, drug problems and psychopathology is to identify biological markers that are suitable for research on broad substance abuse and dependence involving human participants. Aims: The study has examined the relationships b...

Background: This study has examined the relationships and interactions between serum brain-derived neurotrophic factor (BDNF) levels, BDNF Val66Met polymorphism and self-reported risk-taking behaviour in individuals with a history of heroin use undergoing outpatient treatment in comparison to healthy individuals. Methods: We enrolled 167 heroin...

Background: Statins and sartans can, in therapeutic doses, induce pleiotropic cardiovascular effects. Similar has recently been shown also for sub-therapeutic doses. We thus explored and compared the cardiovascular pleiotropic efficacy of sub-therapeutic vs. therapeutic doses. Methods: Wistar rats were randomly divided into 7 groups receiving fluva...

Background: Silver fir trunk extract (SFTE) is a complex mixture of antioxidative polyphenols (lignans and phenolic acids) from the trunks of silver fir trees (Abies alba, lignum). In our previous study, we have shown that SFTE exerts strong antioxidative and protective effects against atherogenic, diet-induced arterial wall damage. Objective: T...

The use of zinc oxide nanoparticles (ZnO NPs) in numerous products is increasing, although possible negative implications of their long-term consumption are not known yet. Our aim was to evaluate the chronic, 6-week oral exposure to two different concentrations of ZnO NPs on isolated rat hearts exposed to ischemic-reperfusion injury and on small in...

Treatment with low, subtherapeutic doses of statins and sartans expresses beneficial pleiotropic effects on the arterial wall. The present study explored whether these effects depend on treatment duration. Wistar rats were randomly divided into 4 groups and received low-dose atorvastatin, low-dose losartan, their combination, or saline (control) da...

Introduction: Type 2 diabetes is known to affect bone metabolism. In this study, we aimed to determine the effects of type 2 diabetes on bone remodeling during orthodontic tooth movement. Methods: The 48 rats were divided into 4 groups: Wistar control group (n = 8), Goto-Kakizaki (GK) control group (n = 8), Wistar appliance group (n = 16), and G...

T he increase in the production of nanomaterials in the past decades introduced both positive and negative prospects in the consumer goods. ZnO nanoparticles are amongst the most frequently used and globally produced nanomaterials. Oral ingestion is one of the already acknowledged exposure routes for the unintentional consumption of ZnO nanoparticl...

Diet, rich in plant polyphenols prevents atherogenesis that manifests as reduced vascular relaxation and formation of plaques. Atherosclerosis could be reduced by the intake of silver fir (Abies alba) extract (SFTE), rich in polyphenols. Chronic, in vivo treatment animal study. Guinea pigs (Cavia porcellus) were fed for 8 weeks with one of the foll...

New preventive strategies for atherosclerosis are needed. In this study, we tested whether a new therapeutic approach consisting of low dose treatment with a statin and sartan combination could prevent atherogenic diet-induced impairment of the arterial wall in guinea pigs. Twenty-five Dunkin-Hartley guinea pigs were randomly assigned to five exper...

Delivery of therapeutic proteins into tissues and across the blood-brain barrier (BBB) is limited by the size and biochemical properties of the proteins. Efficient delivery across BBB is generally restricted to small, highly lipophilic molecules. However, in the last decades, several peptides that can pass cell membranes have been identified. It ha...

Recently it has been shown that statins and angiotensin receptor blockers (ARBs) at low doses express beneficial pleiotropic vascular effects. We aimed to explore whether these drugs at low doses induce the expression of vasoactive-related genes. Sixty adult Wistar rats were treated with low-dose atorvastatin (2 mg/kg), low-dose losartan (5 mg/kg),...

The cardiovascular pleiotropic effects of statins and angiotensin receptor blockers (ARBs) could be of interest for innovative preventive approaches. We aimed to investigate whether low-dose atorvastatin and losartan, separately not possessing protective cardiovascular pleiotropic effects, express them when combined. Forty-five adult male Wistar ra...

Statins and angiotensin receptor blockers at therapeutic doses have beneficial cardiovascular effects, which can be applied for cardiovascular protection. We explored whether low doses of atorvastatin, losartan, and particularly their combination, possess important pleiotropic vasodilatory effects. Wistar rats were treated daily with low-dose atorv...

Background and aims: Anthocyanins, a sub-class of flavonoids, induce endothelium-dependent vasorelaxation, by activating endothelial nitric oxide synthase and consequently increasing production of the vasorelaxant agent nitric oxide. It is not yet clear if anthocyanin-induced vasorelaxation starts with their interaction with plasma membrane recept...

Endothelin 1 (ET-1) is vasoactive peptide that acts via ET-A receptors coupling inducing vascular smooth muscle cell proliferation and contraction. ET-1 is involved in the development and maintenance of hypertension. Aim of this study was to determine the contribution of Ras farnesyl transferase, mitogen activated protein kinase (MAP kinase) and cy...

Histamine (H(1)) receptor antagonists are widely used drugs for treatment of allergic conditions. Although histamine was shown to be involved in bone remodeling, the aim of this study was to determine the effects of cetirizine, an H(1) receptor antagonist, on bone modeling processes during orthodontic tooth movement. We used 3 groups of Wistar rats...

Background: Statins are recognised as the most effective lipid-lowering drugs. The main mechanism of action is the inhibition of 3-hydroxy- 3-methylglutaryl-coenzyme A reductase, which is a key enzyme in the cholesterol synthesis pathway. Statins also have additional effects, known as pleiotropic effects, which are mostly due to the inhibition of t...

Despite being reported to reduce the risk of cardiovascular diseases, little is known about acute direct effects of bilberry anthocyanins on whole mammalian heart under ischemia-reperfusion (I-R) conditions. Bilberry anthocyanins were prepared from the ripe bilberries and analyzed using HPLC-DAD. Their antioxidant activity was evaluated by measurin...

Endothelins (ETs) are a family of three peptides (ET-1, ET-2, ET-3) that are implicated in the physiological control of vascular smooth muscle cell (VSMC) and myocardial contractility and growth. ET-1 is vasoactive peptide that acts via ET-A receptors coupling inducing vascular smooth muscle cell contraction. ET-1 is involved in the development and...

Endothelins (ET)-1, ET-2, and ET-3 are one group of cytokines likely to be released during orthodontic tooth movement (OTM). Therefore, the expression of ET levels was investigated to determine the importance and involvement of isopeptides during the several phases of OTM. Thirty-two male Wistar rats (12–13 weeks old) were divided into four groups...

. The latter can be ascribed to an efficientamplification cycle whereby bilirubin, acting as antioxi-dant, is itself oxidized to biliverdin and then recycled backto bilirubin by NADPH-dependent biliverdin reductase.Bilitranslocase, a bilirubin-specific membrane carrier thatmediates cellular uptake of bilirubin, has recently beenfound in the vascula...

The aim of this study was to determine whether a force applied in an antero-posterior direction would adequately reduce incisor eruption. This is needed to achieve a constant direction of force which is one of the demands for a good model for studying orthodontic tooth movement. Twenty male Wistar rats aged 11–12 weeks were divided into two equal g...

The endothelin system is involved in orthodontic tooth movement (OTM). The aim of the study was to examine the role of ET-1, ET(A) and ET(B) in bone modeling during OTM in rats. Male Wistar rats (n=62) were divided into three groups: control animals (n=10; control group) without appliance, and two groups of experimental animals, which were applied...

The vasomotor response of the coronary artery is altered by hypoxia-reoxygenation (H-R) induced damage. The aim of our study was to compare and evaluate normothermic and hypothermic models which are suitable for future drug studies of vasoprotective action against H-R injury. Porcine coronary arterial rings were isolated and placed in Krebs-Hensele...

Many chemical messengers are involved in the process of alveolar bone and periodontal ligament remodelling during orthodontic tooth movement. Among them is probably endothelin-1 (ET-1). Its role in this process has been partly explained using tezosentan, which affects endothelin A (ETA) and endothelin B (ETB) receptors. Tezosentan enhances orthodon...

Flavonoids are polyphenols, Those are compounds with 15 carbon atoms of type C-6, C-3-C-6. Flavonoid structures differ in position of the and hydroxylation, presence of carbonyl. group on C4 atom, presence of-OH group on C3 atom, oxidation status of the ring C, and in kind, number and position of sacharide remnants bound to flavonoid structure.. Th...

To establish potential anti-ischemic effects of testosterone and estradiol on myocardium we used isolated rat hearts in accordance with Langendorff, exposed to 40 min of ischemia and reperfusion. Rats were pretreated for 10 days, males with testosterone and females with estradiol and injuries from those hearts were compared to the hearts where both...

.

Endothelin is a cytokine peptide present in the periodontal ligament in physiological conditions. Its concentration in the periodontal ligament doubles after 3 hours of axial loading of a tooth. The role of endothelin in orthodontic tooth movement has not yet been explained. We tried to determine the effect of tezosentan, a specific dual endothelin...

The main structural feature of direct thrombin inhibitor LK-732 responsible for the appropriate interaction at the thrombin active site is a strong basic group. A possibility that a strong basic group of LK-732 might contribute to the mast cell degranulation effect and consequent reduction of tracheal air flow (TAF) and fall of mean arterial blood...

The antithrombotic potential of new direct thrombin inhibitors built on the azaphenylalanine scaffold (LK-732, LK-639 and LK-731) and their amidoxime prodrugs (LK-658, LK-633 and LK-730) was studied in comparison to argatroban and nadroparin in two rat models of venous thrombosis, induced either by complete stasis combined with hypercoagulability (...

The superficial regions of the dog splanchnic nerve were selectively stimulated with 33-electrode spiral cuffs in 11 circumferential groups of three electrodes to modulate the function of the innervated internal organs and glands. In two adult Beagle dogs under general anaesthesia, the cuffs were chronically implanted on the nerve trunks before the...

Vasomotor response of the coronary artery depends on both endothelial and smooth muscle cells. Response is altered by hypoxia-reoxygenation-induced damages. Hypoxic preconditioning and pharmacological preconditioning as well can prevent these alterations. We compared the effectiveness of both types of preconditioning against hypoxia-reoxygenation-i...

In the present study we examined the endothelium-dependent mechanism in the constriction of the isolated porcine coronary artery induced by Equinatoxin II (EqT II). EqT II is a polypeptide isolated from the sea anemone (Actinia equina, L.). Contractions induced by endothelin-1 (ET-1) were compared with the contractions induced by EqT II. The force...

Equinatoxin II (EqT II) is a basic, cardiotoxic polypeptide. The vasoconstrictory effect of the toxin on isolated porcine coronary arteries was diminished by nicardipine, an L-type calcium channel antagonist. A comparison was made of the effects of EqT II alone and EqT II in the presence of nicardipine on the coronary flow in porcine and rat hearts...

Equinatoxin II (EqT II) decreases coronary flow in guinea-pig and rat heart. It increases cytosolic Ca2+ activity and is supposed to form cation selective membrane pores. In the present study we tried to evaluate the influence of the L-type Ca2+ channel antagonist nicardipine upon the vasoconstrictory effect of EqT II on coronary vessels in isolate...

Equinatoxin II (EqT II) is a basic polypeptide toxin from the sea anemone Actinia equina (L.). Its LD50 in mice is 33 g/kg. The cause of death after intravenous application has been attributed to the circulatory failure resulting in the cardiotoxic effects. In Langendorff’s rat and guinea-pig heart preparations EqT II caused dose dependent decrease...

Equinatoxin II (EqT II) is a basic polypeptide toxin from the sea anemone Actinia equina (L.). Its LD50 in mice is 33 g/kg. The cause of death after intravenous application has been attributed to the circulatory failure resulting in the cardiotoxic effects. In Langendorff's rat and guinea-pig heart preparations EqT II caused dose dependent decrease...

The venom of the honeybee Apis mellifera induces cardiovascular dysfunction. As its effects on coronary arteries have not yet been described, we studied the effects of the whole honeybee venom (non-volatile part) in the isolated porcine left anterior descending coronary artery (LAD) and the influence of L-type Ca2+ channel blocker, lacidipine, upon...

The porcine heart was used as a model for studying the thermal changes in myocardium at cooling and re-warming during open heart surgery. A section of the heart septum was excised and tissue was cut into two similar square slices. The same shape of the tissue, cut from the surface from the upper lateral wall of the left ventricle, covered with epic...

Death after i.v. administration of equinatoxin II (EqT II) has been attributed to the circulatory failure resulting from cardiotoxic effects. The mechanism of action is unknown. The aim of the present work was to study the effects of the toxin on vascular tone in the isolated porcine coronary artery and on coronary flow in the isolated pig heart. E...

In isolated human anterior tibial artery the effects of two different types of calcium channel antagonists, mibefradil (a selective T-type Ca2+ channel antagonist) and lacidipine (a 1,4 dihydropyridine Ca2+ channel antagonist, acting at L- and T-type, but binds preferentially at L-type Ca2+ channels) were compared. Both drugs reduced the contractio...

Equinatoxin II is a lethal basic protein isolated from the sea anemone Actinia equina (L.) with ld50 in mice 35 μg/kg. The putative cause of death is cardiorespiratory arrest, but the mechanism of cardiotoxicity is poorly understood. It is not clear whether the toxin injected intravenously into an experimental animal reaches the heart in a concentr...

In isolated rat hearts effects of chloropyramine (CP), histamine H1 antagonist, and famotidine (FA), H2 antagonist, upon two different myocardial injuries, ischaemia-reperfusion and hypoxia-reoxygenation were studied. In both types of injury the effects of drugs were seen mainly during reperfusion and reoxygenation, respectively. During reperfusion...

The left ventricular pressure (LVP) and ECG signals that appear during and after ischaemia tend to be very irregular (fibrillation, arrhythmia). Computer based data acquisition system, that we developed to support experiments on isolated Langendorff's rat heart, enabled the usage of methods derived from non-linear dynamics. To classify the irregula...