Dusan Mitrovic | University of Belgrade (original) (raw)

Papers by Dusan Mitrovic

Research paper thumbnail of Is 28-day follow-up period enough for examining the mortality after resuscitation with human albumin?

Hospital Pharmacology - International Multidisciplinary Journal, 2014

Objective The potential risk of mortality increase due to the use of human albumin (HA) in surgic... more Objective The potential risk of mortality increase due to the use of human albumin (HA) in surgical patients has not been determined yet. The aim of the study was to evaluate the association of mortality rate of surgical patients with other indicators of the quality of health services and consumption of HA and hydroxyethyl starch (HES). Methods The study of a time series at the surgical department analyzed monthly indicators of the quality of health services. The monthly consumption of HA and HES is shown as a number of HA or HES bottles consumed in the intensive care unit (ICU) or outside the ICU. Autoregressive integrated moving average (ARIMA) model was used for the statistical analysis. Results For the total mortality rate, four significantly predictors in moving average model were identified. The total mortality rates for each next month were significantly directly dependent on the unobserved random error from the current and previous month. Number of operated patients showed an indirect effect on the total mortality rate. Number of HA bottles consumed in the ICU, mortality rate of operated patients and patients without operation were directly associated with the increased total mortality rate. Conclusions Follow-up period for examination of the mortality from resuscitation with HA in a heterogeneous surgical population can not be less than two months. ARIMA can be extremely useful in determining a total period of time when all mortality due to the application of certain drug in a particular population will be manifested.

Research paper thumbnail of Penetration of 3H Tiazofurin from Blood into Guinea Pig Brain

Advances in Behavioral Biology, 1996

Transport of tiazofurin (2-β-D-ribofuranosyl thiazole-4-carboxamide) across the blood-brain barri... more Transport of tiazofurin (2-β-D-ribofuranosyl thiazole-4-carboxamide) across the blood-brain barrier (BBB) was studied using brain vascular perfusion method in the guinea pig. The obtained results demonstrate that brain clearance of 3H tiazofurin significantly differs from zero, suggesting that this molecule penetrates from blood into the brain. The values of tiazofurin brain clearance are very close to the values obtained for neuropeptides and other so called “slow penetrating molecules” (regarding the blood brain barrier). Addition of increasing concentrations of unlabelled tiazofurin to the perfusing medium caused a significant decrease in the uptake of [3H] labelled tiazofurin. Therefore, penetration of tiazofurin from blood into brain seems to be a saturable process. Presence of increasing concentrations of unlabelled adenosine has similar effect as the presence of unlabelled tiazofurin in the perfusing medium. However, it did not cause complete inhibition of tiazofurin brain uptake.

Research paper thumbnail of Characteristics of thiamin transport in the isolated perfused guinea pig heart

Archives Of Physiology And Biochemistry, 1993

The cellular uptake of (14C)-thiamin hydrochloride was studied in the isolated perfused guinea pi... more The cellular uptake of (14C)-thiamin hydrochloride was studied in the isolated perfused guinea pig heart, using the rapid single circulation, paired-tracer technique, in which D-(3H)-mannitol serves as an extracellular marker. Cellular uptake of this vitamin was estimated by directly comparing venous dilution profiles of (14C) and (3H) radioactivities in the absence and presence of unlabelled thiamin hydrochloride and pyrithiamin hydrobromide. The maximal cellular uptake (Umax) of thiamin was very low (5.31 +/- 1.79%), while in the presence of 10 mM unlabelled thiamin and 1 mM pyrithiamin, Umax was significantly greater (9.71 +/- 1.57% and 12.30 +/- 0.82%, respectively). Our data suggest that there is a saturable mechanism of sarcolemmal thiamin transport out of myocardial cell, while this transport into the cell is unsaturable.

Research paper thumbnail of Roles of sulfur-containing amino acids in gastrointestinal physiology and pathophysiology

Vojnosanitetski pregled, 2020

Research paper thumbnail of Suppression of methionine-induced colon injury of young rats by cysteine and N-acetyl-L-cysteine

Molecular and cellular biochemistry, Jan 17, 2017

Changes in the methionine metabolism can cause a state called hyperhomocysteinemia, inducing oxid... more Changes in the methionine metabolism can cause a state called hyperhomocysteinemia, inducing oxidative stress in the gut. The production of free radicals is important in the colon damage caused by methionine. This study aimed at evaluating the effect of the use of L-cysteine and N-acetyl-L-cysteine on the colon morphometry of young rats treated with methionine. A total number of 32 male rats were distributed in a randomized experimental design in 4 groups: control group treated with saline; methionine group; cysteine + methionine group, and N-acetyl-L-cysteine + methionine group. After 21 days of treatment, rats were sacrificed and the colon samples were taken for histological and biochemical analysis. Methionine load increased depth of crypts, the lamina muscularis mucosae thickness, the mucosal height, and the number of cells in lamina propria (p < 0.01). Combination of methionine with L-cysteine (C group) and with N-acetyl-L-cysteine (N group) reversed methionine effects. Meth...

Research paper thumbnail of Antioxidant effect of dry olive (Olea europaea L.) leaf extract on ethanol-induced gastric lesions in rats

Mediterranean Journal of Nutrition and Metabolism, 2009

gastric lesions induced. Furthermore, OLE was effective in the prevention of an increase in gastr... more gastric lesions induced. Furthermore, OLE was effective in the prevention of an increase in gastric lipid peroxidation and in the prevention of a decrease in antioxidative enzyme activity. The results obtained indicate that OLE has gastroprotective activity against ethanol-induced gastric lesions in rats, possibly related to its antioxidative properties.

Research paper thumbnail of Attenuation of cold restraint stress-induced gastric lesions by an olive leaf extract

General physiology and biophysics, 2009

Olive leaf extract (OLE) possesses, among other, antioxidative properties, but whether it influen... more Olive leaf extract (OLE) possesses, among other, antioxidative properties, but whether it influences gastroprotection against stress-induced gastric lesions remains unknown. In this study we investigated the protective effect of OLE, a natural antioxidant, on gastric mucosal damage induced by cold restraint stress (CRS) in rats. Three different doses of commercial OLE EFLA((R)) 943 were applied intragastrically (i.g.) 30 min prior to stress induction. Macroscopic gastric lesions were evaluated and ulcer index (UI) was calculated. Histological evidence of gastric mucosal lesions was also obtained. Concentration of malondialdehyde (MDA) as an index of lipid peroxidation, and catalase (CAT) and superoxide dismutase (SOD) activities were determined in gastric mucosa. The effects of applied OLE on gastric mucosal lesions, lipid peroxidation and antioxidative enzymes activity were compared with effects of i.g. pretreatment of reference drug, ranitidine. CRS caused severe gastric lesions i...

Research paper thumbnail of Properties of thiamin transport in isolated perfused hearts of chronically alcoholic guinea pigsThis article is one of a selection of papers published in the special issue Bridging the Gap: Where Progress in Cardiovascular and Neurophysiologic Research Meet

Canadian Journal of Physiology and Pharmacology, 2008

The aim of this study was to determine the mechanism of transport of 14C-thiamin in the hearts of... more The aim of this study was to determine the mechanism of transport of 14C-thiamin in the hearts of healthy (nonalcoholic) and chronically alcoholic guinea pigs. We used the single-pass, paired-tracer dilution method on isolated and retrogradely perfused guinea pig hearts. The maximal cellular uptake (Umax) and total cellular uptake (Utot) of 14C-thiamin were determined under control conditions and under influence of possible modifiers. We tested how the presence of unlabeled thiamin, metabolic inhibitors, or absence of sodium ions influence the transport of 14C-thiamin. The results of our experiments show that the transport of 14C-thiamin is specific and energy-dependent and that its properties are significantly changed under the influence of chronic alcoholism. The latter effect occurs by increase in both Umax and Utot, as a manifestation of a compensatory mechanism in thiamin deficiency.

Research paper thumbnail of Olive leaf extract modulates cold restraint stress-induced oxidative changes in rat liver

Journal of the Serbian Chemical Society, 2011

Recently, demonstrated the beneficial effects of different single doses of standardized dry olive... more Recently, demonstrated the beneficial effects of different single doses of standardized dry olive (Olea europaea L.) leaf extract (OLE) in cold restraint stress (CRS)-induced gastric lesions in rats and its influence on oxidative parameters in gastric mucosa were demonstrated. The present study was undertaken to investigate the long-term pretreatment efficacy of OLE and its potential in the modulation of CRS-induced oxidative changes at the liver level. The experimental animals were divided into four groups, i.e., control, OLE-treated, CRS non-treated and CRS treated with OLE (CRS+OLE) groups. CRS caused severe gastric lesions in all non-pretreated animals and two-week pretreatment with OLE (80 mg kg-1 b.w.) attenuated stress-induced gastric lesions significantly. The malondialdehyde (MDA) level as an index of lipid peroxidation, superoxide dismutase (SOD) and catalase (CAT) activities were measured spectrophotometrically in liver tissue homogenates. The MDA level was increased in t...

Research paper thumbnail of Phytochemical analysis and gastroprotective activity of an olive leaf extract

Journal of the Serbian Chemical Society, 2009

Some medicinal features of olive leaf have been known for centuries. It has been traditionally us... more Some medicinal features of olive leaf have been known for centuries. It has been traditionally used as an antimicrobial and to prevent and treat diabetes mellitus and heart disease. Whether olive leaf, a natural antioxidant, influences the gastric defense mechanism and exhibits gastroprotection against experimentally-induced gastric lesions remains unknown. In this study, the content of total phenols, total flavonoids and tannins in olive leaf extract (OLE) were determined. Seven phenolic compounds were identified and quantified (oleuropein, caffeic acid, luteolin, luteolin-7-O-glucoside, apigenin-7-O-glucoside, quercetin, and chryseriol). Furthermore, the protective activity of the OLE in gastric mucosal injury induced by a corrosive concentration of ethanol was investigated. In relation to the control group, pretreatment with OLE (40, 80 and 120 mg kg-1) significantly (p < 0.001) attenuated the gastric lesions induced by absolute ethanol. The protective effect of the OLE was si...

Research paper thumbnail of Transport of 3H L-Alanine Across the Blood-Brain Barrier of in Situ Perfused Guinea Pig Brain

Advances in Behavioral Biology, 1996

Transport of 3H L-alanine through the blood-brain barrier (BBB) was studied using brain vascular ... more Transport of 3H L-alanine through the blood-brain barrier (BBB) was studied using brain vascular perfusion method in guinea pig. Our results indicate that L-alanine passes across the luminal side of the BBB. Unidirectional transport constant Kin ranged from 4.871±0.622 μmin−1g−1 in hippocampus to 5.608±0.902 μmin−1g−1 in parietal cortex, which is comparable with the values obtained for other small neutral non-essential amino acids. Addition of unlabelled L-alanine to perfusing medium caused the decrease in L-alanine transport, indicating the importance of saturable component for L-alanine transport. However, presence of high concentrations of unlabelled L-alanine in perfusing medium (up to 12 mmol/l), did not result in complete inhibition of 3H L-alanine transport through the BBB. Therefore, it seems that another mechanism is also involved in 3H L-alanine transport across the endothelial cells’ luminal membrane. Values for Michaelis-Menten constant for L-alanine transport from blood into brain point out that the affinity of this molecule to its carrier(s) is rather small (Km >1 mmol/1). Capacity of 3H L-alanine blood-to-brain transport is very small as well (Vmax <20 nmol/min/g).

Research paper thumbnail of Transport of endogenous nucleosides in guinea pig heart

The purpose of this study was to investigate the characteristics of transport of endogenous nucle... more The purpose of this study was to investigate the characteristics of transport of endogenous nucleosides into cardiac tissue from coronary circulation. The study was performed on the isolated perfused guinea pig heart, using the rapid paired tracers single-pass technique. The maximal cellular uptake (Umax) and total cellular uptake (Utot) of adenosine, deoxyadenosine, thymidine, uridine, and cytidine were determined. The cellular uptake of adenosine was significantly higher than the cellular uptake of other studied nucleosides. To elucidate the mechanisms of nucleoside transport, competition studies were performed and the influence of S-(p-nitrobenzyl)-6-thioinosine (NBTI) and sodium ion absence on Umax and Utot was investigated. Self- and cross-inhibition studies indicated the saturable mechanism of nucleosides transport into cardiac tissue and the involvement of different transport mechanisms for purine and pyrimidine nucleosides. The study also showed that both equilibrative-sensitive (es) and sodium-dependent transport were responsible for adenosine and thymidine cellular uptake.Key words: nucleosides, transport, heart.

Research paper thumbnail of Effects of sensory-motor cortical lesions on blood-brain permeability in guinea pigs

Metabolic Brain Disease, 1989

Effects of sensory-motor cortical lesions on the function of the blood-brain barrier in distant b... more Effects of sensory-motor cortical lesions on the function of the blood-brain barrier in distant brain areas are poorly understood. Therefore a brain vascular perfusion method has been used to measure simultaneously the kinetics of entry of two inert polar molecules, D-[14C]mannitol (MW 180) and [3H]polyethylene glycol (PEG; MW 4000), into the parietal cortex, hippocampus, and caudate nucleus in guinea pigs with ipsilateral and contralateral sensory-motor cortical lesions. The graphically determined cerebral capillary unidirectional constant, Kin, indicated a marked increase in blood-to-brain transport of both molecules in all regions studied, the changes being significantly higher after contralateral lesion. The mannitol/PEG cerebrovascular permeability constant ratio, Pman/PPEG, suggested the opening up of channels that permit a flow of fluid carrying substances either with respect to (2 days after ipsilateral lesion) or irrespective of their molecular size, depending on the time after lesion. Amphetamine treatment in the guinea pigs with sensory-motor lesions induced more pronounced blood-brain barrier permeability changes for both molecules in distant brain areas.

Research paper thumbnail of Saturable mechanism for delta sleep-inducing peptide (DSIP) at the blood-brain barrier of the vascularly perfused guinea pig brain

Peptides, 1989

Cellular uptake of [125I] labelled DSIP at the luminal interface of the blood-brain barrier (BBB)... more Cellular uptake of [125I] labelled DSIP at the luminal interface of the blood-brain barrier (BBB) was studied in the ipsilateral perfused in situ guinea pig forebrain. Regional unidirectional transfer constants (Kin) calculated from the multiple-time brain uptake analysis were 0.93, 1.33 and 1.66 microliter.min-1 g-1 for the parietal cortex, caudate nucleus and hippocampus, respectively. In the presence of 7 microM unlabelled DSIP the brain uptake of [125I]-DSIP (0.3 nM) was inhibited, the values of Kin being reduced to 0.23-0.38 microliter.min-1 g-1, values that were comparable with the Kin for mannitol. The rapidly equilibrating space of brain, measured from the intercept of the line describing brain uptake versus time on the brain uptake ordinate, Vi, was greater for [125I]-DSIP than for mannitol; in the presence of unlabelled DSIP this was reduced to that of mannitol, and it was suggested that the larger volume for [125I]-DSIP represented binding at specific sites on the brain capillary membrane. L-tryptophan, the N-terminal residue of DSIP, in concentrations of 7 microM and 1 mM, inhibited Kin without affecting Vi. A moderate inhibition of Kin was obtained by vasopressin ([Arg8]-VP), but only at a concentration as high as 0.2 mM. The results suggest the presence of a high affinity saturable mechanism for transport of DSIP across the blood-brain barrier, with subsequent uptake at brain sites that are highly sensitive to L-tryptophan, and may be modulated by [Arg8]-VP.

Research paper thumbnail of Determination of ventilatory threshold based on rating of perceived exertion scale

Srpski arhiv za celokupno lekarstvo, 2004

Research paper thumbnail of Running velocity at the ventilatory threshold and at VO2max, before and after the eight-week cardiovascular endurance training

Medicinski pregled, 2005

The purpose of this research was to compare changes in running velocity at ventilatory threshold ... more The purpose of this research was to compare changes in running velocity at ventilatory threshold with the veliocity at VO2max, before and after the eight-week exercise program. 32 male subjects (age: 22.3 +/- 2.5 years, height: 179.8 +/- 7.6 cm, body mass: 76.8 +/- 9.0 kg) performed a progressive test for ventilatory threshold (VT) measurement and VO2max on treadmill. After 8 weeks of endurance training (3 times per week, 30 to 70 min, in different zones in respect to the ventilatory threshold) the performed the same test. Running velocity at ventilatory threshold increased significantly (p = 0.0001), between initial and final measurements (10.88 +/- 2.09, 12.94 +/- 1.90 km/h, respectively); as well as at VO2max (14.63 +/- 1.86, 16.44 +/- 1.59 km/h, respectively). At the initial test, velocity at ventilatory threshold was 74.11 % of VO2max. At the final test, velocity at ventilatory threshold was 78.43% of VO2max. Running velocity at ventilatory threshold has significantly increased at final test (p = 0.001). Running velocity at ventilatory threshold has significantly increased after eight weeks of endurance training (p = 0.001), when expressed in absolute values and percentage of velocity at VO2max. Comparison between the initial and final test demonstrated a significant increase of observed variables, under experimental conditions: at final test running velocity has increased at ventilatory threshold, in respect to absolute values and expressed as percentage at VO2max.

Research paper thumbnail of Unidirectional uptake of enkephalins at the blood-tissue interface of the blood-cerebrospinal fluid barrier: a saturable mechanism

Regulatory Peptides, 1988

The cellular uptake at the blood-tissue interface of the blood--cerebrospinal fluid (CSF) barrier... more The cellular uptake at the blood-tissue interface of the blood--cerebrospinal fluid (CSF) barrier to tyrosyl-3,5-[3H]enkephalin-[5-L-leucine] (abbreviated to Leu-enkephalin) and of its synthetic analogue o-alanineZ-tyrosyl-3,5-[3H]enkephalin-[5-o-leucine] (abbreviated to o-Alaa-o-LeuS-enkephalin) was studied in the isolated perfused choroid plexuses from the lateral ventricles of the sheep, using the rapid (< 30 s), single circulation, paired-tracer dilution technique, in which o-[~4C]-mannitol serves as an extracellular marker. Cellular uptake of peptides was estimated by directly comparing venous dilution profiles of [3H] and [14C] radioactivities in the absence and presence of unlabelled peptide, the N-terminal amino acid (L-tyrosine), the typical L-transport system substrate, 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH) and the inhibitor of aminopeptidase activity, bacitracin. The cellular uptake of both enkephalins was strongly (65-76%) but not completely inhibited by the addition of 5 mM unlabelled peptide to the bolus; the self-inhibition was significantly higher for o-AlaZ-o-LeuS-enkephalin than for Leu-enkephalin. The addition to the bolus of L-tyrosine (5 mM), BCH (10 mM) or bacitracin (2 mM) reduced the allradioactivity uptake by the choroid plexus of both enkephalins by 20-40%, the degree of inhibition being greater for [aH]-Leu-enkephalin than for its analogue.

Research paper thumbnail of Chronic amphetamine intoxication and the blood-brain barrier permeability to inert polar molecules studied in the vascularly perfused guinea pig brain

Journal of the Neurological Sciences, 1989

The brain vascular perfusion method, with a multiple-time brain uptake analysis, has been employe... more The brain vascular perfusion method, with a multiple-time brain uptake analysis, has been employed to study the effects of chronic amphetamine intoxication on the kinetics of entry of 2 inert polar molecules, D-[14C]mannitol (mol.wt. 180) and [3H]polyethylene glycol (PEG, mol.wt. 4000) into the forebrain of the guinea pig. The unidirectional transfer constants, Kin, determined from graphic analysis 14 and 20 days after chronic amphetamine treatment (5 mg/kg daily, i.p.) showed a marked time-dependent progressive enhancement of transfer for both molecules. The kinetic features of this entry suggest the opening up of pathways through the blood-brain barrier (BBB) which allows mannitol and PEG to pass into the brain at rates which are irrespective of their molecular size and/or lipophilia and these changes cannot be attributed to simple mechanical factors such as hypertension. This opening of the BBB was associated with changes in behaviour (increased locomotor activity, stereotypy, hypervigilance, social withdrawal, and loss of weight) seen in 14-and 20-day amphetamine-treated animals. At 7 and 28 days after the withdrawal of the amphetamine treatment, the behavioural manifestations were absent, and the Kin values for both molecules were not significantly different from those measured in normal control 42 animals which had been treated with placebo injections. The present results suggest a reversible dysfunction of the BBB as a consequence of the chronic amphetamine intoxication which correlates with the behavioural syndrome induced in the guinea pig.

Research paper thumbnail of Measurement of Solute Transport Across the Blood?Brain Barrier in the Perfused Guinea Pig Brain: Method and Application to N-Methyl-?-Aminoisobutyric Acid

Journal of Neurochemistry, 1986

A technique for the vascular perfusion of the guinea pig head in vivo, suitable for measurements ... more A technique for the vascular perfusion of the guinea pig head in vivo, suitable for measurements of blood-to-brain transport under controlled conditions of arterial inflow, has been developed. With a perfusion pressure ranging between 13 and 18 kPa and Pcoz in the arterial inflow of 5 and 5.5 kPd, cerebral blood flow, measured with [I4CJbutanol, was about l ml min-l g-' in the cerebral cortex, hippocampus, and caudate-putamen of the ipsilateral hemisphere; in the cerebellum and pontine white matter it was considerably less, and much higher perfusion pressures were required to establish equal blood flow throughout the whole brain. Regional water content, N a + / K + ratio, ATP, energy charge potential, and lactate content of the ipsilateral side of perfused and nonperfused brain were not significantly different after 10 min perfusion. The ~-[~H]mannitol space did not exceed 1% after 30 min of perfusion, indicating the integrity of the barrier. Over this period, EEG, ECG, and respiratory waveform remained normal. When [14C]N-methyl-a-Guinea pigs were perfused, at 18 kPa, for times increasing from 15 s to 30 min with constant concentrations of [ l4C1MeAIB and ~-[~H]mannitol in the arterial inflow. At the appropriate time the animal was decapitated, the

Research paper thumbnail of Permeability of the Blood-Brain Barrier to the Immunosuppressive Cyclic Peptide Cyclosporin A

Journal of Neurochemistry, 1990

Uptake of the immunosuppressive lipophilic peptide cyclosporin A has been measured by a number of... more Uptake of the immunosuppressive lipophilic peptide cyclosporin A has been measured by a number of techniques. The brain uptake index (BUI) technique in the rat yields only a small BUI value that is not significantly different from that of sucrose and mannitol and is comparable to other published BUI values for this compound. Brain perfusion Abbreviations used: BUI, brain uptake index; CSF, cerebrospinal fluid K,,, unidirectional cerebrosvascular permeability constant; LDL, low density lipoprotein; P., cerebrovascular permeability coefficient;

Research paper thumbnail of Is 28-day follow-up period enough for examining the mortality after resuscitation with human albumin?

Hospital Pharmacology - International Multidisciplinary Journal, 2014

Objective The potential risk of mortality increase due to the use of human albumin (HA) in surgic... more Objective The potential risk of mortality increase due to the use of human albumin (HA) in surgical patients has not been determined yet. The aim of the study was to evaluate the association of mortality rate of surgical patients with other indicators of the quality of health services and consumption of HA and hydroxyethyl starch (HES). Methods The study of a time series at the surgical department analyzed monthly indicators of the quality of health services. The monthly consumption of HA and HES is shown as a number of HA or HES bottles consumed in the intensive care unit (ICU) or outside the ICU. Autoregressive integrated moving average (ARIMA) model was used for the statistical analysis. Results For the total mortality rate, four significantly predictors in moving average model were identified. The total mortality rates for each next month were significantly directly dependent on the unobserved random error from the current and previous month. Number of operated patients showed an indirect effect on the total mortality rate. Number of HA bottles consumed in the ICU, mortality rate of operated patients and patients without operation were directly associated with the increased total mortality rate. Conclusions Follow-up period for examination of the mortality from resuscitation with HA in a heterogeneous surgical population can not be less than two months. ARIMA can be extremely useful in determining a total period of time when all mortality due to the application of certain drug in a particular population will be manifested.

Research paper thumbnail of Penetration of 3H Tiazofurin from Blood into Guinea Pig Brain

Advances in Behavioral Biology, 1996

Transport of tiazofurin (2-β-D-ribofuranosyl thiazole-4-carboxamide) across the blood-brain barri... more Transport of tiazofurin (2-β-D-ribofuranosyl thiazole-4-carboxamide) across the blood-brain barrier (BBB) was studied using brain vascular perfusion method in the guinea pig. The obtained results demonstrate that brain clearance of 3H tiazofurin significantly differs from zero, suggesting that this molecule penetrates from blood into the brain. The values of tiazofurin brain clearance are very close to the values obtained for neuropeptides and other so called “slow penetrating molecules” (regarding the blood brain barrier). Addition of increasing concentrations of unlabelled tiazofurin to the perfusing medium caused a significant decrease in the uptake of [3H] labelled tiazofurin. Therefore, penetration of tiazofurin from blood into brain seems to be a saturable process. Presence of increasing concentrations of unlabelled adenosine has similar effect as the presence of unlabelled tiazofurin in the perfusing medium. However, it did not cause complete inhibition of tiazofurin brain uptake.

Research paper thumbnail of Characteristics of thiamin transport in the isolated perfused guinea pig heart

Archives Of Physiology And Biochemistry, 1993

The cellular uptake of (14C)-thiamin hydrochloride was studied in the isolated perfused guinea pi... more The cellular uptake of (14C)-thiamin hydrochloride was studied in the isolated perfused guinea pig heart, using the rapid single circulation, paired-tracer technique, in which D-(3H)-mannitol serves as an extracellular marker. Cellular uptake of this vitamin was estimated by directly comparing venous dilution profiles of (14C) and (3H) radioactivities in the absence and presence of unlabelled thiamin hydrochloride and pyrithiamin hydrobromide. The maximal cellular uptake (Umax) of thiamin was very low (5.31 +/- 1.79%), while in the presence of 10 mM unlabelled thiamin and 1 mM pyrithiamin, Umax was significantly greater (9.71 +/- 1.57% and 12.30 +/- 0.82%, respectively). Our data suggest that there is a saturable mechanism of sarcolemmal thiamin transport out of myocardial cell, while this transport into the cell is unsaturable.

Research paper thumbnail of Roles of sulfur-containing amino acids in gastrointestinal physiology and pathophysiology

Vojnosanitetski pregled, 2020

Research paper thumbnail of Suppression of methionine-induced colon injury of young rats by cysteine and N-acetyl-L-cysteine

Molecular and cellular biochemistry, Jan 17, 2017

Changes in the methionine metabolism can cause a state called hyperhomocysteinemia, inducing oxid... more Changes in the methionine metabolism can cause a state called hyperhomocysteinemia, inducing oxidative stress in the gut. The production of free radicals is important in the colon damage caused by methionine. This study aimed at evaluating the effect of the use of L-cysteine and N-acetyl-L-cysteine on the colon morphometry of young rats treated with methionine. A total number of 32 male rats were distributed in a randomized experimental design in 4 groups: control group treated with saline; methionine group; cysteine + methionine group, and N-acetyl-L-cysteine + methionine group. After 21 days of treatment, rats were sacrificed and the colon samples were taken for histological and biochemical analysis. Methionine load increased depth of crypts, the lamina muscularis mucosae thickness, the mucosal height, and the number of cells in lamina propria (p < 0.01). Combination of methionine with L-cysteine (C group) and with N-acetyl-L-cysteine (N group) reversed methionine effects. Meth...

Research paper thumbnail of Antioxidant effect of dry olive (Olea europaea L.) leaf extract on ethanol-induced gastric lesions in rats

Mediterranean Journal of Nutrition and Metabolism, 2009

gastric lesions induced. Furthermore, OLE was effective in the prevention of an increase in gastr... more gastric lesions induced. Furthermore, OLE was effective in the prevention of an increase in gastric lipid peroxidation and in the prevention of a decrease in antioxidative enzyme activity. The results obtained indicate that OLE has gastroprotective activity against ethanol-induced gastric lesions in rats, possibly related to its antioxidative properties.

Research paper thumbnail of Attenuation of cold restraint stress-induced gastric lesions by an olive leaf extract

General physiology and biophysics, 2009

Olive leaf extract (OLE) possesses, among other, antioxidative properties, but whether it influen... more Olive leaf extract (OLE) possesses, among other, antioxidative properties, but whether it influences gastroprotection against stress-induced gastric lesions remains unknown. In this study we investigated the protective effect of OLE, a natural antioxidant, on gastric mucosal damage induced by cold restraint stress (CRS) in rats. Three different doses of commercial OLE EFLA((R)) 943 were applied intragastrically (i.g.) 30 min prior to stress induction. Macroscopic gastric lesions were evaluated and ulcer index (UI) was calculated. Histological evidence of gastric mucosal lesions was also obtained. Concentration of malondialdehyde (MDA) as an index of lipid peroxidation, and catalase (CAT) and superoxide dismutase (SOD) activities were determined in gastric mucosa. The effects of applied OLE on gastric mucosal lesions, lipid peroxidation and antioxidative enzymes activity were compared with effects of i.g. pretreatment of reference drug, ranitidine. CRS caused severe gastric lesions i...

Research paper thumbnail of Properties of thiamin transport in isolated perfused hearts of chronically alcoholic guinea pigsThis article is one of a selection of papers published in the special issue Bridging the Gap: Where Progress in Cardiovascular and Neurophysiologic Research Meet

Canadian Journal of Physiology and Pharmacology, 2008

The aim of this study was to determine the mechanism of transport of 14C-thiamin in the hearts of... more The aim of this study was to determine the mechanism of transport of 14C-thiamin in the hearts of healthy (nonalcoholic) and chronically alcoholic guinea pigs. We used the single-pass, paired-tracer dilution method on isolated and retrogradely perfused guinea pig hearts. The maximal cellular uptake (Umax) and total cellular uptake (Utot) of 14C-thiamin were determined under control conditions and under influence of possible modifiers. We tested how the presence of unlabeled thiamin, metabolic inhibitors, or absence of sodium ions influence the transport of 14C-thiamin. The results of our experiments show that the transport of 14C-thiamin is specific and energy-dependent and that its properties are significantly changed under the influence of chronic alcoholism. The latter effect occurs by increase in both Umax and Utot, as a manifestation of a compensatory mechanism in thiamin deficiency.

Research paper thumbnail of Olive leaf extract modulates cold restraint stress-induced oxidative changes in rat liver

Journal of the Serbian Chemical Society, 2011

Recently, demonstrated the beneficial effects of different single doses of standardized dry olive... more Recently, demonstrated the beneficial effects of different single doses of standardized dry olive (Olea europaea L.) leaf extract (OLE) in cold restraint stress (CRS)-induced gastric lesions in rats and its influence on oxidative parameters in gastric mucosa were demonstrated. The present study was undertaken to investigate the long-term pretreatment efficacy of OLE and its potential in the modulation of CRS-induced oxidative changes at the liver level. The experimental animals were divided into four groups, i.e., control, OLE-treated, CRS non-treated and CRS treated with OLE (CRS+OLE) groups. CRS caused severe gastric lesions in all non-pretreated animals and two-week pretreatment with OLE (80 mg kg-1 b.w.) attenuated stress-induced gastric lesions significantly. The malondialdehyde (MDA) level as an index of lipid peroxidation, superoxide dismutase (SOD) and catalase (CAT) activities were measured spectrophotometrically in liver tissue homogenates. The MDA level was increased in t...

Research paper thumbnail of Phytochemical analysis and gastroprotective activity of an olive leaf extract

Journal of the Serbian Chemical Society, 2009

Some medicinal features of olive leaf have been known for centuries. It has been traditionally us... more Some medicinal features of olive leaf have been known for centuries. It has been traditionally used as an antimicrobial and to prevent and treat diabetes mellitus and heart disease. Whether olive leaf, a natural antioxidant, influences the gastric defense mechanism and exhibits gastroprotection against experimentally-induced gastric lesions remains unknown. In this study, the content of total phenols, total flavonoids and tannins in olive leaf extract (OLE) were determined. Seven phenolic compounds were identified and quantified (oleuropein, caffeic acid, luteolin, luteolin-7-O-glucoside, apigenin-7-O-glucoside, quercetin, and chryseriol). Furthermore, the protective activity of the OLE in gastric mucosal injury induced by a corrosive concentration of ethanol was investigated. In relation to the control group, pretreatment with OLE (40, 80 and 120 mg kg-1) significantly (p < 0.001) attenuated the gastric lesions induced by absolute ethanol. The protective effect of the OLE was si...

Research paper thumbnail of Transport of 3H L-Alanine Across the Blood-Brain Barrier of in Situ Perfused Guinea Pig Brain

Advances in Behavioral Biology, 1996

Transport of 3H L-alanine through the blood-brain barrier (BBB) was studied using brain vascular ... more Transport of 3H L-alanine through the blood-brain barrier (BBB) was studied using brain vascular perfusion method in guinea pig. Our results indicate that L-alanine passes across the luminal side of the BBB. Unidirectional transport constant Kin ranged from 4.871±0.622 μmin−1g−1 in hippocampus to 5.608±0.902 μmin−1g−1 in parietal cortex, which is comparable with the values obtained for other small neutral non-essential amino acids. Addition of unlabelled L-alanine to perfusing medium caused the decrease in L-alanine transport, indicating the importance of saturable component for L-alanine transport. However, presence of high concentrations of unlabelled L-alanine in perfusing medium (up to 12 mmol/l), did not result in complete inhibition of 3H L-alanine transport through the BBB. Therefore, it seems that another mechanism is also involved in 3H L-alanine transport across the endothelial cells’ luminal membrane. Values for Michaelis-Menten constant for L-alanine transport from blood into brain point out that the affinity of this molecule to its carrier(s) is rather small (Km >1 mmol/1). Capacity of 3H L-alanine blood-to-brain transport is very small as well (Vmax <20 nmol/min/g).

Research paper thumbnail of Transport of endogenous nucleosides in guinea pig heart

The purpose of this study was to investigate the characteristics of transport of endogenous nucle... more The purpose of this study was to investigate the characteristics of transport of endogenous nucleosides into cardiac tissue from coronary circulation. The study was performed on the isolated perfused guinea pig heart, using the rapid paired tracers single-pass technique. The maximal cellular uptake (Umax) and total cellular uptake (Utot) of adenosine, deoxyadenosine, thymidine, uridine, and cytidine were determined. The cellular uptake of adenosine was significantly higher than the cellular uptake of other studied nucleosides. To elucidate the mechanisms of nucleoside transport, competition studies were performed and the influence of S-(p-nitrobenzyl)-6-thioinosine (NBTI) and sodium ion absence on Umax and Utot was investigated. Self- and cross-inhibition studies indicated the saturable mechanism of nucleosides transport into cardiac tissue and the involvement of different transport mechanisms for purine and pyrimidine nucleosides. The study also showed that both equilibrative-sensitive (es) and sodium-dependent transport were responsible for adenosine and thymidine cellular uptake.Key words: nucleosides, transport, heart.

Research paper thumbnail of Effects of sensory-motor cortical lesions on blood-brain permeability in guinea pigs

Metabolic Brain Disease, 1989

Effects of sensory-motor cortical lesions on the function of the blood-brain barrier in distant b... more Effects of sensory-motor cortical lesions on the function of the blood-brain barrier in distant brain areas are poorly understood. Therefore a brain vascular perfusion method has been used to measure simultaneously the kinetics of entry of two inert polar molecules, D-[14C]mannitol (MW 180) and [3H]polyethylene glycol (PEG; MW 4000), into the parietal cortex, hippocampus, and caudate nucleus in guinea pigs with ipsilateral and contralateral sensory-motor cortical lesions. The graphically determined cerebral capillary unidirectional constant, Kin, indicated a marked increase in blood-to-brain transport of both molecules in all regions studied, the changes being significantly higher after contralateral lesion. The mannitol/PEG cerebrovascular permeability constant ratio, Pman/PPEG, suggested the opening up of channels that permit a flow of fluid carrying substances either with respect to (2 days after ipsilateral lesion) or irrespective of their molecular size, depending on the time after lesion. Amphetamine treatment in the guinea pigs with sensory-motor lesions induced more pronounced blood-brain barrier permeability changes for both molecules in distant brain areas.

Research paper thumbnail of Saturable mechanism for delta sleep-inducing peptide (DSIP) at the blood-brain barrier of the vascularly perfused guinea pig brain

Peptides, 1989

Cellular uptake of [125I] labelled DSIP at the luminal interface of the blood-brain barrier (BBB)... more Cellular uptake of [125I] labelled DSIP at the luminal interface of the blood-brain barrier (BBB) was studied in the ipsilateral perfused in situ guinea pig forebrain. Regional unidirectional transfer constants (Kin) calculated from the multiple-time brain uptake analysis were 0.93, 1.33 and 1.66 microliter.min-1 g-1 for the parietal cortex, caudate nucleus and hippocampus, respectively. In the presence of 7 microM unlabelled DSIP the brain uptake of [125I]-DSIP (0.3 nM) was inhibited, the values of Kin being reduced to 0.23-0.38 microliter.min-1 g-1, values that were comparable with the Kin for mannitol. The rapidly equilibrating space of brain, measured from the intercept of the line describing brain uptake versus time on the brain uptake ordinate, Vi, was greater for [125I]-DSIP than for mannitol; in the presence of unlabelled DSIP this was reduced to that of mannitol, and it was suggested that the larger volume for [125I]-DSIP represented binding at specific sites on the brain capillary membrane. L-tryptophan, the N-terminal residue of DSIP, in concentrations of 7 microM and 1 mM, inhibited Kin without affecting Vi. A moderate inhibition of Kin was obtained by vasopressin ([Arg8]-VP), but only at a concentration as high as 0.2 mM. The results suggest the presence of a high affinity saturable mechanism for transport of DSIP across the blood-brain barrier, with subsequent uptake at brain sites that are highly sensitive to L-tryptophan, and may be modulated by [Arg8]-VP.

Research paper thumbnail of Determination of ventilatory threshold based on rating of perceived exertion scale

Srpski arhiv za celokupno lekarstvo, 2004

Research paper thumbnail of Running velocity at the ventilatory threshold and at VO2max, before and after the eight-week cardiovascular endurance training

Medicinski pregled, 2005

The purpose of this research was to compare changes in running velocity at ventilatory threshold ... more The purpose of this research was to compare changes in running velocity at ventilatory threshold with the veliocity at VO2max, before and after the eight-week exercise program. 32 male subjects (age: 22.3 +/- 2.5 years, height: 179.8 +/- 7.6 cm, body mass: 76.8 +/- 9.0 kg) performed a progressive test for ventilatory threshold (VT) measurement and VO2max on treadmill. After 8 weeks of endurance training (3 times per week, 30 to 70 min, in different zones in respect to the ventilatory threshold) the performed the same test. Running velocity at ventilatory threshold increased significantly (p = 0.0001), between initial and final measurements (10.88 +/- 2.09, 12.94 +/- 1.90 km/h, respectively); as well as at VO2max (14.63 +/- 1.86, 16.44 +/- 1.59 km/h, respectively). At the initial test, velocity at ventilatory threshold was 74.11 % of VO2max. At the final test, velocity at ventilatory threshold was 78.43% of VO2max. Running velocity at ventilatory threshold has significantly increased at final test (p = 0.001). Running velocity at ventilatory threshold has significantly increased after eight weeks of endurance training (p = 0.001), when expressed in absolute values and percentage of velocity at VO2max. Comparison between the initial and final test demonstrated a significant increase of observed variables, under experimental conditions: at final test running velocity has increased at ventilatory threshold, in respect to absolute values and expressed as percentage at VO2max.

Research paper thumbnail of Unidirectional uptake of enkephalins at the blood-tissue interface of the blood-cerebrospinal fluid barrier: a saturable mechanism

Regulatory Peptides, 1988

The cellular uptake at the blood-tissue interface of the blood--cerebrospinal fluid (CSF) barrier... more The cellular uptake at the blood-tissue interface of the blood--cerebrospinal fluid (CSF) barrier to tyrosyl-3,5-[3H]enkephalin-[5-L-leucine] (abbreviated to Leu-enkephalin) and of its synthetic analogue o-alanineZ-tyrosyl-3,5-[3H]enkephalin-[5-o-leucine] (abbreviated to o-Alaa-o-LeuS-enkephalin) was studied in the isolated perfused choroid plexuses from the lateral ventricles of the sheep, using the rapid (< 30 s), single circulation, paired-tracer dilution technique, in which o-[~4C]-mannitol serves as an extracellular marker. Cellular uptake of peptides was estimated by directly comparing venous dilution profiles of [3H] and [14C] radioactivities in the absence and presence of unlabelled peptide, the N-terminal amino acid (L-tyrosine), the typical L-transport system substrate, 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH) and the inhibitor of aminopeptidase activity, bacitracin. The cellular uptake of both enkephalins was strongly (65-76%) but not completely inhibited by the addition of 5 mM unlabelled peptide to the bolus; the self-inhibition was significantly higher for o-AlaZ-o-LeuS-enkephalin than for Leu-enkephalin. The addition to the bolus of L-tyrosine (5 mM), BCH (10 mM) or bacitracin (2 mM) reduced the allradioactivity uptake by the choroid plexus of both enkephalins by 20-40%, the degree of inhibition being greater for [aH]-Leu-enkephalin than for its analogue.

Research paper thumbnail of Chronic amphetamine intoxication and the blood-brain barrier permeability to inert polar molecules studied in the vascularly perfused guinea pig brain

Journal of the Neurological Sciences, 1989

The brain vascular perfusion method, with a multiple-time brain uptake analysis, has been employe... more The brain vascular perfusion method, with a multiple-time brain uptake analysis, has been employed to study the effects of chronic amphetamine intoxication on the kinetics of entry of 2 inert polar molecules, D-[14C]mannitol (mol.wt. 180) and [3H]polyethylene glycol (PEG, mol.wt. 4000) into the forebrain of the guinea pig. The unidirectional transfer constants, Kin, determined from graphic analysis 14 and 20 days after chronic amphetamine treatment (5 mg/kg daily, i.p.) showed a marked time-dependent progressive enhancement of transfer for both molecules. The kinetic features of this entry suggest the opening up of pathways through the blood-brain barrier (BBB) which allows mannitol and PEG to pass into the brain at rates which are irrespective of their molecular size and/or lipophilia and these changes cannot be attributed to simple mechanical factors such as hypertension. This opening of the BBB was associated with changes in behaviour (increased locomotor activity, stereotypy, hypervigilance, social withdrawal, and loss of weight) seen in 14-and 20-day amphetamine-treated animals. At 7 and 28 days after the withdrawal of the amphetamine treatment, the behavioural manifestations were absent, and the Kin values for both molecules were not significantly different from those measured in normal control 42 animals which had been treated with placebo injections. The present results suggest a reversible dysfunction of the BBB as a consequence of the chronic amphetamine intoxication which correlates with the behavioural syndrome induced in the guinea pig.

Research paper thumbnail of Measurement of Solute Transport Across the Blood?Brain Barrier in the Perfused Guinea Pig Brain: Method and Application to N-Methyl-?-Aminoisobutyric Acid

Journal of Neurochemistry, 1986

A technique for the vascular perfusion of the guinea pig head in vivo, suitable for measurements ... more A technique for the vascular perfusion of the guinea pig head in vivo, suitable for measurements of blood-to-brain transport under controlled conditions of arterial inflow, has been developed. With a perfusion pressure ranging between 13 and 18 kPa and Pcoz in the arterial inflow of 5 and 5.5 kPd, cerebral blood flow, measured with [I4CJbutanol, was about l ml min-l g-' in the cerebral cortex, hippocampus, and caudate-putamen of the ipsilateral hemisphere; in the cerebellum and pontine white matter it was considerably less, and much higher perfusion pressures were required to establish equal blood flow throughout the whole brain. Regional water content, N a + / K + ratio, ATP, energy charge potential, and lactate content of the ipsilateral side of perfused and nonperfused brain were not significantly different after 10 min perfusion. The ~-[~H]mannitol space did not exceed 1% after 30 min of perfusion, indicating the integrity of the barrier. Over this period, EEG, ECG, and respiratory waveform remained normal. When [14C]N-methyl-a-Guinea pigs were perfused, at 18 kPa, for times increasing from 15 s to 30 min with constant concentrations of [ l4C1MeAIB and ~-[~H]mannitol in the arterial inflow. At the appropriate time the animal was decapitated, the

Research paper thumbnail of Permeability of the Blood-Brain Barrier to the Immunosuppressive Cyclic Peptide Cyclosporin A

Journal of Neurochemistry, 1990

Uptake of the immunosuppressive lipophilic peptide cyclosporin A has been measured by a number of... more Uptake of the immunosuppressive lipophilic peptide cyclosporin A has been measured by a number of techniques. The brain uptake index (BUI) technique in the rat yields only a small BUI value that is not significantly different from that of sucrose and mannitol and is comparable to other published BUI values for this compound. Brain perfusion Abbreviations used: BUI, brain uptake index; CSF, cerebrospinal fluid K,,, unidirectional cerebrosvascular permeability constant; LDL, low density lipoprotein; P., cerebrovascular permeability coefficient;