Browsing by Author "Dambrova, Maija"
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Item Acute and long-term administration of palmitoylcarnitine induces muscle-specific insulin resistance in mice(2017-09-01) Liepinsh, Edgars; Makrecka-Kuka, Marina; Makarova, Elina; Volska, Kristine; Vilks, Karlis; Sevostjanovs, Eduards; Antone, Unigunde; Kuka, Janis; Vilskersts, Reinis; Lola, Daina; Loza, Einars; Grinberga, Solveiga; Dambrova, Maija; Faculty of PharmacyAcylcarnitine accumulation has been linked to perturbations in energy metabolism pathways. In this study, we demonstrate that long-chain (LC) acylcarnitines are active metabolites involved in the regulation of glucose metabolism in vivo. Single-dose administration of palmitoylcarnitine (PC) in fed mice induced marked insulin insensitivity, decreased glucose uptake in muscles, and elevated blood glucose levels. Increase in the content of LC acylcarnitine induced insulin resistance by impairing Akt phosphorylation at Ser473. The long-term administration of PC using slow-release osmotic minipumps induced marked hyperinsulinemia, insulin resistance, and glucose intolerance, suggesting that the permanent accumulation of LC acylcarnitines can accelerate the progression of insulin resistance. The decrease of acylcarnitine content significantly improved glucose tolerance in a mouse model of diet-induced glucose intolerance. In conclusion, we show that the physiological increase in content of acylcarnitines ensures the transition from a fed to fasted state in order to limit glucose metabolism in the fasted state. In the fed state, the inability of insulin to inhibit LC acylcarnitine production induces disturbances in glucose uptake and metabolism. The reduction of acylcarnitine content could be an effective strategy to improve insulin sensitivity.Item Antidepressive-like Behavior-Related Metabolomic Signatures of Sigma-1 Receptor Knockout Mice(2022-07) Svalbe, Baiba; Zvejniece, Baiba; Stelfa, Gundega; Vilks, Karlis; Vavers, Edijs; Vela, José Miguel; Dambrova, Maija; Zvejniece, Liga; Faculty of PharmacySigma-1 receptor (Sig1R) has been proposed as a therapeutic target for neurological, neu-rodegenerative, and psychiatric disorders, including depression and anxiety. Identifying metabolites that are affected by Sig1R absence and cross-referencing them with specific mood-related behaviors would be helpful for the development of new therapies for Sig1R-associated disorders. Here, we examined metabolic profiles in the blood and brains of male CD-1 background Sig1R knockout (KO) mice in adulthood and old age and correlated them with the assessment of depression-and anxiety-related behaviors. The most pronounced changes in the metabolic profile were observed in the plasma of adult Sig1R KO mice. In adult mice, the absence of Sig1R significantly influenced the amino acid, sphingolipid (sphingomyelin and ceramide (18:1)), and serotonin metabolic pathways. There were higher serotonin levels in plasma and brain tissue and higher histamine levels in the plasma of Sig1R KO mice than in their age-matched wild-type counterparts. This increase correlated with the reduced behavioral despair in the tail suspension test and lack of anhedonia in the sucrose preference test. Overall, these results suggest that Sig1R regulates behavior by altering serotonergic and histaminergic systems and the sphingolipid metabolic pathway.Item Ārstniecības augi latviešu tautas ārstniecības pierakstos un to praktiskā lietojuma analīze. Promocijas darba kopsavilkums(Rīgas Stradiņa universitāte, 2021) Sīle, Inga; Dambrova, Maija; Romāne, EditaDaudzi Eiropas valstīs veiktie etnobotāniskie pētījumi vērš uzmanību uz ārstniecības augu tradicionālās izmantošanas pieaugošo nozīmi. Eiropā zināšanas par ārstniecības augu lietošanu balstās senā vēsturē un tradīcijās. Arī Latvija ir valsts ar gadsimtos krātām tautas medicīnas tradīcijām un plašu šo zināšanu arhīvu. Promocijas darba mērķis bija apkopot un analizēt latviešu tautas ārstniecības pierakstos pieejamās zināšanas par ārstniecības augu lietošanu un meklēt jaunas idejas šo zināšanu praktiskam lietojumam mūsdienās. Promocijas darbs pirmo reizi starptautiskajai zinātniskajai sabiedrībai atklāj latviešu tautas ārstniecības pierakstos iekļauto informāciju par ārstēšanos ar augiem, kas līdz šim nebija tulkota angļu valodā, tāpēc nebija pieejama citu valstu pētniekiem. Pētījums ietver sarakstu ar Latvijas teritorijā 19. gs. beigās un 20. gs. pirmajā pusē tautas medicīnā izmantotiem augiem, to sugām, ārstniecībā lietotām šo augu daļām un pagatavojumiem no tām, to ievadīšanas veidu un slimībām vai to simptomiem, kas ārstēti ar šiem līdzekļiem. Darbs satur informāciju par 211 augu ģintīm, no kurām lielākā daļa tika izmantotas gremošanas un elpošanas sistēmas traucējumu ārstēšanai. Lai saprastu, vai folkloras materiālos norādītā informācija mūsdienās ir aktuāla, tradicionālais augu lietojums tika salīdzināts ar informāciju, balstītu uz pierādījumiem. Pētījumā secināts, ka 59 augu drogām ir pieejamas oficiālas Eiropas Zāļu aģentūras datubāzē publicētas monogrāfijas, bet lielākajai daļai latviešu tautas ārstniecības pierakstos minēto indikāciju nav zinātniska pierādījuma. Pēc sistemātiskas folkloras materiālu analīzes turpmākam pētījumam tika izvēlēti Pelargonium sidoides DC. un Prunus padus L., lai apstiprinātu šo augu drogu tradicionālo lietojumu iekaisuma stāvokļu ārstēšanai. Šim nolūkam pētījuma gaitā tika noskaidroti to pretiekaisuma aktivitātes molekulārie mehānismi. Iegūtie rezultāti sniedz pierādījumu, ka abu augu drogu ekstraktiem in vitro un ex vivo ir izteikta pretiekaisuma aktivitāte, tā apstiprinot to izmantošanas lietderību latviešu tautas medicīnā par efektīvu līdzekli iekaisuma procesu mazināšanai. Promocijas darba rezultātu nozīmīgums: tie var rosināt jaunas idejas turpmākiem ar Latvijas teritorijā augošu augu izmantošanas iespējām saistītiem pētījumiem un var pavērt jaunas perspektīvas gan nacionāliem, gan starptautiskiem etnobotāniskiem pētījumiem.Item Assessment of iodine and selenium nutritional status in women of reproductive age in Latvia(2021-11-05) Veisa, Vija; Kalere, Ieva; Zake, Tatjana; Strele, Ieva; Makrecka, Marina; Upmale-Engela, Sabine; Skesters, Andrejs; Rezeberga, Dace; Lejnieks, Aivars; Pudule, Iveta; Grinberga, Daiga; Velika, Biruta; Dambrova, Maija; Konrade, Ilze; Department of Obstetrics and Gynaecology; Department of Internal Diseases; Institute of Occupational Safety and Environmental Health; Bioķīmijas zinātniskā laboratorijaBackground and Objectives: Adequate dietary intake of iodine and selenium is essential during pregnancy. While iodine is vital for maternal thyroid function and fetal development, selenium contributes to the regulation of thyroid function and thyroid autoimmunity. This study aimed to assess the consumption of iodine-and selenium-containing products by women of reproductive age and the iodine and selenium nutritional status of pregnant women in Latvia. Materials and Methods: Population health survey (2010–2018) data were used to characterize dietary habits in women of reproductive age. Additionally, 129 pregnant women in the first trimester were recruited; they completed a questionnaire and were tested for thyroid function, urinary iodine concentration (UIC), and serum selenium and selenoprotein P levels. Results: The use of some dietary sources of iodine (e.g., milk and dairy products) and selenium (e.g., bread) has decreased in recent years. Less than 10% of respondents reported the use of iodized salt. The use of supplements has become more common (reported by almost 50% of respondents in 2018). Dietary habits were similar in pregnant women, but the use of supplements was even higher (almost 70%). Nevertheless, most supplements used in pregnancy had insufficient contents of iodine and selenium. Thyroid function was euthyreotic in all women, but 13.9% of participants had a thyroid peroxidase antibodies (TPO-ab) level above 60 IU/mL. The median UIC (IQR) was 147.2 (90.0–248.1) µg/gCr, and 52.8% of pregnant women had a UIC below 150 µg/gCr. The mean selenium (SD) level was 101.5 (35.6) µg/L; 30.1% of women had a selenium level below 80 µg/L. The median selenoprotein P level was 6.9 (3.1–9.0) mg/L. Conclusions: Iodine nutrition in Latvian population of pregnant women was near the lower limit of adequate and a third of the population had a selenium deficiency. Supplements were frequently used, but most did not contain the recommended amounts of iodine and selenium.Item Cardioprotective effects of N-hydroxyguanidine PR5 in myocardial ischaemia and reperfusion in rats(1999) Veveris, Maris; Dambrova, Maija; Cirule, Helena; Meirena, Dainuvite; Kalvinsh, Ivars; Wikberg, Jarl E.S.1. The potential for the N-hydroxyguanidine compound PR5 (N-(3,4-dimethoxy-2-chlorobenzylideneamino)-N'-hydroxyguanidine) as a cardioprotective agent in heart ischaemia and reperfusion injury was investigated using rat models. 2. Administration of 1-10 mg kg-1 of PR5 5 min before 10 min of left coronary artery occlusion, followed by 20 min reperfusion, strongly inhibited repel fusion burst of arrhythmias and markedly improved the survival of the animals (e.g. ventricular fibrillation incidence 93 vs 43% (P < 0.05); mortality 47 vs 0% (P < 0.05), for controls and for 3 mg kg-1 of PR5, respectively). 3. Administration of 3 mg kg-1 of PR5 1 min before reperfusion to rats subjected to 10 min occlusion, 20 min reperfusion was most effective in reducing arrhythmias and decreasing mortality (43 vs 0% P < 0.05), but effects were also seen when PR5 was administered 0, 1 and 5 min after start of reperfusion. 4. Coronary occlusion/reperfusion (10-20 min) increased malondialdehyde (MDA) of rat hearts (0.88 ± 0.13 for sham vs 1.45 ± 0.12 nmol mg-1 protein for ischaemic; P < 0.05). In rats where 3 mg kg-1 PR5 were administered 1 min before reperfusion the increase was attenuated (MDA being 1.04 ± 0.12; P < 0.05 vs ischaemic). 5. PR5 caused a substantial reduction of the infarction size in rats subjected to 180 min left coronary artery occlusion, followed by 120 min of reperfusion; the necrotic zone being 326 ± 32 mg for controls vs 137 ± 21 mg for animals treated with 3 x 3 mg kg-1 of PR5 (P < 0.01). 6. PR5 reduced the elevation of the ST-segment of the ECGs, as well as caused pronounced attenuation of the rapid blood pressure drop seen at the start of reperfusion following coronary artery occlusion. 7. We conclude that the N-hydroxyguanidine PR5 provides remarkable protection against ischaemia and reperfusion induced myocardial necrosis and life-threatening arrhythmias. These effects of PR5 are discussed in relation to a recently discovered ability of N-hydroxyguanidines to function as electron accepters at the xanthine oxidase enzyme.Item Carnitine and γ-Butyrobetaine Stimulate Elimination of Meldonium due to Competition for OCTN2-mediated Transport(2017-05-01) Liepinsh, Edgars; Makarova, Elina; Sevostjanovs, Eduards; Hartmane, Dace; Cirule, Helena; Zharkova-Malkova, Olga; Grinberga, Solveiga; Dambrova, Maija; Faculty of PharmacyMeldonium (3-(2,2,2-trimethylhydrazinium)propionate) is the most potent clinically used inhibitor of organic cation transporter 2 (OCTN2). Inhibition of OCTN2 leads to a decrease in carnitine and acylcarnitine contents in tissues and energy metabolism optimization-related cardioprotective effects. The recent inclusion of meldonium in the World Anti-Doping Agency List of Prohibited Substances and Methods has raised questions about the pharmacokinetics of meldonium and its unusually long elimination time. Therefore, in this study, the rate of meldonium washout after the end of the treatment was tested with and without administration of carnitine, γ-butyrobetaine (GBB) and furosemide to evaluate the importance of competition for OCTN2 transport in mice. Here, we show that carnitine and GBB administration during the washout period effectively stimulated the elimination of meldonium. GBB induced a more pronounced effect on meldonium elimination than carnitine due to the higher affinity of GBB for OCTN2. The diuretic effect of furosemide did not significantly affect the elimination of meldonium, carnitine and GBB. In conclusion, the competition of meldonium, carnitine and GBB for OCTN2-mediated transport determines the pharmacokinetic properties of meldonium. Thus, due to their affinity for OCTN2, GBB and carnitine but not furosemide stimulated meldonium elimination. During long-term treatment, OCTN2-mediated transport ensures a high muscle content of meldonium, while tissue clearance depends on relatively slow diffusion, thus resulting in the unusually long complete elimination period of meldonium.Item A cross-sectional survey of urinary iodine status in Latvia(2014) Konrade, Ilze; Neimane, Lolita; Makrecka, Marina; Strele, Ieva; Liepinsh, Edgars; Lejnieks, Aivars; Vevere, Parsla; Gruntmanis, Ugis; Pirags, Valdis; Dambrova, Maija; Rīga Stradiņš UniversityBackground and objective: A nationwide survey of schoolchildren was conducted to detect regional differences in urinary iodine excretion in Latvia and to compare the results with data from the newborn thyroid-stimulating hormone (TSH) screening database as well with the results of a similar study performed in Latvia 10 years ago. Materials and methods: We conducted a cross-sectional school-based cluster survey of 915 children aged 9-12 years in 46 randomly selected schools in all regions of Latvia. Urine samples, questionnaires on the consumption of iodized salt and information on socioeconomic status were collected. TSH levels in newborns were also measured. Results: The median creatinine-standardized urinary iodine concentration (UIC) in our study was 107.3 mg/g Cr. UIC measurements indicative of mild iodine deficiency were present in 31.6%, moderate deficiency in 11.9% and severe deficiency in 2.8% of the participants. The prevalence of iodine deficiency was the highest in the southeastern region of Latgale and the northeastern region of Vidzeme. The prevalence of TSH values >5 mIU/L followed a similar pattern. The self-reported prevalence of regular iodized salt consumption was 10.2%. Children from urban schools had a significantly lower UIC than children from rural schools. Conclusions: Our findings suggest that although the overall median UIC in Latvian schoolchildren falls within the lower normal range, almost 50% of the schoolchildren are iodine deficient, especially in urban schools and in the eastern part of Latvia. The absence of amandatory salt iodization program puts a significant number of children and pregnantwomen at risk.Item The Cultivation of Chelidonium majus L. Increased the Total Alkaloid Content and Cytotoxic Activity Compared with Those of Wild-Grown Plants(2021-09) Krizhanovska, Valerija; Sile, Inga; Kronberga, Arta; Nakurte, Ilva; Mezaka, Ieva; Dambrova, Maija; Pugovics, Osvalds; Grinberga, Solveiga; Department of Applied Pharmacy; Department of Pharmaceutical ChemistryThe effect of cultivation practises on both the phytochemical profile and biological activity of aqueous ethanol extracts of Chelidonium majus L. was studied. Extracts were prepared from aerial parts of the same plant population collected in the wild and grown under organic farming conditions. Both qualitative and quantitative analyses of alkaloids and flavonoid derivatives were performed by LC/MS methods, and the cytotoxicity of lyophilised extracts was studied in B16-F10, HepG2, and CaCo-2 cells. Coptisine was the dominant alkaloid of extracts prepared from wild-grown plants, whereas after cultivation, chelidonine was the most abundant alkaloid. The total alkaloid content was significantly increased by cultivation. Ten flavonol glycoconjugates were identified in C. majus extracts, and quantitative analysis did not reveal significant differences between extracts prepared from wild-grown and cultivated specimens. Treatment with C. majus extracts resulted in a dose-dependent increase in cytotoxicity in all three cell lines. The extracts prepared from cultivated specimens showed higher cytotoxicity than the extracts prepared from wild-grown plants. The strongest cytotoxic effect of cultivated C. majus was observed in B16-F10 cells (IC50 = 174.98 ± 1.12 µg/mL). Cultivation-induced differences in the phytochemical composition of C. majus extracts resulted in significant increases in the cytotoxic activities of the preparations.Item Data on analysis of MK-801 bioavailability in mouse plasma and brain tissue by ultra-performance liquid chromatography-tandem mass spectrometry(2019-12) Svalbe, Baiba; Grinberga, Solveiga; Stelfa, Gundega; Vavers, Edijs; Zvejniece, Baiba; Sevostjanovs, Eduards; Dambrova, Maija; Zvejniece, Liga; Rīga Stradiņš UniversityMK-801, a N-methyl-D-aspartate receptor antagonist, is widely used in animal preclinical experiments to induce memory and learning impairments and schizophrenia-like behavior. In the present study, we compared the plasma and brain tissue concentrations of MK-801 after intraperitoneal (i.p.) or subcutaneous (s.c.) administration at a dose of 0.1 mg/kg in male ICR mice. Moreover, these data present the optimization of ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the analysis of MK-801 in biological samples. Procedures for the preparation of brain tissue and plasma samples and instrumental analysis are described. This article is related to a research article entitled “Effects of the N-methyl-D-aspartate receptor antagonist, MK-801, on spatial memory and influence of the route of administration” [1].Item Data on cardiac and vascular functionality in ex vivo and in vivo models following acute administration of trimethylamine N-oxide(2023-02) Videja, Melita; Vilskersts, Reinis; Sevostjanovs, Eduards; Liepinsh, Edgars; Dambrova, Maija; Faculty of PharmacyThis dataset describes in detail the outcomes of acute trimethylamine N-oxide (TMAO) administration on cardiac, vascular and mitochondrial functionality in ex vivo and in vivo models. The accumulation of TMAO in target tissues was assessed after performing heart perfusion or by incubating aortic tissue in a solution containing TMAO. To evaluate the impact of TMAO on mitochondrial function, the aortic rings and heart homogenates of Wistar rats were incubated in a solution containing [9,10- 3H] palmitate (5 µCi/ml) or D-[U- 14C] glucose (0.625 µCi/ml) in the presence or absence of TMAO with subsequent measurement of substrate oxidation and uptake. The effects of TMAO on the vascular reactivity of isolated conductance and resistance vessels were tested by measuring their response to acetylcholine and sodium nitroprusside. The impact of elevated TMAO levels on cardiac function and infarct size caused by ischemia-reperfusion injury was evaluated in Langendorff perfused heart model. Normal and forced heart functioning was analyzed by echocardiography in CD-1 mouse acute cardiac stress model induced by isoproterenol (10 µg/mouse) upon single and 7 repeated daily administrations of TMAO (120 mg/kg). The data presented in the manuscript provide valuable information on measurements performed under conditions of acutely elevated TMAO levels in experimental models of cardiac and vascular function and energy metabolism. Furthermore, the data have high reuse potential as they could be applied in the planning of future in vitro, ex vivo, and in vivo studies addressing the molecular mechanisms targeted by elevated levels of TMAO.Item Decrease in Long-Chain Acylcarnitine Tissue Content Determines the Duration of and Correlates with the Cardioprotective Effect of Methyl-GBB(2017-08) Kuka, Janis; Makrecka-Kuka, Marina; Cirule, Helena; Grinberga, Solveiga; Sevostjanovs, Eduards; Dambrova, Maija; Liepinsh, Edgars; Faculty of PharmacyIschaemia in the heart is accompanied by the accumulation of long-chain acylcarnitines (LCACs) which is one of the multiple factors that contribute to the ischaemia–reperfusion damage development. Long-term pre-treatment that decreases carnitine and LCAC contents also reduces ischaemia–reperfusion (IR) damage; however, the duration of the post-treatment effects is not known. The aim of the study was to assess the post-treatment effects of the carnitine transport (OCTN2) inhibitor, methyl-GBB, on LCAC content and the duration of its cardioprotective effect. Male Wistar rats received methyl-GBB (5 mg/kg for 28 days), and the anti-infarction effects on Langendorff-perfused hearts and the acylcarnitine profile in cardiac tissues were measured up to 28 days following the end of the treatment. Methyl-GBB pre-treatment for 28 days decreased LCAC heart tissue content by 87%, and the infarct size was decreased by 57%. Fourteen days post-treatment, the LCAC content was still decreased by 69%, and the infarct size was decreased by 32% compared to Control. A significant Pearson correlation (r = 0.48, p = 0.026) was found between infarct size and LCAC tissue content in the methyl-GBB-treated rat hearts. The addition of 2 mM carnitine to isolated heart perfusate significantly diminished the methyl-GBB-induced decrease in LCACs and infarct size. In conclusion, the anti-infarction effect of methyl-GBB continues for at least 2 weeks post-treatment. No less than a 70% decrease in LCAC content is required to protect ischaemic heart tissues, and the decrease in LCAC levels defines the duration of the post-treatment cardioprotective effect of the OCTN2 inhibitor, methyl-GBB.Item Decreased long-chain acylcarnitine content increases mitochondrial coupling efficiency and prevents ischemia-induced brain damage in rats(2023-12) Zvejniece, Liga; Svalbe, Baiba; Vavers, Edijs; Ozola, Melita; Grinberga, Solveiga; Gukalova, Baiba; Sevostjanovs, Eduards; Liepinsh, Edgars; Dambrova, Maija; Department of Pharmaceutical ChemistryLong-chain acylcarnitines (LCACs) are intermediates of fatty acid oxidation and are known to exert detrimental effects on mitochondria. This study aimed to test whether lowering LCAC levels with the anti-ischemia compound 4-[ethyl(dimethyl)ammonio]butanoate (methyl-GBB) protects brain mitochondrial function and improves neurological outcomes after transient middle cerebral artery occlusion (MCAO). The effects of 14 days of pretreatment with methyl-GBB (5 mg/kg, p.o.) on brain acylcarnitine (short-, long- and medium-chain) concentrations and brain mitochondrial function were evaluated in Wistar rats. Additionally, the mitochondrial respiration and reactive oxygen species (ROS) production rates were determined using ex vivo high-resolution fluorespirometry under normal conditions, in models of ischemia-reperfusion injury (reverse electron transfer and anoxia-reoxygenation) and 24 h after MCAO. MCAO model rats underwent vibrissae-evoked forelimb-placing and limb-placing tests to assess neurological function. The infarct volume was measured on day 7 after MCAO using 2,3,5-triphenyltetrazolium chloride (TTC) staining. Treatment with methyl-GBB significantly reduced the LCAC content in brain tissue, which decreased the ROS production rate without affecting the respiration rate, indicating an increase in mitochondrial coupling. Furthermore, methyl-GBB treatment protected brain mitochondria against anoxia–reoxygenation injury. In addition, treatment with methyl-GBB significantly reduced the infarct size and improved neurological outcomes after MCAO. Increased mitochondrial coupling efficiency may be the basis for the neuroprotective effects of methyl-GBB. This study provides evidence that maintaining brain energy metabolism by lowering the levels of LCACs protects against ischemia-induced brain damage in experimental stroke models.Item Decreases in Circulating Concentrations of Long-Chain Acylcarnitines and Free Fatty Acids During the Glucose Tolerance Test Represent Tissue-Specific Insulin Sensitivity(2019) Makarova, Elīna; Makrecka-Kūka, Marina; Vilks, Karlis; Voļska, Kristīne; Sevostjanovs, Eduards; Grinberga, Solveiga; Zarkova-Malkova, Olga; Dambrova, Maija; Liepinsh, Edgars; Faculty of PharmacyBackground: Insulin plays a pivotal role in the regulation of both carbohydrate and lipid intermediate turnover and metabolism. In the transition from a fasted to fed state, insulin action inhibits lipolysis in adipocytes, and acylcarnitine synthesis in the muscles and heart. The aim of this study was to measure free fatty acid (FFA) and acylcarnitine levels during the glucose tolerance test as indicators of tissue-specific insulin resistance. Results: Insulin release in response to glucose administration decreased both FFA and long-chain acylcarnitine levels in plasma in healthy control animals by 30% (120 min). The glucose tolerance test and [3H]-deoxy-D-glucose uptake in tissues revealed that high fat diet-induced lipid overload in C57bl/6N mice evoked only adipose tissue insulin resistance, and plasma levels of FFAs did not decrease after glucose administration. In comparison, db/db mice developed type 2 diabetes with severely impaired insulin sensitivity and up to 70% lower glucose uptake in both adipose tissues and muscles (skeletal muscle and heart), and both plasma concentrations of FFAs and long-chain acylcarnitines did not decrease in response to glucose administration. Conclusions: These results link impaired adipose tissue insulin sensitivity with continuous FFA release in the transition from a fasted to postprandial state, while a blunted decrease in long-chain acylcarnitine levels is associated with muscle and heart insulin resistance.Item Development of local strontium ranelate delivery systems and long term in vitro drug release studies in osteogenic medium(2018-12-01) Loca, Dagnija; Smirnova, Anastasija; Locs, Janis; Dubnika, Arita; Vecstaudza, Jana; Stipniece, Liga; Makarova, Elina; Dambrova, Maija; Faculty of PharmacyIt has been recognized that the operative stabilization of osteoporotic fractures should be followed up with an appropriate osteoporosis treatment in order to decrease the risk of repeated fractures. Despite the good clinical results of strontium ranelate (SrRan) towards the osteoporosis treatment, high drug doses and long treatment period cause an increased risk of serious side effects. Novel local SrRan/poly(lactic acid) (SrRan/PLA) delivery systems containing from 3.57 ± 0.28 wt% to 24.39 ± 0.91 wt% of active substance were developed. In order to resemble the naturally occurring processes, osteogenic media (OM) was used as a release medium for long term (121 days) in vitro drug release studies and UV/VIS method for the determination of SrRan content in OM was developed and validated. Biomimetic calcium phosphate precipitates were found on the surface and in the pores of prepared delivery system after microcapsule exposure to OM for 121 days as well as SrRan particles, indicating that the release of the drug have not been completed within 121 days. In vitro cell viability evaluation approved no cytotoxic effects of microcapsule suspensions and extracts.Item Development of local strontium ranelate delivery systems and long term in vitro drug release studies in osteogenic medium(2018-12-01) Loca, Dagnija; Smirnova, Anastasija; Locs, Janis; Dubnika, Arita; Vecstaudza, Jana; Stipniece, Liga; Makarova, Elina; Dambrova, Maija; Faculty of PharmacyIt has been recognized that the operative stabilization of osteoporotic fractures should be followed up with an appropriate osteoporosis treatment in order to decrease the risk of repeated fractures. Despite the good clinical results of strontium ranelate (SrRan) towards the osteoporosis treatment, high drug doses and long treatment period cause an increased risk of serious side effects. Novel local SrRan/poly(lactic acid) (SrRan/PLA) delivery systems containing from 3.57 ± 0.28 wt% to 24.39 ± 0.91 wt% of active substance were developed. In order to resemble the naturally occurring processes, osteogenic media (OM) was used as a release medium for long term (121 days) in vitro drug release studies and UV/VIS method for the determination of SrRan content in OM was developed and validated. Biomimetic calcium phosphate precipitates were found on the surface and in the pores of prepared delivery system after microcapsule exposure to OM for 121 days as well as SrRan particles, indicating that the release of the drug have not been completed within 121 days. In vitro cell viability evaluation approved no cytotoxic effects of microcapsule suspensions and extracts.Item Dietary polyphenols targeting arterial stiffness : Interplay of contributing mechanisms and gut microbiome-related metabolism(2019-03) De Bruyne, Tess; Steenput, Bieke; Roth, Lynn; De Meyer, Guido R.Y.; Dos Santos, Claudia Nunes; Valentová, Kateřina; Dambrova, Maija; Hermans, NinaIncreased arterial stiffness is a degenerative vascular process, progressing with age that leads to a reduced capability of arteries to expand and contract in response to pressure changes. This progressive degeneration mainly affects the extracellular matrix of elastic arteries and causes loss of vascular elasticity. Recent studies point to significant interference of dietary polyphenols with mechanisms involved in the pathophysiology and progression of arterial stiffness. This review summarizes data from epidemiological and interventional studies on the effect of polyphenols on vascular stiffness as an illustration of current research and addresses possible etiological factors targeted by polyphenols, including pathways of vascular functionality, oxidative status, inflammation, glycation, and autophagy. Effects can either be inflicted directly by the dietary polyphenols or indirectly by metabolites originated from the host or microbial metabolic processes. The composition of the gut microbiome, therefore, determines the resulting metabolome and, as a consequence, the observed activity. On the other hand, polyphenols also influence the intestinal microbial composition, and therefore the metabolites available for interaction with relevant targets. As such, targeting the gut microbiome is another potential treatment option for arterial stiffness.Item Discovery of a Novel Cardioprotective Drug Methyl-GBB: Pharmacological Potential for Lowering Acyl-Carnitines. Doctoral Thesis(Rīga Stradiņš University, 2015) Makrecka-Kūka, Marina; Dambrova, MaijaIschemic heart disease is a major cause of disability and death in millions of people annually. The important pathological consequences of ischemic heart disease arise from impaired cellular energy metabolism. Therefore, a pharmacological intervention that targets cardiac energy metabolism pathways is suggested for the development of novel treatment strategies to improve the clinical outcomes of patients with ischemic heart disease. L-carnitine, a cofactor of acyltransferases, participates in the regulation of mitochondrial energy metabolism. The aim of the thesis was to elucidate the roles of L-carnitine and its metabolites in the regulation of cardiac energy metabolism and to discover novel drug targets to achieve cardioprotection. This thesis describes the importance of glucose and fatty acid energy metabolism pattern in the outcome of cardiac ischemia-reperfusion injury, the role of long-chain acylcarnitines in the regulation of energy metabolism, and the decreasing of the L-carnitine concentration as a strategy to regulate acyl-carnitine availability. The results demonstrate that the long-chain acyl-carnitine concentration determines the energy metabolism pattern in the heart. In addition, the accumulation of long-chain acyl-carnitines impairs glucose metabolism and increases the severity of cardiac ischemia-reperfusion injury. A decrease in acyl-carnitine availability can be achieved by lowering the L-carnitine concentration. The inhibition of both L-carnitine transport via OCTN2 and its biosynthesis via γ-butyrobetaine dioxygenase represent potential stategies for decreasing L-carnitine. The results show that the selective inhibition of L-carnitine transport via OCTN2 compared with the selective inhibition of γ-butyrobetaine dioxygenase is a far more effective approach for decreasing the L-carnitine concentration and inducing cardioprotective effects. A novel cardioprotective agent, Methyl- GBB, a novel inhibitor of γ-butyrobetaine dioxygenase and OCTN2, effectively reduces the concentrations of acyl-carnitines in the heart and mitochondria and limits FA oxidation, thereby stimulating glucose oxidation in heart tissues. Methyl-GBB decreases infarct size and improves survival after myocardial infarction in vivo in rats. This thesis demonstrates that cardioprotection can be achieved by the inhibition of L-carnitine transport via OCTN2, thereby decreasing L-carnitine and acyl-carnitine availability and stimulating glucose metabolism.Item Discovery of a Novel Cardioprotective Drug Methyl-GBB: Pharmacological Potential for Lowering Acyl-Carnitines. Summary of the Doctoral Thesis(Rīga Stradiņš University, 2015) Makrecka-Kūka, Marina; Dambrova, MaijaIschemic heart disease is a major cause of disability and death in millions of people annually. The important pathological consequences of ischemic heart disease arise from impaired cellular energy metabolism. Therefore, a pharmacological intervention that targets cardiac energy metabolism pathways is suggested for the development of novel treatment strategies to improve the clinical outcomes of patients with ischemic heart disease. L-carnitine, a cofactor of acyltransferases, participates in the regulation of mitochondrial energy metabolism. The aim of the thesis was to elucidate the roles of L-carnitine and its metabolites in the regulation of cardiac energy metabolism and to discover novel drug targets to achieve cardioprotection. This thesis describes the importance of glucose and fatty acid energy metabolism pattern in the outcome of cardiac ischemia-reperfusion injury, the role of long-chain acylcarnitines in the regulation of energy metabolism, and the decreasing of the L-carnitine concentration as a strategy to regulate acyl-carnitine availability. The results demonstrate that the long-chain acyl-carnitine concentration determines the energy metabolism pattern in the heart. In addition, the accumulation of long-chain acyl-carnitines impairs glucose metabolism and increases the severity of cardiac ischemia-reperfusion injury. A decrease in acyl-carnitine availability can be achieved by lowering the L-carnitine concentration. The inhibition of both L-carnitine transport via OCTN2 and its biosynthesis via γ-butyrobetaine dioxygenase represent potential stategies for decreasing L-carnitine. The results show that the selective inhibition of L-carnitine transport via OCTN2 compared with the selective inhibition of γ-butyrobetaine dioxygenase is a far more effective approach for decreasing the L-carnitine concentration and inducing cardioprotective effects. A novel cardioprotective agent, Methyl- GBB, a novel inhibitor of γ-butyrobetaine dioxygenase and OCTN2, effectively reduces the concentrations of acyl-carnitines in the heart and mitochondria and limits FA oxidation, thereby stimulating glucose oxidation in heart tissues. Methyl-GBB decreases infarct size and improves survival after myocardial infarction in vivo in rats. This thesis demonstrates that cardioprotection can be achieved by the inhibition of L-carnitine transport via OCTN2, thereby decreasing L-carnitine and acyl-carnitine availability and stimulating glucose metabolism.Item Discovery of E1R: a Novel Positive Allosteric Modulator of Sigma-1 Receptor. Doctoral Thesis(Rīga Stradiņš University, 2017) Vāvers, Edijs; Dambrova, MaijaSigma-1 receptors (Sig1R) ir jauns zāļu mērķis, kurš starptautiskajā receptoru klasifikatorā ir iekļauts tikai 2013. gadā. Tiek uzskatīts, ka Sig1R darbību regulējošie ligandi varētu būt potenciāli zāļu līdzekļi centrālās un perifērās nervu sistēmas saslimšanu ārstēšanai. Promocijas darba mērķis bija pētīt jaunu Sig1R receptora ligandu farmakoloģisko aktivitāti un meklēt praktiskos pielietojumus potenciālai izmantošanai klīnikā. Latvijas Organiskās sintēzes institūtā tika sintezēts jauns savienojums, piracetāma atvasinājums metilfenilpiracetāms. Savienojuma molekulā ir divi hirālie centri, līdz ar to šim savienojumam ir iespējami četri dažādi stereoizomēri: E1R, T1R, E1S, T1S. Veiktais metilfenilpiracetāma aktivitātes skrīnings parādīja, ka savienojums selektīvi modulē Sig1R aktivitāti, bet neietekmē citus pētītos neironālos receptorus un jonu kanālus. Izmantojot selektīvus Sig1R ligandus un kalcija jonu transporta pētījumus šūnu kultūrās, tika pierādīts, ka visi metilfenilpiracetāma enantiomēri spēj pastiprināt selektīvo Sig1R agonistu aktivitāti, tādējādi apliecinot, ka savienojumi darbojas kā pozitīvi allostēriski Sig1R modulatori. Enantiomēri ar R konfigurāciju pie C-4 hirālā centra (E1R, T1R) uzrādīja augstāku bioloģisko aktivitāti par to optiskajiem izomēriem. Ņemot vērā to, ka zināmajiem Sig1R agonistiem piemīt neiroprotektīvas īpašības un tie ir efektīvi dažādas izcelsmes kognitīvo traucējumu ārstēšanā, E1R darbība tika pārbaudīta eksperimentālajos modeļos in vivo. Iegūtie rezultāti liecina, ka E1R spēj ievērojami uzlabot atmiņas procesus, un šo procesu regulācijā ir iesaistīta Sig1R aktivācija, jo selektīvs Sig1R antagonists novērsa E1R efektus. Papildus tam E1R pārsteidzoši uzrādīja arī anti-konvulsīvu efektu, kas ir ievērojami izteiktāks nekā zināmajiem Sig1R agonistiem. Promocijas darba rezultāti ir nozīmīgi, jo līdz šim bez E1R ir zināmi tikai 6 savienojumi, kuri darbojas kā pozitīvi allostēriski Sig1R modulatori, bet E1R ir vienīgais šāda veida savienojums, kuram ir izteikta atmiņas procesus uzlabojoša darbība un neiroprotektīvas īpašības. Promocijas darbs veidots kā rakstu kopa, kas apkopo pētījumu materiālus. Promocijas darbā iegūtie rezultāti ir starptautiski nozīmīgi gan Sig1R receptoru fizioloģiskās lomas pētījumos, gan Sig1R ligandu tālākai virzībai izmantošanai klīniskajā praksē.Item Discovery of E1R: a Novel Positive Allosteric Modulator of Sigma-1 Receptor. Summary of the Doctoral Thesis(Rīga Stradiņš University, 2017) Vāvers, Edijs; Dambrova, MaijaSigma-1 receptors (Sig1R) ir jauns zāļu mērķis, kurš starptautiskajā receptoru klasifikatorā ir iekļauts tikai 2013. gadā. Tiek uzskatīts, ka Sig1R darbību regulējošie ligandi varētu būt potenciāli zāļu līdzekļi centrālās un perifērās nervu sistēmas saslimšanu ārstēšanai. Promocijas darba mērķis bija pētīt jaunu Sig1R receptora ligandu farmakoloģisko aktivitāti un meklēt praktiskos pielietojumus potenciālai izmantošanai klīnikā. Latvijas Organiskās sintēzes institūtā tika sintezēts jauns savienojums, piracetāma atvasinājums metilfenilpiracetāms. Savienojuma molekulā ir divi hirālie centri, līdz ar to šim savienojumam ir iespējami četri dažādi stereoizomēri: E1R, T1R, E1S, T1S. Veiktais metilfenilpiracetāma aktivitātes skrīnings parādīja, ka savienojums selektīvi modulē Sig1R aktivitāti, bet neietekmē citus pētītos neironālos receptorus un jonu kanālus. Izmantojot selektīvus Sig1R ligandus un kalcija jonu transporta pētījumus šūnu kultūrās, tika pierādīts, ka visi metilfenilpiracetāma enantiomēri spēj pastiprināt selektīvo Sig1R agonistu aktivitāti, tādējādi apliecinot, ka savienojumi darbojas kā pozitīvi allostēriski Sig1R modulatori. Enantiomēri ar R konfigurāciju pie C-4 hirālā centra (E1R, T1R) uzrādīja augstāku bioloģisko aktivitāti par to optiskajiem izomēriem. Ņemot vērā to, ka zināmajiem Sig1R agonistiem piemīt neiroprotektīvas īpašības un tie ir efektīvi dažādas izcelsmes kognitīvo traucējumu ārstēšanā, E1R darbība tika pārbaudīta eksperimentālajos modeļos in vivo. Iegūtie rezultāti liecina, ka E1R spēj ievērojami uzlabot atmiņas procesus, un šo procesu regulācijā ir iesaistīta Sig1R aktivācija, jo selektīvs Sig1R antagonists novērsa E1R efektus. Papildus tam E1R pārsteidzoši uzrādīja arī anti-konvulsīvu efektu, kas ir ievērojami izteiktāks nekā zināmajiem Sig1R agonistiem. Promocijas darba rezultāti ir nozīmīgi, jo līdz šim bez E1R ir zināmi tikai 6 savienojumi, kuri darbojas kā pozitīvi allostēriski Sig1R modulatori, bet E1R ir vienīgais šāda veida savienojums, kuram ir izteikta atmiņas procesus uzlabojoša darbība un neiroprotektīvas īpašības. Promocijas darbs veidots kā rakstu kopa, kas apkopo pētījumu materiālus. Promocijas darbā iegūtie rezultāti ir starptautiski nozīmīgi gan Sig1R receptoru fizioloģiskās lomas pētījumos, gan Sig1R ligandu tālākai virzībai izmantošanai klīniskajā praksē.