Research outputs from Pure / Zinātniskās darbības rezultāti no ZDIS Pure

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1,1′-{[3,5-Bis(dodecyloxycarbonyl)-4-(naphthalen-2-yl)-1,4-dihydropyridine-2,6-diyl]bis(methylene)}bis{4-[(E)-2-(naphthalen-2-yl)vinyl]pyridin-1-ium}dibromide
(2022-09) Rucins, Martins; Kaukulis, Martins; Plotniece, Aiva; Pajuste, Karlis; Pikun, Nadiia; Sobolev, Arkadij
Synthesis of a double-charged cationic amphiphilic 1,4-dihydropyridine derivative with dodecyl ester groups at positions 3 and 5 of the 1,4-DHP ring was performed starting from Hantzsch type cyclization of dodecyl acetoacetate, 2-naphthaldehyde and ammonium acetate. Bromination of this compound followed by nucleophilic substitution of bromine with (E)-4-(2-(naphthalen-2-yl)vinyl)pyridine gave the desired cationic amphiphilic 1,1′-{[3,5-bis(dodecyloxycarbonyl)-4-(naph-thalen-2-yl)-1,4-dihydropyridine-2,6-diyl]bis(methylene)}bis{4-[(E)-2-(naphthalen-2-yl)vinyl]pyridin-1-ium}dibromide. The obtained target compound was fully characterized by IR, UV,1 H-NMR,13 C-NMR, HRMS and microanalysis. The characterization of the cationic 1,4-DHP nanoparticles in an aqueous solution was performed by DLS measurements. The obtained results showed that the compound formed nanoparticles with an average diameter of around 300 nm, a PDI value of around 490 and a zeta-potential of around 20 mV for freshly prepared samples. However, after one week of storage at room temperature, an aggregation of nanoparticles was detected.
A 38-year study on Trichinella spp. in wild boar (Sus scrofa) of Latvia shows a stable incidence with an increased parasite biomass in the last decade
(2015-03-01) Kirjušina, Muza; Deksne, Gunita; Marucci, Gianluca; Bakasejevs, Eduards; Jahundoviča, Inese; Daukšte, Anžela; Zdankovska, Aleksandra; Běrziņa, Zanda; Esite, Zanda; Bella, Antonino; Galati, Fabio; Krumiņa, Angelika; Pozio, Edoardo; Department of Infectology
Background: Trichinella spp. are zoonotic parasites transmitted to humans by the consumption of raw or insufficiently cooked meat of different animal species. The most common source of infection for humans is meat from pigs and wild boar (Sus scrofa). The aim of the present work was to evaluate the incidence of Trichinella spp. infections in wild boar hunted in Latvia over a 38 year interval (1976 to 2013). Methods: A total 120,609 wild boars were individually tested for Trichinella spp. by trichinoscopy and, in case of negativity, by artificial digestion of 25 g muscles, in the 1976-2005 period, and by artificial digestion of 25-50 g muscles in the 2006-2013 period. Trichinella spp. larvae were identified at the species level by multiplex PCR. Results: In the study period, the overall prevalence of infected wild boar was 2.5%. Trichinella britovi was the predominant (90%) species. The incidence of Trichinella spp. infection in wild boar exhibited two different trends. From 1976 to 1987, the incidence of infected/hunted wild boar increased from 0.23% to 2.56%, then it decreased to 0.19 in 1994. Thereafter, the incidence fluctuated between 0.05% and 0.37%. A statistically significant (P∈<∈0.05) correlation (r∈=∈0.54; p∈=∈0.0199) was found between the trend of Trichinella spp. incidence in hunted wild boar and the number of snow cover days from 1976 to 1993. From 1997 to 2013, the estimated wild boar population of Latvia increased by 4.9 times and the hunting bag by 9.7 times, with a stable incidence of Trichinella spp. in the population. It follows that the biomass of Trichinella spp. larvae and of T. britovi, in particular, increased. Conclusions: The incidence trends of Trichinella spp. in wild boar could be related to the role played by the snow in reducing the thermal shock and muscle putrefaction which increases the survival of the larvae in muscle tissues of carrion in the 1976-1993 period; and, in the 1997-2013 period, to the increased biomass of Trichinella spp. due to the increased carnivore populations, which are the main reservoirs of these parasites.
ACBM : An Integrated Agent and Constraint Based Modeling Framework for Simulation of Microbial Communities
(2020-12-01) Karimian, Emadoddin; Motamedian, Ehsan
The development of new methods capable of more realistic modeling of microbial communities necessitates that their results be quantitatively comparable with experimental findings. In this research, a new integrated agent and constraint based modeling framework abbreviated ACBM has been proposed that integrates agent-based and constraint-based modeling approaches. ACBM models the cell population in three-dimensional space to predict spatial and temporal dynamics and metabolic interactions. When used to simulate the batch growth of C. beijerinckii and two-species communities of F. prausnitzii and B. adolescent., ACBM improved on predictions made by two previous models. Furthermore, when transcriptomic data were integrated with a metabolic model of E. coli to consider intracellular constraints in the metabolism, ACBM accurately predicted growth rate, half-rate constant, and concentration of biomass, glucose, and acidic products over time. The results also show that the framework was able to predict the metabolism changes in the early stationary compared to the log phase. Finally, ACBM was implemented to estimate starved cells under heterogeneous feeding and it was concluded that a percentage of cells are always subject to starvation in a bioreactor with high volume.
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 Pharmacy
Acylcarnitine 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.
Adapted ECHO-7 virus Rigvir immunotherapy (oncolytic virotherapy) prolongs survival in melanoma patients after surgical excision of the tumour in a retrospective study
(2015-09-18) Doniną, Simona; Strele, Ieva; Proboka, Guna; Auziņš, Jurgis; Alberts, Peteris; Jonsson, Björn; Venskus, Dite; Muceniece, Aina; Institute of Microbiology and Virology; Department of Public Health and Epidemiology
An oncolytic, nonpathogenic ECHO-7 virus adapted for melanoma that has not been genetically modified (Rigvir) is approved and registered for virotherapy, an active and specific immunotherapy, in Latvia since 2004. The present retrospective study was carried out to determine the effectiveness of Rigvir in substage IB, IIA, IIB and IIC melanoma patients on time to progression and overall survival. White patients (N=79) who had undergone surgical excision of the primary melanoma tumour were included in this study. All patients were free from disease after surgery and classified into substages IB, IIA, IIB and IIC. Circulating levels of clinical chemistry parameters were recorded. Survival was analysed by Cox regression. Rigvir significantly (P<0.05) prolonged survival in substage IB-IIC melanoma patients following surgery compared with patients who were under observation (according to current guidelines). The hazard ratio for patients under observation versus treated with Rigvir was statistically significantly different: hazard ratio 6.27 for all, 4.39 for substage IIA-IIB-IIC and 6.57 for substage IIB-IIC patients. The follow-up period was not statistically different between both treatment groups. These results indicate that the patients treated with Rigvir had a 4.39-6.57-fold lower mortality than those under observation. In this study, there was no untoward side effect or discontinuation of Rigvir treatment. Safety assessment of adverse events graded according to NCI CTCAE did not show any value above grade 2 in Rigvir-treated patients. In conclusion, Rigvir significantly prolongs survival in early-stage melanoma patients without any side effect.
Addressing the importance of melanoma tumor-infiltrating lymphocytes in disease progression and clinicopathological characteristics
(2021-12) Zablocka, Tatjana; Nikolajeva, Anna; Kreismane, Madara; Pjanova, Dace; Isajevs, Sergejs
Tumor-infiltrating lymphocytes (TILs) in primary cutaneous melanoma are considered to represent the host's antitumor immunological response; however, whether there are associations between TIL grade and histopathological characteristics and disease survival remains controversial. BRAF mutational status has been established as a routine screening method in advanced malignant melanoma, and worse prognosis rates have been demonstrated in patients harboring BRAF mutations. However, the general impact of BRAF mutational status on survival and histopathological characteristics is still debated. The aim of the present study was to compare the value of the assessment of TIL grade in stages I-II nodular and superficial spreading melanoma and BRAF mutational status, and its influence on clinicopathological characteristics. Altogether, 85 patients at stage IA-IIC who underwent melanoma surgical treatment at the Riga East University Hospital between 2012 and 2017 were retrospectively enrolled in the study. The histopathological characteristics were assessed according to the current World Health Organization and The American Joint Committee on Cancer 8th edition guidelines. The current study showed that patients with melanoma with high TIL grade had significantly better progression-free survival than patients with low TIL grade (hazard ratio, 4.9; 95% CI, 2.3-11.2; P<0.0001). BRAF mutations were observed in 52 patients (61.2%). BRAF mutational status in melanoma was associated with Clark invasion level (P=0.045), patient age (P=0.02) and TIL (P=0.04). The assessment of TIL grade in stage I-II melanoma demonstrated prognostic significance value and may help improve risk assessment in the future.
Adenine auxotrophy - be aware : Some effects of adenine auxotrophy in Saccharomyces cerevisiae strain W303-1A
(2014-08) Kokina, Agnese; Kibilds, Juris; Liepins, Janis
Adenine auxotrophy is a commonly used genetic marker in haploid yeast strains. Strain W303-1A, which carries the ade2-1 mutation, is widely used in physiological and genetic research. Yeast extract-based rich medium contains a low level of adenine, so that adenine is often depleted before glucose. This could affect the cell physiology of adenine auxotrophs grown in rich medium. The aim of our study was to assess the effects of adenine auxotrophy on cell morphology and stress physiology. Our results show that adenine depletion halts cell division, but that culture optical density continues to increase due to cell swelling. Accumulation of trehalose and a coincident 10-fold increase in desiccation stress tolerance is observed in adenine auxotrophs after adenine depletion, when compared to prototrophs. Under adenine starvation, long-term survival of W303-1A is lower than during carbon starvation, but higher than during leucine starvation. We observed drastic adenine-dependent changes in cell stress physiology, suggesting that results may be biased when adenine auxotrophs are grown in rich media without adenine supplementation.
Adhesion and colonisation of microorganisms on porous TiO2 and TiO2-Silver Biomaterials
(2019) Skadiņš, Ingus; Mičko, Lana; Zvaigzne, Liene; Narkevica, I.; Kroiča, Juta; Department of Biology and Microbiology
Alcohol-Induced Alterations in the Vascular Basement Membrane in the Substantia Nigra of the Adult Human Brain
(2022-04) Skuja, Sandra; Jain, Nityanand; Smirnovs, Marks; Murovska, Modra; Joint Laboratory of Electron Microscopy; Institute of Microbiology and Virology
The blood–brain barrier (BBB) represents a highly specialized interface that acts as the first line of defense against toxins. Herein, we investigated the structural and ultrastructural changes in the basement membrane (BM), which is responsible for maintaining the integrity of the BBB, in the context of chronic alcoholism. Human post-mortem tissues from the Substantia Nigra (SN) region were obtained from 44 individuals, then grouped into controls, age-matched alcoholics, and non-age-matched alcoholics and assessed using light and electron microscopy. We found significantly less CD31+ vessels in alcoholic groups compared to controls in both gray and white matter samples. Alcoholics showed increased expression levels of collagen-IV, laminin-111, and fibronectin, which were coupled with a loss of BM integrity in comparison with controls. The BM of the gray matter was found to be more disintegrated than the white matter in alcoholics, as demonstrated by the expression of both collagen-IV and laminin-111, thereby indicating a breakdown in the BM’s structural composition. Furthermore, we observed that the expression of fibronectin was upregulated in the BM of the white matter vasculature in both alcoholic groups compared to controls. Taken together, our findings highlight some sort of aggregation or clumping of BM proteins that occurs in response to chronic alcohol consumption.
Allelic variants of breast cancer susceptibility genes PALB2 and RECQL in the Latvian population
(2019) Hilz, Philip; Heinrihsone, Reičela; Paetzold, Lukas Alexander; Qi, QI; Trofimovičs, Genadijs; Gailīte, Linda; Irmejs, Arvīds; Gardovskis, Jānis; Miklaševičs, Edvīns; Daneberga, Zanda; Onkoloģijas institūts; Department of Surgery; Scientific Laboratory of Molecular Genetics
Analysis of Microorganism Colonization, Biofilm Production, and Antibacterial Susceptibility in Recurrent Tonsillitis and Peritonsillar Abscess Patients
(2022-09) Klagisa, Renata; Racenis, Karlis; Broks, Renars; Balode, Arta Olga; Kise, Ligija; Kroica, Juta; Department of Doctoral Studies; Department of Biology and Microbiology
BACKGROUND: Despite the widespread use of antibiotics to treat infected tonsils, episodes of tonsillitis tend to recur and turn into recurrent tonsillitis (RT) or are complicated by peritonsillar abscesses (PTAs). The treatment of RT and PTAs remains surgical, and tonsillectomies are still relevant. MATERIALS AND METHODS: In a prospective, controlled study, we analyzed the bacteria of the tonsillar crypts of 99 patients with RT and 29 patients with a PTA. We performed the biofilm formation and antibacterial susceptibility testing of strains isolated from study patients. We compared the results obtained between patient groups with the aim to identify any differences that may contribute to ongoing symptoms of RT or that may play a role in developing PTAs. RESULTS: The greatest diversity of microorganisms was found in patients with RT. Gram-positive bacteria were predominant in both groups. Candida species were predominant in patients with a PTA (48.3% of cases). Irrespective of patient group, the most commonly isolated pathogenic bacterium was S. aureus (in 33.3% of RT cases and in 24.14% of PTA cases). The most prevalent Gram-negative bacterium was K. pneumoniae (in 10.1% of RT cases and in 13.4% of PTA cases). At least one biofilm-producing strain was found in 37.4% of RT cases and in 27.6% of PTA cases. Moderate or strong biofilm producers were detected in 16 out of 37 cases of RT and in 2 out of 8 PTA cases. There was a statistically significant association found between the presence of Gram-positive bacteria and a biofilm-formation phenotype in the RT group and PTA group (Pearson χ 2 test, p < 0.001). S. aureus and K. pneumoniae strains were sensitive to commonly used antibiotics. One S. aureus isolate was identified as MRSA. CONCLUSIONS: S. aureus is the most common pathogen isolated from patients with RT, and Candida spp. are the most common pathogens isolated from patients with a PTA. S. aureus isolates are susceptible to most antibiotics. Patients with RT more commonly have biofilm-producing strains, but patients with a PTA more commonly have biofilm non-producer strains. K. pneumoniae does not play a major role in biofilm production.
Analysis of the Spatiotemporal Development of Hematopoietic Stem and Progenitor Cells in the Early Human Embryo
(2019-05-14) Easterbrook, Jennifer; Rybtsov, Stanislav; Gordon-Keylock, Sabrina; Ivanovs, Andrejs; Taoudi, Samir; Anderson, Richard A.; Medvinsky, Alexander
Definitive hematopoietic stem cells (HSCs)first emerge in the aorta-gonad-mesonephros (AGM)region in both mice and humans. An ex vivo culture approach has enabled recapitulation and analysis of murine HSC development. Knowledge of early human HSC development is hampered by scarcity of tissue: analysis of both CFU-C and HSC development in the human embryo is limited. Here, we characterized the spatial distribution and temporal kinetics of CFU-C development within early human embryonic tissues. We then sought to adapt the murine ex vivo culture system to recapitulate human HSC development. We show robust expansion of CFU-Cs and maintenance, but no significant expansion, of human HSCs in culture. Furthermore, we demonstrate that HSCs emerge predominantly in the middle section of the dorsal aorta in our culture system. We conclude that there are important differences between early mouse and human hematopoiesis, which currently hinder the quest to recapitulate human HSC development ex vivo.
Anti-Biofilm Effect of Bacteriophages and Antibiotics against Uropathogenic Escherichia coli
(2022-12) Mukane, Laima; Racenis, Karlis; Rezevska, Dace; Petersons, Aivars; Kroica, Juta; Department of Biology and Microbiology; Department of Internal Diseases
Escherichia coli is a common cause of biofilm-associated urinary tract infections. Bacteria inside the biofilm are more resistant to antibiotics. Six E. coli strains isolated from patients with urinary tract infections were screened for biofilm-forming capability and antimicrobial susceptibility. Two of the most significant biofilm-producing strains were selected for minimal inhibitory concentration and minimal biofilm eradication concentration in vitro testing using amoxicillin-clavulanic acid, ciprofloxacin, and three commercial bacteriophage cocktails (Pyobacteriophag, Ses, and Intesti). In case of a low phage effect, an adaptation procedure was performed. Although the biofilms formed by strain 021UR were resistant to amoxicillin-clavulanic acid and ciprofloxacin, the three phage cocktails were able to reduce biofilm formation. In contrast, phages did not affect the 01206UR strain against planktonic and biofilm-forming cells. After Pyobacteriophag adaptation, the effect improved, and, regardless of the concentration, the adapted phage cocktail could destroy both planktonic cells and the biofilm of strain 01206UR. Bacteriophages capable of killing bacteria in biofilms can be used as an alternative to antibiotics. However, each case should be considered individually due to the lack of clinical trials for phage therapy. Antimicrobial and phage susceptibility should be determined in biofilm models before treatment to achieve the desired anti-biofilm effect.
Anti-Inflammatory, Anti-Bacterial, and Anti-Fungal Activity of Oligomeric Proanthocyanidins and Extracts Obtained from Lignocellulosic Agricultural Waste
(2023-01-15) Andersone, Anna; Janceva, Sarmite; Lauberte, Līga; Ramata-Stunda, Anna; Nikolajeva, Vizma; Zaharova, Natalija; Rieksts, Gints; Telesheva, Galina; Laboratory of Finished Dosage Forms
It has now been proven that many pathogens that cause infections and inflammation gradually mutate and become resistant to antibiotics. Chemically synthesized drugs treating inflammation most often only affect symptoms, but side effects could lead to the failure of human organs’ functionality. On the other hand, plant-derived natural compounds have a long-term healing effect. It was shown that sea buckthorn (SBT) twigs are a rich source of biologically active compounds, including oligomeric proanthocyanidins (PACs). This study aimed to assess the anti-pathogenic and anti-inflammatory activity of water/ethanol extracts and PACs obtained from the lignocellulosic biomass of eight SBT cultivars. The anti-pathogenic activity of extracts and PACs was studied against pathogenic bacteria Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Bacillus cereus and fungus Candida albicans in 96-well plates by the two-fold serial broth microdilution method. The anti-bacterial activity of purified PACs was 4 and 10 times higher than for water and water/ethanol extracts, respectively, but the extracts had higher anti-fungal activity. Purified PACs showed the ability to reduce IL-8 and IL-6 secretion from poly-I:C-stimulated peripheral blood mononuclear cells. For the extracts and PACs of SBT cultivar ‘Maria Bruvele’ in the concentration range 0.0313–4.0 mg/mL, no toxic effect was observed.
Antibacterial Activity of Tanacetum vulgare L. Extracts against Clinical Isolates of Bovine Mastitis
(2023-03) Šukele, Renāte; Bārzdiņa, Ance; Koka, Rudīte; Skadins, Ingus; Lauberte, Līga; Brangule, Agnese; Kovalcuka, Liga; Bandere, Dace; Department of Pharmaceutical Chemistry; Red Cross Medical College of Rīga Stradiņš University; Department of Biology and Microbiology; Laboratory of Finished Dosage Forms
A bovine mastitis is an infectious disease, which is usually treated with antibiotics. Alternatively, herbal medicine has been proposed due to bacterial resistance. The aim of this study was to determine the antibacterial activity of the acetonic and ethanolic extracts of dried flowers and leaves of Tanacetum vulgare L. against bovine mastitis-inducing clinical isolates such as Escherichia coli, Streptococcus agalactiae, Streptococcus uberis, Serratia liquefaciens, Staphylococcus aureus, and reference cultures of S. aureus and E. coli. The extracts of T. vulgare showed partial antibacterial activity against tested strains of S. aureus. The MIC and MBC values of a 70% ethanol extract of flowers (MIC = 3.4 mg/mL, MBC = 3.4–6.8 mg/mL) were lower than for the 70% ethanol extract of leaves (MIC = 15.7–31.4 mg/mL, MBC = 62.9–125.9 mg/mL). The flower extracts showed low activity against E. coli (MIC = 53.9 mg/mL, MBC = 53.9–107.8 mg/mL) and S. agalactiae (MIC, MBC = 53.9 mg/mL). T. vulgare leaf extracts had minimal antibacterial effects against Streptococcus strains (MIC = 31.4–62.9 mg/mL, MBC = 53.9–125.9 mg/mL) and Serratia liquefaciens (MIC, MBC = 125.9 mg/mL). However, flower extracts had a higher phenolic content that did not correlate with antibacterial effects. T. vulgare flower and leaf extracts could be combined to obtain broader antibacterial effects.
Antibacterial Efficiency of Hydroxyapatite Biomaterials with Biodegradable Polylactic Acid and Polycaprolactone Polymers Saturated with Antibiotics
(2016-08-01) Kroiča, Juta; Skadiņš, Ingus; Salma, Ilze; Reinis, Aigars; Sokolova, Marina; Rostoka, Dagnija; Berza, Natalija; Department of Biology and Microbiology
Infections continue to spread in all fields of medicine, and especially in the field of implant biomaterial surgery, and not only during the surgery, but also after surgery. Reducing the adhesion of bacteria could decrease the possibility of biomaterial-associated infections. Bacterial adhesion could be reduced by local antibiotic release from the biomaterial. In this in vitro study, hydroxyapatite biomaterials with antibiotics and biodegradable polymers were tested for their ability to reduce bacteria adhesion and biofilm development. This study examined the antibacterial efficiency of hydroxyapatite biomaterials with antibiotics and biodegradable polymers against Staphylococcus epidermidis and Pseudomonas aeruginosa. The study found that hydroxyapatite biomaterials with antibiotics and biodegradable polymers show longer antibacterial properties than hydroxyapatite biomaterials with antibiotics against both bacterial cultures. Therefore, the results of this study demonstrated that biomaterials that are coated with biodegradable polymers release antibiotics from biomaterial samples for a longer period of time and may be useful for reducing bacterial adhesion on orthopedic implants.
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 Pharmacy
Sigma-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.
Antimicrobial and Antibiofilm Properties of Latvian Honey against Causative Agents of Wound Infections
(2023-04-26) Skadiņš, Ingus; Labsvārds, Krišs Dāvids; Grava, Andra; Amirian, Jhaleh; Tomsone, Laura Elīna; Ruško, Jānis; Viksna, Arturs; Bandere, Dace; Brangule, Agnese; Department of Biology and Microbiology; Department of Pharmaceutical Chemistry
Honey is widely used in traditional medicine and modern wound healing biomaterial research as a broad-spectrum antimicrobial, anti-inflammatory and antioxidant agent. The study’s objectives were to evaluate the antibacterial activity and polyphenolic profiles of 40 monofloral honey samples collected from beekeepers in the territory of Latvia. The antimicrobial and antifungal activity of Latvian honey samples were compared with commercial Manuka honey and the honey analogue sugar solutions–carbohydrate mixture and tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, clinical isolates Extended-Spectrum Beta-Lactamases produced Escherichia coli, Methicillin-resistant Staphylococcus aureus and Candida albicans. Antimicrobial activity was evaluated with the well-diffusion method (80% honey solution w/v) and microdilution method. The honey samples with the highest antimicrobial potential were tested to prevent biofilm development and activity against a preformed biofilm. The principal component analysis of the antimicrobial properties of honey samples vs. polyphenolic profile was performed. Eleven honey samples exhibited antibacterial activity to all investigated bacteria. The antibacterial effect of the samples was most significant on the Gram-positive bacteria compared to the studied Gram-negative bacteria. Latvian honey presents promising potential for use in wound healing biomaterials, opening the possibility of achieving long-term antibacterial effects.
The Antioxidant Activity of Wild-Growing Plants Containing Phenolic Compounds in Latvia
(2023-12) Teterovska, Renāte; Sīle, Inga; Paulausks, Artūrs; Kovalcuka, Liga; Koka, Rudīte; Mauriņa, Baiba; Bandere, Dace; Department of Pharmaceutical Chemistry; Red Cross Medical College of Rīga Stradiņš University; Department of Applied Pharmacy; Laboratory of Finished Dosage Forms; Department of Biology and Microbiology
Ethnobotanical reports from Latvia show that Tanacetum vulgare, Calluna vulgaris, Quercus robur, Artemisa absinthium, and Artemisia vulgaris contain phenolic compounds that have antioxidant properties, which can be beneficial in the treatment and prophylaxis of many diseases. The aim of this study was to characterize the phenolic compounds and antioxidant properties of these plants. Plant extracts were prepared using ethanol or acetone and then freeze-dried. Their total phenolic content (TPC), total flavonoid content (TFC), and total tannin content (TTC) were determined and characterized by HPLC. Their antioxidant properties were determined using a DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay. C. vulgaris herb and T. vulgare leaf extracts contained the highest amounts of flavonoids, but the bark of Q. robur had mostly tannins and phenolic acids. A. absinthium and A. vulgaris had the lowest amounts of polyphenols. When compared using extraction solvents, all acetone extracts had more TPC, more TFC, and better antioxidant activity. All plants contained chlorogenic acid, which contributes to antioxidant properties. The analysed plant extracts could be used in future studies to develop medicinal products with antioxidant properties.
Antioxidant effects of Camellia sinensis L. Extract in patients with type 2 diabetes
(2014-12-01) Spadiene, Asta; Savickiene, Nijole; Ivanauskas, Liudas; Jakstas, Valdas; Skesters, Andrejs; Silova, Alise; Rodovicius, Hiliaras; Bioķīmijas zinātniskā laboratorija
The prevalence of diabetes mellitus (DM) has dramatically increased in the past decade. Furthermore, increasing evidence from research shows that oxidative stress (OS) plays a crucial role in the pathogenesis of diabetes and in its complications. A search for ways to reduce oxidative damage has become the focus of interest for the majority of scientists. In this study, we determined the radical scavenging activity of single green tea constituents by using an on-line high performance liquid chromatography (HPLC)-2,2-diphenyl-1-picrylhydrazyl (DPPH) method and evaluated the antioxidant effects on type 2 diabetic patients by performing a double-blind, placebo-controlled study. Epigallocatechin gallate was identified as the most potent antioxidant, contributing approximately 50% of the total antioxidant capacity of green tea extract. We also found a statistically significant decrement of lipid peroxidation markers in patients treated with green tea extract after 9 months or after 18 months of follow-up. Overall, these findings are attractive for diabetic patients, helping them to keep a high level of performance and well-being, which ultimately may delay the time of disability and reduce mortality.

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