2025. gadā aizstāvētie promocijas darbi un kopsavilkumi

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Antibacterial activity against bovine mastitis-inducing pathogens and antiradical activity of polyphenolic-compounds-containing plant extracts. Doctoral Thesis
(Rīga Stradiņš University, 2025) Teterovska (Šukele), Renāte; Bandere, Dace; Koka, Rudīte
Bovine mastitis is an infectious disease of the cow’s udder, which is usually treated with antibiotics. The overuse and misuse of antibiotics has led to the widespread development of bacterial resistance. Restrictions on the use of antibiotics create a need for alternative treatments and prophylactic measures to reduce the incidence and spread of mastitis. Antioxidant properties of plants – ability to scavenge free radicals, help animals recover and heal faster. Herbal medicine has been used traditionally by farmers for centuries to treat infectious and chronic diseases. However, there is little scientific evidence on the veterinary use of plant extracts. The Thesis aims to provide information on the use of plant extracts against bovine mastitis pathogens, their antiradical activity and to characterise their polyphenolic content. The dried plant material was extracted with 30 %, 50 %, 70 % ethanol and acetone and then freeze-dried for further analysis. The total phenolic, flavonoid, and tannin contents were determined by spectroscopic methods. Fourier transform infrared spectroscopy and high-performance liquid chromatography were used to characterise the chemical composition of the extracts. Clinical isolates inducing bovine mastitis (Escherichia coli, Streptococcus agalactiae, Streptococcus uberis, Serratia liquefaciens, Staphylococcus aureus) and reference cultures of S. aureus and E. coli were used for antibacterial tests. All extracts were screened for their antibacterial activity using a disc diffusion test, and the minimum inhibitory concentration and the minimum bactericidal concentration were determined for the most effective extracts. The antiradical activity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The type of solvent affected the amount of phenolics extracted and the pharmacological effects of the extracts. The plants contained comparable amounts of tannins, which are not often reported in studies but have pharmacological activities. The acetone extracts had a higher total phenolic content and a higher total flavonoid content. All the plant extracts analysed were effective against S. aureus, but the effect against other bovine mastitis pathogens varied by the type of extract used. The types of phenolic compounds present in these plant extracts have a significant impact on the antioxidant activity. The bark of Q. robur and the herbs of C. vulgaris, and the flower and leaf of T. vulgare had good antioxidant and antibacterial potential. Plant extracts have promising pharmacological effects in vitro for the development of a product for bovine mastitis.
Antibacterial activity against bovine mastitis-inducing pathogens and antiradical activity of polyphenolic-compounds-containing plant extracts. Summary of the Doctoral Thesis
(Rīga Stradiņš University, 2025) Teterovska (Šukele), Renāte; Bandere, Dace; Koka, Rudīte
Bovine mastitis is an infectious disease of the cow’s udder, which is usually treated with antibiotics. The overuse and misuse of antibiotics has led to the widespread development of bacterial resistance. Restrictions on the use of antibiotics create a need for alternative treatments and prophylactic measures to reduce the incidence and spread of mastitis. Antioxidant properties of plants – ability to scavenge free radicals, help animals recover and heal faster. Herbal medicine has been used traditionally by farmers for centuries to treat infectious and chronic diseases. However, there is little scientific evidence on the veterinary use of plant extracts. The Thesis aims to provide information on the use of plant extracts against bovine mastitis pathogens, their antiradical activity and to characterise their polyphenolic content. The dried plant material was extracted with 30 %, 50 %, 70 % ethanol and acetone and then freeze-dried for further analysis. The total phenolic, flavonoid, and tannin contents were determined by spectroscopic methods. Fourier transform infrared spectroscopy and high-performance liquid chromatography were used to characterise the chemical composition of the extracts. Clinical isolates inducing bovine mastitis (Escherichia coli, Streptococcus agalactiae, Streptococcus uberis, Serratia liquefaciens, Staphylococcus aureus) and reference cultures of S. aureus and E. coli were used for antibacterial tests. All extracts were screened for their antibacterial activity using a disc diffusion test, and the minimum inhibitory concentration and the minimum bactericidal concentration were determined for the most effective extracts. The antiradical activity was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The type of solvent affected the amount of phenolics extracted and the pharmacological effects of the extracts. The plants contained comparable amounts of tannins, which are not often reported in studies but have pharmacological activities. The acetone extracts had a higher total phenolic content and a higher total flavonoid content. All the plant extracts analysed were effective against S. aureus, but the effect against other bovine mastitis pathogens varied by the type of extract used. The types of phenolic compounds present in these plant extracts have a significant impact on the antioxidant activity. The bark of Q. robur and the herbs of C. vulgaris, and the flower and leaf of T. vulgare had good antioxidant and antibacterial potential. Plant extracts have promising pharmacological effects in vitro for the development of a product for bovine mastitis.
Application of Mycobacterium tuberculosis whole-genome sequencing to address epidemiologically and clinically relevant issues and improve tuberculosis control strategies. Doctoral Thesis
(Rīga Stradiņš University, 2025) Sadovska, Darja; Ranka, Renāte; Bandere, Dace
Despite significant advancements in tuberculosis (TB) diagnostics, treatment, and prevention, the disease remains a major global public health challenge, with only limited reductions in incidence rates observed. In recent years, whole-genome sequencing (WGS) of Mycobacterium tuberculosis isolates has become a key approach for studying various aspects of TB, providing high-resolution insights into strain phylogenetic diversity, drug resistance mechanisms, disease transmission dynamics, and recurrence causes. Although WGS offers a promising alternative to widely implemented molecular and culture-based M. tuberculosis analysis methods, further improvements in sequencing data analysis strategies are needed to fully unlock its potential for addressing critical scientific, epidemiological, and clinical challenges in TB control. This doctoral thesis aimed to apply WGS to M. tuberculosis isolates from Latvian patients to address unresolved epidemiologically and clinically relevant issues impacting TB control and propose improvements for current WGS data analysis strategies. This research focused on two key subsets of patients with TB: those who experienced recurrent TB episodes and those suspected of being part of the same TB clusters based on epidemiological data and conventional genotyping results. The studied population included adults and children with pulmonary or extrapulmonary TB. M. tuberculosis isolates were subjected to WGS for genetic-variant-based strain genotyping, phylogenetic analyses, determination of the causes of recurrent TB episodes, identification of epidemiologically relevant TB clusters, delineation of transmission chains, detection of mixed-strain infections, and WGS-based drug susceptibility testing (DST). Relevant clinical and epidemiological data and results from previous M. tuberculosis isolate analyses were retrieved from patients’ medical records. Conventional genotyping (spoligotyping and insertion sequence 6110 restriction fragment length polymorphism analysis) and phenotypic DST results were compared with WGS findings. Patients’ diagnoses, sputum smear microscopy results, specimen collection timelines, contact tracing and geospatial data were integrated to interpret the WGS results according to the analysis objective. WGS-assigned lineages and sub-lineages generally agreed with the spoligotyping results of the M. tuberculosis isolates studied, with both methods revealing significant variability in M. tuberculosis genotypes in Latvia, even within specific TB patient subsets. The isolates within the two most prevalent M. tuberculosis genotype families in Latvia, Beijing and LAM, exhibited greater genetic relatedness than isolates from other genotype families, with varying drug resistance distribution frequencies observed among different M. tuberculosis spoligotypes. Distinguishing between the two possible causes of TB recurrence (endogenous reactivation and exogenous reinfection) was more precise when performed as a part of the TB cluster transmission chain delineation. This approach integrated WGS data with relevant clinical and epidemiological information, as identifying pairwise single nucleotide variant (SNV) distances and analysing differing SNVs between isolates proved insufficient. Using genetic distance thresholds of 12 SNVs for identifying epidemiologically relevant TB clusters and 5 SNVs for inferring recent transmission events proved effective in a low-to-moderate TB incidence setting. However, the close genetic relatedness of isolates belonging to Beijing and LAM genotype families, which are highly prevalent in Latvia, should be considered during TB cluster identification to avoid the risk of false clustering. Limitations in TB transmission chain delineation included unidentified active TB cases, variability in M. tuberculosis mutation rate, low genetic variability of the pathogen, and tight specimen collection timeline of genetically identical isolates. The proposed integrated approach significantly complemented epidemiological investigation and conventional genotyping results, enabling more accurate identification of source cases and evaluation of index cases. However, its application may not be necessary for all epidemiologically relevant cases. Lastly, discordances between phenotypic and WGS-based DST among the studied isolates were attributed to the technical complexities of phenotypic tests, the variable effects of genetic variants on the minimal inhibitory concentration of drugs, and insufficient data on drug-resistance-conferring variants. While WGS-based DST cannot fully replace pDST, combining these methods provides the most accurate assessment of drug resistance patterns. To conclude, this research provided valuable insights into the TB transmission dynamics in Latvia, the genetic diversity of M. tuberculosis genotypes circulating in the country, and the distribution of drug-resistance-conferring variants among these genotypes. It also highlighted challenges in phenotypic and WGS-based DST, evaluated different WGS-based strategies for determining the causes of recurrent TB, and proposed an integrative approach for delineating TB transmission chains. These findings support the potential of integrating WGS into routine practice as part of a comprehensive local TB surveillance program.
Application of Mycobacterium tuberculosis whole-genome sequencing to address epidemiologically and clinically relevant issues and improve tuberculosis control strategies. Summary of the Doctoral Thesis
(Rīga Stradiņš University, 2025) Sadovska, Darja; Ranka, Renāte; Bandere, Dace
Despite significant advancements in tuberculosis (TB) diagnostics, treatment, and prevention, the disease remains a major global public health challenge, with only limited reductions in incidence rates observed. In recent years, whole-genome sequencing (WGS) of Mycobacterium tuberculosis isolates has become a key approach for studying various aspects of TB, providing high-resolution insights into strain phylogenetic diversity, drug resistance mechanisms, disease transmission dynamics, and recurrence causes. Although WGS offers a promising alternative to widely implemented molecular and culture-based M. tuberculosis analysis methods, further improvements in sequencing data analysis strategies are needed to fully unlock its potential for addressing critical scientific, epidemiological, and clinical challenges in TB control. This doctoral thesis aimed to apply WGS to M. tuberculosis isolates from Latvian patients to address unresolved epidemiologically and clinically relevant issues impacting TB control and propose improvements for current WGS data analysis strategies. This research focused on two key subsets of patients with TB: those who experienced recurrent TB episodes and those suspected of being part of the same TB clusters based on epidemiological data and conventional genotyping results. The studied population included adults and children with pulmonary or extrapulmonary TB. M. tuberculosis isolates were subjected to WGS for genetic-variant-based strain genotyping, phylogenetic analyses, determination of the causes of recurrent TB episodes, identification of epidemiologically relevant TB clusters, delineation of transmission chains, detection of mixed-strain infections, and WGS-based drug susceptibility testing (DST). Relevant clinical and epidemiological data and results from previous M. tuberculosis isolate analyses were retrieved from patients’ medical records. Conventional genotyping (spoligotyping and insertion sequence 6110 restriction fragment length polymorphism analysis) and phenotypic DST results were compared with WGS findings. Patients’ diagnoses, sputum smear microscopy results, specimen collection timelines, contact tracing and geospatial data were integrated to interpret the WGS results according to the analysis objective. WGS-assigned lineages and sub-lineages generally agreed with the spoligotyping results of the M. tuberculosis isolates studied, with both methods revealing significant variability in M. tuberculosis genotypes in Latvia, even within specific TB patient subsets. The isolates within the two most prevalent M. tuberculosis genotype families in Latvia, Beijing and LAM, exhibited greater genetic relatedness than isolates from other genotype families, with varying drug resistance distribution frequencies observed among different M. tuberculosis spoligotypes. Distinguishing between the two possible causes of TB recurrence (endogenous reactivation and exogenous reinfection) was more precise when performed as a part of the TB cluster transmission chain delineation. This approach integrated WGS data with relevant clinical and epidemiological information, as identifying pairwise single nucleotide variant (SNV) distances and analysing differing SNVs between isolates proved insufficient. Using genetic distance thresholds of 12 SNVs for identifying epidemiologically relevant TB clusters and 5 SNVs for inferring recent transmission events proved effective in a low-to-moderate TB incidence setting. However, the close genetic relatedness of isolates belonging to Beijing and LAM genotype families, which are highly prevalent in Latvia, should be considered during TB cluster identification to avoid the risk of false clustering. Limitations in TB transmission chain delineation included unidentified active TB cases, variability in M. tuberculosis mutation rate, low genetic variability of the pathogen, and tight specimen collection timeline of genetically identical isolates. The proposed integrated approach significantly complemented epidemiological investigation and conventional genotyping results, enabling more accurate identification of source cases and evaluation of index cases. However, its application may not be necessary for all epidemiologically relevant cases. Lastly, discordances between phenotypic and WGS-based DST among the studied isolates were attributed to the technical complexities of phenotypic tests, the variable effects of genetic variants on the minimal inhibitory concentration of drugs, and insufficient data on drug-resistance-conferring variants. While WGS-based DST cannot fully replace pDST, combining these methods provides the most accurate assessment of drug resistance patterns. To conclude, this research provided valuable insights into the TB transmission dynamics in Latvia, the genetic diversity of M. tuberculosis genotypes circulating in the country, and the distribution of drug-resistance-conferring variants among these genotypes. It also highlighted challenges in phenotypic and WGS-based DST, evaluated different WGS-based strategies for determining the causes of recurrent TB, and proposed an integrative approach for delineating TB transmission chains. These findings support the potential of integrating WGS into routine practice as part of a comprehensive local TB surveillance program.
Mycobacterium tuberculosis pilna genoma sekvencēšanas lietojums epidemioloģiski un klīniski nozīmīgu jautājumu risinājumiem un tuberkulozes kontroles stratēģiju uzlabošanai. Promocijas darba kopsavilkums
(Rīgas Stradiņa universitāte, 2025) Sadovska, Darja; Ranka, Renāte; Bandere, Dace
Neskatoties uz būtiskiem sasniegumiem tuberkulozes (TB) diagnostikā, ārstēšanā un profilaksē, slimība joprojām ir globāli nozīmīgs sabiedrības veselības izaicinājums un novērota tikai ierobežota incidences samazināšanās. Pēdējos gados Mycobacterium tuberculosis izolātu pilna genoma sekvencēšana (whole-genome sequencing, WGS) ir kļuvusi par vadošo pieeju dažādu aspektu izpētē TB gadījumos, nodrošinot detalizētus ieskatus celmu filoģenētiskajā daudzveidībā, kā arī atziņas par zāļu rezistences mehānismiem, slimības transmisijas dinamiku un recidīvu cēloņiem. Lai gan M. tuberculosis WGS sniedz daudzsološu alternatīvu plaši lietotām molekulāro un fenotipisko analīžu metodēm, papildu uzlabojumi ir nepieciešami sekvencēšanas datu analīzes stratēģijās, lai maksimāli izmantotu WGS potenciālās iespējas, risinot nozīmīgas zinātniskas, epidemioloģiskas un klīniskas TB kontroles problēmas. Šī promocijas darba mērķis bija veikt M. tuberculosis izolātu WGS no pacientiem Latvijā, lai izpētītu TB kontroli ietekmējošas epidemioloģiski un klīniski nozīmīgas neatrisinātās problēmas un piedāvātu uzlabojumus esošajās datu analīzes stratēģijās. Šajā pētījumā galvenokārt tika analizētas divas TB pacientu izlases: pacienti ar TB recidīviem un potenciāli iesaistītie TB transmisijas klasteros, pamatojoties uz epidemioloģiskajiem datiem un konvencionālās genotipēšanas rezultātiem. Pētāmajā populācijā tika iekļauti pieaugušie un bērni ar plaušu vai ārpusplaušu TB. M. tuberculosis izolātiem tika veikta WGS uz ģenētiskajiem variantiem balstītai celmu genotipēšanai, filoģenētiskajām analīzēm, TB recidīvu cēloņu noteikšanai, epidemioloģiski nozīmīgu TB klasteru identifikācijai, transmisijas ķēžu analīzei, vairāku celmu koinfekciju noteikšanai un uz WGS datiem balstītai zāļu jutības pārbaudei. Pētījumam nepieciešamie klīniskie un epidemioloģiskie dati, kā arī iepriekš veikto M. tuberculosis izolātu analīžu rezultāti tika atlasīti no pacientu medicīniskās dokumentācijas. Konvencionālās genotipēšanas (spoligotipēšanas un insercijas sekvences 6110 restrikcijas fragmentu garuma polimorfisma analīzes) un fenotipiskās zāļu jutības pārbaudes dati tika salīdzināti ar WGS rezultātiem. Pacientu diagnozes, krēpu mikroskopiskās izmeklēšanas rezultāti, paraugu iegūšanas datumi, kā arī kontaktpersonu izsekošanas un ģeotelpiskie dati tika integrēti WGS rezultātu interpretācijā atbilstoši analīzes mērķim. WGS datu analīzes rezultātā noteiktās celmu līnijas (lineage) un apakšlīnijas (sub-lineage) bija atbilstošas pētāmo M. tuberculosis izolātu spoligotipēšanas rezultātiem. Iegūtie dati liecināja par ievērojamu M. tuberculosis genotipu daudzveidību Latvijā, ņemot vērā specifiskās pētāmās TB pacientu izlases. Divu Latvijā izplatītāko M. tuberculosis genotipu – Beijing un LAM – izolātiem bija tuvāka ģenētiskā radniecība nekā citu identificēto genotipu izolātiem, turklāt tika novērots atšķirīgs zāļu rezistences sastopamības biežums starp dažādiem M. tuberculosis spoligotipiem. TB recidīvu cēloņu noteikšana, kas paredz endogēnas reaktivācijas diferencēšanu no eksogēnas reinfekcijas, bija precīzāka, kad tika veikta kā daļa no TB klastera transmisijas ķēdes analīzes. Šī pieeja apvieno WGS datu analīzi ar būtisku klīnisko un epidemioloģisko informāciju, jo ar viena nukleotīda variantu (single nucleotide variant, SNV) distances noteikšanu un atšķirīgu SNV analīzi starp izolātiem nebija pietiekami informatīvi. Ģenētiskās distances sliekšņu piemērošana epidemioloģiski nozīmīgu TB klasteru (12 SNV) un nesenas transmisijas gadījumu (5 SNV) noteikšanai izrādījās efektīva zemas līdz vidējas TB incidences apstākļos. Tomēr, identificējot TB klasterus, ir jāņem vērā Latvijā izplatītāko Beijing un LAM genotipu izolātu tuvā ģenētiskā radniecība, lai novērstu kļūdainu klasterizāciju. TB transmisijas ķēžu analīzi ierobežoja neidentificēti aktīvas TB gadījumi, M. tuberculosis mutācijas ātruma mainīgums, zems patogēna ģenētiskais mainīgums un īss laika intervāls starp paraugu iegūšanas datumiem ģenētiski identisku izolātu gadījumos. Piedāvātā integrētā pieeja būtiski papildināja epidemioloģiskās izmeklēšanas un konvencionālās genotipēšanas rezultātus, nodrošinot precīzāku infekcijas avotu noteikšanu un indeksa gadījumu (index case) izvērtēšanu. Taču šī pieeja var nebūt nepieciešama visu epidemioloģiski nozīmīgu gadījumu analīzei. Visbeidzot, nesakritības starp pētāmo izolātu fenotipisko un uz WGS datiem balstīto zāļu jutības pārbaudi tika pamatotas ar fenotipisko testu tehnisko sarežģītību, ģenētisko variantu mainīgo ietekmi uz medikamentu minimālo inhibējošo koncentrāciju, kā arī nepietiekamo informāciju par zāļu rezistenci izraisošiem variantiem. Lai gan uz WGS datiem balstītā zāļu jutības pārbaude nespēj aizstāt fenotipisko metodi pilnībā, abu pieeju kombinācija nodrošina visprecīzāko zāļu rezistences profila novērtējumu. Noslēgumā – pētījums ir sniedzis vērtīgas atziņas par TB transmisijas dinamiku Latvijā, valstī cirkulējošo M. tuberculosis genotipu ģenētisko daudzveidību un zāļu rezistenci izraisošu ģenētisko variantu izplatību šo genotipu starpā. Tika akcentēti izaicinājumi zāļu jutības pārbaudes metodēs, izvērtētas trīs uz WGS datu analīzi balstītās stratēģijas recidīvu cēloņu noteikšanai un piedāvāta integrētā pieeja transmisijas ķēžu analīzei. Pētījuma rezultāti apstiprina WGS ieviešanas potenciālu rutīnas praksē kā daļu no vietējās TB uzraudzības programmas.
Pharmacogenetic Aspects of Anti-Tuberculosis Therapy in Latvian Population. Doctoral Thesis
(Rīga Stradiņš University, 2025) Ulanova (Igumnova), Viktorija; Ranka, Renāte; Bandere, Dace
Pharmacogenetics (PGx) plays a crucial role in personalised medicine by revealing how genetic variations influence drug response, guiding initial doses, and working in conjunction with therapeutic drug monitoring (TDM) to adjust dosing according to drug metabolism for each individual. Together, PGx and TDM work synergistically to optimise treatment, as using the patient’s PGx profile and up-to-date patient data on drug levels in the systemic circulation enables precision, effectiveness and safety of treatment, moving away from a one-size-fits-all approach to a more individualised strategy. Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb), which is transmitted between humans through the respiratory tract, most commonly affecting the lungs. TB is a major global public health challenge and social threat worldwide. With the increasing population mobility and travel, TB strains, including drug-resistant variants, are easily disseminated worldwide. The implementation of personalised medicine strategies may help to ensure the effectiveness of existing treatments, promptly identify those patients most likely to develop adverse drug reactions (ADRs), and reduce the likelihood of acquired drug resistance in Mtb, thus playing an important role in the global fight against TB. This Thesis describes the PGx aspects of TB treatment focusing on the Latvian population. Isoniazid (INH) is a cornerstone of the standard regimen for the treatment of drug-susceptible TB (DS-TB). However, the variability in pharmacokinetic (PK) parameters and drug plasma levels may affect drug response and lead to ADRs including a drug-induced hepatotoxicity (DIH). This Thesis primarily investigates the impact of changes in INH PK parameters due to genetic variability in three genes encoding INH-metabolising enzymes, together with a number of patient-related factors, on the response to anti-TB treatment and the risk of DIH in patients with DS-TB. In particular, the N-acetyltransferase 2 (NAT2) haplotype, referred to as acetylator status, and the genotype of glutathione S-transferase M1 class (GSTM1) were assessed in TB patients. Additionally, a new next-generation sequencing-based method for full-length cytochrome P450 family 2 subfamily E member 1 (CYP2E1) gene analysis was designed and evaluated to determine whether CYP2E1 gene variants are of clinical significance. Aminoglycosides (AGs) are potent, broad-spectrum antibiotics, which remain important drugs in the treatment of multidrug-resistant TB. AG-induced hearing loss (AIHL) is a well-recognised ADR with rapid, profound, and irreversible hearing loss that can occur in predisposed individuals. The MT-RNR1 gene, encoding the mitochondrial ribosomal 12S subunit, is particularly susceptible to gene variants associated with AIHL. In this Thesis, the prevalence of AIHL-related MT-RNR1 gene variants was investigated in the Baltic-speaking ethnic Latvian population in comparison to the general population worldwide in order to improve the accuracy and safety of treatment with AGs. This Thesis is presented as a comprehensive compilation of peer-reviewed publications, summarising advancements in personalised TB medicine. Specifically, it focuses on identifying and characterising the factors that contribute to variations in drug response and safety through comprehensive analysis of the PGx and PK data in TB patients. This approach could provide us with an opportunity to advance therapeutic decision-making. The inclusion of profiling of INH and its two main metabolites in clinical studies, together with PGx screening, could be beneficial in determining optimal dosing strategies, tailoring treatment regimens, and fostering a patient-centred healthcare approach for TB patients, challenging the current paradigm of modern public health.
Pharmacogenetic Aspects of Anti-Tuberculosis Therapy in Latvian Population. Summary of the Doctoral Thesis
(Rīga Stradiņš University, 2025) Ulanova (Igumnova), Viktorija; Ranka, Renāte; Bandere, Dace
Pharmacogenetics (PGx) plays a crucial role in personalised medicine by revealing how genetic variations influence drug response, guiding initial doses, and working in conjunction with therapeutic drug monitoring (TDM) to adjust dosing according to drug metabolism for each individual. Together, PGx and TDM work synergistically to optimise treatment, as using the patient’s PGx profile and up-to-date patient data on drug levels in the systemic circulation enables precision, effectiveness and safety of treatment, moving away from a one-size-fits-all approach to a more individualised strategy. Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb), which is transmitted between humans through the respiratory tract, most commonly affecting the lungs. TB is a major global public health challenge and social threat worldwide. With the increasing population mobility and travel, TB strains, including drug-resistant variants, are easily disseminated worldwide. The implementation of personalised medicine strategies may help to ensure the effectiveness of existing treatments, promptly identify those patients most likely to develop adverse drug reactions (ADRs), and reduce the likelihood of acquired drug resistance in Mtb, thus playing an important role in the global fight against TB. This Thesis describes the PGx aspects of TB treatment focusing on the Latvian population. Isoniazid (INH) is a cornerstone of the standard regimen for the treatment of drug-susceptible TB (DS-TB). However, the variability in pharmacokinetic (PK) parameters and drug plasma levels may affect drug response and lead to ADRs including a drug-induced hepatotoxicity (DIH). This Thesis primarily investigates the impact of changes in INH PK parameters due to genetic variability in three genes encoding INH-metabolising enzymes, together with a number of patient-related factors, on the response to anti-TB treatment and the risk of DIH in patients with DS-TB. In particular, the N-acetyltransferase 2 (NAT2) haplotype, referred to as acetylator status, and the genotype of glutathione S-transferase M1 class (GSTM1) were assessed in TB patients. Additionally, a new next-generation sequencing-based method for full-length cytochrome P450 family 2 subfamily E member 1 (CYP2E1) gene analysis was designed and evaluated to determine whether CYP2E1 gene variants are of clinical significance. Aminoglycosides (AGs) are potent, broad-spectrum antibiotics, which remain important drugs in the treatment of multidrug-resistant TB. AG-induced hearing loss (AIHL) is a well-recognised ADR with rapid, profound, and irreversible hearing loss that can occur in predisposed individuals. The MT-RNR1 gene, encoding the mitochondrial ribosomal 12S subunit, is particularly susceptible to gene variants associated with AIHL. In this Thesis, the prevalence of AIHL-related MT-RNR1 gene variants was investigated in the Baltic-speaking ethnic Latvian population in comparison to the general population worldwide in order to improve the accuracy and safety of treatment with AGs. This Thesis is presented as a comprehensive compilation of peer-reviewed publications, summarising advancements in personalised TB medicine. Specifically, it focuses on identifying and characterising the factors that contribute to variations in drug response and safety through comprehensive analysis of the PGx and PK data in TB patients. This approach could provide us with an opportunity to advance therapeutic decision-making. The inclusion of profiling of INH and its two main metabolites in clinical studies, together with PGx screening, could be beneficial in determining optimal dosing strategies, tailoring treatment regimens, and fostering a patient-centred healthcare approach for TB patients, challenging the current paradigm of modern public health.
Polifenolus saturošu augu ekstraktu antioksidatīvā un antibakteriālā iedarbība pret govs mastīta izraisītājiem. Promocijas darba kopsavilkums
(Rīgas Stradiņa universitāte, 2025) Teterovska (Šukele), Renāte; Bandere, Dace; Koka, Rudīte
Govs mastīts ir bakteriāls tesmeņa iekaisums, ko parasti ārstē ar antibiotikām. Slimības ārstēšana un antibiotiku atliekvielas pienā rada ievērojamus zaudējumus saimniecībām. Antibiotiku nepareiza un pārmērīga lietošana ir radījusi antibiotiku rezistenci baktērijās un rada globālus draudus veselības aprūpē. Līdz ar to tiek meklēti alternatīvi risinājumi mastīta profilaksei un ārstēšanai. Ārstniecības augi ir izmantoti gadsimtiem ilgi tautas medicīnā arī dzīvnieku aprūpē ne tikai to antibakteriālo īpašību dēļ, bet arī antioksidantu īpašību, kas veicina atveseļošanos. Diemžēl trūkst pētījumu par pielietojumu veterinārā medicīnā. Šī pētījuma mērķis bija noteikt augu ekstraktu polifenolu sastāvu un to farmakoloģiskos efektus mastīta ārstēšanā. Pētījumā tika izmantoti žāvētu augu ekstrakti (ozola miza, biškrēsliņa zieds un lapa, virša laksts), kas pagatavoti, macerējot ar 30 %, 50 %, 70 % etalonu vai acetonu. Pēc ekstrakcijas šķīdumi tika ietvaicēti un liofilizēti. Tika noteikts kopējais polifenolu, flavonoīdu un miecvielu daudzums ekstraktos. Izmantojot Furjē transformācijas infrasarkanā starojuma spektrometriju (FTIR) un augstas precizitātes šķīdumu hromatogrāfiju (HPLC), raksturots augu polifenolu sastāvs. Izmantojot mikroatšķaidīšanas metodes, noteikta augu ekstraktu antibakteriālā darbība pret govs mastīta izraisītājiem Escherichia coli, Streptococcus agalactiae, Streptococcus uberis, Serratia liquefaciens, Staphylococcus aureus, un divām references kultūrām: S. aureus un E.coli. Visi analizētie ekstrakti saturēja ievērojamu daudzumu polifenolu tipa savienojumu, arī iepriekš mazāk aprakstītās miecvielas, kurām piemīt būtiskas farmakoloģiskas īpašības. Ekstraktu sastāvs un aktivitāte ir saistāma ar izvēlēto šķīdinātāju veidu un koncentrāciju. Visiem ekstraktiem bija nozīmīgs efekts pret S. aureus, bet pret pārējiem mastīta ierosinātājiem rezultāts bija atkarīgs no auga un ekstrakta veida. Augu ekstraktiem piemīt arī antioksidantu īpašības, kas saistāms ar polifenoliem to sastāvā. Ozola mizas, viršu lakstu, biškrēsliņu lapu un ziedu ekstraktiem ir antibakteriālas un antioksidanta īpašības pret mastīta izraistītājiem in vitro, un to var izmantot veterināra produkta izveidē.
Prettuberkulozes terapijas farmakoģenētiskie aspekti Latvijas populācijā. Promocijas darba kopsavilkums
(Rīgas Stradiņa universitāte, 2025) Ulanova (Igumnova), Viktorija; Ranka, Renāte; Bandere, Dace
Farmakoģenētikai (angl. PGx) ir izšķiroša nozīme personalizētajā medicīnā, jo tā palīdz atklāt, kā ģenētiskās variācijas ietekmē pacienta reakciju uz zālēm. Tas ļauj precīzāk noteikt sākotnējās zāļu devas, un apvienojot ar zāļu terapeitisko uzraudzību (angl. TDM) pielāgot zāļu devu katram pacientam, balstoties uz viņu individuālo zāļu metabolismu. PGx un TDM darbojas sinerģiski, lai optimizētu ārstēšanu, nodrošinot ārstēšanas precizitāti, efektivitāti un drošumu. Pacienta PGx profila kombinēšana ar aktuāliem datiem par zāļu līmeni sistēmiskajā cirkulācijā ļauj pāriet no pieejas "viens izmērs der visiem" uz individualizētām terapijas stratēģijām. Tuberkuloze (TB) ir infekcijas slimība, ko izraisa mikobaktērija Mycobacterium tuberculosis (Mtb). TB izplatās gaisa pilienu ceļā no cilvēka uz cilvēku un visbiežāk skar plaušas. Šī infekcija ir nozīmīga globāla sabiedrības veselības problēma un sociāls drauds. Pieaugot iedzīvotāju mobilitātei un ceļotāju migrācijai, Mtb celmi, tostarp pret zālēm rezistenti varianti, viegli izplatās visā pasaulē. Personalizētās medicīnas stratēģiju ieviešana var būtiski uzlabot esošās ārstēšanas efektivitāti, savlaicīgi identificējot pacientus ar augstu zāļu nevēlamu blakusparādību (angl. ADRs) risku, kā arī samazināt zāļu rezistences rašanās iespējas pret Mtb. Šāda pieeja spēlē nozīmīgu lomu globālajā cīņā pret TB. Šajā disertācijā ir aprakstīti TB ārstēšanas PGx aspekti ar īpašu uzsvaru uz Latvijas iedzīvotājiem. Izoniazīds (angl. INH) ir standarta ārstēšanas shēmas stūrakmens pret zālēm jūtīgās TB (angl. DS-TB) gadījumos. Tomēr farmakokinētisko (angl. PK) parametru un zāļu līmeņa mainīgums asins plazmā var ietekmēt TB ārstēšanas efektivitāti vai izraisīt ADRs, piemēram, zāļu izraisītu aknu bojājumu (angl. DIH). Šajā promocijas darbā galvenā uzmanība tika pievērsta INH PK parametru izmaiņām, ko izraisa INH metabolizējošo enzīmu kodējošo gēnu ģenētiskā variabilitāte un dažādi ar pacientu saistīti faktori, analizējot to ietekmi uz terapijas atbildes reakciju un DIH attīstības risku pacientiem ar DS-TB. Īpašs uzsvars tika likts uz N-acetiltransferāzes 2 (NAT2) acetilatora statusu, glutationa S-transferāzes M1 klases (GSTM1) genotipu. Turklāt tika izstrādāta un izvērtēta jauna metode, kas balstīta uz nākamās paaudzes sekvencēšanu, lai veiktu pilna garuma citohroma P450 2. saimes E apakšsaimes 1. locekļa (CYP2E1) gēna analīzi. Šī pieeja tika izmantota, lai novērtētu, vai vairāku reģionu CYP2E1 gēna variantiem ir klīniskā nozīme. Aminoglikozīdi (AG) ir spēcīgas plaša spektra antibiotikas, kurām joprojām ir būtiska loma multirezistentās TB ārstēšanā. Tomēr AG izraisīts dzirdes zudums (angl. AIHL) ir labi pazīstama un atzīta ADR. Tas izpaužas kā ātrs, dziļš un neatgriezenisks dzirdes zudums, kas īpaši bieži novērojamas pacientiem ar ģenētisku predispozīciju. MT-RNR1 gēns, kas kodē mitohondriālo ribosomālo 12S apakšvienību, ir īpaši uzņēmīgs pret gēna variantiem, kas saistīti ar AIHL. Šajā promocijas darbā tika pētīta ar AIHL saistītu MT-RNR1 gēna variantu prevalence Latvijas populācijā un salīdzināta ar globālajām populācijām. Pētījuma mērķis bija sekmēt AG lietošanas drošumu un veicināt ārstēšanas precizitāti. Šī disertācija ir veidota kā visaptveroša recenzētu publikāciju kopa, kurā apkopoti pētījumi personalizētās medicīnas jomā. Tajā īpaša uzmanība pievērsta faktoriem, kas ietekmē zāļu atbildes reakcijas un drošuma atšķirības, kā arī šo faktoru identificēšanai un raksturošanai, izmantojot visaptverošu PGx un PK datu analīzi pacientiem ar TB. Šāda pieeja var sniegt nozīmīgu ieguldījumu terapeitisko lēmumu pieņemšanā. INH un tā divu galveno metabolītu koncentrācijas uzraudzība un PGx skrīninga iekļaušana klīniskajos pētījumos varētu būt lietderīga optimālu dozēšanas stratēģiju noteikšanai, ārstēšanas režīmu pielāgošanai un pacientu orientētas veselības aprūpes pieejas veicināšanai pacientiem ar TB. Šis darbs izaicina pašreizējo modernās sabiedrības veselības aprūpes paradigmu, piedāvājot personalizētākas un efektīvākas ārstēšanas iespējas.

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