4,215 research outputs found
Production, Functional Characterization and Inhibition of Carbonic Anhydrases of Parasites
Hiilihappoanhydraasit (carbonic anhydrase, CA) ovat metalloentsyymejä, joita esiintyy kaikkialla elollisessa luonnossa. Niiden tehtävä on katalysoida elintärkeää käänteistä reaktiota: hiilidioksidin hydraatiota hiilihapoksi (CO2 + H2O ⇋ H2CO3 ⇋ HCO3- + H+). Reaktio on osana monissa fysiologisissa ja metabolisissa prosesseissa, kuten happo-emästasapainon säätelyssä, glukoneogeneesissa ja yhteyttämisessä. Hiilihappoanhydraasit jaetaan yhteensä kahdeksaan perheeseen, joista ihmisillä esiintyy vain ensimmäisenä löydettyä α-entsyymiperhettä. Monilla taudinaiheuttajilla, kuten bakteereilla ja loisilla, on myös muiden hiilihappoanhydraasiperheiden proteiineja.
Schistosoma mansoni on suolistotulehdusta aiheuttava halkiomato, jota esiintyy endeemisenä monilla trooppisilla ja subtrooppisilla seuduilla. Entamoeba histolytica ja Acanthamoeba castellanii ovat ihmisille infektioita aiheuttavia ameboja. E. histolytica aiheuttaa suolistotulehdusta ja A. castellanii pääasiassa sarveiskalvon tulehdusta, sekä immuunipuutteisille henkilöille myös syviä infektioita. Yhteistä näille loisille on, että niiden diagnostiikassa tai hoidossa on puutteita, ja ne ovat globaalisti erittäin yleisiä. Niiden aiheuttamat sairaudet voivat olla tappavia, ja aiheuttavat lievimmilläänkin merkittävää elämänlaadullista haittaa. Väitöskirjatutkimukseni tavoitteena on löytää nopeampi menetelmä tunnistaa A. castellanii biologisesta näytteestä sekä löytää uusia potentiaalisia lääkeainemolekyylejä näiden kolmen loisen aiheuttamien sairauksien tehokkaammaksi hoitamiseksi.
Väitöstutkimuksessani tuotin E. histolytican ja S. mansonin β-hiilihappoanhydraasit Escherichia coli -bakteereissa. Tutkimme hiilihappoanhydraasien inhibiittorien vaikutusta tuotettuihin entsyymeihin, ja löysimme useita lupaavia inhibiittoreita. Lisäksi kehitimme uuden nopean diagnostisen menetelmän A. castellaniin havaitsemiseksi näytteestä, sillä nykyinen ameban viljelyyn perustuva menetelmä on kliiniseen diagnostiikkaan liian hidas. Nykyiset A. castellaniin aiheuttamien infektioiden hoitoon käytetyt lääkkeet ovat vain kohtalaisen tehokkaita ja niihin liittyy useita haittavaikutuksia, joten kehitimme uuden menetelmän uusien lääkeaineiden etsimistä varten ja testasimme useita, jo kliinisessä käytössä olevia hiilihappoanhydraasin estäjiä menetelmällämme.
Havaitsimme, että dorsolamidi ja asetatsoliamidi ovat lupaavia uusia vaihtoehtoja akantamebakeratiitin hoitamiseksi. Niiden etuna on pitkään jatkunut käyttö ihmispotilaiden muiden sairauksien hoidossa, joten niiden haitta- ja sivuvaikutukset ovat tunnettuja. Valitettavasti asetatsoliamidi on vain kohtalaisen tehokas inhiboimaan E. histolytican ja S. mansonin β-hiilihappoanhydraaseja. Dorsolamidi on tehokas inbiittori S. mansonin β-hiilihappoanhydraasia vastaan, toisin kuin E. histolytican β-hiilihappoanhydraasia se inhiboi huonosti. Onneksi moni muu inhibiittori on tehokas estämään niiden molempien toimintaa.
Tämä väitöskirja lisää tietoa ja mahdollisuuksia hyödyntää hiilihappoanhydraaseja loisinfektioiden diagnostiikassa ja hoidossa.Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes that can be found in almost all living organisms. They catalyze a vital chemical reaction: the reversible hydration of carbon dioxide (CO2 + H2O ⇋ H2CO3 ⇋ HCO3− + H+). It is part of multiple physiological and metabolic processes, such as p regulation, gluconeogenesis and photosynthesis. CAs are divided into eight families, from which the human genome only involves α-CAs. Many pathogens, such as bacteria and parasites, also have CA enzymes from other families.
Schistosoma mansoni is a parasitic blood fluke that causes intestinal infection in many tropical and subtropical areas. Entamoeba histolytica and Acanthamoeba castellanii are amoebae that cause different infections in humans. E. histolytica causes intestinal infection, and A. castellanii mainly infects the cornea but also causes invasive infections in immunocompromised people. The infections of these parasites are common globally, and unfortunately, the diagnosis and treatment are often delayed. The infections can be lethal, and at their mildest, they cause a significant reduction in the quality of life. My study aims to find a faster and more effective way to detect A. castellanii from a biological sample and discover new potential drug candidates to treat these parasitic infections.
In my thesis, I produced the β-CAs of E. histolytica and S. mansoni using Escherichia coli as a protein production organism. We studied the inhibitory effects of many known CA inhibitors and identified several promising candidates or potential leads for further development. In addition, we developed a novel rapid diagnostic method to detect A. castellanii from a biological sample. The novel method could replace the current gold standard, sample culture, which is slow in clinical diagnostics. We established a new method to investigate potential drug candidates for treating A. castellanii, as the current treatment options are only moderately effective and have many adverse side effects. By this method, we tested several clinically used CA inhibitors with interesting outcomes.
Dorzolamide and acetazolamide were found to be new promising options for
treating Acanthamoeba keratitis. The advantage of these drugs is also the long use history with human patients in treating other conditions, which has made the side effects and risks very familiar to medical staff. Unfortunately, acetazolamide was only moderately effective against the β-CAs of S. mansoni and E. histolytica, as was dorzolamide against the β-CA of E. histolytica. In contrast, dorzolamide was an effective inhibitor against the β-CA of S. mansoni. We also found many other effective inhibitors against the β-CAs of E. histolytica and S. mansoni.
This thesis increases the knowledge and options to use the CAs of parasites to diagnose and treat infections caused by parasites
Exploring missing heritability in neurodevelopmental disorders:Learning from regulatory elements
In this thesis, I aimed to solve part of the missing heritability in neurodevelopmental disorders, using computational approaches. Next to the investigations of a novel epilepsy syndrome and investigations aiming to elucidate the regulation of the gene involved, I investigated and prioritized genomic sequences that have implications in gene regulation during the developmental stages of human brain, with the goal to create an atlas of high confidence non-coding regulatory elements that future studies can assess for genetic variants in genetically unexplained individuals suffering from neurodevelopmental disorders that are of suspected genetic origin
Evolutionary ecology of obligate fungal and microsporidian invertebrate pathogens
The interactions between hosts and their parasites and pathogens are omnipresent in the natural world. These symbioses are not only key players in ecosystem functioning, but also drive genetic diversity through co-evolutionary adaptations. Within the speciose invertebrates, a plethora of interactions with obligate fungal and microsporidian pathogens exist, however the known interactions is likely only a fraction of the true diversity. Obligate invertebrate fungal and microsporidian pathogen require a host to continue their life cycle, some of which have specialised in certain host species and require host death to transmit to new hosts. Due to their requirement to kill a host to spread to a new one, obligate fungal and microsporidian pathogens regulate invertebrate host populations. Pathogen specialisation to a single or very few hosts has led to some fungi evolving the ability to manipulate their host’s behaviour to maximise transmission. The entomopathogenic fungus, Entomophthora muscae, infects houseflies (Musca domestica) over a week-long proliferation cycle, resulting in flies climbing to elevated positions, gluing their mouthparts to the substrate surface, and raising their wings to allow for a clear exit from fungal conidia through the host abdomen. These sequential behaviours are all timed to occur within a few hours of sunset. The E. muscae mechanisms used in controlling the mind of the fly remain relatively unknown, and whether other fitness costs ensue from an infection are understudied.European Commissio
Effects of municipal smoke-free ordinances on secondhand smoke exposure in the Republic of Korea
ObjectiveTo reduce premature deaths due to secondhand smoke (SHS) exposure among non-smokers, the Republic of Korea (ROK) adopted changes to the National Health Promotion Act, which allowed local governments to enact municipal ordinances to strengthen their authority to designate smoke-free areas and levy penalty fines. In this study, we examined national trends in SHS exposure after the introduction of these municipal ordinances at the city level in 2010.MethodsWe used interrupted time series analysis to assess whether the trends of SHS exposure in the workplace and at home, and the primary cigarette smoking rate changed following the policy adjustment in the national legislation in ROK. Population-standardized data for selected variables were retrieved from a nationally representative survey dataset and used to study the policy action’s effectiveness.ResultsFollowing the change in the legislation, SHS exposure in the workplace reversed course from an increasing (18% per year) trend prior to the introduction of these smoke-free ordinances to a decreasing (−10% per year) trend after adoption and enforcement of these laws (β2 = 0.18, p-value = 0.07; β3 = −0.10, p-value = 0.02). SHS exposure at home (β2 = 0.10, p-value = 0.09; β3 = −0.03, p-value = 0.14) and the primary cigarette smoking rate (β2 = 0.03, p-value = 0.10; β3 = 0.008, p-value = 0.15) showed no significant changes in the sampled period. Although analyses stratified by sex showed that the allowance of municipal ordinances resulted in reduced SHS exposure in the workplace for both males and females, they did not affect the primary cigarette smoking rate as much, especially among females.ConclusionStrengthening the role of local governments by giving them the authority to enact and enforce penalties on SHS exposure violation helped ROK to reduce SHS exposure in the workplace. However, smoking behaviors and related activities seemed to shift to less restrictive areas such as on the streets and in apartment hallways, negating some of the effects due to these ordinances. Future studies should investigate how smoke-free policies beyond public places can further reduce the SHS exposure in ROK
Evaluation of mixed microalgae species biorefinery of Desmodesmus sp. And Scenedesmus sp. For bioproducts synthesis
Microalgae is known to produce numerous bioactive compounds for instance proteins, fatty acid, polysaccharides, enzymes, sterols, and antioxidants. Due to their valuable biochemical composition, microalgae are regarded as a very intriguing source to produce novel food products and can be utilised to improve the nutritional content of traditional foods. Additionally, microalgae are used as animal feed and additives in the cosmetics, pharmaceutical as well as nutraceutical industries. As compared to other terrestrial plants and other microorganisms, microalgae possess few advantages: (1) rapid growth rate; (2) able to grow in non-arable land and harsh cultivation conditions; (3) low nutritional requirements; (4) high productivity; and (5) reduce emission of carbon dioxide. Despite the large number of microalgae species found in nature, only a few species are identified and commercialized such as Chlorella sp., Spirulina sp. Haematococcus pluvialis, Nannochloropsis sp. and Chlamydomonas reinhardtii, which is one of the major obstacles preventing the full utilisation of microalgae-based technology.
This thesis provides information on the overall composition of mixed microalgae species, Desmodesmus sp. and Scenedesmus sp., for instance protein, carbohydrate, lipid, antioxidants, and pigment. This thesis firstly introduces the application of triphasic partitioning (TPP) in the extraction and partitioning of the biomolecules from the microalgae. The latest advancement of technology has evolved from a liquid biphasic flotation (LBF) to TPP. T-butanol and ammonium sulphate are used in TPP to precipitate desired biomolecules from the aqueous solutions with the formation of three layer. TPP is a simple, time- and cost- efficient, as well as scalable process that does not require toxic organic solvents. Lipase is abundantly produced by microbes, bacteria, fungi, yeast, mammals, and plants. Lipase is widely used in the oleochemical, detergent, dairy, leather, cosmetics, paper, cosmetics, and nutraceutical industries. Therefore, this thesis also discusses the possibility of identifying and extracting enzyme lipase from the microalgae using LBF. Several parameters (volume and concentration of solvents, weight of biomass, flotation kinetics and solvent types, etc.) have been investigated to optimize the lipase extraction from LBF.
Chlorophyll is the main pigment present in the microalgae. Thus, this work proposes the digital imaging approach to determine the chlorophyll concentration in the microalgae rapidly because the chlorophyll content has a significant impact on microalgae physiological health status as well as identifies the chlorophyll concentration in the production of by-products. Lastly, microalgae oil can be used as the feedstock for biodiesel as well as nutraceutical, pharmaceutical, and health-care products. The challenge in the lipid extraction is the co-extraction of chlorophyll into the oil, which can have serious consequences for downstream processing. Therefore, the removal of the chlorophyll from the microalgae using activated clay or sodium chlorite in the pre-treatment procedure are examined. The research achievements in these works and future opportunities are highlighted in the last chapter of the thesis
Analytical validation of innovative magneto-inertial outcomes: a controlled environment study.
peer reviewe
AI: Limits and Prospects of Artificial Intelligence
The emergence of artificial intelligence has triggered enthusiasm and promise of boundless opportunities as much as uncertainty about its limits. The contributions to this volume explore the limits of AI, describe the necessary conditions for its functionality, reveal its attendant technical and social problems, and present some existing and potential solutions. At the same time, the contributors highlight the societal and attending economic hopes and fears, utopias and dystopias that are associated with the current and future development of artificial intelligence
Deep learning for computer vision constrained by limited supervision
This thesis presents the research work conducted on developing algo- rithms capable of training neural networks for image classification and re- gression in low supervision settings. The research was conducted on publicly available benchmark image datasets as well as real world data with appli- cations to herbage quality estimation in an agri-tech scope at the VistaMilk SFI centre. Topics include label noise and web-crawled datasets where some images have an incorrect classification label, semi-supervised learning where only a small part of the available images have been annotated by humans and unsupervised learning where the images are not annotated. The principal contributions are summarized as follows. Label noise: a study highlighting the dual in- and out-of-distribution nature of web-noise; a noise detection metric than can independently retrieve each noise type; an observation of the linear separability of in- and out-of-distribution images in unsupervised contrastive feature spaces; two noise-robust algorithms DSOS and SNCF that iteratively improve the state-of-the-art accuracy on the mini-Webvision dataset. Semi-supervised learning: we use unsupervised features to propagate labels from a few labeled examples to the entire dataset; ReLaB an algorithm that allows to decrease the classification error up to 8% with one labeled representative image on CIFAR-10. Biomass composition estimation from images: two semi-supervised approaches that utilize unlabeled images either through an approximate annotator or by adapting semi-supervised algorithms from the image classification litterature. To scale the biomass to drone images, we use super-resolution paired with semi-supervised learning. Early results on grass biomass estimation show the feasibility of automating the process with accuracies on par or better than human experts. The conclusion of the thesis will summarize the research contributions and discuss thoughts on future research that I believe should be tackled in the field of low supervision computer vision
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