DESIGN OF A HIGH-THROUGHPUT METHODFOR THE ASSESSMENT OF ENZYME ACTIVITY UPON ADSORPTION ONCLUSTER-ASSEMBLED NANOSTRUCTURED TITANIUM OXIDE FILMS

Control of nanometre-scale topography of solid surfaces has opened the possibility to tailor the interactions between materials and biomolecules maintaining the biological functions of these molecules, a crucial aspect for diverse biomaterial applications. However, the primary mechanisms that dictate protein adsorption to topographical nanostructures are often poorly understood. We have addressed this question by scrutinizing the catalytic activity of immobilized serine-protease trypsin as product of its adsorption properties on cluster-assembled nanostructured titania films. Both, adsorption and activity of surface-bound enzymes were evaluated in parallel using innovative microarray-based methodology developed in this PhD work. Trypsin adsorption analysis demonstrated an increment with roughness of Langmuir parameters \u2013 saturation uptake and equilibrium dissociation constant, that exceeded the contribution predicted by increase in sample specific area. This finding was interpreted by the clustering of protein molecules inside titania surface nanopores, a model proposed in our previous study of three non-enzymatic proteins. The growth of adsorbed trypsin activity with roughness was attributed to the increase in specific area of titania films, whereas the drop in specific activity resulted from steric hindrance of trypsin clustered inside titania nanopores. This study has shed light on the topographical determinants of trypsin adsorption on nanostructured titania surfaces and its impact on trypsin activity. A novel method was developed elucidating the obstacles and specifics of protease immobilization by physisorption and suggesting possible routes to solve them. This methodology is directly applicable in biomaterial screening with respect to the functionality of immobilized enzymes and can be extended beyond the trypsin-nanostructured titania model

Idiopathic infertility as a feature of genome instability

Funding Information: The authors are very grateful to habil. med. Jekaterina Erenpreisa for her critical review of the paper. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Genome instability may play a role in severe cases of male infertility, with disrupted spermatogenesis being just one manifestation of decreased general health and increased morbidity. Here, we review the data on the association of male infertility with genetic, epigenetic, and environmental alterations, the causes and consequences, and the methods for assessment of genome instability. Male infertility research has provided evidence that spermatogenic defects are often not limited to testicular dysfunction. An increased incidence of urogenital disorders and several types of cancer, as well as overall reduced health (manifested by decreased life expectancy and increased morbidity) have been reported in infertile men. The pathophysiological link between decreased life expectancy and male infertility supports the notion of male infertility being a systemic rather than an isolated condition. It is driven by the accumulation of DNA strand breaks and premature cellular senescence. We have presented extensive data supporting the notion that genome instability can lead to severe male infertility termed “idiopathic oligo-astheno-teratozoospermia.” We have detailed that genome instability in men with oligo-astheno-teratozoospermia (OAT) might depend on several genetic and epigenetic factors such as chromosomal heterogeneity, aneuploidy, micronucleation, dynamic mutations, RT, PIWI/piRNA regulatory pathway, pathogenic allelic variants in repair system genes, DNA methylation, environmental aspects, and lifestyle factors.Peer reviewe

Alanyl-tRNA synthetase 1 gene variants in hereditary neuropathy genotype and phenotype overview

Funding Information: This research is funded by Latvian Science Council, Project Discovering biomarkers of disease progression and variability in Charcot-Marie-Tooth neuropathy, No lzp-2021/1-0327. Funding Information: The Article Processing Charge was funded by Fundamental and Applied Research Project, lzp-2021/1-0327. Publisher Copyright: Copyright © 2022 The Author(s).Background and Objectives Our objective was to report 2 novel variants and to reclassify previously reported alanyl-tRNA synthetase 1 (AARS1) variants associated with hereditary neuropathy and to summarize the clinical features of a previously published cohort of patients. Methods We performed detailed neurologic and electrophysiologic assessments and segregation analysis of 2 unrelated families with Charcot-Marie-Tooth (CMT) disease with novel variants in the AARS1 gene. Via literature search, we found studies that included neuropathy cases with AARS1 variants; we then reviewed and reclassified these variants. Results We identified 2 CMT families harboring previously unreported likely pathogenic AARS1 variants: c.1823C>A p.(Thr608Lys) and c.1815C>G p.(His605Gln). In addition, we reinterpreted a total of 35 different AARS1 variants reported in cases with neuropathy from the literature: 9 variants fulfilled the current criteria for being (likely) pathogenic. We compiled and summarized standardized clinical and genotypic information for 90 affected individuals from 32 families with (likely) pathogenic AARS1 variants. Most experienced motor weakness and sensory loss in the lower limbs. Discussion In total, 11 AARS1 variants can currently be classified as pathogenic or likely pathogenic and are associated with sensorimotor axonal or intermediate, slowly progressive polyneuropathy with common asymmetry and variable age of symptom onset with no apparent involvement of other organ systems.publishersversionPeer reviewe

Case report : Multiple UGT1A1 gene variants in a patient with Crigler-Najjar syndrome

Publisher Copyright: © 2018 The Author(s).Background: Inherited unconjugated hyperbilirubinemia is caused by variants in the gene UGT1A1 leading to Gilbert's syndrome and Crigler-Najjar syndrome types I and II. These syndromes are differentiated on the basis of UGT1A1 residual enzymatic activity and its affected bilirubin levels and responsiveness to phenobarbital treatment. Case presentation: In this report, we present a boy with Crigler-Najjar syndrome type II with high unconjugated bilirubin levels that decreased after phenobarbital treatment but increased in adolescence. Four different UGT1A1 gene variants have been identified for this patient, of which one is novel (g.11895-11898del) most likely confirming diagnose molecularly. Conclusions: The presented case highlights the challenges encountered with the interpretation of molecular data upon identification of multiple variants in one gene that are causing different degree reducing effect on enzyme activity leading to several clinical conditions.Peer reviewe

Clinical and neurophysiological spectrum of polyneuropathies in children

Peripheral neuropathy is a disorder of the peripheral nerves and results from a disturbance of structure and/or function of the peripheral sensory, motor and/or autonomic neurons. The possible aetiology of peripheral neuropathies is diverse, but inflammatory and hereditary diseases of the peripheral nerves predominate in childhood. The aim of this study was to determine the clinical and electrophysiological profile of large nerve fibre neuropathy detected by nerve conduction studies (NCS) in children over a 10-year period at the Children’s Clinical University Hospital in Latvia. Based on NCS findings, 165 children between 2008 and 2018 were diagnosed with polyneuropathy. In our study, the majority of children had peripheral neuropathy due to acquired causes, mostly due to diabetes mellitus; roughly one in five of the patients had hereditary neuropathy. Almost half of the patients had motor deficits, which were more prevalent in toxic and inflammatory neuropathies. A little less than a third of patients complained of pain as well as presenting with autonomic dysfunction symptoms. The NCS demonstrated a demyelinating neuropathy in 52 cases (31%), an axonal neuropathy in 34 cases (21%), and mixed polyneuropathy in 79 cases (48%). Our study investigated the clinical and electrophysiological characteristics of polyneuropathies diagnosed with NCS in children. Most of the polyneuropathies in our study were hereditary and diabetic neuropathies with combined (myelin and axon) damage to nerve fibres. Almost all clinical symptoms of polyneuropathy were present in all aetiological groups.Peer reviewe

Association of variants in the CP, ATOX1 and COMMD1 genes with Wilson disease symptoms in Latvia

Funding Information: This study was partially financed by a grant of Riga Stradins University, Department of Doctoral studies and grant of Roche Academy. Funding Information: Funding . This study was partially financed by a grant of Riga Stradiņš University, Department of Doctoral studies and grant of Roche Academy. Publisher Copyright: © 2019 Zarina A, Tolmane I, Krumina Z, Tutane AI, Gailite L, published by Sciendo.Wilson's disease (WD) is a copper metabolism disorder, caused by allelic variants in the ATP7B gene. Wilson's disease can be diagnosed by clinical symptoms, increased copper and decreased cerulopasmin levels, which could all also be by other genetic variants beyond the ATP7B gene, e.g., disturbed ceruloplasmin biosynthesis can be caused by pathogenic allelic variants of the CP gene. Copper metabolism in the organism is affected by several molecules, but pathogenic variants and related phenotypes are described with COMMD1 and ATOX1 genes. The aim of the study was to test other genes, CP, ATOX1 and COMMD1, for possible influence to the manifestation of WD. Patients were enrolled on the basis of Leipzig's diagnostic criteria, 64 unrelated patients with confirmed WD. Direct sequencing of promoter region of the CP gene and ATOX1 and COMMD1 gene exons was conducted. Statistically significant differences were found between the two variants in the CP gene and the ATP7B genotype (rs66508328 variant AA genotype and the rs11708215 variant GG genotype) were more common in WD patients with an unconfirmed ATP7B genotype. One allelic (intronic) variant was found in the ATOX1 gene without causing the functional changes of the gene. Three allelic variants were identified in the COMMD1 gene. No statistically significant differences were found between allele and genotype frequencies and the first clinical manifestations of WD. Different variants of the CP gene contributed to a WD-like phenotype in clinically confirmed WD patients with neurological symptoms and without identified pathogenic variants in the ATP7B gene. Allelic variants in the ATOX1 and COMMD1 genes do not modify the clinical manifestation of WD in Latvian patients.publishersversionPeer reviewe

A systematic review and standardized clinical validity assessment of genes involved in female reproductive failure

Genetic testing is becoming increasingly required at almost every stage of failed female reproduction/infertility. Nonetheless, clinical evidence for the majority of identified gene-disease relationships is ill-defined, thus leading to difficult gene variant interpretation and poor translation of existing knowledge into clinics. We aimed to identify the genes that have ever been implicated in monogenic female reproductive failure in humans and to classify the identified gene-disease relationship pairs using a standardized clinical validity assessment. A PubMed search following PRISMA guidelines was conducted on 20 September 2021 aiming to identify studies pertaining to genetic causes of phenotypes of female reproductive failure. The clinical validity of identified gene-disease pairs was assessed using standardized criteria, counting whether sufficient genetic and experimental evidence has been accumulated to consider a single gene 'characterized' for a single Mendelian disease. In total, 1256 articles were selected for the data extraction; 183 unique gene-disease pairs were classified spanning the following phenotypes: hypogonadotropic hypogonadism, ovarian dysgenesis, premature ovarian failure/insufficiency, ovarian hyperstimulation syndrome, empty follicle syndrome, oocyte maturation defect, fertilization failure, early embryonic arrest, recurrent hydatidiform mole, adrenal disfunction and Mullerian aplasia. Twenty-four gene-disease pairs showed definitive evidence, 36 - strong, 19 - moderate, 81 - limited and 23 - showed no evidence. Here, we provide comprehensive, systematic and timely information on the genetic causes of female infertility. Our classification of genetic causes of female reproductive failure will facilitate the composition of up-to-date guidelines on genetic testing in female reproduction, the development of diagnostic gene panels and the advancement of reproductive decision-making.publishersversionPeer reviewe

Genetic Basis of Early Onset Atrial Fibrillation in Patients without Risk Factors

Funding Information: This research was funded by the Latvian Council of Science, project, “The role of clonal hemato-poiesis of indeterminate potential as a potential driver of cardiovascular diseases and its associ-ation with clinical outcome”, project No. lzp-2021/1-0293. Publisher Copyright: © 2023 by the authors.Background: Atrial fibrillation (AF) is the most common arrhythmia and typically occurs in elderly patients with other cardiovascular and extracardiac diseases. However, up to 15% of AF develops without any related risk factors. Recently, the role of genetic factors has been highlighted in this particular form of AF. Aims: The aims of this study were to determine the prevalence of pathogenic variants in early-onset AF in patients without known disease-related risk factors and to identify any structural cardiac abnormalities in these patients. Materials and Methods: We conducted exome sequencing and interpretation in 54 risk factor-free early-onset AF patients and further validated our findings in a similar AF patient cohort from the UK Biobank. Results: Pathogenic/likely pathogenic variants were found in 13/54 (24%) patients. The variants were identified in cardiomyopathy-related and not arrhythmia-related genes. The majority of the identified variants were TTN gene truncating variants (TTNtvs) (9/13 (69%) patients). We also observed two TTNtvs founder variants in the analysed population—c.13696C>T p.(Gln4566Ter) and c.82240C>T p.(Arg27414Ter). Pathogenic/likely pathogenic variants were found in 9/107 (8%) individuals from an independent similar AF patient cohort from the UK Biobank. In correspondence with our Latvian patients, only variants in cardiomyopathy-associated genes were identified. In five (38%) of the thirteen Latvian patients with pathogenic/likely pathogenic variants, dilation of one or both ventricles was identified on a follow-up cardiac magnetic resonance scan. Conclusions: We observed a high prevalence of pathogenic/likely pathogenic variants in cardiomyopathy-associated genes in patients with risk factor-free early-onset AF. Moreover, our follow-up imaging data indicate that these types of patients are at risk of developing ventricular dilation. Furthermore, we identified two TTNtvs founder variants in our Latvian study population.publishersversionPeer reviewe

Genetic analysis of Latvian Salix alba L. and hybrid populations using nuclear and chloroplast DNA markers

Funding Information: This research was funded within the ERDF project no. 2014/0025/2DP/2.1.1.1.0/ 14APIA/VIAA/101 ?Development of identification technologies for vegetatively propagated short rotation tree species? Publisher Copyright: © SISEF.Latvia is at the northern border of the species range of S. alba L. in Europe, and there has been some debate whether the Latvian populations of S. alba are autochthonous, as this species has long been planted in Latvia as an ornamental tree in gardens, parks and roadsides. In addition, there is increasing interest in the use of several Salix species (including S. alba) as bioenergy crops. Natural S. alba stands throughout Latvia, as well as stands of possibly hybrid origin were analysed using nuclear and chloroplast markers. Our results showed that S. alba populations are probably natural, and that the rate of vegetative reproduction is low, supporting the evidence that Latvia is within the natural range of S. alba. These results provide the basis for the identification of possibly introduced or artificially regenerated stands of S.alba in Latvia. In addition, our results confirm that S. alba hybridises with S. fragilis, and that natural stands including hybrid individuals can be established. The analysis of chloroplast markers indicated that the predominant hybridisation occurs by fertilisation of S. fragilis by S. alba pollen; however, the extent of haplotype sharing between these two species should be further investigated.publishersversionPeer reviewe

Clinical and Genetic Characterisation of Cystic Fibrosis Patients in Latvia : A Twenty-Five-Year Experience

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