Browsing by Title

Objectives Fatigue is a major factor affecting driving performance and traffic accident risk. Driving conditions influence how people experience fatigue while driving. Driving in demanding conditions may increase vigilance in tired drivers; however, it may also increase cognitive load and become an additional source of fatigue. The current study investigated how driving on a slippery road interacts with fatigue caused by sleep deprivation and how it influences driving performance. Methods Twelve male participants (aged 19–21) drove 52.5 km in a driving simulator in four different conditions (day vs night and dry vs slippery road). Subjective sleep-related fatigue was measured with the Karolinska Sleepiness Scale and physiological fatigue in blink durations with electro-oculography. Three measures were used for driver performance: standard deviation of lateral position, mean steering wheel movement amplitude and mean steering wheel movement peak velocity. After each driving session, participants negotiated a cone track. The success rate for this task was analysed separately. Results Driving on slippery roads improved performance in all three performance metrics in sleep-deprived drivers. The three-way interaction between driver condition, road condition and time-on-task was significant for subjective sleep-related fatigue but not for performance. Sleep-deprived drivers became increasingly sleepy over time when driving in slippery conditions; however, this did not negatively affect their performance. Conclusions Driving in demanding weather conditions can increase the fatigue experienced by drivers; however, this change may not be initially detectable in performance. Large individual variability in response to both fatigue and driving conditions requires further research.

Objectives – Neonatal hyperbilirubinemia (HB), also referred to as neonatal jaundice, can alter child’s neurodevelopment, and thus significantly increase infant’s risk for severe neurological disability. Although the majority of neonatal HB cases benign, there are several cases where bilirubin levels grow alarmingly and remain elevated, eventually causing permanent physical harm and frequently altering the development of central nervous system. Research on the long-term effects of HB has been lacking: the follow-ups have been relative short, and there are not many studies focusing on how neonatal HB might influence neurocognition in later adulthood (> 30 year of age). The aim of this study is to further investigate the association between neonatal HB and later cognitive performance in adulthood by using data from over 40-year-long Finnish follow-up study. Methods – In a longitudinal prospective study, data were collected from 125 subject who had experienced neonatal HB and from 77 controls. Cognitive performance was assessed at age of 40 by using various previously validated methods designed to assess executive function and attention, memory, verbal functions, and visuo-perceptual functions. Four factors were formed for neuropsychological variables: Cognitive flexibility, Visual memory and perception, Verbal memory, and Reading. In addition, all subjects had performed WAIS-IV assessments. Data from these assessments were used to create four new factors – Verbal comprehension, Working Memory, Perceptual Reasoning, and Processing Speed – reflecting different cognitive areas. Also, Full-Scale Intelligence Quotient (FSIQ) was included. Linear regression analyses were used to assess the relation between HB-classification and neuropsychological variables. Differences between the groups were further studied by pair-wise comparisons using t-test, after which Mann–Whitney-U test was used to take into account moderate to highly skewed distributions of the variables. Effects of different HB levels on later neurocognition was studied by using linear regression, where sex, mother’s age at birth, and mother’s education level were controlled. Results – Neonatal HB was associated with slower performance in Cognitive Flexibility, and with lower performance in Perceptual Reasoning and in FSIQ. Highest measured neonatal bilirubin levels within HB group had a linear effect on Verbal Comprehension at age of 40; however, the effect was not found in other cognitive domains. Conclusions – Neonatal HB has effect on performance in FSIQ at age of 40 years. In addition, it was associated with both poorer Perceptual Reasoning and slower Cognitive Flexibility. Results might be due to perceptual reasoning’s high vulnerability to neuronal damage and to difficulty of compensating perceptual biological limitations with learning. Since the measured neonatal bilirubin levels within HB group was associated only with lower performance in Verbal Reasoning in this study, it could be concluded that after reaching the inclusion criteria the excess level of bilirubin was no longer significant influence on severity of the outcome.

Mitochondrial disorders form a heterogenous disorder group with symptoms widely varying. They exist because of mutations in mtDNA or nuclear DNA, which encode mitochondrial proteins or regulate their functions. Because mitochondria are present in almost all cells in the human body, symptoms of mitochondrial disorders vary and can manifest in all tissues. The most common manifestation of mitochondrial disorders in adult patients is mitochondrial myopathy, which leads to muscle weakness and fatigue. Pathological findings of mitochondrial myopathy include changed activities in mitochondrial respiratory chain, centrally located nuclei and increased expressions of genes related to integrated mitochondrial stress responses. One of the neurological symptoms of mitochondrial disorders is parkinsonism. Parkinson’s disease is the world’s second most common neurodegenerative disease. Its clinical symptoms include bradykinesia and resting tremor, and its pathological hallmarks include alphasynuclein protein accumulations and loss of dopaminergic neurons in substantia nigra. Despite being described first time over a hundred years ago, the mechanisms behind Parkinson’s disease are still unclear. However, several genes have been associated with Parkinson’s disease. PINK1, encoding PINK1 protein, and PRKN, encoding Parkin protein, are genes, which mutations have been associated to early onset Parkinson’s disease. According to suggested theories, their normal physiological functions include mediating a special form of autophagy, mitophagy, and suppressing mitochondrial antigen presentation. It has been suggested that loss of PINK1 or PRKN could disrupt mitophagy, leading to accumulation of dysfunctional mitochondria in the cell, disrupting its homeostasis and leading to its death. This PINK1/Parkin-mediated mitophagy and its disruption could explain the death of dopaminergic neurons. In addition, loss of PINK1 and Parkin could also activate mitochondrial antigen presentation, which activates autoimmune response and destroys dopaminergic neurons presenting mitochondrial antigens. This suggests that Parkinson’s disease could have autoimmune-like mechanisms behind it. Together, these theories could explain the onset of Parkinson’s disease when PINK1 or PRKN are absent. In this thesis, the main objective was to study, how loss of PINK1 and PRKN would affect on muscle of aged mouse. More precisely, the effects of these genes to mitochondrial homeostasis were studied in terms of mitophagy and mitochondrial respiratory chain activity. In addition, it was studied, if these genes could induce mitochondrial myopathies or affect to existing condition by studying typical signs associated with mitochondrial myopathy, such as changes in activity of mitochondrial respiratory chain subunits, location of nuclei in muscle, changes in lipid and glycogen accumulation and expressions of genes associated to mitochondrial integrated stress responses. Finally, the theory of mitochondrial antigen presentation was studied. The results of this thesis provide more evidence to theory of PINK1/Parkin mediated mitophagy, but also suggest, that these proteins could be compensated. Based on the results, PINK1 seems to be more crucial for healthy muscle, but in already existing mitochondrial myopathy, loss of either of PINK1 or Parkin seems to improve the condition. According to this thesis, both PINK1 and Parkin, and mitophagy seem to be crucial in induction of mitochondrial myopathy. Despite more evidence is now provided to support the roles of PINK1 and Parkin in mitochondrial maintenance, their roles in mitochondrial antigen presentation did not receive support from this thesis.

In this master’s thesis, in vitro neuromuscular junction (NMJ) model was set up using microfluidic devices. Additionally, the effect of R878H/R878H mutation in MCM3AP gene that causes an early-onset peripheral neuropathy on NMJ formation and maintenance was studied. To study human NMJs that significantly differ from other mammal NMJs is challenging and new models to study the function of these complex and highly specialized structures are needed. Induced pluripotent stem cells (iPSC) and motor neurons were characterized with gene expression studies using qRT-PCR and with immunocytochemistry studies using commonly known markers for pluripotency and motor neurons. NMJs were studied in 2D co-cultures and with microfluidic devices. Gene expression studies were conducted from 2D co-cultures and co-cultures in microfluidic devices provided detailed information of the localization and morphology of NMJs. Expression of essential genes for NMJ formation together with immunocytochemistry results with alpha-bungarotoxin (BTX) staining showed that NMJs were formed in both control and R878H/R878H mutant cell line co-cultures. There was a trend of lower gene expression levels of NMJ essential genes in the R878H/R878H mutant line compared to the control line and also immunocytochemistry results indicated impairment in NMJ formation in the mutant line, but further studies are needed to validate the effect of R878H/R878H mutation on the NMJ formation. In future, functional studies could be conducted to investigate whether these NMJs are functional and the information from the motor neuron terminal is conveyed to the muscle membrane.

ABSTRACT The insular cortex (insula) was recently identified as key neuroanatomical substrate underlying the neurocircuitry of addiction, and a rapidly growing body of evidence ascribe it numerous functional roles in addiction-related behaviours. Yet, neural system interactions through which the insula establishes its roles remain largely unknown. Identifying these critical circuits lays the foundation for the successful advancement of addiction research and therapeutics targeting this brain area. To this end, the current set of experiments aimed to characterize the efferent connections of the anterior insula (AI) to the nucleus accumbens (NAc; AI --> NAc) and the basolateral amygdala (BLA; AI --> BLA); two subcortical regions, which are heavily implicated in reward, motivational and emotional processing. By chemogenetically manipulating the activity of these circuits, their functional roles in modulating alcohol self-administration in alcohol-preferring AA (Alko, Alcohol) rats were examined. While AI --> NAc projections were recently verified anatomically, we first confirmed connectivity of AI --> BLA by injecting a viral retrograde tracer encoding enhanced green fluorescent protein (eGFP) unilaterally into the BLA of AA rats. The functional role of the AI --> BLA and AI --> NAc pathways in mediating alcohol drinking was examined by using the intermittent two-bottle choice paradigm in combination with a Cre-dependent DREADD (Designer Receptor Exclusively Activated by Designer Drug) approach. Projection-specific DREADD expression was achieved by injecting a Cre-dependent viral DREADD vector into the AI while a retrograde virus carrying Cre-recombinase was injected either into the BLA or NAc. CNO-induced activation of the AI --> NAc circuit resulted in a significant increase in alcohol consumption. Curiously, silencing these projections had no effect, either reflecting the intrinsic nature of the NAc circuitry or limitations inherent in the technical approach. Neither chemogenetic silencing nor activation of the AI --> BLA circuit altered alcohol consumption. Furthermore, no changes were observed in the control groups upon systemic CNO administration, indicating no unspecific CNO effects. The current body of work provides new insights into the insula-related circuitry showing that the activity of the AI --> NAc circuit drives alcohol self-administration, whereas AI --> BLA projections are not recruited during this behaviour. This indicates that the insular-striatal circuit belongs to the forebrain neurocircuitry underlying alcohol drinking. The study should be pursued by characterizing the neuronal populations and specific neuronal receptor populations that are involved in the AI --> NAc circuit. Future research should examine other insular-centred circuits that may govern alcohol drinking.

Ihmisen perintötekijät eli geenit koostuvat eksoneista ja introneista. Eksonit sisältävät ohjeet valkuaisaineiden, proteiinien, valmistamiseksi. Yhden henkilön kaikista eksoneista käytetään yhdessä termiä eksomi. Tämän eksomin rakenne eli emäsjärjestys on nykyisin mahdollista selvittää erityisillä sekvensointilaitteilla. Muutokset tai virheet eksomissa, eli yhdessä tai useammassa eksonissa, voivat johtaa tiettyjen proteiinien puuttumiseen tai muodostumiseen väärin, mikä aiheuttaa sairauden. Tämän vuoksi eksomin rakenteen selvittäminen eli eksomisekvensointi on tullut käyttöön potilaiden diagnostiikkaan. Kyseessä on kuitenkin edelleen niin vaativa ja kallis tutkimus, että sen hyödyntämistä edeltävät usein muut lääketieteelliset tutkimukset. Eksomisekvensoinnin jälkeen vaaditaan vielä saatujen tietojen tulkitsemista suhteessa potilaaseen ja taustaväestöön. Esimerkiksi eräät muutokset eksomissa ovat niin yleisiä tietyissä väestöissä, että voidaan olettaa, etteivät ne aiheuta sairauksia. Eksomin rakenteen selvittämistä voidaan diagnostiikan lisäksi hyödyntää tutkimuksissa etsittäessä uusia, tuntemattomia perimän muutoksia sairauksien tai tautien taustalla. Tässä tutkimuksessa kolmen potilaan eksomisekvensointituloksista suodatettiin populaatiotietoja sekä kyseisten potilaiden kliinistä kuvaa hyödyntäen todennäköiset kandidaattigeenit. Saatujen kandidaattigeenien avulla voidaan diagnostiikkaa kohdistaa tarkemmin esimerkiksi tiettyyn aineenvaihduntareittiin. Eksomisekvensointia voidaan luontevasti verrata koko perimän eli genomin sekvensointiin tai ennalta valikoituun geenijoukkoon kohdistuvaan paneelisekvensointiin. Koko genomiin nähden on eksomin tutkiminen selkeästi nopeampaa ja halvempaa. Toisaalta osa sairauksista johtuu muutoksista eksonien ulkopuolissa alueissa, joiden havaitsemiseen genomisekvensointi soveltuu. Paneeleita käytettäessä on etukäteen tiedettävä, mihin geeneihin paneeli kohdistetaan. Tällöin ei myöskään löydetä mahdollisia uusia tauteja aiheuttavia perimän muutoksia.

Mycobacterium tuberculosiksen aiheuttama tuberkuloosi on yksi yleisimmistä kuolemaan johtavista sairauksista kehitysmaissa. M. tuberculosis-bakteerin tiedetään kykenevän väistämään potilaan immuunipuolustusta ja hyödyntämään makrofagien sekä muiden puolustussolujen ominaisuuksia. M. tuberculosis kykenee lisääntymään makrofagien sisällä. Eksosomit ovat solunulkoisia rakkuloita, joita kaikki solut erittävät. Eksosomeilla tiedetään olevan myös immunomodulatorisia vaikutuksia. Tutkimuksen tarkoituksena oli kehittää in vivo-malli eksosomien immunomodulatoristen ominaisuuksien mallintamiseen seeprakaloissa, hyödyntämällä seeprakalojen omaa Mycobacterium marinum-patogeeniä. Tutkimuksessa käytettiin ihmisen monosyyttilinjan soluja (THP-1), lämpötapettuja M. marinum-bakteereja ja seeprakalojen poikasia. THP-1 -soluja käsiteltiin lämpötapetuilla M. marinum bakteereilla viidellä eri bakteerikonsentraatiolla. Lisäksi tutkimuksessa oli yksi bakteereilla käsittelemätön THP-1 -soluviljelmä. Kaikista THP-1 -soluviljelmistä eristettiin ultrasentrifugaatiolla kyseisten solujen tuottamia eksosomeja. Eristettyä eksosomeja mikroinjektoitiin kuorittujen seeprakalan poikasten ruskuaispussin blood circulation valley -suoneen, jotta nähtäisiin aiheuttavatko ne muutoksia kalojen tulehduksenvälittäjäaineiden geenien ilmentymisessä eli geeniekspressiossa. Noin puolen vuorokauden jälkeen kalaryhmästä poistettiin kuolleet yksilöt ja elossa olevat kerättiin talteen RNA-eristystä varten. Eristetty RNA käännettiin DNA:ksi ja reaaliaikaisella polymeraasiketjureaktiolla, qPCR:llä, mitattiin kohdegeenien ekspressioita. Tutkimuksessa havaittiin valittujen tulehdusvälittäjäaineiden geenien ilmentymisen lisääntymistä seeprakaloissa. Geenin ilmentymstaso oli sitä suurempi, mitä suuremmalle bakteerimäärälle THP-1 -solut oli altistettu ennen eksosomien eristystä. Kaikkein korkeimmat tulehdusvälittäjäaineiden geeniekspressiotasot nähtiin altistamattomien solujen eksosomeilla injektoitujen kalojen ryhmissä. Kontrolliksi valitussa geenissä ei havaittu vastaavaa geeniekspression kasvua. Näiden tutkimustulosten perusteella lämpötapetulla M. marinumilla käsiteltyjen THP-1 -solujen eksosomeilla näyttäisi olevan kyky aiheuttaa samankaltaisia muutoksia tulehdusvälittäjäaineiden geeniekspressiossa kuin seeprakalojen suoralla M. marinum infektiolla. Tulosten vahvistamiseen tarvitaan vielä lisätutkimuksia.

Objectives. Can individual differences in the way people manage their own lives (life management) be explained from the perspective of life history theory? Understanding these differences is important since life management has a great impact on the wellbeing of people. Life history theory has already been proven to explain many individual differences in the human cognition; this study aimed to expand this field of knowledge. Life history theory states, that the early-life environment of an individual shapes her life history strategies, adapting her to her environment. The events that serve as reminders of mortality in the environment of an individual (mortality cues) were hypothesised to activate different life history strategies in individuals with different childhood environments. This was hypothesised to be reflected as differences in life management. The study also sought to find out, if the observation that people can react differently to a similar mortality cue can be explained by their strategy's impact on their locus of control. Methods. The data used in this study came from the Cardiovascular Risk in Young Finns Study. The relationship between early-life environment (childhood socioeconomic status, SES) and life management (the Self-directedness scale in the Temperament and Character Inventory and two items concerning coping) was explored in the study. Regression analysis was used to analyse whether mortality cues moderated the relationship between SES and self-directedness. Logistic regression analysis was used to analyse whether they moderated the relationship between SES and coping. Sample size was 2 103 for analyses concerning self-directedness (mean age = 31.48 years) and 773 for those concerning coping (mean age = 20.66 years). Results and conclusions. Individuals with lower childhood SES felt that things outside their control were influencing their life more than did those with higher childhood SES. Lower SES was also connected with lower self-directedness in general. The tendency to use one way of coping over another after facing the death of a friend or a family member seemed to depend on childhood SES. Individuals with lower childhood SES used more approach coping; those with higher childhood SES used more avoidance coping. Life history theory seems to be a relevant scientific framework for studying individual differences in life management. Differences in life management might help to understand why people with different backgrounds might react differently to a similar mortality cue. However, no interaction effect on life management was found between the other mortality cues used in the study and childhood SES. Sporadic incidences that are a natural part of life do not seem to activate life history strategies permanently. It is advised then, that especially when the activation of life history strategies is explored using an experimental study design, the results should be interpreted keeping in mind the possibility that single cues might only activate strategies temporarily.

Johdanto Tämän tutkielman tavoitteena oli selvittää nuorten aikuisten terveydellisen ja sosiodemografisen elämäntilanteen yhteyttä ajankohtaiseen psyykkiseen kuormitukseen. Terveydellisen elämäntilanteen osalta tarkastelimme koettua terveyttä, elämäntyytyväisyyttä, tyytyväisyyttä parisuhteeseen sekä alkoholin haitallista käyttöä. Sosiodemografisista tekijöistä tarkastelukohteinamme olivat sukupuoli, koulutustaso, työttömyys sekä asuinpaikan koko. Psyykkistä kuormitusta mitattiin GHQ-12 -kyselyllä. Aineisto ja menetelmät Aineistonamme oli kansallinen kaksosten ja heidän perheidensä terveydentilaa ja terveyskäyttäytymistä kartoittava pitkittäinen syntymäkohorttitutkimus (FinnTwin16), joka käsittää vuosina 1975-1979 syntyneet suomalaiset kaksoset. Tässä tutkimuksessa keskityimme FinnTwin16 -tutkimusaineiston osaan, joka kerättin kyselylomakkeella kaksosten ollessa 22-27 vuoden iässä. Kyselylomakkeen osista keskityimme koettua terveyttä, elämäntyytyväisyyttä, parisuhteessa koettua tyytyväisyyttä, alkoholin haitallista käyttöä, työttömyyttä, koulutustasoa ja asuinpaikan kokoa käsitteleviin osiin. Tulokset Havaitsimme, että hyvä koettu terveys, elämäntyytyväisyys ja tyytyväisyys parisuhteeseen olivat kaikki käänteisesti yhteydessä psyykkiseen kuormitukseen sekä miehillä että naisilla. Alkoholin haitallinen käyttö puolestaan oli suoraan yhteydessä psyykkiseen kuormitukseen kaikilla tutkittavilla. Havaitsimme myös, että naisilla psyykkinen kuormitus oli yleisesti ottaen suurempaa kuin miehillä. Työttömyys puolestaan oli yhteydessä suurempaan psyykkiseen kuormitukseen ainoastaan miehillä. Koulutustasolla ja asuinpaikan koolla emme tässä tutkimuksessa havainneet yhteyttä psyykkiseen kuormitukseen. Pohdinta Tässä tutkimuksessa teimme analyysit muuttujakohtaisesti ja poikkileikkausasetelmassa. Jatkossa useamman muuttujan käsittävät analyysit tai psyykkisen kuormituksen tarkastelu demografisesti vakioiduin osajoukoin olisi tärkeää ilmiöiden tarkempien ajallisten yhteyksien ymmärtämiseksi.

Objectives. Perception of auditory pitch can be divided in to two dimensions of height and chroma. Tones of the same chroma, one or more octave intervals apart, sound similar. The octave interval is defined as the doubling of a tones fundamental frequency. However, in humans the perceptual octave slightly exceeds its mathematical counterpart. The objective of this study was to clarify the neural underpinnings responsible for the subjective experience of chroma and the enlarged octave. Methods. During all experiments adapter tones followed by probing tones were sequentially presented to participants (n=18). Adapter tones were used to activate neural populations and probing tones were used for measuring amplitude reductions (adaptation) in EEG derived event related potentials (ERPs) signalling overlapping neural population responses to adapter and probing tones. Participants were divided in to two groups with either sine tones or complex tones as adapters. 7 pitch separations between adapter and probe were used. Differences between different interval ERPs and effects of musical proficiency in both groups were analysed with mixed repeated measures analyses of variance. Measurements were fitted to a combined sinusoidal and linear pitch helix function. Source magnitude estimation was calculated to investigate hemispheric asymmetry. Results and conclusions. There was greater neural overlap between tones sharing the same chroma compared to tones one semitone apart. Periodicity independent adaptation indicated that pitch is not co-represented with stimulus spectrum in the human auditory cortex. Source magnitude analyses showed that N1 responses were stronger on the right auditory cortex. P2 amplitude showed stronger adaptation to enlarged octave intervals in comparison to exact mathematical octave intervals.