Effects of polymorphisms in beta1-adrenoceptor and alpha-subunit of G protein on heart rate and blood pressure during exercise test. The finnish cardiovascular study.

J Appl Physiol vol 100, no 2, pp 507-511, 2006

Mitotic regulation by Polo-like kinase 1 and the Chromosomal Passenger Complex

During mitosis, the duplicated genome must be accurately divided between two daughter cells. Polo-like kinase 1 (Plk1) and Aurora B kinase, together with its binding partners Incenp, Survivin and Borealin (chromosomal passenger complex, CPC), have key roles in coordinating mitotic events. The accuracy of cell division is safeguarded by a signaling cascade termed the mitotic spindle checkpoint (SC), which ensures that chromosomes are not physically separated before correct bipolar attachments have been formed between kinetochores and spindle microtubules (MT). An inhibitory “wait anaphase” signal, which delays chromosome separation (anaphase onset), is created at individual kinetochores and broadcasted throughout the cell in response to lack of kinetochore-microtubule (kMT) attachment or proper interkinetochore tension. It is believed that the fast turnover of SC molecules at kinetochores contributes to the cell’s ability to produce this signal and enables rapid responses to changing cellular conditions. Kinetochores that lack MT attachment and tension express a certain phosphoepitope called the 3F3/2 phosphoepitope, which has been linked to SC signaling. In the experimental part, we investigated the regulation of the 3F3/2 phosphoepitope, analyzed whether CPC molecules turn over at centromeres, and dissected the mitotic roles of the CPC using a microinjection technique that allowed precise temporal control over its function. We found that the kinetochore 3F3/2 phosphoepitope is created by Plk1, and that CPC proteins exhibit constant exchange at centromeres. Moreover, we found that CPC function is necessary in the regulation of chromatid movements and spindle morphology in anaphase. In summary, we identified new functions of key mitotic regulators Plk1 and CPC, and provided insighs into the coordination of mitotic events.

Statistical Inversion Theory in X-ray Tomography

In this thesis the X-ray tomography is discussed from the Bayesian statistical viewpoint. The unknown parameters are assumed random variables and as opposite to traditional methods the solution is obtained as a large sample of the distribution of all possible solutions. As an introduction to tomography an inversion formula for Radon transform is presented on a plane. The vastly used filtered backprojection algorithm is derived. The traditional regularization methods are presented sufficiently to ground the Bayesian approach. The measurements are foton counts at the detector pixels. Thus the assumption of a Poisson distributed measurement error is justified. Often the error is assumed Gaussian, altough the electronic noise caused by the measurement device can change the error structure. The assumption of Gaussian measurement error is discussed. In the thesis the use of different prior distributions in X-ray tomography is discussed. Especially in severely ill-posed problems the use of a suitable prior is the main part of the whole solution process. In the empirical part the presented prior distributions are tested using simulated measurements. The effect of different prior distributions produce are shown in the empirical part of the thesis. The use of prior is shown obligatory in case of severely ill-posed problem.

Molecular genetics of the immotile short tail sperm defect

Hedelmättömyyttä aiheuttavan siittiöiden puolihäntävian molekyyligenetiikka Suomalaisissa Yorkshire karjuissa yleistyi 1990-luvun lopulla autosomaalisesti ja resessiivisesti periytyvä hedelmättömyyttä aiheuttava siittiöiden puolihäntävika (ISTS, immotile short tail sperm). Sairaus aiheuttaa normaalia lyhyemmän ja täysin liikkumattoman siittiön hännän muodostuksen. Muita oireita sairailla karjuilla ei ole havaittu ja emakot ovat oireettomia. Tämän tutkimuksen tarkoituksena oli kartoittaa siittiöiden puolihäntävian aiheuttava geenivirhe ja kehittää DNA-testi markkeri- ja geeniavusteiseen valintaan. Koko genomin kartoituksessa vian aiheuttava alue paikannettiin sian kromosomiin 16. Paikannuksen perusteella kahden geenimerkin haplotyyppi kehitettiin käytettäväksi markkeri-avusteisessa valinnassa. Sairauteen kytkeytyneen alueen hienokartoitusta jatkettiin geenitestin kehittämiseksi kantajadiagnostiikkaan. Vertailevalla kartoituksella oireeseen kytkeytynyt alue paikannettiin 2 cM:n alueelle ihmisen kromosomiin viisi (5p13.2). Tällä alueella sijaitsevia geenejä vastaavista sian sekvensseistä löydetyn muuntelun perusteella voitiin tarkentaa sairauteen kytkeytyneitä haplotyyppejä. Haplotyyppien perusteella puolihäntäoireeseen kytkeytynyt alue rajattiin kahdeksan geenin alueelle ihmisen geenikartalla. Alueelle paikannetun kandidaattigeenin (KPL2) sekvensointi paljasti introniin liittyneen liikkuvan DNA-sekvenssin, Line-1 retroposonin. Tämä retroposoni muuttaa geenin silmikointia siten, että sitä edeltävä eksoni jätetään pois tai myös osa introni- ja inserttisekvenssiä liitetään geenin mRNA tuotteeseen. Molemmissa tapauksissa tuloksena on lyhentynyt KPL2 proteiini. Tähän retroposoni-inserttiin perustuva geenitesti on ollut sianjalostajien käytössä vuodesta 2006. KPL2 geenin ilmenemisen tarkastelu sialla ja hiirellä paljasti useita kudosspesifisiä silmikointimuotoja. KPL2 geenin pitkä muoto ilmenee pääasiassa vain kiveksessä, mikä selittää geenivirheen aiheuttamat erityisesti siittiön kehitykseen liittyvät oireet. KPL2 proteiinin ilmeneminen hiiren siittiön hännän kehityksen aikana ja mahdollinen yhteistoiminta IFT20 proteiinin kanssa viittaavat tehtävään proteiinien kuljetuksessa siittiön häntään. Mahdollisen kuljetustehtävän lisäksi KPL2 saattaa toimia myös siittiön hännän rakenneosana, koska se paikannettiin valmiin siittiön hännän keskiosaan. Lisäksi KPL2 proteiini saattaa myös toimia Golgin laitteessa sekä Sertolin solujen ja spermatidien liitoksissa, mutta nämä havainnot kuitenkin vaativat lisätutkimuksia. Tämän tutkimuksen tulokset osoittavat, että KPL2 geeni on tärkeä siittiön hännän kehitykselle ja sen rakennemuutos aiheuttaa siittiöiden puolihäntäoireen suomalaisilla Yorkshire karjuilla. KPL2 proteiinin ilmeneminen ja paikannus siittiön kehityksen aikana antaa viitteitä proteiinin toiminnasta. Koska KPL2 geenisekvenssi on erittäin konservoitunut, nämä tulokset tuovat uutta tietoa kaikkien nisäkkäiden siittiöiden kehitykseen ja urosten hedelmättömyyteen syihin.

Inversion and assimilation methods with applications in geophysical remote sensing

Stratospheric ozone can be measured accurately using a limb scatter remote sensing technique at the UV-visible spectral region of solar light. The advantages of this technique includes a good vertical resolution and a good daytime coverage of the measurements. In addition to ozone, UV-visible limb scatter measurements contain information about NO2, NO3, OClO, BrO and aerosols. There are currently several satellite instruments continuously scanning the atmosphere and measuring the UVvisible region of the spectrum, e.g., the Optical Spectrograph and Infrared Imager System (OSIRIS) launched on the Odin satellite in February 2001, and the Scanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY (SCIAMACHY) launched on Envisat in March 2002. Envisat also carries the Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument, which also measures limb-scattered sunlight under bright limb occultation conditions. These conditions occur during daytime occultation measurements. The global coverage of the satellite measurements is far better than any other ozone measurement technique, but still the measurements are sparse in the spatial domain. Measurements are also repeated relatively rarely over a certain area, and the composition of the Earth’s atmosphere changes dynamically. Assimilation methods are therefore needed in order to combine the information of the measurements with the atmospheric model. In recent years, the focus of assimilation algorithm research has turned towards filtering methods. The traditional Extended Kalman filter (EKF) method takes into account not only the uncertainty of the measurements, but also the uncertainty of the evolution model of the system. However, the computational cost of full blown EKF increases rapidly as the number of the model parameters increases. Therefore the EKF method cannot be applied directly to the stratospheric ozone assimilation problem. The work in this thesis is devoted to the development of inversion methods for satellite instruments and the development of assimilation methods used with atmospheric models.

Nasopharyngeal colonization by pathogenic bacteria: effect of polymorphisms in innate immune genes of young children

Nasopharyngeal bacteria can asymptomatically colonize the nasopharynx of infants and young children but are also associated with the development of respiratory infections and diseases. Such nasopharyngeal bacteria include Streptococcus pneumoniae, Moraxella catarrhalis, Haemophilus influenzae and Staphylococcus aureus. The host defense against invading pathogens is largely relies germline-encoded pattern recognition receptors (PRR), which are expressed on the cells of innate immunity, and different cytokines. These include toll-like receptors (TLR), mannose-binding lectin (MBL) and different cytokines such as IL-17A. Single nucleotide polymorphisms (SNP) in these receptors and cytokines have been reported. The aim of this study was to investigate genetic polymorphisms in the genes for TLR2, 3 and 4, MBL as well as for IL-17A and their associations with nasopharyngeal pathogenic bacterial colonization during a two-year follow-up. The study revealed that polymorphisms in TLRs, MBL2 and IL17A are associated with the nasopharyngeal bacterial colonization in young children. Healthy young (2.6 months of age) children with variant types of MBL2, TLR2 R753Q or TLR4 D299G had an increased risk to be colonized by S. pneumonia, S. aureus or M. catarrhalis, respectively. Moreover, variant types of MBL2 in healthy children with might facilitate human rhinovirus (HRV)-induced S. pneumoniae colonization at 2.6 months of age. The polymorphism of TLR4 D299G was shown to be associated with M. catarrhalis colonization throughout the whole two-year follow-up (2.6, 13 and 24 months of age) and also with the bacterial load of this pathogen. Also, the polymorphism of IL17A G152A was shown to be associated with increased risk to be colonized by S. pneumoniae at 13 and 24 months of age. Furthermore, the results suggest that IL17A G152A has an effect on production of serum IL-17A already at young age. In conclusion, the results of this study indicate that polymorphisms in the key PRRs and IL17A seem to play an important role to colonization of S. pneumoniae, M. catarrhalis, and S. aureus in healthy young Finnish children. The nasopharyngeal colonization by these pathogenic bacteria may further promote the development of respiratory infections and may be related to development of asthma and allergy in the later life of children. These findings offer a possible explanation why some children have more respiratory infections than other children and provide a rational basis for future studies in this field.

Pertussis: infection, vaccination and gene polymorphisms

Pertussis or whooping cough is a human respiratory tract infection and a vaccine-preventable disease that is caused by Bordetella pertussis bacteria. Pertussis vaccination has been part of the Finnish national vaccine program since 1952. Despite extensive vaccinations, the incidence of pertussis has increased in many countries during the last decades. Large epidemics have been observed also in countries with high vaccine coverage. Inter-individual variation in immune responses is always encountered after vaccination. Low vaccine responses may cause vulnerability to pertussis even straight after vaccination. Reasons for low responses are not fully understood. The innate immune system is responsible for the initial recognition of pathogens and vaccine antigens. The role of innate immunity on pertussis immunity has not been thoroughly investigated. Mannose-binding lectin (MBL) and toll-like receptor 4 (TLR4) are important molecules of the innate immune system and in the recognition of pathogens. Cytokines form a signaling network that have a notable role in immune responses after infections as well as after vaccinations. Single nucleotide polymorphism (SNP) is common in genes encoding these molecules and the polymorphisms have been reported to affect vaccine response after viral and bacterial vaccines. This study investigated the gene polymorphisms of MBL2, TLR4 and interleukin (IL)-10 promoter and their association with vaccine responses after acellular pertussis (aP) vaccination in Finnish adolescents and infants. Cell-mediated immune responses were investigated ten years after the previous pertussis vaccinations in young adults. In addition, the role of MBL deficiency in pertussis infection susceptibility was evaluated. The results of this study show that subjects with TLR4 polymorphism had lower antibody production and persistence after aP vaccination compared with normal allele. A specific SNP in the TLR4 gene was associated with decreased antibody responses and persistence in adolescents after aP booster vaccination. Cell-mediated immune responses were partly detected ten years after the previous vaccination; booster vaccine clearly enhanced the responses. In addition, subjects with IL-10 polymorphism had altered cell-mediated immune responses. MBL deficiency was found to be more frequent in pertussis patients than healthy controls but the polymorphism of MBL2 was not associated with antibody responses after acellular pertussis vaccination. The novel finding of this study was that genetic variation in the innate immune system seems to play a role in altered pertussis vaccine responses as well as in pertussis infection. These new findings enlighten the mechanisms behind the low responses after pertussis vaccination and help to predict risk factors related to this phenomenon.