Browsing by Subject "Physiology"

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  • Albinus, Bernhard Siegfried (Leidae, 1754)
  • Rossi, Elina (Helsingfors universitet, 2006)
    The purpose of my thesis was to find out how Finnish dung beetles find their most important resource, dung. I tried to establish the most important sense for finding dung, to which part or parts of the scent dung beetles react to and how sensitive their ability to detect dung is. Dung beetles are an important part of the ecosystem and a long used model for population study. They are an interesting target for sensory research because their resource is both patchy and short-lived. Because of these aspects dung beetles have to locate dung very quickly and efficiently. I used dung beetles belonging to family Aphodiidae (Scarabaeoidea Laparosticti) that I collected from cow pastures in Viikki using pitfall traps. To track down how dung beetles approach dung I observed their approaching behaviour in the wild. To figure out the importance of sight and smell I eliminated one sense at a time and observed how it affected beetles' behaviour. I eliminated olfaction by cutting off antennas and sight by painting the beetles' eyes. To find out chemical attractants in question I first analyzed smelly, volatile organic compounds in cow dung and then offered them as bait alone and in different combinations in pitfall traps in the wild. I also tried to establish the sensitivity of olfaction by offering different amounts of cow dung in a long windless corridor to dung beetles. I noticed that dung beetles approach dung by flying low in headwind. Part of the beetles approached flying in a narrowing zigzag-pattern while others landed occasionally to orientate and approached in small spurts. Eliminating olfaction effectively prevented dung beetles from finding dung whilst blinded individuals performed as well as control beetles. From all the chemical components I used, only butane acid attracted some dung beetles. A combination of chemicals is what presumably attracts dung beetles best.
  • Komulainen, Anne (Helsingfors universitet, 2013)
    Pulmonary arterial hypertension (PAH) is a progressive and devastating disease with poorly understood pathogenesis. It is characterized by abnormal remodelling of pulmonary vasculature due to uncontrolled apoptosis and proliferation of endothelial (ECs) and smooth muscle cells (SMCs) in vascular wall. In severe PAH pulmonary ECs exhibit hyperproliferative and apoptosis resistant phenotype contributing to the formation of neointima and development of plexiformic lesions. Structural changes promote occlusion of vascular lumen, and thus, increase in pulmonary vascular resistance. To date we lack efficient therapy to prevent vascular remodelling and restore normal vascular function in PAH. Purinergic signalling is potential modulator of pulmonary vascular homeostasis. It comprises of extracellular nucleotides, such as ATP, which signal through their receptors on cell membrane. Ectoenzymes with nucleotide hydrolyzing activity have an essential part in controlling homeostasis and physiologic concentration of extracellular nucleotides. Ectoenzyme CD39 plays a crucial role in dephosphorylating ATP, which is a known mediator of inflammation, angiogenesis, thrombosis and vasoconstriction according to previous research. Aims of this project were to study the role of extracellular ATP in pulmonary endothelial dysfunction during PAH pathogenesis. The goal was to evaluate the significance of ATPases, such as CD39, in the disease process and to identify significant ATP receptors on pulmonary ECs. We utilized a previously unused strategy to monitor ATPase activity in vivo in pulmonary endothelium of rats with PAH. With this strategy we could identify changes in a time-line manner. Our results indicate that ATPase activity is significantly attenuated in ECs during disease process. Similar finding was also observed in human pulmonary EC isolated from PAH patients suggesting that loss of ATPase activity mediated increase of extracellular ATP could play a role in disease pathogenesis. Our in vitro experiments reveal that loss-of CD39 in human pulmonary ECs leads to an apoptosis resistant and hyperproliferative phenotype. We also identify that purinergic receptor P2Y11 is a critical mediator of ATP responses in these ECs. Suppression of ATP mediated P2Y11 response in apoptosis resistant PAH patient ECs restores normal EC phenotype and thus, suggests a novel therapeutic strategy for pulmonary occlusive vasculopathy.
  • Haller, Albert von (Albertus de)(Albrecht) (Lausannae, 1782)
  • Lehtikuja, Henna (Helsingin yliopisto, 2018)
    In our study, we examined the effects of early-life stress on sleep, depressive behaviour and neurophysiological factors common for depression and sleep disturbances. As a model for early-life stress we used cross-fostered (CF) adolescent and adult, male and female rats. In spontaneous sleep, we found an increase in NREM and REM time in light period and an increased number of REM onsets in light and dark period in CF group. Baseline adenosine expression and BDNF levels in basal forebrain were decreased in CF animals. In the behavioural tests there were no detectable differences, nor in recovery sleep. This thesis will concentrate on the scientific background of the project, further discuss the findings in our study and demonstrate the writer’s personal role in the project.
  • Kajos, Miina (Helsingfors universitet, 2005)
    1-Bentsyylipiperatsiini (BZP) on viime vuosina laittomille markkinoille ilmaantunut ns. design-huume, jonka on todettu muistuttavan vaikutuksiltaan amfetamiinia. Sen myynti tapahtuu tyypillisesti tanssiklubeilla ja Internetin välityksellä. Esimerkiksi Yhdysvalloissa BZP on luokiteltu laittomaksi, mutta suurimmassa osassa maailmaa aine on huumausainelainsäädännön ulkopuolella. Suomesta ainetta takavarikoitiin neljästi vuosina 2002-04. Tässä tutkimuksessa selvitetään ehdollistetun paikkahakuisuuskokeen avulla, onko BZP:lla palkitsevia ominaisuuksia. Kokeessa koe-eläimet opetetaan yhdistämään tutkittavan aineen vaikutukset tiettyyn ympäristöön, ja mikäli eläin alkaa tämän jälkeen suosia ympäristöä, eli aine aiheuttaa paikkahakuisuutta, tulkitaan aineella olevan palkitsevia ominaisuuksia. Palkitsevien ominaisuuksien katsotaan heijastavan aineen riippuvuuspotentiaalia, sillä useimpien ihmisten väärinkäyttämien aineiden on todettu aiheuttavan ehdollistettua paikkahakuisuutta. BZP:n todettiin aiheuttavan rotille ehdollistettua paikkahakuisuutta annosriippuvaisesti, minkä jälkeen selvitettiin reseptorisalpaajien avulla dopamiinireseptorien merkitystä paikkahakuisuuden synnylle. Dopamiini-1-, eli D1-reseptorisalpaus esti paikkahakuisuuden, kun taas D2-salpauksella ei ollut siihen vaikutusta. Kokeiden perusteella BZP:lla on palkitsevia vaikutuksia, jotka välittyvät D1-, mutteivät D2-reseptorien kautta. Tulokset viittaavat BZP:lla olevan väärinkäyttö- ja riippuvuuspotentiaalia, minkä vuoksi olisi perusteltua, että se kuuluisi lainsäädännöllisesti samaan kategoriaan mm. amfetamiinin kanssa.
  • Äikäs, Lauri (Helsingin yliopisto, 2021)
    Abstract Introduction: Atherosclerotic cardiovascular diseases (ASCVD) cause the biggest burden on our healthcare system and cause most premature deaths. Risk for ASCVD can be lowered by lifestyle choices and medication, as well as several therapeutics such as ethyl eicosapentaenoic acid (E-EPA) supplementation. Here we aimed to investigate the effect of EEPA intervention on known ASCVD risk factors including circulating lipoprotein levels as well as low-density lipoprotein (LDL) aggregation susceptibility, a new independent risk factor for ASCVD. Study design: A study group of 39 healthy men and women participated in a 4-week long dietary supplement trial with 3.9 g/day of E-EPA. A dose of 75 µg/day of vitamin D was included in the E-EPA capsules. Blood samples were drawn before the trial, at weeks 1 and 4 of the intervention and 1 week after the intervention. The study was an open design where participants’ own baseline measurements were used to measure changes. Outcomes: The mean plasma cholesterol concentration was reduced from 3.8 mmol/l to 3.6 mmol/l (p=0.0038 one-way ANOVA) after one week of E-EPA supplementation and remained the same until the end of study period. This change was followed by a change in plasma LDL (p=0.0028 one-way ANOVA) and triglyceride (p=0.0004 one-way ANOVA) concentrations after four week and one week of E-EPA supplementation, respectively. Vitamin D levels increased on average by 18%, showcasing a lower relative response than seen in other vitamin D trials, which can be attributed to high effective baseline concentrations of vitamin D in our study group and the related negative feedback system. LDL aggregation susceptibility did not significantly change in the entire group. However, we discovered that the change in LDL aggregation susceptibility correlated negatively ( = -0.451, p = 0.0039) with the baseline LDL aggregation susceptibility. Thus, LDL aggregation decreased in participants having aggregation-prone LDL at baseline. This finding highlights a possibility that participants with higher LDL aggregation susceptibility may benefit from addition of E-EPA to their diet.
  • Alanne, Leena; Bhide, Amarnath; Hoffren, Jonna; Lantto, Juulia; Huhta, Heikki; Kokki, Merja; Haapsamo, Mervi; Acharya, Ganesh; Räsänen, Juha (2020)
    Introduction We hypothesized that nifedipine and sildenafil would have no detrimental effects on placental hemodynamics and gas exchange under fetal hypoxemia. Methods In 33 chronically instrumented fetal sheep, placental volume blood flow (QPlac) and umbilical artery (UA) vascular impedance were measured by Doppler ultrasonography. Fetal carotid artery blood pressure and blood gas values were monitored. After baseline data collection, maternal and fetal hypoxemia were induced. Following hypoxemia phase data collection, 12 fetuses received sildenafil and 9 fetuses nifedipine infusion, and 12 fetuses served as controls receiving saline infusion. Data were collected 30 and 120 min after infusion was started. Then maternal oxygenation was normalized and normoxemia phase data were collected, while infusion was continued. Results Hypoxemia significantly decreased fetal pO2 and blood pressure. In the sildenafil group at 30- and 120-min hypoxemia + infusion phases, fetal blood pressure and QPlac were significantly lower and pCO2 higher than at baseline without returning to baseline level at normoxemia + infusion phase. In hypoxemia, nifedipine did not affect fetal blood pressure or placental hemodynamics. Both in the sildenafil and nifedipine groups, fetal pO2 remained significantly lower at normoxemia + infusion phase than in the control group. Umbilical artery vascular impedance did not change during the experiment. Discussion In fetal hypoxemia, sildenafil had detrimental effects on placental hemodynamics that disturbed placental gas exchange. Nifedipine did not alter placental hemodynamics in hypoxemia but disturbed placental gas exchange upon returning to normoxemia. Umbilical artery vascular impedance did not reflect alterations in placental hemodynamics.
  • Haller, Albert von (Albertus de)(Albrecht) (Lausanne, 1763)
  • Haller, Albert von (Albertus de)(Albrecht) (Bern, 1764)
  • Haller, Albert von (Albertus de)(Albrecht) (Lausanne, 1760)
  • Haller, Albert von (Albertus de)(Albrecht) (Lausanne, 1762)
  • Haller, Albert von (Albertus de)(Albrecht) (Lausanne, 1757)
  • Haller, Albert von (Albertus de)(Albrecht) (Lausanne, 1761)
  • Haller, Albert von (Albertus de)(Albrecht) (Bern, 1765)
  • Haller, Albert von (Albertus de)(Albrecht) (Bern, 1766)
  • Haller, Albert von (Albertus de)(Albrecht) (Lausanne, 1802)
  • Ahlsten, Manuel (Helsingfors universitet, 2011)
    Germline mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene were recently shown to predispose to pituitary adenomas, which are neoplasms of the anterior pituitary gland. AIP mutations were first discovered in a cluster of familial pituitary adenomas in Northern Finland and afterwards in several populations worldwide. AIP associated pituitary adenomas are predominantly growth hormone secreting, thus several patients present with acromegaly or gigantism. The aim of this study was to elucidate AIP related pituitary tumorigenesis. AIP is suggested to be involved in several cellular pathways such as the xenobiotic response. In the cytosol, AIP interacts directly with aryl hydrocarbon receptor (AHR). After interaction with xenobiotic compounds AHR translocates to the nucleus and binds aryl hydrocarbon receptor nuclear translocator (ARNT). The AHR/ARNT heterodimer regulates the expression of several xenobiotic metabolizing enzymes. The AHR pathway is linked to e.g. the hypoxia response and estrogen signaling through ARNT and possibly through ARNT2, an ARNT homolog. A previously generated heterozygous Aip (Aip+/-) mouse model was used to study the role of these pathways in AIP-mediated tumorigenesis. Immunohistochemical studies revealed that expression of either ARNT or ARNT2 protein was lost in the mouse tumors. Aip+/- mice were also crossed and pregnant mice dissected to acquire Aip knockout (Aip-/-) and Aip wildtype (Aip+/+) embryos. Mouse embryonic fibroblast cell lines were prepared from these embryos and protein extracts were used for western blot analysis. This analysis revealed that expression of ARNT and ARNT2 was uniform between Aip-/- and Aip+/+ cell lines, which suggests that aberrant ARNT/ARNT2 expression is pituitary specific. In addition, Ki-67 analysis indicated that Aip deficient tumors have higher proliferation rates as compared with Aip proficient tumors. These results suggest that mechanisms of AIP related pituitary tumorigenesis involve aberrant ARNT/ARNT2 function, possibly via the AHR, hypoxia or estrogen pathways. Furthermore, the comparatively high proliferation rates of Aip deficient tumors may correlate with a more aggressive disease. Concentration is next focused on acquiring gene expression data of early Aip-/- embryos, which will be compared with expression data of Aip+/+ embryos. Differential expression patterns in these embryos could give new insights on different pathways involving AIP. Revealing the molecular basis of AIP related pituitary tumorigenesis is important in order to develop new diagnostic and therapeutic strategies for several patients suffering with pituitary adenomas.
  • Hovinen, Mari (Helsingfors universitet, 2000)
    Viikin koetilalla tehtiin syksyn 1998 ja kevään 1999 aikana vasikoiden vierihoitotutkimus. Mukaan otettiin 18 vasikkaa, jotka jaettiin sattumanvaraisesti kolmeen ryhmään: 8 viikon vierihoito (ryhmä 1), 5 viikon vierihoito (ryhmä 2) ja kontrolliryhmä (ryhmä 3). Vasikat olivat yksittäiskarsinoissa, ja pääsivät imemään emäänsä parteen kahdesti päivässä lypsyn jälkeen. Kontrolliryhmä joi maidon tuttiämpäristä. 5 viikon iässä ryhmä 2 ei saanut enää maitoa, ja ryhmät 1 ja 3 saivat maitoa enää kerran päivässä. Kuivarehua annettiin alusta lähtien vapaasti. Vasikoiden terveyttä seurattiin päivittäin kirjaamalla ulosteen konsistenssi, yskän esiintyvyys ja vasikoiden hoidot. Verinäytteitä otettiin 2-4 vrk:n ja 2 viikon iässä, 5 viikon iässä 0-2 vrk ennen ja 1-3 vrk jälkeen vieroituksen , 6,5 viikon iässä, 8 viikon iässä 0-2 vrk ennen vieroitusta, sekä 9,5 ja 12 viikon iässä. Verinäytteistä analysoitiin punasolut, Hkr, Hb, MCV, MCH, MCHC, rauta, valkosolut, valkosolujen erittelylaskenta, fibrinogeeni, haptoglobiini, IgG, GGT, CK, ASAT, proteiini, albumiini, urea, glukoosi, vapaat rasvahapot ja kortisoli. Tutkimusvasikoilla oli paljon ripulia, mikä heikentää aineistoa. Silti tulokset vastaavat hyvin muista tutkimuksista saatuja tuloksia. Vasikoilla oli jonkin verran anemiaa 1-1,5 kuukauden iässä. Tähän saattaa vaikuttaa raudanpuute ja hiehojen suuri määrä. Ruokinnan vaikutus näkyi selkeästi veriarvoissa; kuivarehuun siirtyminen nosti veren proteiini-, urea- ja rautapitoisuutta ja laski veren glukoosipitoisuutta. Vieroituksen yhteydessä vasikoiden elimistössä tapahtui lievää kuivumista, sillä hematokriitti näytti nousevan vieroituksessa, lisäksi proteiini-, albumiini ja ureapitoisuus nousivat. Ryhmän 1 lievä stressileukogrammi vieroituksen yhteydessä saattaa indikoida vieroitustressin vaikutusta, sen sijaan kortisolitasoon vieroitustressillä ei näyttänyt olevan ainakaan pidempiaikaista vaikutusta. Ryhmien välillä oli joitain yksittäisiä eroja mittausajankohdittain. Ryhmän 1 vasikoilla oli alhaisempi proteiinitaso kuin ryhmällä 2 ja alhaisempi albumiini- ja ureataso kuin muilla ryhmillä 5 - 8 viikon iässä, jonka jälkeen erot tasoittuivat 9,5 viikon ikään mennessä. Erot johtuvat ilmeisesti ryhmän 1 alhaisemmasta kuivarehun syönnistä.
  • Haller, Albert von (Albertus de)(Albrecht) (Berlin, 1788)