Browsing by Subject "herkkyys"

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  • Auranen, Johanna (Helsingfors universitet, 2007)
    Campylobacters are the most common bacterial cause of diarrhoea in humans. In Finland there were more than 3500 cases reported in 2006 (National Public Health Institute, www.ktl.fi). Cattle carry prevalently campylobacters, generally Campylobacter jejuni, C. hyointestinalis subsp. hyointestinalis and C. coli. Campylobacters are zoonotic. Animals and animal origin food products can be vectors of human infections. Unpasteurized milk has proved to be an important risk factor in epidemiologic studies. Also in sporadic epidemics unpasteurized milk has been proved to be an infectious vector. Arcobacters belong to the same family as campylobacters. Arcobacters are very similar to campylobacters in their character, except that arcobacters are aerotolerant while campylobacters can grow only in a microaerophilic atmosphere. Arcobacter's pathogenity is unclear and in epidemiologic understanding their importance as pathogens is not as great as that of campylobacters. In this research the occurrence of campylobacters and arcobacters in raw milk, cattle faeces and flies was studied. Samples were collected at eight dairy farms in southern Finland and at one dairy farm in western Finland in June and July 2007. Campylobacters and arcobacters were examined by using an enrichment procedure and selective culturing. Isolated strains were classified with biochemical tests, PCR-technique and comparing their growth abilities. Campylobacters and arcobacters were quantified in milk using Most Probable Number -method. In addition, the survival of C. jejuni ATCC 33560 and C. hyointestinalis CH1/06 strains were examined in sterile milk at three temperatures (4 °C, 25 °C and 37 °C) for three days. C. hyointestinalis was isolated from raw milk at one of the dairy farms in June. The bacter quantity was MPN 11/100 ml. A. butzleri was isolated from raw milk at the same farm in June MPN 285/100 ml and in July MPN 52/100 ml. C. hyointestinalis was isolated from faeces at another farm in June while in July A. butzleri was isolated from raw milk MPN 52/100 ml at the same farm. At a third farm A. butzleri was isolated from raw milk MPN 71/100 ml and from faeces. Campylobacters can pass on to raw milk during milking as a consequence of faeces contamination. Arcobacters' access to a milk tank was not examined but as environmental bacters they might enter the tank along with milk or during tank wash, and form a bio film on the wall of the tank. The quantity of C. jejuni and C. hyointestinalis strains remained remarkable at every temperature examined. On the other hand, in sterile milk there were no competitive microbial organisms, nor their metabolic products, both of which could reduce the studied strains' survival in raw milk.
  • Roukka, Matti (Helsingin yliopisto, 2020)
    The chemesthesis perception needs to be researched so that we can better understand how it works in different individuals and affects them. Chemesthesis, smell and taste chemical senses have an important role in individual food choices and health. The primary goal was to study the individual differences in perception of chemesthesis. The data for this study was collected at the University of Turku Functional Food Forum sensory laboratory (ISO 8589). The data includes sensory study results about chemesthetic properties such as astringency, burning and cooling, which are the properties analysed in this study. Study subjects (N=196) evaluated the intensity of these three properties. Every property had five sensory samples presented in different concentrations. Based on the results, the intensity rate was classified into three groups (non-sensitive, semi-sensitive, most sensitive) with Hierarchical clustering. The differences of the formed groups were analysed with the one-way multivariate analysis of variance which gave statistically significant results (F = 10.0; p ≤ 0.001). Mean values of the cluster groups from three different chemesthetic properties were combined into chemesthesis scores. Age didn’t affect the chemesthesis score (F = 0.5; p > 0.05). Female subjects’ chemesthesis scores differ from the male subjects’ scores (F = 5.1; p ≤ 0.01). The correlation between chemesthesis and taste was tested from Puputti et al. (2018) created taste score with data from the same subjects, and chemesthesis score. Chemesthesis score and taste score had a positive correlation (r = +0.561; p ≤ 0.01). The results show that individuals differ in the perception of chemesthesis. The chemesthesis score can classify individuals to different sensitivity groups and chemesthesis appears to correlate with taste. There are many chemesthetic sensations whose properties and mechanisms are unknown. The objectives of the research were achieved. The research is a part of Professor Mari Sandell’s the Academy of Finland funded Food Taste research program and was done during the COVID-19 pandemic.
  • Karonen, Taru (Helsingin yliopisto, 2019)
    Kolistiini on polymyksiineihin kuuluva antibiootti, joka kuuluu kriittisen tärkeisiin reserviantibiootteihin. Sen käyttö tulisi rajata erityisesti ihmisille ainoastaan todennettuun tarkoitukseen, esimerkiksi muille antibiooteille vastaamattomien, moniresistenttien bakteeri-infektioiden hoitoon. Syksyllä 2017 Evira löysi ensimmäisen kerran Suomeen Venäjältä tuoduista löytökoirista kolistiinille resistenttejä, ESBL-positiivisia Escherihia coli -bakteereja. Näistä bakteereista kolistiiniresistenssi todettiin referenssimenetelmällä eli liemilaimennosmenetelmällä ja kolistiinireisstenssiyden tuova mcr-1-geeni PCR-menetelmällä. Helsingin yliopiston eläinlääketieteellisen tiedekunnan kliinisen mikrobiologian laboratoriossa on seulottu alati kasvavasta potilasnäytemäärästä kolistiiniresistenssiä polymyksiini B -kiekkoherkyysmenetelmällä, koska sen on oletettu tuovan esille kolistiinille resistentit kannat polymyksiineille ominaisen ristiresistenssin vuoksi. Menetelmässä on myös jouduttu turvautumaan Pseudomonas aeruginosa -bakteerin herkkyysraja-arvoihin, koska enterobakteereille ei ole määritelty erikseen herkkyysraja-arvoja. Ei kuitenkaan tiedetä, kuinka luotettavasti ja herkästi tämä herkkyysmenetelmä soveltuu kolistiiniherkkyyden seulontaan. Työ koostuu kirjallisuuskatsauksesta ja kokeellisesta osasta. Kokeellisen osan tarkoituksena oli vertailla kolmea eri herkkyysmenetelmää kolistiiniresistenssin testaamiseksi ja pohtia P. aeruginosan raja-arvojen soveltumista enterobakteereille. Samalla tutkittiin, oliko potilasaineistossa mahdollisesti jäänyt havaitsematta aiemmassa polymyksiini B -kiekkotestissä kolistiinille resistenttejä, mcr-1- positiivisia kantoja. Työn hypoteesina oli, ettei polymyksiini B -kiekkotesti ole tarpeeksi herkkä ja spesifinen menetelmä kolistiiniherkkyyden testaamiseen. Tutkittavina potilaskantoina oli 31 kpl ESBL-positiivisiksi osoittautunutta E. coli -kantaa. Tutkittavat kannat oli eristetty Suomeen Venäjältä (26 kpl), Romaniasta (4 kpl) tai Latviasta (1 kpl) tuoduista, eri-ikäisistä koirista vuosina 2017-2018. Negatiivisina kontrollikantoina käytettiin kolistiinille herkkää E. coli ATCC 25922 -kantaa sekä P. aeruginosa ATCC 27852 -kantaa. Positiivisina kontrolleina (mcr-1 geeni) käytettiin E. coli NCTC 13846 -kantaa sekä kolmea Evirasta saatua mcr-1 –positiivista kantaa. Testattavina menetelminä olivat kiekkoherkkyysmenetelmä (polymyksiini B- ja kolistiinikiekot 10 ,25 ja 50 μg), E-testi (kolistiini), sekä referenssimenetelmänä liemilaimennosmenetelmä (kolistiini). Herkkyysmenetelmissä kolistiinille resistenteiksi osoittautuneet potilaskannat tutkittiin Evirassa mcr-1-geenin osalta PCR-menetelmällä. Työssä osoittautui, ettei polymyksiini B -kiekkotesti sovellu kolistiiniherkkyyden seulontaan eivätkä P. aeruginosan raja-arvot sovellu enterobakteereille. Kaikki kannat, mukaan lukien resistentit kannat, olivat tämän testin perustella herkkiä kolistiinille. Kolistiinikiekkoherkkyystesti (10 μg kiekko), E-testi ja liemilaimennosmenetelmä erottivat herkät ja resistentit kannat toisistaan. PCR-tutkimuksessa 2/31 potilaskantaa kantoivat mcr-1-geeniä, eli geenin esiintyvyys oli 6,5 %. Tämän työn perusteella polymyksiini B-kiekkotesti tulisi korvata toisella herkkyysmenetelmällä, esimerkiksi 10 μg kolistiinikiekkotestillä tai E-testillä. Liemilaimennosmenetelmän vaativuuden ja kalleuden vuoksi se soveltuisi tulosten varmentamiseen PCR-menetelmän ohella. Lisätutkimuksia kuitenkin vaaditaan mm. herkkyysraja-arvojen määrittämiseen ja menetelmien optimoimiseen. Koska työssä löydettiin jo toisen kerran kolistiinille reisistenttejä bakteereja tuontikoirista, vahvistaa työ tarvetta seuloa erityisesti tuontikoiria kolistiiniresistenssin suhteen.
  • Melero, Yolanda; Evans, Luke C.; Kuussaari, Mikko; Schmucki, Reto; Stefanescu, Constantí; Roy, David B.; Oliver, Tom H. (Springer Science and Business Media LLC, 2022)
    Communications Biology
    Climatic anomalies are increasing in intensity and frequency due to rapid rates of global change, leading to increased extinction risk for many species. The impacts of anomalies are likely to vary between species due to different degrees of sensitivity and extents of local adaptation. Here, we used long-term butterfly monitoring data of 143 species across six European bioclimatic regions to show how species’ population dynamics have responded to local or globally-calculated climatic anomalies, and how species attributes mediate these responses. Contrary to expectations, degree of apparent local adaptation, estimated from the relative population sensitivity to local versus global anomalies, showed no associations with species mobility or reproductive rate but did contain a strong phylogenetic signal. The existence of phylogenetically-patterned local adaptation to climate has important implications for forecasting species responses to current and future climatic conditions and for developing appropriate conservation practices.