A matter of taste : genetic and environmental influences on responses to sweetness

Diet is a major player in the maintenance of health and onset of many diseases of public health importance. The food choice is known to be largely influenced by sensory preferences. However, in many cases it is unclear whether these preferences and dietary behaviors are innate or acquired. The aim of this thesis work was to study the extent to which the individual differences in dietary responses, especially in liking for sweet taste, are influenced by genetic factors. Several traits measuring the responses to sweetness and other dietary variables were applied in four studies: in British (TwinsUK) and Finnish (FinnTwin12 and FinnTwin16) twin studies and in a Finnish migraine family study. All the subjects were adults and they participated in chemosensory measurements (taste and smell tests) and filled in food behavior questionnaires. Further, it was studied, whether the correlations among the variables are mediated by genetic or environmental factors and where in the genome the genes influencing the heritable traits are located. A study of young adult Finnish twins (FinnTwin16, n=4388) revealed that around 40% of the food use is attributable to genetic factors and that the common, childhood environment does not affect the food use even shortly after moving from the parents home. Both the family study (n=146) and the twin studies (British twins, n=663) showed that around half of the variation in the liking for sweetness is inherited. The same result was obtained both by the chemosensory measurements (heritability 41-49%) and the questionnaire variables (heritability 31-54%). By contrast, the intensity perception of sweetness or the responses to saltiness were not influenced by genetic factors. Further, a locus influencing the use-frequency of sweet foods was identified on chromosome 16p. A closer examination of the relationships among the variables based on 663 British twins revealed that several genetic and environmental correlations exist among the different measures of liking for sweetness. However, these correlations were not very strong (range 0.06-0.55) implying that the instruments used measure slightly different aspects of the phenomenon. In addition, the assessment of the associations among responses to fatty foods, dieting behaviors, and body mass index in twin populations (TwinsUK n=1027 and FinnTwin12 n=299) showed that the dieting behaviors (cognitive restraint, uncontrolled eating, and emotional eating) mediate the relationship between obesity and diet. In conclusion, the work increased the understanding of the background variables of human eating behavior. Genetic effects were shown to underlie the variation of many dietary traits, such as liking for sweet taste, use of sweet foods, and dieting behaviors. However, the responses to salty taste were shown to be mainly determined by environmental factors and thus should more easily be modifiable by dietary education, exposure, and learning than sweet taste preferences. Although additional studies are needed to characterize the genetic element located on chromosome 16 that influences the use-frequency of sweet foods, the results underline the importance of inherited factors on human eating behavior.Ruokavalio on tärkeä terveyteen ja monien kansanterveyden kannalta tärkeiden sairauksien puhkeamiseen vaikuttava tekijä. Kehittyneissä maissa ruokavalinnat määräytyvät pitkälti makumieltymysten perusteella. Kuitenkin monissa tapauksissa on epäselvää, ovatko makumieltymykset ja syömiskäyttäytymismallit synnynnäisiä vai opittuja. Tämän väitöskirjatutkimuksen tavoitteena oli selvittää, kuinka suurelta osin makean mieltymykset ja muut ruokaorientaatiota kuvaavat tekijät periytyvät. Aineisto kerättiin neljässä tutkimuksessa: suomalaisessa migreeniperhetutkimuksessa sekä brittiläisessä ja suomalaisissa kaksostutkimuksissa. Yhteensä yli 5000 vapaaehtoista koehenkilöä osallistui makutesteihin ja/tai täytti syömiskäyttäytymiskyselyitä. Jatkoanalyyseissa tutkittiin, johtuivatko mittareiden väliset korrelaatiot geneettisistä vai ympäristötekijöistä sekä pyrittiin paikantamaan periytyviin ominaisuuksiin vaikuttavia geneettisiä tekijöitä. Suomalaisia nuoria aikuisia käsitellyt tutkimus osoitti, että n. 40 % eroista ruokien käytössä selittyi perinnöllisillä tekijöillä ja että lapsuuden perheympäristö ei vaikuta ruokien käyttöön tilanteessa, jossa suurin osa koehenkilöistä oli vastikään muuttanut pois vanhempiensa luota. Sekä perhetutkimus että kaksostutkimukset osoittivat, että noin puolet eroista makean mieltymyksissä johtui geneettisistä tekijöistä. Sama tulos saatiin sekä aistitestauksilla että kyselylomakkeilla. Sen sijaan suolaisen maun aistimukset ja mieltymykset eivät olleet periytyviä. Lisäksi saatiin selville, että kromosomissa 16 sijaitsee geneettinen tekijä, joka vaikuttaa makeiden ruokien käytön useuteen. Muuttujien yhteyksien tarkempi tarkastelu osoitti, että samat geneettiset ja ympäristötekijät vaikuttavat eri makean mittareilla saatuihin tuloksiin, mutta eri makean mieltymyksen testit mittaavat ilmiötä hieman eri näkökulmasta. Kun edelleen tarkasteltiin rasvaisten ruokien miellyttävyyden ja käytön, ruokakäyttäytymisen (syömisen rajoittaminen, kontrolloimaton syöminen, tunnesyöminen) ja painoindeksin välisiä yhteyksiä kaksospopulaatioissa havaittiin, että yhteys ruokavalion ja lihavuuden välillä kulkee ruokakäyttäytymismallien kautta. Yhteenvetona voidaan todeta, että työ lisäsi tietämystä ihmisten syömiskäyttäytymisen taustasta. Perimällä osoitettiin olevan suuri vaikutus moniin ravitsemuksellisiin tekijöihin, kuten makean mieltymyksin, makeiden ruokien käyttöön ja ruokakäyttäytymiseen. Toisaalta mieltymyksen suolaiseen makuun osoitettiin olevan pääosin ympäristön määräämää ja suolamieltymysten tulisikin siis olla muokattavissa ravitsemuskoulutuksen, altistuksen ja oppimisen avulla helpommin kuin makean mieltymysten. Vaikkakin lisätutkimuksia tarvitaan, jotta kromosomissa 16 sijaitseva makeiden elintarvikkeiden käyttöön vaikuttava geeni ja sen yhteydet muihin ominaisuuksiin saadaan selville, tutkimuksen tulokset viittaavat siihen, että periytyvillä tekijöillä on merkitystä ihmisten ruokakäyttäytymiseen

Affective responses to sweet products and sweet solution in British and Finnish adults

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Immunohistochemistry in Ovarian Malignancies: A Comparative Study in Two Different Time Eras

Background: To assess role of immunohistochemistry in identifying primary and secondary ovarian malignancies. Methods: In this descriptive cross sectional study 65 cases of ovarian malignancies diagnosed during the year 2001, with a limited immunohistochemistry support were included. An equal number of cases (65 cases) diagnosed during the year 2012, with an extended immunochemistry support, were used for the comparison. Immunostains used in these cases were CK, CK7, CK20, Cdx2, PLAP, WT1, inhibin, Calretenin, Melan A, CD99, GCDFP15, Mammoglobin LCA, CEA, AFP, CD30 and CD10. Results: The frequency of metastatic carcinoma has changed tremendously being 3% in 2001 and 35.4% in 2012. The frequencies of other malignancies in 2001 in descending order of frequency were surface epithelial tumour (74.2%), germ cell tumours (16.2%), sex cord stromal tumours (1.5%) and others (3%). In 2012, apart from metastatic carcinoma, the frequency in descending order of frequency was surface epithelial tumours (35.4%), germ cell tumours (18.5%), sex cord stromal tumours (16.2%), and others (4.6%). There was not much difference in median ages (42.74 +15.4 and 39.54 + 15.8) Conclusion: IHC has helped in identifying primary and secondary ovarian malignancies

Chlamydia trachomatis samples testing falsely negative in the Aptima Combo 2 test in Finland, 2019

Since February 2019, over 160 Chlamydia trachomatis (CT) cases testing negative or equivocal by Aptima Combo 2 (AC2) but positive by Aptima CT test run with Panther instruments occurred in Finland. The AC2 test targets chlamydial 23S rRNA while the CT test targets 16S rRNA. Sequencing of 10 strains revealed a nucleotide substitution in 23S rRNA. The significance of this for the failure of the AC2 test to detect the variant is not yet known.Peer reviewe

Chlamydia trachomatis samples testing falsely negative in the Aptima Combo 2 test in Finland, 2019

Since February 2019, over 160 Chlamydia trachomatis (CT) cases testing negative or equivocal by Aptima Combo 2 (AC2) but positive by Aptima CT test run with Panther instruments occurred in Finland. The AC2 test targets chlamydial 23S rRNA while the CT test targets 16S rRNA. Sequencing of 10 strains revealed a nucleotide substitution in 23S rRNA. The significance of this for the failure of the AC2 test to detect the variant is not yet known

Multiple Independent Loci at Chromosome 15q25.1 Affect Smoking Quantity: a Meta-Analysis and Comparison with Lung Cancer and COPD

Recently, genetic association findings for nicotine dependence, smoking behavior, and smoking-related diseases converged to implicate the chromosome 15q25.1 region, which includes the CHRNA5-CHRNA3-CHRNB4 cholinergic nicotinic receptor subunit genes. In particular, association with the nonsynonymous CHRNA5 SNP rs16969968 and correlates has been replicated in several independent studies. Extensive genotyping of this region has suggested additional statistically distinct signals for nicotine dependence, tagged by rs578776 and rs588765. One goal of the Consortium for the Genetic Analysis of Smoking Phenotypes (CGASP) is to elucidate the associations among these markers and dichotomous smoking quantity (heavy versus light smoking), lung cancer, and chronic obstructive pulmonary disease (COPD). We performed a meta-analysis across 34 datasets of European-ancestry subjects, including 38,617 smokers who were assessed for cigarettes-per-day, 7,700 lung cancer cases and 5,914 lung-cancer-free controls (all smokers), and 2,614 COPD cases and 3,568 COPD-free controls (all smokers). We demonstrate statistically independent associations of rs16969968 and rs588765 with smoking (mutually adjusted p-values<10$^{−35}$ and <10$^{−8}$ respectively). Because the risk alleles at these loci are negatively correlated, their association with smoking is stronger in the joint model than when each SNP is analyzed alone. Rs578776 also demonstrates association with smoking after adjustment for rs16969968 (p<10$^{−6}$). In models adjusting for cigarettes-per-day, we confirm the association between rs16969968 and lung cancer (p<10$^{−20}$) and observe a nominally significant association with COPD (p = 0.01); the other loci are not significantly associated with either lung cancer or COPD after adjusting for rs16969968. This study provides strong evidence that multiple statistically distinct loci in this region affect smoking behavior. This study is also the first report of association between rs588765 (and correlates) and smoking that achieves genome-wide significance; these SNPs have previously been associated with mRNA levels of CHRNA5 in brain and lung tissue

Increased Genetic Vulnerability to Smoking at CHRNA5 in Early-Onset Smokers

Recent studies have shown an association between cigarettes per day (CPD) and a nonsynonymous single-nucleotide polymorphism in CHRNA5, rs16969968

Multiple Independent Loci at Chromosome 15q25.1 Affect Smoking Quantity: a Meta-Analysis and Comparison with Lung Cancer and COPD

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