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Variations of taste perception and possible association with bmi in healthy subjects: a functional and genomic approach
Full text linkIl senso del gusto è parte del sistema sensoriale ed è una fonte importante di input sensoriali: esso influenza
l'appetibilità e il grado di accettazione di cibi o bevande. Esistono sei diversi gusti ad oggi noti, amaro, dolce,
acido, salato, umami e gusto del grasso.
Alcuni studi hanno stabilito una relazione tra variazione genetica, percezione del gusto e stato di salute:
variazioni genetiche nei geni dei recettori del gusto inducono variazioni nella percezione del gusto. Tuttavia,
la selezione del cibo dipende anche da altri fattori come lo stato nutrizionale, la fisiologia, l'ambiente e i
fattori socioculturali.
Le scelte del cibo e le abitudini alimentari possono influenzare lo stato di salute e il rischio di sviluppare
malattie complesse.
Il metodo più comunemente usato per studiare le patologie complesse è lo studio di associazione, che mira
ad identificare, in una popolazione, una correlazione tra gli alleli di uno o più marcatori genetici, soprattutto i
singoli nucleotidi polimorfici (SNP), e il fenotipo.
L'obiettivo generale di questa tesi è quello di indagare come la percezione gustativa influenza l’ indice di
massa corporea (BMI) e predispone a malattie complesse come l'obesità.
Questa ricerca include 5100 partecipanti provenienti da tre diversi progetti all'interno del consorzio
“Network Italiano Isolati Genetici” (INGI).
I DNA genomici dei soggetti sono stati estratti da campioni di sangue e poi genotipizzati utilizzando
“Illumina 370K high-throughput SNP array”, per un totale di circa 370.000 SNP per campione.
Attraverso la consultazione del database bibliografico PubMed abbiamo selezionato tutti i geni recettori del
gusto e i geni coinvolti nella cascata di trasduzione del segnale del gusto.
Abbiamo eseguito una "analisi di associazione per geni candidati" assumendo il log10 del BMI come
variabile dipendente e gli SNP di tutti i geni selezionati come regressori. Abbiamo utilizzato un modello
genetico additivo e abbiamo assunto sesso ed età come covariate.
Ogni popolazione è stata prima analizzata separatamente e poi risultati sono stati combinati mediante metaanalisi.
Dopo l’analisi del fenotipo e del genotipo, 2827 soggetti sono stati analizzati complessivamente. La metaanalisi
ha identificato alcuni polimorfismi associati con il BMI: 2 SNP appartengono al gene SCNN1B gene,
un recettore del gusto salato, invece otto SNP appartengono al gene GNAT3, un gene che codifica una
proteina-G gusto-selettiva implicata nella trasduzione del gusto dolce, amaro e umami, e 4 SNPs
appartengono al gene PDE4B, una fosfodiesterasi AMPc-specifica per la trasduzione del segnale in generale.
I risultati dei nostri studi suggeriscono che il meccanismo con cui le variazioni dei recettori del gusto
possono influenzare il BMI, e quindi il rischio di sviluppare sovrappeso e obesità, è molto complesso e
probabilmente strettamente correlato all’espressione e alla funzione dei recettori del gusto.
I nostri risultati confermano che questi geni sono altamente polimorfici e che questi polimorfismi sono legati o alla proteina del recettore o alla proteina coinvolta nella cascata del segnale.The sense of the taste is part of the sensory system and is an important source of sensory input: it influences
the palatability and the degree of acceptance of foods or drinks. There are six different tastes until now
known, bitter, sweet, sour, salt, umami and fat taste.
Some studies established a relationship between genetic variation, taste perception and health status: genetic
variations in taste receptor genes induce variations in taste perception. However, food selection depends also
on other factors like nutritional status, physiology, environment and sociocultural factors.
Food choices and dietary habits may influence the health status and the risk of complex diseases.
The method most commonly used for studying the complex disease is the association study, that aims to
identify, in a population, a correlation between the alleles of one or more genetic markers, mostly the Single
Nucleotide Polymorphisms (SNPs), and the phenotype.
The general aim of this thesis is to investigate how taste perception affects body mass index (BMI) and
predisposes to complex diseases such as obesity.
This research includes 5100 participants from three different projects within “Italian Network on Genetic
Isolate” (INGI) consortium.
Genomic DNAs of subjects were extracted from blood samples and then were genotyped using Illumina
370k high-throughput SNP arrays, for a total of about 370.000 SNPs per samples.
We selected all the taste receptors genes and the genes involved in the cascade of taste signal transduction
through consultation of bibliographic database PubMed.
We carry out a “candidate gene association analysis” assuming the log10 of BMI as the dependent variable
and the SNPs of all selected genes as the regressors. We used an additive genetic model and gender and age
as covariates.
Each population was firstly separately analyzed and results were combined using meta-analysis.
After phenotype and genotype analysis, 2827 subjects were analyzed overall. Meta-analyses identified some
polymorphisms associated with the BMI: 2 SNPs belong to SCNN1B gene, which is a salty taste receptor,
instead 8 SNPs belong to GNAT3 gene, a gene encoding a taste-selective G protein of transduction of sweet,
bitter and umami taste, and 4 SNPs belong to PDE4B gene, which is a phosphodiesterase AMPc-specific for
signal transduction in general.
The outcomes of our studies suggest that the mechanism by which variations in taste receptors may influence
the BMI, and therefore the risk of developing overweight and obesity, is very complex and probably closely
related to expression and function of the taste receptors.
Our results confirm that these genes are highly polymorphic and these polymorphisms are related to either
protein receptor or protein involved in signaling cascade
Relationship between blood lactate and cortical excitability between taekwondo athletes and non-athletes after hand-grip exercise
No full textAbstract: Objectives: In taekwondo competitions, fatigue has a large influence on performance. Recent studies have reported that the excitability in the primary hand motor cortex, investigated with transcranial magnetic stimulation (TMS), is enhanced at the end of a maximal exercise and that this improvement correlates with blood lactate. The aim of the present study was to investigate the relationship between blood lactate and cortical excitability in taekwondo athletes and non-athletes. Methods: The excitability of the primary motor cortex was measured before and after fatiguing hand-grip exercise by TMS. Capillary blood lactate was measured at rest (pre-test), at the end (0 min), and at 3 and 10 min after the exercise by using a “Lactate Pro” portable lactate analyzer. Results: Significant differences in cortical excitability between the two groups were found after the exercise (p < 0.05). Furthermore, we found a significant relationship between cortical excitability and blood lactate (p < 0.01). Conclusion: The present findings showed changes in the excitability in the athletes group and also in the non-athletes group. However, blood lactate seems to have the greater effect in trained subjects compared to untrained subjects. In fact, it appears that, during extremely intensive exercise in taekwondo athletes, lactate may delay the onset of fatigue not only by maintaining the excitability of muscle, but also by increasing the excitability of the primary motor cortex more than in non-athletes
Heart rate variability is reduced in underweight and overweight healthy adult women
No full textHeart rate variability (HRV) is altered in obese subjects, but whether this is true also in underweight (UW) subjects is still under debate. We investigated the HRV profile in a sample of healthy adult women and its association with adiposity. Five-minute resting state electrocardiographic activity was recorded in 69 subjects grouped according to their body mass index, [23 normal weight (NW), 23 overweight/obese (OW) and 23 UW). Body fat mass (FM) was measured by bio-impedance. Frequency- and time-domain analyses were performed. Compared to NW, UW and OW subjects showed a significant decrease in HRV indices, as revealed by spectral analysis. No differences were observed between UW and OW subjects. A second-order polynomial regression unveiled an inverted U-shaped relationship between FM extent and HRV indices. A decrease of HRV indices was associated with changes in FM extent, proving that in UW and OW subjects, the adaptive flexibility of autonomic cardiac function was reduced. These findings provide important clues to guide future studies addressed to determine how changes in adiposity and autonomic cardiac function may contribute to health risk
Functional Assessment of Corticospinal System Excitability in Karate Athletes.
No full textObjectivesTo investigate the involvement of the primary motor cortex (M1) in the coordination performance of karate athletes through transcranial magnetic stimulation (TMS).MethodsThirteen right-handed male karate athletes (25.0±5.0 years) and 13 matched non-athlete controls (26.7±6.2 years) were enrolled. A single-pulse TMS was applied using a figure-eight coil stimulator. Resting motor threshold (rMT) was determined. Surface electromyography was recorded from the first dorsal interosseous muscle. Motor evoked potential (MEP) latencies and amplitudes at rMT, 110%, and 120% of rMT were considered. Functional assessment of the coordination performance was assessed by in-phase (IP) and anti-phase (AP) homolateral hand and foot coordination tasks performed at 80, 120, and 180 bpm.ResultsCompared to controls, athletes showed lower rMT (pConclusionWith respect to controls, karate athletes present a higher corticospinal excitability indicating the presence of an activity-dependent alteration in the balance and interactions between inhibitory and facilitatory circuits determining the final output from the M1. Furthermore, the high correlation between corticospinal excitability and coordination performance could support sport-specific neurophysiological arrangements
Correction: Functional Assessment of Corticospinal System Excitability in Karate Athletes.
No full text[This corrects the article DOI: 10.1371/journal.pone.0155998.]
Heart rate variability is reduced in underweight and overweight healthy adult women
No full textHeart rate variability (HRV) is altered in obese subjects, but whether this is true also in underweight (UW) subjects is still under debate. We investigated the HRV profile in a sample of healthy adult women and its association with adiposity. Five-minute resting state electrocardiographic activity was recorded in 69 subjects grouped according to their body mass index, [23 normal weight (NW), 23 overweight/obese (OW) and 23 UW). Body fat mass (FM) was measured by bio-impedance. Frequency- and time-domain analyses were performed. Compared to NW, UW and OW subjects showed a significant decrease in HRV indices, as revealed by spectral analysis. No differences were observed between UW and OW subjects. A second-order polynomial regression unveiled an inverted U-shaped relationship between FM extent and HRV indices. A decrease of HRV indices was associated with changes in FM extent, proving that in UW and OW subjects, the adaptive flexibility of autonomic cardiac function was reduced. These findings provide important clues to guide future studies addressed to determine how changes in adiposity and autonomic cardiac function may contribute to health risk
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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