Taste Perception And Food Choices

OBJECTIVES: The extent to which variation in taste perception influences food preferences is, to date, controversial. Bitterness in food triggers an innate aversion that is responsible for dietary restriction in children. We investigated the association among genetic variations in bitter receptor TAS2R38 and food choices in healthy children in the Mediterranean area, to develop appropriate tools to evaluate the relation among genetic predisposition, dietary habits, and feeding disorders. The aims of the study were to get a first baseline picture of taste sensitivity in healthy adults and their children and to explore taste sensitivity in a preliminary sample of obese children and in samples affected by functional gastrointestinal diseases. METHODS: Individuals (98 children, 87 parents, 120 adults) were recruited from the general population in southern Italy. Bitterness sensitivity was assessed by means of a suprathreshold method with 6-propyl-2-thiouracil. Genomic DNA from saliva was used to genotype individuals for 3 polymorphisms of TAS2R38 receptor, A49P, A262 V, and V296I. Food intake was assessed by a food frequency questionnaire. RESULTS: Children's taste sensation differed from that of adults: we observed a higher frequency of supertasters among children even in the mother-child dyads with the same diplotypes. Among adults, supertaster status was related with proline-alanine-valine (taster allele) homozygous haplotype, whereas supertaster children were mainly heterozygous. Regarding the food choices, we found that a higher percentage of taster children avoided bitter vegetables or greens altogether compared with taster adults. Taster status was also associated with body mass index in boys. CONCLUSIONS: Greater sensitivity to 6-propyl-2-thiouracil predicts lower preferences for vegetables in children, showing an appreciable effect of the genetic predisposition on food choices. None of the obese boys was a supertaster

COVID-19 and genetic variants of protein involved in the SARS-CoV-2 entry into the host cells

The recent global COVID-19 public health emergency is caused by SARS-CoV-2 infections and can manifest extremely variable clinical symptoms. Host human genetic variability could influence susceptibility and response to infection. It is known that ACE2 acts as a receptor for this pathogen, but the viral entry into the target cell also depends on other proteins. The aim of this study was to investigate the variability of genes coding for these proteins involved in the SARS-CoV-2 entry into the cells. We analyzed 131 COVID-19 patients by exome sequencing and examined the genetic variants of TMPRSS2, PCSK3, DPP4, and BSG genes. In total we identified seventeen variants. In PCSK3 gene, we observed a missense variant (c.893G>A) statistically more frequent compared to the EUR GnomAD reference population and a missense mutation (c.1906A>G) not found in the GnomAD database. In TMPRSS2 gene, we observed a significant difference in the frequency of c.331G>A, c.23G>T, and c.589G>A variant alleles in COVID-19 patients, compared to the corresponding allelic frequency in GnomAD. Genetic variants in these genes could influence the entry of the SARS-CoV-2. These data also support the hypothesis that host genetic variability may contribute to the variability in infection susceptibility and severity

On a class of forward-backward parabolic equations: Properties of solutions

We study the equation ut = [φ(u)]xx + ϵ[ψ(u)]txx with suitable boundary conditions and a nonnegative Radon measure as initial datum. Here φ(0) = φ(∞) = 0, φ is increasing in (0, α) and decreasing in (α,∞), and the regularizing term ψ is increasing but bounded. It is natural to study measure-valued solutions since singularities may appear spontaneously in finite time. Positive measure-valued solutions are known to exist and to not be unique. In this paper we study qualitative properties shared by all solutions of the problem. We prove, among other things, that the singular part of a solution is nondecreasing with respect to time, so its support is nonshrinking, and, due to the possible appearance of singularities, may even expand. This phenomenon sharply distinguishes the case of bounded ψ from those of power-type ψ, where the singular part remains constant in time, and logarithmic ψ, where the singular part may grow but its support does not expand. It also distinguishes the present case from the case of φ increasing in (0, α), decreasing in (α, β), increasing in (β,∞) for some 0 < α < β < ∞, and bounded (with ψ as in this paper), where the singular part of a solution is nonincreasing in time and singularities may disappear

Pseudo-parabolic regularization of forward- backward parabolic equations: Power-type nonlinearities

We study a quasilinear parabolic equation of forward-backward type, under assumptions on the nonlinearity which hold for a wide class of mathematical models, using a pseudo-parabolic regularization of power type.We prove existence and uniqueness of positive solutions of the regularized problem in a space of Radon measures. It is shown that these solutions satisfy suitable entropy inequalities. We also study their qualitative properties, in particular proving that the singular part of the solution with respect to the Lebesgue measure is constant in time

Pseudoparabolic regularization of forward-backward parabolic equations: a logarithmic nonlinearity

We study the initial-boundary value problem u_t = Δφ(u) + εΔ[ψ(u)]_t in Q := Ω×(0, T], φ(u) + ε[ψ(u)]_t = 0 in ∂Ω×(0, T], u = u_0 ≥0 in Ω×{0}, with measure-valued initial data, assuming that the regularizing term ψ has logarithmic growth (the case of power-type ψ was dealt with in an earlier work). We prove that this case is intermediate between the case of power-type ψ and that of bounded ψ, to be addressed in a forthcoming paper. Specifically, the support of the singular part of the solution with respect to the Lebesgue measure remains constant in time (as in the case of power-type ψ), although the singular part itself need not be constant (as in the case of bounded ψ, where the support of the singular part can also increase). However, it turns out that the concentrated part of the solution with respect to the Newtonian capacity remains constant

Nonuniqueness of solutions for a class of forward-backward parabolic equations

We study the initial–boundary value problem with measure-valued initial data. Here Ω is a bounded open interval, φ(0)=φ(∞)=0, φ is increasing in (0,α) and decreasing in (α,∞), and the regularising term ψ is increasing but bounded. It is natural to study measure-valued solutions since singularities may appear spontaneously in finite time. Nonnegative Radon measure-valued solutions are known to exist and their construction is based on an approximation procedure. Until now nothing was known about their uniqueness. In this note we construct some nontrivial examples of solutions which do not satisfy all properties of the constructed solutions, whence uniqueness fails. In addition, we classify the steady state solutions

Discontinuous viscosity solutions of first-order Hamilton-Jacobi equations

We study the Cauchy problem for the simplest first-order Hamilton-Jacobi equation in one space dimension, with a bounded and Lipschitz continuous Hamiltonian which only depends on the spatial derivative. Uniqueness of discontinuous viscosity solutions is proven, if the initial data function has a finite number of jump discontinuities. Main ingredients of the proof are the barrier effect of spatial discontinuities of a solution (which is linked to the boundedness of the Hamiltonian), and a comparison theorem for semicontinuous viscosity subsolution and supersolution. These are defined in the spirit of the paper [H. Ishii, Perron's method for Hamilton-Jacobi equations, Duke Math. J. 55 (1987) 368-384], yet using essential limits to introduce semicontinuous envelopes. The definition is shown to be compatible with Perron's method for existence and is crucial in the uniqueness proof. We also describe some properties of the time evolution of spatial jump discontinuities of the solution, and obtain several results about singular Neumann problems which arise in connection with the above referred barrier effect