Prevalence of Listeria monocytogenes in fresh and fermented Italian sausages and ribotyping of contaminating strains

Listeria monocytogenes has been detected in fresh as well as dry and semidry fermented sausages, rendering preparation and consumption of these products as a potential risk to human health. The aims of this study were (1) to evaluate the L. monocytogenes prevalence in 288 fresh and 237 fermented sausages produced in northern Italy; (2) to quantify the average pathogen Most Probable Number (MPN) per g of sausage; (3) to evaluate the sausage strain genetic diversity by automated PvuII ribotyping; and (4) to predict the pathogenicity lineage of these isolates determining their DuPont Identification Library Codes (DUP-IDs) by EcoRI ribotyping. The overall prevalence of L. monocytogenes in the sampled sausages was 28.2%. The percentage of L. monocytogenes positive fresh sausages was significantly higher than that of fermented sausages (i.e. 38.9 vs 15.2%), which had a pathogen load always lower than 10 MPN/g. In contrast, 16.1% of fresh sausages were contaminated by 10 to 100 MPN/g and 20.5% had more than 100 MPN/g. PvuII successfully discriminated sausage isolates with a Simpson's numerical index of discrimination of 0.637. A total of 12 and 9 different PvuII ribogroups were identified among 47 fresh and 24 fermented randomly selected sausage strains, respectively. Six of those ribogroups were shared between strains contaminating both kinds of sausages. According to the evaluation of the strain DUP-IDs, the majority of the isolates investigated in this study were part of the type II L. monocytogenes pathogenicity lineage, but type I lineage strains were identified among fermented sausage isolates. In conclusion, L. monocytogenes prevalence in Italian sausages was estimated to be around 28.2%. However, 84.2% of the samples were contaminated by less than 100 MPN of L. monocytogenes per g and the majority of L. monocytogenes contaminating strains would be classified in the type II pathogenicity lineage, including serotypes 1/2a, 1/2c and 3a.     

Curcumin and the cellular stress response in free radical-related diseases

Free radicals play a main pathogenic role in several human diseases such as neurodegenerative disorders, diabetes, and cancer. Although there has been progress in treatment of these diseases, the development of important side effects may complicate the therapeutic course. Curcumin, a well known spice commonly used in India to make foods colored and flavored, is also used in traditional medicine to treat mild or moderate human diseases. In the recent years, a growing body of literature has unraveled the antioxidant, anticarcinogenic, and antinfectious activity of curcumin based on the ability of this compound to regulate a number of cellular signal transduction pathways. These promising data obtained in vitro are now being translated to the clinic and more than ten clinical trials are currently ongoing worldwide. This review outlines the biological activities of curcumin and discusses its potential use in the prevention and treatment of human diseases.     

Solving non-linear elliptic difference equations by extendable sparse factorization procedures

New extendable LU sparse factorization procedures are presented for the solution of non-linear elliptic difference equations. The derived iterative methods are shown to be both competitive and computationally efficient in comparison with existing schemes. Application of the methods on non-linear elliptic boundary value problems both in two and three space dimensions are discussed and numerical results are given.     

Some basic results on M-matrices in connection with the Accelerated Overrelaxation (AOR) method

This paper extends some recent results by Varga concerning the theory of M-matrices, in connection with the well known iterative methods of Jacobi, of Extrapolated Jacobi and of Successive Over-relaxation, in two directions: i) The iteration matrix of the iterative scheme considered is more general than that of the aforementioned methods and may include a diagonal part and ii) the theory is presented in such a way that the number of equivalent statements given in the text covers the Accelerated Overrelaxation (AOR) method introduced by the present author not long ago.     

Numerische Lösung gewöhnlicher Differentialgleichungen mit Splinefunktionen

In this paper a general procedure to obtain spline approximations for the solutions of initial value problems for ordinary differential equations is presented. Several well-known spline approximation methods are included as special cases. It is common practice to partition the interval for which the initial value problem is defined into equidistant subintervals and to construct successively the spline approximation; thereby the spline function has to satisfy certain conditions at the knots. In the general procedure presented here additional knots are admitted in every subinterval. At these points which need not be equally spaced the spline approximation has to fulfill analogous conditions as at the original knots. Convergence and divergence theorems are proved; especially the influence of the additional knots on convergence and divergence of the method is investigated.     

Computing turning points of curves implicitly defined by nonlinear equations depending on a parameter

Let the space curveL be defined implicitly by the (n, n+1) nonlinear systemH(u)=0. A new direct Newton-like method for computing turning points ofL is described that requires per step only the evaluation of one Jacobian and 5 function values ofH. Moreover, a linear system of dimensionn+1 with 4 different right hand sides has to be solved per step. Under suitable conditions the method is shown to converge locally withQ-order two if a certain discretization stepsize is appropriately chosen. Two numerical examples confirm the theoretical results.     

On real factorizations of symmetric circulant sparse matrices

For the matricesA mentioned in the headline we determine the limit points up to which there is possible a real factorization of the formA=QQ ^T . HereQ=(q _ij ) is a circulant matrix, where from the elementsq _ij andq _ji withi≠j always one element is vanishing.     

Food safety education makes the difference: food safety perceptions, knowledge, attitudes and practices among Turkish university students

This study evaluated the influence of food safety education on the food safety perceptions, knowledge, attitudes, and practices among Turkish university students. Structured questionnaires were applied to 275 students majoring in “health or food” and 570 students majoring in “non-health or non-food” on a face-to-face basis. Food has positive connotations since associated primarily with taste and hunger in both groups. Freshness of the food product was the most important factor for the “health or food major” group, which was stated as quality for the “non-health or non-food major” group, when shopping for food (p < 0.05). Food poisoning was the main risk associated with foods in the “health or food major” group whereas fats was the most popular choice for the same question in the other group (p < 0.05). Positive influence of food safety education was clear from the results since a significant difference existed between the mean scores of knowledge, attitudes, and practices according to major discipline (p < 0.05). However, persistent food safety attitudes and practices showed little improvement with education. Although a significant difference existed between the disciplines, students in both groups did not have knowledge on the risk of raw white cheese consumption (p < 0.0001). High number of students shared their bowls with other people, consumed raw eggs and raw meat, and ate cooked foods left at room temperature more than 6 h if covered. Scientists and doctors were more trusted sources of information about serious food risks (p < 0.05). Trust in governmental agencies was significantly less in both groups.