Low prevalence of Listeria monocytogenes in foods from Italy

Listeria monocytogenes is an important foodborne pathogen that causes gastrointestinal disorders, and, especially in immunocompromised people, serious extraintestinal diseases, such as septicemia and meningitis, as well as abortion in pregnant women. Many foods, from both plant and animal origin, have been involved in listeriosis outbreaks. This article reports the results of a 12-year survey (1993 through 2004) on the presence of L. monocytogenes in several kinds of food marketed in Italy. Of 5,788 analyzed samples, 121 (2.1%) were contaminated with L. monocytogenes. The highest prevalence was found in smoked salmon (10.6%) and in poultry meat samples (8.5%) and the lowest in red meat (0.3%). L. monocytogenes was not found in 154 samples of fresh seafood products. Fifty-two isolates were also serotyped by the agglutination method. The most common serotypes detected in the 52 strains tested were 1/2a (36.5%), followed by 1/2c (32.8%), 1/2b (13.5%), 4b (11.5%), 3a (3.8%), and 3b (1.9%). The results of the present study showed low levels of L. monocytogenes in the analyzed samples. A total of 61.5% of the 52 L. monocytogenes strains analyzed belonged to serotypes 1/2a, 1/2b, and 4b, namely the serovars that are most commonly involved in extraintestinal human listeriosis outbreaks. In the ready-to-eat samples, these three serotypes were 40.0% (1/2a), 17.1% (1/2b), and 14.3% (4b). This finding highlights the need to implement strict hygienic measures during the production, distribution, and sale of foods to reduce the risk of foodborne listeriosis in humans to an acceptable level.     

Enterococcus populations in Pecorino Abruzzese cheese: biodiversity and safety aspects

The presence of enterococci in Pecorino Abruzzese cheese during ripening was evaluated. Counts were high, especially in fully ripened summer batches. Seventy strains were isolated and identified based on phenotypical and genotypical features as Enterococcus faecium (48.5%), Enterococcus faecalis (40%), and Enterococcus durans (11.5%), with the first species predominant in spring batches and the second predominant in summer batches. High biodiversity was revealed by random amplification of polymorphic DNA and a PCR assay, suggesting the presence of autochthonous strains. E. faecium isolates were the most resistant to the tested antibiotics, especially to erythromycin, chloramphenicol, and penicillin, but all strains were susceptible to vancomycin, as confirmed by the absence of vanA and vanB genes. The presence of some virulence determinants was investigated, revealing the diffusion of aggregation substance (asal) and gelatinase (gelE) genes in 37.5% of E. faecalis strains. However, none of the isolates produced gelatinase in vitro, suggesting the presence of silent genes. The virulence genes were absent in E. durans. Among E. faecium strains, only Lab 41/1 possessed gelE and asal, whose presence previously has been reported only in E. faecalis. Decarboxylating activity was revealed for phenylalanine (27% of the strains) and tyrosine (96%) but not histidine. The presence of a tyrosine decarboxylase-encoding gene was observed for all strains. A comparison of these results with those of previous studies of clinical and food isolates indicates that enterococci from Pecorino Abruzzese cheese have low pathogenic potential.     

Influence of grape variety and their phenolic composition on vasorelaxing activity of young red wines

Red wine has been reported to exert beneficial effects in preventing cardiovascular diseases probably due to their polyphenols constituents. The vasorelaxant capacity and phenolic composition of four monovarietal young red wines Merlot, Tempranillo, Garnacha and Cabernet-Sauvignon obtained from grapes from 2004 vintage, cultivated under the same climatic and agricultural conditions, wine-making technology and storage conditions, were determined using vascular reactivity assay in rat aortic and high-performance liquid chromatography, respectively. Primary cultures of vascular smooth muscle cells from Wistar rats were also used to evaluate their survival prevention activity as well. Every studied wine present vasorelaxation effect, but the higher value corresponds to the analyzed Merlot wine, especially rich in phenolic compounds, mainly catechins and oligomeric proanthocyanidins and anthocyanin glycosides. This study further demonstrated previous investigations about the phenolic composition of wines relation with their vasorelaxation activity.     

Conditions for stability of the extended Kalman filter and their application to the frequency tracking problem

The error dynamics of the extended Kalman filter (EKF), employed as an observer for a general nonlinear, stochastic discrete time system, are analyzed. Sufficient conditions for the boundedness of the errors of the EKF are determined. An expression for the bound on the errors is given in terms of the size of the nonlinearities of the system and the error covariance matrices used in the design of the EKF. The results are applied to the design of a stable EKF frequency tracker for a signal with time-varying frequency.This research was supported by the Co-operative Research Centre for Robust and Adaptive Systems ((CR)² ASys). The authors wish to acknowledge the funding of the activities of (CR)² ASys by the Australian Commonwealth Government under the Co-operative Research Centre Program.     

Spectral estimation by least-squares optimization based on rational covariance extension

This paper proposes a new spectral estimation technique based on rational covariance extension with degree constraint. The technique finds a rational spectral density function that approximates given spectral density data under constraint on a covariance sequence. Spectral density approximation problems are formulated as nonconvex optimization problems with respect to a Schur polynomial. To formulate the approximation problems, the least-squares sum is considered as a distance. Properties of optimization problems and numerical algorithms to solve them are explained. Numerical examples illustrate how the methods discussed in this paper are useful in stochastic model reduction and stochastic process modeling.     

Effect of fat-enriched diets on rabbit meat fatty acid composition

The effects of beef tallow-, soya and sunflower olein- and soya bean oil-enriched (3%) diets on the chemical and fatty acid composition of total, a polar and polar lipids of rabbit meat have been studied. No significant differences (P > 0.05) in the meat chemical composition were observed between groups. However, a large effect of the diet on the total and apolar lipid fatty acids was found, with C18:1 and C18:2 the most affected fatty acids. The influence of the diets on the fatty acids of the polar fraction was less marked. It is concluded that the enrichment of the rabbit diet with either soya and sunflower oleins or soya bean oil allows the production of rabbit meat with a higher unsaturation degree than is obtained by using conventional diets, which constitutes an important nutritional benefit to the human being.     

Recent Advances in Hydroxyapatite-Based Biocomposites for Bone Tissue Regeneration in Orthopedics

Bone tissue is a nanocomposite consisting of an organic and inorganic matrix, in which the collagen component and the mineral phase are organized into complex and porous structures. Hydroxyapatite (HA) is the most used ceramic biomaterial since it mimics the mineral composition of the bone in vertebrates. However, this biomimetic material has poor mechanical properties, such as low tensile and compressive strength, which make it not suitable for bone tissue engineering (BTE). For this reason, HA is often used in combination with different polymers and crosslinkers in the form of composites to improve their mechanical properties and the overall performance of the implantable biomaterials developed for orthopedic applications. This review summarizes recent advances in HA-based biocomposites for bone regeneration, addressing the most widely employed inorganic matrices, the natural and synthetic polymers used as reinforcing components, and the crosslinkers added to improve the mechanical properties of the scaffolds. Besides presenting the main physical and chemical methods in tissue engineering applications, this survey shows that HA biocomposites are generally biocompatible, as per most in vitro and in vivo studies involving animal models and that the results of clinical studies on humans sometimes remain controversial. We believe this review will be helpful as introductory information for scientists studying HA materials in the biomedical field.     

Accuracy of FIB-4 to Detect Elevated Liver Stiffness Measurements in Patients with Non-Alcoholic Fatty Liver Disease: A Cross-Sectional Study in Referral Centers

The identification of advanced fibrosis by applying noninvasive tests is still a key component of the diagnostic algorithm of NAFLD. The aim of this study is to assess the concordance between the FIB-4 and liver stiffness measurement (LSM) in patients referred to two liver centers for the ultrasound-based diagnosis of NAFLD. Fibrosis 4 Index for Liver Fibrosis (FIB-4) and LSM were assessed in 1338 patients. A total of 428 (32%) had an LSM ≥ 8 kPa, whereas 699 (52%) and 113 (9%) patients had an FIB-4 < 1.3 and >3.25, respectively. Among 699 patients with an FIB-4 < 1.3, 118 (17%) had an LSM ≥ 8 kPa (false-negative FIB-4). This proportion was higher in patients ≥60 years, with diabetes mellitus (DM), arterial hypertension or a body mass index (BMI) ≥ 27 kg/m². In multiple adjusted models, age ≥ 60 years (odds ratio (OR) = 1.96, 95% confidence interval (CI) 1.19–3.23)), DM (OR = 2.59, 95% CI 1.63–4.13), body mass index (BMI) ≥ 27 kg/m² (OR = 2.17, 95% CI 1.33–3.56) and gamma-glutamyltransferase ≥ 25 UI/L (OR = 2.68, 95% CI 1.49–4.84) were associated with false-negative FIB-4. The proportion of false-negative FIB-4 was 6% in patients with none or one of these risk factors and increased to 16, 31 and 46% among those with two, three and four concomitant risk factors, respectively. FIB-4 is suboptimal to identify patients to refer to liver centers, because about one-fifth may be false negative at FIB-4, having instead an LSM ≥ 8 KPa.     

Application of chemical equilibrium for hydrocarbon isomerization analysis

Isomerization is used in refining industry to upgrade gasoline. Since it is an important process, it is desirable to analyze the reactions that take place in the process. In this paper, the isomerization of a mixture of hydrocarbons was modeled by solving the chemical equilibrium of the system. A direct application of the chemical equilibrium solution cannot reproduce experimental results. However, when some of the system reactions are molar extent limited, the solution can reproduce published experimental data.     

Two-step sinter-crystallization of K2O–CaO–P2O5–SiO2 (45S5-K) bioactive glass

Bioactive glasses and glass-ceramics (GCs) effectively regenerate bone tissue, however most GCs show improved mechanical properties. In this work, we developed and tested a rarely studied bioactive glass composition (24.4K₂O-26.9CaO-46.1SiO₂-2.6P₂O₅ mol%, identified as 45S5-K) with different particle sizes and heating rates to obtain a sintered GC that combines good fracture strength, low elastic modulus, and bioactivity. We analyzed the influence of the sintering processing conditions in the elastic modulus, Vickers microhardness, density, and crystal phase formation in the GC. The best GC shows improved properties compared with its parent glass. This glass achieves a good densification degree with a two-step viscous flow sintering approach and the resulting GC shows as high bioactivity as that of the standard 45S5 Bioglass®. Furthermore, the GC elastic modulus (56 GPa) is relatively low, minimizing stress shielding. Therefore, we unveiled the glass sintering behavior with concurrent crystallization of this complex bioactive glass composition and developed a potential GC for bone regeneration.