Evaluation of genetic polymorphism among Lactobacillus rhamnosus non-starter Parmigiano Reggiano cheese strains

Parmigiano Reggiano (PR) is an Italian cooked, long-ripened cheese made with unheated cow's milk and natural whey starter. The microflora is involved in the manufacturing of this cheese, arising from the natural whey starter, the raw milk and the environment. Molecular studies have shown that mesophilic non-starter lactic acid bacteria (NSLAB) are the dominant microflora present during the ripening of PR. In this study, a characterisation of Lactobacillus rhamnosus isolated from a single PR manufacturing and ripening process is reported, using a combination of genotypic fingerprinting techniques (RAPD-PCR and REP-PCR). The intraspecies heterogeneity evidenced for 66 strains is correlated to their abilities to adapt to specific environmental and technological conditions. The detection of biotypes that correlate with specific moments in cheese ripening or differential development throughout this process suggests that these strains may have specific roles closely linked to their peculiar technological properties.     

Revised stability analysis of the nonlinear Poisson scheme in self-consistent Monte Carlo device simulations

In this paper, the stability of self-consistent Monte Carlo (MC) device simulations is revised by developing a model that extends the existing ones by accounting for the effect of a carrier diffusion. Both the linear and the nonlinear Poisson schemes have been considered. The analysis of the linear Poisson scheme reveals that, consistently with the available model, the time step between two Poisson solutions must be short compared to a factor proportional to the scattering rate. On the other hand, it has been found that, contrary to the available stability models, the nonlinear Poisson scheme requires long time steps in order to provide stable simulations. For this reason, the nonlinear scheme is advantageous when considering steady-state simulations. The model predictions have been verified by comparison with MC simulations implementing both schemes.     

Kininogen-derived fluorogenic substrates for investigating the vasoactive properties of rat tissue kallikreins--identification of a T-kinin-releasing rat kallikrein

Peptide substrates with intramolecularly quenched fluorescence that reproduce the rat kininogen sequences at both ends of the bradykinin moiety were synthesized and used to investigate the kinin-releasing properties of five rat tissue kallikreins (rK1, rK2, rK7, rK9, rK10). Substrates derived from rat H- and L-kininogen were cleaved best by rK1, especially that including the N-terminal insertion site of bradykinin, Abz-TSVIRRPQ-EDDnp(Abz = O-aminobenzoyl, EDDnp = ethylenediamine 2,4-dinitrophenyl), which was cleaved at the R-R bond with a k(cat)/Km of 12400 mM(-1) s(-1). Replacement of the P2' residue Pro by Val in Abz-TSVIRRPQ-EDDnp gave a far less specific substrate that was rapidly hydrolysed by all five rat kallikreins and human kallikrein hK1. Peptidyl-N-methyl coumarylamide substrates, which lack prime residues, also had low specificities. The importance of the P2' residue for rK1 specificity was further demonstrated using a human-kininogen-derived substrate that included the N-terminal insertion site of bradykinin (Abz-LMKRP-EDDnp). This was cleaved at the M-K bond by hK1 (kallidin-releasing site), but at the K-R bond (bradykinin-releasing site) by rK1. Competition experiments with Abz-TSVIRRPQ-EDDnp, which is resistant to most kallikreins, and Abz-TSVIRRVQ-EDDnp, a general kallikrein substrate, demonstrated that the former competitively inhibited hydrolysis by rK9 and hK1, with Ki values similar to the Km values for the substrate. Thus Pro in P2' does not prevent the peptide binding to the enzyme active site, but impairs cleavage of the scissile bond. The T-kininogen-derived substrate with the T-kinin C-terminal sequence (Abz-FRLVR-EDDnp) was cleaved by rK10 (k(cat)/Km = 2310 mM(-1) s(-1)) and less rapidly by rK1, rK7 and hK1, at the R-L bond, while that corresponding to the N-terminal (Abz-ALDMMISRP-EDDnp) of T-kinin was resistant to all five kallikreins used, suggesting that none has T-kininogenase activity. But this substrate was hydrolysed by a semipurified sample of submandibular gland extract. Another kallikrein, identified as kallikrein rK3, was isolated from this fraction and shown to hydrolyze Abz-ALDMMISRP-EDDnp; rK3 also specifically released T-kinin from purified T1/T2-kininogen after HPLC fractionation. Injection of purified rK3 and of Abz-ALDMMISRP-EDDnp-cleaving fractions into the circulation of anesthesized rats caused transient falls in blood pressure, as did purified rK1 but none of the other purified rat or human kallikreins. This effect occurred via activation of the kinin system since it was blocked by Hoe140, a kinin receptor antagonist.     

Fatty acid composition of rice oils.

Analysis of rice oil methyl esters of two varieties by gas-liquid chromatography showed that oil from bran-polish and oil from milled rice extracted with petroleum ether had similar fatty acid composition and had oleic/linoleic acid ratios of about 1.0. However, milled rice oil extracted with chloroform/methanol had a higher linoleic acid content and a lower oleic acid content than oil extracted with petroleum ether.     

Comparative analysis of humoral immune responses to HIV type 1 envelope glycoproteins in mice immunized with a DNA vaccine, recombinant Semliki Forest virus RNA, or recombinant Semliki Forest virus particles

The Semliki Forest virus (SFV) system seems to be a useful new approach for generating effective immune responses against HIV-1 in animal models. We evaluated this system by comparing the humoral immune responses raised in mice immunized against the HIV-1 envelope with the SFV system, a DNA vaccine, and a recombinant Env glycoprotein. gp160 ELISA antibody titers (204,800) were highest in the sera from mice immunized with recombinant Semliki Forest virus particles. These sera contained antibodies to the CD4-binding site and recognized linear epitopes on gp120 and gp41 that were also recognized by a pool of sera from HIV1-infected individuals. This demonstrates that the HIV-1 envelope produced in vivo by the SFV system does not fold aberrantly. A low level of neutralizing antibodies against the HIV-1LAI strain was also detected in the serum of one mouse immunized with recombinant SFV particles, suggesting that booster injections should be given to achieve a more effective immune response. SFV recombinant particles induced the strongest humoral responses to the HIV-1 envelope of all the potential HIV env vaccines tested.     

Nitrogen balance in rats fed rices differing in protein content

Nitrogen balance was studied in rats fed seven milled rice samples with 1.10 to 2.73% N dry basis. True digestibility (t.d.) of the protein ranged from 94.4 to 100.1%, biological value (b.v.) ranged from 67.9 to 75.2% and net protein utilisation (n.p.u.) from 64.2 to 75.3%. T.d. and n.p.u. were positively correlated with lysine content of rice protein (3.17 to 4.07 g/16 g of N). Utilisable N ranged from 0.83 to 1.81% and was mainly determined by N content of milled rice (r = 0.988**). A sample of brown rice had lower t.d. but higher b.v. than the corresponding milled rice. Digestibility of amino acids of milled rice protein by fae al analysis ranged from 94.1 to 100.0% in samples with 1.38 and 2.74% N dry basis.     

Combined application of electrolysed water and ultrasound to improve the sanitation of knives in the meat industry

This study investigated the effect of the combination of basic electrolysed water (BEW) and slightly acid electrolysed water (SAEW) with ultrasound (US) for cleaning and sanitation of the knives used in slaughtering processes. The knives were sonicated in a US bath using two modes of operation (normal and sweep) in two steps: (i) 5 min with BEW and (ii) 10 min with SAEW at 35 °C. The microbiological counts and the possible changes in the physical structure of the knives were evaluated. The association BEW + SAEW + US, in the sweep mode, provided lower mesophilic, enterobacterial, Staphylococcus aureus and yeast counts when compared to the values recommended by the international legislation. In addition, these conditions removed all organic residues from the knife blades and promoted the highest migration rate of the residues to the US water bath (12.35 mg/L·min), without modifications in the knife blades. Thus, cleaning and sanitation of knives was feasible with the association of BEW + SAEW + US, which could be a useful alternative for the meat industry.