Antimicrobial resistance of 914 beta-hemolytic streptococci isolated from pharyngeal swabs in Spain: results of a 1-year (1996-1997) multicenter surveillance study. The Spanish Surveillance Group for Respiratory Pathogens

A nationwide susceptibility surveillance study of beta-hemolytic streptococcal isolates from pharyngeal swabs obtained in 11 Spanish hospitals between May 1996 and April 1997 against 12 antibiotics was carried out. Of the isolates 86% (786 of 914 isolates) were group A and 8.4% (77 of 914 isolates) were group C. No resistance was found to beta-lactam antibiotics, but significant differences (P < 0.001) with respect to lack of susceptibility to macrolides were found between groups (27% for group A and 12% for group C) and between seasons (13.2% in summer and 31.7% in winter). Most of these isolates displayed the M phenotype (low-level resistance to erythromycin and susceptibility to clindamycin).     

Molecular crowding and viscosity as determinants of translational diffusion of metabolites in subcellular organelles

The role of molecular crowding and viscosity on the apparent translational diffusion coefficient (ADC) of small metabolites was investigated in different subcellular organelles using the pulse-field gradient spin-echo 1H NMR technique. ADCs of metabolites with increasing radius of gyration (0.7 A < RG < 4.5 A) were measured in the cytoplasm of rat or chicken erythrocytes, in the nucleus of chicken erythrocytes, and in isolated rat liver mitochondria. Metabolite ADCs in these systems were compared with the corresponding ADCs determined in model solutions of increasing bulk viscosity but different molecular crowding. For solutions having the same viscosity, metabolite ADCs decreased with increasing concentration of cosolutes. This effect is adequately described by the modified Stokes-Einstein relationship, ADC = k/RG (1 + 2.5Phi), where k is a constant for a given temperature and Phi is an obstruction factor reporting the fractional volume of solution occupied by cosolutes, a measure of the molecular crowding in the solution. Cytoplasmic values of Phi for metabolites of different sizes did not depend exclusively on metabolite RG but on additional factors including the chemical nature of the metabolite, the presence of diffusional barriers, and metabolite-specific binding sites. In the case of water, nuclear Phi values approached those of the extracellular space while mitochondrial Phi values were significantly higher than those of the cytoplasm. Taken together, these results reveal important differences in molecular crowding within the different subcellular compartments, suggesting considerable diffusional heterogeneity for small metabolites within the different intracellular organelles.     

EGF stimulates tyrosine phosphorylation of focal adhesion kinase (p125FAK) and paxillin in rat pancreatic acini by a phospholipase C-independent process that depends on phosphatidylinositol 3-kinase, the small GTP-binding protein, p21rho, and the integrity of the actin cytoskeleton

Epidermal growth factor (EGF) is a potent mitogen in many cell types including pancreatic cells. Recent studies show that the effects of some growth factors on growth and cell migration are mediated by tyrosine phosphorylation of the cytosolic tyrosine kinase p125 focal adhesion kinase (p125FAK) and the cytoskeletal protein, paxillin. The aim of the present study was to determine whether EGF activates this pathway in rat pancreatic acini and causes tyrosine phosphorylation of each of these proteins, and to examine the intracellular pathways involved. Treatment of pancreatic acini with EGF induced a rapid, concentration-dependent increase in p125FAK and paxillin tyrosine phosphorylation. Depletion of the intracellular calcium pool or inhibition of PKC activation had no effect on the response to EGF. However, inhibition of the phosphatidylinositol 3-kinase (PI3-kinase) or inactivation of p21rho inhibited EGF-stimulated phosphorylation of p125FAK and paxillin by more than 70%. Finally, cytochalasin D, a selective disrupter of the actin filament network, completely inhibited EGF-stimulated tyrosine phosphorylation of both proteins. All these treatments did not modify EGF receptor autophosphorylation in response to EGF. These results identify p125FAK and paxillin as components of the intracellular pathways stimulated after EGF receptor occupation in rat pancreatic acini. Activation of this cascade requires activation of PI3-kinase and participation of p21rho, but not PKC activation and calcium mobilization.     

Identification of the occluded artery in patients with myocardial ischemia induced by prolonged percutaneous transluminal coronary angioplasty using traditional vs transformed ECG-based indexes.

We have studied the spatial properties of ischemic changes as induced by prolonged angioplasty and how the changes are related to different ECG indexes. Indexes based on measurements at specific points in time (ST level at J + 60 ms point, maximal T wave amplitude and position, QT interval, and QRS duration) and global indexes (based on the Karhunen-Loève transform and applied to the QRS complex, ST-T complex, ST segment, and T wave), considering both repolarization and depolarization information, were analyzed. The changes during the occlusion period of the different indexes were used as variables in a multivariate discriminant analysis to determine which indexes showed the best discrimination of the three major occlusion sites (corresponding to LAD, RCA, and LCX coronary arteries). Occlusions in LCX artery were the most difficult to classify. With three local indexes (ST60 level measured in lead V3, T wave amplitude in I, and ST60 in III) it was possible to correctly classify 76% of patients by the occlusion site, and with three KLT-derived indexes (first-order KLT index for ST-T complex in I and for QRS in leads V3 and I) 83% of correct classification was obtained. Using six indexes for local and KLT-derived indexes the correct classification was increased to 85 and 90% of patients, respectively. The use of different ECG indexes (from different intervals) on quasiorthogonal leads permitted the identification of the occluded artery in patients undergoing PTCA and may be extended to more general use.     

Thermoluminescent behaviour of diamond films subjected to UV irradiation

The thermoluminescent behaviour of diamond films subjected to UV irradiation was studied by using an UV lamp of 254 nm wavelength. The UV irradiation was achieved by placing the samples 15 cm away from an UV source for different periods. The thermoluminescent signal was integrated from 0 to 350°C at a linear heating rate of 10°C/s in a N₂ atmosphere. The corresponding luminescence spectra show an excitation band centered at 450 nm while the emission band is centered around 500 nm at room temperature. The diamond films were synthesized on molybdenum substrates by the combustion flame technique and characterized by Raman spectroscopy and scanning electron microscopy. Received: 31 May 1999 / Reviewed and accepted: 22 July 1999     

Searching potential candidates for development of protective cultures: Evaluation of two Lactobacillus strains to reduce Listeria monocytogenes in artificially contaminated milk

The aims of this work were (a) to select the minimum concentrations of two bacteriocin-producing lactobacilli strains to reduce Listeria monocytogenes growth in whole milk, (b) to evaluate the individual and combined application of these chosen lactobacilli concentrations as protective culture in this food and, (c) to estimate if lactobacilli growth caused undesirable changes in the visible characteristics of milk. The selected minimum lactobacilli concentration with antilisterial activity was 10⁶ CFU ml⁻¹ for both lactobacilli. Although a high initial concentration of L. monocytogenes (10⁴ CFU ml⁻¹) was added to milk, a notable reduction on listerial counts (2–4 log CFU ml⁻¹) was achieved in comparison to the control. These lactobacilli showed a good adaptability in milk reaching optimal counts and not causing undesirable visible changes. In conclusion, the use of these lactobacilli could be considered as a bio-strategy potentially effective to limit the contamination by L. monocytogenes in certain milk-derived products.