Specific Bifidobacterium strains isolated from elderly subjects inhibit growth of Staphylococcus aureus

Cell-free, pH-controlled supernatants of thirty-eight Bifidobacterium strains isolated from healthy elderly subjects were subjected to antimicrobial activity assay. Bioluminescent indicator strains Staphylococcus aureus RN4220, Escherichia coli K-12, and Salmonella enterica serovar Typhimurium ATCC 14028 were used as targets of antimicrobial activity. The effect of nutrient depletion on the inhibition was eliminated with spent-culture controls. Three out of thirty-eight Bifidobacterium strains were capable of inhibiting the growth of S. aureus. The inhibition was equal to 23.2+/-19.1% to 50.4+/-26.7% of the inhibition caused by 50 IU/ml nisin. Reuterin-producing positive strain Lactobacillus reuteri SD2112 was capable of 86.0+/-24.6% inhibition, but Bifidobacterium lactis Bb-12, a known probiotic strain, showed no inhibition. None of the strains was capable of inhibiting the growth of E. coli or S. enterica. The observed inhibition by bifidobacteria was related to hydrogen peroxide formation and possible production of heat-stable proteinaceous compounds. The results suggest that production of antimicrobial substances other than organic acids is not common among Bifidobacterium strains typical of elderly subjects. However, specific strains were identified which showed considerable inhibitory activity against S. aureus.     

Safety assessment of Lactobacillus strains: presence of putative risk factors in faecal, blood and probiotic isolates

The widespread use of immunosuppressive therapy and antimicrobial agents as well as novel probiotics without a long history of safe use has increased requirements for safety assessment of probiotic lactobacilli. In this study 44 faecal, 52 blood and 15 probiotic isolates (including 3 dairy strains) of Lactobacillus were assayed for their adhesion properties to extracellular matrix proteins and mucus, hemolysis, ability to avoid the induction of respiratory burst in peripheral blood mononucleocytes (PMN) and resistance to human serum. Among tested strains adhesion to collagen, fibrinogen and mucus was isolate-specific and no statistically significant differences were obtained between faecal, blood and probiotic isolates. However, blood isolates showed a trend for higher adhesion to mucus than probiotic strains (P=0.07). Probiotic strains induced lower respiratory burst in PMN when compared to the blood isolates (P<0.05). Moreover, there was a positive correlation between adhesion to collagen and induction of respiratory burst for faecal isolates (P<0.05). In the determination of serum resistance, probiotic strains showed a trend for lower sensitivity to human serum-mediated killing when compared to the faecal isolates (P=0.07). None of the measurable virulence factors were found to be present at statistically higher level in clinical blood isolates when compared to faecal and/or probiotic isolates indicating that these factors do not cause risk when safety of probiotics is considered. However, the significance of adhesion to mucus, low induction of respiratory burst in PMN and resistance to human serum-mediated killing may need further evaluation in experimental animal models and in epidemiological data.     

Thermodynamic Evaluation of Inclusions Formation and Behaviour in Steels during Casting and Solidification

For demanding applications high steel cleanliness and strictly controlled inclusions are required. Primary inclusions are formed during steel treatments in the ladle. Most of these are removed to the ladle slag or on the lining. However, the rest of the inclusions still remain through the successive process stages, and additionally new inclusions are formed during casting and solidification due to decreasing thermodynamic solubility of oxygen in the steel at lower temperatures, reactions with surrounding slag, refractory materials and eventual contact with air. Inclusions formation and transformation are simulated by thermodynamic calculations in the steel/inclusions/slag system taking into account the solidification phenomena. In this paper inclusions in Si/Mn‐deoxidised steel and Al‐deoxidised Ca‐treated steels are contributed. Calculations are compared with experimental results from steel plants.     

A Model for Predicting the Melt Temperature in the Ladle and in the Tundish as a Function of Operating Parameters during Continuous Casting

A mathematical model for predicting the melt temperatures in the ladle and in the tundish during continuous casting has been developed. First of all, a chain of models was created for the following stages of the ladle cycle; the preheating of the empty ladle, filling of the ladle, period in the ladle furnace, waiting period prior to casting, the casting period, and, finally, the free cooling period of the empty ladle. Models, written in CFD code, were used in sequence so that each simulation continued from the results of the simulation of the previous stage. An intermediate model was constructed to estimate the outlet temperature of melt drained from the ladle. Then the work was continued by performing simulations in the tundish, using as input the temperature of the simulated melt feed from the ladle and, as an initial condition, the temperature field of the remaining melt in the tundish. The final model “TEMPARV3” was created and tested by means of measured tundish data received from a steel plant. By means of statistical analysis the coefficients of correlation between the test data and model data at the start, in the middle period, and at the end of casting were calculated to be 0.9, 0.92 and 0.87, respectively. So, the most effective predictive power of the model in the tundish by means of a sequential casting schedule is realized during the middle period of the casting process. The model is applied interactively by a user interface, which expresses the predicted melt temperatures numerically and with graphical curves. The predictive model can be used off‐line as a tool for scheduling the stage operations in advance. The program may be utilized on‐line to estimate the superheat needed and to control periods of the operation. In extreme cases, when the model alerts the operator about the danger of superheat loss having a critical effect on casting, the operator has a chance to take adjustment measures. In addition to production work, the model could be of benefit for studying changes in operating parameters, for training operators, and for use as a “low‐cost computational pilot plant” in process development in general.     

On the realization of periodic functions

In this article, canonical and spectrally minimal infinite-dimensional state space realizations for periodic functions are considered. It is shown that the periodic functions having ℓ₁ Fourier coefficients are precisely those realizable by a Riesz spectral system (RSS) in which the system operator generates a periodic strongly continuous semigroup and the observation operator is bounded. This realization can easily be converted to a canonical and spectrally minimal form. It is shown how the use of RSS and Cesáro sums of Fourier series allows the construction of a state space realization for a given periodic function merely integrable over its period. Simple finite-dimensional approximations with error bounds are derived for the RSS realization. Regular well-posed linear systems (WPLS) are used to construct a Fuhrmann-type realization for a given periodic function integrable over its period. It is shown that the RSS realizations and WPLS realizations are precisely equally good at coping with the possible ill behavior of a given bounded periodic function integrable over its period, but the WPLS realization is not always spectrally minimal or canonical.     

Microchip atmospheric pressure chemical ionization source for mass spectrometry

A novel microchip heated nebulizer for atmospheric pressure chemical ionization mass spectrometry is presented. Anisotropic wet etching is used to fabricate the flow channels, inlet, and nozzle on a silicon wafer. An integrated heater of aluminum is sputtered on a glass wafer. The two wafers are jointed by anodic bonding, creating a two-dimensional version of an APCI source with a sample channel in the middle and gas channels symmetrically on both sides. The ionization is initiated with an external corona-discharge needle positioned 2 mm in front of the microchip heated nebulizer. The microchip APCI source provides flow rates down to 50 nL/min, stable long-term analysis with chip lifetime of weeks, good quantitative repeatability (RSD < 10%) and linearity (r(2) > 0.995) with linear dynamic rage of at least 4 orders of magnitude, and cost-efficient manufacturing. The limit of detection (LOD) for acridine measured with microchip APCI at flow rate of 6.2 muL/min was 5 nM, corresponding to a mass flow of 0.52 fmol/s. The LOD with commercial macro-APCI at a flow rate of 1 mL/min for acridine was the same, 5 nM, corresponding to a significantly worse mass flow sensitivity (83 fmol/s) than measured with microchip APCI. The advantages of microchip APCI makes it a very attractive new microfluidic detector.     

Rapid Development of Fasting-Induced Hepatic Lipidosis in the American Mink (<Emphasis Type=Italic>Neovison vison</Emphasis>): Effects of Food Deprivation and Re-Alimentation on Body Fat Depots,Tissue Fatty Acid Profiles,Hematology and Endocrinology

Hepatic lipidosis is a common pathological finding in the American mink (Neovison vison) and can be caused by nutritional imbalance due to obesity or rapid body weight loss. The objectives of the present study were to investigate the timeline and characterize the development of hepatic lipidosis in mink in response to 0–7 days of food deprivation and liver recovery after 28 days of re-feeding. We report here the effects on hematological and endocrine variables, body fat mobilization, the development of hepatic lipidosis and the alterations in the liver lipid classes and tissue fatty acid (FA) sums. Food deprivation resulted in the rapid mobilization of body fat, most notably visceral, causing elevated hepatosomatic index and increased liver triacylglycerol content. The increased absolute amounts of liver total phospholipids and phosphatidylcholine suggested endoplasmic reticulum stress. The hepatic lipid infiltration and the altered liver lipid profiles were associated with a significantly reduced proportion of n-3 polyunsaturated FA (PUFA) in the livers and the decrease was more evident in the females. Likewise, re-feeding of the female mink resulted in a more pronounced recovery of the liver n-3 PUFA. The rapid decrease in the n-3/n-6 PUFA ratio in response to food deprivation could trigger an inflammatory response in the liver. This could be a key contributor to the pathophysiology of fatty liver disease in mink influencing disease progression.     

Measurement of Particulate Carbon in Atmospheric Aerosol in Helsinki

By means of a simple optical apparatus the levels and variations of concentrations of elemental carbon in particles were measured. Additionally, relations between variations of elemental carbon, lead, sulfate, total suspended particle, and nitrate concentrations were studied. Calibration was performed on real samples analyzed by a wet chemical method.