Effects of feeding fiber-fermenting bacteria to pigs on nutrient digestion, fecal output, and plasma energy metabolites.

Inclusion of feedstuffs with higher plant cell wall (fiber) content in swine diets has increased in recent years due to greater availability and lower cost, especially coproduct feeds, such as corn distillers dried grains with soluble (DDGS). Limitations of feeding higher fiber diets include increased fecal output, which can exceed manure storage volumes, and decreased energy density, which can decrease growth performance; dietary treatments that ameliorate these limitations would benefit pork producers. Grower pigs (n = 48; 61.1 kg initial BW) were used to establish the effects of supplementation of fiber-fermenting bacteria in a 2 × 4 factorial, consisting of 2 diets (standard and high fiber) and 4 bacterial treatments (A, no bacteria; and B, C, and D bacterial supplements). Increased fiber came from inclusion of soybean hulls (10%) and corn DDGS (20%) in the diet. The 3 bacterial supplements (all Bacteroides strains) were isolated from fecal enrichment cultures and selected for their fiber-fermenting capacity. The high fiber diet increased fecal output, blood cholesterol, and triglyceride concentrations, and digestibility of NDF, ADF, and S; CP digestibility decreased (P ≤ 0.10). The improved fiber digestibility and altered energy status of pigs fed the high fiber diet was primarily due to fermentation of soybean hulls, resulting in increased short-chain fatty acid production and absorption, and decreased dietary starch content. Overall, pigs fed the bacterial treatments had only increased blood cholesterol concentrations (P = 0.10). When individual bacterial treatments were compared, pigs fed Bacteria B had decreased fecal output (P ≤ 0.10) and both blood glucose and cholesterol concentrations were increased (P ≤ 0.10) compared with the other 3 treatments, indicating an improved energy status. Pigs fed Bacteria B increased both CP and ADF (P ≤ 0.10), and tended (P = 0.16) to have increased NDF digestibilities compared with pigs fed no bacteria (Treatment A), whereas pigs fed the other 2 bacterial treatments did not differ from pigs fed Bacteria B for nutrient digestibility. Both had similar fecal outputs to pigs fed no bacteria. This is the first report of reduction in fecal output and increased fiber digestibility with pigs fed live bacteria. Successful application of this bacterial treatment could result in improved pig performance and decreased manure volumes, both of which would improve profitability of producers.

Lattice Boltzmann simulation of catalytic reactions.

A lattice Boltzmann model is developed to simulate finite-rate catalytic surface chemistry. Diffusive wall boundary conditions are established to account for catalytic reactions in multicomponent mixtures. Implementation of wall boundary conditions with chemical reactions is based on a general second-order accurate interpolation scheme. Results of lattice Boltzmann simulations for a four-component mixture with a global catalytic methane oxidation reaction in a straight channel are in excellent agreement with a finite volume Navier-Stokes solver in terms of both the flow field and species concentrations.

Lattice Boltzmann model for the simulation of multicomponent mixtures.

A lattice Boltzmann (LB) model for the simulation of realistic multicomponent mixtures is constructed. In the hydrodynamic limit, the LB model recovers the equations of continuum mechanics within the mixture-averaged diffusion approximation. The present implementation can be used to simulate realistic mixtures with arbitrary Schmidt numbers and molecular masses of the species. The model is applied to the mixing of two opposed jets of different concentrations and the results are in excellent agreement with a continuum model. An application to the simulation of mixtures in microflows is also presented. Results compare well with existing kinetic theory predictions of the slip coefficient for mixtures in a Couette flow.

Hydrodynamics beyond Navier-Stokes: exact solution to the lattice Boltzmann hierarchy.

The exact solution to the hierarchy of nonlinear lattice Boltzmann (LB) kinetic equations in the stationary planar Couette flow is found at nonvanishing Knudsen numbers. A new method of solving LB kinetic equations which combines the method of moments with boundary conditions for populations enables us to derive closed-form solutions for all higher-order moments. A convergence of results suggests that the LB hierarchy with larger velocity sets is the novel way to approximate kinetic theory.

Recombinant expression of indolicidin concatamers in Escherichia coli.

Antimicrobial peptides are part of the innate immune system of vertebrates and invertebrates. They are active against gram-negative and gram-positive bacteria, fungi, and protozoa. Currently, most antimicrobial peptides are extracted from host organisms or produced by solid-phase peptide synthesis. Recombinant protein expression in Escherichia coli is a tool for greater production yields at a decreased cost and reduces the use of hazardous materials. We have constructed a concatamer of indolicidin and successfully expressed a fusion product with thioredoxin in E. coli BL21DE3. Codons for methionine residues flanking individual indolicidin genes were incorporated for cyanogen bromide cleavage of the fusion protein and liberation of active monomeric indolicidin. Peptide yields of 150 microg/l monomeric indolicidin were achieved in this first report of recombinant production of indolicidin with demonstrated antimicrobial activity.

Simulation of binary mixtures with the lattice Boltzman method.

A lattice Boltzman model for the simulation of binary mixtures is presented. Contrary to previous models, the present formulation is able to simulate mixtures with different Schmidt numbers and arbitrary molecular mass ratio of the components. In the hydrodynamic limit, the Navier-Stokes and the Stefan-Maxwell binary diffusion equations are recovered. The model is used for the simulation of binary diffusion and mixing layers. The results are found to be in good agreement with a derived similarity solution and with the predictions of a transient spectral element code.

Phase change of a confined subcooled simple liquid in a nanoscale cavity.

The phase transition of a simple liquid bounded between two parallel walls a few nanometers apart is investigated with molecular dynamics simulations. Vapor nucleation in a liquid confined in a microchannel of only a few nanometers in size cannot be achieved by increasing the temperature at the wall. Already small changes in temperature cause a large rise in pressure, in terms of orders of magnitude. On the other hand, using the fact that some fluids thermally contract on cooling, e.g., the argon liquid investigated here, reducing the temperature places the fluid in the liquid-vapor coexistence regime. If the bottom wall temperature is further reduced, the fluid will crystallize starting from the bottom surface, creating a "frozen" bubble in the crystallized state. It was found that the confining walls and not the quenching rate primarily affect the crystallization process. However, the fastest cooling rate investigated herein led to a decrease of the boiling initiation temperature. At a lower cooling rate, the vapor nucleation temperature was the same as the equilibrium boiling temperature for the confined liquid. Small temperatures in the confined system result in dominating attraction forces at the fluid-wall interface exposing the fluid to tensile stress. The increased influence of the walls results in a significant decrease of the boiling as well as freezing temperatures.

Solidification of gold nanoparticles in carbon nanotubes.

The structure and the solidification of gold nanoparticles in a carbon nanotube are investigated using molecular dynamics simulations. The simulations indicate that the predicted solidification temperature of the enclosed particle is lower than its bulk counterpart, but higher than that observed for clusters placed in vacuum. A comparison with a phenomenological model indicates that, in the considered range of tube radii (R(CNT)) of 0.5 < R(CNT) < 1.6 nm, the solidification temperature depends mainly on the length of the particle with a minor dependence on R(CNT).

Oscillatory behavior of nanodroplets.

Molecular dynamics (MD) simulations were performed in order to investigate the phenomenon of free oscillations of nanodroplets and the extent to which the continuum theory for such oscillations holds at nanoscales. The effect of temperature on these oscillations is also studied. The surface tension, a key property for the phenomenon of interest, was evaluated and compared with the experimental values of argon, showing that with an appropriate choice of the cutoff distance in the MD simulations, it is possible to predict the surface tension with good approximation. Nanoscale capillary waves on the free surface of the droplet were observed and compared to continuum theoretical predictions of the same. The nanodroplet interface thickness calculated based on continuum theory for these waves agreed well with the molecular dynamics calculation of the interface thickness. The frequencies of the oscillation of the droplet were calculated for all the studied temperatures and compared with the classical continuum theory. Although the simulated system cannot be considered strictly as a continuum, a good overall agreement was found.

[Smoking cessation course organized by the Italian League for the fight against tumors in Milan and Rome: determinants of cessation after the course and after a year]. / Il corso per smettere di fumare organizzato dalla Lega italiana per la lotta contro i tumori a Milano e Roma: determinanti della cessazione alla fine del corso e dopo un anno.

The Italian League against Cancer organizes a group behaviour therapy program for smoking cessation in Milan and Rome. Groups meet for 8-9 sessions; sessions are managed by a therapist. In the analized courses participants are 43-44 years on the average, with a middle/high level of education. They are heavy smokers with a high level of nicotine dependence and they greatly trust in the program. At the end of the program 67% of participants in Milan and 76% in Rome declare they no longer smoke. One year later, phone interviews show that 22% of participants in Milan and 25% in Rome are still non smokers. At the end of the program quitting-smoking predictors are: attendance at at least 6-7 sessions, smoking less than 30 cigarettes a day before the course and male gender; one year later attendance at at least 6-7 sessions, and scarce nicotine dependence (smoking less than 30 cigarettes a day before the program or a low score at the Fagerström Tolerance Questionnaire).

Evolution of repetitive proteins: spider silks from Nephila clavipes (Tetragnathidae) and Araneus bicentenarius (Araneidae).

Spider silks are highly repetitive proteins, characterized by regions of polyalanine and glycine-rich repeating units. We have obtained two variants of the Spidroin 1 (NCF-1) silk gene sequence from Nephila clavipes. One sequence (1726 bp) was from a cloned cDNA, and the other (1951 bp) was from PCR of genomic DNA. When these sequences are compared with each other and the previously published Spidroin 1 sequence, there are differences due to sequence rearrangements, as well as single base substitutions. These variations are similar to those that have been reported from other highly repetitive genes, and probably represent the results of unequal cross-overs. We have also obtained 708 bp of sequence from pCR of genomic DNA from Araneus biocentenarius. This sequence shows considerable similarity to a dragline sequence (ADF-3) from A. diadematus, as well as Spidroin 2 (NCF-2) from N. clavipes. Minor but consistent differences in the repeating unit sequence between A. bicentenarius and A. diadematus suggest that concerted evolution or gene conversion processes are acting to maintain similarity among repeat units within a single gene.

Purification and characterization of recombinant spider silk expressed in Escherichia coli.

A partial cDNA clone, from the 3' end of the dragline silk gene was isolated from Nephila clavipes major ampullate glands. This clone contains a 1.7-kb insert, consisting of a repetitive coding region of 1.4-kb and a 0.3-kb nonrepetitive coding region; 1.5-kb of the 1.7-kb fragment was cloned into Escherichia coli and a 43-kDa recombinant silk protein was expressed. Characterization of the purified protein by Western blot, amino acid composition analysis, and matrix-assisted laser desorption ionization/time-of-flight mass spectrometry confirms it to be spider dragline silk.

[Dynamic obstruction to left ventricular outflow during dobutamine stress echocardiography: the probable mechanisms and clinical implications]. / Ostruzione dinamica all'efflusso ventricolare sinistro durante ecocardiografia da stress con dobutamina: probabili meccanismi ed implicazioni cliniche.

We observed the development of left ventricular outflow tract dynamic obstruction in some patients during dobutamine stress echocardiography. The purpose of this study was to identify the possible mechanisms and to consider the clinical implications. From 11/04/94 to 01/09/97 we studied 547 patients; 42 patients developed dynamic obstruction, defined as a late peak Doppler velocity profile that exceeded baseline outflow velocity by at least 1 m/s. The encountered mechanisms were: increased myocardial contractility; systolic anterior motion of the mitral valve; decreased venous return to the left ventricle, and peculiar characteristics of the left ventricular geometry. The results of this study show that the dynamic obstruction is mainly due to the first mechanism and secondarily to some characteristics of the left ventricular geometry. The hypotension observed in a few cases is not related to the dynamic obstruction but to beta 2 receptor hypersensibility to dobutamine. The symptoms, like dyspnea and chest pain, experienced by these patients are related to the dynamic obstruction rather than to the presence of coronary artery disease. In conclusion, we think that patients who develop dynamic obstruction, without wall motion abnormalities, during dobutamine stress echocardiography, may behave pathophysiologically as patients with obstructive hypertrophic cardiomyopathy, in whom diastolic dysfunction and outflow tract obstruction are responsible for symptoms. Therefore, these patients require a pharmacological treatment with beta blockers and/or non-dihydropyridine calcium channel blockers.

[Vein patency in patients with pacemaker implanted via subclavian vein: digital phlebography assessment]. / Pervietà venosa nei pazienti con pacemaker impaintati per via succlavia: controlli con flebografia digitalizzata.

Venous thrombosis is a well-known complication of permanent cardiac pacemaker implantation, particularly, chronic occlusion of the subclavian vein is reported to occur in 20-33% of the cases where the percutaneous approach is performed. We examined 135 asymptomatic patients with digital venography to asses the frequency of venous thromboses causing stenosis and occlusion of the subclavian or anonymous arteries in pacemaker carriers. We considered both one- (44) and two-chamber (91) pacemakers and investigated a possible statistically significant difference between them: we found 21 venous thromboses (15%), seven of them in one-chamber pacemakers (15.9%) and 14 two-chambers pacemakers (15.3%). None of our 94 male and 41 female patients was on anticoagulants or had any evidence of coagulation disorders. Venography was performed 39.3 months (mean) after pacemaker implantation (range: 3-120 months). We conclude that digital venography is a simple and relatively noninvasive method permitting better depiction of subclavian, anonymous and caval veins than Doppler US and also showing some vascular abnormalities which may complicate pacemaker implantation.

Sequence conservation in the C-terminal region of spider silk proteins (Spidroin) from Nephila clavipes (Tetragnathidae) and Araneus bicentenarius (Araneidae).

The polymerase chain reaction (PCR) has been used to amplify the portion of the Spidroin 1 gene that codes for the C-terminal part of the silk protein of the spider Nephila clavipes. Along with some substitution mutations of minor consequence, the PCR-derived sequence reveals an additional base missing from the previously published Nephila Spidroin 1 sequence. Comparison of the PCR-derived sequence with the equivalent region of Spidroin 2 indicates that the insertion of this single base results in greatly increased similarity in the resulting amino acid sequences of Spidroin 1 and Spidroin 2 (75% over 97 amino acids). The same PCR primers also amplified a fragment of the same length from Araneus bicentenarius. This sequence is also very similar to Spidroin 1 of Nephila (71% over 238 bases excluding the PCR primers, which translates into 76% over 79 amino acids).

Molecular weight distribution of chitosan isolated from Mucor rouxii under different culture and processing conditions.

The isolation of chitosan from a fungal source offers the potential of a product with controlled physicochemical properties not obtainable by the commercial chemical conversion of crustacean chitin. A variety of culture and processing protocols using Mucor rouxii were studied for their effects on biomass yield and chitosan molecular weight. Weight-averaged molecular weight determined by gel permeation chromotography ranged from 2.0 x 10(5) to approximately 1.4 x 10(6) daltons. The chitosan yield ranged from 5% to 10% of total biomass dry weight and from 30% to 40% of the cell wall. Of the culture parameters studied, length of incubation and medium composition effected biomass production and molecular weight. Modification of the processing protocol, including the type and strength of acid, and cell wall disruption in acid prior to refluxing were used to optimize the efficiency of chitosan extraction.The degree of deacetylation of fungal and commercial chitosans was compared using infrared spectrometry, titration, and first derivative of UV absorbance spectrometry. The chitosan obtained directly from the fungal cell wall had a higher degree of deacetylation than commercial chitosan from the chemical conversion process.

Continuous culture system for production of biopolymer levan using erwinia herbicola.

The optimal production of the fructan biopolymer levan by the bacterium Erwinia herbicola was investigated, including variations in nitrogen, carbon and phosphorous sources, pH, incubation time, culture yields up to 19% by weight produced based on conversion of sucrose as the carbon source when grown in a continuous culture system and processed by tangential flow filtration. Product identity was confirmed with gas chromatography (GC) and (13)C nuclear magnetic resonance (NMR). Gel permeation chromatography (GPC) and low-angle laser light scattering (LALLS) determination of the molecular weight of the product showed a significant difference in molecular weight values dependent on the method of analysis. Analysis by GPC resulted in molecular weight one order of magnitude lower than LALLS independent of sample, underscoring the unusual nature of this biopolymer.