bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Surface Photo Charge Effect for Milk Quality Control
Authors: Ivanov O. , Radanski S.
Published: August 2009

ABSTRACT:  The potential difference induced by the interaction of samples with electromagnetic radiation in the visible region is used for food characterization. In this article we show that the above effect can be applied for the understanding of specific reactions and processes taking place in milk such as change of the acidity and changes caused by an added reagent. We also propose a technique for instantaneous detection of inhibitors of starter bacteria in milk. We suggest possible methods for quality control of milk and other foods. Instantaneous results, practically no expenses for consumables, and possibilities for field measurements will be some of the advantages of this approach.
Antistaphylococcal Effect of Enterocin AS‐48 in Bakery Ingredients of Vegetable Origin, Alone and in Combination with Selected Antimicrobials
Authors: Viedma Pilar Martinez , Abriouel Hikmate , Omar Nabil Ben , López Rosario Lucas , Gálvez Antonio
Published: August 2009

ABSTRACT:  The inhibitory effect of enterocin AS‐48 against Staphylococcus aureus was investigated in various types of bakery ingredients. Antibacterial activity greatly depended on the food substrate, ranging from complete inactivation of S. aureus in liquid caramel (in which the bacterium survived poorly) to no significant inhibition (as in vanilla or chocolate creams). Significant reductions of viable counts in the range of 1.8 to 2.7 log units (P < 0.05) were achieved in substrates like pumpkin confiture or diluted almond cream stored at temperatures of 10 or 22 °C. Given the very low activity detected in chocolate substrates, enterocin AS‐48 was tested in combination with other antimicrobials. Bactericidal activity increased markedly for the combinations of AS‐48 and 0.1% eugenol (v/v), 0.5% 2‐nitropropanol (v/v), or 3% Nisaplin (w/v). Enterocin AS‐48 could be applied in combination with other antimicrobials for preservation of bakery ingredients against S. aureus.
Antibacterial Effects of Allspice, Garlic, and Oregano Essential Oils in Tomato Films Determined by Overlay and Vapor‐Phase Methods
Authors: Du W‐X. , Olsen C.W. , Avena‐Bustillos R.J. , McHugh T.H. , Levin C.E. , Mandrell R. , Friedman Mendel
Published: August 2009

ABSTRACT:  Physical properties as well as antimicrobial activities against Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes of allspice, garlic, and oregano essential oils (EOs) in tomato puree film‐forming solutions (TPFFS) formulated into edible films at 0.5% to 3% (w/w) concentrations were investigated in this study. Antimicrobial activities were determined by 2 independent methods: overlay of the film on top of the bacteria and vapor‐phase diffusion of the antimicrobial from the film to the bacteria. The results indicate that the antimicrobial activities against the 3 pathogens were in the following order: oregano oil > allspice oil > garlic oil. Listeria monocytogenes was less resistant to EO vapors, while E. coli O157:H7 was more resistant to EOs as determined by both overlay and vapor‐phase diffusion tests. The presence of plant EO antimicrobials reduced the viscosity of TPFFS at the higher shear rates, but did not affect water vapor permeability of films. EOs increased elongation and darkened the color of films. The results of the present study show that the 3 plant‐derived EOs can be used to prepare tomato‐based antimicrobial edible films with good physical properties for food applications by both direct contact and indirectly by vapors emanating from the films.
Safety and Functional Aspects of Preselected Enterococci for Probiotic Use in Iberian Dry‐Fermented Sausages
Authors: Ruiz‐Moyano Santiago , Martín Alberto , Benito María José , Aranda Emilio , Casquete Rocío , Córdoba María de Guía
Published: August 2009

ABSTRACT:  The purpose of this study was to investigate enterococci for potential probiotic use in Iberian dry‐fermented sausages. A total of 15 strains isolated from Iberian dry‐fermented sausages, human feces, and pig feces were evaluated for their safety and functional characteristics including biogenic amine (BA) production, antibiotic susceptibility, hemolysis, virulence determinants, cell adhesion, and antimicrobial activity against foodborne pathogens. The strain Enterococcus faecium SE906 was able to establish itself on the intestinal epithelium, inhibiting such pathogenic bacteria as Listeria monocytogenes in vitro. This strain was also considered safe to be used for its low aminogenic potential, and its antibiotic resistance pattern and virulence determinants, being identified as a potential probiotic meat starter culture suitable for manufacture of dry‐fermented Iberian sausages.
Chemical Composition and In Vitro Polysaccharide Fermentation of Different Beans (Phaseolus vulgaris L.)
Authors: Campos‐Vega R. , Reynoso‐Camacho R. , Pedraza‐Aboytes G. , Acosta‐Gallegos J.A. , Guzman‐Maldonado S.H. , Paredes‐Lopez O. , Oomah B.D. , Loarca‐Piña G.
Published: August 2009

ABSTRACT:  The composition of bioactives including polysaccharide yield and resistant starch (RS) content of 4 raw and cooked bean (Phaseolus vulgaris L.) cultivars was evaluated. Polysaccharide was fermented in vitro by incubation with human gut flora under anaerobic conditions and short‐chain fatty acids (SCFAs) production was compared at 6, 12, and 24 h by gas chromatography. Polysaccharide and soluble fiber contents increased upon cooking with stachyose as the major oligosaccharide. Cooked bean of cultivar Bayo Madero had the highest yield of polysaccharides (55%) and resistant starch (37%), followed by those of Negro 8025 (48% and 32%, respectively). Acetate was the most abundant SCFAs formed in all bean varieties. The concentration of SCFAs was cultivar‐dependent; Bayo Madero and Negro 8025 displayed the highest concentration of butyrate (15 mmol/L), while Azufrado Higuera had the lowest and highest concentrations of acetate (39 mmol/L) and propionate (14 mmol/L), respectively. The results suggest that the common bean is an excellent source of polysaccharides that can be fermented in the colon and produce SCFAs, compounds previously reported to exert health benefits.
Inactivation of Bacillus atrophaeus Spores with Surface‐Active Peracids and Characterization of Formed Free Radicals Using Electron Spin Resonance Spectroscopy
Authors: Mohan Anand , Dunn Joseph , Hunt Melvin C. , Sizer Charles E.
Published: August 2009

ABSTRACT:  This study investigated microbial inactivation via surface‐active peracids and used electron spin resonance spectroscopy to characterize the active components and free radical formation. Bacillus atrophaeus spores were injected directly into 3 different concentrations of the peracid disinfectant (1.1%, 1.3%, or 1.5%) for various times (5, 10, 15, or 20 s) at 3 different temperatures (50, 60, or 70 °C) to evaluate the sporicidal activity of the disinfectant mixture. Spectroscopy revealed that the combination of hydrogen peroxide, peracetic acid, and octanoic acid were highly effective at forming a complex mixture of sporicidal, free radical intermediates including hydroxyl and superoxide radicals. Individual components of this mixture alone were not as effective as the final combination. This information has practical applications in the food industry for design of effective sanitation and disinfection agents and suggests that kinetic models could be developed to account for both the physical removal and localized inactivation of spores on food‐contact surfaces.
Microarray analysis yields candidate markers for rotation resistance in the western corn rootworm beetle, Diabrotica virgifera virgifera
Authors: Knolhoff Lisa M. , Walden Kimberly K. O. , Ratcliffe Susan T. , Onstad David W. , Robertson Hugh M.
Published: August 2009

As pest species may evolve resistance to chemical controls, they may also evolve resistance to cultural control methods. Yearly rotation of corn (Zea mays) with another crop interrupts the life cycle of the western corn rootworm beetle (Diabrotica virgifera virgifera, Coleoptera: Chrysomelidae), but behavioral resistance to crop rotation is now a major problem in the Midwest of the USA. Resistant adult females exhibit reduced fidelity to corn as a host and lay their eggs in the soil of both corn and soybean (Glycine max) fields. Behavioral assays suggest that the adaptation is related to increased locomotor activity, but finding molecular markers has been difficult. We used microarray analysis to search for gene expression differences between resistant and wild‐type beetles. Candidates validated with real‐time polymerase chain reaction exhibit predicted patterns from the microarray in independent samples across time and space. Many genes more highly expressed in the rotation‐resistant females have no matches to known proteins, and most genes that were more lowly expressed are involved in antimicrobial defense.
Quantification and reduction of bias from sampling larvae to infer population and landscape genetic structure
Authors: GOLDBERG CAREN S. , WAITS LISETTE P.
Published: August 2009

A well‐designed sampling scheme is critical for obtaining accurate results from population genetic studies. Larval samples contain only the genetic material of successful breeders, often of a single year, and may be biased towards particular families. To quantify the bias of using larval samples to infer population and landscape genetic structure and explore how this bias may be reduced using sibship analysis, we analysed eight microsatellite loci from 484 tissue samples of larvae and adults of Columbia spotted frogs (Rana luteiventris) and long‐toed salamanders (Ambystoma macrodactylum) at nine breeding sites in north Idaho. Differences in allele frequencies between adult and larval samples were not detected after full‐siblings were removed from the larval data set for Columbia spotted frogs; for long‐toed salamanders, these differences remained at two out of four ponds. Data from Columbia spotted frog larvae indicated higher levels of differentiation among populations (median difference in FST = 0.020, P < 0.01), as predicted by population genetic theory, whereas data from larval samples of long‐toed salamanders showed some evidence of lower levels of differentiation among populations (median difference in FST = 0.012, P = 0.06). For both species, removing all but one individual from each full‐sibling family led to parameter estimates that were closer to those calculated from adult samples for both population and landscape genetic measures. Removal of full‐siblings is likely to improve estimates of population genetic parameters; however, knowledge of the species’ breeding system is essential for understanding additional sources of bias when inferring population genetic structure from larval samples.
A multiplex PCR assay to distinguish among three sympatric marsupial taxa from Huon Peninsula, Papua New Guinea, using the mitochondrial control region
Authors: McGREEVY T. J. , DABEK L. , HUSBAND T. P.
Published: August 2009

Matschie’s tree kangaroo (Dendrolagus matschiei) is an endangered arboreal macropodid marsupial that is difficult to locate in the wild. The Tree Kangaroo Conservation Program noninvasively collected D. matschiei faecal samples, but a high percentage of samples were misidentified and belonged to two terrestrial macropods, New Guinea pademelon (Thylogale browni) and small dorcopsis (Dorcopsulus vanheurni). We developed species‐specific primers that produced a unique sized mitochondrial DNA control region gene product for each taxon and achieved an 89% correct assignment rate. The species‐specific primers can increase the accuracy of D. matschiei density estimates and facilitate additional genetic analyses of wild D. matschiei.
Human motor associative plasticity induced by paired bihemispheric stimulation
Authors: Koganemaru Satoko , Mima Tatsuya , Nakatsuka Masahiro , Ueki Yoshino , Fukuyama Hidenao , Domen Kazuhisa
Published: August 2009

Paired associative stimulation (PAS) is an effective non‐invasive method to induce human motor plasticity by the repetitive pairing of peripheral nerve stimulation and transcranial magnetic stimulation (TMS) at the primary motor cortex (M1) with a specific time interval. Although the repetitive pairing of two types of afferent stimulation might be a biological basis of neural plasticity and memory, other types of paired stimulation of the human brain have rarely been studied. We hypothesized that the repetitive pairing of TMS and interhemispheric cortico‐cortical projection or paired bihemispheric stimulation (PBS), in which the right and left M1 were serially stimulated with a time interval of 15 ms, would produce an associative long‐term potentiation (LTP)‐like effect. In this study, 23 right‐handed healthy volunteers were subjected to a 0.1 Hz repetition of 180 pairings of bihemispheric TMS, and physiological and behavioural measures of the motor system were compared before, immediately after, 20 min after and 40 min after PBS intervention. The amplitude of the motor evoked potential (MEP) induced by the left M1 stimulation and its input–output function increased for up to ∼20 min post‐PBS. Fine finger movements were also facilitated by PBS. Spinal excitability measured by the H‐reflex was insensitive to PBS, suggesting a cortical mechanism. The associative LTP‐like effect induced by PBS was timing dependent, occurring only when the interstimulus interval was 5–25 ms. These findings demonstrate that using PBS in PAS can induce motor cortical plasticity, and this approach might be applicable to the rehabilitation of patients with motor disorders.
Expression of anoctamin 1/TMEM16A by interstitial cells of Cajal is fundamental for slow wave activity in gastrointestinal muscles
Authors: Hwang Sung Jin , Blair Peter J. A. , Britton Fiona C. , O’Driscoll Kate E. , Hennig Grant , Bayguinov Yulia R. , Rock Jason R. , Harfe Brian D. , Sanders Kenton M. , Ward Sean M.
Published: August 2009

Interstitial cells of Cajal (ICC) generate pacemaker activity (slow waves) in gastrointestinal (GI) smooth muscles, but the mechanism(s) of pacemaker activity are controversial. Several conductances, such as Ca2+‐activated Cl− channels (CaCC) and non‐selective cation channels (NSCC) have been suggested to be involved in slow wave depolarization. We investigated the expression and function of a new class of CaCC, anoctamin 1 (ANO1), encoded by Tmem16a, which was discovered to be highly expressed in ICC in a microarray screen. GI muscles express splice variants of the Tmem16a transcript in addition to other paralogues of the Tmem16a family. ANO1 protein is expressed abundantly and specifically in ICC in all regions of the murine, non‐human primate (Macaca fascicularis) and human GI tracts. CaCC blocking drugs, niflumic acid and 4,4′‐diisothiocyano‐2,2′‐stillbene‐disulfonic acid (DIDS) reduced the frequency and blocked slow waves in murine, primate, human small intestine and stomach in a concentration‐dependent manner. Unitary potentials, small stochastic membrane depolarizations thought to underlie slow waves, were insensitive to CaCC blockers. Slow waves failed to develop by birth in mice homozygous for a null allele of Tmem16a (Tmem16atm1Bdh/tm1Bdh) and did not develop subsequent to birth in organ culture, as in wildtype and heterozygous muscles. Loss of function of ANO1 did not inhibit the development of ICC networks that appeared structurally normal as indicated by Kit antibodies. These data demonstrate the fundamental role of ANO1 in the generation of slow waves in GI ICC.
Memantine binding to a superficial site on NMDA receptors contributes to partial trapping
Authors: Kotermanski Shawn E. , Wood Jesse T. , Johnson Jon W.
Published: August 2009

Although many nervous system disorders are associated withN‐methyl‐d‐aspartate (NMDA) receptor overactivation, pharmacological inhibition of NMDA receptors has typically demonstrated limited clinical value due to debilitating psychotomimetic side‐effects. Memantine, however, induces far fewer behavioural side‐effects than other NMDA receptor channel blockers such as ketamine, and slows the progressive cognitive decline associated with Alzheimer's disease. Memantine and ketamine inhibit NMDA receptors with similar affinity and kinetics. A prominent mechanistic difference between memantine and ketamine is the degree to which they are ‘trapped’ within the closed channel of NMDA receptors following removal of agonist: ketamine becomes trapped in nearly all NMDA receptors to which it was bound before agonist removal, whereas some bound memantine molecules dissociate after agonist removal, a phenomenon called partial trapping. Here we investigated the mechanism underlying partial trapping of memantine by recombinant NR1/2A NMDA receptors. We found that memantine dissociation from NR1/2A receptors after agonist removal (the process that results in partial trapping) followed an exponential time course with τ= 0.79 ± 0.32 s. Neither membrane voltage depolarization nor maintained presence of memantine after agonist removal affected partial trapping, suggesting that partial trapping does not result from memantine escape through open channels. We tested the hypothesis that partial trapping results from binding of memantine to two sites, a superficial ‘non‐trapping’ site and a deep ‘trapping’ site, which cannot be occupied simultaneously. This hypothesis was supported by the lack of ketamine binding to the superficial site, the voltage dependence of partial trapping, and the effect on partial trapping of a mutation near the deep site. The superficial binding site for memantine may, by causing partial trapping, contribute to memantine's unique therapeutic utility.
Membrane oestrogen receptor α signalling to cell functions
Authors: Levin Ellis R.
Published: August 2009

Conservation of steroid hormone action outside the nucleus occurs from plants that make brassinosteroids to higher metazoans (primates). In plants, steroid hormone action occurs when the brassinosteroids bind a membrane tyrosine kinase receptor. Ligated receptors for all sex steroids exist at the plasma membrane and rapidly signal through G proteins to second messengers including calcium, cAMP and cGMP, activating proximal and more distal kinases. These signal cascades impact many functions of steroid hormones, responsible for the biological actions of these molecules. Support also exists for membrane‐localized receptors of other members of the steroid superfamily, responding to glucocorticoids, mineralocorticoids, thyroid hormone, and vitamin D. The nature of these receptors is in some cases unclear. Steroid receptors also exist in discrete cytoplasmic organelles, most notably the mitochondria, although the functions of these receptors are poorly understood. In this review, I highlight the essential elements of the membrane oestrogen receptor α, noting where conserved aspects exist for other steroid receptors.
The role of oestrogens in the adaptation of islets to insulin resistance
Authors: Nadal Angel , Alonso‐Magdalena Paloma , Soriano Sergi , Ropero Ana B. , Quesada Ivan
Published: August 2009

Pregnancy is characterized by peripheral insulin resistance, which is developed in parallel with a plasma increase of maternal hormones; these include prolactin, placental lactogens, progesterone and oestradiol among others. Maternal insulin resistance is counteracted by the adaptation of the islets of Langerhans to the higher insulin demand. If this adjustment is not produced, gestational diabetes may be developed. The adaptation process of islets is characterized by an increase of insulin biosynthesis, an enhanced glucose‐stimulated insulin secretion (GSIS) and an increase of β–cell mass. It is not completely understood why, in some individuals, β–cell mass and function fail to adapt to the metabolic demands of pregnancy, yet a disruption of the β–cell response to maternal hormones may play a key part. The role of the maternal hormone 17β‐oestradiol (E2) in this adaptation process has been largely unknown. However, in recent years, it has been demonstrated that E2 acts directly on β–cells to increase insulin biosynthesis and to enhance GSIS through different molecular mechanisms. E2 does not increase β–cell proliferation but it is involved in β–cell survival. Classical oestrogen receptors ERα and ERβ, as well as the G protein‐coupled oestrogen receptor (GPER) seem to be involved in these adaptation changes. In addition, as the main production of E2 in post‐menopausal women comes from the adipose tissue, E2 may act as a messenger between adipocytes and islets in obesity.
Rapid actions of oestrogen on gonadotropin‐releasing hormone neurons; from fantasy to physiology?
Authors: Herbison Allan E.
Published: August 2009

Oestradiol (E2) exerts critical homeostatic feedback effects upon gonadotropin‐releasing hormone (GnRH) neurons to maintain fertility. In the female, E2 has both negative and positive feedback actions to suppress and stimulate GnRH neuron activity at different times of the ovarian cycle. This review summarizes reported rapid E2 effects on native embryonic and adult GnRH neurons and attempts to put them into a physiological perspective. Oestrogen has been shown to rapidly modulate multiple processes in embryonic and adult GnRH neurons including intracellular calcium levels, electrical activity and specific second messenger pathways, as well as GnRH secretion itself. Evaluation of in vivo data suggests that there is no essential role for rapid E2 actions in the positive feedback mechanism but that they may comprise part of the negative feedback pathway. Adult GnRH neurons are only likely to be exposed to E2 from the gonads via the circulation with appropriate physiological E2 concentrations in the rodent being 10–50 pm for negative feedback ranging up to 400 pm for positive feedback. Although most studies to date have examined the effects of supraphysiological E2 levels on GnRH neurons, there is accumulating evidence that rapid E2 actions may have a physiological role in suppressing GnRH neuron activity.
Flow Characteristics in a Curved Rectangular Channel With Variable Cross-Sectional Area
Authors: Bhunia Avijit , Chen C. L.
Published: August 2009

Laminar air flow through a curved rectangular channel with a variable cross-sectional (c/s) area (diverging-converging channel) is computationally investigated. Such a flow passage is formed between the two fin walls of a 90 deg bend curved fin heat sink, used in avionics cooling. Simulations are carried out for two different configurations: (a) a curved channel with long, straight, constant c/s area inlet and outlet sections (entry and exit lengths); and (b) a short, curved channel with no entry and exit lengths. Formation of a complex 3D flow pattern and its evolution in space is studied through numerical flow visualization. Results show that a secondary motion sets in the radial direction of the curved section, which in combination with the axial (bulk) flow leads to the formation of a base vortex. In addition, under certain circumstances the axial and secondary flow separate from multiple locations on the channel walls, creating Dean vortices and separation bubbles. Velocity above which the Dean vortices appear is cast in dimensionless form as the critical Dean number, which is calculated to be 129. Investigation of the friction factor reveals that pressure drop in the channel is governed by both the curvature effect as well as the area expansion effect. For a short curved channel where area expansion effect dominates, pressure drop for developing flow can be even less than that of a straight channel. A comparison with the flow in a constant c/s area, curved channel shows that the variable c/s area channel geometry leads to a lower critical Dean number and friction factor.
Large-Eddy Simulation of Wake and Boundary Layer Interactions Behind a Circular Cylinder
Authors: Sarkar S. , Sarkar Sudipto
Published: August 2009

Large-eddy simulations (LESs) of flow past a circular cylinder in the vicinity of a flat plate have been carried out for three different gap-to-diameter (G/D) ratios of 0.25, 0.5, and 1.0 (where G signifies the gap between the flat plate and the cylinder, and D signifies the cylinder diameter) following the experiment of Price et al. (2002, “Flow Visualization Around a Circular Cylinder Near to a Plane Wall,” J. Fluids Struct., 16, pp. 175–191). The flow visualization along with turbulent statistics are presented for a Reynolds number of Re=1440 (based on D and the inlet free-stream velocity U∞). The three-dimensional time-dependent, incompressible Navier–Stokes equations are solved using a symmetry-preserving finite-difference scheme of second-order spatial and temporal accuracy. The immersed-boundary method is employed to impose the no-slip boundary condition at the cylinder surface. An attempt is made to understand the physics of flow involving interactions of shear layers shed from the cylinder and the wall boundary layer. Present LES reveals the shear layer instability and formation of small-scale eddies apart from their mutual interactions with the boundary layer. It has been observed that G/D ratio has a large influence on the modification of wake dynamics and evolution of the wall boundary layer. For a low gap ratio, it is difficult to identify the boundary layer because of its strong interactions with the shear layers; however, a rapid transition to turbulence of the boundary layer, which is similar to bypass transition, is observed for a large gap ratio.
Analytical Solution for Newtonian Laminar Flow Through the Concave and Convex Ducts
Authors: Firouzi M. , Hashemabadi S. H.
Published: August 2009

In this paper, the motion equation for steady state, laminar, fully developed flow of Newtonian fluid through the concave and convex ducts has been solved both numerically and analytically. These cross sections can be formed due to the sedimentation of heavy components such as sand, wax, debris, and corrosion products in pipe flows. The influence of duct cross section on dimensionless velocity profile, dimensionless pressure drop, and friction factor has been reported. Finally based on the analytical solutions three new correlations have been proposed for the product of Reynolds number and Fanning friction factor (Cf Re) for these geometries.
Pharyngeal Airflow Analysis in Obstructive Sleep Apnea Patients Pre- and Post-Maxillomandibular Advancement Surgery
Authors: Huynh John , Kim Ki Beom , McQuilling Mark
Published: August 2009

The purpose of this study was to evaluate pharyngeal airflow in obstructive sleep apnea (OSA) patients following maxillomandibular advancement (MMA) surgery using computational fluid dynamics (CFD). Computerized models of four OSA patients, pre- and postsurgery, were created using cone beam computed tomography scans. CFD was used to model airflow at inspiration rates of 340 ml/s, 400 ml/s, and 460 ml/s. The relative pressure, eddy viscosity coefficient, and total area-averaged pressure drops were selected for comparison. Results show a decrease in airway resistance of over 90% for three out of four patients. In these three patients, the MMA surgery reduced the constriction along the airway, which resulted in reduced drag and therefore reduced pressure drop required to move a constant volumetric flow between pre- and postsurgery models. CFD analyses on airways of OSA patients provide data that suggest an improvement in airflow following MMA surgery with less effort required for maintaining constant flow.
Measurements of a Wall Jet Impinging Onto a Forward Facing Step
Authors: Langer D. C. , Fleck B. A. , Wilson D. J.
Published: August 2009

This study examines a horizontal wall jet impinging onto a forward facing vertical step in a cross-flow. Planar laser induced fluorescence (PLIF) experiments in a 68×40 mm2 water channel indicate how the wall-jet flow after impinging onto the step becomes a vertical jet with an elliptical cross section. This study proposes predictive empirical correlations for the aspect ratio and perimeter of the jet’s elliptical cross section based on the step geometry and the inlet flow conditions. A numerical model is also presented, which was produced from a commercial Reynolds averaged Navier–Stokes computational fluid dynamics (CFD) code with the k-ϵ closure model. The experimental results were well represented by correlations for the perimeter P and aspect ratio S using the parameters H (the step height), L∘ (the distance from the jet represented as a point source to the step), and R (the velocity ratio). The CFD simulation was able to predict the trends in the perimeter (under different conditions), aspect ratio, and the shape of the concentration profile, but overpredicted the jet’s perimeter by approximately 50%. The results of these tests are required as input parameters when modeling jet trajectories.
Curved Non-Newtonian Liquid Jets With Surfactants
Authors: Uddin Jamal , Decent Stephen P.
Published: August 2009

Applications of the breakup of a liquid jet into droplets are common in a variety of different industrial and engineering processes. One such process is industrial prilling, where small spherical pellets and beads are generated from the rupture of a liquid thread. In such a process, curved liquid jets produced by rotating a perforated cylindrical drum are utilized to control drop sizes and breakup lengths. In general, smaller droplets are observed as the rotation rate is increased. The addition of surfactants along the free surface of the liquid jet as it emerges from the orifice provides a possibility of further manipulating breakup lengths and droplet sizes. In this paper, we build on the work of Uddin et al. (2006, “The Instability of Shear Thinning and Shear Thickening Liquid Jets: Linear Theory,” ASME J. Fluids Eng., 128, pp. 968–975) and investigate the instability of a rotating liquid jet (having a power law rheology) with a layer of surfactants along its free surface. Using a long wavelength approximation we reduce the governing equations into a set of one-dimensional equations. We use an asymptotic theory to find steady solutions and then carry out a linear instability analysis on these solutions.
On the Pulsed and Transitional Behavior of an Electrified Fluid Interface
Authors: Chiarot Paul R. , Gubarenko Sergey I. , Ben Mrad Ridha , Sullivan Pierre E.
Published: August 2009

Transient modes of an electrified fluid interface are investigated, specifically, (a) intermittent or pulsed cone-jet mode and (b) smooth and abrupt transitions of the interface in response to a step voltage. These modes were studied experimentally by capturing the motion of the interface and measuring the emitted ion current (via electrospray) as they occur. The observed phenomena are described using an analytical model for the equilibrium of an electrified fluid interface, and the effect of operational parameters on the transient modes is discussed. Pressure, which is related to the supplied flow rate, significantly influences the behavior of the transient modes. It is useful to understand transient modes so they can be avoided in applications that require a stable electrospray. However, with improved knowledge, the modes studied here can assist in the development of specialized applications.
Circulation Generation and Vortex Ring Formation by Conic Nozzles
Authors: Rosenfeld Moshe , Katija Kakani , Dabiri John O.
Published: August 2009

Vortex rings are one of the fundamental flow structures in nature. In this paper, the generation of circulation and vortex rings by a vortex generator with a static converging conic nozzle exit is studied numerically. Conic nozzles can manipulate circulation and other flow invariants by accelerating the flow, increasing the Reynolds number, and by establishing a two-dimensional flow at the exit. The increase in the circulation efflux is accompanied by an increase in the vortex circulation. A novel normalization method is suggested to differentiate between two contributions to the circulation generation: a one-dimensional slug-type flow contribution and an inherently two-dimensional flow contribution. The one-dimensional contribution to the circulation increases with the square of the centerline exit velocity, while the two-dimensional contribution increases linearly with the decrease in the exit diameter. The two-dimensional flow contribution to the circulation production is not limited to the impulsive initiation of the flow only (as in straight tube vortex generators), but it persists during the entire ejection. The two-dimensional contribution can reach as much as 44% of the total circulation (in the case of an orifice). The present study offers evidences on the importance of the vortex generator geometry, and in particular, the exit configuration on the emerging flow, circulation generation, and vortex ring formation. It is shown that both total and vortex ring circulations can be controlled to some extent by the shape of the exit nozzle.
Scattering of neutral hydrogen at energies less than 1 keV from tungsten and diamondlike carbon surfaces
Authors: Hughes Patrick P. , Coplan Michael A. , DeFazio Jeffery N. , Chornay Dennis J. , Collier Michael R. , Ogilvie Keith W. , Shappirio Mark D.
Published: August 2009

Neutral atom to negative ion conversion efficiencies were studied for polished tungsten and diamondlike carbon surfaces using a beam of incident hydrogen atoms. Neutral atoms at energies below 1 keV were scattered from the surfaces using incident angles between 6° and 20° measured from the surface plane. The angular and energy distributions of negative ions backscattering from the surfaces were measured and used to calculate the fraction of the incident beam that was converted to negative ions. The highest number and the lowest overall energy loss of backscattered ions were both observed near the specular reflection angle of the incident beam for the two surface materials studied. The total conversion efficiency was calculated to be near 2% for the tungsten and diamondlike carbon surfaces. Measurements taken while the surfaces were heated show a significant reduction in conversion efficiency, which is credited to the removal of adsorbates from the top layers of the surfaces.
Fluoroquinolone Resistance in
Mycobacterium tuberculosis
and Mutations in
gyrA
and
gyrB
Authors: Von Groll Andrea , Martin Anandi , Jureen Pontus , Hoffner Sven , Vandamme Peter , Portaels Françoise , Palomino Juan Carlos , da Silva Pedro Almeida
Published: August 2009

This study evaluated cross-resistance of
Mycobacterium tuberculosis
strains to ofloxacin, moxifloxacin, and gatifloxacin and investigated the presence of mutations in
gyrA
and
gyrB
. Fluoroquinolone susceptibilities were determined for 41
M. tuberculosis
strains by the proportion method on 7H11, and MICs were determined by the resazurin microtiter assay. Forty strains shared the same resistance results for the three fluoroquinolones. However, one strain, with an Asn-533 → Thr mutation in
gyrB
, was susceptible to ofloxacin but resistant to moxifloxacin and gatifloxacin.
Influence of Antidrug Antibodies on Plectasin Efficacy and Pharmacokinetics
Authors: Brinch Karoline Sidelmann , Frimodt-Møller Niels , Høiby Niels , Kristensen Hans-Henrik
Published: August 2009

Plectasin is a 4.4-kDa antimicrobial peptide with the potential to be a treatment of infections caused by gram-positive bacteria. Since plectasin is a large molecule compared to conventional antibiotics, the development of antidrug antibodies (ADAs) could be anticipated. The immunogenic properties of plectasin were assessed through immunization studies. In mice treated for 5 days with one to two daily subcutaneous doses of plectasin, no antibody response was observed. If the animals were immunized again, after a rest period, low levels of antibodies developed in approximately half the animals. Additionally, mice were immunized with plectasin in Freund's incomplete adjuvant (FIA). Ninety-two percent of these mice developed ADAs after repeated immunizations, with two-thirds having high levels of antibodies. An agar diffusion bioassay showed that sera from animals immunized with plectasin did not inhibit the efficacy of the drug, while hyperimmune sera from animals in which an immune response was provoked by immunization with plectasin in FIA reduced the efficacy of plectasin at the lowest concentration tested. Studies in the murine peritonitis model showed an excellent efficacy of plectasin for the treatment of
Streptococcus pneumoniae
infections both in naïve animals and in animals with ADAs. No difference in bacterial counts was seen when the animals were treated with plectasin at 2.5 mg/kg of body weight, a dose below the expected therapeutic level. When animals were treated with plectasin at 0.625 mg/kg, the effect was reduced but not neutralized in animals with high levels of ADAs. No animals showed signs of hypersensitivity or injection site reactions toward plectasin, and the half-life of the compound did not vary between animals with and without antibodies.
Horizontal Transfer of Tetracycline Resistance among
Chlamydia
spp. In Vitro
Authors: Suchland R. J. , Sandoz K. M. , Jeffrey B. M. , Stamm W. E. , Rockey D. D.
Published: August 2009

There are no examples of stable tetracycline resistance in clinical strains of
Chlamydia trachomatis
. However, the swine pathogen
Chlamydia suis
is commonly tetracycline resistant, both in America and in Europe. In tested U.S. strains, this resistance is mediated by a genomic island carrying a
tet
(C) allele. In the present study, the ability of
C. suis
to mobilize
tet
(C) into other chlamydial species was examined. Differently antibiotic resistant strains of
C. suis
,
C. trachomatis
, and
Chlamydia muridarum
were used in coculture experiments to select for multiply antibiotic resistant progeny. Coinfection of mammalian cells with a naturally occurring tetracycline-resistant strain of
C. suis
and a
C. muridarum
or
C. trachomatis
strain containing selected mutations encoding rifampin (rifampicin) or ofloxacin resistance readily produced doubly resistant recombinant clones that demonstrated the acquisition of tetracycline resistance. The resistance phenotype in the progeny from a
C. trachomatis
L2/ofl
R
-
C. suis
R19/tet
R
cross resulted from integration of a 40-kb fragment into a single ribosomal operon of a recipient, leading to a merodiploid structure containing three rRNA operons. In contrast, a cross between
C. suis
R19/tet
R
and
C. muridarum
MoPn/ofl
R
led to a classical double-crossover event transferring 99 kb of DNA from
C. suis
R19/tet
R
into
C. muridarum
MoPn/ofl
R
. Tetracycline resistance was also transferred to recent clinical strains of
C. trachomatis
. Successful crosses were not obtained when a rifampin-resistant
Chlamydophila caviae
strain was used as a recipient for crosses with
C. suis
or
C. trachomatis
. These findings provide a platform for further exploration of the biology of horizontal gene transfer in
Chlamydia
while bringing to light potential public health concerns generated by the possibility of acquisition of tetracycline resistance by human chlamydial pathogens.
Complete Nucleotide Sequences of Plasmids pEK204, pEK499, and pEK516, Encoding CTX-M Enzymes in Three Major
Escherichia coli
Lineages from the United Kingdom, All Belonging to the International O25:H4-ST131 Clone
Authors: Woodford Neil , Carattoli Alessandra , Karisik Edi , Underwood Anthony , Ellington Matthew J. , Livermore David M.
Published: August 2009

We determined the complete nucleotide sequences of three plasmids that encode CTX-M extended-spectrum β-lactamases (ESBLs) in pulsed-field gel electrophoresis-defined United Kingdom variants (strains A, C, and D) of the internationally prevalent
Escherichia coli
O25:H4-ST131 clone. Plasmid pEK499 (strain A; 117,536 bp) was a fusion of type FII and FIA replicons and harbored the following 10 antibiotic resistance genes conferring resistance to eight antibiotic classes:
bla
CTX-M-15
,
bla
OXA-1
,
bla
TEM-1,
aac6′-Ib-cr
,
mph
(A),
catB4
,
tet
(A), and the integron-borne
dfrA7
,
aadA5
, and
sulI
genes. pEK516 (strain D; 64,471 bp) belonged to incompatibility group IncFII and carried seven antibiotic resistance genes:
bla
CTX-M-15
,
bla
OXA-1
,
bla
TEM-1
,
aac6′-Ib-cr
,
catB4
, and
tet
(A), all as in pEK499. It also carried
aac3-IIa
, conferring gentamicin resistance, and was highly related to pC15-1a, a plasmid encoding the CTX-M-15 enzyme in Canada. By contrast, pEK204 (strain C; 93,732 bp) belonged to incompatibility group IncI1 and carried only two resistance genes,
bla
CTX-M-3
and
bla
TEM-1
. It probably arose by the transposition of Tn
3
and IS
Ecp1
-
bla
CTX-M-3
elements into a pCOLIb-P9-like plasmid. We conclude that (i) United Kingdom variants of the successful
E. coli
ST131 clone have acquired different plasmids encoding CTX-M ESBLs on separate occasions, (ii) the
bla
CTX-M-3
and
bla
CTX-M-15
genes on pEK204 and pEK499/pEK516 represent separate escape events, and (iii) IncFII plasmids harboring
bla
CTX-M-15
have played a crucial role in the global spread of CTX-M-15 ESBLs in
E. coli
.
CS-8958, a Prodrug of the Novel Neuraminidase Inhibitor R-125489, Demonstrates a Favorable Long-Retention Profile in the Mouse Respiratory Tract
Authors: Koyama Kumiko , Takahashi Makoto , Oitate Masataka , Nakai Naoko , Takakusa Hideo , Miura Shin-ichi , Okazaki Osamu
Published: August 2009

CS-8958 is a prodrug of the pharmacologically active form R-125489, a selective neuraminidase inhibitor, and has long-acting anti-influenza virus activity in vivo. In this study, the tissue distribution profiles after a single intranasal administration of CS-8958 (0.5 μmol/kg of body weight) to mice were investigated, focusing especially on the retention of CS-8958 in the respiratory tract by comparing it with R-125489 and a marketed drug, zanamivir. After administration of [
14
C]CS-8958, radioactivity was retained in the respiratory tract over long periods. At 24 h postdose, the radioactivity concentrations after administration of [
14
C]CS-8958 were approximately 10-fold higher in both the trachea and the lung than those of [
14
C]R-125489 and [
14
C]zanamivir. The [
14
C]CS-8958-derived radioactivity present in these two tissues consisted both of unchanged CS-8958 and of R-125489 at 1 h postdose, while only R-125489, and no other metabolites, was detected at 24 h postdose. After administration of unlabeled CS-8958, CS-8958 was rapidly eliminated from the lungs, whereas the lung R-125489 concentration reached a maximum at 3 h postdose and gradually declined, with an elimination half-life of 41.4 h. The conversion of CS-8958 to R-125489 was observed in mouse trachea and lung S9 fractions and was inhibited by esterase inhibitors, such as diisopropylfluorophosphate and bis-
p
-nitrophenylphosphate. These results demonstrated that CS-8958 administered intranasally to mice was efficiently converted to R-125489 by a hydrolase(s) such as carboxylesterase, and then R-125489 was slowly eliminated from the respiratory tract. These data support the finding that CS-8958 has potential as a long-acting neuraminidase inhibitor, leading to significant efficacy as an anti-influenza drug by a single treatment.
Two Distinct Major Facilitator Superfamily Drug Efflux Pumps Mediate Chloramphenicol Resistance in
Streptomyces coelicolor
Authors: Vecchione James J. , Alexander Blair , Sello Jason K.
Published: August 2009

Chloramphenicol, florfenicol, and thiamphenicol are used as antibacterial drugs in clinical and veterinary medicine. Two efflux pumps of the major facilitator superfamily encoded by the
cmlR1
and
cmlR2
genes mediate resistance to these antibiotics in
Streptomyces coelicolor
, a close relative of
Mycobacterium tuberculosis
. The transcription of both genes was observed by reverse transcription-PCR. Disruption of
cmlR1
decreased the chloramphenicol MIC 1.6-fold, while disruption of
cmlR2
lowered the MIC 16-fold. The chloramphenicol MIC of wild-type
S. coelicolor
decreased fourfold and eightfold in the presence of reserpine and Phe-Arg-β-naphthylamide, respectively. These compounds are known to potentiate the activity of some antibacterial drugs via efflux pump inhibition. While reserpine is known to potentiate drug activity against gram-positive bacteria, this is the first time that Phe-Arg-β-naphthylamide has been shown to potentiate drug activity against a gram-positive bacterium.
The Purified and Recombinant
Legionella pneumophila
Chaperonin Alters Mitochondrial Trafficking and Microfilament Organization
Authors: Chong Audrey , Lima Celia A. , Allan David S. , Nasrallah Gheyath K. , Garduño Rafael A.
Published: August 2009

A portion of the total cellular pool of the
Legionella pneumophila
chaperonin, HtpB, is found on the bacterial cell surface, where it can mediate invasion of nonphagocytic cells. HtpB continues to be abundantly produced and released by internalized
L. pneumophila
and may thus have postinvasion functions. We used here two functional models (protein-coated beads and expression of recombinant proteins in CHO cells) to investigate the competence of HtpB in mimicking early intracellular trafficking events of
L. pneumophila
, including the recruitment of mitochondria, cytoskeletal alterations, the inhibition of phagosome-lysosome fusion, and association with the endoplasmic reticulum. Microscopy and flow cytometry studies indicated that HtpB-coated beads recruited mitochondria in CHO cells and U937-derived macrophages and induced transient changes in the organization of actin microfilaments in CHO cells. Ectopic expression of HtpB in the cytoplasm of transfected CHO cells also led to modifications in actin microfilaments similar to those produced by HtpB-coated beads but did not change the distribution of mitochondria. Association of phagosomes containing HtpB-coated beads with the endoplasmic reticulum was not consistently detected by either fluorescence or electron microscopy studies, and only a modest delay in the fusion of TrOv-labeled lysosomes with phagosomes containing HtpB-coated beads was observed. HtpB is the first
Legionella
protein and the first chaperonin shown to, by means of our functional models, induce mitochondrial recruitment and microfilament rearrangements, two postinternalization events that typify the early trafficking of virulent
L. pneumophila
.
Cryptosporidium parvumIsolate-Dependent Postinfectious Jejunal Hypersensitivity and Mast Cell Accumulation in an Immunocompetent Rat Model
Authors: Khaldi Samira , Gargala Gilles , Le Goff Laetitia , Parey Simon , Francois Arnaud , Fioramonti Jean , Ballet Jean-Jacques , Dupont Jean-Paul , Ducrotté Philippe , Favennec Loïc
Published: August 2009

Cryptosporidiumspp. are a cause of self-limited diarrhea in immunocompetent hosts. In immunocompetent rats,Cryptosporidium parvuminfection induced digestive hypersensitivity, a key pathophysiological factor in functional digestive disorders such as irritable bowel syndrome (IBS). In such a rat model, we sought to document whether jejunal hypersensitivity depends onC. parvumisolate and is associated with a mast cell accumulation. Five-day-old rats were orally administered 105oocysts of either Nouzilly (NoI) or Iowa (IoI)C. parvumisolate. NoI-infected rats exhibited the lowest food intake on days 7 and 14 postinfection (p.i.). On day 7 p.i., small intestine villus atrophy, crypt hyperplasia, and inflammatory cell infiltration were prominent in NoI-infected rats, with higher numbers ofCryptosporidiumforms than in IoI-infected rats. Compared to uninfected control rats, jejunal intraepithelial lymphocytes (IELs) were increased only in NoI-infected rats on day 14 p.i. On day 50 p.i., jejunal hypersensitivity to distension was found only in NoI-infected rats; this hypersensitivity is associated with activated mast cell accumulation. The number of mast cells in the jejunal lamina propria was increased from day 36 p.i. in NoI-infected rats and only at day 120 p.i. in IoI-infected rats. Our data suggest that both the severity of infection (weight loss, reduced food intake, villus atrophy, and IEL accumulation) and the onset of a jejunal hypersensitivity after infection in association with an activated mast cell accumulation are isolate dependent and related to NoI infection. This cryptosporidiosis rat model is a relevant model for the study of underlying mechanisms of postinfectious IBS-like symptoms.