Antimicrobial effects of various flavonoids on Escherichia coli O157:H7 cell growth and lipopolysaccharide production

Flavonoids have biofunctional effects as antioxidant and antimicrobial agents. The objective of this study was to evaluate the bactericidal activity and antilipopolysaccharide (LPS) effects of flavonoids on Escherichia coli O157:H7. The effects of flavonoids on the growth of E. coli O157:H7 were bacteriostatic rather than bactericidal at concentrations below 200 μM, and there was no significant difference among the flavonoids tested (p<0.05). LPS production in E. coli O157:H7 treated with 200 μM quercetin and naringenin decreased by 34.06±1.03 and 19.90±1.51%, respectively, relative to the control (no flavonoid). Luteolin, genkwanin, hesperetin, and apigenin caused decreases in LPS production of 69.85±1.03, 61.18±1.15, 60.74±1.10, and 58.93±0.98%, respectively, relative to the control. Based on these results, luteolin had the greater inhibitory effect on LPS production by E. coli O157:H7 than other flavonoids tested in this study.     

3,4-Methylenedioxymethamphetamine Alters Left Ventricular Function and Activates Nuclear Factor-Kappa B (NF-κB) in a Time and Dose Dependent Manner

3,4-Methylenedioxymethamphetamine (MDMA) is an illicit psychoactive drug with cardiovascular effects that have not been fully described. In the current study, we observed the effects of acute MDMA on rabbit left ventricular function. We also observed the effects of MDMA on nuclear factor-kappa B (NF-κB) activity in cultured rat ventricular myocytes (H9c2). In the rabbit, MDMA (2 mg/kg) alone caused a significant increase in heart rate and a significant decrease in the duration of the cardiac cycle. Inhibition of nitric oxide synthase (NOS) by pretreatment with L-NAME (10 mg/kg) alone caused significant dysfunction in heart rate, systolic pressure, diastolic pressure, duration of relaxation, duration of cardiac cycle, and mean left ventricular pressure. Pretreatment with L-NAME followed by treatment with MDMA caused significant dysfunction in additional parameters that were not abnormal upon exposure to either compound in isolation: duration of contraction, inotropy, and pulse pressure. Exposure to 1.0 mM MDMA for 6 h or 2.0 μM MDMA for 12 h caused increased nuclear localization of NF-κB in cultured H9c2 cells. The current results suggest that MDMA is acutely detrimental to heart function and that an intact cardiovascular NOS system is important to help mitigate early sequelae in some functional parameters. The delayed timing of NF-κB activation suggests that this factor may be relevant to MDMA induced cardiomyopathy of later onset.     

A Multi‐Block Approach to Obtain Angle‐Resolved PIV Measurements of the Mean Flow and Turbulence Fields in a Stirred Vessel

Two‐dimensional Particle Image Velocimetry (PIV) measurements have been used to characterize the complex turbulent flow generated by a T/3 45° pitched‐blade down‐flow turbine, operated at Re ≈ 5 · 10⁴, in a fully turbulent stirred vessel. To maintain high spatial resolution when viewing the whole vessel, a multi‐block approach has been developed, which combines data from different fields of view into a composite flow map. Using 500 measurements of instantaneous u and v velocity fields, angle‐resolved mean velocity maps and turbulence properties, such as the RMS velocities and the turbulence kinetic energy, have been estimated near to the blade, as well as in the bulk of the vessel, at a spatial resolution of between 1 and 2 mm. Vorticity maps have also been calculated to help visualize the trailing vortex structures close to the impeller blades and integral length scales have been estimated from the two‐dimensional spatial auto‐correlation function. It is shown than the common assumption that the integral length scale is about half the blade width is an overestimate close to the impeller and an underestimate far from the impeller.     

Preliminary screening of Bifidobacteria spp. and Pediococcus acidilactici in a Swiss cheese curd slurry model system: Impact on microbial viability and flavor characteristics

A Swiss cheese curd slurry model system was used as a preliminary screening method to determine the feasibility of the incorporation of probiotic bacteria (Bifidobacterium breve R0070, Bifidobacterium infantis R0033, Bifidobacterium longum R0175, and Pediococcus acidilactici R1001) into Swiss cheese. The cheese curd was inoculated with probiotic bacteria (8.0 log₁₀ cfu g⁻¹) and ripened anaerobically for 0, 7, and 10 days at 37 °C. Following ripening, counts of the probiotic bacteria increased to 9–10 log₁₀ cfu g⁻¹, with no significant difference in the viability of the four probiotic bacteria. Viable populations of Swiss cheese background microflora in the presence of each probiotic culture were comparable with the control. Ripening time, and to a lesser extent probiotic treatment had a significant effect on the content of several volatile flavor compounds. Similarly, ripening time contributed to a significant increase in the content of a majority of the free amino acids. The study demonstrated the feasibility of the incorporation of probiotic bacteria into Swiss cheese to produce a functional food.     

Projection structure of frog rhodopsin in two crystal forms

Rhodopsin is the G protein-coupled receptor that upon light activation triggers the visual transduction cascade. Rod cell outer segment disc membranes were isolated from dark-adapted frog retinas and were extracted with Tween detergents to obtain two-dimensional rhodopsin crystals for electron crystallography. When Tween 80 was used, tubular structures with a p2 lattice (a = 32 A, b = 83 A, gamma = 91 degrees) were formed. The use of a Tween 80/Tween 20 mixture favored the formation of larger p22(1)2(1) lattices (a = 40 A, b = 146 A, gamma = 90 degrees). Micrographs from frozen hydrated frog rhodopsin crystals were processed, and projection structures to 7-A resolution for the p22(1)2(1) form and to 6-A resolution for the p2 form were calculated. The maps of frog rhodopsin in both crystal forms are very similar to the 9-A map obtained previously for bovine rhodopsin and show that the arrangement of the helices is the same. In a tentative topographic model, helices 4, 6, and 7 are nearly perpendicular to the plane of the membrane. In the higher-resolution projection maps of frog rhodopsin, helix 5 looks more tilted than it appeared previously. The quality of the two frog rhodopsin crystals suggests that they would be suitable to obtain a three-dimensional structure in which all helices would be resolved.     

Analysis of pulsed wave Doppler ultrasound spectra obtained from amodel intracoronary catheter

Abnormal arterial blood flow patterns have been implicated in the evolution of various vascular disease processes. Intravascular ultrasound techniques using the pulsed wave Doppler catheter offer the opportunity to characterize these abnormal flow patterns. The authors have developed a mathematical model that predicts the first two moments of the Doppler spectrum obtained using a Doppler catheter based on the distribution of ultrasonic beam power and velocity profile of fluid flow with an arbitrary distribution of flow disturbances. A scaled-up, in vitro experimental arterial system was used to confirm the validity of the model. Comparison of the predicted first two moments of the Doppler spectrum to the experimental values in this system demonstrated that the distribution of beam power significantly affects the magnitude of the first two moments. Additionally, both velocity gradient and velocity fluctuation broadening effects play prominent roles in determining the magnitude of the second moment. These phenomena must therefore be considered when evaluating in vivo Doppler spectra used for the characterization of abnormal flow patterns     

Pathological and genetic correlates of apoptosis in the progression of colorectal neoplasia

Recent data indicate that dysphagia may occur following unilateral cortical stroke; however, the elucidation of specific cytoarchitectonic sites that produce deglutition disorders remains unclear. In a previous study of unilateral cortical stroke patients with dysphagia, Daniels et al. proposed that the insula may be important in swallowing as it was the most common lesion site in the patients studied. Therefore, 4 unilateral stroke patients with discrete lesions of the insular cortex were studied to further facilitate understanding of the role of the insula in swallowing. Dysphagia, as confirmed by videofluoroscopy, was evident in 3 of the 4 patients; all had lesions that involved the anterior insula, whereas the only patient without dysphagia had a lesion restricted to the posterior insula. These data suggest that the anterior insula may be an important cortical substrate in swallowing. The anterior insula has connections to the primary and supplementary motor cortices, the ventroposterior medial nucleus of the thalamus, and to the nucleus tractus solitarius, all of which are important regions in the mediation of oropharyngeal swallowing. Therefore, discrete lesions of the anterior insula may disrupt these connections and, thereby, produce dysphagia.