Experimental pig yersiniosis to assess attenuation of Yersinia enterocolitica O:8 mutant strains

An experimental oral pig model was used to assess the pathogenic and immunogenic potential of Yersinia enterocolitica serotype O:8 wild-type strain 8081-L2 and its lipopolysaccharide (LPS) mutant derivatives: a spontaneous rough mutant 8081-R2, strain 8081-DeltawzzGB expressing O-antigen with uncontrolled chain lengths, and strain 8081-wbcEGB expressing semirough LPS with only one O-unit. Microbiological and immunological parameters of the infected pigs were followed from day 7 to 60 postinfection. The wild-type and all LPS mutant strains persisted in the lymphoid tissue of tonsils and small intestines, causing asymptomatic infection without any pathological changes. Although the pig is known as a reservoir of Yersiniae, a precise analysis of pathogenic and immunogenic parameters based on different in vitro tests (hematological response, killing ability of leukocytes and blood sera, antibody response, hydrogen peroxide production by macrophages, classical and alternative pathways of complement activation), revealed significant attenuation in the pathogenicity of the LPS mutant strains but not the loss of immunogenic potential. In comparison with the other strains, strain 8081-DeltawzzGB demonstrated more continuous leucocytosis with monocytosis, higher invasive potential, significant activation of hydrogen peroxide production by macrophages and an effective immunoglobulin G immune response accompanied by relevant histological immunomorphological rearrangements.

Attenuation of urokinase activity during experimental ischaemia protects the cerebral barrier from damage through regulation of matrix metalloproteinase-2 and NAD(P)H oxidase

Ischaemic injury impairs the integrity of the blood-brain barrier (BBB). In this study, we investigated the molecular causes of this defect with regard to the putative correlations among NAD(P)H oxidase, plasminogen-plasmin system components, and matrix metalloproteinases. Hence, the activities of NAD(P)H oxidase, matrix metalloproteinase-2, urokinase-type plasminogen activator (uPA), and tissue-type plasminogen activator (tPA), and superoxide anion levels, were assessed in human brain microvascular endothelial cells (HBMECs) exposed to oxygen-glucose deprivation (OGD) alone or OGD followed by reperfusion (OGD + R). The integrity of an in vitro model of BBB comprising HBMECs and astrocytes was studied by measuring transendothelial electrical resistance and the paracellular flux of albumin. OGD with or without reperfusion (OGD ± R) radically perturbed barrier function while concurrently enhancing uPA, tPA and NAD(P)H oxidase activities and superoxide anion release in HBMECs. Pharmacological inactivation of NAD(P)H oxidase attenuated OGD ± R-mediated BBB damage through modulation of matrix metalloproteinase-2 and tPA, but not uPA activity. Overactivation of NAD(P)H oxidase in HBMECs via cDNA electroporation of its p22-phox subunit confirmed the involvement of tPA in oxidase-mediated BBB disruption. Interestingly, blockade of uPA or uPA receptor preserved normal BBB function by neutralizing both NAD(P)H oxidase and matrix metalloproteinase-2 activities. Hence, selective targeting of uPA after ischaemic strokes may protect cerebral barrier integrity and function by concomitantly attenuating basement membrane degradation and oxidative stress.

Retinal microvascular network attenuation in Alzheimer's disease

INTRODUCTION:Cerebral small-vessel disease has been implicated in the development of Alzheimer’sdisease (AD). The retinal microvasculature enables non-invasive visualization andevaluation of the systemic microcirculation. We evaluated retinal microvascular parametersin a case-control study of AD patients and cognitively-normal controls. 

METHODS:Retinal images were computationally analyzed and quantitative retinal parameters (caliber,fractal dimension, tortuosity, and bifurcation) measured. Regression models were used tocompute odds ratios (OR) and confidence intervals (CI) for AD with adjustment forconfounders. 

RESULTS:Retinal images were available in 213 AD participants and 294 cognitively-normal controls.Persons with lower venular fractal dimension (OR per standard deviation [SD] increase, 0.77[CI: 0.62–0.97]) and lower arteriolar tortuosity (OR per SD increase, 0.78 [CI: 0.63–0.97])were more likely to have AD following appropriate adjustment. 
DISCUSSION:Patients with AD have a sparser retinal microvascular network and retinal microvascularvariation may represent similar pathophysiological events within the cerebralmicrovasculature of patients with AD.

Ultrasonic attenuation in layered superconductors /

We study the ultrasonic attenuation in layered superconductors using the Green's function formalism. General expressions are derived analytically and then calculated numerically by taking the nearest and next-nearest interactions in a disordered layered superconductor with random hoppings. Our results show huge anisotropics of ultrasonic attenuation in the superconductors and the strong dependence of ultrasonic attenuation on the temperature and the direction of polarization of the sound wave.

Attenuation of skeletal muscle FFA-induced insulin resistance by the polyphenol resveratrol. Elucidation of the mechanisms involved

Excess plasma free fatty acids (FFA) are correlated with insulin resistance and are a risk factor for the development of type 2 diabetes. In this study we examined the effect of the polyphenol resveratrol on FF A-induced insulin resistance in skeletal muscle cells and the mechanisms involved. Incubation of L6 myotubes with the FF A palmitate significantly decreased the insulin-stimulated glucqse uptake. Importantly, the effect of palmitate was ameliorated by resveratrol. Palmitate significantly increased serine phosphorylation of IRS..; 1 and reduced insulin-stimulated Akt phosphorylation, an effect that was abolished by resveratrol. We then investigated the effect of palmitate and resveratrol on the expression and phosphorylation of JNK, mTOR, p70-S6K, and AMPK kinases. The results demonstrated that our treatments had no effect on the expression of these proteins. However, palmitate increased the phosphorylation of mTOR and p70- S6K, whereas resveratrol abolished this effect and increased the phosphorylation of AMPK. Furthermore, all effects of resveratrol were abolished with sirtuin inhibitors, sirtinol and nicotinamide. These results indicate that resveratrol ameliorated FF A-induced insulin resistance by regulating mTOR and p70-S6K phosphorylation in skeletal muscle cells, through a mechanism involving sirtuins.

A multiple-building diffraction attenuation function expressed in terms of UTD coefficients for microcellular communications

This work presents an explicit formulation for multiple- edge diffraction for mobile radiowave propagation in terms of uniform theory of diffraction (UTD) coefficients when a spherical incident wave is considered. This solution can be used in an UTD context and sharply reduces the computing time over existing formulation. Results can be applied in the planning of microcellular systems

Effect of dissolved NaCl, MgCl2, and Na2SO4 in seawater on the optical attenuation in the region from 430 to 630 nm

The split-pulse laser method is used to reinvestigate the optical attenuation of distilled water in the region from 430 to 630 nm. The studies are then extended to ionic solutions of NaCl, MgCl2, and Na2SO4, these salts forming the major constituents of seawater. The effect of the concentration of these constituents on optical attenuation is investigated. Further, optical attenuation studies are carried out for the region from 430 to 630 nm for an aqueous solution prepared with all the major constituents in the same proportions as in natural seawater. These values are then compared with values obtained for natural seawater. The relative role of dissolved salts and suspended particles on optical attenuation in seawater is discussed. The lowest attenuation is observed at ~450 nm for all solutions and is found to coincide with that for distilled water.

Studies on optical attenuation in sea water using dye laser and laser propagation in a turbulent medium

The central theme of the work presented in this thesis is a careful investigation of the factors influencing the attenuation of laser beam through sea water. The thesis presents a detailed report of the work done by the author on the attenuation studies in sea water and on laser propagation through a turbulent medium. The thesis contains six chapters which are more or less self-contained with separate abstracts and references. The first chapter is divided into two parts. The first part introduces the subject of laser propagation through sea water. It includes a brief description of optical properties of sea water followed by a review of the earlier works on attenuation studies in water. The second part gives the theoretical background of the problem of laser propagation through a turbulent medium.

Semiactive backstepping control for vibration attenuation in structures equipped with magnetorheological actuatorscat

This paper deals with the problem of semiactive vibration control of civil engineering structures subject to unknown external disturbances (for example, earthquakes, winds, etc.). Two kinds of semiactive controllers are proposed based on the backstepping control technique. The experimental setup used is a 6-story test structure equipped with shear-mode semiactive magnetorheological dampers being installed in the Washington University Structural Control and Earthquake Engineering Laboratory (WUSCEEL). The experimental results obtained have verified the effectiveness of the proposed control algorithms