Biocompatibility and cutaneous reactivity of cellulosic polysaccharide film in induced skin wounds in rats

The development of a skin substitute suitable for immediately performing the function of the lost dermis and epidermis could result in a positive impact on the treatment of patients with extensive skin lesions. A biopolymer film was applied to skin wounds to investigate the biocompatibility and cutaneous reaction and to test its activity as a mechanical barrier and conductor in the healing process. Forty Wistar rats of both sexes were used in the present study. Two excisions were performed in the dorsal part of the skin flaps. The polysaccharide film was applied over one of the incisions and other incision was washed with saline. The time spent for complete healing of both lesions was virtually the same in both groups, during 21 days of observation. The film remained attached to the bed of the exposed wound for an average period of 6 days. There were no statistically significant differences with regard to lesion measurement area at assessment times of 2nd, 7th and 14th postoperative days. At day 21, the scar area showed a significant difference (0.0229). After 40 days, all wounds were completely healed. No statistically significant differences were found between the histological parameters assessed in the experimental and control groups. The cellulosic polysaccharide film integrated well with the tissue showing high biocompatibility and low skin reactivity.     

Magnetic and nonmagnetic impurities in some A-15 structure systems. II. Magnetic properties

We present measurements of the susceptibility of the A-15 structure systems NbyPt_100–y–x M _x where M = Fe and Ru (y = 73–78). These measurements correlated with those of the critical temperature T _c permit us to conclude that there is a saturation of the effective number of magnetic impurity atoms and that these atoms are situated on the chains. We find also that the magnetic moment of the Fe atoms depend on the value of y. The high value of the Curie temperature and its variation is discussed with the aid of a model of pairs with antiferromagnetic interaction. In order to describe the formation of the localized moments we have taken into account the effect of the environment around each impurity. Depending on the number and the nature of the nearest neighboring atoms, we deduce a magnetic or nonmagnetic behavior of the impurity. The variation of the moment as a function of the nearest neighbors is explained by supposing electronic redistribution between the atoms, which is the same as supposing an interatomic charge transfer.     

First Tests of 6Li Doped Glass Scintillators for Ultracold Neutron Detection

We report the results of test measurements aimed at determining the performances of ⁶Li doped glass scintillators for the detection of ultra-cold neutrons. Four types of scintillators, GS1, GS3, GS10 and GS20, which differ by their ⁶Li concentrations, have been tested. The signal to background separation is fully acceptable. The relative detection efficiencies have been determined as a function of the neutron velocity. We find that GS10 has a higher efficiency than the others for the detection of neutrons with velocities below 7 m/s. Two pieces of scintillators have been irradiated with a high flux of cold neutrons to test the radiation hardness of the glasses. No reduction in the pulse height has been observed up to an absorbed neutron dose of 1 × 10¹³ cm⁻³.     

A framework for network quality monitoring in the VoIP environment

Monitoring speech quality in Voice over IP (VoIP) networks is important to ensure a minimal acceptable level of speech quality for IP calls running through a managed network. Information such as packet loss, codec type, jitter, end‐to‐end delay and overall speech quality enables the network manager to verify and accurately tune parameters in order to adjust network problems. The present article proposes the deployment of a monitoring architecture that collects, stores and displays speech quality information about concluded voice calls. This architecture is based on our proposed MIB (Management Information Base) VOIPQOS, deployed for speech quality monitoring purposes. Currently, the architecture is totally implemented, but under adjustment and validation tests. In the future, the VOIPQOS MIB can be expanded to automatically analyze collected data and control VoIP clients and network parameters for tuning the overall speech quality of ongoing calls. Copyright © 2006 John Wiley & Sons, Ltd.     

Ultrastructural changes in the trabecular meshwork of human eyes treated with corticosteroids

OBJECTIVES: To study the ultrastructure of the trabecular meshwork in human eyes with corticosteroid-induced glaucoma and to determine whether the changes noted also occur in the eyes of patients with primary open-angle glaucoma (POAG) who have been treated with corticosteroids. METHODS: The trabecular meshwork from 5 patients in whom corticosteroid-induced glaucoma was diagnosed and from 6 patients with POAG who had been treated with systemic or topical corticosteroids for months to years was investigated with light and electron microscopy. None of the eyes with POAG were considered to have corticosteroid-induced elevation of the intraocular pressure. RESULTS: Eyes with corticosteroid-induced glaucoma had the accumulation of extracellular material distinct from the sheath-derived plaques typical of POAG. A finger-printlike arranged material resembling basement membranes (FBM material), considered characteristic of corticosteroid-induced glaucoma, was found in all eyes with corticosteroid-induced glaucoma. In addition, an abnormal accumulation of densely packed, fine fibrils immediately beneath the inner wall endothelium of Schlemm's canal was present. The findings were similar among patients receiving topical or systemic treatment and among patients of different ages. In the eyes from donors with POAG who had been treated with corticosteroids, the fine fibrillar material and FBM material were present in small amounts in 3 of 6 donors and were not found in the other 3 donors. CONCLUSIONS: The extracellular material that accumulates in eyes with corticosteroid-induced glaucoma differs from that seen in eyes with POAG. Eyes with POAG exposed to long-term corticosteroid treatment did not all respond with the formation of the abnormal extracellular materials characteristic of those found in eyes with corticosteroid-induced glaucoma.     

Beta-adrenoceptors in the tree shrew brain. I. Distribution and characterization of [125I]iodocyanopindolol binding sites

Extracellular, single unit recording techniques were used to measure the responses of posterior lateral line nerve fibers to a 50-Hz dipole source that slowly changed its location along the length of the fish. The flow-field equations for a dipole source were used to model the pressure gradient pattern and thus, the expected excitation pattern along a linear array of lateral line receptor organs for different source locations. Finally, excitation patterns were similarly modeled along the left and right side of the fish's head for actual steps taken by sculpin in approach pathways to the 50-Hz dipole source. Spatial histograms of posterior lateral line nerve fiber responses to different locations of the dipole source could be predicted from pressure gradient patterns modeled from the flow-field equations, confirming that the modeling approach applied to behavioral results was a good predictor of excitation patterns likely to be encoded by the lateral line periphery. An examination of how modeled excitation patterns changed from one position to the next in typical approach pathways and how patterns differed between positions from which successful and unsuccessful strikes were launched suggests that approach and strike strategies can indeed be explained by the information available in excitation patterns. In particular, changes in the spatial distribution of pressure gradient directions (polarities), available only when the source is lateral (as opposed to directly in front of the fish), appear to enhance the ability of sculpin to determine source distance. Without such information, misses are more likely to occur and successful strikes are more likely to be launched from short distances only.     

Synthesis, hydration and durability of rice hull cements doped with chromium

This work describes the synthesis, hydration and durability behavior of β-Ca(2)SiO(4) doped with chromium. β-Ca(2)SiO(4) is a component of commercial cement. Rice hull is an agricultural residue containing about 10% of silica as inorganic constituent. The controlled burning of rice hull was used to obtain this biogenic silica, used as starting material. In many situations chromium is added during cement preparation in order to promote encapsulation, at temperatures around 1500°C. The synthesis presented here is completed at 800°C, causing a substantial reduction in energy consumption. Moreover, chromium is chemically bonded to cement crystal, which is safer than simple physical encapsulation. Results show that chromium can be inserted into the structure of β-Ca(2)SiO(4) up to 1% (molar ratio). Hydration degree and durability studies show that insertion of chromium causes no deleterious effects on physical and chemical properties of these doped materials when compared to β-pure Ca(2)SiO(4).