The protective effect of L-arginine on ischemia-reperfusion injury in rat skin flaps

The objective of this study was to examine whether the administration of L-arginine, a precursor of nitric oxide and substrate of nitric oxide synthase, prior to reperfusion could lead to decrease in neutrophil-mediated tissue injury and improved flap survival. Epigastric island skin flaps were elevated in 70 rats and rendered ischemic. Thirty minutes prior to reperfusion, the rats were treated with intraperitoneal saline (n = 15), L-arginine (n = 15), D-arginine (n = 15), or N omega-nitro-L-arginine methylester plus L-arginine in equimolar amounts (n = 15). Flap survival at 7 days and neutrophil counts at 24 hours were evaluated. Flap necrosis as expected in the sham group of animals (n = 10) was 0.0 percent, while the control (saline-treated) animals had 59.6 percent necrosis. Animals treated with L-arginine demonstrated a significant decrease in flap necrosis to 12.7 percent. This protective effect was almost completely negated by N omega-nitrol-L-arginine methylester, which significantly increased flap necrosis to 49.3 percent and was much less pronounced with D-arginine (28.6 percent). Neutrophil counts were significantly decreased in flaps from L-arginine-treated and sham animals versus both saline and N omega-nitro-L-arginine methylester-treated groups. We conclude that administration of L-arginine prior to reperfusion can significantly reduce the extent of flap necrosis and flap neutrophil counts due to ischemia-reperfusion injury. This protective effect is completely negated by nitric oxide synthase inhibition. Since L-arginine reduces the number of neutrophils within the flap and the extent of flap necrosis only in the presence of active nitric oxide synthase, we hypothesize that this protective effect of L-arginine on ischemia-reperfusion injury is secondary to a nitric oxide-mediated suppression of neutrophil-mediated injury.     

Understanding and controlling the scarring response: the contribution of histology and microscopy

In response to injury, the body usually initiates a full and swift wound healing response resulting in reconstructed, repaired tissue. In certain instances, due to a variety of factors, this may not happen, an example being chronic granulating venous leg ulcers. At the other extreme, the wound may heal excessively, producing disabling hypertrophic scarring such as can occur following large, deep burn injuries. Our group is interested in the surgical treatment of the eye disease glaucoma. As will be explained, the successful surgical treatment of this disease depends on a reduced scarring response at the end of wound healing. The purpose of this article is to give an overview of our microscopic and histological experimental work which has furthered our understanding of tissue repair, particularly the scarring response and its potential modification for successful glaucoma surgery.     

Cloning, cDNA sequence analysis and patch clamp studies of a toxin from the venom of the armed spider (Phoneutria nigriventer)

The cDNAs (Tx3-2 and Pn3A) encoding precursor of toxin Tx3-2 and an isoform called Pn3A have been isolated from a library constructed from stimulated venom glands of the spider Phoneutria nigriventer. The cDNA of Tx3-2 reveals the presence of a signal peptide of 21 amino acids and of an intervening propeptide (with 16 amino acids) preceding the toxin sequence, which was followed by additional amino acid residues at the C-terminus (C-terminal peptide), implying post-translational modifications of the synthesised peptide. The deduced amino acid sequence for the mature toxin confirms the previous sequence published. In addition, by using the whole-cell patch clamp technique, we have determined that purified Tx3-2 decreases L-type currents present in GH3 cells. Finally, the presence of the cDNA Pn3A, with high sequence identity with Tx3-2, reveals the existence of a putative new toxin showing, at the cDNA level, 85.4% identity in its whole segment.     

Topical Delivery of Avastin to the Posterior Segment of the Eye In Vivo Using Annexin A5‐associated Liposomes

Effective delivery to the retina is presently one of the most challenging areas in drug development in ophthalmology, due to anatomical barriers preventing entry of therapeutic substances. Intraocular injection is presently the only route of administration for large protein therapeutics, including the anti‐Vascular Endothelial Growth Factors Lucentis (ranibizumab) and Avastin (bevacizumab). Anti‐VEGFs have revolutionised the management of age‐related macular degeneration and have increasing indications for use as sight‐saving therapies in diabetes and retinal vascular disease. Considerable resources have been allocated to develop non‐invasive ocular drug delivery systems. It has been suggested that the anionic phospholipid binding protein annexin A5, may have a role in drug delivery. In the present study we demonstrate, using a combination of in vitro and in vivo assays, that the presence of annexin A5 can significantly enhance uptake and transcytosis of liposomal drug carrier systems across corneal epithelial barriers. This system is employed to deliver physiologically significant concentrations of Avastin to the posterior of the rat eye (127 ng/g) and rabbit retina (18 ng/g) after topical application. Our observations provide evidence to suggest annexin A5 mediated endocytosis can enhance the delivery of associated lipidic drug delivery vehicles across biological barriers, which may have therapeutic implications.     

The characterization of high-density polyethylene/organoclay nanocomposites

Polymeric nanocomposites, which are hybrids of polymers and modified inorganic clay with organic surfactants, are extremely attractive in both science and industry. These materials present improvements in such polymer properties as modulus, heat capacity, thermal stability, flame resistance, and so on. Research has been conducted in recent decades to obtain high-quality materials that can be used in applications like food packing, car components, and combustible cells. Polymeric nanocomposites present many advantages in relation to composites due to the quantity of filler added to the polymer and also to the improved properties. In a composite, the quantity of filler must be as high as possible (i.e., over 30%). In the polymeric nanocomposite the quantity of filler varies from 1% to 5% because of the nanosize of the particles. These nanoparticles often have a large surface area that results in improved polymer-matrix properties.     

Behaviour of coatings with AWS ERNiCrMo-3 electrode on ASTM A516 Gr.60 steel in ageing tests

This work is intended to evaluate the microstructure of nickel-based overlay welds after ageing heat treatments. GMA welds using an AWS ERNiCrMo-3 electrode were deposited with a robot on ASTM A516 Gr.60 steel. Two weld heat inputs were used, 1.0 and 1.4 kJ/mm, with a current of 290 A, arc voltage of 33 V, and welding speeds of 9.7 and 6.8 mm/s, respectively. The ageing processes were conducted at 600°C using times of 100 and 300 h. Micro-hardness profiles and scanning electron microscopy together with energy dispersive spectrometry analysis were carried out to characterize the overlay. The hardness profile indicated that, in the ‘as welded’ condition, the overlay and heat-affected zone (HAZ) hardness were about 240 and 190 VH, respectively. The ageing process decreased the HAZ hardness to 120 VH and increased the overlay hardness to 290 VH after 100 h and to 310 VH after 300 h. These changes occurred due to HAZ decarburization and transformation of micro phases. After ageing, hard zones with values of around 800 VH were observed in the partially diluted zone, caused by the higher concentration of carbides and microstructural changes.     

Body Area Networking: Technology and Applications

The six articles in this special issue focus on the technology and applications of body area networking.     

Evaluating the influence of the width of inlet slot on the prediction of indoor airflow: Comparison with experimental data

The aim of this work is to investigate the influence of two values of inlet slot width on the velocity characteristics and turbulent intensity of the airflow inside a rectangular room. The experimental data used to check the numerical results concerns a rectangular room where the air is supplied horizontally on the upper left and is exhausted through an opening on the lower right on the opposite side. The performance of three turbulence models, standard k-?, RNG k-?, and k-ω, in predicting the three-dimensional airflow in that room has also been investigated. The results for Reynolds number of 5000 are presented for dimensionless horizontal velocities and turbulent kinetic energy for two planes of the room and two inlet arrangements, one opening as large as the room and another with half of the width of the room. The results have indicated that the main features of the flow were captured by the three turbulence models investigated. On the whole, the performance of the standard k-? model was better than those of the other two turbulence models. In particular, the k-ω model performed better in the configuration with the largest air opening than in that with the smallest one, while the RNG k-? model presented the opposite behavior. The comparative study between both geometries demonstrated that for slots much smaller than the width of the room, three-dimensional effects become important.     

Medical-surgical nursing: a new teaching approach and its evaluation by the student

This issue is about a teaching methodology developed by the Medical-Surgical subject of Nursing on Graduate Course at Universidade Estadual de Londrina. The teachers used the student-centered teaching process based on interpersonal relationship and problem solving method. The aim was to evaluate the last period of nursing students perception about developing of cognitive, affective and psychomotor abilities when compared with others subjects of nursing course since 1985 until 1990. This method of teaching supplied more integration among theory and practice, more ability in developing library search and oral exposition, besides more active student participation on his apprenticeship process.     

The seasonality of meningococcal disease in infants less than 1 year old. Cuba, 1983-1990

Variation of ethanol and acetaldehyde concentrations in blood, catecholamines in hypothalamus, brain stem and hemispheres, heart and adrenal glands, serotonin in the same structures of the brain, thin intestine and blood in rats was studied. Isolated action of medichronal during 10 days against the background of prolonged administration of moderate doses of ethanol significantly lowered ethanol and acetaldehyde concentration in the animal blood. Medichronal increased the level of noradrenaline, lowered under the conditions of ethanol intoxication in the hypothalamus, and increased adrenalina level in the heart; noradrenaline level in adrenal glands is restored. The amount of serotonin in the blood and tissues increased under the conditions of ethanol intoxication did not vary under the action of medichronal. The obtained results indicate to pronounced detoxication influence of medichronal. One of the mechanisms of its action is normalizing the catecholamine changes caused by the ethanol intoxication in tissues.