M.C. dos Santos

Biochemical and pharmacological similarities between the venoms of newborn Crotalus durissus durissus and adult crotalus durissus terrificus rattlesnakes

A comparative study was performed with the venoms of newborn Crotalus durissus durissus, adult Crotalus durissus terrificus and adult Crotalus durissus durissus snakes. Venom of newborn specimens of C.d. durissus is very similar to that of adult specimens of C.d. terrificus, since they have strong lethal and myotoxic activities, and weak proteolytic, hemorrhagic and edema-forming effects, in contrast to venom of adult specimens of C.d. durissus. In addition, the two former venoms have high amounts of the neurotoxic complex crotoxin, whereas venom from adult C.d. durissus has a low concentration of crotoxin. Electrophoretic analysis corroborates the strong similarities between the former two venoms. It is concluded that venom of newborn C.d. durissus contains high concentrations of crotoxin and low amounts of hemorrhagic and proteolytic components, and that a drastic ontogenetic change takes place in the venom composition of this subspecies.

Antigenic cross-reactivity of venoms obtained from snakes of genus bothrops

Antigenic cross-reactivity was studied among the components of venoms from nine species of the genus Bothrops using species-specific antivenoms. Sera titration by DOT-ELISA detected similar levels of antibody when either homologous or heterologous antigens were used. Transblotted antigens, after SDS-PAGE fractionation, were also revealed by homologous and heterologous antivenoms. Antigens with mol. wt greater than 30,000 seemed to be the most cross-reactive. Antigens of about 24,000 mol. wt were poorly immunogenic. Antigens between 14-18,000 mol. wt cross-reacted only with B. moojeni, B. jararacussu, B. neuwiedi and B. pradoi venoms. Neutralization of the lethality of B. jararaca venom was observed by homologous and heterologous antivenoms.

Nitrogen-substituted nanotubes and nanojunctions: Conformation and electronic properties

We present a theoretical study on the structural and electronic modifications caused by random nitrogen substitution in carbon tubular and branched nanostructures. Finite cluster calculations with hydrogen saturation of the tube ends were performed. Geometry optimizations were carried out through semiempirical quantum chemical calculations. Densities of states (DOS) were calculated by the density functional theory. The energy associated with nitrogen incorporation was obtained. Some tubular structures undergo a length shortening as a consequence of N substitution. DOS analysis is consistent with the shift of the electronic spectrum to lower energies and a more metallic character of the tubes upon nitrogen doping due to the emergence of nitrogen-induced states close to the conduction band. The defective regions of junctions and bends were built including five-, seven-, and eight-membered rings in the otherwise hexagonal network of carbon bonds. In order to reduce the stress caused by the curvature, a chemi...

Effect of Topical Insulin on Second-Degree Burns in Diabetic Rats.

The healing process is complex in diabetic wounds, and the healing mechanism of burn wounds is different from that of incisional or excisional wounds. Data from our previous study indicated that topical insulin cream reduced wound closure time in diabetic rats. Our aim was to investigate the effect of topical insulin cream on wound healing following second-degree burns in control and diabetic rats. Rats were divided into four groups: control (nondiabetic) rats treated with placebo (CP), control (nondiabetic) rats treated with topical insulin cream (CI), diabetic rats treated with placebo (DP), and diabetic rats treated with topical insulin cream (DI). The wounds were assessed at 4 time points (1, 7, 14, and 26 days) post-wounding for morphometric analysis of wound sections stained with hematoxylin/eosin, α-smooth muscle actin, and Picrosirius red to evaluate general aspects of the wound, inflammatory infiltrate, blood vessels, and Types I and III collagen fibers. Histological analysis showed that topical insulin cream increased the inflammatory cell infiltrate in the DI group (at 7 and 14 days postburn, p < .05) and blood vessels (at 14 days postburn, p < .05) to levels similar to those of groups CP and CI. Wounds treated with topical insulin cream (CI and DI groups) showed significantly stronger staining for fibrillar collagen than wounds of the DP group. The use of topical insulin may reduce the duration of the inflammatory phase; improve wound reepithelialization, tissue granulation, and wound contraction; and increase collagen deposition in second-degree burns in healthy and diabetic animals.

Microgravimetric studies of silver electrocrystallization on polycrystalline gold surfaces

Cyclic voltammetry and chronoamperometry were performed in conjunction with electrochemical quartz crystal microbalance studies with the aim of making a new contribution to electrocrystallization studies. The nucleation and growth of silver on polycrystalline gold surfaces was selected as the probe system due to its simplicity and the availability of previous publications. To obtain thin films of silver on gold, the electrochemical experiments were conducted in an ammonium hydroxide solution (pH 11.8). The simultaneous current and mass variation transients obtained allowed for the proposal of a mathematical model, based on the well-established model of Scharifker and Hills (Electrochim. Acta 28 (1983) 879) model, in which parameters such as the number of nuclei and the nucleation rate were determined without contributions from non-faradic currents.

Packaging: function, re-function and malfunction: from consumer society to the homeless material culture

This paper seeks to understand the meaning of packaging in contemporary society. It discusses some technical aspects of packaging as well as its life-cycle, from the consumer society to the homeless material culture. It provides an opportunity to analyse the role of packaging in the material strategies of survival of the homeless. From the preservation of products to the protection of the human body, packaging is in transition at the end of this century, under the impact of globalisation and the increasing poverty of the First and Third Worlds.

Multiple facets of HIV-associated renal disease

HIV infection has a broad spectrum of renal manifestations. This study examined the clinical and histological manifestations of HIV-associated renal disease, and predictors of renal outcomes. Sixty-one (64% male, mean age 45 years) HIV patients were retrospectively evaluated. Clinical presentation and renal histopathology were assessed, as well as CD4 T-cell count and viral load. The predictive value of histological lesion, baseline CD4 cell count and viral load for end-stage renal disease (ESRD) or death were determined using the Cox regression model. The outcomes of chronic kidney disease (CKD) and ESRD or death were evaluated by baseline CD4 cell count. The percent distribution at initial clinical presentation was non-nephrotic proteinuria (54%), acute kidney injury (28%), nephrotic syndrome (23%), and chronic kidney disease (22%). Focal segmental glomerulosclerosis (28%), mainly the collapsing form (HIVAN), acute interstitial nephritis (AIN) (26%), and immune complex-mediated glomerulonephritis (ICGN) (25%) were the predominant renal histology. Baseline CD4 cell count ≥200 cells/mm3 was a protective factor against CKD (hazard ratio=0.997; 95%CI=0.994-0.999; P=0.012). At last follow-up, 64% of patients with baseline CD4 ≥200 cells/mm3 had eGFR >60 mL·min-1·(1.73 m2)-1 compared to the other 35% of patients who presented with CD4 <200 cells/mm3 (log rank=9.043, P=0.003). In conclusion, the main histological lesion of HIV-associated renal disease was HIVAN, followed by AIN and ICGN. These findings reinforce the need to biopsy HIV patients with kidney impairment and/or proteinuria. Baseline CD4 cell count ≥200 cells/mm3 was associated with better renal function after 2 years of follow-up.