Phase transitions in biodegradable films based on blends of gelatin and poly (vinyl alcohol)

The aim of this work was to study the effect of the hydrolysis degree (HD) and the concentration (C PVA) of two types of poly (vinyl alcohol) (PVA) and the effect of the type and the concentration of plasticizers on the phase properties of biodegradable films based on blends of gelatin and PVA, using a response-surface methodology. The films were made by casting and the studied properties were their glass (Tg) and melting (Tm) transition temperatures, which were determined by diferential scanning calorimetry (DSC). For the data obtained on the first scan, the fitting of the linear model was statistically significant and predictive only for the second melting temperature. In this case, the most important effect on the second Tm of the first scan was due to the HD of the PVA. In relation to the second scan, the linear model could be fit to Tg data with only two statistically significant parameters. Both the PVA and plasticizer concentrations had an important effect on Tg. Concerning the second Tm of the second scan, the linear model was fit to data with two statistically significant parameters, namely the HD and the plasticizer concentration. But, the most important effect was provoked by the HD of the PVA.

Influence of the Al content on the phase transformations in Cu-Al-Ag alloys

The influence of the Al content on the phase transformations in Cu-Al-Ag alloys was studied by classical differential thermal analysis (DTA), optical microscopy (OM) and X-ray diffractometry (XRD). The results indicated that the increase in the Al content and the presence of Ag decrease the rate of the b1 phase decomposition reaction and contribute for the raise of this transition temperature, thus decreasing the stability range of the perlitic phase resulted from the b1 decomposition reaction.

O estado vítreo dentro da perspectiva do curso de graduação em química (físico-química)

We consider the relevance of the study of the glassy state properties and the glass transition as important topics of the physical chemistry for undergraduate courses of Chemistry. Two of the most important theoretical approaches for the description of the glassy state, the thermodynamic and the kinetic models, are summarized with emphasis on the physical chemistry aspects. Examples illustrating the glass transition of some materials are also presented.

Resina de Protium heptaphyllum: isolamento, caracterização estrutural e avaliação das propriedades térmicas

Three mixtures of triterpenes (maniladiol and breine; alpha and beta-amyrin; lupenone, alpha and beta-amyrinone) were isolated from Protium heptaphyllum March resin. The structural identification was based on NMR and mass spectrometry data. Lupenone, and alpha and beta-amyrinone were not reported before as constituents of this resin. The resin was submitted to methylation and acetylation reactions. The pure and derivatized resins and the mixtures (maniladiol and breine; alpha and beta-amyrin) were analyzed by TG and DSC. The TG curves revealed that the derivatization decreases the thermal stability of the resin. The DSC curves showed peaks that can be assigned to evaporation and phase transitions processes.

Avaliação por SAXS e DSC das interações entre H2O e Renex-100

The aggregation behavior of the non-ionic surfactant Renex-100 in aqueous solutions and mesophases was evaluated by SAXS in a wide range of concentrations, between 20 and 30 °C. Complementary, water interactions were defined by DSC curves around 0°C. SAXS showed that the system undergoes the following phase transitions, from diluted to concentrated aqueous solutions: 1) isotropic solution of Renex aggregates; 2) hexagonal mesophase; 3) lamellar mesophase; and 4) isotropic solution. DSC analysis indicated the presence of interfacial water above 70wt%, which agreed with the segregation of free water to form the structural mesophases observed by SAXS bellow this concentration.

Schistosoma mansoni granuloma in late evolutive phase, in a case of tumoral form in man

INTRODUCTION: Authors describe human schistosomal granuloma in late chronic phase, from the morphological and evolutionary viewpoints. METHODS: The study was based on a histological analysis of two fragments obtained from a surgical biopsy of peritoneum and large intestine of a 42-year-old patient, with a pseudotumoral form mimicking a peritoneal carcinomatosis associated to the schistosomiasis hepatointestinal form. RESULTS: Two hundred and three granulomas were identified in the pseudotumor and 27 in the intestinal biopsy, with similar morphological features, most in the late chronic phase, in fibrotic healing. A new structural classification was suggested for granulomas: zone 1 (internal), 2 (intermediate) and 3 (external). CONCLUSIONS: Regarding granuloma as a whole, we may conclude that fibrosis is likely to be controlled by different and independent mechanisms in the three zones of the granuloma. Lamellar fibrosis in zone 3 seems to be controlled by matrix mesenchymal cells (fibroblasts and myoepithelial cells) and by inflammatory exudate cells (lymphocytes, plasmocytes, neutrophils, eosinophils). Annular fibrosis in zone 2, comprising a dense fibrous connective tissue, with few cells in the advanced phase, would be controlled by epithelioid cells involving zone 1 in recent granulomas. In zone 1, replacing periovular necrosis, an initialy loose and tracery connective neoformation, housing stellate cells or with fusiform nuclei, a dense paucicellular nodular connctive tissue emerges, probably induced by fibroblasts. In several granulomas, one of the zones is missing and granuloma is represented by two of them: Z3 and Z2, Z3 and Z1 or Z2 and Z1 and, ultimately, by a scar.

Some characteristics of hyperreactivity to bacterial lipopolysaccharide induced in mice by Trypanosoma cruzi infection

Mice infected with T. cruzi strain, acquire a high level of susceptibility to the effects of bacterial gram-negative LPS. The LD50 of adult female SW mice to LPS from S. typhosa, decreases from 450 to 2,5 mcg 10-12 days after T. cruzi infection. This hyperreactivity to LPS induced by T. cruzi presents all the characteristics of that found in infection caused by many other agents. During the acaute phase of experimental infection with T. cruzi Y strain, mice generally die with a hypovolemic shock very similar to that induced in uninfected animals injected with an adequate dose of bacterial endotoxin. There is evidence for and against the hypothesis that LPS absorbed from the instestinal tract may be involved in the mechanism of death of mice during the acute phase of T. cruzi infection.

Development of Eosinophilia in dogs intradermically inoculated with sand fly saliva and Leishmania (Leishmania) chagasi stationary-phase promastigotes

Salivary glad lysates of the sand fly Lutzomia longipalpis have been shown to enhance the infectivity of Leishmania in mice. As shown herein, the simultaneous inoculation of Leishmania chagasi stationary-phase promastigotes and L. longipalpis salivary gland by the intradermal route in a group of mongrel dogs induced a statistically significant eosinophilia, in relation to dogs inoculated with Leishmania or with salivary gland lysate only. These dogs had no evidence of infection, in spite of the infectivity of the promastigotes when inoculated by the intravenous route.

Inflammatory cutaneous reaction induced by the lectin of Dioclea grandiflora (Mart. )

The lectin from Dioclea grandiflora (Mart.) that selectively binds glucose and mannose, when subcutaneously injected in mouse induces an inflammatory cutaneous reaction whose histological analysis reveals an hemorrhagic ulceration with exudative reaction accompanied by an influx of polymorphonuclear leukocytes and giant cells. The presence of lymphocytes and plasma cells in the lesion was insignificant. In order to characterize the in vivo action of inflammatory factors generated by this lesion, distinct lines of mice were used: high and low antibody responder mice; the genetically selected mice to the acute phase of inflammatory reaction; lines of mice deficient in C5, a protein of the complement system. It is shown that the lectin of D. grandiflora acts as an inflammatory agent probably promoting exocytosis and release of mediators.

Induction of synthesis of the rat cystatin S protein by the submandibular gland during the acute phase of experimental Chagas disease

Rats experimentally infected with Trypanosoma cruzi Y strain exhibited hypertrophy of the submandibular gland at 18 days after infection.SDS-PAGE of infected rats saliva revealed the presence of an additional band with an apparent molecular weight of about 13KDa. Electrophoresis of protein salivaand immunochemical analysis with antibody against rat cystatin S confirmed that the protein was identical to that induced by beta adrenergic stimulation.

Recrudescence induced by cyclophosphamide of chronic Trypanosoma cruzi infection in mice is influenced by the parasite strain

Reactivation of chronic chagasic patients may occur upon use of immunosuppressive drugs related to kidney or heart transplantation or when they are affected by concomitant HIV infection. This recrudescence, however, does not occur in all chagasic patients exposed to immunosuppressive agents. We therefore investigated the influence of Trypanosoma cruzi strains in the recrudescence of the parasitism in mice at the chronic phase treated with cyclophosphamide, an immunosuppressor that blocks lymphocytes DNA synthesis and therefore controls B cells response. A large variation was detected in the percentages of newly established acute phases in the groups of mice inoculated with the different strains. We suggest that reactivation of chronic T. cruzi infections is influenced by the parasite intrinsic characteristics, a phenomenon that might occur in the human disease.

Differential expression of adhesion moleculesshaping the T-cell subset prevalence during the early phase of autoimmune and Trypanosoma cruzi-elicited myocarditis

The participation of cell adhesion molecules (CAMs) in the establishment of autoimmune and infectious myocarditis is an important matter of investigation and may have therapeutic implication. Trypanosoma cruzi infection induces a CD8-mediated myocarditis in patients with severe cardiomyopathy and experimental animals. Previously, we have proposed that this predominance of CD8+ T-cells is, at least in part, consequence of the differential expression of CAMs on circulating CD8+ lymphocytes. In the present study we investigated the participation of CAMs in shaping the phenotypic nature of the autoimmune CD4-mediated myosin-induced and the CD8-mediated T. cruzi-elicited myocarditis. We provide evidence that the prevalence of a certain T-cell subset inside the inflamed heart reflects the differential profile of the adhesion molecules VLA-4, LFA-1, and ICAM-1 displayed on a large proportion of this particular T-cell population in peripheral blood during the early phase of inflammation. Further, the expression of VCAM-1, ligand for VLA-4, and ICAM-1, counter-receptor for LFA-1, was up-regulated on vascular endothelium and paralleled the entrance of inflammatory cells into the cardiac tissue. Thus, this up-regulated expression of receptors-counter-receptors that regulate T-cell transmigration through the vascular endothelium may have an important role in the pathogenesis of the early phase of both autoimmune and infectious myocarditis.

Characterization of TcSTI-1, a homologue of stress-induced protein-1, in Trypanosoma cruzi

The life cycle of the protozoan Trypanosoma cruzi exposes it to several environmental stresses in its invertebrate and vertebrate hosts. Stress conditions are involved in parasite differentiation, but little is known about the stress response proteins involved. We report here the first characterization of stress-induced protein-1 (STI-1) in T. cruzi (TcSTI-1). This co-chaperone is produced in response to stress and mediates the formation of a complex between the stress proteins HSP70 and HSP90 in other organisms. Despite the similarity of TcSTI-1 to STI-1 proteins in other organisms, its expression profile in response to various stress conditions, such as heat shock, acidic pH or nutrient starvation, is quite different. Neither polysomal mRNA nor protein levels changed in exponentially growing epimastigotes cultured under any of the stress conditions studied. Increased levels of TcSTI-1 were observed in epimastigotes subjected to nutritional stress in the late growth phase. Co-immunoprecipitation assays revealed an association between TcSTI-1 and TcHSP70 in T. cruzi epimastigotes. Immunolocalization demonstrated that TcSTI-1 was distributed throughout the cytoplasm and there was some colocalization of TcSTI-1 and TcHSP70 around the nucleus. Thus, TcSTI-1 associates with TcHSP70 and TcSTI-1 expression is induced when the parasites are subjected to stress conditions during specific growth phase.

Freund's adjuvant-induced inflammation: clinical findings and its effect on hepcidin mRNA expression in horses

Hypoferremia observed during systemic inflammatory disorders is regulated by hepcidin. Hepcidin up-regulation is particularly important during acute inflammation, as it restricts the availability of iron, which is necessary for pathogenic microorganism growth before adaptive immunity occurs. The aim of this study was to evaluate the clinical findings and hepatic hepcidin mRNA expression in horses using a Freund's complete adjuvant (FCA) model of inflammation. The expression of hepcidin mRNA in the liver was determined in healthy horses following two intramuscular injections of FCA at 0 h and 12 h. Plasma iron and fibrinogen concentrations were measured at multiple time points between 0 h and 240 h post-FCA injection (PI). Hepcidin mRNA expression was determined by RT-qPCR using liver biopsy samples performed at 0 h (control), 6 h and 18 h PI. The mean plasma fibrinogen level was significantly different from the control values only between 120 and 216 h PI. The mean plasma iron level was significantly lower than the control between 16 and 72 h PI, reaching the lowest levels at 30 h PI (33 % of the initial value), and returned to the reference value from 96 h PI to the end of the experiment. Hepcidin mRNA expression increased at 6 h PI and remained high at 18 h PI. The iron plasma concentration was an earlier indicator of inflammatory processes in horses when compared with fibrinogen and might be useful for the early detection of inflammation in the horse. FCA administration caused the rapid onset of hypoferremia, and this effect was likely the result of up-regulated hepatic hepcidin gene expression. This study emphasizes the importance of hepcidin and iron metabolism during inflammation in horses.

Bubble-Bubble Interaction in Horizontal Two-Phase Slug Flow

Modelling of the slug structure requires a new effort on fundamental research. To clarify some aspects of the horizontal slug flow, an experimental study of the behaviour of two isolated bubbles in a single-phase liquid flow was performed. This procedure was adopted to avoid the overlap of different phenomena induced by a train of long bubbles. The experimental facility consists of a 90-m horizontal PVC pipe with internal diameter of 0,053 m. The behaviour of two single air bubbles travelling in a water flow was studied. Focus was given on the influence of the distance between the bubbles on the velocity of the second bubble. This study allows the understanding of the mechanism of overtaking that takes place right after the slug formation and that precedes the coalescence of bubbles in a slug flow. The results show that bubbles placed behind a liquid slug smaller than a critical value move faster than the leading one. Otherwise, they move slower than the leading one.