Synthesis and antibacterial activity of conjugates between norfloxacin and analogues of the siderophore vanchrobactin

From synthetic functionalized analogues of vanchrobactin, a siderophore produced by the fish pathogenic bacteria Vibrio anguillarum serotype O2, several vanchrobactin analogues–norfloxacin conjugates were obtained and their antimicrobial activities against the wild-type and mutant strains of Vibrio anguillarum serotype O2 have been determined.     

Disproportionation of rosin on an industrial Pd/C catalyst: reaction pathway and kinetic model discrimination

In this work, a phenomenological study of the isomerisation and disproportionation of rosin acids using an industrial 5% Pd on charcoal catalyst from 200 to 240°C is carried out. Medium composition is determined by elemental microanalysis, GC-MS and GC-FID. Dehydrogenated and hydrogenated acid species molar amounts in the final product show that dehydrogenation is the main reaction. Moreover, both hydrogen and non-hydrogen concentration considering kinetic models are fitted to experimental data using a multivariable non-linear technique. Statistical discrimination among the proposed kinetic models lead to the conclusion hydrogen considering models fit much better to experimental results. The final kinetic model involves first-order isomerisation reactions of neoabietic and palustric acids to abietic acid, first-order dehydrogenation and hydrogenation of this latter acid, and hydrogenation of pimaric acids. Hydrogenation reactions are partial first-order regarding the acid and hydrogen.     

Benthic macroinfaunal assemblages associated with Amazonian saltmarshes

The composition and abundance of the poorly known benthic macroinfauna associated with northern Brazilian saltmarshes, were described from eight sites (between 0°42′2.5″S, 47°52′44.1″W and 0°50′17.3″S, 46°36′13.3″W) along the Pará coast, Brazil. Sampling was carried out in November of 2007. Univariate and multivariate analyses were used to test for differences in sediment, vegetation and macroinfaunal variables among sites. No vertical zonation of the macroinfauna was detected. Macroinfaunal structure differed greatly among sites with different sediment and vegetation characteristics. Number of individuals and taxa were low in sites with sandy sediments and short, sparse vegetation and high in those with silty sediments with high organic matter and water contents, and tall, dense vegetation. Increasing number of individuals and taxa were associated with a geographical gradient in pore water salinity, which increases from west to east, coinciding with patterns of rainfall described for the Pará coast.     

Marine sediments from southeastern Brazilian continental shelf: A 1200 year record of upwelling productivity

A sediment core from the Cabo Frio coastal shelf (?23.19 S, ?41.8 W; 117 m depth), was analyzed for TOC, C/N ratio, organic petrography and planktonic foraminiferal content to evaluate variations in local productivity caused by changes in upwelling intensity and its relation to regional and global climatic variations during the last millennium. The Cabo Frio core recorded the last 1200 years of sedimentation, with rates varying from 0.11 to 0.32 mm yr^?1. Foraminiferal and organic geochemical analyses indicate the occurrence of three distinct periods of productivity. From 850 AD until 1070 AD, foraminifera fluxes consisting primarily of Turborotalita quinqueloba indicate stronger South Atlantic Central Water (SACW) transport onto the shelf, which induced high biological productivity that was also recorded by high TOC and marine palynomorphs content and a low C/N atomic ratio. This period coincided with a northward displacement of the atmospheric Intertropical Convergence Zone (ITCZ) and South Atlantic High (SAH) systems driven by positive temperature anomalies in the North Atlantic Ocean during the Medieval Climate Anomaly (MCA). From 1070 until 1500 AD, low TOC flux and planktonic foraminifera fluxes and high C/N atomic ratios suggest a reduction in marine productivity, probably driven by reduced transport of SACW associated with the southward displacement of the SAH and weakening of northeasterly winds. The period between 1500 and 1830 AD, which corresponds to the Little Ice Age, is marked by increased fluxes of planktonic foraminifera, principally of Globigerina bulloides and Globigerinita glutinata. These species mark an increase in productivity linked to SACW upwelling, supported by the enhancement of northeasterly winds and southward displacement of the ITCZ and SAH.     

Cellular spelunking: exploring adipocyte caveolae

It has been known for decades that the adipocyte cell surface is particularly rich in small invaginations we now know to be caveolae. These structures are common to many cell types but are not ubiquitous. They have generated considerable curiosity, as manifested by the numerous publications on the topic that describe various, sometimes contradictory, caveolae functions. Here, we review the field from an "adipocentric" point of view and suggest that caveolae may have a function of particular use for the fat cell, namely the modulation of fatty acid flux across the plasma membrane. Other functions for adipocyte caveolae that have been postulated include participation in signal transduction and membrane trafficking pathways, and it will require further experimental scrutiny to resolve controversies surrounding these possible activities.     

Insulin-loaded alginate microspheres for oral delivery – Effect of polysaccharide reinforcement on physicochemical properties and release profile

Oral administration of insulin requires protein protection from degradation in the gastric environment and its absorption improvement in the intestinal tract. To achieve this objective several types of microspheres composed of alginate, chitosan and dextran sulphate have been prepared by ionotropic gelation. Parameters such as the mean particle size, swelling behaviour, insulin encapsulation efficiency, loading capacity and release profiles in simulated gastric and intestinal fluids have been compared for the systems developed. In this study, attempts have been made to increase insulin protection and to improve its release from microspheres by reinforcing the alginate matrix with chitosan and/or dextran sulphate. Dextran sulphate was able to avoid insulin release at pH 1.2, protecting the protein from the acidic environment and reducing the total insulin released at pH 6.8. This effect was explained by an interaction between the permanent negatively charged groups of dextran sulphate and insulin molecules.     

Chemical modulation of VLA integrin affinity in human breast cancer cells

The fact that disruption of integrin-extracellular matrix contacts leads to cell death, has converted cell adhesion into a potential target for the control of invasive cancer. In this work, we studied the functional consequences of the interference with the activity of the very late activation antigen (VLA) family of integrins in human breast cancer cell lines of distinct malignancy. The alpha2beta1-mediated adhesion reduced the entry of highly malignant, hormone-independent breast cancer cells into apoptosis. Adhesion of breast cancer cells through the VLA integrins alpha2beta1 and alpha5beta1 was significantly reduced by an apoptosis-inducing natural triterpenoid, dehydrothyrsiferol (DT), when studied on low amounts of extracellular matrix. This effect was dose-dependent, not related to cell toxicity and not shared with apoptosis-inducing standard chemotherapeutics, such as doxorubicin and taxol. The compound did not affect either the cell surface expression level of VLA integrins or cell distribution of vinculin and actin during cell spreading. In addition, neither phosphorylation of the focal adhesion kinase pp125FAK on Tyr397 nor the protein kinase B (Akt/PKB) on Ser473 was significantly altered by DT. The integrin activation level, assessed by binding of soluble collagen to the alpha2beta1 integrin, was reduced upon cell treatment with DT. Importantly, the TS2/16, an anti-beta1 activating monoclonal antibody was able to rescue DT-treated cells from apoptosis. Since the activation state of integrins is increasingly recognized as an essential factor in metastasis formation, findings presented herein reveal that the chemical regulation of integrin affinity may be a potential therapeutic strategy in cancer therapy.     

Nox2 Mediates Skeletal Muscle Insulin Resistance Induced by a High Fat Diet

Inflammation and oxidative stress through the production of reactive oxygen species (ROS) are consistently associated with metabolic syndrome/type 2 diabetes. Although the role of Nox2, a major ROS-generating enzyme, is well described in host defense and inflammation, little is known about its potential role in insulin resistance in skeletal muscle. Insulin resistance induced by a high fat diet was mitigated in Nox2-null mice compared with wild-type mice after 3 or 9 months on the diet. High fat feeding increased Nox2 expression, superoxide production, and impaired insulin signaling in skeletal muscle tissue of wild-type mice but not in Nox2-null mice. Exposure of C2C12 cultured myotubes to either high glucose concentration, palmitate, or H₂O₂ decreases insulin-induced Akt phosphorylation and glucose uptake. Pretreatment with catalase abrogated these effects, indicating a key role for H₂O₂ in mediating insulin resistance. Down-regulation of Nox2 in C2C12 cells by shRNA prevented insulin resistance induced by high glucose or palmitate but not H₂O₂. These data indicate that increased production of ROS in insulin resistance induced by high glucose in skeletal muscle cells is a consequence of Nox2 activation. This is the first report to show that Nox2 is a key mediator of insulin resistance in skeletal muscle.     

Incidence and Risk Factors of Striae Distensae Following Breast Augmentation Surgery: A Cohort Study

Background

The significant increase in the popularity of breast augmentation surgeries has led to an increase in the number and types of complications; among these is the postoperative occurrence of Striae Distensae (SD). The objective of this study was to investigate the incidence of SD and describing its occurrence in association with age, breast implant volume, history of SD, history of pregnancies and breastfeeding, body mass index (BMI), changes in postoperative weight, smoking habits, and use of oral contraceptives.

Methods

A cohort study was conducted and the patient data from a specific social group that underwent augmentation mammaplasty with silicone breast implants in a private clinic was analyzed.

Results

563 patients entered the cohort, while 538 completed the study. The SD incidence was 7.06%. The risk was almost the double at 22–28 years of age and triple in women of 21 years of age or less. The women who did not use oral contraceptives were 2.59 times more likely of developing SD. A higher incidence of SD was observed among those with normal or low BMI values, smokers, and in those who had implants larger than 300 ml.

Conclusions

Young age, larger implant volumes, smoking, and normal or low BMI values were the risk factors responsible for the development of SD; while using oral contraceptives was found to be a protective factor.