Biosynthesis of magnetic iron oxide nanoparticles: a review.

Nanoparticles promise to revolutionize the way we think of ordinary materials thanks to the new features such small structures exhibit which include strength, durability, optical and magnetics properties. Magnetic iron oxide nanoparticles (IONPs) are a prominent class of NMs because of their potential application in magnetic separation, hyperthermia, targeted drug delivery, and catalysis. Most synthetic nanoparticulate platforms rely on the use of tough chemical procedures associated with unfriendly, harmful and costly reactants. For this reason, bio-inspired approaches have become the most successful alternatives to fabricate nanomaterials in an "eco-friendly" manner, and many bio-protocols that make use of substrates from plants and microorganisms have been successfully applied in the synthesis of magnetic IONPs. In this review, the main biosynthesis protocols applied in the synthesis of iron oxide nanoparticles are discussed. A discussion on the challenges for a second stage perspective which would be a large scale production is also given.

Short-term results (1 year) of vented versus solid polyetheretherketone anchors in treatment of rotator cuff tears.

BACKGROUND: Due to the rotator cuff retear after being surgically repaired, some strategies have been developed. The authors verified that the possibility of polyetheretherketone (PEEK) vented anchors promoted a better clinical and healing process than PEEK solid anchors. METHODS: A prospective and randomized study was designed with 38 patients treated with PEEK anchors, 18 of whom with vented anchors and 20 with solid ones. Demographic, clinical and radiologic data were collected before and during surgery (time 0) and at 12 months of follow-up. RESULTS: In the final follow-up (12 months), there was no difference in the visual analogic scale (VAS) scale between groups (1.7 points vs 1.9 points; p = 0.731), neither in the DASH score (34.2 points vs 23.9 points; p = 0.268), nor in absolute Constant score (76.9 points vs 77.3 points; p = 0.910). In MRI, 10 patients had their cuff tear healed in the vented group and 15 in the solid group (p = 0.173). CONCLUSION: The new designed vented anchors do not add any advantage when compared to solids ones, at least within the first year after surgery.

Sulfonated graphene oxide as effective catalyst for conversion of 5-(hydroxymethyl)-2-furfural into biofuels.

The acid-catalyzed reaction of 5-(hydroxymethyl)-2-furfural with ethanol is a promising route to produce biofuels or fuel additives within the carbohydrate platform; specifically, this reaction may give 5-ethoxymethylfurfural, 5-(ethoxymethyl)furfural diethylacetal, and/or ethyl levulinate (bioEs). It is shown that sulfonated, partially reduced graphene oxide (S-RGO) exhibits a more superior catalytic performance for the production of bioEs than several other acid catalysts, which include sulfonated carbons and the commercial acid resin Amberlyst-15, which has a much higher sulfonic acid content and stronger acidity. This was attributed to the cooperative effects of the sulfonic acid groups and other types of acid sites (e.g., carboxylic acids), and to the enhanced accessibility to the active sites as a result of the 2D structure. Moreover, the acidic functionalities bonded to the S-RGO surface were more stable under the catalytic reaction conditions than those of the other solids tested, which allowed its efficient reuse.

Synthesis and bioactivity of nobilamide B.

An alternative and facile solution/solid-phase approach is reported for the total synthesis of neuroactive peptide, nobilamide B. Z-Dhb was formed in solution via EDC/CuCl induced elimination. The solid-phase synthesis employed HBTU/Oxyma Pure™ coupling using Barlos resin. Synthetic nobilamide B was also found to be neuroactive in primary cultures of dorsal root ganglion (DRG) neurons.

The new automated daily mortality surveillance system in Portugal.

The experience reported in an earlier Eurosurveillance issue on a fast method to evaluate the impact of the 2003 heatwave on mortality in Portugal, generated a daily mortality surveillance system (VDM) that has been operating ever since jointly with the Portuguese Heat Health Watch Warning System. This work describes the VDM system and how it evolved to become an automated system operating year-round, and shows briefly its potential using mortality data from January 2006 to June 2009 collected by the system itself. The new system has important advantages such as: rapid information acquisition, completeness (the entire population is included), lightness (very little information is exchanged, date of death, age, sex, place of death registration). It allows rapid detection of impacts (within five days) and allows a quick preliminary quantification of impacts that usually took several years to be done. These characteristics make this system a powerful tool for public health action. The VDM system also represents an example of inter-institutional cooperation, bringing together organisations from two different ministries, Health and Justice, aiming at improving knowledge about the mortality in the population.

The refined structure of nascent HDL reveals a key functional domain for particle maturation and dysfunction.

The cardioprotective function of high-density lipoprotein (HDL) is largely attributed to its ability to facilitate transport of cholesterol from peripheral tissues to the liver. However, HDL may become dysfunctional through oxidative modification, impairing cellular cholesterol efflux. Here we report a refined molecular model of nascent discoidal HDL, determined using hydrogen-deuterium exchange mass spectrometry. The model reveals two apolipoprotein A1 (apoA1) molecules arranged in an antiparallel double-belt structure, with residues 159-180 of each apoA1 forming a protruding solvent-exposed loop. We further show that this loop, including Tyr166, a preferred target for site-specific oxidative modification within atheroma, directly interacts with and activates lecithin cholesterol acyl transferase. These studies identify previously uncharacterized structural features of apoA1 in discoidal HDL that are crucial for particle maturation, and elucidate a structural and molecular mechanism for generating a dysfunctional form of HDL in atherosclerosis.

Electronic structure, ionization potential, and electron affinity of the enzyme cofactor (6R)-5,6,7,8-tetrahydrobiopterin in the gas phase, solution, and protein environments.

(6R)-5,6,7,8-Tetrahydrobiopterin (BH(4)) is a key cofactor involved in the electron transfer to the P(450) heme of nitric oxide synthase. We calculated the electronic structure of the neutral, cationic, and anionic forms of BH(4) in the gas phase, in solution (both dielectric and explicit water), and in the protein environment using density functional theory (B3LYP/6-31+G(d,p)). Subsequently, we derived the ionization potential (IP) and electron affinity (EA) of the cofactor in these chemical environments. We found that the electronic structure of BH(4) is susceptible to the presence of an external electric field and that conformational changes in the structure of BH(4) alone do not affect its electronic structure significantly. In the gas phase, water, and protein environments neutral BH(4) is the most stable species, while in the dielectric environment the anion becomes the most stable species. The IP of BH(4) in the protein environment is about half of that in the gas phase, and its EA is about 5 times smaller than that in the gas phase. Our results indicate that changes in the external electric field created by moving charged amino acid residues around BH(4) may lead to configurations that have the BH(4) ion as stable as or more stable than the neutral form, thus facilitating the electron transfer.

Myocardial signaling defects and impaired cardiac function of a human beta 2-adrenergic receptor polymorphism expressed in transgenic mice.

A threonine to isoleucine polymorphism at amino acid 164 in the fourth transmembrane spanning domain of the beta 2-adrenergic receptor (beta 2AR) is known to occur in the human population. The functional consequences of this polymorphism to catecholamine signaling in relevant cells or to end-organ responsiveness, however, are not known. To explore potential differences between the two receptors, site-directed mutagenesis was carried out to mimic the polymorphism. Transgenic FVB/N mice were then created overexpressing wild-type (wt) beta 2AR or the mutant Ile-164 receptor in a targeted manner in the heart using a murine alpha myosin heavy chain promoter. The functional properties of the two receptors were then assessed at the level of in vitro cardiac myocyte signaling and in vivo cardiac responses in intact animals. The expression levels of these receptors in the two lines chosen for study were approximately 1200 fmol/mg protein in cardiac membranes, which represents a approximately 45-fold increase in expression over endogenous beta AR. Myocyte membrane adenylyl cyclase activity in the basal state was significantly lower in the Ile-164 mice (19.5 +/- 2.7 pmol/min/mg) compared with wt beta 2AR mice (35.0 +/- 4.1 pmol/min/mg), as was the maximal isoproterenol-stimulated activity (49.8 +/- 7.8 versus 77.1 +/ 7.3 pmol/min/mg). In intact animals, resting heart rate (441 +/- 21 versus 534 +/- 17 bpm) and dP/dtmax (10,923 +/- 730 versus 15,308 +/- 471 mmHg/sec) were less in the Ile-164 mice as compared with wt beta 2AR mice. Similarly, the physiologic responses to infused isoproterenol were notably less in the mutant expressing mice. Indeed, these values, as well as other contractile parameters, were indistinguishable between Ile-164 mice and nontransgenic littermates. Taken together, these results demonstrate that the Ile-164 polymorphism is substantially dysfunctional in a relevant target tissue, as indicated by depressed receptor coupling to adenylyl cyclase in myocardial membranes and impaired receptor mediated cardiac function in vivo. Under normal homeostatic conditions or in circumstances where sympathetic responses are compromised due to diseased states, such as heart failure, this impairment may have important pathophysiologic consequences.

The palmitoylated cysteine of the cytoplasmic tail of alpha 2A-adrenergic receptors confers subtype-specific agonist-promoted downregulation.

Most guanine nucleotide binding protein (G protein)-coupled receptors have a conserved cysteine in the C-terminal cytoplasmic tail near the seventh transmembrane spanning region. This cysteine is known to be palmitoylated in rhodopsin, the beta 2-adrenergic receptor (beta 2AR) and the alpha 2A-adrenergic receptor (alpha 2AAR). For the beta 2AR, this cysteine has been shown to be important for stimulatory G protein (Gs) coupling and agonist-promoted desensitization. For the alpha 2AAR (human alpha 2 C10) palmitoylation occurs at Cys-442, but it is not known what function such fatty acid acylation subserves. The closely related alpha 2CAR subtype denoted alpha 2C4 lacks a cysteine in this region and has different G-protein-coupling characteristics and agonist regulatory properties as compared to alpha 2C10. To assess the role of the palmitoylcysteine in alpha 2AR function, we constructed a mutated alpha 2C10 having a phenylalanine (the analogous amino acid in the alpha 2C4 in this position) substituted for Cys-442, denoted alpha 2C10(Phe-442), and expressed this along with wild-type alpha 2C10 and alpha 2C4 in CHO cells. Functional coupling to inhibitory G protein (Gi) and to Gs was identical between wild-type alpha 2C10 and alpha 2C10(Phe-442). Agonist-promoted desensitization of both the Gi and Gs-mediated pathways was also found to be unaffected by this mutation. Cellular trafficking induced by agonist exposure was evaluated by delineation of intracellular (sequestered) versus cell surface receptors and by determination of net receptor loss. Mutation of Cys-442 did not alter the extent or rate of agonist-promoted sequestration induced by agonists or the recovery from sequestration. However, the downregulation of receptor number after prolonged agonist exposure was completely abolished by this mutation and converted alpha 2C10 to an alpha 2C4 phenotype in regard to this adaptive response. Another mutated alpha 2C10, in which Cys-442 was replaced by alanine, also failed to downregulate. Thus, the function of this cytoplasmic palmitoylcysteine is distinctly different between the alpha 2AR and other G-protein-coupled receptors such as the beta 2AR and rhodopsin, and this suggests that this molecular attribute may subserve diverse roles among members of this family of receptors. For the alpha 2ARs, this may represent an evolved feature that provides for differing needs for regulation of the alpha 2C10 and alpha 2C4 subtypes by agonist.

Contribution of ligand structure to activation of alpha 2-adrenergic receptor subtype coupling to Gs.

Recently, we have demonstrated that alpha 2-adrenergic receptors (alpha 2AR) functionally couple not only to Gi but also to Gs. This alpha 2AR-Gs coupling was subtype selective, in that the degree of alpha 2AR-Gs (but not -Gi) coupling was different between alpha 2AR subtypes. It is not known whether the determinants of this subtype selectively are found within the ligand-binding region of the receptor or within the intracellular G protein-coupling domains of the individual subtypes. We therefore expressed the three cloned human alpha 2AR (alpha 2C10, alpha 2C4, and alpha 2C2) in Chinese hamster ovary cells and studied the contribution of the ligand-binding domain to functional Gi versus Gs coupling, by determining the ability of various agonists (catecholamines, imidazolines, and azepines) to elicit alpha 2AR-mediated inhibition and stimulation of adenylyl cyclase activity. Isolation of Gi and Gs responses was accomplished by incubating cells with cholera or pertussis toxin, respectively. Although each compound was found to be a full agonist for alpha 2AR-Gi coupling, the efficacy of these agonists to elicit alpha 2AR-Gs coupling was markedly different, not only among drugs but also among the three alpha 2AR subtypes. The most notable differences occurred with the imidazoline agonists. Specifically, oxymetazoline stimulated adenylyl cyclase activity 210 +/- 17% for alpha 2C2 and 22 +/- 2.6% for alpha 2C10 and displayed no stimulation for alpha 2C4. UK-14304 stimulated adenylyl cyclase activity 240 +/- 16% for alpha 2C10, 160 +/- 14% for alpha 2C4, and 86 +/- 9% for alpha 2C2. Overall, the rank order of efficacy of these agonists to elicit stimulation of adenylyl cyclase activity by alpha 2C10 was epinephrine = norepinephrine = UK-14304 > BHT-933 > BHT-920 > oxymetazoline. For alpha 2C4 the rank was epinephrine = norepinephrine = UK-14304, with oxymetazoline, BHT-920, and BHT-933 not eliciting any stimulation. For alpha 2C2 the rank was epinephrine = norepinephrine > oxymetazoline > UK-14304 = BHT-920 > BHT-933. Thus, the coupling of alpha 2AR subtypes to Gs occurs with endogenous catecholamines as well as multiple synthetic agonists, and the degree of Gs coupling is highly dependent on the structure of the agonist. Also, compounds that act as full agonists for Gi coupling are not necessarily full agonists for Gs coupling.

A polymorphism of the human beta 2-adrenergic receptor within the fourth transmembrane domain alters ligand binding and functional properties of the receptor.

We have recently identified several naturally occurring variants of the human beta 2-adrenergic receptor (beta 2AR). One of these polymorphisms, which is relatively uncommon, is a mutation occurring in the fourth transmembrane spanning domain, with Ile substituted for Thr at amino acid 164 within the proposed ligand binding pocket. This mutation is adjacent to Ser165 which has been predicted to interact with the beta-carbon hydroxyl group of adrenergic ligands. To determine the functional significance of this variant, we constructed by site-directed techniques a mutated beta 2AR (Ile164) with this substitution and expressed it in CHW-1102 cells. In the presence of guanine nucleotide, Ile164 displayed a lower binding affinity for epinephrine as compared with the wild-type beta 2AR (Ki = 1450 +/- 79 versus 368 +/- 39 nM; p < 0.001). A similarly decreased affinity was found with the catecholamines isoproterenol and norepinephrine, but not with dobutamine or dopamine which lack hydroxyl groups on their beta-carbons. In addition, antagonists without aromatic ring polar substituents displayed a decreased affinity for the mutated receptor. In agonist competition experiments conducted in the absence of guanine nucleotide, Ile164 failed to exhibit detectable high affinity binding, suggesting an impairment in the formation of the agonist-receptor-Gs complex. Consistent with this finding, functional coupling to Gs as determined in adenylyl cyclase assays was significantly (approximately 50%) depressed with Ile164 under both basal and agonist-stimulated conditions. beta 2AR sequestration, which is also triggered by agonist binding, was also found to be approximately 65% reduced in the Ile164 polymorphism. This study represents the first characterization of a naturally occurring mutation of a human adrenergic receptor. Our findings generally support the hypothesized role of this region of the receptor for ligand binding and receptor activation, as well as for establishing critical interactions for overall receptor conformation.

Determinação simultânea dos ácidos hipúrico e metil-hipúrico urinários por métodos cromatográficos: comparação entre cromatografia líquida de alta eficiência e cromatografia gasosa capilar

O presente trabalho foi realizado objetivando-se comparar a eficiência de dois métodos analíticos, um por cromatografia líquida de alta eficiência (CLAE) e outro por cromatografia em fase gasosa com coluna capilar (CG), na determinação conjunta do ácido hipúrico (AH) e ácido metil-hipúrico (AMH) em urina de indivíduos expostos ocupacionalmente ao tolueno e xileno. Após a validação analítica foi observado que o método CLAE apresentou melhores precisão intra e interensaio, porcentagem de recuperação e sensibilidade. Amostras de urina de trabalhadores expostos aos dois solventes em fábrica de tintas-látex foram analisadas pelos dois métodos validados e os resultados avaliados estatisticamente. Não se encontrou diferença significativa entre os valores de AH superiores a 1,0 g/g de creatinina, quando determinados pelos dois métodos cromatográficos. Esta similaridade não foi repetida quando os níveis de AH eram inferiores a 1,0 g/g de creatinina. Os valores de AMH nas amostras analisadas estavam, na maioria das vezes, abaixo do limite de deteção, razão pela qual não foi realizada a comparação estatística entre os mesmos. Arquivo disponível para leitura/ou download nos ícones ao lado.