Sterilization of allograft bone: is 25 kGy the gold standard for gamma irradiation?

For several decades, a dose of 25 kGy of gamma irradiation has been recommended for terminal sterilization of medical products, including bone allografts. Practically, the application of a given gamma dose varies from tissue bank to tissue bank. While many banks use 25 kGy, some have adopted a higher dose, while some choose lower doses, and others do not use irradiation for terminal sterilization. A revolution in quality control in the tissue banking industry has occurred in line with development of quality assurance standards. These have resulted in significant reductions in the risk of contamination by microorganisms of final graft products. In light of these developments, there is sufficient rationale to re-establish a new standard dose, sufficient enough to sterilize allograft bone, while minimizing the adverse effects of gamma radiation on tissue properties. Using valid modifications, several authors have applied ISO standards to establish a radiation dose for bone allografts that is specific to systems employed in bone banking. These standards, and their verification, suggest that the actual dose could be significantly reduced from 25 kGy, while maintaining a valid sterility assurance level (SAL) of 10−6. The current paper reviews the methods that have been used to develop radiation doses for terminal sterilization of medical products, and the current trend for selection of a specific dose for tissue banks.

Efeito da força iônica nas propriedades de fluidos de perfuração aquosos à base de polímeros carboxilados e sulfatados

In the well drilling operations problems caused by contamination of the drilling fluid are common. The dissolution of ions from the geological formations affects the rheological and filtration properties of the fluids. These ions shield the charges of ionic polymers, leading to its precipitation. In this work was performed a detailed study on the stability of the properties of aqueous solutions and aqueous drilling fluids in the presence of sulphated and carboxylated polymers, using carboxymethylcellulose and kappa-carrageenan as polymer compounds carboxylated and sulfated model, respectively. The effects of ionic strength of the aqueous medium containing Na+, Mg2+ and Ca2+ on rheological properties of the polymer and drilling fluids solutions were evaluated by varying the concentration of salts, pH and temperature. It was observed that the fluids with κ-carrageenan suffered less influence against the contamination by the ions at pH 9 to 10, even at higher concentrations, but higher influence on pH> 11. The fluids containing carboxymethylcellulose were more sensitive to contamination, with rapid reduction in viscosity and significant increase of the filtrate volume, while the fluid based polymer sulfated kappa-carrageenan showed evidence of interaction with cations and preserve the rheological properties and improved stability the volume of filtrate.

Efeito da força iônica nas propriedades de fluidos de perfuração aquosos à base de polímeros carboxilados e sulfatados

In the well drilling operations problems caused by contamination of the drilling fluid are common. The dissolution of ions from the geological formations affects the rheological and filtration properties of the fluids. These ions shield the charges of ionic polymers, leading to its precipitation. In this work was performed a detailed study on the stability of the properties of aqueous solutions and aqueous drilling fluids in the presence of sulphated and carboxylated polymers, using carboxymethylcellulose and kappa-carrageenan as polymer compounds carboxylated and sulfated model, respectively. The effects of ionic strength of the aqueous medium containing Na+, Mg2+ and Ca2+ on rheological properties of the polymer and drilling fluids solutions were evaluated by varying the concentration of salts, pH and temperature. It was observed that the fluids with κ-carrageenan suffered less influence against the contamination by the ions at pH 9 to 10, even at higher concentrations, but higher influence on pH> 11. The fluids containing carboxymethylcellulose were more sensitive to contamination, with rapid reduction in viscosity and significant increase of the filtrate volume, while the fluid based polymer sulfated kappa-carrageenan showed evidence of interaction with cations and preserve the rheological properties and improved stability the volume of filtrate.

A model for the time-order error in contrast discrimination.

Trials in a temporal two-interval forced-choice discrimination experiment consist of two sequential intervals presenting stimuli that differ from one another as to magnitude along some continuum. The observer must report in which interval the stimulus had a larger magnitude. The standard difference model from signal detection theory analyses poses that order of presentation should not affect the results of the comparison, something known as the balance condition (J.-C. Falmagne, 1985, in Elements of Psychophysical Theory). But empirical data prove otherwise and consistently reveal what Fechner (1860/1966, in Elements of Psychophysics) called time-order errors, whereby the magnitude of the stimulus presented in one of the intervals is systematically underestimated relative to the other. Here we discuss sensory factors (temporary desensitization) and procedural glitches (short interstimulus or intertrial intervals and response bias) that might explain the time-order error, and we derive a formal model indicating how these factors make observed performance vary with presentation order despite a single underlying mechanism. Experimental results are also presented illustrating the conventional failure of the balance condition and testing the hypothesis that time-order errors result from contamination by the factors included in the model.

Spitzer's contribution to the AGN population

Infrared selection is a potentially powerful way to identify heavily obscured AGNs missed in even the deepest X-ray surveys. Using a 24 μm-selected sample in GOODS-S, we test the reliability and completeness of three infrared AGN selection methods: (1) IRAC color-color selection, (2) IRAC power-law selection, and (3) IR-excess selection; we also evaluate a number of IR-excess approaches. We find that the vast majority of non-power-law IRAC color-selected AGN candidates in GOODS-S have colors consistent with those of star-forming galaxies. Contamination by star-forming galaxies is most prevalent at low 24 μm flux densities (~100 μJy) and high redshifts (z ~ 2), but the fraction of potential contaminants is still high (~50%) at 500 μJy, the highest flux density probed reliably by our survey. AGN candidates selected via a simple, physically motivated power-law criterion ("power-law galaxies," or PLGs), however, appear to be reliable. We confirm that the IR-excess methods successfully identify a number of AGNs, but we also find that such samples may be significantly contaminated by star-forming galaxies. Adding only the secure Spitzer-selected PLG, color-selected, IR-excess, and radio/IR-selected AGN candidates to the deepest X-ray-selected AGN samples directly increases the number of known X-ray AGNs (84) by 54%-77%, and implies an increase to the number of 24 μm-detected AGNs of 71%-94%. Finally, we show that the fraction of MIR sources dominated by an AGN decreases with decreasing MIR flux density, but only down to f_24 μ m = 300 μJy. Below this limit, the AGN fraction levels out, indicating that a nonnegligible fraction (~10%) of faint 24 μm sources (the majority of which are missed in the X-ray) are powered not by star formation, but by the central engine. The fraction of all AGNs (regardless of their MIR properties) exceeds 15% at all 24 μm flux densities.

Spitzer power-law active galactic nucleus candidates in the chandra deep field-north

We define a sample of 62 galaxies in the Chandra Deep Field-North whose Spitzer IRAC SEDs exhibit the characteristic power-law emission expected of luminous AGNs. We study the multiwavelength properties of this sample and compare the AGNs selected in this way to those selected via other Spitzer color-color criteria. Only 55% of the power-law galaxies are detected in the X-ray catalog at exposures of >0.5 Ms, although a search for faint emission results in the detection of 85% of the power-law galaxies at the ≥2.5 σ detection level. Most of the remaining galaxies are likely to host AGNs that are heavily obscured in the X-ray. Because the power-law selection requires the AGNs to be energetically dominant in the near- and mid-infrared, the power-law galaxies comprise a significant fraction of the Spitzer-detected AGN population at high luminosities and redshifts. The high 24 μm detection fraction also points to a luminous population. The power-law galaxies comprise a subset of color-selected AGN candidates. A comparison with various mid-infrared color selection criteria demonstrates that while the color-selected samples contain a larger fraction of the X-ray-luminous AGNs, there is evidence that these selection techniques also suffer from a higher degree of contamination by star-forming galaxies in the deepest exposures. Considering only those power-law galaxies detected in the X-ray catalog, we derive an obscured fraction of 68% (2 : 1). Including all of the power-law galaxies suggests an obscured fraction of <81% (4 : 1).

Semi-parametric geolocation estimation in NLOS environments

The position of a stationary target can be determined using triangulation in combination with time of arrival measurements at several sensors. In urban environments, none-line-of-sight (NLOS) propagation leads to biased time estimation and thus to inaccurate position estimates. Here, a semi-parametric approach is proposed to mitigate the effects of NLOS propagation. The degree of contamination by NLOS components in the observations, which result in asymmetric noise statistics, is determined and incorporated into the estimator. The proposed method is adequate for environments where the NLOS error plays a dominant role and outperforms previous approaches that assume a symmetric noise statistic.

Basalt analyses from different DSDP Holes in the Mozambique Basin and Ridge and from the Southwest Indian Ridge

Basalts from DSDP Sites 248, 249, 250 and 251 in the southwestern Indian Ocean formed in a complex tectonic region affected by the separation of Africa and South America. The different ages and variable geochemical features of these DSDP basalts probably reflect this tectonic complexity. For example, Site 251 on the flanks of the Southwest Indian Ridge is represented by normal MORB which probably originated at the Southwest Indian Ridge. Site 250 in the Mozambique Basin includes an older incompatible- element enriched unit which may represent basalt associated with the Prince Edward Fracture Zone; the upper unit is normal MORB. Basalts at Site 248 also in the Mozambique Basin are geochemically very unlike MORB and have strong continental affinities; they are also comparable in age to some of the continental Karroo basalts. They appear to be related to a subcontinental mantle source or to contamination by continental basement associated with the tectonic elevation of the Mozambique Ridge. Basalts from Site 249 on the Mozambique Ridge are relatively weathered but appear to be normal MORB. Their age, location, and composition are consistent with their origin at an early Cretaceous rift which has been postulated to have separated the Falkland Plateau from the Mozambique Ridge.

Extractions and analyses of reactive phosphorus in the Bering Sea from IODP Holes 323-U1341A and 323-U1341B

To reconstruct the cycling of reactive phosphorus (P) in the Bering Sea, a P speciation record covering the last ~ 4 Ma was generated from sediments recovered during Integrated Ocean Drilling Program (IODP) Expedition 323 at Site U1341 (Bowers Ridge). A chemical extraction procedure distinguishing between different operationally defined P fractions provides new insight into reactive P input, burial and diagenetic transformations. Reactive P mass accumulation rates (MARs) are ~ 20-110 µmol/cm2/ka, which is comparable to other open ocean locations but orders of magnitude lower than most upwelling settings. We find that authigenic carbonate fluorapatite (CFA) and opal-bound P are the dominant P fractions at Site U1341. An overall increasing contribution of CFA to total P with sediment depth is consistent with a gradual "sink switching" from more labile P fractions (fish remains, Fe oxides, organic matter) to stable authigenic CFA. However, the positive correlation of CFA with Al content implies that a significant portion of the supposedly reactive CFA is non-reactive "detrital contamination" by eolian and/or riverine CFA. In contrast to CFA, opal-bound P has rarely been studied in marine sediments. We find for the first time that opal-bound P directly correlates with excess silica contents. This P fraction was apparently available to biosiliceous phytoplankton at the time of sediment deposition and is a long-term sink for reactive P in the ocean, despite the likelihood for diagenetic re-mobilisation of this P at depth (indicated by increasing ratios of excess silica to opal-bound P). Average reactive P MARs at Site U1341 increase by ~ 25% if opal-bound P is accounted for, but decrease by ~ 25% if 50% of the extracted CFA fraction (based on the lowest CFA value at Site U1341) is assumed to be detrital. Combining our results with literature data, we present a qualitative perspective of terrestrial CFA and opal-bound P deposition in the modern ocean. Riverine CFA input has mostly been reported from continental shelves and margins draining P-rich lithologies, while eolian CFA input is found across wide ocean regions underlying the Northern Hemispheric "dust belt". Opal-bound P burial is important in the Southern Ocean, North Pacific, and likely in upwelling areas. Shifts in detrital CFA and opal-bound P deposition across ocean basins likely occurred over time, responding to changing weathering patterns, sea level, and biogenic opal deposition.

Biodegradação de deoxinivalenol por aspergillus oryzae e rhizopus sp.: um estudo bioquímico de degradação e toxicidade

A contaminação aleatória de alimentos por micotoxinas afeta as condições de sanidade das dietas de humanos e animais. Dentre as toxinas fúngicas, deoxinivalenol (DON) se destaca pela freqüente contaminação de produtos agrícolas e alimentos e pela sua resistência a degradação pelo emprego de métodos tradicionais de processamento, o que motiva políticas de controle e a busca por técnicas de descontaminação. A descontaminação biológica empregando processsos fermentativos tem sido apontada como uma alternativa promissora, pois permite degradar micotoxinas através do sistema enzimático microbiano e melhorar características funcionais e sensoriais de matérias-primas e insumos alimentícios. Este trabalho teve por objetivo estudar condições e mecanismos de biodegradação de deoxinivalenol empregando Aspergillus oryzae e Rhizopus sp. em sistemas fermentativos submersos. Para tanto, foi necessário adequar metodologia para reação de derivação na determinação cromatográfica de DON; estudar o potencial e condições de degradação via fermentação submersa por Aspergillus oryzae e Rhizopus sp.; e avaliar a atividade de oxidoredutases e a citotoxicidade dos extratos fementados. A otimização da metodologia estabeleceu a melhor condição para a reação de derivação com 200 µL de anidrido trifluoroacético e 18 mg de bicarbonato de sódio, durante 6 minutos a 74 °C na faixa entre 7 e 21 µg de DON. A quantificação de DON residual no meio fermentado mostrou que as espécies fúngicas Rhizopus sp. e Aspergillus oryzae possuem a capacidade de degradar DON demonstrando índices médios de 87,4 e 62,4% respectivamente, principalmente quando o meio submerso foi água estéril e fermentação realizada durante 48 horas. A velocidade máxima de degradação neste intervalo foi de 10,8 e 12,4 ppb/h, observando também um aumento na atividade específica da enzima peroxidase. Os extratos dos fermentados com A. oryzae e Rhizopus sp. apresentaram efeito de inibição de proliferação celular (IC50) quando concentrados 10 vezes em 48 e 72 horas respectivamente. Os meios fermentados com Rhizopus sp. apresentaram menor efeito (1,5 vezes) quando comparado com Aspergillus oryzae.

Determinação da toxicidade aguda e caracterização de risco ambiental do herbicida Roundup (glifosato) sobre três espécies de peixes

Considering their commercial importance, as these are the species of freshwater fish more commercialized in Brazil, their occurence in different kinds of aquatic environments (lakes, rivers and dams) and for being tolerant to a wide range of variation of various physical parameters and chemical water, the fish species Oreochromis niloticus, Cyprinus carpio and Colossoma macropomum were chosen for this study, furthermore, to test the toxicity we used the herbicide Roundup. The fingerlings of tilapia (Oreochromis niloticus), commun carp (Cyprinus carpio) and tambaqui (Colossoma macropomum) were submitted to the herbicide roundup in the following concentrations: 0.0 (control); 18,06; 19,10; 20,14; 21,18 and 22,22 mg.L-1, 0.0 (control); 13,89; 14,86; 15,83; 16,81 and 17,78 mg.L-1, and 0.0 (control); 18,06; 19,10; 20,14; 21,18 and 22,22 mg.L-1, respectively, three for 96 hours. The LC50 - 96h for O. niloticus, C. carpio and C. macropomum was 21,63, 15,33 and 20,06 mg.L-1 of the herbicide roundup, respectively. The results show that this herbicide is classified as slightly toxic to the three species. The values of dissolved oxygen, pH and temperature recorded in the aquarium control and aquarium experimental of the three fish species have remained without significant variations during the tests, which reduces the possibility of death caused by sudden variations of these parameters during the 96 hours the experiment. The values of LC50 between different species of fish were observed, noting that the species O.niloticus, C. carpio and C. macropomum showed no expressive differences. The values of environmental risk of Roundup were calculated to obtain more stringent parameters in assessing the dangerousness of those on nontargets. The risk of environmental contamination by Roundup for the Nile tilapia, common carp, and tambaqui are low for the lowest application rate (1 L.ha-1) and depths (1.5 and 2.0 m). The dilution of 100%, the highest recommended dose (5 L.ha-1) and depths (1.5 and 2.0 m) the risk is moderate for the three species. The values of the Risk Ratio (QR) were greater than 0,1, indicating that the values of the CAE and LC50 are above acceptable levels and there is a need, this study, a refinement in ecotoxicological tests

Avaliação da ecotoxicidade de percolados em áreas de disposição de resíduos na região metropolitana de Natal/RN

Leachates are effluent produced by decomposition of solid waste, they have complex composition and can be highly toxic. Therefore such percolated liquid should be collected and treated properly to avoid environmental contamination of soil and of water bodies. The objective of this study was to evaluate the toxicity through ecotoxicological tests with Ceriodaphnia dubia (Cladocera - Crustacea) of percolated liquids generated in two different systems of municipal solid waste (MSW) disposal in the city of Natal/ RN: A Sanitary Landfill in the Metropolitan Region of Natal/ RN, and in a dump off area. Furthermore, it was evaluated the possible contamination of the underground water of the dump off area. Two monthly samples were taken at four points between the months of May/2009 and January/2010. The Point "A" corresponds to the end of the pond leachate treatment in ASRMN; The Point "B" corresponds to a containment pond at the dump. The Point "C" is an area near one of the cells of the dump off area where the leachate outcrops; The Point "D" stands for an underground water well at the area. The last point, called "E" was sampled only once and corresponds to the slurry produced by temporary accumulation of solid waste in the open area of the dump. The ecotoxicological tests, acute and chronic, followed the ABNT 13373/2005 rules, with some modifications. The samples were characterized by measuring the pH number, the dissolved oxygen (DO), the salinity, BOD5, COD, Cd, Cu, Pb, Cr, Fe, Mg, Ni, and Zn. At Point A, the average number of EC50-48h ranged between 1.0% and 2.77% (v/v), showing a high toxicity of the leachate to C.dubia in all months. To this point, positive correlations were found between the EC50- 48 with precipitation. Negative correlations were found between the EC50- 48h with salinity. At point B there was no response of the acute exposure of organisms to the test samples. At point C the EC50-48h ranged from 17.68% to 35.36% in just two months of the five ones analyzed, not correlated meaning. Point D, the EC50-48h level ranged between 12.31% and 71.27%, showed a negative correlation with, only, precipitation. Although it was observed toxicity of underground water in the Landfill Area, there was no evidence of water contamination by leachate, however, due to the toxic character of this water, additional tests should be conducted to confirm the quality of water that is used for human supply. At point E there was no acute toxicity. These results support the dangers of inappropriate disposal of MSW to water bodies due to the high toxicity of the leachate produced highlighting the necessity of places of safe confinement and a treatment system more effective to it

Wind Waves in the Arctic Seas: Envisat and AltiKa Data Analysis

Wind-generated waves in the Kara, Laptev, and East-Siberian Seas are investigated using altimeter data from Envisat RA-2 and SARAL-AltiKa. Only isolated ice-free zones had been selected for analysis. Wind seas can be treated as pure wind-generated waves without any contamination by ambient swell. Such zones were identified using ice concentration data from microwave radiometers. Altimeter data, both significant wave height (SWH) and wind speed, for these areas were further obtained for the period 2002-2012 using Envisat RA-2 measurements, and for 2013 using SARAL-AltiKa. Dependencies of dimensionless SWH and wavelength on dimensionless wave generation spatial scale are compared to known empirical dependencies for fetch-limited wind wave development. We further check sensitivity of Ka- and Ku-band and discuss new possibilities that AltiKa's higher resolution can open.

Purificação e caracterização parcial de uma Fucana C de Dictyota mentrualis e estudo do seu efeito antiinflamatório e nociceptivo

In recent years, sulfated polysaccharides from marine algae have emerged as an important class of natural biopolymers with potential application in human and veterinary health care, while taking advantage of the absence of potential risk of contamination by animal viruses. Among these, fucans isolated from the cell walls of marine brown alga have been study due to their anticoagulant, antithrombotic, anti-inflammatory and antiviral activities. These biological effects of fucans have been found to depend on the degree of sulfation and molecular size of the polysaccharide chains. In the present study, we examined structural features of a fucan extracted from brown alga Dictyota menstrualis and its effect on the leukocyte migration to the peritoneum. The sulfated polysaccharides were extracted from the brown seaweed by proteolytic digestion, followed by sequential acetone precipitation producing 5 fractions. Gel lectrophoresis using 0.05 M 1,3-diaminopropane-acetate buffer, pH 9.0, stained with 0.1% toluidine blue, showed the presence of sulfated polysaccharides in all fractions. The chemical analyses demonstrated that all fractions are composed mainly of fucose, xylose, galactose, uronic acid, and sulfate. Electrophoresis in agarose gel in three different buffers demonstrated that the fraction 2.0v have only one population of fucan. This compound was purify by exclusion molecular. It has shown composition of fucose, xilose, sulfate and uronic acid in molar ration of 1.0: 1.7: 1.1: 0.5 respectively. The effect of this heterofucan on the leukocyte migration was observed 6h after zymozan (mg/g) administration into the peritoneum. The heterofucan showed higher antimigratory activity, it decrease the migration of leukocyte in 83.77% to peritoneum. The results suggest that this fucan is a new antimigratory compound with potential pharmacological appications

Atividades biológicas de xilana de sabugo de milho

The corn cob is an agricultural by-product still little used, this in part due to the low knowledge of the biotechnological potential of their molecules. Xylan from corn cobs (XSM) is a polysaccharide present in greater quantity in the structure of plant and its biotechnology potential is little known. This study aimed to the extraction, chemical characterization and evaluation of biological activities of xylan from corn cobs. To this end, corncobs were cleaned, cut, dried and crushed, resulting in flour. This was subjected to a methodology that combines the use of alkaline conditions with waves of ultrasound. After methanol precipitation, centrifugation and drying was obtained a yield of 40% (g/g flour). Chemical analysis indicated a high percentage of polysaccharides in the sample (60%) and low contamination by protein (0.4%) and phenolic compounds (> 0.01%). Analysis of monosaccharide composition indicated the presence of xylose:glucose:arabinose:galactose:mannose:glucuronic acid in a molar ratio 50:20:15:10:2.5:2.5. The presence of xylan in the sample was confirmed by nuclear magnetic resonance (¹H and ¹³C) and infrared spectroscopy (IR). Tests were conducted to evaluate the antioxidant potential of XSM. This showed a total antioxidant capacity of 48.45 EAA/g sample. However, did not show scavenging activity of superoxide and hydroxyl radical and also reducing power. But, showing a high capacity chelating iron ions with 70% with about 2 mg/mL. The ability to XSM to influence cell proliferation in culture was also evaluated. This polymer did not influence the proliferation of normal fibroblast cells (3T3), however, decreased the rate of proliferation of tumor cells (HeLa) in a dose-dependent, reaching an inhibition of about 50% with a concentration around 2 mg/mL. Analyzing proteins related to cell death, by immunoblotting, XSM increases the amount of Bax, Bcl-2 decrease, increase cytochrome c and AIF, and reduce pro-caspase-3, indicating the induction of cell death induced apoptosis dependent and independent of caspase. XSM did not show anticoagulant activity in the PT test. However, the test of activated partial thromboplastin time (aPTT), XSM increased clotting time at about 5 times with 600 μg of sample compared with the negative control. The presence of sulfate on the XSM was discarded by agarose gel electrophoresis and IR. After carboxyl-reduction of XSM the anticoagulant activity decreased dramatically. The data of this study demonstrate that XSM has potential as antioxidant, antiproliferative and anticoagulant compound. Future studies to characterize these activities of XSM will help to increase knowledge about this molecule extracted from corn and allow their use in functional foods, pharmaceuticals and chemical industries.