Stress distribution in bone simulation model with pre-angled implants

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A matheuristic for the selection of beam directions and dose distribution in radiotherapy planning

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Juvenile onset systemic lupus erythematosus: a possible role for vitamin D in disease status and bone health

Purpose: In juvenile onset systemic lupus erythematosus (JoSLE), evidence for the association between vitamin D status, lupus activity, and bone health is very limited and not conclusive. The aim of this study was, therefore, to assess in JoSLE patients the possible relevance of vitamin D deficiency in disease and bone parameters. Methods: Fifty-seven JoSLE patients were initially compared to 37 age, race and body mass index (BMI) -matched healthy controls. The serum concentration of 25 hydroxyvitamin D (25OHD) was determined by radioimmunoassay. Patients with 25OHD deficiency (acurrency sign20 ng/mL) were compared to those with levels > 20 ng/mL. Disease activity was evaluated by SLE Disease Activity Index (SLEDAI). Bone mineral density (BMD) and body composition (BC) were measured using dual-energy X-ray absorptiometry (DXA). Results: 25OHD levels were similar in patients and controls (21.44 +/- 7.91 vs 22.54 +/- 8.25 ng/mL, p = 0.519), regardless of supplementation (65% of patients and none in controls). Thirty-one patients with 25OHD deficiency (acurrency sign20 ng/mL) were further compared to the 26 JoSLE patients with levels > 20 ng/mL. These two groups were well-balanced regarding vitamin D confounding variables: age (p = 0.100), ethnicity (p = 1.000), BMI (p = 0.911), season (p = 0.502), frequency of vitamin D supplementation (p = 0.587), creatinine (p = 0.751), renal involvement (p = 0.597), fat mass (p = 0.764), lean mass (p = 0.549), previous/current use of glucocorticoids(GC) (p = 1.0), immunosuppressors (p = 0.765), and mean current daily dose of GC (p = 0.345). Patients with vitamin D deficiency had higher SLEDAI (3.35 +/- 4.35 vs 1.00 +/- 2.48, p = 0.018), lower C4 levels (12.79 +/- 6.78 vs 18.38 +/- 12.24 mg/dL, p = 0.038), lower spine BMD (0.798 +/- 0.148 vs 0.880 +/- 0.127 g/cm2, p = 0.037) and whole body BMD (0.962 +/- 0.109 vs 1.027 +/- 0.098 g/cm2, p = 0.024). Conclusion: JoSLE vitamin D deficiency, in spite of conventional vitamin D supplementation, affects bone and disease activity status independent of therapy and fat mass reinforcing the recommendation to achieve adequate levels. Lupus (2012) 21, 1335-1342.

Tomotherapy dose distribution verification using MAGIC-f polymer gel dosimetry

Purpose: This paper presents the application of MAGIC-f gel in a three-dimensional dose distribution measurement and its ability to accurately measure the dose distribution from a tomotherapy unit. Methods: A prostate intensity-modulated radiation therapy (IMRT) irradiation was simulated in the gel phantom and the treatment was delivered by a TomoTherapy equipment. Dose distribution was evaluated by the R2 distribution measured in magnetic resonance imaging. Results: A high similarity was found by overlapping of isodoses of the dose distribution measured with the gel and expected by the treatment planning system (TPS). Another analysis was done by comparing the relative absorbed dose profiles in the measured and in the expected dose distributions extracted along indicated lines of the volume and the results were also in agreement. The gamma index analysis was also applied to the data and a high pass rate was achieved (88.4% for analysis using 3%/3 mm and of 96.5% using 4%/4 mm). The real three-dimensional analysis compared the dose-volume histograms measured for the planning volumes and expected by the treatment planning, being the results also in good agreement by the overlapping of the curves. Conclusions: These results show that MAGIC-f gel is a promise for tridimensional dose distribution measurements. (C) 2012 American Association of Physicists in Medicine. [http://dx.doi.org/10.1118/1.4704496]

End-to-end Distance Distribution in Fluorescent Derivatives of Bradykinin in Interaction with Lipid Vesicles

Cellular membranes have relevant roles in processes related to proteases like human kallikreins and cathepsins. As enzyme and substrate may interact with cell membranes and associated co-factors, it is important to take into account the behavior of peptide substrates in the lipid environment. In this paper we report an study based on energy transfer in two bradykinin derived peptides labeled with the donor-acceptor pair Abz/Eddnp (ortho-aminobenzoic acid/N-[2,4-dinitrophenyl]-ethylenediamine). Time-resolved fluorescence experiments were performed in phosphate buffer and in the presence of large unilamelar vesicles of phospholipids, and of micelles of sodium dodecyl sulphate (SDS). The decay kinetics were analyzed using the program CONTIN to obtain end-to-end distance distribution functions f(r). Despite of the large difference in the number of residues the end-to-end distance of the longer peptide (9 amino acid residues) is only 20 % larger than the values obtained for the shorter peptide (5 amino acid residues). The proline residue, in position 4 of the bradykinin sequence promotes a turn in the longer peptide chain, shortening its end-to-end distance. The surfactant SDS has a strong disorganizing effect, substantially broadening the distance distributions, while temperature increase has mild effects in the flexibility of the chains, causing small increase in the distribution width. The interaction with phospholipid vesicles stabilizes more compact conformations, decreasing end-to-end distances in the peptides. Anisotropy experiments showed that rotational diffusion was not severely affected by the interaction with the vesicles, suggesting a location for the peptides in the surface region of the bilayer, a result consistent with small effect of lipid phase transition on the peptides conformations.

Reproductive biology and species geographical distribution in the Melastomataceae: a survey based on New World taxa

Apomictic plants are less dependent on pollinator services and able to occupy more diverse habitats than sexual species. However, such assumptions are based on temperate species, and comparable evaluation for species-rich Neotropical taxa is lacking. In this context, the Melastomataceae is a predominantly Neotropical angiosperm family with many apomictic species, which is common in the Campos Rupestres, endemism-rich vegetation on rocky outcrops in central Brazil. In this study, the breeding system of some Campo Rupestre Melastomataceae was evaluated, and breeding system studies for New World species were surveyed to test the hypothesis that apomixis is associated with wide distributions, whilst sexual species have more restricted areas. The breeding systems of 20 Campo Rupestre Melastomataceae were studied using hand pollinations and pollen-tube growth analysis. In addition, breeding system information was compiled for 124 New World species of Melastomataceae with either wide (1000 km) or restricted distributions. Most (80 ) of the Campo Rupestre species studied were self-compatible. Self-incompatibility in Microlicia viminalis was associated with pollen-tube arrest in the style, as described for other Melastomataceae, but most self-incompatible species analysed showed pollen-tube growth to the ovary irrespective of pollination treatment. Apomictic species showed lower pollen viability and were less frequent among the Campo Rupestre plants. Among the New World species compiled, 43 were apomictic and 77 sexual (24 self-incompatible and 53 self-compatible). Most apomictic (86 ) and self-incompatible species (71 ) presented wide distributions, whilst restricted distributions predominate only among the self-compatible ones (53 ). Self-compatibility and dependence on biotic pollination were characteristic of Campo Rupestre and narrowly distributed New World Melastomataceae species, whilst apomictics are widely distributed. This is, to a certain extent, similar to the geographical parthenogenesis pattern of temperate apomictics.

Finite element analysis of stress distribution in anchor teeth in surgically assisted rapid palatal expansion

The treatment of a transverse maxillary deficiency in skeletally mature individuals should include surgically assisted rapid palatal expansion. This study evaluated the distribution of stresses that affect the expander's anchor teeth using finite element analysis when the osteotomy is varied. Five virtual models were built and the surgically assisted rapid palatal expansion was simulated. Results showed tension on the lingual face of the teeth and alveolar bone, and compression on the buccal side of the alveolar bone. The subtotal Le Fort I osteotomy combined with intermaxillary suture osteotomy seemed to reduce the dissipation of tensions. Therefore, subtotal Le Fort I osteotomy without a step in the zygomaticomaxillary buttress, combined with intermaxillary suture osteotomy and pterygomaxillary disjunction may be the osteotomy of choice to reduce tensions on anchor teeth, which tend to move mesiobuccally (premolar) and distobuccally (molar)

Mapping the lignin distribution in pretreated sugarcane bagasse by confocal and fluorescence lifetime imaging microscopy

Abstract Background Delignification pretreatments of biomass and methods to assess their efficacy are crucial for biomass-to-biofuels research and technology. Here, we applied confocal and fluorescence lifetime imaging microscopy (FLIM) using one- and two-photon excitation to map the lignin distribution within bagasse fibers pretreated with acid and alkali. The evaluated spectra and decay times are correlated with previously calculated lignin fractions. We have also investigated the influence of the pretreatment on the lignin distribution in the cell wall by analyzing the changes in the fluorescence characteristics using two-photon excitation. Eucalyptus fibers were also analyzed for comparison. Results Fluorescence spectra and variations of the decay time correlate well with the delignification yield and the lignin distribution. The decay dependences are considered two-exponential, one with a rapid (τ1) and the other with a slow (τ2) decay time. The fastest decay is associated to concentrated lignin in the bagasse and has a low sensitivity to the treatment. The fluorescence decay time became longer with the increase of the alkali concentration used in the treatment, which corresponds to lignin emission in a less concentrated environment. In addition, the two-photon fluorescence spectrum is very sensitive to lignin content and accumulation in the cell wall, broadening with the acid pretreatment and narrowing with the alkali one. Heterogeneity of the pretreated cell wall was observed. Conclusions Our results reveal lignin domains with different concentration levels. The acid pretreatment caused a disorder in the arrangement of lignin and its accumulation in the external border of the cell wall. The alkali pretreatment efficiently removed lignin from the middle of the bagasse fibers, but was less effective in its removal from their surfaces. Our results evidenced a strong correlation between the decay times of the lignin fluorescence and its distribution within the cell wall. A new variety of lignin fluorescence states were accessed by two-photon excitation, which allowed an even broader, but complementary, optical characterization of lignocellulosic materials. These results suggest that the lignin arrangement in untreated bagasse fiber is based on a well-organized nanoenvironment that favors a very low level of interaction between the molecules.

Red and infrared light distribution in blood.

Low level laser therapy (LLLT) is used in several applications, including the reduction of inflammatory processes. It might be used to prevent the systemic inflammatory response syndrome (SIRS), which some patients develop after cardiopulmonary bypass (CPB) surgery. The objectives of this study were to investigate light distribution inside blood, in order to implement the LLLT during CPB, and, through this study, to determine the best wavelength and the best way to perform the treatment. The blood, diluted to the same conditions of CPB procedure was contained inside a cuvette and an optical fiber was used to collect the scattered light. Two wavelengths were used: 632.8 nm and 820 nm. Light distribution in blood inside CPB tubes was also evaluated. Compared to the 820 nm light, the 632.8 nm light is scattered further away from the laser beam, turning it possible that a bigger volume of blood be treated. The blood should be illuminated through the smallest diameter CPB tube, using at least four distinct points around it, in only one cross section, because the blood is kept passing through the tube all the time and the whole volume will be illuminated.

Natural radionuclides distribution in the shelf and upper slope off southeast Brazil

In recent decades, Oceanography has been using a variety of radionuclides as tracers to understand the ocean dynamic processes, handling and disposal of sediments of seabed. In this context, the determination of natural radionuclides distributions (238U, 232Th and 40K) has been carried out with sediments samples from the shelf and upper slope off Southeast Brazil using a gamma spectrometry technique. The samples were sliced into strata of 2 cm, dried, ground and properly packed to be analysed. The concentration of activities was performed in a hyperpure Ge detector with a resolution of 1,9 keV for the peak of 1332,3 keV of 60Co, model GEM50P by EGG&ORTEC. The study area is located between latitudes 28°40'S and 23°00'S and extends from Cabo Frio (RJ) to Cabo de Santa Marta Grande (SC). The activity concentrations varied from 0,6 to 52,8 BqKg-1 for 238U, from 1,6 to 50,9BqKg-1 for 232Th and from 65,4 to 873,3 BqKg-1 for 40K. From these results it is possible to establish a correlation between the depositional area dynamics and the samples size parameters

Local strain distribution in real three-dimensional alveolar geometries

Mechanical ventilation is not only a life saving treatment but can also cause negative side effects. One of the main complications is inflammation caused by overstretching of the alveolar tissue. Previously, studies investigated either global strains or looked into which states lead to inflammatory reactions in cell cultures. However, the connection between the global deformation, of a tissue strip or the whole organ, and the strains reaching the single cells lining the alveolar walls is unknown and respective studies are still missing. The main reason for this is most likely the complex, sponge-like alveolar geometry, whose three-dimensional details have been unknown until recently. Utilizing synchrotron-based X-ray tomographic microscopy, we were able to generate real and detailed three-dimensional alveolar geometries on which we have performed finite-element simulations. This allowed us to determine, for the first time, a three-dimensional strain state within the alveolar wall. Briefly, precision-cut lung slices, prepared from isolated rat lungs, were scanned and segmented to provide a three-dimensional geometry. This was then discretized using newly developed tetrahedral elements. The main conclusions of this study are that the local strain in the alveolar wall can reach a multiple of the value of the global strain, for our simulations up to four times as high and that thin structures obviously cause hotspots that are especially at risk of overstretching.

Comparison of brain PrPd distribution in ovine BSE and scrapie

Scrapie and bovine spongiform encephalopathy (BSE) are both prion diseases affecting ruminants, and these diseases do not share the same public health concerns. Surveillance of the BSE agent in small ruminants has been a great challenge, and the recent identification of diverse prion diseases in ruminants has led to the development of new methods for strain typing. In our study, using immunohistochemistry (IHC), we assessed the distribution of PrP(d) in the brains of 2 experimentally BSE-infected sheep with the ARQ/ARQ genotype. Distribution of PrP(d) in the brain, from the spinal cord to the frontal cortex, was remarkably similar in the 2 sheep despite different inoculation routes and incubation periods. Comparatively, overall PrP(d) brain distribution, evaluated by IHC, in 19 scrapie cases with the ARQ/ARQ, ARQ/VRQ, and VRQ/VRQ genotypes, in some cases showed similarities to the experimentally BSE-infected sheep. There was no exclusive neuroanatomical site with a characteristic and specific PrP(d) type of accumulation induced by the BSE agent. However, a detailed analysis of the topography, types, and intensity of PrP(d) deposits in the frontal cortex, striatum, piriform cortex, hippocampus, mesencephalon, and cerebellum allowed the BSE-affected sheep group to be distinguished from the 19 scrapie cases analyzed in our study. These results strengthen and emphasize the potential interest of PrP(d) brain mapping to help in identifying prion strains in small ruminants.

The effect of standard and low-modulus cement augmentation on the stiffness, strength, and endplate pressure distribution in vertebroplasty

Vertebroplasty restores stiffness and strength of fractured vertebral bodies, but alters their stress transfer. This unwanted effect may be reduced by using more compliant cements. However, systematic experimental comparison of structural properties between standard and low-modulus augmentation needs to be done. This study investigated how standard and low-modulus cement augmentation affects apparent stiffness, strength, and endplate pressure distribution of vertebral body sections.

Haptics in forensics: the possibilities and advantages in using the haptic device for reconstruction approaches in forensic science

Non-invasive documentation methods such as surface scanning and radiological imaging are gaining in importance in the forensic field. These three-dimensional technologies provide digital 3D data, which are processed and handled in the computer. However, the sense of touch gets lost using the virtual approach. The haptic device enables the use of the sense of touch to handle and feel digital 3D data. The multifunctional application of a haptic device for forensic approaches is evaluated and illustrated in three different cases: the representation of bone fractures of the lower extremities, by traffic accidents, in a non-invasive manner; the comparison of bone injuries with the presumed injury-inflicting instrument; and in a gunshot case, the identification of the gun by the muzzle imprint, and the reconstruction of the holding position of the gun. The 3D models of the bones are generated from the Computed Tomography (CT) images. The 3D models of the exterior injuries, the injury-inflicting tools and the bone injuries, where a higher resolution is necessary, are created by the optical surface scan. The haptic device is used in combination with the software FreeForm Modelling Plus for touching the surface of the 3D models to feel the minute injuries and the surface of tools, to reposition displaced bone parts and to compare an injury-causing instrument with an injury. The repositioning of 3D models in a reconstruction is easier, faster and more precisely executed by means of using the sense of touch and with the user-friendly movement in the 3D space. For representation purposes, the fracture lines of bones are coloured. This work demonstrates that the haptic device is a suitable and efficient application in forensic science. The haptic device offers a new way in the handling of digital data in the virtual 3D space.