Robust semi-automatic segmentation of pulmonary subsolid nodules in chest computed tomography scans.

The malignancy of lung nodules is most often detected by analyzing changes of the nodule diameter in follow-up scans. A recent study showed that comparing the volume or the mass of a nodule over time is much more significant than comparing the diameter. Since the survival rate is higher when the disease is still in an early stage it is important to detect the growth rate as soon as possible. However manual segmentation of a volume is time-consuming. Whereas there are several well evaluated methods for the segmentation of solid nodules, less work is done on subsolid nodules which actually show a higher malignancy rate than solid nodules. In this work we present a fast, semi-automatic method for segmentation of subsolid nodules. As minimal user interaction the method expects a user-drawn stroke on the largest diameter of the nodule. First, a threshold-based region growing is performed based on intensity analysis of the nodule region and surrounding parenchyma. In the next step the chest wall is removed by a combination of a connected component analyses and convex hull calculation. Finally, attached vessels are detached by morphological operations. The method was evaluated on all nodules of the publicly available LIDC/IDRI database that were manually segmented and rated as non-solid or part-solid by four radiologists (Dataset 1) and three radiologists (Dataset 2). For these 59 nodules the Jaccard index for the agreement of the proposed method with the manual reference segmentations was 0.52/0.50 (Dataset 1/Dataset 2) compared to an inter-observer agreement of the manual segmentations of 0.54/0.58 (Dataset 1/Dataset 2). Furthermore, the inter-observer agreement using the proposed method (i.e. different input strokes) was analyzed and gave a Jaccard index of 0.74/0.74 (Dataset 1/Dataset 2). The presented method provides satisfactory segmentation results with minimal observer effort in minimal time and can reduce the inter-observer variability for segmentation of subsolid nodules in clinical routine.

Anthelmintic resistance of intestinal nematodes to ivermectin and pyrantel in Estonian horses.

There is evidence of resistance in horses to anthelmintic treatment using ivermectin and pyrantel. However, little information is available about the parasites, treatment practices or anthelmintic resistance in the horse population in Estonia. In the present study, we examined 41 trotting and riding horses aged < 3 years from four stables in Estonia. Faecal samples were collected, and horses were selected for treatment if the nematode egg count per gram faeces exceeded 200. Horses (n= 32) that shed strongyle-type eggs were treated with pyrantel, whereas Parascaris equorum-positive animals received ivermectin. Up to 78% of horses required anthelmintic treatment and the efficiency of the anthelmintics was evaluated using a faecal egg count reduction test. Resistance of P. equorum was observed in 50% of horses treated with ivermectin and of strongyles in 27% of horses treated with pyrantel. Ivermectin treatment resulted in a mean reduction of 100% for strongyle eggs and an 89% reduction in P. equorum, and pyrantel-treated horses exhibited an 88% reduction in strongyle eggs. These results are considered to be the first indication of resistance to pyrantel, but further studies of ivermectin resistance are required. According to questionnaires completed by the owners of horses, resistance might be explained by a lack of evidence-based strategies, a strong preference for using ivermectin and possibly a subjective evaluation of the body weight of horses.

Curved nanowire structures and exciton binding energies.

Growth of quantum-confined semiconductor structures is a complicated process that may lead to imperfect and complex shapes as well as geometrical nonuniformities when comparing a large number of intended identical structures. On the other hand, the possibility of tuning the shape and size of nanostructures allows for extra optimization degrees when considering electronic and optical properties in various applications. This calls for a better understanding of size and shape effects. In the present work, we express the one-band Schrödinger equation in curved coordinates convenient for determining eigenstates of curved quantum-wire and quantum-dash structures with large aspect ratios. Firstly, we use this formulation to solve the problem of single-electron and single-hole states in curved nanowires. Secondly, exciton states for the curved quantum-wire Hamiltonian problem are found by expanding exciton eigenstates on a product of single-particle eigenstates. A simple result is found for the Coulomb matrix elements of an arbitrarily curved structure as long as the radius-of-curvature is much larger than the cross-sectional dimensions. We use this general result to compute the groundstate exciton binding energy of a bent nanowire as a function of the bending radius-of-curvature. It is demonstrated that the groundstate exciton binding energy increases by 40 meV as the radius-of-curvature changes from 20 to 2 nm while keeping the total length (and volume) of the nanowire constant.

Electronic properties of semiconductor nanowires.

This paper provides a review of the state-of-the-art electronic-structure calculations of semiconductor nanowires. Results obtained using empirical k.p, empirical tight-binding, semi-empirical pseudopotential, and with ab initio methods are compared. For conciseness, we will restrict our detailed discussions to free-standing plain and modulated nanowires. Connections to relevant experimental data, particularly band gaps and polarization anisotropy, will be made since these results depend crucially on the electronic properties. For completeness, a brief review on the synthesis of nanowires is included.

[Bacteremia in children with acute lymphoblastic leukemia]. / Bakteriaemi hos børn med akut lymfoblastaer leukaemi.

The purpose of this study was to describe the pattern of bacterial infections in children with acute lymphoblastic leukemia. Forty-six children with ALL were treated for 119 febrile episodes. Antibiotic therapy was initiated with ampicillin and gentamicin, +/- dicloxacillin and lasted for 5-8 days. Bacterial cultures were positive in 36 of 119 febrile events. At the beginning of the febrile disease there was no difference in CRP and neutrophil count between children with positive and negative blood cultures. The maximum CRP was, however, significantly higher in children with positive blood cultures. In 75% there was no need to change the initial antibiotic treatment with ampicillin and gentamicin +/- dicloxacillin. If the temperature has been normal for 2-3 days and the neutrophil count is increasing it appears safe to discontinue the antibiotic therapy after five days when blood cultures are negative and after 7-8 days when cultures are positive.

Sequential Adsorption of Human Serum Albumin (HSA), Immunoglobulin G (IgG), and Fibrinogen (Fgn) at HMDSO Plasma Polymer Surfaces

The sequential adsorption of human serum albumin (HSA), immunoglobulin G (IgG), and fibrinogen (Fgn) at hexamethyldisiloxane (HMDSO) plasma polymer surfaces was investigated with ellipsometry and total internal reflection fluorescence spectroscopy (TIRF) as a function of adsorption time, pH, and excess electrolyte concentration. HSA was found to self-exchange very slowly ( approximately hours) at pH 7.2, irrespective of adsorption time in the range 90 s to 90 min. Preadsorbed HSA was exchanged by Fgn and IgG only to a limited extent irrespectively of pH (5

Competitive Protein Adsorption at Plasma Polymer Surfaces

Competitive adsorption from a ternary mixture of human serum albumin (HSA), human IgG, and human fibrinogen (Fgn) at concentrations corresponding to blood plasma diluted 1/100 was investigated with the combination of Total Internal Reflection Fluorescence spectroscopy (TIRF) and ellipsometry. As substrates, three different plasma polymer surfaces, representing different surface charge and surface energy, were prepared from hexamethyldisiloxane (PP-HMDSO), acrylic acid (PP-AA), and 1,2-diaminocyclohexane (PP-DACH). In addition, adsorption from single and binary protein systems was investigated with ellipsometry. At the hydrophobic PP-HMDSO little or no displacement of any of the proteins was observed. The adsorbed layer was dominated by HSA and IgG, although Fgn was also present to a smaller extent. On PP-DACH and PP-AA, representing positively and negatively charged hydrophilic surfaces, respectively, Fgn completely dominated the adsorbed layer while HSA was almost absent and IgG was present only at a very low level.

Effects of Hydrophilization and Immobilization on the Interfacial Behavior of Immunoglobulins.

The adsorption and immobilization of rabbit anti-human immunoglobulin (rabbit IgG), as well as the effects of rinsing with buffer and addition of bovine serum albumin (BSA) or human IgG on the amount and reactivity of bound rabbit IgG, were investigated with ellipsometry, total internal reflection fluorescence spectroscopy (TIRF), and enzyme immuno assay (EIA). It was found that although rabbit IgG readily adsorbs at hydrophobic hexamethyldisiloxane (HMDSO) plasma polymer surfaces, a substantial fraction of the adsorbed protein molecules is desorbed upon rinsing with buffer. BSA was found to adsorb readily at the surfaces obtained after rinsing, although also this protein desorbed to a large extent (about 60%) upon further rinsing with buffer. The adsorption of BSA causes a further reduction in the amount of rabbit IgG adsorbed. Immobilization of rabbit IgG to acrylic acid (AA) plasma polymer surfaces, achieved by covalent coupling via a strongly adsorbed PEG-PEI copolymer, was found to overcome the problem of the desorption of rabbit IgG upon rinsing with buffer or addition of BSA. Furthermore, nonspecific adsorption was virtually absent after immobilization. However, covalently bound rabbit IgG reacted strongly with human IgG, as observed by ellipsometry, TIRF, and EIA. The immobilization of rabbit IgG to hydrophilized surfaces was found to facilitate the interpretation of EIA results.

The chemiluminescence response of neutrophils on polymer surfaces made by glow discharge plasma polymerization.

Polypropylene tubes were coated with different polymers made by glow discharge plasma polymerization. Isolated human blood neutrophils were allowed to interact with the polymer surface and the chemiluminescence response of the cells was recorded as a measure of oxidative activation. The polymers represented surfaces that differed markedly with respect to charge, hardness, and wettability. We found that all polymers stimulated the chemiluminescence response in neutrophils differently; when preincubation with human serum albumin (HSA) there was a general reduction of the chemiluminescence response particularly on one of the positively charged surface 1,2-diamino-cyclohexane (DACH). Addition of a soluble stimulus, the chemoattractant formylmethionyl-leucylphenylalanine (FMLP), to the cells caused a dramatic increase in the response on one of the hydrophobic surface hexamethylene-disiloxane (HMDSO). However, there was also a pronounced reduction in the response on polymers with acrylic acid (AA). The response was normalized after addition of HSA. Taken together, the chemiluminescence response of the neutrophils interacting with the polymer surfaces differed with regard to the type of surfaces. When HSA and FMLP were added a larger difference in the response was found. Our results showed that the activation of human neutrophil granulocytes influenced by different polymer surfaces, followed unspecific different patterns which were someway related to the specific characteristics of the polymer and from this point we came to similar conclusions made by Kaplan et al. (J. Biomater. Res. 28, 377 (1994)), that it is difficult to extrapolate any activation mechanisms from one material to another.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption of fibrinogen and some other proteins from blood plasma at a variety of solid surfaces.

Enzyme linked immunosorbent assay (ELISA) was used for the estimation of protein adsorption from blood plasma at some model solid surfaces. The majority of those surfaces were made in the wells of microtiterplates of polystyrene commonly used for ELISA purposes. Three of the model surfaces were made by radio frequency plasma discharge polymerization (RFPD) of the microtiterplates of polystyrene. The monomers we used were diaminocyclohexane, hexamethylenedisiloxane, and acrylic acid. Other surfaces investigated were: unmodified polystyrene, oxidized polystyrene, hydrophilic silicon oxide, and methylized silicon oxide. Two substances, Tween and bovine serum albumin (BSA), for the prevention of unintended adsorption of ELISA conjugate were also tested and the BSA method was found to be superior for this kind of investigation. Human blood plasma at different dilutions was incubated in the surface-modified microtiterplates followed by incubation of rabbit antibodies against fibrinogen (FG), fibronectin (FN), human serum albumin (HSA), complement factor 3 (C3), and immunoglobulin G (IgG). Visualization of bound antibodies was then made by standard ELISA procedure. At low blood plasma concentrations (plasma dil 1/1000), anti-IgG and anti-HSA were detected at high levels at the majority of surfaces. At high blood plasma concentration (plasma dil 1/10), anti-FG dominated at most surfaces. ELISA activity of FN and C3 were low at most of the surfaces at both plasma concentrations. An 'optimum' plasma dilution for the detection of surface bound FG (the Vroman effect) was not found with the use of the ELISA on any of the surfaces except for the silicon oxide surface. This is in contrast to findings by others who had used isotope-labelled fibrinogen diluted in plasma. However, 'false' Vroman effects occurred if nonionic surfactant was used for the prevention of unspecific binding in the ELISA.

RF-plasma-modified polystyrene surfaces for studying complement activation.

Five different plasma modified surfaces were made for studying different aspects of biocompatibility. These surfaces were: 1,2-diaminocyclohexane (DACH), acrylic acid (AA), Hydroxyethylmethacrylate (HEMA), methane and hexamethylene-disiloxane (HMDSO). In addition a polyethylene-glycol (PEG) was made by grafting aldehyde functional PEG to the DACH surface. PEG and HMDSO which are the most hydrophilic and the most hydrophobic surface shows the lowest amount of adsorbed protein of the three proteins studied here (albumin, IgG and C3). Methane, HMDSO and HEMA was found to activate via the classical (complement activation) pathway while the others activated via the alternative pathway.