On the prevalence of flow instabilities from high-fidelity computational fluid dynamics of intracranial bifurcation aneurysms.

High-fidelity computational fluid dynamics (HF-CFD) has revealed the potential for high-frequency flow instabilities (aka "turbulent-like" flow) in intracranial aneurysms, consistent with classic in vivo and in vitro reports of bruits and/or wall vibrations. However, HF-CFD has typically been performed on limited numbers of cases, often with unphysiological inflow conditions or focused on sidewall-type aneurysms where flow instabilities may be inherently less prevalent. Here we report HF-CFD of 50 bifurcation aneurysm cases from the open-source Aneurisk model repository. These were meshed using quadratic finite elements having an average effective spatial resolution of 0.065 mm, and solved under physiologically-pulsatile flow conditions using a well-validated, minimally-dissipative solver with 20,000 time-steps per cardiac cycle Flow instability was quantified using the recently introduced spectral power index (SPI), which quantifies, from 0 to 1, the power associated with velocity fluctuations above those of the driving inflow waveform. Of the 50 cases, nearly half showed regions within the sac having SPI up to 0.5, often with non-negligible power into the 100's of Hz, and roughly 1/3 had sac-averaged SPI > 0.1. High SPI did not significantly predict rupture status in this cohort. Proper orthogonal decomposition of cases with highest SPIavg revealed time-varying energetics consistent with transient turbulence. Our reported prevalence of high-frequency flow instabilities in HF-CFD modelling of aneurysms suggests that care must be taken to avoid routinely overlooking them if we are to understand the highly dynamic mechanical forces to which some aneurysm walls may be exposed, and their prevalence in vivo.

When good bacteria behave badly: a case report of Bacillus clausii sepsis in an immunocompetant adult.

Reports of unusual microorganisms causing human infections are on the rise due to transitions in epidemiological trends. Commensal/normal flora which are otherwise termed as 'good bacteria' are now causing infections in different group of patients, mostly immunocompromised individuals. Various host and environmental factors play a pivotal role in microbial transmigration from their normal habitat into the blood and other body sites. We report one such 'good bacterium' associated with sepsis in a patient who was given the same bacterium in the form of probiotics.

Assessment of three-dimensional setup errors in image-guided pelvic radiotherapy for uterine and cervical cancer using kilovoltage cone-beam computed tomography and its effect on planning target volume margins.

PURPOSE: To achieve the best possible therapeutic ratio using high-precision techniques (image-guided radiation therapy/volumetric modulated arc therapy [IGRT/VMAT]) of external beam radiation therapy in cases of carcinoma cervix using kilovoltage cone-beam computed tomography (kV-CBCT). MATERIALS AND METHODS: One hundred and five patients of gynecological malignancies who were treated with IGRT (IGRT/VMAT) were included in the study. CBCT was done once a week for intensity-modulated radiation therapy and daily in IGRT/VMAT. These images were registered with the planning CT scan images and translational errors were applied and recorded. In all, 2078 CBCT images were studied. The margins of planning target volume were calculated from the variations in the setup. RESULTS: The setup variation was 5.8, 10.3, and 5.6 mm in anteroposterior, superoinferior, and mediolateral direction. This allowed adequate dose delivery to the clinical target volume and the sparing of organ at risks. CONCLUSION: Daily kV-CBCT is a satisfactory method of accurate patient positioning in treating gynecological cancers with high-precision techniques. This resulted in avoiding geographic miss.

Durable keratin-based bilayered electrospun mats for wound closure.

A bilayered nanofibrous scaffold with rapid wound healing properties is found to be suitable for tissue regeneration applications. The objective of this study is to reveal the fabrication of a poly(3-hydroxybutyric acid) (P)-gelatin (G) nanofibrous mat through electrospinning, with a horn keratin-chitosan-based biosheet (KC) as a bilayered nanofibrous scaffold. The mupirocin (D)-loaded horn KC biosheet (KCD) acts as the primary layer over which PG nanofibers were electrospun to act as the secondary layer. It is shown that this engineered bilayered nanofibrous scaffold material (KC-PG) should fulfill the functions of the extracellular matrix (ECM) by elucidating its function in vitro and in vivo. The bilayered nanofibrous scaffold was designed to exhibit improved physiochemical, biological and mechanical properties, with better swelling and porosity for enhanced oxygen permeability, and it also exhibits an acceptable antibacterial property to prevent infection at the wound site. The bilayered nanofibrous scaffold assists in better biocompatibility towards fibroblast and keratinocyte cell lines. The morphology of the nanofibrous scaffold aids increased cell adhesion and proliferation with cell material interactions. This was elucidated with the help of in vitro fluorescence staining against both cell lines. The bilayered KCD-PG nanofibrous scaffold material gives accelerated wound healing efficiency during in vivo wound healing. The results showed the regulation of growth factors with enhanced collagen synthesis, thereby helping in faster wound healing.

Electrospun Fibrous Nanocomposite Membrane for UV Shielding Applications.

In this paper, UV shielding properties of the fibrous composite membranes of PVA and ZnO have been studied and analyzed. Two kinds of approches have been adopted to prepare the fibrous membrane and their corresponding effect on shielding properties have also been systematically studied. It has been observed that the pure PVA fibrous membrane with a wavelength longer than 230 nm could not be filtered which predicted that transparency of the pure PVA samples for both UVA and UVB radiations. In the case of DDM derived composite membrane, UV radiations in the range from 200 to 365 nm have been efficiently absorbed by the sample. The ISM-PVA/ZnO exhibit impressive UV shielding nature which effectively filtered the whole range of UV radiation especially for both UV-B (280-315 nm) and UV-A (315-400 nm). The transmittance results indicate a significant improvement of the UV absorbing property of ISM derived ZnO/PVA. Considering the simplicity of the fabrication of the composite materials, this work might become very useful for commercial exploitation.

Engineering of a polymer layered bio-hybrid heart valve scaffold.

Current treatment strategy for end stage valve disease involves either valvular repair or replacement with homograft/mechanical/bioprosthetic valves. In cases of recurrent stenosis/ regurgitation, valve replacement is preferred choice of treatment over valvular repair. Currently available mechanical valves primarily provide durability whereas bioprosthetic valves have superior tissue compatibility but both lack remodelling and regenerative properties making their utility limited in paediatric patients. With advances in tissue engineering, attempts have been made to fabricate valves with regenerative potential using various polymers, decellularized tissues and hybrid scaffolds. To engineer an ideal heart valve, decellularized bovine pericardium extracellular matrix (DBPECM) is an attractive biocompatible scaffold but has weak mechanical properties and rapid degradation. However, DBPECM can be modified with synthetic polymers to enhance its mechanical properties. In this study, we developed a Bio-Hybrid scaffold with non-cross linked DBPECM in its native structure coated with a layer of Polycaprolactone-Chitosan (PCL-CH) nanofibers that displayed superior mechanical properties. Surface and functional studies demonstrated integration of PCL-CH to the DBPECM with enhanced bio and hemocompatibility. This engineered Bio-Hybrid scaffold exhibited most of the physical, biochemical and functional properties of the native valve that makes it an ideal scaffold for fabrication of cardiac valve with regenerative potential.

Preparation and characterization of electrospun curcumin loaded poly(2-hydroxyethyl methacrylate) nanofiber--a biomaterial for multidrug resistant organisms.

Curcumin loaded poly(2-hydroxy ethyl methacrylate) p(HEMA) nanofiber were produced using electrospinning method and characterized. The nanofibrous scaffold supports good cell growth, attachment and retains its original morphology. Sustained and controlled release pattern of curcumin seen to be efficient against infectious disease caused by multidrug resistant organisms. Antibacterial activity of curcumin against Methicillin resistant staphylococcus aureus (MRSA) and extended spectrum ß lactamase (ESBL) proved to be a good alternate herbal compound for antibiotics. Hence the results indicate p(HEMA) nanofiber loaded with curcumin have potential to use as patch in wound healing of infectious disease caused by multidrug resistant organisms and excellent drug delivery vessel.

Optical, bactericidal and water repellent properties of electrospun nano-composite membranes of cellulose acetate and ZnO.

In this report, ZnO nanoparticles embedded cellulose acetate (CA) fibrous membrane with multifunctional properties have been prepared through electrospinning method. The morphology of the electrospun composite membrane was analyzed by scanning electron microscope (SEM). It was found that the polymer concentration in the solution has a significant effect on the morphology of the fibers. The optical property of the sample was tested using photo luminescence (PL) spectra. There is no significant change in the emission features of cellulose acetate with the addition of ZnO. The anti-bacterial property of the sample was studied using disk diffusion method. The wettability of the pure and composite fibrous membrane was also studied by measuring the contact angle of water on the membrane. It was observed that the embedded ZnO in the CA was responsible for the hydrophobic nature of the surface.

Optical and magnetic studies of electrospun Mn-doped SnO2 hollow nanofiber dilute magnetic semiconductor.

The hollow nanofibers of Mn-doped SnO2 were fabricated by electrospinning method. The structural and magnetic properties of the electrospun fibers calcined at 600 degrees C were studied. X-ray diffraction patterns of the nanofibers showed broad diffraction peaks and were indexed to the characteristic diffraction pattern of tetragonal SnO2. The hollow fiber micro-structure of Mn-doped and pure SnO2 were confirmed from the observed HRSEM and TEM analysis. Typical diameter of the hollow nanofibers was found to be around 150 nm. Strong emission peak in the visible region of the PL spectra characteristic of the optical activity of the SnO2 is obtained. Surface composition of the nanofiber and successful incorporation of Mn into SnO2 were confirmed from intense peaks recorded in the XPS spectra. Finally, a reasonable ferromagnetic transition observed at 10 K in the Mn-doped SnO2, substantiates that the presence of undetectable Sn-Mn solid solution or the formation of Mn based oxide secondary phases. It concludes that the induced ferromagnetism is only due to the precipitated impurity phases and does not arise from any intrinsic pure SnO2 or the dopant.

Fabrication of hierarchical ZnO enriched fibrous PVA membrane.

We have demonstrated herein a simple method for the fabrication of hierarchical structure of ZnO enriched fibrous PVA membrane. The observed result has shown the uniform coating of ZnO on the fiber surface. Effective control of the density of coating has been brought about by changing the concentration of ZnO and combined sol-gel coating. Serving as seeds for the growth of nanorods, the ZnO nuclei evolve to form nanorods whose density and length have been controlled by thermal treatment. We believe that the methodology described in this report offers a simple and straightforward route to prepare the hybrid structure and furthermore find an exercise in various optoelectronic fields.

Wettability of Y2O3: A Relative Analysis of Thermally Oxidized, Reactively Sputtered and Template Assisted Nanostructured Coatings.

The wettability of reactively sputtered Y2O3, thermally oxidized Y-Y2O3 and Cd-CdO template assisted Y2O3 coatings has been studied. The wettability of as-deposited Y2O3 coatings was determined by contact angle measurements. The water contact angles for reactively sputtered, thermally oxidized and template assisted Y2O3 nanostructured coatings were 99°, 117° and 155°, respectively. The average surface roughness values of reactively sputtered, thermally oxidized and template assisted Y2O3 coatings were determined by using atomic force microscopy and the corresponding values were 3, 11 and 180 nm, respectively. The low contact angle of the sputter deposited Y2O3 and thermally oxidized Y-Y2O3 coatings is attributed to a densely packed nano-grain like microstructure without any void space, leading to low surface roughness. A water droplet on such surfaces is mostly in contact with a solid surface relative to a void space, leading to a hydrophobic surface (low contact angle). Surface roughness is a crucial factor for the fabrication of a superhydrophobic surface. For Y2O3 coatings, the surface roughness was improved by depositing a thin film of Y2O3 on the Cd-CdO template (average roughness = 178 nm), which resulted in a contact angle greater than 150°. The work of adhesion of water was very high for the reactively sputtered Y2O3 (54 mJ/m²) and thermally oxidized Y-Y2O3 coatings (43 mJ/m²) compared to the Cd-CdO template assisted Y2O3 coating (7 mJ/m²).

Electrospun polymer nanofibrous membrane for filtration.

Modern processing techniques in fiber technology combined with novel polymer materials results in new products. Electrospinning is one of the methods to prepare nanofibers of polymer or polymer composite materials. Membranes made out of these nanofibers can be used in variety of applications like filtration, tissue engineering, drug delivery etc. The membrane properties are governed by their surface properties and pore distribution, as well as their morphology. In this paper we are reporting the preparation and characterization of sulfonated poly(ether ether ketone) nanofibers and membrane made out of these fibers. The surface and cross sectional morphologies are characterized using scanning electron microscopy. Further the membrane is characterized for pore size distribution and pure water permeability. This work can be extended for exploring the use of electrospinning nanofibrous membranes for filter application.

The use of computed radiography for routine linear accelerator and simulator quality control.

Computed radiography (CR) systems were originally developed for the purpose of clinical imaging, and there has been much work published on its effectiveness as a film replacement for this end. However, there has been little published on its use for routine linear accelerator and simulator quality control, and therefore we have evaluated the use of the Kodak 2000RT system with large Agfa CR plates as a replacement for film for this function. A prerequisite for any such use is a detailed understanding of the system behaviour, hence characteristics such as spatial uniformity of response, reproducibility of spatial accuracy, plate signal decay with time and the dose-response of plates were investigated. Finally, a comparison of results obtained using CR for the measurement of radiation field dimensions was made against those from radiographic film, and found to be in agreement within 0.1 mm (mean difference for high-resolution images, 0.3 mm root mean square difference) for megavoltage images and 0.3 mm (maximum difference) for simulator images. In conclusion, the CR system has been shown to be a good alternative to radiographic film for routine quality control of linear accelerators and simulators.

Preparation and characterization of polystyrene-multiwalled carbon nanotube composite fibers by electrospinning.

Electrospinning is a simple technique to prepare polymer fibers in nanometer diameters using very high electrostatic fields. These nanofibers are useful in many applications since the surface area to volume ratio in these fibers is very high. Here we have prepared nanofibers of composites of Polystyrene (PS) with different concentrations (0.05% to 2% w/w) of multi-walled carbon nanotubes (MWCNT) by electrospinning. The fibers are characterized by SEM, TEM, Raman spectra, and TGA. The room temperature electrical conductivity of single fibers of these composites are measured and found to show dramatic improvement in the conductivity due to the addition of MWCNT to the polymer matrix compared to the pure PS.

Autoradiographic and SPECT imaging of cerebral opioid receptors with an iodine-123 labeled analogue of diprenorphine.

The feasibility of imaging cerebral opioid receptors by single photon emission computed tomography (SPECT) has been established in baboon using a novel analog of diprenorphine (DPN) radiolabeled with iodine-123. The radioligand, [123I]-O-IA-DPN (C6-O-[123I]iodoallyl-DPN), was prepared in good yield (80%) with high radiochemical purity (>97%) and high specific radioactivity (>2,400 mCi/micromol). In ex vivo autoradiographic studies, with and without naltrexone blockade, [123I]-O-IA-DPN specifically labeled opioid receptors throughout the mouse brain. Nonmetabolized radioligand accounted for >90% of the signal observed in extracts of whole mouse brain. SPECT imaging trials showed that [123I]-O-IA-DPN selectively localized in regions of baboon brain known to have high densities of opioid receptors, such as striatum, thalamus, and temporal cortex. A much lower level of radioligand uptake and retention was noted for cerebellum, a region with few opioid binding sites. Pretreatment with naltrexone (6.5 pmol/kg) blocked [123I]-O-IA-DPN binding in all brain regions. Using naltrexone blockade to define the nonspecific component for a given region of interest, total to nonspecific binding ratios increased linearly (r > or = 0.98) over the SPECT study with maximal values for striatum (9.8), thalamus (7.1), and temporal cortex (6.9) reached at the last time point investigated (3.5 h). Specific binding for these regions, assessed as the difference between regional SPECT activity for the control and blocked states, proved irreversible over the observation period. By the end of the time course, specific [123I]-O-IA-DPN binding was >85% of total radioactivity in regions rich in opioid receptors and 62% of total radioactivity in cerebellum. The aggregate data are consistent with visualization of multiple opioid receptor types. Thus, [123I]-O-IA-DPN should prove useful for SPECT studies within the constraints imposed by a lack of innate selectivity for a single type of brain opioid receptor.

Clinicopathological correlation of technetium bone scan in vascularization of hydroxyapatite implants. A primate model.

OBJECTIVES: To report the histopathological and bone scan characteristics of the stages of hydroxyapatite fibrovascular integration and to consider the implications for the timing of peg drilling in a primate model. DESIGN: Three monkeys received hydroxyapatite implants covered only anteriorly with a fascia lata button to which the rectus muscles were sutured. Weekly bone scans were evaluated quantitatively and qualitatively. The orbits were harvested at 2, 4, and 8 weeks and examined histopathologically. RESULTS: Quantitatively, the implant's technetium uptake increased, then reached a plateau by 4 weeks. Peripheral uptake was present on the images and histologically at 2 weeks. When bone scan images suggested complete vascularization by the fourth week, the implant was 99% vascularized histologically. Completion of vascularization was ascertained at 8 weeks, without further discernible changes in the bone scans. CONCLUSIONS: The technetium bone scan is sensitive to the vascularization of the hydroxyapatite implant and discerns when complete vascularization is approached. This primate study models closely the clinical findings we have recently reported. We advocate at least a 4-week interval between the time the bone scan suggests full vascularization and peg drilling.

Quantitative measurement of vascularization and vascular ingrowth rate of coralline hydroxyapatite ocular implant by Tc-99m MDP bone imaging.

Complete fibrovascular ingrowth of the hydroxyapatite ocular implant is necessary for peg drilling, the secondary procedure that couples the mobile sphere to the ocular prosthesis providing it with motility. This study was conducted to determine the usefulness of the bone scan for the evaluation and relative quantification of the vascularization of coralline hydroxyapatite ocular implants. In 23 patients (32 scans), vascularization of the ocular implant was measured by three-phase bone scintigraphy. There were 16 patients with left, and 7 with right orbital implants. At followup 0.5 to 8 months after successful hydroxyapatite implantation, the mean implant to normal intraorbital activity ratio on delayed bone scans in anterior view was 2.73 +/- 0.73 (mean +/- SD) with a range of 1.42-4.2. The normal right to left and left to right intraorbital bone activity ratios determined in anterior view from 10 normal delayed bone scans were 0.98 +/- 0.05 (mean +/- SD) and 1.02 +/- 0.05 (mean +/- SD) respectively, with a range of 0.93-1.07. The difference of the activity (count) ratios among the successfully implanted group and normals was statistically significant (P < 0.0001). A hydroxyapatite ocular implant to contralateral intraorbital bone activity ratio of greater than 1.12 with a homogeneous tracer distribution throughout the implant suggests adequate and diffuse vascularization is present. The progressive increase in activity ratio of the orbital implants seen in the early postimplantation period, which is indicative of the progression of vascularization, reaches a plateau after 1 month and remains relatively stable thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

Multimodality correlative study of canine brain tumors. Proton magnetic resonance spectroscopy, positron emission tomography, and histology.

RATIONALE AND OBJECTIVES: Structural/functional relationships in an induced canine brain tumor were studied using proton-magnetic resonance spectroscopy (1H-MRS), positron emission tomography (PET), and histology. METHODS: Proton-MRS and PET data of implanted canine brain tumors were correlated with quantitative analysis of the tissue composition within the MRS and PET regions of interest (ROIs). Linear regression analysis was employed to correlate the 1H-MRS and PET data with the percent tumor and the percent total lesion (comprising tumor plus associated pathology ie, edema, cysts, hemorrhage, inflammation) within the ROI. RESULTS: Using 1H-MRS, N-acetyl aspartate concentrations were indirectly correlated with the amount of tumor (P = .058), as well as the amount of tumor plus associated pathology (P = .032) within the ROI. Total creatine concentrations were indirectly correlated with the amount of tumor and the amount of tumor plus associated pathology within the ROI (P < .05). Lactate concentrations were directly correlated with the amount of tumor (P = .053) and the amount of tumor plus associated pathology (P = .058) within the ROI. Using PET, Oxygen metabolic rates were indirectly correlated with the amount of tumor and with the amount of tumor plus associated pathology within the ROI (P < .05). Glucose metabolic rates were directly correlated with both the amount of tumor and with the amount of tumor plus associated pathology at P < .05. Proton-MRS measured concentrations of choline and PET measured values for blood flow, and oxygen extraction showed correlations with the amount of tumor and with the amount of tumor plus associated pathology at P > or = .08. CONCLUSIONS: The PET and MRS data were complementary with respect to suggesting anaerobic glucose metabolism for the tumor. Unlike other tumors, no increase in choline was noted in the canine tumor.

Comparison of [11C]diprenorphine and [11C]carfentanil in vivo binding to opiate receptors in man using a dual detector system.

A simple dual detector coincidence system was used to measure the binding of [11C]carfentanil and [11C]diprenorphine to opiate receptors in normal volunteers before and after the administration of naloxone. Total radioactivity without naloxone and the ratio of total/non-specific radioactivity was 2 times greater for [11C]diprenorphine than [11C]carfentanil. The dose of naloxone required to maximally block specific [11C]diprenorphine binding was 10 times that for [11C]carfentanil, indicating that [11C]diprenorphine labels opiate receptor subtypes in addition to mu opiate receptors.

Noncompartmental and compartmental modeling of the kinetics of carbon-11 labeled pyrilamine in the human brain.

The kinetic pattern of a 11C-labeled histamine H1 receptor antagonist, [11C]pyrilamine, was investigated in the human brain by factor analysis of dynamic PET studies. Tissue time activity curves were also processed by compartment model curve fitting preceded by deconvolution analysis. Factor analysis revealed two statistically significant and physiologically meaningful kinetic patterns: one for specific and another for nonspecific binding of the radioligand. From these two factors a compartment model containing two tissue compartments (one for specific binding and another for nonspecific binding and free ligand) was constructed. The two-compartment model was also supported by the impulse response function, which was obtained by deconvolution and showed two components. The factor image constructed from factor two demonstrated a distribution pattern characteristic for brain regions rich (frontal, parietal, and temporal lobes) or poor (occipital lobe and cerebellum) in H1 receptors. Blockade of H1 receptors with unlabeled pyrilamine, diphenhydramine, or hydroxyzine caused a significant reduction of this factor. Blockade produced no significant changes in factor one representing nonspecific binding. We conclude that the kinetics of [11C]pyrilamine in the brain can be described by two tissue compartments, one related to the distribution of the H1 receptors. Factor analysis of dynamic studies can be used to locally separate these two compartments, for identification of regions rich and poor in H1 receptors and for noninvasive quantitative investigation of the effects of H1 receptor blockers such as pyrilamine, diphenhydramine, or hydroxyzine.