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Motion of patients undergoing cardiac SPECT perfusion imaging causes artifacts in the acquired images which may lead to difficulty in interpretation. Our work investigates a technique of obtaining patient motion estimates from retro-reflective markers on stretchy bands wrapped around the chest and abdomen of patients being imaged clinically. Motion signals obtained from the markers consist of at least two components, body motion (BM) and periodic motion (PM) due to respiration. We present a method for separating these components from the motion-tracking data of each marker, and then report a method for combining the BM estimated from chest markers to estimate the 6-degree-of-freedom (6-DOF) rigid-body motion (RBM) of the heart. Motion studies of volunteers and patients are used to evaluate the methods. Illustrative examples of the motion of the heart due to patient body movement and respiration (upward creep) are presented and compared to estimates of the motion of the heart obtained directly from SPECT data. Our motion-tracking method is seen to give reasonable agreement with the motion-estimates from the SPECT data while being considerably less noisy. Index Terms--Motion estimation, signal processing, single photon emission computed tomography.

A simple method of preparing amorphous nickel ferrite nanoparticles of about 5 nm diameter is described. These particles were characterized by dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The nanoparticles were evaluated for their use as a magnetic material for immobilized metal affinity chromatography (IMAC). The ferrite nanoparticles bound to bovine serum albumin (BSA) and the binding fitted Langmuir isotherm model. A high capacity of 916 mg BSA/g dried nanoparticle was observed. Six proteins (Soybean trypsin inhibitor (STI), lactate dehydrogenase (LDH), papain, catalase, β-galactosidase and casein) were used and all were found to bind at >90% level (except papain which showed 84% binding). All the proteins except LDH and β-galactosidase could be eluted with 1 M imidazole and with % activity recovery of >80%. Papain could be purified from its dried crude latex by 5-fold and purified papain showed a single band on SDS-PAGE. These nanoparticles constitute a high capacity and are magnetic material useful for IMAC and do not require any pre-functionalization. [ABSTRACT FROM AUTHOR]

T cells play an important role in controlling viral replication during HIV infection. An effective vaccine should, therefore, lead to the induction of a strong and early viral-specific CD8+ T cell response. While polyfunctional T cell responses are thought to be important contributors to the antiviral response, there is evidence to show that polyfunctional HIV- specific CD8+ T cells are just a small fraction of the total HIV-specific CD8+ T cells and may be absent in many individuals who control HIV replication, suggesting that other HIV-1 specific CD8+ effector T cell subsets may be key players in HIV control. Stem cell-like memory T cells (TSCM) are a subset of T cells with a long half-life and self-renewal capacity. They serve as key reservoirs for HIV and contribute a significant barrier to HIV eradication. The present study evaluated vaccine-induced antiviral responses and TSCM cells in volunteers vaccinated with a subtype C prophylactic HIV-1 vaccine candidate administered in a prime-boost regimen. We found that ADVAX DNA prime followed by MVA boost induced significantly more peripheral CD8+ TSCM cells and higher levels of CD8+ T cell-mediated inhibition of replication of different HIV-1 clades as compared to MVA alone and placebo. These findings are novel and provide encouraging evidence to demonstrate the induction of TSCM and cytotoxic immune responses by a subtype C HIV-1 prophylactic vaccine administered using a prime-boost strategy. [ABSTRACT FROM AUTHOR]

Effective vaccine design relies on accurate knowledge of protection against a pathogen, so as to be able to induce relevant and effective protective responses against it. An ideal Human Immunodeficiency virus (HIV) vaccine should induce humoral as well as cellular immune responses to prevent initial infection of host cells or limit early events of viral dissemination. A Phase I HIV-1 prophylactic vaccine trial sponsored by the International AIDS Vaccine Initiative (IAVI) was conducted in India in 2009.The trial tested a HIV-1 subtype C vaccine in a prime-boost regimen, comprising of a DNA prime (ADVAX) and Modified Vaccine Ankara (MVA) (TBC-M4) boost. The trial reported that the vaccine regimen was safe, well tolerated, and resulted in enhancement of HIV-specific immune responses. However, preliminary immunological studies were limited to vaccine-induced IFN-γ responses against the Env and Gag peptides. The present study is a retrospective study to characterize in detail the nature of the vaccine-induced cell mediated immune responses among volunteers, using Peripheral Blood Mononuclear Cells (PBMC) that were archived during the trial. ELISpot was used to measure IFN-γ responses and polyfunctional T cells were analyzed by intracellular multicolor flow cytometry. It was observed that DNA priming and MVA boosting induced Env and Gag specific bi-functional and multi-functional CD4+ and CD8+ T cells expressing IFN-γ, TNF-α and IL-2. The heterologous prime-boost regimen appeared to be slightly superior to the homologous prime-boost regimen in inducing favorable cell mediated immune responses. These results suggest that an in-depth analysis of vaccine-induced cellular immune response can aid in the identification of correlates of an effective immunogenic response, and inform future design of HIV vaccines. [ABSTRACT FROM AUTHOR]

Purpose: Single‐photon emission computed tomography (SPECT) is a noninvasive imaging modality, used in myocardial perfusion imaging. The challenges facing the majority of clinical SPECT systems are low sensitivity, poor resolution, and the relatively high radiation dose to the patient. New generation systems (GE Discovery, DSPECT) dedicated to cardiac imaging improve sensitivity by a factor of 5–8. This improvement can be used to decrease acquisition time and/or dose. However, in the case of ultra‐low dose (~3 mCi) injections, acquisition times are still significantly long, taking 10–12 min. The purpose of this work is to investigate a new gamma camera design with 21 hemi‐ellipsoid detectors each with a pinhole collimator for cardiac SPECT for further improvement in sensitivity and resolution and reduced patient exposures and imaging times. Methods: To evaluate the resolution of our hemi‐ellipsoid system, GATE Monte‐Carlo simulations were performed on point‐sources, rod‐sources, and NCAT phantoms. For average full‐width‐half‐maximum (FWHM) equivalence with base flat‐detector, the pinhole‐diameter for the curved hemi‐ellipsoid detector was found to be 8.68 mm, an operating pinhole‐diameter nominally expected to be ~3 times more sensitive than state‐of‐the‐art systems. Rod‐sources equally spaced within the region of interest were acquired with a 21‐detector system and reconstructed with our multi‐pinhole (MPH) iterative OSEM algorithm with collimator resolution recovery. The results were compared with the results of a state‐of‐the‐art system (GE Discovery) available in the literature. The system was also evaluated using the mathematical anthropomorphic NCAT (NURBS‐based Cardiac Torso; Segars et al. IEEE Trans Nucl Sci. 1999;46:503–506) phantom with a full (clinical)‐dose acquisition (25 mCi) for 2 min and an ultra‐low dose acquisition of 3 mCi for 5.44 min. The estimated left ventricle (LV) counts were compared with the available literature on a state‐of‐the‐art system (DSPECT). FWHM of the LV wall on MPH‐OSEM‐reconstructed images with collimator resolution recovery was estimated. Results: On acquired rod‐sources, the average resolution (FWHM) after reconstruction with resolution recovery in the entire region of interest (ROI) for cardiac imaging was on the average 4.44 mm (±2.84), compared to 6.9 mm (±1 mm) reported for GE Discovery (Kennedy et al., J Nucl Cardiol. 2014:21:443–452). For NCAT studies, improved sensitivity allowed a full‐dose (25 mCi) 2‐min acquisition (Ell8.68mmFD) which yielded 3.79 M LV counts. This is ~3.35 times higher compared to 1.13 M LV counts acquired in 2 min for clinical full dose for state‐of‐the‐art DSPECT. The increased sensitivity also allowed an ultra‐low dose acquisition protocol (Ell8.68 mmULD), 3 mCi (eight times less injected dose) in 5.44 min. This ultra‐low dose protocol yielded ~1.23 M LV counts which was comparable to the full‐dose 2‐min acquisition for DSPECT. The estimated NCAT average FWHM at the LV wall after 12 iterations of the OSEM reconstruction was 4.95 and 5.66 mm around the mid‐short‐axis slices for Ell8.68mmFD and Ell8.68mmULD, respectively. Conclusion: Our Monte‐Carlo simulation studies and reconstruction suggest using (inverted wineglass sized) hemi‐ellipsoid detectors with pinhole collimators can increase the sensitivity ~3.35 times over the new generation of dedicated cardiac SPECT systems, while also improving the reconstructed resolution for rod‐sources with an average of 4.44 mm in region of interest. The extra sensitivity may be used for ultra‐low dose imaging (3 mCi) at ~5.44 min for comparable clinical counts as state‐of‐the‐art systems. [ABSTRACT FROM AUTHOR]