368 research outputs found

    In vivo effect of FK506 on human pancreatic islets

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    The purpose of this study was to evaluate the in vivo effect of FK506 on human pancreatic islets. Twenty-five nude mice were made diabetic by one intravenous injection of streptozotocin. Approximately 600 islets were administered in the renal subcapsular space 3-5 days following streptozotocin administration. One week after transplantation, the mice were divided in four groups. In group 1, the animals received 1 injection of 0.5 ml of diluent i.p. daily for one week. In groups 2, 3, and 4 the treatments were daily i.p. injection of 0.3, 1, and 3 mg/kg FK506, respectively. After treatment, the functional integrity of the transplanted human islets was tested by measuring the plasma glucose and human C-peptide response to intraperitoneal glucose injection in groups 1 and 4. IPGTT alone was assessed in groups 2 and 3. The results indicate that i.p. administration of FK506 for one week at a dose 0.3 mg/kg/day did not result in any significant alteration of glucose disappearance and C-peptide response to IPGTT. Higher doses of FK506 produced a significant delay in glucose disappearance in groups 3 and 4, and a significant inhibition of glucose-mediated C-peptide response in group 4. © 1991 by Williams and Wilkins

    Building capacity for water, sanitation, and hygiene programming: Training evaluation theory applied to CLTS management training in Kenya

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    Training and capacity building are long established critical components of global water, sanitation, and hygiene (WaSH) policies, strategies, and programs. Expanding capacity building support for WaSH in developing countries is one of the targets of the Sustainable Development Goals. There are many training evaluation methods and tools available. However, training evaluations in WaSH have been infrequent, have often not utilized these methods and tools, and have lacked rigor. We developed a conceptual framework for evaluating training in WaSH by reviewing and adapting concepts from literature. Our framework includes three target outcomes: learning, individual performance, and improved programming; and two sets of influences: trainee and context factors. We applied the framework to evaluate a seven-month community-led total sanitation (CLTS) management training program delivered to 42 government officials in Kenya from September 2013 to May 2014. Trainees were given a pre-training questionnaire and were interviewed at two weeks and seven months after initial training. We qualitatively analyzed the data using our conceptual framework. The training program resulted in trainees learning the CLTS process and new skills, and improving their individual performance through application of advocacy, partnership, and supervision soft skills. The link from trainees' performance to improved programming was constrained by resource limitations and pre-existing rigidity of trainees’ organizations. Training-over-time enhanced outcomes and enabled trainees to overcome constraints in their work. Training in soft skills is relevant to managing public health programs beyond WaSH. We make recommendations on how training programs can be targeted and adapted to improve outcomes. Our conceptual framework can be used as a tool both for planning and evaluating training programs in WaSH

    Scanning in Situ Spectroscopy Pplatform for Imaging Surgical Breast Tissue Specimens

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    A non-contact localized spectroscopic imaging platform has been developed and optimized to scan 1 x 1 cm² square regions of surgically resected breast tissue specimens with ~150-micron resolution. A color corrected, image-space telecentric scanning design maintained a consistent sampling geometry and uniform spot size across the entire imaging field. Theoretical modeling in ZEMAX allowed estimation of the spot size, which is equal at both the center and extreme positions of the field with ~5% variation across the designed waveband, indicating excellent color correction. The spot sizes at the center and an extreme field position were also measured experimentally using the standard knife-edge technique and were found to be within ~8% of the theoretical predictions. Highly localized sampling offered inherent insensitivity to variations in background absorption allowing direct imaging of local scattering parameters, which was validated using a matrix of varying concentrations of Intralipid and blood in phantoms. Four representative, pathologically distinct lumpectomy tissue specimens were imaged, capturing natural variations in tissue scattering response within a given pathology. Variations as high as 60% were observed in the average reflectance and relative scattering power images, which must be taken into account for robust classification performance. Despite this variation, the preliminary data indicates discernible scatter power contrast between the benign vs malignant groups, but reliable discrimination of pathologies within these groups would require investigation into additional contrast mechanisms

    Nonlinear Control for Reconfiguration of Unmanned-Aerial-Vehicle Formation

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76757/1/AIAA-8760-121.pd

    Video-Rate Near Infrared Tomography to Image Pulsatile Absorption Properties in Thick Tissue

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    A high frame-rate near-infrared (NIR) tomography system was created to allow transmission imaging of thick tissues with spectral encoding for parallel source implementation. The design was created to maximize tissue penetration through up to 10 cm of tissue, allowing eventual use in human imaging. Eight temperature-controlled laser diodes (LD) are used in parallel with 1.5 nm shifts in their lasing wavelengths. Simultaneous detection is achieved with eight high-resolution, CCD-based spectrometers that were synchronized to detect the intensities and decode their source locations from the spectrum. Static and dynamic imaging is demonstrated through a 64 mm tissue-equivalent phantom, with acquisition rates up to 20 frames per second. Imaging of pulsatile absorption changes through a 72 mm phantom was demonstrated with a 0.5 Hz varying object having only 1% effect upon the transmitted signal. This subtle signal change was used to show that while reconstructing the signal changes in a tissue may not be possible, image-guided recovery of the pulsatile change in broad regions of tissue was possible. The ability to image thick tissue and the capacity to image periodic changes in absorption makes this design well suited for tracking thick tissue hemodynamics in vivo during MR or CT imaging

    Anthropomorphic Breast Phantoms with Physiological Water, Lipid, and Hemoglobin Content for Near-Infrared Spectral Tomography

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    Breast mimicking tissue optical phantoms with sufficient structural integrity to be deployed as stand-alone imaging targets are developed and successfully constructed with biologically relevant concentrations of water, lipid, and blood. The results show excellent material homogeneity and reproducibility with inter- and intraphantom variability of 3.5 and 3.8%, respectively, for water and lipid concentrations ranging from 15 to 85%. The phantoms were long-lasting and exhibited water and lipid fractions that were consistent to within 5% of their original content when measured 2 weeks after creation. A breast-shaped three-compartment model of adipose, fibroglandular, and malignant tissues was created with water content ranging from 30% for the adipose simulant to 80% for the tumor. Mean measured water content ranged from 30% in simulated adipose to 73% in simulated tumor with the higher water localized to the tumor-like material. This novel heterogeneous phantom design is composed of physiologically relevant concentrations of the major optical absorbers in the breast in the near-infrared wavelengths that should significantly improve imaging system characterization and optimization because the materials have stand-alone structural integrity and can be readily molded into the sizes and shapes of tissues commensurate with clinical breast imaging
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