18F-4V for PET–CT Imaging of VCAM-1 Expression in Atherosclerosis

ObjectivesThe aim of this study was to iteratively develop and validate an 18F-labeled small vascular cell adhesion molecule (VCAM)-1 affinity ligand and demonstrate the feasibility of imaging VCAM-1 expression by positron emission tomography–computed tomography (PET-CT) in murine atherosclerotic arteries.BackgroundHybrid PET-CT imaging allows simultaneous assessment of atherosclerotic lesion morphology (CT) and may facilitate early risk assessment in individual patients. The early induction, confinement of expression to atherosclerotic lesions, and accessible position in proximity to the blood pool render the adhesion molecule VCAM-1 an attractive imaging biomarker for inflamed atheroma prone to complication.MethodsA cyclic, a linear, and an oligomer affinity peptide, internalized into endothelial cells by VCAM-1–mediated binding, were initially derivatized with DOTA to determine their binding profiles and pharmacokinetics. The lead compound was then 18F-labeled and tested in atherosclerotic apoE−/− mice receiving a high-cholesterol diet as well as wild type murine models of myocardial infarction and heart transplant rejection.ResultsThe tetrameric peptide had the highest affinity and specificity for VCAM-1 (97% inhibition with soluble VCAM-1 in vitro). In vivo PET-CT imaging using 18F-4V showed 0.31 ± 0.02 SUV in murine atheroma (ex vivo %IDGT 5.9 ± 1.5). 18F-4V uptake colocalized with atherosclerotic plaques on Oil Red O staining and correlated to mRNA levels of VCAM-1 measured by quantitative reverse transcription polymerase chain reaction (R = 0.79, p = 0.03). Atherosclerotic mice receiving an atorvastatin-enriched diet had significantly lower lesional uptake (p < 0.05). Furthermore, 18F-4V imaging in myocardial ischemia after coronary ligation and in transplanted cardiac allografts undergoing rejection showed high in vivo PET signal in inflamed myocardium and good correlation with ex vivo measurement of VCAM-1 mRNA by quantitative polymerase chain reaction.Conclusions 18F-4V allows noninvasive PET-CT imaging of VCAM-1 in inflammatory atherosclerosis, has the dynamic range to quantify treatment effects, and correlates with inflammatory gene expression

Detection of pulse trains in the electrically stimulated cochlea: Effects of cochlear health

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98659/1/JAS003954.pd

Dosimetry of ¹²⁵Iodine protons for in vivo mouse irradiation study

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2006.Includes bibliographical references (leaf 47).The biological effects of acute, high doses of radiation are well understood. However, the effects of chronic, low doses are not as clear. Mice irradiation experiments to study the correlation of biological effects with chronic low dose rates are underway in order to make conclusions about the effects of low doses. Yet, in order to do so, the level of dose provided to the animals must be determined. This paper examines methods of ascertaining the dose rate delivered to mice by photons from an 125Iodine filled flood phantom source. Two distinct methods were used. First, Optically Stimulated Luminescence (OSL) Dosimeters were placed in an array over an area slightly larger than the irradiation area. The dose equivalent they each reported was recorded weekly. Secondly, a series of simulations were performed using MCNP to calculate the expected dose equivalent reported by those dosimeters. Comparison of the dosimeters' recorded dose to MCNP's calculated dose showed agreement within experimental and statistical uncertainty for 82% of the measurements. This high level of agreement demonstrates that the MCNP simulation approach produces reliable results. After this was shown, other MCNP simulations were performed to determine the dose equivalent to the mice in cages placed above the 125I filled phantom. The simulation showed an average dose equivalent of 656 t 108 mrem per week, with a range of 866 t 33 mrem/week to 399 t 18 mrem/week. The dosimetry methods developed in this report are not unique to this dose level, and can be used in future mouse studies to determine dose rates at other orders of magnitude.by Sheena Hembrador.S.B

Development and characterization of a novel variable low-dose rate irradiator for in vivo mouse studies

Radiation exposure of humans generally results in low doses delivered at low dose rate. Our limited knowledge of the biological effects of low dose radiation is mainly based on data from the atomic bomb Life Span Study (LSS) cohort. However, the total doses and dose rates in the LSS cohort are still higher than most environmental and occupational exposures in humans. Importantly, the dose rate is a critical determinant of health risks stemming from radiation exposure. Understanding the shape of the dose-rate response curve for different biological outcomes is thus crucial for projecting the biological hazard from radiation in different environmental and man-made conditions. A significant barrier to performing low dose-rate studies is the difficulty in creating radiation source configurations compatible with long-term cellular or animal experiments. In this study the design and characterization of a large area, 125I-based irradiator is described. The irradiator allows continuous long-term exposure of mice at variable dose rates and can be sited in standard animal care facilities. The dose rate is determined by the level of 125I activity added to a large NaOH-filled rectangular phantom. The desired dose rate is maintained at essentially constant levels by weekly additions of 125I to compensate for decay. Dosimetry results for long-term animal irradiation at targeted dose rates of 0.00021 and 0.0021 cGy min−1 are presented.United States. Dept. of Energy (Grant FG01-04ER04-21)University of California, Davis. Center for Environmental Health Sciences (P30 ES001209-26A1)National Institutes of Health (U.S.) (NIH R01-CA79827)Austrian Academy of Science

Relationship between job satisfaction and work attitude among radiologic technologists in selected hospitals in Cavite

This study used correlational research design using purposive sampling technique. Respondents included 164 radiologic technologists from selected hospitals in Cavite. A two-part questionnaire was used: the first questionnaire is a 36-item job satisfaction survey and the second questionnaire is a 24-item self-made work attitude questionnaire. The data gathered were subjected to statistical treatment such as frequency, percentage, mean, standard deviation, one-way ANOVA, independent t-test and Pearson’s r Correlation Coefficient.Based on the findings of the study, the following conclusions are drawn:1) Half of the respondents have a length of service of 1 to 3 years, most are from level 2 hospitals and worked in more than 2 areas of work; 2) The different facets of job satisfaction including pay, promotion, supervision, fringe benefits, operating conditions, coworkers, nature of work, and communication are ambivalent. The overall job satisfaction of the respondents is ambivalent; 3) The work attitude of the respondents is neutral. Most of the respondents have a neutral work attitude; 4) The job satisfaction of the respondents does not significantly vary when grouped according to the length of service, levels of hospital and their area of work; 5) The work attitude of the respondents does not significantly vary when grouped according to the length of service and their area of work. However, work attitude of the respondents differed when grouped according to the level of hospital. The respondents from level 3 hospital have a better work attitude as compared to level 2 hospital; 6) The job satisfaction and work attitude of the respondents have a moderately small significant positive correlation, with only 6% of the variation of job satisfaction is related to the respondents’ work attitude