Boston University

About: Boston University is a education organization based out in Boston, Massachusetts, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 48688 authors who have published 119622 publications receiving 6276020 citations. The organization is also known as: BU & Boston U.

Vaginal progesterone reduces the rate of preterm birth in women with a sonographic short cervix: a multicenter, randomized, double-blind, placebo-controlled trial

Abstract: Objectives Women with a sonographic short cervix in the mid-trimester are at increased risk for preterm delivery. This study was undertaken to determine the efficacy and safety of using micronized vaginal progesterone gel to reduce the risk of preterm birth and associated neonatal complications in women with a sonographic short cervix. Methods This was a multicenter, randomized, doubleblind, placebo-controlled trial that enrolled asymptomatic

TLR4, but not TLR2, mediates IFN-beta-induced STAT1alpha/beta-dependent gene expression in macrophages.

Abstract: Toll-like receptor 2 (TLR2) agonists induce a subset of TLR4-inducible proinflammatory genes, which suggests the use of differential signaling pathways. Murine macrophages stimulated with the TLR4 agonist Escherichia coli lipopolysaccharide (LPS), but not with TLR2 agonists, induced phosphorylation of signal transducer and activator of transcription 1alpha (STAT1alpha) and STAT1beta, which was blocked by antibodies to interferon beta (IFN-beta) but not IFN-alpha. All TLR2 agonists poorly induced IFN-beta, which is encoded by an immediate early LPS-inducible gene. Thus, the failure of TLR2 agonists to induce STAT1-dependent genes resulted, in part, from their inability to express IFN-beta. TLR4-induced IFN-beta mRNA was MyD88- and PKR (double-stranded RNA-dependent protein kinase)-independent, but TIRAP (Toll-interleukin 1 receptor domain-containing adapter protein)-dependent. Together, these findings provide the first mechanistic basis for differential patterns of gene expression activated by TLR4 and TLR2 agonists.

X-ray-Computed Tomography Contrast Agents

Abstract: X-ray computed tomography (CT) is a well-established tissue imaging technique employed in a variety of research and clinical settings.1 Specifically, CT is a non-invasive clinical diagnostic tool that allows for 3D visual reconstruction and segmentation of tissues of interest. High resolution CT systems can be used to perform non-destructive 3D imaging of a variety of tissue types and organ systems, such as: the gastrointestinal tract, cardiovascular system, renal tract, liver, lungs, bone, cartilage, tumorous tissue, etc. CT is one of the most prevalent diagnostic tools in terms of frequency-of-use and hospital availability.2 The use of CT is on the rise and the number of clinical CT scanners in operation worldwide is estimated at over 45,000.1b Today, over 70 million clinical CT scans are performed yearly in the U.S. alone. For a recent detailed analysis of the use of clinical CT imaging and data regarding the number of regular and contrast-enhanced CT scans performed annually in the U.S. we refer the reader to the “Nationwide Evaluation of X-ray Trends” survey published by the Conference for Radiation Control Program Directors (CRCPD).3 The idea of using tomography (Greek: tomos = slice, graphein = draw) as a diagnostic tool in medicine was adopted soon after the discovery of X-rays by W. C. Roentgen in 1895. However, several more decades passed before the technology advanced sufficiently to bring those ideas to fruition. The first successful CT imaging device was built in 1972 by G. N. Hounsfield, at Electric and Musical Industries Ltd. In 1979, G. N. Hounsfield and South African physicist A. M. Cormack shared a Nobel Prize in medicine for their contributions to the field of X-ray CT imaging and diagnostics.4 X-rays are a form of electromagnetic radiation with wavelengths roughly between 0.01 nm and 10 nm. Traditionally, X-rays are generated by a vacuum tube using high voltage to accelerate electrons from a cathode to a (usually) tungsten-alloy anode. In the process, the accelerated electrons release electromagnetic radiation in the form of X-rays and the maximum energy of the radiation is limited by the energy of the incident electron. Operating voltages of modern clinical CT scanners differ among instrument models and manufacturers, but generally fall between 80 kVp to 150 kVp. As a rule, materials possessing higher density (ρ) or high atomic number (Z) tend to better absorb X-rays. The relationship is best expressed in the formula for X-ray absorption coefficient (μ): μ≈ρZ4AE3 (1) where “A” is the atomic mass and “E” is the X-ray energy. The strong relationship between absorption and atomic number is of significant importance in clinical applications. The Z4 factor allows for contrast levels of several orders of magnitude between different tissues and types of contrast agents. When an incident X-ray has energy equal or slightly greater than the binding energy of the K-shell electron of the atom, a large sudden increase in absorption coefficient is observed. This energy value is known as absorption edge (k), and the k value increases with atomic number of the element. Consequently, X-ray attenuating contrast media containing atoms of high atomic number (most commonly iodine or barium), are frequently used in clinical settings to obtain images of soft tissues. To generate images with the highest contrast to the surrounding tissue, the energy of the X-ray source can be adjusted to closely match the absorption edge value (k) of the relevant imaging-agent atoms (i.e., iodine, barium, gold, etc.). Thus, it is also possible to do selective X-ray imaging and to differentiate between attenuating materials by fine tuning the energy source to the appropriate absorption edge value. A CT image is obtained by rotating an X-ray source around an object, with a detector positioned directly opposite the radiation source. Alternatively, in many preclinical CT scanners the object sometimes is rotated around its own axis. Such preclinical scanners are often being used for small animal in vivo imaging. Generally, X-ray scans are taken at small angular increments during rotation around the object over 360°. A series of attenuation profiles or projections is thus obtained. The projections are then processed mathematically to create a 3D rendition of the scanned object. An in depth description of the engineering principles underlying modern CT imaging instruments is beyond the scope of this manuscript, and the reader is referred to other published works.1c,5 A diagnostic imaging method related to CT is X-ray fluoroscopy. Fluoroscopy allows for the acquisition of real-time, continuous images of the internal organs. Like in CT, imaging agents are often used in fluoroscopy for better contrast resolution. Small iodinated agents are commonly injected into blood vessels for use in fluoroscopic angiography, allowing for the evaluation of blood flow and visualization of the vasculature system, while barium contrast media are introduced orally or with an enema to investigate the anatomy (and pathology) of the gastrointestinal tract. The introduction of magnetic resonance imaging (MRI) resulted in a loss of interest and reduction in CT contrast agent development throughout the 1980s. However, advances in computer technology, and the introduction and widespread adoption of spiral-CT in the mid-1990s have sparked a revival of interest in CT imaging and CT contrast media. Current clinical CT scanners are capable of acquiring high resolution 3D isotropic images of the body within several minutes. CT imaging today is less time consuming, less expensive, and more readily available than other medical imaging technologies such as MRI and positron emission tomography (PET). In the last several years, the emergence of novel technologies such as dual-source CT, and multi-detector CT has advanced the field of CT imaging even further. As a comparison to X-ray imaging diagnostic methods, PET imaging employs gamma-ray emitting radioactive nuclei “tracers” as contrast agents while MRI takes advantage of nuclear magnetic resonance principles by applying high magnetic fields to align magnetization of certain atomic nuclei. In contrast to CT and PET imaging, MRI uses no ionizing radiation and it is therefore often deemed safer than the other two.

Molecular Fluorescence and Energy Transfer Near Interfaces

Abstract: Summary This chapter contains sections titled: Introduction Dipole Emission Near Interfaces Dyadic Green's Function Method Energy Transfer and Surface Plasmons Summary

DNA methylation-based measures of biological age: meta-analysis predicting time to death

Abstract: Estimates of biological age based on DNA methylation patterns, often referred to as "epigenetic age", "DNAm age", have been shown to be robust biomarkers of age in humans. We previously demonstrated that independent of chronological age, epigenetic age assessed in blood predicted all-cause mortality in four human cohorts. Here, we expanded our original observation to 13 different cohorts for a total sample size of 13,089 individuals, including three racial/ethnic groups. In addition, we examined whether incorporating information on blood cell composition into the epigenetic age metrics improves their predictive power for mortality. All considered measures of epigenetic age acceleration were predictive of mortality (p≤8.2x10-9), independent of chronological age, even after adjusting for additional risk factors (p<5.4x10-4), and within the racial/ethnic groups that we examined (non-Hispanic whites, Hispanics, African Americans). Epigenetic age estimates that incorporated information on blood cell composition led to the smallest p-values for time to death (p=7.5x10-43). Overall, this study a) strengthens the evidence that epigenetic age predicts all-cause mortality above and beyond chronological age and traditional risk factors, and b) demonstrates that epigenetic age estimates that incorporate information on blood cell counts lead to highly significant associations with all-cause mortality.