Effects of immobilization on articular cartilage: Autohistoradiographic findings with S35

The effect of immobilization on the articular cartilage of rabbits was studied by light microscope. The knee joint of each rabbit was immobilized in a plaster in a position midway between flexion and extension for a 10 to 120 days period. Degenerative changes in the articular cartilage of increasing severity were observed. The fixation of the labeled SO4 by cartilage cells was decreased in advanced immobilization

Single-image measurements of monochromatic subdiffraction dimolecular separations

Measuring subdiffraction separations between single fluorescent particles is important for biological, nano-, and medical-technology studies. Major challenges include (i) measuring changing molecular separations with high temporal resolution while (ii) using identical fluorescent labels. Here we report a method that measures subdiffraction separations between two identical fluorophores by using a single image of milliseconds exposure time and a standard single-molecule fluorescent imaging setup. The fluorophores do not need to be bleached and the separations can be measured down to 40 nm with nanometer precision. The method is called single-molecule image deconvolution -- SMID, and in this article it measures the standard deviation (SD) of Gaussian-approximated combined fluorescent intensity profiles of the two subdiffraction-separated fluorophores. This study enables measurements of (i) subdiffraction dimolecular separations using a single image, lifting the temporal resolution of seconds to milliseconds, while (ii) using identical fluorophores. The single-image nature of this dimer separation study makes it a single-image molecular analysis (SIMA) study.Comment: 16 pages, 5 figure

Image Deconvolution Techniques for Single Molecule Studies

One of the principal challenges in the field of biophysics, particularly that of protein-nucleic acid interactions, is the need to analyze information from single proteins as opposed to ensembles of many molecules. Consequently, the advent of high-resolution imaging in single molecule microscopy has enabled researchers to probe the underlying processes of gene regulatory networks and other biological systems. There is, nonetheless, a tradeoff between spatial and temporal resolution, or the ability to localize a molecule in space at increasingly shorter time scales. As such, this dissertation addresses these challenges that hinder single molecule studies by:: i) developing deconvolution techniques in order to localize both immobile and dynamic molecules from their single images with improved spatial and temporal resolution,: ii) determining a protein\u27s diffusive properties with high temporal resolution, and: iii) applying our analytical methods to study model biological systems

Label‐free detection and manipulation of single biological nanoparticles

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134272/1/wnan1392.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134272/2/wnan1392_am.pd

Protein sliding and hopping kinetics on DNA

Using Monte-Carlo simulations, we deconvolved the sliding and hopping kinetics of GFP-LacI proteins on elongated DNA from their experimentally observed seconds-long diffusion trajectories. Our simulations suggest the following results: (1) in each diffusion trajectory, a protein makes on average hundreds of alternating slides and hops with a mean sliding time of several tens of ms; (2) sliding dominates the root mean square displacement of fast diffusion trajectories, whereas hopping dominates slow ones; (3) flow and variations in salt concentration have limited effects on hopping kinetics, while in vivo DNA configuration is not expected to influence sliding kinetics; furthermore, (4) the rate of occurrence for hops longer than 200 nm agrees with experimental data for EcoRV proteins

The Jefferson Scale of Empathy: a nationwide study of measurement properties, underlying components, latent variable structure, and national norms in medical students.

The Jefferson Scale of Empathy (JSE) is a broadly used instrument developed to measure empathy in the context of health professions education and patient care. Evidence in support of psychometrics of the JSE has been reported in health professions students and practitioners with the exception of osteopathic medical students. This study was designed to examine measurement properties, underlying components, and latent variable structure of the JSE in a nationwide sample of first-year matriculants at U.S. colleges of osteopathic medicine, and to develop a national norm table for the assessment of JSE scores. A web-based survey was administered at the beginning of the 2017-2018 academic year which included the JSE, a scale to detect good impression responses, and demographic/background information. Usable surveys were received from 6009 students enrolled in 41 college campuses (median response rate = 92%). The JSE mean score and standard deviation for the sample were 116.54 and 10.85, respectively. Item-total score correlations were positive and statistically significant (p \u3c 0.01), and Cronbach α = 0.82. Significant gender differences were observed on the JSE scores in favor of women. Also, significant differences were found on item scores between top and bottom third scorers on the JSE. Three factors of Perspective Taking, Compassionate Care, and Walking in Patient\u27s Shoes emerged in an exploratory factor analysis by using half of the sample. Results of confirmatory factor analysis with another half of the sample confirmed the 3-factor model. We also developed a national norm table which is the first to assess students\u27 JSE scores against national data

The Test- Retest Reliability and Minimal Detectable Change of the Sensory Organization Test and Head- Shake Sensory Organization Test

Context: The assessment of balance deficits following sport- related concussion can be accomplished using computerized dynamic posturography (CDP) testing procedures, including the Sensory Organization Test (SOT) and the Head- Shake Sensory Organization Test (HS- SOT). Although these tests are considered to be important post- concussion balance assessments, the test- retest reliability of the HS- SOT has not been evaluated in a healthy, athletic population. Objective: Our purpose was to evaluate the test- retest reliability of the HS-SOT in a non-concussed, athletic sample. Design: A prospective, time series, cohort design was used. Setting: University research laboratory. Participants or Other Participants: Twenty (8 F, 12 M) healthy intercollegiate athletes (age 19.95 ± 1.28 years, height 175.55 ± 13.57 cm, weight 74.73 ± 17.59 kg). Interventions: Postural stability was assessed at two time intervals (9 days apart). Subjects completed all 6 testing conditions of the SOT and the 2 testing conditions for the HS- SOT. Results: Excellent test- retest reliability was demonstrated for the SOT composite equilibrium scores (ICC 1,1= .83). Moderate test- retest reliability was observed for the SOT equilibrium scores for conditions 2 (.66) and 5 (.65); somatic (.58), visual (.65), and vestibular sensory analyses (.68); and sensory analysis preference (.66). Moderate reliability was also noted for equilibrium scores on condition 5 for the HS- SOT (.65). The test- retest reliability was poor for the HS- SOT equilibrium scores on condition 2 (ICC= .26, δ2= .14), HS-SOT equilibrium score ratio for fixed surface (ICC= .37, δ2 2= .003). Conclusions: Determining the minimal difference in HS- SOT scores (ICC and MDC) representing significant change over time will help clinicians to identify athletes with balance disorders in the acute post- concussion phase

Use of differential scanning fluorimetry as a high-throughput assay to identify nuclear receptor ligands

Identification of ligands that interact with nuclear receptors is both a major biological problem and an important initial step in drug discovery. Several in vitro and in vivo techniques are commonly used to screen ligand candidates against nuclear receptors; however, none of the current assays allow screening without modification of either the protein and/or the ligand in a high-throughput fashion. Differential scanning fluorimetry (DSF) allows unmodified potential ligands to be screened as 10µL reactions in 96-well format against partially purified protein, revealing specific interactors. As a proof of principle, we used a commercially-available nuclear receptor ligand candidate chemical library to identify interactors of the human estrogen receptor α ligand binding domain (ERα LBD). Compounds that interact specifically with ERα LBD stabilize the protein and result in an elevation of the thermal denaturation point, as monitored by the environmentally-sensitive dye SYPRO orange. We successfully identified all three compounds in the library that have previously been identified to interact with ERα, with no false positive results

Clarifying Relationships Between Cranial Form and Function in Tapirs, With Implications for the Dietary Ecology of Early Hominins

Paleontologists and paleoanthropologists have long debated relationships between cranial morphology and diet in a broad diversity of organisms. While the presence of larger temporalis muscle attachment area (via the presence of sagittal crests) in carnivorans is correlated with durophagy (i.e. hard-object feeding), many primates with similar morphologies consume an array of tough and hard foods—complicating dietary inferences of early hominins. We posit that tapirs, large herbivorous mammals showing variable sagittal crest development across species, are ideal models for examining correlations between textural properties of food and sagittal crest morphology. Here, we integrate dietary data, dental microwear texture analysis, and finite element analysis to clarify the functional significance of the sagittal crest in tapirs. Most notably, pronounced sagittal crests are negatively correlated with hard-object feeding in extant, and several extinct, tapirs and can actually increase stress and strain energy. Collectively, these data suggest that musculature associated with pronounced sagittal crests—and accompanied increases in muscle volume—assists with the processing of tough food items in tapirs and may yield similar benefits in other mammals including early hominins