The WRAIR Projectile Concussive Impact Model of Mild Traumatic Brain Injury: Re-design,Testing and Preclinical Validation

The WRAIR projectile concussive impact (PCI) model was developed for preclinical study of concussion. It represents a truly non-invasive closed-head injury caused by a blunt impact. The original design, however, has several drawbacks that limit the manipulation of injury parameters. The present study describes engineering advancements made to the PCI injury model including helmet material testing, projectile impact energy/head kinematics and impact location. Material testing indicated that among the tested materials, ‘fiber-glass/carbon’ had the lowest elastic modulus and yield stress for providing an relative high percentage of load transfer from the projectile impact, resulting in significant hippocampal astrocyte activation. Impact energy testing of small projectiles, ranging in shape and size, showed the steel sphere produced the highest impact energy and the most consistent impact characteristics. Additional tests confirmed the steel sphere produced linear and rotational motions on the rat’s head while remaining within a range that meets the criteria for mTBI. Finally, impact location testing results showed that PCI targeted at the temporoparietal surface of the rat head produced the most prominent gait abnormalities. Using the parameters defined above, pilot studies were conducted to provide initial validation of the PCI model demonstrating quantifiable and significant increases in righting reflex recovery time, axonal damage and astrocyte activation following single and multiple concussions.     

DCE‐MRI findings of invasive aspergillosis in patient with acute myeloid leukemia

Thoracic radiography and high resolution computerized tomography is used to diagnose pulmonary infections in immunosuppressed patients, although in some cases these do not provide enough information about the lesion. Dynamic contrast‐enhanced magnetic resonance imaging may be useful in these cases, especially for the characterization of cavitary lesions and assessment of their contrast diffusion.     

Heme-protein vibrational couplings in cytochrome c provide a dynamic link that connects the heme-iron and the protein surface

The active site of cytochrome c (Cyt c) consists of a heme covalently linked to a pentapeptide segment (Cys-X-X-Cys-His), which provides a link between the heme and the protein surface, where the redox partners of Cyt c bind. To elucidate the vibrational properties of heme c, nuclear resonance vibrational spectroscopy (NRVS) measurements were performed on (57)Fe-labeled ferric Hydrogenobacter thermophilus cytochrome c(552), including (13)C(8)-heme-, (13)C(5)(15)N-Met-, and (13)C(15)N-polypeptide (pp)-labeled samples, revealing heme-based vibrational modes in the 200- to 450-cm(-1) spectral region. Simulations of the NRVS spectra of H. thermophilus cytochrome c(552) allowed for a complete assignment of the Fe vibrational spectrum of the protein-bound heme, as well as the quantitative determination of the amount of mixing between local heme vibrations and pp modes from the Cys-X-X-Cys-His motif. These results provide the basis to propose that heme-pp vibrational dynamic couplings play a role in electron transfer (ET) by coupling vibrations of the heme directly to vibrations of the pp at the protein-protein interface. This could allow for the direct transduction of the thermal (vibrational) energy from the protein surface to the heme that is released on protein/protein complex formation, or it could modulate the heme vibrations in the protein/protein complex to minimize reorganization energy. Both mechanisms lower energy barriers for ET. Notably, the conformation of the distal Met side chain is fine-tuned in the protein to localize heme-pp mixed vibrations within the 250- to 400-cm(-1) spectral region. These findings point to a particular orientation of the distal Met that maximizes ET.     

Inhibition of cell survival, viability and proliferation by dentin adhesives after direct and indirect exposure in vitro

Objectives

The influence of dentin adhesive systems (Scotchbond Multi-Purpose, XP Bond, Xeno V, Clearfil Protect Bond, AdheSE) on cell survival, viability and proliferation was characterized after direct and indirect exposure using different cell culture techniques.

Materials and methods

The primers and cured bonding parts were directly exposed to cells using cell culture inserts, and complete materials were analyzed in a dentin barrier test. Cell responses were examined in 3T3 mouse fibroblasts after 24- and 72-h exposure periods by the estimation of total cell numbers (survival), apoptosis (viability) and cell proliferation.

Results

Cell numbers were effectively reduced by the primers of AdheSE, Protect Bond, and Scotchbond Multi-Purpose as well as XP bond after direct exposure in a cell culture insert test device. Likewise, Scotchbond Multi-Purpose primer induced a rate of apoptosis (93.9%) even higher than detected with Protect Bond primer (91.6%). Cell proliferation was entirely inhibited by primers and by Xp Bond as well. The Scotchbond Multi-Purpose was most cytotoxic in a dentin barrier test device after a 24-h indirect exposure. It also increased the percentage of cells in apoptosis to 15.4% compared to untreated controls.

Conclusion

Unpolymerized primers of dentin adhesives were more cytotoxic than polymerized bonding counterparts. Moreover, total etch dentin adhesives were more cytotoxic than self-etch adhesives.

Clinical relevance

When dentin adhesives are used in deep cavities without a protective dentin barrier the leachable hydrophobic and hydrophilic component of dentin adhesive systems can penetrate to the pulp and may induce cytotoxic responses in pulp tissues.     

Segmental vitiligo in a patient with thoracic outlet syndrome

Reported here is a 35-year-old man with findings of thoracic outlet syndrome and bilateral segmental vitiligo on C8–T1 dermatomes. The possible causal relationship between the two disorders under the common denominator of cervical sympathetic involvement is discussed for the first time in the literature.     

A dance program to improve gait and balance in individuals with chronic stroke: a feasibility study

Background and Objective Despite gains made with rehabilitation, gait and balance remain limited post-stroke. Dance is a fun and motivating activity which has shown benefits in individuals with Parkinson’s disease. The purpose of this article is to investigate the feasibility of a dance program for individuals with chronic stroke.

Methods Pre-post intervention feasibility study where twenty individuals with chronic stroke participated in a dance class twice a week for 10 weeks. Feasibility measures included interest, enrollment, attendance, adverse events, and participant satisfaction. Outcomes of interest were spatiotemporal gait parameters and balance assessed with the MiniBESTest before and after the dance program. Pre and post measures were compared with paired t-tests.

Results Of the 33 individuals approached, 30 (90.9%) were interested in participating; however, scheduling conflicts were a common barrier. Ultimately, 22 individuals consented and 20 individuals completed the dance program without adverse events. The mean age was 62.3 (10.4) years, time post-stroke was 6.4 (6.0) years and National Institutes of Health Stroke Scale score was 3.1 (2.0). Average attendance was 92.5% with 10 classes missed across 8 participants and satisfaction ratings were high (e.g. 17/20 strongly agreed they enjoyed the program). No significant differences in spatiotemporal gait parameters were found; however, MiniBESTest scores significantly increased from 16.5 (6.0) to 18.6 (4.9) (p = 0.0005).

Discussion and Conclusions A dance program is safe and feasible post-stroke. Attendance and satisfaction were high and participants perceived walking and balance benefits. Future work will include a randomized controlled trial.     

Utility of the Rey-15 Recognition Trial to Detect Invalid Performance in a Forensic Neuropsychological Sample

The current study sought to address the utility of the Rey Fifteen Item Test (Rey-15), with the use of a combined score [recall correct + (recognition correct – false positives)], to distinguish between valid and invalid performance among a sample of litigating persons referred for neuropsychological evaluation. Scores on the Rey-15 were analyzed across four comparison groups: (1) litigating persons with evidence of invalid performance (n = 29), (2) litigating persons with valid performance (n = 63), (3) learning-disabled patients (n = 36), and (4) a mixed clinical neuropsychological sample not involved in litigation (n = 54). A Rey-15 combined cutoff score of < 21 yielded the highest sensitivity (70%) and specificity (92.8%) rates. If the Rey-15 is to be used in clinical practice to detect invalid performance, the recognition trial with combined score < 21 should be used. Findings support the use of the combined Rey-15 score in place of the previously used recall Rey-15 score to improve sensitivity and specificity rates for detection of invalid performance in litigating neuropsychological referrals.