Inguinal phlegmon and positive serology for syphilis after penile bite laceration: true, true and unrelated.

Among many causes of penile injury, sexual activity is infrequently reported. The present case involved delay in recognition, which led to development of a phlegmon near major vascular structures. Positive serologic evidence of syphilis was an incidental finding.

Functional MRI in medulloblastoma survivors supports prophylactic reading intervention during tumor treatment.

Development of reading skills is vulnerable to disruption in children treated for brain tumors. Interventions, remedial and prophylactic, are needed to mitigate reading and other learning difficulties faced by survivors. A functional magnetic resonance imaging (fMRI) study was conducted to investigate long-term effects of a prophylactic reading intervention administered during radiation therapy in children treated for medulloblastoma. The fMRI study included 19 reading-intervention (age 11.7 ± 0.6 years) and 21 standard-of-care (age 12.1 ± 0.6 years) medulloblastoma survivors, and 21 typically developing children (age 12.3 ± 0.6 years). The survivors were 2.5 [1.2, 5.4] years after completion of tumor therapies and reading-intervention survivors were 2.9 [1.6, 5.9] years after intervention. Five fMRI tasks (Rapid Automatized Naming, Continuous Performance Test using faces and letters, orthographic and phonological processing of letter pairs, implicit word reading, and story reading) were used to probe reading-related neural activation. Woodcock-Johnson Reading Fluency, Word Attack, and Sound Awareness subtests were used to evaluate reading abilities. At the time of fMRI, Sound Awareness scores were significantly higher in the reading-intervention group than in the standard-of-care group (p = 0.046). Brain activation during the fMRI tasks was detected in left inferior frontal, temporal, ventral occipitotemporal, and subcortical regions, and differed among the groups (p < 0.05, FWE). The pattern of group activation differences, across brain areas and tasks, was a normative trend in the reading-intervention group. Standardized reading scores and patterns of brain activation provide evidence of long-term effects of prophylactic reading intervention in children treated for medulloblastoma.

Changes to collagen structure during leather processing.

As hides and skins are processed to produce leather, chemical and physical changes take place that affect the strength and other physical properties of the material. The structural basis of these changes at the level of the collagen fibrils is not fully understood and forms the basis of this investigation. Synchrotron-based small-angle X-ray scattering (SAXS) is used to quantify fibril orientation and D-spacing through eight stages of processing from fresh green ovine skins to staked dry crust leather. Both the D-spacing and fibril orientation change with processing. The changes in thickness of the leather during processing affect the fibril orientation index (OI) and account for much of the OI differences between process stages. After thickness is accounted for, the main difference in OI is due to the hydration state of the material, with dry materials being less oriented than wet. Similarly significant differences in D-spacing are found at different process stages. These are due also to the moisture content, with dry samples having a smaller D-spacing. This understanding is useful for relating structural changes that occur during different stages of processing to the development of the final physical characteristics of leather.

Clinical utility of the N-back task in functional neuroimaging studies of working memory.

INTRODUCTION: N-back tasks are commonly used in functional neuroimaging studies to identify the neural mechanisms supporting working memory (WM). Despite widespread use, the clinical utility of these tasks is not well specified. This study compared N-back performance during functional magnetic resonance imaging (fMRI) with task data acquired outside of the scanner as a measure of reliability across environment. N-back task validity was examined in relation to performance and rater-based measures used clinically to assess working memory. METHOD: Forty-three healthy adults completed verbal and object N-back tasks during fMRI scanning and outside the scanner. Task difficulty was varied parametrically (0, 1, and 2-back conditions). Order of N-back task completion was stratified by modality (verbal/object) and environment. Participants completed the Digit Span (DS) and provided self-ratings using the Behavior Rating Inventory of Executive Function (BRIEF-WM). RESULTS: Mean verbal and object N-back accuracy was above 95% across load conditions; task difficulty was effectively manipulated across load conditions. Performance accuracy did not significantly differ by environment. N-back reaction time was slower during fMRI (F = 6.52, p = .01, ηp(2) = .13); participants were faster when initially completing tasks outside the scanner (ηp(2) = .10-.15). Verbal 2-back accuracy was significantly related to DS performance (r = .36, p = .02). N-back performance was not related to BRIEF-WM. CONCLUSIONS: Our results provide evidence for reliability of N-back accuracy during fMRI scanning; however, reliability of reaction time data is affected by order of task presentation. Data regarding construct validity are inconsistent and emphasize the need to consider clinical utility of behavioral measures in the design and interpretation of functional neuroimaging studies.

Collagen orientation and leather strength for selected mammals.

Collagen is the main structural component of leather, skin, and some other applications such as medical scaffolds. All of these materials have a mechanical function, so the manner in which collagen provides them with their strength is of fundamental importance and was investigated here. This study shows that the tear strength of leather across seven species of mammals depends on the degree to which collagen fibrils are aligned in the plane of the tissue. Tear-resistant material has the fibrils contained within parallel planes with little crossover between the top and bottom surfaces. The fibril orientation is observed using small-angle X-ray scattering in leather, produced from skin, with tear strengths (normalized for thickness) of 20-110 N/mm. The orientation index, 0.420-0.633, is linearly related to tear strength such that greater alignment within the plane of the tissue results in stronger material. The statistical confidence and diversity of animals suggest that this is a fundamental determinant of strength in tissue. This insight is valuable in understanding the performance of leather and skin in biological and industrial applications.

Collagen fibril alignment and deformation during tensile strain of leather: a small-angle X-ray scattering study.

The distribution and effect of applied strain on the collagen fibrils that make up leather may have an important bearing on the ultimate strength and other physical properties of the material. While sections of ovine and bovine leather were being subjected to tensile strain up to rupture, synchrotron-based small-angle X-ray scattering (SAXS) spectra were recorded edge-on to the leather at points from the corium to the grain. Measurements of both fibril orientation and collagen d spacing showed that, initially, the fibers reorient under strain, becoming more aligned. As the strain increases (5-10% strain), further fibril reorientation diminishes until, at 37% strain, the d spacing increases by up to 0.56%, indicating that significant tensile forces are being transmitted to individual fibrils. These changes, however, are not uniform through the cross-section of leather and differ between leathers of different strengths. The stresses are taken up more evenly through the leather cross-section in stronger leathers in comparison to weaker leathers, where stresses tended to be concentrated during strain. These observations contribute to our understanding of the internal strains and structural changes that take place in leather under stress.

Collagen fibril orientation in ovine and bovine leather affects strength: a small angle X-ray scattering (SAXS) study.

There is a large difference in strength between ovine and bovine leather. The structure and arrangement of fibrous collagen in leather and the relationship between collagen structure and leather strength has until now been poorly understood. Synchrotron based SAXS is used to characterize the fibrous collagen structure in a series of ovine and bovine leathers and to relate it to tear strength. SAXS gives quantitative information on the amount of fibrous collagen, the orientation (direction and spread) of the collagen microfibrils, and the d-spacing of the collagen. The amount of collagen varies through the thickness of the leather from the grain to the corium, with a greater concentration of crystalline collagen measured toward the corium side. The orientation index (OI) is correlated strongly with strength in ovine leather and between ovine and bovine leathers. Stronger leather has the fibrils arranged mostly parallel to the plane of the leather surface (high OI), while weaker leather has more out-of-plane fibrils (low OI). With the measurement taken parallel to the animal's backbone, weak (19.9 N/mm) ovine leather has an OI of 0.422 (0.033), stronger (39.5 N/mm) ovine leather has an OI of 0.452 (0.033), and bovine leather with a strength of (61.5 N/mm) has an OI of 0.493 (0.016). The d-spacing profile through leather thickness also varies according to leather strength, with little variation being detected in weak ovine leather (average=64.3 (0.5) nm), but with strong ovine leather and bovine leather (which is even stronger) exhibiting a dip in d-spacing (from 64.5 nm at the edges dropping to 62 nm in the center). This work provides a clear understanding of a nanostructural characteristic of ovine and bovine leather that leads to differences in strength.

Biophysical characterization of ovine forestomach extracellular matrix biomaterials.

Ovine forestomach matrix (OFM) is a native and functional decellularized extracellular matrix biomaterial that supports cell adhesion and proliferation and is remodeled during the course of tissue regeneration. Small angle X-ray scattering demonstrated that OFM retains a native collagen architecture (d spacing = 63.5 ± 0.2 nm, orientation index = 20°). The biophysical properties of OFM were further defined using ball-burst, uniaxial and suture retention testing, as well as a quantification of aqueous permeability. OFM biomaterial was relatively strong (yield stress = 10.15 ± 1.81 MPa) and elastic (modulus = 0.044 ± 0.009 GPa). Lamination was used to generate new OFM-based biomaterials with a range of biophysical properties. The resultant multi-ply OFM biomaterials had suitable biophysical characteristics for clinical applications where the grafted biomaterial is under load.

Leather structure determination by small-angle X-ray scattering (SAXS): cross sections of ovine and bovine leather.

SAXS has been applied to structural determination in leather. The SAXS beamline at the Australian Synchrotron provides 6 orders of magnitude dynamic range, enabling a rich source of structural information from scattering patterns of leather sections. SAXS patterns were recorded for q from 0.004 to 0.223 A(-1). Collagen d spacing varied across ovine leather sections from 63.8 nm in parts of the corium up to 64.6 nm in parts of the grain. The intensity of the collagen peak at q = 0.06 A(-1) varied by 1 order of magnitude across ovine leather sections with the high-intensity region in the corium and the low intensity in the grain. The degree of fiber orientation and the dispersion of the orientation has been quantified in leather. It is shown how the technique provides a wealth of useful information that may be used to characterize and compare leathers, skin, and connective tissue.