Structural response and relative strength of a laminated composite hip prosthesis: effects of functional activity

To obtain a better appreciation for the structural performance of a laminated composite hip prosthesis (CP), we examined in situ prosthesis structural response and relative strengths as a function of walking and stair climbing using our previously developed analysis guidelines. Accordingly, we examined overall prosthesis structural response utilizing a global continuum level modeling approach and prosthesis relative strengths using a local microstructural (or ply-level) modeling approach. As a reference and control, we examined the structural performance of the intact natural femur (NAT) and a titanium alloy (Ti) based hip prosthesis. In terms of the overall structural response, i.e., the femur/prosthesis deformational response, stem/bone interfacial stress transfer, and calcar strain energy density restored, the performance of the CP prosthesis was moderately improved over that of the control Ti prosthesis and better approximates the NAT response. In terms of relative strength, we found that the neck of the CP prosthesis failed for all activities with the exception of the mid-stance phase of level walking. However, the prosthesis appears to have sufficient relative strength for function at positions distal to the neck of the prosthesis. While these results dampen enthusiasm for consideration of laminated composite hip prostheses designed with a shape based on a metal alloy implant, they indirectly support consideration of alternate hip prosthesis structural designs such as using a better supported prosthesis neck or utilizing metal/composite hybrid constructions. Importantly, our simulation and analysis approach could be utilized in the design of other laminated composite biomedical structural components.     

Cytopathology of uncommon malignant renal neoplasms in the pediatric age group

Malignant renal neoplasms are common solid tumors in pediatric oncology practice. These include the common Wilms' tumor/nephroblastoma and the uncommon neoplasms such as clear-cell sarcoma of the kidney (CCSK), rhabdoid tumor, renal-cell carcinoma, and others. The aim of this study was to describe in detail the cytopathological features of the histopathologically proven uncommon pediatric renal tumors. Aspirates from Wilms' tumor, which are mesenchyme predominant, show clusters of spindle cells associated with the matrix material. Evidence of rhabdomyoblastic differentiation may be present. CCSK, classic subtype, is characterized by round to oval cells arranged perivascularly and also in sheets and clusters intimately associated with a metachromatic matrix mucopolysaccharide material better appreciated in May-Grunwald-Giemsa (MGG)-stained smears. The cells also have more abundant cytoplasm and may show nuclear grooves. Spindle-cell pattern of CCSK is difficult to diagnose on aspiration cytology. Renal-cell carcinoma of childhood shows similar cytological features as its adult counterpart. Rhabdoid tumor of the kidney is characterized by a monomorphic population of cells with abundant cytoplasm, eccentric nuclei with prominent nucleoli. Intrarenal yolk sac tumor is a rare neoplasm and shows severely pleomorphic cells on aspiration.Awareness of these entities is important for the practicing cytopathologist. Further, non-Wilms' renal malignant neoplasms must be distinguished from the common Wilms' tumor so that appropriate chemotherapy protocols may be instituted in cases where the tumor is in an advanced stage of malignancy.     

Healthy monozygous twins do not recognize identical T cell epitopes on the myelin basic protein autoantigen

The T cell response against myelin basic protein (MBP) has been extensively studied in humans because of its putative role in the pathophysiology of multiple sclerosis (MS). Higher concordance rates in monozygous twins as well as an increased risk in relatives suggest the role of genetic factors in MS susceptibility. Very little is known about the shaping of T cell repertoire towards self antigens in humans and their contribution to disease susceptibility in autoimmune disorders. Here we report the comparative T cell epitope recognition patterns towards the MBP auto-antigen in healthy identical twins. We have established MBP-specific T cell lines from eight sets of twins and characterized their fine epitope specificity. Intra-pair comparison showed the co-existence of shared as well as distinct epitopes in six of eight pairs and a complete absence of concordant epitope recognition within two other pairs. These findings indicate that important differences in T cell repertoires against a self antigen may be observed between genetically identical healthy individuals, rendering difficult the interpretation of the differences which may be observed between identical twins discordant for an autoimmune disease.     

Primary papillary carcinoma of the thyroglossal duct cyst--a case report

Thyroglossal duct cyst is the most common developmental anomaly of the thyroid gland, presenting as a mid line neck swelling. Malignancy arising in them is a rare event, with papillary thyroid carcinoma being the commonest. Thyroglossal duct cyst carcinomas are usually asymptomatic and are not suspected preoperatively in most instances, hence the need for surgical excision and careful pathological examination of these cysts. We present a case of a 57 year old lady who underwent a Sistrunk procedure for the removal of thyroglossal duct cyst, which was responsible for a progressive mid line neck swelling of 2 months duration. The thyroid gland was normal. Histological examination of the excised cyst showed a papillary thyroid carcinoma arising in the thyroglossal duct cyst. Long term survival of patients with thyroglossal duct cyst carcinoma is excellent.     

Tactile discrimination of shape: responses of rapidly adapting mechanoreceptive afferents to a step stroked across the monkey fingerpad

Responses of rapidly adapting Meissner corpuscle mechanoreceptive afferent fibers (RAs) to steps of varying shape stroked across the distal fingerpad were recorded from anesthetized monkeys. A series of flat plates were used, each having an increase in thickness (a step) in the middle so that one-half of the plate was thicker than the other. The cross-sectional shape of the step approximated that of a half-cycle sinusoid, 0.5 mm high. The width (half-cycle wavelength) of the sinusoidal step was varied from 0 to 3.13 mm, producing a series of step shapes that differed in steepness and curvature. These steps could be broadly categorized into 2 groups, "steep" and "gradual." Each step was stroked back and forth under constant compressional force, using a servocontrolled mechanical stimulator. The RA's response to a step provided a spatial pattern of action potentials in which the occurrence of each impulse corresponded to a position of the step on the skin. This response consisted of a single "burst" of impulses to the sinusoidal portion of the step. Changes in stroke direction, step shape, or velocity of stroking primarily affected the RA discharge rate during the burst, and, less consistently, the spatial width of the burst. For a given step shape and stroke velocity, the discharge rate was greater for strokes from the low to the high side of the step than for strokes from the high to the low side. Discharge rate was greater for steep than for gradual steps and, for a given step, it increased with stroke velocity. All the major features of the responses were interpreted as being due predominantly to the sensitivity of the RA to vertical velocity at the most sensitive spot on its receptive field, together with a sensitivity to the rate of change in skin curvature at that spot. RA discharge rate distinguished not only the gross differences between steep and gradual steps, but also some of the finer differences in sharpness among steep steps. From a comparison with the human capacity for tactile discrimination of the steps, it was concluded that RAs, through their discharge rates, provide primarily "intensive" information about the sharpness of shapes.     

Interventions to Increase Multivitamin Use Among Women in the Interconception Period: An IMPLICIT Network Study

Maternal and Child Health Journal - Each year, 3% of infants in the Unites States (US) are born with congenital anomalies, including 3000 with neural tube defects. Multivitamins (MVIs) including...     

The First Genome-Wide Association Study for Type 2 Diabetes in Youth: The Progress in Diabetes Genetics in Youth (ProDiGY) Consortium

The prevalence of type 2 diabetes in youth has increased substantially, yet the genetic underpinnings remain largely unexplored. To identify genetic variants predisposing to youth-onset type 2 diabetes, we formed ProDiGY, a multiethnic collaboration of three studies (TODAY, SEARCH, and T2D-GENES) with 3,006 youth case subjects with type 2 diabetes (mean age 15.1 ± 2.9 years) and 6,061 diabetes-free adult control subjects (mean age 54.2 ± 12.4 years). After stratifying by principal component–clustered ethnicity, we performed association analyses on ∼10 million imputed variants using a generalized linear mixed model incorporating a genetic relationship matrix to account for population structure and adjusting for sex. We identified seven genome-wide significant loci, including the novel locus rs10992863 in PHF2 (P = 3.2 × 10⁻⁸; odds ratio [OR] = 1.23). Known loci identified in our analysis include rs7903146 in TCF7L2 (P = 8.0 × 10⁻²⁰; OR 1.58), rs72982988 near MC4R (P = 4.4 × 10⁻¹⁴; OR 1.53), rs200893788 in CDC123 (P = 1.1 × 10⁻¹²; OR 1.32), rs2237892 in KCNQ1 (P = 4.8 × 10⁻¹¹; OR 1.59), rs937589119 in IGF2BP2 (P = 3.1 × 10⁻⁹; OR 1.34), and rs113748381 in SLC16A11 (P = 4.1 × 10⁻⁸; OR 1.04). Secondary analysis with 856 diabetes-free youth control subjects uncovered an additional locus in CPEB2 (P = 3.2 × 10⁻⁸; OR 2.1) and consistent direction of effect for diabetes risk. In conclusion, we identified both known and novel loci in the first genome-wide association study of youth-onset type 2 diabetes.     

Lipoma of the temporal region: a rare case series

Lipomas are common benign tumours that can occur in most parts of the body. Lipomas arising from the deep temporal fat pad, found between the two layers of the deep temporal fascia, are rare, however; there has been only one documented case report to our knowledge. We describe a second case arising from the temporal fat pad in a patient treated at our unit, having previously reported the first one, and discuss the relevant anatomy and management.