Third-body wear testing of a highly cross-linked acetabular liner: the effect of large femoral head size in the presence of particulate poly(methyl-methacrylate) debris

The hip simulator wear performance of an electron beam cross-linked and subsequently melted ultrahigh molecular weight polyethylene against femoral heads of 28-, 38-, and 46-mm diameter in the presence of poly(methyl-methacrylate) particulate debris was contrasted with that of conventional polyethylene against a 46-mm diameter head. Over 5 million cycles of testing, the average wear rate of the conventional polyethylene liners was 29.3 +/- 3.0 mg per million cycles. All highly cross-linked components exhibited marked reduction in wear, with the highest wear measuring 0.74 +/- 0.85 mg per million cycles. This study, using a clinically relevant third-body material, showed the electron beam cross-linked material to be far more resistant to this third-body wear than conventional ultrahigh molecular weight polyethylene, even when very large diameter femoral heads were used.     

Morphology of tumours induced in hamsters by CELO virus, tumour tissue, and tumour cells grown in culture

Tumours in hamsters, induced by the chicken-embryo-lethal-orphan (CELO) virus, by tumour tissue transplants, or by tumour cells grown in culture, were well circumscribed solid tumours and covered by a thin capsule-like structure. All were fibrosarcomata. However, tumours produced by the 3 inocula exhibited the following histological differences. Neoplasms induced by CELO virus were generally less differentiated and were composed of cells with polygonal or oval nuclei and indistinct cytoplasmic boundaries. Numerous multinucleated bizarre giant cells were found. Those produced by tumour tissue transplants were more differentiated and were composed of spindle shaped cells with abundant collagen fibre formation. Neoplasms induced by tumour cells grown in culture were generally undifferentiated with many mitotic figures and contained numerous giant cells.     

Extensive acquired cholesteatoma in children: when the penny drops

OBJECTIVES: To determine the factors associated with the diagnosis of acquired cholesteatoma (AC) in children, we performed a retrospective chart review at a tertiary care center. METHODS: We reviewed children with a diagnosis of AC that extended beyond the mesotympanum in the presence of a nonintact tympanic membrane who underwent surgical treatment over a 14-year period. RESULTS: There were 116 children (78 male, 38 female) between 3 and 18 years of age (mean, 9.5 years). Their average period of management in a specialist otolaryngology clinic before the diagnosis of cholesteatoma was made was 3.2 years, and 68% of the children had previously undergone insertion of tympanostomy tubes. Symptoms and signs included chronic otorrhea (59%), recurrent acute otitis media (58%), and conductive hearing loss (51%). The diagnosis of AC was eventually made after office otoscopy (26%), temporal bone computed tomography (24%), or examination under anesthesia (17%). In 33% of children, the diagnosis was made only after surgical exploration of the middle ear and mastoid. CONCLUSIONS: Our data underscore the importance of maintaining a high index of suspicion for AC in managing children with long-standing otologic symptoms, and considering otomicroscopy, computed tomographic scanning, or tympanomastoid exploration if medical treatment fails.     

A review of 1H MR spectroscopy findings in Alzheimer's disease

Hydrogen-1 MR spectroscopy (MRS) studies demonstrate metabolic differences between patients who have Alzheimer's disease (AD) and cognitive normal age-matched controls. Clinical MRS also shows regional variations in metabolites between patients who have AD and those who have other dementias. Single-voxel and volumetric standard MRS techniques and automated data processing software are available for clinical MR scanners. Improvements in specificity and sensitivity of AD diagnosis, using MRS techniques as an adjunct to clinical imaging, are under evaluation. Multiparametric data analyses show, however, that metabolite changes correlate with in-vitro, postmortem, and metabolic changes and to changes in or predictions of cognitive scores.