Clinical and radiographic analysis of osteochondromas and growth disturbance in hereditary multiple exostoses

Hereditary multiple exostoses (HME) is traditionally described as a skeletal dysplasia. However, the discovery that the EXT family of tumour suppressor genes are responsible for HME suggests that it is more appropriate to classify HME as a familial neoplastic trait. In a clinical and radiographic analysis of paired bone length and exostoses number and dimensions in a HME cohort, the local presence of osteochondromas was consistently associated with growth disturbance. In particular, an inverse correlation between osteochondroma size and relative bone length (p<0.01) was found. These data suggest that the growth retardation in HME may result from the local effects of enlarging osteochondromas rather than a skeletal dysplasia effect. This study provides the first clinical rationale for ablation of rapidly enlarging exostoses to reduce growth disturbance.     

Functional MT + lesion impairs contralateral motion processing

Human motion processing region MT + is retinotopically organized with perception of and attention to motion in the right visual field preferentially associated with left MT + activity and vice versa. However, the degree to which MT + is crucial for motion processing is uncertain. We report an epilepsy patient with visual symptoms early in his seizure evolution and a left temporal-occipital seizure onset electrographically in whom we hypothesized a functional left MT + lesion. The patient was impaired in his right but not left visual field on a hemifield motion attention task and demonstrated worse performance on a hemifield picture identification task when pictures implying motion were presented in the right as opposed to the left visual field. Functional MRI (fMRI) during a full-field motion detection task activated right MT + but failed to activate left MT + despite activating both left and right MT + in each of 10 controls. Furthermore, fMRI during a hemifield motion attention task also showed a lack of left MT + attention effects in the patient. Together these results suggest that MT + is necessary for normal motion processing.     

Inter-species extrapolation of skin heating resulting from millimeter wave irradiation: modeling and experimental results

This study reports measurements of the skin surface temperature elevations during localized irradiation (94 GHz) of three species: rat (irradiated on lower abdomen), rhesus monkey (posterior forelimb), and human (posterior forearm). Two exposure conditions were examined: prolonged, low power density microwaves (LPM) and short-term, high power density microwaves (HPM). Temperature histories were compared with calculations from a bio-heat transfer model. The mean peak surface temperature increase was approximately 7.0 degrees C for the short-term HPM exposures for all three species/locations, and 8.5 degrees C (monkey, human) to 10.5 degrees C (rat) for the longer-duration LPM exposures. The HPM temperature histories are in close agreement with a one-dimensional conduction heat transfer model with negligible blood flow. The LPM temperature histories were compared with calculations from the bio-heat model, evaluated for various (constant) blood flow rates. Results suggest a variable blood flow model, reflecting a dynamic thermoregulatory response, may be more suited to describing skin surface temperature response under long-duration MMW irradiation.     

A Comparison of Voxel-Based Morphometry and Volumetry Methods in the Context of the Neural Basis of Aggression

The assumption that voxel-based morphometry (VBM) offers an automated substitution for manually-traced volumetry was subjected to empirical evaluation. Data available from a previous volumetry study (Gansler et al. Psychiatry Research: Neuroimaging 171:145–154, 2009) provided the basis for the current study, which assessed for convergence between the methods. Optimized modulated VBM was used to preprocess images (N = 40). Gray matter volume and self-reported aggression associations were tested. Results indicate convergence, as both methods revealed significant negative associations of the left orbitofrontal cortex (OFC) and aggression. VBM detected an additional positive left OFC result not revealed with volumetry, suggesting that VBM may allow greater within-region localization than volumetry. However, the methods differentially deal with error rates and power demands and as such are better conceptualized as complementary than interchangeable.     

Primary Human Osteoblast Proliferation and Prostaglandin E2 Release in Response to Mechanical Strain In Vitro

The application of mechanical loads to bone cells in vitro has been found to generate variable responses, which may in part be due to the source of the cell used and the characteristics of the strain applied. The aim of this study was to establish a system for applying well-defined physiological levels of mechanical strain to a well-defined population of human osteoblast-like cells. Human bone-derived cells obtained from the greater trochanter of the femur during total hip arthroplasty for osteoarthritis were cultured in the presence of 10 nmol/L dexamethasone and 100 μmol/L l-ascorbate-2-phosphate. Replicates of cells from each patient were loaded on separate occasions using controlled cyclical strains of 4000 microstrain (μ) or less. Strain gauges recorded reliable, reproducible strains between 1000 and 6000 μ. To establish reproducibility, sequential explant cultures derived from two patients were studied. A consistent increase (p < 0.05) in proliferation between replicates and explants derived from one patient subjected to 1600 μ on separate occasions was observed. Cells derived from sequential explants of the second patient showed no consistent increase in proliferation between replicates and explants. Three of six patients showed a significant increase (p < 0.05) in PGE₂ production after 5 h in response to stretch (4000 μ) in all replicates on separate occasions, whereas, in the other three populations of cells, no increase in PGE₂ was measured in any of the replicates. These results show that the application of highly controlled strains causes a significant effect on human bone cells, but only in a proportion of subjects. The response is consistent between sequential explants derived from the same patient. The implications of this study are that human osteoblast-like cells do respond to physiological strain in vitro, although some cells are more strain sensitive than others.     

A double-blind crossover trial of Oral Balance gel and Biotene toothpaste versus placebo in patients with xerostomia following radiation therapy.

Following therapeutic irradiation of the head and neck, patients with profound xerostomia have complaints associated with oral dryness, effects upon use of oral prosthesis, speech, and taste. In addition, xerostomia may lead to risk of oral infections and rampant demineralization of teeth. The use of topical Oral Balance gel and Biotene toothpaste (Laclede Professional Products, Gardena, CA) versus carboxymethylcellulose gel and commercial toothpaste applications was assessed in a 2-week double-blind, crossover design. The palliative effects of Oral Balance gel and Biotene toothpaste were superior to the effects of a placebo. No effect on oral colonization by Candida species and cariogenic oral microflora was seen with use of the topical agents.