Intrafibrillar mineralization deficiency and osteogenesis imperfecta mouse bone fragility.

Osteogenesis imperfecta (OI), a brittle bone disease, is known to result in severe bone fragility. However, its ultrastructural origins are still poorly understood. In this study, we hypothesized that deficient intrafibrillar mineralization is a key contributor to the OI induced bone brittleness. To test this hypothesis, we explored the mechanical and ultrastructural changes in OI bone using the osteogenesis imperfecta murine (oim) model. Synchrotron X-ray scattering experiments indicated that oim bone had much less intrafibrillar mineralization than wild type bone, thus verifying that the loss of mineral crystals indeed primarily occurred in the intrafibrillar space of oim bone. It was also found that the mineral crystals were organized from preferentially in longitudinal axis in wild type bone to more randomly in oim bone. Moreover, it revealed that the deformation of mineral crystals was more coordinated with collagen fibrils in wild type than in oim bone, suggesting that the load transfer deteriorated between the two phases in oim bone. The micropillar test revealed that the compression work to fracture of oim bone (8.2 ± 0.9 MJ/m3) was significantly smaller (p < 0.05) than that of wild type bone (13.9 ± 2.7 MJ/m3), while the bone strength was not statistically different (p > 0.05) between the two genotype groups. In contrast, the uniaxial tensile test showed that the ultimate strength of wild type bone (50 ± 4.5 MPa) was significantly greater (p < 0.05) than that of oim bone (38 ± 5.3 MPa). Furthermore, the nanoscratch test showed that the toughness of oim bone was much less than that of wild type bone (6.6 ± 2.2 GJ/m3 vs. 12.6 ± 1.4 GJ/m3). Finally, in silico simulations using a finite element model of sub-lamellar bone confirmed the links between the reduced intrafibrillar mineralization and the observed changes in the mechanical behavior of OI bone. Taken together, these results provide important mechanistic insights into the underlying cause of poor mechanical quality of OI bone, thus pave the way toward future treatments of this brittle bone disease.

Abdominal cystic echinococcosis in Bangladesh: a hospital-based study.

INTRODUCTION: Cystic echinococcosis (CE) is reported from nearly all geographic areas of Bangladesh, but little information is available on its epidemiologic and clinical features. The aim of this study was to describe the clinical manifestations of hepatic and abdominal CE cases presenting to tertiary referral hospitals in Dhaka, Bangladesh. METHODOLOGY: A retrospective study was conducted via chart reviews of hepatic and abdominal CE patients under care at tertiary referral hospitals in Dhaka, Bangladesh, between 2002 and 2011. Age, sex, education level, occupation, urban versus rural residence, drinking water source, history of dog ownership, cyst type and location, and clinical manifestations were recorded for all patients. RESULTS: Of the 130 patients enrolled, 92 (70.8%) were female and 38 (29.2%) were male. The majority of patients were from rural (76.2%) rather than urban (23.8%) areas. All cases were from the northern part of the country, with no cases reported from the south or southeast. Most patients were between 21 and 40 years of age. A total of 119 patients (91.5%) had cysts only in the liver, with the remaining 8.5% having cysts in both the liver and lungs or in the abdominal cavity. Seventy-six (58.5%) of the hepatic cysts were stage CE1, indicating recent infection. CONCLUSIONS: Active transmission of Echinococcus granulosus appears to be occurring in Bangladesh, as indicated by the high number of CE1 hepatic cysts seen at tertiary care hospitals. Community ultrasound screening studies are warranted to better define the distribution of cases and risk factors for parasite transmission.