Peripheral corneal ulcers associated with use of African traditional eye medicines.

The most common cause of monocular blindness in Africa is corneal opacification. Traditional eye medicines (TEM) are widely used in Africa and their use has been associated with corneal ulceration, however, no controlled studies of the effects of TEM on the cornea have been published. We conducted a case-control study of 39 patients with corneal ulcers matched to controls with severe conjunctivitis. Microbiological investigations were conducted on 20 cases. There was a significant association between corneal ulceration and TEM use and, in particular, peripheral corneal ulcerations were significantly associated with TEM use.     

Quantification of bone healing. Comparison of QCT, SPA, MRI, and DEXA in dog osteotomies

Four noninvasive imaging modalities were used to quantitatively evaluate and compare tibial osteotomy healing in dogs. Quantitative computed tomography (QCT), magnetic resonance imaging (MRI), single-photon absorptiometry (SPA), and dual-energy x-ray absorptiometry (DEXA) were the four techniques examined. Bilateral tibial osteotomies were performed in 32 dogs divided into four groups. The osteotomies were stabilized with a 2-mm gap using unilateral external skeletal fixation. Dogs were anesthetized, imaged with the four noninvasive techniques, and killed at 2-12 weeks. Invasive techniques were used to determine: 1) the torsional properties of the bone; and 2) the local stiffness properties and calcium content within the bone. The techniques which had the strongest associations with the torsional properties of the osteotomies were QCT, SPA and DEXA. Generally, QCT and SPA had marginally stronger correlations than DEXA; but, overall, there were no differences between the techniques. MRI had the poorest associations with the torsional properties of the osteotomies. Generally, QCT had the strongest correlations with local material properties, such as indentation stiffness and calcium content. SPA had the second strongest correlations with calcium content and had the third strongest correlations with indentation stiffness behind DEXA. DEXA had the third strongest correlations for calcium content. With the exception of some of the correlations with indentation stiffness, MRI had the poorest associations with the local parameters studied.     

Low-artifact intravascular devices: MR imaging evaluation

Flow-phantom magnetic resonance (MR) imaging, with use of both spin-echo (SE) and gradient-echo (GRE) techniques at 1.5 T, was performed on the percutaneous Greenfield (beta-III titanium alloy [TMA wire]), Amplatz (MP32-N alloy), and Simon nitinol filters and TMA wire facsimiles of the bird's nest, Gunther, new retrievable, and Amplatz vena caval filters. SE imaging allowed detection of thrombi as small as 5 X 5 mm trapped within the percutaneous Greenfield, Simon nitinol, and TMA-wire facsimile filters; with the MP32-N Amplatz filter, a larger volume of thrombus (10 X 20-mm clots) was necessary for clot detection. GRE imaging allowed detection of intraluminal tilting of the percutaneous Greenfield and facsimile Amplatz (TMA-wire) filters. GRE imaging was useful for demonstrating postfilter turbulence due to clots, which was greatest for the Amplatz filter. Imaging of facsimile vascular devices made of tantalum or TMA wire did not cause the severe "black-hole" MR artifacts typical of the stainless-steel devices. SE and GRE imaging were very useful for determining caval patency in two patients with previously placed Mobin-Uddin filters. Noninvasive MR evaluation of blood vessels in the presence of a variety of low-artifact intravascular devices appears feasible.     

Chondroconductive potential of tantalum trabecular metal

Mesenchymal stem cells or chondrocytes have been implanted into joints in biodegradable matrices in order to improve the quality of healing cartilage defects; however, insufficient biomechanical strength of the construct at implantation is a limiting factor for clinical application. Logically, a construct with better biomechanical characteristics would provide better results. Tantalum trabecular metal (TTM) is osteoconductive and mechanically similar to subchondral bone. The objective of this pilot study was to determine if TTM is also chondroconductive. Small sections of TTM were cultured with emu and canine chondrocytes in static and dynamic culture environments. The sections cultured in dynamic bioreactors were diffusely covered with a cartilaginous matrix. Sections cultured in static conditions had no growth. Histologic evaluation from emu and canine dynamic cultures showed tissue that was heavily populated with mesenchymal cells that resembled chondrocytes, and glycosaminoglycan staining that was distributed throughout the matrix. Type II collagen content in the canine dynamic culture was 84% by SDS-PAGE. Tantalum trabecular metal is chondroconductive in vitro in a dynamic environment when cultured with adult canine or emu chondrocytes. This technology could be expanded to determine if cartilaginous-metallic constructs may be used for joint resurfacing of osteoarthritic joints.     

Osteopetrosis: MR characteristics at 1.5 T

Four patients with proved osteopetrosis (three with the infantile malignant form and one with the benign form) were examined with magnetic resonance imaging at 1.5 T. All patients were studied in the coronal and sagittal planes using both short and long repetition time/echo time sequences. The infantile malignant form was characterized by a complete lack of signal from the marrow alternating with a signal intensity equivalent to that of the intervertebral disks, resulting in a "stepladder" appearance. In the benign form or after successful marrow transplantation in the infantile malignant form, intermediate or high signal intensity in the vertebrae was noted, suggesting the presence of some marrow elements.