Emerging investigator series: Coprecipitation with glucuronic acid limits reductive dissolution and transformation of ferrihydrite in an anoxic soil.

Ferrihydrite, a poorly crystalline Fe(III)-oxyhydroxide, is abundant in soils and is often found associated with organic matter. Model studies consistently show that in the presence of aqueous Fe(II), organic carbon (OC)-associated ferrihydrite undergoes less transformation than OC-free ferrihydrite. Yet, these findings contrast microbial reductive dissolution studies in which the OC promotes the reductive dissolution of Fe(III) in ferrihydrite and leads to the release of associated OC.

Coprecipitation with Ferrihydrite Inhibits Mineralization of Glucuronic Acid in an Anoxic Soil.

It is known that the association of soil organic matter (SOM) with iron minerals limits carbon mobilization and degradation in aerobic soils and sediments. However, the efficacy of iron mineral protection mechanisms under reducing soil conditions, where Fe(III)-bearing minerals may be used as terminal electron acceptors, is poorly understood. Here, we quantified the extent to which iron mineral protection inhibits mineralization of organic carbon in reduced soils by adding dissolved C-glucuronic acid, a Fe-ferrihydrite-C-glucuronic acid coprecipitate, or pure Fe-ferrihydrite to anoxic soil slurries.

Mineral characterization and composition of Fe-rich flocs from wetlands of Iceland: Implications for Fe, C and trace element export.

In freshwater wetlands, redox interfaces characterized by circumneutral pH, steep gradients in O, and a continual supply of Fe(II) form ecological niches favorable to microaerophilic iron(II) oxidizing bacteria (FeOB) and the formation of flocs; associations of (a)biotic mineral phases, microorganisms, and (microbially-derived) organic matter. On the volcanic island of Iceland, wetlands are replenished with Fe-rich surface-, ground- and springwater. Combined with extensive drainage of lowland wetlands, which forms artificial redox gradients, accumulations of bright orange (a)biotically-derived Fe-rich flocs are common features of Icelandic wetlands.

Pedicle screw anchorage of carbon fiber-reinforced PEEK screws under cyclic loading.

Purpose: Pedicle screw loosening is a common and significant complication after posterior spinal instrumentation, particularly in osteoporosis. Radiolucent carbon fiber-reinforced polyetheretherketone (CF/PEEK) pedicle screws have been developed recently to overcome drawbacks of conventional metallic screws, such as metal-induced imaging artifacts and interference with postoperative radiotherapy. Beyond radiolucency, CF/PEEK may also be advantageous over standard titanium in terms of pedicle screw loosening due to its unique material properties.

Diabulimia and the role of school health personnel.

Background: Diabulimia, the omission or reduction of insulin use by persons with type 1 diabetes, is a harmful method of weight control. The purpose of this article is to present school health personnel with the information they may need to become more aware of the possibility of diabulimia in their students-especially females-with type 1 diabetes.

Methods: A review of the somewhat limited medical and diabetes-related organizations' literature on diabulimia was conducted to establish the role that school health personnel could play in raising awareness of students with this condition as well as education for diabulimia prevention.

Influence of a dynamic stabilisation system on load bearing of a bridged disc: an in vitro study of intradiscal pressure.

In recent years, non-fusion implants to stabilise the lumbar spine have become more and more popular. However, little is known on the load bearing of such dynamic stabilisation systems. In order to investigate the load bearing of discs bridged with rigid and dynamic stabilisation systems, six lumbar cadaver spines were mounted in a spine tester and loaded with pure moments in the three main motion planes.

Three-dimensional stabilization provided by the external spinal fixator compared to two internal fixation devices: a biomechanical in vitro flexibility study.

We performed an in vitro study to investigate the stabilization (i.e. motion reduction) provided by the external spinal fixator (ESF), and to compare the three configurations of the ESF with two internal fixation techniques.

Dynamic stabilization of the lumbar spine and its effects on adjacent segments: an in vitro experiment.

In recent years, nonfusion stabilization of the lumbar spine has gained more and more popularity. These nonfusion systems intend to maintain or restore the intersegmental motions to magnitudes of the intact spine and have no negative effects on the segments adjacent to the stabilized one. This study investigated the DYNESYS, a dynamic nonfusion system, which is designed to stabilize the bridged segments while maintaining the disc and the facet joints.

A memory coiling spiral as nucleus pulposus prosthesis: concept, specifications, bench testing, and first clinical results.

The intradiscal cavity left after a discectomy can be filled by a new nucleus prosthesis made of polycarbonate urethane in the form of a "memory coiling spiral." Biomechanical tests have demonstrated that this device compensates for the loss of disc height, decreases the compression of the facet joints, and restores the kinematics of the spinal segment, without deformation of the vertebral endplates or migration. The device is currently under clinical investigation.

Is there a connection between the clinical response after an external fixation test or a subsequent lumbar fusion and the pre-test intervertebral kinematics?

Study Design: Evaluation of a possible correlation of clinical symptoms of chronic low back pain (LBP) patients before and after application of external spinal fixation (ESF) with three-dimensional motion patterns.

Objective: To determine whether the intervertebral kinematics in chronic LBP patients correlate with pain relief after stabilization of the suspected painful segments.

Summary Of Background Data: Chronic LBP is a complex clinical entity with mechanical, biochemical, and psychosocial components.

A spiral implant as nucleus prosthesis in the lumbar spine.

Microdiscectomy represents the gold standard in disc surgery on the lumbar spine. The remaining defect in the intervertebral disc space can be filled with a newly developed nucleus prosthesis presented in this paper. This prosthesis consists of polycarbonate urethane (Sulene PCU), and takes the form of a memory coiling spiral.

Three-dimensional motion patterns during active bending in patients with chronic low back pain.

Study Design: The three-dimensional motion patterns of chronic low back pain (LBP) patients were studied during active motions.

Objective: To evaluate whether the motion patterns of coupling and asymmetry in chronic LBP patients differ from those in the normal population according to previous literature.

Summary Of Background Data: There exists little data that correlates vertebral motion with LBP symptoms despite extensive research.

Does anterolateral cage insertion enhance immediate stabilization of the functional spinal unit? A biomechanical investigation.

Study Design: The three-dimensional flexibility of six human lumbar functional spinal units was measured after the anterolateral insertion of an interbody cage.

Objectives: To determine whether an interbody cage inserted from an anterolateral direction stabilizes the spine with respect to the intact state and to compare the finding with that from the same cage inserted from an anterior direction.

Summary Of Background Data: Several biomechanical studies have shown that interbody cages do not stabilize the spine in extension.

A comparative biomechanical investigation of anterior lumbar interbody cages: central and bilateral approaches.

Background: Some biomechanical studies have been performed to evaluate the stabilization provided by interbody cages, but there are virtually no comparative data for the different designs. Furthermore, most investigators have used animal models, which may have led to different results due to morphological variation in the end plates and articular facets. The objectives of the current study were to evaluate whether two different anterior cage designs (BAK and SynCage) performed differently with respect to immediate stabilization of the spine, whether the cages stabilized the spine significantly compared with its intact condition, and whether the addition of supplementary translaminar screw fixation further stabilized the spine.

Interface shear strength of titanium implants with a sandblasted and acid-etched surface: a biomechanical study in the maxilla of miniature pigs.

The purpose of the present study was to evaluate the interface shear strength of unloaded titanium implants with a sandblasted and acid-etched (SLA) surface in the maxilla of miniature pigs. The two best documented surfaces in implant dentistry, the machined and the titanium plasma-sprayed (TPS) surfaces served as controls. After 4, 8, and 12 weeks of healing, removal torque testing was performed to evaluate the interface shear strength of each implant type.

Removal torque values of titanium implants in the maxilla of miniature pigs.

The purpose of this study was to compare side-by-side two different titanium screw-type implants in the maxillae of miniature pigs. The test implants had a machined and acid-etched surface (Osseotite) whereas the control implants were sandblasted and acid-etched (SLA). After 4, 8, and 12 weeks of healing, removal torque testing was performed to evaluate the shear strength of the bone-implant interface for both implant types.

Two monoclonal antibodies that discriminate between allelic variants of human low density lipoprotein.

Human low density lipoprotein shows a genetic polymorphism, the so-called Ag-system. it consists of 5 pairs of allelic epitopes, x/y, al/d, c/g, t/z, and h/i, which are localized on apolipoprotein B. We have generated a large number of monoclonal antibodies against low density lipoprotein.