Sensory innervation of the cat knee articular capsule and cruciate ligament visualised using anterogradely transported wheat germ agglutinin–horseradish peroxidase

Wheat germ agglutinin–horseradish peroxidase conjugate (WGA–HRP) was injected into the dorsal root ganglia (L5–S1) of the cat and used as an anterograde tracer substance for intra-axonal labelling of peripheral nerve endings in joint capsule and cranial (anterior) cruciate ligament (CCL). We believed that the high specificity of WGA–HRP for neural tissue along with the high visibility of its reaction product could help resolve controversies concerning the sensory innervation of the cruciate ligaments. Substantial amounts of WGA–HRP were transported in tibial nerve axons to the level of the knee. However, using standard HRP histochemistry we found that the capsular tissue and ligament synovia disintegrated during the incubation reaction. This problem was avoided by air drying the tissue slices on glass slides prior to reaction. Abundant labelling occurred in the posterior capsule with dense filling of axons and terminal endings. Sensory endings displayed features consistent with Ruffini endings and pacinian corpuscles. Sensory endings were located throughout the CCL in its sagittal plane, in the subsynovial layers and between collagen fascicles. In each CCL we observed 5–17 ovoid and elongated endings with dense terminal arborisations. These endings were between 100 and 150 μm long, were encapsulated, and gave rise to 1 or 2 axons. Large (up to 1.5 mm in maximum extent) elongated regions of dense, inhomogeneous labelling were found in the body of several CCLs. These resembled Golgi tendon-like endings, with the exception of their large size. We conclude that anterograde transport of HRP to the knee is a useful technique for labelling mechanoreceptors and axons in knee tissue. However, recently developed immunohistochemical analysis of peripheral tissue using protein gene product 9.5 appears to be the method of choice and should be employed for further study of human and animal cruciate ligament innervation

Radiolytic and Thermal Processes Relevant to Dry Storage of Spent Nuclear Fuels

The scientific and engineering demands of the Department of Energy (DOE) Environmental Restoration and Waste Management tasks are enormous. For example, several thousand metric tons of metallic uranium spent nuclear fuel (SNF) remain in water storage awaiting disposition. Of this inventory, 2300 metric tons are N-Reactor fuel that have been stored for up to 24 years in the Hanford, Washington KBasins. No significant precautions were taken to prevent the fuel from corroding since the fuel rods were intended to be reprocessed. Termination of reprocessing has left these fuels stranded in prolonged water storage and an appreciable quantity of the fuel has corroded. In addition, other defense fuels including the aluminum-clad fuels at the Savannah River Site and Idaho National Engineering Laboratory have corroded during interim storage in water. In 1994, the DOE began to implement a strategy for moving water-stored Hanford fuels into dry interim storage and a Record of Decision 1 ( ROD) documenting this action was put forth by the Department of Energy on March 4, 1996. Several documents 1-4 including this ROD and the final environmental impact statement (FEIS)1, evaluated and documented concerns regarding the potential for releases of radionuclides to the environment. The DOE plans to remove metallic uranium SNF from water storage and seal it in overpack canisters for ''dry'' interim storage, for up to 75 years. Much of the SNF that will be stored will have been severely corroded during water storage. Chemically bound water not removed during proposed drying operations may lead to long-term corrosion and generation of combustible H2 and O2 gas-mixture via radiolysis. No thoroughly tested model is currently available to predict fuel behavior during ''dry'' storage. The PNNL collaborating with the Rutgers University studied the thermo-chemical and radiolytic reactions of actual and prototype SNF materials. The purpose of this project is to deliver pertinent information which can be used to make decisions concerning the safety and treatment issues associated with dry storage of spent nuclear fuel materials. In particular, we set out to establish an understanding of: (1) water interactions with failed-fuel rods and metal-oxide materials; (2) the role of thermal processes and radiolysis (solid-state and interfacial) in the generation of potentially explosive mixtures of gaseous H2 and O2, and (3) the potential role of radiation assisted corrosion during fuel rod storage. The project meets several major DOE/EMSP science needs for the Spent Nuclear Fuel Focus Area: (1) Stabilization of spent nuclear fuel, including mechanism of pyrophoricity and combustion parameters for various fuel types; (2) Characterization of spent nuclear fuel; (3) Development of methods to remove moisture without damage to fuel elements; and (4) Characterization of corrosion, degradation, and radionuclide release mechanisms, kinetics, and rates for fuel matrices

Far Cortical Locking Can Reduce Stiffness of Locked Plating Constructs While Retaining Construct Strength

Background: Several strategies to reduce construct stiffness have been proposed to promote secondary bone healing following fracture fixation with locked bridge plating constructs. However, stiffness reduction is typically gained at the cost of construct strength. In the present study, we tested whether a novel strategy for stiffness reduction, termed far cortical locking, can significantly reduce the stiffness of a locked plating construct while retaining its strength

Dynamic stabilization with active locking plates delivers faster, stronger, and more symmetric fracture-healing

BACKGROUND: Axial dynamization of fractures can promote healing, and overly stiff fixation can suppress healing. A novel technology, termed active plating, provides controlled axial dynamization by the elastic suspension of locking holes within the plate. This prospective, controlled animal study evaluated the effect of active plates on fracture-healing in an established ovine osteotomy model. We hypothesized that symmetric axial dynamization with active plates stimulates circumferential callus and delivers faster and stronger healing relative to standard locking plates. METHODS: Twelve sheep were randomly assigned to receive a standard locking plate or an active locking plate for stabilization of a 3-mm tibial osteotomy gap. The only difference between plates was that locking holes of active plates were elastically suspended, allowing up to 1.5 mm of axial motion at the fracture. Fracture-healing was analyzed weekly on radiographs. After sacrifice at nine weeks postoperatively, callus volume and distribution were assessed by computed tomography. Finally, to determine their strength, healed tibiae and contralateral tibiae were tested in torsion until failure. RESULTS: At each follow-up, the active locking plate group had more callus (p < 0.001) than the standard locking plate group. At postoperative week 6, all active locking plate group specimens had bridging callus at the three visible cortices. In standard locking plate group specimens, only 50% of these cortices had bridged. Computed tomography demonstrated that all active locking plate group specimens and one of the six standard locking plate group specimens had developed circumferential callus. Torsion tests after plate removal demonstrated that active locking plate group specimens recovered 81% of their native strength and were 399% stronger than standard locking plate group specimens (p < 0.001), which had recovered only 17% of their native strength. All active locking plate group specimens failed by spiral fracture outside the callus zone, but standard locking plate group specimens fractured through the osteotomy gap. CONCLUSIONS: Symmetric axial dynamization with active locking plates stimulates circumferential callus and yields faster and stronger healing than standard locking plates. CLINICAL RELEVANCE: The stimulatory effect of controlled motion on fracture-healing by active locking plates has the potential to reduce healing complications and to shorten the time to return to function