Glutaraldehyde-cross-linked meniscal allografts: clinical, gross, and histological results.

Osteoarthritic changes in the knee are often a late result of total meniscectomy. In cases of total resection, availability of a prosthetic meniscus might limit development of these changes. The objective of this research was to evaluate a glutaraldehyde-cross-linked medial meniscus as a morphologically and biologically compatible prosthesis in a canine model. Medial and lateral menisci were harvested from donor dogs, frozen in saline, and cross-linked with glutaraldehyde. Five host animals were selected and matched with donors. Glutaraldehyde-cross-linked medial menisci were implanted bilaterally in the stifle joints and one glutaraldehyde cross-linked lateral meniscus was implanted subcutaneously. Clinical results showed asymptomatic limb and joint usage during the 12 postoperative weeks. Gross and histological evaluations indicated acceptable biocompatibility. The subcutaneous implants were encapsulated with a thin fibrous tissue capsule that was only mildly inflamed. Within the joints, the anterior attachment and periphery were maintained in position by their sutures; however, there was dehiscence of the posterior suture in all cases. The articulating surfaces of the implants were intact. There was an initial loss in the quantity of proteoglycans following glutaraldehyde treatment, with significant recovery after implantation into the joints. There were significant degenerative changes (loss of proteoglycans and fibrillation) in the articular cartilage on the femoral condyle and tibial plateau most likely a result of the posterior attachment failure. It was concluded that glutaraldehyde-cross-linked meniscal allografts showed an acceptable degree of histocompatibility. However, failure of the posterior attachment interfered with testing the efficacy of the prosthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Ajuga turkestanica increases Notch and Wnt signaling in aged skeletal muscle.

BACKGROUND: The declining myogenic potential of aged skeletal muscle is multifactorial. Insufficient satellite cell activity is one factor in this process. Notch and Wnt signaling are involved in various biological processes including orchestrating satellite cell activity within skeletal muscle. These pathways become dysfunctional during the aging process and may contribute to the poor skeletal muscle competency. Phytoecdysteroids are natural adaptogenic compounds with demonstrated benefit on skeletal muscle. AIM: To determine the extent to which a phytoecdysteroid enriched extract from Ajuga turkestanica (ATE) affects Notch and Wnt signaling in aged skeletal muscle. MATERIALS AND METHODS: Male C57BL/6 mice (20 months) were randomly assigned to Control (CT) or ATE treatment groups. Chow was supplemented with either vehicle (CT) or ATE (50 mg/kg/day) for 28 days. Following supplementation, the triceps brachii muscles were harvested and immunohistochemical analyses performed. Components of Notch or Wnt signaling were co-labelled with Pax7, a quiescent satellite cell marker. RESULTS: ATE supplementation significantly increased the percent of active Notch/Pax7+ nuclei (p = 0.005), Hes1/Pax7+ nuclei (p = 0.038), active B-catenin/Pax7+ nuclei (p = 0.011), and Lef1/Pax7+ nuclei (p = 0.022), compared to CT. ATE supplementation did not change the resting satellite cell number. CONCLUSIONS: ATE supplementation in aged mice increases Notch and Wnt signaling in triceps brachii muscle. If Notch and Wnt benefit skeletal muscle, then phytoecdysteroids may provide a protective effect and maintain the integrity of aged skeletal muscle.

Hydrogenic spin quantum computing in silicon: a digital approach.

We suggest an architecture for quantum computing with spin-pair encoded qubits in silicon. Electron-nuclear spin-pairs are controlled by a dc magnetic field and electrode-switched on and off hyperfine interaction. This digital processing is insensitive to tuning errors and easy to model. Electron shuttling between donors enables multiqubit logic. These hydrogenic spin qubits are transferable to nuclear spin-pairs, which have long coherence times, and electron spin-pairs, which are ideally suited for measurement and initialization. The architecture is scalable to a highly parallel operation.