BackgroundThe influence of stem cells and lentiviral expression of basic fibroblastic growth factor (bFGF) on tendon healing and remodelling was investigated in an in-vivo long-term (12 weeks) rat Achilles tendon defect model.MethodsIn sixty male Lewis rats, complete tendon defects (2.4 mm) were created and either left untreated (PBS) or treated by injection of stem cells lentivirally expressing the enhanced green fluorescence marker gene eGFP (MSC-LV-eGFP) or basic fibroblast growth factor bFGF (MSC-LV-bFGF). Tendons were harvested after 12 weeks and underwent biomechanical and (immuno)-histological analysis.ResultsAfter 12 weeks the mean ultimate load to failure ratio (treated side to contralateral side) in biomechanical testing reached 97 % in the bFGF-group, 103 % in the eGFP-group and 112 % in the PBS-group. Also in the stiffness testing both MSC groups did not reach the results of the PBS group.Histologically, the MSC groups did not show better results than the control group. There were clusters of ossifications found in all groups. In immunohistology, only the staining collagen-type-I was strongly increased in both MSC groups in comparison to PBS control group. However, there were no significant differences in the (immuno)-histological results between both stem cell groups.ConclusionThe biomechanical and (immuno)-histological results did not show positive effects of the MSC groups on tendon remodelling in a long-term follow-up. Interestingly, in later stages stem cells had hardly any effects on biomechanical results. This study inspires a critical and reflected use of stem cells in tendon healing.

Different joint-preserving techniques have been described for the treatment of traumatic osteochondral lesions of the femoral head especially in young active patients. Mosaicplasty with autologous transplantation of osteochondral cylinders is an established surgical technique in the knee. Little evidence, however, exists for the treatment of osteochondral lesions in the hip using this technique. Here, we report on the result of treatment of a traumatic 5 cm(2) osteochondral lesion of the femoral head in a young patient treated with mosaicplasty. Grafts were taken from the ipsilateral knee. After 2 years, the outcome was satisfactory with partial return to previous activity level.

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We describe first beam collisions at the PEP-II B Factory, a collaboration of SLAC, LBNL, and LLNL. The beams are brought close to each other in the transverse (x,y) and longitudinal (timing) directions through the use of two shared beam position monitors located 0.72 m from either side of the interaction point (IP). Transverse beam-beam deflection scans and the use of a zero-angle luminosity detector allow us to center the collisions. Beam collisions were also seen by exciting one beam at its tune frequency and observing a response in the other beam at the same frequency. Shifts in betatron tunes have also been measured. To date, the peak measured luminosity attained is cm s with 786 bunches in each beam and with beam currents of 354 mA for the high-energy beam (HEB) and 680 mA for the low-energy beam (LEB). PEP-II PEP-II [1], an asymmetric-energy two-storage-ring accelerator, is designed to allow the study of the decay channels of the Upsilon (4S) resonance from a boosted centerof-mass system. The boost permits the separation in time of the decay of the matter and anti-matter B mesons the 4S produces thereby allowing one to look for asymmetries in the decay-time distributions of these mesons and hence a violation of CP conservation.The high-energy ring (HER) was completed first and a beam was stored in the ring in June of 1997. The lowenergy ring (LER) and the final interaction region beam pipes and magnets were finished and installed in July of 1998 with beam stored in the LER shortly thereafter. Table 1 lists some of the PEP-II design parameters.The PEP-II interaction region, shown in figure 1, employs two strong horizontal bending magnets (B1) located 21 cm from the IP to bring the beams into a head-on collision. On either side of the IP, the beams also pass through a shared quadrupole (QD1) which is centered on the HEB. This design places the LEB off-axis in this shared defocusing quad which further horizontally separates the two beams prior to the beams entering separate vacuum chambers. The next three magnets on either side of the IP are septum quadrupole magnets where one of the beams travels through a field-free region while the other is focused either horizontally or vertically. The first of these magnets (QF2) is a focusing magnet for the LEB and completes the final focus doublet for the LEB. The next two magnets (QD4 and QF5) are the final focus doublet for the HEB with the shared QD1 magnet supplying additional vertical focusing [2].