Biodegradation of BTEX at high salinity by an enrichment culture from hypersaline sediments of Rozel Point at Great Salt Lake.

AIMS: The primary goal of this research was to assess the biodegradation of benzene, toluene, ethylbenzene and xylenes in sediment from Great Salt Lake, near Rozel Point, UT. METHODS AND RESULTS: An enrichment culture that degraded benzene or toluene as the sole carbon source at high salinity was developed from a sediment sample obtained from Rozel Point. The enrichment degraded benzene or toluene within 1, 2 and 5 weeks in the presence of 14%, 23% and 29% NaCl respectively. PCR studies using degenerate primers revealed that degradation occurred primarily via catechol and the meta-cleavage pathway. Molecular analysis showed that the Gammaproteobacteria were the dominant members of the enrichment and that shifts in community composition occurred during benzene metabolism. CONCLUSIONS: This study demonstrated that micro-organisms at Rozel Point have the ability to degrade hydrocarbons over a broad range of salinities (1-5 mol l(-1) NaCl) and that the members of the Gammaproteobacteria class play an important role in the degradation process. SIGNIFICANCE AND IMPACT OF THE STUDY: These results are significant as little is known about the fate of petroleum seeps at Rozel Point. Also, the identity of microbes and the key enzymes involved in the degradation steps are important for understanding natural attenuation potential of hydrocarbons.

The chondrogenic repair response of undifferentiated mesenchymal cells in rat full-thickness articular cartilage defects.

OBJECTIVE: The aim of this study is to develop a rat model of full-thickness articular cartilage defects that is suitable for detailed molecular analyses of the regenerative repair of cartilage. MATERIALS AND METHODS: The V-shaped full-thickness defects (width: 0.7 mm; depth: 0.8 mm; and length: 4mm) were created in the femoral patellar groove of 6 weeks old male rats using a custom-built twin-blade device. Prior to starting the repair experiments, our device was examined for its accuracy and reliability in generating defects. Then, the time course of the repair response in these cartilage defects was examined using a semi-quantitative histological grading scale. The expression of chondrogenic differentiation markers in the reparative regions was examined with immunohistochemistry and in situ hybridization. RESULTS: Our device creates full-thickness articular cartilage defects uniformly. In these defects, undifferentiated mesenchymal cells filled the defect cavities (4 days) and initiated chondrogenic differentiation at the center of the defect (7 days). Cartilage formation was observed in the same region (2 weeks). Finally, hyaline-like articular cartilage and subchondral bone layers were reconstituted in their appropriate locations (4 weeks). CONCLUSIONS: We have successfully developed a rat model containing identically sized full-thickness defects of articular cartilage that can undergo chondrogenic repair in a reproducible fashion.

Healing of full-thickness defects of the articular cartilage in rabbits using fibroblast growth factor-2 and a fibrin sealant.

We have investigated in vitro the release kinetics and bioactivity of fibroblast growth factor-2 (FGF-2) released from a carrier of fibrin sealant. In order to evaluate the effects of the FGF-2 delivery mechanism on the repair of articular cartilage, full-thickness cylindrical defects, 5 mm in diameter and 4 mm in depth, which were too large to undergo spontaneous repair, were created in the femoral trochlea of rabbit knees. These defects were then filled with the sealant. Approximately 50% of the FGF-2 was released from the sealant within 24 hours while its original bioactivity was maintained. The implantation of the fibrin sealant incorporating FGF-2 successfully induced healing of the surface with hyaline cartilage and concomitant repair of the subchondral bone at eight weeks after the creation of the defect. Our findings suggest that this delivery method for FGF-2 may be useful for promoting regenerative repair of full-thickness defects of articular cartilage in humans.

The use of titanium surgical mesh-bone graft composite in the anterior thoracic or lumbar spine after complete or partial corpectomy.

Various conditions such as fracture, dislocation, tumor, or infection adversely affect the vertebral body and lead to instability. Restoration of a stable anterior column is essential for normal spinal biomechanics. Various biological and mechanical spacers have been used to reconstruct the anterior column after corpectomy. In this retrospective review, the authors evaluated clinical charts and radiographs of 13 patients receiving titanium surgical mesh (TSM)-bone graft composite to reconstruct the anterior spinal column in the thoracic or lumbar region. The objective of this review was to evaluate the stability and efficacy of the TSM-bone graft composite in the anterior spine after a complete or partial corpectomy. Sixteen patients with involvement of the thoracic or lumbar vertebral column after trauma, tumor, or infection underwent partial or complete corpectomy. In all patients the anterior defect was reconstructed using a TSM-bone graft composite. Three patients died within 12 months postoperatively due to primary malignant process. Thirteen of 16 patient charts and radiographs were evaluated for anterior fusion status, settling of the TSM-bone graft composite, and hardware failure. No pseudoarthroses were noted. Evidence of solid anterior fusion was noted in all patients. The average settling of the TSM-bone graft construct was 3 mm. All patients presenting with only pain and no neurological symptoms (n = 9) experienced early pain relief. For patients presenting with neurological symptoms (n = 4), the recovery was complete in three and partial in one. No patient was made neurologically worse, and there were no vascular injuries intra- or postoperatively. The study suggests that TSM-bone graft composite offers excellent biomechanical stability in the immediate postoperative period, permitting progressive maturation of the fusion mass.

Stress-protecting effects of semi-rigid titanium alloy plates on osteotomized rabbit tibiae.

We have examined the stress-protecting effects of titanium alloy (Ti-6A1-4V) plates of various thicknesses on osteotomized rabbit tibiae. We used three kinds of plates: One had a load-deflection rate close to that of intact rabbit tibiae (Group A), the other two had rates of one-fourth (Group B) and one-eighth (Group C) that of intact rabbit tibiae. No mechanical failure in the plates was observed, and bone healing occurred by eight weeks after operation in every group. Bone mass at 24 weeks after operation showed significantly less reduction in Groups B and C than in Group A. In biomechanical tests at 24 weeks, maximum energy stored to the maximum load in Group C had recovered significantly more than that of Group A. These findings suggested that it is possible to make a semi-rigid metal plate without using composite materials.

[Spontaneous regression of lumbar hernia of the nucleus pulposus. Follow-up study of 4 cases by repeated magnetic resonance imaging]. / Régression spontanée des hernies du nucleus pulposus au niveau lombaire. 4 cas suivis par des IRM répétées.

INTRODUCTION: As yet there have been no consistent magnetic resonance (MR) imaging studies on spontaneous regression of herniated lumbar nucleus pulposus (HNP). We present four patients in whom follow-up MRI images demonstrated spontaneous regression or complete disappearance of a herniated lumbar nucleus pulposus. One patient presented with a large extruded type, and the rest had the sequestrated type. All patients made evolved favorably with conservative therapy. RESULTS: Follow-up MRI images revealed a remarkable regression of the HNP in the extrusion case and complete disappearance in the sequestration cases. In the extrusion case, follow-up MRI images showed rapid shrinkage of the portion extruded into the epidural space. In the sequestration cases, MR images with Gadolinium DTPA (enhanced MR images) showed that the enhanced lesion around the HNP had reduced its size as the HNP diminished. Final MR images could not detect the HNP in any view of the spinal canal. CONCLUSION: We therefore concluded that the regression of HNP in MR images might have been due more to resorption than to dehydration.

Knee articular cartilage injury in leg lengthening. Histological studies in rabbits.

The effect of lengthening the tibia, by callotasis on the articular cartilage in the knee, was investigated histologically in 18 rabbits. The distraction rate was 1 mm per day. On the right tibia, the distraction frequency was in 2 steps (0.5mm/12 hours), while on the left it was in 120 steps (0.0083 mm/12 minutes). The 18 animals were divided into 3 subgroups based on length gain. Cartilage and subchondral bone samples were examined by light and fluorescent microscopy. The incidence of cartilage degeneration on the 2-step side was 2/5, 5/6, and 6/7 at 10, 20, and 30 percent length increases. On the 120-step side it was 0/5, 1/6, and 1/7 at the same length increases. The intensity of tetracycline fluorescence of the subchondral plate on the 2-step side was higher than that on the 120-step side, showing 1.7, 2.0, and 2.3-fold increases at 10, 20, and 30 percent length increases. Our study suggests that increasing the frequency of distraction in callotasis can help to prevent damage to articular cartilage in adjacent joints.

Cervical spinal epidural hematoma with spontaneous remission.

Spinal epidural hematoma (SEH) is comparatively rare. In most cases, urgent surgical decompression is necessary. Several reports have described spontaneous remission of SEH. The authors present a rare case of spontaneous resolution of cervical SEH.