Problem Thoracic disc disease with radicular pain and myelopathic symptoms can have serious neurological sequelae. The authors present a relevant treatment option. Methods Data of patients with single level symptomatic thoracic disc herniation treated with thoracoscopic microdiscectomy were prospectively collected over a period of 10 years. Data collection included the preoperative status and the follow-up status was 6, 12 and 24 months after surgery for every patient. Results A total of 167 single level thorascoscopic discectomies without previous surgery on the level of the procedure were included in this study. The average preoperative duration of pain symptoms was 14.3 months, myelopathic symptoms were present for an average of 16.7 months before surgery. After the procedure pain scores measured with visual analog scale (VAS) decreased by 4.4 points and the muscle strength improved by a mean of 4.6 points (American Spinal Injury Association ASIA motor score). After 2 years, 79% of the patients reported a excellent or good outcome for pain and 80% of the patients reported a excellent or good outcome for motor function. The overall complication rate was 15.6%. ConclusionsThoracoscopic microdiscectomy for single level symptomatic disc herniation is a highly effective and reliable technique, it can be performed safely with low complication rate.

BackgroundThe flavin in its FMN and FAD forms is a versatile cofactor that is involved in catalysis of most disparate types of biological reactions. These include redox reactions such as dehydrogenations, activation of dioxygen, electron transfer, bioluminescence, blue light reception, photobiochemistry (as in photolyases), redox signaling etc. Recently, hitherto unrecognized types of biological reactions have been uncovered that do not involve redox shuffles, and might involve the reduced form of the flavin as a catalyst. The present work addresses properties of reduced flavin relevant in this context.ResultsN(5)-H exchange reactions of the flavin reduced form and its pH dependence were studied using the 15N-NMR-signals of 15N-enriched, reduced flavin in the pH range from 5 to 12. The chemical shifts of the N(3) and N(5) resonances are not affected to a relevant extent in this pH range. This contrasts with the multiplicity of the N(5)-resonance, which strongly depends on pH. It is a doublet between pH 8.45 and 10.25 that coalesces into a singlet at lower and higher pH values. From the line width of the 15N(5) signal the pH-dependent rate of hydrogen exchange was deduced. The multiplicity of the 15N(5) signal and the proton exchange rates are little dependent on the buffer system used.ConclusionThe exchange rates allow an estimation of the pKa value of N(5)-H deprotonation in reduced flavin to be ≥ 20. This value imposes specific constraints for mechanisms of flavoprotein catalysis based on this process. On the other hand the pK ≈ 4 for N(5)-H protonation (to form N(5)+-H2) would be consistent with a role of N(5)-H as a base.

The apoprotein of glucose oxidase from Aspergillus niger was reconstituted with specifically lSN-and 13C-enriched FAD derivatives and investigated by "N-and I3C-NMR spectroscopy. On the basis of the "N-NMR results it is suggested that, in the oxidized state of glucose oxidase, hydrogen bonds are formed to the N(3) and N(5) positions of the isoalloxazine system. The hydrogen bond to N(3) is more pronounced than that to N(5) as compared with the respective hydrogen bonds formed between FMN and water. The resonance position of N(10) indicates a small decrease in spz hybridization compared to free flavin in water. Apparently the isoalloxazine ring is not planar at this position in glucose oxidase.Additional hydrogen bonds at the carbonyl groups of the oxidized enzyme-bound FAD were derived from the I3C-NMR results. A strong downfield shift observed for the C(4a) resonance may be ascribed in part to the decrease in sp2 hybridization at the N(10) position and to the polarization of the carbonyl groups at C(2) and C(4). The polarization of the isoalloxazine ring in glucose oxidase is more similar to FMN in water than to that of tetraacetyl-riboflavin in apolar solvents.In the reduced enzyme the N(l) position is anionic at pH 5.6. The pK, is shifted to lower pH values by at least 1 owing to the interaction of the FAD with the apoprotein.As in the oxidized state of the enzyme, a hydrogen bond is also

Mature medium chain acyl-CoA dehydrogenase isolated from pig kidney (pkMCADH) and originating from mitochondria carries a phosphate group as demonstrated by 31 P-NMR-spectroscopy and chemical analysis. Two broad resonances at -6.3 and -8 ppm are observed and are assigned to the pyrophosphate group of the cofactor FAD. A third, narrow resonance at 4.65 ppm indicates the presence of a phosphomonoester residue. Chemical analysis of intact pkMCADH shows the presence of 3 ± 0.3 phosphates, those of FAD and of an additional covalently attached phosphate. With recombinant, human wild type MCADH expressed in and purified from E. coli only the two FAD phosphates (2 ± 0.35) are found. Similarly, pkMCADH which has been converted to the apoenzyme and reconstituted to holoenzyme also contains 2 ± 0.4 phosphates. The covalently bound phosphate can be hydrolyzed by phosphatase and subsequently removed by dialysis. The phosphate group has no detectable effect on the catalytic activity of the MCADH measured with artificial and natural electron acceptors such as pig electron transferring flavoprotein. However, phosphorylation has a marked effect on protein solubility which is ffi5-fold lower for the dephosphorylated protein.

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