Within the capsule gene complex (cps) of Neisseria meningitidis B a 5.5 kb DNA fragment encodes proteins with strong homologies to enzymes of the lipopolysaccharide biosynthetic pathway of Salmonella typhimurium and Escherichia coli, GalE, RfbB, RfbC and RfbD. A meningococcal galE mutant expressed a truncated lipooligosaccharide (LOS), which terminated at the glucose residue between inner and outer core, and a second galE gene present outside the cps cluster was found to be transcriptionally and functionally inactive and, thus, unable to complement this defect. Because of the defect in the outer core, the LOS of the galE-defective meningococcal mutant was not sialylated. In contrast, carbohydrate analysis of the LOS of an rfb-defective meningococcal mutant revealed no difference from the LOS of the wild-type strain, suggesting that the rfb genes are inactive. This was supported by Northern blot analysis, which showed that expression of the rfb gene products was transcriptionally regulated. The inability of the meningococcal galE mutant, which cannot sialylate the LOS, allowed us to investigate the significance of LOS sialylation in relation to the presence of the polysialic acid capsule. Sialylated LOS, but not the polysialic acid capsule, is necessary to confer complete serum resistance on the meningococcus by inhibition of the alternative complement pathway.
Rationale:Ectopic thyroid carcinoma within a thyroglossal duct cyst (TGDCCa) is an extremely rare entity. Thus, there is no unified appropriate therapeutic strategy, and individual approaches are controversial.Patients concerns:We report the case of a 21-year old woman who underwent Sistrunk procedure for a thyroglossal duct cyst (TGDC).Diagnoses:During histological evaluation of the resected TGDC a papillary thyroid carcinoma was found.Interventions:Due to a tumor size of 1cm and proximity to the surgical border, Sistrunk procedure was extended by total thyroidectomy, followed by radioiodine ablation.Outcomes:Except of minimal follicular hyperplasia, the histological examination of the resected thyroid gland was unsuspicious.Lessons:Therapeutic management of TGDCCa is of interdisciplinary debate due to relative infrequence of the disease and consequently lack of unified therapeutic guidelines. We suggest a personalized therapeutic approach adjusted to individual risk stratification. In young patients with small tumor size and with confirmation of TGDCCa representing the primary tumor, Sistrunk procedure alone may reflect adequate treatment. In all other cases, total thyroidectomy and radioiodine ablation should be evaluated. Overall TGDCCa have an excellent prognosis with a 5-year survival rate of more than 90%.
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