Shiga toxin (STx) belongs to the AB(5) toxin family and is transiently localized in the periplasm before secretion into the extracellular milieu. While producing outer membrane vesicles (OMVs) containing only A subunit of the toxin (STxA), we created specific STx1B- and STx2B-deficient mutants of E. coli O157:H7. Surprisingly, STxA subunit was absent in the OMVs and periplasm of the STxB-deficient mutants. In parallel, the A subunit of heat-labile toxin (LT) of enterotoxigenic E. coli (ETEC) was absent in the periplasm of the LT-B-deficient mutant, suggesting that instability of toxin A subunit in the absence of the B subunit is a common phenomenon in the AB(5) bacterial toxins. Moreover, STx2A was barely detectable in the periplasm of E. coli JM109 when stx2A was overexpressed alone, while it was stably present when stxB was co-expressed. Compared with STx2 holotoxin, purified STx2A was degraded rapidly by periplasmic proteases when assessed for in vitro proteolytic susceptibility, suggesting that the B subunit contributes to stability of the toxin A subunit in the periplasm. We propose a novel role for toxin B subunits of AB(5) toxins in protection of the A subunit from proteolysis during holotoxin assembly in the periplasm.

ObjectivesThis clinical study was aimed to examine the effects of herbal medicine and acupuncture on early onsetessential tremor and report on the therapeutic progress. MethodsHerbal medication (Kamiyangsintang) and acupuncture were used for treatment. Also, VAS scale were used to check the improvement. ResultsThe hands tremor was relieved during 4 months of treatment. However, the symptom was aggravated after one and a half years. The patient has shown improvement after retreatment. ConclusionsThis study showed that child patient diagnosed with essential tremor who received Kamiyangsintang and acupuncture treatments was improved. However, it also can be aggravated depending on the patients and their body condition. More cases and long-term observation in relation to early onset of tremor are required.

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