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BackgroundGlycerol is a major byproduct of the biodiesel industry and can be converted to 1,3-propanediol (1,3-PDO) by microorganisms through a two-step enzymatic reaction. The production of 1,3-PDO from glycerol using microorganisms is accompanied by formation of unwanted byproducts, including lactate and 2,3-butanediol, resulting in a low-conversion yield.ResultsKlebsiella pneumoniae was metabolically engineered to produce high-molar yield of 1,3-PDO from glycerol. First, the pathway genes for byproduct formation were deleted in K. pneumoniae. Then, glycerol assimilation pathways were eliminated and mannitol was co-fed to the medium. Finally, transcriptional regulation of the dha operon were genetically modified for enhancing 1,3-propanediol production. The batch fermentation of the engineered strain with co-feeding of a small amount of mannitol yielded 0.76 mol 1,3-PDO from 1 mol glycerol.ConclusionsKlebsiella pneumoniae is useful microorganism for producing 1,3-PDO from glycerol. Implemented engineering in this study successfully improved 1,3-PDO production yield, which is significantly higher than those reported in previous studies.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1100-5) contains supplementary material, which is available to authorized users.

Background and PurposeDiabetes mellitus (DM) has been proposed as a risk factor for carpal tunnel syndrome (CTS), but this remains controversial. We investigated the association between DM and CTS using both ultrasonography (US) and nerve conduction study (NCS) data.MethodsWe analyzed a prospectively recruited database of neuromuscular US and medical records of subjects who had undergone NCSs and electromyography for symptoms suggestive of CTS. Subjects were assigned to the follow groups: Group I, CTS with DM; Group II, CTS without DM; Group III, no CTS with DM; and Group IV, no CTS without DM. US cross-sectional area (CSA) and NCS measurements at the median nerve (MN) were compared among groups. We used a general linear mixed model to adjust for statistically significant covariates.ResultsThe 230 participants comprised 22, 83, 19, and 106 in Groups I–IV, respectively. In multivariate analyses, the MN action potential amplitude in females was the only variable that was significantly associated with DM (p<0.001). Groups with DM tended to have a longer latency, smaller amplitude, and lower conduction velocity in the NCSs compared to groups without DM. The measured US CSA values did not differ significantly among the groups.ConclusionsNCS measurements of the MN tended to differ between DM and non-DM patients regardless of the presence or absence of CTS. However, US did not reveal any statistically significant relationship between CTS and DM.

Objective This study aimed to investigate the utility of facial nerve ultrasonography in the functional and structural assessment of early-stage Bell’s palsy and the prognostic value of facial nerve ultrasonography in Bell’s palsy. Study Design Prospective longitudinal study. Setting Single center, a university-affiliated neurology clinic. Subjects and Methods Patients with unilateral Bell’s palsy who had visited our clinic within 3 days of symptom onset were enrolled in this study. Demographic information and House-Brackmann grade were collected. Electrophysiologic studies and facial nerve ultrasonography were then performed. The facial nerves on each side were scanned longitudinally with a 5- to 12-MHz probe. The diameter of the facial nerves with and without the sheath was measured at the proximal and distal portions. Follow-up examinations, including House-Brackmann grade analysis, electrophysiologic studies, and facial nerve ultrasonography, were performed after 2 months. Results Fifty-four patients with unilateral Bell’s palsy were enrolled, and 22 underwent the follow-up examinations. The diameters of the facial nerves were larger on the affected side than on the unaffected side at the proximal and distal portions ( P < .01). On the affected side, the enlarged facial nerve at the proximal portion had decreased in size after 2 months ( P < .05). The initial ultrasonography findings were positively correlated with the initial severity of Bell’s palsy, but they did not predict prognosis. Conclusion Ultrasonography could be a useful tool for evaluating the facial nerve in Bell’s palsy. Nevertheless, further studies are needed to demonstrate its prognostic value.