Characterization of Mixtures of Alkyl Polyglycosides (Plantacare) by Liquid Chromatography-Electrospray Ionization Quadrupole Time-of-Flight Mass Spectrometry

No HeadingPurpose. Industrial products of alkyl polyglycosides (APGs) are widely used as well tolerated surfactants in washing and cleaning agents. APGs belong to the class of nonionic surfactants and are mixtures of molecules consisting of a hydrocarbon chain with Y carbon atoms linked to X sugar residues. Physicochemical properties of APG products strongly depend on the molecular composition. Therefore, a detailed analytical investigation of technical-grade APGs is presented.Methods. Complex mixtures of alkyl/alkenyl polyglycosides (APGs, Plantacare) and mixtures of APGs with other surfactants were analyzed by reversed-phase liquid chromatography-electrospray ionization quadrupole time-of-flight mass spectrometry (LC/ESI-QTOF-MS) using methanol-water as mobile phase and gradient elution.Results. Analytes were separated according to the chain length of the alkyl homologs. Under the soft ionization of the ESI technique, mainly [M+Na]⁺ ions were observed, which proved to be very stable. Additionally [M+H]⁺ ions were detected. The QTOF mass spectrometer allows to identify even high molecular mass components in the mixtures, and APGs up to eight sugar residues were found. From these data, the alkyl/alkenyl chain lengths and the degree of oligomerization of the sugar moiety for different technical-grade APGs were calculated. Using MS/MS experiments, additional structural and chemical information was obtained.Conclusions. The presented LC/ESI-QTOF-MS approach allows to analyze and characterize various APG products, such as Plantacare. The ability of this LC/ESI-QTOF-MS approach to analyze mixtures of APGs with other surfactants is demonstrated.     

Acupuncture of specific points influences cortical auditory evoked potentials--a volunteer crossover study

Specificity of acupoints remains a crucial question in acupuncture research. The aim was to investigate whether acupuncture of specific points influences the Cortical Auditory Evoked Potentials (CAEP). Ten healthy volunteers were enrolled in this study according to inclusion criteria. One of 4 acupoints: TH3, GB43 (both claimed as specific for auditory system by Traditional Chinese Medicine) and non-specific points H7 and ST44, was stimulated during one session. Each volunteer received 4 sessions of acupuncture with an interval of 1 week between the sessions. The latencies and amplitudes of CAEP were registered before and after the acupuncture during each session. The mean peak latencies of P2 component decreased after stimulation of TH3 by 11 ms and GB43 by 14 ms whereas the peak latencies of N2 component increased after stimulation of TH3 by 9 ms and GB43 by 4 ms compared to baseline values (p<0.05). The stimulation of H7 and ST44 did not produce any changes. These findings confirm the specificity of acupuncture points TH3 and GB43 in relation to auditory system.     

Pork intake and human papillomavirus‐related disease

Clinical and ecological evidence supporting an association between human papillomavirus (HPV)‐related tumors and dietary factors are presented. Abstinence from high intake of fried pork (600–1,000 g/day) was associated with regression of an urethral condyloma in a healthy 19‐year‐old man treated with interferon gamma. International correlations suggest that pork intake is positively associated with incidence of cervical cancer, a disease also related to HPV. Pork meat or dietary factors associated with pork meat consumption may be involved in the development of HPV‐related diseases.     

Dynamic structure of lipid-bound synaptobrevin suggests a nucleation-propagation mechanism for trans-SNARE complex formation

The synaptic vesicle protein synaptobrevin engages with syntaxin and SNAP-25 to form the SNARE complex, which drives membrane fusion in neuronal exocytosis. In the SNARE complex, the SNARE motif of synaptobrevin forms a 55-residue helix, but it has been assumed to be mostly unstructured in its prefusion form. NMR data for full-length synaptobrevin in dodecylphosphocholine micelles reveals two transient helical segments flanked by natively disordered regions and a third more stable helix. Transient helix I comprises the most N-terminal part of the SNARE motif, transient helix II extends the SNARE motif into the juxtamembrane region, and the more stable helix III is the transmembrane domain. These helices may have important consequences for SNARE complex folding and fusion: helix I likely forms a nucleation site, the C-terminal disordered SNARE motif may act as a folding arrest signal, and helix II likely couples SNARE complex folding and fusion.