Detection by gas chromatography of 3-deoxy-D-manno-2-octulosonic acid and L-glycero-D-manno-heptose in whole cells of Neisseria elongata

Derivatization of carbohydrates for GC and GC-MS analyses

GC and GC-MS are excellent techniques for the analysis of carbohydrates; nevertheless the preparation of adequate derivatives is necessary. The different functional groups that can be found and the diversity of samples require specific methods. This review aims to collect the most important methodologies currently used, either published as new procedures or as new applications, for the analysis of carbohydrates. A high diversity of compounds with diverse functionalities has been selected: neutral carbohydrates (saccharides and polyalcohols), sugar acids, amino and iminosugars, polysaccharides, glycosides, glycoconjugates, anhydrosugars, difructose anhydrides and products resulting of Maillard reaction (osuloses, Amadori compounds). Chiral analysis has also been considered, describing the use of diastereomers and derivatives to be eluted on chiral stationary phases.

Aldose reductase inhibitor counteracts the attenuated adhesion of human corneal epithelial cells induced by high glucose through modulation of MMP-10 expression

AIMS

We investigated the preventive effect of aldose reductase inhibitor (ARI) on the adhesion of SV40-transformed human corneal epithelial cells (HCECs) exposed to high glucose, and the underlying mechanism focusing on the role of matrix metalloproteinase (MMP)-10.

METHODS

HCECs were cultured in medium containing a normal (5.5 mM) or high (31.2 mM) concentration of D-glucose in the presence or absence of ARI, fidarestat. Cell attachment ability was evaluated by short-term adhesion assay. The levels of intracellular polyol were measured by liquid-gas chromatography. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR), and Western blotting were used to determine the expression levels.

RESULTS

Decreased attachment activity and increased accumulation of polyol induced by exposure to high glucose were abrogated by ARI. Supply of recombinant MMP-10 decreased integrin alpha3beta1-expression and cell adhesion. The expression level of MMP-10 was enhanced at both protein and mRNA levels by exposure to high glucose, while that of integrin alpha3beta1 was decreased at the protein level, but remained unchanged at the mRNA level. These alterations in the expression levels of MMP-10 and integrin alpha3beta1 were normalized by ARI.

CONCLUSIONS

ARI counteracts the decreased adhesion of HCECs induced by high glucose exposure, through the modulation of the expression of MMP-10.

Streptozotocin-induced diabetes causes metabolic changes and alterations in neurotrophin content and retrograde transport in the cervical vagus nerve

Abnormal availability of neurotrophins, such as nerve growth factor (NGF), has been implicated in diabetic somatosensory polyneuropathy. However, the involvement of neurotrophins in diabetic neuropathy of autonomic nerves, particularly the vagus nerve which plays a critical role in visceral afferent and in autonomic motor functions, is unknown. To assess the effects of hyperglycemia on the neurotrophin content and transport in this system, cervical vagus nerves of streptozotocin (STZ)-induced diabetic rats were studied at 8, 16, and 24 weeks after the induction of diabetes. Elevations in vagus nerve hexose (glucose and fructose) and polyol levels (sorbitol), and their normalization with insulin treatment, verified that the STZ treatment resulted in hyperglycemia-induced metabolic abnormalities in the nerve. Neurotrophin (NGF and neurotrophin-3; NT-3) content and axonal transport were assessed in the cervical vagus nerves from nondiabetic control rats, STZ-induced diabetic rats, and diabetic rats treated with insulin. The NGF, but not the NT-3, content of intact vagus nerves from diabetic rats was increased at 8 and 16 weeks (but not at 24 weeks). Using a double-ligation model to assess the transport of endogenous neurotrophins, the retrograde transport of both NGF and NT-3 was found to be significantly reduced in the cervical vagus nerve at later stages of diabetes (16 and 24 weeks). Anterograde transport of NGF or NT-3 was not apparent in the vagus nerve of diabetic or control rats. These data suggest that an increase in vagus nerve NGF is an early, but transient, response to the diabetic hyperglycemia and that a subsequent reduction in neuronal access to NGF and NT-3 secondary to decreased retrograde axonal transport may play a role in diabetes-induced damage to the vagus nerve.

Identification of an immunoreactive non-proteinaleous component in Borrelia burgdorferi

Investigations of immunoblots using Borrelia burgdorferi antigen demonstrated that a band, migrating faster than the bromophenol blue front in sodium dodecyl sulfate-gel electrophoresis, reacted strongly with sera containing anti-Borrelia burgdorferi antibodies preferentially of the IgG class. Extraction of this antigenic component and chemical analyses showed that the substance was composed mainly of fatty acids and carbohydrates. Typical structures of classical lipooolysaccharides such as 3-deoxy-D-manno-2-octulosonic acid, hydroxy fatty acids or lipid A could not be detected.

Rapid identification of Haemophilus influenzae serovar b by gas liquid chromatography using carbohydrate fingerprints

Carbohydrates from whole-cell hydrolysates of 18 strains of the species Haemophilus influenzae (5 strains belonging to serovar b) were analysed by gas-liquid chromatography. The identity of the carbohydrate components was confirmed by comparison with the retention times of reference sugars and by gas chromatography mass spectrometry. Evidence was obtained that Haemophilus influenzae serovar b can easily be identified by the presence of one large peak representing ribitol. The method described can be routinely applied in bacteriological laboratories equipped with a gas chromatograph. It gives results within approximately 4 h, it is reproducible and easy to perform. Even single colonies isolated directly from agar plates can be used for analysis without further subculturing.