Oligosaccharides in feces of breast- and formula-fed babies

So far, little is known on the fate of oligosaccharides in the colon of breast- and formula-fed babies. Using capillary electrophoresis with laser induced fluorescence detector coupled to a mass spectrometer (CE–LIF–MSⁿ), we studied the fecal oligosaccharide profiles of 27 two-month-old breast-, formula- and mixed-fed preterm babies. The interpretation of the complex oligosaccharide profiles was facilitated by beforehand clustering the CE–LIF data points by agglomerative hierarchical clustering (AHC). In the feces of breast-fed babies, characteristic human milk oligosaccharide (HMO) profiles, showing genetic fingerprints known for human milk of secretors and non-secretors, were recognized. Alternatively, advanced degradation and bioconversion of HMOs, resulting in an accumulation of acidic HMOs or HMO bioconversion products was observed. Independent of the prebiotic supplementation of the formula with galactooligosaccharides (GOS) at the level used, similar oligosaccharide profiles of low peak abundance were obtained for formula-fed babies. Feeding influences the presence of diet-related oligosaccharides in baby feces and gastrointestinal adaptation plays an important role herein. Four fecal oligosaccharides, characterized as HexNAc-Hex-Hex, Hex-[Fuc]-HexNAc-Hex, HexNAc-[Fuc]-Hex-Hex and HexNAc-[Fuc]-Hex-HexNAc-Hex-Hex, highlighted an active gastrointestinal metabolization of the feeding-related oligosaccharides. Their presence was linked to the gastrointestinal mucus layer and the blood-group determinant oligosaccharides therein, which are characteristic for the host’s genotype.     

Specificities of Ricinus communis agglutinin 120 interaction with sulfated galactose

Lectins are used extensively as research tools to detect and target specific oligosaccharide sequences. Ricinus communis agglutinin I (RCA₁₂₀) recognizes non-reducing terminal β-d-galactose (Galβ) and its specificities of interactions with neutral and sialylated oligosaccharides have been well documented. Here we use carbohydrate arrays of sulfated Galβ-containing oligosaccharide probes, prepared from marine-derived galactans, to investigate their interactions with RCA₁₂₀. Our results showed that RCA₁₂₀ binding to Galβ1–4 was enhanced by 2-O- or 6-O-sulfation but abolished by 4-O-sulfation. The results were corroborated with competition experiments. Erythrina cristagalli lectin is also a Galβ-binding protein but it cannot accommodate any sulfation on Galβ.     

Somatic embryogenesis, scanning electron microscopy, histology and biochemical analysis at different developing stages of embryogenesis in six date palm (Phoenix dactylifera L.) cultivars

An efficient somatic embryogenesis system has been established in six date palm (Phoenix dactylifera L.) cultivars (Barhee, Zardai, Khalasah, Muzati, Shishi and Zart). Somatic embryogenesis (SE) was growth regulators and cultivars dependent. Friable embryogenic callus was induced from excised shoot tips on MS medium supplemented with various auxins particularly 2,4-dichlorophenoxyacetic acid (2,4-D, 1.5 mg 1^−l). Suspension culture increased embryogenesis potentiality. Only a-naphthaleneacetic acid (NAA, 0.5 mg 1⁻¹) produced somatic embryos in culture. Somatic embryos germinated and converted into plantlets in N⁶-benzyladenine (BAP, 0.75 mg 1^−l) added medium following a treatment with thidiazuron (TDZ, 1.0 mg 1^−l) for maturation. Scanning electron microscopy showed early stages of somatic embryo particularly, globular types, and was in masses. Different developing stages of embryogenesis (heart, torpedo and cotyledonary) were observed under histological preparation of embryogenic callus. Biochemical screening at various stages of somatic embryogenesis (embryogenic callus, somatic embryos, matured, germinated embryos and converted plantlets) of date palm cultivars has been conducted and discussed in detail. The result discussed in this paper indicates that somatic embryos were produced in numbers and converted plantlets can be used as a good source of alternative propagation. Genetic modification to the embryo precursor cell may improve the fruit quality and yield further.     

Structural studies of the lipopolysaccharide from Haemophilus parainfluenzae strain 20

Haemophilus parainfluenzae is a Gram-negative bacterium that colonizes the upper respiratory tract of humans and is a part of normal flora. In this study, we investigated the lipopolysaccharide (LPS) expressed by H. parainfluenzae strain 20. Using NMR and MS techniques on LPS, oligosaccharide samples and lipid A, the structures for O-antigen, core oligosaccharide and lipid A could be established. It was found that the biological repeating unit of the O-antigen is →4)-α-d-GalpNAc-(1→P→6)-β-d-Glcp-(1→3)-α-d-FucpNAc4N-(1→, in which d-FucpNAc4N is 2-acetamido-4-amino-2,4,6-trideoxy-d-galactose. This sugar is in β-configuration when linked to O-4 of the glucose residue of β-d-Galp-(1→2)-l-α-d-Hepp-(1→2)-[PEtn→6]-l-α-d-Hepp-(1→3)-[β-d-Glcp-(1→4)]-l-α-d-Hepp-(1→5)-[PPEtn→4]-α-Kdo-(2→6)-lipid A. LPS from a wbaP mutant of H. parainfluenzae strain 20 did not contain an O-antigen, consistent with the wbaP gene product being required for expression of O-antigen in fully extended LPS.     

Expression of a new disialyllacto structure in the lipopolysaccharide of non-typeable Haemophilus influenzae

The structure of lipopolysaccharide (LPS) expressed by non-typeable Haemophilus influenzae (NTHi) strains 1008 and 1247 has been investigated by mass spectrometry and NMR analyses on O-deacylated LPS and core oligosaccharide material. Both strains express the conserved triheptosyl inner core, [l-α-d-Hepp-(1→2)-[PEtn→6]-l-α-d-Hepp-(1→3)-l-α-d-Hepp-(1→5)-[PPEtn→4]-α-Kdo-(2→6)-Lipid A] with PCho→6)-β-d-Glcp (GlcI) substituting the proximal heptose (HepI) at O-4. Strain 1247 expresses the common structural motifs of H. influenzae; globotetraose [β-d-GalpNAc-(1→3)-α-d-Galp-(1→4)-β-d-Galp-(1→4)-β-d-Glcp-(1→] and its truncated versions globoside [α-d-Galp-(1→4)-β-d-Galp-(1→4)-β-d-Glcp-(1→] and lactose [β-d-Galp-(1→4)-β-d-Glcp-(1→] linked to the terminal heptose of the inner core and GlcI. A genetically distinct NTHi strain, 1008, expresses identical structures to strain 1247 with the exception that it lacks GalNAc. A lpsA mutant of strain 1247 expressed LPS of reduced complexity that facilitated unambiguous structural determination of the oligosaccharide from HepI. By CE-ESI-MS/MS we identified disialylated glycoforms indicating disialyllactose [α-Neu5Ac-(2→8)-α-Neu5Ac-(2→3)-β-d-Gal-(1→4)-β-d-Glcp-(1→] as an extension from GlcI which is a novel finding for NTHi LPS.     

Importance of cholesterol and oxysterols metabolism in the pharmacology of tamoxifen and other AEBS ligands

Tamoxifen is one of the major drugs used for the hormonotherapy of estrogen receptor positive breast cancers. However, its therapeutic efficacy can be limited by acquired resistance and tumor recurrence can occur after several years of treatment. Tamoxifen is known as the prototypical modulator of estrogen receptors, but other targets have been identified that could account for its pharmacology. In particular, tamoxifen binds with high affinity to the microsomal antiestrogen binding site (AEBS) and inhibits cholesterol esterification at therapeutic doses. We have recently shown that the AEBS was a hetero-oligomeric complex composed of 3β-hydroxysterol-Δ(8)-Δ(7)-isomerase and 3β-hydroxysterol-Δ(7)-reductase, that binds different structural classes of ligands, including selective estrogen receptor modulators, several sigma receptor ligands, poly-unsaturated fatty acids and ring B oxysterols. We established a link between the modulation of cholesterol metabolism by tamoxifen and other AEBS ligands and their capacity to induce breast cancer cell differentiation, apoptosis and autophagy. Moreover, we showed that the AEBS carries out cholesterol-5,6-epoxide hydrolase activity and established that cholesterol-5,6-epoxide hydrolase is a new target for tamoxifen and other AEBS ligands. Finally in this review, we report on recent data from the literature showing how the modulation of cholesterol and oxysterol metabolism can be linked to the antitumor and chemopreventive properties of tamoxifen, and give new perspectives to improve the clinical outcome of the hormonotherapy of breast cancers.     

Nitric oxide modulates the expression of endothelial cell adhesion molecules involved in angiogenesis and leukocyte recruitment

Tumor angiogenesis and immune response have in common to be cell recognition mechanisms, which are based on specific adhesion molecules and dependent on nitric oxide (NO^•). The aim of the present study is to deepen the mechanisms of angiogenesis and inflammation regulation by NO^• to find out the molecular regulation processes that govern endothelial cell permeability and leukocyte transmigration.Effects of NO^•, either exogenous or produced in hypoxic conditions, were studied on microvascular endothelial cells from skin and lymph node because of their strong involvement in melanoma progression. We found that NO^• down-regulation of pseudo-vessel formation was linked to a decrease in endothelial cell ability to adhere to each other which can be explain, in part, by the inhibition of PECAM-1/CD31 expression. On the other hand, NO^• was shown to be able to decrease leukocyte adhesion on an endothelial monolayer, performed either in static or in rolling conditions, and to modulate differentially CD34, ICAM-1/CD54, ICAM-2/CD102 and VCAM-1/CD106 expression.In conclusion, during angiogenesis and leukocyte recruitment, NO^• regulates cell interactions by controlling adhesion molecule expression and subsequently cell adhesion. Moreover, each endothelial cell type presents its own organospecific response to NO^•, reflecting the functions of the tissue they originate from.