Sequential monitoring of 724 sera for antibodies to a neoantigen based on phenolic glycolipid-I (PGL-I) and native lipoarabinomannan (LAM) in 90 leprosy patients undergoing therapy in San Francisco was conducted. Untreated lepromatous patients frequently (91%) had significant antibodies to both moieties. Antibodies were less frequently found in tuberculoid patients (74% to neoantigen and 37% to LAM). In the first 3 years of treatment, average serum antibodies to both moieties fell significantly. Antibodies to LAM fell during each of the first 4 years of therapy, but decreasing antibody levels to the PGL-I neoantigen did not appear to fall consistently after the third year of treatment. A wide variation in the rate of fall of serum antibodies was noted. Sequential changes in the amounts of serum antibodies to the neoantigen and LAM in general paralleled one another but were at times discrepant. Both in San Francisco and Malaysia, skin-smear negative, long-term treated, lepromatous leprosy patients frequently harbored significant antibodies to both PGL-I and LAM.
Anti-idiotype (Id) vaccine therapy has been tested and shown to be effective, in several animal models, for triggering the immune system to induce specific and protective immunity against bacterial, viral and parasitic infections. The administration of anti-Id antibodies as surrogate tumor-associated antigens (TAA) also represents another potential application of the concept of the Id network. Limited experience in human trials using anti-Id to stimulate immunity against tumors has shown promising results. In this "counter-point" article, we discuss our own findings showing the potential of anti-Id antibody vaccines to be novel therapeutic approaches to various human cancers and also discuss where anti-Id vaccines may perform better than traditional multiple-epitope antigen vaccines.
Two novel glycolipids have been synthesized and their phase behaviour studied. They have been characterized using FT-IR, FAB and 13C NMR and 1H NMR to ensure the purity of novel glycolipids. The two glycolipids are distinguished based on the head group of glycolipids (monosaccharide/glucose and disaccharide/maltose). These two novel glycolipids have been used as surfactant to perform two phase diagrams. Phase behaviours that have been investigated are 2-hexyldecyl-beta-D-glucopyranoside (2-HDG)/n-octane/water ternary system and 2-hexyldecyl-beta-D-maltoside (2-HDM)/n-octane/water ternary system. SAXS and polarizing optical microscope have been used to study the phase behaviours of these two surfactants in ternary phase diagram. Study of effect of the head group on branched-alkyl chain surfactants in ternary system is a strategy to derive the structure-property relationship. For comparison, 2-HDM and 2-HDG have been used as surfactant in the same ternary system. The phase diagram of 2-hexyldecyl-beta-D-maltoside/n-octane/water ternary system exhibited a Lalpha phase at a higher concentration regime, followed with two phases and a micellar solution region in a lower concentration regime. The phase diagram of 2-HDG/water/n-octane ternary system shows hexagonal phase, cubic phase, rectangular ribbon phase, lamellar phase, cubic phase as the surfactant concentration increase.
Water-driven self-assembly of lipids displays a variety of liquid crystalline phases that are crucial for membrane functions. Herein, we characterize the temperature-induced phase transitions in two compositions of an aqueous self-assembly system of the octyl β-D-glucoside (βGlcOC(8)) system, using steady-state and time-resolved fluorescence measurements. The phase transitions hexagonal ↔ micellar and cubic ↔ lamellar were investigated using tryptophan (Trp) and two of its ester derivatives (Trp-C(4) and Trp-C(8)) to probe the polar headgroup region and pyrene to probe the hydrophobic tail region. The polarity of the headgroup region was estimated to be close to that of simple alcohols (methanol and ethanol) for all phases. The pyrene fluorescence indicates that the pyrene molecules are dispersed among the tails of the hydrophobic region, yet remain in close proximity to the polar head groups. Comparing the present results with our previously reported one for βMaltoOC(12), increasing the tail length of the hexagonal phase from C(8) to C(12) leads to less interaction with pyrene, which is attributed to the more random and wobbling motion of the longer alkyl tail. We measured a reduction (more hydrophobic) in the ratio of the vibronic peak intensities of pyrene (I(1)/I(3)) for the lamellar phase compared to that of the cubic phase. The higher polarity in the cubic phase can be correlated to the nature of its interface, which curves toward the bulk water. This geometry also explains the slight reduction in polarity of the headgroup region compared to the other phases. Upon the addition of Trp-C(8), the fluorescence lifetime of pyrene is reduced by 28% in the lamellar and cubic phases, whereas the I(1)/I(3) value is only slightly reduced. The results reflect the dominant role of dynamic interaction mechanism between the C(8) chain of Trp-C(8) and pyrene. This mechanism may be important for these two phases since they participate in the process of membrane fusion. Both lipid compositions show completely reversible temperature-induced phase transitions, reflecting the thermodynamic equilibrium structures of their mesophases. Probing both regions of the different lipid phases reveals a large degree of heterogeneity and flexibility of the lipid self-assembly. These properties are crucial for carrying out different biological functions such as the ability to accommodate various molecular sizes.
Glycolipids form materials of considerable potential for a wide range of surfactant and thin film applications. Understanding the effect of glycolipid covalent structure on the properties of their thermotropic and lyotropic assemblies is a key step toward rational design of new glycolipid-based materials. Here, we perform molecular dynamics simulations of anhydrous bilayers of dodecyl β-maltoside, dodecyl β-cellobioside, dodecyl β-isomaltoside, and a C(12)C(10) branched β-maltoside. Specifically, we examine the consequences of chain branching and headgroup identity on the structure and dynamics of the lamellar assemblies. Chain branching of the glycolipid leads to measurable differences in the dimensions and interactions of the lamellar assembly, as well as a more fluid-like hydrophobic chain region. Substitution of the maltosyl headgroup of βMal-C(12) by an isomaltosyl moiety leads to a significant decrease in bilayer spacing as well as a markedly altered pattern of inter-headgroup hydrogen bonding. The distinctive simulated structures of the two regioisomers provide insight into the difference of ~90 °C in their observed clearing temperatures. For all four simulated glycolipid systems, with the exception of the sn-2 chain of the branched maltoside, the alkyl chains are ordered and exhibit a distinct tilt, consistent with recent crystallographic analysis of a branched chain Guerbet glycoside. These insights into structure-property relationships from simulation provide an important molecular basis for future design of synthetic glycolipid materials.
A theoretical study of a series of five glucose based glycolipid crown ethers and their complexes with Na(+) and K(+) was performed using the density functional theory with B3LYP/6-31 G* to obtain the optimized geometrical structures and electronic properties. The local nucleophilicity of the five molecules was investigated using Fukui function, while the global nucleophilicity was calculated from the ionization potential and electron affinity. The structures and coordination of the complexes were studied to identify the best match of the glycolipid crown ethers with cations. In general, it was found that the oxygen atoms pairs O2 and O3 (or O4 and O6) on the sugar ring are constrained from moving toward the cation, which results in a weaker O-cation coordination strength for the oxygen pair compared to the other oxygen atoms in the crown ether ring. The thermodynamic properties of the binding of the complexes and the exchange reaction in gas phase were evaluated. The cation selectivity pattern among the five molecules was in good agreement with the experiment.
A biosurfactant-producing and hydrocarbon-utilizing bacterium, Pseudomonas aeruginosa USM-AR2, was used to assist conventional distillation. Batch cultivation in a bioreactor gave a biomass of 9.4 g L(-1) and rhamnolipid concentration of 2.4 g L(-1) achieved after 72 h. Biosurfactant activity (rhamnolipid) was detected by the orcinol assay, emulsification index and drop collapse test. Pretreatment of crude oil TK-1 and AG-2 with a culture of P. aeruginosa USM-AR2 that contains rhamnolipid was proven to facilitate the distillation process by reducing the duration without reducing the quality of petroleum distillate. It showed a potential in reducing the duration of the distillation process, with at least 2- to 3-fold decreases in distillation time. This is supported by GC-MS analysis of the distillate where there was no difference between compounds detected in distillate obtained from treated or untreated crude oil. Calorimetric tests showed the calorie value of the distillate remained the same with or without treatment. These two factors confirmed that the quality of the distillate was not compromised and the incubation process by the microbial culture did not over-degrade the oil. The rhamnolipid produced by this culture was the main factor that enhanced the distillation performance, which is related to the emulsification of hydrocarbon chains in the crude oil. This biotreatment may play an important role to improve the existing conventional refinery and distillation process. Reducing the distillation times by pretreating the crude oil with a natural biosynthetic product translates to energy and cost savings in producing petroleum products.
Dysregulated metabolism is implicated in obesity and other disease conditions like type 2 diabetes mellitus and cardiovascular diseases, which are linked to abnormalities of peroxisome proliferator-activated receptor gamma (PPARγ). PPARγ has been the focus of much research aimed at managing these diseases. Also, germinated brown rice (GBR) is known to possess antidiabetic, antiobesity and hypocholesterolemic effects. We hypothesized that GBR bioactive compounds may mediate some of the improvements in metabolic indices through PPARγ modulation. Cultured HEP-G2 cells were treated with 50 ppm and 100 ppm of extracts from GBR (GABA, ASG and oryzanol) after determination of cell viabilities using MTT assays. Results showed that all extracts upregulated the expression of the PPARγ. However, combination of all three extracts showed downregulation of the gene, suggesting that, in combination, the effects of these bioactives differ from their individual effects likely mediated through competitive inhibition of the gene. Upregulation of the gene may have therapeutic potential in diabetes mellitus and cardiovascular diseases, while its downregulation likely contributes to GBR's antiobesity effects. These potentials are worth studying further.
Aiming for new glycolipids with enhanced chemical stability and close structural similarity to natural cell membrane lipids for the development of a drug delivery system, we have synthesized double amide analogs of glyco-glycerolipids. The synthesis applied a Staudinger reaction based coupling of a 1,3-diazide with fatty acid chlorides. While the concept furnished the desired glucosides in reasonable yields, the corresponding lactosides formed a tetrahydropyrimidine based 1:1 coupling product instead. This unexpected coupling result likely originates from steric hindrance at the iminophosphorane intermediate and provides an interesting core structure for potentially bioactive surfactants. The assembly behavior of both glycolipid types was investigated by optical polarizing microscopy, DSC and surface tension studies.
Synthetic branched-chain glycolipids are suitable as model systems in understanding biological cell membranes, particularly because certain natural lipids possess chain branching. Herein, four branched-chain glycopyranosides, namely, 2-hexyl-decyl-α-D-glucopyranoside (α-Glc-OC10C6), 2-hexyl-decyl-β-D-glucopyranoside (β-Glc-OC10C6), 2-hexyl-decyl-α-D-galactopyranoside (α-Gal-OC10C6), and 2-hexyl-decyl-β-D-galactopyranoside (β-Gal-OC10C6), with a total alkyl chain length of 16 carbon atoms have been synthesized, and their phase behavior has been studied. The partial binary phase diagrams of these nonionic surfactants in water were investigated by optical polarizing microscopy (OPM) and small-angle X-ray scattering (SAXS). The introduction of chain branching in the hydrocarbon chain region is shown to result in the formation of inverse structures such as inverse hexagonal and inverse bicontinuous cubic phases. A comparison of the four compounds showed that they exhibited different polymorphism, especially in the thermotropic state, as a result of contributions from anomeric and epimeric effects according to their stereochemistry. The neat α-Glc-OC10C6 compound exhibited a lamellar (Lα) phase whereas dry α-Gal-OC10C6 formed an inverse bicontinuous cubic Ia3d (QII(G)) phase. Both β-anomers of glucoside and galactoside adopted the inverse hexagonal phase (HII) in the dry state. Generally, in the presence of water, all four glycolipids formed inverse bicontinuous cubic Ia3d (QII(G)) and Pn3m (QII(D)) phases over wide temperature and concentration ranges. The formation of inverse nonlamellar phases by these Guerbet branched-chain glycosides confirms their potential as materials for novel biotechnological applications such as drug delivery and crystallization of membrane proteins.
Fully atomistic molecular dynamics simulation studies of thermotropic bilayers were performed using a set of glycosides namely n-octyl-β-D-glucopyranoside (β-C8Glc), n-octyl-α-D-glucopyranoside (α-C8Glc), n-octyl-β-D-galactopyranoside (β-C8Gal), and n-octyl-α-D-galactopyranoside (α-C8Gal) to investigate the stereochemical relationship of the epimeric/anomeric quartet liner glycolipids with the same octyl chain group. The results showed that, the anomeric stereochemistry or the axial/equatorial orientation of C1-O1 (α/β) is an important factor controlling the area and d-spacing of glycolipid bilayer systems in the thermotropic phase. The head group tilt angle and the chain ordering properties are affected by the anomeric effect. In addition, the L(C) phase of β-C8Gal, is tilting less compared to those in the fluid L(α). The stereochemistry of the C4-epimeric (axial/equatorial) and anomeric (α/β) centers simultaneously influence the inter-molecular hydrogen bond. Thus, the trend in the values of the hydrogen bond for these glycosides is β-C8Gal > α-C8Glc > β-C8Glc > α-C8Gal. The four bilayer systems showed anomalous diffusion behavior with an observed trend for the diffusion coefficients; and this trend is β-C8Gal > β-C8Glc > α-C8Gal > α-C8Glc. The "bent" configuration of the α-anomer results in an increase of the hydrophobic area, chain vibration and chain disorganization. Since thermal energy is dispensed more entropically for the chain region, the overall molecular diffusion decreases.
The effect of incorporating new nonionic glycolipid surfactants on the properties of a model water/nonionic surfactant/oil nano-emulsion system was investigated using branched-chain alkyl glycosides: 2-hexyldecyl-β(/α)-D-glucoside (2-HDG) and 2-hexyldecyl-β(/α)-D-maltoside (2-HDM), whose structures are closely related to glycero-glycolipids. Both 2-HDG and 2-HDM have an identical hydrophobic chain (C16), but the former consists a monosaccharide glucose head group, in contrast to the latter which has a disaccharide maltose unit. Consequently, their hydrophilic-lipophilic balance (HLB) is different. The results obtained have shown that these branched-chain alkyl glycosides affect differently the stability of the nano-emulsions. Compared to the model nano-emulsion, the presence of 2-HDG reduces the oil droplet size, whereas 2-HDM modify the properties of the model nano-emulsion system in terms of its droplet size and storage time stability at high temperature. These nano-emulsions have been proven capable of encapsulating ketoprofen, showing a fast release of almost 100% in 24h. Thus, both synthetically prepared branched-chain alkyl glycosides with mono- and disaccharide sugar head groups are suitable as nano-emulsion stabilizing agents and as drug delivery systems in the future.
A diverse surfactant, including the nonionic Tween 80 and Brij 30, the anionic sodium dodecyl sulphate, the cationic surfactant Tetradecyltrimethylammonium bromide, and biosurfactant Rhamnolipid were investigated under fluorine-enriched medium by Armilaria sp. F022. The cultures were performed at 25 °C in malt extract medium containing 1 % of surfactant and 5 mg/L of fluorene. The results showed among the tested surfactants, Tween-80 harvested the highest cell density and obtained the maximum specific growth rate. This due Tween-80 provide a suitable carbon source for fungi. Fluorane was also successfully eliminated (>95 %) from the cultures within 30 days in all flasks. During the experiment, laccase production was the highest among other enzymes and Armillaria sp. F022-enriched culture containing Non-ionic Tween 80 showed a significant result for laccase activity (1,945 U/L). The increased enzyme activity was resulted by the increased biodegradation activity as results of the addition of suitable surfactants. The biotransformation of fluorene was accelerated by Tween 80 at the concentration level of 10 mg/L. Fluorene was initially oxidized at C-2,3 positions resulting 9-fluorenone. Through oxidative decarboxylation, 9-fluorenone subjected to meta-cleavage to form salicylic acid. One metabolite detected in the end of experiment, was identified as catechol. Armillaria sp. F022 evidently posses efficient, high effective degrader and potential for further application on the enhanced bioremediation technologies for treating fluorene-contaminated soil.
A fed-batch strategy was established based on the maximum substrate uptake rate (MSUR) of Pseudomonas aeruginosa USM-AR2 grown in diesel to produce rhamnolipid. This strategy matches the substrate feed rates with the substrate demand based on the real-time measurements of dissolved oxygen (DO). The MSUR was estimated by determining the time required for consumption of a known amount of diesel. The MSUR trend paralleled the biomass profile of Ps. aeruginosa USM-AR2, where the MSUR increased throughout the exponential phase indicating active substrate utilization and then decreased when cells entered stationary phase. Rhamnolipid yield on diesel was enhanced from 0·047 (g/g) in batch to 0·110 (g/g) in pulse-pause fed-batch and 0·123 (g/g) in MSUR fed-batch. Rhamnolipid yield on biomass was also improved from 0·421 (g/g) in batch, 3·098 (g/g) in pulse-pause fed-batch to 3·471 (g/g) using MSUR-based strategy. Volumetric productivity increased from 0·029 g l(-1) h(-1) in batch, 0·054 g l(-1) h(-1) in pulse-pause fed-batch to 0·076 g l(-1) h(-1) in MSUR fed-batch.
To comprehensively investigate the relationship between antibodies to single glycolipids and their complexes and Guillain-Barré syndrome subtypes and clinical features.
Glycolipid, found commonly in membranes, is also a liquid crystal material which can self-assemble without the presence of a solvent. Here, the dielectric and conductivity properties of three synthetic glycolipid thin films in different thermotropic liquid crystal phases were investigated over a frequency and temperature range of (10(-2)-10(6) Hz) and (303-463 K), respectively. The observed relaxation processes distinguish between the different phases (smectic A, columnar/hexagonal, and bicontinuous cubic Q) and the glycolipid molecular structures. Large dielectric responses were observed in the columnar and bicontinuous cubic phases of the longer branched alkyl chain glycolipids. Glycolipids with the shortest branched alkyl chain experience the most restricted self-assembly dynamic process over the broad temperature range studied compared to the longer ones. A high frequency dielectric absorption (Process I) was observed in all samples. This is related to the dynamics of the hydrogen bond network from the sugar group. An additional low-frequency mechanism (Process II) with a large dielectric strength was observed due to the internal dynamics of the self-assembly organization. Phase sensitive domain heterogeneity in the bicontinuous cubic phase was related to the diffusion of charge carriers. The microscopic features of charge hopping were modelled using the random walk scheme, and two charge carrier hopping lengths were estimated for two glycolipid systems. For Process I, the hopping length is comparable to the hydrogen bond and is related to the dynamics of the hydrogen bond network. Additionally, that for Process II is comparable to the bilayer spacing, hence confirming that this low-frequency mechanism is associated with the internal dynamics within the phase.
Strain MUSC 115(T) was isolated from mangrove soil of the Tanjung Lumpur river in the state of Pahang, Peninsular Malaysia. Cells of this strain stained Gram-positive and were non-spore-forming, short rods that formed yellowish-white colonies on different agar media. The taxonomy of strain MUSC 115(T) was studied by a polyphasic approach, and the organism showed a range of phylogenetic and chemotaxonomic properties consistent with those of the genus Microbacterium. The cell-wall peptidoglycan was of type B2β, containing the amino acids ornithine, alanine, glycine, glutamic acid and homoserine. The muramic acid was of the N-glycolyl form. The predominant menaquinones detected were MK-12, MK-13 and MK-11. The polar lipids consisted of phosphatidylglycerol, phosphoglycolipid, diphosphatidylglycerol, two unidentified lipids, three unidentified phospholipids and four unidentified glycolipids. The major fatty acids of the cell membrane were anteiso-C15:0 and anteiso-C17:0. The whole-cell sugars detected were ribose, glucose, mannose and galactose. Based on the 16S rRNA gene sequence, strain MUSC 115(T) showed the highest sequence similarity to Microbacterium immunditiarum SK 18(T) (98.1%), M. ulmi XIL02(T) (97.8%) and M. arborescens DSM 20754(T) (97.5%) and lower sequence similarity to strains of other species of the genus Microbacterium. DNA-DNA hybridization experiments revealed a low level of DNA-DNA relatedness (less than 24%) between strain MUSC 115(T) and the type strains of closely related species. Furthermore, BOX-PCR fingerprint comparison also indicated that strain MUSC 115(T) represented a unique DNA profile. The DNA G+C content determined was 70.9 ± 0.7 mol%, which is lower than that of M. immunditiarum SK 18(T). Based on the combination of genotypic and phenotypic data, it is proposed that strain MUSC 115(T) represents a novel species of the genus Microbacterium, for which the name Microbacterium mangrovi sp. nov. is proposed. The type strain is MUSC 115(T) ( = MCCC 1K00251(T) = DSM 28240(T) = NBRC 110089(T)).
The rational design of a glycolipid application (e.g. drug delivery) with a tailored property depends on the detailed understanding of its structure and dynamics. Because of the complexity of sugar stereochemistry, we have undertaken a simulation study on the conformational dynamics of a set of synthetic glycosides with different sugar groups and chain design, namely dodecyl β-maltoside, dodecyl β-cellobioside, dodecyl β-isomaltoside and a C12C10 branched β-maltoside under anhydrous conditions. We examined the chain structure in detail, including the chain packing, gauche/trans conformations and chain tilting. In addition, we also investigated the rotational dynamics of the headgroup and alkyl chains. Monoalkylated glycosides possess a small amount of gauche conformers (∼20%) in the hydrophobic region of the lamellar crystal (LC) phase. In contrast, the branched chain glycolipid in the fluid Lα phase has a high gauche population of up to ∼40%. Rotational diffusion analysis reveals that the carbons closest to the headgroup have the highest correlation times. Furthermore, its value depends on sugar type, where the rotational dynamics of an isomaltose was found to be 11-15% and more restrained near the sugar, possibly due to the chain disorder and partial inter-digitation compared to the other monoalkylated lipids. Intriguingly, the present simulation demonstrates the chain from the branched glycolipid bilayer has the ability to enter into the hydrophilic region. This interesting feature of the anhydrous glycolipid bilayer simulation appears to arise from a combination of lipid crowding and the amphoteric nature of the sugar headgroups.
Strain MUSC 117(T) was isolated from mangrove soil of the Tanjung Lumpur forest in Pahang, Malaysia. This bacterium was yellowish-white pigmented, Gram-staining-positive, rod-coccus shaped and non-motile. On the basis of 16S rRNA gene sequence, strain MUSC 117(T) exhibited highest sequence similarity to Sinomonas atrocyanea DSM 20127(T) (98.0 %), Sinomonas albida LC13(T) (97.9 %) and Sinomonas soli CW 59(T) (97.8 %), and lower (<97.6 %) sequence similarity to other species of the genus Sinomonas. DNA-DNA hybridization experiments revealed a low level of DNA-DNA relatedness (less than 27 %) between strain MUSC 117(T) and closely related species. Chemotaxonomically, the peptidoglycan type was A3α, containing the amino acids lysine, serine, glycine, alanine, glutamic acid and muramic acid. The whole-cell sugars detected were rhamnose, ribose, glucose, galactose and a smaller amount of mannose. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and five unidentified glycolipids. The major fatty acids (>10.0 %) of the cell membrane were anteiso-C15 : 0 (39.4 %), C18 : 1ω7c (17.7 %), anteiso-C17 : 0 (17.2 %) and iso-C16 : 0 (11.4 %). The predominant respiratory quinones detected were MK-9(H2) and MK-9. The DNA G+C content was 67.3 mol%. A comparison of BOX-PCR fingerprints indicated that strain MUSC 117(T) represented a unique DNA profile. Results based on a polyphasic approach showed that strain MUSC 117(T) represents a novel species of the genus Sinomonas, for which the name Sinomonas humi sp. nov. is proposed. The type strain of Sinomonas humi sp. nov. is MUSC 117(T) ( = DSM 29362(T) = MCCC 1K00410(T) = NBRC 110653(T)).
A series of glycolipid crown ether analogs was prepared by bis-propargylation of lauryl glycoside followed by subsequent click-coupling with ethylene glycol-based diazides. The triazole-linked macrocycles were obtained in remarkable high yields. While the surfactant assembly was affected by presence of sodium ions, suggesting the formation of complexes, no ion-selectivity was observed for the macrocylic ligands. Computational studies suggest a low but significant cation-binding activity of the macrocycle, involving coordination at both oxygen and nitrogen atoms.