Accelerated Solid Phase Glycan Synthesis: ASGS

Solid phase synthesis is the most dominant approach for the preparation of biological oligomers as it enables the introduction of monomers iteratively. Accelerated solid phase synthesis of biological oligomers is crucial for chemical biology, but its application to the synthesis of oligosaccharides is not trivial. Solid-phase oligosaccharide assembly is a slow process performed in a variety of conditions and temperatures, requires an inert gas atmosphere, and demands high excess of glycosyl donors. The process is done in special synthesizers and poor mixing of the solid support increases the risk of diffusion-independent hydrolysis of the activated donors. High shear stirring is a new way to accelerate solid phase synthesis. The efficient mixing ensures that reactive intermediates can diffuse faster to the solid support thereby increasing the kinetics of the reactions. We report here a stirring-based accelerated solid-phase oligosaccharide synthesis. We harnessed high shear mixing to perform diffusion-dependent glycosylation in a short reaction time. We minimized the use of glycosyl donors and the need to use an inert atmosphere. We showed that by tailoring the deprotection and glycosylation conditions to the same temperature, assembly steps are performed continuously, and full glycosylation cycles is completed in minutes.

Translating solution to solid phase glycosylation conditions

Optimization of glycosylation conditions for automated glycan assembly is highly challenging, demands wasteful use of precious building blocks, and relies on nontrivial analyses. We developed a semi-quantitative method for automated optimization of glycosylation temperature that utilized minute quantities of donors and translated those conditions to solid-phase glycan assembly.

Automated Quantification of Hydroxyl Reactivities: Prediction of Glycosylation Reactions

The stereoselectivity and yield in glycosylation reactions are paramount but unpredictable. We have developed a database of acceptor nucleophilic constants (Aka) to quantify the nucleophilicity of hydroxyl groups in glycosylation influenced by the steric, electronic and structural effects, providing a connection between experiments and computer algorithms. The subtle reactivity differences among the hydroxyl groups on various carbohydrate molecules can be defined by Aka, which is easily accessible by a simple and convenient automation system to assure high reproducibility and accuracy. A diverse range of glycosylation donors and acceptors with well-defined reactivity and promoters were organized and processed by the designed software program "GlycoComputer" for prediction of glycosylation reactions without involving sophisticated computational processing. The importance of Aka was further verified by random forest algorithm, and the applicability was tested by the synthesis of a Lewis A skeleton to show that the stereoselectivity and yield can be accurately estimated.

[Analysis on epidemiological characteristics and related factors of dyslipidemia among adult residents of Xinjiang Uygur Autonomous Region during 2013-2014]

Objective: To study the epidemiological characteristics and related factors of dyslipidemia among adult residents in Xinjiang Uygur Autonomous Region (Xinjiang) in 2013-2014. Methods: A total of 4 120 adult residents consisting of Han and Uygur group aged over 18 years old were selected by using a stratified cluster random sampling method in 8 counties of Xinjiang from 2013 to 2014. The related factors of dyslipidemia were collected by questionnaire and physical measurement. The total cholesterol, triglyceride, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol were detected by enzyme method. Factors associated with dyslipidemia were analyzed by chi-squared test and a multivariate unconditioned logistic regression model adjusted for gender, urban or rural area, age-group, body mass index (BMI), central obesity, smoking, drinking, education attainment, diabetes mellitus and hypertension. Results: The prevalence of dyslipidemia was 45.00% (1 854 cases). The prevalence of dyslipidemia was higher in Uygur group (47.80% (977/2 044)) than that in Han group (42.24% (877/2 076)) (χ(2)=12.84, P<0.001). The analysis showed that dyslipidemia was related with gender (OR=0.41, 95%CI: 0.33-0.51), urban area (OR=0.54, 95%CI: 0.39-0.76), BMI (overweight group (OR=1.52, 95%CI: 1.18-1.96); obesity group (OR=2.20, 95%CI: 1.64-2.96)), central obesity (OR=1.66, 95%CI: 1.29-2.14) and diabetes mellitus (OR=1.49, 95%CI: 1.06-2.11) in Uygur group. The analysis also showed that dyslipidemia was related with BMI (overweight group (OR=1.72, 95%CI: 1.32-2.25), obesity group (OR=2.60, 95%CI: 1.85-3.64)), central obesity (OR=1.45, 95%CI: 1.13-1.87), smoking (OR=1.46, 95%CI: 1.09-1.95), diabetes mellitus (OR=1.77, 95%CI: 1.38-2.25) and hypertension (OR=1.62, 95%CI: 1.31-2.00) in Han group. Conclusions: The prevalence of dyslipidemia in Xinjiang was higher than the national average prevalence. The prevalence of dyslipidemia in Uygur group was significantly higher than that in Han group. The gender, living area, BMI, central obesity and diabetes mellitus were risk factors of dyslipidemia in Uygur group, and BMI, central obesity, smoking, diabetes mellitus and hypertension were risk factors of dyslipidemia in Han group in Xinjiang.

Microwave enhanced advanced oxidation treatment of dairy manure

The microwave enhanced advanced oxidation process (MW-AOP) was used to treat dairy manure in a continuous-flow 915 MHz microwave wastewater treatment system. The treatment efficiency increased with an increase in temperature, as well as hydrogen peroxide dosage. The settling property was also improved in all treated sets, regardless of temperature applied. The system operated at temperatures >100 °C had a much higher soluble chemical oxygen demand than at temperatures <100 °C. The highest soluble carbonaceous compounds, orthophosphate and ammonia were obtained at 110 °C and 0.6%H₂O₂ per % of total solids content. The process should be operated at higher temperatures and higher hydrogen peroxide dosages for maximizing solids disintegration, nutrient release and energy efficiency. An energy fingerprint correlating the cumulative energy consumption and temperature rise was developed. The results demonstrated that the custom designed MW-AOP system is suitable for the effective treatment of dairy manure. The system can readily be scaled up and integrated into a dairy farm manure treatment and resource recovery system.

"One-Pot" Protection, Glycosylation, and Protection-Glycosylation Strategies of Carbohydrates

Carbohydrates, which are ubiquitously distributed throughout the three domains of life, play significant roles in a variety of vital biological processes. Access to unique and homogeneous carbohydrate materials is important to understand their physical properties, biological functions, and disease-related features. It is difficult to isolate carbohydrates in acceptable purity and amounts from natural sources. Therefore, complex saccharides with well-defined structures are often most conviently accessed through chemical syntheses. Two major hurdles, regioselective protection and stereoselective glycosylation, are faced by carbohydrate chemists in synthesizing these highly complicated molecules. Over the past few years, there has been a radical change in tackling these problems and speeding up the synthesis of oligosaccharides. This is largely due to the development of one-pot protection, one-pot glycosylation, and one-pot protection-glycosylation protocols and streamlined approaches to orthogonally protected building blocks, including those from rare sugars, that can be used in glycan coupling. In addition, new automated strategies for oligosaccharide syntheses have been reported not only for program-controlled assembly on solid support but also by the stepwise glycosylation in solution phase. As a result, various sugar molecules with highly complex, large structures could be successfully synthesized. To summarize these recent advances, this review describes the methodologies for one-pot protection and their one-pot glycosylation into the complex glycans and the chronological developments associated with automated syntheses of oligosaccharides.

Single-fabrication-step Ge nanosphere/SiO2/SiGe heterostructures: a key enabler for realizing Ge MOS devices

We report channel and strain engineering of self-organized, gate-stacking heterostructures comprising Ge-nanosphere gate/SiO₂/SiGe-channels. An exquisitely-controlled dynamic balance between the concentrations of oxygen, Si, and Ge interstitials was effectively exploited to simultaneously create these heterostructures in a single oxidation step. Process-controlled tunability of the channel length (5-95 nm diameters for the Ge-nanospheres), gate oxide thickness (2.5-4.8 nm), as well as crystal orientation, chemical composition and strain engineering of the SiGe-channel was achieved. Single-crystalline (100) Si_1-x Ge _x shells with Ge content as high as x = 0.85 and with a compressive strain of 3%, as well as (110) Si_1-x Ge _x shells with Ge content of x = 0.35 and corresponding compressive strain of 1.5% were achieved. For each crystal orientation, our high Ge-content, highly-stressed SiGe shells feature a high degree of crystallinity and thus, provide a core 'building block' required for the fabrication of Ge-based MOS devices.

Synthesis of d-Galactosamine and d-Allosamine Derivatives via a Microwave-Assisted Preparation of 1,6-Anhydroglucosamine

We report a microwave-assisted intramolecular anomeric protection (iMAP) of glucosamine, which facilitates concise transformation of 1,6-anhydroglucosamine into 1,6-anhydrogalactosamine and 1,6-anhydroallosamine. The iMAP simultaneously obviates both the O1 and O6 protection, and the differentiation between O3 and O4 can be well-controlled by the N2 functionality because of the hydrogen bonding between N2 and O4. Epimerization of O4 afforded the galactosamine derivative and that of O3 yielded allosamine.

Effects of irradiation intensity and pH on nutrients release and solids destruction of waste activated sludge using the microwave-enhanced advanced oxidation process

Using the microwave-enhanced advanced oxidation process (MW/H2O2-AOP), the pH and irradiation intensity on waste activated sludge samples were investigated to provide insight to the athermal effects on nutrients release, solids destruction, particle size distribution and dewaterability, and to demonstrate their interrelationships. Carbonaceous matters and nutrients released into solution depended on the irradiation intensity and time. Higher irradiation levels tended to be more effective in the solubilization of nutrients and had more pronounced effects in the dewaterability of sludge. In terms of particle size distribution, detectable particles increased in size for treatments in acidic conditions, while the dewaterability of treated sludge was improved. In treatments under neutral and alkaline conditions, the particle size range increased, with more small particles formed, thereby significantly deteriorating the dewaterability of sludge treated in alkaline conditions. The best results for the solubilization of nutrients were in alkaline conditions with high irradiation power, but dewaterability of the sludge was compromised. Sludge treatment with the MW/H2O2-AOP in acidic conditions with high irradiation power yielded the best dewaterable sludge and significant nutrient solubilization; therefore, it is the recommended treatment condition for activated sludge.

Extraction of nutrients from foam in a membrane activated sludge system

This study investigated the feasibility of treating the foams generated in enhanced biological phosphorus removal processes with the microwave-enhanced advanced oxidation process to reduce solids and solubilize nutrients for recovery purposes. It was found that more than half of the total chemical oxygen demand was solubilized during the treatment with just a small dose of hydrogen peroxide, signifying effective destruction of foam solids. Significant solubilization of phosphates, volatile fatty acids and ammonia was also observed, along with the release of metals contained in the foam, including calcium, potassium, and magnesium, which thereby represents additional potential benefits for nutrient recovery via subsequent crystallization processes. Since the solids content of foam is typically high, pretreatment for thickening sludge solids is not necessary prior to the use of microwave-enhanced advanced oxidation processes. As a result, this also offers further potential for reduction of energy costs. The process could be an efficient method for the removal and control of foam and the recovery of all available phosphorus at the same time.

Disinfection and solubilization of sewage sludge using the microwave enhanced advanced oxidation process

The microwave enhanced advanced oxidation process (MW/H(2)O(2)-AOP) was used to treat municipal sewage sludge for solids disintegration, nutrient solubilization, with an emphasis on pathogen destruction and regrowth. Pathogen reduction, in terms of fecal coliform concentrations were found below detection limit (1000 CFU/L) immediately after treatment when sludge was treated at 70 degrees C with more than 0.04% of H(2)O(2) (w/w). Significant regrowth of fecal coliforms was observed for the treated samples after 72 h. However, no regrowth was observed for samples treated at 70 degrees C with 0.08% H(2)O(2) or higher, suggesting a complete elimination of fecal coliforms. The range of hydrogen peroxide used did not have a significant effect on orthophosphate release regardless of temperature. Ammonia release at these low temperatures was found to be insignificant. The soluble chemical oxygen demand increased with an increase of hydrogen peroxide dosage at 70 degrees C. However, there was no clear trend of soluble chemical oxygen demand over varying hydrogen peroxide dosage at 55 degrees C. The MW/H(2)O(2)-AOP is a novel process for the pasteurization and stabilization of sewage sludge to meet and maintain Class A biosolids criteria.

Recent progress in the development of inhibitors of human immunodeficiency virus (HIV) integrase for the management of HIV infection

Current therapy of acquired immune deficiency syndrome (AIDS) involves the use of a combination of at least three antiviral drugs to inhibit Human immunodeficiency virus 1 and 2 (HIV-1 and 2, in short HIV) replication via targeting of viral reverse transcriptase and protease. However, all anti-HIV drugs give rise to the new retroviral resistant strains. Therefore, new therapeutic agents against the emerging resistant HIV strains without secondary effects are very much needed. In HIV infection, the integration of viral DNA obtained from RNA genome into the chromosome of the host cell by viral integrase (IN) is essential for an effective viral replication. Moreover, no cellular IN has been found in the cells suggesting that viral IN appears to be one of the best candidates for the development of an antiviral drug. In recent years, promising results have proved that IN inhibitors are useful for treatment of retroviral infections. In this review, we briefly introduce IN and summarize potential inhibitors of IN, which are classified into several groups according to their origin and chemical structure. The resistance to the IN inhibitors is also discussed. Currently, several IN inhibitors are either being used in the clinical treatment or tested in clinical trials. Nevertheless, a great effort must be made to elicit wide knowledge with respect to the design of better viral inhibitors and the synthesis of new chemical derivatives with an anti-HIV activity.

Rapid determination of total Kjeldahl nitrogen using microwave digestion

A closed-vessel microwave digestion process for the determination of total Kjeldahl nitrogen (TKN) has been developed for sewage and wastewater. TKN values obtained from the microwave digestion method were in excellent agreement with those of the thermal digestion method. The accuracy of both analytical methods is comparable. In comparison to the conventional thermal digestion, the microwave method shortened the time required for complete digestion from 4 h to 25 min, and also decreased the maximum digestion temperature from 380 degrees C to 200 degrees C. This developed method may contribute to a significant reduction in sample digestion time, resulting in an increase in analytical throughput. The microwave digestion method developed in this study could be a rapid and efficient means for TKN determination for sewage wastewater and sludge.

Synergistic effect of cadmium chloride and acetaldehyde on cytotoxicity and its prevention by quercetin and glycyrrhizin

Cadmium chloride at concentrations of 10-50mM and acetaldehyde (AA) at 1-5mM showed synergistic toxic effects on V79 cells in vitro. Furthermore, synergistic effects of these chemicals were also observed in mutagenicities of the Hprt gene within certain dose ranges (cadmium chloride 5-10mM, and AA 1-2.5mM). Moreover, lipid peroxide formation, malondialdehyde (MDA) formation, detected by 2-thiobarbituric acid (TBA) reaction and the mitochondrial membrane potentials detected by rhodamine 123 uptake were significantly increased with the combined effect of cadmium and AA in V79. Thus, the cytotoxicity and genotoxicity displayed by combination of these chemicals can be considered to be associated with oxidative stress. Further, these effects were efficiently reduced by quercetin and less efficiently with glycyrrhizin.

Adenomatous polyposis coli gene mutation and decreased wild-type p53 protein expression in oral submucous fibrosis: a preliminary investigation

OBJECTIVE

The purpose of this study was to identify the adenomatous polyposis coli (APC) tumor suppressor gene mutation and level of wild-type p53 protein expression in patients with oral submucous fibrosis (OSF).

STUDY DESIGN

Cells from OSF and control subjects were cultured in Dulbecco modified Eagle medium with 10% fetal bovine serum at 37 degrees C. Genomic DNA was extracted from cultured cells and used as a template for polymerase chain reaction amplification of the APC tumor suppressor gene. The presence of wild-type p53 protein in cell lysates of cultured cells was analyzed by Western blot. Data were analyzed by the sign test for nonparametric samples and by analysis of variance.

RESULTS

The results showed that the APC gene of explant cultured cells from OSF patients (8/8) had a CGA-to-GGA transition mutation at codon 498 that resulted in an Arg-to-Gly missense mutation (P <.01). All (8/8) normal HGF cultures revealed expression of the wild-type APC protein. Cells cultured from 7 of 8 OSF patients were also found to have a single nucleotide deletion at nucleotide 1494 that resulted in creating a stop codon (TGA) at codon 504 (P <.01). This created a premature signal for the endpoint of translation and thus resulted in the generation of a truncated protein product that encodes a polypeptide of 503 amino acid residue. It was found that wild- type p53 protein in human gingival fibroblast cell cultures was significantly higher than in OSF cells (P <.01).

CONCLUSION

Alterations of the APC and wild-type p53 tumor suppressor genes in OSF may imply a risk for progression to oral cancer.

Preferential cytotoxicity of caffeic acid phenethyl ester analogues on oral cancer cells

As part of our previous search for new compounds with improved biological activities including antibiotic, antiviral, anti-inflammatory, and tumor growth inhibition activities, we synthesized some caffeic acid phenethyl ester (CAPE)-like compounds from commercially available caffeic acid. Nine chemicals were tested by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on the growth of buccal mucosal fibroblast (BF), oral submucosus fibroblast (OSF), neck metastasis of Gingiva carcinoma (GNM), and tongue squamous cell carcinoma (TSCCa) cells. CAPE and its ethyl analogue show significant cytotoxicity on OSF, GNM, and TSCCa cells, but not on BF cells. The results suggest that CAPE-like compounds may be potential chemotherapy agents against oral cancer.

Mutation of p53 gene codon 63 in saliva as a molecular marker for oral squamous cell carcinomas

The inactivation of tumor suppressor gene (TSG) is important during multistage carcinogenesis. The p53 TSG is frequently mutated in oral squamous cell carcinomas. These mutations can serve as very specific markers for the presence of tumor cells in a background of normal cells. In this study, 10 oral squamous cell carcinoma patients and 27 normal dental students were collected from Chung Shan Medical and Dental College Hospital, Taichung, Taiwan. Extractions of DNA from saliva were obtained. Exon 4 and intron 6 within the p53 gene were amplified with polymerase chain reactions (PCRs) followed by DNA sequence analysis. DNA sequence analysis of PCR products revealed that five of eight (62.5%) tumor saliva samples and five of 27 (18. 52%) healthy saliva samples contained p53 exon 4 codon 63 mutations. These results were significantly different by using Chi-square test (P<0.05). The majority of the base substitutions were C deletions. Probable hot spots for the mutation were identified at exon 4 codon 63, which has not been observed before in head and neck cancers. Our study indicated that mutation of p53 codon 63 in saliva might be a molecular marker for oral squamous cell carcinomas. In addition, the amount of DNA recovered from saliva in most cases is sufficiently large and its quality suitable to enable PCR amplification which could be used in the search for mutations. The protocol described is rapid, cheap, and easy to perform, and may be useful for epidemiological studies for oral carcinogenesis.

Mutagenesis and expression of the E3-19k lumenal domain of adenovirus type 2

CD8+ T cells recognize viral or tumor antigens of 8-10 residues derived from cytosolic proteins that are bound to the class I molecules of the major histocompatibility complex (MHC). To escape this immune surveillance, adenovirus expresses a protein, E3-19k, that specifically down-regulates the cell surface expression of class I MHC molecules on infected cells. To most effectively manipulate the T-cell response to virus-infected cells, it is essential to understand the mechanism by which viruses, such as adenoviruses, down-regulate the class I MHC function. We have subcloned the lumenal domain of adenovirus E3-19k protein in order to characterize its interactions with the class I MHC molecules. Several point mutations have also been generated on the E3-19k lumenal domain with either the first 96 or 108 amino acids. Attempts to crystallize the complexes between E3-19k and class I MHC molecule had been initiated.

Purification and crystallization of precursors and autoprocessed enzymes of Flavobacterium glycosylasparaginase: an N-terminal nucleophile hydrolase

Glycosylasparaginase (GA) represents a novel group of proteins that are activated by self-catalyzed peptide-bond cleavage from a single-chain precursor to yield the two subunits required for hydrolase activity. The wild-type GA precursor autoproteolyzes spontaneously into alpha and beta subunits. Strategies are reported here for purification to homogeneity of GA from Flavobacterium meningosepticum in both single-chain precursor and mature (autoprocessed) forms. The recombinant proteins crystallize in different space groups: P1 and P2(1) for the precursor and mature enzymes, respectively. The precursor crystals diffract to 1.9 A resolution with laboratory X-ray radiation.

Reduction of ornithine decarboxylase antizyme (ODC-Az) level in the 7,12-dimethylbenz(a)anthracene-induced hamster buccal pouch carcinogenesis model

Ornithine decarboxylase (ODC) activity is elevated in and necessary for oral carcinogenesis, but the mechanism for its deregulation is unclear. Using subtractive hybridization, a 1029 bp full-length cDNA encoding a 222 amino acid open reading frame has been isolated from normal hamster oral keratinocytes. The hamster cDNA is homologous to the human, mouse and rat ornithine decarboxylase antizyme gene (ODC-Az). The hamster ODC-Az gene demonstrated a restriction fragment length polymorphism (RFLP) upon Southern blot analysis comparing normal and tumor hamster genomic DNA. Northern blot analysis revealed that normal hamster oral keratinocytes express readily detectable level of ODC-Az mRNA. Malignant oral keratinocytes demonstrate reduced expression of the ODC-Az mRNA. In contrast, malignant hamster oral keratinocytes have elevated ODC mRNA levels and lengthened ODC protein half-life when compared to the normal counterparts. This was corroborated by direct measurement of ODC enzymatic activity. These data support the hypothesis that the reduced and/or loss of expression and function of the ODC-Az gene is an important event for the early de-regulation of cellular proliferation during oral tumor development.