Conversion of L-arabinose to L-ribose by genetically engineered Candida tropicalis.

L-Ribose, a starting material for the synthesis of L-nucleoside, has attracted lots of attention since L-nucleoside is responsible for the antiviral activities of the racemic mixtures of nucleoside enantiomers. In this study, the L-ribulose-producing Candida tropicalis strain was engineered for the conversion of L-arabinose to L-ribose. For the construction of a uracil auxotroph, the URA3 gene was excised by homologous recombination.

Antimicrobial Activity of Amino-Derivatized Cationic Polysaccharides.

To improve the antimicrobial property of chitosan, water-soluble chitosan modified in their quaternary ammonium groups were synthesized. The antimicrobial properties were evaluated against , , and The activities increased with increasing cationic charges and the length of the alkyl chain as follows amino-chitosan, dimethylaminoethyl-chitosan, dimethylpropyl amino-chitosan, dimethylamino-1-propyl-chitosan, diethylaminoethyl (DEAE)-chitosan, and quaternized DEAE-chitosan. The modified cationic chitosans showed high antimicrobial property against -Gram-positive bacteria, but were less active towards yeast ( and and -Gram-negative bacteria.

Inhibition of poly-LacNAc biosynthesis with release of CMP-Neu5Ac feedback inhibition increases the sialylation of recombinant EPO produced in CHO cells.

Sialylation of recombinant therapeutic glycoproteins modulates their pharmacokinetic properties by affecting their in vivo half-life. N-glycan branching on glycoproteins increases the number of potential attachment sites for sialic acid. Here, we introduce a new approach for increasing the sialylation of recombinant human erythropoietin (rhEPO) produced in CHO cells by modulating poly-N-acetyllactosamine (poly-LacNAc) biosynthesis.

Construction of genetically engineered Candida tropicalis for conversion of l-arabinose to l-ribulose.

For the biological production of l-ribulose, conversion by enzymes or resting cells has been investigated. However, expensive or concentrated substrates, an additional purification step to remove borate and the requirement for cell cultivation and harvest steps before utilization of resting cells make the production process complex and unfavorable. Microbial fermentation may help overcome these limitations.

Designation of fingerprint glycopeptides for targeted glycoproteomic analysis of serum haptoglobin: insights into gastric cancer biomarker discovery.

Gastric cancer (GC) is one of the leading causes of cancer-related death worldwide, largely because of difficulties in early diagnosis. Despite accumulating evidence indicating that aberrant glycosylation is associated with GC, site-specific localization of the glycosylation to increase specificity and sensitivity for clinical use is still an analytical challenge. Here, we created an analytical platform with a targeted glycoproteomic approach for GC biomarker discovery.

Enhancing the sialylation of recombinant EPO produced in CHO cells via the inhibition of glycosphingolipid biosynthesis.

Sialylation regulates the in vivo half-life of recombinant therapeutic glycoproteins, affecting their therapeutic efficacy. Levels of the precursor molecule cytidine monophospho-N-acetylneuraminic acid (CMP-Neu5Ac) are considered a limiting factor in the sialylation of glycoproteins. Here, we show that by reducing the amount of intracellular CMP-Neu5Ac consumed for glycosphingolipid (GSL) biosynthesis, we can increase the sialylation of recombinant human erythropoietin (rhEPO) produced in CHO cells.

Direct analysis of aberrant glycosylation on haptoglobin in patients with gastric cancer.

Based on our previous studies, differential analysis of N-glycan expression bound on serum haptoglobin reveals the quantitative variation on gastric cancer patients. In this prospective case-control study, we explore the clinically relevant glycan markers for gastric cancer diagnosis. Serum samples were collected from patients with gastric cancer (n = 44) and healthy control (n = 44).

Glycomic profiling of targeted serum haptoglobin for gastric cancer using nano LC/MS and LC/MS/MS.

Gastric cancer has one of the highest cancer mortality rates worldwide, largely because of difficulties in early-stage detection. Aberrant glycosylation in serum proteins is associated with many human diseases including inflammation and various types of cancer. Serum-based global glycan profiling using mass spectrometry has been explored and has already led to several potential glycan markers for several disease states.

Metabolic engineering of Pichia pastoris for production of hyaluronic acid with high molecular weight.

The high molecular weight (>1 MDa) of hyaluronic acid (HA) is important for its biological functions. The reported limiting factors for the production of HA with high molecular weight (MW) by microbial fermentation are the insufficient HA precursor pool and cell growth inhibition. To overcome these issues, the Xenopus laevis xhasA2 and xhasB genes encoding hyaluronan synthase 2 (xhasA2) and UDP-glucose dehydrogenase (xhasB), were expressed in Pichia pastoris widely used for production of heterologous proteins.

Effect of mild-thiol reducing agents and alpha2,3-sialyltransferase expression on secretion and sialylation of recombinant EPO in CHO cells.

We have previously reported that N-acetylcysteine (NAC) not only delayed apoptosis but also enhanced the production of recombinant erythropoietin (EPO) in Chinese hamster ovary (CHO) cell culture. To investigate the production enhancement mechanism, the effects of similar thiolreducing agents were studied. Intriguingly, all mild reducing agents examined including mercaptoethanesulfonic acid (MESNA), thiolactic acid (TLA), and thioglycolate (TG) were shown to block apoptosis and increase EPO production.

Effect of heterologous xylose transporter expression in Candida tropicalis on xylitol production rate.

Xylose utilization is inhibited by glucose uptake in xylose-assimilating yeasts, including Candida tropicalis, resulting in limitation of xylose uptake during the fermentation of glucose/xylose mixtures. In this study, a heterologous xylose transporter gene (At5g17010) from Arabidopsis thaliana was selected because of its high affinity for xylose and was codon-optimized for functional expression in C. tropicalis.

Enhancement of xylitol production in glycerol kinase disrupted Candida tropicalis by co-expression of three genes involved in glycerol metabolic pathway.

Glycerol can be used as a primary carbon source by yeasts, little is known regarding glycerol metabolism in Candida tropicalis. In this study, glycerol kinase gene (gk) was disrupted from xylitol dehydrogenase gene (XYL2) knockout C. tropicalis strain BSXDH-3.

Factors associated with medical cost among patients with terminal cancer in hospice units.

This study identified factors associated with higher medical costs for patients with terminal cancer in hospice units in order to develop a daily payment system for hospice services within Korea's National Health Insurance (NHI) program. Through chart reviews conducted by staff nurses, medical information and costs were obtained for 274 patients with terminal cancer in 20 hospice units in October 2007. The daily medical cost per patient was calculated based on the fee-for-service scheme.

Variations in pain management outcomes among palliative care centers and the impact of organizational factors.

Background: The assessment of pain management outcomes is important for the quality assurance of palliative care. The objective of this study was to determine whether there are significant variations in pain management outcomes among palliative care centers and whether they are affected by organizational factors.

Methods: Data used in this investigation were from the 2009 Korean Terminal Cancer Patient Information System and administrative records of the 34 inpatient palliative care centers designated by the Korean Ministry of Health and Welfare in 2009.

Globoside promotes activation of ERK by interaction with the epidermal growth factor receptor.

Background: Globoside (Gb4), a globo-series glycosphingolipid (GSL), has been characterized as a stage-specific embryonic antigen (SSEA), and is highly expressed during embryogenesis as well as in cancer tissues. However, the functional role and molecular mechanism of Gb4 are so far unknown.

Methods: GSLs were preferentially inhibited by treatment with D-threo-1-ethylenedioxyphenyl-2-palmitoylamino-3-pyrrolidino-1-propanol (EtDO-P4), a nanomolar inhibitor of GSL synthesis, in two carcinoma cell lines, HCT116 and MCF7.

Enhancement of xylitol production in Candida tropicalis by co-expression of two genes involved in pentose phosphate pathway.

The yeast Candida tropicalis produces xylitol, a natural, low-calorie sweetener whose metabolism does not require insulin, by catalytic activity of NADPH-dependent xylose reductase. The oxidative pentose phosphate pathway (PPP) is a major basis for NADPH biosynthesis in C. tropicalis.

Xylitol production is increased by expression of codon-optimized Neurospora crassa xylose reductase gene in Candida tropicalis.

Xylose reductase (XR) is the first enzyme in D: -xylose metabolism, catalyzing the reduction of D: -xylose to xylitol. Formation of XR in the yeast Candida tropicalis is significantly repressed in cells grown on medium that contains glucose as carbon and energy source, because of the repressive effect of glucose. This is one reason why glucose is not a suitable co-substrate for cell growth in industrial xylitol production.

α1-3/4 fucosylation at Asn 241 of β-haptoglobin is a novel marker for colon cancer: a combinatorial approach for development of glycan biomarkers.

Aberrant glycosylation has been observed in many types of cancer, but the mechanism of glycosylation change is still poorly understood. To elucidate relationships between glycosylation and colon cancer progression, we analyzed glycosylation status of β-haptoglobin (β-Hp) obtained from 46 cancer patients, 14 inflammatory bowel disease patients and 38 normal subjects. Aleuria aurantia lectin reactivity with cancer β-Hp was much higher than in the other two study groups.

Willingness to pay for hospice care using the contingent valuation method.

Purpose: It is necessary to develop a proper payment system for more health care facilities to provide hospice and palliative cares. In deciding the proper level of payment for hospice per diem fee, willingness to pay (WTP) may provide one of the critical information. This study was conducted to determine WTP for hospice care and to analyze those factors affecting WTP.

What is the best practical survey method for the comparative assessment of palliative care services: results from a national quality assessment project in Korea.

Context: There is an increasing need for the comparative assessment of palliative care services; however, few systematic empirical studies have been performed to determine the most feasible, representative, efficient survey method.

Objectives: To investigate the feasibility, representativeness, and efficiency of several survey methods.

Methods: This study was performed as a part of a national initiative to develop a system to evaluate the quality of palliative care services.

Enhanced sialylation of recombinant human erythropoietin in Chinese hamster ovary cells by combinatorial engineering of selected genes.

Therapeutic glycoproteins with exposed galactose (Gal) residues are cleared rapidly from the bloodstream by asialoglycoprotein receptors in hepatocytes. Various approaches have been used to increase the content of sialic acid, which occupies terminal sites of N- or O-linked glycans and thereby increases the half-life of therapeutic glycoproteins. We enhanced sialylation of human erythropoietin (EPO) by genetic engineering of the sialylation pathway in Chinese hamster ovary (CHO) cells.

Variations in process and outcome in inpatient palliative care services in Korea.

Purposes: Hospice programs in Korea have been largely based on volunteer activity, religious services, or social services. Recent government policy of designating medically based inpatient palliative care services and per diem payment system made it necessary to monitor the quality of these services. We examined the variation in the process and outcomes of palliative care services, using 2009 data obtained from the Korean Terminal Cancer Patient Information System.

Enhancement of xylitol production by attenuation of intracellular xylitol dehydrogenase activity in Candida tropicalis.

To construct Candida tropicalis strains that produce a high yield of xylitol with no requirement for co-substrates, we engineered the yeast with an attenuated xylitol dehydrogenase (XDH) and then assessed the efficiency of xylitol production The mutants, strains XDH-5 (with only one copy of the XDH gene), and ARSdR-16 (with a mutated XDH gene) showed 70 and 40% of wild type (WT) XDH activity, respectively. Conversions of xylose to xylitol by WT, XDH-5, and ARSdR-16 were 62, 64, and 75%, respectively, with productivities of 0.52, 0.

L-arabinose pathway engineering for arabitol-free xylitol production in Candida tropicalis.

Xylose reductase (XR) is a key enzyme in biological xylitol production, and most XRs have broad substrate specificities. During xylitol production from biomass hydrolysate, non-specific XRs can reduce L-arabinose, which is the second-most abundant hemicellulosic sugar, to the undesirable byproduct arabitol, which interferes with xylitol crystallization in downstream processing. To minimize the flux from L-arabinose to arabitol, the L-arabinose-preferring, endogenous XR was replaced by a D-xylose-preferring heterologous XR in Candida tropicalis.