Sequential process optimization for a digital light processing system to minimize trial and error

In additive manufacturing, logical and efficient workflow optimization enables successful production and reduces cost and time. These attempts are essential for preventing fabrication problems from various causes. However, quantitative analysis and integrated management studies of fabrication issues using a digital light processing (DLP) system are insufficient. Therefore, an efficient optimization method is required to apply several materials and extend the application of the DLP system. This study proposes a sequential process optimization (SPO) to manage the initial adhesion, recoating, and exposure energy. The photopolymerization characteristics and viscosity of the photocurable resin were quantitatively analyzed through process conditions such as build plate speed, layer thickness, and exposure time. The ability of the proposed SPO was confirmed by fabricating an evaluation model using a biocompatible resin. Furthermore, the biocompatibility of the developed resin was verified through experiments. The existing DLP process requires several trials and errors in process optimization. Therefore, the fabrication results are different depending on the operator’s know-how. The use of the proposed SPO enables a systematic approach for optimizing the process conditions of a DLP system. As a result, the DLP system is expected to be more utilized.

Modified Industrial Three-Dimensional Polylactic Acid Scaffold Cell Chip Promotes the Proliferation and Differentiation of Human Neural Stem Cells

In this study, we fabricated a three-dimensional (3D) scaffold using industrial polylactic acid (PLA), which promoted the proliferation and differentiation of human neural stem cells. An industrial PLA 3D scaffold (IPTS) cell chip with a square-shaped pattern was fabricated via computer-aided design and printed using a fused deposition modeling technique. To improve cell adhesion and cell differentiation, we coated the IPTS cell chip with gold nanoparticles (Au-NPs), nerve growth factor (NGF) protein, an NGF peptide fragment, and sonic hedgehog (SHH) protein. The proliferation of F3.Olig2 neural stem cells was increased in the IPTS cell chips coated with Au-NPs and NGF peptide fragments when compared with that of the cells cultured on non-coated IPTS cell chips. Cells cultured on the IPTS-SHH cell chip also showed high expression of motor neuron cell-specific markers, such as HB9 and TUJ-1. Therefore, we suggest that the newly engineered industrial PLA scaffold is an innovative tool for cell proliferation and motor neuron differentiation.

Immunomodulatory and anti-inflammatory efficacy of hederagenin-coated maghemite (γ-Fe2O3) nanoparticles in an atopic dermatitis model

We investigated the immunomodulatory and anti-inflammatory efficacy of hederagenin coating on maghemite (γ-Fe₂O₃) nanoparticles (HM) in atopic dermatitis (AD), as well as the physical and optical properties of maghemite nanoparticles (MP) using SEM, XRD spectroscopy, UV-vis spectra, Raman spectra, and FTIR spectroscopy. Dose-dependent treatment with HM (10, 50, 100, 200 μg/mL) inhibited the expression of Interleukin-2 (IL-2) and Tumor necrosis factor- α (TNF-α) in inflammatory induced HaCaT and Jurkat cells with inflammation caused by TNF/IFN-γ and PMA/A23187. AD model was induced by performing topical application of 2,4-dinitrochlorobenzene (DNCB) and dermatophagoides farinae extract (DFE) for a 31-day period on 8-week-old BALB/c mice. The HM treatments efficiently diminished the AD-like cutaneous lesion induced by DNCB-DFE sensitization in mice. Compared to the AD-only groups, HM treatment considerably attenuated mast cell infiltration and lowered epidermal, and dermal thickness of mice ears skin. In addition, HM treatment prominently alleviated the enlarged size and weight of lymph nodes. Furthermore, HM treatment resulted in a notable reduction in the mRNA expression of Th1 cytokines (TNF-α and IFN-γ), Th2 cytokines (IL-4 and IL-6), Th17 (IL-17), and TSLP. Our data showed that HM provides better AD attenuation compared to MP. Additionally, HM had synergistic effect and act as anti-inflammatory and immunomodulatory agent. Thus, HM shows great potential in AD medication and as a substitution of non-steroid-based medication.

Drug Evaluation Based on a Multi-Channel Cell Chip with a Horizontal Co-Culture

We developed a multi-channel cell chip containing a three-dimensional (3D) scaffold for horizontal co-culture and drug toxicity screening in multi-organ culture (human glioblastoma, cervical cancer, normal liver cells, and normal lung cells). The polydimethylsiloxane (PDMS) multi-channel cell chip (PMCCC) was based on fused deposition modeling (FDM) technology. The architecture of the PMCCC was an open-type cell chip and did not require a pump or syringe. We investigated cell proliferation and cytotoxicity by conducting 3-(4,5-dimethylthiazol-2-yl)-2,5-dphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays and analysis of oleanolic acid (OA)-treated multi-channel cell chips. The results of the MTT and LDH assays showed that OA treatment in the multi-channel cell chip of four cell lines enhanced chemoresistance of cells compared with that in the 2D culture. Furthermore, we demonstrated the feasibility of the application of our multi-channel cell chip in various analysis methods through Annexin V-fluorescein isothiocyanate/propidium iodide staining, which is not used for conventional cell chips. Taken together, the results demonstrated that the PMCCC may be used as a new 3D platform because it enables simultaneous drug screening in multiple cells by single point injection and allows analysis of various biological processes.

Fe2+: Fe3+ Molar Ratio Influences the Immunomodulatory Properties of Maghemite (γ-Fe2O3) Nanoparticles in an Atopic Dermatitis Model

Here, we report the different antioxidant and physiological effects of maghemite nanoparticles (γ-Fe2O3 NPs) obtained using various Fe2+: Fe3+ molar ratios (FM1 = 1: 1, FM2 = 1: 2, and FM3 = 2: 3) via coprecipitation from ferrous/ferric salts. We investigated the physical, optical, and antioxidant properties of FM1, FM2, and FM3 nanoparticles by conducting UV, Raman, FTIR, and EDX spectroscopic analyses along with DPPH radical scavenging activity. Results showed the highest DPPH scavenging activity in the FM2 group (50.76%), while the activity in the FM1 and FM3 groups was 23.60% and 34.63%, respectively. In addition, topical application of nanoparticles induced significant but different anti-inflammatory and immunomodulatory effects in Dermatophagoides farinae extract/2,4-dinitrochlorobenzene (DFE/DNCB)-sensitized BALB/c mice. The FM2 treatment alleviates more effectively the DFE/DNCB-induced atopic dermatitis-like (AD-like) symptoms in mouse ears (edema, excoriation, scaling, and hemorrhage). In comparison with the DFE/DNCB-sensitized mice, FM2 treatment greatly reduced the size and weight of the spleen and the lymph nodes. It also suppressed mast cell infiltration (2-fold) and reduced dermal and epidermal thickness in mice. In addition, FM2 treatment exhibited better inhibition of the mRNA levels of Th1 (IFN-γ and TNF-α) and Th2 cytokines (IL-4, IL-5, IL-6, IL-10, IL-13, and IL-31), as well as the levels of various inflammation-related proteins (COX-2, iNOS, and TNF-α). Moreover, we demonstrated that an increasing proportion of Fe3+ in Fe2+: Fe3+ enhances the antioxidant activity and increases the anti-inflammatory and immunomodulatory effects of γ-Fe2O3 NPs in an AD mouse model. Thus, γ-Fe2O3 NPs could be used in the formulation of nonsteroidal drugs for AD treatment.

Surface-Modified Industrial Acrylonitrile Butadiene Styrene 3D Scaffold Fabrication by Gold Nanoparticle for Drug Screening

Biocompatibility is very important for cell growth using 3D printers, but biocompatibility materials are very expensive. In this study, we investigated the possibility of cell culture by the surface modification of relatively low-cost industrial materials and an efficient three-dimensional (3D) scaffold made with an industrial ABS filament for cell proliferation, spheroid formation, and drug screening applications. We evaluated the adequate structure among two-layer square shape 3D scaffolds printed by fused deposition modeling with variable infill densities (10–50%). Based on the effects of these scaffolds on cell proliferation and spheroid formation, we conducted experiments using the industrial ABS 3D scaffold (IA3D) with 40% of infill density, which presented an external dimension of (XYZ) 7650 µm × 7647 µm × 210 µm, 29.8% porosity, and 225 homogenous micropores (251.6 µm × 245.9 µm × 210 µm). In the IA3D, spheroids of cancer HepG2 cells and keratinocytes HaCaT cells appeared after 2 and 3 days of culture, respectively, whereas no spheroids were formed in 2D culture. A gold nanoparticle-coated industrial ABS 3D scaffold (GIA3D) exhibited enhanced biocompatible properties including increased spheroid formation by HepG2 cells compared to IA3D (1.3-fold) and 2D (38-fold) cultures. Furthermore, the cancer cells exhibited increased resistance to drug treatments in GIA3D, with cell viabilities of 122.9% in industrial GIA3D, 40.2% in IA3D, and 55.2% in 2D cultures when treated with 100 µM of mitoxantrone. Our results show that the newly engineered IA3D is an innovative 3D scaffold with upgraded properties for cell proliferation, spheroid formation, and drug-screening applications.

Effect of Nano-Montmorillonite on Osteoblast Differentiation, Mineral Density, and Osteoclast Differentiation in Bone Formation

Calcium-type montmorillonite, a phyllosilicate mineral, has diverse health benefits when introduced into the gastrointestinal tract or applied to the skin. However, the predominant use of this layered material has thus far been in traditional industries, despite its potential application in the pharmaceutical industry. We investigated the effects and mechanism of nano-montmorillonite (NM) on osteoblast and osteoclast differentiation in vivo and in vitro. We examined the osteogenic effects of NM with high calcium content (3.66 wt%) on alkaline phosphatase (ALP) activity, mineralization, bone microarchitecture, and expression level of osteoblast and osteoclast related genes in Ca-deficient ovariectomized (OVX) rats. Micro-computed tomography of OVX rats revealed that NM attenuated the low-Ca-associated changes in trabecular and cortical bone mineral density. It improved ALP activity and mineralization, as well as the expression of osteoblast and osteoclast differentiation associated genes. NM also activated the expression of runt-related transcription factor 2, osteocalcin, bone morphogenetic protein 2, and type 1 collagen via phosphorylated small mothers against decapentaplegic homolog 1/5/8 signaling. Further, NM repressed the expression of receptor activator for cathepsin K, nuclear factor kappa-B ligand and tartrate-resistant acid phosphatase. Therefore, NM inhibits osteoclastogenesis, stimulates osteoblastogenesis, and alleviates osteoporosis.

Mitigation Effects of a Novel Herbal Medicine, Hepad, on Neuroinflammation, Neuroapoptosis, and Neuro-Oxidation

Parkinson’s disease (PD), a common adult-onset neurodegenerative disorder with complex pathological mechanisms, is characterized by the degeneration of dopaminergic nigrostriatal neurons. The present study demonstrated that the herbal medicines Hepad 1 and 2 protected against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced dopaminergic neurotoxicity in C57BL/6 mice and SH-SY5Y cells. Hepad 1 and 2 remarkably alleviated the enhanced expression of pro-inflammatory cytokines (tumor necrosis factor-α, interleukin-6, inducible nitric oxide synthase, cyclooxygenase-2, macrophage-1, and phosphorylated iκB-α) and apoptotic signals (Bcl-2-associated X protein, caspase-3, and poly [ADP-ribose] polymerase-1). Additionally, Hepad reduced MPTP-induced oxidative damage by increasing the expression of anti-oxidant defense enzymes (superoxide dismutase and glutathione S-transferase) and downregulating the levels of nicotinamide adenine dinucleotide phosphate oxidase 4. This study also showed that the neuroprotective effects of Hepad include anti-inflammatory, anti-apoptotic, and anti-oxidative properties, in addition to activation of the protein kinase B, extracellular-signal-regulated kinase, and c-Jun N-terminal kinase signaling pathways. Furthermore, oral administration of Hepad 1 and 2 attenuated the death of tyrosine hydroxylase-positive substantia nigra neurons that was induced by 20 mg/kg MPTP. Therefore, our results suggest that Hepad 1 and 2 are useful for treating PD and other disorders associated with neuro-inflammatory, neuro-apoptotic, and neuro-oxidative damage.

Image of the Micro-Computed Tomography and Atomic-Force Microscopy of Bone in Osteoporosis Animal Model

Osteoporosis, a major public health problem, is characterised by a reduction in and deterioration of bone tissue microarchitecture, with a consequent increase in bone frailty and susceptibility to fractures. We performed ex vivo micro-computed tomography (micro-CT) and atomic-force microscopy (AFM) between normal and surgically ovariectomized animals (OVX). The tibial architecture was investigated using maximum intensity projection images. Micro-CT analysis of the tibia metaphysis was used to calculate the trabecular spacing (Tb.Sp). Following OVX surgery, the rats exhibited increased Tb.Sp. Between the bundles, there are holes in the fabric with a diameter in the range of 3 to 5 μm in normal tibia. The diameter of hole in the osteoporosis tibia is the range of 5 to 10 μm, and its area increased than normal tibia. AFM can be used for the inspection of bone surfaces and offers the possibility of quantification of local geometries, such as pit size, collagen fibril diameters, or collagen ultrastructure. Our results suggest that AFM will surely become one of the most important tools in the realm of medical research for imaging such as bone and tissues.

Oleanolic acid induces p53-dependent apoptosis via the ERK/JNK/AKT pathway in cancer cell lines in prostatic cancer xenografts in mice

We evaluated oleanolic acid (OA)-induced anti-cancer activity, apoptotic mechanism, cell cycle status, and MAPK kinase signaling in DU145 (prostate cancer), MCF-7 (breast cancer), U87 (human glioblastoma), normal murine liver cell (BNL CL.2) and human foreskin fibroblast cell lines (Hs 68). The IC50 values for OA-induced cytotoxicity were 112.57 in DU145, 132.29 in MCF-7, and 163.60 in U87 cells, respectively. OA did not exhibit toxicity in BNL CL. 2 and Hs 68 cell lines in our experiments. OA, at 100 µg/mL, increased the number of apoptotic cells to 27.0% in DU145, 27.0% in MCF-7, and 15.7% in U87, when compared to control cells. This enhanced apoptosis was due to increases in p53, cytochrome c, Bax, PARP-1 and caspase-3 expression in DU145, MCF-7 and U87 cell lines. OA-treated DU145 cells were arrested in G2 because of the activation of p-AKT, p-JNK, p21 and p27, and the decrease in p-ERK, cyclin B1 and CDK2 expression; OA-treated MCF-7 cells were arrested in G1 owing to the activation of p-JNK, p-ERK, p21, and p27, and the decrease in p-AKT, cyclin D1, CDK4, cyclin E, and CDK2; and OA-treated U87 cells also exhibited G1 phase arrest caused by the increase in p-ERK, p-JNK, p-AKT, p21, and p27, and the decrease in cyclin D1, CDK4, cyclin E and CDK2. Thus, OA arrested the cell cycle at different phases and induced apoptosis in cancer cells. These results suggested that OA possibly altered the expression of the cell cycle regulatory proteins differently in varying types of cancer.

3D Hierarchical, Pyramid-Based Cancer Cell Chip for the Detection of Anticancer Drug Effects

In this study, we developed a novel three-dimensional (3D) cancer cell chip using a three-floor hierarchical 3D pyramid structure (3D pyramid) to simulate 3D tumor cell growth in vitro and to detect anticancer drugs. The proposed 3D pyramidbased cancer cell chip offered substantial advantages for the agglomerate formation of tumor cells, in which cells could be maintained as tumor spheroids for up to 3 weeks. Soon after HeLa tumor cells adhered to the micropatterned pillar sidewalls, they were suspended between the pillars based on scanning electron microscopy images. Treatment with the anticancer drug oleanolic acid resulted in 46.33% and 5.86% apoptotic cells on the 2D plate and 3D pyramid-based cell chip, respectively, compared with only 0.06% apoptotic cells in the control. The increase in chemoresistance to anticancer drugs in the 3D pyramid-based cell chip might be a result of cell confluence and hypoxia due to the spheroid formation of tumor cells in the 3D pyramid structure. These results indicated that the proposed cell chip could potentially be used for anticancer drug screening or can be incorporated into other models aimed at prolonging various cell functions in culture.

Paternal age as an independent factor does not affect embryo quality and pregnancy outcomes of testicular sperm extraction-intracytoplasmic sperm injection in azoospermia

This study was performed to evaluate the independent influence of paternal age affecting embryo development and pregnancy using testicular sperm extraction (TESE)-intracytoplasmic sperm injection (ICSI) in obstructive azoospermia (OA) and nonobstructive azoospermia (NOA). Paternal patients were divided into the following groups: ≤30 years, 31-35 years, 36-40 years, 41-45 years and ≥46 years. There were no differences in the rates of fertilisation or embryo quality according to paternal and maternal age. However, clinical pregnancy and implantation rates were significantly lower between those ≥46 years of paternal age compared with other age groups. Fertilisation rate was higher in the OA than the NOA, while embryo quality, pregnancy and delivery results were similar. Clinical pregnancy and implantation rates were significantly lower for patients ≥46 years of paternal age compared with younger age groups. In conclusion, fertilisation using TESE in azoospermia was not affected by the independent influence of paternal age; however, as maternal age increased concomitantly with paternal age, rates of pregnancy and delivery differed between those with paternal age <41 years and ≥46 years. Therefore, paternal age ≥46 years old should be considered when applying TESE-ICSI in cases of azoospermia, and patients should be advised of the associated low pregnancy rates.

Endpoints for screening thyroid cancer in the Republic of Korea: thyroid specialists' perspectives

Cancer screening is aimed primarily at reducing deaths from the specific cancer. Thyroid-specific cancer mortality may be the most ambitious endpoint for obtaining estimates of screening effect. Numerous observations have accumulated over the years, indicating that thyroid cancer mortality endpoint has been difficult to study and is confounded by population heterogeneity, provision of randomization, and requirement of large cohorts with sufficiently long follow-up due to the excellent prognosis of the cancer. Accordingly, it may be important to reconsider how to best measure thyroid cancer screening efficacy. Recommendations against thyroid cancer screening should be based upon trials designed to evaluate its effectiveness not only in significant reduction in cancer mortality, but also of other distinct endpoints. It is desirable to evaluate derivative endpoints that can reliably predict reductions in mortality. The term "derivative" means a variable that is related to the true endpoint and is likely to be observable before the primary endpoint. Derivative endpoints may include thyroid cancer incidence, the proportion of early-stage tumors detected, more treatable stage, the identification of small tumors (to maintain in observation), decrease in the number of people who develop metastatic disease, the increased chance of lesser extent surgery, and the application of minimally invasive approaches, as well as no need for lifelong thyroid replacement therapy, a consistent follow-up, low-dose or no RAI administration and risk factor assessments where case findings should be continuous. The Korean guidelines for thyroid cancer national-level screening were published by a relevant group of multidisciplinary thyroid experts. It was concluded that the evidence is insufficient to balance the benefits and harms of thyroid cancer screening. However, the paper seems to raise the necessary investments in future research and demand a complete analysis for derivative endpoints, and offer screening participants with complete information necessary to make decisions that will provide them with the most value when a small thyroid cancer is screen-identified.

Calcium Supplement Derived from Gallus gallus domesticus Promotes BMP-2/RUNX2/SMAD5 and Suppresses TRAP/RANK Expression through MAPK Signaling Activation

The present study evaluated the effects of a calcium (Ca) supplement derived from Gallus gallus domesticus (GD) on breaking force, microarchitecture, osteogenic differentiation and osteoclast differentiation factor expression in vivo in Ca-deficient ovariectomized (OVX) rats. One percent of Ca supplement significantly improved Ca content and bone strength of the tibia. In micro-computed tomography analysis, 1% Ca supplement attenuated OVX- and low Ca-associated changes in bone mineral density, trabecular thickness, spacing and number. Moreover, 1% Ca-supplemented diet increased the expression of osteoblast differentiation marker genes, such as bone morphogenetic protein-2, Wnt3a, small mothers against decapentaplegic 1/5/8, runt-related transcription factor 2, osteocalcin and collagenase-1, while it decreased the expression of osteoclast differentiation genes, such as thrombospondin-related anonymous protein, cathepsin K and receptor activator of nuclear factor kappa B. Furthermore, 1% Ca-supplemented diet increased the levels of phosphorylated extracellular signal-regulated kinase and c-Jun N-terminal kinase. The increased expression of osteoblast differentiation marker genes and activation of mitogen-activated protein kinase signaling were associated with significant increases in trabecular bone volume, which plays an important role in the overall skeletal strength. Our results demonstrated that 1% Ca supplement inhibited osteoclastogenesis, stimulated osteoblastogenesis and restored bone loss in OVX rats.

Melanin extract from Gallus gallus domesticus promotes proliferation and differentiation of osteoblastic MG-63 cells via bone morphogenetic protein-2 signaling

BACKGROUND/OBJECTIVES

Gallus gallus domesticus (GD) is a natural mutant breed of chicken in Korea with an atypical characterization of melanin in its tissue. This study investigated the effects of melanin extracts of GD on osteoblast differentiation and inhibition of osteoclast formation.

MATERIALS/METHODS

The effects of the melanin extract of GD on human osteoblast MG-63 cell differentiation were examined by evaluating cell viability, osteoblast differentiation, and expression of osteoblast-specific transcription factors such as bone morphogenetic protein 2 (BMP-2), small mothers against decapentaplegic homologs 5 (SMAD5), runt-related transcription factor 2 (RUNX2), osteocalcin and type 1 collagen (COL-1) by reverse transcription-polymerase chain reaction and western blotting analysis. We investigated the inhibitory effect of melanin on the osteoclasts formation through tartrate-resistant acid phosphatase (TRAP) activity and TRAP stains in Raw 264.7 cell.

RESULTS

The melanin extract of GD was not cytotoxic to MG-63 cells at concentrations of 50-250 µg/mL. Alkaline phosphatase (ALP) activity and bone mineralization of melanin extract-treated cells increased in a dose-dependent manner from 50 to 250 µg/mL and were 149% and 129% at 250 µg/mL concentration, respectively (P < 0.05). The levels of BMP-2, osteocalcin, and COL-1 gene expression were significantly upregulated by 1.72-, 4.44-, and 2.12-fold in melanin-treated cells than in the control cells (P < 0.05). The levels of RUNX2 and SMAD5 proteins were higher in melanin-treated cells than in control vehicle-treated cells. The melanin extract attenuated the formation of receptor activator of nuclear factor kappa-B ligand-induced TRAP-positive multinucleated RAW 264.7 cells by 22%, and was 77% cytotoxic to RAW 264.7 macrophages at a concentration of 500 µg/mL.

CONCLUSIONS

This study provides evidence that the melanin extract promoted osteoblast differentiation by activating BMP/SMADs/RUNX2 signaling and regulating transcription of osteogenic genes such as ALP, type I collagen, and osteocalcin. These results suggest that the effective osteoblastic differentiation induced by melanin extract from GD makes it potentially useful in maintaining bone health.

Hederagenin Supplementation Alleviates the Pro-Inflammatory and Apoptotic Response to Alcohol in Rats

In this study, we determined the effects of hederagenin isolated from Akebia quinata fruit on alcohol-induced hepatotoxicity in rats. Specifically, we investigated the hepatoprotective, anti-inflammatory, and anti-apoptotic effects of hederagenin, as well as the role of AKT and mitogen-activated protein kinase (MAPK) signaling pathways in ethanol-induced liver injury. Experimental animals were randomly divided into three groups: normal (sham), 25% ethanol, and 25% ethanol + hederagenin (50 mg/kg/day). Each group was orally administered the respective treatments once per day for 21 days. Acetaldehyde dehydrogenase-2 mRNA expression was higher and alcohol dehydrogenase mRNA expression was lower in the ethanol + hederagenin group than those in the ethanol group. Pro-inflammatory cytokines, including TNF-α, IL-6, and cyclooxygenase-2, significantly increased in the ethanol group, but these increases were attenuated by hederagenin. Moreover, Western blot analysis showed increased expression of the apoptosis-associated protein, Bcl-2, and decreased expression of Bax and p53 after treatment with hederagenin. Hederagenin treatment attenuated ethanol-induced increases in activated p38 MAPK and increased the levels of phosphorylated AKT and ERK. Hederagenin alleviated ethanol-induced liver damage through anti-inflammatory and anti-apoptotic activities. These results suggest that hederagenin is a potential candidate for preventing alcoholic liver injury.

Gold Nanoparticles-Based Barcode Analysis for Detection of Norepinephrine

Nanotechnology-based bio-barcode amplification analysis offers an innovative approach for detecting neurotransmitters. We evaluated the efficacy of this method for detecting norepinephrine in normal and oxidative-stress damaged dopaminergic cells. Our approach use a combination of DNA barcodes and bead-based immunoassays for detecting neurotransmitters with surface-enhanced Raman spectroscopy (SERS), and provides polymerase chain reaction (PCR)-like sensitivity. This method relies on magnetic Dynabeads containing antibodies and nanoparticles that are loaded both with DNA barcords and with antibodies that can sandwich the target protein captured by the Dynabead-bound antibodies. The aggregate sandwich structures are magnetically separated from the solution and treated to remove the conjugated barcode DNA. The DNA barcodes are then identified by SERS and PCR analysis. The concentration of norepinephrine in dopaminergic cells can be readily detected using the bio-barcode assay, which is a rapid, high-throughput screening tool for detecting neurotransmitters.

Radical Scavenging Activities of Tannin Extracted from Amaranth (Amaranthus caudatus L.)

This study investigates the bioactivity of tannin from amaranth (Amaranthus caudatus L.) extracts. The antioxidant activities of the extracts from amaranth leaves, flowers, and seeds were evaluated. Tannin from leaves of amaranth has been evaluated for superoxide scavenging activity by using DPPH and ABTS(+) analysis, reducing power, protective effect against H2O2-induced oxidative damage in L-132 and BNL-CL2 cells, and inhibition of superoxide radical effects on HL-60 cells. At a concentration of 100 μg/ml, tannin showed protective effects and restored cell survival to 69.2% and 41.8% for L-132 and BNL-CL2 cells, respectively. Furthermore, at the same concentration, tannin inhibited 41% of the activity of the superoxide radical on HL-60 cells and 43.4% of the increase in nitric oxide levels in RAW 264.7 cells. The expression levels of the antioxidant-associated protein SOD-1 were significantly increased in a concentration-dependent manner in RAW 264.7 cells treated with tannin from amaranth leaves. These results suggest that tannin from the leaves of Amaranthus caudatus L. is a promising source of antioxidant component that can be used as a food preservative or nutraceutical.

Electrochemical Detection of Human Mesenchymal Stem Cell Differentiation on Fabricated Gold Nano-Dot Cell Chips

Human mesenchymal stem cells (MSCs) have the capacity for self-renewal and maintain pluripotency, which is defined by their ability to differentiate into cells such as osteoblasts, neurons, and glial cells. In this study, we report a method for defining the status of human MSCs based on electrochemical detection systems. Gold nano-dot structures were fabricated using a nanoporous alumina mask, and the structural formations were confirmed by scanning electron microscopy (SEM). Human MSCs were allowed to attach to RGD (Arg-Gly-Asp) peptide nanopatterned surfaces, and electrochemical tools were applied to the MSCs attached on the chip surface. The cultured MSCs were shown to differentiate into neural cell types, as indicated by immunocytochemical staining for tyrosine hydroxylase and beta tubulin III. Following treatment with basic fibroblast growth factor (bFGF) for 14 days, most of the B10 cells exhibited bipolar or multipolar morphology with branched processes, and the proportion of B10 cells expressing neuronal cell markers considerably increased. Electrophysiological recordings from MSCs treated with bFGF for 5-14 days were examined with cyclic voltammetry, and the electrochemical signals were shown to increase during differentiation from MSCs to neuronal cells. This human MSC cell line is a useful tool for studying organogenesis, specifically neurogenesis, and in addition, the cell line provides a valuable source of cells for cell therapy. The electrochemical measurement system proposed here could be utilized in electrical cell chips for numerous applications, including cell differentiation, disease diagnosis, drug detection, and on-site monitoring.

Outcome of percutaneous transluminal angioplasty in diabetic patients with critical limb ischaemia

OBJECTIVE

We investigated the clinical outcome of percutaneous transluminal angioplasty (PTA) which has not been fully established in diabetic patients with critical limb Ischaemia (CLI) compared with non-diabetics.

DESIGN AND PATIENTS

A total of 73 limbs of 52 patients (50 limbs of 34 diabetic patients and 23 limbs of 18 non-diabetics) who underwent PTA for CLI (Rutherford-Becker category 4, 5 or 6) were enrolled. Rates of amputation and restenosis, and ankle brachial index (ABI), were assessed before and after PTA during a 36-month follow-up period.

RESULTS

Diabetic patients had a higher rate of major amputations after PTA (10 vs. 0%, P<0.05); however, total amputation (12.0 vs. 8.7%, P=0.62) and restenosis rates (4.0 vs. 8.7%, P=0.38) were not significantly different compared with non-diabetic patients. ABI at 3 months after PTA was significantly improved in both diabetic and non-diabetic patients (0.70±0.20 vs. 0.93±0.19, P<0.01 in diabetic patients; 0.69±0.25 vs. 0.92±0.17, P<0.01 in non-diabetics). Improved ABI was maintained for 36 months in both groups and did not show a significant difference (0.88±0.21 vs. 0.89±0.20, P=0.89).

CONCLUSION

Our results, showing that the outcome of PTA in diabetic patients is not inferior to that in non-diabetics, suggest the potential benefit of primary PTA, instead of bypass surgery, for CLI in diabetic patients who are at high risk of perioperative complications.

In vitro analysis of the anti-cancer activity of mitoxantrone loaded on magnetic nanoparticles

In this study, the anti-tumor activity of mitoxantrone loaded on magnetic nanoparticles (MTMP) was examined using DU145 prostate cancer cells. Composite nanoparticles with an average size of 20 nm were prepared using a chemical co-precipitation technique. The MTMP nanoparticles were cytotoxic to DU145 cells and inhibited cell proliferation. The expression levels of apoptosis related proteins in DU145 cells, including PARP and caspase 3, were increased after MTMP treatment. In this study, the therapeutic potential of MTMP in targeted-therapy against prostate cancer was demonstrated and MTMP was more effective when coupled to drug delivery vehicle than pure mitoxantrone.

Detection of tyrosine hydroxylase in dopaminergic neuron cell using gold nanoparticles-based barcode DNA

Tyrosine hydroxylase, the rate-limiting enzyme of catecholamine biosysthesis, is predominantly expressed in several cell groups within the brain, including the dopaminergic neurons of the substantia nigra and ventral tegmental area. We evaluated the efficacy of this protein-detection method in detecting tyrosine hydroxylase in normal and oxidative stress damaged dopaminergic cells. In this study, a coupling of DNA barcode and bead-based immnunoassay for detecting tyrosine hydroxylaser with PCR-like sensitivity is reported. The method relies on magnetic nanoparticles with antibodies and nanoparticles that are encoded with DNA and antibodies that can sandwich the target protein captured by the nanoparticle-bound antibodies. The aggregate sandwich structures are magnetically separated from solution, and treated to remove the conjugated barcode DNA. The DNA barcodes were identified by PCR analysis. The concentration of tyrosine hydroxylase in dopaminergic cell can be easily and rapidly detected using bio-barcode assay. The bio-barcode assay is a rapid and high-throughput screening tool to detect of neurotransmitter such as dopamine.

Cell chip-based monitoring of toxic effects of cosmetic compounds on skin fibroblast cells

The present study estimated the efficacy of electrochemical detection of imidazolidinyl urea-induced cell toxicity in skin human fibroblast cells (HFF cells). The gold nanopunct structures were fabricated through a nanoporous alumina mask, and the structural formations were confirmed via scanning electron microscopy. The HFF cells were allowed to attach to RGD (Arg-Gly-Asp) peptide nanopatterned surfaces, and electrochemical tools were applied to skin cells attached to the chip surface. The HFF cells evidenced inflammation responses to allergens such as imidazolidinyl urea. The cells were subsequently treated with different concentrations of imidazolidinyl urea for 24 h in culture, which induced a change in the cyclic voltammetry (CV) current peak. Treatment with imidazolidinyl urea induced a loss of cell viability and accelerated inflammation in a concentration-dependent manner. The expression level of inflammation-related proteins such as IL-1 beta were increased in imidazolidinyl urea-treated cells. The CV results demonstrated that imidazolidinyl urea significantly reduced the current peaks in a dose-dependent manner. The results showed that the current peak was reduced in accordance with the increases in imidazolidinyl urea-induced inflammation. In conclusion, the results of this study suggest that the electrochemical-based chip provides crucial information for improvements to a cell chip system for drug screening applications.

Cell chip based monitoring of toxic effects on dopaminergic cell

Oxidative stress has been implicated in pesticide-induced neurotoxicity, base on its role in cascade of biochemical changes that lead to dopaminergic neuronal cell death. The present study examined the role of oxidative stress and the electrochemical detection by polychlorinated biphenyls (PCBs)-induced toxicant in SH-SY5Y cell. The cells were seed in the RED (Arg-Gly-Asp) nanopatterned coating gold substrate and treated with different concentration of PCBs for 24 h in culture, which induced the change of the cyclic voltammetry (CV) current peak. The CV results showed that PCB significantly decreased the current peaks in dose and time-dependent manner. After antioxidant treatment, the CV of the PCB-treated cell chip increased the current peak. Especially, gluthaione and catalase prevent PCB-induced decrease of CV current peak in the cell. The results demonstrated that the current peak decreased by the PCB and recovered by the antioxidant enzyme. In conclusion, results suggest that the electrochemical-based chip provide crucial information to improvement toward a cell chip system for drug screening application.

Detection of dopamine in dopaminergic cell using nanoparticles-based barcode DNA analysis

Nanotechnology-based bio-barcode-amplification analysis may be an innovative approach to dopamine detection. In this study, we evaluated the efficacy of this bio-barcode DNA method in detecting dopamine from dopaminergic cells. Herein, a combination DNA barcode and bead-based immunoassay for neurotransmitter detection with PCR-like sensitivity is described. This method relies on magnetic nanoparticles with antibodies and nanoparticles that are encoded with DNA, and antibodies that can sandwich the target protein captured by the nanoparticle-bound antibodies. The aggregate sandwich structures are magnetically separated from solution, and treated in order to remove the conjugated barcode DNA. The DNA barcodes were then identified via PCR analysis. The dopamine concentration in dopaminergic cells can be readily and rapidly detected via the bio-barcode assay method. The bio-barcode assay method is, therefore, a rapid and high-throughput screening tool for the detection of neurotransmitters such as dopamine.

Surface enhanced Raman scattering of neurotransmitter release in neuronal cells using antibody conjugated gold nanoparticles

This study demonstrated the potential feasibility of using antibody-conjugated gold nanoparticles as highly sensitive and homogeneous sensing probes for biological monitoring of neurotransmitters in neuronal cells. Bands at 1152 and 1322 cm(-1) were also similar to SERS of metal catecholates, and could be assigned to catechol ring vibration and carbon-oxygen stretches.

Proteomic analysis of the protective effects of Platycodi Radix in liver of chronically alcoholic rats

In this study, we examined the effect of Platycodi Radix (PR) supplementation in chronically alcoholic rats. Sprague-Dawley rats were divided into three groups: control group (no alcohol), alcohol group (36.8% of total calories), and 0.3% PR group. The levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were increased by alcohol treatment, and PR supplementation normalized the AST level. Moreover, alcohol-induced cytochrome P450 2E1 was decreased by PR treatment. Proteomic analysis of liver tissues of alcohol-exposed rats and PR-supplemented rats revealed that 50 different proteins functionally characterized as involved with cytoskeleton regulation, signal transduction, cytokine, apoptosis, and reactive oxygen species metabolism showed significant quantitative changes. The expression levels of glutathione S-transferase mu, Bcl-2-like protein, and peroxiredoxin IV were decreased in the alcoholic group, whereas the levels of these proteins were increased more than threefold in the PR group. However, the expression levels of smooth muscle actin, cytochrome P450 2D, mitogen-activated protein kinase 8, and 3alpha-hydroxysteroid dehydrogenase were increased in the alcohol group and were decreased in the PR group. These data suggest that the antioxidant enzymes may play a protective role against alcohol-induced damage via oxidative stress defense mechanisms induced by PR supplementation.

Identification of gliotropic factors that induce human stem cell migration to malignant tumor

Neural stem cells are mobile, are attracted to regions of brain damage, and can migrate a considerable distance to reach a glioma site. However, the molecular basis of the progression of gliotropism to malignant gliomas remains poorly understood. With the use of clinically and histologically assessed glioma cells, we have assessed their protein and gene profiles via proteomics and microarray approaches, and have identified candidate genes from human glioma tissues. This research is expected to provide clues to the molecular mechanisms underlying the migration of neural stem cells (F3 cell) to glioma sites. The expression of 16 proteins was shown to have increased commonly in human glioma tissues. Among them, the expression of annexin A2, TIMP-1, COL11A1, bax, CD74, TNFSF8, and SPTLC2 were all increased in human glioma cells, as confirmed by Western blotting and immunohistochemical staining. In particular, annexin A2 effects an increase in migration toward F3 and glioblastoma cells (U87 cell) in a Boyden chamber migration assay. An ERK inhibitor (PD98057) and a CDK5 inhibitor (rescovitine) inhibited 50% and 90% of annexin A2-induced migration in F3 cells, respectively. A similar chemotactic migration was noted in F3 and U87 cells. These results demonstrated that 7 candidate proteins may harbor a potential glioma tropism factor relevant to the pathology of malignant glioma. These results reveal that this novel molecular approach to the monitoring of glioma may provide clinically relevant information regarding tumor malignancy, and should also prove appropriate for high-throughput clinical screening applications.

Migration of human neural stem cells toward an intracranial glioma

Many in vivo and in vitro studies have demonstrated the targeted migration of neural stem cells (NSC) to infiltrating brain tumors, including malignant glioma, highlighting a potential therapeutic approach. However, there is not enough information to apply this approach to clinical therapy. The most important things in stem cell therapy for brain tumors involve selecting the appropriate neural progenitor type and optimizing the efficiency of the cell engraftment. By histological analysis using two different live-dyes, human NSCs were shown to migrate away from the transplanted site in the direction of the expanding C6 glioma and to intermix with the tumor bed, especially with the tumor core. This intermixing occurred within 7 days when NSCs were implanted into glioma model. The time course of migratory HB1.F5 with the greatest mobility of three NSC lines was as follows. As early as 3 days after transplantation, several NSCs were found leaving the implant site, primarily approaching microsatellites and frontier cells located near the site of NSC implantation. Through 7 days post-transplantation, massive numbers of NSCs continued to be attracted to and interspersed with C6 glioma, and were finally distributed extensively throughout the whole tumor bed, including the core and penumbra of the tumor mass. However, NSCs appeared to penetrate into the tumor mass very well, whereas normal fibroblast cells could not migrate. These findings strengthen the potential for human NSCs as attractive vehicles to improve therapeutic gene delivery to cancer or glioma if they are optimized to selectively kill neoplastic cells.

Identification of proteins that regulate radiation-induced apoptosis in murine tumors with wild type p53

In this study, we investigated the molecular factors determining the induction of apoptosis by radiation. Two murine tumors syngeneic to C3H/HeJ mice were used: an ovarian carcinoma OCa-I, and a hepatocarcinoma HCa-I. Both have wild type p53, but display distinctly different radiosensitivity in terms of specific growth delay (12.7 d in OCa-I and 0.3 d in HCa-I) and tumor cure dose 50% (52.6 Gy in OCa-I and > 80 Gy in HCa-I). Eight-mm tumors on the thighs of mice were irradiated with 25 Gy and tumor samples were collected at regular time intervals after irradiation. The peak levels of apoptosis were 16.1 +/- 0.6% in OCa-I and 0.2 +/- 0.0% in HCa-I at 4 h after radiation, and this time point was used for subsequent proteomics analysis. Protein spots were identified by peptide mass fingerprinting with a focus on those related to apoptosis. In OCa-I tumors, radiation increased the expression of cytochrome c oxidase and Bcl2/adenovirus E1B-interacting 2 (Nip 2) protein higher than 3-fold. However in HCa-I, these two proteins showed no significant change. The results suggest that radiosensitivity in tumors with wild type p53 is regulated by a complex mechanism. Furthermore, these proteins could be molecular targets for a novel therapeutic strategy involving the regulation of radiosensitivity.

Proteomics analysis of apoptosis-regulating proteins in tissues with different radiosensitivity

The aim of this study was to identify of radiosusceptibility proteins in tissues with different radiosensitivity. C3H/HeJ mice were exposed to 10 Gy. The tissues were processed for proteins extraction and were analyzed by 2-dimensional electrophoresis. The proteins were identified by matrix-assisted laser desorption ionizing time-of-flight mass spectrometry and validated by immunohistochemical staining and Western blotting. The peaks of apoptosis levels were 35.3 +/- 1.7% and 0.6 +/- 0.2% in the spleen and the liver, respectively, after ionizing radiation. Analysis of liver tissue showed that the expression level of ROS related proteins such as cytochrome c, glutathione S transferase, NADH dehydrogenase and peroxiredoxin VI increased after radiation. The expression level of cytochrome c increased to 3-fold after ionizing radiation in both tissues. However in spleen tissue, the expression level of various kinds of apoptosis regulating proteins increased after radiation. These involved iodothyronine, CD 59A glycoprotein precursor, fas antigen and tumor necrosis factor -inducible protein TSG-6n precursor after radiation. The difference in the apoptosis index between the liver and spleen tissues is closely associated with the expression of various kinds of apoptosis-related proteins. The result suggests that the expression of apoptosis-related protein and redox proteins play important roles in this radiosusceptibility.

[Protein expression profiles in a rat cirrhotic model induced by thioacetamide]

BACKGROUND/AIMS

The reactive oxygen species from thioacetamide (TAA) induces rat liver cirrhosis that resembles the human disease, and it can serve as a suitable animal model for studying human liver cirrhosis. The aim of this study was to identify the molecular protein signatures via a proteomics approach with using a rat model with TAA-induced liver cirrhosis.

METHODS

Male Wistar rats were treated with 0.3 g/L TAA in their drinking water. The animals were then sacrificed at 9 and 30 weeks after TAA administration. The development of liver cirrhosis was observed with histological study. The livers were processed for proteins extraction and the proteins were analyzed by 2-dimensional electrophoresis. The proteins were identified by matrix-assisted laser desorption ionizing time-of-flight mass spectrometry and this was validated by immunohistochemical staining.

RESULTS

On the proteomics analysis of the liver tissues, a total of 88 proteins showed significant change in their expression between the controls and the cirrhotic rats. When the proteins were categorized by their function, they included ECM/cellular skeleton, cell proliferation/death signal, metabolism, DNA damage/stress and immune response related proteins. The level of expression gradually increased up to 30 weeks for interleukin-6 (IL-6) precursor, transforming growth factor-beta (TGF-beta) induced protein, TIMP-1 and MMP-9. Cytochrome P450 2B, which is required for the metabolic activation of TAA, also showed the same increasing pattern. In contrast, the expression level of the proteins did not show a significant change at 9 weeks, but this increased to 3-fold at 30 weeks for carbonic anhydrase VII, ras related protein Rab 6, Annexin A2, neurofibromatosis type 2 and aldehyde dehydrogenase.

CONCLUSIONS

This study showed that there is a repertoire of proteins during the development of liver cirrhosis via TAA. In this model, IL-6, TGF-beta, MMP-9 and TIMP-1 were reconfirmed as the molecular signatures during the development of TAA-induced liver cirrhosis.

Redox signaling by ionizing radiation in mouse liver

Since radiation treatment has been reappraised in the treatment of hepatic tumors, radiation response in the liver is emerging as an interesting new area of investigation. In this study, identification of the repertoire of signaling proteins was performed using a proteomics approach involving cellular responses of liver tissue to ionizing radiation. Approximately 800 protein spots were detected. Among them, at least 28 proteins showed significant quantitative alterations after radiation. The significantly altered proteins were categorized as those related to reactive oxygen species (ROS) metabolism, metabolic pathway proteins, and G-type proteins. Particularly, the expression levels of proteins related to ROS metabolism, including cytochrome c, glutathione S-transferase Pi, NADH dehydrogenase, and peroxiredoxin VI, were increased after radiation. It is suggested that although radiation initiates cytotoxic effects, it can also induce a radioprotective antioxidant system.

Identification and characterization of a novel transcriptional regulator, MatR, for malonate metabolism in Rhizobium leguminosarum bv. trifolii

A novel gene, matR, located upstream of matABC, transcribed in the opposite direction, and encoding a putative regulatory protein by sequence analysis was discovered from Rhizobium leguminosarum bv. trifolii. The matA, matB, and matC genes encode malonyl-CoA decarboxylase, malonyl-CoA synthetase, and a presumed malonate transporter, respectively. Together, these enzymes catalyze the uptake and conversion of malonate to acetyl-CoA. The deduced amino-acid sequence of matR showed sequence similarity with GntR from Bacillus subtilis in the N-terminal region encoding a helix-turn-helix domain. Electrophoretic mobility shift assay indicated that MatR bound to a fragment of DNA corresponding to the mat promoter region. The addition of malonate or methylmalonate increased the association of MatR and DNA fragment. DNase I footprinting assays identified a MatR binding site encompassing 66 nucleotides near the mat promoter. The mat operator region included an inverted repeat (TCTTGTA/TACACGA) centered -46.5 relative to the transcription start site. Transcriptional assays, using the luciferase gene, revealed that MatR represses transcription from the mat promoter and malonate alleviates MatR-mediated repression effect on the expression of Pmat-luc+ reporter fusion.

The active site and substrates binding mode of malonyl-CoA synthetase determined by transferred nuclear Overhauser effect spectroscopy, site-directed mutagenesis, and comparative modeling studies

The active sites and substrate bindings of Rhizobium trifolii molonyl-CoA synthetase (MCS) catalyzing the malonyl-CoA formation from malonate and CoA have been determined based on NMR spectroscopy, site-directed mutagenesis, and comparative modeling methods. The MCS-bound conformation of malonyl-CoA was determined from two-dimensional-transferred nuclear Overhauser effect spectroscopy data. MCS protein folds into two structural domains and consists of 16 alpha-helices, 24 beta-strands, and several long loops. The core active site was determined as a wide cleft close to the end of the small C-terminal domain. The catalytic substrate malonate is placed between ATP and His206 in the MCS enzyme, supporting His206 in its catalytic role as it generates reaction intermediate, malonyl-AMP. These findings are strongly supported by previous biochemical data, as well as by the site-directed mutagenesis data reported here. This structure reveals the biochemical role as well as the substrate specificity that conservative residues of adenylate-forming enzymes have.

Identification of residues essential for a two-step reaction by malonyl-CoA synthetase from Rhizobium trifolii

Malonyl-CoA synthetase (MCS) catalyses the formation of malonyl-CoA in a two-step reaction consisting of the adenylation of malonate with ATP followed by malonyl transfer from malonyl-AMP to CoA. In order to identify amino acid residues essential for each step of the enzyme, catalysis based on chemical modification and database analysis, Arg-168, Lys-170, and His-206 were selected for site-directed mutagenesis. Glutathione-S-transferase-fused enzyme (GST-MCS) was constructed and mutagenized to make R168G, K170M, R168G/K170M and H206L mutants, respectively. The MCS activity of soluble form GST-MCS was the same as that of wild-type MCS. Circular dichroism spectra for the four mutant enzymes were nearly identical to that for the GST-MCS, indicating that Arg-168, Lys-170 and His-206 are not important for conformation but presumably for substrate binding and/or catalysis. HPLC analysis of products revealed that the intermediate malonyl-AMP is not accumulated during MCS catalysis and that none of the mutant enzymes accumulated it either. Kinetic analysis of the mutants revealed that Lys-170 and His-206 play a critical role for ATP binding and the formation of malonyl-AMP, whereas Arg-168 is critical for formation of malonyl-CoA and specificity for malonyl-AMP. Molecular modelling based on the crystal structures of luciferase and gramicidin S synthetase 1 provided MCS structure which could fully explain all these biochemical data even though the MCS model was generated by comparative modelling.

A gene cluster encoding malonyl-CoA decarboxylase (MatA), malonyl-CoA synthetase (MatB) and a putative dicarboxylate carrier protein (MatC) in Rhizobium trifolii--cloning, sequencing, and expression of the enzymes in Escherichia coli

A gene cluster consisting of three consecutive genes, matABC, was isolated using a probe prepared from amino acid sequence information of Rhizobium trifolii malonyl-CoA synthetase, and was subsequently sequenced. The sequences of matA and matB were overlapped by four base pairs, whereas the intergenic region between matB and matC had 95 base pairs. The upstream region contained DNA sequences which are typical for an Escherichia coli sigma70 promoter, and no other open reading frame was found within 400 bp downstream of matC. The ribosome-binding sites were found 7 to 12 base pairs upstream of each gene. MatA gene encoded a polypeptide of 462 amino acid residues, with deduced molecular mass of 51414 Da. A glutathione-S-transferase-MatA fusion protein has been purified and MatA was shown to have an intrinsic malonyl-CoA decarboxylase activity (Km = 0.47 mM; Vmax = 52 micromol x min(-1) x mg(-1)). MatB encoded a polypeptide of 504 amino acid residues with deduced molecular mass of 54612 Da. MatB was also purified from E. coli transformant carrying the gene cluster. The enzyme was essentially indistinguishable from the wild-type malonyl-CoA synthetase of R. trifolii by the criteria of polyacrylamide gel electrophoresis and biochemical properties. MatC encoded a 46453-Da protein with a high content of hydrophobic residues. The deduced amino acid sequences of matC showed identity to some extent with anaerobic C4-dicarboxylate carrier proteins from E. coli (25%) and Haemophilus influenzae (17%). MatC protein appears to be an integral membrane protein that could function as a malonate carrier. The formation of acetyl-CoA and malonyl-CoA from malonate was confirmed by thin-layer chromatographic analysis. These results strongly suggest that the gene cluster encodes proteins involved in the malonate-metabolizing system, malonate-->malonyl-CoA-->acetyl-CoA, in R. trifolii and that the metabolic pathway in the malonate-rich clover nodule might play an important role in symbiosis.

High-performance reversed-phase chromatographic mapping of 2-pyridylamino derivatives of xyloglucan oligosaccharides

Xyloglucan oligosaccharides from cotton cell walls and tamarind seeds were derivatized with 2-aminopyridine and subsequently separated by reversed-phase chromatography (r.p.c.) using an octadecylsilyl silica stationary phase and aqueous-organic eluents with 0.01% (v/v) trifluoroacetic acid. The chromatographic behavior of the 2-pyridylamino derivatives of xyloglucan oligosaccharides was examined under a wide range of elution conditions, including gradient steepness and shape, initial acetonitrile concentration in the eluent, and pore size of the r.p.c. packings. Relatively steep acetonitrile gradients resulted in poor resolution of the different xyloglucan fragments, which is believed to be the result of acetonitrile-induced conformational changes. Under these circumstances the elution order of the derivatized xyloglucan oligosaccharides was such that the smaller fragments eluted from the column before the larger ones. R.p.c. packing with a 70-A pore size necessitated relatively high acetonitrile concentration in the eluent when compared with 300-A stationary phase. The r.p.c. mapping of 2-pyridylamino derivatives of xyloglucan oligosaccharides was best achieved when both a wide-pore octadecyl-silyl silica stationary phase and a shallow gradient with consecutive linear segments of increasing acetonitrile concentration in the eluent were employed. This combination yielded rapid r.p.c. maps of the xyloglucan fragments from different sources with high separation efficiencies and concomitantly high resolution. The effects of the nature of the sugar residues in the xyloglucan oligomers and their degree of branching on r.p.c. retention and selectivity are also highlighted.