15-Deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) Induces Cell Death Through Caspase-independent Mechanism in A172 Human Glioma Cells

15-Deoxy-(Delta12,14)-prostaglandin J(2) (15d-PGJ(2)) is a naturally occurring cyclopentenone metabolite of prostaglandin D(2) (PGD(2)) and is known as a specific potent ligand for the peroxisome proliferators activator receptor-gamma (PPARgamma). 15d-PGJ(2) inhibits cell growth and induces apoptosis in a number of different cancer cells. However, the underlying mechanism by which 15d-PGJ(2) induces cell death remains to be defined. The present study was undertaken to determine the effect of 15d-PGJ(2) on cell death in A172 human glioma cells. 15d-PGJ(2) caused reactive oxygen species (ROS) generation. 15d-PGJ(2)-induced ROS production and cell death were prevented by the antioxidant N-acetylcysteine. Activation of mitogen-activated protein kinases (MAPK) was not observed in cells treated with 15d-PGJ(2 )and inhibitors of MAPK subfamilies also were not effective in preventing 15d-PGJ(2)-induced cell death. 15d-PGJ(2) treatment caused mitochondrial dysfunction, as evidenced by depolarization of mitochondrial membrane potential. 15d-PGJ(2) induced caspase activation at 24 h of treatment, but the 15d-PGJ(2)-induced cell death was not prevented by caspase inhibitors. The antiapoptotic protein XIAP levels and release of apoptosis inducing factor (AIF) into the cytosol were not altered by 15d-PGJ(2) treatment. Taken together, these findings indicate that 15d-PGJ(2) triggers cell death through a caspase-independent mechanism and ROS production and disruption of mitochondrial membrane potential play an important role in the 15d-PGJ(2)-induced cell death in A172 human glioma cells.

The clinical utility of leptin therapy in metabolic dysfunction

Obesity and diabetes are major public health threats worldwide. Insulin resistance appears to be a significant factor in this global epidemic. In this present review, we have focused on a human model of insulin resistance which embodies many of the metabolic abnormalities that are associated with the morbidity of diabetes and obesity. Lipodystrophy in rodents and humans is a severe model of insulin resistance, and we use a novel therapeutic approach with the administration of the newly discovered leptin to ameliorate many of these metabolic abnormalities. The ability to study the administration of leptin in this setting of severe insulin resistance allows us perform a coveted look into a human condition where metabolic dysfunction can be reversed or controlled.

Methylenetetrahydrofolate reductase A1298C genotypes are associated with the risks of acute lymphoblastic leukaemia and chronic myelogenous leukaemia in the Korean population

Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme involved in folate metabolism, DNA methylation and synthesis. We investigated the association between MTHFR polymorphisms and the risks of acute and chronic leukaemias. MTHFR C677T and A1298C were genotyped in 396 Korean individuals using multiplex polymerase chain reaction/restriction fragment-length polymorphism. They were acute lymphoblastic leukaemia (ALL, n = 89), acute myeloid leukaemia (AML, n = 55), biphenotypic acute leukaemia (n = 12), chronic myelogenous leukaemia (CML, n = 40), and normal controls (n = 200). C677T genotypes were not associated with the risk of each disease. A1298C variants, however, significantly decreased the risks of ALL and CML compared with 1298AA. Odds ratios and 95% confidence intervals of 1298AC and 1298AC + CC were 0.53 (0.31-0.93) and 0.54 (0.31-0.93) in ALL, and 0.34 (0.14-0.80) and 0.40 (0.18-0.89) in CML, respectively, compared with 1298AA. These findings demonstrate that the development of ALL and CML is more dependent on folate status, and more susceptible to DNA instability than that of AML. In addition, A1298C rather than C677T may be a more important genetic risk modifier in leukaemogenesis at least in the Korean population.

Prevalence of erectile dysfunction in Korean men with Type 2 diabetes mellitus

AIMS

We investigated the prevalence and risk factors for developing erectile dysfunction (ED) in 1312 Korean men with diabetes in a multicentre study.

METHODS

We used the modified International Index for Erectile Function-5 criteria to identify mild, moderate and complete ED. A standardized face-to-face questionnaire was used by trained interviewers, and validated against telephone interviews. We recorded the duration of diabetes, level of glycaemic control, vital signs, complications, exercise and alcohol and smoking habits, and diabetes treatments used. Results The mean age and median duration of diabetes were 53.8 +/- 6.65 and 6 years (range 1-43), respectively. The mean HbA(1c) and fasting glucose levels were 7.9 +/- 1.65% and 8.6 +/- 2.82 mmol/l, respectively. The overall prevalences of mild, moderate, complete ED and all ED (mild-to-complete) were 20.1, 19.5, 25.8 and 65.4%, respectively. ED was more common with age, reaching 79.3% in men aged > 60 years. Subjects aged > 60 years and with a duration of diabetes > 10 years were at greatest risk for all ED (OR = 10.4, 95% CI 5.8-18.5, P < 0.001) and complete ED (OR = 13.2, 95% CI 7.3-23.9, P < 0.001) when compared with the reference group (age 40-50 years with duration < 6 years). Age, duration of diabetes, HbA(1c), insulin use, neuropathy and macrovascular complications were positively associated with ED, but alcohol consumption and exercise habits were negatively associated.

CONCLUSIONS

The prevalence of complete ED was approximately six times higher than in the general population.

Intussusception after gastric surgery

Intussusception following gastric surgery is a rare postoperative complication. It may develop in clinical situations following gastroenterostomy, Billroth II gastric surgery with or without Braun anastomosis, or Roux-en-Y gastrojejunostomy. The patients may present with either an acute surgical emergency or with a chronic, relapsing form. The mortality may be up to 50 % in these cases if not treated appropriately, but little is known about the mechanism underlying the condition. Early diagnosis with a high index of suspicion and prompt treatment of the acute form are therefore important. Surgical reduction with laparotomy is mandatory, although definitive corrective and preventative measures have not yet been established.

Physical mapping and microsynteny of Brassica rapa ssp. pekinensis genome corresponding to a 222 kbp gene-rich region of Arabidopsis chromosome 4 and partially duplicated on chromosome 5

We constructed a bacterial artificial chromosome (BAC) library, designated as KBrH, from high molecular weight genomic DNA of Brassica rapa ssp. pekinensis (Chinese cabbage). This library, which was constructed using HindIII-cleaved genomic DNA, consists of 56,592 clones with average insert size of 115 kbp. Using a partially duplicated DNA sequence of Arabidopsis, represented by 19 and 9 predicted genes on chromosome 4 and 5, respectively, and BAC clones from the KBrH library, we studied conservation and microsynteny corresponding to the Arabidopsis regions in B. rapa ssp. pekinensis. The BAC contigs assembled according to the Arabidopsis homoeologues revealed triplication and rearrangements in the Chinese cabbage. In general, collinearity of genes in the paralogous segments was maintained, but gene contents were highly variable with interstitial losses. We also used representative BAC clones, from the assembled contigs, as probes and hybridized them on mitotic (metaphase) and/or meiotic (leptotene/pachytene/metaphase I) chromosomes of Chinese cabbage using bicolor fluorescence in situ hybridization. The hybridization pattern physically identified the paralogous segments of the Arabidopsis homoeologues on B. rapa ssp. pekinensis chromosomes. The homoeologous segments corresponding to chromosome 4 of Arabidopsis were located on chromosomes 2, 8 and 7, whereas those of chromosome 5 were present on chromosomes 6, 1 and 4 of B. rapa ssp. pekinensis.

Induction of proinflammatory mediators requires activation of the TRAF, NIK, IKK and NF-kappaB signal transduction pathway in astrocytes infected with Escherichia coli

Escherichia coli is associated with inflammation in the brain. To investigate whether astrocytes are involved in E. coil-induced inflammation, we assessed the levels of expression of proinflammatory mediators produced by E. coli-infected astrocytes. E. coli infection in primary human astrocytes and cell lines increased expression of the CXC chemokine IL-8/GRO-alpha, the CC chemokine MCP-1, TNF-alpha, and iNOS. E. coli infection activated p65/p50 heterodimeric NF-kappaB and concurrently decreased the signals of IkappaBalpha. Blocking the NF-kappaB signals by IkappaBalpha-superrepressor-containing retrovirus or antisense p50 oligonucleotide transfection resulted in down-regulation of expression of the proinflammatory mediators. Furthermore, superrepressors of IkappaBalpha, IkappaB kinase (IKK) or NF-kappaB inducing kinase (NIK) inhibited the up-regulated expression of the downstream target genes of NF-kappaB such as IL-8 and MCP-1, and superrepressors of TNF receptor-associated factor (TRAF)2 and TRAF5 also inhibited expression of the E. coli-induced target genes of NF-kappaB. These results indicate that proinflammatory mediators such as the CXC chemokine IL-8/GRO-alpha, the CC chemokine MCP-1, TNF-alpha, and iNOS can be expressed in E. coli-infected astrocytes via an NF-kappaB pathway, suggesting that these mediators may contribute to inflammation in the brain, including infiltration of inflammatory cells.

Influence of VEGF gene polymorphisms on the severity of ankylosing spondylitis

OBJECTIVES

To investigate the role of polymorphisms of the vascular endothelial growth factor (VEGF) gene in susceptibility to ankylosing spondylitis (AS), and their relationship to clinical features and radiographic severity.

METHODS

This study included 157 patients with AS and 140 healthy unrelated controls. Polymorphisms of the VEGF gene were analysed by the polymerase chain reaction (PCR)-restriction fragment length polymorphism assay and amplification refractory mutation system-PCR. Haplotypes were reconstructed using the Bayesian algorithm. Radiographic severity was assessed by the Bath Ankylosing Spondylitis Radiological Index (BASRI).

RESULTS

The genotype frequencies of the polymorphisms were in Hardy-Weinberg equilibrium. The distributions of genotypes and alleles did not differ between AS patients and controls. Among the six haplotypes reconstructed based on the tight linkage disequilibrium at positions -2578, -1154 and -634 (pairwise linkage disequilibrium coefficient, r = 0.361-0.706), no haplotype was associated with susceptibility to AS. Clinical features were analysed for the four haplotypes (CGC, CGG, AAG, AGG) which were prevalent. In carriers of the AGG haplotype, the frequency of cervical spine involvement was significantly higher (P = 0.002, P(corr) = 0.036) and that of patients showing a BASRI score >6 was also higher (P = 0.025, P(corr) = 0.45).

CONCLUSIONS

This study demonstrates that polymorphisms of the VEGF gene may contribute to disease severity in AS.

Electrical measurement of moisturizing effect on skin hydration and barrier function in psoriasis patients

Transepidermal water loss (TEWL) in psoriatic skin lesions seems to be related to the severity of the psoriasis, and the electrical capacitance and conductance of the skin are indicators of the hydration level of the stratum corneum. We compared the characteristics of these electrical measurements, in assessing the persistent effect of a moisturizing cream on skin hydration and barrier function in psoriasis patients. Seventeen Korean psoriasis patients were recruited. Their right leg was treated with the moisturizer twice daily for 6 weeks, while their left leg was used as the control site. For each patient, one psoriatic plaque on each leg was selected as the involved psoriatic lesion. Uninvolved psoriatic skin was regarded as the apparently healthy looking skin 4-5 cm away from the periphery of the psoriatic lesion. The TEWL, electrical capacitance and conductance were measured, in order to evaluate the barrier function and hydration level of the stratum corneum. The clinical and biophysical data for each patient were recorded at the start of the study and after 2, 4 and 6 weeks. The degree of skin dryness at the applied area improved progressively. The electrical capacitance at the treated psoriatic lesion increased significantly after 2 weeks, and this improvement was maintained during the entire study period. However, no noticeable change was observed in the electrical conductance. The TEWL showed an inverse pattern to that of the skin capacitance, decreasing during the study period. The skin capacitance and TEWL exhibited good correlation with the visual assessment of skin dryness, but the skin conductance did not. Our data suggest that electrical capacitance and TEWL may be useful in the evaluation of the effect of a moisturizer on the hydration status and barrier function of psoriatic skin.

Structural determination of the low-coverage phase of Al on Si(001) surface

The atomic structure of Al layer on Si(001)-(2 x 1) surface has been studied by coaxial impact collision ion scattering spectroscopy. When 0.5 monolayer (ML) of Al atoms are adsorbed on Si(001) at room temperature, it is found that Al adatoms are dimerized and Al ad-dimers are oriented parallel to the underlying Si dimers at the position of centering T3 site with a height of 1.02 Angstroms from the first layer of Si(001). The bond length of the Al dimer is 2.67 Angstroms. With increasing Al coverage up to one ML, Al ad-dimers still occupied near T3 site and the next favorable site is near HH site.

A new Hypocrea strain producing harzianum A cytotoxic to tumour cell lines

AIMS

To identify a new fungal strain, Hypocrea sp. F000527 producing a trichothecene metabolite, harzianum A, and to evaluate its cytotoxicity to tumour cell lines.

METHODS AND RESULTS

A fungal strain, F000527, with cytotoxic activity was identified as a new Hypocrea strain based on morphological characteristics and internal transcribed spacers rDNA sequence data. Harzianum A was isolated from wheat bran culture by 50% acetone extraction, silica gel chromatography, Sephadex LH-20 chromatography and HPLC. The chemical structures were determined by ESI- or HRFAB-MS and (1)H and (13)C-NMR analyses. Harzianum A showed cytotoxicity to HT1080 and HeLa cell lines with IC(50) value of 0.65 and 5.07 Łg ml(-1) respectively.

CONCLUSIONS

Harzianum A with a chemical formula of C(23)H(28)O(6) was isolated from a new Hypocrea strain and showed moderate to strong cytotoxicity to human cancer cell lines.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report of the production of cytotoxic harzianum A by a new Hypocrea strain.

Genetic analysis of microsomal epoxide hydrolase gene and its association with lung cancer risk

The human microsomal epoxide hydrolase (EH) gene contains polymorphic alleles, which may be linked to increased risk for tobacco-related lung cancer. The purpose of this study is to screen new polymorphisms and determine whether these polymorphisms can be used to predict individual susceptibility to lung cancer. The polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis was used to screen for polymorphisms in the coding region of the EH gene. Eleven polymorphisms, including previously reported polymorphisms, were identified and the prevalence of these variants was assessed in at least 50 healthy Caucasians and African-Americans. Among the 11 polymorphisms, the prevalence of the amino acid-changing EH polymorphisms in codons 43, 113 and 139 was examined in 182 Caucasian incident cases with primary lung cancer, as well as in 365 frequency-matched controls to examine the role of EH polymorphisms in lung cancer risk. A significant increase in lung cancer risk was observed for predicted high EH activity genotypes (odds ratio (OR) 2.3, 95% confidence interval (CI) 1.2-4.3) as compared with low EH activity genotypes. This association was more pronounced among patients with lung adenocarcinoma (OR 4.7, 95% CI 1.7-13.1). These results suggest that the EH polymorphism plays an important role in lung cancer risk and is linked to tobacco smoke exposure.

Structural analysis of the reconstructed Si(001)-C surface

The atomic structure of reconstructed Si(001)c(4 x 4)-C surface has been studied by coaxial impact collision ion scattering spectroscopy. When the 100L of ethylene (C(2)H(4)) molecules have been exposed on Si(001)-(2 x 1) surface at 700 degrees C, it is found that C atoms cause the ordering of missing Si dimer defects and occupy the fourth layer of Si(001) directly below the bridge site. Our results provide the support for the previous model in which a missing dimer structure is accompanied by C incorporation into the subsurface.

Phenotypic perturbation of B cells in the Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is an X-linked immunodeficiency/platelet disease due to mutations of WASP, a cytoskeletal regulatory protein of blood cells. Patients exhibit a range of immune defects generally attributed to defective T-cell function, including poor response to immunization, skewed immunoglobulin isotypes, eczema, recurrent infections, autoimmune disease and increased frequency of malignancies. Here we show a deficit of total B-cells in WAS patients of various ages and identify phenotypic perturbations involving complement receptors and CD27. Whereas B-cells of normal healthy donors are overwhelmingly CD21/CD35-positive, B-cells expressing these receptors are significantly reduced in number in WAS patients, and their paucity may cause suboptimal antigen capture and presentation. The frequencies of IgD(-) and IgG(+) patient B-cells were not different from healthy donors (although absolute numbers were decreased), indicating that isotype switching is occurring. In contrast, the frequency of cells positive for CD27, the marker of post germinal centre B-cells, was significantly decreased even among isotype-switched cells, and B-cells resembling germinal centre progenitors (CD10(+)CD27(-)CD38(bright)) were more frequent in adult patients, suggesting impaired germinal centre maturation/differentiation. The documentation of these phenotypic perturbations and deficit of total cells suggest that defects intrinsic to B-cells contribute to the impaired humoral immunity that characterizes this disease.

Mutation spectrum of the glucose-6-phosphatase gene and its implication in molecular diagnosis of Korean patients with glycogen storage disease type Ia

Glycogen storage disease type Ia (GSD Ia; MIM 232200) is an autosomal recessive inherited metabolic disorder resulting from a deficiency of the microsomal glucose-6-phosphatase (G6Pase), the enzyme that catalyzes the terminal step in gluconeogenesis and glycogenolysis. Various mutations in the G6Pase gene (G6PC) have been found in patients with GSD Ia. To elucidate the spectrum of the G6PC gene mutations, 13 unrelated Korean patients with GSD Ia were analyzed. We were able to identify mutant alleles in all patients, including three known mutations (727G > T, G122D, and T255I) and two novel mutations (P178A and Y128X). The frequency of the 727G > T mutation in Korean patients with GSD Ia was 81% (21/26), which was slightly lower than that (86-92%) in Japanese but much higher than that (44.4%) in Taiwan Chinese. Except one, all patients were either homozygous (9/13) or compound heterozygous (3/13) for the 727G > T mutation; the only patient without the 727G > T mutation was a compound heterozygote for the G122D and Y128X mutations. Our findings suggest that a DNA-based test can be used as the initial diagnostic approach in Korean patients clinically suspected to have GSD Ia, thereby avoiding invasive liver biopsy.

IKr channel blockers: novel antiarrhythmic agents

There have been extensive efforts to develop I(Kr) channel blockers as a new antiarrhythmic agent for atrial or ventricular fibrillation, since it was demonstrated that selective blockade of the rapidly activating delayed rectifier K+ channel (I(Kr)) in the heart is not deleterious for the total mortality in fatal ventricular arrhythmia patients. Among them, dofetilide and KCB-328 blocks the I(Kr) specifically. Therefore, it increases the action potential duration (APD) selectively. Ibutilide, trecetilide, nifekalant, dronedarone, BRL-32872, H345/52 and ersentilide block the I(Kr). However, they modify also other cardiac channels or receptors. The frequency dependence of the compounds in prolonging the APD varies from the strong reversed tendency of dofetilide to the relatively neutral profile of KCB-328 and BRL-32872. Every compound reported so far has a proarrhythmic potential of torsade de pointes induction under certain conditions, although depending on the structure, the intensity may be somewhat different. In the coming decade, efforts to improve the reverse frequency dependence profile of the I(Kr) blockers by optimizing the onset and recovery time constant of the HERG block (e.g. KCB-328, vesnarinone) or the balance between the block of I(Kr) and Ca++ channels in the heart (e.g. BRL-32872, H 345/52) to eliminate the proarrhythmic potential of the currently known I(Kr) blockers are warranted. Further trials are also needed to discover more favorable compounds with multiple receptors including I(Kr) (e.g. nifekalant, dronedarone) for treating ventricular arrhythmias.

Characterization of the distinct orthotopic bone-forming activity of 14 BMPs using recombinant adenovirus-mediated gene delivery

Efficacious bone regeneration could revolutionize the clinical management of bone and musculoskeletal disorders. Although several bone morphogenetic proteins (BMPs) (mostly BMP-2 and BMP-7) have been shown to induce bone formation, it is unclear whether the currently used BMPs represent the most osteogenic ones. Until recently, comprehensive analysis of osteogenic activity of all BMPs has been hampered by the fact that recombinant proteins are either not biologically active or not available for all BMPs. In this study, we used recombinant adenoviruses expressing the 14 types of BMPs (AdBMPs), and demonstrated that, in addition to currently used BMP-2 and BMP-7, BMP-6 and BMP-9 effectively induced orthotopic ossification when either AdBMP-transduced osteoblast progenitors or the viral vectors were injected into the quadriceps of athymic mice. Radiographic and histological evaluation demonstrated that BMP-6 and BMP-9 induced the most robust and mature ossification at multiple time points. BMP-3, a negative regulator of bone formation, was shown to effectively inhibit orthotopic ossification induced by BMP-2, BMP-6, and BMP-7. However, BMP-3 exerted no inhibitory effect on BMP-9-induced bone formation, suggesting that BMP-9 may transduce osteogenic signaling differently. Our findings suggest that BMP-6 and BMP-9 may represent more effective osteogenic factors for bone regeneration.

Transcription factor decoy for AP-1 reduces mesangial cell proliferation and extracellular matrix production in vitro and in vivo

Diabetic nephropathy is characterized by an expansion of glomerular mesangium, caused by mesangial cell proliferation and excessive accumulation of extracellular matrix (ECM) proteins, which eventually leads to glomerulosclerosis and renal failure. Activator protein-1 (AP-1), a transcription factor, is implicated in the transcriptional regulation of a wide range of genes participating in cell proliferation and ECM production. This investigation was undertaken to test the hypothesis that AP-1 plays an important role in ECM gene expression, and to develop a molecular therapeutic strategy based on decoy oligodeoxynucleotides (ODN). In this report, we show that transfection with AP-1 decoy ODN strongly inhibits high glucose- and angiotensin II-induced cell proliferation and expression of ECM genes in cultured mesangial cells in vitro. Administration of AP-1 decoy ODN into streptozotocin-induced diabetic rat kidney in vivo using the hemagglutinating virus of Japan (HVJ)-liposome method virtually abolished TGF-beta1 and plasminogen activator inhibitor-1 expression. Our results collectively indicate that AP-1 activation is crucial for mesangial cell proliferation and ECM production in response to high glucose and angiotensin II. Moreover, use of stable AP-1 decoy ODN combined with the highly effective HVJ-liposome method provides a novel potential molecular therapeutic strategy for the prevention of diabetic nephropathy.

VEGF gene polymorphisms and susceptibility to rheumatoid arthritis

OBJECTIVES

To investigate polymorphisms of the VEGF gene in patients with rheumatoid arthritis (RA), their relationship to clinical features and the radiographic progression of joint disease.

METHODS

One hundred and forty patients with RA and 149 healthy unrelated controls were recruited. We examined four polymorphisms of the VEGF gene which are reported to be associated with production of vascular endothelial growth factor (VEGF), using polymerase chain reaction (PCR) restriction fragment length polymorphism assay and amplification refractory mutation system (ARMS) PCR. Haplotypes were predicted by Bayesian algorithm using the Phase program.

RESULTS

All four polymorphisms were in Hardy-Weinberg equilibrium in both patients and controls. The frequency of the 936 T allele, which has been associated with lower production of VEGF, was significantly increased in RA patients compared with controls (22.7 vs 13.4%, P = 0.002). The frequencies of two haplotypes (CGCT and AAGT) which were predicted using the Phase program were significantly increased in RA patients compared with controls [33 vs 14%, odds ratio (OR) 2.636, 95% confidence interval (CI) 1.38-5.04 for CGCT; 17 vs 6%, OR 3.08, 95% CI 1.20-7.92 for AAGT]. The carriers of the susceptible haplotypes in RA patients had a younger age at disease onset but did not show a difference in the progression rate of radiographic joint destruction.

CONCLUSIONS

Our data suggest that the VEGF gene may play a role in the development of RA

Construction of a BAC library of Korean ginseng and initial analysis of BAC-end sequences

We estimated the genome size of Korean ginseng (Panax ginseng C.A. Meyer), a medicinal herb, constructed a HindIII BAC library, and analyzed BAC-end sequences to provide an initial characterization of the library. The 1C nuclear DNA content of Korean ginseng was estimated to be 3.33 pg (3.12 x 10(3) Mb). The BAC library consists of 106,368 clones with an average size of 98.61 kb, amounting to 3.34 genome equivalents. Sequencing of 2167 BAC clones generated 2492 BAC-end sequences with an average length of 400 bp. Analysis using BLAST and motif searches revealed that 10.2%, 20.9% and 3.8% of the BAC-end sequences contained protein-coding regions, transposable elements and microsatellites, respectively. A comparison of the functional categories represented by the protein-coding regions found in BAC-end sequences with those of Arabidopsis revealed that proteins pertaining to energy metabolism, subcellular localization, cofactor requirement and transport facilitation were more highly represented in the P. ginseng sample. In addition, a sequence encoding a glucosyltransferase-like protein implicated in the ginsenoside biosynthesis pathway was also found. The majority of the transposable element sequences found belonged to the gypsy type (67.6%), followed by copia (11.7%) and LINE (8.0%) retrotransposons, whereas DNA transposons accounted for only 2.1% of the total in our sequence sample. Higher levels of transposable elements than protein-coding regions suggest that mobile elements have played an important role in the evolution of the genome of Korean ginseng, and contributed significantly to its complexity. We also identified 103 microsatellites with 3-38 repeats in their motifs. The BAC library and BAC-end sequences will serve as a useful resource for physical mapping, positional cloning and genome sequencing of P. ginseng.

Advantages of the circular dumbbell decoy in gene therapy and studies of gene regulation

Decoy oligodeoxynucleotides (ODN) that can reduce the trans-activity of transcription factors may be highly useful in gene therapy and the study of transcriptional regulation. Several different types of these double-stranded DNA decoys have been developed, including unmodified oligonucleotide duplexes, alphabeta-anomeric oligonucleotides, and oligonucleotide duplexes with methylphosphonate- and phosphorothioate-modified linkages. The latter ODNs have been particularly extensively studied but suffer from a number of limitations, including their insensitivity to polymerases, their lack of sequence specificity, and their tendency to activate immune responses. To resolve these problems, circular dumbbell (CD) double-stranded ODNs were developed. These CD ODNs are constructed by the circularization of the 3' and 5' ends of the oligonucleotides and enzymatic ligation. They exhibit high resistance to nucleases, are easily taken up by cells, and have a nontoxic unmodified backbone that resembles natural DNA. In this article, we review the method of constructing CD ODNs and their advantages compared to other modified ODNs for use as transcription decoys.