Facile and precise quantitative determination of silicon in naphtha by inductively coupled plasma-optical emission spectroscopy

The amount of silicon in naphtha must be controlled because it results in silica deposits in vehicle components, such as spark plugs, catalytic converters, and oxygen sensors, which can lead to fuel economy degradation, increased emissions, and damage to catalytic converters. Naphtha has low specific gravity and high volatility; plasma does not form during analysis using inductively coupled plasma-optical emission spectrometry. Therefore, the analysis of silicon in naphtha has been conducted using a dilution method with organic solvents. On the other hand, a high dilution factor increases the LOQ (limit of quantitation), making it difficult to analyse below 100 ppb. In this study, propylene glycol monomethyl ether acetate (PGMEA) was used to solve this problem because it has excellent naphtha solubility, low volatility, and is used widely in semiconductor processing. A LOQ and LOD (limit of detection) of up to 3.3 ppb and 1.0 ppb, respectively, could be achieved using a concentration method by diluting naphtha in PGMEA and heating it. In addition, the reference materials were prepared with octamethylcyclotetrasiloxane to ensure analysis accuracy; excellent results were obtained with an 88% recovery rate.

Laponite-Mediated Copper Metallization by Palladium Intercalation

An alternative catalytic method was employed using the reduction of Pd ions on the surface of cetyltrimethylammonium bromide (CTAB) treated laponite to initiate the electroless plating of copper; the deposition features of the Pd nanoparticles produced were investigated in detail. Results indicated intercalation and reduction of Pd nanoparticles occurred at room temperature and involved interaction between the laponite and the cetyltrimethylammonium cationic templates. Organic species and amount on laponite were optimized to adjust silicate platelet interlayer distances and platelet organophilic properties. Intercalation of Pd nanoparticles occurred between the magnesium silicate layers of laponite and this was dependent on pre-treatment and impregnation times. As impregnation is a method of producing heterogeneous catalysts, we considered Pd nanoparticles on laponite templates could catalyze the electroless deposition of Cu to initiate metallization. Cu films fabricated on laponite templates exhibited excellent surface roughness (˜1.7 nm) and low resistivity (˜3.42 μΩ). The devised approach enabled the facile formation of a network suitable for Cu metallization without causing substrate damage and produced metal surfaces with excellent flatness and resistivity.

Investigation of Copper Etching with a Ferric Nitrate Solution

Copper has unique properties, such as low electrical resistivity, that are exploited in a number of applications, including an interconnect layer in integrated circuits and microelectronic devices. Etching techniques are essential for the fabrication of fine structures, devices, and circuits. This article addresses the methods of copper etching with an emphasis on approaches using ferric nitrate. Potentiodynamic polarization tests using benzotriazole as an inhibitor showed that ferric nitrate has higher inhibition efficiency than conventional etchants. This is because benzotriazole in a ferric nitrate solution is adsorbed on the copper surface to a greater extent than in a ferric chloride and cupric chloride solution, as confirmed by Fourier transform infrared analysis. Quantitative atomic force microscopy characterization showed that good surface quality with significantly lower surface roughness can be obtained from a copper film etched in a ferric nitrate solution, which has potential use in microelectronics manufacturing.

Impact of Buffer Layer Process and Na on Shunt Paths of Monolithic Series-connected CIGSSe Thin Film Solar Cells

The illuminated current-voltage characteristics of Cu(In,Ga)(S,Se)₂ (CIGSSe) thin film solar cells fabricated using two different buffer layer processes: chemical bath deposition (CBD) and atomic layer deposition (ALD) were investigated. The CIGSSe solar cell with the ALD buffer showed comparable conversion efficiency to the CIGSSe solar cell with CBD buffer but lower shunt resistance even though it showed lower point shunt defect density as measured in electroluminescence. The shunt paths were investigated in detail by capturing the high-resolution dark lock-in thermography images, resolving the shunt resistance contributions of the scribing patterns (P1, P3), and depth profiling of the constituent elements. It was found that the concentration of Na from the soda-lime glass substrate played a key role in controlling the shunt paths. In the ALD process, Na segregated at the surface of CIGSSe and contributed to the increase in the shunt current through P1 and P3, resulting in a reduction in the fill factor of the CIGSSe solar cells.

Electro-spray deposition of a mesoporous TiO2 charge collection layer: toward large scale and continuous production of high efficiency perovskite solar cells

The spin-coating method, which is widely used for thin film device fabrication, is incapable of large-area deposition or being performed continuously. In perovskite hybrid solar cells using CH(3)NH(3)PbI(3) (MAPbI(3)), large-area deposition is essential for their potential use in mass production. Prior to replacing all the spin-coating process for fabrication of perovskite solar cells, herein, a mesoporous TiO(2) electron-collection layer is fabricated by using the electro-spray deposition (ESD) system. Moreover, impedance spectroscopy and transient photocurrent and photovoltage measurements reveal that the electro-sprayed mesoscopic TiO(2) film facilitates charge collection from the perovskite. The series resistance of the perovskite solar cell is also reduced owing to the highly porous nature of, and the low density of point defects in, the film. An optimized power conversion efficiency of 15.11% is achieved under an illumination of 1 sun; this efficiency is higher than that (13.67%) of the perovskite solar cell with the conventional spin-coated TiO(2) films. Furthermore, the large-area coating capability of the ESD process is verified through the coating of uniform 10 × 10 cm(2) TiO(2) films. This study clearly shows that ESD constitutes therefore a viable alternative for the fabrication of high-throughput, large-area perovskite solar cells.

Permeability- and Surface-Energy-Tunable Polyurethane Acrylate Molds for Capillary Force Lithography

A permeability- and surface-energy-controllable polyurethane acrylate (PUA) mold, a "capillary-force material (CFM)" mold, is introduced for capillary-force lithography (CFL). In CFL, the surface energy and gas permeability of the mold are crucial. However, the modulation of these two main factors at a time is difficult. Here, we introduce new CFM molds in which the surface energy and permeability can be modified by controlling the degree of cross-linking of the CFM. As the degree of cross-linking of the CFM mold increases, the surface energy and air permeability decrease. The high average functionality of the mold material makes it possible to produce patterns relatively finely and rapidly due to the high rate of capillary rise and stiffness, and the low functionality allows for patterns to form on a curved surface with conformal contact. CFMs with different functionality and controllable-interfacial properties will extend the capabilities of capillary force lithography to overcome the geometric limitations of patterning on a scale below 100 nm and micro- and nanopatterning on the curved region.

Trastuzumab for the treatment of HER2-positive metastatic adenocarcinoma of the stomach or gastro-oesophageal junction

This paper presents a summary of the evidence review group (ERG) report into trastuzumab for the treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic adenocarcinoma of the stomach (mGC) or gastro-oesophageal junction. HER2 positivity is defined by immunohistochemistry (IHC)3+ or IHC2+/fluorescence in situ hybridisation (FISH)+. The decision problem addressed was the testing of the whole mGC population with IHC and, for IHC2+ patients, also with FISH, followed by treatment of HER2-positive patients with trastuzumab combined with cisplatin and either capecitabine or 5-fluorouracil (5-FU) [HCX (trastuzumab, cisplatin, capecitabine)/fluorouracil (F)] compared with current standard NHS therapy. The manufacturer's submission contained direct evidence from the ToGA trial, a well-conducted, multinational, phase III randomised controlled trial (RCT) that compared HCX/F with cisplatin and a fluoropyrimidine alone [cisplatin, capecitabine (CX)/F]. HCX/F showed statistically significantly better overall survival in the European Medicines Agency-licensed population subgroup (74%) (hazard ratio 0.65, 95% confidence interval 0.51 to 0.83), corresponding to median survival of 16 months versus 11.8 months. No other evidence exists for the efficacy of any therapy in a known HER2-positive mGC population; other comparisons extrapolate from trials in mixed HER2 status populations. The ERG accepted the manufacturer's view that a meaningful network meta-analysis to establish a comparison for HCX/F compared with current standard NHS therapy [epirubicin, cisplatin, capecitabine (ECX)/epirubicin, oxaliplatin, capecitabine (EOX)/epirubicin, cisplatin, 5-FU (ECF)] was not possible, but was unconvinced by arguments advanced in the alternative narrative synthesis. These involved disregarding evidence from a meta-analysis and interpreting non-significant results of small RCTs comparing epirubicin-containing triplets with cisplatin, 5-FU (CF)/capecitabine (X) doublets as evidence of no difference between triplet and doublet regimens. The high CX/F dose in the ToGA trial was an additional basis for the contention of equivalence. An appropriate de novo economic evaluation, including an economic model that separately compared HCX or trastuzumab, cisplatin, 5-FU (HCF) with the triplet regimens ECX, EOX and ECF, based on a simple, three-state cohort model (progression-free, disease, progression and death), was submitted. Utility weights were applied to estimate quality-adjusted life-years (QALYs). Costs were assessed from an NHS perspective, and incorporated the acquisition and monitoring costs of the alternative regimens, HER2 testing, adverse events and other supportive care costs. An 8-year time horizon was used to represent a lifetime analysis. Results from the ToGA trial were combined with a series of assumptions on relative treatment effects and testing strategies. The manufacturer's results produced an incremental cost-effectiveness ratio (ICER) of £ 53,010 per QALY for HCX versus ECX. Although the manufacturer undertook a detailed set of sensitivity analyses, several alternative model assumptions were not evaluated. The ERG undertook a series of alternative base-case analyses. As a result of these analyses, EOX replaced ECX as the appropriate comparator, and the ICER for the comparison of HCX vs EOX increased to between £ 66,982 and £ 71,636 per QALY. The impact of implementation of alternative testing strategies remained unclear. There is also considerable uncertainty surrounding the true estimate of effectiveness for the comparison between triplet regimens containing epirubicin (ECX/ECF/EOX) and doublet CX/F regimens. Consequently, the view of the ERG was that there is insufficient evidence on the efficacy of HCX/F compared with current NHS standard therapy for an ICER to be determined with any degree of certainty.

Trastuzumab for the treatment of HER2- positive metastatic adenocarcinoma of the stomach or gastro-oesophageal junction

This paper presents a summary of the evidence review group (ERG) report into trastuzumab for the treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic adenocarcinoma of the stomach (mGC) or gastro-oesophageal junction. HER2 positivity is defined by immunohistochemistry (IHC)3+ or IHC2+/fluorescence in situ hybridisation (FISH)+. The decision problem addressed was the testing of the whole mGC population with IHC and, for IHC2+ patients, also with FISH, followed by treatment of HER2-positive patients with trastuzumab combined with cisplatin and either capecitabine or 5-fluorouracil (5-FU) [HCX (trastuzumab, cisplatin, capecitabine)/fluorouracil (F)] compared with current standard NHS therapy. The manufacturer’s submission contained direct evidence from the ToGA trial, a well-conducted, multinational, phase III randomised controlled trial (RCT) that compared HCX/F with cisplatin and a fluoropyrimidine alone [cisplatin, capecitabine (CX)/F]. HCX/F showed statistically significantly better overall survival in the European Medicines Agency-licensed population subgroup (74%) (hazard ratio 0.65, 95% confidence interval 0.51 to 0.83), corresponding to median survival of 16 months versus 11.8 months. No other evidence exists for the efficacy of any therapy in a known HER2-positive mGC population; other comparisons extrapolate from trials in mixed HER2 status populations. The ERG accepted the manufacturer’s view that a meaningful network meta-analysis to establish a comparison for HCX/F compared with current standard NHS therapy [epirubicin, cisplatin, capecitabine (ECX)/epirubicin, oxaliplatin, capecitabine (EOX)/epirubicin, cisplatin, 5-FU (ECF)] was not possible, but was unconvinced by arguments advanced in the alternative narrative synthesis. These involved disregarding evidence from a meta-analysis and interpreting non-significant results of small RCTs comparing epirubicin-containing triplets with cisplatin, 5-FU (CF)/capecitabine (X) doublets as evidence of no difference between triplet and doublet regimens. The high CX/F dose in the ToGA trial was an additional basis for the contention of equivalence. An appropriate de novo economic evaluation, including an economic model that separately compared HCX or trastuzumab, cisplatin, 5-FU (HCF) with the triplet regimens ECX, EOX and ECF, based on a simple, three-state cohort model (progression-free, disease, progression and death), was submitted. Utility weights were applied to estimate quality-adjusted life-years (QALYs). Costs were assessed from an NHS perspective, and incorporated the acquisition and monitoring costs of the alternative regimens, HER2 testing, adverse events and other supportive care costs. An 8-year time horizon was used to represent a lifetime analysis. Results from the ToGA trial were combined with a series of assumptions on relative treatment effects and testing strategies. The manufacturer’s results produced an incremental cost-effectiveness ratio (ICER) of £53,010 per QALY for HCX versus ECX. Although the manufacturer undertook a detailed set of sensitivity analyses, several alternative model assumptions were not evaluated. The ERG undertook a series of alternative base-case analyses. As a result of these analyses, EOX replaced ECX as the appropriate comparator, and the ICER for the comparison of HCX vs EOX increased to between £66,982 and £71,636 per QALY. The impact of implementation of alternative testing strategies remained unclear. There is also considerable uncertainty surrounding the true estimate of effectiveness for the comparison between triplet regimens containing epirubicin (ECX/ECF/EOX) and doublet CX/F regimens. Consequently, the view of the ERG was that there is insufficient evidence on the efficacy of HCX/F compared with current NHS standard therapy for an ICER to be determined with any degree of certainty.

Capecitabine for the treatment of advanced gastric cancer

This paper presents a summary of the evidence review group (ERG) report into capecitabine for advanced gastric cancer (aGC). Capecitabine is an oral prodrug of 5-fluorouracil (5-FU). The decision problem addressed was the use of capecitabine (X) compared to 5-FU (F), in combination regimens with platinum agents [cisplatin (C) or oxaliplatin (O)] with or without epirubicin (E), in patients with inoperable aGC. Approximately 7000 new cases of gastric cancer are diagnosed in England and Wales every year. Of these, 80% are candidates for palliative chemotherapy and around 2900 receive such treatment. The standard UK practice for patients with aGC who are considered fit enough has consisted of a triplet regimen comprising intravenous 5-FU in combination with a platinum agent (capecitabine or oxaliplatin) and epirubicin. The manufacturer's submission (MS) focused on direct evidence from two phase III non-inferiority randomised controlled trials (RCTs), REAL-2 (Randomized ECF for Advanced and Locally advanced oesophagogastric cancer-2; n = 1002) and ML17032 (n = 316). REAL-2 randomised patients to four regimens (ECF, ECX, EOF and EOX) to compare 5-FU with capecitabine and cisplatin with oxaliplatin, whereas ML17032 compared CX with CF. Efficacy outcomes from these trials were pooled in an individual patient data (IPD) meta-analysis. Both RCTs demonstrated statistically significant non-inferiority of capecitabine on the outcome of overall survival (OS) assessed in the per-protocol population; equivalent results were also demonstrated for progression-free survival (PFS). The IPD meta-analysis found a statistically significant benefit in OS for capecitabine compared with 5-FU [unadjusted hazard ratio (HR): 0.87; 95% confidence interval (CI) 0.77 to 0.98, p = 0.027]. There was no evidence of a poorer safety profile for capecitabine overall, nor of any difference in quality of life (QoL) between the two fluoropyrimidines. The MS included a de novo economic evaluation based on a cost-minimisation analysis (CMA), where the costs of capecitabine-based regimens were compared with their equivalent 5-FU-based regimens in aGC. A time horizon of 5.5 cycles (each lasting for 21 days) was used in the base-case analysis, representing the duration of treatment. The results of the manufacturer's base-case analysis showed that capecitabine regimens are associated with mean net cost savings of 1620 pounds (ECX vs ECF), 1572 pounds (EOX vs EOF) and 4210 pounds (CX vs CF). The manufacturer failed to comment explicitly on the uncertainty around the estimates of efficacy and on the fact that the IPD meta-analysis suggests that capecitabine may actually be more effective on average. Further analyses exploring additional costs incurred by the UK NHS from extending survival duration showed that these are unlikely to have a material effect on conclusions. A full probabilistic analysis was not performed; however, the evidence explored by the MS and ERG is consistent in suggesting that capecitabine has a lower mean cost than 5-FU-based regimens. The submission was considered to contain convincing evidence of the non-inferiority of capecitabine to 5-FU on survival; this evidence was considered to be applicable to UK practice. Although some uncertainty remains, the ERG deemed CMA to be an appropriate framework with which to analyse this decision problem. Overall cost estimates for the CMA were generated appropriately and were robust to uncertainties regarding assumptions and sources. At the time of writing, the guidance document issued by NICE on 28 July 2010 states that capecitabine in combination with a platinum-based regimen is recommended for the first-line treatment of inoperable advanced gastric cancer.

Capecitabine for the treatment of advanced gastric cancer

This paper presents a summary of the evidence review group (ERG) report into capecitabine for advanced gastric cancer (aGC). Capecitabine is an oral prodrug of 5-fluorouracil (5-FU). The decision problem addressed was the use of capecitabine (X) compared to 5-FU (F), in combination regimens with platinum agents [cisplatin (C) or oxaliplatin (O)] with or without epirubicin (E), in patients with inoperable aGC. Approximately 7000 new cases of gastric cancer are diagnosed in England and Wales every year. Of these, 80% are candidates for palliative chemotherapy and around 2900 receive such treatment. The standard UK practice for patients with aGC who are considered fit enough has consisted of a triplet regimen comprising intravenous 5-FU in combination with a platinum agent (capecitabine or oxaliplatin) and epirubicin. The manufacturer’s submission (MS) focused on direct evidence from two phase III non-inferiority randomised controlled trials (RCTs), REAL-2 (Randomized ECF for Advanced and Locally advanced oesophagogastric cancer-2; n = 1002) and ML17032 (n = 316). REAL-2 randomised patients to four regimens (ECF, ECX, EOF and EOX) to compare 5-FU with capecitabine and cisplatin with oxaliplatin, whereas ML17032 compared CX with CF. Efficacy outcomes from these trials were pooled in an individual patient data (IPD) meta-analysis. Both RCTs demonstrated statistically significant non-inferiority of capecitabine on the outcome of overall survival (OS) assessed in the per-protocol population; equivalent results were also demonstrated for progression-free survival (PFS). The IPD meta-analysis found a statistically significant benefit in OS for capecitabine compared with 5-FU [unadjusted hazard ratio (HR): 0.87; 95% confidence interval (CI) 0.77 to 0.98, p = 0.027]. There was no evidence of a poorer safety profile for capecitabine overall, nor of any difference in quality of life (QoL) between the two fluoropyrimidines. The MS included a de novo economic evaluation based on a cost-minimisation analysis (CMA), where the costs of capecitabine-based regimens were compared with their equivalent 5-FU-based regimens in aGC. A time horizon of 5.5 cycles (each lasting for 21 days) was used in the base-case analysis, representing the duration of treatment. The results of the manufacturer’s base-case analysis showed that capecitabine regimens are associated with mean net cost savings of £1620 (ECX vs ECF), £1572 (EOX vs EOF) and £4210 (CX vs CF). The manufacturer failed to comment explicitly on the uncertainty around the estimates of efficacy and on the fact that the IPD meta-analysis suggests that capecitabine may actually be more effective on average. Further analyses exploring additional costs incurred by the UK NHS from extending survival duration showed that these are unlikely to have a material effect on conclusions. A full probabilistic analysis was not performed; however, the evidence explored by the MS and ERG is consistent in suggesting that capecitabine has a lower mean cost than 5-FU-based regimens. The submission was considered to contain convincing evidence of the non-inferiority of capecitabine to 5-FU on survival; this evidence was considered to be applicable to UK practice. Although some uncertainty remains, the ERG deemed CMA to be an appropriate framework with which to analyse this decision problem. Overall cost estimates for the CMA were generated appropriately and were robust to uncertainties regarding assumptions and sources. At the time of writing, the guidance document issued by NICE on 28 July 2010 states that capecitabine in combination with a platinum-based regimen is recommended for the first-line treatment of inoperable advanced gastric cancer.

Association of UCP1 genetic polymorphisms with blood pressure among Korean female subjects

Recent studies have provided some clues with regard to the relationship existing between uncoupling protein 1 (UCP1) and blood pressure in animal experiments. In an attempt to determine the genetic polymorphisms that are associated with blood pressure in humans, we have analyzed genetic polymorphisms in UCP1 gene. In this study, we assessed the association between UCP1 genotypes and systolic blood pressure (SBP) and diastolic blood pressure (DBP), in a population comprised of 832 Korean female subjects, using a general linear model, which was adjusted for age and body mass index (BMI). Among 4 genetic polymorphisms and the haplotypes constructed from them, haplotype3 of UCP1, UCP1-ht3[GAGA], evidenced significant associations with SBP (p=0.005) and DBP (p=0.013). However, this haplotype was not significantly associated with obesity phenotypes, including BMI or fat mass (p>0.05), thereby suggesting that its association with blood pressure was independent of obesity phenotypes.

Effects of genetic polymorphism of uncoupling protein 2 on body fat and calorie restriction-induced changes

The purpose of this study is to estimate the effects of Ala55Val genetic polymorphism of uncoupling protein 2 on computed tomography-measured body fat area and calorie restriction-induced changes. Among 386 Korean female subjects, the AlaAla type was seen in 30.3%, the AlaVal type was seen in 47.2%, and the ValVal type was seen in 22.5%. This finding was in agreement with Hardy-Weinberg equilibrium. The frequency of the major Ala allele was 0.54, and that of the minor Val allele was 0.46, which were similar to those seen in Caucasian populations. When cross-sectional areas of fat tissues in the subjects were measured by computed tomography, it was shown that the total abdominal fat area and abdominal subcutaneous fat area were significantly smaller in the ValVal type compared with the AlaVal or AlaAla type (p=0.043 and p=0.044, respectively). The Ala55Val polymorphism had no effects on visceral fat area and thigh subcutaneous fat area. Among the 386 subjects, 236 subjects finished the 1-month calorie restriction program. The results showed that the body fat was reduced significantly less in the ValVal type compared with the other types (p=0.016), whereas the changes in lean body mass, protein, mineral, and water contents were not significantly different according to the Ala55Val polymorphism.

Low molecular weight polyethylenimine for efficient transfection of human hematopoietic and umbilical cord blood-derived CD34+ cells

With the emerging role of hematopoietic stem cells as potential gene and cell therapy vehicles, there is an increasing need for safe and effective nonviral gene delivery systems. Here, we report that gene transfer and transfection efficiency in human hematopoietic and cord blood CD34+ cells can be enhanced by the use of low molecular weight polyethylenimine (PEI). PEIs of various molecular weights (800-750,000) were tested, and our results showed that the uptake of plasmid DNA by hematopoietic TF-1 cells depended on the molecular weights and the N/P ratios. Treatment with PEI 2K (m.w. 2000) at an N/P ratio of 80/1 was most effective, increasing the uptake of plasmid DNA in TF-1 cells by 23-fold relative to Lipofectamine 2000. PEI 2K-enhanced transfection was similarly observed in hematopoietic K562, murine Sca-1+, and human cord blood CD34+ cells. Notably, in human CD34+ cells, a model gene transferred with PEI 2K showed 21,043- and 513-fold higher mRNA expression levels relative to the same construct transfected without PEI or with PEI 25 K, respectively. Moreover, PEI 2K-treated TF-1 and human CD34+ cells retained good viability. Collectively, these results indicate that PEI 2K at the optimal N/P ratio might be used to safely enhance gene delivery and transfection of hematopoietic and human CD34+ stem cells.

Plasmid vectors harboring cellular promoters can induce prolonged gene expression in hematopoietic and mesenchymal progenitor cells

Although prolonged transgene expression in progenitor cells might be desirable for modified cell therapy, the viral promoter-based expression vector tends to promote transgene expression only for a limited period. Here, we examined the ability of cellular promoters from elongation factor-1alpha (EF-1alpha) and ubiquitin C to drive gene expression in hematopoietic TF-1 and mesenchymal progenitor cells. We compared the expression levels and duration of a model gene, interleukin-2, generated by the cellular promoters to those by the cytomegalovirus (CMV) promoter. The EF-1alpha and ubiquitin C promoters drove prolonged gene expression in hematopoietic TF-1 and mesenchymal progenitor cells, whereas the CMV promoter did not. At day 7 after transfection in TF-1 cells, the mRNA expression levels of interleukin-2 driven by the EF-1alpha and ubiquitin C promoters were 118- and 56-fold higher, respectively, than those driven by the CMV promoter. Similarly, in mesenchymal progenitor cells, the expression levels of interleukin-2 driven by the EF-1alpha and ubiquitin C promoters were 98- and 20-fold higher, respectively, than that driven by the CMV promoter-encoding plasmid. Moreover, the ubiquitin C promoter directed higher levels of green fluorescence protein expression in mesenchymal progenitor cells than did the CMV promoter. These results indicate that the use of cellular promoters such as those for EF-1alpha and ubiquitin C might direct prolonged gene expression in hematopoietic and mesenchymal progenitor cells.

A DNA repair gene of Caenorhabditis elegans: a homolog of human XPF

The xeroderma pigmentosum complementation group F (XPF) protein is a structure-specific endonuclease in a complex with ERCC1 and is essential for nucleotide excision repair (NER). We report a single cDNA of Caenorhabditis elegans (C. elegans) encoding highly similar protein to human XPF and other XPF members. We propose to name the corresponding C. elegans gene xpf. Messenger RNA for C. elegans xpf is 5'-tagged with a SL2 splice leader, suggesting an operon-like expression for xpf. Using RNAi, we showed that loss of C. elegans xpf function caused hypersensitivity to ultra-violet (UV) irradiation, as observed in enhanced germ cell apoptosis and increased embryonic lethality. This study suggests that C. elegans xpf is conserved in evolution and plays a role in the repair of UV-damaged DNA in C. elegans.