The association between serum vitamin D level and risk and prognosis of melanoma: a systematic review and meta-analysis.

BACKGROUND: Vitamin D has antineoplastic effects, but the synthesis of vitamin D requires ultraviolet radiation, a known risk factor for melanoma. OBJECTIVE: To investigate the correlations between serum vitamin D levels and risk and prognosis of melanoma. METHODS: A systematic review and meta-analysis were conducted. Online databases were searched on 31 Oct 2018. RESULTS: Twenty-five studies with a total of 11166 patients with melanoma were included. There was no significant difference in serum vitamin D levels between patients with melanoma and controls [standardized mean difference (SMD), -0.185; 95% confidence interval (CI), -0.533 to 0.162]. However, the prevalence of vitamin D deficiency was significantly higher in patients with melanoma than that in controls (odds ratio, 2.115; 95% CI, 1.151-3.885). In terms of prognosis, serum vitamin D levels were significantly higher in melanoma patients with lower Breslow thickness (≦1 vs. >1 mm: SMD, 0.243; 95% CI, 0.160-0.327). Moreover, melanoma patients with lower vitamin D levels had a significantly higher mortality rate (hazard ratio, 1.558; 95% CI, 1.258-1.931). CONCLUSIONS: Vitamin D deficiency is associated with higher Breslow thickness and mortality in melanoma patients.

Melt processing of polypropylene-grafted-maleic anhydride/Chitosan polymer blend functionalized with montmorillonite for the removal of lead ions from aqueous solutions.

Heavy metals such as lead ions Pb (II) are a primary concern in the aquatic environment. These is because Pb (II) is poisonous at a threshold limit above 0.01 mg/L, when consumed over a long period of time. Pb (II) poisoning is very harmful to various organs viz. heart, intestine and kidneys. Besides, it affects bones, tissues, nervous and reproductive systems. Hence, it is important to remove Pb (II) from aquatic environment. Polypropylene (PP) and polypropylene grafted-maleic-anhydride (PP-g-MA) based nanocomposites reinforced with Chitosan (CS) and modified montmorillonite clay nanofiller (CL120DT) were successfully fabricated using twin screw melt extrusion for adsorption of Pb (II). The resulting nanocomposites were characterized by XRD to analyze the dispersion properties of the material, TEM and SEM for surface morphology, FTIR analysis for the functional groups and TGA for thermal stability. Pure PP showed two sharp peaks, but there was decreased in the intensity upon adding of CS and CL120DT. Among series of nanocomposites 2.0 phr and 4.0 phr loaded samples shows better storage module than that of pure PP. The uptake of Pb (II) from lead nitrate aqueous solution by PP + PP-g-MA/CL120DT-CS 2.0 phr nanocomposites followed the Langmuir isotherm model, with a remediation of 90.9% at pH 8 and was verified by pseudo-second order kinetic model. These results indicate that PP + PP-g-MA//CL120DT-CS 2.0 phr nanocomposites performed as a superabsorbent for the Pb (II) ion removal from aqueous solution.

Association of use of Chinese herbal medicines and the risk of fracture in patients with osteoporosis: a population-based cohort study.

After utilizing a large population-based claims database and the application of propensity score match approach to reduce the confounding effects, we found that the use of Chinese herbal medicines (CHMs) was related to the lower risk of sequent osteoporotic fracture by 27% among the individuals with osteoporosis. The predominant effect was observed in those receiving CHMs for more than two years. INTRODUCTION: Osteoporosis (OS) is a highly disabling condition that can lead to fragility fracture, thus posing greater burdens of functional limitations for the affected individuals. It is unclear if the use of Chinese herbal medicines (CHMs) could reduce the risk of fracture due to OS. This study aimed to investigate the association of CHMs and the subsequent osteoporotic fracture risk among OS patients. METHODS: This longitudinal cohort study used the Taiwanese National Health Insurance Research Database to identify 250,699 newly diagnosed OS patients aged 20 years or older between 1998 and 2010. We recruited 103,325 CHM users following the onset of OS (CHM users) and randomly selected 103,325 subjects without CHM usage as controls (non-CHM users) by propensity score matching according to the demographic characteristics and comorbidities at enrollment. All enrollees were followed until the end of 2012 to record the incidence of osteoporotic fracture. We applied the Cox proportional hazard regression model to compute the hazard ratio (HR) of the risk of osteoporotic fracture. RESULTS: During the 15-year follow-up period, 7208 CHM users and 11,453 non-CHM users sustained osteoporotic fracture, with an incidence rate of 9.26 and 12.96, respectively, per 1000 person-years. We found that CHM users had a significantly reduced risk of osteoporotic fracture compared to non-CHM users (adjusted HR 0.73; 95% confidence interval [CI] = 0.70-0.75). Those treated with CHMs for longer than 730 days had a lower fracture risk by 54%. Some commonly used CHMs, such as Yan hu suo (Rhizoma Corydalis), Huang Qin (Scutellaria Baicale), Jie Geng (Platycodon grandifloras), Xiang Fu (Cyperus rotundus), Hai Piao Xiao (Cuttlebone Sepium), Jia-Wei-Xiao-Yao-San, Ge-Gen-Tang, Shao-Yao-Gan-Cao-Tang, and Du-Huo-Ji-Sheng-Tang, are related to the lower risk of fracture. CONCLUSIONS: The use of CHMs was associated with lower risk of osteoporotic fracture for OS patients, suggesting that it could be integrated into conventional therapy to prevent subsequent bone fracture.

Serum homocysteine, folate and vitamin B12 levels in patients with psoriasis: a systematic review and meta-analysis.

BACKGROUND: Patients with psoriasis are at increased risk for cardiovascular comorbidities. Previous studies examined the possible contribution of serum homocysteine, folate and vitamin B12 to cardiovascular risks in patients with psoriasis but had conflicting conclusions. OBJECTIVES: To perform a systematic review and meta-analysis of studies on serum homocysteine, folate and vitamin B12 levels in patients with psoriasis. METHODS: Online databases were searched on 15 February 2018 to include studies comparing serum homocysteine, folate and vitamin B12 levels between patients with psoriasis and controls. A random effects model was adopted to estimate odds ratios for dichotomous data and standardized mean differences (SMDs) for continuous data. RESULTS: A comprehensive literature search identified 24 studies eligible for inclusion. Compared with controls, patients with psoriasis had a significantly higher serum homocysteine level [SMD 0·41, 95% confidence interval (CI) 0·21-0·61; I2 = 76·7%, 18 studies], a higher prevalence of hyperhomocysteinaemia (odds ratio 3·48, 95% CI 2·08-5·83; I2 = 41·1%, seven studies) and a lower serum folate level (SMD -0·94, 95% CI -1·49 to -0·40; I2 = 95·6%, 14 studies). However, there was no difference in serum vitamin B12 levels between patients with psoriasis and the control group (SMD 0·004, 95% CI -0·49 to 0·50; I2 = 92%, 11 studies). Metaregression analysis revealed a significant inverse correlation between the SMD of homocysteine levels and folate levels. CONCLUSIONS: Patients with psoriasis might have higher serum homocysteine and lower folate levels than control patients without psoriasis. However, due to significant heterogeneity and other limitations, the associations require further examinations in more studies.

Association of use of rehabilitation services with development of osteoporosis among patients with rheumatoid arthritis: a nationwide population-based cohort study.

This is the first study that has found that rehabilitation services (RS) intervention, following the onset of rheumatoid arthritis (RA), may significantly reduce the risk of osteoporosis in RA patients. Those patients who received more than five sessions of RS had the greatest benefit for the prevention of osteoporosis. INTRODUCTION: People with rheumatoid arthritis have increased risk of developing osteoporosis (OP). It remains unclear whether use of rehabilitation services can reduce the risk of developing OP. We conducted a longitudinal cohort study to compare the effect of RS on the risk of OP in Taiwanese individuals with RA. METHODS: A national health insurance database was used to identify 2693 newly diagnosed RA patients, 20-70 years old, between 1998 and 2007. Among them, 808 received RS after the onset of RA (RS users) and 1885 patients did not receive RS (non-RS users). All enrollees were followed until the end of 2012 to record incident cases of OP. A Cox proportional hazards regression model was used to compute adjusted hazard ratios (aHRs) for the relationship of use of RS with OP. RESULTS: During the 15-year follow-up, 358 RS users and 1238 non-RS users developed OP, corresponding to incidence rates of 87.24 and 129.27 per 1000 person-years, respectively. Use of RS was significantly associated with a lower risk of OP (aHR 0.62; 95% confidence interval [CI] = 0.56-0.71). Those who received more than five sessions of RS had the greatest benefit (aHR 0.47; 95% CI = 0.38-0.56). CONCLUSIONS: The integration of RS into the clinical management of patients with RA may decrease their risk of developing OP.

Side-to-side variation in normal femoral morphology: 3D CT analysis of 122 femurs.

BACKGROUND: The contralateral femur is often used as reference for reconstruction in unilateral hip joint pathology. The objective of this study was to quantify the side-to-side variation in proximal femur. We hypothesized that significant side-to-side differences exist between left and right femur with implications for preoperative planning and leg length discrepancy following hip arthroplasty. MATERIALS AND METHODS: CT-based 3D femoral models were reconstructed for 122 paired femurs in 61 young healthy subjects (46.9±6.8 years) with no history of hip pathology. Side-to-side differences of several femoral morphologic parameters, including femoral head diameter, femoral anteversion, horizontal offset and femoral head center location, were compared and correlated with demographic factors using multiple linear regression. RESULTS: Significant side-to-side differences (P<0.01) were found in femoral anteversion (4.3±3.8°; range: 0.2° to 17.3°), horizontal offset (2.5±2.1mm; range: 0.1 to 10.3mm), and femoral head center location (7.1±3.8mm; range: 0.5 to 19.4mm). The difference in femoral anteversion was strongly correlated with the difference in neck diameter (R(2)=0.79), whereas the difference in horizontal femoral offset was highly correlated with the head diameter difference (R(2)=0.72). Femoral head center difference was correlated with the femoral anteversion, horizontal offset and neck-shaft-angle difference (R(2)=0.82). DISCUSSION: Relying on the anatomic landmarks of the contralateral femur during hip arthroplasty may not necessarily result in restoration of native anatomy and leg-length. Knowledge of the baseline side-to-side asymmetry could provide a range of error that would be tolerable following hip reconstruction. LEVEL OF EVIDENCE: Level IV. TYPE OF STUDY: Retrospective observational study.

Cytotoxicity and antibacterial activity of gold-supported cerium oxide nanoparticles.

BACKGROUND: Cerium oxide nanoparticles (CeO2) have been shown to be a novel therapeutic in many biomedical applications. Gold (Au) nanoparticles have also attracted widespread interest due to their chemical stability and unique optical properties. Thus, decorating Au on CeO2 nanoparticles would have potential for exploitation in the biomedical field. METHODS: In the present work, CeO2 nanoparticles synthesized by a chemical combustion method were supported with 3.5% Au (Au/CeO2) by a deposition-precipitation method. The as-synthesized Au, CeO2, and Au/CeO2 nanoparticles were evaluated for antibacterial activity and cytotoxicity in RAW 264.7 normal cells and A549 lung cancer cells. RESULTS: The as-synthesized nanoparticles were characterized by X-ray diffraction, scanning and transmission electron microscopy, and ultraviolet-visible measurements. The X-ray diffraction study confirmed the formation of cubic fluorite-structured CeO2 nanoparticles with a size of 10 nm. All synthesized nanoparticles were nontoxic towards RAW 264.7 cells at doses of 0-1,000 µM except for Au at >100 µM. For A549 cancer cells, Au/CeO2 had the highest inhibitory effect, followed by both Au and CeO2 which showed a similar effect at 500 and 1,000 µM. Initial binding of nanoparticles occurred through localized positively charged sites in A549 cells as shown by a shift in zeta potential from positive to negative after 24 hours of incubation. A dose-dependent elevation in reactive oxygen species indicated that the pro-oxidant activity of the nanoparticles was responsible for their cytotoxicity towards A549 cells. In addition, cellular uptake seen on transmission electron microscopic images indicated predominant localization of nanoparticles in the cytoplasmic matrix and mitochondrial damage due to oxidative stress. With regard to antibacterial activity, both types of nanoparticles had the strongest inhibitory effect on Bacillus subtilis in monoculture systems, followed by Salmonella enteritidis, Escherichia coli, and Staphylococcus aureus, while, in coculture tests with Lactobacillus plantarum, S. aureus was inhibited to a greater extent than the other bacteria. CONCLUSION: Gold-supported CeO2 nanoparticles may be a potential nanomaterial for in vivo application owing to their biocompatible and antibacterial properties.

The synthesis and characterization of poly(γ-glutamic acid)-coated magnetite nanoparticles and their effects on antibacterial activity and cytotoxicity.

Magnetite nanoparticles (MNPs) modified with sodium and calcium salts of poly(γ-glutamic acid) (NaPGA and CaPGA) were synthesized by the coprecipitation method, followed by characterization and evaluation of their antibacterial and cytotoxic effects. Superparamagnetic MNPs are particularly attractive for magnetic driving as well as bacterial biofilm and cell targeting in in vivo applications. Characterization of synthesized MNPs by the Fourier transform infrared spectra and magnetization curves confirmed the PGA coating on MNPs. The mean diameter of NaPGA- and CaPGA-coated MNPs as determined by transmission electron microscopy was 11.8 and 14 nm, respectively, while the x-ray diffraction pattern revealed the as-synthesized MNPs to be pure magnetite. Based on agar dilution assay, both NaPGA- and CaPGA-coated MNPs showed a lower minimum inhibitory concentration in Salmonella enteritidis SE 01 than the commercial antibiotics linezolid and cefaclor, but the former was effective against Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 10832, whereas the latter was effective against Escherichia coli O157:H7 TWC 01. An in vitro cytotoxicity study in human skin fibroblast cells as measured by MTT assay implied the as-synthesized MNPs to be nontoxic. This outcome demonstrated that both γ-PGA-modified MNPs are cytocompatible and possess antibacterial activity in vitro, and thereby should be useful in in vivo studies for biomedical applications.

Candidate tumor suppressor DDX3 RNA helicase specifically represses cap-dependent translation by acting as an eIF4E inhibitory protein.

DDX3 is a human RNA helicase with plethoric functions. Our previous studies have indicated that DDX3 is a transcriptional regulator and functions as a tumor suppressor. In this study, we use a bicistronic reporter to demonstrate that DDX3 specifically represses cap-dependent translation but enhances hepatitis C virus internal ribosome entry site-mediated translation in vivo in a helicase activity-independent manner. To elucidate how DDX3 modulates translation, we identified translation initiation factor eukaryotic initiation factor 4E (eIF4E) as a DDX3-binding partner. Interestingly, DDX3 utilizes a consensus eIF4E-binding sequence YIPPHLR to interact with the functionally important dorsal surface of eIF4E in a similar manner to other eIF4E-binding proteins. Furthermore, cap affinity chromatography analysis suggests that DDX3 traps eIF4E in a translationally inactive complex by blocking interaction with eIF4G. Point mutations within the consensus eIF4E-binding motif in DDX3 impair its ability to bind eIF4E and result in a loss of DDX3's regulatory effects on translation. All these features together indicate that DDX3 is a new member of the eIF4E inhibitory proteins involved in translation initiation regulation. Most importantly, this DDX3-mediated translation regulation also confers the tumor suppressor function on DDX3. Altogether, this study demonstrates regulatory roles and action mechanisms for DDX3 in translation, cell growth and likely viral replication.

Enhanced biodegradation of petrochemical wastewater using ozonation and BAC advanced treatment system.

The characteristics of degradation/conversion of bio-refractory and the growth of a biofilm are investigated in laboratory-scale pre-ozonation and lifted moving-bed biological activated carbon (BAC) advanced treatment processes treating phenol, benzoic acid, aminobenzoic acid and petrochemical industry wastewater which contains acrylonitrile butadiene styrene (ABS). The optimal reaction time and ozone dosage of pre-ozonation for bio-refractory conversion were determined to be 30 min and 100-200 mg O3/hr, respectively. After pre-ozonation of 30 min treatment, BOD5/COD ratio of influent and effluent increased apparently from 20 to 35%, approximately. However, the change of pH in pre-ozonation was inconspicuous. The optimal flow rate of influent and air were controlled at 1.6 l/h and 120-150 nl/min in lifted moving-bed BAC advanced treatment reactor. A COD removal efficiency of 85-95% and 70-90% may be maintained by using an organic loading of 3.2-6.3 kg COD/m3 day and 0.6-1.6 kg-COD/m3 day with an HRT of 6.0 h as secondary and advanced treatment system, respectively. The time required for the BAC bed is be regenerated by a thermal regeneration is prolonged 4-5 times more than that of GAC system. It can be estimated that the enhanced COD removal capability of the biofilm was not only due to the increase in the COD removal capability of acclimated bacteria, but also due to species succession of bacteria in bio-film ecosystem.

The clinical use of small-dose tetracaine spinal anesthesia for transurethral prostatectomy.

UNLABELLED: In a double-blinded study, we compared conventional dose tetracaine (8 mg), small-dose tetracaine (4 mg) with added fentanyl and epinephrine, and small-dose tetracaine (4 mg) with added fentanyl subarachnoid anesthesia. Forty-five patients scheduled for transurethral resection of prostate (TURP) under subarachnoid anesthesia were randomly assigned to Group 1 (8 mg hyperbaric tetracaine), Group 2 (4 mg hyperbaric tetracaine, 10 microg fen-tanyl, and 0.2 mg epinephrine), and Group 3 (4 mg hyperbaric tetracaine, 10 microg fentanyl, and 0.2 mL saline). Evaluations were performed after spinal anesthesia. Subarachnoid block was successful in all patients except one in Group 1, who required general anesthesia by mask. The median peak sensory levels 10 min after the induction of spinal anesthesia in Group 1 was T8, which was significantly higher than Group 2 and Group 3 (P < 0.05). The time of sensory and motor recovery in Group 3 was less than in Groups 1 and 2 (P < 0.05). Hypotension was observed in four patients in Group 1 and none in Groups 2 and 3. We conclude that small-dose 4-mg hyperbaric tetracaine plus 10 microg fentanyl might provide adequate anesthesia and fewer side effects for TURP when compared with the conventional (8 mg) dose. IMPLICATIONS: Small-dose hyperbaric tetracaine (4 mg with 10 microg fentanyl added) may provide adequate anesthesia and fewer side effects for transurethral resection of the prostate.

Q-switched 2-micron lasers by use of a Cr2+:ZnSe saturable absorber.

Flash-lamp-pumped Ho:YAG (2090-nm) and Tm:YAG (2017-nm) lasers were, for the first time to our knowledge, passively Q switched by use of a Cr2+:ZnSe saturable absorber. A Q-switched Ho laser with 1.3-mJ pulse energy and approximately 90-ns pulse duration and a Q-switched Tm laser with approximately 3.2-mJ pulse energy and 90-ns pulse duration were demonstrated. Compared with the free-running output energies at the Q-switching threshold pump levels, the Q-switching efficiencies were approximately 5% for the Ho:YAG laser and 16% for the Tm:YAG laser.

Degradation of repaired denture base materials in simulated oral fluid.

This in vitro study evaluates the degradation of repaired denture bases upon immersion in a simulated oral fluid. Denture base materials (Luciton 199), after being repaired by Repair Material and Triad, using three different joint surface designs (butt, round and 45 degrees bevel), were immersed onto 99.5 vol.% ethanol/water solution (with similar solubility parameter) for various amounts of time (0-72 h). The flexural loads of the six combination of groups were measured by the three-point bending tests using a universal testing machine. Acoustic emission (AE) during sample fracturing were processed using the MISTRA 2001 system. The fracture pattern and surface details of the interface were examined with a scanning electronic microscope (SEM). Data were analysed using three-way ANOVA and Tukey LSD tests. SEM micrographs of the fracture interface were used to differentiate the fracture mode. The flexural loads (2.72 +/- 0.51 Kgf) of the round joint specimens were significantly higher (P< 0.05) than those (butt: 1.66 +/- 0.38 Kgf, 45 degrees bevel: 1.93 +/- 0.41 Kgf) of the other two designs. This corresponds to the microscopic examination in which more cohesive failure mode was found for the round joint group after storage. The flexural loads (2.54 +/- 0.39 Kgf) of the specimens repaired with Triad were significantly higher (P < 0.05) than those (1.59 +/- 0.40 Kgf) of specimens repaired with Repair Material. Significant progressive reduction of the flexural load and/or AE signals of the specimens was noted in proportion to the length of time of the immersion in the simulated oral fluid. Mechanical strength of a denture base repaired with a round joint design and light-cured material is significantly higher after immersion in simulated oral fluid.

Essential role of mitogen-activated protein kinase pathway and c-Jun induction in epidermal growth factor-induced gene expression of human 12-lipoxygenase.

The role of mitogen-activated protein kinase signaling and the transcription factor c-Jun in epidermal growth factor (EGF)-induced expression of 12-lipoxygenase in human epidermoid carcinoma A431 cells was studied. EGF increased the activation of extracellular signal-regulated kinase (ERK) and c-Jun amino terminal kinase (JNK) in a time-dependent manner. Treatment of the cells with an mitogen-activated protein kinase kinase inhibitor, PD098059 (30 microM), inhibited the EGF- and pSV2ras-induced expression of 12-lipoxygenase mRNA. Transfection of the cells with Ras, ERK2, Rac, JNK dominant negative mutants pMMrasDN, K52R ERK2, RacN17, and mJNK all inhibited the EGF-induced promoter activation of the 12-lipoxygenase gene. EGF induced the expression of c-Jun and the activity of transcription factor activator protein 1 in cells, and these effects were blocked by the treatment with K52R ERK2 and mJNK. Overexpression of c-Jun increased the expression of 12-lipoxygenase mRNA and enzyme activity. Furthermore, the Sp1-binding sites in the promoter region of the 12-lipoxygenase gene were requisite for c-Jun response, which was similar to that previously observed in EGF response. The results indicate that the EGF-induced expression of 12-lipoxygenase in A431 cells was mediated through the Ras-ERK and Ras-Rac-JNK signal pathways. Subsequent induction of c-Jun led by ERK and JNK activation was essential for this EGF response.

Effects of chronic treatment with (+)-nicotine on the stress-induced hypertension and downregulation of central nicotinic receptors in rats: comparative study with (-)-nicotine.

The effects of chronic treatment with (+)-nicotine on the immobilization stress-induced changes in blood pressure, body weight, and [3H]cytisine binding to brain nicotinic receptors were examined in rats and were compared with those of (-)-nicotine. Immobilization stress (2 hr/day(-1), for 2 weeks) induced a moderate elevation of blood pressure, loss of body weight gain, and downregulation of [3H]cytisine binding sites in cerebral cortex and midbrain. Chronic treatment with (+)- or (-)-nicotine inhibited the stress-induced hypertension but did not suppress the inhibition of body weight gain by stress. Body weight before stress load was also reduced by (-)-nicotine but not (+)-nicotine treatment. Treatment with each isomer increased the maximum number of [3H]cytisine binding sites (Bmax) of brain stem, cerebral cortex, and hippocampus. The Bmax in midbrain was also increased by (+)-nicotine but not by (-)-nicotine. Stress-induced downregulation in cerebral cortex was inhibited by both isomers. These results suggest that (+)- and (-)-nicotine cause various effects, including anti-stress effect, on the central nervous system in rats, which are slightly different between the isomers.

Hepatitis C virus core protein interacts with cellular putative RNA helicase.

The nucleocapsid core protein of hepatitis C virus (HCV) has been shown to trans-act on several viral or cellular promoters. To get insight into the trans-action mechanism of HCV core protein, a yeast two-hybrid cloning system was used for identification of core protein-interacting cellular protein. One such cDNA clone encoding the DEAD box family of putative RNA helicase was obtained. This cellular putative RNA helicase, designated CAP-Rf, exhibits more than 95% amino acid sequence identity to other known RNA helicases including human DBX and DBY, mouse mDEAD3, and PL10, a family of proteins generally involved in translation, splicing, development, or cell growth. In vitro binding or in vivo coimmunoprecipitation studies demonstrated the direct interaction of the full-length/matured form and C-terminally truncated variants of HCV core protein with this targeted protein. Additionally, the protein's interaction domains were delineated at the N-terminal 40-amino-acid segment of the HCV core protein and the C-terminal tail of CAP-Rf, which encompassed its RNA-binding and ATP hydrolysis domains. Immunoblotting or indirect immunofluorescence analysis revealed that the endogenous CAP-Rf was mainly localized in the nucleus and to a lesser extent in the cytoplasm, and when fused with FLAG tag, it colocalized with the HCV core protein either in the cytoplasm or in the nucleus. Similar to other RNA helicases, this cellular RNA helicase has nucleoside triphosphatase-deoxynucleoside triphosphatase activity, but this activity is inhibited by various forms of homopolynucleotides and enhanced by the HCV core protein. Moreover, transient expression of HCV core protein in human hepatoma HuH-7 cells significantly potentiated the trans-activation effect of FLAG-tagged CAP-Rf or untagged CAP-Rf on the luciferase reporter plasmid activity. All together, our results indicate that CAP-Rf is involved in regulation of gene expression and that HCV core protein promotes the trans-activation ability of CAP-Rf, likely via the complex formation and the modulation of the ATPase-dATPase activity of CAP-Rf. These findings provide evidence that HCV may have evolved a distinct mechanism in alteration of host cellular gene expression regulation via the interaction of its nucleocapsid core protein and cellular putative RNA helicase known to participate in all aspects of cellular processes involving RNA metabolism. This feature of core protein may impart pleiotropic effects on host cells, which may partially account for its role in HCV pathogenesis.

Roles of copper ligands in the activation and secretion of Streptomyces tyrosinase.

The expression of the melanin operon (melC) of Streptomyces antibioticus requires the chaperone-like protein MelC1 for the incorporation of two copper ions (designated as CuA and CuB) and the secretion of the apotyrosinase (MelC2) via a transient binary complex formation between these two proteins. To investigate whether the copper ligand of tyrosinase is involved in this MelC1.MelC2 binary complex function, six single substitution mutations were introduced into the CuA and CuB sites. These mutations led to differential effects on the stability, copper content, and export function of binary complexes but a complete abolishment of tyrosinase activity. The defects in the tyrosinase activity in mutants were not because of the impairment of the formation of MelC1. MelC2 complex but rather the failure of MelC2 to be discharged from the copper-activated binary complex. Moreover, the impairments on the discharge of the mutant MelC2 from all the mutant binary complexes appeared to result from the structural changes in their apoforms or copper-activated forms of the complexes, as evidenced by the fluorescence emission and circular dichroism spectral analysis. Therefore, each of six copper ligands in Streptomyces tyrosinase binuclear copper sites plays a pivotal role in the final maturation and the discharge of tyrosinase from the binary complex but has a less significant role in its secretion.