Structural Similarities and Overlapping Activities among Dihydroflavonol 4-Reductase, Flavanone 4-Reductase, and Anthocyanidin Reductase Offer Metabolic Flexibility in the Flavonoid Pathway

Flavonoids are potent antioxidants that play a role in defense against pathogens, UV-radiation, and the detoxification of reactive oxygen species. Dihydroflavonol 4-reductase (DFR) and flavanone 4-reductase (FNR) reduce dihydroflavonols and flavanones, respectively, using NAD(P)H to produce flavan-(3)-4-(di)ols in flavonoid biosynthesis. Anthocyanidin reductase (ANR) reduces anthocyanidins to flavan-3-ols. In addition to their sequences, the 3D structures of recombinant DFR, FNR and ANR from sorghum and switchgrass showed a high level of similarity. The catalytic mechanism, substrate-specificity and key residues of three reductases were deduced from crystal structures, site-directed mutagenesis, molecular docking, kinetics, and thermodynamic ana-lyses. Although DFR displayed its highest activity against dihydroflavonols, it also showed activity against flavanones and anthocyanidins. It was inhibited by the flavonol quercetin and high concentrations of dihydroflavonols/flavonones. SbFNR1 and SbFNR2 did not show any activity against dihydroflavonols. However, SbFNR1 displayed activity against flavanones and ANR activity against two anthocyanidins, cyanidin and pelargonidin. Therefore, SbFNR1 and SbFNR2 could be specific ANR isozymes without delphinidin activity. Sorghum has high concentrations of 3-deoxyanthocyanidins in vivo, supporting the observed high activity of SbDFR against flavonols. Mining of expression data indicated substantial induction of these three reductase genes in both switchgrass and sorghum in response to biotic stress. Key signature sequences for proper DFR/ANR classification are proposed and could form the basis for future metabolic engineering of flavonoid metabolism.

A sorghum ascorbate peroxidase with four binding sites has activity against ascorbate and phenylpropanoids

In planta, H2O2 is produced as a by-product of enzymatic reactions and during defense responses. Ascorbate peroxidase (APX) is a key enzyme involved in scavenging cytotoxic H2O2. Here, we report the crystal structure of cytosolic APX from sorghum (Sorghum bicolor) (Sobic.001G410200). While the overall structure of SbAPX was similar to that of other APXs, SbAPX uniquely displayed four bound ascorbates rather than one. In addition to the ɣ-heme pocket identified in other APXs, ascorbates were bound at the δ-meso and two solvent-exposed pockets. Consistent with the presence of multiple binding sites, our results indicated that the H2O2-dependent oxidation of ascorbate displayed positive cooperativity. Bound ascorbate at two surface sites established an intricate proton network with ascorbate at the ɣ-heme edge and δ-meso sites. Based on crystal structures, steady-state kinetics, and site-directed mutagenesis results, both ascorbate molecules at the ɣ-heme edge and the one at the surface are expected to participate in the oxidation reaction. We provide evidence that the H2O2-dependent oxidation of ascorbate by APX produces a C2-hydrated bicyclic hemiketal form of dehydroascorbic acid at the ɣ-heme edge, indicating two successive electron transfers from a single-bound ascorbate. In addition, the δ-meso site was shared with several organic compounds, including p-coumaric acid and other phenylpropanoids, for the potential radicalization reaction. Site-directed mutagenesis of the critical residue at the ɣ-heme edge (R172A) only partially reduced polymerization activity. Thus, APX removes stress-generated H2O2 with ascorbates, and also uses this same H2O2 to potentially fortify cell walls via oxidative polymerization of phenylpropanoids in response to stress.

Activity of Cytosolic Ascorbate Peroxidase (APX) from Panicum virgatum against Ascorbate and Phenylpropanoids

APX is a key antioxidant enzyme in higher plants, scavenging H2O2 with ascorbate in several cellular compartments. Here, we report the crystal structures of cytosolic ascorbate peroxidase from switchgrass (Panicum virgatum L., Pvi), a strategic feedstock plant with several end uses. The overall structure of PviAPX was similar to the structures of other APX family members, with a bound ascorbate molecule at the ɣ-heme edge pocket as in other APXs. Our results indicated that the H2O2-dependent oxidation of ascorbate displayed positive cooperativity. Significantly, our study suggested that PviAPX can oxidize a broad range of phenylpropanoids with δ-meso site in a rather similar efficiency, which reflects its role in the fortification of cell walls in response to insect feeding. Based on detailed structural and kinetic analyses and molecular docking, as well as that of closely related APX enzymes, the critical residues in each substrate-binding site of PviAPX are proposed. Taken together, these observations shed new light on the function and catalysis of PviAPX, and potentially benefit efforts improve plant health and biomass quality in bioenergy and forage crops.

X-ray Crystallography: Seeding Technique with Cytochrome P450 Reductase

Cytochrome P450 reductase (CPR) is a multi-domain protein that acts as a redox partner of cytochrome P450s. The CPR contains a flavin adenine dinucleotide (FAD)-binding domain, a flavin mononucleotide (FMN)-binding domain, and a connecting domain. To achieve catalytic events, the FMN-binding domain needs to move relative to the FAD-binding domain, and this high flexibility complicates structural determination in high-resolution by X-ray crystallography. Here, we demonstrate a seeding technique of sorghum CPR crystals for resolution improvement, which can be applied to other poorly diffracting protein crystals. Protein expression is completed using an E. coli cell line with a high protein yield and purified using chromatography techniques. Crystals are screened using an automated 96-well plating robot. Poorly diffracting crystals are originally grown using a hanging drop method from successful trials observed in sitting drops. A macro seeding technique is applied by transferring crystal clusters to fresh conditions without nucleation to increase crystal size. Prior to diffraction, a dehydration technique is applied by serial transfer to higher precipitant concentrations. Thus, an increase in resolution by 7 Å is achieved by limiting the inopportune effects of the flexibility inherent to the domains of CPR, and secondary structures of SbCPR2c are observed. Graphical abstract.

Peptide Sequence Determines Structural Sensitivity to Supramolecular Polymerization Pathways and Bioactivity

Pathways in supramolecular polymerization traverse different regions of the system's energy landscape, affecting not only their architectures and internal structure but also their functions. We report here on the effects of pathway selection on polymerization for two isomeric peptide amphiphile monomers with amino acid sequences AAEE and AEAE. We subjected the monomers to five different pathways that varied in the order they were exposed to electrostatic screening by electrolytes and thermal annealing. We found that introducing electrostatic screening of E residues before annealing led to crystalline packing of AAEE monomers. Electrostatic screening decreased intermolecular repulsion among AAEE monomers thus promoting internal order within the supramolecular polymers, while subsequent annealing brought them closer to thermodynamic equilibrium with enhanced β-sheet secondary structure. In contrast, supramolecular polymerization of AEAE monomers was less pathway dependent, which we attribute to side-chain dimerization. Regardless of the pathway, the internal structure of AEAE nanostructures had limited internal order and moderate β-sheet structure. These supramolecular polymers generated hydrogels with lower porosity and greater bulk mechanical strength than those formed by the more cohesive AAEE polymers. The combination of dynamic, less ordered internal structure and bulk strength of AEAE networks promoted strong cell-material interactions in adherent epithelial-like cells, evidenced by increased cytoskeletal remodeling and cell spreading. The highly ordered AAEE nanostructures formed porous hydrogels with inferior bulk mechanical properties and weaker cell-material interactions. We conclude that pathway sensitivity in supramolecular synthesis, and therefore structure and function, is highly dependent on the nature of dominant interactions driving polymerization.

Characterization of Interactions between CTX-M-15 and Clavulanic Acid, Desfuroylceftiofur, Ceftiofur, Ampicillin, and Nitrocefin

Cefotaximase-Munich (CTX-M) extended-spectrum beta-lactamases (ESBLs) are commonly associated with Gram-negative, hospital-acquired infections worldwide. Several beta-lactamase inhibitors, such as clavulanate, are used to inhibit the activity of these enzymes. To understand the mechanism of CTX-M-15 activity, we have determined the crystal structures of CTX-M-15 in complex with two specific classes of beta-lactam compounds, desfuroylceftiofur (DFC) and ampicillin, and an inhibitor, clavulanic acid. The crystal structures revealed that Ser70 and five other residues (Lys73, Tyr105, Glu166, Ser130, and Ser237) participate in catalysis and binding of those compounds. Based on analysis of steady-state kinetics, thermodynamic data, and molecular docking to both wild-type and S70A mutant structures, we determined that CTX-M-15 has a similar affinity for all beta-lactam compounds (ceftiofur, nitrocefin, DFC, and ampicillin), but with lower affinity for clavulanic acid. A catalytic mechanism for tested β-lactams and two-step inhibition mechanism of clavulanic acid were proposed. CTX-M-15 showed a higher activity toward DFC and nitrocefin, but significantly lower activity toward ampicillin and ceftiofur. The interaction between CTX-M-15 and both ampicillin and ceftiofur displayed a higher entropic but lower enthalpic effect, compared with DFC and nitrocefin. DFC, a metabolite of ceftiofur, displayed lower entropy and higher enthalpy than ceftiofur. This finding suggests that compounds containing amine moiety (e.g., ampicillin) and the furfural moiety (e.g., ceftiofur) could hinder the hydrolytic activity of CTX-M-15.

Hydrogen Bonding Stiffens Peptide Amphiphile Supramolecular Filaments by Aza-Glycine Residues

Peptide amphiphiles (PAs) are a class of molecules comprised of short amino acid sequences conjugated to hydrophobic moieties that may exhibit self-assembly in water into supramolecular structures. We investigate here how mechanical properties of hydrogels formed by PA supramolecular nanofibers are affected by hydrogen bond densities within their internal structure by substituting glycine for aza-glycine (azaG) residues. We found that increasing the number of PA molecules that contain azaG up to 5 mol% in PA supramolecular nanofibers increases their persistence length fivefold and decreases their diffusion coefficients as measured by fluorescence recovery after photobleaching. When these PAs are used to create hydrogels, their bulk storage modulus (G') was found to increase as azaG PA content in the supramolecular assemblies increases up to a value of 10 mol% and beyond this value a decrease was observed, likely due to diminished levels of nanofiber entanglement in the hydrogels as a direct result of increased supramolecular rigidity. Interestingly, we found that the bioactivity of the scaffolds toward dopaminergic neurons derived from induced pluripotent stem cells can be enhanced directly by persistence length independently of storage modulus. We hypothesize that this is due to interactions between the cells and the extracellular environment across different size scales: from filopodia adhering to individual nanofiber bundles to cell adhesion sites that interact with the hydrogel as a bulk substrate. Fine tuning of hydrogen bond density in self-assembling peptide biomaterials such as PAs provides an approach to control nanoscale stiffness as part of an overall strategy to optimize bioactivity in these supramolecular systems. supramolecular biomaterials. STATEMENT OF SIGNIFICANCE: Hydrogen bonding is an important driving force for the self-assembly of peptides in both biological and artificial systems. Here, we increase the amount of hydrogen bonding within self-assembled peptide amphiphile (PA) nanofibers by substituting glycine for an aza-glycine (azaG). We show that increasing the molar concentration of azaG increases the internal order of individual nanofibers and increases their persistence length. We also show that these changes are sufficient to increase survival and tyrosine hydroxylase expression in induced pluripotent stem cell-derived dopaminergic neurons cultured in 3D gels made of these materials. Our strategy of tuning the number of hydrogen bonds in a supramolecular assembly provides mechanical customization for 3D cell culture and tissue engineering.

Growth Factor Delivery for the Repair of a Critical Size Tibia Defect Using an Acellular, Biodegradable Polyethylene Glycol-Albumin Hydrogel Implant

Growth factor delivery using acellular matrices presents a promising alternative to current treatment options for bone repair in critical-size injuries. However, supra-physiological doses of the factors can introduce safety concerns that must be alleviated, mainly by sustaining delivery of smaller doses using the matrix as a depot. We developed an acellular, biodegradable hydrogel implant composed of poly(ethylene glycol) (PEG) and denatured albumin to be used for sustained delivery of bone morphogenic protein-2 (BMP2). In this study, poly(ethylene glycol)-albumin (PEG-Alb) hydrogels were produced and loaded with 7.7 μg/mL of recombinant human BMP2 (rhBMP2) to be tested for safety and performance in a critical-size long-bone defect, using a rodent model. The hydrogels were formed ex situ in a 5 mm long cylindrical mold of 3 mm diameter, implanted into defects made in the tibia of Sprague-Dawley rats and compared to non-rhBMP2 control hydrogels at 13 weeks following surgery. The hydrogels were also compared to the more established PEG-fibrinogen (PEG-Fib) hydrogels we have tested previously. Comprehensive in vitro characterization as well as in vivo assessments that include: histological analyses, including safety parameters (i.e., local tolerance and toxicity), assessment of implant degradation, bone formation, as well as repair tissue density using quantitative microCT analysis were performed. The in vitro assessments demonstrated similarities between the mechanical and release properties of the PEG-Alb hydrogels to those of the PEG-Fib hydrogels. Safety analysis presented good local tolerance in the bone defects and no signs of toxicity. A significantly larger amount of bone was detected at 13 weeks in the rhBMP2-treated defects as compared to non-rhBMP2 defects. However, no significant differences were noted in bone formation at 13 weeks when comparing the PEG-Alb-treated defects to PEG-Fib-treated defects (with or without BMP2). The study concludes that hydrogel scaffolds made from PEG-Alb containing 7.7 μg/mL of rhBMP2 are effective in accelerating the bridging of boney defects in the tibia.

DNA-Peptide Amphiphile Nanofibers Enhance Aptamer Function

The single stranded DNA oligonucleotides known as aptamers have the capacity to bind proteins and other molecules and offer great therapeutic potential. Further work is required to optimize their function and to diminish their susceptibility to nuclease degradation. We report here on the synthesis and supramolecular self-assembly of DNA-peptide amphiphiles that form high aspect ratio nanofibers and display aptamers for platelet-derived growth factor. The nanofibers were found to bind the growth factor with an affinity that was fivefold greater than the free aptamer. We also observed that the aptamer displayed by the supramolecular nanostructures was eight times more nuclease resistant than free aptamer. In order to highlight the therapeutic potential of these supramolecular systems, we demonstrated the improved inhibition of proliferation when the growth factor was bound to aptamers displayed by the nanofibers.

Reversible self-assembly of superstructured networks

Soft structures in nature, such as protein assemblies, can organize reversibly into functional and often hierarchical architectures through noncovalent interactions. Molecularly encoding this dynamic capability in synthetic materials has remained an elusive goal. We report on hydrogels of peptide-DNA conjugates and peptides that organize into superstructures of intertwined filaments that disassemble upon the addition of molecules or changes in charge density. Experiments and simulations demonstrate that this response requires large-scale spatial redistribution of molecules directed by strong noncovalent interactions among them. Simulations also suggest that the chemically reversible structures can only occur within a limited range of supramolecular cohesive energies. Storage moduli of the hydrogels change reversibly as superstructures form and disappear, as does the phenotype of neural cells in contact with these materials.

Instructing cells with programmable peptide DNA hybrids

The native extracellular matrix is a space in which signals can be displayed dynamically and reversibly, positioned with nanoscale precision, and combined synergistically to control cell function. Here we describe a molecular system that can be programmed to control these three characteristics. In this approach we immobilize peptide-DNA (P-DNA) molecules on a surface through complementary DNA tethers directing cells to adhere and spread reversibly over multiple cycles. The DNA can also serve as a molecular ruler to control the distance-dependent synergy between two peptides. Finally, we use two orthogonal DNA handles to regulate two different bioactive signals, with the ability to independently up- or downregulate each over time. This enabled us to discover that neural stem cells, derived from the murine spinal cord and organized as neurospheres, can be triggered to migrate out in response to an exogenous signal but then regroup into a neurosphere as the signal is removed.

Tactic-specific benefits of polyandry in Chinook salmon Oncorhynchus tshawytscha

This study examined whether polyandrous female Chinook salmon Oncorhynchus tshawytscha obtain benefits compared with monandrous females through an increase in hatching success. Both of the alternative reproductive tactics present in male O. tshawytscha (large hooknoses and small, precocious jacks) were used, such that eggs were either fertilized by a single male (from each tactic) or multiple males (using two males from the same or different tactics). The results show that fertilized eggs from the polyandrous treatments had a significantly higher hatching success than those from the monandrous treatments. It is also shown that sperm speed was positively related with offspring hatching success. Finally, there were tactic-specific effects on the benefits females received. The inclusion of jacks in any cross resulted in offspring with higher hatching success, with the cross that involved a male from each tactic providing offspring with the highest hatching success than any other cross. This study has important implications for the evolution of multiple mating and why it is so prevalent across taxa, while also providing knowledge on the evolution of mating systems, specifically those with alternative reproductive tactics.

Chromosomal ampC mutations in cefpodoxime-resistant, ESBL-negative uropathogenic Escherichia coli

AmpC β-lactamase is an enzyme commonly produced by Escherichia coli that causes resistance to cephalosporins and penicillins. Enzyme production is controlled by the strength of the promoter encoded by the chromosomal ampC gene, with the level of production affected by the presence of certain mutations in this region. This study sets out to determine the prevalence of ampC promoter mutations present in a group of uropathogenic E. coli strains. A total of 50 clinical strains of E. coli were collected from urine samples between June 2011 and November 2011. Strains were investigated for the presence of mutations in the chromosomal ampC promoter region by amplification and sequencing of a 271 bp product. The presence of ampC-carrying plasmids derived from other species was also determined, to exclude these from further analysis. ampC-carrying plasmids were found in 10 of the 50 strains, all of which were of the CIT-type. Analysis of the chromosomal ampC promoter region in the 40 remaining strains showed mutations at 16 different positions, with 18 different genotype patterns detected overall. The most common ampC chromosomal mutation, present in 25 of 40 strains, was a T --> A transition at position -32. This mutation has been shown by others to increase enzyme production by up to 46-fold. Altogether, three separate mutations (-32, -42 and -13ins) were present in 90% of the 40 non-plasmid strains, indicating a strong association with the resistance observed. It appears, therefore, that the majority of AmpC-mediated resistance in E. coli can be accounted for by just three point mutations in the chromosome.

Intact globe inflation testing of changes in scleral mechanics in myopia and recovery

The purpose of this study was to examine the effects of myopia-inducing and myopia recovery conditions on the scleral biomechanics of enucleated eyes of young chicks. Enucleated eyes from 5-day old chicks, with fiducial markers attached at 5 locations on the external sclera, were placed in a custom-built chamber filled with phosphate-buffered saline, and subjected to controlled increments in intraocular pressure (IOP). IOP was initially ramped from 15 to 100 mmHg and then maintained at 100 mmHg for one hour, with eyes photographed at a rate of 0.1 Hz over the same period. There were two experimental groups, one in which chicks were monocularly form deprived for four days to induce myopia, and the other in which chicks were allowed two days of recovery from myopia induced by two days of form deprivation. For all chicks, the contralateral (fellow) eyes served as controls. Myopic eyes showed less initial deformation relative to their fellows, while no difference was recorded between recovering eyes and their fellows over the same time frame. With exposure to sustained elevated pressure, eyes in all groups displayed time-dependent changes in creep behavior, which included a linear region of secondary, steady creep. The creep deformation of myopic eyes was significantly higher than that of their fellows, consistent with results of previous studies using uniaxial loading of scleral strips. When allowed only 2 days to recover from induced myopia, previously myopic eyes continued to show increased creep deformation. Compared to results reported in studies involving scleral strips, our whole globe testing yielded higher values for creep rate. Whole globe inflation testing provides a viable, less anatomically disruptive and readily adaptable method for investigating scleral biomechanics than uniaxial tensile strip testing. Furthermore, our results suggest that elastic stretching does not contribute to the increased axial elongation underlying myopia in young chick eyes. They also confirm the very limited involvement of the sclera in the early recovery from myopia, reflecting the well documented lag in scleral versus choroidal recovery responses.

Epanolol as a Model for Assessing Patient Preference in Anti-Anginal Drug Therapy

Since drug therapy of angina is likely to produce a similar degree of efficacy for most drugs in common use, treatment choice should additionally focus on other factors, notably adverse events, quality of life, and convenience. Improvements in these factors can also lead to better compliance and can aid the doctor by cutting down the number of patient visits required to optimize therapy. The authors have evaluated the patient's overall assessment of symptomatic relief and adverse experiences in a comparative manner by means of the two-period crossover design using the patient's declared treatment preference as the primary measurement. This encapsulates several factors in a single assessment that can be understood by both physician and patient. The authors carried out two such studies of epanolol (Visacor), a novel anti-anginal agent with both beta-1 selective antagonist activity and also beta-1 selective partial agonist activity. In one study (n = 608) the comparator was metoprolol, and in the other (n = 571) it was nifedipine. This article describes and evaluates the methodology of these studies. To assess preference optimally, each patient had to receive both treatments in short but clinically relevant treatment periods, with no washout. Re-entry into the second period, after withdrawal from the first, was permitted. Both studies showed advantages for epanolol, more marked in the case of nifedipine, arising from equivalent efficacy but fewer adverse events.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumorigenicity assessments of Per.C6 cells and of an Ad5-vectored HIV-1 vaccine produced on this continuous cell line

PER.C6, a cell line derived from human embryonic retinal cells transformed with the Adenovirus Type 5 (Ad5) E1A and E1B genes, is used to produce E1-deleted Ad5 vectors such as the MRKAd5 HIV-1 gag vaccine. While whole, live PER.C6 cells are capable of growing as tumours when transplanted subcutaneously into immunodeficient nude mice at a high dosage, the process for vaccine production includes filtration steps and other methods which effectively preclude contamination by intact viable substrate cells. However, because of the neoplastic nature of this cell line, we carried out a series of investigations to assess the tumorigenic risk posed by residuals from the cell substrate in a vaccine. To address concerns about transmission of oncogenic DNA, we demonstrated that purified PER.C6 cellular DNA does not induce tumours in newborn hamsters or nude mice. To address concerns about other potential residuals, including hypothetical adventitious tumour viruses, we demonstrated that a PER.C6 cell lysate and a MRKAd5 HIV-1 gag vaccine produced on PER.C6 cells do not induce tumours in newborn hamsters or newborn rats. These results, in conjunction with the wide panel of viral safety tests performed on these cells, support the safety of the PER.C6 as a cell substrate for vaccine production.

Approaches to the release of a master cell bank of PER.C6 cells; a novel cell substrate for the manufacture of human vaccines

At Merck and Co. we have developed a recombinant E1 deficient adenovirus type 5 vaccine vector for HIV-1 and have adopted the PER.C6 cell line as a cell substrate for the manufacture of this vector for Phase I and II clinical trials. The PER.C6 cell line was developed at Crucell by the transfection of human primary embryonic retinoblasts with a transgene of E1 constructed with a minimum of E1 coding sequences to preclude homologous recombination generating replication-competent adenovirus, between E1 sequences in PER.C6 and adenovirus vectors with E1 deletions of the same molecular coordinates. We have developed a Master Cell Bank (MCB) of PER.C6 cells under serum-free conditions of suspension culture from a vial of PER.C6 cells obtained from Crucell. This MCB has been released according to an extensive panel of testing for the detection of adventitious viral agents, including assays for sterility and mycoplasma, in vivo and in vitro assays for the detection of viruses of human, bovine and porcine origin, replication competent adenoviruses, sensitive PERT assays for the detection of RT in supernatants of co-cultivations, electron microscopy and a panel of PCR-based assays for specific human and animal viruses. This MCB has been used for the manufacture of vaccine vector supporting a number of IND submissions for Phase I clinical trials over a three-year period during which the panel of PCR testing applied to the MCB has been judiciously expanded. Advances in QPCR technology, liquid handling systems, and more recently mass spectrometry offer the possibility that very broad panels of primers and probes capable of the detection of all known human viruses can be applied routinely to support the release of biologicals for human clinical trials. The impact of this breadth of testing on the continued reliance of classical in vivo and in vitro assays for adventitious viruses is clearly an emerging issue worthy of serious debate.

Clinical efficacy assessment in photodamaged skin of 0.5% and 1.0% idebenone

Idebenone is an antioxidant lower molecular weight analogue of coenzyme Q10. Previously, idebenone was shown to be a very effective antioxidant in its ability to protect against cell damage from oxidative stress in a variety of biochemical, cell biological, and in vivo methods, including its ability to suppress sunburn cell (SBC) formation in living skin. However, no clinical studies have been previously conducted to establish the efficacy of idebenone in a topical skincare formulation for the treatment of photodamaged skin. In this nonvehicle control study, 0.5% and 1.0% idebenone commercial formulations were evaluated in a clinical trial for topical safety and efficacy in photodamaged skin. Forty-one female subjects, aged 30-65, with moderate photodamaged skin were randomized to use a blind labelled (either 0.5% or 1.0% idebenone in otherwise identical lotion bases) skincare preparation twice daily for six weeks. Blinded expert grader assessments for skin roughness/dryness, fine lines/wrinkles, and global improvement in photodamage were performed at baseline, three weeks and six weeks. Electrical conductance readings for skin surface hydration and 35 mm digital photography were made at baseline after six weeks. Punch biopsies were taken from randomly selected subjects, baseline and after six weeks, and stained for certain antibodies (interleukin IL-6, interleukin IL-1b, matrixmetalloproteinase MMP-1, collagen I) using immunofluorescence microscopy. After six weeks' use of the 1.0% idebenone formula, a 26% reduction in skin roughness/dryness was observed, a 37% increase in skin hydration, a 29% reduction in fine lines/wrinkles, and a 33% improvement in overall global assessment of photodamaged skin. For the 0.5% idebenone formulation, a 23% reduction in skin roughness/dryness was observed, a 37% increase in skin hydration, a 27% reduction in fine lines/wrinkles, and a 30% improvement in overall global assessment of photodamaged skin. The immunofluorescence staining revealed a decrease in IL-1b, IL-6, and MMP-1 and an increase in collagen I for both concentrations.

Idebenone: a new antioxidant - Part I. Relative assessment of oxidative stress protection capacity compared to commonly known antioxidants

Topical applications of skin care products containing antioxidants have become increasingly popular. Numerous studies have elucidated the biological effects of these substances. General antiaging effects, anti-inflammatory properties, photoprotective properties, and prevention of ultraviolet (UV) immunosuppression have been documented. However, a standardized method to characterize and compare the properties and oxidative stress protection capacity of antioxidants was lacking. A multistep in vitro process utilizing a variety of biochemical and cell biological methods combined with in vivo studies was designed to compare the oxidative stress protective capacity of commonly used antioxidants. Data were presented for L-ascorbic acid, dl-alpha-tocopherol, kinetin, dl-alpha lipoic acid, ubiquinone, and idebenone. Methods included using UV-induced radical trapping/scavenging capacity measured by photochemiluminescence, pro-oxidative systems (LDL-CuSO(4), microsome-NADPH/ADP/Fe(3+)) with measurement of primary and secondary oxidation products, UVB irradiation of human keratinocytes, and in vivo evaluation, using the human sunburn cell (SBC) assay. Correlation and trends between in vitro and in vivo results were established, and the standardized test protocol was used to quantify oxidative stress protection capacity of antioxidants. Summarizing and totaling the data equally weighted for each oxidative stress study, the overall oxidative protection capacity scores of 95, 80, 68, 55, 52, and 41 were obtained for idebenone, dl-alpha tocopherol, kinetin, ubiquinone, L-ascorbic acid, and dl-alpha lipoic acid, respectively. The higher the score, the more effective the overall oxidative stress protection capacity of the antioxidant became. This multistep protocol may serve as a standard in investigating and comparing new putative antioxidants for topical use as well as a valuable tool to assess the anti-inflammatory properties, photoprotective properties, and prevention of UV immunosuppression of topical antioxidants.

An evaluation of the efficacy of Aqualox for microbiological control of industrial cooling tower systems

A comprehensive sampling protocol was employed to evaluate the efficacy of Aqualox, a biocide based on electrochemically activated water, against legionellae and heterotrophic bacteria in two industrial cooling tower systems. Both of the towers in the study remained free from evidence of Legionella spp. contamination throughout a five-month evaluation period, despite the previously demonstrated presence of legionellae in one of the test towers, and in two other towers on the same site, at levels well in excess of UK Health and Safety Commission (HSC) Approved Code of Practice and Guidance (ACOP) upper action limits. Levels of heterotrophic bacteria were controlled below 10(4) cfu/mL in both towers throughout most of the trial. Results also provided indirect evidence of significant activity against biofilm bacteria, with biofilm removal beginning almost immediately after commissioning of the Aqualox treatment systems. The results were particularly encouraging as the two towers studied had a long history of poor microbiological control using conventional bromine-based biocide products. Significant differences were observed between laboratory measurements of total viable counts on frequent liquid samples and those obtained from dip slides following HSC recommendations.

Evaluation of a Philippine community based rehabilitation programme

In 1991, the Philippine Department of Health implemented a Philippine Model of the World Health Organisation's Community Based Rehabilitation Programme initiative in pilot areas. The objective of this study was to explore whether, after seven years of operation, the Programme had actually been implemented as planned. The study was conducted in one pilot area in Rosario, La Union, a rural district of Luzon. The research used audit methodology to compare planned services with actual services. The main audit techniques used were record review, in-depth personal interview and focus group discussions. The study showed that such a programme, if properly organised and managed, can meet the needs of the people with disabilities who need rehabilitation. The Community Based Rehabilitation Programme represents a simple cost-effective approach for the delivery of disability prevention and rehabilitation services, particularly in rural areas that have little access to such services.

Modulation of the multidrug-resistance phenotype by new tropane alkaloid aromatic esters from Erythroxylum pervillei

Nine tropane alkaloid aromatic esters (1-9) were isolated from the roots of Erythroxylum pervillei by following their potential to reverse multidrug-resistance with vinblastine-resistant oral epidermoid carcinoma (KB-V1) cells. All isolates, including seven new structures (3-9), were evaluated against a panel of human cancer cell lines, and it was found that alkaloids 3 and 5-9 showed the greatest activity with KB-V1 cells assessed in the presence of vinblastine, suggesting that these new compounds are potent modulators of P-glycoprotein. Confirmatory results were obtained with human ovarian adenocarcinoma (SKVLB) cells evaluated in the presence of adriamycin and synergistic studies performed with several cell lines from the NCI tumor panel. The structures of the new compounds were determined using spectroscopic techniques. Single-crystal X-ray analysis was performed on the monoester, tropane-3 alpha,6 beta,7 beta-triol 3-phenylacetate (1).

The human genome and public policy: a nursing perspective

The Human Genome Project has completed a rough draft of the sequence that comprises human DNA. For the first time, the scientific discoveries have been conducted in tandem with research exploring the social, legal, and ethical implications of the research. Several committees have studied the policy implications of the genetics information explosion. The Secretary's Advisory Committee on Genetic Testing's report was received by the Secretary of the U.S. Department of Health and Human Services in November 2000 and contains recommendations for the oversight of genetic testing. Public policy issues that affect nursing practice in the area of genetics must be explored by individual nurses and professional nursing organizations.

Nanoparticle halos: a new colloid stabilization mechanism

A new mechanism for regulating the stability of colloidal particles has been discovered. Negligibly charged colloidal microspheres, which flocculate when suspended alone in aqueous solution, undergo a remarkable stabilizing transition upon the addition of a critical volume fraction of highly charged nanoparticle species. Zeta potential analysis revealed that these microspheres exhibited an effective charge buildup in the presence of such species. Scanning angle reflectometry measurements indicated, however, that these nanoparticle species did not adsorb on the microspheres under the experimental conditions of interest. It is therefore proposed that highly charged nanoparticles segregate to regions near negligibly charged microspheres because of their repulsive Coulombic interactions in solution. This type of nanoparticle haloing provides a previously unreported method for tailoring the behavior of complex fluids.

Social support, intrusive thoughts, and quality of life in breast cancer survivors

This study explores the moderating effect of social support on the relationship between cancer-related intrusive thoughts and quality of life. Sixty-four breast cancer survivors completed self-report measures of appraisal social support (the disclosure of thoughts and feelings to significant others), cancer-related intrusive thoughts, and quality of life. Controlling for demographic and treatment variables, the negative impact of cancer-related intrusive thoughts on both physical and mental quality of life measures was moderated by appraisal social support. For women with high levels of appraisal support, cancer-related intrusive thoughts had no significant relationship with quality of life. However, for women with low levels of appraisal support, the relationship between cancer-related intrusive thoughts and quality of life was significant and negative. These results suggest that appraisal social support can mitigate the impact of traumatic life events.

Control of directionality in integrase-mediated recombination: examination of recombination directionality factors (RDFs) including Xis and Cox proteins

Similarity between the DNA substrates and products of integrase-mediated site-specific recombination reactions results in a single recombinase enzyme being able to catalyze both the integration and excision reactions. The control of directionality in these reactions is achieved through a class of small accessory factors that favor one reaction while interfering with the other. These proteins, which we will refer to collectively as recombination directionality factors (RDFs), play architectural roles in reactions catalyzed by their cognate recombinases and have been identified in conjunction with both tyrosine and serine integrases. Previously identified RDFs are typically small, basic and have diverse amino acid sequences. A subset of RDFs, the cox genes, also function as transcriptional regulators. We present here a compilation of all the known RDF proteins as well as those identified through database mining that we predict to be involved in conferring recombination directionality. Analysis of this group of proteins shows that they can be grouped into distinct sub-groups based on their sequence similarities and that they are likely to have arisen from several independent evolutionary lineages. This compilation will prove useful in recognizing new proteins that confer directionality upon site-specific recombination reactions encoded by plasmids, transposons, phages and prophages.

Vaccinia virus blocks gamma interferon signal transduction: viral VH1 phosphatase reverses Stat1 activation

We have analyzed the effects of vaccinia virus (VV) on gamma interferon (IFN-gamma) signal transduction. Infection of cells with VV 1 to 2 h prior to treatment with IFN-gamma inhibits phosphorylation and nuclear translocation of Stat1 and consequently blocks accumulation of mRNAs normally induced by IFN-gamma. While phosphorylation of other proteins in the IFN-gamma pathway was not affected, activation of Stat1 by other ligand-receptor systems was also blocked by VV. This block of Stat1 activation was dose dependent, and although viral protein synthesis was not required, entry and uncoating of viral cores appear to be needed to block the accumulation of phosphorylated Stat1. These results suggest that a virion component is responsible for the effect. VV virions contain a phosphatase (VH1) that is sensitive to the phosphatase inhibitor Na(3)VO(4) but not to okadaic acid. Addition of Na(3)VO(4) but not okadaic acid restored normal Stat1 phosphorylation levels in VV-infected cells. Moreover, virions containing reduced levels of VH1 were unable to block the IFN-gamma signaling pathway. In vitro studies show that the phosphatase can bind and dephosphorylate Stat1, indicating that this transcription factor can be a substrate for VH1. Our results reveal a novel mechanism by which VV interferes with the onset of host immune responses by blocking the IFN-gamma signal cascade through the dephosphorylating activity of the viral phosphatase VH1.

Advanced practice in maternal/child nursing: history, current status, and thoughts about the future

Advanced practice nursing has undergone dramatic growth and change in during the past quarter century. Specialization in maternal/child health started with hospital-developed postlicensure programs which evolved into formal master's level programs. The first nurse-practitioner program in pediatrics was begun in 1965 at the University of Colorado. The last 25 years has seen an increase in clinical specialization and in advanced practice roles within the specialties. The growth of credentials and types of certification available have provided opportunities for nurses, but have also created confusion for consumers and other health care professionals. Current challenges facing advanced practice nurses include issues related to legal authority for scope of practice, direct reimbursement for services, and prescriptive authority. The current health care climate provides challenges and opportunities for nurses in advanced practice.

Species-specific elements in the large T-antigen J domain are required for cellular transformation and DNA replication by simian virus 40

The J domain of simian virus 40 (SV40) large T antigen is required for efficient DNA replication and transformation. Despite previous reports demonstrating the promiscuity of J domains in heterologous systems, results presented here show the requirement for specific J-domain sequences in SV40 large-T-antigen-mediated activities. In particular, chimeric-T-antigen constructs in which the SV40 T-antigen J domain was replaced with that from the yeast Ydj1p or Escherichia coli DnaJ proteins failed to replicate in BSC40 cells and did not transform REF52 cells. However, T antigen containing the JC virus J domain was functional in these assays, although it was less efficient than the wild type. The inability of some large-T-antigen chimeras to promote DNA replication and elicit cellular transformation was not due to a failure to interact with hsc70, since a nonfunctional chimera, containing the DnaJ J domain, bound hsc70. However, this nonfunctional chimeric T antigen was reduced in its ability to stimulate hsc70 ATPase activity and unable to liberate E2F from p130, indicating that transcriptional activation of factors required for cell growth and DNA replication may be compromised. Our data suggest that the T-antigen J domain harbors species-specific elements required for viral activities in vivo.

Ethnomedicinally selected plants as sources of potential analgesic compounds: indication of in vitro biological activity in receptor binding assays

A number of plant species used in traditional medicine for the relief of pain have been selected from the medicinal and scientific literature of China, South America, Asia and West Africa. Extracts were prepared and tested in three in vitro receptor radioligand binding assays to determine whether there was an indication of biological activity, in particular their selectivity to a single receptor implicated in the mediation of pain. The three neuropeptide receptors chosen were Bradykinin (BK II), expressed in Chinese hamster ovary cells (CHO), neurokinin 1 (NK 1) expressed in astrocytoma cells, and calcitonin gene related peptide (CGRP) which were all implicated in the mediation of acute pain in the mammaliancentral nervous system. The plant species chosen to investigate were Ageratum conyzoides, Barringtonia edulis, Croton tiglium, Ipomea pes-caprae, Panax ginseng, Physostigma venenosum, Sinomenium acutum, Solidago virgaurea, Symplocos leptophylla and Typhonium giganteum. The results showed that there was a strong indication of biological activity for some of the plants which are used ethnomedicinally to treat pain, in the three in vitro receptor binding assays used, and particular plant extracts exhibited selective action to a single receptor.

Identification and characterization of mycobacteriophage L5 excisionase

The well-characterized mycobacteriophage L5 forms stable lysogens in Mycobacterium smegmatis. Establishment of lysogeny involves integration of the phage genome into the chromosome of its mycobacterial hosts through an integrase-mediated site-specific recombination event. As L5 lysogens spontaneously generate free phage particles, prophage excision must also occur, although an L5 excisionase gene had not been identified. We show here that L5 gene 36 encodes the phage excisionase and is a small, heat-stable 56-amino-acid protein that strongly stimulates excisive recombination both in vivo and in vitro. The ability to manipulate the highly directional phage integration and excision reactions will provide powerful tools for the introduction, curing and recovery of foreign genes in recombinant mycobacterial strains.

Evaluation of the purity of a purified, inactivated hepatitis A vaccine (VAQTA)

Manufacture of VAQTA, an inactivated hepatitis A virus vaccine, includes extensive purification of the intact virus particle to remove endogenous components from the host cell culture lysate as well as compounds introduced in the upstream purification process. Analysis of the final purified hepatitis A virus product by SDS-PAGE prior to inactivation shows that greater than 95% of the protein in the preparation is found in four protein bands, which have been confirmed to be hepatitis A virus capsid proteins VP0, VP1, VP2 and VP3 based on Western blot and mass spectrometry analyses. Validation of the manufacturing process and direct analysis of the final product were used to demonstrate that no other specific host cell-derived components are detected and that process residuals are all below the limits of detection of the assays used. Establishment of a rigorous standard of high purity for this product was pursued to minimize the impact of impurities during clinical development of this product and will facilitate the incorporation of this product into combination vaccines.

Isolation of translactone-containing triterpenes with thrombin inhibitory activities from the leaves of Lantana camara

Methanolic extracts prepared from the leaves of Lantana camara have been found to inhibit human thrombin. An assay, in which thrombin activity is measured as a function of clot formation from fibrinogen, was used to guide the fractionation and purification of five principal active constituents (1-5), which were all characterized as 5,5-trans-fused cyclic lactone-containing euphane triterpenes.

Statistical shortcomings in licensing applications

This paper concerns the statistical work carried out with respect to clinical trials conducted for regulatory purposes. Although the general quality of such work has improved markedly over recent years and is now generally high, a number of shortcomings remain. A few of these arise from failure to follow well established statistical practice. Rather more arise from a poor understanding of areas of known statistical disagreement and from the unsatisfactory use of newer and more advanced techniques. Inadequacies in reporting statistical work are commonplace. Examples of all these shortcomings are provided and emphasis is placed on the value of a statistical contribution to overall summaries such as the clinical expert report.

The management of interim analyses in drug development

The ethical need for interim analyses in long-term trials of life-threatening conditions is well established, but recently there has been increased enthusiasm for the use of interim analyses in other areas of clinical research. Interim analysis is seen as a powerful tool in drug development to help reduce 'time to market' by allowing key decisions to be made earlier on the basis of one or more ongoing clinical trials. However, this goal can only be achieved without serious penalties if interim analyses are properly designed and executed, so that the integrity of the whole drug development programme is maintained. The purpose of this paper is to define procedures for the design and management of clinical trials which involve interim analyses. These procedures are intended to incorporate good clinical and statistical practice, hence maintaining high scientific standards not only of individual trials but also of the overall development programme. Aspects of design, conduct, analysis and dissemination of results are considered, with particular focus on the effective use of data monitoring committees in confirmatory efficacy trials.

A comparison of various estimators of a treatment difference for a multi-centre clinical trial

When a clinical trial is conducted at more than one centre it is likely that the true treatment effect will not be identical at each centre. In other words there will be some degree of treatment-by-centre interaction. A number of alternative approaches for dealing with this have been suggested in the literature. These include frequentist approaches with a fixed or random effects model for the observed data and Bayesian approaches. In the fixed effects model, there are two common competing estimators of the treatment difference, based on weighted or unweighted estimates from individual centres. Which one of these should be used is the subject of some controversy and we do not intend to take a particular methodological position in this paper. Our intention is to provide some insight into the relative merits of the indicated range of possible estimators of the treatment effect. For the fixed effects model, we also look at the merits of using a preliminary test for interaction assuming a 10 per cent significance level for the test. In order to make comparisons we have simulated a 'typical' trial which compares an active drug with a placebo in the treatment of hypertension, using systolic blood pressure as the primary variable. As well as allowing the treatment effect to vary between centres, we have concentrated on the particular case where one centre is out of line with the others in terms of its true treatment difference. The various estimators that result from the different approaches are compared in terms of mean squared error and power to reject the null hypothesis of no treatment difference. Overall, the approach that uses the fixed effects weighted estimator of overall treatment difference is recommended as one that has much to offer.

A Formulation of Trichoderma and Gliocladium to Reduce Damping-off Caused by Rhizoctonia solani and Saprophytic Growth of the Pathogen in Soilless Mix

Commercially manufactured cellulose granules (Biodac) were mixed with a sticker and fermentor-produced biomass of isolates of Trichoderma spp. and Gliocladium virens to produce a formulation in which chlamydospores in the biomass were "activated" with dilute acid. Activation resulted in the formation of young, actively growing hyphae of the biocontrol fungi within a 2- to 3-day period under no special aseptic conditions. Activated Biodac with biomass of isolates Gl-3, Gl-21, and Gl-32 of G. virens and isolate TRI-4 of T. hamatum applied to soilless mix at a rate of 1.5% (wt/wt) reduced damping-off of eggplant caused by Rhizoctonia solani (R-23) and resulted in stands comparable to that (88%) in noninfested soilless mix. Saprophytic growth of the pathogen was also reduced. The application of either of two activated Biodac formulations to provide the same amount (1.5% with 9.4 mg of biomass per g of Biodac or 0.2% with 75.0 mg of biomass per g of Biodac) reduced preemergence damping-off as well as saprophytic growth of R-23. Also, there was about a 10³-fold population increase of Gl-3 and TRI-4 in the soilless mix at the time of plant harvest compared with that provided to the soilless mix at the time of formulation addition. Activated Biodac of Gl-3 also reduced the spread of R-23 in soilless mix when the pathogen was applied at specific foci rather than evenly distributed. The inhibition of pathogen spread significantly reduced the postemergence damping-off of cucumber, eggplant, and pepper seedlings.

Seed Treatment Using Pre-infiltration and Biocontrol Agents to Reduce Damping-off of Corn Caused by Species of Pythium and Fusarium

Bioassays were conducted in a greenhouse at 18°C to determine the effectiveness of a seed treatment used in combination with biocontrol agents for the reduction of corn damping-off caused by species of Pythium and Fusarium. Corn seeds were infiltrated with tap water, drained, air-dried, and then coated with biomass of an antagonistic fungus, Gliocladium virens isolate Gl-3, or an antagonistic bacterium, Burkholderia cepacia isolates Bc-B or Bc-1, or a combination of Gl-3 with each of the bacterial isolates. A nonsterile field soil was infested with a combination of pathogens: Pythium ultimum, P. arrhenomanes, and Fusarium graminearum at 2 inoculum rates (1× and 4×). Pre-infiltration enhanced (P ≤ 0.05) disease control with most treatments at both inoculum rates. Treatments with biocontrol agents alone or in combination, as well as the fungicide captan, effectively reduced the disease at a pathogen inoculum rate of 1×, resulting in greater (P ≤ 0.05) seedling stands, plant height, and fresh weight, and lower (P ≤ 0.05) root rot severity compared with untreated seeds in infested soil. At a pathogen inoculum rate of 4×, stands were lower (P ≤ 0.01) and root-rot severity was higher (P ≤ 0.01) compared to those at 1× for all treatments. Nevertheless, coating seeds with all biocontrol agents (alone or in combination), except with Bc-1 alone, reduced disease (P ≤ 0.05) compared to untreated seeds in infested soil. At both inoculum rates of 1× and 4×, coating seeds with Gl-3 + Bc-B was more effective (P ≤ 0.05) in disease control than any other treatment, resulting in stands, growth rate (plant height and fresh weight), and root rot severity similar to plants from untreated seeds in noninfested soil. In addition, when the exudate from a 2-h infiltration of corn seed was added to the seeds during seed coating, seedling stand was often lower and root rot severity was often higher than those from infiltrated seeds (P ≤ 0.05). These results indicated that the infiltration process removed certain exudates, including nutrients and/or stimulants (not detected in this study) that might be utilized by pathogens to initiate seed infection. A thin-layer chromatography (TLC) profile of the exudates showed the presence of eight amino acids and three major carbohydrates.

New active substances authorized in the United Kingdom between 1972 and 1994

AIMS

The study was undertaken to assemble a list of all new active medicinal substances authorised in the United Kingdom between 1972 and 1994; to assess whether the pattern of introductions had changed; and to examine withdrawal rates and the reasons for withdrawal.

METHODS

The identities of those new active substances whose manufacturers had obtained Product Licences between 1972 and 1994 were sought from the Medicines Control Agency's product data-base. For each substance relevant information was retrieved including the year of granting the Product Licence, its therapeutic class, whether currently authorised (and, if not, reason for withdrawal), and its nature (chemical, biological etc.).

RESULTS

The Medicines Control Agency's data-base was cross-checked against two other data-bases for completeness. A total of 583 new active substances (in 579 products) were found to have been authorised over the study period. The annual rates of authorisation varied widely (9 to 40 per year). Whilst there was no evidence for any overall change in the annual rates of authorising new chemical entities, there has been a trend for increasing numbers of new products of biological origin to be authorised in recent years. Fifty-nine of the 583 new active substances have been withdrawn (1 each for quality and efficacy, 22 for safety, and 35 for commercial reasons).

CONCLUSIONS

For reasons that are unclear there is marked heterogeneity in the annual rates of authorisation of new active substances. Their 10 year survival is approximately 88% with withdrawals being, predominantly, for commercial or safety reasons. This confirms the provisional nature of assessments about safety at the time when a new active substance is introduced into routine clinical practice, and emphasises the importance of pharmacovigilance.