Natural variation in drug susceptibility to HCV polymerase inhibitors in treatment-naïve HCV patient isolates

Summary.  To assess the natural variation in drug susceptibility among treatment-naïve hepatitis C virus (HCV) patient isolates, the susceptibilities of chimeric replicons carrying the HCV NS5B polymerase from up to 51 patient isolates against a panel of diverse HCV nonnucleoside polymerase inhibitors were evaluated using a replicon-based transient replication assay. Some patient to patient variation in susceptibility to the panel of three HCV nonnucleoside polymerase inhibitors was observed. Linear regression and correlation analyses revealed no correlations among the susceptibilities to the polymerase inhibitors tested. Our results suggest that variable antiviral responses to HCV nonnucleoside polymerase inhibitors may be observed because of the natural variation in baseline susceptibility. In addition, the lack of correlation among the susceptibilities to three classes of HCV polymerase inhibitors evaluated here supports their possible combined use in a combination therapy strategy.

Estimation of inhibitory quotient using a comparative equilibrium dialysis assay for prediction of viral response to hepatitis C virus inhibitors

The relationship of inhibitory quotient (IQ) with the virologic response to specific inhibitors of human hepatitis C virus (HCV) and the best method to correct for serum protein binding in calculating IQ have not been addressed. A common method is to determine a fold shift by comparing the EC(50) values determined in cell culture in the absence and presence of human serum (fold shift in EC(50) ), but this method has a number of disadvantages. In the present study, the fold shifts in drug concentrations between 100% human plasma (HP) and cell culture medium (CCM) were directly measured using a modified comparative equilibrium dialysis (CED) assay for three HCV protease inhibitors (PIs) and for a novel HCV inhibitor GS-9132. The fold shift values in drug concentration between the HP and CCM (CED ratio) were ∼1 for SCH-503034, VX-950 and GS-9132 and 13 for BILN-2061. These values were ∼3-10-fold lower than the fold shift values calculated from the EC(50) assay for all inhibitors except BILN-2061. Using the CED values, a consistent pharmacokinetic and pharmacodynamic relationship was observed for the four HCV inhibitors analysed. Specifically, an approximate 1 log(10) reduction in HCV RNA was achieved with an IQ close to 1, while 2-3 and greater log(10) reductions in HCV RNA were achieved with IQ values of 3-5 and greater, respectively. Thus, use of CED to define IQ provides a predictive and quantitative approach for the assessment of the in vivo potency of HCV PIs and GS-9132. This method provides a framework for the evaluation of other classes of drugs that are bound by serum proteins but require the presence of serum for in vitro evaluation.

An experimental study on the effect of spacer on concentration polarization in a long channel reverse osmosis membrane cell

This study was to experimentally investigate the performance and organic fouling behaviour in a 1-m long RO membrane channel with or without spacer for desalting. It was found that local permeate flux distributed heterogeneously along the long membrane channel without a spacer inserted due to exponential growth of concentration polarization, which also resulted in decreasing salt rejection and increasing organic fouling along the membrane channel in the downstream direction. This heterogeneity could be lessened by inserting a spacer into the channel, which mitigated concentration polarization due to the enhanced turbulence caused by a spacer, especially at the downstream portion of the channel. However, in the upstream of the channel, inserting a spacer exerted an additional vertical resistance which might counteract the effect of concentration polarization mitigation by a spacer and caused a lower permeate flux. This suggests that it is necessary to consider the integral effect of spacer for designing an RO membrane module and an overall RO system in order to prevent extra resistance, reduce concentration polarization and membrane fouling.

Structure and phase transitions of monolayers of intermediate-length n-alkanes on graphite studied by neutron diffraction and molecular dynamics simulation

We present evidence from neutron diffraction measurements and molecular dynamics (MD) simulations of three different monolayer phases of the intermediate-length alkanes tetracosane (n-C(24)H(50) denoted as C24) and dotriacontane (n-C(32)H(66) denoted as C32) adsorbed on a graphite basal-plane surface. Our measurements indicate that the two monolayer films differ principally in the transition temperatures between phases. At the lowest temperatures, both C24 and C32 form a crystalline monolayer phase with a rectangular-centered (RC) structure. The two sublattices of the RC structure each consists of parallel rows of molecules in their all-trans conformation aligned with their long axis parallel to the surface and forming so-called lamellas of width approximately equal to the all-trans length of the molecule. The RC structure is uniaxially commensurate with the graphite surface in its [110] direction such that the distance between molecular rows in a lamella is 4.26 A=sqrt[3a(g)], where a(g)=2.46 A is the lattice constant of the graphite basal plane. Molecules in adjacent rows of a lamella alternate in orientation between the carbon skeletal plane being parallel and perpendicular to the graphite surface. Upon heating, the crystalline monolayers transform to a "smectic" phase in which the inter-row spacing within a lamella expands by approximately 10% and the molecules are predominantly oriented with the carbon skeletal plane parallel to the graphite surface. In the smectic phase, the MD simulations show evidence of broadening of the lamella boundaries as a result of molecules diffusing parallel to their long axis. At still higher temperatures, they indicate that the introduction of gauche defects into the alkane chains drives a melting transition to a monolayer fluid phase as reported previously.

Effects of methylprednisolone on bone mineral density and microarchitecture of trabecular bones in rats with administration time and assessed by micro-computed tomography

BACKGROUND

Little research exists on the dynamic effects of glucocorticoids on bone mineral density (BMD) and microarchitecture of trabecular bones of rats assessed by micro-computed tomography (micro-CT).

PURPOSE

To investigate time-related changes in the BMD and microarchitecture of trabeculae in rats exposed to glucocorticoid.

MATERIAL AND METHODS

Female Sprague-Dawley rats were recruited into a baseline group, glucocorticoid-treated groups, or control groups. Glucocorticoid-treated rats were given daily subcutaneous injections of methylprednisolone at a dosage of 3.5 mg/kg for 1 or 9 weeks. A high-resolution micro-CT was used to identify the densitometric and microarchitectural properties of trabeculae in both the proximal metaphysis of tibiae and the sixth lumbar vertebrae (L6).

RESULTS

Compared with baseline rats, volumetric BMD, tissue BMD, bone volume fraction, trabecular number, and degree of anisotropy of trabeculae from tibiae or L6 increased in control rats and glucocorticoid-treated rats with time; however, changes in the latter group were smaller. Compared with control rats at each time point, a decrease occurred in volumetric BMD, tissue BMD, bone volume fraction, trabecular number, degree of anisotropy, and trabecular connectivity density in trabecular bones from tibiae or L6 in glucocorticoid-treated rats. The decrease was greater in week 9 compared to week 1. Contrarily, an increase was noted in trabecular thickness, trabecular separation, and structure model index in glucocorticoid-treated rats. A time-related analysis within glucocorticoid-treated groups in both skeletal regions showed a decline in bone volume fraction, trabecular connectivity density, trabecular number, and degree of anisotropy with time, but trabecular thickness and trabecular separation were elevated.

CONCLUSION

Methylprednisolone can inhibit bone mineralization and bone mass gain with growth in rats. It can also deteriorate microarchitecture of trabeculae in a time-dependent or an accumulative dose-dependent manner. Further, the remaining trabeculae appear to thicken in order to adapt to altered stress.

Visualization of the degradation of a disulfide polymer, linear poly(ethylenimine sulfide), for gene delivery

Polyethylenimine (PEI) shows high transfection efficiency and cytoxicity due to its high amine density. The new disulfide cationic polymer, linear poly(ethylenimine sulfide) (l-PEIS), was synthesized for efficient and safe gene delivery. As the amine density of l-PEIS increased, the transfection efficiency also increased. l-PEIS-6 and l-PEIS-8 show transfection efficiencies that are similar to that of PEI. However, cytotoxicity of l-PEIS was not observed due to the biodegradable disulfide bond. The disulfide bonds are stable in the oxidative extracellular condition and can be degraded rapidly in the reductive intracellular condition. The degradation of l-PEIS in HeLa cells was visualized by fluorescence microscopy using the probe-probe dequenching effect of BODIPY-FL fluorescence dye. l-PEIS was degraded completely within 3 h.

Hydrogen-dependent denitrification in an alternating anoxic-aerobic SBR membrane bioreactor

A novel hydrogenotrophic denitrification system, which consisted of a sequencing batch membrane bioreactor, was evaluated for simultaneous removal of nitrate and soluble microbial products (SMP) from a synthetic groundwater feed. A hollow fiber membrane diffuser was used for bubble-less diffusion of hydrogen into the bioreactor under anoxic condition followed by aerobic SMP removal and biomass filtration. During the anoxic period, the nitrate loading of 0.328 kg N m(-3) d(-1) was completely denitrified to below detectable levels. A denitrification rate of 0.8 kg N m(-3) d(-1) was obtained at steady state biomass concentrations of 1,162 mg I(-1). During the aerobic period when biomass filtration was performed, 81% of SMP produced within the anoxic phase was retained by the membrane, 9% was biologically removed, 5% was passed through the membrane and 5% was discharged during the wasting of mixed liquor. The aerobic cycle was instrumental as it allowed for effective biomass filtration via membrane scouring and assisted in further reduction of effluent organic matter.

Incorporating membrane gas diffusion into a membrane bioreactor for hydrogenotrophic denitrification of groundwater

A hydrogenotrophic denitrification system, comprising a suspended growth membrane bioreactor (MBR) with membrane hydrogen gas diffusion, was developed to remove nitrate from groundwater. A hollow fiber gas permeable membrane module was designed for hydrogen delivery and a commercially available hollow fiber membrane module was used for solid/liquid separation. The MBR was operated at an SRT of 20 days and at room temperature. Four nitrate loading rates of 24, 48, 96 and 192 NO3(-)-N mg I(-1) d(-1) were applied to the system. As the nitrate loading was raised, pH increased due to increased denitrification and release of OH- ions. The oxidation reduction potential (ORP) remained fairly stable when full denitrification was achieved, but increased when nitrate loading rates reached 192 NO3(-)-N mg I(-1) d(-1) and residual nitrate was present in the reactor. Nitrate removal was complete (100%) in the first three nitrate loadings and 72% in the system with 192 NO3(-)-N mg I(-1) d(-1). Nitrate utilization rates of 30.6, 23.4, and 37.7 g NO3(-)-N m(-3) d(-1) were achieved in the first three loadings. Average effluent dissolved organic carbon (DOC) concentration of approximately 8 mg l(-1) was observed in all four nitrate loading regimes, possibly owing to the generation and release of soluble microbial bi-products (SMP).

Poly(ethylene oxide sulfide): New Poly(ethylene glycol) Derivatives Degradable in Reductive Conditions

Poly(ethylene oxide sulfide) (PEOS), polymers consisting of an internal ethylene oxide oligomer and disulfide linkage, were synthesized and characterized. The degree of polymerization was dependent upon temperature, dimethyl sulfoxide condition, and monomer hydrophobicity. The stability of PEOS was measured by the size exclusion chromatography method after the incubation both with and without 5 mM glutathione. The disulfide bond was stable in the extracellular condition but completely degraded in 2 h in the reductive cytosolic condition. Hydrophilic PEOS polymers showed no cytotoxicity on the HepG2 cell line. On the basis of these properties, PEOS can be applied in many drug delivery fields.

New cationic lipids for gene transfer with high efficiency and low toxicity: T-shape cholesterol ester derivatives

New degradable cationic ester lipids with 'T-shape' configurations were synthesized and tested for gene delivery carrier. Their transfection efficiency and toxicity were compared with commercially available cationic lipids, DOTMA, DOSPA, and DC-Chol. They showed efficient transfection activity and almost no toxicity on mammalian cell lines. Their ester bond degradation was monitored by (1)H NMR.

Improved efficacy of chemotherapy for glioblastoma by radiation-induced opening of blood-brain barrier: clinical results

PURPOSE

To improve the efficacy of chemotherapy for glioblastoma through the radiation-induced opening of the blood-brain barrier (BBB).

METHODS AND MATERIALS

In two previous articles, we have described the results of brain scanning using technetium 99m-labeled somatostatin and the measurement of methotrexate (MTX) concentrations in blood and cerebrospinal fluid (CSF) after i.v. injection. We discovered that the BBB and blood-cerebrospinal fluid barrier opened to a certain extent after 20- to 40-Gy irradiation, thus increasing the degree to which MTX permeated the brain tissue. On the basis of these findings, we retrospectively analyzed the outcome in 56 patients with glioblastoma given either chemotherapy (CCNU) after 20- to 40-Gy irradiation (28 patients) or radiation therapy alone (28 patients).

RESULTS

The 1-, 3-, and 5-year survival rates were 57.14%, 22.50%, and 15.00% in the combined-therapy group and 17.86%, 7.14%, and 3.57% in the radiotherapy alone group, respectively. The respective median survival times were 29.11 +/- 6.99 and 9.86 +/- 3.45 months (p < 0.001), which represented a statistically significant difference.

CONCLUSION

Our study further confirms that opening of the BBB induced by irradiation with 20-40 Gy may optimize the effects of intracranial chemotherapy.

Carbohydrate binding properties of banana (Musa acuminata) lectin I. Novel recognition of internal alpha1,3-linked glucosyl residues

Examination of lectins of banana (Musa acuminata) and the closely related plantain (Musa spp.) by the techniques of quantitative precipitation, hapten inhibition of precipitation, and isothermal titration calorimetry showed that they are mannose/glucose binding proteins with a preference for the alpha-anomeric form of these sugars. Both generate precipitin curves with branched chain alpha-mannans (yeast mannans) and alpha-glucans (glycogens, dextrans, and starches), but not with linear alpha-glucans containing only alpha1,4- and alpha1,6-glucosidic bonds (isolichenan and pullulan). The novel observation was made that banana and plantain lectins recognize internal alpha1,3-linked glucosyl residues, which occur in the linear polysaccharides elsinan and nigeran. Concanavalin A and lectins from pea and lentil, also mannose/glucose binding lectins, did not precipitate with any of these linear alpha-glucans. This is, the authors believe, the first report of the recognition of internal alpha1,3-glucosidic bonds by a plant lectin. It is possible that these lectins are present in the pulp of their respective fruit, complexed with starch.

Carbohydrate binding properties of banana (Musa acuminata) lectin II. Binding of laminaribiose oligosaccharides and beta-glucans containing beta1,6-glucosyl end groups

This paper extends our knowledge of the rather bizarre carbohydrate binding poperties of the banana lectin (Musa acuminata). Although a glucose/mannose binding protein which recognizes alpha-linked gluco-and manno-pyranosyl groups of polysaccharide chain ends, the banana lectin was shown to bind to internal 3-O-alpha-D-glucopyranosyl units. Now we report that this lectin also binds to the reducing glucosyl groups of beta-1,3-linked glucosyl oligosaccharides (e.g. laminaribiose oligomers). Additionally, banana lectin also recognizes beta1,6-linked glucosyl end groups (gentiobiosyl groups) as occur in many fungal beta1,3/1,6-linked polysaccharides. This behavior clearly distinguishes the banana lectin from other mannose/glucose binding lectins, such as concanavalin A and the pea, lentil and Calystegia sepium lectins.

[Therapeutic effect on glioblastoma of chemotherapy on the basis of brain irradiation]

OBJECTIVE

To study the efficacy of chemotherapy for glioblastoma on the basis of brain irradiation.

METHODS

It was previously reported that the permeability of the blood brain barrier (BBB) to methotrexate could be increased by brain irradiation. In this study, glioblastoma patients were divided into 2 groups, 28 patients in each group. On group of patients was treated with CCNU or BCNU after having given 20-40 Gy irradiation to the brain. The other group of patients received radiation treatment alone.

RESULTS

The 1-, 3-, and 5-year survival rate of the two groups of patients was 57.1%, 22.5%, 15.0% and 17.9%, 7.1%, 3.6%, respectively. The median survival time was 29.7 +/- 7.0 and 9.7 +/- 3.5 months, respectively (P < 0.001).

CONCLUSION

Increase in permeability of the BBB after 20-40 Gy brain irradiation may provide an optimal chance for intracranial chemotherapy of glioblastoma.

Two different neurodegenerative diseases caused by proteins with similar structures

The downstream prion-like protein (doppel, or Dpl) is a paralog of the cellular prion protein, PrP(C). The two proteins have approximately 25% sequence identity, but seem to have distinct physiologic roles. Unlike PrP(C), Dpl does not support prion replication; instead, overexpression of Dpl in the brain seems to cause a completely different neurodegenerative disease. We report the solution structure of a fragment of recombinant mouse Dpl (residues 26-157) containing a globular domain with three helices and a small amount of beta-structure. Overall, the topology of Dpl is very similar to that of PrP(C). Significant differences include a marked kink in one of the helices in Dpl, and a different orientation of the two short beta-strands. Although the two proteins most likely arose through duplication of a single ancestral gene, the relationship is now so distant that only the structures retain similarity; the functions have diversified along with the sequence.

Rapid determination of the binding affinity and specificity of the mushroom Polyporus squamosus lectin using frontal affinity chromatography coupled to electrospray mass spectrometry

The binding affinity and specificity of the mushroom Polyporus squamosus lectin has been determined by the recently developed method of frontal affinity chromatography coupled to electrospray mass spectrometry (FAC/MS). A micro-scale affinity column was prepared by immobilizing the lectin ( approximately 25 microg) onto porous glass beads in a tubing column (9.8 microl column volume). The column was then used to screen several oligosaccharide mixtures. The dissociation constants of 22 sialylated or sulfated oligosaccharides were evaluated against the immobilized lectin. The lectin was found to be highly specific for Neu5Acalpha2-6Galbeta1-4Glc/GlcNAc containing oligosaccharides with K(d) values near 10 microM. The FAC/MS assay permits the rapid determination of the dissociation constants of ligands as well as a higher throughput screening of compound mixtures, making it a valuable tool for affinity studies, especially for testing large numbers of compounds.

Farnesyl anthranilate suppresses the growth, in vitro and in vivo, of murine B16 melanomas

The numbers of isoprene residues and unsaturated bonds, cis/trans configuration, and head group polarity influence the tumor-suppressive potency of acyclic isoprenoid hydrocarbons and alcohols; within the series tested, trans, trans farnesol had the greatest potency. Geraniol esters had increased potency relative to that of the free alcohol. Farnesyl anthranilate induced a concentration-dependent decrease in the B16 melanoma cell population, in part due to an increased proportion of cells in the G1 phase of the cell cycle and in part by the increased the proportion of apoptotic cells. Farnesyl anthranilate (1.5 mmol/kg diet) significantly suppressed the growth of implanted B16 melanomas and lowered the plasma cholesterol levels of tumor-free mice.

Isolation and identification of novel tocotrienols from rice bran with hypocholesterolemic, antioxidant, and antitumor properties

Two novel tocotrienols were isolated from stabilized and heated rice bran, apart from the known alpha-, beta-, gamma-, and delta-tocopherols and tocotrienols. These new tocotrienols were separated by HPLC, using a normal phase silica column. Their structures were determined by ultraviolet, infrared, nuclear magnetic resonance, circular dichroism, and high-resolution mass spectroscopies and established as desmethyl tocotrienol [3, 4-dihydro-2-methyl-2-(4,8,12-trimethyltrideca-3'(E),7'(E), 11'-trienyl)-2H-1-benzopyran-6-ol] and didesmethy tocotrienol [3, 4-dihydro-2-(4,8,12-trimethyltrideca-3'(E),7'(E), 11'-trienyl)-2H-1-benzopyran-6-ol]. These tocotrienols significantly lowered serum total and LDL cholesterol levels and inhibited HMG-CoA reductase activity in chickens. They had much greater in vitro antioxidant activities and greater suppression of B16 melanoma cell proliferation than alpha-tocopherol and known tocotrienols. Results indicated that the number and position of methyl substituents in tocotrienols affect their hypocholesterolemic, antioxidant, and antitumor properties.

[Effect of low dose of inhaled corticosteroid combined with small dose of oral theophylline on treatment of bronchial asthma]

OBJECTIVE

To investigate the effect of small dose of oral theophyllin combined with low dose of inhaled beclomethasone dipropionate (BDP) on clinical symptoms, bronchial responsiveness and hypothalamic-pituitary-adrenal axis (HPAA).

METHODS

43 patients with mild-moderate bronchial asthma were randomly divided into A and B groups. 21 subjects in group A were treated with oral substained release theophyllin (Protheo) (200 mg/night) and inhaled BDP (300 micrograms/day); 22 cases in group B received inhaled BDP (600 micrograms/day) and oral placebo.

RESULT

Before and 13 weeks after the treatment, symptom scores, peak flow(PEF), and peak flow rate (PEFR) for group A were (1.8 +/- 0.9) and (0.10 +/- 0.30), (295 +/- 98) L/min and (444 +/- 150) L/min, (22 +/- 8)% and (9 +/- 3)% respectively, and those for group B were (1.90 +/- 0.70) and (0.10 +/- 0.30), (328 +/- 129) L/min and (441 +/- 146) L/min, (24 +/- 7)% and (9 +/- 3)% respectively, which were remarkably improved in both groups (P < 0.01), and bronchial provocation responsiveness to histamine tests (BHR) in both groups were also improved significantly (P < 0.01). There were no differences between two groups (P < 0.05). Frequency of using inhaled beta 2 agonist to relieve nocturnal asthmatic attacks in group B (3.9 +/- 1.7) was significantly greater than that in group A (1.3 +/- 1.0, P < 0.05). Plasma ACTH concentrations, basic cortisol levels and cortisol responses to ACTH before and 13 weeks after the treatment in group B were (31 +/- 13) ng/L and (20 +/- 8) ng/L, (95 +/- 50) micrograms/L and (86 +/- 48) micrograms/L, (156 +/- 98)% and (74 +/- 46)% respectively, which were decreased significantly after the treatment (P < 0.05). There were no such changes in group A.

CONCLUSIONS

It was suggested that small dose of oral theophylline combined with low dose of inhaled BDP might have the same effect on relief of clinical symptoms and bronchial responsiveness, without suppression on HPAA function, comparing with relatively higher dose of inhaled BDP.

Purification and characterization of a Neu5Acalpha2-6Galbeta1-4Glc/GlcNAc-specific lectin from the fruiting body of the polypore mushroom Polyporus squamosus

A lectin has been purified from the carpophores of the mushroom Polyporus squamosus by a combination of affinity chromatography on beta-D-galactosyl-Synsorb and ion-exchange chromatography on DEAE-Sephacel. Gel filtration chromatography, SDS-polyacrylamide gel electrophoresis, and N-terminal amino acid sequencing indicated that the native lectin, designated P. squamosus agglutinin, is composed of two identical 28-kDa subunits associated by noncovalent bonds. P. squamosus agglutinin agglutinated human A, B, and O and rabbit red blood cells but precipitated only with human alpha(2)-macroglobulin, of many glycoproteins and polysaccharides tested. The detailed carbohydrate binding properties of the purified lectin were elucidated using three different approaches, i.e. precipitation inhibition assay (in solution binding assay), fluorescence quenching studies, and glycolipid binding by lectin staining on high-performance thin layer chromatography (solid-phase binding assay). Based on the results obtained by these assays, we conclude that although the P. squamosus lectin binds beta-D-galactosides, it has an extended carbohydrate-combining site that exhibits highest specificity and affinity toward nonreducing terminal Neu5Acalpha2, 6Galbeta1,4Glc/GlcNAc (6'-sialylated type II chain) of N-glycans (2000-fold stronger than toward galactose). The strict specificity of the lectin for alpha2,6-linked sialic acid renders this lectin a valuable tool for glycobiological studies in biomedical and cancer research.

Xanthosoma sagittifolium tubers contain a lectin with two different types of carbohydrate-binding sites

An unusual lectin possessing two distinctly different types of carbohydrate-combining sites was purified from tubers of Xanthosoma sagittifolium L. by consecutive passage through two affinity columns, i.e. asialofetuin-Sepharose and invertase-Sepharose. SDS-polyacrylamide gel electrophoresis, N-terminal amino acid sequencing, and gel filtration chromatography of the purified lectin showed that the X. sagittifolium lectin is a heterotetrameric protein composed of four 12-kDa subunits (alpha(2)beta(2)) linked by noncovalent bonds. The results obtained by quantitative precipitation and hapten inhibition assays revealed that the lectin has two different types of carbohydrate-combining sites: one type for oligomannoses, which preferentially binds to a cluster of nonreducing terminal alpha1,3-linked mannosyl residues, and the other type for complex N-linked carbohydrates, which best accommodates a non-sialylated, triantennary oligosaccharide with N-acetyllactosamine (i.e. Galbeta1,4GlcNAc-) or lacto-N-biose (i.e. Galbeta1,3GlcNAc-) groups at its three nonreducing termini.