Prolonged treatment of cells with genistein modulates the expression and function of the cystic fibrosis transmembrane conductance regulator

BACKGROUND AND PURPOSE

Cystic fibrosis (CF) is caused by dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel. In the search for new CF therapies, small molecules have been identified that rescue the defective channel gating of CF mutants (termed CFTR potentiators). Here, we investigate the long-term effects of genistein, the best-studied CFTR potentiator, on the expression and function of CFTR.

EXPERIMENTAL APPROACH

We pre-treated baby hamster kidney (BHK) cells expressing wild-type or F508del-CFTR (the most common CF mutant) with concentrations of genistein that potentiate (30 microM) or inhibit (100 microM) CFTR function for 2 or 24 h at 37 degrees C before examining CFTR maturation, expression and single-channel activity.

KEY RESULTS

Using the iodide efflux technique, we found that genistein pre-treatment failed to restore function to F508del-CFTR, but altered that of wild-type CFTR. Pre-treatment of cells with genistein for 2 h had little effect on CFTR processing, whereas pre-treatment for 24 h either augmented (30 microM genistein) or impaired (100 microM genistein) CFTR maturation. Using immunocytochemistry, we found that all genistein pre-treatments increased the localization of CFTR protein to the cell surface. However, following the incubation of cells with genistein (100 microM) for 2 h, individual CFTR Cl(-) channels exhibited characteristics of channel block upon channel activation.

CONCLUSIONS AND IMPLICATIONS

Genistein pre-treatment alters the maturation, cell surface expression and single-channel function of CFTR in ways distinct from its acute effects. Thus, CFTR potentiators have the potential to influence CFTR by mechanisms distinct from their effects on channel gating.

Differential binding patterns of monoclonal antibody 2C4 to the ErbB3-p185her2/neu and the EGFR-p185her2/neu complexes

2C4 (Pertuzumab, Omnitarg) is a monoclonal antibody targeting p185(her2/neu), which is overexpressed in 30% of invasive breast cancer. 2C4 is currently in phase II clinical trials for several types of cancers. This antibody has been reported to disrupt the association between p185(her2/neu) and ErbB3. In our studies of epidermal growth factor receptor (EGFR)-p185(her2/neu) heterodimerization, we noted that 2C4 formed associations with the EGFR-p185(her2/neu) receptor complex. Our data argue against 2C4 as a universal heterodimerization blocker for p185(her2/neu), but indicate that cocktails of monoclonal antibodies binding distinct interaction surfaces of p185(her2/neu) will emerge as the most potent targeted therapy.

Dual agents loaded PLGA nanoparticles: systematic study of particle size and drug entrapment efficiency

PLGA nanoparticles simultaneously loaded with vincristine sulfate (VCR) and quercetin (QC) were prepared via O/W emulsion solvent evaporation. Six independent processing parameters and PLGA characteristics were assessed systematically to enhance the incorporation of the dual agents with different properties (VCR and QC, hydrophilic and hydrophobic molecule, respectively) into PLGA nanoparticles and control particle size. Approaches investigated for the enhancement of drug entrapment efficiencies and the controlling of particle size included the influence of the molecular weight (MW) of PLGA and the lactide-to-glycolide (L:G) ratio of PLGA, PLGA concentration, PVA concentration, initial QC content, acetone-to-dichloromethane (A/D) volume ratio, aqueous phase pH and aqueous to organic phase (W/O) volume ratio. The nanoparticles produced by optimal formulation were submicron size (139.5+/-4.3 nm, n=3) with low polydispersity index (0.095+/-0.031, n=3). Nanoparticles observed by transmission electron microscopy (TEM) showed extremely spherical shape. The entrapment efficiencies determined by high performance liquid chromatography (HPLC) by ultracentrifuge method were 92.84+/-3.37% for VCR and 32.66+/-2.92% for QC (n=3). The drug loadings were 0.0037+/-0.0001% for VCR and 1.36+/-0.12% for QC (n=3).

Endothelin(A) (ET(A)) and ET(B) receptor-mediated regulation of nitric oxide synthase 1 (NOS1) and NOS3 isoforms in the renal inner medulla

AIM

Our laboratory and others have shown that endothelin (ET)-1 directly stimulates nitric oxide (NO) production in inner medullary collecting duct (IMCD) cells. The goal of this study was to determine which NO synthase (NOS) isoforms in IMCD are sensitive to ET-1, and the role of ET(A) and ET(B) receptor activation in vivo and in vitro.

METHODS

NOS enzymatic activity and NOS isoform protein expression were examined in cultured IMCD-3 cells and isolated renal inner medulla. ET(B) receptor-deficient homozygous rats (sl/sl) have elevated levels of circulating ET-1 and lack a functional ET(B) signalling pathway in kidneys, and furthermore provides a unique model to study ET(A) receptor signalling in the renal inner medulla in vivo.

RESULTS

Incubation of IMCD-3 cells with exogenous ET-1 (50 nm) resulted in ET(A)-dependent increased NOS1 protein expression in IMCD-3 cells with no effect on NOS2 or NOS3 expression. ET(B) receptor antagonism has no effect on NOS expression in IMCD-3 cells. Consistent with in vitro results, cytosolic NOS1 protein expression was significantly greater in the renal inner medulla of sl/sl rats compared with heterozygous (sl/+) controls, with no alteration in NOS3 expression. In contrast to protein expression data, NOS1- and NOS3-specific enzymatic activities decreased in the cytosolic fraction from the renal inner medulla of sl/sl compared with sl/+.

CONCLUSION

These results provide evidence that both ET(A) and ET(B) receptors regulate NOS isoform activity in the renal inner medulla and specifically support the hypothesis that ET(A) receptor activation increases NOS1 expression.

Alpha-Phenyl-n-tert-butyl-nitrone attenuates lipopolysaccharide-induced neuronal injury in the neonatal rat brain

Although white matter damage is a fundamental neuropathological feature of periventricular leukomalacia (PVL), the motor and cognitive deficits observed later in infants with PVL indicate the possible involvement of cerebral neuronal dysfunction. Using a previously developed rat model of white matter injury induced by cerebral lipopolysaccharide (LPS) injection, we investigated whether LPS exposure also results in neuronal injury in the neonatal brain and whether alpha-phenyl-n-tert-butyl-nitrone (PBN), an antioxidant, offers protection against LPS-induced neuronal injury. A stereotactic intracerebral injection of LPS (1 mg/kg) was performed in Sprague-Dawley rats (postnatal day 5) and control rats were injected with sterile saline. LPS exposure resulted in axonal and neuronal injury in the cerebral cortex as indicated by elevated expression of beta-amyloid precursor protein, altered axonal length and width, and increased size of cortical neuronal nuclei. LPS exposure also caused loss of tyrosine hydroxylase positive neurons in the substantia nigra and the ventral tegmental areas of the rat brain. Treatments with PBN (100 mg/kg) significantly reduced LPS-induced neuronal and axonal damage. The protection of PBN was associated with an attenuation of oxidative stress induced by LPS as indicated by the reduced number of 4-hydroxynonenal, malondialdehyde or nitrotyrosine positive cells in the cortical area following LPS exposure, and with the reduction in microglial activation stimulated by LPS. The finding that an inflammatory environment may cause both white matter and neuronal injury in the neonatal brain supports the possible anatomical correlate for the intellectual deficits and the other cortical and deep gray neuronal dysfunctions associated with PVL. The protection of PBN may indicate the potential usefulness of antioxidants for treatment of these neuronal dysfunctions.

Determination of aesculin in rat plasma by high performance liquid chromatography method and its application to pharmacokinetics studies

A sensitive and reproducible high performance liquid chromatography method with UV detection was described for the determination of aesculin in rat plasma. After deproteinization by methanol using metronidazole as internal standard (I.S.), solutes were evaporated to dryness at 40 degrees C under a gentle stream of nitrogen. The residue was reconstituted in 100 microl of mobile phase and a volume of 20 microl was injected into the HPLC for analysis. Solutes were separated on a Diamonsil C18 column (250 mm x 4.6 mm i.d., 5 microm particle size, Dikma) protected by a ODS guard column (10 mm x 4.0 mm i.d., 5 microm particle size), using acetonitrile-0.1% triethylamine solution (adjusted to pH 3.0 using phosphoric acid) (10:90, v/v) as mobile phase (flow-rate 1.0 ml/min), and wavelength of the UV detector was set at 338 nm. No interference from any endogenous substances was observed during the elution of aesculin and internal standard (I.S., metronidazole). The retention times for I.S and aesculin were 10.4 and 12.4 min, respectively. The limit of quantification was evaluated to be 57.4 ng/ml and the limit of detection was 24.0 ng/ml. The method was used in the study of pharmacokinetics of aesculin after intraperitoneal injection (i.p.) administration in rats.

Novel two-step release system for the traditional Chinese medicine compound Danshen

A novel two-step release system for the traditional Chinese medicine compound Danshen was developed by combining an effervescent osmotic pump tablet (EOPT) and a pulsed-released tablet (PT) of compound Danshen into one hard capsule. The EOPT of Danshen was prepared with sodium chloride, mannitol, hydroxypropylmethylcellulose (HPMC), and sodium bicarbonate as osmotic agents. The osmotic pressure from EOPT was greatly enhanced by carbon dioxide generated from the reaction between sodium bicarbonate and acidic components from Danshen. It was shown that the tested Danshen components could be completely released from the prepared EOPT following a zero-order release for up to 12 h. The PT of compound Danshen was a three-layer coated tablet composed of organic acid and osmotic agents. Eudragit RL, HPMC and the mixture of EC and Eudragit RS, RL were the major constituents of the separation layer, swelling layer and controlling release membrane, respectively. The swelling test of the PT indicated that swelling is a prerequisite for drug release from this PT device. In addition, the swelling behavior further suggested the drug release mechanism of PT involves diffusion, the osmotic pumping effect, and organic acid-induced effect, among which the osmotic pumping effect was the most important. Moreover, there was no significant difference among the five active constituents in their release profiles from the final combined two-step release system of compound Danshen.

Determination of Colchicine in Mouse Plasma by High Performance Liquid-chromatographic Method with UV Detection and Its Application to Pharmacokinetic Studies

A simple and sensitive high performance liquid chromatography method with UV detection was described for the determination of colchicine (COL) in mouse plasma. After single-step deproteinization by acetonitrile using berberine hydrochloride as an internal standard (I.S.), solutes were separated on a Diamonsil C(18) column (250 mm x 4.6 mm I.D., 5 microm particle size) (Dikma), using acetonitrile-0.15% phosphoric acid solution (27:73, v/v) as mobile phase (flow-rate 1.0 ml/min); wavelength of the UV detector was set at 350 nm. No interference from any endogenous substances was observed during the elution of COL and internal standard (I.S., berberine hydrochloride). The retention times for COL and I.S. were 11.23 min and 8.82 min, respectively. The limit of quantification was evaluated to be 1.5 ng/ ml and the limit of detection was 0.5 ng/ml. The method was used in the study of pharmacokinetics of COL after intravenous injection (i.v.) and intraperitoneal injection (i.p.). The result indicated that COL disappears from the plasma according to a three compartment open model.

PLGA nanoparticles simultaneously loaded with vincristine sulfate and verapamil hydrochloride: systematic study of particle size and drug entrapment efficiency

PLGA nanoparticles simultaneously loaded with vincristine sulfate (VCR) and verapamil hydrochloride (VRP) were prepared via combining O/W emulsion solvent evaporation and salting-out method. Ten independent processing parameters and two materials characteristics were assessed systematically to enhance the incorporation of the two hydrophilic low molecular weight drugs into PLGA nanoparticles and minimize nanoparticles size. Approaches investigated for the enhancement of drug entrapment efficiencies and the minimization of particle size included the influence of the molecular weight (MW) of PLGA and the lactide to glycolide (L:G) ratio of PLGA, PLGA concentration, the degrees of hydrolyzation and polymerization of PVA, PVA concentration, initial VCR and VRP content, acetone to dichloromethane volume ratio, aqueous phase pH, salt concentration of aqueous phase, aqueous to organic phase volume ratio, sonication time, sonication energy and removal rate of organic solvents. The nanoparticles produced by optimal formulation were submicron size (111.4+/-2.35nm, n=3) and of low polydispersity (0.062+/-0.023, n=3). Nanoparticles observed by transmission electron microscopy (TEM) showed extremely spherical shape. The entrapment efficiencies determined with high performance liquid chromatogram (HPLC) by ultracentrifuge method were 55.35+/-4.22% for VCR and 69.47+/-5.34% for VRP, respectively (n=3).

Novel fibroblastic onion bulbs in a demyelinating avian peripheral neuropathy produced by riboflavin deficiency

The finding of novel fibroblastic onion bulb-like structures in peripheral nerves is reported for the first time in avian riboflavin deficiency. Day old broiler meat chickens were fed a riboflavin deficient diet (1.8 mg/kg) and were killed on postnatal days 6, 11, 16, 21 and 31, whereas control chickens were fed a conventional diet containing 5.0 mg/kg riboflavin. The fibroblastic onion bulb-like structures were found in sciatic and brachial nerves from day 11 onwards and consisted of long cytoplasmic processes of hypertrophied fibroblasts surrounding demyelinated, remyelinated and normally myelinated axons. The fibroblast cytoplasmic processes often enveloped more than one nerve fibre to produce a unique compound-like onion bulb structure. These onion bulb-like structures occurred early in the course of segmental demyelination at the same time as tomacula formation and became increasingly more prominent in the later stages of demyelination and remyelination. The molecular basis of formation of these unique structures requires further study as to the basis of the attraction of the fibroblast processes to nerve fibres associated with myelinating Schwann cells. The model may also be useful in investigating the role of endoneurial fibroblasts in endoneurial fibrosis as the early fibroblastic response in the onion bulbs is distinct from the more usual fibroblastic deposition of collagen in end-stage peripheral nerve disease.

Microscopic and macroscopic signatures of antiferromagnetic domain walls

Magnetotransport measurements on small single crystals of Cr, the elemental antiferromagnet, reveal the hysteretic thermodynamics of the domain structure. The temperature dependence of the transport coefficients is directly correlated with the real-space evolution of the domain configuration as recorded by x-ray microprobe imaging, revealing the effect of antiferromagnetic domain walls on electron transport. A single antiferromagnetic domain wall interface resistance is deduced to be of order 5 x 10(-5) mu Omega cm(2) at a temperature of 100 K.

Characterization of the structures involved in localization of the SUN proteins to the nuclear envelope and the centrosome

The nuclear envelope forms a selective barrier that separates the cytoplasm from the nucleus. During mitosis the nuclear envelope breaks down so that the microtubule network can form contacts with the kinetochore and guide chromosome segregation. Previous studies have suggested a model in which the centrosome and the microtubule network may play a role in nuclear envelope breakdown through as yet unidentified interactions with proteins localized to the nuclear envelope. In the current study we characterized a nuclear envelope protein SUN2 and identified a substructure involved in its localization to the nuclear envelope. We found that a structurally related protein, SUN1, may be localized to the nuclear envelope through a different mechanism. Furthermore, the SUN2 protein can form different assemblies, including homodimers and heterodimers with SUN1. Finally, we provide evidence indicating that SUN1 and SUN2 may form a physical interaction between the nuclear envelope and the centrosome.

Survey sequencing of soybean elucidates the genome structure, composition and identifies novel repeats

In order to expand our knowledge of the soybean genome and to create a useful DNA repeat sequence database, over 24 000 DNA fragments from a soybean [Glycine max (L.) Merr.] cv. Williams 82 genomic shotgun library were sequenced. Additional sequences came from over 29 000 bacterial artificial chromosome (BAC) end sequences derived from a BstI library of the cv. Williams 82 genome. Analysis of these sequences identified 348 different DNA repeats, many of which appear to be novel. To extend the utility of the work, a pilot study was also conducted using methylation filtration to estimate the hypomethylated, soybean gene space. A comparison between 8366 sequences obtained from a filtered library and 23 788 from an unfiltered library indicate a gene-enrichment of ~3.2-fold in the hypomethylated sequences. Given the 1.1-Gb soybean genome, our analysis predicts a ~343-Mb hypomethylated, gene-rich space.

Single-walled carbon nanotubes-mediated in vivo and in vitro delivery of siRNA into antigen-presenting cells

Antigen-presenting cells such as dendritic cells (DCs) play a critical role in inducing and regulating immune responses. One effective strategy for DC-based immunotherapy is to regulate maturation and function of DC. In this study, we apply single-walled carbon nanotubes (SWNTs) to carry small interfering RNA (siRNA) to reach, enter and genetically modify DCs in vivo. We prepared positively charged SWNTs (SWNTs+) using 1,6-diaminohexane which was demonstrated by transmission electron microscopy equipped with energy-dispersive X-ray spectroscopy and atomic force microscope. The functionalized SWNTs+ could absorb siRNA to form complexes of siRNA with SWNTs. These siRNA:SWNT+ complexes were preferentially taken up by splenic CD11c+ DCs, CD11b+ cells and also Gr-1+CD11b+ cells comprising DCs, macrophages and other myeloid cells to silence the targeting gene. Suppressor of cytokine signaling 1 (SOCS1) restricts the ability of DCs to break self-tolerance and induce antitumor immunity. Infusion of SWNTs+ carrying SOCS1siRNA reduced SOCS1 expression and retarded the growth of established B16 tumor in mice, indicating the possibility of in vivo immunotherapeutics using SWNTs-based siRNA transfer system.

Role of interleukin-6 in lipopolysaccharide-induced brain injury and behavioral dysfunction in neonatal rats

There are increasing data in support of the hypothesis that inflammatory cytokines are involved in neonatal white matter damage. Despite extensive study of the proinflammatory cytokines tumor necrosis factor-alpha and interleukin-1beta, the role of interleukin-6 in the development of white matter damage is largely unknown. In the present study, the role(s) of interleukin-6 in mediating lipopolysaccharide-induced brain injury and behavioral changes was investigated by the intracerebral injection of lipopolysaccharide with interleukin-6 neutralizing antibody in the 5-day-old rat brain. Brain injury was examined in brain sections at postnatal day 8 and postnatal day 21. Behavioral tests including righting reflex, wire hanging maneuver, cliff avoidance, locomotor activity, gait analysis, responses in the elevated plus-maze and passive avoidance were performed from postnatal day 3 to postnatal day 21. Changes in astroglia, microglia and oligodendrocytes were studied using immunohistochemistry in the postnatal day 21 rat brain. Our results show that interleukin-6 antibody attenuated lipopolysaccharide-induced brain lateral ventricle dilation and improved neurobehavioral performance. Interleukin-6 antibody also suppressed lipopolysaccharide-induced astrogliosis and microglial activation, and increased the number of oligodendrocytes in white matter. However, no changes of tumor necrosis factor-alpha and interleukin-1beta were detected. In contrast, no histopathological changes and glial activation were observed in rats injected with only interleukin-6. The present study indicates that the contribution to brain injury by interleukin-6 depends on its interaction with other lipopolysaccharide-induced agents and not on interleukin-6 alone.

Paranodal pathology in Tangier disease with remitting-relapsing multifocal neuropathy

Pathological studies of a sural nerve biopsy in a man with Tangier disease presenting as a remitting-relapsing multifocal neuropathy showed abnormalities in the paranodal regions, including lipid deposition (65%) and redundant myelin foldings, with various degrees of myelin splitting and vesiculation (43%) forming small tomacula and abnormal myelin terminal loops (4%). The internodal regions were normal in the majority of myelinated fibres. Abnormal lipid storage was also present in the Schwann cells of the majority of unmyelinated fibres (67%). The evidence suggests that the noncompacted myelin region of the paranode is a preferential site for lipid storage in the myelinated Schwann cell, and that the space-occupying effects of the cholesterol esters leads to paranodal malfunction and tomacula formation as the pathological basis for the multifocal relapsing-remitting clinical course.

Early paranodal myelin swellings (tomacula) in an avian riboflavin deficiency model of demyelinating neuropathy

INTRODUCTION

Disruption of the complex architectural and molecular organization of the paranodal region of myelinated peripheral nerve fiber may initiate the evolving time dependent process of segmental demyelination. In support of this notion was the finding of focal paranodal myelin swellings (tomacula) due to redundant folding of myelin sheaths, early in the time course of an avian riboflavin deficiency model of demyelinating neuropathy.

METHODS

Newborn broiler meat chickens were maintained either on a routine diet containing 5.0 mg/kg riboflavin (control group) or a riboflavin-deficient diet containing 1.8 mg/kg riboflavin. Riboflavin concentrations in the liver were measured at postnatal day 11. Peripheral nerves were morphologically examined at days 6, 11, 16 and 21 using light and electron microscopy and teased nerve fiber techniques.

RESULTS

Riboflavin-deficient chickens showed signs of a neuropathy from days 8 and pathological examination of peripheral nerves revealed a demyelinating neuropathy with paranodal tomacula formation starting on day 11. Paranodal tomacula consisted of redundant myelin infoldings or outfoldings, increased in size and frequency after day 11. After day 16, the paranodal swellings showed prominent degenerative changes accompanied by an increased frequency of myelinated fibers showing demyelination.

CONCLUSION

Tomacula due to redundant myelin folds are generally considered a remyelination phenomenon, yet in this avian riboflavin deficiency model of demyelination, the paranodal tomacula occurred early in the course of demyelination.

Shear modulus and plasticity of a driven charge density wave

We have probed the effects of transverse variations in pinning strength on charge-density-wave (CDW) structure in NbSe3 by x-ray micro-beam diffraction. In ribbonlike crystals having a large longitudinal step in thickness, the CDW first depins on the thick side of the step, causing rotations of the CDW wave vector. By measuring these rotations as a function of position and electric field, the corresponding shear strains are determined, allowing the CDW's shear modulus to be estimated. These results demonstrate the usefulness of x-ray microdiffraction as a tool in studying collective dynamics in electronic crystals.

Minocycline alleviates hypoxic-ischemic injury to developing oligodendrocytes in the neonatal rat brain

The role of minocycline in preventing white matter injury, in particular the injury to developing oligodendrocytes was examined in a neonatal rat model of hypoxia-ischemia. Hypoxia-ischemia was achieved through bilateral carotid artery occlusion followed by exposure to hypoxia (8% oxygen) for 15 min in postnatal day 4 Sprague-Dawley rats. A sham operation was performed in control rats. Minocycline (45 mg/kg) or normal phosphate-buffered saline was administered intraperitoneally 12 h before and immediately after bilateral carotid artery occlusion+hypoxia and then every 24 h for 3 days. Nissl staining revealed pyknotic cells in the white matter area of the rat brain 1 and 5 days after hypoxia-ischemia. Hypoxia-ischemia insult also resulted in apoptotic oligodendrocyte cell death, loss of O4+ and O1+ oligodendrocyte immunoreactivity, and hypomyelination as indicated by decreased myelin basic protein immunostaining and by loss of mature oligodendrocytes in the rat brain. Minocycline significantly attenuated hypoxia-ischemia-induced brain injury. The protective effect of minocycline was associated with suppression of hypoxia-ischemia-induced microglial activation as indicated by the decreased number of activated microglia, which were also interleukin-1beta and inducible nitric oxide synthase expressing cells. The protective effect of minocycline was also linked with reduction in hypoxia-ischemia-induced oxidative and nitrosative stress as indicated by 4-hydroxynonenal and nitrotyrosine positive oligodendrocytes, respectively. The reduction in hypoxia-ischemia-induced oxidative stress was also evidenced by the decreases in the content of 8-isoprostane in the minocycline-treated hypoxia-ischemia rat brain as compared with that in the vehicle-treated hypoxia-ischemia rat brain. The overall results suggest that reduction in microglial activation may protect developing oligodendrocytes in the neonatal brain from hypoxia-ischemia injury.