Correlation between the activities of alpha-helical antimicrobial peptides and hydrophobicities represented as RP HPLC retention times

PTP7 is a 13-amino acid residue peptide designed from gaegurin 6, an antimicrobial peptide isolated from skin secretions of Rana rugosa. In order to examine the effect of hydrophobicity on antimicrobial activity, a series of PTP7 derivatives were constructed and analyzed the activity against bacteria and artificial membrane. We found that the mean hydrophobicity by simple summation of hydrophobicity of each constituent amino acid did not necessarily describe the hydrophobic property of antimicrobial peptides. The mean hydrophobicity did not show close correlation with the observed hydrophobicity by measuring reverse phase high performance liquid chromatography (RP HPLC) retention time. The observed hydrophobicity represented as RP HPLC retention time correlated well with the activity against artificial membrane and Gram positive bacterial species, such as Staphylococcus aureus, Staphylococcus epidermidis, and Micrococcus luteus, rather than mean hydrophobicity. However, antimicrobial activity against Gram negative bacteria, such as Escherichia coli, did not show correlation with RP HPLC retention time. These data indicate that the RP HPLC retention time should be exploited rather than the mean hydrophobicity in the analysis of the relationship between hydrophobicity and antimicrobial activity.

Stabilization of interchange modes in mirror plasmas by a nonlinear rf-plasma wave coupling process

Experimental and theoretical studies are made of the consequences of a nonlinear coupling process between pump rf waves and interchange modes in mirror plasmas. It is demonstrated that the interchange-stable operation window exists depending on the applied rf power and gamma=omega(0)/Omega(i), where omega(0) (Omega(i)) is the angular frequency of the applied rf wave (ion cyclotron frequency). Results are shown that the nonlinear wave coupling process gives rise to the operation window near the resonance (gamma approximately equal to 1), which is elucidated by theoretical analyses combined with full rf wave simulations.

Structural determination of the low-coverage phase of Al on Si(001) surface

The atomic structure of Al layer on Si(001)-(2 x 1) surface has been studied by coaxial impact collision ion scattering spectroscopy. When 0.5 monolayer (ML) of Al atoms are adsorbed on Si(001) at room temperature, it is found that Al adatoms are dimerized and Al ad-dimers are oriented parallel to the underlying Si dimers at the position of centering T3 site with a height of 1.02 Angstroms from the first layer of Si(001). The bond length of the Al dimer is 2.67 Angstroms. With increasing Al coverage up to one ML, Al ad-dimers still occupied near T3 site and the next favorable site is near HH site.

Treadmill running promotes functional recovery and decreases brain-derived neurotrophic factor mRNA expression following sciatic crushed nerve injury in rats

AIM

Peripheral nerve injuries are commonly encountered clinical problems and often result in severe functional deficits. In the present study, the effects of treadmill running on the recovery rate of locomotor function and the expression of brain-derived neurotrophic factor (BDNF) mRNA following sciatic crushed nerve injury in rats were investigated.

METHODS

EXPERIMENTAL DESIGN

Comparative investigation was performed over 14 days.

SETTING

Experimental animal laboratory.

PARTICIPANTS

24 male Sprague-Dawley rats weighing 200+/-10 g. Animals were randomly assigned into 3 groups: the sham-operation group, the sciatic nerve injury group, and the sciatic nerve injury and running group.

INTERVENTIONS

The right sciatic nerve was crushed for 30 s using a surgical clip. Rats of the running group were made to run on a treadmill for 30 min once a day for 12 consecutive days.

MEASURES

Functional recovery was analyzed using a walking track analysis which can be quantified with the sciatic function index (SFI) and BDNF mRNA expression was analyzed using reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Sciatic crushed nerve injury showed characteristic gait changes showing decrease of SFI value and treadmill running significantly enhanced the SFI value. The level of BDNF mRNA expression was increased following sciatic crushed nerve injury and treadmill running significantly suppressed the sciatic nerve injury-induced increment of BDNF mRNA expression.

CONCLUSIONS

It can be suggested that treadmill running after peripheral nerve injury is effective in the functional recovery by inhibition on the over-expression of BDNF mRNA.

Structural analysis of the reconstructed Si(001)-C surface

The atomic structure of reconstructed Si(001)c(4 x 4)-C surface has been studied by coaxial impact collision ion scattering spectroscopy. When the 100L of ethylene (C(2)H(4)) molecules have been exposed on Si(001)-(2 x 1) surface at 700 degrees C, it is found that C atoms cause the ordering of missing Si dimer defects and occupy the fourth layer of Si(001) directly below the bridge site. Our results provide the support for the previous model in which a missing dimer structure is accompanied by C incorporation into the subsurface.

Magnetic resonance findings of primary central nervous system T-cell lymphoma in immunocompetent patients

PURPOSE

To describe the MR findings of primary central nervous system T-cell lymphoma (T-PCNSL) in immunocompetent patients.

MATERIAL AND METHODS

Seven patients with pathologically proven T-PCNSL were included in our study. The number, location, shape, enhancement pattern, and signal intensity of the tumors were determined. Diffusion-weighted images (DWI) and perfusion-weighted images (PWI) were obtained in four and two patients, respectively. Apparent diffusion coefficients (ADCs) were generated, and regions of interest were defined in each lesion.

RESULTS

Four patients with T-PCNSL had a single mass, while the others had multiple lesions (four, three, and two lesions, respectively). All seven cases of T-PCNSL had a supratentorial location: 12 in the subcortical area and 1 in the thalamus. No leptomeningeal involvement was noted. All tumors showed iso- to low T1 and iso- to slightly high T2 signal intensity to the adjacent gray matter. Rim enhancement was seen in 5 of the 7 patients (71.4%), while heterogeneous and homogeneous enhancement was seen in each of two. On DWI and ADC maps, the enhancing lesions showed slight hyperintensity in three patients (mean ADC ratio, 0.92 +/- 0.06) and iso-intensity in the other (ADC ratio, 1.02 +/- 0.05). Cystic areas consistent with necrosis were noted in three patients. High-signal intensity area in the cortex was noted on T1-weighted images in three patients, suggesting hemorrhage. In two patients, the same signal intensity area was noted within the mass. The two masses on the relative cerebral blood volume (rCBV) map demonstrated either similar or slightly higher signal intensity than that of the contralateral white matter. The rCBV ratios of these two masses were 1.27 +/- 0.16 and 1.35 +/- 0.2, respectively.

CONCLUSION

T-PCNSLs show a predilection for a subcortical location, a relatively high incidence of cortical or intratumoral hemorrhage, rim enhancement, or cystic-areas consistent with necrosis on magnetic resonance imaging. The lower rCBV ratio of the tumor might be helpful in differentiating T-PCNSL from other brain tumors such as high-grade glioma.

Role of C-terminal heptapeptide in pore-forming activity of antimicrobial agent, gaegurin 4

Gaegurin 4 (GGN4) is an antimicrobial peptide of 37 amino acids isolated from the skin of a frog, Rana rugosa. GGN4 has a disulfide bond between the residues 31 and 37, which is highly conserved among the antimicrobial peptides isolated from skin of the genus, Rana. However, the role of this C-terminal heptapeptide motif is not well understood. In this work, we compared the membrane effects of the full-length GGN4 (C37) and GGN4 1-30 (C30), which is devoid of the C-terminal seven amino acids to elucidate the function of the C-terminal motif. C37 induced significantly larger membrane conductance (>10x) in the model lipid bilayers formed with acidic and neutral phospholipids and larger K+ efflux from gram-positive (>30x) and gram-negative bacteria. However, the pores induced by C37 and C30 were not different in their permeability to K+ over Cl- (permeability ratio of K+ to Cl- = 4.8-7.1). In addition, the pore-forming effect of C37 or C30 in acidic membranes was not different from that in neutral membranes. Furthermore, C37-induced K+ efflux was not significantly decreased by the reducing agent, dithiothreitol. The results indicate that C-terminal heptapeptide sequence plays an important role in maintaining the high pore-forming activity of GGN4, but does not participate in forming GGN4-induced pore structure. The disulfide bond in this region does not appear critical for such high ionophoric activity of GGN4.

Structure-activity relationships of antimicrobial peptides from the skin of Rana esculenta inhabiting in Korea

The anuran (frogs and toads) skin is a rich source of antimicrobial peptides that can be developed therapeutically. We searched the skin secretions of Korean Rana esculenta for antimicrobial peptides, and isolated two cationic peptides with antimicrobial activity and little hemolytic activity: a 46-residue peptide of the esculentin-1 family and a 24-residue peptide of the brevinin-1 family. Their sequences showed some differences from the esculentins-1 and brevinins-1 of European Rana esculenta, indicating that sequence diversification of anuran skin antimicrobial peptides can arise from differences in habitat as well as from species differences. The 46-residue peptide named esculentin-1c had broad antimicrobial activity, while the 24-residue peptide named brevinin-1Ed exhibited limited activity. The solution structure of brevinin-1Ed was in good agreement with that of other brevinin-1-like peptides, with an amphipathic alpha-helix spanning residues 3-20, stabilized in membrane-mimetic environments. The weak bioactivity of brevinin-1Ed was attributable to the unusual presence of an anionic amino acid in the middle of the helical hydrophilic face. This report contributes to world-wide investigations of the structure-activity relationships and evolutional diversification of anuran-skin antimicrobial peptides.

P27kip1 regulates the apoptotic response of gastric epithelial cells to Helicobacter pylori

BACKGROUND

Helicobacter pylori infection increases the risk of gastric cancer but the molecular mechanisms responsible are not well understood. Gastric cells chronically exposed to H pylori in vitro develop resistance to apoptosis associated with low levels of p27, a cyclin dependent kinase inhibitor and haplo insufficient tumour suppressor gene that is downregulated in gastric cancer.

AIM

To determine whether the low level of p27 protein is responsible for the resistance to apoptosis of gastric cancer cells.

METHODS

The effects of increasing the expression of p27 protein were examined by transiently and stably transfecting a plasmid encoding full length p27 mRNA into apoptosis resistant gastric cancer cell lines with low p27 expression that were derived from AGS gastric cancer cells by chronic H pylori coculture followed by dilutional cloning.

RESULTS

Low p27 expression in the apoptosis resistant derivative cell lines was associated with an approximate 30% decrease in p27 mRNA and an 80% decrease in p27 protein that was not due to increased proteasome dependent degradation of p27 protein. Transient or stable transfection with p27 constructs partially restored the sensitivity of the apoptosis resistant cells to 5-fluorouracil and H pylori induced apoptosis without altering spontaneous apoptotic cell death.

CONCLUSIONS

These results demonstrate that p27 positively regulates, at least in part, the apoptotic response of gastric epithelial cells to H pylori. Low gastric p27 may promote gastric carcinogenesis associated with H pylori infection by inhibiting apoptotic pathways.

Experimental measurement of the electron energy distribution function in the radio frequency electron cyclotron resonance inductive discharge

Recently, the existence of electron cyclotron resonance (ECR) in a weakly magnetized inductively coupled plasma (MICP) has been evidenced [ChinWook Chung et al., Phys. Rev. Lett. 80, 095002 (2002)]. The distinctive feature of the ECR effect in the MICP is efficacious heating of low-energy electrons. In the present paper, electron heating characteristics in the MICP have been investigated by observing electron energy distribution function dependencies on various external parameters such as gas pressure, driving frequency, and rf power (electron density). It is found that the ECR effect on electron heating becomes enhanced with decreasing pressure or increasing driving frequency. The ECR heating becomes weak at high rf power due to the electron-electron collisions.

Synergistic inhibitory effect of cationic peptides and antimicrobial agents on the growth of oral streptococci

Although chlorhexidine is one of the most efficacious antimicrobial agents used for the prevention of dental caries, side effects limit its application. The effects of gaegurin 6 (GGN6), an animal-derived cationic peptide, and its derivatives PTP6 and PTP12 on the growth of oral streptococci were investigated to assess the potential of these agents for use in the prevention of dental caries. The minimal inhibitory concentrations of the peptides for inhibition of the growth of oral streptococci (Streptococcus mutans , S. sobrinus, S. sanguis and S. gordonii) ranged from 1.2 to 8.2 muM. The peptides also exhibited marked synergistic antibacterial effects with chlorhexidine or xylitol. The most effective combinations (fractional inhibitory concentration index of 0.5) were xylitol with GGN6 against S. gordonii 10558 and chlorhexidine with either GGN6 or PTP6 against S. sobrinus OMZ-175. These results indicate that cationic peptides alone or in combination with chlorhexidine or xylitol might prove effective for the inhibition of the growth of cariogenic oral streptococci in situ.

Outcome after radical prostatectomy with a pretreatment prostate biopsy Gleason score of ≥8

OBJECTIVE

To determine the outcome and predictors of recurrence in patients with a pretreatment prostate biopsy Gleason score (GS) of >/= 8 and treated with radical prostatectomy (RP).

PATIENTS AND METHODS

We retrospectively reviewed 1048 consecutive patients who underwent RP by one surgeon (M.S.S.); patients who had a pretreatment biopsy GS of >/= 8 were identified. Information was recorded on patient age, initial prostate specific antigen (PSA) level, clinical stage, biopsy GS, pathology GS, extraprostatic extension (EPE), tumour volume, surgical margin status, seminal vesicle invasion (SVI), and lymph node involvement. The results were assessed statistically using the Kaplan-Meier method, univariate log-rank tests and multivariate analysis using Cox's proportional hazards regression.

RESULTS

In all, 123 patients met the initial selection criteria; 44 were excluded from further analyses (five salvage RP, 23 < 1 year follow-up and 16 adjuvant treatment). Thus 79 patients were included in the uni- and multivariate analyses; 25 (31%) patients had a GS of </= 7 in the RP specimen and 54 (69%) remained at GS >/= 8. The mean follow-up was 55 months, the age of the patients 63 years and the mean (sd) initial PSA level 13 (12) ng/mL. The overall biochemical failure rate was 38% (41% if the final GS was >/= 8 and 32% if it was </= 7). For those with a GS of >/= 8 in the RP specimen, 20% (11/54) were organ-confined; two patients (2.5%) in this group developed local recurrence. If the final GS was </= 7, 52% (13/25) were organ-confined. In the univariate analysis, significant risk factors for recurrence were PSA >/= 20 ng/mL, EPE, SVI, a positive surgical margin and tumour volume. Cox's proportional regression indicated that a PSA of >/= 20 ng/mL (hazard ratio 7.9, 95% confidence interval 2.6-24.2, P < 0.001), the presence of EPE (4.2, 1.6-10.9, P = 0.004) and a positive surgical margin (3.8, 1.5-9.7, P = 0.005) were significant independent predictors in a multivariate analysis.

CONCLUSION

RP is a reasonable treatment option for patients with a prostate biopsy GS of >/=8 and clinical stage T1-2. These patients have a high chance of remaining disease-free if their PSA level is </= 20 ng/mL. Patients with a pretreatment biopsy GS of >/= 8 should be counselled about the potential differences between the biopsy and the RP specimen GS.

Treadmill exercise increases cell proliferation in hippocampal dentate gyrus in alcohol-intoxicated rats

AIM

Effect of treadmill exercise on hippocampal cell proliferation under normal conditions has been well documented; however, this effect under alcohol intoxication conditions is not clarified, yet. In the present study, the effect of treadmill exercise on cell proliferation in the dentate gyrus in alcohol-intoxicated rats was investigated.

METHODS

EXPERIMENTAL DESIGN

comparative investigation on number of 5-bromo-2'-deoxyuridine (BrdU)-positive cells in the dentate gyrus 8 days after commencement.

SETTING

animal laboratory.

PARTICIPANTS

male Sprague-Dawley rats of 5 weeks in age weighing 150+/-10 g.

INTERVENTION

animals were divided into 4 groups: the control-rest group, the control-exercise group, the alcohol-treated-rest group, and the alcohol-treated-exercise group. Animals of the alcohol-treated groups were injected intraperitoneally with alcohol (2 g/kg) once a day for 3 days. All animals were injected BrdU (50 mg/kg) intraperitoneally, and rats of exercise groups were made to run on treadmill for 30 min each day for 5 days following alcohol administration.

MEASURES

mean number of BrdU-positive cells in dentate gyrus was observed via immunohistochemistry.

RESULTS

Treadmill exercise significantly increased the number of BrdU-positive cells in the dentate gyrus. Also, treatment with alcohol for 3 days inhibited cell proliferation and treadmill exercise alleviated alcohol-induced inhibition of new cell formation.

CONCLUSION

These results suggest the possibility that treadmill exercise may help in improvement following alcohol-induced brain damage.

Concepts and approaches to in situ luminescence dating of Martian sediments

In this paper we present the concept of a robotic instrument for in situ luminescence dating of near-surface sediments on Mars. The scientific objectives and advantages to be gained from the development of such an instrument are described, and the challenges presented by the Mars surface environment to the design and operation of the instrument are outlined.

Endoscopic hemoclipping using a transparent cap in technically difficult cases

BACKGROUND AND STUDY AIMS

Technical difficulties have been experienced in endoscopic hemoclipping on the posterior wall of the body of the stomach because the angle of approach is tangential. It has been suggested that the use of a transparent cap on the tip of the endoscope could help to solve this problem. The purpose of this study was to examine the efficacy of endoscopic hemoclipping using a transparent cap over the tip of the endoscope.

PATIENTS AND METHODS

A total of 74 patients with a bleeding peptic ulcer or stigmata of recent hemorrhage underwent endoscopic hemoclipping. Technical difficulty in hemoclipping was experienced in 18 patients and the transparent cap was used in these cases. We therefore conducted a nonrandomized prospective study to compare bleeding control with the hemoclip with and without the aid of a transparent cap.

RESULTS

There were no statistically significant differences between the patients treated with the cap and those treated without the cap with regard to the initial hemostasis rate (94.4 % vs. 91.1 %), the rebleeding rate (11.7 % vs. 11.8 %), or the permanent hemostasis rate (94.4 % vs. 96.4 %).

CONCLUSIONS

Although there was no statistically significant difference between patients treated with or without a transparent cap, hemoclipping with the aid of the cap made it possible to clip a lesion too tangential to be clipped without it. However, this study did not compare conventional hemoclipping with hemoclipping using a cap because the cap was only used in cases in which conventional clipping had failed.

In vitro activities of native and designed peptide antibiotics against drug sensitive and resistant tumor cell lines

In order to develop peptide agents with reduced length and enhanced tumoricidal activity, we have designed gaegurin 6 (GGN6) derivatives through deletions and/or substitutions of amino acids. The deletion of hydrophobic amino terminal region completely abolished antitumor activity whereas the deletion of carboxy terminal region had little influence on antitumor activity. Antitumor activity of the PTP peptides did not correlate with antibacterial activity. PTP7, the most potent derivative, was found to have comparable antitumor activity to GGN6 in spite of reduced number of amino acids which is about half the size of gaegurin 6; furthermore, it showed little cytotoxicity on PBMCs and RBCs. GGN6 and PTP7 also showed equivalent cytotoxicity against drug sensitive (MCF-7) and multidrug-resistant cell lines (MCF-7/DOX). Plasma membrane blebbing and DNA fragmentation of peptide-treated tumor cells indicated that the peptides could induce apoptosis in tumor cells. These results suggest that GGN6 and its derivatives can be developed as new anticancer agents and may provide a new strategy for overcoming MDR which is a major problem in cancer therapy.

Temporal and sequential analysis of microglia in the substantia nigra following medial forebrain bundle axotomy in rat

Dopaminergic neurons in the substantia nigra pars compacta undergo apoptosis after transection of the medial forebrain bundle. We have assessed the temporal and sequential activities of microglia in these events by examining the complement-3 (OX-42), major histocompatibility complex class II antigen presentation (OX-6) and phagocytic activity (ED1), and correlating these indicators with dopaminergic neuronal loss. Microglia in the ipsilateral substantia nigra pars reticulata evinced activation morphology at 12 h postaxotomy. Phagocytic microglia apposed dying dopaminergic neurons in the pars compacta starting at 3 days postlesion; their number increased through 14 days and slowly decreased. Nuclear chromatin condensation and significant loss of tyrosine hydroxylase-positive dopaminergic neurons occurred around 7 days postlesion. In contrast to microglial expression of interleukin-1beta and inducible nitric oxide synthase at the axotomy site, nigral microglia were interleukin-1beta and inducible nitric oxide synthase-negative. Consistently, RNase protection assays showed that interleukin-1beta and inducible nitric oxide synthase transcripts in nigra were equivocal. The present data support the idea that phagocytosis of axotomized neurons by activated microglia is not limited to dead neurons but includes dying neurons probably without cytotoxic effects of inflammatory substances, such as interleukin-1beta or nitric oxide.

Two cases of steakhouse syndrome associated with nutcracker esophagus

The most common type of esophageal food-related foreign body is the meat bolus, which is frequently associated with underlying esophageal stenosis. Herein, we report two cases of meat bolus impaction associated with nutcracker esophagus. In the first case, the 63-year-old male patient had chest discomfort and swallowing difficulty after ingestion of butcher's meat. In the second case, the 55-year-old male patient had complained of swallowing difficulty after ingestion of chicken. In both cases, no pathologic findings were observed endoscopically after removal of the esophageal meat bolus. We performed esophageal manometry, which showed very high amplitudes of esophageal pressure in the mid- and distal esophagus. These findings were consistent with nutcracker esophagus. These cases show that esophageal motility disorder may be the cause of esophageal foreign body impaction, and esophageal manometry should be performed for evaluation of the cause of foreign body, especially in an endoscopically normal patient.

A sensitive and specific detection of Human herpesvirus 8 by polymerase chain reaction and dot blot hybridization

Polymerase chain reaction (PCR) is a powerful technique of detecting Human herpesvirus 8 (HHV-8), but has a limited sensitivity and specificity. A new assay of HHV-8 based on combination of PCR with dot blot hybridization (DBH) was developed and evaluated for its sensitivity and specificity. An HHV-8-specific primer pair, ORF26out was used for amplification of target DNA. When the PCR product was detected visually the limit of detection was 0.1 ng DNA isolated from HHV-8-infected BC-3 cells. For DBH, the DNA amplified with the primer pair ORF26in specific for HHV-8 was labeled with digoxigenin (DIG). This DIG-labeled probe was capable of detecting 1.0 ng of DNA isolated from HHV-8-infected BC-3 cells. On the other hand, PCR combined with DBH (PCR/DBH) was more sensitive than PCR or DBH alone and also very specific. The sensitivity of PCR/DBH was higher than that of PCR and DBH alone. The PCR/DBH assay can be applied efficiently to confirm the presence of HHV-8 in clinical samples and to differentiate specifically HHV-8 infection from other viral infections.

Brooks' posterior stabilisation surgery for atlantoaxial instability: review of 54 cases

PURPOSE

To assess the effectiveness of Brooks' posterior stabilisation and fusion for the unstable atlantoaxial joint due to congenital dysplastic dens and trauma.

METHODS

We retrospectively studied records of 54 patients (36 males and 18 females; age range, 3-58 years) who underwent Brooks' posterior stabilisation procedure between March 1975 and December 1999, at the Catholic University of Korea Medical Center and Dong-Shin General Hospital, Seoul. A single-stranded Kirschner wire was used to stabilise the first 19 cases (thin wires in 12 cases and thick wires in 7), and double-stranded wires were used in the next 35 cases (thin wires in 4 cases and thick wires in 31). After surgery, patients were immobilised in bed with light Halter traction of the head, followed by cervical bracing.

RESULTS

Fusion was observed by X-ray postoperatively at 15 weeks in 48 patients. Reduction was achieved in 3 luxation cases (including the single case of rotatory fixation). Brooks' fusion failed in 4 patients with dens fractures and 2 with dens anomaly. Four dens fractures in cases of successful Brooks' fusion in Brooks' fusion did not unite. Wire failure occurred in 4 cases of thin single-stranded wire fixation, namely, 2 cases of dens fractures and 2 of dens anomaly.

CONCLUSION

Brooks' procedure is safe and has a high fusion rate when double-stranded strong wire fixation of the atlantoaxial joint is combined with meticulous bone grafting and subsequent cervical bracing.

Human neural stem cells: electrophysiological properties of voltage-gated ion channels

We have characterized the profile of membrane currents in an immortalized human neural stem cell line, HB1.F3 cells, using whole-cell patch clamp technique. Human neural stem cell line generated from primary cell cultures of embryonic human telencephalon using a replication-incompetent retroviral vector containing v-myc expresses nestin, a cell type-specific marker for neural stem cells. The human neural stem cells expressed both outward and inward K(+) currents with no evidence for Na(+) currents. The density of the outward, delayed rectifying type K(+) current was 1.8 +/- 0.015 nA/pF, and that of the inwardly rectifying K(+) current was 0.37 +/- 0.012 nA/pF (at 30 mM of [K(+)](o)). In order to induce neuronal differentiation of the neural stem cells, a full-length coding region of NeuroD, a neurogenic transcription factor, was transfected into HB1.F3 cells. Introduction of NeuroD induced expression of Na(+) currents with the current density of 0.042 +/- 0.011 nA/pF. The presence of two types of K(+) currents and expression of Na(+) currents induced by NeuroD appear to reflect the characteristic physiological features of human neural stem cells.

Electron cyclotron resonance in a weakly magnetized radio-frequency inductive discharge

The evolution of the electron energy distribution function (EEDF) over a weak magnetic field range is investigated in magnetized radio-frequency (rf) inductive discharges under a collisionless regime where an anomalous skin effect and electron cyclotron resonance (ECR) can occur. A significant change in the low-energy range of the EEDF is found in the ECR condition during the evolution. The observed result reveals the low-energy electrons are efficiently heated by the rf ECR in the presence of the anomalous skin effect. The calculated result of the electron distribution based on kinetic theory is in good agreement with the experiment.

Host cell proteins binding to the encapsidation signal epsilon in hepatitis B virus RNA

The highly conserved encapsidation signal (epsilon) of hepatitis B viral (HBV) pregenomic RNA has been reported as an essential component for encapsidation and protein priming of HBV polymerase. Here, we report that two HBV epsilon RNA-binding host proteins (80 and 43 kDa) and a copurifying protein (100 kDa) were purified and characterized by the combined methods of UV cross-linking analysis with the epsilon RNA and column chromatography. Amino-terminal microsequencing showed that 80- and 43-kDa proteins were identified as the heterodimeric nuclear factor of activated T cells (NF90/NF45) and 100 kDa as a molecular chaperone, the GRP94. The heterodimeric factor interacted preferentially with the upper-bulge region of HBV epsilon RNA helping the HBV polymerase bind the lower-bulge region. Using in vitro protein priming analysis, the initial oligonucleotide of the protein-priming product was deduced as 5'-GAAC-3', which is the complementary sequence of both regions of DR1 and epsilon in the pregenomic RNA. Previously, we also proposed that the GRP94 was associated with HBV polymerase in the human liver cell HepG2. These results suggest that the heterodimeric factor plays an important role in the priming activity of HBV polymerase.

Biodegradation of toluene by a lab-scale biofilter inoculated with Pseudomonas putida DK-1

The biodegradation of toluene by biofiltration inoculated with Pseudomonas putida DK-1 was investigated with variation of the several environmental parameters, such as temperature, bed length, gas flow rate and optimal humidity zone. The optimal temperature range to treat toluene gas was found to be 32-35 degrees C. Increasing the gas flow rate showed an inverse effect on the elimination capacity and the removal efficiency. The optimal gas flow rate was obtained at 65 ml min(-1) from the relation between the removal efficiency and the elimination capacity. The biodegradation rate of the toluene with respect to the bed lengths (3, 6, 9, 12 and 15 cm) increased up to 80 h but was then independent of the bed lengths after 80 h except for the 3 cm bed length. The elimination capacity was improved by about 70% compared with that reported in other literature and was also in agreement with theoretical models.