Systemic delivery of HK Raf-1 siRNA polyplexes inhibits MDA-MB-435 xenografts

Our past research has focused on identifying an effective carrier composed of histidine and lysine for delivery of nucleic acid into cells. For this purpose, we developed histidine-lysine-rich (HK) polymers with specific sequences and branching. We have found that branched HK polymers in complex with Raf-1 siRNA markedly decreased Raf-1 mRNA and induced apoptosis in cell lines in vitro. The primary focus of the present study was to determine an effective carrier to deliver siRNA systemically to tumor xenografts. After comparing HK:Raf-1 polyplexes for their in-vivo efficacy, we investigated in greater detail whether one of these polymers, H3K(+H)4b, in complex with Raf-1 siRNA, inhibited the growth of MDA-MB-435 xenografts. H3K(+H)4b is a four-branched HK peptide whose predominant repeating sequence within the terminal arm is -HHHK-. After the first tail-vein injection in a mouse model, there was a statistically significant reduction in tumor size between the H3K(+H)4b:Raf-1 siRNA-treated and the control groups (P<0.01). By the third injection, there was nearly a 50% reduction in the Raf-1 siRNA-treated group compared to the control siRNA-treated or -untreated group. Consistent with a significant effect of the HK:Raf-1 polyplex on the tumor, there were marked histological changes, increased apoptosis and fewer vessels in the Raf-1 siRNA-treated group. Raf-1 protein within the tumor was significantly decreased after treatment with the HK:Raf-1 siRNA polyplex compared to the control treatment groups. Despite the striking effect on the tumor by the HK Raf-1 siRNA, there was little evidence of toxicity in normal tissues with this therapy. By harnessing the ability to modify the amino-acid sequence and branching of HK polymers, we expect continued development of HK polymers as in-vivo carriers of siRNA.

The tryptophan synthetase gene TRP1 of Nodulisporium sp.: molecular characterization and its relation to nodulisporic acid A production

Nodulisporic acid A (NAA), an insecticidal indole diterpene, is produced by the fungus Nodulisporium sp. Since indole-3-glycerolphosphate is the precursor of the indole moiety of NAA, it is suggested that the activity of tryptophan synthetase may play a role in NAA biosynthesis. To investigate this hypothesis, the tryptophan synthetase gene TRP1 of Nodulisporium sp. was cloned and characterized. The gene consists of three introns of 146, 68, and 57 bp. The four exons encode a protein of 712 amino acids, the sequence of which is highly homologous to that of other fungal tryptophan synthetase proteins. The transcription initiation site was mapped 66 bp upstream to the ATG, and the polyA tail attachment site is 169 bp downstream to the translation stop codon. Replacement of the N-terminal half of the gene with a hygromycin selection marker yielded mutants with the tryptophan auxotroph/hygromycin-resistance (trp(-)/hyr) phenotype. The TRP1 mutants required a high concentration of tryptophan supplement in solid medium (10 mM) to sustain minimal growth and failed to produce NAA in the production medium (FFL-CAM) supplemented with high concentrations of tryptophan.

Avian influenza A (H5N1) infection in a patient in China, 2006

BACKGROUND

Highly pathogenic avian influenza H5N1 virus has caused increasing human infection in Eurasia since 2004. So far, H5N1 human infection has been associated with over 50% mortality that is partly because of delay of diagnosis and treatment.

OBJECTIVES AND METHODS

Here, we report that an H5N1 influenza virus infected a 31-year-old patient in Shenzhen in June 2006. To identify the possible source of the infection, the human isolate and other H5N1 influenza viruses obtained from poultry and wild birds in southern China during the same period of time were characterized.

RESULTS

Genetic and antigenic analyses revealed that the human H5N1 influenza virus, Shenzhen/406H/06, is of purely avian origin and is most closely related to viruses detected in poultry and wild birds in Hong Kong in early 2006.

CONCLUSIONS

The findings of the present study suggest that the continued endemicity of H5N1 influenza virus in the poultry in southern China increases the chance for introduction of the virus to humans. This highlights the importance of continued surveillance of poultry and wild birds for determining the source for human H5N1 infection.

Species-specific in vitro pharmacological effects of the cannabinoid receptor 2 (CB2) selective ligand AM1241 and its resolved enantiomers

BACKGROUND AND PURPOSE

Racemic (R,S) AM1241 is a cannabinoid receptor 2 (CB(2))-selective aminoalkylindole with antinociceptive efficacy in animal pain models. The purpose of our studies was to provide a characterization of R,S-AM1241 and its resolved enantiomers in vitro and in vivo.

EXPERIMENTAL APPROACH

Competition binding assays were performed using membranes from cell lines expressing recombinant human, rat, and mouse CB(2) receptors. Inhibition of cAMP was assayed using intact CB(2)-expressing cells. A mouse model of visceral pain (para-phenylquinone, PPQ) and a rat model of acute inflammatory pain (carrageenan) were employed to characterize the compounds in vivo.

KEY RESULTS

In cAMP inhibition assays, R,S-AM1241 was found to be an agonist at human CB(2), but an inverse agonist at rat and mouse CB(2) receptors. R-AM1241 bound with more than 40-fold higher affinity than S-AM1241, to all three CB(2) receptors and displayed a functional profile similar to that of the racemate. In contrast, S-AM1241 was an agonist at all three CB(2) receptors. In pain models, S-AM1241 was more efficacious than either R-AM1241 or the racemate. Antagonist blockade demonstrated that the in vivo effects of S-AM1241 were mediated by CB(2) receptors.

CONCLUSIONS AND IMPLICATIONS

These findings constitute the first in vitro functional assessment of R,S-AM1241 at rodent CB(2) receptors and the first characterization of the AM1241 enantiomers in recombinant cell systems and in vivo. The greater antinociceptive efficacy of S-AM1241, the functional CB(2) agonist enantiomer of AM1241, is consistent with previous observations that CB(2) agonists are effective in relief of pain.

The histone deacetylase inhibitors depsipeptide and MS-275, enhance TRAIL gene therapy of LNCaP prostate cancer cells without adverse effects in normal prostate epithelial cells

Gene therapy of cancer using adenovirus as a single treatment modality has met limited success and efforts to enhance therapeutic outcomes have included combination of gene therapy with chemotherapy. The goal of this study was to investigate which chemotherapeutic agents may be suitable for combination with gene therapy of prostate cancer. Using an adenovirus expressing green fluorescent protein (GFP), we determined the effect of cisplatin, gemcitabine, doxorubicin, depsipeptide and MS-275 on adenoviral infectivity and transgene expression in LNCaP cells. We found that the two histone deacetylase inhibitors (HDACi), depsipeptide and MS-275, and to a lesser extent doxorubicin, increased infectivity and transgene expression. However, only the HDACi selectively increased infectivity in LNCaP cells while doxorubicin increased infectivity to a greater extent in normal prostate epithelial cells (PrEC). The increase in infectivity but not transgene expression correlated to increased surface expression of coxsackie and adenovirus receptor (CAR). Increased transgene expression following infection with an adenovirus expressing tumor necrosis factor-related apoptosis inducing ligand (TRAIL) was observed only in LNCaP cells treated with depsipeptide or MS-275. Combination of TRAIL gene therapy with HDACi but not doxorubicin resulted in increased induction of apoptosis in LNCaP cells. In contrast, apoptosis was not enhanced by HDACi in normal PrEC. These results suggest that combination of HDACi with adenoviral TRAIL gene therapy may be a new therapeutic approach for the treatment of prostate cancer that warrants further investigation.

E2F regulates DDB2: consequences for DNA repair in Rb-deficient cells

DDB2, a gene mutated in XPE patients, is involved in global genomic repair especially the repair of cyclobutane pyrimidine dimers (CPDs), and is regulated by p53 in human cells. We show that DDB2 is expressed in mouse tissues and demonstrate, using primary mouse epithelial cells, that mouse DDB2 is regulated by E2F transcription factors. Retinoblastoma (Rb), a tumor suppressor critical for the control of cell cycle progression, regulates E2F activity. Using Cre-Lox technology to delete Rb in primary mouse hepatocytes, we show that DDB2 gene expression increases, leading to elevated DDB2 protein levels. Furthermore, we show that endogenous E2F1 and E2F3 bind to DDB2 promoter and that treatment with E2F1-antisense or E2F1-small interfering RNA (siRNA) decreases DDB2 transcription, demonstrating that E2F1 is a transcriptional regulator for DDB2. This has consequences for global genomic repair: in Rb-null cells, where E2F activity is elevated, global DNA repair is increased and removal of CPDs is more efficient than in wild-type cells. Treatment with DDB2-siRNA decreases DDB2 expression and abolishes the repair phenotype of Rb-null cells. In summary, these results identify a new regulatory pathway for DDB2 by E2F, which does not require but is potentiated by p53, and demonstrate that DDB2 is involved in global repair in mouse epithelial cells.

Surgery and adjuvant radiotherapy vs concurrent chemoradiotherapy in stage III/IV nonmetastatic squamous cell head and neck cancer: a randomised comparison

We compared concurrent combination chemotherapy and radiotherapy with surgery and adjuvant radiotherapy in patients with stage III/IV nonmetastatic squamous cell head and neck cancer. Patients with non-nasopharyngeal and nonsalivary resectable squamous cell head and neck cancer were randomised to receive either surgery followed by adjuvant radiotherapy (60 Gy over 30 fractions) or concurrent combination chemotherapy and radiotherapy (66 Gy in 33 fractions). Combination chemotherapy comprised two cycles of i.v. cisplatin 20 mg m^{− 2} day^{− 1} and i.v. 5-fluorouracil 1000 mg m^{− 2} day^{− 1}, both to run over 96 h given on days 1 and 28 of the radiotherapy. A total of 119 patients were randomised. At a median follow-up of 6 years, there was no significant difference in the 3-year disease-free survival rate between the surgery and concurrent chemoradiotherapy (50 vs 40% respectively). The overall organ preservation rate or avoidance of surgery to primary site was 45%. Those with laryngeal/hypopharyngeal disease subsite had a higher organ-preservation rate than the rest (68 vs 30%). Combination chemotherapy and concurrent irradiation with salvage surgery was not superior to conventional surgery and postoperative radiotherapy for resectable advanced squamous cell head and neck cancer. However, this form of treatment schedule with a view to organ-preservation can be attempted especially for those with laryngeal/hypopharyngeal and possibly oropharyngeal disease subsites.

In vitro efficacy of AdTRAIL gene therapy of bladder cancer is enhanced by trichostatin A-mediated restoration of CAR expression and downregulation of cFLIP and Bcl-XL

Current therapies for bladder cancer are suboptimal and adenoviral gene therapy has been explored as an alternative treatment. In this study, we evaluated the in vitro efficacy of an adenovirus expressing TNF-related apoptosis-inducing ligand (AdTRAIL). At low concentrations of virus, T24 cells were more resistant to AdTRAIL-induced apoptosis than 5637 bladder carcinoma cells. Resistance in T24 cells correlated with poor infectivity and lack of surface expression of coxsackie and adenovirus receptor (CAR). Pretreatment with low concentrations of the histone deacetylase inhibitor trichostatin A, restored CAR expression in T24 cells, which facilitated viral infection and resulted in apoptosis at low concentrations of AdTRAIL. In addition, trichostatin A reduced the expression of Bcl-X(L) and cFLIP resulting in increased sensitivity to recombinant TRAIL. Overexpression of cFLIP inhibited TRAIL-mediated killing in trichostatin A pretreated cells, indicating that downregulation of this antiapoptotic protein is required for sensitization. Therefore, trichostatin A can enhance the efficacy of AdTRAIL by restoring CAR expression and by generating a more pro-apoptotic phenotype that would facilitate bystander activity of TRAIL. Combination of histone deacetylase inhibitors with intravesical AdTRAIL gene therapy may be a novel treatment strategy for bladder cancer.

DNA immunization against very virulent infectious bursal disease virus with VP2-4-3 gene and chicken IL-6 gene

The present study was to investigate the feasibility and efficiency of the DNA vaccine to protect chickens against very virulent infectious bursal disease virus (vvIBDV) infection. A plasmid DNA carrying VP2-4-3 genes of vvIBDV SH95 and a plasmid DNA carrying chicken interleukin-6 (ChIL-6) genes were constructed and designated as pALTER-MAX-VP2-4-3 and pALTER-MAX-ChIL-6 respectively. Several DNA vaccination experiments were performed: 1-week-old chickens were intramuscularly injected with only plasmid pcDNA3-VP2, pALTER-MAX-VP2-4-3 or mixture with pALTER-MAX-ChIL-6. The chickens at 4 weeks old were orally inoculated with vvIBDV SH95. The results showed that immunization with the mixture of pALTER-MAX-VP2-4-3 and pALTER-MAX-ChIL-6 three times conferred protection for 90% of chickens. Enzyme-linked immunosorbent assay (ELISA) antibody titres in chickens immunized together with pALTER-MAX-ChIL-6 were higher than those immunized simply with plasmid pcDNA3-VP2 or pALTER-MAX-VP2-4-3. IBDV was not detected in the bursa of the protected chickens at 8 days after challenge by RT-PCR. The results indicate that protection against vvIBDV can be achieved by using the VP2-4-3 gene of vvIBDV as a DNA vaccine. Furthermore, the simultaneous injection of ChIL-6 plasmid significantly increased the protection after challenge with the very virulent strain.

Structural features of thermozymes

Enzymes synthesized by thermophiles and hyperthermophiles are known as thermozymes. These enzymes are typically thermostable, or resistant to irreversible inactivation at high temperatures, and thermophilic, i.e. optimally active at elevated temperatures between 60 and 125 degrees C. Enzyme thermostability encompasses thermodynamic stability and kinetic stability. Thermodynamic stability is defined by the enzyme's free energy of stabilization (deltaG(stab)) and by its melting temperature (Tm). An enzyme's kinetic stability is often expressed as its halflife (t1/2) at defined temperature. DeltaG(stab) of thermophilic proteins is 5-20 kcal/mol higher than that of mesophilic proteins. The thermostability mechanisms for thermozymes are varied and depend on the enzyme; nevertheless, some common features can be identified as contributing to stability. These features include more interactions (i.e. hydrogen bonds, electrostatic interactions, hydrophobic interactions, disulfide bonds, metal binding) than in less stable enzymes and superior conformational structure (i.e. more rigid, higher packing efficiency, reduced entropy of unfolding, conformational strain release and stability of alpha-helix). Understanding of the stabilizing features will greatly facilitate reengineering of some of the mesozymes to more stable thermozymes.

A gene (pks2) encoding a putative 6-methylsalicylic acid synthase from Glarea lozoyensis

A gene that encodes for a polyketide synthase (PKS) was cloned from the fungus Glarea lozoyensis and characterized. The gene (pks2) consists of four exons interrupted by three introns of 51, 59, and 65 bp, which are clustered at the 5' end. Its predicted product is a 1791-amino-acid protein containing five catalytic motifs typical of fungal PKSs, including a beta-ketosynthase, an acyltransferase, a dehydratase, a beta-ketoacyl reductase, and an acyl carrier region. The gene is transcribed from an initiation site located 375 bp upstream of the translational start codon and extends to a transcriptional termination site 244 bp downstream of the translational stop codon. The gene function is not required for either vegetative growth of G. lozoyensis or for production of pneumocandin, as shown by Agrobacterium-mediated pks2 gene disruption. Previously reported cluster analysis of ketosynthase motifs from 37 fungal polyketide synthases had grouped the Pks2p from G. lozoyensis with PKSs involved in the biosynthesis of 6-methylsalicylic acid. To verify the function of the gene, it was transferred into Aspergillus nidulans under the control of the trpC promoter. 5'-and 3'-RACE experiments confirmed that it was transcribed in the heterologous host, and was associated with the synthesis of a compound identified as 6-methylsalicylic acid by NMR and mass spectrometry. In G. lozoyensis, pks2 is flanked by a gene that encodes a putative drug resistance efflux pump. The Aspergillus pks2 transformants, which were arginine prototrophs, also exhibited precocious pigmentation and accumulated a benzophenone that appeared to be a precursor of emericellin (variecoxanthone B), a known product of A. nidulans. The buildup of the benzophenone may be related to the use of an alternative splice site for the removal of intron 1 of the pks2 transcript in the heterologous host.

BDNF-expressing marrow stromal cells support extensive axonal growth at sites of spinal cord injury

Bone marrow stromal cells (MSCs) constitute a heterogeneous cell layer in the bone marrow, supporting the growth and differentiation of hematopoietic stem cells. Recently, it has been reported that MSCs harbor pluripotent stem cells capable of neural differentiation and that simple treatment of MSCs with chemical inducing agents leads to their rapid transdifferentiation into neural cells. We examined whether native or neurally induced MSCs would reconstitute an axonal growth-promoting milieu after cervical spinal cord injury (SCI), and whether such cells could act as vehicles of growth factor gene delivery to further augment axonal growth. One month after grafting to cystic sites of SCI, native MSCs supported modest growth of host sensory and motor axons. Cells "neurally" induced in vitro did not sustain a neural phenotype in vivo and supported host axonal growth to a degree equal to native MSCs. Transduction of MSCs to overexpress brain-derived neurotrophic factor (BDNF) resulted in a significant increase in the extent and diversity of host axonal growth, enhancing the growth of host serotonergic, coerulospinal, and dorsal column sensory axons. Measurement of neurotrophin production from implanted cells in the lesion site revealed that the grafts naturally contain nerve growth factor (NGF) and neurotrophin-3 (NT-3), and that transduction with BDNF markedly raises levels of BDNF production. Despite the extensive nature of host axonal penetration into the lesion site, functional recovery was not observed on a tape removal or rope-walking task. Thus, MSCs can support host axonal growth after spinal cord injury and are suitable cell types for ex vivo gene delivery. Combination therapy with other experimental approaches will likely be required to achieve axonal growth beyond the lesion site and functional recovery.

Picosecond view of microscopic-scale polarization clusters in paraelectric BaTiO3

The polarization clusters existing in both the ferroelectric and the paraelectric phase of BaTiO3 are directly observed and characterized for the first time by a picosecond soft x-ray laser speckle technique. These dynamic clusters appear continuously across the Curie temperature T(c). The clusters' distance increases approximately linearly with temperature, while their mean size does not change significantly. The polarization exhibits a maximum at a temperature about 5 degrees C above T(c). The clusters' short-range correlation strength diverges as (T-T(c))(-0.41+/-0.02) as temperature decreases toward T(c).

The adsorption of lead and copper from aqueous solution on modified peat-resin particles

Raw peat was modified with sulfuric acid, then mixed modified with resin to prepare the modified peat-resin particles. Using the batch experimental systems, the removal of heavy metals (copper and lead) on the modified peat-resin particles was investigated. The data of the adsorption isotherm could be fitted by the Langmuir equation well. The adsorption rate of heavy metals on modified peat-resin particles was very swift. The removal processes of heavy metals on modified peat-resin particles could be well described by pseudo-second order model. The adsorption rate of lead was affected by the initial heavy metal concentration, initial pH, particle size, agitation speed and particle mass. In the adsorption of heavy metals (lead and copper) on the modified peat-resin particles, ion exchange was the major reaction mechanism. Desorption data showed that the lead adsorbed by modified peat-resin particle could be desorbed by 0.5 N or 1.0 N HNO3. The desorption rate was swift. The experiments indicated that the modified peat-resin particles have great potential for the removal of heavy metals from wastewater.

Primary sarcoma of the distal abdominal aorta: CT angiography findings

Primary aortic angiosarcomas are extremely rare. Clinically and radiographically, they mimic atherosclerosis and atheroembolic disease. For a definitive diagnosis, histologic evaluation of the tumor or of peripheral emboli is required. The imaging findings are frequently nonspecific and in most published cases did not allow a definitive preoperative diagnosis. This is the first report of the computed tomographic angiographic findings of a primary intimal abdominal aortic sarcoma and a review of previously described imaging findings in these tumors.

Identification and serological specificity of a polysaccharide component from Mycoplasma bovis

Whole-cell lysate and proteinase K digest preparations of the Mycoplasma bovis type strain (American Type Culture Collection 25523) were compared using sodium dodecyl sulfate polyacrylamide gel electrophoresis. Coomassie blue staining for protein revealed approximately 50 bands for the lysate but only a single band for the digest. Silver staining for polysaccharide revealed at least 19 bands for the digest. Fourteen monoclonal antibodies (MAbs) were produced using a screening procedure with an M. bovis digest. On immunoblots of digests of four M. bovis strains, an almost identical profile was seen with each strain for all 14 MAbs but differences were evident between strains. One MAb, M1557, was used to analyse 17 M. bovis strains on immunoblots. Ten to 20 bands were observed with 16 of the 17 strains, and differences were apparent among all 16 strains. In an enzyme-linked immunosorbent assay, M1557 reacted with 16 of the 17 M. bovis strains, but did not react with any of 41 non-M. bovis organisms tested. Strong reactions were observed with the MAbs and M. bovis colonies in immunofluorescence. The M. boris polysaccharide and MAbs to this component may be useful for the development of diagnostic assays for this organism.

Inhibitory effect of flowering and early fruit growth on leaf photosynthesis in mango

Carbohydrate and nitrogen contents, chlorophyll fluorescence and gas exchange were measured in leaves from both vegetative and reproductive terminal shoots of 12-year-old flowering mango trees. Reproductive shoot leaves were close to swelling floral buds, inflorescences or panicles bearing set fruits. Leaves close to inflorescences had lower rates of mitochondrial respiration (Rd) and net photosynthesis (Anet), and lower stomatal conductance (gs) and quantum efficiency of photosystem II under actinic light than vegetative shoot leaves. Leaf nitrogen concentration, which decreased from the beginning until the end of flowering, was lower in leaves close to inflorescences than in vegetative shoot leaves. However, these differences and changes were counterbalanced by an increase in leaf mass-to-area ratio so that leaf nitrogen per unit leaf area (Na) remained nearly constant during the whole flowering period, except in leaves close to panicles bearing set fruits. Net CO2 assimilation rate simulated by a biochemical model of leaf photosynthesis (Urban et al. 2003) was much higher than Anet measured at an ambient CO2 partial pressure (Ca) of either 36 or 70 Pa. The overestimation of Anet was more pronounced in leaves close to inflorescences, to panicles bearing set fruits and to reversing inflorescences (characterized by the appearance of leaves in terminal positions on inflorescences) than in vegetative shoot leaves. It is concluded that low Anet in leaves close to inflorescences was probably due neither to changes in Na nor to a decrease in Rubisco activity induced by low gs, but rather to a decrease in electron flow in photosystem II. This decrease was not directly associated with higher starch or soluble sugar contents.

Predicting subcellular localization of proteins using machine-learned classifiers

MOTIVATION

Identifying the destination or localization of proteins is key to understanding their function and facilitating their purification. A number of existing computational prediction methods are based on sequence analysis. However, these methods are limited in scope, accuracy and most particularly breadth of coverage. Rather than using sequence information alone, we have explored the use of database text annotations from homologs and machine learning to substantially improve the prediction of subcellular location.

RESULTS

We have constructed five machine-learning classifiers for predicting subcellular localization of proteins from animals, plants, fungi, Gram-negative bacteria and Gram-positive bacteria, which are 81% accurate for fungi and 92-94% accurate for the other four categories. These are the most accurate subcellular predictors across the widest set of organisms ever published. Our predictors are part of the Proteome Analyst web-service.

Evaluation of four DNA extraction methods for the detection of Mycobacterium avium subsp. paratuberculosis by polymerase chain reaction

Polymerase chain reaction (PCR) has been widely used due to its high specificity, sensitivity, and rapid turn-around time. However, inhibitory factors may be co-extracted with the target nucleic acid that will hinder the performance of PCR. In this study, DNA extraction methods for Mycobacterium avium subsp. paratuberculosis were evaluated including rapid lysis, organic extraction, silica-based and magnetic particle-based (MagaZorb) technologies on bacterial cells, and spiked bovine feces. Efficiency of the extraction was determined by PCR end point titration with primers targeting the insertion sequence, IS900. Results of the end point titrations are identical for bacterial cells and spiked feces. Inhibition was observed in PCR with DNA isolated from spiked feces, and a 1/100 dilution was able to alleviate this problem with DNA extracted by MagaZorb. A 1/1000 dilution was required for the other three methods. MagaZorb proved to be more efficient at removing inhibitory factors and required the least labor and completion time. Further evaluation is required for its utilization in other clinical specimens.

Chimeric RNA-DNA molecular beacon assay for ribonuclease H activity

Current methods to detect and assay ribonuclease H (RNase H) activity are indirect and time-consuming. Here we introduce a direct and sensitive method, based on the fluorescence quenching mechanism of molecular beacons, to assay RNA cleavage in RNA:DNA hybrids. An RNA-DNA chimeric beacon assay for RNase H enzymatic activity was developed. The substrate is a single-stranded RNA-DNA chimeric oligonucleotide labeled with a 5'-fluorescein and a 3'-DABCYL. The fluorophore (fluorescein) of the probe is held in close proximity to the quencher (DABCYL) by the RNA:DNA stem-loop structure. When the RNA sequence of the RNA:DNA hybrid stem is cleaved, the fluorophore is separated from the quencher and fluorescence can be detected as a function of time. Chimeric beacons with different stem lengths and sequences have been surveyed for this assay with E. coli RNase H. We found that the beacon kinetic parameters are in qualitative agreement with previously reported values using more cumbersome assays. This method permits real-time detection of RNase H activity and a convenient approach to RNase H kinetic and mechanistic study.

Neural stem cells constitutively secrete neurotrophic factors and promote extensive host axonal growth after spinal cord injury

Neural stem cells (NSCs) offer the potential to replace lost tissue after nervous system injury. This study investigated whether grafts of NSCs (mouse clone C17.2) could also specifically support host axonal regeneration after spinal cord injury and sought to identify mechanisms underlying such growth. In vitro, prior to grafting, C17.2 NSCs were found for the first time to naturally constitutively secrete significant quantities of several neurotrophic factors by specific ELISA, including nerve growth factor, brain-derived neurotrophic factor, and glial cell line-derived neurotrophic factor. When grafted to cystic dorsal column lesions in the cervical spinal cord of adult rats, C17.2 NSCs supported extensive growth of host axons of known sensitivity to these growth factors when examined 2 weeks later. Quantitative real-time RT-PCR confirmed that grafted stem cells expressed neurotrophic factor genes in vivo. In addition, NSCs were genetically modified to produce neurotrophin-3, which significantly expanded NSC effects on host axons. Notably, overexpression of one growth factor had a reciprocal effect on expression of another factor. Thus, stem cells can promote host neural repair in part by secreting growth factors, and their regeneration-promoting activities can be modified by gene delivery.

[Purification and specific detection of two major Schistosoma gut-associated circulating antigens, CAA and CCA]

AIM

To investigate the specificity differences of the 2 major gut-associated diagnostic circulating molecules in Schistosoma japonicum infection, CAA and CCA, and to obtain sufficient purified material for setting up a standard series in quantitative determinations.

METHODS

Isolation and purification of the two worm fractions from a trichloroacetic acid (TCA) soluble preparation of S. japonicum adult worm antigen (AWAj-TCA) by Mono-Q anion exchange chromatography were performed and the specific reactivity of the eluted fractions by antigen-capture ELISA (specific for CAA or CCA) with reference to affinity purified preparations of S. mansoni CAA and CCA was analysed.

RESULTS

By using an ionic strength gradient, CCA was eluted in two major peaks, an unbound fraction CCA-1, and a major bound fraction CCA-2. Two additional minor peaks, CCA-3 and CCA-4, were eluted at higher ionic strengths. CAA was only detected in a bound fraction, partly overlapping with CCA-3. In the CCA-1 and CCA-2 fractions reactivity was only found in the antigen-capture ELISA using anti-CCA McAbs both for capture and detection. The CAA fraction was predominantly found to be positive in the antigen-capture ELISA using anti-CAA McAbs both for capture and detection. However, when using combinations of anti-CCA and anti-CAA McAbs for capture and detection by ELISA this fraction showed some reactivity.

CONCLUSION

Two CCA fractions contain molecules which bear at least two CCA-epitopes; while the CAA fraction contains molecules which contain at least two CAA-epitopes, and one CCA-epitope.

Sequence and analysis of genomic segment A and B of very virulent infectious bursal disease virus isolated from China

A very virulent infectious bursal disease virus (vvIBDV) field strain, named SH95, was identified and characterized from flocks with vaccination failure in Shanghai. The use of random primer and a reverse transcriptase lacking RNase-H activity produced full-length cDNA copies of the viral genomic A and B segments of SH95. The 3259 base pairs (bp) of segment A and 2827 bp of segment B were amplified by long and accurate PCR in a single step, then successfully cloned and sequenced. There were five to 27 amino acid substitutions compared with other IBDV strains within the segment A polyprotein (of these, three are unique) and about nine to 38 amino acid substitutions within VP1 (of which, four are unique). The comparison of sequences encoding the polyprotein showed that vvIBDV SH95 was most closely related to Asiatic vvIBDVs, which formed a closely related group clearly distinguishable from other classical strains of IBDV. Phylogenetic analysis suggested that vvIBDV SH95 and some other Asiatic vvIBDVs were derived from similar origin. But the topology tree performed on segment B was quite different from that performed on segment A, indicating that a genetic reassortment had played an important role in the emergence of vvIBDV SH95.

Efficient disruption of a polyketide synthase gene ( pks1) required for melanin synthesis through Agrobacterium-mediated transformation of Glarea lozoyensis

Glarea lozoyensis produces pneumocandin B(0), a potent inhibitor of fungal glucan synthesis. This industrially important filamentous fungus is slow-growing, is very darkly pigmented, and has not been easy to manipulate genetically. Using a PCR strategy to survey the G. lozoyensis genome for polyketide synthase (PKS) genes, we have identified pks1, a gene that consists of five exons interrupted by four introns of 56, 400, 50 and 341 bp. It encodes a 2124-amino acid protein with five catalytic modules: ketosynthase, acyltransferase, two acyl carrier sites, and thioesterase/Claisen cyclase. The transcriptional initiation and termination sites were found 43 bp upstream of the translational start codon and 295 bp downstream of the translational stop codon, respectively. Cluster analysis of 37 fungal ketosynthase modules grouped the Pks1p with PKSs involved in the biosynthesis of 1,8-dihydroxynaphthalene melanin. Disruption of pks1 yielded knockout mutants that displayed an albino phenotype, suggesting that pks1 encodes a tetrahydroxynaphthalene synthase. Gene replacement was achieved by Agrobacterium-mediated transformation, which proved to be simple and efficient. Loss of pigmentation occurred in more than half the transformants, and examination of six non-pigmented transformants showed that the functional genomic copy of the pks1 gene had been replaced by the disruption cassette in each case. A putative 1215-bp ORF (dsg) devoid of introns was present downstream from pks1. BLAST analysis of the 405-amino acid sequence of its predicted product showed a high degree of similarity with Zn(II)(2)Cys(6) binuclear cluster DNA-binding proteins, a class of fungal transcription factors involved in the regulation of polyketide production and other pathways.

[Comparative observation on the efficacy of several test/probe systems for detecting schistosome circulating antigen]

AIM

To compare the efficacy of 5 test/probe systems for the detecting of schistosomal circulation antigen (SCA) in sera from infected rabbits.

METHODS

Nine rabbits were infected with monosexual cercariae (either male or female), 7 rabbits were infected with bisexual cercariae as controls. Blood samples were collected periodically post infection (p.i). 15 rabbits were infected each with 250 bisexual cercaria and divided into 3 groups, 2 groups were treated with allyl thiourea (295-590 mg/kg) from 19 d or 46 d respectively, to inhibit their egg formation. One untreated group was used as control. Blood samples were collected weekly until 8 wk post infection. SCA detecting methods include (1) dot-ELISA/McAb anti-surface membrane antigen of adult worms (8SE4), (2) dot-ELISA/McAb anti-CCA (3D10), (3) Sandwich dot-ELISA/McAb anti-egg antigen (MG2), (4) Sandwich-ELISA/McAb anti-egg antigen (2H10), (5) Sandwich-ELISA/McAb anti-CAA (1B10).

RESULTS

Using method (1) all of the 18 rabbits infected with monosexual cercariae were negative. Using method (2) only 1 rabbit harboured 133 male worms showed positive. Using method (5) no SCA were detected in sera from female cercariae-infected rabbits but 3 out of 9 male cercariae-infected rabbits showed positive reaction. SCA detecting results from rabbits treated with allyl thiourea: both method (1) and (3) showed negative in rabbits treated from 19 d (p.i.) but all gave positive reaction in 6-7 wk in rabbits treated from 46 d (p.i.). There were all negative detected by using method (4) and all positive at 6 wk (p.i.) detected by method (5) in rabbits of 3 groups whether treated or non-treated.

CONCLUSION

Various test/probe systems have different efficacy in detecting SCA but (5) of the methods (1)(2) tests/probe systems could not detect SCA in rabbits with single female cercariae infection. From the egg formation inhibition study, the SCA detected by McAb 8SE4 dot-ELISA might be related to egg maturation. Whether the surface membrane antigen of adult worm has common antigenic component with egg antigen remains to be studied.

Picosecond snapshot of the speckles from ferroelectric BaTiO3 by means of x-ray lasers

A picosecond x-ray laser speckle has been conducted to study the dynamics of a disordered surface domain structure (BaTiO3 with 90 degrees c/a domains) as a function of temperature for the first time. The transient surface structures induced by ferroelectric domains decrease as temperature increases towards the Curie temperature T(c) and completely disappear above T(c). The dramatic change of the spatial configuration of the c/a domains was observed to occur from a temperature 2 degrees C below T(c), near which the average correlated domain size at equilibrium decreases as (T(c)-T)(0.37+/-0.02).

Prevalence of hearing disorders in Singapore military conscripts: a role for routine audiometry screening?

AIM

To determine the prevalence of hearing disorders in Singapore military conscripts and describe the profile of hearing loss and associated risk factors.

METHODS

Population-based descriptive analysis of randomised cohort of 818 Singapore military conscripts presenting for medical examination, using self-administered questionnaire and pure tone audiometry performed for both ears. Main outcome measures are prevalence rate of hearing loss and relative risk of hearing loss by demographic factors and surrogates for noise exposure.

RESULTS

Prevalence of hearing loss was 36.7 per 1,000 (95% CI 24.8, 51.9). Of 30 subjects with hearing loss, 19 (63.3%) had loss at high frequency, 7 (23.3%) at low frequency, and 4 (13.4%) in both ranges. Hearing loss was unilateral in 17 (56.7%) subjects and bilateral in 13 (43.3%). Relative risk of hearing loss did not differ by age group, education level, race or frequency of personal stereo use. Relative risk of hearing loss is higher in subjects with frequent discotheque visits compared to those who never do so (RR = 2.72, 95%CI 1.09, 6.76).

CONCLUSION

The high prevalence of hearing loss in Singapore military conscripts points to the need for routine audiometry screening prior to enlistment. This will be useful in assigning military vocations, in clinical case management, and for assessing cases of noise-induced hearing loss attributable to military service.

Correct identification of polychlorinated biphenyls in temperature-programmed GC with ECD detection

A method has been developed for peak identification of PCBs in GC with ECD detection under different temperature programs and isothermal conditions on two commonly used columns (DB-5 and DB-1701). This was achieved by means of accurate calibration of retention times based on the concept of the relative retention index P (i) and retention times of the selected PCB internal standards. The P (i) was calculated from the predicted retention times with the database of the retention parameters (A, B) and the migration equations. Through comparison of the calibrated and experimental retention times of PCBs in technical samples, it was shown that the developed method was effective for correct PCB comprehensive, quantitative, congener-specific (CQCS) analyses.

Influence of water treatment residuals on phosphorus solubility and leaching

Laboratory and greenhouse studies compared the ability of water treatment residuals (WTRs) to alter P solubility and leaching in Immokalee sandy soil (sandy, siliceous, hyperthermic Arenic Alaquod) amended with biosolids and triple superphosphate (TSP). Aluminum sulfate (Al-WTR) and ferric sulfate (Fe-WTR) coagulation residuals, a lime softening residual (Ca-WTR) produced during hardness removal, and pure hematite were examined. In equilibration studies, the ability to reduce soluble P followed the order Al-WTR > Ca-WTR = Fe-WTR >> hematite. Differences in the P-fixing capacity of the sesquioxide-dominated materials (Al-WTR, Fe-WTR, hematite) were attributed to their varying reactive Fe- and Al-hydrous oxide contents as measured by oxalate extraction. Leachate P was monitored from greenhouse columns where bahiagrass (Paspalum notatum Flugge) was grown on Immokalee soil amended with biosolids or TSP at an equivalent rate of 224 kg P ha(-1) and WTRs at 2.5% (56 Mg ha(-1)). In the absence of WTRs, 21% of TSP and 11% of Largo cake biosolids total phosphorus (PT) leached over 4 mo. With co-applied WTRs, losses from TSP columns were reduced to 3.5% (Fe-WTR), 2.5% (Ca-WTR), and <1% (Al-WTR) of applied P. For the Largo biosolids treatments all WTRs retarded downward P flux such that leachate P was not statistically different than for control (soil only) columns. The phosphorus saturation index (PSI = [Pox]/ [Al(ox) + Fe(ox)], where Pox, Al, and Fe(ox) are oxalate-extractable P, Al, and Fe, respectively) based on a simple oxalate extraction of the WTR and biosolids is potentially useful for determining WTR application rates for controlled reduction of P in drainage when biosolids are applied to low P-sorbing soils.

Genotype and allele frequency of the 27-bp tandem repeat polymorphism in the endothelial nitric oxide synthase gene in Chinese population

Genotype and allele frequency of the polymorphic 27-bp repeat, a variable number of tandem repeats (VNTR) located in intron 4 of the endothelial nitric oxide synthase gene, were analyzed in 316 healthy Chinese individuals. Four genotypes, namely 6/5-repeats heterozygous, 5/5-repeats homozygous, 5/4-repeats heterozygous and 4/4-repeats homozygous, were identified. Both observed genotype and allele frequencies of this VNTR in Chinese were similar to those of Japanese, while the 4/4-repeats genotype differed significantly from that of Caucasians in Spain, and all ones did from those of African-American in United States.

A new siglec family member, siglec-10, is expressed in cells of the immune system and has signaling properties similar to CD33

The siglecs (sialic acid-binding Ig-like lectins) are a distinct subset of the Ig superfamily with adhesion-molecule-like structure. We describe here a novel member of the siglec protein family that shares a similar structure including five Ig-like domains, a transmembrane domain, and a cytoplasmic tail containing two ITIM-signaling motifs. Siglec-10 was identified through database mining of an asthmatic eosinophil EST library. Using the Stanford G3 radiation hybrid panel we were able to localize the genomic sequence of siglec-10 within the cluster of genes on chromosome 19q13.3-4 that encode other siglec family members. We have demonstrated that siglec-10 is an immune system-restricted membrane-bound protein that is highly expressed in peripheral blood leukocytes as demonstrated by Northern, RT-PCR and flow cytometry. Binding assays determined that the extracellular domain of siglec-10 was capable of binding to peripheral blood leukocytes. The cytoplasmic tail of siglec-10 contains four tyrosines, two of which are embedded in ITIM-signaling motifs (Y597 and Y667) and are likely involved in intracellular signaling. The ability of tyrosine kinases to phosphorylate the cytoplasmic tyrosines was evaluated by kinase assay using wild-type siglec-10 cytoplasmic domain and Y-->F mutants. The majority of the phosphorylation could be attributed to Y597 andY667. Further experiments with cell extracts suggest that SHP-1 interacts with Y667 and SHP-2 interacts with Y667 in addition to another tyrosine. This is very similar to CD33, which also binds the phosphatases SHP-1 and SHP-2, therefore siglec-10, as CD33, may be characterized as an inhibitory receptor.

B7H costimulates clonal expansion of, and cognate destruction of tumor cells by, CD8(+) T lymphocytes in vivo

B7H/B7RP (hereby called B7H) is a new member of the B7 family of costimulatory molecules and interacts with inducible costimulatory molecule (ICOS). Its function for CD8 T cells has not been reported. We report here that expression of B7H on the tumor cells reduced tumorigenicity and induced immunity to subsequent challenge with parental tumor cells. The immune protection correlates with an enhanced cytotoxic T lymphocyte (CTL) response against P1A, the major tumor antigen expressed in the J558 tumor. To understand the mechanism of immune protection, we adoptively transferred transgenic T cells specific for tumor antigen P1A into mice that bore P1A-expressing tumors. We found that while the transgenic T cells divided faster in mice bearing the B7H(+) tumors, optimal B7H-induced clonal expansion of P1CTL required costimulation by B7-1 and B7-2 on the endogenous host antigen-presenting cells (APCs). Interestingly, when B7H(+) and B7H(-) tumors were coinjected, P1CTL selectively eliminated the B7H(+) tumor cells. Moreover, B7H expressed on the tumor cells made them highly susceptible to destruction by CTL in vivo, even if the CTL was administrated into mice with large tumor burdens. Tumors that recurred in the P1CTL-treated mice lost transfected B7H and/or H-2L(d), the class I molecule that presents the P1A peptide. Taken together, our results reveal that B7H costimulates clonal expansion of, and cognate destruction by CD8(+) T lymphocytes in vivo.

Testosterone, 7-benzyloxyquinoline, and 7-benzyloxy-4-trifluoromethyl-coumarin bind to different domains within the active site of cytochrome P450 3A4

Testosterone, 7-benzyloxyquinoline, and 7-benzyloxy-4-trifluoromethyl-coumarin, marker substrates for cytochrome P450 3A4 are commonly used within the pharmaceutical industry to screen new chemical entities as inhibitors of CYP3A4 in a high-throughput manner to predict the potential for drug-drug interactions. However, it has been observed that inhibition data obtained with a given CYP3A4 probe substrate may not correlate well with results from a different probe. As a consequence, the choice of the probe compound becomes an important consideration in such screens. In the present study, kinetic interactions between either two of the above three substrates were evaluated, and three-dimensional nonlinear regression analysis was performed to understand the kinetic mechanisms of drug interaction. Our results demonstrate that the kinetic interaction between each pair of substrates does not appear to be competitive and that the interactions are characterized by an unchanged or a decrease in both apparent K(m) (a = 0.21-0.72, a change of K(m) in the absence of the effector) and V(max) (alpha and beta = 0.09-0.75, changes of V(max) in the absence of the effector). These data suggest that 1) the three substrates bind to different domains; 2) at least two substrates can coexist in the active site of CYP3A4; and 3) the two bound substrates interact kinetically with each other (e.g., through steric hindrance), thereby leading to a change in both apparent kinetic parameters and partial inhibition. Selection of multiple substrates, which are shown not to be competitive, is necessary to accurately predict CYP3A4 inhibition and the potential for drug-drug interaction.

Nuclear reconstitution of plant (Orychophragmus violaceus) demembranated sperm in cell-free extracts from animal (Xenopus laevis) eggs

Cell-free extracts from animal Xenopus laevis egg could induce chromatin decondensation and pronuclear formation from demembranated plant (Orychophragmus violaceus) sperm. When incubated with Xenopus egg extracts, the demembranated sperm began to swell and then gradually decondensed. The assembly of the nuclear envelope in the reconstituted nuclei was visualized by means of electron microscopy and fluorescence microscopy. Membrane vesicles fused to form the double envelope around the periphery of the decondensed chromatin. The morphology of the newly formed nuclei, with a double membrane, was similar to that of nuclei after fertilization. The electron micrograph of the whole-mount prepared nuclear matrix--lamina showed the reconstituted nucleus to be filled with a dense network.

Nuclear assembly of demembranated Xenopus sperm in plant cell-free extracts from Nicotiana ovules

The cell-free preparation derived from Nicotiana tabaccum ovules induced chromatin decondensation and pronuclear formation from demembranated Xenopus laevis sperm nuclei. Fluorescent microscope and phase-contrast microscope visualization of assembly intermediates indicated that 95.6% of X. leavis sperm changed their tadpole-like shape to circular shape or elliptical shape after over 1.5 h of incubation. Transmission electron microscope visualization showed that nuclear membrane was assembled around the periphery of the dispersed chromatin. Nuclear envelope of most reassembled nuclei was composed of a double membrane inlaid with a little single membrane. Nucleosome assembly was verified by means of micrococcal nuclease digestion. After 2 to 5 h of incubation, digestion of the product of nuclear assembly with micrococcal nuclease produced at least six nucleosome fragments of about 250 bp each.

[A century of developmental history of laparoscopic surgery]

Till the year 2001, the development of laparoscopic surgery will have gone through a total of one hundred years. Laparoscopic surgery has made a great progress during the last more than a decade. In retrospect its history, the development of laparoscopic surgery underwent three main eras, viz. diagnostic laparoscopy, operative laparoscopy and the modern laparoscopy era. Although the laparoscopic technology started rather late in China, it develops very quickly. Along with the development of high -- tech, laparoscopic surgery will have a promising future.

Neurotrophism without neurotropism: BDNF promotes survival but not growth of lesioned corticospinal neurons

Neurotrophic factors exert many effects on the intact and lesioned adult central nervous system (CNS). Among these effects are prevention of neuronal death (neurotrophism) and promotion of axonal growth (neurotropism) after injury. To date, however, it has not been established whether survival and axonal growth functions of neurotrophins can be independently modulated in injured adult neurons in vivo. To address this question, the ability of brain-derived neurotrophic factor (BDNF) to influence corticospinal motor neuronal survival and axonal growth was examined in two injury paradigms. In the first paradigm, a survival assay, adult Fischer 344 rats underwent subcortical lesions followed by grafts to the lesion cavity of syngenic fibroblasts genetically modified to secrete high amounts BDNF or, in control subjects, the reporter gene green fluorescent protein. In control subjects, only 36.2 +/- 7.0% of the retrogradely labeled corticospinal neurons survived the lesion, whereas 89.8 +/- 5.9% (P < 0.001) of the corticospinal neurons survived in animals that received BDNF-secreting grafts. However, in an axonal growth assay, BDNF-secreting cell grafts that were placed into either subcortical lesion sites or sites of thoracic spinal cord injury failed to elicit corticospinal axonal growth. Despite this lack of a neurotropic effect on lesioned corticospinal axons, BDNF-secreting cell grafts placed in the injured spinal cord significantly augmented the growth of other types of axons, including local motor, sensory, and coerulospinal axons. Immunolabeling for tyrosine kinase B (trkB) demonstrated that BDNF receptors were present on corticospinal neuronal somata and apical dendrites but were not detected on their projecting axons. Thus, single classes of neurons in the adult CNS appear to exhibit disparate survival and growth sensitivity to neurotrophic factors, potentially attributable at least in part to differential trafficking of neurotrophin receptors. The possibility of tropic/trophic divergence must be considered when designing strategies to promote CNS recovery from injury.

[Significance of prospective follow-up cohort study in diagnosis and treatment of primary hepatic cancer among HBsAg carriers]

OBJECTIVE

To investigate the clinical and etiological significance of regular follow-up study of cohort of HBsAg carriers in diagnosis and treatment of primary hepatic cancer (PHC).

METHODS

A prospective follow-up study lasting 8 years and 3 months was conducted among 744 HBsAg positive persons and 895 HBsAg negative persons in Qidong, Jiangsu Province, a high incidence area of PHC. A serum store was established. Survey of detailed individual history was made.

RESULTS

(1) The year-incidence rate of PHC was significantly higher in the HBsAg group (177.29/100,000) than in the HBsAg group (69.53/100,000, RR = 16.93) (P < 0.01). There was no significance difference in the incidence rates of other tumors between these two groups (P > 0.05). (2) The average time between the onset of hepatitis and the diagnosis of PHC was 14.5 years with a median time of 13 years. The average time between the diagnosis of cirrhosis and the diagnosis of PHC was 6.4 years with a median time of 5.5. year. (3) Bad economic condition, longer history of drinking, longer smoking history, history of hepatitis and chronic gastrointestinal diseases, and family of PHC could be found more frequently in the PHC group than in the non-PHC group (P < 0.001). There was no difference in other personal habit, personal history, disease history, and family hirsute between these two groups (P > 0.05). (4) The tumor resection rate (16.44%) and one-year survival rate (31.51%) were significantly higher among the PHC patients in the prospective cohort than those in the PHC patients diagnosed and treated individually in local hospitals (8.7% and 9.7% respectively, P < 0.01).

CONCLUSION

HBV is closely correlated with PHC. Males, persons aged between 20 and 60, HBsAg positive persons and/or persons with hepatitis history and family hepatitis history are high risk population for PHC. Regular follow-up of these populations by AFP examination combined with B-ultrasonography contributes to early diagnosis of PHC and significantly improves the curative effect.