Assessing facilitative responses to a nurse shrub at the community level: the example of Potentilla fruticosa in a sub-alpine grassland of northwest China

Biotic interaction studies have revealed a large discrepancy among experiments in target responses to the effects of neighbours, which may in part be due to both high species-specificity of plant responses and low number of target species used in experiments. Our aim was to assess facilitative responses at the community level and the role of both functional groups and ecological attributes of target species. In a sub-alpine grassland on the eastern Tibet plateau, we assessed growth responses of all species in the community to removal of a dominant shrub. We also measured changes in the main environmental variables. Species responses were analysed by functional group and in relation to their mean regional altitudinal distribution. All significant interactions were positive and affected one-third of the total species richness of the community. All functional groups were facilitated but forbs were less strongly facilitated than in the two other groups. High-alpine species were less strongly facilitated than low-sub-alpine species, but the strength of this relationship was weaker than that reported in previous work. There was evidence of a decrease in extreme temperatures below the canopy of the shrub but no variations in soil moisture. We conclude that the highly stressful conditions induced by the dry continental climate of the eastern Tibet plateau are a main driver of the exclusive dominance of positive interactions. Assessing interactive responses at the community level is likely to provide a useful tool to better understand the role of biotic interactions in community responses to environmental changes.

Erythropoietin prevents reactive oxygen species generation and renal tubular cell apoptosis at high glucose level

Erythropoietin (EPO) can induce a series of cytoprotective effects in many non-hematopoietic tissues through interaction with the erythropoietin receptor (EPOR), but whether EPO can prevent the overproduction of reactive oxygen species (ROS) and apoptosis in diabetes remains unclear. Here, we report that renal tubular cells possess EPOR and that EPO reduces high glucose-induced oxidative stress in renal tubular cells. Further, we found that EPO inhibited high glucose-induced renal tubular cell apoptosis and that this protective effect was dependent on reduction of Bax/caspase-3 expression as well as elevation of Bcl-2 expression. Our results suggest that EPO can inhibit high glucose-induced renal tubular cell apoptosis through direct effect on anti-oxidative stress and that EPOR may play a key role in this process.

Characteristics of young rural Chinese suicides: a psychological autopsy study

BACKGROUND

Patterns of suicide rates in China differ in many ways from those in the West. This study aimed to identify the risk factors characteristic for young rural Chinese suicides.

METHOD

This was a case-control psychological autopsy (PA) study. The samples were suicides and living controls (both aged 15-34 years) from 16 rural counties of China. We interviewed two informants for each suicide and each control with pretested and validated instruments to estimate psychosocial, psychiatric and other risk factors for suicides.

RESULTS

The prevalence of mental disorders was higher among the young Chinese who died by suicide than among the living controls, but was lower than among suicides in the West. Marriage was not a protecting factor for suicide among young rural Chinese women, and never-married women who were involved in relationships were about three times more likely to commit suicide than single women who were unattached. Religion/religiosity was not a protecting factor in Chinese suicide, as it tended to be stronger for suicides than for controls. Impulsivity was significantly higher for suicides than for controls. Psychological strain, resulting from conflicting social values between communist gender equalitarianism and Confucian gender discrimination, was associated significantly with suicide in young rural Chinese women, even after accounting for the role of psychiatric illness.

CONCLUSIONS

Risk factors for suicide in rural China are different from those in the West. Psychological strain plays a role in suicide. Suicide prevention programs in China should incorporate culture-specific considerations.

An experimental study of acute radiation-induced cognitive dysfunction in a young rat model

BACKGROUND AND PURPOSE

Radiation-induced cognitive dysfunction is a common and serious clinical complication after radiation therapy for a brain tumor, but the knowledge of its mechanism is poorly understood. The purpose of this study was to establish a young rat model for acute radiation-induced cognitive dysfunction and associated BBB damage, as well as histopathologic changes.

MATERIALS AND METHODS

Young male rats were randomized into 4 groups to receive irradiation treatments at 300 cGy/min with doses of 0 (sham), 10, 20, and 40 Gy, respectively. Each treatment group was further randomized into 4 subgroups for following up cognitive tests and assessment of their BBB integrity and potential histopathologic changes at 0, 7, 20, and 60 days.

RESULTS

We found that irradiation at 10 Gy failed to induce any significant effects. Irradiation at 20 Gy resulted in a transient impairment of the cognitive functions at 7 and 20 days and returned to normal at 60 days. Irradiation at 40 Gy caused the severest cognitive impairment, which peaked at 7 days, and lasted for at least 60 days. The impaired cognition in both the 20-Gy and 40-Gy-irradiated rats was more or less accompanied with increased brain water content and deteriorated BBB function, though mild histopathologic alternations were only noticed in the 40-Gy-irradiated rats at 20 days.

CONCLUSION

A single-dose exposure at 20 to 40 Gy is sufficient to induce acute brain injury at both cognitive and pathologic levels in young male rats. In addition, morphologic outcomes may not be sensitive enough to reveal all of the pathologic changes, whereas BBB disruption may be an earlier and more sensitive index for acute RE. Therefore, the present model is useful for basic and therapeutic studies of acute RE.

Thin film Ag superlens towards lab-on-a-chip integration

A thin metal film near-field superlens, as originally suggested by Pendry and realized by Fang et al. and Melville et al., is investigated with emphasis on materials suitable for integration on a lab-on-a-chip platform. A chemically resistant cyclo-olefin copolymer (COC), mr-I-T85 from microresist technology, is applied as dielectric matrix/spacer for an Ag thin film superlens. The superlens successfully resolves 80 nm half-pitch gratings when illuminated with UV radiation at a free space wavelength of 365 nm. The superlens design, fabrication and characterization is discussed.

When to conduct a renal impairment study during drug development: US Food and Drug Administration perspective

To optimize drug therapy for individuals, it is critical to understand how various intrinsic (e.g., age, gender, race, genetics, organ impairment) and extrinsic factors (e.g., diet, smoking, concomitantly administered drugs) affect drug exposure and response.(1) Up to now, it has been far easier to discover effects on exposure caused by these factors, and the US Food and Drug Administration (FDA) has published several guidance documents with recommendations on how to evaluate these factors during drug development.

5-HT 3 receptors mediate the time-dependent vagal afferent modulation of nociception during chronic food allergen-sensitized visceral hyperalgesia in rats

Converging lines of evidence demonstrate a vagally mediated antinociceptive pathway in animals undergoing acute visceral insults, the contribution of this system to visceral pain following chronic noxious stimuli is unknown. 5-HT(3) receptor (5-HT(3)Rs) on spinal afferents are crucially involved in nociceptive processing, the role of 5-HT(3)Rs on vagal afferents is unclear. The aim of the present study was to determine the contribution of vagal afferents to visceral nociception in rats undergoing chronic luminal allergen stimulation and whether it involves vagal 5-HT(3)Rs. Sensitized rats received chicken egg albumin (EA, 1 mg mL(-1)) in drinking water for 2 weeks (day 1-14). Visceromotor response (VMR) to colorectal distension [colorectal distension (CRD), 60 mmHg] and the levels of mRNA encoding 5-HT(3)R (including 3A and 3B subunits) in the nodose ganglia (NG) were evaluated on day 2, 4, 8 and 15. Chronic EA challenge induced gradually increased visceral nociception, with a peak on day 15. Subdiaphragmatic vagotomy or functional deafferentation with capsaicin abolished this time-dependent manner, inducing hyperalgesia from day 2, lasting to day 15. Intraluminal infusion of a 5-HT(3)R antagonist (granisetron), whether alone or infused after local mucosa anaesthetic with 1% lidocaine, mimicked the effects of vagotomy. The mRNA levels for 5-HT(3B) or 5-HT(3A) subunit in the NG showed an opposite time-course to that of visceral pain, which increased from day 2, then decreased gradually to levels lower than those of controls. Our results demonstrate a time-dependent vagal afferent modulation of chronic allergen-sensitized visceral hyperalgesia, which may involve a 5-HT(3)R pathway.

Conjugated polymers based on benzo[2,1-b:3,4-b']dithiophene with low-lying highest occupied molecular orbital energy levels for organic photovoltaics

Fusing bithiophene units with a benzo moiety, benzo[2,1-b:3,4-b']dithiophene (BDT), was projected by theoretical calculations to lower the highest occupied molecular orbital (HOMO) energy level of the resulting polymers compared with that of the bithiophene unit, which would enhance the open circuit voltage of bulk heterojunction photovoltaic cells fabricated from BDT-based polymers blended with PCBM. The homopolymer of BDT (HMPBDT) and alternating copolymer of BDT with 2,1,3-benzothiadiazole (PBDT-BT) were therefore synthesized and fully characterized. Both the homopolymer (HMPBDT) and the copolymer (PBDT-BT) were experimentally confirmed to have low HOMO energy levels (-5.70 eV for HMPBDT and -5.34 eV for PBDT-BT). Introducing the acceptor moiety (2,1,3-benzothiadiazole) successfully lowered the optical band gap of the copolymer from 2.31 eV (HMPBDT) to 1.78 eV (PBDT-BT). Bulk heterojunction photovoltaic devices were fabricated from blends of these structurally related polymers with PBCM to investigate the photovoltaic performances. The optimized device of HMPBDT:PCBM (1:3, 180 nm) exhibited an improved open circuit voltage (V(oc)) of 0.76 V, a short circuit current (J(sc)) of 0.34 mA/cm(2), and a fill factor (FF) of 0.40, offering an overall efficiency of 0.10%. The observed large phase separation of the thin film by AFM and the large band gap were accountable for the small current. The optimized device of PBDT-BT:PCBM (1:3, 55 nm) demonstrated a better efficiency of 0.6%, with V(oc) = 0.72 V, J(sc) = 2.06 mA/cm(2), and FF = 0.42. The much improved current was attributed to the lower bandgap and better film morphology. However, the low hole mobility limited the thickness of the PBDT-BT:PCBM film, making inaccessible the thicker film which would utilize more light and enhance the current. Further improvements are expected if the mobility and film morphology can be improved by the new materials design, together with low band gap and low HOMO energy level.

Real-time PCR analysis of the heat-shock response of Acidithiobacillus ferrooxidans ATCC 23270

As one of the most important bioleaching bacterial species, Acidithiobacillus ferrooxidans is subjected to different kinds of environmental stress such as temperature changes, presence of some toxic heavy metals or pH changes, which normally take place in bioleaching operations and may affect the activity of the bacteria. To obtain further knowledge of the protective mechanisms employed by A. ferrooxidans in response to elevated growth temperature, temporal gene expression profiles were examined in cells subjected to heat stress by using real-time PCR. The majority of predicted genes, including those encoding chaperones and heat-shock proteins, were significantly up-regulated (P < 0.05 and the fold change >or= 2.0) over a 25-min period after upshift to the heatshock temperature (from 30 to 42 degrees C) and then decrease to readjust their transcript levels to a new steady state at 42 degrees C. Finally, based on the gene expression data and computational analysis, a putative regulatory site having T-T-T-T-T-T-n-n in the -35 region and n-T-A-T-n-A-T-C in the -10 region with average 19 base pairs separating the two elements was predicted upstream of a number of heat-inducible genes.

Microbial populations in acid mineral bioleaching systems of Tong Shankou Copper Mine, China

AIMS

To understand the composition and structure of microbial communities in different acid mineral bioleaching systems, and to present a more complete picture of microbially mediated acid mine drainage production.

METHODS AND RESULTS

In Tong Shankou Copper Mine, China, two samples (named K1 and K2) from two different sites with bioleaching were studied. A bacterial 16S rDNA library and an archaeal 16S rDNA library of the sample from each site were constructed by 16S rDNA polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP) and sequencing. A total of 18 bacterial representative sequences and 12 archaeal representative sequences were obtained. Phylogenetic analysis indicated that 77.09% of the total bacterial clones were affiliated with Proteobacteria, and 21.22% of the total bacterial clones were closely related to Nitrospira. The rest of the bacterial clones were related to Firmicutes (1.68%). Sequences affiliated with the archaea of the Thermoplasma and Ferroplasma lineages were detected abundantly in the two samples. Unexpectedly, sequences affiliated with Sulfolobales and Methanothermus genera were also detected.

CONCLUSIONS

The molecular studies appear to be consistent with the environmental conditions existing at the sites, which coincides with previous studies. High concentrations of some elements (such as copper, iron and sulfur) seemed to be the key factors resulting in the diverse distribution of typical iron-oxidizing bacteria such as Leptospirillum species and Acidithiobacillus ferrooxidans.

SIGNIFICANCE AND IMPACT OF THE STUDY

Research on micro-organisms present in bioleaching systems especially archaea is not abundant. The acidophiles in the two bioleaching sites obtained from Tong Shankou Copper Mine, China, have not been reported until now. These results may expand our knowledge of the microbial diversity in the acid mineral bioleaching systems.

Photochromism and two-photon luminescence of Ag-TiO(2) granular composite films activated by near infrared ps/fs pulses

We reported photochromism and largely enhanced visible two-photon luminescence (TPL) of Ag-TiO(2) granular composite films by using ps/fs laser at the wavelength of 800 nm. Three types of photochromism spectra were observed when the Ag atom fraction are less than, comparable to and larger than the percolation threshold. The strong surface-plasmon-resonance enhanced visible TPL emissions near Ag(2)O transition band from the photoactivated Ag-TiO(2) samples were also observed. Furthermore, we found that the TPL intensity saturatedly increased while the absorbance at 800 nm exponentially decreased with the same rate as the increasing of photoactivation time, which means that both photochromism and TPL of Ag-TiO(2) composite films are originated from the photo-oxidation of Ag to Ag(+). These observations exhibit the multifunctional features of Ag nanoparticle materials.

UTRN on chromosome 6q24 is mutated in multiple tumors

Though deletion of the long arm of chromosome 6 is one of the most common aberrations in tumors, its targeted gene(s) has not been convincingly identified. Using a functional screening approach, we found that UTRN (which encodes utrophin, a dystrophin-related protein) at 6q24, when expressed in an antisense orientation, induced cellular transformation, consistent with a tumor suppressor role. Northern blot analysis, semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), and gene expression arrays all showed that UTRN expression was downregulated in primary tumors compared with matched normal tissues. Several UTRN neighbor genes were not affected in some tumors with UTRN downregulation, suggesting that UTRN was specifically targeted. RT-PCR, coupled with an in vitro transcription and translation assay, revealed inactivation mutations in 21/62 breast cancers, 4/20 neuroblastomas and 4/15 malignant melanomas. Most of the mutations were deletions involving one or more exons that led to the truncation of utrophin. Splicing errors were found in two cases, and nonsense mutation in one case. Overexpression of a wild-type UTRN in breast cancer cells inhibited tumor cell growth in vitro and reduced their tumor potential in nude mice. Our studies suggest that UTRN is a candidate tumor suppressor gene.

Insulin receptor activation in solitary fibrous tumours

Solitary fibrous tumours (SFTs) are known to overexpress insulin-like growth factor 2 (IGF-2). The down-stream oncogenic pathways of IGF-2, however, are not clear. Here we report uniform activation of the insulin receptor (IR) pathway in SFTs, which are mesenchymal tumours frequently associated with hypoglycaemia. Whereas the IR and its downstream signalling pathways were constitutively activated in SFTs, insulin-like growth factor 1 receptor (IGF-1R) was not expressed in these tumours. We also find that SFT cells secrete IGF-2 and proliferate in serum-free medium, consistent with an IGF-2/IR autocrine loop. The aetiological relevance of IGF-2 is supported by expression of IR-A, the IR isoform with high affinity for IGF-2, in all SFTs. Our studies suggest that IR activation plays an oncogenic role in SFTs.

Dynamics of Photoinduced Electron Transfer in a Molecular Donor−Acceptor Quartet

The electronic structures and dynamics of photoinduced charge separation and recombination in a new donor/acceptor quartet molecule with bis-oligothiophene (BOTH) and bis-perylenediimide (BPDI) blocks attached to a benzene ring were described. Detailed transient spectroscopic studies were carried out on this compound and reference compounds at isolated molecular levels in solution. Two different dynamics of charge separation and recombination associated with two types of donor/acceptor pair conformations in solution were observed. These results were discussed based on Marcus theory and ascribed to both through-bond and through-space electron-transfer processes associated with two different orientations of the acceptors relative to the donor group. This molecular system exhibits a more efficient charge separation than charge recombination processes in both polar and nonpolar organic solvents, indicating that the material is an interesting candidate for photovoltaic studies in solid state.

Clinical study of recombinant adenovirus-p53 (Adp53) combined with hyperthermia in advanced cancer (a report of 15 cases)

The study was to evaluate the efficacy of the Adp53 combined with hyperthermia on advanced cancer. Fifteen patients with advanced cancer were enrolled in this clinical trial. Thirteen patients with recurrent tumours failed in conventional treatments and the two other patients with primary tumour received no treatment before they were enrolled. Recombinant adenovirus-p53 (Adp53) is a E1 substituted replication-incompetent recombinant adenovirus encoding the human wild-type p53 (wtp53) gene. The 15 patients were intra-tumourally injected with Adp53, 1x10(12)vp (virus particle) once a week, with a total of 4-8 times was given. The temperature being set hyperthermia every week 3 days after the injection of Adp53 at 43-44 degrees C using 915 MHz microwave machine for superficial tumour for 1 h or at 42-43 degrees C using 41 MHz radiofrequency machine for deep-seated tumour for 1 h. Among the 15 patients, five concurrently were added with radiotherapy and three were added with cisplatin-based chemotherapy. The treatment achieved CR in two cases, PR in four cases, SD in eight cases and PD in one case and, after the treatment, tumours of two cases disappeared and seven of the other 13 cases (54%) had low-density area (LDA) of more than 50% on CT images in tumours. In the 15 patients, no dose-limiting toxicity and adverse events were noted, except transient fever after Adp53 administration. In conclusion, Adp53 combined with hyperthermia was safe and effective in patients with advanced cancer and p53 gene therapy was potential to thermosensitize in advanced cancer.

Detection of porcine circovirus type 2, porcine parvovirus and porcine pseudorabies virus from pigs with postweaning multisystemic wasting syndrome by multiplex PCR

Multiplex PCR was established to detect porcine circovirus type 2 (PCV-2), porcine parvovirus (PPV) and porcine pseudorabies virus (PRV) and applied to samples from 137 piglets exhibiting clinical signs of postweaning multisystemic wasting syndrome (PMWS). PCV-2 DNA was detected from all samples. Moreover, 43 samples were positive for PPV but negative for PRV; 11 samples were positive for PRV but negative for PPV; and 35 samples were positive both for PPV and PRV. These results suggests that PCV-2 co-infection with PRV and PPV may play an important role in PMWS. Also, multiplex PCR is an appropriate candidate method for diagnosis of PCV-2, PRV and PPV simultaneously in field cases.

Dyads and Triads Containing Perylenetetracarboxylic Diimide and Porphyrin: Efficient Photoinduced Electron Transfer Elicited via Both Excited Singlet States

Synthesis, characterizations, and photophysical properties of new photoactive dyads and triads containing perylenetetracarboxylic diimide (PIm) and porphyrin (free-base porphyrin (H(2)P) and zinc porphyrin (ZnP)), in which both entities were connected with a short ether bond, were examined with the aim of using these systems for molecular photonics. The porphyrin(P)-PIm systems absorbed strongly across the visible region, which greatly matched the solar spectrum. The geometric and electronic structures of the dyads and triads were probed using density function theory method at the B3LYP/3-21G level. It was revealed that the majority of the highest-occupied molecular orbital was located on the porphyrin entity, while the lowest-unoccupied molecular orbitals were entirely on the PIm entity. The excited-state electron-transfer processes were monitored by both steady-state and time-resolved emission as well as transient-absorption techniques in polar solvent benzonitrile. Upon excitation of the P (H(2)P and ZnP) moieties, efficient fluorescence quenching of the P moiety was observed, suggesting that the main quenching paths involved charge separation from the excited singlet porphyrin ((1)P) to the PIm moiety. Upon excitation of the PIm moiety, fluorescence quenching of the (1)PIm moiety was also observed. The nanosecond transience of spectra in near-IR region revealed the charge separation process from the P moieties to the PIm moiety via their excited singlet states. The lifetimes of the charge-separated states were evaluated to be 7-14 ns, depending on the solvent polarity. Photosensitized electron mediation systems were also revealed in the presence of methyl viologen and sacrificial electron donor.

Analysis of lectin receptors in normal nasal mucosa, nasal polyp, inverted papilloma and papillary adenocarcinoma

In order to investigate the changes in glycoprotein structure in the process of cellular differentiation of the nasal mucosa, formalin-fixed, paraffin-embedded biopsy specimens of normal nasal mucosae, nasal polyps, inverted papillomas and papillary adenocarcinomas were analysed by the Avidin Biotin-Peroxidase Complex technique for the demonstration of peanut agglutinin (PNA) receptors, concanavalin ensifomis agglutinin (ConA) receptors, ulex europeaus agglutinin (UEA-I) receptors, wheat germ agglutinin (WGA) receptors, carcino-embryonic antigen (CEA) and keratin. The quantity and distribution of PNA receptors, ConA receptors, UEA-I receptors and CEA were different, in relation to the varying pathological changes. The results suggest that the glycoprotein structure in the cells of the nasal mucosa will change following their differentiation and malignant transformation, which may be helpful in establishing the diagnosis.

Photocurrent Generation in Multilayer Self-Assembly Films Fabricated from Water-Soluble Poly(phenylene vinylene)

A novel, water-soluble, cationic PPV derivative poly[(2,5-bis(3-bromotrimethylammoniopropoxy)-phenylene-1,4-divinylene)-alt-1,4-(2,5-bis(2-(2-hydroxyethoxy)ethoxy))phenylene vinylene] (BH-PPV) has been synthesized by a Heck coupling reaction. Multilayered assemblies of the BH-PPV and the sodium salt of hexa(sulfobutyl)fullerenes (C(60)-HS) were fabricated successfully by an alternate deposition technique. The multilayer structures were studied by UV/Vis spectroscopy, small angle X-ray diffraction, and atomic force microscopy. The photoinduced charge transfer property of the self-assembled multilayer film was also measured by a three-electrode cell technique. A steady and rapid cathodic 5.5 microA cm(-2) photocurrent response was measured as the irradiation of the multilayer film was switched on and off. Importantly, the response of on/off cycling is prompt and reproducible. A possible mechanism for the electron-transfer process is proposed.

Synthesis of organic one-dimensional nanomaterials by solid-phase reaction

The synthesis of anthracene (AN) nanowires and perylene (PY) nanorods on the basis of solid-phase organic reactions under controlled conditions is discussed, and the structures are confirmed by SEM, TEM, and XRD. The dimension-dependent emission properties of the AN nanowires and PY nanorods is observed. This approach is expected to form a new general route for the controlled morphosynthesis of organic molecular materials in restricted dimensions, with controlled size and shape, the solid-state physical properties of which are of great interest. It should have outstanding potential in providing customized 1D nanomaterials for a broad range of applications for molecule devices and nanoscience and is expected to be applicable other functionalized nanomaterials (i.e., organic, inorganic, and polymer).

[Effect of artemether on nucleoside uptake and nucleic acid content in Schistosoma japonicum]

AIM

To observe the effect of artemether (Art) on nucleoside uptake and nucleic acid content in Schistosoma japonicum.

METHODS

RNA and DNA contents of both male and female worms harbored in mice treated intragastrically (i.g.) with Art 300 mg/kg for 24 h or 48 h were determined, respectively. After in vivo drug treatment, the schistosomes recovered were in vitro maintained in drug-free medium containing [3H]adenosine, [5-(3)H] uridine or [methyl-3H]thymidine at a final concentration of 37 MBq/L or 74 MBq/L for 2 h or 4 h, the tritiated nucleoside uptake and incorporation into nucleic acid of schistosomes were measured.

RESULTS

The RNA and DNA contents of female worms recovered from the host 48 h after dosing were markedly decreased by 51.6% and 23.5%, respectively, while the RNA content of male worms showed 42.4% reduction. When the above-mentioned schistosomes were in vitro exposed to the tritiated nucleoside for 2 h or 4 h, apparent decrease in tritiated nucleoside uptake with reduction rates of 35.2%-50.1% was seen in female worms. The incorporation of [methyl-3H]thymidine into the female worm DNA 2 h after incubation was reduced by 71.4% while the incorporation of [3H]adenosine into the female worm RNA and DNA 4 h after incubation was reduced by 65.2% and 50.0%, respectively.

CONCLUSION

Art exhibited an apparent effect on the nucleic acid metabolism in schistosomes, especially in female worms.

[Sequencing of cytochrome C oxidase 1 gene of Ancylostoma duodenale and Necator americanus]

AIM

To identify the genetic diversity between Ancylostoma duodenale and Necator americanus.

METHODS

Mitochondrial cytochrome C oxidase subunit 1 (CO1) gene was amplified from genomic DNA of human hookworms collected from infected patients in Hejiang County, Sichuan Province, and the purified PCR products were directly sequenced by using Licor auto-sequencer.

RESULTS

The PCR products were about 700 bp. Alignment of CO1 gene fragment sequences showed 89.7% similarity between Ancylostoma duodenale and Necator americanus, but still certain nucleotide variations (10.3%) existed.

CONCLUSION

CO1 gene sequence can be used as a marker to identify the two species of human hookworms.

In vitro and in vivo effect of levopraziquantel, dextropraziquantel versus racemic praziquantel on different developmental stages of Schistosoma japonicum

AIM

To compare the antischistosomal effect of racemic praziquantel (Pra) and its enantiomers, levopraziquantel (L-Pra) and dextropraziquantel (D-Pra), on different developmental stages of Schistosoma japonicum.

METHODS

The in vitro effects of the drugs were determined in different stages of schistosomes maintained in RPMI 1640 supplemented with 20% calf serum. In vivo study mice infected with schistosome cercariae were treated intragastrically (ig) with Pra, L-Pra or D-Pra at different intervals after infection. The efficacy of the drugs was evaluated by residual mean worm number.

RESULTS

Based on the degree of tegument damage induced by L-Pra, d28 and d35 schistosomes were most susceptible to L-Pra, while d14 schistosomules being least susceptible. At comparable concentrations of 0.1-1 g/ml, L-Pra was more active than Pra even when the concentration of L-Pra was reduced to one-half of the minimum effective concentration of Pra. At above-mentioned concentrations D-Pra exhibited no apparent in vitro effect on different stages of schistosomes. When infected mice were treated ig with L-Pra, Pra or D-Pra at a single dose of 300 mg/kg or 500 mg/kg, only the former two drugs showed apparent effect on d0, d21, d28 and d35 schistosomes and less or much less effect on d3, d7 and d14 schistosomules. D-Pra only exhibited a negligible effect on d35 adult schistosomes as compared with L-Pra and Pra. When mice infected with d35 adult schistosmes were treated ig with L-Pra 150 mg/kg, the efficacy was similar to that of mice treated with Pra 300 mg/kg.

CONCLUSION

L-Pra is the principal active component against schistosomes in racemic Pra.

Imaging as-grown [60]fullerene nanotubes by template technique

In this contribution we have developed a useful and experimentally easy way to use C60 powder to directly fabricate C60 nanotubes with a mondisperse size distribution and uniform orientation. The structure of C60 nanotubes was confirmed by SEM, TEM, and FT-IR.

Synthesis and characterization of three novel [60]fullerene derivatives toward self-assembled nanoparticles through interaction of hydrogen bonding

[structure: see text] Three novel fullerene derivatives bearing a 2,6-bis(acylamino) pyridine unit as a hydrogen bonding motif displaying a dimerization tendency were synthesized and characterized by the cycloaddition reaction of alkyl azide to [60]fullerene. An SEM image of the dimerization system of compound 1 indicated spherical particles having a mean diameter of 15 nm with a rather narrow size distribution.

Self-assembly and characterization of supramolecular [60]fullerene-containing 2,6-diacylamidopyridine with uracil derivative by hydrogen-bonding interaction

[structure: see text] Novel self-assembly systems of uracil derivatives with organofullerene by a three-point hydrogen-bonding interaction were designed and established. The formation of hydrogen bonding was established by 1H NMR studies in CDCl3.

The potential of artemether for the control of schistosomiasis

Schistosomiasis continues to rank--following malaria--at the second position of the world's parasitic diseases in terms of the extent of endemic areas and the number of infected people. There is yet no vaccine available and the current mainstay of control is chemotherapy with praziquantel used as the drug of choice. In view of concern about the development of tolerance and/or resistance to praziquantel, there is a need for research and development of novel drugs for the prevention and cure of schistosomiasis. Interestingly, derivatives of artemisinin, which are already effectively used in the treatment of malaria, also exhibit antischistosomal properties. Significant advances have been made with artemether, the methyl ether derivative of artemisinin. We review the discovery of the antischistosomal activity of artemether by Chinese scientists two decades ago; the detailed laboratory studies of the susceptibility of, and effect on, the different developmental stages of Schistosoma japonicum, Schistosoma mansoni and Schistosoma haematobium to artemether; the possible mechanism of action and the potential long-term toxicity. Finally, we look at the effect of combined treatment with artemether and praziquantel; and clinical findings thus far obtained from randomised controlled trials with oral artemether for the prevention of patent infections and morbidity. The review intends to create a forum for strategic discussion of how these laboratory and clinical findings could be translated into public health actions. We conclude that artemether--as part of integrated current control measures and adapted to specific socio-ecological and epidemiological settings--has considerable potential to significantly reduce the current burden of schistosomiasis in many parts of the world.

Current progress in the development and use of artemether for chemoprophylaxis of major human schistosome parasites

Human schistosomiasis, a chronic and debilitating parasitic disease of the tropics, is ranked second after malaria in terms of public health importance. At present, there is no vaccine available, and chemotherapy is the cornerstone of schistosomiasis control. Praziquantel is the drug of choice. Oxamniquine has become difficult to obtain and metrifonate has recently been withdrawn from the market. Rapid re-infection following treatment and concern about praziquantel resistance called for the search of novel drugs for prevention and cure of schistosomiasis. Significant progress has been made with artemether, the methyl ether of dihydroartemisinin, already widely used for the treatment of malaria. The present article reviews the literature that led to the development of artemether for chemoprophylaxis in schistosomiasis, and it summarises the experiences so far obtained with its use to control schistosomiasis in different endemic settings. Topics covered include an overview of the global burden of schistosomiasis and approaches for its control; the nature and features of artemisinin and related derivatives, initially discovered as antimalarials, other bioactivities, and their recent discovery of antischistosomal properties; a historic account disclosing the antischistosomal activity of artemether; in vivo assessment of drug susceptibility of different developmental stages of schistosome parasites; artemether-induced pathology evidenced by scanning and transmission electron microscopy; the possible mechanism of action; in vivo studies with combination therapy of artemether and praziquantel; results of randomised controlled clinical trials of oral artemether for the prevention of patent infection and morbidity; and, ultimately the translation of this knowledge into public health action in different endemic settings towards a more integrated approach of schistosomiasis control.

A model of the muscle action potential for describing the leading edge, terminal wave, and slow afterwave

The leading edge, terminal wave, and slow afterwave of the motor-unit action potential (MUAP) are produced by changes in the strength of electrical sources in the muscle fibers rather than by movement of sources. The latencies and shapes of these features are, therefore, determined primarily by the motor-unit (MU) architecture and the intracellular action potential (IAP), rather than by the volume-conduction characteristics of the limb. We present a simple model to explain these relationships. The MUAP is modeled as the convolution of a source function related to the IAP and a weighting function related to the MU architecture. The IAP waveform is modeled as the sum of a spike and a slow repolarization phase. The MU architecture is modeled by assuming that the individual fibers lie along a single equivalent axis but that their action potentials have dispersed initiation and termination times. The model is illustrated by simulating experimentally recorded MUAPs and compound muscle action potentials.

KIT activation is a ubiquitous feature of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract, and they are generally resistant to chemotherapy and radiation therapy. Most GISTs express the KIT receptor tyrosine kinase protein, and a subset of GISTs contain activating mutations within the KIT juxtamembrane region. We evaluated 48 GISTs, including 10 benign, 10 borderline, and 28 malignant cases, to determine whether KIT expression and activation are general properties of these tumors. Immunohistochemical KIT expression was demonstrated in each case. Somatic KIT mutations were found in 44 tumors (92%), of which 34 (71%) had juxtamembrane region mutations. Other GISTs had KIT mutations in the extracellular region (n = 6) and in two different regions in the tyrosine kinase domain (n = 4). Contrary to previous reports, KIT mutations were not identified preferentially in higher-grade tumors: indeed, they were found in each of 10 histologically benign GISTs. Notably, mutations in all KIT domains were associated with high-level KIT activation/phosphorylation, and KIT activation was also demonstrated in the four GISTs that lacked detectable KIT genomic and cDNA mutations. These studies underscore the role of KIT activation in GIST pathogenesis, and they suggest that activated KIT might represent a universal therapeutic target in GISTs.

Sp1 is the major fasl gene activator in abnormal CD4(-)CD8(-)B220(+) T cells of lpr and gld mice

The abnormal CD4(-)CD8(-)TCRalpha beta(+)B220(+) double-negative (DN) T cells that accumulate in lpr and gld mice are refractory to TCR cross-linking and IL-2 stimulation, yet they have an activated phenotype and express a high level of fasl mRNA. Specific binding sites for Sp1, NFAT, Egr, and NF-kappaB have been identified in the promoter region of the fasl gene. To determine the critical factor for fasl gene activation, fasl promoter reporter and mutant constructs were transiently transfected into the abnormal DN T cells. The data demonstrate that the Sp1 binding site is the major response element that regulates fasl promoter activity. Moreover, the abnormal DN T cells contain in their nuclei a high level of Sp1, a low level of NFAT and NF-kappaB, and a very low level of Egr. Ectopic expression of Egr-3 but not Sp1 protein in the abnormal DN T cells enhanced fasl promoter activity, suggesting that the Egr but not Sp1 was limiting for fasl gene activation. Comparison between the abnormal DN T cells and the Sertoli TM4 cells showed a strong correlation between Sp1 expression and fasl mRNA level and FasL function. Our study has identified Sp1 as the major transcription factor responsible for fasl gene activation in the abnormal DN T cells that are defective in signal transduction through TCR and IL-2R, thereby, implicating a novel regulatory pathway for fasl gene activation during the physiological development and elimination of the abnormal DN T cells.

Apoptosis-inducing membrane vesicles. A novel agent with unique properties

The CD95 ligand (FasL) transmembrane protein is found on activated T cells and cells outside the immune system. A well-known turnover process of membrane FasL is mediated by matrix metalloproteinase, which generates soluble FasL (sFasL). Here, we demonstrate that membrane FasL turnover occurs effectively through the release of membrane vesicles. Quantitative analysis indicates that this process is as effective as sFasL release for FasL-3T3 cells but somewhat less effective for FasL-expressing T cells. The apoptosis-inducing membrane vesicles display unique properties not found in FasL-expressing cells and sFasL. Unlike sFasL, vesicle-associated FasL remained bioactive, killing the same panel of targets that are susceptible to FasL-expressing cells. In contrast to FasL-expressing T cells, FasL-mediated killing by vesicles do not involve LFA-1/ICAM interaction and do not depend on de novo protein synthesis. These observations indicate that the release of FasL-bearing vesicles contributes to the turnover of cell-associated FasL, but the impact of the bioactive FasL-expressing vesicles on the function of cell-associated FasL is different from that of sFasL.