Genesis of a highly pathogenic and potentially pandemic H5N1 influenza virus in eastern Asia

A highly pathogenic avian influenza virus, H5N1, caused disease outbreaks in poultry in China and seven other east Asian countries between late 2003 and early 2004; the same virus was fatal to humans in Thailand and Vietnam. Here we demonstrate a series of genetic reassortment events traceable to the precursor of the H5N1 viruses that caused the initial human outbreak in Hong Kong in 1997 (refs 2-4) and subsequent avian outbreaks in 2001 and 2002 (refs 5, 6). These events gave rise to a dominant H5N1 genotype (Z) in chickens and ducks that was responsible for the regional outbreak in 2003-04. Our findings indicate that domestic ducks in southern China had a central role in the generation and maintenance of this virus, and that wild birds may have contributed to the increasingly wide spread of the virus in Asia. Our results suggest that H5N1 viruses with pandemic potential have become endemic in the region and are not easily eradicable. These developments pose a threat to public and veterinary health in the region and potentially the world, and suggest that long-term control measures are required.

bcl-XL is the major bcl-x mRNA form expressed during murine development and its product localizes to mitochondria

Most examples of cell death in animals are controlled by a genetic program that is activated within the dying cell. The apoptotic process is further regulated by a set of genes that act as repressors of cell death. Of these, bcl-2 is expressed in a variety of embryonic and postnatal tissues which suggests a critical role for bcl-2 in organogenesis and tissue homeostasis. Surprisingly, mutant mice with targeted disruption of bcl-2 appear normal at birth and complete maturation of lymphoid tissues before succumbing to fulminant lymphopenia and polycystic renal disease by 2–5 weeks of age. This suggests that there may be genes other than bcl-2 that can regulate apoptosis during development. To begin to investigate this possibility, we have cloned and characterized the murine bcl-x gene, whose human counterpart displays striking homology to bcl-2. The predicted murine bcl-xL gene product exhibits a high level of amino acid identity (97%) to its human counterpart. Just like Bcl-2, the murine bcl-xL gene product can act as a dominant inhibitor of cell death upon growth factor withdrawal. In addition, the bulk of the bcl-xL product localizes to the periphery of mitochondria as assessed by a bcl-xL-tag expression system, suggesting that both Bcl-2 and Bcl-xL proteins prevent cell death by a similar mechanism. bcl-xL is the most abundant bcl-x mRNA species expressed in embryonic and adult tissues. The levels of bcl-xL mRNA appear higher than those of bcl-2 during embryonal development and in several adult organs including bone marrow, brain, kidney and thymus. In addition to bcl-xL, we have identified another form of bcl-x mRNA, bcl-x beta, that results from an unspliced bcl-x transcript. bcl-x beta mRNA is expressed in various embryonic and postnatal tissues. Surprisingly, the expression of bcl-xS (a negative regulator of programmed cell death) was undetectable by a sensitive S1-nuclease assay and polymerase chain reaction analysis of mouse tissues. Based on its tissue and developmental patterns of expression, it appears that bcl-x may play an important role in the regulation of cell death during development and tissue homeostasis.

The genesis and evolution of H9N2 influenza viruses in poultry from southern China, 2000 to 2005

H9N2 influenza viruses have become established in terrestrial poultry in different Asian countries over the last 2 decades. Our previous study demonstrated that quail harbor increasingly diverse novel H9N2 reassortants, including both Chicken/Beijing/1/94 (Ck/Bei-like) and Quail/Hong Kong/G1/97 (G1-like) viruses. However, since 1999, the genesis and evolution of H9N2 viruses in different types of poultry have not been investigated systematically. In the present study, H9N2 viruses isolated from chickens, ducks, and other minor poultry species were characterized genetically and antigenically. Our findings demonstrate that Ck/Bei-like H9N2 viruses have been introduced into many different types of poultry in southern China, including quail, partridges, chukar, pheasant, guinea fowl, and domestic ducks, while G1-like viruses were commonly detected in quail, less frequently detected in other minor poultry species, and not detected in chickens and ducks. Genetic analysis revealed 35 genotypes of H9N2 viruses, including 14 novel genotypes that have not been recognized before. Our results also suggested that two-way interspecies transmission exists between different types of poultry. Our study demonstrates that the long-term cocirculation of multiple virus lineages (e.g., H5N1 and H9N2 viruses) in different types of poultry has facilitated the frequent reassortment events that are mostly responsible for the current great genetic diversity in H9N2 and H5N1 influenza viruses in this region. This situation favors the emergence of influenza viruses with pandemic potential.

Potent inhibition of human immunodeficiency virus type 1 replication by an intracellular anti-Rev single-chain antibody

Human immunodeficiency virus type 1 (HIV-1) has a complex life cycle, which has made it a difficult target for conventional therapeutic modalities. A single-chain antibody moiety, directed against the HIV-1 regulatory protein Rev, which rescues unspliced viral RNA from the nucleus of infected cells, has now been developed. This anti-Rev single-chain construct (SFv) consists of both light and heavy chain variable regions of anti-Rev monoclonal antibody, which, when expressed intracellularly within human cells, potently inhibits HIV-1 replication. This intracellular SFv molecule is demonstrated to specifically antagonize Rev function. Thus, intracellular SFv expression, against a retroviral regulatory protein, may be useful as a gene therapeutic approach to combat HIV-1 infections.

Interfacial Assembly and Applications of Functional Mesoporous Materials

Functional mesoporous materials have gained tremendous attention due to their distinctive properties and potential applications. In recent decades, the self-assembly of micelles and framework precursors into mesostructures on the liquid-solid, liquid-liquid, and gas-liquid interface has been explored in the construction of functional mesoporous materials with diverse compositions, morphologies, mesostructures, and pore sizes. Compared with the one-phase solution synthetic approach, the introduction of a two-phase interface in the synthetic system changes self-assembly behaviors between micelles and framework species, leading to the possibility for the on-demand fabrication of unique mesoporous architectures. In addition, controlling the interfacial tension is critical to manipulate the self-assembly process for precise synthesis. In particular, recent breakthroughs based on the concept of the "monomicelles" assembly mechanism are very promising and interesting for the synthesis of functional mesoporous materials with the precise control. In this review, we highlight the synthetic strategies, principles, and interface engineering at the macroscale, microscale, and nanoscale for oriented interfacial assembly of functional mesoporous materials over the past 10 years. The potential applications in various fields, including adsorption, separation, sensors, catalysis, energy storage, solar cells, and biomedicine, are discussed. Finally, we also propose the remaining challenges, possible directions, and opportunities in this field for the future outlook.

Characteristics of Plastic Pollution in the Environment: A Review

Plastics are ubiquitous in the environment and have become a hot topic in academic circles. Extensive studies have focused on analytical methods, source, abundance, transport, fate, degradation of plastics in the environment and threats to natural surroundings, wildlife or even human health. However, characteristics of plastic pollution, which are critical to understand this emerging problem, remain unknown up to now. Here, this paper reviews the major characteristics of plastic pollution in the environment to enhance present understanding of this issue. These characteristics, including diversity, persistence, global issues, combined pollution and threats to organisms and human health, are critically summarized in this work. Further, "plastic cycle" in the environment, namely, aquatic, atmospheric, and terrestrial system, is also discussed in this review. Finally, we highlight current challenges of plastic pollution posed to the public and also recommend the research trends in future work.

Characterization of low-pathogenic H5 subtype influenza viruses from Eurasia: implications for the origin of highly pathogenic H5N1 viruses

Highly pathogenic avian influenza (HPAI) H5N1 viruses are now endemic in many Asian countries, resulting in repeated outbreaks in poultry and increased cases of human infection. The immediate precursor of these HPAI viruses is believed to be A/goose/Guangdong/1/96 (Gs/GD)-like H5N1 HPAI viruses first detected in Guangdong, China, in 1996. From 2000 onwards, many novel reassortant H5N1 influenza viruses or genotypes have emerged in southern China. However, precursors of the Gs/GD-like viruses and their subsequent reassortants have not been fully determined. Here we characterize low-pathogenic avian influenza (LPAI) H5 subtype viruses isolated from poultry and migratory birds in southern China and Europe from the 1970s to the 2000s. Phylogenetic analyses revealed that Gs/GD-like virus was likely derived from an LPAI H5 virus in migratory birds. However, its variants arose from multiple reassortments between Gs/GD-like virus and viruses from migratory birds or with those Eurasian viruses isolated in the 1970s. It is of note that unlike HPAI H5N1 viruses, those recent LPAI H5 viruses have not become established in aquatic or terrestrial poultry. Phylogenetic analyses revealed the dynamic nature of the influenza virus gene pool in Eurasia with repeated transmissions between the eastern and western extremities of the continent. The data also show reassortment between influenza viruses from domestic and migratory birds in this region that has contributed to the expanded diversity of the influenza virus gene pool among poultry in Eurasia.

Establishment of influenza A virus (H6N1) in minor poultry species in southern China

An H6N1 virus, A/teal/Hong Kong/W312/97 (W312), was isolated during the "bird flu" incident in Hong Kong in 1997. Genetic analysis suggested that this virus might be the progenitor of the A/Hong Kong/156/97 (HK/97) H5N1 virus, as seven of eight gene segments of those viruses had a common source. Continuing surveillance in Hong Kong showed that a W312-like virus was prevalent in quail and pheasants in 1999; however, the further development of H6N1 viruses has not been investigated since 2001. Here we report influenza virus surveillance data collected in southern China from 2000 to 2005 that show that H6N1 viruses have become established and endemic in minor poultry species and replicate mainly in the respiratory tract. Phylogenetic analysis indicated that all H6N1 isolates had W312-like hemagglutinin and neuraminidase genes. However, reassortment of internal genes between different subtype virus lineages, including H5N1, H9N2, and other avian viruses, generated multiple novel H6N1 genotypes in different types of poultry. These novel H6N1/N2 viruses are double, triple, or even quadruple reassortants. Reassortment between a W312-like H6N1 virus and an A/quail/Hong Kong/G1/97 (HK/97)-like H9N2 virus simultaneously generated novel H6N2 subtype viruses that were persistent in poultry. Molecular analyses suggest that W312-like viruses may not be the precursors of HK/97 virus but reassortants from an HK/97-like virus and another unidentified H6 subtype virus. These results provide further evidence of the pivotal role of the live poultry market system of southern China in generating increased genetic diversity in influenza viruses in this region.

Abnormalities in whole-brain functional connectivity observed in treatment-naive post-traumatic stress disorder patients following an earthquake

BACKGROUND

Convergent studies have highlighted the dysfunction of the amygdala, prefrontal cortex and hippocampus in post-traumatic stress disorder (PTSD). However, only a few studies have investigated the functional connectivity between brain regions in PTSD patients during the resting state, which may improve our understanding of the neuropathophysiology of PTSD. The aim of this study was to investigate patterns of whole-brain functional connectivity in treatment-naive PTSD patients without co-morbid conditions who experienced the 8.0-magnitude earthquake in the Sichuan province of China.

METHOD

A total of 72 PTSD patients and 86 trauma-exposed non-PTSD controls participated in the resting-state functional magnetic resonance imaging study. All these subjects were recruited from the disaster zone of the 2008 Sichuan earthquake. Functional connectivities between 90 paired brain regions in PTSD patients were compared with those in trauma-exposed non-PTSD controls. Furthermore, Pearson correlation analysis was performed between significantly abnormal connectivities in PTSD patients and their clinician-administered PTSD scale (CAPS) scores.

RESULTS

Compared with non-PTSD controls, PTSD patients showed weaker positive connectivities between the middle prefrontal cortex (mPFC) and the amygdala, hippocampus, parahippocampal gyrus and rectus, as well as between the inferior orbitofrontal cortex and the hippocampus. In addition, PTSD patients showed stronger negative connectivity between the posterior cingulate cortex (PCC) and the insula. The CAPS scores in PTSD patients correlated negatively with the connectivity between the amygdala and the mPFC.

CONCLUSIONS

PTSD patients showed abnormalities in whole-brain functional connectivity, primarily affecting the connectivities between the mPFC and limbic system, and connectivity between the PCC and insula.

Intracellular expression of single-chain variable fragments to inhibit early stages of the viral life cycle by targeting human immunodeficiency virus type 1 integrase

Integration of viral DNA into a chromosome of the infected host cell is required for efficient replication of a retroviral genome, and this reaction is mediated by the virus-encoded enzyme integrase (IN). As IN plays a pivotal role in establishing infection during the early stages of the retroviral life cycle, it is an attractive target for therapeutic intervention. However, the lack of effective antiviral drug therapy against this enzyme has led to the testing of other novel approaches towards its inhibition. In these studies, a panel of anti-human immunodeficiency virus type 1 (anti-HIV-1) IN hybridomas has been used in the construction of single-chain variable antibody fragments (SFvs). The monoclonal antibodies produced by these hybridomas, and derived SFvs, bind to different domains within IN. We now demonstrate that intracellular expression of SFvs which bind to IN catalytic and carboxy-terminal domains results in resistance to productive HIV-1 infection. This inhibition of HIV-1 replication is observed with SFvs localized in either the cytoplasmic or nuclear compartment of the cell. The expression of anti-IN SFvs in human T-lymphocytic cells and peripheral blood mononuclear cells appears to specifically neutralize IN activity prior to integration and, thus, has an effect on the integration process itself. These data support our previous studies with an anti-HIV-1 reverse transcriptase SFv and demonstrate further that intracellularly expressed SFvs can gain access to viral proteins of the HIV-1 preintegration complex. This panel of anti-HIV-1 IN SFvs also provides the tools with which to dissect the molecular mechanism(s) directly involved in integration within HIV-1-infected cells.

Cytosolic phospholipase A2 participates with TNF-alpha in the induction of apoptosis of human macrophages infected with Mycobacterium tuberculosis H37Ra

Macrophage (MPhi) apoptosis, an important innate microbial defense mechanism induced by Mycobacterium tuberculosis (Mtb) H37Ra, depends on the induction of TNF-alpha synthesis. When protein synthesis is blocked, both infection with Mtb and addition of TNF-alpha are required to induce caspase 9 activation, caspase 3 activation and apoptosis. In this study, we show that the second protein synthesis-independent signal involves activation of group IV cytosolic phospholipase A2 (cPLA2). Apoptosis of Mtb-infected MPhi and concomitant arachidonic acid release are abrogated by group IV cPLA2 inhibitors (methyl arachidonyl fluorophosphate and methyl trifluoromethyl ketone), but not by inhibitors of group VI Ca2+-independent (iPLA2; bromoenol lactone) or of secretory low molecular mass PLA2. In MPhi homogenates, the predominant PLA2 activity showed the same inhibitor sensitivity pattern and preferred arachidonic acid over palmitic acid in substrates, also indicating the presence of one or more group IV cPLA2 enzymes. In concordance with these findings, MPhi lysates contained transcripts and protein for group IV cPLA2-alpha and cPLA2-gamma. Importantly, group IV cPLA2 inhibitors significantly reduced MPhi antimycobacterial activity and addition of arachidonic acid, the major product of group IV cPLA2, to infected MPhi treated with cPLA2 inhibitors completely restored the antimycobacterial activity. Importantly, addition of arachidonic acid alone to infected MPhi significantly reduced the mycobacterial burden. These findings indicate that Mtb induces MPhi apoptosis by independent signaling through at least two pathways, TNF-alpha and cPLA2, which are both also critical for antimycobacterial defense of the MPhi.

The tumor suppressor protein p53 strongly alters human immunodeficiency virus type 1 replication

The p53 tumor suppressor gene product, a sequence-specific DNA-binding protein, has been shown to act as a transcriptional activator and repressor both in vitro and in vivo. Consistent with its role in regulating transcription are recent observations that the N-terminal acidic domain of p53 binds directly to the TATA box-binding protein subunit of the general transcription factor, TF IID. It is now demonstrated that wild-type p53 (wt-p53) inhibits human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR)-directed chloramphenicol acetyltransferase activity in a cotransfection assay system. Importantly, this effect of wt-p53 on the HIV-1 LTR was also demonstrated by in vitro transcription assays. In addition, the Sp1 sites and the TATA box of the HIV-1 LTR are demonstrated to be the primary sites involved with p53-induced effects on this viral promoter. The upstream elements of the HIV-1 LTR, including the nuclear factor kappa B (NF-kappa B) binding sites, decrease the p53-induced inhibitory effects on viral transcription. In the presence of the HIV-1 TAR sequence and Tat protein, the HIV-1 LTR also becomes less sensitive to wt-p53-induced inhibition. By using a retroviral vector delivery system, mutant forms of p53 genes were expressed in two HIV-1 latently infected cell lines, ACH-2 and U1. In the ACH-2 cell line, which is now demonstrated to contain an endogenous mutant form of p53 (amino acid 248, Arg to Gln), additional mutant p53 proteins did not alter HIV-1 replication. In U1 cells, which completely lack endogenous p53, overexpression of mutant p53 led to an increase in HIV-1 replication. Thus, these data indicate a possible functional role for wt-p53 and mutant p53 proteins in the control of HIV-1 replication patterns and proviral latency.

Graphene oxide-enzyme hybrid nanoflowers for efficient water soluble dye removal

High efficient enzyme immobilization on carbon based conductive supports could provide wide applications in energy and environmental science. Here, we synthesized a 3D flower-like structured self-assembly hybrid nanocomposite with copper phosphate, laccase, graphite oxide (GO) and carbon nanotubes (CNTs) via a facile one-pot strategy under mild conditions. The prepared nanocomposite exhibited very high enzyme loading and improved laccase activity. During the formation of the nanocomposite, the copper phosphate-laccase petals were interwined by CNTs, and GO nanosheets were further coated on the petal surface. Such a configuration ensured high enzyme loading between the GO sheets and good mass transfer efficiency between immobilized enzyme and substrate, which was confirmed by the kinetics test. We further deposited the immobilized enzyme onto electrodes and observed significantly improved direct electron transfer efficiency. Furthermore, higher dye removal efficiency was observed with the immobilized enzyme. The highly efficient enzyme immobilization strategy provides significant opportunity for its application in bioelectronics and wastewater treatment.

Identification of the progenitors of Indonesian and Vietnamese avian influenza A (H5N1) viruses from southern China

The transmission of highly pathogenic avian influenza H5N1 virus to Southeast Asian countries triggered the first major outbreak and transmission wave in late 2003, accelerating the pandemic threat to the world. Due to the lack of influenza surveillance prior to these outbreaks, the genetic diversity and the transmission pathways of H5N1 viruses from this period remain undefined. To determine the possible source of the wave 1 H5N1 viruses, we recently conducted further sequencing and analysis of samples collected in live-poultry markets from Guangdong, Hunan, and Yunnan in southern China from 2001 to 2004. Phylogenetic analysis of the hemagglutinin and neuraminidase genes of 73 H5N1 isolates from this period revealed a greater genetic diversity in southern China than previously reported. Moreover, results show that eight viruses isolated from Yunnan in 2002 and 2003 were most closely related to the clade 1 virus sublineage from Vietnam, Thailand, and Malaysia, while two viruses from Hunan in 2002 and 2003 were most closely related to viruses from Indonesia (clade 2.1). Further phylogenetic analyses of the six internal genes showed that all 10 of those viruses maintained similar phylogenetic relationships as the surface genes. The 10 progenitor viruses were genotype Z and shared high similarity (>/=99%) with their corresponding descendant viruses in most gene segments. These results suggest a direct transmission link for H5N1 viruses between Yunnan and Vietnam and also between Hunan and Indonesia during 2002 and 2003. Poultry trade may be responsible for virus introduction to Vietnam, while the transmission route from Hunan to Indonesia remains unclear.

Gut microbes in correlation with mood: case study in a closed experimental human life support system

BACKGROUND

Gut microbial community, which may influence our mood, can be shaped by modulating the gut ecosystem through dietary strategies. Understanding the gut-brain correlationship in healthy people is important for maintenance of mental health and prevention of mental illnesses.

METHODS

A case study on the correlation between gut microbial alternation and mood swing of healthy adults was conducted in a closed human life support system during a 105-day experiment. Gut microbial community structures were analyzed using high-throughput sequencing every 2 weeks. A profile of mood states questionnaire was used to record the mood swings. Correlation between gut microbes and mood were identified with partial least squares discrimination analysis.

KEY RESULTS

Microbial community structures in the three healthy adults were strongly correlated with mood states. Bacterial genera Roseburia, Phascolarctobacterium, Lachnospira, and Prevotella had potential positive correlation with positive mood, while genera Faecalibacterium, Bifidobacterium, Bacteroides, Parabacteroides, and Anaerostipes were correlated with negative mood. Among which, Faecalibacterium spp. had the highest abundance, and showed a significant negative correlation with mood.

CONCLUSIONS & INFERENCES

Our results indicated that the composition of microbial community could play a role in emotional change in mentally physically healthy adults.

Self-Assembly of Ir-Based Nanosheets with Ordered Interlayer Space for Enhanced Electrocatalytic Water Oxidation

Iridium (Ir)-based electrocatalysts are widely explored as benchmarks for acidic oxygen evolution reactions (OERs). However, further enhancing their catalytic activity remains challenging due to the difficulty in identifying active species and unfavorable architectures. In this work, we synthesized ultrathin Ir-IrO_x/C nanosheets with ordered interlayer space for enhanced OER by a nanoconfined self-assembly strategy, employing block copolymer formed stable end-merged lamellar micelles. The interlayer distance of the prepared Ir-IrO_x/C nanosheets was well controlled at ∼20 nm and Ir-IrO_x nanoparticles (∼2 nm) were uniformly distributed within the nanosheets. Importantly, the fabricated Ir-IrO_x/C electrocatalysts display one of the lowest overpotential (η) of 198 mV at 10 mA cm^-2_geo during OER in an acid medium, benefiting from their features of mixed-valence states, rich electrophilic oxygen species (O^(II-δ)-), and favorable mesostructured architectures. Both experimental and computational results reveal that the mixed valence and O^(II-δ)- moieties of the 2D mesoporous Ir-IrO_x/C catalysts with a shortened Ir-O^(II-δ)- bond (1.91 Å) is the key active species for the enhancement of OER by balancing the adsorption free energy of oxygen-containing intermediates. This strategy thus opens an avenue for designing high performance 2D ordered mesoporous electrocatalysts through a nanoconfined self-assembly strategy for water oxidation and beyond.

The protein kinases ERK1/2 and their roles in pancreatic beta cells

Extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) activities are modulated in a manner that reflects the secretory demand on beta cells to integrate long- and short-term nutrient sensing information. Our studies have focused on the mechanisms of ERK1/2 activation in beta cells and on the actions of ERK1/2 that regulate beta cell function. Insulin and growth factors regulate ERK1/2 in beta cells in a largely calcium-independent manner. Nutrients and anticipatory hormones, in contrast, activate ERK1/2 in a calcium-dependent manner in these cells. We are exploring the key intermediates in these distinct activation pathways and find that calcineurin is essential for the nutrient pathway but is not essential for the growth factor pathway. Using reporter assays, heterologous reconstitution, electrophoretic mobility shift assays, Northern analysis, Q-PCR and chromatin immunoprecipitation, we have examined several genes that are regulated by ERK1/2, primarily the insulin gene and the apoptotic factor C/EBP-homologous protein (CHOP)-10 (GADD153/DDIT-3), a bZIP protein. ERK1/2-sensitive transcriptional regulators common to these two genes are C/EBP-beta and MafA. The insulin promoter is both positively and negatively regulated by glucose and other nutrients. Exposure to glucose for minutes to hours causes an increase in the rate of insulin gene transcription. In contrast, exposure to elevated glucose for 48 h or more results in inhibition of the insulin gene promoter. Both of these processes depend on ERK1/2 activity. Expression of CHOP is induced by stresses including nutrient deprivation and endoplasmic reticulum stress. CHOP gene expression, especially that regulated by nutrients, is also ERK1/2-dependent in beta cells, These studies support the hypothesis that the genes regulated by ERK1/2 and the mechanisms employed are key to maintaining normal beta cell function.

Targeting human immunodeficiency virus type 1 reverse transcriptase by intracellular expression of single-chain variable fragments to inhibit early stages of the viral life cycle

Novel molecular approaches to inhibit human immunodeficiency virus type 1 (HIV-1) infection have received increasing attention because of the lack of effective antiviral drug therapies in vivo. We now demonstrate that cells can be intracellularly immunized by cytoplasmic expression of single-chain variable antibody fragments (SFv) which bind to the HIV-1 reverse transcriptase (RT) enzyme. The expression of anti-RT SFv in T-lymphocytic cells specifically neutralizes the RT activity in the preintegration stage and affects the reverse transcription process, an early event of the HIV-1 life cycle. Blocking the virus at these early stages dramatically decreased HIV-1 propagation, as well as the HIV-1-induced cytopathic effects in susceptible human T lymphocytes, by impeding the formation of the proviral DNA. These data also demonstrate that intracellular, complete SFvs may gain access to viral proteins of the HIV-1 preintegration complex. These SFvs will provide a tool with which to better understand the molecular mechanisms involved in restricting viral replication in HIV-1-infected cells.

Lactation reduces breast cancer risk in Shandong Province, China

Results from studies of western populations investigating lactation and breast cancer risk have been inconsistent. To examine this issue, the authors conducted a hospital-based case-control study in Shandong Province, China, in 1997-1999. A total of 404 cases and an equal number of controls were included. Detailed information regarding lactation, menstruation, and reproduction was collected through in-person interview. The authors found a significant inverse association between duration of lactation and breast cancer risk. For women who breastfed for more than 24 months per child, the odds ratio was 0.46 (95% confidence interval (CI): 0.27, 0.78) when compared with those who breastfed for 1-6 months per child. A significantly reduced risk of breast cancer was also found for those whose lifetime duration of lactation totaled 73-108 months (odds ratio = 0.47, 95% CI: 0.23, 0.95) and for those who breastfed for > or =109 months (odds ratio = 0.24, 95% CI: 0.11, 0.53). The test for trend was statistically significant for both mean duration of lactation per child (p = 0.02) and lifetime duration of lactation (p = 0.00). Further stratification by menopausal status resulted in the same conclusion. These data suggest that prolonged lactation reduces breast cancer risk.

High-flux, antibacterial ultrafiltration membranes by facile blending with N-halamine grafted halloysite nanotubes

N-Halamine grafted halloysite nanotubes (N-halamine@HNTs) were used as an antibacterial agents to fabricate polyethersulfone (PES) ultrafiltration (UF) hybrid membranes.

A novel SV40-based vector successfully transduces and expresses an alpha 1-antitrypsin ribozyme in a human hepatoma-derived cell line

Alpha 1-antitrypsin (alpha 1AT) deficiency disease is one of the more common hereditary disorders that affects the liver and lung. The liver disease of alpha 1AT deficiency is generally thought to be caused by the accumulation of an abnormal alpha 1AT protein in hepatocytes, whereas the lung disease is thought to be due to a relative lack of the normal protein in the circulation. Therefore, one possible approach to prevent and treat alpha 1AT disease is to both inhibit the expression of the mutated alpha 1AT gene, and to provide a means of synthesizing the normal protein. To do this, we designed specific hammerhead ribozymes that were capable of cleaving the alpha 1AT mRNA at specific sites, and constructed a modified alpha 1AT cDNA not susceptible to ribozyme cleavage. Ribozymes were effective in inhibiting alpha 1AT expression in a human hepatoma cell line using a newly developed simian virus (SV40) vector system. In addition, the hepatoma cell line was stably transduced with a modified alpha 1AT cDNA that was capable of producing wildtype alpha 1AT protein, but was not cleaved by the ribozyme that decreased endogenous alpha 1AT expression. These results suggest that ribozymes can be employed for the specific inhibition for an abnormal alpha 1AT gene product, the first step in designing a gene therapy for the disease. The findings also suggest that the novel SV40-derived vector may represent a fundamental improvement in the gene therapeutic armarmentarium.

Elimination of endogenous aberrant kappa chain transcripts from sp2/0-derived hybridoma cells by specific ribozyme cleavage: utility in genetic therapy of HIV-1 infections

The pooled degenerate-primer polymerase chain reaction (PCR) technology is now widely used in the amplification and cloning of murine hybridoma-specific immunoglobulin gene cDNAs. The design of primers is mainly based on the highly conserved 5' terminus of immunoglobulin gene variable regions and the constant region in the 3' terminus. Of note, most murine hybridoma cell lines are derived from the Sp2/0 cell line, which is demonstrated to express endogenous aberrant kappa chains (abV kappa). This high-level endogenous abV kappa mixes with specific kappa chains in the hybridomas and interferes with the efficiency of the reverse transcriptase (RT)-PCR cloning strategy. In this report, during the cloning of murine anti-human immunodeficiency virus type I (HIV-1) hybridoma immunoglobulin cDNAs, a specific primer-PCR screening system was developed, based on the abV kappa complementarity-defining region (CDR), to eliminate abV kappa-carrying plasmids. Furthermore, an abV kappa sequence-specific derived ribozyme was developed and packaged in a retroviral expression vector system. This abV kappa ribozyme can be transduced into different murine hybridomas, and expressed intracellularly to potently eliminate endogenous abV kappa RNA.