Bone Morphogenic Proteins Are Immunoregulatory Cytokines Controlling FOXP3+ Treg Cells

Bone morphogenic proteins (BMPs) are members of the transforming growth factor β (TGF-β) cytokine family promoting differentiation, homeostasis, and self-renewal of multiple tissues. We show that signaling through the bone morphogenic protein receptor 1α (BMPR1α) sustains expression of FOXP3 in T_reg cells in peripheral lymphoid tissues. BMPR1α signaling promotes molecular circuits supporting acquisition and preservation of T_reg cell phenotype and inhibiting differentiation of pro-inflammatory effector Th1/Th17 CD4⁺ T cell. Mechanistically, increased expression of KDM6B (JMJD3) histone demethylase, an antagonist of the polycomb repressive complex 2, underlies lineage-specific changes of T cell phenotypes associated with abrogation of BMPR1α signaling. These results reveal that BMPs are immunoregulatory cytokines mediating maturation and stability of peripheral FOXP3⁺ regulatory T cells (T_reg cells) and controlling generation of iT_reg cells. Thus, we establish that BMPs, a large cytokine family, are an essential link between stromal tissues and the adaptive immune system involved in sustaining tissue homeostasis by promoting immunological tolerance.

TGF-β-mediated enhancement of TH17 cell generation is inhibited by bone morphogenetic protein receptor 1α signaling

The cytokines of the transforming growth factor-β (TGF-β) family promote the growth and differentiation of multiple tissues, but the role of only the founding member, TGF-β, in regulating the immune responses has been extensively studied. TGF-β is critical to prevent the spontaneous activation of self-reactive T cells and sustain immune homeostasis. In contrast, in the presence of proinflammatory cytokines, TGF-β promotes the differentiation of effector T helper 17 (TH17) cells. Abrogating TGF-β receptor signaling prevents the development of interleukin-17 (IL-17)-secreting cells and protects mice from TH17 cell-mediated autoimmunity. We found that the receptor of another member of TGF-β family, bone morphogenetic protein receptor 1α (BMPR1α), regulates T helper cell activation. We found that the differentiation of TH17 cells from naive CD4+ T cells was inhibited in the presence of BMPs. Abrogation of BMPR1α signaling during CD4+ T cell activation induced a developmental program that led to the generation of inflammatory effector cells expressing large amounts of IL-17, IFN-γ, and TNF family cytokines and transcription factors defining the TH17 cell lineage. We found that TGF-β and BMPs cooperated to establish effector cell functions and the cytokine profile of activated CD4+ T cells. Together, our data provide insight into the immunoregulatory function of BMPs.

Single gold nanoparticle plasmonic spectroscopy for study of chemical-dependent efflux function of single ABC transporters of single live Bacillus subtilis cells

ATP-binding cassette (ABC) membrane transporters serve as self-defense transport apparatus in many living organisms and they can selectively extrude a wide variety of substrates, leading to multidrug resistance (MDR). The detailed molecular mechanisms remain elusive. Single nanoparticle plasmonic spectroscopy highly depends upon their sizes, shapes, chemical and surface properties. In our previous studies, we have used the size-dependent plasmonic spectra of single silver nanoparticles (Ag NPs) to study the real-time efflux kinetics of the ABC (BmrA) transporter and MexAB-OprM transporter in single live cells (Gram-positive and Gram-negative bacterium), respectively. In this study, we prepared and used purified, biocompatible and stable (non-aggregated) gold nanoparticles (Au NPs) (12.4 ± 0.9 nm) to study the efflux kinetics of single BmrA membrane transporters of single live Bacillus subtillis cells, aiming to probe chemical dependent efflux functions of BmrA transporters and their potential chemical sensing capability. Similar to those observed using Ag NPs, accumulation of the intracellular Au NPs in single live cells (WT and ΔBmrA) highly depends upon the cellular expression of BmrA and the NP concentration (0.7 and 1.4 nM). The lower accumulation of intracellular Au NPs in WT (normal expression of BmrA) than ΔBmrA (deletion of bmrA) indicates that BmrA extrudes the Au NPs out of the WT cells. The accumulation of Au NPs in the cells increases with NP concentration, suggesting that the Au NPs most likely passively diffuse into the cells, similar to antibiotics. The result demonstrates that such small Au NPs can serve as imaging probes to study the efflux function of the BmrA membrane transporter in single live cells. Furthermore, the dependence of the accumulation rate of intracellular Au NPs in single live cells upon the expression of BmrA and the concentration of the NPs is about twice higher than that of the same sized Ag NPs. This interesting finding suggests the chemical-dependent efflux kinetics of BmrA and that BmrA could distinguish nearly identical sized Au NPs from Ag NPs and might possess chemical sensing machinery.

Single Nanoparticle Plasmonic Spectroscopy for Study of Charge-Dependent Efflux Function of Multidrug ABC Transporters of Single Live Bacillus subtilis Cells

Multidrug membrane transporters can selectively extrude a wide variety of structurally and functionally unrelated substrates, and they are responsible for ineffective treatment of a wide range of diseases (e.g., infection and cancer). Their underlying molecular mechanisms remain elusive. In this study, we functionalized Ag NPs (11 nm in diameter) with two biocompatible peptides (CALNNK, CALNNE) to prepare positively and negatively charged Ag-peptide NPs (Ag-CALNNK NPs+ζ, Ag-CALNNE NPs-4ζ), respectively. We used them as photostable plasmonic imaging probes to study charge-dependent efflux kinetics of BmrA (ABC) membrane transporter of single live Bacillus (B.) subtilis cells. Two strains of the cells, normal expression of BmrA (WT) or devoid of BmrA (ΔBmrA), were used to study the charge-dependent efflux kinetics of single NPs upon the expression of BmrA. The NPs (1.4 nM) were stable (non-aggregated) in a PBS buffer and biocompatible to the cells. We found the high dependent accumulation of the intracellular NPs in both WT and ΔBmrA upon the charge and concentration of NPs. Notably, the accumulation rates of the positively charged NPs in single live WT cells are nearly identical to those in ΔBmrA cells, showing independence upon the expression of BmrA. In contrast, the accumulation rates of the negatively charged NPs in WT are much lower than in ΔBmrA, showing high dependence upon the expression of BmrA and suggesting that BmrA extrude the negatively charged NPs, but not positively charged NPs, out of the WT. The accumulation of positively charged NPs in both WT and ΔBmrA increases nearly proportionally to the NP concentration. The accumulation of negatively charged NPs in ΔBmrA, but not in WT, also increases nearly proportionally to the NP concentration. These results suggest that both negatively and positively charged NPs enter the cells via passive diffusion driven by concentration gradients across the cellular membrane, and BmrA can only extrude the negatively charged NPs out of the WT. This study shows that single NP plasmon spectroscopy can serve as a powerful tool to identify single plasmonic NPs and to probe the charge-dependent efflux kinetics and function of single membrane transporters in single live cells in real time.

Single Nanoparticle Plasmonic Spectroscopy for Study of the Efflux Function of Multidrug ABC Membrane Transporters of Single Live Cells

ATP-binding cassette (ABC) membrane transporters exist in all living organisms and play key roles in a wide range of cellular and physiological functions. The ABC transporters can selectively extrude a wide variety of structurally and functionally unrelated substrates, leading to multidrug resistance. Despite extensive study, their efflux molecular mechanisms remain elusive. In this study, we synthesized and characterized purified silver nanoparticles (Ag NPs) (97 ± 13 nm in diameter), and used them as photostable optical imaging probes to study efflux kinetics of ABC membrane transporters (BmrA) of single live cells (B. subtillis). The NPs with concentrations up to 3.7 pM were stable (non-aggregated) in a PBS buffer and biocompatible with the cells. We found a high dependence of accumulation of the intracellular NPs in single live cells (WT, Ct-BmrA-EGFP, ΔbmrA) upon the cellular expression level of BmrA and NP concentration (0.93, 1.85 and 3.7 pM), showing the highest accumulation of intracellular NPs in ΔbmrA (deletion of BmrA) and the lowest ones in Ct-BmrA-EGFP (over-expression of BmrA). Interestingly, the accumulation of intracellular NPs in ΔbmrA increases nearly proportionally with the NP concentration, while those in WT and Ct-BrmA-EGFP do not. This suggests that the NPs enter the cells via passive diffusion driven by concentration gradients and are extruded out of cells by BmrA transporters, similar to conventional pump substrates (antibiotics). This study shows that such large substrates (84-100 nm NPs) can enter into the live cells and be extruded out of the cells by BmrA, and the NPs can serve as nm-sized optical imaging probes to study the size-dependent efflux kinetics of membrane transporters in single live cells in real time.

Real-time in vivo imaging of size-dependent transport and toxicity of gold nanoparticles in zebrafish embryos using single nanoparticle plasmonic spectroscopy

Noble metal nanoparticles (NPs) show distinctive plasmonic optical properties and superior photostability, enabling them to serve as photostable multi-coloured optical molecular probes and sensors for real-time in vivo imaging. To effectively study biological functions in vivo, it is essential that the NP probes are biocompatible and can be delivered into living organisms non-invasively. In this study, we have synthesized, purified and characterized stable (non-aggregated) gold (Au) NPs (86.2 ± 10.8 nm). We have developed dark-field single NP plasmonic microscopy and spectroscopy to study their transport into early developing zebrafish embryos (cleavage stage) and their effects on embryonic development in real-time at single NP resolution. We found that single Au NPs (75-97 nm) passively diffused into the embryos via their chorionic pore canals, and stayed inside the embryos throughout their entire development (120 h). The majority of embryos (96 ± 3%) that were chronically incubated with the Au NPs (0-20 pM) for 120 h developed to normal zebrafish, while an insignificant percentage of embryos developed to deformed zebrafish (1 ± 1)% or dead (3 ± 3)%. Interestingly, we did not observe dose-dependent effects of the Au NPs (0-20 pM) on embryonic development. By comparing with our previous studies of smaller Au NPs (11.6 ± 0.9 nm) and similar-sized Ag NPs (95.4 ± 16.0 nm), we found that the larger Au NPs are more biocompatible than the smaller Au NPs, while the similar-sized Ag NPs are much more toxic than Au NPs. This study offers in vivo assays and single NP microscopy and spectroscopy to characterize the biocompatibility and toxicity of single NPs, and new insights into the rational design of more biocompatible plasmonic NP imaging probes.

Silver nanoparticles induce developmental stage-specific embryonic phenotypes in zebrafish

Much is anticipated from the development and deployment of nanomaterials in biological organisms, but concerns remain regarding their biocompatibility and target specificity. Here we report our study of the transport, biocompatibility and toxicity of purified and stable silver nanoparticles (Ag NPs, 13.1 ± 2.5 nm in diameter) upon the specific developmental stages of zebrafish embryos using single NP plasmonic spectroscopy. We find that single Ag NPs passively diffuse into five different developmental stages of embryos (cleavage, early-gastrula, early-segmentation, late-segmentation, and hatching stages), showing stage-independent diffusion modes and diffusion coefficients. Notably, the Ag NPs induce distinctive stage and dose-dependent phenotypes and nanotoxicity, upon their acute exposure to the Ag NPs (0-0.7 nM) for only 2 h. The late-segmentation embryos are most sensitive to the NPs with the lowest critical concentration (CNP,c << 0.02 nM) and highest percentages of cardiac abnormalities, followed by early-segmentation embryos (CNP,c < 0.02 nM), suggesting that disruption of cell differentiation by the NPs causes the most toxic effects on embryonic development. The cleavage-stage embryos treated with the NPs develop into a wide variety of phenotypes (abnormal finfold, tail/spinal cord flexure, cardiac malformation/edema, yolk sac edema, and acephaly). These organ structures are not yet developed in cleavage-stage embryos, suggesting that the earliest determinative events to create these structures are ongoing, and disrupted by NPs, which leads to the downstream effects. In contrast, the hatching embryos are most resistant to the Ag NPs, and majority of embryos (94%) develop normally, and none of them develop abnormally. Interestingly, early-gastrula embryos are less sensitive to the NPs than cleavage and segmentation stage embryos, and do not develop abnormally. These important findings suggest that the Ag NPs are not simple poisons, and they can target specific pathways in development, and potentially enable target specific study and therapy for early embryonic development.

Silver nanoparticles incite size- and dose-dependent developmental phenotypes and nanotoxicity in zebrafish embryos

Nanomaterials possess distinctive physicochemical properties and promise a wide range of applications, from advanced technology to leading-edge medicine. However, their effects on living organisms remain largely unknown. Here we report that the purified silver nanoparticles (Ag NPs) (97 ± 13 nm) incite specific developmental stage embryonic phenotypes and nanotoxicity in a dose-dependent manner, upon acute exposure of given stage embryos to the NPs (0-24 pM) for only 2 h. The critical concentrations of the NPs that cause 50% of embryos to develop normally for cleavage, early gastrula, early segmentation, late segmentation, and hatching stage zebrafish embryos are 3.5, 4, 6, 6, and 8 pM, respectively, showing that the earlier developmental stage embryos are much more sensitive to the effects of the NPs than the later stage embryos. Interestingly, distinctive phenotypes (head abnormality and no eyes) are observed only in cleavage and early gastrula stage embryos treated with the NPs, showing the stage-specific effects of the NPs. By comparing these Ag NPs with smaller Ag NPs (13.1 ± 2.5 nm), we found that the embryonic phenotypes strikingly depend upon the sizes of Ag NPs and embryonic developmental stages. These notable findings suggest that the Ag NPs are unlike any conventional chemicals or ions. They can potentially enable target-specific study and therapy for early embryonic development in size-, stage-, dose-, and exposure duration-dependent manners.

Study of charge-dependent transport and toxicity of peptide-functionalized silver nanoparticles using zebrafish embryos and single nanoparticle plasmonic spectroscopy

Nanomaterials possess unusually high surface area-to-volume ratios and surface-determined physicochemical properties. It is essential to understand their surface-dependent toxicity in order to rationally design biocompatible nanomaterials for a wide variety of applications. In this study, we have functionalized the surfaces of silver nanoparticles (Ag NPs, 11.7 ± 2.7 nm in diameter) with three biocompatible peptides (CALNNK, CALNNS, CALNNE) to prepare positively (Ag-CALNNK NPs(+ζ)), negatively (Ag-CALNNS NPs(-2ζ)), and more negatively charged NPs (Ag-CALNNE NPs(-4ζ)), respectively. Each peptide differs in a single amino acid at its C-terminus, which minimizes the effects of peptide sequences and serves as a model molecule to create positive, neutral, and negative charges on the surface of the NPs at pH 4-10. We have studied their charge-dependent transport into early developing (cleavage-stage) zebrafish embryos and their effects on embryonic development using dark-field optical microscopy and spectroscopy (DFOMS). We found that all three Ag-peptide NPs passively diffused into the embryos via their chorionic pore canals, and stayed inside the embryos throughout their entire development (120 h), showing charge-independent diffusion modes and charge-dependent diffusion coefficients. Notably, the NPs create charge-dependent toxic effects on embryonic development, showing that the Ag-CALNNK NPs(+ζ) (positively charged) are the most biocompatible while the Ag-CALNNE NPs(-4ζ) (more negatively charged) are the most toxic. By comparing with our previous studies of the same sized citrated Ag and Au NPs, the Ag-peptide NPs are much more biocompatible than the citrated Ag NPs, and nearly as biocompatible as the Au NPs, showing the dependence of nanotoxicity upon the surface charges, surface functional groups, and chemical compositions of the NPs. This study also demonstrates powerful applications of single NP plasmonic spectroscopy for quantitative analysis of single NPs in vivo and in tissues, and reveals the possibility of rational design of biocompatible NPs.

Single nanoparticle spectroscopy for real-time in vivo quantitative analysis of transport and toxicity of single nanoparticles in single embryos

Nanomaterials exhibit distinctive physicochemical properties and promise a wide range of applications from nanotechnology to nanomedicine, which raise serious concerns about their potential environmental impacts on ecosystems. Unlike any conventional chemicals, nanomaterials are highly heterogeneous, and their properties can alter over time. These unique characteristics underscore the importance of study of their properties and effects on living organisms in real time at single nanoparticle (NP) resolution. Here we report the development of single-NP plasmonic microscopy and spectroscopy (dark-field optical microscopy and spectroscopy, DFOMS) and ultrasensitive in vivo assay (cleavage-stage zebrafish embryos, critical aquatic species) to study transport and toxicity of single silver nanoparticles (Ag NPs, 95.4 ± 16.0 nm) on embryonic developments. We synthesized and characterized purified and stable (non-aggregation) Ag NPs, determined their sizes and doses (number), and their transport mechanisms and effects on embryonic development in vivo in real time at single-NP resolution. We found that single Ag NPs passively entered the embryos through their chorionic pores via random Brownian diffusion and stayed inside the embryos throughout their entire development (120 h), suggesting that the embryos can bio-concentrate trace NPs from their environment. Our studies show that higher doses and larger sizes of Ag NPs cause higher toxic effects on embryonic development, demonstrating that the embryos can serve as ultrasensitive in vivo assays to screen biocompatibility and toxicity of the NPs and monitor their potential release into aquatic ecosystems.

Far-field photostable optical nanoscopy (PHOTON) for real-time super-resolution single-molecular imaging of signaling pathways of single live cells

Cellular signaling pathways play crucial roles in cellular functions and design of effective therapies. Unfortunately, study of cellular signaling pathways remains formidably challenging because sophisticated cascades are involved, and a few molecules are sufficient to trigger signaling responses of a single cell. Here we report the development of far-field photostable-optical-nanoscopy (PHOTON) with photostable single-molecule-nanoparticle-optical-biosensors (SMNOBS) for mapping dynamic cascades of apoptotic signaling pathways of single live cells in real-time at single-molecule (SM) and nanometer (nm) resolutions. We have quantitatively imaged single ligand molecules (tumor necrosis factor α, TNFα) and their binding kinetics with their receptors (TNFR1) on single live cells; tracked formation and internalization of their clusters and their initiation of intracellular signaling pathways in real-time; and studied apoptotic signaling dynamics and mechanisms of single live cells with sufficient temporal and spatial resolutions. This study provides new insights into complex real-time dynamic cascades and molecular mechanisms of apoptotic signaling pathways of single live cells. PHOTON provides superior imaging and sensing capabilities and SMNOBS offer unrivaled biocompatibility and photostability, which enable probing of signaling pathways of single live cells in real-time at SM and nm resolutions.

In vivo quantitative study of sized-dependent transport and toxicity of single silver nanoparticles using zebrafish embryos

Nanomaterials possess distinctive physicochemical properties (e.g., small sizes and high surface area-to-volume ratios) and promise a wide variety of applications, ranging from the design of high quality consumer products to effective disease diagnosis and therapy. These properties can lead to toxic effects, potentially hindering advances in nanotechnology. In this study, we have synthesized and characterized purified and stable (nonaggregation) silver nanoparticles (Ag NPs, 41.6 ± 9.1 nm in average diameter) and utilized early developing (cleavage-stage) zebrafish embryos (critical aquatic and eco- species) as in vivo model organisms to probe the diffusion and toxicity of Ag NPs. We found that single Ag NPs (30-72 nm diameters) passively diffused into the embryos through chorionic pores via random Brownian motion and stayed inside the embryos throughout their entire development (120 hours-post-fertilization, hpf). Dose- and size-dependent toxic effects of the NPs on embryonic development were observed, showing the possibility of tuning biocompatibility and toxicity of the NPs. At lower concentrations of the NPs (≤0.02 nM), 75-91% of embryos developed into normal zebrafish. At the higher concentrations of NPs (≥0.20 nM), 100% of embryos became dead. At the concentrations in between (0.02-0.2 nM), embryos developed into various deformed zebrafish. Number and sizes of individual Ag NPs embedded in tissues of normal and deformed zebrafish at 120 hpf were quantitatively analyzed, showing deformed zebrafish with higher number of larger NPs than normal zebrafish and size-dependent nanotoxicity. By comparing with our previous studies of smaller Ag NPs (11.6 ± 3.5 nm), we found striking size-dependent nanotoxicity that, at the same molar concentration, the larger Ag NPs (41.6 ± 9.1 nm) are more toxic than the smaller Ag NPs (11.6 ± 3.5 nm).

An outbreak of food-borne botulism in Scotland, United Kingdom, November 2011

An investigation is currently underway to explain an outbreak of food-borne botulism in Scotland. Three children in the same family were confirmed as having botulism following consumption of a meal made with a jar of korma sauce. Residual sauce from the jar, the jar lid and a remnant of the meal, all tested positive for Clostridium botulinum type A toxin. The children are recovering, although two remain ventilated and in intensive care unit.

Investigation of a Q fever outbreak in a Scottish co-located slaughterhouse and cutting plant

Outbreaks of Q fever are rare in the UK. In 2006, the largest outbreak of Q fever in Scotland occurred at a co-located slaughterhouse and cutting plant with 110 cases. Preliminary investigations pointed to the sheep lairage being the potential source of exposure to the infective agent. A retrospective cohort study was carried out among workers along with environmental sampling to guide public health interventions. A total of 179 individuals were interviewed of whom 66 (37%) were migrant workers. Seventy-five (41.9%) were serologically confirmed cases. Passing through a walkway situated next to the sheep lairage, a nearby stores area, and being male were independently associated with being serologically positive for Q fever. The large proportion of migrant workers infected presented a significant logistical problem during outbreak investigation and follow up. The topic of vaccination against Q fever for slaughterhouse workers is contentious out with Australasia, but this outbreak highlights important occupational health issues.

Probing of multidrug ABC membrane transporters of single living cells using single plasmonic nanoparticle optical probes

Currently, molecular mechanisms of multidrug ABC (ATP-binding cassette) membrane transporters remain elusive. In this study, we synthesized and characterized purified spherically shaped silver nanoparticles (Ag NPs) (11.8 +/- 2.6 nm in diameter), which were stable (non-aggregation) in PBS buffer and inside single living cells. We used the size-dependent localized surface plasmon resonance (LSPR) spectra of single Ag NPs to determine their sizes and to probe the size-dependent transport kinetics of the ABC (BmrA, BmrA-EGFP) transporters in single living cells (Bacillus subtilis) in real time at nanometer resolution using dark-field optical microscopy and spectroscopy (DFOMS). The results show that the smaller NPs stayed longer inside the cells than larger NPs, suggesting size-dependent efflux kinetics of the membrane transporter. Notably, accumulation and efflux kinetics of intracellular NPs for single living cells depended upon the cellular expression level of BmrA, NP concentrations, and a pump inhibitor (25 muM, orthovanadate), suggesting that NPs are substrates of BmrA transporters and that passive diffusion driven by concentration gradients is the primary mechanism by which the NPs enter the cells. The accumulation and efflux kinetics of intracellular NPs for given cells are similar to those observed using a substrate (Hoechst dye) of BmrA, demonstrating that NPs are suitable probes for study of multidrug membrane transporters of single living cells in real-time. Unlike fluorescent probes, single Ag NPs exibit size-dependent LSPR spectra and superior photostability, enabling them to probe the size-dependent efflux kinetics of membrane transporters of single living cells in real-time for better understanding of multidrug resistance.

Probing of multidrug ABC membrane transporters of single living cells using single plasmonic nanoparticle optical probes

Currently, molecular mechanisms of multidrug ABC (ATP-binding cassette) membrane transporters remain elusive. In this study, we synthesized and characterized purified spherically shaped silver nanoparticles (Ag NPs) (11.8 +/- 2.6 nm in diameter), which were stable (non-aggregation) in PBS buffer and inside single living cells. We used the size-dependent localized surface plasmon resonance (LSPR) spectra of single Ag NPs to determine their sizes and to probe the size-dependent transport kinetics of the ABC (BmrA, BmrA-EGFP) transporters in single living cells (Bacillus subtilis) in real time at nanometer resolution using dark-field optical microscopy and spectroscopy (DFOMS). The results show that the smaller NPs stayed longer inside the cells than larger NPs, suggesting size-dependent efflux kinetics of the membrane transporter. Notably, accumulation and efflux kinetics of intracellular NPs for single living cells depended upon the cellular expression level of BmrA, NP concentrations, and a pump inhibitor (25 muM, orthovanadate), suggesting that NPs are substrates of BmrA transporters and that passive diffusion driven by concentration gradients is the primary mechanism by which the NPs enter the cells. The accumulation and efflux kinetics of intracellular NPs for given cells are similar to those observed using a substrate (Hoechst dye) of BmrA, demonstrating that NPs are suitable probes for study of multidrug membrane transporters of single living cells in real-time. Unlike fluorescent probes, single Ag NPs exibit size-dependent LSPR spectra and superior photostability, enabling them to probe the size-dependent efflux kinetics of membrane transporters of single living cells in real-time for better understanding of multidrug resistance.

Electric pulses to prepare feeder cells for sustaining and culturing of undifferentiated embryonic stem cells

Current challenges in embryonic-stem cell (ESC) research include the inability of sustaining and culturing of undifferentiated ESCs over time. Growth-arrested feeder cells are essential to the culture and sustaining of undifferentiated ESCs, and they are currently prepared using gamma-radiation and chemical inactivation. Both techniques have severe limitations. In this study, we developed a new, simple and effective technique (pulsed electric fields, PEFs) to produce viable growth-arrested cells (RTS34st) and used them as high-quality feeder cells to culture and sustain undifferentiated zebrafish ESCs over time. The cells were exposed to 25 sequential 10-ns electric pulses (10nsEPs) of 25, 40 and 150 kV/cm with 1-s pulse interval, or 2 sequential 50-mus electric pulses (50microsEPs) of 2.83, 1.78 and 0.78 kV/cm with 5-s pulse interval, respectively. We found that the cellular effects of PEFs depended directly upon the duration, number and electric field strength of the pulses, showing the feasibility of tuning them to produce various types of growth-arrested cells for culturing undifferentiated ESCs. Both 10nsEPs of 40 kV/cm produced by a 10nsEP generator and 50microsEPs of 1.78 kV/cm provided by inexpensive and widely available conventional electroporators, generated high-quality growth-arrested feeder cells for proliferation of undifferentiated ESCs over time. PEFs can therefore be used to replace radiation and chemical inactivation methods for preparation of growth-arrested feeder cells for advancing ESC research.

An outbreak of infection with Bacillus anthracis in injecting drug users in Scotland

An investigation is currently underway to explore and control an outbreak of Bacillus anthracis among drug users (mainly injecting) in Scotland. Contaminated heroin or a contaminated cutting agent mixed with the heroin is considered to be the most likely source and vehicle of infection. Heroin users have been advised of the risk. The risk to the general public is regarded as very low.

Random walk of single gold nanoparticles in zebrafish embryos leading to stochastic toxic effects on embryonic developments

We have synthesized and characterized stable (non-aggregating, non-photobleaching and non-blinking), nearly monodisperse and highly-pure Au nanoparticles, and used them to probe nanoparticle transport and diffusion in cleavage-stage zebrafish embryos and to study their effects on embryonic development in real-time. We found that single Au nanoparticles (11.6 +/- 0.9 nm in diameter) passively diffused into the chorionic space of the embryos via their chorionic pore canals and continued their random-walk through chorionic space and into the inner mass of embryos. Diffusion coefficients of single nanoparticles vary dramatically (2.8 x 10(-11) to 1.3 x 10(-8) cm(2) s(-1)) as nanoparticles diffuse through the various parts of embryos, suggesting highly diverse transport barriers and viscosity gradients in the embryos. The amount of Au nanoparticles accumulated in embryos increases with nanoparticle concentration increases. Interestingly, however, their effects on embryonic development are not proportionally related to their concentration. The majority of embryos (74% on average) chronically incubated with 0.025-1.2 nM Au nanoparticles for 120 h developed to normal zebrafish, with some (24%) being dead and few (2%) deformed. We have developed a new approach to image and characterize individual Au nanoparticles embedded in tissues using histology sample preparation methods and localized surface plasmon resonance spectra of single nanoparticles. We found Au nanoparticles in various parts of normally developed and deformed zebrafish, suggesting that the random-walk of nanoparticles in embryos during their development might have led to stochastic effects on embryonic development. These results show that Au nanoparticles are much more biocompatible with (less toxic to) the embryos than the Ag nanoparticles that we reported previously, suggesting that they are better suited as biocompatible probes for imaging embryos in vivo. The results provide powerful evidences that the biocompatibility and toxicity of nanoparticles is highly dependent on their chemical properties, and that the embryos can serve as effective in vivo assays to screen their biocompatibility.

In vivo imaging of transport and biocompatibility of single silver nanoparticles in early development of zebrafish embryos

Real-time study of the transport and biocompatibility of nanomaterials in early embryonic development at single-nanoparticle resolution can offer new knowledge about the delivery and effects of nanomaterials in vivo and provide new insights into molecular transport mechanisms in developing embryos. In this study, we directly characterized the transport of single silver nanoparticles into an in vivo model system (zebrafish embryos) and investigated their effects on early embryonic development at single-nanoparticle resolution in real time. We designed highly purified and stable (not aggregated and no photodecomposition) nanoparticles and developed single-nanoparticle optics and in vivo assays to enable the study. We found that single Ag nanoparticles (5-46 nm) are transported into and out of embryos through chorion pore canals (CPCs) and exhibit Brownian diffusion (not active transport), with the diffusion coefficient inside the chorionic space (3 x 10(-9) cm(2)/s) approximately 26 times lower than that in egg water (7.7 x 10(-8) cm(2)/s). In contrast, nanoparticles were trapped inside CPCs and the inner mass of the embryos, showing restricted diffusion. Individual Ag nanoparticles were observed inside embryos at each developmental stage and in normally developed, deformed, and dead zebrafish, showing that the biocompatibility and toxicity of Ag nanoparticles and types of abnormalities observed in zebrafish are highly dependent on the dose of Ag nanoparticles, with a critical concentration of 0.19 nM. Rates of passive diffusion and accumulation of nanoparticles in embryos are likely responsible for the dose-dependent abnormalities. Unlike other chemicals, single nanoparticles can be directly imaged inside developing embryos at nanometer spatial resolution, offering new opportunities to unravel the related pathways that lead to the abnormalities.

The impact of long chain n-3 polyunsaturated fatty acid supplementation on inflammation, insulin sensitivity and CVD risk in a group of overweight women with an inflammatory phenotype

BACKGROUND

Inflammation is strongly related to obesity and the risk of cardiovascular disease (CVD). The metabolic benefits of long chain (LC) n-3 polyunsaturated fatty acid (PUFA) may be attributable to its anti-inflammatory properties.

OBJECTIVE

To investigate whether an individual's habitual inflammatory status influences the impact of a LC n-3 PUFA intervention on CVD risk.

DESIGN

The study was a randomized crossover design. Subjects received LC n-3 PUFA capsules or a placebo for 12 weeks, with 4-week washout between phases. Thirty women, in the top and bottom tertiles of baseline sialic acid concentration, formed raised inflammatory status (top, n = 12) and reference (bottom, n = 18) groups. Baseline data were analysed using one-way anova, differences between treatment phases were calculated at each timepoint and analysed using a random effects model.

RESULTS

At baseline, the raised inflammatory status group had significantly higher body mass index and area under the curve (AUC) insulin than the reference group. With LC n-3 PUFA supplementation, both groups showed significantly higher plasma eicosapentaenoic acid and docosahexaenoic acid at 4 and 12 weeks (p < 0.001), and lower triacylglycerols (4 weeks p < 0.01 and 12 weeks p < 0.05). The difference in AUC insulin between the two treatment phases at 12 weeks was significantly greater in the raised inflammatory status group compared to the reference group (p < 0.05). Inflammatory markers were significantly lower after 12 weeks LC n-3 PUFA supplementation compared to baseline (C-reactive protein p < 0.05 and interleukin-6 p < 0.01), but there was no significant group effect.

CONCLUSIONS

Habitual inflammatory status influences the impact of LC n-3 PUFA supplementation, but it is not clear whether the effect of LC n-3 PUFA on AUC insulin is mediated through inflammatory mechanisms.

Additive benefits of long-chain n-3 polyunsaturated fatty acids and weight-loss in the management of cardiovascular disease risk in overweight hyperinsulinaemic women

BACKGROUND

Obesity, inflammation, insulin resistance and cardiovascular disease (CVD) risk are inter-related. Both weight-loss and long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) are independently known to reduce metabolic risk, but the combined effects are unclear.

OBJECTIVE

This study examines whether addition of LC n-3 PUFA to a low fat/high carbohydrate weight-loss programme results in greater improvements in inflammation, insulin sensitivity and CVD risk, than weight-loss alone.

DESIGN

One hundred and sixteen overweight insulin-resistant women entered a 24-week randomised intervention study. Thirty-nine women were randomised to a weight-loss programme, with LC n-3 PUFA (WLFO), 38 to a weight-loss programme with placebo oil (WLPO), and 39 to receive placebo oil, with no weight-loss programme (control).

RESULTS

Ninety-three women completed the study (35 WLFO, 32 WLPO and 26 control), with significant weight-loss in WLFO (10.8+/-1.0%) and WLPO (12.4+/-1.0%) compared to the control group (P<0.0001). The WLFO, but not WLPO or control group, showed significant increases in adipose tissue LC n-3 PUFA (0.34+/-0.20 vs 0.17+/-0.10 and 0.16+/-0.10 %DHA, P<0.0001). Weight-loss showed significant improvements in insulin sensitivity (P<0.001), lipid profile (triglycerides P<0.05) and inflammation (sialic acid P<0.05). Time*group effects showed significant decreases in triglycerides (P<0.05) and increases in adiponectin (P<0.01) with LC n-3 PUFA, in the WLFO vs WLPO groups.

CONCLUSIONS

Weight-loss improved risk factors associated with CVD, with some additional benefits of LC n-3 PUFA on triglycerides and adiponectin. Given the current low dietary intake of LC n-3 PUFA, greater attention should be given to increase these fatty acids in the treatment of obesity.

Survey of zoonoses recorded in Scotland between 1993 and 2002

All the human and animal laboratory reports of zoonoses sent to Health Protection Scotland between 1993 and 2002 were identified. There were 24,946 reports from veterinary laboratories, and 94,718 (20 per cent) of the 468,214 reports from medical laboratories were considered to be zoonotic. The most common reports of zoonoses from people were Campylobacter, Salmonella, Cryptosporidium and Giardia species and Escherichia coli o157. The most common reports of zoonoses from animals were Salmonella, Cryptosporidium, Chlamydia and Campylobacter species and Mycobacterium avium paratuberculosis. For all the zoonoses in people, the National Health Service Board areas Borders, Dumfries and Galloway, Forth Valley, Grampian, Lanarkshire and Lothian had a higher than expected standardised incidence rate of infection, whereas Ayrshire and Arran, Fife, Greater Glasgow, Shetland, Tayside and Western Isles had a lower than expected rate. The organisms and diseases considered to be new and emerging were Rhodococcus species, Cyclospora cayetanensis, Leishmania species, Pneumocystis carinii (jiroveci) and bovine spongiform encephalopathy/variant Creutzfeldt-Jakob disease.

Discrimination ratio analysis of inflammatory markers: implications for the study of inflammation in chronic disease

To understand the role of inflammation in chronic disease it is important to have a reliable measure of habitual inflammatory status. A number of acute-phase response markers have been used as measures of inflammatory status, but the ability of a single measure to appropriately reflect habitual inflammatory status has not been assessed. This study compares the ability of different inflammatory markers to characterize habitual inflammatory status in overweight women. A single fasting blood sample was taken from 86 overweight women (mean body mass index [BMI], 35.2 kg/m2; range, 26.2 to 47.6 kg/m2) and a number of inflammatory markers (both acute-phase response markers and cytokines) were measured. A randomly selected subpopulation of 15 women attended on 2 further occasions for further blood samples. Using the subpopulation, discrimination ratios (DRs) were calculated for each inflammatory marker to assess the within-subject variability. The DRs were then used to determine the relationship between these markers, adjusted for within-subject variability, in the whole population. In this highly controlled experimental environment, interleukin-6 (IL-6), with a DR of 3.71, was the cytokine with the greatest ability to discriminate between subjects, suggesting that it is best able to characterize habitual inflammatory status. Sialic acid was the acute-phase response marker with the highest DR (3.16), and showed stronger correlations with other inflammatory markers, including C-reactive protein (CRP), than IL-6. This study suggests that use of some inflammatory markers, such as CRP, with large within-individual variability, will underestimate the relationship between inflammation and disease, and thus relationships between inflammation and chronic disease may be stronger than previously appreciated. Future studies should consider IL-6 or sialic acid to provide a more robust measure of inflammatory status.

Elevated sialic acid, but not CRP, predicts features of the metabolic syndrome independently of BMI in women

AIMS

C-reactive protein (CRP) is a predictor of many diseases including type II diabetes and cardiovascular disease. Fewer studies have similarly shown sialic acid (SA) to be a predictor of obesity-related diseases, but importantly SA shows less intra-individual variability than CRP and acts as an integrated marker of the activity of a number of acute-phase proteins. This study examines the association between both CRP and SA with individual and combined features of the metabolic syndrome.

SUBJECTS

In all, 257 women with a body mass index (BMI) ranging from 25.1 to 54.5 kg/m2 (geometric mean 33.1+/-5.8 kg/m2) and aged 19-71 y (mean 45.6+/-12.1 y) were studied. Subjects had no symptoms of intercurrent infection, known diabetes, treated dyslipidaemia, a chronic inflammatory condition, liver disease or malignancy.

RESULTS

Linear regression demonstrates that both CRP and SA were positively associated with weight, BMI, insulin resistance, dyslipidaemia and hypertension. There was a highly significant (P<0.0001) positive association of both SA and CRP with none, one, two, three or four features of the metabolic syndrome. For a 1 s.d. (4.0 mg/l) increase in CRP, there was a significant increased risk when comparing the odds of having metabolic syndrome (defined as three or more individual features) compared with the remainder of the population (odds ratio=1.7, P<0.0001), but this was not significant after adjustment for BMI. However, for a 1 s.d. (0.34 mmol/l) increase in SA, the odds of having metabolic syndrome compared with those without metabolic syndrome was 2.5 (P<0.0001), and persisted after additional adjustment for BMI (adjusted odds ratio=1.9, P<0.0001).

CONCLUSIONS

While SA and CRP are both univariately associated with individual features of the metabolic syndrome, SA, but not CRP, is significantly associated with the metabolic syndrome, independent of BMI. We conclude that SA identifies a subgroup of overweight individuals with an inflammatory phenotype, who are at the greatest risk of metabolic syndrome.

Investigation of human infections with Salmonella enterica serovar Java in Scotland and possible association with imported poultry

PFGE analysis of S. Java strains (29 from humans, 30 from poultry meat) showed two major clusters. All isolates from poultry imported from the Netherlands belonged to Cluster A, which also comprised 10 human isolates. Thirty-one of the 37 isolates in this cluster had an identical JavX1 pattern, similar to the X8 profile of a particular S. Java clone predominant in poultry production in several European countries. Cluster B comprised 19 human isolates and two poultry isolates of unknown origin. These results combined with epidemiological data and information on the origins of poultry meat strongly suggested that imported poultry meat is an important source of Java infections in humans in Scotland.

Risk factors for sporadic cases of Escherichia coli O157 infection: the importance of contact with animal excreta

To determine environmental risk factors for sporadic E. coli O157 infection in Scotland we undertook a prospective, matched case-control study between 1 October 1996 and 31 March 1999. One hundred and eighty-three cases and 545 matched controls were recruited. Contact with animal faeces (OR = 3.65; 95% CI 1.81, 7.34: P < 0.0005) and likely contact with animal faeces (OR = 4.8; 95% CI 2.42, 9.48; P < 0.0005) emerged as strong risk factors for infection. Certain exposures (mainly food-related) were inversely associated with infection i.e. were statistically protective. Most striking was the consumption of bottled water (OR = 0.28; 95% CI 0.15, 0.52; P < 0.0005). Transmission of E. coli O157 does not occur simply through contaminated food. Members of the public need to be aware of the potential for acquiring E. coli O157 through contamination of the environment with animal faeces so that they may take measures to mitigate their risk.

Molecular analysis of Salmonella enterica serotype Dublin: building bridges between population genetic and molecular epidemiological studies

Population genetic studies of Salmonella enterica serotype Dublin using multilocus enzyme electrophoresis have recognised two dominant clones termed Du1 and Du3. The characterisation of plasmids in Dublin suggests greater strain diversity. The application of restriction enzyme fragmentation pattern (REFP) analysis of genomic DNA using Sau3A and HincII together with plasmid subtractive analysis can resolve anomalies in earlier comparisons. Twenty-six isolates were selected for inclusion in the study. All had been previously characterised with respect to their plasmids, and were isolated from the USA, Canada and five European countries. On the basis of plasmid profiles, 17 were predicted to correspond with Du1 and Du3. Sau3A digestion generated two distinct REFPs (A and B) of < 70% similarity, which corresponded with Du1 and Du3. After the contribution of plasmid-derived bands was subtracted, two variants of A (A1 and A2) and four of B (B1, B2, B3 and B4) were recognised. Seventeen were concordant with predictions from population genetic studies. Nine that could not be predicted on the basis of atypical plasmid profiles all showed REFP A1 (Du1) and were consistent with the incursion of additional plasmids or plasmid cointegration. REFPs from HincII digests generally corroborated Sau3A data but showed greater overall similarity between the strains and more influence from plasmid DNA.

Diversity and molecular variation among plasmids in Salmonella enterica serotype Dublin based on restriction enzyme fragmentation pattern analysis

Molecular variation within and between plasmids of Salmonella enterica serotype Dublin was analysed. Such variation has been demonstrated in the serotype-specific plasmids (SSP's) of Typhimurium and Enteritidis. The two aims of this study were to determine the plasmid diversity in a host-adapted serotype and also the incidence of molecular variation in the SSP among strains of Dublin using restriction endonuclease fragmentation pattern (REFP) analysis with Pst1, Sma1 and EcoRV. Sixty-five strains were examined from seven countries. Plasmid profile and REFP analysis showed that none of the strains was plasmid-free. Seventy-seven percent of the strains possessed the 72 kb SSP either alone or in combination with another plasmid; 23% harboured plasmids which were molecular variants of the SSP. Four of the variants were more closely related to each other than to the reference SSP and were harboured by Dublin isolated from both the USA and Europe. A further three were shown to be cointegrate plasmids and were similarly distributed. Thirty-two percent of strains possessed the SSP alone. None of the UK strains was resistant to any of the antimicrobial agents tested whereas 74% of the remaining strains were resistant to between one and five antimicrobial agents. This study corroborates previous findings concerning the high degree of stability of the SSP and confirmed the clonal nature of Dublin. Co-resident plasmids provided evidence of sub-clones within localized geographical areas.