Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that has reemerged to cause profound epidemics of fever, rash, and arthralgia throughout sub-Saharan Africa, Southeast Asia, and the ...Caribbean. Like other arthritogenic alphaviruses, mechanisms of CHIKV pathogenesis are not well defined. Using the attenuated CHIKV strain 181/25 and virulent strain AF15561, we identified a residue in the E2 viral attachment protein that is a critical determinant of viral replication in cultured cells and pathogenesis in vivo. Viruses containing an arginine at E2 residue 82 displayed enhanced infectivity in mammalian cells but reduced infectivity in mosquito cells and diminished virulence in a mouse model of CHIKV disease. Mice inoculated with virus containing an arginine at this position exhibited reduced swelling at the site of inoculation with a concomitant decrease in the severity of necrosis in joint-associated tissues. Viruses containing a glycine at E2 residue 82 produced higher titers in the spleen and serum at early times postinfection. Using wild-type and glycosaminoglycan (GAG)-deficient Chinese hamster ovary (CHO) cell lines and soluble GAGs, we found that an arginine at residue 82 conferred greater dependence on GAGs for infection of mammalian cells. These data suggest that CHIKV E2 interactions with GAGs diminish dissemination to lymphoid tissue, establishment of viremia, and activation of inflammatory responses early in infection. Collectively, these results suggest a function for GAG utilization in regulating CHIKV tropism and host responses that contribute to arthritis.
CHIKV is a reemerging alphavirus of global significance with high potential to spread into new, immunologically naive populations. The severity of CHIKV disease, particularly its propensity for chronic musculoskeletal manifestations, emphasizes the need for identification of genetic determinants that dictate CHIKV virulence in the host. To better understand mechanisms of CHIKV pathogenesis, we probed the function of an amino acid polymorphism in the E2 viral attachment protein using a mouse model of CHIKV musculoskeletal disease. In addition to influencing glycosaminoglycan utilization, we identified roles for this polymorphism in differential infection of mammalian and mosquito cells and targeting of CHIKV to specific tissues within infected mice. These studies demonstrate a correlation between CHIKV tissue tropism and virus-induced pathology modulated by a single polymorphism in E2, which in turn illuminates potential targets for vaccine and antiviral drug development.
Worldwide, there are more than 10 million new cancer cases each year, and cancer is the cause of approximately 12% of all deaths. Given this, a large number of epidemiologic studies have been ...undertaken to identify potential risk factors for cancer, amongst which the association with trace elements has received considerable attention. Trace elements, such as selenium, zinc, arsenic, cadmium, and nickel, are found naturally in the environment, and human exposure derives from a variety of sources, including air, drinking water, and food. Trace elements are of particular interest given that the levels of exposure to them are potentially modifiable. In this review, we focus largely on the association between each of the trace elements noted above and risk of cancers of the lung, breast, colorectum, prostate, urinary bladder, and stomach. Overall, the evidence currently available appears to support an inverse association between selenium exposure and prostate cancer risk, and possibly also a reduction in risk with respect to lung cancer, although additional prospective studies are needed. There is also limited evidence for an inverse association between zinc and breast cancer, and again, prospective studies are needed to confirm this. Most studies have reported no association between selenium and risk of breast, colorectal, and stomach cancer, and between zinc and prostate cancer risk. There is compelling evidence in support of positive associations between arsenic and risk of both lung and bladder cancers, and between cadmium and lung cancer risk.
Sepsis describes the life-threatening systemic inflammatory response (SIRS) of an organism to an infection and is the leading cause of mortality on intensive care units (ICU) worldwide. An acute ...episode of sepsis is characterized by the extensive release of cytokines and other mediators resulting in a dysregulated immune response leading to organ damage and/or death. This initial pro-inflammatory burst often transits into a state of immune suppression characterised by loss of immune cells and T-cell dysfunction at later disease stages in sepsis survivors. However, despite these appreciations, the precise nature of the evoked defect in T-cell immunity in post-acute phases of SIRS remains unknown. Here we present an in-depth functional analysis of T-cell function in post-acute SIRS/sepsis. We document that T-cell function is not compromised on a per cell basis in experimental rodent models of infection-free SIRS (LPS or CpG) or septic peritonitis. Transgenic antigen-specific T-cells feature an unaltered cytokine response if challenged in vivo and ex vivo with cognate antigens. Isolated CD4(+)/CD8(+) T-cells from post-acute septic animals do not exhibit defects in T-cell receptor-mediated activation at the the level of receptor-proximal signalling, activation marker upregulation or expansion. However, SIRS/sepsis induced transient lymphopenia and gave rise to an environment of immune attenuation at post acute disease stages. Thus, systemic inflammation has an acute impact on T-cell numbers and adaptive immunity, but does not cause major cell-autonomous enduring functional defects in T-cells.
In the Gulf of Alaska (GOA), mesoscale eddies play an important role in promoting off-shelf transport of heat, nutrients and biological populations into the HNLC water of the northeast Pacific Ocean. ...However, the spatial and temporal distribution of these eddies and their characteristics have not been substantially described. Here we apply an objective method (Okubo–Weiss parameter) for identifying and tracking eddies to 15 years (October 1992–2006) of satellite sea level anomaly data. The parameter allows the spatial and temporal variability in eddy activity to be defined, providing the first systematic census of anticyclonic eddies in the region. Eddies are generated principally on the eastern side of the basin and propagate either westward (Haida eddies) or along the western GOA shelf break (Alaskan Stream eddies). Seasonal maps of eddy density show fewest eddies in winter, maximum in spring/summer. The Haida and Alaskan Stream eddy corridors are clearly defined, as is an ‘eddy desert’ in the southwest of the basin, where the probability of an eddy being identified is zero. Maps of eddy trajectories for each year show substantial interannual variability in number and propagation paths. Greatest eddy activity occurs in 1994, 1997/1998 and 2004. Fewest eddies occur in 1996 and in the period from 1999 through 2002. Interannual variability in eddy characteristics (magnitude, propagation speed, diameter and duration) is assessed for the basin as a whole, and separately for the Alaskan Stream, Haida and Sitka/Yakutat formation regions. In general, Alaskan Stream eddies are more numerous, larger and more intense than Haida eddies. Periods of increased eddy activity do not necessarily correspond to El Niño events, but are associated with anomalous downwelling wind conditions along the continental margin.
Mismatch repair (MMR) of replication errors requires DNA ends that can direct repair to the newly synthesized strand containing the error. For all but those organisms that use adenine methylation to ...generate nicks, the source of these ends in vivo is unknown. One possibility is that MMR may have a "special relation to the replication complex" Wagner R, Jr., Meselson M (1976) Proc Natl Acad Sci USA 73:4135-4139, perhaps one that allows 5' or 3' DNA ends associated with replication to act as strand discrimination signals. Here we examine this hypothesis, based on the logic that errors made by yeast DNA polymerase α (Pol α), which initiates Okazaki fragments during lagging-strand replication, will always be closer to a 5' end than will be more internal errors generated by DNA polymerase δ (Pol δ), which takes over for Pol α to complete lagging-strand replication. When we compared MMR efficiency for errors made by variant forms of these two polymerases, Msh2-dependent repair efficiencies for mismatches made by Pol α were consistently higher than for those same mismatches when made by Pol δ. Thus, one special relationship between MMR and replication is that MMR is more efficient for the least accurate of the major replicative polymerases, exonuclease-deficient Pol α. This observation is consistent with the close proximity and possible use of 5' ends of Okazaki fragments for strand discrimination, which could increase the probability of Msh2-dependent MMR by 5' excision, by a Msh2-dependent strand displacement mechanism, or both.
The ideal clinical diagnostic system should deliver rapid, sensitive, specific and reproducible results while minimizing the requirements for specialized laboratory facilities and skilled ...technicians. We describe an integrated diagnostic platform, the "FilmArray", which fully automates the detection and identification of multiple organisms from a single sample in about one hour. An unprocessed biologic/clinical sample is subjected to nucleic acid purification, reverse transcription, a high-order nested multiplex polymerase chain reaction and amplicon melt curve analysis. Biochemical reactions are enclosed in a disposable pouch, minimizing the PCR contamination risk. FilmArray has the potential to detect greater than 100 different nucleic acid targets at one time. These features make the system well-suited for molecular detection of infectious agents. Validation of the FilmArray technology was achieved through development of a panel of assays capable of identifying 21 common viral and bacterial respiratory pathogens. Initial testing of the system using both cultured organisms and clinical nasal aspirates obtained from children demonstrated an analytical and clinical sensitivity and specificity comparable to existing diagnostic platforms. We demonstrate that automated identification of pathogens from their corresponding target amplicon(s) can be accomplished by analysis of the DNA melting curve of the amplicon.
Tuberculosis vaccine development is hindered by the lack of validated immune correlates of protection. Exploring immune correlates of risk of disease and/or infection in prospective samples can ...inform this field. We investigate whether previously identified immune correlates of risk of TB disease also associate with increased risk of M.tb infection in BCG-vaccinated South African infants, who became infected with M.tb during 2-3 years of follow-up. M.tb infection is defined by conversion to positive reactivity in the QuantiFERON test. We demonstrate that inflammation and immune activation are associated with risk of M.tb infection. Ag85A-specific IgG is elevated in infants that were subsequently infected with M.tb, and this is coupled with upregulated gene expression of immunoglobulin-associated genes and type-I interferon. Plasma levels of IFN-Formula: see text2, TNF-Formula: see text, CXCL10 (IP-10) and complement C2 are also higher in infants that were subsequently infected with M.tb.
Monocytes are crucial immune cells involved in regulation of inflammation either directly or via differentiation into macrophages in tissues. However, many aspects of how their function is controlled ...in health and disease are not understood. Here we show that human blood monocytes activate high levels of the cytokine TGFβ, a pathway that is not evident in mouse monocytes. Human CD14
, but not CD16
, monocytes activate TGFβ via expression of the integrin αvβ8 and matrix metalloproteinase 14, which dampens their production of TNFα in response to LPS. Additionally, when monocytes differentiate into macrophages, integrin expression and TGFβ-activating ability are maintained in anti-inflammatory macrophages but down-regulated in pro-inflammatory macrophages. In the healthy human intestine, integrin αvβ8 is highly expressed on mature tissue macrophages, with these cells and their integrin expression being significantly reduced in active inflammatory bowel disease. Thus, our data suggest that integrin αvβ8-mediated TGFβ activation plays a key role in regulation of monocyte inflammatory responses and intestinal macrophage homeostasis.
Objectives The aim of this study was to evaluate whether chronic heart failure (HF) therapy guided by concentrations of amino-terminal pro–B-type natriuretic peptide (NT-proBNP) is superior to ...standard of care (SOC) management. Background It is unclear whether standard HF treatment plus a goal of reducing NT-proBNP concentrations improves outcomes compared with standard management alone. Methods In a prospective single-center trial, 151 subjects with HF due to left ventricular (LV) systolic dysfunction were randomized to receive either standard HF care plus a goal to reduce NT-proBNP concentrations ≤1,000 pg/ml or SOC management. The primary endpoint was total cardiovascular events between groups compared using generalized estimating equations. Secondary endpoints included effects of NT-proBNP–guided care on patient quality of life as well as cardiac structure and function, assessed with echocardiography. Results Through a mean follow-up period of 10 ± 3 months, a significant reduction in the primary endpoint of total cardiovascular events was seen in the NT-proBNP arm compared with SOC (58 events vs. 100 events, p = 0.009; logistic odds for events 0.44, p = 0.02); Kaplan-Meier curves demonstrated significant differences in time to first event, favoring NT-proBNP–guided care (p = 0.03). No age interaction was found, with elderly patients benefitting similarly from NT-proBNP–guided care as younger subjects. Compared with SOC, NT-proBNP–guided patients had greater improvements in quality of life, demonstrated greater relative improvements in LV ejection fraction, and had more significant improvements in both LV end-systolic and -diastolic volume indexes. Conclusions In patients with HF due to LV systolic dysfunction, NT-proBNP–guided therapy was superior to SOC, with reduced event rates, improved quality of life, and favorable effects on cardiac remodeling. (Use of NT-proBNP Testing to Guide Heart Failure Therapy in the Outpatient Setting; NCT00351390 )
Treating messenger RNA transcript abundances as quantitative traits and mapping gene expression quantitative trait loci for these traits has been pursued in gene-specific ways. Transcript abundances ...often serve as a surrogate for classical quantitative traits in that the levels of expression are significantly correlated with the classical traits across members of a segregating population. The correlation structure between transcript abundances and classical traits has been used to identify susceptibility loci for complex diseases such as diabetes and allergic asthma. One study recently completed the first comprehensive dissection of transcriptional regulation in budding yeast, giving a detailed glimpse of a genome-wide survey of the genetics of gene expression. Unlike classical quantitative traits, which often represent gross clinical measurements that may be far removed from the biological processes giving rise to them, the genetic linkages associated with transcript abundance affords a closer look at cellular biochemical processes. Here we describe comprehensive genetic screens of mouse, plant and human transcriptomes by considering gene expression values as quantitative traits. We identify a gene expression pattern strongly associated with obesity in a murine cross, and observe two distinct obesity subtypes. Furthermore, we find that these obesity subtypes are under the control of different loci.
PDF
