Role of group A streptococcal IgG-binding proteins in triggering experimental glomerulonephritis in the rabbit

Our previous studies have indicated that the IgG-binding M-family proteins (IgGBP) of group A streptococci may be involved in eliciting experimental acute poststreptococcal glomerulonephritis (APSGN) in the rabbit. These surface proteins were also found to trigger production of anti-IgG, which might conceivably act to enhance renal deposition of immune complexes (IC). In the present study, a clinical isolate of serotype M22 (strain AL168), an isogenic double mutant deficient for both the IgGBPs Mrp and Emm, as well as mutants deficient in only one of the proteins were tested for capacity to induce glomerulonephritis. Streptococci to be used for injecting rabbits were heat-killed. Surface-bound IgG was removed by 1 M KSCN and cells were then repeatedly washed in PBS before use. Rabbits were injected intravenously with 109 cells three times a week for 8 weeks and, following one month of rest, for another 6 weeks. Deposits of IgG and C3 as well as induced chemokines TNF-alpha, IL-1beta and IL-6 were traced in cryostat sections using specific antibodies and appropriate peroxidase-labelled anti-antibodies. In four rabbits immunized with the double mutant strain, no deposits were found, and as examined by TEM, only subtle and transient renal changes were observed. In contrast, the original strain AL168 induced pronounced inflammatory and degenerative glomerular changes in all four rabbits injected, and deposits of TNF-alpha, IL-1beta and IL-6 were found in mesangial and endothelial cells. Similar deposits and glomerular changes were seen in all eight rabbits injected with the mrp-emm+ mutant and in four out of seven animals receiving the mrp+emm- mutant. There was a highly significant correlation between high levels of circulating anti-IgG and development of APSGN. These results confirm an important role of streptococcal IgGBP in triggering experimental APSGN as earlier proposed by our group.     

Basismaßnahmen zur Wiederbelebung Erwachsener (Basic Life Support)

Notfall + Rettungsmedizin - Der Europäische Rat für Wiederbelebung hat diese Leitlinie – Basismaßnahmen zur Wiederbelebung – auf Grundlage des...     

Reconstruction of an active SOCS3-based E3 ubiquitin ligase complex in vitro: identification of the active components and JAK2 and gp130 as substrates

Abstract

SOCS3 (suppressor of cytokine signaling 3) inhibits the intracellular signaling cascade initiated by exposure of cells to cytokines. SOCS3 regulates signaling via two distinct mechanisms: directly inhibiting the catalytic activity of Janus kinases (JAKs) that initiate the intracellular signaling cascade and catalysing the ubiquitination of signaling components by recruiting components of an E3 ubiquitin ligase complex. Here we investigate the latter mode-of-action biochemically by reconstructing a SOCS3-based E3 ubiquitin ligase complex in vitro using fully purified, recombinant components and examining its ability to promote the ubiquitination of molecules involved in the cytokine signaling cascade. We show that SOCS3 is an active substrate recruitment module for a Cullin5-based E3 ligase and have defined the core protein components required for ubiquitination. SOCS3-induced polyubiquitination was rapid and could proceed through a number of different ubiquitin lysines. SOCS3 catalyzed the ubiquitination of both the IL-6 receptor common chain (gp130) and JAK2.     

Detecting accidental punctures and lacerations during cholecystectomy in large datasets: Two methods of analysis

Background: After the Institute of Medicine(IOM) report To Err Is Human highlighted the impact of medical errors, the Agency for Healthcare Research and Quality(AHRQ) developed Patient-Safety Indicators(PSI) to improve quality by identifying potential inpatient safety problems. PSI-15 was created to study accidental punctures and lacerations(APL), but PSI-15 may underestimate APLs in populations of patients. This study compares PSI-15 with a more inclusive approach using a novel composite of secondary diagnostic and procedural codes. Methods: We used Nationwide Inpatient Sample(NIS) data(20 0 0–2012) from AHRQ's Healthcare Cost and Utilization Project(H-CUP). We analyzed PSI-15-positive and-negative cholecystectomies. Cross tabulations identified codes that were significantly more frequent among PSI-15-positive cases; these secondary diagnostic and procedural codes were selected as candidate members of a composite marker(CM) of APL. We chose cholecystectomy patients for study because this is one of the most common general operations, and the large size of NIS allows for meaningful analysis of infrequent occurrences such as APL rates. Results: CM identified 1.13 times more APLs than did PSI-15. Patients with CM-detected APLs were significantly older and had worse mortality, comorbidities, lengths of stay, and charges than those detected with PSI-15. Further comparison of these two approaches revealed that time-series analysis for both APL markers revealed parallel trends, with inflections in 2007, and lowest APL rates in July. Conclusions: Although CM may yield more false positives, it appears more inclusive, identifying more clinically significant APLs, than PSI-15. Both measures presented similar trends over time, arguing against inflation in PSI-15 reporting. While arguably less specific, CM may increase sensitivity for detecting APL events during cholecystectomies. These results may inform the interpretation of other large population studies of APLs following abdominal operations.     

Ten most notable family medicine research studies in Canada

Objective

To identify 10 noteworthy Canadian family medicine research studies that have affected practice in order to demonstrate the unique value that Canadian family medicine research offers.

Composition of the committee

Representatives from the Section of Researchers (SOR) and the Health Policy and Government Relations department of the College of Family Physicians of Canada developed a framework for inclusion and identified an initial list of articles. Members of the SOR Council and research directors from the 17 Canadian departments of family medicine reviewed the preliminary list and suggested additional studies.

Methods

The authors developed an initial list of studies carried out by Canadian family medicine researchers from those researchers who had received awards from the College of Family Physicians of Canada since 2002. Additional studies were proposed by members of the SOR Council and the university research directors. A total of 36 published articles were reviewed by the SOR authors, and an annotated short list of 16 articles was prepared. From that list, the other authors identified 7 noteworthy studies that were used to form the basis of advocacy materials. The SOR authors, along with 3 additional members of the SOR Executive, used an informal consensus process to select the final 3 articles to arrive at the top 10.

Report

The top 10 most noteworthy family medicine research studies are presented in this article and represent the unique contribution that Canadian family medicine research brings to health care in Canada. They have helped advance health care quality and improve care delivery, beneficially influencing health care practices, health care policy, and patient experiences.

Conclusion

This project has identified 10 classic Canadian family medicine research studies that continue to influence practice today. In addition to their usefulness as tools for teaching, advocating, and championing the contribution of research to modern family practice, these studies are important examples of the value of research to patient health in Canada and around the world.     

Bacterial Heterogeneity Is a Requirement for Host Superinfection by the Lyme Disease Spirochete

In nature, mixed Borrelia burgdorferi infections are common and possibly can be acquired by either superinfection or coinfection. Superinfection by heterologous B. burgdorferi strains has been established experimentally, although the ability of homologous B. burgdorferi clones to superinfect a host has not been studied in detail. Information regarding any potential immune barriers to secondary infection also currently is unavailable. In the present study, the ability to superinfect various mouse models by homologous wild-type clones was examined and compared to superinfection by heterologous strains. To assess the ability of homologous B. burgdorferi clones to successfully superinfect a mouse host, primary- and secondary-infecting spirochetes were recovered via in vitro cultivation of collected blood or tissue samples. This was accomplished by generating two different antibiotic-resistant versions of the wild-type B31-A3 clone in order to distinguish superinfecting B. burgdorferi from primary-infecting spirochetes. The data demonstrate an inability of homologous B. burgdorferi to superinfect immunocompetent mice as opposed to heterologous strains. Attempts to superinfect different types of immunodeficient mice with homologous B. burgdorferi indicate that the murine innate immune system represents a major barrier to intrastrain superinfection. Consequently, the possibility of innate immunity as a driving force for B. burgdorferi heterogeneity during the enzootic cycle is discussed.     

Free-standing Li+-conductive films based on PEO–PVDF blends

Solid electrolytes are of high interest for the development of advanced electrochemical energy storage devices with all-solid-state architectures. Here, we report the fabrication of the electrolyte membranes based on LiTFSI (LiN(CF₃SO₂)₂) and PEO–PVDF blends with improved properties. We show that addition of PVDF enables preparation of free-standing films of the compositions within the so called “crystallinity gap” of the LiTFSI–PEO system known to provide high ion conductivity. We show that optimal PVDF content enables preparation of the films with reasonable elastic modulus and high ionic conductivity of about 0.3 mS cm⁻¹ at 60 °C and about 0.1 mS cm⁻¹ at room-temperature. Combining FTIR spectroscopy, XRD and DSC measurements we show that a noticeable fraction of PVDF remains crystalline and enhances the mechanical properties of the material, and at the same time it additionally promotes LiTFSI dissociation and disordering. Density functional theory calculations showed that the Li⁺–PEO–PVDF complexation energy magnitude is almost as high as that of Li–PEO complexes, thus the salt dissociation ability can be retained in spite of the introduction of the substantial amounts of PVDF required for mechanical stability.

Addition of PVDF to LiTFSI–PEO solid electrolytes enables preparation of free-standing films with the compositions within the so called “crystallinity gap” of LiTFSI–PEO system. Such films possess ionic conductivity of about 0.3 mS cm⁻¹ at 60 °C.     

Study of the Hydrolytic Stability of Fine-Grained Ceramics Based on Y2.5Nd0.5Al5O12 Oxide with a Garnet Structure under Hydrothermal Conditions

The hydrolytic stability of ceramics based on Y_2.5Nd_0.5Al₅O₁₂ oxide with a garnet structure obtained by the spark plasma sintering (SPS) method has been studied. The tests were carried out in distilled water under hydrothermal conditions in an autoclave and, for comparison, in a static mode at room temperature. The mechanism of leaching of Y and Nd from the ceramics was investigated. It has been shown that at “low” temperatures (25 and 100 °C), the destruction of pores occured, and the intensity of the leaching process was limited by the diffusion of ions from the inner part of the sample to the surface. At “high” test temperatures (200 and 300 °C), intense destruction of the ceramic grain boundaries was observed. It was assumed that the accelerated leaching of neodymium is due to the formation of grain-boundary segregations of Nd³⁺ in sintered ceramics.