An idiotypic cross-reaction between allotype a3 and allotype a negative rabbit antibodies to streptococcal carbohydrates

Two antibodies to Group C streptococcal carbohydrate isolated from an individual rabbit had similar relative binding affinities for a Group C immuno-adsorbent column. Their light chains were similar, if not identical, as were the constant regions of their heavy chains. Differences in the variable regions of the H chains of the two antibodies were detected by chemical analysis. The two antibodies had serologically identical idiotypic determinants although one antibody possessed the a3 allotype and the other had no detectable group a marker. The occurrence of such antibodies indicates the absence of obligatory associations between group a allotypes and idiotypic specificities, despite the fact that both determinants have antigenic components in the VH region of the H chain

A Holistic Social Constructionist perspective to Enterprise Education

Purpose – Drawing on the Gestalt approach this article proposes a holistic framework for enterprise education (EE) research based on Social Constructionism, illustrating how the latter supports research into experiential learning in EE in 7 UK Higher Education (HE) pharmacy schools. Design/ Methodology/ Approach – This paper is based on a qualitative empirical study involving educators in UK Higher Education Institution (HEI) pharmacy schools in semi-structured interviews, and investigates the delivery of EE through experiential learning approaches. Social Constructionism is proposed as a suitable underlying philosophical paradigm. Findings – A Social Constructionism paradigm, which adopts relative realism ontology, transactional epistemology, and Gadamer’s Hermeneutic Phenomenology, offers a relevant, multi-perspectival philosophical foundation for EE research, supporting transactional relationships within contexts of multiple possibilities. Research limitations/implications – Social Constructionism does not necessarily support the individualistic paradigm, as advocated by Constructivists; and the values associated with the former encourage a more collaborative and cooperative approach different from the latter. Practical implications –The paper supports the understanding that applying experiential learning through inter-disciplinary and inter-professional learning is regarded as an approach beneficial for educators, institutions and learners, within the context of EE. Originality/ value – This paper offers a holistic conceptual framework of Social Constructionism that draws on the ‘Gestalt Approach’, and highlights the harmony between the ontological, epistemological and methodological underpinnings of Social Constructionism. The paper demonstrates the relevance of the proposed framework in EE research within the context of an empirical study, which is different in that it focuses on the delivery aspect of EE by considering the views of the providers (educators), an hitherto under-researched area. Paper type – Research paper Key words: Enterprise education, research philosophy, Social Constructionism, relative realism ontology, transactional epistemology, Gadamer’s Hermeneutic Phenomenology, Gestalt approach

Detection, isolation, and analysis of a released Bordetella pertussis product toxic to cultured tracheal cells.

Cultured hamster trachea epithelial cells were selected as an in vitro model system to study Bordetella pertussis in the respiratory tract. DNA synthesis by serum-stimulated tracheal cells, in contrast to other cell types tested, was inhibited by the supernatant from log-phase B. pertussis broth cultures. A sensitive microassay with these tracheal cells permitted the development of a chromatographic purification scheme based on aggregation of the biological activity under salt-free conditions. The active fraction from this first stage of purification caused a dose-dependent inhibition of DNA synthesis without a similar effect on RNA or protein synthesis. Organ cultures of hamster tracheal rings, when exposed to this partially purified fraction, developed epithelial cytopathology comparable to that seen during B. pertussis infection. Ciliary activity showed and eventually ceased as ciliated cells were extruded from the ring, leaving an intact but mostly nonciliated epithelium. Further purification of this biological activity was achieved with preparative-scale high-voltage paper electrophoresis. Based on ninhydrin staining and the radioactive profile of material purified from radiolabeled B. pertussis cultures, four fractions were eluted from the paper by descending chromatography. Only component B caused a dose-dependent inhibition of cultured tracheal cell DNA synthesis and epithelial cytopathology in tracheal rings. Combination experiments also demonstrated enhanced inhibition by component B in the presence of component G (oxidized glutathione), a copurifying molecule from the growth medium. Amino acid analysis (five residues), glycine (two residues), cysteine (two residues), and diaminopimelic acid (one residue), as well as muramic acid and glucosamine

Antigenic and structural differences among six proteins II expressed by a single strain of Neisseria gonorrhoeae.

Gonococci express a family of related outer membrane proteins designated protein II (P.II), which undergo both phase and antigenic variation. Six P.II proteins have been identified in strain FA1090. We developed monoclonal antibodies specific for each P.II protein. Using these antibodies as probes, we purified the six different P.II proteins of this strain. Despite the relatedness of the proteins, we could not purify all of them by a single purification scheme. Four P.II proteins were purified by chromatofocusing, and the remaining two proteins were purified by hydrophobic interaction chromatography on phenyl-Sepharose. The N-terminal amino acid sequence of the proteins showed a high degree of sequence conservation. However, there was variability at specific amino acid residues, giving each P.II protein a unique N-terminal amino acid sequence. Thus P.II proteins of one strain differ among themselves not only in antigenic determinants and primary structure, but also in other characteristics affecting their properties in different chromatographic systems

Wild-Type and Mutant Hemagglutinin Fusion Peptides Alter Bilayer Structure as Well as Kinetics and Activation Thermodynamics of Stalk and Pore Formation Differently: Mechanistic Implications

Viral fusion peptides are short N-terminal regions of type-1 viral fusion proteins that are critical for virus entry. Although the importance of viral fusion peptides in virus-cell membrane fusion is established, little is known about how they function. We report the effects of wild-type (WT) hemagglutinin (HA) fusion peptide and its G1S, G1V, and W14A mutants on the kinetics of poly(ethylene glycol)(PEG)-mediated fusion of small unilamellar vesicles composed of dioleoylphosphatidylcholine, dioleoylphosphatidylethanolamine, sphingomyelin, and cholesterol (molar ratio of 35:30:15:20). Time courses of lipid mixing, content mixing, and content leakage were obtained using fluorescence assays at multiple temperatures and analyzed globally using either a two-step or three-step sequential ensemble model of the fusion process to obtain the rate constant and activation thermodynamics of each step. We also monitored the influence of peptides on bilayer interfacial order, acyl chain order, bilayer free volume, and water penetration. All these data were considered in terms of a recently published mechanistic model for the thermodynamic transition states for each step of the fusion process. We propose that WT peptide catalyzes Step 1 by occupying bilayer regions vacated by acyl chains that protrude into interbilayer space to form the Step 1 transition state. It also uniquely contributes a positive intrinsic curvature to hemi-fused leaflets to eliminate Step 2 and catalyzes Step 3 by destabilizing the highly stressed edges of the hemi-fused microstructures that dominate the ensemble of the intermediate state directly preceding fusion pore formation. Similar arguments explain the catalytic and inhibitory properties of the mutant peptides and support the hypothesis that the membrane-contacting fusion peptide of HA fusion protein is key to its catalytic activity

ACME encoded speG abrogates the unique hypersensitivity of Staphylococcus aureus to exogenous polyamines

Polyamines, including spermine (Spm) and spermidine (Spd), are aliphatic cations that are reportedly synthesized by all living organisms. They exert pleiotropic effects on cells and are required for efficient nucleic acid and protein synthesis. Here, we report that the human pathogen Staphylococcus aureus lacks identifiable polyamine biosynthetic genes, and consequently produces no Spm/Spd or their precursor compounds putrescine and agmatine. Moreover, while supplementing defined medium with polyamines generally enhances bacterial growth, Spm and Spd exert bactericidal effects on S. aureus at physiologic concentrations. Small colony variants specifically lacking menaquinone biosynthesis arose after prolonged Spm exposure and exhibited reduced polyamine-sensitivity. However, other respiratory-defective mutants were no less susceptible to Spm implying menaquinone itself rather than general respiration is required for full Spm-toxicity. Polyamine hypersensitivity distinguishes S. aureus from other bacteria and is exhibited by all tested strains save those belonging to the USA-300 group of Community-Associated Methicillin-Resistant Staphylococcus aureus (CA-MRSA). We identified one gene within the USA-300-specific Arginine Catabolic Mobile Element (ACME) encoding a Spm/Spd N-acetyltransferase that is necessary and sufficient for polyamine resistance. S. aureus encounters significant polyamine levels during infection, however the acquisition of ACME encoded speG allows USA-300 clones to circumvent polyamine-hypersensitivity, a peculiar trait of S. aureus

Accurate quantitation of standard peptides used for quantitative proteomics

MS-based proteomics has become an indispensable tool in system biology generating a need for accurate and precise quantitation of peptide standards. The presented method utilizes ultra performance LC-MS/MS (UPLC-MS/MS) to accurately quantify peptide standards at concentrations of 0.1-10 microM. The ability for accurate quantitation of micro-molar concentrations has the advantages that quantitation can be performed routinely with high precision and the high sensitivity of the method minimizes the amounts required

Why are flare ribbons associated with the spines of magnetic null points generically elongated?

Coronal magnetic null points exist in abundance as demonstrated by extrapolations of the coronal field, and have been inferred to be important for a broad range of energetic events. These null points and their associated separatrix and spine field lines represent discontinuities of the field line mapping, making them preferential locations for reconnection. This field line mapping also exhibits strong gradients adjacent to the separatrix (fan) and spine field lines, that can be analysed using the `squashing factor', $Q$. In this paper we make a detailed analysis of the distribution of $Q$ in the presence of magnetic nulls. While $Q$ is formally infinite on both the spine and fan of the null, the decay of $Q$ away from these structures is shown in general to depend strongly on the null-point structure. For the generic case of a non-radially-symmetric null, $Q$ decays most slowly away from the spine/fan in the direction in which $|{\bf B}|$ increases most slowly. In particular, this demonstrates that the extended, elliptical high-$Q$ halo around the spine footpoints observed by Masson et al. (Astrophys. J., 700, 559, 2009) is a generic feature. This extension of the $Q$ halos around the spine/fan footpoints is important for diagnosing the regions of the photosphere that are magnetically connected to any current layer that forms at the null. In light of this, we discuss how our results can be used to interpret the geometry of observed flare ribbons in `circular ribbon flares', in which typically a coronal null is implicated. We conclude that both the physics in the vicinity of the null and how this is related to the extension of $Q$ away from the spine/fan can be used in tandem to understand observational signatures of reconnection at coronal null points.Comment: Pre-print version of article accepted for publication in Solar Physic

Prognostic Significance of MYC Rearrangement and Translocation Partner in Diffuse Large B-Cell Lymphoma : A Study by the Lunenburg Lymphoma Biomarker Consortium

PURPOSE: MYC rearrangement (MYC-R) occurs in approximately 10% of diffuse large B-cell lymphomas (DLBCLs) and has been associated with poor prognosis in many studies. The impact of MYC-R on prognosis may be influenced by the MYC partner gene (immunoglobulin [IG] or a non-IG gene). We evaluated a large cohort of patients through the Lunenburg Lymphoma Biomarker Consortium to validate the prognostic significance of MYC-R (single-, double-, and triple-hit status) in DLBCL within the context of the MYC partner gene. METHODS: The study cohort included patients with histologically confirmed DLBCL morphology derived from large prospective trials and patient registries in Europe and North America who were uniformly treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone therapy or the like. Fluorescence in situ hybridization for the MYC, BCL2, BCL6, and IG heavy and light chain loci was used, and results were correlated with clinical outcomes. RESULTS: A total of 5,117 patients were identified of whom 2,383 (47%) had biopsy material available to assess for MYC-R. MYC-R was present in 264 (11%) of 2,383 patients and was associated with a significantly shorter progression-free and overall survival, with a strong time-dependent effect within the first 24 months after diagnosis. The adverse prognostic impact of MYC-R was only evident in patients with a concurrent rearrangement of BCL2 and/or BCL6 and an IG partner (hazard ratio, 2.4; 95% CI, 1.6 to 3.6; P < .001). CONCLUSION: The negative prognostic impact of MYC-R in DLBCL is largely observed in patients with MYC double hit/triple-hit disease in which MYC is translocated to an IG partner, and this effect is restricted to the first 2 years after diagnosis. Our results suggest that diagnostic strategies should be adopted to identify this high-risk cohort, and risk-adjusted therapeutic approaches should be refined further