Differential effect of dsbA and dsbC mutations on extracellular enzyme secretion in Erwinia chrysanthemi

An Erwinia chrysanthemi gene able to complement an Escherichia coli dsbA mutation has been cloned and sequenced. This gene codes for a periplasmic protein with disulphide isomerase activity that has 69% identity and 94% similarity with the E. coli DsbA protein. An E. chrysanthemi dsbA-uidA fusion mutant has been constructed. dsbA expression seems to be constitutive. This mutant has multiple phenotypes resulting from the absence of disulphide bond formation in periplasmic and secreted proteins. Pectate lyases and the cellulase EGZ are rapidly degraded in the periplasm of the dsbA mutant. E. chrysanthemi synthesizes another periplasmic protein with disulphide isomerase activity, namely DsbC. The dsbC gene introduced on a multicopy plasmid in a dsbA mutant was only partially able to restore EGZ secretion, indicating that even if DsbA and DsbC possess disulphide oxydoreductase activity, they are not completely interchangeable. Moreover, pectate lyases expressed in an E. coli dsbA mutant were very instable but their stability was unaffected in a dsbC mutant. These results indicate that DsbA and DsbC could have different substrate specificities.     

Differential expression and tumor necrosis factor‐mediated regulation of TNFRSF11b/osteoprotegerin production by human melanomas

Tumors escape host immune responses, in part, through the release of immunomodulatory factors and decoy receptors into their microenvironment. Several cancers express surface‐bound and soluble members of the tumor necrosis factor (TNF) receptor superfamily, including TNFRSF11b/osteoprotegerin (OPG). In its physiologic role, OPG regulates bone remodeling through competition for osteoclast‐activating cytokines and protects newly forming bone from T cell‐mediated apoptosis. In multiple tumor types, OPG production is associated with an aggressive phenotype and increased metastasis to bone, but no study has examined OPG production in human metastatic melanoma. We demonstrate that a significant proportion of human metastatic melanomas constitutively produces OPG through a mechanism governed by membrane‐bound TNF‐α signaling through TNF receptor 1 (TNFR1). These observations both define a specific mechanism that regulates melanoma production of OPG and establish a new molecular target for the therapeutic regulation of OPG.     

Characterization of Metabolic,Diffusion, and Perfusion Properties in GBM: Contrast-Enhancing versus Non-Enhancing Tumor

BACKGROUND: Although the contrast-enhancing (CE) lesion on T₁-weighted MR images is widely used as a surrogate for glioblastoma (GBM), there are also non-enhancing regions of infiltrative tumor within the T₂-weighted lesion, which elude radiologic detection. Because non-enhancing GBM (Enh?) challenges clinical patient management as latent disease, this study sought to characterize ex vivo metabolic profiles from Enh? and CE GBM (Enh+) samples, alongside histological and in vivo MR parameters, to assist in defining criteria for estimating total tumor burden. Methods: Fifty-six patients with newly diagnosed GBM received a multi-parametric pre-surgical MR examination. Targets for obtaining image-guided tissue samples were defined based on in vivo parameters that were suspicious for tumor. The actual location from where tissue samples were obtained was recorded, and half of each sample was analyzed for histopathology while the other half was scanned using HR-MAS spectroscopy. Results: The Enh+ and Enh? tumor samples demonstrated comparable mitotic activity, but also significant heterogeneity in microvascular morphology. Ex vivo spectroscopic parameters indicated similar levels of total choline and N-acetylaspartate between these contrast-based radiographic subtypes of GBM, and characteristic differences in the levels of myo-inositol, creatine/phosphocreatine, and phosphoethanolamine. Analysis of in vivo parameters at the sample locations were consistent with histological and ex vivo metabolic data. CONCLUSIONS: The similarity between ex vivo levels of choline and NAA, and between in vivo levels of choline, NAA and nADC in Enh+ and Enh? tumor, indicate that these parameters can be used in defining non-invasive metrics of total tumor burden for patients with GBM.     

Introducing quality measures in an academic research consortium: Lessons and recommendation from implementing an ad hoc quality management system for organ model research

Lessons from implementing quality control systems in an academic research consortium to improve Good Scientific Practice and reproducibility. Subject Categories: Microbiology, Virology & Host Pathogen Interaction, Science Policy & Publishing

Low reproducibility rates within biomedical research negatively impact productivity and translation. One promising approach to enhance the transfer of robust results from preclinical research into clinically relevant and transferable data is the systematic implementation of quality measures in daily laboratory routines.

Although many universities expect their scientists to adhere to GSPs, they often neither systematically support, nor monitor the quality of their research activities.

Today''s fast‐evolving research environment needs effective quality measures to ensure reproducibility and data integrity (Macleod et al, ²⁰¹⁴; Begley et al, ²⁰¹⁵; Begley & Ioannidis, ²⁰¹⁵; Baker, ²⁰¹⁶). Academic research institutions and laboratories may be as committed to good scientific practices (GSPs) as their counterparts in the biotech and pharmaceutical industry but operate largely without clearly defined standards (Bespalov et al, ²⁰²¹; Emmerich et al, ²⁰²¹). Although many universities expect their scientists to adhere to GSPs, they often neither systematically support, nor monitor the quality of their research activities. Peer review of publications is still regarded as the primary validation of quality control in academic research. However, reviewers only assess work after it has been performed—often over years—and interventions in the experimental process are thus no longer possible.The reasons for the lack of dedicated quality management (QM) implementations in academic laboratories include an anticipated overload of regulatory tasks that could negatively affect productivity, concerns about the loss of scientific freedom, and importantly, limited resources in academia and academic funding schemes.     

Preclinical Pharmacokinetic Studies of the Tritium Labelled D-Enantiomeric Peptide D3 Developed for the Treatment of Alzheimer′s Disease

Targeting toxic amyloid beta (Aβ) oligomers is currently a very attractive drug development strategy for treatment of Alzheimer´s disease. Using mirror-image phage display against Aβ1-42, we have previously identified the fully D-enantiomeric peptide D3, which is able to eliminate Aβ oligomers and has proven therapeutic potential in transgenic Alzheimer´s disease animal models. However, there is little information on the pharmacokinetic behaviour of D-enantiomeric peptides in general. Therefore, we conducted experiments with the tritium labelled D-peptide D3 (³H-D3) in mice with different administration routes to study its distribution in liver, kidney, brain, plasma and gastrointestinal tract, as well as its bioavailability by i.p. and p.o. administration. In addition, we investigated the metabolic stability in liver microsomes, mouse plasma, brain, liver and kidney homogenates, and estimated the plasma protein binding. Based on its high stability and long biological half-life, our pharmacokinetic results support the therapeutic potential of D-peptides in general, with D3 being a new promising drug candidate for Alzheimer´s disease treatment.     

Structures chimiques et propriétés biologiques de quelques substances identifiées chez l'abeille

Résumé Cette revue fait le point de connaissances concernant les propriétés biologiques des différentes substances lipidiques isolées des ouvrières et des reines d'abeilles. On insiste plus particulièrement sur la phérormone I inhibitrice de la construction des cellules royales, et sur le complexe phérormone I + phérormone II, attractif pour les jeunes abeilles ouvrières, et inhibiteur de leur oveogénèse.

---

Summary This constitutes an up-to-date review of our knowledge concerning the biological properties of the various lipid fractions isolated from queen and worker honeybees. Particular attention is given to pherormone I, which inhibits queen rearing, and to the mixture pherormone I + pherormone II, which is an attractant for young worker bees, and inhibits ovogenesis.

---

Zusammenfassung Diese Arbeit bildet eine Zusammenfassung unserer heutigen Kenntnisse über die verschiedenen Lipid Fraktionnen welche aus Bienenk?niginnen und Arbeiterinnen isoliert wurden. Besondere Aufmerksamkeit wird dem Pherormon I zugewendet, das den Aufbau der Weiselzellen hemmt, sowie dem Pherormon I + Pherormon II Komplexe, das als Lockstoffe auf die Arbeiterinnen wirkt, und die Eierbildung bei denselben unterbildet.

     

Localisation génétique et caractérisation biochimique de mutations affectant le gène de structure de l'hydrolyase altronique chez Escherichia coli K 12

Molecular Genetics and Genomics - Mutants of E. coli specifically deficient for the enzyme altronic hydrolyase have been isolated. These strains are unable to metabolize galacturonate but still...