Importance of extra- and intracellular domains of TLR1 and TLR2 in NFkappa B signaling

Recognition of ligands by toll-like receptor (TLR) 2 requires interactions with other TLRs. TLRs form a combinatorial repertoire to discriminate between the diverse microbial ligands. Diversity results from extracellular and intracellular interactions of different TLRs. This paper demonstrates that TLR1 and TLR2 are required for ara-lipoarabinomannan- and tripalmitoyl cysteinyl lipopeptide-stimulated cytokine secretion from mononuclear cells. Confocal microscopy revealed that TLR1 and TLR2 cotranslationally form heterodimeric complexes on the cell surface and in the cytosol. Simultaneous cross-linking of both receptors resulted in ligand-independent signal transduction. Using chimeric TLRs, we found that expression of the extracellular domains along with simultaneous expression of the intracellular domains of both TLRs was necessary to achieve functional signaling. The domains from each receptor did not need to be contained within a single contiguous protein. Chimeric TLR analysis further defined the toll/IL-1R domains as the area of crucial intracellular TLR1-TLR2 interaction

Complement Receptor 1 Is a Sialic Acid-Independent Erythrocyte Receptor of Plasmodium falciparum

Plasmodium falciparum is a highly lethal malaria parasite of humans. A major portion of its life cycle is dedicated to invading and multiplying inside erythrocytes. The molecular mechanisms of erythrocyte invasion are incompletely understood. P. falciparum depends heavily on sialic acid present on glycophorins to invade erythrocytes. However, a significant proportion of laboratory and field isolates are also able to invade erythrocytes in a sialic acid-independent manner. The identity of the erythrocyte sialic acid-independent receptor has been a mystery for decades. We report here that the complement receptor 1 (CR1) is a sialic acid-independent receptor for the invasion of erythrocytes by P. falciparum. We show that soluble CR1 (sCR1) as well as polyclonal and monoclonal antibodies against CR1 inhibit sialic acid-independent invasion in a variety of laboratory strains and wild isolates, and that merozoites interact directly with CR1 on the erythrocyte surface and with sCR1-coated microspheres. Also, the invasion of neuraminidase-treated erythrocytes correlates with the level of CR1 expression. Finally, both sialic acid-independent and dependent strains invade CR1 transgenic mouse erythrocytes preferentially over wild-type erythrocytes but invasion by the latter is more sensitive to neuraminidase. These results suggest that both sialic acid-dependent and independent strains interact with CR1 in the normal red cell during the invasion process. However, only sialic acid-independent strains can do so without the presence of glycophorin sialic acid. Our results close a longstanding and important gap in the understanding of the mechanism of erythrocyte invasion by P. falciparum that will eventually make possible the development of an effective blood stage vaccine

Defective Interfering Viral Particles in Acute Dengue Infections

While much of the genetic variation in RNA viruses arises because of the error-prone nature of their RNA-dependent RNA polymerases, much larger changes may occur as a result of recombination. An extreme example of genetic change is found in defective interfering (DI) viral particles, where large sections of the genome of a parental virus have been deleted and the residual sub-genome fragment is replicated by complementation by co-infecting functional viruses. While most reports of DI particles have referred to studies in vitro, there is some evidence for the presence of DI particles in chronic viral infections in vivo. In this study, short fragments of dengue virus (DENV) RNA containing only key regulatory elements at the 3′ and 5′ ends of the genome were recovered from the sera of patients infected with any of the four DENV serotypes. Identical RNA fragments were detected in the supernatant from cultures of Aedes mosquito cells that were infected by the addition of sera from dengue patients, suggesting that the sub-genomic RNA might be transmitted between human and mosquito hosts in defective interfering (DI) viral particles. In vitro transcribed sub-genomic RNA corresponding to that detected in vivo could be packaged in virus like particles in the presence of wild type virus and transmitted for at least three passages in cell culture. DENV preparations enriched for these putative DI particles reduced the yield of wild type dengue virus following co-infections of C6–36 cells. This is the first report of DI particles in an acute arboviral infection in nature. The internal genomic deletions described here are the most extensive defects observed in DENV and may be part of a much broader disease attenuating process that is mediated by defective viruses

Evolution of Multidrug Resistance during Staphylococcus aureus Infection Involves Mutation of the Essential Two Component Regulator WalKR

Antimicrobial resistance in Staphylococcus aureus is a major public health threat, compounded by emergence of strains with resistance to vancomycin and daptomycin, both last line antimicrobials. Here we have performed high throughput DNA sequencing and comparative genomics for five clinical pairs of vancomycin-susceptible (VSSA) and vancomycin-intermediate ST239 S. aureus (VISA); each pair isolated before and after vancomycin treatment failure. These comparisons revealed a frequent pattern of mutation among the VISA strains within the essential walKR two-component regulatory locus involved in control of cell wall metabolism. We then conducted bi-directional allelic exchange experiments in our clinical VSSA and VISA strains and showed that single nucleotide substitutions within either walK or walR lead to co-resistance to vancomycin and daptomycin, and caused the typical cell wall thickening observed in resistant clinical isolates. Ion Torrent genome sequencing confirmed no additional regulatory mutations had been introduced into either the walR or walK VISA mutants during the allelic exchange process. However, two potential compensatory mutations were detected within putative transport genes for the walK mutant. The minimal genetic changes in either walK or walR also attenuated virulence, reduced biofilm formation, and led to consistent transcriptional changes that suggest an important role for this regulator in control of central metabolism. This study highlights the dramatic impacts of single mutations that arise during persistent S. aureus infections and demonstrates the role played by walKR to increase drug resistance, control metabolism and alter the virulence potential of this pathogen

Структура електромагнітного поля ферит-діелектричного резонатора

Introduction. The considered several works explore the question of electromagnetic resonance ferrite and dielectric resonators, the influence of electrodynamics system on the spectrum of magnetostatic oscillations ferrite resonator, the influence of metal wall on the spectrum of cylindrical dielectric resonator vibrations. Calculations of the electromagnetic field ferrite-dielectric resonator. The expressions for the components of the electromagnetic field outside the ferrite resonator for dielectric spectrum of fluctuations are obtained explicitly. The dependence of components of the external electromagnetic field on the coordinates r and θ for the main type of dielectric fluctuations spherical dielectric resonator H110 is calculated. The graphs of these dependencies are constructed. The comparison of expressions for the components of the electromagnetic field outside the ferrite resonator for dielectric spectrum fluctuations is conducted. These components are calculated using the technique of electromagnetic field excitation polarization currents with known expressions obtained by other methods. Conclusions. The investigation of the electromagnetic field ferrite resonator structure as a particular case of ferrite-dielectric resonator is conducted. The investigation of the external electromagnetic fields structure is carried out for the case of the main type of dielectric fluctuations using the method of calculating the excitation polarization currents of these fields. Polarization currents are found from the expression for the internal electromagnetic fields for basic type oscillation of ferrite resonator H110.В работе получены выражения для компонентов электромагнитного поля снаружи ферритового резонатора для диэлектрического спектра колебаний в явном виде. Рассчитаны зависимости компонентов внешнего электромагнитного поля от координат r и θ для основного вида диэлектрических колебаний сферического диэлектрического резонатора Н110 и построены графики этих зависимостей. Проведено сравнение выражений для компонентов электромагнитного поля снаружи ферритового резонатора для диэлектрического спектра колебаний, рассчитанных с помощью методики возбуждения электромагнитного поля токами поляризации, с известными выражениями, полученными другими методами.В роботі отримані вирази для компонентів електромагнітного поля ззовні феритового резонатора для діелектричного спектру коливань в явному вигляді. Розраховані залежності компонентів зовнішнього електромагнітного поля від координат r та θ для основного виду діелектричних коливань сферичного діелектричного резонатора Н110 та побудовані графіки цих залежностей. Проведено порівняння виразів для компонентів електромагнітного поля назовні феритового резонатора для діелектричного спектру коливань, розрахованих за допомогою методики збудження електромагнітного поля струмами поляризації, з відомими виразами, отриманими іншими методами

Bilaterale Vestibulopathie der Otolithenorgane

Einführung: Die bilaterale Vestibulopathie ist eine seltene Erkrankung des Gleichgewichtsorgans, die mit einer pathologischen thermischen Prüfung gesichert wird und mit Oszillopsien einhergeht. Heute ist es möglich die Rezeptorfunktion objektiv, seiten- und rezeptorspezifisch unter zeit- und frequenzdynamischen Aspekten zu erfassen, so dass, neben den Bogengängen, auch die Otolithenfunktion in die Definition einer bilateralen Vestibulopathie einbezogen werden muss.Fall: Wir berichten über eine 75-jährige Patientin mit seit 2003 bestehendem Schwankschwindel und daraus resultierenden Stürzen mit Verletzungsfolge. Die thermische und rotatorische Vestibulardiagnostik, wie auch der Video-Kopfimpulstest für alle Bogengänge ergaben keine pathologischen Befunde. Im Tonaudiogramm zeigte sich eine symmetrische, pancochleäre Schallempfindungsstörung beiderseits bis 50 dB. Zur Einschätzung der Otolithenfunktion wurden cervikale und okuläre VEMPs abgeleitet, die bilateral fehlten. Das führte zur Diagnose einer bilateralen Vestibulopathie der Otolithenorgane mit Affektion von Sakkulus und Utrikulus. Diese war am ehesten auf die intravenöse Gentamicinapplikation bei Pneumonie im Jahre 2003 zurückzuführen. Ein individuelles Training führte zur Besserung der Symptomatik.Schlussfolgerung: Eine bilaterale Vestibulopathie der Otolithenorgane muss bei gentamicininduzierten Störungen berücksichtigt werden. Die moderne Rezeptorfunktionsdiagnostik erlaubt gentamicininduzierte Störungen zu lokalisieren.Der Erstautor gibt keinen Interessenkonflikt an