Cx31.1 can selectively intermix with co-expressed connexins to facilitate its assembly into gap junctions

Connexins are channel-forming proteins that function to facilitate gap junctional intercellular communication. Here, we use dual cell voltage clamp and dye transfer studies to corroborate past findings showing that Cx31.1 (encoded by GJB5) is defective in gap junction channel formation, illustrating that Cx31.1 alone does not form functional gap junction channels in connexin-deficient mammalian cells. Rather Cx31.1 transiently localizes to the secretory pathway with a subpopulation reaching the cell surface, which is rarely seen in puncta reminiscent of gap junctions. Intracellular retained Cx31.1 was subject to degradation as Cx31.1 accumulated in the presence of proteasomal inhibition, had a faster turnover when Cx43 was present and ultimately reached lysosomes. Although intracellularly retained Cx31.1 was found to interact with Cx43, this interaction did not rescue its delivery to the cell surface. Conversely, the co-expression of Cx31 dramatically rescued the assembly of Cx31.1 into gap junctions where gap junction-mediated dye transfer was enhanced. Collectively, our results indicate that the localization and functional status of Cx31.1 is altered through selective interplay with co-expressed connexins, perhaps suggesting Cx31.1 is a key regulator of intercellular signaling in keratinocytes.

Potency and durability of T and B cell immune responses after homologous and heterologous vector delivery of a trimer-stabilized, membrane-displayed HIV-1 clade ConC Env protein

Introduction

The generation of an HIV-1 vaccine able to induce long-lasting protective immunity remains a main challenge. Here, we aimed to modify next-generation soluble, prefusion-stabilized, close-to-native, glycan-engineered clade C gp140 envelope (Env) trimers (sC23v4 KIKO and ConCv5 KIKO) for optimal display on the cell surface following homologous or heterologous vector delivery.

Methods

A combination of the following modifications scored best regarding the preservation of closed, native-like Env trimer conformation and antigenicity when using a panel of selected broadly neutralizing (bnAb) and non-neutralizing (nnAb) monoclonal antibodies for flow cytometry: i) replacing the natural cleavage site with a native flexible linker and introducing a single amino acid substitution to prevent CD4 binding (*), ii) fusing a heterologous VSV-G-derived transmembrane moiety to the gp140 C-terminus, and iii) deleting six residues proximal to the membrane.

Results

When delivering membrane-tethered sC23v4 KIKO* and ConCv5 KIKO* via DNA, VSV-GP, and NYVAC vectors, the two native-like Env trimers provide differential antigenicity profiles. Whereas such patterns were largely consistent among the different vectors for either Env trimer, the membrane-tethered ConCv5 KIKO* trimer adopted a more closed and native-like structure than sC23v4 KIKO*. In immunized mice, VSV-GP and NYVAC vectors expressing the membrane-tethered ConCv5 KIKO* administered in prime/boost combination were the most effective regimens for the priming of Env-specific CD4 T cells among all tested combinations. The subsequent booster administration of trimeric ConCv5 KIKO* Env protein preserved the T cell activation levels between groups. The evaluation of the HIV-1-specific humoral responses induced in the different immunization groups after protein boosts showed that the various prime/boost protocols elicited broad and potent antibody responses, preferentially of a Th1-associated IgG2a subclass, and that the obtained antibody levels remained high at the memory phase.

Discussion

In summary, we provide a feasible strategy to display multiple copies of native-like Env trimers on the cell surface, which translates into efficient priming of sustained CD4+ T cell responses after vector delivery as well as broad, potent, and sustained antibody responses following booster immunizations with the homologous, prefusion-stabilized, close-to-native ConCv5 KIKO* gp140 Env trimer.

Diversity in connexin biology

Over 35 years ago the cell biology community was introduced to connexins as the subunit employed to assemble semicrystalline clusters of intercellular channels that had been well described morphologically as gap junctions. The decade that followed would see knowledge of the unexpectedly large 21-member human connexin family grow to reflect unique and overlapping expression patterns in all organ systems. While connexin biology initially focused on their role in constructing highly regulated intercellular channels, this was destined to change as discoveries revealed that connexin hemichannels at the cell surface had novel roles in many cell types, especially when considering connexin pathologies. Acceptance of connexins as having bifunctional channel properties was initially met with some resistance, which has given way in recent years to the premise that connexins have multifunctional properties. Depending on the connexin isoform and cell of origin, connexins have wide-ranging half-lives that vary from a couple of hours to the life expectancy of the cell. Diversity in connexin channel characteristics and molecular properties were further revealed by X-ray crystallography and single-particle cryo-EM. New avenues have seen connexins or connexin fragments playing roles in cell adhesion, tunneling nanotubes, extracellular vesicles, mitochondrial membranes, transcription regulation, and in other emerging cellular functions. These discoveries were largely linked to Cx43, which is prominent in most human organs. Here, we will review the evolution of knowledge on connexin expression in human adults and more recent evidence linking connexins to a highly diverse array of cellular functions.

Assessing immunogenicity barriers of the HIV-1 envelope trimer

Understanding the balance between epitope shielding and accessibility on HIV-1 envelope (Env) trimers is essential to guide immunogen selection for broadly neutralizing antibody (bnAb) based vaccines. To investigate the antigenic space of Env immunogens, we created a strategy based on synthetic, high diversity, Designed Ankyrin Repeat Protein (DARPin) libraries. We show that DARPin Antigenicity Analysis (DANA), a purely in vitro screening tool, has the capability to extrapolate relevant information of antigenic properties of Env immunogens. DANA screens of stabilized, soluble Env trimers revealed that stronger trimer stabilization led to the selection of highly mutated DARPins with length variations and framework mutations mirroring observations made for bnAbs. By mimicking heterotypic prime-boost immunization regimens, DANA may be used to select immunogen combinations that favor the selection of trimer-reactive binders. This positions DANA as a versatile strategy for distilling fundamental antigenic features of immunogens, complementary to preclinical immunogenicity testing.

GJB4 variants linked to skin disease exhibit a trafficking deficiency en route to gap junction formation that can be restored by co-expression of select connexins

Epidermal keratinocytes are enriched with at least nine connexins that are key regulators of epidermal homeostasis. The role of Cx30.3 in keratinocytes and epidermal health became evident when fourteen autosomal dominant mutations in the Cx30.3-encoding GJB4 gene were linked to a rare and incurable skin disorder called erythrokeratodermia variabilis et progressiva (EKVP). While these variants are linked to EKVP, they remain largely uncharacterized hindering therapeutic options. In this study, we characterize the expression and functional status of three EKVP-linked Cx30.3 mutants (G12D, T85P, and F189Y) in tissue-relevant and differentiation-competent rat epidermal keratinocytes. We found that GFP-tagged Cx30.3 mutants were non-functional likely due to their impaired trafficking and primary entrapment within the endoplasmic reticulum (ER). However, all mutants failed to increase BiP/GRP78 levels suggesting they were not inducing an unfolded protein response. FLAG-tagged Cx30.3 mutants were also trafficking impaired yet occasionally exhibited some capacity to assemble into gap junctions. The pathological impact of these mutants may extend beyond their trafficking deficiencies as keratinocytes expressing FLAG-tagged Cx30.3 mutants exhibited increased propidium iodide uptake in the absence of divalent cations. Attempts to rescue the delivery of trafficking impaired GFP-tagged Cx30.3 mutants into gap junctions by chemical chaperone treatment were ineffective. However, co-expression of wild type Cx30.3 greatly enhanced the assembly of Cx30.3 mutants into gap junctions, although endogenous levels of Cx30.3 do not appear to prevent the skin pathology found in patients harboring these autosomal dominant mutations. In addition, a spectrum of connexin isoforms (Cx26, Cx30, and Cx43) exhibited the differential ability to trans-dominantly rescue the assembly of GFP-tagged Cx30.3 mutants into gap junctions suggesting a broad range of connexins found in keratinocytes may favourably interact with Cx30.3 mutants. We conclude that selective upregulation of compatible wild type connexins in keratinocytes may have potential therapeutic value in rescuing epidermal defects invoked by Cx30.3 EKVP-linked mutants.

Stepwise Conformational Stabilization of a HIV-1 Clade C Consensus Envelope Trimer Immunogen Impacts the Profile of Vaccine-Induced Antibody Responses

Stabilization of the HIV-1 Envelope glycoprotein trimer (Env) in its native pre-fusion closed conformation is regarded as one of several requirements for the induction of neutralizing antibody (nAb) responses, which, in turn, will most likely be a prerequisite for the development of an efficacious preventive vaccine. Here, we systematically analyzed how the stepwise stabilization of a clade C consensus (ConC) Env immunogen impacts biochemical and biophysical protein traits such as antigenicity, thermal stability, structural integrity, and particle size distribution. The increasing degree of conformational rigidification positively correlates with favorable protein characteristics, leading to optimized homogeneity of the protein preparations, increased thermal stability, and an overall favorable binding profile of structure-dependent broadly neutralizing antibodies (bnAbs) and non-neutralizing antibodies (non-nAbs). We confirmed that increasing the structural integrity and stability of the Env trimers positively correlates with the quality of induced antibody responses by the immunogens. These and other data contribute to the selection of ConCv5 KIKO as novel Env immunogens for use within the European Union's H2020 Research Consortium EHVA (European HIV Alliance) for further preclinical analysis and phase 1 clinical development.

Augmenting the Immune Response against a Stabilized HIV-1 Clade C Envelope Trimer by Silica Nanoparticle Delivery

The delivery of HIV-1 envelope (Env) trimer-based immunogens on the surface of nanoparticles holds promise to promote immunogenicity with the aim of inducing a potent, durable and broad neutralizing antibody (bnAb) response. Towards that goal, we examined the covalent conjugation of Env to 100 nm and 200 nm silica nanoparticles (SiNPs) to optimize conjugation density and attachment stability. Env was redesigned to enable site-specific cysteine-mediated covalent conjugation while maintaining its structural integrity and antigenicity. Env was anchored to different sized SiNPs with a calculated spacing of 15 nm between adjacent trimers. Both particle sizes exhibited high in vitro stability over a seven-day period. After attachment, 100 nm particles showed better colloidal stability compared to 200 nm particles. Importantly, the antigenic profile of Env was not impaired by surface attachment, indicating that the quaternary structure was maintained. In vitro Env uptake by dendritic cells was significantly enhanced when Env was delivered on the surface of nanoparticles compared to soluble Env. Furthermore, multivalent Env displayed efficiently activated B cells even at Env concentrations in the low nanomolar range. In mice, antibody responses to nanoparticle-coupled Env were stronger compared to the free protein and had equivalent effects at lower doses and without adjuvant.

[Pager-supported waiting time management in a university hospital ENT outpatient department : A pilot project for more distance and more comfort]

Hintergrund

Aufgrund der Pandemie mit dem neuartigen Coronavirus (SARS-CoV-2) sollte überall auf ausreichend Abstand zwischen Personen geachtet werden, insbesondere auch in Wartebereichen medizinischer Versorgungseinrichtungen. Bei oftmals eingeschränkten räumlichen Kapazitäten ist dies jedoch nicht immer problemlos realisierbar.

Ziel der Arbeit

Wir untersuchten die Möglichkeit, mittels eines Pagersystems den Patienten unserer HNO-Ambulanz eine Wartezeit außerhalb des eigentlichen Wartebereichs zu ermöglichen, um damit die Anzahl der Patienten im Wartebereich zu reduzieren, und die Einhaltung der Abstandsregeln zu gewährleisten.

Material und Methoden

In einer Zeitspanne von 12,5 Wochen (Beginn 04.06.2020, Ende 31.08.2020) erfolgte die Ausgabe von Pagern an die Patienten unserer HNO-Ambulanz. Teilnehmenden Patienten war es damit möglich, sich während der Wartezeit auf dem gesamten Klinikgelände frei zu bewegen. Der Pager wurde 10–15 min vor dem Termin aktiviert, und der Patient damit zurück in die HNO-Ambulanz gerufen. Mittels Fragebögen erfolgte eine Evaluation des Systems, um die Akzeptanz und Zufriedenheit der Patienten zu eruieren.

Ergebnisse

137 Fragebögen wurden analysiert, hierbei zeigte sich eine Zufriedenheit mit dem System – nicht nur, was die Einhaltung der Abstandsregeln betrifft, sondern auch bzgl. eines höheren Komforts während der Wartezeit.

Schlussfolgerung

Die Einführung eines Pagersystems für Patienten führt neben der Wahrung der Hygiene- und Abstandsregeln auch zu einer Erhöhung des Komforts während der (häufig nicht zu vermeidenden) Wartezeit für die Patienten in der universitären Ambulanz einer HNO-Klinik. Daher erscheint ein langfristiger Einsatz eines solchen Systems vielversprechend.

Patients with breakthrough tick-borne encephalitis suffer a more severe clinical course and display extensive magnetic resonance imaging changes

Background and purpose

Tick‐borne encephalitis (TBE) is a common viral disease in central Europe and Asia. Severe or even lethal neurological symptoms may ensue. With limited therapeutic options, active vaccination against the TBE virus (TBEV) is strongly recommended in endemic areas. A systematic analysis of the clinical picture and cerebral imaging findings associated with TBE was conducted with particular focus on patients who acquired TBE despite previous vaccination.

Methods

A cohort of 52 patients with serologically proven TBE treated at our centre in a 10‐year period who received at least one cerebral magnetic resonance imaging (MRI) was retrospectively described. Extension of MRI changes was systematically assessed by an experienced neuroradiologist. Standard statistical procedures were performed.

Results

Fifty‐two patients with a definite serological diagnosis of TBE were included. The most common presentation was encephalitis (67%). MRI showed TBE‐associated parenchymal lesions in 33% of all patients. Sites of predilection included the periaqueductal grey, the thalamus and the brainstem. Ten patients had received at least one prior active or passive TBEV immunization. All of these had a maximal Rankin Scale score of at least 4. The median number of affected anatomical regions on MRI was significantly higher than in the non‐vaccinated cohort.

Conclusions

To our knowledge, this is the first study systematically describing the peculiarities of MRI in patients vaccinated against TBE. In addition to a severe clinical course, they exhibit more extensive MRI lesions than a non‐vaccinated cohort. Possible reasons for these findings include incomplete seroconversion, more virulent TBEV strains or antibody‐dependent enhancement.

Adenosine stress CMR perfusion imaging of the temporal evolution of perfusion defects in a porcine model of progressive obstructive coronary artery occlusion

Adenosine stress CMR perfusion imaging can quantify absolute perfusion and myocardial perfusion reserve (MPR) in coronary artery disease (CAD) with higher spatial resolution than positron emission tomography, the only clinically available technique for quantitative myocardial perfusion imaging. While porcine models of CAD are excellent for studying perfusion abnormalities in chronic CAD, to date there are a limited number of studies that use quantitative perfusion for evaluation. Therefore, we developed an adenosine stress CMR protocol to evaluate the temporal evolution of perfusion defects in a porcine model of progressive obstructive CAD. 10 Yucatan minipigs underwent placement of an ameroid occluder around the left circumflex artery (LCX) to induce a progressive chronic coronary obstruction. Four animals underwent a hemodynamic dose range experiment to determine the adenosine dose inducing maximal hyperemia. Each animal had a CMR examination, including stress/rest spiral quantitative perfusion imaging at baseline and 1, 3, and 6 weeks. Late gadolinium enhancement images determined the presence of myocardial infarction, if any existed. Pixelwise quantitative perfusion maps were generated using Fermi deconvolution. The results were statistically analyzed with a repeated mixed measures model to block for physiological variation between the animals. Five animals developed myocardial infarction by 3 weeks, while three developed ischemia without an infarction. The perfusion defects were located in the inferolateral myocardium in the perfusion territory of the LCX. Stress perfusion values were higher in remote segments than both the infarcted and ischemic segments (p < 0.01). MPR values were significantly greater in the remote segments than infarcted and ischemic segments (p < 0.01). While the MPR decreased in all segments, the MPR recovered by the sixth week in the remote regions. We developed a model of progressive CAD and evaluated the temporal evolution of the development of quantitative perfusion defects. This model will serve as a platform for understanding the development of perfusion abnormalities in chronic occlusive CAD.

Perfil metabólico de vacas Holandês e mestiças Holandês x Jersey no periparto

RESUMO O objetivo do presente trabalho foi determinar e comparar o perfil metabólico de vacas Holandês (H) e mestiças Holandês x Jersey (HxJ) no periparto. Avaliaram-se 24 vacas, sendo 11 vacas Holandês e 13 mestiças Holandês x Jersey. Semanalmente, coletou-se sangue para a determinação das concentrações séricas de glicose, beta-hidroxibutirato (BHB), proteína total, albumina, aspartato aminotransferase (AST), creatinoquinase (CK), cálcio total, cálcio iônico, magnésio, fósforo inorgânico e colesterol. Avaliou-se também o peso vivo e o escore de condição corporal (ECC). Os dados foram submetidos à análise de variância com medidas repetidas no tempo. As vacas Holandês apresentaram maior peso vivo. Não houve diferença entre os grupamentos genéticos para ECC. Foi observada tendência de maiores concentrações séricas de BHB, AST e maior concentração de cálcio iônico em vacas mestiças Holandês x Jersey. Vacas mestiças Holandês x Jersey e Holandês apresentaram perfil energético similar durante o período de transição pré e pós-parto na maioria dos indicadores, com exceção do cálcio, que foi maior nas vacas mestiças, e do fósforo, que foi superior nas vacas Holandês.

Comparison of the lattice-Boltzmann model with the finite-difference time-domain method for electrodynamics

A three-dimensional lattice-Boltzmann model (LBM) for the simulation of the Maxwell equations is presented. The inclusion of media follows an extension of a special limit described in the literature which is applicable to this LBM and does not harm the stability of simulations. The focus of the present study lies on the properties of numerical accuracy and stability of the LBM in comparison to the standard finite-difference time-domain (FDTD) method based on Yee's method. Typical examples, often investigated in the context of numerical simulations, are considered. These include the propagation of electrodynamic (EM) fields in one- and three-dimensional systems. Results of this simulations are compared to the ones of their theoretical predictions. Further on, long-time simulations are done in systems with periodic boundary conditions to check if the total energy is conserved. To investigate the effect of the numeric impedance, the propagation of an EM pulse is monitored spatially and temporarily in a two-dimensional system. The simulation results indicate, in contrast to the one obtained from the FDTD method, that the presented LBM does fulfill the expected energy conservation and is not effected by the numerical impedance. This LBM therefore represents a valuable alternative for the simulation of EM problems like long-time simulations by avoiding intrinsic properties the FDTD method suffers from.

The presence of occipital hair in the pilonidal sinus cavity-a triple approach to proof

PURPOSE

Hair in the pilonidal sinus is not growing within the sinus cavity, as hair follicles are not present there. Not few pilonidal patients do not have intergluteal hair, which is said to be the causative agent of folliculitis and pilonidal genesis. So, what is the real source of the hair forming the typical pilonidal hair nest?

METHODS

A trifold approach was used: First, axial hair strength testing of pilonidal hair and body hair harvested from head, lower back (glabella sacralis), and cranial third of intergluteal fold. Hair strength match was compared clinically. Second, comparative morphological examination by expert forensic biologist of hair from sinus and dorsal body hair. Third, statistical Bayesian classification of every single sinus hair based on its strength was done to determine the most probable region of origin.

RESULTS

Using clinical hair strength comparison, in 13/20 patients, head hair is the stiffest hair, followed by intergluteal hair. Only in 6/20 patients, this is the case with hair from the glabella sacralis. According to comparative morphological comparison, a minimum of 5 of 13 hair nests with possible hair allocation examined contain hair from the occiput. In 5/18 nests, hair could not be determined to a specific location though. Statistical classification with correction for multiple testing shows that 2 nests have hair samples that are at least 100 times more probable to originate from head or lower back than from intergluteal fold.

CONCLUSION

We saw our null hypothesis that "hair in the sinus cavity is from the intergluteal region" rejected by each of three different approaches. There is strong evidence that occipital hair is present regularly in pilonidal sinus nests. We should start thinking of occipital hair as an important hair source for the development of the pilonidal hair nest.

Stable lattice Boltzmann model for Maxwell equations in media

The present work shows a method for stable simulations via the lattice Boltzmann (LB) model for electromagnetic waves (EM) transiting homogeneous media. LB models for such media were already presented in the literature, but they suffer from numerical instability when the media transitions are sharp. We use one of these models in the limit of pure vacuum derived from Liu and Yan [Appl. Math.

MODEL

38, 1710 (2014)AMMODL0307-904X10.1016/j.apm.2013.09.009] and apply an extension that treats the effects of polarization and magnetization separately. We show simulations of simple examples in which EM waves travel into media to quantify error scaling, stability, accuracy, and time scaling. For conductive media, we use the Strang splitting and check the simulations accuracy at the example of the skin effect. Like pure EM propagation, the error for the static limits, which are constructed with a current density added in a first-order scheme, can be less than 1%. The presented method is an easily implemented alternative for the stabilization of simulation for EM waves propagating in spatially complex structured media properties and arbitrary transitions.

The Proteome of Native Adult Müller Glial Cells From Murine Retina

To date, the proteomic profiling of Müller cells, the dominant macroglia of the retina, has been hampered because of the absence of suitable enrichment methods. We established a novel protocol to isolate native, intact Müller cells from adult murine retinae at excellent purity which retain in situ morphology and are well suited for proteomic analyses. Two different strategies of sample preparation - an in StageTips (iST) and a subcellular fractionation approach including cell surface protein profiling were used for quantitative liquid chromatography-mass spectrometry (LC-MSMS) comparing Müller cell-enriched to depleted neuronal fractions. Pathway enrichment analyses on both data sets enabled us to identify Müller cell-specific functions which included focal adhesion kinase signaling, signal transduction mediated by calcium as second messenger, transmembrane neurotransmitter transport and antioxidant activity. Pathways associated with RNA processing, cellular respiration and phototransduction were enriched in the neuronal subpopulation. Proteomic results were validated for selected Müller cell genes by quantitative real time PCR, confirming the high expression levels of numerous members of the angiogenic and anti-inflammatory annexins and antioxidant enzymes (e.g. paraoxonase 2, peroxiredoxin 1, 4 and 6). Finally, the significant enrichment of antioxidant proteins in Müller cells was confirmed by measurements on vital retinal cells using the oxidative stress indicator CM-H2DCFDA. In contrast to photoreceptors or bipolar cells, Müller cells were most efficiently protected against H₂O₂-induced reactive oxygen species formation, which is in line with the protein repertoire identified in the proteomic profiling. Our novel approach to isolate intact glial cells from adult retina in combination with proteomic profiling enabled the identification of novel Müller glia specific proteins, which were validated as markers and for their functional impact in glial physiology. This provides the basis to allow the discovery of novel glial specializations and will enable us to elucidate the role of Müller cells in retinal pathologies — a topic still controversially discussed.

Beyond Gatekeepers of Knowledge: Scholarly Communication Practices of Academic Librarians and Archivists at ARL Institutions

Librarians and archivists are intimately involved in scholarly communication systems, both as information providers and instructors. However, very little is known regarding their activities as scholars. This study seeks to examine the scholarly communication practices of librarians and archivists, the role that tenure plays in scholarly communication practices, and the degree to which institutional support is provided in librarians’ efforts to consume and disseminate research and reports of best practices. A questionnaire was sent to professional librarians and archivists at 91 ARL institutions. The responses demonstrate that ARL librarians and archivists are avid consumers and creators of scholarship, and they use emerging technologies to stay up-to-date on the profession’s latest research.

Serum heparan sulfate levels are elevated in endotoxemia

BACKGROUND

Increased vascular permeability is a characteristic feature of sepsis which, in the past, has been ascribed exclusively to a malfunction of endothelial cells. However, recently it has become evident that the endothelial glycocalyx is of considerable importance concerning various aspects of vascular physiology, e.g. the vascular barrier and inflammation. Heparan sulfate, one of its essential components is characteristically traceable in blood, in case the endothelial glycocalyx is damaged or destroyed.

METHODS

In 15 pigs we investigated whether the administration of endotoxin from gram-negative bacteria (Escherichia coli) results in increased serum levels of heparan sulfate, signalizing a shedding of the glycocalyx. In addition, markers of inflammation (white blood cell count, platelet count, tumour necrosis factor-α and interleukin-6) were evaluated over an observation period of 6 hours.

RESULTS

Serum heparan sulfate concentrations significantly increased over time in the endotoxin group and were significantly elevated in comparison to the control group 6 hours after administration of endotoxin (p<0.001). In the endotoxin group all markers of inflammation significantly changed during the time course.

CONCLUSIONS

The administration of bacterial endotoxin induced a significant rise in degradation products of the endothelial glycocalyx.

SmgGDS splice variants: Potential novel targets for breast cancer therapeutics

225

Background: Breast cancer malignancy is promoted by the small GTPases K-Ras, Rap1, RhoA, and Rac1. We recently reported that the activity of these GTPases is regulated by two splice variants of SmgGDS, named SmgGDS-558 and SmgGDS-607. SmgGDS is overexpressed in lung and prostate cancer, but its role in breast cancer is unknown. Here we examine whether SmgGDS splice variants are expressed in breast cancer and promote breast cancer malignancy.

Methods: Immunohistochemical staining for SmgGDS was performed on archival human breast tumors (N=183) and normal breast tissue (N=22). Immunoblotting was used to detect SmgGDS splice variants in human breast cancer cell lines. siRNAs that silence different SmgGDS splice variants were used to examine the effects of SmgGDS knockdown on breast cancer cell spreading, cell proliferation via [3H]thymidine uptake, anchorage-independent cell growth using soft agar colony assays, and NF-kB activation using luciferase reporter assays.

Results: SmgGDS expression was detected in >65% of DCIS and invasive lobular and ductal carcinoma, and in 100% of metastatic tumors, but was detected in only 18% of normal breast tissue specimens (p<0.01). All tested cell lines expressed both SmgGDS splice variants. Silencing SmgGDS-558 or SmgGDS-607 with siRNA significantly diminished cell proliferation (100±2.0 vs. 11.3±1.0 vs. 50.5±2.2, p<0.05) in MCF-7 cells, with similar results in MDA-MB-231 and T47D cells. MCF-7 soft agar colony formation was significantly decreased 71% and 49% when SmgGDS-558 or SmgGDS-607 was silenced. MCF-7 cell spreading was promoted by silencing SmgGDS-558, but not SmgGDS-607. NF-kB activation was also decreased by 30% in resting and TNF-α-treated MCF-7 and MDA-MB-231 cells by silencing either splice variant.

Conclusions: SmgGDS is disproportionally expressed in human breast cancers. Reduction of SmgGDS-558 and SmgGDS-607 levels dramatically reduced breast cancer cell proliferation, soft agar colony formation, and NF-kB activation. Our results indicate that SmgGDS splice variants regulate breast cancer malignancy, most likely through their regulation of small GTPases. This study identifies SmgGDS splice variants as novel therapeutic targets in breast cancer.

Interhemispheric correlation of late pleistocene glacial events

A radiocarbon chronology shows that piedmont glacier lobes in the Chilean Andes achieved maxima during the last glaciation at 13,900 to 14,890, 21,000, 23,060, 26,940, 29,600, and >/=33,500 carbon-14 years before present ((14)C yr B.P.) in a cold and wet Subantarctic Parkland environment. The last glaciation ended with massive collapse of ice lobes close to 14,000(14)C yr B.P., accompanied by an influx of North Patagonian Rain Forest species. In the Southern Alps of New Zealand, additional glacial maxima are registered at 17,720(14)C yr B.P., and at the beginning of the Younger Dryas at 11,050 (14)C yr B. P. These glacial maxima in mid-latitude mountains rimming the South Pacific were coeval with ice-rafting pulses in the North Atlantic Ocean. Furthermore, the last termination began suddenly and simultaneously in both polar hemispheres before the resumption of the modern mode of deep-water production in the Nordic Seas. Such interhemispheric coupling implies a global atmospheric signal rather than regional climatic changes caused by North Atlantic thermohaline switches or Laurentide ice surges.

Antibody to aquaporin-4 in the long-term course of neuromyelitis optica

Neuromyelitis optica (NMO) is a severe inflammatory CNS disorder of putative autoimmune aetiology, which predominantly affects the spinal cord and optic nerves. Recently, a highly specific serum reactivity to CNS microvessels, subpia and Virchow-Robin spaces was described in patients with NMO [called NMO-IgG (NMO-immunoglobulin G)]. Subsequently, aquaporin-4 (AQP4), the most abundant water channel in the CNS, was identified as its target antigen. Strong support for a pathogenic role of the antibody would come from studies demonstrating a correlation between AQP4-Ab (AQP4-antibody) titres and the clinical course of disease. In this study, we determined AQP4-Ab serum levels in 96 samples from eight NMO-IgG positive patients (median follow-up 62 months) in a newly developed fluorescence-based immunoprecipitation assay employing recombinant human AQP4. We found that AQP4-Ab serum levels correlate with clinical disease activity, with relapses being preceded by an up to 3-fold increase in AQP4-Ab titres, which was not paralleled by a rise in other serum autoantibodies in one patient. Moreover, AQP4-Ab titres were found to correlate with CD19 cell counts during therapy with rituximab. Treatment with immunosuppressants such as rituximab, azathioprine and cyclophosphamide resulted in a marked reduction in antibody levels and relapse rates. Our results demonstrate a strong relationship between AQP4-Abs and clinical state, and support the hypothesis that these antibodies are involved in the pathogenesis of NMO.

Patient and physician acceptance of a campaign approach to promoting physical activity: the "Move for Health" project

QUESTIONS UNDER STUDY

Physical inactivity increases the risk of many chronic disorders. There is clear evidence that primary care-based interventions to promote physical activity may be effective under controlled research conditions. Yet little is known how this evidence translates into routine primary care practice. The pilot project "Move for Health" tested recruitment of family physicians for a primary prevention project and evaluated the feasibility of systematic assessment and discussion of patients' physical activity taking daily practice routine into account.

METHOD

Patients aged 16-65 years completed a screening questionnaire during 8 two-week campaigns in 2004-5. Physicians evaluated and discussed questionnaire responses and offered a physical activity information leaflet and/or a voucher for a special physical activity counselling session to all inactive patients. Participating practices were interviewed to assess their experience of the project.

RESULTS

40 primary care physicians were motivated to participate. Recruitment was most effective through personal contacts of the project team's colleagues. 67% of the patients completed the screening questionnaire and 92% of these questionnaires were discussed during consultation. 83% of patients accepted the leaflet or the voucher, but only a minority of patients attended the special counselling session. With increasing age and readiness for behavioural change patients were more likely to attend the counselling session.

CONCLUSIONS

A campaign approach consisting of systematic screening and brief counselling of insufficiently active patients in general practice is feasible. Participating practices considered the amount of work associated with the project to be manageable and 1-3 counselling campaigns per year to be feasible if the project runs for several years.

Mechanism of islet amyloid polypeptide fibrillation at lipid interfaces studied by infrared reflection absorption spectroscopy

Islet amyloid polypeptide (IAPP) is a pancreatic hormone and one of a number of proteins that are involved in the formation of amyloid deposits in the islets of Langerhans of type II diabetes mellitus patients. Though IAPP-membrane interactions are known to play a major role in the fibrillation process, the mechanism and the peptide's conformational changes involved are still largely unknown. To obtain new insights into the conformational dynamics of IAPP upon its aggregation at membrane interfaces and to relate these structures to its fibril formation, we studied the association of IAPP at various interfaces including neutral as well as charged phospholipids using infrared reflection absorption spectroscopy. The results obtained reveal that the interaction of human IAPP with the lipid interface is driven by the N-terminal part of the peptide and is largely driven by electrostatic interactions, as the protein is able to associate strongly with negatively charged lipids only. A two-step process is observed upon peptide binding, involving a conformational transition from a largely alpha-helical to a beta-sheet conformation, finally forming ordered fibrillar structures. As revealed by simulations of the infrared reflection absorption spectra and complementary atomic force microscopy studies, the fibrillar structures formed consist of parallel intermolecular beta-sheets lying parallel to the lipid interface but still contain a significant number of turn structures. We may assume that these dynamical conformational changes observed for negatively charged lipid interfaces play an important role as the first steps of IAPP-induced membrane damage in type II diabetes.

Patient and physician acceptance of a campaign approach to promoting physical activity: the "Move for Health" project

QUESTIONS UNDER STUDY

Physical inactivity increases the risk of many chronic disorders. There is clear evidence that primary care-based interventions to promote physical activity may be effective under controlled research conditions. Yet little is known how this evidence translates into routine primary care practice. The pilot project "Move for Health" tested recruitment of family physicians for a primary prevention project and evaluated the feasibility of systematic assessment and discussion of patients' physical activity taking daily practice routine into account.

METHOD

Patients aged 16-65 years completed a screening questionnaire during 8 two-week campaigns in 2004-5. Physicians evaluated and discussed questionnaire responses and offered a physical activity information leaflet and/or a voucher for a special physical activity counselling session to all inactive patients. Participating practices were interviewed to assess their experience of the project.

RESULTS

40 primary care physicians were motivated to participate. Recruitment was most effective through personal contacts of the project team's colleagues. 67% of the patients completed the screening questionnaire and 92% of these questionnaires were discussed during consultation. 83% of patients accepted the leaflet or the voucher, but only a minority of patients attended the special counselling session. With increasing age and readiness for behavioural change patients were more likely to attend the counselling session.

CONCLUSIONS

A campaign approach consisting of systematic screening and brief counselling of insufficiently active patients in general practice is feasible. Participating practices considered the amount of work associated with the project to be manageable and 1-3 counselling campaigns per year to be feasible if the project runs for several years.

[Comparison of different stool tests for the detection of cancer of the colon]

BACKGROUND AND OBJECTIVE

Colonoscopy is the gold standard for the diagnosis of colonic neoplasia. Because of the low compliance, the discomfort of bowel preparation and the procedure itself and the (albeit small) risk of perforation or bleeding alternative procedures such as stool tests are being focused on.

PATIENTS AND METHODS

After informed consent stool samples of 116 patients (44 male, 72 female, median age 47 years), scheduled for colonoscopy and 22 patients (17 m, 5 f, 69 y) with known colorectal cancer stool samples were collected. The samples were investigated by three methods: a biochemical (Guajak) test for fecal occult blood, an immunological test for fecal occult blood and a test determining the dimer pyruvat kinase M2 (tumor M2-PK).

RESULTS

Sensitivity for detection of colorectal cancer or polyps was 27 % and 10 % for the biochemical test, 91 % and 19 % for the immunological test and 77 % and 48 % for the M2-PK-test, respectively. Specificity was 89 %, 94 % and 72 %, respectively.

CONCLUSIONS

Both methods for detection of occult blood had a similar specificity. The sensitivity of the immunological test for the detection of colorectal cancer was significantly higher. The M2-PK-test had a markedly lower specificity in diagnosing cancer. Because of the low sensitivity for polyps the usefulness of stool tests is questionable. Reducing incidence and mortality of colorectal cancer should be achieved by colonoscopy, a recommendation that requires specific communication to the public.

Synthesis and preclinical evaluation of the choline transport tracer deshydroxy-[18F]fluorocholine ([18F]dOC)

11C-labeled choline ([11C]CHO) and 18F-fluorinated choline analogues have been demonstrated to be valuable tracers for in vivo imaging of neoplasms by means of positron emission tomography (PET). The objective of the present study was to evaluate whether deshydroxy-[18F]fluorocholine, ([18F]dOC), a non-metabolizable [18F]fluorinated choline analogue, can serve as a surrogate for cholines that are able to be phosphorylated and thus allow PET-imaging solely by addressing the choline transport system. The specificity of uptake of [18F]dOC was compared with that of [11C]choline ([11C]CHO) in cultured rat pancreatic carcinoma and PC-3 human prostate cancer cells in vitro. In addition, biodistribution of [18F]dOC and [11C]CHO was compared in AR42J- and PC-3 tumor bearing mice. The in vitro studies revealed that membrane transport of both compounds can be inhibited in a concentration dependent manner by similar concentrations of cold choline (IC50 [18F]dOC= 11 microM; IC50 [11C]CHO=13 microM. In vitro studies with PC-3 and AR42J cells revealed that the internalized fraction of [18F]dOC after 5 min incubation time is comparable to that of [11C]CHO, whereas the uptake of [11C]CHO was superior after 20 min incubation time. As for [11C]CHO, kidney and liver were also the primary sites of uptake for [18F]dOC in vivo. Biodistribution data after simultaneous injection of both tracers into AR42J tumor bearing mice revealed slightly higher tumor uptake for [18F]dOC at 10 min post-injection, whereas [11C]CHO uptake was higher at later time points. In conclusion, [18F]dOC is taken up into AR42J rat pancreatic carcinoma and PC-3 human prostate cancer cells by a choline specific transport system. Similar transport rates of [18F]dOC and [11C]CHO result in comparable cellular uptake levels at early time points. In contrast to [18F]dOC, which is transported but not intracellularly trapped, the choline kinase substrate [11C]CHO is transported into tumor cells and retained. Thus, the signal obtained by imaging early after injection is mainly reflecting transport, whereas a valid quantification of choline kinase activity needs imaging at later time points. Further studies have to clarify whether quantification of the transport capacity or the choline kinase activity result in a better pathophysiological correlate and thus is the more useful process for tumor characterization.