CTCF deletion alters the pluripotency and DNA methylation profile of human iPSCs

Pluripotent stem cells are characterized by their differentiation potential toward endoderm, mesoderm, and ectoderm. However, it is still largely unclear how these cell-fate decisions are mediated by epigenetic mechanisms. In this study, we explored the relevance of CCCTC-binding factor (CTCF), a zinc finger-containing DNA-binding protein, which mediates long-range chromatin organization, for directed cell-fate determination. We generated human induced pluripotent stem cell (iPSC) lines with deletions in the protein-coding region in exon 3 of CTCF, resulting in shorter transcripts and overall reduced protein expression. Chromatin immunoprecipitation showed a considerable loss of CTCF binding to target sites. The CTCF deletions resulted in slower growth and modest global changes in gene expression, with downregulation of a subset of pluripotency-associated genes and neuroectodermal genes. CTCF deletion also evoked DNA methylation changes, which were moderately associated with differential gene expression. Notably, CTCF-deletions lead to upregulation of endo-mesodermal associated marker genes and epigenetic signatures, whereas ectodermal differentiation was defective. These results indicate that CTCF plays an important role in the maintenance of pluripotency and differentiation, especially towards ectodermal lineages.

[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.

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.

Proof of principle for the use of 11C-labelled peptides in tumour diagnosis with PET

PURPOSE

The future significance of peptide radiopharmaceuticals in diagnostic imaging with PET will be dependent on methodological aspects, as well as other requirements such as availability of the radionuclide and cost-effectiveness of its production. The aim of this study was to evaluate whether recent improvements in the modification of peptide pharmacokinetics by carbohydration may open a niche for the use of 11C-labelled peptide receptor binding tracers.

METHODS

A carbohydrated analogue of Tyr3-octreotate was used as a clinically relevant peptide. Oxime-mediated coupling between 4-[11C]methoxy-benzaldehyde and an aminooxy-conjugated peptide precursor provided the 11C-labelled peptide in 21+/-5% decay-corrected yield (n=4) in a synthesis time of about 1 h.

RESULTS

In rat pancreas carcinoma xenografted mice, the compound displayed predominant and fast renal clearance combined with high tumour uptake (18.5+/-2.8% ID/g) at 30 min post injection. Corresponding values for kidney, liver and intestine were 18.5+/-2.4% ID/g, 3.2+/-0.5% ID/g and 2.1+/-0.3% ID/g, respectively. In a PET study with xenografted mice, the tumour (0.2-0.3 g) was clearly delineated as early as 20 min after injection. Somatostatin receptor (sstr)-specific uptake was demonstrated by reduction of tumour uptake to 20% of control by co-injection of TOC (0.4 mg/kg; 30 min p.i.).

CONCLUSION

A 11C-labelled octreotate derivative has been prepared which shows suitable pharmacokinetics for in vivo imaging of sstr-overexpressing tumours and thus represents the first proof of principle for the potential of 11C-labelled peptides in tumour imaging.

Inflamed kidneys of NZB / W mice are a major site for the homeostasis of plasma cells

(NZB x NZW)F1 (NZB / W) mice develop a disease similar to human systemic lupus erythematosus (SLE), including autoantibody production, hypergammaglobulinaemia and inflammation of the kidneys. It is known that large numbers of lymphocytes infiltrate the kidneys of these mice. Here, we compare the roles of bone marrow, spleen and inflamed kidneys of NZB / W mice in the activation of B cells and the persistence of antibody-secreting cells (ASC). ASC are present in the kidneys of NZB / W mice with full-blown disease, as many as in the spleen and bone marrow. The specificity of the ASC in the inflamed kidneys is not restricted to self-antigens. After immunization of NZB / W mice with ovalbumin (OVA) the OVA-specific ASC are found initially in the spleen. Weeks later, OVA-specific ASC are found in high numbers in the bone marrow and the kidneys of these mice, but no longer in the spleen. As determined by FACS, B cells with a germinal center phenotype (B220(+) / PNA(+)) are found only in very low numbers in the kidneys, but in high numbers in the spleen of NZB / W mice. Germinal centers could not be detected in the kidneys, but in the spleen, and plasma cells appear to be scattered over the tissue. These data suggest that in autoimmune NZB / W mice, plasma cells generated in immune reactions of secondary lymphoid organs, later accumulate and persist in the inflamed kidneys, were they enhance the local concentrations of Ab and immunocomplexes. These experiments identify the inflamed kidneys of NZB / W mice as a site of prime relevance for the homeostasis of plasma cells, irrespective of their specificity.

Biphasic behavior of the high-spin-->low-spin relaxation of [Fe(btpa)](PF6)2 in solution (btpa = N,N,N',N'-tetrakis(2-pyridylmethyl)-6,6'-bis(aminomethyl)-2,2'- bipyridine)

The light-induced high-spin-->low-spin relaxation for the Fe(II) spin-crossover compounds [Fe(btpa)](PF6)2 and [Fe(b(bdpa))](PF6)2 in solution, where btpa is the potentially octadentate ligand N,N,N',N'-tetrakis(2-pyridylmethyl)-6,6'-bis(aminomethyl)-2,2'-bipyridine and b(bdpa) is the analogous hexadentate ligand N,N'-bis(benzyl)-N,N'-bis(2-pyridylmethyl)-6,6'-bis(aminomethyl)-2,2'- bipyridine, respectively, has been studied by temperature-dependent laser flash photolysis. [Fe(b(bdpa))](PF6)2 shows single-exponential 5T2-->1A1 relaxation kinetics, whereas [Fe(btpa)](PF6)2 exhibits solvent-independent biphasic relaxation kinetics. The fast process of [Fe(btpa)](PF6)2 with a rate constant, kHL, of 2.5 x 10(7) s-1 at 295 K and an activation energy, Ea, of 1294(26) cm-1 in methanol can be assigned to the 5T2-->1A1 relaxation as well. The slow process with a kHL(295 K) of 3.7 x 10(5) s-1 and a Ea of 2297(32) cm-1 in methanol--which is the slowest light-induced relaxation process observed so far for an Fe(II) spin-crossover complex in solution--is assigned to a coupling of the 5T2-->1A1 relaxation process to a geometrical rearrangement within the pendent pyridyl arms.

The arginine finger domain of ExoT contributes to actin cytoskeleton disruption and inhibition of internalization of Pseudomonas aeruginosa by epithelial cells and macrophages

Pseudomonas aeruginosa, an important nosocomial pathogen of humans, expresses a type III secretion system that is required for virulence. Previous studies demonstrated that the lung-virulent strain PA103 has the capacity to be either cytotoxic or invasive. Analyses of mutants suggest that PA103 delivers a negative regulator of invasion, or anti-internalization factor, to host cells via a type III secretion system. In this work we show that the type III secreted protein ExoT inhibits the internalization of PA103 by polarized epithelial cells (Madin-Darby canine kidney cells) and J774.1 macrophage-like cells. ExoS, which is closely related to ExoT but has additional ADP-ribosylating activity, can substitute for ExoT as an anti-internalization factor. ExoT contains a signature arginine finger domain found in GTPase-activating proteins. Mutation of the conserved arginine in ExoT diminished its anti-internalization activity and altered its ability to disrupt the actin cytoskeleton. Cell fractionation experiments showed that ExoT is translocated into host cells and that mutation of the arginine finger did not disrupt translocation. In a mouse model of acute pneumonia, PA103DeltaUDeltaT reached the lungs as efficiently as PA103DeltaU but showed reduced colonization of the liver. This finding suggests that the ability to resist internalization may be important for virulence in vivo.

The tumor necrosis factor-related apoptosis-inducing ligand receptors TRAIL-R1 and TRAIL-R2 have distinct cross-linking requirements for initiation of apoptosis and are non-redundant in JNK activation

Overexpression of the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) receptors, TRAIL-R1 and TRAIL-R2, induces apoptosis and activation of NF-kappaB in cultured cells. In this study, we have demonstrated differential signaling capacities by both receptors using either epitope-tagged soluble TRAIL (sTRAIL) or sTRAIL that was cross-linked with a monoclonal antibody. Interestingly, sTRAIL was sufficient for induction of apoptosis only in cell lines that were killed by agonistic TRAIL-R1- and TRAIL-R2-specific IgG preparations. Moreover, in these cell lines interleukin-6 secretion and NF-kappaB activation were induced by cross-linked or non-cross-linked anti-TRAIL, as well as by both receptor-specific IgGs. However, cross-linking of sTRAIL was required for induction of apoptosis in cell lines that only responded to the agonistic anti-TRAIL-R2-IgG. Interestingly, activation of c-Jun N-terminal kinase (JNK) was only observed in response to either cross-linked sTRAIL or anti-TRAIL-R2-IgG even in cell lines where both receptors were capable of signaling apoptosis and NF-kappaB activation. Taken together, our data suggest that TRAIL-R1 responds to either cross-linked or non-cross-linked sTRAIL which signals NF-kappaB activation and apoptosis, whereas TRAIL-R2 signals NF-kappaB activation, apoptosis, and JNK activation only in response to cross-linked TRAIL.

Detection of BRCA1 and BRCA2 mutations in breast cancer families by a comprehensive two-stage screening procedure

We have developed a 2-stage protocol for BRCA1 and BRCA2 mutation screening from blood spot paper. Stage 1 screening was aimed to analyze patients at highest risk for the most common disease-associated sequence variants listed in the BIC database. Accordingly, stage1 testing implied detection of 18 disease- associated BRCA1 and 9 BRCA2 mutations by adapting the 5' nuclease assay to heterozygote screening. For stage 2 screening, we applied the conformation sensitive gel electrophoresis (CSGE) method by adapting this technique to automated heteroduplex analysis of BRCA1 and BRCA2 using fragment scanning on an ABI 377 sequencing device. Of the 120 patients with a family history of breast and ovarian cancer who took part in this study so far, 45 entered stage 1 testing. Disease-associated mutations were detected in 6 patients by stage 1 testing (13%). For these patients, the final result was available within 10 days. Mutation 300T-->G was found in 2 patients. One patient with mutation 3036delACAA in BRCA2 reported only 1 sister with a multifocal bilateral breast cancer. New disease-associated mutations were detected in 2 of the 114 patients who entered the stage 2 test (1.7%). Of particular interest was 1 patient who was diagnosed with a medullary breast carcinoma at age 39 and who had no family history of breast cancer. We conclude that pre-screening by 5' nuclease assay for the mutations most frequently seen in a given population represents a relatively effective first line of analysis. Subsequent detailed analysis by fluorescence conformation sensitive gel electrophoresis (F-CSGE) and fragment sequencing is a sensitive alternative to full nucleotide sequencing.

[High dosage therapy and autologous peripheral stem cell transplantation in breast carcinoma]

42 breast cancer patients were treated by high-dose chemotherapy (HDC) and autologous peripheral stem-cell transplantation (ASTx) in the Donauspital between 1992 and 1999. 24 patients had stage II/III breast cancer with high risk for relapse. The other 18 patients underwent HDC and ASTx in chemosensitive stage IV. After previous conventional chemotherapy peripheral stem-cells were harvested by one cycle of mobilisation chemotherapy (epirubicin/taxol, FEC 120 or cyclophosphamide) followed by cytokine stimulation. 16 patients were treated by a tandem transplantation (conditioning protocol for 1st ASTx was melphalan 200 mg/m2 and for 2nd transplant it was CTC: cyclophosphamide 6 g/m2; thiotepa 500 mg/m2; carboplatin 800 mg/m2). The other 26 patients received one HDC with CTC as conditioning protocol. The HDC was well tolerated by all patients, there was no transplant-related mortality. The median survival and the progression-free survival (PFS) after HDC and ASTx in stage IV breast cancer patients were 28 and 11 months, respectively. The median survival and PFS were not yet reached in stage II/III patients after 55 months. The actuarial survival and PFS in that patient group were 70% after 55 months. Our data confirm the low risk and good efficacy of HDC and ASTx in breast cancer patients. Nevertheless randomised studies are necessary to evaluate the importance of HDC compared to intensified conventional protocols without ASTx.

A thermal spin transition in [Co(bpy)3][LiCr(ox)3] (ox = C2O4(2-); bpy = 2,2'-bipyridine)

In the three-dimensional oxalate network structures [M(II)(bpy)3][M(I)-M(III)(ox)3] (ox= C2O4(2-); bpy = 2,2'-bipyridine) the negatively charged oxalate backbone provides perfect cavities for tris-bipyridyl complex cations. The size of the cavity can be adjusted by variation of the metal ions of the oxalate backbone. In [Co(bpy)3][NaCr(ox)3], the [Co(bpy)3]2 + complex is in its usual 4T1(t2g5e(g)2) high-spin ground state. Substituting Na+ by Li+ reduces the size of the cavity. The resulting chemical pressure destabilises the high-spin state of [Co(bpy)3]2+ to such an extent that the 2E(t2g6e(g)1) low-spin state becomes the actual ground state. As a result. [Co(bpy)3][LiCr(ox)3] becomes a spin-crossover system, as shown by temperature-dependent magnetic susceptibility measurements and single-crystal optical spectroscopy, as well as by an X-ray structure determination at 290 and 10 K.