Combined absence of TRP53 target genes ZMAT3, PUMA and p21 cause a high incidence of cancer in mice

Transcriptional activation of target genes is essential for TP53-mediated tumour suppression, though the roles of the diverse TP53-activated target genes in tumour suppression remains poorly understood. Knockdown of ZMAT3, an RNA-binding zinc-finger protein involved in regulating alternative splicing, in haematopoietic cells by shRNA caused leukaemia only with the concomitant absence of the PUMA and p21, the critical effectors of TRP53-mediated apoptosis and cell cycle arrest respectively. We were interested to further investigate the role of ZMAT3 in tumour suppression beyond the haematopoietic system. Therefore, we generated Zmat3 knockout and compound gene knockout mice, lacking Zmat3 and p21, Zmat3 and Puma or all three genes. Puma-/-p21-/-Zmat3-/- triple knockout mice developed tumours at a significantly higher frequency compared to wild-type, Puma-/-Zmat3-/- or p21-/-Zmat3-/-deficient mice. Interestingly, we observed that the triple knockout and Puma-/-Zmat3-/- double deficient animals succumbed to lymphoma, while p21-/-Zmat3-/- animals developed mainly solid cancers. This analysis suggests that in addition to ZMAT3 loss, additional TRP53-regulated processes must be disabled simultaneously for TRP53-mediated tumour suppression to fail. Our findings reveal that the absence of different TRP53 regulated tumour suppressive processes changes the tumour spectrum, indicating that different TRP53 tumour suppressive pathways are more critical in different tissues.

XIAP promotes melanoma growth by inducing tumour neutrophil infiltration

Elevated expression of the X‐linked inhibitor of apoptosis protein (XIAP) has been frequently reported in malignant melanoma suggesting that XIAP renders apoptosis resistance and thereby supports melanoma progression. Independent of its anti‐apoptotic function, XIAP mediates cellular inflammatory signalling and promotes immunity against bacterial infection. The pro‐inflammatory function of XIAP has not yet been considered in cancer. By providing detailed in vitro analyses, utilising two independent mouse melanoma models and including human melanoma samples, we show here that XIAP is an important mediator of melanoma neutrophil infiltration. Neutrophils represent a major driver of melanoma progression and are increasingly considered as a valuable therapeutic target in solid cancer. Our data reveal that XIAP ubiquitylates RIPK2, involve TAB1/RIPK2 complex and induce the transcriptional up‐regulation and secretion of chemokines such as IL8, that are responsible for intra‐tumour neutrophil accumulation. Alteration of the XIAP‐RIPK2‐TAB1 inflammatory axis or the depletion of neutrophils in mice reduced melanoma growth. Our data shed new light on how XIAP contributes to tumour growth and provides important insights for novel XIAP targeting strategies in cancer.

Explicit achievement motive strength determines effort-related myocardial beta-adrenergic activity if task difficulty is unclear but not if task difficulty is clear

Work on physiological and other behavioral correlates of motives often assumes that motives exert a direct effect on behavior once activated. Motivational intensity theory, however, suggests that this does not always apply. In the context of task engagement, motive strength should exert a direct effect on myocardial beta-adrenergic activity if task difficulty is unclear, but not if task difficulty is known. The presented study tested this prediction for the impact of the explicit achievement motive on myocardial beta-adrenergic activity-assessed as pre-ejection period (PEP) reactivity during task performance. Seventy-eight participants performed one of two versions of a mental arithmetic task. After having completed the achievement motive scale of the Personality Research Form, participants were either informed about the difficulty of the task or not before working on it. Participants' PEP reactivity during task performance provided evidence for the predicted moderating impact of clarity of task difficulty: PEP reactivity increased with increasing achievement motive strength if task difficulty was unclear, but not if it was clear. These findings demonstrate that the explicit achievement motive impact on myocardial beta-adrenergic activity is moderated by clarity of task difficulty and suggest that motive strength does not always translate into direct effects on physiology and behavior.

The Intensity Side of Volition

Abstract. Attaining sports or health goals requires not only high motivation but also the willpower to translate sport-behavior intentions into successful action. This volitional regulation calls for the mobilization of effort to overcome obstacles in the pursuit of goals. The present article provides a theoretical and empirical overview of motivation intensity theory ( Brehm & Self, 1989 ) – a conceptual framework that makes clear and testable predictions about effort mobilization in various contexts. First, we present the guiding principles of this theory and its operationalizations by measures of effort-related cardiovascular reactivity and physical handgrip force. Second, we review a selection of empirical tests of the basic assumptions of this theory and the impact of psychological moderator variables such as affect, fatigue, pain, and personality on effort mobilization. Finally, we discuss important implications of these findings for the sports and health domains and make suggestions for future research.

Clarity of task difficulty moderates the impact of the explicit achievement motive on physical effort in hand grip tasks

Stable personality dispositions, like motives, are often assumed to exert a direct, stable impact on behavior. This also applies to the explicit achievement motive, which is supposed to influence the behavior that individuals select and how strongly they engage in it. Drawing on motivational intensity theory, we demonstrated in two studies that explicit achievement motive strength only predicted exerted force in a hand grip task if task difficulty was unclear. If task difficulty was clear, explicit achievement motive strength did not influence exerted force. Our findings suggest that the availability of information about the difficulty of motive satisfaction moderates the impact of the explicit achievement motive on behavior.

BCL-XL exerts a protective role against anemia caused by radiation-induced kidney damage

Studies of gene-targeted mice identified the roles of the different pro-survival BCL-2 proteins during embryogenesis. However, little is known about the role(s) of these proteins in adults in response to cytotoxic stresses, such as treatment with anti-cancer agents. We investigated the role of BCL-XL in adult mice using a strategy where prior bone marrow transplantation allowed for loss of BCL-XL exclusively in non-hematopoietic tissues to prevent anemia caused by BCL-XL deficiency in erythroid cells. Unexpectedly, the combination of total body γ-irradiation (TBI) and genetic loss of Bcl-x caused secondary anemia resulting from chronic renal failure due to apoptosis of renal tubular epithelium with secondary obstructive nephropathy. These findings identify a critical protective role of BCL-XL in the adult kidney and inform on the use of BCL-XL inhibitors in combination with DNA damage-inducing drugs for cancer therapy. Encouragingly, the combination of DNA damage-inducing anti-cancer therapy plus a BCL-XL inhibitor could be tolerated in mice, at least when applied sequentially.

When Should I Stop? Dysphoria Leads to Impaired Task Persistence via Negative Mood

Abstract. Based on reported motivational deficits in depression – and on persistence deficits in particular – the present study examined whether dysphoric individuals benefit from task contexts that favor longer task persistence. Undergraduates worked on an item-generation task with different stop rules: “Is this a good time to stop?” ( enough rule), “Do I feel like continuing?” ( enjoy rule), or no specific rule. Results revealed that, independent of the stop rule, participants with high depression scores stopped earlier and generated fewer items than participants with low depression scores – an effect that was mediated by current mood state. Thus, contrary to experimentally induced negative mood, the enough-rule intervention was ineffective in eliminating the persistence deficits of dysphoric individuals. Implications for task disengagement and performance outcomes are discussed.

miR17~92 restrains pro-apoptotic BIM to ensure survival of haematopoietic stem and progenitor cells

The miR17~92 cluster plays important roles in haematopoiesis. However, it is not clear at what stage of differentiation and through which targets miR17~92 exerts this function. Therefore, we generated miR17~92^fl/fl; RosaCreERT2 mice for inducible deletion of miR17~92 in haematopoietic cells. Bone marrow reconstitution experiments revealed that miR17~92-deleted cells were not capable to contribute to mature haematopoietic lineages, which was due to defects in haematopoietic stem/progenitor cells (HSPCs). To identify the critical factor targeted by miR17~92 we performed gene expression analysis in HSPCs, demonstrating that mRNA levels of pro-apoptotic Bim inversely correlated with the expression of the miR17~92 cluster. Strikingly, loss of pro-apoptotic BIM completely prevented the loss of HSPCs caused by deletion of miR17~92. The BIM/miR17~92 interaction is conserved in human CD34⁺ HSPCs, as miR17~92 inhibition or blockade of its binding to the BIM 3'UTR reduced the survival and growth of these cells. Despite the prediction that miR17~92 functions by impacting a plethora of different targets, the absence of BIM alone is sufficient to prevent all defects caused by deletion of miR17~92 in haematopoietic cells.

Characterisation of mice lacking the inflammatory caspases-1/11/12 reveals no contribution of caspase-12 to cell death and sepsis

Caspases exert critical functions in diverse cell death pathways, including apoptosis and pyroptosis, but some caspases also have roles in the processing of cytokines into their functional forms during inflammation. The roles of many caspases have been unravelled by the generation of knockout mice, but still very little is known about the overlapping functions of caspases as only a few studies report on double or triple caspase knockout mice. For example, the functions of caspase-12 in cell death and inflammation, on its own or overlapping with the functions of caspase-1 and caspase-11, are only poorly understood. Therefore, we generated a novel mutant mouse strain lacking all three inflammatory caspases, caspases-1, -11 and -12. Analysis under steady state conditions showed no obvious differences between caspase-1/11/12-/- and wildtype (WT) mice. Since caspases-1 and -11 are involved in endotoxic shock, we analysed the response of caspase-1/11/12-/- mice to high-dose LPS injection. Interestingly, we could not detect any differences in responses between caspase-1/11/12-/- mice vs. caspase-1/11 double knockout mice. Furthermore, cell lines generated from caspase-1/11/12-/- mice showed no differences in their apoptotic or necroptotic responses to a diverse set of cytotoxic drugs in vitro when compared to WT cells. Importantly, these drugs also included ER stress-inducing agents, such as thapsigargin and tunicamycin, a form of cell death for which a critical pro-apoptotic function of caspase-12 has previously been reported. Additionally, we found no differences between caspase-1/11/12-/- and WT mice in their in vivo responses to the ER stress-inducing agent, tunicamycin. Collectively, these findings reveal that caspase-12 does not have readily recognisable overlapping roles with caspases-1 and -11 in the inflammatory response induced by LPS and in necroptosis and apoptosis induced by diverse cytotoxic agents, including the ones that elicit ER stress.

Major depression impairs incentive processing: evidence from the heart and the face

BACKGROUND

The present study tested the hypothesis of a differential pattern of reward and punishment responsiveness in depression measuring effort mobilization during anticipation and facial expressions during consumption.

METHODS

Twenty patients with major depressive disorder (MDD) and 20 control participants worked on a memory task under neutral, reward, and punishment instructions. Effort mobilization was operationalized as cardiovascular reactivity, while facial expressions were measured by facial electromyographic reactivity. Self-report measures for each phase complemented this multi-method approach.

RESULTS

During anticipation, MDD patients showed weaker cardiac pre-ejection period (PEP) reactivity to reward and blunted self-reported wanting, but weaker PEP reactivity to punishment and unchanged self-reported avoidance motivation. During consumption, MDD patients showed reduced zygomaticus major muscle reactivity to reward and blunted self-reported liking, but unchanged corrugator supercilii muscle reactivity to punishment and unchanged self-reported disliking.

CONCLUSIONS

These findings demonstrate reduced effort mobilization during reward and punishment anticipation in depression. Moreover, they show reduced facial expressions during reward consumption and unchanged facial expressions during punishment consumption in depression.

Improved EGFR mutation detection using combined exosomal RNA and circulating tumor DNA in NSCLC patient plasma

Background

A major limitation of circulating tumor DNA (ctDNA) for somatic mutation detection has been the low level of ctDNA found in a subset of cancer patients. We investigated whether using a combined isolation of exosomal RNA (exoRNA) and cell-free DNA (cfDNA) could improve blood-based liquid biopsy for EGFR mutation detection in non-small-cell lung cancer (NSCLC) patients.

Patients and methods

Matched pretreatment tumor and plasma were collected from 84 patients enrolled in TIGER-X (NCT01526928), a phase 1/2 study of rociletinib in mutant EGFR NSCLC patients. The combined isolated exoRNA and cfDNA (exoNA) was analyzed blinded for mutations using a targeted next-generation sequencing panel (EXO1000) and compared with existing data from the same samples using analysis of ctDNA by BEAMing.

Results

For exoNA, the sensitivity was 98% for detection of activating EGFR mutations and 90% for EGFR T790M. The corresponding sensitivities for ctDNA by BEAMing were 82% for activating mutations and 84% for T790M. In a subgroup of patients with intrathoracic metastatic disease (M0/M1a; n = 21), the sensitivity increased from 26% to 74% for activating mutations (P = 0.003) and from 19% to 31% for T790M (P = 0.5) when using exoNA for detection.

Conclusions

Combining exoRNA and ctDNA increased the sensitivity for EGFR mutation detection in plasma, with the largest improvement seen in the subgroup of M0/M1a disease patients known to have low levels of ctDNA and poses challenges for mutation detection on ctDNA alone.

Clinical Trials

NCT01526928.

IAP antagonization promotes inflammatory destruction of vascular endothelium

In this study, we show for the first time that the therapeutic antagonization of inhibitor of apoptosis proteins (IAPs) inhibits B16 melanoma growth by disrupting tumor vasculature. Specifically, the treatment of mice bearing B16 melanoma with an IAP antagonist compound A (Comp A) inhibits tumor growth not by inducing direct cytotoxicity against B16 cells but rather by a hitherto unrecognized antiangiogenic activity against tumor vessels. Our detailed analysis showed that Comp A treatment induces NF-κB activity in B16 tumor cells and facilitates the production of TNF. In the presence of Comp A, endothelial cells (ECs) become highly susceptible to TNF and undergo apoptotic cell death. Accordingly, the antiangiogenic and growth-attenuating effects of Comp A treatment were completely abolished in TNF-R knockout mice. This novel targeting approach could be of clinical value in controlling pathological neoangiogenesis under inflammatory condition while sparing blood vessels under normal condition.

Regulation of the DNA damage response by ubiquitin conjugation

In response to DNA damage, cells activate a highly conserved and complex kinase-based signaling network, commonly referred to as the DNA damage response (DDR), to safeguard genomic integrity. The DDR consists of a set of tightly regulated events, including detection of DNA damage, accumulation of DNA repair factors at the site of damage, and finally physical repair of the lesion. Upon overwhelming damage the DDR provokes detrimental cellular actions by involving the apoptotic machinery and inducing a coordinated demise of the damaged cells (DNA damage-induced apoptosis, DDIA). These diverse actions involve transcriptional activation of several genes that govern the DDR. Moreover, recent observations highlighted the role of ubiquitylation in orchestrating the DDR, providing a dynamic cellular regulatory circuit helping to guarantee genomic stability and cellular homeostasis (Popovic et al., 2014). One of the hallmarks of human cancer is genomic instability (Hanahan and Weinberg, 2011). Not surprisingly, deregulation of the DDR can lead to human diseases, including cancer, and can induce resistance to genotoxic anti-cancer therapy (Lord and Ashworth, 2012). Here, we summarize the role of ubiquitin-signaling in the DDR with special emphasis on its role in cancer and highlight the therapeutic value of the ubiquitin-conjugation machinery as a target in anti-cancer treatment strategy.

Embelin inhibits endothelial mitochondrial respiration and impairs neoangiogenesis during tumor growth and wound healing

In the normal quiescent vasculature, only 0.01% of endothelial cells (ECs) are proliferating. However, this proportion increases dramatically following the angiogenic switch during tumor growth or wound healing. Recent evidence suggests that this angiogenic switch is accompanied by a metabolic switch. Here, we show that proliferating ECs increasingly depend on mitochondrial oxidative phosphorylation (OxPhos) for their increased energy demand. Under growth conditions, ECs consume three times more oxygen than quiescent ECs and work close to their respiratory limit. The increased utilization of the proton motif force leads to a reduced mitochondrial membrane potential in proliferating ECs and sensitizes to mitochondrial uncoupling. The benzoquinone embelin is a weak mitochondrial uncoupler that prevents neoangiogenesis during tumor growth and wound healing by exhausting the low respiratory reserve of proliferating ECs without adversely affecting quiescent ECs. We demonstrate that this can be exploited therapeutically by attenuating tumor growth in syngenic and xenograft mouse models. This novel metabolic targeting approach might be clinically valuable in controlling pathological neoangiogenesis while sparing normal vasculature and complementing cytostatic drugs in cancer treatment.

Noxa and cancer therapy: Tuning up the mitochondrial death machinery in response to chemotherapy

Biochemical analyses have characterized the BH3-only protein family member Noxa as a “sensitizer” with weak pro-apoptotic activity. Investigations into cancer cell responses to chemotherapeutic agents have identified Noxa as a pivotal factor mediating the cytotoxic effect of a plethora of anticancer treatments independent of its own pro-apoptotic activity. Accumulating evidence now suggests that tumor cells exert a number of strategies to counteract Noxa function by exploiting diverse cellular regulatory circuits that normally govern Noxa expression during cellular stress responses. Here, we summarize data concerning the role of Noxa in cancer chemosensitivity and highlight the potential of this enigmatic BH3-only protein family member in current and novel anticancer therapies.

BID-dependent release of mitochondrial SMAC dampens XIAP-mediated immunity against Shigella

The X-linked inhibitor of apoptosis protein (XIAP) is a potent caspase inhibitor, best known for its anti-apoptotic function in cancer. During apoptosis, XIAP is antagonized by SMAC, which is released from the mitochondria upon caspase-mediated activation of BID. Recent studies suggest that XIAP is involved in immune signaling. Here, we explore XIAP as an important mediator of an immune response against the enteroinvasive bacterium Shigella flexneri, both in vitro and in vivo. Our data demonstrate for the first time that Shigella evades the XIAP-mediated immune response by inducing the BID-dependent release of SMAC from the mitochondria. Unlike apoptotic stimuli, Shigella activates the calpain-dependent cleavage of BID to trigger the release of SMAC, which antagonizes the inflammatory action of XIAP without inducing apoptosis. Our results demonstrate how the cellular death machinery can be subverted by an invasive pathogen to ensure bacterial colonization.

System Analysis of the Circadian Rhythm of Euglena gracilis, II: Masking Effects and Mutual Interactions of Light and Temperature Responses

Motility of Euglena gracilis shows free running circadian rhythms. The circadian system is sensitive to light and temperature signals, but it is always masked by direct responses of motility to light (photokinesis) and temperature (thermokinesis). By means of a compartimental model which defines the interrelations between the pathways of thermokinesis, photokinesis and the circadian system a unifying view of effects of temperature and light input signals is outlined. According to the model, and using double sine input signals the dynamics of thermokinesis is described by a differential amplifier with constant gain.

Although thermokinesis heavily masks circadian responses to temperature signals, the limited range of circadian entrainment is indirectly demonstrated by a limited reappearance of free running circadian oscillations after stopping the temperature program. Free running circadian oscillations do reappear only after pretreatment with temperature periods near the circadian eigenperiod.

A white mutant lacking photosynthesis is used to investigate the role of photosynthesis in the signal processing. Although light synchronizes the circadian rhythms of the white mutant if applied as single input, it does not affect the motility if applied together with temperature inputs near the circadian eigenperiod. These results indicate frequency dependent mutual interactions between the model compartments.

Second mitochondria-derived activator of caspase (SMAC) mimetic potentiates tumor susceptibility toward natural killer cell-mediated killing

Resistance to apoptosis is a hallmark of cancer, and represents an important mechanism of how tumor cells resist immune cell destruction. Mitochondria are the central regulators of the apoptotic machinery by releasing pro-apoptotic factors including cytochrome c and second mitochondria-derived activator of caspase (SMAC) upon mitochondrial outer membrane permeabilization (MOMP). Small molecules activating MOMP such as BH3 mimetics or antagonizers of the inhibitor of apoptosis proteins (IAPs) such as SMAC mimetics have recently engendered new optimism for a more individualized and effective cancer therapy. Here we show that a SMAC mimetic potentiates cancer cell killing by natural killer (NK) cells through reactivation of tumor cell apoptosis. Specifically, the SMAC mimetic enhances the susceptibility of tumor cells toward NK cell-mediated effector mechanisms involving death receptors and cytolytic granules containing perforin and granzymes by relieving caspase activity. Our data highlight for the first time the specific use of SMAC mimetics for boosting immune cell-mediated immunotherapy, representing a novel and promising approach in the treatment of cancer.

Anatomy of the White Bear Suppression Inventory (WBSI): a review of previous findings and a new approach

The White Bear Suppression Inventory (WBSI; Wegner & Zanakos, 1994) was originally designed to assess people's inclination toward thought suppression. In this article, we provide a detailed review of previous findings on the structure of this instrument and present a study that took a new statistical approach. It involved an exploratory factor analysis of the French WBSI using the weighted least squares mean and variance estimator as well as parametric item response theory analyses. Results clearly supported a 2-factor structure with a "suppression" and an "intrusion" dimension. Follow-up regression analyses revealed that intrusion significantly predicted anxiety and depression scores, whereas suppression did not.

The proteasome inhibitor bortezomib sensitizes melanoma cells toward adoptive CTL attack

Adoptive transfer of tumor-specific cytolytic T lymphocytes (CTL) results in target cell lysis by activating the intrinsic apoptotic cell death program. Not surprisingly, deregulation of the apoptotic machinery is one of the central mechanisms by which tumor cells escape immune destruction despite specific CTL recognition. Here we show that treatment with the proteasome inhibitor bortezomib sensitizes previously resistant tumor cells for cytolytic T-cell attack. Human T cells were redirected toward melanoma cells by engineered expression of an immunoreceptor with binding specificity for high molecular weight-melanoma-associated antigen. Established melanoma cell lines as well as primary melanoma cells from tumor biopsies, which are notoriously resistant toward T-cell lysis, became sensitive upon bortezomib treatment. Detailed analysis of the underlying molecular mechanism revealed that bortezomib treatment induced mitochondrial accumulation of NOXA, which potentiated the release of mitochondrial second mitochondria-derived activator of caspase (SMAC) in response to CTL effector functions, including caspase-8 and granzyme B. Our data indicate that proteasome inhibition increases the sensitivity of tumor cells toward cytolytic T-cell attack by NOXA-mediated enhancement of mitochondrial SMAC release.

Anhedonia and effort mobilization in dysphoria: reduced cardiovascular response to reward and punishment

Instigated by evidence for reduced responsiveness to reward in depression, the present two studies addressed the question if such anhedonic behavior would also become evident in reduced mobilization of mental effort in terms of cardiovascular reactivity. Undergraduates completed the Center for Epidemiologic Studies-Depression Scale (CES-D) and worked on mental tasks, expecting either no consequence, a performance-contingent reward, or a performance-contingent punishment. Study 1 revealed that participants with low CES-D scores showed high systolic blood pressure reactivity in the punishment condition, whereas participants with high CES-D scores showed low systolic reactivity. Study 2 corroborated this finding for reward: Nondysphoric participants expecting a reward showed higher reactivity of systolic blood pressure and pre-ejection period than participants in the neutral condition or than dysphoric participants. Together, the studies demonstrate that reward insensitivity in (subclinical) depression is also found in cardiovascular reactivity. Furthermore, dysphoric individuals do not respond to punishment either, suggesting a general insensitivity to hedonic consequences.

Does depression interfere with effort mobilization? Effects of dysphoria and task difficulty on cardiovascular response

On the basis of predictions of the mood-behavior model (G. H. E. Gendolla, 2000) and motivational intensity theory (J. W. Brehm & E. A. Self, 1989), the authors conducted 2 studies that critically tested the common assumption that dysphoria is associated with a motivational deficit. Dysphoric and nondysphoric undergraduates performed a cognitive task that was either easy or difficult. Effort intensity (i.e., resource mobilization) was assessed as performance-related cardiovascular reactivity. In support of the authors' predictions and in contrast to the popular view of a general motivational deficit, both studies found a crossover interaction between dysphoria and task difficulty: In the difficult condition, nondysphoric participants indeed showed stronger systolic blood pressure reactivity than dysphoric participants. But in the easy condition, dysphoric participants showed stronger systolic reactivity than nondysphoric participants. The findings are discussed with respect to motivational deficits in depression and possible underlying mechanisms.

The Role of Mood States in Self-Regulation

Abstract. Based on the mood-behavior-model (MBM; Gendolla, 2000 ), it is proposed that moods play significant roles in two central processes of self-regulation: (1) The constitution of action preferences and (2) resource mobilization in instrumental behavior. Specifically, people's interest in behaviors that facilitate hedonic experiences depends on their momentary need for well-being and the perceived instrumentality of potential acts for satisfying this need. Resource mobilization is influenced by the use of moods as diagnostic information for demand appraisals, which in turn determine the intensity of effort and the persistence of behavior. A series of experiments that quantified effort as cardiovascular response has supported these predictions. The role of personality variables in the linkage between mood states and self-regulation is discussed.

European Society of Cardiology--XXIII congress. New and established therapies

The annual European Society of Cardiology XXIII Congress was an internationally represented meeting, focusing on the latest developments in cardiac pharmaceutical research and clinical applications. Poster and oral presentations displayed the importance of clinical trials for safety and efficacy of current drugs mainly acting on blocking of signaling pathways in the hyperactivated failing heart or prevention and reversion of vessel occlusions. Additionally, several new drug classes were introduced and tested in small-scale studies. In addition to improved surgical methods discussed at the congress, new classes of minimally invasive treatments were reported, including gene therapy and cell transplantation techniques which could provide additional future cure for cardiac patients.

Residential magnetic fields as a risk factor for childhood acute leukaemia: results from a German population-based case-control study

Our objective was to investigate whether exposure to residential power-frequency (50 Hz) magnetic fields above 0.2 microT increases a child's risk of leukaemia and to confirm or reject a finding from a previous German study on this topic, which reported increased leukaemia risk with exposure to stronger magnetic fields during the night. A population-based case-control study was used, covering the whole of the former West Germany. Residential magnetic fields were measured over 24 hr for 514 children with acute leukaemia identified by the German Childhood Cancer Registry and 1,301 control children taken from population registration files. Magnetic fields above 0.2 microT were relatively rare in Germany (only 1.5% of the study population). Childhood leukaemia and 24 hr median magnetic fields were only weakly related (OR = 1.55, 95% CI 0.65-3.67). A significant association was seen between childhood leukaemia and magnetic field exposure during the night (OR = 3.21, 95% CI 1.33-7.80). A dose-response-relationship was observed after combining the data of all German studies on magnetic fields and childhood leukaemia. The evidence for an association between childhood leukaemia and magnetic field exposure in our study comes from a measure of exposure during the night. Despite the large size of our study, the results are based on small numbers of exposed children. If the observed association stands, the effect on a population level in Germany would be small.

Childhood acute leukaemia and residential 16.7 Hz magnetic fields in Germany

We observed a moderate but statistically non-significant association between magnetic fields (MF) and childhood leukaemia. This is the first such study to cover residential exposure to 16.7 Hz (railway frequency) MF though based on few exposed subjects. Our study does not exclude a small excess risk, but the attributable risk must be very low. It is reassuring that neglecting 16.7 Hz MF in childhood cancer studies appears to have little effect on findings.

Extremely low frequency magnetic fields in residences in Germany. Distribution of measurements, comparison of two methods for assessing exposure, and predictors for the occurrence of magnetic fields above background level

We examined the results of 1,835 magnetic field measurements in German residences conducted between November 1997 and September 1999. The measurements were part of an epidemiological study on the relationship between magnetic fields and childhood leukemia. We performed a fixed-location measurement of the magnetic field at 50 Hz and 16 2/3 Hz (frequency of the German railway system) over 24 h in the child's bedroom in the residence of each study participant. In addition, we conducted a second 24 h-measurement in the living room at 50 Hz, and spot measurements while walking through all rooms of the respective dwelling. Median 50 Hz magnetic fields above 0.2 muT were found to be infrequent in Germany (only 1.4% of all residences). Fields produced by high-voltage power lines (123-420 kV) were lower than expected: the median magnetic field was above 0.2 muT in only 8 (32.0%) of 25 residences located 50 m or closer to a high-voltage power line indicating that power lines in Germany are usually run well below the maximum power load. We found that magnetic fields were correlated with the type of residence and higher magnetic fields were measured in apartment buildings. There was also some evidence for a positive correlation between magnetic fields and traffic density and an inverse association between magnetic fields and family net income. The 24 h-magnetic field measurements correlated well with the spot measurements (r>0.7). However, when dichotomized with a cut-off point of 0.2 muT, there was only a poor agreement between the two measurement methods. A loss of the strength of the association after categorization was also observed when comparing the arithmetic mean and median of the same 24 h-measurement. In summary, these analyses give a valuable overview of magnetic field distributions in German residences.

Mitochondrial DNA in human hair shafts--existence of intra-individual differences?

The sequences of the hypervariable region 1 (HV1) of the mitochondrial DNA control region from multiple hair shafts from 10 unrelated individuals were compared to determine the frequency of differences in hairs from one individual. The extraction method described herein showed an average success rate of 67% for all 150 hair shafts tested in HV1. The mtDNA sequences from the hair shafts matched the sequences from the corresponding blood and saliva samples taken from the same donor and no evidence of heteroplasmy was found. The results emphasize the reliability of DNA extraction and mtDNA typing from human hair shafts for forensic purposes.

Combined risk estimates for two German population-based case-control studies on residential magnetic fields and childhood acute leukemia

From 1992 to 1996, we obtained electromagnetic field measurements in two population-based case-control studies on childhood leukemia in the northwestern part of Germany and in Berlin. Exposure assessment comprised residential 24-hour measurements and short-term measurements. We obtained 24-hour measurements for a total of 176 cases and 414 controls. We compared subjects exposed to median 24-hour measurements of 0.2 microT or more with those exposed to lower amounts. Multivariate regression analysis revealed an odds ratio of 2.3 (95% confidence interval = 0.8-6.7).

Fluoresceinyl-ethylenediamine-ouabain detects an acidic environment in the cardiac glycoside binding site of Na+/K+-ATPase

To probe the pH value in the microenvironment of the cardiac glycoside-binding site of Na+/K+-ATPase, pH-sensitive fluorescent derivatives of ouabain were synthesized. The fluoresceinyl derivative of ethylenediamino-ouabain (FEDO) had a pKs of 6.0 and showed a H+-dependent fluorescence change, when its ratio of excitation at 490 nm/450 nm was recorded at 530 nm. Binding of FEDO inactivated Na+/K+-ATPase at 37 degrees C and pH 7.25 in a slow time-dependent process under the conditions of backdoor phosphorylation with k(on) of 891 s(-1) M(-1). The complex dissociated with k(on) of 0.35 x 10(-3) s(-1) resulting in a Kd value of 0.4 microM for the FEDO x enzyme complex. Binding of FEDO was associated with a decrease of the excitatory fluorescence ratio at 490 nm/450 nm which could be used to convert this change into a pH value. A pH value of 5.1 +/- 0.2 was calculated to exist in the microenvironment of the FEDO x enzyme complex. This pH value was independent of the pH of the incubation medium used to form the FEDO x enzyme complex. Analysis of the accessibility of the fluorophore in the FEDO x enzyme complex to the dynamic quencher potassium iodide detected a decrease of the Stern-Volmer constant from 6.2 mM(-1) (free FEDO) to 1.5 mM(-1) (FEDO x enzyme complex) indicating thereby a limited accessibility of the fluorophore to anions. Analysis of the microenvironment of the fluorescein residue of the FEDO x enzyme complex by measurements of the anisotropy and the fluorescence half-life time revealed that both processes differed significantly when H2O was replaced by D2O. We conclude, therefore, that a pH of 5.1 +/- 0.2 exists in the vicinity of ouabain that is hidden in the depth of the receptor site when the ouabain receptor complex has been formed.

Childhood leukemia and electromagnetic fields: results of a population-based case-control study in Germany

The investigation of an association between increased exposure to residential extremely-low frequency electromagnetic fields (ELF-EMF) and childhood leukemia was part of a population-based case-control study carried out between 1992 and 1995 in the northwestern part of Germany. A total of 129 children with leukemia and 328 controls participated in the EMF-study. Exposure assessment comprised measurements of the magnetic field over 24 hours in the child's bedroom at the residence where the child had been living for the longest period before the date of diagnosis, and spot measurements at all residences where the child had been living for more than one year. The median of the 24h-measurement in the child's bedroom was regarded as the most valid exposure variable. For children exposed to more than 0.2 microT, an elevated but not significant odds ratio (OR) was observed (OR = 3.2, 95 percent confidence interval = 0.7-14.9). These figures are based on only four leukemia cases and three controls since only 1.5 percent of the study population was classified as highly exposed. Exploratory analyses revealed ORs that were not statistically significantly increased for other characteristics of the magnetic field at varying cut-points. The results are comparable with those from other studies. Although not statistically significant, they may indicate a positive association between EMF and childhood leukemia.