Differential forms on Carnot groups

The main goal of this thesis is to understand and link together some of the early works by Michel Rumin and Pierre Julg. The work is centered around the so-called Rumin complex, which is a construction in subRiemannian geometry. A Carnot manifold is a manifold endowed with a horizontal distribution. If further a metric is given, one gets a subRiemannian manifold. Such data arise in different contexts, such as: - formulation of the second principle of thermodynamics; - optimal control; - propagation of singularities for sums of squares of vector fields; - real hypersurfaces in complex manifolds; - ideal boundaries of rank one symmetric spaces; - asymptotic geometry of nilpotent groups; - modelization of human vision. Differential forms on a Carnot manifold have weights, which produces a filtered complex. In view of applications to nilpotent groups, Rumin has defined a substitute for the de Rham complex, adapted to this filtration. The presence of a filtered complex also suggests the use of the formal machinery of spectral sequences in the study of cohomology. The goal was indeed to understand the link between Rumin's operator and the differentials which appear in the various spectral sequences we have worked with: - the weight spectral sequence; - a special spectral sequence introduced by Julg and called by him Forman's spectral sequence; - Forman's spectral sequence (which turns out to be unrelated to the previous one). We will see that in general Rumin's operator depends on choices. However, in some special cases, it does not because it has an alternative interpretation as a differential in a natural spectral sequence. After defining Carnot groups and analysing their main properties, we will introduce the concept of weights of forms which will produce a splitting on the exterior differential operator d. We shall see how the Rumin complex arises from this splitting and proceed to carry out the complete computations in some key examples. From the third chapter onwards we will focus on Julg's paper, describing his new filtration and its relationship with the weight spectral sequence. We will study the connection between the spectral sequences and Rumin's complex in the n-dimensional Heisenberg group and the 7-dimensional quaternionic Heisenberg group and then generalize the result to Carnot groups using the weight filtration. Finally, we shall explain why Julg required the independence of choices in some special Rumin operators, introducing the Szego map and describing its main properties.

Vibrational spectroscopic and electrochemical investigations of multi-centered heme proteins in biomimetic membrane architectures

Membrane proteins play a major role in every living cell. They are the key factors in the cell’s metabolism and in other functions, for example in cell-cell interaction, signal transduction, and transport of ions and nutrients. Cytochrome c oxidase (CcO), as one of the membrane proteins of the respiratory chain, plays a significant role in the energy transformation of higher organisms. CcO is a multi centered heme protein, utilizing redox energy to actively transport protons across the mitochondrial membrane. One aim of this dissertation is to investigate single steps in the mechanism of the ion transfer process coupled to electron transfer, which are not fully understood. The protein-tethered bilayer lipid membrane is a general approach to immobilize membrane proteins in an oriented fashion on a planar electrode embedded in a biomimetic membrane. This system enables the combination of electrochemical techniques with surface enhanced resonance Raman (SERRS), surface enhanced reflection absorption infrared (SEIRAS), and surface plasmon spectroscopy to study protein mediated electron and ion transport processes. The orientation of the enzymes within the surface confined architecture can be controlled by specific site-mutations, i.e. the insertion of a poly-histidine tag to different subunits of the enzyme. CcO can, thus, be oriented uniformly with its natural electron pathway entry pointing either towards or away from the electrode surface. The first orientation allows an ultra-fast direct electron transfer(ET) into the protein, not provided by conventional systems, which can be leveraged to study intrinsic charge transfer processes. The second orientation permits to study the interaction with its natural electron donor cytochrome c. Electrochemical and SERR measurements show conclusively that the redox site structure and the activity of the surface confined enzyme are preserved. Therefore, this biomimetic system offers a unique platform to study the kinetics of the ET processes in order to clarify mechanistic properties of the enzyme. Highly sensitive and ultra fast electrochemical techniques allow the separation of ET steps between all four redox centres including the determination of ET rates. Furthermore, proton transfer coupled to ET could be directly measured and discriminated from other ion transfer processes, revealing novel mechanistic information of the proton transfer mechanism of cytochrome c oxidase. In order to study the kinetics of the ET inside the protein, including the catalytic center, time resolved SEIRAS and SERRS measurements were performed to gain more insight into the structural and coordination changes of the heme environment. The electrical behaviour of tethered membrane systems and membrane intrinsic proteins as well as related charge transfer processes were simulated by solving the respective sets of differential equations, utilizing a software package called SPICE. This helps to understand charge transfer processes across membranes and to develop models that can help to elucidate mechanisms of complex enzymatic processes.

SMO inhibitor specifically targets the Hedgehog Pathway and reverts the drug-resistance of Leukemic Stem Cells

Abnormal Hedgehog signaling is associated with human malignancies. Smo, a key player of that signaling, is the most suitable target to inhibit this pathway. To this aim several molecules, antagonists of Smo, have been synthesized, and some of them have started the phase I in clinical trials. Our hospital participated to one of these studies which investigated the oral administration of a new selective inhibitor of Smo (SMOi). To evaluate ex vivo SMOi efficacy and to identify new potential clinical biomarkers of responsiveness, we separated bone marrow CD34+ cells from 5 acute myeloid leukemia (AML), 1 myelofibrosis (MF), 2 blastic phases chronic myeloid leukemia (CML) patients treated with SMOi by immunomagnetic separation, and we analysed their gene expression profile using Affimetrix HG-U133 Plus 2.0 platform. This analysis, showed differential expression after 28 days start of therapy (p-value ≤ 0.05) of 1,197 genes in CML patients and 589 genes in AML patients. This differential expression is related to Hedgehog pathway with a p-value = 0.003 in CML patients and with a p-value = 0.0002 in AML patients, suggesting that SMOi targets specifically this pathway. Among the genes differentially expressed we observed strong up-regulation of Gas1 and Kif27 genes, which may work as biomarkers of responsiveness of SMOi treatment in CML CD34+ cells whereas Hedgehog target genes (such as Smo, Gli1, Gli2, Gli3), Bcl2 and Abca2 were down-regulated, in both AML and CML CD34+ cells. It has been reported that Bcl-2 expression could be correlated with cancer therapy resistance and that Hedgehog signaling modulate ATP-binding (ABC) cassette transporters, whose expression has been correlated with chemoresistance. Moreover we confirmed that in vitro SMOi treatment targets Hedgehog pathway, down-regulate ABC transporters, Abcg2 and Abcb1 genes, and in combination with tyrosine kinase inhibitors (TKIs) could revert the chemoresistance mechanism in K562 TKIs-resistant cell line.

Alterations of white matter integrity related to motor activity in schizophrenia

Altered structural connectivity is a key finding in schizophrenia, but the meaning of white matter alterations for behavior is rarely studied. In healthy subjects, motor activity correlated with white matter integrity in motor tracts. To explore the relation of motor activity and fractional anisotropy (FA) in schizophrenia, we investigated 19 schizophrenia patients and 24 healthy control subjects using Diffusion Tensor Imaging (DTI) and actigraphy on the same day. Schizophrenia patients had lower activity levels (AL). In both groups linear relations of AL and FA were detected in several brain regions. Schizophrenia patients had lower FA values in prefrontal and left temporal clusters. Furthermore, using a general linear model, we found linear negative associations of FA and AL underneath the right supplemental motor area (SMA), the right precentral gyrus and posterior cingulum in patients. This effect within the SMA was not seen in controls. This association in schizophrenia patients may contribute to the well known dysfunctions of motor control. Thus, structural disconnectivity could lead to disturbed motor behavior in schizophrenia.

A differential concentration-dependent effect of IVIg on neutrophil functions: relevance for anti-microbial and anti-inflammatory mechanisms

Background Polymorphonuclear neutrophils (PMN) play a key role in host defences against invading microorganisms but can also potentiate detrimental inflammatory reactions in case of excessive or misdirected responses. Intravenous immunoglobulins (IVIg) are used to treat patients with immune deficiencies and, at higher doses, in autoimmune, allergic and systemic inflammatory disorders. Methodology/Principal Findings We used flow cytometry to examine the effects of IVIg on PMN functions and survival, using whole-blood conditions in order to avoid artifacts due to isolation procedures. IVIg at low concentrations induced PMN activation, as reflected by decreased L-selectin and increased CD11b expression at the PMN surface, oxidative burst enhancement, and prolonged cell survival. In contrast, IVIg at higher concentrations inhibited LPS-induced CD11b degranulation and oxidative burst priming, and counteracted LPS-induced PMN lifespan prolongation. Conclusions/Significance IVIg appears to have differential, concentration-dependent effects on PMN, possibly supporting the use of IVIg as either an anti-microbial or an anti-inflammatory agent.

Induced hypoglycemia for 48 hours indicates differential glucose and insulin effects on liver metabolism in dairy cows

Hypoglycemia is a characteristic condition of early lactation dairy cows and is subsequently dependent on, and may affect, metabolism in the liver. The objective of the present study was to investigate the effects of induced hypoglycemia, maintained for 48 h, on metabolic parameters in plasma and liver of mid-lactation dairy cows. The experiment involved 3 treatments, including a hyperinsulinemic hypoglycemic clamp (HypoG, n=6) to obtain a glucose concentration of 2.5 mmol/L, a hyperinsulinemic euglycemic clamp (EuG, n=6) in which the effect of insulin was studied, and a control treatment with a 0.9% saline solution (NaCl, n=6). Blood samples for measurements of insulin, metabolites, and enzymes were taken at least once per hour. Milk yield was recorded and milk samples were collected before and after treatment. Liver biopsies were obtained before and after treatment to measure mRNA abundance by real-time, quantitative reverse transcription-PCR of 12 candidate genes involved in the main metabolic pathways. Milk yield decreased in HypoG and NaCl cows, whereas it remained unaffected in EuG cows. Energy-corrected milk yield (kg/d) was only decreased in HypoG cows. In plasma, concentration of beta-hydroxybutyrate decreased in response to treatment in EuG cows and was lower (0.41+/-0.04 mmol/L) on d 2 of the treatment compared with that in HypoG and NaCl cows (on average 0.61+/-0.03 mmol/L, respectively). Nonesterified fatty acids remained unaffected in all treatments. In the liver, differences between treatments for their effects were only observed in case of mitochondrial phosphoenolpyruvate carboxykinase (PEPCKm) and glucose-6-phosphatase (G6PC). In HypoG, mRNA abundance of PEPCKm was upregulated, whereas in EuG and NaCl cows, it was downregulated. The EuG treatment downregulated mRNA expression of G6PC, a marked effect compared with the unchanged transcript expression in NaCl. The mRNA abundance of the insulin receptor remained unaffected in all treatments, and no significant treatment differences were observed for genes related to lipid metabolism. In conclusion, low glucose concentrations in dairy cows affect liver metabolism at a molecular level through upregulation of PEPCKm mRNA abundance. Metabolic regulatory events in the liver are directed, apart from hormones, by the level of metabolites, either in excess (e.g., free fatty acids) or in shortage (e.g., glucose).

Expression profiling of stem cell-related genes in neoadjuvant-treated gastric cancer: a NOTCH2, GSK3B and β-catenin gene signature predicts survival

Cancer stem cell (CSC) based gene expression signatures are associated with prognosis in various tumour types and CSCs are suggested to be particularly drug resistant. The aim of our study was first, to determine the prognostic significance of CSC-related gene expression in residual tumour cells of neoadjuvant-treated gastric cancer (GC) patients. Second, we wished to examine, whether expression alterations between pre- and post-therapeutic tumour samples exist, consistent with an enrichment of drug resistant tumour cells. The expression of 44 genes was analysed in 63 formalin-fixed, paraffin embedded tumour specimens with partial tumour regression (10-50% residual tumour) after neoadjuvant chemotherapy by quantitative real time PCR low-density arrays. A signature of combined GSK3B(high), β-catenin (CTNNB1)(high) and NOTCH2(low) expression was strongly correlated with better patient survival (p<0.001). A prognostic relevance of these genes was also found analysing publically available gene expression data. The expression of 9 genes was compared between pre-therapeutic biopsies and post-therapeutic resected specimens. A significant post-therapeutic increase in NOTCH2, LGR5 and POU5F1 expression was found in tumours with different tumour regression grades. No significant alterations were observed for GSK3B and CTNNB1. Immunohistochemical analysis demonstrated a chemotherapy-associated increase in the intensity of NOTCH2 staining, but not in the percentage of NOTCH2. Taken together, the GSK3B, CTNNB1 and NOTCH2 expression signature is a novel, promising prognostic parameter for GC. The results of the differential expression analysis indicate a prominent role for NOTCH2 and chemotherapy resistance in GC, which seems to be related to an effect of the drugs on NOTCH2 expression rather than to an enrichment of NOTCH2 expressing tumour cells.

Sexual activity-related emergency department admissions: eleven years of experience at a Swiss university hospital

PRINCIPALS: Most people enjoy sexual intercourse without complications, but a significant, if small, number need to seek emergency medical help for related health problems. The true incidence of these problems is not known. We therefore assessed all admissions to our emergency department (ED) in direct relation to sexual intercourse. METHODS: All data were collected prospectively and entered into the ED's centralised electronic patient record database (Qualicare, Switzerland) and retrospectively analysed. The database was scanned for the standardised key words: 'sexual intercourse' (German 'Geschlechtsverkehr') or 'coitus' (German 'Koitus'). RESULTS: A total of 445 patients were available for further evaluation; 308 (69.0%) were male, 137 (31.0%) were female. The median age was 32 years (range 16-71) for male subjects and 30 years (range 16-70) for female subjects. Two men had cardiovascular emergencies. 46 (10.3%) of our patients suffered from trauma. Neurological emergencies occurred in 55 (12.4%) patients: the most frequent were headaches in 27 (49.0%), followed by subarachnoid haemorrhage (12, 22.0%) and transient global amnesia (11, 20.0%). 154 (97.0%) of the patients presenting with presumed infection actually had infections of the urogenital tract. The most common infection was urethritis (64, 41.0%), followed by cystitis (21, 13.0%) and epididymitis (19, 12.0%). A sexually transmitted disease (STD) was diagnosed in 43 (16.0%) of all patients presenting with a presumed infection. 118 (43.0%) of the patients with a possible infection requested testing for an STD because of unsafe sexual activity without underlying symptoms. CONCLUSIONS: Sexual activity is mechanically dangerous, potentially infectious and stressful for the cardiovascular system. Because information on ED presentation related to sexual intercourse is scarce, more efforts should be undertaken to document all such complications to improve treatment and preventative strategies.

Tracking the implicit self using event-related potentials

Negative biases in implicit self-evaluation are thought to be detrimental to subjective well-being and have been linked to various psychological disorders, including depression. An understanding of the neural processes underlying implicit self-evaluation in healthy subjects could provide a basis for the investigation of negative biases in depressed patients, the development of differential psychotherapeutic interventions, and the estimation of relapse risk in remitted patients. We thus studied the brain processes linked to implicit self-evaluation in 25 healthy subjects using event-related potential (ERP) recording during a self-relevant Implicit Association Test (sIAT). Consistent with a positive implicit self-evaluation in healthy subjects, they responded significantly faster to the congruent (self-positive mapping) than to the incongruent sIAT condition (self-negative mapping). Our main finding was a topographical ERP difference in a time window between 600 and 700 ms, whereas no significant differences between congruent and incongruent conditions were observed in earlier time windows. This suggests that biases in implicit self-evaluation are reflected only indirectly, in the additional recruitment of control processes needed to override the positive implicit self-evaluation of healthy subjects in the incongruent sIAT condition. Brain activations linked to these control processes can thus serve as an indirect measure for estimating biases in implicit self-evaluation. The sIAT paradigm, combined with ERP, could therefore permit the tracking of the neural processes underlying implicit self-evaluation in depressed patients during psychotherapy.

Cascading climate effects and related ecological consequences during past centuries

The interface between climate and ecosystem structure and function is incompletely understood, partly because few ecological records start before the recent warming phase. Here, we analyse an exceptional 100-yr long record of the great tit (Parus major) population in Switzerland in relation to climate and habitat phenology. Using structural equation analysis, we demonstrate an uninterrupted cascade of significant influences of the large-scale atmospheric circulation (North-Atlantic Oscillation, NAO, and North-sea – Caspian Pattern, NCP) on habitat and breeding phenology, and further on fitness-relevant life history traits within great tit populations. We then apply the relationships of this analysis to reconstruct the circulation-driven component of fluctuations in great tit breeding phenology and productivity on the basis of new seasonal NAO and NCP indices back to 1500 AD. According to the structural equation model, the multi-decadal oscillation of the atmospheric circulation likely led to substantial variation in habitat phenology, productivity and consequently, tit population fluctuations with minima during the "Maunder Minimum" (∼ 1650–1720) and the Little Ice Age Type Event I (1810–1850). The warming since 1975 was not only related with a quick shift towards earlier breeding, but also with the highest productivity since 1500, and thus, the impact of the NAO and NCP has contributed to an unprecedented increase of the population. A verification of the structural equation model against two independent data series (1970–2000 and 1750–1900) corroborates that the retrospective model reliably depicts the major long-term NAO/NCP impact on ecosystem parameters. The results suggest a complex cascade of climate effects beginning at a global scale and ending at the level of individual life histories. This sheds light on how large-scale climate conditions substantially affect major life history parameters within a population, and thus influence key ecosystem parameters at the scale of centuries.

Differential expression of IGF-I mRNA and peptide in the male and female gonad during early development of a bony fish, the tilapia Oreochromis niloticus

Insulin-like growth factor I (IGF-I) plays a key role in the complex system that regulates bony fish growth, differentiation, and reproduction. The major source of circulating IGF-I is liver, but IGF-I-producing cells also occur in other organs, including the gonads. Because no data are available on the potential production sites of IGF-I in gonad development, developmental stages of monosex breedings of male and female tilapia from 0 day postfertilization (DPF) to 90 DPF were investigated for the production sites of IGF-I at the peptide (immunohistochemistry) and mRNA (in situ hybridization) level. IGF-I mRNA first appeared in somatic cells of the male and female gonad anlage at 7 DPF followed by IGF-I peptide around 9-10 DPF. Gonad anlagen were detected from 7 DPF. Starting at 7 DPF, IGF-I peptide but no IGF-I mRNA was observed in male and female primordial germ cells (PGCs) provided that IGF-I mRNA was not under the detection level, this observation may suggest that IGF-I originates from the somatic cells and is transferred to the PGCs or is of maternal origin. While in female germ cells IGF-I mRNA and peptide appeared at 29 DPF, in male germ cells both were detected as late as at 51-53 DPF. It is assumed that the production of IGF-I in the germ cells is linked to the onset of meiosis that in tilapia ovary starts at around 28 DPF and in testes at around 52-53 DPF. In adult testis, IGF-I mRNA and peptide occurred in the majority of spermatogonia and spermatocytes as well as in Leydig cells, the latter indicating a role of IGF-I in the synthesis of male sex steroids. In adult ovary, IGF-I mRNA and IGF-I peptide were always present in small and previtellogenic oocytes but only IGF-I peptide infrequently occurred in oocytes at the later stages. IGF-I expression appeared in numerous granulosa and some theca cells of follicles at the lipid stage and persisted in follicles with mature oocytes. The results suggest a crucial role of local IGF-I in the formation, differentiation and function of tilapia gonads.

Reduced hippocampal anisotropy related to anteriorization of alpha EEG in schizophrenia

Dysfunctions of the hippocampus have been suggested to be related to schizophrenia, and reduced connectivity with other brain regions may be a key for the pathophysiology. The aim of this study was to investigate the effect of white matter anomalies in the hippocampus, as a sign of altered connectivity, on the brain electrical activity. We investigated seven first episode schizophrenic patients and seven age, gender and education-matched controls with diffusion tensor imaging and resting EEG. Fractional anisotropy was computed based on diffusion tensor imaging data for the right and left hippocampus for both groups. No group differences were found in hippocampal fractional anisotropy, EEG spectral power and topography. However a significant correlation was found between more anterior alpha activity and lower fractional anisotropy of both hippocampi in schizophrenics, but not in controls. More anterior alpha activity has been described in schizophrenia. We conclude that this feature might depict a group of schizophrenic patients with reduced hippocampal connectivity.

Primary care physician supply and other key determinants of health care utilisation: The case of Switzerland

Background The Swiss government decided to freeze new accreditations for physicians in private practice in Switzerland based on the assumption that demand-induced health care spending may be cut by limiting care offers. This legislation initiated an ongoing controversial public debate in Switzerland. The aim of this study is therefore the determination of socio-demographic and health system-related factors of per capita consultation rates with primary care physicians in the multicultural population of Switzerland. Methods The data were derived from the complete claims data of Swiss health insurers for 2004 and included 21.4 million consultations provided by 6564 Swiss primary care physicians on a fee-for-service basis. Socio-demographic data were obtained from the Swiss Federal Statistical Office. Utilisation-based health service areas were created and were used as observational units for statistical procedures. Multivariate and hierarchical models were applied to analyze the data. Results Models within the study allowed the definition of 1018 primary care service areas with a median population of 3754 and an average per capita consultation rate of 2.95 per year. Statistical models yielded significant effects for various geographical, socio-demographic and cultural factors. The regional density of physicians in independent practice was also significantly associated with annual consultation rates and indicated an associated increase 0.10 for each additional primary care physician in a population of 10,000 inhabitants. Considerable differences across Swiss language regions were observed with reference to the supply of ambulatory health resources provided either by primary care physicians, specialists, or hospital-based ambulatory care. Conclusion The study documents a large small-area variation in utilisation and provision of health care resources in Switzerland. Effects of physician density appeared to be strongly related to Swiss language regions and may be rooted in the different cultural backgrounds of the served populations.

Clinical significance of cell cycle- and apoptosis-related markers in biliary tract cancer: a tissue microarray-based approach revealing a distinctive immunophenotype for intrahepatic and extrahepatic cholangiocarcinomas

Cholangiocarcinoma is the second most common malignant tumor of the liver. We analyzed, immunohistochemically, the significance of cell cycle- and apoptosis-related markers in 128 cholangiocarcinomas (42 intrahepatic, 70 extrahepatic, and 16 gallbladder carcinomas) combined in a tissue microarray. Follow-up was available for 57 patients (44.5%). In comparison with normal tissue (29 specimens), cholangiocarcinomas expressed significantly more frequently p53, bcl-2, bax, and COX-2 (P.05 <). Intrahepatic tumors were significantly more frequently bcl-2+ and p16+, whereas extrahepatic tumors were more often p53+ (P < .05). Loss of p16 expression was associated with reduced survival of patients. Our data show that p53, bcl-2, bax, and COX-2 have an important role in the pathogenesis of cholangiocarcinomas. The differential expression of p16, bcl-2, and p53 between intrahepatic and extrahepatic tumors demonstrates that there are location-related differences in the phenotype and the genetic profiles of these tumors. Moreover, p16 was identified as an important prognostic marker in cholangiocarcinomas.

Lung epithelial apoptosis in influenza virus pneumonia: the role of macrophage-expressed TNF-related apoptosis-inducing ligand

Mononuclear phagocytes have been attributed a crucial role in the host defense toward influenza virus (IV), but their contribution to influenza-induced lung failure is incompletely understood. We demonstrate for the first time that lung-recruited "exudate" macrophages significantly contribute to alveolar epithelial cell (AEC) apoptosis by the release of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in a murine model of influenza-induced pneumonia. Using CC-chemokine receptor 2-deficient (CCR2(-/-)) mice characterized by defective inflammatory macrophage recruitment, and blocking anti-CCR2 antibodies, we show that exudate macrophage accumulation in the lungs of influenza-infected mice is associated with pronounced AEC apoptosis and increased lung leakage and mortality. Among several proapoptotic mediators analyzed, TRAIL messenger RNA was found to be markedly up-regulated in alveolar exudate macrophages as compared with peripheral blood monocytes. Moreover, among the different alveolar-recruited leukocyte subsets, TRAIL protein was predominantly expressed on macrophages. Finally, abrogation of TRAIL signaling in exudate macrophages resulted in significantly reduced AEC apoptosis, attenuated lung leakage, and increased survival upon IV infection. Collectively, these findings demonstrate a key role for exudate macrophages in the induction of alveolar leakage and mortality in IV pneumonia. Epithelial cell apoptosis induced by TRAIL-expressing macrophages is identified as a major underlying mechanism.