Publications by authors named "Karin Schmidt"

33 Publications

NewBG: A surrogate corticosteroid-binding globulin with an unprecedentedly high ligand release efficacy.

J Struct Biol 2019 08 16;207(2):169-182. Epub 2019 May 16.

Division of Biotechnology, Department of Biology, Friedrich-Alexander-University Erlangen-Nuremberg, Henkestr. 91, D-91052 Erlangen, Germany. Electronic address:

The introduction of ligand-binding sites into proteins and the engineering of molecular allosteric coupling pathways are topical issues in protein design. Here, we show that these issues can be addressed concurrently, using the serpin human α1-antichymotrypsin (ACT) as a model. We have introduced up to 15 amino acid substitutions into ACT, converting it into a surrogate corticosteroid-binding globulin (CBG), thereby creating a new binding globulin (NewBG). Human CBG and ACT share 46% sequence identity, and CBG served as the blue-print for our design, which was guided by side-chain-packing calculations, ITC measurements and crystal structure determinations. Upon transfer of ligand-interacting residues from CBG to ACT and mutation of specific second shell residues, a NewBG variant was obtained, which binds cortisol with 1.5 µM affinity. This novel serpin (NewBG-III) binds cortisol with a 33-fold lower affinity than CBG, but shares a similar ligand-binding profile and binding mode when probed with different steroid ligands and site-directed mutagenesis. An additional substitution, i.e. A349R, created NewBG-III-allo, which introduced an allosteric coupling between ligand binding and the serpin-like S-to-R transition in ACT. In NewBG-III-allo, the proteinase-triggered S-to-R transition leads to a greater than 200-fold reduction in ligand affinity, and crystal structures suggest that this is mediated by the L55V and A349R substitutions. This reduction significantly exceeds the 10-fold reduction in binding affinity observed in human CBG.
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http://dx.doi.org/10.1016/j.jsb.2019.05.006DOI Listing
August 2019

PRISEs (progesterone 5β-reductase and/or iridoid synthase-like 1,4-enone reductases): Catalytic and substrate promiscuity allows for realization of multiple pathways in plant metabolism.

Phytochemistry 2018 Dec 29;156:9-19. Epub 2018 Aug 29.

Division of Pharmaceutical Biology, Department of Biology, Friedrich-Alexander-University Erlangen-Nürnberg, D-91058 Erlangen, Germany. Electronic address:

PRISEs (progesterone 5β-reductase and/or iridoid synthase-like 1,4-enone reductases) are involved in cardenolide and iridoid biosynthesis. We here investigated a PRISE (rAtSt5βR) from Arabidopsis thaliana, a plant producing neither cardenolides nor iridoids. The structure of rAtSt5βR was elucidated with X-ray crystallography and compared to the known structures of PRISEs from Catharanthus roseus (rCrISY) and Digitalis lanata (rDlP5βR). The three enzymes show a high degree of sequence and structure conservation in the active site. Amino acids previously considered to allow discrimination between progesterone 5β-reductase and iridoid synthase were interchanged among rAtSt5βR, rCrISY and rDlP5βR applying site-directed mutagenesis. Structural homologous substitutions had different effects, and changes in progesterone 5β-reductase and iridoid synthase activity were not correlated in all cases. Our results help to explain fortuitous emergence of metabolic pathways and product accumulation. The fact that PRISEs are found ubiquitously in spermatophytes insinuates that PRISEs might have a more general function in plant metabolism such as, for example, the detoxification of reactive carbonyl species.
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http://dx.doi.org/10.1016/j.phytochem.2018.08.012DOI Listing
December 2018

Design of an allosterically modulated doxycycline and doxorubicin drug-binding protein.

Proc Natl Acad Sci U S A 2018 05 14;115(22):5744-5749. Epub 2018 May 14.

Department of Biotechnology, Friedrich-Alexander University Erlangen-Nuremberg, 91054 Erlangen, Germany;

The allosteric interplay between distant functional sites present in a single protein provides for one of the most important regulatory mechanisms in biological systems. While the design of ligand-binding sites into proteins remains challenging, this holds even truer for the coupling of a newly engineered binding site to an allosteric mechanism that regulates the ligand affinity. Here it is shown how computational design algorithms enabled the introduction of doxycycline- and doxorubicin-binding sites into the serine proteinase inhibitor (serpin) family member α1-antichymotrypsin. Further engineering allowed exploitation of the proteinase-triggered serpin-typical S-to-R transition to modulate the ligand affinities. These design variants follow strategies observed in naturally occurring plasma globulins that allow for the targeted delivery of hormones in the blood. By analogy, we propose that the variants described in the present study could be further developed to allow for the delivery of the antibiotic doxycycline and the anticancer compound doxorubicin to tissues/locations that express specific proteinases, such as bacterial infection sites or tumor cells secreting matrix metalloproteinases.
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http://dx.doi.org/10.1073/pnas.1716666115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5984491PMC
May 2018

ERAP1-Dependent Antigen Cross-Presentation Determines Efficacy of Adoptive T-cell Therapy in Mice.

Cancer Res 2018 06 20;78(12):3243-3254. Epub 2018 Mar 20.

Institute of Biochemistry, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany.

Cytotoxic T lymphocytes can reject established tumors if their target peptide is efficiently presented by MHC class I molecules (pMHC-I) on the surface of cancerous cells. Therapeutic success upon adoptive T-cell transfer (ATT), however, requires additional cross-presentation of the same pMHC-I on noncancerous cells. Endoplasmic reticulum aminopeptidase 1 (ERAP1) is an enzyme that customizes the N-terminus of proteasome-generated peptides so they can be loaded onto MHC-I molecules in the endoplasmic reticulum (ER). We show here that ERAP1 is critically involved in the process of tumor rejection and assumes a dual role by independently operating on both sides. Direct presentation of two MHC-I-restricted epitopes of a cancer-driving transplantation rejection antigen through ERAP1 moderately affected tumor rejection by adoptively transferred T-cell receptor gene-modified T cells in each case. ERAP1 expression by antigen cross-presenting cells of the ATT recipients was critical for expansion of therapeutic monospecific T cells and correlated with tumor rejection. Specifically, lack of ERAP1 expression in the ATT recipient's noncancerous cells enabled progression of pMHC-I-positive, IFNγ-responsive tumors, despite the presence of antigen-specific functional cytotoxic T lymphocytes. These data reveal a decisive role for ERAP1 in T-cell-mediated tumor rejection and will enhance the choice of MHC-I-restricted epitopes targeted by adoptive T-cell transfer. This study demonstrates a role of ERAP1 in the efficacy of adoptive T-cell transfer and has potential to improve personalized T-cell therapy for solid tumors. .
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http://dx.doi.org/10.1158/0008-5472.CAN-17-1946DOI Listing
June 2018

Sex Differences in Percutaneous Coronary Intervention-Insights From the Coronary Angiography and PCI Registry of the German Society of Cardiology.

J Am Heart Assoc 2017 Mar 20;6(3). Epub 2017 Mar 20.

Stiftung Institut für Herzinfarktforschung Ludwigshafen, Ludwigshafen, Germany.

Background: Several studies have suggested sex-related differences in diagnostic and invasive therapeutic coronary procedures.

Methods And Results: Data from consecutive patients who were enrolled in the Coronary Angiography and PCI Registry of the German Society of Cardiology were analyzed. We aimed to compare sex-related differences in in-hospital outcomes of patients undergoing percutaneous coronary intervention (PCI) for stable coronary artery disease, non-ST elevation acute coronary syndromes, ST elevation myocardial infarction, and cardiogenic shock. From 2007 until the end of 2009 data from 185 312 PCIs were prospectively registered: 27.9% of the PCIs were performed in women. Primary PCI success rate was identical between the sexes (94%). There were no sex-related differences in hospital mortality among patients undergoing PCI for stable coronary artery disease, non-ST elevation acute coronary syndromes, or cardiogenic shock except among ST elevation myocardial infarction patients. Compared to men, women undergoing primary PCI for ST elevation myocardial infarction have a higher risk of in-hospital death, age-adjusted odds ratio (1.19, 95% CI 1.06-1.33), and risk of ischemic cardiac and cerebrovascular events (death, myocardial infarction, transient ischemic attack/stroke), (age-adjusted odds ratio 1.19, 95% CI 1.16-1.29). Furthermore, access-related complications were twice as high in women, irrespective of the indication.

Conclusions: Despite identical technical success rates of PCI between the 2 sexes, women with PCI for ST elevation myocardial infarction have a 20% higher age-adjusted risk of death and of ischemic cardiac and cerebrovascular events. Further research is needed to determine the reasons for these differences.
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http://dx.doi.org/10.1161/JAHA.116.004972DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5524024PMC
March 2017

Preventing tumor escape by targeting a post-proteasomal trimming independent epitope.

J Exp Med 2016 10 3;213(11):2333-2348. Epub 2016 Oct 3.

Max-Delbrück-Center for Molecular Medicine, 13125 Berlin, Germany

Adoptive T cell therapy (ATT) can achieve regression of large tumors in mice and humans; however, tumors frequently recur. High target peptide-major histocompatibility complex-I (pMHC) affinity and T cell receptor (TCR)-pMHC affinity are thought to be critical to preventing relapse. Here, we show that targeting two epitopes of the same antigen in the same cancer cells via monospecific T cells, which have similar pMHC and pMHC-TCR affinity, results in eradication of large, established tumors when targeting the apparently subdominant but not the dominant epitope. Only the escape but not the rejection epitope required postproteasomal trimming, which was regulated by IFN-γ, allowing IFN-γ-unresponsive cancer variants to evade. The data describe a novel immune escape mechanism and better define suitable target epitopes for ATT.
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http://dx.doi.org/10.1084/jem.20160636DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5068242PMC
October 2016

Gender differences in therapeutic recommendation after diagnostic coronary angiography: insights from the Coronary Angiography and PCI Registry of the German Society of Cardiology.

Clin Res Cardiol 2015 Jun 21;104(6):507-17. Epub 2015 Jan 21.

Department of Cardiology, Krankenhaus Agatharied, Academic Teaching Hospital, University of Munich, Norbert-Kerkel-Platz, 83607, Hausham, Germany,

Background: There is information suggesting differences and underuse of invasive coronary diagnostic and therapeutic procedures in women compared to men.

Methods: Data from consecutive patients (pts) which were enrolled in the Coronary Angiography and PCI Registry of the German Society of Cardiology were analyzed. We compared gender-related differences in diagnosis and therapeutic recommendation of pts undergoing coronary angiography (XA) for stable coronary artery disease (CAD), non-ST elevation acute coronary syndromes (NSTE-ACS) and ST elevation myocardial infarction (STEMI).

Results: From 2004 until the end of 2009, data of 1,060,542 invasive procedures in 1,014,996 pts were prospectively registered. One-third (34.6%) of them were female. Women less often had significant CAD, irrespective of the indication for XA. In pts with relevant CAD, percutaneous coronary interventions (PCI) were recommended in 87.1% of women versus 89.1% of men with STEMI [age-adjusted OR (aOR) 0.98, 95% CI 0.93-1.04], in 67.1 vs. 66.8% in NSTE-ACS (aOR 1.10, 1.07-1.12), and in 50.3 vs 49.4% in stable CAD (aOR 1.07, 1.05-1.09).

Conclusions: In pts with significant CAD, there was no difference in recommendation for PCI between the genders in stable CAD, whereas in STEMI and NSTE-ACS women were treated even more often with PCI. There were only minor differences in referral for CABG between women and men. Hence, our data provide strong evidence against a gender bias in use of invasive therapeutic procedures once the diagnosis of significant CAD has been confirmed.
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http://dx.doi.org/10.1007/s00392-015-0815-6DOI Listing
June 2015

Use and impact of thrombectomy in primary percutaneous coronary intervention for acute myocardial infarction with persistent ST-segment elevation: results of the prospective ALKK PCI-registry.

Clin Res Cardiol 2015 Oct 25;104(10):803-11. Epub 2015 Mar 25.

Klinik für Kardiologie, Klinikum Oldenburg gGmbH, European Medical School Oldenburg-Groningen, Carl von Ossietzky Universität Oldenburg, Rahel-Straus-Str. 10, 26133, Oldenburg, Germany.

Background: Data about the impact of thrombectomy in primary percutaneous coronary intervention (PCI) are inconsistent. The aim of our study was an evaluation of both the real-world use of thrombectomy and the impact of thrombectomy on outcome in unselected patients treated with primary PCI for ST-elevation myocardial infarction (STEMI).

Methods And Results: We used the data of the prospective ALKK PCI-registry of 35 hospitals from January 2010 to December 2013. A total of 10,755 patients receiving single-vessel primary PCI for acute STEMI were included. In 2176 patients (20.2 %) thrombectomy was performed. There was a wide range of use of thrombectomy in the different ALKK hospitals from 1.1 to 61.7 % (median 18.6 %, quartiles 6.0 and 40.3 %) with a general increase of use over the first years of the study period. In patients with and without thrombectomy there was TIMI 0 flow present before PCI in 6010 patients, TIMI 1 in 1338, TIMI 2 in 2002, and TIMI 3 in 1405. Patients with acute heart failure or cardiogenic shock received significantly more often thrombectomy. Fluoroscopy time (8.1 vs. 7.3 min, p < 0.0001) and dose area product (5373 cGy × cm(2) vs. 4802 cGy × cm(2), p < 0.0001) were significantly higher in patients treated with thrombectomy. The subgroup of patients with TIMI 0 flow before PCI had significantly higher rates of TIMI 3 flow after PCI when treated with thrombectomy (87.1 vs. 84.1 %, p < 0.01), while there was no difference in post-PCI TIMI 3 flow in patients with TIMI 1, 2 or 3 flow before PCI. Rates of major adverse cardiac and cerebrovascular events were similar in both groups in general and in all subgroups of TIMI flow.

Conclusions: The use of thrombectomy in patients with STEMI is heterogenous between hospitals. Overall, there was no impact of thrombectomy on TIMI 3 patency or mortality after PCI. In the subgroup of STEMI patients with TIMI 0 flow before PCI individualized thrombectomy had a positive impact on restoration of normal blood flow.
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http://dx.doi.org/10.1007/s00392-015-0846-zDOI Listing
October 2015

Prevalence of depressive symptoms and associated developmental disorders in preschool children: a population-based study.

Eur Child Adolesc Psychiatry 2014 Apr 10;23(4):219-24. Epub 2013 Jul 10.

Department of Child and Adolescent Psychiatry, Saarland University Hospital, Homburg, 66421, Germany.

Depression is an incapacitating disorder, which is often overlooked in preschool children. The aim of this study was to analyse the prevalence of depressive symptoms and co-occurring risk factors in a large, population-based sample of preschool children. All 653 children (of a total of 731) in a defined geographical area were assessed during the school-entry exam by community care paediatricians. In addition to clinical appraisal, parents filled out the Preschool Feelings Checklist, a 16-item screening instrument with good psychometric properties. The mean age was 6.2 years (range 5.0-7.6 years) and the sample included 344 boys and 305 girls. The prevalence of depressive symptoms of clinical relevance (total score ≥3) was 5.7% (37). There were no differences between boys and girls, and between younger (<6 years) and older (>6 years) children. Depressive symptoms were associated with parental separation and comorbid behavioural problems, but especially with developmental motor and speech problems and disorders. Migration to Germany had no influence. Depressive symptoms are common in preschool children and associated with developmental problems. Depression should be considered in children with speech and motor problems who are at special risk. Early detection and treatment are recommended.
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http://dx.doi.org/10.1007/s00787-013-0452-4DOI Listing
April 2014

Virus-induced hepatocellular carcinomas cause antigen-specific local tolerance.

J Clin Invest 2013 Mar 1;123(3):1032-43. Epub 2013 Feb 1.

Institute of Immunology, Charité Campus Benjamin Franklin, Berlin, Germany.

T cell surveillance is often effective against virus-associated tumors because of their high immunogenicity. It is not clear why surveillance occasionally fails, particularly against hepatitis B virus- or hepatitis C virus-associated hepatocellular carcinoma (HCC). We established a transgenic murine model of virus-induced HCC by hepatocyte-specific adenovirus-induced activation of the oncogenic SV40 large T antigen (TAg). Adenovirus infection induced cytotoxic T lymphocytes (CTLs) targeted against the virus and TAg, leading to clearance of the infected cells. Despite the presence of functional, antigen-specific T cells, a few virus-infected cells escaped immune clearance and progressed to HCC. These cells expressed TAg at levels similar to HCC isolated from neonatal TAg-tolerant mice, suggesting that CTL clearance does not select for cells with low immunogenicity. Virus-infected mice revealed significantly greater T cell infiltration in early-stage HCC compared with that in late-stage HCC, demonstrating progressive local immune suppression through inefficient T cell infiltration. Programmed cell death protein-1 (PD-1) and its ligand PD-L1 were expressed in all TAg-specific CD8+ T cells and HCC, respectively, which contributed to local tumor-antigen-specific tolerance. Thus, we have developed a model of virus-induced HCC that may allow for a better understanding of human HCC.
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http://dx.doi.org/10.1172/JCI64742DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3582129PMC
March 2013

Fas expression by tumor stroma is required for cancer eradication.

Proc Natl Acad Sci U S A 2013 Feb 22;110(6):2276-81. Epub 2013 Jan 22.

Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany.

The contribution of molecules such as perforin, IFN-γ (IFNγ), and particularly Fas ligand (FasL) by transferred CD8(+) effector T (T(E)) cells to rejection of large, established tumors is incompletely understood. Efficient attack against large tumors carrying a surrogate tumor antigen (mimicking a "passenger" mutation) by T(E) cells requires action of IFNγ on tumor stroma cells to avoid selection of antigen-loss variants. Because "cancer-driving" antigens (CDAs) are rarely counterselected, IFNγ may be expected to be dispensable in elimination of cancers by targeting a CDA. Here, initial regression of large, established tumors required neither IFNγ, FasL, nor perforin by transferred CD8(+) T(E) cells targeting Simian Virus (SV) 40 large T as CDA. However, cytotoxic T(E) cells lacking IFNγ or FasL could not prevent relapse despite retention of the rejection antigen by the cancer cells. Complete tumor rejection required IFNγ-regulated Fas by the tumor stroma. Therefore, T(E) cells lacking IFNγ or FasL cannot prevent progression of antigenic cancer because the tumor stroma escapes destruction if its Fas expression is down-regulated.
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http://dx.doi.org/10.1073/pnas.1218295110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3568383PMC
February 2013

Differently immunogenic cancers in mice induce immature myeloid cells that suppress CTL in vitro but not in vivo following transfer.

Blood 2013 Mar 10;121(10):1740-8. Epub 2013 Jan 10.

Institute of Immunology, Charité Campus Buch, Berlin, Germany.

Tumors frequently induce immature myeloid cells (iMC), which suppress specific and unrelated cytotoxic T lymphocyte (CTL) responses and are termed myeloid-derived suppressor cells (MDSC). Mainly analyzed by in vitro assays in tumor transplantation models, little is known about their function in autochthonous tumor models in vivo. We analyzed iMC in 3 SV40 large T (Tag)-driven conditional autochthonous cancer models with different immune status: (1) Early Tag-specific CTL competence and rare stochastic Tag activation leading to sporadic cancer, which induces an aberrant immune response and CTL tolerance; (2) Cre/LoxP recombinase-mediated hepatocellular carcinoma (HCC) development in neonatal Tag-tolerant mice; and (3) Tag-activation through Cre recombinase-encoding viruses in the liver and HCC development with systemic anti-Tag CTL immunity. In the first but not two latter models, tumors induced CTL hyporesponsiveness to tumor-unrelated antigens. Regardless of the model, tumors produced interleukin-6 and vascular endothelial growth factor but not granulocyte macrophage–colony-stimulating factor (GM-CSF) and induced iMC (CD11b(+)Gr-1(int)) that suppressed CTL responses in vitro. None of the iMC from the different tumor models suppressed CTL responses in adoptive cell transfer experiments unless GM-CSF was provided in vivo. Together, iMC expand independent of the type of antitumor response and are not immunosuppressive in a cell-autonomous fashion.
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http://dx.doi.org/10.1182/blood-2012-06-436568DOI Listing
March 2013

Headache, menstruation and combined oral contraceptives: a diary study in 184 women with migraine.

Eur J Pain 2011 Sep 12;15(8):852-7. Epub 2011 Mar 12.

Department of Neurology, Medical University of Vienna, Austria.

Half of female migraineurs in childbearing age use combined oral contraceptives (COCs), but the influence of COCs on perimenstrual migraine is still unclear. We therefore aimed to analyze the risk of occurrence and persistence (i.e. presence for more than 1 day) of headache and migraine before and during menstruation in women with migraine, comparing users of COCs to non-users. We included 184 women with at least 1 day of menstruation recorded in a 90-day diary. We differentiated between (a) the 2 days before menstruation, (b) the first 3 days of menstruation and (c) the remaining days of menstruation and analyzed subgroups of women with (n=82) and without (n=102) COCs. In both groups, risk of any headache as well as that of migraine was highest during the first 3 days of menstruation with a hazard ratio of 1.9 and 2.1 for non-users and 2.1 and 2.2 for users. Although use of COCs showed no statistically significant overall effect, users were at higher risk for any headache premenstrually and non-users at higher risk for migraine on days 4+ of menstruation. In conclusion, use of COCs exerts only subtle differences on the course of perimenstrual migraine in menstruating women with migraine.
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http://dx.doi.org/10.1016/j.ejpain.2011.02.003DOI Listing
September 2011

Migraine and weather: a prospective diary-based analysis.

Cephalalgia 2011 Mar 26;31(4):391-400. Epub 2010 Nov 26.

Medical University of Vienna, Austria.

Aims: Weather is mentioned as a trigger factor by migraine patients most frequently. We examined the impact of meteorological factors and the impact of their day-to-day change on the risk of occurrence and persistence of headache and migraine and the correlation of subjective weather perception with objective weather data.

Methods: We performed a prospective, diary-based cohort study in 238 patients suffering from migraine with or without aura. Patients had to live within 25 km of the Vienna meteorological station and were required to keep a diary for 90 days. We analysed 11 meteorological parameters and 17 synoptic weather situations. For evaluating the hazard of occurrence and persistence of migraine and headache, we performed a univariate and a stepwise multivariate Cox regression analysis. We calculated correlations between subjective weather perception and meteorological data.

Results: In the uni- and multivariate analysis, a ridge of high pressure increased the risk of headache occurrence, lower mean daily wind speed increased the risk of migraine occurrence and a day-to-day change of daily sunshine duration increased the risk of migraine occurrence. A day-to-day change of the daily minimum temperature decreased the risk of migraine persistence. After correction for multiple testing, none of these findings remained statistically significant. Subjective weather perceptions did not correlate with the occurrence or persistence of migraine or headache. Subjective perception of cold and too-cold weather and of too-warm weather correlated with daily minimum, mean and maximum temperature.

Conclusion: The influence of weather factors on migraine and headache is small and questionable.
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http://dx.doi.org/10.1177/0333102410385580DOI Listing
March 2011

Characteristics, impact and treatment of 6000 headache attacks: the PAMINA study.

Eur J Pain 2011 Feb 23;15(2):205-12. Epub 2010 Jul 23.

Department of Neurology, Medical University of Vienna, Vienna, Austria.

The aim of this study was to prospectively evaluate the characteristics of headache attacks, their impact on daily activities as well as the type and efficacy of acute medication in patients with migraine. We included 281 patients with episodic migraine (87% females, aged 41.2±12.1). All patients kept a headache diary for 3 months covering headache characteristics, therapy and questions adopted from the Headache Impact Test (HIT-6) for rating the impact of each single headache attack (HIT-6s). For evaluating the efficacy of acute medication we compared triptans with other compounds using headache duration as outcome parameter. Of 6051 headache attacks 52.8% fulfilled the ICHD-II criteria of migraine. The HIT-6s score was 2.4±2.2 (range 0-6). It was lowest in untreated headaches (2.0±2.1) and highest in those treated with a combination of triptans and other compounds (4.1±2.0, p<0.001). Patients used triptans on 8.0% of all headache days, other compounds on 33.1%, a combination of both on 1.5% and no medication on 57.3% of the headache days. Migraine attacks of moderate or severe intensity treated with triptans alone lasted significantly shorter than those treated with other compounds (5.1±3.6 vs. 6.9±5.3h, p<0.001). In conclusion, almost 50% of the headaches occurring in patients with migraine do not fulfill migraine criteria. Use of triptans is associated with a shorter duration of moderate and severe migraine attacks compared to use of other compounds.
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http://dx.doi.org/10.1016/j.ejpain.2010.06.013DOI Listing
February 2011

Electronic and vibronic contributions to two-photon absorption in donor-acceptor-donor squaraine chromophores.

Chemistry 2008 ;14(35):11082-91

School of Chemistry and Biochemistry and Center of Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.

Many squaraines have been observed to exhibit two-photon absorption at transition energies close to those of the lowest energy one-photon electronic transitions. Here, the electronic and vibronic contributions to these low-energy two-photon absorptions are elucidated by performing correlated quantum-chemical calculations on model chromophores that differ in their terminal donor groups (diarylaminothienyl, indolenylidenemethyl, dimethylaminopolyenyl, or 4-(dimethylamino)phenylpolyenyl). For squaraines with diarylaminothienyl and dimethylaminopolyenyl donors and for the longer examples of 4-(dimethylamino)phenylpolyenyl donors, the calculated energies of the lowest two-photon active states approach those of the lowest energy one-photon active (1B(u)) states. This is consistent with the existence of purely electronic channels for low-energy two-photon absorption (TPA) in these types of chromophores. On the other hand, for all squaraines containing indolinylidenemethyl donors, the calculations indicate that there are no low-lying electronic states of appropriate symmetry for TPA. Actually, we find that the lowest energy TPA transitions can be explained through coupling of the one-photon absorption (OPA) active 1B(u) state with b(u) vibrational modes. Through implementation of Herzberg-Teller theory, we are able to identify the vibrational modes responsible for the low-energy TPA peak and to reproduce, at least qualitatively, the experimental TPA spectra of several squaraines of this type.
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http://dx.doi.org/10.1002/chem.200801055DOI Listing
January 2009

Magnetic resonance-derived 3-dimensional blood flow patterns in the main pulmonary artery as a marker of pulmonary hypertension and a measure of elevated mean pulmonary arterial pressure.

Circ Cardiovasc Imaging 2008 Jul;1(1):23-30

Siemens Medical Solutions, Graz, Austria.

Background: Pulmonary hypertension is a disease characterized by an elevation in pulmonary arterial pressure that is diagnosed invasively via right heart catheterization. Such pathological altered pressures in the pulmonary vascular system should lead to changes in blood flow patterns in the main pulmonary artery.

Methods And Results: Forty-eight subjects (22 with manifest pulmonary hypertension, 13 with latent pulmonary hypertension, and 13 normal control subjects) underwent time-resolved 3D magnetic resonance phase-contrast imaging of the main pulmonary artery. Velocity fields that resulted from measurements were calculated, visualized, and analyzed with dedicated software. Main findings were as follows: (1) Manifest pulmonary hypertension coincides with the appearance of a vortex of blood flow in the main pulmonary artery (sensitivity and specificity of 1.00, 95% confidence intervals of 0.84 to 1.00 and 0.87 to 1.00, respectively), and (2) the relative period of existence of the vortex correlates significantly with mean pulmonary arterial pressure at rest (correlation coefficient of 0.94). To test the diagnostic performance of the vortex criterion, we furthermore investigated 55 patients in a blinded prospective study (22 with manifest pulmonary hypertension, 32 with latent pulmonary hypertension, and 1 healthy subject), which resulted in a sensitivity of 1.00 and specificity of 0.91 (95% confidence intervals of 0.84 to 1.00 and 0.76 to 0.98, respectively). Comparison of catheter-derived mean pulmonary artery pressure measurements and calculated mean pulmonary artery pressure values resulted in a standard deviation of differences of 3.6 mm Hg.

Conclusions: Vortices of blood flow in the main pulmonary artery enable the identification of manifest pulmonary hypertension. Elevated mean pulmonary arterial pressures can be measured from the period of vortex existence.
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http://dx.doi.org/10.1161/CIRCIMAGING.108.780247DOI Listing
July 2008

Immunogenicity of premalignant lesions is the primary cause of general cytotoxic T lymphocyte unresponsiveness.

J Exp Med 2008 Jul 23;205(7):1687-700. Epub 2008 Jun 23.

Institute of Immunology, Charité Campus Benjamin Franklin, 12200 Berlin, Germany.

Cancer is sporadic in nature, characterized by an initial clonal oncogenic event and usually a long latency. When and how it subverts the immune system is unknown. We show, in a model of sporadic immunogenic cancer, that tumor-specific tolerance closely coincides with the first tumor antigen recognition by B cells. During the subsequent latency period until tumors progress, the mice acquire general cytotoxic T lymphocyte (CTL) unresponsiveness, which is associated with high transforming growth factor (TGF) beta1 levels and expansion of immature myeloid cells (iMCs). In mice with large nonimmunogenic tumors, iMCs expand but TGF-beta1 serum levels are normal, and unrelated CTL responses are undiminished. We conclude that (a) tolerance to the tumor antigen occurs at the premalignant stage, (b) tumor latency is unlikely caused by CTL control, and (c) a persistent immunogenic tumor antigen causes general CTL unresponsiveness but tumor burden and iMCs per se do not.
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http://dx.doi.org/10.1084/jem.20072016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2442645PMC
July 2008

Gastric dilatation-volvulus associated with diaphragmatic hernia in three cats: clinical presentation, surgical treatment and presumptive aetiology.

J Feline Med Surg 2008 Apr 21;10(2):198-201. Epub 2007 Dec 21.

Lago Maggiore Veterinary Clinic, C.so Cavour 3, 28040 Dormelletto (NO), Italy.

Three cats were examined because of acute dyspnoea and sudden abdominal enlargement. In all cats, radiographs revealed gastric dilatation-volvulus (GDV) and diaphragmatic hernia. Cardiovascular shock and dyspnoea were treated by intravenous fluid-therapy, oxygen administration and relief of diaphragmatic pressure by means of stomach decompression and in one case placing the patient in an inclined position. Gastric decompression was performed by needle gastrocentesis, placement of a rhino-gastric tube, or a combination of these. Diaphragmatic herniorrhaphy was performed in either case; one cat also underwent gastropexy. The immediate postoperative period resolved uneventfully and the cats were doing well at follow-up. Feline GDV is a rare event in which diaphragmatic hernia may be a predisposing factor.
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http://dx.doi.org/10.1016/j.jfms.2007.09.010DOI Listing
April 2008

Intersystem crossing processes in nonplanar aromatic heterocyclic molecules.

J Phys Chem A 2007 Oct 2;111(42):10490-9. Epub 2007 Oct 2.

School of Chemistry and Biochemistry and Center of Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.

A comprehensive study of the photophysical properties of a series of monoaza[5]helicenes is presented on the basis of joint optical spectroscopy and quantum chemistry investigations. The molecules have been characterized by absorption and CW/time-resolved luminescence measurements. All quantities related to spin-orbit-coupling processes, such as intersystem crossing rates and radiative phosphorescence lifetimes, were found to depend strongly on the nitrogen position within the carbon backbone. Density functional theory and semiempirical quantum-chemical methods were used to evaluate the molecular geometries, the characteristics of the excited singlet and triplet states, and the spin-orbit coupling matrix elements. We demonstrate that the magnitude of spin-orbit coupling is directly correlated with the degree of deviation from planarity. The trends from the calculated photophysical quantities, namely, radiative fluorescence and phosphorescence decay rates and intersystem crossing rates, of the mono-aza-helicenes are fully consistent with experiment.
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http://dx.doi.org/10.1021/jp075248qDOI Listing
October 2007

Design of emission ratiometric metal-ion sensors with enhanced two-photon cross section and brightness.

J Am Chem Soc 2007 Oct 11;129(39):11888-9. Epub 2007 Sep 11.

School of Chemistry and Biochemistry, Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332, USA.

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http://dx.doi.org/10.1021/ja073240oDOI Listing
October 2007

Structure to property relationships for multiphoton absorption in covalently linked porphyrin dimers: a correction vector INDO/MRDCI study.

J Phys Chem A 2007 Aug 4;111(34):8509-18. Epub 2007 Aug 4.

Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, 100080 Beijing, P. R. China.

The correction vector method has been used to investigate structure to property relationships for multiphoton absorption properties in covalently linked porphyrin dimers. The electronic structure of the system is described within the multireference single and double configuration interaction (MRDCI) method coupled with the intermediate neglect of differential overlap (INDO) Hamiltonian. We find a strong increase in the two-photon absorption (2PA) and three-photon absorption (3PA) cross sections when going from an isolated porphyrin to the dimers. The nature of the 2PA and 3PA active states as well as the cross sections show a strong but not straightforward dependence on the length of the bridge between the two porphyrins. Our theoretical results are in very good agreement with experimental data for 2PA. The resulting structure to property relationships are analyzed on the basis of essential-state models, where it turns out that a three-state model considering only the Q(x) intermediate state proposed in literature does not provide a full description of the actual situation.
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http://dx.doi.org/10.1021/jp072670yDOI Listing
August 2007

Excited state intramolecular proton transfer in 2-(2'-arylsulfonamidophenyl)benzimidazole derivatives: insights into the origin of donor substituent-induced emission energy shifts.

J Phys Chem A 2007 May 10;111(21):4584-95. Epub 2007 May 10.

School of Chemistry and Biochemistry and Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332-0400, USA.

Donor-substituted 2-(2'-arylsulfonamidophenyl)benzimidazoles undergo efficient excited-state intramolecular proton transfer (ESIPT) upon photoexcitation. The tautomer emission energy depends strongly on the substituent attachment position on the fluorophore pi-system. While substitution with a donor group in the para-position relative to the sulfonamide moiety yields an emission energy that is red-shifted relative to the unsubstituted fluorophore, fluorescence of the meta-substituted derivative appears blue-shifted. To elucidate the origin of the surprisingly divergent emission shifts, we performed detailed photophysical and quantum chemical studies with a series of methoxy- and pyrrole-substituted derivatives. The nature and contribution of solvent-solute interactions on the emission properties were analyzed on the basis of solvatochromic shift data using Onsager's reaction field model, Reichardt's empirical solvent polarity scale ET(30), as well as Kamlet-Abboud-Taft's empirical solvent index. The studies revealed that all ESIPT tautomers emit from a moderately polarized excited-state whose dipole moment is not strongly influenced by the donor-attachment position. Furthermore, the negative solvatochromic shift behavior was most pronounced in protic solvents presumably due to specific hydrogen-bonding interactions. The extrapolated gas-phase emission energies correlated qualitatively well with the trends in Stokes shifts, suggesting that solute-solvent interactions do not play a significant role in explaining the divergent emission energy shifts. Detailed quantum chemical calculations not only confirmed the moderately polarized nature of the ESIPT tautomers but also provided a rational for the observed emission shifts based on the differential change in the HOMO and LUMO energies. The results gained from this study should provide guidelines for tuning the emission properties of this class of ESIPT fluorophores with potential applications in analytical chemistry, biochemistry, or materials science.
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http://dx.doi.org/10.1021/jp068832sDOI Listing
May 2007

Extended squaraine dyes with large two-photon absorption cross-sections.

J Am Chem Soc 2006 Nov;128(45):14444-5

School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.

Extended bis(donor)-substituted squaraine chromophores exhibit very high two-photon cross-sections (as high as 33 000 GM) in the near-IR; these can be attributed to the combination of large transition dipoles with small detuning energies. The modulus of the third-order nonlinear optical susceptibility at 1.3 mum has been found to be 7.0 x 10-11 esu for one of these chromophores.
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http://dx.doi.org/10.1021/ja065556mDOI Listing
November 2006

Excited-state properties and emission spectra of nonplanar heterocyclic helicenes.

J Phys Chem A 2006 Sep;110(38):11018-24

School of Chemistry and Biochemistry, Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30322-440, USA.

We discuss the electron-vibration coupling in mono-aza-[5]helicenes on the basis of a Franck-Condon analysis and density functional theory (DFT) calculations of the fluorescence and phosphorescence spectra measured in ethanol. The geometries of the initial states were obtained from time-dependent DFT (S(1)) and unrestricted DFT (T(1)) excited-state optimizations. In general, the position of the nitrogen atom has only a minor impact on the vibronic fine-structure in both absorption and emission. The shapes of the emission spectra from the lowest singlet and triplet states are found to be determined by contributions from multiple normal modes. The results of the calculations demonstrate how the interplay among these normal modes results in qualitatively and quantitatively different spectra for fluorescence and phosphorescence.
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http://dx.doi.org/10.1021/jp0616258DOI Listing
September 2006

Hint2, a mitochondrial apoptotic sensitizer down-regulated in hepatocellular carcinoma.

Gastroenterology 2006 Jun;130(7):2179-88

Institute for Clinical Pharmacology, University of Bern, Bern, Switzerland.

Background & Aims: Hints, histidine triad nucleotide-binding proteins, are adenosine monophosphate-lysine hydrolases of uncertain biological function. Here we report the characterization of human Hint2.

Methods: Tissue distribution was determined by real-time quantitative polymerase chain reaction and immunoblotting, cellular localization by immunocytochemistry, and transfection with green fluorescent protein constructs. Enzymatic activities for protein kinase C and adenosine phosphoramidase in the presence of Hint2 were measured. HepG2 cell lines with Hint2 overexpressed or knocked down were established. Apoptosis was assessed by immunoblotting for caspases and by flow cytometry. Tumor growth was measured in SCID mice. Expression in human tumors was investigated by microarrays.

Results: Hint2 was predominantly expressed in liver and pancreas. Hint2 was localized in mitochondria. Hint2 hydrolyzed adenosine monophosphate linked to an amino group (AMP-pNA; k(cat):0.0223 s(-1); Km:128 micromol/L). Exposed to apoptotic stress, fewer HepG2 cells overexpressing Hint2 remained viable (32.2 +/- 0.6% vs 57.7 +/- 4.6%), and more cells displayed changes of the mitochondrial membrane potential (87.8 +/- 2.35 vs 49.7 +/- 1.6%) with more cleaved caspases than control cells. The opposite was observed in HepG2 cells with knockdown expression of Hint2. Subcutaneous injection of HepG2 cells overexpressing Hint2 in SCID mice resulted in smaller tumors (0.32 +/- 0.13 g vs 0.85 +/- 0.35 g). Microarray analyses revealed that HINT2 messenger RNA is downregulated in hepatocellular carcinomas (-0.42 +/- 0.58 log2 vs -0.11 +/- 0.28 log2). Low abundance of HINT2 messenger RNA was associated with poor survival.

Conclusion: Hint2 defines a novel class of mitochondrial apoptotic sensitizers down-regulated in hepatocellular carcinoma.
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http://dx.doi.org/10.1053/j.gastro.2006.03.024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2569837PMC
June 2006

Activation of CREB by tauroursodeoxycholic acid protects cholangiocytes from apoptosis induced by mTOR inhibition.

Hepatology 2005 Jun;41(6):1241-51

Department of Clinical Pharmacology, University of Bern, Switzerland.

Tauroursodeoxycholic acid (TUDCA) is a cytoprotective bile acid frequently prescribed to patients with cholestatic diseases. Several mechanisms of action have been investigated, but the possibility that cyclic adenosine monophosphate responsive element binding protein (CREB), a transcription factor promoting cell survival, mediates TUDCA's protective effects has not been considered. We examined whether TUDCA activates CREB and whether this activation can protect biliary epithelial cells. Cholangiocytes were stressed by exposure to CCI-779, which inhibits signaling though the kinase mTOR (mammalian target of rapamycin), resulting in cell cycle arrest and apoptosis. Incubation of normal rat cholangiocytes (NRC) cells, with TUDCA resulted in phosphorylation of CREB (Western blotting analysis) and activation of CREB transcription activity (luciferase reporter assay). Inhibition of calcium signals and inhibition of protein kinase C prevented the TUDCA-induced activation of CREB. CCI-779 decreased the viability of rat cholangiocytes in a dose-dependent manner (MTT [3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay). TUDCA protected against CCI-779 cytotoxicity. A dominant negative form of CREB was stably transduced in NRC cells (NRC-M1). TUDCA protection was decreased in NRC-M1. While CCI-779 induced apoptosis in NRC cells as determined by caspase 3 activity, TUDCA attenuated CCI-779-induced apoptosis, an effect absent in NRC-M1. Finally, CCI-779 blocked proliferation of both NRC and NRC-M1 (thymidine incorporation) and this was unaffected by TUDCA. In conclusion, TUDCA activates CREB in cholangiocytes, reducing the apoptotic effect of CCI-779. These findings suggest a novel cytoprotective mechanism for this bile acid.
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http://dx.doi.org/10.1002/hep.20697DOI Listing
June 2005

Reconstruction of the lower eyelid by third eyelid lateral advancement and local transposition cutaneous flap after "en bloc" resection of squamous cell carcinoma in 5 cats.

Vet Surg 2005 Jan-Feb;34(1):78-82

Clinica Veterinaria STRADA OVEST, Treviso, Italy.

Objective: To describe a novel technique for blepharoplasty to cover a tissue defect involving >/=50% of the lower eyelid.

Study Design: Prospective clinical study.

Animals: Five cats with lower eyelid squamous cell carcinoma (SCC).

Methods: En bloc resection of SCC by removing >/=50% of the lower lid with either the medial or lateral canthus was performed without other adjunctive treatment for SCC. The lid defect was reconstructed with a transposition skin flap derived from the frontal (medial defect) or temporal (lateral defect) region. The third eyelid was advanced laterally without dissection from its insertion; its outer conjunctival layer was removed, and the skin flap was sutured with single interrupted sutures dorsally over the nictitating membrane, ventrally to the cutaneous edge of the surgical wound and medially or laterally (depending on the canthus removed) to the skin of the remaining lower lid.

Results: Satisfactory cosmetic and functional results were achieved and the Schirmer tear tests were normal. In 2 cats, the skin flap needed monthly hair trimming to avoid corneal lesions.

Conclusions: After en bloc resection of SCC involving >/=50% of the lower eyelid, reconstruction can be achieved by relocation of the third eyelid and use of a cutaneous transposition flap sutured to the scarified external surface of the third eyelid. Eyelid apposition and lacrimal function were preserved.

Clinical Relevance: Blepharoplasty using a cutaneous transposition flap sutured to the scarified surface of a relocated third eyelid should be considered for reconstruction of lower eyelid defects with >/=50% tissue loss of the lid margin.
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http://dx.doi.org/10.1111/j.1532-950X.2005.00014.xDOI Listing
August 2005