Publications by authors named "Reinhard Schmidt"

32 Publications

Epidemiology, treatment and outcome after compartment syndrome of the thigh in 69 cases - Experiences from a level I trauma centre.

Injury 2019 Jun 5;50(6):1242-1246. Epub 2019 Apr 5.

Medical University of Vienna, Department of Orthopaedics and Trauma Surgery, Waehringer Guertel 18-20, A-1090, Vienna, Austria. Electronic address:

Background: Compartment syndrome of the thigh (CST) is a rare condition, and its delayed diagnosis and therapy may lead to devastating adverse effects. Thus, the aim of this study was to present the amassed clinical experiences, regarding diagnosis and treatment of CST at a level I trauma centre.

Materials And Methods: The database was reviewed for all patients with a manifest CST treated surgically between 1995 and 2014.

Results: 69 patients (61 males and 8 females) met the inclusion criteria, with a mean age of 42.9 years (range: 11-87 years). Forty-four patients (64%) presented with an isolated CST. There was a significant association between complication rates and high impact vs. blunt trauma (12/32, 38% vs. 0/20, 0%; p = 0.0022; Fisher's exact test). The number of surgeries in patients with a concomitant femur fracture was significantly increased (in mean: 2.8 vs. 4.9 surgical interventions; p < 0.001; U test).

Conclusion: Patients after high impact trauma showed the highest complication rate. Concomitant femur fractures were associated with an increased number of surgical interventions. The synopsis of trauma mechanism, clinical presentation, age, anticoagulation status and clinical experience of the trauma surgeon seem to be the best tools to correctly diagnose CST.
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http://dx.doi.org/10.1016/j.injury.2019.04.001DOI Listing
June 2019

Post-operative retransfusion of unwashed filtered shed blood reduces allogenic blood demand in hip hemiarthroplasty in traumatic femoral neck fractures-a prospective randomized trial.

Int Orthop 2016 Dec 1;40(12):2575-2579. Epub 2016 Mar 1.

Department for Trauma Surgery, Medical University Vienna, Vienna, Austria.

Purpose: Patients who undergo hip hemiarthroplasty (HHA) due to traumatic femoral neck fracture frequently require red blood cell (RBC) transfusion. Although post-operative autologous blood transfusion (ABT) is well established in elective arthroplasty, its role in trauma patients remains unclear.

Methods: Two hundred twenty-nine patients with a traumatic femoral neck fracture that underwent HHA at our level-I trauma centre between 2005 and 2009 were prospectively randomized to a high-vacuum drainage or an ABT device. In this single-institution analysis, the number of RBC units as well as the amount of retransfused shed blood were recorded and compared according to study groups. Additionally, the significance of confounding factors for allogenic blood demand such as age, gender, pre-operative Hb level, surgical approach, type of prosthesis and amount of intra-operative RBC units were evaluated using multivariate analysis.

Results: One hundred thirty-five patients were randomized in the high-vacuum group while 94 patients received an ABT device. Intention to treat analysis revealed no significant difference in post-operative RBC demand (ABT: 0.87 RBC, high-vacuum drainage: 1.01 RBC; P = 0.374). However, patients that actually received retransfusion (N = 35) had a reduced post-operative RBC demand (0.49 RBC units, P = 0.014).

Conclusion: While only one third of trauma patients treated with an ABT device during HHA actually receive retransfusion, retransfused patients seem to significantly benefit from this treatment as reflected by a reduced pos-toperative RBC demand.
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http://dx.doi.org/10.1007/s00264-016-3143-1DOI Listing
December 2016

Ecotype variability in growth and secondary metabolite profile in Moringa oleifera: impact of sulfur and water availability.

J Agric Food Chem 2015 Mar 12;63(11):2852-61. Epub 2015 Mar 12.

⊥Julius Kühn Institute, Federal Research Centre for Cultivated Plants, Institute for Ecological Chemistry, Plant Analysis and Stored Product Protection, Königin-Luise-Str. 19, 14195 Berlin, Germany.

Moringa oleifera is widely cultivated in plantations in the tropics and subtropics. Previous cultivation studies with M. oleifera focused primarily only on leaf yield. In the present study, the content of potentially health-promoting secondary metabolites (glucosinolates, phenolic acids, and flavonoids) were also investigated. Six different ecotypes were grown under similar environmental conditions to identify phenotypic differences that can be traced back to the genotype. The ecotypes TOT4880 (origin USA) and TOT7267 (origin India) were identified as having the best growth performance and highest secondary metabolite production, making them an ideal health-promoting food crop. Furthermore, optimal cultivation conditions-exemplarily on sulfur fertilization and water availability-for achieving high leaf and secondary metabolite yields were investigated for M. oleifera. In general, plant biomass and height decreased under water deficiency compared to normal cultivation conditions, whereas the glucosinolate content increased. The effects depended to a great extent on the ecotype.
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http://dx.doi.org/10.1021/jf506174vDOI Listing
March 2015

Description of basic mining legal principles.

Authors:
Reinhard Schmidt

Adv Biochem Eng Biotechnol 2014 ;142:169-95

Technical University Bergakademie Freiberg, Institut für Bergbau und Spezialtiefbau, Freiberg, Germany,

The Federal Mining Act manages access, via the system of mining concessions, to areas free for mining natural resources that do not belong to the surface property and deposits' owner. These cover especially important natural resources for the economy, including coal, ore, salt, crude oil and natural gas, and also terrestrial heat. For mining operations there exist, however, the same decrees for natural resources in the property of the surface owners, which are predominantly higher-value industrial minerals such as roofing slate, basalt, quartz sand, and clays for the fireproofing industry. In the case of mining laws, administrative procedures such as issuing mining concessions, approving operating plans, and issuing permits or licenses to explore according to water rights or the Federal Immission Control Act, those authorities and departments in whose remit the projects fall are dealt with by the Mining Authority. This means that the Mining Authority is the only state point of contact for the applicant, essentially an "all-in-one" service as it will itself instigate any further participation procedures required. The classic licensing procedure of mining is the operations plan procedure, whereby the operator submits an operating plan to the Mining Authority, which then examines it to ensure it fulfills mandatory legal safety objectives. If necessary these safety objectives can be met during licensing of the operating plans by stipulating additional requirements, Depending on the subject and validity period there are overall operating plans having the widest possible remit with comprehensive participation by the authorities and basic operating plans that form the basis for every mining works. There are also special operating plans, which owing to the dynamics of mining, resolve matters that suddenly become necessary or when the basic operating plans as originally conceived were not relevant. The closing-down operating plan is the designated tool for closing down works and for the rehabilitation of the land; in the case of underground mining and mine boreholes an operating history must also be submitted. For those projects that have a significant effect on the environment, an obligatory overall operations plan with mining law project approval procedure and integrated Environmental Risk Assessment (UVP) are necessary. The point at which this is required is stipulated in the UVP-mining decree, for example if the mining area of an open-cast pit is more than 25 ha. Alongside the UVP, the procedure is also equipped with public participation and through its "concentrating effect" replaces further licensing procedures according to other laws. The Mining Authority combines supervision and licensing, which are usually inseparable due to the operations plan procedure, as well as aspects of occupational safety and of the protection of the environment. In view of this administrative concentration these should not be fragmented. The "all-in-one" service meets the requirements of a modern public-oriented administration, has only a few points of contact, and can therefore work efficiently.
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http://dx.doi.org/10.1007/10_2013_197DOI Listing
January 2015

Photochemistry and photophysics of the endoperoxide of mesodiphenylhelianthrene: a contribution to the localization of the S1(π*σ*) state of aromatic endoperoxides.

Authors:
Reinhard Schmidt

Photochem Photobiol Sci 2012 Jun 13;11(6):1004-9. Epub 2012 Feb 13.

Institut für Physikalische und Theoretische Chemie, J. W. Goethe-Universität, Max-von-Laue-Str. 7, D60438 Frankfurt am Main, Germany.

The endoperoxide of mesodiphenylhelianthrene MDHPO has been studied in detail with respect to fluorescence and photo-induced rearrangement. MDHPO proved to be non-fluorescent, although its absorption spectrum is dominated at the low energy side by a strong ππ* band with a maximum at 429.5 nm. Irradiation of that band effects rearrangement to the corresponding diepoxide MDHDO, a reaction typical for S(1)(π*σ*) excited endoperoxides (EPOs). The absorption spectrum of the product MDHDO is blue shifted by only 3.5 nm. MDHDO has the same extended planar aromatic system like its precursor MDHPO, but MDHDO fluoresces strongly. These results set the excitation energy of the S(1)(π*σ*) state of MDHPO to ≤23 000 cm(-1), which is considered to be a generally realistic value of the S(1)(π*σ*) state energy of aromatic EPOs. The main reaction of S(1)(π*σ*) excited MDHPO is, however, chemical deactivation to ground state MDHPO via an oxygen biradical. The sequence of O-O bond opening and closing is the general way of repopulation of the S(0) state of aromatic EPOs from S(1)(π*σ*) excited states.
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http://dx.doi.org/10.1039/c2pp05382aDOI Listing
June 2012

Where is the distal fracture line location of dorsally displaced distal radius fractures?

J Orthop Res 2011 Apr 26;29(4):489-94. Epub 2010 Oct 26.

Department of Trauma Surgery, Medical University of Vienna,Vienna, Austria.

No consensus currently exists on the facture location of dorsally displaced distal radius fractures (DRFs). We present a systematic evaluation of the distal fracture line (DFL) location of DRFs and possible influencing factors. Determining the average location of DRFs provides a basis for developing more sensitive tests to determine bone strength using a variety of imaging techniques and for developing improved biomechanical models to test fracture characteristics and surgical implants. Initial radiographs of 157 DRFs dorsally displaced DRFs in patients aged 40-74 years were identified, patient and trauma specific data were collected, and standard radiographic measurements and (AO) fracture classification were performed. The dorsal and palmar DFL locations relative to the corresponding apex of the lunate facet were measured. The DFL was located dorsally 7.9 ± 2.7 mm and palmarly 11.7 ± 3.9 mm proximal to the corresponding lunate fossa apex. The dorsal DFL was significantly distal to the palmar one (p  < 0.001), but the two did not correlate (r² = 0.018, p = 0.095). DFL location was independent of age, energy of the fall, and fracture complexity.
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http://dx.doi.org/10.1002/jor.21268DOI Listing
April 2011

[8-[Bis(carboxymethyl)aminomethyl]-6-bromo-7-hydroxycoumarin-4-yl]methyl moieties as photoremovable protecting groups for compounds with COOH, NH2, OH, and C=O functions.

J Org Chem 2010 May;75(9):2790-7

Leibniz-Institut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany.

We introduce a variant of coumarin-based photoactivatable protecting groups and use it exemplarily for caging of a carboxylic acid, an amine, a phenol, and a carbonyl compound. The caged compounds are efficiently photolyzed at long-wavelength UV/vis irradiation. Compared to the corresponding (6-bromo-7-hydroxycoumarin-4-yl)methyl (Bhc) derivatives, the novel coumarin-type caged compounds are distinguished by (i) dramatically increased solubilities in aqueous buffers, (ii) lower pK(a) values of the C7 hydroxyl of the coumarin chromophore, thus permitting efficient photorelease at lower pH, and (iii) higher photolysis quantum yields in the case of photoprotected carbonyl compounds. The primary step of the photocleavages occurs with rate constants of about 10(9) s(-1).
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http://dx.doi.org/10.1021/jo100368wDOI Listing
May 2010

Safety evaluation for a cell-based immune support system in an ex vivo rat model of gram-negative sepsis.

Ther Apher Dial 2009 Oct;13(5):444-50

Department of Anesthesiology and Intensive Care Medicine, University of Rostock, Germany.

Granulocyte dysfunction is a central component of immunodeficiency in septic patients. Granulocyte transfusions appear to be pathophysiologically useful; however, they cause unwanted side-effects in the lungs and other organs. This study evaluates the safety of an extracorporeal immune support system with granulocytic cells in a rat model of Gram-negative sepsis. Three groups of male CD rats received either saline (control group, I), a dose of Escherichia coli O7:K1 lethal to 90% of the animals (LD90) (septic group, II), or an LD90 dose of E. coli that was incubated with the human promyelocytic leukemia cell line (HL-60) (differentiated into the granulocytic direction) for 20 min prior to infusion (second septic group, III). The animals were observed for seven days. Pre-treatment with HL-60 cells resulted in no adverse effects in the group III animals. Significantly lower bacterial counts and endotoxin levels in the plasma were detected after 24 h as compared to group II (P < 0.05). Group III animals had better weight gain and more stable hemodynamics than group II animals (P < 0.01). Seven day survival was 0/8 in group II, 6/8 in group III, and 8/9 in group I (log-rank test: II-III: P < 0.001). The data suggest that extracorporeal use of granulocytes allows the therapeutic use of these cells while avoiding unwanted effects resulting from direct contact to internal organs.
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http://dx.doi.org/10.1111/j.1744-9987.2009.00764.xDOI Listing
October 2009

Biocompatibility assessment of peritoneal dialysis solutions with a new in vitro model of preconditioned human HL60 cells.

Artif Organs 2009 Jul;33(7):544-50

Department of Nephrology, Internal Medicine, University of Rostock, Rostock, Germany.

The purposes of this study were to test the human promyelocytic cell line HL60 for its usability as a new cell model for the immune barrier of the peritoneum, and to investigate the impact of different peritoneal dialysis (PD) solutions in the model. HL60 cells were stimulated by retinoic acid and recombinant human granulocyte and macrophage colony-stimulating factor to differentiate into neutrophilic granulocytes. Cells were incubated in different commercially available PD solutions. After a 4-h incubation, functional (chemiluminescence phagocytosis) and viability tests (Live-Dead, XTT) were performed. High glucose concentrations (>1.36%) and low pH values (<7.0) appeared to be detrimental for neutrophil functions and for neutrophil viability. There is a quantitative correlation between glucose concentration and the cytotoxicity of standard PD solutions (PD 1.36% glucose shows 42.6% higher chemiluminescence than PD 3.86% glucose [P < 0.05]). PD solution containing icodextrin shows 74.3% higher chemiluminescence than PD 3.86% glucose, and PD solution with amino acids shows 52.4% higher chemiluminescence than PD 3.86% glucose which is a sign for better biocompatibility in these tests (P < 0.05). The test system is useful for biocompatibility investigations of PD solutions and their effect on immune cells, for example, neutrophil granulocytes. It does not depend on donor variability and availability in comparison to models based on primary isolated leukocytes.
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http://dx.doi.org/10.1111/j.1525-1594.2009.00735.xDOI Listing
July 2009

Short-term growth hormone treatment and microcirculation: effects in patients with chronic kidney disease.

Microvasc Res 2009 Sep 3;78(2):246-52. Epub 2009 Jun 3.

Department of Pediatrics, University Children's Hospital, Rembrandtstrasse 16/17, 18057 Rostock, Germany.

Endothelial dysfunction is common in patients with chronic kidney disease (CKD) and contributes significantly to the high long-term cardiovascular morbidity and mortality. The short-term cardiovascular effects of recombinant human growth hormone (rhGH) in CKD patients (stages III-V) and healthy controls (n=15 each) were explored in a single-center, non-randomized pilot study. Subjects were investigated before, after a 7 day treatment with rhGH, and after a 7 day wash-out period. Microcirculation was assessed by nailfold capillaroscopy and leg strain gauge plethysmography. Echocardiography was performed and serum concentrations of IGF-I and IGF-binding protein-3 (IGFBP-3) were determined. Before the start of rhGH therapy, mean post-ischemic maximum flow velocity of erythrocytes (V(RBC)) and leg blood flow (LBF) in CKD patients were significantly reduced to 68% and 75% of that seen in controls, whereas V(RBC) and LBF under resting conditions were comparable. Treatment with rhGH significantly increased V(RBC) and LBF under resting conditions. Whereas maximum post-ischemic V(RBC) was improved by rhGH in patients and controls, maximum post-ischemic LBF increased in controls only. This was paralleled by a non-significant reduction of total vascular resistance, and increased heart rate and cardiac index. In conclusion, CKD patients respond to short-term rhGH treatment with significantly improved capillary blood flow, whereas only minor effects on total peripheral resistance and cardiac output were noted.
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http://dx.doi.org/10.1016/j.mvr.2009.05.006DOI Listing
September 2009

Caged progesterone: a new tool for studying rapid nongenomic actions of progesterone.

J Am Chem Soc 2009 Mar;131(11):4027-30

Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany.

Ketalization of the biomolecule progesterone with (6-bromo-7-hydroxycoumarin-4-yl)ethane-1,2-diol gives the photolabile progesterone derivatives 3 and 4. These compounds display dramatically reduced bioactivity and release progesterone upon irradiation with UV/vis or IR light. In particular, 4 can be used to perform concentration-jump experiments with high temporal and spatial resolution that allows one to study elegantly the mechanisms of rapid nongenomic cellular events evoked by progesterone. The usefulness of 4 was demonstrated by measurement of changes in swimming behavior of single human sperm caused by progesterone-induced Ca(2+) influx in the sperm flagellum.
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http://dx.doi.org/10.1021/ja808334fDOI Listing
March 2009

Extracorporeal cell therapy with granulocytes in a pig model of Gram-positive sepsis.

Crit Care Med 2009 Feb;37(2):606-13

Department of Anesthesiology and Intensive Care Medicine, Medical Faculty of the University of Rostock, Rostock, Germany.

Objectives: Granulocyte transfusions have been used to treat immune cell dysfunction in sepsis. As granulocyte transfusions can trigger tissue injury via local effects of neutrophils, we hypothesized that extracorporeal treatment of plasma using granulocytes would prove beneficial while having less side effects.

Design: Prospective controlled three-armed animal study.

Setting: Research laboratory.

Subjects: Twenty-one female immature pigs (7.5-12 kg, 7-9 weeks old).

Interventions: Three groups of spontaneously breathing, sedated pigs (n = 7 each) received an intravenous lethal dose of live Staphylococcus aureus over 1 hour. Although group I had no specific treatment (control), group II and III were subsequently treated for 4 hours with an extracorporeal device containing either no cells (sham control, group II) or human cell line-derived granulocytic cells (group III). Survival time and physiologic, biochemical, and hematologic parameters were monitored for 7 days.

Measurements And Main Results: All animals of group I died during the observation time (mean survival time: 70 hours). In group II, two of seven and in group III, six of seven animals survived the observation time (mean survival: 75 and 168 hours, respectively). Survival differences were significant between group I and III (p < 0.001) and between group II and III (p < 0.05) but not between group I and II (p = 0.43). Furthermore, group differences in bacterial blood concentrations, differential blood count, blood gases, lactate, and interleukins were observed. The extracorporeal cell treatment was well tolerated by the animals.

Conclusions: Extracorporeal therapy with granulocytic cells significantly improved survival in a pig model of sepsis. Further studies with this approach are encouraged.
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http://dx.doi.org/10.1097/CCM.0b013e318194aa77DOI Listing
February 2009

Improvement of impaired albumin binding capacity in acute-on-chronic liver failure by albumin dialysis.

Liver Transpl 2008 Sep;14(9):1333-9

Department of Internal Medicine, Division of Nephrology, University Rostock, Rostock, Germany.

Extracorporeal albumin dialysis (ECAD) enables the elimination of albumin bound substances and is used as artificial liver support system. Albumin binding function for the benzodiazepine binding site specific marker Dansylsarcosine was estimated in plasma samples of 22 patients with cirrhosis and hyperbilirubinaemia (ECAD: n = 12; control: n = 10) during a period of 30 days in a randomized controlled clinical ECAD trial. Albumin Binding Capacity (ABiC) at baseline was reduced to 31.8% (median; range 24%-74%) and correlated to the severity of liver disease. Within two weeks a significant improvement of ABiC and a reduction of the albumin bound markers bilirubin and bile acids were observed in the ECAD group. During single treatments a significant decrease of albumin bound substances (bilirubin and bile acids) as well as an increase in ABiC was observed. In the control group, baseline ABiC was significantly lower in patients who died during study period (34.2% vs. 41.7%; P < 0.028), whereas no significant differences were observed for CHILD, coagulation factors, albumin, bile acids nor bilirubin. At baseline 13 patients had a severely impaired ABiC (<40%), improvement of ABiC was more frequent in the ECAD group (5/6) than in the SMT group (2/7). Reduced albumin binding function is present in decompensated liver failure and is related to severity and 30 day survival. ABiC can be improved by ECAD. The beneficial effect of this treatment may be related to the improvement of albumin binding function more than to the elimination of specific substances. Characterization of albumin function by the ABiC test may help to evaluate different liver support systems and other therapeutic measures.
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http://dx.doi.org/10.1002/lt.21504DOI Listing
September 2008

Acupuncture of specific points influences cortical auditory evoked potentials--a volunteer crossover study.

Acupunct Electrother Res 2008 ;33(1-2):1-8

Department of Surgery, Military Hospital of Berlin, Germany.

Specificity of acupoints remains a crucial question in acupuncture research. The aim was to investigate whether acupuncture of specific points influences the Cortical Auditory Evoked Potentials (CAEP). Ten healthy volunteers were enrolled in this study according to inclusion criteria. One of 4 acupoints: TH3, GB43 (both claimed as specific for auditory system by Traditional Chinese Medicine) and non-specific points H7 and ST44, was stimulated during one session. Each volunteer received 4 sessions of acupuncture with an interval of 1 week between the sessions. The latencies and amplitudes of CAEP were registered before and after the acupuncture during each session. The mean peak latencies of P2 component decreased after stimulation of TH3 by 11 ms and GB43 by 14 ms whereas the peak latencies of N2 component increased after stimulation of TH3 by 9 ms and GB43 by 4 ms compared to baseline values (p<0.05). The stimulation of H7 and ST44 did not produce any changes. These findings confirm the specificity of acupuncture points TH3 and GB43 in relation to auditory system.
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http://dx.doi.org/10.3727/036012908803861177DOI Listing
November 2008

Mechanism of photocleavage of (coumarin-4-yl)methyl esters.

J Phys Chem A 2007 Jul 12;111(26):5768-74. Epub 2007 Jun 12.

Institute of Physical and Theoretical Chemistry, J. W. Goethe-University, Max-von-Laue-Strasse 7, D60438 Frankfurt am Main, Germany.

(Coumarin-4-yl)methyl esters (CM-A) are caged compounds that, upon excitation, release the masked biologically active acid HA and the highly fluorescent (coumarin-4-yl)methyl alcohol CM-OH very rapidly and in part with high efficiency. The results of photostationary and time-resolved investigations of 25 CM-A esters and corresponding CM-OH alcohols with varying substitution on the (coumarin-4-yl)methyl moiety and a wide variation in the structure of the acidic part have been analyzed. The initial step of the photoreaction is heterolytic ester cleavage leading to the singlet ion pair 1[CM+ A-] with rate constant k1. 1[CM+ A-] hydrolyzes to CM-OH and HA with rate constant k2 or recombines to ground-state CM-A with rate constant krec. 1[CM+ A-] is the key intermediate of the reaction. Stabilization of both CM+ by using electron-donating substituents and A- by increasing the acid strength leads to a strong enhancement of k1 and simultaneously to a diminution of krec. Therefore, stabilization of the ion pair has a two-fold positive effect on the photocleavage of (coumarin-4-yl)methyl esters: increasing the rate of the initial reaction step, which might require less than 30 ps, and increasing the efficiency of product formation.
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http://dx.doi.org/10.1021/jp071521cDOI Listing
July 2007

Mechanism of quenching by oxygen of the excited states of ruthenium(II) complexes in aqueous media. Solvent isotope effect and photosensitized generation of singlet oxygen, O2(1Deltag), by [Ru(diimine)(CN)4]2- complex ions.

Dalton Trans 2007 Jun 23(24):2517-27. Epub 2007 May 23.

Department of Chemistry, Faculty of Science, Ain Shams University, 11566, Abbassia, Cairo, Egypt.

In this study we report on the photophysical properties of some [RuL(CN)4](2-) complex ions where L = 2,2'-bipyridine (bpy), 5,5'-dimethyl-2,2'-bipyridine (dmb), 1,10-phenanthroline (phen), 1-ethyl-2-(2-pyridyl)benzimidazole (pbe), 2,2':6',2'''-terpyridine (tpy) and [RuL3](2+) where L = bpy or phen. Measurements were carried out in H2O and D2O. The effect of the deuterium isotope effect on the lifetime of these complexes is discussed. It has also been found that the presence of cyano groups has a pronounced effect on the lifetime of the excited metal-to-ligand charge transfer ((3)MLCT) of these complexes. Quenching of the (3)MLCT states by oxygen is reported in H2O and D2O. The rate constants, k(q), for quenching of the (3)MLCT states of these ruthenium complex ions by molecular oxygen are in the range (2.55 to 7.01) x 10(9) M(-1) s(-1) in H2O and (3.38 to 5.69) x 10(9) M(-1) s(-1) in D2O. The efficiency of singlet oxygen, O2((1)Delta(g)), production as a result of the (3)MLCT quenching by oxygen, f(Delta)(T), is reported in D2O and found to be in the range 0.29-0.52. The rate constants, k(q)(Delta), for quenching of singlet oxygen by ground state sensitizers in D2O is also reported and found to be in the range (0.15 to 3.46) x 10(7) M(-1) s(-1). The rate constants and the efficiency of singlet oxygen formation are quantitatively reproduced by a model that assumes the competition of a non-charge transfer (nCT) and a CT deactivation channel. nCT deactivation occurs from a fully established spin-statistical equilibrium of (1)(T1(3)Sigma) and (3)(T1(3)Sigma) encounter complexes by internal conversion (IC) to lower excited complexes that dissociate to yield O2((1)Delta(g)), and O2((3)Sigmag-). The balance between CT and nCT deactivation channels which is described by the relative contribution p(CT) of CT induced deactivation is discussed. The kinetic model proposed for the quenching of pi-pi* triplet states by oxygen can also be applied to the quenching of (3)MLCT states by oxygen.
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http://dx.doi.org/10.1039/b704895eDOI Listing
June 2007

On the effect of 1,4-diazabicyclo[2.2.2]octane on the singlet-oxygen dimol emission: photosensitized generation of (1O2)2.

J Phys Chem A 2007 May 25;111(20):4274-9. Epub 2007 Apr 25.

Institute of Organic Chemistry, Ufa Scientific Center of the RAS, 71 Prospect Oktyabrya, 450054 Ufa, Russia.

Time-resolved singlet-oxygen dimol luminescence has been recorded upon laser-pulsed photosensitization of singlet oxygen by 2-acetonaphthone or 1-H-phenalen-1-one in perfluorobenzene, perdeuterobenzene, and perdeuteroacetonitrile. It is shown that 1,4-diazabicyclo[2.2.2]octane (DABCO) does not enhance radiative properties of the dimol species generated by the photosensitization. Instead, DABCO strongly reduces the singlet-oxygen dimol luminescence. Rate constants for the quenching of the dimol luminescence by DABCO have been determined for the three solvents used.
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http://dx.doi.org/10.1021/jp070630oDOI Listing
May 2007

On the effect of 1,4-diazabicyclo[2.2.2]octane on the singlet-oxygen dimol emission: chemical generation of 1O2)2 in peroxide reactions.

J Phys Chem A 2007 May 25;111(20):4267-73. Epub 2007 Apr 25.

Institute of Organic Chemistry, Ufa Scientific Center of the RAS, 71 Prospect Oktyabrya, 450054 Ufa, Russia.

The acetone-catalyzed decomposition of monoperoxysulfate ions, the molybdate ion-induced decay of hydrogen peroxide, and the reactions of N-chlorosuccinimide or N-bromosuccinimide with hydrogen peroxide and of dimethyldioxirane with tertiary amines as well as the thermal decomposition of 1,4-dimethylnaphthalene endoperoxide lead to the chemiluminescence of singlet-oxygen dimol species (1O2)2 emitting at 634 and 703 nm. In contrast to the expected enhancement of (1O2)2 chemiluminescence upon addition of 1,4-diazabicyclo[2.2.2]octane (DABCO) [Deneke, C.F.; Krinsky, N. I. J. Am. Chem. Soc. 1976, 98, 3041. Di Mascio, P.; Sies, H. J. Am. Chem. Soc. 1989, 111, 2909.], quenching has been observed. Our data show that enhancement of singlet-oxygen dimol chemiluminescence is not a general phenomenon and, consequently, DABCO is not a reliable chemiluminescent probe for the presence of (1O2)2 in chemical and biochemical systems.
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http://dx.doi.org/10.1021/jp070629pDOI Listing
May 2007

Albumin-binding function is reduced in patients with decompensated cirrhosis and correlates inversely with severity of liver disease assessed by model for end-stage liver disease.

Eur J Gastroenterol Hepatol 2007 Mar;19(3):257-63

Division of Nephrology, Department of Internal Medicine, University Rostock, Rostock, Germany.

Background: Human serum albumin has multiple functions, the most important being maintaining colloid osmotic pressure, ligand binding and transport. In liver failure, an impaired binding of endogenous substances and drugs can be observed. The aim of this study was to investigate the relationship between the severity of liver disease and an impaired albumin binding.

Methods: In 44 patients with decompensated liver cirrhosis, Child-Turcotte-Pugh and model for end-stage liver disease scores were assessed and the site II-specific albumin-binding function (albumin-binding capacity) was characterized. Briefly, the unbound amount of diazepam site ligand Dansylsarcosine in a sample was determined and compared with the unbound amount in a reference albumin solution (=100%).

Results: Thirty-two out of 44 of the patients presented with Child-Turcotte-Pugh class C, the median Child-Turcotte-Pugh score was 10 [6-13 (min-max)], median model for end-stage liver disease score was 21 (8-40) and the median albumin-binding capacity was 63 (24-91)% compared with healthy controls 98 (95-106)% (P<0.001). Albumin-binding capacity was found to be strongly correlated to model for end-stage liver disease (r=0.783; P<0.001).

Conclusions: An impaired albumin-binding function of a site II-specific marker in decompensated liver cirrhosis was found to be correlated to the severity of the liver disease.
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http://dx.doi.org/10.1097/MEG.0b013e3280101f7dDOI Listing
March 2007

Kinetics study of the photocleavage of (coumarin-4-yl)methyl esters.

J Phys Chem A 2005 Jun;109(23):5000-4

Institute of Physical and Theoretical Chemistry, J. W. Goethe-University, Marie-Curie-Str. 11, D60439 Frankfurt am Main, Germany.

Photolabile coumarinylmethyl esters of biomolecules (caged compounds) are new tools for studying spatial and time-dependent aspects of signal transduction in living cells. Herein we describe a fluoresence spectroscopic method for the determination of the rate constants of the photolysis steps of such caged compounds using (6.7-dimethoxycoumarin-4-yl)methyl diethyl phosphate (DMCM-DEP) and sodium (6,7-dimethoxycoumarin-4-yl)methyl sulfate (DMCM-S). DMCM-DEP and DMCM-S are caged compounds which photorelease a proton, the corresponding acid anion, and the strongly fluorescent alcohol DMCM-OH upon excitation. The results of stationary and time-resolved measurements of the photochemistry and the luminescence of both caged compounds indicate that DMCM-OH is produced already during the excitation pulse. The quantitative analysis of the data demonstrates that the first step of the reaction--heterolytic bond cleavage of the coumarinylmethyl ester leading to the ion pair of a DMCM cation and an acid anion--is very fast with a rate constant of k1 approximately 2 x 10(10) s(-1). Recombination of the ion pair occurs with a rate constant of k(rec) approximately 2.3 x 10(9) s(-1) and is about 10 times faster than the competing hydrolysis reaction of the DMCM cation yielding DMCM-OH and a proton. Thus, both caged compounds belong to the fastest phototriggers known.
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http://dx.doi.org/10.1021/jp050581kDOI Listing
June 2005

Comment on "quenching mechanism of rose bengal triplet state involved in photosensitization of oxygen in ethylene glycol".

Authors:
Reinhard Schmidt

J Phys Chem A 2006 Jun;110(24):7749

Institut für Physikalische und Theoretische Chemie, J. W. Goethe-Universität, Max-von-Laue-Strasse 7, D60438 Frankfurt am Main, Germany.

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http://dx.doi.org/10.1021/jp060819kDOI Listing
June 2006

Photosensitized generation of singlet oxygen.

Authors:
Reinhard Schmidt

Photochem Photobiol 2006 Sep-Oct;82(5):1161-77

Institut für Physikalische und Theoretische Chemie, J. W. Goethe-Universität, Max-von-Laue-Strasse 7, D60438 Frankfurt am Main, Germany.

This work gives an overview of what is currently known about the mechanisms of the photosensitized production of singlet oxygen. Quenching of pi pi* excited triplet states by O2 proceeds via internal conversion of excited encounter complexes and exciplexes of sensitizer and O2. Both deactivation channels lead with different efficiencies to singlet oxygen generation. The balance between the deactivation channels depends on the triplet-state energy and oxidation potential of the sensitizer, and on the solvent polarity. A model has been developed that reproduces rate constants and efficiencies of the competing processes quantitatively. Sensitization by excited singlet states is much more complex and hence only qualitative rules could be elaborated, despite serious efforts of many groups. However, the most important deactivation paths of fluorescence quenching by O2 are again directed by excess energies and charge-transfer interactions similar to triplet-state quenching by O2. Finally, two recent developments in photosensitization of singlet oxygen are reviewed: Two-photon sensitizers with particular application potential for photodynamic therapy and fluorescence imaging of biological samples and singlet oxygen sensitization by nanocrystalline porous silicon, a material with very different photophysics compared to molecular sensitizers.
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http://dx.doi.org/10.1562/2006-03-03-IR-833DOI Listing
May 2007

The effect of solvent polarity on the balance between charge transfer and non-charge transfer pathways in the sensitization of singlet oxygen by pipi triplet states.

Authors:
Reinhard Schmidt

J Phys Chem A 2006 May;110(18):5990-7

Institut für Physikalische und Theoretische Chemie, J. W. Goethe-Universität, Marie-Curie-Str. 11, D60439 Frankfurt am Main, Germany.

A large set of literature kinetic data on triplet (T(1)) sensitization of singlet oxygen by two series of biphenyl and naphthalene sensitizers in solvents of strongly different polarity has been analyzed. The rate constants and the efficiencies of singlet oxygen formation are quantitatively reproduced by a model that assumes the competition of a non-charge transfer (nCT) and a CT deactivation channel. nCT deactivation occurs from a fully established spin-statistical equilibrium of (1)(T(1)(3)Sigma) and (3)(T(1)(3)Sigma) encounter complexes by internal conversion (IC) to lower excited complexes that dissociate to yield O(2)((1)Sigma(g)(+)), O(2)((1)Delta(g)), and O(2)((3)Sigma(g)(-)). IC of (1,3)(T(1)(3)Sigma) encounter complexes is controlled by an energy gap law that is generally valid for the transfer of electronic energy to and from O(2). (1,3)(T(1)(3)Sigma) nCT complexes form in competition to IC (1)(T(1)(3)Sigma) and (3)(T(1)(3)Sigma) exciplexes if CT interactions between T(1) and O(2) are important. The rate constants of exciplex formation depend via a Marcus type parabolic model on the corresponding free energy change DeltaG(CT), which varies with sensitizer triplet energy, oxidation potential, and solvent polarity. O(2)((1)Sigma(g)(+)), O(2)((1)Delta(g)), and O(2)((3)Sigma(g)(-)) are formed in the product ratio (1/6):(1/12):(3/4) in the CT deactivation channel. The balance between nCT and CT deactivation is described by the relative contribution p(CT) of CT induced deactivation calculated for a sensitizer of known triplet energy from its quenching rate constant. It is shown how the change of p(CT) influences the quenching rate constant and the efficiency of singlet oxygen formation in both series of sensitizers. p(CT) is sensitive to differences of solvent polarity and varies for the biphenyls and the naphthalenes as sigmoidal with DeltaG(CT). This quantitative model represents a realistic and general mechanism for the quenching of pipi triplet states by O(2), surpassing previous advanced models.
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http://dx.doi.org/10.1021/jp060017pDOI Listing
May 2006

Quantitative determination of 1sigma(g)+ and 1delta(g) singlet oxygen in solvents of very different polarity. General energy gap law for rate constants of electronic energy transfer to and from O2 in the absence of charge transfer interactions.

Authors:
Reinhard Schmidt

J Phys Chem A 2006 Mar;110(8):2622-8

Institut für Physikalische und Theoretische Chemie, J. W. Goethe-Universität, Marie-Curie-Str.11, D60439 Frankfurt am Main, Germany.

The quenching of excited triplet states of sufficient energy by O2 leads to O2(1sigma(g)+) and O2(1delta(g)) singlet oxygen and O2(3sigma(g)-) ground-state oxygen as well. The present work investigates the question whether in the absence of charge transfer (CT) interactions between triplet sensitizer and O2 the rate constants of formation of the three different O2 product states follow a generally valid energy gap law. For that purpose, lifetimes of the upper excited O2(1sigma(g)+) have been determined in a mixture of 7 vol % benzene in carbon tetrachloride, in chloroform, and in perdeuterated acetonitrile. They amount to 1.86, 1.40, and 0.58 ns, respectively. Furthermore, rate constants of O2(1sigma(g)+), O2(1delta(g)), and O2(3sigma(g)-) formation have been measured in these three solvents for five pi pi* triplet sensitizers with negligible CT interactions. The rate constants are independent of solvent polarity. After normalization for the multiplicity of the respective O2 product state, the rate constants follow a common dependence on the excess energies of the respective product channels. This empirical energy gap relation describes also quantitatively the rate constants of quenching of O2(1delta(g)) by 28 carotenoids. Therefore, it represents in the absence of CT interactions a generally valid energy gap law for the rate constants of electronic energy transfer to and from O2.
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http://dx.doi.org/10.1021/jp0568172DOI Listing
March 2006

A multi-center quality control study of different CA15-3 immunoassays.

Clin Lab 2005 ;51(11-12):641-5

Krankenhaus Dresden-Friedrichstadt, Institut für Klinische Chemie und Labormedizin, Dresden, Germany.

A long-term multi-center quality control study of CA15-3 determinations based on measurements of liquid BIOREF CA15-3 control sera was conducted in 17 participating laboratories. Seven different CA15-3 assays were applied using the appropriate automatic immunoanalyzers. CA15-3 means were determined for BIOREF low, medium and high level control sera. Values were 19.3 +/- 2.7 kU/l, 75.2 +/- 11.4 kU/l and 162.9 +/- 37.1 kU/l, respectively. Inter-assay imprecisions were calculated for each of the controls for each laboratory and for each of the methods, with coefficients of variation (CV) ranging from 2.9-15.5%. As a means of evaluation of assay linearity concentration ratios (high/medium, medium/low, high/low) were calculated and found to be in good agreement with reference values throughout the study. Individual long-term time courses of CA15-3 control measurements provided evidence for variability of test results due to changes in assay calibration. Comparisons with CV data obtained with BIOREF controls 17 years ago demonstrate significant improvements of CA15-3 assay precision in recent years. In conclusion, test-independent reference material can be used for CA15-3 quality control and in particular enables applicants to check for long-term stability of CA15-3 assay performance.
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June 2006

The balance between charge transfer and non-charge transfer pathways in the sensitization of singlet oxygen by pi pi* triplet states.

Authors:
Reinhard Schmidt

Photochem Photobiol Sci 2005 Jun 21;4(6):481-6. Epub 2005 Apr 21.

Institut für Physikalische und Theoretische Chemie, Johann Wolfgang Goethe-Universität, D60439 Frankfurt am Main, Germany.

A charge transfer (CT) channel and a non-CT deactivation channel, both leading to formation of O(2)((1)Sigma (g)(+)), O(2)((1) Delta(g)) and O(2)((3)Sigma(g)(-)), compete in the quenching of triplet states by O(2). Recent studies by our group demonstrated that these channels are described by rather simple and general quantitative relations. In the present paper we use the detailed kinetic data on the quenching by O(2) of pi pi* triplet sensitizers of three homologous aromatic series in CCl(4) to derive a parameter, which describes the balance between CT and non-CT deactivation. This quantity, p(CT), is the relative contribution of CT mediated deactivation and is easily calculated for a sensitizer of known triplet energy from its quenching rate constant. The parameter p(CT) quantitatively describes the balance between both deactivation channels without requiring any knowledge of oxidation potentials. It is shown how the variation of p(CT) influences the efficiencies and the rate constants of O(2)((1)Sigma(g)(+)), O(2)((1)Delta(g)) and O(2)((3)Sigma(g)(-)) formation in the quenching process.
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http://dx.doi.org/10.1039/b502735gDOI Listing
June 2005

Autoimmune-associated congenital heart block: treatment of the mother with immunoadsorption.

Ther Apher Dial 2005 Apr;9(2):148-53

Department of Nephrology, University of Rostock, Rostock, Germany.

Autoimmune-associated congenital heart block (CHB) is a rare complication of pregnancy in mothers with Anti-Ro/SSA antibodies (SSA-abs), resulting in fetal myocarditis, atrioventricular block, hydrops fetalis and/or intrauterine fetal death. As these antibodies are supposed to be directly involved in the pathogenesis of CHB, their removal should be associated with an improved clinical course. Extracorporeal immunoadsorption (IA) is the most efficient method to remove IgG-immunoglobulins like SSA-abs selectively. Two women with high titers of those auto-antibodies [mothers serum 615 and 612, respectively (normal range <3.0 IU/mL)] were treated with IA two to three times per gestation week in the outpatient department of the University of Rostock. In both patients, the mean removal of IgG (65 +/- 6%) to a target near 2.0 g/L after IA was successful. The SSA-abs were reduced from mean 328 +/- 138 and 247 +/- 105 pre IA to 88 +/- 124 and 98 +/- 42 post IA, respectively. One child received a pacemaker due to the persisting atrioventricular block grade III after birth. The second was unaffected. The removal of highly elevated SSA-antibodies by immunoadsorption is a possible treatment option in pregnant woman with high titers of those antibodies and/or a positive history of clinical complications. Further clinical studies are necessary.
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http://dx.doi.org/10.1111/j.1774-9987.2005.00226.xDOI Listing
April 2005

Reversible binding of oxygen to aromatic compounds.

Acc Chem Res 2003 Sep;36(9):668-75

Laboratoire d'Oxydation et de Formulation, LCOM, UMR CNRS 8009, ENSCL, BP 108, F-59652 Villeneuve d'Ascq Cedex, France.

Many polycyclic aromatic hydrocarbons are able to trap singlet oxygen (1)O(2). Some of the endoperoxides, thus obtained, exhibit the exceptional feature of releasing oxygen, frequently in the excited singlet state, under heating or UV irradiation. In this Account, we provide a short summary of the present knowledge on these endoperoxides: preparation and thermal and photolytic decomposition, with a special emphasis on the structural requirements to favor cycloreversion. The profitable use of this property in the development of highly reversible photochromic systems and of specific sources or traps of (1)O(2) in aqueous media is also described.
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http://dx.doi.org/10.1021/ar010086gDOI Listing
September 2003
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