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Schmieder F, Schmieder S, Eger R, Friedrich S, Werner A, Danz N, Marx U, Sonntag F. Automated universal chip platform for fluorescence based cellular assays. BIOMED ENG-BIOMED TE 2012. [DOI: 10.1515/bmt-2012-4319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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May PC, Dean RA, Lowe SL, Martenyi F, Sheehan SM, Boggs LN, Monk SA, Mathes BM, Mergott DJ, Watson BM, Stout SL, Timm DE, Smith LaBell E, Gonzales CR, Nakano M, Jhee SS, Yen M, Ereshefsky L, Lindstrom TD, Calligaro DO, Cocke PJ, Greg Hall D, Friedrich S, Citron M, Audia JE. Robust central reduction of amyloid-β in humans with an orally available, non-peptidic β-secretase inhibitor. J Neurosci 2011; 31:16507-16. [PMID: 22090477 PMCID: PMC6633289 DOI: 10.1523/jneurosci.3647-11.2011] [Citation(s) in RCA: 288] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2011] [Revised: 09/01/2011] [Accepted: 09/09/2011] [Indexed: 01/02/2023] Open
Abstract
According to the amyloid cascade hypothesis, cerebral deposition of amyloid-β peptide (Aβ) is critical for Alzheimer's disease (AD) pathogenesis. Aβ generation is initiated when β-secretase (BACE1) cleaves the amyloid precursor protein. For more than a decade, BACE1 has been a prime target for designing drugs to prevent or treat AD. However, development of such agents has turned out to be extremely challenging, with major hurdles in cell penetration, oral bioavailability/metabolic clearance, and brain access. Using a fragment-based chemistry strategy, we have generated LY2811376 [(S)-4-(2,4-difluoro-5-pyrimidin-5-yl-phenyl)-4-methyl-5,6-dihydro-4H-[1,3]thiazin-2-ylamine], the first orally available non-peptidic BACE1 inhibitor that produces profound Aβ-lowering effects in animals. The biomarker changes obtained in preclinical animal models translate into man at doses of LY2811376 that were safe and well tolerated in healthy volunteers. Prominent and long-lasting Aβ reductions in lumbar CSF were measured after oral dosing of 30 or 90 mg of LY2811376. This represents the first translation of BACE1-driven biomarker changes in CNS from preclinical animal models to man. Because of toxicology findings identified in longer-term preclinical studies, this compound is no longer progressing in clinical development. However, BACE1 remains a viable target because the adverse effects reported here were recapitulated in LY2811376-treated BACE1 KO mice and thus are unrelated to BACE1 inhibition. The magnitude and duration of central Aβ reduction obtainable with BACE1 inhibition positions this protease as a tractable small-molecule target through which to test the amyloid hypothesis in man.
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Stegbauer J, Potthoff SA, Quack I, Mergia E, Clasen T, Friedrich S, Vonend O, Woznowski M, Königshausen E, Sellin L, Rump LC. Chronic treatment with angiotensin-(1-7) improves renal endothelial dysfunction in apolipoproteinE-deficient mice. Br J Pharmacol 2011; 163:974-83. [PMID: 21371005 DOI: 10.1111/j.1476-5381.2011.01295.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND AND PURPOSE ApolipoproteinE-deficient [apoE (-/-)] mice, a model of human atherosclerosis, develop endothelial dysfunction caused by decreased levels of nitric oxide (NO). The endogenous peptide, angiotensin-(1-7) [Ang-(1-7)], acting through its specific GPCR, the Mas receptor, has endothelium-dependent vasodilator properties. Here we have investigated if chronic treatment with Ang-(1-7) improved endothelial dysfunction in apoE (-/-) mice. EXPERIMENTAL APPROACH ApoE (-/-) mice fed on a lipid-rich Western diet were divided into three groups and treated via osmotic minipumps with either saline, Ang-(1-7) (82 µg·kg(-1) ·h(-1) ) or the same dose of Ang-(1-7) together with D-Ala-Ang-(1-7) (125 µg·kg(-1) ·h(-1) ) for 6 weeks. Renal vascular function was assessed in isolated perfused kidneys. KEY RESULTS Ang-(1-7)-treated apoE (-/-) mice showed improved renal endothelium-dependent vasorelaxation induced by carbachol and increased renal basal cGMP production, compared with untreated apoE (-/-) mice. Tempol, a reactive oxygen species (ROS) scavenger, improved endothelium-dependent vasorelaxation in kidneys of saline-treated apoE (-/-) mice whereas no effect was observed in Ang-(1-7)-treated mice. Chronic treatment with D-Ala-Ang-(1-7), a specific Mas receptor antagonist, abolished the beneficial effects of Ang-(1-7) on endothelium-dependent vasorelaxation. Renal endothelium-independent vasorelaxation showed no differences between treated and untreated mice. ROS production and expression levels of the NAD(P)H oxidase subunits gp91phox and p47phox were reduced in isolated preglomerular arterioles of Ang-(1-7)-treated mice, compared with untreated mice, whereas eNOS expression was increased. CONCLUSION AND IMPLICATIONS Chronic infusion of Ang-(1-7) improved renal endothelial function via Mas receptors, in an experimental model of human cardiovascular disease, by increasing levels of endogenous NO.
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Willis BA, Zhang W, Ayan-Oshodi M, Lowe SL, Annes WF, Sirois PJ, Friedrich S, de la Peña A. Semagacestat pharmacokinetics are not significantly affected by formulation, food, or time of dosing in healthy participants. J Clin Pharmacol 2011; 52:904-13. [PMID: 21724950 DOI: 10.1177/0091270011407195] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Semagacestat, a γ-secretase inhibitor, reduces formation of amyloid beta peptide. Two single-dose (140 mg), open-label, randomized, 3-period, crossover studies evaluated the effect of formulation, food, and time of dosing on the pharmacokinetics and pharmacodynamics of semagacestat in healthy participants. The first study (n = 14) compared tablet to capsules. For all formulations, the median time to maximum plasma concentration (t(max)) was generally 1.0 hour. Plasma elimination was rapid, with a half-life of approximately 2.5 hours. Tablet form II bioavailability (F) relative to capsule was approximately 100% (F = 1.03 [90% confidence interval (CI), 0.96-1.10]). In the second study, participants (n = 27) received semagacestat either fed or fasting in the morning or fasting in the evening. No significant change in exposure (AUC(0-∞) [area under the concentration-time curve from 0 to infinity] ratio = 1.02, [90% CI, 0.990-1.05]) occurred with food, whereas maximum plasma concentration (C(max)) declined approximately 15%, and median t(max) was delayed to 1.5 hours. Time of dosing made no significant difference in AUC(0-∞), C(max), or t(max) (AUC(0-∞) ratio 1.01, [90% CI, 0.975-1.04]). No clinically significant safety concerns occurred in either study. Accordingly, semagacestat may be dosed without regard to formulation, food, or time of administration.
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Bard F, Fox M, Friedrich S, Kinney G, Yednock T. P4‐406: Unique brain PK properties of 3D6 and bapineuzumab depend on cerebral amyloid load in PDAPP transgenic mice. Alzheimers Dement 2011. [DOI: 10.1016/j.jalz.2011.09.220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Moertl MG, Friedrich S, Kraschl J, Wadsack C, Lang U, Schlembach D. Haemodynamic effects of carbetocin and oxytocin given as intravenous bolus on women undergoing caesarean delivery: a randomised trial. BJOG 2011; 118:1349-56. [DOI: 10.1111/j.1471-0528.2011.03022.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Yong GJ, Kolagani RM, Adhikari S, Drury OB, Gardner C, Bionta RM, Friedrich S. Heteroepitaxy of Nd(0.67)Sr(0.33)MnO3 on silicon for bolometric x-ray detector application. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:113906. [PMID: 21133485 DOI: 10.1063/1.3499244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We have recently reported the design concept and sensor fabrication for a novel bolometric x-ray detector based on a rare earth manganite material for application as a total energy monitor for the Linac Coherent Light Source (LCLS) free electron laser at the Stanford Linear Accelerator Center (SLAC). The detector employs epitaxial thin films of Nd(0.67)Sr(0.33)MnO(3) grown on Si by pulsed laser deposition. In this paper we report details of the fabrication of the actual detector, its response characteristics under photon illumination from LCLS, and improvements in the growth scheme of the sensor material on Si using a buffer/template layer scheme that employs yttria-stabilized zirconia, cerium oxide (CeO(2)), and bismuth titanate (Bi(4)Ti(3)O(12)). The thermal sensor response changes linearly with the energy of an optical calibration laser as expected, and the signals from optical and x-ray pulses at LCLS are very similar, thereby validating the design concept. To the best of our knowledge, the LCLS detector application reported here is the first practical use of colossal magnetoresistive manganite bolometers.
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Martenyi F, Lowe S, Dean RA, Monk SA, Gonzales CR, Friedrich S, May PC, Audia JE, Citron M, LaBell ES, Moran S, Yen M, Jhee S, Kam J, Ereshefsky L. P4‐088: Central and Peripheral Pharmacokinetic and Pharmacodynamic Effects of the β‐site APP Cleavage Enzyme (BACE1) Inhibitor LY2811376 In Humans. Alzheimers Dement 2010. [DOI: 10.1016/j.jalz.2010.08.148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Adolf S, Millonig G, Friedrich S, Seitz HK, Mueller S. Valsalva and orthostatic maneuvers increase liver stiffness (Fibroscan®) in healthy volunteers. ZEITSCHRIFT FUR GASTROENTEROLOGIE 2010. [DOI: 10.1055/s-0029-1246547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Beyschlag W, Hanisch S, Friedrich S, Jentsch A, Werner C. 15N natural abundance during early and late succession in a middle-European dry acidic grassland. PLANT BIOLOGY (STUTTGART, GERMANY) 2009; 11:713-24. [PMID: 19689779 DOI: 10.1111/j.1438-8677.2008.00173.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
delta(15)N and total nitrogen content of above- and belowground tissues of 13 plant species from two successional stages (open pioneer community and ruderal grass stage) of a dry acidic grassland in Southern Germany were analysed, in order to evaluate whether resource use partitioning by niche separation and N input by N(2)-fixing legumes are potential determinants for species coexistence and successional changes. Within each stage, plants from plots with different legume cover were compared. Soil inorganic N content, total plant biomass and delta(15)N values of bulk plant material were significantly lower in the pioneer stage than in the ruderal grass community. The observed delta(15)N differences were rather species- than site-specific. Within both stages, there were also species-specific differences in isotopic composition between above- and belowground plant dry matter. Species-specific delta(15)N signatures may theoretically be explained by (i) isotopic fractionation during microbial-mediated soil N transformations; (ii) isotopic fractionation during plant N uptake or fractionation during plant-mycorrhiza transfer processes; (iii) differences in metabolic pathways and isotopic fractionation within the plant; or (iv) partitioning of available N resources (or pools) among plant groups or differential use of the same resources by different species, which seems to be the most probable route in the present case. A significant influence of N(2)-fixing legumes on the N balance of the surrounding plant community was not detectable. This was confirmed by the results of an independent in situ removal experiment, showing that after 3 years there were no measurable differences in the frequency distribution between plots with and without N(2)-fixing legumes.
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Millonig G, Friedrich S, Adolf S, Pöschl G, Stiefel P, Seitz HK, Mueller S. Increased venous pressure increases liver stiffness (Fibroscan) independent of liver fibrosis. ZEITSCHRIFT FUR GASTROENTEROLOGIE 2009. [DOI: 10.1055/s-0029-1191981] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Yong GJ, Kolagani R, Adhikari S, Mundle RM, Cox DW, Davidson AL, Liang Y, Drury OB, Hau-Riege SP, Gardner C, Ables E, Bionta RM, Friedrich S. Colossal Magnetoresistive Manganite Based Fast Bolometric X-ray Sensors for Total Energy Measurements of Free Electron Lasers. ACTA ACUST UNITED AC 2008. [DOI: 10.1166/sl.2008.m151] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Mörtl M, Pickel K, Friedrich S, Ulrich D, Lang U, Schlembach D. Hemodynamic changes of carbetocin and oxytocin given as i.v. bolus on women undergoing Cesarean section. Geburtshilfe Frauenheilkd 2008. [DOI: 10.1055/s-0028-1088756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Siemers ER, Friedrich S, Dean RA, Sethuraman G, DeMattos R, Jennings D, Tamagnan G, Marek K, Seibyl J. P4-346: Safety, tolerability and biomarker effects of an Abeta monoclonal antibody administered to patients with Alzheimer's disease. Alzheimers Dement 2008. [DOI: 10.1016/j.jalz.2008.05.2416] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Ali S, Hau ID, Niedermayr TR, Friedrich S. Ultrahigh energy resolution gamma-ray spectrometers for precision measurements of uranium enrichment. J Radioanal Nucl Chem 2008. [DOI: 10.1007/s10967-008-0628-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Kaase M, Lenga S, Friedrich S, Szabados F, Sakinc T, Kleine B, Gatermann SG. Comparison of phenotypic methods for penicillinase detection in Staphylococcus aureus. Clin Microbiol Infect 2008; 14:614-6. [PMID: 18397333 DOI: 10.1111/j.1469-0691.2008.01997.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Penicillinase testing is required for Staphylococcus aureus isolates with a penicillin MIC of </=0.12 mg/L. This study compared five phenotypic assays with a PCR for blaZ when testing 197 S. aureus isolates. The starch-iodine plate method and nitrocefin tests had low sensitivities of 42.9% and 35.7%, respectively. The cloverleaf assay and the penicillin zone-edge determination method had sensitivities of 67.8% and 71.4%, respectively, and these methods might be appropriate in many circumstances, but were not as sensitive as blaZ PCR.
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Siemers ER, Dean RA, Friedrich S, Ferguson-Sells L, Gonzales C, Farlow MR, May PC. Safety, tolerability, and effects on plasma and cerebrospinal fluid amyloid-beta after inhibition of gamma-secretase. Clin Neuropharmacol 2008; 30:317-25. [PMID: 18090456 DOI: 10.1097/wnf.0b013e31805b7660] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES gamma-Secretase inhibitors may be useful as disease-modifying drugs for the treatment of Alzheimer disease. LY450139 is a gamma-secretase inhibitor currently in clinical development, with doses being optimized through the use of biomarkers. METHODS To further characterize biomarker responses to LY450139, single oral doses of 60, 100, or 140 mg were administered to volunteers without neuropsychiatric disease. Extensive safety assessments were obtained along with measures of changes in amyloid-beta (Abeta) in plasma and cerebrospinal fluid (CSF). A measure of the change in plasma Abeta1-40 was derived (area above the curve), which was determined by both the magnitude and duration of Abeta1-40 reduction. RESULTS A total of 31 subjects (ages 49-53 years, 19 men) were enrolled. With the possible exception of headache, no clinically significant adverse events or laboratory changes were observed. A dose-proportional increase in drug exposure was present in plasma and in CSF. A dose-dependent change in plasma Abeta1-40 area above the curve was also demonstrated. Using the 140-mg dose, a maximum 72.6% reduction in plasma Abeta1-40 was demonstrated that did not return to baseline for more than 12 hours. Cerebrospinal fluid concentrations of Abeta were unchanged 4 hours after drug administration. CONCLUSIONS These data show that single doses of LY450139 up to 140 mg are accompanied by a dose-dependent plasma Abeta response. No response in CSF Abeta was apparent 4 hours after dosing.
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Gatermann SG, Koschinski T, Friedrich S. Distribution and expression of macrolide resistance genes in coagulase-negative staphylococci. Clin Microbiol Infect 2007; 13:777-81. [PMID: 17501977 DOI: 10.1111/j.1469-0691.2007.01749.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In total, 494 isolates of coagulase-negative staphylococci (CoNS) were identified to the species level by biochemical tests and sodA sequencing. Erythromycin resistance phenotypes were determined and specific resistance genes were identified by PCR. The prevalence of erythromycin resistance varied widely among staphylococcal species, from 0% in Staphylococcus lugdunensis to almost 90% in Staphylococcus haemolyticus. Most (63%) erythromycin-resistant isolates carried constitutively expressed erm(C) as the sole resistance determinant, with the notable exception of Staphylococcus hominis subsp. hominis, which carried inducible erm(C). The erm(A) and erm(B) determinants were comparatively rare. The msr(A) gene was carried by 20-30% of all erythromycin-resistant isolates, with little variation among species, and was combined in 16.7% of isolates with mph(C), a resistance gene of unknown clinical relevance found previously in isolates of veterinary origin. No erythromycin resistance that could not be attributed to the genes investigated was detected. It was concluded that the presence of methylases cannot be assumed in CoNS isolates that appear erythromycin-resistant and clindamycin-susceptible; thus, methods that detect the export mechanism should be used with clinically significant isolates to indicate whether use of clindamycin may be effective. In Staphylococcus epidermidis and S. haemolyticus, 46% and 66%, respectively, of erythromycin-resistant, clindamycin-susceptible isolates were susceptible to clindamycin therapy.
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Chien JY, Friedrich S, Heathman MA, de Alwis DP, Sinha V. Pharmacokinetics/Pharmacodynamics and the stages of drug development: role of modeling and simulation. AAPS JOURNAL 2005; 7:E544-59. [PMID: 16353932 PMCID: PMC2751257 DOI: 10.1208/aapsj070355] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pharmacokinetic (PK) and pharmacodynamic (PD) modeling and simulation (M&S) are well-recognized powerful tools that enable effective implementation of the learn-and-confirm paradigm in drug development. The impact of PK/PD M&S on decision making and drug development risk management is dependent on the question being asked and on the availability and quality of data accessible at a particular stage of drug development. For instance, M&S methodologies can be used to capture uncertainty and use the expected variability in PK/PD data generated in preclinical species for projection of the plausible range of clinical dose; clinical trial simulation can be used to forecast the probability of achieving a target response in patients based on information obtained in early phases of development. Framing the right question and capturing the key assumptions are critical components of the "learn-and-confirm" paradigm in the drug development process and are essential to delivering high-value PK/PD M&S results. Selected works of PK/PD modeling and simulation from preclinical to phase III are presented as case examples in this article.
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Bongartz T, Härle P, Friedrich S, Karrer S, Vogt T, Seitz A, Müller-Ladner U. Successful treatment of psoriatic onycho-pachydermo periostitis (POPP) with adalimumab. ACTA ACUST UNITED AC 2005; 52:280-2. [PMID: 15641098 DOI: 10.1002/art.20763] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Psoriatic onycho-pachydermo periostitis (POPP) is recognized as a rare subset of psoriatic arthritis, characterized by psoriatic onychodystrophy, connective tissue thickening above the distal phalanx, and a periosteal reaction. Therapy for this rare disease is based on treatments used for psoriatic arthritis, but traditional disease-modifying antirheumatic drugs, such as sulfasalazine and methotrexate, have shown inconsistent and unsatisfactory results. We report herein a successful therapeutic approach for POPP using the fully human anti-tumor necrosis factor (TNF) antibody adalimumab in a 42-year-old male patient. After 4 months of anti-TNF treatment, a remarkable normalization of the clinical appearance was achieved and magnetic resonance imaging showed complete resolution of the initial inflammatory lesions. Therefore, we consider a TNF-blocking strategy as promising for treatment of POPP.
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Friedrich S, Brummer R, Wittern KP, Hochstein B. Dielectric spectroscopy of concentrated cosmetic W/O-emulsions: possibilities to distinguish product changes caused by coalescence, sedimentation and variation of ingredients. Int J Cosmet Sci 2004; 26:157-64. [DOI: 10.1111/j.1467-2494.2004.00215.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bîrsan T, Hausen B, Higgins JP, Hubble RW, Klupp J, Stalder M, Celniker A, Friedrich S, O'Hara RM, Morris RE. Treatment with humanized monoclonal antibodies against CD80 and CD86 combined with sirolimus prolongs renal allograft survival in cynomolgus monkeys. Transplantation 2003; 75:2106-13. [PMID: 12829920 DOI: 10.1097/01.tp.0000066806.10029.7a] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Co-stimulatory blockade has been shown to prolong allograft survival in different transplant models. We investigated the effect of combining humanized anti-CD80 and anti-CD86 monoclonal antibodies (mAb) with sirolimus in cynomolgus monkey renal transplant recipients. METHODS After renal transplantation, groups of four animals were treated daily with sirolimus, sirolimus and nine weekly doses of mAb, two weekly doses of mAb, or sirolimus and two weekly doses of mAb. RESULTS Survival was significantly better in monkeys treated with the combination of sirolimus and mAb when compared with treatment with either agent alone (P=0.0067 by log-rank analysis). When combined with sirolimus, nine weekly doses of mAb did not result in an additional survival benefit compared with only two mAb doses (P=0.74). None of the treatment regimens used in this study resulted in development of transplantation tolerance. CONCLUSIONS Sirolimus can be successfully combined with humanized mAb against CD80 and CD86. Induction with a short course of mAb is effective in prolonging allograft survival in combination with sirolimus.
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Folwaczny C, Wawarta R, Otto B, Friedrich S, Landgraf R, Riepl RL. Gastric emptying of solid and liquid meals in healthy controls compared with long-term type-1 diabetes mellitus under optimal glucose control. Exp Clin Endocrinol Diabetes 2003; 111:223-9. [PMID: 12845561 DOI: 10.1055/s-2003-40467] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND Neuropathy of the enteric nervous system and hyperglycaemia are regarded as the main causes of diabetic gastroparesis. PATIENTS AND METHODS In ten patients with Type-1 diabetes mellitus and sensomotoric neuropathy gastric emptying half times were compared with ten healthy controls by employing the 13C-octanoic acid and the 13C-sodiumacetate breath test, resp., following the intake of equally composed and isocaloric liquid and solid meals. Plasma glucose concentrations were controlled by permanent intravenous administration of insulin. RESULTS In diabetes mellitus gastric emptying half times after the intake of the liquid meal (p < 0.05) but not after ingestion of the solid meal were slightly prolonged. Gastric emptying half times in patients and controls were not different when liquid and solid meals were compared. CONCLUSIONS Acute hyperglycaemia appears to be more important than the neuropathy of the enteric nervous system in the pathophysiology of diabetic gastroparesis. The rate of gastric emptying is obviously not dependent on the phase of a meal, but rather on the composition and the caloric content.
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Specht T, Benninghoven D, Jantschek G, Ebeling A, Friedrich S, Kunzendorf S, Scheuer A, Jantschek I, Katus HA. [Psychosocial screening in coronary heart disease: 5 decisive questions]. ZEITSCHRIFT FUR KARDIOLOGIE 2002; 91:458-65. [PMID: 12219693 DOI: 10.1007/s00392-002-0799-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
There is overwhelming convincing evidence linking psychosocial factors to outcome of patients with coronary heart disease. Thus, assessment of psychosocial variables should be an integrated part of risk stratification. To facilitate psychosocial assessment in clinical practice and to identify a subset of patients possibly benefitting from extended psychological measures, a new semistandardized interview instrument is presented, called LIPS ("Lübecker halbstandardisiertes Interview zum Psychosozialen Screening"). Beside the well-known and relevant domains social support, emotional stress/vital exhaustion, anxiety and depression, a score for the global psychosocial impairment can be documented. LIPS requires no specialized psychological training, its time requirement is five to ten minutes and it is easily integrated into routine physical and psychosocial assessment. The presentation includes the original instrument in addition to its validation on standardized self-administered questionnaires.
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Zhou H, Sequeira M, Goad ME, Erickson J, Wong A, Clark E, Dunussi-Joannopoulos K, Li RC, Friedrich S, Hayes LL, Wolf SF. Efficacy and mechanisms of action of rmB7.2-Ig as an antitumor agent in combination with Adriamycin and Cytoxan chemotherapy. Clin Immunol 2001; 101:303-14. [PMID: 11726223 DOI: 10.1006/clim.2001.5123] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The efficacy of chemotherapy for cancer is often limited by toxicity. Immune approaches to cancer immunotherapy, while promising for specificity and long-term protection, have not typically proven potent enough to generate significant therapeutic responses. We have shown therapeutic benefit using recombinant murine B7.2-Ig (rmB7.2-Ig) in murine tumor models. Efficacy was dependent on immune activity and was not associated with toxicity. Recently, the efficacy of rmB7.2-Ig was demonstrated in leukemia tumor models in combination with chemotherapeutic agents. To further explore the potential of this approach, we evaluated the efficacy in solid tumor models of rmB7.2-Ig given in combination with chemotherapeutics commonly used in clinical practice, testing the effects of dose and schedule. RmB7.2-Ig in combination with some chemotherapeutics enhances the activity and efficacy of reduced chemotherapeutic doses. However, the relative timing of chemotherapy and rmB7.2-Ig dosing can be important. Investigation of mechanisms of action based on histological studies suggests that inflammatory as well as T cell mechanisms comprise the response. Additional studies of mice deleted of B7.1, B7.2, and CTLA-4 suggest that the enhanced response induced by rmB7.2-Ig may not be mediated through CD28 ligation alone. The efficacy suggests potential for recombinant human B7.2-Ig as an adjuvant to chemotherapy in promoting immune-mediated mechanisms to augment the activity of chemotherapy.
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Hausen B, Klupp J, Christians U, Higgins JP, Baumgartner RE, Hook LE, Friedrich S, Celnicker A, Morris RE. Coadministration of either cyclosporine or steroids with humanized monoclonal antibodies against CD80 and CD86 successfully prolong allograft survival after life supporting renal transplantation in cynomolgus monkeys. Transplantation 2001; 72:1128-37. [PMID: 11579312 DOI: 10.1097/00007890-200109270-00025] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND Recent studies have shown some efficacy using monotherapy with monoclonal antibodies (mAb) against CD80 and CD86 receptors after life-supporting renal transplantation in non-human primates. Our study was designed to evaluate the efficacy of combinations of the same mAbs with either microemulsion cyclosporine (CsA) or steroids. METHODS Unilateral renal transplantation was performed in 16 blood group-matched and MLR-mismatched cynomolgus monkeys that were assigned to four different treatment groups. All monkeys in groups I, II, and IV were treated with the combination of a CD80 (h1F1) and CD86 (h3D1) mAb given at 20 mg/kg each preoperatively, then 5 mg/kg at weekly intervals starting postoperative (po) day 0 until poday 56 (9 doses). In group I the animals (n=4) were treated with mAbs only. In group II (n=4) mAbs were combined with a CsA regimen adjusted daily to maintain target 24 hr trough levels of 150-300 ng/ml CsA for poday 0 to poday 56. In group III (n=4) the animals received CsA monotherapy according to the same regimen as group II. In group IV methylprednisone was administered at 2 mg/kg IV on poday 0-2, then at 0.5 mg/kg/day prednisone per gavage that was and tapered to 0.2 mg/kg/day on which they were maintained until poday 56. All animals were off all immunosuppressive treatment after poday 56 and were then followed until poday 119. RESULTS The mean survival of groups I-IV was 74 (range 9-119 days), 113 (96-119 days), 39 (22-71 days), and 79 days (6 to 119), respectively. All animals in group I showed clinical evidence of acute severe rejection (fever, creatinine increase, anuria) within the first week posttransplant, including those that retained renal function until poday 119. Only one animal in group II had a moderate clinical rejection during the treatment period and three of four animals survived the intended follow-up period. All animals in group III had multiple biopsy proven or severe clinical rejection episodes within the first 21 days and only one animal survived beyond poday 40. Moderate or severe acute rejection was diagnosed in three of four animals of group IV within the first 28 days post transplant and only one animal survived until poday 119. CONCLUSION Our data show that combining a calcineurin inhibitor or prednisone with mAbs designed to block costimulatory signals does not antagonize the immunosuppressive efficacy of these mAbs. In addition, combining CsA with mAbs directed against the CD80 and CD86 receptors significantly prolongs graft survival when compared to CsA monotherapy. Therefore clinical trials of humanized mAbs to CD80 and CD86 used in combination with conventional immunosuppression can be considered.
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Tschöp M, Wawarta R, Riepl RL, Friedrich S, Bidlingmaier M, Landgraf R, Folwaczny C. Post-prandial decrease of circulating human ghrelin levels. J Endocrinol Invest 2001; 24:RC19-21. [PMID: 11434675 DOI: 10.1007/bf03351037] [Citation(s) in RCA: 443] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ghrelin, an endogenous ligand of the GH secretagogue-receptor, has recently been shown to stimulate GH secretion and to have orexigenic and adipogenic effects in rodents, but little is known about its regulation and biological function in humans. Gastric motor function is under control of the central nervous system; however, the afferent and efferent loops of this feedback control mechanism remain to be elucidated. In the study presented here we investigated the effect of nutrient intake on circulating human ghrelin levels, and a possible association between ghrelin levels and gastric emptying. Ten healthy volunteers received a standard meal after an overnight fast. Food intake significantly decreased plasma ghrelin levels from 248.5 +/- 15.0 to 179.5 +/- 17.9 fmol/ml (120 min after meal, p=0.047). Gastric emptying half-time (non-invasive 13C-octanoic acid breath test) was correlated with fasting plasma ghrelin levels (r=0.74, p=0.0013). Ghrelin appears to be one possible candidate to provide feedback signaling between nutrient intake, gastric motor function and the central nervous system.
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Preusse G, Friedrich S, Salzer R. Retention behavior of humic substances in reversed phase HPLC. FRESENIUS' JOURNAL OF ANALYTICAL CHEMISTRY 2000; 368:268-73. [PMID: 11220591 DOI: 10.1007/s002160000457] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Recovery as well as appearance and abundance (in percent) of different fractions of humic substances are found to depend on injected sample amounts in reversed phase HPLC. Sample amounts have been varied both by varying sample concentration and sample volume. In case of lowest amounts injected only two fractions were obtained for a commercial humic acid sodium salt, i.e. one for excluded molecules and one for hydrophobic components. The abundance of excluded molecules decreases upon increasing amounts injected. Another three fractions are obtained upon increasing amount injected: a hydrophilic fraction and two hydrophobic ones. This behavior is explained by auxiliary equilibria between excluded components and humic molecules previously adsorbed on the stationary phase.
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Drechsler M, Schumacher V, Friedrich S, Wildhardt G, Giesler S, Schroth A, Bodem J, Royer-Pokora B. Genomic structure, alternative transcripts and chromosome location of the human LIM domain binding protein 1 gene LDB1. CYTOGENETICS AND CELL GENETICS 2000; 87:119-24. [PMID: 10640831 DOI: 10.1159/000015377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
By protein interaction screening using a radioactive LMO2 protein probe we have isolated a LIM domain binding protein. The gene shows high homology to independently isolated genes from mouse, Xenopus and Drosophila called Ldb1/Nli/Clim-2, Xldb1 and Chip, respectively. The human and mouse genes differ by only two amino acids, suggesting that the gene that we have isolated is the human homologue. Here we describe the genomic organization, alternative transcript forms and the chromosome mapping of the human gene LDB1 (alias NLI). The gene is spread over at least 12 kb and has 11 exons. Preceding the described ATG initiation site in the mouse a highly conserved region between mouse, chicken and human was detected with a second possible in frame initiation site coding for further 36 amino acids. An alternative splice site adding six nucleotides corresponding to the addition of two amino acids at the end of exon 10 was found. The gene was mapped to chromosome 10q24-->q25 by in situ hybridization, a region frequently deleted in many types of cancer. Fine mapping with a radiation hybrid panel localized the gene in the interval between the markers D10S603 and D10S540.
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Krampfl K, Schlesinger F, Dengler R, Bufler J, Klaus K, Friedrich S, Reinhardt D. Pentobarbital has curare-like effects on adult-type nicotinic acetylcholine receptor channel currents. Anesth Analg 2000; 90:970-4. [PMID: 10735809 DOI: 10.1213/00000539-200004000-00036] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
UNLABELLED Pentobarbital (PB) is widely used as a short-term sedative and anticonvulsive drug with a side-effect of relaxing muscle tone. We investigated block of nicotinic acetylcholine receptor (nAChR) channel currents by PB using the patch-clamp technique in combination with an ultrafast system for solution exchange. As a preparation, recombinant rat adult-type nAChR channels transiently expressed in HEK293 cells were used. Appli-cation of 1 mM acetylcholine to small cells or outside-out patches showed a transient current with fast activation and desensitization kinetics. Adding PB to the acetylcholine-containing solution resulted in a decrease of the time constant of current decay and of the peak current amplitude starting at concentrations >0.01 mM PB. Preincubation of nAChR channels with PB led to a decrease of the peak current amplitude without alteration of activation and desensitization kinetics caused by competitive block of nAChR channels. In conclusion, similar to the effect of d-Tubocurarine, block of nAChR channel currents by PB can be explained by a combination of open-channel and competitive block. IMPLICATIONS The interaction between adult-type nicotinic acetylcholine receptors, acetylcholine, and pentobarbital was biophysically investigated by using the patch-clamp technique in combination with tools for ultrafast solution exchange. PB elicited open-channel block and competitive block of nicotinic acetylcholine receptor channel currents, whereas the latter seems to be effective in clinically relevant concentrations.
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Westmacott G, Zhong F, Frank M, Friedrich S, Labov SE, Benner WH. Investigating ion-surface collisions with a niobium superconducting tunnel junction detector in a time-of-flight mass spectrometer. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2000; 14:600-607. [PMID: 10775095 DOI: 10.1002/(sici)1097-0231(20000415)14:7<600::aid-rcm915>3.0.co;2-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The performance of an energy sensitive, niobium superconducting tunnel junction (STJ) detector is investigated by measuring the pulse height produced by impacting molecular and atomic ions at different kinetic energies. Ions are produced by laser desorption and matrix-assisted laser desorption in a time-of-flight mass spectrometer. Our results show that the STJ detector pulse height decreases for increasing molecular ion mass, passes through a minimum at around 2000 Da, and then increases with increasing mass of molecular ions above 2000 Da. The detector does not show a decline in sensitivity for high mass ions as is observed with microchannel plate ion detectors. These detector plus height measurements are discussed in terms of several physical mechanisms involved in an ion-surface collision.
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Winkler C, Dornfeld S, Dörr W, Friedrich S, Baumann M. Reirradiation after radiotherapy of primary brain tumors. FRONTIERS OF RADIATION THERAPY AND ONCOLOGY 1999; 33:276-83. [PMID: 10549497 DOI: 10.1159/000061208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
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Winkler C, Dornfeld S, Schwarz R, Friedrich S, Baumann M. [The results of radiotherapy in meningiomas with a high risk of recurrence. A retrospective analysis]. Strahlenther Onkol 1998; 174:624-8. [PMID: 9879349 DOI: 10.1007/bf03038510] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
AIM Retrospective assessment of the efficacy of radiation therapy for meningiomas with high risk for local recurrence. PATIENTS AND METHODS Records of 67 patients with meningiomas treated from 1974 to 1995 at 2 centres were analyzed. Follow-up time ranged from 0.8 to 213 months (median: 61 months). Radiation therapy was given either after local failure or after biopsy or subtotal resection. The ratio between malignant (n = 20) and benign (n = 47) meningioma was 1:2.4. Median age of the patients was 55 years (7 to 77 years). Radiation treatment was given at 1.5 to 2 Gy per fraction to 36 to 79.5 Gy. Survival rates were calculated by the Kaplan-Meier method. Statistical comparisons were performed with the log-rank test and the Cox proportional hazards model. The Bonferroni method was used to correct for multiple comparisons. RESULTS Five- and 10-year disease-free survival rates were 82% +/- 5% (standard error) and 70% +/- 9%. Local control rates at 5 and 10 years were 78% +/- 5% and 68% +/- 9%. In uni- and multivariate analysis histology, sex, total dose and center showed no significant influence on the results. Patients age was significant for local control (univariate p = 0.02; multivariate p = 0.03) and disease-free survival (univariate/multivariate p = 0.04). The postoperative tumor burden had a significant influence of disease-free survival (multivariate p = 0.04). After Bonferroni correction no significant influence was observed. We did not observe late side effects, especially brain necrosis. CONCLUSIONS Despite of the negative selection of our patients we observed high survival- and local control rates after radiation therapy. This underscores the role of radiation therapy in the treatment of meningiomas with high risk of local failure.
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Friedrich S, Mears CA, Nideröst B, Hiller LJ, Frank M, Labov SE, Barfknecht AT, Cramer SP. Superconducting Tunnel Junction Array Development for High-Resolution Energy-Dispersive X-ray Spectroscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 1998; 4:616-621. [PMID: 10087284 DOI: 10.1017/s143192769898059x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
: Cryogenic energy-dispersive X-ray detectors are being developed because of their superior energy resolution (10 eV FWHM for keV X-rays) compared to that achieved in semiconductor energy-dispersive spectrometry (EDS) systems. So far, their range of application is limited because of their comparably small size and low count rate. We present data on the development of superconducting tunnel junction (STJ) detector arrays to address both of these issues. A single STJ detector has a resolution of around 10 eV below 1 keV and can be operated at count rates of the order 10,000 counts/sec. We show that the simultaneous operation of several STJ detectors does not dimish their energy resolution significantly, and it increases the detector area and the maximum count rate by a factor given by the total number of independent channels.
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Rosenzweig M, DeMaria MA, Harper DM, Friedrich S, Jain RK, Johnson RP. Increased rates of CD4(+) and CD8(+) T lymphocyte turnover in simian immunodeficiency virus-infected macaques. Proc Natl Acad Sci U S A 1998; 95:6388-93. [PMID: 9600975 PMCID: PMC27734 DOI: 10.1073/pnas.95.11.6388] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Defining the rate at which T cells turn over has important implications for our understanding of T lymphocyte homeostasis and AIDS pathogenesis, yet little information on T cell turnover is available. We used the nucleoside analogue bromodeoxyuridine (BrdUrd) in combination with five-color flow cytometric analysis to evaluate T lymphocyte turnover rates in normal and simian immunodeficiency virus (SIV)-infected rhesus macaques. T cells in normal animals turned over at relatively rapid rates, with memory cells turning over more quickly than naive cells. In SIV-infected animals, the labeling and elimination rates of both CD4(+) and CD8(+) BrdUrd-labeled cells were increased by 2- to 3-fold as compared with normal controls. In normal and SIV-infected animals, the rates of CD4(+) T cell BrdUrd-labeling and decay were closely correlated with those of CD8(+) T cells. The elimination rate of BrdUrd-labeled cells was accelerated in both naive and memory T lymphocytes in SIV-infected animals. Our results provide direct evidence for increased rates of both CD4(+) and CD8(+) T cell turnover in AIDS virus infection and have important implications for our understanding of T cell homeostasis and the mechanisms responsible for CD4(+) T cell depletion in AIDS.
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Josenhans C, Friedrich S, Suerbaum S. Green fluorescent protein as a novel marker and reporter system in Helicobacter sp. FEMS Microbiol Lett 1998; 161:263-73. [PMID: 9570118 DOI: 10.1111/j.1574-6968.1998.tb12957.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
In order to be able to study gene regulation in single, live Helicobacter pylori bacteria in vitro or in contact with host cells, we established the green fluorescent protein gene gfp from Aequorea victoria as a reporter gene for use with Helicobacter species. We describe here the construction of genomic transcriptional fusions of the promoterless gfp gene with the flaA and flaB promoters of H. pylori. We have also constructed a Mini-Tn3-km-gfp transposon to be used for shuttle transposon mutagenesis in H. pylori and H. mustelae. A marker strain with wild-type phenotype, carrying multiple plasmid-borne copies of gfp under the control of the H. pylori flaB promoter, was constructed for studies of bacterial distribution and transmission in animal models.
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Friedrich S, Saville B, Cheng YL. Drug distribution in the vitreous humor of the human eye: the effects of aphakia and changes in retinal permeability and vitreous diffusivity. J Ocul Pharmacol Ther 1997; 13:445-59. [PMID: 9326726 DOI: 10.1089/jop.1997.13.445] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The majority of eyes that receive drug therapy exhibit some form of pathophysiological degradation. Two common pathophysiological states are retinal inflammation, which results in breakdown of the blood-retinal barrier, and aphakia. The purpose of this study was to examine the effects of aphakia and changes in retinal permeability and vitreous diffusivity on drug distribution in the vitreous humor of the human eye. The study was performed using a finite element model that accurately accounts for the vitreous geometry and boundary conditions. Intravitreal injection is the most common method for treating posterior segment disorders; therefore, this administration method was simulated using the models. Elimination from aphakic and phakic eyes was compared for four extreme injection locations and for two retinal permeabilities. When the retinal permeability was fixed at 5.0 x 10(-5) cm/s, increasing the drug diffusivity through the vitreous from 5.4 to 10(-7) to 2.4 x 10(-5) cm2/s decreased the half-life of drug from 64 hours to 2.7 hours. When the drug diffusivity was fixed at 5.6 x 10(-6) cm2/s, increasing the retinal permeability of the drug from 1.0 x 10(-7) to 1.0 x 10(-4) cm/s decreased the half-life of drug from 44 to 7 hours. Therefore, drug diffusivity and retinal permeability are key factors that influence elimination from the vitreous, and must be considered, particularly if the blood retinal barrier has been compromised. Faster drug elimination was observed in aphakic eyes than in phakic eyes, especially for drugs with a low retinal permeability and injected close to the lens capsule. Injection position is also important if the drug is injected in close proximity to a primary elimination barrier.
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Friedrich S, Cheng YL, Saville B. Drug distribution in the vitreous humor of the human eye: the effects of intravitreal injection position and volume. Curr Eye Res 1997; 16:663-9. [PMID: 9222083 DOI: 10.1076/ceyr.16.7.663.5061] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE The purpose of this study was to determine how the position and volume of an intravitreal injection affect the distribution and elimination of drug from the vitreous humor. METHODS A mathematical model that had been developed and used previously to study drug distribution in the vitreous humor of the rabbit eye was modified to match the physiology of the human eye. Fluorescein and fluorescein glucuronide were used as the model compounds for these studies. Four extreme injection locations were considered: a central injection, an injection displaced towards the retina, an injection displaced towards the lens, and an injection displaced toward the hyaloid membrane. Injections containing an equal mass of drug dissolved in volumes of either 15 microL or 100 microL were compared. RESULTS The location of an intravitreal injection was found to have a substantial effect on elimination and distribution in the vitreous. Peak concentrations at different vitreous locations varied by over three orders of magnitude, depending on the injection location. The mean concentration of drug remaining in the vitreous 24 hours after the intravitreal injection varied by up to a factor of 3.8, depending on the injection location. Changing the volume of the injection from 15 microL to 100 microL dampened the effects of the initial injection location; however, meant concentrations at 24 hours still varied by up to a factor of 2.5. CONCLUSIONS Careful control of the conditions of an intravitreal injection could reduce treatment variability, improve bioavailability, and reduce the possibility of retinal toxicity.
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Shannon RP, Friedrich S, Mathier M, Knight DR. Effects of renin inhibition compared to angiotensin converting enzyme inhibition in conscious dogs with pacing-induced heart failure. Cardiovasc Res 1997; 34:464-72. [PMID: 9231029 DOI: 10.1016/s0008-6363(97)00066-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
OBJECTIVE To compare the effects of angiotensin converting enzyme inhibition (ACEI) (captopril 1 mg/kg i.v.) to direct renin inhibition (CP80794 3 mg/kg i.v.) on left ventricular and systemic hemodynamics and peripheral blood flows in advanced congestive heart failure (CHF). METHODS Conscious chronically instrumented dogs (n = 14) were treated with captopril, 1 mg/kg, i.v., or CP80794, 3 mg/kg, i.v., before and after development of advanced CHF induced by 4-7 weeks of rapid ventricular pacing. After advanced CHF, comparisons between the inhibitors were made at equihypotensive doses. RESULTS In advanced CHF, both agents caused comparable reductions in mean arterial pressure (MAP) (-22% from 79 +/- 4 mmHg) and comparable increases (P < 0.01) in cardiac output (CP80794, 1.4 +/- 0.3 to 1.8 +/- 0.1 l/min; captopril, 1.4 +/- 0.1 to 1.9 +/- 0.1 l/min). Neither agent had a significant effect on LV contractility. In contrast, CP80794 caused a greater (P < 0.05) increase in renal blood flow (66 +/- 6% from 64 +/- 5 ml/min) compared to captopril (33 +/- 4% from 66 +/- 7 ml/min). CONCLUSIONS Renin inhibition with CP80794 and ACEI with captopril caused comparable hemodynamic effects in advanced CHF. However, CP80794 caused significantly greater increases in renal blood flow and suppressed renin activity to a greater degree than captopril.
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Friedrich S, Cheng YL, Saville B. Finite element modeling of drug distribution in the vitreous humor of the rabbit eye. Ann Biomed Eng 1997; 25:303-14. [PMID: 9084836 DOI: 10.1007/bf02648045] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Direct intravitreal injection of drug is a common method for treating diseases of the retina or vitreous. The stagnant nature of the vitreous humor and surrounding tissue barriers creates concentration gradients within the vitreous that must be accounted for when developing drug therapy. The objective of this research was to study drug distribution in the vitreous humor of the rabbit eye after an intravitreal injection, using a finite element model. Fluorescein and fluorescein glucuronide were selected as model compounds due to available experimental data. All required model parameters were known except for the permeability of these compounds through the retina, which was determined by fitting model predictions to experimental data. The location of the intravitreal injection in the experimental studies was not precisely known; therefore, several injection locations were considered, and best-fit retinal permeability was determined for each case. Retinal permeability of fluorescein and fluorescein glucuronide estimated by the model ranged from 1.94 x 10(-5) to 3.5 x 10(-5) cm s(-1) and from 0 to 7.62 x 10(-7) cm s(-1), respectively, depending on the assumed site of the injection. These permeability values were compared with values previously calculated from other models, and the limitations of the models are discussed. Intravitreal injection position was found to be an important variable that must be controlled in both experimental and clinical settings.
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Woelki G, Friedrich S, Hanschmann G, Salzer R. HPLC fractionation and structural dynamics of humic acids. ACTA ACUST UNITED AC 1997. [DOI: 10.1007/s002160050211] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Hard BC, Friedrich S, Babel W. Bioremediation of acid mine water using facultatively methylotrophic metal-tolerant sulfate-reducing bacteria. Microbiol Res 1997. [DOI: 10.1016/s0944-5013(97)80025-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Friedrich S, Morgan SB, Devine C. Children's attitudes and behavioral intentions toward a peer with Tourette syndrome. J Pediatr Psychol 1996; 21:307-19. [PMID: 8935235 DOI: 10.1093/jpepsy/21.3.307] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Examined children's ratings of attitudes and behavioral intentions toward a boy presented, on videotape, with or without symptoms of Tourette syndrome (TS). Effects of information about TS on these ratings were investigated as well as the influence of gender and grade. Children in Grades 3 and 5 were randomly assigned to one of three conditions: No TS, TS, or TS/information. On the attitude measure, children rated the peer presented with TS less positively than they did the peer presented without TS. On behavioral intention measures, no significant differences were found between conditions. Information about TS did not affect ratings. Implications of these findings as well as limitations of the study are discussed.
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Suerbaum S, Friedrich S. Helicobacter pylori does not have a hap mucinase gene that is quasi-identical to the Vibrio cholerae hap gene. Mol Microbiol 1996; 20:1113-4. [PMID: 8809763 DOI: 10.1111/j.1365-2958.1996.tb02551.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Suerbaum S, Friedrich S, Leying H, Opferkuch W. Expression of capsular polysaccharide determines serum resistance in Escherichia coli K92. ZENTRALBLATT FUR BAKTERIOLOGIE : INTERNATIONAL JOURNAL OF MEDICAL MICROBIOLOGY 1994; 281:146-57. [PMID: 7858342 DOI: 10.1016/s0934-8840(11)80565-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The amount of capsular polysaccharide expression has been shown to be the major determinant of serum resistance in Escherichia coli K1. E. coli K92, like K1, is a polymer of sialic acid molecules. It differs from K1 by containing both alpha (2.8) and alpha (2.9) linkages. Four strains of E. coli K92 were tested for serum resistance. Three strains were serum-resistant (50% normal human serum), one strain was moderately serum-sensitive. The serum-resistant strains expressed significantly more capsular polysaccharide than did the serum-sensitive strain. For each of the serum-resistant strains, six mutants were isolated by selection for resistance against infection with a K92-specific bacteriophage. All of the mutants expressed less capsular polysaccharide than the respective wild-type strains. All mutants were more sensitive to serum killing than the wild-type strains. In all groups, the mutants with lowest expression of capsular polysaccharide were highly serum-sensitive. Changes of outer membrane proteins or lipopolysaccharide patterns that were present in some mutants did not correlate with serum resistance properties of the mutants. Furthermore, it was investigated whether the presence of active serum had an influence on capsule expression. In the serum-sensitive strain, the presence of serum induced a significant and concentration-dependent increase of capsule expression. Serum had no effect on capsule expression by the serum-resistant strains. We conclude from the data that the expression of K92 capsular polysaccharide determines serum resistance in the strains examined.
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Vieth J, Sack G, Kober H, Friedrich S, Moeger A, Weise E, Daun A. The dipole density plot (DDP), a technique to show concentrations of dipoles. Physiol Meas 1993; 14 Suppl 4A:A41-4. [PMID: 8274983 DOI: 10.1088/0967-3334/14/4a/007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
To analyse spontaneous multichannel slow-wave MEG activity a tool was developed to extract focal abnormal activity with a higher spatial dipole density across time. The first version works on discrete volume units, the second version avoids a possible location error, works continuously and can be adjusted for individual slices three-dimensionally. The first version is used for screening and the second version is used to go into more detail. The dipole density plot (DDP) is not limited to single foci, nor to the single-dipole model; neither is it limited to the MEG. The DDP seems to be a valuable tool for detecting and locating lesions three-dimensionally within the brain.
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Vieth J, Kober H, Weise E, Daun A, Moeger A, Friedrich S, Pongratz H. Functional 3D localization of cerebrovascular accidents by magnetoencephalography (MEG). Neurol Res 1992; 14:132-4. [PMID: 1355869 DOI: 10.1080/01616412.1992.11740032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Spontaneous magnetic slow wave brain activity can be used to locate the underlying sources with sufficient accuracy by using the single current dipole model. To locate focal sources from spontaneous activity a tool had to be developed to extract focal densities of dipoles across time-the dipole density plot. The first version works on discrete volume units and is used for screening. The second version avoids a possible localization error and works continuously and this even is done on individual slices. The DDP seems to be a valuable tool for extracting and separating different focal sources from the background activity. Not only brain infarctions and haemorrhages (and cysts and angiomas) could be located, but also functional sources associated with TIAs even one week after the symptoms. First results let us assume that clinically silent TIAs also (in analogy to clinically silent brain infarctions) could be detected and located.
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98
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Gähler C, Friedrich S, Miles RO, Melchior H. Fiber optic temperature sensor using sampled homodyne detection. APPLIED OPTICS 1991; 30:2938-2940. [PMID: 20706337 DOI: 10.1364/ao.30.002938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A method of homodyne detection using laser emission frequency modulation and sampling of the interferometer output signal is described for a temperature sensor using a Mach-Zehnder all-fiber interferometer configuration. Both ac and dc signal detection are possible with this scheme. Temperature changes over the 5-80 degrees C range are measurable with a resolution of 1.4 mK by fringe counting and electronically determining the slope of the phase change.
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99
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Vieth J, Sack G, Kober H, Grummich P, Friedrich S, Moeger A, Weise E, Pongratz H. MAGNETOENCEPHALOPGRAPHY, A METHOD TO LOCALIZE CLINICALLY SILENT TRANSIENT ISCHEMIC ATTACKS (TIA) USING AN IMPROVED DIPOLE-DENSITY-PLOT. BIOMED ENG-BIOMED TE 1991. [DOI: 10.1515/bmte.1991.36.s1.155] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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100
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Friedrich S, Platonova NP, Karavaiko GI, Stichel E, Glombitza F. Chemical and microbiological solubilization of silicates. ACTA ACUST UNITED AC 1991. [DOI: 10.1002/abio.370110302] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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