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1.
Atherosclerosis ; 398: 118601, 2024 Sep 19.
Article in English | MEDLINE | ID: mdl-39342791

ABSTRACT

BACKGROUND: In 2012, the German Lipoprotein Apheresis Registry (GLAR) was launched. Real-world data on lipoprotein apheresis (LA) treatment are now available for a time period of 11 years. All patients received the maximally tolerated lipid-lowering therapy, which included statins, ezetimibe, bempedoic acid, and either proprotein convertase subtilisin/kexin type 9 (PCSK9) antibodies or antisense therapy. METHODS AND RESULTS: During the time period from 2012 to 2022, 92 German apheresis centers collected retrospective and prospective observational data of a total of 2,301 patients undergoing regular lipoprotein apheresis (LA) treatment of hypercholesterolemia or/and Lp(a)-hyperlipoproteinemia suffering from progressive atherosclerotic cardiovascular disease (ASCVD), with complete data sets of 1.125 patients, who were the subject of this analysis. More than 61,500 LA sessions are documented in the database. In 2022, all patients treated with LA demonstrated a significant immediate median reduction rate of LDL-C (68.8 %) and Lp(a) (72.9 %). Patient data were analyzed for the incidence rate of major coronary events (MACE) 1 and 2 years before the beginning of LA treatment (y-2 and y-1) and prospectively up to eleven years on LA treatment (y+1 to y+11). During the first two years of LA treatment (y+1 and y+2), a MACE reduction of 73 % was observed and continued to be low during y+3 to y+11, when all LA patients were analyzed. LA patients with only increased Lp(a) levels (Lp(a) ≥ 60 mg/dl (≥120 nmol/l) and an LDL-C < 100 mg/dl (<2.6 mmol/l)) had a higher MACE reduction (85 %; n = 443) in the first two years of LA treatment compared to LA patients with only increased LDL-C-levels (LDL-C ≥ 100 mg/dl (≥2.6 mmol/l); Lp(a) < 60 mg/dl (<120 nmol/l)) (53 %; n = 171). Adverse events of LA remained low (about 5 %) over the eleven years and mainly represented puncture problems (1.0 %). No side effects resulted in termination of LA therapy. CONCLUSIONS: The current analysis of GLAR data indicates that regular LA leads to very low incidence rates of cardiovascular events in patients with high LDL-C and/or high Lp(a) levels, progressive ASCVD, and maximally tolerated lipid-lowering medication, including proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition. Additionally, LA was safe with a low rate of adverse effects over an 11-year period. The number of enrolled patients and the duration of observation establish GLAR as the largest LA registry worldwide.

2.
Front Cardiovasc Med ; 11: 1401566, 2024.
Article in English | MEDLINE | ID: mdl-39211771

ABSTRACT

C-reactive protein (CRP) apheresis has been introduced in ST-elevation myocardial infarction and cardiogenic shock. Here, we describe a first-in-man application in non-ST-elevation acute coronary syndrome (NSTE-ACS). Seven NSTE-ACS patients with high CRP levels (range 14.2-154 mg/L) were treated with CRP apheresis. Treatment was well-tolerated. Patients were discharged in good clinical condition.

3.
Clin Res Cardiol Suppl ; 14(Suppl 1): 33-38, 2019 Apr.
Article in English | MEDLINE | ID: mdl-30838552

ABSTRACT

BACKGROUND: Lipoprotein(a) (Lp(a)) is a genetic risk factor for cardiovascular disease (CVD) and is associated with the induction and sustaining of atherosclerotic cardiovascular diseases (ASCVD). Since 2008 Lp(a) along with progressive CVD has been approved as an indication for regular lipoprotein apheresis (LA) in Germany. The German Lipoprotein Apheresis Registry (GLAR) has been initiated to provide statistical evidence for the assessment of extracorporeal procedures to treat dyslipidemia for both LDL-cholesterol (LDL-C) and Lp(a). The GLAR now allows prospective investigations over a 5-year period about annual incidence rates of cardiovascular events. Here Lp(a) patients (LDL-C < 100 mg/dl; Lp(a) > 60 mg/dl or >120 nmol/l) showed the same reduction of major coronary (83%) and non-coronary events (63%) as had been formerly shown in the Pro(a)LiFe study. However, Lp(a) is not only an apolipoprotein(a) (apo(a)) and LDL-C containing particle, which is covalently bound to a LDL-C core by a disulphide bridge. The composition of this particle, inter alia containing oxidized phospholipids, gives pro-atherosclerotic, pro-inflammatory, and pro-thrombotic properties, inducing atherosclerotic processes mainly in the arterial wall. However, recent investigations have shown that a reduction of inflammatory settings without LDL-C or Lp(a) reduction may reduce ASCVD events. Lipoprotein apheresis (LA) could not only reduce LDL-C and Lp(a) in parallel, but also different inflammatory and coagulation parameters. In summary lipoprotein apheresis is not only anti-atherosclerotic, but also anti-inflammatory and anti-thrombotic and therefore an ideal treatment option with respect to the shown reduction of major adverse coronary events (MACE) and major adverse non-coronary events (MANCE) by reducing Lp(a) levels.


Subject(s)
Atherosclerosis/blood , Blood Component Removal/methods , Cardiovascular Diseases/blood , Lipoprotein(a)/blood , Atherosclerosis/genetics , Atherosclerosis/therapy , Cardiovascular Diseases/genetics , Cardiovascular Diseases/therapy , Cholesterol, LDL/blood , Dyslipidemias/therapy , Genetic Predisposition to Disease , Germany , Humans , Lipoprotein(a)/genetics , Registries , Risk Factors
4.
Atheroscler Suppl ; 30: 44-49, 2017 Nov.
Article in English | MEDLINE | ID: mdl-29096860

ABSTRACT

According to current European guidelines, lipid lowering therapy for progressive cardiovascular disease including cardiovascular events has to be focused on a target level for LDL-C. In contrast for Lp(a) a threshold has to be defined with respect to the method of measurement. However, due to new lipid lowering drug developments like PCSK9-inhibitors (PCSK-9-I) a therapeutic algorithm for patients with severe hypercholesterolemia or isolated Lipoprotein(a)-hyperlipoproteinemia with progressive cardiovascular disease may be necessary to manage the use of PCSK9-I, lipoprotein apheresis (LA) or both. The therapeutic approach for patients with homozygous familial hypercholesterolemia is unambiguous: In addition to LA, in order to improve LDL-C reduction, PCSK9-I could be applied. In patients with heterozygous familial hypercholesterolemia, PCSK9-I is to be applied first. If in addition to a pronounced LDL-C elevation, cardiovascular complications exist or if imaging techniques documented atherosclerotic changes pre-disposing for a cardiovascular event while LDL-C reduction is insufficiently reduced (LDL-C > 100 mg/dl (2.6 mmol/l)), LA treatment should then be applied as last resort. In patients with elevated Lp(a) concentrations (Lp(a) > 60 mg/dl (>120 nmol/l)) and established cardiovascular disease, therapy should rely primarily on LA methods. If in addition to high Lp(a) levels insufficiently treated LDL-C concentrations (LDL-C > 100 mg/dl (2.6 mmol/l)) exist, in rare cases PCSK9-I can supplement the lipid lowering concept.


Subject(s)
Anticholesteremic Agents/therapeutic use , Blood Component Removal/methods , Cardiovascular Diseases/prevention & control , Cholesterol, LDL/blood , Hyperlipoproteinemia Type II/therapy , Lipoprotein(a)/blood , PCSK9 Inhibitors , Serine Proteinase Inhibitors/therapeutic use , Anticholesteremic Agents/adverse effects , Biomarkers/blood , Blood Component Removal/adverse effects , Cardiovascular Diseases/etiology , Combined Modality Therapy , Germany , Humans , Hyperlipoproteinemia Type II/blood , Hyperlipoproteinemia Type II/complications , Hyperlipoproteinemia Type II/enzymology , Proprotein Convertase 9/metabolism , Risk Assessment , Risk Factors , Serine Proteinase Inhibitors/adverse effects , Treatment Outcome
5.
Atheroscler Suppl ; 30: 50-55, 2017 Nov.
Article in English | MEDLINE | ID: mdl-29096861

ABSTRACT

BACKGROUND: In recent years the Federal Joint Committee (G-BA), a paramount decision-making body of the German health care system required a reassessment of the approval of chronic lipoprotein apheresis therapy for regular reimbursement. Since 2005 an interdisciplinary German apheresis working group has been established by members of both German Societies of Nephrology. In 2009 the working group completed the indication for lipoprotein apheresis with respect to current cardiovascular guidelines and current scientific knowledge for the registry. In 2011 the German Lipoprotein Apheresis Registry (GLAR) was launched and data acquired over nearly 5 years can now be reported. METHODS AND RESULTS: All data were collected and analyzed during the time period 2012-2015. Over this time interval, 68 German apheresis centers collected retrospective and prospective observational data of 1.283 patients undergoing lipoprotein apheresis (LA) treatment of high LDL-cholesterol (LDL-C) levels and/or high lipoprotein(a) (Lp(a)) levels suffering from progressive cardiovascular disease (CVD). A total of 15,167 documented LA treatments were investigated. All patients treated by LA exhibited a median LDL-C reduction rate of 68.6%, and a median Lp(a) reduction rate of 70.4%. Analogue to the Pro(a)LiFe pattern, patient data were analyzed and compared with respect to the incidence rate of coronary events (MACE) 1 and 2 years before the start of LA treatment (y-2 and y-1) and prospectively one year on LA treatment (y+1). During the first year of LA treatment a MACE reduction of 97% was be observed. In the years considered, LA treatment side effects occurred at a low rate (ca. 5%) and mainly comprised puncture problems. CONCLUSIONS: For the first time data generated by the GLAR shows that LA lowers the incidence rate of cardiovascular events in patients with high LDL-C and/or high Lp(a) levels, progressive CVD and maximally tolerated lipid lowering medication. In addition LA treatments were found to be safe, exhibiting a low rate of side effects.


Subject(s)
Blood Component Removal/methods , Cardiovascular Diseases/prevention & control , Cholesterol, LDL/blood , Hypercholesterolemia/therapy , Lipoprotein(a)/blood , Registries , Adult , Aged , Aged, 80 and over , Biomarkers/blood , Blood Component Removal/adverse effects , Cardiovascular Diseases/etiology , Female , Germany , Humans , Hypercholesterolemia/blood , Hypercholesterolemia/complications , Male , Middle Aged , Program Evaluation , Research Design , Risk Assessment , Risk Factors , Time Factors , Treatment Outcome , Young Adult
7.
Clin Res Cardiol Suppl ; 12(Suppl 1): 44-49, 2017 Mar.
Article in English | MEDLINE | ID: mdl-28233268

ABSTRACT

BACKGROUND: Since 2005 an interdisciplinary German apheresis working group has been established by members of both German Societies of Nephrology and of Lipidologists and completed the data set for the registry according to the current guidelines and the German indication guideline for apheresis in 2009. In 2011 the German Lipoprotein Apheresis Registry (GLAR) was launched and data are available over nearly 5 years now. METHODS AND RESULTS: During the time period 2012-2016, 71 German apheresis centers collected retrospective and prospective observational data of 1435 patients undergoing lipoprotein apheresis (LA) treatment of high LDL-C levels and/or high Lp (a) levels suffering from cardiovascular disease (CVD) or progressive CVD. A total of 15,527 completely documented LA treatments were entered into the database. All patients treated by LA showed a median LDL-C reduction rate of 67.5%, and a median Lp (a) reduction rate of 71.1%. Analog to the Pro(a)LiFe pattern, patient data were analyzed to the incidence rate of coronary events (MACE) 1 and 2 years before the beginning of LA treatment (y-2 and y­1) and prospectively two years on LA treatment (y + 1 and y + 2). During two years of LA treatment a MACE reduction of 78% was observed. In the years considered, side effects of LA treatment were low (5.9%) and mainly comprised puncture problems. CONCLUSIONS: The data generated by the GLAR shows that LA lowers the incidence rate of cardiovascular events in patients with high LDL-C and/or high Lp (a) levels, progressive CVD, and maximally tolerated lipid lowering medication. In addition, LA treatments were found to be safe with a low rate of side effects.


Subject(s)
Blood Component Removal , Cardiovascular Diseases/prevention & control , Hyperlipoproteinemias/therapy , Lipoprotein(a)/blood , Adult , Aged , Aged, 80 and over , Biomarkers/blood , Blood Component Removal/adverse effects , Cardiovascular Diseases/blood , Cardiovascular Diseases/epidemiology , Cholesterol, LDL/blood , Female , Germany/epidemiology , Humans , Hyperlipoproteinemias/blood , Hyperlipoproteinemias/epidemiology , Incidence , Lipoprotein(a)/genetics , Male , Middle Aged , Prospective Studies , Registries , Retrospective Studies , Risk Factors , Time Factors , Treatment Outcome , Young Adult
9.
Atheroscler Suppl ; 18: 199-208, 2015 May.
Article in English | MEDLINE | ID: mdl-25936327

ABSTRACT

OBJECTIVES: Iron deficiency (ID) and iron deficiency anemia (IDA) are common findings in patients undergoing lipoprotein apheresis (LA). Different intravenous (iv) formulations are used to treat ID in LA patients, however guidelines and data on ID/IDA management in LA patients are lacking. We therefore performed a prospective observational multi-center cohort study of ID/IDA in LA patients, comparing two approved i.v. iron formulations, ferric gluconate (FG) and ferric carboxymaltose (FCM). METHODS: Inclusion criteria were a) serum ferritin <100 µg/L or b) serum ferritin <300 µg/L and transferrin saturation <20%. Patients received either FG (62.5 mg weekly) or FCM (500 mg once in ID or up to 1000 mg if IDA was present) i.v. until iron deficiency was resolved. Efficacy and safety were determined by repeated laboratory and clinical assessment. Iron parameters pre and post apheresis were measured to better understand the pathogenesis of ID/IDA in LA patients. RESULTS: 80% of LA patients treated at the three participating centers presented with ID/IDA; 129 patients were included in the study. Serum ferritin and transferrin levels were reduced following apheresis (by 18% (p < 0.0001) and by 13% (p < 0.0001) respectively). Both FG and FCM were effective and well tolerated in the treatment of ID/IDA in LA patients. FCM led to a quicker repletion of iron stores (p < 0.05), while improvement of ID/IDA symptoms was not different. Number and severity of adverse events did not differ between FG and FCM, no severe adverse events occurred. CONCLUSIONS: Our results suggest that FG and FCM are equally safe, well-tolerated and effective in treating ID/IDA in LA patients. These data form the basis for follow-up randomized controlled trials to establish clinical guidelines.


Subject(s)
Anemia, Iron-Deficiency/drug therapy , Blood Component Removal/adverse effects , Ferric Compounds/therapeutic use , Hematinics/therapeutic use , Hyperlipoproteinemias/therapy , Lipoproteins, LDL/blood , Maltose/analogs & derivatives , Aged , Anemia, Iron-Deficiency/blood , Anemia, Iron-Deficiency/diagnosis , Anemia, Iron-Deficiency/etiology , Biomarkers/blood , Blood Component Removal/methods , Drug Administration Schedule , Female , Ferric Compounds/administration & dosage , Ferric Compounds/adverse effects , Ferritins/blood , Germany , Hematinics/administration & dosage , Hematinics/adverse effects , Humans , Hyperlipoproteinemias/blood , Hyperlipoproteinemias/diagnosis , Infusions, Intravenous , Iron/blood , Male , Maltose/administration & dosage , Maltose/adverse effects , Maltose/therapeutic use , Middle Aged , Prospective Studies , Time Factors , Transferrin/metabolism , Treatment Outcome
10.
Nervenarzt ; 86(2): 179-86, 2015 Feb.
Article in German | MEDLINE | ID: mdl-25604838

ABSTRACT

BACKGROUND: Approximately 25 % of women with multiple sclerosis (MS) suffer clinically relevant relapses during pregnancy. Almost all disease-modifying drugs are contraindicated in pregnancy. High-dose glucocorticoids have some serious risks, especially within the first trimester. Tryptophan immunoadsorption (IA) provides a safe option to treat MS relapses during pregnancy. OBJECTIVES: In this case series we describe for the first time the use of tryptophan IA for MS and neuromyelitis optica (NMO) relapses during pregnancy and breastfeeding. PATIENTS AND METHODS: In this study a total of 9 patients were retrospectively analyzed of which 7 patients received IA treatment during pregnancy, 2 during breastfeeding and 4-6 tryptophan IA treatments were performed per patient with the single use tryptophan adsorber. Primary outcome was symptom improvement of the relapse. RESULTS: In this study four patients with MS and one with NMO relapse during pregnancy were treated with IA without preceding glucocorticoid pulse therapy. The MS patients showed improvement in the expanded disability status scale (EDSS) by at least one point, the NMO patient showed significant improvement in visual acuity and two pregnant patients with steroid-refractory relapses showed clinically relevant improvement after IA. Of the patients two suffered from steroid-refractory relapses during breastfeeding and relapse symptoms improved in both cases after treatment with IA. All treatments were well tolerated and no serious adverse events occurred. CONCLUSION: Tryptophan IA was found to be safe, well-tolerated and effective in the treatment of MS and NMO relapses during pregnancy and breastfeeding, sometimes without preceding glucocorticoid pulse therapy. A binding recommendation is limited without prospective clinical studies.


Subject(s)
Breast Feeding , Immunosorbent Techniques , Multiple Sclerosis/therapy , Neuromyelitis Optica/therapy , Pregnancy Complications/therapy , Tryptophan/immunology , Tryptophan/isolation & purification , Acute Disease , Adult , Female , Humans , Multiple Sclerosis/diagnosis , Multiple Sclerosis/immunology , Neuromyelitis Optica/diagnosis , Neuromyelitis Optica/immunology , Pregnancy , Pregnancy Complications/diagnosis , Pregnancy Complications/immunology , Recurrence
11.
J Chem Phys ; 138(6): 061104, 2013 Feb 14.
Article in English | MEDLINE | ID: mdl-23425454

ABSTRACT

We have studied the optical recombination channels of TbCl(3) using x-ray excited optical luminescence at the N(4,5) absorption edge of Tb (giant resonance) in both the energy and time domain. The luminescence exhibits a relatively fast (5)D(3), and a slow (5)D(4) decay channel in the blue and green, respectively. The rather short lifetime of the (5)D(3) state indicates that the decay is mainly driven by Tb-Tb ion interaction via non-radiative energy transfer (cross-relaxation). At the giant resonance the X-ray Absorption Near Edge Structure (XANES) recorded using partial photoluminescence yield is inverted. In the pre-edge region the contrast of the spectral feature is significantly better in optical XANES than in total electron yield. Changes in the intensity of (5)D(3)-(7)F(5) (544 nm) and (5)D(4)-(7)F(6) (382 nm) optical transitions as the excitation energy is tuned across the giant resonance are also noted. The results provide detailed insight into the dynamics of the optical recombination channels and an alternative method to obtain high sensitivity, high energy resolution XANES at the giant resonance of light emitting rare-earth materials.

12.
Nat Commun ; 3: 1023, 2012.
Article in English | MEDLINE | ID: mdl-22929780

ABSTRACT

A collective order of spin and charge degrees of freedom into stripes has been predicted to be a possible ground state of hole-doped CuO(2) planes, which are the building blocks of high-temperature superconductors. In fact, stripe-like spin and charge order has been observed in various layered cuprate systems. For the prototypical high-temperature superconductor La(2-x)Sr(x)CuO(4), no charge-stripe signal has been found so far, but several indications for a proximity to their formation. Here we report the observation of a pronounced charge-stripe signal in the near surface region of 12-percent doped La(2-x)Sr(x)CuO(4). We conclude that this compound is sufficiently close to charge stripe formation that small perturbations or reduced dimensionality near the surface can stabilize this order. Our finding of different phases in the bulk and near the surface of La(2-x)Sr(x)CuO(4) should be relevant for the interpretation of data from surface-sensitive probes, which are widely used for La(2-x)Sr(x)CuO(4) and similar systems.

13.
Nervenarzt ; 82(12): 1590-5, 2011 Dec.
Article in German | MEDLINE | ID: mdl-21667161

ABSTRACT

BACKGROUND: Multiple sclerosis (MS) is a chronic inflammatory demyelinating immune-mediated disease of the central nervous system, often associated with relapses. Plasma exchange (PE) has become established as an escalation therapy for steroid-unresponsive relapses in national and international guidelines. PE is a non-selective apheresis method with elimination of the entire plasma with subsequent substitution. Selective extracorporeal elimination of autoantibodies and immune complexes with immunoadsorption (IA) is increasingly replacing PE for the treatment of autoimmune neurological diseases due to its equivalent efficacy and advantageous safety profile. The use of IA for MS still remains to become established. The aim of this retrospective investigation was to evaluate efficacy and safety of IA in patients with steroid-unresponsive relapses. PATIENTS AND METHODS: Fourteen patients with steroid-unresponsive MS relapses were retrospectively analysed. Patients received six IA treatments within 2 weeks using the single-use tryptophan adsorber. Peripheral venous access was used in 11 patients, and 3 patients needed a central line. The plasma volume treated was 2 l per IA. Efficacy criteria were improvement in symptoms of MS relapses which were measured with the Kurtzke scale (EDSS, FS) and visual acuity measurements for patients with optic neuritis. RESULTS: In 12 of 14 patients the major symptom of MS relapse improved to a clinically relevant extent after tryptophan IA; no patient got worse, corresponding to a response rate of 86%. Mean EDSS and FS in patients with spastic paresis (n=4) and dizziness (n=2) as well as mean visual acuity in patients with optic neuritis (n=8) significantly improved after IA. IA treatments were safe, with good tolerability, and no severe adverse events occurred. CONCLUSION: Immunoadsorption for the treatment of steroid-unresponsive MS relapses was safe and effective. The response rate was comparable to published results with PE. With IA, in contrast to unselective PE, administration of human plasma products is not necessary, avoiding associated risks.


Subject(s)
Immunosorbent Techniques , Multiple Sclerosis/diagnosis , Multiple Sclerosis/therapy , Plasma Exchange/methods , Steroids/therapeutic use , Adult , Female , Humans , Male , Recurrence , Treatment Failure
14.
J Chem Phys ; 130(8): 084707, 2009 Feb 28.
Article in English | MEDLINE | ID: mdl-19256619

ABSTRACT

The electronic structure and optical properties of biaxial ZnO-ZnS heterostructure nanoribbons (NRs) have been investigated using x-ray absorption near-edge structures (XANES) and x-ray excited optical luminescence (XEOL). The XANES were recorded in total electron yield and wavelength-selected photoluminescence yield across the K- and L(3,2)-edges of zinc and sulfur and the K-edge of oxygen. The XEOL from the NRs exhibit a very weak band-gap emission at 392 nm and two intense defect emissions at 491 and 531 nm. The synchrotron x-ray pulse ( approximately 100 ps, 153 ns repetition rate) was used to track the optical decay dynamics from ZnO-ZnS NR, which can be described by two lifetimes (7.6 and 55 ns). Comparison with similar measurements for ZnO and ZnS nanowires reveals that the luminescence from ZnO-ZnS NRs was dominated by the ZnO component of the NR as the ZnS component contributes little. The implication of this observation is discussed.

15.
HNO ; 56(9): 961-6, 2008 Sep.
Article in German | MEDLINE | ID: mdl-18719869

ABSTRACT

Disturbances of cochlear microcirculation are among the most discussed causes of sudden sensorineural hearing loss. Increased levels of cholesterol and fibrinogen seem to act as risk factors for inner ear disorders. Fibrinogen/LDL apheresis greatly reduces the concentration of plasma fibrinogen thus leading to improved cochlear blood flow. In a retrospective case series remission rates of 152 patients suffering from sudden sensorineural hearing loss and resistant to former treatment were investigated after treatment with a single apheresis. Complete remission was reported in 11% of patients, partial remission in 43%. 37% had no change of hearing threshold and 2% reported a decrease in hearing. Rates of complete remissions decreased from 22% within the first 2 weeks after onset of hearing loss to 14% after 6 weeks. In the same period of time rates of partial remissions decreased from 33% to 13%. The present study shows that apheresis achieved complete or partial remission in 54% of patients even after unsuccessful treatment with another therapy and the therapeutic window lies by approximately 6 weeks.


Subject(s)
Blood Component Removal/methods , Fibrinogen/administration & dosage , Hearing Loss, Sudden/drug therapy , Lipoproteins, LDL/administration & dosage , Adolescent , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Treatment Outcome , Young Adult
16.
Phys Rev Lett ; 100(22): 227203, 2008 Jun 06.
Article in English | MEDLINE | ID: mdl-18643455

ABSTRACT

For epitaxial trilayers of the magnetic rare-earth metals Gd and Tb, exchange coupled through a nonmagnetic Y spacer layer, element-specific hysteresis loops were recorded by the x-ray magneto-optical Kerr effect at the rare-earth M5 thresholds. This allowed us to quantitatively determine the strength of interlayer exchange coupling (IEC). In addition to the expected oscillatory behavior as a function of spacer-layer thickness dY, a temperature-induced sign reversal of IEC was observed for constant dY, arising from magnetization-dependent electron reflectivities at the magnetic interfaces.

17.
J Chem Phys ; 128(14): 144703, 2008 Apr 14.
Article in English | MEDLINE | ID: mdl-18412467

ABSTRACT

X-ray excited optical luminescence (XEOL) and x-ray absorption near-edge structure in total electron, x-ray fluorescence, and photoluminescence yields at Sn M5,4-, O K-, and Sn K-edges have been used to study the luminescence from SnO2 nanoribbons. The effect of the surface on the luminescence from SnO2 nanoribbons was studied by preferential excitation of the ions in the near-surface region and at the normal lattice positions, respectively. No noticeable change of luminescence from SnO2 nanoribbons was observed if the Sn ions in the near-surface region were excited selectively, while the luminescence intensity changes markedly when Sn or O ions at the normal lattice positions were excited across the corresponding edges. Based on the experimental results, we show that the luminescence from SnO2 nanoribbons is dominated by energy transfer from the excitation of the whole SnO2 lattice to the surface states. Surface site specificity is not observable due to its low concentration and weak absorption coefficient although the surface plays an important role in the emission as a luminescence center. The energy transfer and site specificity of the XEOL or the lack of the site specificity from a single-phase sample is discussed.

18.
J Phys Chem B ; 109(8): 3120-5, 2005 Mar 03.
Article in English | MEDLINE | ID: mdl-16851331

ABSTRACT

ZnO nanostructures, including single-crystal nanowires, nanoneedles, nanoflowers, and tubular whiskers, have been fabricated at a modestly low temperature of 550 degrees C via the oxidation of metallic Zn powder without a metal catalyst. Specific ZnO nanostructures can be obtained at a specific temperature zone in the furnace depending on the temperature and the pressure of oxygen. Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD) studies show that ZnO nanostructures thus prepared are single crystals with a wurtzite structure. X-ray excited optical luminescence (XEOL) from the ZnO nanostructures show noticeable morphology-dependent luminescence. Specifically, ZnO nanowires of around 15 nm in diameter emit the strongest green light. The morphology of these nanostructures, their XEOL, and the implication of the results will be discussed.


Subject(s)
Metal Nanoparticles/chemistry , Nanotechnology/methods , Synchrotrons , Zinc Oxide/chemistry , Light , Luminescence , Microscopy, Electron, Scanning , Microscopy, Electron, Transmission , Models, Chemical , Nanoparticles/chemistry , Silicon/chemistry , Temperature , X-Ray Diffraction , X-Rays , Zinc/chemistry
19.
Phys Rev Lett ; 86(15): 3415-8, 2001 Apr 09.
Article in English | MEDLINE | ID: mdl-11327984

ABSTRACT

Magneto-optical methods in the visible light regime generally lack element specificity, which has become a considerable shortcoming in research on advanced heteromagnetic systems. Using circularly polarized soft x rays tuned to a 4d-4f core-level transition of a lanthanide element, the specularly reflected x-ray intensity changes proportionally to the magnetization of this element and, e.g., hystereses are easily measured element specifically. In contrast to the case of visible light, temperature dependent 4d-4f magneto-optical signals are not influenced by the thermal lattice expansion.

20.
J Drug Target ; 8(3): 173-84, 2000.
Article in English | MEDLINE | ID: mdl-10938527

ABSTRACT

To take advantage of the cytoadhesive characteristics of Wheat germ agglutinin (WGA) for improved particulate drug delivery, the interaction between WGA-grafted poly(D,L-lactic-co-glycolic acid)-microspheres and Caco-2 monolayers was investigated using bovine serum albumin (BSA) or glycine coated microspheres as a control. Covalent immobilization of WGA by the carbodiimide/N-hydroxysuccinimide-method on 4 microm microspheres yielded a surface density of 9.67+/-1.21x10(6) molecules/particle, whereas 0.22+/-0.04x10(6) WGA-molecules were bound by physical adsorption. After storage for 21 days in HEPES-buffer and treatment of the particles with 5 M urea, 86% of covalently linked lectin was still attached to the particles. At 4 degrees C the Caco-2 binding rate of both, WGA- and BSA-modified particles increased with addition of increasing numbers of particles until saturation was reached at 38150+/-1740 (WGA) or 12066+/-1195 (BSA) microspheres bound/mm(2) Caco-2 monolayer. Inhibition of Caco-2 binding of WGA-functionalized microspheres by chitotriose indicated for specificity of the interaction. As observed by confocal laser scanning microscopy, the fluorescein-loading of the particles was accumulated intracellularly after incubation of Caco-2 monolayers with WGA-modified microspheres contrary to glycine-grafted microspheres. Additionally, in case of WGA-functionalized microspheres the amount of cell associated fluorescein was 200-fold higher than that of the free solution. In conclusion, WGA-modified microspheres are expected to enhance intestinal transport of incorporated drugs due to cytoadhesion provided by the lectin coating.


Subject(s)
Caco-2 Cells/metabolism , Lactic Acid/pharmacokinetics , Polyglycolic Acid/pharmacokinetics , Polymers/pharmacokinetics , Wheat Germ Agglutinins/pharmacokinetics , Animals , Cattle , Drug Carriers , Humans , Lactic Acid/chemical synthesis , Lectins/chemical synthesis , Lectins/pharmacokinetics , Microspheres , Polyglycolic Acid/chemical synthesis , Polylactic Acid-Polyglycolic Acid Copolymer , Polymers/chemical synthesis , Wheat Germ Agglutinins/chemical synthesis
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