Charge-State-Enhanced Ion Sputtering of Metallic Gold Nanoislands.

Experimental results on the charge-state-dependent sputtering of metallic gold nanoislands are presented. Irradiations with slow highly charged ions of metallic targets were previously considered to show no charge state dependent effects on ion-induced material modification, since these materials possess enough free electrons to dissipate the deposited potential energy before electron-phonon coupling can set in. By reducing the size of the target material down to the nanometer regime and thus enabling a geometric energy confinement, a possibility is demonstrated to erode metallic surfaces by charge state related effects in contrast to regular kinetic sputtering.

A high temperature dual-mode quartz crystal microbalance technique for erosion and thermal desorption spectroscopy measurements.

An improved quartz crystal microbalance measurement method is described, which allows us to determine erosion, implantation, and release rates of thin films, during changing temperatures and up to 700 K. A quasi-simultaneous excitation of two eigenmodes of the quartz resonator is able to compensate for frequency drifts due to temperature changes. The necessary electronics, the controlling behavior, and the dual-mode temperature compensation are described. With this improved technique, quantitative in situ temperature-programmed desorption measurements are possible and the quartz crystal microbalance can be used for quantification of thermal desorption spectroscopy measurements with a quadrupole mass spectrometer. This is demonstrated by a study of the retention and release behavior of hydrogen isotopes in fusion-relevant materials. We find that more than 90% of the deuterium implanted into a thin film of beryllium is released during a subsequent temperature ramp up to 500 K.

Salmonella Typhimurium biofilm disruption by a human antibody that binds a pan-amyloid epitope on curli.

Bacterial biofilms, especially those associated with implanted medical devices, are difficult to eradicate. Curli amyloid fibers are important components of the biofilms formed by the Enterobacteriaceae family. Here, we show that a human monoclonal antibody with pan-amyloid-binding activity (mAb 3H3) can disrupt biofilms formed by Salmonella enterica serovar Typhimurium in vitro and in vivo. The antibody disrupts the biofilm structure, enhancing biofilm eradication by antibiotics and immune cells. In mice, 3H3 injections allow antibiotic-mediated clearance of catheter-associated S. Typhimurium biofilms. Thus, monoclonal antibodies that bind a pan-amyloid epitope have potential to prevent or eradicate bacterial biofilms.

A phase 3 trial of IV immunoglobulin for Alzheimer disease.

OBJECTIVE: We tested biweekly infusions of IV immunoglobulin (IVIg) as a possible treatment for mild to moderate Alzheimer disease (AD) dementia. METHODS: In a phase 3, double-blind, placebo-controlled trial, we randomly assigned 390 participants with mild to moderate AD to receive placebo (low-dose albumin) or IVIg (Gammagard Liquid; Baxalta, Bannockburn, IL) administered IV at doses of 0.2 or 0.4 g/kg every 2 weeks for 18 months. The primary cognitive outcome was change from baseline to 18 months on the 11-item cognitive subscale of the Alzheimer's Disease Assessment Scale; the primary functional outcome was 18-month change on the Alzheimer's Disease Cooperative Study-Activities of Daily Living Inventory. Safety and tolerability data, as well as serial MRIs and plasma samples, were collected throughout the study from all enrolled participants. RESULTS: No beneficial effects were observed in the dual primary outcome measures for the 2 IVIg doses tested. Significant decreases in plasma Aß42 (but not Aß40) levels were observed in IVIg-treated participants. Analysis of safety data showed no difference between IVIg and placebo in terms of the rate of occurrence of amyloid-related imaging abnormalities (brain edema or microhemorrhage). IVIg-treated participants had more systemic reactions (chills, rashes) but fewer respiratory infections than participants receiving placebo. CONCLUSIONS: Participants with mild to moderate AD showed good tolerability of treatment with low-dose human IVIg for 18 months but did not show beneficial effects on cognition or function relative to participants who received placebo. CLINICALTRIALSGOV IDENTIFIER: NCT00818662. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that IVIg infusions performed every 2 weeks do not improve cognition or function at 18 months in patients with mild to moderate AD.

Effective anti-Alzheimer Aß therapy involves depletion of specific Aß oligomer subtypes.

BACKGROUND: Recent studies have implicated specific assembly subtypes of ß-amyloid (Aß) peptide, specifically soluble oligomers (soAß) as disease-relevant structures that may underlie memory loss in Alzheimer disease. Removing existing soluble and insoluble Aß assemblies is thought to be essential for any attempt at stabilizing brain function and slowing cognitive decline in Alzheimer disease. IV immunoglobulin (IVIg) therapies have been shown to contain naturally occurring polyclonal antibodies that recognize conformational neoepitopes of soluble or insoluble Aß assemblies including soAß. These naturally occurring polyclonal antibodies have been suggested to underlie the apparent clinical benefits of IVIg. However, direct evidence linking anti-Aß antibodies to the clinical bioactivity of IVIg has been lacking. METHODS: Five-month-old female Dutch APP E693Q mice were treated for 3 months with neat IVIg or with IVIg that had been affinity-depleted over immobilized Aß conformers in 1 of 2 assembly states. Memory was assessed in a battery of tests followed by quantification of brain soAß levels using standard anti-soAß antibodies. RESULTS: We provide evidence that NU4-type soAß (NU4-soAß) assemblies accumulate in the brains of Dutch APP E693Q mice and are associated with defects in memory, even in the absence of insoluble Aß plaques. Memory benefits were associated with depletion from APP E693Q mouse brain of NU4-soAß and A11-soAß but not OC-type fibrillar Aß oligomers. CONCLUSIONS: We propose that targeting of specific soAß assembly subtypes may be an important consideration in the therapeutic and/or prophylactic benefit of anti-Aß antibody drugs.

Age matters: Young T lymphocytes offer better protection from myeloma proliferation.

BACKGROUND: The incidence and growth of cancer has been reported to increase with age and/or impaired T lymphocyte function. RESULTS: Consistent with these observations, we found that a monoclonal serum immunoglobulin (mIgG2b), rarely detectable after the injection of 5T33 murine multiple myeloma (MMM) cells into 3-4 month old wild-type C57BL/6 mice was seen more frequently in 18-20 month old wild-type C57BL/6 mice and in 3-4 month old Rag1-deficient C57BL/6 mice. These observations were confirmed and extended using more sensitive assays such as quantitation of splenic mRNA specific for the canonical 5T33 monoclonal IgG2b produced by 5T33 myeloma cells and the most sensitive assay, photon-imaging of mice injected with 5T33 cells, stably transfected with fire-fly luciferase gene (5T33L cells), which emit photons after the injection of luciferin. Furthermore, the proliferation of 5T33L myeloma cells in Rag1-deficient C57BL/6 mice was greater in mice which also received spleen T cells from 18-20 month old C57BL/6 wild-type mice compared to mice which received splenic T cells from 3-4 month old C57BL/6 wild-type mice. Thus, immune reconstitution of C57BL/6 mice with splenic T cells from young wild-type mice offered greater protection from progressive growth of 5T33L myeloma cells than did reconstitution with splenic T cells from old mice. CONCLUSIONS: Our findings support the hypothesis that age-associated changes in splenic T cell function contribute to the increased growth of 5T33 MMM cells in old compared to young C57BL/6 mice. Should similar processes occur in humans, increasing the anti-myeloma activity of T cells in old patients with multiple myeloma or transferring cryopreserved, young, autologous, T cells might benefit elderly patients with multiple myeloma.

Alzheimer's disease and Down's syndrome: treating two paths to dementia.

Successful therapy of dementia, like any disease, depends upon understanding its pathogenesis. This review contrasts the dominant pathways to dementia which differ in Alzheimer's disease (AD) and in Down's syndrome (DS). Impaired clearance of neurotoxic amyloid beta peptides (Abeta) leads to dementia in AD. In DS over-production of Abeta plays the dominant role in the development of dementia. It follows, therefore, that the therapy of AD and DS should reflect a different balance between the dominant agent that inhibits the synthesis of Abeta in the brain in AD and increase the clearance of Abeta from the cerebrospinal DS.

Measurement of anti-beta amyloid antibodies in human blood.

The human IgG repertoire contains endogenous antibodies against beta amyloid (Aß) that may be relevant to the pathogenesis and treatment of Alzheimer's disease. There have been widely disparate estimates of the levels of these antibodies in human plasma. We identify factors that have contributed to these disparities and describe improved methods for measuring anti-Aß antibodies in blood. These methods include isolating immunoglobulin by thiophilic chromatography and using chaotropic salts to dislodge weakly bound antibodies without significantly reducing the binding of specific anti-Aß antibodies. Using these methods, we show that human blood contains polyvalent IgG antibodies that bind to Aß with relatively low avidity and specificity, as well as IgG antibodies that bind to linear and conformational epitopes on amyloid monomers and aggregates with moderate to high avidity.

Reduced EBF expression underlies loss of B-cell potential of hematopoietic progenitors with age.

Aging is accompanied by a reduction in the generation of B lymphocytes leading to impaired immune responses. In this study, we have investigated whether the decline in B lymphopoiesis is due to age-related defects in the hematopoietic stem cell compartment. The ability of hematopoietic stem cells from old mice to generate B cells, as measured in vitro, is decreased 2-5-fold, while myeloid potential remains unchanged. This age-related decrease in B-cell potential is more marked in common lymphoid progenitors (CLP) and was associated with reduced expression of the B-lineage specifying factors, EBF and Pax5. Notably, retrovirus-mediated expression of EBF complemented the age-related loss of B-cell potential in CLP isolated from old mice. Furthermore, transduction of CLP from old mice with a constitutively active form of STAT5 restored both EBF and Pax5 expression and increased B-cell potential. These results are consistent with a mechanism, whereby reduced expression of EBF with age decreases the frequency with which multipotent hematopoietic progenitors commit to a B-cell fate, without altering their potential to generate myeloid cells.

18-Month study of intravenous immunoglobulin for treatment of mild Alzheimer disease.

Intravenous immunoglobulin (IVIg) has been proposed as a potential agent for Alzheimer's disease (AD) immunotherapy because it contains antibodies against beta-amyloid (Abeta). We carried out an open label dose-ranging study in 8 mild AD patients in which IVIg was added to approved AD therapies for 6 months, discontinued, and then resumed for another 9 months. Infusions were generally well-tolerated. Anti-Abeta antibodies in the serum from AD patients increased in proportion to IVIg dose and had a shorter half-life than anti-hepatitis antibodies and total IgG. Plasma Abeta levels increased transiently after each infusion. Cerebrospinal fluid Abeta decreased significantly at 6 months, returned to baseline after washout and decreased again after IVIg was re-administered for an additional 9 months. Mini-mental state scores increased an average of 2.5 points after 6 months, returned to baseline during washout and remained stable during subsequent IVIg treatment. Our findings confirm and extend those obtained by Dodel et al. [Dodel, R.C., Du, Y., Depboylu, C., Hampel, H., Frolich, L., Haag, A., Hemmeter, U., Paulsen, S., Teipel, S.J., Brettschneider, S., Spottke, A., Nolker, C., Moller, H.J., Wei, X., Farlow, M., Sommer, N., Oertel, W.H., 2004. Intravenous immunoglobulins containing antibodies against beta-amyloid for the treatment of Alzheimer's disease. J. Neurol. Neurosurg. Psychiatry 75, 1472-1474] from a 6-month trial of IVIg in 5 AD patients and justify further studies of IVIg for treatment of AD.

Natural human antibodies to amyloid beta peptide.

Properties of human, natural anti-Abeta antibodies and commercially available intravenous immunoglobulin (IVIg) have been examined in light of the beneficial effects of passive immunotherapy with IVIg for patients with mild to moderate Alzheimer's disease (AD). Anti-Abeta antibodies in IVIg recognize conformation-specific epitopes as well as linear epitopes from different regions of the Abeta peptide. Anti-Abeta antibodies in circulation, especially those with high avidity, are often masked by ligands and the avidity of these antibodies increases upon dissociation of the bound ligands from the antibodies. Such natural anti-Abeta antibodies have the capacity to prevent Abeta oligomer-induced neurotoxicity in N2A neuroblastoma cells. This neuro-protective effect may reflect the therapeutic potential of the natural anti-Abeta antibodies found in IVIg for the treatment of patients with AD.

Catalytic antibodies to amyloid beta peptide in defense against Alzheimer disease.

Immunoglobulins (Igs) that bind amyloid beta peptide (Abeta) are under clinical trials for immunotherapy of Alzheimer disease (AD). We have identified IgMs and recombinant Ig fragments that hydrolyze Abeta. Hydrolysis of peripheral Abeta by the IgMs may induce increased Abeta release from the brain. The catalytic IgMs are increased in AD patients, presumably reflecting a protective autoimmune response. Reduced Abeta aggregation and neurotoxicity attributable to the catalytic function were evident. These findings provide a foundation for development of catalytic Igs for AD immunotherapy.

Autoantibody-catalyzed hydrolysis of amyloid beta peptide.

We describe IgM class human autoantibodies that hydrolyze amyloid beta peptide 1-40 (Abeta40). A monoclonal IgM from a patient with Waldenström's macroglobulinemia hydrolyzed Abeta40 at the Lys-28-Gly-29 bond and Lys-16-Ala-17 bonds. The catalytic activity was inhibited stoichiometrically by an electrophilic serine protease inhibitor. Treatment with the catalytic IgM blocked the aggregation and toxicity of Abeta40 in neuronal cell cultures. IgMs purified from the sera of patients with Alzheimer disease (AD) hydrolyzed Abeta40 at rates superior to IgMs from age-matched humans without dementia. IgMs from non-elderly humans expressed the least catalytic activity. The reaction rate was sufficient to afford appreciable degradation at physiological Abeta and IgM concentrations found in peripheral circulation. Increased Abeta concentrations in the AD brain are thought to induce neurodegenerative effects. Peripheral administration of Abeta binding antibodies has been suggested as a potential treatment of AD. Our results suggest that catalytic IgM autoantibodies can help clear Abeta, and they open the possibility of using catalytic Abs for AD immunotherapy.

Human plasma semicarbazide sensitive amine oxidase (SSAO), beta-amyloid protein and aging.

Semicarbazide sensitive amine oxidase (SSAO) metabolizes oxidative deamination of primary aromatic and aliphatic amines. The final products of its catalysis, ammonia, hydrogen peroxide (H2O2) and the corresponding aldehyde, may contribute to diseases involving vascular degeneration. SSAO is selectively expressed in blood vessels in the brain, but is also present in blood plasma. We have previously reported that membrane-bound SSAO is overexpressed in the cerebrovascular tissue of Alzheimer's disease (AD) patients. The aim of the present work is to study whether the circulating SSAO is also altered in this neurodegenerative disease. SSAO activity was determined in plasma of control cases (n = 23) and patients suffering sporadic Alzheimer dementia, distributed according to the Global Deterioration Scale (GDS): mild (n = 33), moderate (n = 14), moderate-severe (n = 15) and severe dementia (n = 19). Results show a clear increase of plasma SSAO activity (p < 0.001) in moderate-severe and severe AD patients, with patient age being an independent correlative factor. However, plasma SSAO activity was not altered in AD patients with mild or moderate dementia compared to controls. beta-Amyloid (Abeta) (40-42) immunoreactivity in plasma samples was also determined, and no correlation was observed between Abeta 40-42 levels and the severity of the dementia or the plasma SSAO activity. Our results suggest that an increase in circulating SSAO activity could contribute to oxidative stress and vascular damage in advanced Alzheimer's disease.

The immune system, amyloid-beta peptide, and Alzheimer's disease.

In this review, the case is made that amyloid-beta peptide in the brain of patients with Alzheimer's disease is a primary cause of the disease and that immunotherapy directed against this peptide has the potential to halt and/or reverse disease progression. This supposition is supported by the capacity of anti-beta-amyloid peptide antibodies to prevent or reverse the disease in mouse models of Alzheimer's disease. Furthermore, preliminary results obtained in a small number of patients with Alzheimer's disease are consistent with the observations made in the mouse model of this disease. We review the relationship between the immune system, amyloid-beta peptide, and Alzheimer's disease and the progress made in applying immunotherapy to patients with Alzheimer's disease.

Evolution of B-cell clonal expansions with age.

B-cell clonal expansions (BCE) in young mice are transient, detectable for less than 4 weeks. In contrast, BCE in old mice persist more than 2 months. The greater persistence of BCE in old mice does not appear to be due to the age of the host as the survival of phenyloxazolone chicken serum albumin-induced BCE in most old mice was shorter than in young mice. This raises the possibility that persistent BCE seen in old mice develop over time from transient BCE present earlier in life. To test this hypothesis, young C57BL/6 mice were immunized with hen egg lysozyme (HEL) during the first year of life. By 28 months of age, the majority of these mice had developed a benign, persistent BCE associated with a HEL-specific serum mIg. We also investigated whether benign, persistent BCE, present in 18-month-old mice, can evolve into B-cell lymphomas. We observed that four of eight C57BL/6 mice that survived to 29 months of age had developed diffuse large cell lymphomas. In three of these mice, this diagnosis was made by microscopic analysis of the lymphoid organs. In one mouse, a macroscopic lymphoma was present that permitted us to demonstrate that the IgH mRNA CDR3 length and sequence in the malignant lymphoma was derived from a persistent BCE present 11 months earlier. Together these observations are consistent with the hypothesis that stepwise accumulation of genetic alterations combined with Darwinian selection underlies the evolution of B cells from transient BCE in young mice into persistent BCE, serum mIg, and B-cell lymphomas observed in older mice.

Impaired rearrangement of IgH V to DJ segments in bone marrow Pro-B cells from old mice.

There are fewer bone marrow Pre-B cells in old compared to young mice. We have demonstrated both decreased rearrangement of the V to DJ IgH gene segments and low levels of VH germline transcripts in Pro-B cells, the precursors of Pre-B cells, from old compared to young mice. However, there was no difference in the level of RAG-mRNA in purified Pro-B cells from old and young mice. Consistent with the prior reports that fewer bone marrow emigrants enter the peripheral B cell populations of old than young mice, we identified fewer transitional B cells in the blood, as well as the spleen, of old than young mice. Association of impaired IgH rearrangement with a decreased number of transitional B cells in old mice was supported by finding that the percentage and number of transitional B cells expressing rearranged IgH and IgL transgenes, which do not require rearrangement of their endogenous IgH gene segments, were comparable in old and young mice. In contrast, the percentage and number of transitional B cells in these Ig-transgenic mice, which escaped allelic exclusion and have rearranged endogenous IgH gene segments, showed an age-associated decline similar to that seen in wild type mice. These data are consistent with the view that impaired V to DJ rearrangement contributes to the decreased levels of bone marrow Pre-B cells as well as the decreased levels of transitional B cells in the periphery.

Oligoclonal expansions of antigen-specific CD8+ T cells in aged mice.

Oligoclonal T cell expansions (TCE) are common in old humans and mice. It is not known whether an Ag-specific response becomes more oligoclonal with age, and, if so, how this might alter biological responses or compromise the immune response, thus contributing to the immunodeficiency of aging. We used a tumor antigen response to study these questions. Early on, antigen reactive T cell numbers at the site of tumor injection were lower and clonally more restricted in old mice. Subsequently, long-term oligoclonal TCE emerged in the blood and spleen of old mice. IL-15 was not necessary for development of TCE in the blood. Overall, the data pointed to a dysregulated immune response in old mice, perhaps due to lack of optimal IL-2 and CD4 help at the earliest stages and a lack of an efficient local peritoneal CTL response. This was associated with a deficient humoral response and, likely, persistence of tumor cells or tumor antigens. Perhaps the spleen is the site of persistence which explains clonal TCE observed primarily in PBL and spleen. The TCE appear to be inefficient as they are often anergic. As a result an occasional peritoneal or splenic tumor may arise in old mice.

Tumor antigen drives a persistent oligoclonal expansion of CD8+ T cells in aged mice.

Oligoclonal T cell expansions (TCE) are common in old humans and mice, but it is not known whether the T cell response to a specific antigen is more restricted in old vs. young animals. Herein, we describe an enhanced and prolonged response of tumor antigen-specific CD8 cells in old mice identified by K(d)/peptide tetramers and Vbeta10 staining. At the onset of the response CD8 T cell numbers and Vbeta10+CD8+ cells at the site of tumor injection were lower in old mice, hinting that control of initial tumor growth may not be optimal. As further evidence of a dysregulated response in old mice, antibody titers to the tumor were deficient and the CD8 tumor antigen-specific response was greater and more prolonged in the blood and spleen. Old mice selected a more oligoclonal TCR repertoire based on TCRbeta chain CDR3 length analysis and sequences. Persistent expansions of Vbeta10+CD8+ cells in old mice had memory/activation phenotypes. This induced tumor antigen-specific response may represent a model for the spontaneous TCE observed with aging and demonstrates that the CD8 response to a defined peptide/MHC antigen is indeed more oligoclonal in old mice.

Patients with Alzheimer disease have lower levels of serum anti-amyloid peptide antibodies than healthy elderly individuals.

Active immunization with the human amyloid peptide (Abeta42) or passive immunization with anti-Abeta42 antibodies protects mice that express a mutant human amyloid precursor protein (APP) transgene from cerebral amyloid deposits. If anti-Abeta42 antibodies protect APP-transgenic mice, a model of Alzheimer's disease (AD), a high titer of anti-Abeta42 antibodies may protect humans from AD. The titer of anti-Abeta42 antibodies in serum from individuals with and without late onset AD was measured using an ELISA. The titer of Ig (IgM, IgG and IgA) and IgG anti-Abeta42 peptide antibodies was significantly higher in serum from elderly controls than AD patients. Furthermore, IgG but not Ig anti-Abeta42 antibodies distinguished sera from AD patients and elderly controls that did not have the apolipoprotein E4 allele. The low titer of anti-Abeta42 antibodies in AD patients does not reflect the well-established, age-associated defect in the antibody response to most protein antigens, as there was no positive correlation between the serum titer of anti-Abeta42 antibodies and anti-influenza hemagglutinin antibodies induced by influenza vaccine in elderly humans. The lower titer of serum anti-Abeta42 peptide antibodies in AD patients may reflect the reported specific impairment of helper T cell activity for B cells that produce anti-amyloid-beta42 peptide antibodies in APP-transgenic mice.