ABSTRACT
Alzheimer's disease (AD) is associated with aberrant neuronal activity, which is believed to critically determine disease symptoms. How these activity alterations emerge, how stable they are over time, and whether cellular activity dynamics are affected by the amyloid plaque pathology remains incompletely understood. We here repeatedly recorded the activity from identified neurons in cortex of awake APPPS1 transgenic mice over four weeks during the early phase of plaque deposition using in vivo two-photon calcium imaging. We found that aberrant activity during this stage largely persisted over the observation time. Novel highly active neurons slowly emerged from former intermediately active neurons. Furthermore, activity fluctuations were independent of plaque proximity, but aberrant activity was more likely to persist close to plaques. These results support the notion that neuronal network pathology observed in models of cerebral amyloidosis is the consequence of persistent single cell aberrant neuronal activity, a finding of potential diagnostic and therapeutic relevance for AD.
Subject(s)
Alzheimer Disease/physiopathology , Neurons/physiology , Plaque, Amyloid/physiopathology , Animals , Disease Models, Animal , Female , Male , Mice , Mice, Transgenic , Neurons/pathologyABSTRACT
The quasi-two dimensional Coulomb interaction potential in transition metal dichalcogenides is determined using the Kohn-Sham wave functions obtained fromab initiocalculations. An effective form factor is derived that accounts for the finite extension of the wave functions in the direction perpendicular to the material layer. The resulting Coulomb matrix elements are used in microscopic calculations based on the Dirac Bloch equations yielding an efficient method to calculate the band gap and the opto-electronic material properties in different environments and under various excitation conditions.
ABSTRACT
Dengue Virus (DENV) is the most prevalent global arbovirus, yet despite an increasing burden to health care there are currently no therapeutics available to treat infection. A potential target for antiviral drugs is the two-component viral protease NS2B-NS3pro, which is essential for viral replication. Interactions between the two components have been investigated here by probing the effect on the rate of enzyme catalysis of key mutations in a mobile loop within NS2B that is located at the interface of the two components. Steady-state kinetic assays indicated that the mutations greatly affect catalytic turnover. However, single turnover and fluorescence experiments have revealed that the mutations predominantly affect product release rather than substrate binding. Fluorescence analysis also indicated that the addition of substrate triggers a near-irreversible change in the enzyme conformation that activates the catalytic centre. Based on this mechanistic insight, we propose that residues within the mobile loop of NS2B control product release and present a new target for design of potent Dengue NS2B-NS3 protease inhibitors.
Subject(s)
Dengue Virus/chemistry , Oligopeptides/chemistry , Serine Endopeptidases/chemistry , Viral Nonstructural Proteins/chemistry , Amino Acid Substitution , Binding Sites , Biocatalysis , Cloning, Molecular , Crystallography, X-Ray , Dengue Virus/enzymology , Escherichia coli/genetics , Escherichia coli/metabolism , Gene Expression , Genetic Vectors/chemistry , Genetic Vectors/metabolism , Kinetics , Models, Molecular , Mutation , Oligopeptides/metabolism , Protein Binding , Protein Conformation, alpha-Helical , Protein Conformation, beta-Strand , Protein Interaction Domains and Motifs , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Serine Endopeptidases/genetics , Serine Endopeptidases/metabolism , Substrate Specificity , Thermodynamics , Viral Nonstructural Proteins/genetics , Viral Nonstructural Proteins/metabolismABSTRACT
The loss of synapses is a strong histological correlate of the cognitive decline in Alzheimer's disease (AD). Amyloid ß-peptide (Aß), a cleavage product of the amyloid precursor protein (APP), exerts detrimental effects on synapses, a process thought to be causally related to the cognitive deficits in AD. Here, we used in vivo two-photon microscopy to characterize the dynamics of axonal boutons and dendritic spines in APP/Presenilin 1 (APP(swe)/PS1(L166P))-green fluorescent protein (GFP) transgenic mice. Time-lapse imaging over 4 weeks revealed a pronounced, concerted instability of pre- and postsynaptic structures within the vicinity of amyloid plaques. Treatment with a novel sulfonamide-type γ-secretase inhibitor (GSI) attenuated the formation and growth of new plaques and, most importantly, led to a normalization of the enhanced dynamics of synaptic structures close to plaques. GSI treatment did neither affect spines and boutons distant from plaques in amyloid precursor protein/presenilin 1-GFP (APPPS1-GFP) nor those in GFP-control mice, suggesting no obvious neuropathological side effects of the drug.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Dendritic Spines/pathology , Plaque, Amyloid/drug therapy , Presynaptic Terminals/pathology , Quinolines/pharmacology , Sulfonamides/pharmacology , Amyloid beta-Protein Precursor/genetics , Animals , Enzyme Inhibitors/pharmacology , Male , Mice , Mice, Transgenic , Microscopy, Fluorescence, Multiphoton , Plaque, Amyloid/pathology , Presenilin-1/genetics , Quinolines/therapeutic use , Sulfonamides/therapeutic useABSTRACT
BACKGROUND: This phase I dose-escalation study was designed to determine the maximum tolerated dose (MTD) and recommended dose of cetuximab administered on an every-second-week schedule to patients with metastatic colorectal cancer, on the basis of safety, pharmacokinetic and pharmacodynamic evaluation. PATIENTS AND METHODS: The study comprised two parts: a 6-week cetuximab monotherapy dose-escalation phase and a subsequent combination therapy phase, during which patients received cetuximab, at the same dose/schedule as in the monotherapy phase, followed by irinotecan plus infusional 5-fluorouracil/folinic acid (FOLFIRI). Patients in the control group received cetuximab as a 400 mg/m(2) initial dose, then 250 mg/m(2)/week and in the dose-escalation group, at 400-700 mg/m(2), every second week. RESULTS: Sixty-two patients were included in the study. The MTD of cetuximab administered on an every-second-week schedule was not reached. The safety profiles were similar across all groups. Response rates in the cetuximab monotherapy and combination therapy phases were 15% and 42%, respectively. Trough levels for the 500, 600 mg/m(2) and standard weekly regimens were comparable. CONCLUSION: Cetuximab can be safely administered once every second week at doses between 400 and 700 mg/m(2), with 500 mg/m(2) being the most convenient and feasible dose for future studies.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/pharmacokinetics , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Colorectal Neoplasms/drug therapy , Colorectal Neoplasms/secondary , Aged , Antibodies, Monoclonal/administration & dosage , Antibodies, Monoclonal, Humanized , Camptothecin/administration & dosage , Camptothecin/analogs & derivatives , Cetuximab , Colorectal Neoplasms/metabolism , Dose-Response Relationship, Drug , ErbB Receptors/metabolism , Female , Fluorouracil/administration & dosage , Humans , Immunoenzyme Techniques , Irinotecan , Leucovorin/administration & dosage , Male , Maximum Tolerated Dose , Middle Aged , Survival Rate , Tissue Distribution , Treatment OutcomeSubject(s)
Patient Education as Topic/methods , Physician-Patient Relations , Psoriasis/psychology , Sick Role , Adult , Female , Humans , MaleABSTRACT
This paper describes the detection of viral particles in a human amnion cell line (FL). These particles belong to the group of type D retroviruses, because of their characteristic morphology, their major antigenic determinants, and the presence of particle-associated Mg++-preferring RNA-dependent DNA polymerase. In addition to budding and mature type D virus particles, intracytoplasmic type A structures have also been found. Immunological analysis provided evidence of cross-reactivity between the particles described and the Mason-Pfizer monkey virus as well as type D retroviruses from other human cell lines (PMF, HEp-2). Particles isolated from FL cell medium were shown to infect type D virus-susceptible human TU 197 cells.
