Interactions between the NR2B receptor and CaMKII modulate synaptic plasticity and spatial learning.

The NR2B subunit of the NMDA receptor interacts with several prominent proteins in the postsynaptic density, including calcium/calmodulin-dependent protein kinase II (CaMKII). To determine the function of these interactions, we derived transgenic mice expressing a ligand-activated carboxy-terminal NR2B fragment (cNR2B) by fusing this fragment to a tamoxifen (TAM)-dependent mutant of the estrogen receptor ligand-binding domain LBD(G521R). Here, we show that induction by TAM allows the transgenic cNR2B fragment to bind to endogenous CaMKII in neurons. Activation of the LBD(G521R)-cNR2B transgenic protein in mice leads to the disruption of CaMKII/NR2B interactions at synapses. The disruption decreases Thr286 phosphorylation of alphaCaMKII, lowers phosphorylation of a key CaMKII substrate in the postsynaptic membrane (AMPA receptor subunit glutamate receptor 1), and produces deficits in hippocampal long-term potentiation and spatial learning. Together our results demonstrate the importance of interactions between CaMKII and NR2B for CaMKII activity, synaptic plasticity, and learning

Using Electronic Drug Monitor Feedback to Improve Adherence to Antiretroviral Therapy Among HIV-Positive Patients in China

Effective antiretroviral therapy (ART) requires excellent adherence. Little is known about how to improve ART adherence in many HIV/AIDS-affected countries, including China. We therefore assessed an adherence intervention among HIV-positive patients in southwestern China. Eighty subjects were enrolled and monitored for 6 months. Sixty-eight remaining subjects were randomized to intervention/control arms. In months 7–12, intervention subjects were counseled using EDM feedback; controls continued with standard of care. Among randomized subjects, mean adherence and CD4 count were 86.8 vs. 83.8% and 297 vs. 357 cells/μl in intervention vs. control subjects, respectively. At month 12, among 64 subjects who completed the trial, mean adherence had risen significantly among intervention subjects to 96.5% but remained unchanged in controls. Mean CD4 count rose by 90 cells/μl and declined by 9 cells/μl among intervention and control subjects, respectively. EDM feedback as a counseling tool appears promising for management of HIV and other chronic diseases.Boston University and the Office of Health and Nutrition of the United States Agency for International Development (GHS-A-00-03-00030-00); World Health Organization; United States Centers for Disease Control; National Institutes of Health, National Institute of Allergy and Infectious Diseases (K23 AI 62208); Mid-Career Mentoring Award (K24 RR020300

Human immunodeficiency virus type 1 efficiently binds to human fetal astrocytes and induces neuroinflammatory responses independent of infection

<p>Abstract</p> <p>Background</p> <p>HIV-1 infects human astrocytes <it>in vitro </it>and <it>in vivo </it>but the frequency of infected cells is low and its biological significance is unknown. In studies <it>in vitro</it>, recombinant gp120 alone can induce profound effects on astrocyte biology, suggesting that HIV-1 interaction with astrocytes and its functional consequences extend beyond the limited levels of infection in these cells. Here we determined the relative efficiencies of HIV-1 binding and infection in human fetal astrocytes (HFA), mainly at the single cell level, using HIV-1 tagged with green fluorescence protein (GFP)-Vpr fusion proteins, termed HIV-GFP, to detect virus binding and HIV-1 expressing Rev and NefGFP fusion proteins to detect productive infection.</p> <p>Results</p> <p>Essentially all HFA in a population bound HIV-GFP specifically and independently of CCR5 and CXCR4. The dynamics of this binding at 37°C resembled binding of an HIV fusion mutant to CD4-positive cells, indicating that most of HIV-GFP arrested infection of HFA at the stage of virus-cell fusion. Despite extensive binding, only about 1% of HFA were detectably infected by HIV-RevGFP or HIV-NefGFP, but this proportion increased to the majority of HFA when the viruses were pseudotyped with vesicular stomatitis virus envelope glycoprotein G, confirming that HFA impose a restriction upon HIV-1 entry. Exposure of HFA to HIV-1 through its native proteins rapidly induced synthesis of interleukin-6 and interleukin-8 with increased mRNA detected within 3 h and increased protein detected within 18 h of exposure.</p> <p>Conclusion</p> <p>Our results indicate that HIV-1 binding to human astrocytes, although extensive, is not generally followed by virus entry and replication. Astrocytes respond to HIV-1 binding by rapidly increased cytokine production suggesting a role of this virus-brain cell interaction in HIV-1 neuropathogenesis.</p

Mechanical Behavior of Microelectromechanical Microshutters

A custom micro-mechanical test system was constructed using off-the-shelf components to characterize the mechanical properties of microshutters. Microshutters are rectangular microelectromechanical apertures which open and close about a narrow torsion bar hinge. Displacement measurements were verified using both capacitive and digital image correlation techniques. Repeatable experiments on Si3N4 cantilever beams verified that the test system operates consistently. Using beam theory, the modulus of elasticity of the low stress Si3N4 was approximately 150 GPa, though significant uncertainty exists for this measurement due primarily to imprecise knowledge of the cantilever thickness. Tests conducted on microshutter arrays concluded that reducing the Si3N4 thickness from 250 nm to 500 nm reduces the torsional stiffness by a factor of approximately four. This is in good agreement with analytical and finite element models of the microshutters

Lithographic processing of polymers using plasma-generated electron beams

Includes bibliographical references.Pattern definition in polymer films is achieved using electron beams generated in soft vacuum (0.05-0.50 torr) glow discharges either on a continuous or pulsed (20-100 ns) basis. With the continuous- mode electron beam, 7- µm transmission mask features are replicated in both polymethyl methacrylate (PMMA) and polyimide resists. Using a pulsed electron-beam submicron (~0.5 µm) features are transferred from an electron-transmitting stencil mask into the PMMA. The soft-vacuum pulsed electron beam is also eminently suited for polymer stabilization. Pulsed electron-beam hardening of 0.05-3.5- µm-thick AZ-type and MacDermid resist patterns is also demonstrated with hardened resist patterns stable to temperatures between 200° and 350°C. The demonstrated replication and pattern stabilization technique may be applicable in microelectronics packaging lithography where the resist thickness is substantial, linewidths are 1-10 µm, and registration requirements are less stringent.This work was supported by the National Science Foundation (Quantum Electrorncs Waves and Beams) under Contract No. ECS-8815051, the Colorado Advanced Technology Institute, the Hewlett Packard Corporation, the Applied Electron Corporation, the IBM Corporation, and by MIS Buckbee-Mears of St. Paul, MN

Developmental Exposure to Perchlorate Alters Synaptic Transmission in Hippocampus of the Adult Rat

BackgroundPerchlorate is an environmental contaminant that blocks iodine uptake into the thyroid gland and reduces thyroid hormones. This action of perchlorate raises significant concern over its effects on brain development.ObjectivesThe purpose of this study was to evaluate neurologic function in rats after developmental exposure to perchlorate.MethodsPregnant rats were exposed to 0, 30, 300, or 1,000 ppm perchlorate in drinking water from gestational day 6 until weaning. Adult male offspring were evaluated on a series of behavioral tasks and neurophysiologic measures of synaptic function in the hippocampus.ResultsAt the highest perchlorate dose, triiodothyronine (T3) and thyroxine (T4) were reduced in pups on postnatal day 21. T4 in dams was reduced relative to controls by 16%, 28%, and 60% in the 30-, 300-, and 1,000-ppm dose groups, respectively. Reductions in T4 were associated with increases in thyroid-stimulating hormone in the high-dose group. No changes were seen in serum T3. Perchlorate did not impair motor activity, spatial learning, or fear conditioning. However, significant reductions in baseline synaptic transmission were observed in hippocampal field potentials at all dose levels. Reductions in inhibitory function were evident at 300 and 1,000 ppm, and augmentations in long-term potentiation were observed in the population spike measure at the highest dose.ConclusionsDose-dependent deficits in hippocampal synaptic function were detectable with relatively minor perturbations of the thyroid axis, indicative of an irreversible impairment in synaptic transmission in response to developmental exposure to perchlorate