The rockefeller university

Neuronal networks in the prefrontal cortex mediate the highest levels of cognitive processing and decision making, and the capacity to perform these functions is among the cognitive features most vulnerable to aging. Despite much research, the neurobiological basis of age-related compromised prefrontal function remains elusive. Many investigators have hypothesized that exposure to stress may accelerate cognitive aging, though few studies have directly tested this hypothesis and even fewer have investigated a neuronal basis for such effects. It is known that in young animals, stress causes morphological remodeling of prefrontal pyramidal neurons that is reversible. The present studies sought to determine whether age influences the reversibility of stress-induced morphological plasticity in rat prefrontal neurons. We hypothesized that neocortical structural resilience is compromised in normal aging. To directly test this hypothesis we used a well characterized chronic restraint stress paradigm, with an additional group allowed to recover from the stress paradigm, in 3-, 12-, and 20-month-old male rats. In young animals, stress induced reductions of apical dendritic length and branch number, which were reversed with recovery; in contrast, middle-aged and aged rats failed to show reversible morphological remodeling when subjected to the same stress and recovery paradigm. The data presented here provide evidence that aging is accompanied by selective impairments in long-term neocortical morphological plasticity.

The Mediator subunit MED1/TRAP220/DRIP205/PBP interacts directly with many nuclear receptors and was long thought to be responsible for tethering Mediator to peroxisome proliferator-activated receptor (PPAR)-responsive promoters. However, it was demonstrated recently that PPAR gamma can recruit Mediator by MED1-independent mechanisms. Here, we show that target gene activation by ectopically expressed PPAR gamma and PPAR gamma is independent of MED1. Consistent with this finding, recruitment of PPAR gamma, MED6, MED8, TATA box-binding protein (TBP), and RNA polymerase II (RNAPII) to the enhancer and proximal promoter of the PPAR gamma target gene Fabp4 is also independent of MED1. Using a small interfering RNA (siRNA)-based approach, we identify MED14 as a novel critical Mediator component for PPAR gamma-dependent transactivation, and we demonstrate that MED14 interacts directly with the N terminus of PPAR gamma in a ligand-independent manner. Interestingly, MED14 knockdown does not affect the recruitment of PPAR gamma, MED6, and MED8 to the Fabp4 enhancer but does reduce their occupancy of the Fabp4 proximal promoter. In agreement with the necessity of MED14 for PPAR gamma transcriptional activity, we show that knockdown of MED14 impairs adipogenesis of 3T3-L1 cells. Thus, MED14 constitutes a novel anchoring point between Mediator and the N-terminal domain of PPAR gamma that is necessary for functional PPAR gamma-mediated recruitment of Mediator and transactivation of PPAR gamma subtype-specific target genes.

We and others frequently have noted serum potassium levels of 8.0 +/- 0.85 mEq/L or greater in laboratory mice; this concentration has even been published as the upper limit of a 'normal' reference range. However, if bone fide, this potassium concentration would be incompatible with life in all species. We investigated conditions frequently encountered in the research setting to distinguish artifactual from true hyperkalemia. Variables evaluated included site of collection, time allowed for clot formation before serum separation, time elapsed between collection and analysis of samples collected in a serum separator tube, precollection method of anesthesia, and euthanasia technique. Serum potassium was measured from 75 C57BL/6NTac 10-wk-old female mice and divided into at least 5 mice per variable. Animals were euthanized by exsanguination immediately after terminal CO2 or ketamine xylazine (KX) administration. Mice euthanized with CO2 had higher mean serum potassium (7.0 +/- 0.5 mEq/L) and range serum potassium (6.0 to 8.1 mEq/L) than did KX-treated mice. CO2 inhalation resulted in significantly lower blood pH (6.9 +/- 0.1), higher pCO(2) (153.3 +/- 38.8 mm Hg), and higher lactate levels (3.9 +/- 0.9 mmol/L) than did KX anesthesia followed by exsanguination. These results suggest that antemortem respiratory acidosis from CO2 administration causes artifactual hyperkalemia in mice. Therefore, blood collection under KX anesthesia is preferable over CO2 inhalation to obtain accurate potassium values from mice.

The zinc finger antiviral protein (ZAP) is a host factor with potent antiviral activity when overexpressed in cells. ZAP blocks replication of the prototype alphavirus Sindbis virus (SINV) at a step at or before translation of the incoming viral genome. The mechanism of ZAP anti-SINV activity and the determinants of its antiviral function, however, have not been defined. Here, we have identified a dominant negative inhibitor of human ZAP. Rat ZAP with a cysteine-to-arginine mutation at position 88 (rZAPC88R), previously reported as a nonfunctional form of ZAP, increases SINV growth in cells. These results led us to discover a previously undetectable pool of endogenous functional ZAP within human cells. Investigation of the mechanism of dominant negative inhibition, combined with a comprehensive mutational analysis of the antiviral factor, revealed that homotypic associations are required for ZAP function in limiting SINV propagation.

Women and people of color continue to be underrepresented among biomedical researchers to an alarming degree. Research interest and subsequent productivity have been shown to be affected by the research training environment through the mediating effects of research self-efficacy. This article presents the findings of a study to determine whether a short-term research training program coupled with an efficacy enhancing intervention for novice female biomedical scientists of diverse racial backgrounds would increase their research self-efficacy beliefs. Forty-three female biomedical scientists were randomized into a control or intervention group and 15 men participated as a control group. Research self-efficacy significantly increased for women who participated in the self-efficacy intervention workshop. Research self-efficacy within each group also significantly increased following the short-term research training program, but cross-group comparisons were not significant. These findings suggest that educational interventions that target sources of self-efficacy and provide domain-specific learning experiences are effective at increasing research self-efficacy for women and men. Further studies are needed to determine the longitudinal outcomes of this effort.

Most HIV-infected individuals develop antibodies to the gp120 and gp41 components of the viral spike; however, only a fraction of these individuals mount a broadly neutralizing serum response against HIV. We have cloned anti-HIV antibodies from the memory B-cell compartment of six individuals with variable viral loads and high titers of broadly neutralizing antibodies. Here, we report on the features of the anti-gp41 response in these patients. Competition experiments with previously characterized antibodies targeting defined epitopes on the gp41 ectodomain showed antibodies directed against the "immunodominant region" (cluster I), the carboxy-terminal heptad repeat (cluster II), and the membrane-proximal external region (cluster IV). On the other hand, antibodies directed against the amino-terminal part of the molecule, including the fusion peptide, polar region, and the N-terminal heptad repeat, were not detected. When all patients' data were combined, unique B-cell clones targeting cluster I, II, and IV accounted for 32%, 49%, and 53% of all anti-gp41-reactive B cells, respectively; therefore, no single region was truly immunodominant. Finally, although we found no new neutralizing epitopes or HIV-1-neutralizing activity by any of the gp41 antibodies at concentrations of up to 50 mu g/ml, high concentrations of 7 out of 15 anti-cluster I antibodies neutralized tier 2 viruses.

Acquisition and quantitative analysis of high resolution images of dendritic spines are challenging tasks but are necessary for the study of animal models of neurological and psychiatric diseases. Currently available methods for automated dendritic spine detection are for the most part customized for 2D image slices, not volumetric 3D images. In this work, a fully automated method is proposed to detect and segment dendritic spines from 3D confocal microscopy images of medium-sized spiny neurons (MSNs). MSNs constitute a major neuronal population in striatum, and abnormalities in their function are associated with several neurological and psychiatric diseases. Such automated detection is critical for the development of new 3D neuronal assays which can be used for the screening of drugs and the studies of their therapeutic effects. The proposed method utilizes a generalized gradient vector flow (GGVF) with a new smoothing constraint and then detects feature points near the central regions of dendrites and spines. Then, the central regions are refined and separated based on eigen-analysis and multiple shape measurements. Finally, the spines are segmented in 3D space using the fast marching algorithm, taking the detected central regions of spines as initial points. The proposed method is compared with three popular existing methods for centerline extraction and also with manual results for dendritic spine detection in 3D space. The experimental results and comparisons show that the proposed method is able to automatically and accurately detect, segment, and quantitate dendritic spines in 3D images of MSNs. (C) 2010 Elsevier Inc. All rights reserved.

This Letter describes the current most precise measurement of the W boson pair production cross section and most sensitive test of anomalous WW gamma and WWZ couplings in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV. The WW candidates are reconstructed from decays containing two charged leptons and two neutrinos. Using data collected by the CDF II detector from 3: 6 fb(-1) of integrated luminosity, a total of 654 candidate events are observed with an expected background of 320 +/- 47 events. The measured cross section is sigma(p (p) over bar -> W+W- +X) = 12.1 +/- 0.9(stat)(-1.4)(+1.6)(syst) pb, which is in good agreement with the standard model prediction. The same data sample is used to place constraints on anomalous WW gamma and WWZ couplings.