The rockefeller university

An isospectral matrix reduction is a procedure that reduces the size of a matrix while maintaining its eigenvalues up to a known set. As to not violate the fundamental theorem of algebra, the reduced matrices have rational functions as entries. Because isospectral reductions can preserve the spectrum of a matrix, they are fundamentally different from say the restriction of a matrix to an invariant subspace. We show that the notion of pseudospectrum can be extended to a wide class of matrices with rational function entries and that the pseudospectrum of such matrices shrinks with isospectral reductions. Hence, the eigenvalues of a reduced matrix are more robust to entry-wise perturbations than the eigenvalues of the original matrix. Moreover, the isospectral reductions considered here are more general than those considered elsewhere. We also introduce the notion of an inverse pseudospectrum (or pseudoresonances), which indicates how stable the poles of a rational function valued matrix are to entry-wise perturbations. Illustrations of these concepts are given for mass-spring networks. Copyright (c) 2014 John Wiley & Sons, Ltd.

Intracellular ISG15 is an interferon (IFN)-alpha/beta-inducible ubiquitin-like modifier which can covalently bind other proteins in a process called ISGylation; it is an effector of IFN-alpha/beta-dependent antiviral immunity in mice(1-4). We previously published a study describing humans with inherited ISG15deficiency but without unusually severe viral diseases(5). We showed that these patients were prone to mycobacterial disease and that human ISG15 was non-redundant as an extracellular IFN-gamma-inducing molecule. We show here that ISG15-deficient patients also display unanticipated cellular, immunological and clinical signs of enhanced IFN-alpha/beta immunity, reminiscent of the Mendelian autoinflammatory interferonopathies Aicardi-Goutieres syndrome and spondyloenchondrodysplasia(6-9). We further show that an absence of intracellular ISG15 in the patients' cells prevents the accumulation of USP18(10,11), a potent negative regulator of IFN-alpha/beta signalling, resulting in the enhancement and amplification of IFN-alpha/beta responses. Human ISG15, therefore, is not only redundant for antiviral immunity, but is a key negative regulator of IFN-alpha/beta immunity. In humans, intracellular ISG15 is IFN-alpha/beta-inducible not to serve as a substrate for ISGylation-dependent antiviral immunity, but to ensure USP18-dependent regulation of IFN-alpha/beta and prevention of IFN-alpha/beta-dependent autoinflammation.

We developed a strategy for identifying positions in G protein-coupled receptors that are amenable to bioorthogonal modification with a peptide epitope tag under cell culturing conditions. We introduced the unnatural amino acid p-azido-l-phenylalanine (azF) into human CC chemokine receptor 5 (CCR5) at site-specific amber codon mutations. We then used strain-promoted azide-alkyne [3+2] cycloaddition to label the azF-CCR5 variants with a FLAG peptide epitope-conjugated aza-dibenzocyclooctyne (DBCO) reagent. A microtiter plate-based sandwich fluorophore-linked immunosorbent assay was used to probe simultaneously the FLAG epitope and the receptor using infrared dye-conjugated antibodies so that the extent of DBCO incorporation, corresponding nominally to labeling efficiency, could be quantified ratiometrically. The extent of incorporation of DBCO at the various sites was evaluated in the context of a recent crystal structure of maraviroc-bound CCR5. We observed that labeling efficiency varied dramatically depending on the topological location of the azF in CCR5. Interestingly, position 109 in transmembrane helix 3, located in a hydrophobic cavity on the extracellular side of the receptor, was labeled most efficiently. Because the bioorthogonal labeling and detection strategy described might be used to introduce a variety of different peptide epitopes or fluorophores into engineered expressed receptors, it might prove to be useful for a wide range of applications, including single-molecule detection studies of receptor trafficking and signaling mechanism.

Shiga toxin-producing Escherichia coli (STEC) O157:H7 strains (isolated by cattle's faeces and a reference strain, EDL933), were inoculated into pasteurized milk (10(2) and 10(3) cells. mL(-1)) to prepare the Minas frescal cheese. As control was used uninfected milk. Physicochemical and microbiological analyses were performed to milk and elaborated cheese. The O157:H7 strains were quantified in the stages of cheese processing and during 0, 2, 4, 5, 7, 10 and 15 storage days at 8 degrees C onto Sorbitol MacConkey Agar supplemented with potassium tellurite and cefixime (CT-SMAC). O157:H7 was not present in the pasteurised milk prior to the artificial inoculation. At the end of the processing the cheese had 10 to 100 times more STEC O157: H7 than the initial inoculum. During the storage, the Minas frescal cheese exhibited the largest population increase on the 4th and 5th day when inoculated with 10(2) and 10(3) cells.mL(-1), respectively. Additionally, viable cells were found up to the 10th and 15th day, according to the amount of initial inoculum. This number of cells is able to cause infection in humans, and therefore, Minas frescal cheese, even when stored under refrigeration, is a potential vehicle of disease caused by STEC O157:H7.

The mossy fiber (MF) pathway is critical to hippocampal function and influenced by gonadal hormones. Physiological data are limited, so we asked whether basal transmission and long- term potentiation (LTP) differed in slices of adult male and female rats. The results showed small sex differences in basal transmission but striking sex differences in opioid receptor sensitivity and LTP. When slices were made from females on proestrous morning, when serum levels of 17 beta- estradiol peak, the nonspecific opioid receptor antagonist naloxone (1 mu M) enhanced MF transmission but there was no effect in males, suggesting preferential opioid receptor-dependent inhibition in females when 17 beta-estradiol levels are elevated. The mu-opioid receptor ( MOR) antagonist Cys2,Tyr3,Orn5,Pen7- amide (CTOP; 300 nM) had a similar effect but the delta-opioid receptor (DOR) antagonist naltrindole (NTI; 1 mu M) did not, implicating MORs in female MF transmission. TheGABreceptor antagonist saclofen (200 mu M) occluded effects of CTOP but theGABAA receptor antagonist bicuculline (10 mu M) did not. For LTP, a low-frequency (LF) protocol was used because higher frequencies elicited hyperexcitability in females. Proestrous females exhibited LF-LTP but males did not, suggesting a lower threshold for synaptic plasticity when 17 beta-estradiol is elevated. NTI blocked LF-LTP in proestrous females, but CTOP did not. Electron microscopy revealed more DOR-labeled spines of pyramidal cells in proestrous females than males. Therefore, we suggest that increased postsynaptic DORs mediate LF-LTP in proestrous females. The results show strong MOR regulation of MF transmission only in females and identify a novel DOR-dependent form of MF LTP specific to proestrus.

Abuse and addiction to prescription opioids such as oxycodone (a short-acting Mu opioid receptor (MOP-r) agonist) in adolescence is a pressing public health issue. We have previously shown differences in oxycodone self-administration behaviors between adolescent and adult C57BL/6J mice and expression of striatal neurotransmitter receptor genes, in areas involved in reward. In this study, we aimed to determine whether oxycodone self-administration differentially affects genes regulating synaptic plasticity in the hippocampus of adolescent compared to adult mice, since the hippocampus may be involved in learning aspects associated with chronic drug self administration. Hippocampus was isolated for mRNA analysis from mice that had self administered oxycodone (0.25 mg/kg/infusion) 2 h/day for 14 consecutive days or from yoked saline controls. Gene expression was analyzed with real-time polymerase chain reaction (PCR) using a commercially available "synaptic plasticity'' PCR array containing 84 genes. We found that adolescent and adult control mice significantly differed in the expression of several genes in the absence of oxycodone exposure, including those coding for mitogenactivated protein kinase, calcium/calmodulin-dependent protein kinase II gamma subunit, glutamate receptor, ionotropic AMPA2 and metabotropic 5. Chronic oxycodone self administration increased proviral integration site 1 (Pim1) and thymoma viral proto-oncogene 1 mRNA levels compared to controls in both age groups. Both Pim1 and cadherin 2 mRNAs showed a significant combined effect of Drug Condition and Age x Drug Condition. Furthermore, the mRNA levels of both cadherin 2 and cAMP response element modulators showed an experiment-wise significant difference between oxycodone and saline control in adult but not in adolescent mice. Overall, this study demonstrates for the first time that chronic oxycodone self-administration differentially alters synaptic plasticity gene expression in the hippocampus of adolescent and adult mice. (C) 2014 Published by Elsevier Ltd. on behalf of IBRO.

Arc is a unique immediate early gene whose expression is induced as synapses are being modified during learning. The uniqueness comes from the fact that newly synthesized Arc mRNA is rapidly transported throughout dendrites where it localizes near synapses that were recently activated. Here, we summarize aspects of Arc mRNA translation in dendrites in vivo, focusing especially on features of its expression that are paradoxical or that donot fit in with current models of how Arc protein operates. Findings from in vivo studies that donot quite fit include: (1) Following induction of LIP in vivo, Arc mRNA and protein localize near active synapses, but are also distributed throughout dendrites. In contrast, Arc mRNA localizes selectively near active synapses when stimulation is continued as Arc mRNA is transported into dendrites; (2) Strong induction of Arc expression as a result of a seizure does not lead to a rundown of synaptic efficacy in vivo as would be predicted by the hypothesis that high levels of Arc cause glutamate receptor endocytosis and LTD. (3) Arc protein is synthesized in the perinuclear cytoplasm rapidly after transcriptional activation, indicating that at least a pool of Arc mRNA is not translationally repressed to allow for dendritic delivery; (4) Increases in Arc mRNA in dendrites are not paralleled by increases in levels of exon junction complex (EJC) proteins. These results of studies of mRNA trafficking in neurons in vivo provide a new perspective on the possible roles of Arc in activity-dependent synaptic modifications.

The following is an edited transcript of a recorded discussion session on the topics of "Middle Ear Mechanics" and "Progress in Cochlear Modeling". The discussion, moderated by the authors, took place at the 12th International Workshop on the Mechanics of Hearing held at Cape Sounio, Greece, in June 2014. All participants knew that the session was being recorded. In view of both the spontaneous nature of the discussion and the editing, however, this transcript may not represent the considered or final views of the participants, and may not represent a consensus of experts in the field. The reader is advised to consult additional independent publications.

The barrier to curing HIV-1 is thought to reside primarily in CD4(+) T cells containing silent proviruses. To characterize these latently infected cells, we studied the integration profile of HIV-1 in viremic progressors, individuals receiving antiretroviral therapy, and viremic controllers. Clonally expanded T cells represented the majority of all integrations and increased during therapy. However, none of the 75 expanded T cell clones assayed contained intact virus. In contrast, the cells bearing single integration events decreased in frequency over time on therapy, and the surviving cells were enriched for HIV-1 integration in silent regions of the genome. Finally, there was a strong preference for integration into, or in close proximity to, Alu repeats, which were also enriched in local hotspots for integration. The data indicate that dividing clonally expanded T cells contain defective proviruses and that the replication-competent reservoir is primarily found in CD4(+) T cells that remain relatively quiescent.