Valence-bond crystal in a pyrochlore antiferromagnet with orbital degeneracy.

We discuss the ground state of a pyrochlore lattice of threefold orbitally degenerate S=1/2 magnetic ions. We derive an effective spin-orbital Hamiltonian and show that the orbital degrees of freedom can modulate the spin exchange, removing the infinite spin-degeneracy characteristic of pyrochlore structures. The resulting state is a collection of spin-singlet dimers, with a residual degeneracy due to their relative orientation.

The p68 and p72 DEAD box RNA helicases interact with HDAC1 and repress transcription in a promoter-specific manner.

Background: p68 (Ddx5) and p72 (Ddx17) are highly related members of the DEAD box family and are established RNA helicases. They have been implicated in growth regulation and have been shown to be involved in both pre-mRNA and pre-rRNA processing. More recently, however, these proteins have been reported to act as transcriptional co-activators for estrogen-receptor alpha (ER alpha).

Induction of transcription by p21Waf1/Cip1/Sdi1: role of NFkappaB and effect of non-steroidal anti-inflammatory drugs.

p21(Waf1/Cip1/Sdi1) is the primary mediator of cell cycle arrest in response to different forms of stress and in the programs of senescence and differentiation. p21 interacts with many regulatory proteins and has broad effects on cellular gene expression. p21 was previously shown to stimulate NFkappaB transcriptional activity through its effect on the p300/CBP transcription cofactor family.

Reprogramming RelA.

The diversity of activators and targets of the NF-kappaB transcription factor family demands that there be regulatory mechanisms in place to control the specificity with which genes under their control are induced. In part this can be achieved through selective induction of different NF-kappaB subunits and through co-operative interactions with heterologous DNA-binding proteins and co-activators. Recent work from our laboratory indicates another critical mechanism regulating NF-kappaB.

Sheep-farm risk factors for ivermectin resistance in Ostertagia circumcincta in Western Australia.

On-farm risk factors associated with ivermectin resistance on sheep farms in Western Australia were identified from data derived from a postal survey of 235 farmers who had conducted a fecal egg-count-reduction test in 1999, 2000, or both years. A response of 54% was achieved. We developed a logistic-regression model.

NF-kappaB: tumor promoter or suppressor?

A role for the NF-kappaB family of transcription factors as tumor promoters is firmly established. However, other data suggest that NF-kappaB can also inhibit tumor growth. Moreover, NF-kappaB activity is modulated by tumor suppressors, such as p53 and ARF, whereby NF-kappaB subunits repress, rather than activate, the expression of tumor-promoting genes.

Active repression of antiapoptotic gene expression by RelA(p65) NF-kappa B.

With the emerging role of NF-kappa B in cancer it is important that its responses to stimuli relevant to tumor progression and therapy are understood. Here, we demonstrate that NF-kappa B induced by cytotoxic stimuli, such as ultraviolet light (UV-C) and the chemotherapeutic drugs daunorubicin/doxorubicin, is functionally distinct to that seen with the inflammatory cytokine TNF and is an active repressor of antiapoptotic gene expression. Surprisingly, these effects are mediated by the RelA(p65) NF-kappa B subunit.

Free available chlorine in commercial broiler chicken drinking water in New Zealand.

Free available chlorine (FAC) concentrations in drinking water supplied to broiler chickens grown commercially in New Zealand were monitored for 11 farms in two companies. Different sites within a growout house were examined at different times of the day to determine spatial and temporal differences in FAC concentrations. Taps provided water with significantly higher FAC concentrations than did drinkers.

Oncogenes, tumor suppressors and p52 NF-kappaB.

A role for the p52 NF-kappaB subunit in tumorigenesis has been steadily emerging since its discovery as a gene associated with chromosomal translocations in B- and T-cell lymphomas. Now Eliopoulos and co-workers have extended these studies to examine the effect of the Epstein-Barr virus (EBV)-encoded latent infection membrane protein 1 (LMP1) on p52. They find that LMP1 stimulates the processing of p100 to p52 NF-kappaB.

The impact of a monthly rest day on avian influenza virus isolation rates in retail live poultry markets in Hong Kong.

Retail live poultry markets (LPMs) may act as a reservoir of avian influenza viruses (AIV). In this study we test the hypothesis that a rest day in the LPMs where the stalls are completely emptied of poultry, cleansed, and restocked will reduce the isolation rates of avian influenza viruses. The isolation rate of H9N2 subtype viruses from chicken was significantly lower after the rest day than prior to it, indicating its impact in reducing transmission.

Inflammation and hyperalgesia induced by nerve injury in the rat: a key role of mast cells.

Inflammatory cells and their mediators are known to contribute to neuropathic pain following nerve injury. Mast cells play a key role in non-neural models of inflammation and we propose that mast cells and their mediators (in particular histamine) are important in the development of neuropathic pain. In rats, where the sciatic nerve was partially ligated, we showed that stabilisation of mast cells with sodium cromoglycate reduced the recruitment of neutrophils and monocytes to the injured nerve and suppressed the development of hyperalgesia.

The p53-inhibitor pifithrin-alpha inhibits firefly luciferase activity in vivo and in vitro.

Background: Pifithrin-alpha is a small molecule inhibitor of p53 transcriptional activity. It has been proposed that the use of pifithrin-alpha in conjunction with chemotherapeutic and radiation therapies for cancer will reduce the side effects of these treatments in normal tissue that still contains wild type p53. In addition, pifithrin-alpha provides a useful tool in the laboratory to investigate the function of p53 in model systems.

p53- and Mdm2-independent repression of NF-kappa B transactivation by the ARF tumor suppressor.

One mechanism by which a cell affords protection from the transforming effects of oncogenes is via the action of the tumor suppressor, ARF, which activates p53 by inactivating Mdm2. Many oncogenes have also been shown to activate the transcription factor NF-kappa B, which can contribute toward the malignant phenotype in many ways, including an ability to antagonize p53. Here we find that ARF inhibits NF-kappa B function and its antiapoptotic activity independent of Mdm2 and p53.

p53 represses cyclin D1 transcription through down regulation of Bcl-3 and inducing increased association of the p52 NF-kappaB subunit with histone deacetylase 1.

The p53 and NF-kappaB transcription factor families are important, multifunctional regulators of the cellular response to stress. Here we have investigated the regulatory mechanisms controlling p53-dependent cell cycle arrest and cross talk with NF-kappaB. Upon induction of p53 in H1299 or U-2 OS cells, we observed specific repression of cyclin D1 promoter activity, correlating with a decrease in cyclin D1 protein and mRNA levels.

A novel regional citrate anticoagulation protocol for CRRT using only commercially available solutions.

Purpose: To describe a citrate regional anticoagulation (CRA) protocol for patients with acute renal failure and contraindications to heparin who require continuous renal replacement therapy (CRRT), using only commercially available solutions, for units that do not want or cannot prepare extemporaneously made solutions.

Materials And Methods: Case report and series from a medical/surgical intensive care unit of a university teaching hospital. A CRA protocol was developed by using only commercially available solutions.

P300 transcriptional repression is mediated by SUMO modification.

p300 and CREB binding protein can both activate and repress transcription. Here, we locate the CRD1 transcriptional repression domain between residues 1017 and 1029 of p300. This region contains two copies of the sequence psiKxE that are modified by the ubiquitin-like protein SUMO-1.

Regulation of RelA (p65) function by the large subunit of replication factor C.

The RelA (p65) subunit of NF-kappaB is an important regulator of inflammation, proliferation, and apoptosis. We have discovered that the large subunit, p140, of replication factor C (RFC) can function as a regulator of RelA. RFC is a clamp loader, facilitating the addition and removal of proliferating-cell nuclear antigen from DNA during replication and repair but can also interact directly with the retinoblastoma tumor suppressor protein and the transcription factor C/EBPalpha.

DNA-dependent acetylation of p53 by the transcription coactivator p300.

Reconstitution of the stages in the assembly of the p300.p53 transcription complex has identified a novel type of DNA-dependent regulation of p300-catalyzed acetylation. Phosphorylation at the CHK2 site (Ser(20)) in the N-terminal activation domain of p53 stabilized p300 binding.

Induction of transcription through the p300 CRD1 motif by p21WAF1/CIP1 is core promoter specific and cyclin dependent kinase independent.

The tumor suppressors p300 and CREB-binding protein (CBP) are both multifunctional transcriptional coactivators. We have previously found that the cyclin dependent kinase (CDK) inhibitor p21(WAF1/CIP1) can stimulate transactivation by p300 and CBP through inhibiting transcriptional repression by a discrete domain within these proteins termed CRD1. Given the large number of p300/CBP associated functions, it is unlikely that p21 regulates the expression of every gene under their control, however.

Effectiveness of an antagonist to gonadotrophin releasing hormone on the FSH and LH response to GnRH in perifused equine pituitary cells, and in seasonally acyclic mares.

We wish to use a gonadotrophin-releasing hormone (GnRH) antagonist in the mare as a tool for investigating the control of the oestrous cycle. The aim of this study was to test the effectiveness of the antagonist cetrorelix by testing both in vitro, using perifused equine anterior pituitary cells, and in vivo in seasonally acyclic mares. Pituitary cells were prepared and after 3-4 days incubation, loaded onto columns and given four pulses of GnRH (at 0, 30, 60 and 90 min; dose-response study).

The ETS domain transcription factor Elk-1 contains a novel class of repression domain.

The ETS domain transcription factor Elk-1 serves as an integration point for different mitogen-activated protein (MAP) kinase pathways. Phosphorylation of Elk-1 by MAP kinases triggers its activation. However, while the activation process is well understood, its downregulation-inactivation is less well characterized.

Learning to use minimal access surgical instruments and 2-dimensional remote visual feedback: how difficult is the task for novices?

Performing minimal access surgery requires the use of 2-dimensional information to produce 3-dimensional movements, as well as precise motor control for manipulating laparoscopic tools. The added visuomotor demands of this task make it more demanding and complex than traditional open surgery. The purpose of this study was to determine the relative task difficulty of performing laparoscopic tool movements with normal vision or 'laparoscopic vision' provided by a remote 2-D monitor.