Brain metabolic activity associated with long-term memory consolidation

The use of day-old chickens trained on a single-trial passive avoidance task provides a useful paradigm for investigations into cellular mechanisms underlying memory formation. Pharmacological intervention studies indicate that there are three temporally identifiable stages of memory processing leading to the consolidation of information for this task. These stages, designated as short-term (STM; up to 15 min), intermediate-term (ITM; 15-55 min), and long-term (LTM; more than 55 min) memory, have been found to be sequentially dependent (Ng and Gibbs, 1989). In addition, ITM appears to consist of two physiologically distinguishable phases, A and B. Evidence in this laboratory suggests that the crossover between these ITM phases (at 30 min after training) represents a critical time-point for the triggering of LTM.     

Defective Expression of β1-Integrins in Cells with Constitutively Active αLβ2-Integrins

We have investigated a potential relationship between expression of β1-integrins and adhesiveness of the β2-integrin LFA-1 (αLβ2, CD11a/CD18). By an approach of random mutagenesis and selection we established clones from the human acute lymphatic leukemia cell line HPB-ALL with (i) constitutively active LFA-1 and (ii) with no apparent integrin-β1 cell surface expression. Thirty-seven of 42 clones selected for activated LFA-1 were found to have lost apparent integrin-β1 expression. Conversely, 7 of 21 clones selected for lack of β1 expression were found to have activated LFA-1. Since this pointed toward a possible coupling between β1 expression and LFA-1 activity, we further analyzed at which level β1 expression was blocked. We focused on one clone, HAP4, with activated LFA-1 and no detectable β1 cell surface expression and found, surprisingly, that it expressed wild-type levels of β1 mRNA and, in Western blots of whole cell lysates, apparently normal levels of β1 protein. However, in addition to β1 of the expected molecular weight, HAP4 expressed a unique 48-kDa band recognized by the polyclonal anti-β1 antiserum. Immunoprecipitation experiments revealed that the epitope recognized by the anti-β1 antibody 4B4 was hidden or lost. The α4-chain was found in its precursor form but it did not associate with any β-chain, and it was not processed to its mature form. Instead α4-chains were eventually degraded. Taken together this showed that β1-chains were produced but not properly processed in HAP4. From this we propose that HAP4 is deficient in a gene product required both for proper β1 folding and for repression of LFA-1 adhesiveness.     

Molecular Comparison of Bacterial Communities on Peripheral Intravenous Catheters and Matched Skin Swabs

Skin bacteria at peripheral intravenous catheter (PIVC) insertion sites pose a serious risk of microbial migration and subsequent colonisation of PIVCs, and the development of catheter related bloodstream infections (CRBSIs). Common skin bacteria are often associated with CRBSIs, therefore the bacterial communities at PIVC skin sites are likely to have major implications for PIVC colonisation. This study aimed to determine the bacterial community structures on skin at PIVC insertion sites and to compare the diversity with associated PIVCs. A total of 10 PIVC skin site swabs and matching PIVC tips were collected by a research nurse from 10 hospitalised medical/surgical patients at catheter removal. All swabs and PIVCs underwent traditional culture and high-throughput sequencing. The bacterial communities on PIVC skin swabs and matching PIVCs were diverse and significantly associated (correlation coefficient = 0.7, p<0.001). Methylobacterium spp. was the dominant genus in all PIVC tip samples, but not so for skin swabs. Sixty-one percent of all reads from the PIVC tips and 36% of all reads from the skin swabs belonged to this genus. Staphylococcus spp., (26%), Pseudomonas spp., (10%) and Acinetobacter spp. (10%) were detected from skin swabs but not from PIVC tips. Most skin associated bacteria commonly associated with CRBSIs were observed on skin sites, but not on PIVCs. Diverse bacterial communities were observed at skin sites despite skin decolonization at PIVC insertion. The positive association of skin and PIVC tip communities provides further evidence that skin is a major source of PIVC colonisation via bacterial migration but microbes present may be different to those traditionally identified via culture methods. The results provide new insights into the colonisation of catheters and potential pathogenesis of bacteria associated with CRBSI, and may assist in developing new strategies designed to reduce the risk of CRBSI.     

Peroxidation of Phospholipids Promoted by Myeloperoxidase

Myeloperoxidase was found to promote peroxidation of phospholipids under acidic conditions in the presence of hydrogen peroxide and iodide ions The peroxidation was markedly enhanced by pyrophosphate-chelated ferric iron and was inhbited by desferrioxamine and superoxide dismutase. This observation adds lipid peroxidation to the oxidative damage caused by myeloperoxidase, which is a phagocytic cell enzyme involved in phapocyte-mediated cell destruction.     

Binding of pp170 to microtubules is regulated by phosphorylation.

We have used a monoclonal antibody affinity column to purify from HeLa cells a protein of molecular weight 170,000 (designated pp170) which we previously identified as a nucleotide-sensitive microtubule-binding protein (Rickard, J. E., and Kreis, T. E. (1990) J. Cell Biol. 110, 1623-1633). We show here that the affinity-purified pp170 binds directly to taxol-polymerized tubulin. This association is not affected directly by MgATP. Addition of MgATP can, however, inhibit binding of pp170 to microtubules in the presence of microtubule-binding proteins from HeLa cells. This effect of MgATP correlates with phosphorylation of pp170 by a microtubule-associated kinase. Potato acid phosphatase dephosphorylates the pp170 and restores the ability of pp170 to bind to microtubules. Furthermore, binding of pp170 to microtubules in a high speed supernatant extract is inhibited by the phosphatase inhibitor okadaic acid, consistent with an inhibitory effect of pp170 phosphorylation on microtubule binding. In vivo, pp170 is phosphorylated on serine residues, with a half-life for the phosphate groups of approximately 2 h. Depolymerization of microtubules with nocodazole abolishes incorporation of 32P into the protein, apparently by increasing the rate of its dephosphorylation. Stabilization of microtubules with taxol reduces the rate of 32P incorporation into pp170 by approximately 50%, but has no significant effect on phosphate loss. These data establish that pp170 is a microtubule-binding protein, and that the microtubule interaction is inhibited by phosphorylation of pp170. The sensitivity of the in vivo phosphorylation state of pp170 to microtubule-active drugs suggests that this posttranslational modification may be an important regulator of the interaction of pp170 with microtubules in cells.     

Genome Sequence of Staphylococcus epidermidis Strain AU12-03, Isolated from an Intravascular Catheter

In recent years, Staphylococcus epidermidis has become a major nosocomial pathogen and the most common cause of intravascular catheter-related bacteremia, which can increase morbidity and mortality and significantly affect patient recovery. We report a draft genome sequence of Staphylococcus epidermidis AU12-03, isolated from an intravascular catheter tip.     

Phosphatidylinositol Phosphate 5-Kinase Iγi2 in Association with Src Controls Anchorage-independent Growth of Tumor Cells

A fundamental property of tumor cells is to defy anoikis, cell death caused by a lack of cell-matrix interaction, and grow in an anchorage-independent manner. How tumor cells organize signaling molecules at the plasma membrane to sustain oncogenic signals in the absence of cell-matrix interactions remains poorly understood. Here, we describe a role for phosphatidylinositol 4-phosphate 5-kinase (PIPK) Iγi2 in controlling anchorage-independent growth of tumor cells in coordination with the proto-oncogene Src. PIPKIγi2 regulated Src activation downstream of growth factor receptors and integrins. PIPKIγi2 directly interacted with the C-terminal tail of Src and regulated its subcellular localization in concert with talin, a cytoskeletal protein targeted to focal adhesions. Co-expression of PIPKIγi2 and Src synergistically induced the anchorage-independent growth of nonmalignant cells. This study uncovers a novel mechanism where a phosphoinositide-synthesizing enzyme, PIPKIγi2, functions with the proto-oncogene Src, to regulate oncogenic signaling.     

Biphalangia of the lateral toes. A study on the incidence in a Swedish population together with some observations on digital sesamoid bones in the foot

The incidence of a two-phalangeal fifth toe in a Swedish population has been investigated in a series of 496 persons. The incidence is about 35% without significant differences between sexes or between age groups. The figure coincides with that found in studies on German, English and Danish populations but differs from that of American and that of Japanese populations. It is concluded that the cause of this anomaly is genetic and that the two-phalangeal fifth toe may be an important parameter in racial studies and for the identification of an individual. Each phalanx in the two-phalangeal toe is on the average almost 5 mm longer than its counterpart in the three-phalangeal variety, resulting in the paradoxic fact that the three-phalangeal toe is shorter on the average than the two-phalangeal one. The numbers of sesamoid bones in various locations of the toes are presented.     

A comparison of in vitro and in vivo estimates of the viability of Taenia pisiformis eggs aged under controlled conditions, and their ability to immunise against a challenge infection

Storing the eggs of T. pisiformis for periods of 0 to 9 days at a temperature of 36–38°C and relative humidity of 87–93 % revealed at least 4 stages in the ageing process. Firstly, a stage in which eggs hatched and activated in vitro and were also fully infective for rabbits. Secondly, a stage in which eggs hatched and activated in vitro but underwent only partial development in rabbits. Thirdly, a stage in which eggs hatched and activated in vitro, and presumably therefore in vivo, but no evidence of infection could be found when they were fed to rabbits. Fourthly, a stage in which eggs either did not hatch, or if they did hatch, the oncosphere was rapidly digested. In vitro techniques for assessing viability of T. pisiformis eggs were not a reliable guide to their infectivity for rabbits. ‘Senescent’ eggs, that is eggs which produced evidence of early infection in rabbits but did not complete their development to cysticerci, failed to produce immunity to challenge infection with T. pisiformis eggs.