Target selection difficulty, negative priming, and aging.

It has been recently suggested that the presence of identity negative priming effects in old adults could occur when there is substantial processing of the distracting information in a selective attention task (J. M. Kieley & A. A. Hartley, 1997). In three experiments, using a letter identification task, it was found that making target selection more difficult increased the magnitude of the negative priming effect to a similar extent in both young and old adults. Moreover, the size of the negative priming effect did not differ between young and elderly participants. These results are discussed with respect to the issue of age-related deficits in the mechanisms underlying negative priming. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Oxide Thin Films for Tunable Microwave Devices

Oxide thin films have been studied for frequency and phase agile electronics. The electric-field tuning of microwave devices employs ferroelectrics, while the Magnetic-field tuning uses ferrites. The critical material parameters for ferroelectric thin films are the tunability of the dielectric constant and the dielectric loss. This paper describes the current understanding of the fundamental mechanisms of these properties and the research efforts to improve them in ferroelectric thin films.     

Purification and characterization of two extracellular proteinases from Arthrobacter nicotianae 9458

A community effect was found to occur between heterogeneous tumor cell populations leading to an overall increased tumorigenicity without a clonal dominance of the more tumorigenic clone. In the rat bladder carcinoma cell line NBT-II, this effect appears mediated by the Fibroblast Growth Factor-1 (FGF-1) through either a direct or an indirect signaling pathway. Neovascularization induced by FGF-1 was found not to be responsible for the community effect. The present study shows that the community effect does not involve a direct FGF-1 signaling since tumor cells expressing a dominant-negative FGF receptor mutant were still responding to the highly tumorigenic FGF-1 expressing cells. Tumors arising from inoculates of the FGF-1 producing NBT-II cells mixed with non tumorigenic epithelial MDCK cells contain only the tumorigenic cells indicating that MDCK cells may exerce a helper effect for the growth of the tumor not dependant on their own growth. Therefore the helper function of MDCK cells must be distinguished from a community effect where the contribution of low tumorigenic cells not only provides an in vivo growth advantage to few highly tumorigenic cells but become themselves highly tumorigenic indicating that the community effect may require cell-cell specific cooperativity independent from an helper effect.     

Distraction osteogenesis of the mandible using a submerged intraoral device: a report of three cases

OBJECTIVE: To compare the value of current transthoracic echocardiographic systems and transoesophageal echocardiography for assessing left atrial appendage function and imaging thrombi. DESIGN: Single blind prospective study. Patients were first investigated by transthoracic echocardiography and thereafter by a second investigator using transoesophageal echocardiography. The feasibility of imaging the left atrial appendage, recording its velocities, and identifying thrombi within the appendage were determined by both methods. PATIENTS: 117 consecutive patients with a stroke or transient neurological deficit. SETTING: Tertiary cardiac and neurological care centre. RESULTS: Imaging of the complete appendage was feasible in 75% of the patients by transthoracic echocardiography and in 95% by transoesophageal echocardiography. Both methods were concordant for the detection of thrombi in 10 cases. Transoesophageal echocardiography revealed two additional thrombi. In one of these patients, transthoracic echocardiography was not feasible and in the other the thrombus had been missed by transthoracic examination. In patients with adequate transthoracic echogenicity, the specificity and sensitivity of detecting left atrial appendage thrombi were 100% and 91%, respectively. Recording of left atrial appendage velocities by transthoracic echocardiography was feasible in 69% of cases. None of the patients with a velocity > 0.3 m/s had left atrial appendage thrombi. In the one patient in whom transthoracic echocardiographic evaluation missed a left atrial appendage thrombus, the peak emptying velocity of the left atrial appendage was 0.25 m/s. CONCLUSIONS: A new generation echocardiographic system allows for the transthoracic detection of left atrial appendage thrombi and accurate determination of left atrial appendage function in most patients with a neurological deficit.     

Electrospray quadrupole mass spectrometry analysis of model oligonucleotides and polymerase chain reaction products: determination of base substitutions, nucleotide additions/deletions, and chemical modifications.

ESI FTICR mass spectrometry is the only technique currently used for accurate molecular weight analysis of PCR products above 100 bp in size. This is important in demonstrating the potential for MS in making major contributions in the molecular biology and genomics areas. In the near future, it is more likely that less expensive, more user friendly MS techniques will be used for high-throughput analyses (including MALDI TOF and ESI quadrupole). There have been numerous reports on the use of MALDI TOF. The current report is to the first to evaluate the use of ESI-quadrupole analysis of PCR products. Synthetic oligonucleotides (30 and 89 mers) and polymerase chain reaction products of varying molecular weight (62, 88, 89, and 114 bp) were analyzed by ESI using a quadrupole MS. The mass accuracy for nucleic acids in the 30-62 bp range was shown to allow determination of nucleotide substitutions and additions/deletions. For higher molecular weight PCR products (88-114 bp), the mass accuracy of ESI-MS distinguishes single or multiple nucleotide insertions/deletions. In addition, ESI quadrupole MS allows determination of molecular weight of both strands of higher molecular weight ds PCR products and can distinguish nucleotide modifications (e.g., with biotin). In conclusion, it is demonstrated that ESI-MS occupies an intermediate position (as compared to MALDI TOF and ESI FTICR) with regard to mass accuracy and resolution in analysis of nucleic acids.     

Breast cancer angiogenesis--new approaches to therapy via antiangiogenesis, hypoxic activated drugs, and vascular targeting

Several groups have shown that quantitation of tumor angiogenesis by counting blood vessels in primary breast cancer gives an independent assessment of prognosis. Poor prognosis is associated with high blood vessel counts. We have shown that the rate of cell division in endothelial cells is much higher in breast tumours than in normal breast. Breast cancer cell lines and primary human breast tumours express a wide range of vascular growth factors, including VEGF, placenta growth factor, pleiotrophin, TGF beta 1, acidic and basic FGF, and platelet-derived endothelial cell growth factor. Inhibiting angiogenesis by blocking vascular growth factors would be difficult with highly specific agents, but drugs with a broader spectrum of antagonism may be effective. We have developed several suramin analogues which are less toxic than suramin in vivo but more potent in inhibiting angiogenesis, and these have been developed for Phase I. A combination of anti-angiogenesis agents with drugs activated by hypoxia may also be useful, because anti-angiogenesis alone may not kill cells, whereas activation of hypoxic drugs could synergize. New endpoints may be necessary because inhibition of new blood vessel formation may not cause tumour regression. Thus, the endpoint of stable disease and biochemical assessment of inhibition of angiogenesis may be much more important in therapeutic studies and for drug development in the future. The prognostic importance of angiogenesis suggests that this should be a major new therapeutic target.     

Microglia-passaged simian immunodeficiency virus induces neurophysiological abnormalities in monkeys

Four rhesus macaques were inoculated intravenously with a cryopreserved stock of microglia obtained from a simian immunodeficiency virus (SIV)-infected rhesus macaque. Before infection, three of the four monkeys were trained and tested daily on a computerized neuropsychological test battery. After SIV infection, behavioral testing continued to monitor deficits associated with disease progression. Five additional age-matched, behaviorally trained monkeys served as controls. Neurophysiological testing for visual and auditory evoked responses was accomplished 37-52 weeks after infection in all monkeys. Subsequently, all four SIV-infected monkeys and one control subject were sacrificed, and samples of brain tissue were taken for pathological analysis. SIV-infected monkeys demonstrated abnormal responses in both auditory and visual evoked responses. In addition, around the time of electrophysiological recording, all three SIV-infected, behaviorally trained monkeys exhibited significant decreases in progressive-ratio performance, reflecting a reduction in reinforcer efficacy. One subject also demonstrated impairments in shifting of attentional set and motor ability at that time. Neuropathological evaluation revealed that all four SIV-infected monkeys exhibited numerous perivascular and parenchymal infiltrating T cells. These findings document that SIV causes electrophysiological, behavioral, and neuropathological sequelae similar to what has been observed in the human neuroAIDS syndrome. Our observations further validate the simian model for the investigation of the pathogenesis of AIDS dementia and for the investigation of drugs with potential therapeutic benefits.     

Exact solutions of cyclically symmetric oscillator equations with non-linear coupling

Kaplan and Yardeni have found very simple exact limit cycle solutions in cyclically symmetric systems of N oscillator equations with linear coupling in zero order of a perturbation parameter and non-linear coupling in first order. In contrast with such solutions in other non-linear systems, each of these limit cycles is a normal mode of the unperturbed equations, with no change in frequency. the sources of this simple behaviour are studied here with the equations expressed in terms of the normal mode co-ordinates of the unperturbed system rather than in the original co-ordinates. It is found that the simplicity of the Kaplan-Yardeni solutions arises partly from an additional symmetry of the perturbation terms beyond the cyclic symmetry and partly from the specific choices of the perturbations. Extension of their systems to arbitrary N leads to the result that all such sets of equations have similar simple limit cycles. More general cyclically symmetric sets of equations are also discussed, with limit cycle solutions whose frequencies are shifted from the zero-order values by easily calculated amounts or with solutions which are linear combinations of zero-order normal modes.     

Allocating data to distributed-memory multiprocessors by genetic algorithms

We present three genetic algorithms (GAs) for allocating irregular data sets to multiprocessors. These are a sequential hybrid GA, a coarse-grain GA and a fine-grain GA. The last two are based on models of natural evolution that are suitable for parallel implementation; they have been implemented on a hypercube and a Connection Machine. Experimental results show that the three GAs evolve good suboptimal solutions which are better than those produced by other methods. The GAs are also robust and do not show a bias towards particular problem configurations. The two parallel GAs have reasonable execution times, with the coarse-grain GA producing better solutions for the allocation of loosely synchronous computations.