Artificial neural networks in cancer research

Current therapy does not cure the majority of patients with B cell non-Hodgkin's lymphoma (NHL) and further intensification does not benefit the patient. Therefore, new approaches are necessary. Immunotherapy has become again a major interest as a new treatment modality for B cell lymphoma since the discovery that the lymphoma specific Id can be presented to antigen-specific T cells. Vaccination of the tumour-bearing host is one of the major strategies to induce a T cell mediated anti-tumour immunity in vivo. For B cell lymphomas the lymphoma specific Id can be used as a tumour-specific antigen to stimulate T cells. Alternatively, the malignant B cells can be modified to become efficient antigen presenting cells (APCs) and present peptides from their own tumour-specific antigens to the autologous T cells. Currently explored and future vaccination strategies for B cell lymphoma will be discussed here.     

Cancer cell necrosis by autoschizis: Synergism of antitumor activity of vitamin C: Vitamin K3 on human bladder carcinoma T24 cells

Scanning and transmission electron microscopy and fluorescence light microscopy were employed to characterize the cytotoxic effects of vitamin C (VitC), vitamin K₃ (VitK₃) or a VitC:VK₃ combination on a human bladder carcinoma cell line (T24) following 1-h and 2-h vitamin treatment. T24 cells exposed to VitC alone exhibited membranous damage (blebs and endoplasmic extrusions, elongated microvilli). VitK₃-treated cells displayed greater membrane damage and enucleation than those treated with VitC as well as cytoplasmic defects characteristic of cytoskeletal damage. VitC:VitK₃-treated cells showed exaggerated membrane damage and an enucleation process in which the perikarya separate from the main cytoplasmic cell body by self-excision. Self-excisions continued for perikarya which contained an intact nucleus surrounded by damaged organelles. After further excisions of cytoplasm, the nuclei exhibited nucleolar segregation and chromatin decondensation followed by nuclear karryorhexis and karyolysis. This process of cell death induced by oxidative stress was named autoschizis because it showed both apoptotic and necrotic morphologic characteristics.     

Theoretical insularity and the crisis of psychoanalysis.

It is argued that the tendency of psychoanalysis toward sectarianism, the inclination to isolate theoretical viewpoints from each other, rather than pluralism, the active engagement of differences, is a significant factor in the loss of influence psychoanalysis has suffered. A brief history is given of the fate of theoretical differences in the field to show the historical sectarianism of psychoanalytic thought. The contention is that the resulting inability of psychoanalysis to define itself, even as a pluralistic discipline, renders it vulnerable to the criticism that the field has little claim to be a branch of knowledge, or to achieve scientific status, even under the most liberal definition of that term. The contention is that the failure to engage differences openly bears a closer kinship to religion than human science. A plea is made for dialogue in the Heideggerean sense of openness to difference so that psychoanalysis can establish itself as a human science characterized by the pluralism of intellectual dialogue rather than the insularity of sectarianism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Information from time-varying vibrotactile stimuli

Experiments have been carried out to investigate the information transfer available via a single vibrator on the fingertip. In a first experiment, for stimuli with durations 80 to 320 ms, discrimination of a one-octave step change in frequency at the halfway point was investigated. Results were similar for three stimulus types--sinewave, monophasic pulse and tetraphasic pulse--suggesting temporal cues are more important than spectral cues in this task. In a second experiment, subjects were required to perceive changes in a sequence of stimulus elements. A presentation rate of 6.25 elements s-1 was found to give better results than a rate of 12.5 elements s-1. In the former case, the potential information transfer per element was estimated to be approximately 1.0 bits, corresponding to an information transfer rate of around 6 bits s-1. Implications for the design of a tactile aid to lipreading are discussed.     

Human Myt1 is a cell cycle-regulated kinase that inhibits Cdc2 but not Cdk2 activity

Activation of the Cdc2.cyclin B kinase is a pivotal step of mitotic initiation. This step is mediated principally by the dephosphorylation of residues threonine 14 (Thr14) and tyrosine 15 (Tyr15) on the Cdc2 catalytic subunit. In several organisms homologs of the Wee1 kinase have been shown to be the major activity responsible for phosphorylating the Tyr15 inhibitory site. A membrane-bound kinase capable of phosphorylating residue Thr14, the Myt1 kinase, has been identified in the frog Xenopus laevis and more recently in human. In this study, we have examined the substrate specificity and cell cycle regulation of the human Myt1 kinase. We find that human Myt1 phosphorylates and inactivates Cdc2-containing cyclin complexes but not complexes containing Cdk2 or Cdk4. Analysis of endogenous Myt1 demonstrates that it remains membrane-bound throughout the cell cycle, but its kinase activity decreased during M phase arrest, when Myt1 became hyperphosphorylated. Further, Cdc2. cyclin B1 was capable of phosphorylating Myt1 in vitro, but this phosphorylation did not affect Myt1 kinase activity. These findings suggest that human Myt1 is negatively regulated by an M phase-activated kinase and that Myt1 inhibits mitosis due to its specificity for Cdc2.cyclin complexes.     

Transmission electron microscopy and scanning force microscopy of poly r(A-U) and poly r(A-U)-ethidium bromide

Transmission electron microscopy and scanning force microscopy of negative-stained, carbon-coated replica and mica-adsorbed preparations of 200 μM poly r(A-U) and 50 μM ethidium bromide/200 μM poly r(A-U) have been employed to evaluate ethidium-induced changes in poly r(A-U) topology. Poly r(A-U) alone exhibits elongated conformations 85–115 nm in length that possess a number of hairpin loops as well as single-stranded domains. While the double-stranded domains are found predominately at the base of the hairpin loops (diameter = 5–30 nm), other rod-like (presumably double-stranded) regions ranging from 25–80 nm in length are present in other portions of the poly r(A-U). In contrast with the poly r(A-U) alone, the EB/poly r(A-U) combination appears as a heterogeneous population of condensed structures whose lengths and widths vary from 12–88 nm and 15–45 nm, respectively. These conformational changes are due to a number of factors, including the displacement of ordered water surrounding the poly r(A-U) and charge shielding of the phosphate groups of the poly r(A-U) upon the binding of the ethidium.     

The variably spaced superlattice energy filter quantum well avalanche photodiode: A solid-state photomultiplier

A new highly-efficient, single-carrier-type avalanche photodiode is presented based on impact ionization across the band edge discontinuity. A resonant tunneling superlattice structure, the variably spaced superlattice energy filter (VSSEF), is used to selectively tune the incident electron distribution to the quantum well impact excitation energy. The gain is greatly enhanced within the structure for two reasons: most of the incident electrons contribute to the ionization process in each stage of the device, and the lowest lying subbands, which are by far the most highly occupied, can be ionized. It is predicted that multiple ionization, similar to secondary emission in photomultiplier tubes, can occur thereby greatly enhancing the gain of the device. The device behaves in principle more like a photomultiplier than other existing solid-state photodetectors since more than one secondary carrier can be produced per initiating carrier per stage of the device. Representative devices are presented for the Ga0.47In0.53As/ (Al0.48In0.52AsBa0.17Sr0.83F2) and GaAs/(AlGaAs-ZnSe) material systems based on a calculation using first an uncoupled quantum well system and second, a complete resonant tunneling coupled quantum well calculation based on an Airy function approach.     

Computational prediction of PVC degradation during injection molding in a rectangular channel

A computational model has been developed to calculate the degradation of PVC during injection molding. The results in this work are for the flow in a rectangular geometry. The effects of the injection speed, melt temperature, and material properties were examined. It was determined that the principal factor influencing PVC degradation is the injection speed. Very good agreement between computational and experimental results was obtained. Furthermore, it was calculated that the materials are more thermally sensitive during processing, with activation energy of 65 kcal/mol. Finally, it was calculated that the degradation becomes significant when the melt temperature is above 250°C, independent of the material studied. The model could be used to design the process to avoid degradation. Polym. Eng. Sci. 44:1295–1312, 2004. © 2004 Society of Plastics Engineers.