Epidermal growth factor enhancement of skin tumor induction in mice

Summary Subcutaneous injection of epidermal growth factor 1. significantly shortened the latency period for the appearance of methylcholanthrene induced skin tumors and 2. increased the average number of papillomas elicited per mouse in both the Swiss Webster and C3HeB/FeJ strains.Acknowledgments. This research was supported by USPHS NCI Grant No. CA 15276 and Contract No. GEN-12 between the Regents of the University of California and the U.S. Energy Research and Development Administration. We thankIlmar Lepik for his assistance in some phases of these experiments.     

Silent spread of H5N1 in vaccinated poultry

International debate on the merits of vaccinating poultry against the H5N1 influenza A virus has raised concerns about the possibility of an increased risk of between-flock transmission before outbreaks are detected. Here we show that this 'silent spread' can occur because of incomplete protection at the flock level, even if a vaccine is effective in individual birds. The use of unvaccinated sentinels can mitigate, although not completely eliminate, the problem.     

The First-, Second- and Third-Person Dynamics of Learning History

Learning history is a well delineated action research process consisting of consecutive stages of inquiry where groups and individuals engage in learning and reflecting on their past shared, but often multiple, experiences as these are recorded in a ‘learning history’. Learning history has much in common with other forms of action research in that it configures first-, second- and third-person processes of inquiry in a particular way and enacts research qualities of rigour, relevance and reflexivity. Yet these and other links have as yet been tacit and under articulated - resulting in learning history often conceived as a distinctive linear method with the practice of learning history likewise confined. This reflective article opens out and makes explicit the inherent first- second- and third- person dynamics of learning history. These dynamics are explored from the point of view of different actors – the historian, the participant and the reader - in a learning history process and connections to a general empirical method are made. Finally questions of quality in a learning history are discussed. The aim of this article is to establish firmer methodological foundations for the learning history approach and to provide practical insight into how action researchers might engage more readily in learning history work.     

Biologically diverse molecular variants within a single HIV-1 isolate

AIDS is a disorder characterized by a slow progressive impairment of immune function and by infection of human immunodeficiency viruses (HIV-1, HIV-2). Our knowledge of how these viruses cause disease in man, or how the related lentiviruses (visna and equine infectious anaemia virus) cause disease in animals, is still fragmentary. In particular, the significance of genetic variation in HIV-1, occurring within populations, within individuals and over periods of time, and the mechanisms of viral persistence remain unclear. To address these issues we prepared a series of proviral clones of HIV-1 originating from a single patient and compared their biological properties. Here we show that hybrid genomes (in which the envelope region of six viral clones were separately substituted into a prototype HIV-1 genome) generated viruses with widely differing capacity to grow in human T cells, cell lines and monocytoid cultures. These data suggest that extensive biological variation exists in vivo within an infected individual and is in part determined at the level of the viral envelope.     

Review of Aeromonas enterotoxins

This report reviews the work of other investigators regarding Aeromonas toxins and describes work conducted in our laboratory relating to the biochemical characterization of a cytolytic factor with an antigenic moiety that cross-reacts with cholera toxin (referred to as CTC-cytolysin), as well as the purification and partial characterization of a non-CTC enterotoxin. These two toxins were produced by Aeromonas hydrophila, isolate SSU, and are capable of causing fluid accumulation in animal models.     

An integrated nanocarbon–cellulose membrane for solid-state supercapacitors

In this work, we demonstrate the assembly of oxidised carbon nanohybrids(o CNHs) with a commercial cellulose membrane for solid-state supercapacitors. The o CNHs–cellulose membranes were prepared by filtering a water dispersion of o CNHs through the cellulose membrane. The o CNHs were derived from carbon nanotubes via a modified Hummer’s method and contained both closed tubes and unzipped tubes, which indicated a hybrid geometrical structure. The solid-state supercapacitor based on the o CNHs–cellulose membranes showed a high areal capacitance of *75 m F/cm~2 at a low scan rate(5 m V/s)and excellent stability for 1,000 cycles.     

Microring-Assisted Coupling Between Dissimilar Waveguides

The use of microring resonators to assist in the evanescent field coupling between dissimilar waveguides is proposed and analyzed. Theoretical analysis based on the coupled mode theory and nu-merical example show that complete cross power transfers can be obtained near the microring resonances. Applications of the device include power dividers, low-power thermo-optic or electro-optic switches, and modulators.     

Binding of paxillin to alpha4 integrins modifies integrin-dependent biological responses

The alpha4 integrins are indispensable for embryogenesis, haematopoiesis and immune responses, possibly because alpha4 regulates cellular functions differently from other integrins through its cytoplasmic tail. We used novel mimics of the alpha4 tail to identify molecules that could account for alpha4-specific signalling. Here we report that the alpha4 tail, but not several other alpha-subunit tails, binds tightly to the signalling adaptor paxillin. Paxillin physically associated with alpha4 integrins in Jurkat T cells at high stoichiometry, and joining the alpha4 tail to alphaIIb resulted in a complex of integrin alphaIIbbeta3 with paxillin. This association markedly enhanced the rates of alphaIIbbeta3-dependent phosphorylation of focal adhesion kinase and cell migration. It also reduced cell spreading, focal adhesion and stress fibre formation. A point mutation within the alpha4 tail that disrupts paxillin binding reversed all of these effects. Furthermore, alpha4beta1-dependent adhesion to VCAM-1 led to spreading of mouse embryonic fibroblasts derived from paxillin-null but not from wild-type mice. Thus, the tight association of paxillin with the alpha4 tail leads to distinct biochemical and biological responses to integrin-mediated cell adhesion.