Report from a workshop on multianalyte microsphere assays

Multiplexed assays using fluorescent microspheres is an exciting technique that has been gaining popularity among researchers, particularly those in the public health field. Part of its popularity is due to its flexibility, as both immunoassays and oligonucleotide hybridization assays can be developed on this platform. This report summarizes a workshop held by the Centers for Disease Control and Prevention that discussed issues surrounding these assays and the Luminex 100 xMAP instrument. Topics included instrumentation, assay design, sample matrix and volume, quality control, and development of commercial applications.     

The second Conceptual Assessment in the Biological Sciences workshop

A second National Science Foundation-sponsored workshop on Conceptual Assessment in Biology was held in January 2008. Reports prepared for the workshop revealed that research groups working in a variety of biological sciences are continuing to develop conceptual assessment instruments for use in the classroom. Discussions at this meeting largely focused on two issues: 1) the utility of the backwards design approach of Wiggins and McTighe (11), in which identification of learning outcomes (determining what to assess) lies at the beginning of course design; and 2) the utility of defining expected learning outcomes as the building of runable mental models (and designing conceptual assessments that would test the correctness of these mental models). A third meeting is being planned that will focus on the processes involved in writing and validating conceptual assessment instruments.     

Zinc homeostasis and immunosenescence

For more than 50 years, zinc is known to be an essential trace element, having a regulatory role in the immune system. Deficiency in zinc thus compromises proper immune function, like it is observed in the elderly population. Here mild zinc deficiency is a common condition, documented by a decline of serum or plasma zinc levels with age. This leads to a dysregulation mainly in the adaptive immunity that can result in an increased production of pro-inflammatory cytokines, known as a status called inflamm-aging. T cell activation as well as polarization of T helper (Th) cells into their different subpopulations (Th1, Th2, Th17, regulatory T cells (Treg)) is highly influenced by zinc homeostasis. In the elderly a shift of the Th cell balance towards Th2 response is observed, a non-specific pre-activation of T cells is displayed, as well as a decreased response to vaccination is seen. Moreover, an impaired function of innate immune cells indicate a predominance of zinc deficiency in the elderly that may contribute to immunosenescence. This review summarizes current findings about zinc deficiency and supplementation in elderly individuals.     

Robustness and fragility in immunosenescence

We construct a model to study tradeoffs associated with aging in the adaptive immune system, focusing on cumulative effects of replacing naive cells with memory cells. Binding affinities are characterized by a stochastic shape space model. System loss arising from an individual infection is associated with disease severity, as measured by the total antigen population over the course of an infection. We monitor evolution of cell populations on the shape space over a string of infections, and find that the distribution of losses becomes increasingly heavy-tailed with time. Initially this lowers the average loss: the memory cell population becomes tuned to the history of past exposures, reducing the loss of the system when subjected to a second, similar infection. This is accompanied by a corresponding increase in vulnerability to novel infections, which ultimately causes the expected loss to increase due to overspecialization, leading to increasing fragility with age (i.e., immunosenescence). In our model, immunosenescence is not the result of a performance degradation of some specific lymphocyte, but rather a natural consequence of the built-in mechanisms for system adaptation. This “robust, yet fragile” behavior is a key signature of Highly Optimized Tolerance.     

Oxidative stress, inflamm-aging and immunosenescence

Immunosenescence is characterized by a decreased ability of the immune system to respond to foreign antigens, as well as a decreased ability to maintain tolerance to self-antigens. This results in an increased susceptibility to infection and cancer and reduced responses to vaccination [1-5]. The mechanisms underlying immunosenescence comprise a series of cellular and molecular events involving alteration of several biochemical pathways and different cellular populations, and for the most part our understanding of these molecular mechanisms is still fragmentary. In this review we will focus on the process of senescence associated with oxidative stress, in particular how protein oxidation alters the functionality of immune cells and how oxidative stress contributes to a chronic inflammatory process often referred as inflamm-aging.     

Report on the fifth international workshop on the CCN family of genes

The Fifth International Workshop on the CCN Family of Genes was held in Toronto October 18–22, 2008. This bi-annual workshop provides a unique opportunity for the presentation and discussion of cutting edge research in the CCN field. The CCN family members have emerged as extracellular matrix associated proteins which play a crucial role in cardiovascular and skeletal development, fibrosis and cancer. Significant progress has been made in the development of model systems to tease apart the CCN signalling pathways in these systems. Results presented at the conference suggest that targeting these pathways now shows real promise as a therapeutic strategy.