The polymerase chain reaction (PCR) made it possible to detect and amplify nucleic acid target sequences of interest when present in extremely dilute quantities. Comparable target detection and signal amplification methods for proteins could dramatically improve medical diagnostics and the developing field of proteomics. In order to improve upon the sensitivity limitations of conventional ELISA assays, researchers turned to oligonucleotide-antibody conjugates where a DNA strand replaced the enzyme as the molecule responsible for the amplification of detection events. The DNA sequence bound to the antibody (Ab) becomes the surrogate for protein detection, and can be amplified with PCR in a ... Read more

Over the past decade remarkable progress has been made in identifying cytokines that promote the proliferation and differentiation of hematopoietic stem cells (HSCs) and also their co-culture with bone marrow stromal cells in vitro. Thus far, however, the relative inability to expand HSCs in vitro has greatly hindered mechanistic studies of stem cell properties and imposed limitations on the use of these cells in transplantation. This is largely due to a lack of adequate in vivo information regarding how HSCs are maintained, where HSCs reside, and the components of their microenvironment. With recent studies performed by two independent laboratories, the ... Read more

There has been a growing awarenes in recent years that tumorigenesis properties are markedly affected by the surrounding tissue microenvironment at both primary and metastatic sites. Thus, it has been shown that tumor progression is associated with extensive remodeling of adjacent tissues to provide a supportive microenvironment for cancer cell proliferation, migration, invasion, and the formation of blood vessels required for supporting cancer growth. As an example, human prostate carcinoma-associated fibroblasts can promote tumorigenic transformation in initiated human prostate epithelial cells (Olumi et al., 1999). Appreciation of the importance of the stromal response has led to the development of novel ... Read more

The exponential outburst of knowledge in molecular immunology has provided us with an in depth insight into the biological activity of cytokines. These are small, freely diffusible proteins that, together with numerous growth factors and chemokines, act as messengers by which cells of the immune system communicate with each other and with most other tissues in the body. As such, these molecules are able to regulate many aspects of the immune response in which numerous cells and tissues may be involved at any one time. Most often, cytokines are active in extremely low concentrations. It is for these reasons that ... Read more

Targeting of cytotoxic drugs, radionuclides or imaging agents to specific cells or tissues is of great interest for the development of new therapeutic strategies and diagnostic approaches. Targeting should significantly increase efficacy in the desired tissues and reduce side effects elsewhere in the body. Previously, avidin or streptavidin have been used in multistep pretargeting applications either as a fusion protein with a cancer-targeting antibody or as a linker between biotinylated cancer-targeting antibodies and biotinylated radionuclides (Wilchek et al., 1990). However, these three step strategies (i.e., cancer tissue-specific biotinylated antibody; avidin or streptavidin; biotinylated drug) are complicated to use, involve the ... Read more

In vivo techniques to investigate the pathways that mRNAs undergo from maturation to localization at specific regions within a cell have thus far been the exclusive domain of protein biology as our ability to probe for nucleic acids in vivo have been hindered (Bertrand et al., 1998). In vivo imaging of synthetic transcripts helped dissect such a fundamental cellular process. Yet, in order to fully grasp the diverse organization and behavior of mRNAs in living cells, it is important to visualize the distribution and dynamics of RNA molecules in their living context, much like green fluorescent protein and its variants ... Read more

Antisense technology is based on the principle that antisense oligonucleotides (AO) can specifically alter gene expression and the pattern of splicing at the RNA level. The first application of such technology 25 years ago was for knockdown of targeted viral gene expression (Zamecnik et al., 1978), which was achieved by targeting mRNA with AO to block the viral gene translation or induce its degradation. Such strategies have now been developed as powerful tools for the functional analysis of targeted genes in the laboratory and are suggested to be of great therapeutic potential against diseases from viral infections to cancers. More ... Read more

Two major applications exist for Nuclear Magnetic Resonance (NMR): spectroscopy and imaging. NMR spectroscopy has gained acceptance as one of the major analytical techniques, due to the detailed information that can be obtained about molecular structure, dynamics and intra- and inter-molecular interactions. Magnetic resonance imaging (MRI) is a non-invasive technique with superior soft tissue contrast and broad diagnostic value. The technique has gained wide clinical acceptance and is of great importance in diagnostic medicine. However, despite significant technological advancements (increasing field strength and cooling of electronics), the application of NMR is limited by an intrinsically low sensitivity, as compared to ... Read more

The 2001 anthrax letter mailings highlighted critical shortfalls in the USA’s capabilities for dealing with the threats of bioterrorism: the lack of effective, reliable, low-cost detection systems for use by state and local authorities. During the few months after the letters were received, 17,000 false alarms and hoaxes were reported, and Americans everywhere were terrified to open their mail. Over 200,000 samples were processed by the Center for Disease Control (CDC) and others. In a scenario where the attack was more wide spread, the laboratory processing requirements could be far greater. In light of such statistics, the imperative for high ... Read more

The Cys₂His₂ zinc finger domain (hereafter simply “zinc finger”) provides a useful scaffold for creating customized DNA-binding proteins, a technology with potential applications in biological research, molecular medicine, and gene therapy. Using a combination of targeted randomization and selection methodologies (e.g., phage display), many research groups have successfully altered the DNA-binding specificities of single zinc fingers, which typically recognize three to four base pairs of DNA. In these experiments, potential DNA-binding residues in a finger’s a-helix (or “recognition helix”) were randomized to generate a library of variants and then selection methods were used to identify fingers ... Read more