Alcohol's effects on gene expression in the central nervous system

Alcohol's primary target is the central nervous system (CNS), where it influences neurotransmission to produce intoxication. Scientists can now use microarray technology to study brain function gene by gene. Symposium proceedings published in the February issue of Alcoholism: Clinical & Experimental Research address the effects of alcohol on what is called "gene expression" in the CNS regions of animal models.
"All of our cells have exactly the same deoxyribonucleic acid (DNA), which means they all have the same genes," explained William J. McBride, symposium organizer and professor of neurobiology at the Indiana University School of Medicine. "The reason that different cells can appear and work so differently with the same genes – giving us, for example, unique eyes, skin, or hair – is that only some genes are used or 'turned on' in each cell. This is called gene expression."
McBride said that researchers now know that alcohol can change gene expression in the brain, and that these changes are likely responsible for many of the 'symptoms' of addiction, such as tolerance, physical dependence, and craving, as well as the 'consequences' of alcoholism, such as brain damage.
"The challenge has been to find out which genes – out of more than 50,000 – are turned on or off in the brains of alcoholics," he said. "Microarray studies – the examination of a small glass microscope slide that has thousands of different DNA samples attached to it – that are applied to brain function are just beginning in the field of alcoholism. Several years ago, it was impossible to analyze more than a handful of these genes, however, microarray technology has changed that."
Symposium speakers at the June 2004 Research Society on Alcoholism meeting in Vancouver, B.C. presented the following findings from recent studies that used genetic animal models:


# Gene expression profiling in the nucleus accumbens, prefrontal cortex, and ventral tegmental areas show that distinct biological pathways are associated with alcohol's action in specific brain regions and certain mouse strains.


"We were able to use gene expression profiling to determine that alcohol produces multiple effects on different biological processes," said McBride, "and that these changes are different in several brain regions which may be involved in alcohol addiction."


# Researchers have identified individual genes and gene networks that may play an important role in determining the behavioral responses to alcohol as well as possibly influencing drinking behavior.


"Thus far, genes that appear to be responsive to alcohol include genes involved in the intracellular signaling process (which can alter how the neuron functions), neuropeptide signaling (which modulates nerve cell activity), and myelin structure (which is needed for communication between nerve cells)," said McBride. "Gene expression profiling has also been used to identify chromosomes and chromosomal regions that influence alcohol drinking and response to alcohol."


# Intracranial self-administration of ethanol into the posterior ventral tegmental area (VTA) of alcohol-preferring rats produced results suggesting that the reinforcing effects of alcohol are activating VTA dopamine neurons and producing changes in synaptic connections that resemble those that occur in memory and learning.


"Learning and memory require enhanced synaptic function between neurons," explained McBride. "Enhanced synaptic function is characterized by increased formation of synaptic proteins. The stimulation of VTA dopamine neurons by alcohol increases the expression of genes involved in the synthesis of synaptic proteins in target regions of the VTA. In short, these results suggest that alcohol can produce changes in the brain reward system that can further increase the rewarding effects of alcohol."


# Microarray techniques confirmed earlier reports indicating that chronic alcohol exposure/withdrawal differentially alters gene expression in the prefrontal cortex of mice. More than 300 genes were found to be altered by acute alcohol treatment.


"The prefrontal cortex is involved in motivated behaviors," noted McBride. "Studies with humans indicate that this brain region is sensitive to the effects of heavy alcohol drinking and repeated withdrawals. The microarray technique provides insight into cellular changes that occur over time with chronic alcohol drinking and repeated withdrawals."


Collectively speaking, added McBride, findings presented at the symposium demonstrate the quantitative and qualitative applications of microarrays to studying the genetic and biological bases of alcoholism and alcohol abuse within discrete brain regions.
"For researchers, microarray technology has the potential of studying the genetic and biological bases of alcohol's rewarding effects, sensitivity to the effects of alcohol, development of tolerance to the effects of alcohol, development of alcohol dependence, and alcohol withdrawal severity," he said. "For the average reader, knowing which genetic profiles might contribute to excessive alcohol drinking could be used to identify risk factors that contribute to alcoholism and alcohol abuse, and could aid in the development of selective treatment strategies for different subgroups of alcoholics."
McBride added that, despite recent advances, researchers need further developments in microarray technologies and bioinformatic approaches to better understand the complex neurobiological mechanisms underlying alcohol addiction. "Future research will need to determine changes in gene expression in very discrete neuronal pathways that may be involved in mediating the effects of alcohol that lead to addiction," he said. "Future studies will also require the integrative efforts of many investigators working with different animal models in order to identify the multiple genetic factors that contribute to the risk for alcoholism and alcohol abuse."

Source : Indiana University School of Medicine

potentials of nanotechnology

Back in September 2004, the US National Cancer Institute (NCI) launched the Alliance for Nanotechnology in Cancer to stimulate and coordinate research in biology, engineering and materials science to push cancer nanotechnology forward. Just over 2 years on, such research is attracting increasing attention: in a round-up of last year's breakthroughs in the burgeoning field of nanotechnology from Forbes magazine, anticancer nanoparticles featured in the top five.

Nanotechnology is being applied to cancer in two broad areas: the development of nanovectors, such as nanoparticles, which can be loaded with drugs or imaging agents and then targeted to tumours, and high-throughput nanosensor devices for detecting the biological signatures of cancer. Combined, such technologies could lead to earlier diagnosis and better treatment for patients with cancer.

Spearheading efforts to expedite the clinical application of these technologies, the NCI currently funds eight Centers of Cancer Nanotechnology Excellence (CCNE) in the United States, in addition to 12 other smaller programmes. "We've pulled most of the key players in medical nanotechnology into this programme, and we're spending about US$35–40 million a year on these approaches," says Piotr Grodzinski, Director of the NCI Alliance. The NCI Alliance is actively pursuing both the therapeutic and diagnostics aspects of cancer nanotechnology with follow-up programmes in sight. Grodzinski hopes that by then nanotechnology will have matured into a clinically useful approach.


Robert Langer's team have shown the potential of targeted nanoparticles to deliver anticancer drugs.
Early signs are promising. The research highlighted in the Forbes list was conducted by a team led by Robert Langer, a chemical engineer who is Institute Professor at the Massachusetts Institute of Technology (MIT), USA, and also one of the two principal investigators for the MIT–Harvard CCNE. Langer, with Omid Farokhzad, Assistant Professor of Anaesthesia at Brigham and Women's Hospital, Boston, USA, and colleagues, uses polymeric nanoparticles coated with aptamers — RNA-based targeting moieties — to guide them towards the tumour, where they bind, enter the cells and then dissolve to spill out their contents — the anticancer drug docetaxel. The nanoparticles are also coated with polyethylene glycol (PEG) to aid their safe passage through the bloodstream and into the tumour cells. A single injection of such nanoparticles coated with aptamers that bind to prostate-membrane-specific antigen eradicated tumours in a mouse model of prostate cancer (PNAS 103, 6315–6320; 2006). "Extensive animal models show that this approach is both safe and efficacious," says Langer.

One of the key challenges in creating effective nanoparticles is targeting them to appropriate tissues and cells. Although biological targeting using aptamers or antibodies on the surface of nanoparticles is one popular option, other researchers are beginning to exploit the physical characteristics of the particles to guide them to desired locations. "The size, shape, physical properties, density and charge all affect how particles travel through the body, and whether or not they will cross biological membranes," says Mauro Ferrari, a professor of nanotechnology at the University of Texas Health Science Center, the M.D. Anderson Cancer Center, and Rice University in Houston, USA. His work shows that biological barriers such as the vascular wall dominate the distribution of injected nanoparticles in the body, even for particles that are decorated with exquisite biological recognition moieties. A judicious choice of size and shape of a nanovector particle can enhance by orders of magnitude the amount of drug delivered to the target lesion site. "I believe that the era of 'rational design' of nanoparticles has arrived, and that optimal design will occur based on principles of engineering and physics," Ferrari says.


Joseph DeSimone, professor of chemistry and chemical engineering at the University of North Carolina at Chapel Hill, USA, is putting these principles into practice. DeSimone has adapted fabrication technologies from the electronics industry to produce shape-specific organic nanoparticles. "We basically make moulds out of a really low-surface-energy fluoropolymer that allows us to synthesize truly engineered particles with desired characteristics," says DeSimone. DeSimone's engineered process allows the precise control over particle size (20 nm to >100 m), particle shape (spheres, cylinders, discs, toroidal), particle composition (organic or inorganic, solid or porous), particle cargo (hydrophilic or hydrophobic therapeutics, biologicals, imaging agents), particle compliance (stiff, deformable) and particle surface properties (Avidin–biotin complexes, targeting peptides, antibodies, aptamers, PEG chains).

Nanoparticles are not the only way to encapsulate a drug or imaging agent into a small carrier, but DeSimone suggests that the nanotechnology approach offers crucial advantages. "With liposomes [which have previously been used to deliver drugs] you kinetically trap what cargo molecule you can, but you can't modify the amount that gets trapped," says DeSimone. "Our moulds enable us to make organic particles loaded with therapeutic cargoes at any amount — 5%, 20% or whatever we want."

DeSimone is also taking a cue from naturally occurring particles, such as red blood cells, to produce compliant nanoparticles that can deform to pass across biological barriers such as sinusoids in the spleen or the blood–brain barrier. "The ability to get through these barriers and the flow characteristics of particles — whether they flow through the centre of a capillary or along cell walls — are dictated by size, shape, surface chemistry and compliance," says DeSimone.

Liquidia Technologies Inc., based in Morrisville, North Carolina, USA, was spun-off from DeSimone's laboratory a few years ago to develop this technology platform. Right now, the company is working on feasibility studies, as well as research collaborations with some large pharmaceutical and medical device companies. "These feasibility studies will run through the rest of 2007, with the goal of focused out-licensing and joint product development deals within the next 18 months," says Luke Roush, Vice President of Business Development at Liquidia. "These studies will also provide data that will validate application of our technology platform, and help us advance knowledge about how to apply it in areas of clinical need," adds Roush.

The synergy between the therapeutic and diagnostic/monitoring applications of nanotechnology could be particularly potent. Linda Molnar, a programme officer at the NCI Alliance, sees a future in which new imaging agents, new diagnostic chips and new targeted therapies come together to facilitate a form of personalized medicine in which early and more accurate detection leads to rapid initiation of treatment, followed by diagnostic tests to see whether the patient is responding. If they do, good; if not, another therapy can be tried and the process repeated — what Molnar refers to as real-time therapeutic monitoring. "The sooner you can detect the cancer and start treatment, and know that you're treating that patient with a therapy that they respond to, the better," says Molnar. "That's why people are excited, and why people at the NCI have made such a large investment in nanotechnology for cancer."

As novel nanomedicine products move from the laboratory to the clinic, the issue of regulatory approval of these new technologies will come to the fore. In many cases these products will combine established drugs with materials already used in FDA-approved therapies, and no special provisions are in place to deal with nanomedicine at present. An FDA spokesperson said, "All nanotechnology applications will at this point fall within the existing framework for review of all products submitted to CDER [Center for Drug Evaluation and Research]; [however], CDER is discussing how nanotech products may be treated differently, if necessary."

role of nanotechnology in biology

Nanotechnology refers to the interactions of cellular and molecular components and engineered materials—typically clusters of atoms, molecules, and molecular fragments—at the most elemental level of biology. Such nanoscale objects— typically, though not exclusively, with dimensions smaller than 100 nanometers—can be useful by themselves or as part of larger devices containing multiple nanoscale objects. At the nanoscale, the physical, chemical, and biological properties of materials differ fundamentally and often noninvasive access to the interior of a living cell affords the opportunity for unprecedented gains on both clinical and basic research frontiers.
unexpectedly from those of the corresponding bulk material because the quantum mechanical properties of atomic interactions are influenced by material variations on the nanometer scale. In fact, by creating nanometer-scale structures, it is possible to control fundamental characteristics of a material, including its melting point, magnetic properties, and even color, without changing the material’s chemical composition.

Nanoscale devices and nanoscale components of larger devices are of the same size as biological entities. They are smaller than human cells (10,000 to 20,000 nanometers in diameter) and organelles and similar in size to large biological macromolecules such as enzymes and receptors— hemoglobin, for example, is approximately 5 nm in diameter, while the lipid bilayer surrounding cells is on the order of 6 nm thick. Nanoscale devices smaller than 50 nanometers can easily enter most cells, while those smaller than 20 nanometers can transit out of blood vessels. As a result, nanoscale devices can readily interact with biomolecules on both the cell surface and within the cell, often in ways that do not alter the behavior and biochemical properties
of those molecules. From a scientific viewpoint, the actual construction and characterization of nanoscale devices may contribute to understanding carcinogenesis.
Noninvasive access to the interior of a living cell affords the opportunity for unprecedented gains on both clinical and basic research frontiers. The ability to simultaneously interact with multiple critical proteins and nucleic acids at the molecular scale should provide better understanding of the complex regulatory and signaling networks that govern the behavior of cells in their normal state and as they undergo malignant transformation.

Nanotechnology provides a platform for integrating efforts in proteomics with other scientific investigations into the molecular nature of cancer by giving researchers the opportunity to simultaneously measure gene and protein expression, recognize specific protein structures and structural domains, and follow protein transport among different cellular compartments. Similarly, nanoscale devices are already proving that they can deliver therapeutic agents that can act where they are likely to be most effective, that is, within the cell or even within specific organelles. Yet despite their small size, nanoscale devices can also hold tens of thousands of small molecules, such as a contrast agent or a multicomponent diagnostic system capable of assaying a cell’s metabolic state, creating the opportunity for unmatched sensitivity in detecting cancer in its earliest stages. For example, current approaches may link a monoclonal antibody to a single molecule of an MRI contrast agent, requiring that many hundreds or thousands of this construct reach and bind to a targeted cancer cell in order to create a strong enough signal to be detected via MRI. Now imagine the same cancer-homing monoclonal antibody attached to a nanoparticle that contains tens of thousands of the same contrast agent—if even one such construct reaches and binds to a cancer cell, it would be detectable.

Chromosomal DNA OPTICAL TWEEZERS

Optical tweezers uses light to manipulate microscopic objects as small as single atom.the radiation pressure from a focused laser beam able to trap these smaller particles.in biology these instruments have apply force in PN-range(pico newton) to measure displacement in the nm range of objects ranging in science from 10 nm to over 100nm.optical tweezers instruments will help in all aspects of biology such as to interaction between the cells.optical tweezers have wide applications in various fields especially in aspects of biology.in transported along microutubules,cell manipulation include cell orientation in microscopic analysis,as well as stretching the cells,to diagnose and treat blood clot,red cells in fertility treatment like sperm motility,as molecular motors,studying DNA drug interaction,unzipping the DNA,and to unravel the bacterial chromosomes.

Nanocapsule-a new nuclear weapon.

Nanocapsule are sub-microscopic collodial drug carrier system composed of an oily or an aqueous core surrounded by a thin polymer membrane.two technologies can be used to obtain such Nanocapsules:the interfacial polymerization of a monomer or the interfacial Nanodeposition of a preformed polymer.

BRAIN to control 'HUMAN BRAIN'

At present situation bioinformatics play a vital role in the field of life sciences.nothing can be done without the help of computers in biological field.researchers depend on biological databases. The uncontrollable growth of bioinformatics paves the way for the emergent of its several branches like immuno-informatics,chemi-informatics etc...

one such an awful field is "neuroinformatics".neuroinformaticscomprises both the neuroscience datas and application of computational models and the possibilities for interoperability between and among databases,models,networks,technologies and models for the clinical and research purposes in the neuroscience community and other fields.neuroinformatics uses databases,the internet,and visualization in the storage and analysis of the neuroscience data such as molecular and cellular data,data from organs and system,cognitive data,developmental information,information about disease and again,neural engineering data,computational neuroscience data.it provides the functional controls and the structural informations about the brain.in simple words,it gives each and every information about the neuron network.several projects are going on based on the datas provided by neuroinformatics.it creates a new way to avoid or solve the problems related to the nervous system.thus neuroinformatics has started to control the behavior of the human brain.

Peptidomimetics-a potential promise for drug discovery.

A Peptidomimetic is a compound with non-Peptidic structural elements that can imitate or block the biological effect of a Peptide at receptor level.Peptidomimetics invoke both structure and function.Peptides as a such are associated with remarkable biological properties,but prone to proteolytic digestion and show delivery hindrance in pharmaceutical applications.peptidomimetics improve stability,specificity and bio-availability.peptidomimetic has potent application as drugs,neurotransmitters,hormones and physiological modulators.this technique s applied widely in cancer treatment and antiviral drug discovery.

DNA microarray data analysis.

Microarray technology evolved from southern blotting, where fragmented DNA is attached to a substrate and them probed with a known gene or fragment.the use of a collection of distinct DNA's is array for expression profiling was first described in 1987,and the arrayed DNA were used to identify genes whose expression is modulated by interferon.

There early gene array were made by spotting cDNA onto filter paper with a pin-spotting device.the use of miniaturized microbarrays for gene expression profiling was first reported in 1955 and a complete eukaryotic genome 'saccharomyces cerevisiae' on a microarray was published in 1977.


A DNA microarray is a multiplex technology used in molecular biology and in medicine.it consists of an arrayed series of thousand of microscopic spots of DNA sequencs.this can be a short section of a gene or other DNA element that are used as probes to hybridize a cDNA or cRNA sample(called target) under high-stringency conditions.probe-target hybridization is usually detected and quantified by detection of fluorophoqe-silver or chemiluminescence-labelled targets to determinne relative abundance of nucleic acid sequence in the target.

In standard microarrays,the probe are attached to a solid surface by a covalent bond to a chemical matrix (via epoxy-silane,amino-silane).the solid surface can be glass or a silicon chip.they are commo known as gene chip or colloquially affy chip.other microarray platforms,such as illumina,use microscopic beads,instead of large solid support.DNA arrays a different from other types of microarray only in that they either measure DNA or use DNA as part of its detection system.

DNA microarray can be used to measure changes in expression levels,to detect single nucleotide polymorphism in genotyping or in resequencing mutant genomes.microarray also differs in fabrication,workins,accuracy,efficiency and cost.additional factors for microarray experiments are the experimental designs and the methods of analyzing the data.