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| SCIENCE & TECHNOLOGY |
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genes to drugs by Dr Rajeev Goel The recent translation of human genome, the blueprint of life which involved deciphering billion of strands of DNA along with remarkable developments in DNA technology has furnished the medical community with many new approaches to fight against human diseases.
UNDERSTANDING
THE UNIVERSE |
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From genes to drugs Currently, the physician prescribes medicine to a patient, say of high blood pressure, which may or may not work for the first time. If it does not work the physician then tries a different drug or a dosage repeating the process till the patient improves. It may take four or five visits before the right combination of drugs is found. As pharmacogenomics becomes more advanced, the physician will no longer prescribe anti-hypertensive (blood pressure controlling) medicines through a trial and error method, but will prescribe specific antihypertensive drugs as per the individual’s genetic constitution or genotype. The medicines prescribed in such a way will not only be 100 per cent effective but will have the minimum side effects also. The physician will even be able to tell the patient that his/her hypertension is salt insensitive, which means he/she can eat salt with no adverse consequences. The goal of the pharmacogenomics is to say good-bye to trial and error method of drug therapy by creating personalised medicines i.e. tailored drug therapy (as per the genetic constitution) with greater specificity, efficacy and safety. The day is not far off when you may go in for a doctor’s visit and have your blood drawn for doing your genotype to find out which medicines would be best for you as per your genes. The significance of pharmacogenomics no doubt is to get the right prescription the first time itself. Researchers have shown that right medicine for an individual is based on small genetic variations that occur in human DNA at a frequency of one every 1000 base pairs (bases are the building blocks of DNA in the same way as bricks to the wall). These variations or SNPs (pronounced “snips”) as they are commonly called can be used as diagnostic tool to predict a person’s drug response i.e. to see whether a particular medicine will be effective or not. It is surprising to know that all humans are 99.9% genetically identical. The 0.01 per cent difference in genome sequences accounts for difference in our susceptibility to, or protection from all kinds of diseases, the age of onset and severity of illness and the way our body responds to different classes of drugs. Major drugs companies worldwide, joined by young band of pharmacogenomics companies are hunting assiduously for these small variations in the human genes that explain why drugs work well for some but not for others. The understanding of genetic variations will positively impact all aspects of medicines in the coming years. It is hoped that by the year 2030, the diagnosis of the patient illness as well as the therapy to be prescribed would be made by genomic testing using the DNA chip rather than by clinical symptoms alone. In the doctor’s clinic, biochip (DNA chip technology) would be available that would pick up the specific variations in the genes associated with a particular disease. This will help in predicting response to drugs i.e. finding out whether the patient is at risk for a bad response or no response at all to the prescribed drug therapy. Discoveries of gene variations, affecting how the drugs work in breast cancer, asthma, hypertension, diabetes point to just a few of the diseases in which pharmacogenomics will have a big impact. Once the researchers have pinpointed the genes and the associated variations responsible for these diseases, therapies for each would quickly follow. Pharmacogenomics will not be probing into small variations in the genes alone but will also be looking at the corresponding products of the genes i.e. the proteins. It is the genes that carry instructions for making chemicals called proteins. The proteins orchestrate the body’s most basic functions and are, therefore, potential drugs target too. Researchers in the field of pharmacogenomics are also using the human genome data for identifying genes that account for different drug reactions in different people. That is to say it could prevent those situations where, for example, an antibiotic may cure a throat infection in one patient but may bring another patient out in a rash. |
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Semiconducting
nanotrees
Future electronic devices could contain forests of nanoscale trees, suggests a new study by researchers in Sweden. The research builds on work with semiconducting nanowires that are being developed in many laboratories for applications ranging from computer circuits to biomedical sensors. Devices made from versatile nanowires could be faster and more powerful than today’s electronic gadgetry. In an effort to add new capabilities to nanowires, Lars Samuelson and his colleagues at Lund University in Sweden report a technique for growing treelike structures out of semiconducting materials. The Lund team first deposits gold particles that are 40 to 70 nanometers in diameter on a small wafer of gallium phosphide. The researchers then place the wafer inside a chamber and feed in a mixture of gases that supplies the raw materials for the trees. Gradually, vertical wires of gallium phosphide grow underneath each gold particle. These gold-tipped wires, measuring only a couple microns in length, serve as trunks. To create the branches, the researchers spray gold particles smaller than the original ones onto the trunks and again expose the material to the gas mixture. From each of these gold particles emerges a long branch of gallium phosphide. By controlling the size and number of the small gold particles, Samuelson and his colleagues can determine the width of each branch and the density of branches on each trunk.
‘Smoking gun’ of Giant Collision
Evidence is mounting that 251 million years ago, long before the dinosaurs dominated the earth, a meteor the size of Mount Everest smashed into what is now northern Australia, heaving rock halfway around the globe, triggering mass volcanic eruptions, and wiping out all but about 10 per cent of the species on the planet. The “Great Dying,” as it’s called, was by far the most cataclysmic extinction event in Earth’s history, yet scientists have been unable to finger a culprit as they have with the dinosaur extinction. A new paper published in Science, however, claims to identify the crater made by that meteor, and it builds upon an ongoing body of evidence by researchers at the University of Rochester and the University of California at Santa Barbara (UCSB), that points the finger for the Great Dying squarely at the heavens. |
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UNDERSTANDING THE UNIVERSE How are the comets formed? In this process a time came when the spinning material was concentrated into an ever-thinning disc. This shape was ordained by the fact that the equatorial regions of the spinning cloud could overcome the gravitational contraction while the polar regions could not. Finally, when the central core of the cloud became dense and hot inside, thermonuclear reactions started, converting hydrogen into helium and producing lot of energy. Outflow of this energy produced the outward pressure to stabilise the sun against the contracting force of gravity. Density fluctuations in the disc led to coalescence of mass into planets going around the sun. But lot of mass in the outer fringes of the thin disc escaped congregation into large masses and was retained as dispersed material in the far reaches of the solar system. It could have been kept at a distance because of the additional pressure of the solar wind. This cloud is known as the Oort cloud. The mass in the thinning edge of the pre-solar disc was too sparse to form large bodies through coagulation and was left alone to form its own small colonies. Comets could be considered as colonies of this kind and are the transformed components of the Oort cloud. They also go around the sun in long period elliptical orbits that are often perturbed when they travel into the inner solar system. In the early history of the solar system they were more frequent than now and there is a feeling that much of the water on earth and other planets was brought in by comet collisions. If the universe is expanding then what is the space into which it is expanding? One answer to your question could be that this is one of those questions that have no validity. One cannot define space without the universe. In this sense the universe expands into space that it itself creates! I know this appears confusing. But I do not know how else to answer this. Part of the problem stems from the fact that we cannot get away from images of a three dimensional non-relativistic space.
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Comets are believed to be coagulations of material left over during the formation of the solar system through gravitational contraction and spinning up of the solar nebula. (The spinning up is a consequence of conservation of angular momentum).