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| HEALTH & FITNESS |
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Changing a heart valve without the help of machine
How enzymes help us in keeping fit
Why blood donation is essential
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Changing a heart valve without the help of machine
Aortic stenosis is a kind of valve disease which can be caused by birth defects, though in older patients it is usually the result of calcium building up in the heart’s main valve, the aortic valve, hindering blood flow. The valve becomes tight, making the heart work harder to push oxygen-rich blood into the body. This puts a severe strain on the heart while at the same time depriving the body of oxygen. If untreated it can be fatal. The best and standard solution is valve-replacement via open-heart surgery, which involves opening up the patient’s chest, putting the heart on a bypass machine and replacing the aortic valve. While the results of this procedure are excellent — in some high risk groups — the elderly or those with severe lung disorders — the risk may be high. There is now a one-hour keyhole operation to replace the heart valve, a breakthrough which offers hope to cardiac patients too sick to undergo an open-heart surgery. The procedure called TAVI (TransCatheter Aortic Valve Implantation) is an exciting new method of minimally invasive surgery where an aortic valve is replaced over a wire either via the groin or a small chest incision without a cardiopulmonary bypass. It is at present used only in high risk cases. There is a growing group of cardiac surgeons who have excelled in the new speciality of endovascular surgery — a surgeon has the best knowledge of the anatomy to be able to change a valve without looking at it directly and can convert immediately to an open procedure in the case of complications. TAVI is usually performed in a hybrid operative suite designed and equipped to accommodate tools and personnel required for performing both open surgical and interventional procedures. TAVI procedures are best performed by a multi-disciplinary team headed by a cardio-vascular surgeon, a cardiologist and a cardiac anaesthesiologist. Other team members include a perfusionist, a surgical scrub nurse trained in transcatheter procedures, a circulating nurse, a radiology or catheterization laboratory technician and a surgical assistant. At least one member of the team must be trained in preparation and loading of the valve device, which is performed on the back table at the time of the procedure using a proprietary crimping device. In 2002, the first transcatheter aortic valve implantation was done in a human being. Since then the technique has undergone much refinement and modifications, and has emerged as a technique with great clinical significance. In future, the trained cardiovascular surgeon with endovascular skills will be a unique physician with the versatility to perform the full gamut of treatment options for aortic stenosis: open versus transcatheter aortic valve implantation (via either the transfemoral or transapical approaches). Some experts believe that in the future up to 40 per cent of aortic valve intervention may be performed utilising catheter-based techniques. At present, only two types of transcatheter aortic valve systems are available in the United States as part of clinical trials — Medtronic CoreValve Revalving device (Medtronic Inc, Minneapolis, Minnesota), and the Edwards Sapien valve (Edwards Lifesciences Inc, Irvine, California). Both systems have been well studied in human trials and are available in Europe as CE Mark approved products. The second generation Edwards Sapien platform (Sapien XT) has been introduced and it is only available in Canada and Europe at this time. In a trial — PARTNER (Placement of Aortic Transcatheter Valves) — it was concluded that TAVI should be considered as the new treatment for patients who are of too high risk for open-heart surgery. Opponents of this technique, however, argue that this is a new technique which has yet to stand the test of time. In the skilled hands of a well experienced team, the results of open surgery even in the high risk group are excellent. However, one major drawback is the exorbitant cost (about 10 times the cost of a standard surgery). In properly selected cases — where we do not have the option of open heart surgery — the procedure carries great promise for the well being of a patient who might not survive otherwise. A typical patient is usually either bed-ridden or severely short of breath and unable to do even simple household chores even on full medical therapy. The quality of life — even in an elderly patient — improves dramatically after such a successful operation. Hopefully, we will have this valve in India soon, and Punjab may be the first in Asia to use it for the benefit of patients. The writer is Head, Cardio-Vascular Endovascular & Thoracic Surgery, Christian Medical College and Hospital, Ludhiana, and is a pioneer in minimally invasive and beating heart surgery. Email: drhsbedicmc@gmail.com
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How enzymes help us in keeping fit
Proteins are critically important to life and the human body. They are also among the most complex molecules in nature, and there is much we still don’t know or understand about them. Enzymes are molecules that can trigger specific chemical reactions. Enzymes are proteins that catalyze (increase or decrease the rates of) chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and they are converted into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at significant rates. Since enzymes are selective for their substrates and speed up only a few reactions from among many possibilities, the set of enzymes made in a cell determines which metabolic pathways occur in that cell. Like all catalysts, enzymes work by lowering the activation energy (Ea‡) for a reaction, thus dramatically increasing the rate of the reaction. As a result, products are formed faster and reactions reach their equilibrium state more rapidly. Most enzyme reaction rates are millions of times faster than those of comparable un-catalyzed reactions. As with all catalysts, enzymes are not consumed by the reactions they catalyze, nor do they alter the equilibrium of these reactions. However, enzymes do differ from most other catalysts by being much more specific. Enzymes are known to catalyze about 4,000 biochemical reactions. Since the tight control of enzyme activity is essential for homeostasis, any malfunction (mutation, overproduction, underproduction or deletion) of a single critical enzyme can lead to a genetic disease. The importance of enzymes is shown by the fact that a lethal illness can be caused by the malfunction of just one type of enzyme out of the thousands of types present in our body. One example is the most common type of phenylketonuria. A mutation of a single amino acid in the enzyme phenylalanine hydroxylase, which catalyzes the first step in the degradation of phenylalanine, results in the build-up of phenylalanine and related products. This can lead to mental retardation if the disease is untreated. Enzymes are responsible for the taste of beer, the effectiveness of detergents and the digestion of food in our guts. One key challenge is the stability of enzymes, a particular type of protein that speeds up, or catalyzes, chemical reactions. Taken out of their natural environment in the cell or body, enzymes can quickly lose their shape and denature. Everyday examples of enzymes denaturing include milk going sour, or eggs turning solid when boiled. Rensselaer Polytechnic Institute Professor Marc-Olivier Coppens has developed a new technique for boosting the stability of enzymes, making them useful under a much broader range of conditions. Coppens confined lysozyme and other enzymes inside carefully engineered nano-scale holes or nanopores. Instead of denaturing, these embedded enzymes mostly retained their 3-D structure and exhibited a significant increase in activity. The discovery raises many questions and opens up entirely new possibilities related to biology, chemistry, medicine and nanoengineering, Coppens said. He envisions this technology could be adapted to better control the nanoscale environment as well as increase the activity and selectivity of different enzymes. Looking forward, Coppens and colleagues will employ molecular simulations, multiscale modelling methods, and physical experiments to better understand the fundamental mechanics of confining enzymes inside nanopores. The writer teaches chemistry at MCM DAV College for Women, Chandigarh.
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Why blood donation is essential
Blood can be defined as the red-coloured fluid we have in our body that carries oxygen from the lungs to the rest of the body. It also carries waste to be eliminated from the body. The different blood groups are: A positive or A negative B positive or B negative O positive or O negative AB positive or AB
negative Every adult has four to six litres of blood in one’s body, depending on one’s size. Of this, 350-450 ml of blood is taken out, depending on the weight of the donating person. Millions of people will need blood this year. There are lakhs of units of blood that are needed every day to help people worldwide. Some of the reasons why people need blood transfusions are: Surgery, road accidents, cancer, premature births, etc. Almost all serious health issues require blood donated by people like you and me to save lives. Blood that is donated lasts a little more than 40 days. That means we need to constantly replenish the blood so that it is there when someone needs it. Blood is in short supply usually on holidays. Maybe in the next holiday season, that could be your gift to a needy person. Our blood could save a child, a mother, a father, a grandfather or a grandmother. They cannot make blood; it is a gift we all have inside of us to give to those who are injured or sick, or are in need because of any other reason. These are the best reasons to donate blood. Not everyone can save a life. But you have an opportunity to. Don’t waste it. When you donate a unit of blood you can save the life of more than one person. Nowadays with the help of modern technologies, different blood components are prepared, which are used for different types of sick people. A healthy blood donor is a person in the age group of 18-60 years with a body weight of at least 45 kg, and having the haemoglobin content as minimum as 12.5 gm%. The main reason why people do not donate blood is because no one has asked them to do so. If you motivate people, they will come forward. Don’t hesitate. Tell them that through this noble act, they may save precious lives. Blood donation is a noble, selfless service! It gives the donor a feeling of joy and contentment. Also, this is an expression of love for mankind, as blood knows no caste, colour, creed, religion, race, country, continent or sex. The writer is a medical technologist, Blood Bank,
PGI, Chandigarh. |
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Health Notes WASHINGTON: A new study has suggested that low vitamin D levels in kids may cause anaemia, a severe condition which leads to the damage of vital organs by depriving them of oxygen. Anaemia occurs when the body has too few oxygen-carrying red blood cells, and is diagnosed by measuring hemoglobin levels. Symptoms of mild anaemia include fatigue, lightheadedness and low energy. To examine the relationship between hemoglobin and vitamin D, researchers analyzed data from the blood samples of more than 9,400 children in the 2-18 years age group. They found out that lower the vitamin D levels, lower was the hemoglobin and higher the risk for anaemia. —
ANI
Grandma was right — babies do wake up taller after a sleep!
WASHINGTON: Scientists have finally confirmed what our grandmas have been preaching over the years — babies do really wake up taller right after their sleep. Findings from the first study of its kind measuring the link between daily growth and sleep confirm that infants gain height during sleep, depending on the total hours slept and the number of sleep bouts. “Little is known about the biology of growth spurts. Our data opens the window to further scientific study of the mechanisms and pathways that underlie saltatory growth,” said lead author Michelle Lampl, from the Department of Anthropology at Emory University in Atlanta, Georgia. Researchers have found that longer sleep bouts in both girls and boys predicted an increase in weight and body-fat composition tied to an increase in length. — ANI
Wearing leggings could do more harm than good
LONDON: In what has come as a rude shock to an army of women, a new study has warned that leggings could make the muscles ‘lazy’ and can result in flabby stomachs and wobbly legs. For thousands of women, leggings have become a wardrobe staple — to hide all manner of sins whether it’s forgetting to wax or having a ‘fat’ day. “Leggings feel good and look great and I am as addicted to them as anyone, but there is a downside,” The Daily Mail quoted physiotherapist Sammy Margo as saying. “They hold in and support the quadriceps (thigh muscles), buttocks and core muscles in your tummy, and do the job the muscles are supposed to do. “As a result, the muscles are allowed to relax and switch off, so when we reveal our bodies for the first time as summer approaches, they are not as svelte or firm as they otherwise would be.” —
ANI
Any amount of alcohol can give you cancer!
MELBOURNE: In a shocking new revelation, a new report from the Cancer Council has warned that any amount of alcohol could give you cancer, regardless of your drinking levels. According to the Cancer Council, alcoholic drinks and ethanol are carcinogenic to humans and there’s no evidence that there’s a safe consumption threshold to avoid cancer, reports news.com.au. There’s convincing evidence that alcohol is a cause for cancer of the mouth, pharynx, larynx, oesophagus, bowel (in men) and breast (in women), the council said in a position statement. It’s bad news for those justifying the occasional drink as a preventer of coronary heart disease. “The previously reported role of alcohol in reducing heart disease risk in light-to- moderate drinkers appears to have been overestimated,” the council said. — ANI
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Dr Harinder Singh Bedi
