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| HEALTH TRIBUNE | Wednesday, August 21, 2002, Chandigarh, India |
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Smallpox vaccination questioned
Food allergens INFO CAPSULE
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Cardiac surgery & diabetics: the challenges Diabetes mellitus is an established risk factor for the development of coronary artery disease. Epidemiological data from the Framingham and other studies have clearly documented this fact. Coronary artery disease (CAD) is 2-3 times higher in diabetics than non-diabetics — the risk being further higher in women. Accelerated coronary and peripheral arterial atherosclerosis (deposition of cholesterol in the arteries) is one of the most common and serious chronic complications of long-term diabetes. The factors contributing to the increased risk are alterations in platelet function, clotting factors, arterial smooth muscle cell metabolism and blood pressure regulation, and changes in plasma lipoprotein metabolism. CAD is not only more prevalent in diabetics but is also more extensive, involves more vessels and is progressive. The risk multiplies if hypertension is associated with diabetes, a not uncommon combination. Diabetic patients coming for CABG are generally older, comprise more women, have a greater incidence of hypertension and previous heart attack have a worse class of angina (chest pain), have a higher incidence of heart failure and suffer from a severe disease in all three vessels of the heart. It is well known that there is a much higher rate of restenosis after ballooning (PTCA) and stent placement in diabetics. Insulin dependent diabetics are worse than non-insulin dependent ones. Diabetes mellitus is an established independent risk factor for significant morbidity and mortality after bypass surgery. Diabetics have a higher incidence of post-operative death and stroke, pri-operative heart attack, infections (deep sternal wound infection — DSWI — and leg wound infection), greater morbidity from the use of arterial grafts, a lower freedom from post-operative angina, greater attrition of vein grafts and a lower long-term survival. Thus diabetes has a negative impact on short-and-long-term survival after CABG. The poor long-term results may be because of the additional effect of abnormalities in vascular endothelium. Diabetics have an abnormal endothelium dependent vasodilatation both in conduits and in resistance vessels due to a reduction in the synthesis and release of nitric oxide — an endogenous vasodilator. Hyperglycemia (high blood sugar) in the immediate post-operative period constitutes one of the most important predictors for the development of infection. Hyperglycemia impedes the normal physiologic responses to infection and prevents the white blood cells from destroying the invading bacteria. Hyperglycemia also impedes normal healing processes by increasing collagenase activity and decreasing wound collagen content. Interestingly, all these abnormalities can be reversed with the control of blood glucose levels. The socio-economic costs of infection, especially deep sternal wounds (DSWI), are staggering. One large study in Portland, Oregon, USA, found that a single DSWI cost an additional $ 26,400 and increased the average length of stay by 16 days. Psychological morbidity from pain, suffering and altered body image is immeasurable. There was an increase in mortality from DSWI by five times (19 per cent vs 3.8 per cent) in the Portland series. Thus, diabetics constitute a very challenging subset of patients coming for CABG. The surgeon is faced with the dilemma of either using “simple” conduits (saphenous vein graft) to reduce the risk of DSWI or using arterial grafts to improve long-term survival at the risk of an early sternal infection. The malignant nature of the atherosclerosis in diabetics makes it mandatory to adopt an aggressive approach to combat the genesis of infection while at the same time not compromising on the conduits used in order to have better long-term results. The cardiac scientist has risen to the challenge by using methods for better control of diabetes, better technique of harvesting the internal mammary artery, use of minimally invasive techniques to harvest the saphenous vein, use of off-pump techniques to avoid the heart-lung machine with all its attendant side-effects (immunological, hematological, neurological, pulmonary, renal hepatic, psychological), development of robotic techniques for CABG and endoscopic vein harvesting techniques. It has been proved beyond doubt that the best way to reduce graft attrition and hence the need for a second bypass surgery is the use of arterial grafts. This becomes even more important in a diabetic who genetically has a more severe and malignant atherogenic propensity and has probably already got blocked stents from previous PTCA (ballooning). We continue to aggressively use arterial grafts in diabetics but with some modifications to lower the degree of reduced blood supply to the sternum which is inherent with the harvesting of the internal mammary artery — IMA — the artery behind the breast bone. We use a special technique of semi-skeletonisation or skeletonisation of the IMA. As opposed to standard techniques of harvesting, the devascularisation of the sternum is much less (proven by post-operative nuclear scans of the sternum). We can then selectively use both the IMA (left and right). Alternately, we sometimes take down a short length of the right IMA and extend it with a radial artery or a vein (composite graft) to get the advantage of an arterial conduit without sacrificing the blood supply of the sternum. We are now using the radial artery (single from the non-dominant hand or bilateral) in almost 95 per cent cases. This has been used by the author for over seven years with excellent mid-term patency results. The results are very close to those of the IMA and much better than of vein grafts. If still more arterial conduits are required we harvest the right gastro-epiploic artery (RGEA) — artery from the stomach — or the inferior epigastric artery (IEA). These give excellent long-term results but are a bit more tedious to harvest. The writer is a senior consultant and cardiovascular and thoracic surgeon, Fortis Heart Institute, Mohali.
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Smallpox vaccination questioned A
recent (May 30, 2002) New Scientist report based on a paper published in Maryland Medicine (Spring, 2002) brings very bad news. The paper asserts that if you had a smallpox vaccination as a child and think that you are protected, you are in for surprise. The study covered the immunity of 621 microbiologists in Maryland, USA. They received fresh vaccination against smallpox between 1994 and 2001. Vaccination is mandatory for them for protection at work. The study revealed that only 40 of them are immune to smallpox now. The immunity is not as durable as we thought earlier. In the US 60 per cent had vaccination. It is unbelievable that they are as vulnerable as the 120 million people born since 1972, when the government stopped vaccination. A previous study suggested that immunity could last 50 years or more. An Israeli study in 1990 also showed that immunity would last several decades. These assurances are no more valid now. The best way to contain an outbreak is to vaccinate everyone. Mass vaccination has its own perils. Andy Coghlan reports in New Scientist, that if we extrapolate from the results of the mass vaccination in 1968, 180 persons may die of complications. The US Center for Disease Control believes that mass vaccination is unnecessary. And it can deal with an outbreak through “ring vaccination” of people in the affected zone and their contacts. The fact that smallpox will kill 30 per cent of the patients is very uncomfortable. We cannot dismiss the possibility of bioterrorism in the light of recent experience with anthrax in the USA. The government wants scientists to go back to their earlier studies to look for more effective weapons against bioterrorism.
Joys of food
Scientists from the Brookhaven National Laboratories could objectively measure food stimuli in hungry volunteers by using Positron Emission Tomography (PET) scans of their brains. The study appears in the latest issue of the journal Synapse. They measured the baseline dopamine levels of 10 hungry volunteers by subjecting their brain to a PET scan. Dopamine is a neurotransmitter — a sort of message carrying chemical. It is associated with pleasure. Scientists asked the volunteers what there favourite foods were. Then they got into a discussion about their family tree. They did it intentionally. The topic is obviously unappetising. During the session, they measured their baseline dopamine levels. Then they showed them their favourite food. They ensured that they could not eat it. Their dopamine levels shot up. Dr Nora Volkow, the leader of the team, stated that it is perfectly normal. It is nature’s mechanism to direct us to eat when food is available. When the human being evolved there were no “24 hour food shops” available. They had to eat when food was available. Scientists gave the volunteers Ritalin — a drug used to treat children suffering from attention-deficit hyperactivity disorder. Ritalin enhances the effects of dopamine on the brain. The response of the volunteers to food amplified. Scientists did not expect this. Children do not want to eat while they are on Ritalin. Dr Volkow believes that Ritalin increases appetite only when food is presented under abnormal circumstances. My son as many other sons refuses to eat when food was given to him. My wife used to place small amounts of food on a spoon, pretending that the spoon was flying in from somewhere and ask him to eat. He ate readily because of the variety of delivery!
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Food allergens New food allergens have been recognised recently in plants belonging to PR-14 (pathogenesis related) protein. These are produced in plants due to the stress caused by insecticide sprays, chemical and genetic modifications and environmental changes. To name a few: PR2 and PR4 in banana; PR3 in chestnut (singhara); PR4 in turnip and potato; PR5 in cherry, apple, bell pepper, peach; PR10 in apricot, pear, carrot, peach, apple, soyabean; PR 14 in plum, cherry, barley and apricot. This does not mean that these foods should be avoided by an asthmatic. The message is that even respiratory and skin allergies are increasingly being attributed to food allergens, and new allergens are being recognised in everyday food. But avoiding food just on presumption or by hit and trial will prove disastrous. Allergy tests and consultation with allergy specialists must be done for the scientific treatment of these diseases. The writer is an allergy specialist and paediatrician. |
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INFO
CAPSULE Gangtok: A recent study has shown the prevalence of stomach cancer to be highest among Sikkimese people. As estimated 10.4 per cent of Sikkimese were found afflicted with stomach cancer, according to a study by Dr Yogesh Verma, a consultant physician at the state-run STNM Hospital, the only referral hospital in the state. The prevalence of cancer in oesophagus (the passage from the pharynx to the stomach) stood at 9.45 per cent, breast 8.45, cervix 7.5, liver 6.0 and oral cavity 4.5 per cent in Sikkim, the study said. The doctor and his team made the study on 201 people drawn from all walks of life at different clinics across the state.
PTI New vaccine for malaria London: Adopting an innovative approach, a team of scientists from Oxford University has pioneered a vaccine against malaria that can save millions of lives, particularly in developing countries. "The vaccine is safe, it is working and we are seeing protection in humans, which is tremendous. We are encouraged", Adrin Hill, a professor from Oxford University's Department of Medicine who is heading the project, said. The vaccine's target is plasmodium falciparum, the most dangerous of four types of malaria. The parasite can affect brain and is responsible for 99 per cent of malaria deaths. It works by seeking to stimulate a different part of the body's immune system to that which other vaccines focus on.
PTI Smoking takes toll on economy Singapore: Smokers cost the Singapore economy 839 million Singapore dollars (479 million US dollars) a year in lost working time due to illnesses and deaths, a new study has showed. The findings published in The Straits Times took into account the higher medical bills produced by smokers. "We wanted to account for how much smoking is costing Singapore", said Professor Euston Quah from the National University of Singapore's Economics Department. "IT is not a low figure." Men, who make up the majority of smokers in the city - state of 3.5 million people, were responsible for 90 per cent of smoking costs, said the study, which started in 1999.
DPA |
Cardiac surgery & diabetics: the challenges
Problems like asthma, nose-related difficulties, sinusitis, pain in the abdomen, skin rashes and itching can be due to food allergy.