Part C

In this part of the test, there are two texts about different aspects of healthcare. For questions 7-22, choose the answer (A, B, C or D) which you think fits best according to the text.

Text 1: Allergic to eating

Lucy Smith was strolling through Canberra last July. Within moments she couldn’t stand, gripped by pain so severe she feared she would pass out – the first sign of paralysing diarrhoea. This dramatic episode turned out to be caused by a newly-acquired food allergy – to red meat. Food allergies affect one per cent of the adult population of Australia. Most don’t hit with the same force as Lucy’s, but the physical and mental impact can nonetheless turn a person’s life upside down, and may even be life-threatening. Lucy deduced that she was allergic to red meat, one of the less common allergenic foodstuffs. Only after several further attacks of varying severity, was her suspicion eventually confirmed by a specialist.

An allergy, according to immunologists, is the immune system over-reacting to a substance that would ordinarily be considered benign. However the term ‘allergy’ is used more loosely by the general public. People say they are allergic to a substance because it brings about some kind of adverse reaction in their bodies, some of which can be severe and may resemble true allergic reactions, but unless the immune system itself is directly involved, experts categorise it as ‘intolerance’. Constant sneezing, itchy eyes or throat and inner ears, asthma, rashes, and diarrhoea can all be signs of food allergies. Intolerance can bring on similar warning signs as well as things such as headaches, bloating, and general lethargy. Over time, some allergy sufferers lose weight because there are so few foods they can eat. Of course the social implications are huge too – eating is a major social event.

To diagnose a food allergy, immunologists use a ‘skin-prick test’ in which a drop of a commercially extracted allergen is placed on the skin and the first couple of skin layers are pricked with a lancet. If a person is allergic, the immune system is stimulated sufficiently to produce a mosquito bite-like bump within fifteen minutes. This testing method is, however, somewhat unreliable in detecting intolerances, because, while not fully understood, they operate via a different biological mechanism possibly involving chemicals in food irritating nerve endings in the body. They are generally diagnosed by following an exclusion diet in which suspect foods are gradually reintroduced and their effects monitored.

According to paediatric immunology specialist Dr Velencia Soutter, around six to eight per cent of babies are affected by allergy. While most children will outgrow them, some actually grow into them. The mechanisms that provoke an allergy remain a grey area. Soutter says: ‘It’s like throwing a match into a fireworks factory. Hit the right place and you set off a chain reaction. Miss it and the match just fizzles out. That difference between lighting up or fizzling out isn’t well understood.

Broadly speaking, Dr Soutter says the ideal recipe for a food allergy is to be born of allergic parents and then to have a high exposure to an allergenic foodstuff. But there are so many exceptions to this rule that other forces are clearly at work, and who’s to say what ‘high’ exposure is anyway? In contrast, the so-called hygiene hypothesis suggests too low an exposure to allergens is to blame. The idea is that today’s clean environments leave our immune systems with too little to do, encouraging them to turn on the wrong culprits. Clearly, the field of immunology has only just scratched the surface of understanding.

Interesting flakes of information are gradually being peeled off that surface, however. There is evidence that allergens can be transferred through a mother’s breast milk to her child, and possibly also through the placenta. Since the immaturity of babies’ immune systems might make them more vulnerable to an inherited allergic tendency, women in allergic families could be advised to avoid certain foods during pregnancy and breastfeeding. It is possible, though, that some allergies or intolerances are purely imaginary and this can also have consequences for children. One US study found that parents sometimes avoided foods to which they erroneously believed their children were allergic, occasionally leaving the children severely underfed.

In Australia, the number of people with genuine and severe allergies is growing. Some doctors speculate whether the increased amount of new chemicals in the environment and in food is perhaps damaging immune systems–making them more prone to react adversely. Much more research needs to be done to provide evidence for that hypothesis. Anecdotally though, some experts say that staying off processed foods resolves the problem in a significant number of cases. Dr Soutter speculates that a rise in peanut allergy cases makes up the bulk of the increase in food allergies. Greater exposure has probably allowed more peanut allergies to flourish, she thinks. Peanut consumption per capita is rising. It’s a common ingredient in Asian and vegetarian dishes, which have grown in popularity, and the diet-conscious population is increasingly turning to nuts as a source of healthy fats.

Text 1: Questions 7-14

1. The case of Lucy Smith highlights the fact that food allergies

2. In the second paragraph, what point is made about food intolerances?

3. The phrase ‘via a different biological mechanism’ in the third paragraph explains

4. Dr Soutter uses the image of a fireworks factory to illustrate that

5. In the fifth paragraph, what point is made about the two hypotheses mentioned?

6. What does the phrase ‘this rule’ in the fifth paragraph refer to?

7. What does the sixth paragraph suggest about the transference of allergies between mother and child?

8. Dr Soutter suggests that the rise in cases of one allergy may be partly due to

Text 2: Prenatal origins of heart disease

Heart disease is the greatest killer in the developed world today, currently accounting for 30% of all deaths in Australia. A concept which is familiar to us all is that traditional risk factors such as smoking, obesity, and genetic make-up increase the risk of heart disease. However, it is now becoming apparent that another factor is at play – a developmental programming that is predetermined before birth, not only by our genes but also by their interaction with the quality of our prenatal environment.

Pregnancies that are complicated by sub-optimal conditions in the womb, such as happens during pre-eclampsia or placental insufficiency, enforce physiological adaptations in the unborn child and placenta. While these adaptations are necessary to maintain viable pregnancy and sustain life before birth, they come at a cost. The biological trade-off is reduced growth, which may in turn affect the development of key organs and systems such as the heart and circulation, thereby increasing the risk of cardiovascular disease in adult life. Overwhelming evidence in more than a dozen countries has linked development under adverse intrauterine conditions leading to low birth weight with increased rates in adulthood of coronary heart disease and its major risk factors – hypertension, atherosclerosis and diabetes.

The idea that a foetus’s susceptibility to disease in later life could be programmed by the conditions in the womb has been taken up vigorously by the international research community, with considerable efforts concentrating on nutrient supply across the placenta as a risk factor. But that is just part of the story: how much oxygen is available to the foetus is also a determinant of growth and of the risk of adult disease. Dr Dino Giussani’s research group at Cambridge University in the UK is asking what effect reduced oxygen has on foetal development by studying populations at high altitude.

Giussani’s team studied birth weight records from healthy term pregnancies in two Bolivian cities at obstetric hospitals and clinics selectively attended by women from either high-income or low-income backgrounds. Bolivia lies at the heart of South America, split by the Andean Cordillera into areas of very high altitude to the west and areas at sea-level to the east, as the country extends into the Amazon Basin. At 400m and almost 4000m above sea-level, respectively, the Bolivian cities of Santa Cruz and La Paz are striking examples of this difference.

Pregnancies at high altitude are subjected to a lower partial pressure of oxygen in the atmosphere compared with those at sea-level. Women living at high altitude in La Paz are more likely to give birth to underweight babies than women living in Santa Cruz. But is this a result of reduced oxygen in the womb or poorer nutritional status?

What Giussani found was that the high-altitude babies showed a pronounced reduction in birth weight compared with low-altitude babies, even in cases of high maternal nutritional status. Babies born to low-income mothers at sea-level also showed a reduction in birth weight, but the effect of under-nutrition was not as pronounced as the effect of high altitude on birth weight; clearly, foetal oxygenation was a more important determinant of foetal growth within these communities. Remarkably, although one might assume that babies born to mothers of low socio-economic status at high altitude would show the greatest reduction in birth weight, these babies were actually heavier than babies born to high-income mothers at high altitude. It turns out that the difference lies in ancestry.

The lower socio-economic groups of La Paz are almost entirely made up of Aymara Indians, an ancient ethnic group with a history in the Bolivian highlands spanning a couple of millennia. On the other hand, individuals of higher socio-economic status represent a largely European and North American admixture, relative newcomers to high altitude. It seems therefore that an ancestry linked to prolonged high-altitude residence confers protection against reduced atmospheric oxygen.

Giussani’s group also discovered that they can replicate the findings observed in Andean pregnancies in hen eggs: fertilised eggs from Bolivian birds native to sea-level show growth restriction when incubated at high altitude, whereas eggs from birds that are native to high altitude show a smaller growth restriction. Moving fertilised eggs from hens native to high altitude down to sea-level not only restored growth, but the embryos were actually larger than sea-level embryos incubated at sea-level. The researchers could thereby demonstrate something that only generations of migration in human populations would reveal. What’s more, when looking for early markers of cardiovascular disease, the researchers discovered that growth restriction at high altitude was indeed linked with cardiovascular defects – shown by an increase in the thickness of the walls of the chick heart and aorta. This all suggests the possibility of halting the development of heart disease at its very origin, bringing preventive medicine back into the womb.

Text 2: Questions 15-22

9. What information can be found in the first paragraph?

10. When the writer uses the word ‘cost’ in the second paragraph she is referring to

11. In the third paragraph, what does the author suggest about the work of the international research community on this subject?

12. What was the aim of the study described in the fourth paragraph?

13. What assumption was proved wrong by the results of the study?

14. In the sixth paragraph, what is suggested about the inhabitants of La Paz?

15. The purpose of the information in the sixth paragraph is to provide

16. What advantage of the research involving hen eggs is mentioned in the final paragraph?