问题 单项选择题

关于干扰素的特性,错误的是()

A.病毒感染后早期出现

B.抗病毒有种属特异性

C.具有直接杀病毒作用

D.具有广谱抗病毒作用

E.属于非特异性免疫因素

答案

参考答案:C

解析:干扰素不具有直接杀灭病毒的作用,而是通过诱导细胞合成抗病毒蛋白(AVP)发挥效应。干扰素的作用特点:①间接性:通过诱导细胞产生抗病毒蛋白等效应分子抑制病毒。②广谱性:抗病毒蛋白是一类酶类,作用无特异性。对多数病毒均有一定抑制作用。属非特异性免疫。③种属特异性:一般在同种细胞中活性高,对异种细胞无活性。④发挥作用迅速:在感染的起始阶段体液免疫和细胞免疫发生作用之前,干扰素发挥重要作用。

判断题
单项选择题

Feeling anxious Your mood may actually change how your dinner tastes, making the bitter and salty flavors recede, according to new research. This link between the chemical balance in your brain and your sense of taste could one day help doctors to treat depression. There are currently no on-the-spot tests for deciding which medication will work best in individual patients with this condition. Researchers hope that a test based on flavor detection could help doctors to get more prescriptions right first time.

It has long been known that people who are depressed have lower-than-usual levels of the brain chemicals serotonin or noradrenaline, or in some cases both. Many also have a blunted sense of taste, which is presumably caused by changes in brain chemistry. To unpick the relationship between the two, Lucy Donaldson and her colleagues at the University of Bristol, UK, gave 20 healthy volunteers two antidepressant drugs, and checked their sensitivity to different tastes. The drug that raised serotonin levels made people more sensitive to sweet and bitter tastes, the team reports in the Journal of Neuroscience. The other, which increased noradrenaline, enhanced recognition of bitter and sour tastes.

In healthy people, volunteers whose anxiety levels were naturally higher were less sensitive to bitter and salty tastes. "What hasn’t been done beore is to look precisely at which tastes are affected in depression," says Donaldson. Now the results are in, "we can discriminate between the chemicals and the tastes that seem to be altered," she says. Testing sensitivity to sweet and sour tastes could potentially help doctors to pick up on which chemicals are dipping, guiding them when choosing which drug to rectify the problem.

Currently, doctors rely on physical and emotional symptoms to make a best guess at an individual’s imbalance, prescribe a drug and wait about a month to check on any improvement. Good doctors have about a 60-80% success rate in selecting the right drug the first time, says psychiatrist Jan Melichar, a co-author on the paper. Are there any decent tests for prescribing drugs for depression "No. We do a best guesstimate," says Melichar. "I’m excited by this finding because in 3, 5 or 7 years we could have a simple taste test. "

Next, the team plans to perform similar tests in depressed people, and in healthy volunteers given another brain chemical called tryptophan. This chemical would lower the healthy subjects’ levels of serotonin, as actually happens in depressed patients.

The work has also generated interest from flavor houses--companies that develop chemicals for the food and drink industry--who are interested in making foods taste just as sweet with half the amount of sugar. "Theoretically there would be the possibility of enhancing your meal with drugs that affect brain chemicals so that things would taste better--you couid have a ’designer taste tablet’," Donaldson says.

Which of the following is TRUE as to the results of the research()

A. Increased serotonin weakens sensitivity to the tastes of bitter and sour

B. The more anxious people are, the more sensitive to sour taste

C. The tryptophan can add healthy people’s serotonin amount

D. The tryptophan can lower healthy people’s serotonin level