问题 单项选择题 A1/A2型题

患者,女性,25岁。饱餐后脐周持续性绞痛伴阵发性加剧3小时。恶心、呕吐数次,解大便1次。查体:体温36.5℃,脉搏每分钟108次,血压80/60mmHg;腹中度膨胀,未见肠型,脐周有明显压痛、反跳痛、肌紧张,肠鸣音消失。腹部X线平片显示腹中部有3个气.液平面,宽度超过5cm,小肠胀气。最可能的诊断为()

A.急性小肠扭转

B.肠伤寒

C.急性胰腺炎

D.急性肠系膜血管栓塞

E.急性肠套叠

答案

参考答案:A

单项选择题
单项选择题

Animal studies are under way, human trial protocols are taking shape and drug makers are on alert. All the international health community needs now is a human vaccine for the bird flu pandemic sweeping a cluster of Asian countries.

The race for a vaccine began after the first human case emerged in Hong Kong in 1997. Backed by the World Health Organization (WHO), three research teams in the US and UK are trying to create a seed virus for a new vaccine. Their task is formidable, but researchers remain optimistic." There are obstacles, but most of the obstacles have been treated sensibly," says Richard Webby, a virologist at St. Jude Children’s Research Hospital in Memphis, Tennessee.

The biggest challenge is likely to be the rapidly mutating virus. Candidate vaccines produced last year against the H5N1 virus are ineffective against this year’s strain. Scientists will have to constantly monitor the changes and try to tailor the vaccine as the virus mutates. They can’t wait to see which one comes next.

The urgency stems from fears that I-ISN1 will combine with a human flu virus, creating a pathogen(病原体) that could be transmitted from person to person. But if people have no immunity to the virus, the strain may not mutate as rapidly in people as it does in birds.

To quickly generate the vaccine, researchers are using reverse genetics, which allows them to skip the long process of searching through reassorted viruses for the correct genetic combination. Instead, scientists clone sequences for hemagglutinin(红血球凝聚素) and neuraminidase(神经氨酸苷酶), the two key proteins in the virus. The sequences are then combined with human influenza genes to create a customized reference strain.

Because products developed with reverse genetics have never been tested in humans, the candidate vaccines will first have to clear regulatory review. In anticipation, the US Food and Drug Administration (FDA) and the European Agency for the Evaluation of Medicinal Products (EMEA) are both preparing pandemic response plans. The EMEA has produced a fist-track licensing program, an industry task force and detailed guidance for potential applicants.

In Europe, a reassortant influenza virus -- but not the inactivated vaccine -- produced by reverse genetics would be considered a genetically modified organism, and manufacturers would need approval from their national or local safety authorities. The WHO has prepared a preliminary biosafety risk assessment of pilot-lot vaccine, which could help speed up the review.

A preliminary version of their protocol calls for several hundred subjects, beginning with a group of young adults and gradually expanding to include those most susceptible to the flu -- children and the elderly." If we had product," says Lambert," it would probably be a couple of months at the earliest before we have early data in healthy adults.

We can infer from Paragraph 2 that facing the tough task the researchers of WHO ()

A. flinch from their work

B. hesitate and feel perplexed

C. carry on their research

D. abandon their research