阅读理解
阅读理解
On Antibodies Substances foreign to the body, such as disease-causing bacteria and viruses and other infectious agents, are recognized by the body s immune system as invaders. Our natural defenses against these infectious agents are antibodies, proteins that seek out the antigens (抗原) and help destroy them. Antibodies have two very useful characteristics. First, they are extremely specific; that is, each antibody binds to and attacks one particular antigen. Second, some antibodies, once activated by the occurrence of a disease, continue to confer resistance against that disease. Classic example are the antibodies to the childhood diseases of chickenpox(水痘) and measles. The second characteristic of antibodies makes it possible to develop vaccines. A vaccine (痘苗) is a preparation of killed or weakened bacteria or viruses that, when introduced into the body, stimulates the production of antibodies against the antigens it contains. It is the first trait of antibodies, their specificity, that makes monoclonal antibody technology so valuable. Not only can antibodies be used therapeutically(在治疗上), to protect against disease; they can also help to .diagnose a wide variety of illnesses, and can detect the presence of drugs, viral and bacterial products, and other unusual or abnormal substances in the blood. Given such a diversity of uses for these diseased-fighting substances, their production in pure quantities has long been the focus of scientific investigation. The conventional method was to inject a laboratory animal with an antigen and then, after antibodies had been formed, collect those antibodies from the blood serum(血清) (Antibody containing blood serum is called antiserum (抗血清)). There are two problems with this method: It yields antiserum that contains undesired substances, and it provides a very small amount of usable antibody. Monoclonal antibody technology allows us to produce large amounts of pure antibodies. in the following way: we can obtain cells that produce antibodies naturally; we also have available a class of cells that can grow continually in cell culture (培养). If we form a hybrid (混血儿) that combines the characteristic of "immortality"(永生)with the ability to produce the desired substance, we would have, in effect, a factory to produce antibodies that work around the clock. In monoclonal antibody technology, tumor cells that can replicate (重复) endlessly are fused with mammalian cells that produce an antibody. The result of this cell fusion is a "hybridoma" (杂交瘤), which will continually produce antibodies. These antibodies are called monoclonal because they come from only one type of cell, the hybridoma cell; antibodies produced by conventional methods, on the other hand, are derived from preparations containing many kinds of cells, and hence are called polyclonal. An example of how monoclonal antibodies are derived is described below. A myeloma is a tumor of the bone marrow (骨髓) that can be adapted to grow permanendy in cell culture. When myeloma cells were fused with antibody-producing mammalian spleen cells, it was found that the resulting hybrid cells, or hybridomas, produced large amounts of monoclonal(骨髓瘤) antibody. This product of cell fusion combined the desired qualities of the two different types of cells: the ability to grow continually, and the ability to produce large amounts of pure antibody. Because selected hybrid cells produce only one specific antibody, they are more pure than the polyclonal antibodies produced by conventional techniques. They are potentially more effective than conventional drugs in fighting disease, since drugs attack not only the foreign substance but the body’s own cells as well, sometimes producing undesirable side effects such as nausea(恶心) and allergic reactions. Monoclonal antibodies attack the target molecule and only the target molecule, with no or greatly diminished side effects. The polyclonal antibodies are different from the monoclonal ones in all the following ways except that______.
A:the productive techniques are different B:the former contains some undesired substances C:the former attacks the foreign substance D:the former produces side effects, that is, attack the body’s own cells
On Antibodies Substances foreign to the body, such as disease-causing bacteria and viruses and other infectious agents, are recognized by the body s immune system as invaders. Our natural defenses against these infectious agents are antibodies, proteins that seek out the antigens (抗原) and help destroy them. Antibodies have two very useful characteristics. First, they are extremely specific; that is, each antibody binds to and attacks one particular antigen. Second, some antibodies, once activated by the occurrence of a disease, continue to confer resistance against that disease. Classic example are the antibodies to the childhood diseases of chickenpox(水痘) and measles. The second characteristic of antibodies makes it possible to develop vaccines. A vaccine (痘苗) is a preparation of killed or weakened bacteria or viruses that, when introduced into the body, stimulates the production of antibodies against the antigens it contains. It is the first trait of antibodies, their specificity, that makes monoclonal antibody technology so valuable. Not only can antibodies be used therapeutically(在治疗上), to protect against disease; they can also help to .diagnose a wide variety of illnesses, and can detect the presence of drugs, viral and bacterial products, and other unusual or abnormal substances in the blood. Given such a diversity of uses for these diseased-fighting substances, their production in pure quantities has long been the focus of scientific investigation. The conventional method was to inject a laboratory animal with an antigen and then, after antibodies had been formed, collect those antibodies from the blood serum(血清) (Antibody containing blood serum is called antiserum (抗血清)). There are two problems with this method: It yields antiserum that contains undesired substances, and it provides a very small amount of usable antibody. Monoclonal antibody technology allows us to produce large amounts of pure antibodies. in the following way: we can obtain cells that produce antibodies naturally; we also have available a class of cells that can grow continually in cell culture (培养). If we form a hybrid (混血儿) that combines the characteristic of "immortality"(永生)with the ability to produce the desired substance, we would have, in effect, a factory to produce antibodies that work around the clock. In monoclonal antibody technology, tumor cells that can replicate (重复) endlessly are fused with mammalian cells that produce an antibody. The result of this cell fusion is a "hybridoma" (杂交瘤), which will continually produce antibodies. These antibodies are called monoclonal because they come from only one type of cell, the hybridoma cell; antibodies produced by conventional methods, on the other hand, are derived from preparations containing many kinds of cells, and hence are called polyclonal. An example of how monoclonal antibodies are derived is described below. A myeloma is a tumor of the bone marrow (骨髓) that can be adapted to grow permanendy in cell culture. When myeloma cells were fused with antibody-producing mammalian spleen cells, it was found that the resulting hybrid cells, or hybridomas, produced large amounts of monoclonal(骨髓瘤) antibody. This product of cell fusion combined the desired qualities of the two different types of cells: the ability to grow continually, and the ability to produce large amounts of pure antibody. Because selected hybrid cells produce only one specific antibody, they are more pure than the polyclonal antibodies produced by conventional techniques. They are potentially more effective than conventional drugs in fighting disease, since drugs attack not only the foreign substance but the body’s own cells as well, sometimes producing undesirable side effects such as nausea(恶心) and allergic reactions. Monoclonal antibodies attack the target molecule and only the target molecule, with no or greatly diminished side effects. Which of the following substances is not an invader to the body’s immune system?
A:disease-causing bacteria B:disease-causing viruses C:antigens D:protein
| ? ? Antibiotic resistance doesn’t just
make pathogens(病原体) difficult to treat, It also makes them harder to track
Traditionally, epidemiologists(流行病专家)following the paths of disease-causing
microbes have identified their suspects by features of bacterial
polysaccharide(多糖) coats, susceptibility to different antibiotics, or other
schemes But these tracking techniques "are losing their relevance (相关性,实用性),
"says Alexander Tomasz, a microbiologist at Rockefeller University in New York
City. With the increase in drug resistance, a variety of resistant microbes can
now wear the same coat or be resistant to the same drugs, making it harder and
harder to keep tabs on individual strains (菌株). ? ? Epidemiologists, therefore, are increasingly turning to more precise molecular typing techniques, such as DNA fingerprinting, to distinguish resistant strains. ? ? DNA typing tools are, of course, not new. Indeed, some DNA-based methods, such as comparing plasmids (质体)(small rings of DNA outside the chromosomes 〈染色体〉), have been used by epidemiologists to track infections since the 1970s. but since plasmid DNA is transferred easily and often between different strains, that technique too has its limitations. ? ? ?More recent techniques use restriction enzymes to cut apart entire bacterial chromosomes into strain-specific fragment patterns, Another method uses specific radiolabeled (放射标汇的) DNA probes, in a technique known as Southern hybridization(杂交), to test for the presence of a particular drug-resistance gene in a bacterial strain. "Such tools give epidemiologists, unprecedented resolving power for identifying reservoirs and transition routes of genes and pathogens, "says Tomasz. That has helped researchers track a number of drug-resistant clones as they travel vast distances. ? ? ?Such tracking methods also "help us learn about the mechanism of resistance, "says CDC(疾病控制和预防中心) epidemiologist Robert Breiman. Resistance grows, he explains, either as one resistant organism spreads from one location to the next—as in the Brazilian MRSA(耐甲氧苯青素金黄色葡萄球菌)—or as different strains and even species of microbes share the genes responsible for drug resistance, as a series of studies of vancomycin(万古霉素) resistance recently demonstrated. ? ? That knowledge also helps public health officials combat the spread. If resistance spreads "horizontally’as a microbe increases its range, Breiman says it’s important to focus prevention efforts on minimizing person-to-person spread in hospitals and day-care centers. If, however, resistance genes are jumping between organisms, that suggests that overly aggressive antibiotic treatment is encouraging nonresistant bugs to acquire new genes. "In such cases, the focus needs to be on controlling anti-microbial use, "says Breiman. The hoped-for result: fewer infections to track. |
A:A．
B:B．
Right ? ? ? ? ? ? ? ? ? ?
C:C．
Wrong ? ? ? ? ? ? ? ? ?
Not mentioned
| ? ? Antibiotic resistance doesn’t just
make pathogens(病原体) difficult to treat, It also makes them harder to track
Traditionally, epidemiologists(流行病专家)following the paths of disease-causing
microbes have identified their suspects by features of bacterial
polysaccharide(多糖) coats, susceptibility to different antibiotics, or other
schemes But these tracking techniques "are losing their relevance (相关性,实用性),
"says Alexander Tomasz, a microbiologist at Rockefeller University in New York
City. With the increase in drug resistance, a variety of resistant microbes can
now wear the same coat or be resistant to the same drugs, making it harder and
harder to keep tabs on individual strains (菌株). ? ? Epidemiologists, therefore, are increasingly turning to more precise molecular typing techniques, such as DNA fingerprinting, to distinguish resistant strains. ? ? DNA typing tools are, of course, not new. Indeed, some DNA-based methods, such as comparing plasmids (质体)(small rings of DNA outside the chromosomes 〈染色体〉), have been used by epidemiologists to track infections since the 1970s. but since plasmid DNA is transferred easily and often between different strains, that technique too has its limitations. ? ? ?More recent techniques use restriction enzymes to cut apart entire bacterial chromosomes into strain-specific fragment patterns, Another method uses specific radiolabeled (放射标汇的) DNA probes, in a technique known as Southern hybridization(杂交), to test for the presence of a particular drug-resistance gene in a bacterial strain. "Such tools give epidemiologists, unprecedented resolving power for identifying reservoirs and transition routes of genes and pathogens, "says Tomasz. That has helped researchers track a number of drug-resistant clones as they travel vast distances. ? ? ?Such tracking methods also "help us learn about the mechanism of resistance, "says CDC(疾病控制和预防中心) epidemiologist Robert Breiman. Resistance grows, he explains, either as one resistant organism spreads from one location to the next—as in the Brazilian MRSA(耐甲氧苯青素金黄色葡萄球菌)—or as different strains and even species of microbes share the genes responsible for drug resistance, as a series of studies of vancomycin(万古霉素) resistance recently demonstrated. ? ? That knowledge also helps public health officials combat the spread. If resistance spreads "horizontally’as a microbe increases its range, Breiman says it’s important to focus prevention efforts on minimizing person-to-person spread in hospitals and day-care centers. If, however, resistance genes are jumping between organisms, that suggests that overly aggressive antibiotic treatment is encouraging nonresistant bugs to acquire new genes. "In such cases, the focus needs to be on controlling anti-microbial use, "says Breiman. The hoped-for result: fewer infections to track. |
A:A．
B:B．
Right ? ? ? ? ? ? ? ? ? ?
C:C．
Wrong ? ? ? ? ? ? ? ? ?
Not mentioned
| ? ? Antibiotic resistance doesn’t just
make pathogens(病原体) difficult to treat, It also makes them harder to track
Traditionally, epidemiologists(流行病专家)following the paths of disease-causing
microbes have identified their suspects by features of bacterial
polysaccharide(多糖) coats, susceptibility to different antibiotics, or other
schemes But these tracking techniques "are losing their relevance (相关性,实用性),
"says Alexander Tomasz, a microbiologist at Rockefeller University in New York
City. With the increase in drug resistance, a variety of resistant microbes can
now wear the same coat or be resistant to the same drugs, making it harder and
harder to keep tabs on individual strains (菌株). ? ? Epidemiologists, therefore, are increasingly turning to more precise molecular typing techniques, such as DNA fingerprinting, to distinguish resistant strains. ? ? DNA typing tools are, of course, not new. Indeed, some DNA-based methods, such as comparing plasmids (质体)(small rings of DNA outside the chromosomes 〈染色体〉), have been used by epidemiologists to track infections since the 1970s. but since plasmid DNA is transferred easily and often between different strains, that technique too has its limitations. ? ? ?More recent techniques use restriction enzymes to cut apart entire bacterial chromosomes into strain-specific fragment patterns, Another method uses specific radiolabeled (放射标汇的) DNA probes, in a technique known as Southern hybridization(杂交), to test for the presence of a particular drug-resistance gene in a bacterial strain. "Such tools give epidemiologists, unprecedented resolving power for identifying reservoirs and transition routes of genes and pathogens, "says Tomasz. That has helped researchers track a number of drug-resistant clones as they travel vast distances. ? ? ?Such tracking methods also "help us learn about the mechanism of resistance, "says CDC(疾病控制和预防中心) epidemiologist Robert Breiman. Resistance grows, he explains, either as one resistant organism spreads from one location to the next—as in the Brazilian MRSA(耐甲氧苯青素金黄色葡萄球菌)—or as different strains and even species of microbes share the genes responsible for drug resistance, as a series of studies of vancomycin(万古霉素) resistance recently demonstrated. ? ? That knowledge also helps public health officials combat the spread. If resistance spreads "horizontally’as a microbe increases its range, Breiman says it’s important to focus prevention efforts on minimizing person-to-person spread in hospitals and day-care centers. If, however, resistance genes are jumping between organisms, that suggests that overly aggressive antibiotic treatment is encouraging nonresistant bugs to acquire new genes. "In such cases, the focus needs to be on controlling anti-microbial use, "says Breiman. The hoped-for result: fewer infections to track. |
A:A．
B:B．
Right ? ? ? ? ? ? ? ? ? ?
C:C．
Wrong ? ? ? ? ? ? ? ? ?
Not mentioned
| ? ? Antibiotic resistance doesn’t just
make pathogens(病原体) difficult to treat, It also makes them harder to track
Traditionally, epidemiologists(流行病专家)following the paths of disease-causing
microbes have identified their suspects by features of bacterial
polysaccharide(多糖) coats, susceptibility to different antibiotics, or other
schemes But these tracking techniques "are losing their relevance (相关性,实用性),
"says Alexander Tomasz, a microbiologist at Rockefeller University in New York
City. With the increase in drug resistance, a variety of resistant microbes can
now wear the same coat or be resistant to the same drugs, making it harder and
harder to keep tabs on individual strains (菌株). ? ? Epidemiologists, therefore, are increasingly turning to more precise molecular typing techniques, such as DNA fingerprinting, to distinguish resistant strains. ? ? DNA typing tools are, of course, not new. Indeed, some DNA-based methods, such as comparing plasmids (质体)(small rings of DNA outside the chromosomes 〈染色体〉), have been used by epidemiologists to track infections since the 1970s. but since plasmid DNA is transferred easily and often between different strains, that technique too has its limitations. ? ? ?More recent techniques use restriction enzymes to cut apart entire bacterial chromosomes into strain-specific fragment patterns, Another method uses specific radiolabeled (放射标汇的) DNA probes, in a technique known as Southern hybridization(杂交), to test for the presence of a particular drug-resistance gene in a bacterial strain. "Such tools give epidemiologists, unprecedented resolving power for identifying reservoirs and transition routes of genes and pathogens, "says Tomasz. That has helped researchers track a number of drug-resistant clones as they travel vast distances. ? ? ?Such tracking methods also "help us learn about the mechanism of resistance, "says CDC(疾病控制和预防中心) epidemiologist Robert Breiman. Resistance grows, he explains, either as one resistant organism spreads from one location to the next—as in the Brazilian MRSA(耐甲氧苯青素金黄色葡萄球菌)—or as different strains and even species of microbes share the genes responsible for drug resistance, as a series of studies of vancomycin(万古霉素) resistance recently demonstrated. ? ? That knowledge also helps public health officials combat the spread. If resistance spreads "horizontally’as a microbe increases its range, Breiman says it’s important to focus prevention efforts on minimizing person-to-person spread in hospitals and day-care centers. If, however, resistance genes are jumping between organisms, that suggests that overly aggressive antibiotic treatment is encouraging nonresistant bugs to acquire new genes. "In such cases, the focus needs to be on controlling anti-microbial use, "says Breiman. The hoped-for result: fewer infections to track. |
A:A．
B:B．
Right ? ? ? ? ? ? ? ? ? ?
C:C．
Wrong ? ? ? ? ? ? ? ? ?
Not mentioned
| ? ? Antibiotic resistance doesn’t just
make pathogens(病原体) difficult to treat, It also makes them harder to track
Traditionally, epidemiologists(流行病专家)following the paths of disease-causing
microbes have identified their suspects by features of bacterial
polysaccharide(多糖) coats, susceptibility to different antibiotics, or other
schemes But these tracking techniques "are losing their relevance (相关性,实用性),
"says Alexander Tomasz, a microbiologist at Rockefeller University in New York
City. With the increase in drug resistance, a variety of resistant microbes can
now wear the same coat or be resistant to the same drugs, making it harder and
harder to keep tabs on individual strains (菌株). ? ? Epidemiologists, therefore, are increasingly turning to more precise molecular typing techniques, such as DNA fingerprinting, to distinguish resistant strains. ? ? DNA typing tools are, of course, not new. Indeed, some DNA-based methods, such as comparing plasmids (质体)(small rings of DNA outside the chromosomes 〈染色体〉), have been used by epidemiologists to track infections since the 1970s. but since plasmid DNA is transferred easily and often between different strains, that technique too has its limitations. ? ? ?More recent techniques use restriction enzymes to cut apart entire bacterial chromosomes into strain-specific fragment patterns, Another method uses specific radiolabeled (放射标汇的) DNA probes, in a technique known as Southern hybridization(杂交), to test for the presence of a particular drug-resistance gene in a bacterial strain. "Such tools give epidemiologists, unprecedented resolving power for identifying reservoirs and transition routes of genes and pathogens, "says Tomasz. That has helped researchers track a number of drug-resistant clones as they travel vast distances. ? ? ?Such tracking methods also "help us learn about the mechanism of resistance, "says CDC(疾病控制和预防中心) epidemiologist Robert Breiman. Resistance grows, he explains, either as one resistant organism spreads from one location to the next—as in the Brazilian MRSA(耐甲氧苯青素金黄色葡萄球菌)—or as different strains and even species of microbes share the genes responsible for drug resistance, as a series of studies of vancomycin(万古霉素) resistance recently demonstrated. ? ? That knowledge also helps public health officials combat the spread. If resistance spreads "horizontally’as a microbe increases its range, Breiman says it’s important to focus prevention efforts on minimizing person-to-person spread in hospitals and day-care centers. If, however, resistance genes are jumping between organisms, that suggests that overly aggressive antibiotic treatment is encouraging nonresistant bugs to acquire new genes. "In such cases, the focus needs to be on controlling anti-microbial use, "says Breiman. The hoped-for result: fewer infections to track. |
A:A．
B:B．
Right ? ? ? ? ? ? ? ? ? ?
C:C．
Wrong ? ? ? ? ? ? ? ? ?
Not mentioned
| ? ? Antibiotic resistance doesn’t just
make pathogens(病原体) difficult to treat, It also makes them harder to track
Traditionally, epidemiologists(流行病专家)following the paths of disease-causing
microbes have identified their suspects by features of bacterial
polysaccharide(多糖) coats, susceptibility to different antibiotics, or other
schemes But these tracking techniques "are losing their relevance (相关性,实用性),
"says Alexander Tomasz, a microbiologist at Rockefeller University in New York
City. With the increase in drug resistance, a variety of resistant microbes can
now wear the same coat or be resistant to the same drugs, making it harder and
harder to keep tabs on individual strains (菌株). ? ? Epidemiologists, therefore, are increasingly turning to more precise molecular typing techniques, such as DNA fingerprinting, to distinguish resistant strains. ? ? DNA typing tools are, of course, not new. Indeed, some DNA-based methods, such as comparing plasmids (质体)(small rings of DNA outside the chromosomes 〈染色体〉), have been used by epidemiologists to track infections since the 1970s. but since plasmid DNA is transferred easily and often between different strains, that technique too has its limitations. ? ? ?More recent techniques use restriction enzymes to cut apart entire bacterial chromosomes into strain-specific fragment patterns, Another method uses specific radiolabeled (放射标汇的) DNA probes, in a technique known as Southern hybridization(杂交), to test for the presence of a particular drug-resistance gene in a bacterial strain. "Such tools give epidemiologists, unprecedented resolving power for identifying reservoirs and transition routes of genes and pathogens, "says Tomasz. That has helped researchers track a number of drug-resistant clones as they travel vast distances. ? ? ?Such tracking methods also "help us learn about the mechanism of resistance, "says CDC(疾病控制和预防中心) epidemiologist Robert Breiman. Resistance grows, he explains, either as one resistant organism spreads from one location to the next—as in the Brazilian MRSA(耐甲氧苯青素金黄色葡萄球菌)—or as different strains and even species of microbes share the genes responsible for drug resistance, as a series of studies of vancomycin(万古霉素) resistance recently demonstrated. ? ? That knowledge also helps public health officials combat the spread. If resistance spreads "horizontally’as a microbe increases its range, Breiman says it’s important to focus prevention efforts on minimizing person-to-person spread in hospitals and day-care centers. If, however, resistance genes are jumping between organisms, that suggests that overly aggressive antibiotic treatment is encouraging nonresistant bugs to acquire new genes. "In such cases, the focus needs to be on controlling anti-microbial use, "says Breiman. The hoped-for result: fewer infections to track. |
A:A．
B:B．
Right ? ? ? ? ? ? ? ? ? ?
C:C．
Wrong ? ? ? ? ? ? ? ? ?
Not mentioned
| ? ? Antibiotic resistance doesn’t just
make pathogens(病原体) difficult to treat, It also makes them harder to track
Traditionally, epidemiologists(流行病专家)following the paths of disease-causing
microbes have identified their suspects by features of bacterial
polysaccharide(多糖) coats, susceptibility to different antibiotics, or other
schemes But these tracking techniques "are losing their relevance (相关性,实用性),
"says Alexander Tomasz, a microbiologist at Rockefeller University in New York
City. With the increase in drug resistance, a variety of resistant microbes can
now wear the same coat or be resistant to the same drugs, making it harder and
harder to keep tabs on individual strains (菌株). ? ? Epidemiologists, therefore, are increasingly turning to more precise molecular typing techniques, such as DNA fingerprinting, to distinguish resistant strains. ? ? DNA typing tools are, of course, not new. Indeed, some DNA-based methods, such as comparing plasmids (质体)(small rings of DNA outside the chromosomes 〈染色体〉), have been used by epidemiologists to track infections since the 1970s. but since plasmid DNA is transferred easily and often between different strains, that technique too has its limitations. ? ? ?More recent techniques use restriction enzymes to cut apart entire bacterial chromosomes into strain-specific fragment patterns, Another method uses specific radiolabeled (放射标汇的) DNA probes, in a technique known as Southern hybridization(杂交), to test for the presence of a particular drug-resistance gene in a bacterial strain. "Such tools give epidemiologists, unprecedented resolving power for identifying reservoirs and transition routes of genes and pathogens, "says Tomasz. That has helped researchers track a number of drug-resistant clones as they travel vast distances. ? ? ?Such tracking methods also "help us learn about the mechanism of resistance, "says CDC(疾病控制和预防中心) epidemiologist Robert Breiman. Resistance grows, he explains, either as one resistant organism spreads from one location to the next—as in the Brazilian MRSA(耐甲氧苯青素金黄色葡萄球菌)—or as different strains and even species of microbes share the genes responsible for drug resistance, as a series of studies of vancomycin(万古霉素) resistance recently demonstrated. ? ? That knowledge also helps public health officials combat the spread. If resistance spreads "horizontally’as a microbe increases its range, Breiman says it’s important to focus prevention efforts on minimizing person-to-person spread in hospitals and day-care centers. If, however, resistance genes are jumping between organisms, that suggests that overly aggressive antibiotic treatment is encouraging nonresistant bugs to acquire new genes. "In such cases, the focus needs to be on controlling anti-microbial use, "says Breiman. The hoped-for result: fewer infections to track. |
A:A．
B:B．
Right ? ? ? ? ? ? ? ? ? ?
C:C．
Wrong ? ? ? ? ? ? ? ? ?
Not mentioned
您可能感兴趣的题目
