Myoblasts appear to be good candidates for use in gene therapy because

Question

New Project RC Butler 2019  -  Practice 2 RC Passages Everyday   
Passage # 381, Date : 10-Oct-2019
 This post is a part of New Project RC Butler 2019 .  Click here for Details

Myoblasts appear to be good candidates for use in gene therapy because of an unusual and advantageous biological property: when injected into muscle, they fuse with nearby muscle fibers and become an integral part of the muscle tissue. Moreover, since muscle tissue is generally well supplied with nerves and blood, the therapeutic agents produced by the transgene are also accessible to nerves and the circulatory system. Thus, myoblasts may not only be useful for treating muscle disorders such as muscular dystrophy, but also nonmuscle disorders such as neurodegenerative diseases and inherited hormone deficiencies.

In a series of experiments in rodents, a team of investigators has been testing neural stem cells as vehicles for cell-based gene therapy for brain tumors known as gliomas. Gliomas are virtually impossible to treat because the tumor cells readily invade the surrounding tissue and migrate extensively into the normal brain. The researchers genetically modified human neural stem cells to produce a protein, cytosine deaminase, that converts a nontoxic precursor drug into an active form that kills cancer cells. The engineered neural stem cells were then injected into the brains of mice with human-derived gliomas. Within two weeks of the gene therapy and systemic treatment with the precursor drug, the tumors had shrunk by 80 percent. The animal studies also revealed that neural stem cells were able to quickly and accurately "find" glioma cells, regardless of whether the stem cells were implanted directly into the tumors, implanted far from the tumors (but still within the brain), or injected into circulating blood outside the brain.

Another cell-based gene therapy system under investigation involves the use of osteoblasts. In a recent preliminary study examining a gene therapy approach to bone repair and regeneration, researchers genetically engineered osteoblasts to produce a bone growth factor. The osteoblasts were added to a biodegradable matrix that could act as a "scaffold" for new bone formation. Within a month after the cell-impregnated scaffold was implanted into mice, new bone formation was detectable. Although this work is in the very early stages, it offers hope of an effective alternative to conventional bone-grafting techniques.   1 
 E 
 1. Why does the author mention that muscle tissue is generally well supplied with nerves and blood in the second sentence of the first paragraph?

(A) to offer further proof that the advantageous biological properties of myoblasts distinguish them from osteoblasts
(B) to elaborate upon the hypothesis that myoblasts can be used to treat coronary heart disease
(C) to describe how myoblasts are able to deliver therapeutic agents for the treatment of muscular dystrophy
(D) to provide evidence that myoblasts are truly integrated into the actual fibers of a recipient muscle
(E) to explain how a transgene that binds to muscle fibers can affect — other bodily systems

2 
 B 
 2. The author of this passage would most likely agree with which of the following statements?

(A) Most cell-based gene therapy systems have only been proven to work on mice and are years away from human trials.
(B) Recent research indicates that cell-based gene therapy may provide new methods of treating multiple disorders and diseases in humans.
(C) There are no gene therapy treatment methods that have been shown to be truly effective in combating gliomas.
(D) Osteoblasts, as indicated by their name, are used exclusively in the treatment of bone injuries and disorders.
(E) Nontoxic precursor drugs generally do not cause significant side effects in recipients.

3 
 D 
 3. The author suggests that neural stem cells exhibit which of the following traits?

I.  the ability to consume gliomas
 II.  the ability to distribute themselves via the circulatory system
 III.  the ability to treat brain tumors

(A) I ONLY
(B) II ONLY
(C) I and II ONLY
(D) II and III ONLY
(E)I, II and III

4 
 D 
 4. The content of the passage leads most naturally to which of the following conclusions?

(A) Myoblast ‘scaffolding’ offers hope to patients currently facing painful bone-grafting operations.
(B) While neural stem cell research may appear promising, ethical debate surrounding it will likely hamper future applications of this new system
(C) Cytosine deaminase effectively reduces brain tumors formed by gliomas.
(D) Researchers are studying several methods of delivering cell-based gene therapy.
(E) Myoblasts offer the most promising mechanism for cell-based gene therapy.

QUESTION- 1

The author mentions that muscle tissue is generally well supplied with nerves and blood to explain how the myoblasts, which bind to muscle fiber, can deliver therapeutic agents to other parts of the body. Since the muscles are well connected to other bodily systems, myoblasts are able to treat "nonmuscle disorders such as neurodegenerative diseases and inherited hormone deficiencies" as stated in the final sentence of paragraph one.

QUESTION- 2

While choices A, D, and E could be true, they fall outside the scope of the passage. Choice C is countered by evidence presented in the passage. Choice B summarizes the main idea of the passage. Thus, choice B is the best choice.

QUESTION- 3

The passage does not state that neural stem cells consume gliomas but rather that they can be modified to produce a protein that converts a precusor drug that in turn kills gliomas. Choice A, C, and E can be eliminated.
In the last sentence of the second paragraph, the passage states that neural stem cells can "find" gliomas in the brain even when injected into blood outside the brain. Thus, neural stem cells must have the ability to distribute via the circulatory system. Also, the first sentence of the second paragraph states that gliomas are brain tumors. Since neural stem cells can be used to treat gliomas, they are being used to treat brain tumors. Choice D is correct.

QUESTION- 4

The passage discusses three different vehicles for cell-based gene therapy. Thus, choice D is correct.

Hoozan · Answer

SajjadAhmad

1 - E
2 - E
3 - D
4 - D

Please could I get an answer explanation for Q2. & Q3.

Sajjad1994 · Answer

Official Explanation

2. The author of this passage would most likely agree with which of the following statements?

Difficulty Level:   600

Explanation

While  choices A, D, and E  could be true, they fall outside the scope of the passage.  Choice C  is countered by evidence presented in the passage.  Choice B  summarizes the main idea of the passage. Thus,  choice B  is the best choice.

Answer: B

3. The author suggests that neural stem cells exhibit which of the following traits?

Difficulty Level:   700

Explanation

The passage does not state that neural stem cells consume gliomas but rather that they can be modified to produce a protein that converts a precusor drug that in turn kills gliomas. Choice  A, C, and E  can be eliminated.

In the last sentence of the  second paragraph , the passage states that neural stem cells can  "find"  gliomas in the brain even when injected into blood outside the brain. Thus, neural stem cells must have the ability to distribute via the circulatory system.

Also, the first sentence of the  second paragraph  states that gliomas are brain tumors. Since neural stem cells can be used to treat gliomas, they are being used to treat brain tumors.

Answer: D

abhishektyga · Answer

Please provide explanation for Q1 and Q4. 
Why option D in Q4 instead of E and why option E instead of c in Q1?

summerindecember · Answer

hi  Sajjad1994

can you please explain why Q1 is E?

Sajjad1994 · Answer

Official Explanation

1. Why does the author mention that muscle tissue is generally well supplied with nerves and blood in the second sentence of the first paragraph?

Difficulty Level:   650-700

Explanation

The author mentions that muscle tissue is generally well supplied with nerves and blood to explain how the myoblasts, which bind to muscle fiber, can deliver therapeutic agents to other parts of the body. Since the muscles are well connected to other bodily systems, myoblasts are able to treat "nonmuscle disorders such as neurodegenerative diseases and inherited hormone deficiencies" as stated in the final sentence of paragraph one.

Answer: E

Sajjad1994 · Answer

Official Explanation

4. The content of the passage leads most naturally to which of the following conclusions?

Difficulty Level:   550-600

Explanation

The passage discusses three different vehicles for cell-based gene therapy. Thus, choice D is correct.

Answer: D

mkeshri185 · Answer

There are no gene therapy treatment methods that have been shown to be truly effective in combating gliomas.

this is what option C is saying in Q2. This option is talking about 'tiil present' situation. But those experiments are done on mice we can't say they are fully prepared to be used to remove gliomas. then how is this wrong?

Priyank1905 · Answer

For  question 3 III , If we look at the passage, it says that gliomas had shrunk by 80%, So how can we consider this that neural stem cells are able to cure it. The passage is just mentioning about its shrinking rather than getting cured.

Please help me and explain

Sajjad1994 · Answer

Hello mkeshri185

The passage describes  three different cell-based gene therapy approaches  using different cell types (myoblasts, neural stem cells, and osteoblasts) for different medical problems (muscle/nonmuscle disorders, brain tumors, bone repair). The author's tone is optimistic about the potential of these methods, based on animal studies.

A.  The passage doesn’t generalize about  “most”  systems, and it doesn’t focus on the timeline to human trials; it emphasizes promise, not delay. This is too negative.

B.  This is correct, this matches the passage’s overall message: multiple examples, multiple diseases, potential for new treatments.

C.  This is contradicted by the rodent experiment showing 80% tumor shrinkage. This is out. The passage says  "Within two weeks of the gene therapy and systemic treatment with the precursor drug, the tumors had shrunk by 80 percent."  Hence C is incorrect.

D. “Exclusively”  here is too strong; the passage doesn’t say they can’t be used for other things in the future.

E  is not discussed even, the passage only says the drug is nontoxic in its precursor form, not that it has no side effects after conversion.

Answer: B

Sajjad1994 · Answer

Hello Priyank1905

The passage says the tumors shrunk by 80%, not that they were cured. What the question actually asked is neural stem cells exhibit which of the following traits?

III says:  “the ability to treat brain tumors.”   “treat”  doesn’t necessarily mean  “cure.”  If a therapy causes significant tumor shrinkage, that is a form of treatment (even if not a complete cure). The passage clearly presents this as a gene therapy for brain tumors using neural stem cells, and the result (80% shrinkage) demonstrates a treatment effect. So according of the passage, the author does suggest neural stem cells have the ability to treat brain tumors.

bestreturn · Answer

I dont really agree with Q3

The author suggests that neural stem cells exhibit which of the following traits?
III. the ability to treat brain tumors

The neural stem cells itself does not have the ability to treat brain tumors, but if the question states "engineered neural stem cells" it would have made III true.

miag · Answer

Hi, 
In order to clarify this, I would like to highlight a few parts of the passage: 
 
 The investigators are "testing neural stem cells as vehicles for cell-based gene therapy for brain tumors." - This already gives us a hint that the underlying idea of this paragraph is to ascertain ability of stem cells to help treat brain tumors (gliomas) 
 Later, the passage states that after injecting the neural stem cells, the tumors shrank. While this may have been engineered stem cells they are stem cells nonetheless and they helped shrink the tumors which paraphrasing means they helped treat brain tumors  
  "Neural stem cells were able to quickly and accurately "find" glioma cells...   
>> These points taken together already make III. correct. It is this property of being able to find the glioma cells that => ability to treat the brain tumors

Hope this helps!

Myoblasts appear to be good candidates for use in gene therapy because

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Reading Comprehension (RC) Questions

Myoblasts appear to be good candidates for use in gene therapy because

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards