Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

Q: Abstract: Injection of homologous DNA sequences into nuclei of cultured mammalian cells induces mutations in the cognate chromosomal gene. It appears that these mutations result from incorrect repair of a heteroduplex formed between the introduced and the chromosomal sequence. This phenomenon is termed 'heteroduplex induced mutagenesis'. The high frequency of these events suggests that this method may prove useful for introducing mutations into specific mammalian genes.

A: Introduction of homologous DNA sequences into mammalian cells induces mutations in the cognate gene.
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Q: Abstract: This study evaluated quality of life in 78 patients with closed head injury (CHI) 2 to 4 years postinjury. Using both interview data and mean data from the Sickness Impact Profile questionnaire, impaired quality of life was observed in the areas of psychosocial functioning, social role functioning, leisure activities, and, to a lesser extent, physical functioning, during chronic phases of recovery. Relatives and close friends reported by means of the Katz Adjustment Scale that the CHI patients showed a series of negative behavioral symptoms 2 to 4 years postinjury. These data suggest that CHI patients may experience impaired quality of life in a number of domains well beyond the acute postinjury phases. An attempt was also made to compare patients' and relatives' reports of patient quality of life. Preliminary analyses indicated modest correspondence between relatives' and patients' ratings of some areas of postinjury dysfunction, including cognitive and behavioral slowing and social withdrawal.

A: Quality of life in patients 2 to 4 years after closed head injury.
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Q: Abstract: The measurement of subjective pain intensity continues to be important to both researchers and clinicians. Although several scales are currently used to assess the intensity construct, it remains unclear which of these provides the most precise, replicable, and predictively valid measure. Five criteria for judging intensity scales have been considered in previous research: ease of administration of scoring; relative rates of incorrect responding; sensitivity as defined by the number of available response categories; sensitivity as defined by statistical power; and the magnitude of the relationship between each scale and a linear combination of pain intensity indices. In order to judge commonly used pain intensity measures, 75 chronic pain patients were asked to rate 4 kinds of pain (present, least, most, and average) using 6 scales. The utility and validity of the scales was judged using the criteria listed above. The results indicate that, for the present sample, the scales yield similar results in terms of the number of subjects who respond correctly to them and their predictive validity. However, when considering the remaining 3 criteria, the 101-point numerical rating scale appears to be the most practical index.

A:
The measurement of clinical pain intensity: a comparison of six methods.
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