Claims negative limitations

Claims are what is said in labeling and advertising, and may be either of a positive (therapeutic or beneficial) or negative (lack of an adverse effect) nature. The positive or efficacy claims are not usually the direct concern of the toxicologist though it must be kept in mind that such claims both must be proved and can easily exceed the limits of the statutory definition of a device, turning the product into a drug or combination product. 

Pearson (1985) supports many of these claims in his study of African American doctoral scientists. Most of his respondents believed that their career mobility had been limited by their racial status. This finding varied across cohorts. For example, 74% of those earning doctorates before 1955 believe their career were restricted by race. By the last cohort, doctorates earned between 1965 and 1974, 60% reported that their career mobility had been restricted. Further, at least half of the females respondents reported that race and gender played significant roles in limited their careers. Some 59% of respondents who earned doctorates at the most prestigious department also reported the negatives effects that race exerted on the careers. Most respondents attributed these limiting factors to discrimination (especially exclusion from the communications network). Many respondents report that open communication between African American and white scientists is impeded by the perception that many white scientists fail to accept African American scientists as intellectual peers. 

Test kit producer-generated data to verify performance claims are required according to an AOAC-approved protocol, to generally include ruggedness tests, calibration curves, accuracy, precision, cross reactivity, test kit component stability, detection limit, limit of quantification and rates of false positives and false negatives. 

A compromise solution for dereplication procedures is to use a combination of ionization modes. In one report (31), electrospray MS in both positive and negative modes was coupled to an HPLC interface and used to obtain information on unknown components of crude biologically active extracts. The authors of this report claimed successful identification of a known natural product in two out of eight biologically active extracts examined, another two compounds were identified as novel, and they assumed that the active components in the remaining four did not ionize or were present at a concentration below the limits of MS detection. 

If not the enzyme, one of its products might exert the regulatory function on DNA replication. The only deoxyribonucleotide without negative feedback action on ribonucleotide reductase, dCTP, has been advanced by Reichard to be involved. Addition of thymidine to hamster cells lowers the dCTP pool and concomitantly inhibits DNA synthesis even when dCTP has not become limiting as substrate . Under these conditions no more initiation of replication takes place and a specific correlation of the two results has been claimed. Conversely, direct inhibition of DNA synthesis by aphidico-... 

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