Re: Biomedical Research/carbon 14

[BLHamrick@AOL.COM]

In a message dated 03/23/2002 10:28:48 PM Pacific Standard Time, bcradsafers@HOTMAIL.COM writes:



> I think that the amounts or concentrations of C-14 may vary much (orders of 
>
> magnitudes) depending on the contexts (How many cells will be used? How many 
>
> molecules can be expected to be radiolabeled?). Many pulsed field gel 
>
> electrophoresis, PFGE (labeling of DNA) have included C-14 labeled DNA - 
>
> typically to label 200 000 cells or more per sample that is analyzed. Lots 
>
> of old molecular genetics experiments (phages, bacteria stuff from the 
>
> 1950-60:ies) included C-14. The cell cycle has often been followed with C-14 
>
> thymidine for the labeling of  DNA in the replication/duplication phase).
>
>
> For DNA labeling (PFGE) the order of 0.3 - 1.0 kBq per of medium may be the 
>
> approx. amount.
>
>
> Many others can probably give more precise and direct examples.


Thanks.  To clarify, all I'm really looking for is something that is realistic to use in an example of why no one uses an "above background with the best available technology" to "release" items from a restricted area on a routine basis.  I.e., what activity might typically be used in a research lab in one day?  Would it be reasonable to withdraw 100 microcuries from a stock vial to use at one's workstation in a labeling procedure?  Although I've inspected hundreds of laboratories over the years, I haven't really paid attention to the protocols, because that's not our focus.


Barbara