Re: Dr. Raabe's Work

["Otto G. Raabe" <ograabe@ucdavis.edu>]

The Reference for the article from Reuters is:

Wiley, L.M., Baulch, J.D., Raabe, O.G., and Straume, T. "Impaired cell
proliferation in mice that persists across at least two generations from
paternal irradiation," Radiation Research 148: 145-151 (1997)

At 04:43 PM 11/10/97 -0600, you wrote:
>Interesting.....
>
>Radiation Effects May Be
>                    Inherited 
>
>                    November 10, 1997
>
>                    NEW YORK (Reuters) - Defects in cell reproduction
>and growth resulting
>                    from exposure to radiation may be passed along to
>future generations,
>                    according to a study in laboratory mice. 
>
>                    The defects occurred in about 20% of the children
>and grandchildren of male
>                    mice whose gonads were exposed to extremely high
>radiation levels prior to
>                    mating. 
>
>                    Scientists at the University of California-Davis, in
>Davis, California, observed
>                    the defects in embryos, called "chimera," which were
>created when embryo
>                    cells taken from the female mates of irradiated mice
>were combined with
>                    embryo cells taken from mice that had not been
>exposed to radiation. 
>
>                    "We allowed that (chimera) to go through two or
>three cycles of cell division
>                    and looked at the relative number of cells from the
>two partners," says study
>                    co-author Dr. Otto Raabe, professor emeritus of
>radiation biophysics at the
>                    University. "We have a way of labeling the cells so
>we can tell which were
>                    from the radiation-exposed versus the 'control'
>cells." 
>
>                    The researchers then measured the "proliferation
>ratio" of the cells. "Basically,
>                    if nothing unusual happens, you'd expect to have
>about equal numbers in cells
>                    from both halves of the chimera," Raabe explains.
>"But cells from the
>                    irradiated parent do not proliferate, or divide, as
>fast. They have what we call
>                    a 'proliferation disadvantage.'" 
>
>                    The researcher says these decreases in proliferation
>were tied to paternal
>                    irradiation "with doses of gamma radiation to the
>backsides of the male mice."
>
>                    "The key here is that the radiation effect is on the
>developing sperm and it
>                    occurs at a specific point in the developing sperm,
>not on the mature sperm,"
>                    explains Raabe. During successive matings, at about
>six to seven weeks after
>                    radiation, "the embryos produced by conceptions at
>that time are the ones
>                    that have this effect (proliferation decrease). The
>ones produced earlier or
>                    later don't have this effect." 
>
>                    The researcher says the effect has been observed
>with radiation doses varying
>                    from 1 rem to 100 rem. And at 100 rem, the
>researchers found that the effect
>                    can be inherited by the offspring of the irradiated
>males. 
>
>                    The researcher says radiation exposure of 100 rem
>may apply to survivors of
>                    an atomic bomb blast. He notes that radiation
>therapy for cancer patients
>                    "could be much higher but is focused on certain
>areas of the body, not
>                    whole-body radiation at this level." He says 1 rem
>exposure is "within
>                    radiation worker acceptable levels." The one-year
>limit for radiation workers,
>                    such as workers in nuclear power plants and hospital
>workers involved with
>                    radioactive materials, is 5 rems. 
>
>                    "We haven't done any heritability studies at 1 rem,"
>Raabe says. "That's the
>                    next part of the study. But we've had the
>proliferation effect down to 1 rem." 
>
>                    "If this (the new study) is confirmed, then
>germ-cell irradiation during critical
>                    periods prior to conception may require special
>radiation safety
>                    considerations for radiation workers in their
>reproductive years," the
>                    researcher states. 
>
>                    SOURCE: Radiation Research (1997;148) 
>
>