Download Unit K: Challenges to Biomedical Research

Unit K: Challenges to
Biomedical Research
Objective BT11.01: Interpret
personal beliefs about
biomedical research
Interpret personal beliefs
about biomedical research.
Beliefs about biomedical research
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Differences between fact and opinion
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What do you believe?
Fact: information & ideas that can be supported
by data & can be proven
Opinion: a belief not based on certainty
Fact vs. myth in research
Role of animals in society
Objective BT11.02:
Analyze transgenic
animals.
Analyze transgenic animals
Early beginnings
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Biotechnology – collection of scientific
techniques that use living cells and molecules
to make products and solve problems
1. Transgenic organisms = Organisms that
contain another species’ genes within their
chromosomes
transgenic animals
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2. Historically – used in selective
breeding of livestock, controlled plant
pollination, and microorganisms to
bake bread, brew beer and make
cheese
transgenic animals
3. This is accomplished by
transferring specific genes
from one species to another
4. First transgenic organisms
were bacteria
transgenic animals
5. Scientists around the world use
customized transgenic animals for their
own research
 6. Species include sheep, goats, cows,
chickens, pigs, mice, rabbits, rats,
chickens and fish
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Benefits of transgenic animals
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Animal models
Pharmaceutical production
Organ donors
Livestock improvement
Production of transgenic animals
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The transgene (which contains the
DNA the scientist wants to transfer) is
introduced into a single-cell embryo
The embryo is transferred to a
surrogate mother of the same strain
Success rate is low (10%-30%) in mice
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Success rate decreases in mammals
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Care of transgenic animals
Most do not require special
care
Some develop a susceptibility
to disease
Government’s role in transgenic
research
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U.S. Patent and Trademark Office
issues patents for transgenic
animals
Only government policy is the NIH
Guidelines for Research Involving
Recombinant DNA Molecules
Ethical considerations
1. People opposed to transgenic animal research
believe:
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Increases animal suffering
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Animals with altered genetic characteristics
could threaten our environment, our health and
food supply
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Scientist are “playing God”
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Concerned that scientist will use these
techniques on humans
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2. Beliefs of people who favor transgenic animal
research
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Transgenic animal models provide a powerful new way to
study diseases
Vital substances needed by the human body may soon be
available at a reasonable cost
Sufficient numbers of human organs are not available for
transplantation and transgenic animals may provide a new
source of organs
Transgenic techniques may one day be used to treat
human diseases such as sickle cell & cancer
Future of transgenic animals
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Current research limited to transferring a
small amount of genes at a time
Much work remains to be done to fine-tune
techniques
Possible effects of foreign DNA remains a
concern
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The use of transgenic models is an
established part of biomedical research in
numerous fields:
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Immunology
Pharmacology
Neurology
Cancer research
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“pharming”
although still in the
research phase, may soon
dramatically increase the
availability of scare and muchneeded human substances, and
at a much lower cost
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Biotechnology companies are already
producing transgenic pigs whose offspring
may alleviate the desperate shortage of
organs for human transplantation.
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Transgenic pigs with human histo-compatibility
genes have been bred in the hope that their
"humanised" organs will not be rejected by a
patient's immune system. Although in its infancy,
if successful, this research could transform the
lives of the many patients awaiting organ
transplants
From SGK
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Gene-based biomedical research offers one of the best hopes yet
for curing the major diseases which still afflict mankind. The use of
transgenic animals is central to realising that hope and offers the
potential for the use of fewer animals in more targeted experiments.
We must be clear. There are only two alternatives to using animals.
One is to use humans in basic research; the other is to delay or
even give up the search for desperately needed new treatments and
cures. The appropriate use of transgenic animals is a positive
development with potential for significant medical benefits. The
challenge is for governments, industry and society to ensure that
transgenic research continues to be sensitively carried out for proper
medical ends in a suitably balanced regulatory environment.
Objective
BT11.03:
Evaluate therapeutic vs.
reproductive cloning.
History of cloning
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Dolly the sheep
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Born: 5 July 1996
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Birthplace: Edinburgh, Scotland
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Died: 14 February 2003 (euthanization)
Best Known As: The first cloned mammal
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Dolly was history's first cloned mammal. In February of 1997 it was announced that
the biotechnology firm PPL Therapeutics and the Roslin Institute of Edinburgh,
Scotland had successfully cloned a sheep, under the direction of Dr. Ian Wilmut. Cells
from the udder of a pregnant six year-old sheep were inserted into the uterus of
another sheep to develop, and Dolly was born in July of 1996. (Her name was a sly
nod to singer Dolly Parton.) Dolly had the DNA of her source, making her the first
mammal successfully cloned using adult cells. Dolly was put to sleep in 2003 after
doctors detected progressive lung disease, though she had only reached half the life
span of a typical sheep.
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Very few scientists believe human cloning
(reproductive cloning) should be permitted
Many scientists in favor of therapeutic cloning –
the procedure used to produce embryonic stem
cells that theoretically can be used to treat
diseases
What is a clone?
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Clone = precise genetic copy
Reproductive cloning is really somatic cell
nuclear transfer (SCNT)
In therapeutic cloning, the embryo is not
placed in a surrogate, but rather, undergoes
cell division in the lab until it reaches
blastocyst stage
Obstacles to reproductive cloning using
animals
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Success rate very low
Vast majority of problems occur during fetal
development
Additional problems show up after birth and
years later
“Large offspring syndrome” = cloned newborns
20-30% larger than usual, making it hard to
deliver unborn babies
Embryonic and adult stem
cells
Adult stem cells
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Multipotent stem cells
Exist in very small numbers throughout the
body
Most accessible ones are the blood stem cells
that reside in bone marrow
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Embryonic stem cells
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Called pluripotent stem cells
Have the potential to become many types of cells
Embryonic stem cells occur at about 4 days of cell
division
cloning, therapeutic cloning, and stem cell
research
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Goal of reproductive cloning is to create a new
organism, human or animal
Goal of therapeutic cloning is to produce
embryonic stem cells
Identical Twins
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Natural cloning
Takes place during the first rounds of cell
division after conception when each cell had
the potential to form a fetus
Human stem cell research
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2001 legislation allowed federal funding of
research using 64 existing human embryonic
stem cells
Same legislation declared no federal funds for
additional research.
Obama has overturned this in his first year of
office allowing funding for new lines of stem
cells
Therapeutic potential of stem cells
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Researchers must use existing human stem cell
lines for research or find private funding
sources
Creation of embryonic stem cells does not use
fertilized egg
On the other hand, it does have the potential to
become a living thing if transplanted into the
uterus
Question – is life destroyed if the stem cells are
removed from the blastocyst four days later?
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Therapeutic potential of stem cells (con’t)
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Real advantage of stem cells – permits the
production of perfect-match tissue
Scientists have found that embryonic stem cells
pick up cues from neighboring cells and
differentiate into that cell type
Scientists hope stem cells will be used to treat
heart disease, Parkinson’s disease, other
disorders of the nervous system
Objective BT11.04:Debate pros
and cons of animal research
and animal rights.
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Debate pros and cons of animal research and
animal rights.