Download Biotechnology and Bioinformatics: Medicine

Biotechnology and
Bioinformatics: Medicine
Essential Idea: Biotechnology can be used in
the diagnosis and treatment of disease.
TOK
There have been cases around the world where
subjects have died as a consequence of participating
in a gene therapy research protocol. How is the
decision to proceed with risky procedures made?
What constitutes an acceptable level of risk for
allowing humans to be involved in scientific research?
ELISA Tests
Pathogens can be detected
using a variety of molecular
techniques.
One popular method is to use
an ELISA test. “ELISA”
stands for Enzyme Linked
Immunosorbant Assay.
This method allows for rapid
detection of a specific
disease that allows for quick
treatment of an affected
individual.
www.bio-rad.com
ELISA Test
ELISA tests involve
multiple steps:
In the first step, the
sample in question is
placed into a sample
well plate and then
washed out. Some of
the sample will
adhere to the sides of
the well plate.
http://technologyinscience.blogspot.com/2011/12/elisa-protocol-types-of-elisa.html#.VgtFsrRVhBc
ELISA Test
A primary antibody is
then added to the well
plate which will bind
to any of the antigens
in the original sample.
http://technologyinscience.blogspot.com/2011/12/elisa-protocol-types-of-elisa.html#.VgtFsrRVhBc
ELISA Test
The wells are then
washed again.
A secondary antibody
which has an enzyme
attached to it is then
added to the well plate.
The secondary antibody
(along with the enzyme)
will then bind to the
primary antibody which
was bound to the
antigen.
http://technologyinscience.blogspot.com/2011/12/elisa-protocol-types-of-elisa.html#.VgtFsrRVhBc
ELISA Test
An enzyme
substrate is then
added to the wells.
This substrate will
react with any
enzyme present and
indicate a positive
result from the
original sample.
http://technologyinscience.blogspot.com/2011/12/elisa-protocol-types-of-elisa.html#.VgtFsrRVhBc
Metabolomics
Metabolomics is a rapidly
expanding field of study
dedicated to the
detection of metabolites
in biological systems.
Metabolites that indicate
disease can be detected
in blood and urine.
http://www.intechopen.com/books/calcific-aortic-valve-disease/proteomics-and-metabolomics-in-aortic-stenosis-studying-healthy-valves-for-a-better-understanding-of
Metabolomics
For instance, urine samples can be used to detect
breast and ovarian cancer.
If these cancers are detected at an early stage, the 5year survivability rates exceed 90%.
http://www.metabolon.com/technology/about-metabolomics.aspx
Metabolomics
PKU is a metabolic disorder that results in severe
intellectual disability caused by elevated serum
phenylalanine levels.
The primary cause is phenylalanine hydroxylase
deficiency.
Blood tests can be used to detect phenylalanine
levels, and appropriate clinical steps can then be
taken to manage the disease.
Marker Genes
Some people are predisposed to a genetic disease
based upon the whether or not a family member has
been afflicted with the disease.
Tests can be run to determine whether or not you will
inherit the disease.
These tests look for genetic markers.
Marker Genes
For instance, Huntington’s disease is a
neurodegenerative disorder that affects some people
in mid-life.
Those who get it usually die within a few years of
diagnosis.
It is a dominant gene. Thus, if a mother or father
have it, you have a 50/50 chance of inheriting it.
Marker Genes
Tests can be run to look for markers in the genome to
determine the likelihood of developing the disease.
DNA Microarrays
DNA microarrays
enable scientists to
study multiple genes
in one experiment.
This is very useful
due to the
tremendous
numbers of genes
found within
organisms.
https://commons.wikimedia.org/wiki/File:DNA_microarray.svg
DNA Microarrays
DNA microarrays have many
uses, but some of the
common ones include:
Measuring changes in the
expression levels of
genes (expression
analysis).
Detecting single
nucleotide
polymorphisms.
Determining the genotype
of an organism.
https://mla-lima.wikispaces.com/Southern+Blotting+and+DNA+Microarray
DNA Microarrays
For example, when gene
expression is being
monitored with a microarray,
thousands of genes can be
simultaneously monitored.
The results can be used to
compare the level of gene
expression in diseased
tissue to that of a normal
tissue.
This can help to improve
treatment methods/options.
http://cisncancer.org/research/how_cancer_is_studied/background/research_technology_02.html
DNA Microarrays
DNA microarrays can also be used to detect
predisposition to disease.
The information gathered can be used to inform
individuals about environmental factors that may
trigger certain genetic diseases.
PCR Uses
PCR can be used to detect
a wide variety of
biomolecules.
It can be used in crime
scene analysis, tissue
typing, and disease
outbreak/diagnosis, among
many other things.
We used it in class to detect
the presence of GMOs in
foods.
www.thermofisher.com
PCR and Influenza
Detection
PCR is widely used to detect and track new strains of
influenza.
Due to the rapid, sensitive, and specific assay that is
followed, governmental agencies are given the
opportunity to quickly respond to emerging threats,
and take the appropriate measures to protect citizens.
http://path.upmc.edu/virology/s-01.htm
Tumor Cell Tracking
Tracking experiments are used
by researchers to gain
information about proteins, their
interaction within the cellular
environment, and what the
localization of these proteins
within the cell can tell them.
Advances in biotechnology have
also enabled researchers to use
tracking experiments to track
tumor cells using transferrin
linked to luminescent probes.
https://www.mskcc.org/blog/new-imaging-agent-could-improve-prostate-diagnosis-and-treatment
Tumor Cell Tracking
Transferrin is an ironbinding blood plasma
glycoprotein normally
present in the bloodstream
and binds to fast-growing
cells such as tumor cells
(as well as fast dividing
normal cells).
Its main job is to control the
level of free iron in body
fluids.
http://biologie.ens-lyon.fr/ressources/bibliographies/m1-12-13-biosci-reviews-curis-c-1c-m.xml
Tumor Cell Tracking
Scientists are using PET scans
to track transferrin uptake in
tumor cells.
With this strategy, they can
assess the speed at which the
iron is taken up by the cells to
monitor how rapidly the tumor
may be growing.
This allows for early disease
detection before any tumor
growth can be seen with
conventional imaging
techniques.
https://www.mskcc.org/blog/new-imaging-agent-could-improve-prostate-diagnosis-and-treatment
Tumor Cell Tracking
Here’s how it works:
Scientists have developed a way to couple transferrin
to a radionuclide called zirconium-89.
Transferrin is rapidly taken up by actively dividing
cells, and zirconium-89 is easily detected by a PET
scan.
http://www.nature.com/nm/journal/v18/n10/full/nm.2935.html?WT.ec_id=NM-201210
Tumor Cell Tracking
These two tools produce
very high quality images that
enable researchers to better
understand and design
treatments for cancer
patients.
QuickTime™ and a
GIF decompressor
are needed to see this picture.
https://en.wikipedia.org/wiki/Positron_emission_tomography
Gene Therapy and Viral
Vectors
Viral vectors are used in gene therapy.
Gene therapy is a method of inserting a gene into an
organism that does not have it.
The gene must be inserted into a spot on the
chromosome where it will be actively expressed.
The gene must also be inserted into a cell that can be
transplanted into the organism where it can proliferate
and take up long term residence.
SCID
SCID (severe combined
immunodeficiency) is a
disease in which the patient
cannot make antibodies nor
can mount a cell-mediated
response to an antigen.
It is a disease of young
children because most
children get infected with
an illness that kills them.
http://labs.pathology.med.nyu.edu/feske-lab/research/immunodeficiency
SCID
About 25% of all patients
are the result of being
homozygous recessive
for a defective gene
coding for adenosine
deaminase.
This faulty purine
metabolism creates a
situation that is toxic to T
and B cells--cells
needed for proper
immune system function.
http://primaryimmune.org/about-primary-immunodeficiencies/relevant-info/inheritance/
SCID Treatment Options
Raise the child in a
bubble.
Regular bone marrow
transplants.
This can pose problems
if the donor is infected.
Regular injections of ADA
(adenosine deaminase).
Insertion of ADA genes
with a retrovirus as a form
of gene therapy.
http://www.worldmag.com/2014/12/with_breakthrough_parents_can_finally_hug_and_kiss_their_bubble_babies
Gene Therapy for SCID-How it Works.
First you need to identify and clone a normal copy of
the ADA gene.
The gene then needs to be inserted into the DNA of
one of the patient’s own cells. This is done with a
retrovirus and reverse transcriptase.
The gene needs to be inserted into a spot where it will be
adequately expressed (transcribed and translated) thus
producing reasonable amounts of enzyme.
Treating the cells in tissue culture so they multiply,
and then returning them to the patient.
Gene Therapy for SCID
To get the DNA into the
cell, a retrovirus is used
as the vector. This
makes use of an
envelope protein
enabling the virus to
infect the human cell.
RNA copies of the
human ADA gene can
then be incorporated into
the retroviral genome
using a packaging cell.
http://learn.genetics.utah.edu/content/genetherapy/gtsuccess/
Gene Therapy for SCID
Packaging cells are:
cells that express an RNA copy of the (ADA)
gene,
cells that have an RNA copy of the retroviral
genes to assist in the copying of the genes which
need to be expressed,
cells that contain inverted repeats to assist with
the insertion of the DNA into the DNA of the target
cell.
Packaging cells lack the genes
necessary for critical viral replication.
They become proviruses that replicate
as the cell divides.
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/GeneTherapy.html
Gene Therapy for SCID
Retroviruses are often altered
and used for gene therapy.
Researchers insert the
desired gene(s) into the virus
and then remove the coding
regions for the genes needed
by the virus to replicate itself.
Thus, these viruses are
capable of infecting their
target cell, but are unable to
continue their destructive life
cycle.
http://learn.genetics.utah.edu/content/genetherapy/gtsuccess/
Gene Therapy for SCID
If the gene is inserted
correctly, in this case
the ADA gene, the
cells begin
synthesizing the
enzyme needed to
produce adenosine
deaminase and the
patient’s immune
system begins to
function normally.
http://www.mun.ca/biology/scarr/Somatic_Therapy_for_SCID.htm
Gene Therapy for SCID
Gene therapy for SCID involves some risks:
4 of the 10 patients undergoing SCID gene therapy developed
leukemia as a result of the ADA gene being inserted near an
oncogene.
2 of the 4 patients were successfully treated.
Other methods of gene insertion have also been
explored.
Gene Therapy for SCID
Using adeno-associated
viruses, for example,
have been shown to be
much safer because they
always integrate in the
same spot on a
chromosome and are
designed to insert in
spots not known to
cause problems.
https://en.wikipedia.org/wiki/Gene_therapy