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Dec 12, 2012 (5 years and 25 days ago)

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Genetic Engineering

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Biology Honors Genetic Engineering Secondary Research Paper







Genetic Engineering Secondary Research

Jason Chang

Mark Keppel High School

April 13, 2012



Genetic Engineering

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Genetic Engineering Secondary Research Paper


This planet sustains various life forms and over
time these
organisms have evolved to better survive in the environments in which
they live. Humans are constantly trying to improve the world and the
organisms in it. In order to achi
eve this goal, there is a powerful
tool scientists are using called DNA T
echnology. It is that technology
that allows humans to modify, create, and/or destroy life, as we know
it.
Genetic engineering is

applied techniques of genetics and
biotechnology used to cut up and join together genetic material and
especially DNA from one

or more species of organism and to introduce
the result into an organism in order to change one or more of its
characteristics.
It started in
circa
1951.

The purpose of this paper
is to: (a) review genetically engineered herpes simplex virus; (b)
review b
-
TCP zirconia/ polymeric biocomposites; (c) discuss which one
is more useful to humans.


Review

Genetically Engineered Herpes Simplex Virus


Genetically engineered

(GE)

virus
es

"are increasingly being
considered for experimental therapy of brain tumors" (Chambers et al,

1995,

p.
1411
)
.

Tumors are an uncontrolled growth or mass of body cells,
which may be malignant or benign and has no physiological function. It
can often lead to
death of the organism.
Simplex virus is a genus of
double
-
stranded DNA viruses of the family
Herpesviridae

that usually
infect primates and that tend to persist in the host as latent
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infections in neurons
.

Studies have shown that genetically engineered
her
pes simplex virus is very effective in killing tumor cells in both
murine tumor models and
in vitro

environments

and they do not have the
ability to multiply in the central nervous systems of rodents
.
Investigations have

mainly focused on the exploitation of viruses as
either direct therapeutics or for the transfer of genetic information.

Genetically engineered herpes simplex virus "expressing various
cytokines can improve survival… These attenuated viruses have both
copi
es of
y
1
34.5

deleted" (Parker et al, 2000, p.2208).


Two approaches have been experimented in treating
the tumors. The
first one involves deliberate
in situ

injection

of cells infected with
a retrovirus expressing
the
herpes simplex virus 1 (
HSV
-
1
)

thymidine
kinase gene into the tumor mass followed by treatment with
ganciclovir
(GCV)
, "
an antiviral drug C
9
H
13
N
5
O
4

related to acyclovir and used
especially to treat cytomegalovirus retinitis in immunocompromised
individuals" (Merriam
-
Webster Dictionary,

2012)
. The retrovirus is
secreted from the inoculated cells and infects the tumor cells
. GCV is
"
selectively phosphorylated by the HSV
-
1 thymidine kinase to its
monophosphate
derivative

and by
cellular enzymes to a triphosphate
derivative
, which kills the

tumor cells
" (Chambers et al, 1995,
p.1411)
.

This approach is being investigated in clinics
at the
National Institutes of Health. On the other hand, this method is very
limited.


An alternative method to the one stated above uses genetically
engineered
HSV.

The mutants tested were viruses missing the thymidine
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kinase or ribonucleic reductase

gene or GE virus missing the
y
1
34.5
gene. Even though the viruses we able to prolong
the life of the
tumor
-
carrying animals, none were fully cured.


HSV
-
1 causes
"
a
n initial

mild to asymptomatic infection

after
transmission to cells of mucous membranes" (Andreansky et al, 1997,
p.1502). Tests have shown that R3616 and R4009 HSV have noticeably

lengthened the life of the
scid

mice having mouse glioma.

b
-
TCP Zirconia/
Polymeric Biocomposites


Hydroxyapatite
-
alumina
-
zirconia composite is the most likely
material for bone replacement.

Hydroxyapatite is a hydrated calcium
phosphate mineral. Alumina is a white colorless oxide of
aluminum, and
zirconia is a heavy water insol
uble white powder
.

Commercial grade
"
hydroxyapatite, alum ina and yttria stabilized zirconia were mixed in
varying proportions and obtained powders were sintered
up to

1300 °C
subsequent to dry pressing at 160MPa" (Sahin, 2006,
p.
iv).
Bioceramics
are mater
ials that
most matches to real bones. The goal is to
"synthesis
e

(synthesize)

a biocomposite composed of bioinert and tough
zirconia toughened alumina and bioactive hydroxyapatite in the
nanoscale by colloidal methods" (Sahin, 2006, p.2).


b
-
tricalcium
phosphate (b
-
TCP) and polymeric matrix are able to
fabricate novel biocomposites
. B
-
TCP ceramics "have been
commercialized as bioresorbable (the ability of a biomaterial to be
digested by or as a consequence of cellular activity, and thus
dissolve or disap
pear in part or in whole after implantation)
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synthetic bone substitutes and are and

are

used

in orthopedic and
dental applications, including augmentation of the alveolar ridge,
sinus reconstruction and bone substitutes…" (Mohamed et al, 2011,
p.111).
Zirc
onia can be used as a replacement for alumina for the
ceramic ball heads of hip replacement because it is tough.

Discussion


In my opinion, I think that using genetically engineered herpes
simplex virus to treat brain tumors is more useful to the human
world.

Biocomposites to be bone replacement is also quite useful, but humans
do not need it as much as curing tumors.

Although

this is still
pioneer technology and is not guaranteed to fully cure tumors but it
have been proven to at least prolong the survi
val
of the tumor
-
bearing
animals.

However, the require use of ganciclovir,
poses a possibility
for serious side effects of the drug and can lead to death.
The doctor
uses the virus

cure
your

tumor and then
the patient gets

kill
with the
drug.


The
alternative method only has shown to prolong the life of the
organism but didn’t cure it from the tumor. Basically, it is not
useful in curing the patient. The most it do
es is stall death of the
person, while we discover new and
b
etter methods.


By using
genetic engineering, we can fix this
cell
mutation and
save

many

lives.

It is a breakthrough in medicine and I will strongly
encourage the continuation of this research
.
The world

can finally
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reach a point in which
tumors can be successfully cures without
killing the host. We make the future!



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Works Cited

Andreansky, Samita, et al. "Evaluation of Genetically Engineered
Herpes Simplex Viruses as Oncolytic Agents for Human Malignant
Brain Tumors."
Cancer Research

(1997): 1502
-
1509. Primary Source.

Chambers, Renee, et al. "Comparison of genetically engineered herpes
simplex viruses for the treatment of brain tumors in a scid mouse
model of human."
Medical Sciences

(1995): 1411
-
1415. Primary
Source.

Mohamed, Khaled
R., Mohamed Amr M. and Hanan H. Beherei. "Synthesis
and in vitro behavior of b
-
TCP zirconia/polymeric biocomposites
for bio
-
applications."
Journal of Genetic Engineering and
Biotechnology

(2011): 111
-
119. Primary Source.

Parker, Jacqueline N., et al. "Engi
neered herpes simplex virus
expressing IL
-
12 in the treatment of experimental murine brain
tumors."
PNAS

(2000): 2208
-
2213.

Sahin, Erdem.
SYNTHESIS AND CHARACTERIZATION OF HYDROXYAPATITE
-
ALUMINA
-
ZIRCONIA BIOCOMPOSITES
. Masters Degree Thesis. Izmir,
2006. P
rimary Source.