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Growth Hormone Releasing Hormone,
or GHRH, is a naturally occurring molecule with similar
characteristics and activity in humans and other animals. GHRH is
a key potentiator of the GHRH - Growth Hormone (GH) - Insulin like
growth factor (IGF-1) axis. Studies in different animal models and
humans have shown that GHRH has both direct and indirect functions
in development, muscle metabolism, and maintenance of hematological
and immune status under physiological and pathological conditions.
The creation of myogenic plasmid vectors that express GHRH has been
a significant advancement in the use of GHRH to treat conditions such
as cachexia and anemia, to optimize development, and to stimulate
immune function. VGX Animal Health has developed species-specific
DNA plasmids that can be injected into a skeletal muscle, are not
integrated into the cell’s genome, and are expressed by muscle
cells for desired periods of time. Plasmid uptake can be enhanced
by electroporation. Studies have demonstrated expression for up to
two years in large animal models such as cows and pigs. No repeat
treatments are necessary within this time period. This innovative
method allows GHRH to be naturally produced and maintained by the
animal’s own natural physiologic feedback mechanisms.
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Pre-clinical animal models:
Plasmid-based GHRH technology
has been developed by ADViSYS, Inc., now part of VGX Pharmaceuticals. |
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Extensive testing
has been conducted for safety and efficacy in several food and
companion animal species (cattle, pigs, dogs, cats and horses),
as well as laboratory animals (mice and rats). |
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Long-term hematological and quality
of life parameters were improved after a single plasmid GHRH
administration in dogs with malignancies or
geriatric disabilities. |
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Preliminary studies on dogs
and cats with renal failure showed that the
treatment resulted in correction of anemia, while renal function
was maintained. |
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In directly treated cattle,
plasmid-mediated GHRH supplementation stimulated T cell and
natural killer cell numbers that may be associated with an improvement
in immune function, nutritional and health parameters. |
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The clinical consequences in
cattle were a significant reduction in morbidity
and mortality as well as improved body condition scores and
milk production compared to control animals. |
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Recent results in rats,
pigs and cows have also demonstrated that when pregnant
animals are administered plasmid-mediated GHRH supplementation,
they give birth to healthier offspring. |
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Offspring of plasmid-mediated
GHRH treated pigs demonstrated a decrease in
mortality of 57% compared to offspring from untreated animals. |
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Morbidity in offspring from treated
animals was substantially reduced suggesting the potential for
discontinuation of routine antibiotic treatments. |
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Horses with chronic arthritis/laminitis
had significant improvements in body condition, metabolic profiles
and resolution of lameness. |
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