Science goes to Space
MRC NEWS
When South African entrepreneur Mark Shuttleworth blasts off to be the first
African in space, he's also taking science with him. MRC-supported scientists
have designed experiments that he will perform while in orbit - a first for
African science.
Two young scientists, Karen Sharwood and Lara Keytel of the MRC's Exercise
Science and Sports Medicine Research Unit, share more than a passing interest in
Shuttleworth's space journey. And another MRC-supported scientist, Dr Vaughan
Oosthuizen from the Department of Biochemistry and Microbiology at the
University of Port Elizabeth, will also be watching the skies. These three
scientists have designed two of the three science experiments Shuttleworth will
perform while 'up there' in microgravity.
Dr Romilla Maharaj, Executive Director of the Research Development
Directorate of the MRC says we need to substantially increase the number of
highly trained scientists, engineers and technologists in our country: "Mr
Shuttleworth's mission will generate interest and curiosity, highlighting for
the youth in South Africa the limitless opportunities that science, engineering
and technology have to offer."
 Heart
rate and blood pressure
Mss Sharwood's and Keytel's study, titled The effect of a microgravity
environment on automatic cardiovascular control, energy expenditure and muscle
characteristics, aims to mine new information in an area where there is still
conflicting results, adding to existing scientific knowledge. This they will do
by taking simple heart rate and blood pressure measurements.
"What we will be doing is to use heart rate and blood pressure as health
and physiological measurements, thereby promoting the understanding of these
parameters as health measurements. We also want to promote the concept of
distance coaching - where we on Earth are going to monitor Mark in space,"
Ms Sharwood says.
She explains: "Both heart rate and blood pressure are controlled by the
automatic nervous system. This nervous system is an unconscious, or 'automatic'
nervous system, which consists of two parts - the parasympathetic and the
sympathetic nervous systems. These two systems have opposing roles and are
activated according to the different needs of the individual."
Fine balance
The parasympathetic system is activated during rest and assists in energy
restoration by means of the digestion and absorption of food. The system also
decreases the heart rate. The sympathetic system, on the other hand, prepares
the body for an emergency and counteracts the parasympathetic system in order to
maintain the required energy supply. During any emotional of physical stress,
adrenaline is released by the sympathetic nervous system, which acts to increase
heart rate and blood pressure.
"So the heart rate is controlled by the balance between the
parasympathetic and sympathetic nervous systems' activity. But on a beat-to-beat
basis, it has been observed that the heart rate is not constant and that there
are periodical fluctuations indicative of the relative contributions of each of
these two components," Ms Sharwood says.
According to her, there have been various methods employed in an attempt to
quantify the relative contributions of these systems. "One of the most
commonly used methods is the frequency domain analysis of heart rate
variability. This method uses highly sophisticated techniques to determine the
different frequencies of heart rate. From this analysis we can identify which
nervous system is predominantly active during both rest and exercise," she
says.
There have been very few studies conducted during space flights that have
measured this component of physiology - and those that have been done have
yielded conflicting results. "So the first aim of this study will be to
determine whether the relative contributions of the parasympathetic and
sympathetic systems remain the same in space when compared to Earth," Ms
Sharwood explains.
No pain, no gain?
A second aim of the study will be to provide Shuttleworth with a number of
specifically designed exercises that he will be able to do both before he leaves
for space as well as while he's in orbit. "Previous research has shown
that, although there's no muscle damage that occurs during space flight because
there is no gravity to load the muscles, as soon as the astronauts arrive back
on Earth they experience muscle pain and stiffness. This pain is similar to that
which we experience on Earth after participating in any unaccustomed or
strenuous exercise, and is caused by miniature tears to the muscle fibres,"
Ms Sharwood explains.
This pain is known as delayed onset muscle soreness (DOMS). Research has
shown that if an exercise causes this kind of response, it is likely that there
may be some protective effect on that muscle. "When the same exercise is
repeated later, this pain and muscle damage will be much less. So we aim to
significantly reduce Mr Shuttleworth's discomfort when he comes back to
Earth," she says.
Distance monitoring
Ms Sharwood says that their research of health and fitness has illustrated
the need for scientific communication - to take their expertise outside of the
boundaries of their building. "By studying Mr Shuttleworth in Russia and
aboard the International Space Station, we will begin to demonstrate and develop
distance coaching and evaluation, using such data as heart rate. We believe that
this experience will provide the necessary impetus and opportunity to develop
the capacity for distance coaching and evaluation throughout South Africa and,
in due course, the rest of the world."
Energy expenditure
Ms Keytel designed the energy expenditure part of the study. She explains:
"A component of space travel that has been extensively studied is that of
energy balance and energy expenditure. It has been found that astronauts lose a
significant amount of body weight during space flight, because their energy
expenditure stays the same, while dietary intake is significantly reduced. The
use of the doubly labelled water technique, a very accurate means of measuring
total daily energy expenditure (TEE), has previously been validated in space
with highly accurate results."
"But there is also another technique for measuring TEE, namely the heart
rate monitoring (HRM) method. Heart rate monitors provide relatively
inexpensive, non-invasive tools that allow for the accurate measurement of
energy expenditure, provided the person has been individually calibrated so that
they have created their own heart rate-energy expenditure curve."
"We are going to compare the efficacy of the two methods in space. If
HRM is proved to be an accurate measure of TEE, when compared to the doubly-labelled
water technique in micro-gravity, then this should strengthen the case for the
use of this method on Earth and encourage the use of this relatively inexpensive
method among large groups of people in group-based population studies," she
says.
This would be of special importance in our country where chronic diseases of
lifestyle including heart disease, hypertension, diabetes and obesity are on the
increase. According to Ms Keytel, the underlying factor contributing to most of
these diseases has been shown to be physical inactivity, as expressed by TEE.
"Heart rate and blood pressure are both practical measurements of health
that the South African and international public can relate to. This research
project aims to promote the understanding and importance of these variables and
how they are affected during physical activity," she says.
Internet
Both Shuttleworth's heart rate and blood pressure will be downloaded to the
Internet to a South African-based website at www.bodyiq.com, driven by Body iQ.
This is a company which has developed a novel method to measure and promote
health (read more in MRC News, October 2000). They will analyse and interpret
the information that is received from space and put it on the website. This will
be a world first.
"The exposure of Mr Shuttleworth's heart rate, blood pressure and total
daily energy expenditure to the public will create maximal awareness of health,
as well as aiding in the promotion of the use of physical activity in the
improvement of health in South Africa," says Ms Keytel.
Growing protein crystals
Another, very different experiment is that of Dr Vaughan Oosthuizen. In his
experiment two types of soluble immunoglobulin receptor proteins will be
crystallised, so that their structure and precise function can be solved by
X-ray crystallography. To grow such 'protein crystals' is extremely difficult
and complex, but past experience has shown that it happens more readily under
conditions of microgravity.
Dr Oosthuizen explains: "Immunoglobulin receptor proteins (FcR)
expressed on the surface of all immune cells mediate most humoral immune
reactions. These reactions ensure a broad and efficient immune reaction by
triggering the uptake of immune complexes, by regulating antibody production and
by release of other 'chemicals' that activate other immune cells."
At the same time, FcRs also mediate abnormally regulated immune reactions
causing common conditions of allergies, asthma, infections, autoimmune disease
and cancer. "FcRs are also prime targets of several serious virus
infections, for example HIV/AIDS, Ebola, measles and Dengue. So these FcRs are
ideal targets for immunotherapy," says Dr Oosthuizen.
One such FcR, called FcRII, was discovered in the late 1980s and is believed
to be the central molecule in allergic responses. It has very diverse functions,
from cell adhesion to the growth of B and T cells, to mention but a few. Soluble
and membrane-bound forms are found, but the precise functions of the soluble
forms still elude scientists. This project aims to grow crystals of this FcR, so
that it can be studied by X-ray crystallography to elucidate the structure, so
that scientists can design better immune therapies.
A second receptor protein of interest to Dr Oosthuizen, is FcRIII. It is
known that HIV infectivity is increased by the presence of certain antibodies in
the human blood circulation, which raises questions about the usefulness of
vaccinations against the virus. The FcRIII was shown to be responsible for this
antibody-induced increase in HIV infectivity.
"We have recently solved the structure of FcRIII , but crystallisation
of this protein under microgravity conditions will hopefully improve the quality
of the crystals and allow higher resolution structures to be determined for the
protein. This will aid our understanding of the structural and thermodynamic
mechanisms of the interaction between the FcRIII and IgG, and ultimately to
immune therapies that could block this interaction. Such immune therapies would
also be potentially capable of reducing the antibody-enhanced infectivity of
HIV," Dr Oosthuizen says.
Article courtesy of the MRC News.
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