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Frequency Asked Questions
Following are frequently asked questions
regarding the use of osmolality in the pharmaceutical,
biotechnology, and sports
medicine applications.
Pharmaceutical
1. What is tonicity?
a. The normal state of slight contraction, or readiness to contract, of
healthy muscle fibers.
b. The effective osmotic pressure of a solution.
In pharmaceutical parenteral drug solutions tonicity can be adjusted in
hypotonic solutions by adding dextrose or sodium chloride.
2. Why is this important for pharmaceutical manufacturers?
Pharmaceutical solutions that are meant for application to delicate membranes
of the body should be adjusted to approximately the same tonicity as that
of the body fluids.
3. What does isotonic mean?
Isotonic solutions cause no swelling or contraction of the tissues with
which they come in contact, and produce no discomfort when instilled in
the eye, nasal tract, or other body tissues.
4. What does hypotonic mean?
The tonicity of the solution is less than that of the cells. When this
occurs, water enters into the blood cells causing them to swell and finally
burst, with the liberation of hemoglobin, or water invasion of the body’s
cells. If this invasion is beyond the body’s cells, then water intoxication
results, with convulsions and edema.
5. What does hypertonic mean?
The tonicity of the solution is greater than that of the cells, which
can cause a variety of complications, such as, hyperglycemia, intracellular
dehydration, loss of water and electrolytes, dehydration and coma.
6. What is crenation?
The water within the cell membrane attempts to dilute the surrounding
salt solution until the salt concentrations on both sides of the erythrocyte
membrane are identical. This outward passage of water causes the cells
to shrink and become wrinkled or crenated. The salt solution in this instance
is said to be hypertonic with respect to the blood contents.
The red blood cell (R.B.C.) is not impermeable to all drugs, i.e., it
is not a perfect semipermeable membrane. Thus, it will permit the passage
of not only water molecules, but also solutes such as UREA, ammonium chloride,
alcohol, and boric acid. The molecules of these compounds can cross the
R.B.C. and cause hemolysis at any concentration. The mucous lining of
the eye acts as a true semipermeable membrane to boric acid in solution.
Hence, boric acid can be used for ophthalmic solution to adjust tonicity.
7. When eating foods with high osmolality due to high electrolytes,
amino acids and simple sugars, why do people suffer discomfort?
When nutrition of high osmoticity is ingested, large amounts of water
will transfer to the stomach and intestines. Large amounts of water in
the gastrointestinal tract can cause distention, cramps, nausea, vomiting,
and shock.
The body tries to keep the osmoticity of the contents of the stomach and
intestines at approximately the same level as that of the fluid surrounding
them. There is great variation from one individual to another in sensitivity
to the osmoticity of foods.
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Biotechnology
1. Why are some cell culture
media better than others?
Media originally used for growth of mammalian cells were based on
biological fluids, such as plasma. This type of media suffered many disadvantages
including batch variation and vulnerability to contamination.
2. What other media is more
robust?
Reduction in the number of components in media design is essential
for cell growth. Eagle’s basal media (BME) and Eagle’s minimum
essential medium have found wide-ranging uses and are both available commercially.
3. What is media composed
of?
Formulations include a complex mixture of salts, carbohydrates, amino
acids, vitamins, hormones, and growth factors. The salt concentration
needs to be isotonic to prevent osmotic imbalances.
4. What should the osmolality
be for growth media?
The osmolality of standard cell growth media for mammalian cells is 300mOsm/kg,
an optimal value for most cell lines.
5. How can cell culture
media be made?
One of the most common methods used today is by utilizing a bioreactor.
A bioreactor allows the growth of human tissues outside of the body that
amass and behave like those in the body.
Another is the Rotary Cell
Culture System, as it provides a gentler environment than a dynamic or
static tissue culture system, thereby allowing cells to aggregate, grow
3-dimensionally, and differentiate. The result will be cells or tissues
that closely resemble the in vivo tissue equivalent.
Links:
www.nccc.com
www.cellculturechat.com
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Sports Medicine
Hydration and Dehydration FAQs
1. What is the definition of dehydration?
The lack of adequate body fluids needed for the body to carry on normal
functions at an optimal level. Dehydration can be caused by fluid loss
(through vomiting, diarrhea or excessive urination), inadequate intake,
or a combination of both. The most common cause of dehydration in infants
and children is acute gastroenteritis with its associated vomiting and
diarrhea.
Dehydration is classified as mild, moderate, or severe based on the percentage
of body weight lost during the acute illness. Depending on age, mild dehydration
is seen with a loss of 3-5% of body weight. Moderate dehydration is seen
with a 6-10% loss of body weight. Severe dehydration, which is a life-threatening
emergency, occurs when more than 9-15% of body weight is lost.
2. What causes dehydration during exercise?
Causes of dehydration include excessive fluid losses due to excessive
sweating, inadequate fluid intake, or a combination of these factors.
3. What are signs of dehydration?
Mild
Thirst
Dry lips
Slightly dry mouth membranes
Moderate
Very dry mouth membranes
Sunken eyes
Sunken fontanelle (soft spot) on infant’s head
Skin doesn’t bounce back quickly when lightly pinched and released
Severe
All signs of moderate dehydration
Rapid, weak pulse (more than 100 at rest)
Cold hands and feet
Rapid breathing
Blue lips
Confusion, lethargy, difficult to arouse
4. How should lost fluids
be replaced?
In cases where losses aren’t severe, athletes can replace these fluids
by drinking isoosmotic beverages that will serve to replace lost nutrients
and electrolytes.
In severe cases of dehydration, athletes are put on IV lines on-site or
in a hospital.
5. Why are sports beverages popular?
When a workout period exceeds 60 minutes, sports drinks can be beneficial
because they provide a source of fuel for working muscles and will speed
the absorption of water and glucose (sugar) from the small intestine.
Sports beverages are recommended for activities lasting longer than one
hour. (Drink plain water before or during activities lasting 60 minutes
or less). With sports drinks, continued exercise won't deplete muscle
glycogen as fast and performance time may be lengthened. Sports drinks
can also help reduce recovery time by rapidly restoring muscle glycogen
after exercise. Sports drinks are also beneficial when exercising in high
heat or humidity, the electrolytes help to enhance fluid absorption.
6. When should sports beverages be used?
Sports drinks are helpful before, during and after exercise. Sports beverages
are scientifically formulated to help restore the essential fluids, energy,
and minerals your body loses during exercise. The carbohydrate concentration
and sodium combination in a sports drink assures rapid hydration and improved
performance.
7. How should sports beverages be used?
Recommendations when taking a sports beverage:
The quality of carbohydrate needed to improve performance can easily be
met by consuming a sports beverage under the following recommendations:
Before exercise:
• Drink 8 to 24 ounces of a sports beverage 2-4 hours before exercise
or
• Drink at least 4 to 8 ounces of a sports beverage immediately before
exercise
During exercise:
• Drink 4 to 8 ounces of a sports beverage every 15-20 minutes after
the first 30 minutes of exercise
After exercise:
• Drink at least 8 to 16 oz of fluid after exercise. (drink 2 cups
of fluid for every pound lost after exercise)
• Consume or drink 40-60 grams of carbohydrate ASAP or within the
first 30 minutes after exercise, and at 2 hour intervals up to 4 hours
after exercise
8. What is the difference between drinks for hydration, energy and
recovery?
An energy drink contains a significant amount of carbohydrate; this is
going to reduce the hydration benefits of that drink.
A hydration drink will not provide sufficient carbohydrate for times
of glycogen depletion.
A recovery drink will not provide rapid energy absorption and hydration
in the way that you would need during an event. The best recovery drinks
actually encourage the release of insulin to stimulate maximum glycogen
rebuilding - which can reduce the amount of energy that is available in
the blood short term.
9. What problems can exist with sports beverages?
Slow to empty from the stomach
If a drink has a high % by volume of carbohydrate it will not empty rapidly.
This will be uncomfortable and will pull fluid back into the stomach.
So it will further dehydrate you. It will not give you quick benefits
of the energy it contains.
Gastro-Intestinal Problems
If a drink contains too much fructose it will be hard for the stomach
to digest and absorb it. Acid levels may also be high and can cause GI
problems. Acid is used in all non-alcoholic beverages primarily for taste
and product stability, and it has the same function in sports drinks -
but too high an acid level can be hard to absorb and can cause GI problems.
Other gastro-intestinal problems would most likely come from taking the
wrong drink at the wrong time.
Hypoglycemia
Hypoglycemia is a condition when the blood glucose levels are at seriously
low levels, taking away the body's energy - it's a medical term for bonking
or hitting the wall.
Hypoglycemia is one of the largest problems with many sports drinks. Unless
a drink is taken actually during continuous prolonged exercise, when the
insulin response to exercise is somewhat reduced, sports drinks formulated
with glucose or sugars that break down to glucose will cause an insulin
reaction - because the body will at all times attempt to maintain homeostasis,
this means (constant state of balance)
The insulin release will reduce blood sugar levels and could cause hypoglycemia
if blood sugar dips too low - lowering the amount of blood sugar available
for fueling performance. Insulin is in effect a storage hormone for glucose.
Its job is to prevent high levels of blood sugar by removing excess glucose
from the blood and promoting its storage as fat or glycogen. This is how
a high carbohydrate diet can lead to obesity. The control of insulin production
is very important.
With little or no insulin we have a condition known as Diabetes (persistent
high blood sugar levels). This leads to complications in many tissues
and needs treatment. With too much insulin secretion, or if insulin is
too effective, too much glucose is removed too fast from the circulation,
and hypoglycemia results.
10. Is it possible to drink too much?
Yes. While most runners and cyclists know the importance of hydrating,
some don't realize over-hydrating can dangerously lower blood sodium levels-a
condition known as hyponatremia.
Hyponatremia seems most common in female and beginning marathoners and
triathletes for two reasons. One, they are on the race course for many
hours, losing lots of sodium in sweat. Two, they are hypervigilant about
staying hydrated. "They drink lots of water in the days before the
race, then stop at every fluid station along the course," he says.
In a hot marathon or triathlon,
if you drink too little, you can dehydrate and risk early fatigue and
heat illness. But if you drink too much, you risk low sodium.
11. How can hyponatremia be avoided?
Keys to avoiding hyponatremia are 1) don't drink more than you sweat;
and 2) favor sports drinks, which have some sodium, over water, which
has none. Also, focus on a salty diet in the days before the race and
eat some pretzels in the last half of the race.
References:
Baumagarten, Bloebaum, Ross, et al. " Normal Human Synovial Fluid:
Osmolality and Exercise - Induced Changes" The Journal of Bone and
Joint Surgery, Decmeber 1985, V 67-A No. 9 pp 1336-1339
Link: www.gatorade.com
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