Sample Laboratory Activity:
Title: Characterization of the Glycemic Response to a High Fiber-Lower Calorie
Sweetened Dried Cranberry Snack.
Introduction: When a snack is consumed the sugars in it are absorbed by the small intestine and accumulate in the blood
postprandially. The blood carries the glucose to the rest of the body where sugars are converted to energy (oxidation to CO 2 and ATP)
or stored as glycogen for use later. Insulin-sensitive cells in your body, such as skeletal myocytes and adipocytes, require that a
hormone (insulin) be present before the glucose in the blood can be absorbed and utilized. If insulin is not released into the blood by
the Beta-cells of the pancreas, then glucose has no place to go and it remains in the blood. Some drugs help diabetics improve the
sensitivity of their tissues to insulin or improve the ability of the pancreas to release insulin in response to high blood glucose.
Phenolic compounds in foods have also been suggested to have a similar effect on insulin sensitivity and release.
Hyperglycemia and hyperinsulinemia are cardinal signs of diabetes and associated with its pathology. High levels of glucose in the
blood (hyperglycemia) can lead to glycouria and kidney failure, furthermore glycosylation of hemoglobin and other proteins
associated with promotion of coronary heart disease.
Hyperinsulinemia is a central sign of insulin resistance and is associated with excessive growth of blood vessels within the retina that
lead to blindness for many diabetics. Hyperglycemia is also associated with a reduction in plasma antioxidant vitamins and an increase
in oxidative injury to DNA, proteins and the low density lipoproteins within diabetics.
Cranberries and products derived from cranberries that include cranberry juice and sweetened dried cranberries (such as the popular
Ocean Spray product Craisins®) may also help protect people, especially diabetics from coronary heart disease (Maher et al 2000),
urinary tract infections (Avorn et al 1994) and oxidative disorders (Wilson et al 1999). Phenolic compounds produced in the
cranberry fruit (anthocyanidins) may be associated with a reduction in blood glucose following a meal (Wilson et al 2007) by slowing
intestinal glucose absorption or improving insulin sensitivity. It has also been suggest that foods that are rich in fiber may also slow
digestion and reduce carbohydrate absorption from the intestine. Polydextrose is a food additive that can be used to raise the fiber
content of a food and may affect glucose and insulin metabolism in this regard.
Plants create different phenolic compounds (chemicals) for a variety of purposes. Phenolics compounds are responsible for
photosynthesis, all variety of leaf colors, pleasant tastes that make us want to eat some plants and less pleasant tastes that make us
avoid some fruits until they are ripe. Phenolics are may also help explain why it persons consuming the greatest amount of phenolicrich plant foods experience the lowest incidence of mortality from cardiovascular disease. They may also explain why persons
consuming large amounts of fruits and vegetables tend to have a reduced incidence of diabetes.
Consumption of a snack food is one way, along with glycogen catabolism, is one way we maintain blood glucose at safe levels.
Development of a snack that would slow carbohydrate absorption from the intestine and improve insulin sensitivity would be useful
for diabetics because it could prevent deleterious blood glucose and plasma insulin concentrations. Cranberries are naturally rich in
fiber and anthocyanidins that may make it a good snack choice for diabetics. This laboratory activity will help determine if a fiberenriched sweetened dried cranberry provides nutritional benefits that may make is a good snack for diabetics. While it might be useful
to try this with diabetics, it is best to first try this with a healthy population whose glucose and insulin metabolism is regular, prior to
future studies with a population that has many additional health complications that would need consideration as part of an
experimental design.
Nutritional Problem We Want to Examine: Is a high fiber lower calorie sweetened dried cranberry a better snack choice than
other comparable alternatives?
The Four Treatments Used in this Experiment
1) White bread (57g; 160 Cal; 1 g fiber)
2) Raisins (RC; 40 g; 130Cal; 1 g fiber)
3) Sweetened Dried Cranberries (40g, 138 Cal; 2.1g fiber)
4) Sweetened Dried Cranberries with less sugar and added fiber (40g; 113 Cal; 1.8g fiber + 10g polydextrose)
This lab will examine THREE SIMPLE QUESTIONS and HYPOTHESES:
1) Are all snacks alike with respect to one’s metabolic response? What is YOUR group hypothesis in this regard?
2) How long does it take for blood glucose and plasma insulin to reach their peak and return to normal following a snack?
What is YOUR group hypothesis in this regard?
3) Are Sweetened Dried Cranberries with less sugar and added fiber a good choice as a snack? What is YOUR group
hypothesis in this regard?
Your mission in this laboratory exercise will be to have one volunteer from your group consume the assigned snack and collect the
timed blood samples from your volunteer. You will be analyzing the blood samples you collect during this laboratory exercise, as
well as providing samples for your plasma insulin to be analyzed. All members of the group must assist the test volunteer with the
analyses.
Your group will need to arrive at the lab early and on on a special day. All testing will occur on Tuesday, Wednesday or Thursday
morning (April 14, 15 or 16th) with an arrival time between 5 am and 8am and a finish time between 8 and 11am. A special signup
sheet will be provided. The early test time ensures that testing can occur on a nempty stomach (i.e. if your lab normally started at 4pm
you would not have been able to eat after dinner the night before). Contact Drs. Wilson/Ragsdale if any group member fails to
show-up for your lab time or fails to participate in preparing the lab write-up.
It is quite important that the volunteer DOES NOT EAT OR DRINK anything from 8 pm the night before the experiment until the
experiment is completed (except for the test food you will consumer on the following morning). Fasting like this can be difficult,
BUT IS CRITICAL for the experiment to function properly. In addition, your volunteer cannot exercise or work out prior to
coming to lab for during the experiment. Your group volunteer will be assigned by the Instructor to one of the four experimental
groups when you arrive at the laboratory to begin the experiment.
All members need not be in lab for entire 3 hours, between sample times you can go to class, hangout in the hall way and study, take a
nap, but you cannot go to the gym and “work out” because this would affect blood glucose levels. You DO need to be in the AP lab to
collect your samples at the 0, 30, 60, 120 and 180 minute times. If a member of your 3-4 person group absolutely cannot make it to lab
due to a class lecture conflict, it is ok for the other group members to cover for them while they are gone. Perhaps the other group
members will let the absent person do extra work on the lab write-up to make up for the absence. The volunteer needs to be at AP lab
at the 0-, 30-, 60-, 120-, and 180-minutes samples times, so if they have class conflicts the group will need to find a new volunteer.
Remember to be in the lab 15 to 20 minutes prior to the start time to get organized! Safe with blood: USE GLOVES AT ALL
TIMES! WASH HANDS WHEN DONE!
Blood Analysis:
Review methods for collecting blood with a finger prick and for determining the hematocrit and safety considerations mentioned in
Blood Lab your performed back in January and at end of this lab! Record Data on Sheets: You keep one sheet…..You hand other
sheet in when done (5pts)
Blood Glucose Measurement Protocol with an Accu-Check Analyzer:
Finger prick and blood analysis is to be completed at 0-minutes (experiment starts when 0-minute blood collection has been
completed), 30-minutes, 60-minutes, 120-minutes, and 180-minutes after the start of the experiment.
Put on gloves and keep all materials at the station next to the window. At the station you will use a Unistik 2 to draw blood from
the finger.
1) Wipe lateral edge of finger with alcohol swab.
2) Let it dry before drawing blood (it hurts if alcohol has not dried off)
3) Follow instructions in illustrations below:
PLACE UNISTIK FIRMLY AGAINST FINGER PRIOR
TO RELEASING THE FIRE BUTTON, it will make a click sound and the lancet will strike finger then retract.
4) Immediately throw Unistik in “Sharps Container” after use… DO NOT REUSE!
5) Put finger below level of heart and let a drop of blood form,,,,,you may “GENTLY” milk blood out if you need to until a large drop
is present.
6) Blood Glucose Measurement Protocol with an Accu-Check Analyzer:
a) Insert test strip into slot at rounded face of analyzer, with analyzer sitting flat on bench. Insert with metal strips UP and
INTO slot.
b) Analyzer will “beep” and a LCD image of a drop of blood will then appear when it is ready.
c) Dangle this drop over and touch it into the “yellow” analysis box of the test-strip. Be sure the entire “box” is filled with a
large drop of blood and that No Tan color remains. If you can still see “tan” color, add a bit more blood to the test strip. You
have 10 seconds to complete the filling of the box prior to needing a new test strip!
d) The LCD image of a clock will blink for 30-90 seconds and a “beep” will precede the display of the glucose concentration
of the sample in mg glucose/dL. Record data on sheet!
7) Fill TWO Heparinized Hematocrit Tubes with additional blood from the finger for Insulin Analysis:
a) As soon as the drop of blood has been added to the glucose-test strip, fill TWO heparinized (red) hematocrit tubes and seal
the blood end with critoseal. If necessary, you may gently squeeze “milk” the finger. Be sure the first tube is about 2/3 filled
before trying to fill the second tube about 2/3 of the way.
b) Take the two hematocrit tubes to the two Biology Students and identify your group name and sample time.
d) A group of Biology Majors will perform an insulin assay on the plasma portion of the blood in this hematocrit tube.
This will take about one week to complete.
8) Wipe finger with a KimWipe and clean up supplies at your station.
Be Safe with blood: USE GLOVES AT ALL TIMES! WASH HANDS WHEN DONE!
References Cited:
Avorn J, Monane M, Gurwitz JH, Glynn RJ, Choodnovskiy I, Lipsitz LA. Reduction of bacteriuria and pyruria after ingestion of
cranberry juice. JAMA 1994;271:751-754.
Wilson T, Meyers SL, Singh AP, Vorsa V. Favorable Glycemic Response of Type 2 Diabetics to Low Calorie Cranberry Juice.
Journal of Food Science. 2008, 73:H241-245.
Wilson T, Singh AP, Vorsa N, Goettl CD, Kittleson KM, Roe CM, Kastello GM, Ragsdale FR: Human Glycemic Response and
Phenolic Content of Unsweetened Cranberry Juice. J Med Food. 2008; 11:46-54.
Maher MA, Mataczynski H, Stephaniak HM, Wilson T. Cranberry juice induces nitric oxide dependent vasodilation and transiently
reduces blood pressure in conscious and anaesthetized rats. J. Medicinal Foods. 2000; 3:141-147.
Wilson T, Porcari JP, Maher MA. Cranberry juice inhibits metal- and non-metal initiated oxidation of low density lipoprotein. J. Nutra.
Funct. Med. Foods. 1999; 2:5-14.
Laboratory Write-up: 20 points (5 pts extra credit for exceptionally nice write-ups)
What will you need to write up as a group for this laboratory exercise?
You will compare the data collected from your anonymous volunteer with the average data collected for the members of the
four different treatment groups. This data will be available approximately 1 week after the lab has been completed at Dr.
Wilson’s website.
Title Page: Lab Title, Your Name, Your Lab Time and Your group Assignment
Introduction: About of 100-200 words that describes the basics of the experiment (including a one or two line summary of the
findings).
Methods: About of 100-200 words that describes what you did in the experiment and “HOW” you did it. You also explain where you
down loaded the measurements taken from your “volunteer”. You should also describe (age, wt, sex, but NO Names) of your
volunteer and the average volunteer used by the other groups. To maintain volunteer anonymity at no time should you give the
name of any volunteer.
Results: (Length is variable; data tables look really nice). In the results section you describe the response of the volunteer from your
group. You also describe the results of the other groups (these results will be down-loaded from the A and P laboratories website.
Describing results means using means or other statistical measures to illustrate your findings.
Discussion: In this section you need to address several things (6 separate sections of at least one paragraph each). This is where you
discuss your findings.
1) Address whether you think the data you collected from your volunteer was valid. How well did your group follow instructions? (1
paragraph)
2) Address whether your volunteer’s results were the same as, or different from, others assigned to the same treatment. ? (1 paragraph)
3-5) Address each of the three hypotheses mentioned earlier (1 paragraph each). Did the data from all the group support of disprove
each of your hypotheses?
6) What did your experiment mean? Did you prove/disprove your hypotheses? Why or Why not? (1 paragraph)
References Cited: You will need to use at least three references in this laboratory write-up: One webpage, One book, and One peerreviewed journal reference collected from PubMed/Medline/Science Direct (See search engines at WSU library webpage or
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi). If all three of your sources are from peer-reviewed journals your report will look
“Even Better” . Yes you are welcome to use more than three sources.
You need to be sure that each source is used in this paper somewhere and cited in the paper. Put the reference source immediately
after where the fact is used in your paper. For example: “In our experiment, the blood glucose of our female volunteer started at 80
mg/dl and following bread consumption it increased to 140 mg/dl after 30 minutes and returned to 104 mg/dl 120 minutes later. The
normal female blood glucose is 100 mg/dl (Saladin 2003). We believe that the blood glucose increased because glucose was absorbed
fro mteh bread and decreased because insulin was released from the pancreas.” This explains your observation to the reader and lets
the reader know what facts came from what sources. It also lets the reader ask if your facts sound believable. All of your sources
need to be used in the text of your write-up at some point in your write-up.
Caution About Exposure to Pathogens in this Laboratory Activity: BE CAREFUL AND BE SAFE! Like all other body fluids,
blood can house viruses and bacterial agents -- pathogens that can cause disease. AIDS (HIV) and Hepatitis are just two examples of
such contaminants that you are probably familiar with. You need not worry about exposure to these contaminants from your own
blood -- you are already exposed. But you must be much more diligent when working with the fluids from someone else. There are a
few precautions that must be taken when working with the body fluids from someone else. You must wear gloves. Do not assume a
sample is disease-free, instead assume it is contaminated. Do not re-use any lancet, needle or object that has been exposed to the
blood sample. All products contaminated with blood must be disposed of in the appropriate containers. For example, the lancets
must be disposed of in the red Sharpee container. All paper towels with blood must be placed in the dishpan labeled such. All
hematocrit tubes must be considered sharp objects and should be placed in the Sharpee container. Used gloves should be disposed of
in these pans as well.
You will be pricking your finger and collecting your blood. If you already know that you cannot do this, you will not be forced to
participate. Data from the experiment will be available for everyone to analyze. If you can collect your own blood, attempt to do so.
If at anytime during the course of the lab you feel dizzy, faint or if your lab partner notices that you are "very absent minded", contact
your lab instructor and then sit down on the floor. Do not attempt to leave the classroom. If you are about to faint and attempt to
leave the class, you may make it past your desk, into the front of the room or into the middle of the hallway. In any of these cases,
your lab instructor will be all over you for not following instructions, once they determine you are OK. And you will be escorted to
the health center for complete evaluation. The easiest way to minimize the risk to your body, if you do faint, is to minimize the
distance your body must travel to reach the floor. That is why you are asked to sit down. It is partly the responsibility of the lab
partners to help monitor this situation. Everyone needs to talk to the blood donor and make sure that they are "in the moment" and
responding to your discussion. This is part of that personal touch, that compassion and caring the health care profession relies on.
Glycemic Response to a Snack Raw Data Recording Sheet: “Group Copy”
Volunteer Weight:______lbs; Height:______inches; Age:______years; Sex: Male or Female
Your Team Name:_____________________ Team Treatment Assignment:_________________
What is the Day and Time you are performing this lab activity (see sign-up chart):
Date:__________Day:________Time to Start:___________Time to Finish:___________
Remember to be in the lab 15 to 20 minutes prior to the start time to get organized!
At what times in the day will you collect your small blood samples?
0min-_______ 30min-________ 60min-_______ 120min-________180min-______
0-Minutes: Immediately after this data is recorded your subject can eat their snack treatment (group #1 receives nothing during
the experimental period) and the experiment has begun.
What was your subjects blood pressure and heart rate?_____________________
What time does clock say?___________ What is your subjects blood glucose?_____________________mg/dL
What is your subjects plasma insulin?_______%
Comments:__________________________________________________________________________________________________
_______________________________________________
30-Minutes: Clock Time:_____________ (do not measure plasma insulin)
What is your subjects blood glucose?______________mg/dL What is your subjects plasma insulin?_______
Comments:__________________________________________________________________________________________________
_______________________________________________
60-Minutes: Clock Time:_____________
What was your subjects blood pressure and heart rate?_____________________
What is your subjects blood glucose?______________mg/dL What is your subjects plasma insulin?_______
Comments:____________________________________________________________________________________ 120-Minutes:
Clock Time:_____________
What was your subjects blood pressure and heart rate?______________
What is your subjects blood glucose?______________mg/dL What is your subjects plasma insulin?_______
Comments:____________________________________________________________________________________
180-Minutes: Clock Time:_____________
What was your subjects blood pressure and heart rate?_____________
What is your subjects blood glucose?_____________mg/dL What is your subjects plasma insulin?____________
Comments:____________________________________________________________________________________
Glycemic Response to a Snack Raw Data Recording Sheet: “Group Copy”
Volunteer Weight:______lbs; Height:______inches; Age:______years; Sex: Male or Female
Your Team Name:_____________________ Team Treatment Assignment:_________________
What is the Day and Time you are performing this lab activity (see sign-up chart):
Date:__________Day:________Time to Start:___________Time to Finish:___________
Remember to be in the lab 15 to 20 minutes prior to the start time to get organized!
At what times in the day will you collect your small blood samples?
0min-_______ 30min-________ 60min-_______ 120min-________180min-______
0-Minutes: Immediately after this data is recorded your subject can eat their snack treatment (group #1 receives nothing during
the experimental period) and the experiment has begun.
What was your subjects blood pressure and heart rate?_____________________
What time does clock say?___________ What is your subjects blood glucose?_____________________mg/dL
What is your subjects plasma insulin?_______%
Comments:__________________________________________________________________________________________________
_______________________________________________
30-Minutes: Clock Time:_____________ (do not measure plasma insulin)
What is your subjects blood glucose?______________mg/dL What is your subjects plasma insulin?_______
Comments:__________________________________________________________________________________________________
_______________________________________________
60-Minutes: Clock Time:_____________
What was your subjects blood pressure and heart rate?_____________________
What is your subjects blood glucose?______________mg/dL What is your subjects plasma insulin?_______
Comments:____________________________________________________________________________________ 120-Minutes:
Clock Time:_____________
What was your subjects blood pressure and heart rate?______________
What is your subjects blood glucose?______________mg/dL What is your subjects plasma insulin?_______
Comments:____________________________________________________________________________________
180-Minutes: Clock Time:_____________
What was your subjects blood pressure and heart rate?_____________
What is your subjects blood glucose?_____________mg/dL What is your subjects plasma insulin?____________
Comments:____________________________________________________________________________________
Cranberry Laboratory Write-up: 20 points
(An additional 5 points extra credit for exceptionally well written reports)
Title Page: Lab Title, Team Name, Lab Time and Group Assignment
1 pt____:
Title Page items above.
Introduction: About ½ page or 100-200 words that describes the basics of the experiment (including a one or two line summary of
the findings).
1pt_____:
Title, Names, Lab times, group assignment etc.
2pt_____:
Length-100 words minimum or more that discuss the basics of the Experiment you performed.
1pt_____:
You need to include 1-2 sentences about what the experiment determined (either the results of their own
participant or results of the entire class), more is better but not needed.
About ½ page (100-200 words) that describes what you did in the experiment and “HOW” you did it. To maintain
volunteer anonymity at no time should you give the name of any volunteer.
2pt_____:
Length-100 words minimum or more.
1pt_____:
Explanation of how experiment was performed on at least their participant.
Methods:
Results:
In the results section you describe the response of the volunteer in relation to all treatments. Describing results
means using statistical measures to illustrate your findings.
2pt_____:
Discussion:
This is where you discuss your findings.
2pt____
Address whether you think the data you collected from your volunteer was valid. How well did your group
follow instructions, etc? (1 paragraph)
2pt____
Address whether your volunteer’s results were the same as, or different from, others assigned to the same
treatment? This is pretty important, so please don’t neglect this. (1 paragraph)
2 pt____
Did you have a hypothesis for what each treatment (Nothing, White Bread, Sweetened-dried cranberries,
low sugar SDC and raisins would do?
2pt_____
What did your experiment mean? Did you prove/disprove your hypotheses? Why or Why not? (1
paragraph)
2pt_____
References Cited: You will need to use at least three references in this laboratory write-up: At least
one of which needs to be a peer-reviewed journal reference collected from PubMed/Medline/Science Direct (See search
engines at WSU library webpage or http://www.ncbi.nlm.nih.gov/entrez/query.fcgi).