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Biology
Transcript of Jan14 SciMethod Helicobac
Biol 1306
1
2
Dextromethorphan
3
Dextromethorphan
4
Juice cleanse - Detox
• Thoughts on juice cleanses?
• What does “detox” mean?
• How do juice cleanses work (in the body)?
• How does the body react during a juice
cleanse?
5
BluePrint Cleanse
• BluePrintCleanse will gently rid your body of impurities, regain an
alkaline balance and normalize digestion and metabolism. Too
often, a cleanse stirs up detox symptoms that are far too intense for
the “average” person. BPC is designed for people that would like to
give their insides a rest while simultaneously going on about their
daily lives. One needn’t gamble with extremes to feel the benefits of
a cleanse.
• $65 per day
6
Hain Celestial
• Hain Celestial
– $5.7 billion market cap
– Whole Foods’ biggest supplier
• Hain Celestial bought BluePrintJuice
– For $25 million in Jan 2013
– Currently, BluePrint products bring in over
$40 million in annual revenue
7
1.4 What Is Science?
• Science is the systematic inquiry – through
observation and experiment – into the
origins, structure, and behavior of living
and nonliving environments
1.4 What Is Science?
• Science is based on the principle that all
events have natural causes
– The belief that all events can be traced to
natural causes that we can comprehend
(natural causality)
1.4 What Is Science?
• The scientific method is an important tool of
scientific inquiry
– The scientific method consists of six interrelated
elements
• Observation
• Question
• Hypothesis
• Prediction
• Experiment
• Conclusion
1.4 What Is Science?
• The six steps of scientific inquiry
1. Observation of a specific phenomenon
2. The observation, in turn, leads to a question
3. The question leads to formulation of a
hypothesis, based on previous
observations, which is offered as an answer
to the question
1.4 What Is Science?
• The six steps of scientific inquiry (continued)
4. The hypothesis leads to a prediction, which is
the expected outcome of testing if the hypothesis is
correct
5. The prediction is tested by carefully designed
additional observations or carefully controlled
manipulations called experiments
6. The experiments produce results that either support
or refute the hypothesis, allowing the development
of a conclusion
1.4 What Is Science?
• Biologists test hypotheses using controlled
experiments
– Two types of situations are established
• A baseline or control situation in which all possible
variables are held at a constant
• An experimental situation in which one factor, variable,
is manipulated to test the hypothesis to determine
that this variable is the cause of an observation
– Science is useless unless communicated
1.4 What Is Science?
• Scientific theories have been thoroughly tested
– A scientific theory is a general and reliable
explanation of important natural phenomena that has
been developed through extensive and reproducible
observations and experiments
15
Ulcers
A Case Study in the
Scientific Method
Ulcers
16
17
CQ1: What do you think causes
ulcers?
A: Stress.
B: Excessive stomach acids.
C: Bacteria.
D: A bad diet and alcohol use.
E: Being overweight.
18
What Causes Ulcers?
Design an experiment to test if the “excess
acid hypothesis” is true.
In your small groups, design the
experiment. Remember, be specific about
how you would treat your groups and what
you would measure!
19
CQ2: Which is a good way to test the
“excess acid hypothesis”?
A: Examine ulcer patients of a range of ages and measure their stomach acid levels.
B: Have volunteers drink alcohol and measure their stomach acid levels.
C: Lower stomach acid levels of some volunteers (using drugs/antacids), and measure numbers of ulcers in all volunteers.
D: Examine patients of a range of ages and measure the number of ulcers in each person.
E: Put volunteers through a stress test and then measure their stomach acid levels.
20
CQ3: What step in the scientific
method does this test represent?
A: Making observations.
B: Developing a hypothesis.
C: Determining predictions.
D: Testing a hypothesis.
E: Assessing support for a hypothesis.
21
A Possible Study Design
• Doctors divide patients into two groups:
• After 3 months, the number of ulcers per patient is assessed.
• Predict what the results would look like if the excess acid theory was supported.
Group 1 received antacids and
were instructed to take them
3x/day
Group 2 received sugar pills
and were instructed to take
them 3x/day
22
Group 1 Group 2
Treatment Group
# U
lcers
/ pa
tien
t
Draw this graph: Predict what the results would
look like if the “excess acid theory” was supported
by the results of this study:
23
CQ4: Which graph most closely matches
the results you predicted?
Group 1 Group 2
Treatment Group
Group 1 Group 2
Treatment Group
Group 1 Group 2
Treatment Group
Group 1 Group 2
Treatment Group
# U
lcers
/ patient
# U
lcers
/ patient
# U
lcers
/ patient
# U
lcers
/ patient
A
C D
B
24
• Unfortunately, this type of controlled experiment was NOT conducted.
• BUT, patients who took antacids had decreased ulcer symptoms.
• If the patients stopped taking the antacids their ulcers returned.
Image by: Midnightcomm
25
Dr. J. Robin Warren: (pathologist)
Examines stomach
biopsies of patients
with various stomach
ailments.
26
CQ5: The slides that Dr. Warren examined had
smudges that were not clearly visible under low
power, so he attached a high-power lens to his
microscope. What do you think he was able to
see then?
A: Many cells at once.
B: Only one cell at a
time.
C: Organelles within the
cells.
D: Bacteria.
E: Viruses .
LOW
POWER
27
Dr. Warren thought he saw:
• Helicobacter pylori (a new species of bacteria)
• But no one else believed him!
The black squiggly spots on the slide
are bacteria that Dr. Warren observed
In his biopsy slides.
28
CQ6: Dr. Warren’s colleagues did not believe
there were bacteria in the stomach. Why do you
think other pathologists did not believe bacteria
were in the stomach biopsies?
A: Bacteria are never found inside the human body.
B: The pH of the stomach is too acidic for any bacteria to survive.
D: Ulcers and stomach cancer are caused by age, stress and diet – bacteria have nothing to do with the problems the patients came to the hospital for.
29
So, Dr. Warren:
• Used a special stain
that highlights
bacteria on his
slides.
• This convinced his
colleagues that the
bacteria were there.
30
Talk to your neighbor
• Dr. Warren thinks H. pylori causes
ulcers.
• What is another hypothesis to explain
why Dr. Warren was finding bacteria on
his slides? (there are at least three
alternative hypotheses...)
31
Alternative explanations
(hypotheses):
1. The biopsy specimens were contaminated AFTER samples were taken from the patients.
2. The bacteria live in the stomach, but do no damage.
3. The bacteria are an opportunistic species that arrives AFTER ulcers have already weakened the stomach’s defenses.
32
Dr. Barry J. Marshall Joins Dr.
Warren’s Research
• Hypothesis: Bacteria CAUSE stomach ulcers.
• If you were working with Drs. Warren & Marshall to design a study to determine whether the bacteria caused ulcers, how would you do it?
33
Their First Survey Study: • 100 stomach ulcer patients surveyed
(biopsy taken).
• 100% had H. pylori present.
34
CQ7: The doctors treated ulcer patients
with antibiotics to see if the disease
stopped. What is missing from their study?
A: An experimental treatment.
B: A control group.
C: An independent variable.
D: A dependent variable.
E: A hypothesis.
35
Important Aspects of
Experimental Design
• Testable hypothesis, i.e., a way to measure a
response and a way to divide groups up into:
• Control and Treatment Groups
– Control is group that does not get the
hypothesized treatment.
– Treatment is group that does get the
hypothesized treatment.
36
The Importance of Controls
Why do we need controls? Explain to
your neighbor …
37
If they set up their antibiotic study with a treatment
group receiving antibiotics and a control group
receiving a placebo (no antibiotics), what results
would you expect if the original “excess acid
hypothesis” was supported?
Control Experimental
Num
ber
of ulc
ers
aft
er
2 m
onth
s
38
CQ8: What results would you expect if the old
“excess acid hypothesis” were supported? N
um
ber
of ulc
ers
aft
er
2 m
onth
s
Num
ber
of ulc
ers
aft
er
2 m
onth
s
Num
ber
of ulc
ers
aft
er
2 m
onth
s
Nu
mb
er
of ulc
ers
aft
er
2 m
onth
s
Con Exptl
Con Exptl Con Exptl
Con Exptl
A B
C D
39
What results would you expect if Drs.
Warren and Marshall’s “bacteria cause
ulcers” hypothesis is supported?
Control Experimental
Num
ber
of ulc
ers
aft
er
2 m
onth
s
40
CQ9: What results would you expect if the “bacteria
cause ulcers hypothesis” were supported? N
um
ber
of ulc
ers
aft
er
2 m
onth
s
Num
ber
of ulc
ers
aft
er
2 m
onth
s
Num
ber
of ulc
ers
aft
er
2 m
onth
s
Nu
mb
er
of ulc
ers
aft
er
2 m
onth
s
Con Exptl
Con Exptl Con Exptl
Con Exptl
A B
A D
C
41
Actual Results of Warren &
Marshall’s Study
• When treated with antibiotics, 80% of patients were permanently cured of their ulcers.
• To further demonstrate the cause and effect relationship, Dr. Marshall (who did NOT suffer from ulcers), swallowed a flask of H. pylori from the lab. – Within a week he was suffering from symptoms of
gastritis and had H. pylori populations in his stomach!
– He cured himself with an antibiotic treatment.
42
CQ11: If you were shown the results of the
Warren & Marshall antibiotic study, you
would conclude:
A: The excess acid hypothesis is supported and is the best explanation for the causation of ulcers.
B: The bacteria cause ulcers hypothesis is supported and is the best explanation for the causation of ulcers.
C: The excess acid hypothesis has not been overturned, but bacteria might have something to do with ulcers.
D: This study supports the bacteria cause ulcers hypothesis, but I need more evidence.
43
EPILOGUE
44
Medical doctors worldwide were
NOT easily convinced
• Drs. Warren and Marshall had trouble getting their results published in scientific journals and presenting results at scientific meetings.
• It took over 15 years and many more studies from researchers all over the world, before the “bacteria cause ulcers” hypothesis was accepted by the medical community.
45
Drs. Warren & Marshall win the 2005
Nobel Prize in Medicine & Physiology
The Nobel Prize committee recognized
Warren & Marshall’s work changed peptic
ulcers from one of the world’s most
common chronic, debilitating diseases to
one easily cured with a simple drug
regimen.
Opened new avenues of research -
microbial causes of other chronic
inflammatory diseases.
Also increased understanding of links
between chronic infection, inflammation,
and cancer.
