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CASE FILES: BIOCHEMISTRY
regarding methods of diagnosis and treatment. Otherwise, our attempts
are only
empiric,
in other words, only by trial and error and observation
of association. Students are encouraged to think about the mechanisms
and underlying cause rather than just memorizing by rote. For example,
in sickle cell disease, students should connect the various facts together,
setting the foundation for understanding disease throughout their life:
In sickle cell disease, valine (a hydrophobic amino acid) is substi-
tuted for glutamate (a charged, hydrophilic amino acid) in the sixth
position in the P-globin chain of hemoglobin (Hb). This decreases the
solubility of hemoglobin when it is in the deoxygenated state, resulting
in its precipitation into elongated fibers in the red blood cell.
This causes the red blood cell to have less distensibility and thus to
sickle,
leading to rupture of the red blood cell (hemolysis) and block-
age in small capillaries. The
sludging
in small capillaries leads to poor
oxygen delivery, ischemia, and pain.
2.
Which biochemical marker will be affected by therapy?
After a diagnosis has been made and therapy initiated, then the
patient response should be monitored to assure improvement. Ideally,
the patient response should be obtained in a scientific manner: unbi-
ased, precise, and consistent. Although more than one physician or
nurse may be measuring the response, it should be as carefully per-
formed with little inter- (one person to the next) or intravariation (one
person measuring) as possible. One of the therapeutic measures
includes serum or imaging markers; for example, in diabetic ketoaci-
dosis, the serum glucose and pH would be measured to confirm
improvement with therapy. Another example would be to follow the
volume of a pulmonary mass imaged by CT scan after chemotherapy.
The student must know enough about the disease process to know
which marker to measure and the expected response over time.
3.
Looking at graphical data, what is the most likely biochemical
explanation for the results?
Medicine is art and science. The
art
aspect consists of the way that the
physician deals with the human aspect of the patient, expressing empathy,
compassion, establishing a therapeutic relationship, and dealing with
uncertainty; the
science
is the attempts to understand disease processes,
making rational treatment plans, and being objective in observations. The
physician as scientist must be precise about how to elicit data and then
carefully make sense of the information, using up-to-date evidence.
Exercises to develop the skills of data analysis require interpretation of
data in various representations, such as in tables or on graphs.
4.
Based on the DNA sequence, what amino acid or protein would be
produced, and how would the protein be manifested in a clinical
setting?
The clinician-basic scientist collaboration requires each party to
“speak the same language” and translate forward and backward from
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