Biology Reference
In-Depth Information
meets the acceptance criteria for all parameters.
Method validation veri
The design of a study involves many steps
that need to be considered before a search for
a biomarker can be initiated. These include:
es that the optimum
analytical parameters that provide high reproduc-
ibility and accuracy have been utilized. During
routine analysis, the instrument and method
should be periodically veri
Selection of a disease.
If the selected disease is a cancer, the type
and stage should be clearly identi
ed to demonstrate
that they meet the acceptance criteria. Analytical
instrument quali
ed and
con
rmed by both a certi
ed physician and a
cation, performance quali
ca-
pathologist.
tion, and operational quali
cation were discussed
in a recent review by Clanciulli and Watzig
1
for
capillary electrophoresis and the points they
described are applicable to other types of analyt-
ical instrumentation. It is important that the exper-
iment be run at least in duplicates to insure the
reproducibility of the results, because an error in
the identi
Number of patients and controls who have
undergone a clinical examination.
Number of specimens needed to carry
a meaningful study.
The characteristics of the individuals who
provided samples for the study (e.g., age, sex,
ethnicity, etc.).
cation of a protein or metabolite
biomarker means a loss of time, effort, and
resources spent on the validation process. The
next phase in biomarker discovery is the valida-
tion of the candidate biomarker, which involves
Type of samples, such as tissue or biological
fluid and their storage history.
If using bio
uids, the type of bio
uid (e.g.,
blood, urine, saliva, etc.).
If the bio
uid is serum or plasma, type of
preservative used.
five phases, as discussed in detail by Pepe et al.,
2
Khleif et al.,
3
and Chau et al.
4
After the two phases
of discovery and validation have been reproduc-
ibly and successfully completed, a biomarker can
be moved from the laboratory to the clinic.
Whether the search is for a protein or
metabolite biomarker.
Method of sample collection, handling,
storage, and shipment.
Method of analysis (e.g., MS, NMR, etc.).
DISCUSSION
Analytical Method Validation
The search for a biomarker is not a simple
matter and involves multiple steps and different
personnel with different quali
EXPERIMENTAL DESIGN AND
EXECUTION
After the disease to study has been selected
and the samples are ready for analysis, it is
time to decide on all aspects of the experiment.
It is a good practice to have a standard operating
procedure (SOP) in place that is written specifi-
cations: a physi-
cian to con
rm the presence or absence of the
disease, a surgeon to remove the tumor, a pathol-
ogist to examine and certify the tumor type,
a technician to prepare the sample, a chemist or
biochemist to design and perform the experi-
ment, a statistician to interpret the data, and an
epidemiologist to validate the candidate protein
or metabolite biomarker in a larger population.
The selected method should be reliable, provide
accurate and reproducible results, and be
speci
-
cally for the study under consideration. The
SOP should specify the following:
Method of analysis (e.g., NMR, MS,
HPLC, GC, CE, SDS-PAGE, 2D-DIGE,
etc.).
Matrix speci
c sample preparation
c for the detection and quantitation of
the protein or metabolite biomarker.
procedure.
Extraction procedures, if necessary.
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