Clinical Biochemistry Exam 2
questions and answers latest
top score.
epitope CORRECT ANSWER.An Ab molecule is an immunoglobulin (Ig) with a
functional domain known as F(ab); this area of the Ig protein binds to a
site on the Ag. An Ag is relatively large and complex and usually has
multiple sites that can bind to antibodies (Abs) with different specificities;
each site on the Ag is referred to as an antigenic determinant or
hapten CORRECT ANSWER.small molecule that has to bind to a larger molecule
to form an antigen
The affinity for the Hp is related to the likelihood to bind or to the degree of
complementary nature of each
Affinity CORRECT ANSWER.is the tendency of a chemical species such as an
atom or molecule to react with another to form a chemical compound
avidity CORRECT ANSWER.refers to the accumulated strength of multiple
affinities of individual non-covalent binding interactions
likely hood of separation
cross-reactivity CORRECT ANSWER.an Ab can react with an Ag that is
structurally similar to the homologous Ag
radial immunodiffusion (RID) CORRECT ANSWER.is an immune precipitation
method used to quantitate protein (the Ag).
,In this method, monospecific antiserum is added to the liquefied agarose;
then, the agarose is poured into a plate and cooled.
Wells are cut into the solidified agarose. Multiple standards, one or more
quality control samples, and patient samples are added to the wells.
The Ag diffuses from the well in all directions, binds to the soluble Ab in
the agarose, and forms a complex seen as a concentric precipitin ring.
The diameter of the ring is related to the concentration of the Ag that
diffused from the well. A standard curve is constructed to determine the
concentration in the quality control and patient samples.
The usable analytic range is between the lowest and highest standards. If
the ring is greater than the highest standard, the sample should be diluted
and retested. If the ring is less than the lowest standard, the sample should
be run on a low-level plate. Two variations exist: the endpoint (Mancini)
method and the kinetic (Fahey-McKelvey) method.
Ouchterlony technique CORRECT ANSWER.The simplest and least sensitive
method is double diffusion.
Agarose is placed on a solid surface and allowed to solidify. Wells are cut
into the agarose. A common template is six Ab wells, surrounding a single Ag
well in the center. Soluble Ag and soluble Ab are added to separate wells and
diffusion occurs. The intensity and pattern of the precipitation band are
interpreted.
The precipitin band of an unknown sample is compared with the precipitin
band of a sample known to contain the Ab. A pattern of identity confirms the
presence of the Ab in the unknown sample. Patterns of partial identity and
nonidentity are ambiguous.
This technique can be used to detect Abs associated with autoimmune
diseases, such as Sm and ribonucleoprotein detected in systemic lupus
erythematosus, SSA and SSB in Sjögren's syndrome, and Scl-70 in
progressive systemic sclerosis. However, most of these Abs are also
detected using enzyme-linked immunoassays or multiplex bead array
systems (e.g., Luminex Corp).
Fluorescence polarization immunoassay (FPIA) CORRECT ANSWER.is another
assay that uses a fluorescent label
This homogenous immunoassay uses polarized light to excite the
fluorescent label. Polarized light is created when light passes through
special filters and consists of parallel light waves oriented in one plane.
When polarized light is used to excite a fluorescent label, the emitted light
could be polarized or depolarized. Small molecules, such as free fluorescent-
labeled Hp, rotate rapidly and randomly, interrupting the polarized light.
,Larger 3molecules, 3such 3as 3those 3created 3when 3the 3fluorescent-labeled 3Hp
3binds 3to 3an 3Ab, 3rotate 3more 3slowly 3and 3emit 3polarized 3light 3parallel 3to 3the
3excitation 3polarized 3light.
The 3polarized 3light 3is 3measured 3at 3a 390° 3angle 3compared 3with 3the 3path 3of
3the 3excitation 3light. 3In 3a 3competitive 3FPIA, 3fluorescent-labeled 3Hp 3and
3unlabeled 3Hp 3in 3the 3sample 3compete 3for 3limited 3Ab 3sites.
When 3no 3unlabeled 3Hp 3is 3present, 3the 3labeled 3Hp 3binds 3maximally 3to 3the
3Ab, 3creating 3large 3complexes 3that 3rotate 3slowly 3and 3emit 3a 3high 3level 3of
3polarized 3light.
When 3Hp 3is 3present, 3it 3competes 3with 3the 3labeled 3Hp 3for 3the 3Ab 3sites; 3as
3the 3Hp 3concentration 3increases, 3more 3labeled 3Hp 3is 3displaced 3and 3is 3free.
3The 3free 3labeled 3Hp 3rotates 3rapidly 3and 3emits 3less 3polarized 3light. 3The
3degree 3of 3labeled 3Hp 3displacement 3is 3inversely 3related 3to 3the 3amount 3of
3unlabeled 3Hp 3present
Microparticle 3capture 3enzyme 3immunoassay 3(MEIA) 3CORRECT 3ANSWER.is 3an
3automated 3assay 3available 3on 3the 3AxSYM 3Analyzer 3(Abbott 3Laboratories).
3The 3microparticles 3serve 3as 3the 3solid 3phase, 3and 3a 3glass 3fiber 3matrix
3separates 3the 3bound 3labeled 3reagent.
Both 3competitive 3and 3noncompetitive 3assays 3are 3available. 3Although 3the
3label 3is 3an 3enzyme 3(ALP), 3the 3substrate 3(4-methylumbelliferyl 3phosphate) 3is
3fluorogenic.
Point-of-care 3testing 3(POCT) 3CORRECT 3ANSWER.is 3defined 3as 3"those 3analytical
3patient- 3testing 3activities 3provided 3within 3the 3institution, 3but 3performed
3outside 3the 3physical 3facilities 3of 3the 3clinical 3laboratories.
These 3include 3tests 3for 3electrolytes, 3glucose, 3hemoglobin 3A1c, 3urinalysis,
3pregnancy, 3drugs 3of 3abuse, 3therapeutic 3drug 3monitoring, 3occult 3blood,
3blood 3gases, 3coagulation 3tests, 3enzymes, 3and 3cardiac 3markers. 3POCT 3is
3also 3available 3for 3infectious 3diseases 3such 3as 3HIV, 3gonorrhea, 3syphilis,
3streptococcus, 3influenza, 3fungal 3infections, 3and 3tuberculosis
POCT 3offers 3several 3advantages 3compared 3with 3central 3laboratory 3testing.
3The 3major 3advantage 3of 3POCT 3is 3faster 3delivery 3of 3results. 3POCT 3is
3designed 3to 3work 3with 3the 3flow 3of 3patient 3management 3and 3care, 3allowing
3physicians 3to 3order 3and 3perform 3the 3test 3and 3immediately 3make 3a 3medical
3decision
Portability 3of 3POCT 3allows 3for 3increased 3access 3to 3testing 3in 3a 3wider 3variety
3of 3sites, 3for 3example, 3rural 3areas, 3accident 3sites, 3areas 3with 3limited
3infrastructure 3and 3personnel, 3and 3locations 3with 3underserved 3populations
Comparing 3POCT 3to 3Lab 3Testing 3CORRECT 3ANSWER.Advantages
- convenience 3for 3both 3the 3attending 3physician/nurse 3and 3the 3patient
- reduced 3turnaround 3time 3for 3test 3results 3to 3expedite 3medical
, 3decision 3making 3in 3operating 3rooms, 3emergency 3department, 3and
3intensive 3care 3units
questions and answers latest
top score.
epitope CORRECT ANSWER.An Ab molecule is an immunoglobulin (Ig) with a
functional domain known as F(ab); this area of the Ig protein binds to a
site on the Ag. An Ag is relatively large and complex and usually has
multiple sites that can bind to antibodies (Abs) with different specificities;
each site on the Ag is referred to as an antigenic determinant or
hapten CORRECT ANSWER.small molecule that has to bind to a larger molecule
to form an antigen
The affinity for the Hp is related to the likelihood to bind or to the degree of
complementary nature of each
Affinity CORRECT ANSWER.is the tendency of a chemical species such as an
atom or molecule to react with another to form a chemical compound
avidity CORRECT ANSWER.refers to the accumulated strength of multiple
affinities of individual non-covalent binding interactions
likely hood of separation
cross-reactivity CORRECT ANSWER.an Ab can react with an Ag that is
structurally similar to the homologous Ag
radial immunodiffusion (RID) CORRECT ANSWER.is an immune precipitation
method used to quantitate protein (the Ag).
,In this method, monospecific antiserum is added to the liquefied agarose;
then, the agarose is poured into a plate and cooled.
Wells are cut into the solidified agarose. Multiple standards, one or more
quality control samples, and patient samples are added to the wells.
The Ag diffuses from the well in all directions, binds to the soluble Ab in
the agarose, and forms a complex seen as a concentric precipitin ring.
The diameter of the ring is related to the concentration of the Ag that
diffused from the well. A standard curve is constructed to determine the
concentration in the quality control and patient samples.
The usable analytic range is between the lowest and highest standards. If
the ring is greater than the highest standard, the sample should be diluted
and retested. If the ring is less than the lowest standard, the sample should
be run on a low-level plate. Two variations exist: the endpoint (Mancini)
method and the kinetic (Fahey-McKelvey) method.
Ouchterlony technique CORRECT ANSWER.The simplest and least sensitive
method is double diffusion.
Agarose is placed on a solid surface and allowed to solidify. Wells are cut
into the agarose. A common template is six Ab wells, surrounding a single Ag
well in the center. Soluble Ag and soluble Ab are added to separate wells and
diffusion occurs. The intensity and pattern of the precipitation band are
interpreted.
The precipitin band of an unknown sample is compared with the precipitin
band of a sample known to contain the Ab. A pattern of identity confirms the
presence of the Ab in the unknown sample. Patterns of partial identity and
nonidentity are ambiguous.
This technique can be used to detect Abs associated with autoimmune
diseases, such as Sm and ribonucleoprotein detected in systemic lupus
erythematosus, SSA and SSB in Sjögren's syndrome, and Scl-70 in
progressive systemic sclerosis. However, most of these Abs are also
detected using enzyme-linked immunoassays or multiplex bead array
systems (e.g., Luminex Corp).
Fluorescence polarization immunoassay (FPIA) CORRECT ANSWER.is another
assay that uses a fluorescent label
This homogenous immunoassay uses polarized light to excite the
fluorescent label. Polarized light is created when light passes through
special filters and consists of parallel light waves oriented in one plane.
When polarized light is used to excite a fluorescent label, the emitted light
could be polarized or depolarized. Small molecules, such as free fluorescent-
labeled Hp, rotate rapidly and randomly, interrupting the polarized light.
,Larger 3molecules, 3such 3as 3those 3created 3when 3the 3fluorescent-labeled 3Hp
3binds 3to 3an 3Ab, 3rotate 3more 3slowly 3and 3emit 3polarized 3light 3parallel 3to 3the
3excitation 3polarized 3light.
The 3polarized 3light 3is 3measured 3at 3a 390° 3angle 3compared 3with 3the 3path 3of
3the 3excitation 3light. 3In 3a 3competitive 3FPIA, 3fluorescent-labeled 3Hp 3and
3unlabeled 3Hp 3in 3the 3sample 3compete 3for 3limited 3Ab 3sites.
When 3no 3unlabeled 3Hp 3is 3present, 3the 3labeled 3Hp 3binds 3maximally 3to 3the
3Ab, 3creating 3large 3complexes 3that 3rotate 3slowly 3and 3emit 3a 3high 3level 3of
3polarized 3light.
When 3Hp 3is 3present, 3it 3competes 3with 3the 3labeled 3Hp 3for 3the 3Ab 3sites; 3as
3the 3Hp 3concentration 3increases, 3more 3labeled 3Hp 3is 3displaced 3and 3is 3free.
3The 3free 3labeled 3Hp 3rotates 3rapidly 3and 3emits 3less 3polarized 3light. 3The
3degree 3of 3labeled 3Hp 3displacement 3is 3inversely 3related 3to 3the 3amount 3of
3unlabeled 3Hp 3present
Microparticle 3capture 3enzyme 3immunoassay 3(MEIA) 3CORRECT 3ANSWER.is 3an
3automated 3assay 3available 3on 3the 3AxSYM 3Analyzer 3(Abbott 3Laboratories).
3The 3microparticles 3serve 3as 3the 3solid 3phase, 3and 3a 3glass 3fiber 3matrix
3separates 3the 3bound 3labeled 3reagent.
Both 3competitive 3and 3noncompetitive 3assays 3are 3available. 3Although 3the
3label 3is 3an 3enzyme 3(ALP), 3the 3substrate 3(4-methylumbelliferyl 3phosphate) 3is
3fluorogenic.
Point-of-care 3testing 3(POCT) 3CORRECT 3ANSWER.is 3defined 3as 3"those 3analytical
3patient- 3testing 3activities 3provided 3within 3the 3institution, 3but 3performed
3outside 3the 3physical 3facilities 3of 3the 3clinical 3laboratories.
These 3include 3tests 3for 3electrolytes, 3glucose, 3hemoglobin 3A1c, 3urinalysis,
3pregnancy, 3drugs 3of 3abuse, 3therapeutic 3drug 3monitoring, 3occult 3blood,
3blood 3gases, 3coagulation 3tests, 3enzymes, 3and 3cardiac 3markers. 3POCT 3is
3also 3available 3for 3infectious 3diseases 3such 3as 3HIV, 3gonorrhea, 3syphilis,
3streptococcus, 3influenza, 3fungal 3infections, 3and 3tuberculosis
POCT 3offers 3several 3advantages 3compared 3with 3central 3laboratory 3testing.
3The 3major 3advantage 3of 3POCT 3is 3faster 3delivery 3of 3results. 3POCT 3is
3designed 3to 3work 3with 3the 3flow 3of 3patient 3management 3and 3care, 3allowing
3physicians 3to 3order 3and 3perform 3the 3test 3and 3immediately 3make 3a 3medical
3decision
Portability 3of 3POCT 3allows 3for 3increased 3access 3to 3testing 3in 3a 3wider 3variety
3of 3sites, 3for 3example, 3rural 3areas, 3accident 3sites, 3areas 3with 3limited
3infrastructure 3and 3personnel, 3and 3locations 3with 3underserved 3populations
Comparing 3POCT 3to 3Lab 3Testing 3CORRECT 3ANSWER.Advantages
- convenience 3for 3both 3the 3attending 3physician/nurse 3and 3the 3patient
- reduced 3turnaround 3time 3for 3test 3results 3to 3expedite 3medical
, 3decision 3making 3in 3operating 3rooms, 3emergency 3department, 3and
3intensive 3care 3units
