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42 Cards in this Set
- Front
- Back
total protein is measured using serum, which lacks ___
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fibrinogen, as does the SPEP sample
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cathode vs anode
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cathode(negative pole, attracts cations)
anode(positive pole, attracts anions) |
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column separation: gel filtration using beads rated by pore size; larger molecules move __ through column
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fastest, because they move through interstices of the column and do not enter the pores of the beads
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anion exchange vs cation exchange chromatography
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anion:
- alkaline pH - proteins are negatively charged and exchanged with anions from salt buffer cation: - acid pH - proteins are positively charged - displaced by cations from salt buffer |
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affinity chromatography is used for __
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quantitating glycosylated hemoglobin
- use antibodies fixed to a solid support medium w/in a column |
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proteins in soln absorb UV light at what wavelength? what about nucleic acids?
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proteins: 280 nm; mostly due to tryptophan content
nucleic acid: 260 nm If using spectrophotometric assays to quantitate protein, must correct for nucleic acid content protein conc (mg/mL)= 1.55 A(280) - 0.76A(260) |
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Specific gravity can be used to estimate protein content; it uses __
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copper sulfate
- drop of blood or serum added to a graded series of copper sulfate solns - the drop can remain stationary, drop, or float to top - protein conc is estimated from the specific gravity of the copper sulfate soln in which the drop remained stationary - commonly used for Hb screening (what the drop to drop to bottom) |
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Biuret method
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- extensively used for protein quant, esp in automated analyzers (see below Lowry method)
- specific for proteins - in alkaline soln, copper salts form a complex with molecules with two or more peptide bonds (biuret complex) - biuret complex absorbs UV light at 540-560nm - reliable down to 10-15mg/dL Lowry method: uses the biuret method followed by phenol reagent, which greatly enhances the color reaction - |
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Albumin can be quantitated in samples contain other protein by virtue of its __
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specific binding to certain dyes
- commonly used dye is BCG(bromcresol green); extensively used in automated analyzers - often measure albumin in parallel with total protein by the biuret method - BCG-alb absorb at slightly different wavelength |
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Nephelometry
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detects turbidity produced by precipitation of reagent antibody with its target protein
- specific - |
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prealbumin
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AKA: transthyretin (TTR)
- faster than albumin (anodal to albumin) - small protein - binds little thyroxine (TBG has a 100-fold higher affinity for thyroxine) - plays significant role in vitA metabolism; TTR binds retinol bindind protein which binds vitA to transport it thorughout body - TTR-RBP complex keeps the small RBP from being rapidly clear through the kidney - TTR-RBP-retinal complex is formed in the ER of hepatocytes |
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Type I familial amyloidotic polyneuropathy
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- due to mutation in prealbumin, which makes it susceptible to proteolysis and the release of beta-structured fragments thah lead to amyloid deposits in nerve fibers
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Prealbumin has a relatively __ half-life
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2 days
- its synthesis rate is very sensitive to adequate nutrition and changes in liver function - serum prealbumin levels - useful marker for nutritional status |
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prealbumin can cross into the __
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CSF! due to its small size
- CSF electrophoresis (concentrated of course) shows a distinct preablumin band, not seen in SPEP or UPEP - normal CSF electrophoresis pattern: prealbumin, albumin, and small transferrin bands |
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What could lead to the presence of a "pseudo prealbumin" band on SPEP
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- patients given heparin
- heparin activates lipoprotein lipase in vivo, which alters the triglyceride content of lipoproteins and thus their electrophoretic mobility - RESULT: see a band in the prealbumin area due to altered beta-lipoproteins - this is an in vivo effect that does not occur if heparin is added to an already collected samples |
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congenital analbuminemia is characterized by a __
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compensated hydrostatic pressure, with no major fluid abnormalities
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Many albumin variants exist; most cause ___
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No clinically significant abnormality
- Bisalbuminemia: 2 albumin bands on SPEP - Exception: one variant has a high affinity for thyroxine, leading to elevated T3, but normal FT3 and a euthyroid state |
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half-life of circulating albumin is __
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17 days
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Fructosamine (aka___) can be useful for monitoring diabetic control in patients with ____; in place of glycosylated hemoglobin
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aka: glycosylated albumin
- useful in patients with hemolytic anemias (sickle cell dz, AIHA, thalassemias) in whom glycosylated Hb is unreliable - normally up to 8% of albumin is glycosylated |
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elevated serum albumin is due to __
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- uncommon
- dehydration - prolonged used of tourniquet |
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albumin is a negative acute phase reactant
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decreased in many conditions (non-specific)
- malnutrition - protein-losing enteropathy - nephropathy - liver disease |
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decreased albumin can be associated with a decrease in what two common cations
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Mg2+ and Ca2+
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nephrotic syndrome with loss of albumin; can see a compensatory rise in ___ in order to maintain oncotic pressure
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alpha-2-macroglobulin (alpha-2 band)
- some increased production - also selective retention due to large molecular size |
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In cirrhosis, a loss of albumin synthesis can be associated with a compensatory rise in __ in order to maintain oncotic pressure
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gamma-globulin fraction
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Vast majority of people are ___ for the fully active __ allele of alpha-1-antitrypsin (AAT)
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homozygous
fully active M allele PiMM - 10% are heterozygous for PiM(other); 2% of these are PiMZ |
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In AAT def, Pi__ is associated with ___ and ___ disease
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homozygous PiZZ
- hepatic and pulmonary disease - |
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Can screen for AAT def using __
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SPEP
nephelometry (serum AAT levels) - must be confirmed by more specific assay, give the vast number of potential mutations (75 different alleles exist!) |
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AAT deficiency, therapy is useful for __, but not __
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- useful for treatment of pulmonary emphysema; IV AAT replacement
- prevention of pulmonary emphysema; inhaled AAT - AAT replacement is does not improve cirrhosis that develops in children |
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Cirrhosis secondary to AAT develops in __ and is treated with __
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children (PiZZ)
- liver transplant - recipient takes on the donor's AAT phenotype!! (liver synthesizes AAT) |
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The largest major non-immunoglobulin serum protein is __
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alpha-2-macroglobulin (AMG)
- rises 10-fold in nephrotic syndrome due to selective retention due to size, while albumin is lost - may also be increased synthesis (absolute increase) - maintains oncotic pressure |
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haptoglobin migrates in the __ region on SPEP
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alpha-2 region along with AMG
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serum haptoglobin can help evaluation a positive urine dipstick test for blood in the absence of intact RBCs
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- the dipstick test actually test for pseudoperoxidase activity of heme, found in both Hb and myoglobin
- if serum haptoglobin is low, this suggest hemolysis with hemoglobinuria - if serum haptoglobin is high, this suggest myoglobinuria - also LDH1 is alos a/w hemolysis, while CK is released in rhabdomyolysis |
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The major beta-globulin is __
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transferrin
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transferrin transport iron in the ___ state
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ferric (Fe3+)
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transferrin mRNA sythesis is increased in the __ in response to __
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liver!!
- response to low serum iron and hepatocyte iron |
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transferrin can produce a pseudoparaprotein on SPEP in cases of __
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severe iron deficiency
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chonic transferrin saturation occurs in ___
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idiopathic hemochromatosis and transfusion-related hemosiderosis
- almost no U(unsaturated)IBC |
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screening for hemochromatosis can be accomplished by __
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measure:
- serum iron - transferrin (TIBC) calculate: - percent saturation |
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Hereditary Hemochromatosis results in __
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cirrhosis
diabetes cardiomyopathy arthritis other endocrine d/o toxic effects of excess free iron deposition - tx w/ phlebotomy and/or chelation therapy |
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Variants of transferrin can be seen; produce a __ on SPEP
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doublet bands for transferrin
(heterozygotes) |
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Transferrin is produced by the liver; it is a glycoprotein, in which various sugar molecules are added to newly synthesized proteins
In contrast, in the CSF there is ___ |
In the CSF there is a variant of transferrin that lacks sialic acid residues (asialotransferrin)
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Asialotransferrin (aka___) is found in __ and is useful in __
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aka: tau protein or beta-2-transferrin
CSF (also vitreous and endolymph) - it has slightly less negativity, thus is located slightly more cathodal to transferrin CSF contains both transferrina and asialotransferrin Plasma contain ONLY transferrin If question is whether or not clear fluid leakage from a fistula or skull injury represents CSF - protein electrophoresis can help - if two beta bands (transferrin and asialotransferrin) are present, it is presumptive evidence of CSF - if only one beta band (transferrin only) it is not CSF IMPORTANT: Must do serum (SPEP) in conjunction, two rule out the posibility of a transferrin variant in the serum; thus also given two beta bands, mimicking CSF findings |