A, lanes. -7) and lipid (panel. B, lanes 8-14). The LDL was from patient 1 with glucose lanes. 1 and 13), patient 1 ..... Mills GI, Lane. PA,. Weech. PK. Laboratory.
nodular
adrenocortical
dysplasia.
Arch
Intern
Med
1988;148:
Malchoff
16.
1978;24:1040. Beech NF, Buoy ME, Haller WS, Johnson HJ, Beech PK. Radioimmunoassay for 4-androstenedione-3,17-dione, including the synthesis, production, and characterization of the antiserum. Clin Chem 1986;32:1357-67 [Proposed Selected Method]. 22. Valenta U, Elias AN, Iyer K. Pluripotent steroidogenesis and 21.
1133-6.
CD, Rosa J, DeBold
CR, et al. Adrenocorticotropin.
independent bilateral macronodular adrenal hyperplasia: usual cause of Cushing’s syndrome. J Clin Endocrinol 1989;68:855-60. 17. Yamaji T, Ibayashi H. Plasma dehydroepiandrosterone in normal and pathological conditions. J Clin Endocrinol
an unMetab
ultrastructure sulfate Metab
1969;29:273-8. 18. Collins S, Klonowski M, Bermes E, Brooks M. Radioimmunoassay of urinary free cortisol with aggregated antibodies. J Nucl Med 1978;19:758. 19. Collins S, Whisler B, Kahn S, Brooks MH, Bermes EW. A
simplified [Abstract].
testosterone Clin Chem
radioimmunoassay
for routine
clinical
use
1981;27:1057. 20. Collins S, Brooks MH, Bermes EW, Frank JJ. A micro technique for cortisol in unextracted serum [Abstract]. Clin Chem
CLIN. CHEM. 35/11, 2219-2223
Effect of Glycation Apolipoprotein B RIchard
of Low-Density
Lipoprotein
causing
Cushing’s
syn-
Yamaji T, Ishibashi M, Sekthara H, Itabashi A, Yanaihara Serum dehydroepiandrosterone sulfate in Cushing’s syndrome.
T.
24.
J Clin Endocrinol Metab 1984;59:1164-8. 25. Fig LM, Gross MD, Shapiro B, et al. Adrenal localization in the adrenocorticotropic hormone-independent Cushing syndrome. Ann Intern Med 1988;109:547-.53.
on the Immunological
Determination
of
D. Press and Peter WIldIng
glycation of low-density lipoprotein (LDL) may contribute to the premature atherogenesis of patients with diabetes mellitus. To assess whether glycation of apolipoprotein B, the predominant protein of LDL, interferes with the ability to immunologically quantify this protein, we prepared and purified glycated LDL by incubating normal plasma samples with high concentrations of glucose. Although both the plasma and the LOL specimens incubated with glucose contained significantly more glycated protein than control specimens, the quantitative interaction of an apolipoprotein B-specific antibody with glycated vs nonglyLOL
was
not significantly
different.
We
conclude
apolipoprotein B can be accurately quantified cally despite the presence of clinically excessive LDL glycation. AddItIonal
Keyphrases:
diabetes
mel/if us
that
immunologidegrees of
atherogenesis
immunonephelometry
Non-enzymatic primary
glycation
initiating
event
of proteins in the
is thought
pathogenesis
to be a
of many
of the
clinical complications (1). In particular,
of long-standing diabetes mellitus glycation of apolipoprotein B, the major of low-density lipoprotein (LDL) has been
apolipoprotein shown to occur in vitro (2, 3) and in vivo (3) after prolonged hyperglycemia. Involvement of this glycated LDL in the accelerated atherogenesis characteristic of prolonged diabetes
adenomas
(1989)
Non-enzymatic
cated
in adrenocortical
drome. Horm R,es 1987;25:97-104. 23. Cheitlin RA, Westphal M, Cabrera CM, Fujii DK, Snyder J, Fitzgerald PA. Cushing’s syndrome due to bilateral adrenal macronodular hyperplasia with undetectable ACTH: cell culture of adenoma cells on extracellular matrix. Horm Res 1988;29: 162-7.
has
recognition increased
been
suggested
by
reports
of
impaired
of glycated LDL by the LDL receptor (4) and cholesterol ester accumulation by monocyte/mac-
Department the University
of Pathology and Laboratory Medicine, Hospital of of Pennsylvania, 3400 Spruce St., Philadelphia, PA
19104.
Received
both
June
20, 1989;
accepted
July
20, 1989.
rophage trations
cells exposed to glycated of apolipoproteins A and
LDL (5). Because B in serum may
concenbe better
predictors of atherogenic risk than is the typical cholesterol or lipoprotein analysis (6), more clinical laboratories have begun offering apolipoprotein measurements, predominantly by immunological methods with use of commercial apolipoprotein-specific antibodies. To assess whether non-enzymatic glycation of LDL apolipoprotein B had any quantitative effect on the interaction of this protein with the antibody used for its clinical determination, we used an immunonephelometric assay to compare the amounts of apolipoprotein B in LDL purified from plasma samples that had been pre-incubated with or without high concentrations of glucose. We found that, although the LDLs from the plasma specimens incubated with glucose were significantly more glycated than the control LDLs, this degree of glycation had no significant effect on the quantitative immunological determination of apolipoprotein B.
MaterIals
and
Methods
Specimens: Plasma was sampled from 10 donors with no clinical evidence of diabetes. These samples included five outdated units of fresh-frozen plasma, three fresh specimens obtained after therapeutic plasma exchange from patients with chronic inflammatory demyelinative polyneuropathy, one fresh specimen obtained after therapeutic phlebotomy one
fresh
from
a patient
specimen
from
with a healthy
After dialysis against isotonic EDTA per liter to remove the
polycythemia laboratory
vera,
and
technologist.
saline containing 1 mmol of preservatives and anticoag-
ulants required for plasma storage, the 10 plasma specimens were each divided into two identical 15-mL aliquots. To one of each pair of 10 specimens we then added concentrated glucose (210 g/L solution) to give a final concentration of 9.0 g/L; the other received no addition. All speci-
CLINICAL
CHEMISTRY,
Vol. 35, No. 11, 1989
2219
mens, seven saline excess
with or without added glucose, were incubated for days at 37 #{176}C, then were dialyzed against isotonic containing 1 mmol of EDTA per liter to remove glucose. Plasma specimens were then stored at 4#{176}C
until
further
analysis.
Preparation
prepared by densitydescribed by Kelly and Kruski (7), NaBr solutions being replaced by equal-density solutions of KBr. Each 12.5-mL ultracentrifuge tube containing 4.0 mL of plasma was centrifuged in a Beckman SW4O rotor at 26300 rpm for 16 to 24 h at 4 #{176}C. The LDL, visible as a yellow band migrating about a third of the way down the tube, was harvested with a Pasteur pipette (approximately 1.5 mL of LDL per tube) and stored at 4#{176}C in its high-salt buffer. Electrophoresis: For electrophoresis on agarose gels we used commercially prepared gel plates (Helena Laboratories, Beaumont, TX) as described in the manufacturefs instructions. Proteins were detected by staining with Amido Black, and lipoproteins by staining with Fat Red 7B. The concentrations of cholesterol and total protein in the plasma and LDL specimens were determined by using an Ektachem 700 analyzer (Kodak, Rochester, NY) and the appropriate dry-ifim slides (8). Fructosamine assays: We measured fructosamine in plasma in a Cobas Mira centrifugal analyzer, using reagent (nitro blue tetrazolium), fructosainine calibrator solution, and fructosamine standards provided in a commercial kit (Rotag; Roche Diagnostic Systems, Nutley, NJ). The analyzer was programmed as recommended by the kit manufacturer (20 L of sample, 50 /hL of diluent, 200 pL of reagent; measurements at 550 nm after 10 and 15 min). The assay was calibrated before each test run, and each plasma specimen was analyzed at least in duplicate. We measured fructosamine in purified LDL specimens in a Cobas Mira analyzer programmed to deliver 75 zL of sample, 20 L of diluent, and 200 L of NBT reagent. Measurements were made at 550 nm after 2.5 and 20 mm at 37 #{176}C. We confirmed the linearity of the assay curve in the range of 0.1 to 0.3 mmol of fructosamine per liter, using a 3 mmoIfL calibrator solution serially diluted into the 1.019 kg/L density-gradient buffer. The assay was calibrated before each test run with the 3 mmol/L calibrator gradient
of LDL:
LDL
was
ultracentrifugation
as
Table 1. In Vitro Fructoesmlne, Patient
Results We used plasma from 10 nondiabetic patients for in vitro glycation reactions, isolation of LDL, and determination of LDL-specific glycation and recognition of apo B antibody. Before incubation with or without glucose, we confirmed the absence of significant in vivo protein glycation in any of these samples by measuring plasma fructosamine, a quantitative means of assessing protein glycation based on the reactivity in alkaline medium of ketoamine groups with nitro blue tetrazolium (9). Each of the 10 plasma specimens had a fructosamine concentration well below the cutoff of 2.7 mmol/L exhibited by >95% of nondiabetics (Table 1). After a seven-day incubation with glucose, however, there was a significant (P 0.35) in protein glycation between specimens incubated for seven days with no added glucose [mean fructosaxnine 1.8 (SD 0.5) mmol/L] and those same specimens before incubation [mean fructosamine 1.8 (SD 0.2) mmol/L]. The increased fructosamine in specimens 3,4, and 5 after incubation without added glucose probably
of Plasma
Proteins
mmol/L
Protein,
g/L
Before
With
WIth
Without
Incubation
glucose
glucose
glucose
glucose
1.86 1.67 2.16
58
58 36
Without
1
2.00
2
1.60
3
1.44
4.28 ND 3.76
4
1.95
4.39
2.61
43
45
5 6
1.70 1.61
3.98
2.43
3.50
1.32
42 37
41 38
7
1.92
3.52
1.31
46
48
8 9
2.14 1.80
3.40
1.96
3.12 3.51
1.55 1.32 1.61
1.81 (0.22)
3.72 (0.42)
1.79 (0.47)
44 43 46 44.6 (6.5)
46 44 51 43.3 (6.3)
10 Mean
Glycatlon
solution diluted to about 0.2 mmol/L, and each LDL specimen was analyzed in triplicate. Apolipoprotein B assay: Concentrations of apolipoprotein (apo) B were determined by an automated immunonephelometric assay on a Behring nephelometer with polyclonal apo B-specific rabbit antibody provided in a commercial kit (Behring Diagnostics, La Jolla, CA). We calibrated the assay at least once every eight days with standards provided by Behring, and before each test run the apo B concentrations of control serum specimens from two independent sources (Behring, and Bio-Rad Labs., Richmond, CA) were confirmed. Statistics: We evaluated the fructosamine and totalprotein measurements by the paired Student’s t-test to determine the significance of differences between samples incubated with or without glucose. Significance was defined as a P value of 2.8 mmol/L), compared with none of the control plasma pecimens in this range (Table 1). These higher frucosamine values in the samples treated with glucose could tot be attributed to a significant difference in total protein t)ncentration between these pairs of samples [mean proem concentration with glucose, 45 (SD 7) g/L; without lucose, 43 (SD 6 g/L); P >0.05; Table 1]. Again, the low nncentrations of total protein in all of these samples )robably resulted from nonspecific protein losses during lialysis. The significant difference in fructosamine between hese sample pairs was therefore clearly the result of an tccelerated rate of non-enzymatic glycation in the presence mfhigh concentrations of glucose. To assess whether this increase in protein glycation in he plasma specimens treated with glucose resulted in ipecific glycation of LDL, we purified LDL from each of the 0 plasma samples by ultracentrifugation. Agarose gel tlectrophoresis of these LDLs revealed a single species tfter staining for either protein or lipid (Figure 1), implyng that the purified LDL was free of contaminating protein md lipoprotein. The increased electrophoretic migration of hese LDLs (into the pre-13 region in the lipid gels and the t-(3 interzone in the protein gels) was not characteristic of DL from fresh plasma (Figure 1, lane 14). This alteration n LDL mobility probably resulted from accelerated oxida;ive degradation, lipolysis, or albumin-binding during proonged incubation at 37 DC. We noted this characteristic ncrease in gel mobility only in LDLs purified from plasma ncubated at 37 DC for seven days, and not from fresh
Ai
2
3
4
5
6
7
I
F.a2
a1 Albumin
9
10
11
12
13
14
#{149} ig.
1. Purification
of LDL
.DL specimens purified by density.gradient ultracentrifugation were electrohoresed through agarose gels and stained for both protein (panel A, lanes -7) and lipid (panel B, lanes 8-14). The LDL was from patient 1 with glucose lanes 1 and 13), patient 1 without glucose (lanes 2 and 12), patient 9 with plucose (lanes 3 and 11), patient 7 with glucose (lanes 4 and 10), patient 9 without glucose (lanes 5 and 2), patient 7 without glucose (lanes 6 and 2), or resh normal human plasma (lanes 7 and 14). The other 14 LDL specimens howed
an identical
single
band pattern
on both types
of gels (data
not shown)
plasma (data not shown). Similar degradative changes in LDL have been documented after prolonged storage at 4#{176}C (10) and the resulting LDL, like ours, had increased electrophoretic mobility. Table 2 shows the results of replicate determinations of the extent of glycation in the 20 LDL samples, expressed as reactivity in a modified fructosamine assay. Concentrations of total cholesterol were also determined for each of these LDL specimens, and to control for variability in the quantitative yield of LDL per preparation, the data are expressed as millimoles of fructosamine per gram of LDL cholesterol. For each of the 10 LDL pairs, the relative extent of glycation of the sample exposed to glucose was greater than that of its paired control, the mean increase being 37% (0.136 to 0.186 mmollg). Statistical analysis of these pairs revealed a highly significant (P 0.4; Table 2). Thus, despite an average 37% increase in glycation of apolipoprotein B in the LDLs incubated with vs without glucose, the antibody used to immunologically quantify this protein interacted normally with its antigen binding site. Discussion Using a modified fructosamine assay to quantify protein glycation, we have shown here that prolonged exposure of plasma to high concentrations of glucose results in a specific non-enzymatic glycation of LDL ape B, and that this modified ape B can interact with ape B-specific antibodies to the same extent as does nonglycated ape B. Other studies have demonstrated the presence of glycated LDL after in vivo or in vitro hyperglycemia by use of methods such as m-aminophenyl boronate affinity chromatography (12, 13), radioimmunoassay with antibodies specific for glucitollysine adducts (14), glucitollysine mass measurement in an amino acid analyzer (3), the trinitrobenzenesulfonic acid assay (4), or reduction of glucitollysine adducts with tritiated sodium borohydride (3,15). In comparison, our methodology took advantage of the ability of ketoamine groups to reduce nitro blue tetrazolium in alkaline medium into a colored product (9). Application of this fructosamine assay to fractions of purified LDL allowed a quantitative assessment of the extent of glycation of ape B, the major protein of LDL. The absence of other contaminating proteins in our LDL preparations (Figure 1) eliminated a major limitation of the fructosainine assay, namely the preferential reactivity of the more abundant protein species in heterogeneous mixtures (12, 16). Because non-enzymatic glycation of intraand extravascular proteins probably contributes to many of the lifethreatening complications of long-standing diabetes (1), a role for glycated LDL in promoting the accelerated atherogenesis characteristic of diabetics would be an attractive CLINICAL
CHEMISTRY,
Vol. 35, No. 11, 1989
2221
Table 2. Assessment Glucose IncubatIon
Patient 1
2
Fructosamine, mmol/L
1.59 1.81
0.149 0.108
1.04
0.27 0.26
1.74 2.06
1.69 2.10
0.153
0.971 1.02
0.74 0.78
0.93 0.90
0.210 0.141
1.25
-
0.16 0.11
+
0.19
0.87
0.92
0.215
1.05
-
0.17
1.00
1.61 0.99 1.13 1.17 1.01 0.72
0.167 0.171 0.132 0.172 0.115
+
0.28 0.22 0.17 0.13 0.28 0.18 0.13
1.07 1.67 1.78 1.05 1.22 1.39 1.23 0.82
1.07 1.03 1.06 1.06 1.08 1.18 1.21 1.14
-
0.11
0.92
1.02
0.121
1.11
0.16 0.13 0.13 0.12
0.93 1.07
0.169 0.125
0.66
0.91 1.09 0.71
0.83
0.84
+
0.20 (0.06)
1.09 (0.40)
1.16 (0.38)
-
0.16 (0.05)
1.22 (0.44)
1.30(0.43)
0.146 0.186 (0.029) 0.136 (0.022)
0.973 1.02 1.08 1.01
+ -
+ -
8 9
+ -
10
+ -
Mean
(SD)
LOL fractions
purified from plasma specimens
determinations (except for patient 3 on whom was 12% for fructosamlne, 10% for cholesterol,
to
cholesterol
to control for variations in
1.68
incubated with (+) or without only a single cholesterol and apo
CLINICAL
CHEMISTRY,
glucose
(-)
B
0.127
0.178 0.181
0.200
were assayed as described. represent
1.15
0.240
assay was done). For these duplicate
and 13% for apo B. The last two columns per sample.
1.03
the calculated
Shown
is
the
1.08(0.09)
1.08 (0.07) mean
of at least
two separate
determinations the maximum inter-run CV ratio of either fructosamine or apo B relative
LDL yield
pathological model. In support of such a model, glycated LDL has been found to be recognized less efficiently than control LDL by the ape B-specific LDL receptor (3,4, 17). Furthermore, glycated LDL, when incubated with monocytes/macrophages, stimulates the rates of cholesterol ester synthesis relative to control LDL (5, 18). LDL is not, however, the only protein to become functionally altered upon glycation, because non-enzymatic glycation of serum albumin results in both a specific protein conformational change and a decreased binding affinity for bilirubin and fatty acids (19). A model thus arises where glycated LDL, poorly recognized by the classic LDL receptor, accumulates to high extracellular concentrations and is cleared via alternative LDL receptors (such as the monocyte/macrophage scavenger receptor). These alternative LDL receptors stimulate accelerated rates of cholesterol ester synthesis and may therefore lead to the transformation of macrophages into the lipid-laden foam cells characteristic of early atheromatous fatty streaks. Like glycated LDL, LDL modified by chemical processes such as oxidation or acetylation is also preferentially recognized by alternative LDL receptors (20), implying a common atherogenic pathway for LDL damaged by various means. Although our patient group failed to include any diabetics, exposure of normal plasma to high concentrations of glucose resulted in specimens with degrees of protein glycation (mean fructosamine 3.7 mmol/L) exceeding those of even the most poorly controlled groups of diabetics (21-23). Unless there is some fundamental difference in the distribution of protein glycation in vivo vs in vitro, these data imply that, even at the highest degrees of LDL glycation likely to be encountered in a clinical setting, there is no impairment of the interaction between ape B 2222
Apo B/ cholesterol, g/g
1.52 1.75
-
7
Fructosamlne/ cholesterol, mmol/g
0.23
+
6
Apo B, g/L
0.19
+
5
Cholesterol, g/L
-
-
4
LDL
+
+
3
of Purified
Vol.35,
No. 11, 1989
and the antibody used for its quantitative assessment. Immunological assays should therefore be an accurate means of quantifying apo B concentrations, even in poorly controlled diabetics. The concentration of apo B may represent a superior index of atherogemc risk than standard cholesterol or lipoprotein assays (6), so it may be especially important to follow ape B concentrations in high-risk diabetic patients, either before or during treatment of hyperlipidemia. The inability of polyclonal antibody to distinguish glycated from nonglycated ape B may reflect a true inability of protein side-chain chemical modification to alter the interaction between antibody and antigen. Alternatively, it is possible that either the extent of protein glycation is not sufficient to cause a visible effect on antibody binding or the antibody itself lacks the avidity or specificity required for the differential effect to be measurable. Clinically, however, these alternatives are of little practical consequence because degrees of glycation greater than those produced here are unlikely to be encountered, and because in mos commercially available ape B immunoassays the polyclonal antibodies are similar to those used here. Despite thi inability of commercial reagents to distinguish glyca from nonglycated ape B, the different biochemical characteristics of these two related species suggest distinct in viv recognition mechanisms that may contribute to the overal pathogenesis of hyperglycemia. References 1.
end
Brownlee
products
complications. 2. Sasaki J,
M, Cerami in
tissue
N Engi
Cottam
A, Vlassara H. Advanced glycosylatio and the biochemical basis of diabeti J Med
1988;318:1315-21.
GL. Glycosylation
of human
LDL
and
i
netabolism
in human skin flbroblasts. ommun 1982;104:977-83. L Witzum JL, Mahoney EM, Branks
Biochem
Biophys
Res
MJ, Fisher M, Elam R, D. Nonenzymatic glucosylation of low density lipoproam alters its biologic activity. Diabetes 1982;31:283-91. t. Steinbrecher UP, Witzum JL. Glucosylation of low density ipoproteins to an extent comparable to that seen in diabetes slows steinberg
heir catabolism. Diabetes 1984;33:130-4. . Lyons TJ, Klein RL, Baynes JW, Stevenson HC, Lopes-Virella 4F. Stimulation of cholesteryl ester synthesis in human monoyte-derived macrophages by low density lipoproteins from type I liabetic patients: the influence of non-enzymatic glycosylation of ow density lipoproteins. Diabetologia 1987;30:916-23. . Naito HK. The clinical significance of apolipoprot.ein measurenents. J Clin Immunoassay 1986;9:11-20. T. Kelly JL, Kruski AW. Density gradient ultracentrifugation of ;erum lipoproteins in a swinging bucket rotor. Methods Enzyrnol L986;128:170-81. . Dappen GM, Cumbo PE, Goodhue CT, et al. Dry film for the mzymatic determination of total cholesterol in serum. Clin Chem L982;28:1159-62. I. Johnson RN, Metcalf PA, Baker JR. Fructosamine: a new Lpproach to the estimation of serum glycosyl-protein. An index of liabetic control. Clin Chim Acta 1982;127:87-95. 10. Mills GI, Lane PA, Weech PK. Laboratory techniques in )iochemlstry and molecular biology. A guidebook to lipoprotein echniques. Amsterdam: Elsevier, 1984:449-59. Li. Albers JJ, Brunzell JD, Knopp RH. Apoprotein measurements uid their clinical application. Clin Lab Med 1989;9:137-52. [2. Zoppi F, Mosca A, Granata S, Montalbetti N. Glycated proteins n serum: effect of their relative proportions on their alkaline reducng activity in the fructosarnine test. Clin Chem 1987;33:1895-7.
)LIN.
CHEM.
35/11,
2223-2226
Clinical Chemistry aboratory Unit lana SuIIInger1
(1989)
Analyzer
and Patricia
Evaluated
by NCCLS
comparison study of “dry chemistry” desktop malyzers, the ChemPro 1000 (Arden Medical Systems) was me of several instruments found suitable for field use. We ave now evaluated the linearity, accuracy, and precision of he ChemPro 1000, according to NCCLS Document EP 10-P. We also compared results with those by the SMAC Technicon) and the Nova 9 (Nova Biomedical) for electroytes, serum urea nitrogen, and ionized calcium in field and boratory environments. The precision (CV) of the ChemPro within
acceptable
Guidelines
for Use in a Military
Field
E. Garrett2
n a previous
vas
13. Jack CM. Non-enzymatic glycosylation of low density lipoprotein. Results of an affinity chromatography method. Diabetologia 1988;31:126-8. 14. Curtiss LK, Witzum JL. Plasma apolipoproteins Al, AU, B, CI, and E are glucosylated in hyperglycemic diabetic subjects. Diabetes 1985;34:452-61. 15. Lyons TJ, Baynes JW, Patrick JS, Coiwell JA, Lopes-Virella MF. Glycosylation of low density lipoprotein in patients with type 1 diabetes: correlations with other parameters of glycaemic control. Diabetologia 1986;29:685-9. 16. Rodriguez-Segade 5, Lojo S, Camina MF, Paz M, Del Rio R. Effects of various serum proteins on quantification of fructosamine. Clin Chem 1989;35:134-8. 17. Gonen B, Baenziger J, Schonfeld G, Jacobson D, Farrar P. Nonenzymatic glycosylation of low density lipoproteins in vitro: effects on cell-interactive properties. Diabetes 1981;30:875-8. 18. Lopes-Virella MF, Klein RL, Lyons TJ, Stevenson HC, Witzmn JL. Glycosylation of low density lipoprotein enhances cholesteryl ester synthesis in human monocyte-derived macrophages. Diabetes 1988;37:550-7. 19. Shaklai N, Garlick RL, Bunn HF. Non-enzymatic glycosylation of human serum albumin alters its conformation and function. J Biol Chem 1984;259:3812-7. 20. Steinberg D, Parthasarathy S, Carew TE, Khoo JC, Witzum JL. Beyond cholesterol: modifications of low density lipoprotein that increase its atherogenicity. N Engl J Med 1989;320:915-24. 21. Lim YS, Staley MJ. Measurement of plasma fructosamine evaluated for monitoring diabetes. Clin Chem 1985;31:731-3. 22. Jury DR, Dunn PJ. Laboratory assessment of a commercial kit for measuring fructosainine in serum. Clin Chem 1987;33:158-61. 23. Jerntorp P, Sundkvist G, Fex G, Jeppsson JO. Clinical utility of serum fructosamine in diabetes mellitus compared with hemoglobin A1C. Clin Chim Acta 1988;175:135-42.
ranges
for
dry
chemistry
tnalyzers for all analytes tested. This instrument tnd reasonable alternative to manual chemistry tutomated instrumentation in a field environment.
desktop
is a suitable or to large,
The in the
ability to perform fundamental field is essential to the mission
has
allowed
decentralization
provide timely sions while the the suitability analyzers in tient-comparison
1323D Medical Laboratory, Armed Forces Reserve Center, lanscom AFB, MA 01731, and (address for correspondence) Deartment of Pathology, Massachusetts General Hospital, Boston, IA 02114. 2Department of Laboratory Medicine, Lahey Clinic, Burlington, ,IA 01805. Current address: Boston Biomedica, Inc., 375 West St., Vest Bridgewater, MA 02379. Received March 15, 1988; accepted July 26, 1989.
chemistry
analyses
of a military medical laboratory unit. The standard manual chemistry methods require water-based reagents, which are bulky and difficult to transport and keep from damage during mobilization. The methodology is laborious and requires specially trained personnel. Current automated analyzers are impractical in a field setting. Recently, the development of “dry chemistry” desktop analyzers for physicians’ offices results patient
of some
laboratory
services
to
for diagnostic waits (1-5).
or management deciDoos et al. (6) examined
of several portable a mobile army field
dry chemistry desktop laboratory. In that pa-
study,
all
of the
instruments
tested
were
found to be “field suitable.” Although it did not have applications for all of the required analytes, the ChemPro 1000 (Arden Medical Systems, St. Paul, MN) was the instrument of choice because of its ease of use and low requirement for temperature-sensitive, fragile, or bulky consumables. We undertook the present study specifically to evaluate linearity, accuracy, and precision in a field laboratory setting, with the evaluation based on the guideCLINICAL
CHEMISTRY,
Vol. 35, No. 11, 1989
2223
