Analytical evaluation and comparison of Dupont aca lactate dehydrogenase-1 (LD1) isoenzyme assay diagnostic efficiency for acute myocardial infarction detection with other LD1 methods and aca CK-MB. A two-site study

The purpose of this study was to examine the analytical characteristics of a rapid new assay for lactate dehydrogenase 1 (LD1) isoenzyme on the Dupont aca analyzer and the diagnostic efficiency of LD1 for detection of acute myocardial infarction (AMI) when used alone and with creatine kinase MB (CKMB). Total aca LD1 assay precision, with percent coefficients of variation (%CVs) of less than 3.2% from 56 U/L to 469 U/L LD1, across fifty assay days was excellent. Linearity was confirmed from 0 to 332 U/L and no detectable calibration drift was noted from 5 to 489 U/L over a ninety-day period. The aca LD1 results compared well with Roche Isomune-LD1, Abbott Spectrum A-Gent, Helena electrophoresis, and Beckman electrophoresis LD1 methods, giving r's from 0.987 to 0.994, slopes from 0.94 to 1.65, and y-intercepts from -2.95 to 6.94 U/L. Examination of 450 ambulatory subjects, about equally distributed by sex, yielded a 43 +/- 14 U/L aca LD1 patient reference interval. Serum samples from 159 consecutive patients at the University of Tennessee Memorial Hospital and 96 patients at Allentown Hospital, submitted for AMI detection assistance, were assayed in a single-blind study for LD1 and ion-exchange CKMB by Dupont aca methods, which provide automated results in ten minutes whenever needed. The aca LD1 assay yielded a clinical sensitivity of 89% and specificity of 95% for AMI with a decision threshold of 120 U/L. The diagnostic efficiency of the aca LD1 assay was 94% at 120 U/L, which equaled or exceeded that of the three comparative LD1 methods. The predictive value of positive (PV+) and negative (PV-) results on the first sample collected were 80% and 85% for aca LD1, 65% and 90% for aca ion-exchange CKMB, and 83% and 90% when both tests were combined. Significantly, the PV+ and PV- results when two or more samples were assayed was improved to 88% and 95% for aca LD1, relatively constant at 65% and 97% for aca ion-exchange CKMB, and dramatically improved to 95% and 100% when both CKMB and LD1 tests were combined. The results from these two medical centers show that the aca LD1 assay provides useful clinical information for AMI diagnosis when employed alone or in combination with aca CKMB. These results also suggest that LD1 should be included in biochemical evaluations for AMI to attain optimal predictive values of results.     

Paraneoplastic limbic encephalitis

BACKGROUND: Polymorphonuclear elastase is an early and sensitive indicator of neonatal infection when performed at the beginning of clinical symptoms. PATIENTS AND METHODS: To investigate the diagnostic value of elastase measurement in cord blood immediately after birth, 211 neonates (103 boys vs 108 girls, 154 vaginal delivery vs 57 cesarean section). Mean gestational age 38.9 weeks (range: 30-42), mean birth weight 3,260 g (range: 1,430-4,920 g). After clinical, bacterial and biological screening, the infants were classified in three groups. Group A (n = 118): none infectious risk factor neither clinical signs of infection; group B (n = 79): one or more risk factors but no evidence of infection; group C (n = 14): proved or probable infection. Polymorphonuclear elastase was measured in cord blood of all infants using an heterogeneous enzyme-linked-immunosorbent assay. RESULTS: We observed higher elastase values in group C (176 +/- 67 micrograms/L) than in group A (91 +/- 64 micrograms/L) and B (67 +/- 61 micrograms/L) (mean +/- SD, P = 0.0001). With a cutoff value fixed at 80 micrograms/L, the sensitivity of this test applicated to neonates presenting materno-fetal infectious risk factor(s) was 85% (12/14), specificity 74% (59/79), positive predictive value 37%, and negative predictive value 96%. CONCLUSION: Because two of the 14 infected infants (15%) were not detected by elastase dosage in cord blood, this test cannot be used as an early indicator of materno-fetal infection.     

Fasting plasma glucose in screening for diabetes in the Taiwanese population

OBJECTIVE: To reveal the relationship between fasting and 2-h postload plasma glucose and to examine the appropriate fasting glucose cutoff as the primary screening test for diabetes. RESEARCH DESIGN AND METHODS: We recruited 5,303 subjects from preventive services of the National Cheng Kung University Hospital. Exclusion criteria were age <20 years, pregnancy, known diabetes, and a history of recent surgery, trauma, or illness. All subjects received the 75-g oral glucose tolerance test. The relationship between fasting and 2-h glucose was examined. Sensitivities, specificities, efficiency, and predictive values were assessed at different cutoffs of fasting glucose for prediction of diabetes. RESULTS: The best fit model for the relationship between fasting and 2-h glucose was fasting glucose = 4.914-0.060 x (2-h glucose) + 0.0144 x (2-h glucose)2. From this model, the fasting glucose was 6.0 mmol/l when 2-h glucose was 11.1 mmol/l. A fasting glucose with 6.25 mmol/l gave the same diabetes prevalence as the World Health Organization 2-h glucose criterion. When 7.8 mmol/l was the fasting glucose cutoff, the sensitivity was 28.5%. Lowering the cutoff from 7.8 to 7.0 mmol/l increased the sensitivity by 11.2% and slightly reduced the specificity and positive predictive value. If the cutoffs were 6.25 and 6.0 mmol/l, the sensitivity increased and the specificity and the positive predictive value decreased accordingly. CONCLUSIONS: Our results suggest that fasting glucose as a screening criterion for diabetes could be revised downward to 7.0 mmol/l, because the slight reduction of positive predictive value was more than balanced by an apparent increase of sensitivity and insignificant change of specificity.     

Effects of tachykinin receptor antagonists, FK224 and FK888, in a guinea-pig model of nasal allergy

BACKGROUND: Since the development of the radioallergosorbent test (RAST) for quantification of allergen-specific IgE, numerous non-radoisotopic methods have been devised which combine the proven cellulose disc technology with enzyme-linked immunoassay methods. The HY.TEC EIA (Hycor Biomedical, Inc. Irvine, CA) was compared with Pharmacia CAP with respect to overall system features and assay performance characteristics. METHODS: The HY.TEC EIA and Pharmacia CAP were compared with respect to calibrator range, sensitivity, type of detection, type of solid phase, throughput, and mode of operation. To determine the assay sensitivity and specificity for a variety of allergens, a total of 2,447 tests were performed on both CAP and HY.TEC EIA. The samples were scored positive in both cases using a cutoff of 0.35 IU/mL. RESULTS: The general features of the HY.TEC EIA system are comparable to Pharmacia UniCAP, with the added advantage of higher throughput. Intra-assay precision was 7% and inter-assay precision was 9-15%. Using CAP as a comparative method, HY.TEC EIA has a sensitivity of 94.0% and a specificity of 94.4%. CONCLUSIONS: The HY.TEC EIA demonstrates excellent agreement with the Pharmacia CAP system in the determination of allergen-specific IgE. With the automation necessary in today's clinical laboratory, we conclude that the HY.TEC EIA is a state-of-the-art tool for the diagnosis of allergic disease.     

Absorptive function following small intestinal transplantation

Detection of cardiac troponin I (cTnI) in patients suspected of having an acute coronary syndrome is highly predictive for an adverse outcome. We evaluated a bedside test for cTnI that uses a polyclonal capture antibody and two monoclonal indicator antibodies. Clinical studies were performed in patients with acute coronary syndrome and patients with chest pain but no evidence of acute myocardial injury. The whole-blood, 15-minute assay had a concordance of 98.9% with an ELISA for cTnI and a detection limit of 0.14 microg/L, and the device tolerated temperatures between 4 degrees C and 37 degrees C. Diagnostic sensitivity for myocardial infarction at arrival (3.5 +/- 2.7 h after onset of symptoms) was 60% [creatine kinase isoenzyme MB (CK-MB) mass, 48%; CK activity, 36%; P < 0.01], and 4 h later, diagnostic sensitivity was 98% (CK-MB mass, 91%; CK activity, 61%; P < 0.01). In 38% of the patients with unstable angina, at least one positive cTnI test was found (CK-MB mass, 4%; CK activity, 2%). No false-positive test results were found in renal failure or injury of skeletal muscle. We conclude that the diagnostic efficacy of the cTnI rapid test was comparable with the cTnI ELISA and superior to CK-MB determination. Therefore, this device could facilitate decision-making in patients with chest pain at the point of care.     

Prostate carcinoma staging. Clinical utility of bone alkaline phosphatase in addition to prostate specific antigen

BACKGROUND: Biochemical markers of bone disease have been of interest as part of the investigation of prostate carcinoma and the monitoring of skeletal involvement. Bone isoenzyme of the alkaline phosphatase (BAP) is an indicator of the metabolism of the osteoblasts. An immunoradioanalyses with two monoclonal antibodies in sandwich was developed, allowing an accurate measurement of BAP concentration. The goal of the current study was to compare the clinical performance of BAP and prostate specific antigen (PSA) in patients with untreated prostate carcinoma and to determine whether or not BAP can provide valuable additional information to PSA regarding the degree of skeletal extension in patients with prostate carcinoma. METHODS: BAP and PSA serum concentrations were determined in 140 newly diagnosed prostate carcinoma patients (72 M0 and 68 M1-4). The efficiency of both markers in the prediction of positive bone scans was studied as well as the relationship observed between the concentrations of the two markers and the degree of skeletal involvement. To investigate the potential utility of BAP and PSA in eliminating the need for a bone scan, the negative predictive values for different cutoff points for both markers were calculated. RESULTS: BAP was more efficient than PSA in the prediction of positive bone scans and its level was significantly related to the magnitude of skeletal involvement whereas PSA was only able to distinguish between M0 and M1-4 groups of patients. The highest predictive value for a bone scan result was found for BAP cutoff values between 20 and 30 ng/mL, leading to negative and positive predictive values of 92.6% and 98.2%, respectively. The combination of BAP and PSA both set at a 20 ng/ mL cutoff value yielded a negative predictive value of 100% and the combination of BAP and PSA at 30 ng/mL and 20 ng/mL cutoff values, respectively, increased the positive predictive value to 98.5%. CONCLUSIONS: This study suggests that BAP could be a complementary marker to PSA in the diagnosis of bone disease in patients with prostate carcinoma. Its clinical utility could result in important cost saving implications, eliminating bone scan when PSA ranges from 10 to 20 ng/mL because the predictive negative value of PSA < 20 ng/mL and BAP < 20 ng/mL is 100% in this series. In addition, it could provide useful clinical information regarding the degree of skeletal involvement.     

Inhibition of lipid peroxidation with the lazaroid U74500A attenuates ischemia-reperfusion injury in a canine orthotopic heart transplantation model

BACKGROUND: The lazaroid U74500A is a 21-aminosteroid that inhibits lipid peroxidation and attenuates ischemia-reperfusion injury. We examined the effect of U74500A on heart preservation with the use of a clinically relevant canine orthotopic heart transplantation model. METHODS AND RESULTS: Six donor dogs (group L) were pretreated intravenously with U74500A (10 mg/kg), and the dogs without pretreatment served as a control (group C, n = 6). The donor heart was preserved in cold University of Wisconsin solution for 24 hours. The heart was then transplanted orthotopically. Myocardial biopsy was performed to measure the adenosine triphosphate level at the end of ischemia. Before reperfusion, recipients in group L received another dose of U74500A (10 mg/kg) intravenously. After 3 hours of reperfusion, left ventricular function was evaluated by left ventricular pressure-volume relations with the use of a Millar catheter and conductance catheter, thereby deriving the slope of the end-systolic pressure-volume relation, the slope of the stroke work-- end-diastolic volume relation, and the slope of the maximum dP/dt--end-diastolic volume relation. At the same time, serum creatine kinase MB isoenzyme and lipid peroxide levels were measured. The slopes of the end-systolic pressure-volume relation, the stroke work--end-diastolic volume relation, and the maximum dP/dt--end-diastolic volume relation for group L were significantly higher than those for group C. The adenosine triphosphate levels for group L were significantly higher than those for group C. Serum creatine kinase MB isoenzyme and lipid peroxide levels for group L were significantly lower than those for group C. CONCLUSIONS: Inhibition of lipid peroxidation by the administration of U74500A was effective for 24-hour canine cardiac preservation. These results indicate that U74500A is a promising agent for heart allograft preservation.     

Islet cell antibodies are less predictive of IDDM among unaffected children in the general population than in sibs of children with diabetes. The Childhood Diabetes in Finland Study Group

OBJECTIVE: To examine the controversial issue of whether islet cell antibodies (ICAs) have a higher predictive value for progression to clinical IDDM in first-degree relatives of patients with diabetes than in the general population. RESEARCH DESIGN AND METHODS: ICAs were analyzed with standard immunofluorescence in two population-based groups: 765 sibs of children with recent-onset diabetes and 1,212 unaffected Finnish children <20 years of age at initial screening. Those positive for ICAs were additionally tested for antibodies to GAD (GADAs) and the protein tyrosine phosphatase-related IA-2 antigen (IA-2As). Subsequently, these subjects were observed for the manifestation of clinical IDDM over the next 7 years. RESULTS: The frequency of both detectable ICAs and ICA levels > or =20 Juvenile Diabetes Foundation units (JDF U) was significantly higher among the sibs than in the general population (7.8 vs. 4.1% and 4.8 vs. 2.0%, respectively; P < 0.001). The prevalence of GADAs (37/60 vs. 3/48; P < 0.001) and IA-2As (31/60 vs. 0/48; P < 0.001) was increased among ICA-positive sibs compared with ICA-positive individuals from the background population. Over the next 7 years, 24 sibs (3.1%) and 3 unrelated children positive for ICAs (0.3%) progressed to clinical diabetes. The positive predictive value of ICAs was thus 6% in the general population and 40% among the sibs (P < 0.001), or 13 and 59%, respectively (P < 0.001), with an antibody cutoff level of 20 JDF U. The positive predictive value was related to the number of positive autoantibodies in sibs, which was 57% in those with three antibodies, 50% in those with two antibodies, and only 6% in those with ICAs alone. CONCLUSIONS: These data show that the frequency of multiple autoantibodies is substantially lower in ICA-positive children representing the general population than in ICA-positive sibs of children with IDDM. As a consequence, the predictive value of ICAs for IDDM is higher in sibs of affected children than in the general population. This finding must be taken into account when planning intervention trials aimed at preventing or delaying the manifestation of clinical diabetes in individuals from the general population who test positive for ICAs.     

Automated measurement of peak widths for the determination of peak capacity in complex chromatograms

In a large number of cases, the etiology of community-acquired pneumonia (CAP) is not established. Some cases are probably caused by Streptococcus pneumoniae. Transthoracic needle aspiration (TNA) culture has a limited sensitivity which might be improved by antigen detection or gene amplification techniques. We evaluated the capacity of a PCR assay and a latex agglutination test to detect S. pneumoniae in samples obtained by TNA from 95 patients with moderate-to-severe CAP. Latex agglutination and PCR had sensitivities of 52.2 and 91.3%, specificities of 88.7 and 83.3%, positive predictive values of 62.3 and 65.6%, and negative predictive values of 83.3 and 96.5%, respectively, when culture techniques were used as the "gold standard." When we considered expanded criteria for the diagnosis of pneumococcal pneumonia as a standard for our calculations, latex agglutination and PCR had sensitivities of 53.6 and 89.7%, specificities of 93.0 and 90.0%, positive predictive values of 78.9 and 81.3%, and negative predictive values of 80.3 and 94.7%, respectively. The additional diagnosis provided by the PCR assay compared to latex agglutination was 12.2% (95% confidence interval of the difference from 0.4 to 20. 1%). PCR was more sensitive than TNA culture, particularly in patients who had received prior antibiotic therapy (83.3 versus 33. 3%). Although PCR is a very sensitive and specific technique, it has not proved to be cost-effective in clinical practice. Conversely, latex agglutination is a fast and simple method whose results might have significant implications for initial antibiotic therapy.     

Clock-face drawing, reading and setting tests in the screening of dementia in Chinese elderly adults

Comprehensive neuropsychological batteries focus on the subtle cognitive deficits in dementia, but a brief screening instrument is also of immense practical value. As the clock-drawing test encompasses a number of cognitive domains frequently disturbed by the dementing process, it is considered to be a suitable screening instrument for the disorder. We documented the usefulness of a new scoring method of the clock-drawing test for screening of dementia in the elderly Chinese in Hong Kong. Fifty-three demented individuals and 53 healthy elderly controls were assessed. At a cutoff score of 3/4, the sensitivity and specificity of the clock-drawing test in screening of dementia was 83% and 79%. With a composite test of clock reading and clock setting, the positive predictive value of the clock face test was 98%. This new scoring method of clock-drawing proved to be a valid measure for screening of dementia. It is applicable in non-English speaking populations and should be a useful adjunct for quick screening assessment of dementia.     

Usefulness of angiotensin converting enzyme inhibitors in the diagnosis of renovascular hypertension. III. Evaluation of the validity of the captopril test and the reno-scintigraphic captopril test in the diagnosis of renovascular hypertension according to accepted criteria

The aim of the study was to evaluate diagnostic validity of captopril test and scintigraphic test before and after captopril for the detection of renovascular hypertension (RVH) according to applied criteria. Employing blood pressure response to captopril as a criteria sensitivity was 37.0%, specificity 92.1%, positive predictive value 75.0% and negative predictive value 70.2% in the captopril test. Applying plasma renin activity (PRA) response to captopril as a criteria sensitivity was 92.5%, specificity 100%, positive predictive value 100% and negative predictive value 96.0% in the same test. Renin captopril test has excellent sensitivity and positive predictive value, is easy to perform and inexpensive and therefore may be a useful screening test for RVH in unselected population. With the own criteria used, captopril renoscintigraphy detected RVH with 87.5% sensitivity, 91.7% specificity, 87.5% positive predictive value and 91.7% negative predictive value. Captopril renoscintigraphy is an accurate diagnostic test for the identification of RVH in a clinically selected high-risk population. Common evaluation of both tests does not improve their accuracy in diagnosis of RVH.     

Diagnostic implications of kinetics of immunoglobulin M and A antibody responses to Toxoplasma gondii

We evaluated immunoglobulin M (IgM) and IgA assays that could improve the predictive value for recently acquired toxoplasma infection for patients with positive screening test results. Follow-up sera were collected from 82 patients whose initial serum specimen had a reactive anti-Toxoplasma gondii IgM result. According to the evolution of the immune response, patients were divided retrospectively into two groups: one in which a recent infection was unlikely and the other one with an evolving immune response suggestive of recent toxoplasma infection. All IgM and one of three IgA assays used in the study are suitable for screening pregnant patients, with a negative predictive value of 100%. The predictive value of positive results is much lower because of the low prevalence of acute toxoplasmosis in pregnant women and the long persistence of IgM after acute infection. In the present study, all except one IgM enzyme immunoassay remained positive well beyond 6 months after the initial sample was tested. The IgM immunofluorescence test had the shortest persistence of positivity in most cases. IgA tests were either too insensitive or remained reactive too long to be useful for screening pregnant patients. Interpreting enzyme immunoassays with modified cutoff values and the combination of two tests could improve the predictive value of positive results to about 80% in terms of recent infection.     

Evaluation of an assay for detecting telomerase activity in neoplastic tissues of dogs

OBJECTIVE: To determine feasibility of using the telomere repeat amplification protocol (TRAP) assay to detect telomerase activity in tumors of dogs. SAMPLE POPULATION: Samples of tumor or normal tissue were obtained from client-owned dogs that underwent surgical biopsy during the period of January 1996 through December 1997. PROCEDURE: The TRAP assay was used to detect telomerase activity in malignant or benign tumors of dogs. Telomerase status (positive or negative) was compared with results of histologic examination for each sample to estimate specificity and sensitivity of this assay for the diagnosis of malignancy. RESULTS: Of 26 malignant tumors, 24 were telomerase positive on TRAP assay, whereas 3 of 4 benign tumors and 3 of 3 normal tissues were telomerase negative. Analysis of these results indicated an estimated sensitivity of 92% and specificity of 86% for tumor analysis, using the TRAP assay. CONCLUSION: The TRAP assay can be used to measure telomerase activity in malignant tumors of dogs. CLINICAL RELEVANCE: Because telomerase activation may be required for indefinite longevity of cells, it may also serve as a tumor marker and therapeutic target. The TRAP assay can be used to detect telomerase in samples of fluid as well as tissues obtained from solid tumors. Therefore, it may have considerable clinical value in rapid and noninvasive diagnosis of neoplasia in dogs. Additional studies must be completed to more accurately determine sensitivity and specificity of the assay.     

Perflubron as a gastrointestinal MR imaging contrast agent in the pediatric population

A microplate enzyme immunoassay (EIA) for the detection of lysergic acid diethylamide (LSD) in human urine was developed. The assay kit is designed around an LSD derivative coated on the wall of microplate wells with preservatives and stabilizers. Sample and rabbit anti-LSD are added to the microplate well. The immobilized LSD and LSD present in specimens compete for the opportunity to bind to the anti-LSD antibodies. An anti-rabbit antibody labeled with horseradish peroxidase is used to provide the assay signal, which is inversely proportional to the concentration of LSD in the sample. The assay requires a 25-microL urine sample and three consecutive incubation periods of 60, 30, and 30 min at room temperature. The assay was tested with a variety of drugs, including ergot alkaloids spiked into drug-free urine at up to 100,000 ng/mL without cross-reaction. Nor-LSD was shown to cross-react between 16% and 28%, depending on its concentration. Of the other compounds tested, only ergonovine demonstrated slight cross-reactivity at approximately 0.0008%. The assay is designed to be used with a qualitative cutoff of 0.5 ng/mL. Precision testing at 0.5 ng/mL gave a coefficient of variation (CV) of 6% based on 20 replicates. The CV at 0.375 ng/mL (cutoff, -25%) was 5.2% and at 0.625 ng/mL was 6.6%. Precision at other concentrations within the range of the calibration curve gave similar results both intra- and interassay. Clinical performance of the assay was compared with that of a commercial radioimmunoassay (RIA). Comparable performance was observed with both methods, each screening a total of 458 samples as negative and 17 samples as positive relative to a 0.5 ng/mL cutoff. The EIA found an additional three positive samples that were negative by RIA. The EIA is suitable for the screening of urine samples for the presence of LSD. Preliminary indications are that the assay is also suitable for use with whole blood specimens. The assay can be performed manually or be fully automated and without the need for radioactivity; it can be used in any laboratory.     

Physiologic, biochemical and genetic aspects of malignant hyperthermia

The value of the TAG-72 (CA 72-4) serum marker in primary diagnosis was investigated in 110 patients with histologically diagnosed ovarian cancer. A reference group consisted of 103 patients with benign pelvic masses. Compared to the well-established CA-125, TAG-72 showed a low sensitivity of 42% in the detection of ovarian cancer. By contrast, when the cut-off level for TAG-72 was set at 6 U/ml, it showed a very high specificity of 99%. When the measurement of TAG-72 was combined to that of CA-125, improvements in both the specificity (as compared to a single CA-125 determination) and the sensitivity (as compared to a single TAG-72 assay) were observed. In such a combined assay, our results suggest that the best predictive value (positive and negative) was obtained if CA-125 is assigned a relatively high cut-off value (65 U/ml) in conjunction with a low cut-off level (3.2 U/ml or 4 U/ml) for TAG-72. In the present study, at threshold values of 65 U/ml respectively, a sensitivity of 86%, a specificity of 83% and a positive and negative predictive value of 85% were obtained. In mucinous carcinomas of the ovary, however, the additional TAG-72 determination did not lead to a better predictive power than did CA-125 measurement alone.     

Efficiency of mixed RASTs in serological screening of possibly allergic patients

OBJECTIVE: To determine the age distribution of results of serological allergy screening using mixed-allergen radioallergoabsorbent tests (RASTs), and to determine the cost-effectiveness of mix RASTs. DESIGN: Retrospective. SETTING: University Hospital of Rotterdam; Dijkzigt Hospital and Sophia Children's Hospital, the Netherlands. METHODS: An analysis was made of the results of all determinations requested in a period of 3 years with use of the CAP Phadiatop test (aimed at IgE against a mixture of inhalant allergens) and the CAP f x 5 food mix test (aimed at IgE against a mixture of food allergens). RESULTS: The CAP Phadiatop test was positive most strongly and most frequently in patients aged 7 to 30 years. From the age of 2 years, there was a sharp rise of the number of positive CAP Phadiatop tests, but IgE against inhalant allergens was also found in over 10% of the children aged 0 and 1 year. Up to and including the age category of 6 years, over one-third of the sera submitted had a positive CAP f x 5 food mix test. From a budget point of view, preliminary screening with a mix RAST is the more advantageous the lower the allergy prevalence and the higher the mean number of CAP-RASTs to be requested per serum. CONCLUSION: A substantial saving of laboratory costs can be achieved by having mix RASTs such as CAP Phadiatop and CAP f x 5 food mix tests precede determinations of specific IgE against separate allergens; these savings will be the higher the smaller the proportion of positive results and the higher the mean number of separate RASTs to be requested per serum.     

Study of serum alanine-aminotransferase levels in blood donors in Spain

BACKGROUND AND OBJECTIVE: Serum alanine-aminotransferase (ALT) is being used as a surrogate test for preventing post-transfusion viral hepatitis. However, ALT elevation is influenced by many factors. We have studied ALT levels in 1,036 consecutive blood donors to determine their association with gender, obesity, and hepatitis virus infection markers. DESIGN AND METHODS: In each donation aspartate-aminotransferase (AST), lactate dehydrogenase (LDH) and gamma-glutamyl transferase (gamma GT) activity were also determined and body mass index (BMI) was calculated. RESULTS: Five hundred seventy-nine men and 457 women donated blood; ALT activity was 25.3 +/- 14.5 IU/L (mean +/- SD) for men and 16.3 +/- 7.9 IU/L for women (p < or = 0.0005). The upper normal value for men was 56 IU/L and 34 IU/L for women. On applying this value to the study group 4.8% of the men and 2% of the women had values greater than the cutoff. Among the men with increased ALT levels, 53.5% had a BMI > 27, 7.1% also had an increased level of GGT and 7.1% had increased levels of AST and LDH. None of them were HBsAg nor anti-HCV positive. Among the women with increased ALT, 33.3% had BMI > 27, 33.3% had increased levels of LDH and AST, and 11.1% were anti-HCV positive (only 1 donor). INTERPRETATION AND CONCLUSIONS: It seems clear that different cutoff values should be considered for men and women. Factors such as obesity, may account for more than 50% of the cases with increased ALT values, indicating the low specificity of the test.     

Human T-cell leukemia virus type II infection frequently goes undetected in contemporary US blood donors

Serologic screening for human T-cell leukemia virus type I (HTLV-I) infection was begun in US blood banks with the licensure of enzyme-linked immunosorbent assays (ELISA) in December 1988. We examined the donation histories of the first 60 Western blot (WB)-confirmed HTLV-I/II positive donors to one blood center and found 8 had made 16 previous donations that scored negative on the screening ELISA. All 16 donations had ELISA absorbance below the cutoff for a positive assay, but still well above that of the average donation (17.6% +/- 5.7% of the cutoff). In a more extensive study, 17 donations from a total of 61,752 at six blood centers were both ELISA-positive and WB-positive for HTLV-I (4) or HTLV-II (13), and 218 samples had ELISA absorbance greater than 50% of the ELISA cutoff. One hundred seventy-eight of the 218 were tested further by WB and 11 were found positive. All 11 positives were confirmed by polymerase chain reaction; 10 had HTLV-II and 1 had HTLV-I. Thus, the HTLV-I-based screening ELISA missed at least 10 of 23, or 43% (95% confidence interval, 23% to 66%), of HTLV-II infections, compared with 1 of 5, or 20%, of HTLV-I infections.     

Effect of angiotensin ii on Na+/H+ exchangers of the renal tubule

A commercial enzyme-linked immunosorbent assay (ELISA) designed to detect allergen-specific immunoglobulin (Ig)E antibodies were evaluated in 36 atopic dogs and in 12 normal dogs. The test showed a sensitivity of 72.23% and a specificity of 41.6%. Positive and negative predictive values were 76.47 and 35.71% respectively. Correlation between the ELISA kit results and intradermal skin testing varied depending on the allergen and ranged from 47.1 to 80.4%, although positive correlation (i.e. allergens positive in both tests) ranged rom 2.7 to 19.4%. In conclusion, this serological test gave both false positive and false negative results. Sensitivity, specificity and predictive values indicate that this ELISA may not be useful in canine atopy. Although correlation studies were hampered by the impossibility of using the same allergenic extracts, the correlation observed between intradermal and serological testing indicates that results from both tests are not interchangeable.     

Measurement of urinary lactoferrin as a marker of urinary tract infection

The usefulness of the measurement of urinary lactoferrin (LF) released from polymorphonuclear leukocytes and of an immunochromatography test strip devised for measuring urinary LF for the simple and rapid diagnosis of urinary tract infections (UTI) was evaluated. Urine specimens were collected from apparently healthy persons and patients diagnosed as suffering from UTI. In the preliminary study, the LF concentrations in 121 normal specimens and 88 specimens from patients (60 with UTI) were quantified by an enzyme-linked immunosorbent assay. The LF concentration was 3,300.0 +/- 646.3 ng/ml (average +/- standard error of the mean) in the specimens from UTI patients, whereas it was 30.4 +/- 2.7 ng/ml and 60.3 +/- 14.9 ng/ml in the specimens from healthy persons and the patients without UTI, respectively. Based on these results, a 200-ng/ml LF concentration was chosen as the cutoff value for negativity. Each urine specimen was reexamined with the newly devised immunochromatography (IC) test strip to calculate the indices of efficacy. Based on the cutoff value, it was calculated that the sensitivity, specificity, and positive and negative predictive values of the IC test were 93.3, 89.3, 86.2, and 94.9%, respectively, compared with the results of the microscopic examination of the urine specimens for the presence of leukocytes. The respective indices for UTI were calculated as 95.0, 92.9, 89.7, and 96.6%. The tests were completed within 10 min. These results indicated that urine LF measurement with the IC test strip provides a useful tool for the simple and rapid diagnosis of UTI.