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Biomedical subjects

A Scholer

Publications and source records attributed to A Scholer.

At least 19 recordsLinked to original sources
PubMed2001

Drug interference in clinical chemistry: recommendation of drugs and their concentrations to be used in drug interference studies.

A group of international experts prepared two lists of drugs with their serum/plasma and urine concentrations, which should be used when evaluating the performance of a new laboratory method. The two lists were verified by running in vitro interference studies in three European laboratories on Hitachi instruments. The study identified the following new interferants: acid phosphatase in serum by ibuprofen and theophylline; non-prostatic acid phosphatase in serum by cefoxitin and doxycycline; creatine kinase MB in serum by doxycycline; total bilirubin in serum (Jendrassik-Grof method) by rifampicin and intralipid; total bilirubin in serum (DPD method) by intralipid; creatinine in serum (Jaffe method) by cefoxitin; fructosamine in serum by levodopa and methyldopa; uric acid in serum by levodopa, methyldopa and tetracycline; carbamazepine in serum by doxycycline, levodopa, methyldopa and metronidazole; digitoxin in serum by rifampicin; phenytoin in serum by doxycycline, ibuprofen, metronidazole and theophylline; theophylline in serum by acetaminophen, cefoxitin, doxycycline, levodopa, phenylbutazone and rifampicin; tobramycin in serum by cefoxitin, doxycycline, levodopa, rifampicin and phenylbutazone; valproic acid in serum by phenylbutazone; C3 in serum by intralipid; C4 in serum by doxycycline; rheumatoid factor in serum by ibuprofen and metronidazole; pancreatic amylase and total amylase in urine by acetylcysteine, ascorbic acid, cefoxitin, gentamicin, levodopa, methyldopa and ofloxacin; magnesium in urine by acetylcysteine, gentamicin and methyldopa; beta2-microglobulin in urine by ascorbic acid; total protein in urine by ascorbic acid, Ca-dobesilate and phenylbutazone. Interference in acid phosphatase, creatine kinase MB and bilirubin methods was observed at very low analyte concentrations, and therefore it may not be evident at higher concentrations. The study confirmed the usefulness of the recommendation.

Blood Chemical Analysis↗
PubMed2001

Chest pain early after percutaneous coronary intervention: incidence and relation to ECG changes, cardiac enzymes and follow-up events.

To investigate the incidence of chest pain early after percutaneous coronary interventions and its correlation with ECG changes, cardiac enzymes, clinical and procedural variables and follow-up events, we prospectively studied 199 patients (84% male; mean age, 60.1 +/- 9.4 years) after primary successful percutaneous coronary interventions (21% PTCA; 79% additional stent implantation). During the first 16 hours following the intervention, the occurrence of chest pain was noted, ECGs were recorded and serial measurements of cardiac enzymes were performed. Seventy-six patients (38%) with elevated enzyme levels at time 0 were excluded. A clinical follow-up was obtained at 6 months. Forty patients (32.5%) experienced chest pain; new ECG changes were detected in 3 (2.5%). The mean levels of all enzymes were significantly higher in patients with chest pain 16 hours after the intervention. In patients with chest pain versus those without, CK-MB mass and troponin I levels higher than twice the upper normal limit were seen in 43.6% versus 11.0% (p < 0.0001) and 45.0% versus 17.3% (p < 0.002), respectively. Elevated troponin I (< 0.004) and CK-MB mass (< 0.04) as well as presumed ischemic chest pain (< 0.03) could be identified as risk factors for recurrent chest pain during follow-up. In conclusion, chest pain was common early after percutaneous coronary interventions and correlated with elevated cardiac enzymes, suggesting peri-interventional myocardial necrosis. Elevated levels of CK-MB mass and troponin I, as well as presumed ischemic chest pain, were associated with recurrent chest pain during follow-up.

Aged↗
PubMed2000

Interpreting complex urinary patterns with MDI LABLINK: a statistical evaluation.

The measurement of urinary marker proteins is not a generally accepted laboratory practice because the results are difficult to interpret. MDI-LABLINK is software for classifying patterns of specific urinary marker proteins. The interpretations are completely user definable thanks to a specific 'pattern definition database'. Our interpretation set is based on Hofmann and Guder's work in measuring and interpreting single urinary proteins. We include additional marker proteins in order to adapt Boesken's SDS-PAGE classification. During the last 3 years, 1905 patterns were fully differentiated and identically interpreted. Firstly, the samples were classified into three patterns: normal (25.8%), predominantly glomerular (27.2%, selective, unselective, mixed, and with additional tubular proteins) and predominantly tubular (36.9%, complete/incomplete form, with additional glomerular proteins); 8.9% showed postrenal proteinuria. Secondly, glomerular selectivity measured by using urinary transferrin/IgG ratio alone correlates well with the established SI index (the ratio between IgG and transferrin clearances). Thirdly, the creatinine concentration substantiates the validity of the sample. The quality of the preanalytical phase can be improved through the ongoing education of the medical staff. Finally, measurement of urinary albumin and alpha-1-microglobulin is mandatory where kidney disease is suspected, has to be ruled out, or requires close monitoring, even when the total protein concentration is normal.

Adolescent↗
PubMed2000

Increase of bone mineral density with sodium fluoride in patients with Crohn's disease.

BACKGROUND AND AIMS: Low bone density with an increased risk of vertebral fractures is a frequent complication in inflammatory bowel disease. Since the aetiology of osteopathia in these patients is different compared to postmenopausal or steroid-induced osteoporosis, no treatment strategy is established. Supplementation of calcium and vitamin D has been shown to prevent further bone loss, but no data are available showing the anabolic effect of sodium fluoride in Crohn's disease. METHODS: We carried out a one-year prospective clinical trial in 33 patients with chronic active Crohn's disease who were randomly assigned to receive either calcium (500 mg b.i.d.) and 1000 IU vitamin D3 only, or retarded-release sodium fluoride (25 mg t.i.d.) additionally. The diagnosis of Crohn's disease had been made at least two years ago, and all patients had received systemic high-dose steroid therapy during the previous year. Eleven of 15 patients who received calcium/vitamin D and 15 of 18 patients who additionally received sodium fluoride completed the study. The primary endpoint of the study was the increase of bone mineral density, measured by dual energy X-ray absorptiometry (DXA) after one year of treatment. Bone-specific alkaline phosphatase and osteocalcin were used as markers for bone turnover. RESULTS: In the calcium/vitamin D only group, bone density was not significantly changed after one year of treatment, whereas in the calcium/vitamin D/fluoride group, bone density of the lumbar spine increased from -1.39+/-0.3 (Z-score, mean +/- SEM) to -0.65+/-0.3 (P<0.05) after one year of treatment. Increase of bone density was positively correlated to the osteoblastic markers bone-specific alkaline phosphatase (r = 0.53) and osteocalcin (r = 0.43). CONCLUSIONS: Sodium fluoride in combination with vitamin D and calcium is an effective, well-tolerated and inexpensive treatment to increase lumbar bone density in patients with chronic active Crohn's disease and osteoporosis.

Adult↗
PubMed1997

Comparability of a new turbidimetric digoxin test with other immunochemical tests and with HPLC--a multicenter evaluation.

A new turbidimetric inhibition immunoassay for digoxin (Tina-quant [a] Digoxin, Boehringer Mannheim) was evaluated in seven laboratories. It can be performed without sample pretreatment with ready-to-use reagents on nondedicated analyzers in combination with routine clinical chemistry. The studies revealed a good analytical performance: lower limit of detection 0.12 microg/L (3 SD from mean of blank); linearity up to 7.5 microg/L; median between-run CVs 8.1% (0.6 microg/L), 2.8% (1.5 microg/L), 1.9% (3 microg/L); mean analytical recovery in control sera 98-102%; slopes from 0.97 to 1.09 and intercepts from -0.28 to 0.10 microg/L in comparison with four immunoassays; and a high resistance to common interferents. The test was more resistant to digoxin-like immunoreactive factor (DLIF) interference than other methods, showing cross-reactivity only in some intensive care patient samples. Among 192 patients in whom DLIF is expected (e.g., pregnant women, patients with renal failure, newborns), 90% of results were < or =0.26 microg/L digoxin. Cortisol showed no cross-reactivity and digoxigenin had a low reactivity. An interlaboratory survey revealed a good comparability of the Tina-quant [a] test with the median of all methods (slope 0.99, intercept -0.06 microg/L). An HPLC method for digoxin based on isocratic separation of samples on an RP-18 column followed by detection by an immunoassay yielded a reasonable comparability with the immunochemical tests with noncritical samples. Divergent results of immunoassays caused by DLIFs or different cross-reactivities with digoxin metabolites or derivatives can be explained by the use of this HPLC method.

Anticoagulants↗
PubMed1997

European multicentre evaluation of the analytical performance of the Abbott AxSYM Abused Drugs Assays.

In accordance with the guidelines of the European Committee for Clinical Laboratory Standards (ECCLS), the performance of the Abbott AxSYM Abused Drugs assays were evaluated and compared with the results provided by the following systems: Syva Emit d.a.u./Roche Cobas Mira S Plus, Abbott TDx and ADx, Syva Emit d.a.u./Syva ETS Plus, Syva Emit II/Hitachi 717 and Roche Abuscreen OnLine/Roche Cobas Mira S Plus. The test analytes, cannabinoids, cocaine metabolites, opiates, benzodiazepines and barbiturates, were each investigated in three laboratories on different systems. The imprecision of all systems in the series and from day to day was good, with CVs less than 5% or 10%, respectively. The AxSYM calibration curves were stable for 3-4 months and none of the systems displayed any shift in the results of the analyses within one day or any faults caused by sample contamination. Within the framework of this study, a total of 1860 urine samples were investigated; 741 results were positive. All results which remained discrepant between AxSYM and the comparison systems after repeated analysis (n = 17) were subjected to further investigation using a reference method, with the exception of one barbiturate and two benzodiazepine samples. An additional test criterion was the practicability of the systems investigated and the versatility of the software. During this evaluation, the results provided by the Abbott AxSYM were excellent and were fully in line with the manufacturer's claims. The reliability of the FPIA technology that has been the subject of frequent investigation was also convincing during this evaluation. The possibility of semi-quantitative determination, the stability of the calibration curves, the ability to process an emergency sample without delay and its high suitability to routine operations are the convincing benefits offered by this system.

Calibration↗
PubMed1993

Assessment of lidocaine metabolite formation in comparison with other quantitative liver function tests.

In clinical practice, the seriousness of liver disease is assessed based on the combined information from clinical examination, routine biochemical tests, and liver histology. Recently, the assessment of hepatic lidocaine metabolism has been proposed as a quantitative liver function test offering valuable additional information. To evaluate whether this new liver function test reflects the combined clinical assessment, we prospectively measured lidocaine metabolism in 111 patients with well characterized liver disease. In addition, lidocaine test results were compared with the aminopyrine breath test and the galactose elimination capacity. Lidocaine (1 mg/kg) was injected i.v. and serum concentrations of its main metabolite monoethylglycinexylidide were determined after 15 min. The results varied widely and the means (+/- S.D.) were similar among patients with mild liver disease (46 +/- 23 ng/ml), but significantly (P < 0.05) lower among patients with Child class A cirrhosis (19 +/- 11 ng/ml) or Child class B or C cirrhosis (21 +/- 19 ng/ml). The [13C]aminopyrine breath test, however, gave a better discrimination among patients with increasing severity of liver disease than lidocaine metabolite formation. The galactose elimination capacity finally best separated patients with mild liver disease from those with cirrhosis. The correlations between any two of the different quantitative liver function tests were weak (R2 consistently < 0.2). We conclude that lidocaine metabolite formation, like other quantitative liver function tests that are based on the microsomal metabolism of model compounds, quantitates a very particular enzymatic reaction which may not be representative for the functional reserve of the entire organ.

Adolescent↗
PubMed1987

Computer-assisted individualized lidocaine dosage: clinical evaluation and comparison with physician performance.

The performance of a computerized dosing aid in achieving a target serum concentration of lidocaine in the middle of the recommended therapeutic range (3.5 mg/L) was evaluated in 63 patients treated for acute ventricular arrhythmias. In all patients a serum concentration measurement was obtained shortly after starting lidocaine infusion. In 22 patients a microcomputer program based on a Bayesian forecasting technique was used for dosing recommendations, whereas in 41 the serum concentration was interpreted and the dose was adjusted by the unaided physician. Both groups were similar with respect to the average concentration achieved (control: 3.8 +/- 1.13 [SD] mg/L, computer-aided: 3.5 +/- 0.59 mg/L). However, the interindividual variability was significantly larger in the control group (95% confidence interval: 1.5 to 6.1 mg/L vs 2.3 to 4.7 mg/L [p less than 0.01]). Nine of the 41 patients in the control group had a lidocaine concentration outside the recommended therapeutic range of 2 to 5 mg/L compared to only 1 of 22 in the computer-aided group. Lidocaine concentrations greater than 2 mg/L were associated with significantly more effective suppression of ventricular arrhythmias (p less than 0.05). The results show that Bayesian forecasting outperforms the physician in early adjustment of lidocaine dosage based on serum concentration measurements.

Aged↗
PubMed1985

Continuous-flow analysis for glucose with use of glucose dehydrogenase immobilized in glass tubes.

We describe a method for determining glucose in serum with glucose dehydrogenase immobilized on the inner walls of glass tubes. The reactor was incorporated into a channel of a continuous-flow analyzer (the Technicon SMAC) and used daily for four weeks in routine analysis for serum glucose. During this period we tested the linearity, precision, accuracy, and durability of the reactor. Results correlated well (r = 0.9949) with those obtained by routine methods with free (nonimmobilized) glucose dehydrogenase. The method is shown to be practicable for use in the routine laboratory.

Autoanalysis↗
PubMed1984

Evaluation of a colorimetric test for the determination of alpha-amylase with p-nitrophenylheptaoside as substrate.

A continuous method for the determination of alpha-amylase activity with a defined substrate has been published by Rauscher et al. in Berichte der Osterreichischen Gesellschaft für Klinische Chemie 4, 150 (1981). It offers the following advantages: good practicability, easy adaptation to analysers and short incubation time. Twenty-one laboratories took part in a multicentric study on this method, working with different instruments and manual procedures at three temperatures. Additionally, all laboratories participated in a laboratory improvement program, in order to discriminate systematic from accidental errors. Data on imprecision, linearity, interferences and comparability of the method have been presented at a workshop. The resulting coefficients of variation for imprecision in series as well as from day to day were 0.6-6.3% and 1.3-7.7%, respectively. No interferences from bilirubin, glucose, maltose and 37 selected drugs were found. The results from the described method correlate well with those from an UV-test (substrate: maltoheptaose); compared with other methods, however, the expected systematic deviations were observed. Reference values for 25, 30 and 37 degrees C are indicated in this report.

Colorimetry↗
PubMed1983

[Diagnostic value of the determination of serum amylase and serum lipase in suspected acute onset of acute or chronic pancreatitis].

In a prospective study the value of serum amylase and serum lipase determination has been analyzed in 19 patients with an acute episode of acute or chronic pancreatitis and in 19 patients with acute abdomen not due to pancreatitis. The concentration of urinary amylase and the urinary output of amylase in the spot urine as well as after a two-hour collection period have also been examined. The normal values were determined in 21 healthy volunteers and the reproducibility of the various parameters was analyzed after 1 hour and 25 hours in these volunteers. For diagnosis of an acute episode of chronic pancreatitis serum amylase was found to have good sensitivity, but a specificity inferior to that of serum lipase. By contrast, the specificity of serum lipase is excellent. Unlike determination of serum enzymes, measurement of urinary enzymes in all variations does not offer any further advantage. Except for the combination of serum amylase and serum lipase, none of the other tested combinations provides further diagnostic information. The examination of spot urine samples is not inferior to the 2-hour urine specimen. For the time being the combination of serum amylase and serum lipase determination is again recommended for diagnostic routine in patients with an acute episode of pancreatitis.

Abdomen, Acute↗