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Biomedical subjects

B G Blijenberg

Publications and source records attributed to B G Blijenberg.

At least 19 recordsLinked to original sources
PubMed1992

Evaluation of tissue polypeptide antigen serum levels for monitoring disease activity during chemotherapy in patients with transitional carcinoma of the urinary tract.

In 28 patients with transitional carcinoma of the urinary tract, all treated with chemotherapy, serial measurements of serum tissue polypeptide antigen (TPA) were performed and correlated to clinical evaluations of response. At the start of chemotherapy elevated levels of TPA were found in 4 out of 14 patients with T2-4NO-2MO tumours and in 7 out of 14 patients with distant metastases. In most patients with elevated TPA levels who responded to chemotherapy, TPA levels rapidly returned to normal. False positive elevations of TPA were observed in 2 patients. It is concluded that serial measurement of TPA for monitoring disease activity has limited value because of the low sensitivity of TPA, especially for patients with early-stage cancer, and because of the occurrence of false positive results.

Adult↗
PubMed1992

Creatinine and automatic analysers in relation to icteric specimens.

A study is described on the interference of bilirubin with the determination of creatine in serum using three automatic analysers i.e. the Technicon Chem-1, the DuPont Dimension and the Baxter Paramax. In all instruments a kinetic Jaffé reaction is applied. As comparison method we used a HPLC based selected method. All methods proved to be sensitive to interference, the Paramax showing the best performance with our set of specimens. Results regarding modifications leading to improvement and possible future experiments are discussed.

Autoanalysis↗
PubMed1992

Validation of the ultrafiltration technique for creatinine analysis by HPLC: a comparison with direct serum injection.

The determination of creatinine by HPLC was performed by direct injection of serum onto the column, and after ultrafiltration of the sample, and the results were compared. A modified weak cation exchange column was used for HPLC. This eliminates the protein displacement effect and the Gibbs-Donnan effect, thus permitting a rapid direct analysis. Three of the four ultrafiltration methods gave almost identical analytical results. Regression analyses of the results from direct serum injection versus ultrafiltration showed a bias of 5% on the slope y = 1.050 . xpure serum + 1.856, which was in our view solely due to the volume displacement effect of the proteins; correction of each data point by a protein-dependent correction factor resulted in an almost perfect regression line.

Blood Proteins↗
PubMed1992

On the accuracy of the Reflotron creatinine determination.

A study was undertaken to evaluate the accuracy of the Reflotron creatinine determination. Two aspects are reported: the calibration of the instrument and the influence of bilirubin on the test result. As the reference method, an HPLC based technique was used. Variations due to the instrument as well as to the test strip were found, while interference by bilirubin proved to be very moderate.

Autoanalysis↗
PubMed1991

No transketolase abnormalities in Wernicke-Korsakoff patients.

Transketolase isoenzyme patterns of Wernicke-Korsakoff patients, relatives, alcoholics and controls, obtained by isoelectric focusing of purified erythrocyte transketolase, were all identical. After a series of investigations published by several authors little evidence remains to support the hypothesis of an inborn transketolase abnormality in Wernicke-Korsakoff patients.

Adult↗
PubMed1991

Assessment of a selected method for creatinine with special emphasis on bilirubin interference.

An HPLC-based method for the determination of creatinine was evaluated, with emphasis on interference by bilirubin. The method differed from other procedures, in that deproteinization was by ultrafiltration instead of precipitation with trichloroacetic acid. This allows a rapid, direct analysis by HPLC with very few experimental steps. Analytical results showed linearity up to 5000 mumol/l and an average analytical recovery of 100%. Within-day imprecision was 0.8-1.4%, and day-to-day imprecision was 0.5-2.4%.

Bilirubin↗
PubMed1991

Chemical analysis of gallstones.

A new promising treatment for patients with symptomatic cholelithiasis is extracorporeal shock wave lithotripsy. In order to learn how to interpret the computed tomographic (CT) densities of gallstones measured in vivo, our radiologists asked the clinical chemistry laboratory to analyse cholesterol, bilirubin and calcium in gallstones. No reference methods for the analysis of gallstones have been described. A literature search for manageable quantitative methods for these analyses was not successful. Among the different X-ray diffraction, infrared and chemical analyses described, we could find no well documented analyses that have been compared with reference methods or proposed reference methods for serum. This finding prompted us to develop chemical methods for cholesterol, bilirubin and total calcium in gallstones starting from (proposed) reference methods for serum and to investigate the accuracy, imprecision and linearity of these methods.

Bilirubin↗
PubMed1991

Calibration of Technicon Chem 1 multitest analysers.

Recently, two Technicon Chem 1 multitest clinical chemistry analysers were introduced after an evaluation in our laboratory. Calibration according to the instructions of the manufacturer resulted in significant differences between the assay results of the two Chem 1 analysers for twelve of twenty-two methods. To remove these differences we used an additional procedure based on the NCCLS EP-9P protocol for method comparison. Four reference methods were used as comparison methods. Our results indicate that, for three of these methods, the results on both Chem 1 analysers are biased in slope and intercept, and corrections of these parameters are necessary to produce results comparable to the reference method values. For the remaining eighteen assays, methods in routine use in our laboratory were used as comparison methods. In fifteen of eighteen assays, corrections of slope and (or) intercept were necessary to prevent changes in the cumulative average patient data produced by our laboratory. An adjustment of the slopes and intercepts, according to the multi-point calibration procedure presented here, resulted in significant differences between system-specific values measured in our laboratory and those assigned by the manufacturer for ten of thirteen methods. We conclude that the use of the multi-point calibration procedure presented in this article (based on calibration according to the instructions of the manufacturer and NCCLS EP-9P) greatly improves the intra-laboratory comparability and therefore should be part of multi-centre evaluations.

Autoanalysis↗
PubMed1990

[Results of various analysis technics in relation to urinary calculi studies].

The article describes the results of surveys on renal calculi analysis organised by the Dutch Quality Assessment Foundation (SKZL) over the years 1986-1989. Most of the Dutch laboratories apply wet chemistry, some of them infrared spectroscopy, some polarisation microscopy and one X-ray diffraction analysis. The results of the wet chemistry category are poor, the infrared spectroscopy and the polarisation microscopy group score moderately well while the X-ray diffraction analysis laboratory performs well. On the basis of the results it is suggested to promote the physical chemical methods for renal calculi analysis.

Humans↗
PubMed1990

Experiences with a new assay for pancreas specific alpha-amylase.

The evaluation of an enzymatic colorimetric method to measure pancreas amylase activity in serum using two monoclonal antibodies that specifically inhibit salivary amylase is described. The assay is quick, easy to perform and can be automated easily. Within-run and day-to-day precision studies gave CVs of less than or equal to 1.5 p. cent and less than or equal to 2.6 p. cent respectively. The test is linear up to 2,150 U/L. Salivary amylase activities up to 20,000 U/L did not contribute more than 2 p. cent to pancreatic amylase activity present in a serum sample. A significant interference by bilirubin is found. Reference values were established for both pancreatic and total amylase activities in serum and used for interpreting the results of pancreatic amylase and total amylase in 72 randomly selected patients. Results obtained by this method agree well with a lectin inhibition method (r = 0.9886).

Acute Disease↗
PubMed1989

[The effect of immunoscintigraphy with monoclonal antibodies on assays of hormones and tumor markers. This is not the end of the matter!].

The use of monoclonal antibodies in medicine for in-vivo diagnostic methods and for therapeutic purposes will increase in the future. Although monoclonal antibodies possess a high specificity, the animal origin of these antibodies remains a problem. Repeated administration of animal monoclonal antibodies (in vivo) may induce the formation of human antibodies against these monoclonal antibodies. Because animal monoclonal antibodies are also used in laboratory assays (in vitro), the presence of human antibodies against these animal monoclonal antibodies may cause spuriously elevated or depressed results of these assays. The clinician should be alert to this possibility. A case history is presented to demonstrate the problem.

Aged↗
PubMed1989

Xanthochromia after subarachnoid haemorrhage needs no revisitation.

Recently it was contended that it is bloodstained cerebrospinal fluid (CSF) that is important in the diagnosis of subarachnoid haemorrhage (SAH) and not xanthochromia, and also that a normal CT scan and the absence of xanthochromia in the CSF do not exclude a ruptured intracranial aneurysm. The CSF findings were therefore reviewed of 111 patients with a proven SAH. All patients had xanthochromia of the CSF. Lumbar punctures were performed between 12 hours and one week after the ictus. Xanthochromia was still present in all (41) patients after 1 week, in all (32) patients after 2 weeks, in 20 of 22 patients after three weeks and in 10 of 14 patients after four weeks. In six years we identified only 12 patients with sudden headache, normal CT, bloodstained CSF, and no xanthochromia. Angiography was carried out in three and was negative. All 12 patients survived without disability and were not re-admitted with a SAH (mean follow up 4 years). It is concluded that it is still xanthochromia that is important in the diagnosis of SAH and not bloodstained CSF. Furthermore a normal CT scan and the absence of xanthochromia do exclude a ruptured aneurysm, provided xanthochromia is investigated by spectrophotometry and lumbar puncture is carried out between 12 hours and 2 weeks after the ictus.

Humans↗
PubMed1989

European multicentre evaluation of the ABBOTT Spectrum clinical chemistry analyzer.

The analytical performance of the selective multitest ABBOTT Spectrum analyser was studied according to the ECCLS guidelines and partly the CERMAB protocol in a multicentre evaluation involving laboratories from six European countries. Fifteen analytes, including the electrolytes sodium, potassium and chloride, were measured each in at least 3 laboratories, all at 37 degrees C, except the electrolytes, which are measured at room temperature. The trial lasted approximately three months and involved the collection of over 60,000 data points. It yielded the following results: 1. The precision was at least as good as the precision obtained with the comparison instruments. The majority of the coefficients of variation were between 1 and 4%. 2. The recovery for method assigned control sera values was, with few exceptions, within 10%. 3. Good agreement with respect to the method assigned values of control materials and method comparison with patient specimens to different instruments (e.g. SMAC, Hitachi 737, RA 1000) was found. 4. No drift was observed. 5. Reagent-related carry-over was not found. Specimen-related carry-over was detected in some cases, the deviation being of little or no clinical significance. 6. The manufacturer's claims regarding method linearity were as stated or exceeded. 7. The open system capability was tested and rated as very convenient. 8. The practicability of the instrument was very good.

Blood Chemical Analysis↗
PubMed1989

An evaluation of the improved Technicon Chem 1 system.

The improved selective multitest analyser Technicon Chem 1 was evaluated according to the ECCLS guidelines in our laboratory. Twenty two routine parameters were examined. The trial also included a clinical evaluation. About 50,000 measurements were performed during six weeks. The following conclusions can be drawn: 1. The changes made in the system (mainly software) led to genuine improvements. 2. The precision of the system can be rated as good. With a few exceptions (alkaline phosphatase, lactate dehydrogenase, creatine kinase, albumin and total bilirubin) all between-day coefficients of variation are lower than 3%. 3. Excellent agreement was found between the results obtained from the Chem 1 and from the comparison methods. 4. No drift was observed. Once calibrated the Chem 1 can be used for at least fifteen days without renewed calibration, except for the analysis of sodium, potassium and calcium. 5. No carry-over was observed, either specimen-related, or reagent-related. 6. Though not all methods were examined in detail, in general the linearity was found to agree with the manufacturer's claims. 7. The influence of interfering substances proved to be moderate. 8. The practicability of the system was good. A more complete judgement is given in the Discussion Section.

Blood Chemical Analysis↗
PubMed1988

Measurement of total serum protein by near-infrared reflectance spectroscopy.

This study describes the measurement of total protein in serum by near-infrared reflectance spectroscopy. With an algorithm, generated by the calibration procedure, the protein content of serum samples was calculated from absorbance data at various wavelengths in the near-infrared. A good correlation (r = 0.993) was found between near-infrared reflectance spectroscopy measurement of serum protein and analysis by the biuret reaction.

Blood Proteins↗
PubMed1987

Further studies on the standardization of neonatal bilirubin.

Certain problems in the standardization of direct-reading instruments (bilirubinometers) were investigated. It was shown that the combination of wavelength setting and choice of pH is very important with respect to the standard to be used. It is emphasized that in fact there is no synthetic bilirubin standard which can be used as primary standard. Reasons are given why the only pragmentic solution proved to be a pool of neonatal serum.

Adult↗