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J Kropf

Publications and source records attributed to J Kropf.

36 records · Page 2Linked to original sources
PubMed1991

Time-resolved immunofluorometric assays with measurement of a europium chelate in solution: application for sensitive determination of fibronectin.

A novel detection principle applicable for sensitive measurement of molecules of biological interest by time-resolved fluorescence spectrophotometry is described. Our method is based on the quantification of the Eu3+ chelator 4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-dicarboxylic acid (BCPDA) in solution in presence of an excess of Eu3+ ions. BCPDA-labeled solid phase complexes obtained by conventional immunoassay procedures are transferred into solution using urea/SDS/Eu3+ as dissociating and fluorescent lanthanide ion reagent. Two 'sandwich-type' assay variants based on the above methodology were realized for the determination of small amounts of fibronectin (FN) in biological fluids. FN is captured from solution by solid phase coated gelatin or a monoclonal antibody, respectively. Rabbit anti-FN antiserum used as second antibody is detected with a biotinylated anti-rabbit IgG antibody. Fluoresence is measured after incubation with streptavidin-BCPDA and dissociation of solid phase complexes as described. Both assays have a detection limit (blank + 3 x SD) of less than 0.5 ng/ml FN, a dynamic range of up to 300 ng/ml, and intraserial coefficients of variation of 4.4 and 6.3%, respectively. Median FN concentrations in saliva of healthy individuals were 104 (gelatin) and 36 ng/ml (double antibody), respectively.

Chelating Agents↗
PubMed1991

Practical implications of coexistent different technologies in clinical chemical laboratories. Solid phase chemistry and conventional analysis.

If different analytical methods are alternatively used for the determination of the same analyte, basic differences in test methodology can give rise to an increased number of deviating results. Such coexistence of methods might be necessary, for example, during a transition phase while upgrading to new technologies. We have exemplarily investigated this topic for the comparison of solid phase chemistry ("dry chemistry") versus conventional methods ("wet chemistry"). The Kodak Ektachem 700XR clinical chemistry analyser was compared with the Hitachi 737 analyser from Boehringer Mannheim using 18 clinical chemical analytes and specimens submitted for routine analysis. Before the start of the evaluation, the Ektachem 700XR was adjusted ("calibrated") by the manufacturer for optimal agreement with the Hitachi 737. Satisfactory agreement was obtained for most investigated analytes as judged by correlation coefficients and three commonly applied regression methods (linear regression, principal components, and Passing/Bablok method). For some analytes, however, strongly deviating results were often obtained. Quality control-derived limits (maximum acceptable inaccuracy) and data from biological variation (critical differences) were used for the assessment of the inter-instrument bias for diagnosis and patient monitoring, respectively. For enzymes, 0% (amylase) to 22% (creatine kinase) of all pathologic results differed by more than the maximum acceptable analytical inaccuracy (21%-27%) of these analytes. If more stringent limits derived from biological variation were used, 24% (creatine kinase)--62% (aspartate aminotransferase) of all differences between paired measurements exceeded the critical difference for enzymes. Deviations greater than the critical differences were also marked for serum concentrations of sodium, calcium, and creatinine.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Chemical Analysis↗
PubMed1991

The prognostic value of extracellular matrix component concentrations in serum during treatment of adult respiratory distress syndrome with extracorporeal CO2 removal.

The time-dependent concentrations of hyaluronan, aminoterminal propeptide of type III procollagen, and laminin were determined in sera of 16 patients with severe adult respiratory distress syndrome during treatment with an extracorporeal CO2 removal device. Patients were classified according to lung parameters as responders (n = 10) and non-responders (n = 6) to extracorporeal CO2 removal. At the beginning of treatment strongly elevated serum concentrations of all studied extracellular matrix components were found. During the first 6-11 days of treatment the concentrations of aminoterminal propeptide of type III procollagen and hyaluronan increased further in non-responders but decreased in the majority of responders, while laminin decreased in both groups. No significant correlations were found between the serum concentrations of connective tissue components and the parameters of lung function. By non-parametric analysis of variance, significant differences between responders and non-responders according to treatment time could be established. By analysing the time course of the serum concentrations of hyaluronan and aminoterminal propeptide of type III procollagen, a total differentiation between responders and nonresponders was made possible by the trends of these analytes as early as three days after the start of treatment. The determination of aminoterminal propeptide of type III procollagen and hyaluronan in serum of patients with adult respiratory distress syndrome might therefore have prognostic significance in extracorporeal CO2 removal.

Adolescent↗
PubMed1991

Logistic-regression model for assessing portal hypertension by measuring hyaluronic acid (hyaluronan) and laminin in serum.

We earlier observed a positive correlation between portal venous pressure (PVP) and the concentration of laminin in serum. Here we investigated whether the diagnostic efficacy could be improved by considering additional analytes and application of multivariate statistical analysis. In 102 patients with fibrotic liver disease of various etiologies we measured PVP as the gradient of the wedged and free hepatic venous pressures and determined the concentrations of hyaluronic acid and laminin in serum. Regression coefficients established by logistic regression in this group were subsequently used to predict portal hypertension (PVP greater than mmHg) in an independent group of 45 patients. By comparison with the known PVP, we obtained a sensitivity of 0.83 (confidence interval: 0.63-0.93) and a specificity of 0.82 (0.61-0.93) for diagnosis of portal hypertension by means of the concentrations of hyaluronic acid and laminin in serum. Application of the model is suggested as a tool for pre-screening and monitoring patients to be subjected to assessment of portal hypertension.

Adult↗
PubMed1990

Follow-up of the serum levels of extracellular matrix components in acute and chronic pancreatitis.

Time-dependent serum concentrations of extracellular matrix proteins were studied in 32 patients with pancreatitis in order to find potential markers of the reparative response during the disease. Patients were subdivided by clinical and biochemical criteria: severe acute pancreatitis (n = 10), moderate acute pancreatitis (n = 17), and acute attack of chronic pancreatitis (n = 5). Serum and plasma samples were collected on days 1-7, 10, 14, and 21 for measurements of the aminoterminal propeptide of type III procollagen (PIIINP), hyaluronic acid, laminin, fibronectin, and routine clinical-chemical parameters. During an acute attack of chronic pancreatitis all parameters were within the reference range. In moderate acute pancreatitis concentrations of PIIINP, laminin, and hyaluronic acid fluctuated around the upper reference limit, but declined to mid-normal levels at day 21. In severe acute pancreatitis all three parameters increased. In patients who died as a consequence of sepsis and multi-organ failure the increase in PIIINP, laminin and hyaluronic acid was much more pronounced and paralleled by a decrease in plasma concentrations of fibronectin. In conclusion, this study revealed a relation between the severity of acute pancreatitis and the increase in serum concentrations of extracellular matrix components, especially PIIINP.

Acute Disease↗
PubMed1989

On the performance and reliability of mechanized urine teststrip measurement in comparison with visual reading.

Prescreening of urine specimens by teststrips is a valuable procedure for reducing the work load of the urine analysis laboratory: positive results for leukocytes, erythrocytes (haemoglobin), protein, and/or nitrite are widely used to select pathological specimens for subsequent microscopic examination. By standardization of the measurement conditions, mechanized teststrip reading is claimed to give more reproducible results than conventional techniques. To assess their ability to improve urine prescreening, especially with regard to the comparability of the results, the practical and analytical performance of three commercially available analysers (Rapimat II/T from Behringwerke AG, Urotron RL9 from Boehringer Mannheim GmbH, and Clinitek 200 from Ames/Bayer Diagnostic) was compared with visual reading. Analytical criteria were assessed using routine urine samples, while reproducibility was tested by repeated analysis of three different commercial control urines (Kova Trol from Madaus). A mean imprecision between 3% and 11.9% was found for the mechanized dipstick reading which was comparable to that found with visual examination (4.5% with Combur9-teststrips, Boehringer Mannheim GmbH). Due to the crude classification of the results, the different analysers as well as the visual technique gave quite different distributions for each of the semiquantitative parameters in the same urine samples. Even if statistical analysis was restricted to the frequency of positive results only, significant differences (chi 2-test, p less than 0.001-0.05) between methods were obtained, but these differences could not be attributed to one method alone. Using microscopic sediment analysis as reference, pathological urines were detected with a comparable sensitivity/specificity: Urotron 0.85/0.84, Rapimat 0.91/0.67, Clinitek 0.82/0.81, and duplicate visual reading 0.88/0.67 and 0.91/0.93. Mechanized teststrip reading had no obvious advantage with respect to the time required. We conclude: (i) no improvement in analytical performance or in speed of analysis could be claimed for mechanized methods in comparison with visual reading; (ii) mechanized teststrip reading might decrease the work load of the urine laboratory if integrated into a computerized laboratory system; (iii) mechanized teststrip reading will become analytically advantageous over visual reading if a more refined classification of the results is achieved.

Evaluation Studies as Topic↗
PubMed1988

Evaluation of serum aminoterminal procollagen type III propeptide as an index of portal hypertension and esophageal varices in chronic liver diseases.

The concentration of the aminoterminal propeptide of type III procollagen (P-III-P) was determined in serum of cubital vein and hepatic vein of patients with various types of chronic liver diseases (n = 111) and correlated with the portal venous pressure and with the degree of esophageal varices. The P-III-P level in all chronic liver diseases was correlated (rS 0.542, p less than 0.001) with the portal venous pressure, but in liver fibrotic subjects (n = 29) this correlation (rS 0.310) was not significant, in liver cirrhosis (n = 30) the respective correlation was found to be weak (rS 0.333, p less than 0.05) and similar to that in patients with unspecified chronic liver diseases (n = 52) (rS 0.425, p less than 0.01). Sensitivity and specificity of P-III-P at a cut-off concentration of 12 ng/ml for portal hypertension (portal vein pressure 5 mm Hg) are 0.93 and 0.42, respectively, the diagnostic efficiency is 0.67. Predictive values at the same cut-off level of P-III-P and an assumed prevalence of portal hypertension of 50% are 0.62 and 0.85 for the positive and negative test result, respectively. The level of P-III-P is not related to the degree of esophageal varices. The mean P-III-P concentration in the hepatic vein was found to be significantly (p less than 0.001) higher (about 35%) than that in the cubital vein. It is concluded that P-III-P is not an useful parameter for diagnosis of portal hypertension and monitoring of portal vein pressure and of the degree of esophageal varices.

Catheterization↗
PubMed1988

Efficacy of serum laminin measurement for diagnosis of fibrotic liver diseases.

We examined the efficacy of laminin assay in serum for diagnosis of fibrotic liver diseases. Values for subjects with liver disease significantly (P less than 0.05) exceeded those for healthy subjects and patients with nonhepatic diseases. At a cutoff value of 1.45 kilo-units(arb.)/L (approximately 330 micrograms/L) and an assumed prevalence of fibrotic liver diseases of 0.5, positive and negative predictive values of the test were 0.97 and 0.83, respectively, for the comparison with a healthy reference population and 0.81 and 0.80 for nonhepatic diseased patients. Increases in laminin concentration were positively correlated with the extent of fibrotic transition of the liver. Discrimination between fibrotic and cirrhotic stages of chronic liver diseases by means of laminin assay was better than with the amino-terminal propeptide of type III procollagen. According to the criteria of diagnostic efficacy, we conclude that determination of laminin in serum improves the possibilities of clinical-chemical diagnosis of liver fibrosis and cirrhosis. However, as commonly true for other biochemical tests, determination of laminin cannot replace conventional diagnostic methods.

Adolescent↗
PubMed1988

The predictive value of serum laminin for portal hypertension in chronic liver diseases.

The concentration of laminin, a high molecular weight basement membrane glycoprotein, was determined with a competitive radioimmunoassay in serum from the hepatic and cubital veins of patients with chronic liver diseases (n = 175), and correlated with portal venous pressure calculated from the hepatic vein pressure gradient. The level of laminin in the hepatic vein (mean value: 1.83 U/ml) was significantly (p less than 0.05) higher than that in the cubital vein (mean value 1.68 U/ml). In both vascular regions the glycoprotein levels increased with the degree of fibrosis, reaching their highest concentrations in cirrhosis (2.16 +/- 0.84 U/ml, p less than 0.001) (normal range: 0.81-1.43 U/ml). In all chronic liver diseases there was a significant positive correlation between the level of serum laminin and portal vein pressure (rs 0.70, p less than 0.001), which prompted us to calculate some criteria of the diagnostic validity of raised laminin for portal hypertension (portal venous pressure greater than or equal to 5 mm Hg). At a cut-off concentration of laminin of 1.45 U/ml, sensitivity is 0.87, specificity 0.74, diagnostic efficiency 0.81, and the likelihood ratio 3.4. Positive and negative predictive values at the same cut-off and at a prevalence of portal hypertension in this study of 50% are 0.77 and 0.85, respectively. Serum laminin may prove to be a potentially useful biochemical marker of portal hypertension.

Adult↗
PubMed1987

Estimation of the production rates of serum aminoterminal propeptide of type III procollagen and laminin in human fibrotic liver.

The concentrations of laminin, a high molecular weight non-collagenous glycoprotein of basement membranes, and of the N-terminal propeptide of type III procollagen were determined in the serum of the liver outflow vascular region (hepatic vein) and of a peripheral vein (cubital vein) in patients with chronic liver diseases (fibrosis, cirrhosis, unspecified histology; n = 173), in order to determine their secretion rates from the injured livers. The mean levels of laminin (1.84 kU/l) and of procollagen peptide (28.0 micrograms/l) in hepatic vein were significantly higher (about 9.5% at p less than 0.02, and 37% at p less than 0.001, respectively) than those in the periphery (1.68 kU/l and 20.4 micrograms/l, respectively). In chronic liver diseases, however, laminin and procollagen peptide concentrations in the hepatic vein were lower than or equal to those in the cubital vein in 18% and 27% of patients, respectively. The highest regional differences of the concentrations were noted in cirrhotic subjects. The serum levels of laminin (rs 0.93) and of procollagen peptide (rs 0.73) in hepatic and in cubital vein are highly positively correlated (p less than 0.001), but the levels of procollagen peptide in hepatic vein are only weakly but still significantly statistically related with those of laminin (rs 0.446, p less than 0.001). Similarly, the hepatic-cubital venous concentration differences of both proteins are weakly (rs 0.312) but significantly (p less than 0.001) correlated. On the basis of several assumptions we estimated secretion rates from the livers of 120 U.min-1 for laminin, and 5.7 micrograms.min-1 for procollagen peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic Disease↗
PubMedDate not supplied

CDTect-RIA and CDTect-EIA for determination of serum carbohydrate-deficient transferrin compared.

CDTect-RIA and CDTect-EIA for determination of serum carbohydrate-deficient transferrin (CDT) by radioimmunoassay and enzyme immunoassay respectively were tested for equality and precision in four European laboratories. For correlational studies, serum samples with CDT concentrations up to 130 U/l were analysed in accordance with a uniform trial schedule. The regression of CDT values obtained by the two procedures was computed for each laboratory using the method of Passing and Bablok. Slopes and intercepts of the regression functions did not differ significantly from the values 1 or 0, as proved by the corresponding 95% confidence intervals. Precision studies were computed using analysis of variance. For CDT concentrations at the upper reference limit for men, the within-day coefficients of variation (CVs) ranged between 0.7 and 6.4% (median 5.2%) for CDTect-RIA and from 4.3 to 9.2% (median 6.2%) for CDTect-EIA. The corresponding pure between-day CVs were 5.0-18.5% (median 9.8%) and 3.5-14.5% (median 10.9%). The study demonstrates the equality of CDT values obtained by CDTect-RIA and CDTect-EIA. According to this study, the two methods can be used interchangeably without getting fluctuating CDT values, e.g. in longitudinal studies.

Alcoholism↗
PubMedDate not supplied

The concentration pattern of laminin, hyaluronan, and aminoterminal propeptide of type III procollagen in seminal fluid.

The extracellular matrix components laminin, N-terminal propeptide of type III procollagen (PIIINP) and hyaluronan (HA) were determined in seminal fluids of 119 patients submitted for diagnosis of infertility. The concentrations of laminin and HA, but not those of PIIINP, were elevated in seminal fluid in comparison to their ranges of concentration in normal sera. Only weak correlations were observed between the concentrations of the three matrix components. The concentration of HA was negatively correlated with sperm count and ejaculate volume. Laminin was positively correlated with sperm count, the age of patients, and highly significantly with the concentrations of acrosin. A highly significant positive correlation was also found between PIIINP and fructose. By analysis of variance it could be shown that patients with azoospermia and oligozoospermia have significantly higher levels of HA than those with normospermia. Patients with terato- and asthenozoospermia showed no characteristic pattern of the matrix components.

Adult↗
PubMedDate not supplied

Laminin and aminoterminal propeptide of type III procollagen in seminal plasma from fertile and vasectomized men.

The components of the extracellular matrix, laminin and aminoterminal propeptide of type III procollagen (PIIINP) were determined in seminal plasma of 50 patients with vasectomy and of 50 age-matched fertile patients. The concentration of laminin was highly significantly (P < 0.001) elevated in the fertile group as compared to the vasectomy group, whereas the concentrations of PIIINP were not significantly different between these two groups. Only weak correlations were observed between the concentrations of laminin and PIIINP. It is suggested that part of the laminin found in seminal plasma is derived from the ductus deferens, while the source of PIIINP is probably located at an upper part of the urogenital tract.

Adult↗