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Biomedical subjects

K Linnet

Publications and source records attributed to K Linnet.

At least 73 records · Page 4Linked to original sources
PubMed1985

Analysis of insulin receptors on heterogeneous eukaryotic cell populations with fluorochrome-conjugated insulin and fluorescence-activated cell sorter. Advantages and limitations to the 125I-labelled insulin methodology.

The diversity in insulin receptor expression within eukaryotic cell populations can be studied with fluorochrome conjugated reagents with high affinity to the insulin receptor in combination with flow cytometry. We studied the optimal conditions for application of fluorescein isothiocyanate (FITC) conjugated insulin in combination with the fluorescence activated cell sorter (FACS) to analyse insulin receptor expression, and also studied the feasibility of this method for identifying and isolating viable subsets with differences in insulin receptor expression within a cell population. Semisynthetic human insulin was conjugated to FITC, which resulted in at least four types of FITC-insulin molecules with different affinities to the insulin receptor. Each type of FITC-insulin was isolated by semipreparative reverse phase high pressure liquid chromatography. The preparation with a fluorescein/protein ratio of approximately 1.0 was found to have the highest affinity to the receptor, the highest biological activity (approximately 50% of native insulin), and similar antigenicity as native insulin. The optimal staining conditions with respect to pH, time of incubation, and cell number were determined, and were different in some aspects from labelling with 125I-insulin. The binding of FITC-insulin to cells was saturable and could be displaced with unlabelled insulin. The fluorescence signal could be converted to absolute numbers of fluorescein molecules by a calibration curve, and the absolute number of specifically bound FITC-insulin molecules calculated from a F/P ratio approximately 1.0. The FITC-insulin/FACS method permits estimation of the total number of insulin receptors (high plus low affinity), and the data obtained correlate well with the results from Scatchard plot of 125I-insulin binding data.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Precision of sensitivity estimations in diagnostic test evaluations. Power functions for comparisons of sensitivities of two tests.

The precision of estimates of the sensitivity of diagnostic tests is evaluated. "Sensitivity" is defined as the fraction of diseased subjects with test values exceeding the 0.975-fractile of the distribution of control values. An estimate of the sensitivity is subject to sample variation because of variation of both control observations and patient observations. If gaussian distributions are assumed, the 0.95-confidence interval for a sensitivity estimate is up to +/- 0.15 for a sample of 100 controls and 100 patients. For the same sample size, minimum differences of 0.08 to 0.32 of sensitivities of two tests are established as significant with a power of 0.90. For some published diagnostic test evaluations the median sample sizes for controls and patients were 63 and 33, respectively. I show that, to obtain a reasonable precision of sensitivity estimates and a reasonable power when two tests are being compared, the number of samples should in general be considerably larger.

Clinical Laboratory Techniques↗
PubMed1984

Concentrations of glycine- and taurine-conjugated bile acids in portal and systemic venous serum in man.

Concentrations of glycine and taurine conjugates of cholic, chenodeoxycholic, and deoxycholic acid in portal and systemic venous serum and in bile were measured in eight subjects undergoing elective cholecystectomy. Mean concentrations in systemic serum ranged from 0.07 to 0.17 mumol/l, in portal serum from 0.49 to 2.09 mumol/l, and in bile from 2.72 to 17.2 mmol/l. The percentage content of trihydroxy-bile acid conjugates in bile (49%) and in portal serum (51%) was higher than in systemic serum (35%) (P less than 0.001). The estimated hepatic fractional uptake of glycocholic acid (mean, 83%) and of taurocholic acid (83%) was higher than the uptakes of the dihydroxy-bile acid conjugates (60-68%). The percentage contents of glycine-conjugated bile acids in systemic serum (mean, 66%), portal serum (62%), and bile (65%) were not significantly different.

Adult↗
PubMed1984

Cholecystokinin-stimulated and postprandial serum concentrations of bile acids in alcoholic liver cirrhosis.

This investigation was undertaken to examine the alterations in serum bile acid concentration after intravenous administration of cholecystokinin and a standard meal in 13 patients with alcoholic cirrhosis. Total 3 alpha-hydroxy bile acids in serum (SBA) were monitored for 2 h after injection of cholecystokinin and for 3 h after the standard meal. The median fasting value of SBA was 39.9 mumol/l (range, 3.2-148 mumol/l). The increase in SBA after cholecystokinin started earlier and lasted shorter than after standard meal stimulation (median, 30 min and 120 min, respectively). The appropriate relative peak levels of SBA were 173% and 212% of the fasting value. The increments were significant (P less than 0.01) within groups but insignificant between groups. Day-to-day variation of postprandial SBA was more pronounced than after cholecystokinin stimulation. The difference, however, was insignificant. An inverse correlation was detected between both fasting and stimulated peak levels of SBA and P-coagulation factors 2, 7, and 10.

Adult↗
PubMed1983

Differential diagnostic value in hepatobiliary disease of serum conjugated bile acid concentrations and some routine liver tests assessed by discriminant analysis.

Serum concentrations of glycine and taurine conjugates of cholic, chenodeoxycholic, and deoxycholic acid were measured with a HPLC-enzymatic assay in 104 patients with hepatobiliary diseases. The capability of discriminating between four major diagnostic categories by the serum bile acid concentrations, alone and in conjunction with five commonly used biochemical liver tests, was evaluated by stepwise linear discriminant analysis. The serum bile acid pattern alone was inferior to the routine liver tests in separating the diagnostic groups. When the two sets of analytes were combined, the generalized group distance (Rao's V) was significantly increased, showing that the serum bile acid pattern contained discriminatory information in addition to the routine liver tests. The gain in correct reclassification of patients obtained by adding the serum bile acids, however, was only marginal.

Adolescent↗
PubMed1983

Liver function under long-term treatment with neuroleptic drugs assessed by serum concentrations of bile acids, alkaline phosphatase, and aspartate aminotransferase.

Serum concentrations of total 3 alpha-hydroxy-bile acids, alkaline phosphatase, and aspartate aminotransferase were measured in 35 psychotic patients who had been under treatment with neuroleptic drugs for more than 1 year. Serum concentrations of total bile acids were from 1.0 to 9.4 mumol/l (mean 2.9 mumol/l) in the patients and from 0.6 to 4.8 mumol/l (mean 2.2 mumol/l) in 20 healthy controls; the mean values were not significantly different. Serum concentrations of alkaline phosphatase and aspartate aminotransferase in patients and controls were not significantly different either. In conclusion, none of the patients had signs of manifest hepatobiliary dysfunction.

Adolescent↗
PubMed1983

Postprandial plasma concentrations of glycine and taurine conjugated bile acids in healthy subjects.

Fasting and postprandial plasma concentrations of glycine and taurine conjugates of cholic, chenodeoxycholic, and deoxycholic acid were measured by a high pressure liquid chromatography-enzymatic assay in nine healthy subjects. The mean value of each bile acid concentration increased significantly (2.4-4.7 times) in the postprandial period. The total glycine taurine ratio of 2.5 in the fasting state increased significantly to a maximum value of 3.3 at one to 1 1/2 hours postprandially and then declined. This shift in glycine taurine ratio shows, that the relative increase in concentrations of glycine conjugates exceeds the relative increase in concentrations of taurine conjugates in the early postprandial period, and supports the view that there is significant absorption of glycine conjugated bile acids from the proximal small intestine.

Adolescent↗
PubMed1983

Diagnostic values of fasting and postprandial concentrations in serum of 3 alpha-hydroxy-bile acids and gamma-glutamyl transferase in hepatobiliary disease.

Fasting and postprandial concentrations in serum of 3 alpha-hydroxy-bile acids and gamma-glutamyl transferase were measured in 138 consecutive patients, 62 with (D) and 76 without (D) hepatobiliary disease. The maximum efficiencies of the three tests--that is, the fractions of patients allocated correctly to the D or D group at the optimum discrimination values--were 0.85, 0.84, and 0.83, respectively. Furthermore, the predictive values and nosographic sensitivities and specificities were rather similar. When the three tests were combined, the nosographic sensitivity increased significantly to a value of 0.84, and the corresponding specificity was 0.91. The diagnostic value of the absolute postprandial increase in serum bile acid concentration was slightly inferior to the diagnostic values of the fasting and postprandial serum bile acid concentrations and, finally, the relative postprandial serum bile acid increase was of no diagnostic value at all.

Adolescent↗
PubMed1983

Fasting and postprandial serum concentrations of glycine- and taurine-conjugated bile acids in Crohn's disease.

Fasting and postprandial serum concentrations of glycine and taurine conjugates of cholic, chenodeoxycholic, and deoxycholic acid were measured with a high-pressure liquid chromatographic-enzymatic assay in 17 patients with ileal Crohn's disease and in 17 controls. The postprandial concentrations of the taurine-conjugated bile acids in the patients were significantly lower than in the controls, whereas the concentrations of the glycine conjugates were not significantly different. The total glycine to taurine ratios of serum bile acids were significantly higher in the patients (means, 2.9 fasting and 4.8 postprandial) than in the controls (1.9 and 2.6). Of the patients, 65% had a postprandial total G/T ratio of serum bile acids which was above the control interval.

Adult↗
PubMed1982

The patterns of glycine and taurine conjugates of bile acids in serum in hepatobiliary disease.

Fasting serum concentrations of glycine and taurine conjugates of cholic, chenodeoxycholic, and deoxycholic acid were measured with a high-pressure liquid chromatography-enzymatic assay in patients with hepatobiliary disease. The total glycine to taurine ratio was significantly lower in extrahepatic cholestasis (median 1.1) than in cirrhosis (median, 2.0) and controls (median, 1.7). In patients with cirrhosis the ratio was significantly correlated with the S-bilirubins, P-coagulation factors (II + VII + X), and S-total conjugated bile acids. Because of large overlaps of the ratio between the groups the glycine to taurine ratio is of hardly any diagnostic value. The ratio of cholic acid conjugates to chenodeoxycholic acid conjugates was over 1.5 in 10 of 12 cholestasis patients and below this value in all but 1 patient with cirrhosis; the separation of the groups was not improved by splitting the ratio in glycine and taurine conjugates. This study does not suggest that separate determination of glycine and taurine conjugates of bile acids in serum adds diagnostic information in hepatobiliary disease.

Adult↗
PubMed1982

Predictive value of the concentration in serum of total 3 alpha-hydroxy bile acids in the diagnosis of hepatobiliary disease.

Fasting serum levels of total 3 alpha-hydroxy bile acids were measured in 163 consecutive patients, who clinically were suspected of having a hepatobiliary disorder. By means of routine biochemical liver tests and paraclinical investigations the clinical suspicion was confirmed in 95 patients and disproved in the other 68 patients. A comparison between this diagnostic grouping and the serum bile acids levels showed that the predictive value of serum concentrations above a discrimination value of 10 mumol/l--that is, the predictive value of a positive test--was 1.0 (0.94-1.0), whereas the corresponding predictive value of a negative test was 0.66 (0.56-0.75). Thus, fasting serum levels of total 3 alpha-hydroxy bile acids may be used as a highly specific and moderately sensitive diagnostic test for hepatobiliary disorders. Furthermore, the study showed that the nosographic sensitivity of total 3 alpha-hydroxy bile acids in patients with verified cirrhosis was significantly greater than that of serum bilirubins and not significantly different from those of the other routine biochemical liver tests.

Adult↗