[Metaanalysis of reference values in hematology]. / Referenzbereiche in der Hämatologie.

The reference values of the most commonly used parameters in hematology were evaluated in a metaanalysis using practices of a group of major hospitals in Switzerland and in detail review of the literature. Extensive differences of the reference values have been noted being caused mainly by selection of different patient/control collectives. Whenever possible, reference values were separately evaluated for age, gender and race. The reported reference values approximated a Gauss distribution allowing for statistical evaluation accordingly. Due to recent standardization (ICSH and NCCLS), differences caused by instrumentation and preanalytics were found to be of less importance. Our presented validated reference values in hematology should allow for better discrimination of classical hematological disease entities such as an iron deficiency anemia, thalassemia and hemolysis.

[Standardized counting of particles in the urine: a comparison between flow cytometry, cell chamber counting and traditional sediment analysis]. / Standardisierte Partikelzählung im Urin: Ein Vergleich zwischen Durchfluss-Zytometrie, Zählkammer und traditionellem Urinsediment.

We compared the number of particles in the urine with flow cytometry and manual methods: cell chamber and standardised sediment analysis. The correlation (r) between the KOVA-cell chamber and the flow cytometer UF-100 was 0.966 for erythrocytes, 0.935 for leukocytes and 0.902 for squamous epithelial cells. Similar results were obtained by a standardised preparation of the sediment. Today, the estimation of the cell number in the sediment analysis is still common. The KOVA cell chamber system is a cheap alternative for microscopy, whereas automation with flow cytometry is only used for large laboratories. Reference values were established under optimal conditions (erythrocytes < 14/microliter, leukocytes < 16/microliter) with a cut-off of 20/microliter.

Immobilized artificial membrane (IAM)-HPLC for partition studies of neutral and ionized acids and bases in comparison with the liposomal partition system.

PURPOSE: To study the partitioning of model acids ((RS)-warfarin and salicylic acid), and bases (lidocaine, (RS)-propranolol and diazepam), with immobilized artificial membrane (IAM)-HPLC, as compared to partitioning in the standardized phosphatidylcholine liposome/buffer system. METHODS: The pH-dependent apparent partition coefficients D were calculated from capacity factors (k'IAM) obtained by IAM-HPLC, using a 11-carboxylundecylphosphocholine column. For lipophilic compounds k'IAM, values were determined with organic modifiers and extrapolation to 100% water phase (k'IAMw) was optimized. Temperature dependence was explored (23 to 45 degrees C), and Gibbs free energy (deltaG), partial molar enthalpy (deltaH) and change in entropy (deltaS) were calculated. Equilibrium dialysis was used for the partitioning studies with the liposome/buffer system. RESULTS: For extrapolation of k'IAMw, linear plots were obtained both with the respective dielectric constants and the mole fractions of the organic modifier. All tested compounds showed a similar pH-D diagram in both systems; however, significant differences were reproducibly found in the pH range of 5 to 8. In all cases, deltaG and deltaH were negative, whereas deltaS values were negative for acids and positive for bases. CONCLUSIONS: In both partitioning systems, D values decreased significantly with the change from the neutral to the charged ionization state of the solute. The differences found under physiological conditions, i.e. around pH 7.4, were attributed to nonspecific interactions of the drug with the silica surface of the IAM column.

Structure-permeation relations of met-enkephalin peptide analogues on absorption and secretion mechanisms in Caco-2 monolayers.

Due to the low effective permeabilities of peptides at many absorption sites, their structure-permeation relations are of high interest. In this work structure-permeation relations of Met-enkephalin analogues are presented using confluent Caco-2 cells as an in vitro permeation model. Four model peptides (Met-enkephalin, [D-Ala2]Met-enkephalin, [D-Ala2]Met-enkephalinamide, and metkephamid) were tested in terms of permeability, lipophilicity, charge, and molecular size. Permeability coefficients (P(eff)) across Caco-2 cells were low, 3.3 x 10(-8) to 9.5 x 10(-8) cm s-1, and were similar to typical paracellular markers. No correlation of permeability and the log(apparent octanol/buffer partition coefficient) was observed. A 40-fold increase of the permeability of metkephamid in the presence of 10 mM EDTA suggested a significant contribution of paracellular transport. Independent support for this conclusion was obtained by visualizing the pathway of the fluorescein isocyanate isomer I 1-metkephamid by confocal laser scanning microscopy (CLSM). The fluorophore-labeled peptide was observed in the intercallular space only. Metkephamid permeabilities were found to be direction-specific. Permeabilities from basolateral to apical (b-to-a) were significantly higher (ca. 4-fold) than in the opposite (a-to-b) direction. The addition of verapamil equalized the permeabilities in the a-to-b and b-to-a directions, suggesting the involvement of a P-glycoprotein-mediated secretion mechanism. Similar observations were obtained with [D-Ala2]Met-enkephalinamide, but not with Met-enkephalin and [D-Ala2]Met-enkephalin. In contrast to the other analogues, metkephamid and [D-Ala2]Met-enkephalinamide are positively charged at neutral pH, as demonstrated by their isoelectric points (pl = 8.6 for [D-Ala2]Met-enkephalinamide and metkephamid and 5.3 for [D-Ala2]Met-enkephalin and Met-enkephalin). The data is in agreement with the literature showing that most compounds secreted by the P-glycoprotein transporter carry a positive charge.

Pharmacokinetic properties and interactions with blood components of N4-hexadecyl-1-beta-D-arabinofuranosylcytosine (NHAC) incorporated into liposomes.

N4-Hexadecyl-1-beta-D-arabinofuranosylcytosine (NHAC) is a new lipophilic derivative of 1-beta-D-arabinofuranosylcytosine (ara-C) with strong antitumour activity. The interactions of NHAC incorporated into small unilamellar liposomes of different compositions with blood components were evaluated. In comparison with ara-C, NHAC is highly protected against deamination to inactive arabinofuranosyluracil (ara-U) in human plasma, resulting in only 2% conversion into ara-U after 4 h incubation at 37 degrees C, whereas from ara-C more than 80% was deaminated. In in-vitro incubations with human blood, it was found that NHAC was transferred from the liposomes at about 47% efficiency to plasma proteins, particularly to albumin and to the high and low density lipoproteins. The remaining part of NHAC was bound to erythrocytes (50%) and to leucocytes (3%). The addition of poly(ethylene) glycol-modified phospholipids to the liposomes (PEG liposomes), which were composed of soy phosphatidylcholine and cholesterol (plain liposomes), did not significantly prevent the fast transfer of NHAC from the liposomes to the blood components. Pharmacokinetic studies in mice revealed that NHAC had biphasic kinetics in blood with a t1/2 alpha of 16 min and a t1/2 beta of 3.8 h when the drug was formulated in plain liposomes and a t1/2 alpha of 15 min and a t1/2 beta of 9.67 h in PEG liposomes, respectively. NHAC was predominantly distributed in the liver with 29% of the injected dose found after 30 min.(ABSTRACT TRUNCATED AT 250 WORDS)