Initially polypeptide hormones were assayed by their biological activity. Such conventional bioassays, however, are remarkably insensitive. For example, the Lipscomb and Nelson (1962) bioassay of corticotrophin (ACTH) cannot measure a concentration of less than about 100 pg/ml, while the normal circulating levels of the bioactive form of this hormone range from about 5 to 60 pg/ml. The introduc...

The effect of avidin-biotin interactions in several detection systems for the non-radioactive in situ hybridization (ISH) technique was studied in a model system using a transitional cell carcinoma line and a biotinylated DNA probe. We performed fluorescence ISH to unravel the individual steps in a sensitive and frequently used amplification method which makes use of the alternating cytochemica...

Intraobserver and interobserver reproducibility of the FAB classification was assessed for two independent observers whose decisions are acted on for treatment of patients with acute leukemia in the Hamilton region. Intraobserver reproducibility was assessed for Wright-stained preparations that were examined independently on two consecutive occasions at least 2 weeks apart. A third reading was ...

The intracellular distribution and level of acid hydrolases in Ochromonas malhamensis were studied in cells grown osmotrophically in a defined medium, in a carbon-free starvation medium, and during phagotrophy in each of these media. By cytochemical techniques, little enzymic reaction product was observed in the vacuoles of osmotrophic cells grown in the defined medium. Starved cells, however, ...

The striking difference in the cytochemical pattern of acid esterase between blood monocytes and T lymphocytes initiated the present study to determine whether or not the cytochemical difference is related to a cell-specific polymorphism of the isoenzymes. Enzyme assays and isoelectric focusing were performed using detergent-treated lysosomes from viable monocytes, granulocytes. T lymphocytes, ...

The ultrastructural morphology of human placental and mouse placental nematosomes has been investigated. The description includes a three-dimensional analysis of the shape of the organelles based on serial sectioning, measurements of the repeat distance of the subunit fibre of the organelle derived by optical diffraction analysis and the results of an ultrastructural cytochemical study designed...

We present 2 cases of Niemann Pick disease, type B with secondary sea-blue histiocytosis. Strikingly, in both cases the Pick cells were positive for tartrate resistant acid phosphatase, a finding hitherto described only in Gaucher cells. This report highlights the importance of this finding as a potential cytochemical diagnostic pitfall in the diagnosis of Niemann Pick disease.

Dr. Antonino Carbone, Division of Pathology, Centro di Riferimento Oncologico, Via Pedemontana Occidentale, I-33081 Aviano (Italy) The cytochemical demonstration of dipeptidyl amino peptidase IV (DAP IV) in human peripheral blood lymphocytes was first described by Lojda [1]. Subsequent reports have shown that this ‘exopepti-dase’ has an apparent restriction to a particular T-cell subset, in tha...