[Thin-layer chromatographic determination of pyrantel in cow's milk and blood serum after oral administration of Banminth]. / Dünnschichromatographische Bestimmung von Pyrantel in Kuhmilch und Blutserum nach peroraler Applikation von Banminth.

After oral administration of the anthelmintic Banminth to cows the effective agent pyrantel appeared unchanged in blood serum and milk. After a therapeutic dose of 12,1 mg pyrantel tartrate/kg body weight, a maximum level of 8-9 micrograms/l could be found in milk 0-24 h after the application; the highest concentration of 22 micrograms/l in blood serum appeared after 10 h and the half-life time of elimination was ca. 15 h. Pyrantel determination in milk and blood serum was performed by quantitative thin layer chromatography. Positive results could be verified by HPLC.

Electron microscopy of rapidly frozen lungs: evaluation on the basis of standard criteria.

In recent years there has been a debate about the validity of the various methods for fixing lung tissue for electron microscopy in a state that faithfully reflects the physiological conditions prevailing at the time of fixation. Mazzone et al. (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 45: 325-333, 1978) introduced a method of rapid freezing followed by freeze-substitution fixation and found good preservation of fine structure; they claimed this method to be superior to others because it allowed careful control of physiological conditions. We have tested the suitability of this method for morphometric studies, where random sampling requires homogeneity of tissue preservation. The results are discussed on the basis of some standard criteria for the faithfulness of structural preservation. In terms of external standards, it was confirmed that one can find parts of the lung tissue samples to show a picture that is compatible with the established equivalent image of eucaryotic cells and tissues; however, the structure of blood was poorly preserved. In terms of the internal standards the method was found to yield inconsistent results; the specimens showed a wide spectrum of images of alveolar septa and capillaries, with "good preservation" limited to a very narrow area; furthermore, the method has a low level of reproducibility. We conclude that for the lung the method of freeze-substitution fixation is not suitable for morphometric work.

Identification of immunoreactive sites in bovine parathyroid cells to antibodies raised against the NH2-terminal sequence of parathyroid hormone.

The NH2-terminal sequence of bovine parathyroid hormone (1-84) was localized with different immunocytochemical methods on the light and electron microscopic level in bovine parathyroid glands and in isolated bovine parathyroid parenchymal cells. The peroxidase labeled staphylococcal protein A and the peroxidase anti-peroxidase method were found to be advantageous for light and electron microscopic localization, respectively. Reaction product was found light microscopically in the cytoplasma of the parenchymal cells and electron microscopically largely over the secretion granules of the parenchymal cells. The immunoreactive sites were subsequently identified to represent only intact parathyroid hormone (1-84) by gel electrophoresis derived enzyme linked immunosorbent assay.