The enhancement of hepatic nucleolar RNA synthesis induced by Cr(III) in partially hepatectomized rats and its mechanisms are described. Cr(III)-administered (0.5 mg Cr/kg, ip) and then partially hepatectomized rats were significantly enhanced in the hepatic nucleolar RNA synthesis at the very early stage of liver regeneration. This enhancement was caused both by the induction of newly found nucleolar Cr-bound protein of 70 kD (Cr-p70) and by the activation of nucleolar chromatin, both of which arose from nuclear accumulation of Cr together with partial hepatectomy. Studies on the mechanism of this enhancement indicated that the Cr-p70 bound to the activated nucleolar chromatin and loosened its higher-order structure, resulting in an increase of the B-form fraction of chromatin DNA. The degree of this loosening well correlated with the amount of Cr-p70 bound to chromatin and also with the extent of elevation of RNA synthesis. Some molecular species of nonhistone proteins in chromatin were found to play an important role in the interaction to Cr-p70. These results suggest a possibility that the action of Cr is involved in cell proliferation process.

Animals↗

PubMedDate not supplied

Simultaneous demonstration of infecting fungi and DNA-synthesizing epithelial cells in the skin.

An excellent staining method to demonstrate in vivo dermatophytes and DNA-synthesizing cells in the skin is described. Deparaffinized sections of guinea pig skin, infected with dermatophytes and given bromodeoxyuridine (BrdU) by intraperitoneal injection, were used. Periodic acid-Schiff (PAS) stain in combination with an immunohistochemical stain using anti-BrdU monoclonal antibody allowed simultaneous visualization of fungi and DNA-synthesizing epithelial cells in the skin. Many epithelial cells near the infecting fungi in follicles and interfollicular skin were labelled with BrdU. Only a few BrdU-positive cells were observed in the skin of uninfected animals.

Animals↗

PubMedDate not supplied

Determination of pyrimethamine in animal tissue and egg by liquid chromatography with fluorescence detection.

A sensitive and selective liquid chromatographic (LC) assay was developed to determine the concentration of pyrimethamine in animal tissue and egg by fluorescent derivative. Animal samples were extracted with acetonitrile, centrifuged, and purified by hexane. Fluorescent derivatization was performed by reacting pyrimethamine with chloroacetaldehyde and subjected to LC with fluorescence detection (excitation wavelength 300 nm, emission wavelength 420 nm). The limit of detection was 10 ng/g (10 ppb) and the standard calibration curve was linear in the range of 1-100 ppb (0.01-1 ng/10 microL). Recoveries from samples fortified at levels of 0.1 and 1 ppm (microg/g) were 61.0-77.4 and 65.5-81.2%, respectively. The method was applied to the monitoring of marketed samples. Pyrimethamine was not determined in any of the 70 samples: 20 swine muscle; 20 chicken muscle; 10 chicken liver; and 20 egg.

Animals↗