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R R Friis

Publications and source records attributed to R R Friis.

96 records · Page 6Linked to original sources
PubMedDate not supplied

Release of a mitogenic factor by adult rat lung slices in culture.

In an effort to develop a suitable bioassay for testing lung growth factors that might be operative during compensatory lung growth following partial pneumonectomy, a simple and inexpensive lung organ culture system was characterized. The culture employs lung tissue slices obtained by means of a device allowing thicknesses of 500 microns to be cut reproducibly. To avoid the collapse of the organ, the alveolar spaces were filled prior to culture with Noble agar-containing Eagle's-Dulbecco's modified medium. Lung tissue sections could be maintained ultrastructurally intact for at least one week. The results showed that upon culture, a part of the type II pneumocytes undergo differentiation into type I pneumocytes, thus demonstrating that the culture system may be suited for differentiation studies. One surprising feature of this culture system was the mitogenic impulse associated with culture. Radioactively labeled thymidine incorporation was strongly stimulated in the culture, mainly affecting the epithelial cells, as could be established by "back-to-back" autoradiography. With a reconstruction experiment, it was possible to demonstrate the local release of a mitogenic factor following slicing, mincing, or dissection of the lung tissue, which could be assayed by its ability to induce serum-starved Balb/c 3T3 cells to synthesize DNA in culture.

3T3 Cells↗
PubMedDate not supplied

Energy metabolism in the involuting mammary gland.

A strong and coordinated upregulation of the glycolytic, glutaminolytic and pentose phosphate pathway enzymes occurs during the onset of lactation in the normal mouse mammary gland. Induction of apoptosis by removing the pups led to an inactivation of the same enzymes with different time courses. While the ATP-consuming glycolytic 6-phosphofructo 1-kinase and mitochondrial bound hexokinase still remained high on days one and two of involution, the ATP-regenerating pyruvate kinase was immediately reduced. The enzymes of the pentose phosphate and glutaminolytic pathway were inactivated on the first two days of involution. In accordance with such an inactivation of the enzymes ATP, GTP, UTP, ADP, NAD NADH and lactate concentrations decreased. The synthetic product of UTP, UDP-N-acetylglucosamine, increased. AMP was found in the milk, not in the epithelial cells. The inactivation of the enzymes was caused by partial proteolysis or by a loss of the intact proteins from the cytosol without signs of proteolysis.

Animals↗