Type IV collagenase (gelatinase) is a 70,000 dalton neutral metalloproteinase that specifically cleaves type IV collagen in addition to degrading denatured collagen (gelatin). It is secreted in a latent proenzyme form that is converted proteolytically in the extracellular space to a 62,000 dalton active enzyme. The primary structure, enzymatic properties as well as gene structure, demonstrate that type IV collagenase is closely related with the other well characterized metalloproteinases, interstitial collagenase and stromelysin. However, the structure of type IV collagenase differs from the others in that it is larger and contains three internal repeats that resemble the type II domains of fibronectin. Also, initial characterization of the promoter region of the gene indicates that its regulation differs from the other proteinase genes. Type IV collagenase is presumably required for the normal turnover of basement membranes. Augmented activity is linked with the invasive potential of tumor cells and the enzyme is believed to play a major role in the penetration of basement membranes by metastatic cells. Measurements of enzyme activity and mRNA levels as well as immunostaining of a variety of tumor cells and tissues suggest that assays for the enzyme may have value in the follow-up of malignant growth.
Hans Christian Geelmuyden (1861-1945) was amanuensis (assistant professor) at the Institute of Physiology, University of Oslo from 1889 to 1931. In 1897 he was awarded the degree "Doctor of Medicine" for his thesis "Om aceton som stofvexelprodukt" (On acetone as a metabolic product). The Nobel laureate Feodor Lynen referred to this thesis, which was also published in German, stating that Geelmuyden was the first to establish that ketone bodies are formed from fatty acids. Geelmuyden also established that acetone is metabolized in rabbits and dogs. Geelmuyden was a prolific writer on fat metabolism and diabetes and wrote a series of extensive reviews on these topics in Ergebnisse der Physiologie. Geelmuyden was active in the treatment of diabetic patients.
Formation of lactic acid by the extracts from the healthy rabbit muscles was studied as affected by the sera of embryos, newborn rabbits and pregnant female rabbits. The blood sera and beta-globulin isolated from them are established to activate anaerobic glycolysis and inhibit the Pasteur reaction. It is shown that protein typical of normal growth, belonging to beta-globulins and circulating in blood of the embryos, newborn rabbits from the first to the fifteenth day of development is "responsible" for this phenomena. Correlation is found between the precipitation test for detecting this protein and its biological effect on glycolysis and the Pasteur reaction.
The influence of ionizing irradiation (1, 2 and 4 Gy 137Cs) on both the activity of free-radical processes in plasma, formed elements and aorta wall as well as on the character of contractile vascular reactions of isolated rings of thoracic aorta and carotid artery in rabbits has been studied. The experiments were carried out on the 7th day after the whole-body irradiation. The results indicate that simultaneously with the weakening of antioxidant mechanisms both endothelium-dependent and endothelium-independent vascular wall relaxation slightly decreases after 1 Gy exposure. Noradrenaline and KCI-induced contraction is shown to increase. However, these changes are not statistically significant. Irradiation in dose of 2 and 4 Gy considerably decreases endothelium-dependent relaxation. Nitroglycerin-induced relaxation greatly diminishes, KCI- and noradrenaline-induced constriction considerably increases in these conditions. The level of activation of free-radical processes considerably increases too. Thus, already on the 7th day after irradiation significant changes in reactivity of vascular wall are developed. Radiation injures both endothelium and vascular smooth muscle cells. The free-radical processes seem to be the main cause of radiation vascular damage, so there is a pronounced correlation between the changes of vascular contractile properties and the degree of activation of these processes.
The developmental dynamics of pathologic changes in the lenses and activity of glutathione-S-transferase in the blood plasma, liver and lens tissues of rabbits under chronic influence (2 months) of small doses of X-ray radiation (total dose 2 Gy) and polychromatic light have been researched. It was shown, that polychromatic light and X-ray irradiation of rabbits significantly affected the lens nativity and increased the developmental frequency and the intensity of lens opacities. It was determined, that activity of glutathione-S-transferase in blood plasma increased for 1 month after the beginning of X-ray effects. The same effect on the enzymatic activity was shown by the summary influence of polychromatic light and X-ray irradiation. Glutathione-S-transferase activity decreased during 2 months as compared with the initial values, before irradiation of the animals. The enzymatic activity was increased in rabbit-liver cytoplasm by X-ray irradiation in 2 months. A decrease of glutathione-S-transferase activity in the liver, cortex and lens nucleus was determined under the influence of both X-ray radiation and polychromatic light.