Plasminogen activators in bovine milk during mastitis, an inflammatory disease

Interactions between bacteria type, proteolysis of casein and physico-chemical properties of bovine milk

“…The classical causes for accelerated PL activity in mammary secretion, namely, an increase in tissue-PA and/or rapid conversion of PLG to PL Politis, 1996) could not explain the increase in PL activity in the present study. Heegaard et al (1994) and Zachos, Politis, Gorewit, and Barbano (1992) found a large increase in PA activity in mastitic cows in correlation with an influx of PMNs. However, the leucocyte-related PA activity (mostly urokinase-type PA) was not detected in the present experiments because most of the leucocytes were discarded during the preparation of the samples and because urokinase-type PA is closely associated to the leucocytes through urokinase-type PA receptor (Politis, Bizelis, & Rogdakis, 2002;Politis, Zavizion, Cheli, & Baldi, 2002).…”

Effects of glandular bacterial infection and stage of lactation on milk clotting parameters: Comparison among cows, goats and sheep

“…This insight accounts for the coordination between the acute reductions in milk yield and milk quality in response to subclinical infection in the three species and the more acute response in sheep in comparison with goats and cows. The evolutionary physiological basis that underlies the reduction in milk clotting properties under conditions associated with milk stasis is prevention of formation of coagulates that might obstruct the evacuation of secretions from the mammary glands and thus, in turn, lead to complications such as necrosis and uncontrolled inflammation (Heegaard et al, 1994).…”

A Refined Kinetic Analysis of Plasminogen Activation by Recombinant Bovine Tissue-Type Plasminogen Activator Indicates Two Interconvertible Activator Forms

“…In contrast much less is known about plasminogen activation in other species. Bovine mastitis is an inflammatory disease of the mammary gland induced by various microorganisms, and a 20-fold increase in tPA activity has been reported in the milk of cows infected with Staphylococcus aureus (1). The activation of plasminogen by tPA is greatly increased by the R s2 -casein dimer (2), and in order to study this system in more detail it is necessary to obtain bovine tPA.…”

“…Tissue-type plasminogen activator (tPA) 1 and urokinase-type plasminogen activator (uPA) are the two major proteins responsible for conversion of plasminogen to plasmin. Although both tPA and uPA are related enzymes and activate plasminogen by cleavage of the same peptide bond, they have their own physiological features.…”