Glycerolipid formation and PGE2 and PGF2α production of rat renal papillae in vitro, the effects of urea

The glycerolipid production by rat renal papillary slices varied inversely with the urea concentration (0a–1660 mM) whether the production was measured as labelling of the glycerol backbone from glucose or as incorporation of labelled arachidonic acid and palmitic acid. The rate of phospholipid formation was most dependent on medium urea concentrations in the range between 0 and 1100 mM. The production of prostaglandins PGE₂ and PGF_2α, measured radioimmunologically or by an isotope derivative method was in the same range inversely related to the production of glycerolipids and chain elongations. The effect of urea on prostaglandin formation is probably indirectly caused by the inhibition of the phospholipid formation and chain elongation, since the effect was abolished by 1% defatted albumin in the medium. The data suggest that the level of free arachidonic acid within the cells is controlled to an important extent by glycerolipid formation and chain elongation.     

Fatty acid-binding to erythrocyte ghost membranes and transmembrane movement

Summary Palmitate binding to human erythrocyte ghost membranes has been investigated with ghost preparations suspended in 0.2% albumin solutions. Free unbound palmitate in the extracellular water phase was measured in equilibrium studies using albumin-filled acid loaded ghosts as small semipermeable bags. The apparent dissociation constant of binding to the membrane is 13.5 nM and the binding capacity 19 nmoles per 7.2 × 109 cells.The 0°C exchange efflux kinetics of palmitate from albumin-filled ghosts is described by a model, which provides estimates of the rate constant of membrane transfer, k₃ = 0.024 s^–1, independent of the molar ratio of palmitate to albumin () and of a mean dissociation rate constant of the palmitate-albumin complex, k₁ = 0.0015 s^–1 at 0.2, allowing for a heterogeneity of the palmitate binding to albumin.The values of a third kinetically determined dependent model constant, Q, the ratio of palmitate bound to the membrane inner surface to palmitate on intracellular albumin, are not different from the Q values obtained by equilibrium experiments.The temperature dependences of k₁ and k₃ in the interval 0°C to 15°C give activation energies of 96 and 103 kJ/mole, respectively. The 0°C exchange efflux increases about 2 fold in response to a rise of pH from 6 to 9. The results suggest a carrier mediated palmitate flux at low with a V_max about 2 pmoles min^–1 cm^–2 at 0°C pH 7.3.     

Long lasting anti-adrenergic effect of 7-oxo-prostacyclin in the heart: a cycloheximide sensitive increase of phosphodiesterase isoform I and IV activities

Evidence is accumulating that 7-oxo-prostacyclin (7-oxo-PGI₂) induces a delayed indirect anti-adrenergic and cytoprotective effect on the myocardium, the mechanism of which is still unclear. To demonstrate that a single application of 7-oxo-PGI₂ (50 g/kg i.m.) 48 h prior to starting experiments attenuates the isoprenaline inducible inotropic response and accumulation of cAMP, isolated hearts of pretreated animals were perfused in the Langendorff mode with and without isoprenaline (1 to 100 nM). The late anti-adrenergic effect of the drug was manifested by a significant attenuation in the elevation of cAMP levels as well as in contractile force development. This effect was not due to changes in cAMP generation as there were identical ₁-adrenoceptor densities and affinities (as calculated from [³H]-CGP binding studies), G_i and G_s protein patterns (as taken from Western blots) as well as adenylyl cyclase activity measurements in the hearts studied. The anti-adrenergic potency of 7-oxo-PGI₂, however, was found to be related to a significant rise in cyclic nucleotide hydrolysis by phosphodiesterase (PDE). Using the fast-performance liquid chromatographic separation for PDE isoforms, a significant increase in the activity of PDE isoforms I and IV (260±28 vs 110±12 pmol cGMP/min x enzyme fraction and 77±11 vs 34±3 pmol cAMP/min x enzyme fraction, respectively) was found in the solubilized fraction of cardiac membranes in comparison to untreated controls; PDE IV activity was also increased in the cytosolic fraction (106±14 vs 65±6 pmol cAMP/min x enzyme fraction). The hypothesis that the delayed anti-adrenergic effect of 7-oxo-PGI₂ is initiated by an induction and accelerated synthesis of PDE I and IV in the heart is underlined by the fact that cycloheximide suppresses completely both the rise in PDE activities and the anti-adrenergic effects studied. It is suggested that an inducible predominance of cAMP degradation over its generation may be of relevance in processes related to heart protection.     

Transferrin as a donor of iron to mitochondria Effect of pyrophosphate and relationship to mitochondrial metabolism and heme synthesis

Rat liver mitochondria accumulate iron mobilized from transferrin by pyrophosphate. The uptake has a very low energy dependence, but it is highly dependent on a functioning respiratory chain. Reduction of the ferric-iron-pyrophosphate complex is not linked to any specific respiratory complex. Half of the amount of iron accumulated is passed into heme. Iron once accumulated is very little accessible to chelation by added ferric or ferrous iron chelators. Iron uptake and heme synthesis are maximal if a suitable porphyrin substrate is added simultaneously with iron. The results represent further evidence that pyrophosphate is a possible candidate for intracellular iron transport. Also, the results suggest that iron uptake is coupled to simultaneous porphyrin uptake and heme synthesis.     

Biometeorology in austria: past,present and future

Biometeorology in Austria has been shaped by concepts, personalities, and technology. In early times, the branches of biometeorology that are usual today were already evident: agricultural and forest meteorology, phenology, medical biometeorology and balneology, aerial biometeorology, urban housing and stabling meteorology all started to emerge several centuries ago. From the 1920 up to 1936, Wilhelm Schmidt at the Agricultural University of Austria laid the foundations of modern biometeorology. He was followed by Franz Sauberer, who headed a Department of Biometeorology at the National Weather Service and devoted his active life totally to biometeorology. Several years after his untimely death, the Department was dissolved. Not until 1981 was biometeorology taken up again at the Agricultural University, where the tradition of Schmidt and Sauberer now lives on in several courses within the area of applied biometeorology: Micro-and Topoclimatology, Agricultural and Forest Meteorology and Atmospheric Radiation. Biometeorology, being an experimental science, has also been influenced by new technological developments. The early period was exclusively observational. During the late nineteenth and early twentieth centuries mechanical and simple electric instruments were used with strip-chart recorders. These time consuming methods have now been replaced by electronic devices, including data loggers and portable computers along with many new electronic sensors, which provide additional insight into biometeorological problems. Since computers also make it possible to solve some of the complicated equations of biometeorology, the future of this science seems to be bright, not only in Austria but throughout the world.     

Weather patterns and asthma epidemics in New York City and New Orleans,U.S.A.

Twenty-five years of data on asthmatic attacks in New Orleans (covering approximately 170,000 asthma attacks) have been analyzed to identify asthma epidemic days, defined as days on which an unusually high number of asthmatic individuals had attacks. Similar data covering three years was obtained for New York City. A preliminary examination of detailed meteoroligical data revealed a consistent meteorological pattern preceding and associated with such asthma epidemic days which consisted of a cold front preceding an asthma epidemic by one to three days followed by a high pressure system. The significance of these meteorological findings and their relationship to other environmental agents such as natural or man-made atmospheric pollutants that are likely to be associated with asthma attacks will be discussed.Presented at the Eighth International Congress of Biometeorology, 9–14 September 1979, Shefayim, Israel.