Production of surfactant protein C in the baculovirus expression system: the information required for correct folding and palmitoylation of SP-C is contained within the mature sequence

Surfactant protein C (SP-C) is synthesized in the alveolar type II cells of the lung as a 21 kDa propeptide which is proteolytically processed to a 4.2 kDa mature active form. The main function of this extremely hydrophobic protein is to enhance lipid insertion into the air/liquid interface in the lung upon inhalation. This is necessary to maintain a relatively low surface tension at this interface during breathing. In this report we describe the production of mature human SP-C in the baculovirus expression system. The recombinant protein contains a secondary structure with a high alpha-helical content (73%), comparable to native SP-C, as determined by circular dichroism and attenuated total reflection Fourier transform infrared analysis. The expressed protein is a mixture of dipalmitoylated (15%) and non-palmitoylated SP-C. This suggests that the information required for palmitoylation is contained within the sequence of the mature protein. The activity of the protein to insert phospholipids into a preformed monolayer of lipids at an air/liquid interface was determined with a captive bubble surfactometer. Recombinant SP-C significantly reduced the surface tension at the air/liquid interface during dynamic expansion and compression. We conclude that correctly folded, dipalmitoylated and active SP-C can be expressed in the baculovirus expression system. Our results may facilitate investigations into the relation between structure and function of SP-C and into protein palmitoylation in general.     

Quantum states engineering: Recurrence formula including states with even and odd numbers of photons

Abstract

A previous recurrence formula using the resonant atom-field interaction for the generation of a field state in a cavity is extended to arbitrary states having even and odd numbers of photons in their photon-number distribution.     

Bibliography on power system probabilistic analysis (1962-88)

A bibliography is presented on the subject of power system analysis from a probabilistic point of view. Comprising 269 references, this bibliography focuses on probabilistic loadflow, probabilistic short circuit, and probabilistic dynamic analysis (probabilistic security). An additional section covering general topics (analysis and engineering) and a list of previous bibliographies are also presented.<>     

Abnormalities of auditory evoked magnetic fields and structural changes in the left hemisphere of male schizophrenics--a magnetoencephalographic-magnetic resonance imaging study

Functional and structural changes in 10 DSM-III-R male schizophrenics and 10 healthy volunteers were investigated using magnetoencephalographically (MEG) detected long-latency (N100 m) auditory evoked fields (AEFs) and magnetic resonance imaging (MRI). The AEFs were characterized by single moving equivalent dipoles, which were superimposed on MRIs. There were significant differences in dipole orientations and in AEF latencies in the left hemisphere of schizophrenics, when compared to the controls. The MEG-detected alterations were found to be associated with a bilateral volume reduction of the posterior superior temporal gyrus (pSTG), which was more pronounced in the left hemisphere. Separate analysis of white and gray matter has shown that the pSTG volume reduction resulted from decreased gray matter volumes without white matter changes. Both the functional and the morphological data indicate a left-hemispheric disturbance in our patients.     

Effects of vitamins A and E on the antioxidative metabolism of weaning pigs given dietary fats of different qualities

Early weaned piglets were divided into eight groups of 6 animals each. The animals were fed diets differing in fat quality (4% soybean oil, POZ 5 or 176) and in the content of the vitamins A (5,000 or 20,000 I.U./kg) and E (25 or 125 I.U./kg) over a period of 7 weeks. At the beginning, on day 25 and 47 blood samples were taken and analysed for vitamin A and E. In liver, heart, M. longissimus dorsi and M. semitendinosus vitamin A, E and the TBA-reactive substances were analysed. Induced lipid peroxidation was assessed by the ethane and pentane production rate in the skeletal muscle. During the weaning period a decrease in the alpha-tocopherol level was observed. In groups with the lower doses of vitamin E this effect was more pronounced. After 47 days the alpha-tocopherol concentrations in plasma and heart and skeletal muscle fell about 25-30% by offering high doses of vitamin A compared to those groups fed low doses. Oxidized fats also led to lower tocopherol concentrations in muscle tissues. Hydrocarbon production in M. longissimus dorsi and M. semitendinosus was significantly reduced in groups with the high supplement of vitamin E. A tendentially opposite effect was seen in groups supplied with high levels of vitamin A or oxidized fat. Although retinyl esters in plasma are a minor fraction of the vitamin A activity, they present 99% of the vitamin A in the liver. The distribution pattern of the different retinyl esters was independent of the amount of supplementary vitamin A. In the present experiment 20,000 U of Vitamin A reduced plasma and tissue vitamin E levels. This effect led to an increase of lipid peroxidation indicated by the higher production of hydrocarbons. The results raise concerns about further increases of vitamin A supplementation in piglet feed.