Effects of dexamethasone on carnitine metabolism in liver and extrahepatic tissues

The in vivo effects of dexamethasone administration on liver and extrahepatic tissue carnitine concentrations were assessed in 48-h-starved rats. In heart and kidney, but not in liver, dexamethasone significantly increased total carnitine concentration. Acute (2.5 h) treatment with 2-tetradecylglycidate (TDG), a specific inhibitor of carnitine palmitoyl transferase 1, not only increased total hepatic carnitine concentrations, but also permitted an effect of dexamethasone (a further increase in hepatic carnitine concentration). The results are discussed in terms of acute (substrate-mediated) and chronic (hormonal) control of carnitine turnover.     

Evidence for the presence of lipopolysaccharide in Treponema phagedenis (biotype Reiterii) but not in Treponema pallidum (Nichols)

Abstract Immunoblotting profiles of whole or protease-K-digested organisms with homologous antisera demonstrated the presence of a characteristic ladder pattern of smooth LPS in Treponema phagedenis . Periodic acid silver staining of SDS-PAGE gels confirmed these findings. However, when heterologous or homologous serum was reacted with Treponema pallidum , no such pattern or cross-reactions were observed. The significance of apparent absence of LPS in T. pallidum is discussed.     

Exposure to nuclear magnetic resonance imaging procedure attenuates morphine-induced analgesia in mice

Adult male mice exposed to a Nuclear Magnetic Resonance Imaging (NMRI) procedure during the mid-dark period and injected with morphine (10 mg/kg) failed to exhibit the normal nocturnally enhanced morphine analgesia response to a thermal stimulus that was displayed by mice exposed to a sham imaging procedure and treated with morphine (p less than .01). When tested during the mid-light period, animals exposed to the NMRI procedure and given morphine displayed attenuated analgesia levels relative to sham exposed mice (p less than .01) treated with morphine. However, the morphine induced analgesia was not totally abolished since the imaged mice still exhibited analgesia relative to saline treated mice (p less than .01). These results suggest that the magnetic and/or radio-frequency fields associated with the NMRI procedure alter both day- and night-time responses to morphine. These results may reflect magnetic field induced alterations in neuronal calcium binding and/or alterations in nocturnal pineal gland activity.     

Characterization of Met-139 as the photolabeled amino acid residue in the steroid binding site of sex hormone binding globulin using delta 6 derivatives of either testosterone or estradiol as unsubstituted photoaffinity labeling reagents.

Immunopurified human sex hormone binding globulin (SHBG) was photoinactivated and photolabeled by radioinert and radioactive photoaffinity labeling steroids delta 6-testosterone (delta 6-T) and delta 6-estradiol (delta 6-E2). The maximal levels of specific incorporation of these two reagents were 0.50 and 0.33 mol of label/mol of SHBG, respectively. Covalently labeled SHBG fractions were citraconylated, reduced, carboxymethylated, and cleaved by trypsin. Separation of tryptic digests by reverse-phase liquid chromatography gave single radioactive peaks at the same retention times with both steroid reagents. However, the two labeled peptidic fractions could be distinguished by capillary electrophoresis and immunodetection with anti-steroid antibodies, whereas the covalent attachment of radioactivity was confirmed by thin-layer chromatography on silica gel. Edman degradation of the two labeled peptides showed a single sequence His-Pro-Ile-([3H]X)-Arg corresponding to the pentapeptide His-Pro-Ile-Met-Arg 136-140 of SHBG sequence. The coincidence, in both cases, of the absence of an identifiable amino acid residue and of the elution of the most intense peak of radioactivity at the fourth cycle of Edman degradation suggests that the same Met-139 residue was labeled by delta 6-[1,2-3H2]T or by delta 6-[17 alpha-3H]E2. Liquid secondary ion mass spectrometry of the two peptides showed [M+H]+ ions at m/z 939.8 or 923.8, corresponding respectively to the addition of delta 6-T or delta 6-E2 to the pentapeptide. The presence of the steroid molecule in the delta 6-[3H]T-pentapeptide conjugate was confirmed by the difference of 2 mass units with the [M+H]+ peak of the delta 6-[4-14C]T-pentapeptide conjugate.     

Frequency of Erwinia carotovora in the Alyth Burn in eastern Scotland and the sources of the bacterium

Contamination of the Alyth Burn by Erwinia carotovora was monitored monthly over 2 years at nine sites spread over a distance of ca 20 km. The bacterium was detected only once in the upper reaches of the river where it flows in uninhabited moorland but frequency of detection and contamination level tended to increase progressively as the river flowed through the middle reaches mostly in grassland to the lower reaches in arable land where the bacterium was almost always present. Erwinia populations rose from < 10² cells/1 before May to frequently > 10³ but < 10⁴ cells/l thereafter at sites in the arable land zone. A similar pattern was found in the grassland zone except that erwinia numbers were lower. Erwinia numbers at one site in the arable land zone were positively and negatively correlated with the river water temperature and flow rate respectively when there was a 1 month lag between the environmental data and the population recorded. More than 80% of isolates tested were E. carotovora subsp. carotovora.
Water from field drains in arable fields, especially those recently planted with potatoes, was frequently contaminated by E.c. carotovora , with numbers and a temporal pattern similar to those of the Alyth Burn. Drainage water from non-arable fields was rarely contaminated. Infected and rotting potatoes deposited in rivers temporarily contaminated the water. Survival of E. carotovora in dilute phosphate buffer was greater at pH 5˙7 than at pH 7˙7 and they survived for at least 10 d in river water.     

Purification and characterization of a lysophospholipase from human amnionic membranes

We have identified the presence of a lysophospholipase in human placental tissues and have purified this enzyme from the amnion. The specific activity was highest in the amnion and decreased across adjacent tissues. The purification involved the use of DEAE-Sephadex, phenyl-Sepharose, hydroxylapatite, and sulfylpropyl Sephadex chromatography. The activity of the purified enzyme toward palmitoyl lysophosphatidylcholine is 2.5 mumol min-1 mg-1 and the pH optimum is 7.0. The enzyme is not inhibited by EDTA and does not appear to have a metal ion requirement. The enzyme may be of membrane origin; the purified enzyme requires the presence of detergent during storage. The effects of substrate composition and physical state on enzymatic activity were explored. The enzyme was not active toward mono-, di-, or triglycerides, nor toward diacyl phospholipid. The enzyme was active toward myristoyl and palmitoyl lysophosphatidylcholine at concentrations where these substrates spontaneously form micelles or where Triton X-100 was used to induce co-micellization of the substrate at low concentrations with detergent. A role for this enzyme in processing the lysophospholipid product of phospholipase A action must be considered in evaluating arachidonic acid production in human fetal membranes and placental tissue, particularly during the initiation of labor.