Characterisation of Pseudomonas rhamnolipids

The Gram negative organism, Pseudomonas aeruginosa, is often found in the lungs of patients with cystic fibrosis and other forms of severe bronchiectasis, where it secretes a number of extracellular toxins including the mono- and dirhamnolipids. The principal monorhamnolipid from P. aeruginosa has previously been identified as rhamnosyl-3-hydroxydecanoyl-3-hydroxydecanoate (Rh-C10.C10). A number of related mono- and dirhamnolipids have been purified from cultures of a clinical isolate of P. aeruginosa and identified by fast atom bombardment and electron impact mass spectrometry: these contain the 3-hydroxyoctanoyl-3-hydroxydecanoate (C8.C10) and 3-hydroxydecanoyl-3-hydroxydodecanoate (C10.C12) homologues. Structural isomers were also present where the order of the lipid linkage was transposed (Rh-C10.C8 and Rh-C12.C10). Unsaturated mono- and dirhamnolipids containing the 3-hydroxydecanoyl-3-hydroxydodec-5-enoate (C10.C12:1) lipid were also present.     

Is methyl-branching in alpha-tocopherol's "tail" important for its in vivo activity? Rat curative myopathy bioassay measurements of the vitamin E activity of three 2RS-n-alkyl-2,5,7,8-tetramethyl-6-hydroxychromans

The vitamin E activity of the acetates of three 2RS-n-alkyl-2,5,7,8-tetramethyl-6-hydroxychroman analogs of alpha-tocopherol have been measured and compared directly with all-rac-alpha-tocopheryl acetate, or indirectly via 2R,4'R,8'R-alpha-tocopheryl acetate, using the rat curative myopathy, plasma pyruvate kinase assay. The analogs with alkyl chain lengths of 11 and 13 carbons have activities which not only do not differ significantly (p greater than 0.05) from each other but also do not differ from that of all-rac-alpha-tocopheryl acetate. This finding indicates that methyl branching in the phytyl tail at the 4', 8', and 12' positions has little if any influence upon vitamin E activity. Thus physical interactions involving the methyl branches of the phytyl tail and the polyunsaturated moieties of membrane phospholipids are unimportant in vivo, insofar as this bioassay is concerned. However, the length of the hydrocarbon tail is important. This is indicated by the result obtained with the acetate of the analog with an alkyl chain length of 15 carbon atoms which had only 15% of the activity of 2R,4'R,8'R-alpha-tocopheryl acetate, i.e., 22% of the activity of all-rac-alpha-tocopheryl acetate since this form is 1.47 times less active than 2R,4'R,8'R-alpha-tocopheryl acetate in the curative myopathy bioassay (Weiser, Vecchi, & Schlachter, Internat. J. Vit. Nutr. Res. 55:149-158, 1985).     

Effects of spaceflight on the proliferation of jejunal mucosal cells

The mitotic indices, villus heights, and crypt depths were determined in each of three jejunal regions (proximal, middle, and distal) for five animals each in the flight, vivarium, and synchronous groups. Because of the rapid turnover of intestinal mucosal cells and the delay in recovering the flight animals, it is not known whether the proliferation of jejunal mucosal cells is affected by microgravity conditions associated with spaceflight. However, since there were no consistent differences between animals in the flight group and those in the synchronous and vivarium control groups, it appears that any effects of microgravity on the turnover of jejunal mucosal cells are short-lived. Thus, this study represents an initial step in determining the effects of microgravity on the proliferation and turnover of intestinal mucosal cells.     

Cross-linkage sites in type I collagen fibrils studied by neutron diffraction

Cross-links in tendon collagen are essential for the biomechanical strength of healthy tissue. The nature and position of these cross-links has long been a subject for conjecture. We have approached this problem in a non-destructive manner, by studying neutron diffraction from collagen fibrils that have been specifically deuterated by reduction at keto-amine and Schiff base groups with sodium borodeuteride (NaB2H4). The intensities of the first 23 meridional reflections were recorded for both native and reduced tendons. These data were used to calculate the neutron-scattering density profile of the 67 nm (D) repeat of type I collagen fibrils in rat tail tendon. This approach not only succeeds in determining the location of the cross-linkage sites with respect to the fibril structure, as projected onto the fibre axis, but also presents a novel form of the isomorphous derivative solution to the phase problem.     

Angiotensin II-producing proteases from granulomatous tissue reaction in mice infected with Schistosoma mansoni

1. Angiotensin I hydrolases, Mr 140,000 and Mr 70,000 were separated by gel filtration from Tris-HCl buffer extract of hepatic granulomas developed in mice with schistosomiasis. Two enzymes had different substrate specificity. 2. Mr 140,000 hydrolase activity was inhibited by captopril as reported for angiotensin converting enzyme (ACE), while that of Mr 70,000 hydrolase activity was inhibited by potato carboxypeptidase inhibitor. 3. An intermediary, des-Leu10-angiotensin I and then angiotensin II were formed from angiotensin I by Mr 70,000 hydrolase. 4. The findings suggest that Mr 70,000 enzyme is tissue carboxypeptidase A, and it generates angiotensin II in granulomatous inflammation as does ACE.     

Serum hormones and physical performance capacity in young boy athletes during a 1-year training period

Serum hormones and physical performance capacity in boy athletes (AG; n = 19) were investigated during a 1-year training period (between the ages of 11.6 and 12.6 years). Six young untrained boys served as the control group (CG). The mean serum testosterone concentration increased significantly in AG (P less than 0.05) following the training period from 2.92 nmol.l-1, SD 1.04 to 5.81 nmol.l-1, SD 1.33. Significant differences were not observed in the cortisol, sex hormone binding globulin and growth hormone levels during the follow-up period. The AG clearly increased speed (P less than 0.001), speed-strength (P less than 0.01-P less than 0.001) and anaerobic capacity (P less than 0.001) whereas CG had only slight increases (NS) in physical performance capacity during a 1-year period. During the last 6-month training period significant positive correlations (r = 0.49-0.58; P less than 0.05-P less than 0.01) were observed in AG between the relative changes in testosterone, testosterone:cortisol ratio and growth hormone and the relative performance change in speed, maximal isometric force and endurance, respectively. At the end of the period significant positive correlations were observed in all subjects between the level of testosterone and speed-strength (r = 0.52-0.64; P less than 0.01-P less than 0.001) and anaerobic capacity (r = 0.49; P less than 0.05). It was concluded that an increase in anabolic activity with the synchronous training already has positive effects on trainability and physical performance capacity at an early stage in puberty.     

The Effects of Brown Rust and Phosphate on Cold Acclimation in Winter Barley

The green leaf area of winter barley, cv. Sonja, sampled fromthe field at different times during winter was always greatestin plants grown at high soil phosphate and smallest in plantsgrown at low soil phosphate, and at each fertilizer level wasgreater in healthy plants than in plants infected by rust (Pucciniahordei). In leaves that survived the coldest period of winter,the percentage area that was damaged was increased by rust infectionwhich prevented the ameliorating effects of high soil P. Rustand low P interacted to reduce the increases in leaf area andshoot d. wt that occurred when higher temperatures prevailedin spring. Under controlled conditions in the laboratory, phosphate reducedthe injury suffered when plants not acclimated to low temperatureswere exposed to freezing conditions, but this effect was removedby rust infection. After rust infection, freezing temperatureswere damaging even to acclimated plants, particularly if grownwith low soil P. Evidence of visible symptoms, and quantitativemeasurements of electrolyte efflux from intact leaves, chlorophyllfluorescence in vivo, and ethane and ethylene evolution fromcold-acclimated plants, showed that infection raised the minimumtemperature at which tissues could survive without injury. Infectedleaves were more sensitive to low temperature post-sporulationthan presporulation. Measurements of electrolyte efflux andchlorophyll fluorescence on plants growing under cold conditionsshowed that infection inhibited the processes of acclimationto low temperatures. Winter barley, Puccinia hordei, injury, low temperature, acclimation